Shear-based acceleration and pressure composite sensor and assembly method thereof

Abstract

The invention relates to a shear-based acceleration and pressure composite sensor and an assembly method thereof, and belongs to the field of composite sensors. According to the technical scheme of the acceleration and pressure composite sensor based on the shear type structure, an acceleration detection module comprises a mass block of a regular polygon prism structure, and each side face of the mass block is provided with an acceleration sensitive ceramic piece; the pressure detection module comprises a force transmission column of a regular polygon prism structure, and each side face of the force transmission column is provided with a pressure sensitive ceramic piece, an electrode piece and an insulation block. According to the scheme, the sensitive elements of the acceleration sensor and the pressure sensor core are arranged in a polygonal mode to form a spatial three-dimensional structure, the effective area of the sensitive elements in unit volume is increased, the multiple sensitive elements act together to form superposition of pressure signals, the detection precision and sensitivity of the two are guaranteed, and the detection precision is improved. Therefore, the overall size of the composite sensor is greatly reduced on the premise that the original precision is maintained, and the composite sensor is miniaturized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of composite sensors, in particular to a shear-based acceleration and pressure composite sensor and an assembling method thereof. BACKGROUND

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

[0003] However, traditional piezoelectric sensors are limited by the structure design of stacked sensitive units, and there is a contradiction between volume and functional integration: on the one hand, if the sensitivity needs to be improved, the area of piezoelectric ceramics needs to be increased, and the corresponding electrode sheet, mass block, insulating sheet and sensor shell also need to be increased, thereby increasing the overall volume of the sensor; on the other hand, the number of independent sensors is greatly increased, and if acceleration and pressure parameters need to be monitored simultaneously, the conventional solution must use a combination of independent acceleration sensors and independent pressure sensors for installation, and due to the overall volume, it is usually difficult to install in the same position, resulting in differences in the acquisition timing of multiple sensors, which in turn leads to poor signal synchronization, making it difficult to meet the scene requirements for collaborative analysis of multiple physical quantities, and also increasing the complexity of installation operations.

[0004] The sensitive element of the shear sensor has a natural advantage in improving sensitivity due to the shear effect, with a piezoelectric coefficient much higher than that of the compression structure. However, the structure design of existing shear sensors is still not perfect, and they are still independent sensors, which still need to use the traditional arrangement mode of multiple independent sensors for installation, making it difficult to adapt to the monitoring scene requirements of miniaturization and high precision. SUMMARY

[0005] The present application provides a shear-based acceleration and pressure composite sensor that greatly reduces the volume while ensuring sensitivity, to solve the problem of large volume of independent installation and composite structure of current pressure and acceleration sensors.

[0006] To solve the above problems, the technical scheme adopted by the present application is a shear type acceleration and pressure composite sensor, comprising an upper shell and a lower shell, an acceleration detection module and a pressure detection module are arranged between the upper shell and the lower shell; the acceleration detection module comprises an acceleration core and an acceleration core shell, the acceleration core comprises an acceleration mass block, the acceleration mass block is a regular polygonal prism structure, and an acceleration sensitive ceramic sheet is arranged on each side surface of the acceleration mass block; the acceleration core shell surrounds the outer periphery of the acceleration core, and the acceleration sensitive ceramic sheet is compressed between the outer peripheral surface of the acceleration mass block and the inner peripheral surface of the acceleration core shell; the pressure detection module comprises a pressure core and a pressure core shell, the pressure core comprises a force transmission column, the force transmission column is arranged at the center position of the upper surface of the lower shell, the force transmission column is a regular polygonal prism structure, a pressure sensitive ceramic sheet, an electrode sheet and an insulating block are sequentially arranged from the inside to the outside on each side surface of the force transmission column, the edges of adjacent electrode sheets contact each other, and the pressure sensitive ceramic sheet, the electrode sheet and the insulating block are compressed between the outer peripheral surface of the force transmission column and the inner peripheral surface of the pressure core shell. The present scheme is based on shear type, and provides a new structure of acceleration and pressure composite sensor, the sensitive elements of the acceleration sensor and the pressure sensor core are arranged in a polygonal shape, forming a spatial three-dimensional structure, which improves the effective area of the sensitive elements in a unit volume, in the acceleration detection module, the mass block is used as the output, and each acceleration sensitive ceramic sheet attached to the outer periphery thereof forms the superposition of acceleration signals, in the pressure detection module, the force transmission column drives each pressure sensitive ceramic sheet, multiple electrode sheets contact each other, and the superposition of pressure signals is formed, which ensures the detection accuracy and sensitivity of the two, and further makes the composite sensor greatly reduce the overall volume on the premise of maintaining the original accuracy, so that the composite sensor can be miniaturized and arranged and used in a small space; meanwhile, the acceleration detection module and the pressure detection module are arranged coaxially and downward, the shear direction is unified, the synchronism of the two signals is improved, and more real data support can be provided for multi-physical quantity analysis.

