一种新型液压机械无级变速器的传动特性研究

摘要

基于传统的单行星排、双行星排传动的液压机械无级变速器,提出了一种复合行星排传动的新型液压机械无级变速器方案.通过行星架固定法推导出了其前进方向无级变速段的速比特性,应用理论力学推导出了其输出转矩特性,计算出了其功率分流比特性.使用Matlab软件绘制了拖拉机速度及变速比随排量比变化特性图、转矩特性图、液压功率分流比特性图.研究结果表明,所设计的新型液压机械无级变速器可在0 ～68 km·h-1的速度实现无级变速,满足了拖拉机在不同工况下的输出转矩要求,多段液压机械无级变速器的功率分流比小于20％,实现了拖拉机的高效、大功率动力传动.通过实例计算验证了新型液压机械无级变速器传动的合理性,为拖拉机自动变速器的开发应用奠定了基础.%Aiming at the limitation of the traditional single epicyclic gearing and double epicyclic gearing transmission of hydraulic mechanical continuously variable transmission,a new type of hydraulic mechanical continuously variable transmission with complex epicyclic gearing transmission is put forward.The speed ratio characteristics of the continuously variable transmission in forward direction are derived by fixing the planetary carriers,the output torque characteristics are derived by theoretical mechanics,and the power split ratio characteristics are calculated.Matlab is used to draw the characteristic diagram of the change of the tractor speed and the speed ratio along with the displacement ratio,and the torque characteristic diagram and hydraulic power split ratio characteristic diagram.The results show that the hydraulic mechanical continuously variable transmission designed can realize continuously variable transmission in the speed of 0 ～ 68 km · h-1,which can satisfy the tractor output torque under different working conditions.The power split ratio of multi range hydraulic mechanical continuously variable transmission is less than 20％,which means the rationality of the transmission of the new type of hydraulic mechanical continuously variable transmission can be verified,so as to lay the foundation for the development and application of the tractor automatic transmission.