Miniature triaxial plane shear type acceleration measurement sensitive structure

Abstract

The invention provides a miniature three-axial plane shearing type acceleration measurement sensitive structure. The miniature three-axial plane shearing type acceleration measurement sensitive structure comprises a piezoelectric sensitive element, a mounting base, an inertial mass block, a locking screw and a lead sheet, the three-direction vibration parameter measurement of a measured object can be realized through the threaded connection of a mounting base threaded hole to which the sensitive structure belongs and the measured object. Through cooperation of the mounting base, the piezoelectric sensitive element, the inertial mass block, the locking screw and the lead piece, the sensitive assembly is of a three-direction plane shearing structure, and three-direction vibration parameter measurement can be achieved; the sensitive assembly is high in measurement precision, high in reliability and high in universality, and can adapt to more application scenes. Through the compact layout of three-face threaded hole assembly and the design of the isolated frustum base and the tandem piezoelectric element, high precision and miniaturization of multi-axial synchronous measurement are achieved, meanwhile, strain interference of the base is effectively isolated, and the requirement for in-situ contact type precision measurement is met.

Description

Technical Field

[0001] This invention relates to the field of measurement and testing technology, and specifically to a miniature triaxial planar shear acceleration measurement sensitive structure. Background Technology

[0002] Vibration measurement plays a vital role in industrial production and scientific research. Uncontrolled vibration not only generates noise pollution but also induces mechanical stress concentration, which can lead to structural failure in severe cases. Currently, vibration measurement is mainly used in vibration testing, equipment condition monitoring, fault diagnosis, structural dynamics analysis, and ergonomics. Particularly in the fields of mechanical equipment condition monitoring and structural analysis, stringent requirements are placed on the size, reliability, and anti-interference performance of sensors.

[0003] From the perspective of sensing structure, existing accelerometers are mainly divided into three types: compression, shear, and bending. Among them, the shear structure has significant advantages over the traditional compression structure: lower lateral sensitivity, effectively reducing measurement crosstalk; higher structural reliability, less prone to electrical open circuit problems; and superior frequency response characteristics. These characteristics make the shear structure a prominent advantage in the field of precision acceleration measurement. Integrating triaxial sensing elements at the same measuring point not only reduces system costs but also enables simultaneous acquisition of multi-directional vibration data, significantly improving measurement efficiency.

[0004] While piezoelectric accelerometers are widely used in various vibration measurement fields, domestically produced triaxial shear sensors still have significant shortcomings: measurement accuracy needs improvement, overall weight is relatively large, and the operating frequency range is narrow. These problems severely restrict the sensor's application in long-term precision measurements. Especially in scenarios requiring in-situ contact measurements, existing sensors struggle to simultaneously meet the requirements of miniaturization, high precision, and wide bandwidth. Furthermore, traditional structures also have room for improvement in areas such as base strain isolation and signal extraction reliability.

[0005] Therefore, a miniaturized, high-precision, and wide-bandwidth triaxial shear sensor is needed. Summary of the Invention

[0006] This invention addresses the miniaturization and accuracy issues of triaxial shear sensors by providing a miniature triaxial planar shear acceleration measurement sensing structure. The sensing structure is screwed onto the object being measured via threaded holes in the mounting base, enabling the measurement of three-directional vibration parameters. Through the cooperation of the mounting base, piezoelectric sensing element, inertial mass block, locking screw, and lead wire, the sensing component is a three-directional planar shear structure, capable of measuring three-directional vibration parameters. This sensing component offers high measurement accuracy, strong reliability, and wide versatility, adaptable to numerous application scenarios. This application achieves high precision and miniaturization for multi-axial synchronous measurement through a compact layout with three-sided threaded holes, an isolated frustum-shaped base, and a series-connected piezoelectric element design, while effectively isolating base strain interference and meeting the requirements of in-situ contact precision measurement.

[0007] This invention provides a miniature triaxial planar shear acceleration measurement sensitive structure, including a mounting base and three sets of mass-spring assemblies connected to the mounting base in three directions by locking screws. The mass-spring assembly consists of a double-plate clamping structure and an inertial mass block connected sequentially from the inside to the outside. The double-plate clamping structure consists of two piezoelectric sensitive elements and a lead sheet clamped between the two piezoelectric sensitive elements. The mounting base includes a mounting base body, a bottom threaded hole connected to the bottom of the mounting base body and extending upward, a hexahedron connected to the top of the mounting base body, and a first threaded hole, a second threaded hole, and a third threaded hole connected in sequence in three directions of the hexahedron. The first threaded hole, the second threaded hole, and the third threaded hole correspond to three measuring axes, and are respectively threaded to the mass-spring assembly through locking screws. The bottom surface of the mounting base is the mounting surface of the acceleration measurement sensitive structure, which is rigidly connected to the object being measured through a threaded hole at the bottom. The acceleration measurement sensitive structure has its center of gravity vector direction perpendicular to the mounting surface in the same vertical plane as the axis of the bottom threaded hole. The three sets of mass-spring assemblies can independently detect acceleration signals in three directions.

[0008] In a preferred embodiment of the miniature triaxial planar shear acceleration measurement sensitive structure described in this invention, the hexahedron is a rectangular metal body with different lengths and widths. The first threaded hole and the third threaded hole are connected through each other and are both located in the long direction of the hexahedron. The second threaded hole extends and penetrates the hexahedron. The bottom threaded hole does not contact the first threaded hole, the second threaded hole, and the third threaded hole. The mounting base also includes an isolated frustum structure connecting the upper surface of the mounting base body and the bottom of the hexahedron. The length and width of the upper part of the isolated frustum structure are greater than the length and width of the bottom of the hexahedron. The isolated frustum structure is a gradually sloping surface that is wide at the bottom and narrow at the top.

[0009] The miniature triaxial planar shear acceleration measurement sensing structure of the present invention, as a preferred embodiment, has an isolated frustum structure that is a gradually changing inclined surface with a height-to-bottom diameter ratio of 1:2 to 1:3; A transition plane connects the top of the isolated frustum structure to the bottom of the hexahedron. The bottom of the inertial mass block is provided with a clearance groove to increase the gap between the bottom of the inertial mass block and the isolated frustum structure.

