Piezoelectric acceleration and three-dimensional force composite sensor and assembling method thereof

Abstract

A piezoelectric acceleration and three-dimensional force composite sensor and an assembling method thereof belong to the technical field of composite sensors. The composite sensor comprises a base, a plurality of XY-axis force measuring modules are installed in the circumferential side wall of the base, a Z-axis force measuring module is installed in the interior of the base along the axial direction thereof, and the Z-axis force measuring module is coaxially connected with an acceleration detection module through a Z-axis force transmission rod. The XY-axis force measuring module comprises XY-axis force piezoelectric elements and XY-axis force electrode sheets which are alternately arranged along the force measuring direction, the innermost XY-axis force piezoelectric element is abutted with a leveling block, a spherical pit is arranged on the leveling block, a force transmission ball is arranged in the spherical pit, and the leveling block is abutted with the Z-axis force transmission rod through the force transmission ball. The acceleration detection and Z-axis force detection share the same force transmission reference and force transmission path, thereby improving the synchronism of dynamic measurement. The XY-axis force measuring module is matched with the force transmission ball and the spherical pit leveling block, thereby reducing the stress in other directions caused by the load direction deviation and reducing the mechanical cross talk between axes.

Description

Technical Field

[0001] This invention relates to the field of composite sensor technology, and in particular to a piezoelectric acceleration and three-dimensional force composite sensor and its assembly method. Background Technology

[0002] A composite sensor is a detection device that integrates the detection functions of two or more physical quantities into a single sensor, and can be used to simultaneously acquire multiple mechanical parameters of the object under test. In scenarios such as dynamic mechanics and impact testing, the object under test usually generates multi-directional forces and vibration accelerations simultaneously, so it is necessary to simultaneously detect three-dimensional forces and accelerations to obtain complete dynamic mechanical information.

[0003] Existing composite sensors typically have force-sensitive units and acceleration-sensitive units arranged in different directions within the same body. Each sensing unit transmits external loads to the piezoelectric element through a base, force transmission block, or force transmission rod. Among them, the multi-dimensional force-sensitive units are usually arranged in different directions, while the acceleration-sensitive units form an acceleration detection structure with the piezoelectric element through a mass block. The force detection module and the acceleration detection module each have relatively independent force transmission paths.

[0004] In existing composite sensor structures, when external loads are input in an inclined direction, the rigid force transmission interface can easily allow loads from non-target directions to enter other force measurement modules, causing inter-axis mechanical crosstalk. Furthermore, the force transmission paths of force measurement modules in different directions are interconnected, and external vibrations can easily be transmitted to other sensitive units through the main structure, affecting detection accuracy. In addition, the acceleration sensing module and the Z-axis force measurement module are usually set up separately, and their mechanical force transmission references are different, resulting in asynchronous responses between the acceleration signal and the Z-axis force signal. Summary of the Invention

[0005] To address the technical problem in the existing composite sensor structure described above, where the rigid force transmission interface easily allows loads from non-target directions to enter other force measurement modules when an external load is input in an inclined direction, causing mechanical crosstalk between shafts, this invention provides a piezoelectric acceleration and three-dimensional force composite sensor and its assembly method.

[0006] The technical solution of this invention is as follows: This invention provides a piezoelectric acceleration and three-dimensional force composite sensor, including a base with an external thread at the upper end. Several XY-axis force measuring modules are installed inside the circumferential sidewall of the base, and a Z-axis force measuring module is installed inside the base along its axial direction. The Z-axis force measuring module is coaxially connected to an acceleration detection module through a Z-axis force transmission rod. The XY-axis force measuring module includes XY-axis force piezoelectric elements and XY-axis force electrode plates alternately arranged along the force measuring direction. There are two XY-axis force piezoelectric elements and one XY-axis force electrode plate. The innermost XY-axis force piezoelectric element abuts against a leveling block. The leveling block has a spherical recess, and a force transmission ball is placed inside the spherical recess. The leveling block abuts against the Z-axis force transmission rod through the force transmission ball. The acceleration detection module and the Z-axis force measurement module are connected in series coaxially via a Z-axis force transmission rod, so that the acceleration detection and Z-axis force detection share the same force transmission reference and force transmission path. Structurally, this ensures that the dynamic response of the two is synchronized, eliminates the time phase difference caused by the difference in force transmission reference, and improves the synchronization of dynamic measurement. The XY-axis force measurement module uses a force transmission ball and a spherical concave leveling block to cooperate. When there is a deviation in the applied force, the force transmission ball can rotate adaptively relative to the spherical concave block, so that the deviated load is adjusted by the spherical contact before being transmitted to the XY-axis force piezoelectric element. This reduces the force in other directions caused by the deviation in the load direction and reduces mechanical crosstalk between axes.

