Abstract:
A ground-fault circuit interrupter (GFCI) power receptacle with reverse wiring protection. The GFCI power receptacle has a circuit board assembled in a housing; a pair of resilient movable conducting arms attached to the circuit board, each having a movable contacts at its free end, a pair of stationary conducting arms each having a stationary contact at one end, and a pair of output face terminals each having a contact. The movable contacts can contact the stationary contacts and the output face terminal contacts to establish electrical connection between the input and output terminals of the power receptacle. The power receptacle has a simple structure where one movable contact can connect or disconnect the load in various working conditions, which can be used in various types of power receptacles.

Description:
[0001]    This application claims foreign priority benefits under 35 U.S.C. §119(a)-(d) from China Patent Application No. 200820153762.5, filed Oct. 7, 2008, which is incorporated by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to a power receptacle with ground-fault circuit interrupter (GFCI) functions, and in particular, it relates to a GFCI receptacle with reverse wiring protection function. 
         [0004]    2. Description of the Related Art 
         [0005]    Power receptacle with ground-fault circuit interrupter (GFCI) functions are widely uses in daily life for electrical appliances. Such receptacles provide protection that ensures the proper function of electrical appliances and safety of users. 
         [0006]    In most conventional GFCI receptacles, the connection or disconnection between the input terminals and output terminals of a power receptacle relies on the resilient nature of the resilient moveable conducting arms. However, the uniformity of the resilience of the moving arms is difficult to control during manufacturing, and cannot be completely tested using destructive test. Therefore, if a moving arm is defective in its resilience or losing its resilience after the receptacle has been use for a long period of time, then there may be a misalignment between the electrical contact of the movable conducting arm and the corresponding electrical contact of the stationary conducting arm. This may make the electrical connection of the power receptacle unreliable. In some cases it may cause the loss of the ground fault protection functionality of the power receptacle. More seriously, if the load side experiences an ultra-low ground fault (e.g. over 1,000 A of leakage current), arcs may occur when the electrical contacts of the movable and stationary conducting arms are disconnecting, which may melt the contacts and fuse them together. Thus, even though the disconnect mechanism of the GFCI may still be functional, the contacts are in fact not disconnected. This presents great hidden danger to safety to the users who are not aware of the faulty condition of the power receptacle. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is directed to a GFCI power receptacle with improved safety features. 
         [0008]    An object of the present invention is to provide a GFCI with reverse wiring protection function which can correctly connect or disconnect the load in any conditions, and more particularly can automatically and quickly disconnect leakage current when a ground fault condition is present. 
         [0009]    Additional features and advantages of the invention will be set forth in the descriptions that follow and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings. 
         [0010]    To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention provides a GFCI power receptacle with reverse wiring protection function, which includes a housing, a circuit board enclosed in the housing, a pair of resilient movable conducting arms attached to the circuit board, a pair of stationary conducting arms, and a circuit interrupter mechanism with circuit interrupter, locking mechanism and electromagnetic element. Also installed in the housing are reset mechanism, test mechanism, and a pair of output receptacle face terminals with electrical contacts. The stationary arms each has an electrical contact at one end, and moving arms each also has an electrical contact at its moving end. The contacts of the moving arms can close on to the contacts of the stationary arms and the face terminals to connect power between the input and output sides of the power receptacle. The power receptacle also provides an improved interrupter mechanism where the interrupter block is located underneath the movable conducting arms, with lifting arms extending from opposite sides of the interrupter block, and a pressing plate located above the movable conducting arms that corresponds with the interrupter block, and a spring disposed above the pressing plate. 
         [0011]    In a preferred embodiment, the movable conducting arms are connected to the input terminals of the power receptacle and the stationary conducting arms are connected to the output load terminals of the power receptacle. 
         [0012]    In another preferred embodiment, the movable conducting arms are connected to the output terminals of the power receptacle and the stationary conducting arms are connected to the input terminals of the power receptacle. 
         [0013]    Selectively, at least one of the movable contacts may connect to or disconnect from at least one of the stationary contacts or face terminal contacts to open or close a neutral power line. 
         [0014]    Also selectively, at least one of the movable contacts may connect to or disconnect from at least one of the stationary contacts or face terminal contacts to open or close a hot power line. 
         [0015]    Additionally, at least one of the movable contacts may connect to or disconnect from at least one of the stationary contacts or face contacts to open or close the natural line of the face terminals and the down-stream load terminals. 
