Measuring tool and cable tension measurement system

Abstract

To enable measurement of cable tension without limitation to cables that are long and used to have high tension introduced.SOLUTION: A measuring tool 10, which is used for measuring tension of a cable W that is attached to and used on a structure 1, comprises: a terminal fitting 12 fixed to an end portion of the cable W; a sensor 22 that is disposed inside a hole 20 provided in the terminal fitting 12 and fixed by a resin material filling the inside of the hole 20; and a communication unit 30 connected to a wire 24 connected to the sensor 22 and configured to transmit externally a signal representing strain detected by the sensor 22. The sensor 22 is arranged to detect strain of the terminal fitting 12 in a tensile direction of the cable W.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a measuring tool and a cable tension measurement system.

Background Art

[0002] Conventionally, as disclosed in Patent Document 1 below, a system for measuring the tension of a cable under tension is known. In the measurement system disclosed in Patent Document 1, a sensor attached to an intermediate portion of a cable to detect the acceleration of the cable, and a computer connected to the sensor and configured to calculate the tension of the cable using the detection signal of the sensor are provided. This computer calculates a power spectrum from the vibration waveform obtained when the cable is vibrated by striking the cable, reads the frequency and its mode corresponding to each peak of this power spectrum to calculate a damping coefficient, and calculates the tension corresponding to each mode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the measurement system disclosed in Patent Document 1, the cable is actually vibrated by applying an impact to the cable, and the acceleration waveform at that time is calculated to obtain the tension of the cable. In the method of obtaining the tension of the cable by such a vibration method, it is necessary that the cable is tensioned with a tension such that an accurate power spectrum can be obtained. For this reason, there is a problem that the applicable cables are limited because measurement accuracy cannot be obtained unless the cable is a long cable and is used with a high tension introduced.

[0005] Therefore, the present invention has been made in view of the above prior art, and an object thereof is to provide a measuring tool and a measuring system for determining the tension of a cable, not limited to a cable that is used with a long length and a high tension introduced thereto.

Means for Solving the Problems

[0006] In order to achieve the above object, a measuring tool according to the present invention is a measuring tool used for measuring the tension of a cable that is attached to and used on a structure, and includes a terminal fitting fixed to an end of the cable, and a sensor disposed in a hole provided in the terminal fitting and fixed by a resin material that fills the hole and adheres to the terminal fitting, a transmitter connected to the sensor and connected to a wire drawn out from the hole for transmitting a signal representing the strain detected by the sensor to the outside, and a power supply body for supplying power to the transmitter. The sensor is arranged to detect the strain of the terminal fitting in the tensile direction of the cable.

[0007] In the measuring tool according to the present invention, the sensor detects the strain of the terminal fitting in the tensile direction of the cable. By using this detected strain, it is possible to obtain the axial force generated in the terminal fitting. Since the terminal fitting is fixed to the end of the cable, the axial force generated in the terminal fitting coincides with the tension of the cable. Therefore, it is possible to obtain the tension of the cable by using the strain detected by the measuring tool. Note that since the resin material that fills the hole where the sensor is disposed is adhered to the terminal fitting, when a minute deformation occurs in the terminal fitting due to the tension of the cable, a minute deformation of the same strain as that of the terminal fitting also occurs in the resin material. Therefore, even if the sensor is not directly adhered to the terminal fitting, the strain of the terminal fitting can be detected.

[0008] Moreover, since it becomes possible to obtain the tension of the cable without using the vibration waveform of the cable, it is possible to obtain the tension of the cable even if it is not a long cable or even if the cable is not tensioned with a tension that can obtain an accurate power spectrum. Therefore, the range of cables to which it can be applied is wider than when obtaining the tension of the cable using the vibration method. Furthermore, since the sensor is disposed in the hole provided in the terminal fitting and the inside of this hole is filled with a resin material, it is possible to prevent the sensor from getting wet with water or being damaged. Also, since there is no need to provide a scratch for detecting the strain of the terminal fitting on the terminal fitting, the corrosion resistance and damage resistance of the terminal fitting can be ensured.

