FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
MULTI-BLADE CENTRIFUGAL AIR-SENDING DEVICE;
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
5 Technical Field
[0001]
The present disclosure relates to a multi-blade centrifugal air-sending device
including a scroll casing.
Background Art
10 [0002]
A multi-blade centrifugal air-sending device includes a fan and a scroll casing
having a spiral shape and housing the fan. The fan is constituted by a back plate
having a disk shape, a rim having an annular shape, and a plurality of blades provided
between the back plate and the rim, and is configured to suck air from the side of the
15 rim by rotating and cause the air to flow out to an air passage in the inside of the scroll
casing via a space between the blades. The airflow is pressurized in the air passage
in the inside of the scroll casing and blown out through an outlet. As a means for
increasing the air volume in a multi-blade centrifugal air-sending device, there is a
method of increasing the number of blades. When the number of blades is increased
20 to increase the air volume, however, noise is increased due to the increase in the
number of blades. Thus, there is a device (refer to, for example, Patent Literature 1) in
which a forward blade (sirocco blade) is provided on the outer peripheral side of each
blade and a rearward blade (turbo blade) is provided on the inner peripheral side of the
blade to thereby increase the air volume without increasing the number of blades. In
25 the multi-blade centrifugal air-sending device in Patent Literature 1, the side of a back
plate of each blade is extended on the inner peripheral side with respect to the inner
side position of a rim in the radial direction to be configured such that air is induced to
the side of the back plate of the blade.
Citation List
30 Patent Literature
3
[0003]
Patent Literature 1: Japanese Unexamined Patent Application Publication No.
2000-240590
Summary of Invention
5 Technical Problem
[0004]
It is, however, impossible on the side of the rim between the blades to obtain the
effect of pressurization by the turbo blade, since the turbo blade is not included in an
end portion on the side of the rim while the sirocco blade and the turbo blade are
10 included in an end portion on the side of the back plate in each blade of the multi-blade
centrifugal air-sending device disclosed in Patent Literature 1.
The present disclosure has been made to solve the aforementioned problem, and
an object of the present disclosure is to provide a multi-blade centrifugal air-sending
device capable of pressurizing air on the side of a rim between blades of a fan.
15 Solution to Problem
[0005]
A multi-blade centrifugal air-sending device according to the present disclosure
includes a fan including a back plate having a disk shape, a plurality of blades arranged
at a peripheral portion of the back plate in a circumferential direction, and a rim having
20 an annular shape and coupling the plurality of blades to each other, the plurality of
blades being connected at respective first end portions on one side to the back plate,
the rim being provided at respective second end portions of the plurality of blades on a
side opposite to the one side where the respective first end portions are present; and a
scroll casing having a spiral shape and including a facing side wall where an air inlet is
25 provided and a peripheral wall, the scroll casing housing the fan such that the side wall
faces the respective second end portions of the plurality of blades, the scroll casing
being configured such that air is introduced through the air inlet and blown out to the
outer peripheral side. Each of the blades includes a sirocco blade portion constituted
by a forward blade, and a turbo blade portion constituted by a rearward blade and
30 provided on the inner peripheral side with respect to the sirocco blade portion. The
4
respective second end portions of the blades each extend along the side wall and
include an end surface of the sirocco blade portion and an end surface of the turbo
blade portion. Each of the blades extends from inner peripheral ends of the side wall
toward the inner peripheral side such that a portion of the end surface of the turbo blade
5 portion is positioned on the inner peripheral side with respect to the inner peripheral
ends of the side wall while a remaining portion of the end surface of the turbo blade
portion is covered by the side wall.
Advantageous Effects of Invention
[0006]
10 According to the present disclosure, the respective second end portions of the
blades extending along the side wall each include the end surface of the sirocco blade
portion and the end surface of the turbo blade portion, and each of the blades extends
toward the inner side from the side wall such that a portion of the end surface of the
turbo blade portion is exposed from the inner peripheral ends of the side wall while a
15 remaining portion thereof is covered by the side wall. Therefore, a flow passage
covered by the side wall and in which gaps between the blades are expanded toward
the outer peripheral side by the turbo blade portion is formed on the side of the rim of
the fan, and it is thus possible to provide a multi-blade centrifugal air-sending device
capable of pressurizing air on the side of the rim of the fan.
20 Brief Description of Drawings
[0007]
[Fig. 1] Fig. 1 is a schematic external view of a configuration of a multi-blade
centrifugal air-sending device according to Embodiment 1 as viewed in a direction
parallel to a rotational axis.
25 [Fig. 2] Fig. 2 is a sectional view in which a section of the multi-blade centrifugal
air-sending device in Fig. 1 along line A-A is schematically illustrated.
[Fig. 3] Fig. 3 is a schematic view of a configuration of a fan of the multi-blade
centrifugal air-sending device in Fig. 1 as viewed in a direction parallel to the rotational
axis.
5
[Fig. 4] Fig. 4 is a sectional view in which a section of the fan in Fig. 3 along line
B-B is schematically illustrated.
[Fig. 5] Fig. 5 is a partial perspective view in which a portion of an outer
peripheral portion of the fan in Fig. 3 is enlarged.
5 [Fig. 6] Fig. 6 is a view of a configuration of the portion of the outer peripheral
portion of the fan illustrated in Fig. 5 as viewed in a direction parallel to the rotational
axis.
[Fig. 7] Fig. 6 is a schematic view of a configuration of a turbo blade portion of a
blade of a multi-blade centrifugal air-sending device according to Embodiment 2 as
10 viewed in a direction parallel to the rotational axis.
