Rotary electric machine
Patent Information
- Application Number
- JP2022106443
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-06-30
- Publication Date
- 2025-02-04
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing rotating electric machines generate significant radiated sound due to annular zero-order vibration, which is challenging to suppress using conventional methods like increasing wall thickness or adding ribs, as these approaches require many parts and increase weight.
A rotating electric machine design featuring a housing with an inner wall, outer wall, and connecting portions that form a refrigerant flow path, where a gap between the stator and inner wall creates a phase difference in vibrations, reducing sound radiation without increasing the number of parts.
The design effectively reduces radiated sound by minimizing the contact area between the stator and housing, achieving a phase difference in vibrations to decrease sound radiation without adding components.
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a rotating electric machine. [Background technology]
[0002] Reducing the radiated noise generated during operation of a rotating electric machine has been an issue for some time. One of the sources of radiated noise from a rotating electric machine is the radial circular vibration of the stator caused by the electromagnetic excitation force generated in the space between the stator and rotor. It is known that the radiated noise is particularly loud due to the circular zero-order vibration, which is a natural vibration mode in which the stator expands in the radial direction.
[0003] Generally, there are two ways to reduce vibration: measures for the excitation force and measures for the transmission system. Measures for the excitation force that target motors involve reducing the electromagnetic excitation force, but there are limitations to what can be done because it is necessary to consider the impact on the main performance of the motor. As for measures for the transmission system, in the case of circular zero-order vibration, it is generally possible to suppress vibration by increasing the housing's rigidity through increased wall thickness or ribs.
[0004] Here, as a method for holding a stator in a housing, for example, there is a method of tightly adhering the outer peripheral surface of the stator to the inner peripheral surface of the housing by shrink fitting. When the stator is held in the housing by shrink fitting, the stator and the housing are in close contact with each other, so the circular zeroth vibration becomes a vibration mode in which the stator and the housing expand in the radial direction as a unit. For this type of vibration mode, measures to suppress vibration by increasing the wall thickness or increasing the rigidity of the housing by using ribs are not very effective, and in order to reach the target performance, many ribs and wall thickness are required, which may require a lot of weight.
[0005] Patent Document 1 discloses an electric compressor including a housing, a rotating shaft accommodated within the housing, a compression section that compresses a fluid as the rotating shaft rotates, an electric motor having a rotor that rotates integrally with the rotating shaft and a stator fixed to the housing and that drives the compression section, and a bearing that rotatably supports the rotating shaft relative to the housing, wherein the housing includes an inner housing that accommodates the electric motor and to which the stator is fixed, a bearing plate that holds the bearing, an outer housing that accommodates the inner housing, and a discharge housing through which fluid compressed by the compression section is discharged and which is fixed to the compression section, wherein the compression section is fixed to the inner housing, the outer housing is fixed to the discharge housing, the inner housing and the bearing plate are fixed by bolts, and the inner surface of the outer housing and the outer surface of the inner housing are spaced apart. [Prior art documents] [Patent documents]
[0006] [Patent Document 1] JP 2019-173658 A Summary of the Invention [Problem to be solved by the invention]
[0007] The invention described in Patent Document 1 requires a large number of parts, which increases the number of assembly steps. [Means for solving the problem]
[0008] A rotating electric machine according to a first aspect of the present invention comprises a rotor, a circular stator facing the rotor at a predetermined distance, and a housing in which the stator is held, the housing comprising an inner wall that holds the radial inner surface of the housing, an outer wall facing the inner wall in the radial direction, and a connecting portion that connects the inner wall and the outer wall, the inner wall, the outer wall and the connecting portion forming a refrigerant flow path through which a refrigerant can flow, the inner wall facing the stator and having a gap between the stator and a surface that overlaps at least a portion of the connecting portion in the radial direction. Effect of the Invention
[0009] According to the present invention, the radiated sound of a rotating electrical machine can be reduced without increasing the number of parts and the cost. [Brief description of the drawings]
[0010] [Figure 1] Cross-sectional view of a rotating electrical machine [Diagram 2] A perspective view of the housing [Diagram 3] A perspective view of a housing in which a stator is shrink-fitted. [Figure 4] Conceptual diagram explaining the structure of the gap [Diagram 5] A diagram showing the relationship between the ratio of the contact area between the inner wall of the housing and the outer circumferential surface of the stator and the volume of radiated sound. [Figure 6] FIG. 1 shows the structure of a stator that forms a gap. [Figure 7] FIG. 1 shows a structure of a housing that forms a gap. [Figure 8] A diagram showing the effect of the ratio of the inner wall thickness to the outer wall thickness of the housing on the volume of radiated sound. [Figure 9] FIG. 13 is a diagram showing a shape of a housing in a first modified example. [Figure 10] Diagram showing variations in gaps DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] --First embodiment-- Hereinafter, a first embodiment of a rotating electric machine will be described with reference to FIGS.
