Three-Dimensional Piston Ring–Cylinder Bore Contact Modeling

Author(s):  
Chao Cheng ◽  
Ali Kharazmi ◽  
Harold Schock ◽  
Richard Wineland ◽  
Larry Brombolich

Increasing durability, preventing knocking combustion, improving fuel efficiency, and reducing pollutant emission characterize the needs for modern internal combustion engine design. These factors are highly influenced by the power cylinder system design. In particular, the piston ring to cylinder bore contact force distribution around the circumference of the piston rings must be optimized under all running conditions. To accomplish this, the ring manufacturers make the ring curvature nonconstant along the circumference. Most existing analytical tools are not able to simulate the variation along the ring circumference. In order to improve the understanding of this contact distribution and provide a high-fidelity ring design tool, a three-dimensional finite element piston ring model was developed to accomplish this variation. The modeling procedure and results are presented in this work. Experiments using a commercially available ring with negative ovality were conducted to validate the model. The ring free-shape profile and the ring cross section geometries were used as inputs to the model. Typical piston ring groove and cylinder wall temperatures were also model inputs to characterize thermal influences on the ring/bore interface forces. The ring/bore conformability was analyzed as a function of the ring radial displacements, cylinder bore constraint forces and thermal load changes to the ring. The model output showed radially separation gaps between the ring front face and the bore. This analysis provides an insight to evaluate the piston ring design. Together with an optimizer, the model can be used as a ring design tool to predict the ring free shape with a specified constraint force distribution pattern. Examples are given to demonstrate the capabilities of this numerical analytical tool. In addition, the 3D ring model can be used to improve the accuracy of existing lubrication, friction, and wear analysis tools and therefore improve the entire internal combustion engine power cylinder system design.

Author(s):  
Chao Cheng ◽  
Ali Kharazmi ◽  
Harold Schock ◽  
Richard Wineland ◽  
Larry Brombolich

Increasing durability, preventing knocking combustion, improving fuel efficiency and reducing pollutant emission characterize the needs for modern internal combustion engine design. These factors are highly influenced by the power cylinder system design. In particular, the piston ring to cylinder bore contact force distribution around the circumference of the piston rings must be optimized under all running conditions. To accomplish this, the ring manufacturers make the ring curvature non-constant along the circumference. Most existing analytical tools are not able to simulate the variation along the ring circumference. In order to improve the understanding of this contact distribution and provide a high-fidelity ring design tool, a three-dimensional finite element piston ring model was developed to accomplish this variation. The modeling procedure and results are presented in this work. Experiments using a commercially available ring with negative ovality were conducted to validate the model. The ring free shape profile and the ring cross-section geometries were used as inputs to the model. Typical piston ring groove and cylinder wall temperatures were also model inputs to characterize thermal influences on the ring/bore interface forces. The ring/bore conformability was analyzed as a function of the ring radial displacements, cylinder bore constraint forces and thermal load changes to the ring. The model output showed radially separation gaps between the ring front face and the bore. This analysis provides an insight to evaluate the piston ring design. Together with an optimizer, the model can be used as a ring design tool to predict the ring free shape with a specified constraint force distribution pattern. Examples are given to demonstrate the capabilities of this numerical analytical tool. In addition, the 3D ring model can be used to improve the accuracy of existing lubrication, friction and wear analysis tools and therefore improve the entire internal combustion engine power cylinder system design.


2019 ◽  
Vol 71 (4) ◽  
pp. 515-524 ◽  
Author(s):  
Venkateswara Babu P. ◽  
Ismail Syed ◽  
Satish Ben Beera

Purpose In an internal combustion engine, piston ring-cylinder liner tribo pair is one among the most critical rubbing pairs. Most of the energy produced by an internal combustion engine is dissipated as frictional losses of which major portion is contributed by the piston ring-cylinder liner tribo pair. Hence, proper design of tribological parameters of piston ring-cylinder liner pair is essential and can effectively reduce the friction and wear, thereby improving the tribological performance of the engine. This paper aims to use surface texturing, an effective and feasible method, to improve the tribological performance of piston ring-cylinder liner tribo pair. Design/methodology/approach In this paper, influence of positive texturing (protruding) on friction reduction and wear resistance of piston ring surfaces was studied. The square-shaped positive textures were fabricated on piston ring surface by chemical etching method, and the experiments were conducted with textured piston ring surfaces against un-textured cylinder liner surface on pin-on-disc apparatus by continuous supply of lubricant at the inlet of contact zone. The parameters varied in this study are area density and normal load at a constant sliding speed. A comparison was made between the tribological properties of textured and un-textured piston ring surfaces. Findings From the experimental results, the tribological performance of the textured piston ring-cylinder liner tribo pair was significantly improved over a un-textured tribo pair. A maximum friction reduction of 67.6 per cent and wear resistance of 81.6 per cent were observed with textured ring surfaces as compared to un-textured ring surfaces. Originality/value This experimental study is helpful for better understanding of the potency of positive texturing on friction reduction and wear resistance of piston ring-cylinder liner tribo pair under lubricated sliding conditions.


2013 ◽  
Vol 787 ◽  
pp. 704-710 ◽  
Author(s):  
Kellaci Ahmed ◽  
Khelidj Benyoucef ◽  
Mazouzi Redha ◽  
Lounis Mourad

This investigation is concerned with the elastohydrodynamic lubrication of the piston skirt / cylinder link of an internal combustion engine. In such compliant structures, the thickness of the lubricant film depends not only on the elastic deformation elements of the mechanism but also on their profiles. We have developed a computer program to study the effect of the profile of the piston skirt on the lubricant film. This program is based on a two-dimensional description of the lubricant film flow and a three-dimensional deformation of solids. The Reynolds equation defines the behavior of hydrodynamic film of oil in the liaison piston skirt / cylinder, and the equations of static and elastic equilibrium quantify the behavior of the structure. These Equations are solved numerically by using the finite differences method.


Author(s):  
Boon-Keat Chui ◽  
Harold J. Schock ◽  
Andrew M. Fedewa ◽  
Dan E. Richardson ◽  
Terry Shaw

The cylinder-kit assembly of an internal combustion engine experiences severe conditions during engine operation. The top compression ring, in particular, undergoes extreme stress directly from cylinder gas pressure, inertial and thermal loads. The top compression ring is often the most significantly affected piston ring, and one of the common resultant phenomena is high wear on the ring/bore surfaces. In many previous studies, the modeling of tribological phenomena at the top compression ring/bore region involves hydrodynamic and boundary lubrication, friction and wear. This present work accounts for an additional factor that may affect the piston ring/bore lubrication — the lubricant evaporative effect. A three-dimensional oil evaporative analysis is coupled into the calculation of mixed lubrication in a cyclic engine computation. The presence of the evaporation analysis allows the study of the temperature influence on the piston ring/bore lubrication in addition to its effect on oil viscosity. A prospective application of this model is in diesel engine analysis. Considering the broad operating range of modern diesel fuel injection systems, the injection timing can be made throughout the compression/expansion process. It is well demonstrated that certain areas of fuel injection operation can result in potential adverse consequences such as increased bore wear. A well known example is “bore wall fuel wetting.” Given concerns around the potential for wear-inducing interactions between the fuel injection plumes and the bore wall, we have explored a particular interaction: bore wear in response to an imposed local heating of the bore wall. The simulation result provides valuable insights on this interaction, in which higher bore wear is predicted around bore wall area with locally imposed wall heating.


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