Patent Publication Number: US-9893450-B2

Title: Electrical connecting member and electrical connector having the same

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
     The present invention relates to an electrical connecting member, which electrically connect between two conductive members so that a large amount of an electrical current can flow through the conductive members. The present invention also relates to an electrical connector having such electrical connecting member(s). 
     Patent Reference has disclosed a conventional electrical connecting member to electrically connect between two conductive members to flow a large electrical current through the conductive members. 
     Patent Reference: Japanese Patent No. 3,566,656 
     According to Patent Reference, the conventional electrical connecting member includes electrically contact pieces, which form two flat thick plate-like conductive members, or cylindrical plugs and a cylindrical socket. Between the two conductive members, a number of electrical connecting elements is arranged, which are made of a sheet metal thinner than that of the electrical contact pieces, and the electrical connecting elements serve as the conventional electrical connecting member. 
     The electrical connecting element includes a plurality of electrical connecting bridges arranged and supported on a support bridge. Each of the electrical connecting bridges is formed of an inverse-V-shaped strip, which is like a triangular frame having a shape of an isosceles triangle with a base side thereof largely removed. The support band is made of a thin sheet metal. The support band includes a center web and a plurality of band portions having an arm shape. The center web extends like a strip in an arrangement direction of the plurality of electrical connecting elements. The arm-like band portions are provided at a plurality of positions, which are provided at a constant pitch in the arrangement direction, and extend both sideways from the center webs like cantilevers. 
     Each of the electrical connecting bridges is supported such that each of both ends of the electrical connecting bridge are clamped with corresponding ends of the band portions. As a result, the electrical connecting bridges supported by the support bands such that the electrical connecting bridges rise diagonally towards one direction relative to a sheet surface of each of the support bands. 
     Therefore, the electrical connecting bridge has a vertex at a center bent part of the inverse-V-shaped, which forms a contact point with one electrical connecting piece. In addition, a contact point to contact with the other electrical connecting piece is formed on both ends of a lower part of each of the electrical connecting bridge. When the electrical connecting element is disposed between the two conductive members, a number of electrical connecting bridges are pressed by the two conductive members. 
     Especially, the center bent part, which is the vertex of the electrical connecting bridge, receives a force from one conductive member, so that the band portion of the support band, which is located on the other conductive member, elastically displaces to twist. As a result, the electrical connecting bridge itself displaces (rotate) so as to reduce the tilting angle thereof relative to the support band. As a result, the two conductive members are electrically connected with a contact pressure to the number of electrical connecting bridges, and form a number of contact points therewith. Therefore, it is achievable to flow a large amount of electrical current via the electrical connecting bridges between the two conductive members. 
     According to Patent Reference, the conventional inverse-V-shaped electrical connecting bridges are supported at their both ends with the support band, so as to be like a fixed-fixed-beam. On the other hand, the band portion of the support band, which supports the electrical connecting bridges, is like a cantilever relative to the center web, extending both sideways like branches from the center web. As a result, in a state of use, where the conventional electrical connecting bridges of the electrical connecting elements are pressed between the two contact pieces, there are problems of the center web&#39;s twisting, large heat generation, and troublesome production. 
     First, in a state of use, once the conventional electrical connecting bridges rotate in a direction of reducing the tilted angle to rise relative to the support bands, the clamp part at the band portion, which is a base portion of the electrical connecting bridge, causes twist on the band portion. From the center web, the band portion extends both sideways like a cantilever. Therefore, the center web receives twist from the both band portions. With this twist, the center web itself may possibly deform. The center web has a function of keeping its posture, while contacting by face with the electrical connecting piece and of keeping posture of the electrical connecting elements being held. However, with the twist of the center web, the center web cannot keep the posture. 
     Second, the conventional electrical connecting bridge of the electrical connecting element is formed as an inverse-V-shaped strip so as to be a fixed-fixed-beam. Therefore the sectional area of each of the electrical connecting bridges is small. Moreover, because of the shape and also in view of the relation with the clamp, the sheet thickness cannot be large so much. Therefore, even in this view, the sectional area is small. For these reasons, when large current flows in the electrical connecting bridge, it is hard to avoid large amount of heat generation. 
     Third, the conventional electrical connecting bridge is clamped at the both ends thereof onto the support band. Therefore, in the electrical connecting element having a number of electrical connecting bridges, the number of clamped positions increases, and the manufacturing process becomes more complicated and troublesome. 
     In view of the above problems, there is provided and invention, an object of which is to provide an electrical connecting member, which can keep stable posture of a plurality of electrical connecting members disposed between two conductive members, has small hear generation when large current flows therebetween, and can be easily produced. Another object of the present invention is to provide an electrically connector having the electrical connecting member. 
     Further objects and advantages of the present invention will be apparent from the following description of the present invention. 
     SUMMARY OF THE INVENTION 
     According to the present invention, it is achievable to solve the above-described problems with an electrical connecting member configured as follows and with an electrical connector having the electrical connecting member. 
     &lt;Electrical Connecting Member&gt; 
     According to a first aspect of the present invention, the electrical connecting member electrically connects between two conductive members, i.e., a first conductive member and a second conductive member. The electrical connecting member has a plurality of contact pieces and a holding member to arrange and hold the contact pieces between the two conductive members. The holding member has elasticity so as to change the holding posture of the contact pieces. 
     According to the first aspect of the present invention, in the electrical connecting member, the contact piece has a first contact portion, a second contact portion, and a held portion. The first contact portion is flat and, and a part of its edge contacts with the first conductive member. The second contact portion is another part of the edge and contacts with the second conductive member. The held portion is a portion to be held by the holding member between the first contact portion and the second contact portion. 
