超高压液压脉冲波形的产生与应用

发布时间：2018-12-20 08:21

【摘要】：液压系统由于其功率重量比大、响应速度快、控制性能好、可实现过载保护等优点而广泛应用于汽车、工程机械、农业机械和国防等诸多领域。液压系统在工作过程中,由于液压阀的开闭或换向导致油液流动的方向迅速改变或突然停止流动,在流动液体和运动部件的惯性下,油液瞬间被压缩,系统压力出现瞬间上升,产生液压脉冲。通常情况下,这种瞬间上升的压力峰值可达正常压力的若干倍,从而给液压系统带来不利影响甚至灾难性后果。因此,为了提高液压系统的可靠性,需要对液压元件进行脉冲试验,而脉冲试验的关键是产生符合标准的液压脉冲波形。液压系统近年来朝着高压大流量方向发展,也对液压脉冲波形产生系统提出了更高的要求。由于超高压液压脉冲波形产生系统涉及超高压、大流量的电液伺服控制,对于超高压液压脉冲波形产生系统的研究不仅能应用于液压元件的脉冲试验,也有助于推动相关领域理论、技术和装备的发展。论文以超高压液压脉冲波形产生系统为研究对象,以降低系统能耗、提高系统响应速度与精度为目标,采用理论分析、计算机仿真、数学计算和试验研究相结合的方法,对超高压液压脉冲波形产生系统进行了系统、深入的研究。论文提出了基于二级阀控制腔压差反馈的超高压液压脉冲波形产生系统,并研制了试验样机,可以产生方波、水锤波、正弦波等多种液压脉冲波形；采用蓄能器对将负载在回程阶段释放的高压油液能量吸收、储存起来,在下一个增压冲程阶段释放,实现了超高压液压脉冲波形产生系统节能,使得系统总能耗降低；提出了模糊重复控制策略,并应用于超高压液压脉冲波形产生系统,并与PID控制系统进行了对比,试验结果表明模糊重复控制器的采用明显降低了系统跟随误差。有关各章内容分述如下：第一章,从液压脉冲的产生和广泛存在出发,阐述了液压脉冲试验的重要性；总结了液压脉冲试验标准的发展和国内外研究现状,论述了标准液压脉冲波形的产生方法；介绍了超高压液压技术、液压系统节能技术和液压系统控制策略等相关技术进展。第二章,提出了超高压液压脉冲波形产生系统,建立了系统的数学模型和AMESim仿真模型；设计了采用复合节流窗口的液控阀,以实现不同阀芯开口时的不同流量增益,可以满足超高压液压脉冲波形产生系统负载变化范围较大的需求；通过调节液控阀控制腔的压差反馈增益,可以改变系统阻尼比,进而实现对系统超调量的控制,提供了一种在方波输入的情况下产生可控制的水锤波的方法,也为水锤波试验提供了理论依据。第三章,采用蓄能器对超高压液压脉冲波形产生系统进行了节能设计,以回收系统在回程阶段的能量；分析计算了系统的功率、能耗、效率等,并与不采用蓄能器的液压系统进行了对比；采用蓄能器进行节能设计后,系统总能耗降低15%,总效率从63%提高到76%；采用蓄能器的液压系统,对于阶跃输入、方波输入、水锤波输入信号的响应也明显优于不采用蓄能器的系统,尤其是响应速度显著提高；同时提供了一种直接跟随输入指令信号的脉冲波形产生方法,可以产生方波、水锤波等脉冲波形。第四章,通过分析超高压液压脉冲波形产生系统的数学模型,得出其开环增益随着负载变化而变化的特点,因而采用传统控制策略难以同时实现稳定性及精确性的要求；在分析重复控制策略优劣的基础上提出了模糊重复控制策略,并应用于超高压液压脉冲波形产生系统；采用模糊重复控制策略后系统跟随误差随着循环次数的增加逐步减小,证明了系统的精确性、收敛性及稳定性。第五章,将设计的节能型超高压液压脉冲产生系统应用于软管脉冲试验,并研制了试验样机；对基于液控阀压差反馈的液压系统的超调量进行了试验研究,证明了可以通过调节压差反馈增益实现不同的超调量,进而得到目标波形；对于采用蓄能器的节能型超高压液压脉冲波形产生系统进行了试验研究,证明蓄能器的采用明显提高了系统的控制性能,同时提供了一种直接跟随输入指令信号的脉冲波形产生方法；对模糊重复控制策略与PID控制策略进行了对比试验研究,试验结果表明,在循环10个周期以后,模糊重复控制系统对于正弦波输入和水锤波输入的周期综合误差分别比传统PID控制系统降低了99%和87%,相对误差分别降低了54%和40%。第六章,概况了全文的主要研究工作和成果,并展望了今后需要进一步研究的工作和方向。
[Abstract]:The hydraulic system has the advantages of large power weight ratio, high response speed, good control performance, and can realize overload protection and the like, and is widely applied to many fields such as automobile, engineering machinery, agricultural machinery and national defense. During the working process, the hydraulic system changes or suddenly stops the flow in the direction of oil flow due to the opening and closing or reversing of the hydraulic valve, and under the inertia of the flowing liquid and the moving part, the oil is instantly compressed, and the pressure of the system is instantaneously increased to generate a hydraulic pulse. In general, such an instantaneous rise in pressure peaks may be several times the normal pressure, which adversely affects even catastrophic consequences for the hydraulic system. Therefore, in order to improve the reliability of the hydraulic system, it is necessary to perform a pulse test on the hydraulic element, and the key to the pulse test is to generate a hydraulic pulse waveform that meets the standard. The hydraulic system has been developed in the high-pressure and high-flow direction in recent years, and the higher requirements for the hydraulic pulse waveform generation system are also put forward. Because the high-pressure hydraulic pulse waveform generation system relates to the electro-hydraulic servo control of the ultra-high pressure and the large flow, the research of the high-pressure hydraulic pulse waveform generation system can not only be applied to the pulse test of the hydraulic element, but also can promote the development of the theory, the technology and the equipment in the relevant field. The paper takes an ultra-high pressure hydraulic pulse waveform generation system as a research object to reduce the energy consumption of the system, improve the response speed and the precision of the system, and combine the theory analysis, the computer simulation, the mathematical calculation and the test research. In this paper, a systematic and in-depth study of the high-pressure hydraulic pulse waveform generation system is carried out. In this paper, an ultra-high pressure hydraulic pulse waveform generation system based on the feedback of the differential pressure of the two-stage valve control chamber is proposed, and a prototype is developed, which can generate various hydraulic pulse waveforms such as square wave, water hammer wave and sine wave. the high-pressure oil energy absorbed by the load in the return phase is absorbed and stored by the energy accumulator, the high-pressure hydraulic pulse waveform generation system is released under the next boosting stroke stage, the total energy consumption of the system is reduced, and a fuzzy repeated control strategy is proposed, The system is applied to the high-pressure