Magnetic force enhanced vibration energy collecting device and method

Abstract

The invention provides a magnetic force enhanced vibration energy collection device and method. The magnetic force enhanced vibration energy collection device comprises a piezoelectric power generation module and an electromagnetic power generation module, wherein the piezoelectric power generation module comprises a piezoelectric high-frequency beam, a metal low-frequency beam, a stop block and a first permanent magnet; the electromagnetic power generation module comprises a second permanent magnet, a coil, a magnetic conductive material and a coil shaft, the coil shaft is arranged in the coil, the magnetic conductive material is located in a center hole of the coil shaft, and the coil is arranged around the magnetic conductive material. Aiming at the problems of narrow working frequency band and low energy output of a vibration energy collector, two modes of collision frequency raising and frequency expanding and magnetic force frequency raising and frequency expanding are combined in one piezoelectric energy collecting module, and meanwhile, an electromagnetic power generation module is introduced. Therefore, the energy conversion efficiency and the overall generating capacity are improved, energy collection in the overall wide frequency range is achieved, low-frequency vibration energy with the wide change range in the environment can be effectively collected and converted into electric energy, and power is supplied to wireless sensing nodes.

Description

Technical Field

[0001] The present invention relates to the technical field of energy harvesting, and particularly relates to a magnetic force enhanced vibration energy harvesting device and method. Background Art

[0002] With the rapid development of wireless sensor networks and wearable electronic devices, the power consumption of microelectronics has been reduced to the micro-watt level. Traditional battery power supply methods have problems such as large volume, environmental pollution, and the need for regular replacement. How to provide a long-term stable energy source for microelectronic devices is a technical problem that needs to be overcome currently. There is a large amount of vibration energy in the environment, such as vibrations generated by mechanical operation, vehicle driving, human movement, air flow, etc. These vibration energies are a sustainable clean energy source. If it can be effectively harvested and converted into electrical energy, it can provide an ideal self-powered solution for low-power devices and reduce the dependence on traditional batteries. Currently, piezoelectric vibration energy harvesters are a common type of vibration energy harvesting device, which utilize the direct piezoelectric effect of piezoelectric materials to convert mechanical vibration energy into electrical energy, thereby providing long-term stable power supply for micro low-power wireless sensor network nodes.

[0003] However, traditional piezoelectric vibration energy harvesters have a key limitation, that is, their resonance frequencies are relatively fixed. The vibration frequencies in the actual environment are complex and diverse. For example, the vibration frequency of machine equipment may vary from a few hertz to several hundred hertz. When the frequency of the vibration source does not match the resonance frequency of the harvester, the energy harvesting efficiency will drop sharply, which greatly limits its application range in the actual environment. Therefore, effective measures need to be taken to broaden the working frequency band of the energy harvester and enhance its output performance, so as to accelerate the development of wireless sensor networks.

[0004] At present, there are two main working mechanisms for expanding the bandwidth and enhancing the output performance of vibration energy harvesters, namely collision up-conversion and magnetic up-conversion. The collision up-conversion mechanism of piezoelectric vibration energy harvesters is mainly divided into three stages: approach, collision and separation: in the approach state, the low-frequency beam is bent and moves upward by external excitation. Since the gap distance is smaller than the vibration amplitude of the low-frequency beam, the low-frequency beam will excite the high-frequency beam in each vibration cycle. When the low-frequency beam contacts the high-frequency beam, the high-frequency beam has a greater stiffness than the low-frequency beam, which makes the displacement amplitude of the end of the high-frequency beam much smaller than that of the low-frequency beam. Therefore, the upward movement of the end of the low-frequency beam will be constrained by the high-frequency beam, and this constraint causes the overall stiffness of the low-frequency beam to increase with the increase of displacement. As a result, the resonant frequency of the low-frequency beam gradually increases during the collision process, showing the mechanical characteristics of a nonlinear spring. This nonlinear characteristic can effectively widen the working frequency band of the collector. Afterwards, the low-frequency beam moves downward under external excitation and separates from the high-frequency beam. At the same time, the high-frequency beam is stimulated by the impact effect and oscillates at its own higher resonant frequency, thus achieving the transition from low-frequency vibration to high-frequency oscillation. However, when the external excitation intensity is low and the low-frequency beam mass block cannot contact the high-frequency beam, the high-frequency beam cannot effectively collect the external low-frequency vibration energy.

