BLOWER

Abstract

A blower improving heat dissipation of a bearing and achieving long operating life without increasing the number of parts is provided. A bearing holding portion rotatably supporting a motor shaft, to which a rotor of a motor and an impeller are assembled on two longitudinal sides, respectively via a bearing, is assembled to a fan casing, and part of the bearing holding portion adjacent to the impeller extends to a position facing an air path and forms part of the air path.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2023-028001, filed on Feb. 27, 2023, and the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a blower used in, for example, a medical instrument, an industrial apparatus, or a consumer appliance.

BACKGROUND ART

A blower has an integral assembly of a resin fan casing, which accommodates an impeller and which is provided with an air path where compressed air flows, and a metal or resin motor casing, which accommodates a motor that drives the impeller to rotate. Driving the motor to rotate the impeller allows the outside air to be suctioned into the fan casing from an axial direction and the compressed air to be delivered from radially outward.

For example, in a blower 50 illustrated in FIG. 3, a rotor 53 is assembled to a motor shaft 52 disposed in a motor casing 51, and an impeller 55 is assembled to the motor shaft 52 extending into a fan casing 54. For the more manageable balance of a rotating element, a cylindrical bearing housing 56 is provided between the rotor 53 assembled to the motor shaft 52 and the impeller 55, and a pair of bearings 57 are assembled into the bearing housing 56. The motor shaft 52 is rotatably supported by the pair of bearings 57, and a metal material (stainless steel) is used for the bearing housing 56.

When the outside air axially suctioned into the fan casing 54 by the rotation of the impeller 55 leaks into the motor casing 51 via a gap present, for example, around the motor shaft 52, a desired static pressure cannot be obtained. Therefore, to improve airtightness, the motor casing 51 and the fan casing 54 are hermetically sealed with a seal member 58 such as an O-ring (refer to JP-A-2021-131021).

SUMMARY OF INVENTION

Technical Problem

The blower is required to have performances such as high pressure, high flow rate, and high response, while downsizing and weight reduction are needed. The trend, therefore, is moving toward downsizing the impeller of the blower to enable higher rotation.

When the impeller rotates at high speed to meet the demand of the high pressure and the high flow rate, the heat generated from the bearings increases, resulting in reduced life. Furthermore, a resin material is often used for the fan casing to meet the demand of the downsizing and the weight reduction. In this case, the resin material reduces the heat dissipation of the blower, compared with the metal material. This further increases the heat generated from the bearings and reduces the life.

To suppress the vibration of the motor casing, the bearing housing is assembled to the resin fan casing via an anti-vibration member (e.g., rubber). This anti-vibration member and the fan casing are low in heat dissipation and structured to suppress airflows around the bearings. Bearing temperature, therefore, tends to rise, causing the reduced life.

If the resin fan casing is changed to a metal fan casing, the heat dissipation of the bearings improves. However, as the blower's weight increases, the heat generated from the motor propagates to the air path via the fan casing, and the temperature of the delivered air increases more than needed.

Solution to Problem

The present invention has been accomplished under the circumstances. An object of the present invention is to provide a blower capable of improving the heat dissipation of bearings disposed between an impeller and a motor and achieving an extended lifespan without increasing the number of parts.

To attain the object, the present invention is configured as follows.

A blower includes an integral assembly of a fan casing accommodating an impeller and a motor casing accommodating a motor that drives the impeller to rotate, and suctions air from an axially central portion of the fan casing and delivering the air from an air path provided radially outward, a bearing rotatably supporting a motor shaft to which a rotor of the motor and the impeller being assembled on two longitudinal sides, respectively, and a metal bearing holding portion holding the bearing being disposed between the impeller and the motor, and the bearing holding portion extending radially outward to a position facing the air path and forming part of the air path.

According to the configurations, part of the metal bearing holding portion disposed between the impeller and the motor extends to the position facing the air path to form part of the air path. Therefore, when the air is suctioned from the axially central portion of the fan casing in response to the rotation of the impeller and delivered from the air path provided radially outward, the bearing holding portion is cooled to enable the enhancement of heat dissipation of the bearings.

Furthermore, there is no need to change a material for the fan casing to enhance the heat dissipation; therefore, it is possible to avoid a great increase in the weight of the blower and prevent a great increase in a temperature of the delivered air.

A tip end side of a flange portion of the bearing holding portion extending radially outward to the air path, which is disposed radially outward about the motor shaft, may form part of the air path.

This can release the heat generated from the bearings to the air path through the flange portion provided in the bearing holding portion, enhance the heat dissipation of the bearings, and achieve extended lifespan.

The flange portion may be formed integrally with the bearing holding portion or may be separately assembled to the bearing holding portion by a combination of separate elements.

