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Engine running in has significant impact on tribological performance of the engine. This study investigated topographical changes of engine bores during running in experimentally and theoretically. Engine bores with various height distributions were generated by changing honing parameters. Engine running-in tests were conducted to observe changes of surface topography on engine bores. Surface height distributions were described by the Johnson translatory system. A running-in wear model was used to predict the progress of surface topography during engine running in. Comparisons between experimental and theoretical results show that the model used in this study can describe the topographical changes of running-in wear for surfaces with different height distributions.

A 3-D surface topography measurement system was constructed for the surface characterization of an area. This system consists of a personal computer, a microdisplacement stage and a surface profilometer. The microdisplacement system moves the samples laterally for successive traces and ensures the parallelism of each surface profile. The personal computer coordinates the stage movement and surface profile measurements, provides large data storage, and allows rapid data manipulation. This system provides an easy, effective way to characterize a surface, together with versatile displays to observe and record surface topography. It has been used for wear-scar characterization and paint-defect detection. A relocation fixture was incorporated with the 3-D surface-measurement system to provide a powerful tool to observe progressive changes in the surface topography during tribological tests.

A comprehensive computer package, FLARE, has been developed for carrying out Friction and Lubrication Analysis of Reciprocating Engines. FLARE considers four major lubricated components in an automotive engine -- piston skirt, piston rings, bearings, and valve train. Hydrodynamic, mixed, and boundary lubrication models are used, as appropriate, to model the lubrication phenomena. All the analytical models are based on solution of governing equations. Three levels of analyses with varying degrees of detail have been developed. Availability of different levels provides the flexibility of matching the complexity and accuracy of the analysis with the objective of the analysis. An empirical engine friction model, which is based on experimental data, is also available. Many user-friendly features are built into the FLARE system to make it easier to use for design engineers. This paper gives a brief overview of all the analysis sub-models incorporated into FLARE.

Piston-ring friction accounts for a substantial portion of engine friction. The performance of piston rings also affects many aspects of engine performance such as oil consumption, blowby and wear. Because of the complexity of the piston-ring and cylinder-bore interface, the comprehensiveness of piston ring analysis has historically lagged behind that of other engine components. This paper describes a recently developed lubrication analysis of the piston-ring pack. The new analysis improves upon existing analyses in several areas, and it includes two models. The simpler model includes only fully flooded lubrication analysis. The more comprehensive model considers the effects of lubricant starvation and includes the lubricant transport on the cylinder bore. Applications of these analytical methods to evaluate the effects of design parameters are also presented.