JP2000214137A - Pipe interior inspection method and pipeline interior inspection device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Even when a pipe to be inspected is, for example, a long pipe of about 250 m, reflected sound waves can be clearly extracted, and the internal state of the pipe at a distant point is determined. Provided are a method and an apparatus for inspecting the inside of a pipe by using sound waves, which can be accurately detected. SOLUTION: A sound wave is made incident from a conduit duct opening, and a reflected wave from the inside of the conduit for the incident sound wave is received,
A method for inspecting the inside of a pipe by a sound wave for inspecting the state of the inside of the pipe based on the received reflected wave, wherein the incident sound wave for inspecting the inside of the pipe at a distant point from the pipe duct opening is a complex and periodic artificial sound. Incident sound wave (7
Use 6). In addition, the incident sound wave (76) for inspecting the inside of the pipeline at a point distant from the duct duct opening, and the incident acoustic wave (7) for inspecting the inside of the pipeline at a short distance from the opening of the duct duct.
5) The two types of incident sound waves are used together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting the inside of a pipeline, and more particularly to a method of measuring a reflected acoustic wave by radiating a sound wave into a pipeline such as an underground pipeline for accommodating a communication cable. The present invention relates to a method and a device for inspecting the inside of a pipe, which can easily check the state of the inside of the pipe.

[0002]

2. Description of the Related Art FIG. 7 is a view for explaining a conventional apparatus for inspecting the inside of a pipeline using sound waves. In the conventional pipeline interior inspection device shown in FIG. 7, first, a speaker mounted in a sound wave transmitting / receiving device 2 installed in a pipeline duct opening is used by a speaker control signal generated in the device main body 1. , Underground pipeline 4 buried via manhole 3
A sound wave is incident on the inside. Next, a reflected sound wave reflected at the location (5, 6) of the cross-sectional area of the pipeline existing in the underground pipeline 4 or at the pipe end is received by the microphone mounted in the sound wave transmitting / receiving device 2. Then, the arrival time and the reflected sound waveform of the received reflected sound waves are
The analysis and measurement are performed in the above, and the internal state of the underground pipeline 4 is inspected. Here, as an incident sound wave entering the inside of the underground conduit 4, a sound wave having a monocycle pulse waveform as shown at 21 in FIG. 8 is generally used. Such a technique is disclosed, for example, in Japanese Patent Application Laid-Open No. 7-55931 (method and apparatus for measuring the internal state of a pipeline).

[0003]

