Rotary electric machine

Abstract

This rotary electric machine comprises an annular outer housing, an inner housing that is disposed radially inward of the outer housing, and an annular stator that is disposed radially inward of the inner housing. The outer housing and the inner housing are secured by a first securing part and a second securing part that are respectively provided on one side and the other side in the axial direction. The stator is secured to the inner housing by a stator-securing part that is provided between the first securing part and the second securing part radially inward of the inner housing. A rigidity reduction part is formed in the inner housing between the stator-securing part and at least one of the first securing part and the second securing part. The rigidity of the rigidity reduction part is lower than the rigidity of the first securing part, the second securing part, and the stator-securing part of the inner housing.

Description

Rotating electric machines

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

[0002] Conventionally, reducing noise generated during operation of rotating electrical machines has been an issue. One of the noise sources in rotating electrical machines is the circular vibration of the stator caused by electromagnetic excitation forces generated between the stator and rotor. In particular, it is known that the circular zero-order vibration, which occurs when the stator repeatedly expands and contracts radially, propagates to the housing, increasing the radiated sound from the rotating electrical machine and generating loud noise.

[0003] Generally, methods for reducing noise from rotating electrical machines involve reducing the stator's circular zero-order vibration by reducing electromagnetic excitation forces or increasing the rigidity of the housing. However, reducing electromagnetic excitation forces must be considered in conjunction with the main performance of the rotating electrical machine, and increasing the rigidity of the housing leads to an increase in weight, so these measures have their limits. Therefore, other measures are necessary to reduce the noise from rotating electrical machines.

[0004] Furthermore, a rotating electric machine having a double housing structure is also known, as shown in Patent Document 1. The rotating electric machine disclosed in Patent Document 1 has a structure in which a stator is fixed to the inner periphery of an inner housing, and both axial ends of the inner housing are fixed to an outer housing. A cooling flow path is formed between the inner housing and the outer housing.

[0005] Japanese Patent Application Publication No. 2019-134567

[0006] In a rotating electric machine with a double housing structure such as that described in Patent Document 1, vibrations occur due to the annular mode of the stator, causing the inner housing to periodically deform in the flow path direction. This vibration propagates from the fixed portions at both ends of the inner housing to the outer housing, increasing the noise of the rotating electric machine. Therefore, suppressing the propagation of vibrations generated in the stator core to the outside is one effective method for reducing noise in a rotating electric machine with a double housing structure.

[0007] In view of the above circumstances, an object of the present invention is to provide a technique capable of reducing noise more than ever before in a rotating electrical machine having a double housing structure with an inner housing and an outer housing.

[0008] A rotating electric machine according to the present invention comprises an annular outer housing, an inner housing arranged radially inside the outer housing, and an annular stator arranged radially inside the inner housing, wherein the outer housing and the inner housing are fixed by a first fixing portion and a second fixing portion provided on one axial side and the other axial side, respectively, and the stator is fixed to the inner housing by a stator fixing portion provided between the first fixing portion and the second fixing portion on the radial inside of the inner housing, and a rigidity reduction portion is formed in the inner housing between the stator fixing portion and at least one of the first fixing portion and the second fixing portion, and the rigidity of the rigidity reduction portion is lower than the rigidity of the first fixing portion, the second fixing portion and the stator fixing portion of the inner housing.

[0009] According to the present invention, it is possible to provide a technique capable of reducing noise more than ever before in a rotating electrical machine having a double housing structure with an inner housing and an outer housing.

[0010] FIG. 10 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a comparative example; FIG. 11 is a diagram showing deformation behavior of an inner housing; FIG. 12 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a first embodiment of the present invention; FIG. 13 is a diagram explaining a mechanism of vibration suppression in the present invention; FIG. 14 is a diagram showing an example of the magnitude of radiated sound from a rotating electric machine; FIG. 15 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a second embodiment of the present invention; FIG. 16 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a third embodiment of the present invention; FIG. 17 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a fourth embodiment of the present invention; FIG. 18 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a fifth embodiment of the present invention; FIG. 19 is a diagram showing deformation behavior of an inner housing in a rotating electric machine in which a wall portion is not provided; FIG. 20 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a sixth embodiment of the present invention; FIG. 21 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a seventh embodiment of the present invention.

