Detailed analysis of piston secondary motion and tribological performance

2019 ◽  
Vol 21 (9) ◽  
pp. 1647-1661 ◽  
Author(s):  
Cristiana Delprete ◽  
Abbas Razavykia ◽  
Paolo Baldissera
Keyword(s):  
Piston Ring ◽  
Hydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Tribological Performance ◽  
System Of Nonlinear Equations ◽  
Piston Skirt ◽  
Wide Range ◽  
Secondary Motion ◽  
Piston Ring Pack ◽  
Ring Pack

This article presents a detailed analytical model to evaluate piston skirt tribology under hydrodynamic lubrication. The contribution of the piston ring pack lubrication has been taken into account to study piston secondary motion and tribological performance. A system of nonlinear equations comprising Reynolds equation and force equilibrium is solved to calculate piston ring pack friction force and its moment about wrist pin axis. Instantaneous minimum oil film thickness at piston ring/liner interface has been estimated considering different boundary conditions: full Sommerfeld, oil separation, and Reynolds cavitation and reformation. The ring pack model has capability to be used for a wide range of ring face profiles under boundary and hydrodynamic lubrication. Piston secondary motion is evaluated using lubrication theory and equilibrium of forces and moments, to examine the effect of wrist pin location, piston skirt/liner clearance, and oil rheology. Numerical method and finite difference scheme have been used to define piston eccentricity and hydrodynamic pressure acting over the skirt.

Blow-by and tribological performance of piston ring pack during cold start and warm idle operations

2016 ◽  
Vol 59 (7) ◽  
pp. 1085-1099 ◽  
Author(s):  
Jun Cheng ◽  
XiangHui Meng ◽  
YouBai Xie ◽  
XiaoLi Kong
Keyword(s):  
Piston Ring ◽  
Cold Start ◽  
Tribological Performance ◽  
Piston Ring Pack ◽  
Ring Pack

A Three-Dimensional Model for Piston Ring-Pack Dynamics and Blow-By Gas Flow

2004 ◽  
Author(s):  
Liang Liu ◽  
Tian Tian
Keyword(s):  
Dynamic Behavior ◽  
Gas Flow ◽  
Piston Ring ◽  
Three Dimensional ◽  
Beam Theory ◽  
Ring Structure ◽  
Three Dimensional Model ◽  
Secondary Motion ◽  
Piston Ring Pack ◽  
Ring Pack

A three-dimensional (3D) model for piston ring-pack dynamics and blow-by gas flow was developed to enable more in-depth analyses of the ring-pack performance. This model predicts the 3D dynamic behavior of compression rings and twin-land oil control ring due to the ring’s non-axisymmetric properties, bore distortion and piston secondary motion. Finite element beam theory is used for ring structure calculation. Gas flows along the axial and circumferential directions of the power cylinder system are resolved simultaneously with the ring dynamics. The model was applied to a heavy-duty diesel engine. Particular emphasis was placed on the dynamics of keystone type of top ring, and the stability of the second ring with a twist chamfer and twin-land oil control ring under the influence of piston secondary motion. The variations of the gas pressure and ring dynamic behavior along the circumference are discussed.

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.

Modeling and prediction of the running-in behavior of the piston ring pack system based on the stochastic surface roughness

2019 ◽  
Vol 233 (12) ◽  
pp. 1857-1877
Author(s):  
Chunxing Gu ◽  
Di Zhang
Keyword(s):  
Piston Ring ◽  
Transport Model ◽  
Hydrodynamic Pressure ◽  
Cylinder Liner ◽  
Numerical Approach ◽  
Height Distribution ◽  
Asperity Height ◽  
Liner System ◽  
Piston Ring Pack ◽  
Ring Pack

This paper proposes an efficient numerical approach to predict the initial running-in process of piston ring pack/cylinder liner system. A combined mixed lubrication and wear model coupled with an oil transport model was developed. In order to predict the hydrodynamic pressure efficiently, two improved methodologies, including the Fischer-Burmsister-Newton-Schur (FBNS) approach and the Grid Refinement (GR) strategy, were adopted. Meanwhile, in order to take into account the effect of skewness, Weibull distribution function was adopted to characterize the asperity height distribution. Predicting the wear of cylinder liner was based on the Archard's wear law. The influences of asperity plastic deformation and wear on asperity height distribution were considered. The results show that the developed model can well predict the initial running-in behavior of piston ring pack/cylinder liner system under an engine-like condition.

