CN106685263B - Bandwidth adjustable n×3 lattice vibration energy harvester based on mode separation technology - Google Patents

Abstract

The invention relates to an environmental energy collection device in the technical field of micro-energy, in particular to a bandwidth-adjustable n×3 lattice vibration energy collector based on modal separation technology. A bandwidth-adjustable n×3 lattice vibration energy harvester based on modal separation technology, including a flexible frame main beam structure, a piezoelectric cantilever beam and a mass block; the flexible frame main beam structure is a rectangle, and the upper surface of the rectangle is along the axis There are n-1 hollow rectangular holes of equal size and the same spacing in sequence in the direction, forming n rows of flexible main beams, where n≥2; each flexible main beam is pasted and fixed with the same number of piezoelectric cantilever beams; A mass is attached to the floating end of each piezoelectric cantilever beam. By increasing or decreasing the row number n of the piezoelectric cantilever beam, and simultaneously changing the size of the piezoelectric cantilever beam and the mass block, the invention can timely adjust the effective frequency bandwidth of the system, improve the continuity and stability of the output of the energy harvester, and enhance the vibration. Environmental adaptability of energy harvesters.

Description

Bandwidth adjustable n×3 lattice vibration energy harvester based on mode separation technology

technical field

The invention relates to an environmental energy collection device in the technical field of micro-energy, in particular to an n×3 lattice vibration energy collector with adjustable bandwidth based on modal separation technology.

Background technique

With the wide application and rapid development of wireless mobile sensing technology in field environment, working condition monitoring and portable medical electronic systems, how to supply power to these electronic devices used in special fields has become a key issue to further promote their applications. To get rid of the constraints of traditional energy supply methods such as large size, short lifespan of chemical batteries, and difficulty in connecting wired power sources, collecting energy from the surrounding environment of the sensor to directly supply power to the system has become a research hotspot in the application field of wireless mobile sensing technology.

Vibration can widely exist in transportation (cars, aircraft and other means of transport and rails), industrial and mining equipment (large coal machines, CNC machine tools), engineering construction (bridges, buildings) and biological activities and other application environments. Compared with environmental energy forms such as solar energy and wind energy, vibration energy has obvious power supply advantages for mobile portable wireless sensors in the above application environments. However, the traditional vibration energy harvester has narrow frequency band, low energy conversion efficiency and low output power, and currently cannot meet the power supply requirements of wireless mobile sensor devices. How to improve the output power of the energy harvester, widen the collection frequency band and make it match the vibration frequency of the environment is the key problem to be solved urgently in the field of vibration energy harvesting.

The Chinese patent with Announcement No. CN 103346696 A designs an array-type piezoelectric and electromagnetic composite energy harvester. The array structure widens the energy harvesting frequency width and improves the energy conversion efficiency, but the combination of piezoelectric and electromagnetic makes the The vibration structure is complex, and it is not easy to debug and process. The Chinese patent with the announcement number of CN 103023378 A proposes a broadband multi-directional vibration energy harvester, which broadens the frequency band through energy harvesting of 6 T-shaped cantilever beams in multiple directions, but this device is relatively bulky and complex in structure. , is not easy to achieve. The Chinese patent with Announcement No. CN 102931340 A designs a broadband miniature piezoelectric vibration energy harvester, which utilizes multiple sets of different cantilever beam arrays to achieve a wider frequency band output, but the micromachining process is complicated and the manufacturing cost is high . In 2008, Xue et al. proposed an energy harvesting structure with multiple piezoelectric bimorphs in series and in parallel, using different thicknesses of each bimorph to obtain different first-order resonance frequencies, so that all first-order resonance frequencies are very close to each other. to increase the bandwidth of the collector. This method significantly broadens the operating frequency band, but its operating frequency range (90-110 Hz) is still higher than the frequency of vibration sources in some environments (bridges: 7-10 Hz, buildings: 15-20 Hz, rotating machinery: 43-50 Hz) Hz, animal activity: 1-45 Hz). Based on this, the design of a vibration energy harvester with low frequency, wide frequency band, high energy conversion efficiency, high power and stable output, and easy processing is particularly important.

