Patent Publication Number: US-6671145-B2

Title: Reset lockout mechanism and independent trip mechanism for center latch circuit interrupting device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in part of application Ser. No. 09/812,288 To Be Determined, filed Mar. 20, 2001, entitled Circuit Interrupting Device with Reset Lockout and Reverse Wiring Protection and Method of Manufacture, by inventors Steven Campolo, Nicholas DiSalvo and William R. Ziegler, which is a continuation-in-part of application Ser. No. 09/379,138 filed Aug. 20, 1999, which is a continuation-in-part of application Ser. No. 09/369,759 filed Aug. 6, 1999, which is a continuation-in-part of application Ser. No. 09/138,955, filed Aug. 24, 1998, now U.S. Pat. No. 6,040,967, all of which are incorporated herein in their entirety by reference. 
     This application is related to commonly owned application Ser. No. 09/812,875 To Be Determined, filed Mar. 20, 2001, entitled Reset Lockout for Sliding Latch GFCI, by inventors Frantz Germain, Stephen Stewart, David Herzfeld, Steven Campolo, Nicholas DiSalvo and William R. Ziegler, which is a continuation-in-part of application Ser. No. 09/688,481 filed Oct. 16, 2000, all of which are incorporated herein in their entirety by reference. 
     This application is related to commonly owned application Ser. No. 09/379,140 filed Aug. 20, 1999, which is a continuation-in-part of application Ser. No. 09/369,759 filed Aug. 6, 1999, which is a continuation-in-part of application Ser. No. 09/138,955, filed Aug. 24, 1998, now U.S. Pat. No. 6,040,967, all of which are incorporated herein in their entirety by reference. 
    
    
     BACKGROUND 
     1. Field 
     The present application is directed to resettable circuit interrupting devices including without limitation ground fault circuit interrupters (GFCI&#39;s), arc fault circuit interrupters (AFCI&#39;s), immersion detection circuit interrupters (IDCI&#39;s), appliance leakage circuit interrupters (ALCI&#39;s), equipment leakage circuit interrupters (ELCI&#39;s), circuit breakers, contactors, latching relays and solenoid mechanisms. More particularly, the present application is directed to circuit interrupting devices that include a circuit interrupting portion that can isolate a power source connector from a load connector. 
     2. Description of the Related Art 
     Many electrical wiring devices have a line side, which is connectable to a source of electrical power, and at least one load side, which is connectable to one or more loads and at least one conductive path between the line and load sides. There are circuit breaking devices or systems such as Ground Fault Circuit Interrupters (GFCIs) which are designed to interrupt power to various loads, such as household appliances, consumer electrical products and branch circuits. GFCI devices, such as the device described in commonly owned U.S. Pat. No. 4,595,894, use an electrically activated trip mechanism to mechanically break an electrical connection between the line side and the load side. Such devices are resettable after they are tripped by, for example, the detection of a ground fault. In the device discussed in the &#39;894 patent, the trip mechanism used to cause the mechanical breaking of the circuit (i.e., the conductive path between the line and load sides) includes a solenoid (or trip coil). A test button is used to test the trip mechanism and circuitry used to sense faults, and a reset button is used to reset the electrical connection between line and load sides. 
     However, instances may arise in which an abnormal occurrence, such as a lightning strike, may disable the trip mechanism used to break the circuit. Accordingly, a user may find a GFCI in a tripped state and not be aware that the internal trip mechanism is not functioning properly. The user may then press the reset button, which will cause the device with an inoperative trip mechanism to be reset. The GFCI will be in a dangerous condition because it will then provide power to a load without ground fault protection. 
     Further, an open neutral condition or reverse wiring condition may be present. Such conditions may be dangerous and it may be advantageous for a GFCI to disable a reset function if such conditions or other conditions exist. 
     The applications referenced above as related applications are commonly owned and incorporated herein by reference. The applications generally relate to locking out a reset function or otherwise disabling a circuit interrupting device on the occurrence of a condition. 
