Energy capture and state self-sensing device, structural design method and system

Abstract

The application provides an energy capturing and state self-sensing device, a structural design method and a system. The energy capturing and state self-sensing device is arranged in a floating slab track spring sleeve and is connected in series with a spring. Through collection and conversion of mechanical energy of spring vibration, self-power supply of the system is realized. Meanwhile, the high piezoelectric sensitivity of the piezoelectric ceramic is used to sense the mechanical state of the spring, thereby providing technical support for long-term online monitoring and intelligent operation and maintenance of key parts of the floating slab track.

Description

Technical Field

[0001] This application relates to the field of rail transit technology, and in particular to an energy harvesting and state self-sensing device, structural design method and system. Background Technology

[0002] With the rapid development of urban rail transit and railway systems, the issues of vibration, noise, and long-term operational status monitoring in the service environment of track structures have received increasing attention. Floating slab tracks, due to their excellent vibration reduction and noise reduction performance, have been widely used in urban rail transit sections with high requirements for environmental vibration control. This type of track structure typically uses elastic elements such as steel springs and rubber pads to achieve vibration isolation between the track superstructure and the foundation. Among these, the steel spring sleeve, as a key stress-bearing and vibration-isolation component of the floating slab track, continuously bears complex vibration loads under repeated dynamic loads from trains. Its stress state and service performance directly affect the vibration reduction effect and operational safety of the floating slab track.

[0003] In existing floating slab track systems, steel springs primarily serve as supports, dampers, and buffers. During operation, they undergo continuous compressive deformation and vibration response, containing usable mechanical energy. However, current technologies largely focus on the vibration isolation performance of steel springs, the dynamic response of track structures, and service life assessment, with less attention paid to the effective recovery and utilization of the mechanical energy generated by steel spring vibrations. An integrated device that balances structural adaptability, energy capture efficiency, and long-term stability has not yet been developed. Furthermore, existing track condition monitoring systems typically rely on external power supplies, periodic battery replacements, or centralized wiring for power, which not only increases installation and maintenance costs but also, to some extent, restricts the long-term, stable, and large-scale application of monitoring systems in complex track environments.

[0004] On the other hand, the requirements for real-time and intelligent condition monitoring of rail infrastructure are constantly increasing. Especially during the service of floating slab tracks, the stress state of steel springs, vibration levels, and related structural response parameters are of great significance for assessing track operating status, providing early warning of abnormal conditions, and guiding maintenance decisions. Existing monitoring methods typically use independent sensors to detect target parameters, but they generally suffer from problems such as large additional structural space requirements, strong power supply dependence, separation of sensing and power supply functions, and low system integration. These issues make it difficult to meet the application requirements of miniaturization, self-powering, and long-term online monitoring under the complex operating conditions of floating slab tracks. Summary of the Invention

[0005] This application proposes an energy harvesting and state self-sensing device, structural design method and system, which can solve one of the problems existing in the background art.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] In a first aspect, an energy harvesting and state self-sensing device is provided, which is applied to a track system. The track system includes: a box girder, a floating plate that is floated on the box girder by a spring, and a track assembled on the floating plate. The floating plate is provided with a sleeve for accommodating the spring, and the energy harvesting and state self-sensing device is disposed on one side of the track.

[0008] The energy harvesting and state sensing device includes: an upper cover plate, a lower cover plate, a central pressure-bearing block, several radial sliding blocks, and several piezoelectric ceramic stacks. The upper cover plate, the central pressure-bearing block, and the lower cover plate are axially movable and assembled by pre-tightening bolts. The upper cover plate is located on one side of the track, the lower cover plate is located on one side of the box girder, the central pressure-bearing block is located between the upper cover plate and the lower cover plate, the radial sliding blocks are distributed around the central pressure-bearing block and abut against the central pressure-bearing block, and a first wedge-shaped abutment part is provided on one side of the radial sliding block located on the central pressure-bearing block. The central pressure block is provided with a second wedge-shaped abutment on one side of the radial sliding block, which cooperates with the first wedge-shaped abutment. Each piezoelectric ceramic stack is disposed between the radial sliding block and the inner wall of the lower cover plate. When a train passes over the track, the spring is compressed and deformed, and the central pressure block of the energy capture and state self-sensing device moves axially, so that the radial sliding block, due to the abutment between itself and the central pressure block, exerts a pressing effect on the piezoelectric ceramic stack. The piezoelectric ceramic stack generates electrical energy or a state sensing electrical signal due to the pressing effect.

[0009] In one possible design of the first aspect, the matching resistance of the energy trapping and state-sensing device is obtained in the following manner:

[0010] By using experience and the resistance-current-voltage-power formula, the range of values ​​for the matching resistor is determined.

[0011] Then, values ​​are taken within the specified range and calculated according to the formula;

[0012] Furthermore, the maximum value is found through cubic spline interpolation and used as the resistance value of the matching resistor.

