Motor

Abstract

To provide a technique capable of suppressing an increase in drag loss in a motor including a winding-type rotor.SOLUTION: A motor comprising: a stator; a rotor accommodated inside the stator, the rotor having coils arranged along a circumferential direction of the rotor, the coils extending along an axial direction of the rotor and exhibiting magnetism when energized; and a refrigerant guide including: a refrigerant supply system configured to supply a refrigerant to coil ends of the coils on at least one side of the rotor in the axial direction; a peripheral wall facing the coil ends from an outer side in a radial direction of the rotor on the at least one side in the axial direction of the rotor; and an overhang portion protruding from the peripheral wall to an inner side in the radial direction and facing an outer side portion of the coil ends in a radial direction from an outer side in the axial direction. The overhang portion is configured to guide and discharge at least a part of the cooling medium supplied to the coil end toward the axially outer side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a motor. [Background technology]

[0002] Some motors are equipped with wound rotors (Patent Document 1). Wound rotors have a cylindrical collar that covers the axial coil ends of the rotor to firmly secure the winding coils to the rotor. In wound rotors, a coolant is supplied from outside the rotor to the inside of this collar to cool the coil ends. It is described that a duct is provided to discharge the coolant supplied inside the collar of the wound rotor toward the outer periphery of the collar. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2019-536411 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the refrigerant discharged toward the outer periphery of the collar collides perpendicularly with the coil end of the stator, it tends to increase the amount of refrigerant that penetrates into the gap between the rotor and the stator surrounding the rotor.Furthermore, it was found that the penetration of refrigerant into such gap increases drag loss.

[0005] The present specification provides a technique that can suppress an increase in drag loss in a motor having a wound rotor. [Means for solving the problem]

[0006] The technology disclosed in this specification is embodied in a motor. The motor includes a stator, a rotor housed inside the stator, and coils arranged circumferentially of the rotor, the coils extending axially of the rotor and becoming magnetic when energized, and a refrigerant supply system configured to supply refrigerant to coil ends of the coils on at least one axial side of the rotor, and a refrigerant guide including a peripheral wall on the at least one axial side of the rotor facing the coil ends from a radially outer side of the rotor, and an overhang portion extending radially inward from the peripheral wall and facing the radially outer portions of the coil ends from the axially outer side. The overhang portion is configured to guide and discharge at least a portion of the refrigerant supplied to the coil ends toward the axially outer side.

[0007] In this motor, the coolant supplied to the coil ends is guided and discharged axially outward, away from one end face of the rotor. This prevents the coolant from being discharged axially inward, away from the rotor end face toward the other end of the rotor. This prevents the coolant from entering the gap between the rotor and the stator, which is located axially inward. As a result, an increase in drag loss is suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a plan view of a motor according to a first embodiment, viewed from one end thereof. [Figure 2] FIG. 2 is an enlarged cross-sectional view taken along line II-II in FIG. [Figure 3A] FIG. 4 is a partially enlarged cross-sectional view showing a modified example of the first embodiment. [Figure 3B] FIG. 4 is a partially enlarged cross-sectional view showing a modified example of the first embodiment. [Figure 4] FIG. 10 is a partially enlarged cross-sectional view of one end of a motor according to a second embodiment. [Figure 5A] FIG. 10 is a partially enlarged cross-sectional view showing a modified example of the second embodiment. [Figure 5B]FIG. 10 is a partially enlarged cross-sectional view showing a modified example of the second embodiment. [Figure 5C] FIG. 10 is a partially enlarged cross-sectional view showing a modified example of the second embodiment. [Figure 6A] FIG. 10 is a partially enlarged cross-sectional view showing a modified example of the second embodiment. [Figure 6B] FIG. 10 is a partially enlarged cross-sectional view showing a modified example of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The motor disclosed in this specification includes a stator, a rotor accommodated inside the stator, the rotor including coils arranged circumferentially and extending axially of the rotor, the coils becoming magnetic when energized, and a refrigerant supply system configured to supply refrigerant to coil ends of the coils on at least one axial side of the rotor, and a refrigerant guide including a peripheral wall on the at least one axial side of the rotor facing the coil ends from a radially outer side of the rotor, and an overhang portion extending radially inward from the peripheral wall and facing the radially outer portions of the coil ends from the axially outer side. The overhang portion is configured to guide and discharge at least a portion of the refrigerant supplied to the coil ends toward the axially outer side.

[0010] In another aspect of the motor disclosed in this specification, the axially outer surface of the overhang portion has a slope that slopes toward the axially outer side as it approaches the radially outer side, thereby effectively suppressing the refrigerant from entering the axially inner side and suppressing an increase in drag loss.

