Hydraulically actuated fuel injector with proportional control

A hydraulically actuated fuel injection system comprising:

• a source of high pressure actuation fluid;
• a low pressure actuation fluid reservoir;
• a source of fuel fluid different from said actuation fluid;
• a hydraulically actuated fuel injector comprising:
• an injector body that defines a fuel supply passage, an actuation fluid inlet, an actuation fluid drain and a nozzle chamber that opens to a nozzle outlet;
• a solenoid actuated control valve attached to said injector body;
• hydraulic means, within said injector body, for pressurizing fuel in said nozzle chamber to a fuel pressure that is substantially proportional to an amount of current being supplied to said solenoid actuated control valve;
• a needle valve member positioned in said nozzle chamber and moveable between an open position in which said nozzle outlet is open and a closed position in which said nozzle outlet is blocked;
• and
• a first supply passage connecting said actuation fluid inlet to said source of high pressure actuation fluid;
• a second supply passage connecting said fuel supply passage to said source of fuel fluid different from said actuation fluid;
• a drain passage connecting said actuation fluid drain to said low pressure actuation fluid reservoir;
• and
• a computer in communication with and capable of controlling said solenoid.

A hydraulically actuated fuel injection system comprising:

• an injector body having an actuation fluid cavity that opens to an actuation fluid inlet, a first actuation fluid drain and a piston bore, and having a plunger bore that opens to a fuel supply passage and a nozzle chamber, and said nozzle chamber opens to a nozzle outlet;
• a control valve mounted in said injector body and being movable between a first position that fully opens said actuation fluid inlet and closes said actuation fluid drain, and a second position that closes said actuation fluid inlet and opens said actuation fluid drain;
• a solenoid attached to said control valve;
• a piston positioned to reciprocate in said piston bore between an upper position and a lower position;
• a plunger positioned to reciprocate in said plunger bore between an advanced position and a retracted position;
• a portion of said plunger bore and said plunger defining a fuel pressurization chamber that opens to said nozzle chamber;
• a needle valve member positioned to reciprocate in said nozzle chamber between a closed position that blocks said nozzle outlet and an open position that opens said nozzle outlet;
• means, within said injector body, for biasing said needle valve member toward said closed position;
• and
• means for positioning said control valve at a partially open position between said first position and said second position in which said actuation fluid drain is closed and said actuation fluid inlet is less than fully open to said actuation fluid cavity.