A piezoelectric energy harvesting device and method for subway tracks

Abstract

This invention discloses a piezoelectric energy harvesting device and method for subway tracks, relating to the field of energy harvesting technology. It includes a floating rubber pad, a piezoelectric energy harvesting mechanism, and an energy storage mechanism. The piezoelectric energy harvesting mechanism is disposed within a rubber support block, a lateral buffer pad, and a buffer plate, among other floating rubber pads. The floating rubber pad consists of two layers: an upper rubber pad adhered to the upper part of the piezoelectric energy harvesting mechanism; and a lower concave rubber pad in which the piezoelectric energy harvesting mechanism is placed and adhered. The piezoelectric energy harvesting mechanism includes a stacked piezoelectric energy harvester, composed of multiple copper foils and piezoelectric ceramic sheets stacked together, with both the upper and lower parts of the stacked piezoelectric energy harvester being copper foils. The energy storage mechanism is located in the gap below the floating rubber plate and is connected to the stacked piezoelectric energy harvester via a busbar circuit for storing energy.

Description

Technical Field

[0001] This invention relates to the field of energy harvesting technology, specifically to a piezoelectric energy harvesting device and method for subway tracks. Background Technology

[0002] With the development of the times, the global energy crisis has become increasingly prominent, and people are paying more and more attention to the development and utilization of new energy sources. At present, significant progress has been made in countries such as Japan, the United States, and Europe in utilizing piezoelectric vibration energy. For example, Japan's new piezoelectric luminous road signs have reached the level of self-powered operation; Israel has enabled approximately 100 to 400 kilowatts of electricity per kilometer of road surface by embedding a large number of piezoelectric crystals into the asphalt of ordinary roads.

[0003] As a populous country, my country faces a significant resource shortage, making the development and utilization of new energy sources an urgent priority. With the continuous increase in the total mileage and operating frequency of my country's subways, the scale of track vibration energy generated by their operation is becoming increasingly substantial. Simultaneously, as subways are electrically powered, their electricity consumption is also growing rapidly. Therefore, track vibration energy, as a potential renewable energy source, has enormous development potential.

[0004] The piezoelectric effect is a phenomenon where certain dielectric materials deform under the influence of an external force in a specific direction, resulting in internal polarization and the appearance of opposite charges on their two opposing surfaces. When the external force is removed, the material returns to its uncharged state. If the pressure is a high-frequency vibration, it generates a high-frequency current. Piezoelectric energy harvesters utilize the piezoelectric effect of piezoelectric materials to convert mechanical energy such as vibrations and noise from the environment into electrical energy. These harvesters can extract energy from the environment to power microelectronic components.

[0005] The discovery of the piezoelectric effect provided theoretical support for the harvesting of vibration energy, and the development of piezoelectric materials made this technology a practical possibility. With the continuous increase in the total mileage of subways in my country and the rising frequency of operation, the scale of track vibration energy generated by their operation is becoming increasingly large. Subway rubber floating slabs have been proven to effectively buffer high-frequency vibrations and impacts caused by train operation.

[0006] However, existing rubber floating plates can only achieve the function of vibration reduction and noise reduction, and do not pay attention to the recovery and utilization of track vibration energy caused by vehicles; at the same time, existing devices for collecting track piezoelectric energy have disadvantages such as unreasonable placement, low piezoelectric efficiency, and easy damage to piezoelectric energy harvesters. Summary of the Invention

[0007] To address the aforementioned problems, this invention combines a piezoelectric energy harvesting device with a subway rubber floating plate, proposing a new subway track vibration energy harvesting device with piezoelectric energy collection function. Based on the existing vibration reduction and noise reduction functions, it adds the function of track vibration energy harvesting and utilization, thereby achieving environmental protection and energy saving, and realizing energy reuse.

