JP2020090913A - Centrifugal fan - Google Patents

Abstract

To provide a centrifugal fan which can cool a motor effectively while achieving reduction of manufacturing costs and inhibiting vibration during operation.SOLUTION: A centrifugal fan 1 includes: a casing 9; a motor 3 having a motor wall 31 supported by a motor support wall 93, a boss part 33 formed at a center of the motor wall 31, passing through an opening 97, and protruding into a housing space 90, and a drive shaft 35 protruding from the boss part 33 in the housing space 90; and an impeller 50 disposed within the housing space 90. A first cavity part S1, which is formed by at least a part of the motor support wall 93 being spaced apart from the motor wall 31 in an axial direction of the drive shaft 35 over a range from an outer peripheral edge 31E of the motor wall 31 to the boss part 33, is formed between the motor support wall 93 and the motor wall 31. A second cavity part S2, which is formed by at least a part of an inner peripheral edge 97E of the opening 97 being spaced apart from the boss part 33 in a radial direction of the drive shaft 35, is formed between the opening 97 and the boss part 33.SELECTED DRAWING: Figure 3

Description

The present invention relates to centrifugal fans.

Patent Document 1 discloses an air supply fan device which is an example of a conventional centrifugal fan. This air supply fan device includes a combustion chamber wall, a fan motor, an air supply fan, and a fan motor cooling fan.

The combustion chamber wall partitions a part of the combustion chamber. A ventilation hole is formed through the wall of the combustion chamber. The fan motor is arranged on the opposite side of the combustion chamber wall from the combustion chamber. The fan motor has a motor wall, a boss portion, and a rotating shaft. The motor wall is supported by the combustion chamber wall with a mounting plate interposed. The boss portion is formed at the center of the motor wall. The rotary shaft projects from the boss through the ventilation hole into the combustion chamber. The entire motor wall and boss portion are separated from the combustion chamber wall in the axial direction of the rotating shaft.

The air supply fan is arranged in the combustion chamber. The air supply fan has a main plate and a plurality of blades. The main plate is integrally rotatably fixed to the rotary shaft. The blades are arranged along the outer peripheral edge of the main plate.

In addition to the air supply fan, a fan motor cooling fan is attached to the rotary shaft together with two stoppers and a spring. The fan motor cooling fan is arranged between the boss portion and the combustion chamber wall.

In this air supply fan device, the fan motor operates to rotate the fan motor cooling fan together with the rotating shaft and the air supply fan, so that the air around the fan motor passes between the boss portion and the combustion chamber wall. Further, it passes through the ventilation holes and flows into the combustion chamber. The fan motor is cooled by this air flow.

Japanese Unexamined Patent Publication No. 5-52321

However, in the above-mentioned conventional centrifugal fan, since the fan motor cooling fan and the like are assembled on the rotary shaft, it is difficult to reduce the number of parts and it is difficult to simplify the rotary shaft and its periphery.

Further, in this centrifugal fan, a structure in which a fan motor cooling fan or the like is mounted on the rotating shaft and the rotating shaft protruding from the boss portion of the fan motor into the accommodation space through the ventilation hole Due to the increased length, dynamic unbalance is likely to occur in the rotary shaft, and the rotary shaft and the air supply fan are likely to vibrate due to rotation.

As a result, this centrifugal fan has a problem that it is difficult to effectively cool the motor while realizing reduction in manufacturing cost and suppression of vibration during operation.

The present invention has been made in view of the above conventional circumstances, and provides a centrifugal fan capable of effectively cooling a motor while realizing reduction in manufacturing cost and suppression of vibration during operation. Is a problem to be solved.

The centrifugal fan of the present invention has a cochlear shape that defines a storage space, and a casing having a motor support wall having an opening formed therethrough,
A motor wall that is disposed on the side opposite to the accommodation space with respect to the motor support wall and that is formed in the center of the motor wall that is supported by the motor support wall and that passes through the opening and is inside the accommodation space. A motor having a boss portion that protrudes in the housing, and a drive shaft that protrudes from the boss portion in the accommodation space,
An impeller having a main plate arranged in the accommodation space and fixed to the drive shaft so as to be integrally rotatable, and a plurality of blades arranged along an outer peripheral edge of the main plate,
Between the motor support wall and the motor wall, at least a part of the motor support wall extends in the axial direction of the drive shaft from the motor wall over the range from the outer peripheral edge of the motor wall to the boss portion. A first space is formed which is separated from
A second gap is formed between the opening and the boss, and at least a part of an inner peripheral edge of the opening is separated from the boss in the radial direction of the drive shaft. Characterize.

