Cross bending type magnetostriction-epoxy resin composite energy collector

Abstract

The invention relates to a cross bending type magnetostriction-epoxy resin composite energy collector. The energy collector comprises a magnetostriction-epoxy resin composite structure, a pickup coil and a bias magnet, wherein the magnetostriction-epoxy resin composite structure is a cross bent structure, and each of four end parts of the structure is wound with a pickup coil; the bias magnet is fixed right above the pickup coil; and the magnetostriction layer is an iron-cobalt-vanadium alloy sheet. The invention has the advantages of simple structure, high mechanical strength, wear resistance, large output signal and the like, and is extremely suitable for the field of transient vibration energy collection.

Description

Technical Field:

[0001] The present invention relates to the field of transient vibration energy harvesting, and more particularly, to a magnetostrictive energy harvester capable of realizing transient vibration energy harvesting. Background Art:

[0002] So far, most microelectronic devices are powered by traditional chemical batteries. However, traditional batteries have problems such as short lifespan, inconvenient replacement, and environmental pollution. Therefore, collecting potential energy in the environment to replace traditional batteries for powering microelectronic devices has received extensive attention from scholars at home and abroad. Usually, a device that converts the energy collected from the environment into electrical energy is called an energy harvester. The energy harvester can continuously collect various energies in the environment without human intervention and has no pollution to the environment. The energies available for collection are widely distributed in nature and daily life, and these energies usually exist in the forms of vibration energy, solar energy, temperature difference energy, electromagnetic energy, and airflow energy, etc. Among various environmental energies, vibration energy is a potential power source for distributed microelectronic devices due to its rich availability, high energy conversion efficiency, and environmental friendliness. Vibration energy harvesting technologies are mainly divided into electrostatic, piezoelectric, and magnetostrictive types. The electrostatic type has a single structure and limited design. For example, most of the multi-layer integrations of contact electrification electrostatic acquisition devices are simple vertical stacks, and often require high-frequency reciprocating action to drive to have a high output, which limits its application scenarios. Piezoelectric materials are brittle and are easily damaged during long-term operation, and charge leakage is likely to occur. Among them, magnetostrictive materials, with their unique force-magnetic coupling effect, can convert the applied stress / strain into magnetic changes, and then collect electrical energy in a coil, ultimately achieving fast and efficient energy harvesting. Compared with electromagnetic, piezoelectric, and other energy harvesting technologies, it has advantages in terms of applicable frequency band, conversion efficiency, energy density, etc.

[0003] Currently, the magnetostrictive vibration energy harvesting technology still faces many challenges such as low material pressure resistance and complex structural design. For example: Document No. 10.3390 / ma12132055, Energy Harvesting of an Integrated Shoe with Magnetostrictive Fibers. This paper uses magnetostrictive fibers as the core component and designs a composite shoe integrated with magnetostrictive fibers, aiming to amplify weak transient vibrations and achieve transient vibration energy harvesting. However, the magnetostrictive fiber composite shoe has poor mechanical properties, and the output signal is likely to decrease during long-term use. At the same time, the composite structure design is relatively complex, and it can withstand less impact force, which is not conducive to large-scale production and popularization. Summary of the Invention:

[0004] The object of the present invention is to address the deficiencies in the current technology. The present invention proposes a cross-bending magnetostrictive-epoxy composite energy harvester. This harvester adopts a novel structure of cross-bending + magnetostrictive-epoxy composite. Compared with the magnetostrictive fiber composite shoe structure, the cross-bending structure has a certain curvature and more stress points. After being subjected to an impact force, the degree of deformation is greater and the stability is better. It can make full use of the magnetic domains of the magnetostrictive layer, enhancing the energy harvesting efficiency of the harvester. At the same time, it also adopts the magnetostrictive-epoxy composite form, further improving the mechanical strength of the harvester, withstanding a greater impact force and having good force stability. This innovative design fully improves the harvesting efficiency of the energy harvester. The present invention has the advantages of simple structure, high mechanical strength, wear resistance, large output signal, etc., and is extremely suitable for the field of transient vibration energy harvesting.

