A shear-based acceleration and pressure compound sensor and an assembling method thereof

Abstract

The application is a kind of acceleration and pressure composite sensor based on shear type and its assembling method, belonging to the field of composite sensor. The technical scheme is as follows: a kind of acceleration and pressure composite sensor based on shear type structure: the acceleration detection module includes mass block of positive polygonal prism structure, each side surface of the mass block is provided with acceleration sensitive ceramic sheet; the pressure detection module includes force transmission column of positive polygonal prism structure, each side surface of the force transmission column is provided with pressure sensitive ceramic sheet, electrode sheet and insulating block. The sensitive elements of the acceleration sensor and the pressure sensor core body in the scheme are arranged in polygon, forming a space stereo structure, which improves the effective area of the sensitive elements in unit volume, multiple sensitive elements jointly act, forming the superposition of pressure signal, ensuring the detection accuracy and sensitivity of both, and then greatly reducing the overall volume of the composite sensor under the premise of maintaining the original accuracy, so that the composite sensor can be miniaturized.

Description

Technical Field

[0001] This invention relates to the field of composite sensors, and in particular to a shear-based acceleration and pressure composite sensor and its assembly method. Background Technology

[0002] Piezoelectric acceleration and pressure sensors use piezoelectric materials as sensing elements to measure acceleration and pressure physical quantities under external force. They are typically composed of core components such as a housing and a sensing element, and are widely used in industrial monitoring, aerospace and other fields.

[0003] However, traditional piezoelectric sensors are limited by the stacked sensing unit structure design, resulting in a contradiction between size and functional integration: on the one hand, if the sensitivity needs to be improved, the area of ​​the piezoelectric ceramic needs to be increased, and the corresponding electrode sheet, mass block, insulating sheet, and sensor shell also need to be increased, thus increasing the overall size of the sensor; on the other hand, the size of the composite sensor itself is significantly increased compared to independent sensors. If acceleration and pressure parameters need to be monitored simultaneously, conventional solutions must adopt a combined installation mode with separate independent acceleration and pressure sensors. Moreover, due to the limitations of the overall size, it is usually difficult to install them in the same location, resulting in differences in the acquisition timing of multiple sensors, which leads to poor signal synchronization and makes it difficult to meet the needs of scenarios that require collaborative analysis of multiple physical quantities. It also increases the complexity of installation operations.

[0004] Shear sensors utilize the shear effect to achieve a piezoelectric coefficient far exceeding that of compression-type structures, giving them a natural advantage in enhancing sensitivity. However, the structural design of existing shear sensors is still not perfect. As independent sensors, they still require the traditional arrangement of multiple sensors installed independently, making them unsuitable for miniaturized, high-precision monitoring scenarios. Summary of the Invention

[0005] This invention addresses the problems of current pressure and acceleration sensors being either independently installed or having a large volume of composite structure. It provides a shear-based composite acceleration and pressure sensor that significantly reduces the size while maintaining sensitivity.

[0006] To solve the above problems, the technical solution adopted by the present invention is a shear-based acceleration and pressure composite sensor, comprising an upper shell and a lower shell, wherein an acceleration detection module and a pressure detection module are provided between the upper shell and the lower shell; the acceleration detection module includes an acceleration core and an acceleration core shell, the acceleration core including an acceleration core mass block, the acceleration core mass block having a regular polygonal prism structure, and each side of the acceleration core mass block being provided with an acceleration-sensitive ceramic sheet; the acceleration core shell surrounds the outer periphery of the acceleration core, and the acceleration-sensitive ceramic sheet... The pressure plate is pressed between the outer peripheral surface of the acceleration core mass block and the inner peripheral surface of the acceleration core shell; the pressure detection module includes a pressure core and a pressure core shell, the pressure core includes a force transmission column, the force transmission column is located at the center of the upper surface of the lower shell, the force transmission column is a regular polygonal prism structure, each side of the force transmission column is provided with a pressure-sensitive ceramic plate, an electrode plate and an insulating block from the inside out, the edges of adjacent electrode plates are in contact with each other, and the pressure-sensitive ceramic plate, the electrode plate and the insulating block are pressed between the outer peripheral surface of the force transmission column and the inner peripheral surface of the pressure core shell. This solution, based on a shear-type design, provides a novel structure for a composite acceleration and pressure sensor. The sensitive elements of both the acceleration and pressure sensor cores are arranged in a polygonal pattern, forming a three-dimensional spatial structure. This increases the effective area of ​​the sensitive elements per unit volume. In the acceleration detection module, a mass block serves as the output, with various acceleration-sensitive ceramic plates attached to its outer periphery superimposing the acceleration signals. In the pressure detection module, a force transmission column simultaneously drives various pressure-sensitive ceramic plates, causing multiple electrode plates to contact each other and superimpose pressure signals. This ensures the detection accuracy and sensitivity of both sensors, thereby significantly reducing the overall size of the composite sensor while maintaining its original accuracy. This miniaturization facilitates its deployment in confined spaces. Furthermore, the acceleration and pressure detection modules are coaxially arranged vertically with a unified shear direction, improving the synchronization of the two signals and providing more realistic data support for multi-physical quantity analysis.

