Patent Publication Number: US-2023135939-A1

Title: Busbar unit

Description:
TECHNICAL FIELD 
     The present disclosure relates to a busbar unit. 
     BACKGROUND 
     Some of rotating electric machines are provided with a stator including a stator coil and a busbar unit including a busbar to be electrically connected to the stator coil to supply power to the stator coil. In such a rotating electric machine, the stator coil generates heat by energization to the stator coil. If a temperature of the stator coil rises, there is a possibility of failure in each component of the rotating electric machine. Thus, the busbar unit may include a temperature sensor for detecting a temperature of the busbar electrically connected to the stator coil to monitor the temperature of the stator coil. 
     In a busbar unit described in Patent Document 1, one busbar has a U-shaped portion bent into a U shape. A temperature sensor includes a body portion accommodating a thermistor element and arranged between a pair of legs of the U-shaped portion, and an arm portion extending from the body portion to embrace the respective legs of the U-shaped portion. The temperature sensor is attachable to and detachable from the U-shaped portion by resiliently deforming the arm portion. 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         Patent Document 1: JP 2018-061389 A 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved 
     However, if the temperature sensor is attachable to and detachable from the busbar as described in Patent Document 1, it is difficult to hold the body portion accommodating the thermistor element for detecting the temperature of the busbar in close contact with the busbar. Thus, it might become difficult to accurately detect the temperature of the busbar by the temperature sensor. 
     The present disclosure aims to provide a busbar unit capable of improving accuracy in detecting a temperature of a busbar by a temperature sensor. 
     Means to Solve the Problem 
     The present disclosure is directed to a busbar unit to be electrically connected to a stator coil of a stator, the busbar unit including a busbar, a temperature sensor for detecting a temperature of the busbar, and a covering member made of insulating resin for covering the busbar and the temperature sensor, wherein the temperature sensor includes a thermistor element and a case for accommodating the thermistor element, the busbar includes a sensor holding portion for holding the temperature sensor, the sensor holding portion includes a first supporting portion having a first contact surface configured to contact the case, a second supporting portion having a second contact surface facing the first contact surface and configured to contact the case and a coupling portion coupling one end parts of the first and second supporting portions and holds the temperature sensor by sandwiching the case by the first and second contact surfaces, and the covering member covers outsides of the sensor holding portion and the case. 
     Effect of the Invention 
     According to the busbar unit of the present disclosure, it is possible to improve accuracy in detecting the temperature of the busbar by the temperature sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of a busbar unit in one embodiment. 
         FIG.  2    is an exploded perspective view of a busbar and a temperature sensor in the one embodiment. 
         FIG.  3    is a side view of a sensor holding portion and the temperature sensor in the one embodiment. 
         FIG.  4    is a section showing a part of the busbar unit in the one embodiment. 
         FIG.  5    is a perspective view showing a part of the busbar unit in the one embodiment. 
     
    
    
     DETAILED DESCRIPTION TO EXECUTE THE INVENTION 
     Description of Embodiments of Present Disclosure 
     First, embodiments of the present disclosure are listed and described. 
     (1) The busbar unit of the present disclosure is to be electrically connected to a stator coil of a stator and is provided with a busbar, a temperature sensor for detecting a temperature of the busbar, and a covering member made of insulating resin for covering the busbar and the temperature sensor, wherein the temperature sensor includes a thermistor element and a case for accommodating the thermistor element, the busbar includes a sensor holding portion for holding the temperature sensor, the sensor holding portion includes a first supporting portion having a first contact surface configured to contact the case, a second supporting portion having a second contact surface facing the first contact surface and configured to contact the case and a coupling portion coupling one end parts of the first and second supporting portions and holds the temperature sensor by sandwiching the case by the first and second contact surfaces, and the covering member covers outsides of the sensor holding portion and the case. 
     According to the above aspect, the sensor holding portion sandwiches the case by the first and second contact surfaces. Thus, the first and second contact surface in contact with the case are easily held in close contact with the case on both sides in a sandwiching direction of sandwiching the case by the first and second contact surfaces. Therefore, the temperature of the busbar is easily transferred to the thermistor element via the case. As a result, accuracy in detecting the temperature of the busbar by the temperature sensor can be improved. 
     (2) Preferably, the case has an abutting surface configured to abut on the sensor holding portion, and the abutting surface is facing the sensor holding portion in a direction orthogonal to the sandwiching direction of sandwiching the case by the first and second contact surfaces. 
     According to the above aspect, the temperature sensor is positioned in the direction orthogonal to the sandwiching direction with respect to the sensor holding portion by the abutment of the abutting surface on the sensor holding portion. 
     (3) Preferably, at least a part of the case and the sensor holding portion are respectively integrated with the covering member while being covered by the covering member, the covering member includes a first exposing hole for exposing a part of a surface of the first supporting portion on a side opposite to the first contact surface to outside and a second exposing hole for exposing a part of a surface of the second supporting portion on a side opposite to the second contact surface to outside, and the first and second exposing holes extend in the sandwiching direction of sandwiching the case by the first and second contact surfaces. 
