Patent Publication Number: US-2023134155-A1

Title: Drive apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present invention claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2021-178103 filed on Oct. 29, 2021, the entire content of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a drive apparatus. 
     Background 
     In recent years, the development of drive apparatuses to be mounted on electric vehicles has been actively carried out. Such a drive apparatus is equipped with a cooling structure for cooling a stator of a rotating electrical machine. There is a conventional structure in which oil flowing out from a catch tank is guided by an oil guide portion of a bus bar and drips onto a rotary electric machine. 
     In the motor, since the heat generation amount of the coil is the largest, efficient cooling can be performed by feeding the fluid to the coil end where the coil is exposed. On the other hand, since the bus bar of the conventional structure extends along the axial direction of the motor, when the fluid is guided from the bus bar to the coil end, there is a problem that it is difficult to feed the fluid to the entire coil end and the cooling efficiency is poor. 
     SUMMARY 
     One aspect of an exemplary drive apparatus of the present invention includes: a rotor having a shaft that rotates about a central axis; a stator disposed radially outside the rotor; a bus bar unit having a plurality of bus bars connected to the stator and a bus bar holder supporting the bus bars; a fluid feed portion disposed radially outside the stator and provided with a feed hole for supplying a fluid to the stator; and a housing that accommodates the rotor, the stator, the bus bar unit, and the fluid feed portion. The bus bar unit extends along the circumferential direction along the outer periphery of the stator and has an opening portion that opens toward the stator. 
     The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic cross-sectional view of a drive apparatus according to an embodiment; 
         FIG.  2    is a perspective view of a stator according to an embodiment; 
         FIG.  3    is a schematic view illustrating a circuit of a winding portion according to an embodiment; 
         FIG.  4    is a perspective view of a bus bar unit according to an embodiment; 
         FIG.  5    is a perspective view of a neutral point bus bar and a plurality of phase bus bars according to an embodiment; 
         FIG.  6    is a cross-sectional view of a fluid feed portion, a bus bar unit, and a stator according to an embodiment; 
         FIG.  7    is a schematic cross-sectional view of the vicinity of an opening portion of a bus bar unit according to Modification 1; 
         FIG.  8    is a schematic cross-sectional view of the vicinity of an opening portion of a bus bar unit according to Modification 2; 
         FIG.  9    is a schematic cross-sectional view of the vicinity of an opening portion of a bus bar unit according to Modification 3; 
         FIG.  10    is a schematic cross-sectional view of the vicinity of an opening portion of a bus bar unit of Modification 4; and 
         FIG.  11    is a schematic cross-sectional view of the vicinity of an opening portion of a bus bar unit of Modification 5. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an embodiment of a drive apparatus  1  will be described with reference to the drawings. In the drawings, an XYZ coordinate system is illustrated appropriately as a three-dimensional orthogonal coordinate system. A Z-axis direction appropriately illustrated in each drawing is an up-down direction in which a positive side is an “upper side” and a negative side is a “lower side”. The central axis J appropriately illustrated in each drawing is parallel to the Y-axis direction. In the following description, the axial direction of the central axis J may be simply referred to as “axial direction”, the +Y side may be referred to as “one side in the axial direction”, and the −Y side may be referred to as “the other side in the axial direction”. A radial direction centered on the central axis J is simply referred to as a “radial direction” in some cases. Further, in some cases, the circumferential direction centered on the central axis J is simply referred to as the “circumferential direction”, a counterclockwise direction when viewed from the +Y side is referred to as “one side θ 1  in the circumferential direction”, and a clockwise direction when viewed from the +Y side is referred to as “the other side θ 2  in the circumferential direction”. 
     The up-down direction, the upper side, and the lower side are merely names for describing an arrangement relationship between the respective units, and an actual arrangement relationship and the like may be other than the arrangement relationship indicated by these names. Furthermore, the directions described as one side in the axial direction and the other side in the axial direction can reproduce an effect of the embodiment even when being replaced with each other. Similarly, the directions described as the one side θ 1  in the circumferential direction and the other side θ 2  in the circumferential direction can reproduce the effect of the embodiment even when being replaced with each other. 
       FIG.  1    is a schematic cross-sectional view of a drive apparatus  1  according to the present embodiment. 
     The drive apparatus  1  of the present embodiment is an inner rotor type motor. The drive apparatus  1  of the present embodiment is a three-phase AC motor. The drive apparatus  1  has both a function as a motor and a function as a generator. The center of the drive apparatus  1  is the central axis J. 
     The drive apparatus  1  includes a rotor  3 , a stator  2 , a bus bar unit  5 , a connection bus bar unit  7 , a temperature sensor  8 , a fluid feed portion  95 , a housing  4 , and a fluid O accumulated inside the housing  4 . 
     The housing  4  accommodates the rotor  3 , the stator  2 , the bus bar unit  5 , the connection bus bar unit  7 , and the fluid feed portion  95 . The fluid O is accumulated in a lower region inside the housing  4 . A flow path  9  is connected to the housing  4 , and transfers the fluid O to the fluid feed portion  95  disposed in an upper region of the housing  4 . 
     The housing  4  includes a cylindrical portion  4   b  having a bottom plate portion  4   a,  and a bearing holder  4   c  that covers an opening of the cylindrical portion  4   b.  The cylindrical portion  4   b  has a cylindrical shape centered on the central axis J. The cylindrical portion  4   b  surrounds the stator  2  from the radially outer side. The bottom plate portion  4   a  is located on the other side (−Y side) in the axial direction of the stator  2 . On the other hand, the bearing holder  4   c  is located on one side (+Y side) in the axial direction of the stator  2 . The bearing holder  4   c  and the bottom plate portion  4   a  hold the bearing  3   p.    
