Tension sensor

Abstract

The utility model relates to a tension sensor, which comprises a base, an elastic element, an upper cover plate and a detection circuit, the elastic element is arranged on the top surface of the base, a resistance strain gauge is pasted on the surface of one longitudinal side or two longitudinal sides of the elastic element, bearing plates extending upwards are arranged at the left end and the right end of the top surface of the elastic element, and lower grooves transversely penetrating through the bearing plates are formed in the tops of the bearing plates. The upper cover plate and the base are in threaded connection through bolts, the detection circuit adopts a Huygens bridge, and the resistance strain gauge forms a bridge arm of the Huygens bridge. The tension sensor can better adapt to the field condition of the slope protection net, the detection accuracy is improved, and the tension sensor is convenient to install and use.

Description

Technical Field

[0001] The utility model relates to a tension sensor, which is mainly suitable for monitoring stress changes of a protection net. Background Art

[0002] The protective net used for slope protection such as hillsides and river banks is usually fixed on the outside of the slope with anchor rods and support ropes (usually steel wire ropes). It is used in places where there are risks of geological disasters such as slope collapse and weathering and peeling to achieve slope reinforcement and protection. When setting up, the flexible net is pre-tensioned by supporting ropes or steel wire mesh or prestressed anchor rods. During use, by monitoring the tension of the protective net and the stress changes of the steel wire rope, changes in the slope state and the risk of slope collapse can be discovered in time, and early warnings can be issued.

[0003] At present, elastic tensioners are usually used to monitor the tension state of the protective net. The elastic tensioners are connected in series to the main cable (or support rope) of the protective net. The tension applied to the main cable can be directly detected by detecting the tension applied to the sensor element by the degree of stretching. For example, Chinese patent document CN219860099U discloses a conveying device for assembled building blocks, including a winch, an arc-shaped rubber pressure block and a tension sensor. The winch is provided with a wire rope assembly. The tension sensor is installed at the bottom of the wire rope assembly. A connector is installed at the bottom of the tension sensor. Connecting ropes are fixed on both sides of the connector. A conveying frame is installed between adjacent connecting ropes. The tension sensor can monitor the force applied to the device in real time. When the assembled building blocks with larger specifications to be conveyed are too heavy, the control device connected to the device will control the buzzer alarm to sound an alarm, thereby enabling the device to achieve a better overload warning function and improve the safety effect of the device. Chinese patent document CN205992879U discloses a dual-motor soft-rope traction type solar tracking bracket drive system, including a driving beam, a first tension sensor is installed at one end of the driving beam, the driving beam is connected to the left support and the right support of the bracket through a rotating shaft, a first driving device is installed on the left support of the bracket, the first driving device is connected to the first tension sensor through a first soft rope, a second driving device is installed on the right support of the bracket, the second driving device is connected to the end of the driving beam away from the first tension sensor through a second soft rope, and both the first driving device and the second driving device are connected to the controller through wires. Chinese patent document CN109884112A discloses a soil frost heave detection device and detection method without external power supply, wherein a casing is provided on the chassis, an upper anchor plate is fixedly connected to the upper end of the casing, an elastic member is arranged in the casing, a force-bearing end of the tension sensor passes through the upper anchor plate and is connected to one end of the elastic member, and the other end of the elastic member is connected to the chassis through a connecting rod, and the frost heave data of the frost heave layer at each measuring point in different periods are obtained through the soil frost heave detection device, and the frost heave deformation of the frozen soil in the test area is obtained according to the frost heave data fed back from each measuring point. However, although such tension sensors can directly detect the tensile stress / tension condition of steel wire ropes, etc., due to the limitations of the use conditions, if applied to slope protection nets, they often need to be made relatively bulky, and relatively harsh on-site installation conditions are required to ensure accurate measurement. After long-term use, due to changes in the conditions of the protection net or slope, large detection errors are prone to occur. Utility Model Content

[0004] The purpose of the utility model is to better adapt to the on-site conditions of the protective net, improve the accuracy of detection, and facilitate installation and use.

