FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
CENTRIFUGAL FAN, AIR-CONDITIONING 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 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION
AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

2
DESCRIPTION
Title of Invention
CENTRIFUGAL FAN, AIR-CONDITIONING APPARATUS, AND REFRIGERATION
CYCLE APPARATUS
5
Technical Field
[0001]
The present disclosure relates to a centrifugal fan including a scroll casing, an
air-conditioning apparatus including the centrifugal fan, and a refrigeration cycle
10 apparatus including the centrifugal fan.
Background Art
[0002]
In existing centrifugal fans, air blown out by rotation of an impeller flows, from
an inner end portion of a scroll peripheral wall having a volute shape to a discharge
15 port, in a casing whose scroll peripheral wall is expanded in a radial direction of the
impeller, and the air pressure thus increases. However, in terms of mounting such
an existing centrifugal fan in a unit, there sometimes arise restrictions on expansion of
a scroll peripheral wall in a radial direction. To address this, there has been
proposed a centrifugal fan in which the sectional area of a passage in a scroll casing
20 is increased with expansion of a scroll peripheral wall in a radial direction inhibited by
expanding a scroll side wall in the rotation axis direction of an impeller in addition to
expansion of the scroll peripheral wall in the radial direction (see, for example, Patent
Literature 1). In the centrifugal fan in Patent Literature 1, the scroll side wall is
gradually expanded from an inner end portion in the rotation direction of the impeller,
25 and the height of the scroll side wall is gradually reduced from a most expanded
portion in a direction toward the inner end portion. As a result, the centrifugal fan in
Patent Literature 1 is capable of smoothly guiding air flowing again to a tongue
portion in addition to achieving a pressure increase effect.
Citation List
30 Patent Literature
3
[0003]
Patent Literature 1: Japanese Unexamined Patent Application Publication No.
2007-127089
Summary of Invention
5 Technical Problem
[0004]
However, in the centrifugal fan in Patent Literature 1, the height of the scroll
side wall is reduced from the most expanded portion of the scroll side wall in the
direction toward the inner end portion, and the height of the part of the side wall
10 toward a discharge port is also reduced. Thus, the velocity of airflow may be
increased due to a reduction in the sectional area of the passage in the centrifugal fan
in Patent Literature 1 from the most expanded portion toward the discharge port.
Accordingly, there is a problem in that the airflow pressure cannot be efficiently
increased.
15 [0005]
The present disclosure is made to solve such a problem, and an object of the
present disclosure is to obtain a centrifugal fan, an air-conditioning apparatus, and a
refrigeration cycle apparatus that are capable of efficiently increasing airflow pressure
with a side wall expanded in the rotation axis direction of an impeller.
20 Solution to Problem
[0006]
A centrifugal fan according to an embodiment of the present disclosure
includes: an impeller having a back plate driven to rotate; and a scroll casing
including a peripheral wall provided in parallel with an axial direction of a rotation
25 shaft of the back plate to surround the impeller, and having a volute shape along a
rotation direction of the back plate, a first side wall extending along a first edge of the
peripheral wall, the first edge being at one end, in the axial direction of the rotation
shaft, of the peripheral wall, the first side wall facing a virtual extension of the back
plate, the virtual extension of the back plate being perpendicular to the rotation shaft,
30 the first side wall having a first air inlet defined therein and configured to let air in, and
4
a discharge port from which airflow generated by the impeller is discharged. The
scroll casing is configured such that an inner end portion of the volute shape of the
scroll casing, an expanded portion, and a first edge end portion are arranged in a
named order in the rotation direction, the first edge end portion being an end of a first
5 edge, defining the discharge port, of the first side wall, the first edge end portion being
farther from the rotation shaft than an other end of the first edge is to the rotation
shaft, and distance L1distance LM>distance LS is satisfied where LS is a distance
between the first side wall at the inner end portion of the volute shape and the virtual
extension of the back plate, LM is a distance between the first side wall at the
10 expanded portion and the virtual extension of the back plate, the expanded portion
being a portion at which the distance between the first side wall and the virtual
extension of the back plate is larger than LS, and L1 is a distance between the first
side wall at the first edge end portion and the virtual extension of the back plate.
[0007]
15 An air-conditioning apparatus according to another embodiment of the present
disclosure includes the centrifugal fan and a heat exchanger provided to face the
discharge port of the centrifugal fan.
[0008]
A refrigeration cycle apparatus according to still another embodiment of the
20 present disclosure includes the centrifugal fan.
Advantageous Effects of Invention
[0009]
According to the embodiments of the present disclosure, the scroll casing of
the centrifugal fan is configured such that the inner end portion, the expanded portion,
25 and the first edge end portion are arranged in a named order in the rotation direction
and such that distance L1distance LM>distance LS is satisfied. As a result, air
flowing in the scroll casing flows toward the discharge port with the pressure thereof
increasing along with expansion of the scroll side wall. In addition, part of the air
toward the inner end portion can smoothly flow again to the inner end portion due to
30 the height of the first side wall being reduced such that distance LM>distance LS is
5
satisfied. Furthermore, the scroll casing is configured such that distance
L1distance LM is satisfied. Thus, the scroll casing is configured without the
sectional area of the passage reduced from the expanded portion toward the
discharge port. Accordingly, the centrifugal fan, the air-conditioning apparatus, and
5 the refrigeration cycle apparatus having this configuration are capable of efficiently
increasing airflow pressure with expansion of the side wall.
Brief Description of Drawings
[0010]
[Fig. 1] Fig. 1 is a perspective view of a centrifugal fan according to
10 Embodiment 1.
[Fig. 2] Fig. 2 is a schematic diagram of the centrifugal fan according to
Embodiment 1 when viewed in a direction along a rotation shaft RS.
[Fig. 3] Fig. 3 is a sectional view of the centrifugal fan in Fig. 2 taken along line
S-M.
15 [Fig. 4] Fig. 4 is a side view of the centrifugal fan according to Embodiment 1
when viewed in a direction from a discharge port.
[Fig. 5] Fig. 5 is a perspective view of a scroll casing of the centrifugal fan
according to Embodiment 1.
[Fig. 6] Fig. 6 is a schematic diagram of the scroll casing in Fig. 5 when viewed
20 in the direction along the rotation shaft RS.
[Fig. 7] Fig. 7 is a graph illustrating a relationship between a scroll side wall
height H and an angle  in a scroll portion.
[Fig. 8] Fig. 8 is a graph illustrating a relationship between a scroll side wall
height H and an angle  in the scroll portion and a discharge portion.
25 [Fig. 9] Fig. 9 is a graph illustrating a relationship between a scroll side wall
height H and an angle  in a scroll portion of a modified scroll casing.
[Fig. 10] Fig. 10 is a schematic diagram of a centrifugal fan according to
Embodiment 2 when viewed in the direction along the rotation shaft RS.
[Fig. 11] Fig. 11 is a schematic diagram of a bulging portion of the centrifugal
30 fan in Fig. 10 when viewed from one side.
6
[Fig. 12] Fig. 12 is a graph illustrating a relationship between a scroll side wall
height H and an angle  in a scroll portion of the centrifugal fan according to
Embodiment 2.
[Fig. 13] Fig. 13 is a graph illustrating a relationship between a scroll side wall
5 height H and an angle  in another scroll portion of the centrifugal fan according to
Embodiment 2.
[Fig. 14] Fig. 14 is a schematic diagram for describing the effect of the bulging
portion.
[Fig. 15] Fig. 15 is a sectional view of a centrifugal fan according to
10 Embodiment 3 taken along line S-M corresponding to that in the centrifugal fan in Fig.
2.
[Fig. 16] Fig. 16 is a sectional view of a centrifugal fan according to
Embodiment 4 taken along line S-M corresponding to that in the centrifugal fan in Fig.
2.
15 [Fig. 17] Fig. 17 is a perspective view schematically illustrating an example of
an air-conditioning apparatus according to Embodiment 5.
[Fig. 18] Fig. 18 is a schematic diagram illustrating an example of the internal
configuration of the air-conditioning apparatus according to Embodiment 5.
[Fig. 19] Fig. 19 is a diagram illustrating the configuration of a refrigeration
20 cycle apparatus according to Embodiment 6.
Description of Embodiments
[0011]
A centrifugal fan 1 according to an embodiment of the present disclosure will be
described below with reference to the drawings, for example. In addition, an air25 conditioning apparatus 40 and a refrigeration cycle apparatus 50 according to
embodiments of the present disclosure will be described with reference to the
drawings, for example. For example, the relative size relationships or the shapes of
the components in the following drawings including Fig. 1 may differ from those of
actual ones. In the following drawings, components having the same reference
30 signs are the same or corresponding components, and this applies to the entire
7
description. Terms that mean directions (for example, "up", "down", "right", "left",
"forward", and "backward") are used as appropriate to make the description easy to
understand. However, these terms are merely used for convenience of description
and do not limit the dispositions and the orientations of apparatuses or components.
