This application claims priority to Chinese Patent Application No. 202210917857.4, filed on Aug. 1, 2022, which is hereby incorporated by reference in its entirety.
The present disclosure relates to the technical field of renewable energy power generation, and particularly to a vibration energy harvester, a power accumulator and a power supplier.
With the development of science and technology, the consumption of energy sources is increasing all over the world, while the reserves of traditional non-renewable resources such as oil and coal are gradually exhausted, which is far from ensuring the future needs of human lives. In addition, climate and environmental problems, such as greenhouse effect caused by the traditional energy sources, are increasingly restricting the survival and development of human beings. Therefore, the development of new renewable clean energy sources has gradually become an important development issue in various countries. Like the commonly used clean energy sources such as solar energy, wind energy and ocean energy, vibration energy is widely existed in the human environment, but is rarely collected and utilized. Compared with other clean energy sources, the vibration energy normally existing in mechanical structures is less affected by external factors such as weather and closely related to human productions and lives. Therefore, the collection and utilization of the vibration energy have attracted more and more attention.
As the vibration may cause structural deformation, the commonly used method for vibration energy harvesting is utilizing piezoelectric material to convert the deformation energy generated by vibration into electrical energy. A large number of studies show that this method is simple and effective. Therefore, a variety of linear and nonlinear vibration energy harvesters were invented.
The linear vibration energy harvester has a high energy conversion efficiency only at its fixed frequency. Therefore, its energy absorption effect will be greatly reduced once the vibration frequency changes. As a result, the linear vibration energy harvester is difficult to be popularized and used in practical application scenarios with variable vibration frequencies. However, the nonlinear vibration energy harvester has the advantages of wide working frequency range, large output energy and high conversion efficiency due to its nonlinear characteristics, so it is very suitable for practical application scenarios with variable vibration frequencies. The traditional magnetic bistable vibration energy harvester has the disadvantages of complex structure and high energy consumption. The bistable vibration energy harvester fabricated by composite laminate has the disadvantages of complex manufacturing, uncontrollable deformation and simplex mounting due to the limitation of the material itself.
It should be noted that the above description of the background art is only for the convenience of clearly and completely explaining the technical solutions of the present disclosure, and to facilitate the understanding by those skilled in the art. Such technical solutions should not be considered as well known to those skilled in the art merely because they are set forth in the background section of the present disclosure.
The present disclosure provides a vibration energy harvester, a power accumulator and a power supplier to solve at least part of the above problems pointed out in the background section.
It is a first aspect of the present disclosure to provide a vibration energy harvester, which includes a multi-stable shell with one or more bistable regions and at least one piezoelectric element bonded on the surface of the multi-stable shell. Each of the bistable regions has two different stable configurations switchable into each other. The switching process of the bistable region between the two stable configurations is a nonlinear motion. Different combinations of the stable configurations of the one or more bistable regions make the multi-stable shell have a plurality of different stable configurations. The one or more bistable regions are switched between the two stable configurations thereof when being excited by vibration energy, so that the multi-stable shell is switched between the plurality of stable configurations to deform the piezoelectric element to generate electric energy.
It is a second aspect of the present disclosure to provide an electric accumulator, including an electric accumulation element and the vibration energy harvester according to the embodiments of the first aspect. The electric accumulation element is electrically coupled to a piezoelectric element of the vibration energy harvester to store electric energy generated by the piezoelectric element.
It is a third aspect of the present disclosure to provide a power supplier, including a power transmission circuit and the vibration energy harvester according to the embodiments of the first aspect. The power transmission circuit is electrically coupled to a piezoelectric element of the vibration energy harvester to supply electric energy generated by the piezoelectric element to a load.
The embodiments of the present disclosure have the following advantageous effects.
1. Under the excitation of vibration energy, the multi-stable shell in the present disclosure can be subjected to a multi-stable transformation to cause a large deformation, which makes the piezoelectric material of the piezoelectric element produce a piezoelectric effect to generate electric energy. Compared with the prior art, the power generation is larger and the energy conversion efficiency is higher.
