Abstract:
An integral wall plate and power receptacle are provided for flush mounting on an electrical box or support. In that the wall plate and receptacle are made of insulating material the grounding of the wall plate is not required. The power receptacle includes a number of chambers into which contacts are selectively placed. Identification tabs on the contacts and keyways on the walls of the chambers limit insertion of the contacts to selected chambers and orient the contacts. The wall plate provides a smooth transition from the receptacle to thinned edges which receive mounting fasteners. An insert covers the base members and retains the contacts in their respective chambers while providing a smooth finished look to the wall plate.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is directed to the field of power receptacles and more particularly to a flush mount power receptacle with an integral wall plate which does not have to be grounded. 
     2. Description of the Prior Art 
     A typical prior art device includes a base member of insulating material into which electrical contacts are placed and closed by a cap of insulating material. The base member is mounted in an aperture of a metal mounting plate and riveted thereto. A metal strap extends from the rivet adjacent to the ground contact to the ground contact to ground the metal mounting plate. Slots and keyhole apertures permit the mounting plate to be mounted to an electrical box or support. The cap extends beyond the mounting plate. The extension of the cap and the difference in materials and color make the device appear unfinished. 
     SUMMARY OF THE INVENTION 
     The invention is directed to a flush mount power receptacle with integral wall plate. A base member is formed with a plurality of separate chambers extending from a first end to a second end into which are placed electrical contacts. The contacts are held in place in the chambers by retainers on the back surface of an insert coupled to the base member by locking tabs and a fastener extending through the insert into the base member. A wall plate is molded onto or otherwise attached to the base member and extends beyond it to cover an electrical box or support to which the receptacle is mounted. A recess in the wall plate adjacent the base member permits the insert to be positioned flush with the top surface of the wall plate in the central region of the wall plate. The wall plate is tapered from the central region to each of the four side edges to provide a smooth transition from the receptacle to a mounting surface. A plurality of slots and keyhole apertures permit the wall plate to be mounted to an electrical box or support. In that the wall plate is made of insulating material as is true of the body member no grounding strap is required. When the insert is in place, the wall plate provides a pleasing, finished appearance. 
     The electrical contacts are each provided with two identification tabs that mate with key ways in the walls of the separate chambers so that only a particular electrical contact type can be placed within each chamber and each contact admitted is properly oriented. Slots in the insert permit only the correctly shaped and oriented prongs of an electrical plug to be inserted into the electrical contacts. It is an object of this invention to provide a novel flush mount power receptacle with integral wall plate. 
     It is an object of this invention to provide a novel flush mount power receptacle with integral wall plate formed of insulating material which does not require grounding of the wall plate. 
     It is another object of this invention to provide a novel flush mount power receptacle with integral wall plate and insert which when assembled provides a smooth, unbroken surface which is aesthetically pleasing. 
     It is yet another object of this invention to provide a novel flush mount power receptacle with integral wall plate and base member having chambers therein each to receive only one type of electrical contact and to orient such contact with respect to said face plate. 
     It is still another object of this invention to provide a novel flush mount power receptacle having a base member containing a plurality of chambers, each chamber containing a particular electrical contact type and an insert having a set of apertures therein to admit the prongs of a selected electrical plug therein. 
     Other objects and features of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principles of the invention, and the best modes which are presently contemplated for carrying them out. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawings in which similar elements are given similar reference characters: 
     FIG. 1 is a top plan view of a power receptacle and mounting plate according to the prior art. 
     FIG. 2 is a side elevational view of the device of FIG.  1 . 
     FIG. 3 is a top plan view of a flush mount power receptacle with integral wall plate constructed in accordance with the concepts of the invention. 
     FIG. 4 is a side elevational view of the device of FIG.  3 . 
     FIG. 5 is a top plan view of the base member of the device up FIG. 3 with the insert removed to show details of the internal chambers. 
     FIG. 6 is a front right perspective view of the base member of FIG.  5 . 
     FIG. 7 is a front left perspective view of the base member of FIG.  5 . 
     FIG. 8 is top plan view of the base member of FIG. 5 showing the keyways therein and the contacts which can be inserted into each chamber of the base member. 
     FIG. 9 is an exploded, top perspective view of the device of FIG.  3 . 
     FIG. 10 is an exploded bottom, perspective view of the device of FIG.  3 . 
     FIG. 11 is a top perspective view of a further insert, which can be used with the device of FIG.  3 . 
