Abstract:
An electrical connection device is to be attached to a wiring board for holding a plate conductive member so that the wiring board is electrically connected to the plate conductive member. The electrical connection device includes a contact piece including an arm portion, a leg portion, and a base portion disposed between the arm portion and the leg portion; and a base member to be attached to the wiring board for supporting the contact piece at the base portion thereof. The base member is to be attached to the wiring board so that the base member is movable in parallel to the wiring board. The contact piece is arranged so that the plate conductive member pushes the arm portion to urge the leg portion against the wiring board with the base portion as a pivot when the plate conductive member contacts with the arm portion.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
     The present invention relates to an electrical connection device for connecting a busbar so that a large electrical current flows. More particularly, the invention relates to an electrical connection device for electrically connecting a wiring board with a plate conductive member. 
     Patent Reference has disclosed a conventional electrical connection device.  FIG. 7  shows an example of a conventional electrical connection device 130 disclosed in Patent Reference. 
     Patent Reference: U.S. Pat. No. 5,431,576 
     According to Patent Reference, the conventional electrical connection device 130 includes contact sides 152 and 154 that have the same shape and are disposed to face each other. An opening 134 is formed between the contact sides 152 and 154, so that a plate connector (conductive member) 128 is inserted through the opening 134 to be secured on a substrate 109. 
     The conventional electrical connection device 130 is to be mounted on a back plate 112 with common fixing screws. With the fixing screws 162, the conventional electrical connection device 130 is completely fixed on the back plate 112. 
     According to the conventional electrical connection device 130, when the plate conductive member (connector) 128 is inserted in the conventional electrical connection device 130 through the opening 134 formed between the contact side 152 and the contact side 154, misalignment may occur between the plate conductive member 128 and the opening 134 of the electrical connection device 130 depending on an entering direction and/or position of the plate conductive member 128 relative to the opening 134. When the plate conductive member 128 is misaligned relative to the opening 134 of the electrical connection device 130, for example, undesired force may be generated near the fixing portion between the conventional electrical connection device 130 and the back plate 112, thereby making the large-current connection of the contact sides 152 and 154 with the back plate 112 and the plate conductive member unstable. 
     According to the conventional electrical connection device 130 disclosed in Patent reference, the misalignment between the plate conductive member 128 and the opening 134 of the electrical connection device 130 is accommodated by resilience of the contact bands 180, or by providing a clamping body 160 having a fold 174 inside the opening 134 of the electrical contacting device 130 so as to securely contact with the plate conductive member 128 from any directions. 
     However, when the misalignment is significant, or when high contact precision is required between the plate conductive member 128 and the clamping body 160, such accommodating means is not enough to accommodate the misalignment. 
     In view of the problems described above, an object of the present invention is to provide an electrical connection device that can securely electrically connect contact sides with a back plate and a plate conductive member, while accommodating misalignment between the plate conductive member and an opening of the electrical connection device. 
     Further objects and advantages of the present invention will be apparent from the following description of the present invention. 
     SUMMARY OF THE PRESENT INVENTION 
     In order to attain the objects described above, according to a first aspect of the present invention, an electrical connection device is for holding a plate conductive member upright on a planar surface of a wiring board and electrically connecting the plate conductive member with the wiring board. The electrical connection device includes a contact piece, and a base member for supporting the contact piece at a base portion provided between an arm portion and a leg portion of the contact piece. The electrical connection device is provided so as to be able to float on the planar surface of the wiring board. When the arm portion of the contact piece contacts with one planar surface of the plate conductive member, the arm portion is urged toward a side of the planar surface of the wiring board through the contact, and in response to this, the leg portion is urged to the side of the wiring board having the base portion as a fulcrum. 
