空气弹簧液压悬置动特性及隔振特性研究

研究了具有可变刚度阻尼的发动机空气弹簧液压悬置的动特性和隔振特性。针对影响发动机空气弹簧液压悬置动特性的关键参数上液室等效体积刚度,采用理论和试验方法研究了上液室等效体积刚度的等效值,基于该等效值建立了空气弹簧液压悬置的理论模型,对空气腔开闭两种工况进行了空气弹簧液压悬置动特性的仿真和试验研究。搭建了发动机空气弹簧液压悬置系统试验台架,研究了台架各种激励频率下的空气弹簧液压悬置的隔振特性。结果表明:本研究采用的上液室等效体积刚度进行空气弹簧进行建模是正确、可行的,提高了空气弹簧建模效率和准确性;空气弹簧液压悬置在空气腔开启和关闭两种状态下,峰值动刚度增大幅值达78.5%,峰值阻尼角增大幅值达250%。台架试验表明:当台架激励频率小于25Hz时,悬置采用大刚度大阻尼;当台架激励频率大于等于25 Hz时,悬置采用小刚度小阻尼;悬置隔振率提升明显,不同频率下提升幅值达10%～67%。     

液压系统弹簧刚度动态变化下的压力冲击余弦级数研究

分析了油液含气量和液压缸活塞位移对液压油的有效体积弹性模量和液压缸等效动态弹簧刚度的影响,利用余弦级数计算出压力冲击的作用时间,并利用AMESim仿真软件验证所求时间的准确性。在此基础上利用动量定理推导出了压力冲击的计算公式,并求出了压力冲击的数值大小。研究结果表明,液压缸的等效动态弹簧刚度和油液中的含气量是影响压力冲击数值大小的主因,因此在设计液压系统时,可以降低油液中的含气量,提高液压缸的等效动态弹簧刚度来确保系统的稳定。以国内某钢厂的全液压双边滚切剪作为实验对象,由于数据采集的时间间隔为0.5 s/次,在出现压力冲击的时候数值没采集到,但是通过现场油管爆裂来看是有冲击产生的。通过分析理论推导与所采集到的压力冲击的大小,得出误差在11.12%左右,验证了理论推导的正确性。     

微位移控制液压系统建模与模型辨识

为实现微米级别位移控制,采用伺服驱动器、交流永磁同步电动机和位移放大液压缸代替传统伺服阀和泵源,利用位移放大液压缸与执行液压缸的有效面积比,对执行液压缸进行精确定位。针对其液压系统进行数学建模,讨论液压油弹性模量、油液黏度、蓄能器压力与体积等变量对系统动态性能的影响。建立微位移控制系统AMEsim仿真模型,仿真结果表明：液压油弹性模量越大,系统响应越快;油液黏度越大,系统响应越慢;蓄能器压力与体积对系统响应影响微小,仿真结果与数学模型预测相符。设计试验台并在试验台进行液压系统开环扫频特性试验,使用Matlab辨识工具箱对系统试验数据进行模型辨识,辨识结果表明：二阶系统与试验数据的吻合度较高,与数学模型预测相符。基于辨识模型设计的PD控制器在微位移控制综合平台上得到了应用,位置控制偏差范围为-2~1.7 μm。     

基于AMESim的长江船闸液压启闭机液压系统中插装式平衡阀稳定性分析

以长江船闸液压启闭机液压系统为对象进行研究,利用AMESim软件搭建该液压启闭机液压平衡回路仿真模型,并对整个船闸开启过程和关闭过程中插装式平衡阀内主阀芯弹簧刚度等主要参数进行单因素仿真。利用统计学分析这些单因素参数对长江船闸液压启闭机液压系统稳定性的影响。基于L₂₅(5⁴)正交试验,采用方差和极差分析法处理液压缸运行的压力曲线,得到选择范围内最佳的参数组合。结果表明：平衡阀内控制阻尼孔和主阀芯刚度等主要参数对液压缸运行压力和速度平稳性会产生重要影响,且通过正交试验可知较优参数组合为：阻尼孔尺寸0.71 mm,主阀芯弹簧刚度402 N/mm,主阀芯弹簧预紧力60 N,单向阀芯弹簧刚度3.87 N/mm。为螺纹插装式平衡阀的设计及液压启闭机液压系统参数优化提供指导。     

