Directly actuated injection valve

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 valve seat provided on an end of said housing that faces said combustion chamber;
• (b) a valve member comprising a shaft portion having a first end to which a circular head is transversely mounted wherein said head provides an annular sealing surface that faces said valve seat, and a second end of said shaft is associated with a piston portion, said valve member movable between a closed position at which said sealing surface contacts said valve seat to fluidly seal said interior chamber from said combustion chamber, and an open position at which said sealing surface is spaced apart from said valve seat whereby said interior chamber is fluidly connected with combustion chamber;
• (c) a biasing mechanism associated with said piston portion of said valve member, said biasing mechanism applying a closing force to said valve member when said valve member is in said closed position;
• (d) an actuator assembly for applying an opening force to said valve member that is stronger than said closing force, for moving said valve member to said open position, said actuator assembly comprising a member having dimensional responsiveness to the imposition of at least one of an electric current, an electric voltage and a magnetic field, said dimensionally responsive member disposed between a fixed pole maintained in a fixed position relative to said valve housing and a sliding pole, said sliding pole being displaceable by expansion of said dimensionally responsive member;
• and
• (e) a hydraulic link assembly comprising a fluidly sealed hydraulic cylinder disposed about said piston portion of said valve member, a hydraulic fluid disposed within said hydraulic cylinder, wherein said opening and closing forces applied to said valve member 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 upon actuation of said actuator assembly.

A method of using a shaped waveform to control electric current to actuate an injection valve for an internal combustion engine that employs a dimensionally responsive actuator assembly comprising at least one of a magnetostrictive and a piezoelectric material, and a controller to govern valve lift and duration according to values predetermined for engine load demands within the operating range of said engine by said controller controlling current and voltage directed to said actuator assembly, said method comprising for each injection event:

• (a) initiating an injection event by rapidly increasing current to a magnitude that is known to correspond to a desired lift by applying high frequency voltage cycles and in each cycle maintaining a net positive voltage;
• (b) maintaining a current to control said desired lift for a duration predetermined by said controller;
• and
• (c) concluding an injection event by decreasing current until it is reduced to zero amps by applying high frequency voltage cycles and in each cycle maintaining a net negative voltage.

A method of operating a fuel injection valve for an internal combustion engine, said injection valve having a longitudinal axis, said method comprising:

• (a) actuating a dimensionally responsive member comprising at least one of a magnetostrictive material and a piezoelectric material, said dimensionally responsive member expanding in length in the direction of said longitudinal axis upon actuation of said actuator;
• (b) transferring movement caused by said actuated dimensionally responsive member through a passive hydraulic link to cause a corresponding movement of a valve member to open said valve by lifting said valve member away from a valve seat and compressing a biasing mechanism that biases said valve in a closed position, said passive hydraulic link comprising a hydraulic cylinder which houses a piston and is filled with a hydraulic fluid, wherein said hydraulic fluid forms a layer between said piston and a cylinder head and because of the short duration that said valve is open, said hydraulic fluid does not have time to flow from one side of said piston to the other side and while said injection valve is open, said layer of hydraulic fluid acts as an incompressible solid so that movement caused by the actuation of said dimensionally responsive member is transmitted through said fluid layer;
• (c) deactuating said dimensionally responsive member to contract the length of said dimensionally responsive member to unload said biasing mechanism and cause a corresponding movement of said valve member to close said valve;
• (d) providing sufficient time between consecutive valve openings to allow at least some of said hydraulic fluid within said passive hydraulic link to flow from one side of said piston to the other side of said piston.