     FIG. 12 is a bottom perspective view of the insert of FIG.  11 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning now to FIGS. 1 and 2 a power receptacle  10  with mounting plate  12 , according to the prior art is shown. Power receptacle  10  is made up of a base  14  which contains chambers (not shown) into which are placed electrical contacts (not shown). A cap  16  is coupled to the base  14  once the contacts are in place in the chambers. The diameter of cap  16  is greater than the diameter of base  14  to provide a step  18 . The cap  16  is coupled to the base  14  once the contacts are in place in the chambers. The diameter of cap  16  is greater than the diameter of base  14  to provide a step  18 . The cap contains slots  20 ,  22  and  24  and a rounded aperture  26  to receive the prongs of an electrical plug (not shown). Four rivet apertures are placed in the cap  16  to receive rivets  28  which fasten the cap  16  and base  14  to mounting plate  12 . The step  18  rests on the front surface of the mounting plate  12  to position the base  14  and cap  16  with respect to the mounting plate  12 . A grounding strap  30  is coupled by a rivet  28  to the mounting plate  12 . The free end of the grounding strap  30  is connected to the ground contact within the base  14  (not shown) so that a grounding conductor coupled to the ground contact is also coupled to grounding strap  30  and thus the mounting plate  12  is grounded. A series of slots  32  extend inwardly from the side edges  34  and  36 . The slots  32  on side edge  34  are open whereas the slots  32  on side edge  36  are closed by removable knock-outs  38 . A series of keyhole apertures  40  are adjacent but spaced apart from side edges  42  and  44 . Each of the keyhole apertures  40  is made up of an entry aperture  46  and a slot  48  extending therefrom and communicating with entry aperture  46 . The keyhole apertures  40  alongside edge  44  are closed by removable knock-outs  50 . As shown by FIG. 2, the cap  16  extends above the top surface of mounting plate  12 , and this coupled with the difference in materials between the cap  16  and mounting plate  12  makes the receptacle appear unfinished. 
     Referring now to FIGS. 3 to  10  a flush mount power receptacle  60  with integral wall plate  66  constructed in accordance with the concepts of the invention is shown. Power receptacle  60  has a base member  62  which contains a number of separate chambers  64  to receive electrical contacts therein as will be described below. Coupled to the base member  62  is a wall plate  66  having a generally flat central position  68  (see FIG. 4) and tapering smoothly to each of the four side edges  70 ,  72 ,  74  and  76 . The wall plate  66  may be molded to the base member  62  or it may be attached thereto by the use of bonding agents, adhesives, sonic welding or the like. A recess  78  (see FIG. 9) in central portion  68  is arranged to receive an insert  80  so that the top flat surface  82  of insert  80  is flush with the top surface of the remainder of central portion  68 . A plurality of apertures (see FIG. 3) extend through insert  80  so that the prongs of an appropriate electrical plug (not shown) can be inserted through such apertures and into engagement with the electrical contacts in chambers  64 . In FIG. 3 the apertures required for a NEMA 14-30R plug and receptacle is shown. Two straight apertures  84  receive the straight prongs of a NEMA 14-30R plug, while U-shaped aperture  86  receives the generally U-shaped ground prong and the L-shaped aperture  88  receives the generally L-shaped prong. In FIG. 11 insert  90  has apertures arranged according to NEMA 14-50R. Three straight apertures  92  receive the straight prongs of the NEMA 14-50R plug (not shown) while U-shaped aperture  94  receives the generally U-shaped ground prong. The apertures through an insert can be arranged to conform to many other NEMA standard plug and receptacle combinations. 
     Extending from the bottom surface  96  of insert  80  are four locking tabs  98 , as best shown in FIG. 9, each of which is arranged to pass through a corresponding locking aperture  100  in the floor of recess  78  and grip the rear surface of the rim  102  (see FIG. 10) about the base member  62 . To initially align and orient the insert  80  with the base member  62 , a fin  104  extending from the bottom surface  96  of the insert  80  (see FIG. 10) mates with an aperture  106  in the base member  62  (see FIG.  5 ). Unless the fin  104  is aligned with aperture  106  the insert  80  cannot be assembled to base member  62 . To complete the assembly of the insert  80  to the base member  62  a self-taping screw  108  is passed through assembly aperture  110  in insert  80  and into aperture  112  in the base member  62 . The assembly aperture  110  is counter-sunk to permit the head of screw  108  to be flush with the top surface  82  of insert  80  when the screw  108  is in its final position. The aperture  112  has a diameter less than the diameter of the self-taping screw  108  and the screw  108  cuts a thread into the walls defining aperture  112  to prevent removal of the screw  108  while holding the insert  80  and base member  62  in assembly. Because the wall plate  66  and the insert  80  are formed of insulating material such as natural or synthetic rubber, plastics or the like, there is no need to ground the wall plate  66  and the grounding strap has been omitted. 
