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 internal pipe inspection device that performs a preliminary inspection as to whether or not a new pipe can be inserted into a sheath pipe of an existing pipe by a pipe-in-pipe construction method, prior to the installation of a fluid transport pipe for water or the like. [Background technology]

[0002] In the pipe-in-pipe method, in which a new ductile iron pipe (PN type pipe, PII type pipe, etc.) is inserted into an existing pipe (sheath pipe) to construct a new pipeline inside an deteriorated existing pipe, a preliminary survey is sometimes conducted before the actual construction to check whether the new pipe can be inserted smoothly.One of the preliminary survey methods is to join two mock pipes that simulate the new pipes to be actually inserted, and pull the joined mock pipes into the existing pipe with a wire pulled by a winch to check whether the mock pipes can pass smoothly from the starting shaft to the arrival shaft.

[0003] In the above preliminary investigation method, although it is possible to determine whether the jointed mock pipe can pass through, it is not possible to grasp the bending angle of the existing pipe in detail. The thrust is transmitted to the jointed pipe body via the lock ring, but the allowable thrust is determined by the bending angle of the new pipe, and if the bending angle is large, excessive thrust cannot be applied. For this reason, if the bending angle cannot be grasped in detail, it is necessary to use reinforced pipes such as pipes with welded rings or pipes with flanges and ribs to withstand the specified thrust required to propel the pipe body, which may be costly for safety reasons.

[0004] In order to investigate the bending angle inside an 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 that are passed through a pipeline 4 are connected by a universal joint 7. This universal joint 7 has rotational position detectors 8a, 8b, which detect the bending angle and direction of the cylindrical case 1 relative to the cylindrical case 2 (see Figure 2 of Patent Document 1, etc.).

[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 an 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 adjacent to each of the universal joints 7 and 8, and the bending angle in three-dimensional directions at the joint 2 of the existing pipe 1 can be obtained from data from these bending angle measuring devices and the like (see Figure 1 of Patent Document 2, etc.). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Utility Model Application Publication No. 2-118808 [Patent Document 2] Publication No. 3-18885 Summary of the Invention [Problem to be solved by the invention]

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

[0008] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to simply and accurately detect the bending angle between pipes when a connected pipe is passed through an existing pipe. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides: A plurality of displacement meters fixed to one of the connected pipes to be inserted into the inside of the existing pipe; a target fixed to the other of the connected pipes and against which a detection probe of each of the displacement meters abuts; The present invention provides an inside pipe inspection device that calculates the bending angle between the connected pipe bodies from the displacement amount of each of the displacement gauges.

[0010] In this way, the bending angle between the connected pipes can be easily and accurately detected, so that an appropriate pipe corresponding to that bending angle can be selected, thereby preventing excessive costs.

[0011] In the above configuration, One of the plurality of displacement gauges may be configured to measure displacement in a direction inclined with respect to the axial direction of the one of the tube bodies, and another of the plurality of displacement gauges may be configured to measure displacement in a direction inclined with respect to both the axial direction of the one of the tube bodies and the displacement measurement direction of the one displacement gauge.

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

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

[0014] In this way, the amount of displacement detected by each displacement meter can be applied to each equation, allowing the bending angle to be calculated smoothly.

[0015] In the case where the displacement gauge is inclined, instead of the above, the one displacement meter is provided to measure a displacement in a direction perpendicular to a tube axis direction of the one tube body, and the other displacement meter is provided to measure a displacement in a direction perpendicular to both the tube axis direction of the one tube body and a displacement measurement direction of the one displacement meter, The device further includes a first parallel displacement gauge arranged in line with the first displacement gauge in the tube axis direction, the first displacement gauge measuring a displacement in the same direction as the first displacement gauge, and a second parallel displacement gauge arranged in line with the second displacement gauge in the tube axis direction, the second displacement gauge measuring a displacement in the same direction as the second displacement gauge, The distance in the tube axial direction between the tips of the detection probes of the first displacement meter and the first parallel-installed displacement meter is L1', the difference in displacement between the first displacement meter and the first parallel-installed displacement meter when the connected tube is bent from a straight state is δ1, the distance in the tube axial direction between the tips of the detection probes of the other displacement meter and the other parallel-installed displacement meter is L2', and the difference in displacement between the other displacement meter and the other parallel-installed displacement meter when the connected tube is bent from a straight state is δ2. The inclination angle θ1' in the detection direction by the first displacement meter, the inclination angle θ2' in the detection direction by the other displacement meter, and the composite angle θ' of the two inclination angles θ1' and θ2', which is the bending angle θ' between the connected tubes, can be calculated using the following equations (4) to (6). (4) Formula: θ1'=tan -1 (δ1 / L1') (5) Equation: θ2' = tan -1 (δ2 / L2') (6) Equation: θ' = cos -1 (cosθ1'×cosθ2')

