Thermal design of portable power tools with combustion engines and electric motors

Authors

Dr.-Ing. Silke Kaminski, Dr.-Ing. Gordon Groskopf, Andreas STIHL AG & Co. KG

Year

2019

Summary

The goal of thermal design and optimization – whether for portable power tools with combustion or electric motors – is the thermal protection of the machine to prevent overheating and subsequent damages. To ultimately reach a reliable solution for all requirements, both cases involve diverse restrictions in the design process. With increasingly sophisticated machines that combine the highest performance, minimal weight and compact assembly space, the demands on cooling design continue to grow. In order to meet these demands, it is essential to integrate the respective cooling requirements into the very early phases of product development in machine design. For this purpose, the „coupled-cooling calculation“ method is employed following dimensioning tools. This method is a simulation of the airflow and the heat flow in the virtual machine. The „coupled-cooling calculation“ method makes it possible to understand as well as to specifically influence the physics of the heat balance, even before the first real prototypes are formed. A team from Design, Simulation and Testing collaborate closely to develop optimization measures. The findings from the calculations are integrated into the prototype machines which then ideally – from a thermal perspective – are functional without any further measures. The calculated temperatures are also used in thermal mechanical fatigue analyses, so as to virtually ensure the service life of the machines.

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