Fuel cut solenoid valve for fuel injection pump

Claim 1

In a fuel injection pump having a fuel passage, a fuel cut solenoid valve for opening and closing the fuel passage, comprising: a cylinder made of non-magnetic metal and having first and second ends; a hollow plunger arranged to move in the cylinder, and arranged to move between a first position opening said fuel passage and a second position closing said fuel passage, wherein a first end of the plunger protrudes from the cylinder when the plunger is in the first position; a solenoid placed around said cylinder, and, when energized, for urging the plunger toward the first position, wherein magnetic field lines are directed through the plunger and out of said first end of the plunger when the solenoid is energized; a clearance space between the hollow plunger and the cylinder, wherein magnetic field lines passing through the plunger are directed away from the clearance space; a spring for biasing the plunger toward the second position; a stopper made of a non-magnetic material, mounted on the plunger and, when the solenoid is energized, for abutting the first end of the cylinder and thereby holding the plunger in the first position, wherein the stopper physically separates the first end of the plunger from the clearance space; a chamber defined by the cylinder and the hollow plunger, wherein the volume of the chamber varies as the plunger moves; a relatively large-diameter transverse port disposed substantially near said first end of the plunger, and for providing constant communication between the chamber and the fuel passage; a well opening into said transverse port and for collecting magnetic particles, wherein the well is centrally disposed in the plunger and nearer to the first end of the plunger than the transverse port, and wherein magnetic field lines are conducted through the plunger substantially near the well.