[0007] As a preferred implementation of a shear-based acceleration and pressure composite sensor, the acceleration core housing comprises multiple acceleration core housing units, each located outside the acceleration-sensitive ceramic sheet. Each acceleration core housing unit is a trapezoidal prism structure. The sides of the corresponding trapezoidal sides of the multiple acceleration core housing units are sequentially abutted and fixedly connected. The acceleration-sensitive ceramic sheet is pressed between the acceleration core mass block and the side of the corresponding trapezoidal short base of the corresponding acceleration core housing unit. Similarly, the pressure core housing comprises multiple pressure core housing units, located outside the insulating block. Each pressure core housing unit is a trapezoidal prism structure. The sides of the corresponding trapezoidal sides of the multiple pressure core housing units are sequentially abutted and fixedly connected. The pressure-sensitive ceramic sheet, the electrode sheet, and the insulating block are pressed between the outer circumferential surface of the force transmission column and the side of the corresponding trapezoidal short base of the corresponding pressure core housing unit. The outer shell is disassembled into multiple trapezoidal units, which are then connected by abutting the sides of the trapezoids to form a complete shell. The trapezoidal structure provides guidance and applies a uniform and stable preload to the internal sensitive elements, avoiding the problem of inaccurate preload in traditional monolithic shells. The preload is applied to the individual shell units by external clamps, and then welded after clamping. This avoids the springback phenomenon after pressure application in traditional narrow-diameter designs, ensuring stable preload and guaranteeing detection accuracy. At the same time, the modular design facilitates individual installation and adjustment of sensitive elements on different sides, reducing assembly difficulty. Furthermore, the welded fixation maintains the preload for a long time, improving the stiffness and structural stability of the sensor's elastic system, thereby ensuring the long-term reliability of detection accuracy.

[0008] As a preferred implementation of a shear-based composite acceleration and pressure sensor, both the acceleration core mass block and the force transmission column are regular hexagonal prisms; the cross-sections of both the acceleration core shell and the pressure core shell are isosceles trapezoids with a base angle of 60 degrees. The regular hexagonal prism structure provides six evenly distributed mounting surfaces, allowing for the arrangement of more sensitive ceramic plates within the same volume, further enhancing signal superposition and detection sensitivity. The isosceles trapezoidal shell with a 60-degree base angle matches the side surface of the regular hexagonal prism, forming a regular hexagonal shell after splicing, ensuring consistent preload on each sensitive element and avoiding detection errors caused by uneven force distribution. Furthermore, the regular hexagonal structure possesses excellent force transmission characteristics and structural stability, reducing the impact of external forces on the internal core, making it suitable for detection needs under harsh working conditions.

[0009] As a preferred implementation of a shear-based acceleration and pressure composite sensor, the lower housing has a groove at its center on the top surface. The groove has a circular cross-section and contains a diaphragm. The outer edge of the diaphragm is fixedly connected to the inner wall of the groove, and the center of the diaphragm is convex. The force transmission column is installed at the central apex of the diaphragm. The circular groove and the convex diaphragm form an integrated force transmission structure, eliminating the contact gap between the force transmission block and the diaphragm in traditional split structures. This allows external pressure to be directly and losslessly transmitted to the force transmission column. The convex diaphragm structure optimizes the stress concentration area, increases the deformation amplitude after being stressed, and centrally transmits pressure, thereby causing a more significant displacement of the force transmission column. This results in a stronger shear force on the pressure-sensitive ceramic sheet, significantly improving the detection sensitivity and response speed of minute pressure signals, making it particularly suitable for dynamic micro-pressure detection scenarios.

[0010] As a preferred implementation of a shear-based composite acceleration and pressure sensor, the height of the pressure core is less than the height of the pressure core shell. The pressure core is located inside the lower part of the pressure core shell, and the acceleration core shell is located above the pressure core shell, with a certain distance between them. This vertical arrangement and gap design effectively isolates force transmission interference between the two, preventing the displacement of the mass block during acceleration detection from affecting the pressure-sensitive element, or causing the acceleration core to generate false signals during pressure transmission, thereby improving the detection purity of both types of signals. Simultaneously, the pressure core is placed inside the lower part of the shell, and the acceleration core shell overlaps the pressure core shell, forming a compact coaxial integrated structure. This further reduces the overall size of the sensor while ensuring anti-interference performance, enhancing spatial adaptability.

[0011] As a preferred implementation of a shear-based acceleration and pressure composite sensor, the upper housing is equipped with a dual-core connector, which includes two signal pins. The acceleration core mass block is made of conductive material and is connected to one of the signal pins. A through-hole is formed in the acceleration core mass block along its vertical direction. At least one of the multiple electrode plates is connected to the other signal pin via a wire passing through the through-hole in the acceleration core mass block. The two signal pins of the dual-core connector correspond to acceleration and pressure signal outputs respectively, enabling independent transmission of the two types of signals and avoiding signal crosstalk. The conductive acceleration core mass block can directly serve as a signal transmission medium, reducing the need for additional wires and simplifying the internal structure. The through-hole in the mass block provides a concealed wiring channel for the pressure signal wire, preventing the wire from being exposed and subjected to mechanical wear or signal interference. This also makes the internal wiring neater, reduces the risk of wire tangling during assembly, and improves the reliability and signal transmission stability of the sensor.

