液压机械全功率换段方法及功率过渡特性  

Full power shift method of hydro-mechanical transmission and power transition characteristics

作　　者：杨树军[1] 鲍永[1] 范程远 

机构地区：[1]燕山大学车辆与能源学院,秦皇岛066004

出　　处：《农业工程学报》2018年第5期63-72,共10页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金面上项目(51675462;51175449);河北省高校科技支撑项目(ZD2016012)

摘　　要：为了解决液压机械无级传动换段过程中存在的动力中断和换段冲击等问题,基于当前段与目标段双制动器结合重叠,提出全新的液压机械全功率换段方法,并深入探究全功率换段过程功率过渡机理及控制方法。该文以两段等差式液压机械为研究对象,在双制动器结合重叠的动力换段方式的基础上,提出了五阶段液压机械全功率换段方法,通过理论分析与试验相结合的方法,研究了换段过程中液压机械转矩特性和功率特性随液压回路压差的变化规律,液压回路压差随变排量液压元件排量的变化规律。结果表明,在双制动器结合重叠的动力换段中,通过调节变排量液压元件的排量比,能够控制液压回路的高低压侧压差改变、互换,进而控制当前段制动器转矩向目标制动器有序转移,在双制动器结合重叠中完成换段,实现换段过程传递全功率。输入转速保持1 000 r/min不变,进出换段时定排量液压元件转速无波动,输出扭矩波动量约为5 N·m(负载扭矩为60 N·m和150 N·m)。该研究揭示了液压机械全功率换段的功率过渡机理,可为全功率换段的后续研究及液压机械应用提供了参考。Hydro-mechanical variable transmission(HMT) is applicable to high-power vehicles, because of its ability to achieve high-power stepless speed changing and high transmission efficiency. However, in general power shift, the target range brakes would be engaged after the current range brakes are disengaged, which would cause immediate output power interruption. In the shift process, there are load reverses in hydraulic transmission unit, power flow reverses in hydraulic branch, and function interchanges in hydraulic component. Simultaneously, high and low pressure circuits in hydraulic circuit interchange, as a result of which the rotational speed of hydraulic component changes abruptly, causing the fluctuation of output speed as well as vibrations and noises. To solve the problems of HMT in power shift, a new full power shift method of HMT is proposed based on the double brakes of the current range and target range overlapping. The process of full power shift is divided into 5 stages: current range, prior stable stage, power transition stage, post stable stage and target range. For the HMT working at current range, when the ideal power shift timing comes, the target range brake would be engaged with zero speed difference; and when the HMT comes to the prior stable stage, its torque and power characteristics remain unchanged. Regulating properly the displacement ratio of variable-displacement hydraulic component can make the high and low pressure circuits of hydraulic circuit interchange. The original low pressure side is pressurized to the target range pressure, the torque moves from current range brake to target range brake, and HMT comes to the post stable stage with its torque and power characteristics remaining identical with those of the target range. The current range brake is disengaged at zero torque, HMT enters the target range, and therefore the power shift process is fulfilled. The interchange between high and low pressure as well as power transition is made when the double brakes overlap. In the power s

关 键 词：制动器 控制 液压机械无级传动 动力换段 全功率换段 功率过渡 

分 类 号：U463.2[机械工程—车辆工程]