JP2001255314A - Pipe interior inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe interior inspection device having an accurate distance measuring instrument strong against vibration. SOLUTION: Rollers 10 are supported in a freely rotatable manner by the shafts 11 inserted in the leading ends of supports 9 through spacers 12 and bearings 13 and have contact parts 10a having a large outer diameter and magnetizing parts 10b having a small outer diameter. Each contact part 10a comes into contact with the inner wall of a pipeline 1 and each magnetizing part 10b is magnetized so that the outer periphery thereof is alternately set to N- and S-poles. A magnetic sensor 14 is arranged to the leading end of each support 9 and the magnetic field generated from the magnetizing part 10b is detected at the leading end part thereof. When the roller 10 is rotated, the direction of the magnetic field detected by the magnetic sensor 14 is alternately changed and, therefore, sinusoidal output synchronous to the rotation of the roller 10 is generated from the magnetic sensor 14. A distance measuring instrument 8 pulsates this output to count pulses to measure a distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-pipe inspection apparatus that detects a flaw or pitting occurring in a pipe and photographs a situation in the pipe.

[0002]

2. Description of the Related Art In-pipe inspection apparatuses called inspection pigs have been used to detect defects that occur in gas pipes, oil transportation pipes and the like buried underground. Inspection pigs are equipped with a defect detection device inside and run inside the pipe for inspection.As a large-scale inspection pig, in addition to the defect detection device, a data recording device and a power supply are installed inside, It travels in a pipe by being pushed by a transportation medium such as oil, and several hundred km
Inspections that perform inspections over long distances have also been put to practical use. As an inspection pig, a type equipped with a camera or a video camera and imaging a state in a pipe has been developed. One example of such an inspection pig is disclosed in JP-A-63-221.
No. 240 is described.

[0003] If a serious defect is found by an in-pipe inspection device, the location must be repaired. In the case of an underground pipe, it is particularly important to accurately specify the location where the defect exists, because it is necessary to dig the location to perform the repair. For this purpose, the in-pipe inspection device is usually provided with a distance measuring device. Some distance measuring devices use the inertial method, but commonly used is a so-called odometer that measures the distance traveled by measuring the rotation of a roller that rotates in contact with the inner wall of the pipe. It is said to be.

A typical odometer conventionally used is a trolley in which a roller is coupled to a lorry encoder. The odometer measures the traveling distance by counting pulses from the rotary encoder generated by rotation of the roller. is there.

[0005]

However, commercially available rotary encoders produce pulses synchronized with rotation by detecting light of a photodiode through a rotating slit with a photocell, and are thus vulnerable to vibration. There is a point. In addition, the inside of the pipe in which the in-pipe inspection apparatus travels is often at a high pressure, and there is a problem that a commercially available rotary encoder cannot withstand such a high pressure.

As a countermeasure, a disk having a plurality of notches or holes on the same circumference is directly connected to a roller rotating in contact with the pipe wall, and these notches or holes are detected by a proximity switch. Attempts have been made to detect the rotation of the roller, but there is a problem in that the accuracy of the measurement is reduced because the pitch of the notch or hole formed in the disk cannot be reduced.

Further, when trying to measure the running distance using an odometer, an error due to slip between the roller and the pipe wall is inevitable. This error accumulates as the mileage of the in-pipe inspection device increases, and can be quite large near the exit. Therefore, it is preferable to minimize this slip amount.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide an in-pipe inspection apparatus which is resistant to vibration and has an accurate distance measuring apparatus.

[0009]

A first means for solving the above-mentioned problem is an in-pipe inspection device which travels in a pipe and inspects a state of the pipe, and rotates in contact with an inner wall of the pipe. A distance measuring device that measures the moving distance by detecting the rotation of the roller, the distance measuring device is directly connected to the roller, and the circumference is alternately magnetized with opposite characteristics; And a pulse generator that generates a pulse according to the signal of the magnetic sensor, and measures the distance by counting the pulses generated with the rotation of the roller. The in-pipe inspection device according to claim 1, wherein the disk and the magnetic sensor do not have an outer shell for protecting the disk and the magnetic sensor.

