Integration of Printed Sensors in Plain Engine Bearings

The integration of sensors in engine components has been a long-standing wish of engine manufacturers and researchers. Conventional probes are particularly difficult to mount in moving engine parts and require time-intensive and costly preparation, while often still not reaching the site of interest close enough. The advances recently made in the field of printed electronics enable new possibilities for sensor integration that previously were not possible. Particularly, crankshaft engine bearings are an interesting component to apply those new sensors to. An important enabling factor for the successful sensor integration has been the increasing market penetration of polymer overlays for crankshaft bearings. The driving force behind this development was the pressure from legislation to reduce CO2 emissions, which in turn brought about new technologies such as start-stop and mild hybrids. Engine components now have to operate in much more aggressive environments, which in many cases only polymer overlays withstand. The unique application process of those coatings together with their material properties, such as robustness and non-conductivity, now allow embedding of electronic components right at the running surface of the bearings. This paper details the development of a printed sensor that has been integrated into the bearing polymer overlay coating. Various results from respective rig testing of the sensor feedback throughout different load and speed conditions during operation are reported.