Abstract
The optimization method of profile-shift coefficients for the design of conventional mechanical paradox planetary gear drives of maximum efficiency is proposed and described. The objective function of all of the four profile-shift coefficients is converted to a function of only two profile-shift coefficients. Drawing the objective function on a plane with the coordinates of the two profile-shift coefficients and connecting the points with the same value gives a map of contour lines ; the ridge which gives the maximum efficiency becomes almost a straight line on the plane. Also, the constraint domains, which are determined from the constraint conditions such as contact ratio and undercut, are located on the straight ridge ; the lower limit of the constraint domains also becomes a straight line. The optimum profile-shift coefficients are investigated by increasing one of the profile-shift coefficients step by step from the value determined by the intersection of the two straight lines. Thus the optimum profile-shift coefficients have been determined for various conventional mechanical paradox planetary gears ; the obtained maximum efficiencies are almost 78% for those gear drives.