In this means, when the roller rotates, the disk directly connected to the roller rotates. Since the magnetic sensor detects a magnetic signal from a magnetized area around the disk, it generates an AC signal synchronized with the rotation of the roller. By pulsing and counting this AC signal, the traveling distance can be measured.

In this means, the disk and the magnetic sensor are exposed without having an outer shell for accommodating the disk and the magnetic sensor. Since the pressure resistance of the magnetic sensor is sufficient, there is no breakage in this case. Further, since these structures of the distance measuring device in the present means do not have a precise mechanical part, they can be made strong against vibration. Furthermore, since the magnetization around the disk can be performed at a sufficiently fine pitch, the measurement accuracy can be improved.

A second means for solving the above-mentioned problem is as follows.
In the first means, the magnetic sensor detects the magnetism of the magnetized disk and generates sine waves having phases different from each other by 90 °. Among them, a pulse generator that generates a pulse every time the direction of a vector having one as an x-axis component and the other as a y-axis component rotates by a predetermined angle is provided, and the distance is measured by counting the pulses. Features (Claim 2)
It is.

As described above, the resolution can be greatly improved as compared with the case where one magnetic sensor is used, as will be described in detail in the section of the embodiment of the invention.

A third means for solving the above-mentioned problem is as follows.
An in-pipe inspection device that travels in a pipe and inspects a state of the pipe, the distance having a distance measuring apparatus that measures a moving distance by detecting rotation of a roller that rotates in contact with an inner wall of the pipe, the roller Is an in-pipe exploration device (claim 3) characterized in that its periphery is magnetized to generate a suction force between the pipe and a magnetic body.

In this means, since the roller is magnetized and generates a suction force between the roller and the pipe made of a magnetic material, the frictional force between the pipe wall and the roller pipe is increased by the force, and the roller slips. Can be reduced. Therefore, accurate distance measurement can be performed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows Embodiment 1 of the present invention.
It is a figure which shows the outline | summary of the in-pipe inspection apparatus which is an example, (a) is the schematic diagram of a longitudinal cross section, (b) is the schematic diagram seen from back. FIG.
, 1 is a pipeline, 2 is an in-pipe inspection apparatus, 3 is an outer body, 4 is a scraper cup, 5 is a defect inspection apparatus,
Reference numeral 6 denotes a storage device, 7 denotes a weight position detecting device, 8 denotes a distance measuring device, 9 denotes a support, and 10 denotes a roller.

The outer shell of the in-pipe inspection device 2 is supported by a scraper cup 4 made of an elastic material such as polyurethane, and travels through the pipeline 1 by being pushed by a fluid. The outer body 3 contains a defect inspection device 5, a storage device 6, a weight-type position detection device 7, a distance measurement device 8, and the like. In addition, a power supply device, a circumferential weld detector, a marker detector, and the like are housed, but illustration thereof is omitted.

The defect inspection apparatus 5 detects a defect existing in the pipeline 1 by using an ultrasonic flaw detection method, a leakage magnetic flux flaw detection method, an eddy current flaw detection method, or the like. The weight-type position detection device 7 detects the posture of the in-pipe inspection device 2, that is, which position is directly above in the circumferential direction. The distance measuring device 8 measures the traveling distance of the in-pipe inspection device 2. The outputs of the defect inspection device 5, the weight type position detecting device 7, the distance measuring device 8, etc. are stored in the storage device 6.
After the inspection is completed by the in-pipe inspection device 2 and taken out of the pipeline 1, the storage in the storage device 6 is reproduced and subjected to data processing, so that the defect occurrence position and the defect circumferential position , The size of the defect and the like are analyzed.

