阅读说明：本技术 一种旋转式自调频压电振动能量收集器 (Rotary self-frequency-modulation piezoelectric vibration energy collector ) 是由 邓丽城 吴蓓园 方玉明 于 2019-12-19 设计创作，主要内容包括：本发明是一种旋转式自调频压电振动能量收集器,包括主梁、副梁、质量块和外框,主梁为压电梁,由压电层和衬底层构成,主梁的一端固定在外框上,主梁的另一端与质量块相连,副梁为弹性梁,副梁的一端与外框连接,副梁的另一端与质量块连接,质量块的中间设置有贯穿槽,质量块与主梁通过贯穿槽连接,质量块通过贯穿槽约束在主梁长度方向滑动,外框固定在旋转机构上。本发明的质量块所受的离心力作用于质量块时,质量块质心在主梁上的位置发生变化,调节振动能量收集器的固有频率,实现与转动激励频率相匹配,增加振动能量收集器工作频带宽度,提高结构的可靠性,降低结构设计的难度。(The invention relates to a rotary self-frequency-modulation piezoelectric vibration energy collector which comprises a main beam, a secondary beam, a mass block and an outer frame, wherein the main beam is a piezoelectric beam and consists of a piezoelectric layer and a substrate layer, one end of the main beam is fixed on the outer frame, the other end of the main beam is connected with the mass block, the secondary beam is an elastic beam, one end of the secondary beam is connected with the outer frame, the other end of the secondary beam is connected with the mass block, a through groove is formed in the middle of the mass block, the mass block is connected with the main beam through the through groove, the mass block is restrained to slide in the length direction of. When the centrifugal force borne by the mass block acts on the mass block, the position of the mass center of the mass block on the main beam is changed, the natural frequency of the vibration energy collector is adjusted, the vibration energy collector is matched with the rotation excitation frequency, the working frequency bandwidth of the vibration energy collector is increased, the reliability of the structure is improved, and the difficulty of structural design is reduced.)

1. The utility model provides a rotation type is from frequency modulation piezoelectricity vibration energy collector, includes girder (1), auxiliary girder (3), quality piece (4) and frame (6), its characterized in that: the main beam (1) is a piezoelectric beam and consists of a piezoelectric layer (2) and a substrate layer, one end of the main beam (1) is fixed on the outer frame (6), the other end of the main beam (1) is connected with the mass block (4), the auxiliary beam (3) is an elastic beam, one end of the auxiliary beam (3) is connected with the outer frame (6), the other end of the auxiliary beam (3) is connected with the mass block (4), a through groove (5) is arranged in the middle of the mass block (4), the mass block (4) is connected with the main beam (1) through the through groove (5), the mass block (4) is constrained to slide in the length direction of the main beam (1) through the through groove (5), the outer frame (6) is fixed on a rotating mechanism, and when the rotating mechanism rotates, the piezoelectric collector vibrates under the action of rotation excitation to realize energy collection, the mass block (4) slides on the main beam (1) under the combined action of centrifugal force and elastic force of the auxiliary beam, so that the resonant frequency of the piezoelectric vibration energy collector is adjusted, and the matching with the rotation excitation frequency is realized.

2. A rotary self-modulating piezoelectric vibration energy harvester as in claim 1, wherein: the piezoelectric beam is of a structure with one wide end and the other narrow end or is rectangular.

3. A rotary self-modulating piezoelectric vibration energy harvester according to claim 1 or claim 2, wherein: the upper surface and the lower surface of the piezoelectric layer (2) on the piezoelectric beam are both distributed with piezoelectric materials of electrodes, and electric energy is output by the upper surface and the lower surface of the electrodes.

4. A rotary self-modulating piezoelectric vibration energy harvester as in claim 1, wherein: the auxiliary beam (3) is a spiral elastic beam or a folding beam.

Technical Field

The invention relates to the technical field of energy collection, in particular to a rotary type self-frequency-modulation vibration energy collector.

Background

The rapid development and wide application of microelectronic devices and systems (such as wireless sensing network nodes, medical implant sensors, weapon equipment fault monitoring systems, etc.) require that the power supply system has the characteristics of long service life, small volume, light weight, etc. The traditional chemical energy battery meets technical bottlenecks of short service life, large volume, heavy weight and the like in the development process, becomes one of main obstacles restricting the development of microelectronic devices and systems, can convert vibration energy in the surrounding environment into electric energy, can theoretically realize infinite power supply time, and has the advantages of small volume, light weight, high energy density and the like, is one of the most promising technical schemes for realizing the power supply of the microelectronic devices and the systems by replacing the traditional chemical energy battery, has attracted great interest in both academic circles and industrial circles, and has been rapidly developed in recent years.

