Experimental Investigation of Partial Laser Surface Texturing for Piston-Ring Friction Reduction

Ryk, G.; Kligerman, Y.; Etsion, I.; Shinkarenko, A.

doi:10.1080/05698190500313544

Cited by 142 publications

(97 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These were in line with the predictions made by Ronen et al [21]. However, Ryk et al [30] recommended that a more sophisticated analysis should include comparisons with real barrel shaped untextured ring profile. The implementation of the partially textured flat face rings in the real engine conditions by Etsion and Sher [2] has nevertheless shown that the textured flat face rings out-perform the untextured barrel shaped ones in terms of BSFC by ~1 to 4% depending on the engine loading and speed conditions.…”

Section: Introductionsupporting

confidence: 75%

“…They advocated partial texturing of ring's inlet chamfered faces with a pattern of dimples. Ryk et al [29][30][31] investigated the effect of employing optimised textured patterns by Ronen et al [21] in slider rig test, designed to reproduce the sliding motion of piston ring/cylinder liner contact. They employed rings with relatively flat face-width and mildly chamfered edges.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Morris

Rahmani

Rahnejat

et al. 2015

Journal of Tribology

View full text Add to dashboard Cite

Minimisation of parasitic losses in the internal combustion engine is essential for improved fuel efficiency and reduced emissions. Surface texturing has emerged as a method palliating these losses in instances where thin lubricant films lead to mixed or boundary regimes of lubrication. Such thin films are prevalent in contact of compression ring to cylinder liner at piston motion reversals because of momentary cessation of entraining motion. The paper provides combined solution of Reynolds equation, boundary interactions and a gas flow model to predict the tribological conditions, particularly at piston reversals. This model is then validated against measurements using a floating liner for determination of in-situ friction of an engine under motored condition. Very good agreement is obtained. The validated model is then used to ascertain the effect of surface texturing of the liner surface during reversals. Therefore, the paper is a combined study of numerical predictions and the effect of surface texturing. The predictions show that some marginal gains in engine performance can be expected with laser textured chevron features of shallow depth under certain operating conditions. Keywords: A c c e p t e d M a n u s c r i p t N o t C o p y e d i t e d

show abstract

Section: Introductionsupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

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

Morris

Rahmani

Rahnejat

et al. 2015

Journal of Tribology

View full text Add to dashboard Cite

show abstract

“…Other researchers have already shown improvements in friction reduction by partial texturing of the flat contacting land of a chamfered piston compression ring with dimples. 16,20,44,45 This represented an option for the current study.…”

Section: Results Of Textured Surfacesmentioning

confidence: 99%

Reducing in-cylinder parasitic losses through surface modification and coating

Howell-Smith

Rahnejat

King

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part D:

View full text Add to dashboard Cite

Friction constitutes nearly one fifth of all engine losses. The main contributory source of frictional losses in most engines is the piston-cylinder system, accounting for nearly half of all the parasitic losses. Minimisation of this is essential for improved fuel efficiency and reduced emissions, which are the main driving forces in engine development. The tribology of piston-cylinder conjunctions is, however, transient in nature. This means that various palliative actions need to be undertaken to suit certain instances during the engine cycle. In general, formation of a coherent film of lubricant of suitable viscosity reduces the chance of boundary interactions for most of the piston cycle. Plateau honing of the cylinder bore surface reduces the 'peakiness' of the surface topography. Furthermore, if regularly spaced grooves are provided on the contacting surface, these grooves can act as reservoirs of lubricant. However, at low sliding speeds, which are typically found during piston motion reversals, lubricant entrainment into the contact either ceases or is significantly reduced. Therefore, at the end of the piston strokes, there is a greater chance of boundary interactions, resulting in increased friction. There is a need to engineer the surface topography in these low-relative-speed regions in a manner conducive to the retention of a lubricant film. Surface texturing by means of laser processing or mechanical indentation at the dead centres are used to produce local reservoirs of lubricant as well as to encourage and direct the flow of lubricant into the contact conjunction. The paper shows that such surface-modifying features improve the engine's output power by as much as 4% over that of the standard cylinder bore surface. To reduce wear and scuffing, particularly at the top dead centre, hard coatings can also be used. However, smooth surfaces and the generally oleophobic nature of hard coatings can increase the chance of adhesion, particularly at low sliding speeds. This means that prevention of wear does not necessarily lead to improved fuel efficiency. Furthermore, it is necessary to determine the geometry of the textured patterns in order to avoid the leakage of oil from the ring-pack conjunctions, which can result in increased emissions as well as lubricant degradation and depletion.

show abstract

“…Etsion et al [11][12][13][14][15][16][17][18] also contributed to the field through a range of insightful experimental observations. Notably, they demonstrated the importance of aspect ratio and other co-dependent geometric parameters used to describe a textured pattern in controlling the friction performance of a microtextured bearing.…”

Section: Introductionmentioning

confidence: 99%

The Transient Friction Response of a Laser-Textured, Reciprocating Contact to the Entrainment of Individual Pockets

et al. 2016

View full text Add to dashboard Cite

To shed light on the mechanisms with which surface texture improves the tribological performance of piston-liner contacts, we have measured the transient friction response as individual pockets pass through a reciprocating sliding contact. Tests were performed at different sliding speeds and results compared to those from a non-textured, reference specimen under different lubrication regimes. At low speed when the contact is in the boundary regime, friction force falls abruptly as each pocket leaves the contact zone, before gradually returning to an approximately steady-state value. This suggests that each pocket acts to temporarily increase the film thickness, which then decays to its non-textured value as oil is squeezed out. At higher speeds, friction is seen to reduce in a stepwise fashion, since the period between pockets being entrained is less than the time taken for the film to decay. In addition, friction results obtained when the contact is operating in the middle of the mixed regime point to a temporary film thickness collapse as the pocket enters the contact, and this agrees with recent modelling predictions. At higher speeds, the compound effect of successive pockets is to shift the contact to the right on Stribeck curve. These results imply that each pocket gives rise to an increase in film thickness that is both short-lived and small in magnitude (we estimate a few tens of nm). However, the resulting effect on friction can be significant (up to 82 % in this study) for two reasons: (1) provided the pocket frequency is sufficiently high, each successive pocket entrainment builds the film up without there being time for it to reduce back to its steady-state value; (2) when the contact is in the mixed regime, the Stribeck curve is at its steepest and friction is therefore most sensitive to film thickness changes. This has important practical implications in that pocket spacing on piston liners should be varied as a function of reciprocating sliding speed.

show abstract

Experimental Investigation of Partial Laser Surface Texturing for Piston-Ring Friction Reduction

Cited by 142 publications

References 14 publications

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

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

Reducing in-cylinder parasitic losses through surface modification and coating

The Transient Friction Response of a Laser-Textured, Reciprocating Contact to the Entrainment of Individual Pockets

Contact Info

Product

Resources

About