Gear transmission errors are influenced by temperature especially in the aerospace field. A model is proposed to investigate the influence of temperature on cylindrical gear transmission errors based on the thermal network (TETN). The gear temperature field distribution model is established based on the thermal network method, and gear thermal deformation can be calculated along the gear meshing line. Regarding the gear single-flank rolling process, the variation of gear transmission errors under temperature is determined. In numerical calculations in MATLAB, the variation of gear transmission errors at 100°C compared to 20°C is –4.20 μm, which decreases almost linearly while the thermal expansion coefficient of the gear material increases. The simulation of the gear transmission errors variation of temperatures using the finite element method (FEM) were carried out in Workbench software under Ansys and the average difference of the TETN model results between calculations and FEM for different temperatures was 0.24 μm. Experiments were carried out on the gear tester in temperatures ranging from 0°C to 100°C, the TETN model results in calculations were compared with the results of the tester, and the average difference was –1.15 μm. The results show that the proposed TETN can be used as an algorithm to determine the variation of gear transmission errors under the influence of temperature.

The purpose of this paper is to develop a dynamic thermal model of a permanent magnet excited synchronous motor (PMSM). The model estimates the temperature at specific points of the machine during operation. The model is implemented using thermal network theory, whose parameters are determined by means of analytical approaches. Usually thermal models are initialized and referenced to room temperature. However, this can lead to incorrect results, if the simulations are performed when the electrical machine operates under “warm” conditions. An approach is developed and discussed in this paper, which captures the model in critical states of the machine. The model gives feedback by online measured quantities to estimate the initial temperature. The paper provides an extended dynamic thermal model, which leads to a more accurate and more efficient thermal estimation.

The paper presents a model for calculations of the temperature field in electric mine motors with a water cooled frame. That model was worked out with use of modified and improved thermal networks developed by the author for determining the temperature distributions in different types of ac machines. Thermal calculations for a selected type of 400 kW mining motor were performed with use of an original computer program. Their results were compared with those obtained from measurements. On the basis of the verified simulation results there was determined the influence of value changes of parameters characterising the work environment condition (ambient temperature, inlet temperature and cooling water discharge, degree of covering the casing with coal dust) on the mining motor thermal state.