装载机工作装置电液比例先导控制模块设计

该文根据装载机工作装置电液比例控制系统的要求,建立了电液比例先导控制的系统原理图,分析了先导控制模块的构成,设计了模块的详细结构,并在专门设计的试验台及ZL60型装载机上进行了试验测试。试验结果表明,设计的先导控制模块达到了装载机工作装置的电液比例操纵控制要求。     

柳工ZL50C型装载机铲斗自行前倾的原因及排查方法

正1.故障现象我单位1台使用了400h的柳工ZL50C型装载机,当操作手操纵铲斗阀先导手柄,将铲斗置于收回状态,再将先导手柄置于中位后,出现铲斗自行前倾故障。2.结构及原理该型装载机工作装置液压系统主要由工作泵1、铲斗缸2、动臂缸3、多路换向阀4、先导阀5、转向泵6、先导泵7、压力选择阀8、滤油器9、液压油箱10、过载阀和补油阀11组成,如图1所示。     

减压阀式先导阀

本文介绍的减压阀式先导阀是借助于操纵手柄调节其调压弹簧予压缩量的一组定值输出式减压阀。借助于这种先导阀来控制液动换向阀,要比直接操纵手动换向阀省力得多。先导阀的输出压力与操纵手柄的摆角成比例,故可用来对弹簧对中的液动换向阀进行比例控制。此外,还可以用一个手柄同时控制两个不同的液动换向阀。本文介绍这种先导阀的结构与工作原理、基本计算、应用回路以及试制与试验情况。     

CLG856型装载机工作装置无动作原因分析

1.故障现象1台柳工CLG856型装载机工作时转向、制动、行走均正常,但无论操作动臂先导操纵手柄还是铲斗先导操纵手柄,其动臂和铲斗均无动作,初步分析可能是其工作装置液压系统出现故障。     

装载机供油阀工作原理及故障排查

厦工产XG955III型装载机的工作装置液压系统,采用先导操纵取代传统的软轴操纵,以控制分配阀主油路油液的流动方向,实现铲斗翻转和动臂升降动作。其操纵简单轻便,动作平稳,功率损失小,作业效率高。该液压系统主要由油箱、滤油器、液压泵、多路换向阀、先导阀、动臂缸、铲斗缸、散热器、供油阀和蓄能器组成。     

压力比例先导阀的研制及其应用

压力比例先导阀是目前液压技术发展中出现的一种新型元件,它能根据不同的输入信号而对液压系统中的操作元件产生比例的液压力,从而使系统中的流量按比例地变化。例如:用它操纵变量油泵的伺服油缸可以按比例改变油泵排量;用它控制液控换向阀可以按比例改变系统流量。     

主动先导级控制的电液比例流量阀建模与仿真

高精度电液比例流量阀是很多重大机械装备中电液控制系统的核心部件，但采用压差补偿器或流量传感器控制流量，会降低阀的通流能力，增加系统功率损失和发热。因此，提出利用电机驱动液压泵作为先导级，连接Valvistor主阀，构造新的高精度电液比例流量阀，使主阀流量与先导流量成正比，其无论压差大小、正负皆可输出稳定的先导流量，达到提高流量阀的低压可控性和动态响应特性的目的。建立了新电液比例流量阀的数学模型，并建立其AMESim模型，对该阀的静动态特性的影响进行计算仿真分析，为进一步优化新电液比例流量阀结构提供依据。     

装载机转斗阀阀芯不能自动回位故障排查及原因分析

正1.故障现象1台使用了12000h的雷沃FL936F型装载机,其配置软轴操纵装置的多路阀出现松旷渗油故障。更换非原厂的多路阀后,该装载机卸料磕斗时、松开转斗操纵手柄后,转斗阀软轴操纵手柄出现不能自动回到中位(即转斗阀阀芯不能自动回到中位)故障,收斗时也偶发此故障,影响该机正常使用。     

基于Labview的挖掘机多路阀综合测试系统开发

介绍了一个基于Labview的挖掘机多路阀全电液综合测试系统。根据相关多路阀测试标准要求以及挖掘机多路阀的特点完成测试系统的液压系统原理和数据采集控制系统的设计。系统采用电液比例技术完成液压系统的控制包括系统压力、流量、多路阀的动作以及负载模拟,并利用Labview软件完成测试系统软件设计实现数据的自动采集、处理、显示以及打印等功能,因此系统具有很高的自动化程度能有效提高挖掘机多路阀的测试效率。以完成的测试系统为基础对某挖掘机多路阀进行相关的测试试验,从结果表面设计的综合测试系统功能完善、操作简单。     