     The rotor  3  is rotatable about the central axis J. The rotor  3  is disposed radially inward of the stator  2  having an annular shape. That is, the rotor  3  opposes the stator  2  in the radial direction. The rotor  3  includes a shaft  3   a,  a rotor magnet  3   b,  and a rotor core  3   c.    
     The shaft  3   a  extends in the axial direction along the central axis J. The shaft  3   a  has a columnar shape that is centered on the central axis J and extends in the axial direction. The shaft  3   a  rotates about the central axis J. The shaft  3   a  is rotatably supported by two bearings  3   p.    
     The rotor core  3   c  is formed by laminating magnetic steel plates. The rotor core  3   c  has a tubular shape extending in the axial direction. An inner peripheral surface of the rotor core  3   c  is fixed to an outer peripheral surface of the shaft  3   a.  The rotor core  3   c  has a holding hole  3   h  into which the rotor magnet  3   b  is inserted and fixed. 
     The rotor magnet  3   b  faces the stator  2  in the radial direction. The rotor magnet  3   b  is held in a state of being embedded in the rotor core  3   c.  The rotor magnet  3   b  of the present embodiment has eight poles. The number of poles of the rotor  3  is not limited to that in the present embodiment. The rotor magnet  3   b  may be a magnet of another form such as an annular ring magnet. 
     The stator  2  faces the rotor  3  in the radial direction with a gap interposed therebetween. In the present embodiment, the stator  2  is disposed radially outward of the rotor  3 . The stator  2  includes a stator core  20  and a winding portion  30  attached to the stator core  20 . 
       FIG.  2    is a perspective view of the stator  2  of the present embodiment. 
     The stator core  20  has an annular shape centered on the central axis J. The stator core  20  consists of electromagnetic steel sheets stacked along the axial direction. The stator core  20  includes a core back  21  having a cylindrical shape centered on the central axis J and a plurality of teeth  22  extending radially inward from the core back  21 . 
     The plurality of teeth  22  are arranged at regular intervals in the circumferential direction. The winding portion  30  is mounted on the teeth  22 . A slot S is provided between the teeth  22  adjacent to each other in the circumferential direction. A plurality of conductors of the winding portion  30  passes through the slot S. In the slot S, an insulating paper (not illustrated) is interposed between the winding portion  30  and the stator core  20 . 
     The core back  21  includes a plurality of fixing portions  29  protruding radially outward from the outer peripheral surface. The fixing portion  29  is fixed to the inner surface of the housing  4 . That is, the stator  2  is fixed to the housing  4  at the fixing portion  29 . A plurality of the fixing portions  29  are provided at intervals in the circumferential direction. The number of fixing portions  29  is, for example, four. The four fixing portions  29  are disposed at regular intervals over the entire circumference in the circumferential direction. 
     In the present embodiment, the fixing portion  29  extends in the axial direction over the entire length of the stator core  20 . The fixing portion  29  is provided with an insertion hole  29   a  axially penetrating the fixing portion  29 . A bolt (not illustrated) extending in the axial direction passes through the insertion hole  29   a.  The bolt passes through the insertion hole  29   a  and is tightened into a screw hole (not illustrated) provided in the inner surface of the housing  4 . The fixing portion  29  is fixed to the housing  4  by fastening the bolt into the screw hole. 
     The winding portion  30  includes a first coil end  30   e  protruding to one side (+Y side) in the axial direction of the stator core  20  and a second coil end  30   f  protruding to the other side (−Y side) in the axial direction of the stator core  20 . 
       FIG.  3    is a schematic view illustrating a circuit of the winding portion  30  of the present embodiment. 
     The winding portion  30  of the present embodiment includes two U-phase coil portions  60 U, two V-phase coil portions  60 V, and two W-phase coil portions  60 W. In the following description, when the U-phase coil portion  60 U, the V-phase coil portion  60 V, and the W-phase coil portion  60 W are not distinguished, they are simply referred to as a coil portion  60 . 
     The bus bar unit  5  of the present embodiment includes three phase bus bars  11 ,  12 , and  13  and one neutral point bus bar  10 . The three phase bus bars  11 ,  12 , and  13  are classified into a U-phase bus bar  11 , a V-phase bus bar  12 , and a W-phase bus bar  13 . 
     The U-phase coil portion  60 U, the V-phase coil portion  60 V, and the W-phase coil portion  60 W are Y-connected by the neutral point bus bar  10  and the phase bus bars  11 ,  12 , and  13 . In the present embodiment, two Y connections corresponding to the two coil portions  60  of each phase are configured, and the respective Y connections are connected in parallel. That is, the winding portion  30  is configured with the two Y-connections by the bus bar unit  5 . 
     The coil portion  60  has a first end  63  and a second end  64 . The first end  63  and the second end  64  are provided at one end and the other end of the coil portion  60 , respectively. The coil portion  60  is attached to the stator core  20  between the first end  63  and the second end  64  to constitute a coil of each phase. The coil portion  60  is connected to the bus bar unit  5  in the first end  63  and the second end  64 . 
     The second ends  64  of the two U-phase coil portions  60 U, the two V-phase coil portions  60 V, and the two W-phase coil portions  60 W are connected to one neutral point bus bar  10 . As a result, the second ends  64  of the six coil portions  60  have the same potential and form a neutral point. That is, the neutral point bus bar  10  forms the neutral point of the three-phase circuit. 
     The first ends  63  of the two U-phase coil portions  60 U are connected to the U-phase bus bar  11 . The first ends  63  of the two V-phase coil portions  60 V are connected to the V-phase bus bar  12 . The first ends  63  of the two W-phase coil portions  60 W are connected to the W-phase bus bar  13 . Alternating currents having phases shifted from each other by 120° are caused to flow through the phase bus bars  11 ,  12 , and  13 . 
