Patent Publication Number: US-2023163491-A1

Title: Connector

Description:
CONNECTOR 
     This application claims priority from Japanese Patent Application No. 2021-190551 filed on Nov. 24, 2021, the disclosure of which is herein incorporated by reference in its entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to a connector for connecting between an electrical equipment and a power line cable through which an electric power is to be supplied to the electrical equipment. 
     BACKGROUND OF THE INVENTION 
     There is known a connector for connecting between an electrical equipment and a power line cable. A connector disclosed in JP2021-89881A is an example of such a connector. This Japanese Patent Application Publication discloses that busbars are inserted in respective insertion holes provided in a terminal block (called “housing” in this Publication) of the connector, and that a seal member is disposed between each of the busbars and a wall surface of a corresponding one of the insertion holes. 
     SUMMARY OF THE INVENTION 
     By the way, in a construction, as shown in the above-identified Japanese Patent Application Publication, in which the busbars are inserted in the respective insertion holes provided in the terminal block, and in which the seal member is disposed between each of the busbars and the wall surface of the corresponding one of the insertion holes, if vibration generated in the electrical equipment is transmitted to each busbar via the corresponding power line cable, the busbar is vibrated in the corresponding insertion hole whereby load applied to the busbar is increased. The increase of the load applied to the busbar causes a risk that durability of the busbar could be reduced. Further, the vibration of the busbar makes it difficult to ensure sufficient squeeze (i.e., amount of compression) of the seal member, thereby causing risks that oil could leak through the seal member and that water could enter through the seal member. 
     The present invention was made in view of the background art described above. It is therefore an object of the present invention to provide a connector including: a terminal block; a busbar inserted in an insertion hole of the terminal block; a seal member disposed between the busbar and the insertion hole, wherein the connector is capable of reducing load applied the busbar due to vibration of the busbar, and suppressing leakage of oil through the seal member and entrance of water through the seal member. 
     The object indicated above is achieved according to the following aspects of the present invention. 
     According to a first aspect of the invention, there is provided a connector including: (a) a terminal block; (b) an elongated busbar which is inserted in an insertion hole provided in the terminal block so as to be held by the terminal block in a cantilever manner; (c) a seal member which is disposed between the busbar and a wall surface of the insertion hole and which closes a gap defined between the busbar and the wall surface of the insertion hole; and (d) a protection member which is disposed in the gap defined between the busbar and the wall surface of the insertion hole and which is located between the seal member and an opening of the insertion hole. 
     According to a preferred arrangement of the first aspect of the invention, the protection member is made of a material that is more rigid than a material of which the seal member is made. 
     Further, according to another preferred arrangement of the first aspect of the invention, the busbar is an elongated plate member that is inserted in the seal member and the protection member each of which has a generally annular shape, wherein the protection member has an outside dimension that is smaller than a dimension of the insertion hole in which the seal member is fitted, each of the outside dimension of the protection member and the dimension of the insertion hole being a dimension measured in a thickness direction of the busbar that is the elongated plate member. 
     According to a second aspect of the invention, in the connector according to the first aspect of the invention, there is further provided a nut having a surface in which a threaded hole is provided, wherein the nut is press-fitted in the terminal block and is located on a side of the opening of the insertion hole, such that the surface of the nut is in contact with the busbar. 
     According to a third aspect of the invention, in the connector according to the second aspect of the invention, the protection member includes a projecting portion projecting toward the nut that is located on the side of the opening of the insertion hole. 
     According to a fourth aspect of the invention, in the connector according to any one of the first through third aspects of the invention, the protection member is made of resin. 
     According to a fifth aspect of the invention, in the connector according to any one of the first through fourth aspects of the invention, the busbar is to be connected to a power line cable extending from a stator of a rotary electric machine. 
     In the connector according to the first aspect of the invention, the protection member is disposed in the gap defined between the busbar and the wall surface of the insertion hole and which is located between the seal member and an opening of the insertion hole. Therefore, even when vibration generated in an electrical equipment is transmitted to the busbar, amount of deformation of the busbar is limited owing to contact of the busbar with the protection member. Consequently, load applied to the busbar is reduced so that it is possible to suppress reduction of durability of the busbar. Moreover, since the amount of deformation of the busbar is limited upon vibration of the busbar, it is possible to ensure sufficient squeeze of the seal member, thereby suppressing leakage of oil through the seal member and also entrance of water through the seal member. 
