Patent Publication Number: US-2020295627-A1

Title: Rotating electric machine and motor unit

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Priority is claimed on Japanese Patent Application No. 2019-045186, filed on Mar. 12, 2019, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a rotating electric machine and a motor unit. 
     Description of Related Art 
     In a rotating electric machine mounted on a hybrid vehicle, an electric vehicle, or the like, when a current is supplied to a coil, a magnetic field is formed in a stator core and magnetic attraction and repulsion are generated between a rotor (for example, a magnet rotor, a salient pole iron rotor, and a cage rotor) and the stator core. Accordingly, the rotor rotates with respect to the stator. 
     As the stator used in the rotating electric machine, one including a cylindrical stator core which includes a plurality of slots and a coil which includes a coil end portion inserted into the slot and protruding from an axial end surface of the stator core toward the outside in the axial direction is known. For example, in JP 2011-250655 A, a coil is cooled by a refrigerant flowing from a refrigerant passage disposed above a coil end portion toward the coil end portion. A part of a winding constituting the coil includes an end portion which protrudes again outward in the axial direction from an axial end portion of the coil end portion. An end portion of the winding is provided with a groove which guides a refrigerant toward the axial end portion of the coil end portion. 
     SUMMARY OF THE INVENTION 
     However, when the coil is cooled by the refrigerant flowing from the refrigerant passage disposed above the coil end portion toward the coil end portion, there is a possibility that the refrigerant will not readily permeates to the inner peripheral side of the coil end portion depending on a method of winding the coil around the stator core. 
     For that reason, there was room for improvement in distributing the refrigerant evenly to the coil end portion. 
     An aspect of the present invention has been made in view of the above-described circumstances and an object thereof is to provide a rotating electric machine and a motor unit capable of evenly distributing a refrigerant to a coil end portion. 
     In order to solve the above-described problems and achieve the object, the present invention employs the following aspects. 
     (1) A rotating electric machine according to an aspect of the present invention includes: a cylindrical stator core which includes a plurality of slots; a coil which includes a first coil end inserted into the slot and protruding toward one side of the stator core in an axial direction and a second coil end protruding toward the other side in the axial direction; a rotor which is disposed coaxially with the stator core; a shaft which is disposed coaxially with the rotor; and an end wall which is provided at an end side of the shaft and faces the first coil end in the axial direction, wherein the end wall includes a refrigerant outlet which opens in the axial direction so that a refrigerant supplied from the outside is ejected toward the first coil end. 
     (2) In the aspect (1), the first coil end may protrude in a convex bent shape toward one side of the stator core in the axial direction. 
     (3) A motor unit according to an aspect of the present invention includes: two rotating electric machines according to the aspect (1) or (2), the two rotating electric machines being a first rotating electric machine and a second rotating electric machine disposed coaxially with the first rotating electric machine; a contact surface in which the end wall of the first rotating electric machine comes into contact with the end wall of the second rotating electric machine in the axial direction; and a refrigerant supply path which is provided in the contact surface and is connected to the refrigerant outlet so that the refrigerant supplied from the outside can circulate. 
     (4) In the aspect (3), the refrigerant supply path may include a groove which is formed in a surface of the end wall of at least one of the first rotating electric machine and the second rotating electric machine. 
     (5) In the aspect (4), the motor unit may be disposed so that the shaft follows a horizontal direction, the refrigerant outlet may be disposed in an upper portion of the motor unit, and the motor unit may include a refrigerant storage section which has an accommodation space accommodating the first coil end and is able to store the refrigerant ejected from the refrigerant outlet at a lower portion of the motor unit. 
     According to the aspect (1), since the end wall includes the refrigerant outlet which opens in the axial direction so that the refrigerant supplied from the outside is ejected toward the first coil end, the refrigerant is ejected from the refrigerant outlet toward the first coil end in the axial direction. For that reason, the refrigerant easily permeates to the inner peripheral side of the first coil end as compared with a case in which the refrigerant is ejected toward the first coil end from the outside in the radial direction. Thus, it is possible to evenly distribute the refrigerant to the first coil end. 
     Incidentally, when the cylindrical casing accommodating the stator and the rotor is provided, there is a high possibility that the refrigerant does not easily reach the portion of the coil that has entered the inside of the casing in the radial direction. 
     According to this aspect, since the end wall is provided at the end side of the shaft, the refrigerant is easily distributed to the portion having entered the radial inside of the casing in the coil as compared with a case in which the end wall is provided in the middle of the shaft. 
