Experimental Evaluation of Automotive Timing Chain Drive Impact Noise

The impact resulting from the meshing phenomena between a chain and sprocket has long been recognized as a dominant noise source in automotive timing systems. The impact results from a velocity difference between the individual chain link and the sprocket at the meshing engagement point. The velocity difference produces a local impact whose magnitude varies with the engagement frequency and is dependent on system parameters such as pitch, mass, tension, load, geometric layout, and others. An integrated experimental and analytical modeling approach has been developed and used to examine general impact/noise characteristics of automotive type timing chain drive systems. The objective of the analysis is to provide a basis to perform comparative type evaluation between various system parameters and/or operating conditions (i.e., static chain tension, system layout). Analytical models capable of predicting the local chain/sprocket engagement impact intensity have been applied to examine typical automotive timing drive dynamics. The work presented in this paper will concentrate on the complementary testing of chain drive systems to better understand the effects of the system parameters on the impact and meshing noise phenomena from an experimental point of view. The experimental work is performed on a specially developed test stand and is used to examine the radiated sound produced by the meshing impact. The test stand and testing procedures are described along with typical data and its interpretation with respect to the chain drive system.