Fuel delivery control system

A system for controlling delivery of fuel from a fuel source to a compression-ignition engine having at least one cylinder provided with a respective fuel injector, said engine having a predetermined characteristic ignition delay time and said fuel injector being biased to a normally-closed position, comprising:

• positive-displacement pump means for receiving fuel from said source and providing intermittent, pressurized pulses of fuel flow;
• first conduit means of a preselected length extending from said pump means to a node, said fuel injector being operatively connected to said first conduit means at said node;
• bypass control valve means responsive to an electrical control signal for moving rapidly between open and closed positions, said valve means having a first port operatively connected to said first conduit means at said node and having a second port connected to a region of relatively low pressure, said control valve being normally open to permit the pulsed fuel to flow from said pump means to said low pressure region thereby bypassing said injector;
• closure of said control valve diverting said pulsed flow to said injector to cause a rapid pressure rise at the injector to a first level sufficient to initiate a pilot injection, said control valve closure creating a pressure wave in said first conduit means traveling from said node toward said pump means, said pressure wave being reflected at said pump means back to said node to effect a consequent rapid pressure increase at said injector to a second level greater than said first level and thereby effecting the main fuel injection;
• said first conduit means having a length preselected so as to return said pressure wave to said injector at a predtermined time following the initiation of pilot injection to provide a hydraulic delay between initiation of pilot injection and main injection, said hydraulic delay being substantially equal to the engine ignition delay time.