FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
CENTRIFUGAL AIR-SENDING DEVICE, AIR-SENDING APPARATUS, AIRCONDITIONING
APPARATUS, AND REFRIGERATION CYCLE APPARATUS;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN
THE FOLLOWING SPECIFICATION 5 PARTICULARLY DESCRIBES THE INVENTION
AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

DESCRIPTION
Technical Field
[0001]
The present disclosure relates to a centrifugal air-sending device including a
scroll casing, and to an air-sending apparatus, an air-5 conditioning apparatus, and a
refrigeration cycle apparatus including the centrifugal air-sending device.
Background Art
[0002]
Some centrifugal air-sending device includes a centrifugal fan including a main
plate having a disk shape and many blades in a scroll casing, and a tongue portion
that is a narrowed portion necessary to achieve such a condition that air flowing into
the centrifugal fan through a suction port at the end of the centrifugal fan in its
rotational axis direction is blown in a centrifugal direction of the centrifugal fan and the
pressure of the air is increased. For example, the shape of the tongue portion in a
range from the main plate to the suction port is a straight shape when the tongue
portion is viewed from a discharge port of the centrifugal air-sending device. In the
centrifugal air-sending device, the air flow entering the scroll casing through the
suction port and traveling toward the discharge port may partially re-enter the scroll at
the tongue portion used as a branch point. The re-entry of the air flow is the cause
of a decrease in air-sending performance and an increase in noise level. In view of
this phenomenon, a centrifugal air-sending device has been proposed that has a
shape in which parts of a tongue portion of a casing in a rotational direction of an airsending
fan are shifted gradually in the rotational direction in a range from a suction
port to a main plate of the centrifugal fan (see, for example, Patent Literature 1).
With this structure and the tongue portion of the centrifugal air-sending device of
Patent Literature 1, the amount of re-entry of an air flow that is traveling toward the
discharge port may be reduced. Thus, the air-sending performance may be
improved and turbulent noise may be reduced.
Citation List
Patent Literature
[0003]
Patent Literature 1: Japanese Unexamined Patent Application Publication No.
2007-146817
Summary of Invention
Technical Problem
[0004]
In the centrifugal air-sending device of Patent Literature 1, however, the tongue
portion extends in a direction opposite to the rotational direction with a constant
clearance kept between the tongue portion and blades in a range from the main plate
to a side plate having the suction port. Therefore, in the centrifugal air-sending
device of Patent Literature 1, the pressure in the scroll casing locally fluctuates in the
vicinity of the tongue portion at the parts close to the main plate and the suction port,
which are different in terms of the amounts of an air flow traveling toward the
discharge port and an air flow re-entering the scroll. Thus, the noise level may
15 increase.
[0005]
The present disclosure has been made to solve the problem described above
and provides a centrifugal air-sending device in which noise is reduced, and an airsending
apparatus, an air-conditioning apparatus, and a refrigeration cycle apparatus
including the centrifugal air-sending device.
Solution to Problem
[0006]
A centrifugal air-sending device according to an embodiment of the present
disclosure includes an impeller including a main plate having a disk shape and a
plurality of blades arranged on a peripheral edge of the main plate, and a scroll
casing housing the impeller. The scroll casing includes a discharge portion including
a discharge port through which an air flow produced by the impeller is discharged,
and a scroll portion including at least one side wall covering the impeller in a direction
perpendicular to an axial direction of a rotational axis of the impeller and including a
suction port through which air is suctioned, a peripheral wall surrounding the impeller
in a direction parallel to the axial direction of the rotational axis, and a tongue portion
forming a curve surface, positioned between an end of the discharge portion and a
winding start portion of the peripheral wall, and configured to introduce the air flow
produced by the impeller to the discharge port. The tongue portion includes a first
area portion facing the main plate in the direction parallel to the 5 axial direction of the
rotational axis, and a second area portion positioned closer to the at least one side
wall than is the first area portion. In a section perpendicular to the rotational axis,
where the first area portion has a first vertex that is an intersection point of a curve
line formed by the tongue portion and a bisector of a first connection straight line
connecting the winding start portion and the end of the discharge portion, the second
area portion has a second vertex that is an intersection point of the curve line formed
by the tongue portion and a bisector of a second connection straight line connecting
the winding start portion and the end of the discharge portion, a virtual straight line
connecting the rotational axis and the first vertex is defined as a first straight line, and
a virtual straight line connecting the rotational axis and the second vertex is defined
as a second straight line, the second straight line is longer than the first straight line.
Advantageous Effects of Invention
[0007]
In the centrifugal air-sending device according to an embodiment of the present
disclosure, the tongue portion includes the first area portion facing the main plate in
the direction parallel to the axial direction of the rotational axis, and the second area
portion positioned closer to the side wall than is the first area portion. In the section
perpendicular to the rotational axis, the first area portion has the first vertex, which is
the intersection point of the curve line formed by the tongue portion and the bisector
of the first connection straight line connecting the winding start portion and the end of
the discharge portion. The second area portion has the second vertex, which is the
intersection point of the curve line formed by the tongue portion and the bisector of
the second connection straight line connecting the winding start portion and the end
of the discharge portion. When the virtual straight line connecting the rotational axis
and the first vertex is defined as the first straight line and the virtual straight line
connecting the rotational axis and the second vertex is defined as the second straight
line, the second straight line is longer than the first straight line. With this structure
of the tongue portion, a stagnation point of air flows at the tongue portion can be
shifted depending on an air flow around the main plate and an air flow around the
suction port, which are different in terms of their flow 5 directions. As a result, it is
possible to control, in the centrifugal air-sending device, the amount of the air flow
that re-enters the scroll portion with the stagnation point of air flows as a border.
Along with this, local pressure fluctuation can be suppressed. Thus, noise can be
reduced.

Brief Description of Drawings
[0008]
[Fig. 1] Fig. 1 is a perspective view of a centrifugal air-sending device
according to Embodiment 1 of the present disclosure.
[Fig. 2] Fig. 2 is a side view of the centrifugal air-sending device of Fig. 1 that is
viewed from a discharge port.
[Fig. 3] Fig. 3 is a sectional view of the centrifugal air-sending device that is cut
along a line A-A in Fig. 2.
[Fig. 4] Fig. 4 is a horizontal sectional view of the centrifugal air-sending device
of Fig. 1 at a part of a line B-B on the centrifugal air-sending device of Fig. 3.
[Fig. 5] Fig. 5 is a conceptual diagram illustrating a relationship between a
tongue portion and a rotational axis of an impeller in the centrifugal air-sending device
of Fig. 1.
[Fig. 6] Fig. 6 is a side view of a modified example of the centrifugal air-sending
device according to Embodiment 1 of the present disclosure that is viewed from the
discharge port.
[Fig. 7] Fig. 7 is a horizontal sectional view of the centrifugal air-sending device
of Fig. 6 at the part of the line B-B in Fig. 3.
[Fig. 8] Fig. 8 is a perspective view of a centrifugal air-sending device
according to Embodiment 2 of the present disclosure.
[Fig. 9] Fig. 9 is a side view of the centrifugal air-sending device of Fig. 8 that is
viewed from the discharge port.
[Fig. 10] Fig. 10 is a sectional view of the centrifugal air-sending device that is
cut along a line A-A in Fig. 9.
[Fig. 11] Fig. 11 is a horizontal sectional view of the 5 centrifugal air-sending
device of Fig. 8 at a part of a line B-B on the centrifugal air-sending device of Fig. 10.
[Fig. 12] Fig. 12 is a conceptual diagram illustrating a relationship between a
tongue portion and the rotational axis of the impeller in the centrifugal air-sending
device of Fig. 8.
[Fig. 13] Fig. 13 is a side view of a modified example of the centrifugal airsending
device according to Embodiment 2 of the present disclosure that is viewed
from the discharge port.
[Fig. 14] Fig. 14 is a horizontal sectional view of the centrifugal air-sending
device of Fig. 13 at the part of the line B-B in Fig. 10.
[Fig. 15] Fig. 15 is a perspective view of a centrifugal air-sending device
according to Embodiment 3 of the present disclosure.
[Fig. 16] Fig. 16 is a side view of the centrifugal air-sending device of Fig. 15
that is viewed from the discharge port.
[Fig. 17] Fig. 17 is a sectional view of the centrifugal air-sending device that is
cut along a line A-A in Fig. 16.
[Fig. 18] Fig. 18 is a horizontal sectional view of the centrifugal air-sending
device of Fig. 15 at a part of a line B-B on the centrifugal air-sending device of Fig.
17.
[Fig. 19] Fig. 19 is a conceptual diagram illustrating a relationship between a
tongue portion and the rotational axis of the impeller in the centrifugal air-sending
device of Fig. 15.
[Fig. 20] Fig. 20 is a side view of a modified example of the centrifugal airsending
device according to Embodiment 3 of the present disclosure that is viewed
from the discharge port.
[Fig. 21] Fig. 21 is a horizontal sectional view of the centrifugal air-sending
device of Fig. 20 at the part of the line B-B in Fig. 17.
[Fig. 22] Fig. 22 is a perspective view of a centrifugal air-sending device
according to Embodiment 4 of the present disclosure.
[Fig. 23] Fig. 23 is a side view of the centrifugal air-5 sending device of Fig. 22
that is viewed from the discharge port.
[Fig. 24] Fig. 24 is a sectional view of the centrifugal air-sending device that is
cut along a line A-A in Fig. 23.
[Fig. 25] Fig. 25 is a horizontal sectional view of the centrifugal air-sending
device of Fig. 22 at a part of a line B-B on the centrifugal air-sending device of Fig.
24.
[Fig. 26] Fig. 26 is a conceptual diagram illustrating a relationship between a
tongue portion and the rotational axis of the impeller in the centrifugal air-sending
device of Fig. 22.
[Fig. 27] Fig. 27 is a side view of a modified example of the centrifugal airsending
device according to Embodiment 4 of the present disclosure that is viewed
from the discharge port.
[Fig. 28] Fig. 28 is a horizontal sectional view of the centrifugal air-sending
device of Fig. 27 at the part of the line B-B in Fig. 24.
[Fig. 29] Fig. 29 is a diagram illustrating the structure of an air-sending
apparatus according to Embodiment 5 of the present disclosure.
[Fig. 30] Fig. 30 is a perspective view of an air-conditioning apparatus
according to Embodiment 6 of the present disclosure.
[Fig. 31] Fig. 31 is a diagram illustrating the internal structure of the air25
conditioning apparatus according to Embodiment 6 of the present disclosure.
[Fig. 32] Fig. 32 is a sectional view of the air-conditioning apparatus according
to Embodiment 6 of the present disclosure.
[Fig. 33] Fig. 33 is a diagram illustrating the structure of a refrigeration cycle
apparatus according to Embodiment 7 of the present disclosure.
Description of Embodiments
[0009]
A centrifugal air-sending device 1, a centrifugal air-sending device 1A, a
centrifugal air-sending device 1B, a centrifugal air-sending device 1C, an air-sending
apparatus 30, an air-conditioning apparatus 40, and a refrigeration cycle apparatus
according to Embodiments 1 to 7 of the present disclosure 5 are described below
with reference to the drawings. In the drawings including Fig. 1 to which reference is
made below, the relative relationship of dimensions of component elements and the
shapes of component elements may differ from an actual relationship and actual
shapes. In the drawings to which reference is made below, elements represented by
the same reference signs are identical or corresponding elements and are common
throughout the description herein. Terms of directions (for example, "up", "down",
"right", "left", "front", and "rear") are used as appropriate for facilitating understanding.
These terms are used only for convenience of the description but do not limit
dispositions and directions of devices or components.
[0010]
Embodiment 1
[Centrifugal Air-sending Device 1]
Fig. 1 is a perspective view of the centrifugal air-sending device 1 according to
Embodiment 1 of the present disclosure. Fig. 2 is a side view of the centrifugal air20
sending device 1 of Fig. 1 that is viewed from a discharge port 42a. Fig. 3 is a
sectional view of the centrifugal air-sending device 1 that is cut along a line A-A in Fig.
2. Fig. 4 is a horizontal sectional view of the centrifugal air-sending device 1 of Fig.
1 at a part of a line B-B on the centrifugal air-sending device 1 of Fig. 3. The basic
structure of the centrifugal air-sending device 1 is described with reference to Fig. 1 to
25 Fig. 4. The centrifugal air-sending device 1 is a multi-blade centrifugal air-sending
device 1 including an impeller 2 configured to produce an air flow, and a scroll casing
4 housing the impeller 2.
[0011]
(Impeller 2)
The impeller 2 is driven to rotate by a motor or other devices (not illustrated)
and forcibly sends air radially outward by a centrifugal force produced through the
rotation. As illustrated in Fig. 1 and Fig. 2, the impeller 2 includes a main plate 2a
having a disk shape, and a plurality of blades 2d arranged on a peripheral edge 2a1
of the main plate 2a. A shaft 2b is provided at the center 5 of the main plate 2a. A
fan motor (not illustrated) is connected to the center of the shaft 2b. The impeller 2
is rotated by a drive force of the motor. As illustrated in Fig. 2 and Fig. 4, the
impeller 2 has ring-shaped side plates 2c each facing the main plate 2a and
positioned at respective sets of the ends of the plurality of blades 2d opposite to sets
of the ends close to the main plate 2a in an axial direction of a rotational axis RS of
the shaft 2b. Each side plate 2c couples the plurality of blades 2d to keep a
positional relationship among the distal ends of the blades 2d and reinforce the
plurality of blades 2d. The impeller 2 may have a structure without the side plate 2c.
If the impeller 2 has the side plate 2c, one end of each of the plurality of blades 2d is
connected to the main plate 2a and the other end of each of the plurality of blades 2d
is connected to the side plate 2c. Thus, the plurality of blades 2d are disposed
between the main plate 2a and the side plate 2c. The impeller 2 is formed into a
cylindrical shape by the main plate 2a and the plurality of blades 2d and has a suction
port 2e close to each of the side plates 2c opposite to the main plate 2a in the axial
direction of the rotational axis RS of the shaft 2b.
[0012]
The plurality of blades 2d are disposed in a circular form around the shaft 2b
and the proximal ends are fixed onto the surface of the main plate 2a. As illustrated
in Fig. 2 and Fig. 4, pluralities of blades 2d are provided on both sides of the main
plate 2a in the axial direction of the rotational axis RS of the shaft 2b. The blades 2d
are disposed along the peripheral edge 2a1 of the main plate 2a at constant intervals.
For example, each blade 2d has a curved rectangular plate shape and is disposed
along a radial direction or inclined at a predetermined angle from the radial direction.
[0013]
The impeller 2 structured and rotated as described above can send air
suctioned into a space surrounded by the main plate 2a and the plurality of blades 2d
radially outward through spaces between adjacent blades 2d. In Embodiment 1,
each blade 2d is provided substantially upright from the main plate 2a but the posture
is not particularly limited to this posture. Each blade 5 2d may be inclined from a
direction perpendicular to the main plate 2a.
[0014]
(Scroll Casing 4)
The scroll casing 4 surrounds the impeller 2 and regulates a flow of air blown
from the impeller 2. The scroll casing 4 includes a discharge portion 42 and a scroll
portion 41. The discharge portion 42 has the discharge port 42a through which an
air flow produced by the impeller 2 and passing through the scroll portion 41 is
discharged. The scroll portion 41 has an air passage through which a dynamic
pressure of the air flow produced by the impeller 2 is converted into a static pressure.
The scroll portion 41 includes side walls 4a covering the impeller 2 in the axial
direction of the rotational axis RS of the shaft 2b of the impeller 2, and each having a
suction port 5 through which air is suctioned, and a peripheral wall 4c surrounding the
impeller 2 in a radial direction of the rotational axis RS of the shaft 2b. The scroll
portion 41 further includes a tongue portion 43 forming a curve surface, positioned
between a winding start portion 41a of the peripheral wall 4c and a connection portion
42f, which is an end of the discharge portion 42 closer to the peripheral wall 4c than is
the opposite end, and configured to introduce the air flow produced by the impeller 2
and passing through the scroll portion 41 to the discharge port 42a. The radial
direction of the shaft 2b is a direction perpendicular to the shaft 2b. An internal
space of the scroll portion 41 defined by the peripheral wall 4c and the side walls 4a
is a space where the air blown from the impeller 2 flows along the peripheral wall 4c.
[0015]
(Side Wall 4a)
Each side wall 4a is disposed perpendicular to the axial direction of the
rotational axis RS of the impeller 2 and covers the impeller 2. The side wall 4a of the
scroll casing 4 has the suction port 5 through which air can flow between the impeller
2 and the outside of the scroll casing 4. Further, the side wall 4a is provided with a
bell mouth 3 configured to guide an air flow to be suctioned into the scroll casing 4
through the suction port 5. The bell mouth 3 is formed in a part where the bell mouth
3 faces the suction port 2e of the impeller 2. The bell mouth 5 3 has an annular shape
in which an air passage is narrowed from an upstream end 3a, which is an end
located upstream in the air flow to be suctioned into the scroll casing 4 through the
suction port 5, toward a downstream end 3b, which is an end located downstream in
the air flow. The suction port 5 has a circular shape and is disposed such that the
center of the suction port 5 and the center of the shaft 2b of the impeller 2
substantially coincide with each other. With this structure of the side wall 4a, air in
the vicinity of the suction port 5 smoothly flows and efficiently enters the impeller 2
from the suction port 5. As illustrated in Fig. 1 to Fig. 4, the centrifugal air-sending
device 1 includes a double-suction scroll casing 4 including the side walls 4a each
having the suction port 5 on both sides of the main plate 2a in the axial direction of
the rotational axis RS of the shaft 2b. That is, the scroll casing 4 of the centrifugal
air-sending device 1 has two side walls 4a and the side walls 4a are disposed to face
each other.