[0007] Preferably, the circumferential sidewall of the base is provided with several sets of coaxially arranged first threaded holes, first cavities, and second cavities at intervals. The upper end of the base is provided with a third cavity, and the lower end of the base is provided with a second threaded hole. The third cavity and the second threaded hole are connected through a fourth cavity, which is also connected to the second cavity. The base is also provided with several wiring holes. The XY axis force measuring modules are arranged circumferentially in the sidewall cavities, and the Z axis force measuring module and the force transmission rod are arranged axially in the central cavity. The spatial layout is compact, and the installation reference of each module is uniform. The fourth cavity connects the Z axis cavity and the XY axis cavity, providing space for the force transmission ball and the Z axis force transmission rod to cooperate in force transmission. The wiring holes are used for centralized wiring, which can lead out the signal lines of each module in a unified manner, avoiding wiring interference with the force transmission structure, and improving electromagnetic shielding performance and protection level.

[0008] Preferably, a first insulating ring is provided in the first cavity, and the XY-axis force electrode plate and XY-axis force piezoelectric element are disposed within the first insulating ring. An XY-axis preload nut is threadedly connected to the first threaded hole. The outermost XY-axis force piezoelectric element abuts against the XY-axis preload nut through the XY-axis force transmission block. A leveling block is disposed in the first cavity, and a force transmission ball passes through the second cavity and abuts against the Z-axis force transmission rod. The first insulating ring forms an insulating enclosure and radial limit for the XY-axis piezoelectric element and electrode plate, ensuring that the force on the piezoelectric element is centered, while isolating the base from electrical interference with the sensitive element. The XY-axis preload nut, in conjunction with the force transmission block, can realize the preload adjustment of the XY-axis force measuring module, so that the piezoelectric element works in the optimal preload state, improving the force measuring sensitivity and linearity. The preload structure is arranged coaxially along the force measuring direction, and the preload is uniform, avoiding measurement errors introduced by off-center loading.

[0009] Preferably, the first insulating ring is provided with a through groove facing the wire hole, which facilitates the lead-out of the electrode plate signal line, avoids the wiring from squeezing the piezoelectric element, and at the same time ensures that the wiring is neat and reduces interference introduced by the vibration of the signal line.

[0010] Preferably, the Z-axis force measuring module includes a second insulating ring disposed within the third cavity. Z-axis piezoelectric elements and Z-axis force electrode plates are alternately arranged within the second insulating ring. The lowest Z-axis piezoelectric element abuts against a Z-axis force transmission block. One end of the Z-axis force transmission rod extends into the fourth cavity and abuts against the Z-axis force transmission block. A Z-axis preload nut is threadedly connected to a second threaded hole, used to push the Z-axis force transmission rod. The Z-axis force measuring module adopts a layered structure. The insulating ring ensures electrical insulation and radial positioning; the Z-axis force transmission block evenly transmits the load of the Z-axis force transmission rod to the piezoelectric element, resulting in uniform force distribution; the bottom Z-axis preload nut enables overall preload of the Z-axis module, with precise preload adjustment to ensure the linearity and sensitivity of Z-axis force detection; the coaxially arranged force transmission path ensures no off-center load and high measurement accuracy.

[0011] Preferably, the upper end of the Z-axis force transmission rod is hollow, and a first boss is provided on the upper end face of the Z-axis force transmission rod for limiting the Z-axis force transmission block; a third threaded hole is provided inside the upper end of the Z-axis force transmission rod; a fourth threaded hole is provided at the lower end of the Z-axis force transmission rod for connecting to external equipment; a second boss is fixedly provided on the outer peripheral wall of the Z-axis force transmission rod. The hollow upper structure provides built-in installation space for the acceleration detection module, realizing the coaxial integration of the acceleration module and the Z-axis force transmission rod, ensuring that the force transmission reference of the two is completely consistent; the first boss forms an axial limit on the Z-axis force transmission block, ensuring force transmission alignment; the third threaded hole is used for pre-tightening the acceleration module, which is convenient for installation and controllable for pre-tightening force; the fourth threaded hole at the lower end facilitates the connection of the sensor to the external measured structure; the second boss can form a force transmission limit and installation positioning reference, improving assembly accuracy.

