Simulation investigation on fluid characteristics of jet pipe water hydraulic servo valve based on CFD

Simulation investigation on fluid characteristics of the water hydraulic jet pipe servo valve （WHJPSV） is conducted through a commercial computational fluid dynamics （CFD） software package FLUENT. In particular, the factors to fluid characteristics of WHJPSV are addressed, which include diameter combination of jet pipe and receiver pipe, jet pipe nozzle clearance, angle between two jet receiver pipes and deflection angle of the jet pipe. It is concluded from the results that： （i） Structural parameters have great influences on fluid characteristics of WHJPSV, when d1 = d2 = 0.3 mm, α= 45 , b = 0.5 mm, and the simulation exhibits better fluid characteristics; （ii） The magnitude of the recovery pressure and flow velocity increase almost linearly with the deflection angle of jet pipe. The research work in this paper is important for determining and optimizing the structural parameters of the jet pipe and jet receiver. The relevant conclusions could be extended to the study of other water hydraulic servo control components.

Characteristics Prediction Method of Electro-hydraulic Servo Valve Based on Rough Set and Adaptive Neuro-fuzzy Inference System

Synthesis characteristics of the electro-hydraulic servo valve are key factors to determine eligibility of the hydraulic production. Testing all synthesis characteristics of the electro-hydraulic servo valve after assembling leads to high repair rate and reject rate, so accurate prediction for the synthesis characteristics in the industrial production is particular important in decreasing the repair rate and the reject rate of the product. However, the research in forecasting synthesis characteristics of the electro-hydraulic servo valve is rare. In this work, a hybrid prediction method was proposed based on rough set（RS） and adaptive neuro-fuzzy inference system（ANFIS） in order to predict synthesis characteristics of electro-hydraulic servo valve. Since the geometric factors affecting the synthesis characteristics of the electro-hydraulic servo valve are from workers＇ experience, the inputs of the prediction method are uncertain. RS-based attributes reduction was used as the preprocessor, and then the exact geometric factors affecting the synthesis characteristics of the electro-hydraulic servo valve were obtained. On the basis of the exact geometric factors, ANFIS was used to build the final prediction model. A typical electro-hydraulic servo valve production was used to demonstrate the proposed prediction method. The prediction results showed that the proposed prediction method was more applicable than the artificial neural networks（ANN） in predicting the synthesis characteristics of electro-hydraulic servo valve, and the proposed prediction method was a powerful tool to predict synthesis characteristics of the electro-hydraulic servo valve. Moreover, with the use of the advantages of RS and ANFIS, the highly effective forecasting framework in this study can also be applied to other problems involving synthesis characteristics forecasting.

New Method to Improve Dynamic Stiffness of Electro-hydraulic Servo Systems

Most current researches working on improving stiffness focus on the application of control theories.But controller in closed-loop hydraulic control system takes effect only after the controlled position is deviated,so the control action is lagged.Thus dynamic performance against force disturbance and dynamic load stiffness can’t be improved evidently by advanced control algorithms.In this paper,the elementary principle of maintaining piston position unchanged under sudden external force load change by charging additional oil is analyzed.On this basis,the conception of raising dynamic stiffness of electro hydraulic position servo system by flow feedforward compensation is put forward.And a scheme using double servo valves to realize flow feedforward compensation is presented,in which another fast response servo valve is added to the regular electro hydraulic servo system and specially utilized to compensate the compressed oil volume caused by load impact in time.The two valves are arranged in parallel to control the cylinder jointly.Furthermore,the model of flow compensation is derived,by which the product of the amplitude and width of the valve’s pulse command signal can be calculated.And determination rules of the amplitude and width of pulse signal are concluded by analysis and simulations.Using the proposed scheme,simulations and experiments at different positions with different force changes are conducted.The simulation and experimental results show that the system dynamic performance against load force impact is largely improved with decreased maximal dynamic position deviation and shortened settling time.That is,system dynamic load stiffness is evidently raised.This paper proposes a new method which can effectively improve the dynamic stiffness of electro-hydraulic servo systems.

