Fuel injector with feedback control

A fuel injector for injecting fuel at high pressure into the combustion chamber of an engine, comprising:

• an injector body containing an injector cavity and an injector orifice communicating with one end of said injector cavity to discharge fuel into the combustion chamber;
• a nozzle valve element positioned in one end of said injector cavity adjacent said injector orifice, said nozzle valve element movable between an open position in which fuel may flow through said injector orifice into the combustion chamber and a closed position in which fuel flow through said injector orifice is blocked;
• a control volume positioned to receive a pressurized supply of fuel;
• a drain circuit for draining fuel from said control volume to a low pressure drain, said drain circuit including a drain orifice for restricting drain flow;
• a valve seat positioned along said drain circuit;
• an injection control valve positioned along said drain circuit to control fuel flow from said control volume, said injection control valve including a reciprocally mounted control valve member movable between an open position permitting flow through said drain circuit and a closed position in sealing abutment against said valve seat to block flow through said drain circuit, said control valve member including an elongated portion extending from a position adjacent said valve seat toward an upstream portion of said drain circuit, said elongated portion of said control valve member including a first section for engaging said valve seat and a second section formed separately from, and positioned in abutment with, said first section, said second section containing said drain orifice;
• and
• a guide surface formed on said injector body and positioned adjacent said elongated portion of said control valve member to permit relative sliding movement of said elongated portion while guiding said elongated portion.