Piezoelectric sensor and pavement weight measuring system

Abstract

The invention discloses a piezoelectric sensor and a pavement weight measuring system. The sensor comprises a shell and a piezoelectric wafer element, and an accommodating space is arranged in the shell; contact parts which are arranged in parallel are arranged on two sides of the accommodating space; the piezoelectric sensing element comprises a positioning component inserted in the accommodating space, a conducting strip is inserted in the positioning component, the upper part and the lower part of the conducting strip are respectively provided with a plurality of sensitive elements positioned by the positioning component, and every two sensitive elements in the vertical direction of the conducting strip correspond to each other in position; a transition plate for bearing is inserted between the sensitive element and the contact part; the transition plate is connected with the sensitive element through the conductive layer. The shell is designed to be an integrated aluminum alloy, the acting force of the shell acts on the quartz piezoelectric crystals through the transition plate, the conducting strip is arranged between the two quartz piezoelectric crystals at the same position, and due to the fact that the shell and the transition plate are usually made of steel plates and the quartz piezoelectric crystals are high in strength, the service life of the whole sensor is long.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle weighing, and in particular relates to a piezoelectric sensor and a road dynamic weighing system. Background Art

[0002] Overloaded vehicles pose a serious threat to the safety of road structures. They subject roads and bridges to forces exceeding their design loads, significantly increasing fatigue stresses and accelerating the accumulation of fatigue damage to highway and bridge structures. This damage is progressive and irreversible, ultimately leading to serious problems such as cracks and fractures on roads and bridges. Therefore, effective measures must be implemented to monitor and prevent overloaded vehicles from passing before vehicles enter bridges.

[0003] To achieve this goal, piezoelectric sensors and road weight measurement systems are widely used to measure vehicle weight. These sensors operate based on the piezoelectric effect, which occurs when a positioning component is subjected to mechanical stress and generates an electric charge on its surface. When a vehicle passes over the sensor, its weight exerts a vertical downward force on the sensor. This force is transmitted to the piezoelectric element through the sensor's load-bearing structure. The generated charge is collected by electrodes and converted into an electrical signal (voltage or charge). This signal is converted to a digital signal by an analog-to-digital converter and then processed by a microprocessor to ultimately calculate the weight of the object.

[0004] The design of the piezoelectric sensor and road weight measurement system is ingenious and complex. Its internal components utilize a double-layer conductive sheet as the positive and negative electrodes, with multiple quartz crystals positioned between the sheets to achieve the weighing function. The sensor's exterior is housed in a sturdy aluminum alloy housing, protected by an epoxy resin coating on the upper surface and elastic material on both sides. It is embedded in the ground to withstand the vehicle's weight. An insulating barrier is placed between the aluminum alloy housing and the transition plate to prevent electrical shorts and protect the internal components from external interference.

[0005] However, in practice, while the aluminum alloy housing can withstand most of the weight and pressure, the sensor itself still faces challenges. Existing quartz piezoelectric sensors experience repeated pressure shocks on the insulation layer during use, causing the impedance to gradually decay and the signal-to-noise ratio to decrease. After a certain period of time, the sensor becomes unable to collect valid data and fails. This signal interference can lead to inaccurate measurement data, seriously affecting the accuracy, stability, and reliability of vehicle weight detection. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention aims to provide a piezoelectric sensor and a road weighing system.

[0007] To achieve the aforementioned object of the invention, the technical solutions adopted by the present invention include: A piezoelectric sensor comprises a housing and a piezoelectric chip element, wherein a receiving space is provided in the housing; contact portions are arranged in parallel on both sides of the receiving space; The piezoelectric sensor element includes a positioning member inserted in the accommodating space, a conductive sheet is inserted in the positioning member, and a plurality of sensitive elements are provided on the upper and lower parts of the conductive sheet and positioned by the positioning member, and every two sensitive elements are positioned in a corresponding position in the vertical direction of the conductive sheet; A transition plate for bearing weight is inserted between the sensitive element and the contact portion; the transition plate is connected to the sensitive element through a conductive layer.

[0008] Preferably, in the aforementioned piezoelectric sensor, the radial cross-section of the transition plate used for connection with the housing is a plane or an arc-shaped surface.

[0009] Preferably, in the aforementioned piezoelectric sensor, the sensitive element is a quartz piezoelectric crystal.

