Patent ID: 12218570

DESCRIPTION OF EMBODIMENTS

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 the present embodiment is a rotating electric machine suitable to be used for traveling of a vehicle. The rotating electric machine according to the present embodiment can be applied to both a pure electric vehicle that travels only by the rotating electric machine and a hybrid electric vehicle that is driven by both an engine and the rotating electric machine. The rotating electric machine is an induction motor including a squirrel-cage rotor or is a synchronous motor including a rotor having a permanent magnet. Hereinafter, a synchronous motor used in a hybrid electric vehicle will be described as an example.

FIG.1is a diagram illustrating a schematic configuration of a hybrid electric vehicle equipped with the rotating electric machine according to the embodiment of the present invention. The electric vehicle (also referred to as a vehicle) includes an engine ENG, a first rotating electric machine100A, and a second rotating electric machine100B. The first rotating electric machine100A and the second rotating electric machine100B are also collectively referred to as a rotating electric machine100. Power generated by the engine ENG and the first rotating electric machine100A is shifted by a transmission TM and transmitted to front wheels FW. Power generated by the second rotating electric machine100B is transmitted to rear wheels RW.

The rotating electric machine100performs a power running operation for generating a driving force and a regenerative operation for recovering energy according to a traveling state of the vehicle. Drive and power generation operations of the rotating electric machine100are controlled by a power conversion device INV such that the torque and the rotation speed are optimized according to the operation status of the vehicle. Power necessary for driving the rotating electric machine100is supplied from a battery BAT via the power conversion device INV. When the rotating electric machine100is in the power generation operation, the battery BAT is charged with electric energy via the power conversion device INV.

The structure of the rotating electric machine100will be described with reference to the drawings. Since the first rotating electric machine100A and the second rotating electric machine100B have substantially the same structure, the structure of the first rotating electric machine100A will be described below as a representative example. Note that the structure described below is not necessarily employed in both the first rotating electric machine100A and the second rotating electric machine100B, and may be employed in only one of them. In the following description, an “axial direction”, a “circumferential direction”, and a “radial direction” are as follows. The “axial direction” is a direction along the rotation center axis Ca of the rotating electric machine100(a rotor150). The rotation center axis Ca coincides with the center axis of a cylindrical stator130. The “circumferential direction” is a direction along the rotation direction of the rotating electric machine100(the rotation direction of the rotor150), that is, a circumferential direction orthogonal to the rotation center axis Ca and centered on the rotation center axis Ca. The “radial direction” is a radiation direction perpendicular to the rotation center axis Ca of the rotating electric machine100and centered on the rotation center axis Ca, that is, a radius direction. In addition, the “inner peripheral side” refers to the radially inner side (inner diameter side), and the “outer peripheral side” refers to the opposite direction, that is, the radially outer side (outer diameter side).

FIG.2is a side sectional view illustrating a configuration of the rotating electric machine100according to the embodiment of the present invention.FIG.2illustrates the inside of the rotating electric machine100by illustrating a part of the rotating electric machine100in a cross section.FIG.3is a perspective view of the rotating electric machine100, and omits illustration of a case110.FIG.4is a plan cross-sectional view of a stator core132and a rotor core152, and illustrates a cross section of the rotating electric machine100as viewed from the axial direction.

As illustrated inFIG.2, the rotating electric machine100includes the rotor150rotatably provided, the stator130disposed outside with an air gap between the stator130and the rotor150in the radial direction, and the case110that supports (fixes) the stator130.

The rotating electric machine100is a permanent-magnet-embedded three-phase synchronous motor generator. The rotating electric machine100operates as an electric motor that rotates the rotor150by supplying a three-phase alternating current to a stator coil138wound around the stator core132. The rotating electric machine100is driven by the engine ENG to operate as a generator and output generated power of three-phase alternating current.

The case110includes a case body112and an end bracket111. The case body112is a bottomed cylindrical member having one end opened, and has a cylindrical portion113and a bottom portion114. The end bracket111is attached to the case body112so as to close the opening of the case body112(the opening of the cylindrical portion113). Insertion holes111aand114athrough which a shaft118is inserted are provided in the end bracket111and the bottom portion114of the case body112. A first bearing14A is provided in the insertion hole111aof the end bracket111, and a second bearing14B is provided in the insertion hole114aof the bottom portion114of the case body112. The case110may be constituted by a center bracket whose both axial ends are opened and a pair of end brackets axially sandwiching the center bracket. In other words, the cylindrical portion113and the bottom portion114of the case body112may be provided as separate members, and the two members may be connected by a bolt or the like.

