A Comprehensive Drive Chain Model Applicable to Valvetrain Systems 2005-01-1650
A model of roller chain and sprocket dynamics was developed, aimed at analyses of dynamic effects of chain drive systems in automotive valvetrains. Each chain link is modeled as a rigid body with planar motion, with three degrees of freedom and connected to adjacent links by means of a springs and dampers. The kinematics of roller-sprocket contacts are modeled in full detail. Sprocket motions in the chain's plane, resulting from torsional and bending motions of attached camshafts are also taken into account. One or two-sided guides can be treated as well as stationary, sliding or pivoting tensioners operated mechanically or hydraulically. The model also takes into account the contact kinematics between chain link rollers and guides or tensioners, allowing for guides/tensioners of arbitrary shape, or simpler (flat and circular) geometries.
The model is first applied to study the chain drive and valvetrain of a 1-cylinder motorcycle engine. The chain drive (roller chain, guide and tensioner) is modeled as well as the entire connected valvetrain, in order to account for important torsional and other dynamic interactions between the two. Computational predictions are compared to experimental data. The model captures the effects of the dynamics of the chain drive on valvetrain behavior both qualitatively and quantitatively. The same methodology was also used to model and simulate a more complex chain drive system for an automotive V-engine, in which three interconnected chains drive the intake and exhaust camshafts. Predictions were compared to test data and good correlation was again observed between computational and experimental data.