     The coil portion  60  of the present embodiment is configured by coupling flat wires in series. As illustrated in  FIG.  2   , the coil portion  60  is inserted into the plurality of slots S and routed in a wave shape. The coil portion  60  has a portion formed by wave-winding the slot S to one side in the circumferential direction and a portion formed by wave-winding the slot S to the other side in the circumferential direction. The portion wave-wound to one side in the circumferential direction and the portion wave-wound to the other side in the circumferential direction are connected by the connection bus bar unit  7 . 
     As illustrated in  FIG.  2   , the connection bus bar unit  7  is disposed on one side in the axial direction of the first coil end  30   e.  The connection bus bar unit  7  extends along the circumferential direction of the central axis J. The connection bus bar unit  7  is fixed to and supported by the bus bar unit  5 . 
     The connection bus bar unit  7  of the present embodiment includes a plurality of connection bus bars  15  that connect the conductive wires to each other at the radially inner end portion of the coil portion  60 , and a connection bus bar holder  80  that holds the plurality of connection bus bars  15 . 
     The bus bar unit  5  is disposed radially outside the first coil end  30   e.  The bus bar unit  5  is located directly above the first coil end  30   e.  The bus bar unit  5  extends along the circumferential direction of the central axis J. Therefore, the bus bar unit  5  extends in the circumferential direction along the outer periphery of the first coil end  30   e  on the upper side of the first coil end  30   e.  The bus bar unit  5  is disposed on one side in the axial direction of an end surface of the stator core  20  facing one side (+Y side) in the axial direction. 
       FIG.  4    is a perspective view of the bus bar unit  5 .  FIG.  5    is a perspective view of the neutral point bus bar  10  and the plurality of phase bus bars  11 ,  12 , and  13 . 
     As illustrated in  FIG.  4   , the bus bar unit  5  includes a plurality of bus bars  10 ,  11 ,  12 , and  13 , and a bus bar holder  90  that supports the bus bars  10 ,  11 ,  12 , and  13 . The plurality of bus bars  10 ,  11 ,  12 , and  13  are connected to the stator  2  (see  FIG.  1   ). The plurality of bus bars  10 ,  11 ,  12 , and  13  are classified into the neutral point bus bar  10  and the three phase bus bars  11 ,  12 , and  13 . 
     As illustrated in  FIG.  5   , the neutral point bus bar  10  and the phase bus bars  11 ,  12 , and  13  have a plate shape. The neutral point bus bar  10  and the phase bus bars  11 ,  12 , and  13  are formed by press working. The neutral point bus bar  10  and the phase bus bars  11 ,  12 , and  13  extend along the circumferential direction. 
     The neutral point bus bar  10  includes a neutral point bus bar main body  10   a,  a plurality of (six in the present embodiment) neutral point connection portions  10   b,  and a plurality of (two in the present embodiment) sensor attachment portions  10   t.    
     The neutral point bus bar main body  10   a  extends in an arcuate shape centered on the central axis J when viewed from the axial direction. The neutral point bus bar main body  10   a  has the radial direction as the plate thickness direction. 
     The neutral point bus bar main body  10   a  is provided with a rectangular notch  10   g  that opens to the other side (−Y side) in the axial direction. The notch  10   g  extends from an edge on the other side (−Y side) in the axial direction of the neutral point bus bar main body  10   a  toward one side (+Y side) in the axial direction. 
     The neutral point connection portion  10   b  protrudes from the neutral point bus bar main body  10   a  to one side (+Y side) in the axial direction. The plurality of neutral point connection portions  10   b  are disposed on the same circumference centered on the central axis J. The neutral point connection portion  10   b  extends in the axial direction (Y-axis direction) with a uniform width. Shapes of all the neutral point connection portions  10   b  coincide with each other. Each neutral point connection portion  10   b  is connected to the second end  64  (see  FIG.  3   ) extending radially outward from the first coil end  30   e  by a joining means such as welding. 
     The sensor attachment portion  10   t  protrudes from the neutral point connection portion  10   b  to one side (+Y side) in the axial direction. The sensor attachment portion  10   t  is bent and provided so as to be offset radially outward of the central axis J with respect to the neutral point connection portion  10   b.  As will be described later, the temperature sensor  8  is attached to the sensor attachment portion  10   t.    
     The phase bus bars  11 ,  12 , and  13  include phase bus bar main bodies  11   a,    12   a,  and  13   a,  a plurality of (two in the present embodiment) phase connection portions  11   b,    12   b,  and  13   b,  extending portions  11   c,    12   c,  and  13   c,  and external connection terminals  11   d,    12   d,  and  13   d,  respectively. 
     Among the three phase bus bars  11 ,  12 , and  13  of the present embodiment, the U-phase bus bar  11  and the V-phase bus bar  12  have the same shape. As a result, the number of types of components can be reduced to achieve cost reduction. All of the three phase bus bars  11 ,  12 , and  13  may have different shapes. 
     The phase bus bar main bodies  11   a,    12   a,  and  13   a  extend along the circumferential direction. At least a part of each of the three phase bus bar main bodies  11   a,    12   a,  and  13   a  overlaps the neutral point bus bar  10  radially outward or axially. 
     The phase bus bar main body  13   a  of the W-phase bus bar  13  is disposed on the other side (−Y side) in the axial direction of the neutral point bus bar main body  10   a.  The phase bus bar main body  13   a  is located on the opening side of the notch  10   g  of the neutral point bus bar main body  10   a.  That is, the phase bus bar main body  13   a  is disposed so as to cover the opening of the notch  10   g.    
