Abstract:
The present invention is related to a pusher assembly ( 105 ) for use with an operator. According to one aspect of the present invention, a pusher assembly generally comprises a body portion ( 208 ); first window ( 216 ) formed in the body portion; second window ( 218 ) formed in the body portion adjacent to the first window, the second window being wider than the first window. According to another aspect of the present invention, a method for assembling a pusher assembly comprises the steps of inserting ( 602 ) a movable contact into a first position in a first window; moving ( 608 ) the movable contact to a second window; and rotating ( 610 ) the movable contact to a second position within the second window.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     The present U.S. patent application having at least one common inventor as 
     U.S. patent application Ser. No.09/961,155 entitled “System and Method for Auxiliary Contact Assembly”, and 
     U.S. patent application Ser. No.09/961,159 entitled “System and Method for Auxiliary Contact Assembly and Snap Mounting”, and 
     U.S. patent application Ser. No.09/961,162 entitled “System and Method for Mounting a Moveable Contact in a Contact Block”, and 
     U.S. patent application Ser. No. 09/961,156 entitled “System and Method for Mounting a Moveable Contact in a Contact Block”, and 
     U.S. patent application Ser. No. 09/961,158 entitled “Contact Block Assembly and Method of Assembling a Contact Block Assembly”, and 
     U.S. patent application Ser. No.09/961,160 entitled “Movable Contact and a Method of Assembling a Pusher Assembly having a Movable Contact”, which are filed with the U.S. Patent and Trademark Office concurrently on Sep. 21, 2001, the entirety of each being incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a pusher used in a contact block, and more particularly to a pusher assembly for receiving a movable contact and a method of assembling a pusher assembly. 
     BACKGROUND OF THE INVENTION 
     Contact block assemblies are often assembled by hand, and often have a number of springs which make the assembly difficult. In particular, when assembling components of a conventional contact block assembly, it may be necessary for an assembler to compress a spring in order to insert another component of the assembly. In such situations, it is often common that the spring becomes dislodged, and in many cases may becomes lost. More importantly, the difficulty in assembling the contact block may cause additional fatigue on a worker and an increase in assembly errors. 
     Such problems are particularly true of pusher assemblies, which often have smaller springs that are more difficult to manipulate with the human hand. In particular, inserting a small spring into a pusher by compressing the spring can be difficult. Further, when a pusher assembly is assembled in a contact block, it is beneficial if the components of the pusher assembly are secured within the pusher assembly. That is, the pusher assembly could be picked up and placed in the contact block housing without any fear that components of the pusher assembly would become dislodged. Accordingly, there is a need for a pusher assembly which is easy to assemble and will stay intact prior to assembly into a contact block. 
     SUMMARY OF THE INVENTION 
     The present invention is related to a pusher assembly for use in a contact block. According to one aspect of the present invention, a pusher assembly generally comprises a body portion, a first window formed in the body portion, and a second window formed adjacent to the first window, wherein the second window is wider than the first window. 
     According to another aspect of the present invention, a method for assembling a pusher assembly comprises the steps of inserting a movable contact into a first position in a first window; moving the movable contact to a second window; and rotating the movable contact to a second position within the second window. 
     It is an object of the invention to provide an improved pusher assembly having a movable contact and a spring. 
     It is a further object of the invention to provide a contact block assembly having an improved pusher assembly. 
     It is a further object of the invention to provide an improved method for assembling a pusher assembly. 
     Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded view of a contact block assembly according to the present invention; 
     FIG. 2 is an exploded view of a pusher assembly according to the present invention; 
     FIG. 3 is a cross-sectional view of the pusher of FIG. 2 taken at lines  3 — 3 ; 
     FIG. 4 is a perspective view of the pusher assembly during a first stage of assembly according to the present invention; 
     FIG. 5 is a perspective view of the pusher assembly at a second stage of assembly according to the present invention; 
     FIG. 6 is a perspective view of the pusher assembly with an incorrectly installed movable contact according to the present invention; and 
     FIG. 7 is a perspective view of the pusher assembly with a correctly installed movable contact according to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning first to FIG. 1, an exploded view of a contact block assembly  100  according to the present invention is shown. The contact block assembly  100  comprises a lower housing  101  for receiving stationary contacts  102  and  103 , and a pusher assembly  104 . The pusher assembly  104  includes a pusher  105 , a movable contact  106  and a contact spring  108 . The contact block assembly  100  further includes stationary contacts  110  and  112 . Although four stationary contacts are shown for a two pole contact block assembly, two stationary contacts could be employed in a one pole contact block assembly, as is well known in the art. Also, the orientation or shape of the stationary contacts could vary, depending upon whether the contact block assembly  100  is configured to be in an “normally open” or “normally closed” arrangement, as is well known in the art. The contact block assembly further includes a return spring  114  and a cover  116 . When the contact block is assembled, a snap  118  is coupled to a complimentary receiving portion  120  to secure the cover  116  to the lower housing  101 . A similar snap (not visible) is coupled to a second receiving portion  122 . Finally, mounting screws  124  and  126  enable stacking of contact block assemblies, or the attachment of an operator, as is well known in the art. 
