Robert Boschgmbh

Lothar Raff

Eberhard Schnaibel

Klaus Hirschmann

Michael Westerdorf

Hans-Martin Wiedenmann

Erich Junginger

Ernst Wild

Gunther Plapp

Cornelius Peter

Frank Blischke

Claus-Peter Pflieger

Helmut Denz

Helmut Weyl

Klaus D Muller

Franz Rieger

Lutz Reuschenbach

Helmut Maurer

Ferdinand Grob

Werner Mezger

Hermann Dietz

Manfred Homeyer

Eugen Joos

Joachim Heimes

Johannes-Dieter Wichterich

Oliver Hoerrmann

A method and an electronic circuit for regenerating an electrical contact are provided in order to remedy the problem of electrical contacts becoming highly resistive over time. Electrical contacts become highly resistive over time, particularly when the contacts are thermally highly stressed and/or exposed to corrosive gases. To remedy this undesired effect and to reestablish the low resistance of the contacts, an electrical regenerating signal is applied to these contacts.

Method and electronic circuit for regenerating an electrical contact

The invention is directed to a diagnostic arrangement for a potentiometric, electrical exhaust-gas probe for the control of combustion processes with a periodic change of the composition of the combusting air/fuel mixture between oxygen deficiency and oxygen excess. The exhaust-gas probe is heated by an electric heater and outputs a probe signal when the exhaust-gas probe operates without fault which changes between a first region of high signal values (oxygen deficiency) and a second region of low signal values (oxygen excess) with the first region and the second region being separated by a third region of values. A fault announcement is outputted when the probe signal lies within the third region longer than a pregiven longest duration. A fault announcement is also outputted when changes of the current supplied to the electric heater occur within the pregiven longest duration and when the probe signal has temporarily left the third region of values after the change of the heater current.

Diagnostic arrangement for a potentiometric electrically heated exhaust-gas probe for controlling combustion processes

The invention is directed to a method for diagnosing an exhaust-gas probe mounted in the exhaust-gas system of an internal combustion engine for conducting the exhaust gas of the engine. The exhaust-gas probe is mounted downstream of the catalytic converter. The output signal of the exhaust-gas probe is monitored as the output signal changes in response to changes of the concentration of at least one of the components of the exhaust gas. The rate of the change is applied as a criterion as to the state of deterioration of the exhaust-gas probe.

Method and arrangement for diagnosing an exhaust-gas probe

The invention is directed to an arrangement for determining the internal resistance of a lambda probe having a positive pole and an internal resistance. A computer includes at least one computer port having a switchable state, a signal input and fixed pregiven values. A supply voltage source having a positive pole and a measurement resistor are also provided. The positive pole of the supply voltage source is connected to the positive pole of the lambda probe via the computer port and the measurement resistor. An analog/digital converter is connected forward of the signal input and the positive pole of the lambda probe is connected directly to the analog/digital converter for applying variable values to the signal input via the analog/digital converter. The computer is adapted to compute the internal resistance of the lambda probe from the variable values applied to the signal input and the fixed pregiven values. A method of determining the internal resistance of a lambda probe is also disclosed.

Arrangement for determining the internal resistance of a lambda probe

The invention is directed to a method for monitoring the operation of a gas probe, such as a .lambda.-probe for an internal combustion engine. The .lambda.-probe has a probe ceramic (Nernst cell) and a probe heater. The internal resistance (x) of the probe ceramic is measured and a desired value (y) is determined in dependence upon the temperature of the gas to be detected and the heating power of the probe heater. The internal resistance (x) is then compared to the desired value (y) and, when the measured value of the internal resistance (x) exceeds the desired value (y), then a fault signal is generated and/or the fault signal is outputted and/or the fault signal is stored.

