Dynamic behaviours of piston rings and their practical impact. Part 2: Oil transport, friction and wear of ring/liner interface and the effects of piston and ring dynamics

2002 ◽  
Vol 216 (4) ◽  
pp. 229-248 ◽  
Author(s):  
T Tian
Keyword(s):  
Friction And Wear ◽  
Surface Profile ◽  
Theoretical Models ◽  
Heavy Duty ◽  
Oil Consumption ◽  
Oil Supply ◽  
Oil Transport ◽  
Ring Dynamics ◽  
Calculation Results ◽  
Practical Impact

The paper discusses several important processes that have great impact on the lubrication between the top two rings and the liner. The analysis is conducted on the basis of the calculation results on a heavy-duty (HD) diesel engine using theoretical models. Oil supply mechanisms to different liner regions are analysed, and emphasis is given to the oil transport to the top liner region that is found critical to friction, wear and oil consumption in HD diesel engines. Additionally, the paper discusses the oil supply to the second ring, its uncertainties and the effect on the prediction of the performance of the top two rings. Furthermore, the effects of dynamics of the piston and rings on friction, wear and oil transport are illustrated and the effects of bore distortion on oil transport are discussed. For practical purposes, a formula to describe the second ring running surface profile is given based on simple geometrical constraint. A new truncation method is rendered for plateau surface roughness in order to effectively use the existing mixed lubrication models.

Numerical Study on the Tribological Performance of Ring/Liner System With Consideration of Oil Transport

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Cheng Liu ◽  
Yanjun Lu ◽  
Yongfang Zhang ◽  
Sha Li ◽  
Jianxiong Kang ◽  
...  
Keyword(s):  
Transport Model ◽  
Numerical Study ◽  
Great Influence ◽  
Cylinder Liner ◽  
Tribological Performance ◽  
Oil Consumption ◽  
Oil Supply ◽  
Oil Transport ◽  
Liner System ◽  
Lubrication Condition

The tribological performance of a compression ring-cylinder liner system (CRCL) is numerically studied. A thermal-mixed lubrication model is developed for the lubrication analysis of the CRCL with consideration of the cylinder liner deformation. An oil transport model coupled with a mass conservation cavitation algorithm is employed to predict the oil consumption and the transition between the fully flooded lubrication condition and starved lubrication condition. On this basis, the effects of the oil supply and cylinder liner deformation on the frictional characteristics are investigated under cold and warm engine conditions. The results show that the cylinder liner deformation and oil supply have great influence on the tribological performance of the CRCL. Better tribological performance and lower oil consumption can be obtained by reasonably controlling the oil supply.

The Dynamics of Second Ring Flutter and Collapse in Modern Diesel Engines

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Chao Cheng ◽  
Harold Schock ◽  
Dan Richardson
Keyword(s):  
Diesel Engine ◽  
Gas Flow ◽  
Piston Ring ◽  
Sensitivity Study ◽  
The Other ◽  
Heavy Duty ◽  
Oil Consumption ◽  
Ring Dynamics ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel

Second ring fluttering and radial ring collapse are recognized as having significant influences on engine blowby and oil consumption. As the gas flow is coupled with the piston ring motion, understanding the ring dynamics is important for understanding not only the engine blowby mechanism, but also oil consumption mechanisms and how to control them. Only second ring flutter and collapse that occurs around the top dead center (TDC) firing conditions is examined in this paper based on a modern heavy-duty diesel engine. However, the principles described are equally applicable to all engines. First, the authors describe the fundamental mechanisms of how second ring fluttering and radial ring collapse occur. This is described by examining the forces that are acting on the second ring. Then, two cases are shown. One case shows second ring flutter and the other case shows stable second ring motion. The reasons for these two different cases are explained, including the effect of static twist and the end gaps of the rings. A sensitivity study was performed to evaluate the effect of changing the top and second ring end gaps on ring lift. It was shown how the gaps could affect the second ring flutter and ring collapse. It is concluded that the second ring will be more likely to flutter or collapse if it has a negative static twist, if the second ring end gap is large, and/or if the top ring end gap is small. If the second ring does not flutter, it may still be possible to design the ring pack such that there is not any reverse blowby. However, this must be carefully studied and controlled or the second land pressures will be too high, resulting in reverse blowby and/or top ring lifting.

