Self-powered overpressure sensor with zero vibration noise

Abstract

The application provides a zero-vibration-noise self-powered overpressure sensor, which comprises a differential sensing module for picking up an overpressure signal and a triboelectric vibration absorber for power supply inside, the differential sensing module is composed of an overpressure sensing unit and a vibration sensing unit, the two sensing units have the same structural parameters and are both composed of a PVDF piezoelectric film, and high signal-to-noise ratio overpressure signal measurement with zero vibration noise is realized by combining the differential denoising technology in electronic information; the triboelectric vibration absorber is composed of a copper inner cylinder, a copper outer cylinder, a damping spring and a PDMS friction pad, the copper inner cylinder and the PDMS friction pad form a friction pair, the parasitic vibration noise energy is converted into electric energy by using the triboelectric effect, the built-in circuit is powered, and thus the self-powered overpressure sensor with high dynamic range and high signal-to-noise ratio is realized; and this will provide a powerful tool for explosion shock wave power evaluation and research on shock wave propagation law.

Description

Technical Field

[0001] This invention relates to the field of shock wave overpressure measurement, and specifically to a self-powered overpressure sensor with zero vibration noise. Background Technology

[0002] Overpressure sensors are a key component of explosion shock wave power assessment systems and form the basis for studying shock wave propagation laws and establishing finite element models of explosion shock waves. Traditional overpressure sensors suffer from high cost, significant parasitic vibration noise, and poor electromagnetic interference resistance, causing numerous inconveniences for on-site explosion shock wave testing. Domestic research on overpressure sensors started relatively late, and currently, relevant units mostly use imported products from foreign companies (PCB (USA), Kistler (Switzerland)) for shock wave measurements. These products are expensive, and their ability to suppress parasitic vibration noise is poor. The quality of the measured overpressure data is highly dependent on the material of the object being measured and the installation method. When the object being measured is a large plate-like structure or the sensor is loosely installed, the overpressure signal measured by these products is superimposed with the parasitic vibration signal, significantly reducing the signal-to-noise ratio of the overpressure signal. Furthermore, the sensitive elements of imported overpressure sensors often use piezoelectric ceramics. While the manufacturing process of piezoelectric ceramics is mature, they are brittle and easily break under large impacts, which limits the measurement range of these products.

[0003] PVDF piezoelectric film is a flexible, lightweight, and highly tough film that can be fabricated into components of various shapes and thicknesses as needed. Combined with microelectronics technology, it can support multifunctional sensing elements. Compared with traditional piezoelectric materials (such as ceramic piezoelectric sheets), it has advantages such as wide frequency response (0-500MHz), large dynamic range, high force-point conversion sensitivity, and high impact strength (>20GPa). With the rapid development and deep integration of materials science and electronic information science, PVDF piezoelectric film can be used as a sensing unit. The sensor structure can simultaneously design overpressure sensing units and vibration sensing units. By utilizing differential denoising technology in electronic information, an overpressure sensing unit with strong impact resistance and low parasitic vibration noise can be designed. Furthermore, a vibration damping structure can be designed for the overpressure sensing unit. The relatively sliding parts of the damping mechanism use triboelectric materials to convert parasitic vibration noise energy into electrical energy using the triboelectric effect, thus powering the built-in circuitry. This achieves a cable-free, self-powered overpressure sensor with high dynamic range and high signal-to-noise ratio. This will provide a powerful tool for assessing the power of explosive shock waves and studying the propagation laws of shock waves. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art and provide a self-powered overpressure sensor with zero vibration and noise.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A self-powered overpressure sensor with zero vibration and noise includes a square plate-shaped overpressure sensor base, a cylindrical metal housing with an opening at the bottom and a circular through-hole at the center of the top fixedly connected to the overpressure sensor base, and a cylindrical metal differential sensing module for picking up overpressure signals disposed inside the overpressure sensor housing. The top opening of the differential sensing module extends from the circular through-hole at the center of the top of the overpressure sensor housing and does not contact the overpressure sensor housing. A ring-shaped circuit board is located outside the differential sensor and is fixedly connected to the overpressure sensor base via a circuit board support. The bottom of the differential sensing module is... A square plate-shaped fixed base is fixed and insulated at the center of its upper surface. The four corners of the lower surface of the fixed base are fixed and electrically connected to the upper ends of four triboelectric vibration absorbers made of metal material that convert vibration into electrical energy and transmit the electrical energy to the circuit board through the fixed base. The lower ends of the triboelectric vibration absorbers are fixed and insulated to the overpressure sensor base. The differential sensing module is provided with an overpressure sensing unit located at the top that deforms due to external overpressure and vibration and outputs overpressure and vibration signals, and a vibration sensing unit located at the bottom that deforms due to external vibration and outputs vibration signals. Both the overpressure sensing unit and the vibration sensing unit include a circular PVDF piezoelectric film.

[0007] The upper surface and the lower surface of the overpressure sensing unit are insulated from each other. The lower surface of the overpressure sensing unit is electrically connected to the upper surface of the vibration sensing unit. Both the upper surface and the lower surface of the overpressure sensing unit are insulated from each other.

[0008] The upper surface of the overpressure sensing unit, the lower surface of the overpressure sensing unit, the upper surface of the vibration sensing unit, the lower surface of the vibration sensing unit, and the fixing base are all electrically connected to the circuit board.

