Magnetostriction-piezoelectric composite array for collecting human motion energy

Abstract

The invention relates to a magnetostriction-piezoelectric composite array for collecting human motion energy. The composite array comprises a movable permanent magnet, a spring, a shell, a magnetoelectric composite sheet and a bias magnet, the shell comprises a bottom plate and four walls, a rectangular cylinder is arranged in the middle of the left side wall of the shell, and a vertical plate is arranged on the outer side of the right wall of the rectangular cylinder; a groove is formed below the vertical plate, and a bias magnet is arranged in the groove; the rear wall of the vertical plate, the inner side of the front wall of the shell and the inner side of the rear wall of the shell are each fixedly provided with a magnetoelectric composite sheet, and the horizontal projection positions of the three magnetoelectric composite sheets are overlapped. The movable permanent magnet is arranged in the middle of the rectangular cylinder in the shell, and the springs are distributed on the upper surface and the lower surface of the movable permanent magnet respectively. The device has the advantages of low cost, large output signal, miniaturization, easiness in carrying, high stability and the like, and is extremely suitable for the field of human motion energy collection.

Description

Technical field:

[0001] The present invention relates to the field of human body motion energy collection, and in particular to a magnetoelectric composite energy collector capable of collecting human body motion energy. Background technology:

[0002] With the progress of society and the development of science and technology, the miniaturization and diversification of functions of microelectronic devices have led to the emergence of a large number of various intelligent electronic devices. As the degree of intelligence and integration of electronic devices becomes higher and higher, the required energy consumption is also increasing, so the power supply problem has become the main problem in the design of these devices. Because traditional battery power supply is limited by life and needs to be replaced regularly, and it is chemically toxic, it is easy to cause environmental pollution. Therefore, people are trying to explore the energy that can be used from the surrounding environment, including light energy, thermal energy, and sound wave vibration energy. In fact, the human body itself is also a huge energy warehouse, including thermal energy, mechanical energy, etc. As people pay more and more attention to human health, replacing traditional batteries by collecting human energy has become a new research hotspot. At present, human motion energy collection technology is mainly divided into electromagnetic, piezoelectric, and triboelectric. Electromagnetic is generally larger in size, but the output voltage is small; the pressure resistance of the materials used for triboelectric is poor, and long-term bending deformation will cause mechanical damage and reduced output performance; piezoelectric materials are brittle and charge leakage is prone to occur after long-term work.

[0003] Magnetoelectric (ME) is a widely used multifunctional composite material that has both magnetostriction and piezoelectricity. The output voltage is generated mainly through the strong coupling of magnetostriction effect and piezoelectric effect under changing magnetic field. Therefore, ME materials have the advantages of large output voltage, small bending deformation, long service life, and easy to carry. It has good application prospects in fields such as magnetic field sensors and energy collection. At present, magnetoelectric composite energy collection technology is just in its infancy, for example: Patent No. CN 216390824 U is a magnetoelectric motion energy collector. This patent uses two Metglas / PIN-PMN-PT composite plates as core components, and realizes the collection of human motion energy through the changing magnetic field generated by the movable permanent magnet when the human body moves. However, the output capacity of the collector is low, and the PIN-PMN-PT piezoelectric material has just started research, and the cost is very expensive, which is not conducive to large-scale production and popularization. Summary of the invention:

[0004] The purpose of the present invention is to propose a magnetostrictive-piezoelectric composite array for human motion energy collection in view of the deficiencies in the current technology. The collector generates voltage by means of the magnetoelectric coupling effect, avoiding the performance degradation caused by collision and bending during movement, and adopts a new array structure. This innovative design fully improves the output capacity of the energy collector. At the same time, the use of a cheap magnetoelectric composite material with Fe-Co-V / PZT as the core effectively reduces the cost. Therefore, the present invention has the advantages of low cost, large output signal, miniaturization, easy to carry, strong stability, etc., and is extremely suitable for the field of human motion energy collection.

