Multi-directional water impact frequency-up piezoelectric energy harvesting device and method

Abstract

This invention discloses a multi-directional water-impact frequency-upgrading piezoelectric energy harvesting device and method, belonging to the field of piezoelectric material energy harvesting control. The device includes: an outer frame, a cantilever base plate, a piezoelectric sheet, a mass block, a cylindrical water tank, and an elastic film. One end of the cantilever base plate is fixed to the inner side wall of the outer frame, and the other end is fixed to the mass block. The piezoelectric sheet is attached to the cantilever base plate to form a low-frequency drive system. The bottom end of the cylindrical water tank is fixed to the lower surface of the outer frame, and the elastic film is attached to the cavity at the top of the cylindrical water tank to form a high-frequency piezoelectric system. Under external low-frequency vibration excitation, the low-frequency drive system, which has a lower natural frequency, resonates, greatly increasing the vibration amplitude of the water tank. This causes the water in the water tank to continuously and significantly impact the high-frequency piezoelectric system, achieving the purpose of frequency upgrading. This invention utilizes water impact to drive the high-frequency piezoelectric beam to upgrade its frequency, improving the energy harvesting efficiency and output power of the piezoelectric energy harvesting device. Simultaneously, it has advantages such as simple production and assembly, being environmentally friendly and pollution-free, and having a miniaturized structure.

Description

Technical Field

[0001] This invention relates to a piezoelectric energy harvesting device, and more particularly to a multi-directional water impact frequency-upgrading piezoelectric energy harvesting device and method, belonging to the field of piezoelectric material energy harvesting control. Background Technology

[0002] Currently, there are three methods for converting mechanical energy into electrical energy: electrostatic energy harvesting, electromagnetic energy harvesting, and piezoelectric energy harvesting. However, electrostatic energy harvesting requires an initial voltage for power supply 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] Currently, conventional piezoelectric energy harvesters have a high natural frequency, while the surrounding environment has a low vibration frequency, making it impossible for the energy harvester to resonate and significantly reducing the output power. Existing frequency-upgrading piezoelectric devices are mainly collision-type, utilizing the collision between a low-frequency vibrating drive beam and a piezoelectric beam to increase the excitation frequency, causing the piezoelectric beam to vibrate at high frequency and generate electrical energy. This can reduce the excitation environment that the energy harvester can adapt to to some extent, but the overall structure can still only adapt to a large excitation frequency. In weak vibration environments, the energy harvesting efficiency is not high, and there is also the problem of the vibration direction being unable to be adjusted. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-directional water-impact frequency-upgrading piezoelectric energy harvesting device, which aims to solve the problems of low output power, low energy harvesting efficiency, and inability to adjust vibration direction of traditional piezoelectric energy harvesting devices. It has the advantages of simple production and assembly, green and pollution-free operation, and strong environmental adaptability.

[0005] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0006] A multi-directional water-impact frequency-upgrading piezoelectric energy harvesting device is characterized by comprising: an outer frame, an arched cantilever beam, a piezoelectric sheet, a mass block, a water storage tank, and an elastic film; one end of the arched cantilever beam is fixed to the inner wall of the side of the outer frame, and the other end is fixedly connected to the mass block; a piezoelectric sheet with a shape similar to the arched cantilever beam is pasted on the arched cantilever beam to form a high-frequency piezoelectric beam; the bottom end of the water storage tank is fixed to the bottom surface of the outer frame; and the elastic film is pasted on the cavity of the cylindrical surface of the water storage tank.

[0007] The multi-directional water-impact frequency-upgrading piezoelectric energy harvesting device is characterized by: a water tank and an elastic membrane constituting a low-frequency drive system, i.e., a frequency-upgrading system; the water tank consists of three parts: two sets of equal-thickness upper circular and lower rectangular boxes on both sides, the lower rectangular height of which is slightly larger than the radius of the upper circular box; a rectangular cavity in the middle that is fixed to the lower rectangular parts of the two side boxes, and the external cross-sectional shape of the cavity is the same as that of the rectangular part of the box; and a cylindrical cavity formed in the upper middle part, with the overall shape resembling a U-shape. The elastic membrane is attached to the cylindrical cavity of the water tank. The purpose is to enable the low-frequency drive system to adapt to multi-directional external excitation and generate multi-directional vibration energy after forced vibration; at the same time, the height dimension of the water tank is much smaller than its length dimension, so as to ensure that the natural frequency of the low-frequency drive system is lower than the natural frequency of the arched cantilever beam, so that resonance can be generated at a lower external vibration frequency.