FIG. 9 shows an example of the reflected sound waveform when the underground pipe 4 is inspected by the conventional inspection apparatus for the inside of a pipe using sound waves shown in FIG. In the conventional pipe interior inspection device shown in FIG. 7, the reflected sound wave 32 at the pipe end when the incident sound wave 31 enters the underground pipe 4 and the reflection at the cross-sectional area change location existing in the underground pipe 4. The phase and amplitude of the sound wave 33 with respect to the incident sound wave 31 are used to measure the state and extent of the change in the cross-sectional area at the location where the reflection occurs, and the reflected sound waves (32, 33) after the incident sound wave 31 enters the underground conduit. By measuring the time until the input sound reaches the microphone, the distance from the incident position of the incident sound wave 31 to the position where the reflection has occurred is measured. On the other hand, the communication cable accommodating pipeline currently in use has a maximum length of 250 m. However, when the underground pipeline 4 is inspected by the conventional acoustic line interior inspection device shown in FIG. 7, the longer the length of the underground pipeline 4 to be inspected, the more the incident acoustic wave 31 is inspected. The reflected sound wave 33 at the cross-sectional area change point located far from the incident position is so indistinguishable from noise from the outside that it is indistinguishable due to the attenuation due to the sound wave distance and the effect of multiple reflections at the cross-sectional area change point in the pipeline. There is a problem that it is difficult to specify the position of the disturbance or the cross-sectional area change point. The present invention has been made in order to solve the problems of the prior art,
It is an object of the present invention to accurately detect the internal state of a pipe at a distant point by allowing reflected sound waves to be clearly extracted even when the pipe to be inspected is, for example, a long pipe of about 250 m. It is an object of the present invention to provide a method and an apparatus for inspecting the inside of a pipeline by using a sound wave. The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0004]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows. That is, according to the present invention, a sound wave enters from a duct duct opening, receives a reflected wave from the inside of the duct with respect to the incident sound wave, and checks the inside condition of the duct based on the received reflected wave. An inspection method, characterized in that an incident sound wave having a complex and periodic artificial characteristic is used as an incident sound wave for inspecting the inside of a pipe at a point distant from a pipe duct opening. In addition, the present invention provides a pipe interior for receiving a sound wave from a pipe duct opening, receiving a reflected wave from the inside of the pipe with respect to the incident sound wave, and checking a pipe internal state based on the received reflected wave. An inspection method in which two types of incident sound waves are used: an incident sound wave for inspecting the inside of a pipe at a point far from the duct duct entrance and an incident sound wave for inspecting the inside of the conduit at a point near the duct duct opening. It is characterized by the following. Further, according to the present invention, the incident sound wave for inspecting the inside of the conduit at a short distance from the conduit duct opening and the incident acoustic wave for inspecting the inside of the conduit at a point far from the conduit duct opening are individually and sequentially incident. Then, the reflected sound waveforms for the incident sound waves are separately output, and the internal state of the pipeline is checked for each distance. Further, the present invention provides an incident means for injecting a sound wave from a duct duct opening,
Receiving means for receiving a reflected wave from the inside of the pipe with respect to the sound wave incident from the incident means, and checking means for checking the state of the inside of the pipe based on the reflected wave received by the receiving means; An inspection device, wherein the incident means is configured to output incident sound waves having complex and periodic artificial characteristics from the conduit duct opening as incident acoustic waves for inspecting the inside of the conduit at a point distant from the conduit duct opening. It is characterized in that it enters the inside of the road. Further, the present invention provides an incident means for receiving a sound wave from a conduit duct opening, a receiving means for receiving a reflected wave from the inside of the conduit for the sound wave incident from the incident means, and a reflection received by the receiving means. A pipe interior inspection device having inspection means for inspecting the internal state of a pipeline based on a wave, wherein the incident means includes an incident sound wave for inspecting the interior of the pipeline at a long distance from the pipeline duct opening, 2 with incident sound wave for inspection inside the pipeline at a short distance from the duct opening
It is characterized in that various types of incident sound waves enter the inside of the pipeline from the pipeline duct opening. Further, in the present invention, the incident means may include an incident sound wave for inspecting the inside of the pipeline at a short distance from the duct duct opening, and an incident acoustic wave for inspecting the inside of the conduit at a point far from the duct duct opening, Each of the light beams is sequentially and individually incident, and the inspection means inspects the internal state of the pipeline for each distance. Further, the present invention is characterized in that the incident sound wave for inspecting the inside of the pipe at a point far from the pipe duct opening is a sound wave having a dual cycle pulse waveform.

[0005]

Embodiments of the present invention will be described below in detail with reference to the drawings. In all the drawings for describing the embodiments, components having the same functions are denoted by the same reference numerals, and repeated description thereof will be omitted. [First Embodiment] FIG. 1 is a block diagram showing a schematic configuration of an apparatus for inspecting the inside of a pipeline using sound waves according to an embodiment of the present invention. As shown in the figure, the pipeline interior inspection device of the present embodiment includes an arithmetic processing unit 10, a display unit 11, an operation unit 12, a digital unit 13, an analog unit 14, and a probe unit 15. Here, the arithmetic processing unit 10 includes the CPU 101
And a memory 102.
Are the D / A converter 105 and the A / D converter (106, 1).
08) and a time-varying gain controller 107. Further, the analog section 14 includes the speaker driving amplifier 1
09, a microphone amplifier 110, and a temperature sensor amplifier 11
The probe unit 15 includes a speaker 1
12, a microphone 113, and a temperature sensor 114.

