Rotating Electric Machine

Abstract

To effectively suppress the temperature rise of a coil end and prevent deterioration of the insulation of the coil.SOLUTION: A stator of a rotary electric machine includes a stator core 11 having a plurality of teeth 112, a coil 12 wound around the plurality of teeth 112, and a heat transfer element 13 that transfers heat from the coil 12 to the stator core 11. The coil 12 has a coil end 121 protruding axially from the stator core 11. The heat transfer element 13 is arranged to contact each of an inner surface 121a, which is an inner surface of the coil end 121, and the stator core 11. The heat transfer element 13 has: a plurality of conductive members 130 arranged along a direction orthogonal to a radial direction of the stator core 11; and insulation layers 140 formed respectively between the plurality of conductive members 130.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a rotating electric machine. [Background technology]

[0002] A rotating electric machine such as a motor having a rotor and a stator is known (see Patent Document 1). Patent Document 1 discloses a stator having a stator core, core end members made of a magnetic powder compact arranged to abut on both end faces of the teeth of the stator core, an insulating cap covering the teeth and the core end member, and a coil wound around the outer periphery of the insulating cap. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-369418 A Summary of the Invention [Problem to be solved by the invention]

[0004] The coil of a rotating electric machine generates heat when electricity is passed through it. When the coil becomes hot due to heat, it may cause insulation deterioration. In particular, the coil end is difficult to escape heat, and insulation deterioration is likely to occur due to spontaneous heat generation caused by electricity passing through it. In order to suppress insulation deterioration of the coil end, it is considered to transfer the heat of the coil end to the stator core and suppress the temperature rise of the coil end. The rotating electric machine described in Patent Document 1 is configured such that a core end member is arranged between the coil end and the stator core, and the heat generated at the coil end is transferred to the stator core via the core end member. However, the core end member described in Patent Document 1 is formed of a magnetic powder compact. The magnetic powder compact generally has the same thermal conductivity as resin. For this reason, there is a risk that the temperature rise of the coil end cannot be sufficiently suppressed.

[0005] When a conductive material with high thermal conductivity such as a metal is placed between the coil end and the stator core instead of the magnetic powder composite, leakage magnetic flux distributed in the space surrounding the coil end acts on the conductive material, generating eddy currents. In this case, the heat generated by the conductive material itself may make it difficult to sufficiently suppress the temperature rise of the coil end.

[0006] An object of the present invention is to effectively suppress temperature rise in the coil ends and prevent deterioration of the insulation of the coils. [Means for solving the problem]

[0007] The present invention 1. A rotating electric machine according to the present invention includes a stator and a rotor rotatably provided relative to the stator. The stator includes a stator core having a cylindrical yoke portion and a plurality of teeth protruding from the yoke portion, a coil wound around the plurality of teeth, and a heat transfer body that transfers heat from the coil to the stator core. The coil has coil ends that protrude from the stator core in the axial direction. The heat transfer body is arranged so as to contact the inner peripheral surface of the coil ends and each of the stator core. The heat transfer body includes a plurality of conductive members arranged along a direction perpendicular to the radial direction of the stator core, and an insulating layer formed between the plurality of conductive members. The multiple conductive members are arranged along the axial direction of the stator core, and the thickness of a conductive member arranged axially outside the stator core is thinner than the thickness of a conductive member arranged axially inside the stator core. A rotating electric machine according to a second aspect of the present invention includes a stator and a rotor rotatably provided with respect to the stator. The stator includes a stator core having a cylindrical yoke portion and a plurality of teeth protruding from the yoke portion, a coil wound around the plurality of teeth, and a heat transfer body that transfers heat of the coil to the stator core. The coil has coil ends protruding from the stator core in the axial direction. The heat transfer body is arranged so as to contact the inner peripheral surface of the coil ends and each of the stator core. The heat transfer body includes a plurality of conductive members arranged along a direction perpendicular to the radial direction of the stator core, and an insulating layer formed between the plurality of conductive members. The plurality of conductive members include a pair of conductive members formed in a symmetrical shape with respect to a center plane of the circumferential width of the stator core in the heat transfer body, and the pair of conductive members are adjacent to each other in the circumferential direction of the stator core. Effect of the Invention

[0008] According to the present invention, the temperature rise of the coil end can be effectively suppressed, and the insulation deterioration of the coil can be prevented. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional side view showing the configuration of a rotating electric machine according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional plan view showing the configuration of a rotating electric machine according to an embodiment of the present invention. [Diagram 3]FIG. 3 is a perspective view of only the stator in an area 100A indicated by a dashed line in FIG. [Figure 4] FIG. 4 is an exploded perspective view of a portion of the stator taken along region 100A shown in FIG. [Diagram 5] FIG. 5 is a perspective view of a heat transfer body according to an embodiment of the present invention. [Figure 6] FIG. 6 is a schematic cross-sectional view of a heat transfer body, showing leakage magnetic flux interlinking the heat transfer body and eddy currents generated in the heat transfer body. [Figure 7] FIG. 7 is a schematic cross-sectional view of a heat transfer body, showing the flow of heat generated at the coil end. [Figure 8] FIG. 8 is a perspective view of a portion of a stator of a rotating electric machine according to Modification 1-1 of the embodiment of the present invention. [Figure 9] FIG. 9 is a perspective view of a heat transfer body according to Modification 1-1 of the embodiment of the present invention. [Figure 10A] FIG. 10A is a diagram showing a heat transfer body according to a second modification of the embodiment of the present invention. [Figure 10B] FIG. 10B is a diagram showing a heat transfer body according to the third modification of the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A rotating electric machine according to an embodiment of the present invention will be described with reference to the drawings. The rotating electric machine according to this embodiment is a rotating electric machine suitable for use in driving an automobile (vehicle). The rotating electric machine according to this embodiment can be applied to both a pure electric vehicle that runs only on the rotating electric machine, and a hybrid electric vehicle that is driven by both an engine and a rotating electric machine.

[0011] Fig. 1 is a schematic side cross-sectional view showing the configuration of a rotating electric machine 100 according to an embodiment of the present invention. Fig. 1 shows a cross section of the rotating electric machine 100 cut along a plane parallel to the central axis of rotation Ca of the rotating electric machine 100. Fig. 2 is a schematic plan cross-sectional view showing the configuration of the rotating electric machine 100 according to an embodiment of the present invention. Fig. 2 shows a cross section of the rotating electric machine 100 as seen from the direction of the central axis of rotation Ca.