[0010] The present invention discloses a miniature triaxial planar shear acceleration measurement sensitive structure, wherein, in a preferred embodiment, the inertial mass block includes a mass block body, a notched structure located at the rear of the inertial mass block, a wire outlet groove connected to the upper part of the mass block body, and a mass block screw mounting hole that passes through and connects to the mass block body. The corner-cut structure is a structure that forms an asymmetrical geometric shape by cutting the rear part of the inertial mass block by beveling or step cutting. The volume is reduced by reducing the material of the inertial mass block through the corner-cut structure. The cable outlet is a groove structure connected to the top of the inertial mass block; The lead sheet includes a lead sheet body with a sheet-like structure, a lead sheet screw mounting hole connected to the center of the lead sheet body, and a sheet-like lead connected to the top center of the lead sheet body and extending upward. The width of the sheet-like lead is smaller than the width of the lead sheet body. The lead wire is made of metal; After the acceleration measurement sensitive structure is assembled, the height of the sheet lead is higher than that of the piezoelectric sensitive element and the lead slot. The lead slot allows the lead sheet to be led from the side and connected to the signal wire at the external connection point.

[0011] In a preferred embodiment of the miniature triaxial planar shear acceleration measurement sensitive structure described in this invention, the signal wire and the motion plane of the inertial mass block are spatially perpendicular, and the sidewall of the wire outlet groove physically limits the lead sheet. The inertial mass block is obtained by machining a tungsten alloy cube with a missing corner; The four sides of the lead sheet body are of equal length and the included angle is a right angle. The length and width of the piezoelectric sensitive element are greater than or equal to the length and width of the lead sheet body. The lead screw mounting hole and the locking screw are installed with a gap, and the diameter of the lead screw mounting hole is larger than the outer diameter of the locking screw; The lead wire is made of gold-plated copper.

[0012] In the present invention, a miniature triaxial planar shear acceleration measurement sensitive structure is preferably provided, wherein the piezoelectric sensitive element is a rectangular thin-film piezoelectric ceramic. In each set of dual-plate clamping structures, two piezoelectric sensitive elements are connected in series by conductive adhesive or welding.

[0013] In the present invention, a miniature triaxial planar shear acceleration measurement sensitive structure is preferably made of lead zirconate titanate-based ceramic material.

[0014] The present invention discloses a miniature triaxial planar shear acceleration measurement sensitive structure, wherein, in a preferred embodiment, the locking screw comprises a screw head, a screw rod, a transition zone, a threaded zone, and an embedded mounting hole connected in sequence inside the screw head; After the acceleration measurement sensitive structure is assembled, the outer surface of the screw head is flush with the outer surface of the inertial mass block, the threaded area is connected to the internal thread of a threaded hole, a second threaded hole, or a third threaded hole, and the transition zone is located between the double-plate clamping structures. The transition zone is oxidized to form an insulating layer, preventing the locking screw from forming a parasitic conductive circuit.

[0015] In a preferred embodiment of the miniature triaxial planar shear acceleration measurement sensitive structure described in this invention, the transition region is subjected to hard black anodizing to generate an aluminum oxide insulating layer with a thickness of 5~25μm and a Vickers hardness of 400HV or higher. The locking screw is made of titanium alloy.

[0016] The present invention discloses a miniature triaxial planar shear acceleration measurement sensitive structure. As a preferred embodiment, the assembly method of the acceleration measurement sensitive structure is as follows: During assembly of each axis, firstly, the piezoelectric sensitive element of a set of mass-spring assemblies is attached to one wall of a hexahedron. Then, a lead wire is placed and its through hole is aligned with the first threaded hole, the second threaded hole, or the third threaded hole. Next, a second piezoelectric sensitive element is stacked to form a double-piece clamping structure. Finally, an inertial mass block is installed, and axial preload is applied by passing a locking screw through the inertial mass block, the second piezoelectric sensitive element, the lead wire, and the first piezoelectric sensitive element in sequence into the hexahedron. The three sets of piezoelectric sensitive elements are assembled in sequence, and the three sets of piezoelectric sensitive elements form independent mass-spring assemblies in the orthogonal direction. The measurement method of the acceleration measurement sensitive structure is as follows: when the object being measured vibrates, the shear force generated by the inertial mass block acts on the piezoelectric sensitive element, generating a charge signal proportional to the acceleration. The lead wire is embedded between the two piezoelectric sensitive elements, directly collecting the charge and leading out the wire through the protruding end.

[0017] The structure of this invention includes a piezoelectric sensing element, a mounting base, an inertial mass block, a locking screw, and a lead wire. The sensing element is screwed to the object under test through the threaded hole of the mounting base, enabling the measurement of three-directional vibration parameters of the object. Through the cooperation of the mounting base, piezoelectric sensing element, inertial mass block, locking screw, and lead wire, the sensing component of this invention has a three-directional planar shear structure, enabling the measurement of three-directional vibration parameters. This sensing component offers high measurement accuracy, strong reliability, and wide versatility, making it suitable for numerous application scenarios.

[0018] This application achieves high precision and miniaturization of multi-axial synchronous measurement through a compact layout of three-sided threaded hole assembly, an isolated frustum base, and a series piezoelectric element design, while effectively isolating base strain interference and meeting the requirements of in-situ contact precision measurement.

[0019] The present invention has the following advantages: (1) Through reasonable structural design, the present invention enables the mounting axis center of gravity of the micro triaxial planar shear acceleration measurement sensitive structure to be located coaxial with the mounting threaded hole of the base, which can realize the in-situ measurement of vibration parameters of the measuring point. Compared with the existing triaxial vibration sensor structure, the measurement accuracy is improved.

[0020] (2) By selecting a new type of piezoelectric sensitive element 2 with a wide temperature range and cooperating with other components, the present invention enables the product to be used normally in the temperature range of -100℃ to +280℃.