[0005] The magnetic up-conversion mechanism of the piezoelectric vibration energy harvester mainly uses magnetic interaction to broaden the working frequency band and enhance the output performance. It usually sets magnets at the ends of the high-frequency beam and the low-frequency beam to generate nonlinear forces through the magnetic field. When vibration occurs, the magnetic force changes the vibration characteristics of the system, which is equivalent to changing the equivalent stiffness of the system. According to vibration theory, the resonant frequency of the system also changes accordingly, so that it can respond to vibrations of different frequencies and achieve a widened working frequency band. Similar to the collision up-conversion mechanism, in the magnetic up-conversion mechanism, the low-frequency beam moves downward under external excitation and separates from the high-frequency beam. At the same time, the high-frequency beam is also moved by the magnetic force to oscillate at its own higher resonant frequency, realizing the transition from low-frequency vibration to high-frequency oscillation. However, the non-contact magnetic force of the magnetic up-conversion mechanism excites the high-frequency beam less than the contact mechanical impact of the collision up-conversion mechanism on the high-frequency beam. In addition, the working frequency band width of the magnetic up-conversion mechanism is also narrower than that of the collision up-conversion mechanism. Therefore, the energy collection efficiency of the magnetic up-conversion mechanism is relatively low.

[0006] The common problems existing in current vibration energy harvesting mainly include low energy conversion efficiency, small power generation, narrow working frequency band, and poor environmental adaptability, which need to be further improved. Traditional linear energy harvesters have only a single natural frequency, and their amplitude-frequency response curves are very narrow. In the actual environment, the vibration frequencies are complex and variable. Once the external excitation frequency does not match the natural frequency, the output power will be greatly reduced, resulting in most of the vibration energy being unable to be effectively harvested. The output impedance of piezoelectric materials is relatively large, and the dielectric loss is relatively high. In a low-frequency vibration environment, the efficiency of piezoelectric energy harvesters in converting mechanical energy into electrical energy is not high, making it difficult to meet the power consumption requirements of low-power devices such as wireless sensors. Although it is found that there are various mechanisms that can broaden the working frequency band of vibration energy harvesters and enhance the output performance, there are deficiencies in all of them. For example, the collision frequency-up conversion and frequency broadening mechanism has certain requirements for the excitation intensity of external vibrations, and the working frequency band width of the magnetic force frequency-up conversion and frequency broadening mechanism is relatively narrow and the energy harvesting efficiency is relatively low. How to integrate multiple mechanisms in a device to make up for each other's advantages and further improve the vibration energy harvesting and conversion efficiency is a technical problem to be solved. Summary of the Invention

[0007] The object of the present invention is achieved through the following technical solutions.

[0008] In view of the problems of narrow working frequency band and low energy output of vibration energy harvesters, the present invention combines two methods of collision frequency-up conversion and magnetic force frequency-up conversion in a piezoelectric energy harvesting module, and at the same time introduces an electromagnetic power generation module. Thereby improving the energy conversion efficiency and overall power generation, realizing energy harvesting in the overall wide frequency range, effectively harvesting low-frequency and wide-range vibration energy in the environment and converting it into electrical energy to power wireless sensing nodes.

[0009] According to the first aspect of the present invention, a magnetic force enhanced vibration energy harvesting device is provided, including:

[0010] A piezoelectric power generation module and an electromagnetic power generation module; wherein,

[0011] The piezoelectric power generation module includes a piezoelectric high-frequency beam, a metal low-frequency beam, a stopper, and a first permanent magnet;

[0012] The electromagnetic power generation module includes a second permanent magnet, a coil, a magnetic conductive material, and a coil shaft. The coil shaft is disposed inside the coil, the magnetic conductive material is located in the central hole of the coil shaft, and the coil is disposed around the magnetic conductive material.

[0013] Further, the piezoelectric high-frequency beam is made of a flexible metal material with elasticity and no magnetism as the substrate, and is prepared by laminating a piezoelectric material as the power generation layer on the metal substrate. One end of the piezoelectric high-frequency beam is fixed, and the other end can move freely;

[0014] A first permanent magnet is fixed to the lower surface of the free end of the piezoelectric high-frequency beam, and the polarization direction of the first permanent magnet is perpendicular to the surface of the piezoelectric high-frequency beam.