     According to the aspect (2), since the first coil end protrudes in a convex bent shape toward one side of the stator core in the axial direction, the following effects are obtained. Incidentally, in the case of a so-called SC winding (segment conductor coil) in which a U-shaped conductor is inserted into the slot so that one side is a closed segment and the other side is an open segment, the closed-side conductor is more densely arranged than the open-side conductor and hence the refrigerant easily flows down along the outer peripheral surface. According to this aspect, since the refrigerant is ejected toward the first coil end (the closed-side coil end) in the axial direction, this is suitable for evenly distributing the refrigerant to the closed-side coil end. 
     In addition, since a configuration for discharging the refrigerant does not need to be provided on the outside of the first coil end in the radial direction as compared with a case in which the refrigerant is ejected toward the first coil end from the outside in the radial direction, the rotating electric machine can be decreased in size in the radial direction. 
     Additionally, when the second coil end is disposed adjacent to a gear portion, the refrigerant can be ejected from the radial direction toward the second coil end by refrigerant pumping using the gear portion. For this reason, it is sufficient that the refrigerant outlet is disposed only on the side of the first coil end. Accordingly, the refrigerant path can be shortened as compared with a case in which the ejection holes are disposed on both sides of the first coil end and the second coil end and a communication path is provided for the circulation between both ejection holes. 
     According to the aspect (3), since the motor unit includes the contact surface in which the end wall of the first rotating electric machine comes into contact with the end wall of the second rotating electric machine in the axial direction and the refrigerant supply path which is provided in the contact surface and is connected to the refrigerant outlets so that the refrigerant supplied from the outside can circulate, the refrigerant supply path can be shared (unified) between the first rotating electric machine and the second rotating electric machine. For that reason, the refrigerant path can be shortened as compared with a case in which the refrigerant supply path is separately and independently provided in the first rotating electric machine and the second rotating electric machine. Thus, it is possible to evenly distribute the refrigerant to the first coil ends of two rotating electric machines while shortening the refrigerant path. 
     According to the aspect (4), since the refrigerant supply path includes the grooves formed in the surfaces of the end walls of at least one of the first rotating electric machine and the second rotating electric machine, it is easy to form the refrigerant supply path as compared with a case in which the refrigerant supply path is formed only as a through-hole. 
     According to the aspect (5), since the motor unit is disposed so that the shafts follow the horizontal direction and the refrigerant outlets are disposed at the upper portion of the motor unit, the refrigerant ejected from the refrigerant outlets toward the first coil end can flow downward due to its own weight. Additionally, since the motor unit includes the accommodation space which accommodates the first coil end and the refrigerant storage section which can store the refrigerant ejected from the refrigerant outlets at the lower portion of the motor unit, the refrigerant flowing due to the own weight can be stored in the refrigerant storage section. A part (a lower portion) of the first coil end can be immersed by the stored refrigerant. For that reason, it is sufficient that the refrigerant outlets are disposed only at the upper portion of the motor unit. Thus, the refrigerant path can be shortened as compared with a case in which the refrigerant outlets are respectively disposed at the upper portion and the lower portion of the motor unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a motor unit according to a first embodiment. 
         FIG. 2  is a rear view of the motor unit according to the first embodiment. 
         FIG. 3  is a view showing a first rotating electric machine when viewed from the inside of the motor unit in the axial direction in a cross-section of  FIG. 1 . 
         FIG. 4  is a view showing a second rotating electric machine when viewed from the inside of the motor unit in the axial direction including a cross-section IV-IV of  FIG. 1 . 
         FIG. 5  is a cross-sectional view showing the motor unit including a cross-section V-V of  FIG. 3 . 
         FIG. 6  is an enlarged view of a main part of  FIG. 5 . 
         FIG. 7  is a perspective view illustrating a flow of a refrigerant of a motor unit according to a first embodiment. 
         FIG. 8  is a front view illustrating the flow of the refrigerant of the motor unit according to the first embodiment. 
         FIG. 9  is a view illustrating an action of a refrigerant storage section according to the first embodiment including a cross-section IX-IX of  FIG. 2 . 
         FIG. 10  is a cross-sectional view showing a rotating electric machine according to a second embodiment and corresponding to  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments, a motor unit including a rotating electric machine (a traveling motor) mounted on a vehicle such as a hybrid vehicle or an electric vehicle will be described as an example. Hereinafter, a refrigerant supply side to the motor unit from the outside is referred to as a front side and the side opposite to the front side is referred to as a rear side. 
     [First Embodiment] 
     &lt;Motor Unit  100 &gt; 
       FIG. 1  is a front view of a motor unit  100  according to a first embodiment. 