[0013] In one possible design of the first aspect, the resistance value of the matching resistor is 5.5kΩ.

[0014] In one possible design of the first aspect, the energy harvesting and state sensing device comprises: a PZT-5H piezoelectric ceramic stack for generating electrical energy, and a porous piezoelectric ceramic stack for generating state-sensing electrical signals.

[0015] In one possible design of the first aspect, the porous piezoelectric ceramic is prepared by a water-based synchronous DIW-freeze-casting method, and its piezoelectric voltage sensitivity is 4.5V / kPa.

[0016] In one possible design of the first aspect, the piezoelectric ceramic stack is composed of a plurality of piezoelectric ceramic sheets stacked together, with adjacent piezoelectric ceramic sheets having opposite polarization directions.

[0017] Secondly, a structural design method is provided for the energy harvesting and state self-sensing device as described in any possible design of the first aspect above, wherein the dimensions of the energy harvesting and state self-sensing device are obtained in the following manner:

[0018] Where f(x) is a nonlinear programming function, Let α be a nonlinear inequality constraint function, where α is the angle between the wedge-shaped surface of the wedge-shaped contact part and the horizontal plane. is the force transmission coefficient; μ is the friction coefficient; f is the design value of the device material strength; A is the area of ​​the cross-section of the central bearing block corresponding to the center of the contact surface between the central bearing block and the radial sliding block; F is the external load; parameter vector x=[ ] = [α, N, a, b, h], where N is the number of piezoelectric sheets, a, b, and h are the length, width, and thickness of the piezoelectric ceramic sheets, respectively; lb and ub are the threshold values.

[0019] In one possible design approach of the second aspect, the obtained parameter vector is x=[85°,60,40mm,40mm,1mm].

[0020] Thirdly, a system is provided comprising the energy harvesting and state sensing device described in any of the possible design embodiments of the first aspect above, the system further comprising:

[0021] The data acquisition module is used to acquire the state sensing electrical signal from the energy capture and state self-sensing device, and to analyze, identify and store the data corresponding to the state sensing electrical signal to determine the force change and vibration state of the spring.

[0022] In addition, there is a communication module used to upload the force changes and vibration status of the spring to the cloud platform.

[0023] In one possible design of the third aspect, the energy harvesting and state self-sensing device further includes a power supply module, which includes a self-powered interface, a voltage regulator chip, a solar panel, and a lithium iron phosphate battery. The energy harvesting and state self-sensing device, the self-powered interface, the voltage regulator chip, and the lithium iron phosphate battery are connected in sequence, and the solar panel is connected to the lithium iron phosphate battery.

[0024] Beneficial effects:

[0025] Based on the above technical solution, the energy harvesting and state self-sensing device is arranged in the spring sleeve of the floating slab track and connected in series with the spring. By collecting and converting the mechanical energy of the spring vibration, the system can achieve self-powering. At the same time, the high voltage sensitivity of the piezoelectric ceramic is used to sense the mechanical state of the spring, providing technical support for long-term online monitoring and intelligent operation and maintenance of key parts of the floating slab track. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of an energy harvesting and state self-sensing system based on porous piezoelectric ceramics, provided as an embodiment of this application.

[0028] Figure 2 This is a schematic diagram showing the arrangement of the energy harvesting and state sensing device provided in the embodiments of this application in the floating plate track structure.

[0029] Figure 3 This is a schematic diagram of the energy harvesting and state self-sensing device provided in an embodiment of this application.

[0030] Figure 4 This is a schematic diagram of the piezoelectric ceramic stack circuit connection provided in an embodiment of this application.

[0031] Figure 5 This is a structural design diagram of the self-powered interface provided in an embodiment of this application.

[0032] Figure 6 The circuit structure diagram of the AP64500 chip provided in the embodiments of this application is shown.

[0033] Figure 7 A schematic diagram of the force on the central pressure block of the energy harvesting and state self-sensing device provided in the embodiments of this application.

[0034] Figure 8 A schematic diagram of the forces acting on the radial sliding block of the energy harvesting and state sensing device provided in this application embodiment.

[0035] Figure 9 A physical diagram of the energy harvesting and state self-sensing device provided in the embodiments of this application.

[0036] Figure 10 The output power time history diagram of the energy harvesting and state self-sensing device provided in the embodiments of this application.

[0037] Figure 11 A graph showing the relationship between the output electrical energy and circuit resistance of the energy harvesting and state sensing device provided in this application embodiment.