挖掘机斗杆液压回路工作原理及斗杆自行下降故障排查

<正>1.液压回路工作原理斗杆是挖掘机工作装置的一部分,其液压回路如附图所示。由发动机1输出动力给主泵的前泵2和后泵3以及先导泵4,使其输出工作压力油和先导压力油。驾驶员启动挖掘机后,打开安全锁操纵手柄,先导安全换向阀6阀芯移位,打开先导泵4到先导阀8的油路。当操纵先导阀8手柄执行挖掘动作时,先导压力油流经先导阀8后分为3路:第1路经过斗     

Modeling,simulation and experimental validation of flow rate of electro-hydraulic hitch control valve of agricultural tractor

Advances in non-linear control theory have made it possible to develop controllers for non-linear dynamic systems in their nature. The low-cost proportional control valves of the hydraulic control system are examples of such a system where there is no linearity due to the structure of the valves and the flaws in the spool. However, the non-linear analysis and regulation of these hydraulic systems cannot be done without a proper valve model. This paper presents a methodology for the development of an efficient unified model of a three-point hitch (TPH) electro-hydraulic proportional control valve control system for agricultural tractors by means of a parameter estimation technique. Modeling and simulation of the proportional control valve was performed using MATLAB Simulink software. Parameter estimation methodology was used to optimize the effective orifice opening of the solenoid valve to meet the flow characteristics available in the manufacturer's technical data sheet for the proportional control valve model parameters. Such unified Simulink models are useful for simulation, practical capability testing, and non-linear control design. Modeling and simulation of electro-hydraulic hitch (EHH) control valve were made and simulation results were compared with actual experimental results. The simulation results of the TPH lifting and lowering time were found to vary 4 and 12.5 %, respectively with the experimental results. This type of parameterized valve models facilitates their implementation in dynamic simulation models of complex hydraulic systems.     

先导式电液比例阀非线性位置自适应补偿控制

为了提高先导式电液比例阀的位置控制性能,解决大批量先导式电液比例阀生产带来的不一致性问题,首先,建立了比例阀的非线性数学模型,针对比例阀死区不一致且难检测的问题,提出死区在线检测方法,采集主阀开始运动时的先导阀电磁铁电流值来表征死区大小,将当前死区值通过上位机在线读出并进行补偿;然后,针对普通PID固定增益带来的控制效率和精度低下的缺点,设计了基于死区在线检测的模糊PID自适应位置控制器,实时动态调整控制器各项参数;最后,基于MATLAB软件和先导式电液比例阀测试平台,验证所提出的控制方法的有效性。研究结果为先导式电液比例阀的批量化生产奠定了理论基础。     

直动式高频响比例阀位置控制研究

为了提高比例换向阀的频响和位置控制精度,以直动式电液比例方向阀为研究对象,建立比例阀的非线性数学模型,并结合工程实际,分析比例阀的非线性特性.采用LVDT观测阀芯的位移变化,提出了一种基于前馈补偿的控制方法,并通过AMESim仿真验证该方法的有效性.该控制方法的提出将有助于提高电液比例阀的频响和控制性能,并进一步提升高...     

模糊PID进出口独立控制装载机摇臂液压系统

传统装载机常采用四边联动滑阀的多路阀控制液压缸运动,致使进出液压油口节流损失大,尤其对于负载复杂多变工况的摇臂液压缸,能耗损失更为明显。为改进这些不足,提出了一种基于模糊PID泵阀协同进出口独立控制的装载机摇臂液压系统。采用AMESim,LMS Virtual.Lab Motion仿真软件建立了原机的机液联合仿真模型,并通过试验验证了所搭建模型的准确性。在原模型的基础上,构建了基于模糊自适应PID泵阀协同进出口独立控制的装载机摇臂液压系统仿真模型,并进行了动力性、能效特性的研究。结果表明,采用进出口独立模糊PID控制方法可显著降低阀口节流损失,在保持摇臂机构动力性不变的前提下,泵功率峰值在摇臂油缸阻抗和超越工况下分别降低了13.6%和46.8%。     

二维电液比例换向阀动态特性及稳定性分析

二维电液比例换向阀兼具直动式和导控式比例阀的功能:正常工作压力下,比例电磁铁输出的推力通过压扭联轴器使阀芯转动,阀敏感腔的压力差动变化,驱动阀芯轴向移动,与此同时阀芯反向转动,敏感腔的压力又逐渐恢复为原来的值,阀芯到达一个新的平衡位置,实现对阀芯位移的液压先导比例控制;当工作压力为零时,则由比例电磁铁直接驱动阀芯。在正常的工作过程中,压扭联轴器不仅可以实现直线-旋转运动转换,还可将比例电磁铁的驱动力放大,使其能有效、可靠地驱动阀芯转动,从而提高其比例控制性能和工作可靠性。通过2D阀的建模、动态仿真及稳定研究,弄清2D阀的关键结构和工作参数对动态特性的影响,并建立2D阀的稳定条件,为其结构设计和优化提供理论依据。对2D阀试验研究,测得直动与导控两种工作状态下主要性能曲线与指标,试验表明2D电液比例换向阀不仅可以实现直动和导控的功能,而且通过先导控制可以有效克服液动力和摩擦力的不利影响,同时也证明了2D阀具有较快的响应速度和很好的稳定性。     

