WO2015063882A1

WO2015063882A1 - Electric motor and bearing structure

Info

Publication number: WO2015063882A1
Application number: PCT/JP2013/079385
Authority: WO
Inventors: 後藤　隆
Original assignee: 三菱電機株式会社
Priority date: 2013-10-30
Filing date: 2013-10-30
Publication date: 2015-05-07
Also published as: JP5885896B2; CN205509736U; JPWO2015063882A1

Abstract

A sleeve (20) which is installed between a motor housing (6) (or a bearing housing (7)) and an outer ring (12) of a ball bearing (10), said sleeve comprising a cylindrical resin member (21) and a metal member (22) which covers at least the inner and outer peripheral surfaces of the resin member (21). The metal member (22) is in surface contact with both the motor housing (6) (or the bearing housing (7)) and the outer ring (12) of the ball bearing (10).

Description

Electric motor and bearing structure

The present invention relates to an electric motor and a bearing structure that rotatably support a shaft using a grease-filled ball bearing.

High-speed rotation bearings are widely used for machine tools and automobiles. The most common bearing is a grease-enclosed ball bearing having a configuration in which grease is enclosed by interposing a plurality of balls between an inner ring and an outer ring. Since bearings used for high-speed rotation have high internal heat generation, extending the life of durability has become an important issue.

To ensure the life of the bearing, change the internal structure of the bearing (for example, reduce the contact area between the ball and the raceway surface), change the bearing material (for example, reduce the kinematic viscosity of the grease and heat resistance of the grease itself) To improve heat dissipation). Further, when the bearing is used in a product, a heat radiating material is attached to the bearing (for example, see Patent Document 1), or a heat pipe is used for a shaft for fixing the inner ring of the bearing (for example, see Patent Document 2) The pulley is integrally formed with the outer ring of the bearing (see, for example, Patent Document 3) to ensure heat dissipation.

On the other hand, when a rotating member (hereinafter referred to as a shaft) is rotatably supported using a bearing, it is necessary to consider the vibration of the shaft itself. For example, if the natural frequency of the shaft and the natural frequency of the product itself resonate and resonate, the vibration amplitude is amplified, causing damage to the internal components. In order to attenuate the vibration of the shaft rotating at high speed, it was necessary to set the natural frequency of the shaft itself as high as possible.

In order to set the natural frequency of the shaft high, it is necessary to increase the rigidity of the shaft (shorter and thicker), but for the convenience of the product (for example, cost reduction, weight reduction, volume reduction), the shaft In some cases, it was difficult to set the natural frequency high. In that case, in order to increase the natural frequency of the shaft or reduce the resonance magnification of the shaft, a tolerance ring is attached to the bearing (for example, see Patent Document 4), or an O-ring is attached (for example, Patent Document) 5), a high vibration damping metal is installed (see, for example, Patent Document 6), and vibration is attenuated.

JP 2012-149742 A JP 2013-57300 A JP 2010-90969 A Special table 2010-525276 Special table 2010-535969 gazette JP 2004-251417 A

Here, consider the case where the configurations of Patent Documents 1 to 6 are applied to an electric motor.
In the case of

Patent Documents

1 and 2, when the bearing is press-fitted into the shaft, the housing side is fitted with a gap, so there is an air layer between the bearing and the housing, and a heat dissipation path from the bearing to the housing cannot be secured.
In the case of Patent Document 3, since the bearing and the resin housing are integrally formed, there is no air layer between the bearing and the resin housing, and heat transfer is not hindered, but since the final heat dissipation path is made of resin, the heat dissipation rate is low. When a housing is constructed using a high heat-dissipating resin, an improvement in the heat dissipation rate is expected, but the cost increases.
In Patent Documents 1 to 3, the effect of vibration damping cannot be expected.

In the case of Patent Document 4, a tolerance ring is installed between the bearing and the housing to attenuate the vibration. However, since the tolerance ring is in line contact, the heat radiation effect of the bearing is low.
In the case of Patent Document 5, an O-ring is installed between the bearing and the housing to attenuate the vibration. However, since the O-ring is in line contact, the heat dissipation effect of the bearing is low. Moreover, since the compressive stress of an O-ring is applied to an axial direction at the time of an assembly, an assemblability deteriorates.
In the case of Patent Document 6, a high vibration damping metal is installed between the bearing and the housing to attenuate the vibration. However, the high vibration damping metal has a characteristic that the vibration damping effect is greatly reduced at a high temperature. It is necessary to interpose a low heat conductive member between the high vibration damping metals, and a heat dissipation path from the bearing to the housing cannot be secured.