[0016]
(Peripheral Wall 4c)
The peripheral wall 4c surrounds the impeller 2 in the radial direction of the
shaft 2b and has an inner peripheral surface facing the plurality of blades 2d on the
outer periphery of the impeller 2 in the radial direction. The peripheral wall 4c is
disposed in parallel to the axial direction of the rotational axis RS of the impeller 2 and
covers the impeller 2. As illustrated in Fig. 3, the peripheral wall 4c is provided in a
part ranging from the winding start portion 41a positioned at a boundary between the
tongue portion 43 and the scroll portion 41 to a winding end portion 41b positioned at
a boundary between the discharge portion 42 and the scroll portion 41 located away
from the tongue portion 43 along a rotational direction of the impeller 2. In the
peripheral wall 4c having a curve surface, the winding start portion 41a is an end
located upstream in an air flow produced by rotation of the impeller 2, and the winding
end portion 41b is an end located downstream in the air flow produced by the rotation
of the impeller 2.
[0017]
The peripheral wall 4c is wide in the axial direction 5 of the rotational axis RS of
the impeller 2. As illustrated in Fig. 3, the peripheral wall 4c has a spiral shape
defined by a predetermined expansion rate at which a distance from the rotational
axis RS of the shaft 2b gradually increases in the rotational direction of the impeller 2
(arrow R direction). That is, a distance between the peripheral wall 4c and the outer
periphery of the impeller 2 increases at a predetermined rate from the tongue portion
43 to the discharge portion 42 and the air passage area gradually increases.
Examples of the spiral shape defined by the predetermined expansion rate include
spiral shapes based on a logarithmic spiral, an Archimedean spiral, and an involute
curve. The inner peripheral surface of the peripheral wall 4c is a curve surface that
is smoothly curved along a circumferential direction of the impeller 2 from the winding
start portion 41a, which is a start of the spiral shape, to the winding end portion 41b,
which is an end of the spiral shape. With this structure, air sent out from the impeller
2 smoothly flows along a space between the impeller 2 and the peripheral wall 4c in a
direction of an arrow F1 in Fig. 3. Therefore, the static pressure of air from the
tongue portion 43 toward the discharge portion 42 efficiently increases in the scroll
casing 4.
[0018]
(Discharge Portion 42)
The discharge portion 42 is a hollow pipe having a rectangular section
orthogonal to the direction in which air flows along the peripheral wall 4c. As
illustrated in Fig. 3 and Fig. 4, the discharge portion 42 has a passage through which
air sent out from the impeller 2 and flowing along the space between the peripheral
wall 4c and the impeller 2 is guided such that the air is discharged into outside air.
One end of the discharge portion 42 is fixed to the scroll casing 4 to form an inflow
port 42g through which air flows into the discharge portion 42 from the scroll casing.
The other end of the discharge portion 42 forms the discharge port 42a through which
air flowing through the passage in the discharge portion 42 is discharged into the
outside air. An arrow F2 in Fig. 3 represents an air flow from the scroll casing 4
toward the discharge port 42a of the discharge portion 42.
[0019]
As illustrated in Fig. 1, the discharge portion 42 includes an extension plate
42b, a diffuser plate 42c, a first side plate 42d, and a second side plate 42e. The
extension plate 42b is integrated with the scroll casing 4 by extending smoothly to the
winding end portion 41b, which is the downstream end of the peripheral wall 4c. The
diffuser plate 42c extends to the tongue portion 43 of the scroll casing 4, faces the
extension plate 42b, and is positioned at a predetermined angle from the extension
plate 42b such that the sectional area of the passage gradually increases along the
air flow direction in the discharge portion 42. That is, the diffuser plate 42c extends
from the tongue portion 43 of the scroll casing 4 radially outward in the rotational
plate 42c includes a first diffuser portion 42c4 extending to a first area portion 43a
described later, and a second diffuser portion 42c5 extending to a second area
portion 43b described later. The first side plate 42d extends to the side wall 4a of
the scroll casing 4. The second side plate 42e extends to the opposite side wall 4a
of the scroll casing 4. The first side plate 42d and the second side plate 42e facing
each other are connected by the extension plate 42b and the diffuser plate 42c.
Thus, the discharge portion 42 has a passage having a rectangular section by the
extension plate 42b, the diffuser plate 42c, the first side plate 42d, and the second
side plate 42e.
[0020]
(Tongue Portion 43)
The scroll casing 4 has the tongue portion 43 between the diffuser plate 42c of
the discharge portion 42 and the winding start portion 41a of the peripheral wall 4c.
The tongue portion 43 introduces an air flow produced by the impeller 2 and passing
through the scroll portion 41 to the discharge port 42a. The tongue portion 43 is a
projection provided at a boundary between the scroll portion 41 and the discharge
portion 42. In the scroll casing 4, the tongue portion 43 extends in a direction
parallel to the axial direction of the rotational axis RS of the shaft 2b.
[0021]
As illustrated in Fig. 3, the tongue portion 43 is bent 5 to project toward the
passage at the inflow port 42g of the discharge portion 42. The tongue portion 43
has a predetermined curvature radius and the peripheral wall 4c is smoothly
connected to the diffuser plate 42c via the tongue portion 43. When air passing
through the suction ports 5 and sent out from the impeller 2 is gathered by the scroll
casing 4 and flows into the discharge portion 42, the tongue portion 43 is of use as a
branch point in the passage. That is, the inflow port 42g of the discharge portion 42
has a passage of an air flow toward the discharge port 42a (arrow F2) and a passage
of an air flow that re-enters the upstream portion from the tongue portion 43 (arrow
F3). The air flow traveling toward the discharge portion 42 has a static pressure
increasing while the air flow is passing through the scroll casing 4. Therefore, the
pressure is higher than the pressure in the scroll casing 4. The tongue portion 43 is
thus configured to define the pressure difference, and is configured to introduce the
air traveling toward the discharge portion 42 to the individual passages by the curve
surface.
[0022]
Fig. 5 is a conceptual diagram illustrating a relationship between the tongue
portion 43 and the rotational axis RS of the impeller 2 in the centrifugal air-sending
device 1 of Fig. 1. The structure of the tongue portion 43 is further described with
reference to Fig. 2 to Fig. 5. The tongue portion 43 includes the first area portion
43a facing the main plate 2a in the direction parallel to the axial direction of the
rotational axis RS of the impeller 2, and the second area portions 43b positioned
closer to the respective side walls 4a than is the first area portion 43a. When the
tongue portion 43 is viewed from the discharge port 42a as illustrated in Fig. 2, the
tongue portion 43 has a straight shape parallel to the rotational axis RS of the shaft
2b. That is, the tongue portion 43 is formed such that the first area portion 43a
facing the main plate 2a and the second area portions 43b connected to the
respective side walls 4a each having the suction port 5 are disposed on the same
straight line when the tongue portion 43 is viewed from the discharge port 42a. The
first area portion 43a is a part of the tongue portion 43 facing the main plate 2a of the
impeller 2 and positioned at the center of the tongue 5 portion 43 in the direction
parallel to the axial direction of the rotational axis RS of the shaft 2b. The second
area portion 43b is a part of the tongue portion 43 extending to each of the side walls
4a each having the suction port 5 and positioned at each end of the tongue portion 43
in the direction parallel to the axial direction of the rotational axis RS of the shaft 2b.
The first area portion 43a is a part of the tongue portion 43 positioned closer to the
main plate 2a than are the second area portions 43b. Each of the second area
portions 43b is a part of the tongue portion 43 positioned closer to the corresponding
suction port 5 than is the first area portion 43a. The second area portion 43b may
include not only the part of the tongue portion 43extending to the side wall 4a having
the suction port 5 but also a part of the tongue portion 43 positioned closer to the side
wall 4a than to the main plate 2a in the direction parallel to the axial direction of the
rotational axis RS of the shaft 2b.
[0023]
When the tongue portion 43 is viewed in a direction from the extension plate
42b to the diffuser plate 42c as illustrated in Fig. 4, the tongue portion 43 is curved
such that the first area portion 43a is positioned closer to the rotational axis RS of the
impeller 2 than are the second area portions 43b. In other words, when the tongue
portion 43 is viewed in the direction from the extension plate 42b to the diffuser plate
42c as illustrated in Fig. 4, the tongue portion 43 is curved such that the second area
portions 43b are positioned farther away from the rotational axis RS of the impeller 2
than is the first area portion 43a. That is, the tongue portion 43 has a smooth Ushape
such that the tongue portion 43 is positioned gradually away from the impeller
2 and close to the discharge port 42a with increasing distance from the first area
portion 43a to each of the second area portions 43b. As illustrated in Fig. 3 and Fig.
4, a part of the peripheral wall 4c extending to the tongue portion 43 has a shape
conforming to the shape of the tongue portion 43. That is, the peripheral wall 4c is
curved such that the part of the peripheral wall 4c is positioned gradually close to the
rotational axis RS of the impeller 2 with increasing distance from each of the side
walls 4a to the main plate 2a. That is, the scroll casing 4 is formed such that the
center of the tongue portion 43 and the center of the part of 5 the peripheral wall 4c
extending to the tongue portion 43 in the axial direction of the rotational axis RS of the
impeller 2 are gently recessed inward of the scroll casing 4. Thus, the peripheral
wall 4c is curved in a shape conforming to the shape of the tongue portion 43.
[0024]
The structure of the tongue portion 43 is described in more detail with
reference to Fig. 3 and Fig. 5. As described above, the tongue portion 43 is
positioned between the peripheral wall 4c and the diffuser plate 42c. The winding
start portion 41a is positioned at a boundary between the tongue portion 43 and the
peripheral wall 4c of the scroll portion 41. As illustrated in Fig. 3, in a section
perpendicular to the rotational axis RS of the shaft 2b, the winding start portion 41a is
an inflection point between a curve line of the tongue portion 43 and a curve line of
the peripheral wall 4c. In Fig. 5, a central winding start portion 41a1 is a winding
start portion 41a at the first area portion 43a. A terminal winding start portion 41a2 is
a winding start portion 41a at the second area portion 43b. As described above, the
peripheral wall 4c has the spiral shape in the section perpendicular to the rotational
axis RS of the impeller 2. As illustrated in Fig. 5, in the section perpendicular to the
rotational axis RS of the shaft 2b, the winding start portion 41a is positioned closer to
the discharge port 42a than is a virtual spiral curve 4c1 obtained by extending a curve
of the spiral shape in a direction opposite to the air flow direction.
[0025]
The connection portion 42f is positioned at a boundary between the tongue
portion 43 and the diffuser plate 42c of the discharge portion 42. When the diffuser
plate 42c is a plate having a curve surface, the connection portion 42f is an inflection
point between the curve line of the tongue portion 43 and a curve line of the diffuser
plate 42c in the section perpendicular to the rotational axis RS of the shaft 2b. When
the diffuser plate 42c is a flat plate, as illustrated in Fig. 3, the connection portion 42f,
which is the end of the discharge portion 42 closer to the peripheral wall 4c than is the
opposite end, is a boundary between a straight line of the diffuser plate 42c and the
curve line of the tongue portion 43 in the section perpendicular to the rotational axis
RS of the shaft 2b. In Fig. 5, a central connection portion 5 42f1 is a connection
portion 42f at the first area portion 43a. A terminal connection portion 42f2 is a
connection portion 42f at the second area portion 43b. As illustrated in Fig. 5, the
central connection portion 42f1 and the terminal connection portion 42f2 are disposed
at different positions in the section perpendicular to the rotational axis RS of the shaft
2b. As illustrated in Fig. 3, the connection portion 42f positioned at the boundary
between the tongue portion 43 and the diffuser plate 42c is an end of the tongue
portion 43 and also an end of the diffuser plate 42c. In the section perpendicular to
the rotational axis RS of the shaft 2b, the first diffuser portion 42c4 having the central
connection portion 42f1 as its end and the second diffuser portion 42c5 having the
15 terminal connection portion 42f2 as its end have different discharge port angles.
More specifically, in the section perpendicular to the rotational axis RS of the shaft 2b,
a virtual straight line connecting the rotational axis RS of the shaft 2b and a discharge
port end 42c1 of the diffuser plate 42c included in the discharge port 42a is defined as
a reference straight line T. An angle between the first diffuser portion 42c4 and the
reference straight line T is defined as a first discharge port angle 1. An angle
between the second diffuser portion 42c5 and the reference straight line T is defined
as a second discharge port angle 2. In the centrifugal air-sending device 1, the
second discharge port angle 2 of the second diffuser portion 42c5 is larger than the
first discharge port angle 1 of the first diffuser portion 42c4.
[0026]
As illustrated in Fig. 5, the tongue portion 43 has a first vertex 44 and a second
vertex 45 in the section perpendicular to the rotational axis RS of the impeller 2. The
first vertex 44 is a vertex of the tongue portion 43 at the first area portion 43a. In the
section perpendicular to the rotational axis RS of the impeller 2, the first vertex 44 is
an intersection point of the curve line formed by the tongue portion 43 and a bisector
E1 of a first connection straight line LS1 connecting the central winding start portion
41a1 and the central connection portion 42f1. The first connection straight line LS1
and the bisector E1 intersect at a right angle in the section perpendicular to the
rotational axis RS of the shaft 2b. The second vertex 45 is a vertex of the tongue
portion 43 at the second area portion 43b. In the 5 section perpendicular to the
rotational axis RS of the impeller 2, the second vertex 45 is an intersection point of
the curve line formed by the tongue portion 43 and a bisector E2 of a second
connection straight line LS2 connecting the terminal winding start portion 41a2 and
the terminal connection portion 42f2. The second connection straight line LS2 and
the bisector E2 intersect at a right angle in the section perpendicular to the rotational
axis RS of the shaft 2b.
[0027]
A virtual straight line connecting the rotational axis RS of the impeller 2 and the
first vertex 44 is defined as a first straight line L1. A virtual straight line connecting
15 the rotational axis RS of the impeller 2 and the second vertex 45 is defined as a
second straight line L2. In the centrifugal air-sending device 1, the first straight line
L1 connecting the first vertex 44 and the rotational axis RS is shorter than the second
straight line L2 connecting the second vertex 45 and the rotational axis RS in the
section perpendicular to the rotational axis RS of the shaft 2b. In other words, in the
centrifugal air-sending device 1, the second straight line L2 connecting the second
vertex 45 and the rotational axis RS is longer than the first straight line L1 connecting
the first vertex 44 and the rotational axis RS in the section perpendicular to the
rotational axis RS of the shaft 2b. Therefore, the second vertex 45 of the second
area portion 43b is positioned farther away from the rotational axis RS than is the first
vertex 44 of the first area portion 43a. Thus, in the section perpendicular to the
rotational axis RS of the shaft 2b, the space between the impeller 2 and the tongue
portion 43 is wider in the second area portion 43b than in the first area portion 43a.
As illustrated in Fig. 3, in the centrifugal air-sending device 1, the second vertex 45 is
positioned closer to the discharge port end 42c1 than is the first vertex 44 on a line
between the rotational axis RS and the discharge port end 42c1 on the reference
19
straight line T. Thus, in the section perpendicular to the rotational axis RS of the
shaft 2b, the space between the impeller 2 and the tongue portion 43 is wider in the
second area portion 43b than in the first area portion 43a.
[0028]
Fig. 6 is a side view of a modified example of the centrifugal 5 air-sending device
1 according to Embodiment 1 of the present disclosure that is viewed from the
discharge port 42a. Fig. 7 is a horizontal sectional view of a centrifugal air-sending
device 11 of Fig. 6 at the part of the line B-B in Fig. 3. Although the double-suction
centrifugal air-sending device 1 is described with reference to Fig. 1 to Fig. 5, the
centrifugal air-sending device 1 is not limited to the double-suction centrifugal airsending
device 1 but may be a single-suction centrifugal air-sending device 11.
Thus, the centrifugal air-sending device 11 is only required to have at least one side
wall 4a having the suction port 5. The scroll portion 41 of the centrifugal air-sending
device 11 includes the side wall 4a covering the impeller 2 in the axial direction of the
rotational axis RS of the shaft 2b of the impeller 2, and having the suction port 5
through which air is suctioned, and the peripheral wall 4c surrounding the impeller 2
in the radial direction of the rotational axis RS of the shaft 2b. The scroll portion 41
of the single-suction centrifugal air-sending device 11 further includes a side wall 4d
perpendicular to the axial direction of the rotational axis RS. The side wall 4d has no
suction port 5. The side wall 4d and the side wall 4a face each other. As illustrated
in Fig. 6 and Fig. 8, the plurality of blades 2d of the centrifugal air-sending device 11
are provided on one side of the main plate 2a in the axial direction of the rotational
axis RS of the shaft 2b.
[0029]
The tongue portion 43 of the centrifugal air-sending device 11 includes the first
area portion 43a facing the main plate 2a in the direction parallel to the axial direction
of the rotational axis RS of the impeller 2, and the second area portion 43b positioned
closer to the side wall 4a than is the first area portion 43a. When the tongue portion
43 is viewed from the discharge port 42a as illustrated in Fig. 6, the tongue portion 43
has a straight shape parallel to the rotational axis RS of the shaft 2b. That is, the
tongue portion 43 is formed such that the first area portion 43a facing the main plate
2a and the second area portion 43b connected to the side wall 4a having the suction
port 5 are disposed on the same straight line when the tongue portion 43 is viewed
from the discharge port 42a. The first area portion 43a is a part of the tongue portion
43 facing the main plate 2a of the impeller 2 and positioned 5 close to one end of the
tongue portion 43 in the direction parallel to the axial direction of the rotational axis
RS of the shaft 2b. The second area portion 43b is a part of the tongue portion 43
extending to the side wall 4a having the suction port 5 and positioned close to the
other end of the tongue portion 43 in the direction parallel to the axial direction of the
rotational axis RS of the shaft 2b. The first area portion 43a is a part of the tongue
portion 43 positioned closer to the main plate 2a than is the second area portion 43b.
The second area portion 43b is a part of the tongue portion 43 positioned closer to
the suction port 5 than is the first area portion 43a. The second area portion 43b
may include not only the part of the tongue portion 43 extending to the side wall 4a
having the suction port 5 but also a part of the tongue portion 43 positioned closer to
the side wall 4a than to the main plate 2a in the direction parallel to the axial direction
of the rotational axis RS of the shaft 2b.
