拖拉机液压机械无级变速器速比匹配设计与实验

Design and Experiment of Hydro-mechanical CVT Speed Ratio for Tractor

液压机械无级自动变速器能够根据拖拉机作业模式的差异,实现不同作业模式下发动机转速、转矩的匹配。将液压机械前进区段设计为等比四区段,各区段传动公比φ为1.88,纯液压区段用于拖拉机低速爬行作业以及起步。基于液压机械换段等比传动的连续性,对各区段齿轮的参数以及传动比进行设计,并对变量泵和定量马达的匹配进行选型。加载实验中模拟拖拉机不同作业模式的负荷,进行了液压机械各区段下的发动机最佳经济点的速比匹配。验证了变速箱在各区段之间的平稳换段以及拖拉机平稳加速的连续性响应。

According to the difference of the tractor operating mode, the hydro-mechanical automatic transmission can automatically complete the change of transmission ratio and achieve the match of the speed and torque of the engine under different operating modes. The forward section of the designed hydraulic machinery adopted four sections of geometric proportion. Each section transmission common ratio was 1.88. Pure hydraulic section of the designed hydraulic machinery was used for the start of the tractor. Based on the continuity of the transformation of different segments of speed ratio, the gear ratio and power match of variable displacement pump and quantitative motor of each drive pair was determined. Also, the load characteristics of the tractor under various operation modes were combined. The speed ratio match of the optimal economic point of the engine of four sections of the hydraulic machinery was determined. Then, the continuity of the segments of transmission between different sections of hydraulic machinery and continuity output response of smooth acceleration of the tractor were verified.