关于中国液压工业的差距与优势——访张海平博士

近年来,随着我国工程机械、冶金设备、矿山机械和农林机械等主机行业的高速发展,液压元件的市场规模正在逐渐扩大,中国液压工业从规模和数量方面已跻身大国行列;但同时必须看到,高端产品一直被国外公司所垄断,造成主机行业在重要基础部件方面受制于人,这成了中国液压工业领域的锥心之痛。如何振兴中国液压工业,我国的液压技术与液压强国相比差距在哪?优势又在哪呢?带着这些思考,我刊编辑采访了长期在德国和中国液压工业领域工作的液压技术专家张海平博士。     

精密减压阀的研制

作为压力调节与保持压力稳定的元件—减压阀是任何气路系统必不可少的。国内普通减压阀的生产和使用已很广泛,但在输出压力调节精度高的场合,特别是工业过程、检验程序的控制与分析,检测仪表和气动自动装置等要求保持压力恒定的地方,就必须使用精密减压阀。国内目前现有的定值器、稳压器等输出压力一般在0.15MPa 左右,不能满足需较高输出压力场合的使用,为此我所与上海气动元件厂共同进行了研制。一、结构及其特点精密减压阀由调压、比较、放大、反馈、稳压等部分组成。见图1。阀芯工作状态时为虚线位置。它是在内部先导式减压阀的基础上引入喷嘴一挡板放大机构。利用喷嘴挡板的位移引起力的放大,使膜片两侧受力达到平衡,来维持输出压力的稳定。由于喷嘴挡板具有高灵敏度,因而精密型减压阀的输出压力精度     

3DRE比例减压阀及其应用

1　前言减压阀是用来降低液压系统中某一回路的压力,使其出口压力降低且恒定的减压阀为定值输出减压阀,简称为减压阀,对定值输出减压阀的要求是:不管入口压力如何变化,出口压力应维持恒定,且不受通过阀的流量变化的影响。二通比例减压阀广泛地应用在压力油单方向流经减压?..     

智能化薄膜减压阀的研究

介绍了智能化薄膜减压阀的结构、工作原理及控制程序。     

关于定差减压阀和差压减压阀

该文讨论了文献中所介绍的定差减压阀和差压减压阀结构与称呼问题 ,对其中容易产生混乱的现象提出自己的意见 ,希望对统一认识减压阀有所帮助     

气体减压阀特性曲线的计算

推导了设计逆向式气体减压阀时比较精确的通用特性曲线公式，并以计算实例做了试验验证，供优化设计气体减压阀时参考。     

三通型先导比例减压阀的研究

本文研究的三通型先导比例减压阀,采用“系统压力直接检测、反馈”的闭环控制原理和先导级与主级的“级间动压反馈”原理,主阀采用双可变节流边的结构,先导阀采用双可变先导液阻半桥结构。该阀具有优良的“快速性”、“等压力特性”和稳定性。     

耐磨减压阀阀芯的研究

煤气厂在生产过程中,煤浆的输送要求在高压力、高流量下进行。煤浆的流量和压力由减压阀来控制,而煤浆对减压阀的破坏非常严重。减压阀的破坏主要集中在阀芯上,减压阀阀芯遭煤浆冲刷等原因引起的损坏相当严重。为了延长阀芯的寿命,节约成本,提高生产效率,我校对此问题进行课题研究,希望能得到既耐用又实惠的减压阀阀芯。     

高层建筑消防给水分区与减压阀的应用

本文系统分析了高层建筑消防给水分区的原则、三种供水工况、四种基本分区形成、减压阀的性能和应用。并分析了减压阀内部水头损失与压降和减压阀自身水头损失的关系，提出了减压阀减压分区的串并联公式及其对阀后出水压力的影响，且提出了经验分区高度４０ｍ。     

一种新型结构的气动减压阀

本文介绍一种新型结构的减压阀。该阀的调节部分根据射流档扳原理制成。其主要性能指标较膜片式减压阀有所提高。     

一种定差减压阀的结构设计

该文设计了一种结构简单,安装方便,使用可靠的定差减压阀,介绍了它的结构、工作原理、设计计算及应用。     

某型减压活门试验装置的设计

阐述了某型减压活门的构造和原理,针对其检测技术要求,设计了某型减压活门试验装置,并对管路的工作原理和试验工装的使用进行了描述,最后依据减压活门检测技术要求阐述了试验装置的检测原理。     

介绍一种新阀——软溢流阀

SUN公司的德国分公司Zaehe博士，发明了一种全新型的溢流阀。它除了如普通溢流阀那样，可以限制系统压力外，还可以限制系统压力的上升速率，消除压力超调，从而降低机械部件的动态载荷。该阀设计成螺纹插装阀形式，使用SUN公司标准孔型，已获得专利保护。该文介绍其功能、工作原理、实测性能和应用。     

