Patent ID: 8444070

Claim:
A unit fuel injector comprising: a plunger operable within a bore along an imaginary longitudinal axis to force an injection of fuel from the unit injector; a source of pressurized oil; and a control valve for opening the source of pressurized oil to the bore to cause the plunger to force a fuel injection and for closing the source of pressurized oil to the bore to terminate a fuel injection; the control valve comprising a valve body having an oil inlet port open to the source of pressurized oil, an oil outlet port open to the bore, an oil drain port, and a valve spool that is displaceable within a bore of the valve body between a limit of displacement that fully opens the oil outlet port to the oil inlet port while closing the oil drain port to the oil outlet port and a limit of displacement that closes the oil outlet port to the oil inlet port while opening the oil outlet port to the oil drain port; the valve spool comprising a spool body having a geometry that defines an exterior envelope of the valve spool and a bore extending through the spool body parallel with the valve body bore, the valve spool further comprising at least one permanent magnet disposed within the spool body bore inside of the exterior envelope of the valve spool; and the control valve comprising at least one electromagnet electromagnetically coupled with the at least one permanent magnet for displacing the valve spool within the valve body bore.