Rotating electric machine and method for manufacturing the same

Abstract

To fix a case and a stator so that they do not rotate relative to each other by a simpler structure.SOLUTION: A rotary electric machine 20 comprises: a stator core 25 arranged on an outer side R1 in a radial direction R with respect to a rotor 21; and a case 1 provided with an inner circumferential surface 11a facing an outer circumferential surface 25b of the stator core 25. The outer circumferential surface 25b of the stator core 25 and the inner circumferential surface 11a of the case 1 are fitted to each other by interference fitting. A convex or concave locking portion 3 is formed at at least one position in a circumferential direction C on either the outer circumferential surface 25b of the stator core 25 or the inner circumferential surface 11a of the case 1.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a rotating electric machine including a stator arranged radially outward from a rotor and a case having an inner circumferential surface facing the outer circumferential surface of the stator, and a method for manufacturing the rotating electric machine. [Background technology]

[0002] JP 2015-34754 A discloses a rotating electric machine (MG) equipped with a key structure (key engagement portion (30)) for restricting circumferential movement of a stator (11) relative to a case (101) that houses an inner rotor type rotating electric machine (reference numerals in parentheses in the Background Art are those of the referenced document). This key structure is composed of a key projection (31) protruding radially outward from the outer circumferential surface of the stator (11) and a key groove (32) formed on the inner circumferential surface of the case (101) facing the outer circumferential surface of the stator (11) so as to retract radially outward. The key groove (32) and the key projection (31) engage with each other to restrict circumferential movement of the stator (11) relative to the case (101). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-34754 A Summary of the Invention [Problem to be solved by the invention]

[0004] When the above-mentioned key structure is provided, processing costs are incurred for both the case and the stator, which may increase the production cost of the rotating electric machine. In addition, a clearance is required between the key groove and the key protrusion, and the case and the stator rotate slightly relative to each other within the range of this clearance. This relative rotation may cause vibration and noise.

[0005] Therefore, a technique is desired that can fix the case and the stator so as not to rotate relative to each other using a simpler structure. [Means for solving the problem]

[0006] In consideration of the above problems, the rotating electric machine of the present invention comprises a stator core arranged radially outward from a rotor, and a case having an inner circumferential surface facing the outer circumferential surface of the stator core, wherein the outer circumferential surface of the stator core and the inner circumferential surface of the case are fitted together in a tight fit, and a convex or concave engagement portion is formed at at least one location in the circumferential direction on either the outer circumferential surface of the stator core or the inner circumferential surface of the case.

[0007] The boundary portion between the case and the stator core facing each other in the radial direction is circular in the axial view along the direction of the rotation axis of the rotating electric machine. According to this configuration, a locking portion is formed on either the outer peripheral surface of the stator core or the inner peripheral surface of the case, and the outer peripheral surface of the stator core and the inner peripheral surface of the case are fitted together by an interference fit, so that the locking portion is inserted into the other of the outer peripheral surface of the stator core and the inner peripheral surface of the case by the pressure of the interference fit. This suppresses relative movement of the stator core and the case in the circumferential direction at the circular boundary portion. Since the locking portion only needs to be formed on either the outer peripheral surface of the stator core or the inner peripheral surface of the case, it is easy to provide the locking portion. Thus, according to this configuration, the case and the stator can be fixed so as not to rotate relative to each other with a simpler structure.

[0008] In addition, in consideration of the above-mentioned problems, the manufacturing method of a rotating electric machine of the present invention is a manufacturing method of a rotating electric machine including a stator core and a case having an inner circumferential surface facing the outer circumferential surface of the stator core, wherein the stator core and the case are fitted together so that the outer circumferential surface of the stator core and the inner circumferential surface of the case are in a tight fit with each other, with a convex or concave engagement portion formed at at least one circumferential location on either the outer circumferential surface of the stator core or the inner circumferential surface of the case.

[0009] According to this manufacturing method, the outer peripheral surface of the stator core and the inner peripheral surface of the case are fitted together in a tight fit state with a locking portion formed on either the outer peripheral surface of the stator core or the inner peripheral surface of the case, so that the locking portion is embedded in the other of the outer peripheral surface of the stator core and the inner peripheral surface of the case by the pressure of the tight fit. This suppresses relative movement of the stator core and the case in the circumferential direction at the circular boundary portion that faces the case and the stator core in the radial direction when viewed in the axial direction. Since the locking portion only needs to be formed on either the outer peripheral surface of the stator core or the inner peripheral surface of the case, it is easy to provide the locking portion. In this way, according to this manufacturing method, the case and the stator can be fixed so as not to rotate relative to each other with a simpler structure.