Stewart平台的综合谐振频率研究

载人的大惯量Stewart平台,多采用液压伺服系统驱动,其必然存在液压-机械综合谐振问题。这是由于油液的可压缩性、传动铰链的弹性及负载惯性等引起的。本文首先根据力-变形关系推导出Stewart平台的刚度矩阵,然后分别根据铰链和液压缸各自组成构件的串并联关系,推导出三维万向铰链和液压弹簧刚度的数学模型。进而建立了液压Stewart平台的无阻尼动力学方程,并据此研究了系统的综合谐振频率。理论计算与实验结果表明,平台的位姿、油液与铰链的刚度等因素决定了系统的综合谐振频率。     

双活塞杆液压缸动态性能参数影响因素的研究

论文以设计的双活塞杆液压缸为研究对象,建立了液压缸的数学模型,分析得到液压缸的动态性能参数固有频率和阻尼比与液压缸的等效质量、负载客积和液压介质的弹性模量等因素有关.研究了活塞杆伸出过程中,液压缸固有频率和阻尼比动态性能参数值的变化,对阀控缸系统和容积式调速回路系统的数学建模和分析有重要的参考价值.     

液压平衡回路动态特性仿真分析及实验研究

以一种液压举升系统的平衡回路为研究对象,根据实际工况,对平衡液压缸负载、平衡阀弹簧刚度及预紧力、控制阻尼孔大小等主要结构进行参数计算。运用AMESim仿真软件建立液压平衡回路的仿真模型,设置相关仿真参数并进行动态特性分析。设计了试验回路,对仿真的平衡回路进行台架试验,验证仿真分析的正确性,得出适当调整弹簧刚度、阻尼孔等结构参数可提高液压平衡回路工作性能,为液压平衡回路的优化设计及参数匹配提供借鉴。     

某试验机高频伺服液压缸设计与分析

以某试验机技术指标为基础,按其技术要求来设计高频伺服液压缸。通过建立高频缸系统AMESim模型,并进行仿真,分析了活塞组件的质量、活塞宽度、活塞与缸筒配合间隙、油液容积对高频伺服液压缸位移响应的影响,结论对高频伺服液压缸的设计具有一定的参考价值。     

基于反馈与前馈的二自由度电液振动台复合控制

为提高电液位置伺服系统控制精度,以电液振动台为控制对象,针对电液伺服系统液压固有频率较低、阻尼比较小等特点,提出一种三状态反馈控制与前馈逆模型控制相结合的二自由度复合控制策略。利用加速度反馈和速度反馈分别提高位置闭环系统的液压动力机构的阻尼比和液压固有频率,以保证系统在稳定条件下拓展系统工作频率范围;前馈逆模型控制能够改善实验系统的动态响应特性,进一步拓展系统频宽,提高电液振动台波形复现精度。实验结果验证了提出的二自由度控制策略的有效性。     

机载智能液压泵的建模与仿真

介绍了机载智能液压泵的结构、工作原理 ,对液压泵变量调节系统进行了数学建模和仿真。结果表明 ,斜盘位移响应的上升时间小于 2 2 ms,超调小于 8%,静态精度小于 0 .7%,变量机构平衡弹簧的最佳预压缩力相当于伺服阀供油压力的 1 /2 ,液压泵排油压力对变量调节响应时间的最大影响为 2 ms,液压油体积弹性模量取值的变化对变量调节没有明显影响 ,但伺服阀的恒定供油压力必须保证。     

磁流变伺服阀的设计与动态特性研究

利用磁流变液体可控的特性,设计了一新型伺服阀--磁流变伺服阀,介绍了该阀的结构特点及工作原理,建立了由该阀构成系统的数学模型并进行了理论分析.分析表明,与传统液压控制系统相比,由磁流变伺服阀控制的系统更易获得反应速度快、稳定性高、精度高等动态特性,能满足一般小功率、低压系统控制系统的要求.     

