Theoretical and Experimental Investigation of the Thermal Stability of a Cycloid Speed Reducer

High-precision drives are essential for ensuring accuracy and repeatability in positioning systems within robotics and industrial automation. Among these, cycloidal reducers are widely utilized due to their ability to deliver a high transmission ratio alongside high power density. However, compact designs often face challenges such as elevated operating temperatures caused by limited heat dissipation areas, making it crucial to assess thermal stability within the design process. While engineering practice typically determines the thermal stability of gear drives using ISO/TR 14179-2:2001, no specific methodologies have yet been developed for cycloidal reducers. To address this gap, this paper presents a novel mathematical model fine-tuned to quantify power dissipation and predict lubricant stabilization temperatures under varying operating conditions. The model employs a global energy balance approach, correlating total power losses with the heat dissipated from the reducer to the environment. Moreover, in this study, an experimental campaign was carried out to monitor the thermal behaviour of a cycloidal reducer under various operating conditions in terms of speed and transmitted torque. This was achieved through the analysis of images collected with an infrared thermal camera, both during the transient phase and under steady-state thermal conditions. The results demonstrate good alignment with experimental findings, although further refinements are required to develop specialized tools for cycloidal drives. Additional contributions of the present paper include the understanding of the time required to achieve thermal stability, as well as insights into heat generation and propagation. Beyond advancing scientific knowledge, this work also provides valuable practical guidance for engineering applications.