拖拉机液压机械无级变速器设计

设计了一种液压机械无级变速器,该装置由一个单排行星机构、变量泵定量马达构成的液压传动系统和多挡有级式变速箱组成。在分析液压机械传动形式和液压传动类型的基础上,确定了拖拉机的总体传动方案,对液压元件及机械参数的选择方法进行了阐述,分析了变速器的无级调速特性。绘制了理论牵引特性曲线,分析比较了改进前后牵引特性。装有液压机械无级变速器的拖拉机实现了速度的连续无级变化,在任何牵引力时,发动机都在接近于满负荷点工作,从而大大提高了拖拉机的生产率和燃油经济性。

Design of Hydro-mechanical Continuously Variable Transmission of Tractor

In this paper, a hydro-mechanical continuously variable transmission (HMCVT) for tractors is developed, which is composed of a single planetary gear differential train, a hydraulic transmission system consisted of the variable displacement pump (PV) and the fixed displacement motor (MF) and a multi-gear fixed step ratio transmission. Based on the analysis of types of HMT and styles of hydraulic transmission, the general drive scheme for HMCVT is obtained. The method of selecting the mechanical parameters and hydraulic units are explained, and the stepless speed regulation characteristics of HMCVT is analyzed. The theoretical tractive characteristic curves are drawn. The tractive performance of original tractor and improved tractor are compared. The study shows that the tractor assembled with HMCVT can provide a continuously variable speed. Additionally, in any tractive force, the engine works near full load. As a result, the tractor with the HMCVT demonstrates greatly improved productivity and fuel economy.