General Electric Company

Jaykishan C Patel

Alvin D Wyland

A control system for a fuel flow control valve which is enabled on thermostatic demand and closed thereafter if ignition fails. The control system includes an enabling circuit for the control valve in series with a controlled switching device and a circuit for energizing a fuel igniting system. The control system also includes circuitry for selectively supplying enabling pulses to the controlled switching device to enable the control valve and to energize the fuel igniting system along with timing circuitry for selectively preventing the application of those enabling pulses to the controlled switching device. The timing circuitry includes a transistor which when enabled shunts those pulses to ground rather than to the controlled switching device, and the control system is fail safe in the sense that neither a shorted transistor nor a shorted controlled switching device will allow the escape of significant unburned fuel.

Control system

A low voltage thermostatically energizable control system for a fuel burner having a fuel valve and operable from a direct current. The control system includes means for actuating the fuel valve to enable flow of a combustible fuel from the burner and means for spark igniting the fuel emitted from the burner. Means for detecting a flame is disposed near the burner, and the impedance between the detecting means and a point of reference potential is greater when no flame is present at the burner and is lower when a flame is present at the burner. A semiconductor device is coupled to the detecting means for conducting current only when the impedance between the detecting means and the point of reference potential is lower thereby to indicate the presence of a flame, and means is responsive to the current conducted by the semiconductor device for disabling the spark igniting means.

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Clinton, IA, United States of America

Jaykishan C Patel