Lubrication adaptability to the variations of combustion modes by texturing cylinder liner in engines

2017 ◽  
Vol 232 (7) ◽  
pp. 946-957 ◽  
Author(s):  
Bifeng Yin ◽  
Bo Xu ◽  
Yanqiang Qian ◽  
Jinghu Ji ◽  
Yonghong Fu
Keyword(s):  
Tribological Properties ◽  
Friction Pair ◽  
Cylinder Liner ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Frictional Loss ◽  
Compression Stroke ◽  
Combustion Modes ◽  
Lubrication Performance ◽  
Micro Dimples

The application of different combustion modes in engines has placed greater demands on the lubrication of cylinder liners and piston rings. In this study, a mixed lubrication model was built to investigate the tribological properties of a liner textured with micro-dimples. The simulation results indicate that surface texturing can improve the lubrication and friction properties of the ring/liner pair and adapt to different combustion modes in an engine. Due to the significant differences in external loads around top dead center of the compression stroke under pre-mixed charge combustion ignition, conventional combustion and retarded injection modes, when the liner remains untextured, the lubrication performance of the friction pair appears to be unstable in a mixed lubrication region. For the textured liner, micro-dimples enhance the hydrodynamic effects between the ring and liner, increasing the oil film thickness and its bearing capacity. As a result, the mixed lubrication interval shrinks and the micro asperity contact is reduced, thus improving the tribological properties of the friction pair. The numerical fluctuation ranges of parameters, the maximum asperity pressure, the average friction force and the frictional loss, are narrowed by 21.6%, 27.8% and 24.5%, respectively, under the three different combustion modes around top dead center of the compression stroke.

Mutual influence of plateau roughness and groove texture of honed surface on frictional performance of piston ring–liner system

2016 ◽  
Vol 231 (7) ◽  
pp. 838-859 ◽  
Author(s):  
Yang Hu ◽  
Xianghui Meng ◽  
Youbai Xie ◽  
Jiazheng Fan
Keyword(s):  
Piston Ring ◽  
Cylinder Liner ◽  
Texture Features ◽  
Groove Depth ◽  
Mixed Lubrication ◽  
Operating Conditions ◽  
Friction Reduction ◽  
Lubrication Performance ◽  
Liner System ◽  
Frictional Performance

The cylinder liner surface finish, which is commonly produced using the honing technique, is an essential factor of engine performance. The characteristics of the texture features, including the cross-hatch angle, the plateau roughness and the groove depth, significantly affect the performance of the ring pack–cylinder liner system. However, due to the influence of the honed texture features, the surface roughness of the liner is not subject to Gaussian distribution. To simulate the mixed lubrication performance of the ring–liner system with non-Gaussian roughness, the combination of a two-scale homogenization technique and a deterministic asperities contact method is adopted. In this study, a one-dimensional homogenized mixed lubrication model is established to study the influence of groove parameters on the load-carrying capacity and the frictional performance of the piston ring–liner system. The ring profile, plateau roughness, and operating conditions are taken into consideration. The main findings are that for nonflat ring, shallow and wide groove textures are beneficial for friction reduction, and there exists an optimum groove density that makes the friction minimum; for flat ring, wide and sparse grooves help improving the tribological performance, and there exists an optimum groove depth that makes the friction minimum.

Piston Ring-Cylinder Bore Friction Modeling in Mixed Lubrication Regime: Part I—Analytical Results

1999 ◽  
Vol 123 (1) ◽  
pp. 211-218 ◽  
Author(s):  
Ozgen Akalin ◽  
Golam M. Newaz
Keyword(s):  
Boundary Conditions ◽  
Friction Force ◽  
Piston Ring ◽  
Cylinder Liner ◽  
Surface Flow ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Friction Modeling ◽  
Crank Angle ◽  
Cylinder Bore

An axi-symmetric, hydrodynamic, mixed lubrication model has been developed using the averaged Reynolds equation and asperity contact approach in order to simulate frictional performance of piston ring and cylinder liner contact. The friction force between piston ring and cylinder bore is predicted considering rupture location, surface flow factors, surface roughness and metal-to-metal contact loading. A fully flooded inlet boundary condition and Reynolds boundary conditions for cavitation outlet zone are assumed. Reynolds boundary conditions have been modified for non-cavitation zones. The pressure distribution along the ring thickness and the lubricant film thickness are determined for each crank angle degree. Predicted friction force is presented for the first compression ring of a typical diesel engine as a function of crank angle position.

