Research On The Micro Wideband Piezoelectric Energy Harvester Applied In The Engine Vibration Monitoring

The engine condition monitoring method and fault diagnosis technique based on the basic characteristics of engine vibration signal is a significant mean of enhancing the operation reliability of the engine and reducing the blindness of the maintenance and repair work. In order to extract more complete and accurate operation information and fault signal of the engine, a plenty of wireless acceleration nodes are usually employed and installed on the various positions of one each engine. However, it is an inevitable and key issue to find the non-battery power supply way for the wireless acceleration nodes to further improve the application of the engine condition monitoring method and fault diagnosis technique. Accordingly, aiming at the multi-sources wideband and complex vibration characteristics of the engine,the paper focuses on the bandwidth expansion technologies of the piezoelectric energy harvesters and provides a self-powered solving plan for the wireless acceleration nodes.Firstly, the necessity and possibility of applying the vibration energy harvesting technique to the practical engine condition monitoring and fault diagnosing systems are analyzed in the paper. The existing bandwidth expanding technologies of the piezoelectric energy harvesters are summarized. Besides, individual advantages and disadvantages and suitable environment are listed. Secondly, taking the automotive engine as the monitoring content, the vibration signals on the cylinder head of the 2HO engine of Chevrolet Epica in normal and no-load running conditions are tested and the characteristics of the engine vibration sources and corresponding vibration signals are illustrated. Based on that, taking into account both power output and frequency bandwidth, the micro wideband piezoelectric vibration energy harvester applicable to the tested engine vibration environment is designed. The distributed parameter model of the designed micro wideband piezoelectric vibration energy harvester is established and its corresponding dynamic characteristics are analyzed, which provides theoretical basis for the practical development of the micro wideband piezoelectric vibration energy harvester. The finite analysis software ANSYS is adopted to simulate the output performances the micro wideband piezoelectric vibration energy harvester. The curves of the dimension parameters of the micro wideband piezoelectric vibration energy harvester versus the resonance frequencies and open-circuit voltages are explored and the optimal parameters are defined. For comparison, the output performances of the micro linear piezoelectric vibration energy harvester under the same vibration excitation are also listed to verify the capacity of broadband frequency response and the power generation of the micro wideband piezoelectric vibration energy harvester. Finally, the prototype of the micro wideband piezoelectric vibration energy harvester is fabricated. The test results show that the fabricated micro wideband piezoelectric vibration energy harvester can generate voltages in the 40 to 140 Hz range under the 0.7g vibration acceleration. Specifically,the piezoelectric cantilever beam 1 produces the maximum output power of 274.87μW and 96.14μW at the first and the second resonant modes, respectively. And the piezoelectric cantilever beam 2 also generates the maximum output power of 157.02μW and 89.23μW at the first and the second resonant modes, respectively.All the tested results show the pretty good output characteristics of the designed micro wideband piezoelectric vibration energy harvester and confirm the possibility of the application of micro wideband piezoelectric vibration energy harvester in the engine vibration environment to power the wireless acceleration nodes in the engine condition monitoring and fault diagnosing systems.