     According to the above aspect, a pin for forming the first exposing hole and a pin for forming the second exposing hole are provided in a mold for forming the covering member. The pin for forming the first exposing hole extends along the sandwiching direction and abuts on the surface of the first supporting portion on the side opposite to the first contact surface inside the mold. The pin for forming the second exposing hole extends along the sandwiching direction and abuts on the surface of the second supporting portion on the side opposite to the second contact surface inside the mold. Accordingly, the covering member is formed in a state where the sensor holding portion is sandwiched from the both sides in the sandwiching direction by these pins. Thus, the separation of the first and second supporting portions can be suppressed by these pins when a molten resin material for forming the covering member is filled into the mold. Therefore, it can be suppressed that close contact between the case and the sensor holding portion is reduced when the covering member is formed. 
     (4) Preferably, the case includes a retaining protrusion projecting outwardly of the case from an outer surface of the case, and the retaining protrusion is integrated with the covering member while being covered by the covering member. 
     According to the above aspect, since the retaining protrusion is fit in the covering member, a relative movement of the retaining protrusion with respect to the covering member is suppressed. Therefore, the detachment of the temperature sensor from the busbar can be suppressed not only by sandwiching the case by the sensor holding portion, but also by physically fitting the retaining protrusion and the covering member. 
     (5) Preferably, the case has an abutting surface configured to abut on the sensor holding portion on one end part and the retaining protrusion on the other end part, out of both end parts in the sandwiching direction of the case, the abutting surface is facing the sensor holding portion in a direction orthogonal to the sandwiching direction, the retaining protrusion has a facing surface facing the sensor holding portion, a facing direction of the facing surface and the sensor holding portion is the same as a facing direction of the abutting surface and the sensor holding portion, and positions of the abutting surface and the facing surface are shifted in the facing direction. 
     According to the above aspect, since the positions of the abutting surface and the facing surface are shifted in the facing direction, it can be suppressed that the temperature sensor is attached to the sensor holding portion in an improper posture inverted from a proper attachment posture with respect to the sensor holding portion when the case is attached to the sensor holding portion. 
     Details of Embodiments of Present Disclosure 
     A specific example of a busbar unit of the present disclosure is described below with reference to the drawings. Note that the present invention is not limited to these illustrations and is intended to be represented by claims and include all changes in the scope of claims and in the meaning and scope of equivalents. 
     One embodiment of the busbar unit is described below. Note that constituent elements may be enlargedly shown to facilitate understanding in the accompanying drawings. Further, dimensional ratios of the constituent elements may be different from actual ones or those in other figures. 
     A busbar unit  10  of this embodiment shown in  FIG.  1    is provided in a rotating electric machine used, for example, in a motor generator or the like of a hybrid or electric vehicle. The rotating electric machine includes an unillustrated annular stator core. An unillustrated stator coil is wound on this stator core. The busbar unit  10  is arranged on one end part in an axial direction of the stator core. 
     (Configuration of Busbar Unit  10 ) 
     The busbar unit  10  includes a busbar  13  to be electrically connected to the stator coil and a temperature sensor  14  for detecting a temperature of the busbar  13 . 
     (Configuration of Busbar  13 ) 
     In this embodiment, the busbar  13  serves as a neutral point of the stator coil. The end part of the stator coil is electrically connected to the busbar  13  by welding or the like. In this way, the busbar unit  10  is electrically connected to the stator coil. 
     The busbar  13  is formed of an electrically conductive metal plate material. Copper or copper alloy excellent in electrical conductivity can be, for example, used as a material of the busbar  13 . 
     The busbar  13  has a substantially arcuate shape as a whole. The busbar  13  includes a strip-like busbar body  21  and a sensor holding portion  22  integrally provided on one end in a longitudinal direction of the busbar body  21 . That is, the busbar  13  includes the sensor holding portion  22  on one end part in the longitudinal direction. 
     The busbar body  21  is in the form of a strip arcuately extending when viewed from a plate thickness direction of the busbar body  21 . Note that the busbar body  21  may not have a fixed width in a transverse direction or may have a stepped shape. Incidentally, the longitudinal direction of the busbar body  21  is shown as a direction of an arrow C, the transverse direction of the busbar body  21  is shown as a direction of an arrow R and the plate thickness direction of the busbar body  21  is shown as a direction of an arrow A. 
     As shown in  FIGS.  2  and  3   , the sensor holding portion  22  is formed by bending a part of the busbar  13  into a U shape. The sensor holding portion  22  includes a pair of first and second supporting portions  31 ,  32  and a coupling portion  33  coupling one end parts of the first and second supporting portions  31 ,  32 . 
