Thermal stability of lubricants in cycloidal reducers

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Milan Vasić
Mirko Blagojević
Mircea V. Dragoi


There is intensive rolling and sliding between the meshing elements of a cycloidal reducer, whereby a significant amount of mechanical energy is converted into heat and absorbed by the lubricant. In order to stabilize the temperature of the lubricant, it is necessary to achieve thermal equilibrium, i.e. the amount of heat dissipated should equal the amount of heat generated. A complex task of determining the equilibrium temperature of a lubricant generally involves theoretical analysis, numerical calculation, computational simulations and experimental testing. The aim of this paper is to develop a model to predict the amount of heat dissipated from the outer surface of the housing as well as the equilibrium temperature of the lubricant. The model is based on the basic laws of thermodynamics, while the computational simulation is performed for an actual cycloidal reducer in the Matlab software package. The simulation results show changes in the equilibrium temperature in relation to: the coefficient of heat transfer from the lubricant to the inner wall of the housing, ambient air velocity, wall thickness and housing material.

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