[0009] The terminal fitting may include a sleeve portion that houses an end portion of the cable, a shaft portion that extends from the sleeve portion, and a male screw portion that extends from a tip end of the shaft portion. In this case, a nut for locking the terminal fitting to the structure through which the male screw portion is inserted may be screwed onto the male screw portion. Also, the hole may be formed across the shaft portion from a tip end surface of the male screw portion that is exposed outside the structure. Also, the sensor may be disposed in the hole within the shaft portion. In this case, the transmitter and the power supply body may be disposed at the tip end of the male screw portion.

[0010] In this aspect, by screwing a nut onto the male screw portion of the terminal fitting, the terminal fitting can be locked to the structure. At this time, since the tip end surface of the male screw portion is at a position exposed outside the structure, the removal operation of the sensor can be performed without unloading the cable when it is necessary to remove the sensor. Therefore, it is possible to prevent the removal operation of the sensor from becoming complicated. Also, when replacing the power supply body, it is possible to replace the power supply body while the terminal fitting is locked to the structure. Therefore, since it is possible to replace the power supply body without unloading the cable, it is also possible to prevent the replacement operation of the power supply body from becoming complicated. Also, the sensor is disposed within the shaft portion and the dimensions of the shaft portion are easily known, so the calculation for obtaining the axial force of the terminal fitting does not become complicated.

[0011] The transmitter and the power supply body may be covered by a cap fixed to the male screw portion. In this aspect, it is possible to prevent the transmitter and the power supply body from getting wet or damaged by water.

[0012] The terminal fitting may include a sleeve portion that houses an end portion of the cable, a shaft portion that extends from the sleeve portion, and a bifurcated fork portion that extends from a tip end of the shaft portion. In this case, the hole may be formed across the shaft portion from a surface inside the bifurcated portion of the fork portion. Further, the sensor may be disposed in the hole within the shaft portion. In this case, the transmitter and the power supply body may be fixed to an outer side surface of the fork portion.

[0013] In this aspect, since the battery is fixed to the outer side surface of the fork portion, when replacing the power supply body, it is possible to replace the power supply body while the terminal fitting is locked to the structure. Therefore, since it is possible to replace the power supply body without unloading the cable, it is possible to prevent the replacement work of the power supply body from becoming complicated. Further, the sensor is disposed within the shaft portion, and since the dimensions of the shaft portion are easily known, the calculation for obtaining the axial force of the terminal fitting does not become complicated.

[0014] The transmitter and the power supply body may be covered by a cap fixed to the side surface of the fork portion. In this aspect, it is possible to prevent the transmitter and the power supply body from getting wet or damaged by water.

[0015] The cable tension measurement system according to the present invention includes the measuring tool and an axial force derivation unit that receives a signal transmitted from the transmitter of the measuring tool and derives an axial force of the terminal fitting from the strain.

[0016] In the cable tension measurement system according to the present invention, an axial force of the terminal fitting is derived using a signal indicating the strain output from the measuring tool. Since this axial force is the same value as the tension of the cable, the tension of the cable can be obtained.

[0017] The cable tension measurement system according to the present invention is a measuring tool used to measure the tension of a cable attached to and used in a structure, and includes a terminal fitting fixed to an end of the cable, and a sensor disposed in a hole provided in the terminal fitting, wherein the sensor is fixed by a resin material that fills the hole and adheres to the terminal fitting, a transmitter that is connected to the sensor and connected to a wire drawn out from the hole, and transmits a signal representing the strain detected by the sensor to the outside, and a power supply body that supplies power to the transmitter. The system further includes an axial force derivation unit that receives a signal transmitted from the transmitter of the measuring tool and derives an axial force of the terminal fitting from the strain. The axial force derivation unit derives the axial force of the terminal fitting using a value obtained by multiplying the strain represented by the signal from the transmitter by a calibration coefficient.