[0009] Further technical solutions include:

[0010] The differential sensor includes an annular differential sensing module cover at the top. The lower end of the differential sensing module cover is fixed and insulated from the upper end of a cylindrical differential sensing module middle cylinder located below, which has a sealed cavity on the upper side of a columnar overpressure sensing unit signal electrode and a sealed cavity on the lower side of a columnar vibration sensing unit ground electrode. The lower end of the differential sensing module middle cylinder is fixed and insulated from the upper end of a cylindrical differential sensing module base located below, which has a sealed cavity on the upper side of a columnar vibration sensing unit signal electrode. The lower end of the differential sensing module base is fixed and insulated from the center of the upper surface of the fixed base. The differential sensing module cover, the differential sensing module middle cylinder, and the differential sensing module base are coaxially arranged. The upper end of the differential sensing module cover extends out from a circular through hole at the center of the top of the overpressure sensor housing and does not contact the overpressure sensor housing.

[0011] A circular overpressure sensing unit is clamped and fixed between the top cover and the middle cylinder of the differential sensing module. A circular vibration sensing unit is clamped and fixed between the middle cylinder and the base of the differential sensing module. The overpressure sensing unit and the vibration sensing unit have the same structure. The upper surface of the PVDF piezoelectric film has a sensing unit ground electrode with the same diameter as the overpressure sensing unit and the vibration sensing unit. The lower surface of the PVDF piezoelectric film has a concentric circular sensing unit signal electrode with a smaller diameter than the overpressure sensing unit and the vibration sensing unit. Inside the sealed cavity on the electrode side, there is a cylindrical middle cylinder coaxially arranged with the middle cylinder of the differential sensing module. The signal electrode of the sensing unit on the lower surface of the cylinder support is attached to and completely overlapped with the upper surface of the cylinder support using conductive adhesive. The ground electrode of the sensing unit on the upper surface of the overpressure sensing unit is in contact with the outside air through the opening of the differential sensing module cover. Inside the sealed cavity on the signal electrode side of the vibration sensing unit, there is a cylindrical base support coaxially arranged with the base of the differential sensing module. The signal electrode of the sensing unit on the lower surface of the vibration sensing unit is attached to and completely overlapped with the upper surface of the base support using conductive adhesive. The ground electrode of the sensing unit on the upper surface of the vibration sensing unit is in contact with the air inside the sealed cavity on the ground electrode side of the vibration sensing unit.

[0012] The circuit board integrates a differential amplifier circuit and an energy harvesting circuit. The ground electrode of the overpressure sensing unit on the upper surface is electrically connected to the cover of the differential sensing module, and the cover of the differential sensing module is connected to the differential amplifier circuit on the circuit board via an overpressure signal line. The signal electrode of the overpressure sensing unit on the lower surface of the overpressure sensing unit is connected to the middle cylinder of the differential sensing module via a support pillar. The ground electrode of the vibration sensing unit on the upper surface of the vibration sensing unit is electrically connected to the middle cylinder of the differential sensing module, and the middle cylinder of the differential sensing module is connected to the differential amplifier circuit on the circuit board via a ground wire. The unit signal electrode of the vibration sensing unit on the lower surface of the vibration sensing unit is electrically connected to the base of the differential sensing module via a support pillar of the differential sensing module base, and the base of the differential sensing module is connected to the differential amplifier circuit on the circuit board via a vibration signal line. The fixed base is electrically connected to the energy harvesting circuit on the circuit board via a power line. The triboelectric vibration absorber is electrically connected to the energy harvesting circuit on the circuit board via the fixed base.

[0013] The triboelectric vibration absorber includes a hollow cylindrical copper inner cylinder with a closed bottom and an open top, located at the bottom. A hollow cylindrical copper outer cylinder with a closed top and an open bottom is fitted onto the inner cylinder. A damping spring is installed between the inner and outer cylinders. The lower end of the damping spring is fixedly connected to the inner bottom surface of the inner cylinder with oil-based adhesive, and the upper end is fixedly connected to the inner top surface of the outer cylinder with oil-based adhesive. When fully compressed, the damping spring is located within the inner cylinder. The cylindrical surface of the inner cavity of the outer cylinder is covered with conductive adhesive. A layer of PDMS friction pad is provided. There is a gap between the PDMS friction pad and the shock-absorbing spring. The shock-absorbing spring is insulated from the outer copper cylinder and the inner copper cylinder. The friction surface of the PDMS friction pad is in contact with the outer surface of the inner copper cylinder. The conductive layer of the PDMS friction pad is in contact with the outer copper cylinder. The overpressure sensor base has a cylindrical groove for fixing the corresponding inner copper cylinder. The inner copper cylinder is fixed in the cylindrical groove on the corresponding overpressure sensor base with insulating glue. The upper end of the outer copper cylinder is fixedly connected to the lower surface of the fixing base with conductive glue.

[0014] The lower end of the differential sensing module cover has an internal thread, and the upper end of the differential sensing module cylinder has an external thread. Both the internal thread at the lower end of the differential sensing module cover and the external thread at the upper end of the differential sensing module cylinder are electroplated with an insulating coating. The threaded connection between the lower end of the differential sensing module cover and the upper end of the differential sensing module cylinder makes the lower end of the differential sensing module cover and the upper end of the differential sensing module cylinder fixed and insulated.

[0015] The lower end of the differential sensing module cylinder has an internal thread, and the upper end of the differential sensing module base has an internal thread. Both the internal threads at the lower end of the differential sensing module cylinder and the internal threads at the upper end of the differential sensing module base are electroplated with an insulating coating. The lower end of the differential sensing module cylinder is threadedly connected to the upper end of the differential sensing module base, thus fixing and insulating the lower end of the differential sensing module cylinder.

[0016] The sensing unit signal electrode is a layer of silver electrode coated on the lower surface of the PVDF piezoelectric film, and the sensing unit ground electrode is a layer of silver electrode coated on the lower surface of the PVDF piezoelectric film.

