Power plants – Internal combustion engine with treatment or handling of... – Methods
Reexamination Certificate
2000-04-26
2002-01-01
Denion, Thomas (Department: 3748)
Power plants
Internal combustion engine with treatment or handling of...
Methods
C060S285000
Reexamination Certificate
active
06334305
ABSTRACT:
The present invention relates to a self-adapting method of controlling titre in an injection unit for an internal combustion engine.
BACKGROUND OF THE INVENTION
As is known, the majority of vehicles commercially available at present are fitted with injection units provided with systems for controlling titre which are adapted to regulate the quantity of fuel to be supplied to each individual cylinder in order to obtain an exhaust titre which is as close as possible to an objective titre.
Some of these control systems are of the self-adapting type, i.e. they are able to offset the output dispersions that cause the engine and the exhaust unit to move away from the nominal case set at the time of calibration and also partially to offset variations due to the ageing of the components of the engine and the exhaust unit, in particular the oxygen sensors and the catalytic system.
Control systems are known, for instance, which comprise a first and a second oxygen sensor disposed respectively upstream and downstream of the catalytic system. The information supplied by the sensor disposed upstream of the catalytic system is used to calculate a correction coefficient for a theoretical quantity of fuel to be injected into each cylinder such that the titre output from the combustion chamber, upstream of the catalytic system, is equal to an objective titre, while the information supplied by the sensor disposed downstream of the catalytic system is used to apply further corrections to the control parameters calculated on the basis of the information supplied by the sensor upstream of the catalytic system. On the basis of the information from the sensor disposed downstream of the catalytic system, an additional coefficient may in particular be calculated which modifies the value of the objective titre.
These known solutions have, however, a drawback due to the intrinsic slowness of adaptation and do not make it possible to obtain information on the functional nature of the injection control system, in particular on the oxygen sensors, which can be obtained only by using further sensors.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a method which is free from the above-mentioned drawbacks and which, in particular, enables high-speed adaptation.
The invention therefore relates to a self-adapting method of controlling titre for an internal combustion engine
2
provided with a system for reducing pollutant emissions
4
and first and second sensor means of stoichiometric composition
5
disposed respectively upstream and downstream of this system for reducing pollutant emissions
4
and adapted to generate an upstream composition signal V
1
and respectively a downstream composition signal V
2
, this method comprising the stages of:
determining a correction coefficient KO
2
as a function of the upstream composition signal V
1
, the downstream composition signal V
2
and an objective signal V° indicative of an objective exhaust titre;
a) determining an operating quantity of fuel Q
F
to be injected into each cylinder of the engine
2
as a function of the correction coefficient KO
2
;
characterised in that it further comprises the stages of:
b) storing a plurality of current values V
AC
(i, j) of an adaptation signal V
A
, each associated with a respective combination of values of the number of revolutions RPM and the load L of the engine
2
;
c) updating these current values V
AC
(i, j) as a function of this downstream composition signal V
2
;
d) selecting, on each engine cycle, a current value V
AC
(i, j) corresponding to the number of revolutions RPM and the load L of the engine
2
in this engine cycle;
e) generating this adaptation signal V
A
as a function of the current value V
AC
(i, j) selected;
and in that the stage a) comprises the stage of:
al) determining the correction coefficient KO
2
also as a function of this adaptation signal V
A
.
REFERENCES:
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patent: 5361582 (1994-11-01), Uchida et al.
patent: 5598702 (1997-02-01), Uchikawa
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patent: 5901552 (1999-05-01), Schnaibel et al.
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patent: 6003308 (1999-12-01), Tsutsumi et al.
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patent: 6161376 (2000-12-01), Uchikawa
patent: 0596635 (1994-05-01), None
EPO Search Report 00 10 8954 (Aug. 2000) (Partial and Annex Reports).
EPO Search Report 00108954 (09/00) (Including Annex).
Patent Abstracts of Japan; Publication No.: 03151544; Inventor Kashiwanuma Nobuaki; Publication Date: Jun. 27, 2001.
Patent Abstracts of Japan; Publication No.: 04112939; Inventor Furuya Junichi; Publication Date: Apr. 14, 1992.
Poggio Luca
Secco Marco
Denion Thomas
Hall Priddy Myers & Vande Sande
Magneti Marelli S.p.A.
Tran Diem
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