[0015] Furthermore, the metal low-frequency beam is made of an elastic and non-magnetic metal material; one end of the metal low-frequency beam is fixed, and the other end can move freely;

[0016] A second permanent magnet is fixed on the upper surface of the free end of the metal low-frequency beam, and the polarization direction of the second permanent magnet is perpendicular to the surface of the metal low-frequency beam.

[0017] Furthermore, the stopper is made of a photosensitive resin material and is adhered to the second permanent magnet; and the relative magnetic poles of the first permanent magnet and the second permanent magnet have opposite magnetic properties.

[0018] Furthermore, the coil is wound by enameled copper wire and fixed on a coil shaft inside the coil.

[0019] Furthermore, the magnetic conductive material is composed of stacked sheets of high magnetic conductive material, and the magnetic conductive material is fixed in a through hole at the center of the coil axis and is placed at a certain distance from the second permanent magnet.

[0020] According to a second aspect of the present invention, there is also provided a magnetically enhanced vibration energy collection method using the device, comprising:

[0021] When the metal low-frequency beam is excited by external low-frequency vibration, the metal low-frequency beam drives the second permanent magnet and the stopper at the end to vibrate up and down;

[0022] When the external vibration excitation acceleration is large, the block collides with the first permanent magnet under the piezoelectric high-frequency beam, causing the piezoelectric layer on the piezoelectric high-frequency beam to deform significantly, and charges with opposite polarities accumulate on the upper and lower surfaces of the piezoelectric layer, and the piezoelectric power generation module generates electricity;

[0023] When the external vibration excitation acceleration is small, the block does not collide with the first permanent magnet under the piezoelectric high-frequency beam. The second permanent magnet on the metal low-frequency beam moves the first permanent magnet under the piezoelectric high-frequency beam through magnetic attraction, causing the piezoelectric layer on the piezoelectric high-frequency beam to deform, thereby collecting low-frequency vibration energy.

[0024] Furthermore, when the external vibration excitation acceleration is large, the block collides with the first permanent magnet under the piezoelectric high-frequency beam, causing the piezoelectric layer on the piezoelectric high-frequency beam to deform significantly, and charges with opposite polarities accumulate on the upper and lower surfaces of the piezoelectric layer. The piezoelectric power generation module generates electricity, including:

[0025] A collision cycle process is divided into three stages, including approach stage, collision stage and separation stage;

[0026] In the approaching stage, the metal low-frequency beam bends and moves upward due to external excitation. Since the gap distance is smaller than the vibration amplitude of the metal low-frequency beam, the metal low-frequency beam collides with the piezoelectric high-frequency beam in each vibration cycle.

[0027] In the collision stage, when the metal low-frequency beam contacts the piezoelectric high-frequency beam, the upward movement of the end of the metal low-frequency beam is constrained by the piezoelectric high-frequency beam, and the constraint causes the overall stiffness of the metal low-frequency beam to increase with the increase of displacement;

[0028] In the separation stage, the metal low-frequency beam moves downward under external excitation and separates from the piezoelectric high-frequency beam; at the same time, the piezoelectric high-frequency beam is excited by the impact effect and oscillates at its own higher resonant frequency, thus realizing the transition from low-frequency vibration to high-frequency oscillation.

[0029] Furthermore, when the external vibration excitation acceleration is small, the block does not collide with the first permanent magnet under the piezoelectric high-frequency beam, and the second permanent magnet on the metal low-frequency beam moves the first permanent magnet under the piezoelectric high-frequency beam through magnetic attraction, so that the piezoelectric layer on the piezoelectric high-frequency beam is deformed, thereby collecting low-frequency vibration energy, including:

[0030] When the metal low-frequency beam is excited by external low-frequency vibration, the vibration characteristics of the metal low-frequency beam change due to the attraction between the first permanent magnet and the second permanent magnet, and the vibration characteristics include equivalent stiffness and resonance frequency range;

[0031] The metal low-frequency beam moves downward under external excitation and separates from the high-frequency beam; at the same time, the piezoelectric high-frequency beam is moved by the magnetic force and also oscillates at its own higher resonant frequency, realizing the transition from low-frequency vibration to high-frequency oscillation.