     The first and second supporting portions  31 ,  32  are in the form of rectangular flat plates. The second supporting portion  32  extends in the longitudinal direction from one end in the longitudinal direction of the busbar body  21 . A plate thickness direction of the second supporting portion  32  is along that of the busbar body  21 . The first supporting portion  31  is separated from the second supporting portion  32  in the plate thickness direction of the second supporting portion  32 . Further, the first supporting portion  31  is facing the second supporting portion  32  in the plate thickness direction of the second supporting portion  32 . A plate thickness direction of the first supporting portion  31  is along that of the second supporting portion  32 . Further, the first supporting portion  31  extends along the transverse direction of the busbar body  21  when viewed from the plate thickness direction of the busbar body  21 . 
     The coupling portion  33  is in the form of a plate extending along the plate thickness direction of the busbar body  21 , i.e. the plate thickness direction of the second supporting portion  32 . Further, a plate thickness direction of the coupling portion  33  is along the transverse direction of the busbar body  21 . The coupling portion  33  couples the one end part of the first supporting portion  31  in the transverse direction of the busbar body  21  and the one end part of the second supporting portion  32  in the transverse direction of the busbar body  21 . Thus, the sensor holding portion  22  of this embodiment has a U shape open on one side in the transverse direction of the busbar body  21  when viewed from the longitudinal direction of the busbar body  21 . 
     The first supporting portion  31  has a first contact surface  31   a . The first contact surface  31   a  is a side surface of the first supporting portion  31  facing the second supporting portion  32 . Further, the second supporting portion  32  has a second contact surface  32   a . The second contact surface  32   a  is a side surface of the second supporting portion  32  facing the first supporting portion  31  and a surface facing the first contact surface  31   a  in the plate thickness direction of the second supporting portion  32 . 
     The sensor holding portion  22  is resiliently deformable to change an interval between the first and second supporting portions  31 ,  32  in the plate thickness direction of the second supporting portion  32 , i.e. to change a distance between the first and second contact surfaces  31   a ,  32   a  in the plate thickness direction of the second supporting portion  32 . 
     (Configuration of Temperature Sensor  14 ) 
     As shown in  FIGS.  2  and  4   , the temperature sensor  14  includes a thermistor element  41  and a case  51  for accommodating the thermistor element  41 . One end parts of a pair of wires  42  are electrically connected to the thermistor element  41 , and a connector portion  43  is provided on the other end parts of the wires  42 . The connector portion  43  is shown only in  FIG.  1   . 
     The case  51  is made of an insulating resin material, e.g. polyphenylene sulfide resin (PPS). The resin material of the case  51  may contain additives such as a filler. The case  51  has a rectangular parallelepiped shape. Here, one outer side surface constituting an outer peripheral surface extending in a longitudinal direction of the case  51  is a first outer side surface  52   a . In  FIGS.  2  and  4   , the first outer side surface  52   a  corresponds to the upper surface of the case  51 . Further, out of outer side surfaces constituting the outer peripheral surface extending in the longitudinal direction of the case  51 , an outer side surface located on the back of the first outer side surface  52   a  is a second outer side surface  52   b . Note that the second outer side surface  52   b  corresponds to an outer surface of the case  51 . In this embodiment, the second outer side surface  52   b  is parallel to the first outer side surface  52   a . Further, one end in the longitudinal direction of the case  51  is a first end  53   a  and the other end in the longitudinal direction of the case  51  is a second end  53   b.    
     The case  51  includes an element accommodating portion  54  recessed along the longitudinal direction of the case  51  from the second end  53   b  toward the first end  53   a . The thermistor element  41  is arranged in the element accommodating portion  54 . The pair of wires  42  are pulled out to the outside of the case  51  from an opening of the element accommodating portion  54 . The thermistor element  41  is sealed inside the case  51  by a sealing resin  61  filled into the element accommodating portion  54 . The sealing resin  61  is made of an insulating resin material, which may contain additives such as a filler. 
     A step portion  55  is provided on an end part of the first outer side surface  52   a  on the side of the first end  53   a . That is, the step portion  55  is provided on an end part of the first outer side surface  52   a  on a bottom side of the element accommodating portion  54 . The step portion  55  is formed to thin the case  51  in a direction perpendicular to the first outer side surface  52   a . By including this step portion  55 , the case  51  has an abutting surface  56  in the form of a flat surface perpendicular to the first outer side surface  52   a . Note that a part of the case  51  formed with the step portion  55  and closer to the first end  53   a  than the abutting surface  56  serves as an inserting portion  57  to be inserted into the sensor holding portion  22 . 
     As shown in  FIG.  3   , a thickness T 1  of the inserting portion  57  in the direction perpendicular to the first outer side surface  52   a  is larger than the distance between the first and second supporting portions  31 ,  32 , i.e. a distance D 1  between the first and second contact surfaces  31   a ,  32   a , in a state before the temperature sensor  14  is attached to the sensor holding portion  22 . Note that the sensor holding portion  22  and the temperature sensor  14  shown in  FIG.  3    are shown in a side view when the sensor holding portion  22  and the temperature sensor  14  are viewed from a direction of an arrow β in  FIG.  2   . 
