JP7480735B2 - Housing structure of rotating electric machine and rotating electric machine - Google Patents

Description

The present invention relates to a housing structure for a rotating electric machine and a rotating electric machine.

Conventionally, in the housing structure of a rotating electric machine, a configuration is known in which the rotating body is supported by two bearings, one of which is a fixed end to which the bearing outer ring is fixed, and the other bearing is a free end to which the bearing outer ring is not fixed. In addition, in this type of housing structure for a rotating electric machine, a preload spring is generally installed between the bearing on the free end side and the housing surface facing the bearing to apply a preload to the bearing outer ring.

In Patent Document 1, a preload spring is installed between the bearing on the free end side and the housing surface facing the bearing, and a preload is applied to the bearing outer ring. Furthermore, Patent Document 1 is configured to form a gap between the bearing outer ring and the inner peripheral surface of the housing facing the bearing outer ring, improving assembly and removal when attaching and detaching the bearing.

Japanese Patent Application Laid-Open No. 5-64390

However, in the above-mentioned Patent Document 1, when the rotating electric machine is driven, there is a possibility that the rotating shaft may tilt by the amount of the gap between the outer ring of the bearing and the inner peripheral surface of the housing facing the outer ring of the bearing at the free end side where the outer ring of the bearing is not fixed.

When the rotating shaft tilts, the bearing also tilts, causing the corners of the outer ring of the bearing to come into contact with the inner surface of the housing facing the outer ring, and the stress on the housing becomes high around the contact point. If the rotating electric machine continues to be used (driven) in this state, the contact points between the corners of the outer ring of the bearing and the inner surface of the housing will be damaged and scraped off, and the resulting cutting debris will cause abnormal noise when the rotating electric machine is running.

The present invention was made in consideration of the above situation, and aims to provide a housing structure for a rotating electric machine that can prevent damage to the housing even if the bearing is tilted.

One aspect of the present invention is a casing structure for a rotating electric machine, comprising a housing that houses a rotor and a stator and through which a rotating shaft is inserted, and a first bearing that rotatably supports one side of the rotating shaft and is loosely fitted into the housing, the housing having an inner circumferential surface facing the outer circumferential surface of the first bearing and a bearing holder that receives the first bearing, the inner circumferential surface of the bearing holder being cut out in the circumferential direction to form a cutout that receives an outer circumferential corner of the first bearing when the rotating shaft is tilted radially.

In the above-mentioned rotating electric machine housing structure, the cutout portion may be formed in a concave shape. In the above-mentioned rotating electric machine housing structure, multiple corners of the cutout portion may be chamfered.

In the above-mentioned rotating electric machine housing structure, a predetermined gap may be formed between the outer peripheral surface of the first bearing and the inner peripheral surface of the housing. In the above-mentioned rotating electric machine housing structure, a pressure spring may be arranged between one end face of the first bearing in the axial direction of the rotating shaft and an end face of the housing facing the one end face of the first bearing. In the above-mentioned rotating electric machine housing structure, a second bearing may be provided that is fixed to the housing and rotatably supports the other side of the rotating shaft.

A rotating electric machine according to another aspect of the present invention includes the above-mentioned rotating electric machine housing structure, a rotor and a stator housed in the housing, and a rotating shaft inserted into the housing.

The present invention provides a housing structure for a rotating electrical machine that can prevent damage to the housing even if the bearing is tilted.