     According to the first aspect of the present invention, the holding member has two base portions, and connecting portions. The base portions are formed to be like strips and extend parallel to each other. The connecting portions are provided in a plurality of positions at certain intervals in a longitudinal direction of the two base portions. Each of the connecting portions has a holding portion to hold the contact piece at the held portion of the contact piece, while having sheet surfaces of adjacent contact pieces parallel in a joining direction (i.e., an extending direction) of the connecting portions, and while being tilted relative to the base portions. 
     According to the first aspect of the present invention, in the electrical connecting member, the contact pieces, which are flat sheet members, are held at the connecting portions of the holding member. The connecting portions extend between two base portions that are parallel to each other. Therefore, the width dimension of each of the contact pieces in the joining direction may be set so as to be close to the length of the connecting portion at the position of the held portion in a conductive members&#39; facing direction, in which the first conductive member and the second conductive member face each other. 
     Furthermore, the width may be set greater than the length of the connecting portion at positions other than that of the held portion in the conductive members&#39; facing direction. As a result, the sectional area can be large, and thereby the electrical resistance is less. Therefore, the heat generation can be small even under large current. In the state of use, when the contact pieces receive contact pressure at the first contact portions and the second contact portions from corresponding conductive members, the first conductive member and the second conductive member, the contact pieces give twisting moment to the connecting portions so as to rotate the connecting portions that hold the contact pieces. At this point, such twisting action occurs only at the connecting portions, but not at the base portions. 
     Furthermore, the base portions are provided at the both ends in the width direction, i.e. two base portions, and the base portions remain at their fixed positions without receiving the twisting at the connecting portions. Therefore, the base portions can keep stable posture relative to the first and the second conductive members. Moreover, since it is just needs to hold the contact pieces with the connecting portions, it is easy to manufacture the electrical connecting member. 
     According to a second aspect of the present invention, each of the contact pieces is formed as a flat piece, in which a first plate portion and a second plate portion are continuously formed. The first plate portion has an edge parallel to the joining direction (i.e., an extending direction of the connecting portion). On this edge, there are provided protrusions at the both ends thereof. The protrusions form the first contact portions. 
     According to the second aspect of the present invention, the second plate portion has slanted edges relative to the joining direction of the connecting portions. On the vertex part (common end part) of the slanted edges, there is formed a second contact portion. 
     According to the first aspect of the present invention, with the configuration described above, while holding the electrical connecting member by one conductive member (the first conductive member or the second conductive member), upon mounting the other conductive member (the second conductive member or the first conductive member) onto the first conductive member towards the second contact portions in the joining direction, being slidably guided with the slanted edges, the other conductive member smoothly moves and then comes to contact with the second contact portions. 
     According to a third aspect of the present invention, in each of the contact pieces, the second plate portion of the contact piece can have a generally triangular shape, and two sides can be formed as slanted edges. With the configuration, the second contact portion formed on the vertex part, the common end part of the two slanted edges, comes to a center position. When the second contact portions receive contact pressure from the other conductive member 
     According to a fourth aspect of the present invention, each of the contact pieces can be formed as an isosceles triangle, such that the two slanted edges of the second plate portion of the contact piece has equal length. With this configuration, it is achievable to mount the second conductive member to the second contact portions, which are formed on the vertex parts (common end parts) of the slanted edges from either side in the joining direction. 
     According to a fifth aspect of the present invention, each of the contact pieces is formed as a flat piece, in which a first plate portion and a second plate portion are continuously formed. The first plate portion has an edge parallel to the joining direction. On this edge, there are provided protrusions at the both ends thereof. The protrusions form the first contact portions. 
     According to the fifth aspect of the present invention, the second plate portion has slanted edges and a vertex portion. The edges of the second plate portion extend from a basal part so as to be slanted relative to the joining direction of the joining member. Being continued from the edges, the vertex part is formed to extend in the joining direction. The second plate portion has slanted edges relative to the joining direction of the connecting portions. On the vertex part (common end part) of the slanted edges, there is formed a second contact portion. With this configuration, the second contact portion can have a larger area to connect to the second conductive member. As a result, it is achievable to obtain stable contact and to be compatible with large current. 
     According to a sixth aspect of the present invention, in each of the contact pieces, the protrusions, i.e., the first contact portions, can have an edge that extends parallel to the joining direction (i.e., the extending direction) of the joining members. With this configuration, similarly to the case of the second contact portions, the first contact portions can have larger areas to contact with the first conductive member. As a result, it is achievable to obtain stable contact and to be compatible with large current. 
     According to a seventh aspect of the present invention, in each of the contact piece, any of the first contact portions, slanted edges, and the second contact portions seventh aspect of preferably have some roundness in the joining direction and the sheet thickness direction. With such roundness, when the contact pieces slide to touch the first conductive member and the second conductive member, the contact pieces will not damage surfaces of the first conductive member and the second conductive member. 
     According to an eighth aspect of the present invention, there are preferably formed holes as carriers on the base portions at positions of the connecting portions in a longitudinal direction. When the holding members are prepared from thin sheet metal, first, the holes as carriers are formed at a part to be base portions. Then, while moving/feeding stepwise by using engaging claws that engage into the holes, the connecting portions are formed by punching out to form the windows or hole portions. The completed holding member will be cut into a suitable length for each use at a position in the longitudinal direction of the base portions. At this point, when the hole portions are provided at the positions described above, the base portions will be cut at a position between adjacent joining members. Therefore, the hole portions are not be shown at the cut sections, and it is convenient to use. 
