Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: The internal resistance of a lambda probe is determined by: the application of a clocked direct-current counter voltage to the probe via a series resistor; the measurement of the output voltages with the counter voltage connected and disconnected; and, the calculation of the internal resistance from the measured values and known resistance values.Apart from the components of a conventional arrangement, this method requires only a series resistor and a switch for implementation. Measurement can be carried out at short time intervals without excessively high direct-current voltage loading which affects the service life.The internal resistance measured is compared with a desired resistance and the control deviation determined in this way is used to determine the duty factor for probe heating clocked with fixed frequency.

Abstract: 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.

Abstract: An arrangement for lambda control operates on an internal combustion engine (11) comprising a catalytic converter (12) and a lambda probe (13.v) mounted in front of the catalytic converter and a lambda probe (13.h) mounted behind the catalytic converter. The arrangement integrates by means of an integration means (15) the difference between the actual lambda value measured by the rear probe and the lambda desired value to which controlling is to be effected. The integration value is used as control desired value for a means (16) for lambda control. This arrangement and the associated method make it possible to control to the actually wanted lambda desired value even if the front lambda probe carries out incorrect measurements, for example because of hydrocarbons in the exhaust gas in front of the catalytic converter or, in the case of continuous-action control, faulty linearization of the probe characteristic.

Abstract: 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.

Abstract: The invention is directed to a method for lambda control of an internal combustion engine having a catalyzer and a measuring probe arrangement in front of the catalyzer for emitting a measuring signal and a testing probe arrangement behind the catalyzer for emitting a test signal. The method includes the steps of: forming a ratio between the measuring signal and the test signal at pregiven operating conditions; evaluating said ratio as an estimating quantity for the conversion rate of the catalyzer; and, modifying output values of control parameters in a pregiven controlled manner on the basis of the instantaneous values of said ratio, said output values being applicable for controlling an internal combustion engine having a new catalyzer. This method affords the advantage that it evaluates a catalyzer with the aid of the above-mentioned ratio value and controllably modifies values of control parameters in dependence upon the evaluation ratio.

Abstract: The invention is directed to a method for the temperature open-loop control and closed-loop control of exhaust gas probes for mixture control systems having several heatable exhaust gas probes. For this purpose, the temperature of one exhaust gas probe is closed-loop controlled in a control loop and the heaters of other exhaust gas probes are open-loop controlled. The closed-loop controlled exhaust gas probe controls the open-loop controlled exhaust gas probes insofar as the actuating variable of the temperature control loop is used as the output value for the temperature open-loop control of the other exhaust gas probes.

Abstract: In a method for lambda value detection, the voltages of the loaded and the unloaded lambda sensor are detected and the internal resistance of the sensor is calculated from these values with the aid of the known value of the load resistance. The value of the internal resistance and the respective value of the voltage of the sensor in the unloaded state serve as input variables for a characteristic field, in which lambda values dependent on values of the internal resistance and of the voltage of the sensor in the unloaded state are stored. The method of the invention affords the advantage that lambda values can be measured very accurately even in the strongly temperature-dependent rich branch of a sensor, for example, of a sensor of the Nernst type. The values thus detected can be indicated by a measuring device or they can be used for exhaust gas control, for example in warming-up or at full load.

Abstract: A control system for controlling the air/fuel ratio in an internal combustion engine 10, in which an oxygen probe (lambda probe) 13 is arranged in the exhaust gas of the internal combustion engine 10, has a control device 12 for continuous control. The actual value of the air ratio lambda is determined via a measured probe output voltage in conjunction with an at least approximately predetermined probe-characteristic relationship 16 between the value of the probe output voltage and the value of the air ratio lambda associated therewith. After forming the difference of desired value and actual value of the air ratio lambda, the air/fuel ratio is controlled on the basis of this difference. Such a control system is used primarily in order to reduce the total emission of the main pollutant components of the exhaust gas of an internal combustion engine.