In-pipe inspection device

Abstract

To provide an in-pipe inspection device capable of easily and accurately sensing a bending angle between two joined pipes being passed through an existing pipe.SOLUTION: An in-pipe inspection device provided herein comprises multiple displacement meters 2 fixed to one pipe 4, 5 of two joined pipes 4, 5 to be inserted into an existing pipe P, and a target 3 fixed to the other pipe 4, 5 of the joined pipes 4, 5 in such a way that a probe of each displacement meter 2 comes into contact therewith, where the device is configured to compute a bending angle θ between the joined pipes 4, 5 from the amount of displacement of each displacement meter 2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an in-pipe inspection device for pre-investigating whether a new pipe can be inserted into an existing pipe or the like by the pipe-in-pipe method prior to the installation work of fluid transport pipes such as water pipes.

Background Art

[0002] In the pipe-in-pipe method of inserting a new pipe (such as a ductile iron pipe (PN pipe, PII pipe, etc.)) into an existing pipe (sheath pipe) to construct a new pipeline in the deteriorated existing pipe, a pre-investigation may be conducted before actual construction to confirm whether the new pipe can be inserted smoothly. As one of the pre-investigation methods, two simulated pipes simulating the new pipe to be actually inserted are joined, and the joined simulated pipes are pulled into the existing pipe by a wire or the like pulled by a winch, and it is investigated whether the simulated pipes can pass smoothly from the starting shaft to the arrival shaft.

[0003] In the above pre-investigation method, although it is possible to determine whether the joined simulated pipes can pass, the bending angle of the pipeline of the existing pipe cannot be grasped in detail. The thrust is transmitted through the lock ring in the joined pipe body, but the allowable thrust is determined by the bending angle of the new pipe, and when the bending angle is large, an excessive thrust cannot be loaded. Therefore, when the bending angle cannot be grasped in detail, in order to withstand a predetermined magnitude of thrust required for the propulsion of the pipe body, it is necessary to adopt a reinforced pipe such as a welded-ring pipe or a flange-ribbed pipe in view of safety, which may result in high costs.

[0004] In order to investigate the bending angle in the existing pipe, for example, in the pipeline shape measuring device described in Patent Document 1 below, a first cylindrical case 1 and a second cylindrical case 2 passed through the pipeline 4 are connected by a universal joint portion 7. This universal joint portion 7 has rotation position detectors 8a and 8b, and the bending angle and its direction of the cylindrical case 1 with respect to the cylindrical case 2 are detected by these rotation position detectors 8a and 8b (see, for example, FIG. 2 of Patent Document 1).

[0005] In addition, in the bending angle measuring device described in Patent Document 2 below, a first unit 4 and a second unit 5 provided in the existing pipe 1 are connected via a telescopic ram 6 and universal joints 7 and 8. Bending angle measuring devices 10 and 11 are provided in parallel with each of the universal joints 7 and 8, and the three-dimensional bending angle at the joint portion 2 of the existing pipe 1 is obtained from data such as this bending angle measuring device (see FIG. 1 of Patent Document 2, etc.).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the configuration according to Patent Document 1, the bending angle of the existing pipe (pipe line) is detected by freely bending between the two cylindrical cases 1 and 2, and in the configuration according to Patent Document 2, the bending angle of the existing pipe is detected by freely bending between the two units 4 and 5. However, in the actual connected pipe body, there is a possibility that the bending angle is restricted, or a deviation may occur between the bending angle between the pipe bodies and the bending angle of the existing pipe when the pipe lengths of the existing pipe and the new pipe are different. For this reason, there is a problem that it is difficult to accurately determine the allowable thrust determined based on the bending angle between the pipe bodies.

[0008] Therefore, an object of the present invention is to simply and accurately detect the bending angle between pipe bodies when the connected pipe body is passed through the existing pipe.

Means for Solving the Problems

[0009] To solve the above problems, in the present invention, a plurality of displacement gauges fixed to one of the connected pipe bodies inserted into the existing pipe, and It has a target fixed to the other tubular body of the connected tubular bodies, against which the detection probes of the respective displacement gauges abut. A pipe inspection device is configured to calculate the bending angle between the connected tubular bodies from the displacement amounts of the respective displacement gauges.

[0010] In this way, the bending angle between the connected tubular bodies can be detected simply and accurately, so that an appropriate tubular body corresponding to the bending angle can be selected, and it is possible to prevent excessive cost.

[0011] In the above configuration, One of the plurality of displacement gauges is provided to measure displacement in a direction inclined with respect to the axial direction of the one tubular body, and the other of the plurality of displacement gauges is provided to measure displacement in a direction inclined with respect to both the axial direction of the one tubular body and the displacement measurement direction of the one displacement gauge.

[0012] In this way, the inclination angle between the tubular bodies can be easily calculated based on the displacements measured by the respective displacement gauges having different inclination directions.

