Patent Publication Number: US-2023155329-A1

Title: Shallow electrical protection device (gfci, afci, and afci/gfci) system and method

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority to U.S. Pat. Application No. 17/698,690, filed Mar. 18, 2022, which claims priority to, and is a divisional of, U.S. Pat. Application No. 16/212,141, filed Dec. 6, 2018, which claims priority to U.S. Provisional Pat. Application No. 62/595,760, filed Dec. 7, 2017, the entire contents of both of which are expressly incorporated herein by reference. 
     This application contains subject matter related to subject matter contained in U.S. Pat. No. 8,830,015 B2 entitled, “COMPACT LATCHING MECHANISM FOR SWITCHED ELECTRICAL DEVICE,” by Kenny Padro et al., which is assigned to the assignee hereof, and the entire contents of which are expressly incorporated herein by reference. 
    
    
     FIELD 
     Embodiments relate to switched electrical devices, more particularly to circuit interrupting devices. 
     SUMMARY 
     Circuit interrupting devices, such as ground fault circuit interrupter (GFCI) devices, switch to a “tripped” or unlatched state from a “reset” or latched state when one or more conditions is detected. GFCI devices having contacts that are biased toward the open position require a latching mechanism for setting and holding the contacts in a closed position. Likewise, switched electrical devices having contacts that are biased toward the closed position require a latching mechanism for setting and holding the contacts in an open position. Examples of conventional types of devices include devices of the circuit interrupting type, such as circuit breakers, arc fault interrupters, and GFCIs, to name a few. 
     Many electrical receptacles have built-in ground fault protection circuitry, i.e., GFCI receptacles. Such protection circuitry and the associated mechanisms normally take up a substantial amount of the physical space within a receptacle housing, the size of which is limited by the standard junction boxes in which they must fit. The embodiments disclosed in the present application attempt to solve these problems by providing more compact devices, allowing for shallower receptacles and more space for other elements and/or features. 
     One embodiment discloses an electrical outlet receptacle comprises a housing including a face plate and a plurality of sensing cores each configured to receive a current flow through a center cavity. The current flow defines a current flow direction through the center cavity, wherein the current flow direction is parallel to the face plate, and the plurality of sensing cores are placed symmetrically in a translational direction across the electrical outlet receptacle. 
     Another embodiment discloses an electrical outlet receptacle comprises a housing including a face plate and a sensing core configured to receive a current flow through a center cavity. The current flow defines a current flow direction through the center cavity of the sensing core, wherein the current flow direction is parallel to the face plate. 
     Another embodiment discloses an electrical outlet receptacle comprises a circuit board defining a first plane, a set of fixed contacts, a set of movable contacts, a solenoid having a central axis perpendicular to the first plane, a carriage movable axially along the solenoid and configured to interact with the set of movable contacts, a lifting shelf slidably coupled to a slot in the carriage and movable in a translational direction perpendicular to the central axis of the solenoid, a slide mechanism coupled to the lifting shelf and movable in the translational direction of the lifting shelf, a reset plunger with a portion extending through a first end of the solenoid and axially movable therein, and an armature movable axially along the portion of the reset plunger extending through the solenoid. The circuit board includes at least one contact pad. The solenoid includes a second end opposite the first end. The carriage is adapted to advance the set of movable contacts to form electrical communication with the set of fixed contacts during resetting of the electrical outlet receptacle. The lifting shelf includes a latching portion. The slide mechanism includes a cam surface to transform a downward force to a translational force applied to the coupled lifting shelf. The reset plunger includes an intermediate collar configured to engage to the latching portion of the lifting shelf. The armature includes a slanted projection configured to contact the cam surface of the slide mechanism and provide the downward force on the cam surface. 
