【作者】 潘旭东；

【导师】 卢泽生； 王广林；

【作者基本信息】 哈尔滨工业大学 ， 机械制造及其自动化， 2008， 博士

【摘要】 电液伺服控制系统广泛应用在航天、航空和航海等航行器的航行控制领域中,电液伺服阀作为电液伺服控制系统的核心元件,其性能直接影响整个伺服控制系统的品质。滑阀是由阀芯和阀套两部分组成,通常用作电液伺服阀的功率放大级,其精度要求高,加工难度大。阀芯和阀套的轴向配合尺寸的加工是伺服阀制造过程中的关键工序,这种轴向配合尺寸通常称之为叠合量。叠合量的实质是指滑阀在零位时的阀口开启状态的数值,由于滑阀通常有四个阀口,所以需要有四个叠合量数值需要保证。叠合量一般为1-2μm,公差要求约为±0.5μm,通常是通过磨削阀芯台肩的方式来达到和调整阀芯各节流边的轴向尺寸,进而保证叠合量的要求,实际加工是通过测量——磨削——再测量直到达到精度要求为止。各个阀芯和阀套之间并没有互换性,加工方式是一种偶件配作的方式,因此叠合量加工和测量可称作为“配磨”加工。由于没有互换性,不能通过单独测量某个阀芯节流边轴向位置尺寸来计算和控制叠合量的数值,必须配合对应的阀套一同测量,而通过分别测出相配对的阀芯阀套各自的节流边轴向尺寸经计算得到叠合量的方法也不便采用。必须将阀芯阀套装在一起测量相对的工作边开口情况(即叠合量),因此叠合量的测量一直以来是伺服阀制造中的难点之一。目前我国伺服阀生产主要以军品为主,当单件小批试制性生产时,滑阀的配磨工序已经是影响伺服阀生产效率的瓶颈之一了。随着航空航天事业的不断发展,对伺服阀也提出了批生产的要求,滑阀叠合量的测量精度和效率更成为伺服阀制造中的技术关键,因此研究滑阀叠合量测量技术对提高伺服阀的制造工艺水平,进而提升军工生产能力有着重要意义和应用前景。对滑阀阀口的流量特性进行研究,为叠合量液动测量提供理论基础。利用CFD数值模拟的方法,仿真分析了理想阀口、阀芯工作棱边带圆角阀口和有径向间隙的阀口的流量特性。针对阀口流体流态变化对阀口流量系数的影响,建立了阀口流量系数与雷诺数之间数学模型,适用于滑阀阀口流体在不同流态下的流量系数的计算。在此基础上,建立了新的阀口流量的数学模型。该模型中综合了阀口流态变化对阀口流量的影响,相对于传统的小孔出流模型,阀口流体流量的计算不受阀口流体流态变化的影响,更加适合于描述滑阀阀口流量。进行阀口流量特性实验,验证数值模拟和建立的数学模型的正确性。在深入分析了伺服阀滑阀叠合量气动测量方法缺点的基础上,提出了一种采用液压油作为测量介质的流量式叠合量测量方法,即“流量式”液动测量法。通过测量滑阀阀口四条流量特性曲线,利用回归的方法计算出滑阀的叠合量。建立了滑阀叠合量测量的误差模型,将测量误差分为结构误差和流态误差两种。结构误差主要受阀口阀芯当量圆角和径向间隙的影响,流态误差受阀口流体流态的影响,给出了叠合量计算时误差补偿的方法。针对目前伺服阀滑阀叠合量测量技术和系统对于伺服阀滑阀尤其是大流量伺服阀滑阀叠合量测量精度不高和测量数据不准确的问题,研制新的测量系统,提高叠合量测量精度,保证测量数据准确性,并能够适应于多型号不同流量范围的伺服阀滑阀叠合量测量,提高叠合量测量设备的通用性,实现叠合量的自动测量。阀口压差的稳定是高精度液动测量的保证,因此深入研究了阀口压差控制技术。压差控制系统由定量泵-电液比例溢流阀控系统组成,采用PID控制方法,通过压力传感器反馈阀口压差,得到阀口压差的偏差值作为PID控制器输入的闭环控制方法。在深入研究了流量计的压力损失特性的基础上,为提高压差控制系统的性能,提出一种基于前馈的复合PID控制策略,并通过实验验证了该控制方法的有效性和优点。液压油温度变化是对测量精度影响的主要因素之一,因此深入研究了液压油温度控制技术。实现了一种压缩机——电加热器的温度控制方法。并针对压缩机制冷控制中存在非线性时变的特点,将一种自适应模糊控制算法应用到了压缩机系统蒸发器过热度的控制中。这种算法实现量化因子和比例因子的自整定。为验证控制效果,进行了蒸发器过热度控制实验,对比分析模糊控制器和自适应模糊控制器的控制效果。更多还原

