Gm Global Technolgoy Operations, Inc.

A-I-L Corporation

United Technologies Diesel Systems, Inc.

Thomas J Wich

A system for controlling delivery of fuel to a compression ignition engine having a predetermined characteristic ignition delay. A positive-displacement pump, typically a high-pressure, multiplunger in-line pump, receives fuel from a source and provides intermittent, pressurized pulses of fuel flow. A conduit extends from a pumping chamber to a node to which a normally-closed fuel injector is operatively connected. A normally-open, solenoid-controlled bypass valve has an inlet port connected to the conduit node for allowing fuel to bypass the injector. When a signal is applied to the bypass valve it rapidly closes, causing the pressure at the injector to rapidly increase to a first injector-opening level to inject pilot fuel. Thereafter, following a predetermined hydraulic delay, the pressure at the injector rapidly increases to a second level greater than the first to provide main fuel injection. The conduit length determines the hydraulic delay and is selected to have a predetermined time relation with the engine's ignition delay time. The hydraulic delay substantially corresponds with the ignition delay time in the preferred embodiment. The bypass valve also responds rapidly in the closing direction. Part of the make-up fuel delivered by the pump is provided by reverse flow of fuel through the open bypass valve.

Fuel delivery control system

A normally-open, solenoid-controlled valve rapidly controls the flow of liquid between a high pressure supply and a relatively lower pressure drain. The valve includes a stationary valve-seat spindle and a cylindrical valve sleeve encircling and slidable along part of the valve-seat spindle. The valve-seat spindle is provided with an annular control edge and the valve sleeve includes a frustoconical pressure-responsive contact surface which is moved into and out of valve-closing contact with the control edge by means of axial reciprocation of the valve sleeve between valve-closed and valve-open positions. The valve-seat spindle includes a flow passage therein which is in continuous fluid communication with a high pressure fluid inlet in a valve housing and which extends to and discharges into a plenum region formed between the spindle and the sleeve adjacent to the control edge and relatively toward that part of the seat spindle along which the valve sleeve slides. When energization of the solenoid is discontinued, the high pressure liquid in the plenum acts axially on the valve sleeve, and particularly the pressure-responsive contact surface, to rapidly open the valve. The response rate and simplicity of the valve are enhanced by the absence of a biasing spring. The valve is suited for use as a bypass valve in integral combination with a high pressure fuel injector nozzle of the pressure-responsive type.

Solenoid valve, particularly as bypass valve with fuel injector

An electromagnetic unit fuel injector for use in a diesel engine includes a housing having a bushing with an externally actuated plunger reciprocable therein to define a pump chamber open at one end for the discharge of fuel to a spring biased, pressure actuated fuel injection nozzle. The pump chamber is connected to a supply and spill chamber means via flow-through solenoid actuated, normally open, hollow pressure sensitive valve to permit the ingress and egress of fuel. The supply and spill chamber means adjacent to the head of the valve is in flow communication with a pressure equalization and spring chamber means at the opposite end of the valve via a passage through the valve and these chambers are in direct flow communication with a source of fuel at a relatively low supply pressure. During a pump stroke of the plunger, the solenoid can be energized, as desired, to push the pressure sensitive valve to a closed position relative to an associate valve seat so as to block flow from the pump chamber to the supply and spill chamber means thus allowing the plunger to effect pressurization of the fuel so as to effect discharge of fuel from the injection nozzle.

Electromagnetic unit fuel injector

An electromagnetic unit fuel injector includes a pump assembly having an externally actuated plunger reciprocable in a bushing means to define a variable volume pump chamber and a pressure actuated fuel injection nozzle. Fuel, at a suitable supply pressure, in a supply chamber is adapted to be in flow communication with the pump chamber by suitable passage means having a normally open, electromagnetic valve means controlling flow through a first portion thereof and a normally open servo control valve means, including a servo control valve and piston, controlling flow through a second portion thereof. Fuel injection during a pump stroke of the plunger is initiated by the controlled energization of the electromagnetic valve means to block return flow of fuel so as to effect closure of the servo control valve means whereby the fuel pressure can be further intensified to effect operation of the injection nozzle.

A hydraulic control mechanism for controlling timing and output as a function of speed and throttle position on a diesel engine fuel injection pump. The hydraulic control mechanism includes two valves and three flow orifices arranged to control governing fluid pressure supplied to the pump so as to provide idle governing and overspeed governing as well as load control in between of the pump.

Growing community of inventors

Springfield, MA, United States of America

Thomas J Wich