Research on shift schedule modification based on load rate

This paper investigates a linear modification method of heavy-duty vehicles’ shift schedule based on vehicle load rate. The load rate has been proposed to recognize the road slope in real-time. Firstly, two kinds of special condition called zero-load-rate condition and full-load-rate condition are defined. Dynamic shift schedule under each condition is obtained respectively from steady state experiment. The load rate is derived from vehicle dynamic theory. Secondly, vehicle shifting speed is calculated by linear interpolation method using the current load rate. Finally, simulation and test bench experiments are carried out. It is verified that the current road condition can be identified in real-time to keep the vehicle in appropriate gear. By the method in this paper, phenomenon of shift hunting is eliminated and vehicle power demand is satisfied.