[0017] The lower end of the overpressure sensor housing has an internal thread, and the overpressure sensor base has an annular boss with an external thread that mates with the internal thread at the lower end of the overpressure sensor housing. The overpressure sensor housing and the overpressure sensor base are threadedly fixedly connected, making them electrically connected.

[0018] The differential sensing module's top cover, middle cylinder, and base are all made of aluminum alloy using CNC machining.

[0019] Both the outer and inner cylinders are made of brass.

[0020] The shock-absorbing spring is a spring made of high-molecular plastic material.

[0021] The PDMS friction pad is made from PDMS prepolymer by spin coating and has a thickness of 200µm.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The present invention provides a self-powered overpressure sensor with zero vibration noise, which uses a differential sensing module that integrates an overpressure sensing unit and a vibration sensing unit. One side of the overpressure sensing unit is open to the external atmosphere, while the other side is located in a sealed cavity. Both external overpressure and vibration will cause deformation of the overpressure sensing unit, so the output of the overpressure sensing unit includes both overpressure and vibration signals. The vibration sensing unit is located in a sealed cavity on both sides, so the output of the vibration sensing unit only contains vibration signals. The two units are made of two PVDF piezoelectric films with identical parameters. Therefore, their output vibration signals are completely identical. The outputs of the two units are connected to a differential amplifier on a circuit board. The output of the differential amplifier only contains overpressure information, thus achieving zero parasitic vibration noise.

[0024] (2) The present invention provides a self-powered overpressure sensor with zero vibration noise. Both the overpressure sensing unit and the vibration sensing unit use PVDF piezoelectric film, which is soft, lightweight and tough. It can be made into elements of various shapes and thicknesses as needed. Compared with traditional piezoelectric materials (such as ceramic piezoelectric sheets), it has the characteristics of wide frequency response (0-500MHz), large dynamic range, high force point conversion sensitivity and high impact strength (>20GPa).

[0025] (3) The present invention provides a self-powered overpressure sensor with zero vibration and noise. The differential sensing module is not directly rigidly connected to the overpressure sensor housing, but is buffered by a triboelectric vibration absorber. Most of the high-frequency parasitic vibrations caused by overpressure are absorbed by the triboelectric vibration absorber, and only a small portion of the remaining energy acts on the differential sensing module.

[0026] (4) The present invention provides a self-powered overpressure sensor with zero vibration noise. The damping material of the triboelectric vibration absorber is a PDMS friction pad. The PDMS friction pad and the copper inner cylinder form a sliding friction pair, which converts the vibration energy absorbed by the triboelectric vibration absorber into electrical energy. The electrical energy is stored by the energy harvesting circuit on the circuit board and used by other energy-consuming units, thereby realizing the self-powering of the overpressure sensor.

[0027] (5) The present invention provides a self-powered overpressure sensor with zero vibration and noise. The overpressure sensor housing is made of aluminum alloy with high conductivity, which has strong anti-electromagnetic interference capability and ensures that the collected overpressure data has an ultra-high signal-to-noise ratio. Attached Figure Description

[0028] The invention will now be further described with reference to the accompanying drawings:

[0029] Figure 1 This is a schematic diagram of the external structure of a self-powered overpressure sensor with zero vibration and noise provided by the present invention.

[0030] Figure 2 This is a schematic diagram of the internal structure of a self-powered overpressure sensor with zero vibration and noise provided by the present invention.

[0031] Figure 3 This is a detailed structural diagram of a differential sensing module provided by the present invention.

[0032] Figure 4 A detailed structural schematic diagram of a triboelectric vibration absorber provided by the present invention.

[0033] Figure 5 This is a schematic diagram of the structure of the lower surface of the overpressure sensing unit and the vibration sensing unit in this invention.

[0034] Figure 6This is a schematic diagram of the structure of the upper surface of the overpressure sensing unit and the vibration sensing unit in this invention.

[0035] In the diagram: 1. Overpressure sensor housing, 2. Differential sensing module, 3. Circuit board, 4. Overpressure sensor base, 5. Triboelectric vibration absorber, 6. Fixed base, 7. Circuit board support, 8. Power cord, 9. Vibration signal line, 10. Ground wire, 11. Overpressure signal line, 12. Differential sensing module top cover, 13. Differential sensing module middle cylinder, 14. Overpressure sensing unit signal electrode side sealing cavity, 15. Vibration sensing unit ground electrode side sealing cavity, 16. Vibration sensing unit signal electrode side sealing cavity, 17. Differential sensing module base, 18. Differential sensing module base support, 19. Vibration sensing unit, 20. Differential sensing module middle cylinder support, 21. Overpressure sensing unit, 22. Copper outer cylinder, 23. PDMS friction pad, 24. Shock-absorbing spring, 25. Copper inner cylinder, 26. Sensing unit signal electrode, 27. Sensing unit ground electrode. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings:

[0037] This invention provides a self-powered overpressure sensor with zero vibration and noise, such as... Figure 1 and Figure 2 The diagram shows an overpressure sensor base 4 made of a square plate-shaped metal material. A cylindrical overpressure sensor housing 1, with an opening at the bottom and a circular through-hole at the center of the top, is fixedly connected to the bottom of the overpressure sensor base 4. Inside the overpressure sensor housing 1 is a cylindrical differential sensing module 2 made of metal material for picking up overpressure signals. The top opening of the differential sensing module 2 extends from the circular through-hole at the center of the top of the overpressure sensor housing 1 and does not contact the housing. A ring-shaped circuit board 3 is located outside the differential sensor 2 and is fixedly connected to the overpressure sensor base 4 via a circuit board support 7. The bottom of the differential sensing module 2 is fixed and insulated from the center of the upper surface of a square plate-shaped fixed base 6. The four corners of the lower surface of the fixed base 6 are fixed and electrically connected to the upper ends of four triboelectric vibration absorbers 5 made of metal material that convert vibration into electrical energy and transmit the electrical energy to the circuit board 3 through the fixed base 6. The lower ends of the triboelectric vibration absorbers 5 are fixed and insulated from the overpressure sensor base 4. Figure 3 As shown, the differential sensing module 2 is provided with an overpressure sensing unit 21 located at the top, which is deformed by external overpressure and vibration and outputs overpressure signal and vibration signal, and a vibration sensing unit 19 located at the bottom, which is deformed by external vibration and outputs vibration signal. Both the overpressure sensing unit 21 and the vibration sensing unit 19 include a circular PVDF piezoelectric film.

