Vibration behaviour of stepped pinion type planetary gears

Abstract

It is well known that the characteristics of exiting force of planetary gear mesh are varied with gear mesh phase between pinions in single pinion type planetary gear set and that the sideband phenomenon occurs in the sequentially phased planetary gear set. This sideband phenomenon is one in which the (Z-1) or (Z+1) order component level is higher than the mesh order (Z) component level. The notation (Z-1) or (Z+1) means the mesh order (Z) minus or plus one carrier revolution. In this study, the relationship between gear mesh phase and vibration behavior is investigated in the stepped pinion type planetary gear set which has two mesh order component and is operated at wide frequency range. The formulae of mesh force of 6 degrees of freedom acting in sun gear, carrier and ring gear respectively are derived for stepped type planetary gear set. From the experimental and calculated results, the same side band phenomena were also observed in the stepped type planetary set. By taking into account the side band order component of gear mesh, it was revealed that the influence of gear mesh phase on the characteristics of unit case vibration is varied by frequency range. It is considered that the dominant direction component of exiting force for the case vibration of applied unit moves from transverse direction at low- frequency range to rotation direction at high-frequency range.