     Other aspects of the application will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The aspects and features of various exemplary embodiments will be more apparent from the description of those exemplary embodiments taken with reference to the accompanying drawings, in which: 
         FIG.  1    is a front perspective view of a receptacle incorporating the resettable switching apparatus of the application; 
         FIG.  2    is a front perspective view of the receptacle of  FIG.  1   , with the front and rear covers and tamper-resistant mechanisms removed; 
         FIG.  3    is a front perspective view showing a configuration of a set of movable contacts and a set of fixed contacts according to one embodiment; 
         FIG.  4 A  is a front perspective view of the carrier assembly of the receptacle according to one embodiment; 
         FIG.  4 B  is a front perspective view of the carrier assembly of the receptacle according to another embodiment; 
         FIG.  5 A  is a front perspective view of the core assembly of the receptacle; 
         FIG.  5 B  is a front perspective view showing a configuration of a sense transformer core according to one embodiment; 
         FIG.  5 C  is a front perspective view showing a configuration of a sense transformer core according to another embodiment; 
         FIG.  6 A  is a side perspective view of the core assembly of the receptacle according to one embodiment; 
         FIG.  6 B  is a side perspective view of the core assembly of the receptacle according to another embodiment; 
         FIG.  7    is an exploded front perspective view of a solenoid assembly according to one embodiment; 
         FIG.  8    is an assembled front perspective view of the solenoid assembly of  FIG.  7   ; 
         FIG.  9    is a side perspective view of the reset plunger assembly and carriage of the solenoid assembly according to one embodiment; 
         FIG.  10    is another side perspective view from a different angle of the reset plunger assembly and carriage similar to  FIG.  9   ; 
         FIG.  11    is a side perspective view of the reset plunger assembly and latching mechanism according to one embodiment; 
         FIG.  12 A  shows a two-piece latching mechanism design according to one embodiment of the present application; 
         FIGS.  12 B- 12 C  show a one-piece latching mechanism design according to one embodiments of the present application; 
         FIG.  13    is a bottom perspective view of the solenoid assembly of  FIG.  7   ; 
         FIG.  14 A  is a side perspective view of the solenoid assembly in a resting position; 
         FIG.  14 B  is a side perspective view of the reset plunger assembly and latching mechanism of the solenoid assembly shown in  FIG.  14 A ; 
         FIGS.  15  -  18    are side perspective views of the reset plunger assembly and latching mechanism in progressive states during the resetting process; and 
         FIG.  19    is a cross-sectional view of the solenoid assembly in a reset position. 
         FIG.  20    is a perspective view of a printed circuit board and coils of a receptacle according to some embodiments. 
         FIG.  21    is a perspective view of the printed circuit board and coils of  FIG.  20    coupled to a manifold of a receptacle according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The application is capable of other embodiments and of being practiced or carried out in various ways. 
     As described herein, terms such as “front,” “rear,” “side,” “top,” “bottom,” “above,” “below,” “upwardly,” and “downwardly” are intended to facilitate the description of the electrical receptacle of the application, and are not intended to limit the structure of the application to any particular position or orientation. 
     Exemplary embodiments of devices consistent with the present application include one or more of the novel mechanical and/or electrical features described in detail below. Such features may include a compactly positioned sensing core, a vertical solenoid, and a latching mechanism including a lifting shelf, a slide mechanism, an intermediate collar, and a cam surface. In some exemplary embodiments of the present application, multiple features listed above are incorporated into one element whereas in other exemplary embodiments, each feature is distinct from one another and coupled to interact with each other. The novel mechanical and/or electrical features detailed herein efficiently utilize the space within the device housing to provide more area for additional features and/or components. 
       FIG.  1    illustrates a perspective view of a GFCI receptacle  10  according to one embodiment of the application. The GFCI receptacle  10  includes a front cover  12  having an outlet face  14  with phase  16 , neutral  18 , and ground  20  openings. The outlet face  14  also has a central opening  22  for a reset button  24  adjacent to an opening  26  for a test button  28 . Rear cover  36  is secured to front cover  12  by screws (not shown or enumerated). Screw terminals  38  mechanically and/or electrically couple wires when wiring the receptacle  10 . A ground yoke/bridge assembly  40  includes standard mounting ears  42  that protrude from the ends of the receptacle  10 . 
