Cable force sensor

Abstract

The utility model relates to the field of tension sensors, and particularly discloses a cable force sensor. According to the utility model, through the arrangement of the cable hoop, the wire shaft, the stay wire type displacement sensor and the displacement sensor stay wire, a user can install the cable hoop on the tested steel cable, when the cable force of the tested steel cable changes, the length of the steel cable changes, and the steel cable with the changed length drives the cable hoop to move, so that the cable hoop can move. The moving cable hoop drives the displacement sensor stay wire to move, the stay wire type displacement sensor records the moving distance of the displacement sensor stay wire, the moving distance of the cable hoop is calculated through the moving distance of the displacement sensor stay wire, the moving distance of the measured steel cable is reflected, then the cable force change of the steel cable is measured, and the prestress of the steel cable is combined. And the total cable force value of the measured steel cable can be calculated.

Description

Technical Field

[0001] This utility model belongs to the field of tension sensor technology, specifically relating to a cable force sensor. Background Technology

[0002] With the development of modern construction industry, a green and low-carbon building component—prestressed steel cable component—has emerged. Due to its high strength, small size, light weight, and good corrosion resistance, it is widely used in large bridges, airport waiting halls, terminal buildings, high-speed rail stations, and large commercial buildings. Because of these characteristics, prestressed steel cables generally play an extremely important role in the aforementioned building structures. For example, in prestressed cable-stayed bridges where prestressed steel cables connect the towers and the bridge deck, the prestressed steel cables bear almost 60% to 80% of the bridge's dead load and the loads from vehicles and pedestrians. Its importance is self-evident. Because of its crucial position in the building structure safety system, it is essential to monitor the cable forces of the prestressed steel cables in a timely and accurate manner during construction and use.

[0003] Currently, the more mature methods for measuring prestressed steel cables include the oil gauge reading method, the frequency method, the load cell method, and the magnetic flux sensor method. The oil gauge reading method uses the tensioning equipment—jacks and oil gauges—used during the prestressing cable tensioning process to read the cable force at the tensioning end. However, after the building is completed and the equipment is removed, cable force measurement becomes extremely difficult and costly. Furthermore, because this method can only measure the cable end where the tensioning equipment can be installed, and not the cable force at any other part of the cable body, its application is limited to measuring the cable force at the end during construction. The frequency method utilizes the physical relationship between cable force and frequency in prestressed steel cables to develop a cable force detection method. However, this method is only accurate for simply supported cables without other interfering components. If the cable body is connected to other building components, such as other cables, steel beams, or struts, the natural frequency of the cable being tested will be distorted by these components, making this method impractical. The load cell method involves embedding tension or pressure sensors at the end of the prestressed steel cable. The instrument, similar to the oil gauge reading method, transmits the prestressed cable force through its structure, thus measuring the prestressed cable force. However, because this method is embedded in the fixed part of the cable and participates in the cable's stress, it is limited to measuring the cable force at the embedded location, is costly, and carries the risk of sensor failure that cannot be repaired, thus its application is not widespread. The magnetic flux method utilizes the magnetostrictive effect of the object being tested—the prestressed cable. That is, changes in cable stress lead to changes in the cable's permeability, which in turn cause changes in the physical quantity of the applied magnetic field. By measuring the changing physical quantity of the magnetic field, the corresponding cable stress (cable force) is obtained using the monotonic relationship between the cable stress and the magnetic field physical quantity. However, ambient temperature affects the cable's permeability, and the cable force measurement results may differ under the same external force but at different temperatures. In particular, the magnetic flux sensor itself generates heat, causing changes in the temperature of the measuring coil, which in turn leads to different measurement results. Therefore, a new sensor with a simple structure is needed that can avoid the influence of factors such as temperature and accurately measure the cable force. Utility Model Content

[0004] In order to overcome the shortcomings of the existing technology, the purpose of this utility model is to provide a cable force sensor to solve the problems that traditional steel cable force measuring devices have limited applicability and the measurement results are affected by environmental factors, which leads to inaccurate measurement results.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] A cable force sensor, comprising:

[0007] At least two cable clamps are provided, and both cable clamps are connected to the steel cable being tested;

[0008] Multiple spools are provided and are connected at equal intervals in a circular array on the cable hoop, and grooves are provided on the spools.