     As shown  FIG. 1 , the motor unit  100  is a twin motor unit including two rotating electric machines  1 A and  1 B. As shown in  FIG. 5 , the two rotating electric machines  1 A and  1 B are the first rotating electric machine  1 A and the second rotating electric machine  1 B disposed coaxially with the first rotating electric machine  1 A. The first rotating electric machine  1 A and the second rotating electric machine  1 B are disposed so as to be independently rotatable. Hereinafter, a direction along an axis C of the rotating electric machine is referred to as an “axial direction”, a direction orthogonal to the axis C is referred to as a “radial direction”, and a direction around the axis C is referred to as a “circumferential direction”. 
     In this embodiment, the motor unit  100  is disposed so that the axis C follows the horizontal direction. In the following description, the components of the first rotating electric machine  1 A may be denoted by “A” at the end of the reference numerals and the components of the second rotating electric machine  1 B may be denoted by “B” at the end of the reference numerals. &lt;First Rotating Electric Machine  1 A&gt; 
     The first rotating electric machine  1 A includes a cylindrical first stator  2 A, a first rotor  3 A disposed coaxially with the first stator  2 A, a first shaft  4 A disposed coaxially with the first rotor  3 A, and a cylindrical first casing  5 A accommodating the first stator  2 A and the first rotor  3 A. 
     &lt;First Stator  2 A&gt; 
     The first stator  2 A includes a first stator core  10 A and a plurality of layers (for example, U-phase, V-phase, and W-phase) of first coils  11 A mounted on the first stator core  10 A. The first stator core  10 A generates a magnetic field by allowing a current to flow in the first coil  11 A. 
     The first stator core  10 A has a cylindrical shape disposed coaxially with the axis C. The first stator core  10 A is fixed to the first casing  5 A. The first stator core  10 A includes a plurality of slots  12  arranged in the circumferential direction. For example, the first stator core  10 A is formed by laminating a plurality of electromagnetic steel sheets (silicon steel sheets) in the axial direction. Additionally, the first stator core  10 A may be a so-called dust core obtained by compression-molding a metal magnetic powder (soft magnetic powder). 
     The first coil  11 A is inserted into the slot  12 . The first coil  11 A has a plurality of conductors arranged in the circumferential direction. The first coil  11 A is a so-called SC winding (segment conductor coil) in which a U-shaped conductor is inserted into the slot  12  so that one side is a closed segment and the other side is an open segment. The first coil  11 A includes an insertion portion  13  which is inserted into the slot  12  of the first stator core  10 A, a first coil end  14  which protrudes toward one side of the first stator core  10 A in the axial direction (the inside of the motor unit  100  in the axial direction), and a second coil end  15  which protrudes toward the other side of the first stator core  10 A in the axial direction (the outside of the motor unit  100  in the axial direction). 
     The first coil end  14  is a closed-side coil end. The first coil end  14  protrudes in a convex bent shape toward one side of the first stator core  10 A in the axial direction. The first coil end  14  includes conductors arranged more densely than the second coil end  15 . 
     The second coil end  15  an open-side coil end. In the second coil end  15 , the conductor end portions are joined to each other and are subjected to coating with a protective paint in order to insulate this joint portion. For example, coating with a protective paint is so-called powder coating in which a powder is adhered to a conductor and then the powder is heated to form a protective film. In this embodiment, the second coil end  15  is subjected to powder coating. Meanwhile, the first coil end  14  is not subjected to powder coating. 
     &lt;First Rotor  3 A&gt; 
     The first rotor  3 A is radially disposed inward with respect to the first stator  2 A with a gap interposed therebetween. The first rotor  3 A is fixed to the first shaft  4 A. The first rotor  3 A is configured to be rotatable around the axis C together with the first shaft  4 A. The first rotor  3 A includes a first rotor core  21 A and a magnet (not shown). For example, the magnet is a permanent magnet. Reference numeral  20  in the drawing denotes an end surface plate disposed at both ends of the first rotor  3 A in the axial direction. 
     The first rotor core  21 A has a cylindrical shape disposed coaxially with the axis 
     C. The first rotor core  21 A is formed by laminating a plurality of electromagnetic steel sheets (silicon steel sheets) in the axial direction. Additionally, the first rotor core  21 A may be a so-called dust core obtained by compression-molding a metal magnetic powder (soft magnetic powder). 
     &lt;First Shaft  4 A&gt; 
     The first shaft  4 A has a hollow structure opening in the axial direction. The axial center portion of the first shaft  4 A is fixed into the first rotor core  21 A in the radial direction by press-inserting and fixing. Both end portions of the first shaft  4 A in the axial direction are supported by a bearing  25  inside the first casing  5 A. 
