Prediction of ring-bore conformance and contact condition and experimental validation

One of the key conjunctions in the IC engine is that made by the top compression ring to the cylinder liner. Although the compression ring has seen considerable improvements since its introduction into steam engines by John Ramsbottom in the 1850s, its multiple and often contradictory functions stil...

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Main Authors: Michael Theaker, Ramin Rahmani, Homer Rahnejat
Format: Default Conference proceeding
Published: 2012
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Online Access:https://hdl.handle.net/2134/13971
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spelling rr-article-95458552012-01-01T00:00:00Z Prediction of ring-bore conformance and contact condition and experimental validation Michael Theaker (4885057) Ramin Rahmani (1250418) Homer Rahnejat (1247550) Mechanical engineering not elsewhere classified untagged Mechanical Engineering not elsewhere classified One of the key conjunctions in the IC engine is that made by the top compression ring to the cylinder liner. Although the compression ring has seen considerable improvements since its introduction into steam engines by John Ramsbottom in the 1850s, its multiple and often contradictory functions still remain a challenge today. The primary aim has always been to seal the combustion chamber and guard against leakage of combustion gasses. The ring is also required to conduct some of the generated heat away. These requirements call for good ring-bore conformance, but often at the expense of increased friction. A simplified inter-ring gas flow model, as well as the measured chamber pressure using a Kistler pressure transducer is carried out under motored conditions to obtain the net gas pressure acting behind the ring. This and the elastic pressure as the result of ring restoring tension force in fitment constitute the contact load, which is usually carried by a mixed-hydrodynamic regime of lubrication. The conjunction pressures are treated as a combination of hydrodynamic generated pressures and asperity-pair interactions. The former is obtained by solution of two dimensional Reynolds equation, whilst the latter is determined assuming a Gaussian distribution of asperities on the counterfaces. Surface topography of the bounding solids; the compression ring and the liner are measured and used as appropriate statistical functions in the Greenwood and Tripp model. Using an analytical flow model, pressure acting behind the ring (on the inner periphery of the ring) is obtained, leading to the calculation of ring-bore friction. A floating liner is used to measure friction of piston and ringpack in situ. The characteristic of the predicted variations are compared with the measured data. However, a quantitative comparison is not possible as the measured data corresponds to all the conjunctions of piston system, including the oil control rings as well as the piston skirt. The results show that variation of gas force behind the ring significantly changes the ring-bore contact, thus friction and the nature of interactions. 2012-01-01T00:00:00Z Text Conference contribution 2134/13971 https://figshare.com/articles/conference_contribution/Prediction_of_ring-bore_conformance_and_contact_condition_and_experimental_validation/9545855 CC BY-NC-ND 4.0
institution Loughborough University
collection Figshare
topic Mechanical engineering not elsewhere classified
untagged
Mechanical Engineering not elsewhere classified
spellingShingle Mechanical engineering not elsewhere classified
untagged
Mechanical Engineering not elsewhere classified
Michael Theaker
Ramin Rahmani
Homer Rahnejat
Prediction of ring-bore conformance and contact condition and experimental validation
description One of the key conjunctions in the IC engine is that made by the top compression ring to the cylinder liner. Although the compression ring has seen considerable improvements since its introduction into steam engines by John Ramsbottom in the 1850s, its multiple and often contradictory functions still remain a challenge today. The primary aim has always been to seal the combustion chamber and guard against leakage of combustion gasses. The ring is also required to conduct some of the generated heat away. These requirements call for good ring-bore conformance, but often at the expense of increased friction. A simplified inter-ring gas flow model, as well as the measured chamber pressure using a Kistler pressure transducer is carried out under motored conditions to obtain the net gas pressure acting behind the ring. This and the elastic pressure as the result of ring restoring tension force in fitment constitute the contact load, which is usually carried by a mixed-hydrodynamic regime of lubrication. The conjunction pressures are treated as a combination of hydrodynamic generated pressures and asperity-pair interactions. The former is obtained by solution of two dimensional Reynolds equation, whilst the latter is determined assuming a Gaussian distribution of asperities on the counterfaces. Surface topography of the bounding solids; the compression ring and the liner are measured and used as appropriate statistical functions in the Greenwood and Tripp model. Using an analytical flow model, pressure acting behind the ring (on the inner periphery of the ring) is obtained, leading to the calculation of ring-bore friction. A floating liner is used to measure friction of piston and ringpack in situ. The characteristic of the predicted variations are compared with the measured data. However, a quantitative comparison is not possible as the measured data corresponds to all the conjunctions of piston system, including the oil control rings as well as the piston skirt. The results show that variation of gas force behind the ring significantly changes the ring-bore contact, thus friction and the nature of interactions.
format Default
Conference proceeding
author Michael Theaker
Ramin Rahmani
Homer Rahnejat
author_facet Michael Theaker
Ramin Rahmani
Homer Rahnejat
author_sort Michael Theaker (4885057)
title Prediction of ring-bore conformance and contact condition and experimental validation
title_short Prediction of ring-bore conformance and contact condition and experimental validation
title_full Prediction of ring-bore conformance and contact condition and experimental validation
title_fullStr Prediction of ring-bore conformance and contact condition and experimental validation
title_full_unstemmed Prediction of ring-bore conformance and contact condition and experimental validation
title_sort prediction of ring-bore conformance and contact condition and experimental validation
publishDate 2012
url https://hdl.handle.net/2134/13971
_version_ 1756513029561778176