涨圈高速旋转密封失效及涨圈的表面处理

分析了涨圈高速旋转密封的主要失效形式及影响因素,在标准实验机和发动机模拟实验台架上对涨圈表面刷镀锢铟铜合金和热喷涂PTFE的减摩耐磨性能同磷化处理进行了比较.结果表明刷镀铟铜合金能够改善涨圈摩擦副的摩擦状态而热喷涂PTFE使摩擦状态恶化.     

弹簧垫圈的涨圈分析与新型弹簧垫圈设计

对涨圈失效的弹簧垫圈进行化学成分、金相组织、硬度试验、韧性试验和力学分析。对拧紧过程中的垫圈的上下两表面的摩擦力及其合力的分析,找出斜口这一弹簧垫圈结构上的缺陷是导致弹簧垫圈出现涨圈的原因,为杜绝弹簧垫圈的涨圈失效改进了它的设计。     

涨圈的加工工艺研究

分析了涨圈的结构,确定了涨圈加工的工艺方案,并设计制作了用于外磨和内磨的专用胎具,保证了所加工涨圈的质量满足要求。     

特殊涨圈弹簧的设计研究

分析了一种特殊涨圈弹簧在工作时的受力状态,通过对这种涨圈弹簧的径向负荷的计算、刚度的计算以及应力分析等,提出了这种特殊涨圈弹簧的设计方法,从而使该种涨圈弹簧更加合理、有效地发挥作用。最后,例举了该涨圈弹簧设计实例,给出了其常用的材料和设计参考数据,通过对实件的测试,验证了该设计方法的可行性。     

轮毂轴承密封失效分析

介绍轮毂轴承密封结构与主要结构参数,以第3代轮毂轴承单元密封结构为例,讨论了密封失效诊断、磨痕分析、残余过盈量获取与磨耗重构方法,并总结了密封失效的8类原因,为轮毂轴承的密封设计与失效分析提供了参考。     

机械密封的失效分析

列举机械密封失效的外部现象,分析产生这些现象的原因并提出补救措施,对维修与排除机械密封故障有一定的帮助.     

螺旋密封气吞及密封失效机理分析

本从泵的角度对螺旋密封“气吞”及“密封失效”现象作出了合理,全面的解释,并提出一种新型组合螺旋密封,分析结果表明,转速较高时,迷宫螺旋密封优于组合螺旋密封,优于单一结构螺旋密封,具有一定的工程使用价值。     

干气密封的选用及失效分析

介绍干气密封的结构及工作原理;基于干气密封的结构类型及使用条件,给出干气密封的选用原则;分析干气密封失效的原因并给出相应的防范措施。干气密封要根据被输送介质的特性、介质的温度和压力范围、干气密封使用环境及密封系统转速等选用。导致干气密封失效主要原因有设计不合理、密封气源质量差、控制系统的故障等,在设计和使用时必须加以注意。     

Investigation into the effect of piston ring seals on an integrated squeeze film damper model

This research presents an advanced squeeze film damper model that integrates piston ring seal geometry, fluid inertia, and film cavitation to study their combined features. The configuration of the piston ring seal is inspected, and different sealing scenarios are discussed. The flow rate in the seal arrangement is determined on the basis of the pressure gradient according to thin film theory. Moreover, the governing equation for the flow in the film land that considers fluid inertia is solved using the linear complementarity problem method to address the cavitation phenomenon. Validation is performed by comparing the model prediction with long bearing and short bearing models under different seal dimensions. Results show that an oversized gap in the seal grooves and a large frictional coefficient may lock the piston ring seal in the seal groove and thus reduce seal efficiency.

     

Scuffing failure analysis and experimental simulation of piston ring–cylinder liner

The scuffing failure phenomenon of piston ring–cylinder liner is studied theoretically and experimentally. The load and bulk temperature when scuffing failure occurs are measured under different engine speed, lubricant, and environmental temperature in a bench test. Based on the experimental results, the asperity capacity when scuffing occurs is evaluated. Surface contact temperature is determined with the measured bulk temperature and the surface flash temperature calculated by Blok theory. The scuffing failure threshold of piston ring–cylinder liner is established by using specific oil film thickness. This revised version was published online in June 2006 with corrections to the Cover Date.     

