Effects of Lubricant Viscosity and Surface Texturing on Ring-pack Performance in Internal Combustion Engines PDF Download
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Author: Rosalind Kazuko Takata
Publisher:
ISBN:
Category :
Languages : en
Pages : 134
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The piston ring-pack contributes approximately 25% of the mechanical losses in an internal combustion engine. Both lubricant viscosity and surface texturing were investigated in an effort to reduce this ring-pack friction and increase engine efficiency. While both optimizing viscosity and surface texturing are predicted to cause a reduction in ring/liner friction individually, a combined approach may cause an even greater friction reduction while mitigating unwanted side-effects such as oil consumption and wear. Existing MIT models, with some modifications and supplementary programs to allow investigation of the parameters of interest, were used to conduct this research. A ring-pack model based on average flow-factor Reynolds analysis was used for both studies, with a modified form of this program, along with a supplementary deterministic model for surface analysis, used for the study of surface texturing. Although these advanced models are applicable in a wide range of cases, the surface textures studied in this research are very different than a typical cylinder liner surface, and can be represented only approximately by the averaged Reynolds analysis upon which the ring simulation is based.
Author: Rosalind Kazuko Takata
Publisher:
ISBN:
Category :
Languages : en
Pages : 134
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Book Description
The piston ring-pack contributes approximately 25% of the mechanical losses in an internal combustion engine. Both lubricant viscosity and surface texturing were investigated in an effort to reduce this ring-pack friction and increase engine efficiency. While both optimizing viscosity and surface texturing are predicted to cause a reduction in ring/liner friction individually, a combined approach may cause an even greater friction reduction while mitigating unwanted side-effects such as oil consumption and wear. Existing MIT models, with some modifications and supplementary programs to allow investigation of the parameters of interest, were used to conduct this research. A ring-pack model based on average flow-factor Reynolds analysis was used for both studies, with a modified form of this program, along with a supplementary deterministic model for surface analysis, used for the study of surface texturing. Although these advanced models are applicable in a wide range of cases, the surface textures studied in this research are very different than a typical cylinder liner surface, and can be represented only approximately by the averaged Reynolds analysis upon which the ring simulation is based.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The piston ring-pack contributes approximately 25% of the mechanical losses in an internal combustion engine. Both lubricant viscosity and surface texturing were investigated in an effort to reduce this ring-pack friction and increase engine efficiency. While both optimizing viscosity and surface texturing are predicted to cause a reduction in ring/liner friction individually, a combined approach may cause an even greater friction reduction while mitigating unwanted side-effects such as oil consumption and wear. Existing MIT models, with some modifications and supplementary programs to allow investigation of the parameters of interest, were used to conduct this research. A ring-pack model based on average flow-factor Reynolds analysis was used for both studies, with a modified form of this program, along with a supplementary deterministic model for surface analysis, used for the study of surface texturing. Although these advanced models are applicable in a wide range of cases, the surface textures studied in this research are very different than a typical cylinder liner surface, and can be represented only approximately by the averaged Reynolds analysis upon which the ring simulation is based.
Author: Kai Liao (Ph. D.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 156
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The piston ring pack friction is a major contributor to the internal combustion engine mechanical friction loss. The oil control ring decides the oil supply to the top two rings in addition to being the major friction contributor in the ring pack. This work concentrated on the oil control ring friction. A large range of ring land widths and tensions, liner finish, and oil viscosity were investigated both experimentally and numerically to reveal how different factors affect the piston ring friction. A floating liner engine (FLE) was modified for motoring tests. The engine system repeatability and self-consistency were demonstrated. The thesis then discussed proper methods to select and measure the rings, liners and oil, which were important to generating meaningful results from the experiment. The ranges of engine speeds and liner temperatures were designed to ensure that all the lubrication modes, namely, boundary, mixed and hydrodynamic, can become dominant in both the instantaneous friction over a cycle and the FMEP over the engine speed range for any combination of rings, liners and lubricants. A parallel modeling effort was made to the experiments. The work showed that with careful preparation of adequate information on rings, liners and lubricants, the model can match the friction trends observed in the experiment over a large range of operating parameters and designs on the ring, liner finish and lubricant viscosity. The ring friction change over the liner break-in was studied using liners covering a wide range of surface roughness. The hydrodynamic pressure generation ability of the liner appears to be decided by the large surface structure. Therefore, the break-in process, which removes individual asperities from the plateau, does not affect pure hydrodynamic lubrication, and only the mixed lubrication is affected by the plateau roughness change. By keeping the same hydrodynamic pressure - ring/liner clearance (P-h) correlation and changing the plateau roughness, the model can predict the ring friction change over different lubrication regimes during the break-in. Compared to the current industry norm, a new engine power cylinder system design using a smaller land width twin land oil control ring with a lower ring tension and accompanied by a smoother liner surface gives lower friction and better oil control at the same time.