     As shown in  FIGS.  2  and  4   , the case  51  includes a retaining protrusion  58  projecting outwardly of the case  51  from the second outer side surface  52   b . The retaining protrusion  58  is in the form of a ridge extending along the transverse direction of the case  51  on the second outer side surface  52   b  when viewed from a direction perpendicular to the second outer side surface  52   b . Further, the retaining protrusion  58  has a rectangular shape projecting from the second outer side surface  52   b  in a cross-section perpendicular to the second outer side surface  52   b  and parallel to the longitudinal direction of the case  51 . 
     Out of both side surfaces of the retaining protrusion  58  in the longitudinal direction of the case  51 , the side surface on the side of the first end  53   a  is a facing surface  59 . The facing surface  59  is facing in the same direction as the abutting surface  56 . The facing surface  59  is provided in parallel to the abutting surface  56  and perpendicular to the second outer side surface  52   b . The positions of the abutting surface  56  and the facing surface  59  are shifted in the longitudinal direction of the case  51 . In this embodiment, the facing surface  59  is located closer to the second end  53   b  than the abutting surface  56  in the longitudinal direction of the case  51 . 
     As shown in  FIGS.  2 ,  4  and  5   , the temperature sensor  14  is held in the sensor holding portion  22 . The temperature sensor  14  is attached to the busbar  13  by inserting the inserting portion  57  into between the first and second supporting portions  31 ,  32  along an extending direction of the busbar body  21 , i.e. the longitudinal direction of the busbar body  21 . Further, the inserting portion  57  of the temperature sensor  14  is inserted into between the first and second supporting portions  31 ,  32  by relatively moving the case  51  with respect to the sensor holding portion  22  along the longitudinal direction of the case  51 . An inserting direction of the temperature sensor  14  into the sensor holding portion  22 , i.e. an inserting direction of the case  51 , is shown by an arrow α in  FIG.  2   . At this time, since the thickness T 1  of the inserting portion  57  is larger than the distance D 1  between the first and second contact surfaces  31   a ,  32   a  in the sensor holding portion  22  before the case  51  is inserted, the inserting portion  57  is press-fit between the first and second supporting portions  31 ,  32 . Accordingly, the first contact surface  31   a  is pressed into contact with the surface of the inserting portion  57  and the second contact surface  32   a  is pressed into contact with the surface of the inserting portion  57 . Then, the inserting portion  57 , i.e. the case  51 , is sandwiched by the first and second supporting portions  31 ,  32 . That is, the sensor holding portion  22  holds the temperature sensor  14  by sandwiching the case  51  by the first and second contact surfaces  31   a ,  32   a . Note that the temperature sensor  14  is inserted into the sensor holding portion  22  along a circumferential direction of the busbar body  21  until the abutting surface  56  abuts on the first supporting portion  31 . By the abutment of the abutting surface  56  on the first supporting portion  31 , the case  51  is positioned in the inserting direction with respect to the sensor holding portion  22 . 
     As shown in  FIGS.  4  and  5   , with the temperature sensor  14  held in the sensor holding portion  22 , the abutting surface  56  is facing and abutting on the sensor holding portion  22  in a direction orthogonal to a sandwiching direction X 1  of sandwiching the case  51  by the first and second contact surfaces  31   a ,  32   a . In this embodiment, the direction orthogonal to the sandwiching direction X 1  is the same as the inserting direction of the case  51  into the sensor holding portion  22  and is the longitudinal direction of the busbar body  21 . That is, the abutting surface  56  is facing and abutting on the first supporting portion  31  in the longitudinal direction of the busbar body  21 . 
     Further, in this state, the retaining protrusion  58  is provided on an end part of the case  51  on a side opposite to an end part where the abutting surface  56  is provided, out of both end parts in the sandwiching direction X 1  of the case  51 . That is, the case  51  has the abutting surface  56  on one end part and the retaining protrusion  58  on the other end part, out of the both end parts in the sandwiching direction X 1  of the case  51 . The facing surface  59  of the retaining protrusion  58  is facing the sensor holding portion  22 . A facing direction of the facing surface  59  and the sensor holding portion  22  is the same as a facing direction X 2  of the abutting surface  56  and the sensor holding portion  22 . Further, since the facing direction X 2  coincides with the longitudinal direction of the case  51  in this embodiment, the positions of the abutting surface  56  and the facing surface  59  are shifted in the facing direction X 2 . Since the facing direction X 2  is the longitudinal direction of the busbar body  21  in this embodiment, the facing surface  59  is facing the second supporting portion  32  in the longitudinal direction of the busbar body  21 . Further, in this embodiment, the facing surface  59  abuts on the second supporting portion  32  from the longitudinal direction of the busbar body  21 . 
     As shown in  FIG.  1   , in this embodiment, the longitudinal direction of the case  51  is along the longitudinal direction of the busbar body  21  and perpendicular to the transverse direction of the busbar body  21  when viewed from the plate thickness direction of the busbar body  21 . Note that the longitudinal direction of the case  51  may not necessarily be perpendicular to the transverse direction of the busbar body  21  and can be an arbitrary direction when viewed from the plate thickness direction of the busbar body  21 . 