[0011] Hereinafter, an embodiment 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 some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0012] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0013] 1 is a schematic cross-sectional view showing an example of the structure of a conventional rotating electric machine as a comparative example to the present invention. As shown in Fig. 1, a rotating electric machine 100Z according to the comparative example includes a rotor 1, a stator 2, an inner housing 3, and an outer housing 4. The outer housing 4 and the inner housing 3 are made of a light metal such as an aluminum alloy or a magnesium alloy, cast iron, or a stainless steel alloy.

[0014] A stator 2 is disposed on the outside of the rotor 1. The stator 2 is fixed to an inner housing 3 disposed on the outer periphery thereof by shrink fitting, press fitting, adhesive, or the like. Hereinafter, the fixed portion between the stator 2 and the inner housing 3 will be referred to as the stator fixing portion. Furthermore, both ends of the inner housing 3 are fixed to the outer housing 4 by shrink fitting, press fitting, adhesive, bolts, or the like. As a result, a space is formed between the inner housing 3 and the outer housing 4, where they are not in contact with each other. This space is used as a flow path 5 for cooling the rotating electric machine 100Z. In other words, the rotating electric machine 100Z is cooled by flowing a coolant such as water through the cooling flow path 5 formed in the portion sandwiched between the outer housing 4 and the inner housing 3.

[0015] When the rotating electric machine 100Z is in operation, an electromagnetic excitation force is generated in the gap between the rotor 1 and the stator 2. This electromagnetic excitation force causes circular vibration in the radial direction of the stator 2. The vibration of the stator 2 is propagated via the inner housing 3 to which the stator 2 is fixed to the fixing portions with the outer housing 4 provided at both ends in the axial direction, and is then transmitted to the outer housing 4. As a result, noise is radiated from the rotating electric machine 100Z to the surrounding area.

[0016] The present invention reduces noise from a rotating electric machine by employing a structure that can suppress propagation of vibrations caused by the annular mode of the stator 2 from the inner housing 3 to the outer housing 4. Note that the specific structure of a rotating electric machine according to the present invention will be described in detail in the following embodiments.

[0017] Fig. 2 is a diagram showing deformation behavior of the inner housing 3 caused by circular vibration of the stator 2 in a rotating electric machine 100Z according to a comparative example. Fig. 2 shows the stator fixing portion to which the stator 2 is fixed and its surroundings of the inner housing 3 shown in Fig. 1. In Fig. 2, the dashed line indicates the shape of the inner housing 3 before deformation, and the solid line indicates the shape of the inner housing 3 after deformation.

[0018] As described above, the outer periphery of the stator 2 is fixed to the inner periphery of the inner housing 3 at a stator fixing portion. Therefore, when the stator 2 expands radially due to electromagnetic excitation force during operation of the rotating electric machine 100Z, the inner housing 3 also deforms radially. At this time, because both ends of the inner housing 3 are fixed to the outer housing 4, deformation occurs in the inner housing 3 between these fixing portions. This deformation of the inner housing 3 propagates from the fixing portions at both ends of the inner housing 3 to the outer housing 4, becoming a source of vibration and noise in the rotating electric machine 100Z.

[0019] Each embodiment of the present invention will be described below, focusing on the differences in structure from the comparative example.

[0020] 3 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a first embodiment of the present invention. Similar to the rotating electric machine 100Z described in the comparative example, the rotating electric machine 100 of this embodiment includes a rotor 1, a stator 2, an inner housing 3, and an outer housing 4.

[0021] The outer housing 4 and the inner housing 3 are fixed to each other by a first fixing portion 6 on one side in the axial direction and a second fixing portion 7 on the other side, and a cooling flow passage 5 is formed between them. The inner housing 3 and the outer housing 4 are made of metal and are manufactured by, for example, casting, die casting, forging, machining, or the like.

