Method and system for verifying the operation of an SCR catalyst
AssigneeGM Global Technology Operations LLC
InventorsStephen Paul Levijoki, Cheryl J Stark, Scott R Gordon, Yue-Yun Wang
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Abstract
A method and control system for a selective catalytic reduction (SCR) catalytic converter and an ammonia dosing module that stores ammonia in a selective catalyst reducing (SCR) catalyst and that depletes the ammonia level by discontinuing or reducing dosing. The control system also includes an SCR conversion efficiency module that determines an SCR efficiency. An SCR efficiency comparison module compares the SCR efficiency to an efficiency threshold and generates a fault indicator when the SCR efficiency is not above the efficiency threshold.
Claims20
A method comprising:
- injecting ammonia, using a dosing injector, into an exhaust stream to store ammonia in a selective catalyst reducing (SCR) catalyst;
- determining whether the stored ammonia is greater than an ammonia threshold;
- reducing an ammonia dosing amount of the SCR catalyst if the stored ammonia is greater than an ammonia threshold;
- waiting a delay period;
- determining, after the delay period, an SCR efficiency if the ammonia dosing amount is reduced;
- determining an efficiency threshold;
- comparing, in response to the ammonia dosing amount being reduced, the SCR efficiency to the efficiency threshold;
- and
- when the SCR efficiency is not above the efficiency threshold, generating a fault indicator in response to the comparing, wherein the efficiency threshold is based on an SCR performance model.
A control system comprising:
- a dosing injector configured to inject ammonia into an exhaust stream;
- a first electronic circuit configured to:
- control the dosing injector to store ammonia in a selective catalyst reducing (SCR) catalyst;
- determine whether the stored ammonia is greater than an ammonia threshold;
- and
- control reducing of an ammonia dosing amount if the first electronic circuit determines the stored ammonia is greater than the ammonia threshold;
- a second electronic circuit configured to wait a delay period and determine, after the delay period, an SCR efficiency if the ammonia dosing amount is reduced;
- and
- a third electronic circuit configured to:
- determine an efficiency threshold;
- perform a comparison, in response to the ammonia dosing amount being reduced, of the SCR efficiency to the efficiency threshold;
- and
- generate a fault indicator in response to the comparison;
- wherein the efficiency threshold is based on an SCR performance model.
Dependencies are inferred from the claim text.