基于SimHydraulics的电液伺服系统实物仿真

针对一个采用阀控对称缸的电液伺服系统进行了SimHydraulics实物仿真,根据仿真结果辨识出系统的数学模型,通过与机理建模和Simulink模型仿真的结果相对比进行了验证。总结了综合应用SimHydraulics与Simulink的新仿真方法,该方法使得电液伺服系统的设计和控制方案的选择可以同步进行,提高了系统设计的效率和准确性。

A seventh-order model for dynamic response of an electro-hydraulic servo valve

In this paper, taking two degrees of freedom on the armature–flapper assembly into account, a seventh-order model is deduced and proposed for the dynamic response of a two-stage electro-hydraulic servo valve from nonlinear equations. These deductions are based on fundamental laws of electromagnetism, fluid, and general mechanics. The coefficients of the proposed seventhorder model are derived in terms of servo valve physical parameters and fluid properties explicitly.For validating the results of the proposed model, an AMESim simulation model based on physical laws and the existing low-order models validated by other researchers through experiments are used to compare with the seventh-order model. The results show that the seventh-order model can reflect the physical behavior of the servo valve more explicitly than the existing low-order models and it could provide guidance more easily for a linear control design approach and sensitivity analysis than the AMESim simulation model.

Static Characteristics of the New Type Nozzle Flapper Amplifier for Double Nozzle Flapper Electro-Hydraulic Servo Valve

A new type nozzle flapper amplifier for double nozzle flapper electro-hydraulic servo valve is proposed in the paper.The electro-mechanical converter of new type nozzle flapper amplifier is designed by using the piezoelectric bimorph and beryllium-bronze materials.The structure and working principle of the new type nozzle flapper amplifier are introduced.Pressure characteristic and flowrate characteristic are analyzed by experimental method.The research results show that pressure characteristic has large amplification factor and output pressure;flowrate characteristic has large linear range and output flowrate.

机械反馈式伺服阀流量测试动态缸参数选用分析

相比电反馈伺服阀动态特性可直接通过阀芯位移响应测试获得,机械反馈式流量伺服阀的动态特性,通常需利用动态缸作为流量传感器间接测量获得。测试结果受动态缸泄漏、阻尼、质量惯性等固有非理想化因素的影响,通常无法准确表达伺服阀本身的性能指标。基于一套实际阀控缸系统,建立Matlab-Simulink仿真模型,解析获得的频带宽结果相比实测结果误差小于0.5%,由此建立了可准确表达阀与缸性能特性的仿真模型。在此基础上,理论给出了伺服阀本身的频率特性指标,即无泄漏无阻尼及无限刚度动态缸条件下的系统频率特性。以此为依据,分析了实际动态缸活塞质量、活塞粘性阻尼以及泄漏变化情况下,阀控缸系统频率特性偏离理想条件的变化规律。

液压伺服滑阀工作边冲蚀行为及影响因素

液压伺服滑阀阀口工作边易受油液中颗粒污染物的冲蚀作用,诱发伺服阀性能退化。采用阀口工作边淹没射流冲蚀可视化实验和固液两相流数值计算方法,研究颗粒冲击工作边的冲蚀行为及影响因素。结果表明:颗粒冲击工作边的冲蚀行为主要有刮擦-滑动、碰撞-滑动、悬浮-翻转以及边碰行为;1.05 MPa下,边碰行为颗粒的最大速度可达40.41 m/s,冲击能最高,且反弹速度最小仅4.59 m/s,对工作边产生的冲蚀破坏最大;1.2 MPa颗粒冲击比与边碰率比0.9 MPa和1.05 MPa更高,分别为46%和7%;冲击比和边碰率随粒径增大而增加;低黏度油液的冲击比和边碰率大于高黏度油液,黏度为0.01634 Pa·s时分别可达94%和17%。研究结果对揭示液压伺服滑阀冲蚀破坏机理及抗冲蚀设计具有重要意义。

电液伺服控制阀动态仿真与试验

电液伺服阀被广泛应用各种自动化装备中,这种复杂的机电控制系统集机、电、液、磁于一体,属于重要的随动跟踪控制元件,伺服控制除了有良好的静态性能外,其动力学特性决定了伺服系统工作精度.运用键合图理论建立电液伺服阀的键图模型;推导模型的状态空间方程和输出方程;运用仿真软件MATLAB/Simulink进行了仿真,分析电液伺服阀系统动态特性.最后在搭建的实验验证平台上验证了系统的动态性能,并与仿真结果进行了比较分析.结果是该电液伺服阀的动态特性指标超调量40%、响应时间13ms、上升时间2ms左右.

