RESEARCH ON THE PERFORMANCE OF NEW TYPE OF PROPORTIONAL PESSURE AND FLOW CONTROL VALVE

A new closed loop flow controlling principle through correcting the valve'sopening area while load pressure is changing is carried out. Further more a principle using only oneproportional valve to compound control pressure and flow is suggested. By using very simpleproportional throttle valve in structure, the functions that five kinds of proportional valves orany two of them combined possess can be complimented. After analyzing, comparing, and testing thedynamic and static characteristics of valve with different controlling principles and main valvestructure styles, the optimized structure styles and control methods are achieved.

Flow Control for a Two-Stage Proportional Valve with Hydraulic Position Feedback

The current research mainly focuses on the flow control for the two-stage proportional valve with hydraulic position feedback which is named as Valvistor valve.Essentially,the Valvistor valve is a proportional throttle valve and the flow fluctuates with the change of load pressure.The flow fluctuation severely restricts the application of the Valvistor valve.In this paper,a novel flow control method the Valvistor valve is provided to suppress the flow fluctuation and develop a high performance proportional flow valve.The mathematical model of this valve is established and linearized.Fuzzy proportional-integral-derivative(PID)controller is adopted in the closed-loop flow control system.The feedback is obtained by the flow inference with back-propagation neural network(BPNN)based on the spool displacement in the pilot stage and the pressure differential across the main orifice.The results show that inference with BPNN can obtain the flow data fast and accurately.With the flow control method,the flow can keep at the set point when the pressure differential across the main orifice changes.The flow control method is effective and the Valvistor valve changes from proportional throttle valve to proportional flow valve.For the developed proportional flow valve,the settling time of the flow is very short when the load pressure changes abruptly.The performances of hysteresis,linearity and bandwidth are in a high range.The linear mathematical model can be verified and the assumptions in the system modeling is reasonable.

Improving the Performance of an Electro-Hydraulic Load-Sensing Proportional Control Valve

The paper deals with the simulation and the experimental verification of the hydraulic behavior of an electro-hydraulic load-sensing proportional control valve. An innovative CAE （computer aided engineering） methodology, developed combining CFD （computational fluid dynamics） simulations with lumped and distributed numerical modeling, is firstly introduced and tailored by comparing the numerical results with measurements coming from an experimental campaign performed for a wide range of pressure loads and metered flow rates. Then, both the reliability and the limits of the numerical approach are highlighted through a detailed numerical vs. experimental comparison, involving the pressure of the main hydraulic lines, the flow rate through the first section and the local compensator displacement. Finally, the CAE methodology has been applied for assessing the internal ducts hydraulic permeability and the local compensator spring pre-load influence on the control valve metering curves. At the end of this analysis, an optimized design configuration, featuring a maximum controlled volumetric flow rate increased of more than 25%, has been proposed.

Investigation of Semi-Active Hydro-Pneumatic Suspension for a Heavy Vehicle Based on Electro-Hydraulic Proportional Valve

Hydro-pneumatic suspension is widely used in heavy vehicles due to its nonlinear characteristics of stiffness and damping. However, the conventional passive hydro-pneumatic suspension can’t adjust parameters according to the complicated road environment of heavy vehicles to fulfill the requirements of the vehicle ride comfort. In this paper, a semi-active hydro-pneumatic suspension system based on the electro-hydraulic proportional valve control is proposed, and fuzzy control is used as the control strategy to adjust the?damping force of the semi-active hydro-pneumatic suspension. A 1/4?semi-active hydro-pneumatic suspension model is established, which is co-simulated with AMESim and MATLAB/Simulink. The co-simulation results show that the semi-active hydro-pneumatic suspension system can significantly reduce vibration of the vehicle body, and improve the suspension performance comparing with passive hydro-pneumatic suspension.

