Robert Boschgmbh

Frank Blischke

Eberhard Schnaibel

Erich Schneider

Lothar Raff

Klaus Hirschmann

Georg Mallebrein

Ernst Wild

Lutz Reuschenbach

Konrad Henkelmann

In a method and apparatus for monitoring the operating capability of a catalyzer in the exhaust duct of an internal combustion engine, the operating capability of the catalyzer is assessed on the basis of the increase in temperature produced by the exothermic conversion of the exhaust gases in the catalyzer. The increase in temperature is determined with the aid of two temperature signals, the first temperature signal being produced on the basis of a measurement downstream of the catalyzer and the second temperature signal being formed with the aid of a temperature model. The temperature model may form the temperature downstream of a completely inoperational catalyzer, a catalyzer which is still just sufficiently operational, or a catalyzer which is fully operational. The assessment of the operating capability of the catalyzer is performed on the basis of criteria which are matched to the temperature model used.

Method for monitoring the operating capability of a catalyzer in the

The invention is directed to a method for controlling the composition of the air/fuel mixture for an internal combustion engine. In the method, the mean value of the control oscillation is influenced via a change of the delay times tv with which a sign reversal of the actuating variable change is delayed. The dead time of the control is determined from the time-dependent performance of the control actuating variable and is considered for the change of the delay times tv.

Lambda control method

The invention is directed to a method for interrupting fuel metered to an engine during overrun operation. The engine is equipped with a catalytic converter and the method includes the steps of: determining a criterion for the temperature of the catalytic converter; checking to determine if the criterion satisfies a condition for the temperature of the catalytic converter which is characteristic for a high temperature of the catalytic converter; and, interrupting the metering of fuel to the engine when the condition is not satisfied.

Method for interrupting the metering of fuel during overrun operation of

System for operating a heating element for a ceramic sensor in a motor

A method and a device for forming a simulated signal of the temperature of the exhaust gas, exhaust gas sensor or catalytic converter for an internal combustion engine. Using a temperature characteristic depending on the air mass stream, and two low-pass filters with time constants depending on the air mass stream, the exhaust gas temperature upstream from the catalytic converter, the exhaust gas sensor temperature and the catalytic converter temperature are simulated. The air mass, integrated since the time the internal combustion engine is started, is compared with two threshold values to determine whether or not there is still condensation water present in the exhaust gas channel upstream from the catalytic converter and/or in the catalytic converter itself. If condensation water is present, the simulated temperature(s) is limited to a value of approximately 50.degree. to 60.degree. C. If the entire condensation water in the exhaust gas channel and/or in the catalytic converter was not evaporated during a short run of the internal combustion engine, or if the temperature of the internal combustion engine is extremely low when it is started, then extended times for evaporation of the condensation water are estimated and simulated by increased threshold values for the integrated air mass.

Method and device for forming a simulated signal of the temperature of

A method, including an amplitude evaluation of control oscillations of the oxygen content of the exhaust gas of an internal combustion engine in front of and behind a catalytic converter, for judging the operating condition of the converter in order to determine whether the performance of the catalytic converter has deteriorated past a predetermined point. As soon as this condition is detected using the amplitude evaluation, switching is effected to the frequency evaluation for judging the functioning of the catalytic converter.

Method and apparatus for judging the functioning of a catalytic converter

The invention is directed to a method for reducing the exhaust-gas emissions of an internal combustion engine which is equipped with a lambda control and a catalytic converter and for which the metering of fuel can be interrupted in dependence upon operating parameters. The method is characterized in that the engine at first is operated with a rich fuel/air mixture during transition from operation without fuel metering to operation with fuel metering. The oxygen deficiency associated therewith compensates the oxygen excess which is stored in the catalytic converter when the metering of fuel is interrupted. An operating state wherein oxygen is loaded therefore occurs quickly after a fuel cutoff. This operating state also defines an optimum at steady state and this is advantageous especially for the conversion of nitrogen oxide.

Method for adjusting the fuel/air mixture for an internal combustion

The invention is directed to a method for determining the storage capacity of a catalytic converter of an internal combustion engine with the aid of a first signal from an oxygen-indicating first probe mounted forward of the catalytic converter and a second signal from an oxygen-indicating second probe mounted rearward of the catalytic converter. The first and second signals show the change from rich to lean and vice versa and the method includes the steps of: determining the storage capacity as a quantity proportional to the time-dependent integral of an integration variable; starting the integration at a time point at which said first signal changes from rich to lean or vice versa; and, ending the integration after a time interval. The method does not need a special test operation of the engine to determine the storage capacity of the catalytic converter. Instead, the method can be carried out in any steady-state operating condition for which the probe rearward of the catalytic converter regularly indicates jumps from rich to lean and vice versa. The invention is also directed to an arrangement for carrying out the invention.

Method and arrangement for determining the storage capacity of a

The invention is directed to a method and an arrangement for making an on-board diagnosis of a catalytic converter. For this purpose, the lambda value of the mixture is shifted in a targeted manner and the jump reaction of a signal of a lambda probe arranged rearward of the catalytic converter is utilized in order to detect the amount of mean-value shift for which the successively reduced oxygen-deficiency input quantities or excess input quantities in the catalytic converter drop below the oxygen-storage capability thereof.

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Stuttgart, Germany

Frank Blischke