Design of a fully integrated sensor system of a plain bearing

Abstract

Recent years revealed a notable trend for rolling bearings to be increasingly replaced by plain bearings for particular applications. A prominent example is the planetary stage in wind turbine gearboxes. The advantages of plain bearings are higher realizable power density due to smaller installation space compared to rolling bearings as well as the possibility of wear-free operation under ideal operational conditions. In real applications, however, plain bearings are subject to wear, for example due to start-stop processes, which lead to mixed friction conditions. Since the wear of plain bearings strongly depends on the operational conditions, monitoring is essential to detect inadmissible operating conditions. To avoid extra installation space and to achieve a minimal influence on the surrounding system, this work aims to integrate an energy-autarkic sensor system into the bearing volume to monitor the operational status of the plain bearing. To achieve autarky, the resulting data must be transmitted wirelessly and the external power supply must be eliminated. In this work, the software and hardware architecture of a sensor-integrating plain bearing prototype for monitoring the minimum oil gap height and the displacement angle of the shaft based on in-situ temperature measurements is presented. Furthermore, energy harvesting and energy saving measures are implemented and evaluated which intend to enable completely autarkic operation of the sensor integrating machine element in the future. A prototype of the sensor system is in turn used in-the-field to investigate required sampling rates and the spatial resolution of the temperature measurements.