     The lower housing  101  further includes recesses  130 ,  132 ,  134 , and  136  for receiving the stationary contacts  102 ,  103 ,  110 , and  112 . The lower housing  101  further includes a recess  144  for receiving the pusher assembly  104 . The stationary contact  102  further includes a contact portion  152  and a contact screw  154 . A contact surface  153  is associated with the contact portion  152 . Similarly, a contact portion  156 , a contact surface  157  and a contact screw  158  are shown on the stationary contact  103 . The stationary contact  112  includes a contact  162  and a contact screw  164 , while the stationary contact  110  includes a contact  166  and a contact screw  168 . Contact surfaces (not visible) are formed on the underside of contacts  162  and  166 . The return spring  114  extends from a first end  172  to a second end  174 . Finally, cover  116  includes openings  182 ,  184 ,  186 , and  188  for enabling access to contact screws  154 ,  158 ,  164 , and  168 . Also, an opening  190  and threaded portions  192  and  194  enable the coupling of multiple contact block assemblies, as is well known in the art. 
     Turning now to FIG. 2, an exploded view of the pusher assembly  104  is shown. The pusher  105  comprises a body portion  208  which includes an upper portion  210  having a recess  212  formed at a first end of the pusher  105 , as shown at the top in the orientation of FIG.  2 . The recess  212  enables an easy loading of the contact spring (i.e. the contact spring does not need to be compressed to be loaded into the pusher  105 , but merely dropped into the recess  212 ). A window  214  is also formed in a side of the pusher  105 , and extends through the back side (not visible). The window  214  includes an entry window portion  216  and a main window portion  218 . The entry window portion  216  is long enough and wide enough to receive the movable contact  106  in the orientation shown in FIG. 2, as will be described in more detail in reference to the remaining figures. Similarly, the main window portion  218  is long enough and wide enough to allow the rotation of the movable contact  106  to a second orientation, such as the orientation shown in FIG.  5 . The positioning of the entry window portion  216  and the main window portion  218  adjacent to each other creates shoulder portions  219  as shown in FIG.  2 . The assembly of the pusher assembly  104  will be described in more detail in reference to FIGS. 4 and 5. 
     The pusher assembly  105  further includes a lower body portion  220  having a ledge  222  and a lower recess  224 . The spring  108 , which extends from a first end  226  to a second end  228 , is generally inserted through the recess  212  into the lower recess  224 . Finally, pusher  105  includes a first mounting arm  230  having a ledge  231  and a second mounting arm  232  having a ledge  233 . The mounting arms  230  and  232  further include guides  234  and  235  respectively for receiving and properly positioning the return spring  114 . 
     The mounting arms  230  and  232  may be of a different size and/or shape to prevent an inadvertent error in inserting the pusher assembly into a contact block housing. In particular, by forming the first mounting arm  230  and the second mounting arm  232  of different shapes, the incorrect insertion of the pusher assembly into a contact block assembly could be avoided. 
     The movable contact  106  comprises a body portion  242  which is substantially flat. The flat body portion of the movable contact further enables an easy assembly of the pusher. As will be described in detail in reference to FIGS. 4 and 5, the movable contact  106  is easily moved into the main window portion  218  because the contact spring  108  is retained in the lower recess  224 . Any compression of the contact spring  108  into the recess will not cause the contact spring  108  to become dislodged from the lower recess  224 . The body portion being substantially flat on both sides also enables mounting for both normally open and normally closed configurations. 
