RESEARCH OF THE DYNAMIC CHARACTERISTICS ON A NEW HYDRAULIC SYSTEM OF ELECTRO-HYDRAULIC HAMMER

A new typed hydraulic system of electro hydraulic hammer is researched and developed By means of power bond graphs the modeling and simulation to the dynamic characteristics of the new hydraulic system are performed The experimental research which is emphasized on the blowing stroke is also performed It is proved from the result of simulation and experiment that this new hydraulic system possesses such advantages as simplification of structure,flexibleness of operation and reliability of working Especially it possesses better dynamic

Dynamic Simulation and Valve Structure Optimization of an Electro-Hydraulic Clutch Shift Control System in an Automatic Transmission

The electro-hydraulic clutch control system controls the transferred torque of gear-shifting clutches in clutch-to-clutch transmissions. A nonlinear dynamic model of an electro-hydraulic clutch shift control system is presented. The mechanical and fluid subsystems of all valves are investigated, including their interactions. Model validation of the electro-hydraulic valve system is performed by comparing the simulated and measured pressure curves. The dynamic characteristics of the electro-hydraulic clutch shift control system with different supply pressures and different fluid temperatures are simulated and evaluated. It is found that pipes which are often ignored between the electro-hydraulic valve system and the clutch piston,have strong influence on clutch piston chamber pressures. In order to satisfy the required time and reduce the fluctuation of the clutch piston chamber pressures,the orifices' diameters and valve structure are optimized.

DYNAMIC CHARACTERISTICS OF LARGE FLOW RATING ELECTROHYDRAULIC PROPORTIONAL CARTRIDGE VALVE

A kind of cartridge servo proportional valve is discussed,which can be used for controlling large flow rate with high performance.By analyzing the structure principle of the valve,the transfer function of the valve is derived.With the transfer function,some structure elements that may affect its performance are investigated.Through the numerical simulation and test study,some principles of optimality and effective methods for improving the dynamic performance of the valve are proposed. The test results conform to the results of the theoretical analysis and simulation,which proves the correctness of the study and simulation works.The paper provides theoretical basis for engineering applications and series expanding design works.

Dynamic characteristics of hydraulic power steering system with accumulator in load-haul-dump vehicle

Using hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle as a simulation example, the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle were simulated and discussed with SIMULINK software and hydraulic control theory. The results show that the dynamic characteristics of hydraulic power steering system are improved obviously by using bladder accumulator, the hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle generates vibration at the initial stage under the normal steering condition of pulse input, and its static response time is 0.25 s shorter than that without bladder accumulator. Under the normal steering working condition, the capacity of steering accumulator for absorbing pulse is directly proportional to the cross section area of connecting pipeline, and inversely proportional to the length of connecting pipeline. At the same time, the precharge pressure of nitrogen in steering accumulator should be 60%80% of the rated minimum working pressure of hydraulic power steering system. Under the abnormal steering working condition, the steering cylinder piston may obtain higher motion velocity, and the dynamic response velocity of hydraulic power steering system can be increased by reducing the pressure drop of hydraulic pipelines between the accumulator and steering cylinder and by increasing the rated pressure of hydraulic power steering system, but the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle have nothing to do with the precharge pressure of nitrogen in steering accumulator.

DYNAMIC CHARACTERISTICS OF ELECTRO-HYDRAULIC PROPORTIONAL PRESSURE-FLOW HYBRID VALVE

在流动和压力工作条件下面的结构原则被学习，以便调查电镀物品水力的比例的压力流动混血儿阀门的动态特征。根据在二个不同工作条件下面的结构原则，在如此的条件下面的转移功能被导出。与转移功能，一些组织可以影响它的表演的元素，被调查，以后， optimality 的一些原则和为改进阀门的动态表演的有效方法被建议。结论能被用来指示工程应用和产品设计。测试结果遵循理论分析和模拟的结果，它证明学习和模拟工作的正确性。

Dynamic impact experiment and response characteristics analysis for 1:2 reduced-scale model of hydraulic support