[0032] The advantages of the present invention are:

[0033] 1) The present invention integrates the piezoelectric effect and electromagnetic induction into the same vibration energy collection device, effectively improving the energy collection efficiency and power generation efficiency.

[0034] 2) The present invention combines the two mechanisms of collision frequency up-conversion and magnetic frequency up-conversion, and uses magnetic attraction to increase the mechanical impact of the block on the piezoelectric high-frequency beam, thereby effectively improving the energy collection efficiency of the vibration energy collector.

[0035] 3) The present invention combines the two mechanisms of collision frequency up-conversion and magnetic frequency up-conversion. When the external excitation is weak, the magnetic attraction is used to realize the magnetic pulling of the piezoelectric high-frequency beam, which can effectively collect weak low-frequency vibration energy.

[0036] 4) The present invention adds high magnetic permeability materials inside the coil, which can improve the output of the electromagnetic module.

[0037] 5) The energy harvesting device designed by the present invention can effectively harvest the weak excitation, low-frequency, wide-range and random vibration energy in the natural environment to power the micro wireless sensor network nodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered as a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0039] Figure 1 A schematic structural diagram of the energy harvesting device according to an embodiment of the present invention is shown.

[0040] Figure 2 A cross-sectional view of the coil according to an embodiment of the present invention is shown.

[0041] Figure 3 A schematic diagram of the high-intensity excitation condition according to an embodiment of the present invention is shown.

[0042] Figure 4 A schematic diagram of the working principle of the energy harvesting device according to an embodiment of the present invention is shown.

[0043] Figure 5 A schematic diagram of the low-intensity excitation condition according to an embodiment of the present invention is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0045] The energy harvesting device designed by the present invention is a composite energy harvesting device of piezoelectric-electromagnetic power generation mode. The core components of the piezoelectric power generation module include a piezoelectric high-frequency beam, a metal low-frequency beam, a stopper and a permanent magnet. The core components of the electromagnetic power generation module include a coil, a magnetic conductive material and a permanent magnet.

[0046] The magnets at the ends of the piezoelectric high-frequency beam and the metal low-frequency beam in this device have opposite magnetic poles and attract each other. The magnetic attraction is used to enhance the mechanical impact of the stopper at the end of the metal low-frequency beam on the piezoelectric high-frequency beam, thereby improving the energy harvesting efficiency of the vibration energy harvester.

[0047] This device combines the mechanisms of impact frequency-upconversion and magnetic frequency-upconversion, and can effectively collect low-frequency vibration energy at various excitation levels through mechanical impact or magnetic actuation.

[0048] Figure 1 , 2 FIG. is a schematic structural diagram of the energy harvesting device in the present invention, which mainly consists of two parts: a piezoelectric power generation module and an electromagnetic power generation module. Among them, the permanent magnet 6 (which can be, but is not limited to, an N35 permanent magnet) includes two parts, namely a first permanent magnet and a second permanent magnet. The piezoelectric high-frequency beam 1, the metal low-frequency beam 2, the stopper 3, and the first permanent magnet form the piezoelectric power generation module; the second permanent magnet, the coil 5, the magnetic conductive material 4, and the coil shaft 7 form the electromagnetic power generation module. Next, each module will be introduced in detail.