[0010] Further features and advantages of the rotating electric machine and the manufacturing method for the rotating electric machine will become apparent from the following description of the embodiments explained with reference to the drawings. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an axial cross-sectional view showing an example of a rotating electric machine. [Diagram 2] FIG. 1 is a radial cross-sectional view showing an example of a rotating electric machine; [Diagram 3] FIG. 1 is a diagram showing a first example of a locking portion in a relationship before the case and the stator core are fitted together; [Figure 4] FIG. 1 is a diagram showing a first example of a locking portion after the case and the stator core are fitted together; [Diagram 5] FIG. 1 is a diagram showing a first example of a locking portion after a case having a target portion is fitted to a stator core; [Figure 6] FIG. 13 is a diagram showing a second example of a locking portion in a relationship before the case and the stator core are fitted together. [Figure 7] FIG. 13 is a diagram showing a second example of the locking portion after the case and the stator core are fitted together. [Figure 8] FIG. 13 is a diagram showing the relationship between the step of the locking portion and the amount of thermal expansion of the case in the second example. [Figure 9] FIG. 13 is a diagram showing a third example of a locking portion in a relationship before the case and the stator core are fitted together. [Figure 10] FIG. 13 is a diagram showing a third example of the locking portion after the case and the stator core are fitted together. [Figure 11] FIG. 13 is a diagram showing the relationship between the step of the locking portion and the amount of thermal expansion of the case in the third example. [Figure 12] FIG. 13 is a radial cross-sectional view showing another example of a rotating electric machine; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the rotating electric machine will be described with reference to the drawings. FIG. 1 is an axial cross-sectional view showing an example of a vehicle drive device 100 including a rotating electric machine 20, and FIG. 2 is a radial cross-sectional view of the rotating electric machine 20. The vehicle drive device 100 is, for example, a drive device mounted on a hybrid vehicle or an electric vehicle that uses an internal combustion engine (not shown) and a rotating electric machine 20 as a driving force source for wheels. In the following description, when the expression "tubular" or "cylindrical" is used, it means that the overall general shape is a tube or a cylinder even if it has some irregular parts. This is not limited to these, and the same applies to other expressions using "shape" with respect to shape, etc. In addition, the direction along the rotation axis (rotor shaft 27) of the rotating electric machine 20 is the axial direction L, the outside of the radial direction R (opposite the rotor shaft 27) is the radial outside R1, the inside of the radial direction R (direction of the rotor shaft 27) is the radial inside R2, and the rotation direction of the rotor 21 is the circumferential direction C.

[0013] The rotating electric machine 20 is a permanent magnet type rotating electric machine including a rotor 21 having a permanent magnet 23 inside a rotor core 22, a stator 24 having a stator coil 26 wound around a stator core 25, and a rotor shaft 27 connected to the rotor core 22. The stator 24 is disposed on the radially outer side R1 of the rotor 21, and the rotating electric machine 20 is an inner rotor type rotating electric machine. The rotor shaft 27 is connected to the rotor core 22 on the radially inner side R2 of the rotor core 22, and the rotor 21 and the rotor shaft 27 rotate integrally. In this embodiment, the rotating electric machine 20 is a permanent magnet type rotating electric machine, but may be another type of rotating electric machine, such as an induction type rotating electric machine.

[0014] The rotating electric machine 20 includes a stator 24, a rotor 21, a case 1 that houses the stator 24 and the rotor 21, and a water jacket 2 disposed on the radially outer side R1 of the case 1. The case 1 may be referred to as an inner case, and the water jacket 2 and the case 2 may be referred to as an outer case. As shown in FIG. 1, the stator core 25 is disposed on the radially outer side R1 with respect to the rotor 21. The case 1 includes a case cylindrical portion 11 having a peripheral wall portion, and an inner peripheral surface of the case cylindrical portion 11 that faces a stator core outer peripheral surface 25b, which is the outer peripheral surface of the stator core 25, is referred to as a case inner peripheral surface 11a. The stator core 25 is fixed to the case 1 by fitting the case inner peripheral surface 11a and the stator core outer peripheral surface 25b by interference fit.

