Internal-combustion engines – Charge forming device – Including exhaust gas condition responsive means
Reexamination Certificate
1999-07-16
2001-05-01
Kwon, John (Department: 3747)
Internal-combustion engines
Charge forming device
Including exhaust gas condition responsive means
C123S696000
Reexamination Certificate
active
06223735
ABSTRACT:
The present invention relates to a method of control of an oxygen linear sensor.
In particular the present invention relates to a control method for an oxygen linear sensor known as “UEGO” sensor (universal exhaust gas oxygen ensor), to which explicit reference is made hereinafter though without loss of its general nature.
BACKGROUND OF THE INVENTION
The present invention is of advantage in the automotive field, where it is known to use a UEGO sensor, located along the exhaust duct of an internal combustion engine, to obtain information concerning the composition of the exhaust gases.
The UEGO sensor has two electrolytic cells responding to oxygen ions, and a diffusion chamber interposed between the actual cells and able to receive part of the combustion gases at the outlet from the engine. In addition, the UEGO sensor provides for the use of a test arrangement which is connected to the sensor itself by means of a connector, and is able to pilot, that is control, electrically one of two electrolytic cells to ensure a control action on the sensor. In particular the control means is designed to originate an oxygen ion drainage mechanism from the diffusion chamber to atmosphere and vice versa, in order to obtain within the chamber an exhaust gas composition equal to that which would be obtained in the event of the air/petrol ratio of the mixture fed to the engine becoming stoichiometric, i.e. equal to 14.57.
The intensity of the test action, that is to say the intensity of the control current required to maintain the stoichiometric level within the diffusion chamber, is the information on the basis whereof the test arrangement generates a Vout signal representative of the composition of the exhaust gases proceeding from the engine.
At present the aforesaid control arrangement, before installation on the vehicle, needs to be connected to a compensation resistance able to compensate eventual spreads of variations control current to ensure that the Vout signal is truly representative of the composition of engine exhaust gases. In effect, in the absence of a compensation resistance, the Vout signal would not be effectively representative of the percentage of oxygen in the exhaust gases owing to the swing in control current from the theoretical value due to inevitable losses in the control arrangement. The said compensation resistance, of which the nominal value is indicated by the sensor manufacturer for production purposes, is inserted between two connections of the said connector, and cooperating with the control arrangement, intervenes actively in the generation of the Vout signal recovering the losses in control current.
However, the compensation resistance, in addition to representing an additional cost and involving the installation operations, is subjected to strong thermal stress during the operation of the engine in that it is located in the engine compartment. Consequently, on varying the temperature of the engine it occurs that the compensation resistance assumes differing values in relation to the nominal value which ensures a correct compensation. This involves the control current spreads not being compensated adequately and the Vout signal not being effectively indicative of the true oxygen percentage in the exhaust gases and, consequently, of the effective rating of the mixture.
SUMMARY OF THE INVENTION
The purpose of the present invention is to provide a control method for an oxygen linear sensor which will allow the aforementioned disadvantage to be removed, or that will allow the generation of a Vout signal which is effectively indicative of the quantity of oxygen of present in the exhaust gases, without the use of the compensation resistance.
According to the present invention there is provided a method for controlling an oxygen linear sensor arrangement including an oxygen linear sensor located along an exhaust duct of an internal combustion engine, the sensor having at least a first electrolytic cell, a second electrolytic cell and a diffusion chamber receiving an exhaust gas flowing in the exhaust duct, the sensor supplying a first signal correlated to a difference between a composition of the exhaust gas within the diffusion chamber and a reference stoichiometric composition, the method including the steps of: sensing the first signal; supplying a controlled current, as a function of the first signal, to the sensor to activate oxygen ions draining between the diffusion chamber, the first electrolytic cell and the second electrolytic cell, in a manner to vary the composition of the gas within the diffusion chamber for canceling the difference between the composition of the exhaust gas within the diffusion chamber and the reference stoichiometric composition; using the controlled current to generate a first output signal correlated to an oxygen content of the exhaust gas; supplying a controlled gas to the sensor, the controlled gas having a controlled composition; recording a behavior of the first output signal during an interval of time in which the sensor is surrounded by the controlled gas; averaging the first output signal during the timed interval to obtain a mean value; calculating a correction parameter on the basis on the mean value and of a nominal value representing a theoretical value of a first output signal in the presence of the controlled gas; and correcting the first output signal by using the correction parameter to produce a corrected output signal proportional to the exhaust gas oxygen content.
REFERENCES:
patent: 4723521 (1988-02-01), Mieno et al.
patent: 4796587 (1989-01-01), Nakajima et al.
patent: 4922429 (1990-05-01), Nakajima et al.
patent: 4939658 (1990-07-01), Sekozawa et al.
patent: 5199409 (1993-04-01), Miyashita et al.
patent: 5524472 (1996-06-01), Hötzel
patent: 5558752 (1996-09-01), Wang et al.
patent: 5580440 (1996-12-01), Ueno et al.
Ceccarini Daniele
Poggio Luca
Secco Marco
Kinberg Robert
Kwon John
Magneti Marelli S.p.A.
Spencer George H.
Venable
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