The case110is provided with an attachment portion110ato be attached to a support member9of the vehicle body of the vehicle. The support member9of the vehicle body is, for example, a support member provided in the case of the transmission TM, a support member provided in the case of the engine ENG, or a support member provided between the transmission TM and the engine ENG. The rotating electric machine100is attached to the vehicle by fastening the attachment portion110ato the support member9with a bolt or the like. The case110may constitute a part of the case of the transmission TM or a part of the case of the engine ENG.

The rotor150is fixed to the shaft118. The shaft118is a columnar or cylindrical member. When the shaft118is supported by the first bearing14A and the second bearing14B, the rotor150is rotatably held inside the stator core132. The rotor150is disposed such that the rotation center axis Ca is horizontal. That is, the attachment portion110aof the case110is formed such that the rotation center axis Ca is set to be horizontal when the attachment portion110ais attached to the support member9.

In the cylindrical portion113of the case body112, a refrigerant passage121as a flow path through which a liquid refrigerant flows is formed. That is, the case body112is a flow path forming member forming the refrigerant passage121. In the present embodiment, the refrigerant passage121has a rectangular cross-sectional shape having a width (axial length) larger than a height (radial length), and is formed in a spiral shape along the circumferential direction of the cylindrical portion113.

The refrigerant is oil having a kinematic viscosity of 4 to 24 [mm2/s] at 100° C. In the present embodiment, the refrigerant is an automatic transmission fluid (ATF) used for lubrication and cooling of components (power transmission unit and the like) in the transmission TM.

The refrigerant is sucked by a pump (not illustrated) from a refrigerant reservoir (not illustrated) in the lower portion of the rotating electric machine100, flows out from a first outflow hole122A and a second outflow hole122B (seeFIG.10) formed in the upper portion of the case110via the refrigerant passage121, and returns to the refrigerant reservoir. In the rotating electric machine100, the stator coil138is a main heat generating portion, and heat generated in the stator coil138is transmitted to the case110via the stator core132and dissipated by the refrigerant flowing through the refrigerant passage121of the case110. In the present embodiment, the stator coil138is directly cooled by dropping the refrigerant from the first outflow hole122A and the second outflow hole122B to a coil end139of the stator coil138and causing the refrigerant to adhere to the coil end139. Details of the first outflow hole122A and the second outflow hole122B will be described later. Although not illustrated, the refrigerant is cooled by an air-cooling type or water-cooling type heat exchanger (oil cooler).

As illustrated inFIGS.2and3, the stator130includes the cylindrical stator core132and the stator coil138attached to the stator core132. As illustrated inFIG.4, a plurality of (72in the present embodiment) slots133parallel to the central axis direction of the stator core132is formed in the inner peripheral portion of the stator core132, and a plurality of U-phase, V-phase, and W-phase phase windings constituting the stator coil138(seeFIGS.2,3, and5) is attached to the slots133. The plurality of slots133is formed at equal intervals in the circumferential direction of the stator core132.

Teeth134are formed between the slots133. In the present embodiment, the plurality of teeth134is integrated with an annular core back135. That is, the stator core132is an integrated core in which the plurality of teeth134and the core back135are integrally molded. The teeth134form a magnetic path in the radial direction, and the core back135forms a magnetic path in the circumferential direction. The teeth134guide a rotating magnetic field generated by the stator coil138to the rotor150, and cause the rotor150to generate rotational torque.

The stator core132is formed, for example, by laminating a plurality of electromagnetic steel sheets having an annular shape. The stator core132is fitted and fixed to the inside of the cylindrical portion (seeFIG.2)113by shrink fitting, press fitting, or the like.

As illustrated inFIGS.2and4, the rotor150includes the rotor core152and a plurality of permanent magnets154fixed to the rotor core152. The rotor core152is formed, for example, by laminating a plurality of electromagnetic steel sheets having an annular shape. The permanent magnets154form a field pole of the rotor150. As each of the permanent magnets154, a neodymium-based or samarium-based sintered magnet, a ferrite magnet, a neodymium-based bonded magnet, or the like can be used.

In the rotor core152, rectangular parallelepiped magnet insertion holes are formed at equal intervals in the circumferential direction in the vicinity of the outer peripheral portion, and the permanent magnet154is embedded in each magnet insertion hole and fixed with an adhesive or the like. The circumferential width of the magnet insertion hole is larger than the circumferential width of the permanent magnet154. A magnetic gap156is formed between both circumferential ends of the permanent magnet154and both circumferential ends of the magnet insertion hole. An adhesive may be embedded in the magnetic gap156, or the magnetic gap may be fixed integrally with the permanent magnets154with a resin.

The magnetization direction of the permanent magnets154is directed in the radial direction, and the magnetization direction is reversed for each field pole. That is, assuming that the surface on the stator130side of the permanent magnet154for forming a certain magnetic pole is magnetized to the N pole and the surface on the shaft118side is magnetized to the S pole, the surface on the stator130side of the permanent magnet154forming the adjacent magnetic pole is magnetized to the S pole, and the surface on the shaft118side is magnetized to the N pole.

