Sleeve metered unit pump and fuel injection system using the same

摘要

Pressurized injector actuation fluid, such as oil or fuel, is supplied to high pressure common rail by a fixed displacement fluid pump. Variable delivery from the pump is achieved by an improved sleeve metering approach. The sleeve surrounds the reciprocating piston and is manipulated to control venting of pumped fluid through vent ports in the piston. The sleeve is moved by preferably being the armature of a solenoid assembly. The varying of current to the solenoid coil alters the axial position of the sleeve relative to the piston to vary the effective pumping stroke of the piston.