Bearing structure of a rotating electric machine and a rotating electric machine

Abstract

To provide a bearing structure of a rotary electric machine which can inhibit decrease of a preload of a bearing.SOLUTION: A bearing structure of a rotary electric machine includes: a shaft to which a rotor is fixed; a bearing which rotatably supports the shaft; a housing which has a bearing holding part configured to receive an outer ring of the bearing with its inner peripheral surface and into which the shaft is inserted; and a disc spring which is disposed within the bearing holding part and biases the bearing to one axial side of the shaft. The disc spring is disposed at the other axial side relative to the bearing. An inner peripheral surface of the bearing holding part is formed with an annular groove which is cut out along a circumferential direction and receives an outer periphery of the disc spring compressed to the other axial side.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a bearing structure of a rotating electrical machine and a rotating electrical machine.

Background Art

[0002] Conventionally, in a rotating electrical machine, a shaft inserted through a rotor is supported by two bearings. One bearing fixes the axial position, and the other bearing is a free end without fixing the axial position. In this type of rotating electrical machine, in order to suppress noise and vibration, it is common to arrange a spring between the other bearing and the housing facing the bearing to apply a preload to the other bearing (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In this type of rotating electrical machine, when a load exceeding the preload is applied from the outside, the shaft moves axially, and the preload applied to the bearing is released. When such a release of the preload occurs, play occurs inside the bearing, and the rattling of the bearing increases the noise and vibration of the rotating electrical machine.

[0005] The present invention has been made in view of the above situation, and provides a bearing structure of a rotating electrical machine that can suppress the release of the preload of the bearing.

Means for Solving the Problems

[0006] A bearing structure for a rotating electric machine according to one aspect of the present invention comprises a shaft to which a rotor is fixed, a first bearing that pivotally supports the shaft so as to be rotatable on one axial side, a second bearing that pivotally supports the shaft so as to be rotatable on the other axial side, a housing through which the shaft is inserted and which has a bearing retaining portion that receives the outer ring of the second bearing on its inner circumferential surface, and a disc spring disposed within the bearing retaining portion that biases the second bearing on one axial side of the shaft. The disc spring is disposed on the other axial side of the bearing, and an annular groove is formed on the inner circumferential surface of the bearing retaining portion that extends in the circumferential direction and receives the outer circumference of the disc spring when compressed on the other axial side. The groove is formed at a distance from the other axial end face formed on the bearing retaining portion toward the one axial side. 。

[0007] Furthermore, the groove may be formed on the other axial side of the position on the outer circumference of the disc spring when preload is applied to the second bearing. Furthermore, one axial side of the groove may be an inclined surface connected to the inner circumferential surface of the bearing retaining portion. Furthermore, the other axial side of the shaft may be the load side of the rotating electric machine. Furthermore, another aspect of the present invention provides a rotating electric machine comprising the bearing structure of the rotating electric machine described above, and a stator. [Effects of the Invention]

[0008] According to one aspect of the present invention, a bearing structure for a rotating electric machine that can suppress the release of bearing preload can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] This is a diagram showing an example configuration of the rotating electric machine of this embodiment. [Figure 2] This is an enlarged view showing the bearing retaining portion of the second lid. [Figure 3] This is a view of the bearing retaining portion of the second lid from one side. [Figure 4] This is a schematic diagram showing the condition of the bearings in a rotating electric machine as an example. [Figure 5] This figure shows a modified example of the bearing retaining portion of the second lid. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings. In the embodiments, for the sake of clarity, structures and elements other than the main parts of the present invention will be simplified or omitted in the description. Also, the same elements will be denoted by the same reference numerals in the drawings. Note that the shapes and dimensions of each element shown in the drawings are schematic representations and do not represent the actual shapes and dimensions.

[0011] Figure 1 shows an example of the configuration of the rotating electric machine according to this embodiment. In the following description, the direction parallel to the extension direction of the rotation axis Ax will be referred to as the axial direction, the circumferential direction centered on the rotation axis Ax will be simply referred to as the circumferential direction, and the radial direction centered on the rotation axis Ax will be simply referred to as the radial direction.

[0012] The rotating electric machine 10 shown in Figure 1 is an inner rotor type motor and comprises a rotor 11, a stator 12, a shaft 13, a housing 14, and bearings 15 and 16. In Figure 1, the extension direction (axial direction) of the rotation axis Ax of the rotating electric machine 10 is the left-right direction of the paper. The left side in the figure is also sometimes referred to as one side in the axial direction, and the right side in the figure is sometimes referred to as the other side in the axial direction. The load side of the rotating electric machine 10 is assumed to be the other side.

