Abstract:
Electrical receptacles configured to eliminate arc faults rather than merely detect such faults with attendant circuit disconnection, the invention contemplates low-cost, child-safe electrical receptacles useful in residential situations and which can be fitted within the confines of single gang enclosures. The safety receptacles of the invention can be used in all use situations including both residential and industrial applications to increase safe use of electrical receptacles in residential applications in particular and to decrease industrial liabilities. In essence, the safety receptacles of the invention prevent arcing during insertion of a plug into the receptacle, during residence of the plug in the receptacle and during removal of the plug from the receptacle with a substantial load to the receptacle.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to electrical receptacles configured to prevent dangerous arcing caused by movement of electrical current from its proper path to an improper path with sparking associated with such movement. 
     2. Description of the Prior Art 
     Various causes produce arc faults in electrical receptacles presently used in residential and industrial applications. Dangerous conditions are produced when arc faults occur, the arc being the result of sparking caused by movement of an electrical current from a proper path to an improper path. Recognition of the dangers inherent in the occurrence of arc faults has resulted in requirements in the National Electric Code for installation in appropriate locations of arc-fault circuit interrupting devices. Such devices are to be required especially in residential applications and particularly for bedroom circuits to prevent a major cause of death and injury due to fires caused by arc faults. Even though these arc-fault circuit interrupters are useful devices, it is to be understood that such devices do not fully address the problem of arcing in electrical receptacles since these devices only act to interrupt or disconnect a circuit once an arc is sensed. In other words, these devices do not prevent arc faults but merely disconnect the circuit in which the arc fault occurs on sensing of the arc fault. Since the arc fault still occurs in these prior devices, hazards are not eliminated completely but are simply rendered less likely to progress to a degree capable of causing damage and injury. The need has been long-felt in this art for low-cost electrical receptacles useful in both residential and industrial applications and which are particularly child-safe to prevent electrocution in the event a child or even someone other than a child inadvertently inserts a foreign object into an electrical receptacle with attendant dire consequences. This need in the art has further included the integration of an arc-eliminating structure into receptacles as small as single gang enclosures, thereby to permit realization of the advantages of arc elimination in electrical receptacles of all sizes and configurations. The present invention can be integrated into essentially all such electrical receptacles and configured to prevent arc faults during the time that a plug is inserted into and removed from a receptacle even with a substantial load to the receptacle. 
     SUMMARY OF THE INVENTION 
     The invention is embodied in electrical receptacles of varying type and description, the invention acting to provide low-cost safe receptacles which can be configured as child-proof for home use when integrated into single gang or similar enclosures. The invention can further be embodied in industrial receptacles to decrease the potential for the creation of hazardous conditions whether during normal use of a receptacle or inadvertent entry of extraneous matter into the receptacles such as can cause arcing in conventional receptacles. 
     In the several embodiments of the invention, receptacles are provided with a neutral input connecting to neutral external conductors. The “hot” side of the receptacle is provided with an input having external connectors, this input connecting to a switching device rather than directly to an output receiver “hot” side of a plug. A sensor disposed under the neutral receiver controls the switching device, a circuit thus formed necessarily completing itself before electricity can pass through to the “hot” side of the plug. Arcing associated with connection and disconnection under a high load is thereby eliminated. 
     The several concepts of the invention can be assembled in ways which will be apparent to those skilled in the art. As one example, the sensor can be installed on either the “hot” or groundside of a plug with the intent of the invention being realizable at least to some degree in either instance. A momentary switch is chosen as the switching device and is located at the neutral leg for ease of manufacture and accessibility. Placement of the sensor on the neutral side creates the necessity of having both hot and neutral inserted before an electrical flow can occur, thus eliminating the possibility of an arc and reducing the possibility of shock or electrocution to anyone inserting an electrically conductive material into the hot side of the plug. A neutral side sensor senses the presence of the prong of the plug and provides a contact closure which, in turn, allows an electrical flow through an energizer coil of a relay. The relay thus energizes and high-rated volt amp contacts allow a completion of the circuit where electrical flow to the “hot” side of the plug is established. A Quencharc circuit is disposed between the contacts to act as a fast-acting suppressor to remove arc associated with switching under load. 
     Accordingly it is a primary object of the invention to provide electrical receptacles configured to eliminate arc faults rather than merely detect arcing after arc initiation. 