1 is a cross-sectional view showing an example of the configuration of a rotating electric machine according to an embodiment of the present invention; 1 is a diagram showing a housing structure of a rotating electric machine according to an embodiment of the present invention; 2 is an enlarged view of a housing structure of the rotating electric machine according to the embodiment; FIG. 2 is a cross-sectional perspective view of the periphery of a bearing on a free end side of the rotating electric machine according to the embodiment; FIG. 13 is a diagram showing a state in which the bearing on the free end side is tilted in this embodiment. FIG. FIG. 11 is a perspective view showing a housing structure of a rotating electric machine in a comparative example. 13 is a diagram showing a state in which a bearing on the free end side of a rotating electric machine in a comparative example is tilted. FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In the embodiments, in order to make the description easier to understand, structures and elements other than the main parts of the present invention will be described in a simplified or omitted manner. In addition, in the drawings, the same elements are given the same reference numerals. Note that the shapes, dimensions, etc. of each element shown in the drawings are shown only for illustrative purposes, and do not represent the actual shapes, dimensions, etc.

FIG. 1 is a cross-sectional view showing an example of the configuration of a rotating electrical machine 1 according to the present embodiment.
The rotating electric machine 1 of this embodiment is a motor that is mounted on a vehicle or the like and used as an electric motor or a generator.

The rotating electric machine 1 of this embodiment includes a cylindrical housing (frame) 10 and a rotating shaft (shaft) 13 rotatably supported by the housing 10 via a bearing 11. The bearing 11 is composed of an outer ring, an inner ring, and a plurality of rolling elements that roll between the outer ring and the inner ring.
Furthermore, the bearing 11 of this embodiment includes a first bearing (left side in FIG. 1) on the free end side that rotatably supports one side of the rotating shaft 13 and is loosely fitted in the housing 10, and a second bearing (right side in FIG. 1) on the fixed end side that rotatably supports the other side of the rotating shaft 13 and is fixed to the housing 10. The second bearing on the fixed end side is fixed so that the outer ring of the second bearing is sandwiched between the bearing plate 22 and the housing 10. This prevents the second bearing on the fixed end side from tilting.

The rotating electric machine 1 includes a cylindrical rotor 14 held (fixed) on a rotating shaft 13 , and a stator 18 disposed opposite the rotor 14 and held in the housing 10 .
The housing 10 is made of aluminum, a casting, or the like, and functions as a motor housing that houses the rotor 14 and the stator 18. The housing 10 also has an inner circumferential surface 10a facing the outer circumferential surface 11a of the bearing 11 on the free end side, and has a bearing retaining portion that receives the bearing 11 on the free end side.

The rotating shaft 13 passes through a shaft hole provided in the center of the rotor core of the rotor 14 in the direction of the rotation axis A, and is located on the rotation axis A of the rotor 14. The rotating shaft 13 is driven to rotate about the rotation axis A together with the rotor 14. The rotating shaft 13 also protrudes in the direction of the rotation axis A to the outside of the housing 10 through an opening 21.
Hereinafter, the direction in which the rotation axis A extends (X direction) will be simply referred to as the axial direction. The circumferential direction about the rotation axis A will be simply referred to as the circumferential direction. The radial direction about the rotation axis A will be simply referred to as the radial direction.

The stator 18 includes a stator core (stator iron core) 15 formed in a cylindrical shape.
Although not shown, a plurality of teeth portions protruding radially inward are provided along the circumferential direction on the inner circumference of the stator core 15, and slots are formed between each of the teeth portions.

Furthermore, the stator core 15 has coils 16 wound around each of the teeth, each of which is made up of multiple windings (strands). The coils 16 are provided with coil end portions 17 that protrude from the end faces of the stator core 15.

FIG. 6 is a diagram showing a housing structure on the free end side of a rotating electrical machine of a comparative example.
In the rotating electric machine of the comparative example, a rotating shaft 43 is rotatably supported via two bearings 41. The two bearings 41 are composed of a free end bearing that loosely fits the bearing 41 in the housing 40 and a fixed end bearing that fixes the bearing 41 to the housing 40. The arrangement of the housing 40 and the rotating shaft 43 is similar to that of the housing 10 and the rotating shaft 13 of this embodiment.

