Integrated device for vibration control and energy collection

Abstract

The invention provides an integrated device for vibration control and energy collection. The integrated device comprises a shell, a mass block, a spring assembly, a first electrode pair and a second electrode pair, wherein the mass block is arranged in the shell and can freely vibrate; the spring assembly is arranged between the mass block and the shell and generates a geometric nonlinear effect; the first electrode pair is arranged on the inner side of the shell; the rectifying load circuit is connected with the second electrode pair and the first electrode pair, and the first electrode pair is arranged on the inner side, facing the second electrode pair, of the shell. According to the technical scheme, geometric nonlinearity is introduced through the spring assembly, so that the inherent frequency range of the system covers the ultralow frequency range below 1Hz. According to the technical scheme, the structural vibration response regulation and energy self-supply system is high in adaptability and integration degree, and broadband, stable and efficient combined vibration control and energy recovery are achieved.

Description

Technical field

[0001] The invention relates to an integrated device for vibration control and energy collection. [Background Technology]

[0002] Large civil engineering structures, such as cable-stayed bridges, suspension bridges, super-high-rise buildings, cable structures, or flexible components, often exhibit significant ultra-low frequency vibration characteristics, with vibration frequencies typically below 1 Hz. Although these vibration sources have extremely low frequencies, their displacement amplitudes are large, and long-term accumulation can easily lead to structural fatigue, reduced comfort, and even damage risks. Therefore, effective control of these vibrations is of great engineering significance. Existing passive vibration control devices, such as tuned mass dampers (TMDs) and liquid dampers (TLDs), mostly rely on tuning at specific frequency points, making it difficult to address issues such as frequency drift and multimodal response in ultra-low frequency environments. In particular, the control effect is limited under complex excitation conditions such as wind-induced or secondary seismic disturbances.

[0003] At the same time, effectively harnessing these continuous, low-frequency vibrations for energy harvesting is a key area of ​​focus for current structural self-powered systems. Common energy harvesting methods include piezoelectric, electromagnetic, and electrostatic. Piezoelectric materials rely on material strain to stimulate charge output, but their performance is highly dependent on vibration frequency and response rate, with significant output degradation at very low frequencies. Electromagnetic energy harvesting requires relative motion to generate an induced current, but its voltage and current outputs depend on relative velocity, making it difficult to adapt to low-frequency vibration conditions and subject to bulky structures and layout constraints. Triboelectric nanogenerators (TENGs), a recently emerging energy harvesting technology, theoretically can generate charge output at low frequencies. However, their energy conversion process relies on surface contact and periodic separation, leading to long-term contact wear, poor output stability, and limited device life. Particularly in civil structures with frequencies below 1 Hz and large displacement amplitudes, TENG devices often fail to maintain continuous output due to insufficient contact or slip.

[0004] In contrast, the electrostatic energy harvesting mechanism based on the principle of capacitance change does not rely on high-speed or high-frequency contact, but only relies on displacement drive to generate charge modulation, making it suitable for low-frequency and large-displacement working conditions. However, most existing electrostatic energy harvesting structures have not been designed in a coordinated manner with nonlinear vibration control devices, lacking efficient integrated implementation methods. Although some studies have attempted to combine control and energy harvesting functions, most of them adopt a functional series connection method, with the control structure and energy harvesting mechanism being independent of each other. There is a lack of deep coordination in the structural coupling mechanism and response mode, resulting in complex and inefficient overall system response. In particular, in unstable low-frequency environments, the "double failure" problem of control failure and energy harvesting shutdown is more likely to occur.

[0005] In summary, the existing technical solutions combining vibration control with energy harvesting have the following shortcomings:

[0006] (1) Difficult to adapt to ultra-low frequency vibration environments: Traditional piezoelectric and electromagnetic energy harvesting devices rely on high-frequency and high-speed motion to obtain effective energy output. They are almost ineffective under ultra-low frequency vibration conditions below 1 Hz, which limits their application scope in large civil structures.