[0012] Preferably, the acceleration detection module is located inside the upper end of the Z-axis force transmission rod. The acceleration detection module includes alternately arranged piezoelectric acceleration elements and acceleration electrode plates. A mass block is positioned above the uppermost piezoelectric acceleration element. The piezoelectric acceleration elements, acceleration electrode plates, and mass block are clamped together by a pre-tightening bolt, which is threadedly connected to a third threaded hole. The acceleration detection module is integrated internally within the Z-axis force transmission rod, resulting in a compact structure and complete coaxiality with the rod. Acceleration sensing and Z-axis force detection share the same force transmission path, ensuring completely synchronized dynamic responses with no phase difference. The layered piezoelectric structure, combined with the pre-tightening bolt, allows for precise adjustment of the pre-tightening force, resulting in high acceleration detection sensitivity and excellent frequency response characteristics. The built-in mass block prevents external interference and improves detection stability.

[0013] Preferably, a four-pin connector is installed on the upper end of the base. The four-pin connector is connected to the XY-axis force measurement module, Z-axis force measurement module, and acceleration detection module via signal lines. The four-pin connector outputs four signals: XY-axis force, Z-axis force, and acceleration. The interface has high integration and is convenient for field wiring.

[0014] Preferably, the base is circumferentially equipped with four sets of XY-axis force measuring modules. Two sets are arranged opposite each other along the X-axis, and two sets are arranged opposite each other along the Y-axis. The axes of the XY-axis force measuring modules in the X-axis and Y-axis directions are perpendicular to each other. The two oppositely arranged coaxial XY-axis force measuring modules use opposite electrode output polarities. The four sets of XY-axis force measuring modules are orthogonally arranged opposite each other along the X and Y directions, which can realize accurate detection of two-dimensional forces in the plane. At the same time, the opposite arrangement can cancel the influence of off-center load and improve the measurement accuracy. The opposite modules use opposite electrode output polarities to satisfy the superposition of their output amplitudes, effectively suppress common-mode interference, and improve the signal-to-noise ratio.

[0015] A method for assembling a piezoelectric accelerometer and a three-dimensional force composite sensor, comprising: First, install the acceleration detection module into the upper end of the Z-axis force transmission rod and keep it in a pre-tightened state; Then, the second insulating ring is installed in the third cavity, and the Z-axis force piezoelectric element, Z-axis force electrode plate and Z-axis force transmission block are installed in the second insulating ring, so that the upper end of the Z-axis force transmission rod cooperates with the Z-axis force transmission block, and then the whole is pre-tightened by the Z-axis pre-tightening nut. Install the corresponding XY axis force measuring modules in the circumferential direction of the base and pre-tighten them as a whole. The XY axis force measuring modules are connected to the Z axis force transmitting rod through force transmitting balls. Install a four-pin connector on the base, and gather the signal lines of the XY axis force measurement module, Z axis force measurement module and acceleration detection module through the wire hole to the four-pin connector.

[0016] First, the core acceleration module and the Z-axis force transmission rod are integrated and pre-tightened. Then, the Z-axis force measurement module is assembled. Finally, the XY-axis modules and interfaces are installed. The high coaxial alignment accuracy of each component ensures uniform pre-tightening force and unified force transmission benchmark for each module. The fit between the force transmission ball and the spherical recess can be automatically leveled, reducing the difficulty of assembly alignment and ensuring uniform force on each XY-axis module.

[0017] As can be seen from the above technical solutions, the advantages of the present invention are: The XY-axis force measurement module adopts a point-contact force transmission structure with a force-transmitting ball and a spherical concave leveling block. When the applied force is skewed, the force-transmitting ball can rotate adaptively relative to the spherical concave block, so that the skewed load is adjusted by the spherical contact before being transmitted to the XY-axis force piezoelectric element. This reduces the force in other directions caused by the load direction deviation and reduces mechanical crosstalk between axes. The acceleration detection module is directly installed inside the Z-axis force transmission rod, so that the acceleration detection module and the Z-axis force detection module have a common Z-axis mechanical force transmission reference. When the measured equipment is subjected to vibration or impact along the Z-axis direction, the Z-axis force is simultaneously transmitted to the Z-axis force piezoelectric element through the Z-axis force transmission rod and acts on the acceleration piezoelectric element set inside the Z-axis force transmission rod. This makes Fz and Az both respond based on the same Z-axis force transmission component, thereby reducing the mechanical transmission path difference caused by the separate setting of the force detection module and acceleration detection module in traditional composite sensors and improving the time correspondence between the Z-axis force signal and the Z-axis acceleration signal. Attached Figure Description

