Water impact type magnetic coupling nonlinear piezoelectric energy harvesting device

Abstract

This invention discloses a water-impact magnetic coupling type nonlinear piezoelectric energy harvesting device, belonging to the field of piezoelectric material energy harvesting control. The device includes: an upper base plate, an elastic film, a polyvinylidene fluoride (PVDF) piezoelectric film, a lower base plate, permanent magnets, springs, and a fixed circular frame. The elastic film is adhered to the outer cylindrical walls of the concentrically mounted upper and lower base plates, forming a sealed cavity. The PVDF piezoelectric film is adhered to the outer side of the elastic film. The IS pole of the permanent magnet is fixed to the inner wall of the bottom surface of the upper base plate, while the S pole of the permanent magnet II faces downwards and can move relative to the lower base plate. The N poles of the two sets of permanent magnets face each other, and due to the repulsion of like poles, a nonlinear magnetic repulsion force is generated, achieving overall vibration of the piezoelectric device. One end of each of the four springs is fixed to the geometric center of the four sides of the permanent magnet II, and the other end is fixed to the inner cylindrical wall of the fixed circular frame. Under any external vibration excitation, the piezoelectric film is simultaneously subjected to water impact and nonlinear force, resulting in significant elastic deformation and thus energy harvesting.

Description

Technical Field

[0001] This invention relates to a piezoelectric energy harvesting device, and more particularly to a water-impact magnetic coupling type nonlinear piezoelectric energy harvesting device, belonging to the field of piezoelectric material energy harvesting control. Background Technology

[0002] Currently, there are various ways to convert mechanical energy into electrical energy, such as electrostatic energy harvesting, electromagnetic energy harvesting, and piezoelectric energy harvesting. However, electrostatic energy harvesting requires an initial voltage and has low energy density; electromagnetic energy harvesting has relatively low output power and is too bulky; while piezoelectric smart structures, as a type of mechanoelectric coupling structure based on the positive piezoelectric effect of piezoelectric materials, can flexibly realize the conversion between mechanical energy and electrical energy, thereby capturing mechanical energy from the external environment and having a wider range of applications.

[0003] In recent years, nonlinear piezoelectric vibration energy harvesting technology has attracted increasing attention from scholars. Compared with linear energy harvesters, nonlinear piezoelectric energy harvesters have a wider vibration bandwidth and better power generation performance. Theoretical studies have shown that, with the same energy harvesting bandwidth, the output power of a nonlinear energy harvester is 16.5 times that of a linear energy harvester. In piezoelectric energy harvesting systems, magnetic force is a key factor causing nonlinear vibration of the piezoelectric oscillator; therefore, electromagnetic energy conversion modes are often chosen to achieve the desired results.

[0004] In the study of nonlinear dynamics, bistable systems, a classic system, are widely used in various research and engineering projects, such as bistable circuits, bistable switches, and bistable triggers. However, scientists have limited understanding of the more complex tristable piezoelectric energy harvesting systems. Tristable vibrational energy harvesting systems can effectively solve the problems of narrow resonant frequency bands and insufficient power generation in current linear elastic thin-film vibrational energy harvesting systems. If we can further develop and master tristable energy harvesting technology, it will be a significant advancement for the field of energy harvesting. Summary of the Invention

[0005] The purpose of this invention is to provide a water-impact magnetic coupling type nonlinear piezoelectric energy harvesting device, which aims to improve the bandwidth of the piezoelectric energy harvesting device and solve the problem of the single energy harvesting direction of traditional piezoelectric energy harvesting devices.

[0006] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0007] A water-impact magnetic coupling type nonlinear piezoelectric energy harvesting device, characterized in that it comprises: an upper base plate, an elastic film, a polyvinylidene fluoride piezoelectric film, a lower base plate, two sets of permanent magnets, four sets of springs, and a fixed circular frame.