[0021] (3) The overall structure of the present invention is a planar shear structure and is equipped with an isolation base, which can effectively shield the spurious response and improve the signal-to-noise ratio of the vibration signal measured by the present structure.

[0022] (4) The present invention can measure the three-dimensional vibration parameters of the measuring point, and has a small design size, light weight, and strong environmental adaptability to the measuring point environment. Attached Figure Description

[0023] Figure 1 A three-dimensional schematic diagram of a miniature triaxial planar shear acceleration measurement sensitive structure; Figure 2 This is a three-dimensional schematic diagram of a miniature triaxial planar shear acceleration measurement sensitive structure from another direction. Figure 3 A three-dimensional diagram of the mounting base for a miniature triaxial planar shear acceleration measurement sensitive structure; Figure 4 A cross-sectional view of a miniature triaxial planar shear acceleration measurement sensitive structure; Figure 5 A schematic diagram of a piezoelectric sensing element for a miniature triaxial planar shear acceleration measurement sensing structure; Figure 6A front view of an inertial mass block of a miniature triaxial planar shear acceleration measurement sensitive structure; Figure 7 Rear view of an inertial mass block of a miniature triaxial planar shear acceleration measurement sensitive structure; Figure 8 A three-dimensional diagram of a locking screw for a miniature triaxial planar shear acceleration measurement sensitive structure; Figure 9 A three-dimensional diagram of a lead sheet for a miniature triaxial planar shear acceleration measurement sensitive structure.

[0024] Figure label: 1. Mounting base; 11. Mounting base body; 12. Bottom threaded hole; 13. Hexahedron; 14. First threaded hole; 15. Second threaded hole; 16. Third threaded hole; 17. Isolated frustum structure; 2. Piezoelectric sensitive element; 3. Inertial mass block; 31. Mass block body; 32. Notched corner structure; 33. Outlet groove; 34. Mass block screw mounting hole; 4. Locking screw; 41. Screw head; 42. Screw rod body; 43. Transition area; 44. Threaded area; 45. Embedded mounting hole; 5. Lead wire piece; 51. Lead wire piece body; 52. Lead wire piece screw mounting hole; 53. Sheet-shaped lead wire. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Example 1

[0026] like Figures 1-9 As shown, a miniature triaxial planar shear acceleration measurement sensitive structure includes a mounting base 1, a piezoelectric sensing element 2, an inertial mass block 3, a locking screw 4, and a lead wire 5. The mounting base 1 is screwed to the object being measured through a threaded mounting hole at its bottom. The mounting base 1 has threaded holes on three sides, and the piezoelectric sensing element 2, lead wire 5, and inertial mass block 3 are assembled sequentially from the inside out. The locking screw 4 is used to lock the acceleration measurement sensitive structure. The signal core wire is led out through the lead wire 5 to achieve signal transmission.

[0027] In existing technologies, piezoelectric accelerometers are widely used in vibration measurement. However, traditional triaxial shear sensors suffer from problems such as large size, insufficient measurement accuracy, and limited operating frequency range. In precision machinery condition monitoring scenarios, the internal space of the equipment is limited, and long-term continuous acquisition of multi-directional vibration data is required. Existing sensors are difficult to install due to structural redundancy, and their high lateral sensitivity affects the separation of multi-axial signals, making it difficult to meet the requirements of high-precision measurement.

[0028] To address the aforementioned issues, researchers discovered that traditional compression-type sensitive structures suffer from drawbacks such as significant base strain interference and substantial lateral crosstalk. While shear-type layouts can reduce lateral sensitivity, their structure becomes complex when integrated across multiple axes. Analysis revealed that a three-way symmetrical threaded hole design simplifies the assembly process, and a planar stacked arrangement reduces the overall volume. Further considering the impact of the signal transmission path on the signal-to-noise ratio, an embedded layout of the lead sheet 5 shortens the wire length. Based on this, a stacked assembly scheme was developed, with a three-sided threaded hole mounting base 1 as the core, combined with dual piezoelectric sensitive elements 2 clamping the lead sheet 5.

[0029] Therefore, this application is filed.

[0030] In this embodiment, the mounting base 1 refers to the base structure that supports each component and is rigidly connected to the object being measured. Specifically, it can be implemented by a metal block with threaded holes on three sides. The threaded hole 12 at the bottom is used for fixed installation, and the threaded holes on the three sides form an orthogonal coordinate system positioning reference.

[0031] The piezoelectric sensitive element 2 refers to the transducer that converts mechanical stress into electrical signals. Specifically, it can be implemented using rectangular thin-film piezoelectric ceramic material, with its polarization direction parallel to the shear plane to enhance sensitivity.

[0032] The inertial mass block 3 refers to the counterweight structure that provides inertial force. Specifically, it can be made by machining a tungsten alloy cube with a notched groove. Its mass distribution is calculated to match the preset resonant frequency.

[0033] Locking screw 4 refers to a fastener that applies preload to maintain the mechanical coupling between components. Specifically, it can be implemented using a titanium alloy screw with mid-section insulation to prevent current leakage from interfering with the signal.

[0034] Lead sheet 5 refers to the conductive component that transmits electrical signals. Specifically, it can be made by stamping a square thin sheet with through holes from a gold-plated copper sheet. The through holes are used to pass through the locking screw 4, and the protruding end is welded with signal wires.

[0035] Specifically, the mounting base 1 is rigidly connected to the object being measured via the bottom threaded hole 12, eliminating relative displacement errors. The three threaded holes (first threaded hole 14, second threaded hole 15, and third threaded hole 16) correspond to the three measurement axes. During assembly along each axis, the piezoelectric sensitive element 2 is first attached to the inner wall of the base. Then, the lead wire piece 5 is placed so that its through-hole aligns with the threaded hole. Next, a second piezoelectric sensitive element 2 is stacked to form a double-piece clamping structure. Finally, the inertial mass block 3 is installed, and axial preload is applied via the locking screw 4. This stacked assembly allows the three sets of sensitive elements to form an independent mass-spring system in orthogonal directions. When the object being measured vibrates, the shear force generated by the inertial mass block 3 acts on the piezoelectric sensitive element 2, generating a charge signal proportional to the acceleration. The lead wire piece 5 is embedded between the two piezoelectric sensitive elements 2, directly collecting the charge and leading out a wire through its protruding end, avoiding electromagnetic interference introduced by long-distance wiring.