[0015] As shown in FIG. 1, a groove 15 is formed on the case outer peripheral surface 11b, which is the outer peripheral surface of the case cylindrical portion 11, so as to have a portion that abuts against the jacket inner peripheral surface 12a, which is the inner peripheral surface of the jacket cylindrical portion 12 of the water jacket 2, and a portion that is separated from the jacket inner peripheral surface 12a. As a result, a refrigerant flow path 16 through which the refrigerant flows along the axial direction L is formed between the case cylindrical portion 11 and the jacket cylindrical portion 12. As shown in FIG. 2, a plurality of grooves 15 are formed in the circumferential direction C of the case outer peripheral surface 11b. As described above, the stator 24 is fixed to the case 1 in a state in which the stator core outer peripheral surface 25b abuts against the case inner peripheral surface 11a of the case cylindrical portion 11. Since the stator 24 and the case 1 are in close contact with each other, the efficiency of heat exchange with the refrigerant flow path 16 formed between the case cylindrical portion 11 and the jacket cylindrical portion 12 is increased, and the stator 24 can be efficiently cooled.

[0016] As shown in FIG. 2, the stator core outer peripheral surface 25b is provided with a plurality of concave locking portions 3 recessed toward the radially inner side R2. However, as will be described below with various examples, the locking portions 3 may be formed in a convex or concave shape at least at one location in the circumferential direction C on either the stator core outer peripheral surface 25b or the case inner peripheral surface 11a. The boundary portion between the case 1 and the stator core 25 facing each other in the radial direction R is circular as viewed in the axial direction as shown in FIG. 2. The locking portions 3 are formed at this boundary portion, and the stator core outer peripheral surface 25b and the case inner peripheral surface 11a are fitted together by interference fit, so that the locking portions 3 are bitten into either the stator core outer peripheral surface 25b or the case inner peripheral surface 11a by the pressure of the interference fit. This suppresses the relative movement of the stator core 25 and the case 1 in the circumferential direction C at the circular boundary portion.

[0017] The locking portion 3 may be formed at least at one location in the circumferential direction C, but is preferably provided at multiple locations in the circumferential direction C as shown in Fig. 2. When the locking portions 3 are formed at multiple locations in the circumferential direction C, the stator core 25 and the case 1 come into strong contact with each other at multiple locations in the circumferential direction C, increasing the frictional force between the stator core 25 and the case 1 and more strongly restricting the relative movement in the circumferential direction C.

[0018] 2, in this embodiment, the locking portion 3 is provided on the outer peripheral surface 25b of the stator core. In this example, the stator core 25 is formed by stacking a plurality of core plates, which are formed by punching electromagnetic steel sheets, in the axial direction L. Therefore, in order to form the locking portion 3 in the stator core 25, a die for punching the electromagnetic steel sheets may be configured so that protrusions that become the locking portions 3 and are stacked in the axial direction L are formed on the core plates. Therefore, the locking portion 3 can be provided in the stator core 25 while minimizing increases in production costs.

[0019] Although the locking portion 3 is not prevented from being formed in a dot shape, it is preferable that the locking portion 3 is formed to extend along the axial direction L. By forming the locking portion 3 long in the axial direction L, the region in the axial direction L in which the locking portion 3 is biting into the case inner peripheral surface 11a becomes large, so that the frictional force between the stator core 25 and the case 1 increases, and the relative movement in the circumferential direction C is more strongly restricted. Preferably, the locking portion 3 is formed so as to be continuous over the entire region in the axial direction L in the region where the stator core outer peripheral surface 25b and the case inner peripheral surface 11a face each other (axial facing region A (see FIG. 1)). In this way, the locking portion 3 formed on either the outer peripheral surface of the stator core or the inner peripheral surface of the case is biting into the case inner peripheral surface 11a over the entire region in the axial direction facing region A. Therefore, the relative movement in the circumferential direction C between the stator core outer peripheral surface 25b and the case inner peripheral surface 11a can be more firmly restricted.

[0020] A first example of the locking portion 3 will be described below with reference to Figs. 3 to 5 which illustrate the locking portion 3 having a recess 31 formed in a concave shape on the outer peripheral surface 25b of the stator core. The locking portion 3 shown in Fig. 2 also has a recess 31. Fig. 3 shows the locking portion 3 of the first example in a relationship before the case 1 and the stator core 25 are fitted together, and Fig. 4 shows the locking portion 3 of the first example in a relationship after the case 1 and the stator core 25 are fitted together. Fig. 5 is a diagram for explaining a target portion 5 (described later) in a state after the case 1 and the stator core 25 are fitted together.