[0016] In this way, the eccentricity between the receiving and inserting ports of the two connected pipes can be offset from the difference in displacement between the two displacement gauges arranged side by side in the pipe axial direction, thereby making it possible to detect the bending angle between the two pipes more accurately.

[0017] In the above configuration, At least one of the connected tubes may be provided with a rotation sensor for detecting rotation about the tube axis.

[0018] In this way, even if the connected pipe rotates (rolls) around its axis when it is inserted into the existing pipe, the direction of the bending angle (composite angle) can be accurately detected based on the amount of rotation detected by the rotation sensor.

[0019] In the above configuration, The plurality of displacement gauges are three displacement gauges provided to measure displacement in the tube axis direction at positions corresponding to each vertex of a right-angled isosceles triangle in a plane having the same surface normal as the tube axis direction of the one tube body, the target is fixed so as to have a surface normal in the same direction as the tube axis of the other tube body, The length of the two equal sides of the right isosceles triangle is X B and the displacement Z in the axial direction of the tube measured by the three displacement gauges. A , Z B , Z C From the above, a three-dimensional surface normal vector d of the surface including the target is calculated using the following equation (7), and the cosine of the bending angle θ between the connected pipes is calculated using the following equation (8) 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. (7) 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 including the target can be directly calculated from the displacements of the three displacement gauges. Moreover, by arranging the three displacement gauges at the vertices of a right-angled isosceles triangle, the coordinate values ​​of each vertex can be standardized, and the surface normal vector d of the surface including the target and the cosine of the connected bending angle θ can be calculated using a simple formula. Even if the installation positions of the displacement gauges are shifted from the specified positions and an error occurs in the angle between the vectors of the two sides sandwiching the right angle of the right-angled isosceles triangle, the effect of the error on the calculation result can be minimized.

[0021] In the configuration in which the three displacement gauges are arranged at the vertices of an isosceles right triangle, The axis of the one pipe may be located inside each side of an isosceles right triangle formed by the three displacement gauges.

[0022] In this way, the bending angle of the surface including the target that is inclined with respect to the axis can be detected with higher accuracy.

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

[0024] In this way, it becomes clear at what position and to what extent the existing pipe is bent, so that the work can proceed smoothly based on the bending data when the actual pipe body is inserted. Effect of the Invention

[0025] According to the present invention, since the inside of a pipe inspection device is configured as described above, it is possible to simply and accurately detect the bending angle between the pipes when the connected pipes are passed through an existing pipe. [Brief description of the drawings]

