Control switch for an electrical heating appliance

Claim 1

A CONTROL DEVICE FOR AN ELECTRIC HEATING APPARATUS, COMPRISING A HOLLOW BODY ADAPTED TO BE EVACUATED AND PARTLY FILLED WITH A LIQUID, AN ELECTRIC HEATING COIL LOCATED WITHIN SAID BODY AND SERVING FOR THE EVAPORATION OF THE LIQUID, A RESILIENT MEMBER, MEANS CONNECTING SAID RESILIENT MEMBER WITH SAID HOLLOW BODY, WHEREBY SAID RESILIENT MEMBER IS ELASTICALLY DEFORMED IN ACCORDANCE WITH VAPOR PRESSURE PREVAILING IN THE INTERIOR OF SAID HOLLOW BODY, A SWITCH MEMBER, MEANS CONNECTING SAID SWITCH MEMBER WITH SAID RESILIENT MEMBER, MEANS ELECTRICALLY CONNECTING SAID SWITCH MEMBER WITH SAID HEATING COIL, WHEREBY THE SUPPLY OF CURRENT TO SAID HEATING COIL IS SWITCHED ON AND OFF ACCORDING TO THE DEGREE OF DEFORMATION OF THE RESILIENT MEMBER, A LEAF SPRING SUPPORTING SAID RESILIENT MEMBER, SAID LEAF SPRING RESTING ON BOTH ITS ENDS AND HAVING TWO SUPPORT POINTS, GUIDE CAMS LOCATED AT SAID TWO SUPPORT POINTS AND HAVING CURVED ABUTMENT FACES FOR SAID LEAF SPRING, WHEREBY UPON FLEXURE OF SAID LEAF SPRING CAUSED BY EXPANSION OF SAID RESILIENT MEMBER SAID GUIDE CAMS EFFECT A SHORTENING OF THE EFFECTIVE LENGTH OF THE SPRING BY DISPLACING THE SUPPORT POINTS THEREOF SO THAT THERE IS A PROGRESSIVE STIFFENING OF THE RESILIENT MEMBER WITH INCREASING PRESSURE IN THE INTERIOR OF THE HOLLOW BODY SUCH AS TO CAUSE THE SPRING CHARACTERISTIC TO FOLLOW THE CHARACTERISTIC OF THE CHANGE OF VAPOR PRESSURE WITH TEMPERATURE.