Abstract
Recently, HMT(hydro-mechanical transmission) is expected as a viable solution for agricultural vehicles such as tractor to meet the fuel efficiency and working convenience. In order to apply the HMT to tractor, a proper control of engine-HMT is required. A HMT consists of a HSU(hydro static unit), a planetary gear set, and clutches. In this paper, a performance simulator is developed based on dynamic models of the tractor and HMT including the HSU and sub-shift part using AMESim and MATLAB/Simulink. An integrated engine-HMT control algorithm for a tractor is proposed focusing on the working performance. To evaluate the control algorithm, simulation is performed in the field circumstance. It is found from the simulation results that the engine speed is maintained at the demanded speed by the engine and the HMT gear ratio control.
KEYWORDS – CVT(continuously variable transmission), HMT(hydro-mechanical transmission), HSU(hydro-static unit), working convenience, PTO(power take-off)