Stator and electric motor equipped with it

Abstract

To provide a technique that can obtain both cooling performance and electromagnetic characteristics of a stator.SOLUTION: A stator includes: a core back that extends cylindrically along an axial direction; a plurality of teeth provided on an inner surface of the core back; and a stator coil provided at the plurality of teeth. In a part of a circumferential direction of the core back, a plurality of refrigerant flow channels extending along the axial direction to a first end surface of the core back is arranged along the circumferential direction. The plurality of refrigerant flow channels include a refrigerant flow channel located at the uppermost position in a vertical direction of the core back and a refrigerant flow channel located at the lowermost position in the vertical direction of the core back. At the first end face of the core back, the arrangement of the plurality of refrigerant flow channels has twofold symmetry and does not have fourfold symmetry.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technology disclosed in the present specification relates to a stator and an electric motor including the same.

[0002] Patent Document 1 describes a stator for an electric motor. The stator includes a core back extending cylindrically along the axial direction, a plurality of teeth provided on an inner circumferential surface of the core back, and stator coils provided on the plurality of teeth. In the core back, a plurality of refrigerant flow paths extending along the axial direction to an end surface of the core back are arranged along the circumferential direction. The refrigerant flowing through the refrigerant flow paths is supplied from the end surface of the core back to a coil end of the stator coil.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] In the stator described above, the plurality of refrigerant flow paths are provided over the entire circumference of the core back. With such a configuration, although excellent cooling performance is achieved, there is a problem that the iron loss of the stator is increased. In order to reduce the iron loss of the stator, it is conceivable to eliminate some of the plurality of refrigerant flow paths. However, eliminating some of the plurality of refrigerant flow paths may lead to insufficient cooling performance or deterioration of the electromagnetic characteristics of the stator. In view of these circumstances, the present specification provides a technology that can achieve both the cooling performance and electromagnetic characteristics of a stator.

Means for Solving the Problem

[0005] The technology disclosed herein is embodied in a stator for an electric motor. In a first embodiment of the technology, the stator comprises a core back extending cylindrically along the axial direction, a plurality of teeth provided on the inner circumferential surface of the core back, and stator coils provided on the plurality of teeth. Within a portion of the circumferential region of the core back, a plurality of refrigerant passages are arranged along the circumferential direction, extending along the axial direction to a first end face of the core back. The plurality of refrigerant passages include a refrigerant passage located at the uppermost part of the core back in the vertical direction and a refrigerant passage located at the lowermost part of the core back in the vertical direction. At the first end face of the core back, the arrangement of the plurality of refrigerant passages has twofold symmetry but not fourfold symmetry.

[0006] In the stator according to this technology, multiple refrigerant passages are provided in the core back. These multiple refrigerant passages extend axially to the first end face of the core back. The refrigerant flowing through the refrigerant passages is supplied from the first end face of the core back to the first coil end. This cools the first coil end with the refrigerant. The first coil end is one end of the stator coil that protrudes from the first end face of the core back. In the stator according to this technology, the multiple refrigerant passages are provided only in a limited area in the circumferential direction of the core back. Compared to conventional structures, the iron loss of the stator is reduced by reducing a portion of the multiple refrigerant passages.

[0007] However, reducing some of the multiple refrigerant flow paths may result in insufficient cooling of the first coil end. In this regard, the configuration of this technology provides at least one refrigerant flow path at both the uppermost and lowermost points of the core back in the vertical direction. With this configuration, refrigerant can be effectively supplied to the first coil end. That is, the refrigerant supplied to the first coil end from the refrigerant flow path flows downward due to its own weight, cooling the first coil end. Therefore, by providing a refrigerant flow path at the uppermost point of the core back, refrigerant can be supplied to the uppermost point of the first coil end, allowing the refrigerant to reach the entire coil end. However, at the lowermost point of the first coil end, the temperature of the refrigerant has already risen, so there is a risk that the amount of heat absorbed by the refrigerant will be insufficient. Therefore, by also providing a refrigerant flow path at the lowermost point of the core back and directly supplying refrigerant to the lowermost point of the first coil end, cooling at the lowermost point of the first coil end can be promoted.