     &lt;First Casing  5 A&gt; 
     The first casing  5 A includes an end wall  30 A provided at one end portion (end side) of the first shaft  4 A. The end wall  30 A faces the first coil end  14  in the axial direction. The end wall  30 A includes a refrigerant outlet  31 A which opens in the axial direction so that the refrigerant supplied from the outside is ejected toward the first coil end  14 . The refrigerant outlet  31 A is disposed at the upper portion of the motor unit  100 . The refrigerant outlet  31 A is not disposed at the lower portion of the motor unit  100 . Reference numeral  26  in the drawing denotes a cover which is provided in the other end portion of the first shaft  4 A and covers the second coil end  15  from the axial direction. 
     The first casing  5 A includes an accommodation space  32  which accommodates the first coil end  14 . The first casing  5 A includes a refrigerant storage section  33  which can store the refrigerant ejected from the refrigerant outlet  31 A at the lower portion of the motor unit  100  (see  FIG. 9 ). As shown in  FIG. 9 , the refrigerant stored in the refrigerant storage section  33  immerses the first stator  2 A in the lower portion of the motor unit  100 . For example, as the refrigerant, automatic transmission fluid (ATF) or the like which is a hydraulic oil used for lubrication of a transmission, power transmission, or the like is preferably used. 
     &lt;Second Rotating Electric Machine  1 B&gt; 
     As shown in  FIG. 5 , the second rotating electric machine  1 B includes a cylindrical second stator  2 B, a second rotor  3 B disposed coaxially with the second stator  2 B, a second shaft  4 B disposed coaxially with the second rotor  3 B, and a cylindrical second casing  5 B accommodating the second stator  2 B and the second rotor  3 B. In the second rotating electric machine  1 B, the same components as those of the first rotating electric machine  1 A are denoted by the same reference numerals and detailed description thereof will be omitted. 
     The second casing  5 B includes an end wall  30 B provided at one end portion (end side) of the second shaft  4 B. The end wall  30 B comes into contact with the end wall  30 A of the first rotating electric machine  1 A in the axial direction. The end wall  30 B is coupled to the end wall  30 A of the first rotating electric machine  1 A by a fastening member such as a bolt. The end wall  30 B faces the first coil end  14  in the axial direction. The end wall  30 B includes a refrigerant outlet  31 B which opens in the axial direction so that the refrigerant supplied from the outside is ejected toward the first coil end  14 . The refrigerant outlet  31 B communicates with the refrigerant outlet  31 A of the first rotating electric machine  1 A in the axial direction. 
     &lt;Contact Surface  101 &gt; 
     The motor unit  100  includes a contact surface  101  in which the end wall  30 A (hereinafter, referred to as the “first end wall  30 A”) of the first rotating electric machine  1 A comes into contact with the end wall (hereinafter, referred to as the “second end wall  30 B”) of the second rotating electric machine  1 B in the axial direction. The contact surface  101  is a joint surface (a boundary surface) between the first rotating electric machine  1 A and the second rotating electric machine  1 B. The first rotating electric machine  1 A and the second rotating electric machine  1 B has a symmetrical structure in which an imaginary line following the contact surface  101  is a symmetrical axis. That is, the second rotating electric machine  1 B has a shape obtained by mirror-inverting the first rotating electric machine  1 A. 
     &lt;Refrigerant Path  110 &gt; 
     As shown in  FIG. 1 , the refrigerant path  110  is connected to the refrigerant outlets  31 A and  31 B so that the refrigerant supplied from the outside can circulate. The refrigerant path  110  is disposed at the upper portion of the motor unit  100 . The refrigerant path  110  is not disposed at the lower portion of the motor unit  100 . 
     Reference numeral  120  in the drawing denotes a refrigerant introduction pipe which introduces the refrigerant from the outside and reference numeral  130  denotes a refrigerant outlet pipe which leads the refrigerant ejected from the refrigerant outlets  31 A and  31 B to the outside. Hereinafter, an upstream side in the refrigerant flow direction may be simply referred to as an “upstream side” and a downstream side in the refrigerant flow direction may be simply referred to as a “downstream side”. 
     As shown in  FIG. 3 , the refrigerant path  110  includes a first introduction path  111  which introduces the refrigerant introduced from the refrigerant introduction pipe  120  into the contact surface  101 , a refrigerant supply path  113  which is provided in the contact surface  101 , and a second introduction path  112  which introduces the refrigerant introduced from the first introduction path  111  into the refrigerant supply path  113 . 
     The first introduction path  111  is provided in the first casing  5 A. The first introduction path  111  extends in the axial direction from the downstream end of the refrigerant introduction pipe  120  to the contact surface  101  (see  FIG. 8 ). 