[0013] In the configuration in which the displacement gauge is inclined, The one displacement gauge is provided to measure displacement in a direction orthogonal to the axial direction of the one tubular body, and the other displacement gauge is provided to measure displacement in a direction orthogonal to both the axial direction of the one tubular body and the displacement measurement direction of the one displacement gauge. Let the axial distance from the pipe end of the other pipe body to the tip of the detection probe of the one displacement gauge be L1, the displacement amount of the detection probe of the one displacement gauge when the connected pipe body bends from the straight state be Δ1, the axial distance from the pipe end of the other pipe body to the tip of the detection probe of the other displacement gauge be L2, and the displacement amount of the detection probe of the other displacement gauge when the connected pipe body bends from the straight state be Δ2. Then, the inclination angle θ1 in the detection direction by the one displacement gauge, the inclination angle θ2 in the detection direction by the other displacement gauge, and the bending angle θ between the connected pipe bodies, which is the resultant angle of the two inclination angles θ1 and θ2, can be calculated by the following equations (1) to (3). Equation (1): θ1 = tan -1 (Δ1 / L1) Equation (2): θ2 = tan -1 (Δ2 / L2) Equation (3): θ = cos -1 (cosθ1 × cosθ2)

[0014] In this way, by applying the displacement amounts detected by each displacement gauge to the respective equations, the bending angle can be calculated smoothly.

[0015] In the configuration where the displacement gauge is inclined, instead of the above, the one displacement gauge is provided to measure the displacement in a direction perpendicular to the axial direction of the one pipe body, and the other displacement gauge is provided to measure the displacement in a direction perpendicular to both the axial direction of the one pipe body and the displacement measurement direction of the one displacement gauge. Furthermore, it further has a first parallel displacement gauge provided parallel to the axial direction of the one displacement gauge to measure the displacement in the same direction as the one displacement gauge, and another parallel displacement gauge provided parallel to the axial direction of the other displacement gauge to measure the displacement in the same direction as the other displacement gauge. Let the axial distance between the tips of the detection probes of the one displacement meter and the one parallel displacement meter be L1', the displacement difference between the one displacement meter and the one parallel displacement meter when the connected pipe body bends from a straight state be δ1, the axial distance between the tips of the detection probes of the other displacement meter and the other parallel displacement meter be L2', and the displacement difference between the other displacement meter and the other parallel displacement meter when the connected pipe body bends from a straight state be δ2. Then, the inclination angle θ1' in the detection direction by the one displacement meter, the inclination angle θ2' in the detection direction by the other displacement meter, and the combined angle θ' of the two inclination angles θ1' and θ2', which is the bending angle θ' between the connected pipe bodies, can be calculated by the following equations (4) to (6). (Equation (4): θ1' = tan -1 (δ1 / L1') (Equation (5): θ2' = tan -1 (δ2 / L2') (Equation (6): θ' = cos -1 (cosθ1' × cosθ2')

[0016] In this way, the eccentricity between the receiving port and the insertion port of the two connected pipe bodies can be offset from the difference in the displacement amounts of the two displacement meters arranged side by side in the axial direction of the pipe, so that the bending angle between the two pipe bodies can be detected more accurately.

[0017] In the above configuration, a rotation sensor for detecting rotation around the axis of the pipe can be provided on at least one of the connected pipe bodies.

[0018] In this way, even when the pipe body rotates (rolls) around the axis when inserting the connected pipe body into the existing pipe, the direction of the bending angle (combined angle) can be accurately detected based on the rotation amount detected by the rotation sensor.

[0019] In the above configuration, the plurality of displacement meters are three displacement meters provided to measure displacement in the axial direction at positions corresponding to the vertices of a right-angled isosceles triangle in a plane having the same plane normal as the axial direction of the one pipe body, The target is fixed so as to have a surface normal in the same direction as the axis of the other pipe body. The lengths X of the two equal sides of the right-angled isosceles triangle B and the displacement amounts Z in the pipe axis direction measured by the three displacement gauges A , Z B , Z C From these, the three-dimensional surface normal vector d of the surface containing the target is calculated by the following formula (7), and from this surface normal vector d and the three-dimensional surface normal vector n = (0, 0, 1) of the surface containing the right-angled isosceles triangle, the cosine of the bending angle θ between the connected pipe bodies can be calculated by the following formula (8). (7) Formula: Vector d = X B ·(Z A - Z B , Z A - Z C , X B ) (8) Formula: cosθ = X B ÷√{(Z A - Z B ) 2 +(Z A - Z C ) 2 +X B 2}

[0020] In this way, the bending angle of the surface containing the target can be directly calculated from the displacement amounts of the three displacement gauges. Moreover, by arranging the three displacement gauges at the positions of the respective vertices of the right-angled isosceles triangle, the coordinate values of the respective vertices are made common, and the surface normal vector d of the surface containing the target and the cosine of the connected bending angle θ can be calculated by a simple mathematical formula. Further, even when the installation positions of the respective displacement gauges deviate from the predetermined positions and an error occurs in the angle formed by the vectors of the two sides sandwiching the right angle of the right-angled isosceles triangle, the influence of the error on the calculation result can be minimized.

