阅读说明：本技术 电动驱动装置 (Electric drive device ) 是由 谷江亮 远藤寛士 于 2020-03-10 设计创作，主要内容包括：一种电动驱动装置,包括旋转电机和变速器。变速器在旋转电机的一个轴向侧上与旋转电机一体地设置。旋转电机包括组装到定子芯部的定子线圈,以具有分别从定子芯部的第一轴向端面和第二轴向端面突出的第一线圈端部分和第二线圈端部分。第二线圈端部分从定子芯部的第二轴向端面突出的轴向突出高度大于第一线圈端部分从定子芯部的第一轴向端面突出的轴向突出高度。第一线圈端部分位于定子芯部的与变速器相同的轴向侧,而第二线圈端部分位于定子芯部的与变速器相反的轴向侧。(An electric drive device includes a rotating electric machine and a transmission. The transmission is provided integrally with the rotary electric machine on one axial side of the rotary electric machine. The rotating electrical machine includes a stator coil assembled to a stator core to have a first coil end portion and a second coil end portion protruding from a first axial end face and a second axial end face of the stator core, respectively. The second coil end portion protrudes from the second axial end surface of the stator core by an axial protruding height that is greater than an axial protruding height of the first coil end portion from the first axial end surface of the stator core. The first coil end portion is located on the same axial side of the stator core as the transmission, and the second coil end portion is located on an opposite axial side of the stator core as the transmission.)

1. An electric drive device (1), characterized by comprising:

a rotary electric machine (10) having a rotor (12) provided on a rotating shaft (11) so as to rotate together with the rotating shaft, a stator (13) having an annular stator core (31) and a multi-phase stator coil (32), and a housing (14) in which the rotor and the stator are housed; and

a transmission (60) having a power transmission unit (61), the power transmission unit (61) being configured to rotate with rotation of the rotating shaft,

wherein the content of the first and second substances,

the transmission is provided integrally with the rotating electrical machine on one side of the rotating electrical machine in an axial direction of the rotating shaft,

the stator coil is assembled to the stator core so as to have a first coil end portion (33A) and a second coil end portion (33B) that protrude from a first axial end face and a second axial end face of the stator core, respectively,

an axial projection height (H2) of the second coil end portion from the second axial end face of the stator core is larger than an axial projection height (H1) of the first coil end portion from the first axial end face of the stator core,

the first coil end portion is located on a same axial side of the stator core as the transmission, and the second coil end portion is located on an opposite axial side of the stator core from the transmission.

2. The electric drive of claim 1,

the stator coil includes a plurality of phase windings (U, V, W),

each phase winding has: a plurality of bent portions (42) formed by bending; and a plurality of joints (46) at each of which a section (40) of the phase winding is joined together by welding,

the turn portion is included in the first coil end portion of the stator coil, and the joint is included in the second coil end portion of the stator coil.

3. The electric drive of claim 2,

for each phase winding of the stator coil, sections of the phase winding are respectively formed by electrical conductor sections (40),

each electrical conductor segment is generally U-shaped to have: a pair of straight portions (41) extending in parallel with each other; and one turn portion (42) of the phase winding extending on the same axial side of the stator core as the transmission to connect the pair of straight portions,

each respective pair of distal ends of the electrical conductor segments are joined together at a joint (46) on an axial side of the stator core opposite the transmission.

4. Electric drive device according to one of claims 1 to 3,

a neutral joint (51) is provided on the same axial side of the stator core as the second coil end portion, at which neutral joints ends of phase windings of the stator coils are joined together to define a neutral point of the stator coil.

5. The electric drive apparatus according to any one of claims 1 to 4,

bus bars (52) through each of which electric power is input to and output from one of the phase windings of the stator coil are provided on the same axial side of the stator core as the second coil end portion,

the housing of the rotary electric machine has a cover portion (16) arranged to cover the second coil end portion,

through holes (53) are formed in the cover portion of the housing, through which each of the bus bars or terminal members connected to the bus bars extends from the inside of the housing to the outside.

6. The electric drive apparatus according to any one of claims 1 to 5,

a heat transfer member (111) is provided in the housing of the rotating electrical machine, the heat transfer member being in contact with the second coil end portion of the stator coil to cause heat to escape from the second coil end portion via the heat transfer member.

7. The electric drive apparatus according to any one of claims 1 to 6,

the housing has a tubular portion (15) for assembling the stator core,

an annular coolant passage (24) through which coolant flows is formed in the tubular portion of the housing.

8. Electric drive device according to one of claims 1 to 7,

on the same axial side of the stator core as the second coil end portion, there are provided: at least one rotational state detection unit (25) configured to detect a rotational state of the rotor; a temperature monitoring unit (115) configured to detect a temperature of the stator coil; and a control device (116) configured to control operation of the rotating electrical machine.

Technical Field

The present disclosure relates to an electric drive device including a rotating electric machine and a transmission.

Background

For example, from japanese patent application publication No. JP 2013-174300A, an electric drive device for a vehicle is known. The electric drive device integrally has a rotating electric machine and a transmission. For such an electric drive apparatus, it is desired to improve output performance and to minimize the size to improve mountability thereof on a vehicle.

On the other hand, in the above-described known electric drive device, the transmission is arranged on one axial side of the rotary electric machine, and the temperature of the rotary electric machine may excessively rise at the transmission-side end portion thereof. This problem becomes particularly significant when the output performance of the electric drive device is improved by increasing the output density of the rotary electric machine, for example, by increasing the current supplied to the stator coils of the rotary electric machine, so that the amount of heat generated in the rotary electric machine is greatly increased.

However, no effective measures are taken in the above-described known electric drive device to dissipate heat generated in the rotating electric machine. Therefore, as the temperature of the rotating electric machine increases, the output performance of the above-described known electric drive device may decrease.

In order to suppress the temperature rise of the rotating electrical machine, it may be considered to limit the output density of the rotating electrical machine. However, in this case, the output performance of the electric drive device will be degraded.

Alternatively, it is conceivable to add a cooling portion or a heat dissipation structure to the rotary electric machine and/or the transmission. However, in this case, the size and/or the number of parts of the electric drive device will be increased.

Disclosure of Invention

According to the present disclosure, an electric drive device is provided that includes a rotating electric machine and a transmission. The rotating electric machine includes a rotor, a stator, and a housing. The rotor is provided on the rotating shaft to rotate together with the rotating shaft. The stator includes an annular stator core and a multi-phase stator coil. The housing accommodates a rotor and a stator. The transmission includes a power transmission unit configured to rotate with rotation of a rotating shaft. Further, in the electric drive device, the transmission is provided integrally with the rotary electric machine on one side of the rotary electric machine in the axial direction of the rotary shaft. It should be noted that the expression "the transmission is provided integrally with the rotary electric machine" used hereinafter means that at least one part (e.g., a housing) of the transmission and at least one part (e.g., a housing) of the rotary electric machine (1) are first formed separately from each other and then joined together as a single piece, or (2) are integrally molded as a single part. The stator coil is assembled to the stator core to have a first coil end portion and a second coil end portion that protrude from a first axial end face and a second axial end face of the stator core, respectively. The second coil end portion protrudes from the second axial end surface of the stator core by an axial protruding height that is greater than an axial protruding height of the first coil end portion from the first axial end surface of the stator core. The first coil end portion is located on the same axial side of the stator core as the transmission, and the second coil end portion is located on an opposite axial side of the stator core as the transmission.

