Motor and its manufacturing method

Abstract

To provide technique enabling a housing and a stator to be easily positioned in a circumferential direction.SOLUTION: A motor comprises: a housing having a cylindrical inner peripheral surface; and a stator having an outer peripheral surface abutting on an inner peripheral surface from an inside in a radial direction. A plurality of groove portions extending in an axial direction and arranged in a circumferential direction are provided on the outer peripheral surface of the stator. At least one protruding portion is provided on the inner peripheral surface of the housing, the protruding portion abutting on an inner surface of any of the plurality of groove portions. The plurality of groove portions include: at least one first groove portion in which the protruding portion is present; and a second groove portion in which the protruding portion is not present.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a motor and a manufacturing method thereof. [Background technology]

[0002] Patent Document 1 discloses a motor. This motor includes a housing having a cylindrical inner peripheral surface, and a stator having an outer peripheral surface that abuts against the inner peripheral surface of the housing from the inside in the radial direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-172196 Summary of the Invention [Problem to be solved by the invention]

[0004] The motor of Patent Document 1 further includes a pin extending along the axial direction. This pin fits into the outer peripheral surface of the stator and the inner peripheral surface of the housing, thereby positioning the housing and the stator in the circumferential direction. For this reason, when manufacturing the motor of Patent Document 1, it is necessary to accurately position the outer peripheral surface of the stator and the inner peripheral surface of the housing in the circumferential direction.

[0005] This specification provides a technique that allows for easy positioning of the housing and the stator in the circumferential direction. [Means for solving the problem]

[0006] In a first aspect of the present technology, a motor may include a housing having a cylindrical inner circumferential surface and a stator having an outer circumferential surface abutting the inner circumferential surface from the inside in the radial direction. The outer circumferential surface of the stator may be provided with a plurality of grooves, each extending along the axial direction and arranged along the circumferential direction. The inner circumferential surface of the housing may be provided with at least one protrusion abutting an inner surface of any of the plurality of grooves. The plurality of grooves may include at least one first groove in which the protrusion is present and a second groove in which the protrusion is not present. In other words, the plurality of grooves may include at least one first groove with which the protrusion abuts, and a second groove with which the protrusion does not abut.

[0007] In the above configuration, the outer peripheral surface of the stator abuts against the inner peripheral surface of the housing from the radial inside, and the housing holds the stator by pressure acting on the stator from the housing. In this configuration, excessive pressure acting on the stator may unintentionally change the magnetic characteristics of the stator. In this regard, the above configuration has multiple grooves formed on the outer peripheral surface of the stator, which appropriately relieve the pressure acting on the stator. Additionally, the multiple grooves include first grooves with protrusions on the housing and second grooves without such protrusions. This configuration allows for easy circumferential positioning of the housing and the stator during motor manufacturing while utilizing the stress relief function of the multiple grooves.

[0008] In a second aspect, in the first aspect, the protrusion and the first groove may be in contact with each other with a gap therebetween. In other words, the protrusion and the first groove may be in partial contact with each other.

[0009] According to the above configuration, the pressure acting on the stator can be significantly alleviated even in the first groove portion that abuts against the protruding portion of the housing.

[0010] In a third aspect, in the first aspect, the protrusion and the first groove may be in contact with each other without any gap. In other words, the protrusion and the inner surface of the first groove may be in total contact with each other.

[0011] According to the above configuration, the housing and the stator can be accurately positioned in the circumferential direction.

[0012] In a fourth aspect, in any one of the first to third aspects, the inner circumferential surface of the housing may be provided with a plurality of protrusions, and the plurality of protrusions may be arranged at equal intervals in the circumferential direction.

[0013] According to the above configuration, the accuracy of alignment between the stator and the housing can be improved.

[0014] In a fifth aspect, in the fourth aspect, the plurality of grooves may be arranged at equal intervals in the circumferential direction.

[0015] According to the above configuration, the pressure acting on the stator can be equalized.

[0016] In a sixth aspect, in any one of the first to fifth aspects, the protrusion may extend along the axial direction.

[0017] According to the above configuration, the accuracy of alignment between the stator and the housing can be improved.

[0018] In a seventh aspect, in the sixth aspect, the protrusion may have a tapered section in which the protruding height from the inner peripheral surface increases toward one side in the axial direction.

[0019] According to the above configuration, when the housing and the stator are assembled together, the protruding portion of the housing can be easily positioned in the first groove portion of the stator.

