Hydrodynamic Lubrication of Piston Skirts

Proceedings of the Institution of Mechanical Engineers, Part J:

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.

Section: Introductionmentioning

confidence: 99%

Tribology of compression ring-to-cylinder contact at reversal

Mishra

Balakrishnan

Proceedings of the Institution of Mechanical Engineers, Part J:

2008

“…A translational joint is employed to constrain the motion of the piston to pure translation along the cylinder bore. This precludes its tilting motion, which results in piston slapping action, and reduces the computation burden and the need for a step-by-step evaluation of contact reaction under elastohydrodynamic conditions (see references [58] and [66]). The connecting rods are connected to the piston by revolute joints, and to their respective crankpins by an in-line joint primitive.…”

Section: Simulation Of Multicylinder Internal Combustion Enginesmentioning

confidence: 99%

“…An analysis of this motion is provided in reference [58] with the detailed contact conditions described by Knoll and Peeken [66]. Another source of non-linearity is the jump phenomenon in the dynamic behaviour of supporting journal bearings, where under unchanged load and speed conditions the vibrating crankshaft can jump from one seemingly stable position to another.…”

Section: Introductionmentioning

confidence: 99%

Multi-body dynamics: Historical evolution and application

Proceedings of the Institution of Mechanical Engineers, Part C:

2000

The historical developments in the discipline of engineering dynamics are brie¯y reviewed, with attention paid to the formulation and solution of the dynamic behaviour of multi-body systems. It is shown that the dynamic characteristics of practical multi-body systems are dependent upon the interactions of many physical phenomena that can induce, restrain or constrain motion of parts. The long process of understanding and formulating the physics of multi-body motions, in some cases with pioneering contributions centuries old, together with continual re®nements in numerical techniques and enhanced computing power has resulted in the solution of quite complex and practical engineering problems. Linking the historical developments to the fundamental physical phenomena and their interactions, the paper presents solutions to two complex multi-body dynamic problems. The practical implications of the approach in design of these systems are highlighted.

“…Tribological considerations for piston-cylinder interactions have largely been ignored in most engine models. This aspect of investigation has always been carried out in specific studies with very long computation times, assuming hydrodynamic or elastohydrodynamic conditions [20,21]. It is, however, an important feature of engine dynamics and representative models of this should be incorporated in any multi-physics analysis.…”

Section: Introductionmentioning

confidence: 99%

A multi-physics multi-scale approach in engine design analysis

Perera

Theodossiades

Proceedings of the Institution of Mechanical Engineers, Part K:

2007

• This is an article from the journal, Proceedings of the Institution of Me- Abstract: Vibration behaviour of an internal combustion engine depends on rigid body inertial dynamics, structural modal characteristics of its elastic members, tribological behaviour of loadbearing contacts, and piston-cylinder interactions. Therefore, it is essential to use a multi-physics approach that addresses all these physical properties in a single integrative model as presented in this paper. This approach can be regarded as holistic and a good aid for detailed design. Particular attention is paid to the critical elements in the system, such as load-bearing conjunctions (crankshaft main bearings) and piston-cylinder wall interactions. Another important feature is the integrated analysis across the physics of motion from microscale fluid film formation to submillimetre structural deformations and onto large displacements of inertial members. In order to succeed in predictions within sensible industrial time scales, analytical methods have been used as far as possible rather than numerical approaches. Model predictions show good agreement with fired engine test data.