Integrating the flange portion with the bearing holding portion can reduce the number of parts and improve rigidity. Furthermore, separately forming the flange portion from the bearing holding portion may increase the number of parts but improve yield.

In this way, the bearing holding portion made of metal can improve heat conductivity and accelerate the heat dissipation of the bearings through the flange portion.

The impeller may include a plurality of first blades formed standing on one surface of a rotating plate facing an intake opening portion; and a plurality of second blades formed standing on the other surface of the rotating plate facing the flange portion.

In this way, the plurality of second blades also formed standing on the other surface of the rotating plate facing the flange portion can enhance the heat dissipation of the bearings through the flange portion and offset the stress of trying to float along the axial direction of the bearing holding portion.

The bearing holding portion may be assembled to the fan casing via an anti-vibration member.

In this way, the rotation vibration of the motor shaft to which the impeller and the rotor are assembled can be absorbed by the anti-vibration member and prevented from propagating to the fan casing.

Moreover, a gap may be provided between the flange portion of the bearing holding portion facing the air path and the fan casing. In this case, the blower is structured to suppress airflows around the bearings from leaking to the air path by the anti-vibration member. This can facilitate the release of hot air around the bearings to the air path via the gap between the flange portion of the bearing holding portion and the fan casing through the flange portion.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a blower capable of improving the heat dissipation of bearings disposed between an impeller and a motor and achieving extended lifespan without increasing the number of parts.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of a blower according to a first embodiment.

FIG. 2 is a cross-sectional view of a blower according to a second embodiment.

FIG. 3 is a cross-sectional view of a conventional blower.

DESCRIPTION OF EMBODIMENTS

First Embodiment

Embodiments of a blower according to the present invention will be described hereinafter with reference to the accompanying drawings. Schematic configurations of the blower will first be described with reference to FIG. 1.

As illustrated in FIG. 1, a blower 1 has an integral assembly of a fan casing 3, which accommodates an impeller 2, and a motor casing 5, which accommodates a motor 4 that drives the impeller 2 to rotate. While a DC brushless motor is used as the motor 4, and an inner-rotor type motor is used in the present embodiment. When the motor 4 drives the impeller 2 to rotate, air is suctioned from an axially central portion of the fan casing 3 and delivered from an annular air path 6 provided radially outward.

The motor casing 5 accommodates the inner-rotor type motor 4. Specifically, a stator 7 is assembled to an inner wall surface of the motor casing 5. The stator 7 is configured so that an annular core back portion 7b of a stator core 7a is press-fitted. The stator core 7a may be fixed by adhesive bonding instead of press-fit. A plurality of pole teeth 7c protrude radially inward from the core back portion 7b. The stator core 7a is covered with an insulator 7d, and a motor coil 7e is wound around the pole teeth 7c via the insulator 7d.

A rotor 8 is configured so that a cylindrical yoke 8b is assembled to one end side (lower end side in FIG. 1) of a motor shaft 8a around the motor shaft 8a and that an annular rotor magnet 8c is assembled concentrically to an outer circumference of the yoke 8b. The rotor magnet 8c is magnetized to alternately form N poles and S poles circumferentially.

Furthermore, the insulator 7d provided near a bottom portion 5a of the motor casing 5 is supported on a motor substrate 7f. A lead wire of the motor coil 7e is connected to the motor substrate 7f, and a feeder circuit for the motor coil 7e is provided above the motor substrate 7f. A magnetic sensor 7g (such as a Hall IC) is also provided on the motor substrate 7f. A holder 8d formed from a non-magnetic material is assembled to the yoke 8b on a shaft end of the motor shaft 8a, and an annular sensor magnet 8e is assembled to the holder 8d to be opposed to the magnetic sensor 7g. The sensor magnet 8e is magnetized to correspond to a magnetic pole of the rotor magnet 8c, and a current-carrying direction in which a current flows in the motor coil 7e is switched in response to the magnetic pole detected by the magnetic sensor 7g. A connecting wire 7h is connected to the motor substrate 7f, and the connecting wire 7h is spread along the bottom portion 5a of the motor casing 5. The connecting wire 7h is led out of the motor casing 5 via a grommet 7i assembled to the motor casing 5.

Moreover, the other end side (upper end side in FIG. 1) of the motor shaft 8a extends into the fan casing 3, and the impeller 2 is integrally assembled to a shaft end of the motor shaft 8a via an insert sleeve 8f. The impeller 2 includes a plurality of first blades 2b formed standing on an upper surface of a disc-shaped rotating plate 2a from a central portion through an outer circumferential portion of the rotating plate 2a. Second blades 2c are also formed standing on a lower surface of the rotating plate 2a near the outer circumferential portion. In this way, the plurality of second blades 2c also formed standing on the lower surface of the rotating plate 2a can enhance heat dissipation of bearings 10, to be described later, and offset a stress of trying to float along an axial direction of a bearing holding portion 11. The second blades 2c are not necessarily provided and may be omitted depending on the product.