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

[0006] A magnetostrictive-piezoelectric composite array for human motion energy collection, the composite array comprising a movable permanent magnet, a spring, a housing, a magnetoelectric composite sheet and a bias magnet;

[0007] The outer shell is in the shape of a cubic box, and the upper part of the box is open; it comprises a bottom plate and four walls, a rectangular tube is arranged in the middle of the left side wall, and a vertical plate is arranged on the outer side of the right wall of the rectangular tube; there is a groove under the vertical plate, and a bias magnet is arranged in the groove;

[0008] A magneto-electric composite sheet is fixed to each of the rear wall of the vertical plate, the inner side of the front wall of the shell, and the inner side of the rear wall of the shell, and the horizontal projection positions of the three magneto-electric composite sheets overlap;

[0009] A movable permanent magnet is arranged in the middle of the rectangular tube in the shell, and a spring is distributed on the upper and lower surfaces of the movable permanent magnet;

[0010] The magnetostrictive-piezoelectric composite sheet comprises two magnetostrictive layers and one piezoelectric layer; the two magnetostrictive layers are respectively bonded to the upper and lower surfaces of the piezoelectric layer by epoxy resin glue;

[0011] The magnetostrictive layer is a magnetostrictive sheet made of Fe-Co-V, Fe-Ni, Fe-Ga or Terfenol;

[0012] The piezoelectric layer is a piezoelectric thin film made of piezoelectric ceramics (PZT); the length and width are consistent with the magnetostrictive layer;

[0013] The movable magnet is made of N52 neodymium iron boron permanent magnet;

[0014] The material of the bias magnet is N52 neodymium iron boron permanent magnet;

[0015] The size of the magnetoelectric composite sheet is 43mm×13mm;

[0016] The force sensitive layer is a piezoelectric sheet made of PZT with a thickness ranging from 0.5 to 1 mm;

[0017] The thickness of the magnetostrictive layer ranges from 0.1 to 0.3 mm;

[0018] The outer shell has a size of 25mm×25mm×60mm, and the rectangular tube has a size of 5.5mm×5mm×51mm; a buckle or a top cover is provided at the top end of the rectangular tube in the outer shell.

[0019] The movable magnet has a size of 5 mm × 5 mm × 14 mm;

[0020] The size of the bias magnet is 20mm×10mm×7mm.

[0021] The essential features of the present invention are:

[0022] At present, various motion energy harvesters at home and abroad are mostly piezoelectric and electromagnetic. However, piezoelectric materials are brittle, and long-term bending and deformation will cause mechanical damage and reduced output performance. The electromagnetic output signal is generally small. These technologies need further development, and magnetoelectric composite energy harvesting is in its infancy. The output power is generally low and the cost is high, which is not conducive to large-scale production and popularization.

[0023] The present invention adopts the lower-cost Fe-Co-V / PZT magnetoelectric composite material as the core component and designs an array structure. Under mechanical excitation such as human movement, the movable magnet moves up and down, and the magnetostrictive layer will produce mechanical deformation under the changing magnetic field, and then exert stress on the piezoelectric layer, and the piezoelectric layer generates an induced voltage, which meets a series of requirements such as miniaturization and large output signal, and is extremely suitable for the field of human movement energy collection.

[0024] The main principle is: under mechanical excitation such as human movement, the movable permanent magnet will move up and down, and the springs distributed up and down will reduce the energy loss during the movement of the movable permanent magnet, making the magnet move more violently, thereby generating a changing magnetic field inside the shell. The magnetostrictive layer will produce mechanical deformation under the changing magnetic field, and then exert stress on the piezoelectric layer, at which time the piezoelectric layer generates an induced voltage. The bias magnet provides a bias magnetic field, which will further excite the magnetostrictive layer to produce more magnetic domains, further increasing its mechanical deformation.

[0025] The beneficial effects of the present invention are:

[0026] 1. The core component of the energy collector of the present invention is Fe-Co-V / PZT magnetoelectric composite material. Compared with piezoelectric and triboelectric, it relies on magnetoelectric coupling effect to generate voltage, avoiding the performance degradation caused by collision and bending during movement, so it has better mechanical properties. Improved mechanical properties correspond to longer service life, no aging problem, and more reliable working performance. Compared with Metglas / PIN-PMN-PT magnetoelectric composite material, it has lower cost, broader prospects, and is more in line with the requirements of production economy.

