Rotating electric machine

Abstract

To provide a rotary electric machine capable of suppressing deterioration of a cooling performance.SOLUTION: A rotary electric machine is constructed so as to have a stator and a rotor housed in a housing. The housing comprises: a cylindrical inner housing to which the stator is internally fitted; and a cylindrical outer housing that houses the inner housing. The inner housing has an outer peripheral surface formed with a passage wall that stands on a radial direction outer side, and a space surrounded by the outer peripheral surface, the passage wall adjacent in a shaft direction, and an inner peripheral surface of the outer housing is formed as a cooling water passage. The inner housing includes an outer peripheral shape so that the rigidity of a center part in the shaft direction is higher than that of an end part in the shaft direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rotating electric machine having a stator and a rotor housed in a housing.

Background Art

[0002] In the housing of a rotating electric machine, an inner housing is installed inside a cylindrical outer housing, a spiral wall portion is provided around the inner housing, and a spiral space surrounded by the wall portion and the outer housing is configured as a cooling water passage. Patent Document 1 describes a rotating electric machine configured by press-fitting an inner housing into a cylindrical outer housing and shrink-fitting a stator into the cylindrical inner housing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] In the above-described prior art, a highly rigid stator is shrink-fitted to the inner peripheral surface of the inner housing, so that due to the stress after shrink-fitting the stator, the vicinity of the axial center of the inner housing bulges outward more than the vicinity of both ends. Therefore, the clearance between the passage wall of the inner housing and the inner peripheral surface of the outer housing changes. As a result, there is a problem that cooling water leaks into adjacent flow paths and the cooling efficiency decreases.

[0005] Therefore, an object of the present invention is to provide a rotating electric machine capable of preventing a decrease in cooling efficiency.

[0006] One aspect of the present invention is applied to a rotating electric machine in which a stator and a rotor are housed in a housing. The housing has a stator By shrink fittingThe system comprises a cylindrical inner housing into which the inner housing is fitted, and a cylindrical outer housing that accommodates the inner housing. The inner housing has passage walls formed on its outer circumferential surface that rise radially outward, and the space enclosed by the outer circumferential surface, the axially adjacent passage walls, and the inner circumferential surface of the outer housing is formed as a cooling water passage. The axial distance between adjacent passage walls decreases as you move from the axial ends towards the center.

[0007] According to the present invention, the inner housing is configured to have high rigidity in the axial center, thereby suppressing the stress acting to cause outward bulging near the axial center due to the fitted stator. As a result, the outer diameter of the inner housing can be configured not to change along the axial direction, so that leakage of cooling water from the cooling water passage formed between the inner housing and the outer housing to adjacent passages is suppressed, and a decrease in the cooling efficiency of the rotating electric machine can be prevented. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is an axial cross-sectional view of the rotating electric machine of this embodiment. [Figure 2] Figure 2 is an exploded perspective view of the housing of a rotating electric machine. [Figure 3] Figure 3 is a cross-sectional view of the main part of a rotating electric machine. [Figure 4] Figure 4 is a cross-sectional view of the main part of a modified rotating electric machine. [Figure 5] Figure 5 is a cross-sectional view of the main part of a rotating electric machine of another modified example. [Figure 6] Figure 6 is a cross-sectional view of the main part of another modified rotating electric machine. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the attached drawings.

[0010] Figure 1 is an axial cross-sectional view of the rotating electric machine (motor) 1 according to this embodiment. Figure 2 is an exploded perspective view of the housing 10 of the motor 1.

[0011] As shown in Figure 1, the motor 1 is constructed by housing a stator 20 and a rotor 30 within a housing 10. The housing 10 of the motor 1 has an inner housing 11 and an outer housing 12, with the outer housing 12 being fitted over the inner housing 11. These inner housing 11 and outer housing 12 are formed by casting, for example, using an aluminum alloy as the material.