     It is another object of the invention to provide electrical receptacles capable of residential and industrial use and configured to fit the volumetric confines of even a single gang enclosure and which acts to eliminate arc faults. 
     It is a further object of the invention to provide low-cost and safe electrical receptacles capable of eliminating arc faults during insertion into and removal of a plug from such receptacles when the receptacle is under a substantial load. 
     Further objects and advantages of the invention will become more apparent in light of the following detailed description of the preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an idealized perspective view of an electrical receptacle configured according to the invention; 
     FIG. 2 is an elevational view of the receptacle of FIG. 1 with portions of the receptacle shown in exploded relation to other portions of the receptacle; 
     FIG. 3 is a plan view of the receptacle of FIG. 1; 
     FIG. 4 is a side elevational view of the receptacle of FIG. 1; 
     FIG. 5 is an exploded side elevational view of the receptacle of FIG. 1; 
     FIG. 6 is a schematic plan view of a portion of the receptacle with upper components removed; 
     FIG. 7 is a schematic side elevational view; 
     FIG. 8 is a detailed schematic of the receptacle; and, 
     FIG. 9 is a simplified schematic of an electrical receptacle configured according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings and particularly to FIGS. 1 through 3 which are idealized illustrations of the structure of a preferred embodiment of the invention and with further reference to FIGS. 4 through 7 which respectively show the structures of FIGS. 1 through 3 as idealized illustrations in FIGS. 4 and 5 and as schematic elevations in FIGS. 6 and 7, an electrical receptacle is seen to be subject to a load at least when a plug  1  resides conventionally in the receptacle  10 , the load being applied in a conventional manner. The details of the load and of the plug  11  are not illustrated herein for convenience. The plug  11  is conventionally formed with hot, neutral and ground contacts respectively designated as hot contact  12 , neutral contact  13  and ground contact  14 . The receptacle  10  is provided with sockets  15  such as are conventionally provided in standard electrical receptacles and which are typically formed of a hard plastic according to Underwriters Laboratory ratings. The sockets  15  are conventionally provided with slots  16  and  17  configured according to standard practice in the art to respectively receive the hot contact  12  and the neutral contact  13  of the plug  11 . Aperture  18  is conventionally provided to receive the ground contact  14  of the plug  11 . Hot and neutral contact receivers  19  and  20  are disposed beneath the sockets  15  for electrically contacting in a conventional manner the contacts  12  and  13  respectively of the plug  11 . The contact receivers  19  and  20  are best seen in FIGS. 4 and 5. The contacts  12 ,  13  and  14  as well as the contact receivers  19  and  20  are preferably formed of brass or copper according to Underwriters Laboratory ratings and are standard in electrical receptacles. 
     The receptacle  10  is provided with a mounting plate  23  having wing extensions  21  such as is conventional in the art for mounting of the receptacle  10  in a recessed position in a wall (not shown) or the like. Apertures  22  formed in the wing extensions  21  allow use of screws or similar fasteners to mount the receptacle  10  in a conventional manner. 
     In view of the foregoing, each of the sockets  15  can be said to be provided with one neutral contact receiver such as the receiver  20  and one hot contact receiver such as the receiver  19 , the receivers  19 ,  20  being contacted respectively by the contacts  12 ,  13  of the plug  11  through the slots  16 ,  17  respectively. The sockets  15  are substantially standard at least as to the inclusion of the slots  16 ,  17 , said slots  16 ,  17  providing entry into the socket  15  through which the contacts  12 ,  13  of a conventional plug such as the plug  11  are inserted to gain access to electrical power through the electrical receptacle  10 . Ground within the receptacle  10  is provided in a conventional manner as at  50  by means of a conductive path from the aperture  22  to grounding. Such an expedient can be provided with a short length of conductive wire or the like which is held to ground by means of a screw and need not be described in detail herein. 
     Receptacle body  28  of substantially conventional design mounts the plate  23  and thus the sockets  15  as well as the hot and neutral contact receivers  19 ,  20 . External neutral conductor plates  30  which essentially comprise externally disposed portions of the conductive material forming the neutral receivers  20  are mounted by screws  32  to the receptacle body  28  in a substantially conventional fashion except that the plates are typically connected together in a standard receptacle. In the present receptacle  10 , the plates  30  are not electrically or mechanically joined together so that the sockets  15  are isolated electrically from each other. The “hot” side of the receptacle body  28  is similarly configured with hot conductor plates  34  particularly being separate and held to the receptacle body  28  by means of screws  36 . 