[0021] The case 1 and the stator core 25 are fixed by shrink fitting, for example, by heating the case 1 to expand it, and housing the stator core 25 in the case cylindrical portion 11 of the case 1 (first step #1), and then cooling the case 1 to contract it, thereby fitting the case 1 and the stator core 25 together (second step #2). As shown in Fig. 3, which shows one state in the first step #1, the stator core 25 is housed in the case 1, which has been heated and expanded radially outward R1, with a certain amount of clearance between the stator core outer peripheral surface 25b and the case inner peripheral surface 11a.

[0022] 4 shows a state in which the heated case 1 houses the stator core 25 and the case 1 cools and shrinks, bringing the stator core outer peripheral surface 25b and the case inner peripheral surface 11a into close contact (one state in the second step #2). At this time, in the locking portion 3 formed by the recess 31, the stator core outer peripheral surface 25b is recessed toward the radially inward side R2, so that the case inner peripheral surface 11a protrudes toward the radially inward side R2 to form a protruding portion 11p. By engaging the recess 31 with the protruding portion 11p, the relative movement between the stator core 25 and the case 1 in the circumferential direction C is restricted.

[0023] As described above with reference to FIG. 1 and FIG. 2, the groove portion 15 that becomes the refrigerant flow path 16 is formed in the case 1. The portion where the groove portion 15 is formed is thinner in the radial direction R of the case cylindrical portion 11 than other portions. Here, the portion where the groove portion 15 is formed is called the target portion 5, and the other portions are called the non-target portion 6. The rigidity of the target portion 5 in the radial direction R is weaker than the rigidity of the non-target portion 6 in the radial direction R. Therefore, the target portion 5 is more likely to deform along the radial direction R than the non-target portion 6. When the locking portion 3 is provided on the stator core outer peripheral surface 25b and the case 1 includes the target portion 5 that has a weaker strength in the radial direction R than other portions (non-target portion 6) in the circumferential direction C, if the target portion 5 and the locking portion 3 overlap as viewed in the radial direction R as shown in FIG. 2 and FIG. 5, the protruding portion 11p described above is more likely to be formed. The same applies to recessed portions 11d (see FIGS. 7 and 10) in second and third examples described later.

[0024] The locking portion 3 is provided on the outer peripheral surface 25b of the stator core, and when the case 1 and the stator core 25 are fitted together by tight fitting such as shrink fitting as described above, the case 1 side deforms in response to the locking portion 3. By providing the target portion 5 whose rigidity in the radial direction R is lower than that of the non-target portion 6, the case 1 deforms appropriately in response to the locking portion 3, and the above-mentioned protruding portion 11p (see Figs. 4 and 5) and the recessed portion 11d (see Figs. 7 and 10) described later are appropriately formed. Therefore, the relative movement between the stator core 25 and the case 1 in the circumferential direction C can be more firmly restricted.

[0025] In addition, FIG. 2 illustrates an example in which all of the locking portions 3 formed at multiple locations overlap the groove portions 15 corresponding to the target portion 5 in a radial view. However, even if the locking portions 3 are formed at multiple locations, only some of the locking portions 3 may overlap the target portion 5 in a radial view. As shown in FIG. 2, the groove portions 15 that become the target portion 5 may be formed in a location that does not overlap the locking portions 3 in a radial view. In addition, in the present embodiment, an example is given in which the groove portions 15 for forming the refrigerant flow paths 16 become the target portion 5, but the target portion 5 may be formed simply as a location with low rigidity in the radial direction R without being used for other purposes such as the refrigerant flow paths 16. In addition, it is of course not prevented that the target portion 5 with low rigidity in the radial direction R is not formed, and the entire circumferential direction C is the non-target portion 6.

[0026] 6 to 8, a second example of the locking portion 3 will be described below with reference to the drawings, which illustrate a configuration including a recess 31 and a protruding portion 32 extending from the recess 31. FIG. 6 shows the locking portion 3 of the second example in a state before the case 1 and the stator core 25 are fitted together, and FIG. 7 shows the locking portion 3 of the second example in a state after the case 1 and the stator core 25 are fitted together. FIG. 8 is a diagram for explaining the clearance between the protruding portion 32 and the case 1.

[0027] The locking portion 3 of the second example is formed with a recess 31 formed in a concave shape on the stator core outer peripheral surface 25b, and a protruding portion 32 protruding from the center of the recess 31 in the circumferential direction C to the radially outer side R1. That is, the locking portion 3 of the second example is provided with a first recess 31a, a second recess 31b, and a protruding portion 32 sandwiched between these two recesses 31 along the circumferential direction C. Here, as shown in FIG. 8, a portion of the stator core outer peripheral surface 25b other than the locking portion 3 is referred to as a general portion 4. The protruding portion 32 is formed to protrude radially outward R1 from the stator core outer peripheral surface 25b in the general portion 4. The difference in length in the radial direction R between the general portion 4 and the protruding portion 32 is referred to as a step D.

