Internal-combustion engines – Accessories – Covers – trays – vibrators – corrosion inhibitors – air filters
Reexamination Certificate
2000-03-01
2001-11-20
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Accessories
Covers, trays, vibrators, corrosion inhibitors, air filters
Reexamination Certificate
active
06318334
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to fuel control for internal combustion engines and, more particularly, to a method of reducing emissions in an internal combustion engine by continuing ignition events subsequent to fuel delivery termination.
BACKGROUND OF THE INVENTION
Environmental concerns have prompted government regulations to curb emissions from internal combustion engines in motor vehicles. Maximum levels of various gases, such as hydrocarbons, that may be emitted from the exhaust system of the motor vehicle are strictly regulated. As such, many attempts have been made to control exhaust system emissions.
One such attempt includes the use of a catalytic converter. In a motor vehicle, a catalytic converter is used to burn off excess emissions from the engine before the exhaust gases exit through the tailpipe. Unfortunately, immediately following a cold engine start, the catalyst of the catalytic converter can be ineffective since the catalyst requires a period of time to warm up to a temperature at which the catalyst can operate effectively to burn excess hydrocarbons. As a consequence, after engine start up, hydrocarbon emissions may initially be high due to a low temperature catalyst. To add to the problem, excess fuel in the catalyst at start up may further cool the catalyst, thereby requiring an extended period of time for the catalyst to warm up to a sufficient operating temperature.
Another attempt includes the use of fuel injectors. In a motor vehicle, fuel injection and engine control strategies are aimed at minimizing exhaust emissions while maintaining engine performance and economy. Conventional fuel injectors are typically controlled by a fuel injection pulsewidth signal in which the pulsewidth determines the amount of fuel injected into the corresponding cylinder of the engine. The fuel injection pulsewidth signal is tailored to follow a programmed target fuel injection curve. The curve is programmed to minimize emissions from the engine during vehicle operation. For example, a stoichiometric air/fuel ratio is used during most operations to reduce hydrocarbon emissions. Further, spark ignition timing can be varied in order to minimize emissions. While these methods may work well during engine operation, they do not address the high emissions that sometimes result after engine shutdown and subsequent restart. (Such as the catalyst cooling described above).
Conventional engine shutdown involves synchronized deactivation of fuel delivery and ignition events. In actuality, these deactivations often do not occur simultaneously; for example, fuel may be delivered to one or more of the cylinders after the final ignition event for that cylinder. This unburned fuel may then pass through the engine and enter into the exhaust system including the catalytic converter. After engine start up, the excess fuel slows the warming of the catalyst and high hydrocarbon emissions may result.
It is therefore desirable to provide a method of minimizing the amount of fuel delivered to the exhaust system after engine shutdown in order to reduce hydrocarbon emissions.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method of reducing the amount of hydrocarbon emissions resulting from excess fuel in the exhaust system following engine shutdown.
The present invention provides a method for reducing hydrocarbon emissions in an engine of a vehicle. Following an ignition shutdown or key-off event, fuel delivery to the engine is terminated. However, spark ignition is continued based on a predetermined parameter such as time or engine cycles. Thereafter, spark ignition is stopped. This method continues combustion until no excess fuel exists in the cylinder. Since there is no over abundance of fuel in the cylinder, no fuel collects in the catalyst. As such, the catalyst quickly warms after engine start up and effectively reduces hydrocarbon emissions.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood however that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 4768480 (1988-09-01), Grenn et al.
patent: 5402762 (1995-04-01), Yamada et al.
patent: 5542403 (1996-08-01), Borland et al.
patent: 5596975 (1997-01-01), Thomas et al.
patent: 5634868 (1997-06-01), Weber et al.
patent: 5809969 (1998-09-01), Fiaschetti et al.
patent: 5842456 (1998-12-01), Morganti
patent: 5901684 (1999-05-01), Fiaschetti et al.
patent: 5947088 (1999-09-01), DeGroot et al.
patent: 6003494 (1999-12-01), DeGroot et al.
patent: 03242466A (1991-10-01), None
DeGroot Kenneth P
Larson Thomas A
Reale Michael J
Teague Bruce H
Ali Hyder
Argenbright Tony M.
Calcaterra Mark P.
DaimlerChrysler Corporation
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