     In the connector according to the second aspect of the invention, the nut is press-fitted in the terminal block and is located on the side of the opening of the insertion hole, such that the surface (in which the threaded hole is provided) of the nut is in contact with the busbar. Therefore, with a bolt being provided to penetrate through the busbar so as to be screwed in the nut, it is possible to easily fix an end portion of the busbar to the terminal block. 
     In the connector according to the third aspect of the invention, the protection member includes a projecting portion projecting toward the nut that is located on the side of the opening of the insertion hole, such that a distal end of the projecting portion can be brought into contact with the nut. Therefore, with the projecting portion being brought into contact with the nut, movement of the protection member toward the opening of the insertion hole is limited. Further, regarding the seal member disposed between the protection member and a bottom of the insertion hole, too, its movement toward the opening of the insertion hole is limited, so that the seal member is prevented from being removed out of the insertion hole. 
     In the connector according to the fourth aspect of the invention, the protection member is made of resin, so that it is possible to prevent the seal member being damaged by the protection member when the protection member and the seal member are brought into contact with each other. 
     In the connector according to the fifth aspect of the invention, when vibration is generated upon operation of the rotary electric machine and the vibration is transmitted to the busbar via the power line cable extending from the stator, the busbar is vibrated but the amount of deformation of the busbar is limited by the protection member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a view showing an internal structure of a vehicle power transmission device to which the present invention is applied; 
         FIG.  2    is a perspective view showing a connector and a stator of a rotary electric machine that are shown in  FIG.  1   ; 
         FIG.  3    is an overall view showing the connector, as seen in a direction in which bolts are screwed; 
         FIG.  4    is a perspective view showing, in enlargement, a part of the connector; 
         FIG.  5    is a cross-sectional view taken in line B-B (that passes through a busbar) in  FIG.  3   ; 
         FIG.  6    is a view showing the cross-sectional view of  FIG.  5   , in a perspective manner; 
         FIGS.  7 A and  7 B  are views showing the busbar, a nut, a packing seal and a holder that are extracted from  FIG.  6   ; and 
         FIG.  8    is a cross sectional view showing, in enlargement, a first extending portion that is shown in  FIG.  5   . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     Hereinafter, there will be described preferred embodiment in detail with reference to the accompanying drawings. It is noted that figures of the drawings are simplified or deformed as needed, and each portion is not necessarily precisely depicted in terms of dimension ratio, shape, etc. EMBODIMENT 
       FIG.  1    is a view showing an internal structure of a vehicle power transmission device  10  to which the present invention is applied. As shown in  FIG.  1   , a rotary electric machine MG is stored inside a casing  12  of the vehicle power transmission device  10 . 
     The rotary electric machine MG includes a stator  14  and a rotor  16  that is disposed on an inner peripheral side of the stator  14 . The stator  14  is fixed to the casing  12  through three bolts  18   a - 18   c . The rotor  16  is held by the casing  12  and is rotatable about an axis CL. 
     The vehicle power transmission device  10  includes a connector  22  provided to electrically connect between an inverter (not shown) and three stator power line cables  20   a - 20   c  (power line cables) extending from the stator  14 . It is noted that each of the stator power line cables  20   a - 20   c  corresponds to “power line cable” recited in the appended claims. 
       FIG.  2    is a perspective view showing the connector  22  and the stator  14  of the rotary electric machine MG that are shown in  FIG.  1   . 
     The stator  14  includes an annular-shaped stator core  24  and stator coils  26  that protrude from an axially opposite ends of the stator core  24 , i.e., opposite ends of the stator core  24  that are opposite to each other in a direction of the axis CL. The stator core  24  is constituted by a plurality of disc-shaped electromagnetic steel sheets that are laminated on each other. The stator coils  26  are constituted by a plurality of segments  28  that pass through slots (not shown) that are provided in the stator core  24 . Each of the slots extends radially from an inner circumferential surface of the stator core  24  toward an outer peripheral side of the stator core  24 , and penetrates the stator core  24  in the direction of the axis CL. Each of the segments  28  has a U-shape, for example, and passes through a corresponding one of the slots from one of axially opposite sides (i.e., opposite sides in the direction of the axis CL) of the stator core  24  to the other of the axially opposite sides of the stator core  24 . Further, each of the segments  28  is connected at its end portion with another of the segments  28  in the other of the axially opposite sides of the stator core  24  . . . It is noted that, in  FIG.  2   , some of the segments  28  are shown while the other segments  28  are not shown. 