[0007] As a preferred implementation scheme of the acceleration and pressure composite sensor based on the shear type, the acceleration core shell includes a plurality of acceleration core shell monomers located outside the acceleration sensitive ceramic sheet, the acceleration core shell monomers are quadrangular prisms with trapezoidal cross sections, the sides of the corresponding two waists of the plurality of acceleration core shell monomers are sequentially attached and fixedly connected, and the acceleration sensitive ceramic sheet is compressed between the acceleration core mass and the side of the corresponding trapezoidal short base of the corresponding acceleration core shell monomer; the pressure core shell includes a plurality of pressure core shell monomers located outside the insulating block, the pressure core shell monomers are quadrangular prisms with trapezoidal cross sections, the sides of the corresponding two waists of the plurality of pressure core shell monomers are sequentially attached and fixedly connected, and the pressure sensitive ceramic sheet, the electrode sheet and the insulating block are compressed between the outer circumferential surface of the force transmission column and the side of the corresponding trapezoidal short base of the corresponding pressure core shell monomer. The shell is divided into a plurality of monomers with trapezoidal structures, the complete shell is formed by the attachment and connection of the trapezoidal sides, the trapezoidal structure can guide the application of uniform and stable pre-tightening force to the internal sensitive elements, the problem of difficult accurate pre-tightening of the traditional integral shell is avoided, the pre-tightening force is applied to the shell monomers by the external clamp, the clamp is welded after clamping, the rebound phenomenon after the traditional diameter reduction type pressurization is avoided, the pre-tightening force is stable, the detection accuracy is ensured; at the same time, the monomer design facilitates the separate installation and adjustment of the sensitive elements on different sides, reduces the assembly difficulty, and the pre-tightening force can be maintained for a long time after welding and fixation, the stiffness and structural stability of the elastic system of the sensor are improved, and the long-term reliability of the detection accuracy is further ensured.

[0008] As a preferred implementation scheme of the acceleration and pressure composite sensor based on the shear type, the acceleration core mass and the force transmission column are regular hexagonal prisms; the cross sections of the acceleration core shell monomers and the pressure core shell monomers are isosceles trapezoids, and the base angles of the isosceles trapezoids are 60 degrees. The regular hexagonal prism structure can provide six uniformly distributed mounting surfaces, more sensitive ceramic sheets can be arranged under the same volume, and the signal superposition effect and detection sensitivity are further improved; the isosceles trapezoidal shell monomers with a base angle of 60 degrees are matched with the sides of the regular hexagonal prism, and a regular hexagonal shell can be formed after splicing, ensuring that the pre-tightening force of each sensitive element is consistent, and avoiding detection errors caused by uneven stress; in addition, the regular hexagonal structure has excellent force transmission characteristics and structural stability, can reduce the influence of external force impact on the internal core, and is suitable for detection requirements in harsh working conditions.

[0009] As a preferred implementation scheme of the acceleration and pressure composite sensor based on the shear type, the top surface of the lower shell is provided with a groove, the cross section of the groove is circular, a diaphragm is arranged in the groove, the outer edge of the diaphragm is fixedly connected with the inner side wall of the groove, the center position of the diaphragm is convex, and the force transmission column is installed at the center vertex of the diaphragm. The circular groove and the diaphragm with the convex center form an integrated force transmission structure, which eliminates the contact gap between the traditional split structure and the diaphragm, so that the external pressure can be directly and losslessly transmitted to the force transmission column; the convex diaphragm structure can optimize the stress concentration area, increase the deformation amplitude after stress, and centrally transmit the pressure, thereby driving the force transmission column to produce more obvious displacement, so that the pressure sensitive ceramic sheet can obtain stronger shear force, and the detection sensitivity and response speed of the micro pressure signal are significantly improved, which is especially suitable for dynamic micro pressure detection scenes.