Design of a 70 MPa Two-Way Proportional Cartridge Valve for Large-Size Hydraulic Forging Press

For an ultra-high-pressure hydraulic transmission system of a large-size hydraulic forging press(LHFP),a 70 MPa two-way proportional cartridge valve has been developed to improve the power weight ratio of the hydraulic forging press.In this study,a nominal diameter 25 mm(DN25)cartridge valve is taken as the research object.A longer concentric cylindrical annular gap is set to effectively prevent the ultra-high-pressure oil from flowing to the pilot stage and a seated valve structure is set to form the linear sealing zone in the closing state of the main valve port.Electric-displacement feedback is adopted to realize precise control of the main valve port flow and the features of this valve are investigated.In order to verify the strength and static and dynamic characteristics,the finite element model and a simulation model of the valve proposed above are built.There is a little deformation which does not affect the main valve spool movement,and the main valve port flow meets the design demands.Then,the prototype of DN2570 TPCV is manufactured and a ultra-high-pressure experimental platform is developed.The experimental results show that the DN2570 TPCV designed in this study has the advantage of fast response,high control precision,and low leakage,which can meet the requirements of LHFPs.

比例减压阀控缸输出力的非线性自适应控制

针对所研制的一款采用双直动式三通比例减压阀控非对称液压缸驱动的刮板型输送带清扫器进行研究,提出了一种基于PI(Prandtl-Ishlinskii)逆模型前馈补偿的自适应控制算法,改善了比例减压阀固有的压力滞环、死区、增益等非线性,保证了清扫器刮板驱动扭矩的精度,实现了以恒定扭矩在刮板全寿命周期内的高效清洁.针对比例减压阀的滞环特性,采用带遗忘因子的递推最小二乘法在线辨识比例减压阀的PI模型参数,进而求解其逆模型作为线性自抗扰控制器的前馈补偿.仿真和实验结果表明,所提算法有效减小了比例减压阀的滞环、死区和增益等非线性,改善了比例减压阀控缸的动态响应,相较于PID算法,跟踪速度提升了65%,在100~700N·m范围内刮板驱动扭矩误差可控制在±2N·m以内.

A differential control method for the proportional directional valve

For the proportional directional valve controlled by two proportional solenoids, the normal control method(NCM) energizes only one solenoid at a time. The performance of the valve is greatly influenced by the nonlinearity of the proportional solenoid, such as dead zone and low force gain with a small current, and this effect cannot be eliminated by a simple dead-zone current compensation. To avoid this disadvantage, we propose the differential control method(DCM). By employing DCM, the controller outputs differential signals to simultaneously energize both solenoids of the proportional valve, and the operating point is found by analyzing the force output of the two solenoids to make a minimum variation of the current force gain. The comparisons of the valve response characteristics are made between NCM and DCM by nonlinear dynamic simulation and experiments. Simulation and experimental results show that by using DCM, the frequency response of the valve is greatly enhanced, especially when the input is small, which means that the dynamic characteristics of the proportional valve are improved.

Dynamic performance and control accuracy of a novel proportional valve with a switching technology-controlled pilot stage

Two-stage directional valves usually employ proportional pilot control technology,which has the disadvantages of dead zones,leakage,and the large moving mass of the pilot valve.It is difficult,therefore,to achieve fast-response performance of the main valve.In order to overcome this problem,a switching pilot technology that employs two independent high-speed on/off valves(HSVs)is proposed to replace the traditional pilot proportional valve.Due to the rapid switching characteristics of HSVs,the dead zone of the pilot stage is avoided,and the dynamic response performance of the main valve is improved.The experiments indicate that the switching frequency of the pilot HSVs and supply pressure of the pilot stage have a very large effect on the dynamic performance and control accuracy of the main valve.Increasing the switching frequency of the pilot HSVs is helpful for improving main-valve control accuracy.The larger supply pressure of the pilot stage can achieve a faster dynamic performance of the main valve while causing larger static errors.The results show that the switching pilot technology can clearly improve the static and dynamic performances of the main valve.With the increase of pilot supply pressure,the step rise time is reduced from 21.4 ms to 16.8 ms,and the dynamic performance of the main valve is improved by 21.5%.With the increase of pilot switching frequency,the steady-state error decreases from 24μm to 20μm,and the control accuracy of the main valve is improved by 16.7%.