[0012] The rotating electric machine 100 is a three-phase synchronous motor with embedded permanent magnets. The rotating electric machine 100 operates as an electric motor that rotates a rotor 20 when three-phase AC power is supplied to the rotating electric machine 100. The rotating electric machine 100 may also be driven by an engine (not shown) to operate as a generator and output three-phase AC generated power. In other words, the rotating electric machine 100 may have both a function as an electric motor that generates rotational torque based on electrical energy and a function as a generator that generates power based on mechanical energy.

[0013] As shown in FIGS. 1 and 2, a rotating electric machine 100 includes a stator 10 fixed to a housing 2, and a rotor 20 rotatably provided on the inner peripheral side of the stator 10 with a gap 3 therebetween.

[0014] The stator 10 and the rotor 20 are housed in a cylindrical housing 2. Although not shown, the housing 2 is provided with a plurality of bearings that support the shaft 4 of the rotor 20. The shaft 4 is supported by the plurality of bearings, so that the rotor 20 is rotatably held inside the stator 10.

[0015] The stator 10 includes a cylindrical stator core 11 and a plurality of coils (a U-phase coil, a V-phase coil, and a W-phase coil) 12 wound around the stator core 11. The stator core 11 has a cylindrical yoke portion 111 and a plurality of teeth 112 (36 in this embodiment) protruding from the yoke portion 111 toward the central axis Ca of rotation.

[0016] The central axis Ca of the rotor 20 of the rotating electric machine 100 coincides with the central axis of the cylindrical stator core 11. In the following description, the direction parallel to the central axis Ca of the rotor 20 is referred to as the axial direction, the circumferential direction around the central axis Ca of the rotor 20, i.e., the direction of rotation around the central axis Ca of the rotor 20, is referred to as the circumferential direction, and the direction perpendicular to the axial and circumferential directions is referred to as the radial direction. Hereinafter, unless otherwise specified, the terms "axial direction", "circumferential direction", and "radial direction" refer to the "axial direction", "circumferential direction", and "radial direction" of the rotating electric machine 100, respectively. Note that the "axial direction", "circumferential direction", and "radial direction" of the rotating electric machine 100 are synonymous with the "axial direction", "circumferential direction", and "radial direction" of the stator core 11, respectively.

[0017] 2, a slot 113 for accommodating the coil 12 is formed between adjacent teeth 112. That is, a plurality of slots 113 (36 in this embodiment) are formed in the inner peripheral portion of the stator core 11. In this embodiment, a plurality of teeth 112 extending along the axial direction and slots 113 are alternately formed on the inner peripheral side of the stator core 11 at equal intervals in the circumferential direction. The teeth 112 are formed to have a constant width in the circumferential direction.

[0018] The teeth 112 form a radial magnetic path, and the yoke portion 111 forms a circumferential magnetic path. The teeth 112 guide the rotating magnetic field generated by the coils 12 to the rotor 20, causing the rotor 20 to generate a rotational torque. The coils 12 are wound around the teeth 112 using a concentrated winding method. The coils 12 are, for example, enameled wires in which a conductor mainly made of copper is coated with an insulating coating. The insulating coating of the coils 12 can be made of engineering plastics such as polyimide. The coils 12 of each phase (U phase, V phase, W phase) are formed by connecting multiple concentrated winding coils 120.

[0019] The stator core 11 is made of a magnetic material. In this embodiment, the stator core 11 is formed by laminating a plurality of annular electromagnetic steel plates. The stator core 11 may be formed of a powder core obtained by compression molding insulating coated metal magnetic particles. The stator core 11 is fitted and fixed to the inside of a cylindrical housing 2 (see FIG. 1) by shrink fitting, press fitting, or the like.

[0020] The rotor 20 includes a cylindrical rotor core 21, a plurality of (32 in this embodiment) permanent magnets 22 fixed to the rotor core 21, and a shaft 4 provided to pass through the rotor core 21. The shaft 4 is fixed to the rotor core 21. The rotor core 21 is made of a magnetic material. In this embodiment, the rotor core 21 is formed by laminating a plurality of annular electromagnetic steel plates. The rotor core 21 may be made of a powder core obtained by compression molding insulating coated metal magnetic particles. The outer peripheral surface of the rotor core 21 faces the tip surfaces of the teeth 112, which are the inner peripheral surface of the stator core 11, via a gap 3. The permanent magnets 22 form the field poles of the rotor 20.

[0021] Magnet insertion holes, into which permanent magnets 22 are inserted, are formed at equal intervals in the circumferential direction on the outer periphery of rotor core 21. The inner periphery of permanent magnet 22 is adhesively fixed to the inner periphery of the magnet insertion hole by an adhesive or the like. Note that the method of fixing permanent magnet 22 to rotor core 21 is not limited to this. For example, the outer periphery of rotor core 21 may be provided with a recess for fixing permanent magnet 22.

[0022] The magnetization direction of the permanent magnets 22 is in the radial direction, and the magnetization direction is reversed for each field pole. In other words, if the surface of the permanent magnet 22 that forms a certain magnetic pole is magnetized as an N pole on the stator 10 side and as an S pole on the shaft 4 side, the surface of the permanent magnet 22 that forms the adjacent magnetic pole is magnetized as an S pole on the stator 10 side and as an N pole on the shaft 4 side. The rotor 20 according to this embodiment is a rotor with an even number of magnetic poles (32 in this embodiment).

[0023] Each of the U-phase, V-phase, and W-phase coils 12 is connected to a power converter (inverter) (not shown). DC power from a battery (not shown) is converted to AC power by the power converter and supplied to the coils 12 of each phase, generating a rotating magnetic field and causing the rotor 20 to rotate about the central axis of rotation Ca.

