Download or read book Modeling the Effects of Piston Skirt Distortion on the Design of Pistons for Optimum Lubrication in a Reciprocating Engine written by William Lawrence Blair and published by . This book was released on 1989 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Role of Piston Distortion on Lubrication in a Reciprocating Engine written by William L. Blair and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Piston Design and Lubricant Selection on Reciprocating Engine Friction written by Luke Frank Moughon and published by . This book was released on 2006 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) Moreover, increasing oil supply (i.e., increasing effective oil film thickness) tends to decrease net friction by promoting hydrodynamic lubrication. Changes to piston geometry were shown to have significant effects on friction. In order to maximize hydrodynamic support, the pressure must be distributed evenly across the piston skirt; this can be achieved by making the skirt-liner clearance as even and smooth as possible. The model confirmed that skirt profiles with gentle slopes tend to reduce net friction, as do skirt ovality values that closely approximate the shape of the liner. Moreover, the grooves machined into the skirt surface were shown to have a deleterious effect on friction if their amplitude was large relative to the thickness of the oil film. Using relatively small-amplitude grooves facilitates oil movement and retention without leading to direct contact with the liner. After piston geometry has been optimized to promote hydrodynamic lubrication, further refinements, such as reducing oil viscosity, are possible.
Download or read book ASME Technical Papers written by and published by . This book was released on with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling Piston Skirt Lubrication in Internal Combustion Engines written by Dongfang Bai (Ph. D.) and published by . This book was released on 2012 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ever-increasing demand for reduction of the undesirable emissions from the internal combustion engines propels broader effort in auto industry to design more fuel efficient engines. One of the major focuses is the reduction of engine mechanical losses, to which the friction of the piston skirt is one important contributor. Yet there lacks a sufficient understanding of the skirt lubrication behavior to effectively optimize the piston skirt system in practice. The ultimate goal of this work is to develop a comprehensive model to advance the predictability of the skirt friction while integrating all the dynamic behavior of the piston secondary motion and the structural deformation of the piston skirt and cylinder liner. Major contributions of this work are analysis of and development of a model for the oil transport and exchange of the piston skirt region and its surroundings. The new oil transport model is composed with two elements. First, the oil scraped into the chamfer region by the oil control ring during a down-stroke is tracked and its accumulation and release to the skirt region are modeled. Second, oil separation and re-attachment are allowed in the skirt region, breaking conventional full-attachment assumption in lubrication studies. The new oil transport model together with hydrodynamic and boundary lubrication model were coupled with piston secondary motion and structural deformation of the piston skirt and cylinder liner. For numerical efficiency and physics clarity, we used different discretization for the lubrication from the structural deformation. The final model is robust and efficient. The discussion of the model results is focused mainly on the oil transport. There exist a general pattern in available oil for skirt lubrication, namely, skirt tends to be starved when it travels at the upper portion of a stroke. Comparison with visualization experiment for oil accumulation patterns show consistency between model prediction and observation. This work represents a major step forward to realistically predicting skirt friction and the influence of all the relevant design and operational parameters. However, oil supply to the region below the piston skirt can largely influence the outcome of the friction prediction and its mechanism is system dependent. Additionally, simple treatment of the oil transport in the current model is merely a first step to modeling the complex fluid problems involved. Improvements of this model based on application and further analysis will make it a more powerful engineering tool to optimize the skirt system to minimize its undesirable outputs.
Download or read book Modeling Piston Secondary Motion and Skirt Lubrication with Applications written by Pasquale Pio Totaro and published by . This book was released on 2014 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: The interest in reducing emission and improving engine efficiency has become a major push in industry, due to upcoming stricter regulations. A great deal of attention has been given to the frictional losses due to piston and liner interaction, as they represent a significant portion of the total mechanical losses. This thesis work focuses on further development and application of an existing model for the piston's secondary motion and skirt lubrication. Model development has been focused on introducing liner dynamic deformation, temperature and shear-thinning effect on viscosity, and arbitrary skirt's shape definition. The theory behind the inclusion of these components is discussed and the modifications to the existing model are explained. In regards to the model's applications, an important topic is the model validation, for which friction results from simulations are compared with experimental results obtained on a floating liner engine. The analysis covers the running condition of 1000 rpm, at partial and full load. This study is, however, not concluded and more cases need to be studied in order to complete the validation of the model. The second application focuses on the effects of geometrical patterns on the skirt on friction and secondary motion of the piston. First, some regular patterns were studied and found to have negative effects on friction due to their inability to build sufficient hydrodynamic pressure, compared to the baseline design. Then, a different sets of patterns were proposed to more effectively utilize available oil and to maximize the hydrodynamic pressure generation in the skirt region. The results show that new strategy can significantly reduce friction of the skirt without introducing negative impact on the secondary motion. This thesis work aims to make the model a more complete and powerful tool to understand piston's secondary motion and the applications are meant to show the capabilities of the model, as an instrument to approach piston's design and inspire new ways and ideas to reduce frictional losses.
