Patent ID: 11879375
Assignee: PACCAR INC
Field: Environmental technology (Chemistry)
Classification: CPC F  Y | IPC F

Claim 7:
8. A heavy-duty truck, comprising:
a diesel engine;
an exhaust after-treatment system having an upstream end and a downstream end opposite the upstream end, the upstream end coupled to the diesel engine, the exhaust after-treatment system including a selective catalytic reduction system; and
an electronic control unit configured to:
operate the diesel engine such that the diesel engine generates an exhaust gas flow that enters the exhaust after-treatment system;
record a measurement of a level of NOx gases in the exhaust gas flow downstream of the selective catalytic reduction system;
control a diesel exhaust fluid injector upstream of the selective catalytic reduction system to inject diesel exhaust fluid into the exhaust gas flow upstream of the selective catalytic reduction system at an injection rate that is based on the measured level of NOx gases;
adjust the injection rate, thereby changing an ammonia-to-NOx ratio at the selective catalytic reduction system;
record measurements of first levels of NOx gases in the exhaust gas flow upstream of the selective catalytic reduction system and second levels of NOx gases in the exhaust gas flow downstream of the selective catalytic reduction system as the ammonia-to-NOx ratio at the selective catalytic reduction system changes;
determine a measured efficiency of the selective catalytic reduction system based on the measured first and second levels of NOx gases;
determine whether the measured efficiency is positively or negatively correlated with the changing ammonia-to-NOx ratio to determine whether ammonia slip is occurring at the selective catalytic reduction system; and
adjust the injection rate based on whether ammonia slip is occurring at the selective catalytic reduction system.