[0020] In an eighth aspect, in any one of the first to seventh aspects, the housing may hold the stator by an interference fit.

[0021] According to the above-mentioned configuration, the stator can be firmly fixed to the housing. Note that, although this is an example, the above-mentioned configuration can be realized by shrink fitting, cold fitting, press fitting, or the like.

[0022] In a ninth aspect, a method for manufacturing a motor is disclosed. The method for manufacturing a motor may include the steps of: expanding an inner circumferential surface of a housing radially outward; arranging an outer circumferential surface of a stator to face the expanded inner circumferential surface of the housing; and contracting the inner circumferential surface of the housing to abut the inner circumferential surface against the outer circumferential surface of the stator. The outer circumferential surface of the stator may be provided with a plurality of grooves, each extending along the axial direction and arranged along the circumferential direction. The inner circumferential surface of the housing may be provided with at least one protrusion that abuts against an inner surface of one of the plurality of grooves. In the facing-arranging step, the housing and the stator may be positioned circumferentially so that the protrusion faces the groove. In other words, when the stator is disposed opposite the housing, the housing and the stator may be positioned in the circumferential direction so that the protrusion faces one of the plurality of grooves. In the abutting step, the plurality of grooves may include at least one first groove in which the protrusion is present and a second groove in which the protrusion is not present. In other words, in the abutting step, the protrusion abuts against at least one first groove portion of the plurality of groove portions, but does not necessarily abut against a second groove portion of the plurality of groove portions.

[0023] According to the above configuration, the plurality of grooves can exert a stress relief function, and the housing and the stator can be positioned in the circumferential direction.

[0024] In a tenth aspect, in the above ninth or tenth aspect, in the abutting step, the housing and the stator may be displaced relative to each other in the circumferential direction due to a force generated between the abutting protrusion and the inner surface of the first groove portion.

[0025] When the outer peripheral surface of the stator is disposed facing the expanded inner peripheral surface of the housing, the circumferential position of the stator relative to the housing may be slightly deviated from the desired position. With the above configuration, the housing and the stator are displaced relative to each other in the circumferential direction, allowing the stator to be moved to the desired position.

[0026] In an eleventh aspect, in the ninth aspect, in the contacting step, at least a part of the protruding portion may be plastically deformed by contact with the first groove portion.

[0027] According to the above configuration, the contact area between the protrusion and the first groove increases, so that the stator can be firmly fixed to the housing.

[0028] In a twelfth aspect, in the eleventh aspect, in the contacting step, the first groove may be filled without gaps with the plastically deformed protrusion.

[0029] According to the above configuration, the contact area between the protrusion and the first groove increases, so that the stator can be firmly fixed to the housing.

[0030] In a thirteenth aspect, in any one of the ninth to twelfth aspects, the abutting step may not cause plastic deformation in the protruding portion.

[0031] With this configuration, the contact area between the protrusion and the inner surface of the first groove can be made smaller than in a configuration in which plastic deformation occurs in the protrusion, thereby further reducing the pressure acting on the stator. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a cross-sectional view of a drive device 2 according to a first embodiment in a direction perpendicular to the axial direction. [Figure 2] 1 is an axial cross-sectional view of a drive device 2 according to a first embodiment. [Figure 3]2A to 2C are cross-sectional views taken in a direction perpendicular to the axial direction of the motor 10 according to the first embodiment during the manufacturing process. [Figure 4] 2A to 2C are axial cross-sectional views of the motor 10 according to the first embodiment in a manufacturing process. [Figure 5] 2A to 2C are axial cross-sectional views of the motor 10 according to the first embodiment in a manufacturing process. [Figure 6] FIG. 10 is an axial cross-sectional view of a driving device 202 according to a second embodiment. [Figure 7] 10A to 10C are axial cross-sectional views of a motor 210 according to a second embodiment in a manufacturing process. [Figure 8] FIG. 10 is an axial cross-sectional view of a driving device 302 according to a third embodiment. [Figure 9] 10A to 10C are axial cross-sectional views of a motor 310 according to a third embodiment in a manufacturing process. DETAILED DESCRIPTION OF THE INVENTION

[0033] (First Example) The drive device 2 will be described with reference to Figures 1 and 2. The drive device 2 includes a motor 10 and is mounted on an electric vehicle or the like. In this specification, a cylindrical coordinate system is defined with the rotation axis A of the motor 10 as a reference, and is composed of an axial direction D1, a radial direction D2, and a circumferential direction D3. The axial direction D1 is a direction parallel to the rotation axis A, and its coordinate axis is defined on the rotation axis. The radial direction D2 is a direction perpendicular to the axial direction D1, and is defined by a coordinate axis with the rotation axis A as its origin. The circumferential direction D3 is a direction perpendicular to the axial direction D1 and the radial direction D2, and is defined by a coordinate axis that revolves around the rotation axis A.