[0038] The upper surface and the lower surface of the overpressure sensing unit 21 are insulated from each other. The lower surface of the overpressure sensing unit 21 is electrically connected to the upper surface of the vibration sensing unit 19. Both the upper surface and the lower surface of the overpressure sensing unit 21 are insulated from each other.

[0039] The upper surface of the overpressure sensing unit 21, the lower surface of the overpressure sensing unit 21, the upper surface of the vibration sensing unit 19, the lower surface of the vibration sensing unit 19, and the fixed base 6 are all electrically connected to the circuit board 3.

[0040] In this embodiment, as Figure 3 As shown, the differential sensor 2 includes an annular differential sensing module cover 12 located at the top. The lower end of the differential sensing module cover 12 is fixedly and insulatedly connected to the upper end of a cylindrical differential sensing module middle cylinder 13 located below, which has a sealed cavity 14 on the upper side with a columnar overpressure sensing unit signal electrode and a sealed cavity 15 on the lower side with a columnar vibration sensing unit ground electrode. The lower end of the differential sensing module middle cylinder 13 is connected to a sealed cavity 15 located below, which has a sealed cavity 14 on the upper side with a columnar overpressure sensing unit signal electrode. The upper end of the cylindrical differential sensing module base 17 of the sealing cavity 16 on the signal electrode side of the motion sensing unit is fixed and insulated. The lower end of the differential sensing module base 17 is fixed and insulated at the center of the upper surface of the fixed base 6. The differential sensing module cover 12, the differential sensing module middle cylinder 13 and the differential sensing module base 17 are coaxially arranged. The upper end of the differential sensing module cover 12 extends out from the circular through hole at the center of the top of the overpressure sensor housing 1 and does not contact the overpressure sensor housing 1.

[0041] A circular overpressure sensing unit 21 is clamped and fixed between the differential sensing module upper cover 12 and the differential sensing module middle cylinder 13. A circular vibration sensing unit 19 is clamped and fixed between the differential sensing module middle cylinder 13 and the differential sensing module base 17. The overpressure sensing unit 21 and the vibration sensing unit 19 have the same structure. Figure 6 As shown, the upper surface of the 56µm thick PVDF piezoelectric film has a sensing unit ground electrode 27 with the same diameter as the overpressure sensing unit 21 and the vibration sensing unit 19, as shown. Figure 5As shown, the lower surface of the PVDF piezoelectric film has a concentric circular sensing unit signal electrode 26 with a diameter smaller than that of the overpressure sensing unit 21 and the vibration sensing unit 19. Inside the electrode-side sealed cavity 14, there is a cylindrical middle cylinder support 20 coaxially arranged with the middle cylinder 13 of the differential sensing module. The sensing unit signal electrode 26 on the lower surface of the overpressure sensing unit 21 is attached to and completely overlapped with the upper surface of the middle cylinder support 20 and bonded with conductive adhesive. The sensing unit ground electrode 27 on the upper surface of the overpressure sensing unit 21 is in contact with the outside air through the opening of the differential sensing module cover 12. Inside the vibration sensing unit signal electrode-side sealed cavity 16, there is a cylindrical base support 18 coaxially arranged with the differential sensing module base 17. The sensing unit signal electrode 26 on the lower surface of the vibration sensing unit 19 is attached to and completely overlapped with the upper surface of the base support 18 and bonded with conductive adhesive. The sensing unit ground electrode 27 on the upper surface of the vibration sensing unit 19 is in contact with the air inside the vibration sensing unit ground electrode-side sealed cavity 15.

[0042] Circuit board 3 integrates a differential amplifier circuit and an energy harvesting circuit. The ground electrode 27 of the sensing unit on the upper surface of the overpressure sensing unit 21 is electrically connected to the upper cover 12 of the differential sensing module, and the upper cover 12 of the differential sensing module is connected to the differential amplifier circuit on circuit board 3 through the overpressure signal line 11. The signal electrode 26 of the overpressure sensing unit on the lower surface of the overpressure sensing unit 21 is connected to the middle cylinder 13 of the differential sensing module through the middle cylinder support 20 of the differential sensing module. The ground electrode 27 of the vibration sensing unit on the upper surface of the vibration sensing unit 19 is connected to the middle cylinder 13 of the differential sensing module. Electrically connected, the cylinder 13 of the differential sensing module is connected to the differential amplifier circuit on the circuit board 3 through the ground wire 10, the unit signal electrode 26 on the lower surface of the vibration sensing unit 19 is electrically connected to the differential sensing module base 17 through the differential sensing module base support 18, and the differential sensing module base 17 is connected to the differential amplifier circuit on the circuit board 3 through the vibration signal line 9, the fixed base 6 is electrically connected to the energy harvesting circuit on the circuit board 3 through the power line 8, and the triboelectric vibration absorber 5 is electrically connected to the energy harvesting circuit on the circuit board 3 through the fixed base 6.