Research on Mixed Lubrication Problems of the Non-Gaussian Rough Textured Surface With the Influence of Stochastic Roughness in Consideration

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Chunxing Gu ◽  
Xianghui Meng ◽  
Shuwen Wang ◽  
Xiaohong Ding
Keyword(s):  
Tribological Properties ◽  
Friction And Wear ◽  
Mixed Lubrication ◽  
Textured Surface ◽  
Asperity Contact ◽  
Textured Surfaces ◽  
Negative Skewness ◽  
Non Gaussian ◽  
Stribeck Curves ◽  
Average Flow Model

Abstract In order to find the effects of surface topography on the tribological properties of the rough textured surfaces, an improved mixed lubrication model allowing specifying the standard deviation, the skewness, and the kurtosis was developed. In this model, by considering the non-Gaussian properties of rough surfaces, an improved average flow model was combined with a modified statistical elastoplastic asperity contact model. The performances of the slider bearings with two arrays of anisotropic textures were studied in terms of Stribeck curves. It appears that the tribological properties of the anisotropic textures are sensitive to the sliding direction. Meanwhile, the surfaces with more negative skewness or the lower kurtosis can obtain better tribological performances related to friction and wear.

Optimal design of micro-dimples on crankpin bearing surface for improving engine’s lubrication and friction

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Renqiang Jiao ◽  
Vanliem Nguyen ◽  
Vanquynh Le ◽  
Vancuong Bui
Keyword(s):  
Optimal Design ◽  
Slip Surface ◽  
Asperity Contact ◽  
Bearing Surface ◽  
Content Type ◽  
Multi Objective Genetic Algorithm ◽  
Lubrication Performance ◽  
Study Results ◽  
Micro Dimples ◽  
The Impact

Purpose The purpose of this paper is to investigate the optimal design of micro-dimples on the bearing surface of the crankpin bearing (CB) to ameliorate the engine’s lubrication and friction (ELF). Design/methodology/approach A hydrodynamic model of the CB considering the influence of the asperity contact is built under the impact of the dynamic loading of the slider-crank-mechanism. The micro-dimples on non-slip surface of the bearing are designed and optimized based on the lubrication model and multi-objective genetic algorithm. The performance of optimal micro-dimples on ameliorating the ELF is analyzed and compared with that of optimal CB dimensions via the reduction of the solid contact force, friction force and friction coefficient between the crankpin and bearing surfaces; and the increase of the oil film pressure. Findings The optimal design of micro-dimples on the bearing surface may not only greatly ameliorate the ELF but also make the rotation of the crankpin inside the bearing more stable in comparison with the optimization of CB dimensions. Originality/value This study results not only clearly ameliorates the ELF but also can be applied to the slip/non-slip surface pairs of other journal bearings to enhance their lubrication performance.

Numerical Research on Tribological Performance of Textured Liner Surface Under Different Combustion Modes

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Bifeng Yin ◽  
Shao Sun ◽  
Bowen Wang ◽  
Yanqiang Qian
Keyword(s):  
Piston Ring ◽  
Surface Texturing ◽  
Deep Understanding ◽  
Cylinder Liner ◽  
Tribological Performance ◽  
Mixed Lubrication ◽  
Combustion Mode ◽  
Ic Engine ◽  
Combustion Modes ◽  
Numerical Research

With the increasingly stringent requirements on energy saving and environmental-friendly for internal combustion (IC) engine, new concepts like novel combustion mode and surface texturing technology have emerged. In order to have deep understanding about the application effects of surface texturing into IC engine with new combustion mode, a mixed lubrication calculation model considering surface textures on cylinder liner together with different combustion modes has been built in the present work based on a four-cylinder diesel engine. The numerical research was conducted on the change of the surface tribological performance of textured cylinder liner under different combustion modes. The simulation results indicate that compared with the conventional combustion (CC) mode, the combustion phase of premixed charge combustion ignition (PCCI) mode and retarded injection (RI) mode varies and their in-cylinder peak pressure is different at the beginning of power stroke due to different injection strategies applied, which lead to significant differences between piston ring radial working loads. Near TDC, the mixed lubrication duration of PCCI and RI mode increases slightly in comparison to that of CC mode, and these three boundary lubrication durations are almost same. However, the thickness of lubricant film between friction pair of three modes is quite different, resulting in their different tribological properties. Among these parameters, the dimensionless total friction force (DTFF) and the dimensionless friction work of PCCI mode increase by 82.37% and 18.41% at most, respectively, while those of RI mode decrease by 36.50% and 12.45% at most, respectively, compared with the same parameters of CC mode. Therefore, the variations in tribological property of the textured cylinder liner–piston ring (CLPR) with different combustion modes should not be ignored.

