Abstract:
An electrical switching system comprises a main housing enclosing an actuable apparatus including an actuator extending outwardly of the housing. A contact housing encloses an electrical contact and a pusher selectively actuable by the actuator to operate the contact. A mortise is provided on one of the main housing and contact housing and a tenon is provided on the other of the main housing and contact housing for joining the contact housing to the main housing. A snap lock resiliently locks the contact housing to the main housing.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS  
       [0001]    The present U.S. patent application having at least one common inventor as  
         [0002]    U.S. patent application Ser. No.______ entitled “System and Method for Auxiliary Contact Assembly” (2001P17284 US), and  
         [0003]    U.S. patent application Ser. No.______ entitled “System and Method for Mounting a Pusher and Moveable Contact in a Contact Block” (2001P17288 US), and  
         [0004]    U.S. patent application Ser. No.______ entitled “System and Method for Mounting a Moveable Contact in a Contact Block” (2001P17289 US), and  
         [0005]    U.S. patent application Ser. No.______ entitled “Contact Block Assembly and Method of Assembling a Contact Block Assembly” (2001P17279 US), and  
         [0006]    U.S. patent application Ser. No.______ entitled “Pusher Assembly and Method for Assembling a Pusher Assembly” (2001P17280US),  
         [0007]    U.S. patent application Ser. No.______ entitled “Movable Contact and a Method of Assembling a Pusher Assembly having a Movable Contact”(2001P17281US),  
         [0008]    are filed with the U.S. Patent and Trademark Office concurrently on Sep. 21, 2001, the entirety of each being incorporated herein by reference.  
     
    
     
       TECHNICAL FIELD OF THE INVENTION  
         [0009]    This invention relates to a contact assembly for use in an electrical switching apparatus designed to facilitate mounting thereon and removal therefrom.  
         BACKGROUND OF THE INVENTION  
         [0010]    A conventional electrical switching apparatus in one known form typically comprises an electromagnetically actuable device having a magnetic core proximate an armature. Typically, a coil is electrically energized to draw the armature to the magnetic core. The electromagnetically actuated device may be a control relay, a contactor, a motor starter or the like. The armature is operatively associated with a movable device such as an actuator. With an electrical switching apparatus the actuator operates a contact assembly.  
           [0011]    The contact assembly may be an integral component of the electrical switching apparatus or it may an auxiliary device to be added thereto. In the case of an auxiliary contact assembly, a housing conventionally supports an electrical contact and a pusher. The pusher is selectively actuated to operate the contact. One such conventional auxiliary contact assembly is removably mounted to a side of the electromagnetically actuable device. A mortise and tenon construction joins the auxiliary contact device to the electromagnetically actuable device. A side mounted screw and nut are turned to lock the auxiliary contact assembly on the electromagnetically actuable device. This requires the use of a screwdriver and some care in controlling orientation of the screw and nut during installation and removal. Moreover, the user must have side access to the electromagnetically actuable device which might require removal of the device from a panel.  
           [0012]    Accordingly, there is a need for a contact assembly for use in electrical switching apparatus designed to facilitate mounting thereon and removal therefrom.  
         SUMMARY OF THE INVENTION  
         [0013]    In accordance with the invention there is provided a contact assembly for use in electrical switching apparatus designed to facilitate mounting thereon and removal therefrom.  
           [0014]    Broadly, there is disclosed herein a contact assembly for use in an electrical switching apparatus having an actuator. The contact assembly includes a housing enclosing an electrical contact and a pusher selectively actuable by the actuator to operate the contact. Means are provided for joining the housing to the electrical switching apparatus and means for resiliently locking the housing to the electrical switching apparatus.  
           [0015]    It is a feature of the invention that the joining means comprises a tenon on the housing received in a mortise on the electrical switching apparatus. It is another feature of the invention that the joining means comprises a dove-tail joint joining the housing to the electrical switching apparatus.  
           [0016]    It is another feature of the invention that the locking means comprises a snap lock.  
           [0017]    It is still a further feature of the invention that the locking means comprises a flexible web extending from the housing with a projection on the web engaging a rib on the electrical switching apparatus.  
           [0018]    There is disclosed in accordance with another aspect of the invention an electrical switching system comprising a main housing enclosing an actuable apparatus including an actuator extending outwardly of the housing. A contact housing encloses an electrical contact and a pusher selectively actuable by the actuator to operate the contact. A mortise is provided on one of the main housing and contact housing and a tenon is provided on the other of the main housing and contact housing for joining the contact housing to the main housing. A snap lock resiliently locks the contact housing to the main housing.  
           [0019]    It is a feature of the invention that the main housing comprises first and second parallel ribs having facing channels to define the mortise and a third rib extending angularly from the first and second ribs. The snap lock comprises a flexible web extending from the contact housing with a projection on the web engaging the third rib. The tenons extend from the web in alignment with the projection. A blade extends from the web to guide the snap lock.  