[0018] In the cable tension measurement system according to the present invention, an axial force of a terminal fitting is derived using a signal indicating a strain output from a measuring tool. That is, a value obtained by multiplying the strain represented by the signal representing the strain by the sensor by a calibration coefficient is used as the strain value of the terminal fitting, and the axial force of the terminal fitting is derived from this strain value. Since the axial force generated in the terminal fitting coincides with the tension of the cable, the tension of the cable can be obtained using the strain detected by the measuring tool.

Effects of the Invention

[0019] As described above, according to the present invention, it is possible to provide a measurement system capable of obtaining the tension of a cable, not limited to a cable used by introducing a long length and high tension, and also possible to provide a measuring tool for use in this measurement system.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0021] Hereinafter, modes for carrying out the present invention will be described in detail with reference to the drawings.

[0022] (First Embodiment) As shown in FIG. 1, the measuring tool 10 according to the present embodiment is a measuring tool 10 provided with a screw-end type terminal fitting 12. The terminal fitting 12 is fixed to one end of the cable W, and the cable W is attached to and used in the structure 1. The structure 1 may be a building such as a building, a membrane structure, a cable-stayed beam structure, a bridge (cable-stayed bridge, suspension bridge, etc.), but is not limited thereto, and may be a monument or the like. The cable W may be used to support the structure 1 itself, or may be used to support a component (beam, membrane body, etc.) of the structure 1 or to apply tension to a component. Examples of the cable W include PC steel wires, PC steel stranded wires, multi-cables, structural wire ropes, and structural stainless steel wire ropes.

[0023] The structure 1 is provided with a fixing portion 3 for fixing the terminal of the cable W, and a through hole 3a for inserting a male screw portion 16 (described later) of the terminal fitting 12 is formed in the fixing portion 3.

[0024] The terminal fitting 12 is composed of a metal object integrally having a sleeve portion 14, a shaft portion 15, and a male screw portion 16.

[0025] The sleeve portion 14 is formed in a cylindrical shape that extends straight in one direction (hereinafter also referred to as the axial direction) so as to be able to accommodate the end portion of the cable W. The tip end portion of the cable W is inserted into the sleeve portion 14, and the sleeve portion 14 is fixed to this tip end portion in a non-movable manner.

[0026] The shaft portion 15 is connected to the inner side end portion of the sleeve portion 14 and closes the opening at the inner side end portion of the sleeve portion 14. The shaft portion 15 is formed, for example, in a columnar shape with a circular cross section. Note that the form in which the opening at the inner side end portion of the sleeve portion 14 is closed by the shaft portion 15 is not limited thereto, and the sleeve portion 14 itself may be configured in a shape in which the end portion is closed. Further, the shaft portion 15 shown in FIG. 1 is formed in a shape in which the outer diameter changes stepwise in the middle portion, but the present invention is not limited to this configuration, and the shaft portion 15 may be formed in a columnar shape with a constant cross section over the entire axial direction. Further, the shaft portion 15 does not necessarily have to be formed with a circular cross section, and may be formed with a rectangular cross section.

[0027] The cross-sectional area of the shaft portion 15, that is, the cross-sectional area perpendicular to the axial direction, is known or can be easily measured. As will be described later, since the sensor 22 is disposed in the shaft portion 15 and the cross-sectional area of the shaft portion 15 is used to calculate the axial force of the terminal fitting 12, at least the cross-sectional area in the direction perpendicular to the axial direction where the sensor 22 is disposed is known or can be easily measured.

[0028] The male screw portion 16 extends in one direction (axial direction) from the tip end of the shaft portion 15 (the end portion opposite to the sleeve portion 14) and constitutes a male screw. A nut 18 is screwed onto the male screw. The male screw portion 16 is disposed in a state of protruding outward from the through hole 3a in the fixing portion 3 of the structure 1, and the nut 18 is attached to the male screw portion 16 in this state. At this time, by introducing a tension (tension in the leftward direction in FIG. 1) into the cable W, the terminal fitting 12 and the terminal of the cable W can be fixed to the fixing portion 3.

