Patent ID: 8082902

Claim:
A fuel injector comprising: an injector body including a high pressure inlet, a low pressure drain and a nozzle outlet, and including a nozzle supply passage, a needle control chamber and a shoulder control chamber disposed therein; a first electrical actuator, which includes a piezo stack, positioned in the injector body; a second electrical actuator, which includes a piezo stack, positioned in the injector body; an intensifier piston slidably positioned in the injector body with a shoulder surface that is exposed to fluid pressure in the shoulder control chamber and located between a large surface and a small surface; a needle valve member with an opening hydraulic surface exposed to fluid pressure in the nozzle supply passage, and a closing hydraulic surface exposed to fluid pressure in the needle control chamber; a direct control valve member coupled to the first electrical actuator and being movable between a first position at which the needle control chamber is fluidly connected to the low pressure drain, and a second position at which the needle control chamber is fluidly blocked to the low pressure drain; an intensifier control valve coupled to the second electrical actuator and movable between a first position at which the shoulder control chamber is fluidly connected to the low pressure drain, and a second position at which the shoulder control chamber is fluidly blocked to the low pressure drain; and an injector reset valve member movable between a first position at which the shoulder control chamber is fluidly connected to the common rail, and a second position at which the shoulder control chamber is fluidly blocked to the common rail.