With the above-described structure, since the axial projecting height of the second coil end portion is larger than the axial projecting height of the first coil end portion, the surface area of the second coil end portion is correspondingly larger than the surface area of the first coil end portion. Therefore, the second coil end portion can release more heat than the first coil end portion. Further, the heat generated in the second coil end portion is larger than the heat generated in the first coil end portion. On the other hand, heat is more easily dissipated from the rotating electric machine to the outside on the axial side of the stator core opposite to the transmission than on the same axial side of the stator core as the transmission. Therefore, locating the second coil end portion on the axial side of the stator core opposite the transmission can more effectively promote dissipation of heat generated in the rotary electric machine, as compared with the case where the first coil end portion is located on the axial side of the stator core opposite the transmission.

Further, with the above structure, the axial length of the rotary electric machine is maintained unchanged as compared with the case where the first coil end portion is located on the opposite axial side of the stator core from the transmission. Therefore, the size of the rotating electric machine can be suppressed from increasing, and the size of the entire electric drive device can be suppressed from increasing.

Therefore, with the above configuration, the heat generated in the rotating electric machine can be appropriately dissipated while suppressing an increase in size of the electric drive device.

In another embodiment, the stator coil may include a plurality of phase windings. Each phase winding may have: a plurality of bent portions formed by bending; and a plurality of joints at each of which sections of the phase windings are joined together by welding. The turn portion may be included in a first coil end portion of the stator coil, and the joint may be included in a second coil end portion of the stator coil.

With the above structure, in the second coil end portion, it is necessary to overlap and join each corresponding pair of distal end portions of the sections of the phase winding. Therefore, the axial projection height of the second coil end portion becomes larger than the axial projection height of the first coil end portion. In particular, in the case where each respective pair of distal end portions of the segments of the phase winding are joined by welding to suppress the influence of heat applied during the welding process, it is necessary to ensure a sufficiently long distance from the stator core to the distal end portions, and also to ensure a sufficient welding area at the distal end portions. Therefore, the axial projecting height of the second coil end portion becomes much larger than the axial projecting height of the first coil end portion. As a result, the dissipation of heat generated in the rotating electric machine can be further promoted.

Furthermore, for each phase winding of the stator coil, sections of the phase winding can be formed by sections of an electrical conductor. Each electrical conductor segment is generally U-shaped to have: a pair of linear portions extending in parallel with each other; and one turn of the phase winding extending on the same axial side of the stator core as the transmission to connect the pair of straight portions. Each respective pair of distal ends of the electrical conductor segments may be joined together at a joint located on an opposite axial side of the stator core from the transmission.

With the above configuration, it is possible to easily and reliably achieve that the axial projection height of the second coil end portion from the second axial end surface of the stator core is greater than the axial projection height of the first coil end portion from the first axial end surface of the stator core. Therefore, the dissipation of heat generated in the rotating electrical machine can be facilitated easily and reliably.

In addition, by forming each phase coil of the stator coil by the electric conductor section, the space factor of the stator coil in the stator can be increased, so that the amount of heat generated in the rotating electric machine can be increased by improving the output density of the rotating electric machine. However, even in this case, the heat generated in the rotary electric machine can be appropriately dissipated by promoting dissipation of the heat at the second coil end portion.

In the electric drive device, a neutral joint may be provided on the same axial side of the stator core as the second coil end portion, at which neutral joints ends of phase windings of the stator coil are joined together to define a neutral point of the stator coil.

Since the neutral joint is located away from the stator core, heat may not easily escape from the neutral joint, and thus the temperature tends to rise at the neutral joint. However, by positioning the neutral joint on the same axial side of the stator core as the second coil end portion, i.e., the axial side of the stator core opposite the transmission, heat dissipation from the neutral joint can be promoted.

In the electric drive device, a bus bar through which electric power is input to and output from one of the phase windings of the stator coil may be provided on the same axial side of the stator core as the second coil end portion. The housing of the rotary electric machine may have a cover portion arranged to cover the second coil end portion. Through holes through which each of the bus bars or the terminal members connected to the bus bars extends from the inside of the housing to the outside are formed in the cover portion of the housing.

With the above structure, heat is easily released from the bus bar. Therefore, heat can escape from the second coil end portion to the outside of the case via the bus bar. As a result, dissipation of heat generated in the rotating electric machine can be promoted.

A heat transfer member may be provided in the housing of the rotary electric machine, the heat transfer member being in contact with the second coil end portion of the stator coil to dissipate heat from the second coil end portion via the heat transfer member.

Therefore, the heat transfer member can further promote dissipation of heat generated in the rotating electric machine.

The housing may have a tubular portion to which the stator core is assembled. An annular coolant passage through which coolant flows may be formed in the tubular portion of the housing.

With the above configuration, heat transferred from the transmission to the tubular portion of the case can be dissipated by heat exchange with the coolant flowing through the coolant passage. Further, the transfer of heat from the transmission to the axial side of the stator core opposite the transmission is hindered by the coolant passage. Therefore, heat dissipation from the axial side of the stator core opposite to the transmission can be further promoted.

In the electric drive device, it is possible to provide on the same axial side of the stator core as the second coil end portion: at least one rotational state detection unit configured to detect a rotational state of the rotor; a temperature monitoring unit configured to detect a temperature of the stator coil; and a control device configured to control operation of the rotating electrical machine.

In the case where the rotation state detection unit, the temperature monitoring unit, and/or the control device are provided in the electric drive device, the performance of these devices may be affected by the heat generated in the rotating electric machine. In view of this, as described above, heat is more easily dissipated on the same axial side of the stator core as the second coil end portion (i.e., the axial side of the stator core opposite the transmission) than on the same axial side of the stator core as the first coil end portion (i.e., the same axial side of the stator core as the transmission). Therefore, positioning these devices on the same axial side of the stator core as the second coil end portions can maintain the performance of these devices, thereby improving the reliability of the rotary electric machine.

Drawings

Fig. 1 is a longitudinal sectional view of an electric drive device having a rotary electric machine and a transmission integrated therein according to an exemplary embodiment.

Fig. 2 is a schematic diagram showing a manner of assembling electric conductor segments forming a stator coil, which together with a stator core constitutes a stator of a rotary electric machine, to a stator core.

Fig. 3 is an expanded view of a part of the stator in the circumferential direction.

Fig. 4 is a schematic diagram showing the structure of a transmission according to an exemplary embodiment.

