Coupling type multi-direction broadband piezoelectric energy collecting device

Abstract

The invention discloses a coupling type multi-direction broadband piezoelectric energy collecting device, and belongs to the technical field of vibration energy harvesting. The invention aims to solve the problems of narrow effective working range and single vibration direction of the traditional piezoelectric energy collection device. The energy collecting device is composed of two different piezoelectric vibrators, the piezoelectric vibrators are fixed on a connecting shaft through bolts and nuts in different directions, and the connecting shaft is fixedly connected with a wire clamp. When vibration occurs, the vibration is transmitted to the two piezoelectric vibrators through the wire clamp and the connecting shaft; the piezoelectric plate is subjected to alternate stress and strain, and mechanical energy is converted into electric energy to be supplied to microelectronic equipment. The inherent frequency of the piezoelectric vibrator can be adjusted by changing the length and the distance between the main beam and the auxiliary beam and the mass of the mass block at the tail end of the auxiliary beam. The multi-directional energy harvesting device is flexible in design, good in environmental adaptability, capable of achieving energy harvesting in multiple vibration frequency intervals in multiple directions, and capable of being widely applied to energy harvesting in the vibration fields of high-altitude electric wires, aerial optical cables, bridge cables and the like.

Description

Technical Field

[0001] The invention relates to a piezoelectric energy collection device, in particular to a coupled multi-directional broadband piezoelectric energy collection device, belonging to the technical field of vibration energy capture. Background Art

[0002] With the continuous progress of human society and the accelerated integration of industrialization and informatization, the Internet of Things technology is rapidly becoming popular. The development of the Internet of Things will inevitably drive the development of sensors, and with it comes the problem of the continuous function of low-power sensor networks. At present, most sensors still use chemical batteries as the main energy supply method, but the service life of chemical batteries is limited, and the performance of batteries will gradually decline over time. Secondly, chemical batteries perform poorly under extreme environmental conditions and have certain negative impacts on the environment during production and processing. In order to overcome these shortcomings, researchers are exploring new energy supply methods, among which the use of vibration to convert mechanical energy into electrical energy is considered to be an effective alternative. At present, vibration energy harvesting devices can be divided into electromagnetic, piezoelectric and electrostatic types. Among them, piezoelectric energy harvesting has many advantages over other energy supply forms, such as simple structure, high energy density, and easy miniaturization, and has broad research and application prospects.

[0003] However, most of the current piezoelectric energy harvesting devices have a narrow operating frequency band, and it is necessary to ensure that the environmental vibration is maintained near the resonant frequency of the energy harvesting device to effectively harvest energy, such as the literature "XU WD, AO HR, ZHOU NN, et al. Analysis of Output Performance of a Novel Symmetrical T-Shaped Trapezoidal Micro Piezoelectric Energy Harvester Using a PZT-5H[J]. Micromachines, 2022, 13(2)." and "SU WJ, TSENG C H. Design and Analysis of an Extended Simply Supported Beam Piezoelectric Energy Harvester[J]. Sensors, 2023, 23(13).". Although their output power is high, there is only one effective energy harvesting interval within a certain vibration frequency range and the frequency band is narrow. The resonant frequency gap between adjacent modes is too large, which is not suitable for working environments with continuous vibration within a certain vibration range.

[0004] Secondly, relevant scholars often combine frequency reduction technology to study multi-directional piezoelectric energy harvesting devices to solve the problem that the effective working frequency of piezoelectric energy harvesting devices is generally higher than the frequency in the actual working environment. However, the current frequency reduction method often leads to a poor energy capture effect of piezoelectric energy harvesting devices, and the output power is mostly at the μW level, as shown in the literature "[1] WEI XX, ZHAO HB, YU JJ, et al. A Tower-Shaped Three-Dimensional Piezoelectric Energy Harvester for Low-Level and Low-Frequency Vibration [J]. International Journal of Precision Engineering and Manufacturing-Green Technology, 2021, 8 (5): 1537-50." and "ABDELKAREEM MAA, JING XJ, ELDALY ABM, et al. 3-DOF X-structured piezoelectric harvesters for multidirectional low-frequency vibration energy harvesting [J]. Mechanical Systems and Signal Processing, 2023, 200.", etc., are difficult to meet the power supply requirements of some low-power sensors.