[0030]
When the tongue portion 43 is viewed in a direction from the extension plate
42b to the diffuser plate 42c as illustrated in Fig. 7, the tongue portion 43 is curved
such that the first area portion 43a is positioned closer to the rotational axis RS of the
impeller 2 than is the second area portion 43b. In other words, when the tongue
portion 43 is viewed in the direction from the extension plate 42b to the diffuser plate
42c, the tongue portion 43 is curved such that the second area portion 43b is5 positioned farther away from the rotational axis RS of the impeller 2 than is the first
area portion 43a. That is, the tongue portion 43 is smoothly curved such that the
tongue portion 43 is positioned gradually away from the impeller 2 and close to the
discharge port 42a with increasing distance from the first area portion 43a to the
second area portion 43b. Further, a part of the peripheral wall 4c extending to the
tongue portion 43 has a shape conforming to the shape of the tongue portion 43.
That is, the peripheral wall 4c is curved such that the part of the peripheral wall 4c is
positioned gradually close to the rotational axis RS of the impeller 2 with increasing
distance from the side wall 4a to the main plate 2a. That is, the scroll casing 4 is
formed such that the part of the tongue portion 43positioned closer to the side wall 4d
and the part of the peripheral wall 4c extending to the 5 tongue portion 43 and
positioned closer to the side wall 4d in the axial direction of the rotational axis RS of
the impeller 2 are gently recessed inward of the scroll casing 4. Thus, the peripheral
wall 4c is curved in a shape conforming to the shape of the tongue portion 43.
[0031]
[Operation of Centrifugal Air-sending Device 1]
When the impeller 2 rotates, air outside the scroll casing 4 is suctioned into the
scroll casing 4 through the suction ports 5. The air suctioned into the scroll casing 4
is guided by the bell mouths 3 and suctioned into the impeller 2. The air suctioned
into the impeller 2 causes an air flow to which a dynamic pressure and a static
pressure are applied while the air passes through the plurality of blades 2d. The air
flow is blown radially outward from the impeller 2. While the air flow blown from the
impeller 2 is guided between the inner surface of the peripheral wall 4c and the
blades 2d in the scroll portion 41, the dynamic pressure is converted into a static
pressure. After the air flow blown from the impeller 2 passes through the scroll
portion 41, the air flow is blown out of the scroll casing 4 from the discharge port 42a
of the discharge portion 42 (arrow F2). The air flow blown from the impeller 2
concentrates at the main plate 2a. A part of the air flow blown from the main plate
2a impinges on the inner surface of the peripheral wall 4c of the scroll portion 41 and
flows toward the suction ports 5 along the peripheral wall 4c of the scroll portion 41.
The air flow around the main plate 2a and the air flow having flowed toward the
suction ports 5 are different in terms of their flow directions. After the air flows are
guided between the inner surface of the peripheral wall 4c and the blades 2d in the
scroll portion 41 and pass through the scroll portion 41, a part of the air flows reenters
the scroll portion 41 with the tongue portion 43 as a border (arrow F3).
[0032]
[Advantageous Effects of Centrifugal Air-sending Device 1]
As described above, the tongue portion 43 of the centrifugal air-sending device
1 includes the first area portion 43a facing the main plate 2a in the direction parallel to
the axial direction of the rotational axis RS, and 5 the second area portions 43b
positioned closer to the respective side walls 4a than is the first area portion 43a.
The first area portion 43a has the first vertex 44 in the section perpendicular to the
rotational axis RS. The first vertex 44 is the intersection point of the curve line
formed by the tongue portion 43 and the bisector E1 of the first connection straight
line LS1 connecting the winding start portion 41a and the connection portion 42f,
which is the end of the discharge portion 42. The second area portion 43b has the
second vertex 45, which is the intersection point of the curve line formed by the
tongue portion 43 and the bisector E2 of the second connection straight line LS2
connecting the winding start portion 41a and the connection portion 42f, which is the
end of the discharge portion 42 closer to the peripheral wall 4c than is the opposite
end. When the virtual straight line connecting the rotational axis RS and the first
vertex 44 is defined as the first straight line L1 and the virtual straight line connecting
the rotational axis RS and the second vertex 45 is defined as the second straight line
L2, the second straight line L2 is longer than the first straight line L1. With this
structure of the tongue portion 43, a stagnation point of air flows at the tongue portion
43 can be shifted depending on the air flow around the main plate 2a and the air flow
around the suction ports 5 that are different in terms of their flow directions. As a
result, it is possible to control, in the centrifugal air-sending device 1, the amount of
the air flow that re-enters the scroll portion 41 with the stagnation point of air flows as
the border. Along with this, local pressure fluctuation can be suppressed. Thus,
noise can be reduced.
[0033]
The winding start portion 41a is positioned closer to the discharge port 42a
than is the virtual spiral curve 4c1 obtained by extending the curve of the spiral shape
in the direction opposite to the air flow direction. With this structure of the centrifugal
air-sending device 1, the stagnation point of air flows at the tongue portion 43 can be
shifted depending on the air flow around the main plate 2a and the air flow around the
suction ports 5 that are different in terms of their flow directions. As a result, it is
possible to control, in the centrifugal air-sending device 1, the amount of the air flow
that re-enters the scroll portion 41 with the stagnation point of air 5 flows as the border.
Along with this, the local pressure fluctuation can be suppressed. Thus, noise can
be reduced.
[0034]
In the centrifugal air-sending device 1, in the section perpendicular to the
rotational axis RS, the virtual straight line connecting the rotational axis RS and the
discharge port end 42c1 of the diffuser plate 42c included in the discharge port 42a is
defined as the reference straight line T. The angle between the first diffuser portion
42c4 and the reference straight line T is defined as the first discharge port angle 1.
The angle between the second diffuser portion 42c5 and the reference straight line T
is defined as the second discharge port angle 2. In this case, the second discharge
port angle 2 is larger than the first discharge port angle 1. With this structure of
the centrifugal air-sending device 1, the stagnation point of air flows at the tongue
portion 43 can be shifted depending on the air flow around the main plate 2a and the
air flow around the suction ports 5 that are different in terms of their flow directions.
As a result, it is possible to control, in the centrifugal air-sending device 1, the amount
of the air flow that re-enters the scroll portion 41 with the stagnation point of air flows
as the border. Along with this, the local pressure fluctuation can be suppressed.
Thus, noise can be reduced.
[0035]
In the tongue portion 43, the second vertex 45 is positioned closer to the
discharge port end 42c1 than is the first vertex 44 on the line between the rotational
axis RS and the discharge port end 42c1 on the reference straight line T. With this
structure of the centrifugal air-sending device 1, the stagnation point of air flows at the
tongue portion 43 can be shifted depending on the air flow around the main plate 2a
and the air flow around the suction ports 5 that are different in terms of their flow
directions. As a result, it is possible to control, in the centrifugal air-sending device
1, the amount of the air flow that re-enters the scroll portion 41 with the stagnation
point of air flows as the border. Along with this, the local pressure fluctuation can be
suppressed. Thus, noise can be reduced.
[0036]
The tongue portion 43 is curved such that the second area portions 43b are
positioned farther away from the rotational axis RS than is the first area portion 43a.
With this structure of the centrifugal air-sending device 1, the stagnation point of air
flows at the tongue portion 43 can be shifted depending on the air flow around the
main plate 2a and the air flow around the suction ports 5 that are different in terms of
their flow directions. As a result, it is possible to control, in the centrifugal airsending
device 1, the amount of the air flow that re-enters the scroll portion 41 with
the stagnation point of air flows as the border. Along with this, the local pressure
fluctuation can be suppressed. Thus, noise can be reduced.
[0037]
The peripheral wall 4c is curved in a shape conforming to the shape of the
tongue portion 43. With the structure of the tongue portion 43 of the centrifugal airsending
device 1, the stagnation point of air flows at the tongue portion 43 can be
shifted depending on the air flow around the main plate 2a and the air flow around the
suction ports 5 that are different in terms of their flow directions. As the peripheral
wall 4c is curved in the shape conforming to the shape of the tongue portion 43, the
air flows can be introduced smoothly. As a result, it is possible to control, in the
centrifugal air-sending device 1, the amount of the air flow that re-enters the scroll
portion 41 with the stagnation point of air flows as the border. Along with this, the
local pressure fluctuation can be suppressed. Thus, noise can be reduced.
[0038]
Embodiment 2
Fig. 8 is a perspective view of a centrifugal air-sending device 1A according to
Embodiment 2 of the present disclosure. Fig. 9 is a side view of the centrifugal air30
sending device 1A of Fig. 8 that is viewed from the discharge port 42a. Fig. 10 is a
sectional view of the centrifugal air-sending device 1A that is cut along a line A-A in
Fig. 9. Fig. 11 is a horizontal sectional view of the centrifugal air-sending device 1A
of Fig. 8 at a part of a line B-B on the centrifugal air-sending device 1A of Fig. 10.
Fig. 12 is a conceptual diagram illustrating a relationship between a tongue portion
143 and the rotational axis RS of the impeller 2 in the centrifugal 5 air-sending device
1A of Fig. 8. Portions having the same structures as those of the centrifugal airsending
device 1 of Fig. 1 to Fig. 5 are represented by the same reference signs and
description of the portions is omitted. The centrifugal air-sending device 1A
according to Embodiment 2 is different from the centrifugal air-sending device 1
10 according to Embodiment 1 in terms of the structure of the tongue portion 43. The
structures of portions other than the tongue portion 43 are similar to the structures in
the centrifugal air-sending device 1 according to Embodiment 1. Thus, the following
description is mainly directed to the structure of the tongue portion 143 of the
centrifugal air-sending device 1A according to Embodiment 2 with reference to Fig. 8
to Fig. 12.
[0039]
(Tongue Portion 143)
The scroll casing 4 has the tongue portion 143 between the diffuser plate 42c
of the discharge portion 42 and a winding start portion 141a of the peripheral wall 4c.
The tongue portion 143 introduces an air flow produced by the impeller 2 and passing
through the scroll portion 41 to the discharge port 42a. The tongue portion 143 is a
projection provided at the boundary between the scroll portion 41 and the discharge
portion 42. In the scroll casing 4, the tongue portion 143 extends in the direction
parallel to the axial direction of the rotational axis RS of the shaft 2b.
[0040]
As illustrated in Fig. 10, the tongue portion 143 is bent to project toward the
passage at the inflow port 42g of the discharge portion 42. The tongue portion 143
has a predetermined curvature radius and the peripheral wall 4c is smoothly
connected to the diffuser plate 42c via the tongue portion 143. When air passing
through the suction ports 5 and sent out from the impeller 2 is gathered by the scroll

casing 4 and flows into the discharge portion 42, the tongue portion 143 is of use as a
branch point in the passage. That is, the inflow port 42g of the discharge portion 42
has a passage of an air flow toward the discharge port 42a (arrow F2) and a passage
of an air flow that re-enters the upstream portion from the tongue portion 143 (arrow
F3). The air flow traveling toward the discharge 5 portion 42 has a static pressure
increasing while the air flow is passing through the scroll casing 4. Therefore, the
pressure is higher than the pressure in the scroll casing 4. The tongue portion 143 is
thus configured to define the pressure difference, and is configured to introduce the
air traveling toward the discharge portion 42 to the individual passages by the curve
surface.
[0041]
The structure of the tongue portion 143 is further described with reference to
Fig. 9 to Fig. 12. The tongue portion 143 includes a first area portion 143a facing the
main plate 2a in the direction parallel to the axial direction of the rotational axis RS of
the impeller 2, and second area portions 143b positioned closer to the respective side
walls 4a than is the first area portion 143a. When the tongue portion 143 is viewed
from the discharge port 42a as illustrated in Fig. 9, the tongue portion 143 is curved in
a U-shape such that the first area portion 143a is positioned close to the rotational
axis RS of the shaft 2b. That is, in the centrifugal air-sending device 1A, when the
tongue portion 143 is viewed from the discharge port 42a, the first area portion 143a
facing the main plate 2a is positioned closer to the rotational axis RS of the shaft 2b
than is the second area portions 143b connected to the respective side walls 4a each
having the suction port 5. The tongue portion 143 is formed such that the first area
portion 143a facing the main plate 2a and the second area portions 143b connected
to the respective side walls 4a each having the suction port 5 are disposed on the
same curve line when the tongue portion 143 is viewed from the discharge port 42a.
The first area portion 143a is a part of the tongue portion 143 facing the main plate 2a
of the impeller 2 and positioned at the center of the tongue portion 143 in the direction
parallel to the axial direction of the rotational axis RS of the shaft 2b. The second
area portion 143b is a part of the tongue portion 143 extending to each of the side
walls 4aeach having the suction port 5 and positioned at each end of the tongue
portion 143 in the direction parallel to the axial direction of the rotational axis RS of
the shaft 2b. The first area portion 143a is a part of the tongue portion 143
positioned closer to the main plate 2a than are the second area portions 143b. Each
of the second area portions 143b is a part of the tongue 5 portion 143 positioned closer
to the corresponding suction port 5 than is the first area portion 143a. The second
area portion 143b may include not only the part of the tongue portion 143 extending
to the side wall 4a having the suction port 5 but also a part of the tongue portion 143
positioned closer to the side wall 4a than to the main plate 2a in the direction parallel
to the axial direction of the rotational axis RS of the shaft 2b.
[0042]
When the tongue portion 143 is viewed in a direction from the extension plate
42b to the diffuser plate 42c as illustrated in Fig. 11, the tongue portion 143 is curved
such that the first area portion 143a is positioned closer to the rotational axis RS of
the impeller 2 than are the second area portions 143b. In other words, when the
tongue portion 143 is viewed in the direction from the extension plate 42b to the
diffuser plate 42c as illustrated in Fig. 11, the tongue portion 143 is curved such that
the second area portions 143b are positioned farther away from the rotational axis RS
of the impeller 2 than is the first area portion 143a. That is, the tongue portion 143
has a smooth U-shape such that the tongue portion 143 is positioned gradually away
from the impeller 2 and close to the discharge port 42a with increasing distance from
the first area portion 143a to each of the second area portions 143b. As illustrated in
Fig. 10 and Fig. 11, a part of the peripheral wall 4c extending to the tongue portion
143 has a shape conforming to the shape of the tongue portion 143. That is, the
peripheral wall 4c is curved such that the part of the peripheral wall 4c is positioned
gradually close to the rotational axis RS of the impeller 2 with increasing distance
from each of the side walls 4a to the main plate 2a. That is, the scroll casing 4 is
formed such that the center of the tongue portion 143 and the center of the part of the
peripheral wall 4c extending to the tongue portion 143 in the axial direction of the
rotational axis RS of the impeller 2 are gently recessed inward of the scroll casing 4.
Thus, the peripheral wall 4c is curved in a shape conforming to the shape of the
tongue portion 143. Compared with the centrifugal air-sending device 1 according to
Embodiment 1, the centrifugal air-sending device 1A is formed such that each of the
second area portions 143b is positioned closer to the extension plate 42b than is the
first area portion 143a and bulges toward the passage at the 5 inflow port 42g more
than does the first area portion 143a.
[0043]
The structure of the tongue portion 143 is described in more detail with
reference to Fig. 10 and Fig. 12. The tongue portion 143 is positioned between the
peripheral wall 4c and the diffuser plate 42c. The winding start portion 141a is
positioned at a boundary between the tongue portion 143 and the peripheral wall 4c
of the scroll portion 41. As illustrated in Fig. 10, in the section perpendicular to the
rotational axis RS of the shaft 2b, the winding start portion 141a is an inflection point
between a curve line of the tongue portion 143 and the curve line of the peripheral
15 wall 4c. A central winding start portion 141a1 is a winding start portion 141a at the
first area portion 143a. A terminal winding start portion 141a2 is a winding start
portion 141a at the second area portion 143b. As described above, the peripheral
wall 4c has the spiral shape in the section perpendicular to the rotational axis RS of
the impeller 2. As illustrated in Fig. 12, in the section perpendicular to the rotational
axis RS of the shaft 2b, the winding start portion 141a is positioned closer to the
discharge port 42a than is the virtual spiral curve 4c1 obtained by extending the curve
of the spiral shape in the direction opposite to the air flow direction.
[0044]
A connection portion 142f is positioned at a boundary between the tongue
portion 143 and the diffuser plate 42c of the discharge portion 42. When the diffuser
plate 42c is a plate having a curve surface, the connection portion 142f is an inflection
point between the curve line of the tongue portion 143 and the curve line of the
diffuser plate 42c in the section perpendicular to the rotational axis RS of the shaft 2b.
When the diffuser plate 42c is a flat plate, as illustrated in Fig. 10, the connection
portion 142f, which is the end of the discharge portion 42 closer to the peripheral wall

4c than is the opposite end, is a boundary between the straight line of the diffuser
plate 42c and the curve line of the tongue portion 143 in the section perpendicular to
the rotational axis RS of the shaft 2b. A central connection portion 142f1 is a
connection portion 142f at the first area portion 143a. A terminal connection portion
142f2 is a connection portion 142f at the second area portion 5 143b. As illustrated in
Fig. 12, the central connection portion 142f1 and the terminal connection portion
142f2 are disposed at different positions in the section perpendicular to the rotational
axis RS of the shaft 2b. As illustrated in Fig. 10, the connection portion 142f
positioned at the boundary between the tongue portion 143 and the diffuser plate 42c
is an end of the tongue portion 143 and also the end of the diffuser plate 42c. In the
section perpendicular to the rotational axis RS of the shaft 2b, the first diffuser portion
42c4 having the central connection portion 142f1 as its end and the second diffuser
portion 42c5 having the terminal connection portion 142f2 as its end have different
discharge port angles. More specifically, in the section perpendicular to the
rotational axis RS of the shaft 2b, a virtual straight line connecting the rotational axis
RS of the shaft 2b and the discharge port end 42c1 of the diffuser plate 42c included
in the discharge port 42a is defined as the reference straight line T. An angle
between the first diffuser portion 42c4 and the reference straight line T is defined as a
first discharge port angle 11. An angle between the second diffuser portion 42c5
and the reference straight line T is defined as a second discharge port angle 12. In
the centrifugal air-sending device 1A, the second discharge port angle 12 of the
second diffuser portion 42c5 is larger than the first discharge port angle 11 of the
first diffuser portion 42c4.
