The torsional stiffness of involute spur planetary gears

This paper presents the results of torsional stiffness analysis of involute spur planetary gears in mesh using finite element methods. A planetary gear model with 3 planet gears and its subsystem models have been developed to study the relationship between the overall torsional stiffness and the subsystem torsional stiffness. The subsystem models include one isolated sun-planet-ring pair, one isolated sun-planet external pair and one isolated planet-ring internal pair. A strategy utilising a small preload step via a weak spring was first applied to eliminate the gap between the teeth and then different torque levels were applied to calculate the transmission error due to the resulting elastic deformations. This calculation was repeated at multiple positions covering two tooth mesh cycles in the overall and subsystem models. The theoretical gear contact position was determined using an ANSYS APDL program and the gear rolling range was digitized into equidistant rolling angles. The sun-planet torsional stiffness variation has been shown to dominate the combined torsional stiffness and, based on the subsystem torsional stiffness, an analytical method for predicting the overall torsional stiffness is presented

Gearbox Reliability Collaborative: Test and Model Investigation of Sun Orbit and Planet Load Share in a Wind Turbine Gearbox

This paper analyzes experimental measurement of the sun gear orbit in dynamometer testing and describes its relation to the other measured responses of the planetary stage. The relation of the sun orbit to component runout, component flexibility, gear coupling alignment, planet load share, and planet position error will be investigated. Equations describing the orbit of the sun gear in the test cases are derived. Rigid and flexible multibody models of the full gearbox are investigated and compared to sun and planet measurements. This paper shows that the sun gear's path may be influenced by gear coupling responses and gearbox structural flexibilities