Abstract: A hydraulically actuated fuel injector has an injector body including a barrel and defining a nozzle chamber, a needle control chamber, and a nozzle outlet that opens to the nozzle chamber. The injector body further includes an actuation fluid inlet and an actuation fluid drain. A barrel defines an actuation fluid cavity and a piston bore, which includes an upper bore and a lower bore. Fuel is hydraulically pressurized in the nozzle chamber. A piston with a stepped top slides in the piston bore and moves in between a retracted position and an advanced position. A needle valve member in the nozzle chamber moves between an open position and a closed position. The needle valve member includes a closing hydraulic surface exposed to pressure in the needle control chamber.

Abstract: A hydraulically actuated fuel injector has an injector body including a barrel and defining a nozzle chamber, a needle control chamber, and a nozzle outlet that opens to the nozzle chamber. The injector body further includes an actuation fluid inlet and an actuation fluid drain. A barrel defines an actuation fluid cavity and a piston bore, which includes an upper bore and a lower bore. Fuel is hydraulically pressurized in the nozzle chamber. A piston with a stepped top slides in the piston bore and moves in between a retracted position and an advanced position. A needle valve member in the nozzle chamber moves between an open position and a closed position. The needle valve member includes a closing hydraulic surface exposed to pressure in the needle control chamber.

Abstract: A hydraulically actuated fuel injector has an injector body including a barrel and defining a nozzle chamber, a needle control chamber, and a nozzle outlet that opens to the nozzle chamber. The injector body further includes an actuation fluid inlet and an actuation fluid drain. A barrel defines an actuation fluid cavity and a piston bore, which includes an upper bore and a lower bore. Fuel is hydraulically pressurized in the nozzle chamber. A piston with a stepped top slides in the piston bore and moves in between a retracted position and an advanced position. A needle valve member in the nozzle chamber moves between an open position and a closed position. The needle valve member includes a closing hydraulic surface exposed to pressure in the needle control chamber.

Abstract: A hydraulically actuated fuel injector is disclosed having an injector body defining an actuation fluid inlet, an actuation fluid cavity, a nozzle outlet, and a needle control chamber. An actuator is attached to the injector body and a first valve member is disposed in the injector body and is moveable in response to the actuator between a first position in which the actuation fluid inlet is open to the actuation fluid cavity and a second position in which the actuation fluid inlet is closed to the actuation fluid cavity. A needle valve member is disposed in the injector body and is moveable between an open position in which the nozzle outlet is open and a closed position in which the nozzle outlet is blocked. The needle valve member has a closing hydraulic surface exposed to pressure in the needle control chamber.

Abstract: A fuel injection system includes a plurality of hydraulically actuated fuel injectors with direct control needle valves. Each injector has an injector body that defines an actuation fluid inlet, a fuel supply passage and a needle control chamber. A needle valve member is movably mounted in the injector body and has a closing hydraulic surface exposed to pressure in the needle control chamber. Each injector also includes a relatively slow moving actuation fluid control valve member and a relatively fast moving needle control valve member. A source of low pressure fluid is connected to the fuel supply passage, and a source of high pressure fluid is connected to the actuation fluid inlet.

Abstract: A hydraulically actuated fuel injector includes an injector body having a nozzle chamber that opens to a nozzle outlet. A control valve is mounted in the injector body and is attached to a solenoid that is moveable between a rest position and a fully energized position. A piston/plunger/barrel assembly is utilized to hydraulically pressurize fuel in the nozzle chamber to a fuel pressure that is substantially proportional to an amount of current being supplied to the solenoid. A needle valve member is positioned in the nozzle chamber and moveable between an open position in which the nozzle outlet is opened and a closed position in which the nozzle outlet is blocked. Finally, a spring is utilized to bias the solenoid toward its rest position.

Abstract: A hydraulically-actuated piston and barrel assembly includes a barrel defining an actuation fluid cavity and a piston bore, which includes an upper bore and a lower bore. A stepped piston is slidably received in the piston bore and moveable between a retracted position and an advanced position. The stepped top of the piston includes a first area that is separate from a second area. The first area and the upper bore define an upper cavity connected to the actuation fluid cavity through a relatively unrestricted flow area, when the piston is in its retracted position. The second area and the lower bore define a lower cavity connected to the actuation fluid cavity through a relatively restricted flow area when the piston is in its retracted position. The first area is exposed to fluid pressure in the upper cavity and the second area is exposed to fluid pressure in the lower cavity over a portion of the piston's movement from its retracted position toward its advanced position.

Abstract: A hydraulically actuated fuel injector includes an injector body having an actuation fluid inlet and a needle control chamber. A hydraulic means within the injector pressurizes fuel in the injector body. The hydraulic means includes an actuation fluid control valve having a solenoid and is movable to open and close the actuation fluid inlet. A needle valve member includes a closing hydraulic surface exposed to pressure in the needle control chamber. A needle control valve, which utilizes the same solenoid, is mounted in the injector body and movable to open and close the needle control chamber to a source of high pressure fluid. The slower response time of the actuation fluid control valve allows for direct control of the fast responding needle valve by a single fast acting solenoid.

Abstract: A hydraulically actuated fuel injector includes an injector body having an actuation fluid inlet, an actuation fluid cavity, a nozzle chamber open to a nozzle outlet and a needle control chamber. A hydraulic means within the injector pressurizes fuel in the nozzle chamber. The hydraulic means includes an actuation fluid control valve having a solenoid and is moveable between a first position in which the actuation fluid inlet is open to the actuation fluid cavity and a second position in which the actuation fluid inlet is closed to the actuation fluid cavity. A needle valve member is positioned to reciprocate in the nozzle chamber between an open position in which the nozzle outlet is open and a closed position in which the nozzle outlet is closed. The needle valve member includes a closing hydraulic surface exposed to pressure in the needle control chamber.

Abstract: A hydraulically-actuated fuel injector includes an injector body having a nozzle chamber, a nozzle outlet, an actuation fluid inlet, an actuation fluid drain, an actuation fluid cavity and a pressure relief passage extending between the actuation fluid cavity and the actuation fluid drain. A hydraulic means, including an actuation fluid control valve mounted within the injector body, is used for pressurizing fuel in the nozzle chamber. A needle valve member is mounted to reciprocate in the nozzle chamber between an open position in which the nozzle outlet is open and a closed position in which the nozzle outlet is closed. A relief valve is mounted within the injector body and has a first position in which the pressure relief passage is closed and a second position in which the pressure relief passage is open.