     (Configuration of Covering Member  71 ) 
     As shown in  FIGS.  4  and  5   , the busbar unit  10  includes a covering member  71  made of insulating resin for covering the outsides of the sensor holding portion  22  and the case  51 . Insulating resins widely include resins excluding electrically conductive resins and are, for example, polyamide-based resins. The insulating resin may contain additives. In this embodiment, a polyamide-based resin containing a filler and the like as additives is used as the resin material for forming the covering member  71 . 
     A part of the case  51  and the sensor holding portion  22  are respectively integrated with the covering member  71  while being covered by the covering member  71 . In particular, the entire sensor holding portion  22  is embedded inside the covering member  71  and arranged inside the covering member  71 . The covering member  71  covers the outer surface of the sensor holding portion  22  by being held in close contact with this outer surface. Further, a part of the case  51  from the first end  53   a  to a predetermined position between the retaining protrusion  58  and the second end  53   b  is embedded inside the covering member  71  and arranged inside the covering member  71 . That is, the covering member  71  covers a range of the case  51  from the first end  53   a  to the predetermined position between the retaining protrusion  58  and the second end  53   b  from outside. The covering member  71  covers the outer surface of this range of the case  51  by being held in close contact with this outer surface. Thus, the covering member  71  covers the outer surface of the retaining protrusion  58  by being held in close contact with the outer surface. The retaining protrusion  58  is integrated with the covering member  71  while the outer surface of the retaining protrusion  58  is covered by the covering member  71 . Note that the second end  53   b  is exposed from the covering member  71 . The busbar  13 , the temperature sensor  14  and the covering member  71  are integrally formed by insert molding. 
     The covering member  71  includes a first exposing hole  72  and a second exposing hole  73  on both sides of the sensor holding portion  22  in the sandwiching direction X 1 . The first exposing hole  72  exposes a part of a surface of the first supporting portion  31  on a side opposite to the first contact surface  31   a  to outside. The second exposing hole  73  exposes a part of a surface of the second supporting portion  32  on a side opposite to the second contact surface  32   a  to outside. The first and second exposing holes  72 ,  73  extend along the sandwiching direction X 1 . 
     The first and second exposing holes  72 ,  73  are holes simultaneously formed in forming the covering member  71  by insert molding. In forming the covering member  71 , the sensor holding portion  22  sandwiching the case  51  is arranged inside an unillustrated mold for forming the covering member  71 . An unillustrated first pin extending along the sandwiching direction X 1  and configured to abut on the surface of the first supporting portion  31  on the side opposite to the first contact surface  31   a  is provided on the inner surface of this mold. Further, an unillustrated second pin extending along the sandwiching direction X 1  and configured to abut on the surface of the second supporting portion  32  on the side opposite to the second contact surface  32   a  is provided on the inner surface of this mold. The molten resin material for forming the covering member  71  is filled into the mold with the sensor holding portion  22  sandwiched from both sides in the sandwiching direction X 1  by the first and second pins. Then, the covering member  71  is formed by solidifying the resin material. In taking out the covering member  71  from the mold, the first and second pins are also pulled out from the covering member  71 . Therefore, the covering member  71  is formed with the first exposing hole  72  at a position where the first pin was present and the second exposing hole  73  at a position where the second pin was present. 
     Functions and effects of this embodiment are described. 
     (1) The busbar unit  10  to be electrically connected to the stator coil of the stator is provided with the busbar  13 , the temperature sensor  14  for detecting the temperature of the busbar  13  and the covering member  71  made of insulating resin for covering the busbar  13  and the temperature sensor  14 . The temperature sensor  14  includes the thermistor element  41  and the case  51  for accommodating the thermistor element  41 . The busbar  13  includes the sensor holding portion  22  for holding the temperature sensor  14 . The sensor holding portion  22  includes the first supporting portion  31  having the first contact surface  31  configured to contact the case  51 , the second supporting portion  32  having the second contact surface  32   a  facing the first contact surface  31   a  and configured to contact the case  51 , and the coupling portion  33  coupling the one end parts of the first and second supporting portions. The sensor holding portion  22  holds the temperature sensor  14  by sandwiching the case  51  by the first and second contact surfaces  31   a ,  32   a . The covering member  71  covers the outsides of the sensor holding portion  22  and the case  51 . 
     According to the above aspect, the sensor holding portion  22  sandwiches the case  51  by the first and second contact surfaces  31   a ,  32   a . In this embodiment, the first contact surface  31   a  is pressed against the inserting portion  57  and the second contact surface  32   a  is pressed against the inserting portion  57  by press-fitting the inserting portion  57  of the case  51  between the first and second supporting portions  31 ,  32 . Accordingly, the first and second contact surfaces  31   a ,  32   a  in contact with the case  51  are held in close contact with the case  51  on both sides in the sandwiching direction X 1 . Therefore, the temperature of the busbar  13  is easily transferred to the thermistor element  41  via the case  51 . As a result, accuracy in detecting the temperature of the busbar  13  by the temperature sensor  14  can be improved. 