The defect inspection device 5, the storage device 6, and the weight-type position detection device 7 are well-known devices, and since many documents have been published, their description will be omitted. Behind the shell 3,
A roller 10 supported by a support 9 is provided. The support 9 is urged toward the pipe wall of the pipeline 1 by an elastic body (not shown), and the roller 10 is pressed against the inner wall of the pipeline 1 by this urging force. The periphery of the roller 10 is magnetized, and generates a suction force between the roller 10 and the inner wall of the pipeline 1. Therefore,
The urging force and the suction force are added to increase the frictional force between the inner wall of the pipeline 1 and the roller 10, and the roller 1
0 is hard to slip.

When the in-pipe inspection device 2 runs, the rollers 1
0 rotates, and the rotation is measured by the distance measuring device 8. More specifically, the distance measuring device 8 measures a traveling distance by counting pulses from a pulse transmitter (not shown) attached to the roller 10.

In the present embodiment, a total of four sets of the supports 9 and the rollers 10 are provided every 90 ° in the circumferential direction, and the outputs from the respective pulse transmitters are input to the distance measuring device 8. ing. The distance measuring device 8 selects and counts the pulse with the highest pulse rate, that is, the pulse from which the slip amount is considered to be small among the pulses from the four pulse transmitters.

FIG. 2 is an enlarged view of the vicinity of the support 9 and the roller 10. (a) is a sectional view, and (b) is a side view. FIG.
In the figure, 10a is a contact portion, 10b is a magnetized portion, 11 is a shaft, 12 is a spacer, 13 is a bearing, and 14 is a magnetic sensor.

The tip of the support 9 is bifurcated,
The shaft 11 is fitted therein. The roller 10 is rotatably supported on the shaft 11 via a spacer 12 and a bearing 13. The roller 10 has a contact portion 10 having a large outer diameter.
a and a magnetized portion 10b having a small outer diameter. The contact portion 10a is a portion that contacts the inner wall of the pipeline 1,
In this embodiment, the outer peripheral portion is also magnetized, and the frictional resistance is increased by the attraction force with the tube wall.

The outer periphery of the magnetized portion 10b is alternately N-pole,
It is magnetized to the south pole. The magnetic sensor 14 has a support 9
And detects a magnetic field generated from the magnetized portion 10b at the tip. When the roller 10 rotates, the direction of the magnetic field detected by the magnetic sensor 14 changes alternately, so that a sine wave output synchronized with the rotation of the roller 10 is generated from the magnetic sensor 14. The distance measuring device 8 performs distance measurement by pulsing this output and counting.

As described above, in the present embodiment, both the magnetic sensor 14 and the magnetized portion 10b of the roller 10 are exposed, but since these are strong against environmental resistance and vibration, no problem occurs. . In this embodiment, a disk portion magnetized for measuring the rotation of the roller 10, that is, a magnetized portion 10 b and a portion 10 a that comes into contact with the tube wall are integrally formed. Needless to say, they may be connected by an axis.

Next, using two magnetic sensors,
A method of generating two signals having phases different from each other by 90 ° by the magnetic field of 0b to increase the resolution of distance measurement will be described. FIG. 3 shows a magnetic sensor 1 of this type.
FIG. 4 is a diagram showing details of No. 4 and an output waveform thereof. In FIG. 3, reference numerals 14a to 14d denote coils for detecting a magnetic field.
a, 14b and 14c, 14d are wound in opposite directions, and the differential output of the coils 14a and 14c is A,
The differential output of b and the coil 14d is extracted as B.
Assuming that the pitch of the magnetization of the magnetized portion 10b is C, the coil 14
a and the coil 14b, and the coil 14c and the coil 14d are separated by (n−3 / 4) C (n is a natural number), and the differential output A and the differential output B have a 90 ° phase difference. It is designed to be a sine wave. FIG. 3 shows a case where n = 1.

For example, as shown in FIG. 4A, it is assumed that the magnetized portion 10b is divided into 16 portions and magnetized. That is, in the magnetized portion 10b, 16 N poles and 16 S poles are alternately arranged. In such a case, the magnetic sensor 1
When a Lissajous figure having the A output as the x-axis component and the B output as the y-axis component is written as a circle as shown in FIG. 4B, the A output is defined as the x-axis component, and the B output is defined as the y-axis component. The tip of the moving vector makes a uniform circular motion.