As described above, the configurations of Patent Documents 1 to 6 have a problem that only one of the effects of heat dissipation and vibration attenuation can be expected. Therefore, in order to obtain the effects of both heat dissipation and vibration attenuation, the heat dissipation structure disclosed in Patent Documents 1 to 3 and the vibration attenuation structure disclosed in Patent Documents 4 to 6 are used in combination. Deterioration of quality and cost increase.

The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a bearing structure capable of easily obtaining heat dissipation and vibration damping effects, and an electric motor using the bearing structure.

The electric motor of the present invention comprises a cylindrical resin member and a metal member that covers at least the inner and outer peripheral surfaces of the resin member, and is installed between the outer ring and the housing of the ball bearing, and the metal member is the outer ring and the housing of the ball bearing. And a sleeve each in surface contact.

A bearing structure according to the present invention includes a grease-enclosed ball bearing that rotatably supports a first member fixed to the inner ring side and a second member fixed to the outer ring side, a cylindrical resin member, and It consists of a metal member that covers at least the inner and outer peripheral surfaces of the resin member, is installed between the outer ring of the ball bearing and the second member, and the metal member makes surface contact with the outer ring and the second member of the ball bearing, respectively. And a sleeve.

According to this invention, the resin member mainly responsible for the vibration damping function of the shaft and the metal member mainly responsible for the heat radiation function of the ball bearing are integrated to constitute the sleeve, thereby easily obtaining the effects of vibration damping and heat radiation. It is done. Furthermore, the heat dissipation from the ball bearing through the sleeve to the housing can be improved by bringing the metal member into surface contact with the ball bearing and the housing.

According to the present invention, the resin member mainly responsible for the vibration damping function of the first member and the metal member mainly responsible for the heat radiation function of the ball bearing are integrated to constitute the sleeve, so that vibration damping and heat radiation can be easily performed. An effect is obtained. Furthermore, the heat dissipation from the ball bearing through the sleeve to the second member can be improved by bringing the metal member into surface contact with the ball bearing and the second member.

It is sectional drawing which shows the structure of the electric motor which concerns on Embodiment 1 of this invention. It is the figure which expanded the structure in A frame of FIG. 4 is a graph showing a resonance curve of a sleeve used in the electric motor according to Embodiment 1. 4 is a graph showing a resonance curve of a sleeve used in the electric motor according to Embodiment 1.

Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
As shown in FIG. 1, an electric motor 1 includes a motor housing 6 that houses an electric motor body 2, a grease-enclosed ball bearing 10 that rotatably supports a shaft 3, and a bearing housing 7 that houses one ball bearing 10. And a sleeve 20 attached to the outer ring 12 side of the ball bearing 10.

The electric motor main body 2 mainly includes a shaft 3, a rotor 4 fixed to the shaft 3, and a stator 5 installed in a motor housing 6 so as to surround the rotor 4. Other configurations (coils, etc.) are not shown. The motor body 2 is assumed to have a motor structure for high speed rotation (for example, a magnetic inductor type motor structure) having a rotation speed of about 30,000 rpm to 100,000 rpm, but is not limited to this. It is not a thing.

The two ball bearings 10 are fitted into both ends of the shaft 3 so as to support the shaft 3 (first member) and the housings 6 and 7 (second member) in a relatively rotatable manner. This ball bearing 10 is formed by interposing a plurality of balls 13 between an inner ring 11 and an outer ring 12 and enclosing grease. The inner ring 11 is in contact with the shaft 3, and the outer ring 12 is in contact with the sleeve 20 on the motor housing 6 side or the bearing housing 7 side. The ball bearing 10 installed on the motor housing 6 is urged by the pressurizing spring 9 and fixed in the axial direction.

