Burner safety control system

Claim 1

A FUEL AND IGNITION CONTROL SYSTEM WHICH COMPRISES THE FOLLOWING ELEMENTS: A MAIN FUEL BURNER LOCATED IN A COMBUSTION ZONE, ELECTRO-RESPONSIVE VALVE MEANS FOR REGULATING THE FLOW OF FUEL TO SAID BURNER, A PILOT BURNER DISPOSED IN IGNITING RELATION TO SAID MAIN FUEL BURNER, ELECTRO-RESPONSIVE VALVE MEANS FOR REGULATING THE FLOW OF FUEL TO SAID PILOT BURNER, IGNITING MEANS ELECTRICALLY ACTUATED AND DISPOSED IN IGNITING RELATION TO SAID PILOT BURNER, A FLAME SWITCH DISPOSED IN FLAME DETECTING RELATION TO SAID BURNERS AND OPERATIVELY CONNECTED TO A FIRST NORMALLY CLOSED SWITCH AND A SECOND NORMALLY OPEN SWITCH, A FIRST THERMO-RESPONSIVE SWITCH HAVING A NORMALLY CLOSED FIRST CONTACT AND A NORMALLY OPEN SECOND CONTACT, A THERMAL DEVICE FOR ACTUATION OF SAID FIRST THERMORESPONSIVE SWITCH, A SECOND THERMO-RESPONSIVE SWITCH HAVING A NORMALLY CLOSED CONTACT, A THERMAL DEVICE FOR ACTUATION OF SAID SECOND THERMORESPONSIVE SWITCH, AN ELECTRO-RESPONSIVE RELAY OPERATIVELY CONNECTED TO A FIRST NORMALLY CLOSED SWITCH AND A SECOND NORMALLY OPEN SWITCH, A RESISTANCE ELEMENT BRIDGING SAID FIRST NORMALLY CLOSED SWITCH, CIRCUIT MEANS OPERATIVELY CONNECTING SAID ELEMENTS TO EACH OTHER AND TO A SOURCE OF ELECTRICAL POTENTIAL SO THAT THE FLOW OF ELECTRIC CURRENT THROUGH SAID SECOND THERMO-RESPONSIVE SWITCH AND SAID FIRST NORMALLY CLOSED SWITCH OF SAID ELECTRO-RESPONSIVE RELAY ACTUATES SAID ELECTRO-RESPONSIVE VALVE MEANS TO PERMIT A FLOW OF FUEL TO SAID PILOT BURNER AND A CONCOMITANT FLOW OF ELECTRIC CURRENT THROUGH SAID IGNITER IGNITES SAID PILOT BURNER, THE FLAME SWITCH ACTUATED BY TEH FLAME FROM SAID IGNITED PILOT BURNER OPENING SAID NORMALLY CLOSED FIRST SWITCH AND CLOSING SAID NORMALLY OPEN SECOND SWITCH, THE OPENING OF SAID NORMALLY CLOSED FIRST SWITCH INTERRUPTING THE FLOW OF ELECTRIC CURRENT THROUGH SAID ELECTRO-RESPONSIVE RELAY AND CAUSING SAID FIRST NORMALLY CLOSED RELAY SWITCH TO OPEN AND SAID SECOND NORMALLY OPEN RELAY SWITCH TO CLOSE WHEREUPON CURRENT CONTINUES TO FLOW THROUGH SAID ELECTRO-RESPONSIVE VALVE MEANS, REGULATING THE FLOW OF FUEL TO SAID PILOT BURNER THROUGH SAID RESISTANCE ELEMENT HOLDING IT IN THE OPEN POSITION AND ALLOWING CURRENT TO FLOW THROUGH SAID THERMAL DEVICE OF SAID FIRST THERMO-RESPONSIVE SWITCH THEEBY ACTUATING SAID SWITCH TO OPEN SAID FIRST NORMALLY CLOSED CONTACT AND CLOSE SAID SECOND NORMALLY OPEN CONTACT, THE CLOSING OF THE SECOND CONTACT PERMITTING THE FLOW OF ELECTRIC CURRENT TO ACTUATE SAID ELECTRO-RESPONSIVE VALVE MEANS ALLOWING A FLOW OF FUEL TO SAID MAIN BURNER WHICH IS IGNITED BY SAID PILOT BURNER, THE ELEMENTS ALSO BEING OPERATIVELY CONNECTED SO THAT THE ABSENCE OF FLAME FROM SAID BURNERS ACTUATES SAID FLAME SWITCH SO AS TO INTERRUPT THE FLOW OF ELECTRIC CURRENT THROUGH SAID IGNITER, BOTH ELECTRO-RESPONSIVE VALVE MEANS, AND SAID THERMAL DEVICE FOR SAID FIRST THERMO-RESPONSIVE SWITCH FOR A PERIOD OF TIME SUFFICIENT TO PURGE ANY UNBURNED FUEL FROM SAID COMBUSTION ZONE.