拖拉机动力换挡变速器换挡特性与控制策略研究  

Shift Characteristics and Control Strategy of Powershift Transmission on Tractor

作　　者：席志强[1,2] 周志立[2] 张明柱[2] 曹青梅[1] 

机构地区：[1]西安理工大学机械与精密仪器工程学院,西安710048 [2]河南科技大学车辆与交通工程学院,洛阳471003

出　　处：《农业机械学报》2016年第11期350-357,共8页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家自然科学基金项目(51375145);河南省重点科技攻关计划项目(102102210165);洛阳市重大科技专项(1001001A)

摘　　要：拖拉机动力换挡变速器通过控制多组湿式摩擦离合器之间的转矩传递来实现不停车换挡,具有不会因超载使发动机熄火、起步性能好、能降低外载荷突然变化所引起的传动系统振动与冲击等优点。换挡离合器的分离与接合时序是影响拖拉机换挡平顺性和操作舒适性的关键因素。本文研究了换挡过程动态特性分析方法,引入变速器输出转速和输出转矩作为拖拉机生产率和动力性的评价指标,弥补了传统换挡品质指标不能对拖拉机性能进行评价的不足。运用动力学原理构建动力换挡变速器模型,研究了不同换挡重叠时间下的离合器载荷、滑摩功与功率特性,确定了动力换挡变速器换挡品质的控制方法及控制策略。提出以动力换挡变速器输出转速变化幅值为指标来优化换挡重叠时间与离合器接合油压,通过仿真验证了拖拉机换挡过程中离合器控制策略的有效性。仿真结果表明,通过该优化算法所选择的换挡参数受拖拉机牵引载荷变化影响较小,变速器输出转速过渡平稳,可减少负向输出转矩的产生,避免换挡过程中拖拉机减速或动力传递中断,提高了换挡品质。Through control of the torque transfer among several groups of wet friction clutch to realize gear shift in traveling, powershift transmission of tractor has a series of advantages, such as the engine will not flameout when overloaded, good starting performance, reducing the vibration and shock of transmission system caused by suddenly load changes. The separation and joint timing of the gear-shift clutch is the key factor that affects the shifting smoothness and operating comfort of the tractor. The dynamic properties analysis method of the shift process was studied. It introduced transmission＇ s output speed and output torque as indexes to evaluate the productivity and power of tractor, which made up for the deficiency of traditional shift quality indexes cannot evaluate the performance of the tractor. Based on the dynamic principle, the transmission system model of the power shift tractor was constructed. The dynamic characteristics of the shift process were analyzed to research the load and power flow of clutch. The control method and control strategy of power-shift transmission＇s shift quality were determined. Taking the output speed variation amplitude as index to optimize shift overlap time and contact oil pressure of the clutch. The control strategy of clutch was verified by simulation. The simulation results showed that the gearshift parameters chosen with the optimization algorithm were less affected by the change of tractor traction load, and the transmission output speed was transitioned smoothly. It can reduce the negative output torque generated, which avoided tractor deceleration or power transfer interruption during gearshifting, and improved the shift quality.

关 键 词：拖拉机 动力换挡变速器 换挡特性 控制策略 

分 类 号：S232.3[农业科学—农业机械化工程] S24[农业科学—农业工程]