[Fig. 8] Fig. 8 is a schematic view of a configuration of a turbo blade portion of a
blade of a multi-blade centrifugal air-sending device according to Embodiment 3 as
viewed in a direction parallel to the rotational axis.
Description of Embodiments
15 [0008]
Hereinafter, a multi-blade centrifugal air-sending device 100 according to an
embodiment will be described with reference to the drawings. In the following
drawings including Fig. 1, relative dimensional relationships, shapes, and others of
constituent members may differ from actual ones. Members having identical signs in
20 the following drawings are identical or correspond to each other, which is common to
the entire content of the description. For ease of understanding, terms indicating
directions (for example, "upper", "lower", "forward", "rearward", and the other similar
terms) are used, as appropriate. These terms are, however, merely thus used for
convenience of description and are not intended to limit the arrangements and
25 orientations of a device or components.
[0009]
Embodiment 1
Fig. 1 is a schematic external view of a configuration of the multi-blade centrifugal
air-sending device 100 according to Embodiment 1 as viewed in a direction parallel to a
30 rotational axis RS. Fig. 2 is a sectional view in which a section of the multi-blade
6
centrifugal air-sending device 100 in Fig. 1 along line A-A is schematically illustrated.
With reference to Fig. 1 and Fig. 2, a basic structure of the multi-blade centrifugal airsending device 100 will be described.
[0010]
5 As illustrated in Fig. 1, the multi-blade centrifugal air-sending device 100 is an airsending device of a multi-blade centrifugal type and includes a fan 10 that generates an
airflow, and a scroll casing 20 that houses the fan 10. The fan 10 includes a back plate
11 having a disk shape, a rim 13 (Fig. 2) having an annular shape and facing the back
plate 11, and a plurality of blades 12 arranged at a peripheral portion of the back plate
10 11 in the circumferential direction of the back plate 11. The back plate 11 is provided
with a shaft portion 11b to which a motor (not illustrated) is connected.
[0011]
The scroll casing 20 includes a scroll portion 21 and a discharge portion 22
having a discharge port 22b for air, and rectifies the airflow blown out from the fan 10 in
15 a centrifugal direction. The scroll casing 20 has a spiral shape, and an air passage
20a expanding gradually toward the discharge port 22b is formed in the inside of the
scroll casing 20.
[0012]
The scroll portion 21 forms the air passage 20a that converts a dynamic pressure
20 of the airflow generated by the rotation of the fan 10 into a static pressure. The scroll
portion 21 includes a side wall 23 covering the fan 10 in the axial direction of the
rotational axis RS of the fan 10 and each having an air inlet 23b through which air is
sucked; and a peripheral wall 24 surrounding the fan 10 from the outer side in the radial
direction of the rotational axis RS. The scroll portion 21 also includes a tongue portion
25 25 positioned between the discharge portion 22 and a winding start portion 24a of the
peripheral wall 24 and constituting a curved surface. The tongue portion 25 is
configured to guide the airflow blown out from the fan 10 in the centrifugal direction in
the vicinity of the winding start portion 24a, to be in a rotational direction R of the fan 10
to move toward the discharge port 22b via the scroll portion 21.
30 [0013]
7
The radial direction of the rotational axis RS is a direction perpendicular to the
axial direction of the rotational axis RS. An internal space of the scroll portion 21
constituted by the peripheral wall 24 and the side wall 23 serves as the above-described
air passage 20a. In the air passage 20a, the airflow blown out from the fan 10 flows
5 along the peripheral wall 24.
[0014]
In the example illustrated in Fig. 2, the multi-blade centrifugal air-sending device
100 is a double-suction-type centrifugal air-sending device configured to suck air from
both end sides in the axial direction of the imaginary rotational axis RS of the fan 10.
10 The side wall 23 is disposed on both sides of the fan 10 in the axial direction of the
rotational axis RS of the fan 10. Each side wall 23 of the scroll casing 20 has the air
inlet 23b to enable air to circulate between the fan 10 and the outside of the scroll
casing 20. As illustrated in Fig. 1, the air inlet 23b has a circular shape, and the fan 10
is disposed in the scroll casing 20 such that the center of the air inlet 23b and the center
15 of the shaft portion 11b of the fan 10 substantially coincide with each other.
[0015]
As illustrated in Fig. 2, the scroll casing 20 is a casing of a double suction type
having, on both sides of the back plate 11 in the axial direction of the rotational axis RS
of the fan 10, the side wall 23 having the air inlet 23b. The two side walls 23 are
20 provided to face each other with the peripheral wall 24 interposed therebetween in the
scroll casing 20.
[0016]
As illustrated in Fig. 1, the air inlet 23b provided at each side wall 23 is formed by
a bell mouth 26. That is, the bell mouth 26 forms the air inlet 23b in communication
25 with a space formed by the back plate 11 and the plurality of blades 12 in the fan 10.
In the following description, the space formed by the back plate 11 and the plurality of
blades 12 may be referred to as a flow passage 11a of the fan 10.
[0017]
As illustrated in Fig. 2, the bell mouth 26 rectifies the air sucked through the air
30 inlet 23b of each side wall 23 and causes the air to flow into a central portion of the fan
8
10 through a fan air inlet 10a. The bell mouth 26 is provided to project from the side
wall 23 toward the inside. More specifically, the bell mouth 26 is formed such that the
opening diameter thereof decreases gradually from the side wall 23 of the scroll casing
20 toward the inside. With such a configuration, when the fan 10 rotates, the air in the
5 vicinity of the air inlet 23b of each side wall 23 flows smoothly along the bell mouth 26
and flows into the fan 10 efficiently through the fan air inlet 10a.