     The connector  22  is provided to connect between the stator power line cables  20   a - 20   c  (extending from the stator  14 ) and power-supply line cables (not shown) extending from the inverter. The connector  22  includes: a connector housing  30  as a casing body; a connector main body  32  disposed inside the housing  30 ; and three plates  36   a - 36   c  (hereinafter simply referred to as “plates  36 ” unless they are to be distinguished from one another) that are fixed to the connector main body  32  through respective three bolts  34   a - 34   c  (hereinafter simply referred to as “bolts  34 ” unless they are to be distinguished from one another). The connector main body  32  cooperates with the housing  30  covering the connector main body  32 , to constitute a terminal block  39 . 
     The housing  30  is made of aluminum alloy, for example, and is fixedly disposed outside the casing  12 . The connector main body  32  is made of resin, and is disposed inside the housing  30 . Each of the plates  36  has an L shape, and is fixed to the connector main body  32  through a corresponding one of the bolts  34 . Elongated intermediate members  38  are connected to the respective plates  36  by suitable means such as caulking. The stator power line cables  20   a - 20   c  are connected at their distal end portions with distal end portions of the respective intermediate members  38  by suitable means such as welding, so that the stator power line cables  20   a - 20   c  are electrically connected to the respective plates  36   a - 36   c.    
       FIG.  3    is an overall view showing the connector  22 , as seen in a direction in which the bolts  34  are screwed.  FIG.  4    is a perspective view showing, in enlargement, a part of the connector  22 , wherein the part of the connector  22  includes a portion of the connector  22  in which busbars  50   a - 50   c  protrude. It is noted that the bolts  34  and the plates  36  shown in  FIG.  2    are not shown in  FIGS.  3  and  4   . 
     As shown in  FIG.  3   , the connector main body  32  is substantially covered by the housing  30  so as to be protected by the housing  30 . The housing  30  is disposed outside the casing  12  in an assembled state in which the connector  22  is assembled in the vehicle power transmission device  10 . The casing  12  has a rectangular-shaped through-hole that communicates between an inner space and an outer space, and the terminal block  39  is fixed to the casing  12  such that the rectangular-shaped through-hole is closed by the terminal block  39 . With the terminal block  39  being fixed to the casing  12 , a peripheral end of the housing  30  is in contact with a surrounding portion of an outer wall surface of the casing  12 , which surrounds the above-described rectangular-shaped through-hole, so that an extending portion  42  extending from a surface  40  of the connector main body  32  is located in the inner space of the casing  12 . 
     The connector main body  32 , which is made of the resin, has the surface  40  from which the extending portion  42  extends perpendicularly to the surface  40 . In the assembled state in which the connector  22  is assembled in the vehicle power transmission device  10 , the surface  40  of the connector main body  32  faces the inner space of the casing  12 , so that the extending portion  42  is located in the inner space of the casing  12 . 
     The extending portion  42  includes first through third extending portions  48   a - 48   c , wherein the first and second extending portions  48   a ,  48   b  are separated from each other by a first partition wall  44  that extends from the surface  40  perpendicularly to the surface  40 , and the second and third extending portions  48   b ,  48   c  are separated from each other by a second partition wall  46  that extends from the surface  40  perpendicularly to the surface  40 . The first through third extending portions  48   a - 48   c  have respective insertion holes  58  in which the respective busbars  50   a - 50   c  are inserted. 
     Each of the busbars  50   a - 50   c  is an elongated member constituted by a plate member that is made of copper, for example. The connector main body  32  is formed, by an insert forming process, in a state in which the busbars  50   a - 50   c  are inserted in the respective insertion holes  58 . 
     A cutout  52   a  is provided in a bolt-receiving portion of the first extending portion  48   a  in which the bolt  34   a  is received, such that an end portion of the busbar  50   a  is exposed through the cutout  52   a  from the insertion hole  58  of the first extending portion  48   a . The end portion of the busbar  50   a  is provided with a through-hole  54   a  thought which the bolt  34   a  is to pass. A nut  56   a  is provided on a side of an opening of the insertion hole  58 , such that the nut  56   a  is in contact with the end portion of the busbar  50   a  in which the through-hole  54   a  is provided. More specifically, with the nut  56   a  being fixed in a predetermined position in the first extending portion  48   a , the busbar  50   a  is in contact with a surface  66  (see  FIG.  8   ) of the nut  56   a , such that the through-hole  54   a  of the busbar  50   a  overlaps with a threaded hole  64  (see  FIG.  8   ) that is provided in the surface  66 , namely, an axis of the through-hole  54   a  is substantially aligned with an axis of the threaded hole  64 . The surface  66  of the nut  56   a  is defined as one of opposite end surfaces of the nut  56   a  that are opposite to each other in an axial direction of the threaded hole  64 , wherein the one of the opposite end surfaces is opposed to the busbar  50   a.    
