Patent Publication Number: US-2021194325-A1

Title: Rotary electric machine unit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of priority of Japanese Patent Application No. 2019-228478, filed on Dec. 18, 2019, the content of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a rotary electric machine unit mounted on an electric vehicle or the like. 
     BACKGROUND ART 
     In the related art, a rotary electric machine unit including a plurality of rotary electric machines has been known as a rotary electric machine unit mounted on an electric vehicle or the like. For example, JP-A-2009-254144 discloses a rotary electric machine unit including a first rotary electric machine having a first rotation axis extending in a horizontal direction and a second rotary electric machine having a second rotation axis extending in parallel with the first rotation axis. 
     In this type of rotary electric machine unit, a higher cooling efficiency is required in association with a higher output of the rotary electric machine. 
     However, in the rotary electric machine unit of JP-A-2009-254144, for example, when a cooling supply portion is provided above a second rotary electric machine (MG 2 ), refrigerant supplied from the cooling supply portion flows down to a differential unit (DF) after cooling the second rotary electric machine (MG 2 ). Therefore, since the refrigerant supplied from the cooling supply portion cools only the second rotary electric machine (MG 2 ) and does not cool the first rotary electric machine (MG 1 ), there is a limit to a cooling efficiency of the rotary electric machine unit. Therefore, it is desirable to further improve the cooling efficiency of the rotary electric machine unit. 
     SUMMARY 
     The present invention provides a rotary electric machine unit with an improved cooling efficiency. 
     According to an aspect of the present invention, there is provided a rotary electric machine unit including: a first rotary electric machine that has a first rotation axis extending in a horizontal direction, and includes a first rotor having a substantially annular shape and a first stator including a first stator core having a substantially annular shape surrounding an outer periphery of the first rotor and a first coil mounted on the first stator core; a second rotary electric machine that has a second rotation axis extending in parallel with the first rotation axis and positioned lower than the first rotation axis, and includes a second rotor having a substantially annular shape and a second stator including a second stator core having a substantially annular shape surrounding an outer periphery of the second rotor and a second coil mounted on the second stator core; a first rotation speed detection device that is arranged at a position overlapping with the first rotary electric machine as viewed from an axial direction, and configured to detect a rotation speed of the first rotary electric machine; a second rotation speed detection device that is arranged at a position overlapping with the second rotary electric machine as viewed from the axial direction, and configured to detect a rotation speed of the second rotary electric machine; and a refrigerant supply portion that is arranged at a position upper than the first rotation axis and overlapping with the first rotary electric machine in the axial direction and overlapping with the first rotary electric machine in a left-right direction orthogonal to an upper-lower direction and the axial direction, and configured to supply refrigerant to the first rotary electric machine, where: the first stator core includes a first end surface and a second end surface in the axial direction; the first coil includes a plurality of substantially U-shaped first segment conductors, and includes first coil end portions protruding axially outward from the first end surface and the second end surface of the first stator core; each of the first segment conductors includes a pair of leg portions extending in parallel with each other and having a first end portion and a second end portion, and a curved portion connecting the second end portions of the pair of leg portions, and the first end portion of the leg portion is conducted to the first end portion of the leg portion of different first segment conductor; the first coil end portions include a first open-side coil end portion in which the first end portions of the leg portions of the first segment conductor protrude axially outward from the first end surface of the first stator core, and a first close-side coil end portion in which the curved portion of the first segment conductor protrudes axially outward from the second end surface of the first stator core: the second stator core includes a first end surface and a second end surface in the axial direction, the second coil includes a plurality of substantially U-shaped second segment conductors, and includes second coil end portions protruding axially outward from the first end surface and the second end surface of the second stator core; the second segment conductor includes a pair of leg portions extending in parallel with each other and having a first end portion and a second end portion, and a curved portion connecting the second end portions of the pair of leg portions, and the first end portion of the leg portion is conducted to the first end portion of the leg portion of different second segment conductor; the second coil end portions include a second open-side coil end portion in which the first end portions of the leg portions of the first segment conductor protrude axially outward from the first end surface of the second stator core, and a second close-side coil end portion in which the curved portion of the second segment conductor protrudes axially outward from the second end surface of the second stator core; the first rotary electric machine and the second rotary electric machine are arranged such that the first open-side coil end portion and the second open-side coil end portion are on one axial end side in the axial direction; and the first rotation speed detection device and the second rotation speed detection device are arranged on the one axial end side of the first rotary electric machine and the second rotary electric machine in the axial direction. 
     According to the aspect of the present invention, the cooling efficiency of the rotary electric machine unit is improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view of a rotary electric machine unit according to an embodiment of the present invention as viewed from a front side. 
         FIG. 2  is a perspective view of main parts of a first segment conductor and a second segment conductor mounted on a first stator and a second stator in a first rotary electric machine and a second rotary electric machine of  FIG. 1 . 
         FIG. 3  is a view of the first stator and the second stator on which the first segment conductor and the second segment conductor are mounted, as viewed from the outside in a radial direction. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     (Overall Configuration of Rotary Electric Machine Unit) 
     As shown in  FIG. 1 , the rotary electric machine unit  1  according to the present embodiment includes a first rotary electric machine  10  having a first rotation axis CL 1  extending in a horizontal direction, a second rotary electric machine  20  having a second rotation axis CL 2  extending in parallel with the first rotation axis CL 1 , a first resolver  30  for detecting a rotation speed of the first rotary electric machine  10 , a second resolver  40  for detecting a rotation speed of the second rotary electric machine  20 , a first refrigerant supply portion  50  for supplying refrigerant to the first rotary electric machine  10 , a second refrigerant supply portion  60  for supplying refrigerant to the second rotary electric machine  20 , and a rotary electric machine housing  70 . The rotary electric machine housing  70  includes a rotary electric machine accommodating portion  700 . The first rotary electric machine  10 , the second rotary electric machine  20 , the first resolver  30 , the second resolver  40 , the first refrigerant supply portion  50 , and the second refrigerant supply portion  60  are accommodated in the rotary electric machine accommodating portion  700  of the rotary electric machine housing  70 . 
