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

Chongjie Gu,Tian Tian,Renze Wang

doi:10.3390/lubricants7100089

Chongjie Gu, Tian Tian + Show 1 more

Open Access

https://doi.org/10.3390/lubricants7100089

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Abstract

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.

Highlights

With the goal of pollution control and reduction of greenhouse gas emissions, it is always important to improve the efficiency of internal combustion engines
The effectiveness of the asperity fatigue model is verified by the comparison between simulation results and experimental results, which show similar trends for engine friction change after break-in wear
The experimental friction measurements are obtained from floating liner engines (FLE)

Summary

Introduction

With the goal of pollution control and reduction of greenhouse gas emissions, it is always important to improve the efficiency of internal combustion engines. A major source of engine friction is the contact system of piston rings and cylinder liners. About 20% of the friction loss is caused by the contact between piston rings and liners [1]. Friction loss and other performance factors, such as engine oil consumption and certain emission parameters, usually experience rapid changes (mostly reduction) before they are stabilized for the rest of the engine life. This initial running period is called the break-in period. The ability to predict the changes during the break-in period allows one to predict engine friction over most of its lifetime

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