     To mount the power receptacle  60  with integral wall plate  66  to an electrical box or support surface (not shown) a series of slots and keyhole apertures are placed adjacent the side edges of wall plate  66 . Two elongate slots  114  are placed adjacent each of the side edges  70  and  72 . Each of the slots  114  has a ridge  116  about all of the slot  114  except the entry  118 . A knock-out  120  covers the slots  114  and only the slots  114  to be used have their knock-outs  120  removed. The ridges  116  are engaged by the underside of fasteners passed through slots  114 . The ridges  116  permit the fastener heads to be recessed below the surface of the wall plate  66  (not shown) but securely grip the wall plate  66 . Side edges  74  and  76  each have two keyhole apertures  122  adjacent but spaced from the side edges  746 ,  76 , respectively. Each keyhole aperture  122  has an entry aperture  124  from which extends a slot  126 . A ridge  128  extends about the slot  126 . A knock-out  130  covers each of the keyhole apertures  122  and knock-outs  130  are removed as required. The ridges  128  serve the same purpose as ridges  116  of slots  114 . 
     Contacts (see FIGS. 9 and 10) are placed in the Chambers  64  in accordance with their function and the plug/receptacle configuration. Contacts  140  are arranged to receive the flat straight prongs of an electrical plug. Each contact  140  is generally U-shaped having at one end two jaws  142  between which is placed a flat, straight prong of an electrical plug. The ends  144  of the jaws  142  are outwardly directed as shown in FIGS. 9 and 10 to facilitate entry of the prong between jaws  142 . At the opposite end of Contact  140  is placed a screw operated conductor clamp  146 . The bared end of an electrical conductor (not shown) is inserted between a bridge  148  and the end of a screw  150 . As, the screw  150  is tightened it forces the bared end of the conductor against the bridge  148  thus retaining the conductor in the conductor clamp  146 . Contact  152  is similar to contact  140  except the jaws  154  are initially spread apart because of the width of the ground prong of an electrical plug. The jaws  154  are outwardly deflected by the ground prong of the plug which securely grips the sides of the ground prong of the plug. Contact  156  is similar to contact  140  except that jaw  158  is as wide as jaw  142  but jaw  160  is about one half of the width of jaw  142 . This permits contact  156  to grip one leg of the L-shaped prong of the plug. Each of the contacts  140  and  152  have stabilizing bars  162  on both jaws  142  and  154 , respectively, and contact  156  has a stabilizing bar  162  only on jaw  158 . The stabilizing bars  162  each engage a positioning rib on the side walls of the chambers  64  to support the contacts in the desired position within its respective Chamber  64 . 
     Each of the contacts  140 ,  156 ,  140  and  152  have two identification (ID) tabs  164  adjacent the screw operated conductor clamp  146  (see FIG.  8 ). ID tabs  164   a ,  164   b ,  164   c  and  164   d  extend along a top edge of the contacts  140 ,  156 ,  140  and  152  while ID tabs  164   e ,  164   f ,  164   g  and  164   h  extend along the spaced apart parallel bottom edge of the contacts  140 ,  156 ,  140  and  152 . The ID tabs on each edge can take one of two possible positions as shown by ID tabs  164   e  and  164   f , thus providing four discrete combinations. These ID tabs  164  in conjunction with keyways to be described below, are used to prevent the entry of a contact into a chamber  64  unless it matches the chamber  64  configuration and orients the jaws  142 ,  154 ,  158  and  160  correctly for the prongs of the electrical plug to be inserted. 