[0012] As a preferred implementation of a shear-based acceleration and pressure composite sensor, a mode selection switch is connected to the dual-core connector. The mode selection switch includes parallel acceleration output lines and pressure output lines. An acceleration input electrode is located above the acceleration output line, and a pressure input electrode is located above the pressure output line. A toggle block is provided on each of the acceleration and pressure output lines, and the two toggle blocks are insulated and fixedly connected. A conductor post is provided on the upper surface of the toggle block. A first contact and a third contact are protruding from the side of the pressure input electrode, and a second contact and a fourth contact are protruding from the side of the acceleration input electrode. In the extension direction of the pressure output line, the first and second contacts are staggered, and the third and fourth contacts are located at the same position and face each other. When the toggle block is moved to different set positions, the conductor post on the toggle block makes contact with the corresponding contact and conducts electricity. By using a toggle switch to facilitate contact between the conductor post and different contacts, it is possible to easily switch between three modes: acceleration detection only, pressure detection only, and simultaneous acceleration and pressure detection, breaking through the limitation of the single function of traditional composite sensors. The dual toggle switch design with insulated connection ensures the independence of the two signal switching and avoids signal interference during mode switching. The staggered and aligned layout of the contacts makes the mode switching logic clear and the operation intuitive, which can quickly adapt to the detection needs of different scenarios and improve the flexibility and practicality of the sensor.

[0013] As a preferred implementation of a shear-based acceleration and pressure composite sensor, the acceleration input electrode has a fifth contact on its end side, and the pressure input electrode has a sixth contact on its end side. The mode selection switch also includes a shorting tab. When the toggle is moved to the ends of the acceleration and pressure input electrodes, the two conductor posts contact the fifth and sixth contacts respectively, and simultaneously contact the shorting tab. Through the cooperation of the fifth and sixth contacts and the shorting tab, an additional pressure detection mode with acceleration compensation is achieved. When the conductor posts simultaneously contact the corresponding contacts and the shorting tab, the acceleration signal can cancel out the acceleration interference term in the pressure signal, solving the error problem in pressure detection during vibration. This design expands the compensation function based on the original switch structure without adding extra hardware, simplifying the structural design, and significantly improving the pressure detection accuracy of the sensor in harsh vibration environments, thus expanding its applicable scenarios.

[0014] On the other hand, the present invention also provides an assembly method for a shear-based composite acceleration and pressure sensor, comprising the following steps:

[0015] S1. Attach acceleration-sensitive ceramic sheets around the periphery of the acceleration core mass block, attach the acceleration core outer shell unit to the outside of the acceleration-sensitive ceramic sheets, apply a pre-tightening force perpendicular to the side of the acceleration core mass block to the acceleration core outer shell unit, weld at the contact gaps between the acceleration core outer shell units, weld the first wire onto the acceleration core mass block, and complete the assembly of the acceleration detection module;

[0016] S2. Sequentially attach multiple sets of pressure-sensitive ceramic sheets, electrode sheets, insulating blocks, and pressure core shell units to multiple sides of the force transmission column of the lower shell, apply a pre-tightening force perpendicular to the side of the force transmission column to the pressure core shell units, weld at the contact gaps between the pressure core shell units, weld a second wire on any one of the electrode sheets, and then complete the assembly of the pressure detection module and the lower shell.

[0017] S3. Pass the second wire through the through hole in the center of the acceleration core mass block, then place the acceleration detection module above the pressure detection module, and weld it at the gap where the acceleration detection module and the pressure detection module come into contact.

[0018] S4. Solder the first wire and the second wire to the lower ends of the two signal pins in the upper housing, then place the upper housing on top of the acceleration detection module and solder at the gap where the acceleration detection module and the upper housing meet.

[0019] This method employs a modular, step-by-step assembly approach with pre-tightening welding for fixation. The acceleration and pressure detection modules are assembled independently first, then joined together as a whole, reducing the assembly difficulty of complex structures. By applying pre-tightening force perpendicular to the side and welding the seams, the pre-tightening state of sensitive components can be precisely locked, preventing pre-tightening force loss after assembly and ensuring detection accuracy. The wiring method, where wires pass through the through-holes in the mass block, along with welding fixation between modules, achieves compact integration of the internal structure and stable signal transmission. The overall process is standardized and highly operable, facilitating product consistency during mass production.

[0020] As a preferred implementation of an assembly method for a shear-based composite acceleration and pressure sensor, the method further includes:

[0021] S5. Install the mode selection switch onto the two-core connector on the upper housing, and connect the two signal pins to the acceleration input electrode and pressure input electrode of the mode selection switch, respectively.

[0022] Further installation of a mode selection switch enables the sensor to directly switch between multiple modes after the basic structure assembly is completed, eliminating the need for additional processing and simplifying the production process. The precise connection between the signal pin and the switch electrode ensures the stability of signal transmission during mode switching, preventing functional failure due to loose connections. This step seamlessly integrates structural assembly and functional integration, further improving production efficiency and the integrated performance of the product, ensuring that the sensor is ready to be used in diverse detection scenarios upon leaving the factory.