[0005] At present, the operating frequency of most piezoelectric energy harvesting devices cannot be changed as the structural dimensions are determined. Once the working environment changes, the piezoelectric energy harvesting device with a fixed frequency may not be able to effectively collect energy. For example, the literature "CAOY T, CAO DQ, HE GQ, et al. Vibration analysis and distributed piezoelectric energy harvester design for the L-shaped beam [J]. European Journal of Mechanics a-Solids, 2021, 87." etc., which greatly limits the application of piezoelectric energy harvesting devices. Summary of the invention

[0006] The purpose of the present invention is to provide a coupled multi-directional broadband piezoelectric energy harvesting device to solve the problems of traditional piezoelectric energy harvesting devices having a single energy harvesting direction, a narrow effective energy harvesting range and the inability to adjust the device.

[0007] A coupled multi-directional broadband piezoelectric energy harvesting device includes two different piezoelectric vibrators, each of which is composed of a main beam, an auxiliary beam, a piezoelectric sheet, a main beam end fixture, an auxiliary beam root fixture and an auxiliary beam end mass block;

[0008] The main beam is fixedly connected to the end clamp of the main beam by bolts and nuts, and the auxiliary beam is fixed to the root clamp of the auxiliary beam by bolts and nuts, and then coupled with the main beam by connecting the root clamp of the auxiliary beam with the end clamp of the main beam; the piezoelectric vibrator is fixed to the connecting part in different directions by bolts, nuts and flange clamps.

[0009] Preferably: the wire clamp (long) and the wire clamp (short) are provided with through holes, bolts pass through the connecting holes on the connecting piece and the through holes of the wire clamp (long) and cooperate with nuts to achieve a fixed connection between the two, and the remaining through holes of the wire clamp (long) and the through holes of the wire clamp (short) are passed through by bolts and cooperate with nuts to achieve the connection between the cable and the piezoelectric energy collection device.

[0010] Preferably: a through hole is opened at the root of the main beam, and bolts pass through the through hole at the root of the main beam and the through hole of the flange clamp and cooperate with nuts to fix the main beam on the flange clamp; 12 through holes are opened on the flange of the flange clamp and the connecting piece, and the direction of the piezoelectric vibrator can be changed every 30° by rotating the flange clamp. At the same time, the convex stopper of the flange clamp cooperates with the through hole of the connecting piece to ensure the correct position during assembly, and the bolts pass through the direction adjustment hole of the clamp and the flange hole of the connecting piece and cooperate with nuts to fix the position and direction of the piezoelectric vibrator.

[0011] Preferably: the main beam and the auxiliary beam are of equal width, the width of the piezoelectric sheet is slightly smaller than the width of the two beams, and the piezoelectric sheet is pasted to the roots of the main beam and the auxiliary beam by epoxy resin conductive adhesive. When the root of the piezoelectric beam is subjected to a large stress change, the piezoelectric sheet converts mechanical energy into electrical energy and outputs it through the wire.

[0012] Preferably: a through hole is opened at the end of the main beam, and bolts pass through the through hole at the end of the main beam and the through hole of the clamp at the end of the main beam and cooperate with nuts to fix the clamp at the end of the main beam on the main beam; similarly, a through hole is opened at the root of the auxiliary beam, and bolts pass through the through hole at the root of the auxiliary beam and the through hole of the clamp at the root of the auxiliary beam and cooperate with nuts to fix the auxiliary beam on the clamp at the root of the auxiliary beam; the pointer on the clamp at the root of the auxiliary beam is aligned with the scale on the clamp at the end of the main beam according to environmental requirements, and then the position is fixed by bolts passing through the countersunk hole on the auxiliary beam and the waist-shaped hole on the main beam; loosen the bolts and nuts, and change the distance between the two beams by adjusting the position of the clamp at the root of the auxiliary beam. At the same time, the mass block at the end of the auxiliary beam is also adjustable, thereby realizing the function of changing the working frequency of the energy collection device according to environmental changes.