[0012] The motor 1 of this embodiment is mounted on, for example, an electric vehicle and functions as an electric motor that drives the wheels. Furthermore, the motor 1 also functions as a generator that generates electricity (regenerative braking) by receiving the driving force from the rotation of the wheels. The motor 1 may also be used in devices other than automobiles, such as drive systems for various electrical equipment or industrial machinery.

[0013] The inner housing 11 has a cylindrical shape composed of a cylindrical portion 11a, a tip portion 11b, and a flange portion 11c.

[0014] The cylindrical portion 11a is a cylindrical part that houses the stator 20 on its inner circumferential surface. The tip portion 11b is the insertion end of the cylindrical portion 11a that is inserted into the outer housing 12, and is the part that is press-fitted into the press-fit portion 12f, which is part of the inner circumferential surface of the outer housing 12. The flange portion 11c is a flange-shaped part that extends outward on the end opposite to the insertion end of the cylindrical portion 11a, and is fixed to the outer housing 12 by contacting the outer housing 12 and fastening with bolts 19.

[0015] The outer housing 12 has a cylindrical shape consisting of a cylindrical portion 12a, a bottom portion 12b, and a thickened portion 12c.

[0016] The cylindrical portion 12a is a cylindrical part that houses the inner housing 11 inside. The bottom portion 12b is formed as a surface perpendicular to the axial direction at one end of the cylindrical portion 12a. The bottom portion 12b has a through portion 12d through which the rotation axis (not shown) of the rotor 30 passes, and supports the rotation axis so that it can rotate freely. The thickened portion 12c is formed at the end of the cylindrical portion 12a opposite to the bottom portion 12b, and is thicker than the cylindrical portion 12a. The thickened portion 12c abuts against the flange portion 11c of the inner housing 11 and is fastened with bolts 19, thereby fixing the inner housing 11 in the axial direction.

[0017] The cylindrical portion 12a of the outer housing 12 forms a cooling water passage 11d with the inner housing 11 housed inside it.

[0018] More specifically, as shown in Figure 2, radially erected passage walls 111 are arranged in a spiral line on the outer circumferential surface of the cylindrical portion 11a of the inner housing 11, extending from one end to the other. When viewed in an axial cross-sectional view, as shown in Figure 1, the passage walls 111 are arranged in parallel in the axial direction on the outer circumferential surface of the inner housing 11. The outer circumferential surface of the cylindrical portion 11a between adjacent passage walls 111 is formed as a recess 112. The adjacent passage walls 111 and the recess 112 form a space between them and the inner circumferential surface of the cylindrical portion 12a of the outer housing 12, and this space is configured as a cooling water passage 11d through which cooling water flows.

[0019] The cooling water passage 11d is configured such that cooling water flows spirally around the inner housing 11 from one axial direction to the other.

[0020] As shown in FIG. 2, the outer housing 12 is provided with a cooling water inlet 15a and a cooling water outlet 15b. The cooling water inlet 15a and the cooling water outlet 15b penetrate the inner peripheral surface of the cylindrical portion 12a of the outer housing 12 to communicate with the cooling water passage 11d. Thereby, the cooling water flowing into the cooling water passage 11d from the cooling water inlet 15a flows spirally through the inside of the housing 10 along the cooling water passage 11d, and is discharged from the cooling water inlet 15a to the outside of the housing 10. By flowing the cooling water spirally through the inside of the housing 10 in this way, the stator 20 is cooled.

[0021] As shown in FIG. 1, on the outer peripheral surface of the cylindrical portion 11a of the inner housing 11, a first groove portion 114 for mounting a seal member 114a for sealing between the outer peripheral surface of the inner housing 11 and the inner wall of the outer housing 12 is formed between the passage wall 111 and the tip portion 11b. Similarly, a second groove portion 115 for mounting a seal member 115a is formed between the passage wall 111 and the flange portion 11c. Seal members 114a and 115a made of, for example, O-rings are mounted in these first groove portion 114 and second groove portion 115. These seal members 114a and 115a prevent the cooling water flowing through the cooling water passage 11d from leaking to the inside of the inner housing 11.

