Patent Abstract:
A circuit breaker includes a housing forming an opening. A push switch is connected to a test circuit to enable testing of the test circuit in accordance with closing the push switch. A flexible membrane is formed in the opening and configured to form a seal between the housing and the flexible membrane. The flexible membrane is located in an operative relationship with the push switch such that pushing the flexible membrane results in a displacement of the push switch.

Full Description:
RELATED APPLICATION INFORMATION 
     This application claims priority to provisional application Ser. No. 61/029,584 filed on Feb. 19, 2008, incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     This disclosure relates to circuit breakers, and more particularly, to a circuit breaker having a moisture resistant push to test button. 
     2. Description of the Related Art 
     Circuit breakers with ground fault or arc fault systems typically include a self-test button. These button designs usually include a mechanical spring, a secondary contact, and a hard plastic Push to Test (PTT) button. The test button is typically biased by a mechanical force provided by the spring. As the test button is depressed, the mechanical spring makes contact with a secondary contact. The secondary contact can be made of a similar material as the mechanical spring and may have spring type properties, or the secondary contact may be a stationary pin mounted on a printed circuit board (PCB). 
     One disadvantage is that a gap between the test button and a housing of the circuit breaker is present before or during when the button is depressed. When the gap between the button and the housing is present, several concerns arise related to moisture, corrosion, and potential electric shock. With the gap present, internal components are exposed to outside moisture and/or other containments that could disable the tripping functions of the test button. Although PCB&#39;s are typically conformally coated, this does not guarantee that moisture could not damage the PCB and/or related electrical components and disable the push to test button. 
     From a manufacturing standpoint, special care needs to be taken to ensure the contacting surfaces are not subject to corrosion or water damage. Current designs may be subject to corrosion on the contact surfaces if the mechanical parts were not properly coated, thus, disabling the push to test button functions. Further, the possibility of the user being exposed to electrical shock may be present. 
     SUMMARY OF THE INVENTION 
     A circuit breaker includes a housing forming an opening. A push switch is connected to a test circuit to enable testing of the test circuit in accordance with closing the push switch. A flexible membrane is formed in the opening and configured to form a seal between the housing and the flexible membrane. The flexible membrane is located in an operative relationship with the push switch such that pushing the flexible membrane results in a displacement of the push switch. 
     A flexible membrane for covering a button opening in a circuit breaker housing includes a planar section dimensioned and configured to cover an opening in a housing of a circuit breaker. A raised portion is centrally formed on the planar portion. Walls are formed about a perimeter of the planar section and form a groove about the perimeter of the planar section. The walls extend outward from the parallel portion. The walls are configured to clamp on housing walls of the circuit breaker to form a seal to exclude moisture and contaminants from the housing at the opening. 
     These and other objects features and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       This disclosure will present in detail the following description of preferred embodiments with reference to the following figures wherein: 
         FIG. 1  is a perspective view showing a circuit breaker assembly having a flexible membrane push to test button in accordance with one embodiment; 
         FIG. 2  is a magnified perspective view showing the flexible membrane push to test button in accordance with  FIG. 1 ; 
         FIG. 3  is an exploded view showing a housing portion removed in accordance with one embodiment; 
         FIG. 4  is an exploded view showing a housing portion and a partition removed to show internal circuitry for operating and testing the circuit breaker in accordance with one embodiment; 
         FIG. 5  is an exploded perspective view showing an electronic compartment of the breaker and showing a button interface in accordance with the present principles; 
         FIG. 6  is an exploded perspective view showing the electronic compartment and showing the button interface from a different angle than  FIG. 5 ; 
         FIG. 7  is a cross-sectional view showing a front view of the button interface in accordance with the present principles; and 
         FIG. 8  is a cross-sectional view showing a side view of the button interface in accordance with the present principles. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The present principles provide a push to test button that protects internal electrical components from moisture damage and/or other containments that could disable a circuit breaker device. In addition, the present principles provide protection for the user from an electrical shock due to the internal circuitry. The present embodiments reduce the concern for damage or injury due to moisture or other contaminants entering between the push to test button and an electronic housing of the circuit breaker. The present aspects minimize any gaps around the push to test button thus reducing the possibility of moisture or other materials from seeping in the electronic compartment and disabling the circuit breaker device. An improved seal for the button reduces the risk of electrical shock that may be present with a gap. 
     The present invention is not limited to the illustrative example and may be employed with other electrical devices and components. The present embodiments are illustratively described with reference to a push to test button, but may be employed with any button or device that enters through the housing wall of a circuit breaker. All statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). Thus, for example, it will be appreciated by those skilled in the art that the diagrams presented herein represent conceptual views of illustrative system components and/or circuitry embodying the principles of the invention. 
     Referring now in specific detail to the drawings in which like reference numerals identify similar or identical elements throughout the several views, and initially to  FIGS. 1 and 2 , a circuit breaker  10  is illustratively shown having a push to test button  14  in accordance with the present principles.  FIG. 1  shows an entire circuit breaker assembly while  FIG. 2  shows a magnified view of the push to test button  14 . One advantage of the present embodiment is that a superior push to test button  14  is provided where no gap is created around the push to test button  14  before the button  14  is depressed or while the button  14  is being pressed. This functionality provides moisture protection and reduces the potential of electrical shock. 
