Analysis of Oil Consumption in Cylinder of Diesel Engine for Optimization of Piston Rings

The performance and particulate emission of a diesel engine are affected by the consumption of lubricating oil. Most studies on oil consumption mechanism of the cylinder have been done by using the experimental method, however they are very costly. Therefore, it is very necessary to study oil consumption mechanism of the cylinder and obtain the accurate results by the calculation method. Firstly, four main modes of lubricating oil consumption in cylinder are analyzed and then the oil consumption rate under common working conditions are calculated for the four modes based on an engine. Then, the factors that affect the lubricating oil consumption such as working conditions, the second ring closed gap, the elastic force of the piston rings are also investigated for the four modes. The calculation results show that most of the lubricating oil is consumed by evaporation on the liner surface. Besides, there are three other findings： （1） The oil evaporation from the liner is determined by the working condition of an engine; （2） The increase of the ring closed gap reduces the oil blow through the top ring end gap but increases blow-by; （3） With the increase of the elastic force of the ring, both the left oil film thickness and the oil throw-off at the top ring decrease. The oil scraping of the piston top edge is consequently reduced while the friction loss between the rings and the liner increases. A neural network prediction model of the lubricating oil consumption in cylinder is established based on the BP neural network theory, and then the model is trained and validated. The main piston rings parameters which affect the oil consumption are optimized by using the BP neural network prediction model and the prediction accuracy of this BP neural network is within 8%, which is acceptable for normal engineering applications. The oil consumption is also measured experimentally. The relative errors of the calculated and experimental values are less than 10%, verifying the validity of the simulation results. Applying the established simulation model and the validated BP network model is able to generate numerical results with sufficient accuracy, which significantly reduces experimental work and provides guidance for the optimal design of the piston rings diesel engines.

Syntheses and Tribological Property of CrMoN/MoS2 Multilayer Films on Piston Rings of Heavy Vehicle Engine

In order to prolong the service life of piston rings of heavy vehicle engine and decrease the friction and wear of piston rings and cylinder liner,CrMoN/MoS_2 multilayer films were deposited on the surface of rings by magnetron sputtering and low temperature ion sulfuration.FESEM equipped with EDX was adopted to analyze the compositions and morphologies of surface,cross-section,and wear scars of the multilayer films.The nano-hardness and Young＇s modulus of the films were measured by a nano tester.Tribologicalproperties of the films were tested by an SRV~174;4 wear tester.The experimentalresults indicate that the structures of the multilayer films are dense and compact.The films possess nano hardness value of approximately 26.7 GPa and superior ability of plastic deformation resistance.The multilayer films can activate solid lubricating,and possess an excellent antifriction and wear resistance under the conditions of heavy load,high frequency,high temperature,and dynamic load.

Influence of Internal Combustion Engine Parameters on Gas Leakage through the Piston Rings Area

In this work, the influence of internal combustion engine parameters (cylinder-piston clearance, piston head height, the first segment position, gap of the first piston ring and gap of the second piston ring, piston rings’ axial clearance, intake valve debit coefficient) gas leakage from the combustion chamber through the piston rings’ area was investigated. This influence was studied by making an initial forming operation over gas leakage in the analyzed area.

Thermal Stress Monitoring on Piston Rings by Real Time Holographic Interferometry

In this paper, real time holographic Interferometry (RTHI) technique was used to monitor the thermal stress on the piston rings. The piston rings holograms were recorded and the holographic plate replaced on the holder after development. The piston ring was subjected to thermal stress as it was illuminated by Laser beam acting as the object beam. This process led to generation of interferograms which were captured by a CCD camera at different temperatures. The captured interferograms were analyzed using atmosfringe version 3.3 software. From the analysis, the peak to valley (P-V) aberrations measured for each of the piston ring varied for the same temperature value. The P-V aberrations ranging from 0.0128λ to 1.2989λ were obtained. From this result, it was evident that the three rings on the piston had different unique structural characteristics due to their function.

Laser texturing of piston ring for tribological performance improvement

The radial surface coating layer of compression piston rings is used to improve their wear resistance during the internal combustion engine operation.However,at top dead centers,the friction coefficient of the piston ring–cylinder liner pair is detrimental to the engine’s tribological performance.In this work,dimples with different texture dimensions and densities were tested in a home-developed tribometer.The friction coefficient was measured for all samples,and for those with the best results,their wear resistance was assessed.The texture with an aspect ratio of 0.25 and a density area of 15%reported the best tribological results.