[0022] Next, an example of the assembling method of the motor 1 will be described. The motor 1 is assembled by fixing the stator 20 to the inside of the inner housing 11 by so-called shrink fitting and then press-fitting and fixing the inner housing 11 into the outer housing 12.

[0023] The shrink fitting of the stator 20 to the inner housing 11 is specifically performed in the following procedure. First, the inner housing 11 is heated to expand in the radial direction, and then the stator 20 is installed on the inner periphery of the inner housing 11. Thereafter, as the inner housing 11 cools and the inner housing 11 contracts in the radial direction, the stator 20 is closely fixed to the inner diameter of the inner housing 11.

[0024] The stator 20 has a highly rigid structure made of laminated electrical steel sheets, and as the inner housing 11 contracts, the highly rigid stator 20 generates radially outward stress in the inner housing 11.

[0025] At this time, near both ends of the inner housing in the axial direction, this stress causes deformation that extends toward the ends, and the inner housing does not bulge radially outward. On the other hand, near the axial center of the inner housing, there is no room for axial deformation, so the stress causes deformation that bulges radially outward. Conventionally, this type of deformation caused the area near the axial center of the inner housing to bulge, resulting in a problem where the outer periphery of the passage wall of the inner housing became non-uniform in the axial direction.

[0026] If the outer perimeter shape of the passage wall of the inner housing is not uniform, the upright height of the passage wall will also be uneven. As a result, the clearance between the passage wall and the inner surface of the outer housing will not be uniform in the axial direction. Consequently, in the cooling water passage formed by the passage wall and the inner surface of the outer housing, particularly at the axial end, there was a risk that cooling water would flow into the adjacent cooling water passage, reducing cooling efficiency. To prevent this, it is conceivable to machine the outer shape of the inner housing to be uniform, but this would increase the assembly man-hours and create new problems such as increased man-hours for managing contamination by cutting chips.

[0027] Therefore, in this embodiment, the following configuration prevents the outer periphery shape of the inner housing 11 from becoming non-uniform, thereby suppressing a decrease in cooling efficiency.

[0028] Figure 3 is a cross-sectional view of the motor 1 of this embodiment, showing the main part of the inner housing 11. On the outer circumferential surface of the inner housing 11, spirally formed passage walls 111 are formed, standing in parallel in the axial direction.

[0029] In this embodiment, the axial width of the passage wall 111 gradually increases from both ends in the axial direction towards the center of the inner housing 11.

[0030] Specifically, the axial width A of the passage wall 111 near the center of the inner housing 11 is formed to be the largest, while the width B of the passage walls 111 on both sides is formed to be smaller than width A. Furthermore, the width C of the passage wall 111 on the outer side, i.e., near the radial end of the inner housing 11, is formed to be smaller than width B.

[0031] By increasing the width A of the passage wall 111 near the axial center of the inner housing 11, the rigidity of the inner housing 11 near the axial center is increased compared to the area near the axial ends.

[0032] The increased rigidity of the inner housing 11 near its axial center suppresses deformation of the inner housing 11 in the radially outward direction due to stress near its axial center, even after shrink-fitting the stator 20.

[0033] Therefore, by configuring the inner housing 11 in this way, deformation of the inner housing 11 in a direction that causes it to bulge near the axial center due to the stress when the stator 20 is shrink-fitted into the inner housing 11 is suppressed, thus preventing the outer circumference shape of the inner housing 11 from becoming non-uniform in the axial direction.

[0034] As a result, in the cooling water passage 11d formed by the passage wall 111 and the inner circumferential surface of the outer housing 12, it is possible to prevent cooling water from flowing out into adjacent cooling water passages 11d, thereby suppressing a decrease in cooling efficiency.

[0035] Next, a modified example of this embodiment will be described.

[0036] As described above, by configuring the inner housing 11 with an outer diameter that increases rigidity near the axial center, deformation of the inner housing 11 due to stress when the stator 20 is shrink-fitted to the inner housing 11 is prevented.

[0037] In order to configure the inner housing 11 with an outer diameter that increases rigidity near the axial center, various shapes other than the one described in Figure 3 can be considered.