[0008] Furthermore, reducing some of the multiple refrigerant flow paths may degrade the electromagnetic characteristics of the stator. In this regard, the stator according to this technology has a twofold symmetry in the arrangement of the multiple refrigerant flow paths, but not a fourfold symmetry. In other words, compared to conventional structures, the removal of some of the multiple refrigerant flow paths results in the loss of fourfold symmetry, but the maintenance of twofold symmetry. Maintaining twofold symmetry ensures that the arrangement of the multiple refrigerant flow paths maintains symmetry in at least two orthogonal directions (e.g., vertical and horizontal directions). This maintains the symmetry of the electromagnetic characteristics required for the stator, thus avoiding the induction of vibrations in the rotor, for example. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing the configuration of the electric motor 2 in the embodiment. [Figure 2] This is a cross-sectional view along line II-II in Figure 1. [Figure 3] This is a cross-sectional view along the line III-III in Figure 1. [Figure 4] This is a cross-sectional view along the line IV-IV in Figure 1. However, details of the teeth 14 and stator coil 16 are omitted from the illustration. [Figure 5] This is a partial cross-sectional view showing the stator cores 12 and 14 individually. [Figure 6] Figure 2 is a corresponding cross-sectional view showing the features of the electric motor 102 of another embodiment. [Figure 7] Figure 2 is a cross-sectional view corresponding to Figure 2, showing the features of the electric motor 202 of another embodiment. [Modes for carrying out the invention]

[0010] In a second aspect of this technology, in addition to the first aspect described above, the plurality of refrigerant flow paths may include a plurality of first refrigerant flow paths provided in a first range in the circumferential direction of the core back, and a plurality of second refrigerant flow paths provided in a second range in the circumferential direction of the core back. In this case, the first range may include the uppermost part, and the second range may include the lowermost part.

[0011] In a third aspect of this technology, in addition to the second aspect described above, the uppermost part may be located in the center of the first range, and the lowermost part may be located in the center of the second range. In this case, the first range and the second range each extend symmetrically in the horizontal direction.

[0012] In a fourth aspect of this technology, in addition to the second or third aspect described above, the first range and the second range may each be an angular range of 120 degrees or less in the circumferential direction.

[0013] In a fifth aspect of this technology, in addition to the fourth aspect described above, the first range and the second range may each be an angular range of 45 degrees or less in the circumferential direction.

[0014] In a sixth aspect of this technology, in addition to any of the second to fifth aspects described above, the plurality of refrigerant flow paths may not be present in the third and fourth circumferential ranges of the core back, which are adjacent to the first and second ranges, respectively.

[0015] In a seventh aspect of this technology, in addition to any of the first to sixth aspects described above, at least a portion of the plurality of refrigerant flow paths may be composed of a plurality of through holes defined within the core back. However, in another embodiment, at least a portion of the plurality of refrigerant flow paths may be composed of a plurality of grooves defined on the outer circumferential surface of the core back.

[0016] In an eighth aspect of this technology, in addition to any of the first to seventh aspects described above, the core back may further be provided with an annular refrigerant flow path that extends in the circumferential direction and is connected to each of the plurality of refrigerant flow paths. With this configuration, refrigerant can be circulated from the annular refrigerant flow path to each of the plurality of refrigerant flow paths.

[0017] In a ninth aspect of this technology, in addition to the eighth aspect described above, the annular refrigerant flow path may be formed by grooves defined on the outer circumferential surface of the core back.

[0018] In a tenth aspect of this technology, in addition to the eighth or ninth aspect described above, the stator may further include a casing surrounding the outer circumferential surface of the core back. In this case, the casing may have a refrigerant supply hole connected to the annular refrigerant flow path, located at an intermediate position in the vertical direction. With this configuration, the refrigerant supplied from the refrigerant supply hole to the annular refrigerant flow path is divided vertically along the annular refrigerant flow path, thereby efficiently supplying refrigerant to each of the multiple refrigerant flow paths.

[0019] In an eleventh aspect of the present technology, in addition to any one of the first to tenth aspects described above, the stator may further comprise a first annular member provided on the first end face of the core back. In this case, the first annular member may have a plurality of first refrigerant injection holes oriented toward a first coil end of the stator coil protruding from the first end face. According to such a configuration, refrigerant from the plurality of refrigerant flow paths can be injected toward the first coil end.

