Contact Pressure Distribution of Piston Rings -Calculation Based on Piston Ring Contour -

Proceedings of the Institution of Mechanical Engineers, Part C:

Rahnejat

King

2008

112

This paper provides a detailed analysis of the compression ring—bore/liner conjunction. The analysis includes ring—bore conformability and global in-plane deformation of ring fitted in situ. The analysis for fitted ring in an out-of-round bore shows very good agreement with precise measurements, using a coordinate measuring machine. The analysis also includes the lubricated conjunction under a transient regime of lubrication, taking into account combined elastohydrodynamics and asperity interactions. The transient nature of the tribological conjunction has been demonstrated, particularly the prevalent mixed/boundary regime of lubrication at the top and bottom dead centres. The analysis is applied to a high performance motorbike engine subjected to very high impact loads and engine speeds of the order of 13 000 r/min. Furthermore, the predictions of the model show good conformance to the measurements of friction reported by other research workers.

Section: Calculation Of the Elastic Force Due To Global Radial Ring Dmentioning

confidence: 99%

Tribology of the ring—bore conjunction subject to a mixed regime of lubrication

Proceedings of the Institution of Mechanical Engineers, Part C:

Rahnejat

King

2008

112

“…Okamoto and Sakai [12] estimated the contact pressure distribution in the piston ring-bore conjunction by considering the ring as a beam element. They estimated the deformed ring shape using the bending moment concept, which is applied to a beam element fixed at one end (see Fig.…”

Section: Elastic Force Due To Ring Global Radial Deformationmentioning

confidence: 99%

“…The validation is sought in two steps. First, comparison is made with the work of Okamoto and Sakai [12] under the same conditions (Table 1). These are shown in Figs 4(a) and (b).…”

Section: Radial In-plane Ring Deformationmentioning

confidence: 99%

Tribology of compression ring-to-cylinder contact at reversal

Proceedings of the Institution of Mechanical Engineers, Part J:

Balakrishnan

Rahnejat

2008

Piston ring-pack-to-cylinder contact accounts for one of the major sources of frictional losses in internal combustion engines. The regime of lubrication alters during the piston cycle because of the transient nature of applied load and kinematic contact conditions. Ring geometry, surface topography, and lubricant rheology also play an important role. The aim is to attain full fluid film lubrication, thus reducing friction because of boundary interactions. Therefore, accurate prediction of lubricant film thickness and pressure distribution constitutes the first step in a proper analysis of piston ring-cylinder conjunction. The creation of a gap through elastic deformation is sought in order to inhibit asperity tip interactions. The generated contact pressures in the lubricant film are due to combined entraining motion and squeeze film effect. The integrated pressure distribution balances the elastic force due to ring tension and the applied combustion pressure acting behind the ring. The article highlights a detailed analysis, which forms the basis for its future expansion to include the study of mixed regime of lubrication, which may be prevalent in some real engines.

“…The elastic pressure around the ring circumference is not uniform (Okamoto and Sakai, 2001). It is maximum at point 90 • from the free end.…”

Section: Ring Bore Conformabilitymentioning

confidence: 93%

“…Transient nature of axial, later and tilt motion of piston skirt not only reduces the chance of piston scuffing, but also helps in flexing the ring during simultaneous sealing and sliding motion (Balakrishnan and Rahnejat, 2005). The out-of-round bore shape is responsible for a non-uniform gap of conformed ring and is critical to gas blow by Abe and Suzuki (1995) and Okamoto and Sakai (2001). Although such contacts are mostly operated in hydrodynamic regime, the friction loss is more in mixed regime because of reduced film thickness due to elevated combustion gas pressure.…”

Section: Introductionmentioning

confidence: 99%

Thermal Modeling of Thin Lubricant Film Within Piston Compression Ring and Rough Cyliner Liner Conjuction

2020

Front. Mech. Eng.

This work is devoted to develop a transient thermo elastohydrodynamic model for thermal analysis of micro scale oil film with in piston compression ring-liner conjunction. In this paper, heat dissipation through piston to cylinder wall mainly considered via thin film of lubricant on convection and conduction mode. It also includes frictional heat generated due to ring liner co-action while balancing total heat of the engine system. Results presented in this paper show that frictional heating raises additional lubricant temperature of 90 • C. Such increase in temperature is one of the reasons for presence of further oil degradation in high pressure zone of engine cycle, which appears between 300 and 400 • crank location.