[0023] As can be seen from the above technical solutions, the advantages of this invention are as follows: This solution is based on the shearing principle. By setting a hexagonal prism acceleration core mass block and force transmission column design, combined with polygonal arrangement of sensitive ceramic plates, and pre-tightening welding fixation of trapezoidal single-unit spliced ​​shell, it not only improves the detection sensitivity by utilizing the signal superposition effect, but also ensures the stability of the pre-tightening force through the guiding nature of the trapezoidal structure and the welding locking mechanism, avoiding the problems of pre-tightening rebound and uneven force distribution in traditional structures; the force transmission structure of the integrated convex diaphragm eliminates the force transmission gap, enhancing the accuracy and response speed of micro-pressure detection; the coaxial upper and lower gap layout of the acceleration and pressure detection modules achieves miniaturization and integration while isolating force transmission interference and improving signal purity. The dual-core connector and hidden wiring design enable independent and stable transmission of two types of signals, while the mode selection switch with a shorting piece enables the sensor to have four detection modes: acceleration detection only, pressure detection only, dual-parameter synchronous detection, and pressure detection with acceleration compensation, which can be adapted to diverse scenarios, especially solving the problem of pressure detection error in vibration environments. At the assembly level, modular step-by-step assembly and pre-tightening welding processes reduce the assembly difficulty of complex structures and ensure product consistency. The integrated assembly of the mode selection switch further simplifies the production process and improves the integrated performance of the product, enabling the sensor to form comprehensive advantages in miniaturization, high precision, anti-interference, and multi-scenario adaptation. Attached Figure Description

[0024] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a cross-sectional schematic diagram of the composite sensor in a specific embodiment of the present invention.

[0026] Figure 2 This is an exploded view of the composite sensor according to a specific embodiment of the present invention.

[0027] Figure 3 This is a schematic diagram of the structure of a dual-core cable in a specific embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram of the mode selection switch in a specific embodiment of the present invention.

[0029] Explanation of main figure symbols

[0030] 01. Acceleration detection module, 02. Pressure detection module, 03. Mode selection switch, 1. Upper housing, 2. Glass sintered block, 3. Signal pin, 4. Acceleration core outer shell unit, 5. Acceleration sensitive ceramic plate, 6. Acceleration core mass block, 7. Pressure core outer shell unit, 8. Insulating block, 9. Electrode plate, 10. Pressure sensitive ceramic plate, 11. Lower housing, 12. Dual-core cable, 13. Cable metal inner sheath, 14. Cable connector pin. 15. Cable connector glass sintered base; 16. Knurled nut; 17. Force transmission column; 18. Groove; 19. Diaphragm; 20. Acceleration input electrode; 21. Pressure input electrode; 22. Acceleration output line; 23. Pressure output line; 24. Toggle block; 25. Conductor post; 26. First contact; 27. Second contact; 28. Third contact; 29. ​​Fourth contact; 30. Fifth contact; 31. Sixth contact; 32. Shorting tab; 33. Pressure sensing hole. Detailed Implementation

[0031] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0032] Example 1

[0033] like Figure 1 , 2 As shown, an acceleration and pressure composite sensor based on a shear-type structure is generally a hexagonal prism structure, including an upper housing 1 and a lower housing 11. The top surface of the upper housing 1 is provided with a dual-core connector, and the bottom surface of the lower housing 11 is provided with mounting studs for mounting itself onto the object being detected. An acceleration detection module 01 and a pressure detection module 02 are provided between the upper housing 1 and the lower housing 11.

[0034] The upper housing 1 has a through hole in the center, and two signal pins 3 are provided in the through hole. At the same time, the through hole is filled with glass powder. The glass sintering block 2 is formed by high temperature sintering and the signal pins are fixed to form a dual-core connector structure.

[0035] like Figure 2As shown, the acceleration detection module 01 includes an acceleration core and an acceleration core shell. The acceleration core includes an acceleration core mass block 6, which is a regular hexagonal prism structure. Each side of the acceleration core mass block 6 is provided with an acceleration-sensitive ceramic sheet 5. The acceleration core shell surrounds the outer periphery of the acceleration core. The acceleration-sensitive ceramic sheet 5 is pressed between the outer peripheral surface of the acceleration core mass block 6 and the inner peripheral surface of the acceleration core shell. The acceleration core mass block 6 is made of conductive material and is connected to a signal pin 3. After the sensor is installed, it moves with the detected object. The acceleration core mass block 6 remains stationary under inertia, thereby generating a shear force on the acceleration-sensitive ceramic sheet 5 and generating charge output: the vibration acceleration generates an inertial shear force through the mass block, which acts on the piezoelectric ceramic. The ceramic generates charge output through the d15 effect. The ceramic is polarized along the shear direction, and the inertial force causes the ceramic to undergo shear deformation. The formula for calculating charge sensitivity (Sa) is: Sa = d15 × m × n, where d15 is the ceramic piezoelectric coefficient, m is the mass of the mass block, and n is the number of ceramic pieces.