5 [0012]
Embodiment 1
[Centrifugal Fan 1]
Fig. 1 is a perspective view of the centrifugal fan 1 according to Embodiment 1.
Fig. 2 is a schematic diagram of the centrifugal fan 1 according to Embodiment 1
10 when viewed in a direction along a rotation shaft RS. Fig. 3 is a sectional view of the
centrifugal fan 1 in Fig. 2 taken along line S-M. Fig. 4 is a side view of the
centrifugal fan 1 according to Embodiment 1 when viewed in a direction from a
discharge port. The centrifugal fan 1 is a double suction centrifugal fan 1, into which
air is suctioned from both end sides thereof in the direction along the rotation shaft
15 RS of an impeller 2. A side opposite to the side of the centrifugal fan 1 illustrated in
Fig. 1 has a similar configuration. Thus, the configuration of the centrifugal fan 1 is
described by using Fig. 1, and the configuration of the side opposite to the side of the
centrifugal fan 1 in Fig. 1 is not illustrated.
[0013]
20 First, the basic structure of the centrifugal fan 1 will be described by using Figs.
1 to 4. The centrifugal fan 1 is, for example, a multiblade centrifugal fan 1, such as a
sirocco fan or a turbo fan. The centrifugal fan 1 includes the impeller 2, which is
configured to generate airflow, and a scroll casing 4, which accommodates the
impeller 2.
25 [0014]
(Impeller 2)
The impeller 2 is driven to rotate by, for example, a motor (not illustrated) and
forcibly sends air outward in radial directions with the centrifugal force generated by
the rotation. As illustrated in Figs. 1 and 2, the impeller 2 has a back plate 2a, which
30 has a disk shape, and a plurality of blades 2d, which are provided on a peripheral
8
portion 2a1 of the back plate 2a. The back plate 2a may have any shape, such as a
polygonal shape, other than a disk shape as long as the back plate 2a has a plate-like
shape. An axial portion 2b, to which the motor (not illustrated) is connected, is
provided at the center of the back plate 2a. The back plate 2a is driven to rotate by
5 the motor via the axial portion 2b.
[0015]
The blades 2d are provided on the circumference around the axial portion 2b.
The base ends of the blades 2d are fixed to the back plate 2a. The blades 2d are
provided on both sides of the back plate 2a in the axial direction of the rotation shaft
10 RS of the impeller 2. The blades 2d are provided on the peripheral portion 2a1 of
the back plate 2a with certain spaces therebetween. The blades 2d each have, for
example, a curved rectangular plate-like shape and are each provided to extend in a
radial direction or to be inclined at a predetermined angle relative to a radial direction.
The blades 2d are each formed into a two-dimensional blade in which the same
15 sectional shape is continuous in the axial direction of the rotation shaft RS but may be
each formed into a three-dimensional blade having a twisted shape. The blades 2d
are provided to stand substantially perpendicularly to the back plate 2a, but the
configuration thereof is not limited thereto. The blades 2d may be provided to be
inclined relative to a direction perpendicular to the back plate 2a.
20 [0016]
As illustrated in Figs. 3 and 4, the impeller 2 has side plates 2c, each of which
has an annular shape and is attached to the corresponding end portion opposite to
the back plate 2a of the blades 2d in the axial direction of the rotation shaft RS. The
side plates 2c maintain the positional relationship between the tips of the blades 2d
25 and reinforce the blades 2d by being connected to the blades 2d. Thus, one end of
each of the blades 2d is connected to the back plate 2a, the other end of each of the
blades 2d is connected to the corresponding side plate 2c, and the blades 2d are
provided between the back plate 2a and the side plates 2c.
[0017]
9
As illustrated in Fig. 1, the impeller 2 has a cylindrical shape due to the blades
2d provided on the back plate 2a. At respective positions closer to the side plates 2c
opposite to the back plate 2a in the axial direction of the rotation shaft RS, the
impeller 2 has air inlets 2e for allowing gas to flow therethrough into the spaces
5 surrounded by the back plate 2a and the blades 2d. In the impeller 2, the blades 2d
and the side plate 2c are provided at each side of the back plate 2a, and the air inlet
2e is formed at each side of the back plate 2a.
[0018]
The impeller 2 is driven to rotate around the rotation shaft RS by driving the
10 motor (not illustrated). By rotating the impeller 2, gas outside the centrifugal fan 1 is
suctioned into the spaces surrounded by the back plate 2a and the blades 2d through
air inlets 5, which are formed in the scroll casing 4, and the air inlets 2e of the impeller
2. By rotating the impeller 2, the air suctioned into the spaces surrounded by the
back plate 2a and the blades 2d is then sent outward in a radial direction through a
15 space between each blade 2d and the corresponding adjacent blade 2d.
[0019]
(Scroll Casing 4)
As illustrated in Fig. 1, the scroll casing 4 accommodates the impeller 2 and
rectifies the flow of air blown out from the impeller 2. The scroll casing 4 includes a
20 scroll portion 41 and a discharge portion 42.
[0020]
(Scroll Portion 41)
The scroll portion 41 defines an air passage in which the dynamic pressure of
airflow generated by the impeller 2 is converted into a static pressure. The scroll
25 portion 41 includes side walls 4a, which have the respective air inlets 5 defined
therein and configured to let air in and which surround the impeller 2 in the axial
direction of the rotation shaft RS of the axial portion 2b forming the impeller 2, and a
peripheral wall 4c, which surrounds the impeller 2 in radial directions of the rotation
shaft RS of the axial portion 2b forming the impeller 2. In addition, the scroll portion
30 41 includes a tongue portion 43, which has a curved surface between the discharge
10
portion 42 and an inner end portion 41s of the peripheral wall 4c and which is a
restriction portion required for blowing out, in a centrifugal direction, the air that has
flowed in through the air inlets 5 and increasing the air pressure. A radial direction of
the rotation shaft RS is a direction perpendicular to the rotation shaft RS. The
5 internal space of the scroll portion 41 formed by the peripheral wall 4c and the side
walls 4a is a space in which the air that has blown out from the impeller 2 flows along
the peripheral wall 4c.
[0021]
(Side Walls 4a)
10 As illustrated in Figs. 1 and 3, the side wall 4a is provided at each side of the
impeller 2 in the axial direction of the rotation shaft RS of the impeller 2. The side
walls 4a of the scroll casing 4 have the respective air inlets 5 for letting air in such that
air can flow between the impeller 2 and the outside of the scroll casing 4. The air
inlets 5 each have a circular shape. The impeller 2 is provided such that the center
15 of each of the air inlets 5 substantially coincides with the center of the axial portion 2b
of the impeller 2. The shape of the air inlet 5 is not limited to a circular shape and
may be a different shape such as an oval shape. The scroll casing 4 of the
centrifugal fan 1 is a double suction casing including the side wall 4a having the air
inlet 5 at each side of the back plate 2a in the axial direction of the rotation shaft RS
20 of the impeller 2. In the centrifugal fan 1, the scroll casing 4 includes two side walls
4a, and the side walls 4a are provided to face each other.
[0022]
As illustrated in Fig. 1, the scroll casing 4 includes, as the side walls 4a, a first
side wall 4a1 and a second side wall 4a2. The first side wall 4a1 extends along a
25 first edge 4c11 of the peripheral wall 4c, the first edge 4c11 being at one end, in the
axial direction of the rotation shaft RS, of the peripheral wall 4c, and the first side wall
4a1 faces a virtual extension L of the back plate 2a, the virtual extension L of the back
plate 2a being perpendicular to the rotation shaft RS. The second side wall 4a2
extends along a second edge 4c12 of the peripheral wall 4c, the second edge 4c12
30 being at the other end, in the axial direction of the rotation shaft RS, of the peripheral
11
wall 4c, and the second side wall 4a2 faces the extension L. As illustrated in Figs. 3
and 4, the first side wall 4a1 defines a first air inlet 5a, which faces the surface of the
back plate 2a closer to the position where a first side plate 2c1 is provided. The
second side wall 4a2 defines a second air inlet 5b, which faces the surface of the
5 back plate 2a closer to the position where a second side plate 2c2 is provided. The
term "air inlets 5" described above is a general term for the first air inlet 5a and the
second air inlet 5b.