     The nut  56   a  has a rectangular outer shape, and is disposed in a space located on one of opposite sides of the busbar  50   a  that is remote from the bolt  34   a , so that the bolt  34   a  is screwed in the threaded hole  64  of the nut  56   a . The nut  56   a  is fixed in the first extending portion  48   a  constituting a part of the terminal block  39 , with two side surfaces of the nut  56   a  being press-fitted in respective surfaces of the first extending portion  48   a , wherein the two side surfaces are parallel to the first and second partition walls  44 ,  46 . The surfaces of the first extending portion  48   a , in which the two side surfaces of the nut  56   a  being press-fitted, are provided with stopper protrusion portions  59   a  for inhibiting displacement of the press-fitted nut  56   a  relative to the first extending portion  48   a . The bolt  34   a  is screwed in the nut  56   a , with the bolt  34   b  passing through the through-hole  54   a  of the busbar  50   a  and a through-hole (not shown) of the plate  36   a , whereby the busbar  50   a  and the plate  36   a  are integrally fixed to each other. Thus, the busbar  50   a  is connected through the plate  36   a  to the stator power line cable  20   a  that extend from the stator  14  of the rotary electric machine MG. 
     A cutout  52   b  is provided in a bolt-receiving portion of the second extending portion  48   b  in which the bolt  34   b  is received, such that an end portion of the busbar  50   b  is exposed through the cutout  52   b  from the insertion hole  58  of the second extending portion  48   b . The end portion of the busbar  50   b  is provided with a through-hole  54   b  thought which the bolt  34   b  is to pass. A nut  56   b  is provided on a side of an opening of the insertion hole  58 , such that the nut  56   b  is in contact with the end portion of the busbar  50   b  in which the through-hole  54   b  is provided. More specifically, with the nut  56   b  being fixed in a predetermined position in the second extending portion  48   b , the busbar  50   b  is in contact with a surface of the nut  56   b , such that the through-hole  54   b  of the busbar  50   b  overlaps with a threaded hole that is provided in the surface of the nut  56   b , namely, an axis of the through-hole  54   b  is substantially aligned with an axis of the threaded hole. 
     The nut  56   b  has a rectangular outer shape, and is disposed in a space located on one of opposite sides of the busbar  50   b  that is remote from the bolt  34   b , so that the bolt  34   b  is screwed in the threaded hole of the nut  56   b . The nut  56   b  is fixed in the second extending portion  48   b  constituting a part of the terminal block  39 , with two side surfaces of the nut  56   b  being press-fitted in respective surfaces of the second extending portion  48   b , wherein the two side surfaces are parallel to the first and second partition walls  44 ,  46 . The surfaces of the second extending portion  48   b , in which the two side surfaces of the nut  56   b  being press-fitted, are provided with stopper protrusion portions  59   b  for inhibiting displacement of the press-fitted nut  56   b  relative to the second extending portion  48   b . The bolt  34   b  is screwed in the nut  56   b , with the bolt  34   b  passing through the through-hole  54   b  of the busbar  50   b  and a through-hole (not shown) of the plate  36   b , whereby the busbar  50   b  and the plate  36   b  are integrally fixed to each other. Thus, the busbar  50   b  is connected through the plate  36   b  to the stator power line cable  20   b  that extend from the stator  14  of the rotary electric machine MG. 
     A cutout  52   c  is provided in a bolt-receiving portion of the third extending portion  48   c  in which the bolt  34   c  is received, such that an end portion of the busbar  50   c  is exposed through the cutout  52   c  from the insertion hole  58  of the third extending portion  48   c . The end portion of the busbar  50   c  is provided with a through-hole  54   c  thought which the bolt  34   c  is to pass. A nut  56   c  is provided on a side of an opening of the insertion hole  58 , such that the nut  56   c  is in contact with the end portion of the busbar  50   c  in which the through-hole  54   c  is provided. More specifically, with the nut  56   c  being fixed in a predetermined position in the third extending portion  48   c , the busbar  50   c  is in contact with a surface of the nut  56   c , such that the through-hole  54   c  of the busbar  50   c  overlaps with a threaded hole that is provided in the surface of the nut  56   c , namely, an axis of the through-hole  54   c  is substantially aligned with an axis of the threaded hole. 