     In the present specification or the like, a direction parallel to the first rotation axis CL 1  of the first rotary electric machine  10  and the second rotation axis CL 2  of the second rotary electric machine  20  is referred to as an axial direction of the rotary electric machine unit  1 . In addition, in the present specification or the like, in order to simplify and clarify the description, an axial direction is defined as a front-rear direction, and a direction orthogonal to both an upper-lower direction and the front-rear direction (axial direction) is defined as a left-right direction. However, these directions are independent of a direction of a product on which the rotary electric machine unit  1  is mounted. That is, for example, when the rotary electric machine unit  1  is mounted on a vehicle, the front-rear direction of the rotary electric machine unit  1  may coincide with the front-rear direction of the vehicle, may be the left-right direction of the vehicle, or may be a horizontal direction inclined from the front-rear direction and the left-right direction of the vehicle. In the drawings, a front side of the rotary electric machine unit  1  is denoted by Fr, a rear side thereof is denoted by Rr, a left side thereof is denoted by L, a right side thereof is denoted by R, an upper side thereof is denoted by U, and a lower side thereof is denoted by D, respectively. 
     &lt;Rotary Electric Machine&gt; 
     The first rotary electric machine  10  is an electric motor that outputs power. The first rotary electric machine  10  includes a first rotary shaft  11 , a substantially annular first rotor  12  press-fitted to the first rotary shaft  11 , and a first stator  13  arranged so as to surround an outer periphery of the first rotor  12  and fixed to the rotary electric machine housing  70 . The first stator  13  includes a first stator core  14  having a substantially annular shape surrounding the outer periphery of the first rotor  12 , and a first coil  15  formed of three phases of a U-phase, a V-phase, and a W-phase mounted on the first stator core  14 . The first stator  13  is fixed to the rotary electric machine housing  70  by a fastening member  16 . The first stator core  14  includes a first end surface  14   a  and a second end surface  14   b  in the axial direction (see  FIG. 3 ). The first coil  15  includes first coil end portions  15   a  protruding axially outward from the first end surface  14   a  and the second end surface  14   b  of the first stator core  14 . The first coil end portion  15   a  has a substantially annular shape centered on the first rotation axis CL 1  as viewed from the axial direction, and includes a left end portion  15   a L and a right end portion  15   a R at a central portion in the upper-lower direction, that is, at substantially the same position as the first rotation axis CL 1  in the upper-lower direction. 
     The second rotary electric machine  20  is a generator that generates power. The second rotary electric machine  20  includes a second rotary shaft  21 , a substantially annular second rotor  22  press-fitted to the second rotary shaft  21 , and a second stator  23  arranged so as to surround an outer periphery of the second rotor  22  and fixed to the rotary electric machine housing  70 . The second stator  23  includes a second stator core  24  having a substantially annular shape surrounding the outer periphery of the second rotor  22 , and a second coil  25  formed of three phases of a U-phase, a V-phase, and a W-phase mounted on the second stator core  24 . The second stator  23  is fixed to the rotary electric machine housing  70  by a fastening member  26 . The second stator core  24  includes a first end surface  24   a  and a second end surface  24   b  in the axial direction (see  FIG. 3 ). The second coil  25  includes second coil end portions  25   a  protruding axially outward from the first end surface  24   a  and the second end surface  24   b  of the second stator core  24 . The second coil end portion  25   a  has a substantially annular shape centered on the second rotation axis CL 2  as viewed from the axial direction, and includes a left end portion  25   a L and a right end portion  25   a R at a central portion in the upper-lower direction, that is, at substantially the same position as the second rotation axis CL 2  in the upper-lower direction. 
     Details of the configurations of the first stator  13  and the second stator  23  will be described later. 
     &lt;Arrangement of Rotary Electric Machine&gt; 
     The first rotary electric machine  10  and the second rotary electric machine  20  are arranged so as to overlap with each other in the axial direction. 
     The second rotation axis CL 2  of the second rotary electric machine  20  is positioned lower than the first rotation axis CL 1  of the first rotary electric machine  10 . 
     The first rotary electric machine  10  and the second rotary electric machine  20  are arranged so as to partially overlap with each other in the upper-lower direction. Accordingly, a dimension of the rotary electric machine unit  1  in the upper-lower direction can be reduced, and the rotary electric machine unit  1  can be reduced in a size. 
     The second rotary electric machine  20  is arranged such that the second coil end portion  25   a  overlaps with the left end portion  15   a L of the first coil end portion  15   a  of the first rotary electric machine  10  in the left-right direction as viewed from the axial direction. 
     The second rotary electric machine  20  is arranged such that the second rotation axis CL 2  does not overlap with the first rotary electric machine  10  in the left-right direction as viewed from the axial direction. 
     &lt;Resolver&gt; 
     The first resolver  30  is arranged at a position overlapping with the first rotary electric machine  10  as viewed from the axial direction. The first resolver  30  includes a first resolver rotor  31  attached to the first rotary shaft  11  and a first resolver stator  32  attached to the rotary electric machine housing  70 . In the present embodiment, the first resolver  30  is provided in front of the first rotor  12  and the first stator  13  of the first rotary electric machine  10 . 
     The first resolver rotor  31  is formed of, for example, a tubular member (electromagnetic steel pipe) of electromagnetic steel. The electromagnetic steel pipe is a steel pipe excellent in magnetic characteristics. The first resolver rotor  31  is formed with a thick portion  31   a  having a long radial length and a thin portion  31   b  having a short radial length. The first resolver rotor  31  is fixed to the first rotary shaft  11  by, for example, press-fitting. 
