Challenges and Solutions to Improve Engine Start Stop Comfort English Free Members only

Market analyses reveal rising applicationsof automatic start stop systems in conventional and hybrid vehicles because they provide an important contribution in fuel economy with respect to CO2-reduction and they are mandatory for full hybrid vehicles. Following, the event of an engine start stop is getting more in focus of vehicle refinement and tends to substitute idle comfort in importance from the NVH point of view, since idle time is becoming shorter by the application of start stop systems. In this context comfort and NVH aspects of start stop systems will continue to play an important role for customer acceptance.
In this paper, the start stop event will be analysed and measures to improve the start stop behaviour will be discussed. Therefore the start stop process of combustion engines is considered as a functional chain from excitation over amplification mechanisms acting on the vehicle body and finally on the passengers. The functional chain is lined up in three fields to display the causality of the different influencing parameters: “Engine Excitation at Start/Stop”, “P/T Body Oscillation System” and “Vehicle Body”. For each field exemplarily parameters are chosen to improve the start/stop behaviour. Further on, the advantage of a 24V starter regarding vibration reduction is outlined.