     In the phase bus bars  11 ,  12 , and  13 , the phase connection portions  11   b,    12   b,  and  13   b  protrude to one side (+Y side) in the axial direction from the phase bus bar main bodies  11   a,    12   a,  and  13   a.  The plurality of phase connection portions  11   b,    12   b,  and  13   b  are disposed on the same circumference centered on the central axis J. The phase connection portions  11   b,    12   b,  and  13   b  extend in the axial direction (Y-axis direction) with a uniform width. Shapes of all the phase connection portions  11   b,    12   b,  and  13   b  coincide with each other. The phase connection portions  11   b,    12   b,  and  13   b  have the same shape with the neutral point connection portion  10   b.  Each of the phase connection portions  11   b,    12   b,  and  13   b  is joined with the first end  63  (see  FIG.  3   ) extending radially outward from the first coil end  30   e  by joining means such as welding. 
     The extending portions  11   c,    12   c,  and  13   c  of the phase bus bars  11 ,  12 , and  13  extend from the end portions on the one circumferential direction side θ 1  of the phase bus bar main bodies  11   a,    12   a,  and  12   c  to the one axial side (+Y side). 
     The external connection terminals  11   d,    12   d,  and  13   d  are disposed at the end portions on one side (+Y side) in the axial direction of the extending portions  11   c,    12   c,  and  13   c,  respectively. The external connection terminals lid,  12   d,  and  13   d  extend along a plane orthogonal to the central axis J. External terminals (not illustrated) that apply U-phase, V-phase, and W-phase voltages are connected to the external connection terminals  11   d,    12   d,  and  13   d,  respectively. 
     As illustrated in  FIG.  4   , the bus bar holder  90  embeds a part of the neutral point bus bar  10  and the plurality of phase bus bars  11 ,  12 , and  13 . Thus, the bus bar holder  90  holds the neutral point bus bar  10  and the phase bus bars  11 ,  12 , and  13 . The bus bar holder  90  is made of an insulating resin member. The bus bar holder  90  is molded by insert molding in which the neutral point bus bar  10  and the phase bus bars  11 ,  12 , and  13  are embedded. 
     The bus bar holder  90  includes a holder body portion  91  and a plurality of (three in the present embodiment) props  92 . The bus bar holder  90  is mounted on the core back  21  of the stator core  20 . The bus bar holder  90  is fixed to, for example, the stator core  20 . 
     The prop  92  extends upward from the holder body portion  91 . The plurality of props  92  embed the extending portions  11   c,    12   c,  and  13   c  of the phase bus bars  11 ,  12 , and  13 . Accordingly, the props  92  support the extending portions  11   c,    12   c,  and  13   c.    
     The holder body portion  91  embeds the neutral point bus bar main body  10   a  and the phase bus bar main bodies  11   a,    12   a,  and  13   a.  The holder body portion  91  exposes the sensor attachment portion  10   t,  the neutral point connection portion  10   b,  and the phase connection portions  11   b,    12   b,  and  13   b  from the end surface on one side (+Y side) in the axial direction. That is, the sensor attachment portion  10   t,  the neutral point connection portion  10   b,  and the phase connection portions  11   b,    12   b,  and  13   b  protrude to one side (+Y side) in the axial direction with respect to the holder body portion  91 . 
     The holder body portion  91  is provided with an open portion  91   a  that exposes a part of the neutral point bus bar main body  10   a  in the up-down direction. The open portion  91   a  has a rectangular shape when viewed from above. The notch  10   g  is provided in a portion exposed by the open portion  91   a  of the neutral point bus bar main body  10   a.  The bus bar unit  5  penetrates the inside of the notch  10   g  in the radial direction. Here, a region surrounded by the notch  10   g  and the open portion  91   a  is referred to as a first opening portion (opening portion)  5   h.    
     The holder body portion  91  is provided with a holder notch  91   p  recessed downward from the upper end edge. The holder notch  91   p  of the present embodiment is disposed between the phase connection portion  13   b  and the neutral point connection portion  10   b  in the circumferential direction. That is, the bus bar unit  5  opens in the radial direction inside the holder notch  91   p.  Here, a region inside the holder notch  91   p  is referred to as a second opening portion (opening portion)  5   k.    
     The bus bar unit  5  has two opening portions  5   h  and  5   k  that open radially inward and outward. The opening portions  5   h  and  5   k  include the first opening portion  5   h  and the second opening portion  5   k.  The first opening portion  5   h  and the second opening portion  5   k  are arranged in the circumferential direction of the central axis J. 
     In the present embodiment, a case where the bus bar unit  5  is provided with the two opening portions  5   h  and  5   k  will be described, but the number of opening portions is not limited thereto. At least one opening portion may be provided, and three or more opening portions may be provided. 
     As illustrated in  FIG.  4   , two temperature sensors  8  are attached to the bus bar unit  5 . The temperature sensor  8  is attached to the sensor attachment portion  10   t  of the neutral point bus bar  10 . The temperature sensor  8  has a wire  8   c  extending to a control device (not illustrated). 
     The sensor attachment portion  10   t  of the neutral point bus bar  10  is exposed from the bus bar holder  90 . The temperature sensor  8  is in direct contact with the neutral point bus bar  10  at the sensor attachment portion  10   t,  and measures the temperature of the neutral point bus bar  10 . 
     In the following description, one of the two temperature sensors  8  disposed on one circumferential direction side θ 1  is referred to as a first temperature sensor  8   a,  and the other disposed on the other circumferential direction side is referred to as a second temperature sensor  8   b.  Similarly, in the following description, the sensor attachment portion  10   t  to which the first temperature sensor  8   a  is attached is referred to as a first sensor attachment portion  10   ta,  and the sensor attachment portion  10   t  to which the second temperature sensor  8   b  is attached is referred to as a second sensor attachment portion  10   tb.    
     In the present embodiment, a case where the temperature sensor  8  is attached to the neutral point bus bar  10  will be described. However, the temperature sensor  8  may be attached to any of the phase bus bars  11 ,  12 , and  13 . That is, at least one of the plurality of bus bars  10 ,  11 ,  12 , and  13  only needs to have the sensor attachment portion  10   t.    