[0010] Preferably, in the aforementioned piezoelectric sensor, the housing is an integrated aluminum alloy profile; the upper and lower side surfaces of the housing are parallel bearing parts; when the piezoelectric sensor is installed on the road surface, the bearing part and the contact part are both parallel to the road surface.

[0011] Preferably, the aforementioned piezoelectric sensor: a mounting groove for inserting a conductive sheet is opened in the middle of the component, a plurality of connecting holes for inserting sensitive elements are opened through the positioning component, the connecting holes are connected to the inside of the mounting groove, and a plurality of sensitive elements are respectively installed at both ends of the connecting holes at corresponding positions.

[0012] Preferably, in the aforementioned piezoelectric sensor, both sides of the shell are receiving tubes with arc-shaped cross-sections.

[0013] Preferably, in the aforementioned piezoelectric sensor, a wrapping layer is further provided on the outside of the shell, and the wrapping layer includes a grinding layer provided on the upper surface and an elastic layer located on other surfaces.

[0014] Preferably, the aforementioned piezoelectric sensor: the aforementioned piezoelectric sensor: the conductive layer and the transition plate are of separate design or the conductive layer is plated on the surface of the transition plate.

[0015] A road dynamic weighing system uses any of the piezoelectric sensors mentioned above. When two piezoelectric sensors are buried in the road surface, the two piezoelectric sensors are arranged in parallel and have an overlapping area, and the overlapping areas of the two piezoelectric sensors are connected in series.

[0016] Compared with the prior art, the advantages of the present invention include: The shell of the present invention is an integrated aluminum alloy design. The force of the shell acts on the quartz piezoelectric crystal through the transition plate. There is a conductive sheet between the two quartz piezoelectric crystals in the same position. Since the shell and the transition plate are usually made of steel plates and the strength of the quartz piezoelectric crystal is high, and there is only one conductive sheet and it is located in the middle position, it can be well protected, thereby extending the life of the entire sensor.

[0017] Compared with the prior art design of arranging conductive sheets on both sides of the conductive sheet and arranging an insulating layer between the conductive sheet and the shell, the present invention has only one conductive sheet and does not require an insulating layer between the conductive sheet and the shell, so the service life will be greatly extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is an overall schematic diagram of a piezoelectric sensor and a road weight measurement system in the present invention; Figure 2 Schematic diagram of the explosion effect of a piezoelectric sensor in the present invention Figure 3 Schematic diagram of the connection structure of the plane in the present invention; Figure 4 Schematic diagram of the connection structure of the arc surface in the present invention.

[0020] Reference numerals: 1. Housing; 11. Load-bearing part; 12. Accommodating tube; 14. Contact part; 2. Piezoelectric sensor element; 21. Positioning member; 22. Conductive sheet; 23. Transition plate; 25. Sensitive element; 26. Arc surface; 27. Mounting groove; 28. Connecting hole; 3. Conductive layer; 4. Elastic layer; 5. Grinding layer; 21a-Guarding edge. DETAILED DESCRIPTION

[0021] In view of the deficiencies in the prior art, the inventors of this case have proposed the technical solution of the present invention after long-term research and extensive practice. The following will further explain the technical solution, its implementation process and principles, etc. in conjunction with the drawings in the embodiments of this application and specific implementation cases.

[0022] It should be noted that the embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention. The embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, the present invention covers any substitution, modification, equivalent method and scheme made within the spirit, principle and scope of the present invention defined by the claims. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] like Figures 1 to 4 As shown, this embodiment discloses a piezoelectric sensor comprising a housing 1 and a piezoelectric chip element 2. The housing 1 has a housing space provided therein. Parallel contact portions 14 are provided on both sides of the housing space. The piezoelectric sensor element 2 includes a positioning member 21 inserted into the housing space. A conductive sheet 22 is inserted into the positioning member 21. Multiple sensitive elements 25 are provided above and below the conductive sheet 22, positioned by the positioning member 21. Each pair of sensitive elements 25 is positioned perpendicular to the conductive sheet 22. The sensitive elements 25 are quartz piezoelectric crystals.