[0005] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0006] A cross-bending magnetostrictive-epoxy composite energy harvester, which includes a magnetostrictive-epoxy composite structure, a pickup coil, and a bias magnet;

[0007] Among them, the magnetostrictive-epoxy composite structure is a cross-bending structure, and each of the four ends of this structure is wound with a pickup coil; the bias magnet is fixed directly above the pickup coil;

[0008] The magnetostrictive-epoxy composite structure includes a magnetostrictive layer and a fixing layer; among them, the magnetostrictive layer is embedded inside the fixing layer;

[0009] The cross-bending structure includes two vertically intersecting arc-shaped strips, and the lengths and widths of the four protruding ends are equal;

[0010] The magnetostrictive layer is a FeCoV alloy sheet;

[0011] The FeCoV alloy is Fe49-Co49-V2;

[0012] The material of the pickup coil is insulated copper magnet wire, and the number of turns is 500 - 700 turns;

[0013] The material of the bias magnet is N35 neodymium iron boron permanent magnet,

[0014] The sizes of the two arc-shaped strips are the same, with a length of 15 - 18 cm, a width of 4 - 6 cm, and the radius of curvature of the arc is 15 - 20 cm; the thickness is 3 - 5 mm;

[0015] The shape of the magnetostrictive layer is the same cross-bending structure, with a length of 11 to 13 cm, a width of 2.5 to 3.5 cm, and a thickness range of 0.3 to 0.7 mm; the radius of curvature of the arc is 18 cm; the centers of the magnetostrictive layer and the fixed layer are the same;

[0016] The length occupied by each pick-up coil winding in the magnetostrictive-epoxy composite structure is 18 to 22% of the length of the magnetostrictive-epoxy composite structure;

[0017] The diameter range of the insulated copper enameled wire is 0.15 to 0.25 mm;

[0018] The size of the bias magnet is 5 cm × 3 cm × 0.5 cm;

[0019] The preparation method of the magnetostrictive-epoxy composite structure includes the following steps:

[0020] Mix the epoxy resin matrix and the curing agent in a mass ratio of 3:1, put them into a blender and stir evenly for 10 to 15 minutes, then let it stand for 8 to 16 minutes, and then pour it into a specific mold and cure at room temperature for 6 to 8 hours to obtain a precursor solution. After that, evenly place the Fe-Co-V alloy sheet into the incompletely cured precursor solution, and then pour the precursor solution of the same composition into the mold to cover the surface of the Fe-Co-V alloy sheet. Let it stand for 2 to 4 hours, take out the incompletely cured composite structure, apply an external force to the four sides of the composite structure to deform it into an arc shape, and then put it into a heating box with the temperature set at 35 to 45 °C and continue to cure for 10 to 15 hours. After complete curing, take it out and cool it at room temperature for 30 to 90 minutes to obtain the magnetostrictive-epoxy composite structure;

[0021] The epoxy resin matrix is bisphenol A; the curing agent is polyetheramine or modified amine.

[0022] The substantial features of the present invention are:

[0023] In the current technology, magnetostrictive composite energy harvesters generally adopt the form of magnetostrictive fiber integrated composite, but the mechanical properties of the magnetostrictive fiber integrated composite are poor, and the output signal is likely to decrease after long-term use. At the same time, the composite structure design is relatively complex, the pressure resistance is poor, and there are many additional losses. These factors all lead to a low energy harvesting efficiency of the device. For the field of transient vibration energy harvesting, a low energy harvesting efficiency will lead to a decrease in the output signal, so it is not suitable for the field of transient vibration energy harvesting.

[0024] The present invention adopts an iron-cobalt-vanadium alloy with better mechanical properties as a core component, and designs a new structure of cross-bending type + magnetostrictive-epoxy resin composite. Compared with the magnetostrictive fiber composite shoe structure, the cross-bending type structure has a certain curvature and more points of force. After being subjected to impact force, the deformation degree is greater and the stability is better. The magnetic domain of the magnetostrictive layer can be fully utilized, and the energy collection efficiency of the collector is enhanced. At the same time, the magnetostrictive-epoxy resin composite form is also adopted to further improve the mechanical strength of the collector, withstand greater impact force, have good force stability, and is extremely suitable for the field of transient vibration energy collection.

