Triboelectric based high-precision self-powering cage skidding sensor and application on main bearing of jet engine

Monitoring the dynamic behavior of rolling bearings is important to ensure the reliability of rotating machinery. In this study, a novel, high-precision, self-powering triboelectric bearing skidding sensor (HP-TEBSS) is developed for the real-time monitoring of bearing skidding degree and cage stability characteristics. A floating sweeping, freestanding mode is adopted to ensure long-term reliability, and the HP-TEBSS does not affect the bearing structure and dynamic behavior. The proposed sensor consists of an interdigital electrode plate, a dielectric ring with a protruding surface, and a fixed ring. The dielectric ring, which is pasted to the side surface of the integral copper cage, rotates synchronously with the cage and sweeps to the electrode plate. The HP-TEBSS generates Ne (number of electrode finger pairs) times of instantaneous cage speed information than that of commercial sensor, and the deviation between these two sensors is less than 1%. This shows the advanced realtime performance and monitoring accuracy of the proposed sensor. Experiments are conducted under variable working conditions with different structural parameters to optimize the sensor output performance. The selfpowering and 50 h durability capabilities of the HP-TEBSS are demonstrated. Bearing skidding and cage rotation stability under variable spindle rotation speeds and bearing axial loads are systematically evaluated. It was found that in the light-load range, the skidding degree showed an increasing trend as the speed increased, whereas it showed the opposite trend under the heavy-load range. The monitoring results of cage speed fluctuations, which indicate running stability, provide recommendations for preventing bearing operation in the vulnerable range. Furthermore, the proposed bearing dynamic model is validated using the HP-TEBSS test results to demonstrate the wide applicability, high portability, and high-speed performance of the HP-TEBSS prototype. The application of the HP-TEBSS on a high-speed jet engine test bench is analyzed. It is found that cage skidding shows a certain degree of hysteresis in the deceleration stage, as compared to the acceleration stage, owing to cage inertia. Finally, theoretical and experimental aspects of the presented self-powering multifunctional HPTEBSS that can be applied in the smart rolling bearing field are presented.