In the centrifugal fan of the present invention, since the motor cooling fan is not provided on the drive shaft of the motor, the number of parts can be reduced and the drive shaft and its periphery can be simplified.

Further, in this centrifugal fan, the motor cooling fan is not provided on the drive shaft, and the boss portion of the motor passes through the opening of the motor support wall and protrudes into the accommodation space to reduce the protruding length of the drive shaft. With the configuration that can be shortened, dynamic imbalance of the drive shaft is unlikely to occur, and the drive shaft and the impeller are less likely to vibrate due to rotation.

Further, in this centrifugal fan, when the motor operates and the drive shaft and the impeller rotate, in the accommodation space, as compared with the inner region located radially inside the drive shaft with respect to each blade of the impeller, The pressure in the outer region located radially outside the drive shaft is higher than that of each blade of the impeller. Then, the air having the increased pressure is discharged from the accommodation space. Here, according to the results of the earnest research conducted by the inventor, the pressure in the gap area is lowered by the flow of air generated in the gap area between the stationary motor support wall and the main plate of the rotating impeller. Then, the air around the motor flows into the gap area via the first void portion and the second void portion, merges with the air in the outer area in the accommodation space, and is discharged from the accommodation space. .. At this time, the air around the motor comes into contact with the motor wall while flowing through the first gap, and further comes into contact with the boss while flowing through the second gap, whereby the heat of the motor can be effectively taken away.

Therefore, in the centrifugal fan of the present invention, the manufacturing cost can be reduced and the vibration during operation can be suppressed, and the motor can be effectively cooled.

The first gap is preferably formed by narrowing a region surrounding the opening in the motor support wall so as to be separated from the motor wall in the axial direction of the drive shaft.

In this case, since the first void portion can be easily formed by drawing, the manufacturing cost can be further reduced. Further, in this case, the rigidity of the motor support wall can be improved by drawing the motor support wall into a three-dimensional shape.

It is desirable that the motor support wall has a motor support wall main body, a motor mounting plate that is assembled to the motor support wall main body, and has an opening and a mounting portion to which the motor wall is mounted.

In this case, the motor mounting plate, which is separate from the motor support wall body, can be easily manufactured by using a processing method such as press working, punching working, or drawing working, so that the manufacturing cost can be reduced. Further, the motor mounting plate can be easily processed into a shape capable of suitably forming the first void portion and the second void portion.

It is desirable that the impeller has a plurality of auxiliary blades formed by penetrating the main plate and projecting toward the motor support wall.

In this case, the auxiliary blade rotates together with the drive shaft and the impeller, so that the air flow in the gap area can be further promoted. As a result, in this centrifugal fan, the air around the motor can more easily flow into the gap area via the first gap portion and the second gap portion, so that the heat of the motor can be more effectively removed.

According to the centrifugal fan of the present invention, it is possible to effectively cool the motor while realizing reduction of manufacturing cost and suppression of vibration during operation.

FIG. 1 is a schematic diagram of a water heater to which the centrifugal fan of the embodiment is applied. FIG. 2 is a front view of the centrifugal fan of the embodiment. FIG. 3 is a sectional view showing an AA section of FIG. FIG. 4 is an exploded perspective view of the centrifugal fan of the embodiment. FIG. 5 is an enlarged cross-sectional view of a main part of FIG. 3, and is a diagram schematically showing a flow of air passing through the first void portion and the second void portion.

Embodiments embodying the present invention will be described below with reference to the drawings.

(Example)
As shown in FIG. 1, the centrifugal fan 1 of the embodiment is an example of a specific mode of the centrifugal fan of the present invention, and is applied to a water heater 8. After explaining the schematic configuration of the water heater 8, the specific configuration of the centrifugal fan 1 will be described.

<Outline of water heater>
The water heater 8 is a forced air supply/exhaust type water heater. The water heater 8 includes a housing 80, a combustion chamber 82, and a double pipe 89. The combustion chamber 82 is housed inside the housing 80. An air supply space 81 is formed between the inner wall surface of the housing 80 and the combustion chamber 82.