[0038] Figure 4 is a cross-sectional view of a modified motor 1 of this embodiment, showing the main part of the inner housing 11.

[0039] In the modified example shown in Figure 4, the distance between adjacent passage walls 111 gradually decreases as you move from both ends in the axial direction of the inner housing 11 towards the center.

[0040] In other words, the inner housing 11 is formed such that the distance D between adjacent passage walls 111 is smallest near the axial center, and the distance E between adjacent passage walls 111 outside of that area is larger than the distance D.

[0041] By shaping the outer circumference of the inner housing 11 in such a way that the distance D between adjacent passage walls 111 is minimized near the axial center, the rigidity of the inner housing 11 near the axial center is increased compared to the rigidity near the axial ends of the inner housing 11.

[0042] Figure 5 is a cross-sectional view of another modified example of this embodiment of motor 1, showing the main part of the inner housing 11.

[0043] In the modified example shown in Figure 5, the radial thickness of the cylindrical portion 11a of the inner housing 11 gradually increases from both ends in the axial direction towards the center. In other words, the inner diameter of the cylindrical portion 11a of the inner housing 11 is uniform, but the outer circumferential surface of the cylindrical portion 11a other than the passage wall 111 is formed to be radially larger outward in the central part than in the axial ends.

[0044] Specifically, the cylindrical portion 11a near the axial center of the inner housing 11 is formed to have the largest radial thickness F, while the radial thickness G of the outer cylindrical portion 11a is formed to be smaller than thickness F. Furthermore, the radial thickness H of the cylindrical portion further out, i.e., near the radial end of the inner housing 11, is formed to be smaller than thickness G.

[0045] By increasing the radial thickness F of the cylindrical portion 11a near the axial center of the inner housing 11, the rigidity near the axial center is increased compared to the axial end.

[0046] Figure 6 is a cross-sectional view of motor 1 of yet another modified example of this embodiment, showing the main part of the inner housing 11.

[0047] In the modified example shown in Figure 6, ribs 117, which have a lower upright height than the passage walls 111, are formed in a spiral row from one end to the other in the recess 112 between adjacent passage walls 111 of the inner housing 11. The upright height of the ribs 117 gradually increases from both ends in the axial direction towards the center.

[0048] By forming ribs 117 in addition to the passage walls 111 on the outer circumference of the inner housing 11, and by increasing the height of the ribs 117 near the axial center, the rigidity of the inner housing 11 near the axial center is increased compared to the axial end sides.

[0049] As described above, this embodiment is applied to a rotating electric machine (motor) 1 in which a stator 20 and a rotor 30 are housed in a housing 10. The housing 10 comprises a cylindrical inner housing 11 into which the stator 20 is fitted, and a cylindrical outer housing 12 that houses the inner housing 11. The inner housing 11 has passage walls 111 that rise radially outward on its outer circumferential surface, and the space enclosed by the outer circumferential surface, adjacent passage walls 111, and the inner circumferential surface of the outer housing 12 is formed as a cooling water passage 11d, and the inner housing 11 has an outer circumferential shape such that the rigidity of the axial central part is higher than that of the axial ends.

[0050] This configuration ensures that the inner housing 11 has high rigidity in its axial center, thereby suppressing the stress that would otherwise cause the fitted stator 20 to bulge outward near the axial center. As a result, the outer diameter of the inner housing 11 does not change along the axial direction, which prevents cooling water from leaking into adjacent passages in the cooling water passage 11d formed between the inner housing 11 and the outer housing 12, thus preventing a decrease in the cooling efficiency of the motor 1.

[0051] Furthermore, in this embodiment, the width of the passage wall 111 in the axial direction is greater in the central part than at the ends, so the rigidity of the inner housing 11 near the axial central part can be made higher compared to both ends of the inner housing 11 in the axial direction.

[0052] Furthermore, in this embodiment, the passage walls 111 are formed to spirally surround the outer circumferential surface of the inner housing 11, and the axial distance between adjacent passage walls 111 decreases from the ends toward the center.