[0045]
As illustrated in Fig. 12, the tongue portion 143 has a first vertex 144 and a
second vertex 145. The first vertex 144 is a vertex of the tongue portion 143 at the
first area portion 143a. In the section perpendicular to the rotational axis RS of the
impeller 2, the first vertex 144 is an intersection point of the curve line formed by the
tongue portion 143 and a bisector E11 of a first connection straight line LS11
connecting the central winding start portion 141a1 and the central connection portion
142f1. The first connection straight line LS11 and the bisector E11 intersect at a
right angle in the section perpendicular to the rotational axis RS of the shaft 2b. The
second vertex 145 is a vertex of the tongue portion 143 at the second area portion
143b. In the section perpendicular to the rotational axis RS of the impeller 2, the
second vertex 145 is an intersection point of the curve line 5 formed by the tongue
portion 143 and a bisector E12 of a second connection straight line LS12 connecting
the terminal winding start portion 141a2 and the terminal connection portion 142f2.
The second connection straight line LS12 and the bisector E12 intersect at a right
angle in the section perpendicular to the rotational axis RS of the shaft 2b.
[0046]
A virtual straight line connecting the rotational axis RS of the impeller 2 and the
first vertex 144 is defined as a first straight line L11. A virtual straight line connecting
the rotational axis RS of the impeller 2 and the second vertex 145 is defined as a
second straight line L12. In the centrifugal air-sending device 1A, the first straight
line L11 connecting the first vertex 144 and the rotational axis RS is shorter than the
second straight line L12 connecting the second vertex 145 and the rotational axis RS
in the section perpendicular to the rotational axis RS of the shaft 2b. In other words,
in the centrifugal air-sending device 1A, the second straight line L12 connecting the
second vertex 145 and the rotational axis RS is longer than the first straight line L11
connecting the first vertex 144 and the rotational axis RS in the section perpendicular
to the rotational axis RS of the shaft 2b. Therefore, the second vertex 145 of the
second area portion 143b is positioned farther away from the rotational axis RS than
is the first vertex 144 of the first area portion 143a. Thus, in the section
perpendicular to the rotational axis RS of the shaft 2b, the space between the impeller
2 and the tongue portion 143 is wider in the second area portion 143b than in the first
area portion 143a. As illustrated in Fig. 10, in the centrifugal air-sending device 1A,
the second vertex 145 is positioned closer to the discharge port end 42c1 than is the
first vertex 144 on the line between the rotational axis RS and the discharge port end
42c1 on the reference straight line T. In the tongue portion 143, the shortest
distance between the second vertex 145 and the reference straight line T is longer
than the shortest distance between the first vertex 144 and the reference straight line
T. Thus, in the section perpendicular to the rotational axis RS of the shaft 2b, the
space between the impeller 2 and the tongue portion 143 is wider in the second area
portion 143b than in the first area portion 143a.
5 [0047]
Fig. 13 is a side view of a modified example of the centrifugal air-sending
device 1A according to Embodiment 2 of the present disclosure that is viewed from
the discharge port 42a. Fig. 14 is a horizontal sectional view of a centrifugal airsending
device 11A of Fig. 13 at the part of the line B-B in Fig. 10. Although the
double-suction centrifugal air-sending device 1A is described with reference to Fig. 8
to Fig. 12, the centrifugal air-sending device 1A is not limited to the double-suction
centrifugal air-sending device 1A but may be a single-suction centrifugal air-sending
device 11A. Thus, the centrifugal air-sending device 11A is only required to have at
least one side wall 4a having the suction port 5. The scroll portion 41 of the
centrifugal air-sending device 11A includes the side wall 4a covering the impeller 2 in
the axial direction of the rotational axis RS of the shaft 2b of the impeller 2, and
having the suction port 5 through which air is suctioned, and the peripheral wall 4c
surrounding the impeller 2 in the radial direction of the rotational axis RS of the shaft
2b. The scroll portion 41 of the single-suction centrifugal air-sending device 11A
further includes the side wall 4d perpendicular to the axial direction of the rotational
axis RS. The side wall 4d has no suction port 5. The side wall 4d and the side wall
4a face each other. As illustrated in Fig. 13 and Fig. 14, the plurality of blades 2d of
the centrifugal air-sending device 11A are provided on one side of the main plate 2a
in the axial direction of the rotational axis RS of the shaft 2b.
[0048]
The tongue portion 143 includes the first area portion 143a facing the main
plate 2a in the direction parallel to the axial direction of the rotational axis RS of the
impeller 2, and the second area portion 143b positioned closer to the side wall 4a
than is the first area portion 143a. When the tongue portion 143 is viewed from the
discharge port 42a as illustrated in Fig. 13, the tongue portion 143 is curved such that
the first area portion 143a is positioned close to the rotational axis RS of the shaft 2b.
That is, in the centrifugal air-sending device 1A, when the tongue portion 143 is
viewed from the discharge port 42a, the first area portion 143a facing the main plate
2a is positioned closer to the rotational axis RS of the shaft 2b than is the second
area portion 143b connected to the side wall 4a having 5 the suction port 5. The
tongue portion 143 is formed such that the first area portion 143a facing the main
plate 2a and the second area portion 143b connected to the side wall 4a having the
suction port 5 are disposed on the same curve line when the tongue portion 143 is
viewed from the discharge port 42a. The first area portion 143a is a part of the
tongue portion 143 facing the main plate 2a of the impeller 2 and positioned close to
one end of the tongue portion 143 in the direction parallel to the axial direction of the
rotational axis RS of the shaft 2b. The second area portion 143b is a part of the
tongue portion 143 extending to the side wall 4a having the suction port 5 and
positioned close to the other end of the tongue portion 143 in the direction parallel to
the axial direction of the rotational axis RS of the shaft 2b. The first area portion
143a is a part of the tongue portion 143 positioned closer to the main plate 2a than is
the second area portion 143b. The second area portion 143b is a part of the tongue
portion 143 positioned closer to the suction port 5 than is the first area portion 143a.
The second area portion 143b may include not only the part of the tongue portion 143
extending to the side wall 4a having the suction port 5 but also a part of the tongue
portion 143 positioned closer to the side wall 4a than to the main plate 2a in the
direction parallel to the axial direction of the rotational axis RS of the shaft 2b.
[0049]
When the tongue portion 143 is viewed in a direction from the extension plate
42b to the diffuser plate 42c as illustrated in Fig. 14, the tongue portion 143 is curved
such that the first area portion 143a is positioned closer to the rotational axis RS of
the impeller 2 than is the second area portion 143b. In other words, when the
tongue portion 143 is viewed in the direction from the extension plate 42b to the
diffuser plate 42c, the tongue portion 143 is curved such that the second area portion
143b is positioned farther away from the rotational axis RS of the impeller 2 than is
the first area portion 143a. That is, the tongue portion 143 is smoothly curved such
that the tongue portion 143 is positioned gradually away from the impeller 2 and close
to the discharge port 42a with increasing distance from the first area portion 143a to
the second area portion 143b. Further, a part of the peripheral wall 4c extending to
the tongue portion 143 has a shape conforming to the shape 5 of the tongue portion
143. That is, the peripheral wall 4c is curved such that the part of the peripheral wall
4c is positioned gradually close to the rotational axis RS of the impeller 2 with
increasing distance from the side wall 4a to the main plate 2a. That is, the scroll
casing 4 is formed such that the part of the tongue portion 143positioned closer to the
side wall 4d and the part of the peripheral wall 4c extending to the tongue portion 143
and positioned closer to the side wall 4d in the axial direction of the rotational axis RS
of the impeller 2 are gently recessed inward of the scroll casing 4. Thus, the
peripheral wall 4c is curved in a shape conforming to the shape of the tongue portion
143. Compared with the centrifugal air-sending device 11, the centrifugal air-sending
device 11A is formed such that the second area portion 143b is positioned closer to
the extension plate 42b than is the first area portion 143a and bulges toward the
passage at the inflow port 42g more than does the first area portion 143a.
[0050]
[Operation of Centrifugal Air-sending Device 1A]
When the impeller 2 rotates, air outside the scroll casing 4 is suctioned into the
scroll casing 4 through the suction ports 5. The air suctioned into the scroll casing 4
is guided by the bell mouths 3 and suctioned into the impeller 2. The air suctioned
into the impeller 2 causes an air flow to which a dynamic pressure and a static
pressure are applied while the air passes through the plurality of blades 2d. The air
flow is blown radially outward from the impeller 2. While the air flow blown from the
impeller 2 is guided between the inner surface of the peripheral wall 4c and the
blades 2d in the scroll portion 41, the dynamic pressure is converted into a static
pressure. After the air flow blown from the impeller 2 passes through the scroll
portion 41, the air flow is blown out of the scroll casing 4 from the discharge port 42a
of the discharge portion 42 (arrow F2). The air flow blown from the impeller 2
concentrates at the main plate 2a. A part of the air flow blown from the main plate
2a impinges on the inner surface of the peripheral wall 4c of the scroll portion 41 and
flows toward the suction ports 5 along the peripheral wall 4c of the scroll portion 41.
The air flow around the main plate 2a and the air flow having flowed toward the
suction ports 5 are different in terms of their flow directions. 5 After the air flows are
guided between the inner surface of the peripheral wall 4c and the blades 2d in the
scroll portion 41 and pass through the scroll portion 41, a part of the air flows reenters
the scroll portion 41 with the tongue portion 143 as the border (arrow F3).
[0051]
[Advantageous Effects of Centrifugal Air-sending Device 1A]
As described above, the tongue portion 143 of the centrifugal air-sending
device 1A includes the first area portion 143a facing the main plate 2a in the direction
parallel to the axial direction of the rotational axis RS, and the second area portions
143b positioned closer to the respective side walls 4a than is the first area portion
143a. The first area portion 143a has the first vertex 144 in the section
perpendicular to the rotational axis RS. The first vertex 144 is the intersection point
of the curve line formed by the tongue portion 143 and the bisector E11 of the first
connection straight line LS11 connecting the winding start portion 141a and the
connection portion 142f, which is the end of the discharge portion 42. The second
area portion 143b has the second vertex 145, which is the intersection point of the
curve line formed by the tongue portion 143 and the bisector E12 of the second
connection straight line LS12 connecting the winding start portion 141a and the
connection portion 142f, which is the end of the discharge portion 42 closer to the
peripheral wall 4c than is the opposite end. When the virtual straight line connecting
the rotational axis RS and the first vertex 144 is defined as the first straight line L11
and the virtual straight line connecting the rotational axis RS and the second vertex
145 is defined as the second straight line L12, the second straight line L12 is longer
than the first straight line L11. With this structure of the tongue portion 143, a
stagnation point of air flows at the tongue portion 143 can be shifted depending on
the air flow around the main plate 2a and the air flow around the suction ports 5 that
are different in terms of their flow directions. As a result, it is possible to control, in
the centrifugal air-sending device 1A, the amount of the air flow that re-enters the
scroll portion 41 with the stagnation point of air flows as the border. Along with this,
local pressure fluctuation can be suppressed. Thus, noise can be reduced.
[0052]
The winding start portion 141a is positioned closer to the discharge port 42a
than is the virtual spiral curve 4c1 obtained by extending the curve of the spiral shape
in the direction opposite to the air flow direction. With this structure of the centrifugal
air-sending device 1A, the stagnation point of air flows at the tongue portion 143 can
be shifted depending on the air flow around the main plate 2a and the air flow around
the suction ports 5 that are different in terms of their flow directions. As a result, it is
possible to control, in the centrifugal air-sending device 1A, the amount of the air flow
that re-enters the scroll portion 41 with the stagnation point of air flows as the border.
Along with this, the local pressure fluctuation can be suppressed. Thus, noise can
be reduced.
[0053]
In the centrifugal air-sending device 1A, the angle between the first diffuser
portion 42c4 and the reference straight line T is defined as the first discharge port
angle 11 and the angle between the second diffuser portion 42c5 and the reference
straight line T is defined as the second discharge port angle 12. In this case, the
second discharge port angle 12 is larger than the first discharge port angle 11.
With this structure of the centrifugal air-sending device 1A, the stagnation point of air
flows at the tongue portion 143 can be shifted depending on the air flow around the
main plate 2a and the air flow around the suction ports 5 that are different in terms of
their flow directions. As a result, it is possible to control, in the centrifugal airsending
device 1A, the amount of the air flow that re-enters the scroll portion 41 with
the stagnation point of air flows as the border. Along with this, the local pressure
fluctuation can be suppressed. Thus, noise can be reduced.
[0054]
In the tongue portion 143, the second vertex 145 is positioned closer to the
discharge port end 42c1 than is the first vertex 144 on the line between the rotational
axis RS and the discharge port end 42c1 on the reference straight line T. With this
structure of the centrifugal air-sending device 1A, the stagnation point of air flows at
the tongue portion 143 can be shifted depending on the air 5 flow around the main plate
2a and the air flow around the suction ports 5 that are different in terms of their flow
directions. As a result, it is possible to control, in the centrifugal air-sending device
1A, the amount of the air flow that re-enters the scroll portion 41 with the stagnation
point of air flows as the border. Along with this, the local pressure fluctuation can be
suppressed. Thus, noise can be reduced.
[0055]
In the tongue portion 143, the shortest distance between the second vertex 145
and the reference straight line T is longer than the shortest distance between the first
vertex 144 and the reference straight line T. With this structure of the centrifugal air15
sending device 1A, the stagnation point of air flows at the tongue portion 143 can be
shifted depending on the air flow around the main plate 2a and the air flow around the
suction ports 5 that are different in terms of their flow directions. As a result, it is
possible to control, in the centrifugal air-sending device 1A, the amount of the air flow
that re-enters the scroll portion 41 with the stagnation point of air flows as the border.
Along with this, the local pressure fluctuation can be suppressed. Thus, noise can
be reduced.
[0056]
The tongue portion 143 is curved such that the first area portion 143a is
positioned close to the rotational axis RS when the tongue portion 143 is viewed from
the discharge port 42a. With this structure of the centrifugal air-sending device 1A,
the stagnation point of air flows at the tongue portion 143 can be shifted depending
on the air flow around the main plate 2a and the air flow around the suction ports 5
that are different in terms of their flow directions. As a result, it is possible to control,
in the centrifugal air-sending device 1A, the amount of the air flow that re-enters the
scroll portion 41 with the stagnation point of air flows as the border. Along with this,
the local pressure fluctuation can be suppressed. Thus, noise can be reduced.
[0057]
The tongue portion 143 is curved such that the second area portions 143b are
positioned farther away from the rotational axis RS than is the 5 first area portion 143a.
With this structure of the centrifugal air-sending device 1A, the stagnation point of air
flows at the tongue portion 143 can be shifted depending on the air flow around the
main plate 2a and the air flow around the suction ports 5 that are different in terms of
their flow directions. As a result, it is possible to control, in the centrifugal air10
sending device 1A, the amount of the air flow that re-enters the scroll portion 41 with
the stagnation point of air flows as the border. Along with this, the local pressure
fluctuation can be suppressed. Thus, noise can be reduced.
[0058]
Embodiment 3
Fig. 15 is a perspective view of a centrifugal air-sending device 1B according to
Embodiment 3 of the present disclosure. Fig. 16 is a side view of the centrifugal airsending
device 1B of Fig. 15 that is viewed from the discharge port 42a. Fig. 17 is a
sectional view of the centrifugal air-sending device 1B that is cut along a line A-A in
Fig. 16. Fig. 18 is a horizontal sectional view of the centrifugal air-sending device 1B
of Fig. 15 at a part of a line B-B on the centrifugal air-sending device 1B of Fig. 17.
Fig. 19 is a conceptual diagram illustrating a relationship between a tongue portion
243 and the rotational axis RS of the impeller 2 in the centrifugal air-sending device
1B of Fig. 15. Portions having the same structures as those of the centrifugal airsending
device 1 or the centrifugal air-sending device 1A of Fig. 1 to Fig. 12 are
represented by the same reference signs and description of the portions is omitted.
The centrifugal air-sending device 1B according to Embodiment 3 is different from the
centrifugal air-sending device 1 according to Embodiment 1 in terms of the structure
of the tongue portion 43. The structures of portions other than the tongue portion 43
are similar to the structures in the centrifugal air-sending device 1 according to
Embodiment 1. Thus, the following description is mainly directed to the structure of
the tongue portion 243 of the centrifugal air-sending device 1B according to
Embodiment 3 with reference to Fig. 15 to Fig. 19.
[0059]
(Tongue Portion 243)
The scroll casing 4 has the tongue portion 243 between 5 the diffuser plate 42c
of the discharge portion 42 and a winding start portion 241a of the peripheral wall 4c.
The tongue portion 243 introduces an air flow produced by the impeller 2 and passing
through the scroll portion 41 to the discharge port 42a. The tongue portion 243 is a
projection provided at the boundary between the scroll portion 41 and the discharge
portion 42. In the scroll casing 4, the tongue portion 243 extends in the direction
parallel to the axial direction of the rotational axis RS of the shaft 2b.
[0060]
As illustrated in Fig. 17, the tongue portion 243 is bent to project toward the
passage at the inflow port 42g of the discharge portion 42. The tongue portion 243
has a predetermined curvature radius and the peripheral wall 4c is smoothly
connected to the diffuser plate 42c via the tongue portion 243. When air passing
through the suction ports 5 and sent out from the impeller 2 is gathered by the scroll
casing 4 and flows into the discharge portion 42, the tongue portion 243 is of use as a
branch point in the passage. That is, the inflow port 42g of the discharge portion 42
has a passage of an air flow toward the discharge port 42a (arrow F2) and a passage
of an air flow that re-enters the upstream portion from the tongue portion 243 (arrow
F3). The air flow traveling toward the discharge portion 42 has a static pressure
increasing while the air flow is passing through the scroll casing 4. Therefore, the
pressure is higher than the pressure in the scroll casing 4. The tongue portion 243 is
thus configured to define the pressure difference, and is configured to introduce the
air traveling toward the discharge portion 42 to the individual passages by the curve
surface.