[0021] In the configuration where the three displacement gauges are arranged at the respective vertices of the right-angled isosceles triangle, The axial center of the one pipe body can be positioned inside each side of the right-angled isosceles triangle formed by the three displacement gauges.

[0022] By doing so, the bending angle of the surface including the target inclined with respect to the axial center can be detected with higher precision.

[0023] In the above configuration, It can be configured to further include a data processing unit that measures the insertion amount of the connected pipe body into the existing pipe and derives the relationship between the insertion amount and the bending angles θ, θ'.

[0024] By doing so, it becomes clear at which position and to what extent the existing pipe is bent, so that the work can be smoothly advanced based on the bending data when actually inserting the pipe body.

Advantages of the Invention

[0025] In this invention, since the in-pipe inspection device is configured as described above, the bending angle between the pipe bodies when the connected pipe body is passed through the existing pipe can be detected simply and accurately.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0027] The first embodiment of the in-pipe inspection device 1 according to the present invention is shown in FIGS. 1(a) and 1(b). This in-pipe inspection device 1 is a device for pre-investigating whether a new pipe can be inserted into an existing pipe P by the pipe-in-pipe method prior to the laying work of a fluid transportation pipe such as a water pipe. It has a plurality of displacement gauges 2 fixed to one of the connected pipe bodies inserted into the existing pipe P, and a target 3 fixed to the other of the connected pipe bodies, with the detection probes of each displacement gauge 2 contacting the target 3. FIGS. 1(a) and 1(b) show a state where the pipe bodies are in a straight state. In this embodiment, one of the pipe bodies is the receiving-side pipe body 4 and the other is the insertion-side pipe body 5, but it is also possible to make one of the pipe bodies the insertion-side pipe body 5 and the other the receiving-side pipe body 4.

[0028] The displacement gauge 2 has a main body portion and a rod-shaped detection probe that protrudes and retracts from this main body portion. This detection probe is biased in one direction in its longitudinal direction (the direction toward the target 3) by a biasing member (not shown). This detection probe is pushed into the main body portion side against the biasing force of the biasing member, and is configured to detect the displacement amount of the target 3 that abuts against the tip of the detection probe from the amount of pushing. An attachment jig 6 is provided on the main body portion, and the displacement gauge 2 is attached to the inner surface of the receiving port or near the inner surface of the receiving port of the receiving side pipe body 4 by this attachment jig 6.

[0029] In this embodiment, the attachment jig 6 is fixed at two locations at the bottom of the pipe on the inner surface of the receiving port and at a position approximately 90 degrees in the circumferential direction from the bottom of the pipe. One displacement gauge 2 (hereinafter referred to as the vertical displacement gauge 2a) attached to the attachment jig 6 fixed to the bottom of the pipe has its detection probe protruding and retracting in the vertical direction, and the other displacement gauge 2 (hereinafter referred to as the horizontal displacement gauge 2b) attached by the attachment jig 6 fixed at a position approximately 90 degrees in the circumferential direction from the bottom of the pipe is arranged such that its detection probe protrudes and retracts in the horizontal direction.

[0030] As the attachment jig 6, for example, a magnet stand with an arm that can be detachably attached to the inner surface of the pipe by magnetic force can be adopted. By changing the fixing position of the displacement gauge 2 to this arm, the displacement gauge 2 can be attached to a desired position inside the pipe regardless of the nominal diameter of the pipe.

[0031] The target 3 is a plate-shaped member in an L shape in side view, having a portion extending toward the center of the tube axis provided near the tip of the insertion port of the insertion-side tube body 5, and a portion extending along the tube axis direction from the end on the tube axis center side. This target 3 is fixed to the tube top at the tip of the insertion port and at a position 90 degrees in the circumferential direction from the tube top (about the 180-degree symmetric position of the fixing position of the mounting jig). The target 3a (hereinafter referred to as the vertical target 3a) fixed to the tube top has a portion extending along its tube axis direction in contact with the tip of the detection probe of the vertical displacement meter 2a. Further, the target 3b (hereinafter referred to as the horizontal target 3b) fixed at a position 90 degrees in the circumferential direction from the tube top has a portion extending along its tube axis direction in contact with the tip of the detection probe of the horizontal displacement meter 2b. This target 3 (3a, 3b) can be used regardless of the nominal diameter of the tube body.

[0032] In this way, by arranging each displacement meter 2 (2a, 2b) and each target 3 (3a, 3b), the vertical displacement amount associated with the bending of both tube bodies 4 and 5 can be detected from the pushing-in amount of the detection probe of the vertical displacement meter 2a, and the horizontal displacement amount associated with the bending of both tube bodies 4 and 5 can be detected from the pushing-in amount of the detection probe of the horizontal displacement meter 2b. The data of the displacement amounts detected by each displacement meter 2a, 2b are stored in the data logger 7 provided in the tube bodies 4, 5.

