JP5944930B2 - Strain measuring device - Google Patents

Description

  The present invention relates to a strain measuring device.

  For example, a strain measuring device that measures strain of an object to be measured is known (for example, Patent Document 1).

JP 2011-89936 A

  For example, in the strain measuring apparatus of Patent Document 1, the capacitance between a cylindrical electrode attached to the object to be measured and a rod electrode attached to the object to be measured so as to be inserted into the cylindrical electrode. Based on this value, the strain of the object to be measured is measured. In this strain measurement device, for example, the measurement accuracy of the capacitance may be reduced due to the influence of the stray capacitance or the like when measuring the capacitance. In this case, there is a risk that the measurement accuracy of the strain measurement apparatus for the object to be measured is lowered.

The main present invention for solving the above-described problems includes a cylindrical electrode, a first case made of metal having an inner diameter larger than the outer diameter of the cylindrical electrode and accommodating the cylindrical electrode, and the first An insulating first support member for supporting the cylindrical electrode inside the first case so that the cylindrical electrode does not contact the case; A rod-shaped electrode inserted into the cylindrical electrode, and a metal first electrode having an inner diameter larger than an outer diameter of the rod-shaped electrode and accommodating the rod-shaped electrode so that the rod-shaped electrode is inserted into the cylindrical electrode. Two cases, and an insulating second support member that supports the rod-shaped electrode inside the second case so that the rod-shaped electrode does not contact the second case, and is attached to the object to be measured. Second electrode body and the rod-shaped Based on the measurement result of the first measuring device that measures the capacitance determined according to the length of the portion of the pole inserted into the cylindrical electrode, the direction of the insertion of the rod-shaped electrode in the object to be measured A second measuring device that measures the amount of strain, wherein the first measuring device includes a first conductive line having one end connected to a voltage source, a first conductor provided around the first conductive line, A second conductive line having one end connected to the voltmeter; a second conductor provided around the second conductive line and connected to the first conductor; and a third conductive line having one end connected to the amplifier; A third conductor provided around the third conductive line; a fourth conductive line having one end connected to an ammeter; and a fourth conductor provided around the fourth conductive line and connected to the third conductor. A conductor, and one of the cylindrical electrode and the rod-shaped electrode is The other electrode of the cylindrical electrode and the rod electrode is connected to the other end of the first and second conductive lines, and the other electrode is connected to the other end of the third and fourth conductive lines. One case that accommodates the one of the two cases is connected to the first and second conductors, and the other case of the first and second cases is the third and fourth conductors. And a conductive cable connected between the first and second cases, and the first and second cases are connected to each other at both ends of the conductive cable, respectively. And a strain measuring device welded to the second case .

  Other features of the present invention will become apparent from the accompanying drawings and the description of this specification.

  ADVANTAGE OF THE INVENTION According to this invention, the measurement precision of the distortion in a to-be-measured object can be improved.

It is a figure which shows the distortion measuring apparatus in embodiment of this invention. It is a perspective view which shows a part of distortion measuring apparatus in embodiment of this invention. It is sectional drawing which shows a part of distortion measuring apparatus in embodiment of this invention. It is a front view which shows the 1st apparatus in embodiment of this invention. It is a block diagram which shows the hardware of the strain meter in embodiment of this invention. It is a block diagram which shows the strain meter in embodiment of this invention.

  At least the following matters will become apparent from the description of this specification and the accompanying drawings.

=== Strain measuring device ===
Hereinafter, the strain measuring apparatus according to the present embodiment will be described with reference to FIGS. FIG. 1 is a diagram illustrating a strain measuring apparatus according to the present embodiment. In addition, the 1st electrode body 7 and the 2nd electrode body 3 are shown as sectional drawing in the cross section which passes through the approximate center of the 1st electrode body 7 and the 2nd electrode body 3, and is parallel to XZ plane (FIG. 3). . The configuration corresponding to the capacitance meter 5 is surrounded by a one-dot chain line. Conductive lines surrounded by conductors such as coaxial cables are indicated by broken lines. FIG. 2 is a perspective view showing a part of the strain measuring apparatus in the present embodiment. In FIG. 2, for convenience of explanation, the first coaxial cable 93, the second coaxial cable 91, the adjusting screw 86 (FIG. 4), etc. are omitted.