[0008] The water-impact magnetic coupling type nonlinear piezoelectric energy harvesting device is characterized in that: the elastic film is pasted on the outer wall of the cylindrical surface of the concentrically mounted upper and lower base plates, forming a sealed cavity; the polyvinylidene fluoride piezoelectric film is pasted on the outside of the elastic film; the upper base plate, elastic film, polyvinylidene fluoride piezoelectric film, lower base plate, and water placed inside the elastic film constitute a water-impact energy harvesting unit; the two sets of permanent magnets, four sets of springs, and fixed circular frame constitute a nonlinear amplification unit, wherein the IS pole of the permanent magnet is fixed to the inner wall of the bottom surface of the upper base plate, the S pole of the permanent magnet II faces downward, one end of the four sets of springs is fixed to the geometric center of the four sides of the permanent magnet II, and the other end is fixed to the inner wall of the cylindrical surface of the fixed circular frame, and the permanent magnet II can move relative to the lower base plate.

[0009] The water-impact magnetic coupling type nonlinear piezoelectric energy harvesting device is characterized in that: in the nonlinear amplification unit, permanent magnet I and permanent magnet II have their N poles facing each other. Due to the repulsion of like poles, a nonlinear magnetic repulsion force is generated, realizing the overall vibration of the piezoelectric device; under external vibration excitation in any direction, the water inside the elastic film causes the low-stiffness elastic film to undergo large-scale elastic deformation, thereby causing the water-impact energy harvesting unit to vibrate, and thus harvesting energy; at the same time, the spring oscillator drives permanent magnet II to move, causing the magnetic repulsion force between the two sets of permanent magnets to change, causing the upper base plate to be subjected to a nonlinear force and move, further causing the water-impact energy harvesting unit to vibrate at a higher frequency, and thus harvesting energy.

[0010] Advantages of the present invention: The bidirectional tristable vibration energy harvesting system of the present invention can solve the problems of narrow resonant frequency band, insufficient power generation, and single energy harvesting direction of the current linear elastic thin film vibration energy harvesting system. It has a simple structure and is easy to implement, and provides certain reference value for the research in the field of piezoelectric energy harvesting. Attached Figure Description

[0011] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate the invention and are used to explain it, but do not constitute an undue limitation of the invention.

[0012] Figure 1 This is a schematic diagram of the water impact energy harvesting unit structure of a water impact magnetic coupling type nonlinear piezoelectric energy harvesting device according to the present invention;

[0013] Figure 2 This is a schematic diagram of the nonlinear amplification unit structure of a water-impact magnetic coupling type nonlinear piezoelectric energy harvesting device according to the present invention;

[0014] Figure 3 This is a schematic diagram showing the relative positions of the permanent magnet II, the spring, and the fixed circular frame of the present invention;

[0015] Figure 4This is a schematic diagram illustrating the energy harvesting principle of a water-impact magnetic coupling type nonlinear piezoelectric energy harvesting device according to the present invention.

[0016] In the diagram: 1. Upper base plate; 2. Elastic film; 3. Polyvinylidene fluoride piezoelectric film; 4. Lower base plate; 5-1. Permanent magnet I; 5-2. Permanent magnet II; 6. Spring; 7. Fixed circular frame; 8. Water impact energy harvesting unit; 9. Nonlinear amplification unit. Detailed Implementation

[0017] The following description, in conjunction with the accompanying drawings, further illustrates the detailed content of the present invention and its specific embodiments.

[0018] See Figure 1 As shown, a water impact energy harvesting unit 8 of a water impact magnetic coupling type nonlinear piezoelectric energy harvesting device includes: an upper base plate 1, an elastic film 2, a polyvinylidene fluoride piezoelectric film 3, a lower base plate 4, and water placed inside the elastic film 2; the elastic film 2 is attached to the outer wall of the cylindrical surface of the concentrically mounted upper base plate 1 and lower base plate 4, forming a sealed cavity; the polyvinylidene fluoride piezoelectric film 3 is attached to the outside of the elastic film 2.