[0036] Compared to existing technologies, traditional triaxial sensors employ a split housing structure, with three sensing units installed independently, leading to increased size. This solution, however, integrates the sensors using three threaded holes, allowing all three measurement axes to share the same mounting base 1 and inertial mass block 3, significantly reducing the overall size. Existing technologies often suffer from insufficient signal strength due to single-layer piezoelectric element arrangement; this solution uses a dual-piezoelectric element series structure, increasing charge output within the same space. Furthermore, unlike traditional side-lead methods which are susceptible to mechanical stress, this solution uses lead plates 5 in planar contact with the piezoelectric element, maintaining a stable electrical connection through screw preload.

[0037] Through the above technical solutions, this application achieves miniaturization of the sensor size, improves the integration of the triaxial sensing element to reduce the overall weight, effectively suppresses lateral sensitivity with the planar shear layout, expands the operating frequency range with the dual piezoelectric sheet series structure, and ensures signal transmission stability with the embedded design of the lead sheet 5, meeting the long-term accurate measurement requirements of multi-directional vibration parameters in confined spaces.

[0038] This application further proposes a micro triaxial planar shear acceleration measurement sensitive structure with its center of gravity vector direction perpendicular to the mounting surface located directly above the mounting threaded hole, enabling in-situ contact measurement of the measured structure.

[0039] Among them, the direction of the center of gravity vector refers to the direction of the resultant force generated by the overall mass distribution of the sensitive structure. Specifically, it can be achieved by adjusting the geometric symmetry between the inertial mass block 3 and the mounting base 1. When this direction coincides with the axis of the mounting threaded hole, it can eliminate the torque imbalance caused by the offset of the center of gravity.

[0040] The phrase "directly above the mounting threaded hole" refers to the fact that the axis of the bottom threaded hole 12 and the direction of the center of gravity vector are in the same vertical plane. This can be achieved by optimizing the relative positional relationship between the mounting base 1 and the inertial mass block 3 through finite element simulation. This design ensures that the mechanical transmission path is consistent with the direction of the inertial force when the sensor is installed.

[0041] Specifically, after the mounting base 1 is fixed to the external object being measured, the inertial force generated by the inertial mass block 3 is transmitted to the mounting base 1 through the piezoelectric sensing element 2. When the direction of the center of gravity vector coincides with the axis of the threaded hole, the line of action of the inertial force passes through the center of the support surface of the mounting point, avoiding the generation of additional torque. In shear mode, the piezoelectric sensing element 2 only senses the acceleration component perpendicular to the mounting surface, and the center of gravity alignment design ensures that the sensing elements in all three axes are in a state of force without additional torque interference, thereby realizing independent detection of acceleration signals in three directions.

[0042] Compared to existing technologies, traditional shear-type sensors do not consider the spatial matching relationship between the center of gravity and the mounting point. After installation, the center of gravity shift can easily cause the sensitive element to experience lateral torque, leading to signal crosstalk. This solution optimizes the structural layout to achieve mechanical balance between the center of gravity vector and the mounting point, eliminating the negative impact of installation position deviation on the stress distribution of the sensitive element.

[0043] Through the above technical solution, this application solves the problem of measurement error accumulation caused by sensor installation position, forming a gapless rigid contact between the sensor housing and the measured object, avoiding signal attenuation caused by installation tilt. This design ensures that the acceleration load is transmitted along a preset mechanical path, so that the piezoelectric sensitive element 2 only responds to the vibration component in the target direction, thereby improving the orthogonality and repeatability of triaxial measurement data.

[0044] This application further proposes that the mounting base 1 adopts an isolated frustum structure 17, which can effectively isolate base strain and improve the signal-to-noise ratio.

[0045] Among them, the isolated frustum structure 17 refers to the geometric structure between the top of the mounting base body 11 and the bottom of the hexahedron 13 through a conical transition. Specifically, it can be achieved by adopting a gradually changing slope design with a ratio of 1:2 to 1:3 between the height of the frustum and the diameter of the bottom surface. By changing the continuity of the stress transmission path, the transmission of the base deformation-sensitive element is weakened.

[0046] Among them, the base strain refers to the local deformation of the mounting base 1 caused by external mechanical loads or temperature changes. Specifically, the strain transmission path can be blocked by the stress dispersion characteristics of the frustum structure, and an asymmetric load distribution can be formed by utilizing the inclination angle of the conical sidewall to reduce the coupling interference of base deformation on sensitive elements.

[0047] Specifically, the isolated frustum structure 17, through the geometric features of its conical sidewalls, disperses the strain energy transmitted from the base to the non-sensitive area along the inclined surface of the frustum. When an external mechanical load is applied to the mounting base 1, the inclined profile of the frustum structure causes the stress propagation path to deviate from the mounting plane of the sensitive element, forming a physical isolation layer. The difference in cross-sectional area between the top and bottom of the frustum further causes the strain to attenuate during transmission, so that the piezoelectric sensitive element 2 only responds to the acceleration signal perpendicular to the sensitive direction, while the parasitic charge signal generated by the strain of the base is suppressed.

[0048] Compared to existing technologies, traditional flat base structures cannot effectively block the direct transmission of base strain to the sensing element, resulting in deformation noise superimposed on the measurement signal. This solution utilizes the geometric isolation characteristics of a frustum structure to significantly reduce the interference of base strain on the sensing element while maintaining structural compactness, thus solving the problem of signal-to-noise ratio degradation caused by base deformation in existing sensors.

[0049] Through the above technical solution, this application can reduce the coupling interference of base strain on the output signal of piezoelectric sensitive element 2, suppress noise components in the measurement signal, ensure the accuracy of acceleration signal acquisition, and meet the requirements of high-precision vibration measurement.

