阅读说明：本技术 离心风扇 (Centrifugal fan ) 是由 玉冈健人 平山正士 于 2019-06-20 设计创作，主要内容包括：本发明提供一种离心风扇,其具有：马达；叶轮,其与马达的旋转部一同旋转；以及壳体,其在内部收纳马达和叶轮。壳体具有：罩部,其在叶轮的上侧与中心轴线垂直地扩展；基座部,其在叶轮的下侧与中心轴线垂直地扩展；侧壁部,其在叶轮的径向外侧将罩部和基座部在轴向上连接起来,并且在周向的一部分与罩部和基座部一同形成送风口；以及吸气口,其在比叶轮的径向外侧的端部靠径向内侧的位置沿轴向贯通罩部和基座部中的至少一方。基座部和罩部中的至少一方具有：至少一个孔部,其在比叶轮的径向外侧的端部靠径向外侧的位置沿轴向贯通；以及密封部,其将孔部密封起来。密封部的比重比基座部和罩部中的具有孔部的一方的比重小。(The invention provides a centrifugal fan, comprising: a motor; an impeller that rotates together with a rotating portion of the motor; and a housing that houses the motor and the impeller therein. The housing has: a cover portion which expands perpendicularly to the central axis on the upper side of the impeller; a base portion extending vertically to the central axis below the impeller; a side wall portion axially connecting the cover portion and the base portion on the outer side of the impeller in the radial direction, and forming an air outlet together with the cover portion and the base portion in a part of the circumferential direction; and an air inlet which penetrates at least one of the cover part and the base part along the axial direction at a position closer to the radial inner side than the radial outer end part of the impeller. At least one of the base section and the cover section has: at least one hole portion axially penetrating the impeller at a position radially outward of a radially outward end of the impeller; and a sealing portion that seals the hole portion. The sealing portion has a specific gravity lower than that of the base portion and the cover portion having the hole portion.)

1. A centrifugal fan, comprising:

a motor having a stationary portion having a stator and a rotating portion that rotates about a central axis extending vertically with respect to the stationary portion;

an impeller having a plurality of blades arranged in a circumferential direction around the central axis, the impeller rotating together with the rotating portion; and

a housing that houses at least a part of the motor and the impeller therein,

the housing has:

a cover portion expanding perpendicularly to the central axis on an upper side of the impeller;

a base portion that extends perpendicularly to the central axis below the impeller and to which the stationary portion of the motor is fixed;

a side wall portion that connects the cover portion and the base portion to each other in an axial direction on a radially outer side of the impeller, and that forms an air blowing port together with the cover portion and the base portion in a part of a circumferential direction; and

an air inlet axially penetrating at least one of the cover portion and the base portion at a position radially inward of a radially outward end of the impeller,

at least one of the base portion and the cover portion includes:

at least one hole that penetrates in the axial direction at a position radially outward of a radially outward end of the impeller; and

a sealing portion that seals the hole portion,

the sealing portion has a specific gravity lower than that of one of the base portion and the cover portion having the hole portion.

2. The centrifugal fan according to claim 1,

the hole part penetrates through the base part along the axial direction,

the sealing portion is disposed on a lower surface of the base portion.

3. The centrifugal fan according to claim 2,

the stationary part further has a circuit board electrically connected to the stator,

at least a portion of the circuit board is disposed between the base portion and the sealing portion.

4. The centrifugal fan according to claim 1,

the hole portion penetrates the cover portion in the axial direction,

the seal portion is disposed on an upper surface of the cover portion.

5. The centrifugal fan according to claim 1,

the seal portion is disposed on a surface of one of the base portion and the cover portion having the hole portion, the surface facing the impeller in the axial direction.

6. The centrifugal fan according to claim 1,

the sealing portion is disposed in the hole portion.

7. The centrifugal fan according to any one of claims 1 to 6,

the number of the hole portions provided in the base portion or the cover portion is one.

8. The centrifugal fan according to any one of claims 1 to 6,

the number of the holes provided in the base portion or the cover portion is plural.

9. The centrifugal fan according to any one of claims 1 to 8,

the hole portion has a circular shape when viewed in the axial direction.

10. The centrifugal fan according to claim 8,

the plurality of holes are arranged in a lattice shape when viewed in the axial direction.

11. The centrifugal fan according to any one of claims 1 to 10,

the base portion and the cover portion are made of metal.