[0028] As in the first example, the case 1 and the stator core 25 are fixed by shrink fitting, for example, by heating the case 1 to expand it, and then housing the stator core 25 in the case cylindrical portion 11 of the case 1 (first step #1), and then cooling the case 1 to shrink it, thereby fitting the case 1 and the stator core 25 together (second step #2). As shown in FIG. 6, the case 1 is heated and expanded to the radially outward R1, and the stator core 25 is housed in the case 1 with the stator core outer peripheral surface 25b and the case inner peripheral surface 11a facing each other with a certain degree of clearance (first step #1). As shown in FIG. 8, the step D in the radial direction R between the locking portion 3 and the general portion 4 other than the locking portion 3 is set to be equal to or less than the expansion amount B of the case inner peripheral surface 11a to the radially outward R1 when the stator core 25 and the case 1 are fitted together by shrink fitting. Therefore, even if the protrusion 32 is formed to protrude radially outward R1 further than the stator core outer surface 25b in the general portion 4, the stator core 25 can be accommodated in the case 1 that has been heated and expanded radially outward R1.

[0029] When the expanded case 1 is cooled and contracts while the stator core 25 is housed in it, the stator core outer peripheral surface 25b of the general part 4 and the case inner peripheral surface 11a come into close contact with each other. At this time, in the locking part 3, the protruding part 32 protruding radially outward R1 from the stator core outer peripheral surface 25b of the general part 4 prevents the case 1 from contracting radially inward R2. Therefore, at the location corresponding to the protruding part 32, the case inner peripheral surface 11a is recessed radially outward R1 to form a recessed part 11d. That is, the protruding part 32 is in a state of being bitten into the case inner peripheral surface 11a (second step #2). By engaging the protruding part 32 with the recessed part 11d in this way, the relative movement between the stator core 25 and the case 1 in the circumferential direction C is restricted.

[0030] As in the first example, in the first recess 31a and the second recess 31b, the stator core outer peripheral surface 25b is recessed toward the radially inward R2, so that the case inner peripheral surface 11a may protrude toward the radially inward R2, forming a protruding portion 11p as in the first example. In this case, the protruding portion 11p and the first recess 31a, and the protruding portion 11p and the second recess 31b engage with each other, thereby restricting the relative movement between the stator core 25 and the case 1 in the circumferential direction C. For example, if the length of the first recess 31a and the second recess 31b in the circumferential direction C is increased, the protruding amount increases, and the protruding portion 11p is more likely to be formed.

[0031] 9 to 11 which illustrate a third example of the locking portion 3 having a protrusion 33. Fig. 9 shows the third example of the locking portion 3 before the case 1 and the stator core 25 are fitted together, and Fig. 10 shows the second example of the locking portion 3 after the case 1 and the stator core 25 are fitted together. Fig. 11 is a diagram for explaining the clearance between the protrusion 33 and the case 1.

[0032] The locking portion 3 of the third example is formed on the stator core outer peripheral surface 25b so as to protrude from the stator core outer peripheral surface 25b toward the radially outer side R1. That is, the locking portion 3 of the third example is formed with a protruding portion 33 formed in a protruding shape on the stator core outer peripheral surface 25b. In the third example, as in the second example, the portion of the stator core outer peripheral surface 25b other than the locking portion 3 is referred to as a general portion 4 (see FIG. 11). The protruding portion 33 is formed so as to protrude radially outward R1 from the stator core outer peripheral surface 25b in the general portion 4.

[0033] As in the first and second examples, the case 1 and the stator core 25 are fixed by shrink fitting, for example, by heating the case 1 to expand it, and then housing the stator core 25 in the case cylindrical portion 11 of the case 1 (first step #1), and then cooling the case 1 to contract it, so that the case 1 and the stator core 25 are fitted together. As shown in FIG. 9, the stator core 25 is housed in the case 1, which has been heated and expanded to the radially outward R1, with the stator core outer peripheral surface 25b facing the case inner peripheral surface 11a with a certain degree of clearance (first step #1). As shown in FIG. 11, the step D in the radial direction R between the locking portion 3 (protruding portion 33) and the general portion 4 other than the locking portion 3 is set to be equal to or less than the expansion amount B of the case inner peripheral surface 11a to the radially outward R1 when the stator core 25 and the case 1 are fitted together by shrink fitting. Therefore, even if the convex portion 33 is formed to protrude radially outward R1 further than the stator core outer surface 25b in the general portion 4, the stator core 25 can be accommodated in the case 1 that has been heated and expanded radially outward R1.

