A study on the skip shift control strategy according to driving resistance of heavy-duty vehicle equipped with multi-speed transmission

The multi-speed transmission system has been increasingly applied of late to improve fuel economy and driver convenience. A commercial vehicle requires a larger number of transmission steps than a passenger vehicle because the traveling load varies depending on the cargo load amount and the road surface condition. In the multi-speed transmission system, many shifts occur within a short time under low-speed and low-load conditions. Therefore, proper skip-shift control is required. In this study, the skip-shift control strategy of multi-speed transmission vehicles was studied, and the logic was verified through simulation. The shift time was determined by predicting the driving time after the shift, and it was found that the lighter the vehicle or the smaller the road load is, the more frequent the skip-shift.