活塞式减压阀结构性能的分析与探讨

对活塞式减压阀的结构和工作原理进行了分析,提出并强调了减压阀静态减压性能的意义,同时介绍了几种改进型的活塞式减压阀结构。     

Dynamic behaviors of nonlinear fractional-order differential oscillator

The nonlinear dynamic behaviors of oscillators described by fractional-order differential are presented in this paper. The background of the research is based upon two engineering practices. First is that the visco-elastic behaviors of some advanced polymeric materials can be accurately modeled by the fractional calculus constitutive law. Second is that the influence of nonlinear visco-elasticity described by the fractional operator cannot be neglected in some cases such as the vibration with large displacement or large strain and thermo-visco-elastic coupled problems. The numerical scheme for solving the nonlinear equation of motion is developed. The results show that because of the introduction of nonlinear damping modeled by the fractional-order operator, the bifurcation and chaos of the oscillator appear in forced vibration. Furthermore, the fraction value of the fractional operator evidently affects the dynamic behavior of the nonlinear fractional differential oscillator. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Wei Zhang received his doctorate degree in Mechanics at Xi’an Jiaotong University in China in 1994. He went to the University Of Sheffield in the UK as an academic visitor from July 1986 to July 1987. He completed his post-doctorate study in Iwaki Meisei University in Japan through the support of the JSPS from May 1997 to June 1999. Dr. Zhang is currently a professor at the Department of Electronic Engineering of JiNan University in Guangzhou, China. Shao-kai Liao received his B.E. degree in Civil Engineering at JiNan University in Guangzhou, China in 2004 and his master’s degree in Engineering Mechanics at the same university in 2006. Mr. Liao was once a postgraduate student of Professor Wei Zhang, and he now works in an institute in Shenzhen City in China. Nobuyuki Shimizu received his B.S. degree in Mechanical Engineering at Yokohama National University and his master’s and doctorate degrees in Mechanical Engineering at University of Tokyo in 1968 and 1971, respectively. He went to the California Institute of Technology in California, U.S.A. as a visiting associate from October 1976 to September 1977. Dr. Shimizu is currently a professor at the Department of Mechanical and Power Engineering of Iwaki Meisei University in Japan.     

先导式减压阀动静态特性研究

介绍了气体先导式减压阀的工作原理,建立了减压阀阀芯节流数学模型,分析了减压阀静态特性和动态特性。     

Heat transfer rate of a closed-loop oscillating heat pipe with check valves using silver nanofluid as working fluid

This research investigated the effect of aspect ratios (evaporator length to inner diameter of capillary tube), inclination angles, and concentrations of silver nanofluid on the heat transfer rate of a closed-loop oscillating heat pipe with check valves (CLOHP/CV). The CLOHP/CV was made from copper tubing with an internal diameter of 2 mm. Two check valves were inserted into the tube. The tube had 40 meandering turns. The length of the evaporator was 50, 100, and 150 mm. The lengths of the evaporator, adiabatic, and condenser section were equal. The concentration of silver nanofluid was 0.25, 0.5, 0.75, and 1 %w/v, and the operating temperature was 40, 50, and, 60°C. It was found that the heat transfer rate of the CLOHP/CV using silver nanofluid as a working fluid was better than that the heat transfer rate when pure water is used because the silver nanofluid increases the heat flux by more than 10%. This paper was recommended for publication in revised form by Associate Editor Man Yeong Ha Sakultala Wannapakhe received her B.Eng. degree in Mechanical Engineering (Manufacturing) from Mahasarakham University, Thailand, in 2005. She then received her M. Eng. degree in Mechanical Engineering from Mahasarakham University, Thailand, in 2007. Sakultala Wannapakhe is currently a Ph.D. student in Energy Technology at Mahasarakham University, Thailand. Sampan Rittidech received his Ph.D. degree in Mechanical Engineering from Chiang Mai University, Thailand, in 2002. Dr. Sampan Rittidech is currently an Associate Professor at the Faculty of Engineering at Mahasarakham University in Thailand. Dr. Sampan’s research interests include heat transfer, heat pipe, and heat exchanger. Bopit Bubphachot received his Ph.D. degree in Engineering Mechanics and Energy from University of Tsukuba, Japan, in 2008. Dr. Bopit Bubphachot is currently an Lecturer at the Faculty of Engineering at Mahasarakham University in Thailand. Dr. Bopit’s research interests include Metal Forming (Fine Blanking Process), FEM Simulation in Metal Forming Process and Fatigue and Creep-Fatigue strength for Perforated Plate. Osamu Watanabe received his Ph.D. degree in Engineering from University of Tokyo, Japan, in 1981. Dr. Osamu Watanabe is currently a Professor at Graduate School of Systems and Information Engineering at University of Tsukuba, Japan. Dr. Osamu’s research interests include inelastic behavior, material strength in nuclear or thermal plants, code and standard for plant technology.     

基于AMESim的减压阀建模与仿真分析

根据减压阀的工作机能,运用AMESim提供的HCD液压元件设计库构建减压阀的仿真模型,依照阀的相关数据设置模型的各项基本参数,进行仿真。通过调节仿真模型的特定参数对减压阀进行性能分析,以验证模型的正确性,为减压阀的设计和选择提供了依据。     

气体减压阀的研制与试验

论述了一种船用新型气体减压阀的结构特点、设计计算和压力特性试验。