High stiffness planar shear piezoelectric sensor

Abstract

The utility model provides a kind of high rigidity plane shear pressure electric sensor, including base and tightening stud, two pieces of side stand plate of relative setting are provided on the base, intermediate stand plate is provided between two piece side stand plate, the intermediate stand plate is parallel with side stand plate, piezoelectric assembly is provided between the intermediate stand plate and side stand plate, the tightening stud is in perpendicular to the direction of intermediate stand plate through two pieces of side stand plate, intermediate stand plate and piezoelectric assembly, locking nut is respectively provided in the axial both ends of the tightening stud to lock side stand plate, intermediate stand plate and piezoelectric assembly;Enhanced transverse tightening force, so that the connection between the first piezoelectric sheet, mass and second piezoelectric sheet is more closely, improves the transverse rigidity and resonance frequency of plane shear pressure electric sensor.

Description

Technical Field

[0001] This utility model relates to the field of sensor technology, specifically to a high-rigidity planar shear piezoelectric sensor. Background Technology

[0002] Piezoelectric sensors are a type of device based on the piezoelectric effect, capable of converting physical quantities such as force, pressure, and acceleration into electrical signals. Among them, the compression-type planar shear piezoelectric sensor is a suitable type of piezoelectric sensor for measuring in-plane vibration, shock, or dynamic forces, and is widely used in vibration measurement in fields such as industrial monitoring, predictive maintenance, automotive testing, and aerospace. The compression-type planar shear piezoelectric sensor uses a preload assembly (usually a stud and a pair of nuts at both ends of the stud) to press a mass block and a piezoelectric ceramic sheet together, causing them to move as a whole in the plane. This allows it to sense shear force or acceleration in the plane direction. The locking preload ensures that all components remain in close contact within the measurement range, increasing the rigidity of the entire sensor structure and making force transmission effective and smooth.

[0003] This structural technology is mature, economical, and easy to mass-produce. However, its stiffness is primarily determined by the series connection of the stud's tensile stiffness and the contact stiffness between components. This series connection results in relatively low stiffness, leading to a lower natural frequency. This prevents the sensor from accurately measuring high-frequency vibrations, limiting its detection range. Furthermore, the sensor's final preload is entirely determined by the torque of the locking nut. Torque is highly sensitive; even small changes in forces such as installation or impacts directly alter the contact stiffness and preload between components, causing differences in sensitivity among sensors produced in the same batch, thus affecting the shear force transmission efficiency. Additionally, when vibrations are perpendicular to the measurement direction (lateral), the mass will generate lateral inertial force. Due to the gap between the stud and the component hole, and the planar contact of the locking surface, this structure has low lateral constraint stiffness, making the mass prone to slight lateral swaying. This non-measurement direction movement couples to the measurement direction, generating interference signals and resulting in higher lateral sensitivity.

[0004] Therefore, it is necessary to improve the above-mentioned classic structure to overcome its insufficient stiffness in order to meet the needs of the ever-changing sensor market. Summary of the Invention

[0005] The purpose of this invention is to provide a high-rigidity planar shear piezoelectric sensor to solve the above-mentioned problems.

[0006] The technical solution adopted in this utility model is as follows: A high-rigidity planar shear piezoelectric sensor includes a base and a tightening stud. Two opposing side plates are disposed on the base, and a middle plate is disposed between the two side plates, parallel to the side plates. A piezoelectric assembly is disposed between the middle plate and the side plates. The tightening stud passes through the two side plates, the middle plate, and the piezoelectric assembly in a direction perpendicular to the middle plate. Locking nuts are respectively disposed at both axial ends of the tightening stud to lock the side plates, the middle plate, and the piezoelectric assembly.

[0007] As a further improvement of the present invention, the piezoelectric component includes a first piezoelectric sheet, a mass block, and a second piezoelectric sheet arranged in sequence, wherein the first piezoelectric sheet and the second piezoelectric sheet have the same structure.

[0008] As a further improvement of this utility model, a flexible insulating sleeve is provided on the tightening stud, and in the axial direction, the flexible insulating sleeve extends from one side plate to another side plate.

