Effects of Liner Surface Texturing on Ring/Liner Friction in Large-Bore IC Engines

2006 ◽  
Author(s):  
Rosalind Takata ◽  
Yong Li ◽  
Victor W. Wong
Keyword(s):  
Film Thickness ◽  
Internal Combustion Engines ◽  
Surface Texturing ◽  
Friction Reduction ◽  
Asperity Contact ◽  
Oil Film ◽  
Surface Features ◽  
Flow Factor ◽  
Liner Surface ◽  
Ring Pack

Well-designed surface texturing may be used to reduce ring/liner friction and increase efficiency in internal combustion engines. This study investigated the effects of textures of either grooves or dimples on ring/liner friction, in the hydrodynamic and mixed regimes. Existing MIT models were used to conduct this research. The ring-pack model is based on averaged flow-factor Reynolds analysis, and is used in conjunction with a deterministic model for flow factor calculation. Although this advanced model is applicable in a wide range of cases, the surface textures studied here are very different than a typical liner surface, and can be represented only approximately by the averaged analysis upon which the ring simulation is based. For this reason, this analysis of surface features has focused on a parametric study, the goal of which is to analyze trends relating ring/liner friction to surface parameters, and to make a general evaluation of the potential of surface texturing to reduce ring-pack losses. In the hydrodynamic and mixed regimes, surface texturing affects the fluid pressure in the lubricant between ring and liner, thus affecting the ability of the oil film to support the ring load. If the effect of the texturing is to impede the flow of lubricant, the result will be an increase in oil film thickness. This causes friction reduction in two ways: if asperity contact was present, it is reduced; and the increase in film thickness causes a decrease in shear rate, thus decreasing oil shear stress. It was found that surfaces with both dimpled and grooved textures could cause friction reduction through this mechanism, with deeper features and more transverse groove patterns causing the greatest reduction. Friction also decreased with increasing area ratio (the percentage of the surface that is occupied by the surface features) for both grooves and dimples, and was only slightly dependent on groove width and dimple diameter. Because the effect of the surface texturing is on hydrodynamic effects in the oil, it is strongly coupled with lubricant properties. If surface texturing and lubricant viscosity are optimized together side effects such as oil consumption and wear can be mitigated, while friction can be reduced even further than it is via surface texturing alone. This possibility was also briefly considered in this study.

Modeling the Lubrication, Dynamics, and Effects of Piston Dynamic Tilt of Twin-Land Oil Control Rings in Internal Combustion Engines

1999 ◽  
Vol 122 (1) ◽  
pp. 119-129 ◽  
Author(s):  
T. Tian ◽  
V. W. Wong
Keyword(s):  
Film Thickness ◽  
Internal Combustion Engines ◽  
Three Dimensional ◽  
Internal Combustion ◽  
Asperity Contact ◽  
Combustion Engines ◽  
Ring Groove ◽  
Oil Film ◽  
Oil Transport ◽  
Axial Forces

A theoretical model was developed to study the lubrication, friction, dynamics, and oil transport of twin-land oil control rings (TLOCR) in internal combustion engines. A mixed lubrication model with consideration of shear-thinning effects of multigrade oils was used to describe the lubrication between the running surfaces of the two lands and the liner. Oil squeezing and asperity contact were both considered for the interaction between the flanks of the TLOCR and the ring groove. Then, the moments and axial forces from TLOCR/liner lubrication and TLOCR/groove interaction were coupled into the dynamic equations of the TLOCR. Furthermore, effects of piston dynamic tilt were considered in a quasi three-dimensional manner so that the behaviors of the TLOCR at different circumferential locations could be studied. As a first step, variation of the third land pressure was neglected. The model predictions were illustrated via an SI engine. One important finding is that around thrust and anti-thrust sides, the difference between the minimum oil film thickness of two lands can be as high as several micrometers due to piston dynamic tilt. As a result, at thrust and anti-thrust sides, significant oil can pass under one land of the TLOCR along the bore, although the other land perfectly seals the bore. Then, the capabilities of the model were further explained by studying the effects of ring tension and torsional resistance on the lubrication and oil transport between the lands and the liner. The effects of oil film thickness on the flanks of the ring groove on the dynamics of the TLOCR were also studied. Friction results show that boundary lubrication contributes significantly to the total friction of the TLOCR. [S0742-4795(00)01801-9]

