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In this paper we describe the application of optimization techniques to the design of valvetrains in high revving internal combustion engines. The methods presented are based on parameter optimization [1] and the minimum principle by Pontrjagin [2] and will be applied to cam lobe and valve spring optimization, aiming at reducing oscillation amplitudes and improving control of the valvetrain over a broad speed range. To put the task of optimization into context the engineering requirements for valvetrains and methods to allow their computer based analysis are described. Furthermore principle considerations for valve event curve generation and parametrization, and on optimization techniques are discussed. Based on these fundamentals, optimization aims and constraints are formulated. Furthermore different examples of the application of automated optimization are presented in the area of cam profile optimization and valve spring optimization.

In this paper, models for valve spring dynamics are presented which cover: (i) A simple modal approach for linear valve springs. (ii) A detailed discrete non-linear model which is able to predict all important effects in progressive valve springs, including clash of interfering coils. (iii) A new approach to handle a modal model of progressive springs in the frequency domain. On the testing side, the development of specially designed transducers to back up the theoretical results is presented and the measured results are compared to the results from the different models.