[0029] The terminal fitting 12 has a bottomed hole 20 that opens to the tip surface of the male screw portion 16 and extends along the axial direction. The hole 20 is provided in a range extending from the tip surface of the male screw portion 16 to the shaft portion 15.

[0030] As also shown in FIG. 2, a sensor 22 is disposed in the hole 20. The sensor 22 is composed of a strain gauge and is disposed at a location corresponding to the inside of the shaft portion 15 within the hole 20. The sensor 22 is disposed within the shaft portion 15 because the cross-sectional area of the shaft portion 15 in a direction perpendicular to the axial direction is known or can be easily measured. If the sensor 22 can detect the strain of the terminal fitting 12 or the resin material 26 described later in the shaft portion 15, the axial force of the terminal fitting 12 can be calculated from the strain as described later.

[0031] A wire 24 (electric wire) for transmitting a detection signal from the sensor 22 is connected to the sensor 22, and this wire 24 is drawn out from the hole 20. The inside of the hole 20 is filled with a resin material 26, but the wire 24 extends outside the resin material 26.

[0032] The resin material 26 is solidified so as to adhere to the inner peripheral surface of the hole 20. For this reason, the sensor 22 is fixed within the hole 20. The cross-section perpendicular to the axial direction of the hole 20 is very small, and since the resin material 26 is adhered to the terminal fitting 12, when the terminal fitting 12 is strained in the axial direction, the same amount of strain as that of the terminal fitting 12 also occurs in the resin material 26.

[0033] The wire 24 is connected to a communication unit 30 disposed outside the resin material 26. The communication unit 30 is disposed at the tip of the male screw portion 16 so as to sandwich a pedestal 32 between it and the tip surface of the male screw portion 16. The wire 24 is inserted through the pedestal 32 through a through-hole (not shown) provided in the pedestal 32. The communication unit 30 may be fixed to the pedestal 32 using a fastening tool such as a bolt, or may be simply fixed to the pedestal 32 using a double-sided tape or the like. The pedestal 32 is fixed to the tip surface of the male screw portion 16 using a double-sided tape or the like. Note that the pedestal 32 can be omitted, and the communication unit 30 may be disposed so as to be in direct contact with the tip of the male screw portion 16.

[0034] The communication unit 30 and the pedestal 32 are covered by a cap 35. As shown in FIG. 3, the cap 35 has an annular base portion 35a formed with an internal thread on its inner peripheral surface that is screwed onto the external thread of the external thread portion 16, and a cap portion 35b fixed to the base portion 35a using a fastener 33. By fixing the cap portion 35b to the base portion 35a fixed to the external thread portion 16, the communication unit 30 disposed in the space within the cap portion 35b is covered by the cap 35.

[0035] The communication unit 30 is configured as a wireless data logger. As shown in FIGS. 4(a) and 4(b), the communication unit 30 includes a transmitter 36, a battery 37 that is a power supply for powering the transmitter 36, and a housing 38 that houses these components. The transmitter 36 is electrically connected to the wire 24 and is configured to wirelessly transmit the detection signal from the sensor 22 while temporarily storing it. The transmitter 36 repeatedly transmits the detection signal from the sensor 22 at predetermined intervals (e.g., 1 second, 1 minute, 10 minutes, 1 hour, 1 day, etc.).

[0036] The housing 38 includes a housing main body 38a having a battery housing portion 38c for housing the battery 37, and a lid 38b for opening and closing the battery housing portion 38c, and houses the battery 37 in a replaceable manner. When the cap portion 35b of the cap 35 is removed from the base portion 35a and the battery housing portion 38c is opened by the lid 38b, the battery 37 is exposed, and thus the battery 37 can be replaced in this state. Since this replacement work is performed at the tip of the external thread portion 16 located outside the fixing portion 3 of the structure 1, it is not necessary to unload the cable W when performing the replacement work. In the present embodiment, the battery 37 is provided as an example of the power supply, but alternatively, a battery cell using renewable energy such as sunlight may be provided as the power supply. In that case, the solar cell is not covered by the cap 35 but is arranged to be exposed to the outside.

