APPARATUS FOR INSPECTING PIPELINE

Abstract: A system for inspecting whether or not a pipeline (18) is eccentric comprises the steps of directing a beam (20) from one end of the pipeline to the other end, disposing detecting means (24,158), which is provided with a light receiving body (50,50′) having a light receiving surface (56,56′) for receiving the beam and a television camera (60,60′) for taking a picture of the light receiving body, in the pipeline to be moved axially of the pipeline, processing an output signal of the television camera while maintaining the position of the light receiving body to have a predetermined relationship to the inner surface of the pipeline and inspecting whether or not the pipeline is eccentric on the basis of the result of processing.

Description: This invention relates to an apparatus for inspecting a pipeline by utilizing a beam directed from one end of a pipeline to the other to inspect whether or not said pipeline is eccentric, comprising: detecting means disposed in said pipeline to be movable along the axis of said pipeline and provided with a tubular casing disposed to extend in a direction along the axis of said pipeline, a light receiving body having a light receiving surface for receiving said beam, a maintaining mechanism for maintaining releasably a position of said light receiving body relative to said inner surface such that the light receiving body has a predetermined positional relationship to the inner surface of said pipeline, said light receiving body and said maintaining mechanism being supported by said casing and means for processing a signal to inspect whether or not said pipeline is eccentric. An existing pipeline or newly laid pipeline needs to be inspected in a plurality of longitudinal portions as to whether or not the pipeline is eccentric. This inspective operation can be carried out by an ordinary leveling method if the pipeline to be inspected is a large bore pipeline, of which an operator can enter. In the case of a small bore pipeline such as a sewer pipe, however, the inspective operation as noted above cannot be carried out this way because the operator cannot enter such a small bore pipeline. From EP-A-0 029 881 a drawing device is known for measuring the bending of the inner wall of a pipe. The drawing device is provided with a casing, said casing being centrically arranged within the interior of the pipe. The casing comprises a measuring means and is slidably arranged in the longitudinal direction. The measuring means, comprising a photodiode, is freely pivotable around the axis of the casing and is supported so that the axis of the measuring means will always find the same position parallel to the measuring plane, even if the casing rotates during advancement in the pipe. US-A-3 707 330 discloses a light beam guiding device for guiding tunneling machines. A light source is thereby mounted in a tunnel parallel to the desired direction of travel of the tunneling machine. Two target means are mounted at axially spaced locations along the light beam to the tunneling machine via support foots. A certain light pattern on the first illuminated target is projected onto the second illuminated target. From the location of the projected pattern on the second target, a bending of the pipe is indicated. An object of the present invention is to provide an apparatus with the features of the first part of claim 1 in which the ability for inspecting whether or not the pipeline is eccentric, is improved. According to the present invention, this object is achieved in a television camera for taking a picture of said light receiving body, said television camera being also supported by said casing and providing output signals for processing by said means and that said maintaining mechanism is provided with a plurality of members disposed around said casing and connected to said casing to be variable positions of said members on straight lines extending radially of said casing and a drive mechanism for changing the positions of said members on the straight lines extending radially of said casing. According to the present invention, since the detecting means is disposed at a predetermined position in the pipeline to inspect whether or not the pipeline is eccentric at the predetermined position on the basis of the output signal of the television camera, an operator can inspect whether or not the pipeline is eccentric without entering the interior of the pipeline. Also, according to the present invention, since the position of the light receiving body relative to the inner surface of the pipeline is maintained such that the inner surface has a predetermined positional relationship to the light receiving body when inspection is done, it is possible to accurately inspect whether or not the pipeline is eccentric. The foregoing and other objects and features of the