The influence of surface texturing on the transition of the lubrication regimes between a piston ring and a cylinder liner

2016 ◽  
Vol 18 (8) ◽  
pp. 785-796 ◽  
Author(s):  
Chunxing Gu ◽  
Xianghui Meng ◽  
Youbai Xie ◽  
Di Zhang
Keyword(s):  
Piston Ring ◽  
Surface Texturing ◽  
Cylinder Liner ◽  
Mixed Lubrication ◽  
Textured Surface ◽  
Asperity Contact ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime ◽  
Stribeck Curves

This article employs a mixed lubrication model to investigate the performance of the textured surface. The Jakobsson–Floberg–Olsson model is used to obtain the hydrodynamic support of the textured conjunction, while the calculation of the asperity contact load is based on the load-sharing concept. Based on the simulated Stribeck curves of the smooth surface and the textured surface, comparisons are conducted to study the effect of texturing under different lubrication regimes. It appears that the transition of lubrication regimes is influenced by the texturing parameters and the convergence degrees of conjunction. The presence of textures delays the appearance of the mixed lubrication regime and the boundary lubrication regime.

scholarly journals Study of Tribological Properties of Fullerenol and Nanodiamonds as Additives in Water-Based Lubricants for Amorphous Carbon (a-C) Coatings

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 139
Author(s):  
Shuqing Chen ◽  
Qi Ding ◽  
Yan Gu ◽  
Xin Quan ◽  
Ying Ma ◽  
...  
Keyword(s):  
Amorphous Carbon ◽  
Tribological Properties ◽  
Size Range ◽  
Friction Pair ◽  
Asperity Contact ◽  
Low Concentration ◽  
Contact Loads ◽  
Water Based ◽  
The Coefficient Of Friction ◽  
Sufficient Concentration

The tribological performances of fullerenol and nanodiamonds (NDs) as additives in water-based lubricants for amorphous carbon (a-C) coatings are investigated to avoid disadvantage factors, such as chemical reactions and deformation of particles. The effects of size and additive amount on tribological properties of nanoparticles are studied by rigid nanoparticles within the dot size range. The results show that owing to its small particle size (1–2 nm), fullerenol cannot prevent direct contact of the friction pair at low concentration conditions. Only when the quantity of fullerenol increased to support the asperity contact loads in sufficient concentration did nano-bearings perform well in anti-friction and anti-wear effects. Unlike fullerenol, nanodiamond particles with a diameter of about 5–10 nm show friction-reducing effect based on the nano-bearing effects at ultra-low concentration (0.01 wt.%), whereas particles at higher concentration block the rolling movement, hence increasing the coefficient of friction (COF) and wear. As a result of the effect of difference in size, fullerenol provides a better overall lubrication, but it is hard to reach a friction coefficient as low as NDs even under the optimal conditions.

Piston ring-cylinder liner tribology investigation in mixed lubrication regime: part I-correlation with bench experiment

2015 ◽  
Vol 67 (6) ◽  
pp. 520-530 ◽  
Author(s):  
Lin Ba ◽  
Zhenpeng He ◽  
Lingyan Guo ◽  
Young Chiang ◽  
Guichang Zhang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Sudden Change ◽  
Mixed Lubrication ◽  
Friction Reduction ◽  
Asperity Contact ◽  
Film Rupture ◽  
Frictional Loss ◽  
Content Type ◽  
Oil Film ◽  
Ring Sample

Purpose – The purpose of this paper is to improve the environment and save energy, friction reduction, lower oil consumption and emissions demand that are the chief objectives of the automotive industry. The piston system is the largest frictional loss source, which accounts for about 40 per cent of the total frictional loss in engine. In this paper, the reciprocating tribometer, which is updated, was used to evaluate the friction and wear performances. Design/methodology/approach – An alternate method is introduced to investigate the effect of reciprocating speed, normal load, oil pump speed and ring sample and oil temperature on friction coefficient with the ring/liner of a typical inline diesel engine. The orthogonal experiment is designed to identify the factors that dominate wear behavior. To understand the correlations between friction coefficients and wear well, different friction coefficient results were compared and explained by oil film build-up and asperity contact theory, such as the friction coefficient over a long period and averaged the friction coefficient over one revolution. Findings – The friction coefficient changes little but fluctuates with a small amplitude in the stable stage. The sudden change of frequency, load and stroke will lead to the oil film rupture. The identification for the factors that dominates the wear loss is ranged as F (ring sample) > , E (oil sample) > , B (stroke) > , D (temperature) > , A (load) > , G (liner) > and C (frequency). Originality/value – This paper develops and verifies a methodology capable of mimicking the real engine behavior at boundary and mixed lubrication regimes which can minimize frictional losses, wear, reduce much work for the experiment and reduce the cost. The originality of the work is well qualified, as very few papers on a similar analysis have been published, such as: The friction coefficient values fluctuating in the whole stage may be caused by the vibration of the system; suddenly, boundary alternation may help the oil film to form the lubrication; and weight loss mainly comes from the contribution of the friction coefficient value fluctuation. The paper also found that the statistics can gain more information from less experiment time based on a design of experiment.