Further, a display 10 is provided on the display unit 11.
The operation unit 12 includes an operation switch 104.

[0007] In the pipe line inspection apparatus of the present embodiment, C
Under the control of the PU 101, the waveform data of the incident sound wave entering the inside of the pipeline is sent to the D / A converter 105, where the D / A
After being converted into an analog signal by the converter 105, the signal is amplified by the speaker drive amplifier 109, and a sound wave enters the inside of the pipe from the speaker 112. The reflected sound wave from the inside of the pipe with respect to the incident sound wave is received by the microphone 113, amplified by the microphone amplifier 110, sent to the A / D converter 106, and converted into digital data by the A / D converter 106. It is converted and stored in the memory 102. In this case, the microphone amplifier 110 is controlled by a control signal from the time-varying gain controller 107 controlled by the CPU 101 so that its gain (amplification degree) increases with time. Further, the temperature detected by the temperature sensor 114 is also amplified by the temperature sensor amplifier 111, sent to the A / D converter 108, and sent to the A / D converter 108.
Is converted into digital data and stored in the memory 102. The temperature data detected by the temperature sensor 114 is used as a parameter when measuring the distance from the speed of sound.

In the pipe line inspection apparatus of this embodiment, two sound waves, a short-range incident sound wave for short-range measurement and a long-range incident sound wave for long-range measurement, are used. here,
A monocycle pulse waveform sound wave is used as the near-field incident sound wave, and a pulse waveform sound wave having complex and periodic artificial features is used as the long-range incident sound wave. That is, in the present embodiment, as a long-range incident sound wave, a sound wave 41 having a pulse waveform having a complex and highly periodic artificial characteristic as shown in FIG. 2 is used, and as a short-range incident sound wave, A sound wave 42 having a monocycle pulse waveform is used. In general, the probability of existence of noise that is sudden and repeats the same waveform in nature is extremely low. Therefore, as in the present embodiment, a pulse having complex and periodic artificial features as incident sound waves is used. By using the sound wave 41 having a waveform, the longer the distance is, the easier it is to distinguish between reflected sound waves and noise. Also, the sound wave 4 having the pulse waveform shown in FIG.
As shown in FIG. 1, when the property of the incident sound wave is artificial, complicated and periodic, the absolute value of the power spectrum of the incident sound wave becomes larger than that of the sound wave 42 having the monocycle pulse waveform, and the influence of attenuation due to the distance is obtained. The disturbance of the signal waveform of the incident sound wave due to is reduced. Furthermore, if the signal waveform of the incident sound wave has a complicated periodicity, a plurality of peaks of the reflected sound wave can be obtained in a narrow range, and the peak detection processing of the reflected sound wave becomes easy. That is, when the sound wave 41 having a monocycle pulse waveform is used, the number of peaks of the reflected sound wave is 1, and when the amplitude is small, it may not be possible to discriminate the noise. However, the signal waveform of the incident sound wave has a complicated periodicity. With this, even when the inspection target distance is long, the reflected sound wave can be clearly recognized as compared with the case where the sound wave 41 having the conventional monocycle pulse waveform is used.

FIG. 3 shows a reflected sound waveform 51 when a sound wave 41 having a monocycle pulse waveform is used as an incident sound wave.
7 shows a reflected sound waveform 52 in the case of using a long-range incident sound wave (that is, a sound wave 41 having a pulse waveform having a complex and highly periodic artificial characteristic). In the graph of FIG.
The vertical axis indicates the amplitude of the reflected sound wave, and the horizontal axis indicates the distance (meter) from the duct opening. As is clear from FIG.
The reflected sound wave waveform near the pipe end 250 m ahead is a reflected sound wave 51 using a monocycle pulse wave sound wave as an incident sound wave.
It is shown that the reflected sound wave 52 using the incident sound wave for a long distance as the incident sound wave has less waveform disturbance. The reflected sound waves (51, 52) shown in FIG. 3 are obtained after being amplified by the time-varying gain controller 107 that changes the amplification factor with time.

