On the behaviour of n-planets planetary gear sets influenced by geometrical design factors

Abstract

This work presents a study focused on the behaviour of low-speed planetary gear sets with 3 to 7 equally spaced planets affected by their inherent geometrical characteristics. On the one hand, this work identifies the conditions that make the transmission act as fixed, even including floatability in the sun gear, due to their inherent geometrical factors in transmissions with an even number of planets. On the other hand, this work extends the criteria employed to classify the kinds of planetary gearboxes according to their geometry, including the order of the sequence in a sequentially phased transmission. A new expression is proposed in order to take this order into account. Then, several different transmissions are modelled covering the possible configurations. To observe the impact that these aspects have in the transmission´s behaviour the load sharing ratio and the orbits described by the sun gear are extracted. These results confirm the importance of the mentioned sequence order in the behaviour of these transmissions.