[0034] As shown in Fig. 1, the motor 10 includes a housing 12, a shaft 14, a rotor 16, and a stator 18. The shaft 14, the rotor 16, and the stator 18 are housed within the housing 12. Although not shown, the drive device 2 further includes a gear unit mechanically connected to the motor 10. The gear unit is disposed on one side of the motor 10 in the axial direction D1. The one side of the axial direction D1 is the right side in Fig. 1.

[0035] The shaft 14 extends along a rotation axis A. The rotation axis A is the center of rotation of the shaft 14. The shaft 14 is rotatably supported in the housing 12 by bearings. The rotor 16 is fixed to the shaft 14. The stator 18 is fixed to the housing 12 by shrink fitting. The stator 18 is made of a metal material such as iron or steel. As shown in FIG. 2 , the outer peripheral surface 20 of the stator 18 is provided with a plurality of grooves 22 extending along the axial direction D1. When viewed along the axial direction D1, the plurality of grooves 22 have a shape that curves along an arc. The plurality of grooves 22 are arranged at equal intervals along the circumferential direction D3. In this embodiment, eight grooves 22 are provided on the outer peripheral surface 20. The eight grooves 22 include four first grooves 24 in which first protrusions 40A (described later) are present and four second grooves 26 in which the first protrusions 40A are not present. The first groove portions 24 and the second groove portions 26 are arranged alternately in the circumferential direction D3.

[0036] The housing 12 in FIG. 1 is made of a metal material such as aluminum. The housing 12 is made of a material that is less hard than the stator 18. The housing 12 includes a central housing 30, a first cover 32, and a second cover 34. The central housing 30 has a cylindrical shape. The central housing 30 extends along the axial direction D1. Both ends of the central housing 30 in the axial direction D1 are open. The first cover 32 is attached to one end of the central housing 30 in the axial direction D1. The second cover 34 is attached to the other end of the central housing 30 in the axial direction D1.

[0037] As shown in FIG. 2 , the center housing 30 is formed with a plurality of axial flow passages 36 penetrating the center housing 30 in the axial direction D1. The plurality of axial flow passages 36 extend along the axial direction D1. The plurality of axial flow passages 36 are arranged at equal intervals in the circumferential direction D3. The inner circumferential surface 38 of the center housing 30 is provided with a plurality of first protrusions 40A that protrude inward in the radial direction D2. The plurality of first protrusions 40A extend along the axial direction D1. The plurality of first protrusions 40A are arranged at equal intervals in the circumferential direction D3. In this embodiment, four first protrusions 40A are provided on the inner circumferential surface 38. The first protrusions 40A are disposed inside the first grooves 24 of the stator 18. That is, the first protrusions 40A exist inside the first grooves 24 of the stator 18. The first protrusions 40A abut against the inner surface of the first grooves 24. The first protrusion 40A and the first groove 24 are in contact with each other with a gap therebetween. That is, a gap exists between the first protrusion 40A and the inner surface of the first groove 24. As shown in FIG. 1, the first protrusion 40A has a tapered section 42 and a flat section 44. The tapered section 42 is a section in which the protrusion height from the inner circumferential surface 38 increases toward one side in the axial direction D1. The protrusion height is the inner length in the radial direction D2. The flat section 44 is a section in which the protrusion height is constant. The first protrusion 40A abuts against the inner surface of the first groove 24 in the flat section 44. As shown in FIG. 2, when viewed along the axial direction D1, the first protrusion 40A in the tapered section 42 has a shape that curves along a circular arc. Furthermore, when viewed along the axial direction D1, the first protrusion 40A in the flat section 44 has a shape that is flattened from the shape that curves along a circular arc.

[0038] As shown in FIG. 1 , a plurality of first circumferential flow paths 50 are formed in the first cover 32. The plurality of first circumferential flow paths 50 are arranged along the circumferential direction D3. Each first circumferential flow path 50 connects two axial flow paths 36 that are adjacent to each other in the circumferential direction D3. Although not shown, a supply flow path through which a refrigerant is supplied is connected to one of the plurality of first circumferential flow paths 50. Furthermore, a discharge flow path that discharges the refrigerant to the outside is connected to one of the plurality of first circumferential flow paths 50.

