Abstract:
A clamp-jaw contact assembly includes a stationary contact adapted to engage a meter socket cavity. A moveable contact is adapted to engage a meter bayonet. A unitary spring/pivot wire-formed U-shaped member pivotally mounts the moveable contact to the stationary contact and is adapted to bias the moveable contact toward the stationary contact upon insertion of the meter bayonet therebetween.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to contact assemblies and, more particularly, to a clamp-jaw contact assembly, such as for a watt-hour meter socket. The invention also relates to meter sockets employing clamp-jaw contact assemblies. 
     2. Background Information 
     Watt-hour meters are typically used by electric utilities to measure electrical consumption in residential, commercial and industrial applications. To accommodate the watt-hour meter, equipment is provided with a watt-hour meter socket. Such a meter socket contains a plurality of “meter jaws” to accept bayonet stabs or contacts on the base of the watt-hour meter. 
     Meter sockets having locking jaws for receiving the bayonet or blade contacts of a watt-hour meter are well known. See, for example, U.S. Pat. No. 3,281,550. Meter sockets are generally located in a rectangular enclosure having an opening in a top panel for receiving line cables and an opening in a bottom panel for receiving load cables. The meter socket is mounted to a back panel of the enclosure. A removable front panel has an opening for receiving the dome portion of the meter, which extends therethrough when coupled to the meter socket. 
     A typical residential meter socket is of the “plug-in type” in which the bayonet stabs on the meter are retained and clamped to corresponding meter jaws using the inherent spring pressure of the meter jaws. For some residential applications, and for the majority of commercial and industrial applications, a “clamp-jaw” type of meter socket is employed. In the clamp-jaw type meter socket, the clamping force of the jaws upon the meter bayonets is enhanced by the addition of a spring, such as a straight beam spring or a coil spring. 
     In a typical construction, the meter jaw assembly includes a stationary jaw or contact, and a moveable or pivoting jaw or contact. The moveable jaw, with the aid of the aforementioned spring, exerts pressure on the corresponding meter bayonet, thereby clamping it to the stationary jaw. 
     U.S. Pat. No. 5,775,942 discloses a meter socket employing a plurality of jaw-type contact assemblies including a stationary contact, a moveable contact and a conductor terminal. 
     FIG. 1 shows a prior clamp-jaw assembly  2 , which generally includes three component parts: a stationary contact  4  (as best shown in FIG.  2 ), a moveable contact  6  and a conductor terminal (not shown). The stationary contact  4  is preferably a one-piece construction including an elongated body  8  and a generally unshaped bottom portion  10  having a vertical extension member  12  and a conductor terminal interface  13 . The elongated body  8  includes a pair of wings  14 , which extend perpendicular to the elongated body  8 . Preferably, the stationary contact  4  is stamped and bent into shape from a single piece of conductive metal, such as copper. 
     The moveable contact  6  is pivotably mounted to the stationary contact  4  by a pivot pin  16 . The moveable contact  6  is also preferably a one-piece construction. The moveable contact  6  includes a back portion  18  having a pair of wings  20  (only one of the wings  20  is shown) extending substantially perpendicular to the back portion  18 . A low portion  22  of the moveable contact  6  is bent for receiving a biasing mechanism, such as a spring  24 , to bias a portion  26  of the moveable contact  6  to be in a clamped position with respect to the elongated body  8  of the stationary contact  4 . 
     Known technology for jaw-type contact assemblies typically employs both a spring and a separate machine driven tubular steel rivet to accomplish the respective clamping and pivoting actions. However, the rivet must be installed by a rivet setting machine or else staked manually, in order to retain the rivet in the jaw-type contact assembly. Also, a beam spring or coil spring is separately installed in that assembly in order to provide the desired clamping force. 
     There is room for improvement in clamp-jaw contact assemblies. 
     There is also room for improvement in watt-hour meter sockets and in meter socket clamp-jaw contact assemblies. 
     SUMMARY OF THE INVENTION 
     These needs and others are met by the present invention, which combines both spring clamping force and pivot functions in a unitary spring/pivot member, which may be assembled in a meter socket clamp-jaw contact assembly without the need for a machine operation. 
     As one aspect of the invention, a clamp-jaw contact assembly comprises: a stationary contact adapted to engage a meter socket cavity; a moveable contact adapted to engage a meter bayonet; and a unitary member pivotally mounting the moveable contact to the stationary contact and adapted to bias the moveable contact toward the stationary contact. 
     The unitary member may be a U-shaped wire-form or a wire-formed member. 
     The unitary member may be a spring/pivot member having a rectangular shape with a pair of ends and an open portion therebetween. 
     The stationary contact may include an elongated body and a pair of sides, which extend from the elongated body; the moveable contact may include a body portion and a pair of sides, which extend from the body portion; the sides of the stationary contact and the moveable contact may have openings; the unitary member may be a spring/pivot member having a first end, which passes through a first pair of the openings of a first pair of the sides of the stationary contact and the moveable contact; and the spring/pivot member may have a second end, which passes through a second pair of the openings of a second pair of the sides of the stationary contact and the moveable contact. 