[0036] The pressure detection module 02 includes a pressure core and a pressure core housing. The pressure core includes a force transmission column 17, which is located at the center of the upper surface of the lower housing 11. Specifically, the top surface of the lower housing 11 has a groove 18 at its center, which connects to a pressure sensing hole 33 at the center of the bottom surface of the lower housing 11. The groove 18 has a circular cross-section and contains a diaphragm 19. The outer edge of the diaphragm 19 is fixedly connected to the inner wall of the groove 18. The center of the diaphragm 19 protrudes upwards, and the force transmission column 17 is installed at the center apex of the diaphragm 19. 7 is a regular hexagonal prism structure. Each side of the force transmission column 17 is provided with a pressure-sensitive ceramic plate 10, an electrode plate 9, and an insulating block 8 arranged sequentially from the inside to the outside. The edges of adjacent electrode plates 9 are in contact with each other. The pressure-sensitive ceramic plate 10, the electrode plate 9, and the insulating block 8 are pressed between the outer peripheral surface of the force transmission column 17 and the inner peripheral surface of the pressure core shell. The acceleration core mass block 6 has through holes in the vertical direction. Among the multiple electrode plates 9, at least one electrode plate 9 is connected to another signal pin 3 through a wire, which passes through the through hole in the acceleration core mass block 6. In this way, when subjected to pressure, the diaphragm structure can generate a large deformation, pushing the force transmission column 17 located at its center to generate displacement, thereby generating shear force on the ceramic surface and generating charge output: the measured pressure is converted into shear force through the diaphragm, acts on the piezoelectric ceramic, and then outputs charge through the d15 effect. The formula for calculating charge sensitivity (Sa) is Sa=d15×k×A×n, where d15 is the ceramic piezoelectric coefficient, k is the pressure-shear force conversion coefficient, A is the ceramic force-bearing area, and n is the number of ceramic pieces.

[0037] Furthermore, in traditional pressure or shear sensors, the preload of the core comes from applying pressure to the outside of the housing after sensor assembly, causing the housing to shrink and deform. After the external pressure is removed, the housing will rebound to a certain extent, resulting in a reduction in the actual preload and making it difficult to control accurately. To address this, in this solution, the acceleration core housing and the pressure core housing adopt a separate structure:

[0038] As shown in the figure, adapted to the internal hexagonal prism core structure, the accelerometer core shell includes six accelerometer core shell units 4. Each accelerometer core shell unit 4 is located outside the six acceleration-sensitive ceramic plates 5. Each accelerometer core shell unit 4 is a quadrangular prism structure with an isosceles trapezoidal cross-section, and the two base angles of the trapezoid are 60°. The sides of the corresponding trapezoidal sides of the multiple accelerometer core shell units 4 are sequentially abutted. The acceleration-sensitive ceramic plates 5 are pressed between the accelerometer core mass block 6 and the sides of the corresponding trapezoidal short base of the corresponding accelerometer core shell unit 4. During assembly, the six accelerometer core shell units 4 are assembled with the central accelerometer core, and the accelerometer core shell units are then aligned using external clamps or other fixtures. The body 4 is pressurized, and after pressurization, the six acceleration core shell units 4 are welded and fixed at the joint. The method of pressing first and then welding avoids the springback problem of traditional diameter reduction pressurization and ensures the stability of the preload. Similarly, the pressure core shell includes six pressure core shell units 7. The pressure core shell units 7 are located outside the insulating block 8. The pressure core shell units 7 are quadrangular prism structures with an isosceles trapezoidal cross-section and a base angle of 60°. The sides of the corresponding trapezoidal two sides of the multiple pressure core shell units 7 are sequentially attached and fixedly connected. The pressure sensitive ceramic plate 10, the electrode plate 9 and the insulating block 8 are pressed between the outer peripheral surface of the force transmission column 17 and the side of the corresponding trapezoidal short base of the pressure core shell unit 7. Furthermore, the height of the pressure core is less than the height of the pressure core shell, the pressure core is located on the lower inner side of the pressure core shell, the acceleration core shell is located above the pressure core shell, and there is a certain distance between the pressure core and the acceleration core.

[0039] This composite sensor can be used as follows: Figure 3The dual-core cable 12 shown enables signal transmission. The lower end of the dual-core cable 12 is provided with a metal inner sleeve 13. Inside the metal inner sleeve 13 is a cable connector glass sintered seat 15. Two cable connector pins 14 are sintered and fixed in the cable connector glass sintered seat 15. A knurled nut 16 is provided on the outside of the cable connector glass sintered seat 15. The knurled nut 16 can rotate relative to the cable connector glass sintered seat 15. During installation, the cable connector glass sintered seat 15 is inserted into the dual-core connector of the composite sensor. The two cable connector pins 14 are respectively connected to the two signal pins 3. Then, the knurled nut 16 is screwed onto the top stud of the upper housing 1.

[0040] Furthermore, a mode selection switch 03 can be installed on the two-core connector or the two-core cable 12, such as... Figure 4 As shown, the mode selection switch includes an acceleration output line 22 and a pressure output line 23 arranged in parallel. An acceleration input electrode 20 is located above the acceleration output line 22, and a pressure input electrode 21 is located above the pressure output line 23. A toggle block 24 is provided on both the acceleration output line 22 and the pressure output line 23, and the two toggle blocks 24 are insulated and fixedly connected. A conductor post 25 is provided on the upper surface of each toggle block 24. A first contact 26 and a third contact 28 protrude from the side of the pressure input electrode 21, and a second contact 27 and a fourth contact 29 protrude from the side of the acceleration input electrode 20. In the extending direction of the pressure output line 23, the first contact 26 and... The second contact 27 is offset, and the third contact 28 and the fourth contact 29 are located in the same position and face each other. When the toggle block 24 is moved to different set positions, the conductor post 25 on the toggle block 24 makes contact with the corresponding contact. The end side of the acceleration input electrode 20 is also provided with a fifth contact 30, and the end side of the pressure input electrode 21 is also provided with a sixth contact 31. The mode selection switch 03 is also provided with a shorting piece 32. When the toggle block 24 is moved to the end of the acceleration input electrode 20 and the pressure input electrode 21, the two conductor posts 25 make contact with the fifth contact 30 and the sixth contact 31 respectively, and simultaneously make contact with the shorting piece 32.