           [0020]    There is disclosed in accordance with still another aspect of the invention an electrical switching system comprising a main housing enclosing an actuable apparatus including an actuator having opposite ends extending outwardly of opposite sides of the main housing. A contact housing encloses an electrical contact and a pusher selectively actuable by the actuator to operate the contact. A mortise on each side of the main housing and a tenon on each side of the contact housing join the contact housing to either side of the main housing with the pusher proximate one of the ends of the actuator. A snap lock resiliently locks the contact housing to the main housing.  
           [0021]    There is disclosed in accordance with yet another aspect of the invention the method of mounting a contact block to an electrical switching apparatus, comprising providing a main housing enclosing an actuable apparatus including an actuator having opposite ends extending outwardly of opposite sides of the main housing and a mortise on each side of the main housing aligned with a rib; providing a contact housing enclosing an electrical contact and a pusher selectively actuable by the actuator to operate the contact and having a tenon and a snap lock element; joining the contact housing to either side of the main housing with the pusher proximate one of the ends of the actuator by sliding the tenon in one of the mortises; and resiliently locking the contact housing to the main housing by engaging the ribs with the snap lock element. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a perspective view illustrating a contact assembly used with an electrical switching apparatus in accordance with the invention;  
         [0023]    [0023]FIG. 2 is an exploded view of the contact assembly of FIG. 1;  
         [0024]    [0024]FIG. 3 is a plan view of the contact assembly of FIG. 2 with a cover removed;  
         [0025]    [0025]FIG. 4 is a perspective view of a housing of the contact assembly of FIG. 2;  
         [0026]    [0026]FIG. 5 is a side elevation view of the housing of FIG. 4;  
         [0027]    [0027]FIG. 6 is a side elevation view of a base of the electrical switching apparatus of FIG. 1; and  
         [0028]    [0028]FIG. 7 is an inside plan view of the base of FIG. 6. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]    Referring to FIG. 1, a contact assembly in the form of an auxiliary contact block  20  for use with an electrical switching apparatus in the form of an electrical contactor  22  is illustrated. The present invention relates to use of a snap mounting for removably mounting the auxiliary contact block  20  to the contactor  22 , as described below.  
         [0030]    The contactor  22  is an electromagnetically actuable device and includes a mounting plate  24  for mounting in a control panel or the like. A main housing  26  is mounted to the mounting plate  24 . The main housing  26  includes a base  28 , a switch housing  30  and a cover  32 . Although not specifically illustrated herein, the main housing  26  encloses an electrical coil associated with a magnetic core and armature for driving an actuator having opposite ends  34 , one of which is shown in FIG. 1. Additionally, the main housing  26  encloses various electrical contacts which can be opened or closed responsive to energization of the coil. The actuator ends  34  extend outwardly of opposite sides of the main housing  26 . As a result, the auxiliary contact block  20  can be mounted to either side of the main housing  26 .  
         [0031]    Referring to FIGS. 2 and 3, the auxiliary contact block  20  includes a housing  40  and a cover  42  to define an interior space  44 . Both the housing  40  and cover  42  ore of one-piece molded plastic. Mounted in the interior space  44  are a pair of stationary normally open contacts  46 , a pair of stationary normally closed contacts  48 , a pair of movable contacts  50 , a pair of contact springs  52 , a pusher  54  and a return spring  56 .  
         [0032]    The housing  40  includes a generally planar outer wall  60  connected to an upwardly turned side wall  61 . The side wall  61  extends generally around the perimeter of the outer wall  60  except for terminal openings  62 . The cover  42  includes a generally planar outer wall  63  connected to a downwardly turned partial side wall  64 . The side wall  64  extends generally around a portion of the perimeter of the outer wall  63  and provides terminal openings  65 . Particularly, the cover outer wall  63  is virtually a mirror image of the housing outer wall  60 . The cover side wall  64  and housing side wall  61  provide a perimeter wall around the interior space  44  with the openings  62  and  64  in the same positions to provide external access to the stationary contacts  46  and  48 . A plurality of collars  66  extend upwardly from the housing outer wall  60 . The collars  66  receive posts (not shown) extending downwardly from the cover outer wall  63  to retain the cover  42  on the housing  40 .  
         [0033]    An annular ring  68  on the housing outer wall  60 , and a similar annular ring (not shown) on the cover outer wall  63 , receive a pivot post  70  of the pusher  54  to pivotally mount the pusher  54  in the interior space  44 . The pusher  54  also includes an arm  72  that extends outwardly of an opening  74  in the housing side wall  61 , as particularly illustrated in FIG. 3. The pusher  54  also includes a post  76  extending outwardly on either side of the pivot post  70 . Each post  76  is adapted to receive one of the contact springs  52  and movable contacts  50 .  