[0011] Another aspect of the motor disclosed in this specification includes a configuration in which the coolant cools at least a portion of a stator coil end, which is one end of the coil wound around the stator, via the axially outer surface of the overhang portion, thereby further cooling the stator coil end.

[0012] In another aspect of the motor disclosed in this specification, the overhang portion has at least one refrigerant discharge hole penetrating the overhang portion in the axial direction. This allows the refrigerant that cools the rotor coil ends inside the refrigerant guide to be discharged axially outward through the refrigerant discharge hole with sufficient axial velocity. This effectively suppresses increases in drag loss. Furthermore, the provision of the refrigerant discharge hole generates forced convection of the refrigerant inside the refrigerant guide, enhancing the cooling effect of the coil ends.

[0013] In this aspect, the radially outer inner wall of the at least one refrigerant discharge hole has a slope that slopes radially outward as it approaches the axially outer side. This allows the refrigerant passing through the refrigerant discharge hole to be guided by the slope and discharged axially outward toward the radially outer side. This allows the refrigerant to be directed toward the stator coil ends and other components, thereby effectively cooling them.

[0014] Hereinafter, an embodiment of a motor according to the present disclosure will be described with reference to the accompanying drawings. In this specification, the term "axial direction" refers to the axial direction of the rotor, the term "radial direction" refers to the radial direction of the rotor, and the term "circumferential direction" refers to the circumferential direction about the circumference of the rotor.

[0015] (First embodiment) A motor 2 according to a first embodiment is shown in FIGS. 1 and 2. The motor 2 according to the first embodiment is a motor used in various types of electric vehicles. The motor 2 may be modularized as an e-axle, for example. FIG. 1 is a plan view of the motor 2 from an end portion in the direction A, which is one side in the axial direction, and FIG. 2 is an enlarged view of a cross section of the motor 2 shown in FIG. 1 cut along the axial direction by a straight line along the radial direction. Note that the direction A is an example of the axial outward direction in this specification.

[0016] As shown in FIG. 1, the motor 2 includes a stator 4, a rotor 20, a refrigerant guide 40, and a refrigerant supply system 50. The stator 4 is a cylindrical body extending in the axial direction as a whole. The stator 4 includes a space 6 that penetrates the axial direction and houses the rotor 20. A stator core 8 defines the space 6 of the stator 4, and stator coils 10 are wound in a predetermined manner around a plurality of teeth that protrude radially inward from the stator core 8. Stator coil ends 12 protrude from the stator 4 in the direction A along the circumferential direction of the stator core 8.

[0017] The rotor 20 is housed in a space 6 defined by the stator 4. A gap G exists between the stator 4 and the rotor 20. The rotor 20 includes a rotor core 22, a rotor shaft 24 to which the rotor core 22 is fixed, and coils 26. The rotor core 22 is a cylindrical body that holds the rotor shaft 24 extending in the axial direction. The rotor core 22 includes a plurality of teeth (not shown) that protrude radially outward along its circumferential direction. A slot (not shown) that penetrates in the axial direction is formed between adjacent teeth.

[0018] Coils 26 are wound around the teeth. The wound coils 26 extend axially through the slots 22b. The wound coils 26 form coil ends 28 on the A-direction side of the rotor core 22. The coil ends 28 protrude in the A-direction from the end faces 22a on the A-direction side of the rotor core 22. The amount by which the coil ends 28 protrude in the A-direction is smaller than the amount by which the stator coil ends 12 protrude in the A-direction.

[0019] Coil ends 28 are fixed to end surfaces 22a of rotor core 22 on the A-direction side by fixing members 30 made of a material that does not affect the field current of coils 26. A field current is supplied to coils 26. Note that fixing members 30 are not necessarily required because refrigerant guides 40 are provided.

[0020] The refrigerant guide 40 covers the outer circumferential side and radially outer side of the coil ends 28. The refrigerant guide 40 includes a circumferential wall 42 that protrudes in direction A along the outer circumferential edge on the A side of the rotor core 22, and an overhang portion 44 that is a ring-shaped portion that protrudes radially inward. The circumferential wall 42 faces the coil ends 28 from the radially outer side of the coil ends 28. The circumferential wall 42 is preferably configured to block the discharge of refrigerant from the outer circumferential side of the coil ends 28 to the radially outer side. Blocking the discharge of refrigerant from the outer circumferential side of the coil ends 28 prevents refrigerant from entering the gap G. The circumferential wall 42 is positioned radially outward of the fixing member 30 and is slightly higher than its axial height.