[0005] The technical solution of the utility model is: a tension sensor, comprising:

[0006] A base having a top surface;

[0007] The elastic element is arranged on the top surface of the base, and a resistance strain gauge is pasted on one or both sides of the longitudinal surface of the elastic element. The left and right ends of the top surface of the elastic element are provided with pressure plates extending upward, and the top of the pressure plate (usually the longitudinal center of the top) is provided with a lower groove (or notch) that runs through the pressure plate horizontally;

[0008] The upper cover plate is located above the elastic element, and its lateral dimension is smaller than the lateral spacing (interval) between the two pressure-bearing plates, and / or a convex structure (usually in the shape of a longitudinally extending cylinder) is provided in the lateral middle of its bottom surface, and the lateral dimension of the convex structure is smaller than the lateral spacing between the two pressure-bearing plates;

[0009] The bolt is used to realize the threaded connection between the upper cover plate and the base, and the two ends of the bolt are respectively connected to the upper cover plate and the base, wherein at least the connection mode between the upper cover plate or the base is a threaded connection.

[0010] Preferably, the main body of the elastic element is in the shape of a rectangular parallelepiped.

[0011] Optionally, the pressure-bearing plate is integrated with the main body of the elastic element; or, the bottom surface of the pressure-bearing plate is fixedly connected to the top surface of the main body of the elastic element.

[0012] Optionally, the bottom surface of the upper cover plate is provided with or without an upper groove structure. The number of the upper groove structure can be one, which runs through the bottom surface of the upper cover plate; or the number of the upper groove structure is two, which are respectively located at the two ends of the bottom surface of the upper cover plate, extending downward from the bottom surface of the upper cover plate, and the bottom is provided with an upper groove.

[0013] Preferably, there are two bolts, which are located in the middle in the transverse direction and at the front and rear sides in the longitudinal direction.

[0014] Preferably, the lower end of the bolt is fixedly connected to the base (it can be a threaded connection or a non-threaded connection, for example, welding), the top is provided with an external thread, and the upper cover is provided with light holes corresponding to each bolt, and the top of the bolt passes through the corresponding light hole on the upper cover and is screwed with a fastening nut.

[0015] Preferably, the bolt is provided with an upper limit nut and with or without a lower limit nut. The upper limit nut is located below the upper cover plate to form a limit structure of the upper cover plate, and the lower limit nut is located above the base to form a limit structure of the base.

[0016] Typically, the resistance strain gauge may be in the form of a sheet bonded to the corresponding surface of the elastic element.

[0017] Furthermore, a detection circuit is provided, and a resistance strain gauge is connected to the detection circuit and serves as a resistive sensing element of the detection circuit.

[0018] Preferably, the detection circuit adopts a Huygens bridge, and the resistance strain gauge is connected in series to one arm of the Huygens bridge to form one arm of the Huygens bridge.

[0019] When there are multiple resistance strain gauges, the multiple resistance strain gauges are connected to the same bridge arm of the Huygens bridge and can be connected in series or in parallel, etc., which can be specifically set according to the characteristics of the Huygens bridge and the resistance strain gauge and the detection requirements.

[0020] Preferably, the Huygens bridge is arranged at one lateral end of the elastic element and is provided with a wiring terminal for outputting a detection voltage.