SUMMARY OF THE INVENTION

In order to solve the problems of narrow working frequency band, low energy conversion efficiency and low output power of the existing energy harvester, the present invention proposes a bandwidth-adjustable n×3 lattice vibration energy harvester vibration pickup structure based on modal separation technology, The structure can not only adjust and widen the frequency band range of the collector, but also adopts a lattice structure design, which can effectively improve the energy conversion efficiency and output power.

The technical scheme adopted in the present invention is: a bandwidth-adjustable n×3 lattice vibration energy harvester based on modal separation technology, comprising a flexible frame main beam structure, a piezoelectric cantilever beam and a mass block; the flexible frame main beam The structure is a rectangle, a center line of the rectangle is selected as the axis, and n-1 hollow rectangular holes of equal size and the same spacing are opened on the rectangle in sequence along the axis direction, and the solid parts of all hollow rectangular holes along the axis direction are used as Flexible main beams, forming n rows of flexible main beams, where n≥2; multiple piezoelectric cantilever beams of the same number are pasted and fixed on each flexible main beam; all piezoelectric cantilever beams have the same orientation and are parallel to the axis direction; One end of all piezoelectric cantilever beams is pasted and fixed on the upper surface of the flexible main beam, the other end of the piezoelectric cantilever beam located on the most edge flexible main beam is suspended on the outside of the most edge flexible main beam, and the rest of the piezoelectric cantilever beams are The other ends are suspended on the adjacent rectangular holes; a plurality of piezoelectric cantilever beams on the same flexible main beam are arranged at equal intervals; a mass block is adhered to the suspended end of each piezoelectric cantilever beam. (figure 1).

The vibration pickup structure of the n×3 lattice vibration energy harvester includes a flexible frame main beam structure, a piezoelectric cantilever beam and a mass block. The main beam structure of the flexible frame adopts a high elastic molecular material with low Young's modulus, preferably polydimethylsiloxane (PDMS) in the present invention. The piezoelectric cantilever beam includes a substrate and a piezoelectric layer, wherein the piezoelectric layer is a piezoelectric ceramic film, which is bonded with one end of the substrate by conductive silver glue, and the mass block is adhered to the floating end of the substrate. The substrate is selected from a material with a small elastic modulus and high strength, which can withstand large deformation, and a copper sheet substrate is preferred in the present invention. The piezoelectric layer is made of piezoelectric material with strong piezoelectricity and high piezoelectric constant, and PZT is preferred in the present invention. The mass block is made of metal material with high density, low cost and easy processing, and iron block is preferred in the present invention.

The working principle of the present invention is as follows: both ends of the main beam structure of the flexible frame are fixed (both ends along the axis direction are fixed). When the present invention is placed in an actual environmental vibration system, under the excitation of the outside world, the main beam structure of the flexible frame is The fixed end vibrates and drives the entire main beam structure of the flexible frame to vibrate, so that the piezoelectric cantilever beam pasted on the surface of the main beam structure of the flexible frame vibrates together, and the piezoelectric cantilever beam transforms the mechanical vibration energy into electrical energy by deforming in the vibration. Through the design of n rows of flexible main beams, the size of the piezoelectric cantilever beam and the mass block on each row of flexible main beams is adjusted to change the effective mass of the flexible main beams, to realize the separation of vibration modes between different flexible main beams, and to widen the low frequency frequency band. Effect. All piezoelectric cantilevers are connected in series.

Compared with the prior art, the present invention has the following beneficial effects:

A flexible frame structure is used as the main beam. Flexible materials have small Young's modulus and high structural elasticity. The flexible frame structure is easier to feel the vibration of the external environment, and the vibration energy is transmitted to the piezoelectric cantilever beam, thereby reducing the vibration mode of each row of piezoelectric cantilever beams, and can realize broadband vibration energy in the low frequency range below 50 Hz collection.