In the present embodiment, an auxiliary magnetic pole159is formed between the permanent magnets154forming a magnetic pole. The auxiliary magnetic pole159acts so as to reduce the magnetic resistance of a q-axis magnetic flux generated by the stator coil138. The auxiliary magnetic pole159makes the magnetic resistance of the q-axis magnetic flux much smaller than the magnetic resistance of the d-axis magnetic flux, so that a large reluctance torque is generated.

The stator coil138will be described with reference toFIGS.2and5to8.FIG.5is a perspective view illustrating the stator coil138for three phases.FIG.6Ais a perspective view of a U-phase stator coil138wound around the stator core132, and illustrates U1-phase and U2-phase stator coils138.FIG.6Bis a perspective view of the U1-phase stator coil138wound around the stator core132. The stator coil138is wound around the stator core132in distributed winding (wave winding). The distributed winding is a winding method in which phase windings are wound around the stator core132such that the phase windings are housed in two slots133separated across a plurality of slots133.

The stator coil138includes intra-slot conductors137disposed in the slots133of the stator core132, and coil ends139which are extra-slot conductors disposed to protrude from both ends of the stator core132to the outside of the slots133. For the stator coil138, a rectangular wire (seeFIG.7(d)) in which the rectangular cross section of the stator coil138is longer in the radial direction than in the circumferential direction is used in each slot133. The outer periphery of the rectangular wire is covered with an insulating film.

As illustrated inFIGS.6A,6B, and7, the stator coil138is a segment type coil formed by connecting a plurality of U-shaped segment conductors140to each other. As illustrated inFIGS.6A and6B, in each of the segment conductors140, the central portion140cconstitutes the coil end139on one side in the axial direction of the stator130, and the end portions140eon both sides are welded to constitute the coil end139on the other side in the axial direction of the stator130.

As illustrated inFIG.5, a total of six systems (U1, U2, V1, V2, W1, and W2) of coils of the stator coil138are attached in close contact with the stator core132. The coils of six systems constituting the stator coil138are arranged at appropriate intervals from each other by the slots133.

AC terminals41(U),42(V), and43(W), which are coil conductors for input/output of the stator coils138of the three UVW phases, and neutral point connection conductors40are led out to one coil end139of the stator coil138. The stator130is connected to the power conversion device INV via the AC terminals41(U),42(V), and43(W). The neutral point connection conductors40are disposed on both sides of the AC terminals41(U),42(V), and43(W). The neutral point connection conductors40include a U1-phase neutral line at the end of winding of the U1phase, a V1-phase neutral line at the end of winding of the V1phase, and a W1-phase neutral line at the end of winding of the W1phase, and are welded in advance. The same applies to the U2, V2, and W2phases.

FIG.7is a schematic view for explaining a step of attaching the segment conductors140to the stator core132. InFIG.7(d), illustration of an insulating paper (slot liner) disposed between the segment conductors140and the slots133is omitted.FIG.8is a schematic view for explaining the positions of the segment conductors140inserted in the slots133of the stator core132. In the present embodiment, 12 slots133are arranged at an electrical angle of 360 degrees, and for example, slot numbers 01 to 12 inFIG.8correspond to two poles. Therefore, the number of slots per pole is 6, and the number of slots per phase per pole NSPP is 2 (=6/3). Four segment conductors140of the stator coil138are inserted in each slot133. In each of rectangular frames representing the segment conductors140, a cross mark “x” indicating a direction from one side to the opposite side of the stator core132or a black circle mark “•” indicating the opposite direction is written. The U-phase segment conductors140are denoted by reference signs U11to U24representing round windings, and the V-phase and W-phase segment conductors140are denoted by reference signs V and W representing the phases.

As illustrated inFIG.7(a), the segment conductor140is formed in a substantially U shape having a pair of leg portions141aand141bextending linearly and a top portion142connecting the pair of leg portions141aand141b. The top portion142has a pair of inclined portions143aand143band a bent portion144that connects the pair of inclined portions143aand143b. Bent portions145in which the conductor is bent are formed between both ends of the top portion142and the pair of leg portions141aand141b. That is, the top portion142and the leg portions141aand141bare connected by the bent portions145. The inclined portions143aand143bare inclined at a predetermined angle with respect to the leg portions141aand141bparallel to the axial direction.

When the segment conductors140are connected to each other to form each phase winding, as illustrated inFIG.7(a), the pair of leg portions141aand141bof the segment conductor140is inserted into different slots133from one side in the axial direction of the stator core132. Thereafter, as illustrated inFIG.7(b), the leg portions141aand141bprotruding to the other side in the axial direction of the stator core132are bent in directions where the segment conductor is to be connected, and as illustrated inFIG.7(c), the end portions140eof the leg portions141aand141bare welded to the end portions140eof another segment conductor140.