Therefore, sin ^-1 (B
/ A) is calculated, and a pulse generator for generating a pulse every time this value increases by a predetermined value is provided. In FIG. 4B, one pulse is generated every time the vector rotates by 9 °. The vector makes one rotation each time one N-pole of the magnetized part 10b passes through the predetermined position, and thus makes 16 rotations each time the magnetized part 10b makes one rotation. Then, since one pulse is output every time the vector rotates 9 °, 640 pulses are output every time the magnetization unit 10b makes one rotation. In this way, even if the magnetization mesh of the magnetization part 10b is roughened, many pulses can be extracted, and as a result, the resolution of the distance can be increased.

[0029]

As described above, according to the first aspect of the present invention, the sensor section of the distance measuring device can be made resistant to vibration and the environment, and the measurement accuracy can be further improved. be able to.

In the invention according to claim 2, the resolution can be greatly improved as compared with the case where one magnetic sensor is used.

According to the third aspect of the present invention, slippage of the roller can be reduced. Therefore, accurate distance measurement can be performed.

[Brief description of the drawings]

FIG. 1 is a view showing an outline of an in-pipe inspection apparatus which is an example of an embodiment of the present invention.

FIG. 2 is an enlarged view of the vicinity of a support and a roller in the embodiment shown in FIG.

FIG. 3 is a diagram showing a structure of a magnetic sensor having two outputs and a positional relationship with a magnetized part.

FIG. 4 is a diagram illustrating a principle of increasing resolution using two magnetic sensor outputs.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pipeline, 2 ... In-pipe inspection apparatus, 3 ... Outer body, 4
... Scraper cup, 5 ... Defect inspection device, 6 ... Storage device, 7 ... Position type position detecting device, 8 ... Distance measuring device, 9 ...
Support, 10 ... Roller, 10a ... Contact, 10b ...
Magnetized part, 11 ... shaft, 12 ... spacer, 13 ... bearing, 14
... Magnetic sensors, 14a-14b ... Coils

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G01N 21/954 G01N 21/954 A 27/83 27/83 27/90 27/90 F term (reference) 2F024 AA16 AB07 2F077 AA25 CC02 CC08 NN02 NN19 NN24 PP06 QQ05 QQ10 VV02 2G047 AB01 BC07 DB18 GA19 GA20 GJ08 2G051 AA37 AB02 AC17 CA02 DA06 DA09 2G053 AA11 AB01 AB21 AB22 BA12 BA26 BC02 BC05 BC14 CA03 CB25 DA01 DB05 DB06 DB20

Claims (3)

[Claims] 1. An in-pipe inspection apparatus that travels in a pipe and inspects a state of the pipe, the distance measuring apparatus measuring a moving distance by detecting rotation of a roller that rotates in contact with an inner wall of the pipe. The distance measuring device has a disk directly connected to the roller and the periphery of which is alternately magnetized with opposite characteristics, a magnetic sensor that detects the magnetism of the disk, and a pulse according to a signal from the magnetic sensor. It has a pulse generator that generates, and measures the distance by counting the pulses generated with the rotation of the roller, wherein the disk and the magnetic sensor do not have an outer shell that protects it An in-pipe inspection device, characterized in that: 2. The in-pipe inspection apparatus according to claim 1, wherein the magnetic sensor detects the magnetism of the magnetized disk and generates sine waves having phases different from each other by 90 °. One of the two sine waves having different phases is represented by x
In-pipe inspection characterized in that it has a pulse generator that generates a pulse each time the direction of a vector having the other axis component as the y-axis component rotates by a predetermined angle, and measures the distance by counting the pulses. apparatus. 3. An in-pipe inspection device that travels in a pipe and inspects a state of the pipe, wherein the distance measuring apparatus measures a moving distance by detecting rotation of a roller rotating in contact with an inner wall of the pipe. The inside-pipe exploration device, wherein the roller has a magnetized periphery and generates a suction force between the roller and a pipe made of a magnetic material.