Multi-degree-of-freedom wideband piezoelectric vibration energy harvesting device

Abstract

The application provides a multi-degree-of-freedom wide-frequency piezoelectric vibration energy harvesting device, and relates to the field of piezoelectric energy harvesting. The multi-degree-of-freedom wide-frequency piezoelectric vibration energy harvesting device comprises a main base, an arched cantilever beam, a rotating structure and a magnetic assembly. One end of the arched cantilever beam is connected with the main base, and an arched piezoelectric element is arranged on the surface of the arched cantilever beam. The rotating structure comprises a rotating seat and an elastic reset member. The rotating axis of the rotating seat is perpendicular to the plane where the arched cantilever beam is located. The elastic reset member is connected between the rotating seat and the arched cantilever beam. When the rotating structure rotates relative to the arched cantilever beam, the elastic reset member is in an energy storage state to generate a reset force on the rotating seat. The magnetic assembly comprises oppositely arranged first and second magnetic elements. The first magnetic element is arranged on the rotating seat, and the second magnetic element is arranged on the main base. The first and second magnetic elements form magnetic field forces with each other, thereby widening the working frequency band and energy harvesting efficiency of the device.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric energy harvesting technology, and in particular to a multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device. Background Technology

[0002] Piezoelectric vibration energy harvesting is an emerging technology that utilizes environmental vibrations to convert them into electrical energy for self-powered operation. However, since environmental vibrations are mainly low-frequency, and the operating frequency of the energy harvesting device is far from the environmental vibration frequency, the actual energy harvesting efficiency is low.

[0003] Chinese invention patent application CN103701364A, published on April 2, 2014, discloses a wind-induced vibration broadband piezoelectric power generation device. Specifically, it includes a fan, a fixed support, a rotating permanent magnet, a rotating shaft, a fixed permanent magnet, springs, a support frame, and at least two piezoelectric power generation beams. The rotating permanent magnet and the fan are fixed to the same rotating shaft. The support frame is fixed to the fixed support by four identical springs. One end of each piezoelectric power generation beam is fixed to the support frame. The fixed permanent magnet is fixed to the lower end of the support frame. Each piezoelectric power generation beam consists of a metal mass block, an elastic metal sheet, an upper piezoelectric sheet, and a lower piezoelectric sheet. The upper and lower piezoelectric sheets are respectively attached to the upper and lower surfaces of the elastic metal sheet. It utilizes wind energy from the external environment, converting it into mechanical vibration energy to generate electricity.

[0004] Existing wind-induced vibration broadband piezoelectric power generation devices can incorporate piezoelectric cantilever beams of varying sizes and parameters, thus broadening the energy harvesting bandwidth. However, in actual operation, only one or a few piezoelectric cantilever beams respond to environmental vibrations, and only specific types of environmental vibrations generate electricity, resulting in low piezoelectric energy harvesting efficiency. Furthermore, while incorporating piezoelectric cantilever beams with different parameters on the support frame can broaden the operating bandwidth, adding even more piezoelectric cantilever beams would lead to an overly complex power generation device structure. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device, which solves the problems that only one or a few piezoelectric cantilever beams respond to environmental vibrations, and that only specific types of environmental vibrations can generate electrical energy, resulting in low piezoelectric energy harvesting efficiency; in addition, setting more piezoelectric cantilever beams would lead to an overly complex structure of the power generation device.

[0006] The technical solution of the multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device of the present invention is as follows:

[0007] The multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device includes a main base, an arched cantilever beam, a rotating structure, and a magnetic component. One end of the arched cantilever beam is connected to the main base, and the rotating structure is installed at the other end of the arched cantilever beam. An arched piezoelectric element is attached to the surface of the arched cantilever beam.

[0008] The rotating structure includes a rotating seat and an elastic reset member. The rotation axis of the rotating seat is perpendicular to the plane where the arched cantilever beam is located, and the elastic reset member is connected between the rotating seat and the arched cantilever beam.

[0009] The elastic reset member has an energy storage state and a balance state. When the rotating structure remains stationary relative to the arched cantilever beam, the elastic reset member is in a balance state. When the rotating structure rotates relative to the arched cantilever beam, the elastic reset member is in an energy storage state to generate a reset force on the rotating seat.