[0027] 2. Compared with the electromagnetic energy collector, which has the characteristics of fixed placement and large size, the overall volume of the present invention is small, which meets the requirements of miniaturization and can be carried around. It is expected to provide continuous power supply for wearable electronic devices and is suitable for large-scale promotion and use.

[0028] 3. Based on the problem of low output signal in the field of magnetoelectric composite energy collection, the present invention designs an array structure, and effectively improves the output capacity of the magnetostrictive-piezoelectric composite array by connecting multiple magnetoelectric composite sheets in series. Description of the drawings:

[0029] Figure 1 It is a top view of the magnetostrictive-piezoelectric composite array for human motion energy harvesting;

[0030] Figure 2 for Figure 1 A cross-sectional view along the center position;

[0031] Figure 3 is a schematic diagram of the housing;

[0032] Figure 4 is a schematic diagram of a magneto-electric composite sheet;

[0033] Figure 5 A comparison of magnetoelectric coefficients of a single magnetoelectric composite sheet and a magnetoelectric composite array at different frequencies;

[0034] Figure 6 The magnetoelectric coefficient comparison diagram of a single magnetoelectric composite sheet and a magnetoelectric composite array under different DC bias magnetic fields;

[0035] In the figure: 1- movable permanent magnet; 2- spring; 3- housing; 4- magnetoelectric composite sheet; 5- bias magnet; 6- first magnetostrictive layer; 7- piezoelectric layer; 8- second magnetostrictive layer; Specific implementation method:

[0036] The magnetostrictive-piezoelectric composite array uses the strong coupling of magnetostrictive effect and piezoelectric effect to achieve human body movement energy harvesting. Under mechanical excitation such as human body movement, the movable permanent magnet will move up and down. The springs distributed up and down reduce the energy loss during the movement of the movable permanent magnet, making the magnet movement more violent, thereby generating a changing magnetic field inside the shell. Due to the magnetostrictive effect, the magnetostrictive layer will produce mechanical deformation under the changing magnetic field, and then exert stress on the piezoelectric layer. Due to the piezoelectric effect, the piezoelectric layer generates an induced voltage at this time. The bias magnet provides a bias magnetic field, which will further excite the magnetostrictive layer to produce more magnetic domains, further increasing its mechanical deformation.

[0037] The invention is further described in detail below in conjunction with the figures. This embodiment is only a specific description of the invention and is not to be regarded as limiting the scope of protection.

[0038] The magnetostrictive-piezoelectric composite array structure for human body motion energy collection described in the present invention is as follows: Figure 1 and Figure 2 As shown, the collector includes a movable permanent magnet 1, a spring 2, a housing 3, a magneto-electric composite sheet 4 and a bias magnet 5;

[0039] The outer shell is in the shape of a cubic box (made of epoxy resin and 3D printed), the upper part of which is open and has a size of 25mm×25mm×60mm; it consists of a bottom plate and four walls, and the wall thickness of the four sides is 4.5mm; a rectangular tube is arranged in the middle of the left side wall, and a vertical plate is arranged on the outer side of the right wall of the rectangular groove; the bottom plate of the outer shell 3 is 1mm thick, and there is a groove at the center position under the bottom plate, and a bias magnet 5 is arranged in the groove;

[0040] A magnetoelectric composite sheet 4 is fixed to each of the rear wall of the vertical plate, the inner side of the front wall of the shell, and the inner side of the rear wall of the shell. The horizontal projection positions of the three magnetoelectric composite sheets 4 overlap. The spacing between adjacent composite sheets among the three magnetoelectric composite sheets 4 is the same.

[0041] A movable permanent magnet 1 is arranged in the middle of the rectangular tube in the shell, and a spring 2 is distributed on the upper and lower surfaces of the movable permanent magnet 1; the inner wall size of the rectangular tube is 5.5mm×5mm×51mm, and the outer horizontal plate size of the right wall of the rectangular tube is 12mm×1mm×46mm; Figure 3 As shown;

[0042] Under mechanical excitation such as human body movement, the movable permanent magnet will move up and down. The springs distributed up and down reduce the energy loss during the movement of the movable permanent magnet, making the magnet move more violently, thereby generating a changing magnetic field inside the outer shell. The magnetostrictive layer will produce mechanical deformation under the changing magnetic field, and then exert stress on the piezoelectric layer, at which time the piezoelectric layer generates an induced voltage.

