Electromagnetic fuel injector

Claim 1

An electromagnetic fuel injector including an electromagnetic coil, a core defining therein a central bore for passing fuel into the injector, a substantially tubular fuel adjuster disposed in said central bore and defining a fuel passage, said fuel adjuster having an upstream end spaced a distance downstream from an inlet end of said central bore, said central bore in said core having a substantially frusto-conical inner peripheral surface portion disposed between said inlet end of said central bore and said upstream end of said fuel adjuster and converging toward said fuel adjuster to cause a laminar flow of the fuel toward and into said fuel adjuster, a support ring fixed to an inlet end of said frusto-conical inner peripheral surface portion of said central bore, and a substantially frusto-conical filter supported by said support ring and having a frusto-conical outer peripheral surface disposed inwardly of and extending substantially along said frusto-conical inner peripheral surface portion, wherein said frusto-conical surface portion is substantially similar to an imaginary frusto-conical plane generated by revolution of a line which interconnects an inner peripheral edge of an upstream end of said fuel adjuster and an inner peripheral edge of a downstream end of said support ring; said filter has a portion having a frusto-conical outer peripheral surface positioned between said frusto-conical peripheral surface portion of said core and said imaginary frusto-conical plane and being substantially similar thereto; and said filter has a downstream end portion having an arcuate form as viewed in an axial section and spaced from said upstream end of said fuel adjuster a distance substantially equal to an inside diameter of said fuel adjuster.