[0025] The main principle is: under the action of a large transient impact force, the cross-bending type has a certain curvature and more points of force, which will cause the composite structure to undergo a more stable and drastic deformation, and the internal magnetostrictive layer will also bend and deform, causing the magnetization state inside the magnetostrictive layer to change, so that the magnetic domain of the magnetostrictive layer is fully utilized, and ultimately leads to a change in magnetic flux, thereby achieving a high efficiency improvement in energy collection efficiency. At the same time, the magnetostrictive-epoxy composite design will greatly enhance the mechanical properties and force recovery of the collector. According to Faraday's law of electromagnetic induction, the pickup coil generates an induced voltage.

[0026] The beneficial effects of the present invention are:

[0027] 1. Compared with other magnetostrictive composite energy collectors, the present invention designs a curved structure with a certain curvature. Under the action of a large transient impact force, the composite structure will undergo a more stable and drastic deformation, thereby further exciting the magnetic domains of the magnetostrictive layer and improving the energy collection efficiency.

[0028] 2. At the same time, the present invention also adopts a magnetostrictive-epoxy resin composite design, which greatly enhances the mechanical properties of the collector. The invention still has good output performance under the action of multiple 1000N impact forces. Therefore, the magnetostrictive composite energy collector has the characteristics of force recovery and a wide range of applications, and can be applied to transient energy collection fields such as human body movement.

[0029] 3. The composite structure of the present invention adopts a cross shape, which is a four-sided beam type. Compared with a single-sided beam or a cantilever beam, the four-sided beam structure will make the pickup coil have a higher utilization rate for the magnetic density change length. At the same time, the structure has more fulcrums and is more likely to withstand greater impact forces. Description of the drawings:

[0030] Figure 1 This is a schematic diagram of the structure of a cross-bending magnetostrictive-epoxy resin composite energy harvester.

[0031] Figure 2 for Figure 1 Top view

[0032] Figure 3 Cross-sectional view of magnetostrictive-epoxy composite structure

[0033] Figure 4 Schematic diagram of the mold

[0034] Figure 5 Maximum output voltage diagram of the energy harvester under different impact forces

[0035] Figure 6 Mechanical stability diagram of the energy harvester under impact force;

[0036] In the figure: 1 - magnetostrictive-epoxy composite structure; 2 - pick-up coil; 3 - bias magnet; 4 - magnetostrictive layer; 5 - fixing layer; 6 - mold; Specific implementation manner:

[0037] The cross-bending magnetostrictive-epoxy composite energy harvester realizes vibration energy harvesting by utilizing the inverse magnetostrictive effect and the electromagnetic induction law. When a transient excitation is applied to the middle of the composite structure, the bending deformation generated during the vibration of the magnetostrictive layer in the fixing layer causes a change in the magnetization state inside the magnetostrictive layer, that is, a change in magnetic permeability, and finally leads to a change in magnetic flux. According to Faraday's law of electromagnetic induction, an induced voltage is generated in the pick-up coil. By integrating the inverse magnetostrictive effect and the electromagnetic induction law, this energy harvester can efficiently collect transient vibrations and convert them into output voltage.

[0038] The invention will be further described in detail below with reference to the figures. This embodiment is only a specific description of the invention and is not regarded as a limitation of the protection scope.

[0039] A cross-bending magnetostrictive-epoxy composite energy harvester proposed by the present invention, as Figure 1 shown, includes a magnetostrictive-epoxy composite structure 1, a pick-up coil 2, and a bias magnet 3;

[0040] Among them, the magnetostrictive-epoxy composite structure 1 is a cross-bending structure, and each end of the four ends of this structure is wound with a pick-up coil 2; the bias magnet 3 is fixed directly above the pick-up coil 2;

[0041] The length of the magnetostrictive-epoxy composite structure 1 occupied by each pick-up coil 2 winding is 20% of the length of the magnetostrictive-epoxy composite structure 1;

[0042] The magnetostrictive-epoxy composite structure 1 includes a magnetostrictive layer 4 and a fixing layer 5; among them, the magnetostrictive layer 4 is embedded inside the fixing layer 5, as Figure 3 shown;

[0043] The described cross-bending structure includes two arc-shaped strips that intersect perpendicularly. The lengths of the four protruding ends are equal, and the widths are also equal. The two arc-shaped strips have the same dimensions, with a length of 16 cm, a width of 5 cm, and the radius of curvature of the arc is 18 cm. The thickness ranges from 3 to 5 mm (in this embodiment, the thickness used is 4 mm).