     According to a ninth aspect of the present invention, the joining members can be formed to extend with a certain tilting angle relative to a longitudinal direction, in which the base portions extends, within a surface where the holding member is present. With this configuration, when the tilting angles of the holding posture of the contact pieces changes during use, since the connecting portions are made long by the tilting angles, the joining members can easily make elastic twisting displacement. Therefore, following the change of the tilting in the holding posture of the contact pieces, the joining members can easily allow the change. 
     &lt;Electrical Connector&gt; 
     According to a tenth aspect of the present invention, an electrical connector includes the above-described electrical connecting member, and a first conductive member to be electrically connected to the electrical connecting member. The first conductive member holds the electrical connecting member at a fixed position so as to form a unit. The unit is configured so as to be able to receive the second conductive member. With the configuration of the unit, it is achievable to integrate the second conductive member into the first conductive member so as to electrically connect to the electrical connecting member, while holding the electrical connecting member with the first conductive member so as not to come off. 
     According to an eleventh aspect of the present invention, the second conductive member may be integrated in the unit from the beginning. 
     According to a twelfth aspect of the present invention, the first conductive member may be configured so as to arrange to hold the plurality of contact pieces in a straight line and receive the second conductive member from a direction perpendicular to the arrangement direction. With the configuration, it is achievable to obtain a flat connector. 
     Moreover, according to a thirteenth aspect of the present invention, the first conductive member has a cylindrical outer circumferential surface or cylindrical inner circumferential surface to hold the electrical connecting member, so as to arrange to hold the plurality of contact pieces on the outer or the inner circumferential surface in the circumferential direction. In addition, the first conductive member can receive the second conductive member, which is formed as a tubular or solid cylindrical member. With this configuration, it is achievable to obtain a round electrical connector. 
     As described above, according to the present invention, the contact pieces to electrically connect between the two conductive members are held by the connecting portions that joint two base portions, which are formed on the holding member and are parallel to each other. Therefore, the contact pieces may be formed as flat members having large dimension but smaller than the length of the connecting portion so as to have larger sectional area. Therefore, it is achievable to restrain heat generation even under large current. 
     In addition, the contact pieces are held at the connecting portion of the holding member when in use, while being tilted. When the tilt is reduced, the connecting portion twists to allow the change of the tilting in the holding posture. Therefore, without causing any deformation on the base portions, it is achievable to stabilize the posture of the base portions relative to the conductive members, and in turn the posture of the electrical connecting member as a whole. Moreover, since the contact pieces just need to have the held portions be held by the connecting portions, the number of holding position can be as small as possible, and thereby the fabrication for the holding can be extremely simple. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1(A) and 1(B)  are views showing an electrical connecting member, a first conductive member, and a second conductive member according to a first embodiment of the present invention, wherein  FIG. 1(A)  is a perspective view thereof and  FIG. 1(B)  is a side view thereof; 
         FIG. 2  is a top perspective view showing the electrical connecting member according to the first embodiment of the present invention; 
         FIG. 3  is a side view showing the electrical connecting member according to the first embodiment of the present invention; 
         FIGS. 4(A) and 4(B)  are bottom perspective views showing the electrical connecting member according to the first embodiment of the present invention, wherein  FIG. 4(A)  is the bottom perspective view thereof before a contact piece is attached to a holding member of the electrical connecting member and  FIG. 4(B)  is the bottom perspective view after the contact piece is attached to the holding member of the electrical connecting member, 
         FIG. 5  is a top perspective view showing a modified example of the electrical connecting member according to the first embodiment of the present invention; 
         FIGS. 6(A) and 6(B)  are bottom perspective views showing an electrical connecting member according to a second embodiment of the present invention, wherein  FIG. 6(A)  is the bottom perspective view thereof before a contact piece is attached to a holding member of the electrical connecting member and  FIG. 6(B)  is the bottom perspective view after the contact piece is attached to the holding member of the electrical connecting member; 
         FIGS. 7(A) and 7(B)  are top perspective views showing an electrical connecting member according to a third embodiment of the present invention, wherein  FIG. 7(A)  is the top perspective view thereof before a contact piece is attached to a holding member of the electrical connecting member and  FIG. 7(B)  is the top perspective view after the contact piece is attached to the holding member of the electrical connecting member; 
         FIGS. 8(A) and 8(B)  are perspective views showing the electrical connecting member when the contact pieces are attached to the holding member of the electrical connecting member according to the third embodiment of the present invention, wherein  FIG. 8(A)  is the bottom perspective view thereof and  FIG. 8(B)  is the top perspective view thereof; 
         FIG. 9  is a perspective view showing a unit including the electrical connecting member according to a fourth embodiment of the present invention; and 
         FIG. 10  is a perspective view showing the electrical connecting member, the first conductive member, and the second conductive member according to a fifth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereunder, embodiments of the present invention will be described with reference to the accompanying drawings. 
     First Embodiment 
     A first embodiment of the present invention will be explained.  FIG. 1(A)  is a perspective view of electrical connecting members according to the first embodiment of the present invention, showing the state that the electrical connecting member is about to receive a second conductive member  30  from a front side thereof in a unit  1 . Here, the unit  1  is composed by mounting the electrical connecting members in a first conductive member  20 .  FIG. 1(B)  is a side view showing the state after receiving the second conductive member  30 . 
     As shown in  FIGS. 1(A) and 1(B) , the first conductive member  20  is formed as a metal block generally having a shape of a 90-degree rotated U-shape when viewed in the side views. The first conductive member  20  has a receiving groove  21 , which is opened at the front side (i.e., on the right side in  FIGS. 1(A) and 1(B) ) and extends in a front-and-back direction, so as to be able to insert a second conductive member  30  therein from the front side (i.e., the right side in the figures). The second conductive member will be described later. 