[0020] In a twelfth aspect of the present technology, in addition to any one of the first to eleventh aspects described above, the plurality of refrigerant flow paths may extend along the axial direction to a second end face located on a side opposite to the first end face of the core back. According to such a configuration, refrigerant can also be supplied to a second coil end of the stator coil protruding from the second end face of the core back.

[0021] In a thirteenth aspect of the present technology, in addition to the twelfth aspect described above, the stator may further comprise a second annular member provided on the second end face of the core back. In this case, the second annular member may have a plurality of second refrigerant injection holes oriented toward the second coil end of the stator coil protruding from the second end face. According to such a configuration, refrigerant from the plurality of refrigerant flow paths can be injected toward the second coil end.

[0022] The technology disclosed in the present specification is also embodied in an electric motor. In a fourteenth aspect of the present technology, the electric motor may comprise a stator and a rotor disposed inside the stator. In this case, the stator may be the stator according to any one of the first to thirteenth aspects described above.

[0023] Hereinafter, representative and non-limiting specific examples of the present invention will be described in detail with reference to the drawings. This detailed description is simply intended to show those skilled in the art details for carrying out preferred examples of the present invention and is not intended to limit the scope of the present invention. Furthermore, additional features and inventions disclosed below may be used separately from or in conjunction with other features and inventions to provide further improved stators and electric motors equipped therewith.

[0024] Furthermore, the combinations of features and processes disclosed in the following detailed description are not essential for carrying out the present invention in the broadest sense, and are described solely to illustrate representative examples of the present invention. Moreover, the various features of the representative examples described above and below, as well as the various features described in the independent and dependent claims, do not necessarily have to be combined in the same way as the examples described herein or in the order listed, in order to provide additional and useful embodiments of the present invention.

[0025] All features described herein and / or in the claims are intended to be disclosed individually and independently of each other, as limitations to the original disclosure and claimed specific subject matter, separate from the features described in the examples and / or claims. Furthermore, all descriptions of numerical ranges and groups or clusters are intended to disclose intermediate configurations as limitations to the original disclosure and claimed specific subject matter. [Examples]

[0026] Referring to the drawings, the stator 10 of the embodiment and the electric motor 2 equipped with the stator 10 will be described. Although not particularly limited, the electric motor 2 can be used in an electric vehicle as a prime mover for driving wheels. Here, an electric vehicle broadly means a vehicle having a motor that drives at least one wheel, and includes, for example, battery electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and fuel cell electric vehicles.

[0027] Here, directions X and Y in the drawing are both horizontal and perpendicular to each other. Direction Z in the drawing is vertical and perpendicular to directions X and Y. Direction X is parallel to the central axis C of the electric motor 2 and may be referred to as axial direction X in this specification. Direction R in the drawing indicates the circumferential direction R centered on the central axis C of the electric motor 2. The unsymmetrized arrows in the drawing schematically indicate the flow of the refrigerant.

[0028] As shown in Figures 1-5, the electric motor 2 comprises a rotor 4 and a stator 10. The rotor 4 is located within the stator 10 and is rotatably supported about a central axis C. The rotor 4 comprises a central shaft 6 and a rotor core 8 fixed to the central shaft 6. The rotor core 8 is constructed using a soft magnetic material. In this embodiment, the rotor core 8 has a structure in which multiple electromagnetic steel sheets are laminated. In addition, multiple permanent magnets (not shown) are provided on the rotor core 8 along the circumferential direction R.

[0029] The stator 10 comprises stator cores 12 and 14, stator coils 16, and a casing 18. The stator cores 12 and 14 are constructed using a soft magnetic material. In this embodiment, the stator cores 12 and 14 have a structure in which multiple electromagnetic steel sheets are laminated. The stator cores 12 and 14 have a core back 12 that extends cylindrically along the axial direction X, and a plurality of teeth 14 provided on the inner circumferential surface 12a of the core back 12. The plurality of teeth 14 are arranged at equal intervals along the circumferential direction R. Each of the plurality of teeth 14 protrudes from the inner circumferential surface 12a of the core back 12 toward the central axis C. Note that in some drawings, some or all of the plurality of teeth 14 are omitted from the illustration. The casing 18 is arranged to surround the outer circumferential surface 12b of the core back 12.

