Analysis of the potential for analog and digital signal transmission via axial and radial rolling element bearings as signal transmission elements for rotating shafts

Abstract In the context of advancing digitalization, the focus is on data acquisition using suitable sensors. Therefore, data acquisition and the required sensor technology should be located within the system to measure as close to the process as possible. With rotating systems in mechanical engineering, the integration of sensors on rotating elements poses a challenge, because the recorded data must be transferred from the rotating element to the evaluation unit. One option for this is electrical contacts like slip rings. However, these have the disadvantage that additional elements and installation space are required in the system. In this article, the technical possibilities of using conventional rolling bearings as signal transmission elements are investigated. For this purpose, analog and digital signals are transmitted via radial and axial rolling bearings under different operating conditions. The transmission quality is quantitatively analyzed. Analog voltage signals and digital signals modulated in various ways are used as test signals. It can be seen that the capacitive behavior of the rolling bearings causes a damping signal transmission behavior for analog signals. Axial and radial rolling bearings differ in their resulting damping of the transmitted electrical signals. The carrier frequency of the signals, the oil temperature and the bearing loads have a significant influence on the damping behavior. Robust signal transmission is observed with digital signals. Frequency shift keying and phase shift keying modulations exhibit the lowest transmission errors. Amplitude shift keying can only be used with restrictions due to the pronounced damping behavior of the rolling bearings. Overall, there is a pronounced potential for the transmission of analog and, above all, digital sensor signals via rolling bearings as a transmission element between rotating and stationary systems. In addition to the potential, the work also shows new research directions for further investigations.