The housing 40 has an inner circumferential surface 40a facing the outer circumferential surface 41a of the bearing 41 on the free end side, and has a bearing holding portion that receives the bearing 41 on the free end side.
The corner portion (edge) 42 of the outer ring of the bearing 41 includes an outer ring one-end corner portion 42a, which is a corner of one end face in the axial direction (the left side of the bearing 41 in Figure 6), and an outer ring other-end corner portion 42b, which is a corner of the face opposite the outer ring one-end corner portion 42a (the right side of the bearing 41 in Figure 6).

The fit of the outer ring of the bearing 41 on the free end side is a clearance fit with a predetermined gap between it and the inner surface 40a of the bearing retaining portion of the housing 40 which faces the outer peripheral surface 41a of the bearing 41 on the free end side (located in a radially opposing position).
The outer ring of the bearing 41 is fitted with a clearance fit, which improves assembly and removal properties when attaching and detaching the bearing.

Furthermore, a pressure spring 48 is disposed between one axial end face of the free end bearing 41 (the left side of the bearing 41 in FIG. 6) and an end face 40b of the housing 40 that is axially opposed to one axial end face of the free end bearing 41. The pressure spring 48 is disposed so as to be located at one end face of the outer ring of the bearing 41 as shown in FIG. 6.

By disposing the pressure spring 48, one end face of the outer ring of the bearing 41 on the free end side is pressurized with a predetermined force. This improves the runout accuracy of the rotating shaft 43 and suppresses noise and vibration, etc.

Fig. 7 is a diagram showing a state in which the bearing 41 is inclined in the radial direction in a rotating electric machine of a comparative example. A in Fig. 7 shows the rotation axis when the bearing 41 on the free end side is not inclined in the radial direction. A' in Fig. 7 shows an example of the rotation axis when the bearing 41 on the free end side is inclined in the radial direction. Note that when the rotating shaft is inclined in the radial direction, the bearing is inclined in conjunction with it.
When the rotating electric machine is driven, if the above-mentioned specified gap is formed, the bearing 41 on the free end side in which this specified gap is formed may tilt radially by the amount of the specified gap in either radial direction, as shown in Figure 7.

When the bearing 41 on the free end side is tilted radially, the corner 42a on one end of the outer ring of the bearing 41 may come into contact (including point contact) with the inner circumferential surface 40a of the bearing holder of the housing 40, and this contact increases the stress applied to the housing 40 at the contact point.

If the rotating electric machine continues to operate in this state, the bearing 41 rotates with stress concentrated when the outer ring of the bearing 41 on the free end side creeps. As a result, the inner circumferential surface 40a of the bearing holder of the housing 40, where stress is concentrated, is scraped off by the corner 42a on one end of the outer ring of the bearing 41 on the free end side, forming a linear groove on the inner circumferential surface 40a of the housing 40.

Furthermore, if the cutting chips generated at this time get into various parts of the rotating electric machine 1, abnormal noises will be generated when the rotating electric machine 1 is operated, and the ride quality of the vehicle will be deteriorated. Furthermore, the cutting chips may cause rusting of the inside of the housing 40 and the bearings 41, and if such an event occurs, the life of the rotating electric machine may be shortened.

Fig. 2 is a diagram showing a housing structure on the free end side of the rotating electric machine 1 in this embodiment. Fig. 3 is a partially enlarged view of the housing structure on the free end side of the rotating electric machine 1 in this embodiment. Fig. 4 is a cross-sectional perspective view of the periphery of a bearing on the free end side of the rotating electric machine 1 in this embodiment.
In this embodiment, the corner (edge) 12 of the outer ring of the bearing 11 on the free end side includes an outer ring one-end corner 12a, which is a corner of one end face in the axial direction (the left side of the bearing 11 in Figure 2), and an outer ring other-end corner 12b, which is a corner of the face opposite the outer ring one-end corner 12a (the right side of the bearing 11 in Figure 2).