     The first resolver stator  32  is arranged opposite to an outer side in the radial direction of the first resolver rotor  31 , and includes a stator portion  33  having a substantially annular shape centered on the first rotation axis CL 1 , and a telecom connector portion  34  extending radially outward from the stator portion  33  and protruding forward in the axial direction. In the present embodiment, the telecom connector portion  34  extends downward from the stator portion  33 . 
     An inner peripheral surface of the stator portion  33  is provided with a plurality of detection portions  331  formed so as to extend radially inward and arranged in a ring shape in a peripheral direction. A coil (not shown) is arranged in each of the detection portions  331  inside the stator portion  33 . 
     A plurality of fastening portions  334  are provided on an outer peripheral surface of the stator portion  33  so as to extend radially outward and have bolt insertion holes  333  penetrating in a central axial direction. In the present embodiment, three fastening portions  334  are provided at substantially equal intervals in the peripheral direction on the outer peripheral surface of the stator portion  33 . 
     By inserting fastening bolts into the bolt insertion holes  333  provided in the respective fastening portions  334  of the first resolver stator  32  and fastening the fastening bolts to the rotary electric machine housing  70 , the first resolver stator  32  is fixed to the rotary electric machine housing  70 . 
     The telecom connector portion  34  includes an extension portion  341  extending radially outward from the outer peripheral surface of the stator portion  33  to the top and an external connection portion  342  protruding forward from the extension portion  341 . The telecom connector portion  34  is formed integrally with the stator portion  33 . 
     The external connection portion  342  includes a terminal portion (not shown) electrically connected to a coil arranged inside the stator portion  33 . The external connection portion  342  protrudes to the outside of the rotary electric machine housing  70 , and electric power is supplied from the outside of the rotary electric machine unit  1  to the coil arranged inside the stator portion  43  via the terminal portion by connecting a wire harness or the like extending from a control unit or the like outside the rotary electric machine unit  1  to the external connection portion  342 . 
     For example, when a current is supplied to the first coil  15  of the first stator  13  of the first rotary electric machine  10 , the first rotor  12  rotates, and the first rotary shaft  11  and the first resolver rotor  31  rotate in accordance with the rotation of the first rotor  12 . 
     When the first resolver rotor  31  rotates, a gap between the first resolver rotor  31  and the first resolver stator  32  is changed by the thick portion  31   a  and the thin portion  31   b  of the first resolver rotor  31 . When a current is supplied to the coil of the first resolver stator  32 , a magnetic field is formed, and an amount of magnetic fluxes changes from place to place as the gap between the first resolver rotor  31  and the first resolver stator  32  changes in accordance with the rotation of the first resolver rotor  31 . Rotation speeds of the first rotary shaft  11  and the first rotor  12 , that is, the rotation speed of the first rotary electric machine  10  can be detected by detecting a change in the magnetic flux by the detection portion  331  of the first resolver stator  32 . 
     The second resolver  40  is arranged at a position overlapping with the second rotary electric machine  20  as viewed from the axial direction. The second resolver  40  includes a second resolver rotor  41  attached to the second rotary shaft  21  and a second resolver stator  42  attached to the rotary electric machine housing  70 . In the present embodiment, the second resolver  40  is provided in front of the second rotor  22  and the second stator  23  of the second rotary electric machine  20 . 
     The second resolver rotor  41  is formed of, for example, a tubular member (electromagnetic steel pipe) of electromagnetic steel. The electromagnetic steel pipe is a steel pipe excellent in magnetic characteristics. The second resolver rotor  41  is formed with a thick portion  41   a  having a long radial length and a thin portion  41   b  having a short radial length. The second resolver rotor  41  is fixed to the second rotary shaft  21  by, for example, press-fitting. 
     The second resolver stator  42  is arranged opposite to an outer side in the radial direction of the second resolver rotor  41 , and includes a stator portion  43  having a substantially annular shape centered on the second rotation axis CL 2 , and a telecom connector portion  44  extending radially outward from the stator portion  43  and protruding forward in the axial direction. In the present embodiment, the telecom connector portion  44  extends from the stator portion  43  in a lower left direction. 
     An inner peripheral surface of the stator portion  43  is provided with a plurality of detection portions  431  formed so as to extend radially inward and arranged in a ring shape in the peripheral direction. A coil (not shown) is arranged in each of the detection portions  431  inside the stator portion  43 . 
     A plurality of fastening portions  434  are formed on an outer peripheral surface of the stator portion  43  so as to extend radially outward and have bolt insertion holes  433  penetrating in the central axial direction. In the present embodiment, three fastening portions  434  are provided at substantially equal intervals in the peripheral direction on the outer peripheral surface of the stator portion  43 . 
     By inserting fastening bolts into the bolt insertion holes  433  provided in the respective fastening portions  434  of the second resolver stator  42  and fastening the fastening bolts to the rotary electric machine housing  70 , the second resolver stator  42  is fixed to the rotary electric machine housing  70 . 
     The telecom connector portion  44  includes an extension portion  441  extending radially outward from the outer peripheral surface of the stator portion  43  to the lower left and an external connection portion  442  protruding forward from the extension portion  441 . The telecom connector portion  44  is formed integrally with the stator portion  43 . 
     The external connection portion  442  includes a terminal portion (not shown) electrically connected to a coil arranged inside the stator portion  43 . The external connection portion  442  protrudes to the outside of the rotary electric machine housing  70 , and electric power is supplied from the outside of the rotary electric machine unit  1  to the coil arranged inside the stator portion  43  via the terminal portion by connecting a wire harness or the like extending from a control unit or the like outside the rotary electric machine unit  1  to the external connection portion  442 . 
     For example, when the second rotor  22  is rotated by power supplied from an external drive source of the rotary electric machine unit  1 , the second rotary shaft  21  and the second resolver rotor  41  rotate in accordance with the rotation of the second rotor  22 . 