[0041] Based on the mode selection switch, this composite sensor has four output modes:

[0042] Individual pressure signal output: When the toggle 24 is moved to the position of the first contact 26, one of the conductor posts 25 is in contact with the first contact, and the other conductor post is not in contact with any contact. At this time, the pressure input electrode 21 is connected to the pressure output line 23, and the composite sensor outputs a pressure signal.

[0043] Individual acceleration output: Move the toggle 24 to the position of the second contact 27, one of the conductor posts 25 contacts the second contact 27, the acceleration input electrode 20 is connected to the acceleration output line, and the composite sensor outputs an acceleration signal;

[0044] Simultaneous output of acceleration and pressure: When the toggle 24 is moved to the position of the third contact 28 and the fourth contact 29, one conductor post 25 is in contact with the third contact 28, the pressure input electrode 21 is connected to the pressure output line 23, the other conductor post 25 is in contact with the fourth contact 29, the acceleration input electrode 20 is connected to the acceleration output line 22, and the composite sensor outputs acceleration and pressure signals;

[0045] Pressure sensor signal output with compensation function: When the toggle 24 is moved to the positions of the fifth contact 30 and the sixth contact 31, the two conductor posts are in contact with the fifth contact 30 and the sixth contact 31 respectively. At the same time, the two ends of the shorting piece 32 are in contact with the two conductor posts respectively. At this time, the acceleration input electrode 20 and the pressure input electrode 21 are shorted, and the acceleration noise in the acceleration signal and the pressure signal cancel each other out. The total pressure output signal is composed of the superposition of the "target pressure contribution" and the "interference acceleration contribution". The essence of compensation is to separate and cancel the interference term of acceleration, and finally extract the true signal that is only related to pressure. The core formula is Q. p =Q T -Q a Q p Q represents the actual signal charge of the pressure sensor. T Q represents the total output charge. a By providing the output charge of the accelerometer, the composite sensor can output a pressure signal with acceleration compensation. This solves the problem that the additional deformation of the piezoelectric material caused by acceleration (inertial force interference) is misinterpreted as a pressure signal when there is vibration / impact in the measurement environment. It enables accurate pressure measurement in vibration / impact scenarios, and is especially suitable for scenarios where "pressure is the core measurement target, but environmental acceleration interference is unavoidable". For example, there is continuous vibration in areas such as the engine compartment and chassis of a car. The high-frequency vibration (100-1000Hz) when the engine is running will cause ordinary sensors to output "pressure fluctuation illusions". Ordinary piezoelectric pressure sensors are easily affected by acceleration interference, which leads to pressure measurement deviation. However, the model with acceleration compensation can accurately capture the real pressure. After acceleration compensation, vibration interference can be corrected in real time to ensure the accuracy of fuel rail pressure measurement.

[0046] Example 2

[0047] This embodiment further provides an assembly method for an acceleration and pressure composite sensor based on a shear structure, including the following steps:

[0048] S1. Attach acceleration-sensitive ceramic sheets 5 around the acceleration core mass block 6, attach acceleration core outer shell unit 4 to the outside of the acceleration-sensitive ceramic sheets 5, apply a pre-tightening force perpendicular to the side of the acceleration core mass block 6 to the acceleration core outer shell unit 4, weld at the contact gap of the acceleration core outer shell unit 4, weld the first wire on the acceleration core mass block 6, and complete the assembly of the acceleration detection module 01;

[0049] S2. Multiple sets of pressure-sensitive ceramic sheets 10, electrode sheets 9, insulating blocks 8, and pressure core shell units 7 are sequentially attached to multiple sides of the force transmission column 17 of the lower shell 11, and a pre-tightening force perpendicular to the side of the force transmission column 17 is applied to the pressure core shell units 7. Welding is performed at the contact gaps of the pressure core shell units 7. A second wire is welded on any one of the electrode sheets 9 to complete the assembly of the pressure detection module 02 and the lower shell 11.

[0050] S3. Pass the second wire through the through hole in the center of the acceleration core mass block 6, and then place the acceleration detection module 01 above the pressure detection module 02, and weld it at the gap where the acceleration detection module 01 and the pressure detection module 02 come into contact.

[0051] S4. Solder the first wire and the second wire to the lower ends of the two signal pins 3 in the upper housing 1 respectively, and then place the upper housing 1 above the acceleration detection module 01, and solder at the gap where the acceleration detection module 01 and the upper housing 1 meet.

[0052] S5. Install the mode selection switch 03 onto the dual-core connector of the upper housing 1, and connect the two signal pins 3 to the acceleration input electrode 20 and the pressure input electrode 21 of the mode selection switch 03 respectively; or, install the dual-core cable 12 onto the dual-core connector.