[0034] When the expanded case 1 is cooled and contracts while the stator core 25 is housed in it, the stator core outer peripheral surface 25b of the general part 4 and the case inner peripheral surface 11a come into close contact with each other. At this time, in the locking part 3, the convex part 33 protruding radially outward R1 from the stator core outer peripheral surface 25b of the general part 4 prevents the case 1 from contracting radially inward R2. As a result, the case inner peripheral surface 11a is recessed radially outward R1 at the location corresponding to the convex part 33 to form a recessed part 11d. That is, the convex part 33 is in a state of being bitten into the case inner peripheral surface 11a (second step #2). By engaging the convex part 33 with the recessed part 11d in this way, the relative movement between the stator core 25 and the case 1 in the circumferential direction C is restricted.

[0035] In the above, in the first, second and third examples, the locking portion 3 is provided on the stator core 25. However, although not shown in the drawings, the locking portion 3 may be provided on the case 1 side. That is, the locking portion 3 may be formed on the case inner circumferential surface 11a. In this case, the locking portion 3 may be formed to have a convex portion protruding from the case inner circumferential surface 11a toward the radially inward side R2, may be formed to have a concave portion recessed from the case inner circumferential surface 11a toward the radially outward side R1, or may be formed to have both a convex portion and a concave portion.

[0036] Furthermore, when a plurality of locking portions 3 are provided in the circumferential direction C, the locking portions 3 are not limited to being arranged at equal intervals as illustrated in FIG. 2, and may be arranged unevenly. If the locking portions 3 are arranged evenly at a plurality of locations in the circumferential direction C, they may resonate with the rotation of the rotor 21, generating audible noise. By arranging the plurality of locking portions 3 unevenly, the possibility of such resonance occurring can be reduced. Therefore, as illustrated in FIG. 12, the plurality of locking portions 3 may be arranged in the circumferential direction C such that the arrangement intervals P in the circumferential direction C are uneven.

[0037] As described above, according to the above embodiment, it is possible to provide a technique for fixing the case and the stator so as not to rotate relative to each other with a simpler structure.

[0038] [Overview of the embodiment] The above-described rotating electric machine (20) will now be briefly described.

[0039] In one embodiment, a rotating electric machine (20) comprises a stator core (25) arranged on the outside (R1) in the radial direction (R) with respect to a rotor (21), and a case (1) having an inner circumferential surface (11a) facing an outer circumferential surface (25b) of the stator core (25), the outer circumferential surface (25b) of the stator core (25) and the inner circumferential surface (11a) of the case (1) are fitted together in a tight fit, and a convex or concave engagement portion (3) is formed at least at one location in the circumferential direction (C) on either the outer circumferential surface (25b) of the stator core (25) or the inner circumferential surface (11a) of the case (1).

[0040] The boundary portion between the case (1) and the stator core (25) facing each other in the radial direction (R) is circular in the axial view along the rotation axis of the rotating electric machine (20). According to this configuration, the locking portion (3) is formed on either the outer peripheral surface (25b) of the stator core (25) or the inner peripheral surface (11a) of the case (1), and the outer peripheral surface (25b) of the stator core (25) and the inner peripheral surface (11a) of the case (1) are fitted together by an interference fit. Therefore, the locking portion (3) is pressed into the other of the outer peripheral surface (25b) of the stator core (25) and the inner peripheral surface (11a) of the case (1) by the pressure of the interference fit. This suppresses relative movement between the stator core (15) and the case (1) in the circumferential direction (C) at the circular boundary portion. The locking portion (3) is easily provided since it is sufficient to form the locking portion (3) on either the outer circumferential surface (25b) of the stator core (25) or the inner circumferential surface (11a) of the case (1). In this manner, with this configuration, the case (1) and the stator (24) can be fixed so as not to rotate relative to each other with a simpler structure.

[0041] It is also preferable that the locking portion (3) is provided on the outer circumferential surface (25b) of the stator core (25).

[0042] The stator core 25 is often formed by stacking punched steel plates in the axial direction (L). In this case, in order to form the locking portion 3 on the stator core 25, a die for punching the electromagnetic steel plates may be configured so that the punched steel plates have protrusions that will be stacked in the axial direction (L) to become the locking portion 3. This makes it possible to provide the locking portion 3 while minimizing increases in production costs.

