US 11,702,973 B2
Controlling urea injection in exhaust after treatment systems
Jonas Jansson, Hönö (SE); Björn Henriksson, Gothenburg (SE); and Lars Carlhammar, Lindome (SE)
Assigned to VOLVO TRUCK CORPORATION, Gothenburg (SE)
Filed by VOLVO TRUCK CORPORATION, Gothenburg (SE)
Filed on May 20, 2022, as Appl. No. 17/664,336.
Claims priority of application No. 21175937 (EP), filed on May 26, 2021.
Prior Publication US 2022/0381171 A1, Dec. 1, 2022
Int. Cl. F01N 3/20 (2006.01); F01N 3/035 (2006.01); F01N 13/00 (2010.01)
CPC F01N 3/208 (2013.01) [F01N 3/035 (2013.01); F01N 3/2066 (2013.01); F01N 13/009 (2014.06); F01N 13/0093 (2014.06); F01N 2250/02 (2013.01); F01N 2560/026 (2013.01); F01N 2570/14 (2013.01); F01N 2590/08 (2013.01); F01N 2610/02 (2013.01); F01N 2610/146 (2013.01); F01N 2900/14 (2013.01); F01N 2900/1402 (2013.01); F01N 2900/1812 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A method for controlling urea injection in an exhaust aftertreatment system comprising at least a first catalytic reduction device arranged downstream of a first urea injector, and a second catalytic reduction device arranged downstream of a second urea injector, the method comprising:
injecting urea at a flow rate upstream of the first catalytic reduction device;
measuring a level of nitrogen oxides downstream of the first catalytic reduction device and upstream of the second catalytic reduction device;
controlling the flow rate of the urea injection until the measured level of nitrogen oxides fulfils a predetermined condition;
reducing the flow rate of the urea injection;
when the measured level of nitrogen oxides is decreasing in response to reducing the flow rate of the urea injection, reducing the flow rate of the urea injection further, and
controlling a flow rate of urea injection using the second urea injector upstream of the second catalytic reduction device according to the measured level of nitrogen oxides downstream of the first catalytic reduction device and upstream of the second catalytic reduction device.