     According to the first aspect of the invention, when the plate conductive member is held with the electrical connection device, the leg portion of the contact piece is urged to a side of the wiring board. Therefore, it is possible to push the leg portion of the contact piece toward the wiring board and thereby to enhance the contact between the leg portion and the wiring board. As a result, it is achievable to obtain secure electrical connection of the contact piece with the wiring board and the plate conductive member. In addition, when the plate conductive member is held with the electrical connection device, the leg portion of the contact piece also contacts with the wiring board with certain force. Therefore, it is achievable to stably hold the plate conductive member with the electrical connection device. 
     On the other hand, in a state before the plate conductive member is held with the electrical conductive member, the contact piece is attached to the base member with some space around the base portion. As a result, it is possible to have a certain play and to accommodate misalignment of the plate conductive member relative to the electrical connection device upon receiving the plate conductive member to the electrical connection device. Furthermore, when a floating movement is possible between the electrical connection device and the wiring board, it is also possible to easily accommodate misalignment of the plate conductive member relative to the electrical connection device upon receiving the plate conductive member to the electrical connection device. 
     According to a second aspect of the invention, in the electrical connection device, the arm portion of the contact piece extends along one planar surface of the plate conductive member, and the leg portion of the contact piece extends along the planar surface of the wiring board. The arm portion of the contact piece has a contact point so as to protrude toward the plate conductive member when the plate conductive member is held with the electrical connection device. With the contact point, an insertion opening is formed for inserting the plate conductive member therein. The insertion hole has preferably a size smaller than a thickness of the plate conductive member. 
     According the second aspect of the invention, when the insertion opening has the size smaller than the thickness of the plate conductive member, the arm portion of the contact piece certainly contacts with the one planar surface of the plate conductive member upon inserting the plate conductive member in the insertion opening. Therefore, with the leverage principle, the contact force occurred between the plate conductive member and the contact piece is to be certainly transmitted to the contact point of the leg portion. 
     According to a third aspect of the invention, in the electrical connection device, the contact piece is composed of a set of a first contact piece and a second contact piece. The first contact piece has a first arm portion having a first contact point and the second contact piece has a second arm portion having a second contact point. Between the first contact point and the second contact point, an insertion opening is formed for inserting the plate conductive member therein. When the first arm portion of the first contact piece contacts with the one planar surface of the plate conductive member, the first contact piece is urged to a side of the planar surface of the wiring board through the contact. In response, the first leg portion of the first contact piece is urged to a side of a planar surface of the wiring board, with the base portion serves as a fulcrum. When the second arm portion of the second contact piece contacts with the other planar surface of the plate conductive member, the second contact piece is urged to a side of the planar surface of the wiring board through the contact. In response, the second leg portion of the second contact piece is urged to a side of the wiring board, with the second base portion serves as a fulcrum. 
     According to the third aspect of the present invention, the plate conductive member is inserted in the electrical connection device through the insertion opening formed between the arm portion of the first contact piece and the arm portion of the second contact piece. When the plate conductive member is inserted in the electrical connection device, both the first contact piece and the second contact piece can contact with the both planar surfaces of the plate conductive member at the same time, thereby making it possible to evenly apply a force to the plate conductive member. 
     According to a fourth aspect of the invention, in the electrical connection device, preferably, there is provided a pressing member between the first base portion of the first contact piece and the second base portion of the second contact piece. With the pressing member, it is achievable to prevent the first contact piece and the second contact piece from coming off from a support member. 
     According to a fifth aspect of the invention, in the electrical connection device, the base member has an engaging protrusion or an engaging recess, and the pressing member has an engaging recess or an engaging protrusion at an opposing position to that of the engaging protrusion or the engaging recess of the base member. With the configuration, when the engaging protrusion of the base member or the engaging protrusion of the pressing member respectively penetrates through the first engaging hole of the first contact piece and the second engaging hole of the second contact piece, it is possible to place the engaging protrusion of the base member or the engaging protrusion of the pressing member in the engaging recess of the base member or the engaging recess of the pressing member. 