High output performance vibration energy harvesters require vibration energy harvesters with both high vibration energy harvesting and vibration energy conversion capabilities, and currently most vibration energy harvester vibration energy harvesting is mainly based on resonance effects. The vibration energy collector based on the resonance effect can only have better vibration energy obtaining capability within a narrow frequency range (about 1 Hz), and the vibration frequency of the environmental vibration source generally changes randomly within a wide frequency range, namely, the contradiction that the working frequency of the vibration energy collector is not matched with the excitation frequency exists, so that the vibration energy collector has low output performance and narrow working frequency band, and becomes a key factor restricting the practicability of the vibration energy collector.

In order to solve this problem, some new methods have been proposed in recent years: shad Roundy et al (Smartmaterials & structures.2014,23(10):105004) propose a broadband vibration energy harvester for use in tire pressure monitoring systems using a non-linear frequency band extending method. The dynamic characteristic of the offset pendulum is realized through the installation mode of the vibration energy collector, the nonlinear bistable characteristic is realized through the small ball which is restricted to move between the baffles, and the developed device expands the working frequency bandwidth of the vibration energy collector. The bandwidth extension of this approach is still limited; and the nonlinear structure needs to introduce auxiliary mechanisms such as magnets and the like, so that the complexity of the vibration energy collector structure is increased. The Wang Yu-Jen topic group (Sensors and microphones A: physical.2019(285):25-34) uses centrifugal force to change the cantilever beam section inertia moment to adjust the resonance frequency of the vibration energy collector, and proposes a new structure of the self-frequency-adjusting vibration energy collector. But the structure introduces roller bearings, which increases the complexity of the structure; meanwhile, the ladder-shaped beam in the structure moves back and forth in the roller bearing along with the change of the vehicle speed, so that the piezoelectric material or the electrode on the surface of the piezoelectric material is easy to damage, and the reliability of the device is reduced.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a rotary self-frequency-modulation vibration energy collector, which utilizes the centrifugal force of a mass block in the rotating process to change the position of the mass center of the mass block on a main beam to adjust the resonance frequency of the vibration energy collector, so as to realize the matching with the excitation frequency, thereby expanding the working frequency band range of the vibration energy collector and improving the output performance of the vibration energy collector.

In order to achieve the purpose, the invention is realized by the following technical scheme:

the invention relates to a rotary self-frequency-modulation piezoelectric vibration energy collector, which comprises a main beam, a secondary beam, a mass block and an outer frame, wherein the main beam is a piezoelectric beam and consists of a piezoelectric layer and a substrate layer, one end of the main beam is fixed on the outer frame, the other end of the main beam is connected with the mass block, the secondary beam is an elastic beam, one end of the secondary beam is connected with the outer frame, the other end of the secondary beam is connected with the mass block, a through groove is arranged in the middle of the mass block, the mass block is connected with the main beam through the through groove, the mass block is restrained to slide in the length direction, when the rotating mechanism rotates, the piezoelectric vibration energy collector vibrates under the action of rotation excitation to realize energy collection, the mass block is under the combined action of centrifugal force and the elastic force of the secondary beam, the main beam slides to adjust the resonant frequency of the piezoelectric vibration energy collector, so that the piezoelectric vibration energy collector is matched with the rotation excitation frequency.

The invention is further improved in that: the piezoelectric beam is of a structure with one wide end and the other narrow end or is rectangular.

The invention is further improved in that: the upper surface and the lower surface of the piezoelectric layer on the piezoelectric beam are both distributed with piezoelectric materials of the electrodes, and electric energy is output by the upper surface electrode and the lower surface electrode.

The invention is further improved in that: the secondary beam is a spiral elastic beam or a folding beam.

The invention has the beneficial effects that: (1) when the centrifugal force borne by the mass block acts on the mass block, the position of the mass center of the mass block on the main beam is changed, so that the effective length of the cantilever beam is changed, the main beam is of a non-rectangular structure, the effective section moment of inertia of the main beam can be changed simultaneously, the natural frequency of the vibration energy collector can be adjusted more flexibly, the vibration energy collector is matched with the rotation excitation frequency, and the working frequency bandwidth of the vibration energy collector is increased;

(2) the mass block is contacted with the main beam but is not fixed, so that the main beam is prevented from being damaged by large centrifugal force of the mass block, and the reliability of the structure is improved;

(3) the secondary beam only has non-zero tensile rigidity, has no influence on the resonance frequency of the main beam in bending vibration, and reduces the difficulty of structural design.

Drawings

FIG. 1 is a schematic diagram of the overall structure of a rotary self-frequency-modulated piezoelectric vibration energy collector of the present invention.

Figure 2 is a schematic view of the installation of the collector of the present invention.

Figure 3 is a schematic view of the construction of the collector with the main beam being rectangular.

Fig. 4 is a schematic structural view of a collector having a shape that a main beam is narrow at one end and wide at the other end.

Fig. 5 is a schematic structural view of the sub-beam being a folded beam.

FIG. 6 is a plot of vehicle speed versus wheel rotational frequency and vibration energy harvester natural frequency.

FIG. 7 is a graph of vehicle speed versus secondary beam spring rate and mass sliding displacement satisfying curve 6.