[0021] The beneficial effects of the utility model are as follows: since the sensing element adopts a double-hole shear beam structure, the tension of the main cable (support rope) is converted into vertical (perpendicular to the direction of the base or the installation base surface) pressure and the shear stress of the elastic element, which significantly reduces the detection error caused by changes in external conditions such as the protection net or the slope condition, and its force-bearing mode and measurement accuracy basically do not change significantly due to long-term use, thereby improving and ensuring the detection accuracy and improving the long-term stability; since the resistance strain gauge on the elastic element converts the strain proportional to the tension of the wire rope into a resistance change, the resistance change of the resistance strain gauge can be converted into a voltage output through a circuit such as a Wheatstone bridge, and the measured voltage output value can be converted into a corresponding force value through a digital display instrument to complete the measurement and metering task; due to its light weight, the base is supported and arranged on the slope covered by the protection net, and there is no need to destroy or change the original state and connection method of the wire rope during installation, which greatly facilitates on-site installation and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the utility model (main viewing direction);

[0023] Figure 2 It is a schematic diagram of the structure of the utility model (side view);

[0024] Figure 3 It is a schematic diagram of the structure of the utility model (viewed from above);

[0025] Figure 4 This is the detection principle diagram of the utility model (main viewing direction);

[0026] Figure 5 It is a schematic diagram of the on-site layout of the utility model. DETAILED DESCRIPTION

[0027] See also Figures 1 to 5This tension sensor is provided with an upper cover plate (or top plate) 4, a bottom plate (or lower cover plate) 1 and an elastic element (elastic body) 2. The main part of the elastic element can be a rectangular solid (or a cuboid), and its long edges can usually be set in the horizontal direction, used as a pressure sensing element, and a resistance strain gauge (sheet) 5 is bonded (pasted) on one or both sides of its longitudinal (front-to-back direction) surface. Both lateral ends of the top surface (upper surface) of the elastic element are provided with pressure plates (or pressure blocks) 3 extending upward. The pressure plate can be an independent part fixedly mounted (for example, bonded) on the elastic element, or it can be integrated with the main part of the elastic element. A lower groove (usually a circular arc groove) 10 is provided in the middle of the top of the pressure plate, which runs through the pressure plate horizontally. A groove structure corresponding to the lower groove on the top of the pressure plate can be provided on the upper cover (see Figure 2 For example, the two are opposite to each other, forming a structure similar to a through hole for passing the steel wire rope. When in use, the elastic element is placed on the bottom plate, and the elastic element and the base are placed together under the steel wire rope to be detected (for example, the main cable, the support rope, etc.), so that the steel wire rope is stuck in the lower groove on the top of the two pressure plates, and the upper cover plate is placed on the elastic element and the steel wire rope, and the upper cover plate and the bottom plate are fastened together by bolts 7, and the elastic element and the steel wire rope are clamped between the upper cover plate and the bottom plate. The bolt fastening method between the upper cover plate and the base plate can be based on the existing technology. For example, two bolts are threadedly connected to the base plate and tightened to fix them. The bolts extend upward from the base plate. The two bolts are located in the middle position in the horizontal direction and at the front and rear sides in the longitudinal direction. The extension direction of the wire rope is horizontal, passing through the spacing between the two bolts. Two light holes corresponding to the two bolts are provided on the upper cover plate. When placing the upper cover plate, the two bolts are respectively passed through the corresponding light holes on the upper cover plate, and then a nut (which can be called a tightening nut) is screwed on from the top of the bolt (above the upper cover plate), and the nut is tightened. The upper cover plate, the wire rope, the elastic element and the base are pressed together by the nut. In this state, since the lateral dimension of the upper cover is smaller than the spacing between the two pressure plates, the steel wire rope between the two pressure plates bends downward under the compression of the upper cover. At the same time, since the steel wire rope is taut and has a tendency to straighten laterally, the tension in the steel wire rope produces a certain vertical component (the component perpendicular to the base and the upper cover), which causes the pressure plate to be subjected to a certain pressure. The greater the tension of the steel wire rope (that is, the tighter it is), the greater the pressure of the steel wire rope on the pressure plate, and then the greater the pressure of the pressure plate on the elastic element, the greater the deformation of the elastic element, the greater the deformation of the resistance strain gauge along with the elastic element, and the greater the change in resistance value. Therefore, the resistance change of the resistance strain gauge is positively correlated with the tension of the steel wire rope, and the corresponding relationship between the resistance change and the tension of the steel wire rope can be established based on experiments.

