Optimal Design of High Speed Valve Train Systems

One of the major tendencies in engine design is to increase operating speed. In order to increase engine speed, the importance of valve train design and dynamic behavior becomes crucial. Optimal design of the system can result in improved dynamic characteristics.

A valve train design methodology is developed in this paper that incorporates an efficient, accurate dynamic system model in the design procedure. The cam profile is synthesized using eight polynomial equations cast in terms of nine nondimensional parameters which are to be optimized. The objective function is cast so as to minimize the residual vibration amplitude of the valve. Several constraints are included such as event duration, maximum tappet lift, maximum tappet velocity, and maximum tappet acceleration..

An adaptive random search technique is used to seek global optimal solutions to the problem. The design methodology was applied to a typical NASCAR valve train and significant increases in engine speed were obtained.