     Referring to  FIG.  2   , the GFCI receptacle  10  with the front cover  12 , rear cover  36 , and tamper-resistant mechanisms (not enumerated) removed shows phase terminal  30 , neutral terminal  32 , ground terminal  34 , and a circuit board  58 . The phase, neutral, and ground terminals  30 ,  32 ,  34  are respectively configured to receive electrical plugs  35  of a connecting electrical device, such as a power cord. The circuit board  58  provides control and physical support for most of the working components of the receptacle  10 . The phase and neutral terminals  30 ,  32  may be movable, supported and energized through bus bars  44 ,  46 , respectively. Bus bars  44 ,  46  act as cantilevered arms that support a set of contacts  48 . As shown in the embodiment of  FIG.  3   , the set of contacts  48  include a set of movable contacts  48 A and a set of fixed contacts  48 B. Bus bars  44 ,  46  respectively serve as cantilevered support for the set of movable contacts  48 A while the set of fixed contacts  48 B is supported by a carrier assembly  8 . This configuration may be reversed or changed in other embodiments of the application not described in detail herein. In various embodiments, an indicator light L may be included in the GFCI receptacle  10  and configured to indicate the state of the GFCI receptacle  10 . 
     The resiliency of the cantilevered support provided by the bus bars  44 ,  46  bias the set of movable contacts  48 A away from the set of fixed contacts  48 B. A latching mechanism including a movable carriage, described in further detail in the following figures, is used to engage with the set of movable contacts  48 A, thereby pushing the set of movable contacts  48 A in an upward direction to engage the set of fixed contacts  48 B in a closed position during resetting of the GFCI receptacle  10 . This upward movement of the set of movable contacts  48 A also causes corresponding upward movement in the attached phase and neutral terminals  30 ,  32  closer to the front cover  12  of the receptacle  10 . Electricity may then be delivered from an external power source to the receptacle openings  16 ,  18 ,  20 . In other embodiments, the resiliency of the cantilevered bus bars  44 ,  46  may bias the set of movable contacts  48 A toward the set of fixed contacts  48 B, and a latching mechanism may be employed in reverse to engage and hold the set of movable contacts  48 A away from the set of fixed contacts  48 B in an open position during tripping of the GFCI receptacle  10 . The phase and neutral terminals  30 ,  32  will likewise increase in distance from the front cover  12 , thereby prohibiting the flow of electricity between the external power source and the receptacle openings  16 ,  18 ,  20 . Various embodiments of the latching mechanism may be used by various application designs, the details of each are not disclosed in detail herein. 
     Referring to  FIG.  4 A , in addition to providing structural support for the set of fixed contacts  48 B, the carrier assembly  8  also provides structural support for a sense transformer core  50  and conductor windings  52 ,  54 . In another embodiment shown in  FIG.  4 B , the carrier assembly  8  may provide structural support for multiple sets of sense transformer cores  50 ,  51 , as described in further detail below. Various placements of sense transformer core(s)  50 ,  51  may be possible and will be further described in the following figures. 
       FIG.  5 A  illustrates a perspective view of a core assembly  2  of the GFCI receptacle  10  depicted in  FIG.  1   . A solenoid  60  is oriented to define a central axis A. Multiple sense transformer cores  50  may be stacked together and configured to receive a phase conductor winding  52  and a neutral conductor winding  54  through a common central cavity  56 . Additional sets of stacked sense transformer cores  51  may be added to the carrier assembly  8  (see  FIG.  4 B ) to provide further measurements, such as arc fault measurements, to the GFCI receptacle  10 . The phase and neutral conductor windings  52 ,  54  respectively direct AC current from the phase and neutral terminals  30 ,  32  through the central cavity  56 , where the current may be measured for potential ground faults or arc faults. The AC current flow through the central cavity  56  defines a direction B, which is perpendicular to the central axis A of the solenoid  60 . In the embodiment of  FIG.  5 A , the two sets of sense transformer cores  50 ,  51  are placed symmetrically at two ends of the circuit board  58  with current flow directions parallel to each other. This symmetrical placement allows less or essentially no interference of the sense transformer cores  50 ,  51  with the phase, neutral, or ground openings  16 ,  18 ,  20 , respectively. It would be appreciated by those skilled in the art that other positioning configurations of the sets of sense transformer cores may be possible and not exhaustively described herein. For example, the current flow directions defined by multiple sets of sense transformer cores  50 ,  51  may be at an angle to each other and both parallel to the circuit board  58 . The angle defined by the current flow directions may be acute, right, or obtuse. In another example shown in  FIGS.  5 B-C , only one sense transformer core  50  may be included in the GFCI receptacle  10 . The sense transformer core  50  may be placed at either ends of the circuit board  58  and with various orientations to allow less or essentially no interference with the phase, neutral, and ground openings  16 ,  18 ,  20 . 