A Mixed Elastohydrodynamic Lubrication Model With Asperity Contact

1999 ◽  
Vol 121 (3) ◽  
pp. 481-491 ◽  
Author(s):  
Xiaofei Jiang ◽  
D. Y. Hua ◽  
H. S. Cheng ◽  
Xiaolan Ai ◽  
Si C. Lee
Keyword(s):  
Contact Pressure ◽  
Contact Area ◽  
Rough Surfaces ◽  
Elastohydrodynamic Lubrication ◽  
Load Ratio ◽  
Mixed Lubrication ◽  
Successful Implementation ◽  
Asperity Contact ◽  
Contact Ratio ◽  
Lubrication Performance

Most machine elements, such as gears and bearings, are operated in the mixed lubrication region. To evaluate lubrication performance for these tribological components, a contact model in mixed elastohydrodynamic lubrication is presented. This model deals with the EHL problem in the very thin film region where the film is not thick enough to separate the asperity contact of rough surface. The macro contact area is then divided into the lubricated area and the micro asperity contact areas by the contacted rough surfaces. In the case when asperity to asperity contact is present, Reynolds equation is only valid in the lubricated areas. Asperity contact pressure is determined by the interaction of two mating surfaces. The applied load is carried out by the lubricant film and the contacted asperities. FFT techniques are utilized to calculate the surface displacement (forward problem) by convolution and the asperity contact pressure (inverse problem) by deconvolution for non-periodic surfaces. With the successful implementation of FFT and multigrid methods, the lubricated contact problem can be solved within hours on a PC for the grids as large as one million nodes. This capability enables us to simulate random rough surfaces in a dense mesh. The load ratio, contact area ratio and average gap are introduced to characterize the performance of mixed lubrication with asperity contacts. Discussions are given regarding the asperity orientation as well as the effect of rolling-sliding condition. Numerical results of real rough topography are illustrated with effects of velocity parameter on load ratio, contact ratio, and average gap.

Modeling of Axial and Circumferential Ring Pack Lubrication

2001 ◽  
Author(s):  
Mikhail A. Ejakov
Keyword(s):  
Hydrodynamic Lubrication ◽  
Three Dimensional ◽  
Cylinder Liner ◽  
Mixed Lubrication ◽  
Contact Boundary ◽  
Asperity Contact ◽  
Oil Viscosity ◽  
Friction Forces ◽  
Crank Angle ◽  
Ring Pack

Abstract The ring-pack lubrication is a complicated physical process involving multiple physical phenomena. This paper presents an attempt to model the ring-pack lubrication in three-dimensional space, considering the ring-bore structure interaction, bore distortion, ring-twist, piston secondary motion, non-Newtonian lubricant behavior, and ring/bore asperity contacts. The physics of the model includes the interface between the structure of the ring, oil lubricant, and the structure of the cylinder liner. The ring is modeled as a three-dimensional FEA model with the nodes along the ring circumference. The ring face orientation changes circumferentially depending on ring geometry as well as piston tilt angle and three-dimensional ring twist angle at every crank angle degree. The oil lubrication is modeled with the Reynolds equation with shear thinning and temperature dependent oil viscosity and with or without the flow factors. The cylinder liner description allows three-dimensional bore distortion and ring/liner asperity contact to be modelled. The key of the analysis is solving simultaneously at every crank angle increment a set of coupled linear and non-linear equations of ring structure, ring face lubrication, bore distortion, and asperity contact. The model predicts variations of the ring-pack lubrication in the axial and circumferential directions. Using the hydrodynamic lubrication model coupled with the asperity contact model allows calculations of the friction forces due to asperity contact (boundary and mixed lubrication) and oil film interactions (hydrodynamic and mixed lubrication). The transition from hydrodynamic lubrication to boundary lubrication through mixed lubrication is determined interactively based on ring / liner surface properties, ring loads, and lubrication properties. The new friction sub-module calculates axial and circumferential variation of both types of friction forces as well as total friction. The asperity contact induced friction forces and asperity contact pressure can further be used for ring wear calculations. The developed model has been applied to determine the performance of a production engine ring-pack. The influence of different phenomena affecting the ring-pack performance has been analyzed and compared.

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