Fuel injector pump system with high pressure post injection
AssigneeRobert Bosch GmbH
InventorsSree Menon, Brent Brower
Life of this patent
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Abstract
High pressure post injection using only one valve is accomplished by fluidly connecting the control valve (76) in a fuel injection chamber (70) of a fuel injector (60), and connecting the upper nozzle to a reservoir (80) by way of a restriction. The restriction creates enough residual pressure in the fuel circuit to enable high pressure post injection by closing the control valve (76) a second time.
Claims8
A pump system for a fuel injection system in a diesel engine, the pump system having:
- a pumping chamber;
- a plunger disposed in the pumping chamber for pressurizing fuel;
- a fuel injector having an upper nozzle chamber, a lower nozzle chamber and a needle valve biased to a closed position by a spring wherein higher pressure in the lower nozzle chamber than in the upper nozzle chamber opens the needle valve and the spring closes the needle valve when pressure in the lower nozzle chamber is not higher than in the upper nozzle chamber;
- a fluid line connecting the pumping chamber to the lower nozzle chamber;
- and
- a control valve fluidly connected between the pumping chamber or the fluid line and the upper nozzle chamber, wherein the upper nozzle chamber is fluidly connected to a reservoir with a restriction between the upper nozzle chamber and the reservoir, whereby a high pressure post injection event can occur without the need for a second control valve.
A method of providing high pressure post injection in a fuel injection system wherein a control valve is fluidly connected between a high pressure fluid source and an upper nozzle chamber in a fuel injector, and the upper nozzle chamber is fluidly connected to a reservoir by way of a restriction characterized by:
- closing the control valve after a main injection event whereby residual pressure in the fuel circuit caused by the restriction is sufficient to enable high pressure post injection.
Dependencies are inferred from the claim text.