[0028] If necessary, a limit nut 8 can be set on the bolt to limit the distance between the upper cover and the base when the fastening nut is tightened, so as to facilitate standardized / regular operation and avoid or reduce detection errors caused by different operations.

[0029] A detection circuit can be set on the elastic element to convert the resistance or resistance change of the resistance strain gauge into a voltage output, and then convert the voltage output into a tension display. The detection circuit can be a Wheatstone bridge circuit or other detection circuit that can detect resistance changes. The resistance strain gauge is connected to the detection circuit as a resistance element, and the voltage (or voltage change) output of the detection circuit is connected to a digital display instrument. The digital display instrument converts the connected voltage value (or voltage change value) into a corresponding force value display, thereby completing the detection of tension.

[0030] The detection circuit can be made into an electronic device, or a corresponding detection circuit product or detector available on the market can be directly used and installed at one end of the elastic element. Alternatively, an interface (e.g., a socket) 6 for connecting a resistance strain gauge is provided at one end of the elastic element so as to connect with an external detection circuit and a display instrument. In this case, the external detection circuit can be integrated into the circuit of the display instrument.

[0031] A grounding wire 9 may be provided, with its two ends respectively connected to the upper end plate and the base. Since the base is directly placed on the ground, the upper cover plate may be grounded through the grounding wire and the base.

[0032] If necessary, multiple downward extending drill rods can be set on the bottom of the base, and the ends of the drill rods are cone-shaped. After the base is placed on the ground, the base is moderately hit downward with a hammer to make the drill rods completely inserted into the ground, which not only helps the long-term stability of the tension sensor on the ground, but also helps to ensure the effectiveness and reliability of grounding.

[0033] Usually, the base, the upper cover plate and the bolts are made of metal materials, and the elastic element is made of a suitable elastic material, which can be metal or non-metal.

[0034] During on-site use, according to the actual situation, several transverse (which can be set to X direction) support ropes (transverse support ropes) and several longitudinal (which can be set to X direction) support ropes (longitudinal main cables) can be selected, and multiple tension sensors can be set for each selected support rope according to a certain spacing. The X-coordinate (corresponding to the transverse position) and Y-coordinate (corresponding to the longitudinal position) of each transverse tension sensor (tension sensor for detecting the tension of the transverse support rope) and each longitudinal tension sensor (tension sensor for detecting the tension of the longitudinal support rope) are marked to obtain the tension of the support rope at several coordinate points to form the tension distribution information of the entire protection net. According to the actual situation, several detection points (which can be called tension observation points) can also be selected to set tension sensors, and the condition and risk of the protection net can be judged according to the tension (change) condition of each detection point. According to the needs of tension information collection and monitoring, an instrument cabinet and a main control console can be set up, and several junction boxes can be set up. The detection circuit can be directly set on the tension sensor, and its output cable is connected to the junction box, and the corresponding digital display instrument is connected through the junction box. The digital display instrument converts the connected voltage into a tension value display, and connects it to the host in the main control console in the form of an electrical signal (for example, a voltage in a suitable range). The host obtains the tension detected by each tension sensor, analyzes the stress condition of the entire protection net, and then determines whether there is a risk and its cause. The specific setting method and the tension analysis and risk assessment method can be based on the existing technology.

[0035] The basic process of on-site construction is:

[0036] Select the tension observation point. The tension observation point should be the rock protrusion on the collapse body where collapse may occur, and the observation point should have a certain space to install the tension sensor;

[0037] Tension sensors are installed. Tension gauges in two directions are installed at each monitoring point to monitor the tension of the main cables of the protection net in the horizontal and vertical directions respectively, so as to conduct systematic and comprehensive automatic monitoring of the stress condition of the active protection net.

[0038] The tension distribution of the protective net can be monitored in real time through automated data collectors.

