Patent Publication Number: US-8979573-B1

Title: Connector block with spring-loaded electrical terminal assemblies

Description:
FIELD OF THE DISCLOSURE 
     Disclosed are electrical terminal assemblies for forming electrical connections between wire conductors and rigid conductors, and in particular screwless electrical terminal assemblies in which a spring presses the wire conductor against the rigid conductor. 
     BACKGROUND OF THE DISCLOSURE 
     Connector blocks that include “screwless” electrical terminals or spring terminals for forming electrical connections between rigid conductors or current bars in the connector block and wire conductors are known. The spring terminal utilizes a compressed spring that generates a spring force pressing the wire conductor against the current bar to form the electrical connection therebetween. 
     A known type of spring terminal utilizes the current bar as a spring retainer. A portion of the current bar is formed as a spring retainer that retains both ends of the compressed spring. The current bar is made of expensive electrically conductive material (typically a copper alloy). Forming the spring retainer in the current bar is expensive both in material cost and manufacturing cost. 
     Another type of known spring terminal includes a spring in which the spring has a first leg that lies against one side of the current bar and an extension attached to a second leg, with an opening in the extension to receive the current bar. The second leg presses against the second side of the current bar to maintain the spring in the compressed condition. Manufacture and assembly of the spring with the current bar is relatively expensive. 
     Yet another known type of spring terminal the current bar extends along one wall of a rigid U-shaped member, the spring compressed between the other wall and the contact bar. In this type of spring terminal the U-shaped member effectively compresses the spring between the legs of the member. The U-shaped member is a relatively large component and so material cost is high. 
     Thus there is a need for a connector block having spring terminals that utilize a spring retainer that is not formed as part of the current bar, has relatively low cost, and is easier to assemble. 
     SUMMARY OF THE DISCLOSURE 
     Disclosed in one or more embodiments is a connector block having improved spring terminals that includes a spring retainer that is not formed as part of the current bar, is a relatively low cost member, and enables the spring terminal to be installed in the connector block at low cost. 
     A spring terminal includes a current bar, a spring retainer, and a spring, the spring retainer not integral with the current bar and not integral with the spring. 
     The spring includes first and second end portions, with the spring compressed between a first portion of the current bar and a first portion of the spring retainer, the first end portion of the spring in pressure contact with the first portion of the current bar and the second end portion of the spring in pressure contact with the first portion of the spring retainer. The spring urges the spring retainer in a first direction away from the first portion of the current bar. 
     The spring retainer includes a first abutment surface facing the first direction and the current bar includes a first abutment surface facing the first abutment surface of the spring retainer. The first abutment surface of the current bar is located to engage the first abutment surface of the spring retainer with movement of the spring retainer in the first direction whereby the first abutment surface of the current bar resists movement of the spring retainer urged by the spring away from the first portion of the current bar. 
     The spring retainer is preferably formed as a stamped member from metal plate. Because the spring retainer is not formed in the current bar, the spring retainer can be made from a low-cost material such as steel having better material properties to function as a spring retainer. 
     In a preferred embodiment, the first and second portions of the current bar are joined together by a ninety-degree bend. The second portion of the current bar includes a notch formed on a peripheral surface of the current bar that includes the abutment surface of the current bar. The spring retainer includes a flange that is closely received in the notch, the abutment surface of the spring retainer located on the flange surface facing the abutment surface of the current bar. 
     The spring terminal disclosed herein has a number of advantages. The spring retainer is a low-cost component with reduced manufacturing cost. Identical spring retainers can be used with connector blocks having multiple current bars with different bar geometries, simplifying and reducing inventory costs. The spring terminal is easy to assemble. 
     Other objects and features will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawing sheets. 
    
    
     
       BRIEF SUMMARY OF THE DRAWINGS 
         FIG. 1  is an exploded view of a connector block having spring terminal assemblies; 
         FIG. 2  is a closer, exploded view of one of the spring terminal assemblies shown in  FIG. 1 ; and 
         FIG. 3  is a view of the spring terminal assembly shown in  FIG. 2  forming an electrical connection with a wire conductor. 
     
    
    