invention will become apparent from the following description of a preferred embodiment of the invention with reference to the accompanying drawings, in which: Fig. 1 is a schematic view showing an embodiment of an inspection apparatus according to the present invention; Fig. 2 is a longitudinal sectional view showing an embodiment of a detecting device used in the inspection apparatus according to the present invention; Fig. 3 is a sectional view taken along the line 3-3 in Fig. 2; Fig. 4 is an end view taken along the line 4-4 in Fig. 2; Fig. 5 is a sectional view taken along the line 5-5 in Fig. 2; Fig. 6 is a view for explaining the positional relationship among an elongate member, a wheel and a pipeline when a maintaining mechanism is contracted; Fig. 7 is a front view showing the inspection apparatus having the detecting device shown in Fig. 2 and mounted on a carriage; Fig. 8 is a fragmentary sectional view showing a truck of the carriage; Fig. 9 is a sectional view taken along the line 9-9 in Fig. 8; Fig. 10 is a view for explaining the positional relationship between the carriage and a light receiving plate; Fig. 11 is a longitudinal sectional view showing another embodiment of a detecting section of the detecting device; Fig. 12 is a view showing a television camera and a frame of the detecting device shown in Fig. 11; Fig. 13 is a view showing the light receiving plate used in the detecting device shown in Fig. 11; Fig 14 is a view for explaining a method of calculating the inclination of a pipeline portion between positions to be measured; and Fig. 15 is a view for explaining a method of calculating a variation in the slant angle of the pipeline. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An inspection apparatus 10 shown in Fig. 1 is used for measuring eccentricities at a plurality of longitudinal spots of a pipeline 18 affording communication between two manholes 14, 16 constructed in the ground 12 to inspect whether or not the pipeline is eccentric on the basis of the measured value. The section of the pipeline 18 is circular. The inspection apparatus 10 comprises a beam generating device 22 for generating a beam 20 directed from the manhole 14 to the manhole 16 through the pipeline 18, a detecting device 24 disposed in the pipeline 18 and adapted for receiving the beam 20 to generate information corresponding to a light receiving position, a processing device 26 for processing an output signal of the detecting device and a well-known range finder 28 such as a light wave range finder for measuring a distance ℓ between the manhole 14 and the light receiving position. The beam generating device 22 is provided with a beam generator for generating a fine spot beam 20 such as a laser beam. The beam generating device 22 is also installed in the manhole 14 such that the beam 20 is directed from the center of a manhole 14-side end of the pipeline 18 to the center of a manhole 16-side end of the pipeline 18. In order to install the beam generating device 22 in such a manner, a circular slit may be provided respectively in the centers of two disks 30 and the respective disks 30 may be disposed at ends of the pipeline 18. Then, the beam generating device 22 may be fixed to a position which is selected such that the beam 20 passes through the slits of both disks 30. Both disks 30 are removed when the eccentricity is measured. Since the beam 20 is directed from the center of the manhole 14-side end of the pipeline 18 to the center of the manhole 16-side end thereof, the beam 20 is used for a reference line adapted for measuring the axial deviation of the pipeline 18. However, the beam to be used does not need to pass along the center axis of the pipeline 18, but may pass through positions spaced from the center axis of the pipeline 18 by a predetermined distance. As shown in Fig. 2, the detecting device 22 comprises a casing 32 provided with three sections, i.e., tubular bodies 34,36,38 connected in series to each other and aligned with each other. The tubular bodies 34,36 sandwiching a disk-like wall 40 therebetween are connected to each other by a plurality of bolts and the tubular bodies 36,38 are connected to each other by a plurality of bolts. A hole is bored in the central portion of the wall 40. The wall 40 has a shaft 42 extending along the axis of casing 32 and supported rotatably about the axis of the casing 32 while being supported coaxially with the casing 32. As shown in Figs. 2 and 3, the detecting device 24 also comprises a frame 44 disposed in the tubular body 36. The frame 44 has a plate-like portion 46 and a portion 48 having a U-shaped section and is fixed to the shaft 42 in the portion 46 such that the portion 46 extends in parallel to the wall 40 at the wall 40-side and the portion 48 extends from the wall 40 to the tubular body 38 in the tubular body 36. Thus, the frame 44 can be