Adopt n×3 lattice piezoelectric cantilever beam structure. By adjusting the size of the piezoelectric cantilever beam and the mass block on each row of flexible main beams, the effective mass of different flexible main beams is changed, the vibration mode separation between different flexible main beams is realized, and the effect of broadening the low frequency frequency band is achieved.

With the increase of the number of rows n in the n×3 lattice piezoelectric cantilever beam structure, the vibration mode of the energy harvester increases, and the available effective frequency band is broadened. As the number of rows n increases, the number of piezoelectric cantilevers in the energy harvester increases, the output voltage increases, and the output power of the system increases.

By increasing or decreasing the row number n of the piezoelectric cantilever beam, and changing the size of the piezoelectric cantilever beam and the mass block at the same time, the effective frequency bandwidth of the system can be adjusted in time, the continuity and stability of the output of the energy harvester can be improved, and the vibration energy can be enhanced. The environmental adaptability of the collector.

Description of drawings

Figure 1 is a schematic diagram of the overall structure of the present invention (a- flexible frame main beam structure, b- piezoelectric cantilever beam, c-mass block).

Figure 2 is a schematic structural diagram of a piezoelectric cantilever (c-mass, d-substrate, e-piezoelectric layer).

FIG. 3 is an output frequency response characteristic curve of the 2×3 lattice vibration pickup structure invented in Embodiment 1. FIG.

FIG. 4 is an output frequency response characteristic curve of the 3×3 lattice vibration pickup structure invented in the second embodiment.

FIG. 5 is an output frequency response characteristic curve of the 5×3 lattice vibration pickup structure invented in Embodiment 3. FIG.

Detailed ways

The present invention will be further clearly and completely described below with reference to specific embodiments.

Example 1

The present invention includes a flexible frame main beam structure a, a piezoelectric cantilever beam b and a mass c. The flexible frame main beam structure a is a rectangular frame-like structure with a hollow rectangular hole in the center; one end of the piezoelectric cantilever beam b is pasted and fixed On the upper surface of the main beam structure a of the flexible frame, the other end is suspended, the suspended length of the piezoelectric cantilever beam b is less than the width of the rectangular hole, and the mass c is attached to the suspended end of the piezoelectric cantilever beam b; six piezoelectric cantilever beams b (n=2) are arranged at equal intervals along the same direction on both sides of the rectangular hole.

The main beam structure a of the flexible frame is made of PDMS material, and the outer sides of the two sides of the frame parallel to the piezoelectric cantilever beam b are fixed.

The piezoelectric cantilever beam b includes a substrate d and a piezoelectric layer e. The piezoelectric layer e is pasted on the rear surface of the substrate d with conductive silver glue, and the mass c is pasted on the front end of the substrate d with AB glue. Among them: the substrate d is made of copper sheet material, and the piezoelectric layer e is made of PZT-5H material. As shown in Figure 3, the width of the substrate d is equal to the width of the piezoelectric layer e, but the length of the substrate d is greater than the length of the piezoelectric layer e. The conductive silver glue is pasted and fixed. The size of the six piezoelectric cantilever beams shown in this example is exactly the same as that of the mass block. They are distributed in two rows to the right on both sides of the rectangular hole, and are arranged in parallel at equal intervals along the long side of the hollow rectangle; One side of the 3 substrates d is aligned with the left end of the main beam structure a of the flexible frame, and the side of the three substrates d in the second row is aligned with the long side of the right side of the hollow rectangle on the main beam structure a of the flexible frame, and then use AB glue The substrate d of the piezoelectric cantilever beam b is pasted and fixed on the upper surface of the main beam structure a of the flexible frame, and the other end is suspended; the connection mode of the six piezoelectric cantilever beams b is series connection.