[0010] The magnetic assembly includes a first magnetic element and a second magnetic element arranged opposite to each other. The first magnetic element is disposed on the rotating base, and the second magnetic element is disposed on the main base. The first magnetic element and the second magnetic element form a magnetic field force with each other.

[0011] Furthermore, the main base is a shell-type base, one end of the arched cantilever beam is fixedly connected to the inner wall of the shell-type base, and the rotating structure is located in the middle of the inner cavity of the shell-type base.

[0012] Furthermore, the first magnetic element and the second magnetic element are arranged with the same pole facing each other. When the rotating structure remains stationary relative to the arched cantilever beam, the magnetic repulsion force between the first magnetic element and the second magnetic element extends radially along the rotating seat.

[0013] Furthermore, a support arm is connected between the rotating base and the first magnetic element. The length direction of the support arm extends radially along the rotating base, and the first magnetic element is fixed to the end of the support arm away from the rotating base.

[0014] Furthermore, the support arm is an elastic rod structure, and a first straight piezoelectric element is attached to the surface of the support arm.

[0015] Furthermore, the outer side of the rotating base is provided with three first magnetic elements, which are circumferentially spaced about the rotating base; correspondingly, the interior of the main base is provided with three second magnetic elements, and the three second magnetic elements and their corresponding first magnetic elements respectively form a magnetic repulsion force.

[0016] Furthermore, the lines connecting the three first magnetic elements and the rotation center of the rotating seat form a T-shaped structure. When the rotating structure remains stationary relative to the arched cantilever beam, the arch span direction of the arched cantilever beam extends along the axis of symmetry of the T-shaped structure.

[0017] Furthermore, the arched cantilever beam includes a fixedly connected arc-shaped segment and a straight extension segment. The length direction of the straight extension segment is arranged along the line connecting the two ends of the arc-shaped segment. The arched piezoelectric element is attached to the upper surface of the arc-shaped segment, and the polarization direction of each position of the arched piezoelectric element points to the center of the arch.

[0018] Furthermore, the elastic reset component includes two shape memory alloy springs, which are respectively disposed on opposite sides of the arched cantilever beam.

[0019] Furthermore, an elastic clip structure is connected between the second magnetic element and the main base. A second straight piezoelectric element is stretched on the elastic clip. When the rotating structure remains stationary relative to the arched cantilever beam, the magnetic repulsion force between the first magnetic element and the second magnetic element is perpendicular to the length direction of the second straight clip element.

[0020] Beneficial Effects: This multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device adopts a design consisting of a main base, an arched cantilever beam, a rotating structure, and magnetic components. One end of the arched cantilever beam is connected to the main base, and the rotating structure is installed at the other end. Compared to a straight cantilever beam, the arched cantilever beam has a lower modal frequency, while environmental vibrations are predominantly low-frequency, effectively compensating for the frequency mismatch between a straight cantilever beam and environmental vibrations. Arched piezoelectric elements are attached to the surface of the arched cantilever beam, with the polarization direction of each element pointing towards the center of the arch. This design is not limited by the characteristic form of environmental vibrations and can be used for energy harvesting from multi-directional environmental vibrations, improving the electrical energy output of the piezoelectric elements.

[0021] Furthermore, an elastic reset component connects the arched cantilever beam and the rotating base. The first magnetic element on the rotating base and the second magnetic element on the main base are arranged opposite each other, and they generate a magnetic force with each other. When the entire device is stationary, the rotating structure remains stationary relative to the arched cantilever beam, the magnetic force between the magnetic components remains stable, and the elastic reset component is in equilibrium. The rotating structure and the magnetic components together form a triggering system with higher degrees of freedom. Once there is a slight change in the external environment, the steady state of the triggering system can be broken, inducing the rotating structure to rotate and vibrate under inertia, which in turn drives the arched cantilever beam to vibrate further, greatly widening the operating frequency band and energy harvesting efficiency of the energy harvesting device. Compared with existing power generation devices, it is not necessary to design a large number of piezoelectric cantilever beams to significantly widen the operating frequency band, and the structure of the entire energy harvesting device is simpler.