[0008] The multi-directional water impact frequency-upgrading piezoelectric energy harvesting device is characterized in that: the water storage tank must be installed concentrically with the arched piezoelectric beam, in order to ensure that the impact frequency-upgrading mechanism has equal amplitude water impact with the arched suspended piezoelectric beam in multiple directions, and to ensure that the arched piezoelectric beam collects multi-directional vibration energy.

[0009] The energy harvesting method of this unidirectional water-impact frequency-upgrading piezoelectric energy harvesting device is as follows:

[0010] Mode 1: When the external environment vibrates unidirectionally at low frequency along the vibration direction of the arched cantilever beam, the external environment directly drives the water tank and elastic membrane to vibrate at the same frequency. The water tank and elastic membrane constitute a low-frequency drive system. Because the low-frequency drive system has a low natural frequency, it resonates with the external environment.

[0011] The resonance of the low-frequency drive system significantly increases the vibration amplitude of the water tank, causing the water inside the tank to continuously and dramatically impact the elastic membrane in multiple directions, resulting in multi-directional large-amplitude elastic deformation. This, in turn, leads to continuous multi-directional water impact with the high-frequency piezoelectric system. Therefore, the vibration frequency of the high-frequency piezoelectric system is increased, thus achieving the goal of frequency upscaling.

[0012] An arched cantilever beam, a piezoelectric element, and a mass block constitute a high-frequency piezoelectric system. This system is subjected not only to external excitation but also to multidirectional water impacts from a low-frequency drive system, thus achieving resonance. The piezoelectric element, because it is attached to the fixed end of the arched cantilever beam, possesses significant strain and converts vibrational energy into electrical energy output based on its own positive piezoelectric effect.

[0013] Mode 2: When the external environment vibrates in multiple directions at low frequencies, the water tank captures the multi-directional vibration energy of the external environment and vibrates at the same frequency. The water tank and the elastic membrane constitute a low-frequency drive system. Because the low-frequency drive system has a low natural frequency, it resonates with the external environment.

[0014] The resonance of the low-frequency drive system greatly increases the vibration amplitude of the water tank, causing the water in the water tank to continuously and significantly impact the elastic membrane, thereby converting the multi-directional vibration energy of the outside into multi-directional and large-amplitude water impacts. The water tank continuously and significantly impacts the high-frequency piezoelectric system, causing it to increase its frequency.

[0015] An arched cantilever beam, a piezoelectric element, and a mass block constitute a high-frequency piezoelectric system. This system is subjected not only to external excitation but also to multidirectional water impacts from a low-frequency drive system, thus achieving resonance. The piezoelectric element, because it is attached to the fixed end of the arched cantilever beam, possesses significant strain and converts vibrational energy into electrical energy output based on its own positive piezoelectric effect. Attached Figure Description

[0016] 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.

[0017] Figure 1 This is a schematic diagram of the overall appearance structure of a multi-directional water impact frequency-upgrading piezoelectric energy harvesting device according to the present invention;

[0018] Figure 2 This is a schematic diagram of the arched piezoelectric beam structure of a multi-directional water impact frequency-upgrading piezoelectric energy harvesting device according to the present invention;

[0019] Figure 3 This is a schematic diagram of the low-frequency drive system structure of a multi-directional water impact frequency-upgrading piezoelectric energy harvesting device according to the present invention;

[0020] Figure 4 This is a schematic diagram of the vibration configuration of a multi-directional water impact frequency-upgrading piezoelectric energy harvesting device under multi-directional or Z-directional unidirectional external excitation according to the present invention.

[0021] In the diagram: 1. Outer frame; 2. Arched cantilever beam; 3. Piezoelectric sheet; 4. Mass block; 5. Water tank; 6. Elastic membrane.

