Abstract: A method is provided for operating an internal combustion engine in whose exhaust-gas region an exhaust-gas treatment device is situated, and in which a reagent is introduced into the exhaust-gas region of the internal combustion engine. in addition, a device is provided for implementing the method. The reagent pressure occurring between a reagent safety valve and a reagent dosing valve, disposed directly in the exhaust-gas region is recorded during different states of the reagent safety valve and/or the reagent dosing valve and compared to at least one threshold value. If the threshold is exceeded, a fault signal is provided. This may offer high safety which may be of particular importance when fuel is used as reagent.

Abstract: A method is provided for operating an internal combustion engine in whose exhaust-gas region an exhaust-gas treatment device is situated, and in which a reagent is introduced into the exhaust-gas region of the internal combustion engine. in addition, a device is provided for implementing the method. The reagent pressure occurring between a reagent safety valve and a reagent dosing valve, disposed directly in the exhaust-gas region is recorded during different states of the reagent safety valve and/or the reagent dosing valve and compared to at least one threshold value. If the threshold is exceeded, a fault signal is provided. This may offer high safety which may be of particular importance when fuel is used as reagent.

Abstract: A mixing device for mixing the exhaust gas of an internal combustion engine flowing in an exhaust pipe with a reducing agent as well as an exhaust gas purification system having such a mixing device, in which a mixing body is positionable in the exhaust pipe and which includes a gas impact surface and a spray impact surface so that exhaust gas flowing from the internal combustion engine is able to strike the gas impact surface and reducing agent, which is suppliable transversely to the exhaust gas flow, is able to strike the spray impact surface, the spray impact surface and the gas impact surface forming disjointed sub-areas of the surface of the mixing body. The mixing device distributes the reducing agent uniformly over the cross section of the exhaust pipe and mixes it uniformly with the exhaust gas.

Abstract: A mixing device for mixing the exhaust gas of an internal combustion engine flowing in an exhaust pipe with a reducing agent as well as an exhaust gas purification system having such a mixing device are described. A mixing body that is positionable in the exhaust pipe and having a gas impact surface and a spray impact surface is provided so that exhaust gas flowing from the internal combustion engine is able to strike the gas impact surface and reducing agent, which is suppliable transversely to the exhaust gas flow, is able strike the spray impact surface, the spray impact surface and the gas impact surface forming disjointed sub-areas of the surface of the mixing body. The mixing device distributes the reducing agent uniformly over the cross section of the exhaust pipe and mixes it uniformly with the exhaust gas.

Abstract: A method and a device are proposed for metering a reducing agent, in which means are provided for supplying the reducing agent into a catalytic converter system via a line, for the removal of nitrogen oxides from the exhaust gases, particularly of a Diesel engine, at the end of the line a metering means, especially a metering valve, being situated, and means being provided for regulating the pressure of the reducing agent in the line; the means for regulating the pressure (11, 12, 13; 11, 52, 70; 11, 13, 100) and/or the metering means (7; 120) being able to interact with a pressure recording element (12; 70; 100) which records pressure changes on the output side of the metering means facing away from the line, so that the pressure changes influence the pressure regulation and the metering.