Abstract: The present invention provides a method and apparatus for determining the viscosity range and/or oil grade of an actuating fluid in a fuel system. The method includes the steps of determining a flow, pressure, and temperature of the actuating fluid, and responsively determining the viscosity range and/or oil grade of the actuating fluid.

Abstract: The present solenoid stator assembly is adapted to be mounted upon a mounting seat of a fuel injector valve. The assembly includes a housing having an upper end, a lower end, and a base adapted to fit on the mounting seat of the fuel injector valve. A substantially E-shaped stator core is disposed within the housing. The stator core includes a top portion having a first end and a second end. A first outer pole piece depends substantially perpendicularly from the first end, and a second outer pole piece depends substantially perpendicularly from the second end. The central pole piece is located substantially central to the first and second outer pole pieces, and depends substantially perpendicularly from the top portion in a direction substantially parallel to that of the first and second outer pole pieces. The first and second outer pole pieces and the central pole piece each have a distal end forming a face, each face being substantially flush with the base of the housing.

Abstract: An actuation valve for a hydraulically-operated fuel injector includes an actuator having a plunger and a spool valve coupled to the plunger. The spool valve includes a high pressure port and is operable by the actuator to selectively place the high pressure port or the low pressure port in fluid communication with an injection mechanism of the injector.

Abstract: Electromagnetic actuators having a coil and an armature are used in a number of applications in which it is useful to have an indication of the position of the armature with respect to the coil without the use of external sensors. Accordingly, an actuator control system is provided for determining the position of the armature with respect to the coil in response to the magnitude and rate of change of current flowing in the coil.