[0043] The magnetostrictive-piezoelectric composite sheet comprises two magnetostrictive layers and one piezoelectric layer; the two magnetostrictive layers are respectively attached to the upper and lower surfaces of the piezoelectric layer by epoxy resin glue;

[0044] The magnetostrictive layer is a magnetostrictive sheet made of an iron-cobalt-vanadium alloy (Fe49-Co49-V2); the size is 43 mm×13 mm, and the thickness ranges from 0.1 to 0.3 mm (the thickness used in this embodiment is 0.2 mm). Figure 4 As shown;

[0045] The piezoelectric layer is a piezoelectric thin film made of piezoelectric ceramic (PZT); the size is consistent with the magnetostrictive layer, and the thickness ranges from 0.5 to 1 mm (the thickness used in this embodiment is 0.7 mm). Figure 4 As shown;

[0046] Due to the magnetostrictive effect, the magnetostrictive layer of the composite sheet will produce mechanical deformation under a changing magnetic field, which will then apply stress to the piezoelectric layer. Due to the piezoelectric effect, the piezoelectric layer will generate an induced voltage.

[0047] The movable magnet is made of N52 neodymium iron boron permanent magnet, and its size is 5mm×5mm×14mm;

[0048] The spring is made of stainless steel and is located above and below the movable magnet to reduce the energy loss during the movement of the movable permanent magnet, so that it can obtain greater kinetic energy;

[0049] The top end of the rectangular tube in the shell can also be closed by providing a buckle, a top cover, etc. (the present invention is sealed with a tape) to prevent the movable magnet from slipping out of the rectangular tube.

[0050] The bias magnet is made of N52 neodymium iron boron permanent magnet, and its size is 20mm×10mm×7mm;

[0051] The mechanism of action of the present invention is:

[0052] Under mechanical excitation such as human movement, the movable permanent magnet will move up and down. The springs distributed up and down reduce the energy loss during the movement of the movable permanent magnet, making the magnet move more violently, thereby generating a changing magnetic field inside the shell. Due to the magnetostrictive effect and the piezoelectric effect, the magnetostrictive layer will produce mechanical deformation under the changing magnetic field, and then exert stress on the piezoelectric layer, at which time the piezoelectric layer generates an induced voltage. The bias magnet provides a bias magnetic field, which will further excite the magnetostrictive layer to produce more magnetic domains, further increasing its mechanical deformation. The arrayed structure allows the output signals to be superimposed, further improving the output performance.

[0053] The method of use includes the following steps:

[0054] The lock-in amplifier (HF2LI) is connected to the computer, and the working state of the lock-in amplifier is set in the corresponding software of the computer, and a variable frequency sinusoidal voltage waveform is input to the solenoid. The solenoid is 300 mm long and the number of turns of the coil is 266. After receiving the voltage, the solenoid can generate AC magnetic fields of different sizes. The fixed magnetostrictive-piezoelectric composite sheet is located in the center so that it can work in a resonant state with free vibration at both ends. At this time, the magnetostrictive layer will sense the changing magnetic field, produce mechanical deformation, and then exert stress on the piezoelectric layer. Due to the piezoelectric effect, the piezoelectric layer generates an induced voltage at this time. A Gauss meter (Model 8050Gauss) with a probe is used to detect the magnetic field state of the magnetostrictive-piezoelectric composite sheet in the energized solenoid. Finally, the output voltage signal of the magnetostrictive-piezoelectric composite sheet is received by the lock-in amplifier and finally presented in the computer. The DC bias magnetic field during the experiment is provided by two NdFeB magnets fixed by the clamps on both sides of the coil.

[0055] The protocols and software involved in the present invention are all well-known technologies.

