Negative Pressures under a Lubricated Piston Ring

1978 ◽  
Vol 20 (1) ◽  
pp. 49-57 ◽  
Author(s):  
S. R. Brown ◽  
G. M. Hamilton
Keyword(s):  
Film Thickness ◽  
Piston Ring ◽  
Oil Film ◽  
Short Period ◽  
Minimum Film Thickness ◽  
Negative Pressures ◽  
The Dead ◽  
Peak Value ◽  
Dead Centre

Large negative pressures have been observed in the oil film lubricating a piston ring. Just after the dead-centre position, these reach a peak value of −0.78 MN/m2 (-113.1 lbf/in2), which is far in excess of the values normally assumed to be needed to produce cavitation. They are only sustained for a short period of time, but have the important effect of reducing the minimum film thickness.

scholarly journals The Piston Ring-Cylinder Bore Interface Leakage of Bent-Axis Piston Pumps Based on Elastohydrodynamic Lubrication and Rotation Speed

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Lvjun Qing ◽  
Lichen Gu ◽  
Yan Wang ◽  
Wei Xue ◽  
Zhufeng Lei
Keyword(s):  
Film Thickness ◽  
Piston Ring ◽  
Rotation Speed ◽  
Elastohydrodynamic Lubrication ◽  
Oil Film ◽  
Proposed Model ◽  
Minimum Film Thickness ◽  
Oil Flow ◽  
Discharge Pressure ◽  
Cylinder Bore

The bent-axis piston pump is the core component of electrohydrostatic actuators (EHA) in aerospace applications, and its wear of key friction interfaces is greatly related to the healthy operation of pumps. The leakage of the piston ring-cylinder bore interface (PRCB), as the important part of the return oil flow of the pump house that commonly assesses the wear of key friction interfaces in piston pumps, is changed with the rotation speed. Thus, the wear of key friction interfaces is usually inaccurate by using the leakage of PRCB. In order to obtain the relationship between the PRCB leakage and the rotation speed, an elastohydrodynamic lubrication model is proposed. First, the proposed model includes a minimum film thickness model of PRCB to analyze the dynamic change of oil film of PRCB when subject to the elastohydrodynamic lubrication. After that, a mathematical model of PRCB is induced by combining the minimum film thickness model with the flow equation, which helps produce the effects of the oil film on the leakage of PRCB. The proposed model is verified by numerical simulation and experiment. The results show that the leakage of PRCB has a negative effect on the return oil flow of the pump case in the range of rotation speed of 700–1300 r/min and discharge pressure of 10–20 MPa. Furthermore, the leakage of PRCB is proportional to the rotation speed, but the return oil flow of the pump case is decreased. The effects of rotation speed are enhanced under the high discharge pressure conditions.

The Piston Ring at Top Dead Centre

1980 ◽  
Vol 194 (1) ◽  
pp. 373-381 ◽  
Author(s):  
S. L. Moore ◽  
G. M. Hamilton
Keyword(s):  
Diesel Engine ◽  
Film Thickness ◽  
Piston Ring ◽  
Cylinder Liner ◽  
The Other ◽  
Oil Film ◽  
Compression Ring ◽  
Capacitance Transducers ◽  
Dead Centre

Using capacitance transducers the oil film thickness between the compression ring and the cylinder liner of a diesel engine has been investigated in the region of top dead centre. Results are presented from two engines, one supercharged and the other normally aspirated. Calculations of the film thickness have been carried out and these are compared with the measured results.

Predictive tool for frictional performance of piston ring-pack/liner conjunction

2019 ◽  
Vol 13 (3) ◽  
pp. 5513-5527
Author(s):  
J. W. Tee ◽  
S. H. Hamdan ◽  
W. W. F. Chong
Keyword(s):  
Film Thickness ◽  
Mathematical Models ◽  
Piston Ring ◽  
Published Data ◽  
Predictive Tool ◽  
Frictional Losses ◽  
Fundamental Understanding ◽  
Minimum Film Thickness ◽  
Piston Ring Pack ◽  
Ring Pack

Fundamental understanding of piston ring-pack lubrication is essential in reducing engine friction. This is because a substantial portion of engine frictional losses come from piston-ring assembly. Hence, this study investigates the tribological impact of different piston ring profiles towards engine in-cylinder friction. Mathematical models are derived from Reynolds equation by using Reynolds’ boundary conditions to generate the contact pressure distribution along the complete piston ring-pack/liner conjunction. The predicted minimum film thickness is then used to predict the friction generated between the piston ring-pack and the engine cylinder liner. The engine in-cylinder friction is predicted using Greenwood and Williamson’s rough surface contact model. The model considers both the boundary friction and the viscous friction components. These mathematical models are integrated to simulate the total engine in-cylinder friction originating from the studied piston ring-pack for a complete engine cycle. The predicted minimum film thickness and frictional properties from the current models are shown to correlate reasonably with the published data. Hence, the proposed mathematical approach prepares a simplistic platform in predicting frictional losses of piston ring-pack/liner conjunction, allowing for an improved fundamental understanding of the parasitic losses in an internal combustion engine.