A portion connecting the segment conductors140is referred to as a connection portion149. The connection portion149has a pair of inclined portions147aand147band an end portion140eprovided in each of the inclined portions147aand147b. The end portion140eis formed by bending a distal end portion of the inclined portion147aso as to be parallel to the axial direction. The inclined portions143aand143bare connected to the leg portions141aand141bvia bent portions146. The bent portions146are formed by bending the end portions of the pair of leg portions141aand141boutward in the circumferential direction such that the end portions of the pair of leg portions141aand141bare further apart from each other. Similarly to the inclined portions143aand143b, the inclined portions147aand147bare inclined at a predetermined angle with respect to straight portions of the leg portions141aand141bparallel to the axial direction. Insulating films at the end portions140eare removed before welding.

When each segment conductor140is welded at the end portions140eand attached to the stator core132as the stator coil138, as illustrated inFIG.7(d), the straight portions of the pair of leg portions141aand141bof each segment conductor140are disposed in the slots133. Therefore, the straight portions of the leg portions141aand141barranged in the slots133correspond to the intra-slot conductors137of the stator coil138.

As illustrated inFIG.8, a plurality of (four) intra-slot conductors137is arranged in layers in each slot133of the stator core132. In the present embodiment, four conductor insertion spaces are provided in each slot133. The conductor insertion spaces are referred to as a first layer (L1), a second layer (L2), a third layer (L3), and a fourth layer (L4) in order from an inner peripheral side (lower side in the drawing) to an outer peripheral side (upper side in the drawing) in the radial direction. As illustrated inFIG.7(d), the segment conductors140include one in which one leg portion141bof the pair of leg portions141aand141bis inserted into the first layer (L1) and the other leg portion141ais inserted into the second layer (L2), and one in which one leg portion141bof the pair of leg portions141aand141bis inserted into the third layer (L3) and the other leg portion141ais inserted into the fourth layer (L4).

As illustrated inFIG.2, the coil end (extra-slot conductor)139which protrudes to the outside on one side (left side in the drawing) in the axial direction of the stator core132and is exposed from the stator core132and has a top portion142(seeFIG.7) is also referred to as a bent coil end139B.

The coil end (extra-slot conductor)139which protrudes to the outside on the other side (right side in the drawing) in the axial direction of the stator core132and is exposed from the stator core132and has a connection portion149(seeFIG.7) is also referred to as a welded coil end139A. As illustrated inFIG.3, since the coil ends139are disposed so as to overlap each other in the circumferential direction of the stator core132, the axial length of the rotating electric machine100can be shortened.

The outflow holes122A and122B through which the refrigerant flows out toward the coil ends139will be described in detail with reference toFIGS.9and10.FIGS.9and10are a plan view (top view) of the rotating electric machine100in a state of being attached to the vehicle body and a side view (partial cross-sectional view) of the rotating electric machine100in a state of being attached to the vehicle body as viewed from the axial direction.FIG.9is a view illustrating the rotating electric machine100as viewed from the IX direction inFIG.2. InFIG.9, the case body112is indicated by a two-dot chain line, and a part of the welded coil end139A is enlarged.FIG.10is a view of the welded coil end139A as viewed from the axial direction.FIG.10illustrates a cross section of the case110taken along line X-X inFIG.2, and illustrates the first outflow hole122A and the second outflow hole122B in an enlarged manner.

As illustrated inFIG.9, the first outflow hole122A and the second outflow hole122B are provided on each of one axial end side (the bent coil end139B side) and the other axial end side (the welded coil end139A side) of the case body112. Note that there are only two refrigerant outflow holes in total, that is, the first outflow hole122A and the second outflow hole122B on one end side of the case body112in the axial direction, and there is no refrigerant outflow hole through which the refrigerant drops toward the bent coil end139B side other than the first outflow hole122A and the second outflow hole122B. Similarly, there are only two refrigerant outflow holes in total, that is, the first outflow hole122A and the second outflow hole122B on the other end side of the case body112in the axial direction, and there is no refrigerant outflow hole through which the refrigerant drops toward the welded coil end139A other than the first outflow hole122A and the second outflow hole122B. The first outflow hole122A and the second outflow hole122B are provided on each of one axial end side (the bent coil end139B side) and the other axial end side (the welded coil end139A side) of the case body112, and have the same configuration. Therefore, hereinafter, the first outflow holes122A and the second outflow hole122B through which the refrigerant drops toward the welded coil end139A will be described as representatives.

