Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
1999-07-16
2001-05-15
Warden, Sr., Robert J. (Department: 1744)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S406000, C204S408000, C123S693000, C123S694000
Reexamination Certificate
active
06231735
ABSTRACT:
The present invention relates to an oxygen linear sensor test arrangement.
BACKGROUND OF THE INVENTION
In particular the present invention relates to the oxygen linear sensor test arrangement known as the “UEGO” sensor (universal exhaust gas oxygen sensor), to which the following makes explicit reference though without loss of its general nature.
The present invention is of advantage in the automotive field, where it is known to use a UEGO sensor, located along the exhaust manifold 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 placed 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 control electrically the electrolytic cells to produce a test action on the sensor itself. In particular such control means is designed to provide an oxygen ion draining mechanism from the diffusion chamber to atmosphere and vice versa, in order to obtain within the actual chamber an exhaust gas composition equal to that which would obtain 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 pumping current required to maintain the stoichiometric level within the diffusion chamber, is the information on the basis whereof the test arrangement generates the Vout output signal representative of the composition of the exhaust gases proceeding from the engine. The Vout signal is proportional to the quantity of oxygen present within the exhaust gas and consequently, is indicative of the air stroke/petrol ratio of the mixture fed to the engine.
Presently the test arrangements, before installation on the vehicle, need to be connected to a compensation resistance to compensate for eventual spreads (variation) of the pumping current.
The compensation resistance, the nominal value whereof is shown by the sensor manufacturer on completion of production, is inserted between two connections of the said connector, and cooperating with the test arrangement, actively intervenes in the generation of the Vout signal. Unfortunately the compensation resistance, being located within the engine space, is subject to heavy thermal stresses during operation of the engine.
In consequence, on variation of the engine temperature it occurs that the compensation resistance assumes differing values in relation to the nominal value which would ensure a correct compensation. This means that the variation in pumping currents are not adequately compensated and that the control arrangement provides a Vout output signal which is not effectively indicative of the composition of the exhaust gases.
SUMMARY OF THE INVENTION
The purpose of the present invention is to achieve an oxygen linear sensor test arrangement, which provides a solution to the aforesaid problem. According to the present invention there is provided a control arrangement for an electrically controllable, linear oxygen sensor located along an exhaust manifold of an internal combustion engine and having a diffusion chamber for receiving part of the combustion gases of the internal combustion engine, the sensor having an output for supplying a first signal correlated with a difference between a composition of the combustion gases inside the chamber and a reference stoichiometric composition, the control arrangement comprising: a feedback control circuit having an input for receiving the first signal and for supplying a pumping current to the sensor to initiate an oxygen ion draining mechanism from and/or to the diffusion chamber for obtaining the reference stoichiometric composition inside the diffusion chamber; an output circuit for sensing the pumping current and for supplying a second signal in dependence of the pumping current correlated with a quantity of oxygen present in the combustion gases entering the diffusion chamber; a compensation resistance for compensating spreads of the pumping current between individual sensors: an acquisition circuit connected to the compensation resistance for producing a compensation parameter representative of the compensation resistance, the acquisition circuit comprising voltage supply means for supplying a reference voltage present at a first terminal of the compensation resistance, a voltage divider connected to a second terminal of the compensation resistance and having an output terminal supplying a voltage signal correlated with the compensation resistance, first and second analog to digital conversion means each having an input connected to a respective one of the voltage supplying means and the second terminal of said compensation resistance, calculation means having input terminals connected to respective output terminals of the first and second analog to digital conversion means for calculating and outputting the compensation parameter; storage means for storing the compensation parameter; and a correction circuit having inputs for receiving the compensation parameter and the second signal and having an output terminal supplying an output voltage correlated with the compensation parameter and with the second signal.
REFERENCES:
patent: 4532013 (1985-07-01), Dietz et al.
patent: 4796587 (1989-01-01), Nakajima et al.
patent: 4981125 (1991-01-01), Kato et al.
patent: 5130002 (1992-07-01), Murase et al.
patent: 5366610 (1994-11-01), Hirako et al.
patent: 5524472 (1996-06-01), Hötzel
patent: 5558752 (1996-09-01), Wang et al.
Patent Abstracts of Japan, 58-162858, Dec. 24, 1983.
Ceccarini Daniele
Poggio Luca
Rinaudo Chiaffredo
Secco Marco
Kinberg Robert
Magneti Marelli S.p.A.
Olsen Kaj K.
Spencer George H.
Venable
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