rotated about the axis of the casing 32. On an end of the portion 38 opposite to the portion 36, a circular light receiving body 50 is rotatably supported about the axis of the casing 32 within a plane orthogonal to the axis of the casing 32. The light receiving body 50 is provided with a ring 54 rotatably supported by a plurality of rollers 52 in the portion 38 and a disk-like light receiving plate 56 fixed to the ring 54 and made of a translucent material. As shown in Fig. 4, a latticed pattern is drawn on one surface of the light receiving plate 56. A hole 58 smaller than the spot of the beam 20 is bored in the center of the light receiving plate 56. The ring 54 and light receiving plate 56 are disposed in such manner that the center of the light receiving plate 56 always coincides with the axis of the casing 32 even if the light receiving body 50 is rotated angularly relative to the casing 32. On the portion 48 of the frame 44 is installed a television camera 60 for taking or picking up a picture of the back of the light receiving plate 56. The output signal of the television camera 60 is supplied to the processing device 26 installed on the ground. The frame receiving body 50 are interconnected by a connecting piece 62 without changing the mutual positional relationship between the light receiving surface of the light receiving plate 56 and the television camera 60. As shown in Figs. 2, 5 and 6, the detecting device 24 is also provided with a maintaining mechanism 64 for releasably fixing the light receiving body 50 and inner surface of the pipeline 18 so as to keep a predetermined positional relationship therebetween. The maintaining mechanism 64 is provided with a plurality (three in the example shown) of elongate members 66 pressed against the inner surface of the pipeline 18 such as to make the center of the light receiving plate 56 coincide with the axis of the pipeline 18. Each elongate member 66 extends along the axis of the casing 32 outside the casing and is connected to the casing 32 by a pair of parallel links 68 to be variable a position of the elongate member on a straight line extending radially of the casing 32. One of the pair of links 68 is connected to the casing 32 through a disk-like bed seat 70 fixed to the casing 32 at the side opposite to the light receiving body 50 and the other link 68 is connected directly to the casing 32. The elongate members 66 are disposed around the casing 32 at equal angular intervals. On each link 68 is mounted a wheel 72 and each elongate member 66 is formed with a hole 74 for allowing a portion of the wheel 72 to project outside the elongate member 66 when the elongate member approaches the casing 32. Further, a plurality of wheels 72 may be mounted on each elongate member 66. In this case, the elongate member can be shortened. Also, the maintaining mechanism 64 comprises a drive mechanism for pushing the elongate members 66 toward the inner surface of the pipeline 18. The drive mechanism is provided with a screw rod 76 rotatable around the axis of the casing 32, a drive source 78 for rotating the screw rod 76, a slider 80 engaging threadingly the screw rod 76 and a link 82 for interconnecting the slider 80 and elongate member 66 with each other. The screw rod 76 is supported by the wall 40 and bed seat 70 to be coaxial with the casing 32. The drive source 78 is provided with a rotational source such as a motor and a reduction gear connected to an output shaft thereof. The drive source 78 is mounted on the casing 32 through the bed seat 70 by a mounting base 86. The slider 80 is allowed to move axially of the casing 32 by a guide 84 fixed to the casing 32, but blocked from the rotation about the axis of the casing 32. Thus, the slider 80 is moved axially of the casing 32 by the rotation of the screw rod 76, so that the angle of the link 82 with respect to the axis of the casing 32 is varied. As a result, the position of the elongate member 66 is changed radially of the casing 32. The position of the slider 80 retreating toward the bed seat 70 is restricted by a stopper 87 mounted on the bed seat 70. Further, a slot 88 for the link 82 is bored in the tubular body 34 of the casing 32. Further, the drive mechanism may use a shaft, a piston-cylinder device and a slider supported movably axially of the shaft respectively, in place of the screw rod 76, drive source 78 and slider 80. In this case, the link 68 is connected to the slider and then slider is moved by the piston-cylinder device. The shaft 42, screw rod 76 and drive mechanism 78 are formed respectively in portions coincident with the axis of the casing 32 with holes 90,92,94 smaller than the spot of the beam 20 and penetrating in the axial direction of the casing 32. The processing device 26 is provided with a cathode ray tube, i.e., monitor, such as a television receiver for projecting or reproducing the