[0026] [Figure 1] 1A is a cross-sectional view taken along line bb in FIG. 1A, showing a state in which pipes are straight relative to each other in a first embodiment of the pipe interior investigation device according to the present invention; FIG. 1B is a cross-sectional view taken along line bb in FIG. [Diagram 2] 1A is a cross-sectional view taken along line bb in FIG. 1A, showing a state in which tubes are bent together in a first embodiment; FIG. 1B is a cross-sectional view taken along line bb in FIG. [Diagram 3] 1A is a cross-sectional view taken along line bb in FIG. 1A, showing a state in which pipes are straight in relation to each other in a second embodiment (main part) of the pipe interior investigation device according to the present invention; FIG. 1B is a cross-sectional view taken along line bb in FIG. [Figure 4] 1A and 1B are cross-sectional views showing a state in which tubes are bent together in a second embodiment, in which (a) is a cross-sectional view taken along line bb in (a); [Diagram 5] 1A is a cross-sectional view taken along line bb in FIG. 1A, showing a third embodiment (main part) of a pipe interior investigation device according to the present invention in which pipe bodies are in a straight state. FIG. 1B is a cross-sectional view taken along line bb in FIG. [Figure 6] 11A and 11B are cross-sectional views showing a state in which the tubes are bent together in a third embodiment, in which (a) is a cross-sectional view taken along line bb in (a); [Figure 7] FIG. 13 is a cross-sectional view seen from the front, showing a state in which pipe bodies are straight in a fourth embodiment of the pipe interior investigation device according to the present invention; [Figure 8] 13A and 13B show a state in which displacement meters are arranged at the vertices of a triangle in the fourth embodiment, in which FIG. 13A shows the installation positions (coordinates) of the displacement meters on the insertion port side, and FIG. 13B shows the contact positions (coordinates) of the detection probe with the target on the receiving port side. [Figure 9] 13A and 13B show a state in which displacement meters are arranged at the vertices of a right-angled isosceles triangle in the fourth embodiment, in which FIG. 13A shows the installation positions (coordinates) of the displacement meters on the insertion port side, and FIG. 13B shows the contact positions (coordinates) of the detection probe with the target on the receiving port side. [Figure 10] FIG. 13 is a cross-sectional view seen from the front, showing a state in which pipe bodies are straight in a fifth embodiment of the pipe interior investigation device according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] A first embodiment of the pipe interior investigation device 1 according to the present invention is shown in Fig. 1(a)(b). This pipe interior investigation device 1 is a device for conducting a preliminary investigation as to whether a new pipe can be inserted into an existing pipe P by a pipe-in-pipe method prior to the laying of a fluid transport pipe such as a water supply pipe, and has a plurality of displacement meters 2 fixed to one of the connected pipes to be inserted into the inside of the existing pipe P, and a target 3 fixed to the other of the connected pipes, against which the detection probes of the displacement meters 2 abut. Fig. 1(a)(b) shows a state in which the pipes are straight. In this embodiment, one pipe is the receiving pipe 4 and the other pipe is the inserting pipe 5, but one pipe may be the inserting pipe 5 and the other pipe may be the receiving pipe 4.

[0028] The displacement meter 2 has a main body and a rod-shaped detection probe that protrudes from the main body. The detection probe is biased in one direction along its length (towards the target 3) by a biasing member (not shown). The detection probe is pushed into the main body against the biasing force of the biasing member, and the amount of displacement of the target 3 abutting against the tip of the detection probe is detected from the amount of pushing. An attachment jig 6 is provided on the main body, and the displacement meter 2 is attached to the inner surface of the socket of the receiving pipe 4 or near the inner surface of the socket by this attachment jig 6.

[0029] In this embodiment, mounting jigs 6 are fixed to two locations: the pipe bottom on the inner surface of the receiving port, and a position approximately 90 degrees circumferentially from the pipe bottom. One displacement meter 2 (hereinafter referred to as vertical displacement meter 2a) attached to the mounting jig 6 fixed to the pipe bottom has its detection probe protruding in the vertical direction, and the other displacement meter 2 (hereinafter referred to as horizontal displacement meter 2b) attached by the mounting jig 6 fixed at a position approximately 90 degrees circumferentially from the pipe bottom is arranged so that its detection probe protruding in the horizontal direction.

[0030] For example, a magnetic stand with an arm that can be attached to and detached from the inner surface of the pipe by magnetic force can be used as the mounting jig 6. By changing the fixing position of the displacement meter 2 to this arm, the displacement meter 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-like member that is L-shaped in a side view and has a portion extending toward the center of the tube axis and a portion extending from the end of the tube axis center side along the tube axis direction, which is provided near the tip of the insertion port of the insertion-side tube body 5. This target 3 is fixed to the tube top at the tip of the insertion port and at a position 90 degrees circumferentially from the tube top (a position approximately 180 degrees symmetrical to the fixed position of the mounting jig). The target 3a fixed to the tube top (hereinafter referred to as the vertical target 3a) has a portion extending along the tube axis direction abutting the tip of the detection probe of the vertical displacement meter 2a. Furthermore, the target 3b (hereinafter referred to as the horizontal target 3b) fixed at a position 90 degrees circumferentially from the tube top has a portion extending along the tube axis direction abutting 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.