         [0034]    The stationary contacts  46  and  48  are mounted in the housing  40  as illustrated in FIG. 3. With the pusher  54  pivotally mounted in the housing  40 , each of the movably contacts  50  is positioned in proximity to one of the stationary contact pairs  46  or  48 . In the illustrated embodiment of the invention, one of the movable contacts  50  provides a normally open contact arrangement relative to the stationary contacts  46  and a normally closed contact relationship relative to the stationary contacts  48 . Other contact relationships may also be used. The return spring  56  biases the pusher  54  into a normal position. The stationary contacts  46  and  48  and pusher  54  and return spring  56  are loosely held in the interior space  44  captured between the cover  42  and the housing  40 .  
         [0035]    In operation, depressing the pusher arm  72  against the return spring causes the state of the movable contacts  50  relative to the contact pairs  46  or  48  to change from open to close and close to open, respectively. Releasing the arm  72  causes the pusher  54  to return to the normal position under the force of the return spring  56 . The contact springs  52  maintain a bias on the movable contacts  50  so they maintain desired contact with the stationary contacts  46  or  48 .  
         [0036]    The housing  40 , cover  42 , movable contacts  50 , stationary contacts  46  and  48  and contact springs  52  can be used to create a variety of switching arrangements with different make and break configurations and timing by varying the geometry of the pusher  54  and the point about which the pusher  54  pivots.  
         [0037]    Referring to FIG. 4 and  5 , a snap lock  78  is integrally formed with the housing  40  and extends outwardly from the side wall  61 , opposite the openings  62 . The snap lock  78  comprises a planar web  80  extending perpendicularly from the side wall  61  just above its center line relative to the outer wall  60 . As such, when the cover  42  is mounted on the housing  40 , the web  80  is generally centrally located.  
         [0038]    A generally rectangular element  82  is connected on either side of the web  80  into the side wall  61 . A diagonal wall  84  extends around each rectangular wall  82  to define a tenon  86  on each side of the web  80 . A projection  88  is connected to a distal end of the web  80  on each side thereof. Each projection  88  comprises a generally square shaped wall  90  and a generally triangular wall  92 . The square shaped wall  90  and the generally triangular wall  92  extend upwardly from either side of the web  80  and include a common wall. The square shaped wall  90 , opposite the triangular wall  92 , includes an upwardly extending ramp wall  94  to define a shoulder  96 . A blade  98  extends from each side of the web  80  between the tenon  86  and the projecting end  88 .  
         [0039]    Referring to FIGS.  6 - 8 , the main housing base  28  is illustrated. The base  28  is formed of an insulating material which may be plastic.  
         [0040]    The base  28  includes opposite side walls  100  each having a front edge  102 .  
         [0041]    First and second parallel ribs  104  and  106  on each side wall  100  extend from each front edge  102 . The ribs  104  and  106  are in the form of opposite parallelograms to provide facing channels  108  and  110 , see FIG. 7, to define a dovetail mortise  112 . A third rib  114  extends diagonally from the second rib  106  opposite the front edge  102 . The second rib  114  ends in a turned end  116 .  
         [0042]    To mount the contact block  20  to the main housing  26 , the contact block  20  is positioned on the main housing with the pusher arm  72 , see FIG. 3, depressed so that the opening  74  can be located proximate one of the actuator ends  34 . The contact block  20  is then turned so that the projecting end  88  and the blade  98  are located between the ribs  104  and  106 . The contact block  20  is the moved linearly in line with the ribs  104  and  106  and the blade  98  guides the contact block  20  so that the dovetail tenon  86  is received in the dovetail mortise  112  to join the contact block  20  to the main housing  26 . As the contact block  20  is continually moved, the projecting end ramped wall  94  engages the third rib  114  and causes the web  80  to flex outwardly until the projecting end  88  just clears the third rib  114  and snaps in place with the shoulder  98  captured outside the third rib  114  adjacent its turned distal end  116  to provide a snap lock arrangement. As such, the contact block  20  can be snap mounted from in front of the contactor  22 . The contact block  20  can be easily removed by flexing the web  80  outwardly so that the projecting end  88  clears the third rib  114  and then sliding the contact block  20  forwardly and downwardly until the dovetail tenon  86  clears the dovetail mortise  112 .  
         [0043]    Although the mortise and tenon joints described herein are in the form of a dovetail, other configurations of a mortise could be used, as will be recognized by those skilled in the art. Moreover, other joining structures may be used to join the contact block  20  to the main housing  26  in connection with the snap lock  78 .  
         [0044]    By providing the tenon  86 , blade  98  and projecting end  88  on both sides of the web  80 , and by providing the mortise  112  on both sides of the base  28 , the contact block  20  can be mounted on either side of the contactor  22 .  
         [0045]    It can therefore be appreciated that a new and novel system and method for snap mounting a contact block to an actuator apparatus has been described. It will be appreciated by those skilled in the art that, given the teaching herein, numerous alternatives and equivalents will be seen to exist which incorporate the disclosed invention. As a result, the invention is not to be limited by the foregoing exemplary embodiments, but only by the following claims.