Rotary electric machine

Abstract

To provide a rotary electric machine that reduces radiated noise.SOLUTION: The rotary electric machine includes a stator on which windings are wound, a rotor rotatably disposed on the inner diameter side of the stator, and a cylindrical housing that accommodates the stator and the rotor. The housing is formed with a predetermined spacing in the axial direction from the position where the stator is provided, and has a protrusion protruding radially inward on the inner wall of the housing.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a rotating electrical machine.

Background Art

[0002] For environmental reasons, electric vehicles are required to be downsized and lightweight from the viewpoints of mountability and efficiency, and quietness from the viewpoint of comfort in the drive unit. As a method for quieting, for example, in Patent Document 1, in a motor, a structure having a protrusion protruding in the circumferential direction of the inner housing and a groove provided in the outer housing into which the protrusion fits in the circumferential direction is used to change the direction of the propagating vibration from the radial direction to the circumferential direction, reduce the action of the radial vibration in the outer housing, and reduce the vibration and noise of the outer housing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration described in Patent Document 1, the vibration is changed from the radial direction to the circumferential direction by the fitting portion to reduce the radial vibration, but the circumferential vibration due to torque ripple may increase. Further, when suppressing such circumferential vibration, it is desirable that the fitting portion of the components inside the inner housing is formed in the circumferential direction, but there arises a problem that the radial vibration is likely to propagate.

Means for Solving the Problems

[0005] The rotating electrical machine includes a stator around which windings are wound, a rotor rotatably disposed on the inner diameter side of the stator, and a cylindrical housing that houses the stator and the rotor. The housing is formed at a predetermined interval from the position where the stator is provided in the axial direction, and has a protruding portion that protrudes radially inward on the inner wall of the housing.

Advantages of the Invention

[0006] According to the present invention, a rotating electrical machine capable of reducing radiated noise can be provided.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

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Figure 10

Figure 11

Modes for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and for the sake of clarity of explanation, appropriate omissions and simplifications have been made. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be in a single or plural number.

[0009] In the drawings, the positions, sizes, shapes, ranges, etc. of the respective components shown may not represent the actual positions, sizes, shapes, ranges, etc. in order to facilitate the understanding of the invention. For this reason, the present invention is not necessarily limited to the positions, sizes, shapes, ranges, etc. disclosed in the drawings.

[0010] (One Embodiment and Overall Configuration) (FIG. 1, FIG. 2) The drive unit 1 is used as a drive source for an electric vehicle such as an electric car or a hybrid vehicle, and is mounted on the vehicle. The drive unit 1 includes, for example, an inverter 2 as an electronic device, a motor 3, and a speed reducer 4. The motor 3 and the speed reducer 4 are connected to each other. The speed reducer 4 has a gear case 40, and an output shaft 41 protrudes outside thereof. A drive shaft (not shown) for driving a tire (not shown) is connected to the outer end of the output shaft 41. The speed reducer 4 is a mechanism that converts and transmits the rotational speed and torque related to the driving force, converts the rotational speed and torque of the motor 3, and transmits them to the drive shaft via the output shaft 41.

[0011] The inverter 2 is connected to the motor 3. The inverter 2 has an inverter case 21 and an inverter cover 22. An electric circuit 20 is provided inside the inverter case 21. The inverter 2 converts DC power from a battery or the like (not shown) into AC power and supplies it to the motor 3, and controls the power supply to the motor 3. In the drive unit 1, a driving torque or a braking torque is generated according to the command of the inverter 2.

[0012] The motor 3 has a stator 32, a rotor 33, an inner housing 31, and an outer housing 30. The stator 32 has a winding (not shown) wound thereon, and the rotor 33 is rotatably disposed on the inner diameter side of the stator 32. The stator 32 and the rotor 33 are fixed and accommodated on the inner circumference of the cylindrical inner housing 31, for example, by shrink fitting. The inner housing 31 is fastened and fixed to the outer housing 30 with bolts or the like at the fixing portion 36a, and thus is accommodated inside the outer housing 30. Accordingly, the motor 3 has a configuration including the inner housing 31 that holds the stator 32 and the outer housing 30 that holds the inner housing 31.

