Abstract:
A poke-in contact modular assembly for a printed circuit board that has a solderless connection with a junction box. The assembly allows for easier and more efficient removal and replacement of the printed circuit board and electrical components. In addition, the poke-in contact is configured to reduce the amount of normal force applied to the printed circuit board when wire tabbing is inserted into the contacts.

Description:
BACKGROUND OF THE INVENTION 
     The present invention is directed to an improved system and method for securing electronics in a junction box. More specifically, the present invention is directed to a contact assembly for securing electronics in a junction box without the use of tools or other equipment. 
     Most commonly, current systems use fragile electronics disposed in the junction boxes. The electronic components are unable to sustain the forces of inserting wire tabbing into the connections within the junction box. Often times the electronics are damaged or the solder connections are broken from the force of repeatedly inserting and removing the wire tabbing into the junction box. One current system redesigned the typical junction box by adding a second capsule around the body section of the entire contact body to help remedy the issue of the force when inserting the wire tabbing. The second capsule provides extra support and strength to withstand the normal force from inserting the wire tabbing into the junction box when making an electrical connection. However, this system requires more materials for manufacture, is more expensive and requires a longer assembly time. 
     Other current methods eliminate the second outer capsule discussed above, where the junction box is constructed of material strong enough to withstand the normal force applied during insertion of the wire tabbing. However, in order to maintain a solid connection with the wire tabbing, these systems require the aid and use of tools or equipment to initiate the connection with the wire tabbing. The use of the tools and equipment to make the connection is time consuming, as well as expensive. In addition, often times, these tool connections are permanent and prevent the replacement of any of the components. 
     In addition, the wire tabbing used to make electrical connections with the electronics within the junction box are connected with a solder connection which is time consuming and expensive when both designing and repairing the system. 
     Thus, what is needed is a system that is configured with a receptacle that is capable of receiving wire tabbing and strong enough to withstand the normal force of insertion. A system that allows for easy repairs and replacement when necessary to reduce time and costs is needed as well. 
     SUMMARY OF THE INVENTION 
     An embodiment of the present invention includes a connector assembly for receiving an electrical component having a base, and a plurality of pin tails extending in a substantially perpendicular direction away from the base. The pin tails connect to a printed circuit board. The connector assembly also has a plurality of walls extending from the base in an opposed direction of the plurality of pin tails and a top extending between the plurality of walls and substantially parallel to the base. Further, the connector assembly has a lance extending from the top having an arcuate back end, a contact beam that extends parallel to the base, a front section at a preselected angle to the contact beam and at least one protrusion extending from a side of the front section. The electrical component is manually inserted into the connector assembly with an insertion force, pressing against the front section, which moves upon insertion of the electrical component. Upon displacement, the contact beam touches the base to complete an electrically conductive connection, and the electrical component is secured in the connector until a force is applied to the at least one protrusion extending from the side of the front section. 
     Another embodiment of the present invention includes a poke-in contact assembly having a base, a plurality of pin tails extending in a substantially perpendicular direction away from the base and secured to a printed circuit board, a plurality of walls extending from the base in an opposed direction of the plurality of pin tails and a top extending between the plurality of walls and substantially parallel to the base. The contact assembly also has a lance disposed to extend from the top having an arcuate back end, a contact beam that extends parallel to the base and a front section disposed at a preselected angle to the contact beam, and at least one protrusion extending from a side of the front section. An electrical component is manually inserted into the connector assembly, pressing against the front section, which moves upon insertion of the electrical component, and upon displacement, the contact beam touches the base to complete an electrically conductive connection. The lance exerts an equal and opposite reactive force upon the electrical component to secure the electrical component in the connector assembly and the electrical component is secured in the connector until a force is applied to the at least one protrusion extending from the side of the front section. 
     One advantage of the present invention is the lower manufacturing, replacement and maintenance costs of the system. 
     Yet another advantage of the present invention is improved replaceability functionality. 
     Another advantage of the present invention is that no tools or equipment are necessary to electrically connect the wire tabbing in the poke-in contact. 
     Yet another advantage of the present invention is that no support apparatuses are required for the contact. 
     Another advantage of the present invention is high retention of the contact. 
     Another advantage of the present invention is that the present invention can replace the circuitry in current systems with little or substantially zero modifications to the circuitry exterior to the junction box. 