[0037] The signal emitted from the transmitter 36 is input to the controller 42 shown in FIG. 5. The controller 42 is composed of a microcomputer including a CPU that executes arithmetic processing, a ROM that stores processing programs, data, etc., and a RAM that temporarily stores data. By executing a processing program, the controller 42 functions as an axial force derivation unit 42a, a storage control unit 42b, and a display control unit 42c.

[0038] The axial force derivation unit 42a derives the axial force of the terminal fitting 12 (that is, the tension of the cable W) using the signal sent from the measuring tool 10. That is, since the signal is repeatedly sent from the transmitter 36 at predetermined intervals, the axial force derivation unit 42a derives the axial force of the terminal fitting 12 (that is, the tension of the cable W) every time it receives the signal.

[0039] The axial force derivation unit 42a uses the strain of the terminal fitting 12 indicated by the signal and the Young's modulus (longitudinal elastic modulus) of the metal constituting the terminal fitting 12 to derive the stress in the axial portion 15 of the terminal fitting 12. The Young's modulus is stored in the controller 42. The derived stress is the stress in the axial direction.

[0040] Further, the axial force derivation unit 42a uses the derived stress and the cross-sectional area perpendicular to the axial direction at the portion where the sensor 22 is disposed in the axial portion 15 (stored in the controller 42) to derive the axial force in the axial portion 15 of the terminal fitting 12. The value of the axial force generated in the axial portion 15 is the same as the value of the axial force generated in the sleeve portion 14, and this axial force acts as the tension generated at the end of the cable W fixed within the sleeve portion 14. Therefore, by deriving the axial force of the terminal fitting 12, the cable W tension generated at the end of the cable W is obtained.

[0041] The storage control unit 42b performs processing for storing the value of the axial force (that is, the tension of the cable W) derived by the axial force derivation unit 42a in the storage unit in association with the reception time from the sensor 22. The display control unit 42c performs processing for displaying the values of a series of axial forces (that is, the tension of the cable W) stored in the storage unit on the display unit over time.

[0042] As shown in FIG. 5, a cable tension measurement system 45 for measuring the tension of the cable W is configured by a measuring tool 10 and a controller 42 that also functions as an axial force derivation unit 42a.

[0043] Note that the timing for introducing tension into the cable W is after the terminal fitting 12 having the sensor 22 is fixed to the fixing portion 3 of the structure 1. Therefore, when tension is introduced into the cable W, the sensor 22 composed of a strain gauge deforms accordingly, so that the tension applied by the controller 42 can be derived. Therefore, if tension is introduced into the cable W while calculating the tension, it is possible to apply a tension within an appropriate range to the cable W.

[0044] As described above, in the measuring tool 10 according to the present embodiment, the sensor 22 detects the strain of the terminal fitting 12 in the tensile direction of the cable W. By using this detected strain, it is possible to obtain the axial force generated in the terminal fitting 12. Since the terminal fitting 12 is fixed to the end of the cable W, the axial force generated in the terminal fitting 12 coincides with the tension of the cable W. For this reason, it becomes possible to obtain the tension of the cable W by using the strain detected by the measuring tool 10. Since the resin material 26 is adhered to the terminal fitting 12, when a minute deformation occurs in the terminal fitting 12 due to the tension of the cable W, a minute deformation of the same strain as that of the terminal fitting 12 also occurs in the resin material 26. Therefore, even if the sensor 22 is not directly adhered to the terminal fitting 12, the strain of the terminal fitting 12 can be detected.

