Fuel injection systems

Claim 1

A fuel injection system for an internal combustion engine which includes a plurality of electromagnetically operated fuel injection valves, at least one pulse generator circuit producing electrical pulses for energizing said valves, so that each valve is opened for a period depending on the duration of the pulse by which it is energized, to pass fuel to the engine, said pulse generator circuit including a timing circuit for controlling the duration of said pulses, means to feed at least one variable electrical potential, which varies as a function of at least one parameter of engine operation, to the pulse generator circuit to control said pulse duration, trigger means to initiate said pulses, said trigger means operating at a frequency depending on the rotational speed of the engine, and further pulse-initiating means operable independently of said trigger means to initiate further pulses when acceleration of the engine is required, said further pulses being applied to the fuel injection valves in addition to those pulses initiated by said triggEr means, whereby additional fuel is delivered through said fuel-injection valves to enhance acceleration, said further pulse initiating means including a plurality of auxiliary pulse generator circuits for producing a plurality of successive further pulses each of which simultaneously energizes all the valves, the number of said generator circuits corresponding to the maximum number of said successive further pulses, the system including a manifold absolute pressure transducer which produces an output varying in dependence upon changes in pressure in the induction manifold, the output being fed simultaneously to said auxiliary pulse generator circuits, the auxiliary pulse generator circuits being arranged to be triggered by different levels of said output relative to a quiescent level determined by the value of said output corresponding to the manifold pressure before the engine is conditioned to accelerate, said system further including a pair of main pulse generator circuits, each including an output amplifier connected to a group of fuel injection valves, the auxiliary pulse generator circuits being connected in parallel between said transducer and both of said output amplifiers.