Fig. 5 is a schematic diagram showing a structure of a transmission according to a modification.

Fig. 6 is a schematic diagram showing a structure of a transmission according to another modification.

Fig. 7 is a schematic diagram showing a structure of a transmission according to still another modification.

Fig. 8 is a longitudinal sectional view of an electric drive device according to a modification.

Fig. 9 is a longitudinal sectional view of an electric drive device according to another modification.

Fig. 10 is a longitudinal sectional view of an electric drive device according to still another modification.

Detailed Description

Hereinafter, exemplary embodiments are described with reference to the accompanying drawings.

Fig. 1 shows the overall structure of an electric drive device 1 according to an exemplary embodiment.

In the present embodiment, the electric drive apparatus 1 is designed for a vehicle. It should be noted that the electric drive 1 may also be used in other applications, such as industrial, marine, aeronautical and domestic applications.

As shown in fig. 1, the electric drive device 1 according to the present embodiment includes a rotary electric machine 10 and a transmission 60 that are integrally formed with each other.

In the present embodiment, the rotary electric machine 10 is configured as an inner-rotor type multi-phase AC motor. In addition, the rotary electric machine 10 may be a synchronous motor or an induction motor.

Hereinafter, a direction in which the central axis of the rotating shaft 11 of the rotary electric machine 10 extends will be referred to as an axial direction, a direction extending radially from the central axis of the rotating shaft 11 will be referred to as a radial direction, and a direction extending along a circle centered on the central axis of the rotating shaft 11 will be referred to as a circumferential direction.

The rotating electric machine 10 includes: a rotating shaft 11; a rotor 12, the rotor 12 being provided on the rotation shaft 11 to rotate together with the rotation shaft 11; a stator 13, the stator 13 being positioned radially outside the rotor 12 so as to surround the rotor 12; and a housing 14 in which the rotor 12 and the stator 13 are housed in the housing 14.

The rotor 12 and the stator 13 are coaxially arranged to radially face each other. The housing 14 is provided to surround the rotor 12 and the stator 13 from both radially outer and axial sides thereof.

Specifically, the housing 14 has a tubular portion 15 and a lid portion 16. The tubular portion 15 has a bottomed tubular shape. The tubular portion 15 forms an end wall 17 at one axial end thereof, and the other axial end thereof is open. The tubular portion 15 is arranged to surround the rotor 12 and the stator 13 from the radially outer side thereof, and the end wall 17 covers the rotor 12 and the stator 13 from one axial side thereof. The cover portion 16 is fixed to the open axial end portion of the tubular portion 15 by a fixing mechanism (not shown) such as a bolt to cover the rotor 12 and the stator 13 from the other axial side thereof. The end wall 17 of the tubular portion 15 is located on the same axial side of the rotor 12 and the stator 13 as the transmission 60, and the cover portion 16 is located on the opposite axial side of the rotor 12 and the stator 13 from the transmission 60.

The bearing 21 is fixed to the lid portion 16 of the housing 14. On the other hand, the bearing 22 is fixed to the end wall 17 of the tubular portion 15 of the housing 14. The rotation shaft 11 is provided to extend through a through hole formed in a central portion of the lid portion 16 and a through hole formed in a central portion of the end wall 17. The rotary shaft 11 and the rotor 12 are both supported by the housing 14 via bearings 21, 22 so as to be rotatable together.

The rotor 12 includes: a rotor core portion formed by laminating a plurality of magnetic steel sheets in an axial direction and fixed to the rotating shaft 11; and a plurality of permanent magnets held in the rotor core.

The stator 13 is located radially outward of the rotor 12 to radially face the rotor 12 with a predetermined air gap formed therebetween. The stator 13 includes an annular stator core 31 and a multiphase stator coil 32. The stator core 31 is formed by laminating a plurality of annular magnetic steel sheets in the axial direction and fixing them together by, for example, caulking. The stator coil 32 is, for example, a three-phase coil including a U-phase winding, a V-phase winding, and a W-phase winding. The U-phase, V-phase, and W-phase windings are star-connected (i.e., Y-connected) to define a neutral point therebetween. The stator coil 32 is assembled to the stator core 31 to have annular first and second coil ends 33A and 33B, the first and second coil ends 33A and 33B protruding from opposite pairs of first and second axial end surfaces of the stator core 31, respectively.

The stator 13 is fixed to the housing 14 by fixing the stator core 31 to the radially inner side of the tubular portion 15 of the housing 14. In addition, the stator core 31 may be interference-fitted to the radially inner periphery of the tubular portion 15 of the housing 14 by, for example, shrink fitting or press fitting.

An annular coolant passage 24 through which coolant flows is formed in the tubular portion 15 of the housing 14. Specifically, the coolant passage 24 is formed to flow the coolant between an inlet and an outlet, not shown, in the circumferential direction. Further, the coolant passage 24 is positioned to radially overlap the stator core 31 in the axial direction.

In addition, in the present embodiment, the coolant is implemented by cooling water. It should be noted that the coolant may alternatively be realized by, for example, lubricating oil.

A rotation angle sensor 25 is provided in the rotary electric machine 10, and the above-described rotation angle sensor 25 functions as a rotation state detection unit to detect the rotation state of the rotor 12. The rotation angle sensor 25 is of an electromagnetic induction type and is constituted by a resolver, for example. The resolver comprises: a resolver rotor fixed to the rotating shaft 11; and a resolver stator arranged radially outside the resolver rotor to radially face the resolver rotor. More specifically, the resolver rotor is formed of stacked flat plates. The resolver rotor is arranged coaxially with a rotating shaft 11 extending through the resolver rotor in an axial direction. The resolver stator, on the other hand, is fixed to the cover portion 16 of the housing 14. The resolver stator includes a stator core and a stator coil, both not shown.

In the rotary electric machine 10 configured as described above, energization of the stator coil 32 is controlled by an inverter and a controller, both of which are not shown in the drawing. Therefore, by controlling the energization of the stator coil 32, the torque acting on the rotating shaft 11 during the operation of the rotating electrical machine 10 in the torque generation mode or the power generation mode can be controlled.

In the present embodiment, the stator coil 32 is formed by: first, a plurality of substantially U-shaped electrical conductor segments 40 shown in fig. 2 are assembled to the stator core 31, and then each corresponding pair of distal ends of the electrical conductor segments 40 is joined by welding.

Fig. 2 shows the manner in which the electrical conductor segments 40 are assembled to the stator core 31. Fig. 3 shows the electrical conductor segments 40 assembled to the stator core 31. It should be noted that, for the sake of simplicity, only the electric conductor sections of the electric conductor sections 40 that are joined to each other to form one of the U-phase, V-phase, and W-phase windings of the stator coil 32 are shown in fig. 3.

As shown in fig. 2, the stator core 31 includes an annular back core 35 and a plurality of teeth 36, each tooth 36 protruding radially inward from the back core 35 and being spaced apart circumferentially at a predetermined pitch. The stator core 31 also has a plurality of slots 37, each slot 37 being formed between one circumferentially adjacent pair of the teeth 36.