液压驱动单元力控系统建模及其性能影响因素研究

以四足机器人关节驱动器 液压驱动单元为研究对象,依据液压驱动单元的结构组成原理,采用机理建模的方法,建立其力控系统数学模型,该模型包含了基于辨识得到的伺服阀三阶传递函数、伺服阀的压力 流量非线性环节、伺服缸两腔容积变化因素等。建立液压驱动单元力控系统框图,并利用MATLAB/Simulink平台建立其仿真模型,采用实验测试与仿真分析相结合的方法,研究不同工作参数和不同给定信号下的液压驱动单元力控性能。研究结果表明：比例增益、供油压力、力阶跃量及正弦频率等参数均会对液压驱动单元的力控性能产生影响,该研究工作对四足机器人各关节高性能的力控方法研究提供了理论和实验基础。     

立体车库过放液压缓冲系统研究

提出并设计了立体车库过放液压缓冲系统,选型计算了系统关键元件参数,基于AMESim搭建了过放液压缓冲系统仿真模型,得到了载车板速度位移和缓冲缸压缩腔压力流量动态性能曲线,分别研究了不同溢流阀弹簧预压缩量和刚度对缓冲缸压缩腔及载车板位移的影响。仿真结果表明：该系统能有效吸收载车板过放能量;在不发生撞缸的条件下,减小溢流阀弹簧刚度和预压缩量有助于降低缓冲缸压缩腔压力冲击和提高缓冲缸吸能量。     

动压缸电液伺服压力系统自适应差分进化辨识

根据轨道路基测试装置工作原理,建立了动压缸电液伺服压力系统AMESim模型,理论推导出该系统传递函数。针对标准差分进化算法早熟问题,构造了一种可以自动调节变异因子、变异算子和交叉因子的自适应差分进化算法。设计了基于该系统AMESim模型的参数辨识方案,进行了自适应差分进化算法与其他算法的对比仿真,验证了该算法具有良好的辨识精度和收敛性,给出了动压缸负载开环传递函数辨识参数,并通过自适应差分进化算法获得了伺服阀系统开环传递函数辨识参数。最后给出了动压缸电液伺服压力系统传函参数,通过与该系统AMESim模型对比仿真,验证了该辨识参数的有效性。     

Development of new model of mold oscillator in continuous casting

To develop the hydraulic mold oscillator in continuous casting machine, the guiding mechanism of mold was studied. The main topics of this study were to design the guiding mechanism of mold which oscillates to prevent the sticking and to reduce the friction resistant force between the solidified shell and mold on casting. We studied many guiding types to analyze the features of worldwide mold oscillator and developed the new model of hydraulic mold oscillator. On the basis of the mold oscillating experiment, the capability of guiding system was proofed by the position error measuring system. The experiment was carried out up to 50–500 cpm frequencies and 2–10 mm stroke in the variable waveform and the casting results was analyzed by the oscillation mark of slab surface which was formed unavoidably by oscillation.     

Caster with non-sinusoidal profile for use in mold oscillator

The prototype of mold oscillator that uses a non-sinusoidal generator was modified using Inverse dynamics and Multi-body dynamics. We maintained a basic structure of the mold oscillator including the motor, the gear, the leaf-spring and the caster. To reduce the coupling effect, the non-sinusoidal generator was replaced by a hollow cylinder that had non-sinusoidal surface. The system parameters were obtained from previous research [1], and a new design of the connecting rod between the cylinder and the leaf spring was analyzed by sensitivity analysis. A definition of the detailed system component including gear mesh, and non-sinusoidal surface, Lagrange's equation, Fourier series, and Cam profile synthesis was used to define an equation of motion. The response of oscillating system was derived by a direct integration method. The model was simulated according a specific assumption for each component, and a control system corresponding to real operation was applied. Dynamic responses are displacement, velocity and acceleration of each component. All responses from these simulations were analyzed in the time-frequency region by Fast Fourier transform. Using the model, sensitivity analysis about design variables was also executed about operating performance.     

