Piston Ring Behaviour Simulation Considering Mixed-Lubrication and Flexibility

2005 ◽  
Author(s):  
Adolfo Senatore ◽  
Vincenzo D’Agostino
Keyword(s):  
Piston Ring ◽  
Cylinder Liner ◽  
Mixed Lubrication ◽  
Total Power ◽  
Si Engine ◽  
Automotive Engine ◽  
Ring Shape ◽  
Mixed Lubrication Regime ◽  
Cylinder Bore ◽  
Behaviour Simulation

An important portion of the total power loss in a modem automotive engine is due to piston ring/cylinder bore friction. This paper introduces the results of simulations about the interaction of a SI engine piston ring taking into account the mixed lubrication regime, the ring flexibility in presence of piston approaching motion to the cylinder liner. The friction force calculations show a visible difference between the ring portion interacting with the two cylinder sides (Thrust and Anti-Thrust) due to specific oil film wedges caused by flexibility and piston lateral motion. The effects of engine speed, radial tension, surface roughness and ring shape are also investigable.

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.

Frictional Characteristics of IF-WS2 Nanoparticles in Simulated Engine Conditions

2009 ◽  
Author(s):  
Burak Gullac ◽  
Ozgen Akalin
Keyword(s):  
Piston Ring ◽  
Normal Load ◽  
Mineral Oil ◽  
Test System ◽  
Mixed Lubrication ◽  
Bench Test ◽  
Inorganic Fullerene ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime ◽  
Cylinder Bore

The effect of inorganic fullerene-like (IF) WS2 nanoparticles added to mineral oil which has a potential to reduce engine friction was investigated using a reciprocating piston ring - cylinder bore bench test system. The test system simulates actual engine conditions controlling oil temperature, speed, and normal load. Frictional characteristics of various IF-WS2 nanoparticle concentrations in mineral oil were experimentally analyzed. After a certain period of running in mixed lubrication regime, a significant reduction in friction coefficient was observed when the IF-WS2 formulated oil was used. This reduction remains to some extent with the reference mineral oil even after solvent cleaning. The results show that a thin tribofilm gradually forms on the piston ring and the cylinder bore surfaces that reduce the coefficient of friction in mixed lubrication regime. The effects of lubrication regime, load, speed, temperature and surface roughness on tribofilm formation were also discussed.

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 Mutual Effect of Groove Size and Anisotropy of Cylinder Liner Honed Textures on Engine Performances

2014 ◽  
Vol 966-967 ◽  
pp. 175-183 ◽  
Author(s):  
Mohammed Yousfi ◽  
Sabeur Mezghani ◽  
Ibrahim Demirci ◽  
Mohamed El Mansori
Keyword(s):  
Mutual Effect ◽  
Cylinder Liner ◽  
Texture Features ◽  
Groove Depth ◽  
Oil Consumption ◽  
Hydrodynamic Friction ◽  
Liner Surface ◽  
Ring Pack ◽  
Mixed Lubrication Regime ◽  
Cylinder Bore

The cylinder liner surface texture, widely generated by the honing technique, contributes a lot on engine functional performances (friction, oil consumption, running-in, wear etc.). In order to improve these functional performances, different honing processes are being developed. These different honing processes generate surfaces with various texture features characteristics (roughness, valleys depth, valley width, cross hatch angle, etc.). This paper addresses a comparison of ring-pack friction for cylinder texture with different cross-hatch angles and valley sizes. It takes in consideration the mutual effect of valley depth and honing angle. A numerical model is developed to predict friction within the cylinder ring-pack system in mixed lubrication regime and a morphological method is used to characterize groove depth. The results show the effect of different honing variables (rotation speed, stroke speed and indentation pressure) on cylinder bore surface textures and hydrodynamic friction of the ring-pack system.

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.

A Thermal Elastica Theory of Piston-Ring and Cylinder-Bore Contact

1991 ◽  
Vol 58 (1) ◽  
pp. 141-153 ◽  
Author(s):  
D. C. Sun
Keyword(s):  
Thermal Deformation ◽  
Piston Ring ◽  
Operating Parameters ◽  
Thermal Distortion ◽  
Free Ring ◽  
Automotive Engines ◽  
Ring Shape ◽  
Elastica Theory ◽  
Material Values ◽  
Cylinder Bore

The contact between piston-ring and cylinder-bore is generally nonuniform, due to mechanical and thermal distortion of the bore and manufacturing imperfection in the shape of the free ring. This nonuniform contact problem is treated in the present work that features arbitrarily specified bore shape and free ring shape, and also includes the thermal deformation of the ring and the effect of gas pressure. The problem is solved with the elastica theory, incorporating thermal elasticity, and a complementarity formulation. Solutions are computed using dimensions, material values, and operating parameters representative of those found in automotive engines.

