Vibration energy collector

Abstract

The invention provides a vibration energy harvester. The device comprises a base, and the base is fixed to a host device during use; one ends of the main cantilevers are fixed on the base, and the other ends are free ends of the main cantilevers; the main frame is fixedly connected with the free end of the main cantilever; the vibrating plate is elastically connected with the main frame; the magnetic power generation devices are arranged between the vibration plate and the base and are provided with magnets and coils which can move relatively, one of the magnets and the coils is fixed to the vibration plate, and the other one of the magnets and the coils is fixed to the magnetic power generation devices. The vibration energy collector has a plurality of different resonance frequencies which are not far away from each other in a certain frequency interval, and corresponds to different vibration modes with relatively large available amplitudes. Therefore, the vibration energy collector can automatically respond to the working frequency of the host equipment and work in the vibration mode corresponding to the similar resonant frequency, the self-adaption function of the vibration energy collector to the frequency of the host equipment is achieved, and meanwhile the total power generation power of the vibration energy collector is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration energy collection, and in particular to a vibration energy collector. Background Art

[0002] Ubiquitous distributed sensors are typical representatives of comprehensive informatization under the Internet of Everything. According to the forecast of Forbes magazine in the United States, by 2025, the world will be covered with 1 trillion sensors. However, the traditional wiring power supply has the spatial size limitations of the environment and location, and the battery power supply has the time scale limitations of reliability and life. Therefore, self-powering through energy harvesting is the key to the widespread application of information equipment. Electromagnetic energy and mechanical energy are micro-energy sources that are commonly found in industrial equipment, transportation, power systems and other environments. They have the advantages of long-lasting stability and high energy, so it is very important to design a device that converts the three energies of machine, magnetism and electricity into each other.

[0003] Vibration energy harvester is a device that converts mechanical energy in the environment into electrical energy through piezoelectric effect and electromagnetic effect. It has the advantages of small size, high energy density, maintenance-free, green and environmental protection, and is not limited by the capacity of traditional chemical batteries. It can provide long-term power supply for ubiquitous distributed sensors such as unattended environmental monitoring, building safety monitoring and other related equipment.

[0004] In order to improve the collection and conversion efficiency of vibration energy, current research work mainly focuses on the optimization of the structure and size of vibration energy harvesters, the application of high-performance materials, etc., but these methods are limited by theoretical limits. For example, for piezoelectric vibration energy harvesters, the stress of the piezoelectric beam must be limited to the range allowed by the mechanical strength of the material, otherwise the piezoelectric beam will be damaged. In recent years, a new method has been proposed: a composite vibration energy harvester, which realizes multiple energy conversion methods in one vibration pickup structure, breaking through the theoretical limitations of the energy collection and conversion efficiency of a single method, and improving the collection and conversion efficiency of vibration energy.

[0005] The vibration energy collector can be regarded as a second-order vibration system. When the vibration frequency is close to the resonant frequency, resonance will occur, and the output performance of the vibration energy collector is the highest at this time. The resonant frequency of the vibration energy collector in the prior art is generally relatively single. Usually there is only one resonance peak within a certain range. In other words, the vibration collector is only sensitive to a specific vibration frequency and has a higher energy conversion efficiency. The publication number CN115912990A, entitled "A beam-type vibration energy collector with a resonance frequency of 65Hz and its design method", discloses the above-mentioned vibration collector with a single resonance frequency. In addition, on this basis, there are products in the prior art that adjust the resonance frequency of the actual vibration collector by adjusting the structure. It still has only one working resonance frequency on the same stereotyped product, but the resonance frequency can be corrected by certain technical means and matched to the appropriate vibration frequency.