     According to the fifth aspect of the present invention, with a simple configuration, it is possible to rotatably support the first contact piece and the second contact piece between the one planar surface or the other planar surface of the plate conductive member and the wiring board. 
     According to a sixth aspect of the invention, the first contact piece and the second contact piece respectively may have certain widths. In addition, the first engaging hole of the first contact piece and the second engaging hole of the second contact piece may be enlarged in a width direction thereof. 
     When the engaging holes have the certain width, the support member can more stably support the first contact piece and the second contact piece. 
     According to a seventh aspect of the invention, the electrical connection device preferably includes a resin cover, which covers at least a part of outsides of the first contact piece and the second contact piece. With the resin cover, it is achievable to prevent the contact pieces from breaking, and protect a user thereof from electrical shock. 
     According to an eighth aspect of the invention, in the electrical connection device, the support member is preferably made of a metal material. When the support member is formed of the metal material, it is achievable to increase durability of the support member against the contact piece, and electrically connect the contact piece with the wiring board through the support member. In addition, it is also achievable to further reinforce the contact between the contact piece and the wiring board. 
     According to the invention, it is possible to provide the electrical connection device that stabilizes contact of the contact piece of the electrical connection device with the back plate and the plate conductive member, while accommodating misalignment upon receiving the plate conductive member in the electrical connection device on the back plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an electrical connection device in use according to an embodiment of the present invention; 
         FIG. 2  is an exploded perspective view showing the electrical connection device according to the embodiment of the present invention; 
         FIG. 3  is a perspective partial sectional view showing the electrical connection device shown in  FIG. 1 , taken along a lateral direction thereof, according to the embodiment of the present invention; 
         FIG. 4  is a perspective partial sectional view showing the electrical connection device shown in  FIG. 1 , taken along a lateral direction thereof, according to the embodiment of the present invention; 
         FIG. 5  is a partial sectional view showing the electrical connection device shown in  FIG. 1 , taken along the lateral direction thereof, according to the embodiment of the present invention, wherein the electrical connection device is in a state before connecting a busbar to contact pieces; 
         FIG. 6  is a partial sectional view showing the electrical connection device shown in  FIG. 1 , taken along the lateral direction thereof, according to the embodiment of the present invention, wherein the electrical connection device is in a state after connecting the busbar to the contact pieces; and 
         FIG. 7  is a sectional view showing an example of a conventional electrical connection device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereunder, embodiments of the present invention will be described with reference to the accompanying drawings. 
       FIG. 1  is a perspective view showing an electrical connection device  1  in use according to an embodiment of the present invention, and  FIG. 2  is an exploded perspective view showing the electrical connection device  1  according to the embodiment of the present invention, respectively. 
     As shown in  FIG. 1 , the electrical connection device  1  is used in a state of being attached on a planar surface  4  of a wiring board  3 , which is a main busbar. According to the electrical connection device  1 , for example, a plate conductive member such as a busbar  5 , which is a sub busbar, is moved down or up in a direction indicated with an arrow “a”, so as to be attached to or removed from the electrical connection device  1 . When the busbar  5  is inserted to the electrical connection device  1 , the busbar  5  is held upright with the electrical connection device  1  on the planar surface  4  of the wiring board  3 , so that the busbar  5  is electrically connected to the wiring board  3 . 
     In the embodiment, the electrical connection device  1  generally has a laterally symmetrical shape as a whole. As well shown in  FIG. 2 , the electrical connection device  1  includes contact pieces  20 , a base member  60 , a pressing member  50 , a cover  40 , and shoulder screws  80 . The base member  60  supports the contact pieces  20 . The pressing member  50  prevents the contact pieces  20  from coming off from the base member  60  in cooperation with the base member  60 . The cover  40  covers outsides of the contact pieces  20 . The shoulder screws  80  are for mounting the electrical connection device  1  on the wiring board  3 . Here, among those members, essential members for the electrical connection device  1  are the contact pieces  20  and the base member  60 , and members other than those may be omitted. 
