Magnetic force enhanced vibration energy collecting device

Abstract

The utility model provides a magnetic force enhanced vibration energy collection device, which 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. In order to solve 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 collection module, and an electromagnetic power generation module is introduced at the same time. 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] This utility model relates to the field of energy harvesting technology, specifically to a magnetically enhanced vibration energy harvesting device. Background Technology

[0002] With the rapid development of wireless sensor networks and wearable electronic devices, the power consumption of microelectronics has been reduced to the microwatt level. Traditional battery power supply methods suffer from problems such as large size, environmental pollution, and the need for regular replacement. Providing a long-term, stable power source for microelectronic devices is a key technical challenge that needs to be overcome. The environment contains a large amount of vibration energy, such as vibrations generated by mechanical operation, vehicle movement, human movement, and airflow. This vibration energy is a sustainable and clean energy source. Effectively collecting and converting this energy into electrical energy could provide an ideal self-powered solution for low-power devices, reducing reliance on traditional batteries. Currently, piezoelectric vibration energy harvesters are a common type of vibration energy harvesting device. They utilize the positive piezoelectric effect of piezoelectric materials to convert mechanical vibration energy into electrical energy, thereby providing a long-term, stable power supply for micro-low-power wireless sensor network nodes.

[0003] However, traditional piezoelectric vibration energy harvesters have a key limitation: their resonant frequency is relatively fixed. Vibration frequencies in real-world environments are complex and diverse; for example, the vibration frequency of machinery can vary from a few hertz to hundreds of hertz. When the frequency of the vibration source does not match the resonant frequency of the harvester, the energy harvesting efficiency drops sharply, significantly limiting its application in practical environments. Therefore, effective measures are needed to broaden the operating bandwidth of energy harvesters and enhance their output performance, thereby accelerating the development of wireless sensor networks.

[0004] Currently, there are two main working mechanisms for widening the bandwidth and enhancing the output performance of piezoelectric vibration energy harvesters: collision-based frequency upscaling and magnetic-based frequency upscaling. The collision-based frequency upscaling mechanism of a piezoelectric vibration energy harvester mainly consists of three stages: approach, collision, and separation. In the approach stage, the low-frequency beam bends and moves upward under external excitation. Because the gap distance is smaller than the vibration amplitude of the low-frequency beam, the low-frequency beam excites the high-frequency beam in each vibration cycle. When the low-frequency beam contacts the high-frequency beam, the higher stiffness of the high-frequency beam results in a much smaller displacement amplitude at the end of the high-frequency beam. Therefore, the upward movement of the low-frequency beam end is constrained by the high-frequency beam, causing the overall stiffness of the low-frequency beam to increase with displacement. Consequently, the resonant frequency of the low-frequency beam gradually increases during the collision process, exhibiting the mechanical characteristics of a nonlinear spring. This nonlinear characteristic effectively widens the operating bandwidth of the harvester. Afterward, the low-frequency beam moves downward under external excitation and separates from the high-frequency beam. Meanwhile, the high-frequency beam, excited by the impact effect, 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 frequency upscaling mechanism of piezoelectric vibration energy harvesters primarily utilizes magnetic interaction to broaden the operating bandwidth and enhance output performance. It typically involves placing magnets at the ends of both the high-frequency and low-frequency beams, generating nonlinear forces through magnetic fields. When vibration occurs, the magnetic force alters the system's vibration characteristics, effectively changing its equivalent stiffness. According to vibration theory, the system's resonant frequency also changes, allowing it to respond to vibrations of different frequencies and thus broadening the operating bandwidth. Similar to the impact-based frequency upscaling mechanism, in the magnetic frequency upscaling mechanism, the low-frequency beam moves downwards under external excitation, separating from the high-frequency beam. Simultaneously, the high-frequency beam, propelled by the magnetic force, oscillates at its higher resonant frequency, achieving a transition from low-frequency to high-frequency vibration. However, the non-contact magnetic excitation effect on the high-frequency beam in the magnetic frequency upscaling mechanism is less than the contact mechanical impact produced by the impact-based mechanism. Furthermore, the operating bandwidth of the magnetic frequency upscaling mechanism is narrower than that of the impact-based mechanism. Therefore, the energy harvesting efficiency of the magnetic frequency upscaling mechanism is relatively low.