image of the light receiving plate 56 on the basis of the output signal of the television camera 60, a processing circuit for calculating a distance, i.e., eccentricity between the center of the light receiving plate 56 and the portion of the light receiving plate irradiated by the beams 20 and the inclination ϑ of the beam 20 from the beam generating device 22 and a memory for storing the eccentricity together with a distance signal from the range finder 28. When inspection is done, distances L₁,L₂,L₃ shown in Fig. 1 are first measured. These measurements are carried out after theodolites 100,102 are disposed respectively above the manholes 14,16 to adjust the positions of both theodolites 100,102 such that a vertical beam 104 from the theodolite 100 is irradiated on a mark 106 premarked on the bottom of the manhole 14 after the vertical beam 104 crosses the beam 20 from the beam generating device 22 while a vertical beam 110 from the theodelite 102 is irradiated on a mark 112 premarked on the bottom of the manhole 16 after the vertical beam 110 crosses a horizontal beam 108 from the theodolite 100 and the beam 20 from the beam generating device 22. The measured distances L₁,L₂,L₃ are inputted to the processing device 26. In the processing device 26, distances are used for the following calculation; tan ϑ= (L₃-L₂) ÷ L₁ in order to obtain the inclination ϑ of the beam 20 from the beam generating device 22. The measured distances L₁,L₂,L₃ and obtained inclination ϑ are stored in the memory of processing device. After the measurements of the distances L₁,L₂,L₃ are done, the disk 30 is removed and a wire for moving the detecting device 24 along the pipeline 18 is mounted on the detecting device 24. Thus, the detecting device 24 is disposed in the pipeline 18 such that the light receiving body 50 is located at the beam generating device 22-side. When the detecting device 24 is disposed in the pipeline 18, the slider 80 is moved to the wall 40 by actuating the drive source 78 and then the elongate member 66 is pressed against the inner surface of the pipeline 18. Thus, since the axes of the casing 32 and light receiving plate 56 are aligned with the center of the pipeline 18, the beam 20 is irradiated on the center of the light receiving plate 56 and a partial beam 20′ of the beam 20 passes through the holes 58,90,92 and 94 and then reaches the manhole 16. When the partial beam 20′ reaches the manhole 16, it can be confirmed that the beam generating device 22 and detecting device 24 are correctly disposed. Next, the detecting device 24 is moved from the manhole 14 to the manhole 16 or vice versa after the slider 80 is moved to the bed seat 70. As shown in Fig. 2, since the slider 80 is moved to the bed seat 70 during the movement of the detecting device 24, the wheel 72 of the link 68 connected to the pair of elongate members 66 contacts the inner surface of the pipeline 18. Therefore, the detecting device 24 moves smoothly. The moving distance of the detecting device 24 is measured by the range finder 28 and the measured value is supplied to the processing device 26. When the detecting device 24 is moved by a predetermined distance, the detecting device 24 is stopped to carry out a process of measuring the eccentricity of the pipeline 18 in the stopping position. When the measuring process is done, the slider 80 is moved to the wall 40 by actuating the drive source 78 and then each elongate member 66 is pressed against the inner surface of the pipeline 18. Thus, the axes of the casing 32 and light receiving plate 56 are aligned with the center of the pipeline 18 in the stopping position of the detecting device 24, i.e., in the measuring position. When the pipeline 18 is not eccentric in the measuring position, the beam 20 is irradiated on the center of the light receiving plate 56, so that the center of the light receiving plate 56 has the light intensity higher than that of the other portions thereof. A part of the beam irradiated on the center of the light receiving plate 56 passes through the holes 58,90,92 and 94 and then reaches the manhole 16. Thus, when the partial beam 20′ reaches the manhole 16, it can be confirmed that the pipeline 18 is not eccentric at the stopping position of the detecting device. On the other hand, when the pipeline 18 is eccentric in the measuring position, the beam 20 is irradiated on a spot offset from the center of the light receiving plate 56, so that the irradiated portion has the light intensity higher than that of the other spots. Also, the beam 20 irradiated on the light receiving plate 56 does not pass through the holes 58,90,92 and 94. Thus, since the beam does not reach the manhole 16, it can be confirmed that the pipeline 18 is eccentric at the stopping position of the detecting device 24. The television camera 60 takes a picture of the light receiving plate 56 to transmit