The mass c is made of iron. The mass block c is pasted and fixed on the front end of the substrate d with AB glue, aligned with the front end of the substrate d, and not in contact with the piezoelectric layer e; the mass block c has the same width as the piezoelectric cantilever beam b. The frequency response characteristic curve of its output is shown in Fig. 3.

Example 2

The invention includes a flexible frame main beam structure a, a piezoelectric cantilever beam b and a mass block c. The flexible frame main beam structure a is a rectangular frame-like structure, and the rectangular structure is provided with two hollow rectangular holes; One end is pasted and fixed on the upper surface of the main beam structure a of the flexible frame, the other end is suspended, the suspended length of the piezoelectric cantilever beam b is less than the width of the rectangular hole, and the mass c is adhered to the suspended end of the piezoelectric cantilever beam b; The electric cantilever beams b (n=3) are arranged at equal intervals along the same direction on both sides of the two rectangular holes.

The main beam structure a of the flexible frame is made of PDMS material, and the outer sides of the two sides of the frame parallel to the piezoelectric cantilever beam b are fixed.

The piezoelectric cantilever beam b includes a substrate d and a piezoelectric layer e. The piezoelectric layer e is pasted on the rear end surface of the substrate d with conductive silver glue, and the mass c is pasted on the front end surface of the substrate d with AB glue. Among them: the substrate d is made of copper sheet material, and the piezoelectric layer e is made of PZT-5H material. The width of the substrate d is equal to the width of the piezoelectric layer e attached to it, but the length of the substrate d is greater than the length of the piezoelectric layer e. Paste fixed. The dimensions of the nine piezoelectric cantilever beams and the size of the mass block in this embodiment are not exactly the same (the size of the piezoelectric cantilever beam b in the first row and the third row and the size of the mass block are exactly the same, and they are different from the size of the second row), They are distributed in three rows along the same direction on both sides of the two hollow rectangular holes, and are arranged in parallel at equal intervals along the longitudinal direction of the hollow rectangle; the three substrates d side of the first row and the left end of the flexible frame main beam structure a Aligned, one side of the 3 substrates d in the second row and the 3 substrates d in the third row are aligned with the right long sides of the two hollow rectangles on the main beam structure of the flexible frame The substrate d of the electric cantilever beam b is pasted and fixed on the upper surface of the main beam structure a of the flexible frame, and the other end is suspended; the connection mode of the nine piezoelectric cantilever beams b is series connection.

The mass c is made of iron. The mass block c is pasted and fixed on the front end of the substrate d with AB glue, which is aligned with the front end of the substrate d and does not contact the piezoelectric layer e; the width of the mass block c is the same as the width of the piezoelectric cantilever beam b attached to it. The frequency response characteristic curve of its output is shown in Fig. 4.

Example 3

The present invention includes a flexible frame main beam structure a, a piezoelectric cantilever beam b and a mass block c, the flexible frame main beam structure a is a rectangular frame-like structure, and the rectangular structure is provided with four hollow rectangular holes; One end is pasted and fixed on the upper surface of the main beam structure a of the flexible frame, the other end is suspended, the suspended length of the piezoelectric cantilever beam b is less than the width of the rectangular hole, and the mass c is adhered to the suspended end of the piezoelectric cantilever beam b; fifteen Piezoelectric cantilever beams b (n=5) are arranged at equal intervals along the same direction on both sides of the four rectangular holes.

The main beam structure a of the flexible frame is made of PDMS material, and the outer sides of the two sides of the frame parallel to the piezoelectric cantilever beam b are fixed.