Effects of Nano-Particles on the Tribological and Thermal Properties of Piston Ring-Cylinder Liner

The effects of ultra-dispersed diamond (UDD) on the friction force, wear, and temperature of tri-bological pairs have been investigated. The experimental tests were carried out on a modified piston ring-cylinder liner bench tester with different particle mass fractions of 0, 0.02%, and 0.10%. The results show that compared with a pure fluid, the mixture of the fluid and UDD not only reduces the friction and wear, but also reduces the bulk temperature of the specimen. The mechanism by which the UDD lubricant improves the tribological properties has some relationship with surface topography, because it can increase the bearing capability of surfaces.

Design approach for optimization of a piston ring profile considering mixed lubrication

To reduce the friction of a piston ring while maintaining a large oil film load-carrying capacity,an approach comprising of the inverse method and the sequential quadratic programming algorithm was proposed.The approach considers the variation of mixed lubrication and variable lubricant viscosity with temperature along the engine stroke,is developed to optimize the profile of a piston ring.A piston ring profile is represented by a polynomial function.A case study of the second piston ring shows that the proposed method can be applied for the optimization of a piston ring profile.In addition,this paper illustrates the effects of the degree of a polynomial function.The results show that the minimization of friction and maximization of oil film load-carrying capacity can be balanced simultaneously when the degree of the polynomial is 2 and 5.

Effect of carbon nanotubes on friction and wear of a piston ring and cylinder liner system under dry and lubricated conditions

This study involves the application of carbon nanotubes (CNTs) to a piston ring and cylinder liner system in order to investigate their effect on friction and wear under dry and lubricated conditions.Carbon nanotubes were used as a solid lubricant and lubricant additive in dry and lubricated conditions,respectively.Simulation and measurement of friction and wear were conducted using a reciprocating tribometer.Surface analysis was performed using a scanning electron microscope and an energy dispersive spectrometer.The results indicate that carbon nanotubes can considerably improve the tribological performance of a piston ring and cylinder liner system under dry sliding conditions,whereas improvement under lubricated conditions is not obvious.Under dry friction,the effective time of the CNTs is limited and the friction coefficient decreases with an increase in CNT content.Furthermore,the dominant wear mechanism during dry friction is adhesive.

Piston-ring and Cylinder-liner Lubrication in Internal Combustion Engines Based on Thermo-hydrodynamic

Currently the extruded effect,roughness to the lubricant shear thinning,temperature changes and other factors or some combination of a single factor mainly considered in the lubrication study of piston ring-cylinder.In the study of the energy equation,the oil viscosity-temperature properties,adsorption layer characteristics are usually not considered.So the theoretical research is different from the actual situation of engineering.The lubrication of piston ring-cylinder liner system in internal combustion(IC) engines is studied here based on the theory of thermal flow.An unsteady and compressible hydrodynamic lubrication model with an equivalent viscosity based on shear and extruded flow factor is derived by employing the viscosity-temperature relationship,meanwhile,characteristics such as lubricating oil’s density varying with pressure and temperature,thickness of adsorbent layer and oil film’s geometry are also considered in this model.While setting up the energy equation,the effect of lubricating oil’s volume expansion and viscous dissipation on temperature,the heat conduction along oil film’s thickness direction are considered.Finite difference equation is formed by using a first-order difference scheme in time scale and second-order difference scheme in space scale.A common diesel engine is introduced as an instance to predict the distribution of the minimum oil film thickness in the piston ring-cylinder liner system.The results of simulation calculation show that the minimum oil film thickness will decrease especially around the top dead center when the oil’s volume expansion,viscous dissipation and heat conduction are considered,which implies that:it is essential to take the thermal flow idea into account during investigating piston ring-cylinder liner system’s lubrication.A more complete piston ring-cylinder liner lubrication theory was established according to thermal fluids from the perspective of research.It is more helpful to guide the practical application of engineering to improve the accuracy of forecasting the minimum film thickness.On the other hand,distribution of the minimum oil film thickness shows a nonlinear property if the thickness of piston rings and cylinder liner adsorbent layer are involved in the analysis.It may be feasible to increase the minimum oil film thickness by varying surface roughness and material properties of piston rings and cylinder liner.