[0024] A load-bearing transition plate 23 is inserted between the sensitive element 25 and the contact portion 14; the transition plate 23 is connected to the sensitive element 25 via the conductive layer 3. It should be noted that the conductive layer 3 and the transition plate 23 in this embodiment are designed as separate parts or the conductive layer 3 is plated on the surface of the transition plate 23. The transition plate 23 is usually a steel plate and is used to disperse the force between the contact portion 14 and the conductive sheet 22. The radial section of the transition plate 23 used to connect to the housing 1 is a flat surface 24 or an arcuate surface 26 ( Figure 4 The curved surface 26 can better disperse stress and avoid stress concentration, thereby improving the sensor's overall load-bearing capacity and service life. Curved surface 26 outperforms flat surface 24 in terms of explosion and impact resistance. Curved surface 26 can distribute impact forces over a larger area, reducing localized damage. Conductive layer 3 can utilize nickel strips, as is commonly used in the prior art.

[0025] The housing 1 is an integrated aluminum alloy profile; the upper and lower side surfaces of the housing 1 are parallel bearing portions 11 , and the two sides of the housing 1 are accommodating cylinders 12 with arc-shaped cross sections.

[0026] When the piezoelectric sensor is installed on the road surface, the bearing portion 11 and the contact portion 14 are both arranged parallel to the road surface.

[0027] A mounting slot 27 is defined in the center of the member 21 for inserting the conductive sheet 22. Multiple connection holes 28 are defined throughout the positioning member 21 for inserting the sensitive elements 25. These holes 28 communicate with the interior of the mounting slot 27, and the sensitive elements 25 are mounted at either end of the corresponding holes 28. Side ribs 21a are provided on either side of the positioning member 21. When the piezoelectric chip element 2 is inserted into the housing, these side ribs 21a engage the contact portion 14 and the transition plate 23, securing the piezoelectric chip element 2 within the housing 1.

[0028] When in use, the conductive sheet 22 and the housing 1 serve as two electrodes on both sides of the quartz piezoelectric crystal, wherein the housing 1 serves as the negative electrode and the conductive sheet 22 serves as the positive electrode.

[0029] Specifically, the bearing portion 11 includes a contact portion 14 integrally formed therewith, and the contact portion 14 contacts the transition plate 23. In this embodiment, the surface where the transition plate 23 contacts the contact portion 14 is a plane 24. The contact portion 14 is provided with a contact surface that matches the shape of the plane 24. The contact portion 14 contacts the plane 24 via the contact surface, and the contact surface of the contact portion 14 is equal in width to the plane 24.

[0030] In this embodiment, a wrapping layer is fixedly provided on both sides of the housing 1. The wrapping layer includes an abrasive layer 5 provided on the upper surface and an elastic layer 4 located on the other surfaces. The abrasive layer 5 is used to directly contact the vehicle tire. When the piezoelectric sensor is installed on the road surface, the abrasive layer 5 can be polished to make the top surface of the piezoelectric sensor level with the surrounding road surface, thereby avoiding a height difference between the piezoelectric sensor and the road surface after installation, thereby preventing the vehicle from jumping on the scale, and improving the detection accuracy of the piezoelectric sensor.

[0031] The material of the elastic layer 4 is mainly PE foam material, which is used to ensure the fit between the sensor and the building pavement to avoid loosening.

[0032] from Figure 2 It can be seen that the conductive sheet 22 is assembled in the middle of the positioning component 21, and the quartz crystal is installed in the connecting hole 28. The top and bottom of the component 21 are covered with transition plates 23, thereby forming a piezoelectric sensor element 2. The piezoelectric sensor element 2 is then inserted into the accommodating space in the housing 1. The space utilization rate of the overall assembly structure is very high, and the connection between the assembly structures is more fitting. During production, since the dimensional correlation between multiple structures is very high, the dimensional error in the production process can also be reduced.

[0033] In this embodiment, when the road surface is wide, the traditional installation method of the piezoelectric sensor and the road weighing system is to connect the ends of two piezoelectric sensors and the road weighing system to form a straight line for real-time vehicle weighing. However, when the wheel presses exactly on the connection between the two piezoelectric sensors and the road weighing system, data loss is likely to occur, resulting in greater vehicle weighing errors. To address this technical problem, this embodiment proposes the following solution: This embodiment also discloses a road weighing system. When two piezoelectric sensors and the road weighing system are embedded in the road surface, they are arranged in parallel with an overlapping region. The overlapping region of the two piezoelectric sensors and the road weighing system is then connected in series. Signals within the overlapping region are shielded, preventing inaccurate data from unstable signals at the end of a single sensor. This improves the accuracy of dynamic vehicle weighing, effectively intercepting overweight vehicles.