The groove 37 includes a U-phase groove group, a V-phase groove group, and a W-phase groove group, each including a predetermined number of grooves 37, which are repeatedly arranged in this order in the circumferential direction. More specifically, in the present embodiment, the groove 37 includes pairs of U-phase grooves 37A and 37B, V- phase grooves 37A and 37B and W- phase grooves 37A and 37B that are repeatedly arranged in this order in the circumferential direction.

For each slot 37, the depth direction of the slot 37 coincides with the radial direction of the stator core 31. Further, each slot 37 is partially open on the radially inner surface of the stator core 31. In addition, each slot 37 is formed to have a predetermined number of electrical conductor segments 40, the above-mentioned electrical conductor segments 40 being arranged in the slot 37 in alignment with each other in the depth direction of the slot 37 (i.e., the radial direction of the stator core 31).

As shown in fig. 2, each electrical conductor segment 40 is generally U-shaped to have: a pair of linear portions 41, the pair of linear portions 41 extending in parallel with each other; and a bent portion 42 formed by bending the bent portion 42 so as to connect the end portions of the linear portions 41 on the same side. The length of the linear portion 41 is longer than the axial thickness of the annular stator core 31. The turn portion 42 also has a pair of inclined portions 43 formed on opposite sides of the center of the turn portion 42, respectively, such that the above-described inclined portions 43 extend obliquely at a predetermined angle with respect to a first axial end surface (i.e., an upper end surface in fig. 2 and 3) of the stator core 31.

In the present embodiment, the electrical conductor segment 40 is obtained by cutting and plastically deforming an electrical wire including an electrical conductor and an insulating coating. The electrical conductor is formed of an electrically conductive metal (e.g., copper) and has a generally rectangular cross-section. The insulating coating is formed of an electrically insulating resin and is provided to cover an outer surface of the electrical conductor.

The electrical conductor segments 40 are arranged in a predetermined number of radially aligned layers in each slot 37 of the stator core 31. One straight portion 41 of each electrical conductor segment 40 is arranged at the nth layer from the radially inner side in one slot 37, and the other straight portion 41 is arranged at the (n +1) th layer from the radially inner side of the other slot 37, where n is a natural number greater than or equal to 1.

More specifically, in the present embodiment, as described above, the slots 37 of the stator core 31 include a plurality of slot pairs, each of which includes the first slot 37A and the second slot 37B, the first slot 37A and the second slot 37B being adjacent to each other in the circumferential direction and belonging to the same phase (i.e., the same one of the U-phase, the V-phase, and the W-phase). On the other hand, the electrical conductor segments 40 forming the stator coil 32 include a plurality of pairs of electrical conductor segments, each pair of electrical conductor segments including a first electrical conductor segment 40A and a second electrical conductor segment 40B, the first electrical conductor segment 40A and the second electrical conductor segment 40B having the same shape and size.

For each pair of electrical conductor segments, the straight portions 41 of the first electrical conductor segment 40A are inserted into the first slot 37A of the first slot pair and the first slot 37A of the second slot pair, respectively, from a first axial side (i.e., an upper side in fig. 2 and 3) of the stator core 31, and the straight portions 41 of the second electrical conductor segment 40B are inserted into the second slot 37B of the first slot pair and the second slot 37B of the second slot pair, respectively, from the first axial side of the stator core 31. That is, the first and second electrical conductor segments 40A and 40B are circumferentially offset from each other by a slot pitch. Further, the first slot pair and the second slot pair are positioned one pole pitch (or six slot pitches in this embodiment) away from each other. In addition, one insulation sheet 38 is provided in each slot 37 of the stator core 31 to electrically insulate between the stator core 31 and the stator coil 32 (i.e., the electrical conductor segments 40).

After the linear portions 41 of the electrical conductor segments 40 are inserted into the corresponding slots 37 of the stator core 31, the protruding portions of the linear portions 41 of the electrical conductor segments 40 that protrude outside the corresponding slots 37 on the second axial side (i.e., the lower side in fig. 2 and 3) of the stator core 31 are twisted toward opposite sides, respectively, in the circumferential direction for each electrical conductor segment 40, so that the protruding portions extend obliquely at a predetermined angle with respect to the second axial end face (i.e., the lower end face in fig. 2 and 3) of the stator core 31. Thus, each protruding portion of the straight portion 41 is converted into an inclined portion 45 of the electrical conductor segment 40, the inclined portion 45 extending substantially half the pole pitch in the circumferential direction of the stator core 31.

Then, as shown in fig. 3, on the second axial side of the stator core 31, each corresponding pair of distal end portions 47 of the electrical conductor segments 40 (i.e., the end portions 47 of the electrical conductor segments 40 on the opposite side from the turn portions 42) are joined (e.g., by welding) to form a joint (or weld) 46 therebetween. Thus, all of the electrical conductor segments 40 are electrically connected in a predetermined pattern to form the stator coil 32.

More specifically, the distal ends 47 of the electrical conductor segments 40 are exposed from the respective insulative coatings, thereby forming exposed portions 47 of the electrical conductor segments 40. Each tab 46 is formed between a corresponding pair of exposed portions 47 of the electrical conductor segments 40.

As shown in fig. 3, the stator coil 32 assembled to the stator core 31 in the above-described manner has a first coil end portion 33A on a first axial side (i.e., an upper side in fig. 3) of the stator core 31 and a second coil end portion 33B on a second axial side (i.e., a lower side in fig. 3) of the stator core 31. The first coil end portion 33A includes a turn 42 of the electrical conductor segment 40 protruding from a first axial end face (i.e., an upper end face in fig. 3) of the stator core 31. The second coil end portion 33B includes: an inclined portion 45 of the electrical conductor segment 40 protruding from the second axial end face (i.e., the lower end face in fig. 3) of the stator core 31; and a joint 46 formed between exposed portions 47 of the electrical conductor segments 40. As shown in fig. 3, the joint 46 is formed to extend substantially parallel to the axial direction.

With the above-described structure of the stator coil 32 according to the present embodiment, the axial protrusion heights of the first and second coil end portions 33A and 33B, which protrude from the first and second axial end surfaces of the stator core 31, respectively, are different from each other.

More specifically, in the present embodiment, the following dimensional relationship is satisfied: h1 < H2, where H1 is the axial projection height of the first coil end portion 33A from the first axial end face of the stator core 31, and H2 is the axial projection height of the second coil end portion 33B from the second axial end face of the stator core 31.

As described above, in the present embodiment, the first coil end portion 33A includes the turn portion 42 of the electrical conductor section 40, while the second coil end portion 33B includes the inclined portion 45 of the electrical conductor section 40 and the joint 46 formed between the distal end portion 47 (i.e., the exposed portion 47) of the electrical conductor section 40. In the second coil end portion 33B, it is necessary to overlap and engage each corresponding pair of distal end portions 47 of the electrical conductor section 40. Therefore, the axial projection height H2 of the second coil end portion 33B becomes larger than the axial projection height H1 of the first coil end portion 33A.