Two-dimensional lubrication study of the piston ring pack

1998 ◽  
Vol 212 (3) ◽  
pp. 215-220 ◽  
Author(s):  
K Liu ◽  
Y. B. Xie ◽  
C. L. Gui
Keyword(s):  
Film Thickness ◽  
Piston Ring ◽  
Cylinder Wall ◽  
Asperity Contact ◽  
Two Dimensional ◽  
Oil Film ◽  
Secondary Motion ◽  
Piston Ring Pack ◽  
Ring Pack ◽  
Piston Ring Lubrication

Based on the two-dimensional average flow model and asperity contact model, a theoretical model for the non-axisymmetrical analysis of piston ring lubrication has been suggested in this paper. The two-dimensional distribution of oil-film thickness between the piston rings and cylinder wall is obtained. Results show that the oil-film thickness along the circumference is non-uniform. Starvation is also considered in the model. The effect of secondary motion of piston assemblies on the lubrication property of the piston ring pack has also been studied.

Mixed Lubrication and Friction Power Loss of Piston Ring Pack

2014 ◽  
Vol 668-669 ◽  
pp. 205-208
Author(s):  
Xiao Ri Liu ◽  
Guo Xiang Li ◽  
Shu Zhan Bai ◽  
Yu Ping Hu
Keyword(s):  
Diesel Engine ◽  
Film Thickness ◽  
Power Loss ◽  
Piston Ring ◽  
Asperity Contact ◽  
Simultaneous Solution ◽  
Oil Film ◽  
Friction Power ◽  
Piston Ring Pack ◽  
Ring Pack

With consideration of asperity contact, the minimum oil film thickness and friction power loss are calculated by simultaneous solution of the dynamics, blow-by and lubrication of piston ring pack. Take the piston ring pack in the first cylinder from the free end of a six-cylinder diesel engine for example, results show that the asperity contact takes place at all of the compression rings and oil ring; the minimum oil film thickness is 1.04μm at the top ring; the total friction loss power is 0.94kW, the top ring accounts for 37.2%, the second ring accounts for 33.0%, the oil ring accounts for 29.8%.

Piston Rings Friction Comparison in a Free Piston and Conventional Crankshaft Engines

2018 ◽  
Author(s):  
Mehar Bade ◽  
Nigel N. Clark ◽  
Terence Musho ◽  
Parviz Famouri
Keyword(s):  
Film Thickness ◽  
Internal Combustion Engines ◽  
Asperity Contact ◽  
Combustion Engines ◽  
Power Losses ◽  
Piston Rings ◽  
Free Piston ◽  
Oil Film ◽  
Frictional Losses ◽  
Free Piston Engine

The conventional internal combustion engines driven by crankshafts and connecting rod mechanisms are restrained by combustion, thermal and mechanical inefficiencies. The Oscillating Free Piston Linear Engine Alternator (OFPLEA) produces electric power with no need to modify the reciprocating motion to rotary motion. In the most common geometry it consists of a linear alternator driven cyclically by one or two internal combustion engines. With the elimination of crankshaft mechanism linkages, the free piston engine offers potential benefits over crankshaft engines in terms of total mechanical losses. A significant proportion of 5% to 12% of total fuel energy in conventional engines is consumed to overcome the frictional losses. This research investigation addresses an analytical and numerical model to simulate the tribological performance of piston rings in an OFPLEA engine. The results are then compared with results from an equivalent conventional crankshaft driven engine. This axisymmetric, mixed lubrication tribological model is developed on the hydrodynamic process defined by Patir and Cheng’s modified Reynolds equation and an asperity contact process as defined by Greenwood and Tripp’s rough surface dry contact model. The asperity contact pressure distribution, hydrodynamic pressure distribution, lubricant oil film thickness, frictional force and frictional power losses are calculated using an explicit finite difference approach. In the absence of spring-dominated OFPLEA system, dissimilarity in the piston motion profile for compression and power stroke exhibited two different oil film thickness peaks. Whereas a similar oil film thickness peaks are observed for conventional engine due to the controlled and stable operation maintained by crankshaft mechanism. The simulation results state that the frictional losses due to piston ring - cylinder liner contact are found to be lower for a free piston engine than for those of a corresponding crankshaft engine. The simulated piston ring frictional power losses are found to be 342.8 W for the OFPLEA system and 382.6 W for the crankshaft engine. Further, an overall system efficiency improvement of 0.6 % is observed for an OFPLEA engine due to these reduced frictional losses from piston rings.