It is significant to research the impact resistance properties of hydraulic support due to its key support role in the fully mechanized mining face.However,it is difficult for the entire hydraulic support to implement the impact experiment underground and analyze the response characteristic.Therefore,a dynamic impact experiment for the entire hydraulic support was proposed in this paper,where a 1:2 reducedscale model of hydraulic support was designed and its response characteristics under dynamic impact load were analyzed.Firstly,a comprehensive monitoring scheme was proposed to achieve an effective monitoring for dynamic response of hydraulic support.Secondly,a multi-scale impact experiment was carried out for the entire hydraulic support and dynamic behaviors of hydraulic support under the multi-scale impact load were revealed by experimental data.Then a dynamic impact experiment of the entire hydraulic support was simulated in ADAMS with the same experiment conditions,and the experimental and simulation data were verified mutually.Finally,the characteristics of energy conversion and dissipation of the entire experiment system after impact were analyzed.The experiment results showed that the impact resistance properties of hydraulic support largely depended on the initial support conditions and different vertical rigidities affected energy distribution proportion of the entire support system.

Analysis on Static Pressure Bearing Seal Characteristics of Guide Sleeve of Electro-hydraulic Servo Cylinder

As a typical bionic walking robot, hydraulic quadruped robot has attracted much attention because of its high mobility, strong load capacity and steady motion. The electro-hydraulic servo cylinder, as its power actuator, requires low friction, good lateral load resistance and high speed motion. The electro-hydraulic servo cylinder hydrostatic bearing seal guide sleeve is taken as the research object in this paper. By using Fluent software to analyze and contrast the film characteristics of rectangular and I-shaped oil chamber of hydrostatic bearing seal guide sleeve, the relationship between piston rod moving speed, eccentricity, oil film carrying capacity, friction force and leakage volume, as well as the relationship between oil feed flow and oil film bearing capacity, friction force, inlet pressure and leakage volume were analyzed. This study provides a theoretical basis for optimizing the static pressure bearing seal parameters.

Separate Control of High Frequency Electro-hydraulic Vibration Exciter

The working frequency of the conventional electro-hydraulic vibration exciters,which consist of a servo valve and a hydraulic cylinder,is generally restricted within a narrow range due to limited frequency response capability of the servo valve itself.To counteract such restriction,a novel scheme for an electro-hydraulic vibrator,controlled by a two-dimensional valve(2D valve) and a bias valve in parallel,is therefore proposed.The frequency,amplitude and offset are independently controlled by rotary speed,axial sliding of the spool of the 2D valve and axial sliding of the spool of the bias valve.The principle of separate control was presented and the regulation approach of frequency,amplitude and offset was discussed.A mathematical model of the hydraulic power mechanism for the proposed vibration exciter was established to investigate the relationship between the amplitude and the axial sliding of the 2D valve' spool,as well as that between the offset and the axial sliding of the bias valve's spool at various frequencies.An experimental system was built to validate the theoretical analysis.It is verified that the 2D exciter is capable of working smoothly in a frequency range of 5- 200 Hz.And its frequency,amplitude and offset can be controlled respectively by either closed loop or open loop method.There is a linear relationship between the output amplitude and the spool axial opening of the 2D valve until a point when the flow rate becomes saturate and the amplitude remains constant.The offset displacement of the cylinder's piston is linearly proportional to the axial displacement of the spool of the bias valve,when the valve opening is less than 25%.Thereafter,the slop of the offset curve decreases and tends to saturate.The proposed electro-hydraulic vibration controlled by the 2D valve not only facilitates the realization of high-frequency electro-hydraulic vibration,the high-accuracy of vibration can also be achieved by means of independent controls to the frequency,amplitude and offset.

Dynamic simulation of hydrokinetic hammer based on virtual prototyping technology

This study presented the specified steps of comprehensively analyzing the hydraulic-driven hammer system with the application of the Virtual Prototype Technology.By comparing the simulation results with experimental phenomena and data,the correctness of simulation analysis conclusion is verified.Meanwhile,by means of its perfect visualization,the internal work process which can not be seen before is simulated.The mechanism of some abnormal phenomena encountered during the experiment is explained.

