JP7658482B2 - Rotating electric machine and method for manufacturing the same - Google Patents

Description

The present invention relates to a rotating electric machine having 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.

JP 2015-34754 A discloses a rotating electric machine (MG) equipped with a key structure (key engagement portion (30)) for restricting the 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 protrusion (31) that protrudes 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) that faces the outer circumferential surface of the stator (11) so as to retract radially outward. The key groove (32) and the key protrusion (31) engage with each other to restrict the circumferential movement of the stator (11) relative to the case (101).

JP 2015-34754 A

When providing a key structure as described above, machining costs are incurred for both the case and the stator, which may increase the production costs of the rotating electric machine. In addition, a clearance is required between the key groove and the key protrusion, and within the range of this clearance, the case and stator rotate slightly relative to each other. This relative rotation may cause vibrations and noise.

Therefore, there is a need for a technology that uses a simpler structure to fix the case and stator so that they do not rotate relative to each other.

In view of the above problems, the rotating electric machine according to the present invention comprises a stator core arranged radially outward from a rotor, and a case having an inner peripheral surface facing the outer peripheral surface of the stator core, the outer peripheral surface of the stator core and the inner peripheral surface of the case being fitted together in a tight fit, and a convex or concave locking portion is formed at at least one location in the circumferential direction on either the outer peripheral surface of the stator core or the inner peripheral surface of the case.

The boundary portion between the case and the stator core facing each other in the radial direction is circular when viewed in the axial direction along 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 prevents the stator core and the case from moving relative to each other 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.

In view of the above problems, the present invention provides a method for manufacturing a rotating electric machine that includes a stator core and a case having an inner peripheral surface that faces the outer peripheral surface of the stator core, and the stator core and the case are fitted together such that the outer peripheral surface of the stator core and the inner peripheral surface of the case are tightly fitted together, with a convex or concave locking portion formed at least at one location in the circumferential direction on either the outer peripheral surface of the stator core or the inner peripheral surface of the case.

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 bites into the other of the outer peripheral surface of the stator core or the inner peripheral surface of the case due to the pressure of the tight fit. This prevents the stator core and the case from moving relative to each other 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 that they do not rotate relative to each other with a simpler structure.

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, which are explained with reference to the drawings.

FIG. 1 is an axial cross-sectional view showing an example of a rotating electric machine. FIG. 1 is a radial cross-sectional view showing an example of a rotating electric machine; 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; FIG. 13 is a diagram showing a first example of a locking portion after the case and the stator core are fitted together; FIG. 13 is a diagram showing a first example of a locking portion in a state where a case having a target portion is fitted to a stator core; 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; FIG. 13 is a diagram showing a second example of the locking portion after the case and the stator core are fitted together; 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. 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; FIG. 13 is a diagram showing a third example of the locking portion after the case and the stator core are fitted together; 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. FIG. 13 is a radial cross-sectional view showing another example of a rotating electric machine;

The following describes an embodiment of the rotating electric machine with reference to the drawings. FIG. 1 is an axial cross-sectional view showing an example of a vehicle drive device 100 equipped with 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 the wheels. In the following description, when the term "cylindrical" or "cylindrical" is used, it means that the overall general shape is a tube or cylinder even if it has some irregular parts. This is not limited to these, and the same applies to other expressions that use "shape" to describe the 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.

The rotating electric machine 20 is a permanent magnet type rotating electric machine including a rotor 21 with a permanent magnet 23 inside a rotor core 22, a stator 24 with 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 radial outside 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 radial inside R2 of the rotor core 22, and the rotor 21 and the rotor shaft 27 rotate together. In this embodiment, the rotating electric machine 20 is a permanent magnet type rotating electric machine, but it may be another type of rotating electric machine, such as an induction type rotating electric machine.

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 arranged on the radial outside R1 of the case 1. The case 1 may be referred to as the inner case, and the water jacket 2 and the outer case. As shown in FIG. 1, the stator core 25 is arranged on the radial outside R1 relative to the rotor 21. The case 1 includes a case cylindrical portion 11 having a peripheral wall portion, and the inner peripheral surface of the case cylindrical portion 11 that faces the stator core outer peripheral surface 25b, which is the outer peripheral surface of the stator core 25, is referred to as the 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.

