It is in great need to achieve continuous battery-free wireless sensing and monitoring of an amount of ultra-low-frequency large-scale rotational machines in transportation, civil engineering, manufacturing, and energy industry. Rotational piezoelectric energy harvesters are promising candidates to power sensors for their high energy densities and ease of integration. However, meeting the sufficient and continuous power supply needs of long-distance sensors for the Internet of Things (IoT) while maintaining the small volume and mass of harvesters remains a challenging task. To overcome this challenge, this work firstly implements the internal impact mechanism to a rotational centrifugal softening piezoelectric energy harvester to achieve its high output, lightweight and small-scale characteristics. On one hand, the internal impact effect utilizes the velocity difference between the piezoelectric beam and sliding mass to enlarge the deflection of piezoelectric material and boost the energy output. On the other hand, the centrifugal softening effect reduces the resonant frequency of harvester, leading to the harvester suitably used for the ultra-low-frequency rotation environment. Theoretical and experimental results demonstrate that the proposed harvester can achieve the normalized energy densities of 17.39 μW/(g Hz) and 1800.97 μW/(cm3 Hz) that stand out among the previously reported rotational piezoelectric energy harvesting devices. Additionally, it is proven experimentally that the energy harvester can achieve the self-powered LoRa system under ultra-low-frequency rotations. The proposed harvester demonstrates significant potential for future battery-free sensors in large-scale rotational machinery monitoring.

中文翻译：

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利用内部冲击效应的高输出、轻量、小型旋转压电能量收集器


在交通、土木工程、制造和能源行业，非常需要实现对大量超低频大型旋转电机的连续无电池无线传感和监控。旋转压电能量收集器因其高能量密度和易于集成而成为为传感器供电的有前途的候选者。然而，在保持收集器的小体积和质量的同时，满足物联网 （IoT） 长距离传感器的充足和持续电源需求仍然是一项具有挑战性的任务。为了克服这一挑战，这项工作首先将内部冲击机构实现到旋转离心软化压电能量收集器上，以实现其高输出、轻量化和小型化的特点。一方面，内部冲击效应利用压电束和滑动质量之间的速度差来扩大压电材料的挠度并提高能量输出。另一方面，离心软化效果降低了收割机的谐振频率，使收割机适合用于超低频旋转环境。理论和实验结果表明，所提出的收集器可以达到 17.39 μW/（g Hz） 和 1800.97 μW/（cm3 Hz） 的归一化能量密度，这在以前报道的旋转压电能量收集装置中脱颖而出。此外，实验证明，能量采集器可以在超低频旋转下实现自供电的 LoRa 系统。拟议的采集器展示了未来无电池传感器在大规模旋转机械监测中的巨大潜力。