[0038] Reference numerals: 21. Sound barrier; 22. Steel spring vibration isolator; 23. Track; 24. Steel spring; 25. Box girder; 26. Pad plate; 27. Energy capture and state self-sensing device; 28. Concrete floating plate; 1. Pre-tightening bolt; 2. Upper cover plate; 3. Central bearing block; 4. Radial sliding block; 5. Piezoelectric ceramic stack; 6. Lower cover plate; 41. Electrode layer; 42. PZT-5H piezoelectric ceramic stack; 411. First wedge-shaped abutment part; 412. Second wedge-shaped abutment part. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0040] It should be noted that although functional modules are divided in the device schematic diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the device or the order in the flowchart. The terms "first," "second," etc., in the specification and the above-mentioned figures are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0042] This embodiment proposes an energy harvesting and state self-sensing device based on porous piezoelectric ceramics. The system can realize energy harvesting, energy storage and supply, state sensing and remote monitoring. It has the advantages of compact structure, high integration, strong self-powering capability and long-term online monitoring.

[0043] To achieve the above technical objectives, this embodiment adopts the following technical solution:

[0044] like Figure 1 and Figure 3 As shown, an energy harvesting and state sensing device based on porous piezoelectric ceramics includes:

[0045] There are 5 piezoelectric ceramic stacks, a total of six groups, five of which are commercial PZT-5H piezoelectric ceramic stacks, and the other group is a porous piezoelectric ceramic stack;

[0046] An energy harvesting and state sensing device is placed in a floating plate steel spring sleeve and connected in series with the steel spring, enabling it to directly withstand external loads. Its structure includes an upper cover plate 2, a lower cover plate 6, a central pressure block 3, and radial sliding blocks 4. A central pressure block 3 is located at the center between the upper cover plate 2 and the lower cover plate 6. Six sets of radially distributed sliding blocks 4 are symmetrically arranged around the central pressure block 3. The central pressure block 3 and the radial sliding blocks 4 cooperate to convert and amplify the vertical pressure on the upper cover plate 2 into a radial horizontal force, which acts on the piezoelectric ceramic stack 5, realizing the conversion of mechanical energy into electrical energy.

[0047] The upper cover plate 2, the central bearing block 3, and the lower cover plate 6 are axially movable and assembled by pre-tightening bolts 1;

[0048] The radial sliding block 4 is provided with a first wedge-shaped abutment part 411 on one side of the central pressure block 3, and the central pressure block 3 is provided with a second wedge-shaped abutment part 412 on one side of the radial sliding block 4 that cooperates with the first wedge-shaped abutment part. Each piezoelectric ceramic stack 5 is located between the radial sliding block 4 and the inner wall of the lower cover plate 6. When a train passes by on the track, the spring is compressed and deformed, and the central pressure block 3 of the energy capture and state self-sensing device moves axially, so that the radial sliding block 4 presses against the piezoelectric ceramic stack 5 due to the abutment action between it and the central pressure block 3. The piezoelectric ceramic stack 5 generates electrical energy or state sensing electrical signal due to the pressing action.

[0049] The power supply module consists of a self-powered interface, a voltage regulator chip, a solar panel, and a lithium iron phosphate battery, which can continuously supply power to the data acquisition module and the communication module.

[0050] The data acquisition module collects and transmits data to the microcontroller through a low-power digital power monitoring chip;

[0051] The communication module connects to the cloud platform via 4G / 5G through a LoRa / NB-IoT dual-mode chip, and connects to the software terminal and mobile phone.

[0052] like Figure 2As shown, the energy harvesting and state self-sensing device is applied to the track system, which includes: a box girder 25, a concrete floating plate 28 suspended on the box girder by steel springs, and a track assembled on the concrete floating plate. The concrete floating plate is provided with a sleeve for accommodating the steel springs, and the energy harvesting and state self-sensing device is located on one side of the track. Figure 2 The system also includes a sound barrier 21 located on the side of track 23, a pad 26 in the sleeve, a steel spring isolator 22 consisting of steel springs 24, and an energy harvesting and state self-sensing device (PE-VEH) 27.

[0053] Furthermore, such as Figure 4 As shown, the piezoelectric ceramic stack is composed of 60 piezoelectric ceramic sheets stacked together, with adjacent piezoelectric ceramic sheets having opposite polarization directions. Five sets of commercial PZT-5H piezoelectric ceramic stacks 42 are connected to the power supply module after rectification and voltage regulation; the porous piezoelectric ceramic stack is connected to the data acquisition module after signal conditioning. The electrode sheets involved in the electrode layer 41 are all made of copper, and the electrode sheets are the same size as the piezoelectric ceramic sheets, forming a full-coverage arrangement.

[0054] Furthermore, the energy harvesting and state self-sensing device is equipped with a force amplification mechanism. This force amplification mechanism consists of a central pressure-bearing block disposed between the upper and lower cover plates, a radial sliding block symmetrical about the central pressure-bearing block, and a piezoelectric ceramic stack. The wedge-shaped contact is formed between the inclined wedge surface of the central pressure-bearing block and the inclined section of the radial sliding block, serving as a path for force transmission, amplification, and conversion. At the same time, the bottom of the radial sliding block is engaged in a groove on the upper surface of the lower cover plate, allowing it to maintain radial movement.