In particular, in the case where each of the respective paired distal end portions 47 of the electrical conductor segments 40 is joined by welding, it is necessary to ensure a sufficiently long distance from the stator core 31 to the distal end portions 47 during the welding, and also to ensure a sufficient welding area at the distal end portions 47 of the electrical conductor segments 40. Therefore, the axial projection height H2 of the second coil end portion 33B becomes much larger than the axial projection height H1 of the first coil end portion 33A.

In addition, the left-right direction in fig. 1 coincides with the axial direction, and in fig. 1, the first coil end portion 33A and the second coil end portion 33B represent a left coil end portion and a right coil end portion of the stator coil 32, respectively.

In the present embodiment, a neutral joint 51 is provided on the same axial side of the stator core 31 as the second coil end portion 33B (i.e., on the right side of the stator core 31 in fig. 1), at which neutral joint 51 the ends of the U-phase, V-phase, and W-phase windings of the stator coil 32 are joined together to define a neutral point of the stator coil 32. More specifically, as shown in fig. 1, at the neutral joint 51, the ends of the U-phase winding, the V-phase winding, and the W-phase winding of the stator coil 32 are superposed in the axial direction and joined together by, for example, welding.

Further, in the present embodiment, a bus bar 52 is provided on the same axial side of the stator core 31 as the second coil end portion 33B, and electric power is input to and output from the U-phase winding, the V-phase winding, and the W-phase winding of the stator coil 32 through this bus bar 52. Each bus bar 52 is provided for a corresponding one of the phase windings of the stator coils 32. More specifically, each bus bar 52 is connected to an end of the corresponding phase winding on the opposite side from the neutral point. In addition, all the bus bars 52 may be integrated as a bus bar module, for example, by resin molding.

A through hole 53 is formed in the lid portion 16 of the housing 14, and a part of the bus bar 52 protrudes to the outside of the housing 14 through the through hole 53. A power harness 54 is connected to the protruding portion of the bus bar 52, the power harness 54 being provided for inputting and outputting electric power to and from the stator coil 32, respectively. In addition, a sealant is filled in the through hole 53 to seal a gap between the bus bar 52 and an inner wall surface of the through hole 53.

In addition, as an alternative, the bus bar 52 may be configured to extend within the housing 14 and be connected with a terminal member, which may extend from the inside of the housing 14 to the outside through a through hole 53 formed in the lid portion 16 of the housing 14.

The electric drive device 1 according to the present embodiment is configured to be used as a power source in a vehicle to generate power (or torque) for rotating left and right wheels of the vehicle.

Specifically, the power generated by the rotating electrical machine 10 is transmitted to the wheels of the vehicle via the transmission 60, thereby causing the vehicle to travel. In particular, in the present embodiment, a differential 62 is provided in the transmission 60 to distribute power between the left and right wheels of the vehicle.

As shown in fig. 1, the transmission 60 includes: a power transmission unit 61, the power transmission unit 61 being configured to transmit power generated by the rotating electric machine 10; the differential 62 described above; and a case 63, wherein the power transmission unit 61 and the differential 62 are housed in the case 63. Lubricating oil is provided in the housing 63 for lubricating the power transmission unit 61 and the differential 62.

The housing 63 is provided at one axial end thereof with a flat end wall 63 a. The end wall 63a of the housing 63 of the transmission 60 and the end wall 17 of the housing 14 of the rotary electric machine 10 are arranged to abut each other and joined together by an engaging member such as a bolt. That is, the housing 63 of the transmission 60 is provided integrally with the housing 14 of the rotary electric machine 10 in one piece on one axial side (i.e., the left side in fig. 1) of the rotary electric machine 10. Therefore, the rotary electric machine 10 and the transmission 60 are integrated into a single structure (or mechanically joined together into a single body).

The transmission 60 has a rotation input portion 64, and the rotation input portion 64 is provided integrally with the rotating shaft 11 of the rotating electrical machine 10 so as to rotate together with the rotating shaft 11. The rotation of the rotating shaft 11 is input to the transmission 60 via the rotation input portion 64, and then the rotation is output from the paired output shafts 65A, 65B of the transmission 60 via the power transmission unit 61 and the differential 62. More specifically, the rotation input via the rotation input portion 64 is increased or decreased in the transmission, and then output from the output shafts 65A, 65B. By the rotation of the output shafts 65A, 65B, the left and right wheels of the vehicle are also rotated.

It should be noted that fig. 1 schematically shows only the structure of the electric drive device 1, in which: the rotary electric machine 10 and the transmission 60 are coaxially arranged, and one of the paired output shafts 65A, 65B of the transmission 60, i.e., the output shaft 65A, is configured to extend through the hollow portion 11a of the rotary shaft 11.

Although not shown in detail in fig. 1, the rotating shaft 11 is inserted into a through hole formed in the end wall 17 of the housing 14 of the rotary electric machine 10 and a through hole formed in the end wall 63a of the housing 63 of the transmission 60. Further, a seal member (e.g., a sliding seal) is provided between the outer peripheral surface of the rotating shaft 11 and the inner wall surface of the through hole formed in the end wall 17, 63a of the housing 14, 63. In addition, an oil drain hole may be formed in the case 63 of the transmission 60, through which the amount of lubricating oil provided in the case 63 may be adjusted.

Next, the structure of the transmission 60 according to the present embodiment will be described in detail with reference to fig. 4.

In the present embodiment, the power transmission unit 61 of the transmission 60 is implemented by a double-pinion planetary gear mechanism 70. The planetary gear mechanism 70 includes: a ring gear 71 formed with internal teeth; a sun gear 72 formed with external teeth; a pair of pinions 73, 74 arranged coaxially with each other; and a carrier 75 rotatably supporting the pair of pinions 73, 74. The ring gear 71 is fixed to the housing 63 of the transmission 60. The sun gear 72 may be provided integrally with the rotary shaft 11 as the rotation input portion 64 of the transmission 60 to rotate together with the rotary shaft 11. Of the paired pinions 73, 74, the pinion 73 is arranged to mesh with the ring gear 71, and the pinion 74 is arranged to mesh with the sun gear 72. The carrier 75 is fixed to a housing 81 of the differential 62.

It should be noted that the planetary gear mechanism 70 may alternatively include a plurality of paired pinion gears 73, 74. Further, it should also be noted that the rotational input 64 may alternatively include splines, and the sun gear 72 may be fixed to the splines.

The differential 62 includes: the above-mentioned housing 81; a plurality of pinions 82 provided in the housing 81; and a pair of side gears 83 provided in the housing 81 and engaged to the output shafts 65A, 65B by spline fitting, press fitting, or the like, respectively.