Use of a Micro-Contact Model to Optimize SI Engine’s 3-Piece Oil Ring Profiles Regarding Wear and Lubrication

2002 ◽  
Author(s):  
Eduardo Tomanik ◽  
Andre´ Ferrarese
Keyword(s):  
Film Thickness ◽  
Contact Pressure ◽  
Wear Behavior ◽  
Bench Test ◽  
Asperity Contact ◽  
Oil Consumption ◽  
Tangential Load ◽  
Oil Film ◽  
Operation Temperature ◽  
Contact Pressures

A computer model that addresses the wear behavior by calculating hydrodynamic and asperity contact pressures was used to optimize the running face of three-piece oil control rings. The model incorporates Reynolds equation to calculate the oil film thickness for two sliding surfaces under a given condition (profile and topography of the surfaces, load, speed, lubricant viscosity grade and operation temperature). Prediction of the resultant asperity contact pressures is made by Greenwood-Williamson model. More scraping ring rail profiles are better for oil control, but present more wear due to higher asperity contact pressures. This higher wear can lead to less scraping profile, increasing ring end gap and lower ring tangential load, which deteriorates long term oil consumption control, hence engine durability. In the present work, a relatively simple computer program was used to predict lube oil film thickness and wear for different rail running profiles. Ring wear was assumed to be proportional to the calculated asperity contact pressure. Different rail profiles where the running profiles had a flat portion varying from less than 0.10 mm to higher than 0.20 mm were simulated and then tested in a bench test consisting in an electrical motored engine. Except for the combustion absence, all other engine characteristics were preserved (e.g., stroke, piston-ring pack, lubrication system) in the bench test. The measured oil control ring wear correlated very well with the predicted one. The model allowed the numerical optimization of the running profile of ring rail, which has lower asperity contact pressure, hence wear, but still has a good scraping capability. Two actual ICE tests were also realized. The predicted lower wear of the optimized profile was experimentally confirmed and no differences on LOC were found.

Experimental Investigation of Oil Accumulation in Second Land of Internal Combustion Engines

2005 ◽  
Vol 127 (1) ◽  
pp. 206-212
Author(s):  
T. Icoz ◽  
Z. Dursunkaya
Keyword(s):  
Film Thickness ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Engine Oil ◽  
Combustion Engines ◽  
Oil Consumption ◽  
Oil Accumulation ◽  
Oil Film ◽  
Piston Cylinder ◽  
Total Oil

Blowback of engine oil suspended in combustion gases, when the gas flows from the piston second land back into the combustion chamber, is believed to contribute to oil consumption and hydrocarbon emissions in internal combustion engines. Oil accumulation in the region between top and second compression rings is a factor that influences this phenomenon. The effects of individual parameters, such as oil film thickness and viscosity, however, have still not been understood. The present study was aimed at constructing an experimental setup to study the effect of oil film thickness on oil accumulation in the second land of internal combustion engines. Due to the inherent difficulties of experimentation on production engines, a modeled piston-cylinder assembly was constructed. Total oil accumulation in the modeled second land after a single piston stroke was measured and compared to oil consumption in operating engines.

scholarly journals Modeling the Fatigue Wear of the Cylinder Liner in Internal Combustion Engines during the Break-In Period and Its Impact on Piston Ring Lubrication

Lubricants ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 89
Author(s):  
Chongjie Gu ◽  
Renze Wang ◽  
Tian Tian
Keyword(s):  
Internal Combustion Engines ◽  
Cylinder Liner ◽  
Internal Combustion ◽  
Asperity Contact ◽  
Combustion Engines ◽  
Fatigue Wear ◽  
Wear Model ◽  
Surface Finishes ◽  
Liner Surface ◽  
Piston Ring Lubrication

In internal combustion engines, a significant portion of the total fuel energy is consumed to overcome the mechanical friction between the cylinder liner and the piston rings. The engine work loss through friction gradually reduces during the engine break-in period, as the result of liner surface topography changes caused by wear. This work is the first step toward the development of a physics-based liner wear model to predict the evolution of liner roughness and ring pack lubrication during the break-in period. Two major mechanisms are involved in the wear model: plastic deformation and asperity fatigue. The two mechanisms are simulated through a set of submodels, including elastoplastic asperity contact, crack initiation, and crack propagation within the contact stress field. Compared to experimental measurements, the calculated friction evolution of different liner surface finishes during break-in exhibits the same trend and a comparable magnitude. Moreover, the simulation results indicate that the liner wear rate or duration of break-in depends greatly on the roughness, which may provide guidance for surface roughness design and manufacturing processes.

An analytical study of tribological parameters between piston ring and cylinder liner in internal combustion engines

2016 ◽  
Vol 230 (4) ◽  
pp. 329-349 ◽  
Author(s):  
Mohamed Kamal Ahmed Ali ◽  
Hou Xianjun ◽  
Richard Fiifi Turkson ◽  
Muhammad Ezzat
Keyword(s):  
Film Thickness ◽  
Internal Combustion Engines ◽  
Piston Ring ◽  
Cylinder Liner ◽  
Combustion Engines ◽  
Oil Viscosity ◽  
Oil Film ◽  
Ring Assembly ◽  
Ring Dynamics ◽  
Tribological Parameters

This paper presents a model to study the effect of piston ring dynamics on basic tribological parameters that affect the performance of internal combustion engines by using dynamics analysis software (AVL Excite Designer). The paramount tribological parameters include friction force, frictional power losses, and oil film thickness of piston ring assembly. The piston and rings assembly is one of the highest mechanically loaded components in engines. Relevant literature reports that the piston ring assembly accounts for 40% to 50% of the frictional losses, making it imperative for the piston ring dynamics to be understood thoroughly. This analytical study of the piston ring dynamics describes the significant correlation between the tribological parameters of piston and rings assembly and the performance of engines. The model was able to predict the effects of engine speed and oil viscosity on asperity and hydrodynamic friction forces, power losses, oil film thickness and lube oil consumption. This model of mixed film lubrication of piston rings is based on the hydrodynamic action described by Reynolds equation and dry contact action as described by the Greenwood–Tripp rough surface asperity contact model. The results in the current analysis demonstrated that engine speed and oil viscosity had a remarkable effect on oil film thickness and hydrodynamic friction between the rings and cylinder liner. Hence, the mixed lubrication model, which unifies the lubricant flow under different ring–liner gaps, is needed via the balance between the hydrodynamic and boundary lubrication modes to obtain minimum friction between rings and liner and to ultimately help in improving the performance of engines.

scholarly journals Ultrasonic Measurement for Film Thickness and Solid Contact in Elastohydrodynamic Lubrication

2010 ◽  
Author(s):  
R. S. Dwyer-Joyce ◽  
J. Zhu ◽  
T. Reddyhoff
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Theoretical Models ◽  
Asperity Contact ◽  
Oil Film ◽  
Real Area Of Contact ◽  
Nominal Thickness ◽  
Asperity Contacts ◽  
Mediated Contact ◽  
Ultrasonic Investigation

The reflection of ultrasound can be used to determine oil film thickness from the stiffness of the separating film. However, boundary or mixed film lubrication is a common occurrence in elastohydrodynamic lubricated (EHL) contacts, as the nominal thickness of the separating film approaches the surface asperity height. In this paper an ultrasonic investigation was carried out on the interface between a steel ball sliding on a flat disc as the speed was reduced into the boundary regime. The ultrasonic reflection then depends on the stiffness of the interface that now consists of an oil layer and asperity contacts. To distinguish the stiffness contribution from asperity contact and oil layer, a mixed lubrication model for circular contacts was established. This predicted the lubricant film thickness and proportions of solid and liquid mediated contact. The total stiffness predicted by theoretical models showed a good agreement with experimental measurement for kinematic cases. The model can then be used to extract the proportion of real area of contact, and the oil film thickness, from ultrasonic results.

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