[0012] Fig. 1 is a cross-sectional view of a rotating electric machine 100 according to the present invention. The rotating electric machine 100 includes a stator 1, a rotor 2 disposed inside the stator 1, a shaft 4 that rotates synchronously with the rotor 2, and a cylindrical housing 3 that houses the stator 1, the rotor 2, and the shaft 4. The shaft 4 extends in the left-right direction in the figure, and the housing 3 is cylindrical with the shaft 4 at its center. In this embodiment, the left-right direction in Fig. 1 is called the axial direction J, and the up-down direction in Fig. 1 is called the radial direction R.
[0013] When the rotating electric machine 100 is in operation, an electromagnetic excitation force is generated in the gap between the stator 1 and the rotor 2. This electromagnetic excitation force generates a circular vibration in the radial direction R, which propagates to the housing 3 and becomes radiated sound. Among the circular vibrations of the stator 1, the radiated sound becomes louder due to the circular zero-order vibration, which is a natural vibration mode in which the stator 1 expands in the radial direction R with respect to the shape before deformation. Below, a detailed configuration of the rotating electric machine 100, in particular a configuration for reducing the radiated sound of the rotating electric machine 100 due to the reduction of the circular zero-order vibration of the stator 1, will be described.
[0014] A predetermined gap exists between the stator 1, which is a non-rotating body, and the rotor 2, which is a rotating body, so as not to impede rotation, and as described below, a gap also exists between the stator 1 and the housing 3 in order to solve the problems of the present invention. Below, the latter gap between the stator 1 and the housing 3, i.e., the air gap, will be described in detail. The former gap between the stator 1 and the rotor 2 will not be described in particular. To distinguish between the two, the gap between the stator 1 and the housing 3 will be called the "air gap," and the gap between the stator 1 and the rotor 2 will be called the "predetermined separation distance."
[0015] Fig. 2 is a perspective view of the housing 3. The viewpoint of Fig. 2 is changed by approximately 90 degrees from Fig. 1, and the vertical direction in the figure is the axial direction J. In Fig. 2, the direction that passes through the central axis of the cylindrical housing 3 and is perpendicular to the axial direction J is the radial direction R. Furthermore, a circumferential direction C is defined in Fig. 2.
[0016] The space inside the housing 3 in which the stator 1 is accommodated is called a stator accommodating portion 30. The housing 3 includes an inner wall 31 that is in close contact with the outer peripheral surface of the stator 1 and holds the stator 1, and an outer wall 32 that faces the inner wall 31 in the radial direction R. Furthermore, the housing 3 is provided with connection portions 33 at predetermined intervals in the circumferential direction C, which connect the inner wall 31 and the outer wall 32 of the housing 3. In the housing 3, a refrigerant flow path 34 is formed by the inner wall 31, the outer wall 32, and the connection portion 33. The refrigerant flow path 34 is formed across the axial direction J of the housing 3, and allows the refrigerant to circulate through an axial end of the housing 3, for example, a gear box or an inverter case.
[0017] FIG. 3 is a perspective view of the housing 3 to which the stator 1 is shrink-fitted. In FIG. 3, the stator 1 is shrink-fitted to the inner periphery of the housing 3 shown in FIG. 2. The outer diameter of the stator 1 is larger than the inner diameter of the inner wall 31 of the housing 3, and by shrink-fitting the stator 1 into the housing 3, the inner wall 31 and the outer periphery of the stator 1 are brought into close contact with each other, so that the stator 1 can be held. At this time, the difference between the outer diameter of the stator 1 and the inner diameter of the inner wall 31 of the housing 3 is the interference in the shrink-fitting. As will be described in detail later, only a part of the inner wall 31 is in close contact with the outer periphery of the stator 1, and the entire surface of the inner wall 31 is not in close contact with the outer periphery of the stator 1.
