Internal-combustion engines – Combustion chamber means having fuel injection only – Combustible mixture stratification means
Reexamination Certificate
1999-08-31
2001-01-30
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Combustion chamber means having fuel injection only
Combustible mixture stratification means
C123S19800E, C123S478000
Reexamination Certificate
active
06178944
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to direct injection spark ignition engine.
BACKGROUND OF THE INVENTION
In direct spark ignition engines, fuel is injected directly into each combustion chamber. Accordingly, fuel is not inducted past the intake valve.
The inventors herein have discovered a problem with such engines. Because fuel is not inducted past the intake valve in direct injection spark ignition engines, there is no fuel flow to clean carbon deposits which may deposit on the intake valve. Port injected gasoline engines, on the other hand, induct a mixture of gasoline and air past the intake port. This gasoline mixture cleans carbon deposits which would otherwise accumulate on the intake valve.
SUMMARY OF THE INVENTION
An object of the invention herein is to clean carbon deposits which accumulate on and around the intake valve of a direct injection spark ignition engine.
The above object is achieved, problems of prior approaches overcome, and inherent advantages obtained, by providing a control method and system for a spark ignited, four-stroke engine having multiple combustion chambers, each coupled to at least one intake and one exhaust valve, a fuel injection system for injecting fuel directly into each combustion chamber, and an electronically controlled throttle for throttling air inducted through an intake manifold into the combustion chambers. In one particular aspect of the invention, the method comprises: detecting when to initiate an intake valve cleaning; indicating when the engine is operating in a homogeneous mode wherein the throttle is partially closed and fuel is injected during an engine intake stroke to generate a homogeneous air/fuel mixture; and in response to said valve cleaning detection and said homogeneous mode indication, injecting additional fuel during a valve overlap of the intake and exhaust valves so that fuel is drawn into the intake manifold and subsequently inducted back into the combustion chamber past the intake valve to clean valve deposits.
An advantage of the above aspect of the invention is that fuel injected during the valve overlap cleans carbon deposits accumulated on and around the intake valve.
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Cullen Michael John
Kerns James Michael
Argenbright Tony M.
Ford Global Technologies Inc.
Lippa Allan J.
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