Internal-combustion engines – Accessories – Covers – trays – vibrators – corrosion inhibitors – air filters
Reexamination Certificate
2000-08-02
2001-07-10
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Accessories
Covers, trays, vibrators, corrosion inhibitors, air filters
C123S19800E
Reexamination Certificate
active
06257194
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a method for shutting down an internal combustion engine equipped with electronically deactivatable valves so as to minimize fuel evaporative emissions into the atmosphere.
BACKGROUND OF THE INVENTION
One mode by which vehicles may emit pollutants is during inactive periods in which fuel is vaporized and released from the vehicle into the atmosphere. The allowable levels of evaporative emissions is continually being decreased. As a consequence, vehicle manufacturers have developed and installed systems for managing fuel vapors emanating from fuel tanks. Also, measures are taken to reduce the amount of unburned fuel residing in the engine which could be released into the atmosphere during periods during which the vehicle is not operating.
The inventors of the present invention have recognized that engines equipped with electronically deactivatable valves present an opportunity for managing unburned fuel during an engine shutdown procedure not possible with conventional engines which have no provision for disabling the valves.
SUMMARY OF THE INVENTION
An object of the invention claimed herein is to provide a method for ceasing operation of an internal combustion engine having a throttle valve and a plurality of cylinders, each of the cylinders having a spark plug, electronically deactivatable intake and exhaust valves, and an adjoining intake port having a fuel injector. The method includes the steps of sensing a demand for cessation of engine operation, and determining whether the fuel injector has injected fuel since the occurrence of a corresponding and immediately prior combustion event. If it is determined that fuel has not been injected since the occurrence of the corresponding and immediately prior combustion event, perform a trapping intake event. If it is determined that fuel has been injected since the occurrence of the corresponding and immediately prior combustion event, perform a first intake event to induct injected fuel into said cylinder and perform a combustion event to burn the fuel.
The inventors herein have recognized that an engine equipped with deactivatable valves has the potential for trapping unburned fuel within the cylinder during a shutdown procedure of an engine, a measure which is not possible with conventional valvetrains. The fuel trapped within the cylinder is prevented from leaving the engine during a vehicle soak period, but is combusted during later engine operation. An advantage in the present invention is managing fuel injected into the engine following a demand for engine cessation which leads to a reduction in evaporative emissions from the vehicle.
Further, an article of manufacture for ceasing operation of an internal combustion engine in response to a demand for engine cessation is provided. The engine has a throttle valve and a plurality of cylinders; each of the cylinders has a spark plug and an adjoining intake port having a fuel injector. The article includes a computer readable program code in the computer usable medium for directing the computer to perform the steps of controlling operation of deactivatable intake and exhaust valves of the engine and the spark plug firing during cessation of engine operation. The computer storage medium comprises means for determining a demand for cessation of engine operation, means for determining whether fuel has been injected into an intake port since a corresponding and immediately prior combustion event within the cylinder, means for performing an intake event and ceasing operation of the intake and exhaust valves, in the event that no fuel has been injected since the corresponding and immediately prior combustion event and means for performing a first intake event and a combustion event in the event that fuel has been injected since the immediately prior combustion event.
In accordance with another aspect of the present invention an article of manufacture including a computer storage medium containing a computer program encoded for controlling operation of intake and exhaust valves of an internal combustion engine and spark plug firing includes means for determining a demand for cessation of engine operation and means for determining whether fuel has been injected into an intake port since a prior combustion event is provided. The article also includes means for performing an intake event and ceasing operation of said intake and exhaust valves, in the event that no fuel has been injected since the prior combustion event, and means for performing a first intake event and a combustion event, in the event that fuel has been injected since the prior combustion event.
Other objects, features, and advantages of the present invention will become apparent to the reader of this specification.
REFERENCES:
patent: 3714932 (1973-02-01), Meacham et al.
Hammoud Mazen
Kerns James Michael
Makki Imad Hassan
Coughlin William J.
Ford Global Technologies Inc.
Hanze Carlos L.
Kamen Noah P.
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