[0006] However, in the actual application of vibration collectors, the vibration frequency of the host device is often not strictly stable. Affected by structural changes, environmental changes, and looseness of the fixed end, the main vibration frequency of the host device generally drifts in the frequency range near the initial vibration frequency. This results in the vibration collector with a single resonant frequency no longer matching the vibration frequency of the host device when the main vibration frequency of the host device drifts, making it difficult to achieve the desired energy conversion efficiency. Summary of the invention

[0007] In order to adaptively ensure the energy conversion efficiency of the vibration energy harvester when the frequency of the host device drifts, the present application provides a vibration energy harvester.

[0008] The technical solution of the present invention provides a vibration energy harvester, comprising a base, which is fixed to a host device when in use; A plurality of main cantilevers, one end of the main cantilever is fixed to the base, and the other end is the free end of the main cantilever; A main frame, the main frame is fixedly connected to the free end of the main cantilever; A vibration plate, the vibration plate is elastically connected to the main frame; There are several magnetoelectric devices, one of which is placed between a vibration plate and a base, and has a magnet and a coil that can move relatively, one of the magnet and the coil is fixed to the vibration plate, and the other is fixed to the magnetoelectric device.

[0009] Preferably, it also includes a plurality of secondary cantilevers, one end of which is fixed to the main frame and the other end is the free end of the secondary cantilever, and a magnetoelectric device is arranged between the free end of the secondary cantilever and the base.

[0010] Preferably, the main cantilever and / or the secondary cantilever has a piezoelectric conversion function to convert the mechanical deformation thereof into electrical energy through the piezoelectric effect.

[0011] Preferably, the primary cantilever and / or the secondary cantilever extend parallel to the base surface.

[0012] Preferably, the secondary cantilevers are an even number and are symmetrically distributed in pairs around the main frame.

[0013] Preferably, the main cantilever is arranged equiangularly rotated around the main frame.

[0014] Preferably, the main frame has a hollow area, the vibration plate is placed in the hollow area of ​​the main frame, and the vibration plate is connected to the main frame via a plurality of elastic components on all sides.

[0015] Preferably, the plurality of magnetoelectric devices are distributed between the vibration plate and the main frame, and the plurality of magnetoelectric devices cover the projection area of ​​the vibration plate on the surface of the base.

[0016] Preferably, there are two main cantilevers, which are symmetrically placed on both sides of the main frame; an even number of secondary cantilevers extend around the main frame in parallel to the direction of the main cantilevers, and an even number of secondary cantilevers are symmetrically placed on both sides of the main frame.

[0017] Preferably, an even number of secondary cantilevers are symmetrically arranged relative to the main cantilever.

[0018] The vibration energy collector of the present application forms a composite vibration structure by setting up the main cantilever, main frame and vibration plate, so that the vibration energy collector has several different resonance frequencies that are not far apart within a certain frequency range, and corresponds to different vibration modes with larger available amplitudes. Therefore, the vibration energy collector can automatically respond to the operating frequency of the host device, and work in the vibration mode corresponding to the similar resonance frequency, so as to realize the adaptive function of the vibration energy collector to the frequency of the host device, and at the same time ensure the total power generation power of the vibration energy collector. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the vibration energy collector of the present invention; Figure 2 for Figure 1 A partial enlarged schematic diagram of Figure 3 for Figure 1 A partial enlarged schematic diagram of Figure 4 A record of material properties of a specific embodiment of the vibration energy harvester of the present invention; Figure 5 Schematic diagram of vibration frequencies and vibration shapes of multiple vibration modes of a specific embodiment of the vibration energy harvester of the present invention.

[0020] In the figure: 1: base; 2: main cantilever; 3: main frame; 4: secondary cantilever; 41: piezoelectric sheet; 5: elastic member; 6: vibration plate; 7: magnetoelectric device; 71: magnet; 72: coil. DETAILED DESCRIPTION

[0021] The following is a detailed description of this patent type in conjunction with the accompanying drawings and specific embodiments. In this specification, the dimensions of the drawings do not represent the actual size ratios. The drawings are only used to reflect the relative position relationship and connection relationship between the components. Components with the same name or the same number represent similar or identical structures and are only for illustrative purposes.

