A multi-purpose valvetrain analysis tool has been developed, which is aimed at addressing all design issues arising in various stages of valvetrain development. Its capabilities include polynomial cam design, valvetrain mechanism kinematics, quasi-dynamic analysis, spring design/selection, multi-body elastic analysis of a single valvetrain with cam-follower and bearing tribology, and multi-valvetrain dynamics with camshaft torsional vibrations.
The basic architecture of this tool is object-oriented. Its underlying basis is a library of cam design methods, kinematics operators, and dynamics/hydraulics/tribology primitives (masses, dampers, springs, etc.). On top of this basic system lies a higher-level library of valvetrain
compound
objects, which are pre-programmed sub-assemblies of valvetrain components built from the primitives. These high level objects minimize modeling effort and may be mixed with primitives, allowing construction of models for virtually any valvetrain. As a result, the methodology offers both the simplicity and ease of use of a dedicated valvetrain analysis tool, but also the flexibility of general-purpose multi-body dynamics software. Additional versatility stems from the integration of the cam design, kinematics and dynamics functions into a single tool
and
further coupling to an engine performance analysis tool as well as general-purpose system dynamics/control software.
This paper describes the methodology and its capabilities in general and selected key submodels, specifically those for valve springs, hydraulic lash adjuster, cam-follower tribology and bearing oil films in more detail. Comparisons of predictions to experimental data are also presented, as well as examples of applications.
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