12. The centrifugal fan according to any one of claims 1 to 11,

the sealing portion is made of resin.

13. The centrifugal fan according to claim 6,

the material of the sealing portion is thermosetting resin.

Technical Field

The present invention relates to a centrifugal fan.

Background

Conventionally, a centrifugal fan is mounted in an electronic device such as a notebook personal computer to cool the inside of a casing. The centrifugal fan includes a centrifugal impeller, a motor for rotating the impeller, and a casing for housing the impeller and the motor. When the motor of the centrifugal fan is driven, the impeller rotates, thereby generating an air flow inside the electronic apparatus. This allows heat generated from electronic components such as a CPU mounted in the electronic device to be discharged. For example, japanese patent application laid-open No. 2008-223743 describes a structure of a conventional centrifugal fan.

Patent document 1: japanese laid-open patent publication No. 2008-223743

The fan device disclosed in japanese patent application laid-open No. 2008-223743 has a centrifugal impeller, a casing that houses the centrifugal impeller, and a motor that includes a stator. When the motor is started, the centrifugal impeller rotates at a predetermined speed, and air outside the casing is sucked into the casing through the upper air inlet and the lower air inlet provided in the casing. The air sucked into the casing is accelerated in the centrifugal direction by the rotating centrifugal impeller, and then discharged from an exhaust port provided in a side surface of the casing.

In recent years, with the miniaturization of electronic devices, centrifugal fans mounted on the electronic devices are desired to be thinner and lighter while suppressing a reduction in air blowing performance. Therefore, as a method for thinning while suppressing a reduction in the air blowing performance of the centrifugal fan, for example, the following method is considered: the casing for housing the impeller is formed by punching or pressing a flat metal plate while keeping the size of the impeller constant. For example, compared to the case where the plate is formed by spreading the resin in the mold, the plate of the case can be formed by processing the metal plate, and therefore the plate can be made thinner, and finally the entire case can be made thinner. However, when the metal plate is used in this way, it is difficult to reduce the weight of the centrifugal fan including the casing at the same time.

Disclosure of Invention

The purpose of the present invention is to provide a structure for a centrifugal fan that can reduce the weight of the centrifugal fan while suppressing a reduction in air blowing performance of the centrifugal fan.

An exemplary first invention of the present application is a centrifugal fan having: a motor having a stationary portion having a stator and a rotating portion that rotates about a central axis extending vertically with respect to the stationary portion; an impeller having a plurality of blades arranged in a circumferential direction around the central axis, the impeller rotating together with the rotating portion; and a housing that houses at least a part of the motor and the impeller therein, the housing having: a cover portion expanding perpendicularly to the central axis on an upper side of the impeller; a base portion that extends perpendicularly to the central axis below the impeller and to which the stationary portion of the motor is fixed; a side wall portion that connects the cover portion and the base portion to each other in an axial direction on a radially outer side of the impeller, and that forms an air blowing port together with the cover portion and the base portion in a part of a circumferential direction; and an air inlet axially penetrating at least one of the cover portion and the base portion at a position radially inward of a radially outward end of the impeller, at least one of the base portion and the cover portion including: at least one hole that penetrates in the axial direction at a position radially outward of a radially outward end of the impeller; and a sealing portion that seals the hole portion, the sealing portion having a specific gravity smaller than that of one of the base portion and the cover portion having the hole portion.

According to a first aspect of the present invention, the centrifugal fan includes at least one hole portion that penetrates at least one of the base portion and the cover portion in the axial direction. The hole is sealed by a sealing portion having a lower specific gravity than the base portion or the cover portion having the hole. Thus, the centrifugal fan can be reduced in weight while suppressing a reduction in air blowing performance.

Drawings

Fig. 1 is a longitudinal sectional view of a centrifugal fan according to a first embodiment.

Fig. 2 is a partial perspective view of the centrifugal fan of the first embodiment.

Fig. 3 is a partial longitudinal sectional view of the centrifugal fan of the first embodiment.

Fig. 4 is a longitudinal sectional view of a centrifugal fan according to a modification.

Fig. 5 is a longitudinal sectional view of a centrifugal fan according to a modification.

Fig. 6 is a longitudinal sectional view of a centrifugal fan according to a modification.

Fig. 7 is a partial perspective view of a centrifugal fan according to a modification.

Fig. 8 is a partial perspective view of a centrifugal fan according to a modification.

