拖拉机液压机械无级变速箱的起步特性研究  

Research on starting process of hydro-mechanical continuously variable transmission for tractor

作　　者：耿国盛[1] 周康[1] 肖茂华[1] 张海军[1] 王光明[2] 

机构地区：[1]南京农业大学工学院,江苏南京210031 [2]山东农业大学机械与电子工程学院,山东泰安271018

出　　处：《南京农业大学学报》2016年第2期332-340,共9页Journal of Nanjing Agricultural University

基　　金：农业部948计划资助项目(2010-Z18);江苏省科技支撑计划项目(BE2014134);江苏省产学研联合创新资金项目(BY2014128-04)

摘　　要：[目的]为了提高拖拉机液压机械无级变速箱(HMCVT)的起步性能,本文针对自主研制的新型拖拉机HMCVT进行理论分析与试验研究。[方法]首先,通过分析变速箱起步的边界条件,得到起步时的最大传动比,并根据最大坡度进行校核,从而得到变速箱起步时液压泵排量的控制方案;然后,以试验台架为基础,确定起步过程的评价指标和影响因素;最后,进行液压机械无级变速箱起步性能的影响试验,在试验中,通过单独改变发动机输出转速、负载转矩和泵-马达速比ε的变化速率,从而获得各因素对起步性能的影响规律。[结果]拖拉机无级变速箱起步时通过PLC控制变量泵的排量,使泵-马达的速比ε从0.113逐渐变化到1.000,既避免了马达低速时的死区,又避免了在低效率区工作,同时也满足最大坡度时的起步要求;起步品质的评价指标为起步压力、冲击度、响应时间和速度降;影响起步品质的主要因素依次为负载、液压泵排量、发动机转速。[结论]在不同的负载和驾驶员起步意图下,通过控制变量泵的排量,可以使液压无级变速箱起步时,达到最佳的起步性能及发动机动力性和经济性的目的。[Objectives]In order to improve the starting quality of hydro-mechanical continuously variable transmission（ HMCVT） for tractor,the oretical analysis and experimental research of new type HMCVT are used in this paper. [Methods]First of all,on the research of the initial boundary conditions of transmission,the maximum transmission ratio of the starting time is obtained and maximum gradient is checked,so the starting steps are determined. Then,based on test bench,the starting evaluations of qualities and factors are made. Finally,the experiment of starting process of HMCVT for tractor is made. Engine speed,load and displacement of variable pumpare is changed alone in the test. The experiment provides an important reference for the development of the starting control strategy. [Results]The pump-motor speed ratio ε change from 0.113 to 1.000 are determined by controlling the displacement of variable pump on the starting process of HMCVT. Not only the motor at low speeds dead zone and the transmission working in inefficient areas are avoided,but also the transmission on the maximum gradient is met on the starting steps. The starting evaluation indexes of qualities are starting pressure,degree of jerk,response time and speed drop. Influencing factors about the starting quality follow the order： load,hydraulic pump displacement,engine speed. [Conclusions]Under different load and driver intentions the best starting quality,power performance,and fuel economy for the transmission can be met by controlling the displacement of variable pump on the starting process of HMCVT.

关 键 词：拖拉机 液压机械无级变速箱 起步性能 

分 类 号：S219.032.1[农业科学—农业机械化工程]