两段液压机械无级传动排量控制策略

Study on Displacement Control Strategy of Two Ranges Hydro-mechanical Transmission

在MSC.Easy5中建立了液压机械无级传动系统及排量控制机构的仿真模型,进行了仿真分析。变排量液压元件的排量控制机构存在死区和滞后,节流孔直径越小,死区和滞后越明显。采用阶跃控制电流的方法能有效消除零点处的死区;改变排量控制电流策略可以有效改善液压机械无级传动换段过程的动力学性能,使换段过程中输出转速差、换段时间明显减小,是一种有效的换段过程控制策略。

In order to study the dynamic characteristics of the hydro-mechanical transmission （HMT） system, a simulation model of a two ranges HMT system is established in an object-oriented environment. In virtue of the powerful software tool, the dynamic of the non-linear variable displacement hydrostatic unit is simulated. Based on the analysis of the dynamics characteristics of the hydrostatic transmission mechanism, a displacement control strategy was designed to reduce the non-linear effect of the variable displacement hydrostatic unit and to decrease the speed rising during the range changeover. The simulation results demonstrate the control strategy can decrease the output speed oscillation and improve the shift quality of the HMT system.