     FIGS. 5 to  8  depicts base member  62  showing the chambers  64   a ,  64   b ,  64   a  and  64   c . Chambers  64   a  have a top internal rib  166  which defines a keyway  168  and a bottom internal rib  170  which defines a keyway  172 . Only a contact having ID tabs  164   a  and  164   e  in the positions of keyways  168  and  172  will be permitted to enter cavity  164   a  and then only when the ID tabs  164   a  and  164   e  are aligned with keyways  168 ,  172  (see FIG.  8 ). Positioning ribs  174  on the side walls of the chambers  64   a ,  64   b ,  64   a  and  64   c  in conjunction with stabilizing bars  162  position the contact in its respective chambers and prevent movement of the contacts when the plug blades are inserted. Chamber  64   b  has a top internal rib  176  which defines a keyway  178  and a bottom internal rib  180  which defines a keyway  182 . Only contact  156  has ID tabs  164   b  and  164   f  which can be aligned with keyways  178  and  182  thus permitting contact  156  to enter chamber  64   b  in its correct orientation. Similarly, chamber  64   c  has a top internal rib  184  which defines a keyway  186  and a bottom internal rib  188  which defines a keyway  190 . Ground contact  152  has ID tabs  164   d  and  164   h  in positions corresponding to keyways  186 ,  190  and can be inserted in chamber  64   c  properly oriented. To retain the contacts  140 ,  156 ,  140  and  152  in their respective chambers  64   a ,  64   b ,  64   a  and  64   c  a series of retainers is used as shown in FIG.  10 . The retainers have complimentary shapes to the apertures in the insert  80  and top edges which engage the free ends of the contacts to hold the contacts in the correct position. Retainers  192  are rectangular with a straight slot  194  and a top edge  196  thereabout. The free ends of contacts  140  engage edges  196  to hold contacts  140  in place and slot  194  permits flat, straight prongs to be inserted through slots  194  into contacts  140 . Retainer  198  is L-shaped with an L-shaped slot  200  and a top edge  202 . An additional positioning tab  204  is provided for contact  156 . The ends of the jaws  158 ,  160  of contact  156  will engage top edge  202  of retainer  198  to hold the contact  156  in place while permitting an L-shaped prong of a suitable plug to be inserted through L-shaped slot  200  into contact  156 . U-shaped retainer  206  has a U-shaped slot  208  and a top edge  210 . The ends of contact  152  will engage top edge  210  to fix the position of contact  152  and the slot  208  will permit the U-shaped ground prong of a plug to enter slot  208  and be positioned between jaws  154  of contact  152 . 
     To assemble the flush mount power receptacle  60  with integral wall plate  66  the following sequence is followed. A base member  62  with a wall plate  66  attached is positioned such that the cavities  64   a ,  64   b ,  64   a  and  64   c  are oriented as shown in FIG.  5 . Next the contacts  140  are placed in cavities  64   a  by aligning the ID tabs  164   a  and  164   e  with the keyways  168 ,  172 . This is followed by inserting contact  156  into cavity  64   b  using ID tabs  164   b  and  164   f  in keyways  178 ,  182 . The second contact  140  is arranged to put ID tabs  164   c  and  164   g  in keyways  168  and  172 , respectively. Finally, contact  152  is inserted into cavity  64   c  with ID tabs  164   d  and  164   h  entering keyways  186 ,  190 . This sequence of inserting the contacts into base member  62  is for illustrative purposes and the contacts  140 ,  156  and  152  may be inserted into base member  62  in any desired order. Once the contacts  140 ,  152  and  156  are in place the insert  80  is positioned over recess  78  with fin  104  of insert  80  aligned with aperture  106  in the base member  62 . In such position the retainers  192 ,  198 ,  192  and  206  enter their associated cavities  64   a ,  64   b,    64   a  and  64   c.  A downward push on the top surface  82  of insert  80  causes the locking tabs  98  to enter their respective slots  100  and engage the underside of lip  102 . The assembly is completed by placing a self-taping screw  108  in aperture  110  of the insert  80  and driving it downwardly with a hammer or the like into aperture  112  of base member  62 . 
     The interior surface  208  of the wall plate  66  has raised ledges  210  about each of the slots  114  and raised ledges  212  about each of the keyhole apertures  122  to prevent over tightening of fasteners which are inserted in slots  114  and keyhole apertures  122  and cracking of the wall plate  66 . 
     FIGS. 11 and 12 show an insert  90  arranged to receive an electrical plug with three flat, straight prongs and a U-shaped ground prong. The third flat, straight prong replacing the L-shaped prong of FIGS. 1 to  10 . The retainer  214  is generally rectangular and has a slot  216  and a top edge  218 . Top edge  218  engages the free end of a contact  140 . The assembly of insert  90  to a body member  62  will be the same as set forth with respect to insert  80 . 
     While there have been shown and described and pointed out the fundamental novel features of the invention as applied to the preferred embodiments, as are presently contemplated for carrying them out, it will be understood that various omissions and substitutions and changes of the form and details of the devices illustrated and in their operation may be made by those skilled in the art, without departing from the spirit of the invention.