1, the groove 15 is formed on the outer circumferential surface 11b of the case tubular portion 11 so as to have a portion that abuts against the inner circumferential surface 12a of the jacket tubular portion 12 of the water jacket 2 and a portion that is spaced apart from the inner circumferential surface 12a. As a result, a refrigerant flow path 16 is formed between the case tubular portion 11 and the jacket tubular portion 12, through which the refrigerant flows along the axial direction L. As shown in FIG. 2, a plurality of grooves 15 are formed in the circumferential direction C of the case outer circumferential surface 11b. As described above, the stator 24 is fixed to the case 1 with the stator core outer circumferential surface 25b abutting against the inner circumferential surface 11a of the case tubular 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 tubular portion 11 and the jacket tubular portion 12 is increased, and the stator 24 can be efficiently cooled.

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 in a state of being 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.

The locking portion 3 may be formed at least at one location in the circumferential direction C, but as shown in FIG. 2, it is preferable to provide the locking portion 3 at multiple locations in the circumferential direction C. When the locking portion 3 is 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.

As shown in FIG. 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 multiple core plates, which are formed by punching electromagnetic steel sheets, in the axial direction L. Therefore, in order to form the locking portion 3 on the stator core 25, a die for punching the electromagnetic steel sheets can be configured so that protrusions that become the locking portions 3 are formed on the core plates by stacking them in the axial direction L. Therefore, the locking portion 3 can be provided on the stator core 25 while minimizing increases in production costs.

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 area in the axial direction L in which the locking portion 3 is biting into the case inner peripheral surface 11a becomes larger, 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 area in the axial direction L in the area where the stator core outer peripheral surface 25b and the case inner peripheral surface 11a face each other (axial facing area 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 area of the axial facing area 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.

Below, a first example of the locking portion 3 will be described with reference to Figs. 3 to 5, which illustrate a 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 explaining the target portion 5 (described later) in a state after the case 1 and the stator core 25 are fitted together.

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. 3, which shows one state in the first step #1, the case 1 is heated and expanded radially outward R1, and the stator core 25 is housed in the case 1 with a certain amount of clearance between the stator core outer peripheral surface 25b and the case inner peripheral surface 11a.

4 shows a state in which the stator core 25 is housed in the heated case 1, the case 1 is cooled and contracted, and the stator core outer peripheral surface 25b and the case inner peripheral surface 11a are in close contact with each other (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 R2, so that the case inner peripheral surface 11a protrudes toward the radially inward R2 to form a protruding portion 11p.
The recess 31 and the protruding portion 11p engage with each other, thereby restricting relative movement between the stator core 25 and the case 1 in the circumferential direction C.

1 and 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 outer peripheral surface 25b of the stator core and the case 1 has a target portion 5 whose strength in the radial direction R is weaker than other portions (non-target portion 6) in the circumferential direction C, as shown in FIG. 2 and FIG. 5, if the target portion 5 and the locking portion 3 overlap in the radial direction R, the protruding portion 11p described above is more likely to be formed. The same applies to the recessed portion 11d in the second and third examples described below (see Figures 7 and 10).

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 shrink fitting or other tight fitting as described above, the case 1 side deforms in response to the locking portion 3. By providing a 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 protrusion portion 11p (see Figures 4 and 5) and the recessed portion 11d (see Figures 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.

2 illustrates an example in which all of the locking portions 3 formed at multiple locations overlap the groove portion 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 portion 15 that becomes the target portion 5 may be formed in a location that does not overlap the locking portion 3 in a radial view. In addition, in this embodiment, the groove portion 15 for forming the refrigerant flow path 16 is illustrated as 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 path 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 a non-target portion 6.

A second example of the locking portion 3 will be described below with reference to Figs. 6 to 8, which illustrate a configuration including a recess 31 and a protrusion 32 extending from the recess 31. Fig. 6 shows the second example of the locking portion 3 before the case 1 and the stator core 25 are fitted together, and Fig. 7 shows the second example of the locking portion 3 after the case 1 and the stator core 25 are fitted together. Fig. 8 is a diagram explaining the clearance between the protrusion 32 and the case 1.

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 formed 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, the portion of the stator core outer peripheral surface 25b other than the locking portion 3 is referred to as the 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 the step D.