[0021] The overhang portion 44 extends radially inward by a predetermined width from the edge of the peripheral wall 42 on the direction A side as its base. The overhang portion 44 is generally ring-shaped. The overhang portion 44 faces the coil end 28 from the direction A side and covers an area, for example, 50% or less of the length along the radial direction from the outermost peripheral edge of the coil end 28. Therefore, the coil end 28 not covered by the overhang portion 44 is exposed in an opening 45 defined by the inner peripheral edge 44a of the overhang portion 44.

[0022] By providing such a refrigerant guide 40, the refrigerant supplied by the refrigerant supply system 50 through the opening 45 can be received. In addition, the supplied refrigerant can be diffused into the coil ends 28 to cool the coil ends 28.

[0023] An outer surface 46 of the overhang portion 44 on the A-direction side is formed as a slope that slopes in the A-direction, i.e., extends axially outward, as it extends radially outward. The degree of slope is not particularly limited. For example, the outer peripheral edge 44b of the overhang portion 44 roughly coincides with the position of the stator coil end 12 protruding in the A-direction or extends to a position closer to the end face 22a. The overhang portion 44 has such an outer surface 46, which allows the refrigerant to overflow radially outward and in the A-direction through the overhang portion 44.

[0024] A surface 48 opposite to the outer surface 46 of the overhang portion 44 is formed, for example, as a surface parallel to the end surface 22 a of the rotor core 22 , although this is not particularly limited thereto.

[0025] From the viewpoint of cooling effect, the refrigerant guide 40 can be made of a metal material such as aluminum, which has excellent thermal conductivity. From the same viewpoint, it is preferable that the refrigerant guide 40 be fixed by a method that reduces thermal resistance, such as shrink fitting.

[0026] The refrigerant supply system 50 is composed of flow paths that supply refrigerant to the motor 2. The refrigerant supply system 50 includes block flow paths 52a, 52b that supply refrigerant to the coil ends 28. The block flow paths 52a, 52b are arranged symmetrically across the rotor shaft 24. The block flow paths 52a, 52b are also arranged radially outward of the coil ends 28, away from the coil ends 28 in the direction A. The refrigerant may be a hydrophilic fluid in addition to a hydrophobic fluid such as oil.

[0027] The block flow paths 52a and 52b each include two discharge paths 53a and 54a, and two discharge paths 53b and 54b. The discharge paths 53a, 54a, 53b, and 54b are formed to discharge the refrigerant to the coil end 28 exposed at the opening 45.

[0028] Next, we will explain how the coil ends 28 of the motor 2 are cooled. In Figure 2, the movement of the refrigerant is indicated by arrows. When the motor 2 is operating, refrigerant is supplied to the coil ends 28 of the rotating rotor 20 from the block flow paths 52a, 52b and discharge paths 53a, 54a of the refrigerant supply system 50. The refrigerant adheres to and penetrates the radially inner portion of the coil ends 28 from the openings 45. Centrifugal force causes the refrigerant to splash out to the radially outer side of the coil ends 28, but it is caught by the peripheral wall 42 and the overhang portion 44. This cools the radially outer portion of the coil ends 28.

[0029] The refrigerant is stored within the refrigerant guide 40, but eventually overflows from the opening 45. The refrigerant is guided by the centrifugal force caused by the rotation of the rotor 20 and the outer surface 46 of the overhang portion 44, and is discharged obliquely in direction A as it moves radially outward. Because the discharged refrigerant is guided in direction A, it is prevented from entering the gap G between the rotor 20 and the stator 4. This prevents an increase in drag loss. Furthermore, because the outer surface 46 extends to the extent that it reaches the stator coil ends 12, the stator coil ends 12 are also cooled by the overflowing refrigerant.

[0030] The overhang portion 44 of the refrigerant guide 40 can have various shapes. For example, the radially inner surface 146a of the outer surface 146 on the A-side of the overhang portion 144 of the refrigerant guide 140 shown in FIG. 3A is parallel to the end face 22a on the A-side of the rotor core 22, while the radially outer surface 146b is inclined toward the A-side as it approaches the radially outer side. This increases the inclination angle of the surface 146b toward the A-side. This increases the axial velocity of the refrigerant and effectively suppresses an increase in drag loss.

