Abstract: A drive device for a motor vehicle includes an exhaust pipe and a secondary air device having a first secondary air path which feeds into the exhaust gas pipe. Disposed in the first secondary air path is a secondary air pump and a secondary air valve. To compensate, for example, fluctuations in the supply voltage of the secondary air pump, provision is made for arrangement in the secondary air path of a Laval nozzle which can be placed downstream of the secondary air valve.

Abstract: A drive device for a motor vehicle includes an exhaust pipe and a secondary air device having a first secondary air path which feeds into the exhaust gas pip. Disposed in the first secondary air path is a secondary air pump and a secondary air valve. To compensate, for example, fluctuations in the supply voltage of the secondary air pump, provision is made for arrangement in the secondary air path of a Laval nozzle which can be placed downstream of the secondary air valve.

Abstract: The invention relates to a method for checking the function of a tank venting valve between the intake manifold of an internal combustion engine and a fuel tank or a fuel vapor reservoir in which the tank venting valve in operation of the internal combustion engine is opened several times and is closed again after a short opening time and in which during repeated opening and closing the time characteristic of a quantity which is dependent on the opening state of the tank venting valve is recorded. In order to enable a reliable function check of the tank venting valve even in the case of very small and/or time-shifted amplitudes of the quantity to be monitored, it is proposed, according to the invention, that the first derivative of the time characteristic of the quantity be evaluated.

Abstract: The invention relates to a method for testing the mobility of the negative pressure relief valve of the fuel system of a motor vehicle, the negative pressure relief valve depending on the pressure within the fuel system having to be moved between a closed position which closes the fuel system and an open position which clears the fuel system, with the following steps: a) Testing the position of the negative pressure relief valve; and b) Testing the position of the negative pressure relief valve in reaction to a pressure increase within the fuel system if the negative pressure relief valve in step a) was in the closed position. The invention furthermore relates to a system for testing the mobility of the negative pressure relief valve of the fuel system of a motor vehicle.

Abstract: The invention relates to a method for checking the function of a tank venting valve between the intake manifold of an internal combustion engine and a fuel tank or a fuel vapor reservoir in which the tank venting valve in operation of the internal combustion engine is opened several times and is closed again after a short opening time and in which during repeated opening and closing the time characteristic of a quantity which is dependent on the opening state of the tank venting valve is recorded. In order to enable a reliable function check of the tank venting valve even in the case of very small and/or time-shifted amplitudes of the quantity to be monitored, it is proposed, according to the invention, that the first derivative of the time characteristic of the quantity be evaluated.

Abstract: The invention relates to a method for testing the mobility of the negative pressure relief valve of the fuel system of a motor vehicle, the negative pressure relief valve depending on the pressure within the fuel system having to be moved between a closed position which closes the fuel system and an open position which clears the fuel system, with the following steps: a) Testing the position of the negative pressure relief valve; and b) Testing the position of the negative pressure relief valve in reaction to a pressure increase within the fuel system if the negative pressure relief valve in step a) was in the closed position. The invention furthermore relates to a system for testing the mobility of the negative pressure relief valve of the fuel system of a motor vehicle.