     Referring also to  FIGS. 3 through 6 , a configuration of the electrical connection device  1  will be fully described.  FIGS. 3 and 4  are perspective partial sectional views showing the electrical connection device  1 , taken along lateral directions of  FIG. 1 , but taken at different cross-sections from each other.  FIGS. 5 and 6  are partial sectional views, taken along lateral directions of  FIG. 1 . More specifically,  FIG. 5  shows a state before connecting the busbar  5  to contact pieces  20 , and  FIG. 6  shows a state the busbar  5  is held upright by the electrical connection device  1 . 
     In the embodiment, the contact pieces  20  are one of the essential members of the electrical connection device  1 . The contact pieces  20  are composed of a set of a contact piece  20 A and a contact piece  20 B, which have the same shape and are disposed to face each other. Upon holding the busbar  5  with the electrical connection device  1 , the busbar  5  is inserted in an insertion opening formed by the contact pieces  20 A and  20 B. Hereunder, as necessary, reference numerals of members related to the contact piece  20 A is affixed with “A” and those of members related to the contact piece  20 B are affixed with “B”, respectively. Here, when it is not necessary to distinguish between them, those letters may be omitted. 
     In the embodiment, the contact pieces  20  are formed from one thin sheet metal having a certain width by stamping and bending. Since the contact pieces are formed from sheet metal, the contact pieces  20  have good durability as well as good elastic action. In addition, since the contact pieces  20  can be easily made by stamping and bending, it is achievable to produce the contact pieces  20  inexpensively. The contact piece  20 A includes an arm portion  32 A extending along one planar surface  5 A of the busbar  5 , a leg portion  33 A extending along a planar surface  4  of the wiring board  3 , and a base portion  31 A provided between the arm portion  32 A and the leg portion  33 A. 
     In the embodiment, the contact piece  20 A has a generally L-shape as a whole, when viewed from a side thereof. Similarly, the contact piece  20 B includes an arm portion  32 B extending along the other planar surface  5 B of the busbar  5 , a leg portion  33 B extending along the planar surface  4  of the wiring board  3 , and a base portion  31 B provided between the arm portion  32 B and the leg portion  33 B. The contact piece  20 B has a generally L-shape as a whole, when viewed from a side thereof. The arm portions  32 A and  32 B are portions mainly used for contacting with the busbar  5 . The leg portions  33 A and  33 B are portions mainly used for contacting with the wiring board  3 . The base portions  31 A and  31 B are portions to be fulcrums for motion of the contact pieces  20 . 
     Each arm portion  32  includes a frame-like contact section  21  and a plurality of strip-like contact sections  22 . The frame-like contact section  21  is a portion that has a square-bottomed U-shape, from the base portion  31  toward a portion to contact with the busbar  5 . The frame-like contact portion  21  is provided to improve action of the strip-like contact portions  22 . 
     On the other hand, the strip-like contact sections  22  are portions provided to be like cantilevers from each base portion  31  toward the side for contacting with the busbar  5 , while being surrounded by the respective frame-like contact portions  21 . The strip-like contact portions  22  are provided mainly for obtaining electrical connection. The plurality of the strip-like contact sections  22  has the same strip-like shape and is arranged at the equal pitch from each other along a width direction of each contact piece  20 . 
     Each frame-like contact portion  21  and the strip-like contact portions  22  thereof respectively have contact points  21 ′ and  22 ′, which are bent so as to protrude toward a side for contacting with the busbar  5 . As well shown in  FIGS. 5 and 6 , the positions of the contact point  21 ′ of the frame-like contact portion  21  and the positions  22 ′ of the strip-like contact portions  22  are somewhat misaligned from each other in a direction of the arrow “a”, an insertion/removal direction of the busbar  5 . 