[0022] In the application practice of vibration collectors, the vibration frequency of the host device installed in it often drifts during operation due to various reasons. Taking the power transformer as an example, the main vibration frequency of the initially installed power transformer is about 40Hz. After a period of operation, due to structural relaxation, the actual vibration frequency may be reduced to between 30-40Hz, or even lower. In addition, when installed outdoors, the frequency will drift by about 10Hz due to the influence of ambient temperature and humidity. Therefore, it is difficult to always form a good resonance when the frequency of a similar host device changes using a vibration energy collector with a fixed resonant frequency. Therefore, from the perspective of long-term operation, the vibration energy collection efficiency of similar vibration energy collectors is not optimal, and there is still a large room for optimization. For existing vibration energy collectors with adjustable resonant frequency, they do not have an adaptive function. The adjustment of the resonant frequency needs to be achieved through artificial changes in the structure. Generally, it is adjusted to match a specific host device before application. In fact, they do not have the function of adaptive resonant frequency.

[0023] The technical solution of the present application provides a vibration energy collector with a vibration frequency adaptive function. Its essence is to form multiple spare resonance frequencies within a certain resonance frequency range through the structural design of the vibration energy collector, so that when the vibration frequency of the host device changes, a vibration form with higher conversion efficiency can be formed at different spare resonance frequencies. Since the distance between the multiple spare vibration frequencies is not far, the vibration frequency variation range of the host device can be well covered, so that it can provide significantly higher vibration energy conversion efficiency during long-term and medium-term operation.

[0024] Figure 1 This is a schematic diagram of the structure of the vibration energy harvester of the present application. Figure 2 as well as Figure 3 Both Figure 1A partially enlarged schematic diagram. It includes a base 1, which is fixed to the host device when in use. A plurality of main cantilevers 2 are arranged on the base 1, and the main frame 3 is fixedly connected to the free end of the main cantilever 2. Generally, the free ends of the plurality of main cantilevers 2 are fixedly connected to 3. At this time, under a certain vibration mode, the vibrations of the plurality of main cantilevers 2 are transmitted to the main frame 3. The vibration plate 6 is elastically connected to the main frame 3. In the embodiment shown, the vibration plate 6 and the main frame 3 are connected via a plurality of elastic components 5. One end of the elastic component 5 is connected to the vibration plate 6, and the other end is connected to the main frame 3, that is, an elastic transition is formed between the main frame 3 and the vibration plate 6. A plurality of magnetoelectric devices 7 are arranged between the vibration plate 6 and the base 1. The magnetoelectric device 7 has a magnet 71 and a coil 72 that can move relatively. As for the magnet 71 and the coil 72, one is fixed to the vibration plate 6 and the other is fixed to the base 1, so when the vibration plate 6 vibrates, the coil 72 in the magnetoelectric device 7 placed between the bases 1 and 6 is triggered to move relative to the magnet 71, thereby generating an induced current in the magnet 71. The structure extending from the base 1 to the vibration plate 6 is composed of two mutually connected vibration systems connected in series by the main frame 3, thereby forming a composite vibration system, which may form several adjacent resonance peaks.

[0025] Furthermore, a number of secondary cantilevers 4 are extended from the main frame 3, one end of the secondary cantilever 4 is fixed to the main frame 3, and the other end is a free end. A magnetoelectric device 7 is arranged between the free end of the secondary cantilever 4 and the base 1 to convert the magnetoelectric device 7 into electrical energy when the free end of the secondary cantilever 4 vibrates. The existence of the secondary cantilever 4 makes the vibration energy collector form a complex vibration system of series-parallel combination, thereby expanding the structural characteristics of the system, so that the system generates several resonance peaks with larger intensity due to the composite action of multiple sub-vibration systems in a smaller frequency range. It is thus expected to achieve the basic function of having several resonance frequencies of different sizes in a preset frequency range.