[0055] Furthermore, the power supply module includes:

[0056] Self-powered interface: Composed of a full-bridge rectifier, a self-powered switch, and a buck converter, it converts the collected alternating current energy into direct current energy; voltage regulator chip: such as... Figure 6 As shown, the AP64500 chip is used to step down and regulate the power output from the self-powered interface and output it to the energy storage unit; the solar panel; and the lithium iron phosphate battery: powering the data acquisition module and the communication module.

[0057] like Figure 5 As shown, the self-powered interface consists of a full-bridge rectifier, a self-powered switch, and capacitors and inductors. Its working principle is as follows: the alternating electrical energy generated by the piezoelectric stack is converted into direct current by the full-bridge rectifier. However, at this point, the harmonics are relatively large, so the self-powered interface and the buck converter (composed of inductors and capacitors) further reduce the voltage and stabilize the current. The working principle of the self-powered switch is as follows: Figure 5As shown, the peak detection switch (equivalent to a self-powered switch) consists of three parts: a peak detector, a comparator, and a synchronous switch. The peak detector is composed of diode D1 and capacitor C1, utilizing the unidirectional conductivity of the diode and the charging and discharging characteristics of the capacitor to maintain the peak value of the input voltage. The comparator is composed of PNP transistor Q1 and diode D3, utilizing the base-emitter conduction characteristic of the transistor to form the trigger condition. The synchronous switch is composed of an NPN transistor Q2 and diode D2. When the voltage difference between the base and emitter of Q2 is greater than the conduction threshold, the transistor conducts, i.e., the switch closes. The specific working process of the peak detection switch is as follows: When the input voltage V... P When the voltage begins to rise, diode D1 is forward-biased, and electrical energy begins to transfer to capacitor C1. The voltage across capacitor C1 continuously increases. At this time, the synchronous switch branch is still in the off state, and the overall circuit behaves as "open." When V P When the peak value is reached, the voltage across capacitor C1 is V. P -V D V then P The voltage begins to decrease, but due to the unidirectional conduction characteristic of the diode, the voltage across capacitor C1 remains constant. At this time, the emitter of transistor Q1 is connected to capacitor C1, and its potential is provided by C1; while the base of transistor Q1 is connected to the input terminal, and its potential changes with V. P The voltage V across C1 decreases. C1 With V P The difference is greater than the conduction threshold V between the emitter and base of Q1. BE When the transistor Q1 is turned on, transistor Q2 is turned on in the same way, and energy begins to transfer to the output terminal after the transistor is turned on.

[0058] Furthermore, the data acquisition module includes:

[0059] Low-power digital power monitoring chip: Microchip PAC1811 chip; Microcontroller: STM32L476RG.

[0060] Furthermore, the communication module includes:

[0061] LoRa / NB-IoT dual-mode chip; Cloud platform: Alibaba Cloud IoT platform.

[0062] Furthermore, the porous piezoelectric ceramic is prepared by a water-based synchronous DIW-freeze casting method, and its piezoelectric voltage sensitivity is 4.5V / kPa. Under the same load, its open-circuit voltage sensitivity is about 50% higher than that of dense PZT stacks.

[0063] Furthermore, the energy harvesting and state sensing device is equipped with preload bolts and nuts connecting the upper and lower cover plates, which can provide vertical preload force to the device. Simultaneously, the preload bolts pass through the central bearing block, and the central hole diameter of the central bearing block is slightly larger than the diameter of the preload bolts.

[0064] Furthermore, in the energy harvesting and state sensing device, the piezoelectric ceramic stack is fixedly connected to the radial sliding block and the lower cover plate enclosure respectively by epoxy resin adhesive; the guide contact surface between the radial sliding block and the groove of the lower cover plate, and the contact surface between the inclined section of the radial sliding block and the inclined wedge surface of the central bearing block are all provided with a lubricating layer, which is a lithium molybdenum disulfide grease.

[0065] The following analysis uses a specific example, taking a steel spring floating track in urban rail transit as an example. Before this embodiment can officially begin operation, two preliminary preparatory tasks still need to be completed.

[0066] Preliminary preparation work 1: Optimization of device size parameters in this case:

[0067] like Figure 7 , Figure 8 As shown, when the train passes through the steel spring floating slab track at a constant speed of 120 km / h, the force at the steel spring fulcrum caused by the train's vibration is converted and amplified into a horizontal force by a force amplification mechanism composed of a central bearing block and radial sliding blocks, and then transmitted to the six sets of piezoelectric ceramic stacks. When the upper cover plate is subjected to an external load F, let F1 be F / 6, the coefficient of friction between the iron blocks be μ (after lubrication), and the angle between the wedge-shaped surface and the horizontal plane be α (α < 90°). f1 and f2 are the frictional forces between the wedge-shaped surface of the central bearing block and the inclined surfaces of the two radial sliding blocks at symmetrical positions, and their magnitudes are equal. N1 and N2 are the pressures between the central bearing block and the two radial sliding blocks at symmetrical positions, and their magnitudes are also equal. N3 is the supporting force provided by the lower cover plate to the radial sliding blocks. H represents the frictional force between the lower cover plate and the radial sliding block, and H and P represent the horizontal thrust and reaction force of the radial sliding block on the piezoelectric stack, respectively. The force transmission coefficient can be obtained from the force diagram of the central bearing block:

