Magnetic coupling type wideband piezoelectric energy harvesting device

Abstract

This invention discloses a magnetically coupled broadband 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 permanent magnet, an L-shaped cantilever beam piezoelectric vibrator, and a lower base plate. The elastic film is adhered to the outer wall of the concentrically mounted upper and lower base plates. 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 upper base plate, and the N pole of the permanent magnet II is fixed to the lower base plate. One end of the L-shaped cantilever beam is fixed to the lower base plate, and the other end is fixed to the permanent magnet III. Four sets of piezoelectric plates are symmetrically adhered to both sides of the fixed end and the cantilever end of the L-shaped cantilever beam. The N pole of the permanent magnet III faces upward and the S pole faces downward, the purpose of which is to make the magnetic poles of permanent magnets I and II repel each other with the permanent magnet III, generating a nonlinear magnetic repulsion force. This invention solves the problem of the narrow resonant frequency band of current linear cantilever beam energy harvesting devices and achieves multi-directional energy harvesting through a cylindrical elastic film.

Description

Technical Field

[0001] This invention relates to a piezoelectric energy harvesting device, and more particularly to a magnetically coupled broadband piezoelectric energy harvesting device, belonging to the field of piezoelectric material energy harvesting and 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] Conventional piezoelectric energy harvesters are mostly curved cantilever beam structures, which can only collect the energy generated by the deformation of the cantilever beam in the bending direction, resulting in low energy harvesting efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a magnetically coupled broadband piezoelectric energy harvesting device, which aims to solve the problems of narrow energy harvesting bandwidth, low energy harvesting efficiency, and 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 magnetically coupled broadband piezoelectric energy harvesting device, characterized in that it comprises: an upper base plate, an elastic film, a polyvinylidene fluoride piezoelectric film, an L-shaped cantilever beam piezoelectric vibrator, a permanent magnet, and a lower base plate;

[0008] The magnetic coupling type broadband piezoelectric energy harvesting device is characterized in that: the elastic film is pasted on the outer wall of the concentrically mounted upper and lower base plates, and the polyvinylidene fluoride piezoelectric film is pasted on the outside of the elastic film to form a first energy harvesting unit; the IS pole of the permanent magnet is fixedly connected to the upper base plate, and the N pole of the II permanent magnet is fixedly connected to the lower base plate.

[0009] The magnetic coupling type broadband piezoelectric energy harvesting device is characterized in that: the L-shaped cantilever beam piezoelectric vibrator, i.e. the second energy harvesting unit, includes an L-shaped cantilever beam, piezoelectric sheets, and permanent magnet III; one end of the L-shaped cantilever beam is fixed to the inner wall of the lower base plate, and the other end is fixedly connected to permanent magnet III. The N pole of permanent magnet III faces upward and the S pole faces downward, and it is installed concentrically with permanent magnets I and II. The purpose is to make the magnetic poles of permanent magnet III repel each other with permanent magnets I and II, generating a nonlinear magnetic repulsion force. Four sets of piezoelectric sheets are symmetrically pasted on both sides of the fixed end and the cantilever end of the L-shaped cantilever beam. Attached Figure Description

[0010] 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.

[0011] Figure 1 This is a cross-sectional view of the overall structure of a magnetically coupled broadband piezoelectric energy harvesting device according to the present invention;

[0012] Figure 2 This is a schematic diagram of the first energy harvesting unit structure of a magnetically coupled broadband piezoelectric energy harvesting device according to the present invention;

[0013] Figure 3 This is a schematic diagram of the L-shaped cantilever beam piezoelectric vibrator structure of a magnetically coupled broadband piezoelectric energy harvesting device according to the present invention;

[0014] Figure 4 This is a schematic diagram of the energy harvesting method in a specific embodiment 1 of the magnetic coupling type broadband piezoelectric energy harvesting device of the present invention;

[0015] Figure 5 This is a schematic diagram of the energy harvesting method in a specific embodiment 2 of the magnetically coupled broadband piezoelectric energy harvesting device of the present invention.

[0016] Figure 6 This is a schematic diagram of a multi-directional energy harvesting device for a magnetically coupled broadband piezoelectric energy harvesting device according to the present invention;

[0017] In the diagram: 1. Upper base plate; 2. Elastic film; 3. Polyvinylidene fluoride piezoelectric film; 4-1. Permanent magnet I; 4-2. Permanent magnet II; 5-1. L-shaped cantilever beam; 5-2. Piezoelectric sheet; 5-3. Permanent magnet III; 6. Lower base plate. Detailed Implementation

[0018] The following description, in conjunction with the accompanying drawings, further illustrates the detailed content of the present invention and its specific embodiments.

[0019] See Figure 1 and Figure 2As shown, a magnetically coupled broadband piezoelectric energy harvesting device includes: an upper base plate 1, an elastic film 2, a polyvinylidene fluoride piezoelectric film 3, a permanent magnet 4, an L-shaped cantilever beam piezoelectric vibrator 5, and a lower base plate 6; the upper base plate 1 and the lower base plate 6 are concentrically installed, the elastic film 2 is pasted on the outer wall of the cylindrical surface of the upper base plate 1 and the lower base plate 6, and the polyvinylidene fluoride piezoelectric film 3 is pasted on the outside of the elastic film 2; the upper base plate 1, the elastic film 2, the polyvinylidene fluoride piezoelectric film 3, the lower base plate 6, and the water placed inside the elastic film 2 constitute the first energy harvesting unit 7; the S pole of the permanent magnet I4-1 is fixedly connected to the upper base plate 1, and the N pole of the permanent magnet II4-2 is fixedly connected to the lower base plate 6.