     Referring to  FIGS.  6 A-B , the solenoid  60  is coupled to a carriage  62  that is axially movable along the solenoid  60 . On one side, the carriage  62  is coupled to a set of carriage springs  64 , the compression force of which distances the carriage  62  from the circuit board  58  in a rest position. On the other side, the carriage  62  is configured to engage the set of movable contacts  48 A, which presses down on the carriage  62  when in an unbiased resting position. During the resetting process of the GFCI receptacle  10 , the carriage  62  will oppose the resiliency of the abutting set of movable contacts  48 A to advance the set movable contacts  48 A in an upward direction and form electrical communication with the set of fixed contacts  48 B. The upward movement of the set of movable contacts  48 A stops once electrical communication is formed with the set of fixed contacts  48 B. During the tripping process of the GFCI receptacle  10 , the resiliency of the abutting set of movable contacts  48 A pushes the carriage  62  in a downward direction back to its original rest position, thereby effectively breaking the electrical connection between the set of movable contacts  48 A and the set of fixed contacts  48 B. The downward movement range of the set of movable contacts  48 A is limited by a stopping plane in the solenoid support structure  61 . Once the set of movable contacts  48 A hits the stopping plane or returns to the unbiased resting position, push force is no longer exerted on the carriage  62 , thereby effectively halting the downward movement and limiting the maximum range of movement of the carriage  62 . Resetting and latching of the GFCI receptacle  10  may be controlled by the circuit board  58  that receives ground fault and arc fault signal inputs from the sense transformer cores  50 ,  51 . 
       FIG.  7    shows an exploded view of a solenoid assembly  4  of the GFCI receptacle  10  according to one embodiment of the present application. The solenoid assembly  4  includes a reset button  24 , a reset spring  68 , a solenoid  60 , a reset plunger assembly  6 , a solenoid support structure  61 , and a circuit board  58 . In some embodiments, the solenoid support structure  61  is coupled to the circuit board  58  and supports the solenoid  60 . When assembled as shown in  FIG.  8   , the reset button  24  is biased away from the solenoid  60  via the reset spring  68  as long as no push force is exerted on the reset button  24 . When a push force is exerted and subsequently released on the reset button  24 , the compression force of the reset spring  68  returns the reset plunger  66  and the reset button  24  to an original resting position biased away from the solenoid support structure  61 . Likewise, without an externally exerted downward force, the carriage  62  is biased away from the circuit board  58  via the set of carriage springs  64 . The compression force of the carriage springs  64  returns the carriage  62  to an original position biased away from the circuit board  58  when external forces are removed. 
     Referring to  FIGS.  9  -  11   , the reset plunger assembly  6  includes a reset plunger  66  with an intermediate collar  78  and an armature  70  that is axially movable along the length of the reset plunger  66 . The armature  70  contains a slanted projection feature  71  that is energized by the solenoid  60  through which the armature  70  extends. The slanted projection feature  71  is configured to engage with the latching mechanism, which is structurally supported by the carriage  62  and the set of carriage springs  64 . The latching mechanism includes a cam surface  72  coupled to a lifting plate  74 . The lifting plate  74  is coupled through a slot  75  in the carriage  62 , as shown in  FIG.  10   . The lifting plate  74  includes a latching portion  80  configured to receive and engage the intermediate collar  78  of the reset plunger  66  during resetting and tripping of the GFCI receptacle  10 , as shown in  FIG.  11   . A return spring  76  is coupled to one end of the lifting plate  74  and is configured to apply a compression force against one side of the carriage  62 . 