     The refrigerant supply path  113  includes a first groove  114 A which is formed in the surface of the first end wall  30 A (the surface facing the second end wall  30 B) and a second groove  114 B which is formed in the surface of the second end wall  30 B (the surface facing the first end wall  30 A) (see  FIG. 6 ). 
     The first groove  114 A has an arc shape that is convex upward. The first groove  114 A is disposed at a position overlapping the first coil end  14  (the closed-side coil end) in the first rotating electric machine  1 A in the axial direction. 
     As shown in  FIG. 4 , the second groove  114 B has an arc shape that is convex upward. The second groove  114 B is disposed at a position overlapping the first groove  114 A in the axial direction (see  FIG. 6 ). The second groove  114 B is disposed at a position overlapping the first coil end  14  (the closed-side coil end) in the second rotating electric machine  1 B in the axial direction. 
     As shown in  FIG. 3 , the second introduction path  112  is provided in the contact surface  101 . The second introduction path  112  is a groove which is provided in the surface of the first end wall  30 A. The second introduction path  112  extends from the downstream end of the first introduction path  111  to the first groove  114 A. The second introduction path  112  is inclined with respect to the horizontal direction so as to be located further downward as it goes toward the first groove  114 A. 
     &lt;Refrigerant Outlets  31 A and  31 B&gt; 
     As shown in  FIG. 6 , the refrigerant outlets  31 A and  31 B include the first ejection hole  31 A connected to the first groove  114 A and the second ejection hole  31 B connected to the second groove  114 B. 
     The first ejection hole  31 A is disposed at a position overlapping the first groove  114 A in the axial direction. A plurality of (for example, nine in the embodiment) first ejection holes  31 A are disposed at the substantially same intervals in the circumferential direction (see  FIG. 3 ). 
     The first ejection hole  31 A includes a first communication portion  115 A which communicates with the first groove  114 A and a first ejection portion  116 A which is disposed coaxially with the first communication portion  115 A. 
     The first communication portion  115 A has a circular cross-section. An outer diameter R 2  of the first communication portion  115 A is smaller than a groove width R 1  of the first groove  114 A (R 2 &lt;R 1 ). An axial length L 2  of the first communication portion  115 A is smaller than a depth L 1  of the first groove  114 A (L 2 &lt;L 1 ). 
     The first ejection portion  116 A has a circular cross-section. An outer diameter R 3  of the first ejection portion  116 A is smaller than the outer diameter R 2  of the first communication portion  115 A (R 3 &lt;R 2 ). An axial length L 3  of the first ejection portion  116 A is longer than the axial length L 2  of the first communication portion  115 A (L 3 &gt;L 2 ). 
     The second ejection hole  31 B is disposed on the side opposite to the first ejection hole  31 A between the first groove  114 A and the second groove  114 B. The second ejection hole  31 B is disposed at a position overlapping the second groove  114 B in the axial direction. A plurality of (for example, nine in the embodiment) second ejection holes  31 B are disposed at the substantially same intervals in the circumferential direction (see  FIG. 4 ). Each of the plurality of second ejection holes  31 B communicates with the first ejection hole  31 A in the axial direction (see  FIG. 8 ). 
     The second ejection hole  31 B includes a second communication portion  115 B which communicates with the second groove  114 B and a second ejection portion  116 B which is disposed coaxially with the second communication portion  115 B. 
     The second communication portion  115 B has a circular cross-section substantially the same size as the first communication portion  115 A. The outer diameter of the second communication portion  115 B is smaller than the groove width of the second groove  114 B. The axial length of the second communication portion  115 B is smaller than the depth of the second groove. 
     The second ejection portion  116 B has a circular cross-section substantially the same size as the first ejection portion  116 A. 
     &lt;Flow of Refrigerant&gt; 
       FIG. 7  is a perspective view illustrating a flow of the refrigerant of the motor unit  100  according to the first embodiment.  FIG. 8  is a front view illustrating a flow of the refrigerant of the motor unit  100  according to the first embodiment.  FIG. 9  is a view illustrating an operation of the refrigerant storage section  33  according to the first embodiment in a cross-section IX-IX of  FIG. 2 . 
     As shown in  FIG. 7 , the refrigerant supplied from the outside is introduced into the refrigerant supply path  113  through the refrigerant introduction pipe  120 , the first introduction path  111 , and the second introduction path  112  (see an arrow V 1  in the drawing). Then, the refrigerant flows in the circumferential direction along the refrigerant supply path  113  (see an arrow V 2  in the drawing). 