[0009] A wire-type displacement sensor is connected to one of the aforementioned cable clamps;

[0010] The displacement sensor pull wire is wound in the groove of the multiple spools, with one end of the displacement sensor pull wire connected to the pull-wire displacement sensor and the other end connected to the cable hoop.

[0011] Preferably, a filling layer is provided between the cable clamp and the steel cable being tested, and the filling layer is a soft metal filler.

[0012] Preferably, the cable hoop includes a first half-ring and a second half-ring, the second half-ring having an installation hole, and a locking bolt being provided inside the installation hole. The first half-ring and the second half-ring are spliced ​​together by the locking bolt, and the first half-ring and the second half-ring are spliced ​​together to form a ring. The spool is connected to the first half-ring and the second half-ring.

[0013] Preferably, the displacement sensor cable is tensioned between adjacent spools.

[0014] Preferably, the formula for calculating the cable force of the tested steel cable is:

[0015]

[0016] in:

[0017] F - Change in the tension of the steel cable being measured;

[0018] A - Effective cross-sectional area of ​​the steel cable being measured;

[0019] E S - The elastic modulus of the steel cable being tested;

[0020] a-Measurement values ​​of a-wire displacement sensor;

[0021] N - The number of wires wound in the displacement sensor cable;

[0022] L - The distance between the spools corresponding to the upper and lower cable clamps.

[0023] Compared with the prior art, the beneficial effects of this utility model are:

[0024] This invention utilizes a cable hoop, a spool, a pull-wire displacement sensor, and a displacement sensor pull wire. The user can install the cable hoop on the steel cable being tested. When the cable force changes, the cable length changes, causing the cable hoop to move. This moving cable hoop, in turn, moves the displacement sensor pull wire. The pull-wire displacement sensor records the distance the pull wire moves, and the distance the cable hoop moves is calculated from this distance, reflecting the movement distance of the steel cable being tested. This allows for the measurement of the cable force change. Combined with the cable's prestress, the total cable force value of the tested steel cable can be calculated.

[0025] The cable force is obtained by measuring the total elongation near the measurement point of the prestressed cable and combining it with the mechanical properties of the cable. The measurement method is relatively direct, and the result is the absolute value of the cable force or the absolute value of the cable force increment. There are no intermediate physical quantities in other measurement methods, such as the magnetic field and magnetic flux in the magnetic flux method or the measurement frequency in the frequency method. This is because the use of intermediate physical quantities means introducing more uncertainties and errors in the measurement. Therefore, the cable force measurement error can be reduced.

[0026] This sensor measuring device can minimize the influence of temperature on the measurement results, because temperature changes themselves will cause the steel cable to deform, which in turn will cause changes in cable force. This change will be measured by the wire displacement sensor. This application uses a wire displacement sensor, which measures displacement by pulse counting, and the measurement results are more stable and reliable.

[0027] The measuring device of this utility model is separated from the force-bearing system of the prestressed steel cable, that is, the measuring part does not participate in the force of the structure. Therefore, the requirements for the use of the measuring device are greatly reduced. By simplifying the structure of the measuring part, the economic benefits can be greatly improved, and the measuring range can be maximized.

[0028] This invention can achieve high measurement accuracy and resolution, and can also be adjusted according to different needs. As can be seen from the working principle, the micro deformation of the steel cable is magnified by N times and then read by the wire displacement sensor. The magnification factor is the number of wires wound in the wire displacement sensor. The larger N is, the higher the accuracy of the measurement result and the smaller the resolution. Thus, the measurement accuracy and resolution can be adjusted according to different needs, which is something that other sensors cannot easily achieve.

