Hydraulically-actuated fuel injector with direct control needle valve

摘要

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. A second valve member is disposed in the injector body and is moveable in response to the actuator, while the actuation inlet is open to the actuation fluid cavity, between an off position in which the needle control chamber is open to a source of high pressure fluid and an on position in which the needle control chamber is open to a low pressure passage. A fuel injection system including a plurality of such hydraulically actuated fuel injectors is also disclosed.