[0068] Vertical direction: (1)

[0069] Since the apparatus is centrally symmetric, i.e., f1=f2, N1=N2, f1=μN1, we get: (2)

[0070] From the overall method, we know that N3 = F1. According to the force diagram of the radial sliding block, we can obtain:

[0071] Horizontal direction: (3) (4)

[0072] By combining equations (2) and (4), we can obtain: (5) (6)

[0073] For the strength requirements of the device, under the maximum load, the strength of the device should meet the requirements of formula (7), where f is the design value of the device material strength and A is the area of ​​the cross section of the central bearing block corresponding to the center of the contact surface between the central bearing block and the radial sliding block. (7)

[0074] The peak output power of a piezoelectric ceramic stack under the action of a force with frequency ω and amplitude H is... for: (8)

[0075] Substituting into the above formula, we get: (9)

[0076] That is, the peak output power is proportional to the square of the equivalent capacitance divided by the effective piezoelectric constant, where the effective capacitance is... Effective piezoelectric constant λ and δ are empirical coefficients, which are taken as 1 when piezoelectric ceramic sheets are connected in parallel. Where is the dielectric constant. denoted as the piezoelectric strain constant, h as the thickness of the piezoelectric ceramic sheet, a and b as the length and width of the piezoelectric ceramic sheet, respectively, and N as the total number of piezoelectric ceramic sheet layers in the piezoelectric ceramic stack.

[0077] Subsequently, the parameters of the device size were optimized. Under the constraints of structural strength and device size, a nonlinear programming problem was constructed with the goal of maximizing the output power of the energy harvesting and state sensing device to solve for the optimal value of the device size. Taking the peak output of the energy harvesting and state sensing device as the objective, and based on the constraints of formula (7) for the model, the parameter vector x=[ ] = [α, N, a, b, h], where α is the angle between the wedge and the horizontal plane, N is the number of piezoelectric sheets, a, b, h are the length, width, and thickness of the piezoelectric ceramic sheet, respectively, and f(x) is a nonlinear programming function. The constraint functions are nonlinear inequalities, thus yielding the nonlinear programming problem: (10)

[0078] in: (11) (12) (13)

[0079] Formula (10) was simulated using the programming software MATLAB. The optimal solution for x was obtained through the program. The specific data of the angle α between the wedge surface and the horizontal plane, the number of piezoelectric sheets N, the length a, width b, and thickness h of the piezoelectric ceramic sheet were obtained through the optimal solution for x. Based on the actual situation, the optimal solution obtained in this example is x=[85°,60,40mm,40mm,1mm]. After parameter optimization, the device can collect 0.943J of energy in one vehicle-induced vibration cycle, i.e., 5 seconds, with an average power of 0.189W, a peak output voltage of 64V, and a peak output power of 0.745W.

[0080] Actual energy capture and state sensing devices such as Figure 9 As shown.

[0081] Preliminary preparation step two: Determine the optimal matching resistor for the device;

[0082] like Figure 10 , Figure 11 As shown, the vertical force F acting on the device is converted into a horizontal force H(t) by the force transmission mechanism of the device. Under the action of the horizontal force, the positive electric effect of the piezoelectric element is used to generate current and realize energy conversion, where t is time.

[0083] Under the excitation of axial dynamic pressure H(t), in a parallel multilayer piezoelectric stack circuit, the resistance... The voltage response v(t) across the terminals can be expressed by equation (14): (14)

[0084] Efficient capacitor in formula Effective piezoelectric constant .

[0085] Given the horizontal force H(t), the differential equation in equation (14) can be solved recursively using the fourth-order Runge-Kutta Method. Let: (15)

[0086] Where i is the iteration step size and K is the slope of the stage in the numerical integration process, the relationship between the output voltage and the horizontal force H(t) can be calculated from the above formula. Then, the circuit output current I(t), power p(t), and the output energy E of the whole process can be obtained from the following formula. (16) (17) (18)

[0087] As shown in equations (16), (17), and (18), the resistance of a circuit affects the output voltage and output power of the designed device, thus affecting the energy capture efficiency. Therefore, we need to investigate the resistance... The impact on the device's output energy was investigated, and the optimal matching resistance value was obtained. Determining the optimal matching resistance value requires trial and error using experience and formulas to establish a general range. Values ​​within this range are then selected and calculated. Finally, cubic spline interpolation is used to find the maximum value, thus obtaining the optimal matching resistance value. In this example, the optimal resistance value is 5.5kΩ. Finally, the resistance of the external resistor box is adjusted to achieve an overall resistance of approximately 5.5kΩ, thereby maximizing the energy harvesting efficiency. Furthermore, the porous piezoelectric ceramic stack needs to be calibrated to obtain the force-open-circuit voltage curve. At this point, all preparatory work for the formal operation of an energy harvesting and state-sensing device based on porous piezoelectric ceramics is complete.