[0013] A refrigerant flow path 34 for flowing a refrigerant such as cooling water is provided between the inner housing 31 and the outer housing 30. Further, a sealing material 35 for sealing the refrigerant in the flow path is provided in the refrigerant flow path 34. By doing so, heat dissipation performance is ensured.

[0014] Since the motor 3 vibrates due to the electromagnetic exciting force generated in the gap between the rotor 33 and the stator 32 during driving, it serves as an exciting source of the driving unit 1. Inside the motor 3, the vibration of the stator 32 propagates to the inner housing 31, and then propagates to the outer housing 30 through the fixing portion 36a of the inner housing 31 and the outer housing 30. As a result, radiated noise is generated from the vibration of the outer housing 30.

[0015] Among the vibrations of the stator 32, the annular zero-order vibration, which is a vibration mode in which the stator 32 expands and contracts uniformly in the radial direction, is a vibration that is difficult to suppress with the rigidity of the inner housing 31. Therefore, due to the annular zero-order vibration of the stator 32, the radiated noise of the drive unit 1 increases and tends to be high-frequency. In the outer housing 30 that radiates sound, higher-order vibration modes are excited. Therefore, it is necessary to increase the rigidity of the entire outer housing 30 as a countermeasure. If this is done, even if the countermeasure for radiated noise is realized, the drive unit 1 will have the problem of increasing weight. The drive unit 1 is required to have low noise for improving the comfort of the vehicle, and at the same time, it is required to be lightweight for increasing the cruising range. Therefore, it is necessary to reduce noise while avoiding an increase in weight.

[0016] (FIG. 3, FIG. 4) Based on the problems in the above basic configuration, the present invention realizes reduction of the radiated noise of the drive unit 1 caused by the annular zero-order vibration of the stator 32 while suppressing an increase in the weight of the drive unit 1. Note that FIG. 4(a) is a cross-sectional view of the inner housing seen from the axial direction, and FIG. 4(b) is a cross-sectional view of the inner housing seen from the radial direction.

[0017] The inner housing 31 is formed at a predetermined interval from the position where the stator 32 is provided in the axial direction, and has a protruding portion 31a that protrudes radially inward on the inner wall of the inner housing 31. In FIG. 4(b), the thickness h and the length L protruding from the inner housing 31 of the protruding portion 31a are illustrated.

[0018] (FIG. 5) In the inner housing 31, due to the annular zero-order vibration of the stator 32, a vibration mode 37a that propagates through the stator 32 and vibrates in the axial direction (the vertical direction in the drawing) appears. At this time, while the protruding portion 31a vibrates in the axial direction, the portion of the inner housing 31 that holds the stator 32 vibrates in the radial direction as shown by the vibration 39 in the drawing.

[0019] The protruding portion 31a provided in the inner housing 31 axially away from the position of the stator 32 excites the vibration mode 37a when the annular zero-order vibration of the stator 32 is excited, and further makes the natural frequency of the vibration mode 37a coincide with the natural frequency of the annular zero-order vibration of the stator 32. Thereby, the vibration mode 37a of the protruding portion 31a acts as a dynamic vibration absorber for the annular zero-order vibration of the stator 32, and the annular zero-order vibration of the stator 32 is reduced. By doing so, the radiated noise of the drive unit 1 can be reduced.

[0020] In addition, in order to make the natural frequency of the vibration mode 37a in the protruding portion 31a coincide with the natural frequency of the annular zero-order vibration of the stator 32, the values of the length L and the thickness H of the protruding portion 31a shown in FIG. 4 may be changed respectively to adjust the natural frequency.