[0018] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of the piezoelectric acceleration and three-dimensional force composite sensor according to one or more embodiments of the present invention; Figure 2 This is a cross-sectional structural schematic diagram of the piezoelectric acceleration and three-dimensional force composite sensor according to one or more embodiments of the present invention; Figure 3 for Figure 2 A schematic diagram of the AA cross-sectional structure shown; Figure 4 This is a schematic diagram of the base according to one or more embodiments of the present invention; Figure 5 This is a cross-sectional structural diagram of the base according to one or more embodiments of the present invention; Figure 6 This is a structural schematic diagram of the XY axis force transmission block according to one or more embodiments of the present invention; Figure 7 This is a schematic diagram of the XY axis preload nut according to one or more embodiments of the present invention; Figure 8 This is a schematic diagram of the structure of the XY-axis force piezoelectric element according to one or more embodiments of the present invention; Figure 9This is a schematic diagram of the Z-axis preload nut according to one or more embodiments of the present invention; Figure 10 This is a schematic diagram of the Z-axis force transmission rod according to one or more embodiments of the present invention; Figure 11 This is a cross-sectional structural diagram of the Z-axis force transmission rod according to one or more embodiments of the present invention; Figure 12 This is a schematic diagram of the structure of an acceleration piezoelectric element according to one or more embodiments of the present invention; Figure 13 This is a schematic diagram of the structure of the acceleration electrode sheet according to one or more embodiments of the present invention; Figure 14 This is a schematic diagram of the mass block according to one or more embodiments of the present invention; Figure 15 This is a schematic diagram of the preload bolt according to one or more embodiments of the present invention; Figure 16 This is a schematic diagram of the structure of the first insulating ring according to one or more embodiments of the present invention; Figure 17 This is a schematic diagram of the structure of the XY-axis force electrode sheet according to one or more embodiments of the present invention; Figure 18 This is a schematic diagram of the leveling block according to one or more embodiments of the present invention; Figure 19 This is a cross-sectional structural diagram of the leveling block according to one or more embodiments of the present invention; Figure 20 This is a schematic diagram of the force-transmitting ball according to one or more embodiments of the present invention; Figure 21 This is a schematic diagram of the Z-axis force transmission block according to one or more embodiments of the present invention; Figure 22 This is a schematic diagram of the structure of the second insulating ring according to one or more embodiments of the present invention; Figure 23 This is a schematic diagram of the Z-axis force electrode sheet according to one or more embodiments of the present invention; Figure 24 This is a schematic diagram of the Z-axis force piezoelectric element according to one or more embodiments of the present invention; The components represented by the various reference numerals in the diagram are: 1. Four-core connector; 2. Base; 21. External thread; 22. First threaded hole; 23. First cavity; 24. Second cavity; 25. Wire hole; 26. Third cavity; 27. Fourth cavity; 28. Second threaded hole; 3. XY axis preload nut; 31. First force application hole; 4. XY axis force transmission block; 5. XY axis piezoelectric element; 6. Z axis preload nut; 61. Second force application hole; 7. Z axis force transmission rod; 71. First boss; 72. Third threaded hole; 73. Fourth threaded hole; 74. Second boss; 8. Acceleration piezoelectric element; 9. Acceleration electrode plate; 10. Mass block; 11. Preload bolt; 111. Third force application hole; 112. Screw part; 12. First insulating ring; 121. Through groove; 13. XY axis force electrode plate; 14. Leveling block; 141. Spherical pit; 15. Force transmission ball; 16. Z-axis force transmission block; 17. Second insulating ring; 18. Z-axis force electrode plate; 19. Z-axis force piezoelectric element. Detailed Implementation

[0020] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] Example 1 In a typical embodiment of the present invention, such as Figure 1 and Figure 2 As shown, a piezoelectric acceleration and three-dimensional force composite sensor is proposed, comprising: a four-pin connector 1, a base 2, an XY-axis preload nut 3, an XY-axis force transmission block 4, an XY-axis force piezoelectric element 5, a Z-axis preload nut 6, a Z-axis force transmission rod 7, an acceleration piezoelectric element 8, an acceleration electrode 9, a mass block 10, a preload bolt 11, a first insulating ring 12, an XY-axis force electrode 13, a leveling block 14, a force transmission ball 15, a Z-axis force transmission block 16, a second insulating ring 17, a Z-axis force electrode 18, and a Z-axis force piezoelectric element 19. The base 2 serves as the sensor body, and the four-pin connector 1 is detachably mounted on the upper end of the base 2 via a threaded connection. Figure 3 As shown, the four-pin connector 1 is used to output four detection signals: Fx, Fy, Fz, and Az; as Figure 4 and Figure 5As shown, the upper outer periphery of the base 2 is provided with an external thread 21 for connection with external testing equipment. The interior of the base 2 is provided with a first threaded hole 22, a first cavity 23, a second cavity 24, a wire hole 25, a third cavity 26, a fourth cavity 27 and a second threaded hole 28, so as to form the installation space for the XY axis force measuring module, the Z axis force measuring module and the acceleration detection module respectively.