     As illustrated in  FIG.  1   , the fluid feed portion  95  has a pipe shape extending along the axial direction of the central axis J. The fluid feed portion  95  is disposed inside the housing  4 . The fluid feed portion  95  is located radially outside the stator  2  and directly above the stator  2 . The fluid O flows from the end portion on the other side (−Y side) in the axial direction toward one side (+Y side) in the axial direction to the fluid feed portion  95 . The flow of the fluid O in the fluid feed portion  95  may be in a direction opposite to the present embodiment. 
     In this specification, “directly above” means that they are disposed so as to overlap each other when viewed from above and the up-down direction. 
     The end portion on the other side (−Y side) in the axial direction of the fluid feed portion  95  is connected to the flow path  9 . The flow path  9  sucks up the fluid O accumulated in the housing  4  and sends the fluid O to the fluid feed portion  95 . A pump and a cooler (not illustrated) are disposed in the path of the flow path  9 . The pump pressure-feeds the fluid O in the flow path  9 . On the other hand, the cooler cools the fluid in the flow path  9 . 
     The fluid feed portion  95  is provided with a plurality of feed holes  96 ,  97 , and  98  for feeding the fluid O to the stator  2 . The plurality of feed holes  96 ,  97 , and  98  are arranged along the axial direction. The plurality of feed holes  96 ,  97 , and  98  are holes penetrating in the thickness direction of the pipe constituting the fluid feed portion  95 . The openings of the feed holes  96 ,  97 , and  98  face the stator  2  side. Among the plurality of feed holes  96 ,  97 , and  98 , some feed holes  96  are disposed directly above the first coil end  30   e,  some other feed holes  97  are disposed directly above the second coil end  30   f,  and the other feed holes  98  are disposed directly above the stator core  20 . 
     The bus bar unit  5  is disposed between the feed hole  96  disposed directly above the first coil end  30   e  and the first coil end  30   e.  The feed hole  96  allows the fluid O of the first coil end  30   e  to pass through the bus bar unit  5 . Therefore, the fluid O fed from the feed hole  96  cools not only the first coil end  30   e  but also the bus bar unit  5 . 
     The feed hole  97  disposed directly above the second coil end  30   f  feeds the fluid O to the second coil end  30   f.  Further, the feed hole  98  disposed directly above the stator core  20  feeds the fluid O to the outer peripheral surface of the stator core  20 . 
       FIG.  6    is a cross-sectional view of the fluid feed portion  95 , the bus bar unit  5 , and the stator  2  of the present embodiment. 
     The fluid feed portion  95  is disposed directly above the bus bar unit  5  at least partially. Two feed holes  96  are provided in a portion of the fluid feed portion  95  located directly above the bus bar unit  5 . In the following description, one of the two feed holes  96  is referred to as a first feed hole  96   a,  and the other is referred to as a second feed hole  96   b.  That is, the feed hole  96  includes the first feed hole  96   a  and the second feed hole  96   b.    
     The first opening portion  5   h  and the second opening portion  5   k  of the bus bar unit  5  are disposed side by side along the circumferential direction. As described above, the first opening portion  5   h  and the second opening portion  5   k  open in the radial direction of the central axis J. That is, the first opening portion  5   h  and the second opening portion  5   k  open toward the stator  2 . In the present embodiment, the bus bar unit  5  is disposed above the stator  2 . Therefore, the first opening portion  5   h  and the second opening portion  5   k  open to the upper side and the lower side. 
     The first opening portion  5   h  is disposed in the opening direction of the first feed hole  96   a.  Therefore, at least a part of the fluid O ejected from the first feed hole  96   a  reaches the first opening portion  5   h.  As described above, since the first opening portion  5   h  opens toward the stator  2 , the fluid O reaching the first opening portion  5   h  is fed to the stator  2 . 
     The first opening portion  5   h  of the present embodiment is disposed directly above the central axis J. Since the outer periphery of the stator  2  extends in an arc shape around the central axis J, the outer periphery has the highest height directly above the central axis J. The fluid O dropped downward from the first opening portion  5   h  is fed to the highest portion of the stator  2  and flows to both sides of the stator  2  in the circumferential direction. 
     The second opening portion  5   k  is disposed in the opening direction of the second feed hole  96   b.  Therefore, at least a part of the fluid O ejected from the second feed hole  96   b  reaches the second opening portion  5   k.  The fluid O that has reached the second opening portion  5   k  is fed to the stator  2 . 
     According to the present embodiment, since the first opening portion  5   h  and the second opening portion  5   k  open to the stator  2  side, the fluid O fed from the fluid feed portion  95  to the stator  2  side can pass therethrough. As a result, not only the stator  2  but also the bus bar unit  5  can be cooled by the fluid O. When the neutral point bus bar  10  and the phase bus bars  11 ,  12 , and  13  of the bus bar unit  5  are heated to a high temperature by heat transferred from the winding portion  30  or Joule heat, the electric resistance value increases. By cooling the bus bar unit  5 , the electric resistance values of the neutral point bus bar  10  and the phase bus bars  11 ,  12 , and  13  can be reduced, and the driving efficiency of the drive apparatus  1  can be enhanced. 
     In the present embodiment, the bus bar unit  5  extends in the circumferential direction along the outer periphery of the stator  2 . Therefore, when the fluid O is ejected from the feed hole  96  in the circumferential direction, the fluid O scattered by the bus bar unit  5  extending in the circumferential direction can be received to cool the bus bar unit  5  as a whole. As a result, the cooling efficiency of the bus bar unit  5  can be enhanced by effectively utilizing the fluid O. 
     According to the present embodiment, since the bus bar unit  5  extends in the circumferential direction, the fluid O fed from the feed hole  96  to the bus bar unit  5  is easily guided to the first opening portion  5   h  or the second opening portion  5   k  along the circumferential direction. The fluid O takes heat from the bus bar unit  5  in the process of being guided in the circumferential direction by the bus bar unit  5 , and can efficiently cool the bus bar unit  5 . 