     In the first embodiment, the first conductive member  20  holds the electrical connecting members  10  at an upper inner surface and a lower inner surface of the receiving groove  21 , so that the electrical connecting members  10  face each other in the up-and-down direction so as not to come off therefrom. With the electrical connecting members  10  being mounted in the first conductive member  20  in this way, one unit  1  is formed. The configuration of the unit  1 , i.e., the shape of the first conductive member  20  and the arrangement of the electrical connecting member  1 , is symmetrical in an up-and-down direction. 
     In  FIGS. 1(A) and 1(B) , on each of the upper and lower inner surfaces of the first conductive member  20 , which face each other in the up-and-down direction, there are provided holding grooves  22  that laterally extends (i.e., in a width direction of the first conductive member  20 ). The holding grooves  22  are for holding the electrical connecting members  10 . Each of the holding grooves  22  has flange portions  23  formed on the opening side (the front side in the figure) and the bottom side (the rear side in the figure) of the receiving groove  21 . 
     In the first embodiment, the flange portions  23  restrict both side edges of each of the electrical connecting member  10  to be engage thereto, so as to keep the electrical connecting members  10  from coming off from the holding grooves  22 . In addition, on the first conductive member  20 , small-diameter holes  24  are formed so as to pierce from the outer upper and lower surfaces towards the receiving groove  21 . The small-diameter holes  24  are provided at position near the both side surfaces of the first conductive member  20  near ends of the flange portions  23 . Into the small-diameter holes, there are engaging pins  25  hammered from the outer upper and lower surfaces. 
     In the first embodiment, the engaging pins  25  protrude from a bottom of the holding groove  22 , and thereby can engage with the base portion of the electrical connecting members  10 , which will be described later. As a result, the electrical connecting members  10  are prevented from sliding off to sideway (i.e., in the width direction of the first conductive member) from the holding groove  22 . Accordingly, the electrical connecting members  10  are held in the respective upper and lower holding grooves  22  having the flange portions  23 , and the unit  1  is composed. 
     In the first conductive member  20 , inner surfaces  26  of the opening of the receiving groove  21  to receive the second conductive member  30  are slightly sloped. As a result, the groove width, which is a dimension formed (in the up-and-down direction in  FIG. 1(A) ) between inner surfaces of the opening of the receiving groove  21 , enlarges at the front (i.e., the opened side of the receiving groove  21 ). Moreover, at a rear end surface of the first conductive member  20 , there is provided a connecting pin  27  so as to protrude backward. The connecting pin  27  is for attaching to connect the first conductive member  20  onto a bus bar B. The bus bar B is provided on the side of a power source (not illustrated), which receives electric power from the power source. 
     Accordingly, the unit  1  is formed by holding the electrical connecting member  10  within the first conductive member  20 , to which the bus bar B is connected. Then, to the unit  1 , the second conductive member  30  is connected. According to the embodiment, the second conductive member  30  is formed as a strip-like flat member, which extends in the front-and-back direction in  FIG. 1(A) . The second conductive member  30  is formed as another bus bar that can be inserted to/pulled out from the receiving groove  21  of the first conductive member  20 . 
     In the first embodiment, the second conductive member  30  has a V-shaped end  31  with the tip (rear end) having some roundness. Inserting the V-shaped end  31  of the second conductive member  30  into the receiving groove  21  of the first conductive member  20 , the upper and lower electrical connecting members  10  and the top and bottom surfaces of the second conductive member  30  contact each other with certain contact pressure as shown in  FIG. 1(B) . 
     As a result the first conductive member  20  is connected to the second conductive member  30  via the electrical connecting members  10 . Accordingly, the bus bar B on the power-source side receives electric power from the power source. Then, the second conductive member  30  as another bus bar on the power-distribution side receives the electric power via the unit  1  (the first conductive member  20  and the two electrical connecting members  10 ). From the second conductive member  30 , the electric power will be distributed to specified device(s). 
       FIG. 2  is a top perspective view showing the electrical connecting member  10  according to the first embodiment of the present invention.  FIG. 3  is a side view showing the electrical connecting member  10  according to the first embodiment of the present invention. 
     As shown in  FIGS. 2 and 3 , the electrical connecting members  10  are configured by arranging to hold a plurality of contact pieces  16  with the holding member  11 .  FIGS. 2 and 3  show a part of the electrical connecting member  10  in a longitudinal direction X, which is an arrangement direction of the contact pieces  16 .  FIG. 2  is a top perspective view showing the state that a part of the contact pieces  16  is removed on the left end side.  FIG. 3  is the side view. Moreover, each of the electrical connecting members  10  is obtained by attaching the contact pieces  16  onto the holding member  11 . 
       FIGS. 4(A) and 4(B)  are bottom perspective views showing the electrical connecting member  10  according to the first embodiment of the present invention. More specifically,  FIG. 4(A)  is the bottom perspective view thereof before the contact piece  16  is attached to the holding member  11  of the electrical connecting member  10 , and  FIG. 4(B)  is the bottom perspective view thereof after the contact piece  16  is attached to the holding member  11  of the electrical connecting member  10 . The state before the attachment and the state after the attachment are shown in  FIGS. 4(A) and 4(B) , respectively. Here,  FIGS. 4(A) and 4(B)  are the view showing how to attach the connecting piece  16  onto the holding member  11 . For easy understanding,  FIGS. 4(A) and 4(B)  are provided in upside-down views of  FIGS. 2 and 3 . 
     In the first embodiment, the holding member  11  is made by punching relatively thin metal strip-like sheet, e.g. by presswork. As shown in  FIG. 2 , the holding member  11  includes two base portions  12  and a plurality of connecting portions  13 . The two base portions  12  extend in the longitudinal direction X of the holding member  11  and are parallel to each other. The plurality of connecting portions  13  is provided at constant intervals in the longitudinal direction X to join the two base portions  12 . Here, a joining direction (i.e., a width direction of the holding member  11 ) Y is set as a direction that the connecting portions  13  extend. 