The double pipe 89 has an air supply pipe 87 and an exhaust pipe 88 housed inside the air supply pipe 87. The lower end of the air supply pipe 87 is connected to the upper portion of the housing 80 and communicates with the air supply space 81. The lower end of the exhaust pipe 88 passes through the upper portion of the housing 80 and communicates with the combustion chamber 82. The double pipe 89 extends upward from the housing 80, then bends, passes through the wall W1, and projects to the outside.

Further, the water heater 8 includes the centrifugal fan 1. Although the specific configuration of the centrifugal fan 1 will be described in detail later, the centrifugal fan 1 is connected to the lower portion of the combustion chamber 82. The centrifugal fan 1 includes a casing 9, a motor 3, and an impeller 50.

The casing 9 defines a housing space 90 by a side wall 92, a motor support wall 93, and the like. The side wall 92 is formed with an intake port 9A that connects the air supply space 81 and the accommodation space 90 to each other. At the upper part of the casing 9, a discharge port 9B that communicates with the accommodation space 90 and the combustion chamber 82 is formed.

The motor 3 is arranged on the side opposite to the housing space 90 with respect to the motor support wall 93. The impeller 50 is arranged in the accommodation space 90 and is connected to the drive shaft 35 of the motor 3.

Further, the water heater 8 includes a burner 83 and a heat exchanger 84 which are housed in the combustion chamber 82, respectively. A gas supply pipe (not shown) is connected to the burner 83. The heat exchanger 84 is arranged above the burner 83. To the heat exchanger 84, a water supply pipe (not shown) for supplying water from the outside of the housing 80 and a hot water discharge pipe (not shown) for discharging hot water to the outside of the housing 80 are connected.

<Hot water supply operation of water heater>
In the water heater 8 having such a configuration, when the hot water supply operation is started, the motor 3 of the centrifugal fan 1 operates to rotate the impeller 50. As a result, the outdoor air is sucked into the accommodation space 90 of the centrifugal fan 1 via the air supply pipe 87, the air supply space 81 and the suction port 9A, and is forcibly supplied to the combustion chamber 82 via the discharge port 9B. To be done.

The burner 83 mixes the air supplied to the combustion chamber 82 and the fuel gas supplied from a gas supply pipe (not shown) to ignite them to generate combustion exhaust gas. The heat exchanger 84 causes the water supplied from a water supply pipe (not shown) to exchange heat with the combustion exhaust gas of the burner 83 to heat the water. In this way, the hot water having a desired temperature in the heat exchanger 84 is discharged to the outside of the housing 80 via a hot water outlet pipe (not shown) and supplied to the hot water outlet.

The combustion exhaust gas used for heat exchange in the heat exchanger 84 is discharged outdoors via the exhaust pipe 88. At this time, heat exchange is performed between the air flowing through the air supply pipe 87 and the combustion exhaust gas flowing through the exhaust pipe 88. Therefore, the combustion exhaust gas flowing through the exhaust pipe 88 is cooled to a low temperature and then discharged to the outside, so that the environmental load can be reduced. Further, since the air flowing through the air supply pipe 87 is heated to a high temperature and then introduced into the air supply space 81, the thermal efficiency can be improved.

<Specific configuration of centrifugal fan>
Next, the centrifugal fan 1 will be described in detail with reference to FIGS. In the following description, the shaft center of the drive shaft 35 of the motor 3 is shown in FIGS. 2 to 5 as the drive shaft center X35, and the shape and the like are based on the drive shaft center X35 direction and the radial direction of the drive shaft center X35. Will be explained. The direction of the drive shaft center X35 is an example of the "axial direction of the drive shaft" in the present invention. The radial direction of the drive shaft center X35 is an example of the "radial direction of the drive shaft" in the present invention.

<Casing>
As shown in FIGS. 3 and 4, etc., in the centrifugal fan 1, the casing 9 has a peripheral wall 91, a side wall 92, and a motor support wall 93, which are each made of a steel plate. In the casing 9, the peripheral wall 91 is joined to the outer peripheral edge of the side wall 92 and the outer peripheral edge of the motor supporting wall 93 in a state where the side wall 92 and the motor supporting wall 93 face each other with a predetermined gap in the direction of the drive axis X35. It has a cochlea shape that divides the accommodation space 90 by being processed.