Tribological performance and scuffing behaviors of several automobile piston rings mating with chrome-plated cylinder liner

The friction and wear properties,as well as the scuffing resistance,of different piston-ring coatings mating with a chrome-plated cylinder liner were investigated.Interrupted wear tests under the lubricant starvation condition were conducted to examine the wear behavior of Cr-diamond coating(GDC)and diamond-like coating(DLC).The results indicated that the DLC coating had outstanding tribological properties(small coefficient of friction and wear loss)at 150°C,while the GDC coating exhibited better performance at an elevated temperature(240°C).The DLC coating had a better scuffing resistance;no material adhesion occurred for 70 min under the unlubricated condition.The interrupted wear behaviors revealed that the scuffing process of the GDC coating involved the consumption of lubricant oil with relatively stable wear,a reduction in the friction force,and the occurrence of scuffing,in sequence.In contrast,although the friction force also increased after a short period of weak friction,no scuffing was observed.This is attributed to the formation of a mixed oxide and graphitic C tribolayer.

Blow-by and tribological performance of piston ring pack during cold start and warm idle operations

To reduce the fuel consumption of internal combustion engines, more attention has been paid to the tribological performance of the piston ring pack during the cold start and idle operations. In this research, a numerical model considering the cylinder liner deformation and the piston ring conformability is developed to predict the blow-by, lubrication, friction and wear of the piston ring pack under different operating conditions. The gas flow rate, inter-ring gas pressures, minimum oil film thickness, frictional force and wear load during cold start are calculated and compared with those during warm idle operating conditions. The results show that cylinder liner deformation and piston ring conformability together obviously affect blow-by and other tribological performance. Meanwhile, it is found that friction loss is larger during cold start than during warm idle operating conditions. However, the wear process is more severe during warm idle operation than during cold start. From this research, the blow-by and tribological performance of the piston ring pack during cold start and warm idle operations are understood more deeply.

Current Situation of Piston & Piston Ring Industry in China

Ⅰ. Current Situation At present, there are more than 100 piston and/or piston ring manufacturers all over China, and the figure is continuously rising. Among them, some manufacturers are specialized or mainly engaged in the production of pistons, e. g. Shanghai Piston Plant, Shandong Piston Plant, etc.; some manufacturers are specialized or

Competitive surface interactions of critical additives interacted with piston ring/cylinder liner components under lubricated running-in conditions

The running-in frictional experiments were conducted under simulated engine conditionswith actual piston rings and iron cylinder liner combinations. Elemental analyses of the wear tracksindicate that antiwear agent ZDTP is quite different from the Mg- and Ca-containing detergents inthe selectivity towards the tribosurfaces of both rings and liners. It is suggested that the tribo-chemical activity of tribosurfaces plays the role in governing the characteristic population of func-tional additive elements.

The behaviour of inlet roughness in lubrication of piston ring-cylinder liner

The improvement of lubrication of piston ring-cyinder liner is always in demand, andsurface roughness behaviour plays a very important role. The present paper will explore this be-haviour and investigate how the inlet roughness of ring influences the lubrication of pistonring-cylinder. The quantitative results of this combination of surface roughness on friction force, oilfilm thickness and frictional power loss are given and discussed.

Numerical simulation of piston ring in the mixed lubrication

Piston and piston ring lubrication is a factor that strongly affects the performance of thereciprocating internal combustion engine. When the oil film thickness becomes smaller than a cer-tain value, depending upon the roughness of the surfaces in contact, mixed lubrication has to beconsidered. This paper analyzes the lubrication of piston ring and predicts pressure distribution,lubricant film thickness and surface deformation. The work is based on a unified numerical ap-proach assuming that the pressure distribution obeys Reynolds equation in hydrodynamic lubrica-tion regions while in asperities contact regions, the contact pressure can be obtained through theso-called reduced Reynolds equation. The computation experience shows the unified equationsystem is stable and can deal with severe operating conditions.

基于改进EEMD-MB1DCNN的船用柴油机缸套-活塞环故障诊断

针对船用中高速柴油机缸套-活塞环振动信号非线性非平稳性以及同类型不同损伤程度故障发生时振动信号时频域特征相似、故障难以识别等问题,利用振动信号辨识故障,提出一种基于改进集成经验模态分解方法和多模块一维卷积神经网络端到端缸套-活塞环故障诊断方法,通过设计固有模态分量IMF信息质量筛选准则对EEMD分解出的IMFs进行重新排序,获得包含更多凸显故障特征成分的重构信号,输入到上述神经网络模型,通过振动信号分析并与现有方法比较,评估所设计IMF信息质量筛选准则与所搭建模型的性能,试验结果显示该方法能准确、有效地识别缸套-活塞环故障类型。在判断该易损件同类型不同磨损程度故障诊断中有较高的准确率,能对故障状况进行有效的特征提取与故障分类。