[0061]
The structure of the tongue portion 243 is further described with reference to
Fig. 16 to Fig. 19. The tongue portion 243 includes a first area portion 243a facing
the main plate 2a in the direction parallel to the axial direction of the rotational axis
RS of the impeller 2, and second area portions 243b positioned closer to the
respective side walls 4a than is the first area portion 243a. When the tongue portion
243 is viewed from the discharge port 42a as illustrated in Fig. 16, the tongue portion
243 is curved in a U-shape such that the first area portion 5 243a is positioned close to
the rotational axis RS of the shaft 2b. That is, in the centrifugal air-sending device
1B, when the tongue portion 243 is viewed from the discharge port 42a, the first area
portion 243a facing the main plate 2a is positioned closer to the rotational axis RS of
the shaft 2b than is the second area portions 243b connected to the respective side
walls 4a each having the suction port 5. The tongue portion 243 is formed such that
the first area portion 243a facing the main plate 2a and the second area portions
243b connected to the respective side walls 4a each having the suction port 5 are
disposed on the same curve line when the tongue portion 243 is viewed from the
discharge port 42a. The first area portion 243a is a part of the tongue portion 243
facing the main plate 2a of the impeller 2 and positioned at the center of the tongue
portion 243 in the direction parallel to the axial direction of the rotational axis RS of
the shaft 2b. The second area portion 243b is a part of the tongue portion 243
extending to each of the side walls 4a each having the suction port 5 and positioned
at each end of the tongue portion 243 in the direction parallel to the axial direction of
the rotational axis RS of the shaft 2b. The first area portion 243a is a part of the
tongue portion 243 positioned closer to the main plate 2a than are the second area
portions 243b. Each of the second area portions 243b is a part of the tongue portion
243 positioned closer to the corresponding suction port 5 than is the first area portion
243a. The second area portion 243b may include not only the part of the tongue
portion 243 extending to the side wall 4a having the suction port 5 but also a part of
the tongue portion 243 positioned closer to the side wall 4a than to the main plate 2a
in the direction parallel to the axial direction of the rotational axis RS of the shaft 2b.
[0062]
When the tongue portion 243 is viewed in a direction from the extension plate
42b to the diffuser plate 42c as illustrated in Fig. 18, a part of the tongue portion 243
closest to the impeller 2 has a straight shape parallel to the rotational axis RS of the
impeller 2. The first area portion 243a and the second area portions 243b of the
tongue portion 243 are positioned at equal distances from the rotational axis RS of
the impeller 2. That is, when the tongue portion 243 is viewed in the direction from
the extension plate 42b to the diffuser plate 42c as illustrated 5 in Fig. 18, the first area
portion 243a and the second area portions 243b at the part of the tongue portion 243
closest to the impeller 2 are disposed on the same straight line. In the centrifugal
air-sending device 1 according to Embodiment 1, the scroll casing 4 is formed such
that the center of the tongue portion 243 and the center of the part of the peripheral
wall 4c extending to the tongue portion 243 in the axial direction of the rotational axis
RS of the impeller 2 are gently recessed inward of the scroll casing 4. In the
centrifugal air-sending device 1B according to Embodiment 3, however, the peripheral
wall 4c is formed along a single curve surface without irregularities in the rotational
axis direction RS of the impeller 2 as illustrated in Fig. 17 and Fig. 19.
[0063]
The structure of the tongue portion 243 is described in more detail with
reference to Fig. 17 and Fig. 19. The tongue portion 243 is positioned between the
peripheral wall 4c and the diffuser plate 42c. The winding start portion 241a is
positioned at a boundary between the tongue portion 243 and the peripheral wall 4c
of the scroll portion 41. As illustrated in Fig. 17, in the section perpendicular to the
rotational axis RS of the shaft 2b, the winding start portion 241a is an inflection point
between a curve line of the tongue portion 243 and the curve line of the peripheral
wall 4c. A central winding start portion 241a1 is a winding start portion 241a at the
first area portion 243a. A terminal winding start portion 241a2 is a winding start
portion 241a at the second area portion 243b. Compared with the centrifugal airsending
device 1 according to Embodiment 1, the centrifugal air-sending device 1B is
formed such that each of the second area portions 243b is positioned closer to the
extension plate 42b than is the first area portion 243a and bulges toward the passage
at the inflow port 42g more than does the first area portion 243a. As described
above, the peripheral wall 4c has the spiral shape in the section perpendicular to the
rotational axis RS of the impeller 2. As illustrated in Fig. 19, in the section
perpendicular to the rotational axis RS of the shaft 2b, the winding start portion 241a
is positioned closer to the discharge port 42a than is the virtual spiral curve 4c1
obtained by extending the curve of the spiral shape in the direction opposite to the air
flow direction.
[0064]
A connection portion 242f is positioned at a boundary between the tongue
portion 243 and the diffuser plate 42c of the discharge portion 42. When the diffuser
plate 42c is a plate having a curve surface, the connection portion 242f is an inflection
point between the curve line of the tongue portion 243 and the curve line of the
diffuser plate 42c in the section perpendicular to the rotational axis RS of the shaft 2b.
When the diffuser plate 42c is a flat plate, as illustrated in Fig. 17, the connection
portion 242f, which is the end of the discharge portion 42 closer to the peripheral wall
4c than is the opposite end, is a boundary between the straight line of the diffuser
plate 42c and the curve line of the tongue portion 243 in the section perpendicular to
the rotational axis RS of the shaft 2b. A central connection portion 242f1 is a
connection portion 242f at the first area portion 243a. A terminal connection portion
242f2 is a connection portion 242f at the second area portion 243b. As illustrated in
Fig. 19, the central connection portion 242f1 and the terminal connection portion
242f2 are disposed at different positions in the section perpendicular to the rotational
axis RS of the shaft 2b. As illustrated in Fig. 17, the connection portion 242f
positioned at the boundary between the tongue portion 243 and the diffuser plate 42c
is an end of the tongue portion 243 and also the end of the diffuser plate 42c. In the
section perpendicular to the rotational axis RS of the shaft 2b, the first diffuser portion
42c4 having the central connection portion 242f1 as its end and the second diffuser
portion 42c5 having the terminal connection portion 242f2 as its end have different
discharge port angles. More specifically, in the section perpendicular to the
rotational axis RS of the shaft 2b, a virtual straight line connecting the rotational axis
RS of the shaft 2b and the discharge port end 42c1 of the diffuser plate 42c included
in the discharge port 42a is defined as the reference straight line T. An angle
between the first diffuser portion 42c4 and the reference straight line T is defined as a
first discharge port angle 21. An angle between the second diffuser portion 42c5
and the reference straight line T is defined as a second discharge port angle 22. In
the centrifugal air-sending device 1B, the second discharge port angle 22 of the
second diffuser portion 42c5 is larger than the first discharge 5 port angle 21 of the
first diffuser portion 42c4.
[0065]
As illustrated in Fig. 19, the tongue portion 243 has a first vertex 244 and a
second vertex 245. The first vertex 244 is a vertex of the tongue portion 243 at the
first area portion 243a. In the section perpendicular to the rotational axis RS of the
impeller 2, the first vertex 244 is an intersection point of the curve line formed by the
tongue portion 243 and a bisector E21 of a first connection straight line LS21
connecting the central winding start portion 241a1 and the central connection portion
242f1. The first connection straight line LS21 and the bisector E21 intersect at a
right angle in the section perpendicular to the rotational axis RS of the shaft 2b. The
second vertex 245 is a vertex of the tongue portion 243 at the second area portion
243b. In the section perpendicular to the rotational axis RS of the impeller 2, the
second vertex 245 is an intersection point of the curve line formed by the tongue
portion 243 and a bisector E22 of a second connection straight line LS22 connecting
the terminal winding start portion 241a2 and the terminal connection portion 242f2.
The second connection straight line LS22 and the bisector E22 intersect at a right
angle in the section perpendicular to the rotational axis RS of the shaft 2b.
[0066]
A virtual straight line connecting the rotational axis RS of the impeller 2 and the
first vertex 244 is defined as a first straight line L21. A virtual straight line connecting
the rotational axis RS of the impeller 2 and the second vertex 245 is defined as a
second straight line L22. In the centrifugal air-sending device 1B, the first straight
line L21 connecting the first vertex 244 and the rotational axis RS is shorter than the
second straight line L22 connecting the second vertex 245 and the rotational axis RS
in the section perpendicular to the rotational axis RS of the shaft 2b. In other words,
in the centrifugal air-sending device 1B, the second straight line L22 connecting the
second vertex 245 and the rotational axis RS is longer than the first straight line L21
connecting the first vertex 244 and the rotational axis RS in the section perpendicular
to the rotational axis RS of the shaft 2b. Therefore, the second vertex 245 of the
second area portion 243b is positioned farther away from 5 the rotational axis RS than
is the first vertex 244 of the first area portion 243a. Thus, in the section
perpendicular to the rotational axis RS of the shaft 2b, the space between the impeller
2 and the tongue portion 243 is wider in the second area portion 243b than in the first
area portion 243a. As illustrated in Fig. 17, in the centrifugal air-sending device 1B,
the second vertex 245 is positioned closer to the discharge port end 42c1 than is the
first vertex 244 on the line between the rotational axis RS and the discharge port end
42c1 on the reference straight line T. In the tongue portion 243, the shortest
distance between the second vertex 245 and the reference straight line T is longer
than the shortest distance between the first vertex 244 and the reference straight line
T. Thus, in the section perpendicular to the rotational axis RS of the shaft 2b, the
space between the impeller 2 and the tongue portion 243 is wider in the second area
portion 243b than in the first area portion 243a.
[0067]
Fig. 20 is a side view of a modified example of the centrifugal air-sending
device 1B according to Embodiment 3 of the present disclosure that is viewed from
the discharge port 42a. Fig. 21 is a horizontal sectional view of a centrifugal airsending
device 11B of Fig. 20 at the part of the line B-B in Fig. 17. Although the
double-suction centrifugal air-sending device 1B is described with reference to Fig. 15
to Fig. 19, the centrifugal air-sending device 1B is not limited to the double-suction
centrifugal air-sending device 1B but may be a single-suction centrifugal air-sending
device 11B. Thus, the centrifugal air-sending device 11B is only required to have at
least one side wall 4a having the suction port 5. The scroll portion 41 of the
centrifugal air-sending device 11B includes the side wall 4a covering the impeller 2 in
the axial direction of the rotational axis RS of the shaft 2b of the impeller 2, and
having the suction port 5 through which air is suctioned, and the peripheral wall 4c
surrounding the impeller 2 in the radial direction of the rotational axis RS of the shaft
2b. The scroll portion 41 of the single-suction centrifugal air-sending device 11B
further includes the side wall 4d perpendicular to the axial direction of the rotational
axis RS. The side wall 4d has no suction port 5. The side wall 4d and the side wall
4a face each other. As illustrated in Fig. 6 and Fig. 8, 5 the plurality of blades 2d of the
centrifugal air-sending device 11B are provided on one side of the main plate 2a in
the axial direction of the rotational axis RS of the shaft 2b.
[0068]
The tongue portion 243 includes the first area portion 243a facing the main
plate 2a in the direction parallel to the axial direction of the rotational axis RS of the
impeller 2, and the second area portion 243b positioned closer to the side wall 4a
than is the first area portion 243a. When the tongue portion 243 is viewed from the
discharge port 42a as illustrated in Fig. 20, the tongue portion 243 is curved such that
the first area portion 243a is positioned close to the rotational axis RS of the shaft 2b.
That is, in the centrifugal air-sending device 1B, when the tongue portion 243 is
viewed from the discharge port 42a, the first area portion 243a facing the main plate
2a is positioned closer to the rotational axis RS of the shaft 2b than is the second
area portion 243b connected to the side wall 4a having the suction port 5. The
tongue portion 243 is formed such that the first area portion 243a facing the main
plate 2a and the second area portion 243b connected to the side wall 4a having the
suction port 5 are disposed on the same curve line when the tongue portion 243 is
viewed from the discharge port 42a. The first area portion 243a is a part of the
tongue portion 243 facing the main plate 2a of the impeller 2 and positioned close to
one end of the tongue portion 243 in the direction parallel to the axial direction of the
rotational axis RS of the shaft 2b. The second area portion 243b is a part of the
tongue portion 243 extending to the side wall 4a having the suction port 5 and
positioned close to the other end of the tongue portion 243 in the direction parallel to
the axial direction of the rotational axis RS of the shaft 2b. The first area portion
243a is a part of the tongue portion 243 positioned closer to the main plate 2a than is
the second area portion 243b. The second area portion 243b is a part of the tongue
portion 243 positioned closer to the suction port 5 than is the first area portion 243a.
The second area portion 243b may include not only the part of the tongue portion 243
extending to the side wall 4a having the suction port 5 but also a part of the tongue
portion 243 positioned closer to the side wall 4a than to the main plate 2a in the
direction parallel to the axial direction of the 5 rotational axis RS of the shaft 2b.
[0069]
When the tongue portion 243 is viewed in a direction from the extension plate
42b to the diffuser plate 42c as illustrated in Fig. 21, a part of the tongue portion 243
closest to the impeller 2 has a straight shape parallel to the rotational axis RS of the
impeller 2. The first area portion 243a and the second area portion 243b of the
tongue portion 243 are positioned at equal distances from the rotational axis RS of
the impeller 2. That is, when the tongue portion 243 is viewed in the direction from
the extension plate 42b to the diffuser plate 42c, the first area portion 243a and the
second area portion 243b at the part of the tongue portion 243 closest to the impeller
2 are disposed on the same straight line. In the centrifugal air-sending device 11
described above, the scroll casing 4 is formed such that the part of the tongue portion
43positioned closer to the side wall 4d and the part of the peripheral wall 4c extending
to the tongue portion 43 and positioned closer to the side wall 4d in the axial direction
of the rotational axis RS of the impeller 2 are gently recessed inward of the scroll
casing 4. In the centrifugal air-sending device 11B, however, the peripheral wall 4c
is formed along a single curve surface without irregularities in the rotational axis
direction RS of the impeller 2 as illustrated in Fig. 20 and Fig. 21.
[0070]
[Operation of Centrifugal Air-sending Device 1B]
When the impeller 2 rotates, air outside the scroll casing 4 is suctioned into the
scroll casing 4 through the suction ports 5. The air suctioned into the scroll casing 4
is guided by the bell mouths 3 and suctioned into the impeller 2. The air suctioned
into the impeller 2 causes an air flow to which a dynamic pressure and a static
pressure are applied while the air passes through the plurality of blades 2d. The air
flow is blown radially outward from the impeller 2. While the air flow blown from the
impeller 2 is guided between the inner surface of the peripheral wall 4c and the
blades 2d in the scroll portion 41, the dynamic pressure is converted into a static
pressure. After the air flow blown from the impeller 2 passes through the scroll
portion 41, the air flow is blown out of the scroll casing 4 from the discharge port 42a
of the discharge portion 42 (arrow F2). The air flow blown 5 from the impeller 2
concentrates at the main plate 2a. A part of the air flow blown from the main plate
2a impinges on the inner surface of the peripheral wall 4c of the scroll portion 41 and
flows toward the suction ports 5 along the peripheral wall 4c of the scroll portion 41.
The air flow around the main plate 2a and the air flow having flowed toward the
10 suction ports 5 are different in terms of their flow directions. After the air flows are
guided between the inner surface of the peripheral wall 4c and the blades 2d in the
scroll portion 41 and pass through the scroll portion 41, a part of the air flows reenters
the scroll portion 41 with the tongue portion 243 as the border (arrow F3).
[0071]
[Advantageous Effects of Centrifugal Air-sending Device 1B]
As described above, the tongue portion 243 of the centrifugal air-sending
device 1B includes the first area portion 243a facing the main plate 2a in the direction
parallel to the axial direction of the rotational axis RS, and the second area portions
243b positioned closer to the respective side walls 4a than is the first area portion
243a. The first area portion 243a has the first vertex 244 in the section
perpendicular to the rotational axis RS. The first vertex 244 is the intersection point
of the curve line formed by the tongue portion 243 and the bisector E21 of the first
connection straight line LS21 connecting the winding start portion 241a and the
connection portion 242f, which is the end of the discharge portion 42. The second
area portion 243b has the second vertex 245, which is the intersection point of the
curve line formed by the tongue portion 243 and the bisector E22 of the second
connection straight line LS22 connecting the winding start portion 241a and the
connection portion 242f, which is the end of the discharge portion 42 closer to the
peripheral wall 4c than is the opposite end. When the virtual straight line connecting
the rotational axis RS and the first vertex 244 is defined as the first straight line L21
and the virtual straight line connecting the rotational axis RS and the second vertex
245 is defined as the second straight line L22, the second straight line L22 is longer
than the first straight line L21. With this structure of the tongue portion 243, a
stagnation point of air flows at the tongue portion 243 can be shifted depending on
the air flow around the main plate 2a and the air flow around 5 the suction ports 5 that
are different in terms of their flow directions. As a result, it is possible to control, in
the centrifugal air-sending device 1B, the amount of the air flow that re-enters the
scroll portion 41 with the stagnation point of air flows as the border. Along with this,
local pressure fluctuation can be suppressed. Thus, noise can be reduced.
[0072]
The winding start portion 241a is positioned closer to the discharge port 42a
than is the virtual spiral curve 4c1 obtained by extending the curve of the spiral shape
in the direction opposite to the air flow direction. With this structure of the centrifugal
air-sending device 1B, the stagnation point of air flows at the tongue portion 243 can be shifted depending on the air flow around the main plate 2a and the air flow around
the suction ports 5 that are different in terms of their flow directions. As a result, it is
possible to control, in the centrifugal air-sending device 1B, the amount of the air flow
that re-enters the scroll portion 41 with the stagnation point of air flows as the border.
Along with this, the local pressure fluctuation can be suppressed. Thus, noise can
be reduced.
[0073]
In the centrifugal air-sending device 1B, the angle between the first diffuser
portion 42c4 and the reference straight line T is defined as the first discharge port
angle 21 and the angle between the second diffuser portion 42c5 and the reference
straight line T is defined as the second discharge port angle 22. In this case, the
second discharge port angle 22 is larger than the first discharge port angle 21.
