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A Multi-scale Model for Piston Ring Dynamics, Lubrication and Oil Transport in Internal Combustion Engines

2014
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Release : 2014
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Book Synopsis A Multi-scale Model for Piston Ring Dynamics, Lubrication and Oil Transport in Internal Combustion Engines by : Camille Baelden

Download or read book A Multi-scale Model for Piston Ring Dynamics, Lubrication and Oil Transport in Internal Combustion Engines written by Camille Baelden. This book was released on 2014. 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.

A Multi-scale Model Integrating Both Global Ring Pack Behavior and Local Oil Transport in Internal Combustion Engines

2017
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Release : 2017
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Book Synopsis A Multi-scale Model Integrating Both Global Ring Pack Behavior and Local Oil Transport in Internal Combustion Engines by : Yang Liu (Ph. D.)

Download or read book A Multi-scale Model Integrating Both Global Ring Pack Behavior and Local Oil Transport in Internal Combustion Engines written by Yang Liu (Ph. D.). This book was released on 2017. Available in PDF, EPUB and Kindle. Book excerpt: Improving fuel economy of internal combustion engines is one of the major focuses in automotive industry. The piston ring friction contributes as much as 25% of total mechanical loss in internal combustion engines [1] and is an area of great interests to the automotive industry in their overall effort to improve engine efficiency. However, typical methods to reduce friction loss from piston ring pack, such as ring tension reduction, may cause additional oil consumption. A compromise between reduction of friction loss and control of gas leakage and oil consumption needs to be made, which requires a deep understanding of oil transport mechanism. This compromise gives rise to the interest in modeling work. Both experimental results and previous experience showed that oil film distribution on the piston varies significantly along the circumference and the oil leakage occurs locally. Therefore to predict oil transfer across different ring pack regions, one needs to integrate both global and local processes. This work is aimed at establishing an enduring framework for all the cycle-based processes at different length scales. As a first step, a multi-scale multi-physics piston ring pack model was developed by coupling the structural dynamics of the piston rings with gas flows and local interactions at ring-groove and ring-liner interfaces. A curved beam finite element method was adopted to calculate the ring structural response to interaction between the ring and the liner as well as the ring and the groove. Compared to a traditional straight beam finite element method, the curved beam separates the structural mesh and contact grid by utilizing the shape functions. In this work, a multi-length-scale ring pack model was, for the first time, successfully assembled. This model bears its fundamental values to truly reflect the integral results of all the relevant mechanisms. The significance of the current work is that it demonstrated such an integration of all the length scales is possible for a cycle model with a reasonable computation cost. With the current model, one can realistically investigate the effects of all kinds of piston and liner distortion, piston secondary motion, bridging, and lube-oil dilution on gas sealing, oil transport and lubrication. As a result, optimization of the ring designs and the part of block design contributing to bore distortion can be coordinated to reduce development costs.

Modeling Engine Oil Vaporization and Transport of the Oil Vapor in the Piston Ring Pack on Internal Combustion Engines

2004
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Release : 2004
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Book Synopsis Modeling Engine Oil Vaporization and Transport of the Oil Vapor in the Piston Ring Pack on Internal Combustion Engines by : Yeunwoo Cho

Download or read book Modeling Engine Oil Vaporization and Transport of the Oil Vapor in the Piston Ring Pack on Internal Combustion Engines written by Yeunwoo Cho. This book was released on 2004. Available in PDF, EPUB and Kindle. Book excerpt: A model was developed to study engine oil vaporization and oil vapor transport in the piston ring pack of internal combustion engines. With the assumption that the multi-grade oil can be modeled as a compound of several distinct paraffin hydrocarbons, a set of equations governing the oil vapor density variations were derived by applying the mass conservation law to the amount of oil vaporized from the piston and the amount of oil vapor transported within the piston ring pack. The model was applied to a heavy-duty diesel engine. First, the case with the maximum oil supply to all the piston regions was studied and the results showed that, under this condition, the oil consumption from vaporization alone was far greater than the typical oil consumption value measured in the engine. Then, to show the contribution of oil vaporization to oil consumption and the dependence of vaporization on oil supply to different regions, different lubrication conditions for the high temperature regions of the piston were studied. Finally, a liquid oil transport model was integrated with this oil vaporization model in order to investigate the change of oil composition on the crown land with each engine cycle and the contribution of liquid-phase oil and vapor-phase oil to the total oil consumption under a fixed liquid oil supply rate to the crown land.

Modeling Internal Combustion Engine Three-piece Oil Control Ring Coupling Reduced Order Oil Transport Based on Neural Network

2020
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Release : 2020
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Book Synopsis Modeling Internal Combustion Engine Three-piece Oil Control Ring Coupling Reduced Order Oil Transport Based on Neural Network by : Wang Zhang (S.M.)

Download or read book Modeling Internal Combustion Engine Three-piece Oil Control Ring Coupling Reduced Order Oil Transport Based on Neural Network written by Wang Zhang (S.M.). This book was released on 2020. Available in PDF, EPUB and Kindle. Book excerpt: Reducing emission and improving efficiency of internal combustion engines are the major focuses in modern automotive industry. Lubrication oil leakage contributes to particle formation and piston ring friction occupies 1/3 to 1/2 of total mechanical losses in engines. In almost all of modern gasoline engines, three-piece oil control ring (TPOCR) is used considering its low-cost and satisfying oil control performance in low load work conditions. While TPOCR will see high oil consumption at high load, high speed working conditions. This raises our interest in modeling work to predict the TPOCR dynamics and oil transport and explain the oil control mechanism. This master thesis work is focusing on building a three-piece oil control ring model coupling the oil transport. First, a 2D dynamics model for three pieces is established as the main frame. Second, oil transport in different zones will be modelled in different ways considering the length scales. Specially for the oil movement behind the ring, a novel approach is introduced by using neural networks to learn and run the reduced order modeling of computational fluid dynamics (CFD), to speed up the calculation. The model is then applied on a 2D laser induced fluorescence (2DLIF) engine and produces consistent simulation results with experimental observation. Further parametric study on oil transport will be discussed to build a complete picture of oil transport around TPOCR.

Modeling the Performance of the Piston Ring-pack with Consideration of Non-axisymmetric Characteristics of the Power Cylinder System in Internal Combustion Engines

2005
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Release : 2005
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Book Synopsis Modeling the Performance of the Piston Ring-pack with Consideration of Non-axisymmetric Characteristics of the Power Cylinder System in Internal Combustion Engines by : Liang Liu

Download or read book Modeling the Performance of the Piston Ring-pack with Consideration of Non-axisymmetric Characteristics of the Power Cylinder System in Internal Combustion Engines written by Liang Liu. This book was released on 2005. Available in PDF, EPUB and Kindle. Book excerpt: (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.

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