[0032] By arranging the displacement meters 2 (2a, 2b) and the targets 3 (3a, 3b) in this way, the amount of vertical displacement caused by the bending of both tubes 4, 5 can be detected from the amount of depression of the detection probe of the vertical displacement meter 2a, and the amount of horizontal displacement caused by the bending of both tubes 4, 5 can be detected from the amount of depression of the detection probe of the horizontal displacement meter 2b. Data on the amount of displacement detected by each of the displacement meters 2a, 2b is stored in a data logger 7 provided inside the tubes 4, 5.

[0033] A tip member 8, which is a short length obtained by cutting a straight pipe section of a pipe having the same shape as the receiving side pipe 4, is connected to the front end of the receiving side pipe 4, which is the front side in the traveling direction of the pipe interior investigation device 1. This tip member 8 functions as a spacer to prevent the insertion side of the receiving side pipe 4 from tilting downward due to its own weight, and also functions as a friction reducing member (warping) to reduce friction between the insertion side and the inner surface of the existing pipe P.

[0034] A rotation sensor 9 is provided at the top of the receiving pipe 4 to detect the amount of rotation (amount of rolling) around the pipe axis of the connected pipes 4, 5. Even if rolling occurs in the pipes 4, 5 when the pipe interior investigation device 1 is inserted, the amount of displacement detected by each displacement gauge 2 (2a, 2b) can be corrected based on the amount of rotation detected by this rotation sensor 9, making it possible to accurately grasp the bending angle and bending direction between the connected pipes 4, 5.

[0035] A locking member 10 is fixed to the socket of the insertion side pipe 5, and a pulling member 11 is provided on this locking member 10. By pulling this pulling member 11, the pipe investigation device 1 can be moved forward.

[0036] A reel-type distance meter 13 is provided inside the connected pipes 4, 5, which detects the distance traveled by the pipe interior investigation device 1 from the length of wire 12 that is let out. One end of the wire 12 of this reel-type distance meter 13 is fixed to the starting shaft (not shown) side, so that the wound wire 12 is let out as the pipe interior investigation device 1 moves toward the arrival shaft (not shown) side. Data on the amount of wire 12 that is let out is accumulated in a data logger 7.

[0037] This data logger 7 has a function as a data processing unit that derives the relationship between the insertion amount of the pipe inside investigation device 1 and the bending angle based on data on the payout amount of the wire 12, data on the amount of displacement detected by each displacement meter 2 (2a, 2b), and the amount of rotation detected by the rotation sensor 9. Based on 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 a normal pipe, a pipe with a welded ring, and a pipe with flanges and ribs. In the following, illustrations of the data logger 7, the rotation sensor 9, the towing member 11, and the retractable distance meter 13 will be omitted as appropriate.

[0038] 2(a) and (b) show the state in which the pipe bodies 4 and 5 are bent when the pipe inside investigation device 1 is inserted into the existing pipe P. In the state in which the pipe bodies 4 and 5 are straight (see Figs. 1(a) and (b)), the distance in the pipe axial direction from the pipe end of the insertion side pipe body 5 to the tip of the detection probe of the vertical displacement meter 2a is L1, and the protruding length of the detection probe of the vertical displacement meter 2a that abuts against the vertical target 3a is L2. 11 The protruding length of the detection probe of the horizontal displacement meter 2b that contacts the horizontal target 3b is L 12 The projection length of the detection probe of the vertical displacement meter 2a that contacts the vertical target 3a when the tubes 4 and 5 are bent relative to each other is L 21 The protruding length of the detection probe of the horizontal displacement meter 2b that contacts the horizontal target 3b is L 22 At this time, the displacement Δ1 of the detection probe of the vertical displacement meter 2a due to this bending is L 11 -L 21 , the displacement 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 pipes 4 and 5 can be calculated by the following formulas (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) Formula: θ1=tan -1 (Δ1 / L1) (2) Equation: θ2 = tan -1 (Δ2 / L2) (3) Equation: θ = cos -1 (cosθ1×cosθ2)