Description of the reference symbols

1. 1B, 1C, 1D, 1E, 1F: a centrifugal fan; 9: a central axis; 10. 10C: a housing; 11. 11B, 11C, 11D, 11E, 11F: a base part; 12: a cover portion; 13: a sidewall portion; 16. 16B, 16C: a wind tunnel region; 20: a motor; 30: a stationary portion; 31: a holder; 32: a stator; 33: a stationary bearing; 34. 34D: a circuit board; 40: a rotating part; 41: a shaft portion; 42: a rotor portion; 50. 50B, 50C, 50D, 50E, 50F: an impeller; 61: a through hole; 71: a cylindrical portion; 72: a bottom plate portion; 81: a stator core; 82: a coil; 90. 90B, 90C, 90D, 90E, 90F: a hole portion; 91. 91B, 91C, 91D, 91E: a sealing part; 110: a lower air suction port; 120: an upper air suction port; 130: an air supply outlet; 331: a sleeve portion; 332: a thrust section; 333: a lubricating fluid; 411: a shaft main body portion; 412: a shaft flange portion; 421: a rotor holder; 422: a yoke; 423: a magnet; 501: a blade; 811: the back of the iron core; 812: teeth; 821: and (4) conducting wires.

Detailed Description

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In the present application, a direction parallel to the central axis of the centrifugal fan is referred to as an "axial direction", a direction perpendicular to the central axis is referred to as a "radial direction", and a direction along an arc centered on the central axis is referred to as a "circumferential direction". In the present application, the shape and positional relationship of the respective portions will be described with the axial direction as the vertical direction and the cover portion side as the upper side with respect to the base portion. However, the orientation of the centrifugal fan according to the present invention when used is not intended to be limited by the definition of the vertical direction. In the present application, the "parallel direction" also includes a substantially parallel direction. In the present application, the "vertical direction" also includes a substantially vertical direction.

<1 > first embodiment >

<1-1. centrifugal Fan construction >

Fig. 1 is a longitudinal sectional view of a centrifugal fan 1 according to a first embodiment. Fig. 2 is a partial perspective view of a portion of the centrifugal fan 1 other than the cover portion 12. The centrifugal fan 1 is mounted on an electronic device such as a notebook personal computer or a tablet personal computer, and generates an air flow for cooling the inside. However, the centrifugal fan 1 of the present invention may be used for purposes other than cooling to generate an air flow. The centrifugal fan according to the present invention may be used for devices other than electronic devices such as automobiles.

As shown in fig. 1 and 2, the centrifugal fan 1 includes a casing 10, a motor 20, and a centrifugal impeller 50.

The casing 10 is a box body that houses at least a part of the motor 20 and the impeller 50 therein. The housing 10 has a base portion 11, a cover portion 12, and a side wall portion 13.

The base portion 11 and the cover portion 12 of the present embodiment are each formed by, for example, punching or pressing a thin and flat metal plate having a thickness of about 0.5 mm. By using a metal plate, the thin-walled base portion 11 and cover portion 12 can be easily obtained. For example, metals such as stainless steel, aluminum alloy, and galvanized steel sheet are used as the material of the base portion 11 and the cover portion 12. That is, the base portion 11 and the cover portion 12 are made of metal. The base portion 11 extends vertically to the central axis 9 extending vertically below the impeller 50. A stationary portion 30 of a motor 20 described later is fixed to the base portion 11. The cover portion 12 extends vertically to the central axis 9 at a position above the base portion 11 and the impeller 50. That is, the cover portion 12 is arranged substantially parallel to the base portion 11. The upper surface of the base portion 11 and the lower surface of the cover portion 12 face each other.

The base portion 11 of the present embodiment has a lower air inlet 110 for taking air into the casing 10. The lower air inlet 110 penetrates the base portion 11 in the axial direction below the impeller 50 and radially inward of the radially outer end of the impeller 50. Here, the base portion 11 has a through hole 61 for fixing a stationary portion 30 of the motor 20 described later. The through hole 61 is formed coaxially with the center axis 9 and penetrates the base portion 11 in the axial direction. The lower air inlet 110 is provided radially outward of the peripheral edge portion constituting the through hole 61. Further, the lower air inlet 110 is provided at a plurality of locations spaced apart from each other in the circumferential direction around the center axis 9 as viewed in the axial direction.