Further, in the transmission 60, the rotary shaft 11 is rotatably supported by a bearing 85. The carrier 75 of the planetary gear mechanism 70 is rotatably supported by a bearing 86. The housing 81 of the differential 62 is rotatably supported by bearings 87.

In the transmission 60 configured as described above, during rotation of the rotary shaft 11 (i.e., during rotation of the rotor 12), the pinion gears 73, 74 rotate with rotation of the sun gear 72. Further, the carrier 75 rotates together with the housing 81 of the differential 62 with the rotation of the pinion gears 73, 74. That is, the rotation of the rotating shaft 11 is transmitted to the case 81 of the differential 62 by being reduced in speed at a given reduction ratio by the planetary gear mechanism 70. Further, the rotation of the case 81 of the differential 62 is further transmitted to the output shafts 65A, 65B by the engagement between the pinion 82 and the side gear 83. When the output shafts 65A, 65B rotate at different speeds during cornering of the vehicle, power is appropriately distributed by the differential 62 between the output shafts 65A, 65B, and thus between the left and right wheels of the vehicle.

In the electric drive device 1 according to the present embodiment, the transmission 60 is provided integrally with the rotary electric machine 10 in a single structure on one axial side (i.e., the left side in fig. 1) of the rotary electric machine 10. Therefore, the heat generated in the rotary electric machine 10 is less likely to escape at the axial side where the transmission 60 is provided than at the axial side opposite to the transmission 60. In view of this, in the present embodiment, the following measures are taken to promote the dissipation of heat generated in the rotary electric machine 10.

As described above, in the stator 13 of the rotary electric machine 10, the axial protrusion height H1 and the axial protrusion height H2 at which the first coil end portion 33A and the second coil end portion 33B of the stator coil 32 protrude from the first axial end face and the second axial end face of the stator core 31, respectively, are different from each other. More specifically, the axial projection height H2 at which the second coil end portion 33B projects from the second axial end face of the stator core 31 is greater than the axial projection height H1 at which the first coil end portion 33A projects from the first axial end face of the stator core 31 (see fig. 3). Therefore, in the present embodiment, the rotary electric machine 10 is assembled to the transmission 60 such that the first coil end portion 33A is located on the same axial side of the stator core 31 as the transmission 60 (i.e., the left side of the stator core 31 in fig. 1), and the second coil end portion 33B is located on the opposite axial side of the stator core 31 from the transmission 60 (i.e., the right side of the stator core 31 in fig. 1). Therefore, heat generated in the rotary electric machine 10 can be dissipated more efficiently than in the case where the first coil end portion 33A is located on the opposite axial side of the stator core 31 from the transmission 60.

More specifically, the surface area of the second coil end portion 33B is larger than the surface area of the first coil end portion 33A, and therefore, the second coil end portion 33B can release more heat than the first coil end portion 33A. Further, the amount of heat generated in the second coil end portion 33B is larger than the amount of heat generated in the first coil end portion 33A. On the other hand, heat is more likely to escape from the rotary electric machine 10 to the outside on the opposite axial side of the stator core 31 from the transmission 60 than on the same axial side of the stator core 31 as the transmission 60. Therefore, the positioning of the second coil end portion 33B on the opposite axial side of the stator core 31 from the transmission 60 can promote the dissipation of heat generated in the rotary electric machine 10, as compared with the case where the first coil end portion 33A is positioned on the opposite axial side of the stator core 31 from the transmission 60.

In particular, the second coil end portion 33B includes joints 46, and at each joint 46, a corresponding pair of distal end portions 47 (i.e., exposed portions 47) of the electrical conductor section 40 are superposed on and joined to each other. Therefore, the axial projection height H2 at which the second coil end portion 33B projects from the second axial end face of the stator core 31 becomes greater than the axial projection height H1 at which the first coil end portion 33A projects from the first axial end face of the stator core 31. Therefore, with respect to the dissipation of heat generated in the rotary electric machine 10, it is more advantageous to locate the second coil end portion 33B on the opposite axial side of the stator core 31 from the transmission 60 than to locate the first coil end portion 33A on the opposite axial side of the stator core 31 from the transmission 60.

Further, when each of the respective paired distal end portions 47 of the electrical conductor segments 40 is joined by welding, in order to suppress the influence of heat applied during the welding, it is necessary to ensure a sufficiently long distance from the stator core 31 to the distal end portions 47. Therefore, the distance from the stator core 31 to the formed weld (i.e., the joint 46) becomes longer, and the axial projecting height H2 of the second coil end portion 33B increases.

Further, in the present embodiment, on the same axial side of the stator core 31 as the second coil end portion 33B, a neutral connector 51 for defining a neutral point of the stator coil 32 and bus bars 52 connected to the phase windings of the stator coil 32, respectively, are provided. Therefore, the heat generated by the supply of electric power to the stator coil 32 can also be dissipated on the axial side of the stator core 31 opposite to the transmission 60 via the neutral joint 51 and the bus bar 52.

According to the present embodiment, the following advantageous effects can be achieved.

The electric drive device 1 according to the present embodiment includes a rotary shaft 10 and a transmission 60. The rotary electric machine 10 includes a rotor 12, a stator 13, and a housing 14. The rotor 12 is fixed to the rotation shaft 11 to rotate together with the rotation shaft 11. The stator 13 includes an annular stator core 31 and a three-phase stator coil 32. The housing 14 houses the stator 12 and the rotor 13. The transmission 60 includes a power transmission unit 61, and the power transmission unit 61 is configured to rotate with rotation of the rotary shaft 11. Further, in the electric drive device 1, the transmission 60 is provided integrally with the rotary electric machine 10 in a single structure on one axial side (i.e., the left side in fig. 1) of the rotary electric machine 10. The stator coil 32 is assembled to the stator core 31 to have a first coil end portion 33A and a second coil end portion 33B that protrude from a first axial end face and a second axial end face of the stator core 31, respectively. The axial projection height H2 at which the second coil end portion 33B projects from the second axial end face of the stator core 31 is greater than the axial projection height H1 at which the first coil end portion 33A projects from the first axial end face of the stator core 31. The first coil end portion 33A is located on the same axial side of the stator core 31 as the transmission 60, while the second coil end portion 33B is located on the opposite axial side of the stator core 31 from the transmission 60.

With the above configuration, heat generated in the rotary electric machine 10 can be dissipated more efficiently than in the case where the first coil end portion 33A is located on the opposite axial side of the stator core 31 from the transmission 60.

Further, with the above-described structure, the axial length of the rotary electric machine 10 is kept unchanged as compared with the case where the first coil end portion 33A is positioned on the opposite axial side of the stator core 31 from the transmission 60 (i.e., the second coil end portion 33B is positioned on the same axial side of the stator core 31 as the transmission 60). Therefore, the size of the rotating electrical machine 10 can be suppressed from increasing, and the size of the electric drive device 1 as a whole can be suppressed from increasing.

