【作者】 许有熊；

【导师】 李小宁；

【作者基本信息】 南京理工大学 ， 机械制造及其自动化， 2009， 博士

【摘要】 气动比例压力阀是实现连续控制及气、电、机一体化的关键元件。其中,数字控制比例阀(简称数字阀)具有可直接与计算机连接,不需要D/A转换器,具有结构简单、成本低、可靠性高等优点,因此得到越来越广泛的应用且成为当前的研究热点之一。但目前现有的脉冲开关式数字比例压力阀通常采用高速电磁铁为电-机械转换器,这种驱动方式的数字比例压力阀存在响应速度慢、稳念精度差等缺点,无法满足如快速燃气喷射系统和精密气动定位系统等需要快速响应高精度的场合。因此,迫切需要研究一种新型的具有快速响应和高精度特性的数字比例压力阀。论文从此实际需求出发,对所涉及的问题进行了全面、深入的理论和试验研究。首先,论文通过深入分析了以电磁铁为驱动器的传统开关式数字比例压力阀工作过程,指出了提高阀响应速度和控制精度的最根本途径是提高驱动器的动态性能。为此,提出了一种新型的以压电驱动代替电磁驱动、具有快速响应和高精度特性的压电开关调压型气动数字比例压力阀的构想。在功能需求分析基础上,研究了其前置级压电快速驱动-位移放大、摆动开关挡板式先导阀结构及膜片平衡式主阀结构等关键技术；提出并实现了一种压电驱动-放大、先导开关挡板高速通断、膜片式主阀功率放大和压力-电反馈的新型压电开关调压型气动数字比例压力阀的总体结构,并采用模块化设计方法完成了该总体结构的设计。设计了基于弹性铰链的具能放大压电叠堆输出微位移的先导开关挡板机构,并采用有限元分析方法对其进行了静、动态特性和疲劳寿命等分析。为了分析压电开关调压型气动数字比例压力阀的静、动态特性以及各主要结构参数、控制参数等对其主要性能的影响,也为阀结构参数和控制参数的合理设计提供理论依据,论文研究了其动态特性数学模型,并进行了相关的仿真研究。试验结果与仿真结果对比验证了所建阀的数学模型及仿真模型是准确的。通过仿真研究,了解了阀工作过程中的静、动态特性,明确了先导开关挡板行程、先导阀通流直径和主阀芯通流直径、阀腔室体积、PWM载波频率及PID控制等对阀主要性能的影响,为后续的深入研究提供了理论指导。研制了压电开关调压型气动数字比例压力阀试验样机。在此基础上,构建了具有高速实时采集和数字比例控制功能的试验控制系统,并对前置级压电驱动-放大机构、先导级摆动开关挡板阀、压电开关调压型气动数字比例压力阀进行了基本的开环静、动态测试。试验结果表明：前置级先导开关挡板放大机构阶跃上升时问约为0.57ms,阶跃下降时间约为0.3ms,具有较快的响应速度和良好的工作频宽；可通过控制PWM脉宽比数字控制先导级摆动开关挡板阀的出口流量,具有一定的实用性,适用于小流量、控制精度要求不高的应用场合；所研制的压电开关调压型气动数字比例压力阀的空载流量和出口压力与脉宽比具有一定的线性度,且能实现大流量输出。最后,为了提高压电开关调压型气动数字比例压力阀动态性能,提高其稳态精度和降低压力波动,对其进行了控制算法研究。采用了Bang-Bang开关控制和带死区P+PWM复合控制算法,实现了阀的数字比例控制,但其稳念控制性能较差,存在-定的稳态误差和压力波动,特别是在有流量负载下。通过试验发现,数字阀的压力响应延迟是影响阀性能的一个主要因素,为此,提出了PWM控制算法的一种改进形式：调整变位PWM法；并采用Bang-Bang控制+带死区P+调整变位PWM复合控制算法对数字阀进行了控制。通过试验验证了其算法的有效性,能有效提高阀稳念控制精度,大大降低压力波动,特别是在有流量负载下,稳态误差由2kPa降为1kPa,压力波动由15kPa降为5kPa。完成了所研制的压电开关调压型气动数字比例压力阀试验样机与同级别的传统电-气比例压力阀的性能比较试验。试验表明：在相同条件下所研制试验样机的响应速度和稳态精度较同级别电-气比例压力阀都有明显的提高,响应速度提高了约66%,稳态精度提高了约50%,具有高速、高精度的特点,具有广阔的应用前景。更多还原