Furthermore, the fan casing 3 is formed from a combination of a first casing 3a and a second casing 3b. An intake opening portion 3c is provided in a central portion of the first casing 3a, and an air path radially outward along the first blades 2b is formed between an inner wall surface of the first casing 3a and the rotating plate 2a of the impeller 2. A center of the intake opening portion 3c does not necessarily coincide with an axis of the motor shaft 8a and may be present in a range in which a position of the intake opening portion 3c is near an axially central portion of the fan casing 3 and the blower 1 can operate without efficiency reduction. A first curved portion 3d curved to have a recess inner wall surface continuous with the air path is provided around an outer circumference of the first casing 3a.

The second casing 3b is disposed to be opposed to the first casing 3a on an outer circumference of the first casing 3a, and a second curved portion 3e curved to have a recess inner wall surface is provided around the second casing 3b to be opposed to the first curved portion 3d. The recessed surface of the first curved portion 3d is combined with the recessed surface of the second curved portion 3e to form the annular air path 6. An outer circumferential end portion 2d of the rotating plate 2a of the impeller 2 extends to a position facing the air path 6 near the first curved portion 3d. The first casing 3a and the second casing 3b are assembled by fitting a projecting portion into a recess portion provided in outer circumferential end portions of the first curved portion 3d and the second curved portion 3e.

An annular fitting wall 3f protrudes from the second casing 3b, and this fitting wall 3f is fitted into an opening portion 5b of the motor casing 5 to assemble the fan casing 3 and the motor casing 5. In addition, an annular seal wall 3g protrudes radially outward from the second casing 3b to be side by side with the fitting wall 3f. A seal member (O-ring) 9 is put between the seal wall 3g and an outer wall 5c of an opening of the motor casing 5 to close connections between the fan casing 3 and the motor casing 5. It is noted that the fan casing 3 and the motor casing 5 are assembled to be integral by superimposing corresponding screw holes on each other and fitting a screw, not illustrated, into the screw holes.

A pair of bearings 10 (rolling bearings) are assembled between the impeller 2 and the rotor 8 assembled to respective end portions of the motor shaft 8a. The pair of bearings 10 are held by the bearing holding portion 11 and rotatably support the motor shaft 8a. The bearing holding portion 11 is a cylindrical metal body of high heat conductivity (e.g., stainless steel), and the pair of bearings 10 are assembled into a cylindrical hole. The motor shaft 8a is assembled by inserting the pair of bearings 10 and rotatably supported by the pair of bearings 10.

The bearing holding portion 11 is disposed adjacent to the impeller 2, and a flange portion 11a provided in an end portion of the bearing holding portion 11 near the impeller 2 extends radially outward. The flange portion 11a is disposed to be opposed to the rotating plate 2a of the impeller 2, parts near an outer circumferential end portion 11b of the flange portion 11a extend to a position facing the air path 6 to form part of the air path 6. This can release the heat generated from the pair of bearings 10 to the air path 6 through the flange portion 11a provided in the bearing holding portion 11, enhance the heat dissipation of the bearings 10, and achieve extended lifespan. The outer circumferential end portion 11b of the flange portion 11a tapers to have a tapered surface. A curved surface along the air path 6 may be formed as an alternative to the tapered surface. In the present embodiment, the flange portion 11a is assembled to the bearing holding portion 11 by assembling a combination of a plurality of annular portions. Specifically, an annular first flange portion 11a1 formed integrally with a main body of the bearing holding portion 11 and an annular second flange portion 11a2 superimposed on the first flange portion 11a1 are assembled by superimposing stepped portions on each other. In this way, configuring the flange portion 11a from the two parts can save manufacturing costs without wasting a metal material.

An annular flange portion 3h protrudes radially inward on a side wall surface of an inner circumference of the second curved portion 3e of the second casing 3b. The flange portion 11a of the bearing holding portion 11 is superimposed on one axial surface side (upper surface side) of this flange portion 3h via an anti-vibration member 12 (e.g., rubber). Furthermore, a cylindrical metal collar 13 is inserted into a central hole of the flange portion 3h covered with the anti-vibration member 12, and a flange portion 13a of the collar 13 is superimposed on the other axial surface side (lower surface side) of the flange portion 3h. In this way, a nut 14 is screwed into a screw portion 11c provided on an outer circumferential surface of the bearing holding portion 11 with the flange portion 3h put between the flange portion 11a of the bearing holding portion 11 and the flange portion 13a of the collar 13 in the axial direction via the anti-vibration member 12, thus fixing an assembly position of the bearing holding portion 11 with respect to the motor shaft 8a. In this way, the anti-vibration member 12 interposed between the bearing holding portion 11 and the fan casing 3 can absorb a rotational vibration of the motor shaft 8a to which the impeller 2 and the rotor 8 are assembled, to prevent the rotational vibration from propagating to the fan casing 3.