     The unitary member may be a spring/pivot member having a first end, a second end and an opening therebetween; the stationary contact may include first and second openings; the moveable contact may include first and second openings; the first end of the spring/pivot member may engage the first openings of the stationary contact and the moveable contact; and the second end of the spring/pivot member may engage the second openings of the stationary contact and the moveable contact. 
     The unitary member may be a spring/pivot member having a general U-shape including a pair of ends disposed from a pair of sides disposed from a bias member, with the pair of ends pivotally mounting the moveable contact to the stationary contact. The stationary contact may include a surface. The moveable contact may include a first portion, which is pivotally mounted to the stationary contact, and a second portion proximate the surface of the stationary contact and adapted to be biased by the bias member of the spring/pivot member. 
     The stationary contact may be elongated and include a pair of protrusions. The sides of the spring/pivot member may engage the protrusions of the stationary contact. The moveable contact may pivot about the ends of the spring/ pivot member. The second side of the second portion of the moveable contact may engage the bias member of the spring/pivot member, in order to maintain the moveable contact in a clamped position with respect to the stationary contact. 
     As another aspect of the invention, a meter socket clamp-jaw contact assembly comprises: a stationary contact; a moveable contact; and a unitary spring/ pivot member pivotally mounting the moveable contact to the stationary contact and adapted to bias the moveable contact toward the stationary contact. 
     As another aspect of the invention, a meter socket comprises: a socket block including a plurality of cavities recessed therein; and a plurality of clamp-jaw contact assemblies mounted in the cavities of the socket block, each of the contact assemblies comprising: a stationary contact engaging a corresponding one of the cavities; a moveable contact adapted to engage a meter bayonet; and a unitary member pivotally mounting the moveable contact to the stationary contact and adapted to bias the moveable contact toward the stationary contact 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which: 
     FIG. 1 is an isometric view of a watt-hour meter clamp-jaw assembly. 
     FIG. 2 is an isometric view of the stationary contact of FIG.  1 . 
     FIG. 3 is an isometric view of a watt-hour meter clamp-jaw assembly in accordance with the present invention. 
     FIG. 4 is an isometric view of the spring/pivot member of FIG.  3 . 
     FIG. 5 is an isometric view of the moveable contact of FIG.  3 . 
     FIG. 6 is an isometric view of the watt-hour meter clamp-jaw assembly of FIG. 3 prior to the assembly of the spring/pivot member of FIG.  4 . 
     FIG. 7 is a cross-sectional view of a meter socket assembly as taken through three load end clamp-jaw contact assemblies, including the clamp-jaw assembly of FIG. 3, in accordance with an embodiment of the present invention. 
     FIG. 8 is an isometric view of a watt-hour meter clamp-jaw assembly in accordance with another embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is disclosed in connection with a clamp-jaw assembly for a watt-hour meter socket assembly. However, it will be appreciated that the invention is applicable to a wide range of clamp-jaw contact assemblies, which provide electrical connection to bayonet stabs, contacts or other types of electrical connections. 
     Referring to FIG. 3, a clamp-jaw assembly  30  of the present invention is shown. The clamp-jaw assembly  30  is suitable for use with a watt-hour meter socket, such as the meter socket assembly  72  of FIG.  7 . An example of such a watt-hour meter socket is disclosed in U.S. Pat. No. 5,775,942, which is incorporated herein by reference. The assembly  30  includes a stationary contact  32 , which is somewhat similar to the stationary contact  4  of FIG. 2, a moveable contact  34  (as best shown in FIG. 5) and a spring/pivot member  36  (as best shown in FIG.  4 ). The stationary contact  32  is preferably a one-piece construction including an elongated body  40  and a generally unshaped bottom portion  42  having a vertical extension member  44 . The stationary contact  32  includes a pair of wings  46 , which extend perpendicular to the elongated body  40  thereof. Preferably, each of the stationary contact  32  (e.g., made of copper) and the moveable contact  34  (e.g., made of copper or heat treated steel) are stamped and bent into shape from a single piece of conductive metal. As shown in FIG. 4, the spring/pivot member  36  is preferably formed from a suitable structure, such as a wire  37  (e.g. made of spring steel), which is bent into a square or rectangular shape having a pair of ends  47 , 48  with an open portion  49  therebetween. 
     The moveable contact  34  is pivotably mounted to the stationary contact  32  by the ends  47 , 48  of the spring/pivot member  36 . The moveable contact  34  is also preferably a one-piece construction. The spring/pivot member ends  47 , 48  pass through openings  50  (only one opening  50  is shown in FIGS. 3 and 6) of the wings  46  of the stationary contact  32 . The moveable contact  34  includes a back portion  52  and a pair of wings  54  extending substantially perpendicular to the back portion  52 . The spring/pivot member ends  47 , 48  also pass through openings  56  of the wings  54  of the moveable contact  34 . An arcuate low portion  58  of the moveable contact  34  is engaged by a low portion  60  of the spring/pivot member  36 , in order to provide a clamped position (as best shown in FIG. 7) of the moveable contact  34  with respect to the stationary contact  32  after insertion of a meter bayonet  64  (as shown in phantom line drawing) therebetween. The center V-shaped portion of the moveable contact  34  minimizes bending or deformation of such contact. 