  The strain measuring device 100 is a device for measuring the amount of strain in a welded portion of a boiler, a turbine, a pipe or the like provided in, for example, a thermal power plant. Note that the strain amount indicates, for example, the amount of displacement of the measurement object according to the deformation of the measurement object. The strain measuring device 100 is a capacitance type device for measuring a strain amount of a measurement target portion 401 such as a welded portion in a metal pipe 400 (measurement object) having a relatively high temperature of, for example, 600 ° C. or higher. Displacement meter.

  The strain measuring device 100 includes a first device 800 (FIG. 2), a second device 200, a capacitance meter 5 (first measuring device), and a strain meter 4 (second measuring device). In the present embodiment, the Z axis is an axis along the height direction (vertical direction) where the first device 200 and the second device 800 are erected, and + Z is an upward direction from the pipe 400 toward the first device 800. A direction is indicated, and −Z indicates a downward direction from the first device 800 toward the pipe 400. The X axis is an axis along the direction in which the first device 800 and the second device 200 are adjacent to each other, + X indicates the direction from the second device 200 toward the first device 800, and -X is the first device. It is assumed that the direction from 800 toward the second device 200 is shown. The Y axis is an axis orthogonal to the X axis and the Z axis, and + Y is from one side surface of the first device 800 where the slit 8B is provided to the other side surface where the slit 8B is not provided. The direction to go is shown, -Y shall show the direction which goes to the one side surface from the other side surface in the 2nd apparatus 200. As shown in FIG.

  When the first device 800 and the second device 200 measure the strain amount of the measurement target portion 401 in the metal pipe 400, the first device 800 and the second device 200 are arranged on both sides of the measurement target portion 401 in the direction (X axis) in which the pipe 400 extends. Provided. The first device 800 and the second device 200 function as sensors for measuring the strain amount in the direction in which the pipe 400 extends in the measurement target portion 401 (longitudinal direction of the pipe 400).

  The capacitance meter 5 is, for example, an LCR meter for measuring the capacitance of a capacitor formed by the rod-shaped electrode 32 and the cylindrical electrode 72 (also referred to as “a capacitor formed by electrodes”).

  The strain meter 4 measures the strain amount of the measurement target portion 401 based on the measurement result of the capacitance meter 5.

=== first device, second device ===
Hereinafter, the first device and the second device in the present embodiment will be described with reference to FIGS. 1 to 4. FIG. 3 is a cross-sectional view showing a part of the strain measuring apparatus according to the present embodiment. FIG. 3 shows the first device 800 and the second device 200 in the state viewed from the XZ plane passing through the approximate center of the first device 800 in FIG. 2 toward the + Y direction. In FIG. 3, the adjusting screw 86 (FIG. 4) is omitted for convenience of explanation. FIG. 4 is a front view showing the first device in the present embodiment.

= First device =
The first device 800 is fixed by welding, for example, on the + X side of the measurement target portion 401 in the pipe 400. The first device 800 includes a first attachment device 8 and a first electrode body 7.

<First mounting device>
The first attachment device 8 is a device for attaching the first electrode body 7 to the pipe 400 and is fixed to the pipe 400. The first attachment device 8 includes a first metal member 81, first insulating members 82 and 83, a metal leg 85, and an adjusting screw 86 (FIG. 4).

  The first metal member 81 is disposed between the first insulating members 82 and 83 and the pipe 400 so that the rod-shaped electrode 32 is inserted into the cylindrical electrode 72 in order to attach the first electrode body 7 to the pipe 400. The first insulating members 82 and 83 are surrounded.

  The first metal member 81 has a slit 8B and screw holes 81A and 81B. The slit 8 </ b> B is a gap for deforming the metal member 81. The screw holes 81A and 81B are provided along the Z axis on the side (-Y) where the slit 8B is provided in the first metal member 81.

  Legs 25 are welded to, for example, the four corners of the bottom surface (-Z) of the first metal member 81. The leg 25 is welded to the pipe 400, for example. That is, the metal member 21 is firmly fixed to the pipe 400 by the legs 25.

  The first insulating members 82 and 83 are a pair of insulating members such as ceramics for electrically insulating the first electrode body 7 from the pipe 400. The first insulating members 82 and 83 are fixed inside the first metal member 81. The first insulating members 82 and 83 are fixed to the upper and lower sides in the Z axis, respectively.