[0018] Here, a method for holding the stator 1 in the housing 3 by shrink fitting will be described. First, the housing 3 is heated to a predetermined temperature. This causes the housing 3 to thermally expand, and the inner diameter of the stator accommodating portion 30, i.e., the inner wall 31, becomes larger. Next, the stator 1 is inserted into the thermally expanded stator accommodating portion 30 of the housing 3. Finally, the housing 3 is cooled, causing it to contract, and the outer circumferential surface of the stator 1 comes into close contact with the inner wall 31 of the housing 3, so that the stator 1 is held in the housing 3.
[0019] The rotating electric machine 100 includes a retaining portion 51 that retains the stator 1 by bringing the outer peripheral surface of the stator 1 into close contact with the inner wall 31 of the housing 3, and a gap portion 52 where the outer peripheral surface of the stator 1 does not contact the inner wall 31. The gap portion 52 is provided on a surface where the inner wall 31 of the housing 3 overlaps with the connecting portion 33 in the radial direction R, and the retaining portion 51 is provided on a surface where the inner wall 31 of the housing 3 does not overlap with the connecting portion 33 in the radial direction R.
[0020] FIG. 4 is a conceptual diagram for explaining the configuration of the gap 52. In FIG. 4, the area indicated by the diagonal hatching is the housing 3, and the area indicated by the dotted hatching is the stator 1. However, in FIG. 4, the circumferential direction C, which is actually a curved line, is shown as a straight line for convenience of drawing. The upper part of FIG. 4 is the outside of the rotating electric machine 100, and the shaft 4 is disposed in the lower part of FIG. 4. The connection part 33 or the refrigerant flow path 34 is disposed in the central part in the thickness direction of the housing 3. In the holding part 51, the stator 1 and the housing 3 are in close contact with each other, and in the gap 52, the stator 1 and the housing 3 are not in contact with each other.
[0021] 4 illustrates gap 52 as spanning both stator 1 and housing 3, but gap 52 may exist only in the area of stator 1 or housing 3. For example, gap 52 may be formed by recessing only inner wall 31 of housing 3, or gap 52 may be formed by recessing only the outer periphery of stator 1, or gap 52 may be formed by recessing both inner wall 31 of housing 3 and the outer periphery of stator 1.
[0022] When the inner wall 31 of the housing 3 is recessed to form the gap 52, it can be said that the inner wall 31 is larger than the outer diameter of the stator 1 at least in a part of a position overlapping with the connection portion 33 in the radial direction R. When the outer periphery of the stator 1 is recessed to form the gap 52, it can be said that the outer diameter of the stator 1 is smaller than the inner diameter of the inner wall 31 at least in a part of a position overlapping with the connection portion 33 in the radial direction R.
[0023] 3, the housing 3 has a plurality of connection portions 33. It is preferable that the void portions 52 are provided so as to correspond to each of the plurality of connection portions 33, but the void portions 52 may be provided only for some of the connection portions 33. Furthermore, the plurality of void portions 52 may each have a different configuration. For example, one void portion 52 may be formed by recessing the inner wall 31 of the housing 3, and another void portion 52 may be formed by recessing the outer periphery of the stator 1.
[0024] The effect of providing a gap 52 between the outer peripheral surface of the stator 1 and the inner wall 31 at the surface where the inner wall 31 and the connection portion 33 of the housing 3 overlap in the radial direction R will be described. By providing the gap 52 between the inner wall 31 of the housing 3 and the outer peripheral surface of the stator 1, the propagation path of the vibration caused by the stator 1 is the stator 1, the inner wall 31 of the housing 3, the connection portion 33, and the outer wall 32 in that order, and a phase difference occurs between the vibration of the inner wall 31 and the vibration of the outer wall 32 of the housing 3. The phase difference between them reduces the excitation efficiency of the outer wall 32, reducing the vibration of the outer wall 32, which is the sound radiating surface, and thus the radiated sound can be reduced.
[0025] If the inner wall 31 of the housing 3 and the outer peripheral surface of the stator 1 were in close contact over the entire circumference, the housing 3 could be regarded as a single-layer wall at the connection 33, and the vibration of the stator 1 would be transmitted directly to the outer wall 32, causing the stator 1 and the housing 3 to vibrate in phase as a unit. In this case, the vibration would be larger than in the configuration of this embodiment, and the radiated sound would also be larger.
