基于CFD的电液比例阀液动力分析

对电液比例阀的流场特性进行CFD计算,研究电液比例阀阀腔内部轮廓的变化对电液比例阀流场特征参数的影响.电液比例阀3种腔室结构的对比分析表明,作用于电液比例阀阀芯上的液动力能够通过优化其阀芯和阀套的结构而得到减小.     

拖拉机电液比例提升阀静态特性仿真与试验

电液比例提升阀由定差溢流阀和二位三通比例节流阀组成。定差溢流阀使节流阀两端压差稳定,从而稳定提升阀的输出流量。在对比例提升阀建立静态仿真模型时,由于定差溢流阀与节流阀的阀芯节流口形状和流动状态较复杂,使用传统的液动力公式难以准确计算阀芯所受的稳态液动力,从而影响阀的静态性能计算精度。为了准确地通过计算获得比例提升阀的静态特性,采用Fluent软件进行流场仿真计算节流阀与定差溢流阀在不同阀口开度和压差下的稳态液动力数值,并对其进行插值处理得到阀口稳态液动力与阀口开度、压差之间的插值模型,再代入仿真模型中解得比例提升阀的静态性能。试验结果表明,稳态液动力采用流场仿真插值法所获得的静态性能仿真结果与试验结果具有很高的吻合度。     

一种新型单向节流阀的设计与研究

提供了一种安装在家用空调的连接管和主毛细管之间的新型单向节流阀,用于控制制冷剂的单向导通。详细介绍了这种新型单向节流阀的结构特征、工作原理以及注意事项。分析了单向节流阀的用途特点,并对单向节流阀的结构进行了初步的设计,以指导用户及专业制冷技术人员正确使用。     

如何解决挖掘机动臂油缸单向节流阀的不同步问题?

动臂油缸是挖掘机工作装置的重要组成部分,用以完成动臂的升降。工作中为了提高工作效率,使动臂快速上升,就要求动臂油缸进油流量要大。但下降时因增加了工作装置的自重,可能会造成因动臂降落速度太快而发生危险,如砸坏工作装置或铲斗撞坏运料车辆等事故,所以在动臂油缸大腔回路上装有可调式单向节流阀。这种单向节流阀既可使动臂油缸大腔进油不受任何阻碍,还可根据动臂下降速度要求通过调整阀的开度来控制大腔的回油速度。WY32和WY20两种液压挖掘机都装有两个动臂油缸和两个可凋式单向节流阀,其原理如图1所示。调节单向节流阀时…     

CA6140车床尾座的改进

CA6140车床在钻孔时,尾座移动频繁,劳动强度大,生产效率低。为此,我们利用液压技术对尾座进行了如图所示的改进。 在图示位置中,二位四通电磁阀4通电时油液径单向行程节流阀10进入液压缸右腔,回油径节流阀3和电磁阀4回油箱9,实现了尾座快进。当挡块把单向行程节流阀10的阀心压下时,油液进入节流阀     

位移-电反馈型插装式比例节流阀主阀流场数值模拟分析

为掌握位移-电反馈型插装式比例节流阀主阀腔内流体流动区域的流场分布情况等基础问题,将CFD技术应用到该阀主阀内部三维流场分析中.应用数值模拟技术进行了三维网格划分,得到了位移-电反馈型插装式比例节流阀在两种不同开口度下流体的压力、流速及流线情况,对流场仿真结果进行了对比分析.研究结果揭示了该阀主阀腔内的流场分布情况,给...     

轴向移动式单向节流阀

在自制的气液联动机构机床中,为了实现慢速工作进给和快速退回的动作要求,往往需要在管路中装置单向节流阀,控制流量的大小,以改变速度的快慢。我厂九车间的师傅们试制成功了一种轴向移动式单向节流阀(见图),经在两台机床上使用,性能较好。单向节流阀的工作是这样的:油液从A向流入,B向流出时,由于压力油的作用,使钢球克服弱弹簧的弹力,压向下方,则油路便打开,油液     

气缸充(排)气回路中的元件尺寸设计

气缸充（排）气回路中的元件尺寸设计徐文灿双作用气缸典型的充（排）气回路如图１所示。充气回路是压缩空气流经电磁换向阀、单向节流阀、各处连接管及管接头,向气缸有杆腔充气。排气回路是气缸无杆腔内的压缩空气经单向节流阀、各处连接管及管接头、电磁换向阀,...     