Robust control design for a wheel loader using and feedback linearization based methods

The heavy equipment industry is building more and more equipment with electro-hydraulic control systems. The existing industry practices for the design of control systems in construction machines primarily rely on classical designs coupled with ad-hoc synthesis procedures. Such practices produce desirable results, but lack a systematic procedure to account for invariably present plant uncertainties in the design process as well as coupled dynamics of the multi-input multi-output (MIMO) configuration. In this paper, two H_∞ based robust control designs are presented for an automatic bucket leveling mechanism of a wheel loader. In one case, the controller is designed for the base plant model. In another case, the controller is designed for the plant with a feedback linearization control law applied yielding improved stability robustness. A MIMO nonlinear model for an electro-hydraulically actuated wheel loader linkage is considered. The robustness of the controller designs are validated by using analysis and by simulation using a complete nonlinear model of the wheel loader linkage and hydraulic system.     

Simulation and control of an electro-hydraulic actuated clutch

The basic function of any type of automotive transmission is to transfer the engine torque to the vehicle with the desired ratio smoothly and efficiently and the most common control devices inside the transmission are clutches and hydraulic pistons. The automatic control of the clutch engagement plays a crucial role in Automatic Manual Transmission (AMT) vehicles, being seen as an increasingly important enabling technology for the automotive industry. It has a major role in automatic gear shifting and traction control for improved safety, drivability and comfort and, at the same time, for fuel economy. In this paper, a model for a wet clutch actuated by an electro-hydraulic valve used by Volkswagen for automatic transmissions is presented. Starting from the developed model, a simulator was implemented in Matlab/Simulink and the model was validated against data obtained from a test-bench provided by Continental Automotive Romania, which includes the Volkswagen wet clutch actuated by the electro-hydraulic valve. Then, a predictive control strategy is applied to the model of the electro-hydraulic actuated clutch with the aims of controlling the clutch piston displacement and decreasing the influence of the network-induced delays on the control performances. The simulation results obtained with the proposed method are compared with the ones obtained with different networked controllers and it is shown that the strategy proposed in this paper can indeed improve the performances of the control system.     

Deadzone compensation control based on detection of micro flow rate in pilot stage of proportional directional valve

The pilot operated proportional directional valves (POPDVs) with a flow rate ranging from 100 to 1000 L/min are widely used in electro-hydraulic systems (EHSs). The deadzone of the pilot stage valve and its control compensation could significantly affect the position control performance for the main stage valve that could directly affect dynamics of EHSs In this paper, it is concluded that micro flow rates exist at the intermediate position of the valve based on the analysis of the continuity equation of the flow in the control chamber of the pilot stage. The micro flow rate is helpful to eliminate the discontinuity and unsmooth domain in the previous inverse deadzone compensation function. An improved deadzone detection method is proposed to calibrate the pilot valve flow characteristics which include the micro flow rate. This new method avoids the threshold selection of the main valve spool displacement which affects the detected deadzone values. Its detection processes are realized based on the pilot flow rate characterized by the speed of the main valve spool and the pilot valve displacement characterized by the solenoid current. The deadzone compensation control strategy based on the improved deadzone detection method is also designed. The experimental results using the steady-state position tracking and sinusoidal position tracking methods are verified. It is concluded that the tracking accuracy of the main valve spool position is effectively improved with this control strategy.     

二通插装阀方向控制回路故障的分析与排除

二通插装阀在高压大流量的液压系统中应用广泛,将多个标准化的插装式元件组合使用便可实现不同的控制功能,针对冲洗泵站中一种二通插装阀方向控制回路在调试过程中出现的故障,从方向控制回路电液控制的原理出发,结合现场试验检测,应用液压回路故障树的分析方法对故障进行分析并找出故障点,最后找到这种二通插装阀方向控制回路故障的解决方法。     

新型矿用比例方向阀动态特性及控制方法分析

适用于液压支架的比例方向阀代替现有的开关型方向阀,是液压支架智能化的重要组成部分。提出了一款适用于液压支架系统的比例方向阀方案,其兼有手动开关控制模式和电液比例控制模式,建立了其数学模型和仿真模型,分析了其动静态特性。研究表明:主阀进液阀芯位移与输入信号占空比呈线性反比例关系;合理设计反馈槽宽度和进液阀芯面积比可以提高阀芯的响应速度;当仅有液压反馈时,进液阀芯位移仍受控于输入信号,避免了因传感器失效对控制系统造成的灾难性事故的发生;通过增加电反馈与原有液压反馈构成双反馈控制的方式,大幅提高了阀的响应速度、线性度、滞环等特性。