Analysis of lubrication and friction for a complete piston-ring pack with an improved oil availability model: Part 1: Circumferentially uniform film

Abstract

The study of the tribological performance of piston rings plays an important role in piston assembly design. In this study, a comprehensive analysis of piston-ring pack lubrication has been developed. The model employs a flow-continuity algorithm and considers relative ring locations in the piston-ring pack as well as oil accumulation in front of the ring in determining the oil availability. The computer model is able to predict the effect that bore distortion and ring conformability have on piston-ring performance. (This influence is discussed in Part 2 of the paper). In this part of the paper (Part 1), the theoretical formulation of the model is briefly described. The model is verified through comparison of the calculated ring±liner film thicknesses with those measured experimentally by Hamilton and Moore on a diesel engine. Then some results, obtained under situations where film thicknesses are circumferentially uniform, are presented to simulate a piston-ring pack in a modern petrol engine as an example to demonstrate the capabilities of the model and to show the effects of some important factors on the performance characteristics of the ring pack. The authors have found that the model developed is a robust one which can be used to analyse the tribological performance of ring packs effectively in both circular and distorted cylinder bores of internal combustion (IC) engines.

In-cycle and life-time friction transience in piston ring–liner conjunction under mixed regime of lubrication

“…Since the initial analytical approach by Furuhama [2], there have been increasing levels of detail in predictive methods, including further salient practical features in the analysis tools. Initially, the improvements in analyses were as the result of a better understanding of regimes of lubrication and improvements in numerical procedures (Dowson et al [3], Ma et al [4], Akalin and Newaz [5], Bolander et al [6], Mishra et al [7,8], D'Agostino and Senatore [9] and Rahmani et al [10]). Good agreement is shown between the predicted and the measured friction presented by Furuhama and Sasaki [11] by a number of contributions such as those of Akalin and Newaz [12] and Mishra et al [8].…”

A hydrodynamic flow analysis for optimal positioning of surface textures

“…Various studies have shown that the generated pressures are insufficient to cause any appreciable localised deformation of the contiguous surfaces, thus the lubricant film thickness can be stated as [30][31][32]:…”

Effect of Compression Ring Elastodynamics Behaviour upon Blowby and Power Loss

“…From these reports, further studies on various aspects of the ring-liner conjunction have been carried out. Ma et al [16] and Mishra et al [17] examined ring-bore conformability. Ma concluded that bore distortion may reduce the power loss; however oil consumption would increase as a result.…”

“…Equation (16) shows the expression for the viscous shear, which varies at each point on the ring: (16) As the viscous shear is a function of film thickness, h, the value of viscous shear varies both circumferentially and axially.…”

“…Only the top ring is considered in this study. The mass flow rate from A to B is calculated as follows, using Reynolds equation for the gas, as well as the ideal gas law [29]: (16) where A 1 is the cross-sectional area for control volume A, h 1 is the distance between the liner and piston top land, l 1 is the top land height, P A is the cylinder pressure and P B,I is the initial pressure assumed in control volume B. The same methodology is used to calculate the mass flow rate through the other control volumes, although the cross-sectional areas of the control volumes may vary.…”