[0039] A plurality of second circumferential flow passages 52 are formed in the second cover 34, and the plurality of second circumferential flow passages 52 are arranged along the circumferential direction D3. The second circumferential flow passages 52 connect two adjacent axial flow passages 36 in the circumferential direction D3. The plurality of first circumferential flow passages 50, the plurality of axial flow passages 36, and the plurality of second circumferential flow passages 52 form a single refrigerant system through which a refrigerant that cools the motor 10 flows.

[0040] (Method of manufacturing the motor 10) 1 to 4, a method for manufacturing the motor 10 will be described. This embodiment is characterized by the step of fixing the stator 18 to the central housing 30 of the housing 12. Therefore, only the step of fixing the stator 18 to the housing 12 will be described.

[0041] First, as shown in FIG. 3 , the central housing 30 of the housing 12 is heated to temporarily expand the inner circumferential surface 38 of the central housing 30 outward in the radial direction D2. Before the stator 18 is fixed to the central housing 30, the inner circumferential surface 38 includes a second protrusion 40B that has only a tapered section 46 and no flat section. The tapered section 46 is a section whose protruding height from the inner circumferential surface 38 increases toward one side in the axial direction D1. As shown in FIG. 4 , the second protrusion 40B has a shape that curves along a circular arc. The radius of curvature of the second protrusion 40B is smaller than the radius of curvature of the groove 22 of the stator 18. The inner circumferential surface 38 is preferably expanded so that the inner end of the tapered section 46 of the second protrusion 40B in the radial direction D2 coincides with the innermost portion of the groove 22 of the stator 18.

[0042] Next, the center housing 30 and the stator 18 are positioned in the circumferential direction D3 so that the second protrusion 40B on the inner circumferential surface 38 of the center housing 30 faces the first groove 24 of the center housing 30. Next, the stator 18 is moved in the axial direction D1 so that the outer circumferential surface 20 of the stator 18 faces the expanded inner circumferential surface 38 of the center housing 30. As a result, the second protrusion 40B on the inner circumferential surface 38 of the center housing 30 faces the first groove 24 of the center housing 30. Note that in FIG. 4 , the second protrusion 40B is positioned so that the center of the second protrusion 40B in the circumferential direction D3 coincides with the center of the first groove 24 in the circumferential direction D3.

[0043] Next, the center housing 30 is cooled, causing the inner circumferential surface 38 of the center housing 30 to shrink inward in the radial direction D2. As described above, the hardness of the center housing 30 is lower than that of the stator 18. Therefore, as the inner circumferential surface 38 shrinks, the second protrusion 40B of the center housing 30, which abuts against the inner surface of the first groove 24 of the stator 18, is crushed. That is, the second protrusion 40B undergoes plastic deformation and changes into the first protrusion 40A shown in FIG. 2. Furthermore, as the inner circumferential surface 38 shrinks, a portion of the inner circumferential surface 38 abuts against the outer circumferential surface 20 of the stator 18. Stress due to thermal contraction acts on this portion of the stator 18. This fixes the stator 18 to the center housing 30. That is, the center housing 30 holds the stator 18 by shrink fitting.

[0044] In the above configuration, when the outer peripheral surface 20 of the stator 18 is disposed opposite the expanded inner peripheral surface 38 of the center housing 30, as shown in FIG. 4 , the center of the second protrusion 40B in the circumferential direction D3 coincides with the center of the first groove 24 in the circumferential direction D3. However, as shown in FIG. 5 , there are cases where the center of the second protrusion 40B in the circumferential direction D3 does not coincide with the center of the first groove 24 in the circumferential direction D3. In such a situation, when the center housing 30 is cooled, a force is generated between the abutting second protrusion 40B and the inner surface of the first groove 24, causing the center housing 30 and the stator 18 to relatively displace in the circumferential direction D3. Specifically, the center housing 30 and the stator 18 are displaced relative to each other so that the center of the first groove 24 in the circumferential direction D3 coincides with the center of the second protrusion 40B in the circumferential direction D3. Similarly to the above, the second protrusion 40B undergoes plastic deformation, and stress due to thermal contraction acts on the stator 18. As a result, the central housing 30 and the stator 18 are aligned, and the stator 18 is fixed to the central housing 30.