     When the busbar  5  is inserted in an insertion opening  34  between the contact piece  20 A and the contact piece  20 B, the busbar  5  first contacts with the contact points  21 ′ of the frame-like contact portions  21 . Then, the busbar  5  contacts with the contact points  22 ′ of the strip-like contact portions  22 . Accordingly, with the configuration, when the busbar  5  contacts with the contact points  21 ′ of the frame-like contact portions  21  before contacting with the contact points  22 ′ of the strip-like contact portions  22 , it is achievable to blow off arc, which causes increase of electrical contact resistance, by the frame-like contact portions  21 , and thereby prevent deterioration of the strip-like contact portions  22 . 
     In order to make contact with the wiring board  3  easier, the leg portions  33  also have contact points  33 ′ similarly to the arm portions  32 . The contact points  33 ′ of the leg portions  33  are formed by bending so as to protrude toward the side for contacting with the planar surface  4  of the wiring board  3 . As well shown in  FIG. 6 , the contact points  33 ′ can elastically contact with the planar surface  4  at least upon inserting the busbar  5  between the contact piece  20 A and the contact piece  20 B to hold the busbar  5  by the electrical connection device  1 . 
     In the embodiment, the base portions  31  support the contact pieces  20 , and serve as fulcrums in movements of the contact pieces  20 . In order to securely support the contact pieces  20 , there are engaging holes  27 A and  27 B near the center of the base portion  31  in the width direction thereof. Using those engaging holes  27 A and  27 B, it is achievable to prevent the contact pieces  20  from coming off from the base member  60 . Here, those engaging holes  27 A and  27 B can be enlarged in width directions thereof corresponding to the wide contact pieces  20 . With the engaging holes  27 A and  27 B having certain widths, it is achievable to prevent the contact pieces  20 A and  20 B from coming off in more stable state. 
     In the embodiment, the base member  60  is an essential member of the electrical connection device  1 , similarly to the contact pieces  20 . The base member  60  prevents the contact pieces  20  from coming off from the base member  60  in cooperation with the pressing member  50 , and serves as a fulcrum upon movement of the contact pieces  20 . The base member  60  is made of metal, and has generally a planar shape as a whole. Since it is made of metal, for example, it is achievable to increase the durability against the contact pieces  20 , and electrically connect between the contact pieces  20  and the wiring board  3  via the base member  60 . Furthermore, it is also achievable to further reinforce the contact between the contact pieces  20  and the wiring board  3 . 
     On each lateral edge of the base member  60 , there is provided a lifting portion  62 , which is formed by bending the edge downward. With the lifting portions  62 , it is achievable to keep the base member  60  away from the planar surface  4  of the wiring board  3  and form space between the base member  60  and the wiring board  3  so as to displace and accommodate the leg portions  33  of the contact pieces  20 . 
     Since the base member  60  also has a laterally symmetrical shape similar to other members, in order to distinguish between left portions and right portions thereof, a letter “A” or “B” is affixed after the reference numerals as necessary. Here, when it is not necessary to identify if it is a left portion or a right portion, those letters are omitted. 
     In the center of the base member  60 , there is provided a generally rectangular insertion hole, to which the contact pieces  20  can be inserted  20 . Furthermore, on the respective left and right edges of the insertion through holes  65 , there are three upright portions  68 ,  70 , and  75  along the insertion direction. At an end part  67  of each upright portion  68  provided in the center, there is formed an engaging protrusion  67  by bending for about 90 degrees toward the side of the insertion through hole  65 . The engaging protrusions  67  are provided corresponding to the engaging holes  27  provided on the base portions  31  of the contact pieces  20 . 
     Since the engaging protrusions  67  are relatively loosely fitted in the engaging hole  27  upon assembling of the electrical connection device  1 , the engaging protrusions  67  can support the contact pieces  20  while enabling the contact pieces to make some displacement. Here, since the contact pieces  20  are relatively loosely attached on the base portion  31 , at the time of being in a state before holding the busbar  5  with the electrical connection device  1 , it is possible to cause certain displacement in the contact pieces  20 . Therefore, it is achievable to accept physical displacement of the busbar  5 , a plate conductive member, relative to the electrical connection device  1  when the electrical connection device  1  receives the busbar  5 . 