         [0016]    Alternatively, at least one of the movable contacts may connect to or disconnect from at least one of the stationary contacts or face terminal contacts to open or close the hot line of the face terminals and the down-stream load terminals. 
         [0017]    In one preferred embodiment, the circuit interrupter block is located underneath the resilient movable conducting arms, with lifting arms extending from opposite sides of the interrupter block, and a pressing plate located above the movable conducting arms that corresponds with the interrupter, and a spring disposed above the pressing plate. 
         [0018]    Preferably, the pressing plate has a concave lower surface facing the corresponding lifting arms of the interrupter block. Optionally, the upper surface of the side lifting arms also has a concave shape. Preferably, the concave lower surface of the pressing plate and the concave upper surface of the side lifting arms have a cylindrical shape. 
         [0019]    Moreover, the interrupter mechanism includes a supplementary switch disposed below the interrupter block and installed on the circuit board. The supplementary switch has a supplementary moving conducting arm and a supplementary stationary conducting arm with corresponding electrical contacts. 
         [0020]    In addition, the pressing plate has two supplementary arms on a side facing the corresponding side lifting arms of the interrupter block, the supplementary arms extending beyond the side lifting arms of the interrupter block to a location adjacent the supplementary moveable conducting arm of the supplementary switch. 
         [0021]    The reset mechanism of the GFCI receptacle includes a reset button, a reset shaft attached to the reset button, and a reset spring disposed around the reset shaft. The reset shaft passes through a through hole on the pressing plate, a through hole on the interrupter block and a through hole of the locking member. The interrupter spring is also disposed around the reset shaft below the reset spring. 
         [0022]    Preferably, the interrupter spring is separated from the reset spring. 
         [0023]    The GFCI receptacle further includes an arc blocking plate disposed between the circuit board and the pair of input conducting arms to block arcs generated when the contacts of the conducting arms are separating from each other. The arc blocking plate may be made of an arc-resistant material, such as PVC, GPO-3 laminated boards, etc. 
         [0024]    The present invention has many advantages over conventional technologies. First, the new GFCI receptacle of the present invention has a simple structure and is low cost to produce. It can be effectively used to connect or disconnect load in various working conditions, and can be used in various types of power receptacles. 
         [0025]    Second, the new GFFCI receptacle of the present invention is safe and reliable, and easy to use. It can effect the connection or disconnection between the corresponding movable contacts and the stationary contacts simultaneously, to not only prevent fusing of the contacts caused by large local current but also accident caused by mistakes in operation. 
         [0026]    Third, the new GFCI receptacle of the present invention has additional pressing plate that corresponds with interrupter spring which effectively increases the engagement between the interrupter block and the movable conducting arms. 
         [0027]    Fourth, the new GFCI receptacle of the present invention utilizes a supplemental switch disposed below the interrupter block and mounted on the circuit board, which disconnects the GFCI circuit in the event of a current leakage to prevent damage to the sensing coil by a large current flowing through the device for a long period of time. 
         [0028]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    The features and advantages of the preferred embodiments can be further understood from the detailed description below with reference to the following drawings: 
           [0030]      FIG. 1  is an exploded perspective view of a GFCI according to an embodiment of the present invention. 
           [0031]      FIG. 2  is an exploded view of the interrupter mechanism of the GFCI of  FIG. 1  including the new moveable conducting arms. 
           [0032]      FIG. 3  is a perspective view of the components in  FIG. 2  mounted on the circuit board. 
           [0033]      FIG. 4  is a cross-sectional view of the GFCI of  FIG. 1  in a reset state. 
           [0034]      FIG. 5  is perspective view of a portion of the GFCI of  FIG. 1  in the reset state, showing the various contact arms. 
           [0035]      FIG. 6  is a cross-sectional view of the GFCI of  FIG. 1  in a tripped state. 
           [0036]      FIG. 7  is a circuit diagram of the GFCI of  FIG. 1 . 
           [0037]      FIG. 8  is an exploded perspective view of a GFCI according to another embodiment of the present invention. 
           [0038]      FIG. 9  is a view showing various components of the GFCI of  FIG. 8  mounted on the circuit board. 
           [0039]      FIG. 10  is a cross-sectional view of the GFCI of  FIG. 8  in a reset state. 
           [0040]      FIG. 11  is perspective view of a portion of the GFCI of  FIG. 8  in the reset state, showing the various contact arms. 
