Electronically controlled inlet metered single piston fuel pump
AssigneeStanadyne, Inc.
InventorRobert G. Lucas
Life of this patent
Estimating the term…
Abstract
In a fuel pump and method of operation, an infeed for low pressure fuel leads to a pumping chamber where in an intake phase low pressure fuel is drawn into the pumping chamber and in a pumping phase high pressure fuel is delivered to a common rail. An inlet metering valve and an inlet check valve are upstream of the pumping chamber, and a control system closes the metering valve when no fuel is to be pumped to the common rail. The inlet check valve is also opened while the inlet metering valve is closed and no fuel is to be pumped to the rail. The inlet metering valve can include a proportionally controlled piston that produces a variable quantity of feed fuel and is closable for the no-demand condition with a maximum travel that contacts and holds open the inlet check valve.
Claims16
A fuel pump comprising:
- an infeed passage for low pressure feed fuel;
- a pumping chamber in fluid communication with the infeed passage;
- a pumping plunger reciprocable in the pumping chamber between an intake phase that draws low pressure fuel from the infeed passage into the pumping chamber and pumping phase that increases the pressure in the pumping chamber to a higher pressure for delivery to a common rail through a discharge valve;
- an inlet metering valve in the infeed passage for delivering metered quantities of low pressure feed fuel through a variable opening to the pumping chamber, said inlet metering valve having an inlet metering valve member movable between an open position corresponding to maximum flow through the variable opening and a closed position of the metering valve corresponding to zero flow through the variable opening to the pumping chamber;
- an inlet check valve between the metering valve and the pumping chamber, biased against a seat to permit feed flow to the pumping chamber during the intake phase and to prevent fuel pumped at high pressure from flowing into the infeed passage during the pumping phase;
- an actuator operatively connected to move and maintain said inlet metering valve member in positions between said open and closed positions during said intake phase to vary the opening of the inlet metering valve commensurate with an infeed fuel quantity demand for the intake phase in the pumping chamber;
- and
- means for opening the inlet check valve while the inlet metering valve is in said closed position.
A method of operating a fuel pump with an infeed passage for low pressure fuel;
- a pumping chamber in fluid communication with the infeed passage;
- a pumping plunger continuously reciprocable in the pumping chamber commensurate with engine speed between an intake phase that draws low pressure fuel from the infeed passage into the pumping chamber and pumping phase that increases the fuel pressure in the pumping chamber for delivery to a common rail through an outlet check valve;
- a metering valve in the infeed passage for delivering metered quantities of low pressure fuel to the pumping chamber, said metering valve including a metering valve element movable between an open position corresponding to maximum flow through said infeed passage and a closed position corresponding to no flow through said infeed passage;
- an inlet check valve between the inlet metering valve and the pumping chamber, biased to permit feed flow to the pumping chamber during the intake phase and prevent fuel pumped at high pressure from flowing into the infeed passage during the pumping phase;
- and a control system that displaces the metering valve element among positions maintained between said open and closed positions during said intake phase according to demand for pumped fuel, said control system closes the metering valve when no fuel is to be pumped to the common rail;
- wherein the improvement comprises a step wherein the control system opens the inlet check valve while the inlet metering valve is closed and no fuel is to be pumped to the common rail.
Dependencies are inferred from the claim text.