Electronic control system for a fuel pump

摘要

An electronic control system for a fuel pump of an internal combustion engine includes a power circuit which controls the flow of electric current in an electromagnetic device coupled to a spill valve of the fuel pump. Power is supplied to the power circuit through a resistor through which power is also supplied to an engine speed sensing circuit. The system also includes a control unit which supplies control signals to the power circuit to effect closure of the valve and hence delivery of fuel, in timed relationship with the engine. The control unit receives the speed signal from the speed sensing circuit and also senses the voltage applied thereto. In addition it receives a demand signal from a transducer and controls current flow in a relay winding having contacts in parallel with the resistor. In normal operation the contacts are closed but in a fault situation with the demand low and the speed high the winding is de-energized and the voltage applied to the power circuit and speed sensing circuit falls below a standby level which is sensed by the control unit to maintain the winding energized.