[0043] In addition, it is preferable that the locking portion (3) is formed so as to be continuous over the entire area (A) in the axial direction (L) in the region where the outer peripheral surface (25b) of the stator core (25) and the inner peripheral surface (11a) of the case (1) face each other.

[0044] According to this configuration, the locking portions formed on either the outer circumferential surface of the stator core or the inner circumferential surface of the case are engaged with the other of the outer circumferential surface of the stator core or the inner circumferential surface of the case throughout the entire axial direction (L) of the region (A) where the stator core (25) and the case (1) face each other. This makes it possible to more firmly restrict relative movement between the stator core (25) and the case (1) in the circumferential direction.

[0045] In addition, it is preferable that the locking portion (3) is formed on the outer circumferential surface (25b) of the stator core (25) so as to protrude from the outer circumferential surface (25b) to the outside (R1) in the radial direction (R), and a step (D) in the radial direction (R) between the locking portion (3) and a general portion (4) other than the locking portion (3) is set to be equal to or less than an expansion amount (B) of the inner circumferential surface (11a) of the case (1) to the outside (R1) in the radial direction (R) when the stator core (25) and the case (1) are fitted together by shrink fitting.

[0046] According to this configuration, the locking portion (3) on the outer peripheral surface (25b) of the stator core (25) is provided so as to fit within the inner diameter of the case (1) that is heated and expanded during shrink fitting, so that the stator core (25) can be easily fitted inside the case (1) during shrink fitting. Furthermore, when the temperature of the case (1) drops and the case (1) contracts, the inner peripheral surface (11a) of the case (1) comes into contact with the locking portion (3), so that the relative movement between the stator core (25) and the case (1) can be appropriately restricted.

[0047] It is also preferable that the locking portions (3) are disposed at a plurality of locations in the circumferential direction (C).

[0048] When the locking portions (3) are formed at a plurality of locations in the circumferential direction (C), the relative movement between the stator core (25) and the case (1) can be more firmly restricted.

[0049] In addition, when the locking portions (3) are arranged at multiple locations in the circumferential direction (C), it is preferable that the locking portions (3) are arranged so that the arrangement intervals (P) in the circumferential direction (C) are uneven.

[0050] If the locking portions (3) are arranged at equal intervals (P) in the circumferential direction (C), the stator core and case will have shapes that tend to resonate at a specific resonant frequency, and therefore resonance may occur due to vibration caused by the rotation of the rotor (21). However, by unevenly arranging the multiple locking portions (3), it is possible to make it difficult for the stator core and case to resonate at a specific resonant frequency, thereby reducing the possibility of such resonance occurring.

[0051] In addition, it is preferable that the locking portion (3) is provided on the outer peripheral surface (25b) of the stator core (25), the case (1) has a target portion (5) whose strength in the radial direction (C) is weaker in the circumferential direction (C) than other portions (6), and the target portion (5) and the locking portion (3) overlap when viewed radially along the radial direction (R).

[0052] When the locking portion (3) is provided on the outer peripheral surface (25b) of the stator core (25), the case (1) is deformed in response to the locking portion (3) due to the pressure of the interference fit, so that the locking portion bites into the inner peripheral surface of the case. By providing the target portion (5) on the case (1) as in this configuration, it is possible to facilitate appropriate deformation of the case (1) in response to the locking portion (3), and therefore it is possible to more firmly restrict the relative movement between the stator core (25) and the case (1) in the circumferential direction (C).

[0053] In one embodiment, a method for manufacturing a rotating electric machine includes a stator core (25) and a case (1) having an inner circumferential surface (11a) facing an outer circumferential surface (25b) of the stator core (25), and the stator core (25) and the case (1) are fitted together such that the outer circumferential surface (25b) of the stator core (25) and the inner circumferential surface (11a) of the case (1) are tightly fitted together, with a convex or concave engagement portion (3) formed at at least one location in the circumferential direction (C) on either the outer circumferential surface (25b) of the stator core (25) or the inner circumferential surface (11a) of the case (1).

[0054] According to this manufacturing method, in a state where the locking portion (3) is formed on either the outer peripheral surface (25b) of the stator core (25) or the inner peripheral surface (11a) of the case (1) facing each other, the outer peripheral surface (25b) of the stator core (25) and the inner peripheral surface (11a) of the case (1) are fitted together so as to be in an interference fit state, so that the locking portion (3) is in a state of being bitten into the other of the outer peripheral surface (25b) of the stator core (25) or the inner peripheral surface (11a) of the case (1) due to the pressure of the interference fit. As a result, the stator core (25) and the case (1) are prevented from moving relative to each other in the circumferential direction (C) at a circular boundary portion that faces the case (1) and the stator core (25) in the radial direction (R) when viewed in the axial direction. The locking portion 3 only needs to be formed on either the outer circumferential surface 25b of the stator core 25 or the inner circumferential surface 11a of the case 1, so that it is easy to provide the locking portion 3. In this manner, according to the present manufacturing method, the case 1 and the stator 24 can be fixed so as not to rotate relative to each other with a simpler structure.