[0019] See Figure 2 and Figure 3 As shown, the nonlinear amplification unit 9 of the water-impact magnetic coupling type nonlinear piezoelectric energy harvesting device includes: two sets of permanent magnets 5, four sets of springs 6, and a fixed circular frame 7; the S pole of permanent magnet I 5-1 is fixed to the inner wall of the bottom surface of the upper base plate 1, and the S pole of permanent magnet II 5-2 faces downward. One end of the four sets of springs 6 is fixed to the geometric center of the four sides of permanent magnet II 5-2, and the other end is fixed to the inner wall of the cylindrical surface of the fixed circular frame 7. Permanent magnet II 5-2 can move relative to the lower base plate 4. The purpose is to make the N poles of the two sets of permanent magnets 5 face each other. Due to the repulsion of like poles, a nonlinear magnetic repulsion force is generated, realizing the overall vibration of the piezoelectric device.

[0020] See Figure 4As shown, the water-impact magnetic coupling type nonlinear piezoelectric energy harvesting device, under external vibration excitation in any direction, causes water inside the elastic film 2 to impact the low-stiffness elastic film 2, resulting in significant elastic deformation. This further causes the polyvinylidene fluoride piezoelectric film 3 attached to the outside of the elastic film 2 to undergo elastic deformation and harvest energy. Simultaneously, the external excitation drives the spring 6 to undergo simple harmonic motion. The spring 6 drives the permanent magnet II 5-2 fixed to it to move, causing the N poles of permanent magnet I 5-1 and permanent magnet II 5-2 to be offset. The magnetic repulsion between the two sets of permanent magnets 5 decreases, causing the upper base plate 1 fixed to permanent magnet I 5-1 to change from a gravity-magnetic equilibrium state to an unstable state where gravity is greater than magnetic force. This causes the plate to move downwards, thereby driving the water inside the elastic film 2 to impact the elastic film 2, further causing the polyvinylidene fluoride piezoelectric film 3 to undergo elastic deformation and harvest energy. The polyvinylidene fluoride piezoelectric film 3 is not only affected by the water impact unit 8 but also by the nonlinear amplification unit 9, resulting in significant deformation and energy harvesting.

[0021] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made to the present invention should be included within the scope of protection of the present invention.

Claims

1. A water-impact magnetic coupling type nonlinear piezoelectric energy harvesting device, characterized in that: include: The upper base plate (1), elastic film (2), polyvinylidene fluoride piezoelectric film (3), lower base plate (4), permanent magnet (5), spring (6), and fixed circular frame (7) are used. The elastic film (2) is pasted on the outer wall of the cylindrical surface of the concentrically mounted upper base plate (1) and lower base plate (4) to form a closed cavity. The polyvinylidene fluoride piezoelectric film (3) is pasted on the outside of the elastic film (2). The upper base plate (1), elastic film (2), polyvinylidene fluoride piezoelectric film (3), lower base plate (4), and water placed inside the elastic film (2) constitute a water impact energy harvesting unit (8). The permanent magnet (5), four sets of springs (6), and fixed circular frame (7) constitute a nonlinear amplification unit (9), wherein the S pole of the permanent magnet I (5-1) is fixed to the upper base plate (1). At the bottom inner wall, the S pole of permanent magnet II (5-2) faces downward. One end of the four sets of springs (6) is fixed to the geometric center of the four sides of permanent magnet II (5-2), and the other end is fixed to the inner wall of the cylindrical surface of the fixed circular frame (7). Permanent magnet II (5-2) can move relative to the bottom plate (4). Under external vibration excitation in any direction, the water inside the elastic film (2) causes the low stiffness elastic film (2) to undergo large elastic deformation, thereby causing the water to impact the energy-harvesting unit (8) to become elastic and thus harvest energy. At the same time, the spring (6) drives permanent magnet II (5-2) to move, causing the magnetic repulsion between the two sets of permanent magnets (5) to change, causing the upper bottom plate (1) to be stressed and move, further causing the water to impact the energy-harvesting unit (8) to undergo large deformation and thus harvest energy.

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