Abstract: A fuel injector that includes a flying armature movable relative to a pintle stop, and an electromagnetic circuit configured to move the flying armature away from the pintle stop prior to accelerating the armature toward the pintle stop as part of moving the pintle to open the fuel injector. The flying armature increases the total force applied to the pintle to open the fuel injector by supplementing the static force imparted to the armature by a magnetic field with an impact force imparted by the armature being in motion toward and impacting with the pintle stop. The arrangement of magnetic circuit devices and materials used to make the magnetic circuit devices cooperate to provide a reversing force that urges the armature away from before urging the armature toward the pintle stop, and increases the rate at which the force that urges the armature toward the pintle stop increases.

Abstract: A fuel injector that includes a sliding armature, decoupled armature, or flying armature movable between a pintle stop and a housing stop. Flying armatures are generally used to increase the total force applied to the pintle stop for lifting the pintle off a nozzle seat to open the fuel injector. When the fuel injector is turned off, a housing stop is arranged to absorb kinetic energy present in the flying armature so that the kinetic energy is not imparted to the nozzle seat.

Abstract: A fuel injector that includes a sliding armature, decoupled armature, or flying armature movable between a pintle stop and a housing stop. Flying armatures are generally used to increase the total force applied to the pintle stop for lifting the pintle off a nozzle seat to open the fuel injector. When the fuel injector is turned off, a housing stop is arranged to absorb kinetic energy present in the flying armature so that the kinetic energy is not imparted to the nozzle seat.

Abstract: A fuel injector that includes a flying armature movable relative to a pintle stop, and an electromagnetic circuit configured to move the flying armature away from the pintle stop prior to accelerating the armature toward the pintle stop as part of moving the pintle to open the fuel injector. The flying armature increases the total force applied to the pintle to open the fuel injector by supplementing the static force imparted to the armature by a magnetic field with an impact force imparted by the armature being in motion toward and impacting with the pintle stop. The arrangement of magnetic circuit devices and materials used to make the magnetic circuit devices cooperate to provide a reversing force that urges the armature away from before urging the armature toward the pintle stop, and increases the rate at which the force that urges the armature toward the pintle stop increases.

Abstract: A shape memory alloy actuator assembly for a fuel injector, having a small package integral design, wherein the response times of the shape memory alloy element is decreased to less than about 1 millisecond by forced, convective heat transfer from the SMA element or elements. The forced, convective heat transfer is provided by the circulation of fluid across the SMA element by a metering orifice plate, which directs a fluid flow across the SMA element so as to maximize the area of contact between the fuel and the SMA element, regardless of whether the fuel injection valve is opened or closed. Use of forced convective heat transfer in accordance with the present invention allows greater power input levels than previously possible without resulting in an over-temperature condition of the SMA alloy, as well as constant response times.

Abstract: A direct injection fuel injector and method of operation wherein high fuel pressure exerting an opening force on an injection valve is slightly overbalanced by a return spring tending to close the valve. A first solenoid acts to open the valve against the excess return spring force and a second solenoid acts to close the valve when the first solenoid is de-energized. Rapid valve closing is provided by energizing the second solenoid before de-energizing the first solenoid, the force of the second solenoid when the valve is open being insufficient to overcome the force of the first solenoid holding the valve open. Thus, the second solenoid magnetic force is fully developed and quickly closes the injection valve when the first solenoid is de-energized. Various additional features are disclosed.

Abstract: A direct injection fuel injector and method of operation wherein high fuel pressure exerting an opening force on an injection valve is slightly overbalanced by a return spring tending to close the valve. A first solenoid acts to open the valve against the excess return spring force and a second solenoid acts to close the valve when the first solenoid is de-energized. Rapid valve closing is provided by energizing the second solenoid before de-energizing the first solenoid, the force of the second solenoid when the valve is open being insufficient to overcome the force of the first solenoid holding the valve open. Thus, the second solenoid magnetic force is fully developed and quickly closes the injection valve when the first solenoid is de-energized. Various additional features are disclosed.

Abstract: An improved method and apparatus for opening and closing a high performance shape memory alloy (SMA) fuel injector that minimizes performance variations due to changes in ambient temperature. When opening the injector to commence fuel injection, a relatively high voltage is applied to an SMA element of the injector to quickly heat the element to its high temperature state, quickly opening the valve. The current level is monitored as a measure of the element resistivity, and when the determined resistivity indicates that the high temperature state transition is complete, the voltage is reduced to a hold value, sufficient to continue resistivity measurement. When the determined resistivity indicates that the element is beginning to transition back to the ambient temperature state, the high voltage is re-applied to begin a new control cycle. To close the injector, the electric heating is discontinued, and fuel circulating through the injector cools the element to its ambient temperature state.

Abstract: A shape memory alloy actuator assembly for a fuel injector, wherein the response times of the shape memory alloy element is decreased to less than about 1 millisecond by forced, convective heat transfer from the SMA element or elements. The forced, convective heat transfer is provided by the circulation of fluid across the SMA element by a metering orifice plate, which directs a fluid flow across the SMA element so as to maximize the area of contact between the fuel and the SMA element, regardless of whether the fuel injection valve is opened or closed. Use of forced convective heat transfer in accordance with the present invention allows greater power input levels than previously possible without resulting in an over-temperature condition of the SMA alloy, as well as constant response times.

Abstract: A fuel system including a fuel nozzle is disclosed. The fuel nozzle is adapted to receive pulsed pressurized fuel from a source and includes a valve seat assembly having a valve seat body with a longitudinally extending passage. The passage of the valve seat body has a valve seat extending thereabout and interfaces with a downstream opening valve element which is disposed within the longitudinally extending passage and operates to move into and out of sealing engagement with the valve seat to regulate the flow of pressurized fuel though the passage. The valve element has a spherically configured upstream surface for sealing engagement with the valve seat which includes an annular drag groove extending thereabout. The drag groove functions to increase viscous drag force, in the downstream opening direction, which is imparted on the valve element by fuel flow over the spherical upstream surface. The nozzle also has an annular, fuel directing orifice disc which is disposed downstream of the valve seat.

Abstract: A fuel injection system is disclosed having a fuel injection nozzle which receives pressurized fuel pulses from a source. The nozzle includes a body having a tubular nozzle body with a longitudinally extending opening extending therethrough. A valve seat is located between the upstream and downstream ends of the longitudinal opening in the valve body for engagement with a valve member to thereby regulate the flow of fuel through the opening. A downstream stop member includes a hollow cylinder with a diametrical member extending across one end. The cylindrical stop member is received over the downstream end of the nozzle body with the diametrically extending member disposed across the downstream end of the longitudinal opening to thereby limit the outward range of movement of the valve member from the opening. As a result, the valve member and the downstream end of the longitudinally extending opening define an annular fuel metering orifice therebetween to regulate the flow of fuel from the nozzle.

Abstract: A fuel injection system is disclosed having a fuel injection nozzle which receives pressurized fuel pulses from a source. The nozzle includes a body having a tubular nozzle body with a longitudinally extending opening extending therethrough. A valve seat is located between the upstream and downstream ends of the longitudinal opening in the valve body for engagement with a valve member to thereby regulate the flow of fuel through the opening. A downstream stop member includes a hollow cylinder with a diametrical member extending across one end. The cylindrical stop member is received over the downstream end of the nozzle body with the diametrically extending member disposed across the downstream end of the longitudinal opening to thereby limit the outward range of movement of the valve member from the opening. As a result, the valve member and the downstream end of the longitudinally extending opening define an annular fuel metering orifice therebetween to regulate the flow of fuel from the nozzle.