[0043] In this embodiment, as Figure 4As shown, the triboelectric vibration absorber 5 includes a hollow cylindrical copper inner cylinder 25 located at the bottom with a closed bottom and an open top. A hollow cylindrical copper outer cylinder 22 with a closed top and an open bottom is fitted on the copper inner cylinder 25. Both the copper outer cylinder 22 and the copper inner cylinder 25 are made of brass. A shock-absorbing spring 24 is installed between the copper inner cylinder 25 and the copper outer cylinder 22. The shock-absorbing spring 24 is made of high-molecular plastic. The lower end of the shock-absorbing spring 24 is fixedly connected to the inner bottom surface of the copper inner cylinder 25 with oil-based adhesive, and the upper end of the shock-absorbing spring 24 is fixedly connected to the inner top surface of the copper outer cylinder 22 with oil-based adhesive. When fully compressed, the shock-absorbing spring 24 is located inside the copper inner cylinder 25. A layer of PDMS friction pad 23 is adhered and covered to the cylindrical surface of the inner cavity of the copper outer cylinder 22 with conductive adhesive. The PDMS friction pad 23 is made of PDMS prepolymer by spin coating and has a thickness of 200um. There is a gap between the S-friction pad 23 and the damping spring 24. The damping spring 24 is insulated from the copper outer cylinder 22 and from the copper inner cylinder 25. The friction surface of the PDMS friction pad 23 is in contact with the outer surface of the copper inner cylinder 25. The conductive layer of the PDMS friction pad 23 is in contact with the copper outer cylinder 22. The PDMS friction pad 23 acts as a damping material to consume the elastic potential energy of the damping spring 24. On the other hand, it forms a sliding friction pair with the copper inner cylinder 25. It uses the triboelectric effect to convert mechanical energy into electrical energy and transmits it to the circuit board 3 through the copper outer cylinder 22, the fixed base 6 and the power line 8.

[0044] The overpressure sensor base 4 has a cylindrical groove for fixing the corresponding copper inner cylinder 25. The copper inner cylinder 25 is fixed in the cylindrical groove on the corresponding overpressure sensor base 4 with insulating glue. The upper end of the copper outer cylinder 22 is fixedly connected to the lower surface of the fixing base 6 with conductive glue.

[0045] In this embodiment, as Figure 3 As shown, the lower end of the differential sensing module cover 12 has an internal thread, and the upper end of the differential sensing module cylinder 13 has an external thread. Both the internal thread at the lower end of the differential sensing module cover 12 and the external thread at the upper end of the differential sensing module cylinder 13 are electroplated with an insulating coating. The lower end of the differential sensing module cover 12 and the upper end of the differential sensing module cylinder 13 are threadedly connected to fix the lower end of the differential sensing module cover 12 and the upper end of the differential sensing module cylinder 13 and provide an insulated connection.

[0046] In this embodiment, as Figure 3As shown, the lower end of the differential sensing module cylinder 13 has an internal thread, and the upper end of the differential sensing module base 17 has an internal thread. Both the internal threads at the lower end of the differential sensing module cylinder 13 and the upper end of the differential sensing module base 17 are electroplated with an insulating coating. The lower end of the differential sensing module cylinder 13 is threadedly connected to the upper end of the differential sensing module base 17, thus fixing and insulating the lower end of the differential sensing module cylinder 13. The differential sensing module cover 12, the differential sensing module cylinder 13, and the differential sensing module base 17 are all made of aluminum alloy through CNC machining.

[0047] In this embodiment, as Figure 5 As shown, the sensing unit signal electrode 26 is a layer of silver electrode coated on the lower surface of the PVDF piezoelectric film, such as... Figure 6 As shown, the sensing unit ground electrode 27 is a layer of silver electrode coated on the lower surface of the PVDF piezoelectric film.

[0048] In this embodiment, a person, such as Figure 2 As shown, the lower end of the overpressure sensor housing 1 has an internal thread, and the overpressure sensor base 4 has an annular boss. The annular boss has an external thread that mates with the internal thread at the lower end of the overpressure sensor housing 1. The overpressure sensor housing 1 and the overpressure sensor base 4 are threadedly fixedly connected, making the overpressure sensor housing 1 and the overpressure sensor base 4 electrically connected.

[0049] When performing overpressure measurements, the overpressure sensor may be installed on the ground surface, wooden board surface, or steel plate surface, depending on the on-site conditions. When the shock wave propagates to the vicinity of the sensor, the external excitation acting on the overpressure sensor includes not only the overpressure signal but also the parasitic vibration caused by the overpressure. The differential sensing module 2 in this invention simultaneously includes an overpressure sensing unit 21 and a vibration sensing unit 19. The overpressure sensing unit 21, because one side is connected to the external air environment while the other side is in a sealed cavity, will simultaneously sense both the overpressure signal and the parasitic vibration signal. The vibration sensing unit 19, because both sides are in sealed cavities, will only sense the parasitic vibration signal. After the outputs of the overpressure sensing unit 21 and the vibration sensing unit 19 are passed through the differential amplifier circuit on the circuit board 3, the output signal contains only the overpressure signal, thus achieving zero vibration noise output. The differential sensing module 2 is connected to the overpressure sensor base 4 via four triboelectric vibration absorbers 5. Most of the parasitic vibration energy will be absorbed by the damping spring 24 of the triboelectric vibration absorber 5 and converted into vibration between the copper outer cylinder 22 and the copper inner cylinder 25 of the triboelectric vibration absorber 5. The friction between the PDMS friction pad 23 attached to the inner surface of the copper outer cylinder 22 and the copper inner cylinder 25 will consume the elastic potential energy of the damping spring 24 and convert it into electrical energy through the triboelectric effect, and then transmit it to the circuit board 3 through the copper outer cylinder 22, the fixed base 6 and the power line 8.

