Numerical analysis of the effects of compression ring wear and cylinder liner deformation on the thermal mixed lubrication performance of ring-liner system

Abstract

The lubrication performance of roughness compression ring-cylinder liner system (CRCL) with axial-asymmetric new/worn compression ring and out-of-round cylinder liner is studied in this paper. By considering the oil film thermal effect, cavitation phenomenon, and surface roughness, the energy equations, mass conservation Jacoboson-Floberg-Olsson (JFO) cavitation algorithm, generalized average Reynolds equation, and Greenwood-Tripp asperity contact model are employed to investigate the frictional behaviors of CRCL. The oil film thickness, friction forces, wear, and power loss of CRCL are investigated at various wear stages of compression ring. The effects of the magnitude of cylinder liner deformation on the frictional characteristics of CRCL are also analyzed with consideration of compression ring conformability. Numerical results show that the deformation of cylinder liner and the wear of compression ring have a significant influence on the lubrication performance. It also suggests that the oil film thermal effect should be considered in the numerical analysis to provide an accurate prediction on the frictional behaviors of CRCL.

Improving frictional performance of ring-liner system under cylinder deactivation conditions by surface texturing

“…During the operation of the RLS, to seal the high-temperature gas in the combustion chamber well, the ring will elastically deform to fit the liner profile under the actions of tension force and backpressure force, and the elastic deformation of the ring can be described by 22,24…”

“…τ 0 is the constant related to shear stress, α 0 is the coefficient related to boundary friction, and τ 0 = 2 MPa and α 0 = 0.17 are used based on the previous works. 13,22 F asp and A c represent the contact force and area of asperities, and their expressions can be obtained according to an asperity contact model.…”

“…31 Meanwhile, the ring also elastically deforms under the actions of backpressure force and tension force, and then reduces the gap between the ring and the deformed liner. Hence, the gap between the surface textured ring and liner caused by liner deformation can be described by 22,31…”

“…Moreover, it should be noticed that the liner under the actual working conditions is usually out-of-round because of the inevitable deformation. 22 Meanwhile, fully flooded and starved lubrication conditions are possible to coexist in the engine cycle of the RLS. 23 Therefore, Usman and Park 24 conducted a research on the frictional properties of the dimple textured RLS with a non-circular liner, and a significant friction-reducing effect was observed in the middle of the strokes.…”

Effect of surface texture on the improvement of tribological performance of ring‐deformed liner conjunction under different oil supplies

“…Owing to the increasingly stringent exhaust emission regulation and oil consumption criteria, there is an urgent need to reduce friction of ring‐liner conjunction in modern ICEs (internal combustion engines) because its friction contributes greatly to the oil consumption and exhaust emission . In recent years, with the evolution of advanced surface treatment technology, the ring or liner textured with some well‐designed functional micro features (eg, dimple and groove) has been experimentally proved to reduce the friction loss effectively .…”