Study On Nonlinear Dynamics Of Valve System Of Internal Combustion Engine

This dissertationis based on the requirement of design of modern ICE and theconcrete engineering problems of valve system. Nonlinear vibration theory and themethod of dynamical analysis are applied and developed originally in the research ofnonlinear dynamics of valve system. Characteristics of multi-resonance of valvesystem resulted from physical parameters are investigated both in theory andexperiment. The relations between multi-resonance, longitudinal-torsionvibration andsome physical parameters are revealed. Through this dissertation, some fundamentalsare set up with the aim to optimize valve system design. The contents and major results of this dissertationare as follows: The condition and method of nonlinear dynamics of valve system are brieflyreviewed, and progresses in this field are concluded. Some basic aspects of nonlinearvibration theory, including solution method commonly used and some properties ofsolutions are emphasized. Investigating valve system with OHV, the kinematical and dynamical responseof continuous and discrete model are analyzed using vibration theory. The theoreticalmethod calculating dynamic response of valve spring and load on valve are presented,which is helpful for engineering design of valve system. The effect of initialconditions on dynamical Characteristics of valve spring is discussed. The differentialequations of motion of valve spring are set up using discrete model, and clash forcedue to neighboring coils contacting each other is analyzing in detail. On the basis ofthis computer simulation is conducted and coincidence is achieved. Nonlinear responses of double-resonance and triple-resonance of valve springare investigated with 1st order natural frequency to 2nd satisfying 1:2 internalresonance relationship. The study shows complicated laws of multi-resonance. Thedynamic bifurcation responses are analyzed under several different resonanceconditions, and the relationship between the response and the magnitude of excitationis exhibited. According to the theoretically analytical results, stiffness and damping ofvalve spring are principally physical parameters impacting the structure of bifurcationresponses, supplying a direction for vibration active control. The theoretical results oftwo kinds of double-resonance verified by experiment. A theoretical investigation of the coupled extensional-torsional vibration ofvalve spring is presented. The law between these two vibration mode coupling isrevealed. This concept of coupled vibration analysis is helpful to detecting vibratorylaws of valve system.