[0039] Install the instrument junction box. The instrument junction box should be installed in a safe, convenient and reliable location;

[0040] Lay special cables. Lay signal cables and control cables from the instrument cabinet and main control console to the junction box, and set up signal cables from the sensor (detection circuit) to the junction box. When laying cables, a certain margin should be left, the joints should be checked and confirmed, and the shielding layer should be firmly and reliably grounded. After the inspection and confirmation is completed, the inlet hole of the junction box should be tightly sealed.

[0041] Signal cables and control cables should be shielded in layers to prevent interference.

[0042] The cables should be checked before wiring, and the terminal heads should be crimped with special tools and number plates should be attached.

[0043] Arrange the handover materials and various installation records, hand them over to the commissioning personnel and cooperate with the commissioning

[0044] Unless otherwise specified or when one preferred or optional technical means is a further limitation of another technical means, the preferred and optional technical means disclosed in the present utility model can be arbitrarily combined to form several different specific implementation methods.

Claims

1. Tension sensor, characterized in that include: A base having a top surface; The elastic element is arranged on the top surface of the base, and a resistance strain gauge is pasted on one or both longitudinal sides of the elastic element. The left and right ends of the top surface of the elastic element are provided with pressure plates extending upward, and the top of the pressure plate is provided with a lower groove that runs through the pressure plate horizontally; The upper cover plate is located above the elastic element, and its lateral dimension is smaller than the lateral spacing between the two pressure-bearing plates, and / or a convex structure is provided in the lateral middle of its bottom surface, and the lateral dimension of the convex structure is smaller than the lateral spacing between the two pressure-bearing plates; The bolt is used to realize the threaded connection between the upper cover plate and the base, and the two ends of the bolt are respectively connected to the upper cover plate and the base, wherein at least the connection mode between the upper cover plate or the base is a threaded connection.

2. The tension sensor according to claim 1, characterized in that The main body of the elastic element is in the shape of a rectangular parallelepiped, and the pressure-bearing plate is integrated with the main body of the elastic element, or the bottom surface of the pressure-bearing plate is fixedly connected to the top surface of the main body of the elastic element.

3. The tension sensor according to claim 1, characterized in that The bottom surface of the upper cover plate is provided with or without an upper groove structure. There is one upper groove structure that runs through the bottom surface of the upper cover plate; or there are two upper groove structures that are respectively located at the two ends of the bottom surface of the upper cover plate, extending downward from the bottom surface of the upper cover plate, and an upper groove is provided at the bottom.

4. The tension sensor according to claim 1, characterized in that There are two bolts, which are located in the middle in the horizontal direction and at the front and rear sides in the vertical direction.

5. The tension sensor according to claim 4, characterized in that The lower end of the bolt is fixedly connected to the base, the top is provided with an external thread, the upper cover is provided with light holes corresponding to each bolt, the top of the bolt passes through the corresponding light hole on the upper cover, and a fastening nut is screwed on.

6. The tension sensor according to claim 4, characterized in that The bolt is provided with an upper limit nut and may or may not be provided with a lower limit nut. The upper limit nut is located below the upper cover plate to form a limit structure of the upper cover plate, and the lower limit nut is located above the base to form a limit structure of the base.

7. The tension sensor according to claim 1, characterized in that The resistance strain gauge is in sheet form and bonded to the corresponding surface of the elastic element.

8. The tension sensor according to any one of claims 1 to 7, characterized in that A detection circuit is provided, and a resistance strain gauge is connected to the detection circuit and serves as a resistive sensing element of the detection circuit.

9. The tension sensor according to claim 8, characterized in that The detection circuit adopts Huygens bridge, and the resistance strain gauge constitutes one arm of the Huygens bridge.

10. The tension sensor according to claim 9, characterized in that The Huygens bridge is arranged at one lateral end of the elastic element and is provided with a wiring terminal for outputting a detection voltage.

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