Abstract: An internal combustion engine operated with excess air has an exhaust gas after-treatment device wherein nitrogen oxides in the exhaust gas are reduced by selective catalytic reduction. A pump is connected between a reducing agent container and a metering device for controlled feeding of a reducing agent to the exhaust gas upstream of an SCR catalyst. A pressure accumulator with an associated pressure sensor for intermediately storing the reducing agent is connected between the pump and the metering device. The pump delivers only so much reducing agent into the pressure accumulator as is being used in the exhaust gas after-treatment.

Abstract: Excessive NOx emission in a diesel internal combustion engine with SCR exhaust gas treatment is detected by a control unit. The excessive NOx emission value is determined from the catalytic-converter efficiency calculated for the metering of the reducing agent. In response, measures are taken, such as delayed start of the fuel injection, deactivation of a coasting cutoff, reducing an exhaust gas recirculation rate and/or increasing the idling speed. As a result, the NOx content in the untreated exhaust gas drops, the catalytic-converter temperature increases more quickly after a cold start, and the NOx emission is reduced.

Abstract: A method of driving at least one capacitive actuator with a charge voltage. From a charge quantity .DELTA.Q supplied to the actuator and from the actuator voltage U.sub.p applied to the actuator after the charging operation is terminated, the actuator capacitance is calculated by the equation C.sub.p =.DELTA.Q/U.sub.p. From these values, the energy E.sub.actual =0.5*C.sub.p *U.sub.p.sup.2 =0.5*.DELTA.Q*U.sub.p is calculated. The charge voltage is regulated such that the energy actually supplied is equivalent to a specified desired value.

Abstract: A NO.sub.x reduction system includes an SCR catalytic converter and a metering assembly for reducing agent. A control unit for the reduction system is integrated together with the actuators and sensors as a functional unit at the reducing agent container. This provides savings in terms of lines and plug-in connections, and relieves the burden on the control unit of the internal combustion engine.

Abstract: A method for triggering an electromagnetic consumer with low coil resistance (solenoid for a Diesel injection pump) having a free-running circuit that can be switched over, and an apparatus for performing the method, regulate a voltage at an end stage to a predetermined value. This is accomplished by controlling the control voltage of the end stage during a turn-on phase until a turn-on peak current is reached and then regulating the holding current by repeatedly lowering the current through the end stage and keeping it constant to a predetermined value during a predetermined time period and then raising it again to a maximum value of the holding current until the consumer is turned off.

Abstract: An internal combustion engine, in particular a Diesel engine, includes an injection pump with a filling ramp and a supply ramp of a cam ring, cam disk or cam shaft, pump pistons traveling on the filling and supply ramps, and a magnet valve controlling the injection pump and having a closure defining a supply onset. An apparatus for ascertaining at least one actual operating state of the injection pump includes a structure-borne-sound transducer ascertaining at least one actual operating state.

Abstract: An internal combustion engine has an injection valve. A device for recording an instant at which injection starts in the injection valve includes a differentiating device connected to the injection valve for receiving current through the injection valve and emitting an output signal corresponding to a second derivative of a variation in current with respect to time. A threshold value stage is connected to the differentiating device for receiving the output signal and generating a threshold signal whenever the output signal exceeds a threshold value. A logic device is connected to the threshold value stage for recognizing the instant at which injection starts when the threshold signal occurs for a second time after a triggering instant of the injection valve.