[0007] (2) Lack of deep coordination between vibration control and energy harvesting functions: Existing control-energy harvesting integration solutions mostly adopt a series design, and the control device and the energy harvesting unit structure and response are not related to each other, resulting in low system operation efficiency. Especially in an environment with obvious frequency fluctuations, there is a "double failure" problem of weakened control and unstable energy harvesting.

[0008] (3) Narrow control bandwidth and insufficient adaptability: Most existing passive control devices such as TMD and TLD are only tuned to a certain frequency point and lack the ability to adapt to excitation frequency drift or multimodal response. It is difficult to achieve wide-band stable control in practical applications. [Summary of the invention]

[0009] The purpose of the present invention is to provide an integrated device of an integrated mass block, spring assembly, electrode and electret for vibration control and energy harvesting. Through a nonlinear stiffness and capacitance adjustment mechanism, the device can realize the structural vibration response regulation and energy self-supply functions. The frequency response range covers ultra-low frequency vibration control below 1.0 Hz and energy recovery with electrostatic energy harvesting output power ≥10 mW.

[0010] To achieve the above-mentioned purpose of the invention, the present invention provides an integrated device for vibration control and energy harvesting, characterized in that the integrated device includes a shell, a mass block arranged in the shell and capable of vibrating freely, a spring assembly arranged between the mass block and the shell for generating a geometric nonlinear effect, a first electrode pair arranged on the inner side of the shell, a second electrode pair arranged on the mass block, a rectifier load circuit connecting the second electrode pair and the first electrode pair, and the first electrode pair is arranged on the inner side of the shell facing the second electrode pair.

[0011] As a further improvement of one embodiment of the present invention, the integrated device also includes a damper connected between the mass block and the shell, the damper is connected to the upper end surface of the mass block, and the second electrode pair is arranged on the lower end surface of the mass block, and the lower end surface is opposite to the upper end surface.

[0012] As a further improvement of an embodiment of the present invention, the damper is a viscous fluid damper.

[0013] As a further improvement of one embodiment of the present invention, the integrated device further includes an electret located between the second electrode pair and the first electrode pair.

[0014] As a further improvement of an embodiment of the present invention, the electret is disposed on the first electrode pair, and the electret is disposed on a side of the first electrode pair facing the second electrode pair.

[0015] As a further improvement of one embodiment of the present invention, the material of the electret is selected from polytetrafluoroethylene, polypropylene or fluorinated ethylene propylene copolymer.

[0016] As a further improvement of one embodiment of the present invention, the spring assembly includes at least two coil springs symmetrically arranged along the circumferential direction, and the extension direction of the coil spring is perpendicular to the vibration direction of the mass block; the spring assembly introduces geometric nonlinear deformation in vertical movement to form a third-order stiffness restoring force.

[0017] As a further improvement of an embodiment of the present invention, the material of the first electrode pair is copper foil or aluminum foil.

[0018] As a further improvement of an embodiment of the present invention, the rectifier load circuit includes a rectifier unit, an energy storage unit and a voltage stabilizing unit.

[0019] As a further improvement of one embodiment of the present invention, the shell has a sealed annular cavity, the mass block is configured as an annular mass block, the mass block, the spring assembly, the first electrode pair and the second electrode pair are all located in the annular cavity, the first electrode pair is located on the inner side surface of the outer ring portion of the shell, and the second electrode pair is located on the outer peripheral surface of the mass block.

