Methodology Development for Investigation and Optimization of Engine Starts in a HEV Powertrain
2022-01-0581
3/29/2022
- Content
- The shift towards electrification, and the limitations in battery electric vehicle technology have led to high demand for hybrid vehicles (HEVs), employing a combination of battery and internal combustion engine for propulsion. Although, HEVs enable lower fuel consumption and emissions compared to conventional vehicles, they still employ combustion of fuels for IC engine operation and thus emissions from hybrid vehicles are still a major concern. Engine starts are one of the major sources of emissions during any driving event especially before the three-way catalyst (TWC) has reached light-off temperature. Since, the engine is subjected to multiple starts in most of driving events, it becomes important to mitigate and better understand the impact of these emissions. In this paper, engine starts were studied on a hybrid powertrain with experiments. Emissions and fuel consumption for various engine starting events are investigated and presented when operated under various drive cycles, including WLTC and RTS95. The start events were further categorized based on initial engine and three-way catalyst condition, to better understand and structure the problem. The hardware used for the experiments in this campaign is a 1.5L turbo-charged SI engine with PFI system installed in a P2.5 Hybrid powertrain. The HEV powertrain was installed and operated on a powertrain test bed. Results from the tests were post-processed in AVL Concerto and Python programming language. Increase in fuel consumption is primarily attributed to enrichment of air-fuel mixture during engine restarts whereas tailpipe emissions are mainly contributed when catalyst cools down below efficient conversion temperature during engine off periods. Finally, as an end goal, hypothesis and tests were devised for next campaign, in continuation to this study.
- Citation
- Khatri, J., and Koopmans, L., "Methodology Development for Investigation and Optimization of Engine Starts in a HEV Powertrain ," SAE Technical Paper 2022-01-0581, 2022, .