[0040] According to this configuration, the same displacement meter 2 (2a, 2b) and target 3 (3a, 3b) can be used regardless of the nominal diameter of the pipes 4, 5, so that the inside of the pipe can be smoothly inspected and the inspection costs can be reduced. Also, the relatively small displacement meter 2 can be used even for large-diameter pipes 4, 5 and earthquake-resistant joints with a joint expansion allowance. Also, even if the bending angle is large in the large-diameter pipes 4, 5, the tip of the detection probe is unlikely to come off the target 3, so the inside of the pipe can be inspected smoothly.

[0041] A second embodiment of the pipe interior investigation device 1 according to the present invention is shown in Figures 3(a) and (b). The basic configuration of this pipe interior investigation device 1 has much in common with that of the first embodiment, but it further comprises a parallel vertical displacement meter 2a' (one parallel displacement meter) arranged in parallel with the vertical displacement meter 2a in the pipe axis direction and measuring displacement in the same direction as the vertical displacement meter 2a (one displacement meter), and a parallel horizontal displacement meter 2b' (another parallel displacement meter) arranged in parallel with the horizontal displacement meter 2b in the pipe axis direction and measuring displacement in the same direction as the horizontal displacement meter 2b (another displacement meter), and each displacement meter 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. The second embodiment differs in that the second embodiment is attached to the receiving side pipe 4, and that the targets 3 (3a, 3b) are provided on the inner surface of the receiving mouth of the receiving side pipe 4. Note that a description of the members common to the first embodiment will be omitted.

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

[0043] Figures 4(a) and (b) show the state in which the pipe bodies 4 and 5 are bent when the pipe investigation device 1 is inserted into the existing pipe P. The distance in the pipe axis direction between the tips of the detection probes of the vertical displacement meter 2a and the parallel vertical displacement meter 2a' when the pipe bodies 4 and 5 are straight (see Figures 3(a) and (b)) is L1', the distance in the pipe axis direction between the tips of the detection probes of the horizontal displacement meter 2b and the parallel horizontal displacement meter 2b' is L2', and the difference in the displacement between the vertical displacement meter 2a and the parallel vertical displacement meter 2a' when the pipe bodies 4 and 5 are bent is δ1, and the difference in the displacement between the horizontal displacement meter 2b and the parallel horizontal displacement meter 2b' is δ2. At this time, the vertical inclination angle θ1', the horizontal inclination angle θ2', and the bending angle θ' between the connected pipe bodies 4 and 5 due to this bending can be calculated by the following formulas (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) Formula: θ1'=tan-1 (δ1 / L1') (5) Equation: θ2' = tan -1 (δ2 / L2') (6) Equation: θ' = cos -1 (cosθ1'×cosθ2')

[0045] In the configuration of the first embodiment, when a shear load acts between the two tubes 4, 5 and the axes of the two tubes 4, 5 become eccentric, the detection probe is displaced even if the tubes 4, 5 are not bent relative to each other (Δ1, Δ2 in the above formula (1) or (2)), and it may become unclear whether this displacement is due to the bending or eccentricity of the tubes 4, 5 relative to each other. In contrast, when the vertical displacement meter 2a and the parallel vertical displacement meter 2a', and the horizontal displacement meter 2b and the parallel horizontal displacement meter 2b' are arranged side by side in the tube axial direction, as in the configuration of the second embodiment, the displacements due to the eccentricity of the two tubes 4, 5 are offset, and only the amount of change due to the bending can be accurately measured.