Detailed Description

In the following description, for purposes of explanation, numerous implementation details are set forth in order to provide a thorough understanding of the embodiments of the invention. It should be understood, however, that these implementation details are not to be interpreted as limiting the invention. That is, in some embodiments of the invention, such implementation details are not necessary. In addition, some conventional structures and components are shown in simplified schematic form in the drawings.

As shown in fig. 1-7, the invention is a rotary self-frequency-modulation piezoelectric vibration energy collector, which comprises a main beam 1, a secondary beam 3, a mass block 4 and an outer frame 6, wherein the main beam 1 is a piezoelectric beam and is composed of a piezoelectric layer 2 and a substrate layer, one end of the main beam 1 is fixed on the outer frame 6, the other end of the main beam 1 is connected with the mass block 4, the secondary beam 3 is an elastic beam, the elastic stiffness is not zero in the length direction of the main beam 1 and can be ignored in other directions, one end of the secondary beam 3 is connected with the outer frame 6, the other end of the secondary beam 3 is connected with the mass block 4, a through groove 5 is arranged in the middle of the mass block 4, the mass block 4 is connected with the main beam 1 through the through groove 5, the mass block 4 is constrained to slide in the length direction of the main beam 1 through the through groove 5, and, the sliding constraint is carried out on the length direction of the main beam 1, the outer frame 6 is fixed on a rotating mechanism such as an automobile hub 7, when the rotating mechanism rotates, the piezoelectric vibration energy collector vibrates under the action of rotation excitation to realize energy collection, the mass block 4 slides on the main beam 1 under the combined action of centrifugal force and elastic force of the auxiliary beam to adjust the resonance frequency of the piezoelectric vibration energy collector, the matching with the rotation excitation frequency is realized, the working frequency bandwidth of the energy collector is expanded, the structure is simple, easy to design and high in reliability, the piezoelectric beam is a structure with one wide end and the other narrow end, as shown in figures 1 and 4, the piezoelectric beam can be rectangular as shown in figure 3 or can be in other shapes determined according to actual needs, the piezoelectric material of electrodes is distributed on the upper surface and the lower surface of the piezoelectric layer 2 on the piezoelectric beam, and can be lead zirconate titanate (PZT), AlN nitride, ZnO oxide, Sc_xAl_1-xN, electric energy is output by the upper surface electrode and the lower surface electrode, the auxiliary beam 3 is a spiral elastic beam such as figure 1 or a folding beam such as figure 5 or a beam with other structures determined according to actual requirements, the auxiliary beam is connected with the mass block and the outer frame together in a manner that one end is simply supported and the other end is fixedly supported or both ends are simply supported,

the working principle of the rotary self-frequency-modulation piezoelectric vibration energy collector is as follows: when the vibration energy collector rotatesWhen the mechanism rotates with the hub 7, the vibration energy collector is subjected to an acceleration of 1g (g 9.8 m/s)²) Excitation is rotational excitation of rotational frequency; when the resonant frequency of the vibration energy collector is basically consistent with the rotation frequency, the vibration energy collector generates large vibration to output electric energy, the centrifugal force borne by the mass block 4 is increased along with the increase of the rotation frequency of the rotating mechanism, so that the mass block 4 slides on the main beam 1, the natural frequency of the vibration energy collector is adjusted, and the sliding displacement of the mass block 4 on the main beam 1 is accurately controlled under the action of the elastic force of the auxiliary beam 3 and the centrifugal force, so that the adjusted natural frequency of the vibration energy collector is still matched with the rotation excitation frequency, and the aim of expanding the working frequency range of the vibration energy collector is fulfilled.

Taking the rotation of an automobile tire as an example, as shown in fig. 6-7, when the vehicle speed is in a range of 60-105 km/h, the secondary beam 3 is a linear spring, that is, the elastic coefficient is unchanged along with the sliding displacement of the mass block 4, the natural frequency of the vibration energy collector is basically matched with the rotation frequency, the secondary beam 3 is introduced in an independent beam form, and the subsequent secondary beam with the linear spring characteristic is easy to design.

Furthermore, when the rotating mechanism rotates at a high speed, the mass block 4 can be acted by a large centrifugal force, and the mass block 4 and the main beam 1 are connected through the through groove 5, so that the centrifugal force borne by the mass block 4 can not theoretically act on the main beam 1 to generate a centrifugal force direction force, the risk of breaking the vibration energy collector structure by the large centrifugal force is avoided, and the reliability of the structure is improved.

Furthermore, the secondary beam 3 has elastic rigidity in the length direction of the main beam 1, and the mass block 4 slides freely in the length direction of the main beam 1, so that the introduction of the secondary beam 3 does not affect the natural frequency of the vibration energy collector, and the difficulty of structural design is reduced.

It is obvious to those skilled in the art that the present invention is not limited to the above embodiments, and it is within the scope of the present invention to adopt various insubstantial modifications of the method concept and technical scheme of the present invention, or to directly apply the concept and technical scheme of the present invention to other occasions without modification.