US 11,879,375 B2
Exhaust after-treatment in heavy-duty motor vehicles
Cynthia Chaffin Webb, Sedro-Woolley, WA (US); John Lyle Lahti, Anacortes, WA (US); and Charles Wayne Reinhardt Swart, Bellingham, WA (US)
Assigned to PACCAR Inc, Bellevue, WA (US)
Filed by PACCAR Inc, Bellevue, WA (US)
Filed on Jun. 1, 2022, as Appl. No. 17/830,123.
Prior Publication US 2023/0392532 A1, Dec. 7, 2023
Int. Cl. F01N 3/20 (2006.01); F01N 3/08 (2006.01)
CPC F01N 3/208 (2013.01) [F01N 3/0807 (2013.01); F01N 3/0814 (2013.01); F01N 3/0871 (2013.01); F01N 3/0885 (2013.01); F01N 3/206 (2013.01); F01N 3/2006 (2013.01); F01N 3/2066 (2013.01); F01N 2250/12 (2013.01); F01N 2550/03 (2013.01); F01N 2560/026 (2013.01); F01N 2610/02 (2013.01); F01N 2610/146 (2013.01); F01N 2900/04 (2013.01); F01N 2900/0412 (2013.01); F01N 2900/1402 (2013.01); F01N 2900/1614 (2013.01); F01N 2900/1616 (2013.01); F01N 2900/1621 (2013.01); F01N 2900/1622 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A method, comprising:
operating a diesel engine of a heavy-duty truck such that the diesel engine generates an exhaust gas flow that enters an exhaust after-treatment system of the heavy-duty truck, the exhaust after-treatment system including a selective catalytic reduction system;
measuring a level of NOx gases in the exhaust gas flow downstream of the selective catalytic reduction system;
controlling 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;
determining whether ammonia slip is occurring at the selective catalytic reduction system, including:
adjusting the injection rate, thereby changing an ammonia-to-NOx ratio at the selective catalytic reduction system;
measuring 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;
determining a measured efficiency of the selective catalytic reduction system based on the measured first and second levels of NOx gases; and
determining whether the measured efficiency is positively or negatively correlated with the changing ammonia-to-NOx ratio; and
adjusting the injection rate based on whether ammonia slip is occurring at the selective catalytic reduction system.