Gas ignition control

An apparatus for automatic fuel ignition consisting essentially of:

• (a) A resistance type fuel igniter which reaches a temperature above the ignition temperature of the fuel when sufficient electrical current from an electrical source passes through the igniter;
• (b) A fuel valve which opens upon application of a first predetermined electrical current from said electrical source and which will remain open but will not initially open upon the application of a second predetermined electrical current from said electrical source, said second predetermined electrical current being less than said first predetermined electrical current;
• (c) An activating switch electrically connected between said fuel valve and said electrical source and between said igniter and said electrical source so that neither said valve nor said igniter will operate unless said activating switch is closed;
• (d) A time delay latching relay having a set of electrical contacts and a first relay coil electrically connected in series between said gas valve and said activating switch, said relay contacts being normally closed to permit current to flow through the apparatus and latching open after said first predetermined current flows through the relay coil for a pre-set time which prevents current from flowing through the apparatus;
• (e) A resistance in series with said gas valve, said resistance being large enough to reduce electrical current flowing through the valve, from said first predetermined electrical current which flows through the valve when a low resistance electrical path connects said valve to said electrical source, to said second predetermined electrical current when only said resistance passes electrical current to said valve;
• (f) A second set of relay contacts activated by a second relay coil, said contacts being a single pole double throw set of electrical relay contacts, said second contacts normally connecting a low resistance electrical path in the form of a shunt around said resistance, and connecting a shunt around said first relay coil when the second relay coil is activated to complete said shunt around said first relay coil;
• (g) A third set of relay contacts also activated by said second relay coil, said third set of relay contacts normally electrically connecting said fuel igniter and said activating switch, said contacts disconnecting said igniter from said activating switch when said second relay coil is activated;
• (h) A sensor which is connected in series with said second coil to the electrical source, said sensor normally preventing flow of electrical current through said second relay coil, said sensor being able to detect a flame and upon such detection permitting electrical current to flow through said second relay coil before said trip relay operates to turn off the gas valve, said second relay coil then being activated by said electrical current to activate said second and third set of contacts thus removing the shunt from around the resistance in series with the valve, placing a shunt around the trip relay coil thus deactivating the trip relay and opening the igniter circuit thus deactivating the igniter.