Power plants – Internal combustion engine with treatment or handling of... – By means producing a chemical reaction of a component of the...
Reexamination Certificate
2000-08-29
2002-03-26
Denion, Thomas (Department: 3748)
Power plants
Internal combustion engine with treatment or handling of...
By means producing a chemical reaction of a component of the...
C060S274000, C060S285000, C123S090150, C123S090110, C123S299000, C123S478000
Reexamination Certificate
active
06360531
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a system and method for reducing cold-start emissions and more particularly, to a system and method for reducing vehicle emissions which synergistically utilizes variable valve timing, ignition timing and air/fuel ratio enleanment strategies to achieve rapid catalyst “light off”, thereby reducing emissions during cold-start conditions.
BACKGROUND OF THE INVENTION
Automotive vehicles having internal combustion engines typically utilize a three-way-catalyst (“TWC”) to reduce tailpipe emissions. Particularly, the TWC catalytically reduces nitrogen oxides (NOx) and oxidizes carbon monoxide (“CO”) and unburned hydrocarbons (“HC”) which are produced during the combustion process. The TWC has a very high conversion efficiency once the catalyst has “warmed up” and the air/fuel ratio of the mixture is near its stoichiometric point.
The point in time at which the catalytic converter reaches a fifty percent (50%) efficiency is commonly referred to as its “light-off” time. Due to the relatively poor efficiency of the catalytic converter prior to “light-off”, recent efforts to reduce tailpipe emissions have concentrated on reducing the “light-off” time, thereby reducing the time during which the catalytic converter is least efficient. These prior efforts have also included concomitantly altering the air/fuel ratio and/or retarding the spark calibration of the engine. These efforts are commonly referred to as Coordinated Strategies for Starting with Reduced Emissions or “CSSRE”, and are described for example and without limitation in U.S. Pat. Nos. 5,483,946 and 5,584,176, which are fully and completely incorporated herein by reference.
These prior efforts have suffered from some drawbacks. Particularly, the difficulty in controlling the combustion quality and stability of the engine, noise and vibration harshness, and vehicle “drivability” as the vehicle warms up limit the application of these prior strategies.
There is therefore a need for a system and method for reducing vehicle cold-start emissions which overcomes the drawbacks of prior emissions reducing methods, strategies and systems.
SUMMARY OF THE INVENTION
It is a first object of the invention to provide a system and method for reducing vehicle cold-start emissions which overcomes at least some of the previously delineated drawbacks of prior emissions reducing methods and strategies.
It is a second object of the invention to provide a system and method for reducing vehicle cold-start emissions which synergistically utilizes variable valve timing, ignition timing and air/fuel ratio enleanment strategies to achieve rapid catalyst “light off”, thereby reducing emissions during cold-start conditions.
It is a third object of the invention to provide a system and method for reducing vehicle cold-start emissions which utilizes direct and/or indirect feedback to adapt ignition timing, air/fuel ratio enleanment, and valve timing events to achieve optimum emissions reduction and vehicle drivability.
It is a fourth object of the invention to provide a system and method for reducing vehicle cold-start emissions which utilizes variable valve timing events to expand the operational ranges of CSSRE ignition timing and air/fuel ratio enleanment schedules without deterioration of combustion quality and vehicle drivability (e.g., NVH issues).
It is a fifth object of the invention to provide a system and a method for reducing vehicle cold-start emissions which utilizes camless valve actuators to assist in fuel preparation during cold-start operating conditions.
It is a sixth object of the invention to provide a system and a method for reducing vehicle cold-start emissions which utilizes multiple valve events during a single intake stroke to reduce the amount of fuel deposited on a valve, thereby increasing evaporation of the fuel and improving combustion. Additionally, multiple openings of the intake valve may also improve combustion through better air/fuel mixture preparation by increasing in-cylinder fuel shearing and turbulence.
According to a first aspect of the present invention, a method is provided for reducing emissions of a vehicle of the type having an engine. The method includes the steps of detecting a cold-start condition; and selectively and synergistically altering valve timing, spark timing, and air/fuel delivery to the engine, effective to extend air/fuel enleanment limits, to improve combustion characteristics, and to increase exhaust gas temperature, thereby reducing cold-start emissions.
According to a second aspect of the present invention, a method is provided for reducing emissions of a vehicle of the type having an engine including a combustion chamber with at least one valve and a fuel injector which discharges an amount of fuel which is delivered to the chamber through the at least one valve. The method includes the step of selectively opening and closing the at least one valve multiple times during an intake stroke of the engine, thereby increasing vaporization of the amount of fuel, effective to increase combustion efficiency and exhaust gas temperature, thereby reducing emissions. Additionally, multiple openings of the intake valve may also improve combustion through better air/fuel mixture preparation by increasing in-cylinder fuel shearing and turbulence.
These and other features, aspects, and advantages of the invention will become apparent by reading the following specification and by reference to the following drawings.
REFERENCES:
patent: 4327689 (1982-05-01), Rachel
patent: 4719885 (1988-01-01), Nagano et al.
patent: 5076238 (1991-12-01), Rosenau et al.
patent: 5228422 (1993-07-01), Wakeman
patent: 5231962 (1993-08-01), Osuka et al.
patent: 5233831 (1993-08-01), Hitomi et al.
patent: 5293741 (1994-03-01), Kashiyama et al.
patent: 5398502 (1995-03-01), Watanabe
patent: 5531203 (1996-07-01), Komatsuda et al.
patent: 5590633 (1997-01-01), Tomisawa et al.
patent: 5839453 (1998-11-01), Hu
patent: 5850811 (1998-12-01), Tomisawa et al.
patent: 5890467 (1999-04-01), Romzek
patent: 6032642 (2000-03-01), Trumbower et al.
patent: 6055948 (2000-05-01), Shiraishi et al.
patent: 6128899 (2000-10-01), Oono et al.
patent: 6134884 (2000-10-01), Morinaga
patent: 6182621 (2001-02-01), Salber et al.
Husak Philip William
Meyer Daniel Lawrence
Stockhausen William Francis
Wiemero Timo Aimo Waltteri
Denion Thomas
Ford Global technologies, Inc.
Ford Global technologies, Inc.
Tran Binh
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