Needle controlled fuel injector with two control valves

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 first control volume positioned to receive a pressurized supply of fuel;
• a drain circuit for draining fuel from said first control volume to a low pressure drain;
• a first valve seat positioned along said drain circuit;
• a first injection control valve positioned along said drain circuit to control fuel flow from said first control volume, said first 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 first valve seat to block flow through said drain circuit;
• a second control volume positioned adjacent an outer end of said nozzle valve element to receive a pressurized supply of fuel, said drain circuit positioned to drain fuel from said second control volume to the low pressure drain;
• a second valve seat positioned along said drain circuit;
• a second injection control valve positioned along said drain circuit to control fuel flow from said second control volume, said second injection control valve including a reciprocally mounted control valve member movable between an open position permitting flow through said drain circuit to cause a decrease in fuel pressure in said second control volume and movement of said nozzle valve element into said open position, and a closed position in sealing abutment against said second valve seat to block flow through said drain circuit to cause an increase in fuel pressure in said second control volume and movement of said nozzle valve element into said closed position, wherein movement of said first injection control valve into said open position causes a decrease in fuel pressure in said first control volume causing movement of said second injection control valve into said open position.