[0049] Piezoelectric power generation module: The piezoelectric high-frequency beam 1 is made of a flexible metal material with good elasticity and no magnetism, such as beryllium bronze, phosphor bronze, stainless steel, etc. The piezoelectric layer, such as piezoelectric ceramics, PVDF piezoelectric films, etc., is attached to the metal substrate as the power generation layer. One end of the piezoelectric high-frequency beam 1 is fixed, and the other end can move freely. A square first permanent magnet is fixed below the free end of the piezoelectric high-frequency beam 1, and the polarization direction of the first permanent magnet is perpendicular to the surface of the piezoelectric high-frequency beam 1. The metal low-frequency beam 2 is made of a metal material with good elasticity and no magnetism, such as stainless steel. One end of the metal low-frequency beam 2 is fixed, and the other end can move freely. A square second permanent magnet is fixed above the free end of the metal low-frequency beam 2, and the polarization direction of the second permanent magnet is perpendicular to the surface of the metal low-frequency beam 2. The stopper 3 is made of a photosensitive resin material and is glued above the second permanent magnet. The magnetic poles of the upper and lower permanent magnets are opposite and attract each other. When the external vibration excitation frequency is close to the natural frequency of the metal low-frequency beam 2 with the stopper 3 and the second permanent magnet at the end, the metal low-frequency beam 2 will resonate, driving the stopper 3 and the second permanent magnet to perform large-amplitude oscillating motions. When the external vibration excitation acceleration is large, the stopper 3 collides with the first permanent magnet below the piezoelectric high-frequency beam 1, causing a large deformation of the piezoelectric layer on the piezoelectric high-frequency beam 1. Due to the piezoelectric effect, charges with opposite polarities accumulate on the upper and lower surfaces of the piezoelectric layer, and the piezoelectric module generates electricity. When the external vibration excitation acceleration is small, the stopper 3 does not collide with the first permanent magnet below the piezoelectric high-frequency beam 1, and the second permanent magnet on the metal low-frequency beam 2 actuates the first permanent magnet below the piezoelectric high-frequency beam through magnetic attraction, causing the piezoelectric layer on the piezoelectric high-frequency beam 1 to deform, thereby collecting energy.

[0050] Electromagnetic power generation module: The annular coil 5 is wound with enameled copper wire and fixed on the coil shaft 7 inside the coil hole; the magnetic conductive material 4 is composed of thin sheets of high magnetic conductive materials such as silicon steel sheets and Permalloy, and the number and size of the high magnetic conductive sheets need to select the optimal value according to actual tests. The magnetic conductive material 4 is fixed in the through hole at the center of the coil shaft 7 and is placed at a certain distance from the second permanent magnet. Under external excitation, the metal low-frequency beam 2 will drive the second permanent magnet at the end to vibrate up and down, and the magnetic flux will change in the coil 5 facing the magnet, so that the coil cuts the magnetic flux lines to generate electricity; adding the magnetic conductive material 4 at the center of the coil can concentrate the magnetic flux lines inside the coil, increase the magnetic flux change inside the coil, and increase the output of the electromagnetic power generation module.

[0051] Working principle:

[0052] The vibration energy harvesting device designed in the present invention combines piezoelectric and electromagnetic power generation methods to collect vibration energy in the environment and convert it into electrical energy to power electronic devices. A method of using magnetic attraction to increase the mechanical impact of the block on the piezoelectric high-frequency beam is proposed, which effectively improves the energy collection efficiency of the vibration energy harvester.

[0053] Power generation principle: Piezoelectric power generation is mainly achieved by a piezoelectric high-frequency beam with a magnet at the end. When the metal low-frequency beam is excited by external low-frequency vibration, the metal low-frequency beam drives the end magnet and the block to vibrate up and down. Figure 4 As shown in the working process (I), (II), and (III) in the figure, when the external vibration excitation acceleration is large, the block collides with the permanent magnet under the piezoelectric high-frequency beam. The magnetic attraction increases the mechanical impact of the block on the piezoelectric high-frequency beam, causing the piezoelectric layer on the piezoelectric high-frequency beam to deform significantly. The upper and lower surfaces of the piezoelectric layer accumulate charges of opposite polarity, and the piezoelectric module generates electricity. Figure 3 As shown in Figure 2, under the same conditions, the magnetic force enhancement mechanism has a lower operating frequency and a higher peak voltage compared to the traditional collision frequency-upgrading mechanism. Figure 4 As shown in the working process (I), (II'), and (III) in , when the external vibration excitation acceleration is small, the block does not collide with the permanent magnet under the piezoelectric high-frequency beam. The permanent magnet on the metal low-frequency beam moves the permanent magnet under the piezoelectric high-frequency beam through magnetic attraction, causing the piezoelectric layer on the piezoelectric high-frequency beam to deform, thereby collecting low-frequency vibration energy. Figure 5 As shown in the figure, under the same conditions, compared with the traditional collision frequency-increasing mechanism, the magnetic force enhancement mechanism can effectively collect weak low-frequency vibration energy from the outside and has a lower operating frequency. At the same time, the metal low-frequency beam will drive the end magnet to vibrate up and down, and the magnetic flux in the coil facing the magnet will change accordingly, so that the coil cuts the magnetic flux lines to generate electricity; adding magnetic conductive material at the center of the coil can concentrate the magnetic flux lines inside the coil, increase the magnetic flux change inside the coil, and increase the output of the electromagnetic power generation module.