[0022] The inner housing 3 has a cylindrical portion (hereinafter referred to as the "cylindrical portion") extending in the axial direction, and a flange-shaped portion (hereinafter referred to as the "flange portion") that protrudes annularly radially outward from an end portion (hereinafter referred to as the "cylindrical end portion") provided on one side of the cylindrical portion. The first fixing portion 6 is a portion where the flange portion of the inner housing 3 and a portion of the outer housing 4 facing it are fixed to each other. The second fixing portion 7 is a portion where the cylindrical portion of the inner housing 3 and a portion of the outer housing 4 facing it are fixed to each other.

[0023] A first sealing portion 9 and a second sealing portion 10 are provided between the first fixing portion 6 and the flow path 5 at the flange of the inner housing 3, and between the second fixing portion 7 and the flow path 5 at the cylindrical portion of the inner housing 3, respectively. The first sealing portion 9 is formed by disposing a seal member in an annular groove provided on the surface of the flange of the inner housing 3 that contacts the outer housing 4. The second sealing portion 10 is formed by disposing a seal member in an annular groove provided on the outer periphery (radially outward) of the surface of the cylindrical portion of the inner housing 3 that contacts the outer housing 4. The first sealing portion 9 and the second sealing portion 10 seal the gap between the outer housing 4 and the inner housing 3, preventing coolant from leaking from the flow path 5 through this gap.

[0024] 3, the first sealing portion 9 and the second sealing portion 10 are provided on the inner housing 3, but one or both of these sealing portions may be provided on the outer housing 4. In this case, the first sealing portion 9 is formed by providing an annular groove on the surface of the outer housing 4 that contacts the flange of the inner housing 3 and disposing a seal member in this groove. The second sealing portion 10 is also formed by providing an annular groove on the inner circumferential side (radially inner side) of the outer housing 4 that contacts the cylindrical portion of the inner housing 3 and disposing a seal member in this groove. That is, the first sealing portion 9 and the second sealing portion 10 can be formed by providing annular grooves on the radially outer side of the inner housing 3 or the radially inner side of the outer housing 4 at both axial ends of the inner housing 3 or the outer housing 4, respectively, and disposing a seal member in these grooves.

[0025] As in the comparative example, the stator 2 is fixed to the stator fixing portion 8 provided between the first sealing portion 9 and the second sealing portion 10 on the radial inside of the inner housing 3 by shrink fitting, press fitting, adhesive, etc.

[0026] In the rotating electric machine 100 of this embodiment, unlike the rotating electric machine 100Z of the comparative example, a part of the inner housing 3 serves as a rigidity-reducing portion 11 that has lower rigidity than other parts and is therefore more susceptible to deformation. Specifically, the thickness of the inner housing 3 is partially thinned between the stator fixing portion 8 and the second fixing portion 7, thereby forming this part as the rigidity-reducing portion 11. In this embodiment, as shown in FIG. 3 , the rigidity-reducing portion 11 is formed by partially recessing the outer circumferential side (radial outer side) of the inner housing 3.

[0027] The inner housing 3 included in the rotating electric machine 100 of this embodiment is provided with the above-described rigidity reducing portion 11, which makes it easier for deformation to occur in the rigidity reducing portion 11. Therefore, when the circular vibration of the stator 2 caused by the electromagnetic excitation force generated during operation of the rotating electric machine 100 is propagated to the inner housing 3 via the stator fixing portion 8, deformation occurs in the inner housing 3 with the rigidity reducing portion 11 acting as a fulcrum. This suppresses vibration propagating from the inner housing 3 to the outer housing 4.

[0028] The vibration suppression mechanism of the present invention will be described below with reference to Fig. 4. Fig. 4 shows the deformation of the inner housing 3 when the stator 2 is vibrating circularly, in the section including the stator fixing portion 8 and the rigidity reducing portion 11 in the schematic cross-sectional view of the rotating electric machine 100 shown in Fig. 3. In Fig. 4, the dashed line indicates the shape of the inner housing 3 before deformation occurs.

