SCR closed loop control system
AssigneeVolvo Lastvagnar AB
InventorsJohan Dahl, Moataz Ali
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Abstract
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.
Claims6
A method for an exhaust aftertreatment system of an engine comprising at least one selective catalyst reaction (SCR) at least one clean up catalyst downstream from the SCR, an urea injector upstream of the SCR and a first NOx sensor downstream from the clean up catalyst, the method comprising the steps of
- (a) injecting a predetermined amount of urea by the injector,
- (b) providing a second NOx sensor between the SCR and the clean up catalyst
- (c) measuring the NOx content received by the first NOx sensor,
- (d) measuring the NOx content received by the second NOx sensor,
- (e) comparing the first and the second NOx content with each other, and
- (f) reducing the predetermined amount of urea if the first NOx sensor measures a higher NOx content than the second NOx sensor.
A use of the method according to claim for detecting at least one of SCR malfunctioning and poisoning.
Dependencies are inferred from the claim text.