     According to the present embodiment, since the first opening portion  5   h  and the second opening portion  5   k  are provided in the bus bar unit  5 , the fluid O can be intensively fed immediately below the first opening portion  5   h  and the second opening portion  5   k.  As described above, since the first opening portion  5   h  is disposed directly above the central axis J, the fluid O passing through the first opening portion  5   h  is fed to the highest position of the stator  2  (more specifically, the first coil end  30   e ). The fluid O fed from the first opening portion  5   h  to the stator  2  flows substantially uniformly on both circumferential sides of the first coil end  30   e  to efficiently cool the stator  2  along the circumferential direction. 
     The bus bar unit  5  of the present embodiment includes a connection flow path  6  that connects the first feed hole  96   a  and the first opening portion  5   h.  The connection flow path  6  of the present embodiment is recessed radially inward of the central axis J and vertically downward. The connection flow path  6  of the present embodiment extends in a groove shape along a direction orthogonal to the axial direction of the central axis J on the radially outer surface of the bus bar unit  5 . More specifically, the connection flow path  6  has a groove shape that opens radially outward and extends along the circumferential direction. The connection flow path  6  guides the fluid O ejected from the first feed hole  96   a  to the first opening portion  5   h.    
     The connection flow path  6  has a wall portion  6   a  and a bottom portion  6   b.  The wall portion  6   a  extends upward from the bottom portion  6   b.  The wall portion  6   a  surrounds the bottom portion  6   b.  The wall portion  6   a  is an inner surface of the open portion  91   a  of the bus bar holder  90 . The bottom portion  6   b  faces upward. The bottom portion  6   b  is provided with the first opening portion  5   h.  The bottom portion  6   b  of the present embodiment is a surface of the neutral point bus bar  10  exposed by the open portion  91   a.    
     According to the present embodiment, the bus bar unit  5  includes the connection flow path  6 . Therefore, the bus bar unit  5  receives the fluid O ejected from the first feed hole  96   a  and guides the fluid O to the first opening portion  5   h  in a wide region where the connection flow path  6  is provided. According to the present embodiment, since more fluid O can be guided to the first opening portion  5   h  and the fluid O can be fed to a desired position of the stator  2 , the cooling efficiency of the stator  2  can be enhanced. 
     The connection flow path  6  of the present embodiment extends in a groove shape along a direction orthogonal to the axial direction on the radially outer surface of the bus bar unit  5 . The connection flow path of the present embodiment can cause the fluid O to flow along a direction (circumferential direction in the present embodiment) orthogonal to the axial direction. As a result, the fluid O ejected from the first feed hole  96   a  in the direction orthogonal to the axial direction can be efficiently received by the connection flow path  6 . In the process of guiding the fluid O to the first opening portion  5   h  by the groove-shaped connection flow path  6 , the wall portion  6   a  and the bottom portion  6   b  of the connection flow path  6  can be cooled, and the bus bar unit  5  can be efficiently cooled. 
     The connection flow path  6  of the present embodiment is recessed vertically downward in a recessed shape. Therefore, the connection flow path  6  can store the fluid O. The connection flow path  6  of the present embodiment temporarily stores the fluid O when the feed amount of the fluid O from the first feed hole  96   a  to the connection flow path  6  is larger than the flow rate of the fluid that can be dropped from the first opening portion  5   h.  As a result, even after the feeding of the fluid O from the feed hole  96  is stopped, the fluid O can be continuously fed from the bus bar unit  5  toward the stator  2  for a long time. That is, even after the drive apparatus  1  is stopped, the cooling of the stator  2  for restart can be continued. In addition, by storing the fluid O in the fluid feed portion  95 , the bus bar unit  5  can be cooled by the stored fluid O. 
     The neutral point bus bar  10  is exposed at the bottom portion  6   b  of the connection flow path  6  of the present embodiment. Therefore, the fluid O comes into contact with the neutral point bus bar  10  in the process of flowing through the connection flow path  6 . According to the present embodiment, the neutral point bus bar  10  can be directly cooled by the fluid O. 
     As illustrated in  FIG.  4   , a portion of the wall portion  6   a  surrounding the first opening portion  5   h  is defined as a first side wall  6   p,  a second side wall  6   q,  and a third side wall  6   r.  The first side wall  6   p  is disposed on one side (+Y side) in the axial direction of the first opening portion  5   h.  The second side wall  6   q  is disposed on the other side (−Y side) in the axial direction of the first opening portion  5   h  and faces the first side wall  6   p.  The third side wall  6   r  is disposed on one side in the circumferential direction of the first opening portion  5   h  and connects the first side wall  6   p  and the second side wall  6   q.    
     The first side wall  6   p  is configured by an end surface facing the other side (−Y side) in the axial direction of the prop  92  of the bus bar holder  90 . The extending portion  11   c  of the U-phase bus bar  11  is embedded inside the prop  92 . According to the present embodiment, the U-phase bus bar  11  can be cooled by the fluid O accumulated in the connection flow path  6 . 
     The second side wall  6   q  protrudes radially outward with respect to the outer peripheral surface of the bus bar holder  90 . Two ribs  91   c  are provided on the surface on the other side (−Y side) in the axial direction of the second side wall  6   q.  The rib  91   c  reinforces the second side wall  6   q.    
     As illustrated in  FIG.  6   , the third side wall  6   r  is disposed to face the opening direction of the first feed hole  96   a.  According to the present embodiment, the fluid O ejected from the first feed hole  96   a  is received, and scattering of the fluid O from the connection flow path  6  is suppressed. As a result, more fluid can be guided to the first opening portion  5   h.    
