Solenoid operated pump-line-nozzle fuel injection system and inline pump therefor

摘要

A pump-line-nozzle fuel injection system in which a low pressure supply pump is coupled to a high pressure in-line pump having a plurality of pumping cylinders, each of which has a cam-driven timing plunger and a floating metering plunger. During the retraction stroke, flow to a timing chamber formed between the pistons is controlled by a first solenoid valve while the fuel flow into a metering chamber is controlled by a second solenoid valve. During metering, the discharge side of the pump is closed relative to a high pressure delivery line by a delivery valve. During the compression stroke, return flow is precluded by check valves in the supply lines to the timing and metering cylinders. Most importantly, since only one pumping cylinder of each pumping group undergoes its metering and injection phases at a given time, the timing and metering plungers of the other pumping cylinders being held in their maximally inwardly displaced, end-of-injection positions at that time, a single set of timing and metering solenoid valves can be used to individually meter fuel into the metering chamber and timing fluid into the timing chamber, independently and with the quantities metered being infinitely adjustable on a individual cylinder and cycle-to-cycle basis. Once the fuel is sufficiently pressurized, the delivery valve opens and the fuel is delivered to the respective injector via the high pressure delivery line from the particular one of the pumping cylinders.