As shown in FIG. 4, the suction port 9A is a round hole penetrating the side wall 92 centering on the drive shaft center X35. The peripheral wall 91 has one end edge 91E and the other end edge 91F extending in the drive axis X35 direction. The discharge port 9B is a rectangular hole formed between the one end edge 91E and the other end edge 91F of the peripheral wall 91.

The motor support wall 93 has a motor support wall body 94 and a motor mounting plate 95. The motor support wall main body 94 includes an outer peripheral edge to which the peripheral wall 91 of the motor support wall 93 is joined, and an impeller insertion hole 94H is provided at the center thereof.

The impeller insertion hole 94H is a large-diameter round hole centered on the drive shaft center X35. The impeller insertion hole 94H is set to a size such that the motor support wall body 94 does not interfere with the impeller 50 when the impeller 50 is arranged in the housing space 90.

The motor mounting plate 95 has a substantially disc shape centered on the drive shaft center X35, and an opening 97 is provided at the center thereof. The opening 97 is a round hole centered on the drive axis X35. The opening portion 97 is set to a size that secures a sufficient gap with the outer peripheral surface of the boss portion 33, which will be described later.

The motor mounting plate 95 has a set screw 95F inserted into a screw hole (not shown) penetrating through the outer peripheral edge thereof at a plurality of positions, and the set screw 95F is screwed into the motor support wall main body 94. As shown, the motor support wall main body 94 is assembled to close the impeller insertion hole 94H.

As shown in FIG. 4, a recess 98 and a mounting portion 96 are formed on the motor mounting plate 95.

The recess 98 is formed into a substantially truncated cone shape so that the region of the motor support wall 93 surrounding the opening 97 in the motor mounting plate 95 approaches the side wall 92 in the direction of the drive axis X35.

The recess 98 includes an inclined portion 98A and a flat portion 98B. The inclined portion 98A is inclined so as to bite into the accommodation space 90 from the outer peripheral edge of the recess 98. The flat portion 98B is connected to the inner peripheral edge of the inclined portion 98A, extends so as to approach the drive axis X35, and reaches the opening 97.

A region of the motor mounting plate 95 located radially outside the drive shaft center X35 with respect to the inclined portion 98A is referred to as an outer region 95D. The flat portion 98B is located closer to the side wall 92 than the outer region 95D and extends parallel to the outer region 95D.

The mounting portion 96 is three bulging portions that are connected to the inner peripheral edge of the outer region 95D, bulge to approach the drive axis X35, and divide the inclined portion 98A of the recess 98 into three arc portions. The attachment portion 96 extends parallel to the outer region 95D. The mounting portion 96 has a screw hole 96F formed therein.

<Motor>
As shown in FIG. 3, the motor 3 has a motor housing 32, a motor wall 31, and a boss portion 33. The motor housing 32 is made of a steel plate and has a substantially bottomed cylindrical shape centered on the drive shaft center X35. A bearing 32T is attached to the bottom of the motor housing 32.

The motor wall 31 and the boss portion 33 are integrally formed by drawing or cutting a steel plate. The motor wall 31 has a substantially disc shape centered on the drive shaft center X35, and a boss portion 33 is formed in the center thereof. The boss portion 33 has a substantially cylindrical shape centered on the drive axis X35. A bearing 33T is assembled in the boss portion 33.

By joining the opening edge of the motor housing 32 and the outer peripheral edge 31E of the motor wall 31, a motor chamber 3A surrounded by the motor housing 32, the motor wall 31, and the boss portion 33 is formed.

The drive shaft 35 is supported by the motor housing 32, the motor wall 31, and the boss portion 33 via bearings 32T and 33T, so that the drive shaft 35 can rotate around the drive shaft center X35.

The stator 3S is fixed to the inner peripheral surface of the motor housing 32. A rotor 3R is integrally rotatably fixed to a portion of the drive shaft 35 located inside the motor chamber 3A. The rotor 3R is arranged in the stator 3S. A control board 3C is fixed to the surface of the motor wall 31 on the side of the motor chamber 3A. The control board 3C includes a control IC, a power transistor, a resistor and the like. The motor 3 rotates the rotor 3R and the drive shaft 35 around the drive axis X35 by supplying electric power to the stator 3S via the control board 3C.