【Abstract】 Electro-hydraulic servo control system is widely applied in the navigating control field for astronavigation, navigation and aviation, and as the key part of electro-hydraulic servo control system, the performance of electro-hydraulic servovalve takes an important role on the servo control system. Spool valve is composed of valve spool and valve sleeve, and as the power stage of servo valve, it has a high degree of accuracy and is difficult for machining. The mate-grinding for axial mate dimension of valve spool and valve sleeve is the key process during machining, and the axial mate dimension is called as overlap values. Actually, overlap value reflects the opening state of spool’s null position, and there are four orifices on a spool valve, so there are four overlap values. The overlap value is 1-2μm, and the tolerance is about±0.5μm. Generally, grinding on valve spool shoulder is the way for getting and adjusting the overlap value, which is ensured by the process of repeatedly measuring and grinding practically. Each valve spool or valve sleeve does not have the capability of interchangeable assembly, spool valve couple is made by so called matching part mate machining, so the spool null cutting and measuring are called as“mate-grinding”. According to the above analysis, it is unable to calculate and control the overlap value by individually measuring the axial position dimension of throttling edge for each valve spool. Moreover, the method of measuring axial position dimension of each throttling edge for valve spool and the mate valve sleeve and calculating the overlap value is infeasible, and it is necessary to measure the relative opening state of working edge by assembling the valve spool and valve sleeve, so to measuring overlap value of spool valve is a difficulty in servovalve industry. At present, servovalves are mainly produced for military demands, which belong to small batch production and trial-manufacture, the produce of spool valve is the bottle-neck problem which decreases production efficiency. With the development of navigation and astronavigation industry, the large batch production of servovalves is bringing forward, and spool valve overlap measuring precision and efficiency has became the key point in servovalve machining process, the reaserch on the measuring technology for overlap value of spool valve has an important significance for increasing national defense strength and application foreground.This dissertation researches on the discharge characteristic of spool valve orifice, and analyzes the discharge characteristics of ideal orifice, and actual orifice which has round angle on spool working edge and diametral clearance using CFD numerical simulation method. In order to analyze effect of flow pattern change of fluid’s contribution on orifice discharge coefficient, this dissertation develops a mathematic model about discharge coefficient versus Reynolds number, this model can be used to calculate discharge coefficient of spool valve fluid in the different flow patterns. Based on this foundation, obtains a new flow rate formula for orifice, which discards the impact of changing of flow pattern, and has a commonality for describing the discharge characteristic of spool valve orifice. And a verification experiment has been made to ensure the formula is correct.Based on thorough analyzing the disadvantages of the pneumatic measurement for servovalve overlap value, this dissertation proposes a flow measurement method adopted hydraulic oil as the measuring medium, which is called as flow hydraulic measurement method. For measuring the four discharge characteristic lines of spool valve, and then calculates overlap values by regression method. This dissertation develops the error model of overlap measurement, which divides the source of errors into structural errors and flow pattern errors. The structural errors come from the round angle and the diametral clearance of spool valve. The flow pattern errors are affected by fluid flow pattern, and an error compensation method was put forward for calculating overlap values.The present servovalve spool valve overlap value measurements and systems have low degree of precision and inaccuracy data for measuring large flow servovalves. In order to solve this problem, a new measuring system has be developed in this dissertation, which improves measuring precision, insures data accuracy, and can adapt to overlap value measuring for multi types of different flow range servovalve, improves the versatility of measuring equipment and realizes automatic measurement.Constant orifice differential pressure is the premise for high accuracy hydraulic measuring, so thorough analyse of orifice differential pressure control technology has been taken. Differential pressure control system is composed of a constant flow pump-electro hydraulic proportional safety valve system, using PID closed loop control method. On the basis of thorough analysis of pressure drop of flowmeter, in order to improve the controller performance, this dissertation develops a compound PID control strategy based on feedforward control, and a verification experiment is made for approving the validity and merits of this method.Hydraulic oil temperature is one of main influence factors for measuring, so this dissertation researches the hydraulic oil temperature control technology in detail. This dissertation develops a compressor-electric heater temperature control method, and considers the non-linearity time-variation feature in compressor refrigeration control, and a self-adapting fuzzy control algorithm has been utilized in compressor system superheat control. Quantization and proportion factors can be self-adjusted in this algorithm. And an evaporator superheat experiment is made. The control results between normal fuzzy controller and self-adapting fuzzy controller has been compared in this experiment.更多还原