Abstract: A method for regulating the fuel/air ratio of a combustion process which is operated alternatingly with excess air and air deficiency, and having at least one catalyst volume in the exhaust gas of the combustion process which stores oxygen when there is excess oxygen in the exhaust gas and gives it off when there is oxygen deficiency, in which method the oxygen charges into the catalyst volume taking place when there is excess air, and the oxygen discharges from the catalyst volume taking place when there is air deficiency determined, and in which the fuel/air ratio is regulated in a first control loop such that the sum of the oxygen charges and oxygen discharges determined in a predefined interval takes on a predetermined value, wherein the combustion process is operated using oxygen excess or oxygen deficiency, respectively, at least until these appear at an oxygen-sensitive Nernst probe downstream from the catalyst volume.

Abstract: An internal combustion engine (1), in particular for a motor vehicle, is described; it is equipped with a catalytic converter (12) which may be exposed to nitrogen oxides. A lambda probe (13) is provided for measuring the oxygen concentration downstream from the catalytic converter (12). The nitrogen oxides supplied to the catalytic converter (12) are increased by a controller (18), and the conversion capacity of the catalytic converter (12) is concluded from the increase in oxygen concentration downstream from the catalytic converter (12).

Abstract: A method of heating a main catalytic converter positioned downstream from at least one primary catalytic converter by supplying unburned fuel generated by the engine in the exhaust gas upstream from the main catalytic converter while at the same time surplus air is present upstream from the main catalytic converter, where the generation of unburned fuel by the engine takes place at a separate time and/or place from the generation of surplus air in the exhaust gas by the engine.

Abstract: An internal combustion engine (1), especially for a motor vehicle, is described, which has a three-way catalytic converter (12″) and a storage catalytic converter (12′) which can be loaded with and unloaded of nitrogen oxides. A diagnosis of the storage catalytic converter (12′) is carried out by a control apparatus (18) below a temperature at which the three-way catalytic converter (12″) does not yet operate.

Abstract: An internal combustion engine (1), especially for a motor vehicle, is described, which has a catalytic converter (12) which can be loaded with and unloaded of nitrogen oxides. An NOx sensor (14) is provided with which NOx emissions can be measured downstream of the catalytic converter (12). The catalytic converter (12) can be only partially loaded by a control apparatus (18). An increased NOx emission can be generated forward of or in the catalytic converter (12) by the control apparatus (18). A conclusion can be drawn as to the operability of the catalytic converter (12) by the control apparatus (18) from NOx emissions measured downstream.

Abstract: An internal combustion engine (1), especially for a motor vehicle, is described, which has a catalytic converter (12) which can be loaded with and unloaded of nitrogen oxides. An NOx sensor (14) is provided with which NOx emissions can be measured downstream of the catalytic converter (12). The catalytic converter (12) can be only partially loaded by a control apparatus (18). An increased NOx emission can be generated forward of or in the catalytic converter (12) by the control apparatus (18). A conclusion can be drawn as to the operability of the catalytic converter (12) by the control apparatus (18) from NOx emissions measured downstream.

Abstract: An electrochemical sensor for ascertaining a gas concentration of a measuring gas includes an electrochemical element, including a first solid electrolyte body having an electrochemical pump cell and a first and a second electrode, and having a gas compartment which is connected via a gas access opening to the measuring-gas compartment, and in which one of the two electrodes is arranged. The electrochemical element further includes a second solid electrolyte body having an electrochemical sensor cell (Nernst cell) and a third and a fourth electrode. The surface of the first solid electrolyte body faces the measuring-gas compartment, and the gas access opening is covered by a porous protective layer. The electrochemical sensor includes a layer that exhibits a higher density or a lower porosity compared to the protective layer and that is allocated to the porous protective layer.

Abstract: An electrochemical sensor for ascertaining a gas concentration of a measuring gas includes an electrochemical element, including a first solid electrolyte body having an electrochemical pump cell and a first and a second electrode, and having a gas compartment which is connected via a gas access opening to the measuring-gas compartment, and in which one of the two electrodes is arranged. The electrochemical element further includes a second solid electrolyte body having an electrochemical sensor cell (Nernst cell) and a third and a fourth electrode. The surface of the first solid electrolyte body faces the measuring-gas compartment, and the gas access opening is covered by a porous protective layer. The electrochemical sensor includes a layer that exhibits a higher density or a lower porosity compared to the protective layer and that is allocated to the porous protective layer.

