Robert Boschgmbh

Max-planck-gesellschaft Zur F&#xf6;rderung Der Wissenschaften E. V.

Gerhard Hotzel

Harald Neumann

Johann Riegel

Walter Strassner

Werner Weppner

Gerhard-Ludwig Schlechtriemen

The invention is directed to an arrangement for detecting the oxygen content in the exhaust gas of an internal combustion engine. The arrangement includes a concentration measuring cell operating pursuant to the Nernst principle. The concentration measuring cell has a measuring electrode, a solid electrolyte and a reference electrode and a series circuit which includes a direct voltage source and a series resistor. The series circuit connects the measuring electrode to the reference electrode. The measuring electrode communicates with the exhaust gas of the internal combustion engine and is connected to the reference electrode via the solid electrolyte. The reference electrode communicates with the reference gas volume. The reference gas volume is partitioned from the exhaust gas and from the ambient air so that a particle exchange between the reference gas volume and the exhaust gas as well as between the reference gas volume and the ambient air is at least made more difficult. The output voltage of the concentration measuring cell defines a measure for the difference of the oxygen concentrations in the exhaust gas of the engine and the reference gas volume. The output voltage of the direct voltage source and/or the value of the series resistance is so pregiven that an electric current Ip is always so directed that oxygen is transported from the exhaust gas to the reference gas volume independently of the output voltage of the concentration measuring cell. The current Ip flows in a current circuit including direct voltage source, series resistance and concentration measuring cell.

Arrangement for detecting the oxygen content in the exhaust gas of an

The invention is directed to an evaluating arrangement 10 for the probe signal of a heated amperometric oxygen probe 11 which is mounted in the flow of the exhaust gas from an internal combustion engine 13. The heater unit 18 of the probe is continuously operated with such a heater voltage that the internal resistance of the prove remains constant. However, for this reason, an ever increasing probe temperature (that is, an however, leads to an unwanted increase of the probe signal and this increase must be compensated. For this compensation, the realization is utilized that the increase of the probe temperature is clearly connected to the increase of the heater voltage. The amount of the increase of the heater voltage is determined by comparison measurements in a calibration operating state of the engine. A corrective value is formed from the detected change of the heater voltage and is mathematically coupled to the measurement signal in order to obtain a corrected measurement signal which exhibits neither temperature-caused errors nor deterioration-caused errors.

Evaluating arrangement for the signal of an oxygen probe

The invention is directed to a method of operating an exhaust-gas probe having a pumped reference atmosphere in a relatively closed volume. In this method, the oxygen ion current, which carries the pump current Ip to the reference atmosphere, is temporarily increased under specific conditions. In this way, an adulteration of the reference atmosphere can be more rapidly eliminated. This adulteration can occur because of fuel particles which diffuse in.

Method of operating an oxygen probe having an internal reference

An arrangement determines a voltage which indicates the lambda value of an air/fuel mixture supplied to a combustion engine generating exhaust gas during the operation thereof. The arrangement includes a two-cell oxygen probe mounted in the exhaust gas flow of the engine. The two-cell oxygen probe has an exhaust-gas space for the exhaust gas and an ambient-air space for ambient air. The oxygen probe has a pump cell having two electrodes and a sensing cell having two electrodes. A switchover stage outputs a voltage indicating the electric pump current through the pump cell when a control to the lambda value deviating from one is to be made and outputs that Nernst voltage which is taken off between the electrodes of the sensing cell facing into the ambient air and one of the remaining ones of the electrodes when a control to the lambda value one is to be made. For controlling to the lambda value one, the Nernst voltage supplies a significantly more precise signal than the voltage derived from the pump current.

Arrangement for determining the lambda value of an air/fuel mixture

A solid state cell for measuring the activity of a component of a mixture using a solid ionic conductor, which is in contact on one side with a reference phase and on the other side with a phase sensitive to the gas component to be determined, is to be improved in such a manner that its detection sensitivity and measuring stability are increased. For this purpose, the gas sensitive phase contains an addition of a substance that increases the electronic conductivity and does not chemically react with the components of the sensitive phase and the gas to be determined.

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Stuttgart, Germany

Gerhard Hotzel