A New Clearance Design Method for Reciprocating Fuel Pumps of Medium-Speed Diesel Engines

A new clearance design method is proposed for a reciprocating fuel pump. Structural and hydrodynamic lubrication analyses were conducted to design the clearance of the pump, and the former was used to evaluate the clearance reduction due to the deformation that results from applying maximum supply pressure. The reduction in the maximum clearance was used as the limit of the design, and the two-dimensional Reynolds equation is used to evaluate the lubrication characteristics of the pump with variations in the viscosity and clearance. The optimal clearance in the pump must be separately designed in both the stem and the head because the lubrication characteristics and the deformation patterns of the two parts are different. The validity of the numerical model was then verified by determining that the position of the wear was also similar to that of the minimum film thickness. Moreover, a rig test system was also used to verify the clearance of the proposed design method.     

轴向柱塞泵回程盘与滑靴间接触情况及碰撞干涉分析

轴向柱塞泵运行过程中回程盘与滑靴会产生碰撞干涉甚至出现回程盘崩裂和滑靴拉脱的现象。首先,通过对回程盘与滑靴的运动学特性和接触动能损失进行分析,得出影响碰撞干涉程度的因素;然后,通过ADAMS仿真分析,得出回程盘钻孔与滑靴颈部的接触规律和不同影响因素下碰撞干涉程度的变化规律;最后对奇偶柱塞数的柱塞泵进行仿真分析,得出回程盘钻孔与滑靴颈部接触时较为严重的碰撞干涉程度出现的原因,为回程盘结构优化提供参考依据。     

活塞顶面热障涂层对活塞热负荷的影响

活塞顶面热障涂层可以有效降低活塞工作热负荷、提高活塞使用寿命。以一款非道路高压共轨柴油机铝合金活塞为研究对象,采用硬度塞测温法试验测试了无热障涂层活塞在最大转矩工况下表面19个特征点的温度值,同时采用等参法建立了活塞有限元仿真分析模型,对比分析了活塞顶面热障涂层对活塞温度场和热应力场的影响。研究结果表明：活塞顶面热障涂层能有效降低活塞头部和环槽区域的工作温度,活塞头部顶面区域温度下降幅度为20~32 ℃,一环和二环的环槽区域温度下降幅度为15~18 ℃;但活塞顶面采用热障涂层后,活塞基体顶面黏结层区域的热应力会急剧升高,活塞基体顶面、喉口区域以及边缘棱角处热应力集中现象明显,在活塞顶面喉口黏结层区域最大热应力达到291MPa,易导致热障涂层的剥落失效。     

带导向管的子母弹活塞式抛撒弹道建模及数值仿真

在子母弹活塞式抛撒背景下，提出了带导向管的抛撒机构，分析单燃烧室和双燃烧室结构工作原理，对子母弹系统抛撒散布过程的计算方法进行探讨,建立抛撒过程内弹道方程组及子弹散布模型，并在此基础上进行了数值仿真。系统总结了子母弹活塞式抛撒特点及性质；将带有导向管的活塞式抛撒技术和母弹旋转融合在一起，增强了子弹空中散布效能；子弹弹道模型及仿真给出了子弹空中运动规律及散布规律。为抛撒过程的研究、抛撒机构的工程化设计和结构优化、空中抛撒散布效果分析提供理论参考。     

考虑结构动态变形的缸套-活塞环润滑建模分析

缸套在燃烧冲击和活塞敲击激励下会产生接近表面粗糙度的动态变形,极有可能影响缸套-活塞环组件间的摩擦润滑过程。为了研究缸套动态变形潜在的影响,将动力学仿真获取的缸套内表面的动态变形经过处理后导入到润滑模型中,同时采用数值积分计算的方式对油液压力应力因子和剪切应力因子进行实时计算求解,使仿真计算更加符合实际情况。通过搭建同时考虑缸套变形与油液剪切特性影响的改进润滑模型,计算得到整个工作循环内活塞环上的最小油膜厚度和摩擦力曲线。结果表明:考虑缸套动态变形后的最小油膜厚度和摩擦力曲线出现了明显的波动,而且考虑缸套动态变形后的摩擦力比未考虑之前出现了明显下降。     

热障型内燃机活塞设计

主要针对目前内燃机的大功率、小排放、低噪声的要求，根据隔热发动机的热障机理，介绍了几种热障型活塞的设计方案。     

对往复式压缩机故障的危害探究

往复式压缩机作为工业生产的重要设备有着无可替代的价值。是生产生活必不可少的重要器械。作为最常见的一种压缩机,其故障的危害性不容忽视。本文正是从此出发,分析讨论往复式压缩机重要部件与循环系统的故障对压缩机的影响。     

无油润滑压缩机设计中的pv值及其应用研究

对无油润滑压缩机设计中的Pv值进行了研究。对活塞环的磨损特性分析表明，pv值越大，活塞环磨损越大、寿命越低。通过pv值的计算推得由pv值和[pu]值来确定活塞环数的计算式。经分析认为一般资料所给活塞环材料的[pv]值过低，所得环数过多，给压缩机在结构尺寸、成本、加工和装配等方面带来问题。推荐了常用无油润滑材料的[pv]值。实际应用表明按推荐值设计的压缩机结构紧凑，活塞环运行寿命达4000h以上。     

Hydraulic lift systems with piston type pump

More difficult conditions of oil production process in recent years impose the necessity of finding out new technical solutions that will provide reliable and efficient lifting of reservoir fluid to the surface.Technical solution presented in this paper, hydraulically driven piston pump, is one of the attempts in the field of artificial exploitation methods, to find a solution that will work effectively in different well types (vertical, horizontal and directional) and at depths that are greater than those achieved until today.The task of this paper is to show the innovation in the pump construction. Innovations are made in the coiled tubing construction, one pipeline instead two or three; double acting type pump with reservoir fluid repression, towards the surface, through a channel drilled in the piston.The new technical solution, laboratory prototype, has been tested and the results are presented in tables and on graphs in this paper. The aim is that after testing the laboratory prototype comes to the data that will be used for the design of industrial product.     

某轻型车辆液力减震器活塞杆断裂失效分析

对发生断裂失效的某型轻型车辆液力减震器活塞杆进行断口失效分析。为查找失效原因对活塞杆根部的加工状态进行分析,同时对活塞杆根部有无过渡圆角的两种情况进行有限元应力分析。结果表明,活塞杆的断裂属于高周疲劳断裂,引起早期疲劳断裂失效的主要原因是因为活塞杆根部过渡截面未加工过渡圆角所造成的。与未加工过渡圆角时相比,加工有R5的过渡圆时可以使活塞杆根部的最大轴向应力下降36%。