           [0041]      FIG. 12  is a cross-sectional view of the GFCI of  FIG. 8  in a tripped state. 
           [0042]      FIG. 13  is a circuit diagram of the GFCI of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0043]    The following numerals are used in the drawing:
         1 : Top cover     2 ,  3 : Tamper resistant mechanism     4 : Reset button     5 : Reset shaft     51 : Locking slot     6 : Test button     7 : Grounding frame assembly     71 ,  72 : Grounding plates     8 : Interrupter spring     9 : Interrupter pressing plate     91 ,  92 : Side lifting Arms of the pressing plate     93 ,  94 : Concave surfaces of the pressing plate     10 ,  11 : Moveable conducting arms     101 ,  111 : moveable contacts     12 : Locking member     121 : Through hole of the locking member     13 : Interrupter block     131 ,  132 : Side arms of the interrupter block     133 ,  134 : Slots on the side arms of the interrupter block     14 : Spring for the interrupter plunger     15 : Interrupter plunger     16 : Interrupter spring frame     161 : Interrupter coil spring     17 : Supplementary moveable conducting arm     171 : Supplementary moveable contacts     18 : Supplementary stationary conducting arm     181 : Supplementary stationary contacts     19 : Middle support frame     20 ,  21 : Output face terminals of the receptacle     201 ,  211 : face terminal contacts     202 ,  212 : Metal plates of the output face terminals     22 : Reset spring     23 : Test plate     24 : Circuit board     25 : Reset switch     251 : Moveable contact of the reset switch     252 : Stationary contact of the reset switch     26 : Electromagnetic ring assembly     27 ,  28 : Stationary conducting arms     271 ,  281 : Stationary contacts     29 : Base frame     30 ,  31 : Output load terminals of the receptacle     32 ,  33 : Input terminals of the receptacle     34 : Screws       
 
         [0088]      FIGS. 1-7  illustrate the structure of a GFCI receptacle according to one embodiment of the present invention.  FIGS. 8-13  illustrate the structure of a GFCI receptacle according to another embodiment of the present invention. 
         [0089]    Referring to  FIGS. 1-3 , the following are provided within a body formed by a top cover  1  and a base frame  29 : a middle support frame  19 , a grounding frame assembly  7 , and a circuit board  24  disposed between the middle support frame  19  and the base frame  29 . The circuit board  24  has a pair of resilient moveable conducting arms  10 ,  11 , a pair of stationary conducting arms  27 ,  28 , and an interrupter assembly that includes an interrupter block  13 , a locking member  12  and electromagnetic components. 
         [0090]    The pair of stationary conducting arms  27 ,  28  are input conducting arms, with their one ends inserted into the electromagnetic ring assembly  26 , while their other ends are provided with input stationary contacts  271 ,  281 . The pair of moveable conducting arms  10 ,  11  are output conducting arms, and include resilient metal plates where the free ends of the resilient metal plates are provided with moveable contacts  101 ,  111 . On two sides of the middle support frame  19  are output face terminals  20  and  21 , which are provided with metal plates  202 ,  212  aligned with corresponding plug holes on the top cover  1 , as well as face terminal contacts  201 ,  211 . Further, grounding plates  71  and  72  are provided on the grounding frame assembly  7 , which are coupled to the ground legs and aligned with corresponding plug holes on the top cover  1 . The interrupter block  13  is disposed below the pair of moveable conducting arms  10 ,  11 . The interrupter block  13  has two side lifting arms  131 ,  132  extending outwardly. Above the moveable conducting arms  10 ,  11  is a pressing plate  9  that cooperates with the interrupter block  13 . An interrupter spring  8  is fixedly attached to the pressing plate  9  at its top. 