[0010] As a preferred implementation scheme of the acceleration and pressure composite sensor based on the shear type, the height of the pressure core is less than the height of the pressure core shell, the pressure core is located at the lower part of the inner side of the pressure core shell, the acceleration core shell is located above the pressure core shell, and the pressure core and the acceleration core are spaced apart by a distance. The up-down layout and gap design of the pressure core and the acceleration core can effectively isolate the force transmission interference between the two, avoid the influence of the displacement of the mass block on the pressure sensitive element during acceleration detection, or avoid the generation of false signals of the acceleration core during pressure transmission, thereby improving the detection purity of the two types of signals; at the same time, the pressure core is built-in at the lower part of the shell, and the acceleration core shell is overlapped on the upper part of the pressure core shell, forming a compact coaxial integrated structure, which further compresses the overall volume of the sensor under the premise of ensuring the anti-interference performance, and enhances the space adaptability.

[0011] As a preferred implementation scheme of the acceleration and pressure composite sensor based on the shear type, the upper shell is provided with a double-core connector, the double-core connector includes two signal pins, the acceleration core mass block is made of conductive material and connected with one signal pin, the acceleration core mass block is provided with a through hole in the up-down direction, at least one of the plurality of electrode sheets is connected to the other signal pin through a wire, and the wire passes through the through hole in the acceleration core mass block. The two signal pins of the double-core connector correspond to the acceleration and pressure signal outputs respectively, realizing independent transmission of the two types of signals and avoiding signal crosstalk; the acceleration core mass block made of conductive material can be directly used as a signal transmission medium, reducing the arrangement of additional wires and simplifying the internal structure; the through hole in the mass block provides a hidden wiring channel for the pressure signal wire, avoiding mechanical wear or signal interference of the exposed wire, while making the internal wiring more tidy, reducing the risk of wire entanglement in the assembly process, and improving the reliability and signal transmission stability of the sensor.

[0012] As a preferred implementation scheme of the acceleration and pressure composite sensor based on the shear type, the double-core connector is provided with a mode selection switch, the mode selection switch comprises an acceleration output line and a pressure output line arranged in parallel, an acceleration input electrode is arranged above the acceleration output line, a pressure input electrode is arranged above the pressure output line, a dial block is arranged on the acceleration output line and the pressure output line respectively, the two dial blocks are fixedly connected in insulation, a conductor column is arranged on the upper surface of the dial block, a first contact and a third contact are protrusively arranged on the side surface of the pressure input electrode, a second contact and a fourth contact are protrusively arranged on the side surface of the acceleration input electrode, the first contact and the second contact are arranged in a staggered manner in the extension direction of the pressure output line, the third contact and the fourth contact are located at the same position and are arranged in a face-to-face manner, and the conductor column on the dial block is in contact with the corresponding contact when the dial block is dialled to different set positions. The contact combination of the dial block and the conductor column with different contacts can conveniently realize the switching of three modes of only acceleration detection, only pressure detection and acceleration and pressure detection at the same time, and break through the limitation of single function of the traditional composite sensor. The design of the two dial blocks in insulation connection can guarantee the independence of the switching of the two signals and avoid signal interference during mode switching. The staggered and face-to-face layout of the contacts makes the mode switching logic clear and the operation intuitive, and the detection requirements of different scenes can be quickly adapted, thereby improving the flexibility and practicality of the sensor.

[0013] As a preferred implementation scheme of the acceleration and pressure composite sensor based on the shear type, the end side of the acceleration input electrode is further provided with a fifth contact, the end side of the pressure input electrode is further provided with a sixth contact, and a shorting sheet is further arranged in the mode selection switch; when the dial block is dialled to the end of the acceleration input electrode and the pressure input electrode, the two conductor columns are in contact with the fifth contact and the sixth contact respectively and are in contact with the shorting sheet at the same time. Through the cooperation of the fifth contact, the sixth contact and the shorting sheet, an additional pressure detection mode with acceleration compensation is realized, when the conductor columns simultaneously contact the corresponding contacts and the shorting sheet, the acceleration signal can cancel out the acceleration interference term in the pressure signal, thereby solving the error problem of pressure detection in a vibration scene; the design expands the compensation function on the basis of the original switch structure, does not need to increase additional hardware, simplifies the structure design, and greatly improves the pressure detection precision of the sensor in a severe vibration environment, thereby expanding the applicable scene.