     Further, since the sensor holding portion  22  and the case  51  are covered by the covering member  71 , the detachment of the temperature sensor  14  from the sensor holding portion  22  is suppressed by the covering member  71 . 
     (2) The case  51  has the abutting surface  56  configured to abut on the sensor holding portion  22 . The abutting surface  56  is facing the sensor holding portion  22  in the direction orthogonal to the sandwiching direction X 1  of sandwiching the case  51  by the first and second contact surfaces  31   a ,  32   a.    
     According to the above aspect, the temperature sensor  14  is positioned in the direction orthogonal to the sandwiching direction X 1  with respect to the sensor holding portion  22  by the abutment of the abutting surface  56  on the sensor holding portion  22 . In this embodiment, the abutting surface  56  abuts on the first supporting portion  31  from the longitudinal direction of the busbar body  21 , whereby the temperature sensor  14  is positioned in the longitudinal direction of the busbar body  21  with respect to the sensor holding portion  22  and the case  51  is positioned in the longitudinal direction of the case  51  with respect to the sensor holding portion  22 . Therefore, the temperature sensor  14  is easily attached to the sensor holding portion  22 . 
     (3) A part of the case  51  and the sensor holding portion  22  are respectively integrated with the covering member  71  while being covered by the covering member  71 . The covering member  71  includes the first exposing hole  72  for exposing a part of the surface of the first supporting portion  31  on the side opposite to the first contact surface  31   a  to outside and the second exposing hole  73  for exposing a part of the surface of the second supporting portion  32  on the side opposite to the second contact surface  32   a  to outside. The first and second exposing holes  72 ,  73  extend along the sandwiching direction X 1  of sandwiching the case  51  by the first and second contact surfaces  31   a ,  32   a.    
     According to the above aspect, the first pin for forming the first exposing hole  72  and the second pin for forming the second exposing hole  73  are provided in the mold for forming the covering member  71 . The first pin extends along the sandwiching direction X 1  and abuts on the surface of the first supporting portion  31  on the side opposite to the first contact surface  31   a  inside the mold. The second pin extends along the sandwiching direction X 1  and abuts on the surface of the second supporting portion  32  on the side opposite to the second contact surface  32   a  inside the mold. Accordingly, the covering member  71  is formed with the sensor holding portion  22  sandwiched from the both sides in the sandwiching direction X 1  by the first and second pins. Thus, when the molten resin material for forming the covering member  71  is filled into the mold, the separation of the first and second supporting portions  31 ,  32  can be suppressed by the first and second pins. Therefore, it can be suppressed that close contact between the case  51  and the sensor holding portion  22  is reduced when the covering member  71  is formed. 
     Further, since the covering member  71  is integrated by covering a part of the case  51  and the sensor holding portion  22 , the temperature sensor  14  is undetachable from the busbar  13 . Therefore, the temperature sensor  14  can be firmly fixed to the busbar  13  as compared to the case where a temperature sensor is detachable from a busbar. 
     (4) The case  51  includes the retaining protrusion  58  projecting outwardly of the case  51  from the second outer side surface  52   b . The retaining protrusion  58  is integrated with the covering member  71  while being covered by the covering member  71 . 
     According to the above aspect, since the retaining protrusion  58  is fit in the covering member  71 , a relative movement of the retaining protrusion  58  with respect to the covering member  71  is suppressed. Therefore, the detachment of the temperature sensor  14  from the busbar  13  can be suppressed not only by sandwiching the case  51  by the sensor holding portion  22 , but also by physically fitting the retaining protrusion  58  and the covering member  71 . 
     (5) The case  51  has the abutting surface  56  configured to abut on the sensor holding portion  22  on the one end part and the retaining protrusion  58  on the other end part, out of the both end parts in the sandwiching direction X 1  of the case  51 . The abutting surface  56  is facing the sensor holding portion  22  in the direction orthogonal to the sandwiching direction X 1 . The retaining protrusion  58  has the facing surface  59  facing the sensor holding portion  22 . The facing direction of the facing surface  59  and the sensor holding portion  22  is the same as the facing direction X 2  of the abutting surface  56  and the sensor holding portion  22 . The positions of the abutting surface  56  and the facing surface  59  are shifted in the facing direction X 2 . 
     According to the above aspect, since the positions of the abutting surface  56  and the facing surface  59  are shifted in the facing direction X 2 , it can be suppressed that the temperature sensor  14  is attached to the sensor holding portion  22  in an improper posture inverted from a proper attachment posture with respect to the sensor holding portion  22  when the case  51  is attached to the sensor holding portion  22 . 
     This embodiment can be modified and carried out as follows. This embodiment and the following modifications can be carried out in combination without technically contradicting. 