[0030] The stator coil 16 is provided on a plurality of teeth 14. Although detailed illustrations are omitted, the stator coil 16 is an assembly of a plurality of coils, each of which is arranged to surround one or more corresponding teeth 14. The stator coil 16 may be made of flexible wire or of rigid flat wire. The specific configuration of the stator coil 16 is not particularly limited. Both ends 16a and 16b of the stator coil 16 in the axial direction X protrude from the stator cores 12 and 14. In this specification, one end 16a of the stator coil 16 in the axial direction X is referred to as the first coil end 16a, and the other end 16b of the stator coil 16 in the axial direction X is referred to as the second coil end 16b.

[0031] The core bag 12 is provided with a plurality of refrigerant passages 30. The plurality of refrigerant passages 30 are arranged along the circumferential direction R at a position close to the outer peripheral surface 12b of the core bag 12. Each of the plurality of refrigerant passages 30 extends along the axial direction X and reaches the first end face 12c and the second end face 12d of the core bag 12 in the axial direction. The specific configuration of the plurality of refrigerant passages 30 is not particularly limited. For example, the cross-sectional shape of each refrigerant passage 30 may be rectangular, circular, or other shapes. Also, the plurality of refrigerant passages 30 may be arranged in two or more rows along the circumferential direction R. The plurality of refrigerant passages 30 are passages for circulating refrigerant. The refrigerant referred to here is a heat transfer medium intended for cooling, and in particular is a liquid oil.

[0032] The multiple refrigerant flow paths 30 are provided only in certain ranges A1 and A2 in the circumferential R of the core back 12. Specifically, the multiple refrigerant flow paths 30 include a plurality of first refrigerant flow paths 32 provided in a first range A1 in the circumferential R of the core back 12, and a plurality of second refrigerant flow paths 34 provided in a second range A2 in the circumferential R of the core back 12. The first range A1 includes the uppermost part 12UM in the vertical direction of the core back 12, and the second range A2 includes the lowermost part 12LM in the vertical direction of the core back 12. On the other hand, the multiple refrigerant flow paths 30 are not provided in the third range A3 and fourth range A4 in the circumferential R of the core back 12. The third range A3 and the fourth range A4 are ranges located between the first range A1 and the second range A2, and are adjacent to the first range A1 and the second range A2. The third range A3 and the fourth range A4 are opposite each other in the horizontal direction, with the central axis C in between.

[0033] The first range A1 and the second range A2 described above have equal angular ranges in the circumferential direction R and are symmetrical with respect to the central axis C. As a result, the arrangement of the multiple refrigerant flow paths 30 at the first end face 12c of the core back 12 has twofold symmetry but does not have fourfold symmetry (see Figure 2). Similarly, as shown in Figure 3, the arrangement of the multiple refrigerant flow paths 30 at the second end face 12d of the core back 12 has twofold symmetry but does not have fourfold symmetry (see Figure 3).

[0034] For example, each of the first range A1 and the second range A2 may have an angular range of 120 degrees or less. Alternatively, each of the first range A1 and the second range A2 may have an angular range of 90 degrees or less. Alternatively, each of the first range A1 and the second range A2 may have an angular range of 45 degrees or less. For example, in Figure 1, the first range A1 and the second range A2 each have an angular range of 120 degrees in the circumferential direction R.

[0035] For example, the first range A1 may be a range centered on the uppermost part 12UM of the core back 12. That is, the uppermost part 12UM may be located in the center of the first range A1, and the first range A1 may extend horizontally symmetrically from the uppermost part 12UM. Similarly, the second range A2 may be a range centered on the lowermost part 12LM of the core back 12. That is, the lowermost part 12LM may be located in the center of the second range A2, and the second range A2 may extend horizontally symmetrically from the lowermost part 12LM.