  The adjusting screw 86 is used to deform the first metal member 81 in order to hold the first electrode body 7. The adjusting screw 86 is continuously screwed into the screw holes 81A and 81B. When the width of the slit 8 </ b> B in the Z-axis direction is narrowed by the adjusting screw 86, the first electrode body 7 provided inside the first metal member 81 is sandwiched between the first insulating members 82 and 83. The first electrode body 7 is attached to the pipe 400 by the first attachment device 8.

<First electrode body>
The first electrode body 7 includes a first case 71, a cylindrical electrode 72, and a first support member 73.

  The first case 71 is, for example, a metal housing that houses the cylindrical electrode 72. The external shape of the first case 71 has, for example, a cylindrical shape. The first case 71 has a hollow structure so that the cylindrical electrode 72 can be accommodated therein. Note that the length of the first case 71 in the X-axis direction is longer than the length of the cylindrical electrode 72 in the X-axis direction so that the entire cylindrical electrode 72 can be accommodated. The inner diameter of the first case 71 is larger than the outer diameter of the cylindrical electrode 72.

  The first case 71 has a first opening 74 (first insertion hole) and a second opening 75.

  One end of the first coaxial cable 93 is inserted into the first opening 74. The first opening 74 is provided on the opposite side (+ X) to the second electrode body 3 side (−X). The second opening 75 communicates with the inside of the cylindrical electrode 72. The second opening 75 is provided on the second electrode body 3 side. The diameter of the second opening 75 is larger than the diameter of the rod-shaped electrode 32 so that the rod-shaped electrode 32 is inserted into the cylindrical electrode 72 through the second opening 75.

  The first support member 73 supports the cylindrical electrode 72 inside the first case 71 so that the cylindrical electrode 72 does not contact the first case 71. The first support member 73 is an insulating member such as ceramics. The first support member 73 may be provided in the entire interior of the first case 71.

  The cylindrical electrode 72 is a metal member for forming a capacitor together with the rod-shaped electrode 32. The cylindrical electrode 72 extends along the longitudinal direction (X axis) of the pipe 400. The cylindrical electrode 72 is inserted so that the rod-shaped electrode 32 can advance and retreat along the X axis. The cylindrical electrode 72 is fixed inside the first case 71 by the first support member 73 so as not to contact the first case 71.

= Second device =
The second device 200 is fixed by welding, for example, closer to the −X side than the measurement target portion 401 in the pipe 400. The second device 200 includes a second attachment device 2 and a second electrode body 3.

<Second mounting device>
The second attachment device 2 is a device for attaching the second electrode body 3 to the pipe 400 and is fixed to the pipe 400.

  The configuration of the second mounting device 2 is the same as the configuration of the first mounting device 8. That is, the second metal member 21, the second insulating members 22 and 23, the adjusting screw (not shown), and the legs 25 in the second attachment device 2 are configured with the first metal member 81, the first insulating members 82 and 83, The configuration is the same as that of the adjusting screw 86 and the leg 85.

<Second electrode body>
The second electrode body 3 includes a second case 31, a rod-shaped electrode 32, and a second support member 33.

  The second case 31 is, for example, a metal housing that houses a part of the rod-shaped electrode 32. The external shape of the second case 31 has, for example, a cylindrical shape. The second case 31 has a hollow structure so that a part of the rod-shaped electrode 32 can be accommodated therein. The inner diameter of the second case 31 is made larger than the outer diameter of the rod electrode 32.

  The second case 31 has a first opening 34 (second insertion hole) and a second opening 35.

  One end of the second coaxial cable 91 is inserted into the first opening 34. The first opening 34 is provided on the side (−X) opposite to the first electrode body 7 side (+ X). A rod-shaped electrode 32 protrudes from the second opening 35. The second opening 35 is provided on the first electrode body 7 side.

  The second support member 33 supports the rod-shaped electrode 32 inside the second case 31 so that the rod-shaped electrode 32 does not contact the second case 31. The second support member 33 is an insulating member such as ceramics. The second support member 33 may be provided in the entire interior of the second case 31.