[0014] In another aspect, the application further provides an assembly method of an acceleration and pressure composite sensor based on the shear type, comprising the following steps: S1. Paste acceleration sensitive ceramic sheets on the periphery of the acceleration core mass block respectively, paste acceleration core shell monomers on the outside of the acceleration sensitive ceramic sheets, apply a pre-tightening force perpendicular to the side surface of the acceleration core mass block to the acceleration core shell monomers, weld at the gap where the acceleration core shell monomers contact, weld the first lead wire on the acceleration core mass block, and complete the assembly of the acceleration detection module; S2. Paste multiple sets of pressure sensitive ceramic sheets, electrode sheets, insulating blocks, and pressure core shell monomers to the multiple side surfaces of the force transmission column of the lower shell in turn respectively, and apply a pre-tightening force perpendicular to the side surface of the force transmission column to the pressure core shell monomers, weld at the gap where the pressure core shell monomers contact, weld the second lead wire on any one of the electrode sheets, and then complete the assembly of the pressure detection module and the lower shell; S3. Pass the second lead 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 at the gap where the acceleration detection module and the pressure detection module contact; S4. Weld the first lead wire and the second lead wire to the lower ends of the two signal pins in the upper shell respectively, then place the upper shell above the acceleration detection module, and weld at the gap where the acceleration detection module and the upper shell contact.

[0015] The method adopts modularized step-by-step assembly and pre-tightening and welding fixation ideas, first completes independent assembly of the acceleration and pressure detection modules respectively, and then performs overall splicing, which reduces the assembly difficulty of complex structures; through pre-tightening force application and gap welding perpendicular to the side surface, the pre-tightening state of the sensitive element can be accurately locked, the pre-tightening force loss after assembly is avoided, and the detection accuracy is guaranteed; the wiring mode of the lead wire passing through the through hole in the mass block and the welding fixation between the modules realize compact integration of the internal structure and stable transmission of the signal, the overall process is standardized and has strong operability, which is conducive to ensuring product consistency during batch production.

[0016] As a preferred implementation scheme of the assembly method of the shear type acceleration and pressure composite sensor, the method further comprises: S5. Install the mode selection switch on the double-core connector of the upper shell, and connect the two signal pins with the acceleration input electrode and the pressure input electrode of the mode selection switch respectively.

[0017] Further installation of the mode selection switch enables the sensor to directly have multi-mode switching function after completion of the basic structure assembly, without additional subsequent processing, which simplifies the production process; accurate connection of the signal pins and the switch electrodes guarantees the stability of signal conduction during mode switching, avoiding functional failure caused by loose connection; this step seamlessly connects structure assembly and function integration, further improves production efficiency and product integration performance, and ensures that the sensor can be adapted to multiple detection scenes when leaving the factory.

[0018] It can be seen from the above technical solution that the advantages of the present application are: the present scheme is based on the shearing principle, through the design of the acceleration core mass block of the regular hexagonal prism and the force transmission column, matched with the sensitive ceramic sheet arranged in a polygon, combined with the pre-tightening welding fixation of the trapezoidal single body splicing shell, the detection sensitivity is improved by means of signal superposition effect, and the pre-tightening force stability is ensured through the guiding property of the trapezoidal structure and the welding locking mechanism, avoiding the problems of pre-tightening rebound and uneven stress of the traditional structure; the force transmission structure of the integrated convex diaphragm eliminates the force transmission gap, and enhances the accuracy and response speed of the micro pressure detection; the coaxial upper and lower gap layout of the acceleration and pressure detection modules not only realizes miniaturization integration, but also isolates the force transmission interference, and improves the signal purity. The double-core connector and the hidden wiring design realize independent and stable transmission of two types of signals, and the mode selection switch with a short piece makes the sensor have four detection modes of only acceleration detection, only pressure detection, double parameter synchronous detection and pressure detection with acceleration compensation, which can adapt to multiple scenes, especially solving the problem of pressure detection error in a vibrating environment. In the assembly level, the modular step-by-step assembly and pre-tightening welding process reduces the assembly difficulty of complex structures, ensures the product consistency, and the integrated assembly of the mode selection switch further simplifies the production process, improves the integrated performance of the product, and makes the sensor form a comprehensive advantage in miniaturization, high precision, anti-interference and multi-scene adaptation. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the present application, the drawings needed to be used in the description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 It is a sectional view of the composite sensor in the specific embodiment of the present application.

[0021] Figure 2 It is an exploded view of the composite sensor in the specific embodiment of the present application.

[0022] Figure 3 It is a structure schematic view of the double-core cable in the specific embodiment of the present application.