[0009] As a further improvement of the present invention, the cross-section of the side plate is trapezoidal, and the width of the base of the trapezoid near the middle plate is greater than the width of the other base of the trapezoid away from the middle plate.

[0010] As a further improvement of this utility model, the width of the force-bearing surface of the middle upright plate is greater than the width of the bottom edge of the side upright plate near the middle upright plate.

[0011] As a further improvement of the present invention, a plurality of intermediate upright plates are provided between the two side upright plates, and the plurality of intermediate upright plates are evenly distributed between the two side upright plates along the axial direction of the tightening stud, and a piezoelectric component is provided between two adjacent intermediate upright plates.

[0012] As a further improvement of the present invention, a connector assembly and a cable are also provided on the base. One end of the cable is connected to the connector assembly, and the other end of the cable leads out several branch lines that are connected to the mass blocks one by one.

[0013] As a further improvement of this utility model, there is a wiring gap between the bottom surface of the piezoelectric component and the top surface of the base, and the wiring gap is used for the installation of cables.

[0014] As a further improvement of this utility model, a wiring channel and a connector mounting hole are provided in the base. The wiring channel connects to the wiring gap, the cable is disposed in the wiring channel and the wiring gap, and the connector assembly is disposed in the connector mounting hole.

[0015] As a further improvement of the present invention, an upper cover is provided on the base, and the upper cover and the base cooperate to form an accommodating space. The middle upright plate, side upright plate, tightening stud, piezoelectric component and tightening nut are all arranged in the accommodating space, and a fixing hole is provided on the base.

[0016] The beneficial effects of this utility model are as follows: The above structure, which involves sequentially placing and locking the first piezoelectric sheet, the mass block, and the second piezoelectric sheet between the middle and side upright plates, enhances the lateral tightening force, making the connection between the first piezoelectric sheet, the mass block, and the second piezoelectric sheet tighter, thereby improving the lateral stiffness and resonant frequency of the planar shear piezoelectric sensor. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a high-rigidity planar shear piezoelectric sensor; Figure 2 This is a schematic diagram of the internal structure of a high-rigidity planar shear piezoelectric sensor; Figure 3 This is a cross-sectional view of a high-rigidity planar shear piezoelectric sensor along the axis of the tightening stud. Figure 4 This is a structural diagram of the base; Figure 5 This is a cross-sectional view of a high-stiffness planar shear piezoelectric sensor along the radial direction of the tightening stud.

[0018] Wherein: 101-base, 102-side plate, 103-middle plate, 104-wiring gap, 105-connector mounting hole, 106-wiring channel, 107-fixing hole, 2-tightening stud, 301-first piezoelectric piece, 302-mass block, 303-second piezoelectric piece, 4-locking nut, 5-through hole, 6-flexible insulating sleeve, 7-connector assembly, 701-connector housing, 702-conductive core, 703-insulating layer, 8-cable, 9-top cover. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the protection scope of the present invention.

[0020] If the description of this utility model involves directions (e.g., up, down, left, right, front, back, outside, inside, etc.), then the directions involved need to be defined. For example, "To clearly express the position and direction described in this utility model, the operator of the instrument is used as a reference, the end closer to the operator is the proximal end, and the end farther from the operator is the distal end." Or, the paper can be used as a reference. Of course, if the positional relationship between the two is defined by mutual reference in the subsequent description, then this definition is not required.

[0021] A high-stiffness planar shear piezoelectric sensor, such as Figures 1-3 As shown, the high-rigidity planar shear piezoelectric sensor includes a base 101 and a tightening stud 2. Two opposing side plates 102 are disposed on the base 101, and a middle plate 103 is disposed between the two side plates 102. The middle plate 103 is parallel to the side plates 102, and the two side plates 102 are symmetrically arranged on both sides of the middle plate 103. The middle plate 103 extends radially from the end face of the base 101, and the side plates 102 also extend radially from the end face of the base 101. A piezoelectric assembly is disposed between the middle plate 103 and the side plates 102. The tightening stud 2 is perpendicular to the middle plate 103. The tightening nut passes through two side plates 102, a middle plate 103, and a piezoelectric component. Specifically, the tightening nut passes sequentially through one side plate 102, one piezoelectric component, one middle plate 103, another piezoelectric component, and another side plate 102. Locking nuts 4 are respectively provided at both ends of the axial direction of the tightening stud 2 to lock the side plates 102, the middle plate 103, and the piezoelectric components, so that the side plates 102, the middle plate 103, and the piezoelectric components are tightly connected together. By clamping a set of piezoelectric components with the side plates 102 and the middle plate 103, the rigidity of the planar shear piezoelectric sensor is enhanced, and the resonant frequency of the planar shear piezoelectric sensor is increased.