[0050] The following is a brief description of the general manufacturing method of a zero-vibration-noise self-powered overpressure sensor provided by the present invention.

[0051] (1) Fabrication of overpressure sensing unit 21 and vibration sensing unit 19

[0052] Two 17mm diameter circular pieces are cut from a 56µm thick PVDF melt-cast film to form two circular PVDF piezoelectric films. The upper surfaces of the two PVDF piezoelectric films are coated with silver electrodes to serve as ground electrodes 27 of the sensing unit. A 5mm diameter circular silver electrode with the same diameter as the differential sensing module base support 18 and the differential sensing module middle cylinder support 20 is coated at the center of the lower surface of the two PVDF piezoelectric films to serve as the sensing unit signal electrode 26.

[0053] (2) Fabrication of differential sensing module 2

[0054] The differential sensing module upper cover 12, differential sensing module middle cylinder 13, and differential sensing module base 17 are manufactured by CNC machining.

[0055] A differential sensing module cylinder support column 20 is located at the center of the cavity of the differential sensing module cylinder 13, and a differential sensing module base support column 18 is located at the center of the cavity of the differential sensing module base 17. An overpressure sensing unit 21 is installed at the top of the upper cavity of the differential sensing module cylinder 13. The sensing unit signal electrode 26 of the overpressure sensing unit 21 is completely aligned with the upper surface of the differential sensing module cylinder support column 20, and the two are bonded together with conductive adhesive, providing sufficient mechanical contact force and electrical connection. A vibration sensing unit 19 is installed at the top of the cavity of the differential sensing module base 17. The sensing unit signal electrode 26 of the vibration sensing unit 19 is completely aligned with the upper surface of the base support column 18, and the two are bonded together with conductive adhesive, providing sufficient mechanical contact force and electrical connection. Under standard atmospheric pressure, tightening the threads between the lower end of the differential sensing module upper cover 12 and the top end of the differential sensing module middle cylinder 13 clamps the overpressure sensing unit 21 with the overlapping portion of their projections. The upper cavity of the differential sensing module middle cylinder 13 forms the overpressure sensing unit signal electrode side sealing cavity 14. Under standard atmospheric pressure, tightening the threads between the bottom end of the differential sensing module middle cylinder 13 and the upper end of the differential sensing module base 17 clamps the vibration sensing unit 19. The lower cavity of the differential sensing module middle cylinder 13 and the upper cavity of the differential sensing module base 17 respectively form the vibration sensing unit ground electrode side sealing cavity 15 and the vibration sensing unit signal electrode side sealing cavity 16.

[0056] (3) Preparation of the fixed base 6

[0057] The fixing base 6 is CNC machined on the aluminum alloy substrate.

[0058] (4) Preparation of PDMS friction pad 23

[0059] Using PDMS liquid prepolymer as raw material, a PDMS film with a thickness of 200 μm was prepared by spin coating. The film was then cut into rectangular strips with the same area as the inner cylindrical surface of the copper outer cylinder 22 to complete the preparation of the PDMS friction pad 23.

[0060] (5) Preparation of triboelectric vibration absorber 5

[0061] A copper outer cylinder 22 and a copper inner cylinder 25 are CNC machined onto a brass substrate. A PDMS friction pad 23 is bonded to the cylindrical inner surface of the copper outer cylinder 22 using conductive adhesive, providing sufficient mechanical contact force while ensuring electrical connection. Oil-based adhesive is applied to the inner bottom surface of the copper inner cylinder 25, allowing the lower end of the damping spring 24 to contact the inner surface of the copper inner cylinder 25. After the oil-based adhesive cures, oil-based adhesive is applied to the inner bottom surface of the copper outer cylinder 22. The damping spring 24, connecting the copper inner cylinder 25, is then inserted into the copper outer cylinder 22. The upper and lower end faces of the copper outer cylinder 22 and the copper inner cylinder 25 are pressed down. After the oil-based adhesive cures, the assembly of the triboelectric vibration absorber 5 is complete.

[0062] (6) Fabrication of circuit board 3

[0063] The circuit board 3 integrates a differential amplifier, an energy harvesting and storage circuit, and a wireless data acquisition module.

[0064] (7) Preparation of overpressure sensor housing 1 and overpressure sensor base 4

[0065] The overpressure sensor housing 1 and the overpressure sensor base 4 are CNC machined on an aluminum alloy substrate.

[0066] (8) Overpressure sensor assembly

[0067] Through the above steps, the overpressure sensor base 4, overpressure sensor housing 1, differential sensing module 2, circuit board 3, fixed base 6, and triboelectric vibration absorber 5 have been prepared.

[0068] The assembly of an overpressure sensor consists of two steps: mechanical assembly and electrical connection.

[0069] The mechanical assembly steps are as follows:

[0070] The copper inner cylinder 25 of the triboelectric vibration absorber 5 is installed in the mounting hole of the cylindrical groove structure of the overpressure sensor base 4, and the two are bonded together with insulating adhesive. The upper part of the copper outer cylinder 22 of the four triboelectric vibration absorbers 5 is fixedly connected to the four corner points of the lower surface of the fixed base 6, and the two are bonded together with conductive adhesive to form an electrical connection. A differential sensing module base 17 is inserted into a coaxial circular groove structure mounting hole on the top of the fixed base 6, and the two are bonded together with oil-based adhesive for insulation. The circuit board 3 is fixedly installed on the circuit board support 7 of the overpressure sensor base 4 by threaded engagement. The external thread of the annular boss of the overpressure sensor base 4 is threadedly connected to the lower end external thread of the overpressure sensor housing 1.