     The nut  56   c  has a rectangular outer shape, and is disposed in a space located on one of opposite sides of the busbar  50   c  that is remote from the bolt  34   c , so that the bolt  34   c  is screwed in the threaded hole of the nut  56   c . The nut  56   c  is fixed in the third extending portion  48   c  constituting a part of the terminal block  39 , with two side surfaces of the nut  56   c  being press-fitted in respective surfaces of the third extending portion  48   c , wherein the two side surfaces are parallel to the first and second partition walls  44 ,  46 . The surfaces of the third extending portion  48   c , in which the two side surfaces of the nut  56   c  being press-fitted, are provided with stopper protrusion portions  59   c  for inhibiting displacement of the press-fitted nut  56   c  relative to the third extending portion  48   c . The bolt  34   c  is screwed in the nut  56   c , with the bolt  34   c  passing through the through-hole  54   c  of the busbar  50   c  and a through-hole (not shown) of the plate  36   c , whereby the busbar  50   c  and the plate  36   c  are integrally fixed to each other. Thus, the busbar  50   c  is connected through the plate  36   c  to the stator power line cable  20   c  that extend from the stator  14  of the rotary electric machine MG. 
       FIG.  5    is a cross-sectional view taken in line B-B (that passes through a widthwise center of the busbar  50   a ) in  FIG.  3    that shows the connector  22 .  FIG.  6    is a view showing the cross-sectional view of  FIG.  5   , in a perspective manner As shown in  FIGS.  5  and  6   , the first extending portion  48   a  extending from the surface  40  of the connector main body  32  is provided with the insertion hole  58  that is perpendicular to the surface  40 , and the busbar  50   a  is inserted in the insertion hole  58 . Thus, the busbar  50   a  is held by the connector main body  32  in a cantilever manner 
     The insertion hole  58  is provided to surround the busbar  50   a . In the insertion hole  58 , a packing seal  60  as well as the busbar  50   a  is inserted, such that the packing seal  60  is provided in an annular gap between the busbar  50   a  and a wall surface  58 a of the insertion hole  58 , so as to close the annular gap. The packing seal  60  is placed adjacent to a bottom of the insertion hole  58 . With the packing seal  60  being provided in the insertion hole  58 , it is possible to suppress leakage of oil stored in the inner space of the casing  12  toward the outer space, and also entrance of water to the inner space of the casing  12  from the outer space. It is noted that the packing seal  60  corresponds to “seal member” recited in the appended claims. A holder  62  described below does not have a sealing function. 
     From a state shown in  FIGS.  5  and  6    in which the busbar  50   a  is superposed on the nut  56   a , the plate  36   a  is superposed on the busbar  50   a , and then the bolt  34   a  is screwed in the nut  56   a , whereby the busbar  50   a  and the plate  36   a  are integrally fixed to each other. The busbar  50   a  is made of a copper material while the nut  56   a  is made of an iron material, so that the busbar  50   a  and the nut  56   a  are different from each other in terms of coefficient of linear expansion. Therefore, at an extremely low temperature, a gap is formed between the busbar  50   a  and the nut  56   a  due to the difference in the coefficient of linear expansion, so that the busbar  50   a  is vibrated if vibration generated in the stator  14  during operation of the rotary electric machine MG is transmitted to the busbar  50   a  via the stator power line cable  20   a  and the plate  36   a . If the busbar  50   a  is vibrated, the busbar  50   a  is repeatedly deformed whereby load is applied to the busbar  50   a  thereby causing a risk that durability of the busbar  50   a  could be reduced. Moreover, during vibration of the busbar  50   a , if the packing seal  60  closing the gap between the busbar  50   a  and the wall surface  58   a  of the insertion hole  58  is not sufficiently squeezed in a portion thereof, there are risks that oil could leak outwardly through the portion of the packing seal  60  and that water could enter the inner space of the casing  12  through the portion of the packing seal  60 . 