Analysis of lubrication and friction for a complete piston-ring pack with an improved oil availability model: Part 1: Circumferentially uniform film

1997 ◽  
Vol 211 (1) ◽  
pp. 1-15 ◽  
Author(s):  
M-T Ma ◽  
I Sherrington ◽  
E H Smith
Keyword(s):  
Piston Ring ◽  
Tribological Performance ◽  
Comprehensive Analysis ◽  
Oil Accumulation ◽  
Theoretical Formulation ◽  
Assembly Design ◽  
Ic Engines ◽  
Piston Ring Pack ◽  
Ring Pack ◽  
Availability Model

The study of the tribological performance of piston rings plays an important role in piston assembly design. In this study, a comprehensive analysis of piston-ring pack lubrication has been developed. The model employs a flow-continuity algorithm and considers relative ring locations in the piston-ring pack as well as oil accumulation in front of the ring in determining the oil availability. The computer model is able to predict the effect that bore distortion and ring conformability have on piston-ring performance. (This influence is discussed in Part 2 of the paper). In this part of the paper (Part 1), the theoretical formulation of the model is briefly described. The model is verified through comparison of the calculated ring-liner film thicknesses with those measured experimentally by Hamilton and Moore on a diesel engine. Then some results, obtained under situations where film thicknesses are circumferentially uniform, are presented to simulate a piston-ring pack in a modern petrol engine as an example to demonstrate the capabilities of the model and to show the effects of some important factors on the performance characteristics of the ring pack. The authors have found that the model developed is a robust one which can be used to analyse the tribological performance of ring packs effectively in both circular and distorted cylinder bores of internal combustion (IC) engines.

Predictive tool for frictional performance of piston ring-pack/liner conjunction

2019 ◽  
Vol 13 (3) ◽  
pp. 5513-5527
Author(s):  
J. W. Tee ◽  
S. H. Hamdan ◽  
W. W. F. Chong
Keyword(s):  
Film Thickness ◽  
Mathematical Models ◽  
Piston Ring ◽  
Published Data ◽  
Predictive Tool ◽  
Frictional Losses ◽  
Fundamental Understanding ◽  
Minimum Film Thickness ◽  
Piston Ring Pack ◽  
Ring Pack

Fundamental understanding of piston ring-pack lubrication is essential in reducing engine friction. This is because a substantial portion of engine frictional losses come from piston-ring assembly. Hence, this study investigates the tribological impact of different piston ring profiles towards engine in-cylinder friction. Mathematical models are derived from Reynolds equation by using Reynolds’ boundary conditions to generate the contact pressure distribution along the complete piston ring-pack/liner conjunction. The predicted minimum film thickness is then used to predict the friction generated between the piston ring-pack and the engine cylinder liner. The engine in-cylinder friction is predicted using Greenwood and Williamson’s rough surface contact model. The model considers both the boundary friction and the viscous friction components. These mathematical models are integrated to simulate the total engine in-cylinder friction originating from the studied piston ring-pack for a complete engine cycle. The predicted minimum film thickness and frictional properties from the current models are shown to correlate reasonably with the published data. Hence, the proposed mathematical approach prepares a simplistic platform in predicting frictional losses of piston ring-pack/liner conjunction, allowing for an improved fundamental understanding of the parasitic losses in an internal combustion engine.

Gas flow through the piston ring pack

2018 ◽  
Author(s):  
Petr Veigend ◽  
Gabriela Necasov ◽  
Peter Raffai ◽  
Vclav Åtek ◽  
Jir Kunovsk
Keyword(s):  
Gas Flow ◽  
Piston Ring ◽  
Flow Through ◽  
Piston Ring Pack ◽  
Ring Pack

Lubricant Flow Optimization of Large Two Stroke Marine Diesel Engine Piston Ring Packs

2016 ◽  
Author(s):  
Matthias Stark ◽  
Richard Mittler
Keyword(s):  
Piston Ring ◽  
Superior Performance ◽  
Exhaust Gas ◽  
Oil Consumption ◽  
Major Step ◽  
Oil Transportation ◽  
Lubrication Performance ◽  
Marine Diesel ◽  
Piston Ring Pack ◽  
Ring Pack

Approaching a characterization of different contributors to the lube oil balance of an engine becomes important when aiming at enhancing lubrication performance and reducing its contribution to exhaust gas emissions. It is essential to quantify relevant data helping to determine lubrication losses related to particular tribosystem components. Recent activities focused on rating distinct tribosystem component effects on their contribution to total lube oil consumption and the possibility to most effectively modify those. This paper thus describes the most effective tribosystem component modifications, consisting of the application of a substantially modified piston ring pack and the introduction of lube oil accumulating grooves in order to considerably enhance lubrication performance. A proper prediction of piston ring pack dynamics and tribodynamic effects on the lube oil film is essential to design a superior piston ring pack in terms of an optimized piston running behaviour and lube oil transportation. One major step designing such a ring pack is based on the consequent application of a novel 3D piston ring pack simulation tool to enhance lube oil transportation characteristics and distribution. Lube oil accumulating grooves are introduced to reduce lubrication losses due to so called ring pack spray. The ring pack spray is a result of accumulated lubricant in the pressurized piston ring pack expanding into the scavenge air receiver during the scavenging phase. Mentioned effect was analysed in detail in order to determine the amount of related lubricant losses. Investigations in this context lead to the application of lube oil accumulating grooves and hence can be considered an important design aspect to reduce total lube oil consumption. Tribosystem performance validation was performed on the basis of the application of an SO2 tracing technology on a full scale engine test in order to determine relevant tribosystem component modifications in real time. The sulphur content of fuel and lube oil considerably influences the formation of particulate matter in the exhaust gas, following chemical reactions of sulphur oxidation. Hence detecting SO2 in the exhaust gas is a direct measure to determine the amount of lubricant in the exhaust gas composition. Finally this report demonstrates measurement results describing the superior performance of the modified tribosystem.

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