Internal-combustion engines – Charge forming device – Including exhaust gas condition responsive means
Reexamination Certificate
1999-10-28
2001-08-28
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Charge forming device
Including exhaust gas condition responsive means
Reexamination Certificate
active
06279560
ABSTRACT:
The present invention relates to a method of controlling injection of an internal combustion engine as a function of fuel quality.
BACKGROUND OF THE INVENTION
As is known, the quality of a fuel, i.e. its chemical and physical characteristics (chemical composition, stoichiometric air/fuel ratio, density and heat value) as a whole, may vary significantly and at times in ways that are unpredictable by the user, and depends on numerous factors, including: different supply sources, different climatic conditions, season-dependent supply factors, different percentages of inert material, different fuel mixtures, etc.
Consequently, in currently marketed vehicles—in which, as is known, the operating injection time of an injector in each operating state of the engine equals a calibration injection time determined at the initial engine calibration stage using a reference fuel, plus a closed-loop injection time correlated to the composition of the exhaust gases produced by the engine—any alteration in fuel quality may affect the behaviour of the engine in terms of performance and emissions and in direct proportion to the extent to which the fuel used differs from the reference fuel used to calibrate the engine.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an injection control method capable of automatically determining the quality of the fuel used and adapting injection accordingly.
According to the present invention, there is provided a method of controlling injection of an internal combustion engine comprising a number of injectors for injecting fuel for a respective operating injection time in each operating state of the engine, and an oxygen concentration sensor generating a composition signal correlated to the oxygen difference in the exhaust gases with respect to a stoichiometric condition; each of said injectors being assigned, in each operating state of the engine, a respective calibration injection time determined at an initial engine calibration stage using a reference fuel; for a given operating state of said engine, said method being characterized by comprising the steps of:
a) determining a number of operating values of a control parameter as a function of said composition signal and of a proportional-integral control function;
b) determining an intermediate value of said control parameter as a function of said number of operating values of the control parameter;
c) determining a current correction injection time as a function of said intermediate value of said control parameter and of a reference value of the control parameter determined at said initial engine calibration stage using said reference fuel and relative to said operating state of the engine; and
d) determining said operating injection time for said operating state of the engine as a function of a respective said calibration injection time; of a closed-loop injection time depending on said composition signal; and of said current correction injection time.
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Bolla Ugo
Ciasullo Marco
Mauro Marco
Pastorelli Francesco
Santamaria Nelson
C.R.F. Societa Consortile per Azioni
Castro Arnold
Crowell & Moring LLP
Dolinar Andrew M.
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