OPTIMUM DESIGN OF A 2K-H INVOLUTE PLANETARY DRIVE WITH TWO CENTRAL INTERNAL GEARS

OPTIMUM DESIGN OF A 2K-H INVOLUTE PLANETARY DRIVE WITH TWO CENTRAL INTERNAL GEARS

The optimum design for involute K-H-V involute planetary drives with a small teeth number difference (PDSTND) has been studied. This work is devoted to the optimum design for 2K-H involute planetary drives with two central internal gears. The 2K-H PDSTND with two central internal gears allows several matching numbers of teeth with high speed reduction ratio (SRR) and smaller sizes at the cost of the mechanical efficiency compared to the K-H-V PDSTND. Furthermore, some of matching numbers of teeth have three, four or five teeth number differences (TND), which can alleviate design difficulties such as the tip interference and obtain the better working pressure angles at the cost of the contact ratio compared to the K-H-V PDSTND. The selection of the appropriate TND which has a great influence on the design results is discussed. This study shows an optimum design for a 2K-H involute PDSTND with an SRR equal to 990 or 2002 capable of obtaining a mechanical efficiency of 85.40% or 75.18%, with contact ratios greater than 1.3 and working pressure angles smaller than 27 degrees. Sensitivity analyses of the contact ratio and mechanical efficiency for the five design variables are implemented.