Control system

Abstract

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.

Dependencies are inferred from the claim text.