     In the first embodiment, on each of the base portions  12 , there are provided holes  14  that serve as carriers. Those holes  14  are made by drilling so as to be aligned to positions of the connecting portions  13  in the longitudinal direction X. In order to fabricate the holding member  11  from strip-like sheet metal, a feeding and engaging claws (not illustrated) engage with the holes  14 , so as to feed/move the strip-like sheet metal intermittently. Once the feeding/moving of the sheet metal in the longitudinal direction X stops, a thin window  15  is formed between the adjacent holes  14 . Each of the windows  15  is formed so as to extend in a width direction of the strip-like sheet metal. As a result, the above-described connecting portions  13  are also formed. As described above, upon forming the connecting portions  13 , the holes  14  work as carriers to feed/move the strip-like sheet metal. 
     In the first embodiment, each of the connecting portions  13 , which joins the two base portions  12 , has a strip-like portion  13 A and a holding portion  13 B. The strip-like portions  13 A extend in the joining direction Y (i.e., the width direction of the holding member  11 ). Each of the holding portions  13 B is provided at a middle part of one side edge of the strip-like portion  13 A in the joining direction so as to be like a piece protruding therefrom. On each of the holding portions  13 B, there is provided a holding window  13 B- 1 , which is opened and is long in the joining direction (i.e., the width direction of the holding member  11 ). 
     In the first embodiment, each of the connecting portions  13  is twisted at a portion between the holding portion  13 B and the base portions  12 , and the holding portion  13 B becomes tilted for an angle of θ relative to the base portion  12 . Here, being different from the contact pieces  16 , which contribute to electrical connection, the holding members  11  can be made from a stainless steel-based material or the like, which is superior in workability and inexpensive. 
     Next, the contact pieces  16  are formed as flat pieces from thicker sheet metal than that of the holding member  11  using copper or copper alloy, which has superior conductivity. The contact pieces  16  have high rigidity and high conductivity. In each of the contact pieces  16 , an outer shape of a sheet surface thereof is a shape of a short arrow head. Each of the contact pieces  16  has a first plate portion  17  and a second plate portion  18  as a continuous one member. The first plate portion  17  forms a lower part of the contact piece  16  in  FIG. 2 , and has a laterally long rectangular shape. The second plate portion  18  forms an upper part relative to the first plate portion  17  and has a triangular shape. 
     As shown in  FIGS. 4(A) and 4(B) , a lower edge of the first plate portion  17  of the contact piece  16  forms a parallel edge, which extends being parallel to the connecting portions  13 , with the joining direction (i.e., extending direction) Y of the connecting portions  13  being a width direction of the contact pieces  16 . On the lower edge, there are provided two first contact portions  17 A. Those two first contact portions  17 A are formed as protrusions at positions near the both ends in the width direction. 
     On the other hand, the second plate portion  18  generally has a shape of isosceles triangle having two slanted edges  18 B to form a bottom side protruding more in the width direction than the width of the first plate portion  17 . At a vertex portion of the second plate portion  18 , there is formed a second contact portion  18 A. In each of the contact pieces  16 , the first contact portion  17 A, the second contact portion  18 A, and the slanted edge  18 B are formed to have some roundness in the width and sheet thickness directions of the contact piece  16 . 
     In the first embodiment, on each of the contact piece  16 , between the first contact portions  17 A and the second contact portion  18 A, there is provided a held portion  19 . The held portion  19  is to be held by the holding portion  13 B, which is formed to protrude from the connecting portion  13  of the holding member  11 . 
     According to the first embodiment, the held portion  19  is provided at a lower part of the second plate portion  18 , being close to the first plate portion  17 . As shown in  FIG. 4(A) , the held portion  19  is formed as a laterally long protruding portion on one sheet surface (which is shown as an upper surface in the view of  FIG. 4(A)  and a lower surface in the view of  FIG. 2 ) of the contact piece  16 . In  FIG. 4 , the held portion  19  is shown as a protruding portion on the one sheet surface of the contact piece  19 . In  FIGS. 2 and 3 , the held portion  19  is shown as a concave portion on the other sheet surface of the contact piece  16 . The held portion  19  and the corresponding holding portion  13 B of the holding member  11  can be provided at a plurality of positions instead of only at one position, and can be on the first plate portion  17 . 
     In the first embodiment, when the contact pieces  16  are attached onto the holding member  11  to be held thereby as shown in  FIGS. 4(A) and 4(B) , the electrical connecting member  10  can be obtained. 
     More specifically, forming the holding member  11  that is long in the arrangement direction of the contact pieces  16 , and then attaching the contact pieces onto the holding member  11 , the electrical connecting member  10  may be formed. Then, the long holding member  11  can be cut into necessary length(s) to use. 
     Hereunder, a method of producing the electrical connecting member  10  will be described in detail. 
     First, prepare the holding member  11  and the contact pieces  16 . In the holding member  11 , the connecting portions  13  thereof are already twisted in the range of the holding portions  13 B. 
     As shown in  FIG. 4(A) , bring the held portion  19  of one contact piece  16  under the holding portion  13 B (i.e., the holding portion provided at the lowest position in  FIG. 4(B) ). Then, press the held portion  19 , which is a protruding portion, into the holding window  13 B- 1  of the holding portion  13 B, such that the held portion  19  protrudes from the holding window  13 B- 1 . Thereafter, using a tool, swage the protruding part of the held portion so that the held portion can be securely held by the holding portion  13 B (See  FIG. 4(B) ). 