[0029] As shown in Fig. 3 , when a load due to the circular vibration of the stator 2 acts on the inner housing 3, a deformation force is generated on the other axial side of the inner housing 3, with the second fixed portion 7 fixed to the outer housing 4 as a fulcrum. In the rotating electric machine 100 of this embodiment, as described above, the rigidity reduced portion 11 is provided between the stator fixed portion 8, which is the load application point of the inner housing 3, and the second fixed portion 7. Therefore, the force that deforms the inner housing 3 in the radial direction due to the circular vibration of the stator 2 is concentrated on the rigidity reduced portion 11, which has lower rigidity than other portions of the inner housing 3, and the deformation at this rigidity reduced portion 11 is larger than at other portions. As a result, the inner housing 3 undergoes deformation, for example, as shown in Fig. 4 , with the rigidity reduced portion 11 as a fulcrum.

[0030] As described above, in the rotating electric machine 100 of this embodiment, by providing the rigidity reduction portion 11 in the inner housing 3, the circular vibration of the stator 2 is converted into deformation behavior of the inner housing 3 with the rigidity reduction portion 11 as a fulcrum. At this time, deformation of the inner housing 3 is reduced on the second fixed portion 7 side relative to the rigidity reduction portion 11. As a result, it is possible to suppress vibrations propagating from the inner housing 3 to the outer housing 4 and reduce noise emitted from the rotating electric machine 100.

[0031] During circular vibration of the stator 2, the load from the stator 2 to the inner housing 3 acts uniformly on the stator fixing portion 8. Therefore, if the rigidity reducing portion 11 is provided within the area of ​​the stator fixing portion 8, the effect of the rigidity reducing portion 11 on the deformation of the inner housing 3 becomes small, and the noise reduction effect described above cannot be sufficiently obtained. For this reason, it is preferable to provide the rigidity reducing portion 11 in the inner housing 3 between the stator fixing portion 8 and the second fixing portion 7.

[0032] As described above, the rotating electric machine 100 has a flow path 5 between the inner housing 3 and the outer housing 4, and a seal member is disposed in the annular groove formed in the first sealing portion 9 and the second sealing portion 10 to prevent leakage of coolant from the flow path 5. Forming a groove for the seal member in the inner housing 3 in this manner may result in the groove having lower rigidity than other parts, such as the stator fixing portion 8, the first fixing portion 6, and the second fixing portion 7. However, if deformation occurs in the groove for the seal member as shown in FIG. 4 , the sealing performance of the first sealing portion 9 and the second sealing portion 10 will be reduced, potentially resulting in leakage of coolant. Therefore, it is desirable that the rigidity reducing portion 11 in the inner housing 3 be formed separately from the groove for the seal member and have lower rigidity than the groove for the seal member.

[0033] It is believed that the larger the dimensions of the rigidity reduction portion 11, the greater the deformation of the inner housing 3, and the greater the effect of reducing noise emitted from the rotating electric machine 100. However, because loads are repeatedly applied to the rigidity reduction portion 11 during operation of the rotating electric machine 100, if the dimensions of the rigidity reduction portion 11 are made too large, the strength of the rigidity reduction portion 11 will be insufficient, and the deformation may not return to normal even when operation of the rotating electric machine 100 is stopped, or in the worst case, the inner housing 3 may break at the rigidity reduction portion 11. Therefore, the dimensions of the rigidity reduction portion 11 need to be determined so as to ensure the strength required for the rigidity reduction portion 11, taking into consideration the material of the inner housing 3 and the magnitude of the excitation force that the inner housing 3 receives from the stator 2, etc.

[0034] 5 is a diagram showing an example of the magnitude of radiated sound from the rotating electric machines 100Z, 100 according to the comparative example and the present embodiment. In FIG. 5 , graphs 51 and 52 show the results of vibration response analysis of the magnitude of radiated sound at the frequency of the annular zero-order mode of the stator 2. Graph 51, shown by a solid line, represents the magnitude of radiated sound in the comparative example in which the inner housing 3 does not have a rigidity reduction section 11. On the other hand, graph 52, shown by a dashed line, represents the magnitude of radiated sound in the first embodiment in which the inner housing 3 has a rigidity reduction section 11. In these graphs 51 and 52, the horizontal axis represents the frequency of the annular zero-order mode of the stator 2, and the vertical axis represents the normalized value of the intensity of the radiated sound.