[0056] Figure 5 The figure shows the changes in the magnetoelectric coefficients of the two samples at different frequencies when the DC magnetic field is 27Oe and the AC magnetic field is 0.3Oe. It can be seen that as the AC frequency increases, the magnetoelectric coefficient shows an overall trend of first increasing and then decreasing. The value of a single magnetoelectric composite sheet reaches its maximum at an AC frequency of 44kHz, which is 11.4V cm-1Oe-1. It is worth noting that the magnetoelectric coefficient of the array structure is much larger than that of a single composite sheet. Its value is 27.8V cm-1Oe-1 (almost 3 times that of a single composite sheet). This is because the output voltages of the magnetoelectric composite sheets are connected in series and the values ​​are superimposed. This shows that the use of an array structure can effectively enhance the magnetoelectric coupling effect.

[0057] Figure 5 The optimal AC frequency corresponding to the samples in the two cases was determined by analysis. Based on this, the effect of the DC bias magnetic field on the magnetoelectric coefficients of the two samples was further analyzed. The results are as follows: Figure 6 As shown. It can be seen that: with the increase of the DC magnetic field, the magnetoelectric coefficient shows an overall trend of first increasing and then decreasing. The value of a single magnetoelectric composite sheet reaches the maximum at a DC magnetic field of 21Oe, which is 15V cm-1Oe-1. Among them, the magnetoelectric coefficient of the array structure is much larger than that of a single composite sheet. This shows that the array structure effectively enhances the magnetoelectric coupling effect and increases the output voltage of the magnetoelectric composite sheet. Since the positions of the composite sheets in the array structure are close and there is mutual inductive coupling, the optimal DC magnetic field value (~25Oe) is larger than that of a single composite sheet (~21Oe).

[0058] Matters not covered by the present invention are known technologies.

Claims

1. A magnetostrictive-piezoelectric composite array for human motion energy collection, characterized by: The composite array includes a movable permanent magnet, a spring, a housing, a magneto-electric composite sheet and a bias magnet; The outer shell is in the shape of a cubic box, and the upper part of the box is open; It consists of a bottom plate and four walls. A rectangular tube is arranged in the middle of the left wall. A vertical plate is arranged outside the right wall of the rectangular tube. A groove is arranged under the vertical plate, and a bias magnet is arranged in the groove. A magneto-electric composite sheet is fixed to each of the rear wall of the vertical plate, the inner side of the front wall of the shell, and the inner side of the rear wall of the shell, and the horizontal projection positions of the three magneto-electric composite sheets overlap; A movable permanent magnet is arranged in the middle of the rectangular tube in the shell, and a spring is distributed on the upper and lower surfaces of the movable permanent magnet; The magnetostrictive-piezoelectric composite sheet comprises two magnetostrictive layers and one piezoelectric layer; the two magnetostrictive layers are respectively adhered to the upper and lower surfaces of the piezoelectric layer by epoxy resin glue.

2. The magnetostrictive-piezoelectric composite array for human motion energy collection as claimed in claim 1, characterized in that: The magnetostrictive layer is a magnetostrictive sheet made of Fe-Co-V, Fe-Ni, Fe-Ga or Terfenol; The piezoelectric layer is a piezoelectric thin sheet made of piezoelectric ceramics (PZT); the length and width are consistent with those of the magnetostrictive layer.

3. The magnetostrictive-piezoelectric composite array for human motion energy collection as claimed in claim 1, characterized in that: The movable magnet is made of N52 neodymium iron boron permanent magnet; The material of the bias magnet is N52 neodymium iron boron permanent magnet.

4. The magnetostrictive-piezoelectric composite array for human motion energy collection as claimed in claim 1, characterized in that: The size of the magnetoelectric composite sheet is 43mm×13mm; The force sensitive layer is a piezoelectric sheet made of PZT with a thickness ranging from 0.5 to 1 mm; The thickness of the magnetostrictive layer ranges from 0.1 to 0.3 mm; The movable magnet has a size of 5 mm × 5 mm × 14 mm; The size of the bias magnet is 20mm×10mm×7mm.

5. The magnetostrictive-piezoelectric composite array for human motion energy collection as claimed in claim 1, characterized in that: The shell size is 25mm×25mm×60mm, and the rectangular tube size is 5.5mm×5mm×51mm.

6. The magnetostrictive-piezoelectric composite array for human motion energy collection as claimed in claim 1, characterized in that: The top end of the rectangular tube in the shell is provided with a buckle or a top cover.

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