[0023] Figure 4 It is a structure schematic view of the mode selection switch in the specific embodiment of the present application.

[0024] MAIN REFERENCE NUMERALS 01. acceleration detection module, 02. pressure detection module, 03. mode selection switch, 1. upper shell, 2. glass sintering block, 3. signal pin, 4. acceleration core shell monomer, 5. acceleration sensitive ceramic sheet, 6. acceleration core mass, 7. pressure core shell monomer, 8. insulating block, 9. electrode sheet, 10. pressure sensitive ceramic sheet, 11. lower shell, 12. double-core cable, 13. cable metal inner sleeve, 14. cable connector pin, 15. cable connector glass sintering seat, 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. dial block, 25. conductor column, 26. first contact, 27. second contact, 28. third contact, 29. fourth contact, 30. fifth contact, 31. sixth contact, 32. shorting piece, 33. pressure sensing hole. DETAILED DESCRIPTION

[0025] In order to make the purpose, features and advantages of the present application more obvious and easy to understand, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the specific embodiments. Obviously, the embodiments described below are only some of the embodiments of the present application, not all. Based on the embodiments in the present patent, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present patent.

[0026] Embodiment one As shown in Figure 1 , 2 , an acceleration and pressure composite sensor based on a shear type structure, which is a hexagonal prism structure as a whole, comprising an upper shell 1 and a lower shell 11, the top surface of the upper shell 1 is provided with a double-core connector, and the bottom surface of the lower shell 11 is provided with a mounting stud for mounting itself to the detection object, the upper shell 1 and the lower shell 11 are provided with an acceleration detection module 01 and a pressure detection module 02: The center of the upper shell 1 is provided with a through hole, two signal pins 3 are arranged in the through hole, and the through hole is filled with glass powder, and the signal pins are fixed by high-temperature sintering to form a glass sintering block 2 and form a double-core connector structure.

[0027] As shown in Figure 2As shown, the acceleration detection module 01 comprises an acceleration core and an acceleration core shell, the acceleration core comprises an acceleration core mass block 6, the acceleration core mass block 6 is a regular hexagonal 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 compressed between the outer periphery of the acceleration core mass block 6 and the inner periphery of the acceleration core shell, the acceleration core mass block 6 is made of conductive material and is connected with a signal pin 3, after the sensor is installed, when the detection object is displaced, the acceleration core mass block 6 remains stationary under the action of inertia, and then shear force is generated on the acceleration sensitive ceramic sheet 5, and charge output is generated: the vibration acceleration generates inertial shear force through the mass block, acts on the piezoelectric ceramic, and 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 shear deformation. The charge sensitivity (Sa) calculation formula is: Sa=d15xm×n, wherein d15 is the piezoelectric coefficient of the ceramic, m is the mass of the mass block, and n is the number of ceramic sheets.

[0028] The pressure detection module 02 comprises a pressure core and a pressure core shell, the pressure core comprises a force transmission column 17, the force transmission column 17 is arranged at the center position of the upper surface of the lower shell 11, specifically, the top surface of the lower shell 11 is provided with a groove 18 at the center, the groove 18 is communicated to the pressure sensing hole 33 at the center of the bottom surface of the lower shell 11, the cross section of the groove 18 is circular, the membrane 19 is arranged in the groove 18, the outer edge of the membrane 19 is fixedly connected with the inner side wall of the groove 18, the center position of the membrane 19 is convex, the force transmission column 17 is installed at the center vertex of the membrane 19, the force transmission column 17 is a regular hexagonal structure, each side of the force transmission column 17 is sequentially provided with a pressure sensitive ceramic sheet 10, an electrode sheet 9 and an insulating block 8 from inside to outside, the edges of adjacent electrode sheets 9 are in contact with each other, the pressure sensitive ceramic sheet 10, the electrode sheet 9 and the insulating block 8 are compressed between the outer periphery of the force transmission column 17 and the inner periphery of the pressure core shell, a through hole is formed in the acceleration core mass block 6 in the up-down direction, at least one of the plurality of electrode sheets 9 is connected to another signal pin 3 through a wire, and the wire passes through the through hole in the acceleration core mass block 6. In this way, when subjected to pressure, the membrane structure can produce large deformation, push the force transmission column 17 located at the center to produce displacement, so that shear force is generated on the ceramic surface, and charge output is generated: the measured pressure is converted into shear force through the membrane, acts on the piezoelectric ceramic, and then outputs charge through the d15 effect. The charge sensitivity (Sa) calculation formula is Sa=d15×k×A×n, wherein d15 is the piezoelectric coefficient of the ceramic, k is the pressure-shear force conversion coefficient, A is the stress area of the ceramic, and n is the number of ceramic sheets.