[0013] Compared with existing products, the present invention has the following effects:

[0014] 1. A coupled multi-directional broadband piezoelectric energy harvesting device is inspired by a torque vibration damper. Two piezoelectric vibrators are connected in different directions. The piezoelectric vibrators are subjected to vibrations in different directions, converting mechanical energy into electrical energy, so that energy can be captured in multiple directions.

[0015] 2. The structural dimensions of the two piezoelectric vibrators of the present invention can be adjusted. Changing the length of the main beam directly affects the first-order natural frequency of the piezoelectric vibrator. Changing the length ratio of the main beam and the auxiliary beam affects the resonant frequency of the first-order bending vibration mode of the auxiliary beam. Adjusting the spacing between the two beams will greatly affect the resonant frequency of the torsional vibration mode of the piezoelectric vibrator. The working frequency of each piezoelectric vibrator can be designed according to the working environment, so that the present invention has 4 effective energy capture intervals within a certain vibration frequency band, thereby broadening the working frequency band of the piezoelectric energy harvesting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a coupled multi-directional broadband piezoelectric energy harvesting device;

[0017] Figure 2 It is a schematic diagram of the explosion of a piezoelectric vibrator;

[0018] Figure 3 It is an exploded schematic diagram of the connection part;

[0019] Figure 4 It is a schematic diagram of the simulation of the first three modes of a coupled multi-directional broadband piezoelectric energy harvesting device;

[0020] Figure 5 It is the frequency-open circuit voltage diagram of the piezoelectric vibrator part at 0° under 0.2g vertical excitation;

[0021] Figure 6 It is the frequency-open circuit voltage diagram under 0.2g vertical excitation when the piezoelectric vibrator part is 150°;

[0022] In the figure: 1—wire clamp (short), 2—wire clamp (long), 3—connecting piece, 4—flange clamp, 5—clamp at the end of the main beam, 6—clamp at the root of the auxiliary beam, 7—piezoelectric sheet, 8—auxiliary beam, 9—mass block at the end of the auxiliary beam, 10—main beam, 11—through hole at the end of the main beam, 12—through hole at the root of the auxiliary beam, 13—through hole of the clamp at the root of the auxiliary beam, 14—pointer, 15—countersunk hole, 16—waist-shaped hole, 17—through hole of the clamp at the end of the main beam, 18—scale, 19—through hole of the connecting piece, 20—flange hole of the connecting piece, 21—through hole of the wire clamp (short), 22—connecting hole, 23—through hole of the wire clamp (long), 24—clamp direction adjustment hole, 25—convex stopper, 26—through hole of the flange clamp, 27—through hole at the root of the main beam. DETAILED DESCRIPTION

[0023] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] like Figures 1 to 3 As shown, a coupled multi-directional broadband piezoelectric energy harvesting device according to the present invention comprises two different piezoelectric vibrators and a connecting part;

[0025] The specific piezoelectric vibrator includes: a main beam 10, an auxiliary beam 8, a piezoelectric sheet 7, a main beam end clamp 5, an auxiliary beam root clamp 6 and an auxiliary beam end mass block 9; the specific connecting parts include: a wire clamp (long) 1, a wire clamp (short) 2, a connector 3 and a flange clamp 4.

[0026] Further: the wire clamp (long) 1 and the wire clamp (short) 2 are provided with through holes, and bolts pass through the connecting hole 22 on the connecting piece and the wire clamp (long) through hole 23 and cooperate with nuts to achieve a fixed connection between the two, and the remaining wire clamp (long) through hole 23 and wire clamp (short) through hole 21 are passed through by bolts and cooperate with nuts to achieve the connection between the cable and the piezoelectric energy collection device.