[0036] An annular refrigerant flow path 36 extending in the circumferential direction R is provided on the outer circumferential surface 12b of the core back 12. The annular refrigerant flow path 36 is located at an intermediate position in the axial direction X of the core back 12 and is connected to each of the multiple refrigerant flow paths 30. In addition, a refrigerant supply hole 38 connected to the annular refrigerant flow path 36 is provided at an intermediate position in the vertical direction of the casing 18. This allows refrigerant to be supplied to the annular refrigerant flow path 36 from outside the casing 18 through the refrigerant supply hole 38. The refrigerant supplied to the annular refrigerant flow path 36 is divided vertically along the annular refrigerant flow path 36 (see Figure 4) and sent to each of the multiple refrigerant flow paths 30. In particular, by positioning the refrigerant supply hole 38 away from the multiple first refrigerant flow paths 32 and the multiple second refrigerant flow paths 34, the refrigerant is distributed evenly to each of the multiple first refrigerant flow paths 32 and the multiple second refrigerant flow paths 34. Although not particularly limited, in this embodiment the refrigerant supply hole 38 is located in the same horizontal plane as the central axis C and is at the same distance from the plurality of first refrigerant flow paths 32 and the plurality of second refrigerant flow paths 34.

[0037] The stator 10 further comprises a first annular member 22 and a second annular member 24. The first annular member 22 is a member that extends in an annular shape along the circumferential direction R and is made of, for example, a resin material. The first annular member 22 is provided on the first end face 12c of the core back 12. The first annular member 22 extends from the first end face 12c of the core back 12 to the casing 18. The first annular member 22 has a plurality of first refrigerant injection holes 23. The plurality of first refrigerant injection holes 23 are arranged along the circumferential direction R and each is directed toward the first coil end 16a. The refrigerant flowing through the plurality of refrigerant passages 30 is injected from the plurality of first refrigerant injection holes 23 of the first annular member 22 toward the first coil end 16a. As a result, the first coil end 16a is cooled by the refrigerant. Note that the first annular member 22 is not necessarily required. In other words, the refrigerant flowing through the multiple refrigerant channels 30 may be supplied directly from the first end face 12c of the core back 12 to the first coil end 16a.

[0038] The second annular member 24 is a member that extends in an annular shape along the circumferential direction R and is made of, for example, a resin material. The second annular member 24 is provided on the second end face 12d of the core back 12. The second annular member 24 extends from the second end face 12d of the core back 12 to the casing 18. The second annular member 24 has a plurality of second refrigerant injection holes 25. The plurality of second refrigerant injection holes 25 are arranged along the circumferential direction R and each is directed toward the second coil end 16b. The refrigerant flowing through the plurality of refrigerant passages 30 is injected from the plurality of second refrigerant injection holes 25 of the second annular member 24 toward the second coil end 16b. As a result, the second coil end 16b is cooled by the refrigerant. Note that the second annular member 24 is also not necessarily required. That is, the refrigerant flowing through the plurality of refrigerant passages 30 may be supplied directly to the second coil end 16b from the second end face 12d of the core back 12.

[0039] As described above, in the stator 10 of this embodiment, a plurality of refrigerant passages 30 are provided in the core back 12. The plurality of refrigerant passages 30 extend along the axial direction X to the first end face 12c and the second end face 12d of the core back 12. The refrigerant flowing through the refrigerant passages 30 is supplied from the first end face 12c of the core back 12 to the first coil end 16a and from the second end face 12d of the core back 12 to the second coil end 16b. As a result, the first coil end 16a and the second coil end 16b are cooled by the refrigerant.

[0040] In the stator 10 of this embodiment, multiple refrigerant passages 30 are provided only in certain areas A1 and A2 in the circumferential direction of the core back 12. In contrast, in the conventional structure, multiple refrigerant passages 30 were provided around the entire circumference of the core back 12. Compared to the conventional structure, the reduction of some of the multiple refrigerant passages 30 reduces the iron loss of the stator 10 (particularly the iron loss in the core back 12). However, reducing some of the multiple refrigerant passages 30 may result in insufficient cooling of the first coil end 16a and the second coil end 16b. In this regard, in the stator 10 of this embodiment, at least one refrigerant passage 30 is provided at the uppermost part 12UM and the lowermost part 12LM of the core back 12 in the vertical direction.