[0013] The rotor 11 has a cylindrical iron core into which a shaft 13 is fitted along the rotation axis Ax. The shaft 13 is rotatably supported by bearings 15 and 16 located on one and the other axial sides. The rotor 11 may be configured in any of the following ways: for example, a magnet-embedded rotor, a surface-mounted magnet rotor, a squirrel-cage rotor, or a wound-type rotor.

[0014] The stator 12 is arranged concentrically with the outer periphery of the rotor 11 with a slight air gap therebetween. A coil 12a is mounted along the outer periphery of the rotor 11 on the stator 12. In the rotating electric machine 10, by sequentially switching the magnetic field of the stator 12 by controlling the current of the coil 12a, an attractive force or a repulsive force with the magnetic field of the rotor 11 is generated in the stator 12. Thereby, the rotor 11 and the shaft 13 rotate about the rotation axis Ax.

[0015] The housing 14 has a main body portion 14a, a first lid portion 14b, and a second lid portion 14c, and houses the rotor 11 and the stator 12 therein. The main body portion 14a houses the rotor 11 and the stator 12 and has a cylindrical internal space that is open on one side and the other side.

[0016] The first lid portion 14b is attached to one side of the main body portion 14a and closes the opening on one side of the main body portion 14a. One end of the shaft 13 protrudes outside the housing 14 through the first lid portion 14b. Further, on the inner surface of the first lid portion 14b, a bearing holding portion 17 is formed around the hole for receiving the shaft 13. The bearing holding portion 17 is a cylindrical notch that houses the bearing 15 on one side, is open on the other side, and has an annular retaining portion on one side.

[0017] A bearing plate 19 is attached to the other side of the bearing holding portion 17 of the first lid portion 14b. Thereby, the outer ring 15a of the bearing 15 on one side is received by the inner peripheral surface of the bearing holding portion 17 and is positioned in the axial direction while being sandwiched between the bearing holding portion 17 and the bearing plate 19.

[0018] The second lid portion 14c is attached to the other side of the main body portion 14a and closes the opening on the other side of the main body portion 14a. The other end of the shaft 13 protrudes outside the housing 14 through the second lid portion 14c. Further, on the inner surface of the second lid portion 14c, a bearing holding portion 18 is formed around the hole for receiving the shaft 13.

[0019] Figs. 2(a) and 2(b) are enlarged views showing the bearing holding portion 18 of the second lid portion 14c. The bearing holding portion 18 is a cylindrical notch for accommodating the bearing 16 on the other side, with one side being open and having an annular retaining portion 18a on the other side. Also, the outer ring 16a of the bearing 16 is received by the inner peripheral surface 18b of the bearing holding portion 18.

[0020] A disc spring 20 as a preloading spring is inserted into the bearing holding portion 18 of the second lid portion 14c on the other side of the bearing 16 on the other side. The disc spring 20 is sandwiched between the retaining portion 18a of the bearing holding portion 18 and the outer ring 16a of the bearing 16, and is arranged such that the outer peripheral side inclines toward one side.

[0021] The disc spring 20 functions to load a preload to the shaft 13 toward one side via the bearing 16 by biasing the outer ring 16a of the bearing 16 toward one side. Also, when the shaft 13 is pulled in the other side, the disc spring 20 is compressed to the other side by the bearing 16 that moves to the other side together with the shaft 13.

[0022] Also, as shown in Figs. 2 and 3, an annular groove 18c extending in the circumferential direction is formed on the inner peripheral surface 18b of the bearing holding portion 18 in the second lid portion 14c. The axial position of the groove 18c is formed at an interval from the retaining portion 18a, and is located on the compression side (the other side) from the position of the outer peripheral portion of the disc spring 20 in a state where a preload is loaded on the bearing 16. As shown in Fig. 2(b), the groove 18c receives the outer peripheral portion of the disc spring 20 with the groove 18c when the disc spring 20 is compressed to the other side, suppressing excessive compression of the disc spring 20.

[0023] Next, while referring to Fig. 4, the operation when the shaft 13 is pulled in will be described. Fig. 4(a) is a schematic view showing the normal state of the bearings 15 and 16 in the rotating electric machine 10a of the comparative example. Fig. 4(b) is a schematic view showing the state of the bearings 15 and 16 when the shaft 13 is pulled in the other side in the rotating electric machine 10a of the comparative example.

[0024] The comparative example, the rotating electric machine 10a, differs from the rotating electric machine 10 of this embodiment in that a groove 18c is not formed in the bearing holding portion 18 on the other side. For simplicity, the rotor 11 and stator 12 are not shown in Figure 4.

[0025] As shown in Figure 4(a), the shaft 13 of the comparative example rotating electric machine 10a is preloaded on one side by a disc spring 20. As a result, in the bearing 15 on one side, the rolling elements 15c are in point contact with one side of the outer ring 15a and the other side of the inner ring 15b, and are pressed down by the spring load. Similarly, in the bearing 16 on the other side, the rolling elements 16c are in point contact with the other side of the outer ring 16a and one side of the inner ring 16b, and are pressed down by the spring load. Therefore, both bearings 15 and 16 rotate without any play.