As shown in FIGS. 2 and 4, the motor wall 31 is formed with three small pieces 31F protruding from the outer peripheral edge 31E thereof to the outside in the radial direction of the drive shaft center X35. The set screw 3F is inserted into a screw hole (not shown) formed through the small piece 31F, and the set screw 3F is screwed into the screw hole 96F formed in the mounting portion 96 of the motor mounting plate 95. 96, and is supported by the motor mounting plate 95 of the motor support wall 93. In this way, the motor 3 is arranged on the side opposite to the housing space 90 with respect to the motor support wall 93.

As shown in FIG. 3, with the motor wall 31 supported by the motor mounting plate 95, the boss portion 33 passes through the opening 97 of the motor mounting plate 95 and projects into the accommodation space 90. The drive shaft 35 projects from the boss 33 in the accommodation space 90.

<First Gap and Second Gap>
As shown in FIGS. 3 and 5, a first gap S<b>1 is formed between the motor mounting plate 95 of the motor support wall 93 and the motor wall 31.

In the first space S<b>1, the slope 98</b>A and the flat part 98</b>B of the recess 98 formed in the motor mounting plate 95 extend over the range from the outer peripheral edge 31</b>E of the motor wall 31 to the outer peripheral surface of the boss portion 33. From the drive shaft center X35.

The first space S1 is formed by narrowing a region surrounding the opening 97 in the motor mounting plate 95, that is, the recess 98 so as to be separated from the motor wall 31 in the drive shaft center X35 direction.

A second space S2 is formed between the opening 97 of the motor mounting plate 95 and the boss 33.

The second gap S2 is formed such that the entire circumference of the inner peripheral edge 97E of the opening 97 of the motor mounting plate 95 is separated from the outer peripheral surface of the boss portion 33 in the radial direction of the drive shaft center X35.

<impeller>
As shown in FIGS. 3 and 4, the impeller 50 includes a main plate 51, a facing plate 52, and a plurality of blades 53. In this embodiment, the main plate 51, the facing plate 52, and the plurality of blades 53 are made of steel plate.

The main plate 51 has a substantially disk shape centered on the drive shaft center X35, and a shaft hole 51H is provided at the center thereof.

As shown in FIG. 3, the facing plate 52 has a substantially annular shape centered on the drive shaft center X35, and a large diameter hole 52H is provided at the center thereof. The large-diameter hole 52H has a larger diameter than the suction port 9A of the side wall 92. The facing plate 52 faces the main plate 51 in the drive axis X35 direction.

As shown in FIGS. 3 and 4, the blades 53 are arranged along the outer peripheral edge 51</b>E of the main plate 51. The impeller 50 is configured such that one end side of each blade 53 in the drive axis X35 direction is joined to the main plate 51 and the other end side of each blade 53 in the drive axis X35 direction is joined to the counter plate 52. There is.

A plurality of auxiliary blades 54 are formed on the impeller 50. Each of the auxiliary blades 54 has a portion of each blade 53 penetrating the main plate 51 and protruding toward the opposite side of the counter plate 52. The cross-sectional shape of the auxiliary blade 54 is the same as that of the blade 53 except for the portion of the cross-sectional shape of the blade 53 located inside the drive shaft center X35 in the radial direction.

As shown in FIG. 3, with the impeller 50 arranged in the accommodation space 90, the drive shaft 35 is inserted into the shaft hole 51H of the main plate 51, and the nut 35F has a washer or the like interposed at the tip of the drive shaft 35. The main plate 51 is integrally rotatably fixed to the drive shaft 35 by being screwed in the closed state. In this state, the main plate 51 and the motor mounting plate 95 of the motor support wall 93 face each other, the facing plate 52 and the side wall 92 face each other, and each auxiliary blade 54 projects toward the motor mounting plate 95.

As shown in FIGS. 3 and 4, the main plate 51 is provided with an escape portion 51A. The escape portion 51A is formed into a substantially frustoconical shape so that a region surrounding the shaft hole 51H in the main plate 51 escapes from the boss portion 33 in the drive shaft center X35 direction.