[0026] For layout considerations, the main cantilever 2 is usually extended parallel to the surface of the base 1, so that the main frame 3 can be suspended above the surface of the base 1. When the main cantilever 2 vibrates, the main frame 3 vibrates along the normal direction of the surface of the base 1. This maximizes the energy output of the magnetoelectric device 7 between the base 1 and the main frame 3. Based on the same considerations, the secondary cantilever 4 is preferably arranged parallel to the surface of the base 1 in order to facilitate the arrangement of the magnetoelectric device 7, and has a maximized relative displacement with the base 1 at the free end of the secondary cantilever 4.

[0027] When the number of main cantilevers 2 is greater than one, the main cantilevers 2 are preferably arranged in an equiangular rotation around the main frame 3 to ensure that the main frame 3 is evenly stressed and that the main frame 3 is balanced in posture during vibration to avoid excessive deformation of the main frame 3. When the main frame 3 is excessively deformed, or the vibration form is too different, it is not only detrimental to the power generation efficiency of the magnetoelectric device 7 between it and the base 1, but may also cause vibration of the secondary cantilevers 4. If the secondary cantilevers 4 exceed two groups, the secondary cantilevers 4 are preferably symmetrically distributed on the main frame 3 in pairs. When the main frame 3 is periodically tilted, the symmetrical secondary cantilevers 4 alternately have the maximum conversion efficiency.

[0028] From a structural point of view, the vibration plate 6 is hidden in the center of the main frame 3, so the main frame 3 can be designed as a hollow frame, the vibration plate 6 is located in the hollow area of ​​the main frame 3, and the vibration plate 6 is connected to the main frame 3 through a number of elastic components 5 on all sides. Under such a layout, in order to accommodate the elastic component 5 in a limited space and ensure the elastic performance of the elastic component 5, the elastic component 5 usually has a serpentine spring shape. Considering the particularity of the vibration form of the vibration plate 6, it not only displaces, but also may have different vibration modes in different vibration modes, and the area with the largest amplitude is different. Therefore, a number of magnetoelectric devices 7 can be distributed between the vibration plate 6 and the magnetoelectric device 7, and the magnetoelectric device 7 covers a larger area in the projection area of ​​the vibration plate 6. It is ensured that under different vibration modes, the total power generation power of multiple magnetoelectric devices 7 can be guaranteed.

[0029] Under preferred conditions, the implementation of Figure 1 As shown, two groups of main cantilevers 2 are symmetrically placed on both sides of the main frame 3, with a 180-degree relationship. An even number of secondary cantilevers 4 extend parallel to the direction of the main cantilever 2. In fact, the secondary cantilevers 4 are preferably 4, divided into two groups, and placed on both sides of the main cantilever 2. The reason why the secondary cantilever 4 is arranged parallel to the main cantilever 2 is mainly to improve the conversion efficiency of vibration energy. Under this setting, since the main cantilever 2 and the secondary cantilever 4 are concentrated along a symmetrical axis on both sides of the main frame 3, under multiple vibration modes, the main cantilever 2 and the secondary cantilever 4 can vibrate and displace synchronously or alternately to ensure the overall average conversion efficiency of the vibration energy collector. At this time, since the secondary cantilever 4 is parallel to the main cantilever 2. When the main cantilever 2 undergoes alternating vibrations with a phase difference of 180 degrees, the main frame 3 is not only in displacement, but also in periodic tilting, which also drives the secondary cantilever 4 to tilt. Since the setting direction of the secondary cantilever 4 is consistent with the tilting direction, it has an amplification effect, which is conducive to increasing the amplitude of the secondary cantilever 4, thereby improving the energy conversion rate.

[0030] On the basis of the above scheme, in order to improve the energy conversion efficiency within a limited structural space, the main cantilever 2 and / or the secondary cantilever 4 may have a piezoelectric conversion function so that its mechanical deformation is converted into electrical energy through the piezoelectric effect, which can be achieved through the structural design of the main cantilever 2 and the secondary cantilever 4, that is, the main cantilever 2 and the secondary cantilever 4 are both designed with piezoelectric materials and piezoelectric structures. A more general method is to fix piezoelectric patch elements on the main cantilever 2 and the secondary cantilever 4.