[0023]
As illustrated in Figs. 1 and 2, the air inlets 5 provided in the respective side
10 walls 4a are formed by bell mouths 3. The bell mouths 3 rectify the flow of gas to be
suctioned into the impeller 2 and allow the gas to flow therethrough into the air inlets
2e of the impeller 2. As illustrated in Fig. 3, the bell mouths 3 are configured such
that the opening diameter is gradually reduced from the outside toward the inside of
the scroll casing 4. With the configuration of the side walls 4a, air near the air inlets
15 5 flows smoothly and efficiently into the impeller 2 from the air inlets 5.
[0024]
(Peripheral Wall 4c)
The peripheral wall 4c guides, along a curved wall surface thereof, airflow
generated by the impeller 2 to a discharge port 42a via the scroll portion 41. The
20 peripheral wall 4c is a wall provided between the side walls 4a facing each other and
has a curved surface in a rotation direction R of the impeller 2. For example, the
peripheral wall 4c is provided in parallel with the axial direction of the rotation shaft
RS of the impeller 2 to surround the impeller 2. The peripheral wall 4c may be
inclined relative to the axial direction of the rotation shaft RS of the impeller 2 and is
25 not limited to the peripheral wall 4c provided in parallel with the axial direction of the
rotation shaft RS. The peripheral wall 4c surrounds the impeller 2 in radial directions
of the rotation shaft RS and has an inner circumferential surface facing the blades 2d.
The peripheral wall 4c faces the air discharge sides of the blades 2d of the impeller 2.
As illustrated in Fig. 2, the peripheral wall 4c is provided to extend from the inner end
30 portion 41s positioned at the boundary between the peripheral wall 4c and the tongue
12
portion 43 to an outer end portion 41b positioned at the boundary between the scroll
portion 41 and the discharge portion 42 farther from the tongue portion 43 in the
rotation direction R of the impeller 2. The inner end portion 41s is an end portion of
the peripheral wall 4c having the curved surface, the end portion being upstream for
5 airflow generated by rotation of the impeller 2. The outer end portion 41b is an end
portion of the peripheral wall 4c having the curved surface, the end portion being
downstream for airflow generated by rotation of the impeller 2.
[0025]
The peripheral wall 4c has a volute shape along the rotation direction R.
10 Examples of such a volute shape include volute shapes based on a logarithmic spiral,
an Archimedean spiral, and an involute curve. The inner circumferential surface of
the peripheral wall 4c is a surface smoothly curved in the circumferential direction of
the impeller 2 from the inner end portion 41s, which is an inner end of the volute
shape, to the outer end portion 41b, which is an outer end of the volute shape. With
15 such a configuration, the air sent out from the impeller 2 flows smoothly between the
impeller 2 and the peripheral wall 4c in a direction toward the discharge portion 42.
Thus, in the scroll casing 4, the static pressure of air increases efficiently from the
tongue portion 43 toward the discharge portion 42.
[0026]
20 (Discharge Portion 42)
The discharge portion 42 defines the discharge port 42a from which the airflow
that has been generated by the impeller 2 and that has passed through the scroll
portion 41 is discharged. The discharge portion 42 is made of a hollow pipe whose
section orthogonal to a direction in which air flows along the peripheral wall 4c has a
25 rectangular shape. The discharge portion 42 defines a passage for guiding, to be
discharged to the outside of the scroll casing 4, the air that flows between the
peripheral wall 4c and the impeller 2 after being sent out from the impeller 2.
[0027]
As illustrated in Fig. 1, the discharge portion 42 is formed by an extended plate
30 42b, a diffuser plate 42c, the first side wall 4a1, and the second side wall 4a2. The
13
extended plate 42b is integrally formed with the peripheral wall 4c to be smoothly
continuous with the outer end portion 41b, which is downstream in the peripheral wall
4c. The diffuser plate 42c is integrally formed with the tongue portion 43 of the scroll
casing 4 and faces the extended plate 42b. The diffuser plate 42c is configured to
5 form a predetermined angle with the extended plate 42b such that the sectional area
of the passage increases gradually in the direction in which air flows in the discharge
portion 42. The extended plate 42b and the diffuser plate 42c are formed between
the first side wall 4a1 and the second side wall 4a2. In such a manner, the
discharge portion 42 has the passage whose section has a rectangular shape and
10 that is defined by the extended plate 42b, the diffuser plate 42c, the first side wall
4a1, and the second side wall 4a2.
[0028]
(Tongue Portion 43)
The scroll casing 4 has the tongue portion 43 between the diffuser plate 42c of
15 the discharge portion 42 and the inner end portion 41s of the peripheral wall 4c. The
tongue portion 43 is formed with a predetermined curvature radius. The peripheral
wall 4c is smoothly continuous with the diffuser plate 42c via the tongue portion 43.
The tongue portion 43 inhibits air from flowing from the outer end into the inner end of
the volute-shaped passage. The tongue portion 43 is provided in an upstream
20 section of the air passage and has a function of separating air flowing in the rotation
direction R of the impeller 2 and air flowing in the discharge direction from a
downstream section of the air passage toward the discharge port 42a. In addition,
the static pressure of air flowing into the discharge portion 42 increases during the air
passing through the scroll casing 4 and becomes higher than that in the scroll casing
25 4. Thus, the tongue portion 43 has a function of separating areas different from
each other in pressure as described above.
[0029]
(Specific Configuration of Scroll Casing 4)
Fig. 5 is a perspective view of the scroll casing 4 of the centrifugal fan 1
30 according to Embodiment 1. Fig. 6 is a schematic diagram of the scroll casing 4 in
14
Fig. 5 when viewed in the direction along the rotation shaft RS. The specific
configuration of the side walls 4a will be described by using Figs. 3 to 6.
[0030]
Here, as illustrated in Figs. 3, 5, and 6, a distance LS is the distance between
5 the first side wall 4a1 at the inner end portion 41s of the volute shape and the
extension L. An expanded portion 41m is a portion at which the distance between
the first side wall 4a1 and the extension L is larger than the distance LS. A distance
LM is the distance between the first side wall 4a1 at the expanded portion 41m and
the extension L. As illustrated in Fig. 6, the expanded portion 41m is formed
10 between, in the rotation direction R of the impeller 2, a position at 180 degrees
relative to the inner end portion 41s and a position where the line connecting the
rotation shaft RS and a first edge end portion 42a11 forms a first angle 1.
[0031]
Next, as illustrated in Figs. 4, 5, and 6, a distance L1 is the distance between
15 the first side wall 4a1 at the first edge end portion 42a11 and the extension L, the first
edge end portion 42a11 being an end of a first edge 42d, defining the discharge port
42a, of the first side wall 4a1, the first edge end portion 42a11 being farther from the
rotation shaft RS than the other end of the first edge 42d is to the rotation shaft RS.
A distance L2 is the distance between the first side wall 4a1 at a second edge end
20 portion 42a12 and the extension L, the second edge end portion 42a12 being the
other end of the first edge 42d, the second edge end portion 42a12 being closer to
the rotation shaft RS.
[0032]
The scroll casing 4 is configured such that the inner end portion 41s, the
25 expanded portion 41m, and the first edge end portion 42a11 are arranged in a named
order in the rotation direction R and such that distance L1distance LM>distance LS
is satisfied. Preferably, the scroll casing 4 is configured such that distance
L1distance L2distance LS is satisfied.
[0033]
15
Fig. 7 is a graph illustrating a relationship between a scroll side wall height H
and an angle  in the scroll portion 41. The relationship between a scroll side wall
height H and an angle  in the scroll portion 41 will be described by using Fig. 7.
The scroll side wall height H illustrated in Fig. 7 is a distance between the side wall 4a
5 and the extension L. The angle  is an angle, in the rotation direction R of the
impeller 2, whose starting point is the inner end portion 41s. As illustrated in Fig. 7,
the scroll casing 4 is configured such that the scroll side wall height H increases in the
rotation direction R from the inner end portion 41s to the expanded portion 41m.
Thus, the scroll casing 4 is configured such that the distance between the first side
10 wall 4a1 and the extension L gradually increases in the rotation direction R of the
impeller 2 from the inner end portion 41s toward the expanded portion 41m.
[0034]
In addition, as illustrated in Fig. 7, the scroll casing 4 is configured such that the
scroll side wall height H reduces in the rotation direction R from the expanded portion
15 41m to the inner end portion 41s. Thus, the scroll casing 4 is configured such that
the distance between the first side wall 4a1 and the extension L gradually reduces in
the rotation direction R of the impeller 2 from the expanded portion 41m toward the
inner end portion 41s.
[0035]
20 Fig. 8 is a graph illustrating a relationship between a scroll side wall height H
and an angle  in the scroll portion 41 and the discharge portion 42. The relationship
between a scroll side wall height H and an angle  in the scroll portion 41 and the
discharge portion 42 will be described by using Fig. 7. As illustrated in Fig. 8, the
scroll casing 4 is configured such that the scroll side wall height H increases in the
25 rotation direction R from the inner end portion 41s to the expanded portion 41m.