[0010] Further, in the pipe interior inspection apparatus of the present embodiment, the inspection target range when the long-range incident sound wave is incident is applied to a place farther than a place somewhat distant from the incident position of the incident sound wave. For the inspection of the close distance from the incident position of the incident sound wave, the short-range incident sound wave (that is, the sound wave 42 having a monocycle pulse waveform) is used.
FIG. 4 shows a reflected sound waveform 64 due to a long-distance incident sound wave and a reflected sound waveform 65 due to a short-distance incident sound wave at a cross-sectional area change point 62 at a short distance from the sound wave incident position.
Is shown. When the method using the long-range incident sound wave alone as the incident sound wave 63 is adopted, as shown in FIG. 4, a pipe 61 existing at an extremely short distance from the incident position of the incident sound wave 63 is used.
Since the reflected sound wave waveform of the cross-sectional area change portion 62 in the inside is combined with the incident sound wave waveform, processing such as peak detection becomes difficult, and as a result, it is difficult to specify the position where the reflected sound wave is generated. Therefore, for inspection of the inside of a pipe at a short distance, another incident sound wave having a smaller pulse width than that of the incident sound wave for a long distance (that is, a sound wave 4 having a monocycle pulse waveform).
The use of 2) makes it easier to detect the peak of the reflected sound wave at a point where the internal cross-sectional area of the conduit changes (for example, 62 in FIG. 4) at a closer distance than when the incident sound wave for long distance is used alone. As a result, the inspection of the inside of the pipeline at a short distance can be performed more accurately. Also,
At the shortest distance, there is almost no effect of sound wave attenuation due to the distance, so that an incident sound wave having a simple signal waveform can be used.

As described above, when the inspection is limited to the inside of the pipeline at a short distance from the sound wave incident position, the use of the short-range incident acoustic wave makes it possible to obtain the peak of the reflected acoustic wave at a location where the cross-sectional area inside the pipeline changes. It is understood that the detection becomes easy, and as a result, the inspection inside the pipeline at a close distance can be performed more accurately. Further, in the pipeline interior inspection device of the present embodiment, the short-range incident sound wave and the long-range incident sound wave are sequentially incident, and each reflected sound wave waveform is separately output,
When evaluating the results of inspections inside the pipeline, reflected sound waves due to incident sound waves for long distances are used for inspections at a position distant from the duct opening to some extent, and close-up inspections are performed for areas within a short distance from the duct opening. The inspection result is evaluated from each reflected sound wave waveform using the reflected sound wave due to the incident sound wave for distance. This allows the operator to easily check the reflected sound waves in the entire range of the pipeline including the short distance and the long distance.

FIG. 5 is a flowchart showing a processing procedure of the pipe interior inspection device of the present embodiment. Hereinafter, the processing procedure of the pipeline interior inspection device of the present embodiment will be described with reference to FIG. First, a waveform data file storing waveform data for a short distance incident on the inside of the pipeline is selected, and an incident sound wave for a short distance incident on the interior of the pipeline is set (step 201). Similarly, select the waveform data file that stores the long-distance waveform data that enters the pipeline,
A long-range incident sound wave that enters the inside of the pipe is set (step 202). Next, a measurement start button in the operation switch 104 is pressed (step 203). Next, the process of transmitting the short-range incident sound wave set in step 201 into the pipeline (step 204) and receiving the reflected sound from the pipeline (step 205) is performed one or more times. Then, in order to remove noise, an addition averaging process of the reflected sound waveform is performed (step 206). Next, step 206
Is stored in the memory 102 (step 210), and the arithmetic processing unit 10 performs short-range waveform analysis and measurement (step 212).