     Two exemplary embodiments of the latching mechanism are shown in  FIGS.  12 A-C . In the two-piece latching mechanism design of  FIG.  12 A , the cam surface  72 A is configured as a separate triangular plate coupled to channels (not enumerated) in the lifting plate  74 A. Additionally, a set of tabs  73 A at one end of the lifting plate  74 A is configured to engage with edges of the cam surface  72 A to transfer a translational force from the cam surface  72 A to the lifting plate  74 A. The return spring  76 A is positioned between the other end of the lifting plate  74 A and one side of the carriage  62 A. The latching portion  80 A is configured as the only opening in the lifting plate  74 A and receives/engages with the intermediate collar  78 . 
     In the one-piece latching mechanism of  FIGS.  12 B-C , the cam surface  72 B is integrated into the lifting plate  74 B as one element. Since the cam surface  72 B does not move independent of the lifting plate  74 B, coupling mechanism including channels (not enumerated) and tabs  74 A are not necessary in the lifting plate  74 B. The lifting plate  74 B includes an opening  77 B and a latching portion  80 B. The return spring  76 B is situated in the opening  77 B and exerts a compression force between edges of the opening  77 B and one side of the carriage  62 B. The latching portion  80 B is configured to receive/engage with the intermediate collar  78 . It would be appreciated by those skilled in the art that other design possibilities not detailed herein may serve to achieve essentially the same results and do not deviate from the teachings of the present application. 
     According to one embodiment shown in  FIG.  13   , a contact spring  82  is coupled to the bottom of the lifting plate  74 . When in an unlatched pushing state as described in further detail below, the contact spring  82  will form electrical communication with at least one contact pads (not shown or enumerated) on the circuit board  58 . This electrical communication will provide a communication signal and power from the circuit board  58  to the solenoid  60 , thereby energizing the armature  70  and resetting the GFCI receptacle  10 . 
     The GFCI receptacle  10  according to embodiments of the present application has four different states: 1) unlatched state or tripped state, 2) unlatched pushing state, 3) latched pulling state, and 4) latched state or reset state. During the tripped state of  FIGS.  14 A-B , the carriage  62  is in a resting position biased away from the circuit board  58  via carriage springs  64 , so the contact spring  82  (not shown) does not form electrical communication with at least one contact pads (not shown or enumerated) on the circuit board  58 . The set of movable contacts  48 A does not engage with the set of fixed contacts  48 B (not shown), and the receptacle terminals  30 ,  32 ,  34  remain biased away from the receptacle openings  16 ,  18 ,  20  via cantilevered bus lines  44 ,  46 . Therefore, the solenoid  60  does not receive external power and is not energized, causing the slanted projection feature  71  of the armature  70  to bias away from cam surface  72  ( FIG.  14 B ). There is no compression force in the return spring  76 , and the engaging portion  80  of the lifting plate  74  is not aligned to receive the intermediate collar  78  biased away from the lifting plate  74 . 