  The rod-shaped electrode 32 is a metal member for forming a capacitor together with the cylindrical electrode 72. The rod-shaped electrode 32 extends along the longitudinal direction (X axis) of the pipe 400. The rod-shaped electrode 32 is inserted into the cylindrical electrode 72 so as to be movable back and forth along the X axis. The rod-shaped electrode 32 is fixed inside the second case 31 by the second support member 33 so as not to contact the second case 31. The rod-shaped electrode 32 has a cylindrical shape, for example.

<Capacitance of capacitor>
The capacitance value of the capacitor formed by the rod-shaped electrode 32 and the cylindrical electrode 72 depends on the distance D1 between the first device 800 and the second device 200 in the direction (X axis) in which the pipe 400 extends. Will be determined. That is, the capacitance value of the capacitor is determined according to the length of the portion of the rod-like electrode 32 inserted into the cylindrical electrode 72. Therefore, it is possible to obtain the fluctuation of the distance D1 based on the fluctuation of the capacitance value of the capacitor. That is, it is possible to obtain the amount of strain in the direction (X axis) in which the rod-shaped electrode 32 in the measurement target portion 401 is inserted into the cylindrical electrode 72 based on the variation in the capacitance value of the capacitor.

=== Capacitance meter ===
Hereinafter, the capacity meter in the present embodiment will be described with reference to FIG.

  The capacitance meter 5 is a device that measures the capacitance of a capacitor formed by electrodes based on a four-terminal pair measurement method based on an automatic balance bridge method.

  The capacitance meter 5 includes a voltage source 513, a voltmeter 523, an amplifier 533, an ammeter 543, conductive wires 511, 521, 531, 541, and conductors 512, 522, 532, 542.

  One end of each of the conductive lines 511 and 521 is connected to each other at the connection point P1 via the conductive lines 611 and 621 of the T-type BNC connector 61.

  The conductors 512 and 522 are provided around the conductive lines 511 and 521, respectively. The conductors 512 and 522 are connected to each other via the conductors 612 and 622 of the T-type BNC connector 61. The conductors 612 and 622 are provided around the conductive wires 611 and 621.

  The other end of the conductive wire 511 is connected to the conductor 512 via the voltage source 513. The other end of the conductive wire 521 is connected to the conductor 522 via the voltmeter 523.

  One end of each of the conductive lines 531 and 541 is connected to each other at the connection point P3 via the conductive lines 631 and 641 of the T-type BNC connector 63.

  The conductors 532 and 542 are provided around the conductive lines 531 and 541, respectively. The conductors 532 and 542 are connected to each other via the conductors 632 and 642 of the T-type BNC connector 63. The conductors 632 and 642 are provided around the conductive lines 631 and 641.

  The other end of the conductive line 531 is connected to one input of the amplifier 533. The other input of the amplifier 533 is connected to the conductor 532. The other end of the conductive wire 541 is connected to the conductor 542 through an ammeter 543.

  A voltage source (not shown) is provided between the ammeter 543 and the conductor 542, and the output of this voltage source is that of the amplifier 533 so that the voltage at the connection point P3 is approximately 0 V (virtual ground). Control is based on the output.

  The capacitance meter 5 measures the capacitance of the capacitor formed by the electrodes based on the output voltage of the voltage source 513, the measurement results of the voltmeter 523 and the ammeter 543, and outputs measurement information indicating the measurement results.

=== Connection between capacitance meter and electrode body ===
Hereinafter, the connection between the capacitance meter and the electrode body in the present embodiment will be described with reference to FIG.

  The first electrode body 7 is connected to the capacitance meter 5 via the first coaxial cable 93 and the T-type BNC connector 63. The second electrode body 3 is connected to the capacity meter 5 via the second coaxial cable 91 and the T-type BNC connector 61. The first electrode body 7 and the second electrode body 3 are connected to each other via a conductive cable 900.

<Each cable>
The first coaxial cable 93 is a heat resistant cable having a conductive wire 931 and a conductor 932 provided around the conductive wire 931. The second coaxial cable 91 is a heat resistant cable having a conductive wire 911 and a conductor 912 provided around the conductive wire 911. The first coaxial cable 93 and the second coaxial cable 91 may be, for example, inorganic insulation cables, that is, MI (Mineral Insulation) cables.