[0033] At the front end of the receiving-side tube body 4 on the front side in the advancing direction of this in-pipe inspection device 1, a tip member 8 obtained by cutting a straight pipe portion of a tube body having the same shape as this receiving-side tube body 4 into a short length is connected. This tip member 8 has a function as a spacer for preventing the insertion port side of the receiving-side tube body 4 from tilting downward due to its own weight, and a function as a friction reduction member (sole) for reducing the friction between the insertion port side and the inner surface of the existing pipe P.

[0034] A rotation sensor 9 for detecting the amount of rotation (rolling amount) around the pipe axes of the connected pipes 4 and 5 is provided at the pipe top of the receiving-side pipe body 4. Even when rolling occurs in the pipes 4 and 5 during the insertion of the in-pipe inspection device 1, the displacement amounts detected by the respective displacement gauges 2 (2a, 2b) are corrected based on the amount of rotation detected by this rotation sensor 9, so that the bending angle and bending direction between the connected pipes 4 and 5 can be accurately grasped.

[0035] A locking member 10 is fixed to the receiving port of the inserting-side pipe body 5, and a traction member 11 is provided on this locking member 10. By pulling this traction member 11, the in-pipe inspection device 1 can be moved forward.

[0036] A winding type distance meter 13 for detecting the moving distance of the in-pipe inspection device 1 from the payout length of the wire 12 is provided in the connected pipes 4 and 5. One end of the wire 12 of this winding type distance meter 13 is fixed to the starting shaft pit (not shown) side, and as the in-pipe inspection device 1 moves toward the arrival shaft pit (not shown) side, the wound wire 12 is paid out. The data of the payout amount of the wire 12 is stored in the data logger 7.

[0037] This data logger 7 has a function as a data processing unit for deriving the relationship between the insertion amount and the bending angle of the in-pipe inspection device 1 based on the data of the payout amount of the wire 12, the data of the displacement amounts detected by the respective displacement gauges 2 (2a, 2b), and the amount of rotation detected by the rotation sensor 9. Based on the data such as the bending position and bending angle obtained by this data logger 7, an appropriate pipe type can be selected from various options such as normal pipes, pipes with welding rings, and pipes with flange ribs. In the following, the illustrations of the data logger 7, rotation sensor 9, traction member 11, and winding type distance meter 13 are appropriately omitted.

[0038] When the in-pipe inspection device 1 is inserted into the existing pipe P, the state in which the pipe bodies 4 and 5 are bent is shown in Figs. 2(a) and 2(b). Let the axial distance of the pipe from the pipe end of the inserting pipe body 5 to the tip of the detection probe of the vertical displacement meter 2a in the state where the pipe bodies 4 and 5 are straight (see Figs. 1(a) and 1(b)) be L1, and let the protruding length of the detection probe of the vertical displacement meter 2a that contacts the vertical target 3a be L 11 and the protruding length of the detection probe of the horizontal displacement meter 2b that contacts the horizontal target 3b be L 12 Also, when the pipe bodies 4 and 5 are bent, let the protruding length of the detection probe of the vertical displacement meter 2a that contacts the vertical target 3a be L 21 and the protruding length of the detection probe of the horizontal displacement meter 2b that contacts the horizontal target 3b be L 22 At this time, the displacement amount Δ1 of the detection probe of the vertical displacement meter 2a due to this bending is L 11 -L 21 and the displacement amount Δ2 of the detection probe of the horizontal displacement meter 2b is L 12 -L 22 The vertical inclination angle θ1, the horizontal inclination angle θ2, and the bending angle θ between the connected pipe bodies 4 and 5 can be calculated by the following equations (1) to (3). The measurement accuracy of the inclination angles θ1, θ2, and θ improves as the values of L1 and L2 increase.

[0039] (1) Equation: θ1 = tan -1 (Δ1 / L1) (2) Equation: θ2 = tan -1 (Δ2 / L2) (3) Equation: θ = cos -1 (cosθ1 × cosθ2)

[0040] According to this configuration, since the common displacement meters 2 (2a, 2b) and targets 3 (3a, 3b) can be used regardless of the nominal diameters of the pipe bodies 4 and 5, in-pipe inspection can be performed smoothly and the inspection cost can be reduced. Also, even for large-diameter pipe bodies 4 and 5 or seismic joints with joint expansion / contraction allowances, they can be dealt with using relatively small displacement meters 2. Further, even when the bending angle is large in large-diameter pipe bodies 4 and 5, the tip of the detection probe is less likely to deviate from the target 3, and in-pipe inspection can be performed smoothly.