     DETAILED DESCRIPTION 
     The figures illustrate a connector block  10  for forming electrical connections between wire conductors and current bars  16  carried by the connector block  10 . The connector block  10  includes a housing  12  and a number of like electrical terminal or spring terminal assemblies  14  in the housing  12 , each terminal assembly  14  configured to form an electrical connection between a wire conductor and a respective current bar  16 . Because in the illustrated embodiment the terminal assemblies  14  are identical assemblies (although each of the current bars have different geometries), only a single terminal assembly will be described in detail. 
     The terminal assembly  14  includes an end portion of a conductor bar or current bar  16 , a spring  18 , and a support plate or spring retainer  20 , the spring retainer  20  a body separate from and not integral with the current bar  16  or the spring  18 . A respective pusher tool or actuator tool  94  is associated with each terminal assembly  14  and is used to open and close the terminal assembly  14  when inserting or removing a wire conductor. 
     The current bar  16  is an elongate and rigid electrically-conducting member having a generally rectangular cross-section. The current bar  16  has a terminal end portion  22  and a tail end portion  24 . The terminal end portion  22  forms part of the terminal assembly  14  and includes a first, free end contact portion  26  and a second retention portion  28  joined to the contact portion  26  by a right-angle bend  30 . The tail end portion  24  extends away from the retention portion  28  to a free end portion  32  configured for making an electrical connection with another circuit element. The illustrated tail end portion  24  is configured to electrically connect to a circuit board, and the tail end portion of each current bar of the conductor block has a different geometry. Other current bar geometries and configurations, including the tail end portion  24  itself forming part of another terminal assembly  14  are possible. 
     The conductor contact portion  26  has a flat contact surface  34 , with a pawl or tooth  35  extending from the surface  34 . 
     The conductor retention portion  28  has a through-opening  36  extending through the thickness of the current bar and spaced from the bend  30 . The opening  36  is formed as a rectangular notch in an upper peripheral surface  38  of the retention portion  28 . 
     The spring  18  is a V-spring or leaf-spring made from spring steel and has a first end portion or first leg  40  and a second end portion or second leg  42 , the legs  40 ,  42  extending outwardly away from each other from an arcuate center spring portion  44   
     The spring retainer  20  is formed from relatively thin steel plate and includes a generally flat, triangular web  46  having a first side  48  and a second side  50 , the sides  48 ,  50  defining a right angle, with first and second flanges  52 ,  54  extending in the same direction away from the web  46 . The first flange  52  has a generally flat inner surface  56  that is perpendicular to the web  46 . The second flange  54  has a curved upper flange portion  58  that bends away from the web  46  and a lower flange portion  60  that has a generally flat inner surface  62 , the surface  62  perpendicular to the web  46  and also perpendicular to the first flange surface  56 . 
     The housing  12  is made of or molded from a non-conductive material such as plastic resin as is known in the connector block art, and includes a side wall  64  closing a first side of the housing  12  and a peripheral wall  66  extending from the side wall to the second side of the housing, the peripheral wall  66  defining the interior of the housing  12 . The housing  12  is configured to be a slice housing, that is, so configured that a number of housings  12  can be placed side-by-side and connected to adjacent housings  12  to form the connector block  10 . An example of a connector block formed from a number of slice housings is disclosed in Correll, U.S. Pat. No. 7,491,096, and incorporated by reference as if fully set forth herein. In other embodiments the connector block  10  can be formed from a single housing  12 . 
     The housing  12  has conventional walls, posts, and lugs extending from the sidewall  64  and the peripheral wall  66  to receive and support the current bars  16  in the housing  12  and to interconnect adjacent slice housings  12 ; these features are conventional and so will not be described herein. The housing  12  also includes structural elements associated with the terminal assemblies  14 ; each set is associated with a respective terminal assembly  14 . A description of only one set of elements will be described below. 
     A “vertical” wall  68  and a “horizontal” wall  70  extend from the sidewall  64  and are configured to extend along and support the current bar conductor portion  26  and the retainer portion  28  respectively. A spring post  72  extends from the sidewall  64  and carries the center spring portion  44  to mount the spring  18  in the housing  12 . An “L” shaped wall  74  extends from the sidewall  64  and is spaced from the sidewall  68 . The leg  74  includes a “vertical” wall leg  76  parallel to and facing the vertical wall and a second, shorter “horizontal” wall leg  78  facing the horizontal wall  70 . 
     The horizontal wall  70  includes a notch  80  formed on the inner side of the wall, the notch  80  sized and positioned to closely receive the spring retainer second flange  54 . The vertical wall leg  76  includes a notch  82  formed on the inner side of the wall leg, the notch  82  sized and positioned to closely receive the spring retainer first flange  52 . The upper ends of each notch  80 ,  82  have opposed tapered surfaces that assist in guiding the respective spring retainer flanges  52 ,  54  into the notch. 
     A tool opening  84  and a conductor wire opening  86  extend through the peripheral wall  66 . The tool opening  84  is offset from the spring post  72  towards the vertical wall  68 . The conductor wire opening  86  is aligned with the contact surface  34  of the current bar  14  so that a conductor wire inserted through the conductor opening  86  is immediately adjacent the contact surface  34 . 