[0053] As can be seen from the above technical solutions, the beneficial effects of the present invention are as follows:

[0054] 1. Overall structural design: This composite sensor adopts a shear-type piezoelectric structure, achieving miniaturization. In traditional monitoring scenarios, acceleration and pressure need to be collected separately by an "accelerometer" and a "pressure sensor". However, this composite sensor can synchronously output acceleration and pressure signals in the same spatiotemporal dimension through an integrated dual detection module. This not only reduces the number of components and installation steps, but also avoids the "time difference" between multiple components. In addition, the overall design height of this sensor can be less than 15mm and the installation diameter can be less than 7.5mm. The miniaturized structural design enables it to achieve multi-dimensional breakthroughs in "space adaptability, performance optimization, and scenario expansion". It can not only solve the application limitations of traditional large-size components, but also significantly improve its own inherent frequency through the miniaturized structural design, covering higher frequency dynamic signals.

[0055] 2. Shear Structure Design: Piezoelectric pressure sensors generally use compression sensing elements. To improve the sensor's charge sensitivity, the only way is to increase the force-bearing area of ​​the piezoelectric ceramic and the number of stacked sensing ceramic sheets. This often contradicts the initial goal of miniaturization. Shear-type piezoelectric pressure sensor design solves this problem. The sensitivity of the shear sensing element is determined solely by the shear piezoelectric coefficient (d15, higher than that of compression structures) and the structural dimensions. Therefore, the designed shear-type pressure sensor uses a hexagonal mounting surface, increasing the size of the force-bearing structure, thus enabling the miniaturized sensor to output a sensitivity >20000 pC / MPa. Higher sensitivity means a larger piezoelectric charge generated under the same pressure change, making it easier for subsequent signal conditioning circuits to recognize. 20000 pC / MPa is considered high sensitivity, and its core value lies in solving the problem of measuring low pressures and minute pressure fluctuations, such as 0.05 MPa.

[0056] 3. Housing Design and Pre-tightening Mechanism: Traditional piezoelectric sensors often have an integral outer shell for sealing the sensor and protecting the internal core. In terms of the core pre-tightening mechanism, a pressure pre-tightening mechanism is used, which is prone to pressure leakage and springback problems. Therefore, this composite sensor designs the housing as a six-part trapezoidal structure. After interlocking, the internal core can be pre-tightened in pairs. After welding, the pre-tightening force can be maintained, thereby improving the stiffness of the sensor's elastic system.

[0057] 4. Pressure detection module diaphragm structure design: Pressure can be directly and losslessly transmitted from the lower shell of this structure to the sensitive area of ​​the ceramic. In addition, the concave structure of the diaphragm can use the "convex structure" to change the stress concentration area and deformation trajectory of the diaphragm after being subjected to force, thereby increasing the force accuracy of the sensor.

[0058] 5. Multi-mode output function design: Traditional piezoelectric sensors often have limited functions and application scenarios. This composite sensor outputs acceleration and pressure signals separately through a dual-core cable, and the adapter module is equipped with a toggle switch, which can realize multi-mode output function, enabling it to monitor only acceleration signals, only pressure signals, simultaneously monitor acceleration and pressure signals, and monitor pressure signals with acceleration compensation function.

[0059] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A shear-based acceleration and pressure composite sensor, characterized in that, The system includes an upper housing (1) and a lower housing (11). An acceleration detection module (01) and a pressure detection module (02) are provided between the upper housing (1) and the lower housing (11). The acceleration detection module (01) and the pressure detection module (02) are arranged coaxially vertically. The upper housing (1) is provided with a dual-core connector. The acceleration detection module (01) includes an acceleration core and an acceleration core shell. The acceleration core includes an acceleration core mass block (6), which is a regular polygonal prism structure. Each side of the acceleration core mass block (6) is provided with an acceleration-sensitive ceramic sheet (5). The acceleration core shell surrounds the outer periphery of the acceleration core, and the acceleration-sensitive ceramic sheet (5) is pressed between the outer peripheral surface of the acceleration core mass block (6) and the inner peripheral surface of the acceleration core shell. The pressure detection module (02) includes a pressure core and a pressure core shell. The pressure core includes a force transmission column (17), which is located at the center of the upper surface of the lower shell (11). The force transmission column (17) is a regular polygonal prism structure. Each side of the force transmission column (17) is provided with a pressure-sensitive ceramic sheet (10), an electrode sheet (9), and an insulating block (8) from the inside out. The edges of adjacent electrode sheets (9) are in contact with each other. The pressure-sensitive ceramic sheet (10) and the electrode sheet... (9) and the insulating block (8) are pressed between the outer peripheral surface of the force transmission column (17) and the inner peripheral surface of the pressure core shell; the top surface of the lower shell (11) is provided with a groove (18), the cross-section of the groove (18) is circular, a diaphragm (19) is provided in the groove (18), the outer edge of the diaphragm (19) is fixedly connected to the inner sidewall of the groove (18), the center position of the diaphragm (19) is convex, and the force transmission column (17) is installed at the center vertex of the diaphragm (19).

