Thermal analysis of gear transmission systems using experimental and finite element modelling techniques

Under the banner of a Brite Euram project 'INTRANS', (Mechanical Integrity for advanced Transmission systems) an investigation into gear cooling and power loss has been undertaken. The research described in the paper is divided into two parts. The first part comprises an experimental programme in which an Institute of Automotive Engineering (IAE) gear test machine is utilised to measure temperatures using thermocouples via slip-rings, and an infrared camera. The second part is concerned with developing a thermal model of a gear contact. Using a computerised data acquisition system, experimental temperature measurements included the gear tooth surface (infra-red camera), gear tooth (thermocouples located below the working surface), gear body and the shaft temperature. Other static measurements comprised the test chamber environment and body temperatures for different oil inlet temperatures, and now rates over a range of operating loads and speeds. The principal objective of the experimental phase was to generate temperature data to assist in the development of a thermal model to predict gear tooth temperatures by using the finite element method. Heat transfer coefficients for the gear teeth and the disc sides were determined in conjunction with the heat flux generated at the tooth contact. Initially, a model of a single gear was generated but in order to reduce computational time this was subsequently modified to that of a single gear tooth segment. The model development and results are presented, including comparisons with the experimental results.