US 4,432,722 AGranted

Interrupted power hot wire gas ignition control system

AssigneeHoneywell Inc.

InventorsJohn E. Bohan, Jr., Brian J. Hinton

Life of this patent

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Abstract

A hot wire type of gas ignition system uses a negative temperature coefficient resistor-ignitor element that is deenergized after ignition has occurred. The ignition and safety monitoring of the circuit is accomplished by a second flame detector means, and the flame responsive circuit that has been disclosed in a flame rectification circuit.

Claims10

Dependent claims

An interrupted power hot wire gas ignition control system adapted to control a burner having gas valve means incorporating a pilot valve and a main valve, including:

a negative temperature coefficient resistor-ignitor element which when energized from a potential changes in resistance value as the resistor-ignitor element heats to an ignition temperature with said element mounted at said burner;
a series ignition circuit including a normally closed relay contact, a resistor, and said resistor-ignitor element with said ignition circuit adapted to be connected to a source of potential upon operation of said burner;
switch means connected to energize said pilot valve;
switch control circuit means connected to said resistor to control said switch means, and wherein said switch means is nonconductive when said resistor-ignition element is cold, and further wherein said switch means is conductive to energize said pilot valve when said resistor-ignition element is at a gas ignition temperature;
flame detector means mounted at said burner to detect the presence of a flame when said pilot valve has opened with said resistor-ignitor element at said gas ignition temperature;
flame responsive circuit means having an input connected to said flame detector means, and said flame responsive circuit means having switched output means;
said switched output means including a relay having a normally open relay contact, and further including said normally closed relay contact;
said normally open relay contact connected to said main valve to allow said normally open relay contact when closed to energize said main valve;
and impedance means including a diode connecting said pilot valve to said normally open relay contact;
said relay being energized upon the sensing of flame at said burner by said flame detector means with said normally closed relay contact becoming open circuited to remove power from said resistor-ignitor element while said normally open relay contact becomes closed circuited to maintain said pilot valve energized through said impedance means, and to also energize said main valve.

7 more elements

Dependencies are inferred from the claim text.

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Abstract

An interrupted power hot wire gas ignition control system adapted to control a burner having gas valve means incorporating a pilot valve and a main valve, including:

a negative temperature coefficient resistor-ignitor element which when energized from a potential changes in resistance value as the resistor-ignitor element heats to an ignition temperature with said element mounted at said burner;
a series ignition circuit including a normally closed relay contact, a resistor, and said resistor-ignitor element with said ignition circuit adapted to be connected to a source of potential upon operation of said burner;
switch means connected to energize said pilot valve;
switch control circuit means connected to said resistor to control said switch means, and wherein said switch means is nonconductive when said resistor-ignition element is cold, and further wherein said switch means is conductive to energize said pilot valve when said resistor-ignition element is at a gas ignition temperature;
flame detector means mounted at said burner to detect the presence of a flame when said pilot valve has opened with said resistor-ignitor element at said gas ignition temperature;
flame responsive circuit means having an input connected to said flame detector means, and said flame responsive circuit means having switched output means;
said switched output means including a relay having a normally open relay contact, and further including said normally closed relay contact;
said normally open relay contact connected to said main valve to allow said normally open relay contact when closed to energize said main valve;
and impedance means including a diode connecting said pilot valve to said normally open relay contact;
said relay being energized upon the sensing of flame at said burner by said flame detector means with said normally closed relay contact becoming open circuited to remove power from said resistor-ignitor element while said normally open relay contact becomes closed circuited to maintain said pilot valve energized through said impedance means, and to also energize said main valve.

7 more elements