Abstract: Hydro-mechanical continuously variable transmission has the advantages of high efficiency and stability, and the domestic research on this technology started late. CASE's PUMA four-segment hydro-mechanical continuously variable transmission is taken as the research object in this paper, and its continuously variable speed regulation, torque characteristics, and hydraulic power shunt ratio are analyzed. The relationship between the input-output speed ratio of PUMA transmission, the hydraulic power shunt ratio and the displacement ratio of variable pump and fixed motor, and the relationship between the torque of the output shaft of the transmission and the output shaft of the motor are given. In the end, based on AMESim software, the simulation model of PUMA transmission is established, and the relationship between its input speed and output speed is simulated and analyzed. The results show that the transmission can realize the continuously variable of the whole speed range of the tractor. The purpose of this study is to provide a reference for the theoretical research and design of stepless transmission.

Key words: Hydro-mechanical continuously variable transmission; Continuously variable characteristics; Torque characteristics; AMESim

摘要： 液压机械无级传动技术具有高效平稳的优点，国内对该技术的研究起步较晚。文章以 CASE 公司的 PUMA 四区段液压机械无级变速器为研究对象，分析了其无级调速特性、扭矩 特性、液压功率分流比，给出了 PUMA 变速器输入输出转速比、液压功率分流比与变量泵和 定量马达排量比的关系式，以及变速器输出轴与马达输出轴转矩的关系。最后，基于 AMESim 平台对 PUMA 变速器进行建模，仿真分析其输入转速与输出转速的关系，结果表明，该变速 器可以实现拖拉机全行驶速度范围的无级调速。该研究旨在为无级变速箱的理论研究和设计 提供参考。

关键词: 液压机械无级变速器；无级调速特性；扭矩特性；AMESim