     Once a downward pushing force is received on the reset plunger  66  from a user pushing down on the reset button  24 , the GFCI receptacle  10  enters the unlatched pushing state of  FIG.  15   . In the unlatched pushing state, the downward force pushes the reset plunger  66  towards the lifting plate  74  until the intermediate collar  78  engages with an upper surface of the engaging portion  80 . Because the engaging portion  80  is misaligned with the intermediate collar  78  from the previous tripped state, the intermediate collar  78  engages with but does not latch to the upper surface of engaging portion  80 . Thus, the downward force from the intermediate collar  78  transfers to the engaging portion  80  and the lifting plate  74 , which results in downward movement of the carriage  62  via the slot  75  ( FIG.  10   ). This downward movement continues until the contact springs  82  (not shown) form electrical communication with at least one contact pads (not shown or enumerated) on the circuit board  58 . Upon contact, electrical power and communication is sent from the circuit board  58  to the solenoid  60 , energizing the solenoid on a positive half cycle of the input AC power and moving the armature  70  axially along the reset plunger  66 . Referring to  FIG.  16   , the slanted projection feature  71  of the armature  70  engages with the cam surface  72 , which translates the downward force to a translational force parallel to the circuit board  58 . Translational movement of the cam surface  72  also translationally moves the coupled lifting plate  74  against the compression force of the return spring  76 , thus aligning the engaging portion  80  with the intermediate collar  78 . Referring to  FIG.  17   , the continued downward force on the reset plunger  66  applied by the user causes the intermediate collar  78  to travel through the aligned engaging portion  80 . At this point, the solenoid  60  de-energizes on a negative half cycle of the input AC power and retracts axially along the reset plunger  66 , as shown in  FIG.  18   . The compression force of the return spring  76  pushes the side of the carriage  62  and returns the lifting plate  74  and cam surface  72  back to the original position. In this original position, the intermediate collar  78  is once again misaligned with the engaging portion  80 . When the user releases the downward pushing force on the reset plunger  66 , the reset spring  68  provides an upward pulling force on the reset plunger  66  and intermediate collar  78 , thereby latching and locking the intermediate collar  78  to a lower surface of the engaging portion  80 . Hence, the GFCI receptacle  10  enters the latched pulling state of the resetting process. 
     When the GFCI receptacle  10  is in the latched pulling state shown in  FIG.  19   , the compression force of the reset spring  68  creates an upward force on the reset button  24  and the coupled reset plunger  66 . This upward force pulls the intermediate collar  78  along with the latched lifting plate  74 , which is coupled to the carriage  62  via the slot  75 , causing the carriage  62  to move axially upward along the solenoid  60 . The axially upward movement of the carriage  62  opposes the resiliency of the abutting set of movable contacts  48 A and disconnects the contact springs  82   (not shown) from the at least one contact pads (not shown or enumerated) on the circuit board  58 , thus preventing continued energizations of the solenoid  60 . The carriage  62  engages with the set of movable contacts  48 A to form electrical connection with the set of fixed contacts  48 B. Correspondingly, the receptacle terminals  30 ,  32 ,  34  also resist the cantilevered bus lines  44 ,  46  and move closer to the front cover  12 . Once electrical communication between the set of movable contacts  48 A and the set of fixed contacts  48 B is formed, electricity may be delivered from the receptacle terminals  30 ,  32 ,  34  to the receptacle openings  16 ,  18 ,  20  via the bus lines  44 ,  46 . Hence, the GFCI receptacle  10  is fully reset. 
     When the sense transformer cores  50 ,  51  detect the present of a fault, the GFCI receptacle  10  completes a tripping process. During the tripping process, the GFCI receptacle  10  experiences the states of the resetting process in reverse order, thereby unlatching the intermediate collar  78  from the latching portion  80  and breaking the electrical communication between the set of movable contacts  48 A and the set of fixed contacts  48 B. 
       FIGS.  20  &amp;  21    illustrate a GFCI receptacle  10  according to some embodiments. In the illustrated embodiment, the GFCI receptacle  10  includes a printed circuit board  90 . In some embodiments, the printed circuit board  90  includes one or more slots, or apertures,  92 . As illustrated, the slots  92  may be configured receive, or be placed over, line conductors  94  and/or the neutral conductors  96 , or a portion thereof (for example, bus bars  44 ,  46 ). The printed circuit board  90  may further include, or be coupled to, coils (for example, transformer cores  50 ,  51 ), which may be used to sense and/or monitor a current. In such an embodiment, the coils may also include a slot, aperture, configured to receive, or be placed over, the line conductors and/or the neutral conductors, or a portion thereof (for example, bus bars  44 ,  46 ). 
     In certain other embodiments, additional elements, such as springs, contacts, etc., may be included in various places within the GFCI receptacle  10  to accomplish resetting or tripping of the device. All combinations of embodiments and variations of design are not exhaustively described in detail herein. Said combinations and variations are understood by those skilled in the art as not deviating from the teachings of the present application.