高压阀口液动力补偿控制策略仿真分析

直动式比例伺服阀是一种新型的单级伺服阀,采用比例电磁铁或线性力马达直接驱动滑阀运动,具有成本低、频响高、抗污染能力强等优点,广泛应用于注塑机进给控制、轧机板厚控制系统等高速高精度液压控制系统中。传统的直动式比例伺服阀采用PID控制策略实现阀芯的精确位置控制,在高压大流量工况下(供油压力达到20 MPa、流量大于100 L/min),阀芯受到液动力扰动变得更加剧烈,易出现响应速度慢、阀芯抖动的现象,影响了比例伺服阀的控制精度。为了解决大液动力扰动的问题,提出了一种基于指数收敛干扰观测器的滑模控制器。通过建立阀芯动力学模型来设计滑模控制器,保证阀芯位置的高动态跟踪性能;使用基于指数收敛的干扰观测器,估计阀芯动力学模型中液动力的不确定性扰动,解决高压大流量工况下的阀芯液动力扰动补偿问题。搭建了比例伺服阀系统的联合仿真模型进行仿真验证,结果表明,提出的控制器可以解决高压大流量工况下阀芯液动力扰动对阀芯位置控制的干扰问题。

基于PLC的IGCT测试夹具控制系统的研制

该系统以S7-200 SMART型的可编程逻辑控制器(PLC)为控制核心,配合使用压控恒流源、比例阀、压力传感器、温度控制器、安全光栅等其他硬件设施,可实现集成门极换流晶闸管(IGCT)测试夹具的动作控制、压力显示、测试及安全互锁等功能。对比例阀的控制信号进行了精确计算与仿真。基于STEP7软件平台,对PLC的主要软件程序进行了设计,将夹具的控制系统部署到IGCT器件的测试系统中去,经过三年多的现场实际应用,发现各项功能都能够实现且运行高效稳定,取得了良好的效果。

农业机械电液控制技术发展现状及展望

电液控制技术作为农业机械关键技术之一,对于增强机械性能、提升操作便捷性和提高生产效率具有显著影响。综述了农业机械电液控制技术发展现状,通过具体案例,展示先进电液控制元件及系统在提升农业机械整体性能,特别是在模块化订制、智能化控制、电驱高效节能等方面的作用和潜力。未来以人工智能和物联网为代表的先进技术将与电液控制系统相结合,进一步推动农业机械向智能化和无人化方向发展。

基于LabVIEW的比例压力控制阀自动测试系统

根据某公司比例压力控制阀的出厂测试要求,本文设计了一套比例控制阀自动测试系统。该系统基于LabVIEW编程和PLC控制,可实现共轨管稳定的超高压供给,并自动实现比例压力控制阀的耐久测试、流量滞环测试及压力-流量测试,且操作简便,满足企业需求。

比例阀控气缸系统确定性鲁棒反步运动跟踪控制器

为实现气缸运动轨迹的高精度鲁棒控制,建立了比例阀控缸系统的数学模型,并基于反步法设计了一种能够有效抑制系统模型参数不确定性、未建模动态和外界扰动等因素影响的非线性确定性鲁棒控制器。利用MATLAB中的Simulink模块构建气缸运动轨迹跟踪控制系统仿真模型。采用MATLAB/Simulink中的xPC-Target开发了基于非线性确定性鲁棒控制器的气缸运动轨迹实时控制系统。仿真结果表明所设计控制器是可行的。试验结果表明该控制器能够有效地跟踪参考轨迹,跟踪0.3 Hz正弦轨迹时的最大跟踪误差为0.89 mm,约为幅值的2.97%;跟踪0.4 Hz正弦轨迹时的最大跟踪误差为1.02 mm,为幅值的3.4%。

垂直冲击试验台同步及快速制动液压控制系统研究

为解决垂直冲击试验台负载质量大,且易产生二次冲击的问题,针对试验台液压控制系统的关键技术要求,设计了一种双液压缸位置同步控制系统和快速反弹制动系统。首先,根据试验台的关键技术指标,综合考虑了实际工况与经济性等因素,设计出了液压控制系统原理图;然后,针对同步控制系统,利用Simulink软件设计了模糊控制器及同步控制算法模型,同时利用AMESim软件搭建了液压系统仿真模型,并对两个模型进行了联合仿真,针对反弹制动系统,利用AMESim软件进行了建模和仿真;最后,对比了模糊PID控制与常规PID控制的仿真结果;设计制造了大型垂直冲击试验台,进行了实际测试,验证了仿真结果的正确性。研究结果表明:针对实际工况下模糊PID控制方式的同步误差最大为0.09 mm,满足0.2 mm的同步精度要求,采用模糊PID控制方式对比常规PID控制方式,其有较高的同步控制精度与较强的鲁棒性;采用比例伺服阀加插装阀驱动制动器,使工作台进入快速制动的工作模式,整体响应时间为63 ms,满足100 ms的制动生效时间要求;实际同步控制系统最大同步误差为0.11 mm,满足性能指标,验证了控制方案与仿真的正确性。

