Investigation of the Influences of Thrust Loads Resulted by Helix Angle Directions of Planetary Gear Sets on Bearing Power Losses in Automotive Planetary Gear Trains

Abstract

In the recent automotive industries, automotive technologies for improving fuel efficiency have focused on the developments of reducing power losses in a transmission. As a well-developed and conventional power transmitting system, an automatic transmission is still widely used in many automotive vehicles. The automatic transmission is co-axially designed with several planetary gear sets and other mechanical parts. The co-axial arrangements and gear helix angles make the transmission necessarily include bearings for supporting loads and allowing relative rotations. In this study, the influences of thrust loads yielded by helix angle directions of planetary gear sets on bearing power losses are presented by performing the structural and power loss analysis. Bearing power losses consist of mechanical and spin power losses. For calculating thrust loads and bearing rotations, a complete transmission model is constructed by using an example structure, and structural analysis is performed for the combinations of helix angle directions of the gear sets. Finally, bearing power losses are computed by using the bearing power loss model, and the results of the entire combinations of helix angle directions are discussed.

Research on the calculation and evaluation method of transmission efficiency of noncircular planetary gear

“…Željko and Angel [10] analyzed the mechanical and dimensional characteristics of a dual load planetary gear system under negative transmission ratios, and obtained all possible combinations of ideal torque ratios. Sik [11] studied the effect of thrust load in the spiral angle direction of planetary gear systems on the power loss of automotive planetary gear system bearings, and calculated the power loss of bearings and the combination of spiral angle directions. It is obvious that the analysis of power balance, load distribution, and efficiency loss in the above-mentioned literature is mainly based on measuring torque or other parameters.…”