[0029] This invention has low requirements for sensor calibration. Since it obtains cable force by measuring cable strain, and the strain-stress of prestressed cable is almost linear during the working stage, the curve equation can be determined with just one calibration point. This is different from other measurement methods that have intermediate physical quantities. It can obtain the stress change of the measured cable more directly through the strain of the prestressed cable.

[0030] This utility model can be used for measuring the cable force of existing prestressed steel cables. As can be seen from the structure and installation method of the sensor, the sensor is fixed to the steel cable being measured by two semi-circular cable hoops, which means it can be used for post-measurement. It can be used for the incremental measurement of cable force that has been built and put into use, or for the full cable force measurement by superimposing the initial force value when the installation device is installed, without the need for other operations on the prestressed steel cables that are in use.

[0031] This utility model device is easy to install and dismantle, and has extremely low maintenance and replacement costs, which greatly improves the economic benefits in the later stage. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0033] Figure 2 This is a cross-sectional schematic diagram of a cable force sensor mounting structure disclosed in this utility model;

[0034] In the diagram: 1. First half-ring; 2. Second half-ring; 3. Mounting hole; 4. Locking bolt; 5. Bollard; 6. Wire groove; 7. Filler layer; 8. Displacement sensor pull wire; 9. Pull-wire displacement sensor. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0036] Example:

[0037] Please see Figure 1 - Figure 2 As shown, a cable force sensor includes:

[0038] At least two cable clamps are provided, and both cable clamps are connected to the steel cable being tested;

[0039] Multiple spools 5 are provided and are connected at equal intervals in a circular array on the cable hoop, and the spools 5 are provided with grooves 6.

[0040] A wire-type displacement sensor 9 is connected to one of the aforementioned cable clamps;

[0041] The displacement sensor pull wire 8 is wound in the groove 6 of the plurality of the spools 5, and one end of the displacement sensor pull wire 8 is connected to the pull wire displacement sensor 9, and the other end is connected to the cable hoop.

[0042] As can be seen from the above, this utility model, by setting up a cable hoop, a spool 5, a pull-wire displacement sensor 9, and a displacement sensor pull wire 8, allows the user to install the cable hoop on the steel cable being tested. When the cable force of the steel cable changes, the length of the steel cable will change. The change in length of the steel cable will cause the cable hoop to move, and the moving cable hoop will cause the displacement sensor pull wire 8 to move. The pull-wire displacement sensor 9 records the moving distance of the displacement sensor pull wire 8. The moving distance of the cable hoop is calculated by the moving distance of the displacement sensor pull wire 8, reflecting the moving distance of the steel cable being tested, and thus measuring the change in the cable force. Combined with the prestress of the steel cable, the total cable force value of the steel cable being tested can be calculated.

[0043] A filling layer 7 is provided between the cable clamp and the steel cable being tested. The filling layer 7 is a soft metal filler, which can be a soft metal alloy. It is used to fill the gap between the steel cable being tested and the cable clamp, increase the friction between the cable clamp and the steel cable being tested, so that the stretched steel cable can drive the cable clamp to move in time. Then, the cable clamp stretches the displacement sensor wire 8, and the elongation of the displacement sensor wire 8 accurately reflects the elongation of the steel cable being tested.

[0044] The cable clamp includes a first half-ring 1 and a second half-ring 2. The second half-ring 2 has a mounting hole 3, and a locking bolt 4 is installed inside the mounting hole 3. The first half-ring 1 and the second half-ring 2 are spliced ​​together by the locking bolt 4 to form a ring. The spool 5 is connected to the first half-ring 1 and the second half-ring 2. The user can clamp the first half-ring 1 and the second half-ring 2 onto the steel cable being tested, and then combine the first half-ring 1 and the second half-ring 2 together by the locking bolt 4. At this time, the first half-ring 1 and the second half-ring 2 will be clamped onto the steel cable being tested. As mentioned above, the user can adjust the locking force of the locking bolt 4 to make the half-rings firmly clamped onto the steel cable being tested. When measuring some thinner steel cables, a filling layer 7 can be set between the half-rings and the steel cable to ensure that the stretched steel cable can drive the first half-ring 1 and the second half-ring 2 to move.