[0045] Moreover, since it becomes possible to obtain the tension without using the vibration waveform of the cable W, it is possible to obtain the tension of the cable W even if it is not a long cable W or even if the cable W is not tensioned with a tension that can obtain an accurate power spectrum. Therefore, the applicable range of the cable W is widened compared to the case where the tension of the cable W is obtained using the vibration method. Further, since the sensor 22 is disposed in the hole 20 provided in the terminal fitting 12 and the inside of the hole 20 is filled with the resin material 26, it is possible to prevent the sensor 22 from being wetted by water or damaged. In addition, since it is not necessary to provide a scratch for detecting the strain of the terminal fitting 12 on the terminal fitting 12, the corrosion resistance and damage resistance of the terminal fitting 12 can be ensured.

[0046] Also, in the present embodiment, the terminal fitting 12 can be locked to the structure 1 by screwing the nut 18 onto the male screw portion 16 of the terminal fitting 12. At this time, since the tip surface of the male screw portion 16 is located at a position exposed to the outside of the structure 1, the removal operation of the sensor 22 can be performed without unloading the cable W when it is necessary to remove the sensor 22. Therefore, it is possible to prevent the removal operation of the sensor 22 from becoming complicated. Also, when replacing the battery 37, it is possible to replace the battery 37 while the terminal fitting 12 is locked to the structure 1. Therefore, since it is possible to replace the battery 37 without unloading the cable W, it is also possible to prevent the replacement operation of the battery 37 from becoming complicated. Further, since the sensor 22 is disposed inside the shaft portion 15 and the dimensions of the shaft portion 15 can be easily understood, the calculation for obtaining the axial force of the terminal fitting 12 does not become complicated.

[0047] Also, in the present embodiment, since the communication unit 30 having the transmitter 36 and the battery 37 is covered by the cap 35, it is possible to prevent the transmitter 36 and the battery 37 from being wetted by water or damaged.

[0048] Also, in the cable tension measurement system 45 according to the present embodiment, the axial force of the terminal fitting 12 is derived in the controller 42 using a signal indicating the strain output from the measuring tool 10. Since this axial force has the same value as the tension of the cable W, the tension of the cable W can be obtained.

[0049] (Second Embodiment) Figs. 6(a) and 6(b) show the measuring tool 10 according to the second embodiment. Here, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0050] The measuring tool 10 according to the second embodiment is a measuring tool 10 provided with a fork-end type terminal fitting 12. The terminal fitting 12 is composed of a metal object integrally having a sleeve portion 14, a shaft portion 15, and a bifurcated fork portion 48. The sleeve portion 14 and the shaft portion 15 have the same configuration as the sleeve portion 14 and the shaft portion 15 in the terminal fitting 12 of the first embodiment.

[0051] The fork portion 48 is provided at the tip of the shaft portion 15 (the end opposite to the sleeve portion 14), and integrally has a block portion 48a connected to the shaft portion 15, and a pair of leg portions 48b and 48c extending in one direction (axial direction) at intervals from the block portion 48a. Mounting holes 48d are respectively provided in the pair of leg portions 48b and 48c so as to penetrate therethrough. By locking a pin (not shown) inserted through the mounting hole 48d to a fixing portion (having a pin insertion hole) provided in the structure 1, the terminal fitting 12 can be fixed to the fixing portion.

[0052] In the terminal fitting 12, a bottomed hole 20 that opens to the front end surface of the block portion 48a in the fork portion 48 and extends along the axial direction is formed. The hole 20 is provided in a range extending from the front end surface of the block portion 48a to the shaft portion 15. That is, the hole 20 is formed from the inner surface of the bifurcated portion of the fork portion 48 to the shaft portion 15. The inside of the hole 20 is filled with a resin material 26.

[0053] The sensor 22 is disposed at a location corresponding to the inside of the shaft portion 15 within the hole 20. The reason why the sensor 22 is disposed within the shaft portion 15 is that the cross-sectional area of the shaft portion 15 in the direction perpendicular to the axial direction is known or can be easily measured.