         [0091]    As seen in  FIGS. 1-3 , in the preferred embodiment, the structure of pressing plate  9  is an elongated plate shape that corresponds to the shape of the interrupter block  13 . It should be understood that any suitable structure of the pressing plate  9  may be used so long as it can cooperate with the interrupter block  13  to provide a backing force for the moveable conducting arms  10 ,  11 . The bottom side of the pressing plate  9  may be provided with concave surfaces  93 ,  94 , and the top side of the side arms  131 ,  132  of the interrupter block  13  may also be provided with concave surfaces in order to enhance the sensitivity of pinching action upon the moveable conducting arms  10 ,  11 . Further, the bottom of the pressing plate  9  has U-shaped arms  91 ,  92  extending downwardly, which are positioned to be around the side lifting arms  131 ,  132  of the interrupter block  13  to help the cooperation of the pressing plate  9  and the interrupter block  13 . One branch of the U-shaped arms  91 ,  92  are coupled to the interrupter block  13  by fitting into slots  133 ,  134  on the side lifting arms  131 ,  132 ; the other branch of the U-shaped arms  91 ,  92  extend beyond the side lifting arms  131 ,  132  to contact a supplementary moveable conducting arm  17  of a supplementary switch. The supplementary switch, which is mounted on the circuit board  24 , has a supplementary stationary conducting arm  18  corresponding to the supplementary moveable conducting arm  17 , with a supplementary moveable contact  171  and a supplementary stationary contact  181  on the arms  17  and  18 , respectively. 
         [0092]    On the pressing plate  9 , the interrupter block  13  and the locking member  12 , through holes are provided for the reset shaft  5  to pass through. The reset shaft  5  is attached to the reset button  4  and has a reset spring  22  around it. The interrupter spring  8  is disposed above the pressing plate  9 , in a sleeve that extends coaxially above the through hole. In is understood that the interrupter spring  8  may be coupled the pressing plate  9  in other suitable ways, such as fixedly soldered. To more reliably couple the pressing plate  9  and the interrupter block  13 , another sleeve may be formed on the interrupter block  13  extending coaxially above the through hole and inserted into the through hole of the pressing plate  9 . The coupling of the pressing plate  9  and the interrupter block  13  is not limited to the structures described here. Also, the interrupter spring  8  may be disposed around the reset shaft  5 , separated from the reset spring  22 , as shown in  FIGS. 4 and 6 . 
         [0093]      FIG. 4  illustrates the GFCI receptacle in a normally functioning, reset condition. When the reset button  4  is pressed down, the reset shaft moves downward and compresses the reset spring  22 . At the same time, the pressing plate  9  and the interrupter block  13  move downward, so that the moveable contact  251  and the stationary contact  252  of the reset switch  25  contact each other. The closing of the reset switch  25  causes a current through the disconnecting coil  161 , and the magnetic field of the coil  161  causes the plunger  15  to move. The locking member  12  moves with the plunger  15 , and the locking slot  51  of the reset shaft  5  passes through the hole  121  of the locking member  12 . Then, the reset switch  25  automatically disconnects due to its resilience, and the coil  161  is de-energized. As a result, the plunger  15  moves back due to the biasing force of the spring  14 , bringing the locking member  12  with it, causing the locking slot  51  of the reset shaft  5  to engage the locking member  12  and lock the reset shaft  5 . Then, when the pressing force on the reset button is released, the reset spring  22  urges the reset shaft  5  to move upwards. At this time, because the reset shaft  5  is locked with the locking member  12 , the reset shaft  5  brings the locking member  12 , the interrupter block  13  and the pressing plate  9  upwards. The side lifting arms  131 ,  132  of the interrupter block  13  pushes the output moveable conducting arms  10 ,  11  upwards, causing the output moveable contacts  101 ,  111  to come in contact with input stationary contacts  271 ,  281  as well as output face terminal contacts  201 ,  211  of the output face terminals  20 ,  21 . As a result, the input side and the output side of the receptacle are electrically connected, as shown in  FIG. 5 . It should be noted that the arms  91 ,  92  of the pressing plate  9  are in contact with the supplementary moveable conducting arm  17  before reset; after reset, because the arms  91 ,  92  of the pressing plate  9  move upwards, the supplementary moveable contact  171  and the supplementary stationary contact  181  come into contact with each other, which closes the supplementary switch  17 / 18 . 
         [0094]    When current leakage occurs within the receptacle, as shown in  FIG. 6 , the electromagnetic ring assembly detects the leakage and generates an electromagnetic field in the disconnecting coil  161 . The disconnecting plunger  15  pushes the locking member  12  to move, so that the locking slot  51  of the reset shaft  5  escapes from the through hole  121  of the locking member  12  and moves upwards by the force of the reset spring  22 . As a result, the pressing plate  9  and the interrupter block  13  falls downwards. The interrupter spring  8 , which has been previously compressed by the pressing plate  9 , forces the pressing plate  9  to move downwardly quickly. The pressing plate  9  pushes the output moveable conducting arms  10 ,  11  downwardly, causing the output moveable contacts  101 ,  111  to be separated from the input stationary contacts  271 ,  281  as well as the output face terminal contacts  201 ,  211  of the output face terminals  20 ,  21 . As a result, the electrical connection between input side and the output side of the receptacle is quickly disconnected. Also, because the pressing plate  9  moves downwards quickly, the arms  91 ,  92  of the pressing plate  9  re-establishes contact with the supplementary moveable conducting arm  17  and presses it down, the supplementary moveable conducting terminal  171  is separated from the supplementary stationary conducting terminal  181 . 