In the centrifugal fan 1 having such a configuration, the impeller 50 rotates in the rotation direction R1 shown in FIG. 4 by operating the motor 3. Each blade 53 is inclined in the rotation direction R1 as it goes outward in the radial direction of the drive axis X35. That is, the impeller 50 is a sirocco fan. Similarly to each of the blades 53, each of the auxiliary blades 54 is also inclined in the rotation direction R1 toward the outside in the radial direction of the drive shaft center X35.

The centrifugal fan 1 sucks air into the housing space 90 from the suction port 9A by the rotation of the impeller 50. Then, the sucked air is subjected to centrifugal force by being rotated together with each blade 53 of the impeller 50, is attracted to the peripheral wall 91 side in the accommodation space 90, is compressed, and is discharged from the discharge port 9B.

<Effect>
In the centrifugal fan 1 of the embodiment, since the motor cooling fan is not provided on the drive shaft 35 of the motor 3, it is possible to reduce the number of parts and simplify the drive shaft 35 and its periphery.

Further, in this centrifugal fan 1, the drive shaft 35 is not provided with a motor cooling fan, and the boss portion 33 of the motor 3 passes through the opening 97 penetrating the motor mounting plate 95 of the motor support wall 93. Since the protruding length of the drive shaft 35 can be shortened by protruding into the accommodation space 90, dynamic imbalance of the drive shaft 35 is unlikely to occur, and the drive shaft 35 and the impeller 50 are less likely to vibrate due to rotation.

Furthermore, the inventor analyzes the flow of air around the motor wall 31, the boss portion 33, the motor support wall 93, the impeller 50, and the like in the centrifugal fan 1, and determines the centrifugal fan 1 under a predetermined operating condition. By performing an experiment for measuring the temperature change of the control board 3C and the bearings 32T, 33T and the like during the time operation, the operational effects of the first void S1 and the second void S2 were confirmed as follows. The flow analysis result described above is schematically illustrated in FIG. 5 by a plurality of arrows.

In the centrifugal fan 1, when the motor 3 operates and the drive shaft 35 and the impeller 50 rotate, the centrifugal fan 1 is positioned inside the accommodation space 90 in the radial direction of the drive axis X35 with respect to each blade 53 of the impeller 50. As compared with the inner region E1, the pressure of the outer region E2 located radially outside the drive shaft center X35 with respect to each blade 53 of the impeller 50 is higher. Then, the air whose pressure has increased in the outer region E2 is discharged from the accommodation space 90 via the discharge port 9B.

Here, the pressure of the gap area E3 becomes low due to the flow of air generated in the gap area E3 between the motor mounting plate 95 of the stationary motor support wall 93 and the main plate 51 of the rotating impeller 50. Then, the air around the motor 3 flows into the gap region E3 via the first gap S1 and the second gap S2, merges with the air in the outer region E2 in the accommodation space 90, and is discharged from the accommodation space 90. Will be done. At this time, the air around the motor 3 comes into contact with the motor wall 31 while flowing through the first space S1, and further comes into contact with the boss 33 while flowing through the second space S2, so that the heat of the motor 3 is effectively transferred. Can be robbed.

Therefore, in the centrifugal fan 1 of the embodiment, the manufacturing cost can be reduced and the vibration during operation can be suppressed, and the motor 3 can be effectively cooled. As a result, abnormal overheating of the control board 3C of the motor 3 and the bearings 32T, 33T, etc. can be suppressed, and the stability and durability of the motor 3 can be improved.

Further, in this centrifugal fan 1, as shown in FIGS. 3 and 4, etc., the first space S1 is a region surrounding the opening 97 in the motor mounting plate 95 of the motor support wall 93, that is, the recess 98 is the motor wall 31. Is formed by being squeezed so as to be separated from the drive shaft center X35 direction. That is, since the first void S1 can be easily formed by drawing, the manufacturing cost can be further reduced. Further, the rigidity of the motor mounting plate 95 can be improved by drawing the motor mounting plate 95 into a three-dimensional shape, so that the motor mounting plate 95 can reliably support the motor wall 31.

Further, in this centrifugal fan 1, the motor support wall 93 has a motor support wall main body 94 and a motor mounting plate 95 which is a separate body from the motor support wall main body 94. Therefore, the motor mounting plate 95 can be easily manufactured by using a working method such as press working, punching working, and drawing working, so that the manufacturing cost can be reduced. Further, the motor mounting plate 95 can be easily processed into a shape capable of suitably forming the first void S1 and the second void S2.