the output signal to the processing device 26. The monitor of the processing device 26 projects the image of the light receiving plate 56. When the pipeline 18 is not eccentric at the measuring position, the center of a display surface of the monitor has a high light intensity or hight brightness. On the other hand, when the pipeline 18 is eccentric at the measuring position, the spot offset from the center of the display surface of the monitor by the eccentricity of the pipeline 18 has the high light intensity or high brightness. Therefore, it can be confirmed whether or not the pipeline 18 is eccentric by monitoring the display surface of the monitor. The processing device 26 calculates the eccentricity of the pipeline 18 in the measuring position through the processing circuit on the basis of the output signal of the television camera 60, and the calculated eccentricity is stored in the memory together with the distance signal from the range finder 28. The eccentricity, for example, can be calculated by obtaining the coordinates of a portion of the light receiving plate 56 irradiated by the beam 20 in the X,Y cordinates of the light receiving plate 56 having the center as origin. Since the distance between lattices of the light receiving plate 56 is known, the eccentricity can be obtained by measuring actually or visually on the monitor the distance between the center of the latticed pattern on the monitor and the position with the high light intensity to multiply the measured value by the magnification of the monitor. By repeating the process of drawing back the slider 80 to the bed seat 70 to advance the detecting device 24 by a predetermined distance and the process of measuring the eccentricity, an operator can measure the eccentricity of the pipeline 18 without entering the inside of the pipeline 18. Further, it is possible to find the eccentric direction of the pipeline if the pipeline is eccentric. According to the inspection apparatus 10, the elongate members 66 are pressed against the inner surface of the pipeline 18 when the measurement is done so that the center of the light receiving plate 56 coincides with the center of the pipeline 18 in any measuring positions and thus the eccentricity can be accurately measured. Also, since the frame 44 is angularly rotated in the direction opposite to the rotational direction of the casing 32 relative to the casing 32 about the axis of the casing 32 such that the television camera 60 is located below by the weights of the frame 44 and television camera 60, even if the detecting device 24 is angularly rotated about the axis of the casing 32 relative to the pipeline 18, the orientations of the light receiving plate 56 and television camera 60 relative to the pipeline 18, i.e., the positional relationships among the pipeline, plate 56 and camera 60 in the vertical and horizontal directions are always constant. Accordingly, the eccentricity of the pipeline can be measured more accurately. The inspection apparatus 10 can obtain the inclination of a pipeline section between first and second measuring positions from the measured values in the first measuring position and the second measuring position, to which the detecting device 24 is moved from the first measuring position by a predetermined distance Δℓ. Namely, as shown in Fig. 14, assuming that coordinate values of the portion of the light receiving plate 56 irradiated by the beam 20 in the first measuring position 18₁ are X₁,Y₁ and the coordinate values of the portion of the light receiving plate 56 irradiated by the beam 20 in the second measuring position 18₂ spaced from the first measuring position 18₁ are X₂,Y₂, the inclination ϑx in the horizontal direction (X axis direction) and the inclination ϑy in the vertical direction (Y axis direction) can be obtained from the following formulas; tan ϑx = (X₁ - X₂)/Δℓ tan ϑy = (Y₁ - Y₂)/Δℓ Figs. 7 through 9 show an embodiment, in which the detecting device 24 shown in Fig. 2 is mounted on a self-propelled carriage 114 to move the detecting device 24 by the carriage 114, instead of moving the detecting device 24 with the wire. The carriage 114 comprises a truck or car body 116 extending back and forth and divided into the front and rear sections 116a,116b. In a plurality of spots spaced from each other in the longitudinal direction of the car body 116 are rotatably supported shafts 118,120,122 and 124 extending through the car body 116 widthwise thereof respectively. The respective shafts 118 through 124 have wheels 126 mounted on both ends and sprockets 128 mounted on the central portions respectively. On the foremost shaft 118 is mounted a bevel gear 130. The sprockets 128 of adjacent shafts are interconnected with a chain 132. A drive mechanism 134 is mounted on the foremost section of the car body 116 without interrupting the partial beam 20′. The drive mechanism 