2. The multi-stable shell in the present disclosure represents nonlinear characteristics during the configuration transformation, so that the energy harvester has a broadband characteristic and achieves a good energy absorption effect in a certain frequency band, thus being applicable to practical scenarios with variable vibration frequencies.
3. The multi-stable shell of the present disclosure has a local bistable characteristic, which enables the energy harvester to have a greater design freedom and can be designed in different configurations according to different vibration needs, so it is easy in machining and controllable in deformation.
With reference to the following description and drawings, the specific embodiments of the present disclosure are disclosed in detail, and the ways in which the principles of the present disclosure can be adopted are pointed out. It should be appreciated that the embodiments of the present disclosure are not limited in scope. Within the scope of the spirit and clauses of the appended claims, the embodiments of the present disclosure include many changes, modifications and equivalents.
The drawings are included to provide a further understanding of the embodiments of the present disclosure, constitute a part of the specification, illustrate the embodiments of the present disclosure, and together with the description, explain the principles of the present disclosure. Obviously, the drawings in the following description only illustrate some embodiments of the present disclosure. Those of ordinary skill in the art can obtain other drawings from these drawings without any inventive efforts. In the drawings:
The foregoing and other features of the present disclosure will become apparent from the following description with reference to the drawings. In the description and drawings, specific embodiments of the present disclosure are specifically disclosed, which are some embodiments in which the principles of the present disclosure can be applied. It should be appreciated that the present disclosure is not limited to the described embodiments, but on the contrary, the present disclosure includes any modification, variation and equivalent that falls within the scope of the appended claims. In the embodiments of the present disclosure, unless otherwise stated, the terms ‘a plurality of’ and ‘multiple’ both means two or more, and the term ‘multi-stable’ means two or more stable states.
The implementations of the embodiments of the present disclosure will be described below with reference to the drawings.
Embodiments of a first aspect of the present disclosure provide a vibration energy harvester.
As illustrated in
The multi-stable shell 1 has one or more bistable regions 3. In the embodiment illustrated in
Different combinations of the stable configurations of one or more bistable regions 3 make the multi-stable shell 1 have different stable configurations. When the multi-stable shell 1 includes n bistable regions 3, theoretically there exist 2n stable configurations for the multi-stable shell 1, so that the multi-stable shell 1 has multi-stable characteristics.
The configuration switching of the bistable region 3 changes the configuration of the bistable shell 1. Referring to
The piezoelectric element 2 is fixed on a surface of the multi-stable shell 1. For example, one surface of the multi-stable shell 1 is provided with the piezoelectric element 2, or two opposite surfaces of the multi-stable shell 1 are provided with the piezoelectric elements 2, respectively. The number of the piezoelectric element 2 on each surface of the multi-stable shell 1 may be one or more.
When the vibration energy to be collected is continuously applied to the multi-stable shell 1, the configuration of the bistable region 3 is continuously switched between the two stable configurations thereof as excited by the vibration energy continuously. The continuous switching of the configurations of one or more bistable regions 3 makes the multi-stable shell 1 continuously switch between its multiple stable configurations, so that the piezoelectric element 2 is continuously deformed (as illustrated in
It should be noted that vibration energy may be generated non-artificially such as by a vibration source, and may also be generated by an artificially applied external force. The vibration energy may be directly applied to the bistable region 3. Alternatively, the vibration energy may be applied to any other region (called as a non-bistable region) of the multi-stable board 1 except the bistable region 3, so as to be transferred from the non-bistable region to the bistable region 3. Alternatively, the vibration energy may be applied to both the bistable region 3 and the non-bistable region.
In this embodiment of the present disclosure, the multi-stable shell 1 is provided, and subjected to a multi-stable transformation under the excitation of the vibration energy. The multi-stable transformation causes a large deformation, so that the piezoelectric material of the piezoelectric element 2 causes a strong piezoelectric effect to generate more electric energy, thus generating more electricity and achieving higher energy conversion efficiency compared with the prior art. The electric energy generated by the piezoelectric element 2 may be directly stored in a storage battery, or may be directly transmitted to small electric devices such as sensors after being processed.
