Abstract: A fuel injector system (10) calculates a first derivative filtered signal and a second derivative filtered signal from an unpowered spool valve coil signal. When the spool valve (16) reaches the end of travel, either open or closed position, a flat slope f is generated on the falling edge of the bell shaped signal. The second derivative provides a readily apparent determination of when the steep slope occurs. A comparator (62) thereby need only determine when the second derivative is zero to identify that the spool valve has reached the end of travel.

Abstract: A fuel injector system 10 calculates a first derivative filtered signal and a second derivative filtered signal from an unpowered spool valve coil signal. When the spool valve 16 reaches the end of travel, either open or closed position, a flat slope f is generated on the falling edge of the bell shaped signal. The second derivative provides a readily apparent determination of when the steep slope occurs. A comparator 62 thereby need only determine when the second derivative is zero to identify that the spool valve has reached the end of travel.

Abstract: An engine valve assembly includes an engine valve (12) connected to an electric motor (30.) The electric motor may be a linear electric motor (34) which includes “rare earth” magnets to infinitely move the engine valve (12) between an open and closed position. Usage of “rare earth” magnets assures that the linear electric motor (34) generates enough force to properly and timely operate the engine valve (12.) The electric motor (30) may alternatively drive a threaded portion (42) of the valve stem (18.) Operation of the electric motor (30) threads the threaded valve stem (18) relative to a threaded support (40) to drive the engine valve (12′) between an open and a closed position.