Impact dynamics of chain drive systems

Meshing noise has been identified to be the most significant noise source in a chain drive system. The two major mechanisms for creating meshing noise are the polygonal action and the chain/sprocket impact. Experimental studies show that the chain drive dynamic response is not just a local problem at the chain/sprocket interface. It is related to the characteristics of the total system. The sprocket motion, the chain longitudinal and transverse vibrations, the polygonal action, and the chain/sprocket impact dynamics are all interrelated. An integrated model has yet to be developed and validated to describe this complex mechanical system accurately.; This thesis presents a comprehensive analysis of the chain/sprocket impact dynamics with analytical models and experimental investigations. The analytical models include an axially moving chain dynamic model and a chain drive system dynamic model.; The first model integrates the local meshing dynamics with the global vibration of the chain. The fundamental characteristics of moving chain interacting with local impacts are investigated. It was found that the impact intensity is significantly affected by the vibration characteristics and response of the moving chain, and vice versa. The classic quasi-static approach will create errors in predicting the impulse magnitude and system response. Meshing frequencies that will cause maximum and minimum impulses are analytically predicted.; The second model integrates the local impacts with the chain span motion and sprocket motion. The coupled mechanism among chain spans, sprockets and meshing impact is discussed. The coupling effects between sprocket and longitudinal chain span under meshing impacts are investigated. It was found that these coupling effects decrease with increasing the sprocket inertia and the chain longitudinal stiffness. The difference between these analytical models are compared. The guidelines for using these models are discussed.; Experimental investigations are presented to verify the analytical predictions. Instrumentation techniques and data acquisition system are introduced. This fundamental investigation provides new insight to chain drive impact dynamics and noise problems.