US 11,725,555 B1
Aftertreatment system
Joshua L. Ratts, East Peoria, IL (US); Hrishi Lalit Shah, Dunlap, IL (US); Tyler V. Richards, Parker, CO (US); Matthew Colin Mowers, Peoria, IL (US); and Sowmya Nagesh, Peoria, IL (US)
Assigned to Caterpillar Inc., Peoria, IL (US)
Filed by Caterpillar Inc., Peoria, IL (US)
Filed on Feb. 7, 2022, as Appl. No. 17/665,796.
Int. Cl. F01N 3/029 (2006.01); F01N 3/20 (2006.01); B01D 53/94 (2006.01)
CPC F01N 3/0293 (2013.01) [B01D 53/9418 (2013.01); B01D 53/9431 (2013.01); B01D 53/9495 (2013.01); F01N 3/208 (2013.01); F01N 3/206 (2013.01); F01N 3/2066 (2013.01); F01N 2560/026 (2013.01); F01N 2610/1453 (2013.01); F01N 2900/1402 (2013.01); F01N 2900/1411 (2013.01); F01N 2900/1602 (2013.01); F01N 2900/1606 (2013.01); F01N 2900/1621 (2013.01); F01N 2900/1622 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An aftertreatment system for a diesel engine, comprising:
a diesel particulate filter configured for placement in fluid communication with the diesel engine to receive an exhaust flow;
a selective catalytic reduction system configured for arrangement downstream of the diesel particulate filter;
a NOx sensor configured to measure a NOx concentration in the exhaust flow entering the selective catalytic reduction system; and
a controller configured to:
estimate a ratio of NO2 to NOx downstream of the diesel particulate filter based on a factor affecting the generation of NO2 upstream of the selective catalytic reduction system;
adjust the measured NOx concentration based on the ratio to provide an estimated actual NOx concentration; and
dose diesel exhaust fuel into the exhaust flow based on the estimated actual NOx concentration.
 
16. A method of aftertreatment of exhaust from a diesel engine, comprising:
receiving an exhaust flow into a diesel particulate filter and treating the exhaust flow to remove soot and ash;
passively regenerating the diesel particulate filter;
receiving the exhaust flow into a selective catalytic reduction system; and
treating the exhaust flow to reduce a NOx concentration in the exhaust flow, wherein treating the exhaust flow to reduce a NOx concentration comprises:
estimating a ratio of NO2 to NOx downstream of the diesel particulate filter based on a factor affecting the generation of NO2 upstream of the selective catalytic reduction system;
measuring a concentration of NOx in the exhaust flow entering the selective catalytic reduction system;
adjusting the measured NOx concentration based on the ratio to provide an estimated actual NOx concentration; and
dosing diesel exhaust fuel into the exhaust flow based on the estimated actual NOx concentration.