[0022] Furthermore, this multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device can be induced to undergo various modes of coherent resonance, such as parametric resonance and internal resonance, under environmental vibration. Even if the environmental vibration frequency is far from the conditional frequency of coherent resonance, the triggering system composed of the rotating structure and magnetic components will continue to vibrate under the combined action of inertial force and elastic restoring force, which further improves the operating frequency band and energy harvesting efficiency of the device, thereby breaking through the technical bottleneck that existing nonlinear power generation devices cannot significantly improve energy harvesting efficiency. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the internal structure of the multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device in a specific embodiment of the present invention.

[0024] In the figure: 1 - main base, 2 - arched cantilever beam, 20 - arched piezoelectric element, 21 - circular arc segment, 22 - straight extension segment;

[0025] 3 - Rotating structure, 30 - First straight piezoelectric element, 31 - Rotating seat, 32 - Elastic reset element, 33 - Support arm;

[0026] 4 – First magnetic element, 5 – Second magnetic element, 6 – Elastic clip structure, 60 – Second straight piezoelectric element. Detailed Implementation

[0027] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0028] Specific embodiment 1 of the multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device of the present invention, as follows: Figure 1 As shown, the multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device includes a main base 1, an arched cantilever beam 2, a rotating structure 3, and a magnetic component. One end of the arched cantilever beam 2 is connected to the main base 1, and the rotating structure 3 is installed at the other end of the arched cantilever beam 2. An arched piezoelectric element 20 is attached to the surface of the arched cantilever beam 2. The rotating structure 3 includes a rotating seat 31 and an elastic reset member 32. The rotation axis of the rotating seat 31 is perpendicular to the plane where the arched cantilever beam 2 is located, and the elastic reset member 32 is connected between the rotating seat 31 and the arched cantilever beam 2.

[0029] The elastic reset member 32 has an energy storage state and a balance state. When the rotating structure 3 remains stationary relative to the arched cantilever beam 2, the elastic reset member 32 is in a balance state. When the rotating structure 3 rotates relative to the arched cantilever beam 2, the elastic reset member 32 is in an energy storage state to generate a reset force on the rotating seat 31. The magnetic assembly includes a first magnetic element 4 and a second magnetic element 5 arranged opposite to each other. The first magnetic element 4 is disposed on the rotating seat 31, and the second magnetic element 5 is disposed on the main base 1. The first magnetic element 4 and the second magnetic element 5 form a magnetic field force with each other.

[0030] This multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device adopts a design consisting of a main base 1, an arched cantilever beam 2, a rotating structure 3, and magnetic components. One end of the arched cantilever beam 2 is connected to the main base 1, and the rotating structure 3 is installed at the other end of the arched cantilever beam 2. Compared with a straight cantilever beam, the arched cantilever beam 2 has a lower modal frequency, while environmental vibrations are mainly low-frequency, effectively compensating for the frequency mismatch between a straight cantilever beam and environmental vibrations. Arched piezoelectric elements 20 are attached to the surface of the arched cantilever beam 2. The polarization direction of each position of the arched piezoelectric element 20 points towards the center of the arch, which is not limited by the characteristic form of environmental vibrations and can be used for energy harvesting from multi-directional environmental vibrations, thereby improving the electrical energy output of the piezoelectric element.

[0031] Furthermore, an elastic reset member 32 connects the arched cantilever beam 2 and the rotating base 31. The first magnetic element 4 on the rotating base 31 and the second magnetic element 5 on the main base 1 are arranged opposite each other, and the two form a magnetic field force. When the entire device is stationary, the rotating structure 3 remains stationary relative to the arched cantilever beam 2, the magnetic force between the magnetic components remains stable, and the elastic reset member 32 is in a balanced state. The rotating structure 3 and the magnetic components together form a triggering system with higher degrees of freedom. Once the external environment changes slightly, it can break the steady state of the triggering system, inducing the rotating structure 3 to rotate under inertia, and driving the arched cantilever beam 2 to vibrate further, greatly widening the operating frequency band and energy harvesting efficiency of the energy harvesting device. Compared with existing power generation devices, it is not necessary to design a large number of piezoelectric cantilever beams to significantly widen the operating frequency band, and the structure of the entire energy harvesting device is simpler.

