Volvo Lastvagnar Ab

Mack Trucks, Inc.

Moataz Ali

Kenth I Svensson

Johan Dahl

A method for an exhaust after treatment system of an engine including at least one selective catalyst reaction (SCR), at least one clean up catalyst downstream from the SCR, a urea injector upstream of the SCR and a first NOx sensor downstream the clean up catalyst. The method includes the steps of injecting a predetermined amount of urea by the injector, providing a second NOx sensor between the SCR and the clean up catalyst, measuring the NOx content received by the first NOx sensor, measuring the NOx content received by the second NOx sensor, comparing the first and the second NOx content with each other, and reducing the predetermined amount of urea if the first NOx sensor measures a higher NOx content than the second NOx sensor.

SCR closed loop control system

An apparatus for treating engine exhaust gas includes comprising an exhaust conduit for leading exhaust gases from an engine to an outlet, a particulate filter connected in the exhaust conduit to receive exhaust gas, a heat source connected in the exhaust conduit upstream of the particulate filter, and, a heat exchanger connected to receive exhaust gas exiting the particulate filter and arranged to heat a portion of the exhaust conduit upstream of the heat source and particulate filter. Heating the exhaust gases prior to entry into the particulate filter helps ensure oxidation of the trapped particulate matter.

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Göteborg, Sweden

Moataz Ali