[0027] Further: a through hole is opened at the root of the main beam 10, and the bolts and nuts are used to fix the main beam 10 on the flange clamp 4 through the through hole 27 at the root of the main beam and the through hole 26 of the flange clamp; 12 evenly distributed through holes are opened on the flange of the flange clamp 4 and the connecting part 3, and the bolts and nuts are used to fix the flange clamp 4 to the connecting part 3 through the clamp direction adjustment hole 24 and the connecting part flange hole 20, so that the direction of the piezoelectric vibrator can be changed every 30°; at the same time, the convex stop 25 of the flange clamp 4 cooperates with the connecting part through hole 19 to ensure the correct position during assembly and maintain stability.

[0028] Further: the main beam 10 and the auxiliary beam 8 are of equal width, the width of the piezoelectric sheet 7 is slightly smaller than the width of the two beams, and the piezoelectric sheet 7 is pasted to the roots of the main beam 10 and the auxiliary beam 8 by epoxy resin conductive glue. When the root of the piezoelectric beam is subjected to a large stress change, the piezoelectric sheet 7 converts mechanical energy into electrical energy and outputs it through the wire.

[0029] Further: a through hole is opened at the end of the main beam 10, and bolts pass through the through hole 11 at the end of the main beam and the through hole 17 of the clamp at the end of the main beam and cooperate with nuts to fix the clamp 5 at the end of the main beam on the main beam; similarly, a through hole is opened at the root of the auxiliary beam 8, and bolts pass through the through hole 12 at the root of the auxiliary beam and the through hole 13 of the clamp at the root of the auxiliary beam and cooperate with nuts to fix the auxiliary beam 8 on the clamp 6 at the root of the auxiliary beam; the pointer 14 on the clamp 6 at the root of the auxiliary beam is aligned with the scale 18 on the clamp at the end of the main beam according to environmental requirements, and then the position is fixed by bolts passing through the countersunk hole 15 on the auxiliary beam and the waist-shaped hole 16 on the main beam; loosen the bolts and nuts, and change the distance between the two beams by adjusting the position of the clamp 6 at the root of the auxiliary beam. At the same time, the mass block 9 at the end of the auxiliary beam is also adjustable, thereby realizing the function of changing the working frequency of the energy collection device according to environmental changes.

[0030] further: Figure 4This is a schematic diagram of the simulation of the first three modes of the piezoelectric vibrator part of the present invention. The second and third modes of the piezoelectric vibrator can be exchanged by changing the distance between the double beams and the length ratio between the double beams. Due to the characteristics of piezoelectric materials, piezoelectric energy is usually collected under the bending mode of the beam. Therefore, the structure can be reasonably adjusted to collect energy under different environmental frequencies.

[0031] further: Figure 5 This is the frequency-open-circuit voltage diagram of the piezoelectric vibrator part of the present invention when it is 0° (parallel to the ground, with the auxiliary beam on top) under 0.2g vertical excitation. Due to the particularity of the structure, the piezoelectric vibrator can achieve good energy capture effects in both the first-order and second-order bending modes. When the excitation frequency is around 9.8Hz, the maximum open-circuit voltage of the main beam exceeds 35V, and at the same time, the auxiliary beam is driven to generate a peak voltage of more than 5V; when the excitation frequency is around 19Hz, both the main beam and the auxiliary beam can generate a large voltage, and their maximum open-circuit voltages are both over 15V.

[0032] further: Figure 6 This is the frequency-open-circuit voltage diagram of the piezoelectric vibrator part of the present invention under 0.2g vertical excitation when the angle is 150°. The piezoelectric vibrator can achieve good energy capture effects in both the first-order and second-order bending modes. The excitation frequency is around 9.8Hz, and the power generation of the piezoelectric vibrator is similar to that at 0°. When the excitation frequency is around 18-19Hz, the maximum open-circuit voltage of the main beam and the auxiliary beam exceeds 7V. Although the power generation level is lower than that at 0°, the power generation frequency band is broadened, which reflects the superiority of the present invention in the field of multi-directional energy collection.

[0033] This implementation is only an exemplary description of this patent and does not limit its protection scope. Those skilled in the art may also make partial changes to it, but they do not exceed the spirit of this patent and are all within the protection scope of this patent.

