Sleeve metered unit pump and fuel injection system using the same
AssigneeCaterpillar Inc.
InventorsDennis H. Gibson, Mark F. Sommars
Life of this patent
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Abstract
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.
Claims12
A fuel injection system comprising:
- a common rail;
- a plurality of fuel injectors fluidly connected to said common rail;
- a source of fluid;
- a sleeve metered pump with an outlet fluidly connected to said common rail and an inlet fluidly connected to said source of fluid;
- an inlet check valve fluidly positioned between said source of fluid and a pump chamber of said sleeve metered pump;
- said sleeve metered pump including a solenoid assembly, at least one plunger that defines a vent and is positioned to reciprocate a stroke distance in a pump housing;
- said solenoid assembly includes a coil disposed around said at least one plunger and a metering sleeve slidably mounted on each said at least one plunger;
- and
- a camshaft operably coupled to said pump and being rotatable with respect to said at least one plunger.
A method of controlling output from a sleeve metered pump in a common rail fuel injection system, comprising the steps of:
- providing a sleeve metered pump that includes at least one plunger positioned to reciprocate a stroke distance in a pump housing and defining at least one vent, and further includes a solenoid assembly with a coil disposed around said at least one plunger and a metering sleeve slidably mounted on each said at least one plunger;
- determining a desired effective pumping stroke for said sleeve metered pump;
- determining a solenoid current magnitude that corresponds to said desired effective pumping stroke;
- adjusting a position of said metering sleeve by supplying current to said solenoid assembly at a level corresponding to said solenoid current magnitude;
- pumping fluid at least in part by rotating a camshaft, which is operably coupled to said sleeve metered pump, with respect to said at least one plunger;
- and
- refilling a pump chamber at least in part by opening an inlet check valve fluidly positioned between the pump chamber and a source of fluid.
Dependencies are inferred from the claim text.