[0026] Fig. 5 is a diagram showing the relationship between the ratio of the contact area between the inner wall 31 of the housing 3 and the outer peripheral surface of the stator 1 and the volume of the radiated sound. The horizontal axis of Fig. 5 is the ratio of the contact area between the inner wall 31 and the outer peripheral surface of the stator 1 to the area of the inner wall 31 of the housing 3 or the outer peripheral surface of the stator 1. The vertical axis is the volume of the radiated sound when the contact area ratio is 100%, that is, the ratio based on the acoustic power.
[0027] When the contact area between the inner wall 31 of the housing 3 and the outer peripheral surface of the stator 1 is reduced from 100% to 80% or 60%, the proportion of acoustic power decreases. However, 40% is the lower limit, and when it is further reduced to 25%, the proportion of acoustic power increases. This phenomenon can be explained as follows. That is, by reducing the contact area, the path difference between the inner wall 31 and the outer wall 32 increases, and the phase difference between the vibration of the inner wall 31 and the vibration of the outer wall 32 increases. Then, when the phase difference between the vibration of the inner wall 31 and the vibration of the outer wall 32 of the housing 3 is 180°, that is, in opposite phase, the vibration of the outer wall 32 that radiates sound is minimized, and the radiated sound is minimized. However, when the phase difference increases further, it exceeds 180°, and it is considered that the vibration starts to increase.
[0028] In order to reduce radiated sound, it is sufficient that the inner wall 31 and the outer wall 32 of the housing 3 vibrate in opposite phases, and that the path difference between the inner wall 31 and the outer wall 32 is half the wavelength of the bending wave of the housing 3 caused by the circular zero-order vibration of the stator 1. In other words, it is preferable to set the interval at which the connecting parts 33 are provided, the length of the connecting parts 33, and the contact area between the inner wall 31 and the outer peripheral surface of the stator 1 so that the length from the start position of the gap 52 in the inner wall 31 of the housing 3, through the connecting parts 33, to the outer wall 32 is half the wavelength of the bending wave.
[0029] In Fig. 5, when the contact area between the inner wall 31 of the housing 3 and the outer peripheral surface of the stator 1 is about 40%, the path difference between the inner wall 31 and the outer wall 32 is half the wavelength of the bending wave of the housing 3 caused by the circular zero-order vibration of the stator 1, and the radiated sound is minimized. On the other hand, when the contact area between the inner wall 31 of the housing 3 and the outer peripheral surface of the stator 1 is reduced, the force suppressing the vibration of the stator 1 weakens, and the vibration of the stator 1 tends to increase. The balance between the vibration reduction effect due to the phase difference between the inner wall 31 and the outer peripheral surface of the housing 3 and the force suppressing the vibration of the stator 1 results in the radiated sound reduction effect due to the contact area between the inner wall 31 and the outer peripheral surface of the stator 1.
[0030] Figures 6 and 7 are diagrams showing specific examples of forming the gap 52. Figure 6 is a diagram showing the structure of the stator 1 in which the gap 52 is formed. Figure 7 is a diagram showing the structure of the housing 3 in which the gap 52 is formed.
[0031] 6 includes a retaining portion 11 having a diameter larger than the inner diameter of the inner wall 31 of the housing 3, and a gap forming portion 12 having a diameter smaller than the inner diameter of the inner wall 31. When shrink-fitting the stator 1 into the housing 3, the gap forming portion 12 of the stator 1 is disposed on a surface that overlaps with the connecting portion 33 of the housing 3 in the radial direction R, thereby forming the gap portion 52 in FIG.
[0032] The housing 3 shown in FIG. 7 includes a retaining portion 35 having a diameter smaller than the outer diameter of the stator 1, and a gap forming portion 36 having a diameter larger than the outer diameter of the stator 1. The stator 1 is shrink-fitted into the housing 3 of FIG. 7 to form the gap 52. As described above, the gap 52 may be formed in the shape of either the stator 1 or the housing 3, or the gap 52 may be formed in both the stator 1 and the housing 3. The method of forming the gap 52 is not limited to the above, and a shape such as a notch or any other arbitrary shape may be used.
