Power plants – Internal combustion engine with treatment or handling of... – Methods
Reexamination Certificate
1999-02-26
2001-04-03
Walberg, Teresa (Department: 3742)
Power plants
Internal combustion engine with treatment or handling of...
Methods
C060S277000
Reexamination Certificate
active
06209314
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a method for regulating the fuel/air ratio of an internal combustion engine, the output signal from a first lambda probe, which is arranged in the exhaust duct of the internal combustion engine upstream of a catalyst, being supplied to the controller, and the controller emitting a manipulated variable for the fuel/air ratio, and there being supplied to the controller a correcting signal which is obtained from the output signal from a second lambda probe located downstream of the catalyst.
In order to achieve exhaust gases which are as free of pollutants as possible, regulating devices for internal combustion engines are known, in which the oxygen content in the exhaust duct is measured and evaluated. For this purpose, oxygen measuring probes, so-called lambda probes, are known, which operate, for example, on the principle of ionic conduction through a solid electrolyte as a result of an oxygen partial pressure difference and which emit, in accordance with the oxygen partial pressure prevailing in the exhaust gas, a voltage signal which has a voltage jump during the transition from oxygen deficiency to oxygen excess, and vice versa.
The output signal from the lambda probe is evaluated by a controller which, in turn, adjusts the fuel/air mixture via an actuator.
The primary aim of regulating the fuel/air ratio is to reduce harmful components of the exhaust gas emission of internal combustion engines.
With the aid of a second lambda probe, which is arranged downstream of the catalyst, the signal from the first lambda probe is corrected, since the probe is subject to aging phenomena.
Despite this superposed regulation, the aging phenomena of the first lambda probe cannot be corrected sufficiently.
SUMMARY OF THE INVENTION
The object on which the invention is based is, therefore, to specify a method which allows accurate and adaptable regulation, so that the fuel/air ratio is further improved with the effect of a reduction in the exhaust gas emission.
The object is achieved, according to the invention, in that the correcting signal is weighted as a function of the period of the signal from the first lambda probe.
The advantage of the invention is that the controlled system containing the first lambda probe has superposed on it a manipulated variable which is a function of the actually persisting period of the output signal from the first lambda probe, that is to say the actual fault can be compensated.
Advantageously, a weighting factor is determined from the ratio of the actually measured period of the first lambda probe to the period of the first lambda probe during idling.
In a development of the method, the correcting signal is obtained from the comparison of the actually measured output signal from the second lambda probe with a reference value. In this case, the formation of the correcting signal takes place during each changeover of the lambda probe arranged upstream of the catalyst.
At the same time, the correcting signal is advantageously a holding time, by means of which the output signal from the controller is time-shifted, in particular delayed.
A difference is formed from the actually measured output signal from the second lambda probe and the reference value, said difference being integrated in a sign-related manner at the time of changeover of the first oxygen measuring probe, the integrator value being converted into a time.
Advantageously, the desired value corresponds approximately to the average value of the output signal from the second lambda probe during faultfree operation of the first lambda probe.
In order to set the operating point, the time obtained from the signal from the second lambda probe is corrected as a function of the load and rotational speed of the internal combustion engine and is supplied to the controlled system, in which the fuel injection is adapted.
Numerous exemplary embodiments of the invention are possible.
REFERENCES:
patent: 4796425 (1989-01-01), Nagai et al.
patent: 5134847 (1992-08-01), Ogawa et al.
patent: 5255515 (1993-10-01), Blumenstock et al.
patent: 5307625 (1994-05-01), Junginger et al.
patent: 5335538 (1994-08-01), Blischke et al.
patent: 5379591 (1995-01-01), Iwata et al.
patent: 5836153 (1998-11-01), Staufenberg et al.
patent: 5839274 (1998-11-01), Remboski et al.
Patent Abstracts of Japan vol. 007, No. 165 (M-230), Jul. 20, 1983 & JP 58 072647 A (Toyota Jidosha Kogyo KK), Apr. 30, 1983.
Patent Abstracts of Japan vol. 007, No. 133 (M-221), Jun. 10, 1983 & Jp 58 048755 A (Toyota Jidosha Kogyo KK), Mar. 22, 1983.
Farber Martin A.
Mannesmann VDO AG
Van Quang
Walberg Teresa
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