[0035] 5, the values ​​on the vertical axis of graph 52 are generally about 9% smaller than those of graph 51. Therefore, it can be seen that by applying the structure of this embodiment in which the rigidity reducing portion 11 is provided in the inner housing 3, the sound radiated from the rotating electric machine 100 can be reduced by about 9% compared to the conventional structure.

[0036] According to the first embodiment of the present invention described above, the following advantageous effects are achieved.

[0037] (1) The rotating electric machine 100 includes an annular outer housing 4, an inner housing 3 disposed radially inside the outer housing 4, and an annular stator 2 disposed radially inside the inner housing 3. The outer housing 4 and the inner housing 3 are fixed to each other by a first fixing portion 6 and a second fixing portion 7 provided on one axial side and the other axial side, respectively. The stator 2 is fixed to the inner housing 3 by a stator fixing portion 8 provided between the first fixing portion 6 and the second fixing portion 7, on the radial inside of the inner housing 3. The inner housing 3 includes a rigidity reducing portion 11 formed between the stator fixing portion 8 and the second fixing portion 7, and the rigidity of the rigidity reducing portion 11 is lower than the rigidity of the first fixing portion 6, the second fixing portion 7, and the stator fixing portion 8 of the inner housing 3. As a result, the rotating electric machine 100 having a double housing structure including the inner housing 3 and the outer housing 4 can reduce noise more than a conventional rotating electric machine 100Z.

[0038] (2) An annular groove is provided on the radially outer side of the inner housing 3 or the radially inner side of the outer housing 4, between the second fixing portion 7 and the rigidity reducing portion 11, and a seal member is disposed in this groove to form a second sealing portion 10. The inner housing 3 also has a cylindrical portion extending in the axial direction and a flange portion that protrudes annularly radially outward from a cylindrical end portion provided on one side of the cylindrical portion. The first fixing portion 6 is provided on a surface (first surface) of the flange portion that contacts the outer housing 4. A seal member is disposed between the cylindrical end portion and the first fixing portion 6 on this first surface to form a first sealing portion 9. This configuration prevents coolant from leaking from the cooling flow path 5 formed between the outer housing 4 and the inner housing 3 through a gap between the outer housing 4 and the inner housing 3.

[0039] Second Embodiment Fig. 6 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a second embodiment of the present invention. A rotating electric machine 100A of this embodiment differs from the rotating electric machine 100 of Fig. 3 described in the first embodiment in that a rigidity reducing portion 11 is formed by partially recessing the inner circumferential side (radially inward) of the inner housing 3.

[0040] The vibration reduction mechanism described in the first embodiment absorbs vibrations transmitted from the stator fixing portion 8 to the second fixing portion 7 by increasing the amount of deformation of the rigidity reduction portion 11 relative to the load acting on the stator fixing portion 8. Therefore, if the rigidity of the rigidity reduction portion 11 is similar to that of the first embodiment, even if the rigidity reduction portion 11 is provided on the inner peripheral side of the inner housing 3 as in this embodiment, a vibration reduction effect similar to that of the first embodiment can be obtained. Note that whether the rigidity reduction portion 11 is to be disposed on the outer peripheral side or the inner peripheral side of the inner housing 3 may be determined taking into consideration the availability of installation space and ease of processing depending on the structure of the inner housing 3, etc.

[0041] According to the second embodiment of the present invention described above, the same effects as those of the first embodiment are achieved.

[0042] 7 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a third embodiment of the present invention. A rotating electric machine 100B of this embodiment differs from the rotating electric machine 100 of the first embodiment shown in FIG. 3 in that rigidity reducing portions 11 are formed on both the first fixed portion 6 side and the second fixed portion 7 side of the inner housing 3.

[0043] As described above, in this embodiment, the inner housing 3 has rigidity reducing portions 11 formed between the stator fixing portion 8 and the first fixing portion 6, and between the stator fixing portion 8 and the second fixing portion 7. This increases the amount of deformation of the inner housing 3 when the stator 2 vibrates circularly, thereby achieving a further noise reduction effect.