[0006] The main problems with existing vibration energy harvesting are low energy conversion efficiency, low power generation, narrow operating bandwidth, and poor environmental adaptability, all of which require further improvement. Traditional linear energy harvesters have only a single natural frequency, resulting in a very narrow amplitude-frequency response curve. In real-world environments, vibration frequencies are complex and variable. Once the external excitation frequency does not match the natural frequency, the output power drops significantly, preventing most of the vibration energy from being effectively harvested. Piezoelectric materials have high output impedance and dielectric loss. In low-frequency vibration environments, piezoelectric energy harvesters are inefficient at converting mechanical energy into electrical energy, making it difficult to meet the power requirements of low-power devices such as wireless sensors. Although research has identified various mechanisms that can broaden the operating bandwidth of vibration energy harvesters and enhance output performance, they all have shortcomings. For example, collision-based frequency upscaling mechanisms have certain requirements on the excitation intensity of external vibrations, while magnetic frequency upscaling mechanisms have a narrow operating bandwidth and low energy harvesting efficiency. Integrating multiple mechanisms into a single device to leverage their respective strengths and compensate for their weaknesses, thereby further improving vibration energy harvesting and conversion efficiency, remains a key technical challenge. Utility Model Content

[0007] The objective of this utility model is achieved through the following technical solution.

[0008] This invention addresses the issues of narrow operating bandwidth and low energy output in vibration energy harvesters by combining collision-based frequency upscaling and magnetic-based frequency upscaling into a single piezoelectric energy harvesting module, while also incorporating an electromagnetic power generation module. This improves energy conversion efficiency and overall power generation, enabling energy harvesting over a wide frequency range. It effectively collects low-frequency vibration energy with a wide variation range from the environment and converts it into electrical energy to power wireless sensing nodes.

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

[0010] Piezoelectric power generation modules and electromagnetic power generation modules; among them,

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

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

[0013] Furthermore, the piezoelectric high-frequency beam uses a flexible metal material that is elastic and non-magnetic as a substrate, and is prepared by attaching the piezoelectric material as a power generation layer onto the metal substrate. One end of the piezoelectric high-frequency beam is fixed, while 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 low-frequency metal beam is made of an elastic and non-magnetic metal material; one end of the low-frequency metal beam is fixed, while the other end can move freely.

[0016] A second permanent magnet is fixed to 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 stop is made of photosensitive resin material and is attached above the second permanent magnet; the magnetic poles of the first permanent magnet and the second permanent magnet have opposite magnetic properties.

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

[0019] Furthermore, the magnetic conductive material is composed of layers of highly magnetically permeable material, and the magnetic conductive material is fixed in a through hole at the center of the coil shaft and placed at a certain distance from the second permanent magnet.

[0020] The advantages of this utility model are:

[0021] 1) This utility model integrates piezoelectric effect and electromagnetic induction power generation methods into the same vibration energy harvesting device, which effectively improves energy harvesting efficiency and power generation efficiency.

[0022] 2) This utility model combines two mechanisms: collision frequency upscaling and magnetic frequency upscaling. It utilizes the magnetic attraction force to increase the mechanical impact of the stop block on the piezoelectric high-frequency beam, effectively improving the energy collection efficiency of the vibration energy harvester.

[0023] 3) This utility model combines two mechanisms: collision frequency upscaling and magnetic frequency upscaling. When the external excitation is weak, the magnetic attraction force is used to achieve magnetic piezoelectric high-frequency beam paddle movement, which can effectively collect weak low-frequency vibration energy.

[0024] 4) This invention incorporates a high-permeability material inside the coil, which can improve the output of the electromagnetic module.

[0025] 5) The energy harvesting device designed in this utility model can effectively collect weak excitation, low frequency, wide variation range and random vibration energy in the natural environment to power the nodes of the micro wireless sensor network. Attached Figure Description

[0026] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0027] Figure 1 A schematic diagram of the structure of an energy harvesting device according to an embodiment of the present invention is shown.

[0028] Figure 2 A cross-sectional view of a coil according to an embodiment of the present invention is shown.

[0029] Figure 3 A schematic diagram of a high-intensity excitation condition according to an embodiment of the present invention is shown.

[0030] Figure 4 A schematic diagram illustrating the working principle of an energy harvesting device according to an embodiment of the present invention is shown.

[0031] Figure 5 A schematic diagram of a low-intensity excitation condition according to an embodiment of the present invention is shown. Detailed Implementation

[0032] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0033] The energy harvesting device designed in this utility model is a piezoelectric-electromagnetic power generation composite energy harvesting device. The core components of the piezoelectric power generation module include a piezoelectric high-frequency beam, a metal low-frequency beam, a stop block, and a permanent magnet. The core components of the electromagnetic power generation module include a coil, a magnetic material, and a permanent magnet.