As in the first example, the case 1 and the stator core 25 are fixed by shrink fitting, for example, by heating and expanding the case 1, and then accommodating the stator core 25 in the case cylindrical portion 11 of the case 1 (first step #1), and then cooling and shrinking the case 1 in this state to fit the case 1 and the stator core 25 together (second step #2). As shown in FIG. 6, the case 1 is heated and expanded radially outward R1, and the stator core 25 is accommodated in the case 1 with a certain degree of clearance between the stator core outer peripheral surface 25b and the case inner peripheral surface 11a (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 amount of expansion B of the case inner peripheral surface 11a in the radial 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 from the outer circumferential surface 25b of the stator core in the general portion 4, the stator core 25 can be housed in the case 1 that is heated and expanded radially outward R1.

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

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 relative movement of the stator core 25 and the case 1 in the circumferential direction C is restricted by the engagement of the protruding portion 11p with the first recess 31a and the protruding portion 11p with the second recess 31b. For example, if the length of the first recess 31a and the second recess 31b in the circumferential direction C is increased, the amount of protrusion increases, making it easier to form the protruding portion 11p.

The following description will also refer to Figs. 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 explaining the clearance between the protrusion 33 and the case 1.

The locking portion 3 in the third example is formed on the stator core outer peripheral surface 25b so as to protrude radially outward R1 from the stator core outer peripheral surface 25b. In other words, the locking portion 3 in the third example is formed with a protruding portion 33 formed in a convex 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 the 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.

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 accommodating 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 to fit the case 1 and the stator core 25 together (second step #2). As shown in FIG. 9, the case 1 is heated and expanded radially outward R1, and the stator core 25 is accommodated in the case 1 with a certain degree of clearance between the stator core outer peripheral surface 25b and the case inner peripheral surface 11a (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 amount of expansion B of the case inner peripheral surface 11a to the radial outward R1 when the stator core 25 and the case 1 are fitted together by shrink fitting. Therefore, even if the protrusions 33 are formed to protrude radially outward R1 from the outer circumferential surface 25b of the stator core in the general portion 4, the stator core 25 can be housed in the case 1 that has been heated and expanded radially outward R1.

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

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 that protrudes from the case inner circumferential surface 11a to the radially inward side R2, may be formed to have a concave portion that recesses from the case inner circumferential surface 11a to the radially outward side R1, or may be formed to have both a convex portion and a concave portion.

In addition, when multiple 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 multiple locations in the circumferential direction C, they may resonate with the rotation of the rotor 21, generating audible noise. By arranging the multiple locking portions 3 unevenly, the possibility of such resonance occurring can be reduced. Therefore, as illustrated in FIG. 12, multiple locking portions 3 may be arranged in the circumferential direction C so that the arrangement intervals P in the circumferential direction C are uneven.

As explained above, the above-mentioned embodiment provides a technology that uses a simpler structure to fix the case and the stator so that they do not rotate relative to each other.

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

In one embodiment, the rotating electric machine (20) comprises a stator core (25) disposed on the outer side (R1) of the rotor (21) in the radial direction (R), and a case (1) having an inner peripheral surface (11a) facing the outer peripheral surface (25b) of the stator core (25). The outer peripheral surface (25b) of the stator core (25) and the inner peripheral surface (11a) of the case (1) are fitted together in a tight fit, and a convex or concave locking portion (3) is formed at least at one location in the circumferential direction (C) on either the outer peripheral surface (25b) of the stator core (25) or the inner peripheral surface (11a) of the case (1).

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 seen in the direction along the rotation axis of the rotating electric machine (20). According to this configuration, a 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, 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) and the inner peripheral surface (11a) of the case (1) by the pressure of the interference fit. This suppresses the relative movement of the stator core (15) and the case (1) in the circumferential direction (C) at the circular boundary portion. This locking portion (3) only needs to be formed on either the outer peripheral surface (25b) of the stator core (25) or the inner peripheral surface (11a) of the case (1), so it is easy to provide the locking portion. In this way, with this configuration, the case (1) and the stator (24) can be fixed so that they do not rotate relative to each other with a simpler structure.

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

The stator core (25) is often formed by stacking punched steel plates in the axial direction (L). In this case, to form the locking portion (3) on the stator core (25), a die for punching the electromagnetic steel plate is configured so that the punched steel plate has a protrusion that will be stacked in the axial direction (L) and become the locking portion (3). Therefore, the locking portion (3) can be provided while minimizing the increase in production costs.