[0050] This application further proposes two threaded holes on the side of the cuboid (hexahedron 13) above the mounting base 1. The position of the threaded holes should be designed so that the center of gravity of the micro triaxial planar shear acceleration measurement sensitive structure is located directly above the threaded holes after assembly.

[0051] Among them, the two threaded holes on the side of the cuboid above the mounting base 1 are connection structures set on the side of the mounting base 1 for fixing the piezoelectric sensitive element 2 and the inertial mass block 3. Specifically, they can be implemented in a symmetrical distribution manner, and the axis of the threaded holes forms a specific spatial relationship with the geometric center of the mounting base 1.

[0052] The center of gravity being located directly above the threaded hole means that the direction of the center of gravity vector formed by the overall mass distribution of the sensor coincides with the axis of the threaded hole. Specifically, this can be achieved by adjusting the vertical position of the threaded hole on the side of the mounting base 1, so that the center of gravity projection of the assembled inertial mass block 3 and piezoelectric sensitive element 2 falls on the axis of the threaded hole.

[0053] Specifically, the vertical positions of the two threaded holes on the side of the mounting base 1 are calculated to ensure that after the piezoelectric sensing element 2, lead plate 5, and inertial mass block 3 are sequentially assembled and secured with locking screws 4, the center of gravity vector direction of the entire sensing structure coincides with the axis of the threaded holes. During assembly, the position of the threaded holes constrains the relative positions of the components, ensuring that the line of action of the inertial force generated by the inertial mass block 3 passes through the axis of the threaded holes, thereby eliminating the additional torque caused by the offset of the center of gravity. This layout ensures that when the sensor is subjected to vibration and impact, the contact surface between the mounting base 1 and the locking screws 4 is subjected to uniform force, avoiding base deformation caused by local stress concentration, thus maintaining a stable contact state between the piezoelectric sensing element 2 and the inertial mass block 3.

[0054] Compared with existing technologies, traditional triaxial accelerometers do not fully consider the spatial matching relationship between the center of gravity and the mounting hole position, resulting in the overall center of gravity of the sensor deviating from the axis of the fixed point after assembly. This easily leads to torque imbalance in vibration environments, causing strain interference in the base measurement signal. This solution, through the coordinated design of the threaded hole position and the center of gravity vector, fundamentally suppresses the center of gravity shift caused by assembly errors or structural asymmetry.

[0055] Through the above technical solution, this application effectively reduces the local deformation of the sensor mounting surface caused by uneven force, enabling the piezoelectric sensitive element 2 to accurately sense vibration acceleration in three orthogonal directions. At the same time, it enhances the structural stability of the sensor in complex vibration environments and avoids the problem of measurement signal distortion caused by center of gravity shift.

[0056] This application further proposes that the inertial mass block 3 is provided with a wire outlet groove 33 above it, which can ensure that the lead wire piece 5 is reliably led out from the side.

[0057] Among them, the outgoing groove 33 refers to the groove structure set on the top of the inertial mass block 3, which can be realized by machining or molding process. The width of the groove matches the thickness of the lead piece 5 and is used to constrain the wiring path of the lead piece 5.

[0058] Among them, the side lead wire refers to the direction of the lead wire 5 being spatially perpendicular to the plane of motion of the inertial mass block 3. Specifically, this can be achieved by misaligning the opening direction of the lead wire groove 33 with the vibration direction of the mass block, so that the lead wire 5 remains isolated from the moving parts in the dynamic environment.

[0059] Specifically, the lead piece 5 is guided into the outlet groove 33 and extends along its sidewall to the external connection point. The sidewall of the outlet groove 33 physically limits the lead piece 5, preventing displacement during assembly due to screw tightening force or vibration impact. When the inertial mass block 3 vibrates, the fixed position of the lead piece 5 within the outlet groove 33 avoids direct contact with the piezoelectric sensitive element 2 or the locking screw 4, thereby eliminating signal interference caused by friction. The depth of the outlet groove 33 is designed to cover the full width of the lead piece 5, ensuring that it does not bend in the vertical direction.

[0060] Compared to existing technologies, traditional sensor lead sheets 5 typically pass directly through the surface or edge of the mass block, which is prone to twisting and breakage due to assembly gaps in miniaturized structures. This solution uses a directional lead groove structure to decouple the lead path from the direction of mass block movement, solving the lead compression problem caused by insufficient space and avoiding cable fatigue failure under vibration.

[0061] Through the above technical solution, this application achieves stable wiring of the lead piece 5 in a limited space, prevents electrical connection failure caused by structural interference or dynamic load, ensures the integrity of the signal transmission path, and improves the long-term reliability of the sensor under complex working conditions.

[0062] This application further proposes that the lower (rear) part (-XC direction) of the inertial mass block 3 is a corner-cut structure 32, and the inner side of the lower side should be designed to be higher than the inner side.

[0063] The notched corner structure 32 refers to the asymmetrical geometric shape formed by cutting the bottom of the inertial mass block body 31. This can be achieved by oblique cutting or stepped cutting. This structure removes unnecessary material while retaining the effective inertial mass area of ​​the mass block. The lower inner side dimension being higher than the inner side means that the bottom edge of the mass block forms a stepped raised structure. This can be achieved by machining steps with a height difference of 0.5 mm to 2 mm. This design maintains the contact area between the mass block and the piezoelectric sensitive element 2 within a limited space.

[0064] Specifically, when the mass block is subjected to triaxial acceleration, the notched structure 32 reduces its volume by decreasing the amount of material at the bottom, allowing the overall sensor size to be controlled within a 12 mm cube. The raised step on the lower inner side creates a gap with the mounting base 1 during assembly, preventing component interference due to machining errors. The effective contact surface of the mass block is maintained by preserving the complete top plane, ensuring that shear force is uniformly transmitted through the surface of the piezoelectric sensing element 2. Asymmetric cutting processing keeps the axial offset of the mass block's center of gravity within 0.1 mm, reducing the mechanical coupling effect between the measurement axes.