[0034] In this device, the magnet at the end of the piezoelectric high-frequency beam and the magnet at the end of the metal low-frequency beam have opposite magnetic poles and attract each other. The magnetic attraction enhances the mechanical impact of the stop block 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.

[0035] This device combines collision-based frequency upscaling and magnetic-based frequency upscaling mechanisms, and can effectively collect low-frequency vibration energy under various excitation levels through mechanical impact or magnetic manipulation.

[0036] Figure 1 , 2This is a schematic diagram of the energy harvesting device in this utility model, mainly composed of two parts: a piezoelectric power generation module and an electromagnetic power generation module. The permanent magnet 6 (which can be, but is not limited to, N35 permanent magnets) comprises two parts: a first permanent magnet and a second permanent magnet. The piezoelectric high-frequency beam 1, the metal low-frequency beam 2, the stop block 3, and the first permanent magnet constitute the piezoelectric power generation module; the second permanent magnet, the coil 5, the magnetically conductive material 4, and the coil shaft 7 constitute the electromagnetic power generation module. The following sections will describe each module in detail.

[0037] Piezoelectric power generation module: The piezoelectric high-frequency beam 1 uses flexible metal materials with good elasticity and non-magnetic properties, such as beryllium bronze, phosphor bronze, and stainless steel, as the substrate. It is fabricated by attaching piezoelectric materials, such as piezoelectric ceramics or PVDF piezoelectric films, as the power generation layer onto the metal substrate. One end of the piezoelectric high-frequency beam 1 is fixed, while the other end is free to move. A square first permanent magnet is fixed below the free end of the piezoelectric high-frequency beam 1, with its polarization direction 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 non-magnetic properties, such as stainless steel. One end of the metal low-frequency beam 2 is fixed, while the other end is free to move. A square second permanent magnet is fixed above the free end of the metal low-frequency beam 2, with its polarization direction perpendicular to the surface of the metal low-frequency beam 2. The stop block 3 is made of photosensitive resin material and is glued above the second permanent magnet. The two permanent magnets have opposite magnetic poles and attract each other. When the external vibration excitation frequency is close to the natural frequency of the low-frequency metal beam 2, which is equipped with a stop block 3 and a second permanent magnet at its end, the low-frequency metal beam 2 will resonate, causing the stop block 3 and the second permanent magnet to oscillate significantly. When the external vibration excitation acceleration is large, the stop block 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, oppositely polarized charges accumulate on the upper and lower surfaces of the piezoelectric layer, generating electricity from the piezoelectric module. When the external vibration excitation acceleration is small, the stop block 3 does not collide with the first permanent magnet below the piezoelectric high-frequency beam 1. The second permanent magnet on the low-frequency metal beam 2 uses magnetic attraction to move the first permanent magnet below the piezoelectric high-frequency beam, causing the piezoelectric layer on the piezoelectric high-frequency beam 1 to deform, thereby collecting energy.

[0038] Electromagnetic power generation module: The annular coil 5 is made of 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 permeability materials such as silicon steel sheets and permalloy, and the number and size of the high magnetic permeability sheets need to be selected according to the actual test to obtain the optimal value. 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 coil 5 facing the magnet will generate a corresponding change in magnetic flux, so that the coil cuts the magnetic field lines to generate electricity; adding magnetic conductive material 4 at the center of the coil can concentrate the magnetic field lines inside the coil, increase the change in magnetic flux inside the coil, and increase the output of the electromagnetic power generation module.

[0039] Working principle:

[0040] This invention designs a vibration energy harvesting device that combines piezoelectric and electromagnetic power generation methods. It is used to collect vibration energy from the environment and convert it into electrical energy to power electronic devices. Furthermore, it proposes a method to increase the mechanical impact of the piezoelectric high-frequency beam by using magnetic attraction to increase the mechanical impact of the block, which effectively improves the energy harvesting efficiency of the vibration energy harvester.