     Each of the sockets  15  are provided with momentary switches  38  which are housed within the receptacle body  28 , FIGS. 1 and 2 only showing one of the switches  38  for ease of illustration. Switch actuator pin  40  is disposed in alignment with the neutral contact receiver  20  and is pushed downwardly to actuate the switch  38  on insertion of the neutral contact  13  into the slot  17  in the socket  15 . The presence of the plug  11  inserted into one of the sockets  15  is thus “sensed” by the switch actuator pin  40  to actuate the switch  38  to function in concert with one of the relays  42  to which the switch  38  is electrically connected. It is to be understood that each socket  15  is provided with one of the switches  38  and one of the relays  42  and that each socket  15  functions independently. 
     The relays  42  are mounted one each to the receptacle body  28  on opposite sides of the body  28  from each of the sockets  15 . As is conventional in the art, each relay  42  is provided with coils (not shown) connected electrically to pins  43 ,  44 . Each of the relays  42  is provided with a common terminal at pin  45  while terminal pins  46 ,  47  are also provided on each relay  42 . Pin  43  is connected electrically to the neutral input of the receptacle  10  such as through the screws  32  which mount the neutral conductor plates  30  to the receptacle body  28 . Pin  44  electrically joins to switch pin  48  of the switch  38  while the common terminal pin  45  electrically connects to switch pin  49  of the switch  38 . Line hot input is made to the switch pin  49  of the switch  38  and to the common terminal pin  45  of the relay  42  through the AC source. The switch pin  47  is connected electrically to the “hot” side of the receptacle body  28  through one each of the screws  36  which hold the hot connector plates  34  to the receptacle body. 
     As can be seen in FIG. 3, the tips of the switch actuator pins  40  can be seen through the slots  17  of the sockets  15  while conventional electrical contact structure associated with the hot conductor plates  40  can be seen through the slots  16  of the sockets  15 . Insertion of the plug  11  into one of the sockets  15  as best seen in FIG. 5 causes the switch actuator pin  40  to be depressed and thus to actuate the switch  38 . Closure of the switch  38  allows voltage to energize the coils (not shown) of the relay  42  from the output of the hot line input on pin  48  of the switch  38 . When the coil (not shown) of the relay  42  is energized, the common terminal pin  45  and the relay  42  connects to the terminal pin  47  of the relay, thereby allowing line hot input from the common terminal pin  45  to flow out of the pin terminal  47  of the relay  42  to the hot side of the receptacle  10 . 
     When the switch  38  is open, that is, the plug  11  is not sensed by the switch  38 , the coil (not shown) of the relay  42  will not be energized and the common terminal pin  45  of the relay  42  will be connected to the terminal pin  46  of the relay  42 , which pin  46  has nothing electrically connected to it. Voltage will therefore not be present at either the hot side or the terminal pin  47  of the relay  42 . 
     Referring further now to FIGS. 6 and 7, a general description of the invention can be provided for additional reference to the manner by which the invention finds utility in a variety of applications and with conventional structure. As an example, a “neutral” input can be provided by connection to either screw or mechanical neutral external connectors conventionally provided on a plug such as the plug  11 . As can also be readily seen, the “hot” side of the receptacle  10  communicates through the hot contact receiver  19  of each of the sockets  15 , input being through external connectors which can be either screw or mechanical fasteners as is known to be conventional in the art. The circuitry thus provided herein assures that a circuit which is to be formed by insertion of contacts of a plug into the receptacle  10  must complete itself before electricity is allowed to pass through to the “hot” side of the plug, thereby eliminating arcing associated with connecting and disconnecting of a plug with the receptacle  10  under a high load. 
     The hot contact  12  of the plug  11  will pass through to a load without interference from the receptacle  10  of the invention. The neutral contact  13  of the plug  11  will pass through the switch  38  which is controlled by the actuator pin  40  from the neutral side of the receptacle  10 . Ground will pass through the receptacle  10  to a load as a safety ground in a conventional manner which meets all Underwriters Laboratory rating requirements. 