Download or read book Numerical Modeling of Piston Secondary Motion and Skirt Lubrication in Internal Combustion Engines written by Fiona McClure and published by . This book was released on 2007 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: Internal combustion engines dominate transportation of people and goods, contributing significantly to air pollution, and requiring large amounts of fossil fuels. With increasing public concern about the environment and the reliability of oil supplies, automotive companies are pushed to improve engine design in order to reduce engine emissions and fuel consumption. This project aims to develop a numerical model of piston dynamics and lubrication in internal combustion engines, enabling prediction of friction generation at the piston -cylinder bore interface, and oil transport in the power cylinder system. It is currently estimated that the piston - cylinder bore friction accounts for up to 25% of the power loss in a typical engine, while oil transported to the combustion chamber by the piston and ring-pack contributes significantly to engine emissions. A dry piston model was first developed to allow fast calculation of approximate piston dynamics. An elastohydrodynamic lubrication model was then developed to allow direct numerical simulation of the effect of piston tooling marks, and comparison with results obtained using an Average Reynolds equation with flow factors. The lubrication model was incorporated into the piston dynamics model, enabling more accurate evaluation of friction and oil transport. Comparison between the dry and lubricated model results demonstrate the effect of oil film thickness on piston lateral motion, tilt, friction generation and oil transport.
Download or read book Analysis of Surface Roughness on Piston Skirt Lubrication written by Mubashir Gulzar and published by LAP Lambert Academic Publishing. This book was released on 2012 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book focuses the rough piston skirts and liner surfaces and to incorporate these aspects in two dimensional hydrodynamic and elastohydrodynamic lubrication (EHL) of piston skirts in the initial engine start-up. This research work considers the deterministic roughness asperity with the average flow factor method.The randomly generated surface with deterministic asperity is modelled for piston skirt EHL. For this developed model, parametric studies on the salient features like the engine start-up speed, hydrodynamic load, radial clearance, and viscosity of lubricant, is undertaken.
Download or read book Predictive Modeling of Piston Assembly Lubrication in Reciprocating Internal Combustion Engines written by Huijie Xu and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Piston Design and Analysis written by Andreas Petrou Panayi and published by . This book was released on 2006 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling the Effects of Liner Pores on Piston Ring Lubrication in Internal Combustion Engines written by Jérôme Sacherer and published by . This book was released on 2019 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Low Engine Friction Technology for Advanced Natural Gas Reciprocating Engines written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston and piston ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and wear. An iterative process of simulation, experimentation and analysis has been followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. In this program, a detailed set of piston and piston-ring dynamic and friction models have been adapted and applied that illustrate the fundamental relationships among mechanical, surface/material and lubricant design parameters and friction losses. Demonstration of low-friction ring-pack designs in the Waukesha VGF 18GL engine confirmed ring-pack friction reduction of 30-40%, which translates to total engine FEMP (friction mean effective pressure) reduction of 7-10% from the baseline configuration without significantly increasing oil consumption or blow-by flow. The study on surface textures, including roughness characteristics, cross hatch patterns, dimples and grooves have shown that even relatively small-scale changes can have a large effect on ring/liner friction, in some cases reducing FMEP by as much as 30% from a smooth surface case. The measured FMEP reductions were in good agreement with the model predictions. The combined analysis of lubricant and surface design indicates that low-viscosity lubricants can be very effective in reducing friction, subject to component wear for extremely thin oils, which can be mitigated with further lubricant formulation and/or engineered surfaces. Hence a combined approach of lubricant design and appropriate wear reduction offers improved potential for minimum engine friction loss. Testing of low-friction lubricants showed that total engine FMEP reduced by up to (almost equal to)16.5% from the commercial reference oil without significantly increasing oil consumption or blow-by flow. Piston friction studies indicate that a flatter piston with a more flexible skirt, together with optimizing the waviness and film thickness on the piston skirt offer significant friction reduction. Combined with low-friction ring-pack, material and lubricant parameters, a total power cylinder friction reduction of 30-50% is expected, translating to an engine efficiency increase of two percentage points from its current baseline towards the goal of 50% ARES engine efficiency. The design strategies developed in this study have promising potential for application in all modern reciprocating engines as they represent simple, low-cost methods to extract significant fuel savings. The current program has possible spinoffs and applications in other industries as well, including transportation, CHP, and diesel power generation. The progress made in this program has wide engine efficiency implications, and potential deployment of low-friction engine components or lubricants in the near term is quite possible.
Download or read book Introduction to Modeling and Simulation of Piston Ring Lubrication written by Ali Usman and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book include elementary study of Piston-Ring lubrication in Hydrodynamics (HL) and Elasto-Hydrodynamic (EHL) domain at low load-low speed operating conditions. Effects of Piston-Ring running face profile, Engine speed and Elliptically distorted bore are investigated. Vogelpohl parameter technique along with Finite Difference Method is used to solve steady state Reynolds equation for Compression ring of a gasoline engine. Performance parameters (Oil Film thickness in HL and EHL, Friction Force, Power Loss and Flow-rate of lubricating oil) are shown graphically and explained.
Download or read book Effects of Non Newtonian Lubricant Rheology on Elastohydrodynamic Lubrication of Piston Skirts in Engine Initial Start Up Condition written by Usman Chaudhri and published by . This book was released on 2014 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Lubrication of the Piston Skirt written by Milton C. Shaw and published by . This book was released on 1945 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Automotive Engine Piston written by Walter Trefz and published by . This book was released on 1943 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Multi scale Model for Piston Ring Dynamics Lubrication and Oil Transport in Internal Combustion Engines written by Camille Baelden and published by . This book was released on 2014 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