  The conductive cable 900 is a heat resistant cable having at least a conductive wire. The conductive cable 900 may be an MI cable similar to the first coaxial cable 93 or the like, for example.

<Connection>
One end of the conductive wire 931 in the first coaxial cable 93 is connected to the cylindrical electrode 72. The other end of the conductive line 931 is connected to both the conductive lines 641 and 631 at the connection point P3. With these connections, the cylindrical electrode 72 is connected to the connection point P3. The conductor 932 in the first coaxial cable 93 is connected to the first case 71 via the electric path 939. With this connection, the first case 71 is connected to both the conductors 532 and 542 in the capacitance meter 5. The electric path 939 may be formed by welding the conductor 932 to the first case 71.

  One end of the conductive wire 911 in the second coaxial cable 91 is connected to the rod-shaped electrode 32. The other end of the conductive line 911 is connected to both the conductive lines 611 and 621 at the connection point P1. With these connections, the rod-shaped electrode 32 is connected to the connection point P1. The conductor 912 in the second coaxial cable 91 is connected to the second case 31 via the electric path 919. With this connection, the second case 31 is connected to both the conductors 512 and 522 in the capacitance meter 5. The electric path 919 may be formed by welding the conductor 912 to the second case 31.

  Note that one end of each of the first coaxial cable 93 and the second coaxial cable 91 is inserted into the first openings 74 and 34, respectively. Therefore, the first support member for each of the first coaxial cable 93 and the second coaxial cable 91 is used. 73, the fixing strength with respect to the second support member 33 is improved.

  Both ends of the conductive cable 900 are connected to the first case 71 and the second case 31 so that the first case 71 and the second case 31 are electrically connected. By this connection, the conductors 512, 522, 532, and 542 in the capacitance meter 5 are connected to each other. Note that both ends of the conductive cable 900 may be welded and connected to the first case 71 and the second case 31, respectively. Therefore, when the capacitance meter 5 measures the capacitance of the capacitor formed by the electrodes, the conductors 512, 522, 612, 622, 912, the electric circuit 919, the second case 31, the conductive wire 900, the first case 71, the electric circuit 939. The guard current can be passed through the conductors 932, 632, 642, 532, 542. For this reason, the measurement accuracy of the capacitance of the capacitor formed by the electrode of the capacitance meter 5 can be improved.

  For example, a predetermined test fixture may be provided between the capacity meter 5 and the T-type BNC connectors 61 and 63.

=== Strain meter ===
Hereinafter, with reference to FIG.5 and FIG.6, the strain meter in this embodiment is demonstrated. FIG. 5 is a block diagram showing hardware of the strain gauge in the present embodiment. FIG. 6 is a block diagram showing a strain gauge in the present embodiment.

  The strain gauge 4 includes a CPU (Central Processing Unit) 41, a communication device 42, a storage device 43, a display device 44, and an input device 45. The CPU 41 implements various functions of the strain gauge 4 by executing a program stored in the storage device 43 and controls the strain gauge 4 in an integrated manner. The storage device 43 stores the above-described program and various types of information. The display device 44 is a display that displays information of the strain gauge 4. The input device 45 is, for example, a keyboard or a mouse for inputting information to the strain gauge 4. The communication device 42 communicates with the capacity meter 5.

  The strain gauge 4 further includes a strain measurement unit 46 and a control unit 47 (also referred to as “various functions of the strain gauge 4”). The various functions of the strain gauge 4 are realized by the CPU 41 executing programs stored in the storage device 43.

  The strain measurement unit 46 calculates the strain of the pipe 400 from the capacitance value of the capacitor formed by the electrodes based on the measurement information received from the capacitance meter 5, and outputs or displays the calculation result. In addition, for example, strain information indicating the relationship between the capacitance value of the capacitor formed by the electrode and the strain amount of the pipe 400 is included in various types of information. The distortion may be calculated. The control unit 47 controls the capacity meter 5.

  The strain meter 4 controls the capacitance meter 5 so that the capacitance meter 5 measures the capacitance value of the capacitor formed by the electrodes. Thereafter, the strain meter 4 receives the measurement information from the capacitance meter 5 and calculates the strain of the pipe 400 based on the received measurement information.