[0071] The electrical connection steps are as follows:

[0072] Solder one end of a 0.2mm diameter power cable 8 to the outer surface of the mounting base 6, and the other end of the power cable 8 to the circuit board 3. Solder one end of a 0.15mm diameter vibration signal cable 9 to the differential sensor module base 17, and the other end of the vibration signal cable 9 to the circuit board 3. Solder one end of a 0.15mm diameter ground wire 10 to the differential sensor module cylinder 13, and the other end of the ground wire 10 to the circuit board 3. Solder one end of a 0.15mm diameter overpressure signal cable 11 to the differential sensor module cover 12, and the other end of the overpressure signal cable 11 to the circuit board 3.

Claims

1. A self-powered overpressure sensor with zero vibration and noise, characterized in that, The system includes a square plate-shaped overpressure sensor base (4), a cylindrical metal housing (1) with an opening at the bottom and a circular through hole at the center of the top, the bottom of which is fixedly connected to the overpressure sensor base (4). Inside the overpressure sensor housing (1) is a cylindrical metal differential sensing module (2) for picking up overpressure signals. The top opening of the differential sensing module (2) extends from the circular through hole at the center of the top of the overpressure sensor housing (1) and does not contact the overpressure sensor housing (1). A ring-shaped circuit board (3) is located outside the differential sensing module (2) and is fixedly connected to the overpressure sensor base (4) via a circuit board support (7). The bottom of the differential sensing module (2) is connected to a square plate-shaped metal housing. The center of the upper surface of the fixed base (6) is fixed and insulated. The four corners of the lower surface of the fixed base (6) are fixed and electrically connected to the upper ends of four triboelectric vibration absorbers (5) made of metal material that convert vibration into electrical energy and transmit electrical energy to the circuit board (3) through the fixed base (6). The lower end of the triboelectric vibration absorber (5) is fixed and insulated connected to the overpressure sensor base (4). The differential sensing module (2) is provided with an overpressure sensing unit (21) located at the top that deforms due to external overpressure and vibration and outputs overpressure signal and vibration signal, and a vibration sensing unit (19) located at the bottom that deforms due to external vibration and outputs vibration signal. Both the overpressure sensing unit (21) and the vibration sensing unit (19) include a circular PVDF piezoelectric film. The upper surface of the overpressure sensing unit (21) and the lower surface of the overpressure sensing unit (21) are insulated from each other. The lower surface of the overpressure sensing unit (21) is electrically connected to the upper surface of the vibration sensing unit (19). The upper surface of the overpressure sensing unit (21) and the lower surface of the overpressure sensing unit (21) are both insulated from the lower surface of the vibration sensing unit (19). The upper surface of the overpressure sensing unit (21), the lower surface of the overpressure sensing unit (21), the upper surface of the vibration sensing unit (19), the lower surface of the vibration sensing unit (19), and the fixed base (6) are all electrically connected to the circuit board (3). The differential sensing module (2) includes an annular differential sensing module cover (12) located at the top. The lower end of the differential sensing module cover (12) is fixed and insulatedly connected to the upper end of a cylindrical differential sensing module middle cylinder (13) located below, which has a sealed cavity (14) on the upper part with a columnar overpressure sensing unit signal electrode side and a sealed cavity (15) on the lower part with a columnar vibration sensing unit ground electrode side. The lower end of the differential sensing module middle cylinder (13) is fixed and insulatedly connected to the upper end of a cylindrical differential sensing module base (17) located below, which has a sealed cavity (16) on the upper part with a columnar vibration sensing unit signal electrode side. The lower end of the differential sensing module base (17) is fixed and insulatedly connected to the center of the upper surface of the fixed base (6). The sensor module cover (12), the differential sensor module cylinder (13), and the differential sensor module base (17) are coaxially arranged. A circular overpressure sensing unit (21) is clamped and fixed between the differential sensor module cover (12) and the differential sensor module cylinder (13). A circular vibration sensing unit (19) is clamped and fixed between the differential sensor module cylinder (13) and the differential sensor module base (17). The overpressure sensing unit (21) and the vibration sensing unit (19) have the same structure. There is a cylindrical cylinder support (20) in the electrode side sealing cavity (14) that is coaxially arranged with the differential sensor module cylinder (13). There is a cylindrical base support (18) in the vibration sensing unit signal electrode side sealing cavity (16) that is coaxially arranged with the differential sensor module base (17).