[0022] Specifically, the first threaded hole 22, the first cavity 23, and the second cavity 24 are a group and coaxially arranged. The first threaded hole 22 communicates with the second cavity 24 through the first cavity 23. In this embodiment, four groups of first threaded holes 22, first cavities 23, and second cavities 24 are provided and opened on the circumferential sidewall of the base 2 for the installation of the XY axis force measuring module. A third cavity 26, a fourth cavity 27, and a second threaded hole 28 are each provided. The third cavity 26, the fourth cavity 27, and the second threaded hole 28 are coaxially arranged and communicate with each other. The third cavity 26 is located at the upper end of the base 2, the second threaded hole 28 is located at the lower end of the base 2, and the fourth cavity 27 is located at the middle position of the base 2. The fourth cavity 27 communicates with the second cavity 24. The third cavity 26 is used for the installation of the Z-axis force measuring module, and the fourth cavity 27 and the second threaded hole 28 are used for the installation of the acceleration detection module. Several wire holes 25 are provided and communicate with all the first cavities 23 for the wire harness to be threaded and led out.

[0023] In this embodiment, four sets of XY axis force measuring modules are arranged circumferentially on the base 2. The four sets of XY axis force measuring modules are arranged along the X-axis and Y-axis directions respectively. Two sets are arranged opposite each other along the X-axis direction, and two sets are arranged opposite each other along the Y-axis direction. The axes of the XY axis force measuring modules in the X-axis direction and the Y-axis direction are perpendicular to each other.

[0024] Each XY-axis force measuring module includes an XY-axis preload nut 3, an XY-axis force transmission block 4, an XY-axis force piezoelectric element 5, a first insulating ring 12, an XY-axis force electrode 13, a leveling block 14, and a force transmission ball 15. The first insulating ring 12 is disposed within the first cavity 23 and is used for positioning and electrically insulating the XY-axis force piezoelectric element 5 and the XY-axis force electrode 13. Figure 6 , Figure 8 and Figure 17 As shown, the XY-axis force transmission block 4, the XY-axis force piezoelectric element 5, and the XY-axis force electrode 13 are all circular structures. The XY-axis force piezoelectric element 5 and the XY-axis force electrode 13 are alternately arranged along the corresponding force measuring directions. There are two XY-axis force piezoelectric elements 5 and one XY-axis force electrode 13. The XY-axis force electrode 13 is located between the two XY-axis force piezoelectric elements 5 and is disposed within the first insulating ring 12. Figure 16As shown, the first insulating ring 12 has a through groove 121 facing the wire hole 25. The XY axis force transmission block 4 is located on the outside and abuts against the XY axis force piezoelectric element 5. The XY axis preload nut 3 is installed on the base 2 through the first threaded hole 22 and applies a preload force to the above components, such as... Figure 7 As shown, the XY axis preload nut 3 is provided with a first force application hole 31 to facilitate the application of preload force during assembly.

[0025] In the aforementioned XY-axis force measuring module, the leveling block 14 is disposed within the first cavity 23, and the leveling block 14 is positioned between the force transmission ball 15 and the innermost XY-axis piezoelectric element 5, as shown below. Figure 18 , Figure 19 and Figure 20 As shown, the leveling block 14 has a spherical recess 141 on the side facing the force transmission ball 15. The force transmission ball 15 is housed in the spherical recess 141 and forms a spherical fit with it. The force transmission ball 15 passes through the second cavity 24, and the side of the force transmission ball 15 away from the leveling block 14 contacts the Z-axis force measuring module. When an external force is input along the XY axis, the force is transmitted to the XY axis piezoelectric element 5 through the force transmission ball 15 and the leveling block 14. When the force is skewed, the force transmission ball 15 can rotate adaptively relative to the spherical recess 141, so that the skewed load is adjusted by the spherical contact before being transmitted to the XY axis piezoelectric element 5, thereby reducing the force in other directions caused by the load direction deviation and reducing inter-axis mechanical crosstalk. In this embodiment, the XY axis piezoelectric elements 5 in the two coaxial XY axis force measuring modules arranged oppositely use opposite electrode output polarities, so that the effective piezoelectric outputs in the same axis are superimposed, thereby improving the detection sensitivity and signal-to-noise ratio in the corresponding direction.