Thus, the scroll casing 4 is configured such that the distance between the first side
wall 4a1 and the extension L gradually increases in the rotation direction R of the
impeller 2 from the inner end portion 41s toward the expanded portion 41m.
[0036]
16
In addition, as illustrated in Fig. 8, the scroll casing 4 is configured such that the
scroll side wall height H is constant from the expanded portion 41m to the first edge
end portion 42a11. Thus, the scroll casing 4 is configured such that the distance
between the first side wall 4a1 and the extension L is constant from the expanded
5 portion 41m toward the first edge end portion 42a11.
[0037]
Furthermore, as represented by a dashed line DL in Fig. 8, the scroll casing 4
may be configured such that the scroll side wall height H increases from the
expanded portion 41m to the first edge end portion 42a11. Thus, the scroll casing 4
10 may be configured such that the distance between the first side wall 4a1 and the
extension L increases from the expanded portion 41m toward the first edge end
portion 42a11.
[0038]
As illustrated in Figs. 7 and 8, the scroll casing 4 is configured such that the
15 distance between the first side wall 4a1 and the extension L gradually increases in the
rotation direction R of the impeller 2 from the inner end portion 41s toward the
expanded portion 41m.
[0039]
Fig. 9 is a graph illustrating a relationship between a scroll side wall height H
20 and an angle  in a scroll portion 41 of a modified scroll casing 4. The configuration
from the expanded portion 41m toward the first edge end portion 42a11 in the
modified scroll casing 4 is the same as the configuration illustrated in Fig. 8.
[0040]
An expansion start portion 41p is a portion at which the distance between the
25 first side wall 4a1 and the extension L starts to increase in the rotation direction R of
the impeller 2. In the modified scroll casing 4, when the angle at the position of the
inner end portion 41s is 0 degrees, the expansion start portion 41p is formed between
a position at 0 degrees and a position at 180 degrees in the rotation direction R.
[0041]
17
Thus, the modified scroll casing 4 is configured such that the inner end portion
41s, the expansion start portion 41p, the expanded portion 41m, and the first edge
end portion 42a11 are arranged in a named order in the rotation direction R and such
that distance L1distance LM>distance LS is satisfied. Similarly to the scroll casing
5 4 described above, preferably, the modified scroll casing 4 is configured such that
distance L1distance L2distance LS is satisfied.
[0042]
The relationship between the first side wall 4a1 and the virtual extension L has
been described above. This relationship also applies to the relationship between the
10 second side wall 4a2 and the virtual extension L. Thus, as illustrated in Fig. 3, a
distance LS2 is the distance between the second side wall 4a2 at the inner end
portion 41s of the volute shape and the extension L. A second expanded portion
41m2 is a portion at which the distance between the second side wall 4a2 and the
extension L is larger than the distance LS2. A distance LM2 is the distance between
15 the second side wall 4a2 at the second expanded portion 41m2 and the extension L.
The second expanded portion 41m2 is formed between, in the rotation direction R of
the impeller 2, a position at 180 degrees relative to the inner end portion 41s and a
position where the line connecting the rotation shaft RS and a third edge end portion
42a21 forms a second angle 2. The second expanded portion 41m2 and the
20 expanded portion 41m may be formed at the same position or different positions in
the rotation direction R. That is, the first angle 1 and the second angle 2 may be
equal or unequal.
[0043]
Next, as illustrated in Fig. 4, a distance L3 is the distance between the second
25 side wall 4a2 at the third edge end portion 42a21 and the extension L, the third edge
end portion 42a21 being an end of a second edge 42e, defining the discharge port
42a, of the second side wall 4a2, the third edge end portion 42a21 being farther from
the rotation shaft RS than the other end of the second edge 42e is to the rotation
shaft RS. A distance L4 is the distance between the second side wall 4a2 at a fourth
30 edge end portion 42a22 and the extension L, the fourth edge end portion 42a22 being
18
the other end of the second edge 42e, the fourth edge end portion 42a22 being closer
to the rotation shaft RS.
[0044]
The scroll casing 4 is configured such that the inner end portion 41s, the
5 second expanded portion 41m2, and the third edge end portion 42a21 are arranged
in a named order in the rotation direction R and such that distance L3distance
LM2>distance LS2 is satisfied. Preferably, the scroll casing 4 is configured such that
distance L3distance L4distance LS2 is satisfied.
[0045]
10 The relationship between a scroll side wall height H and an angle  in the scroll
portion 41 illustrated in Figs. 7 and 8 also applies to the second side wall 4a2. Thus,
the scroll casing 4 is configured such that the scroll side wall height H increases in the
rotation direction R from the inner end portion 41s to the second expanded portion
41m2. That is, the scroll casing 4 is configured such that the distance between the
15 second side wall 4a2 and the extension L gradually increases in the rotation direction
R of the impeller 2 from the inner end portion 41s toward the second expanded
portion 41m2.
[0046]
In addition, the scroll casing 4 is configured such that the scroll side wall height
20 H reduces in the rotation direction R from the second expanded portion 41m2 to the
inner end portion 41s. Thus, the scroll casing 4 is configured such that the distance
between the second side wall 4a2 and the extension L gradually reduces in the
rotation direction R of the impeller 2 from the second expanded portion 41m2 toward
the inner end portion 41s.
25 [0047]
In addition, the scroll casing 4 is configured such that the scroll side wall height
H is constant from the second expanded portion 41m2 to the third edge end portion
42a21. Thus, the scroll casing 4 is configured such that the distance between the
second side wall 4a2 and the extension L is constant from the second expanded
30 portion 41m2 toward the third edge end portion 42a21.
19
[0048]
Furthermore, the scroll casing 4 may be configured such that the scroll side
wall height H increases from the second expanded portion 41m2 to the third edge end
portion 42a21. Thus, the scroll casing 4 may be configured such that the distance
5 between the second side wall 4a2 and the extension L increases from the second
expanded portion 41m2 toward the third edge end portion 42a21.
[0049]
Furthermore, in the modified scroll casing 4, when the angle at the position of
the inner end portion 41s in the second side wall 4a2 is 0 degrees, a second
10 expansion start portion 41p2 is formed between a position at 0 degrees and a position
at 180 degrees in the rotation direction R. The expansion start portion 41p in the
first side wall 4a1 and the second expansion start portion 41p2 in the second side
wall 4a2 are formed at the same position in the rotation direction R. However, the
configuration of the expansion start portion 41p in the first side wall 4a1 and the
15 second expansion start portion 41p2 in the second side wall 4a2 is not limited to the
configuration in which they are formed at the same position in the rotation direction R.
The expansion start portion 41p in the first side wall 4a1 and the second expansion
start portion 41p2 in the second side wall 4a2 may be formed at different positions in
the rotation direction R.
20 [0050]
[Operation Example of Centrifugal Fan 1]
When the impeller 2 rotates, air outside the scroll casing 4 is suctioned into the
scroll casing 4 through the air inlets 5 formed at the respective sides of the impeller 2.
In this case, the air suctioned into the scroll casing 4 is suctioned into the impeller 2
25 by being guided through the bell mouths 3. The air suctioned into the impeller 2
becomes, in the process of passing through the spaces between the blades 2d,
airflow to which a dynamic pressure and a static pressure are imparted, and the
airflow is blown out toward the outside of the impeller 2 in radial directions. The
dynamic pressure of the airflow blown out from the impeller 2 is converted into a static
30 pressure during the airflow being guided between the inside of the peripheral wall 4c
20
and the blades 2d in the scroll portion 41. After passing through the scroll portion
41, the airflow is blown outside the scroll casing 4 from the discharge port 42a formed
in the discharge portion 42. In this case, part of the airflow does not move toward
the discharge port 42a after passing through the scroll portion 41 but flows again into
5 the scroll portion 41 from the tongue portion 43.
[0051]
[Operation and Effect of Centrifugal Fan 1]
The scroll casing 4 of the centrifugal fan 1 is configured such that the inner end
portion 41s, the expanded portion 41m, and the first edge end portion 42a11 are
10 arranged in a named order in the rotation direction R and such that distance
L1distance LM>distance LS is satisfied. As a result, air flowing in the scroll casing
4 flows toward the discharge port 42a with the pressure thereof increasing due to an
increase in the sectional area of the passage along with expansion of the side wall
4a. In addition, part of the air toward the inner end portion 41s can smoothly flow
15 again to the inner end portion 41s due to the height of the first side wall 4a1 being
reduced such that distance LM>distance LS is satisfied. Furthermore, the scroll
casing 4 is configured such that distance L1distance LM is satisfied. Thus, the
scroll casing 4 is configured without the sectional area of the passage reduced from
the expanded portion 41m toward the discharge port 42a. Accordingly, the
20 centrifugal fan 1 having this configuration is capable of efficiently increasing airflow
pressure.