[0033] According to the above-described first embodiment, the following advantageous effects can be obtained. (1) The rotating electric machine 100 includes a rotor 2, an annular stator 1 facing the rotor 2 with a predetermined gap therebetween, and a housing 3 in which the stator 1 is held. The housing 3 includes an inner wall 31 that holds the inner surface of the housing 3 in the radial direction R, an outer wall 32 that faces the inner wall 31 in the radial direction R, and a connecting portion 33 that connects the inner wall 31 and the outer wall 32. The inner wall 31, the outer wall 32, and the connecting portion 33 form a refrigerant flow path 34 through which a refrigerant can flow. The inner wall 31 has a gap portion 52 between the stator 1 and a surface that faces the stator 1 and at least partially overlaps with the connecting portion 33 in the radial direction. Therefore, a phase difference occurs between the vibration of the inner wall 31 and the vibration of the outer wall 32 of the housing 3, which reduces the vibration efficiency of the outer wall 32, which is the sound radiating surface, and the radiated sound can be reduced. Therefore, the radiated sound of the rotating electric machine can be reduced without increasing the cost of the number of parts.
[0034] (2) The gap 52 is provided at a position that overlaps the operative ends of the multiple connection portions 33 of the housing 3. Therefore, a phase difference between the inner wall 31 and the outer wall 32 can be reliably generated.
[0035] (3) The stator 1 is held in the housing 3 by shrink fitting.
[0036] (4) The outer diameter of the stator 1 is smaller than the inner diameter of the inner wall 31 at least in a portion of the position overlapping with the connection portion 33 in the radial direction R.
[0037] (5) The inner wall 31 is larger than the outer shape of the stator 1 at least in a portion where the inner wall 31 overlaps with the connecting portion 33 in the radial direction R.
[0038] (Variation 1) In the above-described embodiment, the thicknesses of the inner wall 31 and the outer wall 32 are not specified. However, as described below, the ratio of the thicknesses of the inner wall 31 and the outer wall 32 may be specified. Note that the weight of the housing 3 is assumed to be constant, and the relationship in magnitude between the thickness of the outer wall 32 and the thickness of the inner wall 31 of the housing 3 is considered.
[0039] First, consider the thickness of the inner wall 31 of the housing 3. The inner wall 31 is in close contact with the outer circumferential surface of the stator 1 at the retaining portion 51, and vibrates integrally with the stator 1. The material used for the housing 3 is generally aluminum, which has a Young's modulus approximately three times larger than that of the electromagnetic steel sheet used for the stator 1. Therefore, the thickness of the inner wall 31 of the housing 3 has little effect on the vibration when the stator 1 and the inner wall 31 are integrated.
[0040] Next, the thickness of the outer wall 32 of the housing 3 is considered. The outer wall 32 vibrates as a separate body from the stator 1 and the inner wall 31. Therefore, the rotating electric machine 100 has two vibration modes: a vibration mode in which the stator 1 and the inner wall 31 are integrated, and a vibration mode of the outer wall 32. In other words, in a graph of frequency and energy intensity, the rotating electric machine 100 has two peaks. In this modification, the peak intensity of the vibration mode in which the stator 1 and the inner wall 31 are integrated is called P1, and the peak intensity of the vibration mode of the outer wall 32 is called P2.
[0041] Regarding these two peak intensities, when the thickness of the outer wall 32 of the housing 3 is thinner than that of the inner wall 31, the peak P2 of the outer wall 32 is greater than the peak P1 of the stator 1 and the inner wall 31. On the other hand, when the thickness of the outer wall 32 of the housing 3 is made thicker than that of the inner wall 31, the outer wall 32 is made more rigid, the peak P2 of the outer wall 32 is made smaller, and the vibration of the outer wall 32 that radiates sound is reduced. Therefore, the peak P1 of the stator 1 and the inner wall 31 is also reduced, and the radiated sound can be reduced overall. Therefore, making the thickness of the outer wall 32 thicker than that of the inner wall 31 is advantageous in reducing radiated sound.
[0042] FIG. 8 is a diagram showing the effect of the ratio of the thickness of the inner wall 31 of the housing 3 to the thickness of the outer wall 32 on the volume of the radiated sound. The horizontal axis of FIG. 8 shows frequency, and the vertical axis shows the ratio of the radiated sound, i.e., the volume of acoustic power, based on the peak value of acoustic power in the housing 3 without a gap. The ratio of the thickness of the inner wall 31 of the housing 3 to the thickness of the outer wall 32 shown in the legend of FIG. 8 is shown as (thickness of the outer wall 32) / (thickness of the inner wall 31). That is, when the ratio is greater than 1, the outer wall 32 is thicker than the inner wall 31. Furthermore, in FIG. 8, conditions other than the thickness of the inner wall 31 and the thickness of the outer wall 32, for example, the radial dimension of the refrigerant flow path 34, are constant.
