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Piston Ring Conformability in a Distorted Bore
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English
Abstract
Some different equations to calculate the maximum deformation that a given ring can conform to, are found in the bibliography. These equations do not consider the ring end gap and ovality, gas pressure acting on it, nor the actual bore shape, but only the maximum amplitude for a given term (from a Fourier Series that describes the bore shape). A more exact prediction can be done with Finite Element tools or specific codes for piston ring simulation; those approaches are not usually carried out, except in special cases or in more fundamental studies.
Experimental measurements were carried out to verify the simple conformability criteria. Deformed shapes were produced in a static jig and areas of “non contact”, between ring and the deformed bore shapes, were measured.
Based on these measurements, a semi-empirical equation is proposed to calculate the limit of piston ring conformability. The proposed equation is simple enough to be calculated in the initial engine design phases (where the required inputs to more detailed methods are not available) or on a “day-by-day” basis.
If bore deformation surpasses the ring conformability, the percentage of ring periphery contacting the bore can be estimated, in a first approximation, by the linear regression empirically found in the experiments.
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Authors
Citation
Tomanik, E., "Piston Ring Conformability in a Distorted Bore," SAE Technical Paper 960356, 1996, https://doi.org/10.4271/960356.Also In
References
- Abe, S. Suzuki, M. “Analysis of Cylinder Bore Distortion During Engine Operation” SAE paper 950541 1995
- Brombolich, L. “Effect of Cylinder Distortions and Piston Ring Design on Oil Consumption and Friction Losses in Automobile Engines” DOE Report No. ANL/TPRR/89/1 1989
- English, C. “Kolbenringe - Band I” Wien Springer-Verlag 1958
- Koch, F. “A New Technique for Measuring the Deformation of Cylinder Bores During Engine Operation” SAE paper 950540 1995
- Muller, R. “Zur Frage des Formfullungsvermogens von Kolbenringen in von der Kreisform abweichenden Bohrungen gleicher Umfanglange” MTZ 31 79 82 1970
- Dunaevsky, V.V. “Analysis of Distortions of Cylinders and Conformability of Piston Rings” Tribology Transactions 33 33 40 1990
- Mierbach, A. “Berechning der Radialdruckverteilung von Kolbenringen in verzogenen Zylinderbuchsen” GOETZE publication
- Heywood, J. B. “Internal Combustion Engine Fundamentals” 360 365 McGraw-Hill international Editions 1988
- Keribar, R. et al “An Integrated Predictive Design Analysis Methodology to Address Piston Tribological Issues” SAE paper 930793 1993