[0018]
As illustrated in Fig. 1, the peripheral wall 24 is constituted by a wall surface
curved in the rotational direction R of the fan 10. The peripheral wall 24 is present, as
10 illustrated in Fig. 2, between the two side walls 23 facing each other in the scroll casing
20 and is provided, as illustrated in Fig. 1, to connect portions of the outer peripheral
edges of the two side walls 23 to each other. The peripheral wall 24 has a curved
inner peripheral surface 24c and guides the airflow blown out to the air passage 20a in
the scroll portion 21 from the fan 10, so as to flow along the inner peripheral surface 24c
15 to the discharge port 22b.
[0019]
The peripheral wall 24 has a configuration in which the wall surface curved as
illustrated in Fig. 1 extends parallel to the axial direction of the rotational axis RS of the
fan 10 as illustrated in Fig. 2. The peripheral wall 24 may have a form inclined with
20 respect to the axial direction of the rotational axis RS of the fan 10, and is not limited to
having the form disposed parallel to the axial direction of the rotational axis RS.
[0020]
As illustrated in Fig. 1, the peripheral wall 24 covers the fan 10 from the outer
side in the radial direction of the shaft portion 11b of the fan 10, and the inner peripheral
25 surface 24c of the peripheral wall 24 faces end portions of the plurality of laterdescribed blades 12 on the outer peripheral side. That is, the inner peripheral surface
24c of the peripheral wall 24 faces the air blowing-out side of the blades 12 of the fan
10. The peripheral wall 24 is provided to extend in the rotational direction R of the fan
10 from the winding start portion 24a positioned at the boundary between the peripheral
30 wall 24 and the tongue portion 25 to a winding end portion 24b positioned at the
9
boundary between the discharge portion 22 and the scroll portion 21 on the side away
from the tongue portion 25. The winding start portion 24a is, of the peripheral wall 24
constituted by the curved wall surface, an end portion on the upstream side of the
airflow generated by the rotation of the fan 10, and the winding end portion 24b is an
5 end portion of the peripheral wall 24 on the downstream side of the airflow generated by
the rotation of the fan 10. More specifically, the peripheral wall 24 has a spiral shape.
The spiral shape is, for example, a logarithmic spiral, an Archimedes' spiral, or a spiral
shape based on an involute curve or any other curve. With such a configuration, the
airflow blown out from the fan 10 into the air passage 20a of the scroll casing 20 flows in
10 the gap between the fan 10 and the peripheral wall 24 smoothly to the direction of the
discharge portion 22. Therefore, the static pressure of air increases in the rotational
direction R of the fan 10 from the tongue portion 25 toward the discharge portion 22 in
the scroll casing 20.
[0021]
15 The discharge portion 22 forms the discharge port 22b through which the airflow
that has been generated by the rotation of the fan 10 and passed through the air
passage 20a of the scroll portion 21 is discharged. The discharge portion 22 is
constituted by a hollow pipe whose section orthogonal to the flow direction of
discharged air has a rectangular shape. The discharge portion 22 is constituted by, for
20 example, plate-shaped four side surfaces. Specifically, the discharge portion 22
includes an extended plate 221 smoothly connected to the winding end portion 24b of
the peripheral wall 24, and a diffuser plate 222 extending from the tongue portion 25 to
face the extended plate 221. The discharge portion 22 also includes a first side wall
portion and a second side wall portion (not illustrated) each extended from a
25 corresponding one of the two side walls 23 to connect both ends of the extended plate
221 and the diffuser plate 222 in the axial direction of the rotational axis RS to each
other. The sectional shape of the discharge portion 22 is not limited to a rectangular
shape. The discharge portion 22 forms a discharge-side air passage 22a that guides
the airflow discharged from the fan 10 and flowing through the gap between the
30 peripheral wall 24 and the fan 10, to be discharged to the outside of the scroll casing 20.
10
[0022]
The tongue portion 25 is formed between the diffuser plate 222 of the discharge
portion 22 and the winding start portion 24a of the peripheral wall 24 in the scroll casing
20. The tongue portion 25 is formed to have a predetermined radius of curvature, and
5 the peripheral wall 24 is smoothly connected to the diffuser plate 222 with the tongue
portion 25 interposed therebetween. The tongue portion 25 suppresses the inflow of
air from the winding end portion to the winding start portion of the spiral air passage 20a
formed in the inside of the scroll casing 20. In other words, the tongue portion 25 has
a role of separating the airflow flowing from an upstream portion of the air passage 20a
10 in the rotational direction R of the fan 10 and the airflow flowing from a downstream
portion of the air passage 20a toward the discharge port 22b in a discharge direction
from each other. The static pressure of the airflow flowing into the discharge-side air
passage 22a of the discharge portion 22 increases while the airflow passes through the
scroll casing 20, to be higher than in the scroll casing 20. The tongue portion 25 is
15 thus configured to have a function of partitioning such different pressures.
[0023]
Fig. 3 is a schematic view of a configuration of the fan 10 of the multi-blade
centrifugal air-sending device 100 in Fig. 1 as viewed in a direction parallel to the
rotational axis RS. Fig. 4 is a sectional view in which a section of the fan 10 in Fig. 3
20 along line B-B is schematically illustrated. As illustrated in Fig. 3, the fan 10 is a
centrifugal fan. The fan 10 is constituted by, for example, a resin material, and, for
example, the back plate 11, the plurality of blades 12, and the rim 13 can be integrally
molded by injection molding. The fan 10 is configured to be driven to rotate by, for
example, a motor (not illustrated) and to forcibly send air in the centrifugal direction, that
25 is, radially outward by a centrifugal force generated by rotating and suck air through the
fan air inlet 10a (refer to Fig. 4) provided on the side of the rim 13. The fan 10 is
rotated by, for example, a motor in the rotational direction R.