[0022] The distances or dimensions between parts have been exaggerated or reduced to show their positions; the diagram is for illustrative purposes only. Detailed Implementation

[0023] The following description, in conjunction with the accompanying drawings, further illustrates the detailed content of the present invention and its specific embodiments.

[0024] Let the X direction be the length direction, the Y direction be the width direction, the Z direction be the height direction, and a certain direction in the XZ plane be the radius direction.

[0025] See Figures 1 to 3As shown, a multi-directional water impact frequency-upgrading piezoelectric energy harvesting device includes an outer frame 1, an arched cantilever beam 2, a piezoelectric sheet 3, a mass block 4, a water storage tank 5, and an elastic film 6. One end of the arched cantilever beam 2 is fixed to the inner side wall of the outer frame 1, and the other end is fixed to the mass block 4. The piezoelectric sheet 3, which is similar in shape to the arched cantilever beam 2, is pasted on the arched cantilever beam 2 to form a high-frequency piezoelectric beam. The bottom end of the water storage tank 5 is fixed to the bottom surface of the outer frame 1, and the elastic film 6 is pasted on the cylindrical cavity of the water storage tank 5 to form a low-frequency drive system.

[0026] The arched cantilever beam 2 is a symmetrical structure about the YZ plane, with a hollow cylindrical structure in the middle and the diameter of the cylinder being about two-thirds of the length of the arched cantilever beam 2 in the X direction.

[0027] The water tank 5 and the elastic membrane 6 constitute a low-frequency drive system, i.e., a frequency-upgrading system. The water tank 5 consists of three parts: two sets of equal-thickness upper circular and lower rectangular boxes 5-1 on both sides. The lower rectangular height of the box 5-1 is slightly larger than the radius of the upper circular part. The middle rectangular cavity 5-2 is fixed to the lower rectangular part of the two side boxes 5-1, and the external cross-sectional shape of the cavity 5-2 is the same as that of the rectangular part of the box 5-1. A cylindrical cavity 5-3 is formed in the upper middle part. In the YZ plane, the whole shape is similar to a concave character. The elastic membrane 6 is pasted on the cylindrical cavity 5-3 of the water tank 5. The purpose is to enable the low-frequency drive system to adapt to multi-directional external excitation and generate multi-directional vibration energy after forced vibration. At the same time, the height dimension of the water tank 5 in the Z direction is much smaller than the length dimension in the X direction. The purpose is to ensure that the natural frequency of the low-frequency drive system is lower than the natural frequency of the arched cantilever beam 2, so that resonance can be generated at a lower external vibration frequency.

[0028] See Figure 4 As shown, a method for capturing energy using a multi-directional water-impact frequency-upgrading piezoelectric energy harvesting device is as follows:

[0029] Mode 1: When the external environment vibrates at a low frequency along the Z direction, the external environment directly drives the water tank 5 and the elastic membrane 6 to vibrate at the same frequency. The water tank 5 and the elastic membrane 6 constitute a low-frequency drive system. Because the low-frequency drive system has a low natural frequency, it resonates with the external environment.

[0030] The resonance of the low-frequency drive system greatly increases the vibration amplitude of the water tank 5, causing the water inside the tank 5 to continuously and significantly impact the elastic membrane 6 in multiple directions, resulting in multi-directional large-amplitude elastic deformation. This leads to continuous multi-directional water impact with the high-frequency piezoelectric system. Therefore, the vibration frequency of the high-frequency piezoelectric system is increased, thus achieving the purpose of frequency upscaling.

[0031] The arched cantilever beam 2, piezoelectric sheet 3, and mass block 4 constitute a high-frequency piezoelectric system. This system is subjected not only to external Z-axis excitation but also to multi-directional water impact from a low-frequency drive system, thus achieving resonance. The piezoelectric sheet 3, being attached to the fixed end of the arched cantilever beam 2, possesses a large strain and converts vibrational energy into electrical energy output based on its own positive piezoelectric effect.

[0032] Mode 2: When the external environment vibrates in multiple directions at low frequencies, the water tank 5 captures the multi-directional vibration energy and vibrates at the same frequency. The water tank 5 and the elastic membrane 6 constitute a low-frequency drive system. Because the low-frequency drive system has a low natural frequency, it resonates with the external environment.