[0041] According to the above configuration, refrigerant can be effectively supplied to the first coil end 16a and the second coil end 16b. That is, the refrigerant supplied to the first coil end 16a from the refrigerant flow path 30 flows downward due to its own weight, cooling the first coil end 16a. Therefore, by providing the refrigerant flow path 30 at the uppermost part 12UM of the core back 12, refrigerant can be supplied to the uppermost part of the first coil end 16a, allowing the refrigerant to spread throughout the entire first coil end 16a. However, at the bottom of the first coil end 16a, the temperature of the refrigerant has already risen, so there is a risk that the amount of heat absorbed by the refrigerant will be insufficient. Therefore, by providing the refrigerant flow path 30 at the bottommost part 12LM of the core back 12 and directly supplying refrigerant to the bottommost part 12LM of the first coil end 16a, cooling at the bottom of the first coil end 16a can be promoted. The same applies to the second coil end 16b, so redundant explanations will be omitted.

[0042] Furthermore, reducing some of the multiple refrigerant flow paths 30 may degrade the electromagnetic characteristics of the stator 10. In this regard, the stator 10 of this embodiment has a twofold symmetry in the arrangement of the multiple refrigerant flow paths 30, but not a fourfold symmetry. In other words, compared to the conventional structure, the removal of some of the multiple refrigerant flow paths 30 results in the loss of fourfold symmetry, but the maintenance of twofold symmetry. With twofold symmetry maintained, the arrangement of the multiple refrigerant flow paths 30 maintains symmetry in at least two orthogonal directions (for example, the z-direction and the y-direction). This maintains the symmetry of the electromagnetic characteristics required for the stator 10, and prevents the induction of vibrations of the rotor 4.

[0043] In this embodiment, the stator 10 is composed of multiple refrigerant flow paths 30, each consisting of multiple through-holes defined within the core back 12. In contrast, in other embodiments, some or all of the multiple refrigerant flow paths 30 may be composed of one or more grooves defined on the outer circumferential surface 12b of the core back 12. That is, some or all of the multiple refrigerant flow paths 30 may be composed of the space defined between the grooves of the core back 12 and the casing 18. Also, in this embodiment, the annular refrigerant flow path 36 is composed of grooves defined on the outer circumferential surface 12b of the core back 12. In contrast, in other embodiments, the annular refrigerant flow path 36 may be composed of one or more through-holes defined within the core back 12. The number of annular refrigerant flow paths 36 and their positions in the axial direction X are not particularly limited.

[0044] In the stator 10 of this embodiment, the first range A1 and the second range A2 each have an angular range of 120 degrees in the circumferential direction R. In contrast, as shown in Figure 6, in the stator 110 of another embodiment and the electric motor 102 equipped therewith, the first range A1 and the second range A2 each may have an angular range of 45 degrees or less in the circumferential direction R. Even in this case, the first range A1 may be the range centered on the uppermost part 12UM of the core back 12, and the second range A2 may be the range centered on the lowermost part 12LM of the core back 12. In the embodiment shown in Figure 6, the first range A1 and the second range A2 each have an angular range smaller than either the third range A3 or the fourth range A4. With such a configuration, the number of refrigerant flow paths 30 is greatly reduced, so the iron loss of the stator 10 can be greatly reduced.

[0045] In the stators 10 and 110 described above, the multiple refrigerant flow paths 30 are present only in the first range A1 and the second range A2, and not in the third range A3 and the fourth range A4. In contrast, as shown in Figure 7, in the stator 210 of another embodiment and the electric motor 202 equipped therewith, a portion of the multiple refrigerant flow paths 30 is also provided in each of the third range A3 and the fourth range A2. That is, the multiple refrigerant flow paths 30 further include a plurality of third refrigerant flow paths 232 provided in the third range A3 and a plurality of fourth refrigerant flow paths 234 provided in the fourth range A4. The plurality of third refrigerant flow paths 232 and the plurality of fourth refrigerant flow paths 234 are provided symmetrically with respect to the central axis C. As a result, at the first end face 12C of the core back 12, the arrangement of the multiple refrigerant flow paths 30 has twofold symmetry and does not have fourfold symmetry.