     As already described above, the connecting portions  13  are twisted in the range of the holding portions  13 B. Therefore, as shown in  FIG. 3 , the contact pieces  16  held by the holding portions  13 B are held, while being tilted for the twisted angle θ from the surface of the base portions  12 . In  FIG. 2 , the contact pieces  16  are held such that the second contact portions  18 A, vertex parts of the slanted edges  18 B, are directed upward relative to the holding member  11 . 
     On the other hand, in  FIG. 4(B) , which is the bottom perspective view, the second contact portion  18 A is directed downward relative to the holding member  11 . Similarly, the rest of the contact pieces  16  is successively attached to be held onto the holding member  11  as described above and the electrical connecting member  10  can be completed. At this time, the holding member  11  is moved/fed stepwise to the holes  14 , and then stopped at the holes  14  being caught by the engaging claws. The holes work as carriers. 
     As described above, the held portions  19  of the contact pieces  16  are attached to the holding portions  13 B of the holding member  11 . As a result, the contact pieces  16  are held by the holding member  11 . Thereafter, the holding member  11  is to be cut at the base portions  11  to a length suitable for the first conductive member  20 . 
     Accordingly, the plurality of the contact pieces  16  is arranged and held by the electrical connecting member  10 . As shown in  FIGS. 1(A) and 1(B) , while orientating the electrical connecting member  10  such that the second contact portions  18 A direct inward of the holding groove  22  of the first conductive member  20 , the base portions  12  of the holding member  11  are inserted in place in the first conductive member from one side of the holding groove  22  (i.e., one of the side surfaces of the first conductive member  20  that face each other in the first conductive member&#39;s width direction), so as to be supported by inside of the flange portion  23 . 
     Then, engaging pins are hammered into the small-diameter holes  24  of the first conductive member  20 . Tips of the engaging pins  25  protrude towards the holding grooves  23  at positions very close to the ends of the holding member  11  (i.e., the ends of the holding member  11  in the width direction of the first conductive member  20 ). As a result, the electrical connecting member  10  is held by the first conductive member  20  and will not come off from any of the two sides of the first conductive member  10 . 
     As described above, the electrical connecting member  10  is mounted in each of the holding grooves provided on the upper and lower inner surfaces of the first conductive member  20 . As a result, the first contact portions  17  of the both electrical connecting members  10  face each other in the up-and-down direction. The interval “a” between the first contact portions  17 A in the up-and-down direction is set smaller than a thickness “d” of the second conductive member  30 . 
     As described above, according to the first embodiment, the unit  1  is provided in the form of an electrical connector, in which the electrical connecting members  10  having the above-described configuration are mounted in the first conductive member  20 . The electrical connector having the unit  1  and the second conductive member  30  may be used as follows. 
     First, the connecting pins  27  provided on the rear end surface of the first conductive member  20  of the unit  1  is placed to attach in the corresponding holes (not illustrated), so as to attach the first conductive member  20  onto the bus bar B provided on the power-source side. Then, contacting the rear end surface of the first conductive member  20  to the bus bar B by surface, the first conductive member  20  and the bus bar B are electrically connected. Here, the bus bar B is electrically connected, and supplies electrical power to the first conductive member  20 . 
     Thereafter, the second conductive member  30 , which is formed as a flat strip, is mounted in the unit  1 . The second conductive member  30  serves as another bus bar provided on the power-distribution side. The second conductive member  30  is inserted to between the upper and lower electrical connecting members  10 , which are held in the first conductive member  20 . At this point, as shown in  FIG. 1(B) , the second conductive member  30  pushes the both electrical connecting members  10  so as to move the second contact portions  18 A of the contact pieces  16  away from each other in the up-and-down direction. 
     As shown in  FIG. 3 , since the second contact portions  18 A of the contact pieces  16  receive pressing force P from the second conductive member  30 , the first contact portions  17 A of the contact pieces  20  receive reaction force Q from the first conductive member  20 . With the pressing force P and the reaction force Q, moment M occurs on the contact pieces  16 . As a result, in each of the electrical connecting member  10 , the contact pieces  16  cause elastic twisting displacements of the connecting portions  13  via the holding members  13 B, so as to allow decrease of the tilting angle θ in the holding posture of the contact pieces  16 . 
     As described above, the respective contact pieces  16  of the electrical connecting members  10  electrically connect to the second conductive member  30  and the first conductive member  20 , having the pressing force P and the reaction force Q as contact pressures, so as to transmit electric power. In the both electrical connecting members  10 , the plurality of contact pieces  16  can independently change the tilting angle θ. 
     Therefore, all of the contact pieces  16  can surely contact with the second conductive member  30 . Each of the contact pieces  16  has some roundness on the first contact portion  17 A, the second contact portion  18 A, and the slanted edges  18 B in the joining direction (i.e., extending direction) of the connecting portions  13  and the sheet thickness direction thereof (i.e., the up-and-down direction in  FIG. 1(A) ). Therefore, when the second conductive member  30  is inserted to mount in the unit  1  and when the tilting angles θ of the contact pieces  16  change, the contact surfaces of the first conductive member  20  and the second conductive member  30  will not be damaged. 
     According to the first embodiment, the holding member  11  can be modified, altered, or changed.  FIG. 5  is a top perspective view showing a modified example of the electrical connecting member  10  according to the first embodiment of the present invention. 
     As shown in  FIG. 5 , forming the joining direction (i.e., extending direction) Y of the joining members  13  to have an angle φ from the base portions  12 , it is achievable to make the length of the joining members  13  greater than that of the interval of the two base portions  12 . Furthermore, the elastic twisting displace can be easily generated, and it is achievable to securely avoid influence of the twisting on the base portions  12 . 