As the multi-stable shell 1 has the local bistable characteristic, the harvester has a greater design freedom and may be designed in different configurations according to different vibration needs, while being easy in machining and controllable in deformation.
The process of switching between the two stable states for the bistable region 3 is destabilising from one stable state and snapping into the other stable state, and the switching motion of the bistable region 3 between the two stable states is a nonlinear motion. In other words, the configuration switching of the bistable region 3 is nonlinear, so that the multi-stable transformation of the multi-stable shell 1 is also nonlinear (called as a nonlinear multi-stable transformation). Therefore, the energy harvester of the present disclosure is a nonlinear energy harvester. Compared with the linear energy harvester which only has a good energy absorption effect at its own natural frequency, the energy harvester of the present disclosure achieves a good energy absorption effect in a certain frequency band, and has a broadband characteristic, thus being applicable to practical scenarios with variable vibration frequencies.
In order to verify the broadband characteristic of the energy harvester of the present disclosure, and to compare the energy conversion efficiency of the energy harvester of the present disclosure with that of the linear energy harvester of the prior art, frequency sweep tests are carried out on the two types of energy harvesters, respectively.
As illustrated in
The plurality of output voltage signal peaks occurring in the frequency band 14 (see the circle 15 in
Through the research, the inventor finds that the effective working frequency band of the vibration energy harvester of the present disclosure is positively correlated to the vibration intensity (e.g., the acceleration) of the vibration source, and the bandwidth of the effective working frequency band increases along with the vibration intensity. In the design of the vibration energy harvester, the working frequency band of the vibration energy harvester may be designed according to the vibration frequency of the vibration source, so as to make the effective working frequency band of the vibration energy harvester cover the vibration frequency of the vibration source. For example, during implementation, the working frequency band of the vibration energy harvester is designed by controlling the size and shape of the bistable shell 1, the parameters of the piezoelectric material of the piezoelectric element 2, the position of the piezoelectric element 2 on the bistable shell 1, and the residual stress introduced into the bistable region 3, so as to make the effective working frequency band cover the vibration frequency of the vibration source. For the manufactured vibration energy harvester, the later adjustment of the effective working frequency band may be achieved by adjusting the residual stress of the bistable region 3 and the position or the parameters of the piezoelectric element 2. Therefore, the vibration energy harvester of the present disclosure further has the advantage that its effective working frequency band is adjustable, so that a suitable working frequency band of the vibration energy harvester can be customized according to the vibration sources with different vibration intensities and vibration frequencies.
In some embodiments, the frequency of the vibration energy to be collected may change within a certain frequency range, which is the effective working frequency range of the vibration energy harvester. Specifically, the effective working frequency range is a range that widens from the natural frequency of the multi-stable shell to both sides, and the specific extending range is positively correlated to the intensity of the vibration source. Generally, the effective working frequency range of the vibration energy harvester is a low frequency range of 1 Hz to 200 Hz.
In some embodiments, the nonlinear switching motion of the bistable region 3 between the two different stable states is snap-through. For example, under the excitation of the vibration energy, the bistable region 3 can be switched between the downward convex configuration (
In some embodiments, the multi-stable shell 1 is obtained by treating a local region of a metal shell with the surface mechanical attrition treatment (SMAT) technology. The treated local region becomes the bistable region 3 having a nanocrystalline surface layer with a gradient structure, so that the bistable region 3 has the mechanical properties as excellent as the gradient nanostructure material. Based on the treatment method, the multi-stable shell 1 has a simple manufacturing process, and can be obtained by machining a metal shell with an arbitrary shape.
Optionally, the metal shell is made of aluminum alloy, stainless steel, titanium alloy, nickel-based alloy, magnesium alloy or other metal materials.
Optionally, the metal shell is a flat or curved shell with uniform or uneven thickness.
Optionally, metal shell has a thickness of 0.1 mm to 2 mm.
