Internal-combustion engines – Charge forming device – Diverse fuel supply
Reexamination Certificate
1999-11-04
2001-09-04
Solis, Erick (Department: 3747)
Internal-combustion engines
Charge forming device
Diverse fuel supply
C123S436000, C123S00100A
Reexamination Certificate
active
06283102
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention generally relates to a software algorithm for controlling the engine of a motor vehicle. More particularly, but without restriction to the specific embodiment and/or use which is shown and described for purposes of illustration, the present invention pertains to a fuel identifier algorithm capable of distinguishing the difference between normal fuel and high driveability index fuel.
2. Discussion
In recent years, the manufacturers of internal combustion engine fuel have began to offer a variety of different fuels having vaporization pressures to correspond with the climate in which they are sold. For example, fuels exhibiting a Reid vaporization pressure of approximately 7-9 psi are commonly sold in the warmer climate regions of the country or only during the summer. Similarly, fuels exhibiting Reid vaporization pressures of 12-14 psi are utilized primarily in the winter. By varying the vaporization pressure to correspond to the average daily temperature, the cold start characteristics of the internal combustion engine may be optimized.
One of the specific problems attempted to be solved by varying the vapor pressure of the fuel is a warm weather phenomenon known as vapor lock. If the ambient temperature is high and the fuel volatility or vapor pressure is also high, the fuel may vaporize on its way to the fuel injection system. Accordingly, the fuel will not pump and the engine will stall due to lack of fuel. Conversely, a different concern exists during cold weather. For example, an engine may fail to start during a cold weather snap if a fuel exhibiting a high driveability index or low vapor pressure is used. Specifically, the fuel may simply wet the walls of the cylinder without vaporizing thereby precluding combustion. Accordingly, the engine will not start and the fuel will be pumped through the combustion chambers and into the exhaust.
With the advent of the use of high driveability index fuel, engine control systems face a new challenge. Specifically, accommodations must be made to assure that the engine will start easily and meet strict emission standards regardless of ambient temperature or fuel type. This goal is more complex since fuels of high driveability index may be in the tanks of vehicles during a seasonal change or a cold snap. As emission standards are tightened, it becomes increasingly difficult to meet both the emission standard and an acceptable level of driveability robustness as determined by the customer. Accordingly, a need exists for a method to identify when high driveability index fuel is present and modify the enrichment/control strategy to compensate for the fuel's lower volatility.
In the past, systems commonly known in the art would simply enrich the mixture at start for all fuels in an attempt to assure an easy start. However, this strategy is no longer viable when evaluated using the emission standards of today. One of the greatest hurdles facing original equipment manufacturers is that the vehicle must meet not only a new car emission standard but must also pass an audit performed up to three years after the initial sale. Recently developed systems have attempted to assure that the emission standards were met over time by setting the initial enrichment to a goal maximum roughness setting equivalent to the most lean setting acceptable. This control strategy would allow the emissions level to increase over time as the engine components wear. However, if a fuel of lesser volatility were used, the engine would be pushed into roughness thereby dissatisfying the operator.
SUMMARY OF THE INVENTION
Accordingly, an object of the present is to provide a fuel identifier algorithm capable of identifying high driveability index fuel and modifying the enrichment strategy to compensate for low volatility fuel.
It is another object of the present invention to provide a fuel identifier algorithm for controlling an engine to operate within driveability robustness and emissions limitations while burning fuels of varying driveability index.
The present invention provides a method for identifying high driveability index fuel for use in a motor vehicle engine. The method includes the steps of determining an engine rotational speed after the engine has started, measuring an elapsed time required for the engine rotational speed to increase from a predetermined low limit to a predetermined high limit, and identifying high driveability index fuel when the elapsed time is greater than a predetermined time limit.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from a reading of the subsequent description of the preferred embodiment and the appended claims, taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5226396 (1993-07-01), Bailey
patent: 5435285 (1995-07-01), Adams et al.
patent: 5537978 (1996-07-01), Watanabe
patent: 5586537 (1996-12-01), Tomisawa et al.
patent: 5817923 (1998-10-01), Ohsaki et al.
patent: 5881703 (1999-03-01), Nankee et al.
patent: 5893349 (1999-04-01), Rado
patent: 5901671 (1999-05-01), Huff et al.
patent: 5957994 (1999-09-01), Meyer et al.
patent: 6016796 (2000-01-01), Dalton
patent: 6079396 (2000-06-01), Ament et al.
patent: 4-252835 (1992-09-01), None
Adams Joseph B.
Alicke Luiz R.
Nelson Brian J.
Wielenga Jason E.
Calcaterra Mark P.
DaimlerChrysler Corporation
Solis Erick
LandOfFree
Fuel identifier algorithm does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fuel identifier algorithm, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fuel identifier algorithm will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2448676