[0045] As described above, as shown in FIGS. 1 and 2 , the motor 10 includes a housing 12 having a cylindrical inner circumferential surface 38 and a stator 18 having an outer circumferential surface 20 that abuts against the inner circumferential surface 38 from the inside in the radial direction D2. The outer circumferential surface 20 of the stator 18 is provided with a plurality of grooves 22 that each extend along the axial direction D1 and are arranged along the circumferential direction D3. The inner circumferential surface 38 of the housing 12 is provided with at least one first protrusion 40A (an example of a "protrusion") that abuts against the inner surface of one of the plurality of grooves 22. The plurality of grooves 22 includes at least one first groove 24 in which the first protrusion 40A is present and a second groove 26 in which the first protrusion 40A is not present.

[0046] In the above configuration, the outer peripheral surface 20 of the stator 18 abuts against the inner peripheral surface 38 of the housing 12 from the inside in the radial direction D2, and the housing 12 holds the stator 18 by pressure acting on the stator 18 from the housing 12. In this configuration, excessive pressure acting on the stator 18 may unintentionally change the magnetic characteristics of the stator 18. In this regard, in the above configuration, the outer peripheral surface 20 of the stator 18 is formed with multiple grooves 22, which appropriately relieve the pressure acting on the stator 18. In addition, the multiple grooves 22 include a first groove 24 in which a first protrusion 40A provided on the housing 12 is present and a second groove 26 in which no such protrusion is present. With this configuration, when manufacturing the motor 10, the multiple grooves 22 provide a stress relief function, and the housing 12 and the stator 18 can be easily positioned in the circumferential direction D3.

[0047] As shown in FIG. 2, the first protrusion 40A and the first groove 24 are in contact with each other with a gap therebetween.

[0048] According to the above configuration, the pressure acting on the stator 18 can be significantly alleviated even in the first groove portion 24 that abuts against the first protrusion portion 40A of the housing 12.

[0049] 2, a plurality of first protrusions 40A are provided on the inner circumferential surface 38 of the housing 12. The plurality of first protrusions 40A are arranged at equal intervals in the circumferential direction.

[0050] According to the above configuration, the accuracy of alignment between the stator 18 and the housing 12 can be improved.

[0051] As shown in FIG. 2, the plurality of grooves 22 are arranged at equal intervals in the circumferential direction.

[0052] According to the above configuration, the pressure acting on the stator 18 can be leveled.

[0053] As shown in FIG. 1, the first protrusion 40A extends along the axial direction D1.

[0054] According to the above configuration, the accuracy of alignment between the stator 18 and the housing 12 can be improved.

[0055] As shown in FIG. 1, the first protruding portion 40A has a tapered section 42 whose protruding height from the inner circumferential surface 38 increases toward one side in the axial direction D1.

[0056] According to the above configuration, the first protrusion 40A of the housing 12 can be easily positioned relative to the first groove 24 of the stator 18 when the housing 12 and the stator 18 are assembled together.

[0057] The housing 12 also holds the stator 18 by shrink fitting (an example of an "interference fit").

[0058] According to the above configuration, the stator 18 can be firmly fixed to the housing 12.

[0059] As shown in Figures 1 to 4, the manufacturing method of motor 10 includes the steps of expanding inner circumferential surface 38 of housing 12 outward in radial direction D2, arranging outer circumferential surface 20 of stator 18 opposite the expanded inner circumferential surface 38 of housing 12, and contracting inner circumferential surface 38 of housing 12 so that the inner circumferential surface 38 abuts against outer circumferential surface 20 of stator 18.

[0060] According to the above configuration, the plurality of grooves 22 can exert a stress relief function, and the housing 12 and the stator 18 can be positioned in the circumferential direction.

[0061] Furthermore, in the process of abutting the inner peripheral surface 38 against the outer peripheral surface 20 of the stator 18, the force generated between the second protrusion 40B (an example of a "protrusion") and the inner surface of the first groove portion 24 causes the housing 12 and the stator 18 to displace relative to each other in the circumferential direction.

[0062] When the outer peripheral surface 20 of the stator 18 is disposed opposite the expanded inner peripheral surface 38 of the housing 12, the position of the stator 18 in the circumferential direction D3 relative to the housing 12 may be slightly deviated from a desired position. With the above configuration, the housing 12 and the stator 18 are displaced relative to each other in the circumferential direction D3, thereby allowing the position of the stator 18 in the circumferential direction D3 to be moved to a desired position.