[0044] The magnetostrictive layer 4 is a magnetostrictive alloy thin sheet made of iron-cobalt-vanadium alloy (Fe49-Co49-V2). It has the same cross-bending structure, with a length of 12 cm, a width of 3 cm, and a thickness range of 0.3 to 0.7 mm (in this embodiment, the thickness used is 0.5 mm). The radius of curvature of the arc is 18 cm. The centers of the magnetostrictive layer and the fixed layer are the same.

[0045] The preparation process of the magnetostrictive-epoxy composite structure is as follows:

[0046] Mix epoxy resin and curing agent in a mass ratio of 3:1, put them into a blender and stir evenly for 12 minutes, then let it stand for 10 minutes to obtain the precursor solution. Then pour the precursor solution into a mold with a positive cross-shaped groove (the structure of the mold is as Figure 4 shown). The pouring depth is half of the groove depth, and the groove depth is 4 mm. Cure at room temperature for 6 hours. Then place the Fe-Co-V alloy thin sheet horizontally on the incompletely cured precursor solution, and pour the precursor solution of the same composition into the mold 6 to cover the surface of the Fe-Co-V alloy thin sheet and fill the groove. Let it stand for 3 hours, take out the incompletely cured cross-shaped composite structure, apply external force to the four sides of the composite structure to make it undergo uniform deformation (until the bending radius of curvature is 18 cm), then put it into a heating box, set the temperature to 40 °C and continue to cure for 10 hours. After complete curing, take it out and cool at room temperature for 60 minutes to obtain the magnetostrictive-epoxy composite structure.

[0047] The described epoxy resin matrix is bisphenol A; the curing agent is polyetheramine or modified amine.

[0048] The material of the pickup coil is insulated copper enameled wire, with 600 turns, and the diameter range is 0.15 to 0.25 mm (in this embodiment, the thickness used is 0.2 mm).

[0049] The material of the bias magnet is N35 neodymium iron boron permanent magnet, with dimensions of 5 cm × 3 cm × 0.5 cm. The specific fixed position is directly above the pickup coil; the magnetic direction is vertically downward.

[0050] Its usage method includes the following steps:

[0051] An impact test is conducted on the energy harvester. The test platform is divided into three main parts: the power part, the excitation part, and the data acquisition and analysis part. The power part uses an air compressor as the power system to provide continuous impact power for the stamping machine. The stamping machine is the core component of the excitation system and is responsible for providing continuous impact to the composite structure. The data acquisition and analysis part includes a pressure sensor and a data acquisition card (DAQ card).

[0052] First, the air compressor is pressurized and inflated to generate sufficient air pressure. This enables the stamping machine to continuously impact the composite structure downward. The pressure sensor is placed under the composite structure to monitor the pressure change of the stamping machine in real time, while the data acquisition card is connected to the computer to process the voltage signals generated by the composite material structure collected through corresponding software.

[0053] The protocols or software involved in the present invention are all well-known technologies.

[0054] The data acquisition card (DAQ card). The DAQ card, also known as the acquisition card, is a hardware device. This device is responsible for collecting the voltage analog signals output by the energy harvester after being impacted and converting them into digital signals for transmission to the computer for subsequent processing and analysis. The acquisition card is usually connected to the computer through interfaces such as PCI, PCI Express, and USB, providing efficient data acquisition and analysis capabilities for the experiment.