[0045] In order for the wire-type displacement sensor 9 to accurately measure the displacement value of the displacement sensor wire 8, the displacement sensor wire 8 is taut between adjacent spools 5. At this time, the tension of the steel cable being measured can be accurately reflected on the displacement sensor wire 8.

[0046] When a prestressed steel cable is subjected to external force, it elongates. If the distance between the cable hoops is L (which is actually the center distance between the upper and lower grooves 6), and the number of windings of the wire displacement sensor 9 is N, and the elongation of the steel cable under test is ΔL, then the single-end displacement value measured by the wire displacement sensor 9 is NΔL. The cable force value can be obtained according to the formulas of mechanics of materials. The calculation process is as follows:

[0047]

[0048] If the displacement reading of the pull-wire displacement sensor 9 is a, and the number of wires wound is N, then

[0049] Therefore, the formula for calculating the cable force of the tested steel cable is as follows:

[0050]

[0051] in:

[0052] ε – The strain value of the steel cable;

[0053] F - Change in the tension of the steel cable being measured;

[0054] A - Effective cross-sectional area of ​​the steel cable being measured;

[0055] E S - The elastic modulus of the steel cable being tested;

[0056] The measured value of a-wire displacement sensor 9;

[0057] The number of wires wound in the N-displacement sensor pull wire 8;

[0058] L - The distance between the two spools 5 corresponding to the upper and lower cable clamps.

[0059] This invention uses the method of measuring the total elongation, i.e., the total strain, near the measurement point of the prestressed steel cable to derive the cable force based on the mechanical properties of the cable. The measurement method is the most direct, and the result is the absolute value of the cable force or the absolute value of the cable force increment. There are no intermediate physical quantities in other measurement methods, such as the magnetic field and magnetic flux in the magnetic flux method, or the frequency measurement in the frequency method, because using intermediate physical quantities means introducing more uncertainties and errors into the measurement.

[0060] This invention minimizes the impact of temperature on measurement results. Temperature changes cause deformation of the steel cable and even changes in cable force, which is precisely what the wire displacement sensor detects. Other measurement methods often suffer from significant deviations due to improper handling of temperature effects. For example, in cable force measurement using a magnetic flux sensor, temperature affects the permeability of the steel cable, meaning that measurement results under the same external force at different temperatures may differ. This is especially true because the magnetic flux sensor itself generates heat, causing temperature changes in the measuring coil, which in turn lead to different measurement results. Similarly, load cells typically use resistance strain gauges, and the measuring circuit and strain gauges themselves are susceptible to temperature variations and temperature drift, making temperature effects difficult to handle. Frequency-based measurements also present temperature issues because the temperature effects of the sensor's vibrating wire and the cable body are not identical. This solution uses an encoder-driven displacement sensor, which measures displacement by counting pulses. For example, the encoder generates a fixed number of pulses per revolution, typically 1024 to 4096. For a specific sensor, the displacement value represented by one pulse is stable. Therefore, this sensor converts the displacement measurement into a more reliable pulse count, resulting in more stable and reliable measurement results.

[0061] The measuring device of this invention is separated from the force-bearing system of the prestressed steel cable, meaning the measuring system does not participate in the stress on the structure. Therefore, the requirements for the measuring device are greatly reduced, significantly improving economic efficiency and maximizing the measurement range. Taking a load cell as an example, the measurement process involves the prestressed steel cable transmitting its force to the load cell, causing a slight deformation in the sensor's bearing device, which is detected by the sensor's measuring circuit and processed. This method places very high demands on the sensor itself. For example, the force of a large prestressed steel cable typically ranges from tens to hundreds of tons or even higher, so the sensor's bearing capacity must be matched; otherwise, it will fail due to insufficient bearing capacity. This invention, however, only measures the slight deformation of the prestress and does not participate in the stress on the prestressed steel cable.