[0022] In one embodiment of this utility model, the piezoelectric assembly includes a first piezoelectric piece 301, a mass block 302, and a second piezoelectric piece 303 arranged sequentially, with the first piezoelectric piece 301 and the second piezoelectric piece 303 having the same structure. After assembling the tightening stud 2, the first piezoelectric piece 301, the mass block 302, and the second piezoelectric piece 303, tightening the locking nuts 4 at both ends applies pressure to the first piezoelectric piece 301, the mass block 302, and the second piezoelectric piece 303 from the side plate 102 to the middle plate 103, tightly fixing the side plate 102, the middle plate 103, and the first piezoelectric piece 301, the mass block 302, and the second piezoelectric piece 303 located between them together, thereby increasing the stiffness and resonant frequency of the piezoelectric sensor.

[0023] To provide a channel for the tightening stud 2, such as Figure 3 ,4 As shown, coaxial through holes 5 are provided on the side plate 102, the middle plate 103, the first piezoelectric piece 301, the mass block 302, and the second piezoelectric piece 303. The through holes 5 have the same diameter and form an installation channel for the tightening stud 2 to pass through. A flexible insulating sleeve 6 is provided in the installation channel and is sleeved on the tightening stud 2. In the axial direction, the flexible insulating sleeve 6 extends from one side plate 102 to another side plate 102. The flexible insulating sleeve 6 is used to form electrical insulation between the side plate 102 and the tightening stud 2, and between the middle plate 103 and the tightening stud 2, thereby achieving insulation between the mass block 302 and the base 101 (including the side plate 102 and the middle plate 103 located on the base 101).

[0024] As one embodiment of this utility model, such as Figure 4 As shown, the side plate 102 has a trapezoidal cross-section, which is a section perpendicular to the extension direction of the side plate 102 relative to the base 101. This trapezoid is isosceles, with its two bases perpendicular to the axis of the tightening stud 2. The width of the base closer to the middle plate 103 is greater than the width of the other base farther from the middle plate 103. For ease of description, these two bases will be referred to as the long base and the short base. Increasing the contact area between the side plate 102 and the first piezoelectric piece 301 reduces pressure and disperses the force, preventing damage to the first piezoelectric piece 301. When tightening force is applied from the short base, the force is decomposed by the trapezoidal slope of the side plate 102, making it easy to control. Simultaneously, the trapezoidal slope of the side plate 102 guides the first piezoelectric piece 301 to the center position during tightening, enhancing positioning and tightening effects. Correspondingly, the cross-section of the intermediate upright plate 103 is rectangular, serving as a fixed reference plane for the tightening action. The rectangular cross-section is regular in shape, easy to process and install. When the rectangular cross-section intermediate upright plate 103 is combined with the trapezoidal cross-section side upright plate 102, a tightening force is applied from the short base direction. The intermediate upright plate 103 remains flat, ensuring stability during clamping. Alternatively, the cross-section of the side upright plate 102 can be approximately trapezoidal, with the waist of the approximately trapezoid being an outwardly convex arc.

[0025] In one embodiment of this utility model, the width of the force-bearing surface of the intermediate upright plate 103 is greater than the width of the bottom edge of the side upright plate 102 near the intermediate upright plate 103. Correspondingly, the area of ​​the side upright plate 102 in contact with the first piezoelectric sheet 301 can be close to the area of ​​the first piezoelectric sheet 301, and the area of ​​the intermediate upright plate 103 is greater than the area of ​​the intermediate upright plate 103 in contact with the second piezoelectric sheet 303. This can disperse the pressure, avoid damage to the second piezoelectric sheet 303, and also apply a uniform force to the second piezoelectric sheet 303, improving the tightening stability and the anti-overturning ability during the force application process.