[0046] The dimension W1 of the first refrigerant flow path 32 in the circumferential radius R is greater than the dimension W3 of the third refrigerant flow path 232 in the circumferential radius R, and greater than the dimension W4 of the fourth refrigerant flow path 234 in the circumferential radius R. Similarly, the dimension W2 of the second refrigerant flow path 34 in the circumferential radius R is greater than the dimension W3 of the third refrigerant flow path 232 in the circumferential radius R, and greater than the dimension W4 of the fourth refrigerant flow path 234 in the circumferential radius R. Here, the dimension W1 of the first refrigerant flow path 32 in the circumferential radius R is equal to the dimension W2 of the second refrigerant flow path 34 in the circumferential radius R, and the dimension W3 of the third refrigerant flow path 232 in the circumferential radius R is equal to the dimension W4 of the fourth refrigerant flow path 234 in the circumferential radius R. Furthermore, the pitch of the multiple refrigerant flow paths 30 in the circumferential radius R is constant over four ranges A1-A4.

[0047] With the above configuration, a large amount of refrigerant can be preferentially supplied to the uppermost and lowermost parts of the first coil end 16a. This allows for effective cooling of the first coil end 16a. The same applies to the second coil end 16b. Furthermore, in the third range A3 and fourth range A4 of the core back 12, the refrigerant flow path 30 is reduced compared to the first range A1 and second range A2, thereby reducing the iron loss of the stator 10 (especially the iron loss in the core back 12).

[0048] In addition to or instead of the above, the radial dimensions of the first refrigerant flow path 32 and the second refrigerant flow path 34 may be greater than the radial dimensions of the third refrigerant flow path 232 and the fourth refrigerant flow path 234. Here, radial direction refers to the direction perpendicular to both the axial direction X and the circumferential direction R. In addition to or instead of the above, the circumferential pitch of the first refrigerant flow path 32 and the second refrigerant flow path 34 may be greater than the radial dimensions of the third refrigerant flow path 232 and the fourth refrigerant flow path 234. Zhou The pitch in the direction may be smaller. In any configuration, the volume occupancy of the first refrigerant flow path 32 in the first range A1 and the volume occupancy of the second refrigerant flow path 34 in the second range A2 can be made larger than the volume occupancy of the third refrigerant flow path 232 in the third range A3 and larger than the volume occupancy of the fourth refrigerant flow path 234 in the fourth range A4. When this relationship is satisfied, a large amount of refrigerant can be preferentially supplied to the uppermost and lowermost parts of each coil end 16a, 16b. In other words, each coil end 16a, 16b can be effectively cooled. [Explanation of symbols]

[0049] 2, 102, 202: Electric motor, 4: Rotor, 10, 110, 210: Stator, 12: Core back of stator core, 12LM: Bottom of core back, 12UM: Top of core back, 14: Teeth of stator core, 16: Stator coil, 16a: First coil end, 16b: Second coil end, 18: Casing, 22: First annular member, 24: Second annular member, 30: Refrigerant flow path, 32: First refrigerant flow path, 34: Second refrigerant flow path, 36: Annular refrigerant flow path, 38: Refrigerant supply port, 232: Third refrigerant flow path, 234: Fourth refrigerant flow path, A1: First range, A2: Second range, A3: Third range, A4: Fourth range, C: Central axis

Claims

1. A stator for an electric motor, A core back extending cylindrically along the axial direction, Multiple teeth provided on the inner circumferential surface of the core back, The stator coils provided on the plurality of teeth, Equipped with, In a portion of the circumferential region of the core back, a plurality of refrigerant flow paths are arranged along the circumferential direction, extending in the axial direction to the first end face of the core back. The plurality of refrigerant flow paths are, A plurality of first refrigerant flow paths are provided in a first range in the circumferential direction of the core back, which includes the uppermost part in the vertical direction of the core back, The core back includes a plurality of second refrigerant flow paths provided in a second range in the circumferential direction of the core back, which includes the lowest part in the vertical direction of the core back. At the first end face of the core back, the arrangement of the plurality of refrigerant flow paths has twofold symmetry and does not have fourfold symmetry. Outside the first range in the circumferential direction, other refrigerant flow paths exist at positions greater than the pitch of the plurality of first refrigerant flow paths. Outside the circumferential direction of the second range, other refrigerant flows exist at positions greater than the pitch of the plurality of second refrigerant flows. stata.

