Tier2Bin5 대응 NOx Storage Catalyst 적용 2.2L 디젤 엔진에서의 에미션 개발

The LNT(Lean NOx Trap) system has been developed for NOx reduction to meet Tier2 Bin5 by using the modified R-2.2 standard Engine. The rich mode combustion in the engine has been developed for the wide operating range despite of low compression ratio. It can be accomplished by adjusting air and FIE system, mainly by increasing attached-post-injection quantity. The A/F (Air/Fuel) ratio has been sustained by controlling the attached-post-injection quantity. The neutral transition between lean mode and rich mode combustion has been completed. The change in noise and torque cannot be recognized by the driver during the transition of combustion mode (lean/rich/lean). The transition procedure has been finished within about 1s for whole operating range. The regeneration pattern decides where the rich mode should be realized. It has been calibrated for FTP test mode to obtain proper NOx conversion rate to meet Tier2Bin5 considering the fuel penalty and THC slip. The total rich mode time during FTP mode was around 30s and the NOx conversion rate of 92% has been realized with bench aged NSC(NOx Storage Catalyst) appropriate to 50k mileage.