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%.

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.

Experimental research on the frictional performance of real laser-textured cylinder liner under different lubrication conditions

2021 ◽  
pp. 146808742199529
Author(s):  
Bifeng Yin ◽  
Bo Xu ◽  
Hekun Jia ◽  
Xijun Hua ◽  
Yonghong Fu
Keyword(s):  
Friction Force ◽  
Piston Ring ◽  
Hydrodynamic Lubrication ◽  
Cylinder Liner ◽  
Mechanical Efficiency ◽  
Laser Surface Texturing ◽  
Laser Texturing ◽  
Friction Coefficients ◽  
Lubrication Conditions ◽  
Ring Pair

Laser surface texturing technology including the steps of surface pre-processing, laser texturing, and surface post-polishing was utilized to process typical micro-dimples(diameter 50 μm, depth 8 μm, and area ratio 10%) on the cylinder liner surface in a production engine. By conducting the reciprocating friction tests on a friction-wear tester, the instantaneous friction force of the real cylinder liner-piston ring pair was measured for comparing the tribological performance of plateau-honed cylinder liner and laser-textured cylinder liner. The testing results showed that under different lubrication conditions, laser texturing cylinder liner could effectively reduce the friction force, especially the peak force around the reciprocating stroke ends of ring/liner pair. Within a reciprocating stroke, the average friction coefficients of the laser-textured cylinder liner-piston ring pair decrease by approximately 18.6%–37.6% under low temperature oil bath condition dominated by hydrodynamic lubrication, while the friction coefficients decrease by approximately 1.8%–6.1% under high temperature oil bath condition dominated by mixed lubrication compared with these of the plateau-honed cylinder liner-piston ring pair. This indicates that laser texturing cylinder liner with appropriate micro structures could enhance the hydrodynamic effects and reduce the friction of ring/liner system, which is conducive to improving the engine mechanical efficiency and the application of low-friction design on production engine.

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.

Improvements in premixed charge compression ignition combustion and emissions with lower distillation temperature fuels

2005 ◽  
Vol 6 (5) ◽  
pp. 433-442 ◽  
Author(s):  
A Sakai ◽  
H Takeyama ◽  
H Ogawa ◽  
N Miyamoto
Keyword(s):  
Diesel Fuel ◽  
Direct Injection ◽  
Cylinder Liner ◽  
Lubricating Oil ◽  
Compression Ignition ◽  
Gas Temperature ◽  
Compression Stroke ◽  
Charge Mixture ◽  
Rate Of Heat Release ◽  
Wall Wetting

The charge mixture in a premixed charge compression ignition (PCCI) engine with direct in-cylinder injection early in the compression stroke is still heterogeneous even at the compression end. Direct injection of a low-volatility fuel, such as diesel fuel, early in the compression stroke results in adhesion of unevaporated fuel on the cylinder liner wall. It may be possible to improve both mixture formation and homogeneity, and decrease wall wetting by using higher-volatility fuels with distillation temperatures lower than the in-cylinder gas temperature early in the compression stroke. This research addressed the potential for improvements in early direct injection type PCCI combustion with a higher-volatility fuel, experimentally and computationally. A normal heptane + isooctane blended fuel with ignitability similar to diesel fuel in PCCI operation was used as the higher-volatility fuel. The experimental results showed that the deterioration in thermal efficiency that occurs with advanced injection timings with ordinary diesel fuel could be eliminated with the higher-volatility fuel without significantly altering the total hydrocarbons (THC) and CO emissions. With early injection timings, the rate of heat release with diesel fuel is smaller than with higher-volatility fuels. This result suggests that with diesel fuel there is significant fuel adhesion to the cylinder liner wall and also absorption into the lubricating oil.

Simulation of Altitude Influence on Piston Ring Movement and Blow-By Effects in Piston Engines (Keynote)

2003 ◽  
Author(s):  
Sylvester Abanteriba
Keyword(s):  
Combustion Chamber ◽  
Piston Ring ◽  
Cylinder Liner ◽  
Lubricating Oil ◽  
Axial Position ◽  
Piston Engine ◽  
Piston Rings ◽  
Ability To Act ◽  
Effective Seal ◽  
The Impact

The compression and oil rings of the piston engine play a very important role in the performance and reliability of the piston engine. The rings are required to accomplish three main distinct tasks: 1. Sealing the combustion chamber gas from the crankcase to eliminate blow-by phenomenon, which constitutes the flow of some of the contents of the combustion chamber into the crankcase. 2. Proper distribution of the lubricating oil film over the piston skirt and cylinder liner. 3. Transfer of heat from piston to cylinder liner. Unfortunately the piston ring pack contributes to the highest proportion of the frictional losses in the engine and is more prone to high wear rates. In the engine, the compression rings are designed to provide effective sealing of the crankcase against the gases from the combustion chamber. The oil-rings provide an effective means of distributing the lubricating oil over the cylinder liner while keeping it from flowing into the combustion chamber. The ability of the compression rings to serve as a gas seal depends on their axial position within the groove. The ring needs to be in contact with the lower flank in order to provide the requisite sealing effect. Once the ring lifts itself from the lower flank its ability to act as an effective seal is compromised. The axial motion of the piston rings during the operation of the engine engenders blow-by and therefore has deteriorating effect on the engine performance. Not much work has, hereto, been done to study the impact of altitude on the movement of the piston rings and hence the blow-by phenomenon. This papers presents a simulation model to investigate this effect.