工业用电液伺服阀故障统计分析和使用维护建议

在工业领域中,常用的电液伺服阀主要有直驱式伺服阀、喷嘴挡板两级伺服阀、射流管两级伺服阀以及三级伺服阀。根据伺服阀维修业务中收集到的1176例伺服阀故障,对常见电液伺服阀故障原因进行了分析、归类统计和研究。为工业用电液伺服阀的选型提供了参考,也针对电液伺服阀的使用维护提出了建议。

非对称喷嘴挡板压力伺服阀建模与特性研究

针对一种具有非对称喷嘴挡板结构的压力伺服阀(简称非对称压力阀),建立其数学模型及MATLAB/Simulink仿真模型,分析了整阀的静动态性能,并研究了非对称结构的设计原则。结果表明:该阀为带死区的单向正增益压力伺服阀,其输出压力高、线性度好、动态响应快;喷嘴腔压力和输出压力交叉点与静态性能指标具有唯一的映射关系,可利用交叉点位置来判断伺服阀性能是否达到工作要求;阀芯端面面积非对称是前置级非对称的来源,为了保证非对称压力阀的零位稳定性和性能要求,需将前置级设为非对称形式,其固定节流孔液阻系数比大于喷嘴孔液阻系数比,而喷挡间隙的非对称有利于减小喷嘴结构参数的影响,便于伺服阀的尺寸设计和调试;最后通过实验验证了数学模型的准确性。建立的数学模型及仿真模型可为压力伺服阀的结构设计及优化提供依据。

飞机襟翼阀控伺服作动系统动态性能分析

由于阀控伺服作动系统存在的非线性因素,传统的建模方法所建立的数学模型无法准确地反映系统实际情况。为提升液压系统的控制精度及动态响应性能,解决在实际系统试验中出现的动态特性超差问题,对可能引起的因素及关键参数进行研究,重点分析引起系统静态误差的主要因素,同时分析系统各关键元件的固有频率和阻尼比对系统动态性能的影响。利用Matlab/Simulink软件对系统进行非线性建模,理论推导计算及仿真结果分析表明,较高的系统各关键元件固有频率和阻尼比有利于提高系统动态性能。

高精度的动态加载系统建模与控制算法试验研究

为设计全程静态精度小于0.05%FS、动态精度小于1%FS的动态力加载装置,文中在缺乏匹配的压力型电液伺服阀的情况下,采用流量型电液伺服阀设计了动态加载装置的液压系统,并对高精度动态加载的控制算法进行了试验研究。试验结果表明:采用传统PID控制加载力,其静态精度可达0.041%FS,动态精度可达2.5%FS,均超过动态加载装置的控制要求;采用自适应PID控制加载力,其静态精度可达0.039%FS,施力中间阶段的加载力动态精度可达1%FS,但在施力初始阶段和施力结束阶段,加载力动态精度高达8%FS,考虑加载力在施力过程中呈现阶段性特点,提出采用分段自适应PID控制算法,经动态加载力试验论证,分段自适应PID算法能够有效解决加载力动态精度超差问题,加载力的静态精度可以控制在0.018%FS,动态控制精度可以控制在1%FS,完全满足高精度动态加载装置的控制要求。

某型电液伺服阀振动故障研究

针对某型号伺服阀在进行试验过程中出现的振动故障,通过建立振动故障树模型,对可能造成伺服阀振动故障的污染因素、滑阀故障因素、力矩马达故障因素和前置级故障因素等进行试验验证及仿真计算,确定了故障原因及机理,并提出了解决方案。