[0053] This configuration allows the rigidity of the inner housing 11 near its axial center to be higher compared to both ends of the inner housing 11 in the axial direction.

[0054] Furthermore, in this embodiment, the radial thickness of the inner housing 11 increases from the ends towards the center.

[0055] This configuration allows the rigidity of the inner housing 11 near its axial center to be higher compared to both ends of the inner housing 11 in the axial direction.

[0056] Furthermore, in this embodiment, the inner housing 11 has ribs 117 formed between adjacent passage walls 111, with a lower upright height than the passage walls 111, spirally encircling the outer circumference of the inner housing 11. The upright height of the ribs 117 increases from the ends towards the center.

[0057] This configuration also allows the rigidity of the inner housing 11 near its axial center to be higher than that of the inner housing 11 at both ends in the axial direction.

[0058] Although embodiments of the present invention have been described above, the configurations described in the above embodiments and each of the modifications represent only a part of the application examples of the present invention and are not intended to limit the technical scope of the present invention.

[0059] As described above, in this embodiment, the thickness of the passage walls 111 is gradually increased from the axial end of the inner housing 11 toward the center (Figure 3), the distance between the passage walls 111 is gradually decreased (Figure 4), the thickness of the cylindrical portion 11a is gradually increased (Figure 5), or the upright height of the ribs 117 formed between the passage walls 111 is gradually increased (Figure 6). However, the embodiment is not limited to this. A predetermined range near the axial center of the inner housing 11 (for example, only the central part of 1 / 3 of the axial length of the inner housing 11) may be configured to increase the thickness of the passage walls 111 in a step-like manner compared to the ends, decrease the distance between the passage walls 111 in a step-like manner, increase the thickness of the cylindrical portion 11a in a step-like manner, or increase the upright height of the ribs 117 formed between the passage walls 111 in a step-like manner.

[0060] Furthermore, the configurations shown in Figures 3 to 6 described above may be combined. For example, as shown in Figure 3, the thickness of the passage wall 111 may be gradually increased from the axial end of the inner housing 11 towards the center, and as shown in Figure 5, the thickness of the cylindrical portion 11a may be gradually increased.

[0061] Furthermore, in the modified example shown in Figure 6 above, ribs 117 are formed in a spiral row in the recess 112 between adjacent passage walls 111, but the design is not limited to this. Multiple rows of ribs 117 may be formed spirally between adjacent passage walls 111. Alternatively, the ribs 117 may be formed so that their axial width widens near the center, rather than their height. [Explanation of symbols]

[0062] 1: Motor, 10: Housing, 11: Inner housing, 11a: Cylindrical section, 11d: Cooling water passage, 12: Outer housing, 15a: Cooling water inlet, 15b: Cooling water outlet, 20: Stator, 111: Passage wall, 112: Recess, 117: Rib

Claims

1. A rotating electric machine comprising a stator and a rotor housed within a housing, The housing comprises a cylindrical inner housing into which the stator is fitted by shrink-fitting, and a cylindrical outer housing that houses the inner housing. The inner housing has passage walls formed on its outer circumferential surface that rise radially outward, and the space enclosed by the outer circumferential surface, the axially adjacent passage walls, and the inner circumferential surface of the outer housing is formed as a cooling water passage. The axial distance between adjacent passage walls decreases as you move from the axial end towards the center. Rotating electric machine.

2. A rotating electric machine according to claim 1, The width of the passage wall in the axial direction is greater in the central part than at the ends. Rotating electric machine.

3. A rotating electric machine according to claim 1, The passage wall is formed to spirally surround the outer surface of the inner housing. Rotating electric machine.

4. A rotating electric machine according to claim 1, The radial thickness of the inner housing increases from the end portion toward the center portion. Rotating electric machine.

5. A rotating electric machine according to any one of claims 1 to 4, The inner housing is formed such that, between adjacent passage walls, ribs with a lower vertical height than the passage walls are formed to spirally surround the outer circumference of the inner housing. The height of the rib increases from the end towards the center. Rotating electric machine.

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