FIGS.9and10illustrate a state in which the attachment portion110aof the case110is attached to the support member9of the vehicle body (seeFIG.2) and the case110is installed at a predetermined position in the vehicle body. As illustrated inFIGS.9and10, in a state where the case110is installed, the first outflow holes122A and the second outflow holes122B are disposed above the coil ends139. The first outflow holes122A and the second outflow holes122B are through-holes having a circular cross section and penetrating in the radial direction from the inner peripheral surface115of the case110(cylindrical portion113) through the refrigerant passage121and communicating with the inner space of the case110and the refrigerant passage121. The first outflow holes122A and the second outflow holes122B allow the refrigerant to flow out from the refrigerant passage121toward the coil ends139.

As illustrated inFIG.9, the conductor (inclined portion147a) constituting the outermost peripheral portion of the welded coil end139A is bent toward one side in the circumferential direction at the bent portion146with respect to the intra-slot conductor137(leg portion141a). The conductor (inclined portion143a) constituting the outermost peripheral portion of the bent coil end139B is bent toward the other side in the circumferential direction at the bent portion145with respect to the intra-slot conductor137(leg portion141a).

In the following description, a bending direction of the extra-slot conductor with respect to the intra-slot conductor in the conductor constituting the outermost peripheral portion of the coil end139disposed on the upper portion of the stator130is referred to as an upper coil bending direction. More specifically, the upper coil bending direction is a bending direction of the extra-slot conductor (corresponding to the inclined portions143aand147aof the segment conductor140illustrated inFIG.7) with respect to the intra-slot conductor (corresponding to the straight portion of the leg portion141aof the segment conductor140illustrated inFIG.7) arranged on the outermost diameter side in the slot133in the stator coil138(see the enlarged view) arranged at the upper portion (for example, the top portion) of the stator130when the stator130is viewed from above. That is, the upper coil bending direction in the welded coil end139A is the bending direction of the inclined portion147awith respect to the leg portion141ain the segment conductor140, and the upper coil bending direction in the bent coil end139B is the bending direction of the inclined portion143awith respect to the leg portion141ain the segment conductor140. Therefore, the upper coil bending direction Da of the welded coil end139A is the left direction in the drawing, and the upper coil bending direction Db of the bent coil end139B is the right direction in the drawing. As illustrated inFIG.10, a straight line (vertical line) that is perpendicular to the horizontal and passes through the rotation center axis Ca is defined as a vertical line VL.

As illustrated inFIGS.9and10, the first outflow hole122A is disposed on the upper coil bending direction Da side (left side in the drawing) with respect to the vertical line VL, and the second outflow hole122B is disposed on the opposite side (right side in the drawing) to the upper coil bending direction Da with respect to the vertical line VL. As illustrated inFIG.10, in a coordinate system in which the rotation center axis Ca is the origin, a horizontal line (a line parallel to a horizontal plane) HL passing through the rotation center axis Ca is an X axis, and a vertical line VL is a Y axis, when divided into a first quadrant, a second quadrant, a third quadrant, and a fourth quadrant in a counterclockwise direction (that is, one circumferential direction in which the extra-slot conductor (inclined portion147a) is inclined with respect to the intra-slot conductor137(leg portion141a) arranged in the fourth layer L4) as illustrated, the first outflow hole122A is arranged in the second quadrant, and the second outflow hole122B is arranged in the first quadrant.

As described above, the extra-slot conductor (inclined portion147a) protruding from the slot133of the stator core132is bent toward one side in the circumferential direction (counterclockwise direction in the drawing) with respect to the intra-slot conductor137. The refrigerant dropped from the first outflow hole122A and the second outflow hole122B to the outermost peripheral portion of the coil end139flows along the coil conductor (inclined portion147a) of the outermost peripheral portion. For this reason, if the first outflow hole122A and the second outflow hole122B are disposed symmetrically with respect to the vertical line VL, there is a possibility that non-uniformness occurs in the adhesion range of the refrigerant to the coil end139. Therefore, in the present embodiment, by arranging the first outflow hole122A and the second outflow hole122B asymmetrically with respect to the vertical line VL, non-uniformness in the adhesion range of the refrigerant is reduced.

As illustrated inFIG.10, the first outflow hole122A and the second outflow hole122B are formed such that an arrangement angle (hereinafter, also referred to as a second arrangement angle θb) of the second outflow hole122B is larger than an arrangement angle (hereinafter, also referred to as a first arrangement angle θa) of the first outflow hole122A with reference to the vertical line VL. The first arrangement angle θa corresponds to an angle (acute angle) formed by a straight line (line segment) La connecting the center of the refrigerant outlet portion of the first outflow hole122A and the rotation center axis Ca and a half straight line extending upward from the rotation center axis Ca on the vertical line VL. The second arrangement angle θb corresponds to an angle (acute angle) formed by a straight line (line segment) Lb connecting the center of the refrigerant outlet portion of the second outflow hole122B and the rotation center axis Ca and the half straight line extending upward from the rotation center axis Ca on the vertical line VL. That is, the closer the first arrangement angle θa and the second arrangement angle θb are to the vertical line VL, the smaller the first arrangement angle θa and the second arrangement angle θb become.

