Fuel injector control system and method

A method of operating a fuel injector for an internal combustion engine having a crankshaft, the method comprising:

• cammingly driving a plunger within a bore to pressurize fuel;
• directing the pressurized fuel to at least one orifice of a nozzle member and to the base end of a valve needle disposed within the nozzle member;
• receiving an indication of a desired start of injection timing relative to an angular position of the crankshaft, and a desired injection quantity;
• and
• electronically moving a check valve to drain the pressurized fuel from the base end of the valve needle to allow the pressurized fuel to flow through the at least one orifice at the desired start of injection timing in the amount of the desired injection quantity, wherein moving includes:
• determining a start of current for the electronically controlled check valve relative to plunger displacement within the bore that results in the desired start of injection timing;
• determining an end of current for the electronically controlled check valve relative to plunger displacement within the bore that results in the desired injection quantity;
• and
• affecting the determined start and end of current for the electronically controlled check valve.

An internal combustion engine, comprising:

• an engine block having at least one combustion chamber;
• a crankshaft rotatingly disposed within the engine block;
• and
• a fuel system including:
• a fuel injector configured to inject a desired quantity of pressurized fuel into the combustion chamber at a desired timing, the fuel injector including:
• plunger reciprocatingly disposed within a bore to pressurize fuel within the bore;
• a nozzle member having a tip end with at least one orifice;
• a valve needle having a base end and tip end, being disposed within the nozzle member, and movable against a spring bias to allow a flow of pressurized fuel through the at least one orifice;
• an electronically controlled check valve in fluid communication with the bore and the base end of the valve needle, the electronically controlled check valve movable between a first position at which the bore is fluidly communicated with the base end of the valve needle, and a second position at which the base end of the valve needle is fluidly communicated with a drain;
• a cam mechanism operably connected to the crankshaft and configured to drive the plunger;
• a sensor configured to sense an angular position of the crankshaft;
• and
• a controller in communication with the electronically controlled check valve and the sensor, the controller configured to:
• receive an indication of a desired start of injection timing relative to the angular position of the crankshaft, and a desired injection quantity;
• determine a displacement of the plunger based on the sensed angular position of the crankshaft;
• determine a start of current for the electronically controlled check valve relative to plunger displacement within the bore that results in the desired start of injection timing;
• determine an end of current for the electronically controlled check valve relative to plunger displacement within the bore that results in the desired injection quantity;
• and
• affect the determined start and end of current for the electronically controlled check valve.