With this structure of the centrifugal air-sending device 1B, the stagnation point of air
flows at the tongue portion 243 can be shifted depending on the air flow around the
main plate 2a and the air flow around the suction ports 5 that are different in terms of
their flow directions. As a result, it is possible to control, in the centrifugal air48
sending device 1B, the amount of the air flow that re-enters the scroll portion 41 with
the stagnation point of air flows as the border. Along with this, the local pressure
fluctuation can be suppressed. Thus, noise can be reduced.
[0074]
In the tongue portion 243, the second vertex 245 5 is positioned closer to the
discharge port end 42c1 than is the first vertex 244 on the line between the rotational
axis RS and the discharge port end 42c1 on the reference straight line T. With this
structure of the centrifugal air-sending device 1B, the stagnation point of air flows at
the tongue portion 243 can be shifted depending on the air flow around the main plate
2a and the air flow around the suction ports 5 that are different in terms of their flow
directions. As a result, it is possible to control, in the centrifugal air-sending device
1B, the amount of the air flow that re-enters the scroll portion 41 with the stagnation
point of air flows as the border. Along with this, the local pressure fluctuation can be
suppressed. Thus, noise can be reduced.
[0075]
In the tongue portion 243, the shortest distance between the second vertex 245
and the reference straight line T is longer than the shortest distance between the first
vertex 244 and the reference straight line T. With this structure of the centrifugal airsending
device 1B, the stagnation point of air flows at the tongue portion 243 can be
shifted depending on the air flow around the main plate 2a and the air flow around the
suction ports 5 that are different in terms of their flow directions. As a result, it is
possible to control, in the centrifugal air-sending device 1B, the amount of the air flow
that re-enters the scroll portion 41 with the stagnation point of air flows as the border.
Along with this, the local pressure fluctuation can be suppressed. Thus, noise can
be reduced.
[0076]
The tongue portion 243 is curved such that the first area portion 243a is
positioned close to the rotational axis RS when the tongue portion 243 is viewed from
the discharge port 42a. With this structure of the centrifugal air-sending device 1B,
the stagnation point of air flows at the tongue portion 243 can be shifted depending
on the air flow around the main plate 2a and the air flow around the suction ports 5
that are different in terms of their flow directions. As a result, it is possible to control,
in the centrifugal air-sending device 1B, the amount of the air flow that re-enters the
scroll portion 41 with the stagnation point of air flows as the border. Along with this,
the local pressure fluctuation can be suppressed. Thus, 5 noise can be reduced.
[0077]
The tongue portion 243 is curved such that the second area portions 243b are
positioned farther away from the rotational axis RS than is the first area portion 243a.
With this structure of the centrifugal air-sending device 1B, the stagnation point of air
flows at the tongue portion 243 can be shifted depending on the air flow around the
main plate 2a and the air flow around the suction ports 5 that are different in terms of
their flow directions. As a result, it is possible to control, in the centrifugal airsending
device 1B, the amount of the air flow that re-enters the scroll portion 41 with
the stagnation point of air flows as the border. Along with this, the local pressure
fluctuation can be suppressed. Thus, noise can be reduced.
[0078]
Embodiment 4
Fig. 22 is a perspective view of a centrifugal air-sending device 1C according to
Embodiment 4 of the present disclosure. Fig. 23 is a side view of the centrifugal air20
sending device 1C of Fig. 22 that is viewed from the discharge port 42a. Fig. 24 is a
sectional view of the centrifugal air-sending device 1C that is cut along a line A-A in
Fig. 23. Fig. 25 is a horizontal sectional view of the centrifugal air-sending device 1C
of Fig. 22 at a part of a line B-B on the centrifugal air-sending device 1C of Fig. 24.
Fig. 26 is a conceptual diagram illustrating a relationship between a tongue portion
343 and the rotational axis RS of the impeller 2 in the centrifugal air-sending device
1C of Fig. 22. Portions having the same structures as those of the centrifugal airsending
device 1, the centrifugal air-sending device 1A, and the centrifugal airsending
device 1B of Fig. 1 to Fig. 19 are represented by the same reference signs
and description of the portions is omitted. The centrifugal air-sending device 1C
according to Embodiment 3 is different from the centrifugal air-sending device 1
according to Embodiment 1 in terms of the structure of the tongue portion 43. The
structures of portions other than the tongue portion 43 are similar to the structures in
the centrifugal air-sending device 1 according to Embodiment 1. Thus, the following
description is mainly directed to the structure of the tongue portion 343 of the
centrifugal air-sending device 1C according to Embodiment 5 4 with reference to Fig.
22 to Fig. 26.
[0079]
(Tongue Portion 343)
The scroll casing 4 has the tongue portion 343 between the diffuser plate 42c
10 of the discharge portion 42 and a winding start portion 341a of the peripheral wall 4c.
The tongue portion 343 introduces an air flow produced by the impeller 2 and passing
through the scroll portion 41 to the discharge port 42a. The tongue portion 343 is a
projection provided at the boundary between the scroll portion 41 and the discharge
portion 42. In the scroll casing 4, the tongue portion 343 extends in the direction
parallel to the axial direction of the rotational axis RS of the shaft 2b.
[0080]
As illustrated in Fig. 24, the tongue portion 343 is bent to project toward the
passage at the inflow port 42g of the discharge portion 42. The tongue portion 343
has a predetermined curvature radius and the peripheral wall 4c is smoothly
connected to the diffuser plate 42c via the tongue portion 343. When air passing
through the suction ports 5 and sent out from the impeller 2 is gathered by the scroll
casing 4 and flows into the discharge portion 42, the tongue portion 343 is of use as a
branch point in the passage. That is, the inflow port 42g of the discharge portion 42
has a passage of an air flow toward the discharge port 42a (arrow F2) and a passage
of an air flow that re-enters the upstream portion from the tongue portion 343 (arrow
F3). The air flow traveling toward the discharge portion 42 has a static pressure
increasing while the air flow is passing through the scroll casing 4. Therefore, the
pressure is higher than the pressure in the scroll casing 4. The tongue portion 343 is
thus configured to define the pressure difference, and is configured to introduce the
air traveling toward the discharge portion 42 to the individual passages by the curve
surface.
[0081]
The structure of the tongue portion 343 is further described with reference to
Fig. 23 to Fig. 26. The tongue portion 343 includes a 5 first area portion 343a facing
the main plate 2a in the direction parallel to the axial direction of the rotational axis
RS of the impeller 2, and second area portions 343b positioned closer to the
respective side walls 4a than is the first area portion 343a. When the tongue portion
343 is viewed from the discharge port 42a as illustrated in Fig. 23, the tongue portion
343 is curved in a U-shape such that the first area portion 343a is positioned close to
the rotational axis RS of the shaft 2b. That is, in the centrifugal air-sending device
1C, when the tongue portion 343 is viewed from the discharge port 42a, the first area
portion 343a facing the main plate 2a is positioned closer to the rotational axis RS of
the shaft 2b than is the second area portions 343b connected to the respective side
walls 4a each having the suction port 5. The tongue portion 343 is formed such that
the first area portion 343a facing the main plate 2a and the second area portions
343b connected to the respective side walls 4a each having the suction port 5 are
disposed on the same curve line when the tongue portion 343 is viewed from the
discharge port 42a. The first area portion 343a is a part of the tongue portion 343
facing the main plate 2a of the impeller 2 and positioned at the center of the tongue
portion 343 in the direction parallel to the axial direction of the rotational axis RS of
the shaft 2b. The second area portion 343b is a part of the tongue portion 343
extending to each of the side walls 4a each having the suction port 5 and positioned
at each end of the tongue portion 343 in the direction parallel to the axial direction of
25 the rotational axis RS of the shaft 2b. The first area portion 343a is a part of the
tongue portion 343 positioned closer to the main plate 2a than are the second area
portions 343b. Each of the second area portions 343b is a part of the tongue portion
343 positioned closer to the corresponding suction port 5 than is the first area portion
343a. The second area portion 343b may include not only the part of the tongue
portion 343 extending to the side wall 4a having the suction port 5 but also a part of
the tongue portion 343 positioned closer to the side wall 4a than to the main plate 2a
in the direction parallel to the axial direction of the rotational axis RS of the shaft 2b.
[0082]
When the tongue portion 343 is viewed in a direction from the extension plate
42b to the diffuser plate 42c as illustrated in Fig. 25, the tongue 5 portion 343 is curved
such that the first area portion 343a is positioned farther away from the rotational axis
RS of the impeller 2 than are the second area portions 343b. In other words, when
the tongue portion 343 is viewed in the direction from the extension plate 42b to the
diffuser plate 42c as illustrated in Fig. 25, the tongue portion 343 is curved such that
the second area portions 343b are positioned closer to the rotational axis RS of the
impeller 2 than is the first area portion 343a. That is, the tongue portion 343 has a
smooth inverted U-shape such that the tongue portion 343 is positioned gradually
close to the impeller 2 and away from the discharge port 42a with increasing distance
from the first area portion 343a to each of the second area portions 343b. As
illustrated in Fig. 24 and Fig. 26, a part of the peripheral wall 4c extending to the
tongue portion 343 has a shape conforming to the shape of the tongue portion 343.
That is, the peripheral wall 4c is curved such that the part of the peripheral wall 4c is
positioned gradually close to the rotational axis RS of the impeller 2 with increasing
distance from the main plate 2a to each of the side walls 4a. That is, the scroll
casing 4 is formed such that the center of the tongue portion 143 and the center of
the part of the peripheral wall 4c extending to the tongue portion 143 in the axial
direction of the rotational axis RS of the impeller 2 gently bulge from the inner surface
of the scroll casing 4. Thus, the peripheral wall 4c is curved in a shape conforming
to the shape of the tongue portion 343. Compared with the centrifugal air-sending
device 1 according to Embodiment 1, the centrifugal air-sending device 1C is formed
such that each of the second area portions 343b is positioned closer to the extension
plate 42b than is the first area portion 343a and bulges toward the passage at the
inflow port 42g more than does the first area portion 343a.
[0083]
The structure of the tongue portion 343 is described in more detail with
reference to Fig. 24 and Fig. 26. The tongue portion 343 is positioned between the
peripheral wall 4c and the diffuser plate 42c. The winding start portion 341a is
positioned at a boundary between the tongue portion 343 and the peripheral wall 4c
of the scroll portion 41. As illustrated in Fig. 24, in the 5 section perpendicular to the
rotational axis RS of the shaft 2b, the winding start portion 341a is an inflection point
between a curve line of the tongue portion 343 and the curve line of the peripheral
wall 4c. A central winding start portion 341a1 is a winding start portion 341a at the
first area portion 343a. A terminal winding start portion 341a2 is a winding start
portion 341a at the second area portion 343b. As described above, the peripheral
wall 4c has the spiral shape in the section perpendicular to the rotational axis RS of
the impeller 2. As illustrated in Fig. 26, in the section perpendicular to the rotational
axis RS of the shaft 2b, the winding start portion 341a is positioned closer to the
discharge port 42a than is the virtual spiral curve 4c1 obtained by extending the curve
of the spiral shape in the direction opposite to the air flow direction.
[0084]
A connection portion 342f is positioned at a boundary between the tongue
portion 343 and the diffuser plate 42c of the discharge portion 42. When the diffuser
plate 42c is a plate having a curve surface, the connection portion 342f is an inflection
point between the curve line of the tongue portion 343 and the curve line of the
diffuser plate 42c in the section perpendicular to the rotational axis RS of the shaft 2b.
When the diffuser plate 42c is a flat plate, as illustrated in Fig. 10, the connection
portion 342f, which is the end of the discharge portion 42 closer to the peripheral wall
4c than is the opposite end, is a boundary between the straight line of the diffuser
plate 42c and the curve line of the tongue portion 343 in the section perpendicular to
the rotational axis RS of the shaft 2b. A central connection portion 342f1 is a
connection portion 342f at the first area portion 343a. A terminal connection portion
342f2 is a connection portion 342f at the second area portion 343b. As illustrated in
Fig. 26, the central connection portion 342f1 and the terminal connection portion
342f2 are disposed at different positions in the section perpendicular to the rotational
axis RS of the shaft 2b. As illustrated in Fig. 24, the connection portion 342f
positioned at the boundary between the tongue portion 343 and the diffuser plate 42c
is an end of the tongue portion 343 and also the end of the diffuser plate 42c. In the
section perpendicular to the rotational axis RS of the shaft 2b, the first diffuser portion
42c4 having the central connection portion 342f1 as its end and 5 the second diffuser
portion 42c5 having the terminal connection portion 342f2 as its end have different
discharge port angles. More specifically, in the section perpendicular to the
rotational axis RS of the shaft 2b, a virtual straight line connecting the rotational axis
RS of the shaft 2b and the discharge port end 42c1 of the diffuser plate 42c included
in the discharge port 42a is defined as the reference straight line T. An angle
between the first diffuser portion 42c4 and the reference straight line T is defined as a
first discharge port angle 31. An angle between the second diffuser portion 42c5
and the reference straight line T is defined as a second discharge port angle 32. In
the centrifugal air-sending device 1C, the second discharge port angle 32 of the
second diffuser portion 42c5 is larger than the first discharge port angle 31 of the
first diffuser portion 42c4.
[0085]
As illustrated in Fig. 26, the tongue portion 343 has a first vertex 344 and a
second vertex 345. The first vertex 344 is a vertex of the tongue portion 343 at the
first area portion 343a. In the section perpendicular to the rotational axis RS of the
impeller 2, the first vertex 344 is an intersection point of the curve line formed by the
tongue portion 343 and a bisector E31 of a first connection straight line LS31
connecting the central winding start portion 341a1 and the central connection portion
342f1. The first connection straight line LS31 and the bisector E31 intersect at a
right angle in the section perpendicular to the rotational axis RS of the shaft 2b. The
second vertex 345 is a vertex of the tongue portion 343 at the second area portion
343b. In the section perpendicular to the rotational axis RS of the shaft 2b, the
second vertex 345 is an intersection point of the curve line formed by the tongue
portion 343 and a bisector E32 of a second connection straight line LS32 connecting
the terminal winding start portion 341a2 and the terminal connection portion 342f2.
55
In the section perpendicular to the rotational axis RS of the impeller 2, the second
vertex 345 is the intersection point of the curve line formed by the tongue portion 343
and the bisector E32 of the second connection straight line LS32 connecting the
terminal winding start portion 341a2 and the terminal connection portion 342f2. The
second connection straight line LS32 and the bisector E32 5 intersect at a right angle in
the section perpendicular to the rotational axis RS of the shaft 2b.
[0086]
A virtual straight line connecting the rotational axis RS of the impeller 2 and the
first vertex 344 is defined as a first straight line L31. A virtual straight line connecting
the rotational axis RS of the impeller 2 and the second vertex 345 is defined as a
second straight line L32. In the centrifugal air-sending device 1C, the first straight
line L31 connecting the first vertex 344 and the rotational axis RS is shorter than the
second straight line L32 connecting the second vertex 345 and the rotational axis RS
in the section perpendicular to the rotational axis RS of the shaft 2b. In other words,
in the centrifugal air-sending device 1C, the second straight line L32 connecting the
second vertex 345 and the rotational axis RS is longer than the first straight line L31
connecting the first vertex 344 and the rotational axis RS in the section perpendicular
to the rotational axis RS of the shaft 2b. Therefore, the second vertex 345 of the
second area portion 343b is positioned farther away from the rotational axis RS than
is the first vertex 344 of the first area portion 343a. Thus, in the section
perpendicular to the rotational axis RS of the shaft 2b, the space between the impeller
2 and the tongue portion 343 is wider in the second area portion 343b than in the first
area portion 343a. As illustrated in Fig. 24, in the tongue portion 343, the shortest
distance between the second vertex 345 and the reference straight line T is longer
than the shortest distance between the first vertex 344 and the reference straight line
T. Thus, in the section perpendicular to the rotational axis RS of the shaft 2b, the
space between the impeller 2 and the tongue portion 343 is wider in the second area
portion 343b than in the first area portion 343a.
[0087]
The centrifugal air-sending device 1C has the following relationship in the
section perpendicular to the rotational axis RS of the impeller 2. As illustrated in Fig.
, in the centrifugal air-sending device 1C, a distance between the central winding
start portion 341a1 and the impeller 2 on a virtual 5 connection straight line L131
connecting the central winding start portion 341a1 and the rotational axis RS is
defined as a first distance dB. In the centrifugal air-sending device 1C, a distance
between the terminal winding start portion 341a2 and the impeller 2 on a virtual
connection straight line L132 connecting the terminal winding start portion 341a2 and
the rotational axis RS is defined as a second distance dA. In the centrifugal airsending
device 1C, a distance between the impeller 2 and the peripheral wall 4c
extending to the first area portion 343a is defined as a first distance dB'. In the
centrifugal air-sending device 1C, a distance between the impeller 2 and the
peripheral wall 4c extending to the second area portion 343b is defined as a second
distance dA'. In this case, the centrifugal air-sending device 1C has a relationship of
second distance dA > first distance dB and a relationship of first distance dB' >
second distance dA'.
[0088]
Fig. 27 is a side view of a modified example of the centrifugal air-sending
device 1C according to Embodiment 4 of the present disclosure that is viewed from
the discharge port 42a. Fig. 28 is a horizontal sectional view of a centrifugal airsending
device 11C of Fig. 27 at the part of the line B-B in Fig. 24. Although the
double-suction centrifugal air-sending device 1C is described with reference to Fig. 22
to Fig. 26, the centrifugal air-sending device 1C is not limited to the double-suction
centrifugal air-sending device 1C but may be a single-suction centrifugal air-sending
device 11C. Thus, the centrifugal air-sending device 11C is only required to have at
least one side wall 4a having the suction port 5. The scroll portion 41 of the
centrifugal air-sending device 11C includes the side wall 4a covering the impeller 2 in
the axial direction of the rotational axis RS of the shaft 2b of the impeller 2, and
having the suction port 5 through which air is suctioned, and the peripheral wall 4c
surrounding the impeller 2 in the radial direction of the rotational axis RS of the shaft
2b. The scroll portion 41 of the single-suction centrifugal air-sending device 11C
further includes the side wall 4d perpendicular to the axial direction of the rotational
axis RS. The side wall 4d has no suction port 5. The side wall 4d and the side wall
4a face each other. As illustrated in Fig. 27 and Fig. 28, the 5 plurality of blades 2d of
the centrifugal air-sending device 11 are provided on one side of the main plate 2a in
the axial direction of the rotational axis RS of the shaft 2b.