     In the embodiment, the upright portions  70  and  75  are respectively disposed at positions so as to interpose the upright portion  68  in between. On the side of the insertion through hole  65 , the upright portions  70  and  75  respectively form abutting surfaces  71  and  76  that abut against planar surfaces of the base portions  31  of the contact pieces  20 . By leverage action, the contact pieces  20  can move, using the contacting parts thereof, which contact with the abutting surfaces  71  and  76 , as fulcrums. The end parts  73  and  77  of the upright portions  70  and  75  are bent for generally 90 degrees toward the side opposite the end parts  67  of the upright portions  68 , i.e., on the side opposite the insertion through hole  65 . By forming the bent portions, the end parts  73  and  77  of the upright portions  70  and  75  will not interfere with the movements of the contact pieces  20 . 
     In the embodiment, the pressing member  50  is provided between the base portion  31 A of the contact piece  20 A and the base portion  31 B of the contact piece  20 B. The pressing member  50  has engaging recesses  52  so as to fit to the engaging protrusions  67  of the base member  60 . While the engaging protrusions  67  of the base member  60  penetrates the engaging holes  27  of the contact pieces  20 , the engaging protrusions  67  are fitted in the engaging recesses  52  of the pressing member  50 . As a result, it is achievable to avoid interference with the pressing member  50  and the engaging protrusion  67  and to prevent the contact piece  20 A and the contact piece  20 B from coming off from the insertion through hole  65  with a simple configuration. 
     Here, being different from the contact pieces  20  and the base member  60 , the pressing member  50  is not an essential member of the electrical connection device  1 . For example, as is obvious from  FIG. 6 , when the busbar  5  is in a state of being inserted in the insertion opening  34  formed between the contact piece  20 A and the contact piece  20 B, the engaging protrusions  67  of the base member  60  will not come out from the engaging holes  27  provided on the base portions  31  of the contact pieces  20 . As a result, the contact piece  20 A and the contact piece  20 B will not come off from the base member  60 . 
     However, when the busbar  5  is in a state before being inserted in the insertion opening  34  between the contact piece  20 A and the contact piece  20 B, e.g., in a state of  FIG. 5 , without a certain means, the contact piece  20 A and/or the contact piece  20 B could easily come off from the base member  60  through the insertion holes  65 . Therefore, it is preferable to provide the pressing member  50 , but it is not essential to provide the pressing member  50 . Here, alternately, it is also possible to enhance the effect of preventing the coming off by bending the end parts of the engaging protrusions  67  in an upright direction to make a cranked shape. 
     On the both left and right end portions of the base member  60 , there are provided notches  63 , each of which is composed of semicircular part and a rectangular part. Upon attaching the base member  60  to the wiring board  3 , without completely fixing onto the wiring board  3 , the electrical connection device  1  can be attached on the wiring board with the shoulder screws  80  disposed via the notches  63  so as to be able to float in surface directions on the planar surface  4  of the wiring board  3 . 
     More specifically, the diameter “b” of the notches  63  provided on the base member  60  is smaller than the diameter “c” of the screw heads  83  of the shoulder screws  80 , and is larger than the diameter “d” of the enlarged diameter shanks  32 , each of which is provided between the screw head  83  and screw threads  81  of the shoulder screw  80 . Moreover, the distance “e” between the shoulder screws  80  after being fixed on the wiring board  3  is set larger than a distance “f” between vertexes of the notches  63 A and  63 B. Therefore, even after the shoulder screws  80  are fixed on the wiring board  3 , the electrical connection device  1  can float in surface directions of the planar surface  4 . 