Since the ball bearing 10 used in the motor body 2 for high-speed rotation has high internal heat generation, it is important to ensure heat dissipation. It is also necessary to attenuate the vibration of the shaft 3 that rotates at high speed. Therefore, in the first embodiment, the sleeve 20 having the functions of heat dissipation and vibration damping is used.

2, the sleeve 20 includes a cylindrical resin member 21 and a metal member 22 that covers at least the inner and outer peripheral surfaces of the resin member 21. The metal member 22 is manufactured into an annular shape with a U-shaped cross section by cutting or pressing (drawing), and a resin material is injected into the inside thereof to form the resin member 21. By controlling the amount of injected resin at the time of injection, the occurrence of a gap between the metal member 22 and the resin member 21 is prevented. This is because when the gap is generated, the heat transfer efficiency of the sleeve 20 is deteriorated.

The sleeve 20 is press-fitted into and fitted into the ball bearing 10 so that the inner peripheral surface side of the metal member 22 is in surface contact with the outer ring 12 of the ball bearing 10 and the outer peripheral surface side of the metal member 22 is connected to the motor housing 6 or the bearing housing. 7 is brought into surface contact. By press-fitting the sleeve 20 and the ball bearing 10, it is possible to prevent a gap from being generated in the surface contact portion. Further, since the sleeve 20 is in surface contact, the heat transfer efficiency between the ball bearing 10, the sleeve 20, and the motor housing 6 (or the bearing housing 7) is improved, and heat dissipation is improved.

The motor housing 6 and the bearing housing 7 are made of aluminum having high thermal conductivity, and are manufactured by die casting, for example. In addition, it is desirable to improve the heat dissipation by providing heat radiating fins 6 a on the outer peripheral portion of the motor housing 6 that faces the sleeve 20. Similarly, it is desirable to improve the heat dissipation by providing heat radiating fins 7 a on the outer peripheral portion of the bearing housing 7 facing the sleeve 20.
Although not shown, a water cooling path or the like may be provided in the motor housing 6 and the bearing housing 7 to improve heat dissipation.

Most of the heat generated by the ball bearing 10 is transferred to the motor housing 6 via the metal member 22 (heat transfer path B1 in FIG. 2) and radiated from the heat radiation fins 6a (heat radiation path C in FIG. 2). .
Further, part of the heat generated by the ball bearing 10 is transferred to the motor housing 6 through the metal member 22 on the outer ring 12 side, the resin member 21, and the metal member 22 on the motor housing 6 side (the heat transfer in FIG. 2). The heat is radiated from the heat radiation fin 6a (path B2) (heat radiation path C in FIG. 2).
Although illustration is omitted, the ball bearing 10 installed in the bearing housing 7 also constitutes a similar heat transfer path and heat dissipation path.

Here, details of the sleeve 20 will be described.
The resin member 21 has a cylindrical shape that surrounds the ball bearing 10. The resin member 21 mainly has a function of attenuating the vibration of the shaft 3, and the vibration damping effect can be adjusted by changing the resin material (or rubber material) and changing the hardness. For example, when a damping effect is added to a silicon-based or butyl-based rubber material (polymer material), carbon (carbon) and a resin filler are added to the base rubber material. At that time, the magnitude of the vibration damping effect can be changed by increasing or decreasing the amount of addition.
For this reason, it is possible to manage the vibration damping property without changing the shape of the sleeve 20.

3 and 4 show the resonance curve of the sleeve 20. In each graph, the horizontal axis represents frequency, and the vertical axis represents resonance magnification. In FIG. 3, when the hardness of the resin member 21 is increased, the resonance curve changes from L0 to L1, and the resonance frequency (natural frequency) increases from f0 to f1. On the other hand, in FIG. 4, when the hardness of the resin member 21 is lowered, the resonance curve changes from L0 to L2, and the resonance magnification decreases from p0 to p2.
Therefore, the vibration damping property can be adjusted by changing the hardness of the resin member 21 in accordance with the frequency of the shaft 3 as a vibration source and adjusting either or both of the resonance frequency and the resonance magnification.