     Then, the refrigerant is introduced into the refrigerant outlets  31 A and  31 B and is ejected toward the first coil end  14  (see  FIG. 8 ). As shown in  FIG. 8 , the refrigerant is ejected toward the first coil end  14  (the closed-side coil end) in the first rotating electric machine  1 A through the first ejection hole  31 A (see an arrow V 3  in the drawing) and is ejected toward the first coil end  14  (the closed-side coil end) in the second rotating electric machine  1 B through the second ejection hole  31 B (see an arrow V 4  in the drawing). 
     A part of the refrigerant ejected from the refrigerant outlets  31 A and  31 B is stored in the refrigerant storage section  33  at the lower portion of the motor unit  100  (see  FIG. 9 ). A part of the refrigerant stored in the refrigerant storage section  33  immerses the first stator  2 A and the second stator  2 B at the lower portion of the motor unit  100 . The remaining part of the refrigerant stored in the refrigerant storage section  33  is let out through the refrigerant outlet pipe  130 . Additionally, the downstream end of the refrigerant outlet pipe  130  may be connected to a return flow path (a return path (not shown)) for returning the refrigerant to the refrigerant introduction pipe  120 , another cooling flow path, or the like. 
     As described above, the motor unit  100  of the above-described embodiment includes the cylindrical stator core  10 A ( 10 B) which includes the plurality of slots  12 , the coil  11 A ( 11 B) which includes the first coil end  14  inserted into the slot  12  and protruding toward one side of the stator core  10 A ( 10 B) in the axial direction and the second coil end  15  protruding toward the other side in the axial direction, the rotor  3 A ( 3 B) which is disposed coaxially with the stator core  10 A ( 10 B), the shaft  4 A ( 4 B) which is disposed coaxially with the rotor  3 A ( 3 B), and the end wall  30 A ( 30 B) which is provided at the end side of the shaft  4 A ( 4 B) and faces the first coil end  14  in the axial direction and the end wall  30 A ( 30 B) includes the refrigerant outlet  31 A ( 31 B) which opens in the axial direction so that the refrigerant supplied from the outside is ejected toward the first coil end  14 . 
     According to this configuration, since the end wall  30 A ( 30 B) includes the refrigerant outlet  31 A ( 31 B) which opens in the axial direction so that the refrigerant supplied from the outside is ejected toward the first coil end  14 , the refrigerant is ejected from the refrigerant outlet  31 A ( 30 B) toward the first coil end  14  in the axial direction. For that reason, the refrigerant easily permeates to the inner peripheral side of the first coil end  14  as compared with a case in which the refrigerant is ejected toward the first coil end  14  from the outside in the radial direction. Thus, the refrigerant can be evenly distributed to the first coil end  14 . 
     Incidentally, when the cylindrical casing accommodating the stator and the rotor is provided, there is a high possibility that the refrigerant does not easily reach the portion of the coil that has entered the inside of the casing in the radial direction. 
     According to this configuration, since the end wall  30 A ( 30 B) is provided at the end side of the shaft  4 A ( 4 B), the refrigerant is easily distributed to the portion having entered the inside of the casing  5 A ( 5 B) in the radial direction in the coil  11 A ( 11 B) as compared with a case in which the end wall is provided in the middle of the shaft. 
     In the above-described embodiment, since the first coil end  14  protrudes in a convex bent shape at one axial side of the stator core  10 A ( 10 B), the following effects are obtained. Incidentally, when the coil is the SC winding, the closed-side conductor is more densely arranged than the open-side conductor and hence the refrigerant easily flows down along the outer peripheral surface. According to this configuration, since the refrigerant is ejected toward the first coil end  14  (the closed-side coil end) in the axial direction, this is suitable for evenly distributing the refrigerant to the closed-side coil end. 
     In addition, since a configuration for discharging the refrigerant does not need to be provided on the outside of the first coil end  14  in the radial direction as compared with a case in which the refrigerant is ejected toward the first coil end  14  from the outside in the radial direction, the motor unit  100  can be decreased in size in the radial direction. 
     Additionally, when the second coil end  15  is disposed adjacent to a gear portion, the refrigerant can be ejected from the radial direction toward the second coil end  15  by refrigerant pumping using the gear portion. For this reason, it is sufficient that the refrigerant outlet  31 A ( 31 B) is disposed only on the side of the first coil end  14 . Accordingly, the refrigerant path  110  can be shortened as compared with a case in which the ejection holes are disposed on both sides of the first coil end  14  and the second coil end  15  and a communication path is provided for the circulation between both ejection holes. 