[0052]
In addition, the scroll casing 4 of the centrifugal fan 1 is configured such that
the inner end portion 41s, the second expanded portion 41m2, and the third edge end
25 portion 42a21 are arranged in a named order in the rotation direction R and such that
distance L3distance LM2>distance LS2 is satisfied. As a result, air flowing in the
scroll casing 4 flows toward the discharge port 42a with the pressure thereof
increasing due to an increase in the sectional area of the passage along with
expansion of the side wall 4a. In addition, part of the air toward the inner end portion
30 41s can smoothly flow again to the inner end portion 41s due to the height of the
21
second side wall 4a2 being reduced such that distance LM2>distance LS2 is
satisfied. Furthermore, the scroll casing 4 is configured such that distance
L3distance LM2 is satisfied. Thus, the scroll casing 4 is configured without the
sectional area of the passage reduced from the second expanded portion 41m2
5 toward the discharge port 42a. Accordingly, the centrifugal fan 1 having this
configuration is capable of efficiently increasing airflow pressure. In the centrifugal
fan 1, the first side wall 4a1 and the second side wall 4a2 each have the above
relationship. Thus, it is possible to make the configuration of the centrifugal fan 1
suitable, in terms of, for example, the air suction amount, for the form of a unit in
10 which the centrifugal fan 1 is to be mounted.
[0053]
In addition, in the scroll casing 4, the distance between the side wall 4a and the
extension L gradually increases in the rotation direction R from the inner end portion
41s toward the expanded portion 41m. Thus, in the centrifugal fan 1, the sectional
15 area of the passage in the scroll casing 4 can be increased with expansion thereof in
a radial direction inhibited.
[0054]
In addition, the expansion start portion 41p is formed between a position at 0
degrees and a position at 180 degrees in the rotation direction R. When the
20 centrifugal fan 1 has a configuration in which the side wall 4a is expanded, and the
amount of suction air flowing in from the vicinity of the inner end portion 41s is
excessively small, air may not flow sufficiently in the air passage formed between the
impeller 2 and the scroll casing 4. Thus, airflow separation occurs everywhere at an
inner wall surface of the scroll casing 4, and, actually, this configuration may reduce
25 efficiency. In the centrifugal fan 1, the expansion start portion 41p is formed between
a position at 0 degrees and a position at 180 degrees in the rotation direction R.
Thus, even when the amount of suction air flowing in from the vicinity of the inner end
portion 41s is excessively small, it is possible to start to expand the side wall 4a at a
position where there is a certain amount of suction air.
30 [0055]
22
In addition, the scroll casing 4 is configured such that distance L1distance
L2distance LS is satisfied, or the scroll casing 4 is configured such that distance
L3distance L4distance LS2 is satisfied. This configuration of the scroll casing 4
enables an excessive restriction of a discharge flow to be inhibited and enables an
5 airflow velocity increase effect to be reduced.
[0056]
In addition, the expanded portion 41m is formed between, in the rotation
direction R, a position at 180 degrees relative to the inner end portion 41s and a
position where the line connecting the rotation shaft RS and the first edge end portion
10 42a11 forms the first angle 1, or the second expanded portion 41m2 is formed
between, in the rotation direction R, a position at 180 degrees relative to the inner end
portion 41s and a position where the line connecting the rotation shaft RS and the
third edge end portion 42a21 forms the second angle 2. Thus, in the centrifugal fan
1, the sectional area of the passage in the scroll casing 4 can be increased with
15 expansion thereof in a radial direction inhibited. Accordingly, air flowing in the scroll
casing 4 flows toward the discharge port 42a with the pressure thereof increasing with
expansion of the side walls 4a.
[0057]
Embodiment 2
20 [Centrifugal Fan 1A]
Fig. 10 is a schematic diagram of a centrifugal fan 1A according to Embodiment
2 when viewed in the direction along the rotation shaft RS. Fig. 11 is a schematic
diagram of a bulging portion 14 of the centrifugal fan 1A in Fig. 10 when viewed from
one side. Components having the same configurations as those of the components
25 of the centrifugal fan 1 in Figs. 1 to 9 have the same reference signs, and the
descriptions thereof are omitted. The centrifugal fan 1A according to Embodiment 2
differs from the centrifugal fan 1 according to Embodiment 1 in the shape of the side
wall 4a. Thus, the configuration of the side wall 4a of the centrifugal fan 1A
according to Embodiment 2 will be mainly described below by using Figs. 10 and 11.
23
Outline arrows FL illustrated in Fig. 10 represent flows of a large amount of suction
air.
[0058]
As illustrated in Figs. 10 and 14, the side wall 4a has the bulging portion 14.
5 The bulging portion 14 is a portion of the side wall 4a bulging toward a side opposite
to the extension L. The bulging portion 14 is formed between the inner end portion
41s and the expanded portion 41m in the rotation direction R. As illustrated in Fig.
10, the bulging portions 14 are formed at respective positions where a large amount
of suction air flows in. The bulging portion 14 is formed to extend in a radial direction
10 of the rotation shaft RS.
[0059]
The bulging portion 14 may be formed at one of the first side wall 4a1 and the
second side wall 4a2 or at each of the first side wall 4a1 and the second side wall
4a2. In addition, the position, in the rotation direction R from the inner end portion
15 41s, where the bulging portion 14 is formed at the first side wall 4a1 and the position,
in the rotation direction R from the inner end portion 41s, where the bulging portion 14
is formed at the second side wall 4a2 may be the same or different.
[0060]
Fig. 12 is a graph illustrating a relationship between a scroll side wall height H
20 and an angle  in a scroll portion 41 of the centrifugal fan 1A according to
Embodiment 2. Fig. 13 is a graph illustrating a relationship between a scroll side
wall height H and an angle  in another scroll portion 41 of the centrifugal fan 1A
according to Embodiment 2. As illustrated in Figs. 12 and 13, the bulging portion 14
is a portion at which a predetermined rate of change at which the scroll side wall
25 height H increases from the inner end portion 41s to the expanded portion 41m partly
changes. The bulging portion 14 is formed according to a locally increased amount
of suction air. As illustrated in Figs. 12 and 13, the number of the bulging portions 14
to be formed may be one or more than one. In addition, as illustrated in Figs. 10 and
11, the bulging portion 14 may also be formed at the bell mouth 3. Furthermore,
30 although Fig. 10 illustrates the form in which the bulging portion 14 is formed
24
throughout a part of the first side wall 4a1 (side wall 4a) in a radial direction, the
bulging portion 14 may be formed only in a part of a region of a part of the first side
wall 4a1 (side wall 4a) in a radial direction. Similarly, the bulging portion 14 may be
formed only in a part of a region of a part of the second side wall 4a2 (side wall 4a) in
5 a radial direction.
[0061]
[Operation and Effect of Centrifugal Fan 1A]
Fig. 14 is a schematic diagram for describing the effect of the bulging portion
14. In Fig. 14, the centrifugal fan 1A according to Embodiment 2 is provided in a unit
10 30. The centrifugal fan 1A is provided between walls 31 of the unit 30. Air
nonuniformly flows into the centrifugal fan 1A mounted in the unit 30 due to an air
passage in the unit 30. When Fig. 14 is taken as an example, air flows in a direction
from the left, and the amount of suction air thus tends to increase at a position at 180
degrees relative to the inner end portion 41s in the rotation direction R. For this
15 reason, when the side wall 4a expands in the direction along the rotation shaft RS at
a constant rate of expansion, the velocity of airflow may be increased in an air
passage formed between the impeller 2 and the scroll casing due to insufficient
expansion of the side wall 4a. The bulging portion 14 is provided in a suction
direction, and the passage is expanded by partly changing the rate of expansion of
20 the side wall 4a in the direction along the rotation shaft RS. As a result, the
centrifugal fan 1A is capable of inhibiting an increase in the velocity of airflow and
efficiently performing conversion into a pressure.
[0062]
Embodiment 3
25 [Centrifugal Fan 1B]
Fig. 15 is a sectional view of a centrifugal fan 1B according to Embodiment 3
taken along line S-M corresponding to that in the centrifugal fan 1 in Fig. 2.
Components having the same configurations as those of the components of the
centrifugal fan 1 and another centrifugal fan in Figs. 1 to 14 have the same reference
30 signs, and the descriptions thereof are omitted. The centrifugal fan 1B according to
25
Embodiment 3 differs from the centrifugal fan 1 according to Embodiment 1 in the
shape of the second side wall 4a2. Thus, the configuration of the side wall 4a of the
centrifugal fan 1B according to Embodiment 3 will be mainly described below by using
Fig. 15.