【Abstract】 Pneumatic proportional pressure valve is the key component of continuous control and the integration of pneumatic, electronic and mechanical. Directly controlled by the computer without D/A converter, with the advantages of simple structure, low cost and high reliability and so on, the digital control of pneumatic valve has gained more and more popularity and become the focus of recent research. However, the traditional on-off type digital electro-pneumatic proportional pressure valve driven by the electro-mechanical converter of electromagnet has the disadvantages of slow response and poor control precision etc, due to the driving component made of electromagnet, cannot meet the certain requirements of high frequency response and high precision, which are commonly required in the rapid gas injection system and the precision pneumatic positioning system, etc. Therefore, it is an urgent need to develop a new type of high-frequency and high-precision digital proportional pressure valve. To achieve this goal, a thorough theoretical and experimental research on the interrelated problem is performed in this thesis.First of all, based on the deep analysis of the working cycle of the traditional on-off type electro-pneumatic digital proportional pressure valve driven by electromagnet actuator, it is found that the most fundamental way to improve the valve response speed and control precision is to improve the actuator dynamic performance. Therefore, the conception of novel piezoelectric on-off pressure-regulation type electro-pneumatic digital proportional pressure valve (PDPPV for short) with rapid response and high precision driven by the piezoelectric actuator is proposed. Based on its functional analysis, the key technologies of the prestage of piezoelectric rapid driven and displacement amplification, the structure of swing-switch flapper type pilot valve and diaphragm-balance type main valve are researched. Furthermore, the overall structure of the novel PDPPV is presented and designed by using modular design method. Its prestage is the piezoelectric stack actuator whose output displacement is amplified by the pilot switch flapper amplification mechanism based on flexure hinge and its pilot stage is the two-position three-way swing-switch flapper type valve with the high speed on-off function. And its power stage is diaphragm balanced main valve to enlarge the output flow. Moreover, the pilot switch flapper amplification mechanism is designed and the finite element analysis of its static, dynamic and fatigue life characteristics is correspondingly conducted.In order to analyze the static and dynamic response characteristics of the PDPPV and the effect of main structural parameters and control parameters on its performance, as well as to provide the theoretical basis for the appropriate design of its structure parameters and control parameters, the PDPPV dynamic characteristics mathematical model is established and the relevant simulation research is finished. By the comparison between simulation and experiment results, the built mathematical model is proved to be accurate. Through simulation studies, the static and dynamic characteristics on working process of the valve are understood and the effects of pilot switch flapper displacement, the flow passage diameter of pilot valve and main valve, the chamber volume of the valve, PWM carrier frequency and PID control on the PDPPV main performance are also deeply clarified, which will provide theoretical guidance to further deep research.Based on the previous work, the experimental prototype of the PDPPV is developed and the corresponding test and control system for the function of high speed real time collection and digital proportional control is built. The static and dynamic tests on the prcstage piezoelectric driven-amplification mechanism, the pilot stage (swing-switch flapper type valve) and the PDPPV are conducted. These tests indicate that:(1) the step rise-time of the pilot switch flapper is about 0.57ms and the step-fall time is about 0.3ms, with faster response speed and wider working bandwidth; (2) it is practical to digitally control the export flow of the swing-switch flapper type valve by regulating the PWM duty cycle, which makes it applicable to the application situation of small flow and low demand of control accuracy; (3) the unloaded flow and outlet pressure of the developed PDPPV have a certain degree of linearity with the PWM duty cycle and the PDPPV has large output flow.Finally, in order to improve the dynamic performance and steady-state accuracy of the PDPPV and decrease its pressure fluctuations, its control algorithms are researched. The Bang-Bang control algorithm and the compound control algorithm of P with dead zone plus PWM can basically achieve the digital proportional control of the PDPPV, but its steady-state control performance is poor, with the disadvantages of some steady-state error and pressure fluctuations, especially under the flow load conditions. The experimental research found that the pressure response delay of the PDPPV is the major influence factor of the valve performance. According to this reason and the work characteristics of the PDPPV, based on PWM control algorithm, an adjusted-shift PWM algorithm (AS-PWM) is presented. Moreover, the compound control algorithm using Bang-Bang Control, P with dead zone and AS-PWM is proposed to control the PDPPV. Experimental results show that with this controller, the PDPPV control performance can be effectively improved, especially under flow load conditions, which the steady-state error reduces from 2kPa to 1kPa and pressure fluctuations reduces from 15kPa to 5kPa.The performance comparison experiments of the developed PDPPV experimental prototype and the traditional electro-pneumatic proportion pressure valve is conducted. Experiments indicate that under the same experimental conditions, compared with the traditional electro-pneumatic proportion pressure valve, the PDPPV has better performance in response speed and steady-state accuracy, which the response speed improves by about 66% and the steady-state accuracy improves by about 50%. The PDPPV has great dynamic characteristics and high-speed, high-precision characteristics, with good industrial application prospect.更多还原