A Study of the Friction (piston-liner Interaction) in Internal Combustion Engines Using a Floating Liner Engine PDF Download
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Author: Sarthak Vaish
Publisher:
ISBN:
Category :
Languages : en
Pages : 91
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Book Description
With the increasing interest in decreasing the environmental impact from internal combustion engines as well as increasing the fuel efficiency has led to deeper investigation into the components of the engine. The mechanical friction in an engine is a major concern, any improvements or reductions in friction can have large implication on the' efficiency of the engines. This thesis focuses on the piston/ ring pack assembly and its contribution to friction. It investigates several key components and trends in friction for the piston/ ring pack assembly, specifically the trends related to the oil control ring and the liner surface. The Floating Liner Engine is used in this study to isolate results from different components. The data collected can be used for comparative analysis and to identify trends in the friction trace. The thesis starts with describing the Floating Liner Engine system at MIT in detail. Both the data collection and the hardware systems are described as well as the test capabilities of the Floating Liner Engine. The results used in the thesis have been collected using the motoring condition. The oil control ring plays a key role in controlling the supply of oil to the top two rings and hence has a higher tension that the top two rings. This leads to the oil control ring having a significant contribution to the total friction of the system. The two most prevalent oil control rings used in the industry are the twin land oil control ring (TLOCR) and the three piece oil control ring (TPOCR). The thesis investigates the effect of changing liner roughness on the friction of the TLOCR. A comparison between the TLOCR and the TPOCR is also performed using the same liner surfaces. The results from these studies show a marked difference between the friction traces from the two oil control rings.
Author: Sarthak Vaish
Publisher:
ISBN:
Category :
Languages : en
Pages : 91
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Book Description
With the increasing interest in decreasing the environmental impact from internal combustion engines as well as increasing the fuel efficiency has led to deeper investigation into the components of the engine. The mechanical friction in an engine is a major concern, any improvements or reductions in friction can have large implication on the' efficiency of the engines. This thesis focuses on the piston/ ring pack assembly and its contribution to friction. It investigates several key components and trends in friction for the piston/ ring pack assembly, specifically the trends related to the oil control ring and the liner surface. The Floating Liner Engine is used in this study to isolate results from different components. The data collected can be used for comparative analysis and to identify trends in the friction trace. The thesis starts with describing the Floating Liner Engine system at MIT in detail. Both the data collection and the hardware systems are described as well as the test capabilities of the Floating Liner Engine. The results used in the thesis have been collected using the motoring condition. The oil control ring plays a key role in controlling the supply of oil to the top two rings and hence has a higher tension that the top two rings. This leads to the oil control ring having a significant contribution to the total friction of the system. The two most prevalent oil control rings used in the industry are the twin land oil control ring (TLOCR) and the three piece oil control ring (TPOCR). The thesis investigates the effect of changing liner roughness on the friction of the TLOCR. A comparison between the TLOCR and the TPOCR is also performed using the same liner surfaces. The results from these studies show a marked difference between the friction traces from the two oil control rings.
Author: Zach Westerfield
Publisher:
ISBN:
Category :
Languages : en
Pages : 120
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Book Description
The recent worldwide quest to increase the fuel efficiency of internal combustion engines has led to great effects to reduce friction of many of the components in these engines. One area of major concern pertaining to this area is the friction of the piston/ring pack assembly. Because of the importance and necessity of this component to the internal combustion engine, any improvements can have relatively large implications for friction reduction. The purpose of this paper is to investigate several key components of the piston/ring pack assembly and how they influence friction levels. Specifically, experimental friction trends related to the oil control ring, piston skirt, liner surface and lubricant will be discussed. The Floating Liner Engine is used in this study in both the motored and fired configuration to isolate results from components and provide data for comparative analysis. The oil control ring (OCR) controls the supply of lubricating oil to the top two rings of the ring pack and has a significant contribution to friction of the system. This study investigates the two most prevalent types of OCR in the automotive market: the twin land oil control ring (TLOCR) and three piece oil control ring (TPOCR). The effect of changing the land width and spring tension on different liner surfaces for the TLOCR is investigated, and distinct trends are identified. A comparison is then done between the TLOCR and TPOCR on different liner surfaces. Results showed the TPOCR displayed different patterns of friction compared the TLOCR in certain cases. The piston skirt is also an important contributor of friction in the piston assembly. This thesis discusses the investigation into low friction coatings on the piston skirt. A brief study of piston skirt patterns is presented, with little gains being made by applying patterns the piston skirt coating. Next the roughness of the piston skirt coating is analyzed, and results show that reducing piston skirt roughness can have positive effects on friction reduction. Finally, an introductory study into the profile of the piston skirt is presented, with the outcome being that friction reduction is possible by optimizing the skirt profile. The final section of this thesis discusses the effects of lubricants pertaining to friction in the piston assembly. The effects of changing lubricant viscosity through both temperature and formulation are presented, as well as results from testing the effects of select anti-wear additives in the oil. The results identify new developments related to lubricant/additive effects on the liner surface, and how these effects can influence friction.