[0031] 3B is entirely parallel to the end face 22a of the rotor core 22 on the A-direction side. In this case, to effectively suppress an increase in drag loss, the radially inner side of the stator coil end 12 in the motor 2 is formed with an inclined surface 14 that slopes toward the radially outer side of the motor 2 as it moves toward the A-direction. This allows the inclined surface 14 to be used as part of the refrigerant guide 240, making it easy to direct the refrigerant in the A-direction. This simplifies the shape of the refrigerant guide 240, suppresses an increase in drag loss, and cools the stator coil end 12.

[0032] The mode of guiding the coolant with the inclined surfaces 14 of the stator coil ends 12 on the radially inner side of the motor 2 can be used in combination with the various modes of coolant guides disclosed in this specification.

[0033] (Second embodiment) In the second embodiment, the refrigerant guide 40 of the first embodiment has refrigerant discharge holes 80-380 in the overhang portion 44. The second embodiment is shown in Fig. 4 and Figs. 5A-5C. Note that in the second embodiment, descriptions of elements common to the first embodiment will be omitted, and the description will focus mainly on the refrigerant discharge holes 80-380. In Fig. 4 and Figs. 5A-5C, the movement of the refrigerant is indicated by arrows.

[0034] As shown in Figure 4, the outer peripheral edge 44b of the overhang portion 44 of the refrigerant guide 40 is provided with a plurality of refrigerant discharge holes 80 along its circumferential direction. The number of refrigerant discharge holes 80 is not particularly limited, but may be determined according to the number of teeth, in other words, one for each coil end 28. The opening positions of the refrigerant discharge holes 80 are also not particularly limited, but may be located at positions corresponding to the centers of the teeth or at positions corresponding to the slots, for example. The opening shape of the refrigerant discharge holes 80 is not particularly limited and may be circular, rectangular, or the like.

[0035] Refrigerant discharge hole 80 penetrates overhang portion 44 in the axial direction. An inner wall 82 on the radially outer side of refrigerant discharge hole 80 has a slope that slopes radially outward as it approaches direction A. As shown in Fig. 4, for example, such a slope is formed on a portion of inner wall 82 close to direction A, and is curved and sloped toward direction A.

[0036] According to the second embodiment, the coil ends 28 and the stator coil ends 12 are cooled by the same refrigerant movement as in the first embodiment, suppressing an increase in drag loss. Furthermore, by providing the refrigerant discharge holes 80, a portion of the refrigerant in the refrigerant guide 40 is guided by the sloped surfaces of the inner walls 82 and discharged from the refrigerant discharge holes 80 in direction A. The refrigerant discharge holes 80 allow the refrigerant to be discharged in direction A at a high axial speed, further suppressing an increase in drag loss. Furthermore, the stator coil ends 12 can be effectively cooled by being guided by the sloped surfaces of the inner walls 82. Furthermore, forced convection is generated within the refrigerant guide 40, improving the cooling performance for the coil ends 28.

[0037] Furthermore, the inclined surfaces of the inner walls 82 of the second embodiment can improve the directionality of the refrigerant toward the stator coil ends 12. Furthermore, because these inclined surfaces have curved surfaces, the precision of the directionality of the refrigerant can also be improved.

[0038] The refrigerant discharge hole 80 can be implemented in various ways. Modified examples of the refrigerant discharge hole 80 are shown in Figures 5A to 5C. The refrigerant discharge hole 180 shown in Figure 5A has a radially outer inner wall 182 that is formed as a slope that linearly slopes toward the radially outer side as it approaches direction A. This type of inner wall 182 can also improve the directionality of the refrigerant toward the stator coil end 12.

[0039] 5B, the radially outer inner wall 282 of the refrigerant discharge hole 280 is formed as a surface parallel to the axial direction. When such an inner wall 282 is provided, the directivity of the refrigerant through the refrigerant discharge hole 280 to the stator coil end 12 may decrease, but it is effective in suppressing an increase in drag loss.

[0040] 5C penetrates axially not at the outer periphery of overhang portion 44 but at a position closer to the inside in the radial direction. Furthermore, radially outer inner wall 382 has a curved slope that slopes radially outward as it approaches direction A. Such refrigerant discharge hole 380 may facilitate the discharge of refrigerant from inside refrigerant guide 40. Furthermore, in cooperation with outer surface 46, it can direct the refrigerant toward stator coil end 12.

[0041] In the overhang portion 44 of the refrigerant guide 40, the refrigerant discharge holes 80, 180, 280, 380 having these various shapes can be used alone or in combination of two or more types.