[0054] The wire 24 connected to the sensor 22 is drawn out from the resin material 26 filling the hole 20 to the outside (outside the front end surface of the block portion 48a), and is drawn out to the outer side surface 48e of the leg portion 48b through the lead-out hole 49 formed to penetrate one leg portion 48b in the fork portion 48. The wire 24 is inserted through the pedestal 32 through a through hole (not shown) provided in the pedestal 32.

[0055] The communication unit 30 is disposed on the outer side surface 48e of the leg portion 48b so as to sandwich the pedestal 32 between it and the outer side surface 48e of the leg portion 48b. The communication unit 30 may be fixed to the pedestal 32 using a fastening tool such as a bolt, or may be simply fixed to the pedestal 32 with a double-sided tape or the like. Also, the pedestal 32 is fixed to the outer side surface 48e of the leg portion 48b with a double-sided tape or the like. Note that the pedestal 32 can be omitted, and the communication unit 30 may be disposed so as to be in direct contact with the outer side surface 48e of the leg portion 48b.

[0056] The signal sent from the communication unit 30 is received by a controller 42 having the same configuration as the controller 42 shown in FIG. 5. A cable tension measurement system 45 for measuring the tension of the cable W is constituted by the measuring tool 10 and the controller 42 which also functions as an axial force derivation unit 42a.

[0057] The cap 35 has an annular base portion 35a fixed to the side surface 48e of the leg portion 48b using the fastener 33, and a cap portion 35b integrally formed with the base portion 35a so as to form a space between the base portion 35a and the leg portion 48b. The communication unit 30 is housed in the cap 35 fixed to the outer side surface 48e of the leg portion 48b. Therefore, as shown in FIG. 7, the communication unit 30 is arranged on the side surface 48e side of the leg portion 48b with the pedestal 32 interposed therebetween, and the cap 35 is fixed to the leg portion 48b so as to cover the pedestal 32 and the communication unit 30, so that the communication unit 30 is not exposed. Further, although the wire 24 connected to the sensor 22 is exposed inside the leg portion 48b (see FIG. 6(a)), it is not exposed on the outer surface side of the leg portion 48b.

[0058] Therefore, in the present embodiment, since the communication unit 30 that houses the battery 37 is fixed to the outer side surface 48e of the fork portion 48, when replacing the battery 37, the battery 37 can be replaced while the terminal fitting 12 is locked to the structure 1. Therefore, since the battery 37 can be replaced without unloading the cable W, it is possible to prevent the battery 37 replacement work from becoming complicated. Further, since the sensor 22 is arranged inside the shaft portion 15 and the dimensions of the shaft portion 15 are easily known, the calculation for obtaining the axial force of the terminal fitting 12 does not become complicated.

[0059] Further, in the present embodiment, since the communication unit 30 having the transmitter 36 and the battery 37 is covered by the cap 35 fixed to the side surface 48e of the fork portion 48, it is possible to prevent the transmitter 36 and the battery 37 from getting wet with water or being damaged.

[0060] Note that although the description of other configurations, operations, and effects is omitted, the description of the first embodiment can be incorporated into the second embodiment.

[0061] (Other Embodiments) Note that the embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The present invention is not limited to the above-described embodiments, and various changes, improvements, etc. are possible without departing from the spirit thereof. For example, in the measuring tool 10 of the above-described embodiment, although the communication unit 30 is covered with the cap 35, if the housing 38 of the communication unit 30 itself has a waterproof function, the cap 35 can be omitted. Also, when the measuring tool 10 is installed in a place where it will not be exposed to rain, the cap 35 can be omitted.

[0062] In the above-described embodiment, on the premise that the resin material 26 generates the same amount of strain as the terminal fitting 12, the detection signal by the sensor 22 is used for deriving the axial force of the terminal fitting 12. However, it is not limited to this, and a value obtained by multiplying the strain value detected by the sensor 22 by a calibration coefficient may be used as the strain value of the terminal fitting 12 to derive the axial force of the terminal fitting 12. That is, since the strain value of the resin material 26 and the strain value of the terminal fitting 12 may not match, in such a case, the relationship between the strain value of the resin material 26 and the strain value of the terminal fitting 12 in a state where tension is applied to the cable W may be acquired in advance, and the strain value of the terminal fitting 12 may be obtained using the calibration coefficient indicating the relationship. By doing so, even when the strain value of the resin material 26 does not become the same value as the strain value of the terminal fitting 12, the axial force of the terminal fitting 12 can be derived.