Author: Haijie Chen
Publisher:
ISBN:
Category :
Languages : en
Pages : 133
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Book Description
Piston ring packs are used in internal combustion engines to seal both the high pressure gas in the combustion chamber and the lubricant oil in the crank case. The interaction between the piston ring pack and the cylinder bore contributes substantially to the total friction power loss for IC engines. The aim of this thesis work is to advance the understanding of the ring liner lubrication through numerical modeling. A twin-land oil control ring lubrication model and a top two-ring lubrication model are developed based on a deterministic approach. The models take into consideration the effect of both the liner finish micro geometry and the ring face macro profile. The liner finish effect is evaluated on a 3D deterministically measured liner finish patch, with fully-flooded oil supply condition to the oil control rings and starved oil supply condition to the top two rings. Correlations based on deterministic calculations and proper scaling are developed to connect the average hydrodynamic pressure and friction to the critical geometrical parameters and operating parameters so that cycle evaluation of the ring lubrication can be performed in an efficient manner. The models can be used for ring pack friction prediction, and ring pack/liner design optimization based on the trade-off of friction power loss and oil consumption. To provide further insights to the effect of liner finish, a wear model is then developed to simulate the liner surface geometry evolution during the break-in/wear process. The model is based on the idea of simulated repetitive grinding on the plateau part of the liner finish using a random grinder. The model successfully captures the statistic topological features of the worn liner roughness. Combining the piston ring pack model and the liner finish wear model, one can potentially predict the long term ring pack friction loss. Finally the thesis covers the experimental validation of the twin-land oil control ring model using floating liner engine friction measurements. The modeled ring friction is compared with the experimental measurement under different ring designs and liner finishes. The result shows that the model in general successfully predicts the friction force of the twin-land oil control ring/liner pair.
Author: Boon-Keat Chui
Publisher:
ISBN:
Category : Internal combustion engines
Languages : en
Pages : 218
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Author: Jeffrey Alan Jocsak
Publisher:
ISBN:
Category :
Languages : en
Pages : 104
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(Cont.) The smaller angle decreased friction by blocking lubricant flow transport between the ring and liner thereby increasing the lubricant's effective viscosity and the effective lubricant film thickness between the ring and liner. Both of these effects enabled more ring load to be supported by hydrodynamic pressure, reducing ring-pack friction. There are potential adverse effects related to these surface finish modifications including an increase in the engine's susceptibility to scuffing, and an increase in oil consumption. Nonetheless, these modifications in surface finish reduce predicted ring-pack friction by approximately 1-10%.
Author: Camille Baelden
Publisher:
ISBN:
Category :
Languages : en
Pages : 218
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Book Description
Fuel consumption reduction of more than 20% can be achieved through engine friction reduction. Piston and piston rings contribute approximately half of the total engine friction and are therefore central to friction reduction efforts. The most common method to reduce mechanical losses from piston rings has been to lower ring tension, the normal force providing sealing between the piston ring and the cylinder liner. However tension reduction can result in additional lubricant consumption. The objective of this thesis is to understand and model the physical mechanisms resulting in flow of oil to the combustion chamber in order to achieve optimal designs of piston rings. The optimal design is a compromise between friction reduction and adequate gas and lubricant sealing performance. To do so a multi-scale curved beam finite element model of piston ring is developed. It is built to couple ring deformation, dynamics and contact with the piston and the cylinder. Oil flow at the interfaces between the ring and the cylinder liner and between the ring and the piston groove can thus be simulated. The piston ring model is used to study the sealing performance of the Oil Control Ring (OCR), whose function is to limit the amount of oil supplied to the ring pack. The contributions of the three main mechanisms previously identified, to oil flow past the OCR are quantified: - Deformation of the cylinder under operating conditions can lead to a loss of contact between the ring and the liner. - Tilting of the piston around its pin can force the OCR to twist and scrape oil from the liner. - Oil accumulating below the OCR can flow to the groove and leak on the top of the OCR The OCR is found to be flexible enough to limit the impact of cylinder deformation on oil consumption. Both ring scraping and flow through the OCR groove can contribute to oil consumption in the range of engine running conditions simulated. Reduction of scraping is possible by increasing the ability of both OCR lands to maintain contact with the liner regardless of piston groove tilt. The flow of oil through the OCR groove can be reduced by designing appropriate draining of oil in the groove and an adequate oil reservoir below the OCR. The piston ring oil transport model developed in this thesis will be a valuable tool to optimize ring pack designs to achieve further ring pack friction reduction without increasing oil consumption.
Author: Liang Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 143
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(Cont.) This model predicts the inter-ring gas pressure and 3-D displacements of the three rings at various circumferential locations. Model results show significant variations of the dynamic behavior along ring circumference. In the ring-pack lubrication model, an improved flow continuity algorithm is implemented in the ring/liner hydrodynamic lubrication, and proves to be very practicable. By coupling the ring/liner lubrication with the in-plane structural response of the ring, the lubrication along the entire ring circumference can be calculated. Model results show significant variations of lubrication along the circumference due to the non-axisymmetric characteristics of the power cylinder system. Bore distortion was found to have profound effects on oil transport along the liner. Particularly, it stimulates the occurrence of oil up-scraping by the top ring during compression stroke. Because the oil evaporation on the liner affects the liner oil film thickness, a sub-model for liner evaporation with consideration of multi-species oil is incorporated with the lubrication model. With consideration of oil transport along the liner, the prediction of evaporation is more precise. The combination of these models is a complete package for piston ring-pack analysis. It is computationally robust and efficient, and thus has appreciable practical value.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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By Tian Tian.
Author: Mikhail Aleksandrovich Ejakov
Publisher:
ISBN:
Category : Internal combustion engines
Languages : en
Pages : 386
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