Abstract: An improved fuel injector for providing precise control over injection timing, quantity and rate shape is provided which includes a fuel pressure balancing device for balancing the fuel pressure forces acting on a needle valve element while the element is in both the closed and open positions thereby permitting an actuator to more precisely and predictably control the movement of the needle valve element. The fuel pressure balancing device includes a cavity formed in the needle valve element and pressure balancing surfaces formed on the needle valve element and positioned in the cavity. The actuator may be a piezoelectric actuator for compressing actuating fluid in an actuating fluid circuit which includes a fluid chamber positioned adjacent a needle valve element and fluidically separate from a fuel supply circuit for supplying high pressure fuel for injection. Actuating fluid pressure in the chamber acts on the needle valve element to initiate injection.

Abstract: A fuel injector assembly is provided which operates to effectively creating a low injection flow rate followed by a high injection flow rate during all engine operating conditions, including idle and low engine speed conditions, to produce a high quality fuel spray with proper atomization and thus improved fuel air mixing resulting in improved emissions abatement and fuel economy. The assembly includes two biased valve elements designed to sequentially open and close to initially open a limited number of orifices followed by the opening of a remainder of the orifices thereby effectively varying the available cross sectional flow area from the nozzle cavity into the combustion chamber of the engine during the injection event. The nozzle valve elements may be spring biased or fluid pressure biased and include biasing surfaces sized to cause the sequential opening and closing of the elements.

Abstract: 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.

Abstract: 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 device may include a spill accelerating chamber in formed in the nozzle valve element for creating a rapid increase in the spill flow rate. A spill circuit purge device is provided to remove fuel from the spill circuit and accelerating chamber between each of the injection events thereby ensuring an unimpeded, effective spill fuel flow during the next spill event.

Abstract: In accordance with preferred embodiments of the invention a timing adjustment device includes a cam follower that is engaged between an overhead cam and an injector rocker arm, and is mounted on a rotatable eccentric shaft. The geometry of the eccentric shaft and cam follower is designed so that, as timing is varied by rotation of the eccentric shaft, no change is produced in the vertical height of the rocker arm when the cam shaft is on the outer base circle and the injector is bottomed, in order to assure that the "mechanical crush" of the PT type injector is constant despite changes in timing. In a first application of the timing arrangement, it is used together with a simple injector, which does not utilize a multi-plunger arrangement to form a hydraulic link, to achieve lower parasitic losses.

Abstract: 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.

Abstract: 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.