     On the other hand, in the present embodiment, a holder  62  is disposed in the gap defined in the insertion hole  58 , i.e., defined between the busbar  50   a  and the wall surface  58   a  of the insertion hole  58 , so as to limit amount of deformation of the busbar  50   a  when the busbar  50   a  is vibrated. The holder  62  is made of resin or other material more rigid than a material of which the packing seal  60  is made, and is disposed between the packing seal  60  and the nut  56   a  in the insertion hole  58 . That is, the holder  62  is disposed between the packing seal  60  and the opening of the insertion hole  58  in the insertion hole  58 . The holder  62  as well as the packing seal  60  is shaped to surround the busbar  50   a . It is noted that, although the packing seal  60  and the holder  62  are contiguous to each other in a longitudinal direction of the busbar  50   a , i.e., a longitudinal direction of the insertion hole  58  in  FIGS.  5  and  6   , the holder  62  is movable relative to the packing seal  60  in the longitudinal direction of the busbar  50   a , i.e., the longitudinal direction of the insertion hole  58 . It is also noted that the holder  62  corresponds to “protection member” recited in the appended claims. 
       FIGS.  7 A and  7 B  are views showing the busbar  50   a , nut  56   a , packing seal  60  and holder  62  that are extracted from  FIG.  6   , wherein  FIG.  7 A  is a view of the busbar  50   a , nut  56   a , packing seal  60  and holder  62  as seen in direction of arrow D, and  FIG.  7 B  is a perspective view of  FIG.  7 A . As shown in  FIGS.  7 A and  7 B , the packing seal  60  has a generally annular shape so as to surround the busbar  50   a . The packing seal  60  has a through-hole having a rectangular shape in its cross section, such that the busbar  50   a  is inserted in the through-hole of the packing seal  60 . The packing seal  60  presses the busbar  50   a  that is inserted in the through-hole of the packing seal  60 , so that the busbar  50   a  and the packing seal  60  are in close contact with each other. 
     The packing seal  60 , which is inserted in the insertion hole  58 , is provided with annular protrusions  60   a ,  60   b  protruding outwardly. The protrusions  60   a ,  60   b  are in contact with the wall surface  58   a  of the insertion hole  58 , and are deformed or squeezed whereby the gap between the busbar  50   a  and the wall surface  58   a  of the insertion hole  58  is closed by the packing seal  60 . 
     The holder  62  as well as the packing seal  60  is shaped to surround the busbar  50   a . The holder  62  has a through-hole  68  (see  FIGS.  6  and  8   ) having a rectangular shape in its cross section, such that the busbar  50   a  is inserted in the through-hole  68  of the holder  62  as well as in the above-described through-hole of the packing seal  60 . The busbar  50   a  has a dimension L 1  that is slightly smaller than a dimension L 2  of the through-hole  68  of the holder  62  (L 1 &lt;L 2 ), wherein each of the dimensions L 1 , L 2  is a dimension measured in a thickness direction of the busbar  50   a  (see  FIG.  8   ). Therefore, the holder  62  is allowed to be moved relative to the busbar  50   a  in the longitudinal direction of the busbar  50   a.    
     Further, the holder  62  has an outside dimension L 3  that is smaller than a dimension L 4  between mutually opposed portions of the wall surface  58   a  of the insertion hole  58  (L 3 &lt;L 4 ), wherein each of the dimensions L 3 , L 4  is a dimension measured in a thickness direction of the busbar  50   a  (see  FIG.  8   ). Therefore, a small gap is defined between the wall surface  58   a  of the insertion hole  58  and the holder  62  that is inserted in the insertion hole  58 . 
     The holder  62  includes a projecting portion  62   a  toward the nut  56   a  such that a distal end of the projecting portion  62   a  is contactable with the nut  56   a . The projecting portion  62   a  is located in a position in which the distal end of the projecting portion  62   a  is contactable with the nut  56   a . The distal end of the projecting portion  62   a  is located in vicinity to the nut  56   a . Therefore, even in a case in which the holder  62  is moved toward the nut  56   a , the movement of the holder  62  toward the nut  56   a  is limited by contact of the distal end of the projecting portion  62   a  with the nut  56   a.    