[0088] In this embodiment, when the floating slab track vibrates under the excitation of train running load, the vibration load is transmitted to the steel spring through the floating slab structure, and further transmitted to the energy harvesting and state sensing device connected in series with the steel spring. The upper cover plate in the device first bears the vertical pressure from the direction of the steel spring and transmits this vertical pressure to the central pressure-bearing block located at the center. The central pressure-bearing block, through its wedge-shaped surface and in cooperation with six sets of radially symmetrically distributed radial sliding blocks, converts the vertical pressure into a horizontal force transmitted radially, amplifying the force by 3.24 times. Subsequently, this horizontal force is applied to six sets of piezoelectric ceramic stacks, causing the piezoelectric ceramic stacks to generate a piezoelectric response under radial pressure. Five sets of commercial PZT-5H piezoelectric ceramic stacks are mainly used to convert the mechanical energy generated by the vibration of the steel spring into electrical energy, while the other set of porous piezoelectric ceramic stacks is mainly used to sense the stress state of the steel spring and output corresponding electrical signals.

[0089] After completing the second preparatory step, the five sets of commercial PZT-5H piezoelectric ceramic stacks are able to harvest electrical energy at maximum energy capture efficiency and input it into the power supply module. In the self-powered interface, alternating power is rectified into pulsating DC power by a full-bridge rectifier, at which point the voltage fluctuates significantly and ripple is present. Subsequently, after processing by the self-powered switch and Buck step-down circuit, the pulsating DC power further reduces the output ripple, resulting in relatively stable DC power at the output. After regulation by the voltage regulator chip, this portion of the power is input into the lithium iron phosphate battery for storage and provides operating power to the data acquisition module and communication module. At the same time, the solar panel serves as an auxiliary power supply unit, converting solar energy into electrical energy when sunlight is available and supplementing the charging of the lithium iron phosphate battery. This, together with the piezoelectric energy harvesting unit, constitutes a hybrid power supply mode to ensure that the system can maintain long-term online monitoring. The voltage regulator chip used in this process is AP64500, which has a quiescent current as low as 25μA, a light load efficiency of up to 85% (5mA load), built-in synchronous rectification, and supports external clock synchronization; the solar panel has a conversion efficiency of 18%~22% and a temperature coefficient of -0.3% / ℃~-0.5% / ℃; the lithium iron phosphate battery supports wide temperature range operation from -20℃ to 60℃ and has a cycle life of >3,000 cycles.

[0090] A porous piezoelectric ceramic stack generates a voltage signal corresponding to the stress state of a steel spring during radial compression. This signal, after signal conditioning, is input to a Microchip PAC1811 digital power monitoring chip. The PAC1811 internally samples, performs analog-to-digital conversion, and averages the input voltage, storing the measurement results in an internal register. An STM32L476RG microcontroller communicates with the PAC1811 via a standard I²C interface. During initialization, it configures the sampling rate, averaging times, and threshold parameters. During operation, it periodically reads the digitized voltage data output by the PAC1811 and performs inverse calculations of the steel spring's stress state based on a pre-calibrated force-open-circuit voltage curve. Subsequently, the microcontroller analyzes, identifies, and stores the collected data to determine the stress changes and vibration state of the steel spring. Simultaneously, it dynamically adjusts the sampling frequency, sleep / wake cycle, and data upload cycle according to system operating requirements to achieve long-term online monitoring under low-power conditions. The Microchip PAC1811 digital power monitoring chip has a measurement accuracy of up to 1% and a typical power consumption of 10mA, making it suitable for low-power applications. The STM32L476RG microcontroller supports multiple interfaces such as I2C and SPI to interact with external devices (such as the PAC1811 chip), and has sufficient memory and computing power to support complex data processing, storage and analysis tasks.

[0091] The stress state and vibration response information of the steel spring, processed by the microcontroller, are uploaded to the cloud platform via a communication module. This communication module uses a LoRa / NB-IoT dual-mode chip, which automatically selects either LoRa or NB-IoT transmission mode based on signal coverage strength, communication quality, and the operating environment. During data transmission, the LoRa / NB-IoT dual-mode chip encapsulates the data output by the microcontroller according to a preset communication protocol and uploads the stress state and vibration response information of the steel spring to the cloud platform. The cloud platform is connected to the communication module to receive monitoring data from field monitoring nodes and performs analysis, storage, classification management, and status updates on the received data. Furthermore, the cloud platform can send the received monitoring data to software terminals and mobile devices to achieve data sharing and remote access across multiple terminals. Finally, maintenance personnel can view the current working status, stress change trends, vibration response, and historical monitoring data of the steel spring in real time through software terminals or mobile devices. Based on the storage and analysis results of the cloud platform, they can perform status assessments, anomaly identification, and maintenance decisions for the floating slab track steel spring components.