[0008] This invention proposes a piezoelectric energy harvesting device for subway tracks, comprising a rubber floating plate, a piezoelectric energy harvesting mechanism, and an energy storage mechanism, wherein:

[0009] The bottom of the rubber floating plate is fixedly connected to the concrete pad stone at the bottom of the track by rubber support blocks. One pair of side walls of the rubber floating plate are fixedly connected to the concrete side walls of the track by lateral buffer pads. Buffer pads are provided on the other pair of side walls of the rubber floating plate.

[0010] The plurality of said piezoelectric energy harvesting mechanisms are respectively disposed within the rubber support block, the lateral buffer pad, and the buffer plate, and each said piezoelectric energy harvesting mechanism includes:

[0011] A stacked piezoelectric energy harvester is composed of multiple copper foils and piezoelectric ceramic sheets stacked together, with both the top and bottom parts of the stacked piezoelectric energy harvester being copper foils;

[0012] An upper rubber pad is bonded to the upper part of the stacked piezoelectric energy harvester. The upper surface of the upper rubber pad is provided with a plurality of first and second vibration damping bosses with frustum-shaped structures, and the height of the first vibration damping boss is higher than the height of the second vibration damping boss.

[0013] The lower rubber pad is bonded to the lower part of the stacked piezoelectric energy harvester;

[0014] The energy storage mechanism is located in the gap below the rubber floating plate and is connected to the stacked piezoelectric energy harvester through a busbar circuit for storing energy.

[0015] Furthermore, the copper foil and the piezoelectric ceramic sheet are bonded together by hot pressing using epoxy resin, and the thickness of the epoxy resin adhesive layer between the copper foil and the piezoelectric ceramic sheet is 0.005-0.01 mm.

[0016] Both the upper and lower rubber pads are bonded to the stacked piezoelectric energy harvester using epoxy resin via hot pressing.

[0017] Furthermore, the multiple piezoelectric ceramic sheets within the stacked piezoelectric energy harvester are electrically connected in parallel, and the stacked structure composed of multiple copper foils and piezoelectric ceramic sheets within the stacked piezoelectric energy harvester adopts a mechanical structure in parallel and is connected to the energy storage mechanism through a bus circuit.

[0018] Furthermore, the energy storage mechanism is a battery.

[0019] Furthermore, the rubber support block is a cylinder with a diameter of 300-400mm and a thickness of 30mm, and is placed in the groove at the bottom of the floating plate and the groove in the concrete pad stone, arranged below the floating plate with a gap of 1m.

[0020] The lateral buffer pads are cuboids with a thickness of 20mm, and are placed between the concrete sidewalls of the floating slab track, arranged on both sides of the floating slab with a 1m gap.

[0021] The buffer pad is a cuboid, with dimensions consistent with the central aperture of the floating plate, and is positioned at the center of the floating plate.

[0022] Furthermore, the thickness of the upper rubber pad is 10mm;

[0023] The lower rubber pad is a U-shaped pad with a bottom wall thickness of 10mm and a side wall thickness of 10mm.

[0024] The thickness of the stacked piezoelectric energy harvester is 5 mm;

[0025] Furthermore, the upper rubber pad and the lower rubber pad are fixed together by adhesive bonding and nailing.

[0026] Furthermore, the thickness of the copper foil is 0.05 mm;

[0027] The thickness of the piezoelectric ceramic sheet is 0.15 mm.

[0028] Furthermore, the height of the first vibration damping boss is 5.0 mm;

[0029] The height of the second vibration damping boss is 2.5mm.

[0030] Furthermore, the first and second vibration damping bosses on the upper rubber pad are arranged in a row at intervals.

[0031] This invention provides a method for harvesting piezoelectric energy from subway tracks, comprising the following steps:

[0032] When the subway passes over the track, the vibration generated by the wheels contacting the track puts pressure on the rubber support blocks, lateral buffer pads, and buffer pads through the track support platform equipped with rubber floating plates.

[0033] The piezoelectric ceramic sheets in the stacked piezoelectric energy harvesters located inside the rubber support block, the lateral buffer pad, and the buffer plate undergo deformation and vibration.

[0034] According to the piezoelectric effect, when a piezoelectric ceramic sheet is subjected to pressure, it generates opposite charges, forming an electric current and producing electrical energy.