2. The shear-based acceleration and pressure composite sensor according to claim 1, characterized in that, The accelerometer core shell includes multiple accelerometer core shell units (4). The accelerometer core shell units (4) are located outside the accelerometer-sensitive ceramic sheet (5). The accelerometer core shell units (4) are quadrangular prism structures with trapezoidal cross-sections. The sides of the corresponding trapezoidal waists of the multiple accelerometer core shell units (4) are sequentially abutted and fixedly connected. The accelerometer-sensitive ceramic sheet (5) is pressed between the accelerometer core mass block (6) and the side of the corresponding trapezoidal short base of the corresponding accelerometer core shell unit (4). The pressure core shell includes multiple pressure core shell units (7). The pressure core shell units (7) are located outside the insulating block (8). The pressure core shell units (7) are quadrangular prism structures with trapezoidal cross-sections. The sides of the corresponding trapezoidal waists of the multiple pressure core shell units (7) are sequentially attached and fixedly connected. The pressure-sensitive ceramic sheet (10), the electrode sheet (9), and the insulating block (8) are pressed between the outer peripheral surface of the force transmission column (17) and the side of the corresponding trapezoidal short base of the pressure core shell unit (7).

3. The shear-based acceleration and pressure composite sensor according to claim 2, characterized in that, The acceleration core mass block (6) and the force transmission column (17) are both regular hexagonal prisms; the cross-sections of the acceleration core shell unit (4) and the pressure core shell unit (7) are both isosceles trapezoids, and the base angle of the isosceles trapezoid is 60 degrees.

4. The shear-based acceleration and pressure composite sensor according to claim 1, characterized in that, The height of the pressure core is less than the height of the pressure core shell. The pressure core is located on the lower inner side of the pressure core shell, and the acceleration core shell is located above the pressure core shell. There is a certain distance between the pressure core and the acceleration core.

5. The shear-based acceleration and pressure composite sensor according to claim 1, characterized in that, The dual-core connector includes two signal pins (3). The acceleration core mass block (6) is made of conductive material and is connected to one of the signal pins (3). The acceleration core mass block (6) has a through hole in the vertical direction. Among the multiple electrode plates (9), at least one of the electrode plates (9) is connected to another signal pin (3) through a wire. The wire passes through the through hole in the acceleration core mass block (6).

6. The shear-based acceleration and pressure composite sensor according to claim 5, characterized in that, A mode selection switch (03) is connected to the dual-core connector. The mode selection switch includes an acceleration output line (22) and a pressure output line (23) arranged in parallel. An acceleration input electrode (20) is provided above the acceleration output line (22), and a pressure input electrode (21) is provided above the pressure output line (23). A toggle block (24) is provided on the acceleration output line (22) and the pressure output line (23) respectively. The two toggle blocks (24) are insulated and fixedly connected. A conductor post (25) is provided on the upper surface of the toggle block (24). The pressure input electrode... The side of the (21) protrudes with a first contact (26) and a third contact (28), and the side of the acceleration input electrode (20) protrudes with a second contact (27) and a fourth contact (29). In the extension direction of the pressure output line (23), the first contact (26) and the second contact (27) are staggered, and the third contact (28) and the fourth contact (29) are located at the same position and are facing each other. When the toggle block (24) is toggled to different set positions, the conductor post (25) on the toggle block (24) contacts and conducts with the corresponding contact.

7. The shear-based acceleration and pressure composite sensor according to claim 6, characterized in that, The acceleration input electrode (20) is provided with a fifth contact (30) on its end side, and the pressure input electrode (21) is provided with a sixth contact (31) on its end side. The mode selection switch (03) is also provided with a shorting piece (32). When the toggle block (24) is moved to the ends of the acceleration input electrode (20) and the pressure input electrode (21), the two conductor posts (25) contact the fifth contact (30) and the sixth contact (31) respectively, and simultaneously contact the shorting piece (32).

8. An assembly method for a shear-based composite acceleration and pressure sensor, characterized in that, Includes the following steps: S1. Attach acceleration-sensitive ceramic sheets (5) around the acceleration core mass block (6), attach acceleration core shell unit (4) to the outside of the acceleration-sensitive ceramic sheets (5), apply a pre-tightening force perpendicular to the side of the acceleration core mass block (6) to the acceleration core shell unit (4), weld at the gap where the acceleration core shell unit (4) contacts, weld the first wire on the acceleration core mass block (6), and complete the assembly of the acceleration detection module (01); S2. Multiple sets of pressure-sensitive ceramic sheets (10), electrode sheets (9), insulating blocks (8) and pressure core shell units (7) are sequentially pasted onto multiple sides of the force transmission column (17) of the lower shell (11), and a pre-tightening force perpendicular to the side of the force transmission column (17) is applied to the pressure core shell units (7). Welding is performed at the contact gaps of the pressure core shell units (7). A second wire is welded onto any one of the electrode sheets (9). The assembly of the pressure detection module (02) and the lower shell (11) is then completed. S3. Pass the second wire through the through hole in the center of the acceleration core mass block (6), and then place the acceleration detection module (01) above the pressure detection module (02) and weld it at the gap where the acceleration detection module (01) and the pressure detection module (02) come into contact. S4. Solder the first wire and the second wire to the lower end of the two signal pins (3) in the upper housing (1), then place the upper housing (1) above the acceleration detection module (01) and solder at the gap where the acceleration detection module (01) and the upper housing (1) meet.

9. The assembly method of the shear-based acceleration and pressure composite sensor according to claim 8, characterized in that, Also includes: S5. Install the mode selection switch (03) onto the dual-core connector of the upper housing (1), and connect the two signal pins (3) to the acceleration input electrode (20) and pressure input electrode (21) of the mode selection switch (03) respectively.

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