[0065] Compared to existing technologies, traditional triaxial sensor mass blocks employing symmetrical cubic structures result in excessively large axial dimensions. This solution, however, reduces volume by up to 30% with the same inertial mass through a corner-cut structure. In existing technologies, the flat bottom design of the mass block easily causes assembly interference with the mounting base 1. This solution's stepped structure allows for a safety clearance of 0.3 mm to 0.8 mm. The symmetrical distribution of the center of gravity in conventional mass blocks easily leads to axial crosstalk errors. This solution's asymmetrical structure reduces the sensitivity deviation in each axis to within 5%.

[0066] Through the above technical solution, this application effectively solves the problem of limited installation space caused by the large volume of the mass block of the sensor, avoids physical interference between components during assembly, and improves the independence and accuracy of triaxial acceleration measurement by optimizing the mechanical transmission path of the mass block.

[0067] This application further proposes that the two piezoelectric sensing elements 2 for measuring three directions adopt a series structure, the sensing acceleration directions of the three sets of piezoelectric sensing elements 2 are perpendicular to each other, and the piezoelectric sensing elements 2 are piezoelectric ceramics with a wide temperature range.

[0068] The series structure refers to connecting two piezoelectric sensing elements 2 end-to-end in the circuit to form a continuous signal transmission path. This can be achieved using conductive adhesive or welding. This structure enhances the output signal strength and reduces the impact of external interference on individual elements. The mutually perpendicular sensing acceleration directions mean that the mechanical sensing axes of the three piezoelectric sensing elements 2 form an orthogonal coordinate system in space. This can be achieved through precision machining of positioning grooves or mounting reference surfaces for directional assembly. This layout eliminates mechanical coupling effects between axes. The wide-temperature-resistant piezoelectric ceramic refers to a lead zirconate titanate-based ceramic material with temperature compensation characteristics. It can be prepared by doping with rare earth elements or adding stabilizers. This material has a stable piezoelectric constant within the temperature range of -55℃ to 260℃.

[0069] Specifically, when the acceleration components along the three axes act on the inertial mass block 3, each piezoelectric sensing element 2 only responds to the acceleration component aligned with its sensing direction. The series-connected piezoelectric sensing elements 2 enhance signal sensitivity through superimposed charge output, while the orthogonally arranged sensing directions eliminate cross-axis interference through spatial decoupling. The wide-temperature-resistant material maintains output stability by suppressing temperature-induced polarization attenuation. Under high-temperature conditions, the Curie temperature of the piezoelectric ceramic is raised to above 260℃, preventing abrupt changes in piezoelectric performance due to temperature increases.

[0070] Compared to existing technologies, traditional triaxial sensors often employ a parallel piezoelectric element layout, where signal output strength is limited by the sensitivity of individual elements, and crosstalk errors arise due to mechanical coupling between different axes. Existing piezoelectric materials typically operate below 150°C, and their performance is prone to degradation at high temperatures. This solution improves signal quality through a series structure, suppresses crosstalk through an orthogonal layout, and expands the applicable environmental range using wide-temperature materials.

[0071] Through the above technical solution, this application solves the problem of insufficient signal strength and cross-interference in multi-axial measurement, overcomes the defect of unstable performance of traditional sensors in extreme temperature environments, and realizes high-precision, low-crosstalk wide-temperature-range triaxial acceleration measurement.

[0072] This application further proposes that the lead sheet 5 has a square thin sheet (lead sheet body 51), a circular through hole in the middle (lead sheet screw mounting hole 52), and a rectangular protruding structure (sheet lead 53) on the top for leading out the test core wire.

[0073] The square sheet refers to a planar metal component with four equal sides and right angles. It can be formed by stamping a 0.1 mm thick beryllium bronze sheet, and its planar shape allows it to form surface contact with the mounting base 1 and the piezoelectric sensitive element 2. The circular through-hole refers to a through-hole structure located at the geometric center of the sheet, which can be achieved using a 2 mm diameter precision drilling process. This hole forms a clearance fit with the locking screw 4. The rectangular protruding structure refers to a strip-shaped platform extending upwards from the edge of the sheet. It can be formed into a 1.5 mm high three-dimensional structure using a stamping and bending process, and its length direction is parallel to the lead-out path of the test core wire.

[0074] Specifically, the square sheet is pressed between the mounting base 1 and the piezoelectric sensitive element 2 via planar contact, increasing the contact area by approximately 40% compared to the traditional circular lead sheet 5. This results in a uniform pressure distribution that avoids contact resistance fluctuations caused by localized deformation. The circular through-hole maintains a 0.05 mm gap with the locking screw 4 during assembly, creating physical isolation between the lead sheet 5 and the screw and eliminating the impact of parasitic capacitance generated by metal contact on signal transmission. The rectangular protruding structure forms a 0.8 mm wide guide groove, within which the test core wire is fixed by soldering. This structural constraint ensures that the core wire's displacement does not exceed 0.1 mm under axial vibration conditions.

[0075] Compared to existing technologies, traditional lead sheets often employ simple circular ring structures and lack directional lead designs. During miniaturization assembly, structural deformation can easily lead to poor contact, and the exposed core wires are susceptible to electromagnetic interference. This solution, through a triple structure combining planar contact, stress isolation, and directional constraint, improves signal transmission stability by approximately 60% within the same volume.

[0076] Through the above technical solution, this application solves the problem of lead wire reliability caused by limited internal space of micro sensors. By optimizing the geometric structure, it achieves precise positioning and stress isolation of the test core wire, and can maintain signal amplitude fluctuation of less than 3% when the vibration frequency reaches 10kHz. At the same time, it reduces the lead wire failure rate from the industry average of 5% to less than 0.8%.

[0077] This application further proposes that the middle part of the locking screw 4 is treated with hard black anodizing to ensure normal insulation performance between the positive and negative poles of the measuring structure, and the screw head 41 has an embedded mounting hole 45.

[0078] Hard black anodizing refers to a surface treatment technology that forms a dense aluminum oxide layer on a metal surface through an electrochemical process. Specifically, it can be achieved using a sulfuric acid electrolyte system in conjunction with a DC power supply. The oxide film formed by this process has high insulation and wear resistance.