内燃机活塞环材料及表面处理技术研究现状与发展趋势

活塞环是内燃机中重要的零部件之一,该部件的摩擦损耗占内燃机总摩擦损失的26%。因此,活塞环材料的选用及其表面处理研究对于优化提升内燃机性能、延长服役寿命具有重要意义。简单介绍并总结了内燃机活塞环常用材料及其发展趋势,详细综述了激光表面织构技术、表面涂层技术以及表面复合技术在内燃机活塞环减摩抗磨方面的研究和应用现状。其中,激光表面织构技术(LST)可起到接纳磨屑、保持油膜等作用,从而降低活塞环表面摩擦和磨损,但由于织构形貌和几何参数特征对摩擦学性能的影响较为复杂,仍需结合实际工况进一步研究并优化。以镀铬、热喷涂、气相沉积及激光熔覆为代表的涂层技术也常用于活塞环的表面强化处理,但涂层材料种类繁多,难以形成统一的行业标准进而规模应用。此外,通过合理复合多种表面处理技术,比如微弧氧化与电泳沉积复合、超声滚压与离子渗氮技术复合、磁控溅射和低温离子渗硫复合等,可实现优势互补、发挥协同作用,有效改善接触表面的摩擦性能,为活塞环的减摩增寿研究开拓了新的思路。最后对未来活塞环材料开发应用及其减摩抗磨方面的研究发展进行了展望。

低硫条件下船舶主机缸套-活塞环磨损现状与应对策略

国际海事组织(IMO)的“限硫令”于2020年1月在全球范围内实施后,燃用低硫燃油(LSFO)成为许多远洋公司的主要选择。对多家远洋公司船舶主机燃用LSFO后的运行状况进行调研,发现缸套、活塞环等零部件存在异常磨损及故障显著增多的现象。将LSFO对船舶主机的影响以及其实际应用案例进行分析与总结,并针对燃用LSFO的主机所出现的异常磨损和故障现象提出应对策略。该研究有助于解决LSFO条件下船舶主机缸套和活塞环异常磨损问题的实际需求,希望进一步推动LSFO条件下缸套和活塞环异常磨损的机理研究。

合金灰口铸铁气缸套组织形貌与耐磨性研究

针对5种成分和组织的灰口铸铁气缸套,包括2种贝氏体铸铁气缸套和3种珠光体铸铁气缸套,全面分析了其成分、相组成及硬度等材料特性,将喷钼活塞环与5种合金灰口铸铁气缸套对磨,通过比较各配对副的摩擦磨损性能,获得了喷钼活塞环与5种合金灰口铸铁气缸套的匹配规律。研究结果表明:5种气缸套材料均为由硬质相、基体和石墨构成的复合耐磨结构,各组分的性能、分布及其配比,是决定耐磨性的关键因素。珠光体基体气缸套的磨损量相对稳定,气缸套与活塞环的相对磨损量正常;铸态贝氏体气缸套磨损较轻,配对活塞环的磨损量比珠光体气缸套大;贝氏体气缸套和活塞环的磨损均量很小。

基于激光熔覆的缸套表面梯度材料制备及其摩擦学性能研究

目的研究功能梯度材料对缸套表面的抗磨减摩作用,提升缸套-活塞环配副的摩擦学性能。方法通过激光打标机在缸套表面制备具有30°角规则纹理排布的凹槽,在凹槽内采用同轴送粉的方式熔覆镍含量不同的铁基粉末,分析熔覆合金层的金相组织,并利用往复式摩擦磨损试验机研究在一定载荷压力下功能梯度材料缸套的摩擦学性能。结果熔覆层金相组织呈现梯度排布,熔覆层与基体材料分子原子交互扩散形成良好的冶金结合。牌号为350、镍质量分数为4.2%、铁质量分数80%的粉末所制备的功能梯度材料,减摩效果最为明显,相比未经处理的对照组,平均摩擦因数降幅为25.4%,且该组在试验中接触电阻的平均值最大,相比对照组提升了63.45%。牌号为330、镍质量分数为9%、铁质量分数为70%的粉末制备的缸套,表面支撑指数最高为0.78,相比于未处理的对照组,增幅达到35%,且试验组活塞环经摩擦后,磨损量均小于对照组。结论制备了30°角分布的功能梯度材料,能使得缸套-活塞环摩擦学系统在工作过程中摩擦副的润滑油膜厚度更厚,且在运行过程中更稳定,以减少摩擦力和降低摩擦因数。同时,增强其支撑能力和储存润滑油的能力,使所制备的缸套摩擦因数显著降低。牌号为350的材料,改善摩擦学性能的效果最优。