[0092] By adopting the above implementation scheme, this embodiment has the following advantages:

[0093] 1. By adopting the above implementation scheme, this embodiment can transmit the vibration mechanical energy of the floating plate track steel spring to the piezoelectric ceramic stack through a force amplification mechanism, realizing the efficient conversion of mechanical energy into electrical energy, thereby significantly improving the system's self-powering capability. Simultaneously, the porous piezoelectric ceramic stack can sense the force state and vibration information of the steel spring in real time, transmitting it to the microcontroller through a data acquisition module, enabling online monitoring and intelligent analysis of the steel spring's mechanical state.

[0094] 2. The porous piezoelectric ceramic was prepared by a water-based synchronous DIW-freeze casting method. Its piezoelectric voltage sensitivity was 4.5V / kPa, and its open-circuit voltage sensitivity was about 50% higher than that of dense PZT stacks under the same load.

[0095] 3. The energy harvesting and state sensing device adopts a structural design combining a modified cymbal-type and multi-layer stacking structure, significantly reducing the overall height of the device to meet the requirement that the internal space height of the steel spring sleeve should not exceed 100mm. Based on this, piezoelectric ceramic sheets are horizontally stacked to form a piezoelectric ceramic stack, increasing the number of layers within a limited vertical dimension, thereby improving the effective working volume and output capacity of the piezoelectric material, achieving the goal of "trading horizontal space for vertical space." Simultaneously, multiple sets of piezoelectric ceramic stacks are arranged axially symmetrically within the device, making the load transfer path more balanced and the structure more stable, which is beneficial to improving the reliability of the energy harvesting process.

[0096] 4. The energy harvesting and state sensing device incorporates a force amplification mechanism. This mechanism, serving as the key path for load transfer, conversion, and amplification, enables the conversion of vertical loads into radial horizontal loads, achieving a good force amplification effect; the force amplification coefficient can reach [value missing]. It has a gain of times greater than that of common similar structures.

[0097] This application also provides an electronic device, including: a processor, and a memory coupled to the processor, the memory being used to store a computer program; the processor being used to execute the computer program stored in the memory, so that the electronic device performs the method as described in any of the above embodiments.

[0098] Electronic devices can be computing devices such as desktop computers, laptops, handheld computers, and cloud servers. These electronic devices may include, but are not limited to, processors and memory.

[0099] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the electronic device, connecting various parts of the device via various interfaces and lines.

[0100] The memory can be used to store the computer program, and the processor implements various functions of the electronic device by running or executing the computer program stored in the memory and calling the data stored in the memory.

[0101] The memory may primarily include a program storage area and a data storage area. The program storage area may store the operating system, applications required for at least one function, etc.; the data storage area may store data created based on the use of the mobile phone, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0102] This application also provides a storage medium, which is a computer-readable storage medium. The computer program is stored in the computer-readable storage medium, and when executed by a processor, the computer program can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0103] This application also provides a computer program product, including: a computer program or instructions that, when the computer program or instructions are run on a computer, cause the computer to perform any of the above possible implementation methods.

[0104] The above description is the preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

Claims

1. An energy harvesting and state self-sensing device, disposed within a steel spring sleeve of a floating plate track and connected in series with a steel spring, characterized in that, It includes an upper cover plate, a lower cover plate, a central pressure block, pre-tightening bolts, six radial sliding blocks, six sets of piezoelectric ceramic stacks corresponding to the six radial sliding blocks, an energy harvesting branch, and a state sensing branch. The upper cover plate and the lower cover plate are connected by the pre-tightening bolts. The central bearing block is located between the upper cover plate and the lower cover plate and can move along the axial direction of the pre-tightening bolts. The six radial sliding blocks are symmetrically distributed around the central bearing block. The lower cover plate has grooves that correspond one-to-one with the six radial sliding blocks and extend radially. The bottom of each radial sliding block is respectively set in the corresponding groove so that the radial sliding block can move radially under the constraint of the groove. Each radial sliding block has a first wedge-shaped abutment on the side facing the central bearing block, and the central bearing block has a second wedge-shaped abutment on the side facing each radial sliding block that cooperates with the first wedge-shaped abutment. Each piezoelectric ceramic stack is respectively set between the corresponding radial sliding block and the inner wall of the enclosure of the lower cover plate. Five of the six sets of piezoelectric ceramic stacks are PZT-5H piezoelectric ceramic stacks, and the output ends of the five sets of PZT-5H piezoelectric ceramic stacks are connected to the energy harvesting branch. The other group is a porous piezoelectric ceramic stack. The output end of the porous piezoelectric ceramic stack is connected to the state sensing branch, which is separate from the energy harvesting branch. The state sensing branch includes a signal conditioning circuit, a data acquisition module, and a microcontroller. The porous piezoelectric ceramic stack is connected to the data acquisition module via the signal conditioning circuit. The microcontroller is used to perform inversion calculation on the open-circuit voltage signal acquired by the data acquisition module according to the pre-calibrated correspondence between force and open-circuit voltage to obtain the force of the steel spring. When the steel spring is compressed under the action of train load, the central bearing block drives each radial sliding block to move radially along the corresponding groove and compress the corresponding piezoelectric ceramic stack through the cooperation between the first wedge-shaped abutment and the second wedge-shaped abutment. This causes the five sets of PZT-5H piezoelectric ceramic stacks to generate electrical energy and causes the porous piezoelectric ceramic stacks to generate an open-circuit voltage signal for inverting the force of the steel spring.

