Rod-in-tube actuated temperature sensing device

Claim 1

A MINIATURE THERMOSTATIC SWITCH ESPECIALLY ADAPTED FOR USE IN A TEMPERATURE CONTROL SYSTEM FOR A SMALL ELECTRIC MOTOR, OR THE LIKE; SAID SWITCH COMPRISING A BASE OF ELECTRICALLY INSULATING MATERIAL, AN ELONGATED RESILIENT SNAP SPRING OF ELECTRICALLY CONDUCTING MATERIAL SUPPORTED AT ONE END THEREOF ON ONE SIDE OF SAID BASE, FIRST AND SECOND SPACED STOP MEMBERS MOUNTED ON SAID ONE SIDE OF SAID BASE IN POSITIONS SUCH THAT THE FREE END OF SAID SNAP SPRING IS DISPOSED THEREBETWEEN, A FIRST ELECTRICAL CONNECTION TO SAID SNAP SPRING, A SECOND ELECTRICAL CONNECTION TO SAID FIRST STOP MEMBER, SAID SNAP SPRING BEING INITIALLY LOCALLY DEFORMED IN A MANNER TO RENDER AT LEAST A PORTION THEREOF CONCAVO-CONVEX IN CROSS-SECTION TO FORM AN AREA WHICH IS SENSITIVE TO PRESSURE FOR MOVING THE FREE END OF SAID SNAP SPRING FROM A FIRST REST POSITION AGAINST SAID FIRST STOP MEMBER TO A SECOND ACTUATED POSITION AGAINST SAID SECOND STOP MEMBER, SAID FREE END OF SAID SNAP SPRING NORMALLY BEING IN CONTACT WITH SAID FIRST STOP MEMBER TO COMPLETE AN ELECTRICAL CIRCUIT BETWEEN SAID ELECTRICAL CONNECTIONS AND BEING MOVABLE INTO CONTACT WITH SAID SECOND STOP MEMBER TO INTERRUPT SAID ELECTRICAL CIRCUIT UPON THE APPLICATION OF A PREDETERMINED FORCE TO SAID SENSITIVE AREA, A TUBE HAVING ONE END THEREOF MOUNTED ON SAID BASE AND EXTENDING OUTWARDLY THEREFROM FROM THE OTHER SIDE THEREOF GENERALLY PARALLEL TO THE PATH OF MOVEMENT OF SAID SPRING AND FORMED OF A METAL HAVING A FIRST COEFFICIENT OF THERMAL EXPANSION, A ROD DISPOSED IN SAID TUBE AND HAVING ONE END THEREOF THERMALLY AND MECHANICALLY CONNECTED TO THE OTHER END OF SAID TUBE AND HAVING THE OTHER END THEREOF EXTENDING OUTWARDLY BEYOND SAID ONE SIDE OF SAID BASE AND HAVING A SECOND COEFFICIENT OF THERMAL EXPANSION LESS THAN SAID FIRST COEFFICIENT OF THERMAL EXPANSION, A LEVER FORMED OF HEAT INSULATING AND ELECTRICAL INSULATING MATERIAL HAVING ONE END THEREOF PIVOTALLY SUPPORTED BY SAID BASE AND THE OTHER END THEREOF SUPPORTED ON SAID SENSITIVE AREA OF SAID SNAP SPRING, SAID LEVER EXTENDING GENERALLY PERPENDICULAR TO SAID TUBE AND SAID ROD AND GENERALLY PARALLEL TO SAID SPRING, AND MEANS INTERCONNECTING THE OTHER END OF SAID ROD AND SAID LEVER FOR PIVOTING THE LEVER RELATIVE TO SAID ROD IN RESPONSE TO THE RELATIVE MOVEMENT BETWEEN SAID BASE AND THE OTHER END OF SAID ROD TO APPLY THE PREDETERMINED FORCE TO SAID SENSITIVE AREA OF SAID SNAP SPRING FOR OPERATING THE FREE END OF SAID SNAP SPRING BETWEEN THE REST AND ACTUATED POSITIONS THEREOF WHILE MAINTAINING THERMAL AND ELECTRICAL INSULATION BETWEEN SAID ROD AND SAID SNAP SPRING, THE SENSITIVE AREA OF SAID SPRING BEING LOCATED BETWEEN SAID OTHER END OF THE LEVER AND SAID BASE, THE FREE END OF SAID SPRING BEING SPACED FROM THE AXIS OF SAID ROD AND TUBE IN A DIRECTION PERPENDICULAR TO SUCH AXIS BY A DISTANCE GREATER THAN SUCH SPACING OF SAID OTHER END OF SAID LEVER.