[0063] Furthermore, in the process of bringing the inner peripheral surface into contact with the outer peripheral surface 20 of the stator 18, at least a portion of the second protrusion 40B is plastically deformed by contact with the first groove .

[0064] According to the above configuration, the contact area between the second protrusion 40B and the first groove 24 is increased, so that the stator 18 can be firmly fixed to the housing 12. Furthermore, in the configuration in which the stator 18 is cooled using the refrigerant system of the housing 12 as described above, the cooling performance can be improved.

[0065] (Second Example) A drive device 202 of the second embodiment will be described with reference to Figure 6. In the drive device 202 of this embodiment, the configuration of the central housing 230 of the motor 210 is different from the central housing 30 of the motor 10 of the first embodiment. Note that, in the following, components common to the embodiments will be assigned the same reference numerals and descriptions thereof will be omitted.

[0066] The inner circumferential surface 238 of the center housing 230 is provided with a plurality of first protrusions 240A that protrude inward in the radial direction D2. The plurality of first protrusions 240A extend along the axial direction D1. The plurality of first protrusions 240A are arranged at equal intervals in the circumferential direction D3. In this embodiment, four first protrusions 240A are provided on the inner circumferential surface 238. The first protrusions 240A are disposed inside the first grooves 24 of the stator 18. The first protrusions 240A abut against the inner surfaces of the first grooves 24. The first protrusions 240A and the first grooves 24 are in contact with each other with a gap therebetween. That is, a gap exists between the first protrusions 240A and the inner surfaces of the first grooves 24. The first protrusions 240A abut against the inner surfaces of the first grooves 24 between one end and the other end of the stator 18 in the axial direction D1. When viewed along the axial direction D1, the first protrusion 240A has a constant shape that curves along an arc.

[0067] (Method of manufacturing the motor 10) A manufacturing method for the motor 210 of the second embodiment will be described with reference to Figures 6 and 7. Note that the process of temporarily expanding the inner circumferential surface 238 of the center housing 230 outward in the radial direction D2 and the process of arranging the outer circumferential surface 20 of the stator 18 to face the expanded inner circumferential surface 238 are the same as those in the first embodiment, and therefore a description of these processes will be omitted.

[0068] After the outer peripheral surface 20 of the stator 18 is positioned facing the expanded inner peripheral surface 238 of the central housing 230, the central housing 230 is cooled, causing the inner peripheral surface 238 of the central housing 230 to contract inward in the radial direction D2. In FIG. 6 , the center position of the second protrusion 240B of the central housing 230 in the circumferential direction D3 does not coincide with the center position of the first groove 24 of the stator 18 in the circumferential direction D3. In this case, the force generated between the abutting second protrusion 240B and the inner surface of the first groove 24 causes the central housing 230 and the stator 18 to relatively displace in the circumferential direction D3. Furthermore, as the inner peripheral surface 238 of the central housing 230 contracts, a portion of the inner peripheral surface 238 comes into contact with the outer peripheral surface 20 of the stator 18. In this embodiment, the inner peripheral surface 238 is contracted so as not to cause plastic deformation of the second protrusion 240B of the central housing 230. As a result, as shown in Fig. 6, the innermost portion in the radial direction D2 of the second protrusion 240B of the central housing 230 comes into contact with the innermost portion in the radial direction D2 of the first groove portion 24 of the stator 18. Therefore, the shape of the second protrusion 240B (see Fig. 7) before the stator 18 is fixed to the central housing 230 is the same as the shape of the first protrusion 240A after the stator 18 is fixed to the central housing 230.

[0069] As described above, in the process of bringing the inner circumferential surface 238 of the central housing 230 into contact with the outer circumferential surface 20 of the stator 18, no plastic deformation occurs in the second protrusion 240B (an example of a "protrusion").

[0070] According to the above configuration, compared to a configuration in which plastic deformation occurs in the second protruding portion 240B, it is possible to reduce the contact area between the second protruding portion 240B and the inner circumferential surface 238. Therefore, it is possible to further reduce the pressure acting on the stator 18.

[0071] (Third Example) A driving device 302 of the third embodiment will be described with reference to Figure 8. In the driving device 302 of this embodiment, the configuration of a central housing 330 of a motor 310 differs from that of the central housing 30 of the motor 10 of the first embodiment.