In other words, as illustrated inFIG.9, the first outflow hole122A and the second outflow hole122B are formed such that a horizontal distance Xb between the center of the refrigerant outlet portion of the second outflow hole122B and the rotation center axis Ca (or the vertical line VL) is larger than a horizontal distance Xa between the center of the refrigerant outlet portion of the first outflow hole122A and the rotation center axis Ca (or the vertical line VL).

As illustrated inFIG.10, in the present embodiment, the first arrangement angle θa is 30 degrees, and the second arrangement angle θb is 40 degrees. The first arrangement angle θa and the second arrangement angle θb can be set to various angles according to the kinematic viscosity of the refrigerant, but it is preferable to set the first arrangement angle θa and the second arrangement angle θb such that an angle difference Δθ (θb−θa) between the first arrangement angle θa and the second arrangement angle θb is at least equal to or larger than a slot pitch angle (in the present embodiment, 360/72=5 degrees). When the first outflow hole122A and the second outflow hole122B are provided at positions close to the horizontal line HL (X axis), the upper portion of the coil end139cannot be effectively cooled. Therefore, the first arrangement angle θa and the second arrangement angle θb are preferably set to 45 degrees or less. Therefore, it is preferable to set the first arrangement angle θa and the second arrangement angle θb such that the angle difference Δθ between the first arrangement angle θa and the second arrangement angle θb is 5 degrees or more and 15 degrees or less.

As illustrated inFIG.9, the first outflow hole122A and the second outflow hole122B are provided at positions overlapping the coil end139when the stator130is viewed from above (directly above). That is, the coil end139is disposed on the vertical axis passing through the refrigerant outlet portions of the first outflow hole122A and the second outflow hole122B. The first outflow hole122A and the second outflow hole122B are formed at positions closer to the end surface132aof the stator core132than to the axial end of the coil end139. That is, the axial distance Z1from the centers of the refrigerant outlet portions of the first outflow hole122A and the second outflow hole122B to the end surface132aof the stator core132is shorter than the axial distance Z2from the centers of the refrigerant outlet portions of the first outflow hole122A and the second outflow hole122B to the axial end of the coil end139(Z1<Z2). The axial distance Z2is a distance between the centers of the refrigerant outlet portions of the first outflow hole122A and the second outflow hole122B and the tip of the end portion140ein the welded coil end139A, and is a distance between the centers of the refrigerant outlet portions of the first outflow hole122A and the second outflow hole122B and the tip of the bent portion144in the bent coil end139B. In this manner, by forming the first outflow holes122A and the second outflow holes122B closer to the stator core132, not only the coil ends139but also the end surface132aof the stator core132can be effectively cooled by the refrigerant.

FIG.11Ais a diagram illustrating an adhesion range of the refrigerant to the welded coil end139A in the rotating electric machine100according to the present embodiment, andFIG.11Bis a diagram illustrating an adhesion range of a refrigerant to a welded coil end139A in a rotating electric machine900according to a comparative example of the present embodiment.FIGS.11A and11Bare schematic side views of the rotating electric machines when the welded coil ends139A are viewed from the axial direction. The rotating electric machine900according to the comparative example of the present embodiment is different from the rotating electric machine100according to the present embodiment only in the position of a second outflow hole922B. In the rotating electric machine900according to the comparative example, a first outflow hole122A and the second outflow hole922B are provided line-symmetrically with respect to the vertical line VL.

InFIGS.11A and11B, non-adhesion ranges191,192,991, and992, which are ranges where the refrigerant does not adhere, obtained from the result of a computer simulation performed under the same condition are schematically indicated by hatched portions (shaded portions). As illustrated inFIGS.11A and11B, the simulation confirms that the non-adhesion ranges191,192,991, and992are present on upper portions and side portions (right portions in the drawing) of the coil ends139in both the rotating electric machine100and the rotating electric machine900. That is, it has been confirmed that, in each of the rotating electric machine100and the rotating electric machine900, the adhesion range of the refrigerant to the right portion of the coil end139in the drawing is smaller than that on the left portion of the coil end139in the drawing, and non-uniformness occurs in the adhesion range of the refrigerant to the left and right side portions of the coil end139.

The non-adhesion range191on the upper portion of the welded coil end139A according to the present embodiment is larger than the non-adhesion range991on the upper portion of the welded coil end139A according to the comparative example, but the non-adhesion range192on the side portion of the welded coil end139A according to the present embodiment is smaller than the non-adhesion range992on the side portion of the welded coil end139A according to the comparative example. Since the difference between the non-adhesion range192and the non-adhesion range992on the side portions of the coil ends139is larger than the difference between the non-adhesion range191and the non-adhesion range991on the upper portions of the coil ends139, the total non-adhesion area of the rotating electric machine100according to the present embodiment is smaller than the total non-adhesion area of the rotating electric machine900according to the comparative example.