Author: Qing Zhao (S.M.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 88
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Book Description
When decreasing of fossil fuel supplies and air pollution are two major society problems in the 21st century, rapid growth of internal combustion (IC) engines serves as a main producer of these two problems. In order to increase fuel efficiency, mechanical loss should be controlled in internal combustion engines. Interaction between piston ring pack and cylinder liner finish accounts for nearly 20 percent of the mechanical losses within an internal combustion engine, and is an important factor that affects the lubricant oil consumption. Among the total friction between piston ring pack and cylinder liner, boundary friction occurs when piston is at low speed and there is direct contact between rings and liners. This work focuses on prediction of contact between piston ring and liner finish based on 3D measured surface and different methods are compared. In previous twin-land oil control ring (TLOCR) deterministic model, Greenwood-Tripp correlation function was used to determine contact. The practical challenge for this single equation is that real plateau roughness makes it unreliable. As a result, micro geometry of liner surface needs to be obtained through white light interferometry device or confocal equipment to conduct contact model. Based on real geometry of liner finish and the assumption that ring surface is ideally smooth, contact can be predicted by three different models which were developed by using statistical Greenwood-Williamson model, Hertzian contact and revised deterministic dry contact model by Professor A.A. Lubrecht. The predicted contact between liner finish and piston ring is then combined with hydrodynamic pressure caused by lubricant which was examined using TLOCR deterministic model by Chen. et al to get total friction resulted on the surface of liner finish. Finally, contact model is used to examine friction of different liners in an actual engine running cycle.
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: Allan T. Kirkpatrick
Publisher: John Wiley & Sons
ISBN: 1119454530
Category : Science
Languages : en
Pages : 656
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Book Description
A comprehensive resource covering the foundational thermal-fluid sciences and engineering analysis techniques used to design and develop internal combustion engines Internal Combustion Engines: Applied Thermosciences, Fourth Edition combines foundational thermal-fluid sciences with engineering analysis techniques for modeling and predicting the performance of internal combustion engines. This new 4th edition includes brand new material on: New engine technologies and concepts Effects of engine speed on performance and emissions Fluid mechanics of intake and exhaust flow in engines Turbocharger and supercharger performance analysis Chemical kinetic modeling, reaction mechanisms, and emissions Advanced combustion processes including low temperature combustion Piston, ring and journal bearing friction analysis The 4th Edition expands on the combined analytical and numerical approaches used successfully in previous editions. Students and engineers are provided with several new tools for applying the fundamental principles of thermodynamics, fluid mechanics, and heat transfer to internal combustion engines. Each chapter includes MATLAB programs and examples showing how to perform detailed engineering computations. The chapters also have an increased number of homework problems with which the reader can gauge their progress and retention. All the software is ‘open source’ so that readers can see in detail how computational analysis and the design of engines is performed. A companion website is also provided, offering access to the MATLAB computer programs.
Author: Tianshi Fang
Publisher:
ISBN:
Category :
Languages : en
Pages : 136
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Book Description
The consumption of lubricating oil in internal combustion engines is a continuous interest for engine developers and remains to be one of the least understood areas. A better understanding on oil transport is critical to an optimization of engine designs, and advanced analytical tools are essential to the achievement of reduced frictions without compromising oil consumption. Oil transport from piston lands to a liner, hereafter called "bridging", has been observed in engine tests. The additional oil transferred to the liner becomes a potential source of oil consumption through ring-liner interaction. Thus, it is important to develop more quantitative models to better analyze bridging. The objective of this work is to obtain a more in-depth understanding on the oil transport between piston lands and liner and provide quantitative models of the oil transport mechanisms. Multiphase Computational Fluid Dynamics (CFD) was employed together with analyses of experimental observations. Three categories of bridging were identified: assisted bridging, self-sustained bridging, and reverse bridging. While assisted bridging involves an axial oil flow across an entire piston land, the other two phenomena are localized and become prominent at low engine speeds. The mechanisms of each phenomenon were analyzed in this work. Correlations and theoretical models were developed to associate the risk of bridging with geometrical designs of a piston and operating conditions of an engine. Particularly, the theoretical model of self-sustained bridging contributes to the optimization of geometrical designs of the third land of a piston ring pack. This work constitutes a major step towards a further quantification of oil transport. Some findings and models presented in this work can readily contribute to providing optimal solutions to certain piston regions. Furthermore, the results of this work serve broader purposes in providing boundary conditions to other interactions in a piston ring pack.
