Multiple-stroke, spark-ignited engine
AssigneeFord Global Technologies, LLC
InventorsDiana D. Brehob, Todd Arthur Kappauf
Life of this patent
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Abstract
A system and a method for operating an internal combustion engine at a six-stroke, eight-stroke, or greater number of strokes cycle is disclosed. The combustion of the fuel and air is accomplished in two combustion steps with at least one expansion and compression process in between the two combustions, with the second combustion occurring at a stoichiometric air-fuel ratio. The first combustion at lean air-fuel ratio provides high efficiency. The products of the first combustion are subjected to a second combustion event at stoichiometric air-fuel ratio. Consequently, high conversion efficiency of nitrogen oxides in the exhaust aftertreatment device, available at stoichiometric conditions, can be achieved.
Claims20
A method of operating an internal combustion engine, said engine has at least one cylinder in which a fuel injector is disposed, said method comprising the steps of:
- inducting air into the cylinder of the engine;
- compressing said air during a first engine compression stroke;
- providing a first amount of a fuel to said air;
- combusting said first amount of said fuel in said air by a first combustion, said first amount of fuel is an amount which when mixed with said air causes contents of the cylinder to have an air-fuel ratio which is leaner than stoichiometric;
- expanding and compressing products of said first combustion during a subsequent expansion and compression stroke;
- providing a second amount of said fuel to said products of said first combustion, said second amount of said fuel is an amount which when mixed with said products of said first combustion causes contents of the cylinder to have an air-fuel ratio which is substantially stoichiometric;
- and
- combusting said second amount of said fuel by a second combustion.
A method for operating an internal combustion engine with the combustion events in each cylinder of the engine being lean every other event and being stoichiometric in between said lean combustion events, the method comprising the steps of:
- providing an amount of air and an amount of fuel to the cylinder, said amount of fuel is less than a stoichiometric amount of fuel;
- combusting said fuel in said air, wherein products of a first combustion are formed;
- providing a second amount of fuel to said products of said first combustion, said second amount of fuel is an amount which causes a mixture of said second amount of fuel and said products of said first combustion to be stoichiometric;
- and
- combusting said mixture in a second combustion.
An internal combustion engine having at least one cylinder comprising:
- a fuel injector to supply fuel to the cylinder;
- a spark plug coupled to the cylinder;
- and
- an engine control unit to provide a signal to said fuel injector to provide a first amount of fuel to the cylinder, a signal to said spark plug to initiate a first combustion of said first amount of fuel, and a signal to said fuel injector to provide a second amount of fuel to the cylinder, wherein said second amount of fuel is an amount which when mixed with products of said first combustion causes contents of the cylinder to have an air-fuel ratio which is substantially stoichiometric.
Dependencies are inferred from the claim text.