     The bottom portion  6   b  is provided with an inclination portion  6   c  that is inclined vertically downward from the first feed hole  96   a  toward the first opening portion  5   h.  The inclination portion  6   c  faces the third side wall  6   r  in the circumferential direction. The connection flow path  6  is recessed downward in a region surrounded by the wall portion  6   a  (that is, the first side wall  6   p,  the second side wall  6   q,  and the third side wall  6   r  illustrated in  FIG.  4   ) and the inclination portion  6   c,  and stores the fluid O. 
     According to the present embodiment, since the inclination portion  6   c  inclined vertically downward toward the first opening portion  5   h  is provided in the bottom portion  6   b  of the connection flow path  6 , the fluid O accumulated in the connection flow path  6  can be guided to the first opening portion  5   h  side. As a result, it is possible to suppress the fluid O from staying in the connection flow path  6 . 
     As illustrated in  FIG.  6   , when viewed from the axial direction of the central axis J, a straight line connecting the first feed hole  96   a  and the first opening portion  5   h  is defined as a first virtual line VL 1 , and a straight line connecting the second feed hole  96   b  and the second opening portion  5   k  is defined as a second virtual line VL 2 . Since the first feed hole  96   a  ejects the fluid O along the first virtual line VL 1 , the fluid O can be efficiently guided to the first opening portion  5   h.  Similarly, since the second feed hole  96   b  ejects the fluid O along the second virtual line VL 2 , the fluid O can be efficiently guided to the second opening portion  5   k.    
     The first sensor attachment portion  10   ta  and the first temperature sensor  8   a  of the present embodiment are disposed immediately below the fluid feed portion  95 . A second temperature sensor attachment portion  10   tb  and the second temperature sensor  8   b  of the present embodiment are provided at positions different from the first virtual line VL 1  and the second virtual line VL 2  without overlapping the first virtual line VL 1  and the second virtual line VL 2  when viewed from the axial direction. 
     According to the present embodiment, the first temperature sensor  8   a  and the second temperature sensor  8   b  are not disposed in the ejection path of the fluid O ejected from the first feed hole  96   a  and the second feed hole  96   b,  and are not directly cooled by the fluid O. As a result, the temperature sensor  8  can be prevented from measuring the temperature of the fluid O, and the temperature of the bus bar unit  5  can be accurately measured. 
     The first sensor attachment portion  10   ta  and the first temperature sensor  8   a  of the present embodiment are disposed between the first virtual line VL 1  and the second virtual line (VL 2 ) when viewed from the axial direction. The first temperature sensor  8   a  measures the temperature of the bus bar unit  5  between a portion cooled by the fluid O fed from the first feed hole  96   a  and a portion cooled by the fluid O fed from the second feed hole  96   b.  As a result, the first temperature sensor  8   a  can measure the temperature of the bus bar unit  5  reflecting the cooling by the fluid O, and can observe the cooling efficiency by the feeding of the fluid O over time. 
     The first sensor attachment portion  10   ta  and the first temperature sensor  8   a  of the present embodiment are located between the fixing portions  29  adjacent to each other in the circumferential direction when viewed from the axial direction. According to the present embodiment, it is possible to suppress interference between the temperature sensor  8  and the fixing portion  29  at the time of the assembly process of the drive apparatus  1 , and to provide the drive apparatus  1  with high reliability. 
     Next, a configuration of an opening portion according to a modification that can be employed in the above-described embodiment will be described. The opening portion of each modification can be adopted instead of the first opening portion  5   h  or the second opening portion  5   k  of the above-described embodiment. 
     Note that, in the description of each modification described below, the same reference numerals are given to the same components as those of the embodiment and the modification described above, and the description thereof will be omitted. 
       FIG.  7    is a schematic cross-sectional view of the vicinity of an opening portion  105   h  of a bus bar unit  105  of Modification 1. 
     The bus bar unit  105  of the present modification includes a bus bar  110  and a bus bar holder  190  in which the bus bar  110  is embedded. The bus bar  110  has a first through hole  110   a,  and the bus bar holder  190  has a second through hole  190   a.  The first through hole  110   a  and the second through hole  190   a  overlap each other when viewed from the thickness direction of the bus bar unit  105 . 
     The first through hole  110   a  and the second through hole  190   a  constitute the opening portion  105   h.  That is, the bus bar unit  105  has the opening portion  105   h.  The opening portion  105   h  of the present modification is provided in a portion where the bus bar  110  and the bus bar holder  190  overlap. Therefore, the bus bar  110  and the bus bar holder  190  are exposed on the inner surface of the opening portion  105   h.  According to the present modification, the bus bar  110  and the bus bar holder  190  can be directly cooled by the fluid O passing through the opening portion  105   h.    
     The bus bar holder  190  includes a connection flow path  106  that connects the feed hole  96  (see  FIG.  6   ) and the opening portion  105   h.  Since the connection flow path  106  is recessed vertically downward, the fluid O can be stored. The connection flow path  106  has a bottom portion  106   b  and a wall portion  106   a.  The bottom portion  106   b  is provided with the opening portion  105   h.  The wall portion  106   a  surrounds the opening portion  105   h.    
     The bottom portion  106   b  and the wall portion  106   a  are a part of the surface of the bus bar holder  190 . The wall portion  106   a  protrudes from an outer peripheral surface  190   f  of the bus bar holder  190 . According to the present modification, the shape, height, and the like of the wall portion  106   a  can be configured relatively freely. 
       FIG.  8    is a schematic cross-sectional view of the vicinity of an opening portion  205   h  of a bus bar unit  205  of Modification 2. 
     The bus bar unit  205  of the present modification includes a bus bar  210  and a bus bar holder  290  in which the bus bar  210  is embedded. The bus bar  210  has a first through hole  210   a,  and the bus bar holder  290  has a second through hole  290   a.  The first through hole  210   a  and the second through hole  290   a  overlap each other when viewed from the thickness direction of the bus bar unit  205 . 