[0024] The concentrated winding coil 120 will be described with reference to Figs. 3 and 4. Fig. 3 is a perspective view of a portion of the stator 10 in the region 100A shown by the broken line in Fig. 2. The region 100A corresponds to an angle (10° in this embodiment) obtained by dividing the stator 10 by the number of teeth 112 (36 in this embodiment). Fig. 4 is an exploded perspective view of a portion of the stator 10 in the region 100A shown in Fig. 3. Note that Figs. 3 and 4 show the conductor of the concentrated winding coil 120 in a schematic manner, but in reality, the conductor is wound helically around the teeth 112. In this embodiment, the conductor of the concentrated winding coil 120 is a rectangular wire, and one concentrated winding coil 120 is attached to one tooth 112. The concentrated winding coil 120 is, for example, a rectangular wire vertically wound coil (edgewise coil) in which a rectangular wire is wound in a direction that is difficult to bend on the edge side (short side). The conductor of the concentrated winding coil 120 may be a round wire.

[0025] The concentrated winding coil 120 is formed in advance by winding a conductor wire in a spiral shape around a jig or the like. The slot 113 has an open slot shape, and the concentrated winding coil 120 is inserted from the inner periphery side of the stator core 11 and attached to the teeth 112. The concentrated winding coil 120 is accommodated in the slot 113 via insulating paper (not shown) having a U-shaped cross section perpendicular to the axial direction. The insulating paper is made of an insulating resin material such as polyphenylene sulfide (PPS) or polybutylene terephthalate (PBT). Although not shown, the coil 12 is formed by connecting the lead wires of the concentrated winding coil 120 to each other. The concentrated winding coil 120 may be wound directly around the teeth 112. In this case, a conductor wire is wound around the outer periphery of the heat transfer body 13 and the teeth 112, which will be described later.

[0026] The concentrated winding coil 120 has an in-slot conductor 122 arranged inside the slot 113, and a coil end 121 that protrudes from the slot 113 in the axial direction of the stator core 11 and is arranged outside the slot 113. The coil end 121 is a portion that connects the in-slot conductor 122 arranged in the slot 113 on one circumferential side of the tooth 112 and the in-slot conductor 122 arranged in the slot 113 on the other circumferential side of the tooth 112. The coil end 121 corresponds to an axial end of the stator core 11 in the concentrated winding coil 120, and is exposed by protruding from the stator core 11. In this embodiment, the coil end 121 is bent into a semicircular shape.

[0027] Incidentally, a rotating electric machine used in a vehicle or the like, such as the rotating electric machine 100 according to the present embodiment, is required to be able to be installed in as small a space as possible and to be able to output a large driving torque. For this reason, the rotating electric machine needs to have a large diameter, a thin size, and high output. When shortening a rotating electric machine as a concentrated winding permanent magnet synchronous motor in the axial direction, it is preferable to adopt a fractional slot winding structure as a structure with a high winding factor that affects the torque increase of the rotating electric machine. In the present embodiment, a fractional slot winding structure with a ratio of the number of slots to the number of poles of 9:8 is adopted. In contrast to a general combination structure with a ratio of the number of slots to the number of poles of 3:2, the fractional slot winding structure has a higher winding factor as the values ​​of the number of slots and the number of poles are closer. On the other hand, the fractional slot winding structure has a larger number of coils for the rotating electric machine than a general structure. For this reason, insulation deterioration is likely to occur due to damage to the insulating coating of the coils and the insulating varnish fixed to the coils.

[0028] The magnitude of torque of a rotating electric machine (motor) is usually proportional to the axial length and current of the rotating electric machine. However, due to restrictions on installation space, it may be difficult to ensure a sufficient axial length of the rotating electric machine. In this case, a large current is passed through the coil to obtain high output, so it is important to effectively dissipate the Joule heat generated at the coil end and prevent deterioration of the insulation of the coil end.

[0029] The stator 10 according to this embodiment includes a heat transfer body 13 that transfers heat from the coil ends 121 to the stator core 11. The heat transfer body 13 is disposed between the coil ends 121 and the stator core 11. The heat from the coil ends 121 is transferred to the stator core 11 via the heat transfer body 13, and then transferred from the stator core 11 to the housing 2, where it is dissipated to the outside of the housing 2.

[0030] Here, when the heat transfer body 13 is formed from a single conductive member made of a metal material or the like having high thermal conductivity, the heat transfer body 13 generates heat due to eddy currents generated by leakage magnetic flux linking with the heat transfer body 13, resulting in a problem that the heat of the coil end 121 cannot be effectively dissipated.

[0031] In order to solve the above problems, the heat transfer body 13 according to this embodiment has a structure in which a plurality of conductive members 130 are laminated with insulating layers 140 interposed therebetween. In other words, the heat transfer body 13 has a divided structure in which it is divided into a plurality of conductive members 130. This suppresses the generation of heat caused by eddy currents generated in the heat transfer body 13, and allows the heat of the coil ends 121 to be effectively transferred to the stator core 11, thereby suppressing insulation deterioration of the coil ends 121.

[0032] The configuration of heat transfer body 13, the eddy currents generated in heat transfer body 13, and the flow of heat generated in coil ends 121 will be described in detail below with reference to Fig. 3 to Fig. 6. Fig. 5 is a perspective view of heat transfer body 13. Fig. 6 is a schematic cross-sectional view of heat transfer body 13, showing leakage flux interlinked with heat transfer body 13 and eddy currents generated in heat transfer body 13. Fig. 7 is a schematic cross-sectional view of heat transfer body 13, showing the flow of heat generated in coil ends 121.

[0033] As shown in Figs. 3 and 4, the heat transfer body 13 is disposed between the inner peripheral surface 121a, which is the surface on the inner peripheral side of the coil end 121, and the axial end surface 112a, which is the axial end surface of the tooth 112. The heat transfer body 13 has a semi-cylindrical shape and has a flat bottom surface 13b formed along the axial end surface 112a of the tooth 112, and an outer peripheral surface 13a, which is a circular arc-shaped curved surface formed along the inner peripheral surface 121a of the coil end 121. The outer peripheral surface 13a abuts against the inner peripheral surface 121a of the coil end 121, and the bottom surface 13b abuts against the axial end surface 112a of the tooth 112. As a result, the coil end 121 and the tooth 112 are thermally connected via the heat transfer body 13. As shown in the drawings, one heat transfer body 13 is disposed on each of one axial side and the other axial side of the tooth 112.