     When the second resolver rotor  41  rotates, a gap between the second resolver rotor  41  and the second resolver stator  42  is changed by the thick portion  41   a  and the thin portion  41   b  of the second resolver rotor  41 . When a current is supplied to the coil of the second resolver stator  42 , a magnetic field is formed, and an amount of magnetic fluxes changes from place to place as the gap between the second resolver rotor  41  and the second resolver stator  42  changes in accordance with the rotation of the second resolver rotor  41 . Rotation speeds of the second rotary shaft  21  and the second rotor  22 , that is, the rotation speed of the second rotary electric machine  20  can be detected by detecting a change in the magnetic flux by the detection portion  431  of the second resolver stator  42 . 
     &lt;Refrigerant Supply Portion&gt; 
     The first refrigerant supply portion  50  includes a pair of first refrigerant supply pipes  51  provided on a left side and a right side of the first rotation axis CL 1  of the first rotary electric machine  10  at positions upper than the first rotation axis CL 1  of the first rotary electric machine  10  and overlapping with the first rotary electric machine  10  in the left-right direction. Each of the pair of first refrigerant supply pipes  51  extends in parallel with the first rotation axis CL 1  from a front surface to a rear surface of the rotary electric machine accommodating portion  700 . 
     Refrigerant discharge holes  52  are provided in the pair of first refrigerant supply pipes  51  at positions overlapping with the first rotary electric machine  10  in the axial direction. Refrigerant such as an automatic transmission fluid (ATF) is supplied to the pair of first refrigerant supply pipes  51  from a refrigerant supply device (not shown). The refrigerant supplied from the refrigerant supply device to the first refrigerant supply pipe  51  is discharged (including dropping and jetting) from the refrigerant discharge hole  52  and supplied to the first rotary electric machine  10  to cool the first rotary electric machine  10 . 
     In the present embodiment, a pair of front and rear refrigerant discharge holes  52  are provided at positions overlapping with the first coil end portions  15   a  of the first coil  15 , which protrude axially outward from both axial end surfaces of the first stator core  14  of the first rotary electric machine  10  in the axial direction. The refrigerant supplied to the first refrigerant supply pipe  51  and discharged from the refrigerant discharge hole  52  is supplied to the first coil end portions  15   a  on both axial sides of the first rotary electric machine  10 , and cools the first coil end portions  15   a.    
     The second refrigerant supply portion  60  includes a pair of second refrigerant supply pipes  61  provided on a left side and a right side of the second rotation axis CL 2  of the second rotary electric machine  20  at positions upper than the second rotation axis CL 2  of the second rotary electric machine  20  and overlapping with the second rotary electric machine  20  in the left-right direction. Each of the pair of second refrigerant supply pipes  61  extends in parallel with the second rotation axis CL 2  from the front surface to the rear surface of the rotary electric machine accommodating portion  700 . 
     Refrigerant discharge holes  62  are provided in the pair of second refrigerant supply pipes  61  at positions overlapping with the second rotary electric machine  20  in the axial direction. Refrigerant such as an automatic transmission fluid (ATF) is supplied to the pair of second refrigerant supply pipes  61  from a refrigerant supply device (not shown). The refrigerant supplied from the refrigerant supply device to the second refrigerant supply pipe  61  is discharged (including dropping and jetting) from the refrigerant discharge hole  62  and supplied to the second rotary electric machine  20  to cool the second rotary electric machine  20 . 
     In the present embodiment, a pair of front and rear refrigerant discharge holes  62  are provided at positions overlapping with the second coil end portions  25   a  of the second coil  25 , which protrude axially outward from both axial end surfaces of the second stator core  24  of the second rotary electric machine  20  in the axial direction. The refrigerant supplied to the second refrigerant supply pipe  61  and discharged from the refrigerant discharge hole  62  is supplied to the second coil end portions  25   a  on both axial sides of the second rotary electric machine  20 , and cools the second coil end portions  25   a.    
     &lt;Flow of Refrigerant&gt; 
     Most of the refrigerant discharged from the refrigerant discharge hole  52  of the first refrigerant supply pipe  51  flows downward in the left-right direction along the first coil end portion  15   a  of the first coil  15  while flowing downward. Further, most of the refrigerant that has reached the left end portion  15   a L and the right end portion  15   a R positioned at the central portion in the upper-lower direction of the first coil end portion  15   a  is separated from the first coil end portion  15   a  and flows down substantially vertically downward due to gravity. 
     On the other hand, at a front side of the first rotary electric machine  10 , a part of the refrigerant discharged from the refrigerant discharge hole  52  of the first refrigerant supply pipe  51  passes through the first coil end portion  15   a  of the first coil  15 , a part thereof flows to the first resolver stator  32 , and a part thereof flows to the first rotary shaft  11 , a front side surface of the first rotor  12  and the first resolver rotor  31 . 
     The refrigerant that has flowed to the first resolver stator  32  flows through the first resolver stator  32 , partly flows to the second rotary electric machine  20 , and partly flows downward from a lower end of the first resolver stator  32 , and is supplied to a lower end portion of the first coil end portion  15   a . In addition, the refrigerant that has flowed to the first rotary shaft  11 , the front side surface of the first rotor  12 , and the first resolver rotor  31  is scattered radially outward due to the rotation of the first resolver rotor  31  or the like, and is supplied to the first coil end portion  15   a.    
     Most of the refrigerant discharged from the refrigerant discharge hole  62  of the second refrigerant supply pipe  61  flows downward in the left-right direction along the second coil end portion  25   a  of the second coil  25  while flowing downward. Further, most of the refrigerant that has reached the left end portion  25   a L and the right end portion  25   a R positioned at the central portion in the upper-lower direction of the second coil end portion  25   a  is separated from the second coil end portion  25   a  and flows down substantially vertically downward due to gravity. 