[0020] Compared with existing technologies, the present invention offers the following advantages: a combined control device capable of achieving control capabilities and electrostatic energy harvesting within an ultra-low frequency range below 1.0 Hz in ultra-low frequency, large-displacement vibration environments, with an output power exceeding 10 mW. Utilizing a spring assembly within the device that generates geometric nonlinear effects and an electrode pair motion coupling mechanism, the device simultaneously regulates vibration response while stably driving capacitance changes, enabling electrostatic energy harvesting with an output power exceeding 10 mW. This device also improves the robustness and functional synergy of the system in complex vibration environments. This integrated technology specifically targets ultra-low frequency, high-amplitude vibration characteristics, fully leveraging the advantages of electrostatic energy harvesting at large displacements and integrating nonlinear structural response characteristics to enhance the vibration control range and adaptability. This organically integrates the nonlinear vibration control mechanism with electrostatic energy harvesting, leveraging the relative motion of the mass within the structure to achieve the dual effects of damping energy dissipation and capacitance changes, combining broadband vibration suppression capabilities with energy harvesting efficiency. The goal is to construct a highly adaptable and integrated structural vibration response regulation and energy self-sustaining system, achieving broadband, stable, and efficient combined vibration control and energy recovery.

Brief Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without inventive efforts. Among them:

[0022] Figure 1 A schematic diagram of an integrated device provided in a first embodiment of the present invention;

[0023] Figure 2 for Figure 1 Main view of the integrated device installed on the bridge;

[0024] Figure 3 for Figure 1 A top view of the integrated device installed on the bridge;

[0025] Figure 4 yes Figure 1 Circuit diagram of the rectifier load circuit in the integrated device;

[0026] Figure 5 yes Figure 1 Schematic diagram of the relationship between the energy harvesting power and energy consumption power of the integrated device;

[0027] Figure 6 A schematic diagram of an integrated device provided in a second embodiment of the present invention installed on a stay cable;

[0028] Figure 7 for Figure 6 Cross-sectional view of the integrated device at AA;

[0029] Figure 8 for Figure 6 Cross-sectional view of the integrated device at point BB;

[0030] Figure 9 for Figure 6 Cross-sectional view of the integrated device CC. [Specific implementation method]

[0031] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It will be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some, rather than all, structures related to the present application are shown in the accompanying drawings. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0032] As used herein, the terms "comprise," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0033] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0036] See also Figures 1 to 3 As shown, the first embodiment provided by the present invention provides an integrated device for vibration control and energy harvesting, wherein the integrated device includes a shell 1, a mass block 2 arranged in the shell 1 and capable of vibrating freely, a spring assembly 3 laterally arranged between the mass block 2 and the shell 1, a first electrode pair 4 arranged on the inner side of the shell 1, a second electrode pair 5 arranged on the mass block 2, and a rectifier load circuit 6 connecting the second electrode pair 5 and the first electrode pair 4, and the first electrode pair 4 is arranged on the inner side of the shell 1 facing the second electrode pair 5.

[0037] When in use, the integrated device is fixed to the structure to be tested. Taking the application of a bridge as an example, the integrated device is fixed to the box girder of the main beam structure 10 of the bridge through the fastening structure 9.

[0038] Furthermore, the integrated device includes a damper 7 connected between the mass block 2 and the housing 1. One end of the damper 7 is connected to the upper end surface of the mass block 2. The second electrode pair 5 is disposed on the lower end surface of the mass block 2, with the lower end surface facing away from the upper end surface. Furthermore, the other end of the damper 7 is connected to the inside of the housing 1.

[0039] The spring assembly 3 and housing 1 form a geometrically nonlinear configuration with third-order cubic stiffness characteristics. Damper 7 dissipates structural vibration energy. When mass 2 drives the second electrode pair 5 relative to the first electrode pair 4, a change in capacitance occurs.

[0040] Through the technical solution of this invention, the structural vibration drives the mass block 2 to generate vertical movement in the shell 1, and while driving the damper 7 to dissipate the vibration energy, it stimulates the horizontally arranged spring assembly 3 to generate geometric nonlinear deformation, forming a nonlinear restoring force, and improving the broadband control capability of the integrated device; at the same time, the movement of the mass block 2 causes the relative displacement between the second electrode pair 5 and the first electrode pair 4, resulting in a periodic change in capacitance. Under the action of the electrostatic field established by the electret 8, electrostatic induction is realized and the load circuit is driven to output energy, completing the integration of efficient energy collection and control functions in an ultra-low frequency vibration environment.