Abstract: A method is presented for controlling the supply of reducing agent to a NOx-storage catalytic converter of an internal combustion engine, which is operated at least at times with a lean air/fuel mixture, with an exhaust-gas sensor mounted in flow direction rearward of the NOx-storage catalytic converter; wherein the supply of the reducing agent takes place repeatedly in time intervals separate from each other; and wherein the reducing agent quantity, which is supplied in each time interval, is reduced compared to that quantity which is supplied in a previous supply phase in which a reaction of the exhaust-gas sensor occurred.

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 and an arrangement for diagnosing a catalytic converter arranged in the exhaust-gas system of an internal combustion engine. The catalytic converter is configured to have an oxygen storage capability and a nitrogen oxide storage capability. A first exhaust-gas probe is mounted rearward of the catalytic converter and a second exhaust-gas probe is mounted forward thereof. The oxygen concentration of the exhaust gas forward of the catalytic converter is alternately increased and decreased so that the signals of both exhaust-gas probes change. A first phase shift between the signals of both exhaust-gas probes is detected when the oxygen concentration increases and a second phase shift between the signals is detected when the oxygen concentration decreases. The difference of the phase shifts is determined and a fault signal is outputted and/or stored when this difference does not reach a pregiven threshold.

Abstract: The invention is directed to diagnosing a catalytic converter capable of storing nitrogen oxides and mounted in the exhaust-gas system of an internal combustion engine. A signal-emitting exhaust-gas probe is provided rearward of the catalytic converter and the exhaust gas forward of the catalytic converter is influenced by increasing components in the exhaust gas which are effective as a reducer thereby triggering a change of the signal. The time elapsed between the start of the influencing and the change of the signal is evaluated to diagnose the catalytic converter.

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 a method for checking the operability of a tank-venting system. The tank-venting system includes a tank, an adsorption filter having a tank-venting line, a connecting line for connecting the adsorption filter to the tank, a tank-venting valve and a valve line connecting the adsorption filter to the tank-venting valve. A pressure source is provided for introducing a pressure into the tank-venting system, an operating characteristic variable of the pressure source is detected only over a pregiven time interval (.DELTA.t.sub.m) when introducing the pressure to obtain a time-dependent trace of the operating characteristic variable. The time-dependent trace is extrapolated and a conclusion is drawn as to the presence of a leak therefrom.

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: A device for lowering boost pressure as a function of a defined setpoint engine torque (MMS) when the setpoint engine torque (MMS) or a setpoint engine performance quantity associated therewith is smaller than a corresponding engine performance quantity (MMFA) that is specified without boost pressure intervention. Thus, all performance quantities which require a specific engine torque are able to be controlled in open or closed loop by lowering boost pressure.

Abstract: The invention is directed to a method for adjusting the air/fuel ratio for an internal combustion engine having a catalytic converter connected downstream thereof which is capable of storing oxygen. In this method, the oxygen components in the exhaust gas of the engine are detected upstream of the catalytic converter and downstream thereof and the adjustment of the fuel/air ratio is influenced. In the method, a measure for the instantaneous oxygen fill level of the catalytic converter is determined from the above-mentioned oxygen components with the aid of a model. Data as to the state of deterioration of the catalytic converter are derived from the model parameters. The air/fuel ratio is so adjusted that the oxygen fill level of the catalytic converter is held to a constant mean level.

Abstract: The invention is directed to a method and arrangement for checking the operability of a vessel. Pressure is introduced into the vessel utilizing a pressure source having operating variables which vary during operation of the pressure source. These operating variables are detected while the pressure is introduced into the vessel and a conclusion as to a presence of a leak in the vessel is drawn from the operating variables. By utilizing the operating variables, a statement as precise as possible is provided as to the presence of the leak with as little additional equipment as possible.

Abstract: 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.