[0026] On the other hand, as shown in Figure 4(b), when the shaft 13 is pulled to the other side by a pressure exceeding the preload, the shaft 13 moves to the other side from the state shown in Figure 4(a) together with the inner rings 15b and 16b fixed to the shaft 13. Then, in the bearing 16 on the other side, the load to the other side is transmitted to the outer ring 16a via the rolling elements 16c. As a result, the disc spring 20 is excessively compressed by the outer ring 16a of the bearing 16, resulting in a state of preload release where no preload is applied to the shaft 13 and the bearings 15 and 16.

[0027] In the preload-reduced state shown in Figure 4(b), play occurs inside the bearing 15 on one side, causing the rolling elements 15c to rattle and generate noise and vibration. Furthermore, in the bearing 16 on the other side, the rolling elements 16c wear out more easily than usual because the bearing 16 is subjected to a large load.

[0028] In contrast, in the rotating electric machine 10 of this embodiment, an annular groove 18c is formed on the inner circumferential surface 18b of the bearing holding portion 18. As shown in Figure 2(b), in the rotating electric machine 10 of this embodiment, when the disc spring 20 is compressed to the other side, the outer circumference of the disc spring 20 enters and gets caught in the groove 18c. As a result, the disc spring 20 is prevented from moving to the other side, and the disc spring 20 caught in the groove 18c generates a reaction force to one side against the load from the outer ring 16a of the bearing 16.

[0029] As described above, in the rotating electric machine 10 of this embodiment, the disc spring 20 that catches in the groove 18c restricts the movement of the other side of the outer ring 16a of the bearing 16. This suppresses the release of preload from the shaft 13, and also suppresses noise and vibration caused by rattling of the bearing 15.

[0030] The present invention is not limited to the embodiments described above, and various improvements and design modifications may be made without departing from the spirit of the invention. For example, in the above embodiment, the case where the rotating electric machine 10 is a motor was described, but the rotating electric machine 10 may also be a generator.

[0031] Furthermore, in the bearing retaining portion 18 of the above embodiment, as shown in Figure 5, an annular inclined surface 18d may be formed on one side of the groove 18c, which is connected to the inner circumferential surface 18b of the bearing retaining portion 18. According to the configuration example in Figure 5, when the load on the disc spring 20 in the pulling direction decreases, the disc spring 20 is easily guided by the inclined surface 18d of the groove 18 and returns to its normal position. The inclined surface 18d may be tapered, with the groove becoming shallower on one side, or it may be formed into a curved shape by adding a radius to one side of the groove 18c.

[0032] Furthermore, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0033] 10...Rotating electric machine, 11...Rotor, 12...Stator, 12a...Coil, 13...Shaft, 14...Housing, 14a...Main body, 14b...First cover, 14c...Second cover, 15,16...Bearing, 15a,16a...Outer ring, 15b,16b...Inner ring, 15c,16c...Rolling element, 17,18...Bearing holder, 18a...Retaining part, 18b...Inner circumferential surface, 18c...Groove, 18d...Inclined surface, 19...Bearing plate, 20...Disc spring

Claims

1. The rotor is fixed to the shaft, A first bearing that pivotally supports the shaft so that it can rotate on one side in the axial direction, A second bearing that pivotally supports the aforementioned shaft so that it can rotate on the other side in the axial direction, A housing having a bearing retainer that supports the outer ring of the second bearing on its inner circumference, through which the shaft is inserted, The bearing is provided with a disc spring disposed within the bearing holder and biasing the second bearing on one axial side of the shaft, The disc spring is positioned on the other axial side of the second bearing. An annular groove is formed on the inner circumferential surface of the bearing retaining portion, which extends in the circumferential direction and receives the outer circumference of the disc spring that is compressed in the other axial direction. The groove is formed at a distance from the other axial end face formed in the bearing retaining portion toward one axial side. Bearing structure of a rotating electrical machine.

2. The groove is formed on the other axial side of the position on the outer circumference of the disc spring when preload is applied to the second bearing. The bearing structure for a rotating electric machine according to claim 1.

3. The surface of the groove on one axial side is an inclined surface that connects to the inner circumferential surface of the bearing retaining portion. The bearing structure for a rotating electric machine according to claim 1.

4. The other axial side of the aforementioned shaft is the load side of the rotating electric machine. The bearing structure for a rotating electric machine according to claim 1.

5. A bearing structure for a rotating electric machine according to any one of claims 1 to 4, stator and, A rotating electric machine equipped with the following features.

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