Interactions of Piston Ring Pack With Coated Cylinder Liners of Heavy Duty Diesel Engines

2014 ◽  
Author(s):  
Fabio Araujo ◽  
Luiz de Sá Filho ◽  
Jason Bieneman ◽  
Eduardo Nocera ◽  
Edney Deschauer Rejowski
Keyword(s):  
Piston Ring ◽  
Engine Performance ◽  
Cylinder Liner ◽  
Heavy Duty ◽  
Performance Measurements ◽  
Heavy Duty Diesel ◽  
Cylinder Bore ◽  
Cylinder Liners ◽  
The Impact ◽  
Coated Cylinder

The heavy duty diesel (HDD) engine market continues to strive for improvements in engine efficiency and durability which places ever increasing development demands on the power cylinder unit. One of the methods being developed to help meet these demands is coated cylinder bore technology. By applying a coating to the inner diameter surface of a cylinder liner the wear on the liner can be significantly reduced. The reduction in liner wear is not however the only advantage that this technology can offer. Liner coatings can also offer corrosion protection, reductions in wear on the running surface of the rings, improved scuff resistance, and enable improvements in the efficiency of the engine. New piston ring technologies will be valuable in maximizing these advantages and their contribution will be detailed. The system must be properly designed to take full advantage of all of these opportunities. In this paper both the advantages and difficulties coated liners present will be explored by evaluating the impact on the liner, rings and the fuel consumption. This paper will additionally provide details regarding the different liner coating technologies being developed today. To support these recommendations the system’s performance characteristics will be demonstrated through rig testing and engine performance measurements.

Experimental research on the wall-wetting effects on the frictional property of the cylinder liner–piston ring pair

2021 ◽  
pp. 135065012110240
Author(s):  
Bo Xu ◽  
Bifeng Yin ◽  
Hekun Jia ◽  
Mingliang Wei ◽  
Kunpeng Shi
Keyword(s):  
Friction Force ◽  
Piston Ring ◽  
Cylinder Liner ◽  
Mixed Lubrication ◽  
Lubricating Oil ◽  
Stribeck Curve ◽  
Frictional Property ◽  
Negative Effects ◽  
Wall Wetting ◽  
Ring Pair

The application of novel injection strategies (high-pressure injection, early injection, retarded injection, etc.) in combustion engines has made the wall-wetting problem severer. As the splashed fuel dilutes the lubricating oil, the tribological performance of the cylinder liner–piston ring pair will be affected. In this research, the viscosity and wettability tests were conducted firstly by mixing diesel into lubrication oil. It was found that the dynamic viscosity of the mixture drops with more fuel diluting the oil, and a small quantity of diesel mixed will cause a remarkable decline in lubricant viscosity; also, the contact angle shows a downward trend with the increasing diluting ratio. Then based on several typical diluting ratios, the reciprocating friction tests were carried out to measure the instantaneous friction force of the production ring/liner pair. The experimental results showed that under a mixed lubrication state, the peak friction force of the ring/liner pair occurs around the dead centers, while the minimum force occurs at the middle position of the reciprocating stroke; with more fuel diluting the oil, the bearing capacity of oil film degrades, resulting in the increase of friction force. In addition, the average friction coefficient of the ring/liner pair shows an upward trend with the increasing diluting ratio, and the Stribeck curve moves toward the upper-left, which means the lubrication condition of this pair tends to transit from mixed lubrication to boundary lubrication, causing negative effects on the frictional property of the cylinder liner–piston ring pair. Therefore, the diluting ratio should be controlled under 20%.

scholarly journals FRICTIONAL POWER MINIMIZATION IN PARTIALLY TEXTURED PISTON RING ASSEMBLY

2013 ◽  
pp. 132-136
Author(s):  
AARON. M. ASHWIN ◽  
AKASH SASHIDHAR
Keyword(s):  
Piston Ring ◽  
Surface Texturing ◽  
Laser Surface Texturing ◽  
Total Power ◽  
Exhaust Pipe ◽  
Power Losses ◽  
Automotive Engine ◽  
Frictional Losses ◽  
Ring Assembly ◽  
Brake Power

A significant share i.e. 60% of the total power loss in a modern automotive engine in form of heat, either from the engine surface or the exhaust pipe, of which the friction losses may vary from 18% to 20% and frictional losses are also responsible for about 25% of the fuel consumption. It is noted that almost 80% of the frictional losses are due to the frictional losses in the piston ring assembly (PRA). That leaves less than one quarter of the indicated power in terms of brake power. This paper analyses different methods developed by the automobile industries in order to reduce the friction power losses it may be in form of the development of better lubricants, design and partial laser surface texturing (LST) of the piston rings.

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