[0041] A second embodiment of the in-pipe inspection device 1 according to the present invention is shown in FIGS. 3(a) and 3(b). The basic configuration of this in-pipe inspection device 1 has many parts in common with that of the first embodiment. However, it measures displacements in the same direction as the vertical displacement gauge 2a (one displacement gauge), and there is a parallel vertical displacement gauge 2a' (one parallel displacement gauge) provided side by side in the pipe axis direction with this vertical displacement gauge 2a, and it measures displacements in the same direction as the horizontal displacement gauge 2b (the other displacement gauge), and there is a parallel horizontal displacement gauge 2b' (the other parallel displacement gauge) provided side by side in the pipe axis direction with this horizontal displacement gauge 2b. Further, each displacement gauge 2 (2a, 2a', 2b, 2b') is attached by an attachment jig 6 fixed to the tip of the insertion port of the insertion-side pipe body 5. It is different in that each target 3 (3a, 3b) is provided on the inner surface of the receiving port of the receiving-side pipe body 4. Note that the description of the members common to the first embodiment is omitted.

[0042] In this configuration, the vertical target 3a abuts against the tips of the detection probes of both the vertical displacement gauge 2a and the parallel vertical displacement gauge 2a', and the horizontal target 3b abuts against the tips of the detection probes of both the horizontal displacement gauge 2b and the parallel horizontal displacement gauge 2b'.

[0043] When the in-pipe inspection device 1 is inserted into the existing pipe P, FIGS. 4(a) and 4(b) show the state in which the pipe bodies 4 and 5 are bent. Let the axial distance in the pipe axis direction of the tips of the detection probes of the vertical displacement gauge 2a and the parallel vertical displacement gauge 2a' in the state where the pipe bodies 4 and 5 are straight (see FIGS. 3(a) and 3(b)) be L1', and the axial distance in the pipe axis direction of the tips of the detection probes of the horizontal displacement gauge 2b and the parallel horizontal displacement gauge 2b' be L2'. Let the displacement difference between the vertical displacement gauge 2a and the parallel vertical displacement gauge 2a' in the state where the pipe bodies 4 and 5 are bent be δ1, and the displacement difference between the horizontal displacement gauge 2b and the parallel horizontal displacement gauge 2b' be δ2. At this time, the inclination angle θ1' in the vertical direction, the inclination angle θ2' in the horizontal direction, and the bending angle θ' between the connected pipe bodies 4 and 5 due to this bending can be calculated by the following equations (4) to (6). The measurement accuracy of the inclination angles θ1', θ2' and θ' improves as the values of L1' and L2' increase.

[0044] (4) Equation: θ1' = tan-1 (δ1 / L1’) (Equation (5)): θ2’ = tan -1 (δ2 / L2’) (Equation (6)): θ’ = cos -1 (cosθ1’ × cosθ2’)

[0045] In the configuration according to the first embodiment, when a shear load acts between the two tubular bodies 4 and 5 and the axial centers of the two tubular bodies 4 and 5 are eccentric, even if the tubular bodies 4 and 5 are not buckled, the detection probe is displaced (Δ1, Δ2 in the above formula (1) or (2)), and it may be unclear whether this displacement is caused by buckling or eccentricity between the tubular bodies 4 and 5. On the other hand, when the vertically arranged displacement gauge 2a and the parallel vertically arranged displacement gauge 2a’, and the horizontally arranged displacement gauge 2b and the parallel horizontally arranged displacement gauge 2b’ are arranged side by side in the tube axis direction as in the configuration according to the second embodiment, the displacement caused by the eccentricity of the two tubular bodies 4 and 5 is canceled out, and only the change amount caused by buckling can be accurately measured.

[0046] A third embodiment of the in-pipe inspection device 1 according to the present invention is shown in FIGS. 5(a) and 5(b). The basic configuration of this in-pipe inspection device 1 has many common parts with that of the second embodiment, but is different in that the vertical displacement gauge 2a and the parallel vertically arranged displacement gauge 2a’ are provided on the receiving tubular body, while the target 3 is provided on the inserting tubular body 5 side. This target 3 has a square bar-shaped member standing vertically toward the receiving tubular body 4 from the center of a disc-shaped member having the same normal plane as the tube axis direction fixed to the tip of the insertion port. The tips of the detection probes of the vertical displacement gauge 2a and the parallel vertically arranged displacement gauge 2a’ abut on one surface of this square bar-shaped member, and the tips of the detection probes of the horizontal displacement gauge 2b and the parallel horizontally arranged displacement gauge 2b’ abut on the other surface adjacent to this one surface at an angle of 90 degrees.

[0047] Also in this configuration, similar to the configuration according to the second embodiment, as shown in FIGS. 6(a) and 6(b), the vertical inclination angle θ1’, the horizontal inclination angle θ2’, and the bending angle θ’ between the connected tubular bodies 4 and 5 when the two tubular bodies 4 and 5 are bent can be calculated by the above formulas (4) to (6).