Cover 12 has an upper air inlet 120 for taking air into casing 10. The upper air inlet 120 axially penetrates the cover portion 12 at a position above the impeller 50 and radially inward of the radially outer end of the impeller 50. The upper air inlet 120 is circular when viewed in the axial direction, and is arranged substantially coaxially with the center axis 9. As described above, in the present embodiment, the air inlet for taking in air into the housing 10 is provided in both the base portion 11 and the cover portion 12. However, the air inlet may be provided in at least one of the base portion 11 and the cover portion 12.

The side wall portion 13 is formed on the base portion 11 by injection molding of resin. The side wall portion 13 extends from the base portion 11 toward the upper side, and is expanded along an end edge portion of the base portion 11, contacting the lower surface of the cover portion 12. The cover portion 12 is fixed to the side wall portion 13 by screwing or bonding. Thereby, the base portion 11 and the cover portion 12 are axially connected to each other by the side wall portion 13 on the radially outer side of the impeller 50. The side wall portion 13 forms an air outlet 130 together with the base portion 11 and the cover portion 12 in a part of the circumferential direction. The base portion 11, the cover portion 12, and the side wall portion 13 constitute an air tunnel region 16 surrounding the impeller 50. The wind tunnel region 16 is a region located above the base portion 11, below the cover portion 12, radially inside the side wall portion 13, and radially outside the impeller 50. The air tunnel region 16 communicates with the space outside the casing 10 in the radial direction via the air blowing port 130.

The motor 20 generates a torque according to the drive current, and rotates the impeller 50. The motor 20 has a stationary portion 30 and a rotating portion 40. The stationary portion 30 is relatively stationary with respect to the housing 10. The rotating portion 40 is supported to be rotatable about the central axis 9 with respect to the stationary portion 30.

The stationary part 30 of the present embodiment includes a holder 31, a stator 32, a stationary bearing 33, and a circuit board 34.

The retainer 31 is formed radially inward of the base portion 11 by injection molding of resin. The holder 31 has a cylindrical portion 71 and a bottom plate portion 72. The bottom plate portion 72 extends annularly in the through hole 61. The cylindrical portion 71 extends in a cylindrical shape upward from the bottom plate portion 72. The cylindrical portion 71 and the bottom plate portion 72 surround the center axis 9 in an annular shape.

The stator 32 is an armature having a stator core 81 and a plurality of coils 82. The stator 32 is located above the base portion 11 and radially outside the cylindrical portion 71. The stator core 81 is formed of a laminated steel plate in which electromagnetic steel plates such as silicon steel plates are laminated in the axial direction, for example. The stator core 81 is fixed to the outer peripheral surface of the cylindrical portion 71 with an adhesive, for example, and is indirectly supported by the base portion 11 via the holder 31. The stator core 81 may be directly supported by the base portion 11.

The stator core 81 has an annular core back 811 and a plurality of teeth 812 protruding radially outward from the core back 811. The plurality of coils 82 are an assembly of wires 821 wound around the plurality of teeth 812. A part of lead wire 821 is drawn out to a position lower than base portion 11 through lower air inlet 110, for example. The plurality of teeth 812 and the plurality of coils 82 are preferably arranged in a ring shape at substantially equal intervals in the circumferential direction around the central axis 9.

The stationary bearing 33 is fixed to the inside of the holder 31 by bonding and is supported thereby. The stationary bearing 33 has a sleeve portion 331 and a thrust portion 332. The sleeve portion 331 extends substantially cylindrically about the central axis 9. The thrust portion 332 extends in a plate shape in the radial direction around the center axis 9, and closes the lower end of the sleeve portion 331. A part of the shaft portion 41 of the rotating portion 40, which will be described later, is accommodated radially inside the sleeve portion 331 and above the thrust portion 332.

A circuit board 34 for supplying a driving current to the motor 20 is disposed on a lower surface of the base portion 11. The wiring 821 is connected to the circuit board 34. Thereby, the circuit board 34 is electrically connected to the stator 32. The driving current of the motor 20 is supplied from an external power supply (not shown) to the coil 82 via the circuit board 34 and the lead 821.

The rotating portion 40 of the present embodiment includes a shaft portion 41 and a rotor portion 42.

The shaft portion 41 is disposed along the center axis 9. The shaft portion 41 has a shaft body portion 411 and a shaft flange portion 412. The shaft main body 411 extends in a columnar shape along the center axis 9. The shaft flange portion 412 extends radially outward from the lower end portion of the shaft body 411.