[0041] The present invention proposes a combined control device capable of achieving control capabilities and electrostatic energy harvesting within an ultra-low frequency range below 1.0 Hz in ultra-low frequency, large-displacement vibration environments, with an output power exceeding 10 mW. The device utilizes a spring assembly (3) within the device that generates geometric nonlinear effects and an electrode pair motion coupling mechanism to simultaneously drive capacitance changes while achieving vibration response control, achieving high-efficiency energy harvesting and improving the system's robustness and functional synergy in complex vibration environments. This integrated technology specifically targets ultra-low frequency, high-amplitude vibration characteristics, fully leveraging the advantages of electrostatic energy harvesting's capacitance changes under large displacements. It also combines the nonlinear structural response characteristics to enhance the vibration control range and adaptability, thereby organically integrating the nonlinear vibration control mechanism with the electrostatic energy harvesting function. The device leverages the relative motion of the mass (2) within the structure to achieve the dual effects of damping energy dissipation and capacitance changes, combining broadband vibration suppression capabilities with energy harvesting efficiency. The goal is to build a highly adaptable and integrated structural vibration response control and energy self-sustaining system, achieving broadband, stable, and efficient combined vibration control and energy recovery.

[0042] The spring assembly 3 includes at least two coil springs symmetrically arranged along the circumferential direction, and the extending direction of the coil springs is perpendicular to the vibration direction of the mass block 2 .

[0043] The integrated device also includes an electret 8 located between the second electrode pair 5 and the first electrode pair 4. The built-in electric field of electret 8 drives charge redistribution during capacitance changes, generating an electrostatically induced current. Furthermore, a rectifier load circuit 6 completes charge transfer and energy output.

[0044] The working principle of the specific embodiment provided by this invention is as follows: This integrated device achieves synchronous response through tuned coupling between the main structure and the device. When the structure vibrates due to external excitation (such as wind load, earthquake, or operational disturbance), the integrated device moves with the structure, and the internal mass block 2 moves relative to the housing 1 due to inertia.

[0045] The mass block 2 is connected to the spring assemblies 3 arranged on both sides of it. The structural movement drives the mass block 2 up and down, causing the spring assemblies 3 to stretch. Since the spring assemblies 3 are arranged horizontally, geometric nonlinear effects are introduced in the vertical movement, forming a nonlinear tuned mass system:

[0046]

[0047] in, is the nonlinear restoring force generated by the lateral geometric nonlinear deformation of the spring component 3, k n is the cubic stiffness coefficient, and x is the relative displacement of mass block 2. Due to the nonlinear stiffness characteristics, the system can be adjusted within the natural frequency of the main structure in the ultra-low frequency (<1Hz) range. (where k is the main structural stiffness and m is the main structural mass) with a wide-band tuning function within a ±50% variation range, thereby improving the system's control robustness to excitations of different frequencies.

[0048] At the same time, during the vertical movement of the mass block 2, the second electrode pair 5 fixed thereon moves relative to each other in the up and down directions, and the electrodes form a relative capacitance C with the fixed electrodes inside the housing 1:

[0049]

[0050] Where ε is the dielectric constant, A is the motor area, and d(t) is the time-varying electrode spacing. When mass 2 drives the second electrode pair 5 up and down, the electrode spacing changes, causing a change in capacitance C.

[0051] Because electret 8 is sandwiched between the second electrode pair 5 and the first electrode pair 4, its built-in electric field drives charge redistribution during the capacitance change, forming an electrostatically induced current in the circuit. This current is then transmitted to the load resistor via a rectifier load circuit, converting mechanical energy into electrical energy. This process does not rely on high-frequency excitation, but instead utilizes the large displacement characteristics of the structure, making it suitable for ultra-low-frequency vibration environments. The harvested electrical energy can be used to power low-power wireless monitoring equipment or replenish local energy storage systems.