Therefore, with the above configuration, the heat generated in the rotating electric machine 10 can be appropriately dissipated while suppressing an increase in size of the electric drive device 1.

In addition, the thermal rating of the stator coil 32 is designed to be within a range such that the highest temperature in the stator coil 32 does not exceed the heat-resistant temperature of the insulating coating forming the electrical conductor segments 40 of the stator coil 32. Accordingly, the upper limit of the output of the rotating electric machine 10 can be increased by effectively dissipating the heat generated by supplying the electric power to the stator coil 32.

In the present embodiment, the stator coil 32 includes a U-phase winding, a V-phase winding, and a W-phase winding. Each phase winding of the stator coil 32 has: a bent portion 42 formed by bending the bent portion 42; and joints 46 at each of the above joints 46, two sections of the phase winding (more specifically, in the present embodiment, two electrical conductor sections 40 forming the phase winding) are joined together by welding. The turn 42 is included in the first coil end portion 32A and the junction 46 is included in the second coil end portion 32B.

With the above-described structure, in the second coil end portion, it is necessary to overlap and join each corresponding pair of distal end portions 47 of the electrical conductor section 40. Therefore, the axial projection height H2 of the second coil end portion 33B becomes larger than the axial projection height H1 of the first coil end portion 33A. In particular, in the case where each respective pair of distal end portions 47 of the electrical conductor segments 40 is joined by welding to suppress the influence of heat applied during the welding process, it is necessary to ensure a sufficiently long distance from the stator core 31 to the distal end portions 47, and also to ensure a sufficient welding area at the distal end portions 47 of the electrical conductor segments 40. Therefore, the axial projection height H2 of the second coil end portion 33B becomes much larger than the axial projection height H1 of the first coil end portion 33A. As a result, the dissipation of heat generated in the rotating electric machine 10 can be further promoted.

In addition, at the welded portion (i.e., the joint 46) included in the second coil end portion 32B, fatigue may be generated due to repeated application of thermal stress. In addition, the amount of heat generated may increase due to a change in electrical conductivity caused by welding. In view of this, by positioning the second coil end portion 33B on the opposite axial side of the stator core 31 from the transmission 60, it is possible to promote cooling of the welded portion, thereby preventing a rapid temperature rise. Therefore, occurrence of a failure condition (e.g., fatigue) at the welded portion can be suppressed.

In the present embodiment, each of the U-phase winding, the V-phase winding, and the W-phase winding of the stator coil 32 is formed of a plurality of electrical conductor segments 40. In other words, for each phase winding of the stator coil 32, the sections of the phase windings that are joined to one another at the joints 46 are each formed by an electrical conductor section 40. Each electrical conductor segment 40 is generally U-shaped to have: a pair of straight portions 41 extending parallel to each other; and one turn portion 42 of the phase winding extending on the same axial side of the stator core 31 as the transmission to connect the pair of straight portions 41. Each corresponding pair of distal end portions 47 of the electrical conductor segments 40 are joined together at one joint 46 located on the opposite axial side of the stator core 31 from the transmission 60.

With the above structure, it can be easily and reliably achieved that the axial protrusion height H2 of the second coil end portion 33B from the second axial end face of the stator core 31 is greater than the axial protrusion height H1 of the first coil end portion 33A from the first axial end face of the stator core 31. Therefore, the dissipation of heat generated in the rotating electrical machine 10 can be facilitated easily and reliably.

In addition, by forming each phase coil of the stator coil 32 by the electric conductor segments 40, the space factor of the stator coil 32 in the stator 13 can be increased, so that the amount of heat generated in the rotary electric machine 10 can be increased by improving the output density of the rotary electric machine 10. However, even in this case, the heat generated in the rotary electric machine 10 can be appropriately dissipated by promoting the heat dissipation at the second coil end portion 33B.

In the present embodiment, a neutral joint 51 is provided on the same axial side of the stator core 31 as the second coil end portion 33B, at which neutral joint 51 the ends of the phase windings of the stator coil 32 are joined together to define a neutral point of the stator coil 32.

Since the neutral joint 51 is located away from the stator core 31, heat may not easily escape from the neutral joint 51, and thus the temperature easily rises at the neutral joint 51. However, by positioning the neutral joint 51 on the same axial side of the stator core 31 as the second coil end portion 33B, that is, on the opposite axial side of the stator core 31 from the transmission 60, it is possible to promote the dissipation of heat from the neutral joint 51.

In the present embodiment, bus bars 52 are provided on the same axial side of the stator core 31 as the second coil end portion 33B, and electric power is input to and output from one of the phase windings of the stator coil 32 through each of the above-described bus bars 52. The housing 14 of the rotary electric machine 10 has a lid portion 16, and the above-mentioned lid portion 16 is arranged to cover the second coil end portion 33B. Through holes 53 are formed in the cover portion 16 of the housing 14, and each bus bar (alternatively, a terminal member connected to the bus bar 52) extends from the inside of the housing 14 to the outside through the above through hole 53.

With the above structure, heat is easily released from the bus bar 52. Therefore, heat can escape from the second coil end portion 33B to the outside of the case 14 via the bus bar 52. As a result, dissipation of heat generated in the rotating electric machine 10 can be promoted.

In the present embodiment, the housing 14 has a tubular portion 15 to which the stator core 31 is assembled. An annular coolant passage 24 through which coolant flows is formed in the tubular portion 15 of the housing 14.

With the above configuration, heat transferred from the transmission 60 to the tubular portion 15 of the case 14 can be dissipated by heat exchange with the coolant flowing through the coolant passage 24. Further, the transfer of heat from the transmission 60 to the axial side of the stator core 31 opposite to the transmission 60 is hindered by the coolant passage 24. Therefore, heat dissipation from the axial side of the stator core 31 opposite to the transmission 60 can be further promoted.

In the present embodiment, a rotation angle sensor 25 is provided on the same axial side of the stator core 31 as the second coil end portion 33B, and the above-described rotation angle sensor 25 functions as a rotation state detection unit to detect the rotation state of the rotor 12.

As described above, heat is more easily dissipated on the same axial side of the stator core 31 as the second coil end portion 33B (i.e., the axial side of the stator core 31 opposite the transmission 60) than on the same axial side of the stator core 31 as the first coil end portion 33A (i.e., the same axial side of the stator core 31 as the transmission 60). Therefore, by positioning the rotation angle sensor 25 on the same axial side of the stator core 31 as the second coil end portion 33B, the performance of the rotation angle sensor 25 can be maintained, thereby improving the reliability of the rotating electrical machine 10.

While the particular embodiments described above have been shown and described, it will be understood by those skilled in the art that various changes, alterations and modifications may be made without departing from the spirit of the disclosure.

(1) For example, in the above embodiment, the transmission 60 is configured as shown in fig. 4.