[0034] As shown in FIG. 5, the heat transfer body 13 includes a first conductive member 131 having a semicircular cross section, a second conductive member 132 having a semicircular cross section, a third conductive member 133 having a semicircular cross section, a fourth conductive member 134 having a semicircular cross section, and a fifth conductive member 135 having a semicircular cross section. Hereinafter, the first to fifth conductive members 131 to 135 are collectively referred to as conductive members 130. The conductive members 130 are formed of a metal material having electrical conductivity. The conductive members 130 are preferably formed of a nonmagnetic material. Furthermore, the conductive members 130 are preferably formed of a material having a higher thermal conductivity than the stator core 11. The conductive members 130 are formed of a nonmagnetic material having a high thermal conductivity, such as an aluminum alloy (JIS: A5052, etc.) or stainless steel (JIS: SUS304, etc.). In this embodiment, all of the conductive members 130 constituting the heat transfer body 13 are formed of the same material.

[0035] The thermal conductivity of aluminum alloy (JIS: A5052) is 137 [W / mK] and the electrical resistivity is 2.66e -8 [Ωm]. The thermal conductivity of stainless steel (JIS: SUS304) is 16 [W / mK] and the electrical resistivity is 7.19e -7The thermal conductivity of the electromagnetic steel sheet (JIS: 35A250) constituting the stator core 11 is 28.5 [W / mK] and the electrical resistivity is 4.7e -7 [Ωm]. Since the stator core 11 is formed by laminating electromagnetic steel sheets, its thermal conductivity is anisotropic. The thermal conductivity of the stator core 11 in the in-plane direction of the electromagnetic steel sheets is approximately the same as that of the electromagnetic steel sheets, but the thermal conductivity in the axial direction of the stator core 11, i.e., the lamination direction of the electromagnetic steel sheets, is smaller than the thermal conductivity in the in-plane direction of the electromagnetic steel sheets. The thermal conductivity of the stator core 11 in the axial direction (lamination direction of the electromagnetic steel sheets) according to this embodiment is 5.8 [W / mK]. That is, the thermal conductivity of aluminum alloy (JIS: A5052) and stainless steel (JIS: SUS304), which are materials of the conductive member 130, is higher than the thermal conductivity of the stator core 11 in the axial direction.

[0036] The first to fourth conductive members 131 to 134 are arch-shaped members having a semicircular cross section. The circumferential end faces of the first to fourth conductive members 131 to 134 are core contact surfaces 131b to 134b that come into surface contact with the stator core 11. The outer peripheral surface 13a, which is the surface on the outer peripheral side of the first conductive member 131, is a coil contact surface that comes into contact with the coil end 121. The inner peripheral surface, which is the surface on the inner peripheral side of the first conductive member 131, comes into contact with the outer peripheral surface, which is the surface on the outer peripheral side of the second conductive member 132, the inner peripheral surface, which is the surface on the inner peripheral side of the second conductive member 132, comes into contact with the outer peripheral surface, which is the surface on the outer peripheral side of the third conductive member 133, and the inner peripheral surface, which is the surface on the inner peripheral side of the third conductive member 133, comes into contact with the outer peripheral surface, which is the surface on the outer peripheral side of the fourth conductive member 134.

[0037] The fifth conductive member 135 is a semi-cylindrical member having a semicircular cross section. An outer peripheral surface, which is the surface on the outer peripheral side of the fifth conductive member 135, contacts an inner peripheral surface, which is the surface on the inner peripheral side of the fourth conductive member 134. The fifth conductive member 135 has a surface (bottom surface) corresponding to a chord of the cross-sectional shape as a core contact surface 135b that comes into surface contact with the stator core 11.

[0038] The conductive members 130 are connected to each other with an adhesive. Furthermore, the outer peripheral surface 13a of the first conductive member 131 and the coil end 121 are connected with an adhesive, and the core contact surfaces 131b to 135b of each conductive member 130 and the stator core 11 are connected with an adhesive. The adhesive is, for example, a two-part epoxy adhesive or a silicone adhesive. As shown in FIG. 6, the adhesive hardens to form an insulating layer (hardened adhesive) 140, which is a layered member having insulating properties.

[0039] When the conductive members 130 are connected to each other by the adhesive, intermediate insulating layers 142 to 145 are formed between the conductive members 130. Specifically, the intermediate insulating layer 142 is formed between the inner peripheral surface of the first conductive member 131 and the outer peripheral surface of the second conductive member 132. The intermediate insulating layer 143 is formed between the inner peripheral surface of the second conductive member 132 and the outer peripheral surface of the third conductive member 133. The intermediate insulating layer 144 is formed between the inner peripheral surface of the third conductive member 133 and the outer peripheral surface of the fourth conductive member 134. The intermediate insulating layer 145 is formed between the inner peripheral surface of the fourth conductive member 134 and the outer peripheral surface of the fifth conductive member 135. When the adhesive hardens, the conductive members 130 are bonded together to form the heat transfer body 13.

[0040] The core contact surfaces 131b-135b of each conductive member 130, which are the bottom surface 13b of the heat transfer body 13, are fixed to the axial end surface 112a of the tooth 112 by an adhesive. When the tooth 112 and the heat transfer body 13 are connected by an adhesive, an inner insulating layer 146 is formed between the tooth 112 and the heat transfer body 13. Specifically, the inner insulating layer 146 is formed between the core contact surfaces 131b-134b of the first to fourth conductive members 131-134 and the core contact surface 135b of the fifth conductive member 135 and the axial end surface 112a of the tooth 112. Therefore, each conductive member 130 contacts the stator core 11 via the inner insulating layer 146 and is thermally connected to the stator core 11.

[0041] The outer peripheral surface 13a of the heat transfer body 13 is fixed to the inner peripheral surface 121a of the coil end 121 by an adhesive. When the coil end 121 and the heat transfer body 13 are connected by an adhesive, an outer insulating layer 141 is formed between the inner peripheral surface 121a of the coil end 121 and the outer peripheral surface 13a of the heat transfer body 13. Therefore, the first conductive member 131 contacts the coil end 121 via the outer insulating layer 141 and is thermally connected to the coil end 121. Note that the coil end 121 has an insulating coating. Therefore, the outer insulating layer 141 can be omitted. In this case, the first conductive member 131 directly contacts the coil end 121.

