Mapping lubricating film thickness, film extent and ring twist for the compression-ring in a firing internal combustion engine

Fatjo, Gonzalo Garcia-Atance; Smith, Edward H.; Sherrington, Ian

doi:10.1016/j.triboint.2013.10.001

Cited by 18 publications

(18 citation statements)

References 13 publications

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“…The signals recorded during the passage of each ring are substantially noise-free, and thus no averaging is necessary, a factor which has already been noted in an earlier paper. 9 The numbered labels in the first two strokes indicate the transducer from which the measurements were obtained. In this figure, the engine was operated at 3000 r/min, using the 15 W/40 lubricant.…”

Section: Resultsmentioning

confidence: 99%

“…Firstly, the piston can rotate about the piston pin; secondly, the ring can tilt in its groove, so that part of its circumference touches the top face of the groove with the remainder resting on the lower face; and thirdly, the forces on the ring can produce a twist about the cross-sectional axis. Taylor and Evans 7 have measured the first two effects, and Garcia-Atance Fatjo et al 9 have observed the overall result. If the ring shape is not uniform, then ring rotation can also have an influence.…”

Section: Introductionmentioning

confidence: 94%

“…In previous work, 9,13,14 the authors have measured film thicknesses in a range of engines with a capacitance technique. The technology employed limited most studies to relatively low piston velocities.…”

Section: Calibration and Measurement Accuracymentioning

confidence: 99%

“…This movement can produce squeeze-film effects that could have significant effects on the load-carrying capacity of the ring around top dead centre (TDC). 8 Evidence of ring lateral movement was obtained by Garcia-Atance Fatjo et al 9 The shape of the ring remains fixed, but the angle it subtends to the cylinder wall can change during operation. Firstly, the piston can rotate about the piston pin; secondly, the ring can tilt in its groove, so that part of its circumference touches the top face of the groove with the remainder resting on the lower face; and thirdly, the forces on the ring can produce a twist about the cross-sectional axis.…”

Section: Introductionmentioning

confidence: 96%

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Piston-ring film thickness: Theory and experiment compared

Fatjo

Smith

Sherrington

2017

Proceedings of the Institution of Mechanical Engineers, Part J:

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A review of the published literature has demonstrated a large variability and discrepancies in the measured and predicted values of piston-ring lubricating film thickness in internal combustion engines. Only 2 papers have been found that compare experiments in firing engines directly with outputs from sophisticated ring-pack lubrication models. The agreement between theory and experiment in these comparisons was limited, possibly because of inadequacies in the models and/ or inaccuracies of measurement. This paper seeks to contribute to the literature by comparing accurately calibrated experimental measurements of piston-ring film thickness in a firing engine with predictions from an advanced, commercial software package alongside details of the systematic analysis of the measurement errors in this process. Suggestions on how measurement accuracy could be further improved are also given. Measurements of oil film thickness with an error (standard deviation) of +/-15% have been achieved. It is shown that this error can be reduced further, by changes in the design and installation of the sensors.Detailed experimental measurements of film thickness under the top compression ring in a firing petrol engine have been made and compared with the predictions from a commercial, state-of-the art modelling package. The agreement between theory and experiment is excellent throughout the stroke in most cases, but some significant differences are observed at the lower load conditions. These differences are as yet unexplained, but may be due to the sensor topography influencing the hydrodynamic lubrication, lubricant availability, out-of-roundness in the cylinder, or squeeze effects. This a topic that requires further study.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Section: Calibration and Measurement Accuracymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Piston-ring film thickness: Theory and experiment compared

Fatjo

Smith

Sherrington

2017

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…During running-in, the wear process which occurs at the different small regions of the piston ring surface is different, as shown in Figure 2. Comparing with the size of the small region, the magnitude of ring twist is very small (Dunaevsky et al, 2000;Garcia-Atance Fatjo et al, 2014). Therefore, the ring twist is neglected in this research and the severest wear occurs near the Node 13 where the oil film thickness is minimum.…”

Section: Uneven Wear Model Of Rough Surfacementioning

confidence: 98%

On the running-in behavior of rough surface of piston rings in mixed lubrication regime

Cheng

Meng

Xie

et al. 2015

Industrial Lubrication and Tribology

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Purpose -The purpose of this paper is to study the real-time change of surface roughness at different small regions of piston rings during running-in process. Meanwhile, the effects of real-time change of the rough surface topography on the lubrication and friction of piston rings are investigated. Design/methodology/approach -An uneven wear model has been developed to research the running-in behavior at the different small regions of piston rings. The model is verified by comparing the simulation results with the experimental results on a reciprocating friction and wear test rig. Findings -This research shows that the wear process of piston ring surface is uneven during running-in. At most time of the operating cycle except the vicinity of top dead center and bottom dead center, the minimum oil film thickness ratio increases while the friction force and power loss decrease after the running-in period. Originality/value -Through this research, the running-in behavior of piston rings is investigated in detail. The interaction between the running-in and the lubrication and friction of piston rings is understood more deeply.

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Study on the moving cross‐hatched textures under starved lubrication based on parallel calculation

Meng

Zhang

et al. 2022

Lubrication Science

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The oil storage effect of textures is beneficial for lubrication performance under starved lubrication. When the larger of the two surfaces in friction pairs is textured, the moving textures should be considered because the boundary conditions are transiently changed at each moment. This is especially for the cross-hatched textures, which are manufactured on the cylinder liner while not on the piston ring. However, it means that the calculation cost will be very expensive for engineering friction pairs because the required calculation scale is very large and the required time step is very small. So the dynamic characteristics of moving textures on engineering surfaces are normally neglected in the existing researches. In this study, a starved lubrication model of the piston ring-cylinder liner (PRCL) system is established considering the oil storage effect, local hydrodynamic effect and dynamic characteristics of the moving cross-hatched textures. To speed up the calculation, an efficient parallel algorithm is developed. The results show that there is a significant difference in minimum oil film thickness (MOFT), wear load and oil film boundaries between stationary textures and moving textures, so the moving textures should not be simplified. This is helpful to find a better design of textures for engineering friction pairs.

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Mapping lubricating film thickness, film extent and ring twist for the compression-ring in a firing internal combustion engine

Cited by 18 publications

References 13 publications

Piston-ring film thickness: Theory and experiment compared

Piston-ring film thickness: Theory and experiment compared

On the running-in behavior of rough surface of piston rings in mixed lubrication regime

Study on the moving cross‐hatched textures under starved lubrication based on parallel calculation

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