[0024]
As illustrated in Fig. 4, the back plate 11 may be formed such that the wall
30 thickness thereof increases toward the center in the radial direction with the rotational
11
axis RS as the center, or may be formed to have a thickness that is constant in the
radial direction with the rotational axis RS as the center. The back plate 11 may have a
shape other than a disk shape as long as the back plate 11 has a plate shape and may
have, for example, a polygonal shape or any other shape. A motor (not illustrated) is
5 connected to the shaft portion 11b provided at a center portion of the back plate 11, and
the back plate 11 is driven to rotate by the motor via the shaft portion 11b.
[0025]
As illustrated in Fig. 3, the plurality of blades 12 are disposed in the
circumferential direction of a plate surface 111 of the back plate 11 with the rotational
10 axis RS as the center such that a predetermined interval is formed between mutually
adjacent blades 12. The plurality of blades 12 disposed at the back plate 11 form the
cylindrical shape of the fan 10. A gap G formed between mutually adjacent blades 12
constitutes the flow passage 11a of the fan 10.
[0026]
15 Each of the plurality of radially provided blades 12 includes a sirocco blade
portion 30 constituted by a forward blade, and a turbo blade portion 40 constituted by a
rearward blade. The turbo blade portion 40 is connected to the sirocco blade portion
30 in the radial direction, and each blade 12 has a shape curved in the radial direction.
The turbo blade portion 40 is provided on the inner peripheral side with respect to the
20 sirocco blade portion 30 to be continuous with the sirocco blade portion 30. The
sirocco blade portion 30 and the turbo blade portion 40 are smoothly connected to each
other at a blade boundary 12b between the sirocco blade portion 30 and the turbo blade
portion 40.
[0027]
25 As illustrated in Fig. 3 and Fig. 4, in the rotation of the back plate 11 about the
rotational axis RS, an end surface of each blade 12 on the inner peripheral side is a
blade leading edge 12f, and an end surface of each blade 12 on the outer peripheral
side is a blade trailing edge 12r. In the example illustrated in Fig. 3, the turbo blade
portion 40 is linearly formed from the blade boundary 12b to the blade leading edge 12f.
30 As illustrated in Fig. 4, the blade leading edge 12f is inclined with respect to the axial
12
direction of the rotational axis RS such that the blade leading edge 12f gradually
approaches the rotational axis RS from the side of the rim 13 toward the side of the
back plate 11 in the axial direction of the rotational axis RS. The blade trailing edge
12r and the blade boundary 12b are each substantially parallel to the rotational axis RS.
5 The detailed configuration of each of the blades 12 will be described later.
[0028]
As illustrated in Fig. 4, each of the plurality of blades 12 is provided between the
back plate 11 and the rim 13 in the axial direction of the rotational axis RS. In the axial
direction of the rotational axis RS, one end of each of the blades 12 is connected to the
10 back plate 11, and the other end of each of the blades 12 extends to the position of the
rim 13.
[0029]
In the following description, the one end of each blade 12 connected to the back
plate 11 and the other end of the blade 12 on the side of the rim 13 in the axial direction
15 of the rotational axis RS may be referred to as an end portion 12d on the side of the
back plate 11 and an end portion 12u on the side of the rim 13, respectively. In
addition, in the following description, a portion of the blade leading edge 12f of each of
the blades 12 connected to the end portion 12d on the side of the back plate 11 is
referred to as a main-plate-side inner peripheral end 12fd, and a portion of the blade
20 leading edge 12f of each of the blades 12 connected to the end portion 12u on the side
of the rim 13 is referred to as a side-plate-side inner peripheral end 12fu.
[0030]
In Fig. 3, a first imaginary circle C1 passing through the main-plate-side inner
peripheral ends 12fd of the blade leading edges 12f of the plurality of blades 12 is
25 indicated by a dash-dotted line, and a third imaginary circle C3 passing through the
blade boundaries 12b of the plurality of blades 12 is indicated by a dashed line. In
addition, a second imaginary circle C2 formed by projecting the inner peripheral ends,
that is, the air inlets 23b of the side wall 23 of the scroll casing 20 illustrated in Fig. 1 in
the axial direction is indicated by a dashed double-dotted line in Fig. 3. The first
13
imaginary circle C1, the second imaginary circle C2, and the third imaginary circle C3
are each a circle centered at the imaginary rotational axis RS of the back plate 11.
[0031]
In a state in which the fan 10 is housed in the scroll casing 20 as illustrated in Fig.
5 2, the end portion 12u of each blade 12 on the side of the rim 13 extends along the side
wall 23 to be substantially parallel to the side wall 23, and a portion of each blade 12
extends toward the inner side further than the inner peripheral ends of the side wall 23.
In the example illustrated in Fig. 2, the end portion 12u of each blade 12 on the side of
the rim 13 and the end portion 12d thereof on the side of the back plate 11 are
10 substantially parallel to each other and extend linearly in a direction perpendicular to the
axial direction of the rotational axis RS.
[0032]
The rim 13 maintains the positional relationship of the tips of the blades 12 and
reinforces the plurality of blades 12. The fan air inlet 10a for causing a gas to flow into
15 the flow passage 11a of the fan 10 is provided on the side of the rim 13 in the fan 10.
[0033]
In the example illustrated in Fig. 4, the rim 13 is provided on the side of the blade
trailing edges 12r at the end portions 12u of the plurality of blades 12. In addition, in
the example illustrated in Fig. 4, the rim 13 and the plurality of blades 12 are provided
20 on both sides of the back plate 11 in the axial direction of the rotational axis RS. The
rim 13 provided on the side of the plate surface 111 of the back plate 11 on one side
couples the plurality of blades 12 disposed on the side of the plate surface 111 of the
back plate 11 on the one side to each other. The rim 13 provided on the side of the
plate surface 112 of the back plate 11 on the other side couples the plurality of blades
25 12 disposed on the side of the plate surface 112 of the back plate 11 on the other side
to each other.