     Assembly and operation of the spring terminal  14  is described next. The current bar  14  is placed in the housing  12 , with the terminal portion  22  extending along the vertical housing wall  68  and the retainer portion  28  extending along the horizontal housing wall  70 . The spring  18  is compressed, placed on the spring post  72 , and released. The spring  18  is configured such that upon release, the first spring leg  40  makes pressure contact with the current bar contact face  34  and the second spring leg  42  makes pressure contact with the vertical wall leg  76 . 
     The spring retainer  20  is then installed by being placed over the current bar  18  with the first flange  52  over and aligned with the wall leg notch  82  and the second flange  54  over and aligned with the horizontal wall notch  80 . The spring retainer  20  is then moved towards the housing  12 , with the horizontal wall leg  78  assisting in the proper lateral positioning of the spring retainer  20  relative to the housing  12 . As the flanges  52 ,  54  are received in the respective notches  82 ,  80  the first flange  52  moves into contact with the spring leg  42 , moving the second spring leg  42  away from the wall leg  74  and causing the spring leg  42  to be in pressure contact with the first flange contact surface  56 . In this way, the spring  18  is compressed between the current bar  14  and the first spring retainer flange  52 , with the spring force applied by the leg  74  carried by the metal spring retainer  20  instead of by the resin wall leg  74 . 
     When the spring retainer  20  is fully installed in the housing  12 , the first spring retainer flange  52  is closely received in the vertical notch  82  and the second spring retainer flange  54  is closely received in the horizontal notch  84 . The first flange contact surface  56  faces the current bar contact surface  34 , and the spring  18  compressed between the two surfaces  56 ,  34 . The second flange upper portion  58  extends through and is closely received in the slot or notch  36  of the current bar retainer portion  28 , and the second flange lower portion  60  is closely received in the horizontal wall notch  80  and faces and extends along the outside of the current bar retainer portion  28 . 
     The spring force generated by the spring  18  biases or urges the spring retainer  20  away from the current bar contact surface  34 . The spring force also urges the second flange upper portion  58  towards the side of the notch  36  away from the contact surface  34 . Because the upper flange portion  58  is closely received in the notch  36 , the notch surface  88  facing the flange portion  58  and the flange surface  90  facing that side of the notch  80  form facing cooperating abutment surfaces. By curving the upper flange portion  58 , the surface areas of the cooperating abutment surfaces  88 ,  90  are increased. The abutment surfaces  88 ,  90  are disposed to engage one another and resist movement of the spring retainer  20  away from the current bar contact surface  34 . In this way, a portion of the spring force is transmitted from the spring retainer  20  to the current bar  16 , reducing the force applied to the resin housing components to resist relative movement of the spring retainer  20 . The second flange lower portion  60  further cooperates with the current bar  16  to resist twisting of the spring retainer  20  urged by the spring force. 
     The left-most terminal assembly  14  as viewed in  FIG. 3  is shown prior to insertion of a wire conductor. The current bar pawl  35  acts as a stop cooperating to maintain compression of the spring. The tool  94  is normally retained with the housing  12  as shown in the drawing. To insert a wire conductor  92  into the terminal assembly  14  the tool  94  is pushed further into the housing  12  and further compresses the spring  18 , deflecting the first spring leg  40  towards the first spring retainer flange  52  and spacing the spring  18  away from the current bar contact surface  34 , thereby opening the terminal assembly  14 . 
     The middle terminal assembly  14  as viewed in  FIG. 3  illustrates the opened terminal assembly  14 . The wire conductor  92  is then inserted through the conductor opening  86  and the tool  94  is withdrawn after the wire conductor is properly positioned in the housing  12 , decompressing the spring  18  and closing the terminal assembly  14 . 
     The right-most terminal assembly  14  as viewed in  FIG. 3  illustrates a closed electrical terminal  14  forming an electrical connection with the wire conductor  92 . The spring  18  presses the wire conductor  92  against the current bar contact surface  34  to form an electrical connection between the current bar  16  and the wire conductor  92 , the pressure contact of the spring leg  40  against the current bar contact surface  34  transmitted through the wire conductor  92 . Removal of the conductor wire  92  is essentially the reverse of insertion. 
     While the spring  18  is further compressed by the tool  94 , additional spring force is applied to the spring retainer  20  urging the retainer  20  away from the current bar contact surface  34 . This additional spring force is distributed by the abutment surfaces  88 ,  90  from the spring retainer  18  to the current bar  16  to reduce additional loading of the resin housing components by the additional spring compression. 
     In other embodiments, a connector block  10  could include only a single current bar  16 , or could have a number of current bars  16  in which the current bar terminal portions  22  have varying geometries wherein each terminal assembly  14  utilizes a different-shaped spring  18  and/or a different-shaped spring retainer  20 . In yet other possible embodiments the current bar retainer portion slot  36  could be formed as a through-hole totally surrounded by the current bar. In yet further possible embodiments the spring retainer upper flange portion  58  could fit in the slot  36  with clearance such that the engagement surfaces  88 ,  90  engage each other with movement of the spring retainer  20  away from the contact surface  34  only when the tool  92  is deflecting the spring  18 , the vertical wall leg  74  supporting the spring retainer  18  against the spring force otherwise. 
     While one or more embodiments have been described, it is understood that this is capable of modification and that the disclosure is not limited to the precise details set forth but includes such changes and alterations as fall within the purview of the following claims.