Claims

1. A coupled multi-directional broadband piezoelectric energy harvesting device, characterized in that: The present invention is inspired by a torque vibration damper and is composed of two different piezoelectric vibrators and a connecting part. Each piezoelectric vibrator includes: a main beam (10), an auxiliary beam (8), a piezoelectric sheet (7), a main beam end clamp (5), an auxiliary beam root clamp (6) and an auxiliary beam end mass block (9). The present invention aims to provide a piezoelectric energy collection device that can be applied to vibration environments such as high-altitude wires, overhead optical cables and bridge cables. When the environmental frequency is close to the first three natural frequencies of the piezoelectric vibrator, a large alternating stress is generated on the piezoelectric sheet (7) at the root of the main beam (10) and the auxiliary beam (8). According to the positive piezoelectric effect, the mechanical energy of the piezoelectric vibrator is converted into electrical energy.

2. A coupled multi-directional broadband piezoelectric energy harvesting device according to claim 1, characterized in that: A through hole is formed at the root of the main beam (10), and bolts and nuts are used to fix the main beam (10) to the flange clamp (4) through the through hole (27) at the root of the main beam and the through hole (26) of the flange clamp; 12 evenly distributed through holes are formed on the flange of the flange clamp (4) and the connecting piece (3), and bolts and nuts are used to fix the flange clamp (4) to the connecting piece (3) through the clamp direction adjustment hole (24) and the connecting piece flange hole (20), so that the direction of the piezoelectric vibrator can be changed every 30 degrees; at the same time, the convex stop (25) of the flange clamp (4) cooperates with the connecting piece through hole (19), thereby ensuring the correct position during assembly and maintaining stability.

3. The coupled multi-directional broadband piezoelectric energy harvesting device according to claim 1, characterized in that: The end of the main beam (10) is provided with a through hole, and bolts and nuts are passed through the main beam end through hole (11) and the main beam end fixture through hole (17) to fix the main beam end fixture (5) on the main beam (10); at the same time, the root of the auxiliary beam (8) is provided with a through hole, and bolts and nuts are passed through the auxiliary beam root through hole (12) and the auxiliary beam root fixture through hole (13) to fix the auxiliary beam (8) on the auxiliary beam root fixture (6); the longer end of the main beam end fixture (5) is provided with a waist-shaped hole (16) and is engraved with a linear scale (18), and the auxiliary beam root fixture (6) adjusts the distance between the two beams according to the pointer (14) above, and is fixed to the main beam end fixture (5) by bolts and nuts passing through the countersunk hole (15) and the waist-shaped hole (16).

4. The coupled multi-directional broadband piezoelectric energy harvesting device according to claim 1, characterized in that: Due to the particularity of the structure, the resonant frequency of the bending vibration mode of the auxiliary beam (8) is not much different from the resonant frequency of the torsional vibration mode of the piezoelectric vibrator. By fixing the length of the main beam (10) unchanged and reducing the length ratio of the main beam to the auxiliary beam, the resonant frequency of the bending vibration mode of the auxiliary beam (8) can be effectively reduced; increasing the distance between the two beams can effectively reduce the resonant frequency of the torsional vibration mode of the piezoelectric vibrator; increasing the mass block at the end of the auxiliary beam can effectively reduce the first three natural frequencies of the piezoelectric vibrator and increase the output power of the auxiliary beam when it is in bending resonance.

5. The coupled multi-directional broadband piezoelectric energy harvesting device according to claim 1, characterized in that: The directions of the piezoelectric vibrators at both ends of the connecting member (3) are adjustable to achieve multi-directional energy collection; by changing the length and spacing of each piezoelectric vibrator main beam (10) and auxiliary beam (8), and the mass of the auxiliary beam end mass block (9), the magnitude of the first three natural frequencies of each piezoelectric vibrator is reasonably adjusted, so that the present invention can achieve energy collection in multiple vibration frequency ranges, effectively broadening the working frequency band of the energy collection device.

Images