     U.S. Pat. No. 5,933,063 to Keung, et al., purports to describe a GFCI device and apparently utilizes a single center latch. U.S. Pat. No. 5,933,063 is hereby in its entirety be reference. U.S. Pat. No. 5,594,398 to Marcou, et al., purports to describe a GFCI device and apparently utilizes a center latch. U.S. Pat. No. 5,594,398 is hereby in its entirety be reference. U.S. Pat. No. 5,510,760 to Marcou, et al., purports to describe a GFCI device and apparently utilizes a center latch. U.S. Pat. No. 5,594,398 is hereby in its entirety be reference. A typical GFCI design that may benefit from a modification according to the present invention has been marketed under the designation Pass &amp; Seymour Catalog No. 1591. 
     Another GFCI design that may benefit from a modification according to the present invention has been marketed under the designation Bryant Catalog Number GFR52FTW. 
     SUMMARY 
     The present application relates to a resettable circuit interrupting devices that lockout the reset function under certain conditions. In one embodiment, a test mechanism is utilized to test the circuit interrupter before allowing a reset. In an embodiment, a reset plunger is modified to exert force on a trip latch in order to close a test circuit that will allow the reset plunger to continue to a reset position only if the circuit interrupter is functioning. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present application are described herein with reference to the drawings in which similar elements are given similar reference characters, wherein: 
     FIGS. 1 a-b  is an exploded view of a prior art GFCI; 
     FIGS. 2 a-b  is a sectional side view of the mechanism of the prior art GFCI of FIGS. 1 a-b;    
     FIG. 3 is a detailed side view of the mechanism of the prior art GFCI shown in FIGS. 2 a-b  showing the movable contact; 
     FIG. 4 is a side view of a mechanism of a GFCI according to the present invention; 
     FIG. 5 is a side view of a GFCI plunger according to the present invention; 
     FIGS. 6 a-c  is a side view of the GFCI mechanism during stages of reset according to the present invention; 
     FIGS. 7 a-b  is a sectional side view of the mechanism of a prior art GFCI; 
     FIG. 8 is a perspective view of one embodiment of a ground fault circuit interrupting device according to the present invention; 
     FIG. 9 is an exploded view of a portion of a GFCI according to the present invention; 
     FIGS. 10 a-f  is a sectional side view of the mechanism of a portion of the GFCI of FIG. 8; 
     FIG. 11 is an exploded view of a prior art GFCI as shown in FIGS. 7 a-b;    
     FIG. 12 is a perspective view of one embodiment of a ground fault circuit interrupting device according to the present invention; 
     FIG. 13 a  is a perspective view of a solenoid plunger of a GFCI according to another embodiment of the present invention according to FIG. 12 as modified from plunger  166  of FIG. 11; 
     FIG. 13 b  is a perspective view of a reset button/lift plunger/test contact of a GFCI according to the embodiment of the present invention according to FIG. 12 as modified from  128  of FIG. 11; 
     FIG. 13 c  is a perspective view of a trip button of a GFCI according to the embodiment of the present invention according to FIG. 12 as modified from  126  of FIG. 11; 
     FIG. 13 d  is a perspective view of a release lever wire of a GFCI according to the embodiment of the present invention according to FIG. 12; 
     FIG. 13 e  is a perspective view of a contact carrier with switch attached of a GFCI according to the embodiment of the present invention according to FIG. 12 as modified from  180 - 182  of FIG. 11; 
     FIG. 13 f  is a perspective view of a shuttle/test contact of a GFCI according to the embodiment of the present invention according to FIG. 12 as modified from  178  of FIG. 11; 
     FIG. 13 g  is a side and partial top view of the latch of a GFCI according to another embodiment of the present invention that is similar to FIG. 12 as modified from  178  of FIG. 11; 
     FIGS. 14 a-c  is a cutaway representation of part of a prior art GFCI. 
     FIG. 15 is a cutaway representation of part of a GFCI according to an embodiment of the present invention and relates to FIGS. 14 a-c ; and 
     FIGS. 16 a-b  is a cutaway representation of part of a GFCI according to an embodiment of the present invention and relates to FIGS. 14 a-c.    