[0034]
As illustrated in Fig. 2, the fan 10 is housed in the scroll casing 20 such that the
side wall 23 of the scroll casing 20 faces the end portions 12u of the plurality of blades
30 12 of the fan 10. Specifically, the fan 10 is set in the scroll casing 20 such that the
14
center of the fan air inlet 10a provided on the side of the rim 13 in the fan 10 and the
center of the air inlet 23b provided at each side wall 23 of the scroll casing 20 coincide
with each other. The fan 10 is supported about an axis by the scroll casing 20 to be
rotatable.
5 [0035]
Since a portion of each blade 12 extends on the inner peripheral side further than
the inner peripheral ends of the side wall 23 as described above, the air sucked through
the fan air inlet 10a is easily taken into the flow passage 11a of the fan 10 due to the
extended blade portion. Since the blade leading edge 12f is inclined as described with
10 reference to Fig. 4, it is possible to reduce resistance on the side of the rim 13 at the
blade portion extending further on the inner peripheral side than the inner peripheral
ends of the side wall 23, and possible to suppress, for example, obstruction of air
suction into the back plate 11 and an increase of noise.
[0036]
15 Since the turbo blade portion 40 is provided on the inner peripheral side with
respect to the sirocco blade portion 30 as illustrated in Fig. 3, the gap G between
mutually adjacent blades 12 is inclined from the side of the blade leading edge 12f
toward the blade boundary 12b in a direction opposite to the rotational direction R.
Therefore, the air caused by the rotation of the fan 10 to flow into a central portion
20 through the fan air inlet 10a can be highly efficiently taken into and sent to the flow
passage 11a of the fan 10. It is thus possible to obtain an effect of increasing the air
volume.
[0037]
Fig. 5 is a partial perspective view in which a portion of an outer peripheral
25 portion of the fan 10 in Fig. 3 is enlarged. In Fig. 5, a portion of the fan 10 on the side
of the plate surface 111 of the back plate 11 on one side is illustrated. Hereinafter, with
the side of the rim 13 and the side of the back plate 11 in the axial direction of the
rotational axis RS being defined as the upper side and the lower side, respectively, a
detailed configuration of the blades 12 will be described with reference to Fig. 3 and Fig.
30 5.
15
[0038]
As illustrated in Fig. 5, in the blades 12, the blade boundaries 12b indicated by
the third imaginary circle C3 are positioned on the outer peripheral side with respect to
the side-plate-side inner peripheral ends 12fu of the blade leading edges 12f. The end
5 portion 12u of each blade 12 on the upper side includes an upper end portion
constituting the upper surface of the sirocco blade portion 30 and an upper end portion
constituting the upper surface of the turbo blade portion 40. The end portion 12d of
each blade 12 on the lower side includes a lower end portion constituting the lower
surface of the sirocco blade portion 30 and a lower end portion constituting the lower
10 surface of the turbo blade portion 40. The turbo blade portion 40 includes a first turbo
blade portion 41 connected to the sirocco blade portion 30, and a second turbo blade
portion 42 on the inner peripheral side with respect to the first turbo blade portion 41.
The first turbo blade portion 41 includes the entirety of the upper end portion of the
turbo blade portion 40 and has a quadrangular shape when the blade 12 is viewed from
15 the rear side in the rotational direction R. The second turbo blade portion 42 includes
the entirety of the blade leading edge 12f of the blade 12 and has a triangular shape
when the blade 12 is viewed from the rear side in the rotational direction R.
[0039]
In a state in which the fan 10 is housed in the scroll casing 20 as illustrated in Fig.
20 1, the blade boundaries 12b of the blades 12 indicated by the third imaginary circle C3
in Fig. 5 are positioned on the outer peripheral side with respect to the inner peripheral
ends of the side wall 23 indicated by the second imaginary circle C2.
[0040]
In the example illustrated in Fig. 5, the side-plate-side inner peripheral ends 12fu
25 of the blade leading edges 12f are positioned at the inner peripheral ends of the side
wall 23 (refer to Fig. 1) indicated by the second imaginary circle C2 in the radial
direction. That is, in the example illustrated in Fig. 5, the entirety of the upper surface
of the first turbo blade portion 41 is covered by the side wall 23, and the entirety of the
second turbo blade portion 42 is exposed on the inner side from the side wall 23. In
30 the radial direction, the positions of the side-plate-side inner peripheral ends 12fu of the
16
blade leading edges 12f do not need to coincide with the positions of the inner
peripheral ends of the side wall 23. As long as at least a portion of the turbo blade
portion 40 is positioned on the inner peripheral side with respect to the inner peripheral
ends of the side wall 23 in the radial direction, air can be taken into the flow passage
5 11a of the fan 10 by an extended portion of each blade 12. Preferably, in order to
increase the suction air volume also on the side of the rim 13 of the blades 12, the sideplate-side inner peripheral ends 12fu of the blade leading edges 12f are positioned on
the inner peripheral side with respect to the inner peripheral ends of the side wall 23
(Fig. 1) indicated by the second imaginary circle C2 in the radial direction.
10 [0041]
Fig. 6 is a view of a configuration of a portion of the outer peripheral portion of the
fan 10 illustrated in Fig. 5 as viewed in a direction parallel to the rotational axis RS. As
illustrated in Fig. 6, in each blade 12 set on the back plate 11, the main-plate-side inner
peripheral end 12fd and the side-plate-side inner peripheral end 12fu of the blade
15 leading edge 12f are substantially parallel to each other.