     In the above-described embodiment, the motor unit  100  includes two rotating electric machines  1 A and  1 B. Two rotating electric machines  1 A and  1 B are the first rotating electric machine  1 A and the second rotating electric machine  1 B disposed coaxially with the first rotating electric machine  1 A. The motor unit  100  includes the contact surface  101  in which the end wall  30 A of the first rotating electric machine  1 A comes into contact with the end wall  30 B of the second rotating electric machine  1 B in the axial direction and the refrigerant supply path  113  which is provided in the contact surface  101  and is connected to the refrigerant outlet so that the refrigerant supplied from the outside can circulate. 
     According to this configuration, since the motor unit  100  includes the contact surface  101  in which the end wall of the first rotating electric machine  1 A comes into contact with the end wall of the second rotating electric machine  1 B in the axial direction and the refrigerant supply path  113  which is provided in the contact surface  101  and is connected to the refrigerant outlets  31 A and  31 B so that the refrigerant supplied from the outside can circulate, the refrigerant supply path  113  can be shared (unified) between the first rotating electric machine  1 A and the second rotating electric machine  1 B. For that reason, the refrigerant path  110  can be shortened as compared with a case in which the refrigerant supply path  113  is separately and independently provided in the first rotating electric machine  1 A and the second rotating electric machine  1 B. Thus, it is possible to evenly distribute the refrigerant to the first coil ends  14  of two rotating electric machines  1 A and  1 B while shortening the refrigerant path  110 . 
     In the above-described embodiment, since the refrigerant supply path  113  includes the grooves  114 A and  114 B formed in the surfaces of the end walls  30 A and  30 B of at least one of the first rotating electric machine  1 A and the second rotating electric machine  1 B, it is easy to form the refrigerant supply path  113  as compared with a case in which the refrigerant supply path  113  is formed only as a through-hole. 
     In the above-described embodiment, since the motor unit  100  is disposed so that the shafts  4 A and  4 B follow the horizontal direction and the refrigerant outlets  31 A and  31 B are disposed at the upper portion of the motor unit  100 , the refrigerant ejected from the refrigerant outlets  31 A and  31 B toward the first coil end  14  can flow downward due to its own weight. Additionally, since the motor unit  100  includes the accommodation space  32  which accommodates the first coil end  14  and the refrigerant storage section  33  which can store the refrigerant ejected from the refrigerant outlets  31 A and  31 B at the lower portion of the motor unit  100 , the refrigerant flowing due to the own weight can be stored in the refrigerant storage section  33 . A part (a lower portion) of the first coil end  14  can be immersed by the stored refrigerant. For that reason, it is sufficient that the refrigerant outlets  31 A and  31 B are disposed only at the upper portion of the motor unit  100 . Thus, the refrigerant path  110  can be shortened as compared with a case in which the refrigerant outlets  31 A and  31 B are respectively disposed at the upper portion and the lower portion of the motor unit  100 . 
     [Modified Example of First Embodiment] 
     In the above-described embodiment, a configuration in which the refrigerant supply path  113  includes the first groove  114 A formed in the surface of the first end wall  30 A and the second groove  114 B formed in the surface of the second end wall  30 B has been described, but the present invention is not limited thereto. For example, the refrigerant supply path  113  may be a groove formed only at one of the surface of the first end wall  30 A and the surface of the second end wall  30 B. For example, the refrigerant supply path  113  may be formed by a combination of a groove and a through-hole. For example, the refrigerant supply path  113  may be formed only by a through-hole. 
     In the above-described embodiment, a configuration in which the refrigerant supply path  113  is shared (unified) between the first rotating electric machine  1 A and the second rotating electric machine  1 B has been described, but the present invention is not limited thereto. For example, the refrigerant supply path  113  may be separately and independently provided in the first rotating electric machine  1 A and the second rotating electric machine  1 B. 
     In the above-described embodiment, a configuration in which the refrigerant outlets  31 A and  31 B are disposed only at the upper portion of the motor unit  100  has been described, but the present invention is not limited thereto. For example, the refrigerant outlets  31 A and  31 B may be respectively disposed at the upper portion and the lower portion of the motor unit  100 . 
     In the above-described embodiment, a configuration in which the plurality of refrigerant outlets  31 A and  31 B are arranged at the substantially same intervals in the circumferential direction has been described, but the present invention is not limited thereto. For example, the arrangement intervals of the refrigerant outlets  31 A and  31 B in the circumferential direction need not be the same and may be unequal intervals. 
     In the above-described embodiment, a configuration in which the motor unit  100  is disposed so that the shafts  4 A and  4 B follow the horizontal direction has been described, but the present invention is not limited thereto. For example, the motor unit  100  may be disposed so that the shafts  4 A and  4 B follow the vertical direction. The arrangement of the shafts  4 A and  4 B can be changed to an arbitrary direction in accordance with the design specification. 