       FIG.  8    is a cross sectional view showing, in enlargement, the first extending portion  48   a  that is shown in  FIG.  5   . In a process of manufacturing the connector  22 , the packing seal  60  and the holder  62  are inserted into the insertion hole  58  before the nut  56   a  is press-fitted into the first extending portion  48   a . Specifically described, the packing seal  60  is first inserted into the insertion hole  58  provided in the first extending portion  48   a , and then the holder  62  is inserted into the insertion hole  58 . Then, after the packing seal  60  and the holder  62  have been inserted into the insertion hole  58 , the nut  56   a  is press-fitted into the first extending portion  48   a  whereby a state shown in  FIG.  8    is established. In this state, the nut  56   a  is in contact at the surface  66  (in which the threaded hole  64  opens) with the busbar  50   a.    
     As described above, when the gap is formed between the nut  56   a  and the busbar  50   a , for example, at an extremely low temperature, if vibration generated in the stator  14  is transmitted to the busbar  50   a  via the stator power line cable  20   a  and the plate  36   a , the busbar  50   a  is vibrated in right and left directions in drawing sheet of  FIG.  8   . In this instance, the amount of deformation of the vibrated busbar  50   a  is limited by the holder  62  that is inserted in the insertion hole  58 . 
     If the holder  62  were not provided, the busbar  50   a  could be more displaced within in a range between the mutually opposed portions of the wall surface  58   a  of the insertion hole  58 . On the other hand, in the present embodiment in which the holder  62  is provided, the gap defined between the busbar  50   a  and the wall surface  58   a  of the insertion hole  58  is practically reduced by an amount corresponding to the provision of the holder  62 . Consequently, upon vibration of the busbar  50   a , the busbar  50   a  is deformable only within a limited range, and the amount of deformation of the busbar  50   a  is limited by the holder  62 . Therefore, even when the vibration is transmitted to the busbar  50   a , the amount of deformation of the busbar  50   a  is limited and accordingly the load applied to the busbar  50   a  is reduced so that it is possible to suppress reduction of the durability of the busbar  50   a . Moreover, since the amount of deformation of the busbar  50   a  is limited, it is possible to ensure sufficient squeeze (i.e., amount of compression) of the packing seal  60 , thereby suppressing leakage of oil through the packing seal  60  and also entrance of water through the packing seal  60  from the outer space. 
     Further, since the holder  62  includes the projecting portion  62   a  projecting toward the nut  56   a , the movement of the holder  62  in a direction toward the opening of the insertion hole  58  is limited to a range in which the distal end of the projecting portion  62   a  is not in contact with the nut  56   a . Owing to the projecting portion  62   a  of the holder  62 , the movement of the packing seal  60  that is disposed to be contiguous to the holder  62  is limited, too. Consequently, the packing seal  60  and the holder  62  are practically positioned by the projecting portion  62   a , so that it is possible to prevent the packing seal  60  from being removed out through the opening of the insertion hole  58 . It is noted that a length of the projecting portion  62   a  of the holder  62  is determined such that the distal end of the projecting portion  62   a  is normally spaced apart from the nut  56   a  without interfering with the nut  56   a , and such that the packing seal  60  is not removed out of the insertion hole  58  when the distal end of the projecting portion  62   a  is in contact with the nut  56   a.    
     Although detailed explanation is omitted, also in the insertion hole  58  which is provided in the second extending portion  48   b  and in which the busbar  50   b  is inserted, the holder  62  is inserted in a space defined between the busbar  50   b  and the wall surface  58   a  of the wall hole  58  and is disposed between the packing seal  60  and the opening of the insertion hole  58 . Therefore, when the busbar  50   b  is vibrated, amount of deformation of the busbar  50   b  is limited by the holder  62  whereby durability reduction of the busbar  50   b  due to the deformation is suppressed and the oil leakage through the packing seal  60  and the water entrance through the packing seal  60  are suppressed. 
     Similarly, although detailed explanation is omitted, also in the insertion hole  58  which is provided in the third extending portion  48   c  and in which the busbar  50   c  is inserted, the holder  62  is inserted in a space defined between the busbar  50   c  and the wall surface  58   a  of the wall hole  58  and is disposed between the packing seal  60  and the opening of the insertion hole  58 . Therefore, when the busbar  50   c  is vibrated, amount of deformation of the busbar  50   c  is limited by the holder  62  whereby durability reduction of the busbar  50   c  due to the deformation is suppressed and the oil leakage through the packing seal  60  and the water entrance through the packing seal  60  are suppressed. 