[0079] The middle part of the locking screw 4 refers to the transition area 43 between the screw shank 42 and the threaded connection section (threaded area 44). Specifically, this can be achieved by limiting the oxidation treatment area to the central section of the shank. This area is located between the positive and negative conductive components after assembly.

[0080] Specifically, during the assembly of locking screw 4, the metal screw body may become the conductive medium between the positive and negative electrodes. By performing a hard black anodizing treatment on the central region, a uniformly thick aluminum oxide insulating layer is formed, blocking the current conduction path. The dielectric strength of the oxide film can withstand the sensor's operating voltage, and the hard treatment ensures that the oxide layer remains intact under the locking torque. Compared with ordinary anodizing, the black anodizing process can obtain a denser crystalline structure, further improving insulation reliability. This treatment method achieves electrical isolation through surface modification while maintaining the screw's mechanical strength.

[0081] Compared to existing technologies, traditional shear-type sensors often use plastic gaskets or sprayed insulating varnish to achieve screw insulation, but these methods suffer from drawbacks such as easy aging and assembly damage. This solution directly generates an insulating layer on the metal body, avoiding assembly errors associated with additional insulating components. Furthermore, the oxide layer exhibits higher bonding strength with the substrate and will not peel off under vibration conditions. The Vickers hardness of the hardened oxide layer can reach over 400 HV, significantly superior to the 250 HV level of ordinary anodizing processes.

[0082] Through the above technical solution, this application effectively blocks the parasitic conductive path formed between the positive and negative poles by the locking screw 4, eliminating signal crosstalk caused by metal contact. The wear-resistant properties of the oxide layer ensure the stability of insulation performance during long-term use, avoiding sensor output signal distortion or short-circuit faults. This design can maintain a stable electrical isolation state even under complex working conditions, providing a reliable signal transmission basis for triaxial acceleration measurement.

[0083] This application further proposes that the middle part of the locking screw 4 be treated with hard black anodizing.

[0084] Hard black anodizing refers to a surface modification technology that generates a dense aluminum oxide layer on the surface of aluminum alloy through an electrochemical process. Specifically, it can be achieved by using direct current electrolysis to form an oxide film with a thickness of 5-25 μm in the center of the screw. This oxide film has high resistivity and wear resistance. Normal insulation performance means that the resistance value between the metal parts is maintained at 10 ohms. 12 The insulation strength of the oxide film can reach 500~1000V / μm, which can be achieved by controlling the porosity and crystal morphology of the oxide film.

[0085] Specifically, during assembly, there is a risk of contact between the metal body of the locking screw 4 and the electrode of the piezoelectric sensitive element 2. To address this, a continuous and dense alumina insulating layer is formed in the middle of the screw through localized anodizing. When the screw is screwed into the mounting base 1, the oxide layer physically isolates the metal screw body from the surrounding conductive components, blocking potential leakage current paths. The oxide layer maintains structural integrity even under assembly torque, ensuring both fastening functionality and stable dielectric properties.

[0086] Compared to existing technologies, traditional solutions typically use plastic gaskets or insulating coatings for electrical isolation, but these suffer from insufficient mechanical strength and are prone to aging and detachment. This solution directly constructs an insulating layer on the surface of the metal fastener, avoiding assembly errors associated with additional insulating parts while maintaining the structural rigidity of the threaded connection. The metallurgical bond between the oxide layer and the substrate prevents delamination failure under vibration, thus overcoming the technical drawback of short lifespan in composite insulation structures.

[0087] Through the above technical solution, this application effectively blocks the parasitic conductive circuit formed by the locking screw 4 in the assembled state, increasing the insulation resistance value between the two poles of the piezoelectric sensitive element 2 by more than two orders of magnitude, and eliminating the risk of signal crosstalk and short circuit caused by metal contact. This insulation treatment method is integrated with the fastening structure, and can maintain stable dielectric properties even under long-term mechanical stress.

[0088] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

[0089] The working principle of this invention is: The bottom mounting thread hole of the mounting base 11 is screwed to the object to be measured by a universal mounting screw. When a vibration signal is input, the inertial mass block 3 moves relative to the mounting base 1, and the inertial force acts on the piezoelectric sensitive element 2. After being subjected to force, the piezoelectric sensitive element 2 generates a charge signal due to the piezoelectric effect. The charge signal is collected by the lead wire 5 and sent to the back-end circuit conversion and acquisition equipment to realize the acquisition of vibration signal.

[0090] The calibration data for the acceleration-sensitive structure in this embodiment are shown in the table below.

[0091]

[0092] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A miniature triaxial planar shear acceleration measurement sensing structure, characterized in that: It includes a mounting base (1) and three sets of mass-spring assemblies connected to the mounting base (1) in three directions by locking screws (4). The mass-spring assembly consists of a double-plate clamping structure and an inertial mass block (3) connected sequentially from the inside to the outside. The double-plate clamping structure consists of two piezoelectric sensitive elements (2) and a lead wire piece (5) clamped between the two piezoelectric sensitive elements (2). The mounting base (1) includes a mounting base body (11), a bottom threaded hole (12) connected to the bottom of the mounting base body (11) and extending upward, a hexahedron (13) connected to the top of the mounting base body (11), and a first threaded hole (14), a second threaded hole (15), and a third threaded hole (16) sequentially connected to the hexahedron (13) in three directions. The first threaded hole (14), the second threaded hole (15), and the third threaded hole (16) correspond to three measuring axes respectively, and are respectively threaded to the mass-spring assembly through the locking screw (4). The bottom surface of the mounting base body (11) is the mounting surface of the acceleration measurement sensitive structure, and the acceleration measurement sensitive structure is rigidly connected to the object being measured through the bottom threaded hole (12). The direction of the center of gravity vector of the acceleration measurement sensitive structure perpendicular to the mounting surface is in the same vertical plane as the axis of the bottom threaded hole (12), and the three sets of mass-spring assemblies can independently detect acceleration signals in three directions.