In the present embodiment, it has been confirmed by simulation that the total adhesion range of the refrigerant to the coil end139of the rotating electric machine100is about 20% larger than the total adhesion range of the refrigerant to the coil end139of the rotating electric machine900.

As illustrated inFIG.9, since the upper coil bending direction Da of the welded coil end139A is the left direction, the refrigerant dropped on the welded coil end139A easily flows toward the left direction. Therefore, as illustrated inFIG.11B, in the rotating electric machine900in which the first outflow hole122A and the second outflow hole922B are disposed symmetrically with respect to the vertical line VL, the refrigerant flowing out from the second outflow hole922B easily flows toward the left direction along the conductor of the outermost peripheral portion of the welded coil end139A, and the non-adhesion range992on the right side is large (seeFIG.11A). That is, in the comparative example, the range in which the refrigerant adheres on the side opposite to the upper coil bending direction Da is smaller than the range in which the refrigerant adheres on the upper coil bending direction Da side with reference to the vertical line VL, and the adhesion range is significantly non-uniform in the left and right portions.

On the other hand, in the present embodiment, as compared with the comparative example, since the second outflow hole122B is disposed at a position shifted in the direction opposite to the upper coil bending direction Da (that is, the direction in which the refrigerant is guided) from the line symmetrical position of the first outflow hole122A with reference to the vertical line VL, the non-adhesion range192on the right side portion of the welded coil end139A can be reduced, and non-uniformness in the adhesion range of the refrigerant to the left and right side portions of the welded coil end139A can be suppressed as compared with the comparative example. Therefore, according to the present embodiment, the adhesion area of the refrigerant to the entire welded coil end139A can be increased, and the welded coil end139A can be effectively cooled.

Although the welded coil end139A has been described as a representative, the first outflow hole122A and the second outflow hole122B through which the refrigerant drops onto the bent coil end139B also have the same configuration. As illustrated inFIG.9, the upper coil bending direction Db in the bent coil end139B is the right direction in the drawing, and is opposite to the upper coil bending direction Da in the welded coil end139A. Therefore, when the rotating electric machine100is viewed from above, the first outflow hole122A and the second outflow hole122B on the bent coil end139B side are disposed opposite to the first outflow hole122A and the second outflow hole122B on the welded coil end139A side in the left-right direction.

According to the embodiment described above, the following operational effects are obtained.

(1) The rotating electric machine100includes a rotor150disposed such that a rotation center axis Ca is horizontal, a stator130disposed with an air gap between the rotor150and the stator130in a radial direction, and a case110that supports the stator130and forms a refrigerant passage (flow path)121through which a refrigerant flows.

The stator130includes a stator core132having a plurality of slots133and a stator coil138attached to the stator core132. The stator coil138includes an intra-slot conductor137disposed in the slot133of the stator core132and a coil end (extra-slot conductor)139disposed outside the slot. The case110forms a first outflow hole122A and a second outflow hole122B through which the refrigerant flows out toward the coil end (extra-slot conductor)139. In a state where the case110is installed, the first outflow hole122A and the second outflow hole122B are arranged above the coil end (extra-slot conductor)139, and when a bending direction of the coil end (extra-slot conductor)139with respect to the intra-slot conductor137arranged on the outermost diameter side in the slot133in the stator coil138arranged above the stator130is an upper coil bending direction, and a straight line perpendicular to the horizontal and passing through the rotation center axis Ca is a vertical line VL, the first outflow hole122A is arranged on the upper coil bending direction side with respect to the vertical line VL, and the second outflow hole122B is arranged on a side opposite to the upper coil bending direction with respect to the vertical line VL. The first outflow hole122A and the second outflow hole122B are formed such that a second arrangement angle θb that is an angle formed by a straight line Lb connecting the second outflow hole122B and the rotation center axis Ca and the vertical line VL is larger than a first arrangement angle θa that is an angle formed by a straight line La connecting the first outflow hole122A and the rotation center axis Ca and the vertical line VL.

As described above, in the present embodiment, the second outflow hole122B is disposed at a position shifted in the direction opposite to the upper coil bending directions (that is, the direction in which the refrigerant is guided) Da and Db from the line symmetrical position of the first outflow hole122A with reference to the vertical line VL. Therefore, the range of the adhesion to the side portion of the coil end139on the side opposite to the upper coil bending directions Da and Db can be increased. As a result, it is possible to suppress non-uniformness in the adhesion range of the refrigerant to the left and right side portions of the coil end139with reference to the vertical line VL, to increase the adhesion area of the refrigerant to the entire coil end139, and to effectively cool the stator coil138. According to the present embodiment, since the current supplied to the stator coil138can be increased by improving the cooling performance, the output of the rotating electric machine100can be improved and the efficiency can be improved.