     On the other hand, at a front side of the second rotary electric machine  20 , a part of the refrigerant discharged from the refrigerant discharge hole  62  of the second refrigerant supply pipe  61  passes through the second coil end portion  25   a  of the second coil  25 , and a part thereof flows to the second resolver stator  42 , and a part thereof flows to the second rotary shaft  21 , a front side surface of the second rotor  22  and the second resolver rotor  41 . 
     The refrigerant that has flowed to the second resolver stator  42  flows through the second resolver stator  42 , and partly flows downward from a lower end of the first resolver stator  32 , and is supplied to the lower end portion of the second coil end portion  25   a . In addition, the refrigerant that has flowed to the second rotary shaft  21 , the front side surface of the second rotor  22 , and the second resolver rotor  41  is scattered radially outward due to the rotation of the second resolver rotor  41  or the like, and is supplied to the second coil end portion  25   a.    
     In the present embodiment, the second rotation axis CL 2  of the second rotary electric machine  20  is positioned lower than the first rotation axis CL 1  of the first rotary electric machine  10 , that is, the second rotary electric machine  20  is positioned lower than the first rotary electric machine  10 . Therefore, a part of the refrigerant discharged from the refrigerant discharge hole  52  of the first refrigerant supply pipe  51  is supplied to the second rotary electric machine  20  through the first resolver stator  32 . Therefore, in addition to the refrigerant discharged from the refrigerant discharge hole  62  of the second refrigerant supply pipe  61 , a part of the refrigerant discharged from the refrigerant discharge hole  52  of the first refrigerant supply pipe  51  is also supplied to the second rotary electric machine  20 . As a result, in the rotary electric machine unit  1 , a cooling efficiency of the second rotary electric machine  20  can be improved without lowering a cooling efficiency of the first rotary electric machine  10 , so that a cooling efficiency of the rotary electric machine unit  1  is improved. 
     In addition, since the first rotary electric machine  10  is an electric motor that outputs power and the second rotary electric machine  20  is a generator that generates power, the electric motor required to have a high cooling effect is arranged above, and the generator required to have a low cooling effect than the electric motor is arranged below. Accordingly, the refrigerant having a low temperature discharged from the refrigerant discharge hole  52  of the first refrigerant supply pipe  51  can be supplied to the first rotary electric machine  10 , which is an electric motor, and the second rotary electric machine  20 , which is a generator, has a cooling effect even with the refrigerant after passing through the electric motor, thereby further improving the cooling efficiency of the rotary electric machine unit  1 . 
     The second rotary electric machine  20  is arranged such that the second coil end portion  25   a  overlaps with the left end portion  15   a L of the first coil end portion  15   a  of the first rotary electric machine  10  in the left-right direction as viewed from the axial direction. Therefore, the refrigerant discharged from the refrigerant discharge hole  52  of the first refrigerant supply pipe  51 , flowing along the first coil end portion  15   a  of the first coil  15 , and flowing down from the left end portion  15   a L of the first coil end portion  15   a  is supplied to the second coil end portion  25   a  of the second rotary electric machine  20 . As a result, more refrigerant discharged from the refrigerant discharge hole  52  of the first refrigerant supply pipe  51  can be supplied to the second coil end portion  25   a  of the second rotary electric machine  20 , so that the cooling efficiency of the rotary electric machine unit  1  is further improved. 
     Since the second rotary electric machine  20  is arranged such that the second rotation axis CL 2  does not overlap with the first rotary electric machine  10  in the left-right direction as viewed from the axial direction, the first rotary electric machine  10  does not exist at an upper end portion of the second rotary electric machine  20 . Therefore, the second refrigerant supply pipe  61  of the second refrigerant supply portion  60  can be easily arranged above the upper end portion of the second rotary electric machine  20 . As a result, the refrigerant having a lower temperature from the second refrigerant supply portion  60  that has not passed through the first rotary electric machine  10  can be supplied from the upper end portion of the second rotary electric machine  20 , so that the cooling efficiency of the second rotary electric machine  20  can be further improved and the cooling efficiency of the rotary electric machine unit  1  can be further improved. 
     &lt;Details of Configuration of Stator&gt; 
     As shown in  FIGS. 2 and 3 , the first stator core  14  has a substantially annular shape, and includes a plurality of first teeth  141  protruding radially inward at predetermined intervals along the peripheral direction, and a plurality of first slots  142  that are spaces between adjacent first teeth  141  in the peripheral direction. The first stator core  14  includes a first end surface  14   a  and a second end surface  14   b  in the axial direction. 
     The first coil  15  is formed of a plurality of substantially U-shaped first segment conductors  150  respectively inserted into the plurality of first slots  142 . 
     The first segment conductor  150  includes a pair of leg portions  151  extending in parallel with each other, and a curved portion  152  connecting the pair of leg portions  151 , and has a substantially U shape. Each of the pair of leg portions  151  includes a first end portion  151   a  and a second end portion  151   b , and the curved portion  152  connects the second end portions  151   b  of the pair of leg portions  151 . The first segment conductor  150  is arranged such that the pair of leg portions  151  are respectively inserted into different first slots  142  of the first stator core  14 , the curved portions  152  protrude axially outward from the second end surface  14   b  of the first stator core  14 , and the first end portions  151   a  of the pair of leg portions  151  protrude axially outward from the first end surface  14   a  of the first stator core  14 . 
     Protruding portions of the pair of leg portions  151  on a first end portion  151   a  side, which protrude axially outward from the first end surface  14   a  of the first stator core  14 , are bent in the peripheral direction of the first stator core  14  by a jig (not shown) holding front end portions of the first end portions  151   a  and rotating relative to the first stator core  14  in the peripheral direction while approaching the first stator core  14  in the axial direction. As a result, the protruding portions of the first end portions  151   a  of the pair of leg portions  151  are formed with oblique portions  153  that bend and extend in a direction toward each other or away from each other in the peripheral direction of the first stator core  14  and front end portions  154  that extend outward in the axial direction of the first stator core  14  from front ends of the oblique portions  153 , which are front end portions of the first end portions  151   a  held by the jig, respectively. 