2. The stator according to claim 1, wherein the uppermost part is located in the center of the first range, and the lowermost part is located in the center of the second range.

3. A stator for an electric motor, A core back extending cylindrically along the axial direction, Multiple teeth provided on the inner circumferential surface of the core back, The stator coils provided on the plurality of teeth, Equipped with, In a portion of the circumferential region of the core back, a plurality of refrigerant flow paths are arranged along the circumferential direction, extending in the axial direction to the first end face of the core back. The plurality of refrigerant flow paths are, A plurality of first refrigerant flow paths are provided in a first range in the circumferential direction of the core back, which includes the uppermost part in the vertical direction of the core back. The core back includes a plurality of second refrigerant flow paths provided in a second circumferential range of the core back, which includes the lowest part of the core back in the vertical direction, At the first end face of the core back, the arrangement of the plurality of refrigerant flow paths has twofold symmetry and does not have fourfold symmetry. Each of the first and second ranges is an angular range of 120 degrees or less in the circumferential direction. stata.

4. The stator according to any one of claims 1 to 3, wherein each of the first range and the second range is an angular range of 45 degrees or less in the circumferential direction.

5. The stator according to any one of claims 1 to 3, wherein the plurality of refrigerant flow paths are not present in the third and fourth circumferential ranges of the core back, the third range and the fourth range which are adjacent to the first range and the second range, respectively.

6. The stator according to any one of claims 1 to 3, wherein at least a portion of the plurality of refrigerant flow paths is composed of a plurality of through holes defined within the core back.

7. A stator for an electric motor, A core back extending cylindrically along the axial direction, Multiple teeth provided on the inner circumferential surface of the core back, The stator coils provided on the plurality of teeth, Equipped with, In a portion of the circumferential region of the core back, a plurality of refrigerant flow paths are arranged along the circumferential direction, extending in the axial direction to the first end face of the core back. The plurality of refrigerant flow paths include a refrigerant flow path located at the uppermost part of the core back in the vertical direction and a refrigerant flow path located at the lowermost part of the core back in the vertical direction. At the first end face of the core back, the arrangement of the plurality of refrigerant flow paths has twofold symmetry and does not have fourfold symmetry. The core back is further provided with an annular refrigerant flow path that extends in the circumferential direction and is connected to each of the plurality of refrigerant flow paths. The annular refrigerant flow path is formed by grooves defined on the outer circumferential surface of the core back. stata.

8. The casing further comprises surrounding the outer circumferential surface of the core back, The stator according to claim 7, wherein the casing has a refrigerant supply hole connected to the annular refrigerant flow path, provided at an intermediate position in the vertical direction.

9. A stator for an electric motor, A core back extending cylindrically along the axial direction, Multiple teeth provided on the inner circumferential surface of the core back, The stator coils provided on the plurality of teeth, Equipped with, In a portion of the circumferential region of the core back, a plurality of refrigerant flow paths are arranged along the circumferential direction, extending in the axial direction to the first end face of the core back. The plurality of refrigerant flow paths include a refrigerant flow path located at the uppermost part of the core back in the vertical direction and a refrigerant flow path located at the lowermost part of the core back in the vertical direction. At the first end face of the core back, the arrangement of the plurality of refrigerant flow paths has twofold symmetry and does not have fourfold symmetry. The first annular member provided on the first end face of the core back further comprises The first annular member has a plurality of first refrigerant injection holes that protrude from the first end face and are directed toward the first coil end of the stator coil. stata.

10. The stator according to claim 9, wherein the plurality of refrigerant flow paths extend along the axial direction to a second end face located opposite to the first end face of the core back.

11. The core back further comprises a second annular member provided on the second end face, The stator according to claim 10, wherein the second annular member has a plurality of second refrigerant injection holes directed toward the second coil end of the stator coil protruding from the second end face.

12. The stator according to any one of claims 1, 3, 7, and 9, A rotor arranged inside the stator, An electric motor equipped with [a specific feature].

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