     Second Embodiment 
     A second embodiment of the present invention will be explained next. According to the first embodiment shown in  FIGS. 2 through 5 , the held portions  19  are formed as laterally long protrusions (i.e., which are to be long in the extending direction of the joining member), and there are laterally long holding windows  13 B- 1  on the holding portions  13 B, to receive the held portions  19 . 
       FIGS. 6(A) and 6(B)  are bottom perspective views showing an electrical connecting member according to the second embodiment of the present invention. More specifically,  FIG. 6(A)  is the bottom perspective view thereof before the contact piece  16  is attached to the holding member  11  of the electrical connecting member and  FIG. 6(B)  is the bottom perspective view after the contact piece  16  is attached to the holding member  11  of the electrical connecting member. 
     According to the second embodiment, as shown in  FIGS. 6(A) and 6(B) , the held portions  19  are provided as short cylindrical protrusions provided at two positions that are away from each other in the lateral (joining) direction. Each of the holding portions  13 B has holding windows that are formed as circular holes to receive the held portions  19 . With this configuration, it is achievable to securely hold each of the contact pieces  16  at two positions, which are away from each other, while the held portions  19  and the holding portions  13 B can have relatively simple shapes. 
     Third Embodiment 
     A third embodiment of the present invention will be explained next. According to the embodiments of  FIGS. 1 through 6 , in each of the contact pieces  16 , the second plate portion of has a generally triangular shape. Alternatively, each of the contact pieces can have a generally a trapezoidal shape instead of the triangular shape. 
       FIGS. 7(A) and 7(B)  are top perspective views showing an electrical connecting member according to the third embodiment of the present invention. More specifically,  FIG. 7(A)  is the top perspective view thereof before the contact piece  16  is attached to the holding member  11  of the electrical connecting member and  FIG. 7(B)  is the top perspective view after the contact piece  16  is attached to the holding member  11  of the electrical connecting member. 
     According to the third embodiment, the second plate portion of the contact piece has a generally trapezoidal shape as shown in  FIGS. 7(A) and 7(B) . Here, in  FIGS. 7(A)  and  7 (B), common parts with the embodiments of  FIGS. 1 through 6  are referenced with the same reference numerals and explanation of those common parts is omitted. 
     As shown in  FIG. 7(A) , according to the third embodiment, in each of the contact piece  16 , the second plate portion  18  has a generally trapezoidal shape. The top part of the second plate portion  18  is formed as an edge parallel to the width direction, which is to be a joining direction (i.e., the extending direction) of the connecting portion  13 , and forms a second contact portion  18 A. Each of the second contact portion  18 A extends long in the width direction. 
     As a result, it is achievable to secure large contact area between the second contact portion  18 A and the second conductive member  30  to flow large current. On the both ends of each of the second contact portion  18 A in the width direction, a slanted edge  18 B respectively extends therefrom. According to the third embodiment, in each of the contact piece  16 , in addition to having the slanted edge  18 B as an upper edge, lower edges  18 C of the second plate portion  18  (i.e., the bottom edge parts of the trapezoidal part) are slanted downward towards the middle part of the bottom part of the trapezoidal part in the width direction of the contact piece  16 , while the lower edges  18 C are not slanted in the first and the second embodiments. With this configuration, it is achievable to enhance the strength at a boundary region between the second plate portion  18  and the first plate portion  17 . 
     In the third embodiment, each of the second plate portions  18  has a held portion  19  near the first plate portion  19  in a middle part thereof in the width direction. The held portion  19  includes a washer-like portion  19 B and held protrusions  19 A. In each contact piece  16 , the held portion  19  is formed to have the protrusions  19 A by embossing so as to protrude from one sheet surface of the contact piece  16  being pressed from the other sheet surface as shown in  FIG. 7(A) ). 
     In the third embodiment, the protruding held protrusions  19 A are provided in two being next to each other in the width direction of the contact piece  16 . In the range that includes the two held protrusions  19 A, the washer-like portion  19 B is formed, extending long in the width direction and protruding from the one sheet surface of the contact piece  16 . The held protrusions  19 A protrude from the washer-like portion  19 B. 
     As described above, the held protrusions  19 A and the washer-like portion  19 B are formed by embossing to protrude from the surface of the contact piece  16  as shown  FIG. 7(A) . As shown in the top perspective view,  FIG. 8(B) , which is an upside-down view of  FIG. 7(A) , on the other sheet surface of the contact piece  16 , a corresponding area to the held protrusions  19 A and the washer-like portion  19 B are dented to the side of the one sheet surface by the embossing. 
     In the third embodiment, the first plate portion  17  extends downward (slightly leftward in the view of  FIG. 7(A) ) from a lower edge of the second plate portion  18 . The first plate portion  17  has two legs  17 B, which are provided at a certain interval therebetween and extend downward. On the front side of the contact piece  16 , which is shown in  FIG. 7(A) , lower ends of the legs  17 B are relatively rounded being bent in the sheet thickness direction. 
     In the third embodiment, the lower ends are formed as first contact portions  17 A, extending straight in the width direction of the contact piece  16 . Since the first contact portions  17 A extend long, it is achievable to secure large contact area to contact with the first conductive member  20  at the first contact portions  17 A, and thereby achievable to flow large current. 
     As shown in  FIG. 8(B) , the other sheet surface (i.e., backside) of the second plate portion  18  is dented by the embossing of the holding protrusions  19 A and the washer-like portion  19 B. In addition, in a lower part of a backside of each leg  17 B, there is formed a concave portion  17 B- 1  by presswork so as to reduce the thickness outside the washer-like portion in the width direction of the contact piece  16 . 