[0029] Further, in the conventional pressure or shear type sensor, the pre-tightening force of the core comes from the sensor assembly outside the shell pressurized, the shell is deformed to achieve, after the external pressure is removed, the shell will rebound to a certain extent, resulting in the actual pre-tightening force is reduced and difficult to accurately control, for this, in the scheme, the acceleration core shell and the pressure core shell adopt a split structure: As shown, adapted to the internal six-prism core structure, the acceleration core shell includes six acceleration core shell units 4, the acceleration core shell units 4 are respectively located on the outer side of the six acceleration sensitive ceramic pieces 5, the acceleration core shell unit 4 is a four-prism structure with an isosceles trapezoidal cross section, and the two base angles of the trapezoid are 60°, the sides of the corresponding two waists of the plurality of acceleration core shell units 4 are sequentially attached, the acceleration sensitive ceramic piece 5 is compressed between the acceleration core mass 6 and the side of the corresponding trapezoidal short base of the corresponding acceleration core shell unit 4, in assembly, the six acceleration core shell units 4 are matched with the central acceleration core, the acceleration core shell unit 4 is pressurized by the external vise and the like, after pressurization, the six acceleration core shell units 4 are welded and fixed at the joint, the way of first compression and then welding avoids the rebound problem of the traditional reduced diameter pressurization, ensuring the stability of the pre-tightening force; similarly, the pressure core shell includes six pressure core shell units 7, the pressure core shell units 7 are located on the outer side of the insulating block 8, the pressure core shell unit 7 is a four-prism structure with an isosceles trapezoidal cross section and a base angle of 60°, the sides of the corresponding two waists of the plurality of pressure core shell units 7 are sequentially attached and fixedly connected, the pressure sensitive ceramic piece 10, the electrode piece 9 and the insulating block 8 are compressed between the outer peripheral surface of the force transmission column 17 and the side of the corresponding trapezoidal short base of the corresponding pressure core shell unit 7. Further, the height of the pressure core is less than the height of the pressure core shell, the pressure core is located at the lower part of the inside of the pressure core shell, the acceleration core shell is located above the pressure core shell, and the pressure core and the acceleration core are spaced apart by a certain distance.

[0030] The composite sensor can realize signal transmission through a double-core cable 12 as shown. Figure 3 The double-core cable 12 is provided with a metal inner sleeve 13 at the lower end, the metal inner sleeve 13 is provided with a cable connector glass sintering seat 15 inside, two cable connector pins 14 are sintered and fixed in the cable connector glass sintering seat 15, a knurled nut 16 is provided outside the cable connector glass sintering seat 15, the knurled nut 16 can rotate relative to the cable connector glass sintering seat 15, during installation, the cable connector glass sintering seat 15 is inserted into the double-core connector of the composite sensor, the two cable connector pins 14 are connected with the two signal pins 3 respectively, and then the knurled nut 16 is screwed onto the top stud of the upper shell 1.

[0031] Further, a mode selection switch 03 can be installed on the double-core connector or the double-core cable 12, as shown in the figure. Figure 4 The mode selection switch 03 includes an acceleration output line 22 and a pressure output line 23 arranged in parallel, an acceleration input electrode 20 arranged above the acceleration output line 22, a pressure input electrode 21 arranged above the pressure output line 23, and two dial blocks 24 arranged on the acceleration output line 22 and the pressure output line 23 respectively, and the two dial blocks 24 are fixedly connected in insulation. A conductor column 25 is arranged on the upper surface of the dial block 24. The first contact 26 and the third contact 28 are arranged on the side of the pressure input electrode 21. The second contact 27 and the fourth contact 29 are arranged on the side of the acceleration input electrode 20. The first contact 26 and the second contact 27 are arranged in staggered positions in the extension direction of the pressure output line 23, and the third contact 28 and the fourth contact 29 are arranged in the same position and face each other. When the dial block 24 is dialled to different set positions, the conductor column 25 on the dial block 24 is in contact with the corresponding position of the contact. The fifth contact 30 is arranged on the side of the end of the acceleration input electrode 20, and the sixth contact 31 is arranged on the side of the end of the pressure input electrode 21. The mode selection switch 03 also has a shorting piece 32. When the dial block 24 is dialled to the end of the acceleration input electrode 20 and the pressure input electrode 21, the two conductor columns 25 are in contact with the fifth contact 30 and the sixth contact 31 respectively, and at the same time in contact with the shorting piece 32.