The Dynamics of Second Ring Flutter and Collapse in Modern Diesel Engines

2014 ◽  
Author(s):  
Chao Cheng ◽  
Harold Schock ◽  
Dan Richardson
Keyword(s):  
Diesel Engine ◽  
Gas Flow ◽  
Piston Ring ◽  
Sensitivity Study ◽  
The Other ◽  
Heavy Duty ◽  
Oil Consumption ◽  
Ring Dynamics ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel

Second ring fluttering and radial ring collapse are recognized as having significant influences on engine blowby and oil consumption. As the gas flow is coupled with the piston ring motion, understanding the ring dynamics is important for understanding not only the engine blowby mechanism, but also oil consumption mechanisms and how to control them. Only second ring flutter and collapse that occurs around the top dead center firing conditions is examined in this paper based on a modern heavy-duty diesel engine. However, the principles described are equally applicable to all engines. First, the authors describe the fundamental mechanisms of how second ring fluttering and radial ring collapse occurs. This is described by examining the forces that are acting on the second ring. Then, two cases are shown. One case shows second ring flutter and the other case shows stable second ring motion. The reasons for these two different cases are explained, including the effect of static twist and the end gaps of the rings. A sensitivity study was performed to evaluate the effect of changing the top and second ring end gaps on ring lift. It was shown how the gaps could affect the second ring flutter and ring collapse. It is concluded that the second ring will be more likely to flutter or collapse if it has a negative static twist, if the second ring end gap is large, and/or if the top ring end gap is small. If the second ring does not flutter, it may still be possible to design the ring pack such that there is not any reverse blowby. However, this must be carefully studied and controlled or the second land pressures will be too high, resulting in reverse blowby and/or top ring lifting.

Dynamic behaviours of piston rings and their practical impact. Part 1: Ring flutter and ring collapse and their effects on gas flow and oil transport

2002 ◽  
Vol 216 (4) ◽  
pp. 209-228 ◽  
Author(s):  
T Tian
Keyword(s):  
Gas Flow ◽  
Great Influence ◽  
Spark Ignition Engine ◽  
Torsional Stiffness ◽  
Critical Parameters ◽  
Oil Consumption ◽  
Piston Rings ◽  
Ring Groove ◽  
Oil Transport ◽  
Heavy Duty Diesel

This paper describes the physics of two major dynamic behaviours of the piston rings, namely ring flutter and ring collapse, and their effects on gas flow and oil transport. The analysis was conducted by applying a theoretical model in a spark ignition engine and a heavy-duty diesel engine. Parameters that have great influence on these dynamic behaviours are discussed for these two different types of engine and different rings. Specifically, the importance of ring twist, torsional stiffness and ring-groove clearance to ring flutter are discussed in detail. For ring radial collapse, the paper presents a simple formula that determines value of the critical parameters to eliminate ring radial collapse. Emphases are placed on the importance of mechanical designs in changing the performance of the piston ring pack in blowby and oil consumption.

Investigation of Friction and Wear of Dynamically Loaded Hydrodynamic Bearings With Abrasive Contaminants

1983 ◽  
Vol 105 (4) ◽  
pp. 559-567 ◽  
Author(s):  
A. Ronen ◽  
S. Malkin
Keyword(s):  
Dynamic Loading ◽  
Friction And Wear ◽  
Wear Behavior ◽  
Test System ◽  
Hydrodynamic Bearings ◽  
Abrasive Particles ◽  
Oil Supply ◽  
Dynamic Loading Conditions ◽  
Supply Systems ◽  
Bearing Friction

A test system is described for investigating friction and wear of hydrodynamic bearings under cyclical dynamic loading conditions with contaminant abrasive particles in the oil supply. Dynamic loading on the test bearing is synchronized with the shaft rotation, so that the oil film thickness history can be determined from the measured shaft orbit for any point on the shaft and liner periphery. Either clean or contaminated oil can be supplied to the test bearing from two separate oil supply systems. Experimental results obtained for six shaft/liner bearing material combinations were similar to those previously obtained for static loading. The friction and wear behavior were found to depend on the relative hardnesses of the shaft and liner. A larger shaft-to-liner hardness ratio generally resulted in more shaft wear and less liner wear. This is attributed to an increased tendency for abrasive particles to partially embed in the liner and cut the shaft when the shaft is harder and/or the liner is softer. With partial embedding, high bearing friction indicative of continuing abrasion persists after changing from contaminated to clean oil.

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