[0026] The base 2 is axially equipped with a Z-axis force measuring module, which includes a Z-axis preload nut 6, a Z-axis force transmission rod 7, a Z-axis force transmission block 16, a second insulating ring 17, a Z-axis force electrode plate 18, and a Z-axis force piezoelectric element 19, such as... Figure 21 , Figure 22 , Figure 23 and Figure 24As shown, the Z-axis force transmission block 16, the second insulating ring 17, the Z-axis force electrode plate 18, and the Z-axis force piezoelectric element 19 are all annular structures. The second insulating ring 17 is located inside the third cavity 26. The Z-axis force piezoelectric element 19 and the Z-axis force electrode plate 18 are alternately arranged inside the second insulating ring 17. There are two Z-axis force piezoelectric elements 19, and one Z-axis force electrode plate 18 is located between the two Z-axis force piezoelectric elements 19. The Z-axis force transmission block 16 abuts against the lowest Z-axis force piezoelectric element 19. One end of the Z-axis force transmission rod 7 extends into the fourth cavity 27 and abuts against the Z-axis force transmission block 16. The Z-axis preload nut 6 is threadedly connected to the second threaded hole 28. The Z-axis preload nut 6 is used to push the Z-axis force transmission rod 7, pressing the Z-axis force piezoelectric element 19, the Z-axis force electrode plate 18, and the Z-axis force transmission block 16 to form a stable Z-axis force transmission chain. Figure 9 As shown, the Z-axis preload nut 6 is provided with a second force application hole 61 for adjusting the preload during assembly. The second insulating ring 17 can position and electrically insulate the Z-axis force measuring component, thereby ensuring stable output of Z-axis force detection.

[0027] like Figure 10 and Figure 11 As shown, the Z-axis force transmission rod 7 includes a first boss 71, a third threaded hole 72, a fourth threaded hole 73, and a second boss 74. The upper end of the Z-axis force transmission rod 7 is hollow. The first boss 71 is located at the upper end face of the Z-axis force transmission rod 7 to form a mounting groove for limiting the Z-axis force transmission block 16. The third threaded hole 72 is opened inside the upper end of the Z-axis force transmission rod 7. The fourth threaded hole 73 is located at the lower end of the Z-axis force transmission rod 7 for connecting with external equipment. The second boss 74 is fixedly installed on the peripheral outer wall of the Z-axis force transmission rod 7 for cooperating with the Z-axis preload nut 6 for limiting.

[0028] Specifically, the Z-axis force transmission rod 7 serves as both the mounting and force transmission component for the acceleration detection module. Its upper end has a third threaded hole 72, and its lower end has a fourth threaded hole 73 for connection to external equipment. The second boss 74 bears the preload generated by the Z-axis preload nut 6. The acceleration detection module is located inside the upper end of the Z-axis force transmission rod 7. The acceleration detection module includes an acceleration piezoelectric element 8, an acceleration electrode 9, a mass block 10, and a preload bolt 11. Figure 12 , Figure 13 and Figure 14As shown, the accelerometer piezoelectric element 8, the accelerometer electrode 9, and the mass block 10 are all annular structures. The accelerometer piezoelectric element 8 and the accelerometer electrode 9 are alternately arranged inside the upper end of the Z-axis force transmission rod 7. There are two accelerometer piezoelectric elements 8 and one accelerometer electrode 9, with the accelerometer electrode 9 located between the two accelerometer piezoelectric elements 8. The mass block 10 is located above the uppermost accelerometer piezoelectric element 8. The accelerometer piezoelectric element 8, the accelerometer electrode 9, and the mass block 10 are tightened by a preload bolt 11. The preload bolt 11 includes a screw portion 112 and a third force application hole 111. The screw portion 112 is used for threaded connection with the third threaded hole 72. The mass block 10 is made of high-density material to improve inertial response. When the sensor vibrates along the Z-axis with the device under test, the mass block 10 generates an inertial force relative to the Z-axis force transmission rod 7, causing the accelerometer piezoelectric element 8 to be subjected to mechanical load and generate a corresponding charge signal, which is output by the accelerometer electrode 9.

[0029] Since the acceleration detection module is directly installed inside the Z-axis force transmission rod 7, the acceleration detection module and the Z-axis force detection module have a common Z-axis mechanical force transmission reference. When the device under test is subjected to vibration or impact along the Z-axis direction, the Z-axis force is simultaneously transmitted through the Z-axis force transmission rod 7 to the Z-axis force piezoelectric element 19, and acts on the acceleration piezoelectric element 8 set inside the Z-axis force transmission rod 7, so that Fz and Az both generate responses based on the same Z-axis force transmission component. This can reduce the mechanical transmission path differences caused by the separate setting of the force detection module and the acceleration detection module in traditional composite sensors, and improve the time correspondence between the Z-axis force signal and the Z-axis acceleration signal.