[0032] Based on the mode selection switch, the composite sensor has four output modes: Single pressure signal output: dial the dial block 24 to the position of the first contact 26, one of the two conductor columns 25 is in contact with the first contact, and the other conductor column is not in contact with any contact. At this time, the pressure input electrode 21 is in communication with the pressure output line 23, and the composite sensor outputs the pressure signal; Single acceleration output: dial the dial block 24 to the position of the second contact 27, one of the two conductor columns 25 is in contact with the second contact 27, and the acceleration input electrode 20 is in communication with the acceleration output line. The composite sensor outputs the acceleration signal; Acceleration and pressure output at the same time: dial the dial block 24 to the position of the third contact 28 and the fourth contact 29. At this time, one of the two conductor columns 25 is in contact with the third contact 28, and the pressure input electrode 21 is in communication with the pressure output line 23. The other conductor column 25 is in contact with the fourth contact 29, and the acceleration input electrode 20 is in communication with the acceleration output line 22. The composite sensor outputs the acceleration and pressure signals; Pressure sensor signal output with compensation function: move the dial 24 to the position of the fifth contact 30 and the sixth contact 31, at this time the two conductor columns are in contact with the fifth contact 30 and the sixth contact 31 respectively, and the two ends of the shorting piece 32 are in contact with the two conductor columns respectively, at this time the acceleration input electrode 20 and the pressure input electrode 21 are short-circuited, and the acceleration noise in the acceleration signal and the pressure signal cancel each other out: the total signal of the pressure output is superimposed by 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 related only to pressure, the core formula is Q p = Q T -Q a , wherein Q p is the true signal charge of the pressure sensor, Q T is the total output charge, and Q a is the output charge of the acceleration sensor, in this way, the composite sensor can output a pressure signal with acceleration compensation, solving the problem that when measuring in a vibrating / impacting environment, the additional deformation of the piezoelectric material caused by acceleration (inertial force interference) is misjudged as a pressure signal, realizing accurate pressure measurement in a vibrating / impacting environment, especially suitable for scenarios where pressure is the core measurement target but environmental acceleration interference is unavoidable, for example, the engine compartment and chassis of a car, the high-frequency vibration (100-1000Hz) of the engine when running will cause ordinary sensors to output "pressure fluctuation artifacts", ordinary piezoelectric pressure sensors are easily disturbed by acceleration, leading to pressure measurement deviation, while the model with acceleration compensation can accurately capture the true pressure, and after acceleration compensation, the vibration interference can be corrected in real time, ensuring the accuracy of fuel rail pressure measurement.

[0033] Embodiment two The embodiment further provides an assembly method of an acceleration and pressure composite sensor based on a shear type structure, comprising the following steps: S1. Paste acceleration sensitive ceramic sheets 5 on the periphery of the acceleration core mass block 6, paste acceleration core shell monomers 4 on the outer side of the acceleration sensitive ceramic sheets 5, apply a pre-tightening force perpendicular to the side surface of the acceleration core mass block 6 to the acceleration core shell monomer 4, weld at the gap where the acceleration core shell monomers 4 contact, and weld a first lead wire on the acceleration core mass block 6 to complete the assembly of the acceleration detection module 01; S2. Paste a plurality of groups of pressure sensitive ceramic sheets 10, electrode sheets 9, insulating blocks 8 and pressure core shell monomers 7 to the plurality of side surfaces of the force transmission columns 17 of the lower shell 11 in sequence, and apply a pre-tightening force perpendicular to the side surface of the force transmission column 17 to the pressure core shell monomer 7, weld at the gap where the pressure core shell monomers 7 contact, and weld a second lead wire on any one of the electrode sheets 9 to complete the assembly of the pressure detection module 02 and the lower shell 11. S3. The second lead wire is passed through the through hole in the center of the acceleration core mass 6, and then the acceleration detection module 01 is placed above the pressure detection module 02, and welding is performed at the gap where the acceleration detection module 01 and the pressure detection module 02 are in contact; S4. The first lead wire and the second lead wire are respectively welded to the lower ends of the two signal pins 3 in the upper shell 1, and then the upper shell 1 is placed above the acceleration detection module 01, and welding is performed at the gap where the acceleration detection module 01 and the upper shell 1 are in contact. S5. The mode selection switch 03 is installed on the double-core connector of the upper shell 1, and the two signal pins 3 are respectively connected with the acceleration input electrode 20 and the pressure input electrode 21 of the mode selection switch 03; or the double-core cable 12 is installed on the double-core connector.