5 [0063]
The scroll casing 4 of the centrifugal fan 1B according to Embodiment 3
includes a second side wall 4a21 extending along the second edge 4c12 of the
peripheral wall 4c, the second edge 4c12 being at the other end, in the axial direction
of the rotation shaft RS, of the peripheral wall 4c, the second side wall 4a21 facing
10 the extension L, the second side wall 4a21 having the second air inlet 5b defined
therein and configured to let air in. A distance LM21 is the distance between the
second side wall 4a21 at the second expanded portion 41m2 and the extension L. A
distance LS21 is the distance between the second side wall 4a21 at the inner end
portion 41s of the volute shape and the extension L. The centrifugal fan 1B has the
15 relationship that the distance LM21 is substantially equal to the distance LS21. That
is, the distance between the second side wall 4a21 and the extension L is
substantially constant in the rotation direction R. In the centrifugal fan 1B, the
feature in which the side wall 4a is expanded in the direction along the rotation shaft
RS is applied only to the first side wall 4a1. The centrifugal fan 1B includes the
20 scroll casing 4 whose respective suction sides have different shapes.
[0064]
[Operation and Effect of Centrifugal Fan 1B]
When the centrifugal fan 1 according to Embodiment 1 is mounted in a unit,
and, for example, an obstacle exists at one of the side walls 4a, the respective
25 amounts of air suctioned by the left side and the right side of the centrifugal fan 1 are
different from each other. In this case, when the feature in which the side wall 4a is
expanded in the direction along the rotation shaft RS is applied to the side wall 4a at
which the amount of suction air is small, the passage in the scroll casing 4 of the
centrifugal fan 1 is expanded excessively to be out of proportion to the amount of air.
30 In this case, airflow separation may occur at the inner wall surface of the scroll casing
26
4 of the centrifugal fan 1. On the other hand, in the centrifugal fan 1B, the distance
between the second side wall 4a21 and the extension L is constant in the rotation
direction R. In the centrifugal fan 1B, application of the second side wall 4a21 to the
side wall 4a at which the amount of suction air is small enables the passage in the
5 scroll casing 4 to have an area appropriate for the amount of air. As a result, the
centrifugal fan 1B is capable of inhibiting airflow separation from occurring at the inner
wall surface of the scroll casing 4.
[0065]
Embodiment 4
10 [Centrifugal Fan 1C]
Fig. 16 is a sectional view of a centrifugal fan 1C according to Embodiment 4
taken along line S-M corresponding to that in the centrifugal fan 1 in Fig. 2.
Components having the same configurations as those of the components of the
centrifugal fan 1 and other centrifugal fans in Figs. 1 to 15 have the same reference
15 signs, and the descriptions thereof are omitted. The centrifugal fan 1C according to
Embodiment 4 differs from the centrifugal fan 1 according to Embodiment 1 in the
shape of the second side wall 4a2. Thus, the configuration of the side wall 4a of the
centrifugal fan 1C according to Embodiment 4 will be mainly described below by
using Fig. 16.
20 [0066]
The scroll casing 4 of the centrifugal fan 1C according to Embodiment 4
includes a second side wall 4a23 extending along the second edge 4c12 of the
peripheral wall 4c, the second edge 4c12 being at the other end, in the axial direction
of the rotation shaft RS, of the peripheral wall 4c, the second side wall 4a23 facing
25 the extension L. The second side wall 4a23 is formed to surround the impeller 2 in
the axial direction of the rotation shaft RS. The second side wall 4a23 has a platelike shape. The second side wall 4a23 does not have the air inlet 5. In the
centrifugal fan 1C, the feature in which the side wall 4a is expanded in the direction
along the rotation shaft RS is applied only to the first side wall 4a1. The centrifugal
30 fan 1C includes the scroll casing 4 that is a single suction scroll casing.
27
[0067]
[Operation and Effect of Centrifugal Fan 1C]
The first side wall 4a1 of the centrifugal fan 1C according to Embodiment 4 and
the first side wall 4a1 of the centrifugal fan 1 according to Embodiment 1 have the
5 same configuration. Thus, the centrifugal fan 1C according to Embodiment 4
including the scroll casing 4 that is a single suction scroll casing is capable of
achieving an effect similar to that of the centrifugal fan 1 according to Embodiment 1.
[0068]
Embodiment 5
10 [Air-conditioning Apparatus 40]
Fig. 17 is a perspective view schematically illustrating an example of an airconditioning apparatus 40 according to Embodiment 5. Fig. 18 is a schematic
diagram illustrating an example of the internal configuration of the air-conditioning
apparatus 40 according to Embodiment 5. Components having the same
15 configurations as those of the components of the centrifugal fan 1 and other
centrifugal fans in Figs. 1 to 16 have the same reference signs, and the descriptions
thereof are omitted. Fig. 18 does not illustrate a top portion 16a to illustrate the
internal configuration of the air-conditioning apparatus 40. The air-conditioning
apparatus 40 according to Embodiment 5 includes one or more of the centrifugal fan
20 1, the centrifugal fan 1A, the centrifugal fan 1B, and the centrifugal fan 1C, and a heat
exchanger 10, which is provided to face the discharge port 42a of, for example, the
centrifugal fan 1. In addition, the air-conditioning apparatus 40 according to
Embodiment 5 includes a case 16, which is provided above a ceiling of an airconditioned room. In the following description, the term "centrifugal fan 1" denotes
25 one of the centrifugal fan 1, the centrifugal fan 1A, the centrifugal fan 1B, and the
centrifugal fan 1C.
[0069]
As illustrated in Fig. 17, the case 16 includes the top portion 16a, a bottom
portion 16b, and side portions 16c, and has a cuboid shape. The shape of the case
30 16 is not limited to a cuboid shape and may be a different shape such as a cylindrical
28
shape, a rectangular column shape, a circular cone shape, a shape having a plurality
of corners, or a shape having a plurality of curved surfaces. The case 16 includes,
as one of the side portions 16c, a side portion 16c having a case discharge port 17.
As illustrated in Fig. 17, the case discharge port 17 and a case air inlet 18 each have
5 a rectangular shape. Each shape of the case discharge port 17 and the case air
inlet 18 is not limited to a rectangular shape and may be a different shape such as a
circular shape or an oval shape. The case 16 includes, as one of the side portions
16c, a side portion 16c having the case air inlet 18, which is a side opposite to the
side having the case discharge port 17. A filter configured to remove dust in the air
10 may be provided at the case air inlet 18. It is sufficient to form the case air inlet 18 at
a position perpendicular to the axial direction of the rotation shaft RS of the centrifugal
fan 1. Thus, for example, the bottom portion 16b may have the case air inlet 18.
[0070]
The case 16 accommodates two centrifugal fans 1, a motor 6, and the heat
15 exchanger 10. The centrifugal fans 1 each include the scroll casing 4 including the
impeller 2 and the bell mouth 3. The motor 6 is supported by a motor support 9a,
which is fixed to the top portion 16a of the case 16. The motor 6 has an output shaft
6a. The output shaft 6a is provided to extend in parallel with the side having the
case air inlet 18 and the side having the case discharge port 17 of the side portions
20 16c. As illustrated in Fig. 18, in the air-conditioning apparatus 40, the two impellers
2 are attached to the output shaft 6a. The impellers 2 form airflow to be suctioned
into the case 16 from the case air inlet 18 and blown out into an air-conditioned space
from the case discharge port 17. The number of the centrifugal fans 1 to be
provided in the case 16 is not limited to two and may be one or three or more.
25 [0071]
As illustrated in Fig. 18, the centrifugal fans 1 are attached to a partition plate
19. The partition plate 19 partitions the internal space of the case 16 into a space
SP11, which is at the suction sides of the scroll casings 4, and a space SP12, which
is at the discharge sides of the scroll casings 4.
30 [0072]
29
The heat exchanger 10 is provided to face the discharge ports 42a of the
centrifugal fans 1. The heat exchanger 10 is provided in an air passage in the case
16 for air discharged by the centrifugal fans 1. The heat exchanger 10 adjusts the
temperature of air suctioned into the case 16 from the case air inlet 18 and to be
5 blown out into an air-conditioned space from the case discharge port 17. A heat
exchanger having a known structure is applicable to the heat exchanger 10.