     In the above embodiment, the facing surface  59  abuts on the second supporting portion  32  of the sensor holding portion  22 . However, the facing surface  59  may not necessarily abut on the sensor holding portion  22 . Also in this case, an effect similar to the effect (5) of the above embodiment can be obtained if the positions of the abutting surface  56  and the facing surface  59  are shifted in the facing direction X 2 . 
     In the above embodiment, the facing surface  59  is provided on the side surface of the retaining protrusion  58 . However, the facing surface  59  may be formed on the case  51  by providing the second outer side surface  52   b  with the step portion  55 . Further, the case  51  may not necessarily have the facing surface  59 . 
     In the above embodiment, the retaining protrusion  58  is provided on the second outer side surface  52   b . However, the retaining protrusion  58  may be provided on the outer side surface other than the first and second outer side surfaces  52   a ,  52   b , out of the outer side surfaces constituting the outer peripheral surface of the case  51 . Further, the case  51  may not necessarily include the retaining protrusion  58 . 
     The covering member  71  may include only either one of the first and second exposing holes  72 ,  73 . Further, the covering member  71  may include neither of the first and second exposing holes  72 ,  73 . 
     In the above embodiment, the abutting surface  56  is formed on the case  51  by providing the step portion  55 . However, the retaining protrusion  58  may be provided on the first outer side surface  52   a , and a surface on the side of the first end  53   a , out of both side surfaces of the retaining protrusion  58  in the longitudinal direction of the case  51  may be the abutting surface  56 . Further, the case  51  may not necessarily have the abutting surface  56 . 
     In the above embodiment, the inserting portion  57  is inserted into the sensor holding portion  22  along the longitudinal direction of the case  51  and along the longitudinal direction of the busbar body  21 . However, the inserting direction of the inserting portion  57  into the sensor holding portion  22  is not limited to this. For example, the inserting portion  57  may be inserted into between the first and second supporting portions  31 ,  32  along the transverse direction of the case  51  and along the transverse direction of the busbar body  21  when viewed from the plate thickness direction of the busbar body  21 . 
     In the above embodiment, the sensor holding portion  22  has the U shape open on the one side in the transverse direction of the busbar body  21  when viewed from the longitudinal direction of the busbar body  21 . However, the shape of the sensor holding portion  22  is not limited to that of the above embodiment as long as the sensor holding portion  22  includes the first supporting portion  31  having the first contact surface  31   a , the second supporting portion  32  having the second contact surface  32   a  facing the first contact surface  31   a  and the coupling portion  33  coupling the one end parts of the first and second supporting portions  31 ,  32 . For example, the sensor holding portion  22  may include the coupling portion  33  having an arcuate shape when viewed from the longitudinal direction of the busbar body  21 . Further, for example, the sensor holding portion  22  may have a U shape open on one side in the longitudinal direction of the busbar body  21  when viewed from the transverse direction of the busbar body  21 . 
     The shape of the busbar body  21  is not limited to that of the above embodiment. For example, a busbar body may be in the form of a linearly extending strip. 
     In the above embodiment, the busbar  13  includes the sensor holding portion  22  in the one end part in the longitudinal direction of the busbar  13 . However, the position of the sensor holding portion  22  in the busbar  13  is not limited to this. For example, the busbar  13  may include the sensor holding portion  22  in a central part in the longitudinal direction of the busbar  13 . 
     In the above embodiment, copper and copper alloy are cited as examples of the material of the busbar  13 . However, the material of the busbar  13  is not limited to these if the material is a metal material. For example, the busbar  13  may be made of aluminum or aluminum alloy. 
     The busbar  13  may not necessarily be the busbar serving as the neutral point of the stator coil. The busbar  13  only has to be a busbar provided in the busbar unit  10  to supply power to the stator coil. 
     In the above embodiment, the covering member  71  is formed integrally with the sensor holding portion  22  and the case  51  by insert molding. However, the covering member  71  may not necessarily be formed by insert molding as long as the covering member  71  is made of insulating resin and covers the outsides of the sensor holding portion  22  and the case  51 . For example, the covering member  71  may be a cover formed separately from the sensor holding portion  22  and the case  51  and to be mounted to cover the sensor holding portion  22  and the case  51  after the case  51  is inserted into the sensor holding portion  22 . Further, the covering member  71  may be, for example, made of insulating resin applied to the sensor holding portion  22  and the case  51 . 
     The busbar unit  10  may be configured to be capable of detecting a temperature at a neutral point of a three-phase coil of a three-phase alternating current rotating electric machine. For example, the busbar  13  may be configured to be connected to a neutral line constituting the neutral point of the three-phase coil of the three-phase alternating current rotating electric machine or may be configured as the neutral point itself. 
     As shown in  FIG.  4   , the sensor holding portion  22  of the embodiment may be configured to as a pinch clip or U-shaped clip for clipping the temperature sensor  14  at a position matching or corresponding to the thermistor element  41 . 