Numerical Simulation on the Lubrication Performance of Surface Textured Piston Rings

2011 ◽  
Vol 199-200 ◽  
pp. 734-738 ◽  
Author(s):  
Qiu Ying Chang ◽  
Xian Liang Zheng ◽  
Qing Liu
Keyword(s):  
Numerical Simulation ◽  
Film Thickness ◽  
Friction Force ◽  
Friction And Wear ◽  
Piston Ring ◽  
Hydrodynamic Lubrication ◽  
Cylinder Liner ◽  
Area Density ◽  
Oil Film ◽  
Lubrication Performance

Surface texturing has been successfully employed in some tribological applications in order to diminish friction and wear. This technology may be used in a piston ring to decrease the friction and wear of the contact between a piston ring and cylinder liner. A numerical simulation of lubrication between a surface textured piston ring and cylinder liner based on the hydrodynamic lubrication theory was conducted. The influence of surface texture parameters on piston ring lubrication performance was obtained by solving the mathematical equations with a multi-grid method. The results show that under the micro-dimple area density of 5%-40% the minimum oil film thickness increases and the dimensionless friction force decreases with the increasing of it. Under the dimple area density of 40%-60%, the minimum oil film thickness and the dimensionless friction force change slightly. Under various dimple area densities the optimum dimple depth at the given working condition in this paper is about 5µm.

Piston ring–cylinder liner lubrication analysis in a CO2 refrigeration reciprocating compressor

2011 ◽  
Vol 225 (11) ◽  
pp. 2638-2648 ◽  
Author(s):  
B Yang ◽  
Y Zhao
Keyword(s):  
Film Thickness ◽  
Friction Force ◽  
Piston Ring ◽  
Leading Edge ◽  
Cylinder Liner ◽  
Stress Factors ◽  
Maximum Magnitude ◽  
Reciprocating Compressor ◽  
Oil Film ◽  
Effect Of Surface

A simulation model is developed for the piston ring–cylinder liner lubrication problem in a CO2 refrigeration reciprocating compressor. Patir and Cheng’s modified Reynolds equation including pressure flow factors, shear flow factors, and shear stress factors is used to consider the effect of surface roughness on lubrication. The piston ring is assumed to be fully flooded at the leading edge, and both the cavitation case and fully flooded case are considered at the trailing edge. Modified Reynolds boundary condition is employed. The simulation results show that, the minimum oil film thickness has a maximum magnitude in the middle stroke region for downward stroke and upward stroke. In the vicinity of the dead centres, the magnitude of the friction force is much higher than that in the middle stroke region. The oil film pressure distribution along the piston ring thickness at different specified crank angles is indicated. The effects of ring thickness, crown height on minimum oil film thickness, and friction force are also investigated.

scholarly journals The Split Friction Model - Introducing Mixed Lubrication to Curling

2021 ◽  
Author(s):  
Martin Ziegler
Keyword(s):  
Friction Force ◽  
Normal Force ◽  
Lateral Force ◽  
Friction Model ◽  
Mixed Lubrication ◽  
Stribeck Curve ◽  
Static Case ◽  
Friction Forces ◽  
Gyroscopic Precession ◽  
Centripetal Forces

Abstract In general, the curling stone is subject to mixed lubrication, resulting in the characteristic Stribeck -curve. As velocity increases, the friction force falls quadratically just to rise linearly yet almost flat after the minimum. In the case of a rotating curling stone this results in a torque. Due to isotropy , the lateral force arises as a delta of asymmetric friction forces opposite to the centripetal forces. \par This in turn allows a split friction model that splits up the quadratic curve into two rather constant values for the friction force on the advancing and the retreating side below a critical velocity difference of these sides: the flee force on the advancing side must not exceed the normal force of the retreating side. Only then a curl can happen. This explains why a stone curls towards the end of the throw. \par Following basic static considerations, the stone may theoretically rest on up to three points during a throw. Each single static case is investigated. These results are discussed with additional heuristic calculations that involve Scratch-Theory. Lastly, the influence of gyroscopic precession yields a graph that reflects established experimental observations: A desired flat curve within deviations ranging from 0.80 to 1.02 meter for up to 20 rotations just to rise linearly up to 2 meters for 80 rotations.

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