     FIG. 6 shows the relative positions of the stationary contact  32  and the moveable contact  34  before the assembly of the spring/pivot member  36  of FIGS. 3 and 4. The moveable contact  34  is first positioned between the wings  46  of the stationary contact  32 . Then, with reference to FIG. 3, the low portion  60  of the spring/pivot member  36  is moved past the arcuate low portion  58  of the moveable contact  34  and proximate the opposite surface  66  thereof. Finally, the ends  47 , 48  are inserted within the corresponding openings  50  and  56  of the respective contacts  32  and  34 . 
     As shown in FIGS. 3,  6  and  7 , unlike the wings  14  of the stationary contact  4  of FIG. 1, there are one or more protrusions  62  on the wings  46  of the stationary contact  32 . As best shown in FIG. 7, these protrusions  62  bias the wire spring/pivot member  36 , in order that the stationary and moveable contacts  32 , 34  are biased closed against the meter bayonet  64  (as shown in phantom line drawing). With the meter bayonet  64  in the position shown in FIG. 7, the moveable contact  34  pivots counter-clockwise (with respect to FIG.  7  and with respect to the bottom right of FIG. 3) about the ends  47 , 48  of the spring/pivot member  36 . In turn, a surface  66  of the arcuate low portion  58  of the moveable contact  34  engages the low portion  60  of the spring/pivot member  36 . As a result, upper portions  68  of the sides  69  of the spring/pivot member  36  engage the protrusions  62  of the wings  46  of the stationary contact  32 . The low portion  60  of the spring/pivot member  36 , thus, provides the bias to the arcuate low portion  58  of the moveable contact  34 , in order to maintain the moveable contact  34  in a clamped position with respect to the stationary contact  32 , with the respective surfaces  59  and  70  clamping the meter bayonet  64  as shown in FIG.  7 . No additional parts are required to complete the clamp-jaw assembly. 
     FIG. 7 shows a cross-sectional view taken through load end clamp-jaw contact assemblies  30 , 30 ′, 30 ′ of a meter socket assembly  72  formed in accordance with the present invention. The contact assemblies  30 ′ are similar to the contact assembly  30 , except that they provide a mirror-image, as shown. An insulative base or socket block  74  of the meter socket assembly  72  includes a series of cavities  76  recessed into the block for receiving each of the contact assemblies  30 , 30 ′, 30 ′. These contact assemblies are bolted to the socket block  74  using screws  78  inserted into openings  79  in a bottom portion of the block and into openings  90  (as shown in FIG. 3) of the contact assemblies. 
     Referring to FIG. 8, another clamp-jaw assembly  80  is shown. The assembly  80  includes a stationary contact  82 , which is somewhat similar to the stationary contact  32  of FIG. 3, a moveable contact  84 , which is somewhat similar to the moveable contact  34  of FIG. 3, and a spring/pivot member  86 , which is somewhat similar to the spring/pivot member  36  of FIG.  3 . Here, unlike FIG. 3, but like the contact assemblies  30 ′ of FIG. 7, the stationary contact  82  has a conductor terminal interface  88 , which is located on the opposite side (i.e., toward the top left of FIG. 8 rather than conductor terminal interface  89 , which is located on the bottom right of FIG. 3) of the clamp-jaw assembly  80 . Also, the spring/pivot member  86  has bend portions  91 , which accommodate a relatively wider meter bayonet (not shown) than the meter bayonet  64  of FIG.  7 . 
     The disclosed watt-hour meter clamp-jaw assemblies  30 , 30 ′, 80  eliminate a separate rivet and the resulting staking operation. A pivot mechanism is provided by shaping the spring/pivot member  36  from the wire  37 , in order to provide both a pivot/clamping mechanism as well as suitable spring force in order to securely clamp the meter bayonet  64  to the surface  70  of the stationary contact  32  by the surface  59  of the moveable contact  34 . The openings  50  and  56  on both the stationary and moveable contacts  32  and  34 , respectively, provide a retaining mechanism for the ends  47 , 48  of the wire spring/pivot member  36 . 
     Counter-clockwise rotation (with respect to FIG. 7) of the moveable contact  34  as caused by the insertion of the meter bayonet  64  between the surface  70  of the stationary contact  32  and the surface  59  of the moveable contact  34  causes the arcuate low portion  58  of the moveable contact  34  to disengage from the vertical extension member  44  of the stationary contact  32 . This causes the upper portions  68  of the spring/pivot member  36  to be deflected by the protrusions  62  of the wings  46  of the stationary contact  32 , which bends the member  36  and causes the low portion  60  of the spring/pivot member  36  to provide the bias (counter-clockwise with respect to FIG. 7) to the arcuate low portion  58  of the moveable contact  34 . As a result, this clamps the meter bayonet  64 , which is sandwiched between the surface  59  of the moveable contact  34  and the surface  70  of the stationary contact  32 . 
     While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.