     By adding such floating action, it is achievable to easily allow the busbar  5  to displace relative to the electrical connection device  1  upon receiving the busbar  5  in the electrical connection device  1 . Here, needless to say, by suitably adjusting the dimensional relations, it is also possible to float the electrical connection device  1  only in one of the surface directions, instead of any directions of the surface. 
     In the embodiment, the cover  40  is an optional member to include, similarly to the pressing member  50 . The cover  40  is made of resin, and covers generally around the contact pieces  20 A and  20 B and covers generally the whole upper part of the electrical connection device  1 . With the cover  40 , it is achievable to protect the contact pieces  20 , as well as to protect users from electric shock. Here, even after attaching the cover  40 , it is still possible to access the contact pieces  20 A and  20 B, and the cover  40  will not interfere with movements of the contact pieces  20 A and  20 B. 
     The cover  40  mainly includes a pair of upright planar side walls  49 , a front wall  46 , a rear wall  47 , and a bottom planar part. The pair of the planar side walls  49  covers side surfaces of the arm portions  32 A and  32 B of the contact pieces  20 A and  20 B. The front wall  46  and the rear wall  47  are disposed to joint side edges of the side walls  49 , and have somewhat trapezoidal shapes at the bottom ends, i.e., open fan shapes. The bottom plate part joins between the side walls  49  and the front wall  49  or the rear wall  47 . On the bottom plate part, there are formed generally semicircular notches  45  so as to be able to place the shoulder screws  80 . 
     At the center of the tops of the front wall  46  and the rear wall  47 , there is provided a U-shaped access opening  43  to insert/remove the busbar  5 . The amount of insertion of the busbar  5  can be limited by adjusting the vertical depth of the access opening  43 . Through the access opening  43 , the busbar  5  can contact with the contact pieces  20 A and  20 B. Here, around an insertion opening  42  of the access opening  43 , it is also possible to provide a inclined guide surface  48  to make guiding of the busbar  5  easier. 
     Lastly, an operation of the electrical connection device  1  according to the embodiment of the present invention will be described. 
     Upon transitioning from the state of  FIG. 5  to the state of  FIG. 6 , i.e., from the state before holding the busbar  5  with the electrical connection device  1  to the state of holding the busbar upright with the electrical connection device  1 , it is possible to accommodate misalignment of the busbar  5  relative to the electrical connection device  1 , using the floating action of the electrical connection device  1  and the backlash of the contact pieces  20 . 
     Moreover, according to the embodiment of the present invention, using the notches  63  of the base member  60  and the shoulder screws  80 , the electrical connection device  1  is provided on the planar surface  4  of the wiring board  3  so as to be able to float in the surface directions, and the contact pieces  20  can move by leverage, using the base portions  31  as fulcrums. As a result, it is possible to accommodate the misalignment of the busbar  5  relative to the electrical connection device  1 , upon inserting the busbar  5  from the insertion opening  34  formed between the arm portion  32 A of the contact piece  20 A and the arm portion  32 B of the contact piece  20 B. 
     Upon insertion, the busbar  5  first abuts the inclined surfaces  48  of the cover  40 , and relatively large misalignment between the busbar  5  and the electrical connection device  1  is corrected by the floating action of the electrical connection device  1 . Then, the busbar  5  abuts the contact pieces  20 , and relatively small misalignment between the busbar  5  and the insertion opening  34  is corrected using the backlash of the contact pieces  20 . 
     In the embodiment, the insertion opening  34  is formed between the contact points  21 A′ and the contact points  21 B′ and between the contact points  22 A′ and the contact points  22 B′. The contact points  21 A′ are provided at the frame-like contact portion  21 A of the arm portion  32 A of the contact piece  20 A. The contact points  21 B′ are provided on the frame-like contact portion  21 A of the arm portion  32 B of the contact piece  20 B. The contact points  22 A′ are provided on the strip-like contact portions  21 A of the arm portion  32 A of the contact piece  20 A. The contact points  22 B′ are provided on the strip-like contact portions  22 B of the arm portion  32 B of the contact piece  20 B. 