     The contacts  12 ,  13  of the plug  11  respectively make contact with the electrical contact receivers  19 ,  20  without electrical flow occurring. After the contacts  12 ,  13  are inserted all the way into the receptacle  10  and contact has been established to the electrical contact receivers  19 ,  20 , the actuator pin  40  senses the presence of the plug  11  and signals the switch  38  to provide the switching function which permits electrical flow through the circuit. The moment the plug begins to be removed from the receptacle  10 , the actuator pin  40  signals the switch  38  such that the switch  38  produces a switching function to disconnect electrical flow prior to the contacts  12 ,  13  leaving the electrical contact receivers  19 ,  20 , thereby eliminating any arc at the receivers  19 ,  20 . 
     The switch  38  is preferably located on the neutral side of the receptacle  10 , and can take the form of a number of different sensing devices and can be placed within the receptacle  10  in a number of locations to provide the necessary function. A switch preferably employed takes the form of a 0.5A momentary switch which is mounted under the neutral input electrical contact receiver  20  in concert with the actuator pin  40  which protrudes above the base of the receiver  20 . When the contacts  12 ,  13  of the plug  11  are inserted into the receptacle  10 , the neutral contact  13  comes into contact with the actuator pin  40  and “signals” the switch  38  to operate if the plug  11  is fully inserted into one of the sockets  15  of the receptacle  10 . A momentary switch such as can conveniently be employed is formed of hard plastic and has electrical contactors which can be formed of a conductive material capable of passing Underwriters Laboratory ratings for high voltage, low amperage implementation. The actuator pin  40  is preferably formed of a non-conductive hard plastic and is the mechanism for establishment of contact with the inserted neutral contact  13  of the plug  11  on the neutral side. The travel and normally open NO and normally closed NC positions at  50  and  52  respectively can vary according to particular design, the circuit so disclosed being also seen in FIGS. 8 and 9 as will be referenced relative to the following discussion in addition to the drawings referred to above. Since the actuator pin  40  is formed of a non-conductive material, the receptacle “hot” is not present when the plug  11  is not present. If a metallic conductor is inserted on the hot side of the receptacle  10  and the actuator pin  40  does not sense the presence of a plug contact on the neutral side, then voltage is not present in the receptacle  10 . Risk of shock is thereby greatly reduced and arc associated with the connection and disconnection of a load is essentially eliminated. In the event that a metallic conductor is inserted in both of the sockets  15  of the receptacle  10  and are tied together, a closed short will occur and will trip a conventional breaker used as a safety device in a conventional manner for the receptacle  10 . However, in no event shall an arc occur at the receptacle  10 . 
     The relays  42  preferably take the form of  15 A relays which are electrically connected to the switch  38 . Such relays can have any number of pins. The five-pin relay shown in the drawings as the relay  42  has a fifth pin which can be used to operate a signal generator such as a light source or an auditory source which would provide an audible signal. The relay  42  provides a contact opening and closure according to the position of the switch  38 , that is, the momentary switch in a preferred embodiment. It is to be understood that a number of different devices are known in the art which can be used to provide an open or closed circuit, such devices including conventional triacs, transistors and the like. However, the relay  42  as shown provides optimum cost and size solutions as the circuit element choice for the switching function. 
     When the plug  11  is inserted into the receptacle  10 , the neutral contactor side of the receptacle as noted above senses the presence of the neutral contact  13  of the plug  11  through operation of the momentary switch  38 . The normally open NO position of the switch  38  then switches to closed and provides a voltage through an energizer coil (not shown) of the relay  42 . When the NO relay coil is energized, the relay  42  switches contactors to a closed position and provides power to the receptacle, thereby eliminating any arc at the receptacle  10 . As noted in the drawings, this condition allows power to be on only when the momentary switch  38  senses the presence of neutral contact  13  of the plug  11  when inserted into the receptacle  10 . When the contact  13  is not sensed, the momentary switch  38  does not sense the presence of a contact and power is not introduced to the receptacle  10  through a load. Accordingly, power is not introduced into the receptacle  10  until the presence of a contact is sensed by the switch  38 . 
     It is to be understood that the invention can be configured other than as explicitly described herein, the scope of the invention being defined by the definitions provided by the appended claims.