Decoupling analysis for a powertrain mounting system with a combination of hydraulic mounts

The existing torque roll axis(TRA) decoupling theories for a powertrain mounting system assume that the stiffness and viscous damping properties are constant. However, real-life mounts exhibit considerable spectrally varying stiffness and damping characteristics, and the influence of the spectrally-varying properties of the hydraulic mounts on the powertrain system cannot be ignored. To overcome the deficiency, an analytical quasi-linear model of the hydraulic mount and the coupled properties of the powertrain and hydraulic mounts system are formulated. The influence of the hydraulic mounts on the TRA decoupling of a powertrain system is analytically examined in terms of eigensolutions, frequency, and impulse responses, and then a new analytical axiom is proposed based on the TRA decoupling indices. With the experimental setup of a fixed decoupler hydraulic mount in the context of non-resonant dynamic stiffness testing procedure, the quasi-linear model of the hydraulic mount is verified by comparing the predictions with the measurement. And the quasi-linear formulation of the coupled system is also verified by comparing the frequency responses with the numerical results obtained by the direct inversion method. Finally, the mounting system with a combination of hydraulic mounts is redesigned in terms of the stiffness, damping and mount locations by satisfying the new axiom. The frequency and time domain results of the redesigned system demonstrate that the torque roll axis of the redesigned powertrain mounting system is indeed decoupled in the presence of hydraulic mounts (given oscillating torque or impulsive torque excitation). The proposed research provides an important basis and method for the research on a powertrain system with spectrally-varying mount properties, especially for the TRA decoupling.     

液压驱动6自由度运动模拟器动力机构控制策略研究

目前,非对称缸动力机构作为驱动部件被广泛应用于液压驱动6自由度运动模拟器,其控制器设计备受关 注。首先推导出了阀控非对称缸动力机构的通用非线性数学模型,在此基础上提出了级联负载压力控制策略,使 得动力机构具有力发生器的特性,从而为进一步实现运动模拟器的分层控制打下了基础。对于每个非对称缸电液 位置伺服系统,考虑到模型不确定性及外干扰的存在,运用滑模变结构控制方法设计外层镇定控制器,实现了对 液压动力机构的镇定及对外界干扰的抑制。同时作为比较,还设计了状态反馈控制器。仿真结果表明提出的控制 策略是有效的、合理的。     

连铸结晶器液压振动停振现象的探讨

武汉钢铁（集团）公司第一炼钢厂方坯连铸机结晶器振动装置采用的是目前国际上比较先进的液压振动技术，但使用中一直存在着突发性的停振现象，本文对产生停振的原因及解决对策进行了深入的分析与探讨。     

Frequency-dependent damping model for the hydroacoustic finite element analysis of fluid-filled pipes with diameter changes

The integration of a model for longitudinal hydroacoustic fluid damping in thin hydraulic pipes in 3D finite element models is presented in this paper. In order to perform quantitative prediction of the vibroacoustic behavior and resulting noise levels of such fluid-structure coupled system due to hydraulic excitation, an accurate frequency-dependent fluid damping model including friction effects near the pipe wall is required. This step is achieved by matching complex wave numbers from analytical derivation into a parameterized damped wave equation and consecutive translation into finite element modeling.Since the friction effect close to the pipe wall changes locally with the inner pipe radius, the fluid damping model is applied segment-wise in order to model the influence of cross-sectional discontinuity, such as orifices, on the oscillating pressure pulsations. A component synthesis approach, which uses pipe segments as substructures, allows a simple model generation and fast computation times.The numerical harmonic results are compared to experimental frequency response functions, which are performed on a hydraulic test bench driven by a dynamic pressure source in the kHz-range.