Study on fuel economy operating modes of tractor equipped with CVT
A simple fuel economy operating mode and a comprehensive fuel economy operating mode of tractor equipped with CVT are proposed in this paper. The former takes the minimum fuel consumption rate point in the whole engine operating range as the target, the throttle opening keeps constant, the gear ratio of CVT is adjusted by the controller which is a single parameter control system. The later takes the optimum fuel economy curve of engine operating as the target, which enables tractor not only to obtain the optimum fuel economy but also to keep a stable speed set by driver under variable resistance. Both throttle opening and gear ratio of CVT are as the control parameters, the controller for this mode is a double parameter control system. In this paper, a single close loop and double close loop control system are established for the two tractor operating modes respectively. Simulation results show that the two kinds of control system can meet the requirements of the simple and the comprehensive fuel economy operating modes. The single closed-loop and the double closed-loop control system can provide an important basis for the development of tractor equipped with CVT.