The outer ring of the bearing 11 on the free end side is fitted with a clearance fit, with a specified clearance between it and the inner circumferential surface 10a of the bearing holder of the housing 10, which faces (is located radially opposite) the outer circumferential surface 11a of the bearing 11 on the free end side. The effect of forming the specified clearance is the same as in the comparative example described above.

Furthermore, a pressure spring 19 is disposed between one axial end face of the free end bearing 11 (the left side of the bearing 11 in FIG. 2) and the end face 10b of the housing 10, which is located axially opposite the one axial end face of the free end bearing 11. The position and effect of the pressure spring 19 are the same as those of the comparative example described above. The pressure spring 19 in this embodiment is, for example, a disc spring or a compression coil spring.

Fig. 5 is a diagram showing a state in which the bearing 11 on the free end side of the rotating electric machine 1 of this embodiment is tilted in the radial direction. In Fig. 5, A indicates the rotation axis when the bearing 11 on the free end side is not tilted in the radial direction. In Fig. 5, A' indicates the rotation axis when the bearing 11 on the free end side is tilted in the radial direction.
When the rotating electric machine is driven, if the above-mentioned specified gap is formed, there is a possibility that the bearing 11 on the free end side where the specified gap is formed will tilt radially in conjunction with the inclination of the rotating shaft 13 by the amount of the specified gap, as shown in Figure 5.

Conventionally, when the bearing 11 on the free end side tilts radially, the outer ring one end side corner 12a of the bearing 11 comes into contact with the inner peripheral surface 10a of the bearing holder of the housing 10. When this happens, the inner peripheral surface 10a of the bearing holder of the housing 10 at the contact position is scraped off. In contrast, in this embodiment, a notch 20 is formed in the inner peripheral surface 10a of the bearing holder of the housing 10 around the location that receives the outer ring one end side corner 12a of the bearing 11 when the bearing 11 on the free end side tilts radially.

By forming the cutout portion 20, even if the bearing 11 on the free end side is tilted radially by the amount of the specified gap described above, the area 20d in the cutout portion 20 receives the outer ring one end corner portion 12a of the bearing 11. This prevents the outer ring one end corner portion 12a of the bearing 11 from contacting the inner circumferential surface 10a of the bearing holder of the housing 10.

As shown in FIG. 4, the cutout portion 20 is formed in an annular shape to have a concave recess along the circumferential direction on the inner circumferential surface 10a of the bearing holder of the housing 10. By forming the cutout portion 20 in an annular shape, the area 20d of the cutout portion 20 can receive the outer ring one end side corner portion 12a of the bearing 11 even if the bearing 11 on the free end side is tilted in any radial direction. This makes it possible to prevent the outer ring one end side corner portion 12a of the bearing 11 on the free end side from coming into contact with the inner circumferential surface 10a of the bearing holder of the housing 10.

The cutout portion 20 is composed of a one-end slope portion (left side in FIG. 3) 20a formed on one axial side of the housing 10, an other-end slope portion (right side in FIG. 3) 20b formed opposite the one-end slope portion 20a, and a central portion 20c formed between the one-end slope portion 20a and the other-end slope portion 20b.

By forming the one end slope portion 20a which is formed so as to be gradually recessed on one side of the outer periphery in the radial direction and the other end slope portion 20b which is formed so as to be gradually recessed on the other side of the outer periphery in the radial direction, stress can be released more easily than with a simple concave shape formed at right angles. As a result, even if the rotating electric machine 1 is used for many years, cracks, breaks, etc. originating from the notch portion 20 can be suppressed.
The radial inclination of the free end bearing 11 varies depending on the distance between the outer peripheral surface 11a of the free end bearing 11 and the inner peripheral surface 10a of the bearing holder, i.e., the size of the predetermined gap. Therefore, the size and the formation position of the cutout portion 20 are set depending on the size of the predetermined gap.