提高无油润滑往复活塞压缩机活塞环支承环使用寿命的方法

分析了影响活塞环、支承环使用寿命的主要原因,及采取一些相应的措施和方法,以改善和提高活塞环、支承环的使用寿命。     

活塞环工艺技术综述

活塞环性能的优劣直接影响到内燃机的整体性能,随着现代内燃机的发展,对于活塞环提出了越来越高的要求。要实现活塞环的特性,加工技术就尤为重要,本文阐述了现代活塞环生产技术特点,并与传统加工方法进行对比,对它们的优缺点进行了分析,并体现了现代活塞环技术的发展趋势。     

Numerical simulation of piston ring lubrication

This paper describes a numerical method that can be used to model the lubrication of piston rings. Classical lubrication theory is based on the Reynolds equation which is applicable to confined geometries and open geometries where the flooding conditions are known. Lubrication of piston rings, however, fall outside this category of problems since the piston rings might suffer from starved running conditions. This means that the computational domain where the Reynolds equation is applicable (including a cavitation criteria) is unknown. In order to overcome this problem the computational domain is extended to include also the oil film outside the piston rings.The numerical model consists of a 2D free surface code that solves the time dependent compressible Navier–Stokes equations. The equations are cast in Lagrangian form and discretized by a meshfree moving least squares method using the primitive variables u, v, ρ for the velocity components and density, respectively. Time integration is performed by a third order Runge–Kutta method. The set of equations is closed by the Dowson–Higginson equation for the relation between density and pressure. Boundary conditions are the non-slip condition on solids and the equilibrium of stresses on the free surface. It is assumed that the surrounding gas phase has zero viscosity. Surface tension can be included in the model if necessary. The contact point where the three phases solid, liquid, and gas intersect is updated based on the velocity of the solid and the angle between the normals of the solid and the free surface.The numerical model is compared with the results from an analytical solution of the Reynolds equation for a fixed incline slider bearing. Then results from a more complicated simulation of piston ring lubrication are given and discussed.     

Lubrication characteristics of dual piston ring in bent-axis type piston pumps

The bent-axis type of piston pump driven by the piston rod works by the piston rod driving the cylinder block; because of this the taper angle of the piston rod and the swivel angle between the cylinder block and the shaft are important design factors. If these factors cannot satisfy the conditions for optimum design, the friction loss between the cylinder bore and the piston increases, and the pump can fail to work under conditions of severe friction and wear. Since the piston reciprocates in the cylinder bore with high velocity, at the same time rotating on its own axis and revolving on the center of the cylinder block, a decrease of the volume efficiency is generated because of the leakage between the cylinder bore and the piston. Therefore, to prevent this, the piston ring is designed to be at the end of the piston, and the friction characteristics between the piston ring and the cylinder bore require further research due to their great influence on the performance of the piston pump. Thus, in this paper, the elastohydrodynamic lubrication (EHL) analysis of the film thickness, the pressure distribution, and the friction force, have been studied between the piston ring and the cylinder bore in the bent-axis type of piston pump. The analyzed results show that the friction force is influenced by the rotating speed and the discharge pressure.     

The effect of a non-Newtonian lubricant on piston ring lubrication

The effect of a non-Newtonian oil (shear thinning) on the lubrication of a piston ring is theoretically investigated. A variation of shear strain rate with shear stress that is cubic in form is used to obtain a modified form of the Reynolds equation (dynamic) applicable to a run-in ring profile which is considered to be a double parabola with a central straight portion. Numerical solutions are obtained for the film thickness, pressure and frictional force over a complete stroke for the case of a constant load. Results presented in non-dimensional form show that the effect of pseudo plasticity is to reduce slightly the minimum film thickness, peak pressure ratio and friction coefficient.     

The surface failure and wear of graphite seals

Exfoliated graphite rings are now the most common form of die-formed seal for valve stems, and other stuffing box applications. However, there is very little fundamental knowledge of what determines their friction and wear. In earlier papers, it was shown that the mechanical properties of this material could be represented approximately by a geotechnical model designed for soils or rocks. In this paper, a simple test is described for measuring the friction and wear of seals against steel sliders in a controlled atmosphere. The results, which are rather surprising, can be explained by applying the geotechnical model referred to above, to the case of sliding.     

车削活塞环工装的改进

通过对活塞环车削工装的改进,提高了生产效率,减少了废品和生产成本。