[0035] The electrical energy generated by the piezoelectric ceramic sheet is stored in the energy storage mechanism through the bus rectifier circuit.

[0036] Compared with the prior art, the piezoelectric energy harvesting device and method for subway tracks provided by the present invention have the following advantages:

[0037] This invention combines a stacked piezoelectric energy harvester with a subway rubber floating plate, placing it below, to the side and in the middle of the track slab for buffering. An energy storage mechanism is arranged in the holes below the track slab, which can not only effectively buffer the vibration and impact generated by the train passing through the track, but also effectively collect the energy generated by the vibration.

[0038] The energy recovery scheme for existing track rubber floating plates proposed in this invention eliminates the need to reinstall energy harvesters and find new locations; it also avoids direct contact between the energy harvesters and the track structure, thus preventing delays in service life; at the same time, the designed vibration damping platform can not only increase energy recovery efficiency but also reduce track vibration noise. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the installation of the subway track piezoelectric energy harvesting device provided by the present invention;

[0040] Figure 2 Appendix to this invention Figure 1 Top view;

[0041] Figure 3 This is a schematic diagram of the structure of the subway track piezoelectric energy harvesting device provided by the present invention;

[0042] Figure 4 Appendix to this invention Figure 1 A schematic diagram of the stacked piezoelectric energy harvester 8.

[0043] In the figure: 1. Rubber floating plate, 2. Energy storage mechanism, 3. Rubber support block, 4. Lateral buffer pad, 5. Buffer pad plate, 6. Concrete pad stone, 7. Concrete side wall, 8. Stacked piezoelectric energy harvester, 9. Copper foil, 10. Piezoelectric ceramic sheet, 11. Upper rubber pad, 12. Lower rubber pad, 13. First vibration damping boss, 14. Second vibration damping boss. Detailed Implementation

[0044] The following is in conjunction with the appendix Figures 1 to 4 The following describes specific embodiments of the present invention in further detail. These embodiments are merely for illustrating the technical solutions of the present invention more clearly and should not be construed as limiting the scope of protection of the present invention.

[0045] Example 1: As Figure 1-4As shown, the present invention proposes a piezoelectric energy harvesting device and method for subway tracks, specifically including: a stacked piezoelectric energy harvester 8 and an energy storage mechanism 2. The stacked piezoelectric energy harvester 8 is provided with an upper rubber pad 11 and a lower rubber pad 12 at its top and bottom, respectively. The stacked piezoelectric energy harvester 8 is composed of copper foil 9 and piezoelectric ceramic sheets 10 stacked together. The copper foil 9 and the piezoelectric ceramic sheets 10 are bonded together with epoxy resin by hot pressing. The upper and lower parts of the stacked piezoelectric energy harvester 8 are both copper foil 9. The upper surface of the upper rubber pad 11 has multiple vibration damping bosses, including a first vibration damping boss 13 and a second vibration damping boss 14. Both the first vibration damping boss 13 and the second vibration damping boss 14 are frustum-shaped structures. The height of the first vibration damping boss 13 is higher than the height of the second vibration damping boss 14.

[0046] The first vibration damping boss 13 and the second vibration damping boss 14 are both frustum-shaped, with the same base area and the same frustum inclination angle. Since the height of the first vibration damping boss 13 is higher than the height of the second vibration damping boss 14, the top area of ​​the first vibration damping boss 13 is smaller than the top area of ​​the second vibration damping boss 14.

[0047] The upper rubber pad is 10mm thick, the lower rubber pad is U-shaped, the bottom wall is 10mm thick, the side wall is 10mm thick, and the stacked piezoelectric energy harvester 8 is 5mm thick.

[0048] The copper foil 9 has a thickness of 0.05 mm, and the piezoelectric ceramic sheet 10 has a thickness of 0.15 mm.

[0049] In the stacked piezoelectric energy harvester 8, the electrical connections of each layer of ceramic sheets in the stacked structure are in parallel. The entire stacked structure is mechanically in parallel and is connected to the energy storage mechanism 2 through a bus circuit for energy storage.

