New Methods in VALVE CAM DESIGN

BY relatively simple mathematics, it is possible to include the effects of mass, flexibility, valve-spring force, and gas pressure in designing valve cams for automobile or aircraft engines.

First, a curve of ideal valve motion having suitable lift area and minimum acceleration properties is specified. Then, with the valve assumed to be executing this motion at a chosen speed, the sum of the inertia, gas pressure, and valve-spring forces can be computed at any point in the cycle. The driving force to overcome these resistances is created by compressing the valve linkage.

The amount of deflection needed at any time can be found. These deflections are added to the valve motion to find the correct cam lift.