[0042] Furthermore, for example, these various refrigerant discharge holes 80, 180, 280, 380 can also be applied to the overhang portions 144, 244 of the refrigerant guides 140, 240 shown in Figures 3A and 3B. For example, as shown in Figure 6A, the overhang portion 144 of the refrigerant guide 140 can be provided with a refrigerant discharge hole 80 (the inner wall 82 has a curved, inclined surface). Furthermore, for example, as shown in Figure 6B, the overhang portion 244 of the refrigerant guide 240 can be similarly provided with a refrigerant discharge hole 80.

[0043] Although the coolant supply system 50 in the various embodiments described above supplies coolant to four locations on the coil ends 28, this is not limited to this. The number of locations at which the coolant is supplied to the coil ends 28 may be one or more. However, having many locations at which the coolant is supplied is preferable because it allows the coolant to be uniformly supplied, permeated, accumulated, and overflow inside the coolant guide 40, etc.

[0044] Furthermore, in the various embodiments described above, only the end portion on the A-side, which is one axial direction of the motor 2, has been described, but the coil ends 28 are also present on the other side of the motor 2. Therefore, various types of refrigerant guides 40, etc. can also be applied to the coil ends on both ends of the rotor 20.

[0045] Although specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or in the drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. The technology exemplified in this specification or in the drawings can achieve multiple objectives simultaneously, and achieving one of these objectives itself has technical utility.

[0046] This specification includes the following configurations. [1] A motor, a stator; a rotor housed inside the stator, the rotor having coils extending along the axial direction of the rotor and exhibiting magnetism when energized, arranged along the circumferential direction of the rotor; a refrigerant supply system that supplies a refrigerant to the coil ends of the coils on at least one axial side of the rotor; a refrigerant guide including, on at least one axial side of the rotor, a peripheral wall facing the coil ends from a radially outer side of the rotor, and an overhang portion that protrudes radially inward from the peripheral wall and faces the radially outer portions of the coil ends from the axially outer side; Equipped with The overhang portion is configured to guide and discharge at least a portion of the coolant supplied to the coil end toward the outside in the axial direction. [2] The motor described in [1], wherein the axially outer surface of the overhang portion has a slope that slopes toward the axially outer side as it approaches the radially outer side. [3] A motor as described in [1] or [2], wherein the refrigerant is configured to cool at least a portion of a stator coil end, which is one end of the coil wound around the stator, through the axially outer surface of the overhang portion. [4] The motor according to any one of [1] to [3], wherein the overhang portion has at least one refrigerant discharge hole penetrating in the axial direction. [5] The motor described in [4], wherein the radially outer inner wall of the at least one refrigerant discharge hole has a slope that slopes radially outward as it approaches the axially outer side. [Explanation of symbols]

[0047] 2 motor, 4 stator, 6 space, 8 stator core, 10 coil, 12 coil end, 20 rotor, 22 rotor core, 24 rotor shaft, 26 coil, 28 coil end, 30 fixing member, 40, 140, 240 refrigerant guide, 42 peripheral wall, 44, 144, 244 overhang portion, 44a inner peripheral edge, 44b outer peripheral edge, 45 opening, 46, 146, 246 outer surface, 48 inner surface, 50 refrigerant supply system, 52a, 52b block flow path, 53a, 53b, 54a, 54b discharge path, 80, 180, 280, 380 refrigerant discharge hole, 82, 182, 282, 382 inner wall

Claims

1. A motor, a stator; a rotor housed inside the stator, the rotor having coils extending along the axial direction of the rotor and exhibiting magnetism when energized, arranged along the circumferential direction of the rotor; a refrigerant supply system that supplies a refrigerant to the coil ends of the coils on at least one axial side of the rotor; a refrigerant guide including, on at least one axial side of the rotor, a peripheral wall facing the coil ends from a radially outer side of the rotor, and an overhang portion that protrudes radially inward from the peripheral wall and faces the radially outer portions of the coil ends from the axially outer side; Equipped with The overhang portion is configured to guide and discharge at least a portion of the coolant supplied to the coil end toward the outside in the axial direction.

2. The motor according to claim 1 , wherein the axially outer surface of the overhang portion has a slope that slopes toward the axially outer side as it approaches the radially outer side.

3. 3. The motor according to claim 1, wherein the coolant is configured to cool at least a portion of a stator coil end, which is one end of a coil wound around the stator, via the axially outer surface of the overhang portion.

4. The motor according to claim 1 or 2, wherein the overhang portion has at least one refrigerant discharge hole passing through in the axial direction.

5. The motor according to claim 4 , wherein the radially outer inner wall of the at least one refrigerant discharge hole has a slope that slopes radially outward as it approaches the axially outer side.

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