[0073]
[Operation Example of Air-conditioning Apparatus 40]
When the impellers 2 are rotated by driving the motor 6, air in an air10 conditioned space is suctioned into the case 16 through the case air inlet 18. The air
suctioned into the case 16 is guided into the bell mouths 3 and suctioned into the
impellers 2. The air suctioned into the impellers 2 is blown out in radial directions of
the impellers 2. The air blown out from the impellers 2 passes through the scroll
casings 4, is blown out from the discharge ports 42a of the scroll casings 4, and is
15 then supplied to the heat exchanger 10. The air supplied to the heat exchanger 10
is subjected to heat exchange during passing through the heat exchanger 10, and the
temperature and humidity of the air are adjusted. The air that has passed through
the heat exchanger 10 is blown out into the air-conditioned space from the case
discharge port 17.
20 [0074]
[Operation and Effect of Air-conditioning Apparatus 40]
The air-conditioning apparatus 40 according to Embodiment 5 includes, for
example, the centrifugal fan 1 according to Embodiment 1 and is thus capable of
achieving an effect similar to that of the centrifugal fan 1 according to Embodiment 1.
25 Accordingly, for example, the air-conditioning apparatus 40 is capable of sending, to
the heat exchanger 10, air whose pressure has been efficiently increased by the
centrifugal fan 1.
[0075]
Embodiment 6
30 [Refrigeration Cycle Apparatus 50]
30
Fig. 19 is a diagram illustrating the configuration of a refrigeration cycle
apparatus 50 according to Embodiment 6. One or more of the centrifugal fan 1, the
centrifugal fan 1A, the centrifugal fan 1B, and the centrifugal fan 1C are usable for an
indoor fan 202 of the refrigeration cycle apparatus 50 according to Embodiment 6.
5 Although a case in which the refrigeration cycle apparatus 50 is used for air
conditioning will be described below, the refrigeration cycle apparatus 50 is not limited
to being used for air conditioning. For example, the refrigeration cycle apparatus 50
is usable for refrigeration or air conditioning in a refrigerator, a freezer, a vending
machine, an air-conditioning apparatus, a refrigeration apparatus, a hot-water supply
10 apparatus, or other apparatuses.
[0076]
The refrigeration cycle apparatus 50 according to Embodiment 6 performs air
conditioning by transferring heat between outdoor air and indoor air via refrigerant to
heat or cool an indoor space. The refrigeration cycle apparatus 50 according to
15 Embodiment 6 includes an outdoor unit 100 and an indoor unit 200. In the
refrigeration cycle apparatus 50, a refrigerant circuit in which refrigerant circulates is
formed by connecting the outdoor unit 100 and the indoor unit 200 by refrigerant
pipes 300 and 400. The refrigerant pipe 300 is a gas pipe in which gas phase
refrigerant flows. The refrigerant pipe 400 is a liquid pipe in which liquid phase
20 refrigerant flows. Two-phase gas-liquid refrigerant may flow in 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 successively connected via refrigerant
pipes.
25 [0077]
(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 and discharges suctioned refrigerant. The flow
30 switching device 102 is, for example, a four-way valve, that is, a device configured to
31
switch between directions in which refrigerant flows. The refrigeration cycle
apparatus 50 is capable of realizing a heating operation or a cooling operation by
switching refrigerant flows with the flow switching device 102 on the basis of
instructions from a controller 110.
5 [0078]
The outdoor heat exchanger 103 exchanges heat between refrigerant and
outdoor air. The outdoor heat exchanger 103 functions as an evaporator in the
heating operation and exchanges heat between low-pressure refrigerant flowing in
through the refrigerant pipe 400 and outdoor air to evaporate and gasify the
10 refrigerant. The outdoor heat exchanger 103 functions as a condenser in the cooling
operation and exchanges heat between outdoor air and refrigerant that has been
compressed by the compressor 101 and that has flowed in from the flow switching
device 102 to condense and liquify the refrigerant. An outdoor fan 104 is provided at
the outdoor heat exchanger 103 to increase the efficiency of heat exchange between
15 refrigerant and outdoor air. An inverter may be attached to the outdoor fan 104, and
the operating frequency of a fan motor may be varied by the inverter to vary the
rotation speed of the fan. The expansion valve 105 is an expansion device (flow
control unit). The expansion valve 105 functions as an expansion valve by adjusting
the amount of refrigerant flowing through the expansion valve 105. The expansion
20 valve 105 adjusts refrigerant pressure by varying the opening degree thereof. For
example, when the expansion valve 105 is formed by an electronic expansion valve,
the opening degree is adjusted on the basis of instructions from the controller 110.
[0079]
(Indoor Unit 200)
25 The indoor unit 200 includes the indoor heat exchanger 201, which is
configured to exchange heat between refrigerant and indoor air, and the indoor fan
202, which is configured to adjust the flow of air to be subjected to heat exchange in
the indoor heat exchanger 201. The indoor heat exchanger 201 functions as a
condenser in the heating operation and exchanges heat between indoor air and
30 refrigerant flowing in through the refrigerant pipe 300 to condense and liquify the
32
refrigerant, and the refrigerant then flows out toward the refrigerant pipe 400. The
indoor heat exchanger 201 functions as an evaporator in the cooling operation and
exchanges heat between indoor air and refrigerant whose pressure is reduced by the
expansion valve 105 to evaporate and gasify the refrigerant that has received heat
5 of the air, and the refrigerant then flows out toward the refrigerant pipe 300. The
indoor fan 202 is provided to face the indoor heat exchanger 201. One or more of
the centrifugal fan 1 according to Embodiment 1 to the centrifugal fan 1 to the
centrifugal fan 1C according to Embodiment 4 are applicable to the indoor fan 202.
The operating speed of the indoor fan 202 is determined by user settings. An
10 inverter may be attached to the indoor fan 202, and the operating frequency of a fan
motor (not illustrated) may be varied by the inverter to vary the rotation speed of the
impeller 2.
[0080]
[Operation Example of Refrigeration Cycle Apparatus 50]
15 Next, the cooling operation will be described as an operation example of the
refrigeration cycle apparatus 50. High-temperature, high-pressure gas refrigerant
compressed and discharged by the compressor 101 flows into the outdoor heat
exchanger 103 via the flow switching device 102. The gas refrigerant that has
flowed into the outdoor heat exchanger 103 is condensed into low-temperature
20 refrigerant by being subjected to heat exchange with outdoor air sent by the outdoor
fan 104, and the low-temperature refrigerant flows out from the outdoor heat
exchanger 103. The refrigerant that has flowed out from the outdoor heat exchanger
103 is expanded and decompressed into low-temperature, low-pressure two-phase
gas-liquid refrigerant by the expansion valve 105. The two-phase gas-liquid
25 refrigerant flows into the indoor heat exchanger 201 of the indoor unit 200 and is
evaporated into low-temperature, low-pressure gas refrigerant by being subjected to
heat exchange with indoor air sent by the indoor fan 202, and the low-temperature,
low-pressure gas refrigerant flows out from the indoor heat exchanger 201. In this
case, the indoor air that has been cooled by removing heat by the refrigerant
30 becomes conditioned air, and the conditioned air is blown out into an air-conditioned
33
space from a discharge port of the indoor unit 200. The gas refrigerant that has
flowed out from the indoor heat exchanger 201 is suctioned into the compressor 101
via the flow switching device 102 and is compressed again. A series of the above
operations is repeated.
5 [0081]
Next, the heating operation will be described as an operation example of the
refrigeration cycle apparatus 50. High-temperature, 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
10 refrigerant that has flowed into the indoor heat exchanger 201 is condensed into lowtemperature refrigerant by being subjected to heat exchange with indoor air sent by
the indoor fan 202, and the low-temperature refrigerant flows out from the indoor heat
exchanger 201. In this case, the indoor air that has been heated by receiving heat
from the gas refrigerant becomes conditioned air, and the conditioned air is blown out
15 into an air-conditioned space from the discharge port of the indoor unit 200. The
refrigerant that has flowed out from the indoor heat exchanger 201 is expanded and
decompressed into low-temperature, low-pressure two-phase gas-liquid refrigerant by
the expansion valve 105. The two-phase gas-liquid refrigerant flows into the outdoor
heat exchanger 103 of the outdoor unit 100 and is evaporated into low-temperature,
20 low-pressure gas refrigerant by being subjected to heat exchange with outdoor air
sent by the outdoor fan 104, and the low-temperature, low-pressure gas refrigerant
flows out from the outdoor heat exchanger 103. The gas refrigerant that has flowed
out from the outdoor heat exchanger 103 is suctioned into the compressor 101 via the
flow switching device 102 and is compressed again. A series of the above
25 operations is repeated.
[0082]
The refrigeration cycle apparatus 50 according to Embodiment 6 includes, for
example, the centrifugal fan 1 according to Embodiment 1 and is thus capable of
achieving an effect similar to that of the centrifugal fan 1 according to Embodiment 1.