[0033] The resonance of the low-frequency drive system greatly increases the vibration amplitude of the water tank 5, causing the water inside the water tank 5 to continuously and significantly impact the elastic film 6 attached to the cylindrical cavity 5-3 of the water tank 5, thereby converting the multi-directional vibration energy of the outside into multi-directional large-amplitude water impacts. The water tank 5 continuously and significantly impacts the high-frequency piezoelectric system, causing it to increase its frequency.

[0034] The arched cantilever beam 2, the piezoelectric sheet 3, and the mass block 4 constitute a high-frequency piezoelectric system. This system is not only subjected to external excitation but also to multi-directional water impact from the low-frequency drive system, thus achieving resonance. The piezoelectric sheet 3, being attached to the fixed end of the arched cantilever beam 2, has a large strain and converts vibration energy into electrical energy output based on its own positive piezoelectric effect.

[0035] 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 multi-directional water-impact frequency-upgrading piezoelectric energy harvesting device, characterized in that: The system includes an outer frame (1), an arched cantilever beam (2), a piezoelectric sheet (3), a mass block (4), a water tank (5), and an elastic membrane (6). One end of the arched cantilever beam (2) is fixed to the inner side wall of the outer frame (1), and the other end is fixed to the mass block (4). The piezoelectric sheet (3), which has a similar structure to the arched cantilever beam (2), is pasted on the arched cantilever beam (2). The bottom end of the water tank (5) is fixed to the bottom surface of the outer frame (1), and the elastic membrane (6) is pasted on the cylindrical cavity ((5-3)) of the water tank (5). The water tank (5) consists of three parts: two sets of equal thickness upper and lower circular sections on both sides. The square box (5-1) has a rectangular lower part with a height in the Z direction that is slightly greater than the radius of the upper circle. The rectangular cavity (5-2) in the middle is fixed to the lower rectangular part of the two side boxes (5-1), and the external cross-sectional shape of the cavity (5-2) is the same as that of the rectangular part of the box (5-1). A cylindrical cavity (5-3) is formed in the upper middle part. The overall shape in the YZ plane is similar to a concave shape. The elastic film 6 is pasted on the cylindrical cavity (5-3) of the water storage tank (5). The purpose is to enable the low-frequency drive system to adapt to multi-directional external excitation and generate multi-directional vibration energy after forced vibration. At the same time, the height dimension of the water storage tank (5) in the Z direction is much smaller than the length dimension in the X direction. The purpose is to ensure that the natural frequency of the low-frequency drive system is lower than the natural frequency of the arched cantilever beam 2, so that it can resonate at a lower external vibration frequency.

2. The energy harvesting method of a multi-directional water-impact frequency-upgrading piezoelectric energy harvesting device according to claim 1, characterized in that: When the external environment vibrates at a low frequency in the Z direction, the external environment directly drives the water tank (5) to vibrate at the same frequency. Due to its low natural frequency, it resonates with the external environment, causing the vibration amplitude of the water tank (5) to increase significantly. This causes the water in the water tank (5) to continuously impact the elastic membrane (6) in multiple directions, resulting in significant elastic deformation. Consequently, the water in the water tank (5) impacts the arched cantilever beam (2) in multiple directions, achieving the purpose of raising the frequency. The arched cantilever beam (2) is not only excited by the external Z direction but also by the multi-directional impact excitation of the water in the water tank (5), thus achieving resonance. When the external environment vibrates at a low frequency in multiple directions, the water tank (5) 5) The external multi-directional vibration energy is captured and vibrates at the same frequency. Due to its low natural frequency, it resonates with the external environment, which greatly increases the vibration amplitude of the water tank (5). This causes the water in the water tank (5) to continuously and significantly impact the elastic film (6) attached to the cylindrical cavity (5-3) of the water tank (5), thereby converting the external multi-directional vibration energy into multi-directional large-amplitude water impact. The water tank (5) continuously and significantly impacts the arched cantilever beam (2), causing it to increase its frequency. The arched cantilever beam (2) is not only subjected to external Z-direction excitation, but also to multi-directional water impact from the water tank (5), thus achieving resonance.

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