[0031] The following is a detailed structure and material parameters of a vibration energy harvester based on dual main cantilevers 2 and four secondary cantilevers 4. The main materials of the main cantilever 2, the main frame 3, the secondary cantilever 4 and the vibration plate 6 are usually made of metal materials, which are aluminum alloys in this embodiment, and the elastic member 5 is made of spring steel. The physical properties of the above materials are as follows: Figure 4 As shown. In order to generate piezoelectric effect, a layer of PZT (lead zirconate titanate, piezoelectric ceramic) coating is also prepared on the surface of the secondary cantilever 4 to generate piezoelectric effect and generate electricity. The overall layout of the vibration energy collector is a double symmetric axis setting, the first symmetric axis is parallel to the setting direction of the main cantilever 2, and the two groups of secondary cantilevers 4 are divided on both sides of the main cantilever 2 relative to the first symmetric axis. The second symmetric axis is perpendicular to the first symmetric axis and parallel to the surface of the base 1. The secondary cantilevers 4 in the group are parallel to the second symmetric axis, and the two main cantilevers 2 are parallel to the second symmetric axis. The length of the main cantilever 2 is 52mm, and the cross-sectional size is 0.5mm*10mm; the length of the secondary cantilever 4 is 42mm, and the cross-sectional size is 0.7*10mm. The total mass of the main frame 3, the elastic member 5, the vibration plate 6 and its accessories is about 7.39g, of which the mass of the vibration plate 6 and its accessories is 6.16g. The cross-sectional size of the elastic member 5 is 0.5mm*1mm, and the total length is 45mm. By serpentine folding, its occupied area is compressed. Analysis of this embodiment shows that its vibration mode structure is as follows: Figure 5 shown.

[0032] Obviously, in the range of 20-50Hz, it shows 6 obvious resonance peaks, and the main cantilever 2, the secondary cantilever 4 and the vibration plate 6 show different vibration modes under each resonance peak, but overall, under different vibration modes, the displacement direction between the magnet 71 and the coil 72 in the magnetoelectric device 7 is consistent with the amplitude direction. Therefore, under different vibration modes, the magnetoelectric function can be well completed. The vibration energy collector is actually composed of a plurality of sub-vibration systems, and the link between the sub-vibration systems is the main frame 3. The main cantilever 2 is located in the first-order vibration system, and the secondary cantilever 4 and the vibration plate 6 belong to different secondary vibration systems. The secondary vibration systems are connected in parallel, while the first-order vibration system and the secondary vibration system are connected in series. This composition structure gives the system more freedom in constraints and is easy to excite different vibration modes, so that a variety of resonance frequencies corresponding to different vibration modes can be obtained within a smaller frequency range. Under different conditions, the vibration of the secondary cantilever 4 is relatively obvious, so the power generation efficiency can also be improved through the piezoelectric effect. In different modes, the main power generation components: the secondary cantilever 4, the combination of the vibration plate 6 has different vibration modes, which can be in phase or in antiphase, which brings about subtle differences in the resonant frequencies under different vibration modes. The corresponding six groups of vibration frequencies are a: 23.944Hz, b: 32.907Hz, c: 39.534Hz, d: 39.825Hz, e: 46.84Hz, f: 49.276Hz. The vibration frequency has a relatively good coverage in the range of 20-50Hz. The vibration plate 6 can mainly be the main vibration mode of up and down displacement vibration, or it can have complex elastic deformation as shown in (b), (c), and (f), resulting in uneven local vibration. Arranging multiple magnetoelectric devices under the vibration plate 6 can ensure the energy output of the vibration plate 6 under various vibration modes. In this case, if the actual operating frequency of the host device changes within this range, the vibration energy collector can respond to the vibration of the host device through the adjacent resonance peak, mainly activating the corresponding vibration mode to achieve energy collection.