     The first through hole  210   a  and the second through hole  290   a  constitute an opening portion  205   h.  That is, the bus bar unit  205  has the opening portion  205   h.  The opening portion  205   h  of the present modification is provided in a portion where the bus bar  210  and the bus bar holder  290  overlap. Therefore, the bus bar  210  and the bus bar holder  290  are exposed on the inner surface of the opening portion  205   h.  According to the present modification, the bus bar  210  and the bus bar holder  290  can be directly cooled by the fluid O passing through the opening portion  205   h.    
     The bus bar holder  290  includes a connection flow path  206  that connects the feed hole  96  (see  FIG.  6   ) and the opening portion  205   h.  Since the connection flow path  206  is recessed vertically downward, the fluid O can be stored. The connection flow path  206  has a bottom portion  206   b  and a wall portion  206   a.  The bottom portion  206   b  is provided with the opening portion  205   h.  The wall portion  206   a  surrounds the opening portion  205   h.    
     The bottom portion  206   b  and the wall portion  206   a  are a part of the surface of the bus bar holder  290 . The wall portion  206   a  is an inner surface of a recess  290   j  recessed downward with respect to the outer peripheral surface  290   f  of the bus bar holder  290 . According to the present embodiment, since the wall portion  206   a  does not protrude from the outer peripheral surface  290   f  of the bus bar unit  205 , it is easy to reduce the thickness of the bus bar unit  205 . 
       FIG.  9    is a schematic cross-sectional view of the vicinity of an opening portion  305   h  of a bus bar unit  305  of Modification 3. 
     The bus bar unit  305  of the present modification includes a bus bar  310  and a bus bar holder  390  in which the bus bar  310  is embedded. The bus bar  310  has a first through hole  310   a,  and the bus bar holder  390  has a second through hole  390   a.    
     The bus bar  310  of the present modification protrudes inward from the inner surface of the second through hole  390   a  of the bus bar holder  390 . The first through hole  310   a  and the second through hole  390   a  overlap each other when viewed from the thickness direction of the bus bar unit  305 . Therefore, the first through hole  310   a  is included inside the second through hole  390   a  when viewed from the thickness direction of the bus bar unit  305 . 
     The first through hole  310   a  constitutes the opening portion  305   h.  That is, the bus bar unit  305  has the opening portion  305   h.  The opening portion  305   h  of the present modification is provided in a portion where the bus bar holder  390  is not disposed but the bus bar  310  is disposed. Therefore, only the bus bar  310  is exposed on the inner surface of the opening portion  305   h.  According to the present modification, the fluid O passing through the opening portion  305   h  effectively cools the bus bar  310 . 
     The bus bar holder  390  includes a connection flow path  306  that connects the feed hole  96  (see  FIG.  6   ) and the opening portion  305   h.  Since the connection flow path  306  is recessed vertically downward, the fluid O can be stored. The connection flow path  306  has a bottom portion  306   b  and a wall portion  306   a.  The bottom portion  306   b  is provided with the opening portion  305   h.  The wall portion  306   a  surrounds the opening portion  305   h.    
     The bottom portion  306   b  of the present modification is a part of the surface of the bus bar  310 . On the other hand, the wall portion  306   a  of the present modification is a part of the surface of the bus bar holder  390  and is an inner surface of the second through hole  390   a.  According to the present modification, the bus bar  310  can be directly cooled by the fluid O accumulated in the connection flow path  306 . 
       FIG.  10    is a schematic cross-sectional view of the vicinity of an opening portion  405   h  of a bus bar unit  405  of Modification 4. 
     The bus bar unit  405  of the present modification includes a bus bar  410  and a bus bar holder  490  in which the bus bar  410  is embedded. The bus bar  410  protrudes from the outer edge of the bus bar holder  490  and is exposed. The bus bar  410  has the opening portion  405   h  in a portion exposed from the bus bar holder  490 . That is, the bus bar unit  405  has the opening portion  405   h.    
     The opening portion  405   h  of the present modification is provided in a portion where the bus bar holder  490  is not disposed but the bus bar  410  is disposed. Therefore, only the bus bar  410  is exposed on the inner surface of the opening portion  405   h.  According to the present modification, the fluid O passing through the opening portion  405   h  effectively cools the bus bar  410 . 
       FIG.  11    is a schematic cross-sectional view of the vicinity of an opening portion  505   h  of a bus bar unit  505  of Modification 5. 
     The bus bar unit  505  of the present modification includes a bus bar  510  and a bus bar holder  590  in which the bus bar  510  is embedded. The bus bar holder  590  has the opening portion  505   h  in a portion protruding with respect to the outer edge of the bus bar  510 . That is, the bus bar unit  505  has the opening portion  505   h.    
     The opening portion  505   h  of the present modification is provided in a portion where the bus bar  510  is not disposed but the bus bar holder  590  is disposed. Therefore, only the bus bar holder  590  is exposed on the inner surface of the opening portion  505   h.  According to the present modification, since the opening portion  505   h  is configured by the bus bar holder  590 , the shape of the opening portion  505   h  can be configured relatively freely. 
     Although the embodiment of the present invention and the modification thereof have been described above, the respective configurations and combinations thereof in the embodiment and the modification are merely examples, and therefore addition, omission, substation and other variations of the configurations can be made within the scope not departing from the gist of the present invention. Also note that the present invention is not limited by the embodiment. 
     For example, in the above-described embodiment, the case where the fluid feed portion has a pipe shape has been described. However, the fluid feed portion only needs to be configured to be able to feed the fluid toward the stator, and may be, for example, a gutter provided with a feed hole at the bottom portion. 
     Features of the above-described preferred embodiments and the modifications thereof may be combined appropriately as long as no conflict arises. 
     While preferred embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.