[0034] Through the above technical scheme, the beneficial effects of the present application are as follows: 1. In terms of overall structure design, the present composite sensor adopts a shear type piezoelectric structure, realizing miniaturized design. In traditional monitoring scenarios, acceleration and pressure need to be collected by “acceleration sensors” and “pressure sensors” respectively, while the present composite sensor can output acceleration and pressure signals synchronously in the same space-time dimension through integrated double detection modules, not only reducing the number of devices and installation steps, but also avoiding the “time difference” between multiple devices. In addition, the overall design of the sensor can be less than 15mm in height and less than 7.5mm in installation diameter. The miniaturized structure design enables the sensor to achieve multi-dimensional breakthroughs in “space adaptability, performance optimization, and scenario expansion”, solving the application limitations of traditional large-size devices and significantly improving the inherent frequency through miniaturized structure design, covering higher frequency dynamic signals.

[0035] 2. In terms of shear structure design, piezoelectric pressure sensors generally use compression sensitive elements. To improve the charge sensitivity of the sensor itself, only the force area of the piezoelectric ceramic and the number of stacked sensitive ceramic sheets can be increased, which often contradicts the original intention of miniaturized design. The shear type piezoelectric pressure sensor structure design can solve this drawback. The sensitivity of the shear sensitive element is determined by the “shear piezoelectric coefficient (d15, higher than the compression type structure) of the piezoelectric material” and the “structure size”. Therefore, the designed shear type pressure sensor adopts a hexagonal mounting surface to increase the force structure size, so that the micro sensor can output a sensitivity of >20000pC / MPa. The higher the sensitivity, the greater the piezoelectric charge generated under the same pressure change, and the easier it is to be recognized by the subsequent signal conditioning circuit. 20000pC / MPa belongs to the high sensitivity level, and its core value can solve the problem of difficult measurement of “low pressure, small pressure fluctuation such as 0.05MPa”.

[0036] 3. Shell design and pre-tightening mechanism: The traditional piezoelectric sensor shell is usually designed as a whole shell, which is used for sealing and protecting the internal core. The pre-tightening mechanism adopts a pressurized pre-tightening mechanism, which is prone to pressure relief and rebound problems. Therefore, the composite sensor is designed as a six-part trapezoidal structure, which can pre-tighten the internal core two by two after mutual docking. The pre-tightening force can be maintained after welding, thereby improving the stiffness of the sensor elastic system.

[0037] 4. Pressure detection module diaphragm structure design: The pressure can be directly and losslessly transmitted from the lower shell of the structure to the sensitive area of the ceramic. In addition, the concave structure of the diaphragm can change the stress concentration area and deformation trajectory after the diaphragm is stressed by using the "convex structure", thereby increasing the stress accuracy of the sensor.

[0038] 5. Multi-mode output function design: The traditional piezoelectric sensor usually has single function and single use scene. The composite sensor outputs acceleration and pressure signals through a double-core cable, and the adapter module is provided with a dial switch, which can realize multi-mode output function, so that it has only acceleration signal monitoring, only pressure signal monitoring, simultaneous monitoring of acceleration and pressure signals, and monitoring of pressure signals with acceleration compensation function.

[0039] The above description of disclosed embodiments enables those skilled in the art to carry out or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to 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, It includes an upper housing (1) and a lower housing (11), and 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) 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). The force transmission column (17) 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), 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.

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 lower housing (11) has a groove (18) at the center of its top surface. The groove (18) has a circular cross-section. 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 of the diaphragm (19) is convex. The force transmission column (17) is installed at the center apex of the diaphragm (19).

5. 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.

6. The shear-based acceleration and pressure composite sensor according to claim 1, characterized in that, The upper housing (1) is provided with a dual-core connector, which 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 electrode plate (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).

7. The shear-based acceleration and pressure composite sensor according to claim 6, 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.

8. The shear-based acceleration and pressure composite sensor according to claim 7, 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).

9. 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.

10. The assembly method of the shear-based acceleration and pressure composite sensor according to claim 9, 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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