[0044] In this embodiment, as shown in Figure 7, an example is shown in which the rigidity reduction portions 11 are formed on the outer periphery (radially outer side) of the inner housing 3 on both the first fixed portion 6 side and the second fixed portion 7 side, but as in the second embodiment, one or both of these rigidity reduction portions 11 may be formed on the inner periphery (radially inner side) of the inner housing 3.

[0045] (Fourth embodiment) Fig. 8 is a cross-sectional schematic view showing an example of the structure of a rotating electric machine according to a fourth embodiment of the present invention. A rotating electric machine 100C of this embodiment differs from the rotating electric machine 100A of Fig. 6 described in the second embodiment in that the rigidity reducing portion 11 is not formed on the second fixed portion 7 side of the inner housing 3, but is formed only on the first fixed portion 6 side. Even in this case, the same effects as those of the first and second embodiments can be obtained.

[0046] In this embodiment, as shown in Figure 8, an example is shown in which the rigidity reduction portion 11 is formed on the inner circumferential side (radially inward) of the inner housing 3 between the first fixing portion 6 and the stator fixing portion 8, but as in the first embodiment, the rigidity reduction portion 11 may also be formed on the outer circumferential side (radially outward) of the inner housing 3.

[0047] Fifth Embodiment Fig. 9 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a fifth embodiment of the present invention. A rotating electric machine 100D of this embodiment differs from the rotating electric machine 100C of Fig. 8 described in the fourth embodiment in that a wall portion 12 that protrudes toward the inner periphery (inward in the radial direction) is formed on a portion of the outer housing 4 that faces the flange portion of the inner housing 3. The tip portion on the inner periphery side of this wall portion 12 contacts the inner housing 3 and functions as a restraining portion that restrains the inner housing 3 from the outside.

[0048] The effect of the wall portion 12 in this embodiment will be described below with reference to Figures 10 and 11. Figure 10 shows the deformation behavior of the inner housing 3 when the stator 2 is undergoing circular vibration in the rotating electric machine 100C of Figure 8, which does not have the wall portion 12. On the other hand, Figure 11 shows the deformation behavior of the inner housing 3 when the stator 2 is undergoing circular vibration in the rotating electric machine 100D of Figure 9, which does have the wall portion 12. In Figures 10 and 11, the dashed lines indicate the shape of the inner housing 3 before deformation occurs.

[0049] When the rigidity reducing portion 11 is provided on the first fixed portion 6 side of the inner housing 3, the radial deformation force that the inner housing 3 receives due to the circular vibration of the stator 2 acts not only on the rigidity reducing portion 11 but also on the cylinder end portion where the flange portion and the cylinder portion are connected. Therefore, when the wall portion 12 is not provided on the outer housing 4 as shown in Figure 10, deformation also occurs at the cylinder end portion of the inner housing 3, and deformation at the rigidity reducing portion 11 becomes insufficient. As a result, the noise reduction effect due to deformation of the inner housing 3 cannot be obtained sufficiently.

[0050] On the other hand, when the wall portion 12 is provided on the outer housing 4 as shown in Figure 11, the wall portion 12 protruding toward the cylindrical end of the inner housing 3 restrains the inner housing 3 from the radially outer side near the cylindrical end. This suppresses deformation of the inner housing 3 in this area. As a result, the inner housing 3 can be sufficiently deformed by the rigidity reducing portion 11, and the noise reduction effect described above can be fully obtained.

[0051] According to the fifth embodiment of the present invention described above, the outer housing 4 is provided on its radially inner side with a wall portion 12 that protrudes toward the cylindrical end of the inner housing 3. As a result, even when the inner housing 3 is provided with a flange portion, the noise reduction effect due to deformation of the inner housing 3 can be sufficiently obtained.

[0052] 12 is a schematic cross-sectional view showing an example of the structure of a rotating electric machine according to a sixth embodiment of the present invention. A rotating electric machine 100E of this embodiment differs from the rotating electric machine 100D of the fifth embodiment shown in FIG. 9 in that the wall portion 12 is provided in the inner housing 3 rather than the outer housing 4.