[0030] Example 2 In another typical embodiment of the present invention, a method for assembling a piezoelectric accelerometer and a three-dimensional force composite sensor is proposed, comprising: To assemble the piezoelectric acceleration and three-dimensional force composite sensor, firstly, place the acceleration piezoelectric element 8, acceleration electrode 9 and mass block 10 into the upper end of the Z-axis force transmission rod 7 in sequence, and screw the pre-tightening bolt 11 into the third threaded hole 72 to keep the above components in a pre-tightened state. Then, the second insulating ring 17 is installed in the third cavity 26 of the base 2, and then the Z-axis force piezoelectric element 19, Z-axis force electrode 18 and Z-axis force transmission block 16 are installed in the second insulating ring 17, so that the first boss 71 at the upper end of the Z-axis force transmission rod 7 cooperates with the Z-axis force transmission block 16, and then the whole is pre-tightened by the Z-axis pre-tightening nut 6. Finally, install the corresponding XY axis force measuring modules at each installation position around the base 2. Specifically, install the force transmitting ball 15 in the second cavity 24, and then install the first insulating ring 12 in the first cavity 23, so that the through groove 121 of the first insulating ring 12 faces the wire hole 25 of the base 2. Install the leveling block 14 in the corresponding first insulating ring 12, so that the spherical recess 141 cooperates with the force transmitting ball 15. After the leveling block 14 is installed in place, place the XY axis force piezoelectric element 5, XY axis force electrode 13 and XY axis force transmitting block 4 in the corresponding first insulating ring 12 in sequence. Install the XY axis preload nut 3 in the first threaded hole 22 and apply the preload force through the XY axis preload nut 3. Install a four-pin connector 1 on the base 2, and gather the signal lines of the XY axis force measurement module, Z axis force measurement module and acceleration detection module through the wire hole 25 to the four-pin connector 1 to form four outputs: Fx, Fy, Fz and Az.

[0031] In use, the sensor is connected to the device under test through the external thread 21 on the base 2 and the fourth threaded hole 73 on the Z-axis force transmission rod 7. When the device under test is subjected to three-dimensional forces and vibrations, the forces in the X-axis and Y-axis directions are transmitted to the XY-axis force piezoelectric element 5 through the corresponding force transmission ball 15, leveling block 14 and XY-axis force transmission assembly, respectively, forming Fx and Fy signals; the forces in the Z-axis direction are transmitted to the Z-axis force piezoelectric element 19 through the Z-axis force transmission rod 7, the first boss 71 and Z-axis force transmission block 16, forming Fz signal; at the same time, the vibration of the Z-axis force transmission rod 7 causes the mass block 10 to generate an inertial response, and the acceleration piezoelectric element 8 generates an Az signal, which is finally output through the four-core connector 1.

[0032] Through the above structure, this embodiment utilizes the spherical fit between the force transmission ball 15 and the spherical recess 141 to enable the XY-axis force measurement module to adapt to the force transmission posture of skewed loads, reducing mechanical crosstalk caused by loads in non-target directions. Through the circumferential partitioning and relative arrangement of the XY-axis force measurement module, the force transmission paths in different directions are separated from each other, and effective signal superposition is achieved by utilizing the opposite polarity of the relative cores. At the same time, the acceleration detection module is integrated into the Z-axis force transmission rod 7, so that acceleration detection and Z-axis force detection share the same mechanical force transmission reference. Thus, while realizing the synchronous detection of three-dimensional force and Z-axis acceleration, the mechanical coupling between different detection directions can be reduced, and the detection stability and signal quality under dynamic impact and vibration conditions can be improved.

[0033] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A piezoelectric acceleration and three-dimensional force composite sensor, comprising: The base (2) with an external thread (21) at the upper end is characterized in that a number of XY axis force measuring modules are installed in the circumferential sidewall of the base (2), and a Z axis force measuring module is installed in the interior of the base (2) along its axial direction. The Z axis force measuring module is coaxially connected to an acceleration detection module through a Z axis force transmission rod (7). The XY-axis force measuring module includes XY-axis force piezoelectric elements (5) and XY-axis force electrode plates (13) arranged alternately along the force measuring direction. There are two XY-axis force piezoelectric elements (5) and one XY-axis force electrode plate (13). The innermost XY-axis force piezoelectric element (5) abuts against a leveling block (14). The leveling block (14) has a spherical recess (141) and a force transmission ball (15) is placed in the spherical recess (141). The leveling block (14) abuts against the Z-axis force transmission rod (7) through the force transmission ball (15).