[0026] As an embodiment of this utility model, when the sensitivity of the entire planar shear piezoelectric sensor needs to be improved, the following technical solution can be adopted: A plurality of intermediate upright plates 103 are arranged between the two side upright plates 102, and the intermediate upright plates 103 are linearly and evenly distributed along the axial direction of the tightening stud 2 between the two side upright plates 102. A piezoelectric component is arranged between adjacent intermediate upright plates 103. By adding the piezoelectric component and the intermediate upright plates 103 in this way, the decrease in operating frequency can be avoided. According to the resonant frequency formula: Where f represents the resonant frequency, k represents the system stiffness, and m represents the moving mass, which includes the weight of the mass block 302 and the piezoelectric sheet. If only the mass block and piezoelectric sheet are added, the resonant frequency f will tend to decrease as the moving mass m increases, the maximum operating frequency of the planar shear piezoelectric sensor will decrease, and the bandwidth will narrow. Therefore, in this embodiment, an intermediate vertical plate 103 is added to cooperate with the addition of the piezoelectric component. The piezoelectric component is clamped by the two intermediate vertical plates 103 to improve the system stiffness k and compensate for the increase in moving mass m. Thus, the resonant frequency f can be increased while the sensitivity of the piezoelectric sensor does not decrease.

[0027] As one embodiment of this utility model, such as Figure 4 , 5 As shown, a connector mounting hole 105 is provided in the base 101, and a connector assembly 7 is provided in the connector mounting hole 105. The connector assembly 7 extends out of the base 101 from the side, and a cable 8 is provided between the connector assembly 7 and the mass block 302 for connection. The connector assembly 7 is used to provide a protected path to transmit the weak charge or high impedance voltage signal generated inside the piezoelectric sensor to an external device.

[0028] Correspondingly, such as Figure 3As shown, a wiring gap 104 exists between the bottom surface of the piezoelectric assembly and the top surface of the base 101. Specifically, the bottom surfaces of the first piezoelectric piece 301, the mass block 302, and the second piezoelectric piece 303 all have wiring gaps 104 with the top surface of the base 101. These wiring gaps 104 are used to accommodate the cable 8. Furthermore, the first piezoelectric piece 301, the mass block 302, and the second piezoelectric piece 303 can have the same height and flush bottom surfaces.

[0029] Correspondingly, such as Figure 4 , 5 As shown, a wiring channel 106 is provided in the base 101, the wiring channel 106 connects to the wiring gap 104, and the cable 8 is disposed in the wiring channel 106 and the wiring gap 104.

[0030] Specifically, such as Figure 5 As shown, the connector assembly 7 includes a connector housing 701. Inside the connector housing 701, a conductive core 702 and an insulating layer 703 are sequentially arranged from the inside out. One end of the cable 8 is connected to the conductive core 702, and the other end of the cable 8 extends into several branches that connect to the mass block 302. The connector assembly 7 extends from the side of the base 101 to facilitate connection with external devices, such as a vibration sensor. The cable 8 conducts the charge generated by the first piezoelectric plate 301 and the second piezoelectric plate 303 through the mass block 302 to the conductive core 702, and finally to the external device through the external cable 8.

[0031] like Figure 5 As shown, an upper cover 9 is provided on the base 101. The upper cover 9 and the base 101 cooperate to form an accommodating space. The middle upright plate 103, side upright plate 102, tightening stud 2, tightening nut, first piezoelectric plate 301, mass block 302 and second piezoelectric plate 303 are all disposed within this accommodating space. The upper cover 9 protects the internal components while improving the airtightness and electromagnetic shielding performance of the planar shear piezoelectric sensor. A fixing hole 107 is provided on the side of the base 101 away from the upper cover 9. The fixing hole 107 is used to fix the base 101 with external fasteners.

