Optimised textured surfaces with application in piston ring/cylinder liner contact

Abstract

This item was submitted to Loughborough's Institutional Repository (https://dspace.lboro.ac.uk/) by the author and is made available under the following Creative Commons Licence conditions.For the full text of this licence, please go to: http://creativecommons.org/licenses/by-nc-nd/2.5/ In: Tribology and Dynamics of Engine and Powertrain: Fundamentals, Applications and Future Trends, Edited by H. Rahnejat, Woodhead Publishing, 2010, pp. 470-517, ISBN: 978-1-84569-993-2 Chapter 14 Optimised Textured Surfaces with Application in Piston-Ring/Cylinder Liner Contact R. RAHMANI, Loughborough University, UK A. SHIRVANI and H. SHIRVANI, Anglia Ruskin University, UK Abstract: The application of textured surfaces in tribology has recently gained a huge momentum. In this chapter, a systematic approach to investigate the maximum outcomes from employing such surfaces is introduced with an insight into their application in internal combustion engines. A combination of various affecting parameters on the tribological performance of such surfaces is studied and the optimum results were introduced. The effect of employing such optimised textures in enhancing the lubrication condition in piston ring/cylinder liner contact is also studied.Key words: surface texturing, piston ring/cylinder liner contact, optimisation, slider bearings IntroductionIn general, friction is inherent to and is produced between bodies in contact with relative motion. Friction tends to oppose this relative motion between the bodies through loss of energy mostly in the form of heat, mechanical vibration and noise. Therefore, in most cases, friction is an unfavourable phenomenon. In some cases introduction of friction is desired, for example in order to slow down a moving car, the brakes are used to reduce the existing kinetic energy in the wheels by means of producing frictional losses. However, in most of the cases, facilitating this relative motion between bodies is of concern and as a result, one needs to overcome friction so that the relative motion pursues with a minimal loss of energy.Excessive friction can cause damage to the surfaces in contact in several ways and as a result make them wear. Since the surfaces are damaged due to wear, the rate of energy dissipation due to friction increases and consequently amplifies the rate of wear itself (see Chapter 2).The reason for the existence of friction is mainly that in reality, there is no perfect smooth surface. In fact, surfaces have a degree of roughness in the form of small 'hills' and 'valleys' no matter how well they are prepared. When two surfaces, which are in contact with each other, are put into relative motion, the asperities on the In: Tribology and Dynamics of Engine and Powertrain: Fundamentals, Applications and Future Trends, Edited by H. Rahnejat, Woodhead Publishing, 2010, pp. 470-517, ISBN: 978-1-84569-993-2 opposing surfaces become locked hence inducing friction as initially proposed by Amontons for onset of motion and later under kinetic conditions by Coulomb (see Chapter 2). W...

Influence of surface texture shape, geometry and orientation on hydrodynamic lubrication performance of plane‐to‐plane slider surfaces

“…However, they indicated that the hierarchy of parameters may vary slightly under different loading conditions. In a tribological study on piston ring/cylinder liner contact, Rahmani et al investigated and optimised negative and positive type texture with different shapes in hydrodynamic lubrication. The increase of textures on the bearing surface is beneficial, and the optimised textures depend on the type, shape and geometry of the textures on the bearing surface.…”

Reducing in-cylinder parasitic losses through surface modification and coating

“…The method of analysis has been fully described by Balakrishnan et al 10 Analytical work by Spencer et al12 with different cross-hatch honed liners also showed that the fabricated grooves themselves act as microwedges. As already noted in the introduction, a series of analytical simulations by Rahmani et al 21 for the case of compression ring-cylinder bore contact has shown that lasertextured dimples of a conical geometry with a certain distribution, spacing and depth yield the highest load-bearing capacity, as well as reduced friction. These predictions generally agree with various experimental studies for different conjunctions.…”

“…Rahnejat et al 15 also reported a similar decrease in friction through the use of laser-ablated patterned features on the surface of the advanced coated cylinder liners in the TDC region, which are used for motor racing applications. A comprehensive analysis of various surface texture features has been given by Rahmani et al 21 Increasingly, high-performance engines and components are constructed from light alloy materials. This can drastically reduce the inertial forces developed.…”

A Numerical Model to Study the Role of Surface Textures at Top Dead Center Reversal in the Piston Ring to Cylinder Liner Contact

“…However, the study did not take into account any asperity interactions in the determination of generated friction, which would be important at reversal points [18,19]. Rahmani et al [33][34] used an analytic method to optimise the feature type and pattern for a flat sliding ring. They showed that for such geometry a dimple feature of certain depth and spacing ratio yielded optimum conditions.…”