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The present application contemplates various types of circuit interrupting devices that are capable of breaking at least one conductive path. The conductive path is typically divided between a line side that connects to supplied electrical power and a load side that connects to one or more loads. As noted, the various devices in the family of resettable circuit interrupting devices include: ground fault circuit interrupters (GFCI&#39;s), arc fault circuit interrupters (AFCI&#39;s), immersion detection circuit interrupters (IDCI&#39;s), appliance leakage circuit interrupters (ALCI&#39;s) and equipment leakage circuit interrupters (ELCI&#39;s). 
     For the purpose of the present application, the structure or mechanisms used in the circuit interrupting devices, shown in the drawings and described hereinbelow, are incorporated into a GFCI receptacle suitable for installation in a single-gang junction box used in, for example, a residential electrical wiring system. However, the mechanisms according to the present application can be included in any of the various devices in the family of resettable circuit interrupting devices. 
     The circuit interrupting and reset portions described herein preferably use electro-mechanical components to break (open) and make (close) one or more conductive paths between the line and load sides of the device. However, electrical components, such as solid state switches and supporting circuitry, may be used to open and close the conductive paths. 
     Generally, the circuit interrupting portion is used to automatically break electrical continuity in one or more conductive paths (i.e., open the conductive path) between the line and load sides upon the detection of a fault, which in the embodiments described is a ground fault. The reset portion is used to close the open conductive paths. 
     In the embodiments including a reset lockout, the reset portion is used to disable the reset lockout, in addition to closing the open conductive paths. In this configuration, the operation of the reset and reset lockout portions is in conjunction with the operation of the circuit interrupting portion, so that electrical continuity in open conductive paths cannot be reset if a predetermined condition exists such as the circuit interrupting portion being non-operational, an open neutral condition existing and/or the device being reverse wired. 
     In the embodiments including an independent trip portion, electrical continuity in one or more conductive paths can be broken independently of the operation of the circuit interrupting portion. Thus, in the event the circuit interrupting portion is not operating properly, the device can still be tripped. 
     The above-described features can be incorporated in any resettable circuit interrupting device, but for simplicity the descriptions herein are directed to GFCI receptacles. 
     A circuit interrupting device having any one or more of a reset lockout mechanism, an independent trip mechanism or a separate user load break point may be desirable. 
     A portion of the mechanism of a prior art GFCI is shown in FIGS. 1 a ,  1   b ,  2   a ,  2   b  and  3 . 
     The relevant portion of the operation of the prior art GFCI is summarized as follows. When the reset button  80  is pressed down the plunger cone forces the latch  60  to be pressed to the right in FIG. 2 a . The latch  60  will come into a position where the hole in the latch  60  is aligned with the plunger  78  such that the conical tip  78   b  of the plunger  78   a  will pass through the hole. When the plunger goes all the way through the hole, the sliding latch is biased to go back to the left in FIG. 2 b , such that the shoulder of the plunger conical tip comes into contact with the latch  60 . When the reset button is released, the plunger  78  is biased upward and the latch  60  is pressed upward causing the device to reset and cause contact  30  to connect to contact  70  in FIG.  3 . If the device trips and the solenoid  50  causes the plunger  54  to move latch  60  to the right, the plunger  78  will pass upward through latch  60  and allow the latch, which is biased down to break the contacts. 
     With reference to FIGS. 4-6, an embodiment of the present invention includes a reset plunger  78 ′ that includes a notched conical tip  78   b′  that forces latch  60 ′ to act to close switch S 1  when the reset plunger  78 ′ is depressed. When switch S 1  is depressed, a circuit is closed from the load phase to the line neutral through a current limiting resistor R. 
     With reference to FIG. 5, the embodiment of the present invention includes a reset plunger  78 ′ that includes a notched conical tip  78   b′.    
     With reference to FIGS. 6 a - 6   c , the reset lockout mechanism of the this embodiment is described. When the reset plunger  78 ′ starts down in direction A, the latch  60 ′ is in its leftmost position. The notched plunger tip  78   b′  will hit the top of latch  60 ′ and force it down such that switch S 1  is closed to engage a test. As shown in FIG. 6 b , in this embodiment, the test is accomplished by completing the circuit from the load phase to the line neutral through a current limiting resistor R. If the circuit interrupting device is operational and properly wired as shown by the test, the solenoid forces plunger  54  to slide latch  60 ′ in direction B out from under the notch in  78   b′  allowing the reset plunger  78 ′ to complete its journey in direction A such that latch  60 ′ will move left and rest atop plunger shoulder  78   c′  as shown in FIG. 6 c . Thereafter, the reset plunger, when released will pull up latch  60 ′ under its bias to complete the reset of the device. 
