Importance

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Abstract

A method for controlling the temperature of an exhaust gas treatment system in the exhaust system of an internal combustion engine in the region of a predetermined intended temperature, comprising a two-position device for varying the temperature of the exhaust gases, a device for measuring the actual temperature and a device for determining a quantity which approximately represents a value for the input of energy into the exhaust gas treatment system is described, as is an apparatus for putting the method into practice. The actual temperature is compared with the intended temperature in a two-step control element and an output signal is produced. From this output signal a modified output signal is produced and supplied to the varying device, such that in case of an output signal which indicates heating of the exhaust gas, if the energy input value is increasing this signal is modified in a direction effecting cooling of the exhaust gas, and/or that in the case of an output signal which indicates cooling of the exhaust gas, if the energy input value is decreasing this signal is modified in a direction effecting heating of the exhaust gas. Further, the two-step control can be formed so as to have accelerated response. By these measures a stable temperature control is obtained despite large time lags.

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