     In the above-described embodiment, a configuration in which the coil is the SC winding has been described, but the present invention is not limited thereto. For example, the coil may be a continuous winding or the like other than the SC winding. 
     For example, the coil may have a shape with a straight conductor inserted into the slot and twisted on both sides. For example, the coil may protrude without a bent shape that is convex outward in the axial direction. 
     [Second Embodiment] 
     Hereinafter, a second embodiment of the present invention will be described. In the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals and detailed description thereof will be omitted. 
     In the first embodiment, a configuration in which the motor unit is a twin motor unit including two rotating electric machines has been described, but the present invention is not limited thereto. For example, the motor unit may be a single motor unit including a single rotating electric machine. 
       FIG. 10  is a cross-sectional view showing a rotating electric machine  201  according to the second embodiment and corresponding to  FIG. 5 . 
     As shown in  FIG. 10 , the rotating electric machine  201  includes a cylindrical stator  202 , a rotor  203  disposed coaxially with the stator  202 , a shaft  204  disposed coaxially with the rotor  203 , and a cylindrical casing  205  accommodating the stator  202  and the rotor  203 . 
     The stator  202  includes a cylindrical stator core  210  including a plurality of slots  212  and a coil  211  inserted into the slot  212 . The coil  211  includes an insertion portion  213  which is inserted into the slot  212  of the stator core  210 , a first coil end  214  which protrudes in a convex bent shape toward one side of the stator core  210  in the axial direction, and a second coil end  215  which protrudes toward the other side in the axial direction. 
     The casing  205  includes an end wall  230  which is provided in an end portion of the shaft  204  and faces the first coil end  214  in the axial direction. The end wall  230  includes a refrigerant outlet  231  which opens in the axial direction so that the refrigerant supplied from the outside is ejected toward the first coil end  214 . 
     As described above, the rotating electric machine  201  of the embodiment includes the cylindrical stator core  210  which includes the plurality of slots  212 , the coil  211  which includes the first coil end  214  inserted into the slot  212  and protruding in a convex bent shape toward one side of the stator core  210  in the axial direction and the second coil end  215  protruding toward the other side in the axial direction, the rotor  203  which is disposed coaxially with the stator core  210 , the shaft  204  which is disposed coaxially with the rotor  203 , and the end wall  230  which is provided in the end portion of the shaft  204  and faces the first coil end  214  in the axial direction and the end wall  230  includes the refrigerant outlet  231  which opens in the axial direction so that the refrigerant supplied from the outside is ejected toward the first coil end  214 . 
     According to this configuration, since the end wall  230  includes the refrigerant outlet  231  which opens in the axial direction so that the refrigerant supplied from the outside is ejected toward the first coil end  214 , the refrigerant is ejected from the refrigerant outlet  231  toward the first coil end  214  in the axial direction. For that reason, the refrigerant easily permeates to the inner peripheral side of the first coil end  214  as compared with a case in which the refrigerant is ejected toward the first coil end  214  from the radial outside. Thus, the refrigerant can be evenly distributed to the first coil end  214 . 
     Incidentally, when the coil is the SC winding, the closed-side conductor is more densely arranged than the open-side conductor and hence the refrigerant easily flows down along the outer peripheral surface. According to this configuration, since the refrigerant is ejected toward the first coil end  214  (the closed-side coil end) in the axial direction, this is suitable for evenly distributing the refrigerant to the closed-side coil end. 
     Additionally, since a configuration for discharging the refrigerant does not need to be provided on the radial outside of the first coil end  214  as compared with a case in which the refrigerant is ejected toward the first coil end  214  at the radial outside, the rotating electric machine  201  can be decreased in size in the radial direction. 
     In addition, when the second coil end  215  is disposed adjacent to a gear portion, the refrigerant can be ejected from the radial direction toward the second coil end  215  by refrigerant pumping using the gear portion. For this reason, it is sufficient that the refrigerant outlet  231  is disposed only on the side of the first coil end  214 . Accordingly, the refrigerant path can be shortened as compared with a case in which the ejection holes are disposed on both sides of the first coil end  214  and the second coil end  215  and a communication path is provided for the circulation between both ejection holes. 
     In the above-described embodiment, an example has been described in which the rotating electric machine is a traveling motor mounted on a vehicle such as a hybrid vehicle or an electric vehicle, but the present invention is not limited thereto. For example, the rotating electric machine may be a motor for power generation or other uses or a rotating electric machine (including a generator) other than for a vehicle. 
     Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto and additions, omissions, substitutions, and other modifications of the configuration can be made without departing from the spirit of the invention. Furthermore, the above-described modifications can be appropriately combined.