[0046] A third embodiment of the pipe interior investigation device 1 according to the present invention is shown in Fig. 5(a)(b). The basic configuration of this pipe interior investigation device 1 has many parts in common with that of the second embodiment, but it differs in that the vertical displacement meter 2a and the juxtaposed vertical displacement meter 2a' are provided on the receiving side pipe, while the target 3 is provided on the insertion side pipe 5 side. This target 3 has a square rod-shaped member that is vertically erected toward the receiving side pipe 4 from the center of a disk-shaped member that has a surface normal that is the same as the pipe axis direction and is fixed to the tip of the insertion port. The tips of the detection probes of the vertical displacement meter 2a and the juxtaposed vertical displacement meter 2a' are in contact with one surface of this square rod-shaped member, and the tips of the detection probes of the horizontal displacement meter 2b and the juxtaposed horizontal displacement meter 2b' are in contact with the other surface adjacent to the first surface at an angle of 90 degrees.

[0047] In this configuration, as in the configuration of the second embodiment, the vertical inclination angle θ1', the horizontal inclination angle θ2', and the bending angle θ' between the connected tubes 4 and 5 when both tubes 4 and 5 are bent as shown in Figures 6(a) and (b) can be calculated using the above equations (4) to (6).

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

[0049] In this embodiment, as shown in Fig. 8(a), a disk-shaped mounting jig 6 is fixed to have a surface normal in the same direction as the tube axis fixed inside the insertion port of the insertion side tube body 5, and three through holes are formed corresponding to the vertices A, B, and C of a triangle, and a displacement meter 2 (hereinafter, these displacement meter 2 are referred to as tube axis displacement meter 2c, 2d, and 2e) is attached to each through hole. The three tube axis displacement meter 2c, 2d, and 2e are arranged so that their detection probes protrude and retract parallel to the tube axis direction. The axis of the insertion side tube body 5 is located inside each side of the triangle formed by the three tube axis displacement meter 2c, 2d, and 2e.

[0050] The target 3 is a disk-shaped member fixed to the socket of the receiving tube 4 so as to have a surface normal in the same direction as the tube axis. As shown in Fig. 8(b), the tip of each detection probe abuts against the target 3 in correspondence with the position of each displacement gauge 2c, 2d, 2e. A through hole for passing the traction member 11 is formed in the center of the mounting jig 6 on which each displacement gauge 2c, 2d, 2e is provided, and in the center of the target 3.

[0051] The installation coordinates of each of the displacement gauges 2c, 2d, and 2e on the mounting jig 6 are A(0,0,0), B(X B , Y B , 0), C(X C , Y C , 0), and the displacement in the tube axis direction measured by each displacement gauge 2c, 2d, and 2e is Z A , Z B , Z C Then, the contact coordinates of the tip of the detection probe on the target 3 are A'(0, 0, Z A ), B'(X B , Y B , Z B ), C'(X C , Y C , Z CThe mounting surfaces of the displacement gauges 2c, 2d, and 2e are defined by the three points of the installation coordinates A, B, and C, and the contact surface of the target 3 is defined by the three points of the contact coordinates A', B', and C'.

[0052] Here, the normal vector n of the mounting jig 6 to which the three tube axis displacement gauges 2c, 2d, and 2e are attached is Vector n=(0, 0, 1) In addition, the normal vector d of the target 3 can be calculated as the cross product of vector A'B' and vector A'C' as shown below. Vector d = Vector A'B' x 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 between the vector n and the vector d is the bending angle θ between the receiving side tube 4 and the inserting side tube 5. 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} The following relational expression is satisfied. By substituting the coordinates 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 above-mentioned configuration in which the tube axis displacement gauges 2c, 2d, and 2e are provided at positions corresponding to the vertices of a triangle, the triangle can be an isosceles right triangle, as shown in Fig. 9(a) and (b). In this case, the length of the equal side of the isosceles right triangle is X. B Then, the installation coordinates of each of the displacement gauges 2c, 2d, and 2e on the mounting jig 6 are A(0,0,0), B(X B , 0, 0), C(0, X B , 0), and the tube axis measured by each displacement gauge 2c, 2d, and 2e Displacement in the Z direction A , Z B , Z C Then, the contact coordinates of the tip of the detection probe on the target 3 are A'(0, 0, Z A ), B'(X B , 0, Z B ), C'(0, X B , Z C In this configuration, the axis of the insertion-side tube body 5 is also located inside each side of the right-angled isosceles triangle formed by the three tube axis displacement gauges 2c, 2d, and 2e.