[0042] In this manner, the multiple conductive members 130 are arranged along the axial direction of the stator core 11 with the insulating layers 140 interposed therebetween. In other words, the heat transfer body 13 is a laminated structure in which the insulating layers 140 and the conductive members 130 are alternately laminated. The heat transfer body 13 is fixed so as to be sandwiched between the coil ends 121 and the teeth 112.

[0043] When a current is supplied to the coil 12, a magnetic field is generated around the coil 12, and a part of the magnetic field becomes leakage magnetic flux Lf. The leakage magnetic flux Lf that links with the conductive member 130 is parallel to the radial direction of the stator core 11. That is, the leakage magnetic flux Lf that links with the conductive member 130 is perpendicular to a cross section of the conductive member 130 that is perpendicular to the radial direction of the stator core 11 (hereinafter, also referred to as a linkage plane of the leakage magnetic flux). During the operation of the rotating electric machine 100, the magnitude of the current that flows through the coil 12 changes periodically. Therefore, the leakage magnetic flux Lf that is generated due to the current flowing through the coil 12 also changes in the same manner. As a result, the leakage magnetic flux Lf that links with the conductive member 130 generates an eddy current Ec inside the conductive member 130. The eddy current Ec is generated around the multiple leakage magnetic fluxes Lf, and the composite eddy current (see the thick dashed line in the figure) flows along the vicinity of the outer periphery of the conductive member 130.

[0044] The magnitude of the eddy current Ec is proportional to the magnitude of the leakage flux Lf and to the area of ​​the interlinkage surface of the leakage flux Lf. In other words, the loss caused by the eddy current Ec (hereinafter also referred to as eddy current loss) can be reduced by reducing the area of ​​the interlinkage surface of the leakage flux Lf. The eddy current loss Pe [W / kg] is generally expressed by formula (1). Pe = σ × (d × f × k × B) 2 …(1) Here, σ is a constant of the material of the conductive member 130, d is the thickness of the conductive member 130, f is the frequency of the magnetic flux, k is the form factor of the electromotive force, and B is the interlinked magnetic flux density. As expressed by formula (1), the eddy current loss Pe is proportional to the square of the thickness of the conductive member 130. The narrower the area of ​​the path through which the eddy current flows, the greater the resistance of the eddy current circuit and the smaller the eddy current.

[0045] The semi-cylindrical heat transfer body 13 according to this embodiment is divided into four arch-shaped members (first to fourth conductive members 131 to 134) and one semi-cylindrical member (fifth conductive member 135). In this embodiment, each conductive member 130 is formed so that the thickness thereof decreases as it is disposed closer to the outside in the axial direction. Specifically, the magnitude relationship between the thickness t1 of the first conductive member 131, the thickness t2 of the second conductive member 132, the thickness t3 of the third conductive member 133, the thickness t4 of the fourth conductive member 134, and the thickness t5 of the fifth conductive member 135 is as follows: <t2<t3<t4<t5となる。

[0046] The thickness of the conductive member 130 can be said to be the axial length on the center plane of the circumferential width (the width of the conductive member 130 in the circumferential direction of the stator core 11). Specifically, the thickness t1 of the first conductive member 131 can be said to be the axial length on the center plane of the circumferential width of the first conductive member 131. The thickness t2 of the second conductive member 132 can be said to be the axial length on the center plane of the circumferential width of the second conductive member 132. The thickness t3 of the third conductive member 133 can be said to be the axial length on the center plane of the circumferential width of the third conductive member 133. The thickness t4 of the fourth conductive member 134 can be said to be the axial length on the center plane of the circumferential width of the fourth conductive member 134. The thickness t5 of the fifth conductive member 135 can be said to be the axial length on the center plane of the circumferential width of the fifth conductive member 135. The thickness t5 of the fifth conductive member 135 corresponds to the radius of the semi-cylindrical fifth conductive member 135.

[0047] In this way, the conductive members 130 each have a different thickness. Also, the thickness of each conductive member 130 is greater than the thickness of the electromagnetic steel sheets that form the stator core 11.

[0048] By making the thickness of the conductive member 130 thinner toward the outside, the difference in the area of ​​the interlinkage surface of the leakage flux Lf in each conductive member 130 can be reduced. The effect obtained by reducing the difference in the area of ​​the interlinkage surface of the leakage flux Lf in each conductive member 130 will be described. The outermost conductive member 130 has a longer circumferential length. Therefore, if the thickness of each conductive member 130 is the same, the conductive member 130 arranged on the outside has a larger area of ​​the interlinkage surface of the leakage flux Lf than the conductive member 130 arranged on the inside. Therefore, if the thickness of each conductive member 130 is the same, the outer conductive member 130 having a larger area of ​​the interlinkage surface of the leakage flux Lf generates a larger eddy current loss.

[0049] In contrast, the conductive members 130 constituting the heat transfer body 13 according to this embodiment are formed so that the thickness of the conductive members 130 arranged on the outer side is thinner. In other words, the thickness of the conductive members 130 (for example, the first conductive member 131) arranged on the axial outer side of the stator core 11 is thinner than the thickness of the conductive members 130 (for example, the second conductive member 132) arranged on the axial inner side of the stator core 11 than the conductive members 130 (for example, the first conductive member 131). Therefore, the difference in area of ​​the interlinkage surface of the leakage magnetic flux Lf in each conductive member 130 (for example, the difference between the area of ​​the interlinkage surface of the leakage magnetic flux Lf in the first conductive member 131 and the area of ​​the interlinkage surface of the leakage magnetic flux Lf in the second conductive member 132) can be reduced. Therefore, the magnitude of the eddy current generated in each conductive member 130 during operation of the rotating electric machine 100 can be reduced and made uniform, and the heat generation amount of the heat transfer body 13 can be kept low. As a result, the heat of coil 12 can be effectively transferred to stator core 11 by heat transfer body 13, and the temperature of coil 12 can be effectively reduced.

[0050] The multiple conductive members 130 are preferably formed so that they have the same cross-sectional area (i.e., the area of ​​the interlinkage surface of the leakage magnetic flux Lf) perpendicular to the radial direction of the stator core 11. This makes it possible to uniformly and lowly reduce eddy current loss in each conductive member 130, thereby suppressing heat generation from the heat transfer body 13 itself.

