Energy efficiency analyses of a vehicle in modal and transient driving cycles including longitudinal and vertical dynamics

- Presenting a new approach to study rolling loss in different driving cycles.
- Providing a more realistic contribution of rolling loss mechanism in driving cycles.
- Considering the environmental impacts of chassis and tyre in homologation process.
- The current driving cycles need to be improved and consider chassis contributions.
- Camber changes have less contribution on final results than the toe angle changes.

The growing concerns about the environmental issues caused by vehicles and a strive for better fuel economy, urge the legislators to introduce conservative regulations on vehicle testing and homologation procedures. To have accurate evaluations, driving cycles that can sufficiently describe the vehicles' conditions experienced during driving is a prerequisite. In current driving cycles there are still some issues which are disregarded. The aim of the presented work is to study the contribution of chassis and vehicle dynamics settings on tyre rolling loss in comparison with the original assumptions made in the NEDC, FTP and HWFET driving cycles. A half-car model including a semi-physical explicit tyre model to simulate the rolling loss is proposed. For the chosen vehicle and tyre characteristics, depending on the specific chassis settings and considered driving cycle, considerable difference up to 7% was observed between the energy consumption of the proposed- and conventional approach. The current work aims to provide the legislators with a better insight into the real effects of chassis and vehicle dynamics during the certification process to further improve the test related procedures required for homologation such as generation of road load curves. I.e., the aim is not to provide a new homologation process, since there are also other effects such as road roughness and tyre temperature that need to be considered. The results are also of interest for the vehicle manufacturers for further considerations during test preparation as well as in the development phase in order to reduce the environmental impacts.