     The first segment conductor  150  formed in this manner includes a lap-wound segment conductor  150 A in which the oblique portions  153  are skewed in a direction in which the front end portions  154  formed on the first end portions  151   a  of the pair of leg portions  151  approach each other, and a wave-wound segment conductor  150 B in which the oblique portions  153  are skewed in a direction in which the front end portions  154  formed on the first end portions  151   a  of the pair of leg portions  151  are separated from each other. 
     A plurality of lap-wound segment conductors  150 A and wave-wound segment conductors  150 B are inserted into the first slots  142 . At this time, the plurality of lap-wound segment conductors  150 A and wave-wound segment conductors  150 B are arranged such that the leg portions  151  are arranged in a row in the radial direction in the first slot  142 . 
     The front end portions  154  of the lap-wound segment conductor  150 A and the wave-wound segment conductor  150 B inserted into the first slots  142  are joined by, for example, laser welding to the front end portions  154  of the lap-wound segment conductor  150 A or the wave-wound segment conductor  150 B inserted into the different first slots  142  to be conductive. 
     In this way, the plurality of first segment conductors  150  (the lap-wound segment conductor  150 A and wave-wound segment conductor  150 B) are inserted into the plurality of first slots  142  provided in the first stator core  14 , and the respective front end portions  154  are joined and conducted to the front end portions  154  of the different first segment conductors  150 , thereby forming the first coil  15 . 
     The oblique portions  153  and the front end portions  154  of each of the first segment conductors  150  form first open-side coil end portions  15   al  protruding axially outward from the first end surface  14   a  of the first stator core  14 . The curved portion  152  of each of the first segment conductors  150  forms a first close-side coil end portion  15   a   2  protruding axially outward from the second end surface  14   b  of the first stator core  14 . 
     In this manner, the first coil end portion  15   a  includes the first open-side coil end portion  15   al  and the first close-side coil end portion  15   a   2 . 
     Similarly, the second stator core  24  has a substantially annular shape, and includes a plurality of second teeth  241  protruding radially inward at predetermined intervals along the peripheral direction, and a plurality of second slots  242  that are spaces between adjacent second teeth  241  in the peripheral direction. The second stator core  24  includes a first end surface  24   a  and a second end surface  24   b  in the axial direction. 
     The second coil  25  is formed of a plurality of substantially U-shaped second segment conductors  250  respectively inserted into the plurality of second slots  242 . 
     The second segment conductor  250  includes a pair of leg portions  251  extending in parallel with each other, and a curved portion  252  connecting the pair of leg portions  251 , and has a substantially U shape. Each of the pair of leg portions  251  includes a first end portion  251   a  and a second end portion  251   b , and the curved portion  252  connects the second end portions  251   b  of the pair of leg portions  251 . The second segment conductor  250  is arranged such that the pair of leg portions  251  are respectively inserted into different second slots  242  of the second stator core  24 , and the curved portions  252  protrude axially outward from the second end surface  24   b  of the second stator core  24 , and the first end portions  251   a  of the pair of leg portions  251  protrude axially outward from the first end surface  24   a  of the second stator core  24 . 
     Protruding portions of the pair of leg portions  251  on a first end portion  251   a  side, which protrude axially outward from the first end surface  24   a  of the second stator core  24 , are bent in the peripheral direction of the second stator core  24  by a jig (not shown) holding front end portions of the first end portions  251   a  and rotating relative to the second stator core  24  in the peripheral direction while approaching the second stator core  24  in the axial direction. As a result, the protruding portions of the first end portions  251   a  of the pair of leg portions  251  are formed with oblique portion  253  that bend and extend in a direction toward each other or away from each other in the peripheral direction of the second stator core  24  and front end portions  254  that extend outward in the axial direction of the second stator core  24  from front ends of the oblique portions  153 , which are front end portions of the first end portions  251   a  held by the jig, respectively. 
     The second segment conductor  250  formed in this manner includes a lap-wound segment conductor  250 A in which the oblique portions  253  are skewed in a direction in which the front end portions  254  formed at the first end portions  251   a  of the pair of leg portions  251  approaches each other, and a wave-wound segment conductor  250 B in which the oblique portions  253  are skewed in a direction in which the front end portions  254  formed on the first end portions  251   a  of the pair of leg portions  251  are separated from each other. 
     A plurality of lap-wound segment conductors  250 A and wave-wound segment conductors  250 B are inserted into the second slots  242 . At this time, the plurality of lap-wound segment conductors  250 A and the wave-wound segment conductors  250 B are arranged such that the leg portions  251  are arranged in a row in the radial direction in the second slot  242 . 
     The front end portions  254  of the lap-wound segment conductor  250 A and the wave-wound segment conductor  250 B inserted into the second slots  242  are joined by, for example, laser welding to the front end portions  254  of the lap-wound segment conductor  250 A or the wave-wound segment conductor  250 B inserted into the different second slots  242  to be conductive. 
     In this way, the plurality of second segment conductors  250  (the lap-wound segment conductor  250 A and wave-wound segment conductor  250 B) are inserted into the plurality of second slots  242  provided in the second stator core  24 , and the respective front end portions  254  are joined and conducted to the front end portions  254  of the different second segment conductors  250 , thereby forming the second coil  25 . 
     The oblique portions  253  and the front end portions  254  of each of the second segment conductors  250  form second open-side coil end portion  25   al  protruding axially outward from the first end surface  24   a  of the second stator core  24 . The curved portion  252  of each of the second segment conductors  250  forms a second close-side coil end portion  25   a   2  protruding axially outward from the second end surface  24   b  of the second stator core  24 . 
     In this manner, the second coil end portion  25   a  includes the second open-side coil end portion  25   al  and the second close-side coil end portion  25   a   2 . 