[0054] Principle of frequency up-conversion:

[0055] 1) Collision frequency up-conversion: Figure 4 As shown in the working process (I), (II), and (III) in Figure 1, a collision cycle process can be divided into three stages, including the approach stage, the collision stage, and the separation stage. In the approach stage, the metal low-frequency beam is bent and moves upward due to external excitation. Since the gap distance is smaller than the vibration amplitude of the metal low-frequency beam, the metal low-frequency beam collides with the piezoelectric high-frequency beam in each vibration cycle. This collision causes the amplitude of the metal low-frequency beam to decrease and the working bandwidth to become wider. When the metal low-frequency beam contacts the piezoelectric high-frequency beam, the upward movement of the end of the metal low-frequency beam is constrained by the piezoelectric high-frequency beam. This constraint causes the overall stiffness of the metal low-frequency beam to increase with the increase of displacement. The higher overall stiffness increases the resonant frequency of the metal low-frequency beam, allowing the resonance to extend over a wider spectrum range. Thereafter, the metal low-frequency beam moves downward under external excitation and separates from the piezoelectric high-frequency beam. At the same time, the piezoelectric high-frequency beam is excited by the impact effect and oscillates at its own higher resonant frequency, thereby achieving a transition from low-frequency vibration to high-frequency oscillation.

[0056] 2) Magnetic frequency up-conversion: Figure 4 As shown in the working process of (I), (II'), and (III) in , the magnet at the end of the piezoelectric high-frequency beam and the magnet at the end of the metal low-frequency beam attract each other to form magnetic coupling. When the metal low-frequency beam is excited by external low-frequency vibration, the vibration characteristics of the metal low-frequency beam change due to the attraction between the two magnets. The attraction will provide additional restoring force for the metal low-frequency beam, which is equivalent to changing the equivalent stiffness of the metal low-frequency beam. With the change of equivalent stiffness, according to vibration theory, the resonant frequency of the metal low-frequency beam will also change. This change is not fixed at a single frequency point, but expands the resonant frequency range of the metal low-frequency beam, thereby achieving a widening of the working frequency band. Similar to the collision up-conversion mechanism, in the magnetic up-conversion mechanism, the metal low-frequency beam moves downward under external excitation and separates from the piezoelectric high-frequency beam. At the same time, the piezoelectric high-frequency beam is also moved at its own higher resonant frequency by the magnetic force, realizing the transition from low-frequency vibration to high-frequency oscillation.

[0057] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A magnetic force enhanced vibration energy harvesting device, characterized in that include: Piezoelectric power generation module and electromagnetic power generation module; wherein, The piezoelectric power generation module includes a piezoelectric high-frequency beam, a metal low-frequency beam, a stopper and a first permanent magnet; The electromagnetic power generation module includes a second permanent magnet, a coil, a magnetic conductive material and a coil shaft. The coil shaft is arranged inside the coil, the magnetic conductive material is located in the center hole of the coil shaft, and the coil is arranged around the magnetic conductive material.

2. A magnetically enhanced vibration energy harvesting device according to claim 1, characterized in that: The piezoelectric high-frequency beam uses a flexible metal material with elasticity and no magnetism as a substrate, and is prepared by attaching a piezoelectric material as a power generation layer to a metal substrate. One end of the piezoelectric high-frequency beam is fixed, and the other end can move freely. A first permanent magnet is fixed to the lower surface of the free end of the piezoelectric high-frequency beam, and the polarization direction of the first permanent magnet is perpendicular to the surface of the piezoelectric high-frequency beam.

3. The magnetic force enhanced vibration energy harvesting device according to claim 1, characterized in that: The metal low-frequency beam is made of an elastic and non-magnetic metal material; one end of the metal low-frequency beam is fixed, and the other end can move freely; A second permanent magnet is fixed on the upper surface of the free end of the metal low-frequency beam, and the polarization direction of the second permanent magnet is perpendicular to the surface of the metal low-frequency beam.