[0043] In the case of the ratio "0.5" shown by the dashed line in FIG. 8, a peak P2 of the outer wall 32 appears at the position of reference numeral 62, and a peak P1 of the stator 1 and the inner wall 31 appears at the position of reference numeral 61. In this case, there is a larger peak at around 5350 [Hz] than when there is no gap, and it is understood that it is not preferable to make the thickness of the outer wall 32 thin, as explained above. In contrast, in the characteristics shown by the dashed line and the two-dot dashed line, the peak is smaller than when there is no gap. In particular, in the case of the ratio "2", that is, when the outer wall 32 is twice as thick as the inner wall 31, the peak intensity is less than 0.5, which is less than half of the case when there is no gap.
[0044] Fig. 9 is a diagram showing the shape of the housing 3 in this modification. In the housing 3 shown in Fig. 9, the outer wall 32 is thicker than the inner wall 31. By having the housing 3 have the shape shown in Fig. 9, it is possible to reduce radiated sound generated by the rotating electric machine 100.
[0045] According to the first modification, the following advantageous effects can be obtained. (6) The thickness of the outer wall 32 is greater than the thickness of the inner wall 31. Therefore, the radiated sound generated by the rotating electric machine 100 can be further reduced.
[0046] (Variation 2) In the embodiment described above, the gap 52 has the same width as the connection portion 33 in the circumferential direction C, and the gap 52 and the connection portion 33 entirely overlap in the radial direction R. However, the gap 52 does not have to be the same as the connection portion 33 in the circumferential direction C, and it is sufficient that the gap 52 and the connection portion 33 at least partially overlap in the radial direction R.
[0047] FIG. 10 is a diagram showing variations of the gap 52. For convenience of drawing, reference numerals other than those of the gap 52 and the connection portion 33 are omitted in FIG. 10. As shown in FIG. 10(a), the gap 52 may have the same width as the connection portion 33 in the circumferential direction C, and a part of the gap 52 may overlap a part of the connection portion 33 in the radial direction R. As shown in FIG. 10(b), the width of the gap 52 in the circumferential direction C may be narrower than that of the connection portion 33, and the entire gap 52 may overlap a part of the connection portion 33 in the radial direction R. As shown in FIG. 10(c), the width of the gap 52 in the circumferential direction C may be wider than that of the connection portion 33, and a part of the gap 52 may overlap a part of the connection portion 33 in the radial direction R.
[0048] The above-mentioned embodiments and modifications may be combined with each other. Although various embodiments and modifications have been described above, the present invention is not limited to these. Other aspects that are conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. [Explanation of symbols]
[0049] 1: Stator 2: Rotor 3: Housing 31:Inner wall 32: Exterior wall 33: Connection part 34: Coolant flow path 51: Holding part 52:Void part 100: Rotating motor
Claims
1. A rotor; a stator having an annular shape facing the rotor with a predetermined distance therebetween; a housing in which the stator is held; The housing includes: an inner wall that holds an inner surface of the housing in a radial direction; an outer wall facing the inner wall in the radial direction; A connection portion that connects the inner wall and the outer wall, a refrigerant flow path through which a refrigerant can flow is formed by the inner wall, the outer wall, and the connecting portion; the inner wall has a surface facing the stator and at least a portion of which overlaps with the connection portion in the radial direction, and a gap is provided between the stator and the inner wall, No fluid flows through the gap.
2. 2. The rotating electric machine according to claim 1, The housing includes a plurality of the connection portions, The gap is provided at a position that overlaps all of the plurality of connection portions in the radial direction.
3. 2. The rotating electric machine according to claim 1, The stator is held in the housing by shrink fitting.
4. 2. The rotating electric machine according to claim 1, an outer diameter of the stator is smaller than an inner diameter of the inner wall at least in a portion of a position that overlaps with the connection portion in the radial direction;
5. 2. The rotating electric machine according to claim 1, The inner wall has a larger outer diameter than the stator at least in a portion of the position where the inner wall overlaps with the connection portion in the radial direction.
6. A rotating electric machine according to any one of claims 1 to 5, The rotating electric machine has an outer wall having a greater thickness than the inner wall.