30 Accordingly, for example, the refrigeration cycle apparatus 50 is capable of sending,
34
to the indoor heat exchanger 201, air whose pressure has been efficiently increased
by the indoor fan 202.
[0083]
Combinations of Embodiments 1 to 6 described above can be implemented.
5 The configurations in the embodiments above are examples. Thus, the
configurations can be combined with other known techniques, and some of the
configurations can be omitted or modified without departing from the gist.
Reference Signs List
[0084]
10 1: centrifugal fan, 1A: centrifugal fan, 1B: centrifugal fan, 1C: centrifugal fan, 2:
impeller, 2a: back plate, 2a1: peripheral portion, 2b: axial portion, 2c: side plate, 2c1:
first side plate, 2c2: second side plate, 2d: blade, 2e: air inlet, 3: bell mouth, 4: scroll
casing, 4a: side wall, 4a1: first side wall, 4a2: second side wall, 4a21: second side
wall, 4a23: second side wall, 4c: peripheral wall, 4c11: first edge, 4c12: second edge,
15 5: air inlet, 5a: first air inlet, 5b: second air inlet, 6: motor, 6a: output shaft, 9a: motor
support, 10: heat exchanger, 14: bulging portion, 16: case, 16a: top portion, 16b:
bottom portion, 16c: side portion, 17: case discharge port, 18: case air inlet, 19:
partition plate, 30: unit, 31: wall, 40: air-conditioning apparatus, 41: scroll portion, 41b:
outer end portion, 41m: expanded portion, 41m2: second expanded portion, 41p:
20 expansion start portion, 41p2: second expansion start portion, 41s: inner end portion,
42: discharge portion, 42a: discharge port, 42a11: first edge end portion, 42a12:
second edge end portion, 42a21: third edge end portion, 42a22: fourth edge end
portion, 42b: extended plate, 42c: diffuser plate, 42d: first edge, 42e: second edge,
43: tongue portion, 50: refrigeration cycle apparatus, 100: outdoor unit, 101:
25 compressor, 102: flow switching device, 103: outdoor heat exchanger, 104: outdoor
fan, 105: expansion valve, 110: controller, 200: indoor unit, 201: indoor heat
exchanger, 202: indoor fan, 300: refrigerant pipe, 400: refrigerant pipe
35
We Claim :
[Claim 1]
A centrifugal fan comprising:
an impeller having a back plate driven to rotate; and
5 a scroll casing including
a peripheral wall provided in parallel with an axial direction of a rotation
shaft of the back plate to surround the impeller, and having a volute shape along a
rotation direction of the back plate,
a first side wall extending along a first edge of the peripheral wall, the
10 first edge being at one end, in the axial direction of the rotation shaft, of the peripheral
wall, the first side wall facing a virtual extension of the back plate, the virtual
extension of the back plate being perpendicular to the rotation shaft, the first side wall
having a first air inlet defined therein and configured to let air in, and
a discharge port from which airflow generated by the impeller is
15 discharged,
the scroll casing being configured such that
an inner end portion of the volute shape of the scroll casing, an expanded
portion, and a first edge end portion are arranged in a named order in the rotation
direction, the first edge end portion being an end of a first edge, defining the
20 discharge port, of the first side wall, the first edge end portion being farther from the
rotation shaft than an other end of the first edge is to the rotation shaft, and
distance L1distance LM>distance LS is satisfied where
LS is a distance between the first side wall at the inner end portion of the volute
shape and the virtual extension of the back plate,
25 LM is a distance between the first side wall at the expanded portion and the
virtual extension of the back plate, the expanded portion being a portion at which the
distance between the first side wall and the virtual extension of the back plate is
larger than LS, and
L1 is a distance between
30 the first side wall at the first edge end portion, and
36
the virtual extension of the back plate.
[Claim 2]
The centrifugal fan of claim 1, wherein the scroll casing is configured such that
the distance between the first side wall and the virtual extension gradually increases
5 in the rotation direction from the inner end portion toward the expanded portion.
[Claim 3]
The centrifugal fan of claim 2, wherein when an expansion start portion is a
portion at which the distance between the first side wall and the virtual extension
starts to increase in the rotation direction, and an angle at a position of the inner end
10 portion is 0 degrees, the expansion start portion is formed between a position at 0
degrees and a position at 180 degrees in the rotation direction.
[Claim 4]
The centrifugal fan of any one of claims 1 to 3, wherein the scroll casing is
configured such that distance L1distance L2distance LS is satisfied where L2 is a
15 distance between the first side wall at a second edge end portion and the virtual
extension, the second edge end portion being the other end of the first edge, the
second edge end portion being closer to the rotation shaft.
[Claim 5]
The centrifugal fan of any one of claims 1 to 4, wherein the expanded portion is
20 formed between, in the rotation direction, a position at 180 degrees relative to the
inner end portion and a position where a line connecting the rotation shaft and the
first edge end portion forms a first angle.
[Claim 6]
The centrifugal fan of any one of claims 1 to 5, wherein the first side wall has a
25 bulging portion bulging toward a side opposite to the virtual extension.
[Claim 7]
The centrifugal fan of any one of claims 1 to 6, wherein
the scroll casing further includes a second side wall extending along a second
edge of the peripheral wall, the second edge being at an other end, in the axial
30 direction, of the peripheral wall, the second side wall facing the virtual extension, the
37
second side wall having a second air inlet defined therein and configured to let air in,
and
the scroll casing is configured such that
the inner end portion, a second expanded portion, and a third edge end portion
5 are arranged in a named order in the rotation direction, the third edge end portion
being an end of a second edge, defining the discharge port, of the second side wall,
the third edge end portion being farther from the rotation shaft than an other end of
the second edge is to the rotation shaft, and
distance L3distance LM2>distance LS2 is satisfied where
10 LS2 is a distance between the second side wall at the inner end portion and the
virtual extension,
LM2 is a distance between the second side wall at the second expanded
portion and the virtual extension, the second expanded portion being a portion at
which the distance between the second side wall and the virtual extension is larger
15 than LS2, and
L3 is a distance between
the second side wall at the third edge end portion, and
the virtual extension.
[Claim 8]
20 The centrifugal fan of claim 7, wherein the scroll casing is configured such that
the distance between the second side wall and the virtual extension gradually
increases in the rotation direction from the inner end portion toward the second
expanded portion.
[Claim 9]
25 The centrifugal fan of claim 8, wherein when a second expansion start portion
is a portion at which the distance between the second side wall and the virtual
extension starts to increase in the rotation direction, and an angle at the position of
the inner end portion is 0 degrees, the second expansion start portion is formed
between a position at 0 degrees and a position at 180 degrees in the rotation
30 direction.
38
[Claim 10]
The centrifugal fan of any one of claims 7 to 9, wherein the scroll casing is
configured such that distance L3distance L4distance LS2 is satisfied where L4 is a
distance between the second side wall at a fourth edge end portion and the virtual
5 extension, the fourth edge end portion being the other end of the second edge, the
fourth edge end portion being closer to the rotation shaft.
[Claim 11]
The centrifugal fan of any one of claims 7 to 10, wherein the second expanded
portion is formed between, in the rotation direction, a position at 180 degrees relative
10 to the inner end portion and a position where a line connecting the rotation shaft and
the third edge end portion forms a second angle.
[Claim 12]
The centrifugal fan of any one of claims 7 to 11, wherein the second side wall
has a bulging portion bulging toward a side opposite to the virtual extension.
15 [Claim 13]
The centrifugal fan of claim 6 or 12, wherein the bulging portion is formed to
extend in a radial direction of the rotation shaft.
[Claim 14]
The centrifugal fan of claim 13, wherein a plurality of bulging portions, each of
20 which is the bulging portion, are formed at positions in the rotation direction.
[Claim 15]
The centrifugal fan of any one of claims 1 to 6, wherein
the scroll casing further includes a second side wall extending along a second
edge of the peripheral wall, the second edge being at an other end, in the axial
25 direction, of the peripheral wall, the second side wall facing the virtual extension, the
second side wall having a second air inlet defined therein and configured to let air in,
and
a distance between the second side wall and the virtual extension is constant in
the rotation direction.
30 [Claim 16]
39
The centrifugal fan of any one of claims 1 to 6, wherein
the scroll casing further includes a second side wall extending along a second
edge of the peripheral wall, the second edge being at an other end, in the axial
direction, of the peripheral wall, the second side wall facing the virtual extension, and
5 the second side wall is formed to surround the impeller in the axial direction.
[Claim 17]
An air-conditioning apparatus comprising:
the centrifugal fan of any one of claims 1 to 16; and
a heat exchanger provided to face the discharge port of the centrifugal fan.
10 [Claim 18]
A refrigeration cycle apparatus comprising the centrifugal fan of any one of
claims 1 to 16.