Alternatively, the transmission 60 may have the structure shown in fig. 5. In this structure, the rotary electric machine 10 and the transmission 60 are arranged coaxially with each other. The power transmission unit 61 of the transmission 60 is realized by a helical gear mechanism 90. The helical gear mechanism 90 includes a plurality of helical gear pairs having different reduction ratios (the same as fig. 6 and 7 described later). More specifically, the helical gear mechanism 90 includes, for example: a first gear pair 91 configured to rotate with rotation of the rotating shaft 11; and a second gear pair 92 configured to rotate the housing 81 of the differential 62 with rotation of the first gear pair 91. During rotation of the rotary shaft 11 (i.e., during rotation of the rotor 12), the pair of gears 91, 92 also rotate, thereby rotating the pair of output shafts 65A, 65B coaxially with the rotary shaft 11.

As another alternative, the transmission 60 may have the structure shown in fig. 6. In this structure, the rotary electric machine 10 and the transmission 60 are of a multi-shaft type. The power transmission unit 61 of the transmission 60 is realized by the helical gear mechanism 100. The helical gear mechanism 100 includes, for example: a first gear pair 101 configured to rotate with rotation of the rotating shaft 11; and a second gear pair 102 configured to rotate the housing 81 of the differential 62 with rotation of the first gear pair 101. During rotation of the rotary shaft 11 (i.e., during rotation of the rotor 12), the gear pairs 101, 102 also rotate, thereby rotating the paired output shafts 65A, 65B about axes different from the rotary shaft 11.

As a further alternative, the transmission 60 may have the structure shown in fig. 7. This structure differs from the above-described structure shown in fig. 6 only in the axial positions of the first gear pair 101 and the second gear pair 102.

(2) As shown in fig. 8, a heat transfer member 111 that is in close contact with the second coil end portion 33B of the stator coil 32 may be provided in the housing 14 of the rotary electric machine 10, so that heat is dissipated from the second coil end portion 33B via the heat transfer member 111. The heat transfer member 111 may be formed of a heat transferable material such as silicone rubber or grease. Further, the heat transfer member 111 may be provided in a ring shape along the second coil end portion 33B. Therefore, the heat dissipation from the second coil end portion 33B is promoted by the above-described heat transfer member 111.

Further, the heat transfer member 111 may be disposed in close contact with the case 14 and the second coil end portion 33B. In this case, heat dissipation from the second coil end portion 33B is further promoted by heat conduction from the second coil end portion 33B to the case 14 via the heat transfer member 111.

In addition, the heat transfer member 111 may be formed of a coolant such as lubricating oil. For example, lubricating oil may be provided in the case 14 so that the second coil end portion 33B is immersed in the lubricating oil. Alternatively, in the housing 14, the lubricating oil may be sprinkled from the rotating shaft 11 or the rotor 12 onto the second coil end portion 33B as the rotating shaft 11 rotates.

(3) As shown in fig. 9, a plurality of protrusions 112 may be provided on the cover portion 16 of the housing 14 (in other words, on the portion of the housing 14 on the same axial side of the stator core 31 as the second coil end portion 33B) to promote heat dissipation from the housing 14 on the same axial side of the stator core 31 as the second coil end portion 33B (i.e., the axial side of the stator core 31 opposite the transmission 60).

For example, the protrusions 112 may be formed in an elongated shape (or a fin shape). Further, the protrusions 112 may be arranged parallel to each other in a radial manner or in a ring shape. In this case, the mechanical strength of the housing 14 can be increased by the protrusion 112.

Alternatively, the protrusion 112 may be formed in a columnar shape. Further, the protrusions 112 may be suitably distributed on the cover portion 16 of the housing 14.

(4) As shown in fig. 10, in the case 14 of the rotary electric machine 10, a temperature sensor 115 may also be provided on the same axial side of the stator core 31 as the second coil end portion 33B, the temperature sensor 115 serving as temperature detection means for detecting the temperature of the stator core 32.

Further, the control device 116 integrated with the rotary electric machine 10 may be provided on the same axial side of the stator core 31 as the second coil end portion 33B. Specifically, the control device 116 configured to control the operation of the rotary electric machine 10 may be positioned axially outside the cover portion 16 of the housing 14 and fixed to the cover portion 16. In addition, the control device 116 may include an inverter in which a plurality of semiconductor switching elements are provided.

As described previously, heat is more easily dissipated on the same axial side of the stator core 31 as the second coil end portion 33B (i.e., the axial side of the stator core 31 opposite the transmission 60) than on the same axial side of the stator core 31 as the first coil end portion 33A (i.e., the same axial side of the stator core 31 as the transmission 60). Therefore, positioning the temperature sensor 115 and the control device 116 on the same axial side of the stator core 31 as the second coil end portion 33B can maintain the performance of these devices 115, 116, and thus improve the reliability of the rotating electrical machine 10.

(5) In the above embodiment, the power transmission unit 61 and the differential 62 are housed in the case 63 of the transmission 60. Alternatively, only the power transmission unit 61 may be housed in the case 63 (i.e., the differential 62 is not housed).

Further, in the above embodiment, the power transmission unit 61 is of a gear type. Alternatively, the power transmission unit 61 may be a friction type (i.e., a transmission type that transmits power by surface friction).

(6) In the above embodiment, the housing 14 of the rotary electric machine 10 and the housing 63 of the transmission 60 are formed separately from each other first, and then joined together as a single piece.

Alternatively, the housing 14, 63 may be integrally formed as a single component.

(7) In the above-described embodiment, each phase winding of the stator coil 32 is formed of a plurality of substantially U-shaped electrical conductor segments 40.

Alternatively, each phase winding of the stator coil 32 may be formed of a plurality of sub-windings wound on the stator core 31 and connected in series with each other. In this case, each sub-winding is formed of a single wire having a substantially rectangular cross section. Each of the sub-windings is wound on the stator core 31 at a predetermined pitch to have a plurality of turn portions 42 on both sides in the axial direction of the stator core 31, the turn portions 42 being formed by bending. That is, each of the first coil end portion 33A and the second coil end portion 33B includes a turn 42 of the sub-winding. Further, the second coil end portion 33B also includes joints at each of which each corresponding pair of ends of the sub-winding is joined together. In addition, as in the above-described embodiment, the second coil end portion 33B is located on the opposite axial side of the stator core 31 from the transmission 60, while the first coil end portion 33A is located on the same axial side of the stator core 31 as the transmission 60.

(8) In the above-described embodiment, the stator coil 32 is a three-phase coil in which the U-phase winding, the V-phase winding, and the W-phase winding are star-connected (or Y-connected) to each other.

Alternatively, the U-phase winding, the V-phase winding, and the W-phase winding of the stator coil 32 may be delta-connected to each other.

Further, the number of phases of the stator coil 32 may alternatively be two or more than four.

(9) In the above-described embodiment, the rotary electric machine 10 is configured as an inner rotor type rotary electric machine in which the rotor 12 is located radially inside the stator 13.

Alternatively, the rotary electric machine 10 may be configured as an outer rotor type rotary electric machine in which the rotor is located radially outside the stator.