【作者】 姚永明；

【导师】 刘顺安； 尚涛；

【作者基本信息】 吉林大学 ， 机械电子工程， 2011， 博士

【摘要】 装载机是工程建设的重要机种,其工作特点就是重载、低速、油耗高。为了实现节能目的,本文基于二次调节静液传动技术,在液压恒压网络平台上选取新的二次调节元件液压变压器,构建出了装载机的新的液压系统,在作业时减少液压系统的节流损失以降低油耗,对此节能思路展开的具体工作如下:1.液压变压器结构改进液压变压器的效率是影响装载机节能效果的主要因素之一,针对目前新型液压变压器(IHT)的不足,提出一种双端面配流结构液压变压器(DPPHT),并对其内部主要零件进行受力分析,得出此结构的变压器能有效解决配流盘径向力分布不均及缸体振动等问题,可提高变压器的效率。2.液压变压器功率键合图分析功率键合图理论比较成熟,能以图形化和功率流的方式完成系统建模,能简单地处理系统的线性和非线性关系,进而贴近实际地表述出系统的动态特性及动态变化规律。采用此理论对液压变压器的内部功率流动进行分析,得出其键合图模型后用MTALAB/Simulink仿真得到变压器出口压力随流量变化的响应曲线。3.新液压系统构建与主要元件建模由上述理论构建出装载机恒压网络二次调节液压系统,与现行液压系统比较分析后得出新系统省去了大部分的液压阀,可降低油液流动过程中的节流损失。建立新系统中液压泵、蓄能器、溢流阀等主要元件的数学模型,为下一步仿真做好准备。4.装载机动作仿真与节能分析针对装载机铲斗翻转物料、动臂举升物料与铲斗空载下降工况,在AMESim软件中建立液压变压器的模型,把其封装后建立新液压系统与现行液压系统的模型。仿真后得出前二种工况下液压变压器B口的流量、压力曲线与系统消耗的功率曲线,结果显示新液压系统可降低功率消耗27%左右。铲斗空载下降工况,蓄能器可回收铲斗下降势能60%左右5.系统控制策略研究液压系统具有非线性的特点,为实现工程上精确控制与快速响应,提出基于负载压力的控制策略,并使用神经网络增量PID控制算法设计控制器。对给定的方波、阶跃、正弦三种输入信号,对比神经网络增量PID控制算法与增量PID控制算法的响应,得出前者更加适用于非线性的液压系统。6.台架试验与展望在液压恒压网络试验台上,测试出液压变压器的压力、流量、变压比、效率等性能,并针对变压器驱动液压缸的工况测试了液压变压器的动态特性和节能效果,证实了新液压系统节能的实际可行性。随后指出实车试验与全液压系统驱动装载机是后续研究的重点。总之,本文为装载机的节能研究提供一个新的思路,并做出了前期工作,为后续研究奠定了基础。更多还原

【Abstract】 Loader is one of the most important construction machineries. The characteristics of loader are overloading, low-speed, high fuel consumption. Secondary regulation technology of constant pressure rail and a new secondary regulation element: Hydraulic Transformer(HT) were used on hydraulic system of wheel loader based on hydrostatic transmission technique with secondary regulation in order to improve the situation of high fuel consumption. The main content include that:1. Structure Improvement of Hydraulic TransformerThe efficiency of Hydraulic Transformer is one of the most important factors that affect effect of Loader energy saving.According to the design deficiency of IHT, a structure of double port plates hydraulic transformer (DPPHT) was proposed. The forces of chief elements inside hydraulic transformer were analyzed. The conclusion was drawn that the structure of double port plates can solve the questions of unbalanced distribution for radial force and cylinder vibration.2. Anlysis with Theory of Power Bond GraphThe power bond graph was so mature that it can accomplish system model with figure and power flow.The relation of linearity and nonlinearity can be treated easily with power bond graph because the closeness to fact for the theory. The bond graph model and mathematical model of HT were established. The dynamic response of HT load port used with Matlab/Simulink indicates requirements for actual working conditions were met and further research of hydraulic transformer was achieved. 3. Construction of New Hydraulic System and Building Models of Chief ElementsThe new hydraulic system of loader based on secondary regulation constant pressure rail was established from what we had been studied above. Most hydraulic valves were omitted and throttle loss were decreased compared with current hydraulic system. Mathematical model of pump, accumulator, overflow valve were built in order to prepare for next simulation.4. Action Simulation of Loader and Anlysis of Energy SavingAiming at the work condition of fliping materiel and lifting materiel with booms, the model of hydraulic transformer was built. The models of new hydraulic system and current hydraulic system were built with software named AMESim. The result of curves between flow, pressure, power and time indicated the output power number of new hydraulic system was reduced clearly to 27%. New hydraulic system can recover potential energy of bucket so that the life of loaders will be rised.5. Research on Control StrategyThe nonlinearity is the significant characteristic of hydraulic system. The control strategy based on load pressure so that accurate control and fast response can be achieved. The controller was designed used control algorithm of neural network-incremental PID. The control strategy proposed in this article was suitable for nonlinearity hydraulic system compared the signal response of square wave, step, sine.6. Bench Test and ProspectsThe characteristic experiments of hydraulic transformer on flow, pressure, ratio of transformation,efficiency had been done on the hydraulic constant pressure rail bench. Dynamic characteristics and energy saving effect confirmed the feasibility of new hydraulic system actually. Real train test and full hydraulic drive loader will be the research emphasis.更多还原