Spill valve assembly for improved minimum delivery capability in fuel system
AssigneeCaterpillar Inc.
InventorsDana Coldren, Sana Mahmood
Life of this patent
Estimating the term…
Abstract
A fuel system for an internal combustion engine includes a nozzle, a fuel pump, a spill valve assembly, and a pumping control unit. The spill valve assembly includes a first spill valve and a second spill valve fluidly in parallel between a plunger cavity in the fuel pump and a low pressure space. A pumping control unit commands closing of the first spill valve and then the second spill valve to adjust the spill valve assembly to start pressurization in the fuel pump, and commands opening the first spill valve to end pressurization in the fuel pump. A pumping duration is determined based on a timing of the commanded closing of the second spill valve and a timing of the commanded opening of the first spill valve.
Claims20
A fuel system for an internal combustion engine comprising:
- a fuel injection nozzle;
- a fuel pump including a plunger coupled to a tappet and structured to pressurize a fuel for injection into the internal combustion engine through the fuel injection nozzle, the fuel pump defining a low pressure space, a high pressure outlet, and a plunger cavity receiving the plunger and fluidly connected to the high pressure outlet;
- a spill valve assembly including a first spill valve and a second spill valve fluidly in parallel with one another between the plunger cavity and the low pressure space, and each of the first spill valve and the second spill valve being movable between an open position where the plunger cavity is fluidly connected to the low pressure space, and a closed position;
- a pumping control unit in control communication with the first spill valve and the second spill valve, the pumping control unit being structured to:
- command closing of the first spill valve;
- command closing of the second spill valve after the closing of the first spill valve to adjust the spill valve assembly to a start-of-pressurization configuration;
- command opening of the first spill valve while the second spill valve remains closed to adjust the spill valve assembly from the start-of-pressurization configuration to a start of spill configuration;
- and
- determine a pumping duration of the fuel pump based on a timing of the commanded closing of the second spill valve and a timing of the commanded opening of the first spill valve.
A fuel system for an internal combustion engine comprising:
- a fuel supply;
- a plurality of fuel injection nozzles;
- a cam;
- a fuel pump including a plunger coupled to a tappet in contact with the cam and structured to pressurize a fuel for injection into the internal combustion engine through at least one of the plurality of fuel injection nozzles, the fuel pump defining a low pressure space, a high pressure outlet, and a plunger cavity receiving the plunger and fluidly connected to the high pressure outlet;
- a spill valve assembly including a first spill valve and a second spill valve arranged fluidly in parallel with one another between the plunger cavity and the low pressure space;
- and
- the spill valve assembly having a first configuration where each of the first spill valve and the second spill valve is open, and being adjustable to a start-of-pressurization configuration where each of the first spill valve and the second spill valve is closed, and to a start of spill configuration where the first spill valve is open and the second spill valve remains closed.
A method of operating a fuel system for an internal combustion engine comprising:
- spilling fuel from a plunger cavity in a fuel pump through each of a first spill valve and a second spill valve in a spill valve assembly to a low pressure space, during moving a plunger in the fuel pump between a retracted position and an advanced position;
- closing the first spill valve in the spill valve assembly;
- closing a second spill valve in the spill valve assembly after the closing of the first spill valve to start pressurization of fuel within the plunger cavity;
- conveying pressurized fuel from the plunger cavity to a high pressure outlet of the fuel pump;
- opening the first spill valve while the second spill valve remains closed to end pressurization of fuel within the plunger cavity at a timing determining a pumping duration of the fuel pump;
- and
- feeding the pressurized fuel from the high pressure passage to a nozzle supply passage in a fuel injection nozzle.
Dependencies are inferred from the claim text.