[0089]
The tongue portion 343 includes the first area portion 343a facing the main
10 plate 2a in the direction parallel to the axial direction of the rotational axis RS of the
impeller 2, and the second area portion 343b positioned closer to the side wall 4a
than is the first area portion 343a. When the tongue portion 343 is viewed from the
discharge port 42a as illustrated in Fig. 27, the tongue portion 343 is curved such that
the first area portion 343a is positioned close to the rotational axis RS of the shaft 2b.
That is, in the centrifugal air-sending device 1C, when the tongue portion 343 is
viewed from the discharge port 42a, the first area portion 343a facing the main plate
2a is positioned closer to the rotational axis RS of the shaft 2b than is the second
area portion 343b connected to the side wall 4a having the suction port 5. The
tongue portion 343 is formed such that the first area portion 343a facing the main
plate 2a and the second area portion 343b connected to the side wall 4a having the
suction port 5 are disposed on the same curve line when the tongue portion 343 is
viewed from the discharge port 42a. The first area portion 343a is a part of the
tongue portion 343 facing the main plate 2a of the impeller 2 and positioned close to
one end of the tongue portion 343 in the direction parallel to the axial direction of the
rotational axis RS of the shaft 2b. The second area portion 343b is a part of the
tongue portion 343 extending to the side wall 4a having the suction port 5 and
positioned close to the other end of the tongue portion 343 in the direction parallel to
the axial direction of the rotational axis RS of the shaft 2b. The first area portion
343a is a part of the tongue portion 343 positioned closer to the main plate 2a than is
the second area portion 343b. The second area portion 343b is a part of the tongue
portion 343 positioned closer to the suction port 5 than is the first area portion 343a.
The second area portion 343b may include not only the part of the tongue portion 343
extending to the side wall 4a having the suction port 5 but also a part of the tongue
portion 343 positioned closer to the side wall 4a than to the main plate 2a in the
direction parallel to the axial direction of the 5 rotational axis RS of the shaft 2b.
[0090]
When the tongue portion 343 is viewed in a direction from the extension plate
42b to the diffuser plate 42c as illustrated in Fig. 28, the tongue portion 343 is curved
such that the first area portion 343a is positioned farther away from the rotational axis
RS of the impeller 2 than is the second area portion 343b. In other words, when the
tongue portion 343 is viewed in the direction from the extension plate 42b to the
diffuser plate 42c, the tongue portion 343 is curved such that the second area portion
343b is positioned closer to the rotational axis RS of the impeller 2 than is the first
area portion 343a. That is, the tongue portion 343 is smoothly curved such that the
tongue portion 343 is positioned gradually close to the impeller 2 and away from the
discharge port 42a with increasing distance from the first area portion 343a to the
second area portion 343b. Further, a part of the peripheral wall 4c extending to the
tongue portion 343 has a shape conforming to the shape of the tongue portion 343.
That is, the peripheral wall 4c is curved such that the part of the peripheral wall 4c is
positioned gradually close to the rotational axis RS of the impeller 2 with increasing
distance from the main plate 2a to the side wall 4a. That is, the scroll casing 4 is
formed such that the part of the tongue portion 143positioned closer to the side wall
4d and the part of the peripheral wall 4c extending to the tongue portion 143 and
positioned closer to the side wall 4d in the axial direction of the rotational axis RS of
the impeller 2 gently bulge from the inner surface of the scroll casing 4. Thus, the
peripheral wall 4c is curved in a shape conforming to the shape of the tongue portion
343. Compared with the centrifugal air-sending device 11, the centrifugal air-sending
device 11C is formed such that the second area portion 343b is positioned closer to
the extension plate 42b than is the first area portion 343a and bulges toward the
passage at the inflow port 42g more than does the first area portion 343a.
[0091]
[Operation of Centrifugal Air-sending Device 1C]
When the impeller 2 rotates, air outside the scroll casing 4 is suctioned into the
scroll casing 4 through the suction ports 5. The air suctioned 5 into the scroll casing 4
is guided by the bell mouths 3 and suctioned into the impeller 2. The air suctioned
into the impeller 2 causes an air flow to which a dynamic pressure and a static
pressure are applied while the air passes through the plurality of blades 2d. The air
flow is blown radially outward from the impeller 2. While the air flow blown from the
impeller 2 is guided between the inner surface of the peripheral wall 4c and the
blades 2d in the scroll portion 41, the dynamic pressure is converted into a static
pressure. After the air flow blown from the impeller 2 passes through the scroll
portion 41, the air flow is blown out of the scroll casing 4 from the discharge port 42a
of the discharge portion 42 (arrow F2). The air flow blown from the impeller 2
concentrates at the main plate 2a. A part of the air flow blown from the main plate
2a impinges on the inner surface of the peripheral wall 4c of the scroll portion 41 and
flows toward the suction ports 5 along the peripheral wall 4c of the scroll portion 41.
The air flow around the main plate 2a and the air flow having flowed toward the
suction ports 5 are different in terms of their flow directions. After the air flows are
guided between the inner surface of the peripheral wall 4c and the blades 2d in the
scroll portion 41 and pass through the scroll portion 41, a part of the air flows reenters
the scroll portion 41 with the tongue portion 343 as the border (arrow F3).
[0092]
[Advantageous Effects of Centrifugal Air-sending Device 1C]
As described above, the tongue portion 343 of the centrifugal air-sending
device 1C includes the first area portion 343a facing the main plate 2a in the direction
parallel to the axial direction of the rotational axis RS, and the second area portions
343b positioned closer to the respective side walls 4a than is the first area portion
343a. The first area portion 343a has the first vertex 344 in the section
perpendicular to the rotational axis RS. The first vertex 344 is the intersection point
of the curve line formed by the tongue portion 343 and the bisector E31 of the first
connection straight line LS31 connecting the winding start portion 341a and the
connection portion 342f, which is the end of the discharge portion 42. The second
area portion 343b has the second vertex 345, which is the intersection point of the
curve line formed by the tongue portion 343 and the bisector 5 E32 of the second
connection straight line LS32 connecting the winding start portion 341a and the
connection portion 342f, which is the end of the discharge portion 42 closer to the
peripheral wall 4c than is the opposite end. When the virtual straight line connecting
the rotational axis RS and the first vertex 344 is defined as the first straight line L31
and the virtual straight line connecting the rotational axis RS and the second vertex
345 is defined as the second straight line L32, the second straight line L32 is longer
than the first straight line L31. With this structure of the tongue portion 343, a
stagnation point of air flows at the tongue portion 343 can be shifted depending on
the air flow around the main plate 2a and the air flow around the suction ports 5 that
are different in terms of their flow directions. As a result, it is possible to control, in
the centrifugal air-sending device 1C, the amount of the air flow that re-enters the
scroll portion 41 with the stagnation point of air flows as the border. Along with this,
local pressure fluctuation can be suppressed. Thus, noise can be reduced.
[0093]
The winding start portion 341a is positioned closer to the discharge port 42a
than is the virtual spiral curve 4c1 obtained by extending the curve of the spiral shape
in the direction opposite to the air flow direction. With this structure of the centrifugal
air-sending device 1C, the stagnation point of air flows at the tongue portion 343 can
be shifted depending on the air flow around the main plate 2a and the air flow around
the suction ports 5 that are different in terms of their flow directions. As a result, it is
possible to control, in the centrifugal air-sending device 1C, the amount of the air flow
that re-enters the scroll portion 41 with the stagnation point of air flows as the border.
Along with this, the local pressure fluctuation can be suppressed. Thus, noise can
be reduced.
[0094]
In the centrifugal air-sending device 1C, the angle between the first diffuser
portion 42c4 and the reference straight line T is defined as the first discharge port
angle 31 and the angle between the second diffuser portion 42c5 and the reference
straight line T is defined as the second discharge port angle 32. In this case, the
second discharge port angle 32 is larger than the first 5 discharge port angle 31.
With this structure of the centrifugal air-sending device 1C, the stagnation point of air
flows at the tongue portion 343 can be shifted depending on the air flow around the
main plate 2a and the air flow around the suction ports 5 that are different in terms of
their flow directions. As a result, it is possible to control, in the centrifugal air10
sending device 1C, the amount of the air flow that re-enters the scroll portion 41 with
the stagnation point of air flows as the border. Along with this, the local pressure
fluctuation can be suppressed. Thus, noise can be reduced.
[0095]
In the tongue portion 343, the shortest distance between the second vertex 345
and the reference straight line T is longer than the shortest distance between the first
vertex 344 and the reference straight line T. With this structure of the centrifugal airsending
device 1C, the stagnation point of air flows at the tongue portion 343 can be
shifted depending on the air flow around the main plate 2a and the air flow around the
suction ports 5 that are different in terms of their flow directions. As a result, it is
possible to control, in the centrifugal air-sending device 1C, the amount of the air flow
that re-enters the scroll portion 41 with the stagnation point of air flows as the border.
Along with this, the local pressure fluctuation can be suppressed. Thus, noise can
be reduced.
[0096]
The tongue portion 343 is curved such that the first area portion 343a is
positioned close to the rotational axis RS when the tongue portion 343 is viewed from
the discharge port 42a. With this structure of the centrifugal air-sending device 1C,
the stagnation point of air flows at the tongue portion 343 can be shifted depending
on the air flow around the main plate 2a and the air flow around the suction ports 5
that are different in terms of their flow directions. As a result, it is possible to control,
in the centrifugal air-sending device 1C, the amount of the air flow that re-enters the
scroll portion 41 with the stagnation point of air flows as the border. Along with this,
the local pressure fluctuation can be suppressed. Thus, noise can be reduced.
[0097]
The centrifugal air-sending device 1C has the relationship of second distance
dA > first distance dB and the relationship of first distance dB' > second distance dA'.
With this structure of the tongue portion 343, the stagnation point of air flows at the
tongue portion 343 can be shifted depending on the air flow around the main plate 2a
10 and the air flow around the suction ports 5 that are different in terms of their flow
directions. As a result, it is possible to control, in the centrifugal air-sending device
1C, the amount of the air flow that re-enters the scroll portion 41 with the stagnation
point of air flows as the border. Along with this, the local pressure fluctuation can be
suppressed. Thus, noise can be reduced.
[0098]
The centrifugal air-sending device 1C has the relationship of second distance
dA > first distance dB and the relationship of first distance dB' > second distance dA'
and the tongue portion 343 is curved such that the first area portion 343a is
positioned farther away from the rotational axis RS than are the second area portions
343b. With this structure of the centrifugal air-sending device 1C, the stagnation
point of air flows at the tongue portion 343 can be shifted depending on the air flow
around the main plate 2a and the air flow around the suction ports 5 that are different
in terms of their flow directions. As a result, it is possible to control, in the centrifugal
air-sending device 1C, the amount of the air flow that re-enters the scroll portion 41
with the stagnation point of air flows as the border. Along with this, the local
pressure fluctuation can be suppressed. Thus, noise can be reduced.
[0099]
Embodiment 5
[Air-sending Apparatus 30]
Fig. 29 is a diagram illustrating the structure of an air-sending apparatus 30
according to Embodiment 5 of the present disclosure. Portions having the same
structures as those of the centrifugal air-sending device 1 and the other centrifugal
air-sending devices of Fig. 1 to Fig. 26 are represented by the same reference signs
and description of the portions is omitted. Examples of the 5 air-sending apparatus 30
according to Embodiment 5 include a ventilator and a desk fan. The air-sending
apparatus 30 includes the centrifugal air-sending device 1, the centrifugal air-sending
device 1A, the centrifugal air-sending device 1B, or the centrifugal air-sending device
1C according to the corresponding one of Embodiments 1 to 4, and a case 7 housing,
for example, the centrifugal air-sending device 1. In the following description, the
term "centrifugal air-sending device 1" refers to the centrifugal air-sending device 1,
the centrifugal air-sending device 1A, the centrifugal air-sending device 1B, or the
centrifugal air-sending device 1C according to the corresponding one of
Embodiments 1 to 4. The case 7 has two openings, which are a suction port 71 and
a discharge port 72. As illustrated in Fig. 29, the suction port 71 and the discharge
port 72 of the air-sending apparatus 30 face each other. The suction port 71 and the
discharge port 72 of the air-sending apparatus 30 need not essentially face each
other. For example, the suction port 71 or the discharge port 72 may be formed
above or below the centrifugal air-sending device 1. In the case 7, a space S1
including the suction port 71 and a space S2 including the discharge port 72 are
separated from each other by a partition plate 73. The centrifugal air-sending device
1 is installed with the suction ports 5 positioned in the space S1 including the suction
port 71 and the discharge port 42a positioned in the space S2 including the discharge
port 72.
[0100]
When the impeller 2 is driven to rotate by a motor 6 in the air-sending
apparatus 30, air is suctioned into the case 7 through the suction port 71. The air
suctioned into the case 7 is guided by the bell mouths 3 and suctioned into the
impeller 2. The air suctioned into the impeller 2 is blown radially outward from the
impeller 2. After the air blown from the impeller 2 passes through the scroll casing 4,
the air is blown from the discharge port 42a of the scroll casing 4 and then from the
discharge port 72 of the case 7.
[0101]
As the air-sending apparatus 30 according to 5 Embodiment 5 includes the
centrifugal air-sending device 1, the centrifugal air-sending device 1A, the centrifugal
air-sending device 1B, or the centrifugal air-sending device 1C according to the
corresponding one of Embodiments 1 to 4, noise can be reduced.
[0102]
Embodiment 6
[Air-conditioning Apparatus 40]
Fig. 30 is a perspective view of an air-conditioning apparatus 40 according to
Embodiment 6 of the present disclosure. Fig. 31 is a diagram illustrating the internal
structure of the air-conditioning apparatus 40 according to Embodiment 6 of the
present disclosure. Fig. 32 is a sectional view of the air-conditioning apparatus 40
according to Embodiment 6 of the present disclosure. In each centrifugal airsending
device 1 used in the air-conditioning apparatus 40 according to Embodiment
6, portions having the same structures as those of the centrifugal air-sending device 1
of Fig. 1 to Fig. 29 are represented by the same reference signs and description of
the portions is omitted. In Fig. 31, a top portion 16a is omitted for illustration of the
internal structure of the air-conditioning apparatus 40. The air-conditioning
apparatus 40 according to Embodiment 6 includes the centrifugal air-sending device
1, the centrifugal air-sending device 1A, the centrifugal air-sending device 1B, or the
centrifugal air-sending device 1C according to the corresponding one of
Embodiments 1 to 4, and a heat exchanger 10 facing the discharge port 42a of the
centrifugal air-sending device 1. The air-conditioning apparatus 40 according to
Embodiment 6 further includes a case 16 installed above a ceiling of an airconditioned
room. In the following description, the term "centrifugal air-sending
device 1" refers to the centrifugal air-sending device 1, the centrifugal air-sending
device 1A, the centrifugal air-sending device 1B, or the centrifugal air-sending device
1C according to the corresponding one of Embodiments 1 to 4.
[0103]
(Case 16)
As illustrated in Fig. 30, the case 16 has a cubic 5 shape including the top portion
16a, a bottom portion 16b, and side portions 16c. The shape of the case 16 is not
limited to the cubic shape but may be, for example, a columnar shape, a prism shape,
a conical shape, a shape including a plurality of corners, a shape including a plurality
of curves, or other shapes. The case 16 includes a side portion 16c having a case
discharge port 17 as one of the side portions 16c. As illustrated in Fig. 30, the shape
of the case discharge port 17 is a rectangular shape. The shape of the case
discharge port 17 is not limited to the rectangular shape but may be, for example, a
circular shape, an oval shape, or other shapes. The case 16 includes, as one of the
side portions 16c, a side portion 16c having a case suction port 18 that is opposite to
the side portion 16c having the case discharge port 17. As illustrated in Fig. 31, the
shape of the case suction port 18 is a rectangular shape. The shape of the case
suction port 18 is not limited to the rectangular shape but may be, for example, a
circular shape, an oval shape, or other shapes. A filter may be disposed to the case
suction port 18 to remove dust in air.
[0104]
The case 16 houses two centrifugal air-sending devices 1, a fan motor 9, and
the heat exchanger 10. Each centrifugal air-sending device 1 includes an impeller 2
and a scroll casing 4 having a bell mouth 3. The shape of the bell mouth 3 of the
centrifugal air-sending device 1 is similar to the shape of the bell mouth 3 of the
centrifugal air-sending device 1 of Embodiment 1. The fan motor 9 is supported by a
motor support 9a fixed to the top portion 16a of the case 16. The fan motor 9
includes an output shaft 6a. The output shaft 6a extends in parallel to the side
portion 16c having the case suction port 18 and the side portion 16c having the case
discharge port 17. As illustrated in Fig. 31, the two impellers 2 are attached to the
output shaft 6a in the air-conditioning apparatus 40. The impeller 2 forms a flow of
air suctioned into the case 16 from the case suction port 18 and blown to an airconditioned
space from the case discharge port 17. The number of the centrifugal
air-sending devices 1 disposed in the case 16 is not limited to two but may be one,
three, or more. When two or more centrifugal air-sending devices 1 are disposed,
the centrifugal air-sending devices 1 include one or more 5 centrifugal air-sending
devices out of the centrifugal air-sending device 1, the centrifugal air-sending device
1A, the centrifugal air-sending device 1B, and the centrifugal air-sending device 1C
according to Embodiments 1 to 4.
[0105]
As illustrated in Fig. 31, each centrifugal air-sending device 1 is attached to a
partition plate 19. The internal space of the case 16 is partitioned by the partition
plate 19 into a space S11, which is a suction portion of the scroll casing 4, and a
space S12, which is a discharge portion of the scroll casing 4.
