Electrical heater having a snap-in base plate

Claim 1

IN AN ELECTRIC HEATER, THE COMBINATION OF A CYLINDRICALLY SHAPED CASE HAVING ONE CLOSED END AND AN INNER CIRCUMFERENTIALLY EXTENDING GROOVE FORMED IN THE CASE PARALLEL TO AND ADJACENT BUT SPACED FROM AN OPEN END OF THE CASE, A HEATING ELEMENT INCLUDING A CARRIER CORE POSITIONED INSIDE SAID CASE, INSULATION MEANS SURROUNDING SAID HEATING ELEMENT AND ITS CARRIER CORE AND HOLDING THEM IS PROPER RELATION TO THE CASE, AND A RESILIENT SPRING METAL PLATE POSITIONED INSIDE SAID CASE WITH ITS OUTSIDE CIRCUMFERENTIAL AND PERIPHERAL EDGE CONTINUOUSLY ENGAGED WITH SAID GROOVE, SAID METAL PLATE HAVING A GREATER DIAMETER THAN THE MINIMUM DIAMETER OF SAID GROOVE AND BEING OF A CONVEX SHAPE ON ITS INNER SURFACE AND A CONCAVE SHAPE ON ITS OUTER SURFACE, SAID METAL PLATE BEING PERMANENTLY POSITIONED WITHIN SAID CASE AND BEING POSITIONED WITH RESPECT TO SAID HEATING ELEMENT AND SAID CARRIER CORE SO THAT THE METAL PLATE CANNOT BE FORCED INWARDLY IN AN AMOUNT SUFFICIENT TO RELEASE THE PERIPHERAL EDGES OF THE METAL PLATE FROM THE GROOVE.