[0033] The vibration energy collector of the present application has the characteristics of multi-modality and piezoelectric electromagnetic composite vibration energy collection. Under the joint action of multiple vibration units, the collector has 6 resonance frequencies in the range of 20-50Hz, which expands the frequency bandwidth of vibration energy collection, allowing the collector to maintain the maximum output power in a variety of environments. Several magnets are evenly distributed in the part with the largest vibration amplitude of the collector, so that the device has high energy density and energy utilization. It uses a new structure to cleverly combine piezoelectric and electromagnetic vibration energy collectors, breaking through the theoretical limitations of the conversion efficiency of single-mode vibration energy collectors, and has the advantages of high energy conversion efficiency and high output performance.

[0034] The above content only describes the preferred implementation methods of this patent type and does not limit the scope of this patent type. Without departing from the design spirit of this patent type, various modifications and improvements made to the technical solutions of this patent type by ordinary technicians in this field should fall within the protection scope determined by the claims of this patent type.

Claims

1. A vibration energy harvester, characterized in that: It comprises a base (1), and when in use, the base (1) is fixed to the host device; A plurality of main cantilevers (2), one end of the main cantilever (2) is fixed to the base (1), and the other end is the free end of the main cantilever (2); A main frame (3), the main frame (3) is fixedly connected to the free end of the main cantilever (2); A vibration plate (6), the vibration plate (6) being elastically connected to the main frame (3); A plurality of magnetoelectric devices (7) are provided, wherein the magnetoelectric device (7) is placed between a vibration plate (6) and a base (1), and comprises a magnet (71) and a coil (72) capable of relative movement, wherein one of the magnet (71) and the coil (72) is fixed to the vibration plate (6), and the other is fixed to the magnetoelectric device (7).

2. The vibration energy harvester according to claim 1, characterized in that: It also includes a plurality of secondary cantilevers (4), one end of which is fixed to the main frame (3) and the other end is a free end of the secondary cantilever (4), and a magnetoelectric device (7) is arranged between the free end of the secondary cantilever (4) and the base (1).

3. The vibration energy harvester according to claim 1, characterized in that: The main cantilever (2) and / or the secondary cantilever (4) have a piezoelectric conversion function to convert their mechanical deformation into electrical energy through the piezoelectric effect.

4. The vibration energy harvester according to any one of claims 2 or 3, characterized in that: The main cantilever (2) and / or the secondary cantilever (4) extend parallel to the surface of the base (1).

5. The vibration energy harvester according to any one of claims 2 or 3, characterized in that: The secondary cantilevers (4) are in an even number and are symmetrically distributed in pairs around the main frame (3).

6. The vibration energy harvester according to any one of claims 1 to 3, characterized in that: The main cantilever (2) is arranged around the main frame (3) in an equiangularly rotated manner.

7. The vibration energy harvester according to any one of claims 1 to 3, characterized in that: The main frame (3) has a hollow area, the vibration plate (6) is placed in the hollow area of ​​the main frame (3), and the vibration plate (6) is connected to the main frame (3) via a plurality of elastic components (5) on all sides.

8. The vibration energy harvester according to any one of claims 1 to 3, characterized in that: A plurality of magnetoelectric devices (7) are distributed between the vibration plate (6) and the main frame (3), and the plurality of magnetoelectric devices (7) cover the projection area of ​​the vibration plate (6) on the surface of the base (1).

9. The vibration energy harvester according to any one of claims 1 to 3, characterized in that: There are two main cantilevers (2) symmetrically arranged on both sides of the main frame (3); an even number of secondary cantilevers (4) extend around the main frame (3) in parallel with the direction of the main cantilevers (2), and an even number of secondary cantilevers (4) are symmetrically arranged on both sides of the main frame (3).

10. The vibration energy harvester according to claim 9, characterized in that: An even number of secondary cantilevers (4) are symmetrically arranged relative to the main cantilever (2).

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