     In the first coil  15  and the second coil  25  formed in this manner, since the first open-side coil end portion  15   al  and the second open-side coil end portion  25   al  are formed with the front end portions  154 ,  254  for joining different first segment conductors  150  and the second segment conductors  250 , respectively, the first open-side coil end portion  15   al  and the second open-side coil end portion  25   al  protrude axially toward an outer side than the first close-side coil end portion  15   a   2  and the second close-side coil end portion  25   a   2 . Further, since the first open-side coil end portion  15   al  and the second open-side coil end portion  25   al  are conducted to the different first segment conductor  150  and second segment conductor  250  by joining, the first open-side coil end portion  15   al  and the second open-side coil end portion  25   al  have higher electric resistance than the first close-side coil end portion  15   a   2  and the second close-side coil end portion  25   a   2 . Therefore, when the first rotary electric machine  10  and the second rotary electric machine  20  are driven, the first open-side coil end portion  15   al  and the second open-side coil end portion  25   al  generate a larger amount of heat than the first close-side coil end portion  15   a   2  and the second close-side coil end portion  25   a   2 . 
     Returning to  FIG. 1 , the first rotary electric machine  10  and the second rotary electric machine  20  are arranged such that the first open-side coil end portion  15   al  and the second open-side coil end portion  25   al  are on the front side in the axial direction. The first resolver  30  and the second resolver  40  are arranged on the front side of the first rotary electric machine  10  and the second rotary electric machine  20  in the axial direction. As described above, the first open-side coil end portion  15   al  and the second open-side coil end portion  25   al  of the first rotary electric machine  10  and the second rotary electric machine  20  are arranged on the same side in the axial direction, and the first resolver  30  and the second resolver  40  are both arranged on the same side as the side where the first open-side coil end portion  15   al  and the second open-side coil end portion  25   al  are arranged in the axial direction. 
     Therefore, the refrigerant flowing downward from the lower end of the first resolver stator  32  through the first resolver stator  32  is supplied to a lower end portion of the first open-side coil end portion  15   al  having a larger heat generation amount. In addition, the refrigerant that has flowed into the first rotary shaft  11 , the front side surface of the first rotor  12 , and the first resolver rotor  31  is scattered radially outward due to rotation of the first resolver rotor  31  or the like, and is supplied to the first open-side coil end portion  15   al  having a larger heat generation amount. 
     As a result, more refrigerant can be supplied to the first open-side coil end portion  15   al  having a larger heat generation amount, so that the cooling efficiency of the rotary electric machine unit  1  is further improved. 
     Similarly, the refrigerant flowing downward from the lower end of the second resolver stator  42  through the second resolver stator  42  is supplied to a lower end portion of the second open-side coil end portion  25   al  having a higher heat generation amount. Further, the refrigerant that has flowed into the second rotary shaft  21 , the front side surface of the second rotor  22 , and the second resolver rotor  41  is scattered radially outward due to the rotation of the second resolver rotor  41  or the like, and is supplied to the second open-side coil end portion  25   al  having a larger heat generation amount. 
     Further, the refrigerant discharged from the refrigerant discharge hole  52  of the first refrigerant supply pipe  51  and supplied to the second rotary electric machine  20  through the first resolver stator  32  is supplied to the second open-side coil end portion  25   al  having a higher heat generation amount. 
     As a result, more refrigerant can be supplied to the second open-side coil end portion  25   al  having a higher heat generation amount, so that the cooling efficiency of the rotary electric machine unit  1  is further improved. 
     Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and modifications, improvements, or the like can be made as appropriate. 
     At least the following matters are described in the present specification. Although corresponding constituent elements or the like in the above embodiment are shown in parentheses, the present invention is not limited thereto. 
     (1) A rotary electric machine unit (rotary electric machine unit  1 ) including: 
     a first rotary electric machine (first rotary electric machine  10 ) that has a first rotation axis (first rotation axis CL 1 ) extending in a horizontal direction, and includes a first rotor (first rotor  12 ) having a substantially annular shape and a first stator (first stator  13 ) including a first stator core (stator core  14 ) having a substantially annular shape surrounding an outer periphery of the first rotor and a first coil (first coil  15 ) mounted on the first stator core; 
     a second rotary electric machine (second rotary electric machine  20 ) that has a second rotation axis (second rotation axis CL 2 ) extending in parallel with the first rotation axis and positioned lower than the first rotation axis, and includes a second rotor (second rotor  22 ) having a substantially annular shape and a second stator (second stator  23 ) including a second stator core (second stator core  24 ) having a substantially annular shape surrounding an outer periphery of the second rotor and a second coil (second coil  25 ) mounted on the second stator core; 
     a first rotation speed detection device (first resolver  30 ) that is arranged at a position overlapping with the first rotary electric machine as viewed from an axial direction, and configured to detect a rotation speed of the first rotary electric machine; 
     a second rotation speed detection device (second resolver  40 ) that is arranged at a position overlapping with the second rotary electric machine as viewed from the axial direction and configured to detect a rotation speed of the second rotary electric machine; and 
     a refrigerant supply portion (first refrigerant supply portion  50 ) that is arranged at a position upper than the first rotation axis and overlapping with the first rotary electric machine in the axial direction and overlapping with the first rotary electric machine in a left-right direction orthogonal to an upper-lower direction and the axial direction, and configured to supply refrigerant to the first rotary electric machine, where: 
     the first stator core includes a first end surface (first end surface  14   a ) and a second end surface (second end surface  14   b ) in the axial direction; 
     the first coil includes a plurality of substantially U-shaped first segment conductors (first segment conductors  150 ), and includes first coil end portions (first coil end portion  15   a ) protruding axially outward from the first end surface and the second end surface of the first stator core: 
     each of the first segment conductors includes a pair of leg portions (leg portions  151 ) extending in parallel with each other and having a first end portion (first end portion  151   a ) and a second end portion (second end portion  151   b ) and a curved portion (curved portion  152 ) connecting the second end portions of the pair of leg portions, and the first end portion of the leg portion is conducted to the first end portion of the leg portion of different first segment conductor: 