[0034] Compared with the existing technology, this embodiment uses an integrated aluminum alloy profile as the shell 1. The arc-shaped receiving tubes 12 on both sides of the shell 1 bear most of the road pressure, and only transmit a very small force to the conductive sheet 22, which greatly reduces the impact force of the vehicle on the conductive sheet 22 and improves the service life of the entire sensor.

[0035] The housing 1 in this embodiment is an integrated aluminum alloy design. The force of the housing 1 acts on the quartz piezoelectric crystal through the transition plate 23. There is a conductive sheet 22 between the two quartz piezoelectric crystals in the same position. Since the housing 1, the transition plate 23 (usually a steel plate) and the quartz piezoelectric crystals are relatively strong, and there is only one conductive sheet 22 located in the middle, they can be well protected, thereby extending the life of the entire sensor.

[0036] Compared with the prior art design in which conductive sheets 22 are arranged on both sides of the conductive sheet 22 and an insulating layer is arranged between the conductive sheet 22 and the housing 1, this embodiment has only one conductive sheet 22 and does not require an insulating layer to be designed between the conductive sheet 22 and the housing 1. Therefore, the service life of this embodiment will be greatly extended.

[0037] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can make some simple deductions or substitutions without departing from the concept of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A piezoelectric sensor, characterized in that: It comprises a housing (1) and a piezoelectric chip element (2); a receiving space is provided in the housing (1); and contact portions (14) are arranged in parallel on both sides of the receiving space; The piezoelectric sensor element (2) includes a positioning member (21) inserted into the accommodating space, a conductive sheet (22) is inserted into the positioning member (21), and a plurality of sensitive elements (25) positioned by the positioning member (21) are provided on the upper and lower parts of the conductive sheet (22), and each two of the sensitive elements (25) are positioned in a corresponding position in a vertical direction of the conductive sheet (22); A transition plate (23) for bearing weight is inserted between the sensitive element (25) and the contact portion (14); the transition plate (23) is connected to the sensitive element (25) via a conductive layer (3).

2. A piezoelectric sensor according to claim 1, characterized in that: The radial cross-section of the transition plate (23) for connection with the housing (1) is a plane (24) or an arcuate surface (26).

3. The piezoelectric sensor according to claim 1, wherein: The sensitive element (25) is a quartz piezoelectric crystal.

4. The piezoelectric sensor according to claim 1, wherein: The housing (1) is an integrated aluminum alloy profile; the upper and lower side surfaces of the housing (1) are parallel bearing portions (11); when the piezoelectric sensor is installed on a road surface, the bearing portion (11) and the contact portion (14) are both arranged parallel to the road surface.

5. A piezoelectric sensor according to claim 1 or 4, characterized in that: A mounting groove (27) for inserting the conductive sheet (22) is provided in the middle of the component (21), and a plurality of connection holes (28) for inserting the sensitive elements (25) are provided through the positioning component (21). The connection holes (28) are communicated with the interior of the mounting groove (27), and the plurality of sensitive elements (25) are respectively installed at both ends of the connection holes (28) at corresponding positions.

6. A piezoelectric sensor according to claim 1 or 4, characterized in that: On both sides of the housing (1) are accommodating cylinders (12) with arc-shaped cross sections.

7. A piezoelectric sensor according to any one of claims 1 to 4, characterized in that: The outer surface of the housing (1) is further provided with a wrapping layer, the wrapping layer comprising a grinding layer (5) arranged on the upper surface and an elastic layer (4) located on other surfaces.

8. The piezoelectric sensor according to claim 1, characterized in that: The conductive layer (3) and the transition plate (23) are of split design or the conductive layer (3) is plated on the surface of the transition plate (23).

9. A road surface dynamic weighing system, applied to the piezoelectric sensor according to any one of claims 1 to 8, characterized in that: When the two piezoelectric sensors are buried in the road surface, the two piezoelectric sensors are arranged in parallel and have an overlapping area, and the overlapping areas of the two piezoelectric sensors are connected in series.

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