磁流变液控制阀在电控系统中应用的研究

磁流变液作为一种新型的智能材料，在生产实际中有着广泛的应用前景。该文探讨了通过使用磁流变液控制阀，对传统液压控制系统中的一个部件——单向节流阀进行控制，以达到对整个系统流量变化进行实时控制与调节目的，保证传统液压系统的稳定。     

液压比例阀阀芯V形槽口的CFD解析

带V形槽口的滑阀阀芯在比例阀中应用非常广泛,槽口结构对阀开启过程中的比例特性和作用在阀芯上的液动力影响很大.运用CFD解析方法对带V形槽口的液压滑阀阀腔内的流场进行求解,得到不同开口度对应的流量和液动力.分析解析结果可知:应该用稳态计算求解通过阀口的流量和作用在阀芯上的稳态液动力,用移动网格技术结合瞬态计算求解瞬态液动力.     

Formation of a flange from a flat blank with a hole

A model of axisymmetric formation of a flange from a flat blank with a hole by expanding by a hard punch with a fixed flat flange is given, taking into consideration contact friction, change of wall thickness, strengthening of material, and the tool bending radius. Elastic, elastic-plastic and hard-plastic process stages are studied.     

装载机新型工作装置设计理论的研究

推出了一种装载机工作装置的新型机构 ,克服了传统工作装置由于设计误差而产生的“干涉”现象 ,实现了无铲斗平移引导油缸工作装置 ,使其结构大为简化 ,设计极为简单。此外 ,还分析研究了这种新机构的设计计算方法。为今后进一步改进现有装载机工作装置提供参考     

Estimation of a Bottom Echo-Signal Level Reflected from a Plane Surface of a Cylindrical Article Using a Normal Probe Operating in a Pulsed Mode

The influence of the pulsed operating mode on a bottom echo-signal level reflected from a plane surface of a cylindrical article is studied during variations in the article's radius. It is shown that the pulsed character of a signal smoothens this function significantly as compared to that in the previously computed continuous mode. Numerical estimates of the bottom echo signal have been made for the ultrasonic inspection of wheel-pair axles of railway vehicles.     

某制冷压缩机爆炸事故的分析

广州市某冷库一台冷凝器压缩机在试压检漏时发生整体爆炸.经现场调查和对爆炸碎片、残骸的研究,分析了爆炸的过程,判断事故原因为试压工艺问题和操作不当,并给出了改进措施.     

Buckling of a thin spherical shell inside a spherical cavity of a contracting massive body

The problem of buckling of a thin elastic spherical shell inside a spherical cavity of uniformly contracting massive body is considered. This problem arises, for example, when designing pressure vessels made of composite materials with a thin metal cap layer. It is assumed that at the beginning of the compression the shell fits tightly against the wall of the cavity (to the rigid frame). An algorithm for searching the equilibrium state of the shell in the supercritical state is described. As a result of solving the problem, among other things, critical values of compressive strain and shell configuration in the supercritical state were obtained.     

The use of a segmented cathode of a drift tube for designing a track detector with a high rate capability

Detector rate capability is one of the main parameters for designing a new detector for high energy physics due to the permanent rise of the beam luminosity of modern accelerators. One of the widely used detectors for particle track reconstruction is a straw-detector based on drift tubes. The rate capability of such detectors is limited by the parameters of readout electronics. The traditional method of increasing detector rate capability consists in increasing their granularity (the number of “elementary” detectors = readout channels) by reducing the straw diameter and/or by dividing the straw anode wire into two parts (for decreasing the rate per readout channel). A new method of designing straw detectors with a high rate capability is presented and tested. The method is based on dividing the straw cathode into parts and the independent readout of each part.     

Operation of a tight joint under a torque

A tight joint subjected to a torque is considered, in the case of pliability of the joint components and tangential pliability of the contact layer. On that basis, the torque distribution over the joint length may be determined more precisely, and fretting wear may be predicted.     

Improved running-in of a frictional pair consisting of a cylinder lining and a piston ring

Improvement in the running-in of internal combustion engines by applying copper and antifrictional coatings to the cylinder surface is considered. The recommended optimal conditions correspond to higher surface quality and shorter running-in.