         [0095]    Comparing to the separate contacts in existing technologies, the increase surface areas of movable contacts  101 ,  111  will reduce the possible electrical arc and prevent the damage to the contacts by the possible arc. In addition, by the action of the interrupter mechanism, the movable contacts are simultaneously disconnected from the stationary contacts and the face terminal contacts, effectively prevent large current between the contacts. 
         [0096]    The new GFCI also provides a test plate  23  between the output terminal  21  and the test button  6  to form a testing mechanism, to test whether the circuit interrupter is functioning properly through a simulated leakage current circuit. Further, tamper resistance devices  2  and  3  may be provided between the top cover  1  and the grounding frame assembly  7 . Output load terminals  30 ,  31  and input terminals  32 ,  33  of the receptacle are located on both sides of the base frame  29 . Finally, screws  34  fasten the top cover  1 , the middle support frame  19  and the base frame  29  together to form the assembled receptacle. 
         [0097]    According to the circuit diagram shown in  FIG. 7 , it can be seen and understood, when reset the connection between the input contacts and the output contacts will effect the power connection between the LINE side and LOAD side of the receptacle. At least one of the movable contacts may connect to or disconnect from at least one of the stationary contacts or face terminal contacts to open or close a neutral (WHITE) power line, and at least one of the movable contacts may connect to or disconnect from at least one of the stationary contacts or face terminal contacts to open or close a HOT power line. 
         [0098]    In addition, in the GFCI of the present invention, at least one of the movable contacts may connect to or disconnect from at least one of the stationary contacts or face terminal contacts to open or close the natural (WHITE) line of the face terminals and the down-stream load terminals, and at least one of the movable contacts may connect to or disconnect from at least one of the stationary contacts or face terminal contacts to open or close the hot line of the face terminals and the down-stream load terminals. 
         [0099]    In the other embodiment shown in  FIGS. 8-13 , the conducting arms  10 ,  11  attached to the electromagnetic assembly  26  are resilient movable arms, which are connected to the input side of the power receptacle, whereas the conducting arms  27 ,  28  are stationary arms connected to the output side of the power receptacle. In this embodiment, the reset and tripping operations are similar to those of the embodiment described above in connection with  FIGS. 1-7 . 
         [0100]    Referring to  FIGS. 10-12  now, wherein  FIG. 10  shows the GFCI in reset state. Because of the operation of the interrupter block  13 , movable contacts  101 ,  111  are connected with the stationary contacts  271 ,  281  and output face terminal contacts  201 ,  211  respectively, effecting the power connection between the input and output sides of the power receptacle, as shown in  FIG. 11 . As the same time, the supplementary stationary and movable contacts  181 ,  171  of the supplementary conducting arms  17 ,  18  of the supplementary switch are also connected. In the disconnected status as shown in  FIG. 12 , the output movable conducting arms  10 ,  11  are promptly pressed down by the pressing plate  9 , causing disconnection between movable contacts  101 ,  111  and the stationary contacts  271 ,  281  and output face terminal contacts  201 ,  211  respectively. At the same time, the downward movement of the pressing plate  9  also causes the disconnection of the supplementary stationary and movable contacts  181 ,  171 . 
         [0101]    Similarly, from the circuit diagram shown in  FIG. 13 , in the present invention GFCI, at least one movable conducting arm can effect the connection or disconnection of input neutral (WHITE) line or input hot line, and of the neutral (WHITE) line or hot line of the face terminal or output terminal. Therefore, the movable conducting arm design of the present invention GFCI can effectively avoid the drawbacks from internal connection defect or failure and also quickly disconnect power to the face terminals and down-stream load terminals of the receptacle upon the occurrence of a ground fault or other incident, to ensure the safe use of electrical power. 
         [0102]    It will be apparent to those skilled in the art that various modification and variations can be made in the power receptacle of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover modifications and variations that come within the scope of the appended claims and their equivalents.