Cummins Engine Company, Inc.

Chung Y Liu

Lester L Peters

Benjamin M Yen

Julius P Perr

Edward D Smith

John D Lane

Mark S Cavanagh

Amarjit S Ghuman

Russ P Durrett

Dennis M Ashwill

Chris Sorg

Donald N Case

Fuel injection rate shaping is integrated into the pressure intensification stage of a hydraulically actuated fuel injector having a pressure intensifier. In a first embodiment, the pressure intensification plunger is formed of two parts creating a damping chamber therebetween from which fluid is forced out through orifices in a lower one of the plunger parts during an initial phase of displacement of the upper part. Thus, injection will be performed initially at a lower pressure and rate, which increases once the plunger parts make contact. In a second embodiment, a throttled flow is set via a restrictor housing that telescopingly receives the upper plunger part, so that a lower injection rate occurs while fluid is bled off through a restricted flow path between the restrictor housing and the upper plunger part, and a higher injection rate is produced once a port in the upper plunger clears the restrictor housing. In a third embodiment, the two plunger parts of the intensifier have different areas relative to each other. In a fourth embodiment, flow to the intensifier plunger is varied by the intensifier plunger co-acting with a shaped inlet port increasing the effective area of the inlet port through which flow enters the intensifier as the intensifier plunger is displaced during its injection stroke. In a fifth embodiment, a throttling effect produced by a clearance between a protrusion on the intensifier plunger and a receiving bore in the intensifier body is used reduce the intensification effect during the initial phase of injection.

Hydraulically actuated fuel injector with injection rate shaping

A fuel injection rate shaping control system is provided which effectively controls the flow rate of fuel injected into the combustion chamber of an engine to improve combustion and reduce emissions by controlling the rate of pressure increase during injection. The injection rate shaping control system includes a rate shaping control device including a rate shaping transfer passage having a predetermined length and diameter specifically designed to create a desired injection pressure rate shape. In other embodiments of the present invention, two or more rate shaping transfer passages capable of producing distinct rate shapes are packaged in various fuel injection systems to selectively provide various rate shapes depending on operating conditions. Switching valves, i.e., solenoid operated three-way valves, may be used to direct the fuel or timing fluid flow to any one of the rate shaping transfer passages. Also, a dampening means in the form of a reverse flow restrictor valve is positioned in the rate shaping transfer passage to dampen reflected pressure waves thereby minimizing the adverse effects thereof.

Fuel injection rate shaping control system

A solenoid valve for use in a fuel system includes a valve body with a central core and three interconnected passageways. A spool is disposed within the central core and by means of enlarged and reduced diameter portions controls the flow through the solenoid valve. Solenoid armatures cooperatively control movement of the valve spool which is sized and shaped so as to provide a fuel flow path from an inlet passageway to an outlet passageway when the solenoid valve is in an opened condition. When the spool is shifted to a closed condition, incoming fuel is blocked and a flow path is created from the output passageway to a drain passageway, The drain passageway allows excess fuel in the injector to drain to relieve fuel pressure on the metering plunger. As the spool moves from a closed condition to an opened condition, some fuel flows to the drain passageway. The amount of fuel 'loss' depends on the speed of the spool and the size of the drain passageway. In order to avoid the higher cost associated with drilling a small diameter hole through the valve body, a larger drilled hole is used. The enlarged end of the valve spool is extended so as to block a substantial portion of the drain passageway orifice. The blocked orifice yields a smaller flow through area and this reduced flow orifice area reduces transition loss and cavitation.

Three-way flow valve with variable drain orifice area

Growing community of inventors

Columbus, IN, United States of America

Chung Y Liu