As described above, the outer circumferential end portion 2d of the flange portion 11a of the bearing holding portion 11 adjacent to the impeller 2 extends to the position facing the air path 6 and forms part of the air path 6. Therefore, when the air is suctioned from the axially central portion of the fan casing 3 by the rotation of the impeller 2 and compressed air is delivered from the air path 6 provided radially outward, the bearing holding portion 11 is cooled through the metal flange portion 11a to enable enhancement of the heat dissipation of the bearings 10.

Furthermore, there is no need to change the material for the fan casing 3 to a metal material with high heat conductivity to enhance heat dissipation. Therefore, it is possible to avoid a great increase in a weight of the blower 1 and prevent a great increase in a temperature of the delivered air.

Furthermore, a gap 15 may be provided between the flange portion 11a facing the air path 6 and the fan casing 3 (second casing 3b). While the blower 1 is structured so that the anti-vibration member 12 can suppress the leakage of airflows around the bearings 10 to the air path 6, this structure can facilitate the release of hot air around the bearings 10 to the air path 6 via the gap 15 through the flange portion 11a of the bearing holding portion 11.

An experiment was conducted to measure a temperature difference in the bearing holding portion 11 between the conventional structure illustrated in FIG. 3 and the structure of the first embodiment illustrated in FIG. 1 after the blower 1 was driven to rotate in the same conditions. It turned out that the configurations of the first embodiment were lower in temperature by about 7.3° C. and produced a sufficient cooling effect on the bearings 10 and the bearing holding portion 11.

Second Embodiment

Another embodiment of the blower 1 according to the present invention will be described with reference to FIG. 2. The motor casing 5 that configures the blower 1 and that accommodates the motor 4 and the fan casing 3 that configures the blower 1 and that accommodates the impeller 2 are similar in configurations to those in the first embodiment. The same reference signs denote the same members, and descriptions of the same members in the first embodiment shall apply to the second embodiment.

In FIG. 2, the pair of bearings 10 provided between the impeller 2 and the rotor 8 are held by the bearing holding portion 11 made of metal with high heat conductivity (e.g., stainless steel), and the pair of bearings 10 rotatably support the motor shaft 8a. This structure is similar to that illustrated in FIG. 1. The bearing holding portion 11 is disposed adjacent to the impeller 2, the flange portion 11a extending radially outward from the bearing holding portion 11 is disposed to be opposed to the rotating plate 2a of the impeller 2, and parts near the outer circumferential end portion 11b of the flange portion 11a form part of the air path 6. These configurations are also similar to those in the first embodiment.

The present embodiment differs from the first embodiment in that the flange portion 11a is not formed from the two parts but is formed integrally with the bearing holding portion 11. Integrating the flange portion 11a with the bearing holding portion 11 can reduce the number of parts and improve rigidity.

As described so far, the bearing holding portion 11 made of metal can improve the heat conductivity and accelerate the heat dissipation of the bearings 10 through the flange portion 11a. Therefore, it is possible to provide the blower 1 capable of improving the heat dissipation of the bearings 10 disposed between the impeller 2 and the motor 4 and achieving extended lifespan without increasing the number of parts.

Claims

1. A blower comprising an integral assembly of a fan casing accommodating an impeller and a motor casing accommodating a motor that drives the impeller to rotate, for suctioning air from an axially central portion of the fan casing and delivering the air from an air path provided radially outward, wherein a bearing rotatably supporting a motor shaft to which a rotor of the motor and the impeller are assembled on two longitudinal sides, respectively, and a metal bearing holding portion holding the bearing are disposed between the impeller and the motor, and the bearing holding portion extends radially outward to a position facing the air path and forms part of the air path.

2. The blower according to claim 1, wherein a tip end side of a flange portion of the bearing holding portion extending radially outward to the air path, which is disposed radially outward about the motor shaft, forms part of the air path.

3. The blower according to claim 2, wherein the flange portion is formed integrally with the bearing holding portion.

4. The blower according to claim 2, wherein the flange portion is assembled to the bearing holding portion by combining a plurality of annular portions.

5. The blower according to claim 1, wherein the impeller comprises a plurality of first blades formed standing on one surface of a rotating plate facing an intake opening portion; and a plurality of second blades formed standing on the other surface of the rotating plate facing the flange portion.

6. The blower according to claim 1, wherein the bearing holding portion is assembled to the fan casing via an anti-vibration member.

7. The blower according to claim 6, wherein a gap is provided between the flange portion of the bearing holding portion facing the air path and the fan casing.