     Once the contact pieces  16  receive pressing force from the first conductive member  20  to contact thereto, the contact pieces  16  tilt so as to reduce the angle θ (see  FIG. 3 ) with the connecting portions  13  being fulcrums. In other words, the plurality of contact pieces  16  become close to each other. At this time, in each contact piece  16 , the legs  17 B having the first contact portions  17 A become close to the adjacent connecting portion(s)  13  that hold other contact piece(s)  16 . 
     In the third embodiment, on the connecting portions  13 , elastic twist occurs so as to reduce the tilting angle θ. Since the elastic twist accompanies warping of the connecting portions  13 , the concave portions  17 B- 1  formed on the backside of the legs  17 B displace by the warping. The displacement is greater on the outside of the legs  17 B than the inside of the legs in the width direction. The displacement of the concave portions  17 B- 1  contributes to avoid interference with backside of the legs  17 B. 
     In the third embodiment, on the other hand, in the example of  FIGS. 4(A) and 4(B)  or  FIG. 5 , in each of the holding member  11  to hold the contact pieces  16 , the holding windows  13 B- 1  are provided on the holding portions  13 B on strip-like portions  13 A of the connecting portions  13 . 
     According to the third embodiment, each of the connecting portions  13  has only strip-like portion and the protruding portion is not provided. Each connecting portion  13 , which forms the strip-like part, has holding windows  13 B- 1 , which are circular holes. 
     According to the third embodiment, the contact pieces  16  are to be attached and held onto each of the holding members  11 . 
     First, as shown in  FIG. 7(A) , insert the first plate portion  17  of each of the contact pieces  16  into one of windows  15  of the holding member  11 , such that the contact piece  16  comes under the connecting portion  13 . 
     Next, position the held protrusions  19 A to fit to the holding windows  13 B under the holding member  13 . As described above, the held protrusions  19 A are formed to protrude from each of the contact piece  16 . Then, completely press the protruding held portions  19 A into the holding windows  13 B- 1  from there (i.e., under the holding member  13 ). At this point, the protruding held portions  19 A protrude from a surface (upper surface) of the connecting portion  13 . Similarly to the case of the previously described embodiments, swage the protruding held portions  19 A with a tool, so as to have the contact piece  16  be held by the connecting portion  13  (see  FIG. 7(B) ). The contact pieces  16  may be successively attached one by one on the holding member  11  as described above. 
     According to the first embodiment shown in  FIGS. 4(A) and 4(B)  and the second embodiment shown in  FIGS. 6(A) and 6(B) , each of the contact pieces  16  is attached in the order of from the lower joining member  13  to the upper joining member  13 . On the other hand, according to the third embodiment, the protruding held portions  19 A are provided on the contact pieces  16 , being lower than those of the first and the second embodiment. Therefore, being opposite the case of the first and the second embodiment, according to the third embodiment, the contact pieces  16  are attached on the holding member  11  in the order of from the upper joining member  13  to the lower joining member  13 . 
       FIGS. 8(A) and 8(B)  show a state that the plurality of the contact pieces  16  is attached to the holding member  11  in the manner described above ( FIG. 8(A)  is the view showing the front surfaces of the contact pieces  16  and  FIG. 8(B)  is the view showing the back surfaces of the contact pieces  16 ). 
     Fourth Embodiment 
     A fourth embodiment of the present invention will be explained next.  FIG. 9  is a perspective view showing a unit including the electrical connecting member  10  according to the fourth embodiment of the present invention. 
     According to the fourth embodiment, the first conductive member  20  is formed by joining an upper and lower conductive members  20 A and  20 B with coupling bolts  28 . The first conductive member  20  has an opening on the left and the right sides, which respectively form receiving grooves  21 . 
     In the fourth embodiment shown in  FIG. 9 , the power source-side bus bar B is inserted in the left receiving groove  21 . In the right receiving groove, the second conductive member  30 , which serves as a power distribution-side bus bar, is inserted. In addition, the second conductive member  30  is coupled to the first conductive member  20  with the engaging pins  29  so as not to be pulled out therefrom. 
     According to the first through the fourth embodiments shown in  FIGS. 1(A) and 1(B)  through  9 , a flat connector is composed of the first conductive member  20 , the electrical connecting members  10 , and the second conductive member  30 . According to the present invention, it is also achievable to form a cylindrical connector. 
     Fifth Embodiment 
     A fifth embodiment of the present invention will be explained next.  FIG. 10  is a perspective view showing the electrical connecting member  10 , the first conductive member  20 , and the second conductive member  30  according to the fifth embodiment of the present invention. 
     According to the fifth embodiment, the first conductive member  20  has a cylindrical shape, and the second conductive member  30  has a cylindrical shape. The electrical connecting member  10  is made by forming the holding member  13 B by punching thin sheet metal. Therefore, only two thin strip-like base portions  12  continuously extend along the longitudinal direction. As a result, it is easy to flex in the sheet thickness direction to form the cylindrical shape. 
     According to the fifth embodiment, curving the base portions into a cylindrical shape, the electrical connecting member  10  can be accommodated by winding around into the holding grooves formed on an outer circumferential surface of the first conductive member  20 . At this point, it is necessary to keep the holding member  11  not to be opened up from the wound state, by keeping the coupling ends of the base portions  12  coupled in the circumferential direction. Accordingly, the electrical connecting member  10  is wound and held around the first conductive member  20 , which forms one unit  1 . When the second conductive member  30  with a cylindrical shape is fitted into the unit  1 , a cylindrical connector is formed. 
     The disclosure of Japanese Patent Applications No. 2016-131387, filed on Jul. 1, 2016, and No. 2015-188894, filed on Sep. 25, 2015, are incorporated in the application by reference. 
     While the present invention has been explained with reference to the specific embodiments of the present invention, the explanation is illustrative and the present invention is limited only by the appended claims.