Design of a variable radius piston profile generating algorithm

One of the main sources of efficiency loss in heat engines is the inability of a sinusoidally displaced piston engines to approximate the ideal heat volumetric cycles the engines require. While attempts have been made to address this issue in the past, recent developments in Stirling engine technology utilizing rolling diaphragm seals on the cylinders has offered an opportunity to greatly increase the correlation between an engines volume-time profile to the ideal profile. By changing the radius of the piston used to drive the rolling diaphragm connection over its length, the piston can effectively be used as a " transfer function " translating the sinusoidal displacement of the crankshaft into a near ideal heat cycle volumetric displacement. This work presents a methodology for determining the ideal shape of such a piston, and a model used to most effectively match a desired input linear displacement profile with output volumetric displacement profile, without compromising the operating conditions required to maintain the diaphragm itself.