2. The piezoelectric acceleration and three-dimensional force composite sensor according to claim 1, characterized in that, The circumferential sidewall of the base (2) is provided with several sets of coaxially arranged first threaded holes (22), first cavities (23) and second cavities (24). The upper end of the base (2) is provided with a third cavity (26), and the lower end of the base (2) is provided with a second threaded hole (28). The third cavity (26) and the second threaded hole (28) are connected through a fourth cavity (27). The fourth cavity (27) is also connected to the second cavity (24). The base (2) is also provided with several wire holes (25).

3. The piezoelectric acceleration and three-dimensional force composite sensor according to claim 2, characterized in that, The first cavity (23) is provided with a first insulating ring (12), the XY axis force electrode plate (13) and the XY axis force piezoelectric element (5) are disposed in the first insulating ring (12), the first threaded hole (22) is threadedly connected to the XY axis preload nut (3), the outermost XY axis force piezoelectric element (5) abuts against the XY axis preload nut (3) through the XY axis force transmission block (4), the leveling block (14) is disposed in the first cavity (23), and the force transmission ball (15) passes through the second cavity (24) and abuts against the Z axis force transmission rod (7).

4. The piezoelectric acceleration and three-dimensional force composite sensor according to claim 3, characterized in that, The first insulating ring (12) has a through groove (121) facing the wire hole (25).

5. The piezoelectric acceleration and three-dimensional force composite sensor according to claim 2, characterized in that, The Z-axis force measuring module includes a second insulating ring (17) disposed in the third cavity (26). The second insulating ring (17) is alternately provided with Z-axis force piezoelectric element (19) and Z-axis force electrode plate (18). The lowest Z-axis force piezoelectric element (19) abuts against the Z-axis force transmission block (16). One end of the Z-axis force transmission rod (7) extends into the fourth cavity (27) and abuts against the Z-axis force transmission block (16). The second threaded hole (28) is threaded with a Z-axis preload nut (6). The Z-axis preload nut (6) is used to push the Z-axis force transmission rod (7).

6. The piezoelectric acceleration and three-dimensional force composite sensor according to claim 5, characterized in that, The upper end of the Z-axis force transmission rod (7) is hollow. A first boss (71) is provided on the upper end face of the Z-axis force transmission rod (7) for limiting the Z-axis force transmission block (16). A third threaded hole (72) is provided inside the upper end of the Z-axis force transmission rod (7). A fourth threaded hole (73) is provided at the lower end of the Z-axis force transmission rod (7) for connecting with external equipment. A second boss (74) is fixedly provided on the outer wall of the peripheral side of the Z-axis force transmission rod (7).

7. The piezoelectric acceleration and three-dimensional force composite sensor according to claim 6, characterized in that, The acceleration detection module is located inside the upper end of the Z-axis force transmission rod (7). The acceleration detection module includes alternating acceleration piezoelectric elements (8) and acceleration electrode plates (9). A mass block (10) is provided above the uppermost acceleration piezoelectric element (8). The acceleration piezoelectric element (8), acceleration electrode plate (9) and mass block (10) are pressed together by a preload bolt (11). The preload bolt (11) is threadedly connected to the third threaded hole (72).

8. The piezoelectric acceleration and three-dimensional force composite sensor according to claim 5, characterized in that, The upper end of the base (2) is equipped with a four-core connector (1), which is connected to the XY axis force measurement module, the Z axis force measurement module and the acceleration detection module through signal lines.

9. The piezoelectric acceleration and three-dimensional force composite sensor according to claim 1, characterized in that, The base (2) is provided with four sets of XY axis force measuring modules in the circumference. Two sets are arranged opposite each other along the X axis and two sets are arranged opposite each other along the Y axis. The axes of the XY axis force measuring modules in the X axis and Y axis are perpendicular to each other. The two XY axis force measuring modules arranged oppositely use opposite electrode output polarities.

10. A method for assembling a piezoelectric accelerometer and three-dimensional force composite sensor as described in any one of claims 5-8, characterized in that, include: First, the acceleration detection module is installed inside the upper end of the Z-axis force transmission rod (7) and kept in a pre-tightened state; Then, the second insulating ring (17) is installed in the third cavity (26), and the Z-axis force piezoelectric element (19), Z-axis force electrode plate (18) and Z-axis force transmission block (16) are installed in the second insulating ring (17) so that the upper end of the Z-axis force transmission rod (7) cooperates with the Z-axis force transmission block (16), and then the whole is pre-tightened by the Z-axis pre-tightening nut (6); The corresponding XY axis force measuring modules are installed circumferentially on the base (2) and pre-tightened as a whole. The XY axis force measuring modules abut against the Z axis force transmitting rod (7) through the force transmitting ball (15). Install a four-core connector (1) on the base (2) and gather the signal lines of the XY axis force measurement module, Z axis force measurement module and acceleration detection module through the wire hole (25) to the four-core connector (1).

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