[0021] (FIGS. 6 and 7) FIG. 6 is a diagram showing the magnitude of the vibration of the drive unit caused by the annular zero-order vibration of the stator when the natural frequency of the vibration mode of the protruding portion is changed. In FIG. 6, the ratio of the vibration levels of each configuration (1) to (4) is shown on the vertical axis based on the peak vibration level of the conventional structure in which no protruding portion is provided in the inner housing.

[0022] FIG. 7 is a table showing the ratio of the natural frequency of the vibration mode of the protruding portion to the annular zero-order vibration of the stator for the configurations (1) to (4) shown in FIG. 6. In verifying the magnitude of the vibration, the natural frequency of the vibration mode 37a of the protruding portion 31a was changed by changing only the length L without changing the thickness H of the protruding portion 31a.

[0023] According to FIGS. 6 and 7, compared with the vibration level of the conventional structure without the protruding portion 31a, in the case of the vibration level of the protruding portion 31a shown in (2) among the configurations of (1) to (4), the natural frequency of the protruding portion 31a is the same as the natural frequency of the 0th-order annular vibration of the stator (the ratio of natural frequencies is 1.0), and the most significant vibration reduction effect appears. Thus, it can be seen that at a predetermined vibration level, the vibration mode 37a of the protruding portion 31a functions as a dynamic vibration absorber with respect to the 0th-order annular vibration of the stator 32.

[0024] (FIG. 8) The configurations (3) and (4) in FIGS. 6 and 7 show the higher-order vibration modes 37b in the protruding portion 31a, and as shown in FIG. 8, they have the characteristic that the phase becomes opposite across the circumferential half of the inner housing 31. Since the 0th-order annular vibration of the stator 32 is a vibration mode that vibrates uniformly in the radial direction, the higher-order vibration mode 37b with a phase difference, although having a smaller effect compared to the vibration mode 37a (FIG. 5), can suppress the 0th-order annular vibration of the stator 32.

[0025] (FIG. 9) By providing the protruding portion 31a of the inner housing within the ranges shown in the installation ranges 38a and 38b, the vibration mode of the protruding portion 31a is excited for suppressing the 0th-order annular vibration of the stator 32. If the protruding portion 31a is provided at a position axially overlapping with the fixing portion 36a, the vibration of the protruding portion 31a is suppressed by the rigidity of the fixing portion 36a, and the effect as a dynamic vibration absorber for suppressing the 0th-order annular vibration of the stator 32 is reduced.

[0026] The installation ranges 38a and 38b of the protrusion 31a are positions that do not overlap axially with the fixing portion 36a of the inner housing 31 and the outer housing 30, and the holding portion 32a of the stator 32, respectively. As shown in FIG. 9, the installation range 38a of the protrusion 31a is a position axially between the fixing portion 36a that fixes the inner housing 31 to the outer housing 30 and the end of the stator 32. Also, the installation range 38b is a position axially between the other end of the stator 32 and the end of the inner housing 31. Note that the protrusion 31a may be provided only in the installation range 38a, only in the installation range 38b, or in both the installation ranges 38a and 38b.

[0027] (First Modified Example) (FIG. 10) The inner housing 31 is fixed to the outer housing 30 by the fixing portions 36a and 36b at both axial ends. The fixing method is, for example, that the fixing portion 36a is bolt-fixed and the fixing portion 36b is press-fitted. Even with such a configuration, suppression of the annular 0th vibration of the stator 32 due to excitation of the vibration mode of the protrusion 31a can be achieved.

[0028] In FIG. 10, the installation range 38a of the protrusion 31a is a position axially between the fixing portion 36a that fixes the inner housing 31 to the outer housing 30 and the end of the stator 32, and the protrusion 31a is a position that does not overlap axially with the fixing portion 36a. Also, the installation range 38b of the protrusion 31a is a position axially between the other end of the stator 32 and the fixing portion 36b, and the protrusion 31a is a position that does not overlap axially with the fixing portion 36b.

