Abstract
This paper presents a practical computer-aided method called the ‘grid and star search technique’ for determining the values of adjustable design parameters. The objective is to find that set of values necessary to obtain a solution as nearly optimum as possible. The technique is a systematic search for the best set of parameters in a bounded region of possible answers. A ‘performance index’ must be defined to determine the merit of the solution after each iterative step in the procedure. The design of a spool type hydraulic relief valve is used as a practical example. The adjustable parameters are spring rate, metering orifice size, damping orifice area, and the volume of oil trapped between the pressure-sensing end of the spool and the damping orifice. The driving function is a step input of rated flow, and the optimum response is one with zero pressure overshoot. When the valve was made and tested, comparison between actual and predicted response was satisfactory.
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