It is also 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.

According to this configuration, in the entire axial direction (L) of the region (A) where the stator core (25) and the case (1) face each other, the locking portion formed on either the outer peripheral surface of the stator core or the inner peripheral surface of the case is engaged with the other of the outer peripheral surface of the stator core or the inner peripheral surface of the case. Therefore, the relative movement in the circumferential direction between the stator core (25) and the case (1) can be more firmly restricted.

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 step (D) in the radial direction (R) between the locking portion (3) and the general portion (4) other than the locking portion (3) is preferably set to be equal to or less than the amount of expansion (B) of the inner peripheral 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.

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. In addition, 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.

It is also preferable that the locking portions (3) are arranged at multiple locations in the circumferential direction (C).

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

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 unequal.

If the locking parts (3) are spaced apart (P) in the circumferential direction (C), the stator core and case will have shapes that tend to resonate at a specific resonant frequency, and there is a possibility that resonance will occur due to vibrations caused by the rotation of the rotor (21). However, by arranging the multiple locking parts (3) unevenly, 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.

Furthermore, 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 than other portions (6) in the circumferential direction (C), and the target portion (5) and the locking portion (3) overlap when viewed radially along the radial direction (R).

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 tight 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 make it easier to deform the case (1) appropriately 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).

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

According to this manufacturing method, the outer peripheral surface (25b) of the stator core (25) and the inner peripheral surface (11a) of the case (1) are fitted together 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, so that the locking portion (3) is pressed into either the outer peripheral surface (25b) of the stator core (25) or the inner peripheral surface (11a) of the case (1) by the pressure of the pressurized 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 facing the case (1) and the stator core (25) in the radial direction (R) when viewed in the axial direction. This locking portion (3) only needs to be formed on either the outer peripheral surface (25b) of the stator core (25) or the inner peripheral surface (11a) of the case (1), so it is easy to provide the locking portion (3). In this way, with this manufacturing method, the case (1) and the stator (24) can be fixed so that they do not rotate relative to each other with a simpler structure.

In addition, the manufacturing method of the rotating electric machine is preferably such that 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 the amount of expansion (B) of the inner peripheral surface (11a) of the case (1) to the outside (R1) in the radial direction (R) is greater than the step (D) in the radial direction (R) between the locking portion (3) and the general portion (4) other than the locking portion (3).

According to this manufacturing method, the stator core (25) with the locking portion (3) formed on the outer peripheral surface (25b) can be fitted into the inner diameter of the case (1) that has expanded due to heating (#1). When the case (1) subsequently cools and contracts, the inner peripheral surface (11a) of the case (1) comes into contact with the locking portion (3), and the locking portion (3) is forced into the inner peripheral surface (11a) of the case (1) by the pressure. In other words, 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.

1: Case 3: Locking portion 4: General portion 5: Target portion 11a: Case inner peripheral surface (inner peripheral surface of the case)
20: Rotating electric machine 21: Rotor 25: Stator core 25b: Stator core outer circumferential surface (outer circumferential surface of stator core)
A: Axial facing region (the entire axial region where the outer peripheral surface of the stator core and the inner peripheral surface of the case face each other)
B: Amount of expansion C: Circumferential direction D: Step L: Axial direction P: Arrangement interval R: Radial direction R1: Radial outer side (radial outer side)
R2: Radial inner side (radial inner side)

Claims (7)

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. The rotating electric machine according to claim 1, wherein the outer peripheral surface of the stator core is in close contact with the inner peripheral surface of the case, except for the locking portion. The rotating electric machine according to claim 1 or 2, wherein the locking portion is formed so as to be continuous over the entire axial area in the region where the outer peripheral surface of the stator core and the inner peripheral surface of the case face each other. The rotating electric machine according to any one of claims 1 to 3, wherein the locking portions are arranged at multiple locations in the circumferential direction. The rotating electric machine according to claim 4, wherein the locking portions are arranged so that the spacing between the locking portions is uneven in the circumferential direction. The rotating electric machine according to claim 1 , wherein the coolant flow passage is formed in a portion of the circumferential direction. 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.

Images