A Literature Review of the Effects of Piston and Ring Friction and Lubricating Oil Viscosity on Fuel Economy

McGeehan, J. A.

doi:10.4271/780673

Cited by 102 publications

(27 citation statements)

References 33 publications

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“…Its modeling is, however, difficult due to the interchanging nature of lubrication (boundary, mixed, hydrodynamic) and the large number of components, i.e. piston rings, piston skirt, loaded bearings, valve train and auxiliaries that cannot be easily isolated, experimentally investigated, and studied separately even at steady-state conditions [10,11]. Moreover, during transient operation, it is believed that friction is characterized by non steady-state behavior, differentiating engine response and performance when compared to the corresponding steady-state values, i.e.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Various Dynamic Issues During Transient Operation of Turbocharged Diesel Engine with Special Reference to Friction Development

Rakopoulos¹,

Giakoumis²,

Dimaratos³

2007

SAE Technical Paper Series

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The modeling of transient turbocharged diesel engine operation appeared in the early seventies and continues to be in the focal point of research, due to the importance of transient response in the everyday operating conditions of engines. The majority of research has focused so far on issues concerning thermodynamic modeling, as these directly affect heat release predictions and consequently performance and pollutants emissions. On the other hand, issues concerning the dynamics of transient operation are often disregarded or over-simplified, possibly for the sake of speeding up program execution time. In the present work, an experimentally validated transient diesel engine simulation code is used to study and evaluate the importance of such dynamic issues. First of all, the development of various forces (piston, connecting rod, crank and main crankshaft bearings) is computed and illustrated in order to evaluate the importance of abrupt load increases on the bearings durability. The usual approximation of the connecting rod being considered as equivalent to two masses (one reciprocating with the piston and the other rotating with the crank) is put into test. The same holds true for another usual assumption, i.e. the crankshaft being considered as sufficiently rigid. In this work, the engine crankshaft is analyzed in detail with the instantaneous torsional angle between engine and load taken into account. Thus, details are provided concerning the development of crankshaft torsional deformation during transients. The main part of the paper focuses on the development and contribution of various friction components during turbocharged diesel engine transients. This is accomplished via the use of a recently proposed detailed friction model. Mean fmep (friction mean effective pressure) modeling is found to considerably underestimate actual friction around firing TDC, leading to lower speed droops for abrupt load increases. The piston rings assembly contribution is dominant for the particular engine, due to its high number of piston rings and its relatively low crankshaft speed. The model can be used to investigate such interesting cases as the effect of engine oil temperature on engine transient response, or the variation of oil film thickness during a cycle or a transient event.

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Section: Introductionmentioning

confidence: 99%

Evaluation of Various Dynamic Issues During Transient Operation of Turbocharged Diesel Engine with Special Reference to Friction Development

Rakopoulos¹,

Giakoumis²,

Dimaratos³

2007

SAE Technical Paper Series

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“…Rubbing friction occurs wherever there is relative movement between surfaces: in bearings, seals, cam followers, and so on. These various sources can be grouped into three sets associated with piston, crankshaft, and valve train component assemblies, respectively, of which the piston component assembly makes the largest contribution to the engine total friction loss [3][4][5][6][7][8][9]. The friction losses associated with the piston assembly and piston motion relative to the liner have been of particular interest during the investigation reported here, in which an experimental study was carried out to examine how friction losses depend upon engine speed, liner temperature, oil viscosity, and design features.…”

Section: Introductionmentioning

confidence: 99%

Characterizing the effect of viscosity on friction in the piston assembly of internal combustion engines

Leong

Shayler

Pegg

et al. 2007

Proceedings of the Institution of Mechanical Engineers, Part J:

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The friction mean effective pressure (fmep) contribution of piston assemblies running under motored engine conditions in cylinders with plateau or laser honed bores has been investigated. Results have been obtained for engine speeds in the range 400-2000 r/min and temperatures from −20 to around 60 • C. The fmep of the piston assembly is observed to depend most directly on oil viscosity evaluated at the temperature of the cylinder wall at mid-stroke position. The variation of fmep with viscosity provides a basis for comparing the effects of surface finish or piston design modifications. Using liners with fine honed bores reduced piston assembly friction by between 3 and 20 per cent relative to results for pistons running in plateau honed bores. Piston assembly friction was reduced by between 5 and 38 per cent through design changes to the pistons.

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“…The top ring has a barrel-shaped face profile, which has been shown to be most effective for lubrication [5]. Sufficient lubrication is critical for the top ring as it is subjected to the high cylinder pressures, which can result in large radial forces acting on the back of the ring.…”

Section: Description Of the Piston Ring-liner Systemmentioning

confidence: 99%

“…MIT's computer models [1][2][3][4][5] have been applied to target the most important contributors to friction in the piston-cylinder assembly of the engine. Specifically, three models were applied to analyze the behavior of the piston rings and these are described in some detail in the section that follows.…”

Section: Overviewmentioning

confidence: 99%

Low-Engine-Friction Technology for Advanced Natural-Gas Reciprocating Engines

Wong¹,

Tian²,

Moughon³

et al. 2004

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This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston/ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and emissions. An iterative process of simulation, experimentation and analysis, are being followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. To date, a detailed set of piston/ring dynamic and friction models have been developed and applied that illustrated the fundamental relationships between design parameters and friction losses. Various lowfriction strategies and ring-design concepts have been explored, and engine experiments have been done on a full-scale Waukesha VGF F18 in-line 6 cylinder power generation engine rated at 370 kW at 1800 rpm.Current accomplishments include designing and testing ring-packs using a subtle topcompression-ring profile (skewed barrel design), lowering the tension of the oil-control ring, employing a negative twist to the scraper ring to control oil consumption. Initial test data indicate that piston ring-pack friction was reduced by 35% by lowering the oil-control ring tension alone, which corresponds to a 1.5% improvement in fuel efficiency. Although small in magnitude, this improvement represents a first step towards anticipated aggregate improvements from other strategies. Other ring-pack design strategies to lower friction have been identified, including reduced axial distance between the top two rings, tilted top-ring groove. Some of these configurations have been tested and some await further evaluation. Colorado State University performed the tests and Waukesha Engine Dresser, Inc. provided technical support.Key elements of the continuing work include optimizing the engine piston design, application of surface and material developments in conjunction with improved lubricant properties, system modeling and analysis, and continued technology demonstration in an actual full-sized reciprocating natural-gas engine.-3 -

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A Literature Review of the Effects of Piston and Ring Friction and Lubricating Oil Viscosity on Fuel Economy

Cited by 102 publications

References 33 publications

Evaluation of Various Dynamic Issues During Transient Operation of Turbocharged Diesel Engine with Special Reference to Friction Development

Evaluation of Various Dynamic Issues During Transient Operation of Turbocharged Diesel Engine with Special Reference to Friction Development

Characterizing the effect of viscosity on friction in the piston assembly of internal combustion engines

Low-Engine-Friction Technology for Advanced Natural-Gas Reciprocating Engines

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