Control of fuel and air supply to burners

Claim 1

APPARATUS FOR THE CONTROL OF FUEL AND AIR SUPPLY TO AN OIL OR GAS BURNER COMPRISING DELIVERY MEANS FOR DELIVERING FUEL AND AIR TO THE BURNER, A FIRST CONTROL MEANS OPERABLE TO VARY THE RATE DELIVERY OF SAID FUEL AND AIR IN THE SAME SENSE, IN ACCORDANCE WITH THE OUTPUT REQUIRED OF THE PART WITH WHICH THE BURNER IS ASSOCIATED, AND A SECOND CONTROL MEANS COMPRISING AT LEAST ONE ELECTRICAL BRIDGE CIRCUIT INCLUDING A RESISTOR OF RELATIVELY HIGH RESISTANCE TEMPERATURE CO-EFFICIENT LOCATED IN ONE SIDE OF SAID BRIDGE CIRCUIT AND DISPOSED IN THE AIR STREAM TO THE BURNER SO THAT ITS TEMPERATURE IS EFFECTED THEREBY, A RELAY DEVICE ASSOCIATED WITH THE RESPONSIVE TO CHANGES IN THE CONDITION OF BALANCE OF SAID BRIDGE CIRCUIT, A THIRD CONTROL MEANS CONTROLLED BY SAID RELAY DEVICE AND CONTROLLING THE RELATIONSHIP BETWEEN THE FATE OF FUEL SUPPLY AND AIR SUPPLY TO THE BURNER, SAID SECOND CONTROL MEANS INCLUDING VALVE APPARATUS CONTROLLING THE AIR SUPPLY TO THE BURNER AND A SERVO MOTOR ACTUATING SAID VALVE APPARATUS AND CONTROLLED BY SAID RELAY DEVICE, SAID RELAY DEVICE COMPRISING DIFFERENTIAL ELECTROMAGNETIC APPARATUS ARRANGED IN THE BRIDGE CIRCUIT AND INCLUDING AN ARMATURE WHEREBY CHANGES IN THE STATE OF BALANCE OF THE BRIDGE CIRCUIT IN ONE SENSE OR THE OTHER WITH CHANGES IN THE CONDITION OF AIR FLOW AND HENCE THE TEMPERATURE OF THE RESISTOR SUBJECT TO THE AIR FLOW CAUSE SAID ARMATURE TO MOVE SELECTIVELY FROM AN EQUILIBRIUM POSITION IN ONE DIRECTION OR THE OTHER TO CLOSE THE APPROPRIATE ONE OF TWO ELECTRIC CIRCUITS AND THUS CAUSE OPERATION OF THE SECOND CONTROL MEANS IN ONE SENSE OR THE OTHER TO RESTORE THE FUEL AND MASS AIR FLOW TO THE DESIRED PROPORTIONS, A POTENTIOMETER IN SAID BRIDGE CIRCUIT AND AN INTERCONNECTION BETWEEN SAID POTENTIOMETER AND SAID SECOND CONTROL MEANS TO RESTORE THE BRIDGE CIRCUIT TO THE DETERMINED CONDITION OF BALANCE SIMULTANEOUSLY WITH OPERATION OF SAID SECOND CONTROL MEANS TO RESTORE THE FUEL AND MASS AIR FLOW TO THE DESIRED PROPORTIONS.