     Yet another advantage of the present invention is low normal force applied during insertion of the wire tabbing into the poke-in contact. 
     Another advantage of the present invention is the locking mechanism of the lance once the wire tabbing is inserted into the poke-in contact. 
     Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates a perspective view of the top of the present invention. 
         FIG. 1B  illustrates a perspective view of the bottom of the present invention. 
         FIG. 1C  illustrates a surface area view of the present invention. 
         FIG. 1D  illustrates a cross sectional view of the contact of the present invention. 
         FIG. 2  is a graphical analysis of the reaction force of the poke-in contact. 
         FIG. 3  is a graphical analysis of the stress upon the contact of the present invention. 
     
    
    
     Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is directed to a poke-in contact mount assembly that reduces the normal forces sustained by the circuit board and components during insertion of the wire tabbing into the junction box. 
       FIGS. 1A ,  1 B,  1 C and  1 D illustrate various views of the poke-in contact  10  used in the present invention. As shown in  FIGS. 1A and 1B , the poke-in contact  10  includes a base section  51 , with generally upstanding wall sections  52  that extend perpendicular and upward from the base  51  to form parallel opposite walls. Parallel to the base  51  and connected on the opposite end of the wall sections  52  than the base  51 , a top section  54  extends and spans the distance between both wall sections  52 . The base  51 , wall sections  52  and top section  54  form a box-like structure, having four defined areas connecting to enclose a space. Extending from the top section  54  and wrapping around in an arcuate shape, a locking lance  30  contains three portions, a back section  56 , a contact beam  50  and a front section  58 . The back section  56  forms a hemi circular shape similar in cross-section to a half circle before it transitions into the contact beam  50 . The contact beam  50  is adjacent to and parallel to the base  51 , but not contacting the base  51 . The contact beam  50  extends the entire length of the base  51  and turns upward forming a front section  58  that angles in toward the center of the poke-in contact  10 . The front section  58  preferably rests at an angle of approximately forty-five degrees from the contact beam  50 , but any other suitable angle may be used. The poke-in contact  10  can be constructed of copper, a copper alloy, or any other suitable material that is electrically conductive, substantially flexible to accept an insert, while being substantially sturdy and rigid to provide retention when force is applied. The alloy may be of thickness of about 0.35 mm thick, but can be constructed with any thickness suitable for the contact  10  to operate correctly with the required retention. 
       FIG. 1A  illustrates a perspective view of the top of the poke-in contact assembly  10 . On each of the wall sections  52 , a wall aperture  38  is located, where a portion of the locking lance  30  protrudes. The protrusion  40  of the locking lance  30  through this wall aperture  38  provides the ability to deflect the lance  30  with a tool or utensil when necessary to remove the wire or conductive material that is secured in the poke-in contact  10 . The wall apertures  38  also acts as a check device to ensure that the front section  58  of the lance  30  is not displaced to an angle that would cause damage to the lance  30 . 
       FIG. 1B  illustrates a perspective view of the bottom of the contact  10 . The solder pin tails  18  are disposed to secure the contact  10  to the printed circuit board  12  by a solder connection or other suitable connection.  FIG. 1C  illustrates the surface area and shape of the present invention in an intermediate form, as the assembly is initially stamped from sheet stock. The wall apertures  38  are shown, along with the protrusions  40  on the lance  30 . In addition the solder pin tails  18  are also disposed along the edges of the contact  10 .  FIG. 1C  shows the poke-in contact  10  being of unitary construction and stamped to form the base  51 , walls  52 , top  54 , and lance  30  of the contact  10  as depicted in  FIGS. 1A and 1B . It should be known that the poke-in contact may also be manufactured and assembled from more than one unitary piece. 