[0042]
In the example illustrated in Fig. 6, each of the blades 12 has a wall thickness
that is substantially uniform in the radial direction. As illustrated in Fig. 6, a wall
thickness W2 of each blade 12 at the end portion 12u on the side of the rim 13 is thinner
20 than a wall thickness W1 of the blade 12 at the end portion 12d (Fig. 5) on the side of
the back plate 11, and the wall thickness of the blade 12 is configured to become
thinner gradually from the end portion 12d toward the end portion 12u. Therefore, the
gap G formed between mutually adjacent blades 12 expands gradually from the blade
leading edge 12f toward the blade trailing edge 12r in the radial direction and expands
25 gradually from the side of the back plate 11 toward the side of the rim 13 in the axial
direction.
[0043]
With reference to Fig. 1 to Fig. 6, operation of the multi-blade centrifugal airsending device 100 will be described. As illustrated in Fig. 1, when the fan 10 is driven
30 to rotate about the rotational axis RS by a motor (not illustrated), air outside the multi-
17
blade centrifugal air-sending device 100 flows into a central portion of the fan 10 in the
axial direction through the air inlets 23b of the scroll casing 20 and the fan air inlet 10a.
The air that has flowed into the central portion of the fan 10 is taken into the flow
passage 11a of the fan 10 from the blade leading edges 12f due to the rotation of the
5 fan 10 and flows radially outward in the flow passage 11a.
[0044]
As described with reference to Fig. 5 and Fig. 6, the gap G formed between
mutually adjacent blades 12 expands gradually from the blade leading edge12f toward
the blade trailing edge 12r and expands gradually from the side of the back plate 11
10 toward the side of the rim 13. Therefore, it is possible to increase the suction air
volume on the side of the rim 13 at the second turbo blade portion 42, send the air that
has been taken into the flow passage 11a from the side of the back plate 11 at the blade
leading edge 12f, to the side of the rim 13, that is, to the upper side, and increase the air
volume on the side of the rim 13 even in a configuration in which the blade leading edge
15 12f is inclined. The airflow that flows toward the blade boundary 12b on the upper side
of the flow passage 11a in which the air volume is increased is highly efficiently
pressurized by the first turbo blade portion 41 extending from the back plate 11 to the
rim 13 and covered by the side wall 23 (Fig. 1).
[0045]
20 The pressurized airflow that has flowed along the first turbo blade portion 41 in
the flow passage 11a reaches the blade boundary 12b and then flows toward the blade
trailing edge 12r while changing the traveling direction thereof along the sirocco blade
portion 30. Thereafter, the airflow that has reached the blade trailing edge 12r is sent
from the flow passage 11a of the fan 10 to the air passage 20a of the scroll casing 20.
25 The airflow that has been sent from the fan 10 to the air passage 20a is further
pressurized when passing through the spiral air passage 20a expanding toward the
discharge port 22b, and is blown out to the outer peripheral side through the discharge
port 22b.
[0046]
18
In Embodiment 1, the multi-blade centrifugal air-sending device 100 that is a
double-suction-type centrifugal air-sending device has been described. The multiblade centrifugal air-sending device 100, however, may be a single-suction-type
centrifugal air-sending device. The number of the blades 12 is not limited to that in the
5 drawings.
[0047]
As described above, in Embodiment 1, the multi-blade centrifugal air-sending
device 100 includes the fan 10 and the scroll casing 20 having a spiral shape. The fan
10 includes the back plate 11 having a disk shape, the plurality of blades 12 arranged in
10 the circumferential direction at the peripheral portion of the back plate 11, and the rim 13
having an annular shape and coupling the plurality of blades 12 to each other.
Respective first end portions (end portions 12d) of the plurality of blades 12 on one side
are connected to the back plate 11, and the rim 13 is provided at respective second end
portions (end portions 12u) of the plurality of blades 12 on a side opposite to the one
15 side where the respective first end portions are present. The scroll casing 20 includes
the facing side wall 23 where the air inlet 23b is provided and the peripheral wall 24.
The scroll casing 20 houses the fan 10 such that the side wall 23 face the second end
portions (end portions 12u) of the plurality of blades 12, and is configured such that air
is introduced through the air inlets 23b and blown out to the outer peripheral side.
20 Each blade 12 includes the sirocco blade portion 30 constituted by the forward blade,
and the turbo blade portion 40 constituted by the rearward blade and provided on the
inner peripheral side with respect to the sirocco blade portion 30. The second end
portion (end portion 12u) of each blade 12 extends along the side wall 23 and includes
an end surface of the sirocco blade portion 30 and an end surface of the turbo blade
25 portion 40. Each blade 12 extends from the inner peripheral ends of the side wall 23
toward the inner peripheral side such that a portion of the end surface of the turbo blade
portion 40 is positioned on the inner peripheral side with respect to the inner peripheral
ends of the side wall 23 while a remaining portion of the end surface of the turbo blade
portion 40 is covered by the side wall 23.
30 [0048]
19
Consequently, the flow passage 11a covered by the side wall 23 and in which the
gap G between the blades 12 is widened gradually toward the outer peripheral side by
the turbo blade portion 40 is formed on the side of the rim 13 in the axial direction of the
fan 10. It is thus possible to provide the multi-blade centrifugal air-sending device 100
5 capable of pressurizing air on the side of the rim 13 in the flow passage 11a of the fan
10.
[0049]
The wall thicknesses W1 and W2 of each blade 12 are configured to decrease
gradually from the first end portion (end portion 12d) on the side of the back plate 11
10 toward the second end portion (end portion 12u) on the side of the rim 13.
