Abstract: A process and system are provided for automatically controlling the fraction of the exhaust gas quantity returned to an internal-combustion engine with respect to the mixture quantity fed on the whole to the internal-combustion engine, which mixture quantity is formed by the returned exhaust gas quantity and a fresh air quantity. The actual fraction of the returned exhaust gas quantity with respect to the mixture quantity fed on the whole to the internal-combustion engine is determined by sensors from measurements of the temperature of the fed fresh air quantity, the temperature of the returned exhaust gas quantity and the temperature of the mixture quantity fed as a whole. This actual fraction of the returned exhaust gas quantity is adapted to a predetermined desired fraction.

Abstract: An internal combustion engine having a turbocharger with variable turbine geometry includes a compressor and an exhaust-gas turbine, whose turbine geometry can be adjusted to adjustably set the effective turbine cross section area. Using a closed-loop and open-loop control device, the operating state of the internal combustion engine can be detected, and the internal combustion engine can be adjusted as a function of the load and state. A movable limit stop is provided for limiting the control path of the variable turbine geometry, the limit stop being adjustable between a limiting position that limits the control path of the variable turbine geometry and a release position outside of the control path of the turbine geometry.

Abstract: A process and system are provided for automatically controlling the fraction of the exhaust gas quantity returned to an internal-combustion engine with respect to the mixture quantity fed on the whole to the internal-combustion engine. The mixture quantity is formed by the returned exhaust gas quantity and a fresh air quantity. The actual fraction with respect to the mixture quantity fed on the whole is determined by sensors measuring a plurality of operating parameters selected from the temperature of the fed fresh air quantity, the temperature of the returned exhaust gas quantity, the temperature of the mixture quantity fed as a whole, the temperature of the exhaust gas flowing out of the internal-combustion engine, the flow rate of the fresh air quantity fed to the internal-combustion engine, and the flow rate of the mixture quantity fed on the whole to the internal-combustion engine. This actual fraction of the returned exhaust gas quantity is adapted to a predetermined desired fraction.

Abstract: In an exhaust gas recirculation arrangement comprising a housing forming a passage for an exhaust gas flow of an internal combustion engine and having a valve seat with a valve disc movably supported in the housing on a valve stem so as to be seated on the valve seat for closing the valve but being movable therefrom against the flow direction of the exhaust gas for opening the valve, a flow guide member is disposed in the valve housing upstream of the valve disc in such a way that, in its open position, the valve disc abuts the guide member and the guide member conducts the exhaust gas past the valve disc.

Abstract: In an internal combustion engine with exhaust gas re-circulation including a fresh air supply duct extending from the charger of a turbocharger to the engine, an exhaust pipe extending from the engine to the turbine of the turbocharger for driving the turbocharger, and an exhaust gas re-circulation pipe extending from the exhaust pipe to the intake duct, the exhaust gas re-circulation pipe includes a flap valve having a pivotally supported flap which, in an open position of the flap valve, is disposed in a plane parallel to the direction of the exhaust gas flow through the flap valve for minimizing the flow resistance in the exhaust gas re-circulation pipe.