[0051] 7, as shown by dashed arrows, heat generated in coil end 121 is transferred in the order of first conductive member 131, second conductive member 132, third conductive member 133, fourth conductive member 134, and fifth conductive member 135. The heat transferred to first conductive member 131 is transferred along the circumferential direction of arc-shaped first conductive member 131, and is transferred from core contact surface 131b to teeth 112 via inner insulating layer 146. Similarly, the heat transferred to second to fourth conductive members 132 to 134 is transferred along the circumferential direction of arc-shaped second to fourth conductive members 132 to 134, and is transferred from core contact surfaces 132b to 134b to teeth 112 via inner insulating layer 146. The heat transferred to the fifth conductive member 135 is conducted along the axial direction of the stator core 11 and is transferred from the core contact surface 135b to the teeth 112 via the inner insulating layer 146.

[0052] In this manner, in this embodiment, a heat transfer path is constructed to transfer Joule heat generated in the coil ends 121 of the coils 12 to the teeth 112 via the heat transfer body 13 during operation of the rotating electric machine 100. The heat transferred to the teeth 112 is transferred to the housing 2 (see FIG. 2) via the yoke portion 111 (see FIG. 2) and dissipated to the external environment. Therefore, according to this embodiment, the temperature of the coils 12 can be lowered compared to a case in which the heat transfer body 13 is not provided.

[0053] According to the above-described embodiment, the following advantageous effects are obtained.

[0054] (1) A rotating electric machine 100 includes a stator 10 and a rotor 20 rotatably provided relative to the stator 10. The stator 10 includes a stator core 11 having a cylindrical yoke portion 111 and a plurality of teeth 112 protruding from the yoke portion 111, a coil 12 wound around the plurality of teeth 112, and a heat transfer body 13 that transfers heat of the coil 12 to the stator core 11. The coil 12 has a coil end 121 protruding from the stator core 11 in the axial direction of the stator core 11. The heat transfer body 13 is disposed so as to contact both an inner circumferential surface 121a, which is the surface on the inner circumferential side of the coil end 121, and the stator core 11. The heat transfer body 13 includes a plurality of conductive members 130 arranged along a direction perpendicular to the radial direction of the stator core 11 (the axial direction in this embodiment), and an insulating layer 140 formed between the plurality of conductive members 130.

[0055] In this configuration, the heat transfer body 13 can be formed of a conductive member 130 made of a metal material or the like having good thermal conductivity. In addition, since the heat transfer body 13 is divided into a plurality of conductive members 130, eddy current loss can be reduced compared to when the heat transfer body is a single piece of metal material. Therefore, according to this embodiment, heat generation in the heat transfer body 13 itself due to eddy currents can be suppressed, so that heat generated in the coil end 121 can be effectively transferred to the stator core 11 via the heat transfer body 13. This effectively suppresses the temperature rise in the coil end 121, and prevents insulation deterioration of the coil.

[0056] In this embodiment, the temperature rise of the coil end 121 can be suppressed, thereby improving the output of the rotating electric machine 100. Furthermore, according to this embodiment, it is possible to provide a rotating electric machine 100 for driving a vehicle that has high durability and can operate continuously even in a high-temperature environment inside the vehicle.

[0057] (2) The multiple conductive members 130 include a first conductive member 131 formed along the inner circumferential surface 121a, which is the surface on the inner circumferential side of the coil end 121. In other words, the outer circumferential surface 13a, which is the surface on the outer circumferential side of the heat transfer body 13, is formed along the inner circumferential surface 121a of the coil end 121. With this configuration, the contact area between the coil end 121 and the heat transfer body 13 can be increased, and the thermal contact resistance can be reduced. As a result, the heat transfer body 13 can transfer more heat to the stator core 11, so that the temperature rise of the coil 12 can be effectively suppressed.

[0058] (3) The thickness of the conductive member 130 arranged on the axially outer side of the stator core 11 is thinner than the thickness of the conductive member 130 arranged on the axially inner side of the stator core 11. With this configuration, it is possible to reduce the difference in area of ​​the interlinkage surface of the leakage magnetic flux Lf in each conductive member 130. This makes it possible to reduce eddy current loss and suppress heat generation of the heat transfer body 13 itself. As a result, it is possible to effectively suppress the temperature rise of the coil 12.

[0059] (4) The plurality of conductive members 130 constituting the heat transfer body 13 are made of a non-magnetic material. Non-magnetic materials have the property of being less permeable to magnetic flux than magnetic materials. Therefore, according to this embodiment, eddy current loss can be reduced compared to when the conductive members 130 are made of a magnetic material. Furthermore, when the conductive members 130 are made of a magnetic material, hysteresis loss occurs. In contrast, in this embodiment, since the conductive members 130 are made of a non-magnetic material, heat generation caused by hysteresis loss can be suppressed compared to when the conductive members 130 are made of a magnetic material.

[0060] (5) All of the multiple conductive members 130 constituting the heat transfer body 13 have core contact surfaces 131b to 135b that are in surface contact with the stator core 11 via the inner insulating layer 146. Therefore, the heat transferred to each conductive member 130 can be transferred directly from each conductive member 130 to the stator core 11. As a result, the temperature rise of the coil 12 can be effectively suppressed.

[0061] (6) The thermal conductivity of the multiple conductive members 130 constituting the heat transfer body 13 is higher than the thermal conductivity in the axial direction of the stator core 11. This allows the heat of the coil ends 121 to be transferred to the stator core 11 more effectively than when the thermal conductivity of the conductive members 130 is lower than the thermal conductivity in the axial direction of the stator core 11. As a result, the temperature rise of the coils 12 can be effectively suppressed.

[0062] (7) All of the multiple conductive members 130 constituting the heat transfer body 13 are made of the same material. This reduces manufacturing costs compared to when the multiple conductive members 130 are made of different materials. In addition, the only parameter required to make the eddy current loss uniform is the area of ​​the interlinkage surface of the leakage magnetic flux, which reduces the design effort.

[0063] The following modified examples are also within the scope of the present invention, and it is possible to combine the configurations shown in the modified examples with the configurations described in the above-mentioned embodiments, or to combine the configurations described in the different modified examples below.