The outer peripheral surface of the shaft body 411 and the inner peripheral surface of the sleeve 331 radially face each other with a small gap in which a lubricating liquid 333 is present. A plurality of dynamic pressure grooves (not shown) are provided on at least one of the outer peripheral surface of the shaft body 411 and the inner peripheral surface of the sleeve portion 331. Further, the lower surface of the shaft flange portion 412 and the upper surface of the thrust portion 332 face each other in the axial direction with a small gap in which the lubricating liquid 333 is present. A plurality of dynamic pressure grooves (not shown) are provided on at least one of the lower surface of the shaft flange portion 412 and the upper surface of the thrust portion 332. The upper surface of the shaft flange portion 412 and the lower surface of the sleeve portion 331 are axially opposed to each other with a small gap in which the lubricant 333 is present. In the present embodiment, the lubricating liquid 333 is continuously present between the inside of the stationary bearing 33 and the outside of the shaft portion 41. For example, polyol ester oil or diester oil is used as the lubricating liquid 333.

When the motor 20 is driven, a hydrodynamic pressure is induced in the lubricating liquid 333 by these dynamic pressure grooves. Thereby, the rotating portion 40 is stably rotated by being supported by the stationary portion 30. That is, in the present embodiment, the fluid dynamic bearing is configured by the stationary bearing 33 as a member on the stationary portion 30 side, the shaft portion 41 as a member on the rotating portion 40 side, the plurality of dynamic pressure grooves, and the lubricating fluid 333. The rotating portion 40 is rotatably supported by a fluid dynamic bearing. However, instead of the fluid dynamic pressure bearing, another type of bearing such as a sliding bearing may be used.

The rotor portion 42 includes a rotor holder 421, a yoke 422, and a magnet 423.

The rotor holder 421 extends in a substantially cylindrical shape from the upper portion of the shaft portion 41 to the radially outer side and extends axially downward at a position radially outward of the stator 32.

The yoke 422 is an annular member disposed substantially coaxially with the central axis 9. The yoke 422 is fixed to the inner circumferential surface of the rotor holder 421 at the radially outer side of the stator 32 by, for example, an adhesive or caulking. The yoke 422 is made of a ferromagnetic material such as iron. This can suppress leakage of the magnetic flux generated from the magnet 423 to the outside.

The magnet 423 is fixed to the inner circumferential surface of the yoke 422 by an adhesive, for example. The magnet 423 of the present embodiment uses an annular permanent magnet. The magnet 423 is located radially outside the stator 32. The inner circumferential surface of the magnet 423 faces radially outer end surfaces of the plurality of teeth 812 of the stator 32 with a slight gap therebetween. Further, N poles and S poles are alternately magnetized in the circumferential direction on the inner circumferential surface of the magnet 423. However, a plurality of magnets may be used instead of the annular magnet 423. In this case, the plurality of magnets may be arranged on the inner circumferential surface of the yoke 422 such that the magnetic pole surfaces of the N-pole and the S-pole are alternately arranged in the circumferential direction.

The impeller 50 has a plurality of blades 501. The plurality of blades 501 are disposed above the base portion 11 and below the cover portion 12. Each blade 501 extends radially outward from the outer circumferential surface of the rotor holder 421. As shown in fig. 2, the plurality of blades 501 are arranged at equal intervals in the circumferential direction around the central axis 9.

In the present embodiment, the shaft portion 41, the rotor portion 42, and the impeller 50 are an integral member. However, the shaft portion 41, the rotor portion 42, and the impeller 50 may be separate members. For example, the rotor portion and the shaft portion may be separate members, and the upper portion of the shaft portion may be fixed by adhesion or press-fitting to a through hole provided in the center of the rotor portion. The shaft portion 41, the rotor portion 42, and the impeller 50 may be formed of a plurality of members.

When a driving current is supplied to the coil 82 of the stator 32, a magnetic flux is generated in the plurality of teeth 812 of the stator core 81. Then, a circumferential torque is generated by the action of the magnetic flux between the teeth 812 and the magnet 423. As a result, the rotating portion 40 of the motor 20 rotates about the central axis 9. Further, the impeller 50, which is a member integrated with the rotating portion 40, rotates about the central axis 9 together with the rotating portion 40. When the impeller 50 rotates, the gas passes through the upper inlet 120 from a space above the casing 10 and passes through the lower inlet 110 from a space below the casing 10, and is taken into the casing 10. The gas taken into the casing 10 is subjected to the centrifugal force of the impeller 50 and is discharged from the air tunnel region 16 in the casing 10 to the side of the casing 10 through the air outlet 130. This enables the electronic device mounted with the centrifugal fan 1 to be cooled.