     As can be appreciated, if the test fails, the latch  60 ′ will not move in direction B and the notched conical tip  78   b′  of the reset plunger  78 ′ will keep the plunger from going through the hole in the latch  60 ′ and the device will be locked out from the reset function. 
     As can be appreciated, a bridge circuit may be implemented to provide reverse wiring protection as described in the pending commonly owned application referenced above. For example, with reference to FIG. 1 a  of the prior art, a single contact  68 , 70  is utilized to close a circuit to a load phase terminal  64   c  and two user load phase terminals  64   a  and  64   b  through connector  64 . As can be appreciated, terminal  64   c  could be isolated from connector  64  and arm  24  may utilize a second contact to independently provide a circuit to  64   c . Similarly, the modification would be made to both conductive paths of the device. Furthermore an indicator such as a neon bulb may be utilized to indicate a reverse wiring condition. 
     As can also be appreciated, the device may be manufactured or initialized into a tripped state and distributed in the tripped state such that a user would be required to reset the device before using it. 
     A portion of the mechanism of another prior art GFCI is shown in FIGS. 7 a , and  7   b  and is somewhat similar to the previously described prior art unit in some details. 
     The relevant portion of the operation of the prior art GFCI is summarized as follows. When the reset button  128  is pressed down the lower cone shaped end of the plunger forces a sliding spring latch to the side until the plunger can go through and the latch will spring back to rest on the shoulder of the sliding spring latch and then pull the device into a reset position. 
     With reference to FIGS. 8-10 f , another embodiment of the present invention includes a GFCI  201  having a rest button  210  and trip button  212 . 
     With reference to FIG. 9, the reset button  210  has a bias spring  210   a , a shaft  210   b , a conical tip with step  210   d  and the conical tip has a shoulder  210   c . The trip button  212  has a bias spring  212   a , and a formed wire shaft  212   b . A sliding plate  214  and sliding spring  216  fit into grooves of housing  220  that is mated to solenoid  218  and solenoid plunger  218   a . Switch  222  is mounted in the housing under the sliding spring  216 . 
     With reference to FIGS. 10 a-f , the operation of the relevant portion of the device is described. FIG. 10 a  shows the device as in normal operation with current allowed to pass through. 
     FIG. 10 b  shows the operation when tripped. Solenoid  218  pulls plunger  218   a  and pushes sliding spring  216  and sliding plate  214  to the right such that sliding spring  216  no longer holds down reset plunger shoulder  210   c  and the spring bias of spring  210   a  forces plunger  210   b  upward and the circuit is broken (not shown). 
     FIG. 10 c  shows the reset lockout mechanism in use. After the tripped state, when the reset button  210  is depressed, the step in conical tip  210   d  presses down on sliding spring  216  and forces switch  222  to close. This view is prior to the solenoid actuation. 
     FIG. 10 d  shows the test being completed successfully. The switch  222  closes the test circuit that causes solenoid  218  to fire and the plunger forces sliding spring  216  and sliding plate  214  to the right, allowing the plunger to continue to travel downward once the plunger tip step  218   d  clears the hole in the sliding spring  216   b.    
     FIG. 10 e  shows the device after the test is completed. The plunger tip  210   d  clears the hole  216   b  and the sliding spring releases upward and test switch  222  opens ending the test cycle. The solenoid  218  releases plunger  218 ′ and sliding spring  216  and sliding plate  214  return to the left. The sliding spring  216  then rests on top of the plunger tip shoulder  210   d  and the spring  210   a  pulls the spring up to reset the device. 