[0050] The height of the first damping boss 13 is 5.0 mm, and the height of the second damping boss 14 is 2.5 mm.

[0051] The copper foil 9 and the piezoelectric ceramic sheet 10 are bonded together with epoxy resin by hot pressing.

[0052] The first vibration damping boss 13 and the second vibration damping boss 14 are arranged in rows at intervals.

[0053] Since the copper foil 9 and the piezoelectric ceramic sheet 10 in the stacked piezoelectric energy harvester 8 are relatively thin, the thickness of the epoxy resin adhesive layer between the copper foil 9 and the piezoelectric ceramic sheet 10 should be controlled within 0.005-0.01mm, and the final thickness of the stacked piezoelectric energy harvester 8 should be controlled within 5.0mm.

[0054] This invention, by setting up vibration-damping bosses of two different heights and a stacked piezoelectric energy harvester containing copper foil and piezoelectric ceramic sheets, further enables the rubber floating plate to collect and store track vibration energy on the basis of its existing vibration-damping and noise-reducing functions. This greatly improves energy utilization efficiency, develops track vibration energy as a new type of renewable energy, and alleviates my country's energy utilization pressure.

[0055] When the subway passes through the track, the vibration generated when the wheels come into contact with the track can cause the buffer pad 5 and the rubber support block 3 to be subjected to pressure through the rubber floating plate 1 and the rubber floating plate 1, thereby causing the piezoelectric ceramic sheet 10 in the stacked piezoelectric energy harvester 8 to deform. The rapid deformation then generates vibration, and the piezoelectric ceramic sheet 10 then converts the pressure it receives into electrical energy, thereby achieving the effect of power generation.

[0056] The piezoelectric ceramic sheet 10 can be made of a variety of materials; in this invention, the PZT-5H type piezoelectric ceramic sheet is used. Compared with other piezoelectric materials, this type of piezoelectric ceramic sheet has relatively high stiffness and strength after stacking. At the same time, the stacked structure generates more energy than a single piezoelectric sheet of the same thickness, which is in line with the purpose of this invention to improve energy utilization efficiency.

[0057] For the fabrication of the stacked piezoelectric energy harvester 8, since the solvent used for bonding the thin sheets has a certain degree of volatility, the shorter the time required for the hot-pressed thin sheets in the stacked piezoelectric energy harvester 8, the higher the proportion of solvent in the thin sheets, and the better the flexibility of the thin sheets. The thin sheets are also easier to bond together, and the stacking process will be smoother.

[0058] The following uses a subway line as an example to calculate and explain the piezoelectric energy conversion of this invention. This subway line adopts a rubber floating plate structure, with a length of 6m and a width of 3m; the rubber support block is cylindrical with a diameter of 310mm and a thickness of 30mm; each car has 4 wheelsets and is configured in 8-car formations, with an operating speed of 80km / h and a weight of 38 tons. Considering the properties of the piezoelectric material and the size of the rubber support block, a PZT piezoelectric ceramic sheet with a diameter of 30mm is selected. Assuming a circuit efficiency of 75%, the piezoelectric energy of a single piezoelectric ceramic sheet located within the rubber support block 3 is calculated as follows:

[0059] The formula for calculating charge is:

[0060] The formula for calculating the capacitance of a piezoelectric energy harvester is:

[0061] The current intensity flowing through the piezoelectric ceramic sheet 10 in the thickness direction is

[0062] The voltage caused by track vibration load is:

[0063] The electrical energy converted by the train wheelset in one pass is

[0064] In the formula: The pressure borne by the piezoelectric ceramic sheet; The thickness of the piezoelectric ceramic sheet; The surface area of ​​the piezoelectric ceramic sheet subjected to force; Loading frequency; The vacuum dielectric constant of piezoelectric materials , is the relative permittivity of the piezoelectric material, taken as 2859 here; piezoelectric coefficient .