Influence of Surface Waviness on the Thermal Elastohydrodynamic Lubrication of an Eccentric-Tappet Pair

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
J. Wang ◽  
C. H. Venner ◽  
A. A. Lubrecht
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Surface Waviness ◽  
Film Pressure ◽  
Oil Film ◽  
Working Cycle ◽  
Temperature Oscillations ◽  
Minimum Film Thickness ◽  
Traction Coefficient ◽  
Oil Film Pressure

The effect of single-sided and double-sided harmonic surface waviness on the film thickness, pressure, and temperature oscillations in an elastohydrodynamically lubricated eccentric-tappet pair has been investigated in relation to the eccentricity and the waviness wavelength. The results show that, during one working cycle, the waviness causes significant fluctuations of the oil film, pressure, and temperature, as well as a reduction in minimum film thickness. Smaller wavelength causes more dramatic variations in oil film. The fluctuations of the pressure, film thickness, temperature, and traction coefficient caused by double-sided waviness are nearly the same compared with the single-sided waviness, but the variations are less intense.

Analysis of Tribological Performance of Piston Ring Lubrication

2011 ◽  
Author(s):  
Yibin Guo ◽  
Wanyou Li ◽  
Dequan Zou ◽  
Xiqun Lu ◽  
Tao He
Keyword(s):  
Film Thickness ◽  
Friction Force ◽  
Power Loss ◽  
Piston Ring ◽  
Design Parameters ◽  
Oil Film ◽  
Starved Lubrication ◽  
Piston Ring Lubrication ◽  
Cylinder Bore ◽  
Lubrication Conditions

In this paper a mixed lubrication model considering lubricant supply conditions on cylinder bore has been developed for the piston ring lubrication. The numerical procedures of both fully flooded and starved lubrication were included in the model. The lubrication equations and boundary conditions at the end of strokes were discussed in detail. The effects of piston ring design parameters, such as ring face profile and ring tension, on oil film thickness, friction force and power loss under fully flooded and starved lubrication conditions due to available lubricant supply on cylinder bore were studied. The simulation results show that the oil available in the inlet region of the oil film is important to the piston ring friction power loss. With different ring face crown heights and tensions, the changes of oil film thickness and friction force were apparent under fully flooded lubrication, but almost no changes were found under starved lubrication except at the end of a stroke. In addition, the oil film thickness and friction force were affected evidently by the ring face profile offsets under both fully flooded and starved lubrication conditions, and the offset towards the combustion chamber made a large contribution to forming thicker oil film during the expansion stroke. So under different lubricant supply conditions on the cylinder bore, the ring profile and tension need to be adjusted to reduce the friction and power loss. Moreover, the effects of lubricant viscosity, surface composite roughness, and engine operating speed on friction force and power loss were also discussed.

Measurement of Piston Ring Oil Film Thickness in an Operating Engine

1983 ◽  
Vol 26 (3) ◽  
pp. 325-332 ◽  
Author(s):  
Shoichi Furuhama ◽  
Chikashi Asahi ◽  
Masaru Hiruma
Keyword(s):  
Film Thickness ◽  
Piston Ring ◽  
Oil Film

Analysis of Oil Film Thickness on a Piston Ring of Diesel Engine: Effect of Oil Film Temperature

2001 ◽  
Author(s):  
Yasuo Harigaya ◽  
Michiyoshi Suzuki ◽  
Masaaki Takiguchi
Keyword(s):  
Diesel Engine ◽  
Temperature Distribution ◽  
Heat Flow ◽  
Film Thickness ◽  
Piston Ring ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Two Dimensional ◽  
Oil Film ◽  
The Mean

Abstract This paper describes that an analysis of oil film thickness on a piston ring of diesel engine. The oil film thickness has been performed by using Reynolds equation and unsteady, two-dimensional (2-D) energy equation with a heat generated from viscous dissipation. The temperature distribution in the oil film is calculated by using the energy equation and the mean oil film temperature is computed. Then the viscosity of oil film is estimated by using the mean oil film temperature. The effect of oil film temperature on the oil film thickness of a piston ring was examined. This model has been verified with published experimental results. Moreover, the heat flow at ring and liner surfaces was examined. As a result, the oil film thickness could be calculated by using the viscosity estimated from the mean oil film temperature and the calculated value is agreement with the measured values.

Development of a Laser Fluorescence Technique For Measuring Piston Ring Oil Film Thickness

1980 ◽  
Vol 102 (2) ◽  
pp. 165-170 ◽  
Author(s):  
L. L. Ting
Keyword(s):  
Light Intensity ◽  
Film Thickness ◽  
Piston Ring ◽  
Laser Fluorescence ◽  
Engine Oil ◽  
Fluorescent Light ◽  
Fluorescence Technique ◽  
Thickness Change ◽  
Oil Film ◽  
Cylinder Sleeve

A single cylinder engine equipped with a transparent cylinder sleeve has been used to develop a technique to make visual investigations of piston ring lubrication behavior and engine oil loss mechanism. This paper describes this apparatus and the development of a laser excited oil fluorescence technique for measuring the oil film thickness change between the piston rings and the transparent cylinder sleeve wall. The amount of oil accumulated in the piston-cylinder clearance spaces above and below the ring pack, and those in the inter-ring spaces, can also be observed. Preliminary results showing oil fluorescence light intensity traces indicate that this technique works very well. Quantitative oil film thickness data should be readily obtainable from these traces once the fluorescent light intensity is calibrated.

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