飞机拦阻系统的改进及建模分析

针对纯机械式液压拦阻系统不能对不同质量和降落速度的飞机快速有效拦阻的问题,对原来的系统进行改进,采用电液伺服阀替换原来的凸轮阀和针阀,采用伺服电机控制的液压泵替换原来的制动盘传动比控制的液压泵,建立改进后的飞机拦阻系统的数学模型,并用MATLAB/Simulink建立仿真模型,对飞机速度、飞机拦停距离和飞机过载等受控参数的变化规律进行了仿真分析,模拟了飞机拦阻系统的工作过程,对拦阻系统的性能进行了仿真验证。结果表明:改进的拦阻系统对多种型号飞机在拦阻距离、飞机加速度、飞机速度、拦阻力和刹车压力均满足预设的拦阻指标且曲线平稳、没有大的突变。

一种节能降噪的液压阀性能检测试验台液压系统

为解决液压阀性能检测试验台液压系统因溢流和节流产生的发热严重、噪音大等问题,提出将伺服电机和定量泵的组合作为液压阀试验台的液压源,通过检测液压阀的输出流量来控制电机转速。通过控制每个时间点的液压泵输出流量略大于液压阀测试所需流量来保证溢流阀的溢流作用。仿真和试验结果表明,液压阀测试液压系统可在保证正常工作的基础上实现节能和降噪,效果分别为33.6%和12.0%。研究成果可为液压试验台设计提供一定参考。

液压伺服阀阀芯结构优化及实验验证

以减小阀芯在工作中所受的液动力为目标,以阀芯的外形结构参数为优化变量,对液压伺服阀阀芯结构优化的方法进行了研究。使用SPEA2算法对阀芯的结构进行了多目标优化设计,获得了Pareto最优的阀芯结构设计方案。利用CFD仿真软件计算了优化前后阀芯流场和压力分布,验证了优化效果。搭建了一套实验平台,对优化前后的阀芯液动力进行测试,通过测量阀芯在工作时的速度以及受力情况等参数,计算出阀芯在工作过程中所受的稳态液动力。测试结果显示,经结构优化后的阀芯在不同开口位移下所受的液动力均出现了下降,稳态液动力平均下降14.86%,其变化趋势与仿真计算一致,均在阀口开口位移为0.6 mm时具有最大的优化效果,进一步验证了优化方案的可行性。

基于TimeGAN的电液伺服阀性能评估模型

电液伺服阀容易受到油液污染的影响,当污染颗粒通过节流口时会对阀口壁面产生冲蚀磨损,使得电液伺服阀阀口过流断面变大,内泄漏量增加。针对现有仿真手段难以准确衡量电液伺服阀的性能退化,而试验样本有限等问题,提出一种基于时间序列生成对抗网络算法的评估模型用于评估电液伺服阀性能。首先分析了电液伺服阀的失效机理,然后建立了时间序列生成对抗网络算法的框架,利用维纳过程分析并得到了电液伺服阀的性能评估模型,最后设计并完成了污染磨损试验,利用时间序列生成对抗网络算法对试验数据扩充,通过参数估计的结果对比发现,利用时间序列生成对抗网络算法对试验数据扩充可以有效提升电液伺服阀性能评估模型的准确度。

伺服电机液压系统在密炼机上的应用

针对密炼机节能环保的发展趋势,公司联合供应商开发了新型的密炼机伺服电机液压系统,代替常规的异步电机比例阀液压系统。该液压系统能根据密炼机的各个动作按需提供压力和流量,具有噪音低、对油液清洁度要求低、节能明显等优点。

基于双层CESO的电液伺服系统线性自抗扰控制

针对含高频噪声的阀控非对称缸不确定扰动抑制问题,采用扰动频率分层技术,利用线性扩张状态观测器低通滤波特性以及扰动估计速度和精度与带宽取值正相关性的特点,提出一种基于双层级联扩张状态观测器的阀控非对称缸电液伺服系统线性自抗扰方法。在分析双层级联线性扩张状态观测器稳定性基础上,与传统线性自抗扰控制方法进行了仿真对比研究。仿真结果表明:该控制方法继承了传统自抗扰控制优点,提高了不确定扰动估计速度和精度,有效抑制了含高频测量噪声不确定扰动带来的不利影响,可实现阀控非对称缸电液伺服系统的高性能控制。