基于ADAMS/Hydraulics的减振器设计与特性仿真研究

为深入研究高速列车车辆减振器的性能,更好地改善高速列车的舒适度,建立了高速列车电液比例阀式减振器的数学模型,并通过ADAMS软件的Hydraulics模块对该减振器进行动力学仿真,得出减振器的示功图以及阻尼随速度变化的特性曲线。仿真结果表明:此减振器的阻尼力与阻尼口的开口大小及振动频率有关,同时其可以连续变化,能够满足半主动减振器可调可控的要求。

灯泡贯流式水轮机增减负荷动态特性分析

水轮机频繁经历变负荷工况转换过程,使得机组在较短时间内工作参数急剧变化,严重影响电站稳定运行。该研究以某贯流式水轮机为研究对象,在考虑自由液面和水体重力的情况下,采用动网格技术对贯流式水轮机相同出力范围下的减、增负荷过渡过程的动态特性进行分析。研究结果表明:由于增负荷和减负荷过渡过程的起始工况导致起始流动状态不同,因此在相同出力时,机组内的流动分布不同,减负荷过程尾水管内的涡流面积及强度明显小于增负荷工况,且尾水管涡带尺度也明显小于增负荷过程;相比于增负荷过程,减负荷过程中转轮叶片大范围的低压区极易引发空化;机组内的水压力脉动主要以尾水管涡带引起的0.1f_n(f_n为转频)低频压力脉动和转轮的旋转引起3f_n的高频压力脉动为主,增负荷过程的压力脉动幅值明显大于减负荷过程,两种压力脉动共同作用,使得贯流式水轮机主要振动区域集中于转轮。研究结果对贯流式水轮机的设计与运行具有一定的指导意义。

某水下打桩锤主控阀缓冲装置建模与仿真

为研究某水下打桩锤缓冲装置的结构对主控阀缓冲性能的影响,介绍缓冲装置的结构组成和缓冲原理,考虑液压油泄漏导致主控阀腔内压力和温度的变化,结合热力学和流体动力学理论建立缓冲装置的动态数学模型,基于MATLAB/Simulink软件搭建仿真模型并进行仿真分析,研究液压系统回油背压、缓冲腔直径、泄漏缝隙高度和长度等参数对缓冲性能的影响规律。结果表明:打桩锤主控阀缓冲装置的泄漏缝隙高度、泄漏缝隙长度和缓冲腔直径对缓冲性能的影响显著,液压系统的回油背压影响相对较小。研究结果为主控阀缓冲装置的设计和结构参数的优化提供理论依据。

机液反馈式偏转射流压力伺服阀机理及特性分析

电液压力伺服阀是飞机刹车压力伺服系统的重要控制元件。为满足压力伺服阀高动态和高可靠性的要求,设计了一种机液反馈式偏转射流压力伺服阀。为研究该压力伺服阀的工作机理和静动态特性,建立了其数学模型和Simulink仿真模型。通过仿真结果可知,压力伺服阀的死区电流为1 mA,最大输出压力为10 MPa,压力增益为1.15 MPa/mA,幅频宽为26 Hz,相频宽为36 Hz,动静态性能良好,满足系统要求。通过实验对理论、仿真模型的准确性进行了验证,验证结果表明,理论模型能较好地预测压力伺服阀的静态性能,为压力伺服阀的结构设计和优化提供理论支撑和仿真参考。

推摇式油茶果采摘机构液压系统动态特性研究

为实现油茶果采摘机械化,文中自主研发了一款推摇式油茶果采摘机。介绍了该油茶果采摘机构的结构和工作原理,设计了油茶果采摘机构的液压系统原理图,并以采摘机构液压系统中的振动回路为研究对象建立数学模型并进行参数计算,采用AMESim软件进行建模仿真。结果表明:振动回路系统稳定流量为100 L/min,对应马达稳定转速为1700 r/min,振动马达工作压力为6.5 MPa,输出转矩为60 N·m,满足推摇式油茶果采摘机构的作业要求,且当原动机转速在1500~2500 r/min范围时,转速越高,振动马达振荡环节波动幅值越小,其超调量也越小,系统更加稳定,最小超调量为0.75%。

基于联合仿真的起竖系统动特性研究

为了对起竖装置的动态性能进行优化,对一种气液联合大流量油源快速起竖系统起竖过程动态特性进行研究。对起竖液压系统原理进行分析,并对起竖机构进行运动学及动力学分析,用有限元分析软件及动力学仿真软件建立起竖系统刚柔耦合多体动力学模型,并建立起竖液压系统模型及控制系统模型,基于软件接口实现机械、液压、控制系统的多学科联合仿真,并对仿真关键影响参数进行对比分析,研究其对起竖性能的影响。仿真结果验证了所建立模型的有效性,并为起竖系统的参数优化、控制方法研究等方面奠定基础。

