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US 4,382,770 AGranted
Safe start fuel burner control system
AssigneeHoneywell Inc.
InventorB. Hubert Pinckaers
Life of this patent
Estimating the term…
Abstract
An intermittent gas pilot system utilizing a flame signal simulating circuit means provides for both dynamic as well as static safe start checking for the system. A simulated flame signal is provided so that the relays contained within the system must be checked dynamically before the system will allow the opening of the main gas valve.
Claims6
A fuel burner control system for a gas fuel burner having pilot gas source means, main burner gas source means, ignition means for the pilot gas source means, and power switch means adapted to initiate operation of said control system from a voltage source, including:
- flame detector means and flame detection circuit means having a voltage output in response to the presence of a flame at said flame detector means;
- solid state switching means having an input responsive to said flame detection circuit means, and having an output connected to control first relay means;
- said relay means having normally open contacts and normally closed contacts;
- flame signal simulating circuit means responsive to the application of said voltage source to said system upon said power switch closing to provide a brief false flame signal voltage to said solid state switching means to simulate a flame at said flame detector means thereby energizing said first relay means;
- second relay means having normally open contacts and normally closed contacts;
- relay conditioning circuit means responsive to the application of said voltage source upon the closing of said power switch means to condition said second relay means to immediately operate after said first relay means completes an operating cycle responsive to said false flame signal voltage;
- said relay conditioning circuit means including thermal time delay means having a negative temperature coefficient resistance in series with said second relay means;
- a heater for said negative temperature coefficient resistance energized upon the closing of said power switch means;
- and relay contact interconnection means connecting said relay contacts to said ignition means, said pilot gas source means, and said main burner gas source means to safely operate said fuel burner;
- said safe operation requiring that said false flame signal voltage cause said solid state switch means to condition said second relay means to operate after said false signal is removed and a further flame signal is received.
7 more elements
Dependencies are inferred from the claim text.