Means for improving the opening response of a solenoid operated fuel valve

Abstract

Because of inherent delay in magnetic flux propagation in the magnetic circuit, the transient opening magnetic force on the armature does not build as rapidly as the injector driver circuit may be capable of commanding. This transient force is augmented without increasing the package size of the magnetic circuit. A fuel injector has a novel solenoid actuator magnetic circuit that has slots, convolutions, or the like dispersed in the surface of the magnetic circuit to provide increased surface area on the magnetic circuit in the direction of the lines of flux generated when the solenoid is energized along a path to the magnetic gap without increasing the overall size of the magnetic circuit. This increased surface area for the skin provides increased flux paths in the magnetic gap during the transient build-up of magnetic force across the gap, thereby improving the response of the armature upon opening. The slots/convolutions themselves and, especially, a novel arrangement of the slots/convolutions provide a resistivity increasing means for increasing the resistivity of the magnetic circuit by increasing the path length of the eddy currents that flow normal to the lines of flux in the magnetic circuit.

Dependencies are inferred from the claim text.