[0055] Here, as in the above, the normal vector n of the mounting jig 6 to which the three tube axis displacement gauges 2c, 2d, and 2e are attached is Vector n=(0, 0, 1) Then, the normal vector d of the target 3 can be calculated as the cross product of vector A'B' and vector A'C' as shown below. Vector d = Vector A'B' x 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] Where: Vector d=X B Vector d' Vector d'=(Z A -Z B , Z A -Z C , X B ) Then, the angle θ between the vector n and the vector d' is the bending angle θ between the receiving side tube 4 and the inserting side tube 5. This bending angle θ is expressed as follows: 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} This can be expressed by a simpler formula than the case where three tube axis displacement gauges 2c, 2d, and 2e are arranged at the vertices of the general triangle described above.

[0057] In addition, the magnitude of the normal vector d of the target 3 is given by θd, where θd is the angle between vector A'B' and vector A'C'. |vector d|=|vector A'B'|·|vector A'C'|·sinθd In this embodiment, the angle θd is 90 degrees because the three tube axis displacement meters 2c, 2d, and 2e are installed at the vertices of an isosceles right triangle, but in reality, the value of the angle θd may deviate slightly from 90 degrees due to an error in the installation position.

[0058] The effect on the magnitude of vector d when an error occurs in this angle θd can be evaluated by the amount of change in sinθd with respect to a small change in the angle θd, that is, cosθd, which is the differential value of sinθd. When the angle θd is 90 degrees, cosθd=0, which is the minimum value. In other words, even if an error occurs in the angle θd between vectors A'B' and A'C' due to an error in the installation position of the displacement gauge, the effect on the calculation result of sinθd can be minimized. To verify this, the sine value was calculated when an error of 5 degrees occurs in the value of angle θd (the angle between vectors A'B' and A'C' becomes 85 degrees) when the three tube axis displacement gauges 2c, 2d, and 2e are installed at the vertices of a right-angled isosceles triangle as in this embodiment and when they are installed at the vertices of an equilateral triangle. The calculation results are shown in Table 1.

[0059] [Table 1]

[0060] In this way, by arranging the three tube axis displacement gauges 2c, 2d, 2e at the vertices of a right-angled isosceles triangle, it is possible to minimize the effect that errors in the installation accuracy of the tube axis displacement gauges 2c, 2d, 2e have on the calculation accuracy of the bending angle θ of both tube bodies 4, 5. In addition, since the axis of the insertion side tube body 5 is located inside each side of the right-angled isosceles triangle formed by the three tube axis displacement gauges 2c, 2d, 2e, it is possible to detect with high accuracy the bending angle θ of the plane including the target 3 that is inclined with respect to the axis.

[0061] A fifth embodiment of the pipe interior investigation device 1 according to the present invention is shown in Fig. 10. The basic configuration of this pipe interior investigation device 1 has many parts in common with the fourth embodiment, but the configurations of the mounting jig 6 for the pipe axis displacement meters 2c, 2d, and 2e and the target 3 are different.

[0062] In this embodiment, the target 3 and the mounting jig 6 each have a cylindrical member extending parallel to the tube axis direction, and a pair of flanges extending radially outward from both ends of the cylindrical member. The plate surfaces of the flanges each have a surface normal in the same direction as the tube axis. The outer peripheral edge of the flange is fixed to the inner peripheral surface of the receiving tube 4 or the inserting tube 5.

[0063] In the pair of flanges of the mounting jig 6, three through holes (six in total) are formed corresponding to the vertices A, B, and C of a triangle (isosceles right triangle) as shown in FIG. 8(a) or FIG. 9(a). The in-plane positions of the through holes formed in each flange are the same, and when the tube axis displacement gauges 2c, 2d, and 2e are inserted into the through holes formed in the pair of flanges, the tube axis displacement gauges 2c, 2d, and 2e can be easily held parallel to the axis. By configuring the target 3 and the mounting jig 6 in this way, the perpendicularity of the target 3 and the mounting jig 6 to the axis and the parallelism of the tube axis displacement gauges 2c, 2d, and 2e held by the mounting jig 6 to the axis can be easily and reliably achieved, thereby improving the inspection accuracy.

