Abstract: In order to adapt to the complex working conditions of the tractor and improve its working efficiency, a design scheme of tractor hydrostatic power split CVT (Continuously Variable Transmission) was proposed in this paper. Firstly, the transmission principle of the CVT was introduced.Then, according to the parameters of the engine and rear axle, as well as the speed requirements of the tractor, the transmission parameters and structure of the CVT were designed. Finally, the simulation model of the CVT was built under AMESim, and its speed regulation characteristics were analyzed. The research results show that the transmission can realize the stepless speed regulation of the tractor in the range of 0-30 km/h, and has small hydrostatic splitting power under key working conditions such as ploughing to save energy. The ratio of pump to motor displacement of the transmission needs to be quickly modulated from 1 to -0.85 during shift to ensure that the tractor has the same driving speed before and after shift. It has a certain reference value for the domestic application of CVT tractors in China.

Key words: tractor, continuously variable transmission, power split, simulation, AMESim

摘要： 为适应拖拉机复杂的作业工况并提高其作业效率，提出一种单行星输入耦合型液压功率分流无级变速箱的设计方案。依据拖拉机配套动力与速度要求进行变速箱参数设计与结构设计，基于SolidWorks构建变速箱虚拟样机，并基于AMESim构建变速箱传动系统模型，对其整机调速特性进行分析。研究结果表明:该变速箱可以实现拖拉机在0~30km/h范围内的无级调速，且在犁耕等重点工况下具有较小的液压分流功率从而实现节能；该变速箱在段位切换时需要将泵马达排量比从1快速调制-0.85，通过快速的马达反向实现行星排复位与换段前后的速度衔接。对我国无级变速拖拉机的国产化设计与应用具有一定的参考价值。

关键词: 拖拉机, 无级变速箱, 功率分流, 仿真, AMESim