[0063] In the above-described embodiment, the hole 20 formed in the terminal fitting 12 has a bottom, but it is not limited to the bottomed hole 20. The hole 20 may extend, for example, to the inside of the sleeve portion 14 and be connected to the space inside the sleeve portion 14 (the space in which the tip of the cable W is accommodated).

Explanation of Reference Numerals

[0064] 1 : Structure 10 : Measuring tool 12 : Terminal fitting 14 : Sleeve portion 15 : Shaft portion 16 : Male screw portion 18: Nut 20: Hole 22: Sensor 24: Wire 26: Resin material 30: Communication unit 35: Cap 36: Transmitter 37: Battery 42: Controller 42a: Axial force derivation part 45: Cable tension measurement system 48: Fork part 48a: Block part 48b: Leg part 48e: Side surface W: Cable

Claims

1. A measuring tool used to measure the tension of a cable attached to and used on a structure, a terminal fitting fixed to an end of the cable, a sensor disposed in a hole provided in the terminal fitting, the sensor being fixed by a resin material that fills the hole and adheres to the terminal fitting, a transmitter connected to the sensor and also connected to a wire drawn out from the hole, the transmitter transmitting a signal representing the strain detected by the sensor to the outside, a power supply body for supplying power to the transmitter, comprising: The sensor is arranged to detect the strain of the terminal fitting in the tensile direction of the cable. A measuring tool.

2. The terminal fitting has a sleeve portion that houses an end of the cable, a shaft portion extending from the sleeve portion, and a male screw portion extending from a tip of the shaft portion, a nut for locking the terminal fitting to the structure through which the male screw portion is inserted is screwed onto the male screw portion, the hole is formed from a tip surface of the male screw portion exposed outside the structure across the shaft portion, the sensor is disposed in the hole within the shaft portion, The transmitter and the power supply body are disposed at a tip of the male screw portion. The measuring tool according to claim 1.

3. The transmitter and the power supply body are covered by a cap fixed to the male screw portion. The measuring tool according to claim 2.

4. The terminal fitting has a sleeve portion that houses an end of the cable, a shaft portion extending from the sleeve portion, and a bifurcated fork portion extending from a tip of the shaft portion, the hole is formed from a surface inside the bifurcations of the fork portion across the shaft portion, the sensor is disposed in the hole within the shaft portion, The transmitter and the power supply body are fixed to a side surface outside the fork portion. The measuring tool according to claim 1.

5. The transmitter and the power supply body are covered by a cap fixed to the side surface of the fork portion. The measuring tool according to claim 4.

6. The measuring tool according to any one of claims 1 to 5, and an axial force derivation unit that receives a signal transmitted from the transmitter of the measuring tool and derives an axial force of the terminal fitting from the strain. A cable tension measurement system comprising.

7. A measuring tool used to measure the tension of a cable attached to and used on a structure, A terminal fitting fixed to an end of the cable, A sensor disposed in a hole provided in the terminal fitting, the sensor being fixed by a resin material that fills the hole and adheres to the terminal fitting, A transmitter that is connected to the sensor and also connected to a wire drawn out from the hole, and transmits an external signal representing the strain detected by the sensor, A power supply body that supplies power to the transmitter, A measuring instrument having, A shaft force derivation unit that receives a signal transmitted from the transmitter of the measuring tool and derives the axial force of the terminal fitting from the strain, Comprising, The axial force derivation unit derives the axial force of the terminal fitting using a value obtained by multiplying the strain represented by the signal from the transmitter by a calibration coefficient, a cable tension measurement system.

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