Next, the long-distance incident sound wave set in step 202 is transmitted into the pipe (step 207),
In order to execute the process of receiving the reflected sound from the inside of the pipe (step 208) one or more times and remove the noise,
An averaging process of the reflected sound waveform is performed (step 20).
9). Next, the reflected sound waveform data obtained in step 209 is stored in the memory 102 (step 210), and the arithmetic processing unit 10 performs long-distance waveform analysis and measurement (step 2).
12).

Next, as an example of an inspection method using the pipeline internal inspection device of the present embodiment, an experimental pipeline 71 shown in FIG.
In contrast, a description will be given of an inspection method using the pipeline interior inspection device of the present embodiment. As shown in the figure, the pipe 71 includes a section 73 where the cross-sectional area of the foreign matter 72 or the joint is increased, and a section 74 where the cross-sectional area is reduced due to rust at the joint as the cross-sectional area change in the pipe. And First, the short-range incident sound wave and the long-range incident sound wave are separately and sequentially incident on the pipeline 71 as shown in the flowchart of FIG. In this case, as described above, in order to perform noise elimination by the integration averaging method, each incident sound wave is automatically incident several times. In the present embodiment, the sound wave 7 having a monocycle pulse waveform is used as the short-range incident sound wave.
5 is a long-range incident sound wave (that is, a sound wave 76 having a pulse waveform having a complex and periodic artificial characteristic) and a sound wave 76 having a two-cycle dual cycle pulse waveform.

After each sound wave is incident, a reflected sound wave waveform 77 of the short-range incident sound wave and a reflected sound wave waveform 78 of the long-range incident sound wave are obtained and output separately. Subsequently, of the reflected sound waveform 77 of the short-range incident sound wave, a reflected sound waveform 79 in a section from the incident sound wave incident position to the close distance do.
Of the reflected sound waveform 78 of the long-range incident sound wave, do
The reflected sound wave waveform is analyzed using the reflected sound wave waveform 80 in the section up to the pipe end, and an inspection result 81 is obtained. The inspection result 81 shows the results of measuring the cross-sectional area change points (72, 73, 74) and the positions of the pipe ends existing in the pipe line 71.

In the above embodiment, a monocycle pulse waveform sound wave was used as the short-range incident sound wave, and a dual cycle pulse waveform sound wave was used as the long-range incident sound wave waveform, but within the range satisfying the gist of the present invention. If so, it goes without saying that a signal waveform of the incident sound wave other than that shown in this embodiment may be used. Further, in the above-described embodiment, the present invention has been described as an example in which the present invention is applied to the inspection of the underground conduit for accommodating a communication cable.
It is needless to say that the present invention can also be applied to a device for inspecting the inside of a pipe by a normal sound wave such as a water pipe. As described above, the invention made by the inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and can be variously modified without departing from the gist of the invention. Of course, it is.

[0017]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows. (1) According to the present invention, an incident sound wave having a complicated and periodic artificial characteristic is used as a sound wave for detecting the state of the inside of a pipe at a distant point. The waveform of the reflected wave from the distance point can be clearly extracted, and the state inside the pipe at the long distance point can be accurately detected. (2) According to the present invention, the near-field incident sound wave is used as the sound wave for detecting the state of the inside of the pipeline at the closest point, so that the waveform of the reflected wave from the near point inside the pipe is clearly defined. And it is possible to accurately detect the state of the inside of the pipeline at the closest point. (3) According to the present invention, it is possible to obtain the inspection result of the closest point inside the pipeline and the inspection result of the distant point inside the pipeline at one time, and it is possible to simplify the inspection work. Become.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an apparatus for inspecting the inside of a pipeline using sound waves according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing a long-distance incident sound wave and a short-distance incident sound wave used in the pipeline interior inspection device according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating an incident sound wave for a long distance and an incident sound wave for a short distance in the pipe interior inspection device according to the embodiment of the present invention;
6 is a graph for explaining a difference in a reflected sound wave waveform in a portion other than a close distance.

FIG. 4 is a diagram illustrating an incident sound wave for a long distance and an incident sound wave for a short distance in the pipe interior inspection device according to the embodiment of the present invention;
It is a figure for explaining a difference of a reflected sound wave waveform in a close distance.

