油液特性对液压机械无级传动换段性能的影响研究

发布时间：2018-01-03 03:34

本文关键词：油液特性对液压机械无级传动换段性能的影响研究　出处：《燕山大学》2012年硕士论文　论文类型：学位论文

【摘要】：液压机械无级传动综合了机械传动效率高和液压传动无级变速的优点，是重型车辆较理想的传动形式。换段过程控制是提高液压机械无级传动性能的关键问题，换段过程中液压传动单元负载扭矩反向，闭式液压回路高低压边互换，引起马达转速突变，造成动力瞬时中断、系统速比波动，，并伴随振动和噪声，油液性能与液压机械无级传动换段动态特性密切相关。本文开展了液压机械无级传动换段过程建模、动态特性及其影响因素仿真分析，换段控制等研究，获得油液特性对换段过程性能的影响规律。主要研究内容包括：(1)分析了液压机械无级传动换段过程的速度特性、扭矩特性、功率流以及换段过程动态特性的影响因素，指出油液特性、负载扭矩、换段时机与换段动态特性密切相关；(2)建立了液压机械无级传动换段过程数学模型及仿真模型，包括变排量液压元件模型、定排量液压元件模型、负载模型和油液模型等，应用MATLAB/Simulink进行了仿真分析，仿真结果表明液压油含气量越大，油液体积弹性模量越小，换段时定排量液压元件转速波动越大，换段品质降低；(3)分析了负载变化对系统换段动态特性的影响规律，指出前段离合器分离与后段离合器结合重叠负载控制策略能有效降低定排量液压元件的转速波动；开展了换段过程控制策略研究，提出调节变排量液压元件排量比控制方法，有效降低了定排量液压元件转速波动。
[Abstract]:Hydraulic machinery stepless transmission combines the advantages of high efficiency of mechanical transmission and continuously variable speed of hydraulic transmission and is the ideal transmission form of heavy vehicle. The key problem of improving the performance of hydraulic machinery stepless transmission is to change the stage process control. In the process of changing section, the load torque of hydraulic transmission unit is reverse, the high and low pressure side of closed hydraulic circuit is interchangeable, which causes the sudden change of motor speed, the instantaneous interruption of power, the fluctuation of system speed ratio, and the accompanying vibration and noise. The oil performance is closely related to the dynamic characteristics of hydraulic machinery stepless transmission. In this paper, the modeling of hydraulic machinery stepless transmission stage changing process, dynamic characteristics and its influencing factors simulation analysis, section changing control and other research are carried out. The main research contents include: (1) the speed characteristic and torque characteristic of hydraulic machinery stepless transmission are analyzed. The influence factors of the power flow and the dynamic characteristics of the switching process are pointed out. The oil performance, load torque and timing are closely related to the dynamic characteristics of the changing stage. The mathematical model and simulation model of hydraulic machinery stepless transmission are established, including variable displacement hydraulic element model, constant displacement hydraulic element model, load model and oil fluid model, etc. The simulation results with MATLAB/Simulink show that the larger the gas content of hydraulic oil, the smaller the bulk elastic modulus of oil, and the greater the fluctuation of rotational speed of hydraulic components with constant displacement. The quality of changing segment was decreased; The influence of load change on the dynamic characteristics of the system is analyzed. It is pointed out that the combination of front clutch separation and rear clutch overlapping load control strategy can effectively reduce the speed fluctuation of constant displacement hydraulic components. The control strategy of changing stage process is studied, and the method of regulating the displacement ratio of variable displacement hydraulic components is put forward, which effectively reduces the fluctuation of rotational speed of constant displacement hydraulic components.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH137

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