[0065] The above formula yields the following result:

[0066] Current ;

[0067] Voltage ;

[0068] The electrical energy generated by the piezoelectric ceramic thin-film unit is: ;

[0069] Since each stacked piezoelectric energy harvester can approximately stack 25 PZT piezoelectric ceramic sheets of this size, and each rubber floating plate has two stacked piezoelectric energy harvesters, a 6m long floating plate can hold 12 rubber support blocks. Based on local subway daily operating data, assuming an average daily train flow of approximately 400 trips, each rubber floating plate, with the buffer support blocks 3, can generate approximately 1.548 × 10⁻⁶ energy. 7 J's electrical energy;

[0070] Similarly, for buffer pad 5, the electrical energy that can be generated is: 1.032 × 10⁻⁶. 6 J;

[0071] Similarly, for the lateral cushioning pad 4, the electrical energy that can be generated is: 5.467 × 10⁻⁶. 5 J;

[0072] Therefore, a single 6m long rubber floating board can generate 4.7kWh of electricity per day.

[0073] Based on the energy consumption calculation of a 5-square-meter subway LED advertising display screen, 300 LED beads can be arranged per square meter. The power of a single-color LED bead is 0.1W. With 10 hours of lighting per day, the daily energy consumption is about 1.5kWh. Therefore, the energy recovered by a single floating plate can power the subway LED advertising screen for 3.16 days.

[0074] Based on the calorific value of 2.93 × 10⁻⁶ kilograms of coal... 7 Based on an energy conversion efficiency of 40%, a single piezoelectric rubber floating plate can save 0.529 tons of coal and reduce carbon dioxide emissions by 1.933 tons annually. Therefore, this invention patent has significant economic and social benefits.

[0075] If the device is installed on the buffer pads 5 and rubber support blocks 3 within all the rubber floating plates 1 along the entire subway line, the energy generated by the stacked piezoelectric energy harvesters within the rubber floating plates 1 can effectively alleviate the subway's power consumption and contribute to the establishment of a low-carbon transportation system.

[0076] Regarding the selection of energy storage mechanisms, we recommend using large-capacity batteries to store the collected piezoelectric energy.

[0077] As can be seen, this invention addresses the problems of high energy consumption, large electricity demand, and high supply costs associated with subway operation. By researching a rubber floating plate based on piezoelectric track vibration energy utilization, it alleviates the significant electricity losses caused by traditional subway operations and the environmental pollution from conventional energy generation, greatly improving energy efficiency and providing a new solution to alleviate my country's energy shortage. Regarding the placement and application of piezoelectric energy harvesters, this invention combines the rubber support layer in the subway track slab with the piezoelectric energy harvester, eliminating the need for reinstallation and relocation of the harvester, and avoiding direct contact between the harvester and the track structure, thus extending its service life. Simultaneously, the designed vibration damping platform increases energy recovery efficiency and reduces track vibration noise.