  As described above, the strain measuring apparatus 100 includes the first electrode body 7, the second electrode body 3, and the strain gauge 4. The first electrode body 7 includes a cylindrical electrode 72, a first case 71, and a first support member 73, and is attached to the pipe 400. The first case 71 has a larger inner diameter than the outer diameter of the cylindrical electrode 72 and is a metal case that accommodates the cylindrical electrode 72. The first support member 73 is an insulating member that supports the cylindrical electrode 72 inside the first case 71 so that the cylindrical electrode 72 does not contact the first case 71. The second electrode body 3 includes a rod-shaped electrode 32, a second case 31, and a second support member 33, and is attached to the pipe 400. The rod-shaped electrode 32 is inserted into the cylindrical electrode 72. The second case 31 is a metal case that has an inner diameter larger than the outer diameter of the rod-shaped electrode 32 and accommodates the rod-shaped electrode 32 so that the rod-shaped electrode 32 is inserted into the cylindrical electrode 72. The second support member 33 is an insulating member that supports the rod-shaped electrode 32 inside the second case 31 so that the rod-shaped electrode 32 does not contact the second case 31. In the strain gauge 4, the rod-shaped electrode 32 in the pipe 400 is inserted based on the measurement result of the capacitance meter 5 that measures the capacitance determined according to the length of the portion of the rod-shaped electrode 32 inserted into the cylindrical electrode 72. The amount of strain in the direction (X axis) is measured. The capacitance meter 5 includes conductive wires 511, 521, 531, 541 and conductors 512, 522, 532, 542. One end of the conductive line 511 is connected to the voltage source 513. The conductor 512 is provided around the conductive wire 511. One end of the conductive line 521 is connected to a voltmeter 523. The conductor 522 is provided around the conductive wire 521 and is connected to the conductor 512. One end of the conductive line 531 is connected to the amplifier 533. The conductor 532 is provided around the conductive wire 531. One end of the conductive wire 541 is connected to an ammeter 543. The conductor 542 is provided around the conductive wire 541 and connected to the conductor 532. The cylindrical electrode 72 is connected to the other ends of the conductive wires 531 and 541. The rod-shaped electrode 32 is connected to the other ends of the conductive wires 511 and 521. The first case 71 is connected to the conductors 532 and 542. The second case 31 is connected to the conductors 512 and 522. The first case 71 and the second case 31 are connected to each other so that the conductors 532 and 542 and the conductors 512 and 522 are connected. Therefore, as described above, the guard current can flow. Therefore, by reducing the capacitance value of the stray capacitance, the capacitance measurement accuracy by the capacitance meter 5 can be improved for the capacitor formed by the electrodes. Therefore, the measurement accuracy of the strain of the pipe 400 by the strain measuring device 100 can be improved.

  The first case 71 and the second case 31 are connected by a conductive cable 900. Both ends of the conductive cable 900 are welded to the first case 71 and the second case 31 so that the first case 71 and the second case 31 are connected to each other. For example, by accurately connecting the first case 71 and the second case 31 that have a relatively high temperature such as 600 ° C. or higher, the strain measurement accuracy of the pipe 400 by the strain measuring device 100 can be improved.

  The first case 71 and the second case 31 are arranged in the direction (X axis) in which the rod-shaped electrode 32 is inserted. Both ends of the conductive cable 900 are welded to the + X side end of the first case 71 and the −X side end of the second case 31, respectively. Therefore, for example, the conductive cable 900 can be prevented from being bent between the first case 71 and the second case 31 and coming into contact with the rod-shaped electrode 32. Therefore, the measurement error of the capacitance meter 5 due to the conductive cable 900 coming into contact with the rod-shaped electrode 32 can be reduced.

  The first coaxial cable 93 is connected between the first electrode body 7 and the capacitance meter 5. The second coaxial cable 91 is connected between the second electrode body 3 and the capacitance meter 5. The cylindrical electrode 72 is connected to the conductive lines 531 and 541 through the conductive line 931. The rod-shaped electrode 32 is connected to the conductive lines 511 and 521 through the conductive line 911. The first case 71 is connected to the conductors 532 and 542 through the conductor 932 of the first coaxial cable 93. The second case 31 is connected to the conductors 512 and 522 through the conductor 912 of the second coaxial cable 91. Accordingly, stray capacitance generated in the cable connected between the first electrode body 7 and the second electrode body 3 and the capacitance meter 5 can be reduced. Therefore, the measurement accuracy of the capacity meter 5 can be improved.