Author: Homer Rahnejat
Publisher: Elsevier
ISBN: 1845699939
Category : Technology & Engineering
Languages : en
Pages : 1059
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Book Description
Tribology, the science of friction, wear and lubrication, is one of the cornerstones of engineering’s quest for efficiency and conservation of resources. Tribology and dynamics of engine and powertrain: fundamentals, applications and future trends provides an authoritative and comprehensive overview of the disciplines of dynamics and tribology using a multi-physics and multi-scale approach to improve automotive engine and powertrain technology.Part one reviews the fundamental aspects of the physics of motion, particularly the multi-body approach to multi-physics, multi-scale problem solving in tribology. Fundamental issues in tribology are then described in detail,from surface phenomena in thin-film tribology, to impact dynamics, fluid film and elastohydrodynamic lubrication means of measurement and evaluation. These chapters provide an understanding of the theoretical foundation for Part II which includes many aspects of the physics of motion at a multitude of interaction scales from large displacement dynamics to noise and vibration tribology, all of which affect engines and powertrains. Many chapters are contributed by well-established practitioners disseminating their valuable knowledge and expertise on specific engine and powertrain sub-systems. These include overviews of engine and powertrain issues, engine bearings, piston systems, valve trains, transmission and many aspects of drivetrain systems. The final part of the book considers the emerging areas of microengines and gears as well as nano-scale surface engineering.With its distinguished editor and international team of academic and industry contributors, Tribology and dynamics of engine and powertrain is a standard work for automotive engineers and all those researching NVH and tribological issues in engineering. Reviews fundamental aspects of physics in motion, specifically the multi-body approach to multi physics Describes essential issues in tribology from surface phenomena in thin film tribology to impact dynamics Examines specific engine and powertrain sub-systems including engine bearings, piston systems and value trains
Author: Jérôme Sacherer
Publisher:
ISBN:
Category :
Languages : en
Pages : 72
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Book Description
Automotive manufacturers are increasingly replacing traditional cast iron liners in the internal combustion engines of commercial vehicles with spray-coated liners. While not the original intention, these new, porous liners are suspected to reduce hydrodynamic friction. The interaction of pores with piston ring and liner lubrication is studied in this work. Preliminary computational fluid dynamics simulations are performed on a single, idealized pore geometry, including surface tension but no cavitation due to computational cost limitations. Potential mechanisms for displacement of oil out of the pore are investigated, as this would improve subsequent ring lubrication. Pressure-driven flow is found to dominate this process, though surface tension also has an impact: it can trap air bubbles in the pore and level out accumulated oil back into the evacuated pore. A deterministic model exists to predict hydrodynamic pressure and friction for rough and honed liner surfaces. This model, however, assumes fully flooded boundary conditions. A modification to the governing equation for the regions beyond the full film boundaries is developed by introducing a diffusive velocity profile. The diffusion provides a transition between an oil film on the liner experiencing uniform flow to full film Couette flow. This change enables the large pore geometry to be accommodated by the model without unrealistic premature film attachment all the while maintaining the continuous transition between full film and cavitation. Results from the model indicate that the pore can act as an oil supply, extending the wetting region beneath the ring and consequently allowing for greater pressure generation and larger, desirable load carrying capacity. Cavitation also plays a critical role in the pore interaction; early cavitation in the pore can split the full film region, significantly compromising the load carrying capacity. Cavitation is also found to potentially make use of the pore's oil supply to redistribute oil onto the liner. In general, the pore causes a substantial drop in lift force, increasing the coefficient of friction as a result, though in some cases an extended wetting region can counter this effect.
Author: Md Rezaul Islam
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Chongjie Gu
Publisher:
ISBN:
Category :
Languages : en
Pages : 108
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Book Description
Internal combustion engines are widely utilized in modem automobiles. Around 10% of the total fuel energy is dissipated to heat due to mechanical friction, among which 20% is caused by the contact between the cylinder liner and the piston rings. The wear of cylinder liner not only leads to surface damage, but also results in the change of liner lubrication conditions. Therefore, a large number of tests are performed by researchers to investigate the liner wear process and its impact on engine lubrication. This work is the first step toward developing a wear model to predict the evolution of liner roughness and ring pack lubrication during break-in period. A physics-based liner wear model is built in this work, with focus on two mechanisms: surface plastic flattening and fatigue wear. Both mechanisms are simulated through a set of governing equations and are coupled together to complete the algorithm of the liner wear model. Simulations of break-in wear are performed to different liner surfaces finishes, with different external normal pressures. Simulation results indicate that the liner wear rate depends on the size and shape of liner surface asperities, which may provide guidance for surface manufacturing. The results also show consistence with the Archard's wear law, describing the proportional correlation between normal pressure and steady state wear rate. This wear model is then used to study the influence of liner wear on engine lubrication. Through the friction for entire engine cycles, simulated results are compared with experimental friction measurements. The comparison shows that the calculated friction evolution during break-in has the same trend and comparable magnitude as the measurements, indicating the efficiency of the wear model. Some initial work of modeling of third-body abrasive wear is also discussed in this thesis.
