Directly actuated injection valve with a ferromagnetic needle

An injection valve for injecting fuel into a combustion chamber of an internal combustion engine, said injection valve comprising:

• (a) a valve housing comprising:
• a fuel inlet port;
• an interior chamber fluidly connected to said fuel inlet port;
• a nozzle comprising a valve seat and a nozzle orifice providing a fluid passage from said interior chamber to said combustion chamber;
• (b) a valve needle formed from a ferromagnetic material comprising a cylindrical portion having a sealing end and a piston portion having a pre-load end, said valve needle disposed within said valve housing wherein said valve needle is movable between a closed position at which said sealing end contacts said valve seat to fluidly seal said interior chamber from said nozzle orifice, and an open position at which said sealing end is spaced apart from said valve seat whereby said interior chamber is fluidly connected with said nozzle orifice, wherein valve lift equals distance traveled by said sealing end away from said valve seat;
• (c) a needle spring associated with said pre-load end of said valve needle, wherein said needle spring is compressed to apply a closing force to said valve needle for biasing said valve needle in said closed position;
• (d) an actuator assembly that may be activated to apply an opening force to said valve needle that is stronger than said closing force, for moving said valve needle to said open position, said actuator assembly comprising:
• a tubular magnetostrictive member disposed around said cylindrical portion of said valve needle;
• an electrical coil disposed around said magnetostrictive member;
• a flux tube disposed around said electrical coil;
• and
• a support for said actuator assembly that acts as a pole and provides a fixed position for one end of said magnetostrictive member relative to said valve housing;
• and
• (e) a hydraulic link assembly comprising a sealed hydraulic cylinder disposed about said piston portion of said valve needle, a hydraulic fluid disposed within said hydraulic cylinder, wherein said opening and closing forces applied to said valve needle are transmitted through a thickness of said hydraulic fluid whereby said hydraulic fluid acts as a hydraulic link and said thickness is automatically adjustable in response to changes in the dimensional relationship between components of said injection valve to maintain a desired valve lift when said actuator assembly is activated.