     FIG. 10 f  shows the independent trip mechanism of the device  201 . The independent trip will trip the device without using the sense mechanism or the solenoid. It is preferably a mechanical device, but can be implemented with electronic or electro-mechanical components. As trip button  212  is pressed downward, formed wire  212   b  moves downward and the sloped shape interacts with hole  214   a  of sliding plate  214  to force the sliding plate and sliding spring to the right such that hole  216   b  moves enough to allow reset plunger  210   b  to release upward and trip the device. Accordingly, the sliding plate  214  is utilized to move the sliding spring  216  into alignment. The sliding plate  214  may be held in place by the middle and bobbin housings. The formed wire  212   b  causes a cam action and moves the sliding plate  214 , causing the device to trip. 
     As can be appreciated, the mechanical trip described will function to trip the device even if the solenoid or other parts are not functioning. 
     As can be appreciated from the discussion above, a bridge circuit may be implemented to provide reverse wiring protection as described in the pending commonly owned application referenced above. Furthermore an indicator such as a neon bulb may be utilized to indicate a reverse wiring condition. As can also be appreciated, the device may be manufactured or initialized into a tripped state and distributed in the tripped state such that a user would be required to reset the device before using it. 
     FIG. 11 shows a representative prior art GFCI without a reset lockout mechanism or independent trip. 
     FIGS. 12 and 13 a - 13   f  show modifications to parts of the representative GFCI to facilitate a reset lockout and independent mechanical trip according to another embodiment of the invention. 
     The primary purpose of the Reset Lockout and Mechanical Trip is to lockout the resetting of a GFCI Type device unless the device is functional, as demonstrated by the built in test, at the time of reset. The Mechanical Trip is a part of this test cycle by insuring that the device is in the tripped state even if the device is unpowered or non-operational. The means and electronics by which this device trips upon ground fault conditions are not modified. These same means and electronics are now employed as a condition of reset. The test function is incorporated in the reset function, therefore no separate test is required and the test button is employed for a mechanical reset. 
     As shown in FIGS. 13 a-f , the reset plunger  328  was changed from a semi cone (to lead into the shuttle), to a reverse taper. The diameter of the top edge (the area that latches the contacts closed) remains unchanged so that the holding power and release effort remains unchanged from the original design. The lower end has the taper removed and the diameter increased so that it will not pass through the shuttle unless the shuttle is positioned in the release position by the activation of the solenoid. The shaft notch  328   a  is insulated and the bottom  328   b  is conductive. 
     Additionally, the contact carrier  380  has a contact added  382  so that when the plunger is in the tripped position, the plunger is connected to the phase line, after the point at which it passes through the sense transformer. Additionally, the shuttle  378  is wired to the circuit board at the point of the original test contact. 
     In a further embodiment, another test switch may be used. Pushing the Test button  326  mechanically trips the plunger by moving the shuttle in the same direction as would the solenoid. This is independent of power or functionality of the unit. 
     While the large end of the plunger is within the contact carrier, it is connected to the phase line. When the reset button is pressed, the plunger pushes against the shuttle, but does not pass through. The shuttle is the other terminal of the test contact and contacting it with the live plunger initiates the test cycle. If the test is successful, the firing of the solenoid (exactly the same as on the trip cycle) opens the port for the plunger to pass through to the armed position. This causes the large end of the plunger to pass completely through the contact carrier, removing the phase line contact from the plunger, ending the test cycle. Upon release of the reset button, the return spring lifts the shuttle, raising the contact carrier to establish output exactly as before the modification. 
     In order for the above design to function a momentary operation of the latch solenoid must operate. If this operation is activated via the test circuit their reset of the device also tests the device eliminating the need for the test button to perform an electrical trip. This leaves the test button available to be converted to a mechanical trip mechanism. 
     The reset mechanism could have electrical contacts added such that the base of the plunger (latch) makes contact in the side wall of the guide hole located on the contact carrier of the device. This side wall contact would be connected using a small gauge very flexible conductor to the existing test contact (molded in the solenoid housing or on the PC board). A second connection would be required from the phase load conductor after the point at which it passes through the sense coils to the latch mechanism (the part that is acted on by the solenoid.) 