[0062] This invention can achieve high measurement accuracy and resolution, and can also be adjusted according to different needs. As can be seen from the working principle described above, the micro-deformation of the steel cable is amplified by N times and then read by the wire displacement sensor. The amplification factor is the number of wires wound in the wire displacement sensor. The larger N is, the higher the accuracy of the measurement result and the finer the resolution. Thus, the measurement accuracy and resolution can be adjusted according to different needs, which is something that other sensors cannot easily do.

[0063] This invention has lower requirements for sensor calibration because it derives cable force by measuring cable strain. Since the strain-stress ratio of a prestressed cable during operation is almost linear, only one calibration point is needed to determine its curve equation. This differs from other measurement methods that involve intermediate physical quantities. For example, in magnetic flux sensor methods, due to differences in permeability at different measurement points on the same cable, calibration is required for each measurement point, and temperature calibration is also necessary. Similarly, different load cells require calibration based on their different principles and the characteristics of their measurement circuits.

[0064] This invention can be used to measure the cable force of existing prestressed steel cables. As can be seen from the structure and installation of the sensor described above, this invention uses two semi-circular cable hoops fixed to the steel cable being measured, which means it can be used for post-measurement. It can be used for incremental or total cable force measurement of cables that have been built and put into use. The initial force value when the installation device is superimposed is the absolute value of the total cable force. No other operations are required on the prestressed steel cable that is in use. For example, closed magnetic flux sensors require the removal or even replacement of the steel cable to install the sensor, and the same applies to weighing sensors.

[0065] This utility model device is easy to install and dismantle, and has extremely low maintenance and replacement costs, which greatly improves the economic benefits in the later stage.

[0066] All standard parts used in this invention can be purchased from the market, and irregularly shaped parts can be customized according to the description and drawings. The specific connection methods for each part all employ conventional methods such as bolts, rivets, and welding, which are mature technologies in the prior art. The machinery, parts, and equipment all use conventional models in the prior art, and the circuit connections also use conventional connection methods in the prior art, which will not be detailed here. Any content not described in detail in this specification belongs to the prior art known to those skilled in the art.

[0067] In the description of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. "A plurality of" means two or more, unless otherwise explicitly specified.

[0068] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0069] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0070] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0071] The accompanying drawings of the embodiments disclosed in this utility model only involve the structures involved in the embodiments disclosed in this utility model. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this utility model can be combined with each other.

Claims

1. A cable force sensor, characterized in that, include: At least two cable clamps are provided, and both cable clamps are connected to the steel cable being tested; Multiple spools (5) are provided, and the multiple spools (5) are connected to the cable hoop in a ring array at equal intervals, and the spools (5) are provided with grooves (6). A wire-type displacement sensor (9) is connected to one of the cable clamps; The displacement sensor pull wire (8) is wound in the groove (6) of the multiple spools (5), and one end of the displacement sensor pull wire (8) is connected to the pull wire displacement sensor (9), and the other end is connected to the cable hoop.

2. A cable force sensor according to claim 1, characterized in that: A filling layer (7) is provided between the cable hoop and the steel cable being tested. The filling layer (7) is a soft metal filler.

3. A cable force sensor according to claim 1, characterized in that: The cable hoop includes a first half-ring (1) and a second half-ring (2). The second half-ring (2) has an installation hole (3) and a locking bolt (4) is provided inside the installation hole (3). The first half-ring (1) and the second half-ring (2) are spliced ​​together by the locking bolt (4). The first half-ring (1) and the second half-ring (2) are spliced ​​together to form a ring. The spool (5) is connected to the first half-ring (1) and the second half-ring (2).

4. A cable force sensor according to claim 1, characterized in that: The displacement sensor pull wire (8) is taut between adjacent spools (5).

5. A cable force sensor according to claim 1, characterized in that: The formula for calculating the cable force of the tested steel cable is: ； in: F - Change in the tension of the steel cable being measured; A - Effective cross-sectional area of ​​the steel cable being measured; E S - The elastic modulus of the steel cable being tested; The measured value of the a-wire displacement sensor (9); The number of windings in the N-displacement sensor pull wire (8); L - The distance between the bobbins (5) corresponding to the upper and lower cable hoops.

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