[0106]
As illustrated in Fig. 32, the heat exchanger 10 faces a discharge port 42a of
each centrifugal air-sending device 1. In the case 16, the heat exchanger 10 is
disposed on an air passage of air discharged by the centrifugal air-sending device 1.
The heat exchanger 10 adjusts the temperature of air suctioned into the case 16 from
the case suction port 18 and to be blown to the air-conditioned space from the case
discharge port 17. The heat exchanger 10 may have a publicly known structure.
[0107]
When the impeller 2 rotates, air in the air-conditioned space is suctioned into
the case 16 through the case suction port 18. The air suctioned into the case 16 is
guided by the bell mouths 3 and suctioned into the corresponding impellers 2. The
air suctioned into each of the impellers 2 is blown radially outward from the impeller.
After the air blown from the impellers 2 passes through the scroll casing 4, the air is
blown from the discharge port 42a of the scroll casing 4 and supplied to the heat
exchanger 10. The air supplied to the heat exchanger 10 exchanges heat and the
temperature and humidity are adjusted while the air passes through the heat
exchanger 10. The air passing through the heat exchanger 10 is blown to the airconditioned
space from the case discharge port 17.
[0108]
As the air-conditioning apparatus 40 according to Embodiment 6 includes the
centrifugal air-sending device 1, the centrifugal air-sending device 5 1A, the centrifugal
air-sending device 1B, or the centrifugal air-sending device 1C according to the
corresponding one of Embodiments 1 to 4, noise can be reduced.
[0109]
Embodiment 7
[Refrigeration Cycle Apparatus 50]
Fig. 33 is a diagram illustrating the structure of a refrigeration cycle apparatus
according to Embodiment 7 of the present disclosure. For example, the
centrifugal air-sending device 1, the centrifugal air-sending device 1A, the centrifugal
air-sending device 1B, or the centrifugal air-sending device 1C according to the
corresponding one of Embodiments 1 to 4 is used for an indoor unit 200 of the
refrigeration cycle apparatus 50 according to Embodiment 7. Although the following
description is directed to a case where the refrigeration cycle apparatus 50 is used for
air conditioning, the purpose of use of the refrigeration cycle apparatus 50 is not
limited to air conditioning. For example, the refrigeration cycle apparatus 50 is used
for refrigeration or air conditioning as a refrigerator, a freezer, a vending machine, an
air-conditioning apparatus, a refrigeration apparatus, or a water heater.
[0110]
The refrigeration cycle apparatus 50 according to Embodiment 7 transfers heat
between outdoor air and indoor air via refrigerant to heat or cool a room, thereby
performing air conditioning. The refrigeration cycle apparatus 50 according to
Embodiment 7 includes an outdoor unit 100 and the indoor unit 200. In the
refrigeration cycle apparatus 50, a refrigerant circuit through which the refrigerant
circulates is formed by connecting the outdoor unit 100 and the indoor unit 200 by a
refrigerant pipe 300 and a refrigerant pipe 400. The refrigerant pipe 300 is a gas
pipe through which refrigerant in a gas phase flows. The refrigerant pipe 400 is a
liquid pipe through which refrigerant in a liquid phase flows. Two-phase gas-liquid
refrigerant may flow through the refrigerant pipe 400. In the refrigerant circuit of the
refrigeration cycle apparatus 50, a compressor 101, a flow switching device 102, an
outdoor heat exchanger 103, an expansion valve 105, and an indoor heat exchanger
201 are sequentially 5 connected via refrigerant pipes.
[0111]
(Outdoor Unit 100)
The outdoor unit 100 includes the compressor 101, the flow switching device
102, the outdoor heat exchanger 103, and the expansion valve 105. The
compressor 101 compresses suctioned refrigerant and discharges the compressed
refrigerant. The compressor 101 may include an inverter that changes an operation
frequency to change the capacity of the compressor 101. The capacity of the
compressor 101 is an amount of refrigerant sent out per unit time. Examples of the
flow switching device 102 include a four-way valve. The flow switching device 102
changes the direction of a refrigerant passage. The refrigeration cycle apparatus 50
can achieve a heating operation or a cooling operation by changing a flow of
refrigerant with the flow switching device 102 in accordance with an instruction from a
controller (not illustrated).
[0112]
The outdoor heat exchanger 103 exchanges heat between refrigerant and
outdoor air. During the heating operation, the outdoor heat exchanger 103 is used
as an evaporator and exchanges heat between outdoor air and low-pressure
refrigerant flowing into the outdoor heat exchanger 103 from the refrigerant pipe 400
to evaporate and gasify the refrigerant. During the cooling operation, the outdoor
heat exchanger 103 is used as a condenser and exchanges heat between outdoor air
and refrigerant compressed by the compressor 101 and flowing into the outdoor heat
exchanger 103 from the flow switching device 102 to condense and liquefy the
refrigerant. The outdoor heat exchanger 103 is provided with an outdoor air-sending
device 104 to increase the efficiency of the heat exchange between the refrigerant
and the outdoor air. The outdoor air-sending device 104 may be provided with an
inverter that changes an operation frequency of a fan motor to change the rotation
speed of a fan. The expansion valve 105 is an expansion device (flow rate control
unit). The flow rate control unit is used as the expansion valve by controlling the flow
rate of refrigerant flowing through the expansion valve 105. The expansion valve
105 regulates the pressure of refrigerant by changing 5 its opening degree. For
example, if the expansion valve 105 is an electronic expansion valve, the opening
degree is adjusted in accordance with an instruction from the controller (not
illustrated) or other devices.
[0113]
(Indoor Unit 200)
The indoor unit 200 includes the indoor heat exchanger 201 exchanges heat
between refrigerant and indoor air, and is provided with an indoor air-sending device
202 regulates a flow of air to be subjected to the heat exchange at the indoor heat
exchanger 201. During the heating operation, the indoor heat exchanger 201 is
used as a condenser and exchanges heat between indoor air and refrigerant flowing
into the indoor heat exchanger 201 from the refrigerant pipe 300 to condense and
liquefy the refrigerant. Then, the refrigerant flows out of the indoor heat exchanger
201 toward the refrigerant pipe 400. During the cooling operation, the indoor heat
exchanger 201 is used as an evaporator and exchanges heat between indoor air and
refrigerant having a low pressure through the expansion valve 105 so that the
refrigerant removes heat from the air. Thus, the refrigerant is evaporated and
gasified and then flows out of the indoor heat exchanger 201 toward the refrigerant
pipe 300. The indoor air-sending device 202 faces the indoor heat exchanger 201.
The centrifugal air-sending device 1, the centrifugal air-sending device 1A, the
centrifugal air-sending device 1B, or the centrifugal air-sending device 1C according
to the corresponding one of Embodiments 1 to 4 is applied to the indoor air-sending
device 202. The operation speed of the indoor air-sending device 202 is determined
by user settings. The indoor air-sending device 202 may be provided with an
inverter that changes an operation frequency of the fan motor (not illustrated) to
change the rotation speed of the impeller 2.
[0114]
[Examples of Operation of Refrigeration Cycle Apparatus 50]
Next, the cooling operation is described as an example of the operation of the
refrigeration cycle apparatus 50. High-temperature and high-pressure gas
refrigerant compressed and discharged by the compressor 101 5 flows into the outdoor
heat exchanger 103 via the flow switching device 102. The gas refrigerant flowing
into the outdoor heat exchanger 103 is condensed into low-temperature refrigerant by
exchanging heat with outdoor air sent by the outdoor air-sending device 104. The
low-temperature refrigerant flows out of the outdoor heat exchanger 103. The
refrigerant flowing out of the outdoor heat exchanger 103 is expanded by the
expansion valve 105 and the pressure is reduced to turn into low-temperature and
low-pressure two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant
flows into the indoor heat exchanger 201 of the indoor unit 200 and is evaporated into
low-temperature and low-pressure gas refrigerant by exchanging heat with indoor air
sent by the indoor air-sending device 202. The low-temperature and low-pressure
gas refrigerant flows out of the indoor heat exchanger 201. At this time, the indoor
air cooled by the refrigerant that removes heat from the indoor air becomes
conditioned air (blown air) and is blown into a room (air-conditioned space) from an
air outlet of the indoor unit 200. The gas refrigerant flowing out of the indoor heat
exchanger 201 is suctioned into the compressor 101 via the flow switching device 102
and is compressed again. The operation described above is repeated.
[0115]
Next, the heating operation is described as an example of the operation of the
refrigeration cycle apparatus 50. High-temperature and high-pressure gas
refrigerant compressed and discharged by the compressor 101 flows into the indoor
heat exchanger 201 of the indoor unit 200 via the flow switching device 102. The
gas refrigerant flowing into the indoor heat exchanger 201 is condensed into lowtemperature
refrigerant by exchanging heat with indoor air sent by the indoor airsending
device 202. The low-temperature refrigerant flows out of the indoor heat
exchanger 201. At this time, the indoor air heated by receiving heat from the gas
refrigerant becomes conditioned air (blown air) and is blown into the room (airconditioned
space) from the air outlet of the indoor unit 200. The refrigerant flowing
out of the indoor heat exchanger 201 is expanded by the expansion valve 105 and
the pressure is reduced to turn into low-temperature and low-pressure two-phase
gas-liquid refrigerant. The two-phase gas-liquid refrigerant 5 flows into the outdoor
heat exchanger 103 of the outdoor unit 100 and is evaporated into low-temperature
and low-pressure gas refrigerant by exchanging heat with outdoor air sent by the
outdoor air-sending device 104. The low-temperature and low-pressure gas
refrigerant flows out of the outdoor heat exchanger 103. The gas refrigerant flowing
out of the outdoor heat exchanger 103 is suctioned into the compressor 101 via the
flow switching device 102 and is compressed again. The operation described above
is repeated.
[0116]
As the refrigeration cycle apparatus 50 according to Embodiment 7 includes
the centrifugal air-sending device 1, the centrifugal air-sending device 1A, the
centrifugal air-sending device 1B, or the centrifugal air-sending device 1C according
to the corresponding one of Embodiments 1 to 4, noise can be reduced.
[0117]
The structures described in Embodiments 1 to 7 are illustrative of examples of
the present disclosure and may be combined with other publicly known technologies
or partially omitted or modified without departing from the spirit of the present
disclosure.
Reference Signs List
[0118]
1 centrifugal air-sending device 1A centrifugal air-sending device 1B
centrifugal air-sending device 1C centrifugal air-sending device 2 impeller 2a
main plate 2a1 peripheral edge 2b shaft 2c side plate 2d blade 2e
suction port 3 bell mouth 3a upstream end 3b downstream end 4 scroll
casing 4a side wall 4c peripheral wall 4c1 spiral curve 4d side wall 5
suction port 6 motor 6a output shaft 7 case 9 fan motor 9a motor
support 10 heat exchanger 11 centrifugal air-sending device 11A centrifugal
air-sending device 11B centrifugal air-sending device 11C centrifugal airsending
device 16 case 16a top portion 16b bottom portion 16c side
portion 17 case discharge port 18 case suction port 19 partition plate 30
air-sending apparatus 40 air-conditioning apparatus 5 41 scroll portion 41a
winding start portion 41a1 central winding start portion 41a2 terminal winding
start portion 41b winding end portion 42 discharge portion 42a discharge
port 42b extension plate 42c diffuser plate 42c1 discharge port end 42c4
first diffuser portion 42c5 second diffuser portion 42d first side plate 42e
second side plate42f connection portion 42f1 central connection portion 42f2
terminal connection portion 42g inflow port 43 tongue portion 43a first area
portion 43b second area portion 44 first vertex 45 second vertex 50
refrigeration cycle apparatus 71 suction port 72 discharge port 73 partition
plate 100 outdoor unit 101 compressor 102 flow switching device 103
outdoor heat exchanger 104 outdoor air-sending device 105 expansion valve
141a winding start portion 141a1 central winding start portion 141a2 terminal
winding start portion 142f connection portion 142f1 central connection portion
142f2 terminal connection portion 143 tongue portion 143a first area portion
143b second area portion 144 first vertex 145 second vertex 200 indoor
unit 201 indoor heat exchanger 202 indoor air-sending device 241a winding
start portion 241a1 central winding start portion 241a2 terminal winding start
portion 242f connection portion 242f1 central connection portion 242f2
terminal connection portion 243 tongue portion 243a first area portion 243b
second area portion 244 first vertex 245 second vertex 300 refrigerant pipe
341a winding start portion 341a1 central winding start portion 341a2 terminal
winding start portion 342f connection portion 342f1 central connection portion
342f2 terminal connection portion 343 tongue portion 343a first area portion
343b second area portion 344 first vertex 345 second vertex 400
refrigerant pipe

WE CLAIM:
[Claim 1]
A centrifugal air-sending device, comprising:
an impeller including a main plate having a disk shape and a plurality of blades
arranged on a peripheral edge 5 of the main plate; and
a scroll casing housing the impeller,
the scroll casing including
a discharge portion including a discharge port through which an air flow
produced by the impeller is discharged, and
a scroll portion including
at least one side wall covering the impeller in a direction perpendicular to an
axial direction of a rotational axis of the impeller and including a suction port through
which air is suctioned,
a peripheral wall surrounding the impeller in a direction parallel to the axial
direction of the rotational axis, and
a tongue portion forming a curve surface, positioned between an end of the
discharge portion and a winding start portion of the peripheral wall, and configured to
introduce the air flow produced by the impeller to the discharge port,
the tongue portion including
a first area portion facing the main plate in the direction parallel to the axial
direction of the rotational axis, and
a second area portion positioned closer to the at least one side wall than is the
first area portion,
in a section perpendicular to the rotational axis,
where the first area portion has a first vertex that is an intersection point of a
curve line formed by the tongue portion and a bisector of a first connection straight
line connecting the winding start portion and the end of the discharge portion,
the second area portion has a second vertex that is an intersection point of the
curve line formed by the tongue portion and a bisector of a second connection
straight line connecting the winding start portion and the end of the discharge portion,
a virtual straight line connecting the rotational axis and the first vertex is
defined as a first straight line, and
a virtual straight line connecting the rotational axis and the second vertex is
defined as a second straight line,
the second straight line being longer th 5 an the first straight line.
[Claim 2]
The centrifugal air-sending device of claim 1,
wherein the peripheral wall has a spiral shape in the section perpendicular to
the rotational axis, and
wherein the winding start portion is positioned closer to the discharge port than
is a virtual spiral curve obtained by extending a curve of the spiral shape in a direction
opposite to a direction of the air flow.
[Claim 3]
The centrifugal air-sending device of claim 1 or 2,
wherein the discharge portion includes
an extension plate extending to the peripheral wall, and
a diffuser plate extending to the tongue portion, facing the extension plate, and
positioned such that a sectional area of a passage gradually increases along an air
flow direction in the discharge portion,
wherein the diffuser plate includes
a first diffuser portion extending to the first area portion, and
a second diffuser portion extending to the second area portion, and
wherein, in the section perpendicular to the rotational axis,
where a virtual straight line connecting the rotational axis and a discharge port
end of the diffuser plate included in the discharge port is defined as a reference
straight line,
an angle between the first diffuser portion and the reference straight line is
defined as a first discharge port angle, and
an angle between the second diffuser portion and the reference straight line is
defined as a second discharge port angle,
the second discharge port angle is larger than the first discharge port angle.
[Claim 4]
The centrifugal air-sending device of claim 3, wherein the second vertex of the
tongue portion is positioned closer to the discharge port end than is the first vertex on
a line between the rotational axis and the discharge port end 5 on the reference straight
line.
[Claim 5]
The centrifugal air-sending device of claim 3 or 4, wherein, in the tongue
portion, a shortest distance between the second vertex and the reference straight line
is longer than a shortest distance between the first vertex and the reference straight
line.
[Claim 6]
The centrifugal air-sending device of any one of claims 1 to 5, wherein the
tongue portion is curved such that the first area portion is positioned close to the
rotational axis when the tongue portion is viewed from the discharge port.
[Claim 7]
The centrifugal air-sending device of any one of claims 1 to 6, wherein the
tongue portion is curved such that the second area portion is positioned farther away
from the rotational axis than is the first area portion.
[Claim 8]
The centrifugal air-sending device of any one of claims 1 to 6, wherein, in the
section perpendicular to the rotational axis,
where a distance between the winding start portion of the first area portion and
the impeller on a virtual connection straight line connecting the winding start portion of
the first area portion and the rotational axis is defined as a first distance dB,
a distance between the winding start portion of the second area portion and the
impeller on a virtual connection straight line connecting the winding start portion of the
second area portion and the rotational axis is defined as a second distance dA,
a distance between the impeller and the peripheral wall extending to the first
area portion is defined as a first distance dB', and
a distance between the impeller and the peripheral wall extending to the
second area portion is defined as a second distance dA',
the centrifugal air-sending device has a relationship of second distance dA >
first distance dB and a relationship of first distance dB' > second distance dA'.
[Claim 9]
The centrifugal air-sending device of claim 8, wherein the tongue portion is
curved such that the first area portion is positioned farther away from the rotational
axis than is the second area portion.
[Claim 10]
The centrifugal air-sending device of claim 7 or 9, wherein the peripheral wall is
curved in a shape conforming to a shape of the tongue portion.
[Claim 11]
The centrifugal air-sending device of any one of claims 1 to 10, wherein the
scroll portion includes one side wall as the at least one side wall.
[Claim 12]
The centrifugal air-sending device of any one of claims 1 to 10,
wherein the scroll portion includes two side walls as the at least one side wall,
and
wherein the two side walls face each other.
[Claim 13]
An air-sending apparatus, comprising:
the centrifugal air-sending device of any one of claims 1 to 12; and
a case housing the centrifugal air-sending device.
[Claim 14]
An air-conditioning apparatus, comprising:
the centrifugal air-sending device of any one of claims 1 to 12; and
a heat exchanger facing the discharge port of the centrifugal air-sending
device.
[Claim 15]
A refrigeration cycle apparatus, comprising the centrifugal air-sending device of
any one of claims 1 to 12.