[0032] Furthermore, this multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device can be induced to undergo various modes of coherent resonance, such as parametric resonance and internal resonance, under environmental vibration. Even if the environmental vibration frequency is far from the conditional frequency of coherent resonance, the triggering system composed of the rotating structure 3 and the magnetic component will continue to vibrate under the combined action of inertial force and elastic reset force, which further improves the operating frequency band and energy harvesting efficiency of the device, thereby breaking through the technical bottleneck that existing nonlinear power generation devices cannot significantly improve energy harvesting efficiency.

[0033] In this embodiment, the main base 1 is a shell-type base, one end of the arched cantilever beam 2 is fixedly connected to the inner wall of the shell-type base, and the rotating structure 3 is located in the middle of the inner cavity of the shell-type base. Furthermore, the first magnetic element 4 and the second magnetic element 5 are arranged with the same pole facing each other. When the rotating structure 3 remains stationary relative to the arched cantilever beam 2, the magnetic repulsion force between the first magnetic element 4 and the second magnetic element 5 extends radially along the rotating base 31.

[0034] Specifically, the N poles of the first magnetic element 4 and the second magnetic element 5 are positioned opposite each other, creating a magnetic repulsion force between them. When the entire device is stationary, the combined force of the weight of the rotating base 31 itself, the supporting force of the arched cantilever beam 2 on the rotating base 31, the elastic force of the elastic reset member 32 on the rotating base 31, and the magnetic repulsion force between the magnetic components is zero. Therefore, both the rotating base 31 and the arched cantilever beam 2 remain stationary, and the device does not generate electrical energy. However, even a small change in the external environment can disrupt the steady state of the triggering system and further cause the arched cantilever beam 2 to vibrate.

[0035] As a further preferred embodiment, a support arm 33 is also connected between the rotating base 31 and the first magnetic element 4. The length direction of the support arm 33 extends radially along the rotating base 31, and the first magnetic element 4 is fixed to the end of the support arm 33 away from the rotating base 31. The support arm 33 is an elastic rod structure, and a first straight piezoelectric element 30 is attached to the surface of the support arm 33. By designing the support arm 33, the lever arm length between the first magnetic element 4 and the center of the rotating base 31 is increased. Under external vibration, the relative positions of the first magnetic element 4 and the second magnetic element 5 change, resulting in a larger deflection torque, ensuring that a larger amplitude rotational vibration can be generated.

[0036] Furthermore, a first straight piezoelectric element 30 is attached to the surface of the support rod 33. The support rod 33 can bend and deform as the magnetic field force changes. The deformation of the support rod 33 can cause the first straight piezoelectric element 30 to generate corresponding electrical energy, thereby increasing the piezoelectric power generation part and improving the output energy of piezoelectric vibration.

[0037] Furthermore, the outer side of the rotating base 31 is provided with three first magnetic elements 4, which are circumferentially spaced about the rotating base 31. Correspondingly, the main base 1 is a shell-type base, and the interior of the main base 1 is provided with three second magnetic elements 5, which respectively form a magnetic repulsion force with the corresponding first magnetic elements 4. The line connecting the three first magnetic elements 4 and the rotation center of the rotating base 31 forms a T-shaped structure. When the rotating structure 3 remains stationary relative to the arched cantilever beam 2, the arch span direction of the arched cantilever beam 2 extends along the axis of symmetry of the T-shaped structure.

[0038] In this embodiment, the arched cantilever beam 2 includes a fixedly connected arc-shaped segment 21 and a straight extension segment 22. The length direction of the straight extension segment 22 is arranged along the line connecting the two ends of the arc-shaped segment 21. The arched piezoelectric element 20 is attached to the upper surface of the arc-shaped segment 21, and the polarization direction of each position of the arched piezoelectric element 20 points to the center of the arch, ensuring that the arched piezoelectric element 20 has a more significant balanced polarization effect. Furthermore, the elastic reset member 32 includes two shape memory alloy springs, which are respectively disposed on opposite sides of the arched cantilever beam 2.