[0055] In addition, in the manufacturing method of a rotating electric machine, the locking portion (3) is formed on the outer peripheral surface (25b) of the stator core (25) so as to protrude from the outer peripheral surface (25b) to the outside (R1) in the radial direction (R), and the stator core (25) and the case (1) are fitted together by shrink fitting while the case (1) is heated so that an amount of expansion (B) of the inner peripheral surface (11a) of the case (1) to the outside (R1) in the radial direction (R) is larger than a step (D) in the radial direction (R) between the locking portion (3) and a general portion (4) other than the locking portion (3).

[0056] According to this manufacturing method, the stator core (25) having the locking portion (3) formed on the outer circumferential surface (25b) can be fitted into the inner diameter of the case (1) expanded by heating (#1). When the case (1) subsequently cools and contracts, the inner circumferential surface (11a) of the case (1) comes into contact with the locking portion (3), and the locking portion (3) is pressed into the inner circumferential surface (11a) of the case (1) by the pressure. That is, according to this manufacturing method, the case (1) and the stator (24) can be fixed by shrink fitting so that they do not rotate relative to each other. [Explanation of symbols]

[0057] 1: Case 3: Locking part 4: General section 5: Target area 11a: Case inner surface (inner surface of case) 20: Rotating electric machine 21: Rotor 25: Stator core 25b: Stator core outer surface (outer surface of stator core) A: Axial facing area (area where the outer circumferential surface of the stator core faces the inner circumferential surface of the case) (Full axial range in B: Amount of expansion C: Circumferential direction D: Step L: Axial direction P: Placement interval R: Radial direction R1: Radial outer side (radial outer side) R2: Radial inner side (radial inner side)

Claims

1. A rotating electric machine mounted on a vehicle to serve as a driving force source for wheels, a stator core disposed radially outward of the rotor; a case having an inner circumferential surface facing an outer circumferential surface of the stator core; an outer case disposed radially outward relative to the case; the outer circumferential surface of the stator core and the inner circumferential surface of the case are fitted together in an interference fit state; A recessed locking portion is formed at least at one location in a circumferential direction on the outer circumferential surface of the stator core, a refrigerant flow path through which a refrigerant flows is provided between the case and the outer case so as to be covered by the outer case; A portion of the case where the refrigerant flow path is formed is more likely to deform in the radial direction than other portions, The rotating electric machine, wherein the engaging portion and the refrigerant flow path overlap each other when viewed in the radial direction.

2. The rotating electric machine according to claim 1 , wherein a portion of the outer circumferential surface of the stator core other than the locking portion is in close contact with the inner circumferential surface of the case.

3. 3 . The rotating electric machine according to claim 1 , wherein the locking portion is formed so as to be continuous over an entire area in the axial direction in which the outer circumferential surface of the stator core and the inner circumferential surface of the case face each other.

4. The rotating electric machine according to claim 1 , wherein the locking portions are arranged at a plurality of positions in the circumferential direction.

5. The rotating electric machine according to claim 4 , wherein the locking portions are arranged at uneven intervals in the circumferential direction.

6. The rotating electric machine according to claim 1 , wherein the coolant flow passage is formed in a portion of the circumferential direction.

7. A method for manufacturing a rotating electric machine comprising: a stator core; a case having an inner circumferential surface facing an outer circumferential surface of the stator core; and an outer case disposed radially outward of the stator core relative to the case, the rotating electric machine being mounted on a vehicle and serving as a driving force source for wheels, the method comprising the steps of: The case is provided with a portion in which a coolant flow path through which a coolant flows is formed, and the portion is more easily deformed in the radial direction than other portions, A recessed locking portion is formed at least at one location in a circumferential direction on the outer circumferential surface of the stator core, A manufacturing method for a rotating electric machine, comprising: providing a refrigerant flow path between the case and the outer case so as to be covered by the outer case; engaging the stator core and the case so that the engagement portion and the refrigerant flow path overlap when viewed radially along the radial direction; and fitting the outer peripheral surface of the stator core and the inner peripheral surface of the case together in a tight fit.

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