Consequently, the gap G formed between the mutually adjacent blades 12 expands
gradually from the end portion 12d on the side of the back plate 11 toward the end
portion 12u on the side of the rim 13 in the axial direction, and it is thus possible to
increase the suction air volume on the side of the rim 13.
15 [0050]
The turbo blade portion 40 of each blade 12 is formed to extend linearly from
the side of the sirocco blade portion 30 toward the inner peripheral side.
Consequently, it is possible to simplify the shape of each blade 12 and possible to
facilitate manufacture of the fan 10 and reduce costs thereof, compared with a
20 configuration in which the turbo blade portion 40 is curved in each blade 12.
[0051]
Embodiment 2
Fig. 7 is a schematic view of a configuration of the turbo blade portion 40 of
each blade 12 of the multi-blade centrifugal air-sending device 100 according to
25 Embodiment 2 as viewed in a direction parallel to the rotational axis RS. In
Embodiment 2, the positional relationship between the main-plate-side inner
peripheral end 12fd and the side-plate-side inner peripheral end 12fu of the blade
leading edge 12f differs from that in Embodiment 1.
[0052]
20
In Fig. 7, the arrow F21 indicates the direction of an airflow that passes the
vicinity of the main-plate-side inner peripheral end 12fd of the blade leading edge 12f
during rotation of the fan 10, and the arrow F22 indicates the direction of an airflow
that passes the vicinity of the side-plate-side inner peripheral end 12fu of the blade
5 leading edge 12f during rotation of the fan 10. While the fan 10 rotates, as illustrated
in Fig. 7, an airflow in which the percentage of a circumferential-direction component
increases toward the outer peripheral side of the blade leading edge 12f is generated
in the vicinity of the blade leading edge 12f. In other words, at the blade leading
edge 12f, the percentage of the circumferential-direction component in the airflow that
10 passes the side-plate-side inner peripheral end 12fu is larger than the percentage of
the circumferential-direction component in the airflow that passes the main-plate-side
inner peripheral end 12fd.
[0053]
Thus, in Embodiment 2, the blade leading edge 12f is configured such that an
15 angle 2 formed by the side-plate-side inner peripheral end 12fu of the blade leading
edge 12f and a pressure surface 121 is larger than an angle 1 formed by the mainplate-side inner peripheral end 12fd of the blade leading edge 12f and the pressure
surface 121. A corner where the blade leading edge 12f and the pressure surface
121 meet each other may be chamfered into an arc shape. In Embodiment 2, the
20 angle 1 and the angle 2 satisfy the following relationship.
[0054]
[Math. 1]
0 < 1 < 2 < 90  (Formula 1)
[0055]
25 As described above, in Embodiment 2, the blade leading edge 12f of each blade
12 is formed such that the angle 2 formed by the side-plate-side inner peripheral end
12fu of the blade leading edge 12f and the pressure surface 121 is larger than the
angle 1 formed by the main-plate-side inner peripheral end 12fd of the blade leading
edge 12f and the pressure surface 121.
30 [0056]
21
Consequently, it is possible to suppress generation of a separation vortex W at
a suction surface 122 on the side of the side-plate-side inner peripheral end 12fu of
the blade leading edge 12f, and possible to suppress a decrease of the air volume due
to separation of the airflow from the suction surface 122 and suppress an increase of
5 noise due to generation of the separation vortex W.
[0057]
Embodiment 3
Fig. 8 is a schematic view of a configuration of the turbo blade portion 40 of
each blade 12 of the multi-blade centrifugal air-sending device 100 according to
10 Embodiment 3 as viewed in a direction parallel to the rotational axis RS. As with
Embodiment 2, the configuration in Embodiment 3 also satisfies the relationship in
Formula 1. In Embodiment 3, the shape of the turbo blade portion 40 in the radial
direction differs from those in Embodiment 1 and Embodiment 2. In Fig. 8, the arrow
F31 indicates the direction of an airflow that passes the vicinity of the main-plate-side
15 inner peripheral end 12fd of the blade leading edge 12f during rotation of the fan 10.
[0058]
As illustrated in Fig. 8, the turbo blade portion 40 is constituted by a linear portion
extending linearly from the blade boundary 12b (Fig. 3) with respect to the sirocco blade
portion 30 toward the inner peripheral side, and an inner peripheral end portion 42b
20 curved and connected to the linear portion in the radial direction. The inner peripheral
end portion 42b of the turbo blade portion 40 includes at least a portion of the blade
portion extending toward the inner side further than the inner peripheral end of the side
wall 23 in Fig. 1. In the example illustrated in Fig. 8, the linear portion of the turbo
blade portion 40 is constituted by the first turbo blade portion 41 and a portion 42a of
25 the second turbo blade portion 42 on the side of the first turbo blade portion 41. The
inner peripheral end portion 42b of the turbo blade portion 40 is constituted by a
remaining portion of the second turbo blade portion 42 excluding the portion 42a.
[0059]
22
The inner peripheral end portion 42b of the turbo blade portion 40 is curved with
respect to the linear portion in a direction opposite to the rotational direction R of the fan
10, and has a shape protruding in the rotational direction R of the fan 10.
[0060]
5 Generally, the direction of the airflow flowing into the fan 10 of the multi-blade
centrifugal air-sending device 100 varies depending on an environment (including
atmospheric pressure conditions, and other conditions) in which the multi-blade
centrifugal air-sending device 100 is used and on the capacity range to which the
multi-blade centrifugal air-sending device 100 belongs. For example, under a high10 pressure environment, the airflow does not easily flows in the radial direction
compared with under a low-pressure environment, and the percentage of the
circumferential-direction component in the airflow increases compared with under a
low-pressure environment. Meanwhile, under a low-pressure environment, the
airflow easily flows in the radial direction compared with under a high-pressure
15 environment, and the percentage of a radial-direction component in the airflow
increases compared with under a high-pressure environment.