       FIG. 1D  illustrates a cross sectional view of the poke-in contact  10  of  FIG. 1A . The printed circuit board  12  receives the solder pin tails  18  of the contact  10 , where they are secured into place by solder or other similar connection. A wire tabbing  42  enters the poke-in contact  10  by pushing against the front section  58  of the lance  30 . The front section  58  of the lance  30  deflects to receive the wire tabbing  42  by displacing the contact beam  51  toward the base  28  of the contact  10  while maintaining a firm tension on the wire tabbing  42  to secure the wire tabbing  42  in place. When an opposite force is applied to the wire tabbing  42 , such as a force to remove the tabbing  42  from the lance  30 , the lance  30  provides a preselected range of retention, preferable ten to fifteen pounds. The force can be adjusted by angle selection, material selection, material thickness and the size of the contact  10 . In effect, as resistance is created against the lance  30 , the lance  30  responds with a greater force, an equal and opposite force against the tabbing, to secure the wire up to fifteen pounds of force. To easily and quickly remove the tabbing  42  from the contact, a tool such as a screwdriver, a similar device or other suitable tool can be used to contact the protrusions  40  of the lance  30 , releasing the contact of the lance  30  and the tabbing  42 , and allowing the tabbing  42  to retract from the contact  10 . The protrusions  40  are forced away from the top  54  by the tabbing  42 , creating a space between the wire tabbing  42  and the front section  58  of the lance  30  and allowing the wire tabbing  42  to be removed with no reaction force applied by the lance  30 . The inserted structure is not limited to tabbing as shown and can include wire. 
       FIG. 2  graphically illustrates the reaction force during displacement of the lance  30  on a wire tabbing  42  inserted into the contact  10 . As shown in portion  70  of  FIG. 2 , the displacement of the lance  30  is relatively low and constant. Before the wire tabbing  42  is inserted into the poke-in contact  10 , the contact beam  50  is not in contact with the base  51  of the poke-in contact  10  (See  FIG. 1D ). As the wire tabbing is inserted into the lance  30 , the front end  58  of the lance  30  moves inwardly and downwardly toward the contact beam  50 . The lance  30  displaces downward as the wire tabbing is inserted until the contact beam  50  touches the base  51  of the poke-in contact  10 . The displacement downwardly is limited by the base  51  and causes the end  58  to exert a force against the tabbing  42 . As shown at point  76  in  FIG. 2 , the reaction force and displacement increases as more force is applied to insert the wire tabbing  42  into the poke-in contact  10 . Once the contact beam  50  is in full contact with the base  51  of the poke-in contact  10 , the front end  58  of the lance  30  begins to compress and displace as the contact beam  50  and back section  56  do not displace any further. The maximum force and displacement the lance  30  can endure without breaking is shown at point  74  in  FIG. 2  which is the course related to the ultimate tensile strength (UTS) of the material selected. It is preferred to maintain displacement that is less than the UTS to prevent deformation of the lance and the contact. The lance  30  will remain at the maximum displacement (shown by point  74 ) until the protrusions  40  of the lance  30  are released, and the wire tabbing  42  is removed. Section  72  in  FIG. 2  shows the reduction in displacement and reaction force as the wire tabbing  42  is removed from the lance  30 . 
       FIG. 3  illustrates the stresses on the locking lance  30  during insertion of the wire tabbing  42 . The analysis was taken during insertion of a wire tabbing (not shown) where the maximum stress is applied to the lance  30 . In the uncompressed position, when the contact  10  is not receiving wire tabbing, and no stresses are placed on the lance  30  and the contact beam  50  is not in contact with the base  51  of the contact  10 . Only when the wire tabbing  42  is inserted into the lance  30  do sufficient stresses begin to occur to move the contact beam  50  into contact with the base  51  in a terminal connection. The back section  56  of the lance  30  does not sustain any stresses, as the normal force of the wire tabbing is inserted into the lance  30  is resolved as a vertical force and is applied in the front section  58  of the lance  30  closest to the wire tabbing  42  and in the area of the lance  30  that is flexing the most. The normal force of the wire tabbing  42  being inserted into the contact  10  by pushing down on the lance  30  results in stresses at the front side  58  of the lance  10  and pushes the contact beam  50  downward to make a terminal connection to the base  51  below. 
     The poke-in contact assembly provides a secure connection for wire tabbing that does not require the use of tools or other utensils when inserting. The lance of the poke-in contact displaces upon insertion of the wire tabbing and absorbs the majority of the force applied by the tabbing, thereby reducing the amount of force applied to the printed circuit board or other device the contact is mounted to. In addition, the poke-in contact applies a force or retention when the tabbing is forced outward from the poke-in contact without the use of tools or other utensils. To effectively remove the tabbing from the contact, a tool or utensil is used to depress the lance and release the tabbing and the force applied to the tabbing by the lance. 
     While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.