[0064] <Variation 1> In the above embodiment, an example in which the multiple conductive members 130 are arranged along the axial direction of the stator core 11 has been described, but the present invention is not limited to this. The multiple conductive members 130 may be arranged along at least one of the axial direction and the circumferential direction of the stator core 11. If the multiple conductive members 130 are arranged along a direction perpendicular to the leakage flux Lf that links with the conductive members 130, eddy current loss can be reduced. In other words, the heat transfer body 13 may be configured to be divided so that a dividing line is formed on the radial end face of the stator core 11.

[0065] <Variation 1-1> 8 and 9, the plurality of conductive members 230 may be arranged along the axial direction and the circumferential direction of the stator core 11. As shown in Fig. 8 and 9, in this modification 1-1, the plurality of conductive members 230 include a pair of first conductive members 231a, 231b formed in a symmetrical shape with respect to the central plane of the circumferential width W of the stator core 11 in the heat transfer body 23, a pair of second conductive members 232a, 232b formed in a symmetrical shape with respect to the central plane of the circumferential width W of the stator core 11 in the heat transfer body 23, and a pair of third conductive members 233a, 233b formed in a symmetrical shape with respect to the central plane of the circumferential width W of the stator core 11 in the heat transfer body 23.

[0066] The pair of first conductive members 231a, 231b are shaped by dividing an arch-shaped conductive member having a semicircular cross section into two equal parts (left and right halves) in the circumferential direction of stator core 11. Similarly, the pair of second conductive members 232a, 232b are shaped by dividing an arch-shaped conductive member having a semicircular cross section into two equal parts (left and right halves) in the circumferential direction of stator core 11. The pair of third conductive members 233a, 233b are shaped by dividing a semicylindrical conductive member having a semicircular cross section into two equal parts (left and right halves) in the circumferential direction of stator core 11.

[0067] The first conductive member 231a and the first conductive member 231b are arranged in the circumferential direction of the stator core 11 and are adjacent to each other in the circumferential direction. The second conductive member 232a and the second conductive member 232b are arranged in the circumferential direction of the stator core 11 and are adjacent to each other in the circumferential direction. The third conductive member 233a and the third conductive member 233b are arranged in the circumferential direction of the stator core 11 and are adjacent to each other in the circumferential direction.

[0068] The first conductive member 231a, the second conductive member 232a, and the third conductive member 233a are arranged in the axial direction of the stator core 11. Similarly, the first conductive member 231b, the second conductive member 232b, and the third conductive member 233b are arranged in the axial direction of the stator core 11. Note that it is preferable that each conductive member 230 is formed so that the areas of the interlinkage surfaces of the leakage magnetic flux Lf are the same.

[0069] According to this configuration, the same effect as the above embodiment is achieved. The heat transfer body 23 according to this modification is configured to be divided not only in the axial direction but also in the circumferential direction, so that the area of ​​the interlinking surface of the leakage magnetic flux Lf can be easily reduced. As a result, the temperature rise of the coil 12 can be more effectively suppressed. In addition, in the configuration in which the heat transfer body 23 is divided into two equal parts left and right at the center of the width direction, the transfer path of heat transferred from the coil end 121 to the stator core 11 is the same as the path when the heat transfer body 23 is not divided into two equal parts left and right. Therefore, the heat of the coil end 121 can be effectively transferred to the stator core 11.

[0070] <Variation 1-2> 8 and 9, the multiple conductive members 230 are arranged along the axial direction and circumferential direction of the stator core 11, but the first conductive member 231a, the second conductive member 232a, and the third conductive member 233a may be formed as a single conductive member, and the first conductive member 231b, the second conductive member 232b, and the third conductive member 233b may be formed as a single conductive member. In other words, the multiple conductive members 230 may be arranged only along the circumferential direction of the stator core 11.

[0071] <Modification 1-3> The heat transfer body may have a configuration in which three or more conductive members are arranged only along the circumferential direction of the stator core 11. In this case, it is preferable to make the thickness (circumferential width) of the conductive members thinner as they are closer to the center of the circumferential width of the heat transfer body. This makes it possible to reduce the difference in area of ​​the interlinkage surfaces of the leakage magnetic flux Lf of each of the conductive members, and to reduce and uniform the eddy current loss.

[0072] <Variation 2> In the above embodiment, an example has been described in which all of the multiple conductive members 130 constituting the heat transfer body 13 have the core contact surfaces 131b to 135b that come into surface contact with the stator core 11, but the present invention is not limited to this. For example, as shown in Fig. 10A, conductive members 330 having a sector-shaped cross section may be arranged in the circumferential direction of the stator core 11. In the example shown in Fig. 10A, the multiple conductive members 330 are arranged along the inner circumferential surface 121a of the coil end 121.

[0073] In the example shown in FIG. 10A, the heat transfer body 33 has a first conductive member 331 having a core contact surface 331b in face-to-face contact with the teeth 112, a second conductive member 332 adjacent to the first conductive member 331, a third conductive member 333 adjacent to the second conductive member 332, and a fourth conductive member 334 adjacent to the third conductive member 333 and having a core contact surface 334b ​​in face-to-face contact with the teeth 112.

[0074] According to this modification, as in the above embodiment, the eddy current loss generated in the conductive member 330 can be reduced, and the temperature rise of the coil 12 can be effectively suppressed. The heat transferred to the second conductive member 332 is transferred to the stator core 11 via the first conductive member 331. The heat transferred to the third conductive member 333 is transferred to the stator core 11 via the fourth conductive member 334. That is, in the heat transfer body 33 according to this modification 1-3, the thermal resistance of the heat transfer path is higher than that of the above embodiment. For this reason, it is preferable to provide the core contact surfaces 131b to 135b on each conductive member 130 as in the above embodiment, thereby reducing the thermal resistance of the heat transfer path.

[0075] <Variation 3> As shown in FIG. 10B, the heat transfer body 43 may be configured to have a conductive member 431 with a bow-shaped cross section and flat conductive members 432, 433, and 434 arranged in the axial direction of the stator core 11. The conductive members 432, 433, and 434 have planar outer and inner surfaces and a curved surface that contacts the inner circumferential surface 121a of the coil end 121. The conductive member 431 has an arc-shaped curved surface and a flat surface that corresponds to a chord of the cross-sectional shape. In this modification 1-4, among the multiple conductive members 430 (431 to 435), the one disposed on the outer side in the axial direction is thicker. This can reduce the difference in area of ​​the interlinkage surfaces of the leakage magnetic flux Lf of each of the multiple conductive members 430, and can reduce and equalize eddy current loss.