  The first coaxial cable 93 is attached to the first case 71 with one end of the first coaxial cable 93 inserted into the first opening 74. The second coaxial cable 91 is attached to the second case 31 with one end of the second coaxial cable 91 inserted into the first opening 34. Therefore, the first coaxial cable 93 and the second coaxial cable 91 can be reliably connected to the first case 71 and the second case 31, respectively. Therefore, the measurement accuracy of the capacity meter 5 can be further improved.

  The strain measuring apparatus 100 includes first insulating members 82 and 83, a first metal member 81, second insulating members 22 and 23, and a second metal member 21. The first insulating members 82 and 83 surround the first electrode body 7 so that the rod-shaped electrode 32 is inserted into the cylindrical electrode 72. The second insulating members 22 and 23 surround the second electrode body 3 so that the rod-shaped electrode 32 is inserted into the cylindrical electrode 72. The first metal member 81 has a first insulation between the first insulating member 83 and the pipe 400 so that the rod-shaped electrode 32 is inserted into the cylindrical electrode 72 in order to attach the first electrode body 7 to the pipe 400. The members 82 and 83 are surrounded. The second metal member 21 has a second insulation between the second insulating member 23 and the pipe 400 so that the rod-like electrode 32 is inserted into the cylindrical electrode 72 in order to attach the second electrode body 3 to the pipe 400. The members 22 and 23 are surrounded. Therefore, when measuring the capacitor formed by the electrodes, for example, the leakage current supplied from the cylindrical electrode 72 and the rod-shaped electrode 32 to the pipe 400 can be reduced. Therefore, the measurement accuracy of the capacity meter 5 can be further improved.

  Further, the leg 85 protrudes from the first metal member 81 toward the pipe 400 between the pipe 400 and the first metal member 81. The legs 85 are metal legs that are fixed to the pipe 400. The legs 25 protrude from the second metal member 21 toward the pipe 400 between the pipe 400 and the second metal member 21. The legs 25 are metal legs that are fixed to the pipe 400. Therefore, the first electrode body 7 and the second electrode body 3 can be reliably fixed to the pipe 400.

  The legs 25 and 85 are fixed to both sides of the measurement target portion 401 in the pipe 400. Accordingly, it is possible to measure the distortion of the measurement target portion 401 that may be relatively distorted in the pipe 400.

  Moreover, the steam heated by the boiler is let through the piping 400, for example. The conductive cable 900 is, for example, an MI cable made of a heat resistant material. Therefore, the first case 71 and the second case 31 can be reliably connected even at a relatively high temperature.

  The first support member 73 and the second support member 33 are made of ceramics. Therefore, the cylindrical electrode 72 and the rod-shaped electrode 32 can be reliably supported so that the cylindrical electrode 72 and the rod-shaped electrode 32 are electrically insulated from the first case 71 and the second case 31, respectively.

  In addition, the said embodiment is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

  In the present embodiment, one end of the conductive wire 931 in the first coaxial cable 93 is connected to the cylindrical electrode 72, and one end of the conductive wire 911 in the second coaxial cable 91 is connected to the rod-shaped electrode 32. However, the present invention is not limited to this. For example, one end of the conductive wire 931 may be connected to the rod-shaped electrode 32, and one end of the conductive wire 911 may be connected to the cylindrical electrode 72. In this case, the conductor 932 is connected to the second case 31, and the conductor 912 is connected to the first case 71.

3 Second electrode body 4 Strain meter 5 Capacitance meter 7 First electrode body 31 Second case 32 Rod electrode 71 First case 72 Cylindrical electrode 100 Strain measuring device 400 Piping 900 Conductive cable

Claims (9)