     The movable contact also has a first flange  244  extending from a first side and a second flange  245  extending from a second side. The movable contact  106  includes a second set of flanges including a third flange  246  extending from the first side and a fourth flange  247  extending from the second side. Flanges  244  through  247  are generally included to retain the movable contact  106  within the pusher  105 . Although four flanges are shown, two flanges could be used to retain the movable contact  106  within the pusher  105 . While the flanges as shown are symmetric, the number, shape and/or orientation of flanges could be chosen to prevent the improper insertion of the movable contact  106  into the pusher  105 . 
     The movable contact  106  further includes a first contact element  248  extending from a first end of the body portion  242 . The first contact element  248  includes a first finger  250  having a fulcrum portion  252 , an inclined portion  254 , and a contact portion  256 . The contact portion includes a contact surface  258 . The contact surface could be composed of any conducted material, such as silver, applied by plating, bonding, soldering or some other suitable method. A slot  259  separates the first contact finger  250  from a second contact finger  260 . The second contact finger  260  comprises a fulcrum portion  262 , an inclined portion  264 , and a contact portion  266 , also having a contact surface  268 . 
     A second contact element  269  extending from a second end of the movable contact includes a third finger  270  having a fulcrum portion  272 , an inclined portion  274 , and a contact portion  276  having a contact surface  277 . A slot  278  separates the third contact finger  270  from a fourth contact finger  280 . Similarly, the fourth contact finger includes a fulcrum portion  282 , an inclined portion  284 , and a contact portion  286  having a contact surface  287 . The inclined portions provide an offset which allows for an easy test to confirm correct installation, as will be described in reference to FIGS. 6 and 7. 
     Turning now to FIG. 3, a cross-section of the pusher  105  is shown. As is more clear in this cross-section, the entry window portion  216  and the main window portion  218 , as shown, extend through the upper body portion  210 . Also shown is recess  212  extending through the top of the upper body portion  219  to recess  224  in the lower body portion  220  for receiving the contact spring  108 . 
     Turning now to FIGS. 4 and 5, the method of assembly of the pusher assembly  104  is shown. In particular, the movable contact  106  is inserted into the upper window portion  216  in the vertical position as shown in FIG.  4 . The movable contact is then moved downward, compressing the contact spring  108 . When the side of the movable contact  106  having flanges  245  and  246  clears the lower end of the entry window portion  216  at the shoulder portions  219 , the movable contact  106  is then rotated into a horizontal position as shown in FIG.  5 . The force of the contact spring  108  urges the movable contact  106  to a resting position against the shoulders  219 . That is, the body portion makes contact with the shoulders  219 . As also can be see in FIG. 5, the flanges  246  and  247  extend beyond the main window portion  218  preventing any lateral movement of the movable contact  106  within the main window portion  218 . The flanges  244  and  245  also prevent any lateral movement of the movable contact  106  in the opposite direction. 
     The assembled pusher assembly  104  shown in FIG. 5 provides considerable advantage in the assembly of a contact block assembly shown in FIG.  1 . In particular, once the pusher assembly  105  is assembled, an assembler of the contact block assembly  100  need not worry that the movable contact  106  or the contact spring  108  will become dislodged during assembly. Similarly, the pusher assembly  104  could be assembled prior to any assembly of the contact block assembly  100 , providing flexibility in assembling the contact block assembly  100 . While the movable contact  106  was rotated to the horizontal position shown in FIG. 5, the movable contact could be rotated in the other direction so that the movable contact  106  is in the opposite orientation, depending upon the design of the contract block assembly. Although only a single movable contact block assembly is shown, it will be understood that two movable contacts, placed back-to-back, may be inserted into the pusher. Finally, while the movable contact  106  is shown resting against the shoulders  219 , the movable contact may not be resting against the shoulders when the contact block assembly  100  is assembled or operated. 
     Turning now to FIGS. 6 and 7, a perspective view of the assembled components  115  shows the benefit of the movable contact according to the present invention. As shown incorrectly inserted in FIG. 6, the movable contact fails to make a contact with any stationary contact. During a simple test, it would be easy to determine whether the movable contact is incorrectly inserted. When correctly inserted as shown in FIG. 7, the movable contact clearly makes contact with the stationary contacts. Accordingly, the movable contact of the present invention provides a significant advantage during the assembly process of a pusher assembly by allowing detection of an incorrectly inserted movable contact. 
     It can therefore be appreciated that a new and novel system and method for a pusher assembly has been described. It will be appreciated by those skilled in the that, given the teaching herein, numerous alternatives and equivalent 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.