134 is provided with a rotary source 136 such as a motor, a reduction gear 138 connected to the output shaft of the rotary source and a gear 140 mounted on the output shaft of the reduction gear. The drive mechanisms 134 is supported by a gear case 142 mounted on the car body. Also, a shaft 144 rotatably extending back and forth through the foremost section of the car body 116 is rotatably supported by the foremost section of the car body 116. Gears 145,146 meshing respectively with the gears 130,140 are mounted on the shaft 144. The rotation of the rotary source 136 is transmitted to the shaft 118 through the reduction gear 138, gears 140,146, shaft 144 and bevel gears 145,130 and then transmitted from the shaft 118 to the other shafts 120,122 and 124 through the sprockets 128 and chain 132. The front and rear sections 116a,116b of the car body 116 are pivotably interconnected with each other within a predetermined angular extent by the shaft 118 and a connecting member 148 supported pivotably by the shaft 118. Thus, even if the pipeline 18 is bent vertically on the way, the carriage 114 moves smoothly. The detecting device 24 is mounted on the truck 116 by a support mechanisms 150 to be movable in the vertical direction. As shown in Figs. 7 and 10, the supported mechanism 150 is provided with a pair of arms 152 extending from the truck 116 sideways, a guide rod 154 fixed to the arm 152 and extending from the arm upward and a bracket 156 supported vertically movably by the guide rod 154 and fixed to the casing 32 of the detecting device 24. During the movement of the carriage 114, the slider 80 of the detecting device 24 is moved to the bed seat 70 and the the casing 32 contacts directly the truck 116 so that the elongate member 66 retreats to a position spaced from the pipeline 18. Thus, the elongate member does not interfere with the movement of carriage. When the measuring process is done, the slider 80 of the detecting device 24 is moved to the wall 40, so that the elongate member 66 is pressed against the inner surface of the pipeline 18. When the elongate member 66 is pressed against the inner surface of the pipeline 18, the detecting device 24 ascends along the guide rod 154 of the support mechanism 150. By so doing, the axes of the casing 32 and light receiving plate 56 are aligned with the center of the pipeline 18 in the stopping position of the detecting device 24, i.e., in the measuring position. A detecting device 158 shown in Fig. 11 is provided with a tubular body 38′ mounted coaxially on the tubular body 38, in which the light receiving body 50 is disposed, a light receiving body 50′ supported by the tubular body 38′ to be rotatable about the axis of the casing 32 and a connecting piece 62′ for connecting the light receiving body 50′ to the light receiving body 50 or connecting piece 62. Also, as shown in Fig. 12, a television camera 60′ for taking a picture of the light receiving body 50′ is further installed on the frame 44 in addition to the television camera 60 for the light receiving body 50. The output signal of the television camera 60′ is supplied to the processing device 26. The processing device 26 is further provided with a monitor for projecting the light receiving body 50′ on the basis of the output signal of the television camera 60′ in addition to the monitor corresponding to the television camera 60. Similarly to the light receiving body 50, the light receiving body 50′ is provided with a ring 54′ rotatably supported on portion 38′ by a plurality of rollers 52′ and a disk-like light receiving plate 56′ fixed to the ring 54′. As shown in Fig. 13(A), the light receiving plate 56 of the detecting device 158 has the right half made of a translucent material and the left half made of a transparent material, and a latticed pattern is drawn on the translucent right half. On the other hand, the light receiving plate 56′, as shown in Fig. 13(B), has the left half made of the translucent material and the right half made of the transparent material, and the latticed pattern is drawn on the translucent left half. The detecting device 158 uses first and second beams directed in parallel through portions spaced from each other in the horizontal direction of the pipeline 18. The first beam is directed so as to pass through the transparent right half of the light receiving plate 56′ and then irradiate the translucent right half of the light receiving plate 56. On the other hand, the second beam is directed so as to pass through the translucent left half of the light receiving plate 56′ and then irradiate the transparent left half of the light receiving plate 56. According to the detecting device 158, when the pipeline 18 is neither eccentric nor slant in the measuring position, the first and second beams irradiate predetermined portions of the light receiving plates 56,56′. However, when the pipeline 