     Breaker  10  is depicted as a single pole breaker; however, multiple pole breakers (e.g., two pole circuit breakers) may be employed as well that include the push to test button  14  for tripping the device  10 . The circuit breaker  10  may include any design having AFCI and/or GFCI protection and include thermal/magnetic protection and electronic components used to trip the circuit. A handle  16  is provided to switch the breaker  10  on or off or to reset the breaker  10  after a trip. A wire coil  18  is shown and employed for connecting the breaker  10  for operation. 
     Referring to  FIGS. 3 and 4 , exploded views of the breaker housing  10  are illustratively depicted. An electronics housing  24  includes electronic components employed in carrying out the functions of the breaker  10 . For example, housing  24  includes a printed circuit board  28  employed in controlling a solenoid  30 . Solenoid  30  is employed in tripping and resetting mechanical components of the circuit breaker  10 . These mechanical components are provided in housing portion  22 . Housing portions  22  and  24  are separated by a partition  26 , which includes openings to permit interfacing between electronic components in housing  24  and the mechanical components in housing  22 . 
     Different breaker designs may include different pole mechanisms for tripping the breaker. However, many designs include a fixed and moveable contact, where the moveable contact is attached to a moveable arm. The moveable arm is tripped under current surges and overload conditions. For GFCI and AFCI circuits, an electronic protection circuit on PCB  28  is provided that senses ground faults or arcing faults. A circuit (e.g., on the PCB  28 ) may be tested to determine proper operation by pressing the push to test button  14 . Push to test functions are known in the art. 
     Referring to  FIGS. 5 and 6 , perspective views of the push to test button region are illustratively depicted. In  FIG. 5 , housing  24  is opened and shows button  14  includes a push switch  32  with an additional flexible membrane  15 . The flexible membrane  15  may include a flexible material that is water or contaminant resistant. One material for membrane  15  may include rubber or a flexible polymer material. Membrane  15  includes walls  34 , which form a groove  36  about a perimeter of the membrane  15 . The groove  36  is designed to interface with walls  38  of the housing  12  (in this case housing portion  24  and housing portion  26  ( FIG. 3 )). Membrane  15  provides a seal with the surrounding housing material (e.g., plastic). 
     In one embodiment, the flexible membrane  15  extends over and below walls  38  of the housing  12 . The dimensions of the groove  36  are preferably undersized to provide a snug fit with housing walls  38 . The flexible membrane  15  is preferably formed from a dielectric material with a sufficient thickness and/or dielectric constant to prevent electrical shock to a user during operation. Any moisture or liquids in contact with the breaker  10  will not be permitted to enter the breaker  10  through the push to test button  14  as a result of the seal provided by the flexible membrane  15 . With no gap present, users are limited to any exposure to electrical shock. Further, the flexible membrane  15  becomes the push to test button for the device  10 , making the assembly more moisture/humidity/contaminant resistant near the test button area as compared to conventional designs. 
     Referring to  FIGS. 7 and 8 , a front cross-sectional view and a side cross-sectional view of the flexible membrane  15  are respectfully shown. Decimal dimensions are provided in inches for illustrative purposes only. Push switch  32  is biased upward by a spring or the like (not shown). When the flexible membrane  15  is pressed down in the direction of arrow “A”, the push switch  32  is moved downward, and closes a self test circuit formed on PCE  28 . 
     The flexible membrane  15  covers an opening in the circuit breaker housing. The membrane  15  includes a planar section  40  dimensioned and configured to cover the opening in the housing  24  (and  26 ) of the circuit breaker  10 . A raised portion  42  is centrally formed on the planar section  40 . The raised portion may be above the planar section  40 , be below the planar section  40  or both. Walls  34  are formed about a perimeter of the planar section  40  and form a groove  36  about the perimeter of the planar section  40 . The walls  34  extend outward from the planar section  40 . The walls  34  are configured to clamp on housing walls  24  and  26  of the circuit breaker  10  to form a seal to exclude moisture and contaminants from the housing at the opening. The clamp on the housing walls  24  and  26  is preferably caused by an interference fit between the groove  36  and the housing walls  24  and  26 . 
     The self-test is performed on the breaker to determine whether the breaker  10  is capable of ground or arc fault detection. The push to test button may be employed to disable the breaker. A reset button may also be employed to reset the power (turn the power back on) after a test. It should be understood a circuit breaker may have one or more buttons and the that present principles are directed to all of these buttons. For example, the push to test buttons may include a test button and/or a reset button. Other buttons may also be employed and benefit for the present teachings. 
     Having described preferred embodiments for moisture resistant push to test button for circuit breakers (which are intended to be illustrative and not limiting), it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments of the invention disclosed which are within the scope and spirit of the invention as outlined by the appended claims. Having thus described the invention with the details and particularity required by the patent laws, what is claimed and desired protected by Letters Patent is set forth in the appended claims.

Technology Classification (CPC): 7