[0072] The inner circumferential surface 338 of the central housing 330 is provided with a plurality of first protrusions 340A that protrude inward in the radial direction D2. In FIG. 8, the plurality of first protrusions 340A are indicated in gray for ease of understanding. The plurality of first protrusions 340A extend along the axial direction D1. The plurality of first protrusions 340A are arranged at equal intervals in the circumferential direction D3. In this embodiment, four first protrusions 340A are provided on the inner circumferential surface 338. The first protrusions 340A are filled inside the first grooves 24 of the stator 18. That is, the first protrusions 340A and the first grooves 24 are in contact with each other without any gaps. Therefore, when viewed along the axial direction D1, the first protrusions 340A have a shape corresponding to the first grooves 24.

[0073] (Method of manufacturing the motor 10) A manufacturing method for the motor 310 of the third embodiment will be described with reference to Figures 8 and 9. As with the second embodiment, the description of the process of temporarily expanding the inner circumferential surface 338 of the center housing 330 outward in the radial direction D2 and the process of arranging the outer circumferential surface 20 of the stator 18 to face the expanded inner circumferential surface 338 will be omitted.

[0074] As shown in FIG. 9 , after the outer peripheral surface 20 of the stator 18 is positioned facing the expanded inner peripheral surface 338 of the center housing 330, the center housing 330 is cooled, causing the inner peripheral surface 338 of the center housing 330 to contract inward in the radial direction D2. In FIG. 9 , the center position of the second protrusion 340B of the center housing 330 in the circumferential direction D3 does not coincide with the center position of the first groove 24 of the stator 18 in the circumferential direction D3. In this case, the center housing 330 and the stator 18 are relatively displaced in the circumferential direction D3 due to a force generated between the abutting second protrusion 340B and the inner surface of the first groove 24. Furthermore, as the inner peripheral surface 338 of the center housing 330 contracts, a portion of the inner peripheral surface 338 comes into contact with the outer peripheral surface 20 of the stator 18. Furthermore, the second protrusion 340B of the central housing 330 is crushed in response to contact with the inner surface of the first groove 24 of the stator 18. That is, the second protrusion 340B is plastically deformed. In this embodiment, the inner circumferential surface 338 of the central housing 330 is contracted so that the second protrusion 340B of the central housing 330 fills the first groove 24 of the stator 18. As a result, as shown in FIG. 8 , the first protrusion 340A fills the first groove 24 of the stator 18.

[0075] As described above, as shown in FIG. 8, the first protrusion 340A (an example of a "protrusion") and the first groove 24 come into contact with each other without any gap.

[0076] With the above configuration, the contact area between the first protrusion 340A and the first groove 24 can be increased compared to a configuration in which the first protrusion 340A and the first groove 24 are in contact with each other with a gap therebetween. Therefore, the stator 18 can be firmly fixed to the housing 12 by the first groove 24. Furthermore, in a configuration in which the stator 18 is cooled using the refrigerant system of the housing 12, increasing the contact area between the housing 12 and the stator 18 improves heat transfer. That is, cooling performance can be improved. With the above configuration, the contact area between the first protrusion 340A and the first groove 24 is increased compared to a configuration in which the first protrusion 340A and the first groove 24 are in contact with each other with a gap therebetween. Therefore, cooling performance can be improved.

[0077] Furthermore, in the process of bringing the inner peripheral surface 338 into contact with the outer peripheral surface 20 of the stator 18, the plastically deformed first protrusion 340A fills the first groove 24 without leaving any gaps.

[0078] According to the above configuration, the contact area between the second protrusion 340B and the first groove 24 is increased, so that the stator 18 can be firmly fixed to the housing 12. Furthermore, in the configuration in which the refrigerant system of the housing 12 is used to cool the stator 18 as described above, the cooling performance can be improved.

[0079] While specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

[0080] (First Modification) In each of the above embodiments, one first protrusion 40A, 240A, 340A exists in one first groove 24. A plurality of first protrusions 40A, 240A, 340A may exist in one first groove 24.

[0081] (Second Modification) The plurality of first protrusions 40A, 240A, 340A do not have to be arranged at equal intervals in the circumferential direction D3.

[0082] (Third Modification) The plurality of grooves 22 do not have to be arranged at equal intervals in the circumferential direction D3.