4. A magnetically enhanced vibration energy harvesting device according to claim 1 or 3, characterized in that: The stopper is made of a photosensitive resin material and is adhered to the second permanent magnet; the relative magnetic poles of the first permanent magnet and the second permanent magnet have opposite magnetic properties.

5. A magnetically enhanced vibration energy harvesting device according to claim 1 or 3, characterized in that: The coil is wound by enameled copper wire and fixed on a coil shaft inside the coil.

6. A magnetically enhanced vibration energy harvesting device according to claim 1 or 3, characterized in that: The magnetic conductive material is composed of stacked sheets of high magnetic conductive material. The magnetic conductive material is fixed in a through hole at the center of the coil axis and is placed at a certain distance from the second permanent magnet.

7. A magnetically enhanced vibration energy collection method using the device according to any one of claims 1 to 6, characterized in that: When the metal low-frequency beam is excited by external low-frequency vibration, the metal low-frequency beam drives the second permanent magnet and the stopper at the end to vibrate up and down; When the external vibration excitation acceleration is large, the block collides with the first permanent magnet under the piezoelectric high-frequency beam, causing the piezoelectric layer on the piezoelectric high-frequency beam to deform significantly, and charges with opposite polarities accumulate on the upper and lower surfaces of the piezoelectric layer, and the piezoelectric power generation module generates electricity; When the external vibration excitation acceleration is small, the block does not collide with the first permanent magnet under the piezoelectric high-frequency beam. The second permanent magnet on the metal low-frequency beam moves the first permanent magnet under the piezoelectric high-frequency beam through magnetic attraction, causing the piezoelectric layer on the piezoelectric high-frequency beam to deform, thereby collecting low-frequency vibration energy.

8. The magnetic force enhanced vibration energy collection method according to claim 7, characterized in that: When the external vibration excitation acceleration is large, the block collides with the first permanent magnet under the piezoelectric high-frequency beam, causing the piezoelectric layer on the piezoelectric high-frequency beam to deform significantly, and charges with opposite polarities accumulate on the upper and lower surfaces of the piezoelectric layer. The piezoelectric power generation module generates electricity, including: A collision cycle process is divided into three stages, including approach stage, collision stage and separation stage; In the approaching stage, the metal low-frequency beam bends and moves upward due to external excitation. Since the gap distance is smaller than the vibration amplitude of the metal low-frequency beam, the metal low-frequency beam collides with the piezoelectric high-frequency beam in each vibration cycle. In the collision stage, when the metal low-frequency beam contacts the piezoelectric high-frequency beam, the upward movement of the end of the metal low-frequency beam is constrained by the piezoelectric high-frequency beam, and the constraint causes the overall stiffness of the metal low-frequency beam to increase with the increase of displacement; In the separation stage, the metal low-frequency beam moves downward under external excitation and separates from the piezoelectric high-frequency beam; at the same time, the piezoelectric high-frequency beam is excited by the impact effect and oscillates at its own higher resonant frequency, thus realizing the transition from low-frequency vibration to high-frequency oscillation.

9. The magnetic force enhanced vibration energy collection method according to claim 7, characterized in that: When the external vibration excitation acceleration is small, the block does not collide with the first permanent magnet under the piezoelectric high-frequency beam, and the second permanent magnet on the metal low-frequency beam moves the first permanent magnet under the piezoelectric high-frequency beam through magnetic attraction, so that the piezoelectric layer on the piezoelectric high-frequency beam is deformed, thereby collecting low-frequency vibration energy, including: When the metal low-frequency beam is excited by external low-frequency vibration, the vibration characteristics of the metal low-frequency beam change due to the attraction between the first permanent magnet and the second permanent magnet, and the vibration characteristics include equivalent stiffness and resonance frequency range; The metal low-frequency beam moves downward under external excitation and separates from the piezoelectric high-frequency beam; at the same time, the piezoelectric high-frequency beam is moved by the magnetic force and also oscillates at its own higher resonant frequency, achieving the transition from low-frequency vibration to high-frequency oscillation.

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