[0032] The high-rigidity planar shear piezoelectric sensor provided by this utility model enhances the lateral tightening force by sequentially arranging the first piezoelectric piece 301, the mass block 302, and the second piezoelectric piece 303 between the intermediate upright plate 103 and the side upright plate 102, and then locking them with the tightening stud 2 and nut. This makes the connection between the first piezoelectric piece 301, the mass block 302, and the second piezoelectric piece 303 tighter, thereby improving the lateral stiffness of the planar shear piezoelectric sensor and increasing its resonant frequency.

[0033] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0034] The detailed descriptions listed above are merely specific descriptions of feasible implementation methods of this utility model, and are not intended to limit the scope of protection of this utility model. All equivalent implementation methods or modifications made without departing from the spirit of this utility model should be included within the scope of protection of this utility model.

Claims

1. A high-stiffness planar shear piezoelectric sensor, characterized in that: The device includes a base (101) and a tightening stud (2). Two side plates (102) are arranged opposite to each other on the base (101). An intermediate plate (103) is arranged between the two side plates (102). The intermediate plate (103) is parallel to the side plates (102). A piezoelectric assembly is arranged between the intermediate plate (103) and the side plates (102). The tightening stud (2) passes through the two side plates (102), the intermediate plate (103) and the piezoelectric assembly in a direction perpendicular to the intermediate plate (103). Locking nuts (4) are respectively arranged at both ends of the tightening stud (2) to lock the side plates (102), the intermediate plate (103) and the piezoelectric assembly.

2. The high-stiffness planar shear piezoelectric sensor according to claim 1, characterized in that: The piezoelectric assembly includes a first piezoelectric sheet (301), a mass block (302), and a second piezoelectric sheet (303) arranged in sequence, with the first piezoelectric sheet (301) and the second piezoelectric sheet (303) having the same structure.

3. The high-stiffness planar shear piezoelectric sensor according to claim 2, characterized in that: A flexible insulating sleeve (6) is fitted on the tightening stud (2). In the axial direction, the flexible insulating sleeve (6) extends from one side plate (102) to another side plate (102).

4. The high-stiffness planar shear piezoelectric sensor according to claim 2, characterized in that: The side panel (102) has a trapezoidal cross-section, and the width of the base of the trapezoid near the middle panel (103) is greater than the width of the other base of the trapezoid away from the middle panel (103).

5. The high-stiffness planar shear piezoelectric sensor according to claim 4, characterized in that: The width of the force-bearing surface of the intermediate upright plate (103) is greater than the width of the bottom edge of the side upright plate (102) near the intermediate upright plate (103).

6. The high-stiffness planar shear piezoelectric sensor according to claim 4, characterized in that: A plurality of intermediate plates (103) are provided between the two side plates (102), and the plurality of intermediate plates (103) are evenly distributed between the two side plates (102) along the axial direction of the tightening stud (2), and a piezoelectric assembly is provided between two adjacent intermediate plates (103).

7. The high-stiffness planar shear piezoelectric sensor according to claim 2, characterized in that: A connector assembly (7) and a cable (8) are also provided on the base (101). One end of the cable (8) is connected to the connector assembly (7), and the other end of the cable (8) leads out several branch lines to connect to the mass block (302).

8. The high-stiffness planar shear piezoelectric sensor according to claim 7, characterized in that: There is a wiring gap (104) between the bottom surface of the piezoelectric component and the top surface of the base (101), which is used for the placement of the cable (8).

9. The high-stiffness planar shear piezoelectric sensor according to claim 8, characterized in that: A wiring channel (106) and a connector mounting hole (105) are provided in the base (101). The wiring channel (106) connects to the wiring gap (104). The cable (8) is disposed in the wiring channel (106) and the wiring gap (104). The connector assembly (7) is disposed in the connector mounting hole (105).

10. The high-stiffness planar shear piezoelectric sensor according to claim 1, characterized in that: An upper cover (9) is provided on the base (101). The upper cover (9) and the base (101) cooperate to form an accommodating space. The middle upright plate (103), the side upright plate (102), the tightening stud (2), the piezoelectric component and the tightening nut are all provided in the accommodating space. A fixing hole (107) is provided on the base (101).

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