电液混合驱动大惯量回转系统特性与能效分析

为了解决大惯量回转系统频繁启动和制动作业导致节流损失大和制动动能浪费严重的问题,提出一种电气和液压混合驱动大惯量回转系统。系统采用永磁同步电机作为主动力源,控制回转系统运动;由蓄能器提供动力的液压马达作为辅助动力源,为电机启动加速提供扭矩补偿,蓄能器高效回收制动动能再利用。建立多学科联合仿真系统模型,基于主辅动力源合理供给原则,设计全周期工况识别速度控制策略,搭建电液混合驱动回转试验平台,对回转系统的特性和能效进行分析。研究结果表明,电液混合驱动大惯量回转系统,随着转速和转动惯量的变化,回转制动动能回收效率为40.5%~65.9%。相同工况下,与纯电机驱动系统相比,电液混合驱动系统启动加速时间减小1.2 s,制动动能回收效率为63.5%,降低系统能耗40.8%,使回转系统更加平稳地运行。

基于AMESim的智能综采工作面电液控制系统的仿真研究

以智能综采工作面电液控制系统为研究对象,介绍该系统的工作原理,分析五柱塞乳化液泵、卸载阀、电液换向阀组的工作原理和结构特点,建立关键元件的数学模型。基于AMESim仿真软件,构建系统关键元件的仿真模型,对不同工况状态下的系统进行仿真,分析卸载阀关键结构参数对系统压力特性的影响。结果表明:仿真模型准确,液压系统性能良好,乳化液泵的流量仿真结果与传统计算方法数值吻合,卸载阀不同阻尼孔参数对系统压力特性影响效果不同。

挤压力对干法制粒机挤压辊运行特性分析

干法制粒机液压系统多采用普通电磁阀控制,即使采用了电液比例阀,也未形成闭环控制。针对此问题,基于电液比例技术对200型干法制粒机液压系统进行改进设计。依据挤压辊颤振力学模型,推导其竖直方向运动微分方程。利用AMESim和ADAMS软件构建机液联合仿真模型,研究不同的挤压成型压力对挤压辊运行特性的影响规律。结果表明:挤压辊运行特性较为平稳,挤压成型压力对位移特性的影响可以忽略不计;在系统启动瞬间,挤压辊速度和加速度波动峰值达到最大值;适当增大挤压成型压力,可有效改善挤压辊的速度和加速度波动特性;挤压成型压力对角加速度的影响要大于对角速度的影响。

基于递推最小二乘法的阀控缸液压系统控制策略

阀控缸液压系统存在建模不准确、动态控制精度较低和控制算法调试困难的问题,为此,提出了一种基于递推最小二乘法(RLS)的反步法动态面控制策略,并采用半实物仿真平台对其控制算法进行了调试验证。首先,建立了阀控缸液压系统非线性状态空间模型,推导了该系统的最小二乘矩阵形式和递推算法公式;然后,基于李雅普诺夫稳定性理论和动态面控制技术,建立了阀控非对称缸系统的控制模型,设计了一种基于RLS的反步法动态面控制器;最后,基于半实物仿真平台,对改造后的Linux操作系统进行了实时性验证,完成了阀控非对称缸系统参数辨识和基于RLS的反步法动态面控制试验任务。试验结果表明:RLS算法不仅能用于准确地估计系统模型参数,更能有效地适应系统模型参数的变化;相比于常规PID控制方法,基于RLS反步法动态面控制策略在阀控非对称缸系统稳定状态和换向的过程中,其动态控制精度分别提高了72.9%和20.3%,可为今后阀控缸液压系统建模及非线性控制策略研究提供较高的理论参考。

船闸顶扩廊道阀门段水力特性模拟研究

通过建立船闸整体输水系统三维数学模型,采用动网格技术及用户自定义函数(UDF)实现平面输水阀门匀速开启过程,分析顶扩廊道阀门段水流流态、流速及压力的动态变化规律。将数值计算的闸室水位、流量和廊道特征点压力与物理模型实测结果进行比较,二者吻合较好,说明了该数值模拟方法的可行性。数值模拟结果表明:阀门开启过程中,在阀门后形成大范围的逆时针漩涡,流速、紊动能及紊动耗散率随阀门开启先增大后减小,压力先减小后增大;当输水廊道阀门开启时间为4 min时,最小压力出现在阀门开度0.4时廊道的顶部;在该廊道体型及水力条件下,当阀门开启时间为5 min时,廊道后的时均压力最小。