18 is eccentric, the portions of the light receiving plates 56,56′ irradiated by the first and second beams are displaced according to the eccentricity and eccentric direction of the pipeline 18. Thus, the eccentricity of the pipeline can be measured from the output signal of the television camera 60 or television camera 60′. Also, according to the detecting device 158, when the slant angle of the pipeline 18 differs from a predetermined slant angle in the measuring position, the portions of the light receiving plates 56,56′ irradiated by the first and second beams are displaced according to a variation of the slant angle of the pipeline 18. Thus, the variation of the slant angle of the pipeline 18 can be measured from the output signals of the television cameras 60,60′. This variation can be obtained as follows; Assuming that, as shown in Fig. 15, X1a and Y1a are coordinate values of a portion of the light receiving plate 56 irradiated by the first beam when the pipeline 18 is neither eccentric nor slant in the measuring position, X1b,Y1b are coordinate values of a portion of the light receiving plate 56 irradiated by the first beam when the pipeline 18 is eccentric or slant in the measuring position, X2a,Y2a are coordinate values of a portion of the light receiving plate 56′ irradiated by the second beam when the pipeline 18 is neither eccentric nor slant in the measuring position, X2b,Y2b are coordinate values of a portion of the light receiving plate 56′ irradiated by the second beam when the pipeline 18 is eccentric or slant in the measuring position, L is a distance between the light receiving plates 56,56′, ϑx is the variation of the slant angle in a horizontal direction and ϑy is the variation of the slant angle in a vertical direction, the variation of the slant angle of the pipeline can be obtained from the following formulas; tan ϑx = {(|X1b| - |X1a|) + (|X2a| - |X2b|)} ÷ L tan ϑy = {(|Y1b| - |Y1a|) + (|Y2a| - |Y2b|)} ÷ L

Claims: An apparatus for inspecting a pipeline by utilizing a beam (20) directed from one end of a pipeline (18) to the other to inspect whether or not said pipeline (18) is eccentric, comprising: detecting means (24, 158) disposed in said pipeline (18) to be movable along the axis of said pipeline (18) and provided with a tubular casing (32) disposed to extend in a direction along the axis of said pipeline (18), a light receiving body (50, 50') having a light receiving surface (56, 56') for receiving said beam, a maintaining mechanism (64) for maintaining releasably a position of said light receiving body (50, 50') relative to said inner surface such that the light receiving body (50, 50') has a predetermined positional relationship to the inner surface of said pipeline (18), said light receiving body (50, 50') and said maintaining mechanism (64) being supported by said casing (32); and means (26) for processing a signal to inspect whether or not said pipeline (18) is eccentric, characterized in that a television camera (60, 60') is provided for taking a picture of said light receiving body, said television camera (60, 60') being also supported by said casing (32) and providing output signals for processing by said means (26) and that said maintaining mechanism (64) is provided with a plurality of members (66) disposed around said casing (32) and connected to said casing (32) the positions of said members being variable on straight lines extending radially of said casing (32) and a drive mechanism (78) is provided for changing the positions of said members on the straight lines extending radially of said casing (32). An apparatus for inspecting a pipeline as claimed in claim 1, characterized in that each of said members (66) is an elongate member (66) extending along the axis of said casing (32) outside said casing (32) and connected to said casing (32) through a plurality of parallel links (68). An apparatus for inspecting a pipeline as claimed in claim 1, characterized in that said detecting means (24, 158) is further provided with a frame (44) disposed in said casing (32) and supported by said casing (32) to be rotatable about the axis of said casing (32), said television camera (60, 60') is supported by said frame (44), said light receiving body (56, 56') is supported by said casing (32) to be rotatable about the axis of said casing (32) and said frame (44) and said light receiving body (56, 56') are interconnected with each other without changing the relative positions. An apparatus for inspecting a pipeline is claimed in claim 1, characterized in that it further comprises a self-propelled carriage (114) disposed in said pipeline (18) to be movable along the axis of said pipeline (18) and mounting said detecting means (24, 158).

Inventors: NOBUNAGA, HIROSHI
Applicants: KABUSHIKI KAISHA ISEKI KAIHATSU KOKI
Application year: 1988
Main classification: G01B11
IPC codes: G01B11