[0048] A fourth embodiment of the in-pipe inspection apparatus 1 according to the present invention is shown in Fig. 7. The basic configuration of this in-pipe inspection apparatus 1 has many parts in common with that of the first embodiment, but the configurations of the displacement gauges 2 and the targets 3 are different.

[0049] In this embodiment, as shown in Fig. 8(a), on a disk-shaped mounting jig 6 fixed so as to have a normal line in a plane in the same direction as the pipe axis, which is fixed inside the insertion port of the insertion-side pipe body 5, three through-holes are formed corresponding to the apex positions A, B, and C of a triangle, and displacement gauges 2 (hereinafter, these displacement gauges 2 are referred to as pipe-axis displacement gauges 2c, 2d, and 2e) are respectively attached to the respective through-holes. The three pipe-axis displacement gauges 2c, 2d, and 2e are arranged such that their detection probes project and retract parallel to the pipe axis direction. The axis of the insertion-side pipe body 5 is located inside each side of the triangle formed by the three pipe-axis displacement gauges 2c, 2d, and 2e.

[0050] The target 3 is a disk-shaped member fixed to the receiving port of the receiving-side pipe body 4 so as to have a normal line in a plane in the same direction as the pipe axis. As shown in Fig. 8(b), the tip of each detection probe abuts against the target 3 corresponding to the positions of the respective displacement gauges 2c, 2d, and 2e. Through-holes for passing the traction member 11 are formed at the center of the mounting jig 6 where each displacement gauge 2c, 2d, and 2e is provided and at the center of the target 3.

[0051] Let the installation coordinates on the mounting jig 6 of each displacement gauge 2c, 2d, and 2e be A(0, 0, 0), B(X B , Y B , 0), C(X C , Y C , 0), and let the displacement amounts in the pipe axis direction measured by each displacement gauge 2c, 2d, and 2e be Z A , Z B , Z C . Then, the contact coordinates on the target 3 at the tip of the detection probe are A’(0, 0, Z A ), B’(X B , Y B , Z B ), C’(X C , Y C , Z C) can be expressed as such. At the three points of the installation coordinates A, B, and C, the attachment surfaces of the respective displacement gauges 2c, 2d, and 2e are defined, and at the three points of the contact coordinates A', B', and C', the contact surface of the target 3 is defined respectively.

[0052] Here, the normal vector n of the attachment jig 6 to which the three pipe axis displacement gauges 2c, 2d, and 2e are attached is Vector n = (0, 0, 1) and can be represented as such. Also, the normal vector d of the target 3 can be obtained by the cross product of the vector A'B' and the vector A'C' as shown below. Vector d = Vector A'B' × Vector A'C' =(X B -0, Y B -0, Z B -Z A ) × (X C -0, Y C -0, Z C -Z A ) =(X B , Y B , Z B -Z A ) × (X C , Y C , Z C -Z A ) =(Y B (Z C -Z A ) - (Z B -Z A )Y C , (Z B -Z A )X C -X B (Z C -Z A )、X B Y C -Y B X C )

[0053] The angle θ formed by the vector n and the vector d is the bending angle θ between the receiving side pipe body 4 and the inserting side pipe body 5, and this bending angle θ is cosθ = Vector n · Vector d ÷ (|Vector n| · |Vector d|) =(0, 0, 1)·(Y B (Z C -Z A )-(Z B -Z A )Y C 、(Z B -Z A )X C -X B (Z C -Z A )、X B Y C -Y B X C ) ÷[1×√{(Y B (Z C -Z A )-(Z B -Z A )Y C ) 2 +((Z B -Z A )X C -X B (Z C -Z A )) 2 +(X B Y C -Y B X C ) 2}] =(X B Y C -Y B X C )÷√{(Y B (Z C -Z A )-(Z B -Z A )Y C ) 2 +((Z B -Z A )X C -X B (Z C -Z A )) 2 +(X B Y C -Y B X C ) 2} satisfies the relational expression. By substituting the coordinates of each of the above points A, B, C, A', B', and C' into this relational expression, the bending angle θ can be derived.

[0054] In the configuration where the pipe axis displacement gauges 2c, 2d, and 2e are provided at positions corresponding to the respective vertices of the triangle as described above, as shown in FIGS. 9(a) and 9(b), this triangle can be a right isosceles triangle. In this case, if the length of the equal sides of the right isosceles triangle is X B , then the installation coordinates on the mounting jig 6 of each displacement gauge 2c, 2d, and 2e can be expressed as A(0, 0, 0), B(X B , 0, 0), C(0, X B , 0). And if the displacement amounts in the pipe axis direction measured by each displacement gauge 2c, 2d, and 2e are Z A , Z B , Z C , then the contact coordinates on the target 3 at the tip of the detection probe can be simply expressed as A'(0, 0, Z A ), B'(X B , 0, Z B ), C'(0, X B , Z C ). Also in this configuration, the axis of the insertion-side pipe body 5 is located inside each side of the right isosceles triangle formed by the three pipe axis displacement gauges 2c, 2d, and 2e.