(2) The first outflow hole122A and the second outflow hole122B are formed at positions closer to an end surface132aof the stator core132than to an axial end of the coil end (extra-slot conductor)139. By disposing the first outflow hole122A and the second outflow hole122B closer to the stator core132than to the axial end of the coil end139, it is possible to cool the coil end139while cooling the end surface132aof the stator core132. That is, according to this configuration, the end portion of the stator core132can be effectively cooled.

(3) The refrigerant is oil having a kinematic viscosity of 4 to 24 [mm2/s] at 100° C. Therefore, it is possible to effectively cool the stator coil138by directly cooling the coil end139while suppressing corrosion of the coil end139.

(4) An angle difference Δθ between the first arrangement angle θa and the second arrangement angle θb is 5 degrees or more and 15 degrees or less. As a result, it is possible to effectively increase the adhesion range of the refrigerant to the side portion of the coil end139while suppressing a decrease in the adhesion range of the refrigerant to the upper portion of the coil end139.

The following modifications are also within the scope of the present invention, and it is also possible to combine configurations indicated in the modifications with the configuration described in the above-described embodiment, and combine the configurations described in the following different modifications.

Modification 1

In the above embodiment, an example in which the first outflow holes122A and the second outflow holes122B are formed near the end surface132aof the stator core132has been described. However, the first outflow holes and the second outflow holes may be formed near the axial ends of the coil ends139. As described above, by forming the first outflow holes122A and the second outflow holes122B near the end surface132aof the stator core132, the end surface132aof the stator core132can be directly cooled by the refrigerant together with the coil end139, which is preferable.

Modification 2

In the above embodiment, an example has been described in which the cross-sectional shapes (the shape of the flow path cross section orthogonal to the flow of the refrigerant) of the first outflow holes122A and the second outflow holes122B are circular, but the present invention is not limited thereto. For example, the cross-sectional shapes of each of the first outflow holes122A and the second outflow holes122B may be an elliptical shape, a polygonal shape, or an irregular shape.

Modification 3

In the above embodiment, an example in which the stator coil138is a rectangular wire having a rectangular cross-sectional shape has been described, but the present invention is not limited thereto. The cross-sectional shape of the stator coil138may be a polygonal shape such as a triangular shape and a pentagonal shape, a circular shape, an elliptical shape, or an irregular shape.

Modification 4

In the above embodiment, an example has been described in which the first outflow hole122A and the second outflow hole122B are provided on each of the one axial end side (the bent coil end139B side) and the other axial end side (the welded coil end139A side) of the case body112, but the present invention is not limited thereto. The first outflow hole122A and the second outflow hole122B may be provided only on one axial end side (the bent coil end139B side) of the case body112, or the first outflow hole122A and the second outflow hole122B may be provided only on the other axial end side (the welded coil end139A side) of the case body112.

Modification 5

The arrangement configuration of the segment conductors140(seeFIG.8) is not limited to that described in the above embodiment. The number of the slots133of the stator core132is not limited to that described in the above embodiment.

Modification 6

In the above embodiment, an example in which the four layers (L1, L2, L3, L4) are formed in the slots133has been described, but the present invention is not limited thereto. For example, the present invention may be applied to a rotating electric machine including a stator in which two layers are formed in slots133or a stator in which six or more layers are formed.

Modification 7

In the above embodiment, an example in which the stator coil138is wound around the stator core132in wave winding has been described, but the present invention is not limited thereto. The present invention may be applied to a rotating electric machine in which a stator coil138is wound around a stator core132in lap winding.

Modification 8

In the above embodiment, an example in which the rotating electric machine100is mounted on a vehicle has been described, but the present invention is not limited thereto. The present invention can be applied to a case where the rotating electric machine100is installed in a machine such that the rotation center axis Ca is horizontal.

Although the embodiment of the present invention has been described above, the above embodiment merely indicates a part of the application example of the present invention, and the technical scope of the present invention is not intended to be limited to the specific configuration of the above embodiment.

REFERENCE SIGNS LIST

100rotating electric machine110case112case body113cylindrical portion121refrigerant passage (flow path)122A first outflow hole122B second outflow hole130stator132stator core132aend surface of stator core133slot137intra-slot conductor138stator coil139coil end (extra-slot conductor)139A welded coil end139B bent coil end140segment conductor150rotor152rotor core153refrigerant passageCa rotation center axisDa upper coil bending direction of welded coil endDb upper coil bending direction of bent coil endHL horizontal lineL1first layerL2second layerL3third layerL4fourth layerTM transmissionVL vertical lineθa first arrangement angleθb second arrangement angleΔθ angle difference