Further, since the temperature of the sleeve 20 rises due to the heat generated by the ball bearing 10, it is desirable to use a thermosetting resin material for the resin member 21.
Furthermore, in order to improve the heat dissipation through the heat transfer path B2 shown in FIG. 2, it is desirable to use a resin material having a heat dissipation of at least 0.3 W / mK for the resin member 21.
The heat radiation effect can be adjusted by changing the resin material (or rubber material) of the resin member 21.
Generally, when a resin material (polyphenylene sulfide; PPS, nylon, epoxy) has a high heat dissipation, a high thermal conductive filler is added to the base resin material. In that case, the magnitude of the heat dissipation effect can be changed by increasing or decreasing the addition amount.
For this reason, heat dissipation can be managed without accompanying the shape change of the sleeve 20.

On the other hand, the metal member 22 of the sleeve 20 is an annular member having a U-shaped cross section in the rotation axis direction of the shaft 3 and covers the resin member 21. The metal member 22 mainly has a function of transferring heat generated by the ball bearing 10 to the motor housing 6 or the bearing housing 7 to dissipate the heat, and is configured using a metal material having thermal conductivity.
The metal member 22 is desirably made of a metal material (for example, spring steel material) having lower rigidity than the outer ring 12 of the ball bearing 10. Thereby, when the sleeve 20 is press-fitted into the ball bearing 10, the deformation of the outer ring 12 of the ball bearing 10 is suppressed, and the internal gap of the ball bearing 10 is not reduced.

Further, the chamfered portion 23 is provided by performing C chamfering or R chamfering on the inner peripheral edge of the metal member 22 on the U-shaped opening side. The chamfered portion 23 functions as a guide when the sleeve 20 is press-fitted into the ball bearing 10. Thereby, the assembling property of the sleeve 20 is improved.

Furthermore, a polygonal portion 25 is provided by bending the inner peripheral edge of the metal member 22 on the U-shaped bent portion 24 side at a plurality of locations. Since the polygonal portion 25 is positively deformed when the sleeve 20 is press-fitted into the ball bearing 10 and absorbs the stress applied to the bent portion 24, the surface contact between the metal member 22 and the outer ring 12 can be ensured.

Next, an example of the assembly procedure of the electric motor 1 will be described. In this example, the motor housing 6 side and then the bearing housing 7 side are assembled first, but the reverse procedure may be used.
First, the sleeve 20 is press-fitted into the ball bearing 10 on the motor housing 6 side, and the sleeve 20 is press-fitted into the motor housing 6. Subsequently, the pressurizing spring 9 is installed on one end face of the ball bearing 10, and the pressurizing spring 9 is positioned by the inner diameter of the sleeve 20. Subsequently, the shaft 3 is fitted into the ball bearing 10 with a gap. As a result, the ball bearing 10, the sleeve 20, and the shaft 3 are assembled to the motor housing 6.

Subsequently, a sleeve 20 is press-fitted into the ball bearing 10 on the bearing housing 7 side, and this sleeve 20 is press-fitted into the bearing housing 7. Subsequently, the shaft 3 assembled to the motor housing 6 is fitted into the ball bearing 10 on the bearing housing 7 side with a gap. Finally, the butted portion of the bearing housing 7 and the motor housing 6 is fastened with a band 8 (or a bolt or the like).

As described above, according to the first embodiment, the sleeve 20 includes the cylindrical resin member 21 and the metal member 22 that covers at least the inner and outer peripheral surfaces of the resin member 21, and the outer ring 12 of the ball bearing 10 and the motor housing 6 ( Alternatively, the metal member 22 is installed between the bearing housing 7) and the outer surface 12 of the ball bearing 10 and the motor housing 6 (or the bearing housing 7). For this reason, the effect of heat dissipation and vibration damping can be easily obtained with one component. Further, since the metal member 22 is in surface contact with the outer ring 12 of the ball bearing 10 and the motor housing 6 (or the bearing housing 7), heat dissipation through the heat transfer path B2 (shown in FIG. 2) is improved.

Further, according to the first embodiment, the metal member 22 of the sleeve 20 has a U-shaped cross section in the rotation axis direction of the shaft 3, and the bent portion 24 of the U shape is bent at a plurality of locations to form a polygonal portion. 25.
For this reason, the heat of the ball bearing 10 can be efficiently radiated through the heat transfer path B1 (shown in FIG. 2) formed by the metal member 22 having a U-shaped cross section. Further, when the sleeve 20 is press-fitted into the ball bearing 10, the polygonal portion 25 is positively deformed and absorbs stress applied to the inner peripheral surface of the metal member 22, so that the metal member 22 and the outer ring 12 of the ball bearing 10 are absorbed. Can be ensured.