The piezoelectric cantilever beam b includes a substrate d and a piezoelectric layer e. The piezoelectric layer e is pasted on the rear end surface of the substrate d with conductive silver glue, and the mass c is pasted on the front end surface of the substrate d with AB glue. Among them: the substrate d is made of copper sheet material, and the piezoelectric layer e is made of PZT-5H material. The width of the substrate d is equal to the width of the piezoelectric layer e attached to it, but the length of the substrate d is greater than the length of the piezoelectric layer e. Paste fixed. The dimensions of the fifteen piezoelectric cantilever beams and the mass blocks in this embodiment are not exactly the same (wherein the dimensions of the piezoelectric cantilever beams in different rows and the dimensions of the mass blocks are not exactly the same, and the dimensions of the three piezoelectric cantilever beams in each row are not exactly the same. The same size as the mass block), distributed in five rows to the right on both sides of the four hollow rectangular holes, and arranged in parallel at equal intervals along the long side of the hollow rectangle; the three substrates d side of the first row are connected to the flexible frame The left ends of the main beam structure a are aligned, and the sides of the three substrates d in each of the remaining rows (the 2nd, 3rd, 4th and 5th rows) are respectively aligned with the right long sides of the four hollow rectangles on the main beam structure a of the flexible frame. , and then use AB glue to stick and fix the substrate d of the piezoelectric cantilever beam b on the upper surface of the main beam structure a of the flexible frame, and the other end is suspended; the connection mode of the fifteen piezoelectric cantilever beams b is series connection.

The mass c is made of iron. The mass block c is pasted and fixed on the front end of the substrate d with AB glue, which is aligned with the front end of the substrate d and does not contact the piezoelectric layer e; the width of the mass block c is the same as the width of the piezoelectric cantilever beam b attached to it. The frequency response characteristic curve of its output is shown in Fig. 5.

Claims (4)

1. a bandwidth adjustable n×3 lattice vibration energy harvester based on modal separation technology, is characterized in that, comprises flexible frame main beam structure, piezoelectric cantilever beam and mass block; The flexible frame main beam structure is rectangular , select a center line of the rectangle as the axis, and the rectangle has n-1 hollow rectangular holes of equal size and the same spacing in sequence along the axis direction, and the solid parts of all hollow rectangular holes along the axis direction are used as flexible main beams , a total of n rows of flexible main beams are formed, where n≥2; multiple piezoelectric cantilever beams of the same number are pasted and fixed on each flexible main beam; all piezoelectric cantilever beams have the same orientation and are parallel to the axis direction; all piezoelectric cantilevers One end of the cantilever beam is pasted and fixed on the upper surface of the flexible main beam, the other end of the piezoelectric cantilever beam located on the most edge flexible main beam is suspended outside the most edge flexible main beam, and the other ends of the remaining piezoelectric cantilever beams are Suspended above the adjacent rectangular holes; multiple piezoelectric cantilevers on the same flexible main beam are arranged at equal intervals; a mass is attached to the suspended end of each piezoelectric cantilever; by adjusting each row of flexible main beams The size of the piezoelectric cantilever beam and the mass block on the beam changes the effective mass of different flexible main beams, realizes the vibration mode separation between different flexible main beams, and then achieves the effect of broadening the low frequency frequency band; all piezoelectric cantilever beams are realized by a series structure. connect. 2. The bandwidth-adjustable n×3 lattice vibration energy harvester based on modal separation technology according to claim 1, wherein the axis is the long centerline of the main beam structure of the flexible frame; The short side is parallel to the axis; there are three piezoelectric cantilever beams fixed on each flexible main beam. 3. The bandwidth-adjustable n×3 lattice vibration energy harvester based on modal separation technology according to claim 1 or 2, wherein the piezoelectric cantilever beam comprises a substrate and a piezoelectric layer, and the piezoelectric layer uses a The conductive silver glue is pasted on the rear end surface of the substrate, and the mass block is pasted on the front end surface of the substrate with AB glue. 4. The bandwidth-adjustable n×3 lattice vibration energy harvester based on modal separation technology as claimed in claim 3, wherein the substrate adopts copper sheet material, and the piezoelectric layer adopts PZT-5H material; The width is equal to the width of the piezoelectric layer to which it is attached, and the length of the substrate is greater than that of the piezoelectric layer; the main beam structure of the flexible frame adopts PDMS material.