Method and arrangement for monitoring the operation of a gas probe

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

A mixture controller for adjusting an output value, which is outputted by a PI two-point controller, to control the air/fuel ratio of a mixture supplied to an internal combustion engine to a pregiven value. The engine produces an exhaust-gas flow during operation and has an oxygen probe mounted in the exhaust-gas flow. The mixture controller continuously detects the signal of the oxygen probe to obtain sequential measurement values of the signal. A check is made as to whether a currently detected measurement value of the signal has crossed over a threshold value in the lean or rich direction compared to the previously detected measurement value of the signal. The output value is changed when a crossover of the signal in the lean direction is present by shifting the output value with a large step via a P-jump in the rich direction and starting an integration of the output value in the rich direction from a previous lean direction. The output value is also changed when a crossover of the signal in the rich direction is present by stopping the integration of the output value in the rich direction and starting an integration in the lean direction after a pregiven delay time has elapsed. The operation of the mixture controller is returned to checking after the output value has changed. A return of the operation of the mixture controller to the checking operation is inhibited until an inhibit time has elapsed.

Mixture controller for an internal combustion engine

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 and an arrangement for monitoring deterioration of lambda probes in the context of a two-probe control. The signal of the lambda probe forward of the converter functions to control the lambda controller and the signal of the lambda probe rearward of the converter influences the lambda controller via an actuating variable and the degree to which the controller is influenced operates for monitoring of the probe forward of the converter. With this method and arrangement, the quality and deterioration of the lambda probe forward of the converter are advantageously detected and, if required, an alarm signal is generated.

Method and arrangement for monitoring a lambda probe in an internal

The invention is directed to a connecting circuit for a potential-free lambda probe having a ground line and a signal line and having an offset voltage source which is connected to the ground line. This offset voltage source raises the potential of the ground line to a pregiven value relative to ground. A ground short is directly detectable in the connecting circuit of the invention in that the potential measured at the signal line drops below the offset voltage. In this way, it is no longer required as in conventional circuits to check for a ground short by enriching the mixture of an engine and to monitor the exhaust gas with the lambda probe.

Connecting circuit for connecting a lambda probe to a control apparatus

The invention is directed to a method for determining the particular current value of at least one control parameter for a lambda control of an internal combustion engine which provides a shift to make the fuel mixture lean or a shift to make the fuel mixture rich in dependence upon the operating state of the controlled engine. The method includes the steps of: determining a base value for the control parameter in dependence upon the current value of at least one pregiven operating variable as the current value applies for a control with a minimal discharge of toxic gas during steady-state operation of the engine; and, modifying the base value with a transition variable having a value decaying as a function of time when changes in the operating state of the engine occur. The method of the invention affords the advantage that the control parameter does not have a value which was applied for a minimum discharge of toxic gas for a typical operation sequence at steady-state or transient operation; instead, for steady-state and transient operations, optimized values are available. In this way, a discharge of exhaust gas is obtained which is lower compared to possibilities which have existed up until now.

Method and arrangement for determining a parameter of a lambda controller

Method and arrangement for determining the internal resistance of a

The invention is directed to a method for checking the aging condition of a catalyzer by utilizing a lambda probe rearward of the catalyzer. For a transition from lean to rich which takes place within a pregiven time span, a check is made if an overshoot of the probe signal occurs which exceeds a pregiven amplitude. A conclusion is drawn as to the aging condition of the catalyzer from an overshoot when the latter occurs. Transitions between lean and rich and vice versa take place especially during the transition from overrun operation to controlled operation of the engine. Transitions of this kind have large swings of the signals of the lambda probes and this permits reliable measurements. In contrast, conventional methods operate exclusively when the engine to which the catalyzer belongs is lambda controlled. The relatively small signal amplitudes occurring thereby lead to a signal/noise ratio which is considerably poorer than in the methods according to the invention.

Method and arrangement for checking the aging condition of a catalyzer

Method and arrangement for lambda control

The invention relates to a method for the continuous lambda control of an internal combustion engine 13 having a catalyzer. The method is carried out by generating a control oscillation FS of pregiven amplitude at least in pregiven operating conditions. This method is based on the recognition that with an increase in amplitude of the control oscillation, the conversion window becomes wider insofar as a maximum amplitude is not exceeded. The conversion window is that range of lambda values wherein the conversion exhibits at least a pregiven quality.

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Remseck, Germany

Lothar Raff