[0029] (Second Modified Example) (FIG. 11) FIG. 11(a) is a cross-sectional view of the inner housing seen from the axial direction, and FIG. 11(b) is a cross-sectional view of the inner housing seen from the radial direction. The protruding portion 31a may be configured such that it is not uniformly formed in the circumferential direction. The protruding portion 31a in FIG. 11 is formed in the circumferential direction, but has a notch portion 31b in a part thereof. Even with such a configuration, by adjusting the natural frequency of the protruding portion 31a to match the natural frequency of the annular zero-order vibration of the stator 32, it can function as a dynamic vibration absorber. Note that the number of divisions in the circumferential direction of the protruding portion 31a may be not only two as shown in FIG. 11, but may be formed by being divided into a plurality of portions.

[0030] Although the configuration of the present invention has been described above, the configuration of the housing is not limited to the double structure of the inner housing 31 and the outer housing 30, and can also be realized by a structure of only one housing, and a structure in which the stator 32 is attached to the inner wall of the housing may be used.

[0031] According to the embodiment of the present invention described above, the following operational effects are achieved.

[0032] (1) A rotating electrical machine including a stator 32 around which a winding is wound, a rotor 33 rotatably disposed on the inner diameter side of the stator 32, and a cylindrical housing that houses the stator 32 and the rotor 33, wherein the housing is formed at a predetermined interval from the position where the stator 32 is provided in the axial direction, and has a protruding portion 31a that protrudes radially inward on the inner wall of the housing. By doing so, a rotating electrical machine that realizes reduction of radiated noise can be provided.

[0033] (2) The housing includes an inner housing 31 that houses the stator 32 and an outer housing 30 that houses the inner housing 31, and a refrigerant flow path 34 through which refrigerant flows is formed between the inner housing 31 and the outer housing 30. By doing so, while realizing reduction of radiated noise, cooling performance is ensured.

[0034] (3) The protrusion 31a is provided between the fixing part 36a (36b) that fixes the inner housing 31 to the outer housing 30 and the end of the stator 32 in the axial direction, and does not overlap with the fixing part 36a (36b) in the axial direction. By doing so, reduction of radiated noise can be achieved.

[0035] Note that the present invention is not limited to the above-described embodiments, and various modifications and combinations with other configurations can be made without departing from the gist thereof. Further, the present invention is not limited to those having all the configurations described in the above embodiments, and also includes those in which a part of the configuration is deleted.

Explanation of Reference Numerals

[0036] 1 Drive device 2 Inverter 3 Motor 4 Reducer 20 Electric circuit 21 Inverter case 22 Inverter cover 30 Outer housing 31 Inner housing 31a Protrusion 31b Notch 32 Stator 32a Stator holding part 33 Rotor 34 Refrigerant flow path 35 Sealing material 36a Fixing part 36b Fixing part 37a Vibration mode of the protrusion 37b Higher-order vibration mode of the protrusion 38a Installation range of the protrusion 38b Installation range of the protrusion 39 Radial vibration of the inner housing 40 Gear case 41 Output shaft

Claims

1. A stator around which a winding is wound, a rotor rotatably disposed on the inner diameter side of the stator, and a cylindrical housing that houses the stator and the rotor. The housing is formed at a predetermined interval from the position where the stator is provided in the axial direction, and has a protruding portion that protrudes radially inward on the inner wall of the housing. An electric rotating machine.

2. The electric rotating machine according to claim 1, wherein the housing includes an inner housing that houses the stator and an outer housing that houses the inner housing, and a refrigerant flow path for flowing a refrigerant is formed between the inner housing and the outer housing. An electric rotating machine.

3. The electric rotating machine according to claim 2, wherein the protruding portion is provided between a fixing portion that fixes the inner housing to the outer housing and an end portion of the stator in the axial direction, and does not overlap with the fixing portion in the axial direction. An electric rotating machine.

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