Furthermore, each corner of the cutout portion 20 is chamfered with a rounded edge. By rounding each corner, it is possible to prevent the outer ring one-end corner 12a from coming into contact with any of the corners when the rotating shaft 13 is tilted in any direction in the radial direction, for example. Furthermore, by rounding each corner, it is possible to prevent stress generated by any factor from concentrating on the corners, and it is possible to prevent cracks and breaks originating from the corners of the cutout portion 20 even after many years of use of the rotating electric machine 1.

As described above, in this embodiment, a notch 20 is formed on the inner circumferential surface 10a of the bearing holder of the housing 10 that receives the outer ring one end corner 12a of the free end bearing 11 when the free end bearing 11 is tilted radially. This prevents the outer ring one end corner 12a of the free end bearing 11 from coming into contact with the inner circumferential surface 10a of the bearing holder of the housing 10, providing a rotating electric machine with a housing structure that can prevent damage to the housing 10. Furthermore, the generation of cutting debris can be prevented, providing a rotating electric machine with a housing structure that can be adapted to vehicles and the like that have long life requirements.

The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.

For example, when the bearing 11 on the free end side tilts radially, depending on the size of the specified gap described above and the shape of the inner surface 10a of the bearing holding portion of the housing 10, both the corner 12a on one end side of the outer ring and the corner 12b on the other end side of the outer ring of the bearing 11 on the free end side may come into contact with the inner surface 10a of the bearing holding portion of the housing 10.
In this case, in addition to the cutout portion 20 in this embodiment, a second cutout portion may be formed in the inner peripheral surface 10a of the bearing holder of the housing 10 with which the outer ring other end corner portion 12b of the bearing 11 on the free end side comes into contact. The configuration of the second cutout portion may be the same as that of the cutout portion 20 in this embodiment.

Furthermore, the shape of the cutout portion 20 is not limited to the above-mentioned shape, and it may be formed in a semicircular or polygonal shape.
Furthermore, the rotating electric machine 1 of this embodiment may be configured to use, for example, a single-phase, two-phase AC, three-phase AC, or five-phase AC.

In addition, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

Reference Signs List 1: rotating electric machine, 11: bearing, 11a: outer peripheral surface of bearing, 11b: inner peripheral surface of bearing, 12a: corner portion on one end side of outer ring, 12b: corner portion on the other end side of outer ring, 19: pressure spring, 20: notch portion, 20a: inclined surface portion on one end, 20b: inclined surface portion on the other end, 20c: central portion, 20d: region

Claims (7)

a housing that houses the rotor and the stator and through which the rotating shaft is inserted;
a first bearing that rotatably supports one side of the rotating shaft and is loosely fitted in the housing;
the housing has an inner circumferential surface facing an outer circumferential surface of the first bearing and has a bearing retaining portion that receives the first bearing,
A housing structure for a rotating electric machine, wherein the inner surface of the bearing retaining portion is cut out along a circumferential direction to form a cutout portion that receives an outer peripheral corner portion of the first bearing when the rotating shaft is tilted radially. The housing structure for a rotating electrical machine according to claim 1 , wherein the cutout portion is formed in a concave shape. 3. The housing structure for a rotating electric machine according to claim 1, wherein a plurality of corners of the cutout portion are chamfered. 4. The housing structure for a rotating electric machine according to claim 1, wherein a predetermined gap is formed between the outer circumferential surface of the first bearing and the inner circumferential surface of the housing. 5. A housing structure for a rotating electric machine according to claim 1, wherein a pressure spring is disposed between one end face of the first bearing in the axial direction of the rotating shaft and an end face of the housing facing the one end face of the first bearing. The housing structure for a rotating electric machine according to claim 1 , further comprising a second bearing fixed to the housing and supporting the other side of the rotating shaft so as to be freely rotatable. A housing structure for a rotating electric machine according to any one of claims 1 to 6,
a rotor and a stator housed in the housing;
A rotating shaft that is inserted through the housing;
A rotating electric machine comprising:

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