[0053] 12 , a wall portion 12 is provided on the radially outer side of the inner housing 3, protruding from the cylindrical end of the inner housing 3 toward the outer housing 4. The tip portion on the outer circumferential side of this wall portion 12 contacts the outer housing 4, so similar to the fifth embodiment, the inner housing 3 is constrained from the radially outer side near the cylindrical end. Therefore, even when a flange is provided on the inner housing 3, the noise reduction effect due to deformation of the inner housing 3 can be sufficiently obtained.

[0054] Seventh Embodiment Fig. 13 is a cross-sectional schematic view showing an example of the structure of a rotating electric machine according to a seventh embodiment of the present invention. A rotating electric machine 100F of this embodiment differs from the rotating electric machine 100 of Fig. 3 described in the first embodiment in that the inner housing 3 is divided into two parts in the axial direction. In Fig. 13, one of the two divided inner housings 3 is shown as a first inner housing portion 3A, and the other is shown as a second inner housing portion 3B.

[0055] The connecting portion between the first inner housing portion 3A and the second inner housing portion 3B is thinner than the other portions, and the first inner housing portion 3A and the second inner housing portion 3B are connected by fitting these thinned portions together.

[0056] In this embodiment, the inner housing 3 has such a connecting structure, so that the rigidity of the connecting portion (fitting portion) between the first inner housing portion 3A and the second inner housing portion 3B is lower than that of other portions. In other words, by using this connecting portion as the rigidity reducing portion 11, it is possible to obtain the same noise reduction effect as in each of the above-described embodiments, without partially recessing the inner housing 3.

[0057] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0058] Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the invention.

[0059] DESCRIPTION OF SYMBOLS 1... rotor, 2... stator, 3... inner housing, 4... outer housing, 5... flow path, 6... first fixing portion, 7... second fixing portion, 8... stator fixing portion, 9... first sealing portion, 10... second sealing portion, 11... rigidity reducing portion, 12... wall portion

Claims

1. A rotating electric machine comprising: an annular outer housing; an inner housing arranged radially inside the outer housing; and an annular stator arranged radially inside the inner housing, wherein the outer housing and the inner housing are fixed by a first fixing portion and a second fixing portion provided on one axial side and the other axial side, respectively; the stator is fixed to the inner housing by a stator fixing portion provided between the first fixing portion and the second fixing portion, on the radial inside of the inner housing; a rigidity reducing portion is formed in the inner housing between the stator fixing portion and at least one of the first fixing portion and the second fixing portion, and the rigidity of the rigidity reducing portion is lower than the rigidity of the first fixing portion, the second fixing portion and the stator fixing portion of the inner housing.

2. A rotating electric machine according to claim 1, wherein an annular groove is provided between the second fixed portion and the rigidity reducing portion on the radially outer side of the inner housing or the radially inner side of the outer housing, and a sealing member is disposed in the groove.

3. A rotating electric machine according to claim 1, wherein the rigidity reducing portions are formed in the inner housing between the stator fixing portion and the first fixing portion, and between the stator fixing portion and the second fixing portion.

4. A rotating electric machine as claimed in claim 1, wherein the inner housing has a cylindrical portion extending in the axial direction and a flange portion that protrudes annularly radially outward from a cylindrical end portion provided on one side of the cylindrical portion, the first fixed portion is provided on a first surface that contacts the outer housing at the flange portion, and a sealing member is arranged on the first surface between the cylindrical end portion and the first fixed portion.

5. A rotating electric machine according to claim 1, wherein the inner housing has a cylindrical portion extending in the axial direction and a flange portion projecting annularly radially outward from a cylindrical end portion provided on one side of the cylindrical portion, and a wall portion projecting radially inwardly toward the cylindrical end portion is provided on the radially inner side of the outer housing.

6. A rotating electric machine according to claim 1, wherein the inner housing has a cylindrical portion extending in the axial direction and a flange portion that protrudes annularly radially outward from a cylindrical end portion provided on one side of the cylindrical portion, and a wall portion that protrudes from the cylindrical end portion toward the outer housing is provided radially outward of the inner housing.

7. A rotating electric machine according to claim 1, wherein the inner housing is divided into a plurality of sections in the axial direction, and the rigidity reducing portion is a portion where the plurality of divided inner housing sections fit together.

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