A frequency domain approach to the analysis and optimization valve spring dynamics
2013-02-13T12:05:02Z (GMT) by
In this thesis a method is derived and presented, for the efficient analysis of the steady state response of dynamic systems with time variant propenies. The method is especially attractive for the simulation of the steady state response of lightly damped systems with low numbers of degree of freedom which are forced by a periodic excitation. A major feature of the method is that the system non-linearities can be successfully modelled as time variant propenies. An ideal application for this approach is the calculation of the dynamic response of a modal model for progressive valve springs in the frequency domain. The solution method is explained and derived using this example. The differences, drawbacks, and advantages are assessed by comparison with both a linear modal model and a discrete time-domain model; correlation with actual measurement is also shown. The extreme efficiency of the method allows its application in a more general study of the dynamic propenies of valve springs. This analysis is initially discussed and examined using statistical methods. Then the frequency domain solution method is employed to perform an automatic optimization of the spring frequency characteristic for a 16 valve prototype engine application. The spring design obtained from this study has been manufactured and the resulting hardware is discussed. The measured response of this hardware is compared with simulation results for the same configuration, verifying the fmdings from the statistical investigation and the optimization. Finally open issues and further envisaged work in the area of damping mechanisms in valve springs and manufacturing issues are diScussed and an approach for the next steps to take is outlined.