Power plants – Internal combustion engine with treatment or handling of... – By means producing a chemical reaction of a component of the...
Utility Patent
1999-07-16
2001-01-02
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
Utility Patent
active
06167697
ABSTRACT:
The present invention relates to an electronic control device for the air/fuel ratio of the mixture supplied to an endothermal engine.
The present invention is advantageously applied in the automobile field, to which the following description will refer without entering into detail.
BACKGROUND OF THE INVENTION
In the automobile field, it is known to use catalytic converters disposed along the exhaust duct for the combusted gases from an endothermal engine in order to remove the polluting substances contained in these gases. It is also known that the maximum efficiency of a catalytic converter, i.e. its ability optimally to remove these polluting substances, requires the air/fuel ratio of the mixture supplied to the engine to be kept close to the stoichiometric value, i.e. within a specific interval including this stoichiometric value.
In order to control the air/fuel ratio, use is made of electronic closed loop control devices in which a first oxygen sensor, disposed along the exhaust duct upstream of the catalytic converter, generates as output a feedback signal V
1
indicating the stoichiometric composition of the exhaust gases and therefore of the air/fuel ratio of the mixture supplied to the engine. These devices supply the feedback signal V
1
to a first control circuit which generates as output a correction parameter KO
2
which is used to modify, in a closed loop, the value of a parameter calculated in an open loop and representative of a quantity of fuel to be injected into the engine cylinders.
These known devices, as a result of the reverse feedback of the signal V
1
, carry out a closed chain control intended to ensure that the air/fuel ratio is caused to oscillate about the stoichiometric value so as to enable the catalytic converter to remove the polluting substances in an optimum way. These devices have, however, certain drawbacks: in the first place they do not make it possible to carry out a diagnosis of the behaviour of the catalytic converter and secondly they are not able to carry out an appropriate control when there are drift errors in the chain including the first oxygen sensor.
In order to overcome these drawbacks, these control devices have been provided with a second oxygen sensor disposed along the exhaust duct downstream of the catalytic converter and a second control circuit connected to this second sensor and to the first control circuit. The second sensor in particular generates as output a feedback signal V
2
indicating the stoichiometric composition of the exhaust gases introduced into the atmosphere, while the second control circuit, which has a proportional branch and an integral branch (P.I.), receives as input the signal V
2
and is adapted to supply a correction signal K
022
to the above-mentioned first control circuit. The correction signal KO
22
is used by the first control circuit to modify the above-mentioned correction parameter KO
22
by recovering the above-mentioned drifts. These devices tend to carry out a control action which maintains the exhaust titre (i.e. the air/fuel ratio measured by the second sensor and standardised to the stoichiometric value) within a predetermined interval of values in order to cause the catalytic converter to work at high efficiency.
Despite the fact that the introduction of the second sensor and the second control circuit has improved the control of the air/fuel ratio and made it possible to carry out diagnoses on the catalytic converter, the above-mentioned control devices have the drawback that they carry out a control action that is slow from the dynamic point of view.
These known devices respond very slowly to any departures of the exhaust titre from the interval of values corresponding to optimum operation of the catalytic converter and therefore require relatively long times to return the exhaust titre within this interval. This is particularly significant in situations immediately following “full load” and “cut-off” conditions, i.e. those conditions following a rapid acceleration or a release of the accelerator pedal.
Following these situations the air/fuel ratio diverges strongly from the stoichiometric value and the catalytic converter does not carry out correct removal of the polluting substances for the whole of the period that the control device requires to bring the exhaust titre back within the above-mentioned interval of values.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a control device for the air/fuel ratio of the mixture supplied to an endothermal engine, which is free from the above-described drawbacks.
The present invention relates to a control device for the air/fuel ratio of the mixture supplied to an endothermal engine of the type described in claim
1
.
The present invention also relates to a method of controlling the air/fuel ratio of the mixture supplied to an endothermal engine.
The present invention further relates to a method for controlling the air/fuel ratio of the mixture supplied to an endothermal engine of the type described in claim
REFERENCES:
patent: 3827237 (1974-08-01), Linder et al.
patent: 5154053 (1992-10-01), Ishida et al.
patent: 5325664 (1994-07-01), Seki et al.
patent: 5335493 (1994-08-01), Uchida et al.
Gaviani Giovanni
Poggio Luca
Secco Marco
Violani Marco
Denion Thomas
Kinberg Robert
Magneti Marelli S.p.A.
Trieu Thai-Ba
Venable
LandOfFree
Device for controlling the air/fuel ratio of the mixture... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for controlling the air/fuel ratio of the mixture..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for controlling the air/fuel ratio of the mixture... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2503254