scholarly journals Study of Break-In Process and its Effects on Piston Skirt Lubrication in Internal Combustion Engines

Lubricants ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 98 ◽  
Author(s):  
Zhen Meng ◽  
Linfeng Zhang ◽  
Tian Tian
Keyword(s):  
Internal Combustion Engines ◽  
Rapid Change ◽  
System Optimization ◽  
Internal Combustion ◽  
Quantitative Agreement ◽  
Asperity Contact ◽  
Combustion Engines ◽  
Piston Skirt ◽  
Calculation Results ◽  
Realistic Prediction

The piston skirt is one of the main contributors to the total mechanical loss in internal combustion engines. Usually, the skirt friction experiences a rapid change during the break-in period largely due to the wear of the machine marks or roughness against soft coatings. It is thus important to consider the effect of the change of the roughness for a realistic prediction of the piston skirt friction and system optimization. In this work, an existing model of piston skirt lubrication was improved with the consideration of a breaking in process for the most commonly used triangle machine marks. A new set of flow factors in the averaged Reynolds equation were analytically derived for the trapezoid shape formed after wear of the original triangle shape. A new asperity contact model was developed for the trapezoid shape. The calculation results reflect the trend of friction mean effective pressure (FMEP) during break-in in an engine test and showed quantitative agreement under the same amount of wear.

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.

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]

scholarly journals Estimation of Design Parameters of the Crank-Connecting Rod Mechanism of Engines for Mobile Agricultural Machines

2021 ◽  
Vol 37 ◽  
pp. 00076
Author(s):  
F. Khaliullin ◽  
G. Pikmullin ◽  
A. Nurmiev ◽  
M. Lushnov
Keyword(s):  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Design Model ◽  
Design Parameters ◽  
Combustion Engines ◽  
Connecting Rod ◽  
Mass Model ◽  
Calculation Results ◽  
The Masses ◽  
Lumped Masses

An accurate choice of the design model of the crank-connecting rod mechanism of piston internal combustion engines affects the accuracy of the calculation results and their complexity. At present, most of scientists and technicians choose a two-mass design model to analyze the operation of the crankconnecting rod mechanism. The model considers only the rotational and reciprocating movements of two masses, which are connected by a rigid weightless rod. This model significantly simplifies the calculations, neglects the elastic deformations of the parts of the crank-connecting rod mechanism, and eliminates the need for compiling the equations of dynamics in partial derivatives. However, the model has a number of drawbacks. The calculation results obtained using the two-mass model exhibit significant errors, which mainly depend on the design features of the connecting rod assembly. The paper discusses multi-mass design models, where the connecting rod assembly can comprise several lumped masses located along its length. In this case, the plane-parallel motion of these masses is added. The masses have weightless and absolutely rigid bonds. Forces and moments acting on the piston assembly and the crank are calculated according to the equations compiled. Comparison of the calculation results with the results obtained for a two-mass model can be used to determine errors and choose a design model that provides the required accuracy. The considered design model is of interest to engineers and technicians engaged in the design and calculation of the crank-connecting rod mechanism of piston internal combustion engines.

Numerical Study of Piston Skirt-Liner Lubrication Considering the Effects of Deformation in Internal Combustion Engines

2012 ◽  
Author(s):  
Lipu Ning ◽  
Xianghui Meng ◽  
Youbai Xie
Keyword(s):  
Elastic Deformation ◽  
Internal Combustion Engines ◽  
Numerical Study ◽  
Cylinder Liner ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Surface Geometry ◽  
Piston Skirt ◽  
Lubrication Performance ◽  
Liner System

This paper presents a comprehensive lubrication model for piston skirt-liner system of internal combustion engines. In the model it is included that the effects of the surface roughness, the piston skirt surface geometry, the piston pin offset, the crankshaft offset, and the lubricant viscosity on the piston secondary motion and lubrication performance. Especially, the effects of the thermal and the elastic deformation of the piston skirt and the cylinder liner, and the piston skirt deformations due to the combustion pressure and the piston axial inertia, are considered as the key task in this study. The results show that the combustion force, the working temperature and the piston axial inertia all play important roles in the piston-skirt lubrication. Also, considering the elastic deformation of the piston skirt and the cylinder liner is beneficial to the prediction of piston-skirt lubrication more accurately. The developed program in this study can provide a useful tool for the analysis of the piston-liner system lubrication problem.

Piston dynamics, lubrication and tribological performance evaluation: A review

2018 ◽  
Vol 21 (5) ◽  
pp. 725-741 ◽  
Author(s):  
Cristiana Delprete ◽  
Abbas Razavykia
Keyword(s):  
Power Loss ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Tribological Performance ◽  
Operating Conditions ◽  
Friction Reduction ◽  
Design Parameters ◽  
Combustion Engines ◽  
Piston Skirt ◽  
Secondary Motion

Mechanical power loss of lubricated and bearing surfaces serves as an attractive domain for study and research in the field of internal combustion engines. Friction reduction at lubricated and bearing surface is one of the most cost-effective ways to reduce gas emission and improve internal combustion engines’ efficiency. This thus motivates automotive industries and researchers to investigate tribological performance of internal combustion engines. Piston secondary motion has prime importance in internal combustion engines and occurs due to unbalanced forces and moments in a plane normal to the wrist pin axis. Consequently, piston executes small translations and rotations within the defined clearance during the piston reciprocating motion. Mechanical friction power loss and lubrication at piston skirt/liner and radiated engine noise are dramatically affected by piston secondary dynamics. The lubrication mechanism, piston secondary motion and tribological performance are affected by piston design parameters (piston/liner clearance, wrist pin offset, skirt profile, etc.), lubricant rheology, oil transport mechanism and operating conditions. Therefore, this review is devoted to summarize the synthesis of main technical aspects, research efforts, conclusions and challenges that must be highlighted regarding piston skirt/liner lubrication and piston dynamics and slap.

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