2. The miniature triaxial planar shear acceleration measurement sensing structure according to claim 1, characterized in that: The hexahedron (13) is a rectangular metal body with different lengths and widths. The first threaded hole (14) and the third threaded hole (16) are connected through each other and are both located in the long direction of the hexahedron (13). The second threaded hole (15) extends through the hexahedron (13). The bottom threaded hole (12) does not contact the first threaded hole (14), the second threaded hole (15) and the third threaded hole (16). The mounting base (1) also includes an isolation frustum structure (17) connecting the upper surface of the mounting base body (11) and the bottom of the hexahedron (13). The length and width of the upper part of the isolation frustum structure (17) are greater than the length and width of the bottom of the hexahedron (13). The isolated frustum structure (17) is a gradually sloping surface that is wide at the bottom and narrow at the top.

3. The miniature triaxial planar shear acceleration measurement sensitive structure according to claim 2, characterized in that: The isolated frustum structure (17) is a gradually changing slope with a height-to-bottom diameter ratio of 1:2 to 1:3; A transition plane is also connected between the top of the isolated frustum structure (17) and the bottom of the hexahedron (13); The bottom of the inertial mass block (3) is provided with a clearance groove to increase the gap between the bottom of the inertial mass block (3) and the isolated frustum structure (17).

4. The miniature triaxial planar shear acceleration measurement sensing structure according to claim 1, characterized in that: The inertial mass block (3) includes a mass block body (31), a notched structure (32) located at the rear of the inertial mass block (3), a wire outlet groove (33) connected to the upper part of the mass block body (31), and a mass block screw mounting hole (34) that passes through and connects to the mass block body (31). The notched structure (32) is a structure that forms an asymmetrical geometric shape by cutting the rear part of the inertial mass block (3) by oblique cutting or stepped cutting. The notched structure (32) reduces the material of the inertial mass block (3) to achieve volume reduction. The cable outlet groove (33) is a groove structure connected to the top of the inertial mass block (3); The lead sheet (5) includes a lead sheet body (51) with a sheet structure, a lead sheet screw mounting hole (52) connected to the center of the lead sheet body (51), and a sheet lead (53) connected to the top center of the lead sheet body (51) and extending upward. The width of the sheet lead (53) is smaller than the width of the lead sheet body (51). The lead sheet (5) is made of metal; After the acceleration measurement sensitive structure is assembled, the height of the sheet lead (53) is higher than that of the piezoelectric sensitive element (2) and the lead groove (33). The lead groove (33) allows the lead sheet (5) to be led from the side and connected to the signal wire at the external connection point.

5. The miniature triaxial planar shear acceleration measurement sensing structure according to claim 4, characterized in that: The signal wire and the motion plane of the inertial mass block (3) form a spatial perpendicular relationship, and the side wall of the outlet groove (33) forms a physical limit on the lead piece (5); The inertial mass block (3) is obtained by machining a tungsten alloy cube with a missing corner; The four sides of the lead sheet body (51) are of equal length and the included angle is a right angle. The length and width of the piezoelectric sensitive element (2) are greater than or equal to the length and width of the lead sheet body (51). The lead screw mounting hole (52) and the locking screw (4) are installed with a gap, and the diameter of the lead screw mounting hole (52) is larger than the outer diameter of the locking screw (4); The lead sheet (5) is made of gold-plated copper.

6. The miniature triaxial planar shear acceleration measurement sensing structure according to claim 1, characterized in that: The piezoelectric sensitive element (2) is a rectangular thin-film piezoelectric ceramic; In each set of the dual-plate clamping structures, the two piezoelectric sensitive elements (2) are connected in series by conductive adhesive or welding.

7. A miniature triaxial planar shear acceleration measurement sensitive structure according to claim 6, characterized in that: The piezoelectric sensitive element (2) is made of lead zirconate titanate-based ceramic material.

8. A miniature triaxial planar shear acceleration measurement sensing structure according to any one of claims 1 to 7, characterized in that: The locking screw (4) includes a screw head (41), a screw rod body (42), a transition area (43), a threaded area (44) connected in sequence, and an embedded mounting hole (45) connected inside the screw head (41). After the acceleration measurement sensitive structure is assembled, the outer surface of the screw head (41) is flush with the outer surface of the inertial mass block (3), the threaded area (44) is connected to the internal thread of the first threaded hole (14), the second threaded hole (15), or the third threaded hole (16), and the transition area (43) is located between the double-plate clamping structures. The transition zone (43) is oxidized to generate an insulating layer, preventing the locking screw (4) from forming a parasitic conductive circuit.

9. A miniature triaxial planar shear acceleration measurement sensitive structure according to claim 8, characterized in that: The transition zone (43) is subjected to hard black anodizing to generate an aluminum oxide insulating layer with a thickness of 5~25μm, and the Vickers hardness of the insulating layer is above 400HV. The locking screw (4) is made of titanium alloy.

10. A miniature triaxial planar shear acceleration measurement sensing structure according to claim 1, characterized in that: The assembly method of the acceleration measurement sensitive structure is as follows: When assembling each axis, first attach the piezoelectric sensitive element (2) in a set of mass-spring assemblies to one wall of the hexahedron (13), then place the lead wire piece (5) and align its through hole with the first threaded hole (14) or the second threaded hole (15) or the third threaded hole (16), then stack the second piezoelectric sensitive element (2) to form the double-piece clamping structure, finally install the inertial mass block (3) and apply axial preload by passing the inertial mass block (3), the second piezoelectric sensitive element (2), the lead wire piece (5), and the first piezoelectric sensitive element (2) through the locking screw (4) into the hexahedron (13) in sequence, and assemble the three sets of piezoelectric sensitive elements (2) in sequence. The three sets of piezoelectric sensitive elements (2) form independent mass-spring assemblies in the orthogonal direction. The measurement method of the acceleration measurement sensitive structure is as follows: when the object being measured vibrates, the shear force generated by the inertial mass block (3) acts on the piezoelectric sensitive element (2) to generate a charge signal proportional to the acceleration. The lead wire (5) is embedded between the two piezoelectric sensitive elements (2) to directly collect the charge and lead out the wire through the protruding end.

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