hydraulic pulse waveform generation system and compared with the PID control system. The results show that the use of the fuzzy repeat controller significantly reduces the following error of the system. The contents of the relevant chapters are as follows: Chapter one, starting from the generation and extensive existence of hydraulic pulse, expounds the importance of the hydraulic pulse test, summarizes the development of the hydraulic pulse test standard and the research situation at home and abroad, and discusses the generation method of the standard hydraulic pulse waveform; The technical progress of the high-pressure hydraulic technology, the energy-saving technology of the hydraulic system and the control strategy of the hydraulic system are introduced. In the second chapter, an ultra-high pressure hydraulic pulse waveform generation system is proposed, the mathematical model of the system and the AMESim simulation model are established, and a liquid-controlled valve with a compound throttling window is designed to realize different flow gains in different valve core openings. the system damping ratio can be changed by adjusting the differential pressure feedback gain of the liquid-controlled valve control cavity, The invention provides a method for generating a controllable water hammer wave in the case of a square wave input, and also provides a theoretical basis for the water hammer wave test. In the third chapter, the energy-saving design of the high-pressure hydraulic pulse waveform generation system is carried out by using the energy accumulator, so as to recover the energy of the system in the return phase, and the power, energy consumption and efficiency of the system are calculated and compared with the hydraulic system without the accumulator. With the energy-saving design of the energy accumulator, the total energy consumption of the system is reduced by 15%, the total efficiency is increased from 63% to 76%, and the hydraulic system with the energy accumulator is also obviously superior to the system without the energy accumulator for the response of the step input, the square wave input and the water hammer wave input signal. in particular, that response speed is obviously improve; meanwhile, a pulse waveform generation method which directly follow the input command signal is provided, and a pulse waveform such as a square wave and a water hammer wave can be generated. In the fourth chapter, through the analysis of the mathematical model of the high-pressure hydraulic pulse waveform generation system, it is concluded that the open-loop gain of the high-pressure hydraulic pulse waveform generation system is changed with the change of the load, so that the requirement of the stability and the accuracy is difficult to be realized at the same time by adopting the traditional control strategy; Based on the analysis of the advantages and disadvantages of the repetitive control strategy, a fuzzy repeat control strategy is proposed and applied to the high-pressure hydraulic pulse waveform generation system. The system following error is gradually reduced with the increase of the number of cycles after the fuzzy repeat control strategy is adopted, and the accuracy of the system is proved. convergence and stability. In chapter 5, the design of the energy-saving ultra-high pressure hydraulic pulse generation system is applied to the hose pulse test, and a test prototype is developed, and the overshoot of the hydraulic system based on the differential pressure feedback of the liquid-controlled valve is studied. It is proved that different overshoot can be realized by adjusting the feedback gain of the differential pressure, and then the target waveform is obtained; for the energy-saving ultra-high pressure hydraulic pulse waveform generation system with the energy accumulator, the system has been tested, and the adoption of the energy storage device has obviously improved the control performance of the system, the invention provides a method for generating a pulse waveform directly following an input instruction signal, The cycle synthesis error of the fuzzy repeat control system for sine wave input and water hammer wave input is lower by 99% and 87% than the traditional PID control system, and the relative error is reduced by 54% and 40%, respectively. In chapter 6, the main research work and results of the full text are introduced, and the work and direction of further research will be expected in the future.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TH137

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