A Proposed Diesel Powertrain to Meet Future Emission Standards and Achieve High Engine Efficiency

摘要

Nowadays, powertrain development activity is performed on the base of fulfilling the stricter emission standards under real driving conditions (RDE). However, the pressure on automotive industry to reduce CO_2 emissions in high efficient diesel applications results in lower exhaust gas temperatures. Therefore, it is highly needed to develop advanced vehicle thermal management methods to both fulfil the targets of emission standards and high thermal efficiency, without increasing dramatically the powertrain cost. The aim of this work is to experimentally demonstrate that by utilizing advanced engine and ATS control methods and revising the engine hardware and subsystems can lead to significant improvement on the fuel efficiency and emissions of the conventional diesel powertrain. The revised engine includes an improved combustion system, completely revised turbocharging and air handling system whilst being heavily reworked with respect to FMEP reduction. The aftertreatment employs a closed coupled electrically heated DOC, SCR on filter with an NH_3 slip catalyst followed by an underfloor SCR and NH_3 slip catalyst. The urea dosing system is utilizing double urea injection to maximize the overall performance. The complete engine and aftertreatment system is controlled by state of the art control system that can maximize the engine efficiency considering the performance of the aftertreatment system, this ensuring emissions compliance in challenging driving missions. The proposed powertrain was extensively tested on the engine dyno. Under steady state conditions, bsfc was improved by more than 15% compared to the reference LDCV diesel engine, while the bsfc area has been widely increased. The finalized powertrain was calibrated to reduce the tailpipe emissions by 50% compared to Euro 6 emission standards while fuel economy was improved by more than 7% compared to the current powertrain. The latter means that diesel powertrain can still be considered as a very effective and clean option due to the further uncovered potential.