     The reset button is depressed. The plunger on the lower end of the reset button is in electrical contact with its guide hole which in run is wired to the electrical test circuit. When the bottom end of the plunger contacts the latch (which is in electrical contact with phase line) if the device is powered and if the test circuit is functional, the solenoid moves the latch to the open position and the plunger passes through to the opposite side. As the plunger is no longer in electrical contact with the side wall of the guide, the solenoid releases the latch to return to its test position. Releasing the reset button pulls the latch up as in the original design. 
     A mechanical test mechanism may be fashioned by removing and discarding the test electrical contact clip (switch) of FIG.  11 . 
     As shown in FIG. 13 g , a tab with a hole may be added to the part of the latch that is operated by the solenoid in the area of the spring end  378   a . Corresponding holes and mechanism may be added to the test button such that depressing the test button pushes a lever into the hole in the latch that would cause it to move in a manner similar to activation of the solenoid, causing the latch plunger to release on in a normal trip mode. 
     The latch (shuttle) is modified to have the “plunger operating hole” size reduced to prevent the plunger from being forced through when the latch is not in the release position. 
     Another embodiment is described with reference to FIGS. 14-16. FIGS. 14 a-c  show a prior art GFCI  400  in various stages of operation as described. 
     Referring to FIG. 14 a , when the reset button  430  is pressed down in direction B, a raised edge  440  on the reset arm  438  slides down to an angled portion  451  of a lifter  450  as shown in FIG. 14 c  (but shown during a trip). As shown in FIGS. 14 b  and  c , the spring  434  on the reset arm  438  allows it to move in direction D as it slides past the notch  451  in the lifter  450 . When the raised edge  440  of the reset arm  438  clears the lifter  450 , the reset arm moves back in direction C to a vertical position under the bias of spring  434 . The shoulder of the raised edge  440  then becomes engaged with the bottom of lifter  450  because the reset arm is under bias upward of reset spring  436 . The device is now reset as shown in FIG. 14 b  with contact  458  engaging  470  and contact  456  engaging contact  472 . The lifter  450  is biased down on spring  452  on the right side of pivot  454  and the reset mechanism is biased upward by spring  436 . Accordingly, as shown in FIG. 14 c , when the solenoid  462  fires because of a trip or test, the reset bar  438  is moved in the D direction by plunger  460  until the raised edge  440  clears the lifter notch  451  and the bias spring  452  forces the circuits open by pushing the lifter  450  down on the right side of pivot  454 . 
     Another embodiment of a GFCI  500  of the present invention is shown with reference to FIGS. 15-16 b , and in relation to FIGS. 14 a-c . As shown in the prior art FIG. 16 a , there is an angled portion of the lifter  451  that is removed as shown in FIG. 16 b  to create lifter edge  551 . Accordingly, as shown in FIG. 15, the solenoid  562  must fire and move the reset arm  538  past the lifter  550  and edge  551 . If the solenoid does not fire, the reset arm will not be able to pass the lifter as in the prior art device because the angled lifter notch  451  is removed. 
     Another arm  582  is attached to the reset button which makes contact with contact  584  when reset button  530  is pressed down in the B direction. The test circuit (not shown) is then completed using current limiting resistor R. this will fire the solenoid  562  and move the reset arm  538  past the lifter  550  allowing the device to reset. If the solenoid  562  fails to fire for some reason, the device will be locked out and a reset not possible. 
     In another embodiment, an independent trip mechanism is provided as a mechanical trip feature based upon the test button  510 . When test button  510  is depressed in the B direction, angled test bar  516  cams angled trip bar  580  in the D direction. This will push the reset bar  538  and release the reset button to trip the device (not shown). As can be appreciated, FIG. 15 shows the device already tripped. Because allowing the manual trip would not be useful, ribs (not shown) are placed to ensure that the test button may only be depressed when the reset button is down and the device is powered. 
     Accordingly, the device  500  may be tripped even if the solenoid  562  is not able to fire. 
     As noted, although the components used during circuit interrupting and device reset operations are electro-mechanical in nature, the present application also contemplates using electrical components, such as solid state switches and supporting circuitry, as well as other types of components capable or making and breaking electrical continuity in the conductive path. 
     While there have been shown and described and pointed out the fundamental features of the invention, it will be understood that various omissions and substitutions and changes of the form and details of the device described and illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention.