Impact of Boundary Lubrication Performance of Engine Oils on Friction at Piston Ring-Cylinder Liner Interface

Tamura, Kazushi; Kasai, Moritsugu; Nakamura, Yasuto; Enomoto, Tomoyuki

doi:10.4271/2014-01-2787

Cited by 15 publications

(9 citation statements)

References 12 publications

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“…The typical features of f c0 and f ch against h T demonstrated in Figs. 8(b) and (c) are similar to the measured results by Tamura et al [5] using a floating liner friction tester. They showed that engine oil with a friction modifier, particularly MoDTC additives, exhibited similar mixed lubrication and boundary lubrication friction.…”

Section: Load Capacity and Friction Coefficient When N = 3 Andsupporting

confidence: 88%

“…Typical examples reported are the super-low friction coefficient in water-lubricated SiC-SiC sliders with micro-/nano-order textures after the running-in process [1,2] and the reduction of mixed lubrication friction and transition from boundary lubrication to hydrodynamic lubrication regime of the slider lubricated with alkyl acid phoshate additive oil after the running-in [3,4]. Hydrodynamic friction in reciprocating internal combustion engines was decreased by reducing the base oil viscosity, whereas severe friction at the dead center was mitigated by blending the base oil with additives such as MoDTC [5]. This low friction and high load capacity caused by enhanced viscosity in a surface layer have attracted much research attention from tribologists.…”

Section: Introductionmentioning

confidence: 99%

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Modified Reynolds Equations for Thin Film Lubrication with Saturated High-Viscosity Surface Layer and Lubrication Analysis of Tapered Pad Bearing

Ono

2022

Tribology Online

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This paper presents a modified Reynolds equation for analyzing thin film lubrication with a saturated high-viscosity surface layer on a solid surface. The saturated high-viscosity characteristics of engine oil blended with additives of metallic detergents and friction modifiers were expressed using new viscosity functions with various orders termed "viscosity model 2," which is different from the previous model, termed "viscosity model 1." The viscosity function was then incorporated on the moving surface, and the fluid flow in the bearing gap was determined in a closed-form solution for order numbers N of 2 to 5. Subsequently the modified Reynolds equation was formulated by numerically integrating the flow equation. The modified Reynolds equation was applied to analyze the tapered pad bearing, and different features of the load capacity and friction coefficients from those for viscosity model 1 were clarified. The effects of the order number N, viscosity ratio, bearing length, and high-viscosity layer thickness on the load capacity and friction coefficient were elucidated. It was found that when the order number N was increased to 5, the friction coefficient decreased to a minimal value, subsequently increased to the maximum value, and then decreased to the lowest value with a decrease in the trailing gap.

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Section: Load Capacity and Friction Coefficient When N = 3 Andsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Modified Reynolds Equations for Thin Film Lubrication with Saturated High-Viscosity Surface Layer and Lubrication Analysis of Tapered Pad Bearing

Ono

2022

Tribology Online

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“…As a rule of thumb, upgrading the engine's lubricants can advance the fuel economy and the overall engine's system [163]. A valuable advantage of nanolubricants is their ability to bring down both the fuel consumption and the harmful exhaust emissions of engines.…”

Section: Fuel Economy and Emissionsmentioning

confidence: 99%

Recent Advances in Preparation and Testing Methods of Engine-Based Nanolubricants: A State-of-the-Art Review

et al. 2021

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Reducing power losses in engines is considered a key parameter of their efficiency improvement. Nanotechnology, as an interface technology, is considered one of the most promising strategies for this purpose. As a consumable liquid, researchers have studied nanolubricants through the last decade as potential engine oil. Nanolubricants were shown to cause a considerable reduction in the engine frictional and thermal losses, and fuel consumption as well. Despite that, numerous drawbacks regarding the quality of the processed nanolubricants were discerned. This includes the dispersion stability of these fluids and the lack of actual engine experiments. It has been shown that the selection criteria of nanoparticles to be used as lubricant additives for internal combustion engines is considered a complex process. Many factors have to be considered to investigate and follow up with their characteristics. The selection methodology includes tribological and rheological behaviours, thermal stability, dispersion stability, as well as engine performance. Through the last decade, studies on nanolubricants related to internal combustion engines focused only on one to three of these factors, with little concern towards the other factors that would have a considerable effect on their final behaviour. In this review study, recent works concerning nanolubricants are discussed and summarized. A complete image of the designing parameters for this approach is presented, to afford an effective product as engine lubricant.

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“…Other engine oils, including anti-wear additives and friction modifiers, showed rapid increases in viscosity (of more than 100 times) above a 180 nm film thickness. This significant increase in viscosity, with a decrease in film thickness from more than 100 nm, seems to contribute to fluid lubrication in the otherwise mixed lubrication regimes near dead-center positions, even when a low-viscosity base oil is used [6].…”

Section: Introductionmentioning

confidence: 97%

Modified Reynolds Equations for High Viscosity Surface Layer and Thin Film Lubrication Analysis of Tapered/Tapered Land Bearings as Models of Surface Texture

Ono

2019

Tribology Online

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The development of thin film lubrication theory is vital for future micro-textured lubrication technologies. Therefore, a modified Reynolds equation was derived in this research by incorporating the variable viscosity effect in a tribochemical adsorbed layer. The modified factors of the Reynolds equation were expressed as closed form functions for a one-sided viscosity function determined from the measured effective viscosity. Using the one-dimensional modified Reynolds equation, the load capacity and friction coefficients of micro-tapered/tapered land bearings as texture models were numerically investigated. By performing a parametric study with different viscosity ratios (10 and 100), taper lengths (10, 50, and 250 µm), taper angles, and land length ratios and a surface layer thickness of 10-nm, it was found that a high load capacity and an extremely low friction coefficient of less than 10 -4 on the stationary surface could be achieved with a bearing gap of a few tens of nanometers. Since the surface height irregularities between the textures can be compensated for by the elastic deformation caused by high pressures, the lubrication regime in a parallel textured slider can be realized if the roughness heights on the mating surfaces are reduced to less than the bearing gap, using the running-in process.

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Impact of Boundary Lubrication Performance of Engine Oils on Friction at Piston Ring-Cylinder Liner Interface

Cited by 15 publications

References 12 publications

Modified Reynolds Equations for Thin Film Lubrication with Saturated High-Viscosity Surface Layer and Lubrication Analysis of Tapered Pad Bearing

Modified Reynolds Equations for Thin Film Lubrication with Saturated High-Viscosity Surface Layer and Lubrication Analysis of Tapered Pad Bearing

Recent Advances in Preparation and Testing Methods of Engine-Based Nanolubricants: A State-of-the-Art Review

Modified Reynolds Equations for High Viscosity Surface Layer and Thin Film Lubrication Analysis of Tapered/Tapered Land Bearings as Models of Surface Texture

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