2. The energy harvesting and state self-sensing device according to claim 1, characterized in that, The porous piezoelectric ceramic in the porous piezoelectric ceramic stack is prepared by a water-based synchronous DIW-freeze casting method, and the piezoelectric voltage sensitivity of the porous piezoelectric ceramic is 4.5V / kPa.

3. The energy harvesting and state self-sensing device according to claim 1, characterized in that, Each group of piezoelectric ceramic stacks consists of 60 piezoelectric ceramic sheets stacked together, with adjacent piezoelectric ceramic sheets having opposite polarization directions; copper electrode sheets are provided between adjacent piezoelectric ceramic sheets, the copper electrode sheets having the same planar dimensions as the piezoelectric ceramic sheets and being fully distributed relative to the piezoelectric ceramic sheets.

4. The energy harvesting and state self-sensing device according to claim 1, characterized in that, The preload bolt passes through the central bearing block, which has a central hole through which the preload bolt passes. The diameter of the central hole is larger than the diameter of the preload bolt. Each piezoelectric ceramic stack is fixedly connected to the corresponding radial sliding block and the enclosure of the lower cover plate by epoxy resin. The guide contact surface between the radial sliding block and the groove, and the wedge contact surface between the first wedge abutment and the second wedge abutment, are all provided with a layer of molybdenum disulfide lithium-based grease.

5. The energy harvesting and state self-sensing device according to any one of claims 1-4, characterized in that, It also includes a power supply module, which comprises a self-powered interface, a voltage regulator chip, a solar panel, and a lithium iron phosphate battery. The self-powered interface includes a full-bridge rectifier, a self-powered switch, and a Buck step-down circuit. The output terminals of the five PZT-5H piezoelectric ceramic stacks are connected to the input terminals of the full-bridge rectifier. The full-bridge rectifier, the self-powered switch, the Buck step-down circuit, the voltage regulator chip, and the lithium iron phosphate battery are connected in sequence to rectify, step down, and regulate the alternating power generated by the five PZT-5H piezoelectric ceramic stacks, and store it in the lithium iron phosphate battery. The solar panel is connected to the lithium iron phosphate battery to supplement the power supply to the lithium iron phosphate battery, and the lithium iron phosphate battery is used to power the data acquisition module and the communication module.

6. A self-sensing system for the state of steel springs in a floating slab track, characterized in that, The device includes a track system, an energy harvesting and state sensing device as described in any one of claims 1-4, a power supply module, a communication module, and a cloud platform. The track system includes a box girder, a floating plate suspended on the box girder by steel springs, a track mounted on the floating plate, and a steel spring sleeve disposed within the floating plate to house the steel springs. The power supply module stores the electrical energy generated by the energy harvesting branch and supplies power to the data acquisition module and the communication module. The communication module uploads the steel spring force, force changes, and vibration state obtained by the state sensing branch to the cloud platform.

7. The floating slab track steel spring state self-sensing system according to claim 6, characterized in that, The communication module includes a LoRa / NB-IoT dual-mode chip, which is used to select either LoRa or NB-IoT transmission mode based on signal coverage strength, communication quality, and operating environment. The cloud platform is Alibaba Cloud IoT platform, which is used to receive, parse, store, and classify the force, force changes, and vibration state of the steel spring, and send the corresponding data to the software terminal and mobile phone terminal.

8. A method for designing the size of the energy harvesting and state self-sensing device as described in claim 1, characterized in that, The dimensions of the energy harvesting and state self-sensing device are obtained in the following manner: Where f(x) is a nonlinear programming function, The function is a nonlinear inequality constraint function, where α is the angle between the wedge-shaped contact surface and the horizontal plane. is the force transmission coefficient; μ is the friction coefficient; f is the design value of the device material strength; A is the area of ​​the cross-section of the central bearing block corresponding to the center of the contact surface between the central bearing block and the radial sliding block; F is the external load; parameter vector x=[ ] = [α, N, a, b, h], where N is the number of piezoelectric sheets, a, b, and h are the length, width, and thickness of the piezoelectric ceramic sheets, respectively; lb and ub are the threshold values.

9. The method as described in claim 8, characterized in that, The obtained parameter vector is x=[85°,60,40mm,40mm,1mm].

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