Combined measurement and simulation of piston ring cylinder liner contacts with a reciprocating long-stroke tribometer

Michelberger, Björn; Jaitner, Dirk; Hagel, Andreas; Striemann, Patrick; Kröger, Benjamin; Leson, Andreas; Lasagni, Andrés Fabían

doi:10.1016/j.triboint.2021.107146

Cited by 13 publications

(19 citation statements)

References 33 publications

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“…3 Simulation model and tools for piston and piston ring dynamic tribological contact analysis the friction calculation in the EHD contacts a mixed friction model [10,11] is used which considers boundary and viscous friction. This model was calibrated for the different piston ring cylinder liner contacts and their operating conditions by a combined measurement and simulation approach [12]. For this, a reciprocating long-stroke tribometer test bench is simulated for different tribological pairs and compared against corresponding measurements.…”

Section: Piston Assembly Friction Simulationmentioning

confidence: 99%

Combined experimental and simulative approach for friction loss optimization of DLC coated piston rings

Götze

Jaitner²

2022

Automot. Engine Technol.

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Piston rings cause significant friction losses within internal combustion engines. Especially the first compression ring, which is pressed onto the liner by high cylinder pressure, contributes significantly to the total friction loss of the piston assembly. The tribological behavior of the oil scraper ring is mainly related to the pretensioning force and can lead to high losses even at low and idle speed. Due to this, there is always a markable risk of wear for the contact surfaces of the piston rings and the cylinder. “Diamond-like carbon” coatings on the surface of the piston rings can prevent wear and are able to reduce friction in the ring-liner-contact. The purpose of this work was to investigate the tribological benefit of this coating-system on the compression and oil scraper ring. Experimental studies were carried out on a fired single-cylinder engine using the Indicated Instantaneous Mean Effective Pressure-method (IIMEP) for the crank angle-resolved detection of the piston assembly’s friction force. To be able to determine the component-related fractions of the friction loss and to quantify the hydrodynamic and asperity related parts locally and time dependent, an EHD/MBS model of the engine was created in AVL EXCITE and a simulative investigation was performed. This simulation was validated by the experimental work and provided detailed information about the individual contact conditions and gap height of each tribological contact of the piston group. The combined approach of measurement and simulation enabled the prediction of tribological aspects and performance in parameter studies on a virtual engine test bed.

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Section: Piston Assembly Friction Simulationmentioning

confidence: 99%

Combined experimental and simulative approach for friction loss optimization of DLC coated piston rings

Götze

Jaitner²

2022

Automot. Engine Technol.

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“…Similarly, a typical sliding speed of 0.1 m/s is applied for the shear flow factors. With the Cross Correlation Function also calculated, a comparison to previous works 1,12 can now be made knowing both Peklenik numbers. Shown in Figure 9, the derived x direction pressure flow factor, φ x , for the considered power cylinder surfaces and its comparison to Patir and Cheng's 6 statistical model.…”

Section: Resultsmentioning

confidence: 99%

“…This application is largely more accurate when analyzing the full intricacies of three dimensional surface characterizations of a real measured tribological surface. The assumption of a linear auto-correlation function for small decay lengths, λ, may be held true for most engineering surfaces under two dimensions, 1 however this assumption is not held when expanded to three dimensions, especially for the accurate analysis of the piston ring interface.…”

Section: Surface Roughness Directionality Characterizationmentioning

confidence: 99%

“…The study of tribological lubrication flow has become more precedent among power-cylinder components. Although many experimental works exist on experimental aspects of the piston-ring contacts in power-cylinder components, [1][2][3][4] and a little more work has been done on the overall modeling, 5 but little work has been done with regards to the flow in the micro-scale roughness. While a macroscopic study of the engine dynamics is necessary for the success of any fluid bearing component, so are the microscopic interactions when it operates in the boundary lubrication regime.…”

Section: Introductionmentioning

confidence: 99%

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Flow factor modeling of combustion engine ring and cylinder components in mixed hydrodynamic lubrication

Locker

Jackson

Ghaednia³

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part J:

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This work employees the modification of the Reynolds equation for computational efficiency by analyzing rough surfaces in the hydrodynamic flow regime through the use of flow factors. This analysis is aimed towards modeling the surface interactions and pressure variations across power cylinder components of an internal combustion engine, namely the piston ring and cylinder wall. The Patir and Cheng equations are for general surfaces that accounts for the overall effect of roughness and anisotropic structure. However, rough surfaces are not fully characterized by these two parameters and therefore the aim of this paper was to provide flow-factors specific to the cross-hatched cylinder liner surfaces and piston ring interface. These interacting surfaces were measured directly through the use of a profilometer. Average flow factors are derived via full deterministic solution of the Reynolds equation over rough surfaces to model the pressure and shear variations relative to smooth surfaces. These flow factors can then be used to consider the effect of roughness in lubrication problems without deterministically modeling roughness.

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“…Alternatively other studies have used piston ring tribometers to investigate sectioned Top compression ring and liner sections. 21,22,23 These experiments face significant challenges associated with alignment and conformability of ring and liner sections which would only worsen if the same methodology were to be used for a three-piece oil control ring. Söderfjäll et al 12,13,20 presented a hybrid tribometer and floating liner system, built on top of a 6-cylinder engine.…”

Section: Introductionmentioning

confidence: 99%

An experimental investigation of low viscosity lubricants on three piece oil control rings cylinder liner friction

Forder

Morris

King

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part J:

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Reducing energy use and improving engine efficiency is a complex task however to date a continued reduction of lubricant viscosity has proved effective. Reducing viscosity decreases hydrodynamic friction and pumping losses however it can also exacerbate boundary friction losses. Detailed and representative component level experimentation is required to understand the effects of viscosity reduction on friction and opportunity for further optimisation. This paper presents a novel motored reciprocating Tribometer which has been developed to measure the friction between complete cylinder liners and three-piece oil control rings. The system holds individual or multiple rings stationary in a bespoke ring holder and reciprocate the cylinder liner thereby replicates the relative kinematics of the components in service. The new design has many operational advantages to identify and benchmark the individual contribution of oil control ring friction including near total isolation of oil ring-cylinder liner bore conjunction, pure rectilinear motion and use of full components without resorting to split liner/ring geometries. The experimental rig is used to measure friction at the three-piece oil control ring- cylinder liner conjunction when lubricated with two low viscosity lubricants. The results show prevalence of mixed regime lubrication across the speeds, temperatures and lubricants investigated. The oil control ring under investigation is shown to operate in mixed regime lubrication and at cold start the introduction of lower viscosity lubricants such as 0W-8 showed higher level of oil control ring-cylinder liner friction in comparison to the 0W-40. The information and experimental facility are of critical use for engine designers when considering the potential contradictory component efficiency behaviour when moving to ultra-low viscosity lubricants.

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Combined measurement and simulation of piston ring cylinder liner contacts with a reciprocating long-stroke tribometer

Cited by 13 publications

References 33 publications

Combined experimental and simulative approach for friction loss optimization of DLC coated piston rings

Combined experimental and simulative approach for friction loss optimization of DLC coated piston rings

Flow factor modeling of combustion engine ring and cylinder components in mixed hydrodynamic lubrication

An experimental investigation of low viscosity lubricants on three piece oil control rings cylinder liner friction

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