[0055] Here, similar to the above, if the normal vector n of the mounting jig 6 to which the three pipe axis displacement gauges 2c, 2d, and 2e are attached is vector n = (0, 0, 1) is represented, the normal vector d of the target 3 can be obtained by the cross product of vector A'B' and vector A'C' as shown below. vector d = vector A'B' × vector A'C' = (X B - 0, 0 - 0, Z B - Z A ) × (0 - 0, X B - 0, Z C - Z A ) = (X B , 0, Z B - Z A ) × (0, X B , Z C - Z A ) =(0 · (Z C -Z A ) - (Z B -Z A )X B 、(Z B -Z A ) · 0 - X B (Z C -Z A )、X B 2 -0) =X B · (Z A -Z B 、Z A -Z C 、X B )

[0056] Here, vector d = X B · vector d’ vector d’ = (Z A -Z B 、Z A -Z C 、X B ) If we set it like this, the angle θ formed by vector n and vector d’ becomes the bending angle θ between the receiving-side tubular body 4 and the inserting-side tubular body 5, and this bending angle θ is, cosθ = vector n · vector d’ ÷ (|vector n| · |vector d’|) =(0, 0, 1) · (Z A -Z B 、Z A -Z C 、X B ) ÷ √{(Z A -Z B ) 2 +(Z A -Z C ) 2 +X B 2} =X B ÷ √{(Z A -Z B ) 2 +(Z A -Z C ) 2 +X B 2} As compared with the case where three pipe axis displacement gauges 2c, 2d, and 2e are arranged at each vertex of the general triangle described above, it can be expressed by a simpler mathematical formula.

[0057] Also, when the angle formed by vector A'B' and vector A'C' is θd, the magnitude of the normal vector d of the target 3 is |vector d| = |vector A'B'|·|vector A'C'|·sinθd and can be obtained thereby. In this embodiment, since three pipe axis displacement gauges 2c, 2d, and 2e are installed at the vertices of a right isosceles triangle, the angle θd is 90 degrees. However, in reality, due to the error in the installation position, the value of the angle θd may deviate slightly from 90 degrees.

[0058] The influence on the magnitude of vector d when an error occurs in this angle θd can be evaluated by the change amount of sinθd with respect to a minute change in the angle θd, that is, cosθd which is the differential value of sinθd. When the angle θd is 90 degrees, cosθd = 0 and it becomes the minimum value. That is, even if an error occurs in the angle θd formed by vector A'B' and vector A'C' due to the error in the installation position of the displacement gauge, the influence on the calculation result of sinθd can be minimized. For the verification, when three pipe axis displacement gauges 2c, 2d, and 2e are installed at the vertices of a right isosceles triangle as in this embodiment and when installed at the vertices of an equilateral triangle, the sine values were calculated when an error of 5 degrees occurred in the value of the angle θd (the angle formed by vector A'B' and vector A'C' became 85 degrees). The calculation results are shown in Table 1.

[0059]

Table 1

[0060] In this way, by arranging the three pipe axis displacement gauges 2c, 2d, and 2e at the vertices of a right isosceles triangle, the influence of the installation accuracy error of these pipe axis displacement gauges 2c, 2d, and 2e on the calculation accuracy of the bending angle θ of both pipe bodies 4 and 5 can be minimized. Further, since the axis of the inserted pipe body 5 is located inside each side of the right isosceles triangle formed by the three pipe axis displacement gauges 2c, 2d, and 2e, the bending angle θ of the surface including the target 3 inclined with respect to the axis can be detected with higher accuracy.

[0061] A fifth embodiment of the in-pipe inspection device 1 according to the present invention is shown in FIG. 10. Although the basic configuration of this in-pipe inspection device 1 has many common parts with that of the fourth embodiment, the attachment jigs 6 for the pipe axis displacement gauges 2c, 2d, and 2e and the configuration of the target 3 are different.

[0062] In this embodiment, both the target 3 and the attachment jig 6 have a cylindrical member extending parallel to the pipe axis direction and a pair of flanges extending radially outward from both ends of this cylindrical member. The plate surfaces of these flanges each have a surface normal in the same direction as the pipe axis. The outer peripheral edges of these flanges are fixed to the inner peripheral surface of the receiving pipe body 4 or the inserted pipe body 5.

[0063] On the pair of flanges of the attachment jig 6, similar to those shown in FIG. 8(a) or FIG. 9(a), three (a total of six) through holes are formed corresponding to the vertex positions A, B, and C of a triangle (right isosceles triangle), respectively. The in-plane positions of the through holes formed in each flange coincide. When the pipe axis displacement gauges 2c, 2d, and 2e are inserted into the through holes formed in the pair of flanges, these pipe axis displacement gauges 2c, 2d, and 2e can be easily held in a state parallel to the axis. In this way, when the target 3 and the attachment jig 6 are configured, the perpendicularity of the target 3 and the attachment jig 6 with respect to the axis, and the parallelism of the pipe axis displacement gauges 2c, 2d, and 2e held by the attachment jig 6 with respect to the axis can be easily and surely achieved, and the inspection accuracy can be improved.