[0055] By connecting the data acquisition card to the computer, the voltage signals generated by the energy harvester are processed through the DHDAS dynamic signal data acquisition system to obtain accurate voltage signals, and Figure 5 . By applying different magnitudes of impact forces to the energy harvester, it can be concluded that in the range of 0 - 250 N, as the impact pressure increases, the maximum output voltage of the energy harvester continuously rises because the deformation amount of the energy harvester gradually increases and the magnetic domains of the internal magnetostrictive layer are fully utilized. After the impact pressure exceeds 250 N, the magnetic domains of the internal magnetostrictive layer are completely utilized and the maximum output voltage tends to be stable, about 1000 mV.

[0056] Next, a mechanical stability test is conducted on the energy harvester. As Figure 6As shown, under the condition of an impact force of 1000 N and 100 consecutive impacts, the variation of the maximum output voltage of the energy harvester is presented. The ordinate represents the percentage of the voltage amplitude of every 10 impacts to the voltage amplitude of the first impact. The observation results show that in the test with 100 impact times, the output voltage of the energy harvester still remains relatively stable, and the maximum output voltage is about 96% of the voltage amplitude of the first impact. This indicates that the energy harvester has good mechanical properties and force recovery performance.

[0057] Matters not covered by this invention are well-known technologies.

Claims

1. A cross-bending magnetostrictive-epoxy resin composite energy harvester, characterized in that: The energy harvester includes a magnetostrictive-epoxy composite structure, a pickup coil, and a bias magnet; The magnetostrictive-epoxy resin composite structure is a cross-bend structure, and a pickup coil is wound around each of the four ends of the structure; the bias magnet is fixed directly above the pickup coil; The magnetostrictive-epoxy resin composite structure comprises a magnetostrictive layer and a fixed layer; wherein the magnetostrictive layer is embedded in the fixed layer; The cross-bend structure comprises two vertically intersecting arc-shaped strips, and the four protruding ends have equal lengths and widths; The magnetostrictive layer is an iron-cobalt-vanadium alloy sheet.

2. The cross-bending magnetostrictive-epoxy resin composite energy harvester according to claim 1, characterized in that: The iron-cobalt-vanadium alloy is Fe49-Co49-V2; The pickup coil is made of insulated copper enameled wire, with 500 to 700 turns; The material of the bias magnet is N35 neodymium iron boron permanent magnet.

3. The cross-bending magnetostrictive-epoxy resin composite energy harvester according to claim 1, characterized in that: The two arc-shaped strips have the same size, with a length of 15 to 18 cm, a width of 4 to 6 cm, and a radius of curvature of 15 to 20 cm; Thickness: 3-5 mm; The magnetostrictive layer has the same cross-bend structure, with a length of 11 to 13 cm, a width of 2.5 to 3.5 cm, and a thickness of 0.3 to 0.7 mm; the radius of curvature of the arc is 18 cm; the magnetostrictive layer and the fixed layer have the same center; The size of the bias magnet is 5cm×3cm×0.5cm.

4. The cross-bending magnetostrictive-epoxy resin composite energy harvester according to claim 1, characterized in that: The length of the magnetostrictive-epoxy composite structure occupied by each pickup coil winding is 18 to 22% of the length of the magnetostrictive-epoxy composite structure; The diameter of the insulated copper enameled wire ranges from 0.15 to 0.25 mm.

5. The cross-bending magnetostrictive-epoxy resin composite energy harvester according to claim 1, characterized in that: The method for preparing the magnetostrictive-epoxy resin composite structure comprises the following steps: The epoxy resin matrix and the curing agent are mixed in a mass ratio of 3:1, put into a blender and stir evenly for 10 to 15 minutes, let stand for 8 to 16 minutes, then pour into a specific mold, and cure at room temperature for 6 to 8 hours to obtain a precursor solution, then put the Fe-Co-V alloy sheet into the incompletely cured precursor solution, and then pour the precursor solution of the same composition into the mold to cover the surface of the Fe-Co-V alloy sheet, let stand for 2 to 4 hours, take out the incompletely cured composite structure, apply external force around the composite structure to deform it into an arc, and then put it into a heating box, set the temperature to 35 to 45°C and continue to cure for 10 to 15 hours, and take it out after it is completely cured and cool it at room temperature for 30 to 90 minutes to obtain a magnetostrictive-epoxy resin composite structure; The epoxy resin matrix is ​​bisphenol A; the curing agent is polyether amine or modified amine.

Images