2. The self-powered overpressure sensor with zero vibration and noise according to claim 1, characterized in that, The upper end of the differential sensing module cover (12) extends from the circular through hole at the center of the top of the overpressure sensor housing (1) and does not contact the overpressure sensor housing (1); the upper surface of the PVDF piezoelectric film has a sensing unit ground electrode (27) with the same diameter as the overpressure sensing unit (21) and the vibration sensing unit (19); the lower surface of the PVDF piezoelectric film has a concentric circular sensing unit signal electrode (26) with a smaller diameter than the overpressure sensing unit (21) and the vibration sensing unit (19); the sensing unit signal electrode on the lower surface of the overpressure sensing unit (21) ( 26) The upper surface of the middle cylinder support (20) is attached and completely overlapped with the upper surface of the overpressure sensing unit (21) and bonded with conductive adhesive. The sensing unit ground electrode (27) on the upper surface of the overpressure sensing unit (21) is in contact with the outside air through the opening of the differential sensing module cover (12). The sensing unit signal electrode (26) on the lower surface of the vibration sensing unit (19) is attached and completely overlapped with the upper surface of the base support (18) and bonded with conductive adhesive. The sensing unit ground electrode (27) on the upper surface of the vibration sensing unit (19) is in contact with the air in the sealing cavity (15) on the ground electrode side of the vibration sensing unit. The circuit board (3) integrates a differential amplifier circuit and an energy harvesting circuit. The sensing unit ground electrode (27) on the upper surface of the overpressure sensing unit (21) is electrically connected to the differential sensing module cover (12). The differential sensing module cover (12) is connected to the differential amplifier circuit on the circuit board (3) through the overpressure signal line (11). The overpressure sensing unit signal electrode (26) on the lower surface of the overpressure sensing unit (21) is connected to the differential sensing module cylinder (13) through the differential sensing module cylinder support (20). The vibration sensing unit ground electrode (27) on the upper surface of the vibration sensing unit (19) is electrically connected to the differential sensing module cylinder (13). The differential sensing module cylinder (13) is connected to the differential amplifier circuit on the circuit board (3) via the ground wire (10). The unit signal electrode (26) on the lower surface of the vibration sensing unit (19) is electrically connected to the differential sensing module base (17) via the differential sensing module base support (18). The differential sensing module base (17) is connected to the differential amplifier circuit on the circuit board (3) via the vibration signal line (9). The fixed base (6) is electrically connected to the energy harvesting circuit on the circuit board (3) via the power line (8). The triboelectric vibration absorber (5) is electrically connected to the energy harvesting circuit on the circuit board (3) via the fixed base (6).

3. The self-powered overpressure sensor with zero vibration and noise according to claim 2, characterized in that, The triboelectric vibration absorber (5) includes a hollow cylindrical copper inner cylinder (25) with a closed bottom and an open top located below. A hollow cylindrical copper outer cylinder (22) with a closed top and an open bottom is fitted onto the copper inner cylinder (25). A damping spring (24) is provided between the copper inner cylinder (25) and the copper outer cylinder (22). The lower end of the damping spring (24) is fixedly connected to the inner bottom surface of the copper inner cylinder (25) with oily glue, and the upper end of the damping spring (24) is fixedly connected to the inner top surface of the copper outer cylinder (22) with oily glue. When fully compressed, the damping spring (24) is located in the copper inner cylinder (25). A layer of PDM is adhered and covered on the cylindrical surface of the inner cavity of the copper outer cylinder (22) with conductive glue. There is a gap between the S friction pad (23) and the shock-absorbing spring (24). The shock-absorbing spring (24) is insulated from the outer copper cylinder (22). The shock-absorbing spring (24) is insulated from the inner copper cylinder (25). The friction surface of the PDMS friction pad (23) is in contact with the outer surface of the inner copper cylinder (25). The conductive layer of the PDMS friction pad (23) is in contact with the outer copper cylinder (22). The overpressure sensor base (4) has a cylindrical groove for fixing the corresponding inner copper cylinder (25). The inner copper cylinder (25) is fixed in the cylindrical groove on the corresponding overpressure sensor base (4) by insulating glue. The upper end of the outer copper cylinder (22) is fixedly connected to the lower surface of the fixing base (6) by conductive glue.

4. A self-powered overpressure sensor with zero vibration and noise according to claim 2, characterized in that, The lower end of the differential sensing module cover (12) has an internal thread, and the upper end of the differential sensing module cylinder (13) has an external thread. Both the internal thread at the lower end of the differential sensing module cover (12) and the external thread at the upper end of the differential sensing module cylinder (13) are electroplated with an insulating coating. The lower end of the differential sensing module cover (12) and the upper end of the differential sensing module cylinder (13) are threadedly connected, so that the lower end of the differential sensing module cover (12) and the upper end of the differential sensing module cylinder (13) are fixed and insulatedly connected. The lower end of the differential sensing module cylinder (13) has an internal thread, and the upper end of the differential sensing module base (17) has an internal thread. The internal threads at the lower end of the differential sensing module cylinder (13) and the internal threads at the upper end of the differential sensing module base (17) are both electroplated with an insulating coating. The lower end of the differential sensing module cylinder (13) is threadedly connected to the upper end of the differential sensing module base (17), so that the lower end of the differential sensing module cylinder (13) is fixed and insulated.

5. A self-powered overpressure sensor with zero vibration and noise according to claim 2, characterized in that, The sensing unit signal electrode (26) is a layer of silver electrode coated on the lower surface of the PVDF piezoelectric film, and the sensing unit ground electrode (27) is a layer of silver electrode coated on the lower surface of the PVDF piezoelectric film.

6. A self-powered overpressure sensor with zero vibration and noise according to any one of claims 1 to 5, characterized in that, The lower end of the overpressure sensor housing (1) has an internal thread, and the overpressure sensor base (4) has an annular boss. The annular boss has an external thread that mates with the internal thread at the lower end of the overpressure sensor housing (1). The overpressure sensor housing (1) and the overpressure sensor base (4) are threadedly fixedly connected, making the overpressure sensor housing (1) and the overpressure sensor base (4) electrically connected.

7. A self-powered overpressure sensor with zero vibration and noise according to any one of claims 2 to 5, characterized in that, The differential sensing module cover (12), the differential sensing module cylinder (13), and the differential sensing module base (17) are all made of aluminum alloy material by CNC machining.

8. A self-powered overpressure sensor with zero vibration and noise according to claim 3, characterized in that, Both the outer copper cylinder (22) and the inner copper cylinder (25) are made of brass.

9. A self-powered overpressure sensor with zero vibration and noise according to claim 3, characterized in that, The shock-absorbing spring (24) is a spring made of polymer plastic.

10. A self-powered overpressure sensor with zero vibration and noise according to claim 3, characterized in that, The PDMS friction pad (23) is made of PDMS prepolymer by spin coating and has a thickness of 200um.

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