Cummins Engine Company, Inc.

J P Perr

Lester L Peters

A S Ghuman

Dennis M Ashwill

B M Yen

L D Tikk

L L Peters

Y J Tarr

An injection rate shaping nozzle assembly for a fuel injector is provided which includes a closed nozzle valve element and a rate shaping control device including an injection spill circuit for spilling a portion of the fuel to be injected to produce a predetermined time varying change in the flow rate of fuel injected into a combustion chamber. The spill circuit includes a spill passage integrally formed in the nozzle valve element. The rate shaping control may include a spill valve for controlling the spill flow through the spill circuit to create a low injection flow rate followed by a high injection flow rate. The spill passage may communicate with the injector nozzle cavity between injection events or alternatively may be blocked to prevent spill flow between injection events. The rate shaping control device may include a spill accelerating device in the form of a spill chamber formed in the nozzle valve element for creating a rapid increase in the spill flow rate. In another embodiment, the rate shaping device may include a throttling passage integrally formed in the nozzle valve element to vary the rate at which fuel pressure in the nozzle cavity increases so as to vary the flow rate through the injector orifices.

Injection rate shaping nozzle assembly for a fuel injector

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.

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

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Columbus, IN, United States of America

J P Perr