     the first coil end portions include a first open-side coil end portion (first open-side coil end portion  15   al ) in which the first end portions of the leg portions of the first segment conductor protrude axially outward from the first end surface of the first stator core, and a first close-side coil end portion (first close-side coil end portion  15   a   2 ) in which the curved portion of the first segment conductor protrudes axially outward from the second end surface of the first stator core: 
     the second stator core includes a first end surface (first end surface  24   a ) and a second end surface (second end surface  24   b ) in the axial direction: 
     the second coil includes a plurality of substantially U-shaped second segment conductors (second segment conductors  250 ), and includes second coil end portions (second coil end portion  25   a ) protruding axially outward from the first end surface and the second end surface of the second stator core; 
     the second segment conductor includes a pair of leg portions (leg portions  251 ) extending in parallel with each other and having a first end portion (first end portion  251   a ) and a second end portion (second end portion  251   b ), and a curved portion (curved portion  252 ) connecting the second end portions of the pair of leg portions, and the first end portion of the leg portion is conducted to the first end portion of the leg portion of different second segment conductor; 
     the second coil end portions include a second open-side coil end portion (second open-side coil end portion  25   al ) in which the first end portions of the leg portions of the first segment conductor protrude axially outward from the first end surface of the second stator core, and a second close-side coil end portion (second close-side coil end portion  25   a   2 ) in which the curved portion of the second segment conductor protrudes axially outward from the second end surface of the second stator core: 
     the first rotary electric machine and the second rotary electric machine are arranged such that the first open-side coil end portion and the second open-side coil end portion are on one axial end side (front side) in the axial direction; and the first rotation speed detection device and the second rotation speed detection device are arranged on the one axial end side of the first rotary electric machine and the second rotary electric machine in the axial direction. 
     According to (1), the second rotation axis of the second rotary electric machine is positioned lower than the first rotation axis of the first rotary electric machine, that is, the second rotary electric machine is positioned lower than the first rotary electric machine. Therefore, a part of the refrigerant supplied from the refrigerant supply portion is supplied to the second rotary electric machine through the first rotation speed detection device. Therefore, a part of the refrigerant supplied from the refrigerant supply portion is supplied to the second rotary electric machine. As a result, a cooling efficiency of the second rotary electric machine is improved, thereby improving a cooling efficiency of the rotary electric machine unit. 
     Further, since the refrigerant supplied from the refrigerant supply portion and flowing into the first rotation speed detection device can be supplied to the first open-side coil end portion and the second open-side coil end portion having a larger heat generation amount, the cooling efficiency of the rotary electric machine unit is further improved. In addition, since the refrigerant that has flowed into the second rotation speed detection device can be supplied to the second open-side coil end portion having a larger heat generation amount, the cooling efficiency of the rotary electric machine unit is further improved. 
     (2) The rotary electric machine unit according to (1), where 
     the first rotary electric machine and the second rotary electric machine are arranged so as to partially overlap with each other in the upper-lower direction as viewed from the axial direction. 
     According to (2), since the first rotary electric machine and the second rotary electric machine are arranged so as to partially overlap with in the upper-lower direction, a dimension of the rotary electric machine unit in the upper-lower direction can be reduced, and the rotary electric machine unit can be reduced in a size. 
     (3) The rotary electric machine unit according to (1) or (2), where 
     the second rotary electric machine is arranged such that the second coil end portion overlaps with at least one end portion (left end portion  15   a L) of the first coil end portion of the first rotary electric machine in the left-right direction as viewed from the axial direction. 
     According to (3), the second rotary electric machine is arranged such that the second coil end portion overlaps with at least one end portion of the first coil end portion of the first rotary electric machine in the left-right direction as viewed from the axial direction. Therefore, the refrigerant supplied from the refrigerant supply portion, flowing along the first coil end portion of the first coil and flowing down from the end portion on one side in the left-right direction of the first coil end portion is supplied to the second coil end portion of the second rotary electric machine. As a result, more refrigerant supplied from the refrigerant supply portion can be supplied to the second coil end portion of the second rotary electric machine, so that the cooling efficiency of the rotary electric machine unit is further improved. 
     (4) The rotary electric machine unit according to any one of (1) to (3), where 
     the second rotary electric machine is arranged such that the second rotation axis does not overlap with the first rotary electric machine in the left-right direction as viewed from the axial direction. 
     According to (4), since the second rotary electric machine is arranged such that the second rotation axis does not overlap with the first rotary electric machine in the left-right direction as viewed from the axial direction, the first rotary electric machine does not exist at an upper end portion of the second rotary electric machine. Therefore, a separate refrigerant supply portion can be easily arranged above the upper end portion of the second rotary electric machine. As a result, the refrigerant having a lower temperature from the second refrigerant supply portion that has not passed through the first rotary electric machine can be supplied from the upper end portion of the second rotary electric machine, so that the cooling efficiency of the second rotary electric machine can be further improved and the cooling efficiency of the rotary electric machine unit can be further improved. 
     (5) The rotary electric machine unit according to any one of (1) to (4), where: 
     the first rotary electric machine is an electric motor configured to output power; and 
     the second rotary electric machine is a generator configured to generates power. 
     According to (5), since the first rotary electric machine is an electric motor configured to output power and the second rotary electric machine is a generator configured to generate power, the electric motor required to have a high cooling effect is arranged above, and the generator required to have a low cooling effect than the electric motor is arranged below. Accordingly, the refrigerant having a low temperature supplied from the refrigerant supply portion can be supplied to the first rotary electric machine, which is an electric motor, and the second rotary electric machine, which is a generator, and the second rotary electric machine, which is a generator, has a cooling effect even with the refrigerant after passing through the electric motor, thereby further improving the cooling efficiency of the rotary electric machine unit.