Further, in this centrifugal fan 1, as shown in FIG. 5, the auxiliary vanes 54 rotate together with the drive shaft 35 and the impeller 50, so that the air flow in the gap region E3 can be further promoted. As a result, in this centrifugal fan 1, the air around the motor 3 becomes easier to flow into the gap region E3 via the first gap S1 and the second gap S2, so that the heat of the motor 3 is more effectively removed. be able to.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments, and it goes without saying that the invention can be appropriately modified and applied without departing from the spirit of the invention.

For example, in the embodiment, one recess 98 forms one first void S1, but the present invention is not limited to this configuration. For example, the recess 98 may be changed to a plurality of recesses, and the recesses may form a plurality of first voids. Further, the first gap may be non-uniform around the drive shaft. Further, in the embodiment, in the first space S1, the recess 98 of the motor mounting plate 95 that is a part of the motor support wall 93 extends over the range from the outer peripheral edge 31E of the motor wall 31 to the boss portion 33. It is formed so as to be separated from the drive shaft center X35 direction from 31, but is not limited to this configuration. For example, the first gap portion may be formed such that the entire motor support wall is separated from the motor wall in the axial direction of the drive shaft over the range from the outer peripheral edge of the motor wall to the boss portion.

In the embodiment, the second gap S2 is formed such that the entire circumference of the inner peripheral edge 97E of the opening 97 is separated from the outer peripheral surface of the boss portion 33 in the radial direction of the drive shaft center X35, but is not limited to this configuration. For example, a part of the inner peripheral edge 97E of the opening 97 may be protruded inward in the radial direction of the drive shaft center X35 and brought into contact with the outer peripheral surface of the boss portion 33.

It is also possible to adopt a configuration in which a spacer is interposed between the motor support wall and the motor wall, or a foot is provided on at least one of the motor support wall and the motor wall to form the first gap.

INDUSTRIAL APPLICABILITY The present invention is applicable to, for example, a forced air supply type combustion device, a water heater, a heating heat source device, and the like.

DESCRIPTION OF SYMBOLS 1... Centrifugal fan 90... Storage space 97... Opening 93... Motor support wall 9... Casing 31... Motor wall 33... Boss 35... Drive shaft 3... Motor 51... Main plate 51E... Main plate outer peripheral edge 53... Plural blades 50 ... Impeller 31E... Outer peripheral edge of motor wall S1... First void 97E... Inner peripheral edge of opening S2... Second void 94... Motor support wall main body 96... Mounting portion 95... Motor mounting plate 54... Plural auxiliary blades

Claims (4)

A casing having a motor support wall having a cochlear shape that divides the accommodation space, and an opening is provided through the casing,
A motor wall that is disposed on the side opposite to the accommodation space with respect to the motor support wall and that is formed in the center of the motor wall that is supported by the motor support wall and that passes through the opening and is inside the accommodation space. A motor having a boss portion that protrudes in the housing, and a drive shaft that protrudes from the boss portion in the accommodation space,
An impeller having a main plate arranged in the accommodation space and fixed to the drive shaft so as to be integrally rotatable, and a plurality of blades arranged along an outer peripheral edge of the main plate,
Between the motor support wall and the motor wall, at least a part of the motor support wall extends in the axial direction of the drive shaft from the motor wall over the range from the outer peripheral edge of the motor wall to the boss portion. A first space is formed which is separated from
A second gap is formed between the opening and the boss, and at least a part of an inner peripheral edge of the opening is separated from the boss in the radial direction of the drive shaft. Characteristic centrifugal fan. The centrifugal fan according to claim 1, wherein the first gap portion is formed by being narrowed so that a region of the motor support wall surrounding the opening is separated from the motor wall in an axial direction of the drive shaft. The motor support wall is a motor support wall body,
The centrifugal fan according to claim 1 or 2, further comprising: a motor mounting plate that is assembled to the main body of the motor support wall and that has the opening and a mounting portion to which the motor wall is mounted. The said impeller is formed with some auxiliary|assistant blade|wing which a part of each said blade penetrated the said main plate, and protruded toward the said motor support wall. Centrifugal fan.

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