[0020] See Figure 1 and Figure 3 As shown, the L-shaped cantilever beam piezoelectric vibrator 5, i.e. the second energy harvesting unit, includes an L-shaped cantilever beam 5-1, piezoelectric plates 5-2, and permanent magnet III 5-3. One end of the L-shaped cantilever beam 5-1 is fixed to the lower base plate 6, and the other end is fixed to the permanent magnet III 5-3. The N pole of the permanent magnet III 5-3 faces upward and the S pole faces downward. The permanent magnets I 4-1, II 4-2, and III 5-3 are installed with the same center, so that the permanent magnet III 5-3 and the permanent magnet 4 repel each other and generate a nonlinear magnetic repulsion force. The four sets of piezoelectric plates 5-2 are symmetrically pasted on both sides of the fixed end and the cantilever end of the L-shaped cantilever beam 5-1.

[0021] See Figure 4 As shown, the energy harvesting method of specific embodiment 1 is as follows: Under arbitrary external vibration excitation, water placed inside the elastic film 2 vibrates at the same frequency, impacting the low-stiffness elastic film 2 attached to the outer wall, causing the elastic film 2 to undergo large elastic deformation, causing the polyvinylidene fluoride piezoelectric film 3 attached to the outside of the elastic film 2 to deform, and the first energy harvesting unit 7 directly harvests energy; further, the water impact causes the upper bottom plate 1, which is fixed to the elastic film 2, to generate a negative Z-direction displacement, causing the relative distance between the permanent magnet I4-1 and the permanent magnet III5-3, which are fixed to it, to change, generating a changing nonlinear magnetic repulsion force, thereby causing the high-stiffness L-shaped cantilever beam 5-1 to generate a relatively large negative Z-direction displacement, causing the relative distance between the permanent magnet III5-3 and the permanent magnet II4-2 to change, generating a changing nonlinear magnetic repulsion force, thereby causing the high-stiffness L-shaped cantilever beam 5-1 to generate a relatively large positive Z-direction displacement, causing the L-shaped cantilever beam 5-1 to vibrate at high frequency, and the second energy harvesting unit up-frequency harvests energy to achieve the purpose of broadband.

[0022] See Figure 5As shown, the energy harvesting method of specific embodiment 2 is as follows: Under Z-direction external vibration excitation, the second energy harvesting unit drives the permanent magnet III5-3 to vibrate at the same frequency, causing the relative distance between the permanent magnet III5-3 and the permanent magnets I4-1 and II4-2 to change, generating a changing nonlinear magnetic repulsion force, which causes the upper base plate 1 fixed to the permanent magnet 4 to produce Z-direction displacement, further causing the low-stiffness elastic film 2 to undergo large elastic deformation, and the first energy harvesting unit 7 achieves energy harvesting; at the same time, the large elastic deformation of the elastic film 2 causes the water placed in the elastic film 2 to vibrate, thereby causing the second energy harvesting unit to harvest energy at a higher frequency, achieving the broadband purpose.

[0023] See Figure 6 As shown, a magnetically coupled broadband piezoelectric energy harvesting device, under external vibration excitation, water placed inside the elastic film 2 causes the cylindrical elastic film 2 to expand in multiple directions in the XY plane, driving the polyvinylidene fluoride piezoelectric film 3 attached to the outside of the elastic film 2 to vibrate in multiple directions and harvest energy; on the other hand, the changing relative positions between permanent magnets I4-1 and II4-2 and permanent magnet III5-3 generate changing magnetic repulsion, driving the movable upper base plate 1 to produce positive and negative Z-direction displacement, thereby realizing the multi-directional compression and expansion of the elastic film 2 in the XY plane, and further realizing the multi-directional vibration and energy harvesting of the polyvinylidene fluoride piezoelectric film 3.

[0024] 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 magnetically coupled broadband piezoelectric energy harvesting device, characterized in that: include: The upper base plate (1), elastic film (2), polyvinylidene fluoride piezoelectric film (3), permanent magnet (4), L-shaped cantilever beam piezoelectric vibrator (5), and lower base plate (6) are used. The elastic film (2) is pasted on the outer wall of the cylindrical surface of the concentrically installed upper base plate (1) and lower base plate (6), and 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 (6), and water placed inside the elastic film (2) constitute the first energy-harvesting unit (7). The S pole of the permanent magnet I (4-1) is fixedly connected to the upper base plate (1), and the N pole of the permanent magnet II (4-2) is fixedly connected to the lower base plate (6). The L-shaped cantilever beam piezoelectric vibrator (5), i.e. the second energy-harvesting unit, includes an L-shaped cantilever beam (5-1), a piezoelectric sheet (5-2), and a permanent magnet III (5-3). One end of the L-shaped cantilever beam (5-1) is fixedly connected to the lower base plate (6). The bottom plate (6) is fixed to the inner wall of the bottom plate (6), and the other end is fixed to the permanent magnet III (5-3). The N pole of the permanent magnet III (5-3) is facing up and the S pole is facing down. Four sets of piezoelectric sheets (5-2) are symmetrically pasted on the fixed end and the cantilever end of the L-shaped cantilever beam (5-1) respectively. The permanent magnet I (4-1), permanent magnet II (4-2) and permanent magnet III (5-3) are installed at the same center. Under any external vibration excitation, the water inside the elastic film (2) causes the low stiffness elastic film (2) to undergo large elastic deformation, and the first energy-harvesting unit (7) directly harvests energy. The deformed elastic film (2) causes the distance and relative position between the permanent magnet I (4-1), permanent magnet II (4-2) and permanent magnet III (5-3) to change, which drives the permanent magnet (4) and permanent magnet III (5-3) to generate a changing magnetic repulsion force, causing the high stiffness L-shaped cantilever beam (5-1) to generate nonlinear vibration, and then the second energy-harvesting unit harvests energy.

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