[0052] During the structural vibration process, this device forms a closed-loop energy mechanism that self-responds, self-consumes, and self-collects energy. It has the dual functions of vibration control and electrostatic energy collection, and significantly improves the frequency band response range through nonlinear configuration. It is suitable for typical ultra-low frequency vibration scenarios such as high-rise buildings, bridge main beams, and inclined cables.

[0053] In this embodiment, the housing 1 is constructed of a cylindrical aluminum alloy. Specifically, the housing 1 is formed from a monolithic extruded aluminum alloy. Furthermore, it may include embedded ribs and guide rails to enhance the overall rigidity of the housing 1, resulting in excellent structural strength and vibration damping. The interior of the housing 1 is sprayed with an insulating coating to improve the system's resistance to electromagnetic interference. The housing 1 has a protection rating of at least IP65, making it suitable for use in humid, dusty, and windy environments.

[0054] The electret 8 is disposed on the first electrode pair 4 , and the electret 8 is disposed on a side of the first electrode pair 4 facing the second electrode pair 5 .

[0055] The electret 8 is made of a material selected from polytetrafluoroethylene, polypropylene, or fluorinated ethylene-propylene copolymer. Its surface is treated with corona discharge or electron beam irradiation to impart stable charge storage capacity. Electret 8 is securely attached to the outer surface of the first electrode pair 4 via a polymer adhesive, providing a continuous built-in electric field during the relative motion of the second electrode pair 5 and the first electrode pair 4, driving electrostatic energy conversion.

[0056] Mass block 2 is made of Q235 structural steel and can be assembled with custom mass.

[0057] The damper 7 is a viscous fluid damper 7. This configuration can enhance the energy dissipation capability of the mass 2 movement and play a vibration reduction role under large structural responses. Specifically in this embodiment, the viscous fluid damper 7 can be configured as a silicone oil damper.

[0058] The first electrode pair 4 is made of copper or aluminum foil and is tightly mounted on the inner wall of the housing 1, securely bonded to the housing 1 via an insulating adhesive layer. The movable second electrode pair 5 is circumferentially attached to the lower end surface of the mass 2, and the reciprocating inertial motion of the mass 2 drives the movable second electrode pair 5 to periodically change its spacing with the fixed first electrode pair 4.

[0059] Further references Figure 4, the rectifier load circuit 6 includes a rectifier unit 6a, an energy storage unit 6b and a voltage stabilizing unit 6c. The rectifier load circuit 6 specifically includes an integrated bridge rectifier unit, a capacitor energy storage device and a DC-DC voltage stabilizing unit. The second electrode pair 5 and the first electrode pair 4 are respectively led to the input end of the circuit module through wires. After rectification and voltage stabilization, the electrostatically converted charge can output stable DC power for use by low-power sensors, wireless nodes or other microelectronic components. In order to ensure structural safety and electrical insulation, the rectifier load circuit 6 is encapsulated in an insulating cabin outside the shell 1 and is isolated and installed from the shell 1 by an anti-vibration rubber pad.

[0060] Figure 5 Energy harvesting power for integrated devices and device power consumption The diagram clearly and specifically illustrates that an energy harvesting power greater than 10 mW can be achieved in ultra-low frequency vibration below 1 Hz.

[0061] like Figures 6 to 9 As shown, the second embodiment provided by the present invention has the same working principle as the first embodiment. The differences between this embodiment and the first embodiment are described in detail below.

[0062] The structure to be tested, for which the integrated device provided in this embodiment is applied, has a cable-stayed structure. For example, a cable-stayed bridge has a cable 11. During use, the cable 11 extends through both ends of a housing 13 and is connected to the housing 13 via a fixing device 12. During use, one end of the cable 11 is fixed to the ground, and the other end is fixed to the structure to be tested.

[0063] In addition, in this embodiment, the housing 13 has a sealed annular cavity 14, and the mass 15 is provided as an annular mass 15. The mass 15, the spring assembly, the first electrode pair 16, and the second electrode pair 17 are all located in the annular cavity 14. The first electrode pair 16 is located on the inner side surface of the outer ring portion of the housing 13, and the second electrode pair 17 is located on the outer circumferential surface of the mass 15. The electret 18 is provided on the first electrode pair 16.