Further, according to the first embodiment, the sleeve 20 can adjust either one or both of the resonance magnification and the resonance frequency by changing one or both of the material and the hardness of the resin member 21. did. Thereby, the vibration damping property can be improved without changing the shape of the sleeve 20.

Further, according to the first embodiment, since the resin member 21 of the sleeve 20 is made of a resin material having a heat dissipation property, the heat dissipation property can be improved without changing the shape of the sleeve 20.

Further, according to the first embodiment, since the sleeve 20 is formed by injecting the thermosetting resin member 21 into the metal member 22, there is no gap between the metal member 22 and the resin member 21, and high transmission is achieved. Thermal efficiency can be obtained. Moreover, by using the thermosetting resin member 21, it is not necessary to block the opening of the metal member 22 having a U-shaped cross section.
A moisture curable resin may be used as the resin member 21.

Further, according to the first embodiment, since the sleeve 20 is press-fitted between the outer ring 12 of the ball bearing 10 and the motor housing 6 (or the bearing housing 7), the sleeve 20 can be closely adhered. Therefore, the heat of the ball bearing 10 can be efficiently radiated from the motor housing 6 (or the bearing housing 7) to the outside via the sleeve 20.

Further, according to the first embodiment, since the motor housing 6 and the bearing housing 7 are made of aluminum having high thermal conductivity, heat can be efficiently radiated.

In the above description, the example in which the bearing structure including the ball bearing 10 and the sleeve 20 is applied to the electric motor 1 has been described. However, the present invention can be applied to a machine tool or the like.

In the present invention, any component of the embodiment can be modified or any component of the embodiment can be omitted within the scope of the invention.

As described above, the bearing structure according to the present invention is suitable for use in an electric motor for high-speed rotation and the like because a sleeve having an effect of heat dissipation and vibration damping is installed between the grease-enclosed ball bearing and the housing. Yes.

1 electric motor, 2 electric motor body, 3 shaft (first member), 4 rotor, 5 stator, 6 motor housing (second member), 6a, 7a radiating fin, 7 bearing housing (second member), 8 bands, 9 pressure springs, 10 ball bearings, 11 inner rings, 12 outer rings, 13 balls, 20 sleeves, 21 resin members, 22 metal members, 23 chamfered parts, 24 bent parts, 25 polygonal parts.

Claims

A shaft to which the rotor is fixed;
A housing in which a stator is installed so as to surround the rotor;
In an electric motor comprising a grease-enclosed ball bearing that rotatably supports the shaft with respect to the housing,
A cylindrical resin member and a metal member that covers at least the inner and outer peripheral surfaces of the resin member, are installed between the outer ring of the ball bearing and the housing, and the metal member is formed between the outer ring of the ball bearing and the housing. An electric motor comprising a sleeve that is in surface contact with each other.
2. The electric motor according to claim 1, wherein the metal member of the sleeve has a U-shaped cross section in the rotation axis direction of the shaft, and a bent portion of the U-shape is a polygonal shape.
2. The sleeve according to claim 1, wherein either or both of a resonance magnification and a resonance frequency are adjusted by changing either or both of the material and hardness of the resin member. Electric motor.
2. The electric motor according to claim 1, wherein the resin member of the sleeve has a heat dissipation property.
2. The electric motor according to claim 1, wherein the sleeve is formed by injecting the resin member having heat or moisture curing property into the metal member.
2. The electric motor according to claim 1, wherein the sleeve is press-fitted between an outer ring of the ball bearing and the housing.
The electric motor according to claim 1, wherein the housing is made of aluminum.
A grease-enclosed ball bearing that rotatably supports a first member fixed to the inner ring side and a second member fixed to the outer ring side;
It consists of a cylindrical resin member and a metal member that covers at least the inner and outer peripheral surfaces of the resin member, and is installed between the outer ring of the ball bearing and the second member, and the metal member is connected to the outer ring of the ball bearing. A bearing structure comprising a sleeve that is in surface contact with each of the second members.