     As described above, in the present embodiment, the holder  62  is disposed in the gap defined between each of the busbars  50   a - 50   c  and the wall surface  58   a  of the insertion hole  58  and which is located between the packing seal  60  and the opening of the insertion hole  58 . Therefore, even when the vibration generated in the rotary electric machine MG is transmitted to the busbars  50   a - 50   c , the amount of deformation of each of the busbars  50   a - 50   c  is limited owing to contact of each of the busbars  50   a - 50   c  with the holder  62 . Consequently, the load applied to each of the busbars  50   a - 50   c  is reduced so that it is possible to suppress reduction of durability of each of the busbars  50   a - 50   c . Moreover, since the amount of deformation of each of the busbars  50   a - 50   c  is limited upon vibration of the busbars  50   a - 50   c , it is possible to ensure sufficient squeeze of the packing seal  60 , thereby suppressing leakage of oil through the packing seal  60  and also entrance of water through the packing seal  60 . 
     Further, in the present embodiment, each of the nuts  56   a - 56   c  is press-fitted in a corresponding one of the first through third extending portions  48   a - 48   c  and is located on the side of the opening of the insertion hole  58 , such that the surface  66  (in which the threaded hole  64  is provided) of each of the nuts  56   a - 56   c  is in contact with a corresponding one of the busbars  50   a - 50   c . Therefore, with each of the bolts  34   a - 34   c  being provided to penetrate through a corresponding one of the busbars  50   a - 50   c  so as to be screwed in a corresponding one the nuts  56   a - 56   c , it is possible to easily fix end portions of the busbars  50   a - 50   c  to the terminal block  39 . Further, the holder  62  includes the projecting portion  62   a  projecting toward each of the nuts  56   a - 56   c  that is located on the side of the opening of the insertion hole  58 , such that the distal end of the projecting portion  62   a  can be brought into contact with each of the nuts  56   a - 56   c . Therefore, with the projecting portion  62   a  being brought into contact with each of the nuts  56   a - 56   c , the movement of the holder  62  toward the opening of the insertion hole  58  is limited. Further, regarding the packing seal  60  disposed between the holder  62  and the bottom of the insertion hole  58 , too, its movement toward the opening of the insertion hole  58  is limited, so that the packing seal  60  is prevented from being removed out of the insertion hole  58 . Moreover, since the holder  62  is made of resin, it is possible to prevent the packing seal  60  being damaged by the holder  62  when the holder  62  and the packing seal  60  are brought into contact with each other. 
     While the preferred embodiment of this invention has been described in detail by reference to the drawings, it is to be understood that the invention may be otherwise embodied. 
     For example, in the above-described embodiment, the nuts  56   a - 56   c  are press-fitted in the respective first through third extending portions  48   a - 48   c , and the bolts  34   a - 34   c  are screwed in the respective nuts  56   a - 56   c , with each of the plates  36   a - 36   c  and a corresponding one of the busbars  50   a - 50   c  being superposed on each other and being clamped between a corresponding one of the bolts  34   a - 34   c  and a corresponding one of the nuts  56   a - 56   c . However, the provision of the nuts  56   a - 56   c  is not essential. For example, each of the through-holes  54   a - 54   c  of the respective busbars  50   a - 50   c  may be modified to a threaded hole, so that the bolts  34   a - 34   c  are screwed in the thread holes of the respective busbars  50   a - 50   c , with each of the plates  36   a - 36   c  and a corresponding one of the busbars  50   a - 50   c  being superposed on each other. In this modified arrangement, too, each of the busbars  50   a - 50   c  is brought into contact with the holder  62  when being vibrated, whereby amount of deformation of each of the busbars  50   a - 50   c  is limited. 
     Further, in the above-described embodiment, the holder  62  is made of resin. However, the holder  62  may be made of other material such as a metal material, as long as the material of the holder  62  is more rigid than a material of which the packing seal  60  is made. 
     It is to be understood that the embodiment described above is given for illustrative purpose only, and that the present invention may be embodied with various modifications and improvements which may occur to those skilled in the art. 
     NOMENCLATURE OF ELEMENTS 
     
         
         
           
               14 : stator 
               20   a - 20   c : stator power line cables (power line cables) 
               22 : connector 
               39 : terminal block 
               50   a - 50   c : busbars 
               56   a - 56   c : nuts 
               58 : insertion hole 
               58   a : wall surface 
               60 : packing seal (seal member) 
               62 : holder (protection member) 
               62   a : projecting portion 
               64 : threaded hole 
               66 : surface MG: rotary electric machine