[0061]
Thus, in Embodiment 3, the inner peripheral end portion 42b of the turbo blade
portion 40 has a curved shape to thereby configure such that an inclination of the
20 blade leading edge 12f in accordance with a usage environment can be easily formed
while maintaining the relationship in Formula 1 by adjusting the degree of the curve.
[0062]
As described above, in the multi-blade centrifugal air-sending device 100
according to Embodiment 3, the turbo blade portion 40 of each blade 12 is constituted
25 by the linear portion extending linearly from the side of the sirocco blade portion 30
toward the inner peripheral side, and the inner peripheral end portion 42b curved and
connected to the linear portion in the radial direction.
[0063]
Consequently, it becomes easy to provide the multi-blade centrifugal air-sending
30 device 100 in which the inclination of the main-plate-side inner peripheral end 12fd
23
varies while the relationship in Formula 1 is satisfied. Therefore, it is possible to
provide the multi-blade centrifugal air-sending device 100 capable of, in response to
an airflow whose direction changes at the main-plate-side inner peripheral end 12fd of
the blade leading edge 12f depending on an environment in which the multi-blade
5 centrifugal air-sending device 100 is used, pressurizing the airflow highly efficiently
while suppressing separation of the airflow from the suction surface 122.
[0064]
Note that the embodiments can be combined together, and modifications and
omissions can be performed, as appropriate, in each embodiment. For example, the
10 rim 13 of the fan 10 may be configured to extend from the blade trailing edges 12r to
the positions of the inner peripheral ends of the side wall 23 indicated by the second
imaginary circle C2 to cover the entirety of the end portion 12u of each blade 12.
Reference Signs List
[0065]
15 10: fan, 10a: fan air inlet, 11: back plate, 11a: flow passage, 11b: shaft portion, 12:
blade, 12b: blade boundary, 12d, 12u: end portion, 12f: blade leading edge, 12fd: mainplate-side inner peripheral end, 12fu: side-plate-side inner peripheral end, 12r: blade
trailing edge, 13: rim, 20: scroll casing, 20a: air passage, 21: scroll portion, 22:
discharge portion, 22a: discharge-side air passage, 22b: discharge port, 23: side wall,
20 23b: air inlet, 24: peripheral wall, 24a: winding start portion, 24b: winding end portion,
24c: inner peripheral surface, 25: tongue portion, 26: bell mouth, 30: sirocco blade
portion, 40: turbo blade portion, 41: first turbo blade portion, 42: second turbo blade
portion, 42a: portion, 42b: inner peripheral end portion, 100: multi-blade centrifugal airsending device, 111, 112: plate surface, 121: pressure surface, 122: suction surface,
25 221: extended plate, 222: diffuser plate, C1: first imaginary circle, C2: second imaginary
circle, C3: third imaginary circle, G: gap, R: rotational direction, RS: rotational axis, W:
separation vortex, W1: wall thickness, W2: wall thickness, 1, 2: angle
24
We Claim :
[Claim 1]
A multi-blade centrifugal air-sending device comprising:
a fan including a back plate having a disk shape, a plurality of blades arranged at
5 a peripheral portion of the back plate in a circumferential direction, and a rim having an
annular shape and coupling the plurality of blades to each other, the plurality of blades
being connected at respective first end portions on one side to the back plate, the rim
being provided at respective second end portions of the plurality of blades on a side
opposite to the one side where the respective first end portions are present; and
10 a scroll casing having a spiral shape and including a facing side wall where an air
inlet is provided and a peripheral wall, the scroll casing housing the fan such that the
side wall faces the respective second end portions of the plurality of blades, the scroll
casing being configured such that air is introduced through the air inlet and blown out to
an outer peripheral side,
15 wherein each of the blades includes a sirocco blade portion constituted by a
forward blade, and a turbo blade portion constituted by a rearward blade and provided
on an inner peripheral side with respect to the sirocco blade portion,
wherein the respective second end portions of the blades each extend along the
side wall and include an end surface of the sirocco blade portion and an end surface of
20 the turbo blade portion, and
wherein each of the blades extends from inner peripheral ends of the side wall
toward the inner peripheral side such that a portion of the end surface of the turbo blade
portion is positioned on the inner peripheral side with respect to the inner peripheral
ends of the side wall while a remaining portion of the end surface of the turbo blade
25 portion is covered by the side wall.
[Claim 2]
The multi-blade centrifugal air-sending device of claim 1,
wherein a wall thickness of each of the blades decreases gradually from the
respective first end portions on a side of the back plate toward the respective second
30 end portions on a side of the rim.
25
[Claim 3]
The multi-blade centrifugal air-sending device of claim 1 or claim 2,
wherein a blade leading edge of each of the blades is formed such that an angle
2 formed by a side-plate-side inner peripheral end of the blade leading edge and a
5 pressure surface is larger than an angle 1 formed by a main-plate-side inner peripheral
end of the blade leading edge and the pressure surface.
[Claim 4]
The multi-blade centrifugal air-sending device of any one of claims 1 to 3,
wherein the turbo blade portion of each of the blades is formed to extend linearly
10 from a side of the sirocco blade portion toward the inner peripheral side.
[Claim 5]
The multi-blade centrifugal air-sending device of claim 3,
wherein the turbo blade portion of each of the blades is constituted by
a linear portion extending linearly from a side of the sirocco blade portion toward
15 the inner peripheral side, and
a curved inner peripheral end portion connected to the linear portion in a radial
direction.