<1-2. detailed construction of base part >

Next, a more detailed structure of the base portion 11 will be described. Fig. 3 is a partial longitudinal sectional view of the centrifugal fan 1 according to the first embodiment. Hereinafter, fig. 1 and 2 are referred to as appropriate together with fig. 3.

As shown in fig. 1 to 3, the bed portion 11 is provided with a hole portion 90. The hole 90 penetrates the base portion 11 in the axial direction at a position radially outward of the radially outward end of the impeller 50. Further, the hole portion 90 has a circular shape when viewed in the axial direction. Compared to the case where the hole 90 has a polygonal shape including a plurality of corners, the formation can be made easily. In manufacturing the centrifugal fan 1, the hole 90 is provided by punching, for example, a flat metal plate forming the base portion 11. In the present embodiment, three holes 90 are provided in the base portion 11. However, the number of holes 90 is not limited to three as long as at least one hole is provided in the bed portion 11. That is, the number of the holes 90 provided in the base portion 11 may be one or more. In the present embodiment, the strength of the bed portion 11 is ensured to be equal to or higher than a certain level by providing a plurality of holes 90 at intervals rather than one large hole.

The base portion 11 has a sealing portion 91. Specifically, sealing portions 91 that seal the three holes 90 are disposed on the lower surface of the base portion 11. The seal portion 91 is made of a paper or resin sheet having a thickness of about 0.1mm, and coated with an adhesive or a bonding agent on one surface. When manufacturing the centrifugal fan 1, the sealing portion 91 is attached to the lower surface of the base portion 11 to seal the hole portion 90. By using the sheet-shaped sealing portion 91 made of resin, the base portion 11 can be easily sealed. In the present embodiment, each hole 90 is sealed by a seal 91 having a slightly larger area than each hole 90 when viewed in the axial direction. This can reduce the amount of the seal 91 used, and thus can reduce the cost. The sealing portion 91 may be disposed on the entire lower surface of the base portion 11 by one sealing portion. This can reduce the amount of work as compared with the case where the plurality of sealing portions 91 are attached to the lower surface of the base portion 11.

The sealing portion 91 has a specific gravity smaller than that of the base portion 11. The material weight of the sealing portion 91 is lighter than the material weight of the base portion 11 that is originally present in the space formed by the hole portion 90 of the base portion 11. In this way, by providing the hole 90 in the base portion 11 having a large material weight and sealing the hole 90 with the sealing portion 91 having a small material weight instead, the centrifugal fan 1 including the base portion 11 can be made lightweight. At the same time, the entry and exit of gas into and out of the air tunnel region 16 in the housing 10 through the hole 90 can be suppressed. As a result, the centrifugal fan 1 can be reduced in weight while suppressing a reduction in air blowing performance.

<2. modification >

Although the exemplary embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

In the above embodiment, the hole 90 penetrates the base portion 11 in the axial direction, and the sealing portion 91 is disposed on the lower surface of the base portion 11. However, the hole 90 may axially penetrate the cover portion 12 at a position radially outward of the radially outward end of the impeller 50. Specifically, the cover 12 may have a hole 90. Sealing portion 91 having a specific gravity smaller than that of cover portion 12 may be disposed on the upper surface of cover portion 12 to seal hole 90. Specifically, the cover 12 may have a seal 91. This can similarly suppress a reduction in air blowing performance and reduce the weight of the centrifugal fan 1.

Fig. 4 is a longitudinal sectional view of a centrifugal fan 1B according to a modification. In the example of fig. 4, the hole 90B penetrates the bed portion 11B in the axial direction at a position radially outward of the radially outward end of the impeller 50B. Further, a sealing portion 91B having a lower specific gravity than the base portion 11B is disposed on the upper surface of the base portion 11B to seal the hole portion 90B. As a result, the centrifugal fan 1B can be reduced in weight while suppressing a reduction in air blowing performance as in the above-described embodiment. In addition, the thickness of the sealing portion 91B is much thinner than that of the base portion 11B. In the present modification, the sealing portion 91B is disposed on the upper surface of the base portion 11B facing the air tunnel region 16B, so that the upper surface of the base portion 11B in the vicinity of the hole portion 90B can be in a state of substantially no step. Therefore, the influence on the airflow of the wind tunnel region 16B can be suppressed.

