Robert Boschgmbh

Claus Linsenmaier

Thomas Farr

Elmar Pietsch

Carsten Deringer

A method for detecting a dosing error of a reduction agent in a dosing module of an SCR catalytic converter system. The SCR catalytic converter system comprises the dosing module, which has a dosing valve and a flow valve as well as a delivery module with delivery pump. The SCR catalytic converter system, furthermore, has a return, in which a further flow valve is arranged. Said flow valve changes an effective cross-sectional area of the return. The method herein comprises the following steps: at the beginning, the dosing valve is closed (). At a first pressure value (p) in the system the delivery pump is switched off () and a measurement () of a first pressure rate () of the flow valve of the return subsequently takes place. Additional operation of the pump and the dosing valve occurs and a ratio of pressure rates is determined.

Methods for detecting a dosing error

The invention relates to an expansion body having an equalization chamber, which is separated by an elastic diaphragm from a fluid which flows through part of the expansion body. A mechanical spring applies an additional spring force to the diaphragm, wherein the spring has mechanical prestress. In addition, the invention relates to an SCR system with such an expansion body, and a method for monitoring a pressure sensor in such a SCR system with an expansion body. The method comprises the following steps: first, an anticipated characteristic pressure at which the spring force of the spring of the expansion body is overcome is defined by setting the prestress of the spring in the expansion body.

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Kirchheim unter Teck, Germany

Claus Linsenmaier