[0064] In each of the above-described embodiments, the data logger 7 provided in the tubular bodies 4 and 5 is configured to obtain data related to the insertion amount of the in-pipe inspection device 1. However, a distance meter may be installed in the traction member 11 that pulls the in-pipe inspection device 1, and a data logger different from the data logger 7 installed in the tubular bodies 4 and 5 may be configured to record the pulling distance and the measurement time of the in-pipe inspection device 1. By doing so, the position and the bending angle of the in-pipe inspection device 1 can be associated by associating the time of the built-in clock of the data logger 7 provided in the tubular bodies 4 and 5 with the time of the other data logger, or by considering the deviation between the times of both if there is a deviation between the times of both.

[0065] Alternatively, instead of configuring the data logger 7 to obtain data related to the insertion amount of the in-pipe inspection device 1, marks may be made at regular intervals (for example, every 10 meters) on the traction member 11 that pulls the in-pipe inspection device 1 with tape or the like, and the time for each fixed winding distance (for each insertion distance of the in-pipe inspection device 1) may be noted, or the traction member 11 may be video-recorded to record the insertion amount. By doing so, the time when the in-pipe inspection device 1 passes through each section of the existing pipe P becomes clear, and the maximum bending angle for each section can be estimated by associating that time with the time of the built-in clock of the data logger 7.

[0066] Also, assuming that the pulling speed of the in-pipe inspection device 1 by the traction member 11 is constant, the relationship between the insertion distance and the bending angle can be estimated by proportional calculation from the time change of the bending angle with respect to the total pulling time.

[0067] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. Therefore, the scope of the present invention is shown not by the above description but by the claims, and it is intended that all meanings equivalent to the claims and all modifications are included.

Explanation of Reference Numerals

[0068] 1 In-pipe inspection device 2 Displacement meter 2a Vertical displacement meter (one displacement meter) 2a’ Auxiliary vertical displacement gauge (one of the parallel displacement gauges) 2b Horizontal displacement gauge (other displacement gauge) 2b’ Auxiliary horizontal displacement gauge (other parallel displacement gauge) 2c, 2d, 2e Pipe axis displacement gauges 3 Target 3a Vertical target 3b Horizontal target 4 Receiving side pipe body (pipe body) 5 Inserting side pipe body (pipe body) 6 Mounting jig 7 Data logger 8 Tip member 9 Rotation sensor 10 Locking member 11 Tension member 12 Wire 13 Retractable distance meter P Existing pipe

Claims

1. A plurality of displacement gauges (2) fixed to one of the connected pipe bodies (4, 5) inserted inside the existing pipe (P), a target (3) fixed to the other pipe body (4, 5) of the connected pipe bodies (4, 5) and contacted by the detection probe of each displacement gauge (2), and having, calculating a bending angle θ between the connected pipe bodies (4, 5) from the displacement amount of each displacement gauge (2), the plurality of displacement gauges (2) being three displacement gauges (2c, 2d, 2e) provided so as to measure displacements in the pipe axis direction at positions corresponding to the vertices of a right isosceles triangle in a plane having the same plane normal as the pipe axis direction of the one pipe body (4, 5), the target (3) being fixed so as to have the same plane normal as the pipe axis of the other pipe body (4, 5), The lengths X of the two equal sides of the right-angled isosceles triangle Ｂ and the displacement amounts Z in the pipe axis direction measured by the three displacement gauges (2c, 2d, 2e) Ａ , Z Ｂ , Z Ｃ From these, the three-dimensional surface normal vector d of the surface including the target (3) is calculated by the following formula (7), and from this surface normal vector d and the three-dimensional surface normal vector n = (0, 0, 1) of the surface including the right-angled isosceles triangle, the cosine of the bending angle θ between the connected pipe bodies (4, 5) is calculated by the following formula (8). An in-pipe inspection device Equation (7): Vector d = X Ｂ · (Z Ａ − Z Ｂ , Z Ａ − Z Ｃ , X Ｂ ) Equation (8): cosθ = X Ｂ ÷√{(Z Ａ −Z Ｂ ) ２ +(Z Ａ −Z Ｃ ) ２ +X Ｂ ２}

2. The in-pipe inspection device according to claim 1, wherein the axis of the one pipe body (4, 5) is located inside each side of the right isosceles triangle formed by the three displacement gauges (2c, 2d, 2e).

3. The in-pipe inspection device according to claim 1 or 2, further comprising a data processing unit that measures the insertion amount of the connected pipe bodies (4, 5) into the existing pipe (P) and derives the relationship between the insertion amount and the bending angle θ.

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