[0076] <Modification 4> In the above embodiment, an example in which the conductive members 130 are connected to each other by an adhesive has been described, but the present invention is not limited to this. Instead of an adhesive, the conductive members 130 may be connected to each other by spot welding. In this case, an insulating layer made of an oxide film or the like is formed on the surface of the conductive member 130, and insulation between the conductive members 130 is ensured. Furthermore, when an insulating layer such as an oxide film is formed on the surface of the conductive member 130, a fixing member may be further provided to fix the heat transfer body 13 to the stator core 11 by pressing it from the axial outside instead of spot welding.

[0077] <Variation 5> In the above embodiment, the coil end 121 is bent into a semicircular shape, but the present invention is not limited to this. The coil end 121 may be bent into a trapezoid or a rectangular shape.

[0078] <Variation 6> Heat transfer body 13 may be configured to extend radially outward of stator core 11 along teeth 112 and abut against housing 2. Heat transfer body 13 contacts housing 2 and transfers heat from coil end 121 directly to housing 2. This configuration can more effectively suppress temperature rise in coil end 121. Note that the heat dissipation effect may be improved by providing a refrigerant passage in housing 2 through which a refrigerant flows.

[0079] <Variation 7> In the above embodiment, an example has been described in which the multiple conductive members 130 constituting the heat transfer body 13 are made of the same material, but the present invention is not limited to this. The leakage magnetic flux Lf increases closer to the coil end 121. For this reason, the outer conductive members 130 of the heat transfer body 13 (for example, the first conductive member 131 to the third conductive member 133) may be made of a material with high electrical resistivity, and the inner conductive members 130 of the heat transfer body 13 (for example, the fourth conductive member 134 and the fifth conductive member 135) may be made of a material with low electrical resistivity.

[0080] <Variation 8> The number of conductive members 130 constituting the heat transfer body 13 is not limited to the example described in the above embodiment. The greater the number of conductive members 130 constituting the heat transfer body 13, the smaller the eddy current loss.

[0081] <Variation 9> The number of slots and the number of poles of the rotating electric machine are not limited to the examples described in the above embodiment.

[0082] <Modification 10> In the above embodiment, a rotating electric machine mounted on an automobile has been described as an example, but the present invention is not limited thereto. The present invention can be applied to various moving bodies that generate driving force by a rotating electric machine, such as elevators and railroad cars. The rotating electric machine is not limited to being mounted on a moving body. The present invention can be applied to rotating electric machines mounted on various machines, such as air conditioners.

[0083] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments. [Explanation of symbols]

[0084] 10... stator, 11... stator core, 12... coil, 13... heat transfer body, 13a... outer peripheral surface, 13b... bottom surface, 20... rotor, 21... rotor core, 22... permanent magnet, 23... heat transfer body, 33... heat transfer body, 43... heat transfer body, 100... rotating electric machine, 111... yoke portion, 112... teeth, 112a... axial end surface, 113... slot, 120... concentrated winding coil, 121... coil end, 121a... inner peripheral surface, 130... conductive member, 131b to 135b... core contact surface, 140... insulating layer, 230... conductive member, 330... conductive member, 331b, 334b... core contact surface, 430... conductive member, Ca... rotation central axis

Claims

1. A rotating electric machine including a stator and a rotor rotatably provided relative to the stator, The stator includes a stator core having a cylindrical yoke portion and a plurality of teeth protruding from the yoke portion, a coil wound around the plurality of teeth, and a heat transfer body that transfers heat of the coil to the stator core, The coil has a coil end protruding from the stator core in the axial direction thereof, the heat transfer body is disposed so as to be in contact with an inner peripheral surface of the coil end and the stator core, The heat transfer body includes a plurality of conductive members arranged along a direction perpendicular to a radial direction of the stator core, and an insulating layer formed between the plurality of conductive members, The plurality of conductive members are arranged along the axial direction of the stator core, The thickness of the conductive member disposed on the axially outer side of the stator core is thinner than the thickness of the conductive member disposed on the axially inner side of the stator core. A rotating electric machine characterized by:

2. A rotating electric machine comprising a stator and a rotor rotatably provided with respect to the stator, The stator includes a stator core having a cylindrical yoke portion and a plurality of teeth protruding from the yoke portion, a coil wound around the plurality of teeth, and a heat transfer body that transfers heat of the coil to the stator core, The coil has a coil end protruding from the stator core in the axial direction thereof, the heat transfer body is disposed so as to be in contact with an inner peripheral surface of the coil end and the stator core, The heat transfer body includes a plurality of conductive members arranged along a direction perpendicular to a radial direction of the stator core, and an insulating layer formed between the plurality of conductive members, the plurality of conductive members include a pair of conductive members formed in a symmetrical shape with respect to a center plane of the heat transfer body in a circumferential width of the stator core, The pair of conductive members are adjacent to each other in the circumferential direction of the stator core. A rotating electric machine characterized by:

3. 3. The rotating electric machine according to claim 1, The plurality of conductive members includes a conductive member formed along an inner peripheral surface of the coil end. A rotating electric machine characterized by:

4. 3. The rotating electric machine according to claim 1, The plurality of conductive members are formed so that each has an equal cross-sectional area perpendicular to the radial direction of the stator core. A rotating electric machine characterized by:

5. 2. The rotating electric machine according to claim 1, the plurality of conductive members include a pair of conductive members formed in a symmetrical shape with respect to a center plane of the heat transfer body in a circumferential width of the stator core, The pair of conductive members are adjacent to each other in the circumferential direction of the stator core. A rotating electric machine characterized by:

6. 3. The rotating electric machine according to claim 1, The plurality of conductive members constituting the heat transfer body are formed of a non-magnetic material. A rotating electric machine characterized by:

7. 3. The rotating electric machine according to claim 1, All of the plurality of conductive members constituting the heat transfer body have contact surfaces that come into surface contact with the stator core. A rotating electric machine characterized by:

8. 3. The rotating electric machine according to claim 1, The thermal conductivity of the plurality of conductive members constituting the heat transfer body is higher than the thermal conductivity in the axial direction of the stator core. A rotating electric machine characterized by:

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