     In the embodiment, the size “g” of the insertion opening  34  formed between those contact points are set smaller than a thickness “h” of the busbar  5 . Therefore, upon inserting the busbar  5  in the insertion opening  34 , the arm portion  32 A of the contact piece  20 A, especially the contact points  21 A′ and  22 A′ will certainly contact with the one planar surface  5 A of the busbar  5 . 
     Through this contact, the arm portion  32 A is urged to the side of the planar surface  4  of the wiring board  3 . In response to this, the leg portion  33 A of the contact piece  20 A is urged to the side of the wiring board  3  having the base portion  31 A as fulcrum. In short, upon holding the busbar  5 , the contact points  21 A′ and  22 A of the arm portion  32 A serve as power points, the base portion  31 A serves as a fulcrum, and the contact point  33 ′ of the leg portion  33  serves as a point of action. By leverage, the contact force occurred between the busbar  5  and the contact piece  20 A is transmitted to the contact point  33 A′ of the leg portion  33 A. As a result, the leg portion  33 A of the contact piece  20 A is urged to the side of the wiring board  3  and pressed onto the planar surface  4 . 
     Similarly, when the busbar  5  is inserted in the insertion opening  34 , the arm portion  32 B of the contact piece  20 B, especially the contact points  21 B′ and  22 B′ thereof certainly contact with the one planar surface  5 B of the busbar  5 . Through this contact, the arm portion  32 B is urged to the side of the planar surface  4  of the wiring board  3 . In response to this, the leg portion of the contact piece  20 B is urged to the side of the wiring board  3 , having the base portion  31 B as fulcrum. 
     As a result, by leverage, the contact force occurred between the busbar  5  and the contact piece  20 B is transmitted to the contact point  33 B′ of the leg portion  33 B, and the leg portion  33 B of the contact piece  20 B is urged to the side of the wiring board  3  and pressed to the planar surface  4 . As a result, it is achievable to reinforce the contact between the leg portions  33 A and  33 B and the wiring board  3 , and secure electrical connection of the contact pieces  20 A and  20 B to the wiring board  3  and to the busbar  5 . 
     In addition, upon holding the busbar  5  with the electrical connection device  1 , the leg portions  33 A and  33 B of the contact pieces  20 A and  20 B, which have spring property, contact with the busbar  5  with certain force, and the leg portions  33 A and  33 B of the contact pieces  20 A and  20 B also contact with the wiring board  3  with certain force. Therefore, the busbar  5  is stably held with the electrical connection device  1 . Furthermore, according to the above-described configuration, upon holding the busbar  5  upright with the electrical connection device  1 , it is possible to have the contact pieces  20  contact with the both planar surfaces  5 A and  5 B at the same time. Therefore, it is achievable to keep the force evenly exerted on the busbar  5  and the electrical connection device  1 . 
     Here, according to the embodiment, an example is described, in which the contact pieces  20  are a pair of contact pieces  20 A and  20 B, but the contact pieces  20  do not have to be a pair, nor plural. For example, it is also possible to provide only one contact piece by extending the abutting surface of the base portion in the upright direction so as to have it as a wall that faces the arm portion. As is obvious, also in this case, it is achievable to obtain effects of the present invention. 
     In addition, according to the above-described embodiment, the base member  60  has the engaging protrusions  67  and the pressing member  50  has the engaging recesses  52 . However, instead, the base member  60  can have the engaging recesses (not illustrated) and the pressing member  50  can have the engaging protrusions (not illustrated). Here, in this case, the pressing member  50  is an essential member. 
     The present invention is applicable in various electrical connection devices, in which a wiring board and a plate conductive member are electrically connected while holding the plate conductive member upright on a planar surface of the wiring board. 
     The disclosure of Japanese Patent Applications No. 2014-102533, filed on May 16, 2014, is 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.