[0083] (Fourth Modification) The first protrusions 40A, 240A, 340A do not have to extend along the axial direction D1. That is, in the axial direction D1, the first protrusions 40A, 240A, 340A may be provided in a portion of the first groove 24. As an example, the first protrusions 40A, 240A, 340A may be provided only in the center of the first groove 24 in the axial direction D1.

[0084] (Fifth Modification) The shape of the protrusions present in each first groove portion 24 may be different. For example, the cross-sectional shape of the protrusions present in each first groove portion 24 may be triangular or the like. Furthermore, the shape of each first groove portion 24 may be different to match the shape of the protrusions.

[0085] Furthermore, the technical elements described in this specification or drawings may exhibit technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings may achieve multiple objectives simultaneously, and achieving one of those objectives alone is technically useful. [Explanation of symbols]

[0086] 2: drive unit, 10: motor, 12: housing, 14: shaft, 16: rotor, 18: stator, 20: outer circumferential surface, 22: groove, 24: first groove, 26: second groove, 30: central housing, 32: first cover, 34: second cover, 36: axial flow path, 38: inner circumferential surface, 40A: first protrusion, 40B: second protrusion, 42: tapered section, 44: flat section, 46: tapered section, 50: first circumferential flow path, 52: second circumferential flow path, 202: drive unit, 210: motor, 230: central housing, 238: inner circumferential surface, 240A: first protrusion, 240B: second protrusion, 302: drive unit, 310: motor, 330: central housing, 338: inner circumferential surface, 340A: first protrusion, 340B: second protrusion

Claims

1. a housing having a cylindrical inner circumferential surface; a stator having an outer circumferential surface that abuts against the inner circumferential surface from the inside in the radial direction; Equipped with The outer peripheral surface of the stator is provided with a plurality of grooves, each extending along the axial direction and arranged along the circumferential direction, At least one protrusion is provided on the inner circumferential surface of the housing, the protrusion abutting against an inner surface of any one of the plurality of grooves, the plurality of grooves include at least one first groove with which the protruding portion abuts and a second groove with which the protruding portion does not abut, The protrusion is in contact with a part of the inner surface of the first groove, and a gap exists between the inner circumferential surface of the housing and the inner surface of the first groove on both sides of the protrusion in the circumferential direction. Motor.

2. a plurality of the protrusions are provided on the inner circumferential surface of the housing, The motor according to claim 1 , wherein the plurality of protrusions are arranged at equal intervals in the circumferential direction.

3. The motor according to claim 2 , wherein the plurality of grooves are arranged at equal intervals in the circumferential direction.

4. The motor according to claim 1 , wherein the protrusion extends along the axial direction.

5. The motor according to claim 4 , wherein the protruding portion has a tapered section in which the protruding height from the inner peripheral surface increases toward one side in the axial direction.

6. The motor of claim 1 , wherein the housing retains the stator by an interference fit.

7. A motor as described in claim 6, wherein the housing is made of a material having a lower hardness than the stator.

8. A method for manufacturing a motor, comprising: a step of radially outwardly expanding an inner circumferential surface of a housing made of a metal material; disposing an outer peripheral surface of a stator opposite the expanded inner peripheral surface of the housing; contracting the inner circumferential surface of the housing to bring the inner circumferential surface into contact with the outer circumferential surface of the stator; Equipped with The outer peripheral surface of the stator is provided with a plurality of grooves, each extending along the axial direction and arranged along the circumferential direction, At least one protrusion is provided on the inner circumferential surface of the housing, the protrusion abutting against an inner surface of any one of the plurality of grooves, When the stator is disposed opposite the housing, the housing and the stator are positioned in the circumferential direction so that the protrusion faces one of the plurality of grooves, In the abutting step, the protrusion abuts against at least one first groove portion among the plurality of groove portions, but does not abut against a second groove portion among the plurality of groove portions, In the abutting step, the housing and the stator are positioned in the circumferential direction while being displaced relative to each other in the circumferential direction by a force generated between the protrusion and the inner surface of the first groove portion, which are in contact with each other. Manufacturing method.

9. The manufacturing method according to claim 8 , wherein in the contacting step, at least a portion of the protrusion is plastically deformed by contact with the first groove portion.

10. The manufacturing method according to claim 9 , wherein in the abutting step, the first groove is filled without gaps with the plastically deformed protrusion.

11. The manufacturing method according to claim 8 , wherein the step of bringing the protrusion into contact with the substrate does not cause plastic deformation of the protrusion.

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