[0041] Power generation principle: Piezoelectric power generation mainly relies on a piezoelectric high-frequency beam with a magnet at its end. When the metal low-frequency beam is excited by external low-frequency vibration, the metal low-frequency beam drives the end magnet and stop block to vibrate up and down. Figure 4 As shown in the workflow (I), (II), and (III), when the external vibration excitation acceleration is large, the stop block collides with the permanent magnet below the piezoelectric high-frequency beam. Due to the increased magnetic attraction, the mechanical impact of the stop block on the piezoelectric high-frequency beam is increased, causing a large deformation of the piezoelectric layer on the piezoelectric high-frequency beam. The upper and lower surfaces of the piezoelectric layer accumulate charges of opposite polarities, and the piezoelectric module generates electricity. Figure 3 As shown, under the same conditions, compared with the traditional collision-based frequency upsampling mechanism, the magnetic enhancement mechanism has a lower operating frequency and a higher peak voltage. Figure 4 As shown in the workflow (I), (II'), and (III), when the external vibration excitation acceleration is small, the stop block does not collide with the permanent magnet below the piezoelectric high-frequency beam. The permanent magnet on the metal low-frequency beam moves the permanent magnet below 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, under the same conditions, compared with the traditional collision-based frequency upscaling mechanism, the magnetic enhancement mechanism can effectively collect weak low-frequency vibration energy from the outside and has a lower operating frequency. Simultaneously, the low-frequency metal beam drives the end magnet to vibrate up and down, resulting in a corresponding change in magnetic flux within the coil opposite the magnet. This causes the coil to cut magnetic field lines and generate electricity. Adding a magnetically conductive material at the center of the coil concentrates the magnetic field lines inside the coil, increasing the change in magnetic flux within the coil and thus increasing the output of the electromagnetic power generation module.

[0042] Upsampling and frequency expansion principle:

[0043] 1) Collision-induced frequency upsampling and frequency extension: such as Figure 4 As shown in the workflows (I), (II), and (III), a collision cycle can be divided into three stages: the approach stage, the collision stage, and the separation stage. In the approach stage, the low-frequency metal beam bends and moves upward under external excitation. Because the gap distance is smaller than the vibration amplitude of the low-frequency metal beam, it collides with the piezoelectric high-frequency beam in each vibration cycle. This collision reduces the amplitude of the low-frequency metal beam and widens its operating bandwidth. When the low-frequency metal beam contacts the piezoelectric high-frequency beam, the upward movement of the end of the low-frequency metal beam is constrained by the piezoelectric high-frequency beam. This constraint causes the overall stiffness of the low-frequency metal beam to increase with the increase of displacement. The higher overall stiffness increases the resonant frequency of the low-frequency metal beam, allowing the resonance to extend over a wider frequency range. Subsequently, the low-frequency metal beam moves downward under external excitation and separates from the piezoelectric high-frequency beam. Simultaneously, the piezoelectric high-frequency beam is excited by the impact effect and oscillates at its own higher resonant frequency, thus achieving the transition from low-frequency vibration to high-frequency oscillation.

[0044] 2) Magnetic frequency upscaling: such as Figure 4 As shown in steps (I), (II'), and (III) of the process, the magnets at the ends of the piezoelectric high-frequency beam and the metal low-frequency beam attract each other, forming magnetic coupling. When the metal low-frequency beam is excited by external low-frequency vibration, its vibration characteristics change due to the attraction between the two magnets. The attraction provides additional restoring force to the metal low-frequency beam, which is equivalent to changing its equivalent stiffness. With the change in equivalent stiffness, the resonant frequency of the metal low-frequency beam also changes according to vibration theory. This change is not fixed at a single frequency point, but rather expands the resonant frequency range of the metal low-frequency beam, thereby widening the operating frequency band. Similar to the collision-based frequency upscaling mechanism, in the magnetic frequency upscaling 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, propelled by the magnetic force, can also oscillate at its own higher resonant frequency, achieving a transition from low-frequency vibration to high-frequency oscillation.

[0045] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A magnetically enhanced vibration energy harvesting device, characterized in that, include: Piezoelectric power generation modules and electromagnetic power generation modules; among them, The piezoelectric power generation module includes a piezoelectric high-frequency beam, a metal low-frequency beam, a stop block, and a first permanent magnet. The electromagnetic power generation module includes a second permanent magnet, a coil, a magnetic material, and a coil shaft. The coil shaft is disposed inside the coil, the magnetic material is located in the central hole of the coil shaft, and the coil is arranged around the magnetic material.

2. The magnetically enhanced vibration energy harvesting device according to claim 1, characterized in that, The piezoelectric high-frequency beam uses a flexible metal material that is elastic and non-magnetic as a substrate. It is prepared by attaching the piezoelectric material as a power generation layer onto the metal substrate. One end of the piezoelectric high-frequency beam is fixed, while 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 magnetically enhanced vibration energy harvesting device according to claim 1, characterized in that, The low-frequency metal beam is made of an elastic and non-magnetic metal material; one end of the low-frequency metal beam is fixed, while the other end can move freely. A second permanent magnet is fixed to 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 block is made of photosensitive resin material and is attached above the second permanent magnet; the 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 made of enameled copper wire and is 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 material is composed of layers of highly permeable magnetic material. The magnetic material is fixed in a through hole at the center of the coil shaft and is placed at a certain distance from the second permanent magnet.

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