[0039] In addition, an elastic clamping structure 6 is connected between the second magnetic element 5 and the main base 1. A second straight piezoelectric element 60 is stretched onto the elastic clamping structure 6. When the rotating structure 3 remains stationary relative to the arched cantilever beam 2, the magnetic repulsion force between the first magnetic element 4 and the second magnetic element 5 is perpendicular to the length direction of the second straight clamping element 60. Specifically, the elastic clamping structure 6 is hexagonal in shape, and the second straight piezoelectric element 60 is divided and disposed in the middle of the hexagon. When the magnetic repulsion force of the magnetic components changes, the tensile force of the elastic clamping structure 6 on the second straight piezoelectric element 60 changes accordingly, thereby causing the second straight piezoelectric element 60 to generate corresponding electrical energy, further increasing the piezoelectric power generation section and achieving the purpose of capturing energy in multiple forms.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device, characterized in that, It includes a main base, an arched cantilever beam, a rotating structure, and a magnetic component. One end of the arched cantilever beam is connected to the main base, and the rotating structure is installed at the other end of the arched cantilever beam. An arched piezoelectric element is attached to the surface of the arched cantilever beam. The rotating structure includes a rotating seat and an elastic reset member. The rotation axis of the rotating seat is perpendicular to the plane where the arched cantilever beam is located, and the elastic reset member is connected between the rotating seat and the arched cantilever beam. The elastic reset member has an energy storage state and a balance state. When the rotating structure remains stationary relative to the arched cantilever beam, the elastic reset member is in a balance state. When the rotating structure rotates relative to the arched cantilever beam, the elastic reset member is in an energy storage state to generate a reset force on the rotating seat. The magnetic assembly includes a first magnetic element and a second magnetic element arranged opposite to each other. The first magnetic element is disposed on the rotating base, and the second magnetic element is disposed on the main base. The first magnetic element and the second magnetic element form a magnetic field force with each other.

2. The multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device according to claim 1, characterized in that, The main base is a shell-type base, one end of the arched cantilever beam is fixedly connected to the inner wall of the shell-type base, and the rotating structure is located in the middle of the inner cavity of the shell-type base.

3. The multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device according to claim 1 or 2, characterized in that, The first magnetic element and the second magnetic element are arranged with the same pole facing each other. When the rotating structure remains stationary relative to the arched cantilever beam, the magnetic repulsion force between the first magnetic element and the second magnetic element extends radially along the rotating seat.

4. The multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device according to claim 3, characterized in that, A support arm is also connected between the rotating base and the first magnetic element. The length direction of the support arm extends radially along the rotating base, and the first magnetic element is fixed to the end of the support arm away from the rotating base.

5. The multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device according to claim 4, characterized in that, The support arm is an elastic rod structure, and a first straight piezoelectric element is attached to the surface of the support arm.

6. The multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device according to claim 4, characterized in that, The outer side of the rotating base is provided with three first magnetic elements, which are circumferentially spaced about the rotating base; correspondingly, the interior of the main base is provided with three second magnetic elements, and the three second magnetic elements and their corresponding first magnetic elements form a magnetic repulsion force with each other.

7. The multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device according to claim 6, characterized in that, The lines connecting the three first magnetic elements and the rotation center of the rotating seat form a T-shaped structure. When the rotating structure remains stationary relative to the arched cantilever beam, the arch span direction of the arched cantilever beam extends along the axis of symmetry of the T-shaped structure.

8. The multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device according to claim 1 or 2, characterized in that, The arched cantilever beam includes a fixedly connected arc-shaped segment and a straight extension segment. The length direction of the straight extension segment is arranged along the line connecting the two ends of the arc-shaped segment. The arched piezoelectric element is attached to the upper surface of the arc-shaped segment, and the polarization direction of each position of the arched piezoelectric element points to the center of the arch.

9. The multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device according to claim 1 or 2, characterized in that, The elastic reset component includes two shape memory alloy springs, which are respectively disposed on opposite sides of the arched cantilever beam.

10. The multi-degree-of-freedom broadband piezoelectric vibration energy harvesting device according to claim 1 or 2, characterized in that, An elastic clip structure is also connected between the second magnetic element and the main base. A second straight piezoelectric element is stretched on the elastic clip. When the rotating structure remains stationary relative to the arched cantilever beam, the magnetic repulsion force between the first magnetic element and the second magnetic element is perpendicular to the length direction of the second straight piezoelectric element.

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