     As shown in  FIG.  2   , the busbar  13  can have a distal surface or first end surface intersecting or orthogonal to the longitudinal direction (arrow C) of the busbar  13 . The first supporting portion  31  of the sensor holding portion  22  can have a side end surface intersecting or orthogonal to the longitudinal direction (arrow C) of the busbar  13 . This side end surface of the first supporting portion  31  may be called a second end surface of the busbar  13 . As shown in  FIG.  4   , the first and second end surfaces of the busbar  13  may be shifted in the longitudinal direction (arrow C) of the busbar  13  and/or the thickness direction (arrow A) of the busbar  13 . The first and second end surfaces of the busbar  13  can respectively contact the abutting surface  56  and the facing surface  59  of the case  51 . The first and second end surfaces of the busbar  13  and the abutting surface  56  and the facing surface  59  of the case  51  are an example of a stopper for positioning the case  51  with respect to the busbar  13 . 
     In several implementation examples, the outer surfaces of the busbar  13  (second contact surface  32   a ) and the case  51  may be directly in contact outside the case  51  as shown in  FIG.  4    or may form a metal-to-plastic contact surface or metal-to-plastic planar interface). 
     In several implementation examples, the inner surface of the case  51  and the outer surface of the thermistor element  41  may be directly in contact inside the case  51  as shown in  FIG.  4    or may form a plastic-to-plastic contact surface or plastic-to-plastic planar interface). 
     In several implementation examples, as shown in  FIG.  4   , a wall thickness of the case  51  at a position where the case  51  is sandwiched by the second contact surface  32   a  of the busbar  13  and the thermistor element  41  may be equal to a shortest distance between the second contact surface  32   a  of the busbar  13  and the outer surface of the thermistor element  41 . 
     In several implementation examples, as shown in  FIG.  4   , a wall thickness of the case  51  at a position where the case  51  is sandwiched by the first supporting portion  31  of the busbar  13  and the thermistor element  41  may be equal to a shortest distance between the first supporting portion  31  of the busbar  13  and the outer surface of the thermistor element  41 . 
     In several implementation examples, the distal end of the busbar  13  and the sensor holding portion  22  in the longitudinal direction (arrow C) may be covered by the covering member  71  and may not project from the covering member  71  as shown in  FIGS.  4  and  5   . 
     In several implementation examples, as shown in  FIGS.  4  and  5   , the temperature sensor  14  may include a first length part embedded in the covering member  71  and a second length part projecting from the covering member  71  without being embedded in the covering member  71 . For example, the entire thermistor element  41  may be included in the first length part of the temperature sensor  14 . The step portion  55  and the retaining protrusion  58  of the case  51  may be included in the first length part of the temperature sensor  14  and may be embedded in the covering member  71  so as not to be exposed from the covering member  71 . 
     The present disclosure includes the following implementation example. Reference signs of several constituent elements of the illustrative embodiment are given not for limitation, but for understanding assistance. Some of features described in the following implementation example may be omitted or several of the features described in the implementation example may be selected or extracted and combined. 
     [Addendum 1] A busbar unit ( 10 ) according to one or more implementation examples of the present disclosure can be configured to be capable of detecting a temperature of a neutral point of a three-phase coil of a three-phase alternating current rotating electric machine and provided with a temperature sensor ( 14 ), a busbar ( 13 ) and an insulating resin cover ( 71 ), wherein: 
     the temperature sensor ( 14 ) can include a thermistor element ( 41 ) and an insulating resin case ( 51 ) for accommodating the thermistor element ( 41 ), the busbar ( 13 ) may be configured to be electrically connected to a neutral line constituting the neutral point of the three-phase coil of the three-phase alternating current rotating electric machine or configured as the neutral point itself and can have a longitudinal direction (C), a mount surface ( 32   a ) configured such that the temperature sensor ( 14 ) is mounted thereon and a clip ( 22 ) for clipping the temperature sensor ( 14 ) on the mount surface ( 32   a ) at a position corresponding to the thermistor element ( 41 ), and the insulating resin cover ( 71 ) can be configured to cover a part of the busbar ( 13 ) and a part of the temperature sensor ( 14 ) and the clip ( 22 ) may be included in the part of the busbar ( 13 ) covered by the insulating resin cover ( 71 ). 
     LIST OF REFERENCE NUMERALS 
     
         
         
           
               10  busbar unit 
               13  busbar 
               14  temperature sensor 
               21  busbar body 
               22  sensor holding portion 
               31  first supporting portion 
               31   a  first contact surface 
               32  second supporting portion 
               32   a  second contact surface 
               33  coupling portion 
               41  thermistor element 
               42  wire 
               43  connector portion 
               51  case 
               52   a  first outer side surface 
               52   b  second outer side surface 
               53   a  first end 
               53   b  second end 
               54  element accommodating portion 
               55  step portion 
               56  abutting surface 
               57  inserting portion 
               58  retaining protrusion 
               59  facing surface 
               61  sealing resin 
               71  covering member 
               72  first exposing hole 
               73  second exposing hole 
             D 1  distance 
             T 1  thickness 
             X 1  sandwiching direction 
             X 2  facing direction