基于粒子群优化的模糊PID阀控液压缸控制仿真

为了提高比例阀控液压缸的控制效能和精度,针对比例阀控液压缸存在响应速度慢、跟踪精度低等问题,提出了一种粒子群优化(Particle Swarm Optimization,PSO)模糊PID参数的方法。建立AMESim-Simulink联合仿真平台,采用了基于粒子群优化的模糊PID控制算法,针对比例阀控液压缸系统,使用粒子群算法对模糊PID进行参数调优,并运用AMESim-Simulink联合仿真平台进行模拟实验。模拟实验验证了基于粒子群优化的模糊PID控制器提高了系统的响应速度,减小了超调量,提高了稳定性。

某型全自动变截面板簧轧机液压系统故障分析与排除

对某型汽车板簧轧机液压系统原理及工作全过程进行了分析,对机器生产现场出现的两类故障现象进行阐示:①压下缸推动上轧滚压下钢板时,压力不够。观看压下缸压力表此时只有7MPa,钢板压制的尺寸不到位,导致报废;②设备刚启动后,控制压力油路表3压力较低,把控制油的回油管(L管路)堵塞,压力就升上来,影响压下缸正常工作进行阐示,对这两种故障原因进行分析,并分别给出解决方案,现场排除了故障。

恒力磨床液压控制系统研究

为提高某恒力磨床设备的压力精度,增加对位置偏差干扰的抵抗能力,根据设备输出数据指标设计研究液压控制系统。根据设计的液压原理图在AMESim仿真软件中完成系统仿真建模,进行闭环压力控制系统分析研究,最终采用前馈补偿与压力闭环反馈结合的复合PID控制方案,具有最佳控制效果,并能够实现在工作过程中遇到位置偏差时具有一定抗干扰能力,保证输出精度在目标压力精度范围内。

静叶调节执行机构PLC控制系统设计

为准确及时调控风机静叶角度,设计一种基于电液控制技术的静叶调节执行机构。首先介绍静叶调节执行机构的液压系统,然后重点介绍PLC控制系统硬件结构和软件编程要点,通过增加积分项权值方法,改进经典PID控制方法的缺陷,提高系统的响应速度和稳定性。

变转速变排量双动力源泵阀协同电液系统特性分析

针对起重机阀控系统响应快但能耗大,泵控系统效率高但控制精度低的问题,提出了一种变转速变排量双动力源泵阀协同的多执行元件电液系统。首先,提出了一种多模式控制策略,即在单动作微动模式下,其中一个动力源卸荷,由于系统小流量时动态响应较慢,因此小流量时采用双变量模式控制系统,通过阀芯位置自适应调节和动力源的压力闭环控制,实现了流量精准匹配的目的;其次,在单动作快速运动模式下,双动力源合流驱动单执行元件,通过控制电液动力源相关参数,补偿了因负载变化引起的泵泄漏量,以实时控制执行元件速度;在复合快速运动模式下,双动力源分流单独驱动多执行元件,通过调节单个动力源的相关参数来实时控制各执行元件速度,以及实现系统流量比例分流的目的;然后,建立了系统AMESim-Simulink的联合仿真模型与试验平台;最后,对该系统在同一设定压差下的不同设定流量的控制特性进行了仿真和试验分析。研究结果表明:该系统能实现负载变化时对流量的补偿目的,并且该系统与定转速变排量泵阀协同液压系统相比,在单动作微动模式下的流量控制精度优化了约14.76%,动态响应时间减少了约0.12 s;在单动作快速运动模式下,流量变化减小了约6.21%,系统能耗降低约了13.94 kJ;在复合快速运动模式下,系统能耗降低了约50.31 kJ;同时,该系统比传统抗流量饱和负载敏感系统具有更好的流量稳定性。

液压调距在压延机上的应用

将四辊压延机从原来的机械式电动调距升级为液压调距,详细说明了电气主控系统的配置,硬件组态过程,测试校准,使用方法等。应用后,系统控制准确可靠。