Title :
Closed loop temperature control of a lean NOx trap during desulfation
Author :
Asik, Joseph R. ; Meyer, Garth M.
Author_Institution :
Powertrain Control Syst. Dept., Ford Motor Co., Dearborn, MI, USA
Abstract :
The design of a temperature control system for a lean NOx trap (LNT) during a desulfation event is described. Lean NOx traps store NOx during lean (fill) A/F operation and release harmless N2 and O2 during rich A/F (purge) operation. The presence of sulfur in the fuel poisons the LNT and reduces its NOx storage capacity. The NOx capacity can be restored through desulfation. The desulfation method used here involves sequential A/F ratio modulation of the engine cylinders. This process generates an exotherm in the LNT. The exotherm must be accurately controlled to avoid over temperature and damage to the LNT and under temperature to avoid ineffective desulfation. The control system described contains both feedforward and feedback elements. Values for the control parameters were determined through system identification
Keywords :
chemical variables control; closed loop systems; feedback; feedforward; internal combustion engines; parameter estimation; temperature control; N2; NO; NOx storage capacity; O2; closed loop temperature control; desulfation; exotherm; lean NOx trap; temperature control system; Chemicals; Control systems; Earth; Engine cylinders; Feedback; Fuel storage; Mechanical power transmission; System identification; Temperature control; Toxicology;
Conference_Titel :
American Control Conference, 1999. Proceedings of the 1999
Conference_Location :
San Diego, CA
Print_ISBN :
0-7803-4990-3
DOI :
10.1109/ACC.1999.783233
