摘要
为了满足拖拉机各种作业工况下的行驶速度及动力需求,对拖拉机液压机械无级变速箱的控制与交互系统进行了研究。首先,针对自主研发的某新型液压机械无级变速箱,简要阐述了其液压功率分流机构与无级调速原理,明确了被控对象与控制量。而后,对变速箱的无级调速与负载自适应控制进行了研究,一方面,提出了变速箱速比的点位控制方法,将变速箱速比在全程范围内划分为96帧,作出每一帧与变量泵励磁电压、变量泵流量方向电磁阀、离合器电磁阀的动作关联查询表,通过程序指针的顺序移动实现无级调速与段位切换;另一方面,基于发动机功率控制的要求,提出了一种负载自适应速比调整策略,给出了相应的模糊控制表,并分析了该算法在不同段位区间内的性能;而后,阐述了无级调速拖拉机的交互挡杆与变速箱电子控制单元设计;最后,基于所开发的控制系统进行了拖拉机加速和负载自适应调整试验。研究结果表明,点位控制时拖拉机的速比调节过程较为稳定,属于开环控制;负载自适应控制时的变速箱速比完全取决于负载变化,属于反馈控制。研究结果表明,所设计的控制系统可以很好地对拖拉机液压机械无级变速箱实施控制。
In order to satisfy the tractor speed and power requirements under various operation conditions,the control and interaction system of tractor hydro-mechanical CVT was studied. The principle of power split mechanism and infinite speed variation of a new kind of hydro-mechanical CVT were introduced. And the control method of infinite speed variation and load adaptive adjustment were analyzed. On the one hand,a point-to-point control method was studied through dividing the range of speed ratio into 96 work points,and building the mapping between work point and the actuators such as the exciting voltage of pump, the electromagnetic valve for pump flow direction control, and the electromagnetic valve for clutch control,the controller described the mapping as a control table to realize the infinite speed variation and power shift. On the other hand,based on the target of engine power control,an automatic speed ratio control strategy was proposed to follow the change of load and the corresponding fuzzy control table was acquired. The interaction system and control unit of tractor hydromechanical CVT were designed for further research. Finally,based on the presented control system,some key experiments such as tractor acceleration and load adaptive speed ratio adjustment were made.The test of acceleration showed that there was a stationary process for speed ratio adjustment withalgorithm of point-to-point control under different work conditions due to the open loop control method.The test of load adaptive speed ratio adjustment showed that the speed ratio was quickly changed under different load levels to maintain the constant of engine power because of the closed loop control method.Results showed that the designed control system was reliable and the proposed algorithm was correct.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2015年第6期1-7,共7页
Transactions of the Chinese Society for Agricultural Machinery
基金
农业部引进国际先进农业科学技术计划(948计划)资助项目(2010-Z18)
江苏省科技支撑计划资助项目(BE2014134)
江苏省产学研联合创新资金资助项目(BY2014128-04)
关键词
拖拉机
无级变速箱
点位控制
模糊推理
速比控制
Tractor
Continuously variable transmission
Point-to-point control
Fuzzy reasoning
Speed ratio control
