Title: Microgeometrical tooth profile modification influencing efficiency of planetary hub gears

Authors: Ehsan Fatourehchi; Mahdi Mohammadpour; Paul D. King; Homer Rahnejat; Gareth Trimmer; Alan Williams

Addresses: Wolfson School of Mechanical Engineering, Loughborough University, LE113TU, UK ' Wolfson School of Mechanical Engineering, Loughborough University, LE113TU, UK ' Wolfson School of Mechanical Engineering, Loughborough University, LE113TU, UK ' Wolfson School of Mechanical Engineering, Loughborough University, LE113TU, UK ' JCB Transmission, Wrexham Industrial Estate, Wrexham, UK ' JCB Transmission, Wrexham Industrial Estate, Wrexham, UK

Abstract: Planetary hub systems offer desired speed and torque variation with a lighter, compact and coaxial construction than the traditional gear trains. Generated friction between the mating teeth flanks of vehicular planetary hubs under varying load-speed conditions is one of the main sources of power loss. Modification of gear tooth geometry as well as controlling the contacting surface topography is the remedial action. The paper studies the effect of tooth crowning and tip relief upon system efficiency. It includes an analytical elastohydrodynamic analysis of elliptical point contact of crowned spur gear teeth. The analysis also includes the effect of direct contact of asperities on the opposing meshing surfaces. Tooth contact analysis (TCA) is used to obtain the contact footprint shape as well as contact kinematics and load distribution. A parametric study is carried out to observe the effect of gear teeth crowning and tip relief with different levels of surface finish upon the planetary hubs' power loss.

Keywords: transmission efficiency; gear tooth modification; planetary wheel hub system; surface finish.

DOI: 10.1504/IJPT.2018.090374

International Journal of Powertrains, 2018 Vol.7 No.1/2/3, pp.162 - 179

Received: 06 Feb 2017
Accepted: 24 Jul 2017
Published online: 13 Mar 2018 *

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