[0064] The spring assembly includes four transverse coil springs 19 extending in a first direction and four longitudinal coil springs 20 extending in a second direction. Specifically, the first direction and the second direction are perpendicular to each other. The four transverse coil springs 19 are symmetrically arranged in pairs with respect to the inclined cable 11, and the four longitudinal coil springs 20 are also symmetrically arranged in pairs with respect to the inclined cable 11. Taking the two transverse coil springs 19 located on one side of the cable as an example, one end of the outer transverse coil spring 19 is connected to the inner side surface of the outer ring portion of the housing 13, and the other end of the outer transverse coil spring 19 is connected to the outer circumferential surface of the annular mass 15; while one end of the inner transverse coil spring 19 is connected to the inner side surface of the inner ring portion of the housing 13, and the other end of the inner transverse coil spring 19 is connected to the inner circumferential surface of the annular mass 15.

[0065] When the annular mass block 15 moves along the first direction with the oblique cable 11, the four transverse coil springs 19 are obliquely deformed; when the annular mass block 15 moves along the second direction with the oblique cable 11, the four longitudinal coil springs 20 are obliquely deformed.

[0066] The mass block 15 is annular and cylindrical, which can be assembled into a customized mass. Under the excitation of the cable structure, the mass block 15 reciprocates horizontally or vertically along the inclined cable 11, forming a bidirectional inertial response path relative to the housing 13.

[0067] In this preferred embodiment, the rectifier load circuit 21 is located outside the housing 13 .

[0068] The above is only a specific embodiment of the present invention, and any other improvements made based on the concept of the present invention are considered to be within the protection scope of the present invention.

Claims

1. An integrated device for vibration control and energy harvesting, characterized in that: The integrated device includes a shell, a mass block arranged in the shell and capable of vibrating freely, a spring assembly arranged between the mass block and the shell for generating a geometric nonlinear effect, a first electrode pair arranged on the inner side of the shell, a second electrode pair arranged on the mass block, a rectifier load circuit connecting the second electrode pair and the first electrode pair, and the first electrode pair is arranged on the inner side of the shell facing the second electrode pair.

2. The integrated device according to claim 1, characterized in that: The integrated device further includes a damper connected between the mass block and the housing, the damper being connected to the upper end surface of the mass block, and the second electrode pair being arranged on the lower end surface of the mass block, the lower end surface being opposite to the upper end surface.

3. The integrated device according to claim 2, characterized in that: The damper is a viscous fluid damper.

4. The integrated device according to claim 1, characterized in that: The integrated device further includes an electret located between the second electrode pair and the first electrode pair.

5. The integrated device according to claim 4, characterized in that: The electret is disposed on the first electrode pair, and the electret is disposed on a side of the first electrode pair facing the second electrode pair.

6. The integrated device according to claim 4, characterized in that: The material of the electret is selected from polytetrafluoroethylene, polypropylene or fluorinated ethylene propylene copolymer.

7. The integrated device according to claim 1, characterized in that: The spring assembly includes at least two coil springs symmetrically arranged along the circumferential direction, and the extension direction of the coil spring is perpendicular to the vibration direction of the mass block; the spring assembly introduces geometric nonlinear deformation during vertical movement to form a third-order stiffness restoring force.

8. The integrated device according to claim 1, characterized in that: The first electrode pair is made of copper foil or aluminum foil.

9. The integrated device according to claim 1, characterized in that: The rectifier load circuit includes a rectifier unit, an energy storage unit and a voltage stabilizing unit.

10. The integrated device according to claim 1, characterized in that: The shell has a sealed annular cavity, and the mass block is configured as an annular mass block. The mass block, spring assembly, first electrode pair and second electrode pair are all located in the annular cavity. The first electrode pair is located on the inner side surface of the outer ring portion of the shell, and the second electrode pair is located on the outer peripheral surface of the mass block.

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