The hole portion may axially penetrate the cover portion at a position radially outward of a radially outward end of the impeller, and the seal portion may be disposed on a lower surface of the cover portion. This makes it possible to bring the lower surface of the cover portion in the vicinity of the hole portion into a state with almost no step, and thus to suppress the influence on the air flow in the air channel region.

Fig. 5 is a longitudinal sectional view of a centrifugal fan 1C according to another modification. In the example of fig. 5, the hole 90C penetrates the bed portion 11C in the axial direction at a position radially outward of the radially outward end of the impeller 50C. On the other hand, unlike the above-described embodiment and modification, in the example of fig. 5, a sealing portion 91C having a specific gravity smaller than that of the base portion 11C is disposed in the hole portion 90C. The sealing portion 91C is made of thermosetting resin. In manufacturing the centrifugal fan 1C, the liquid sealing portion 91C is disposed in the hole 90C and then cured, thereby sealing the hole 90C. This can reduce the weight of the centrifugal fan 1C including the base portion 11C. At the same time, the entry and exit of the gas into and out of the air tunnel region 16C in the housing 10C through the hole 90C can be suppressed. As a result, the centrifugal fan 1C can be reduced in weight while suppressing a reduction in air blowing performance. Further, the upper surface of the base portion 11C in the vicinity of the hole portion 90C can be brought into a state in which there is almost no step. Therefore, the influence on the airflow of the wind tunnel region 16C can be suppressed.

Fig. 6 is a longitudinal sectional view of a centrifugal fan 1D according to another modification. In the example of fig. 6, the hole 90D penetrates the bed portion 11D in the axial direction at a position radially outward of the radially outward end of the impeller 50D. On the other hand, the sealing portion 91D is attached to the entire lower surface of the base portion 11D, and seals the hole portion 90D from below. At least a part of the circuit board 34D disposed on the lower surface of the base portion 11D is disposed between the base portion 11D and the sealing portion 91D in the axial direction. This can further prevent the circuit board 34D from falling off the base portion 11D.

Fig. 7 is a partial perspective view of a portion other than the cover portion of a centrifugal fan 1E according to another modification. In the example of fig. 7, one hole 90E is provided in the base portion 11E at a position radially outward of the radially outward end of the impeller 50E. The hole 90E penetrates the base portion 11E in the axial direction, and has an area larger than the total area of the plurality of holes described in the above-described embodiment and modification example when viewed in the axial direction. The hole 90E is sealed by the sealing portion 91E. In this way, when one hole 90E is provided, the work amount of punching work for the base portion 11E can be reduced, and the volume of the base portion 11E can be further reduced to reduce the weight of the centrifugal fan 1E.

Fig. 8 is a partial perspective view of a portion other than the cover portion of a centrifugal fan 1F according to another modification. In the example of fig. 8, the plurality of holes 90F are arranged in a lattice shape when viewed in the axial direction, at positions radially outward of the radially outward end of the impeller 50F in the base portion 11F. In the present modification, each hole 90F penetrates the base portion 11F in the axial direction, and each hole 90F has a hexagonal shape when viewed in the axial direction. However, the shape of each hole 90F is not limited thereto. As in the present modification, by providing the plurality of holes 90F in a grid pattern with a gap therebetween, the strength of the base portion 11F can be maintained at a constant level or more, and the weight of the centrifugal fan 1F can be reduced.

That is, in the centrifugal fan according to the present invention, a hole portion that penetrates at least one of the base portion and the cover portion in the axial direction is provided on the radially outer side of the radially outer end portion of the impeller. The sealing portion having a lower specific gravity than one of the base portion and the cover portion having the hole is disposed to seal the hole. This makes it possible to reduce the weight of the centrifugal fan while suppressing a reduction in air blowing performance. The number of holes provided in at least one of the base portion and the cover portion may be one or more. The seal portion may be disposed on one of the base portion and the cover portion having the hole portion, on a surface facing the impeller in the axial direction, or may be disposed on a surface opposite to the surface facing the impeller in the axial direction. The sealing portion may be disposed in the hole portion.

The detailed shape of the centrifugal fan may be different from the shape shown in the drawings of the present application.

In addition, the respective elements appearing in the above-described embodiment and the modified examples may be appropriately combined within a range in which no contradiction occurs.

Industrial applicability

The present invention can be used for a centrifugal fan.