Variable resistor construction having spring terminal clips surrounded by a potting agent

Claim 1

A variable resistor comprising a hollow housing member enclosing a resistance substrate having a resistance element thereon, a wiper element, and means for adjusting the position of the wiper element on the resistance element from the exterior to said housing, wherein the improvement comprises: A. said housing being hollow and having an open side thereof for reception of the resistance element and the wiper element, said housing having a continuous, recessed shoulder surrounding the hollow interior thereof, said recessed shoulder being disposed inwardly of the peripheral edges of said housing and facing outwardly from the open end thereof to support a resistance substrate element within said housing, said housing further having at least one recessed, outwardly open terminal receiving cavity opening outwardly from the open end of said housing, said terminal receiving cavity being disposed entirely between said recessed shoulder and the peripheral edge of said housing, said recessed cavity having an imperforate bottom wall recessed into said housing below said recessed shoulder, said recessed shoulder forming a continuous wall isolating said recessed cavity from the hollow interior of the housing, said substrate being disposed on said recessed shoulder and overlying a portion of said recessed cavity, and being disposed in inwardly spaced relation with the outer wall of said recessed cavity to provide a space for entrance of a potting agent into said cavity; B. a resistance substrate element comprising a substantially nonelectrically conducting material, said substrate being shaped to form a cover member for the open side of said housing, said substrate being disposed in said housing and having a portion of the inner face thereof resting on and contacting said recessed shoulder about the entire circumference of the hollow interior of the housing to completely close the interior of the housing; C. said electrical resistance element being disposed on the inner side of said substrate facing the interior of said housing, said wiper element being in electrical engagement with said resistance element; D. a plurality of electrical terminals connected to said resistance element for making electrical connection therewith, each of said electrical terminals comprising an electrically conducting metal having a resilient, channel-shaped spring clip portion and an integral lug portion extending from said spring clip portion, said spring clip portion having a pair of spaced electrically conducting metal legs, the normal unstressed distance between said legs being less than the transverse thickness of said substrate, said substrate being disposed between the legs of said spring clip with one of said legs being urged by resiliency of said spring clip into electrical contact with said resistance element, said spring clip being positioned on the substrate with said one leg thereof disposed entirely on the inner side of said substrate between said recessed shoulder and the peripheral edge of said housing and lying in said recessed cavity, the other leg of said spring clip and said lug portion being disposed entirely on the outer side of said substrate with said lug portion extending away from said substrate and said housing; and E. a solidified, electrically nonconducting potting agent disposed over the outer face of said substrate and filling said recessed cavity in said housing to form a sealed cover for said housing, said potting agent completely surrounding both legs of the spring clip portions of said terminals and said potting agent being disposed about both inner and outer faces of said substrate and covering the region of the electrical contact made by the spring clip portion of said terminals to retain the legs of said spring clips in solid electrical contact with the resistance element and to resist breaking of the electrical contact by vibration of said housing, said potting agent also surrounding the point of emergence of said terminal lugs from said housing to seal said housing from the entrance of foreign matter therein, and said potting agent further sealing said substrate to the inner walls of said housing to form a sealed cover member.