A cylindrical electrode, a first case made of metal having an inner diameter larger than an outer diameter of the cylindrical electrode, and housing the cylindrical electrode, and the cylindrical electrode are not in contact with the first case A first electrode body that has an insulating first support member that supports the cylindrical electrode inside the first case, and is attached to the object to be measured;
A rod-shaped electrode inserted into the cylindrical electrode, and a metal second electrode having an inner diameter larger than the outer diameter of the rod-shaped electrode and accommodating the rod-shaped electrode so that the rod-shaped electrode is inserted into the cylindrical electrode. A case and an insulating second support member that supports the rod-shaped electrode inside the second case so that the rod-shaped electrode does not contact the second case, and is attached to the object to be measured. A second electrode body;
Based on the measurement result of the first measuring device that measures the capacitance determined according to the length of the portion of the rod-shaped electrode inserted into the cylindrical electrode, the rod-shaped electrode in the object to be measured is inserted. A second measuring device for measuring the amount of strain in the direction,
The first measuring device includes:
A first conductive line having one end connected to the voltage source;
A first conductor provided around the first conductive line;
A second conductive wire having one end connected to the voltmeter;
A second conductor provided around the second conductive line and connected to the first conductor;
A third conductive line having one end connected to the amplifier;
A third conductor provided around the third conductive line;
A fourth conductive line having one end connected to the ammeter, and a fourth conductor provided around the fourth conductive line and connected to the third conductor;
One of the cylindrical electrode and the rod-shaped electrode is connected to the other end of the first and second conductive wires,
The other electrode of the cylindrical electrode and the rod-shaped electrode is connected to the other end of the third and fourth conductive wires, and one case that houses the one electrode of the first and second cases Is connected to the first and second conductors,
The other of the first and second cases is connected to the third and fourth conductors,
A conductive cable connected between the first and second cases, and the first and second cases are connected to each other at both ends of the conductive cable. A strain measuring device which is welded to The first and second cases are arranged in a direction in which the rod-shaped electrode is inserted,
One end of the conductive cable is welded to the end of the first case opposite to the second case,
The strain measuring device according to claim 1 , wherein the other end of the conductive cable is welded to an end of the second case opposite to the first case. A first coaxial cable connected between one electrode body having the one of the first and second electrode bodies and the first measuring device;
A second coaxial cable connected between the other of the first and second electrode bodies and the first measuring device; and
The one electrode is connected to the other ends of the first and second conductive lines via a fifth conductive line of the first coaxial cable,
The other electrode is connected to the other ends of the third and fourth conductive lines via a sixth conductive line of the second coaxial cable;
The one case is connected to the first and second conductors via a fifth conductor of the first coaxial cable surrounding the fifth conductive line,
The strain measurement according to claim 1, wherein the other case is connected to the third and fourth conductors via a sixth conductor of the second coaxial cable surrounding the sixth conductive line. apparatus. The one case is provided with a first insertion hole into which an end of the first coaxial cable is inserted,
The other case is provided with a second insertion hole into which an end of the second coaxial cable is inserted,
The first coaxial cable is attached to the one case with the end of the first coaxial cable being inserted into the first insertion hole,
The strain measuring apparatus according to claim 3 , wherein the second coaxial cable is attached to the other case in a state where an end of the second coaxial cable is inserted into the second insertion hole. . A first insulating member surrounding the first electrode body so that the rod-shaped electrode is inserted into the cylindrical electrode;
A second insulating member surrounding the second electrode body so that the rod-shaped electrode is inserted into the cylindrical electrode;
Around the first insulating member between the first insulating member and the device under test so that the rod-shaped electrode is inserted into the cylindrical electrode in order to attach the first electrode body to the device under test. A first metal member surrounding
In order to attach the second electrode body to the object to be measured, the second insulating member is interposed between the second insulating member and the object to be measured so that the rod electrode is inserted into the cylindrical electrode. The strain measuring apparatus according to claim 1 , further comprising: a second metal member surrounding the periphery. A metal first leg that protrudes from the first metal member toward the object to be measured between the object to be measured and the first metal member, and is fixed to the object to be measured;
A metal second leg that protrudes from the second metal member toward the object to be measured between the object to be measured and the second metal member, and is fixed to the object to be measured. The strain measuring apparatus according to claim 5 , wherein the apparatus is a strain measuring apparatus. The object to be measured includes a first pipe and a second pipe welded to the first pipe.
The first leg is fixed to the first pipe;
The strain measuring apparatus according to claim 6 , wherein the second leg is fixed to the second pipe. The first and second pipes pass steam heated by a boiler,
The strain measuring device according to claim 7 , wherein the conductive cable is made of a heat-resistant material. The strain measuring apparatus according to claim 1, wherein the first and second support members are made of ceramics.

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