[0064] In each of the above embodiments, data relating to the insertion amount of the inside pipe investigation device 1 is obtained by the data logger 7 installed in the pipes 4 and 5, but it is also possible to install a distance meter on the towing member 11 that tows the inside pipe investigation device 1, and to have a data logger separate from the data logger 7 installed in the pipes 4 and 5 record the retraction distance of the inside pipe investigation device 1 and the measurement time. In this way, the position of the inside pipe investigation device 1 can be associated with the bending angle by matching the time of the built-in clock of the data logger 7 installed in the pipes 4 and 5 with that of the separate data logger, or by taking into account any discrepancy between the times of the two.

[0065] Also, instead of using the data logger 7 to obtain data related to the insertion amount of the inside pipe investigation device 1, it is also possible to mark the towing member 11 that tows the inside pipe investigation device 1 with tape or the like at regular intervals (for example, 10 meters) and record the insertion amount by making a note of the time for each fixed winding distance (each insertion distance of the inside pipe investigation device 1) or by videotaping the towing member 11. In this way, the time when the inside pipe investigation device 1 passes through each section of the existing pipe P becomes clear, and by correlating this time with the time on the built-in clock of the data logger 7, the maximum bending angle for each section can be estimated.

[0066] In addition, assuming that the pulling speed of the pipe investigation device 1 by the pulling member 11 is constant, the relationship between the insertion distance and the bending angle can be estimated by proportional calculation from the change in the bending angle over time relative to the total pulling time.

[0067] The embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. Therefore, the scope of the present invention is defined by the claims, not by the above description, and is intended to include the meaning equivalent to the claims and all modifications. [Explanation of symbols]

[0068] 1. Pipe investigation device 2 Displacement gauge 2a Vertical displacement meter (one displacement meter) 2a' Parallel vertical displacement meter (one parallel displacement meter) 2b Horizontal displacement meter (other displacement meter) 2b' Parallel horizontal displacement meter (other parallel displacement meter) 2c, 2d, 2e Tube Axis Displacement Meter 3. Target 3a Vertical Target 3b Horizontal Target 4 Receiving tube (tube) 5 Insertion side tube (tube) 6 Mounting jig 7 Data Logger 8 Tip member 9 Rotation Sensor 10 Locking member 11 Traction member 12 Wire 13 Retractable rangefinder P Existing pipe

Claims

1. A plurality of displacement gauges (2) fixed to one of the connected pipes (4, 5) to be inserted into the existing pipe (P); a target (3) fixed to the other of the connected pipes (4, 5) and against which a detection probe of each of the displacement meters (2) abuts; Calculating a bending angle θ between the connected pipes (4, 5) from the displacement of each of the displacement gauges (2); The plurality of displacement gauges (2) are three displacement gauges (2c, 2d, 2e) provided to measure displacement in the tube axis direction at positions corresponding to each vertex of a right-angled isosceles triangle in a plane having the same surface normal as the tube axis direction of one of the tube bodies (4, 5), The target (3) is fixed so as to have a surface normal in the same direction as the tube axis of the other tube body (4, 5); The length of the two equal sides of the right isosceles triangle is X Ｂ and the displacement amount Z in the tube axis direction measured by the three displacement gauges (2c, 2d, 2e). Ａ , Z Ｂ , Z Ｃ The pipe investigation device calculates a three-dimensional surface normal vector d of the surface including the target (3) using the following equation (7), and calculates the cosine of the bending angle θ between the connected pipe bodies (4, 5) using the following equation (8) 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. (7) Equation: 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. 2. The pipe interior investigation device according to claim 1, wherein the axis of one of the pipes (4, 5) is located inside each side of a right-angled isosceles triangle formed by the three displacement gauges (2c, 2d, 2e).

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

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