In this embodiment, the surface mechanical attrition treatment technology may be adopted to treat the front and back sides of the local region of the metal shell. The grains of surface layer material of the treated local region (also called as a treated region) are refined to nanometer level. The grain size decreases as being closer to the surface layer presenting a typical characteristic of gradient nanostructure, which improves the strength, corrosion resistance and fatigue resistance of the bistable region 3. While the grain is refined, the residual stress is also introduced into the material of the treated region. The material of the treated region is plastically deformed under the action of the surface mechanical attrition treatment technology, and the deformation will be restrained or restricted by the surrounding untreated region 4 (also called as the non-bistable region, see
For example,
The shape of the bistable region 3 may be circular (as illustrated in
In some embodiments, as illustrated in
In order to conveniently connect the bistable region 3 and the connecting rod 6, a through hole 5 may be punched at any position in the bistable region 3, and the connecting rod 6 passes through the through hole 5. The through hole 5 provided at the circle center of the bistable region 3 will facilitate the transmission of the vibration energy. When the shape of the multi-stable shell 1 is centrosymmetric, such as a square or a circle, and the shape of the bistable region 3 is circular, the connection mode of this embodiment is particularly suitable for connecting the bistable region 3 and the vibration source 7.
In other embodiments, as illustrated in
In some embodiments, the vibration energy harvester further includes a vibration source 7 with a variable vibration frequency. In order to obtain as much vibration energy as possible, the vibration source 7 is directly connected to the multi-stable shell 1.
In some embodiments, a single piezoelectric element 2 may be a single piezoelectric piece. Alternatively, a single piezoelectric element 2 may be formed by a plurality of piezoelectric pieces connected in series or in parallel (as illustrated in
In some embodiments, as illustrated in
Since the bistable region 3 has a large deformation during the configuration switching of the multi-stable shell 1 and the untreated region 4 has a small deformation during the configuration switching of the multi-stable shell 1, the piezoelectric elements 22 on the surface of the bistable region 3 may be made of a piezoelectric material with a large deformation capacity, such as PVDF, while the piezoelectric element 21 on the surface of the untreated region 4 may be made of a piezoelectric material with a small deformation capacity, such as piezoelectric ceramics or piezoelectric crystals. Certainly, the piezoelectric element 21 on the surface of the untreated region 4 may also be made of a piezoelectric material with a large deformation capacity. Therefore, the present disclosure allows the use of piezoelectric elements with different deformation capabilities.
In some embodiments, the surface of the piezoelectric element 2 is attached and fixed to the surface of the multi-stable shell 1. The piezoelectric element 2 may be fixed to the surface of the multi-stable shell 1 by adhesive, and the specific adhesive method may be local adhesive or integral adhesive. However, the present disclosure is not limited thereto, and the piezoelectric element 2 may be connected to the multi-stable shell 1 in other ways, such as a detachable connection.
As illustrated in
Since the structure and the effect of the vibration energy harvester 100 have been described in detail in the embodiment of the first aspect, relevant contents are incorporated here, and the description is omitted.
As illustrated in
Since the structure and the effect of the vibration energy harvester 100 have been described in detail in the embodiment of the first aspect, relevant contents are incorporated here, and the description is omitted.
In some embodiments, the power transmission circuit 40 includes a rectifier 41, a super capacitor 42 and a voltage regulating device 43 which are electrically coupled in sequence. The rectifier 41 is electrically coupled to the piezoelectric element 2 of the vibration energy harvester 100. The electric energy generated by the piezoelectric element 2 is converted into direct current by the rectifier 41, then stored in the super capacitor 42, and then regulated by the voltage regulating device 43 and supplied to the load 50.
The exemplary embodiments of the present disclosure are described above with reference to the drawings. Many features and advantages of these embodiments will be clear from the detailed description, so the appended claims are intended to cover all the features and advantages of these embodiments that fall within their true spirit and scope. In addition, since many modifications and changes are easily conceivable for those skilled in the art, it is not intended to limit the embodiments of the present disclosure to the precise structures or operations illustrated and described, but to cover all suitable modifications and equivalents falling within the scope.
Number | Date | Country | Kind |
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202210917857.4 | Aug 2022 | CN | national |