[0078] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited thereto. Any simple changes or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. A metro track piezoelectric energy harvesting device, characterized in that, The utility model relates to a kind of subway track piezoelectric energy collection devices, including: Rubber floating slab (1), piezoelectric energy collection mechanism and energy storage mechanism (2), wherein: The bottom of the rubber floating slab (1) is fixedly connected with the concrete cushion (6) of track bottom by rubber support block (3), and the pair of side walls of the rubber floating slab (1) is fixedly connected with the concrete side wall (7) of track by lateral buffer rubber pad (4), and the other pair of side walls of the rubber floating slab (1) is equipped with buffer pad plate (5); A plurality of piezoelectric energy collection mechanisms are respectively arranged in rubber support block (3), lateral buffer rubber pad (4) and buffer pad plate (5), and each piezoelectric energy collection mechanism comprises: Stacked piezoelectric energy harvester (8) is stacked by a plurality of copper foil (9) and piezoelectric ceramic sheet (10), and the upper and lower parts of the stacked piezoelectric energy harvester (8) are copper foil (9); Upper rubber pad plate (11) is bonded to the upper part of the stacked piezoelectric energy harvester (8), the upper surface of the upper rubber pad plate (11) is provided with a plurality of first damping bosses (13) and second damping bosses (14) of circular truncated cone structure, and the height of the first damping boss (13) is higher than the height of the second damping boss (14); Lower rubber pad plate (12) is bonded to the lower part of the stacked piezoelectric energy harvester (8); The energy storage mechanism (2) is arranged at the lower space of the rubber floating slab (1), connected with the stacked piezoelectric energy harvester (8) through the current collection circuit, for storing energy; The rubber support block (3) is a cylinder, the diameter is 300-400mm, the thickness is 30mm, is placed in the floating slab (1) plate bottom groove and concrete cushion (6) groove, is arranged below the floating slab (1) according to 1m interval; The lateral buffer rubber pad (4) is a cuboid, the thickness is 20mm, is placed between the concrete side wall (7) of the floating slab (1) track, is arranged on both sides of the floating slab according to 1m interval; The buffer pad plate (5) is a cuboid, the size is consistent with the central aperture of the floating slab (1), and is arranged at the center of the floating slab (1); The thickness of the upper rubber pad plate (11) is 10mm; The lower rubber pad plate (12) is a concave-shaped pad plate, and the bottom wall thickness thereof is 10mm, and the side wall thickness is 10mm; The thickness of the stacked piezoelectric energy harvester (8) is 5mm; And the upper rubber pad plate (11) and the lower rubber pad plate (12) are fixed by cementing and nailing.

2. The subway track piezoelectric energy collection device according to claim 1, wherein: The copper foil (9) and the piezoelectric ceramic sheet (10) are bonded by hot pressing method, and the thickness of the epoxy resin bonding layer between the copper foil (9) and the piezoelectric ceramic sheet (10) is 0.005-0.01mm; The upper rubber pad plate (11) and the lower rubber pad plate (12) are bonded with the stacked piezoelectric energy harvester (8) by hot pressing method, using epoxy resin.

3. The subway track piezoelectric energy collection device according to claim 1, wherein: The multiple piezoelectric ceramic sheets (10) in the stacked piezoelectric energy harvester (8) are connected in parallel, the multiple copper foils (9) and piezoelectric ceramic sheets (10) in the stacked piezoelectric energy harvester (8) form a parallel mechanical structure, and the copper foils (9) and piezoelectric ceramic sheets (10) are connected to the energy storage mechanism (2) through a bus circuit.

4. The piezoelectric energy harvesting device for subway track according to claim 1, characterized in that: The energy storage mechanism (2) is a battery.

5. The piezoelectric energy harvesting device for subway track according to claim 1, characterized in that: The thickness of the copper foil (9) is 0.05 mm; The thickness of the piezoelectric ceramic sheet (10) is 0.15 mm.

6. The piezoelectric energy harvesting device for subway track according to claim 1, characterized in that: The height of the first damping boss (13) is 5.0 mm; The height of the second damping boss (14) is 2.5 mm.

7. The piezoelectric energy harvesting device for subway track according to claim 1, characterized in that: The first damping boss (13) and the second damping boss (14) on the upper rubber pad (11) are arranged in columns and intervals.

8. A subway track piezoelectric energy harvesting method based on the subway track piezoelectric energy harvesting device according to any one of claims 1-7, characterized in that, The method comprises the following steps: When the subway passes through the track, the vibration generated by the contact between the wheel and the track is transmitted to the rubber support block (3), the lateral buffer rubber pad (4) and the buffer pad (5) through the rail support platform with the rubber floating pad (1); The piezoelectric ceramic sheet (10) in the stacked piezoelectric energy harvester (8) in the rubber support block (3), the lateral buffer rubber pad (4) and the buffer pad (5) deforms and vibrates; According to the piezoelectric effect, the piezoelectric ceramic sheet (10) generates positive and negative charges after being subjected to pressure, forming an electric current and generating electric energy; The electric energy generated by the piezoelectric ceramic sheet (10) is stored in the energy storage mechanism (2) through the bus circuit.

Images