FIG. 5 is a flowchart showing a processing procedure of the pipeline interior inspection device according to the embodiment of the present invention.

FIG. 6 is a diagram for explaining an example of an inspection method by the pipeline interior inspection device according to the embodiment of the present invention.

FIG. 7 is a diagram for explaining a conventional pipe line interior inspection device using sound waves.

FIG. 8 is a waveform diagram showing an example of incident sound waves used in the conventional pipeline interior inspection device shown in FIG.

FIG. 9 is a waveform chart showing an example of a reflected sound wave waveform obtained by the conventional pipe interior inspection device shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Device main body, 2 ... Sound wave transmission / reception device, 3 ... Manhole,
4 ... Underground pipeline, 5, 6 ... Change in pipeline cross-sectional area, 10 ... Operation processing unit, 11 ... Display unit, 12 ... Operation unit, 13 ... Digital unit, 14 ... Analog unit, 15 ... Probe unit, 21,
42,75 ... sound wave of monocycle pulse waveform, 31,6
Reference numeral 3 denotes an incident sound wave, 32 denotes a reflected sound wave at a tube end, 33 denotes a reflected sound wave at a cross-sectional area changing portion, 41, 76 denotes a sound wave having a dual cycle pulse waveform, and 51 denotes a case where a sound wave having a monocycle pulse waveform is used as the incident sound wave. Reflected sound wave waveform, 52: reflected sound wave waveform when an incident sound wave for long distance is used, 61, 71: conduit, 62: cross-sectional area change point at close distance, 64 ... reflected sound wave at short distance by incident sound wave for long distance Waveform, 65: Reflected sound wave at short distance by short-range incident sound wave, 72: Foreign matter, 73: Cross-sectional area enlarged position, 74: Cross-sectional area reduced position, 77: Reflected sound wave waveform of short-range incident sound wave, 78: Far Reflected sound waveform of the incident sound wave for distance, 79 ... reflected sound wave waveform in the section from the incident sound wave incident position to the closest distance do, 80 ... reflected sound wave waveform in the section from do to the pipe end, 8 ... inspection result, 101 ... CPU, 1
02: memory, 103: display, 104: operation switch, 105: D / A converter, 106, 108: A /
D converter, 107 ... time-varying gain controller, 109 ...
Speaker drive amplifier, 110 ... Microphone amplifier, 111 ...
Temperature sensor amplifier, 112: speaker, 113: microphone, 114: temperature sensor.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Takatsuka 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo F-term in Nippon Telegraph and Telephone Corporation (reference) 2F068 AA06 AA49 BB09 CC00 DD03 EE02 FF03 FF12 FF25 GG01 KK14 PP05 2G047 AB01 BA03 BC02 BC18 DB18 EA09 GA18 GF06 GG16 GG19 5J083 AA02 AB20 AC09 AC29 AD01 AD04 AD22 AE10 AG10 BA01 BE49 CA02 CA10

Claims (8)

[Claims] 1. A sound wave is incident from a conduit duct opening, and a reflected wave from the inside of the conduit for the incident sound wave is received.
A method for inspecting the inside of a pipeline based on the received reflected waves, wherein the incident sound wave for inspecting the inside of the pipeline at a point distant from the duct duct opening is a complex and periodic artificial sound. A method for inspecting the inside of a pipeline, characterized by using incident sound waves having characteristics. 2. A sound wave is made incident from a conduit duct opening, and a reflected wave from the inside of the conduit for the incident sound wave is received.
A pipe interior inspection method for inspecting a pipeline interior state based on the received reflected waves, comprising: an incident sound wave for pipeline interior inspection at a distance from a pipeline duct opening; A method for inspecting the inside of a pipeline, comprising using two types of incident sound waves together with the incident sound wave for inspecting the inside of the pipeline. 3. An incident sound wave for inspecting the inside of the conduit at a short distance from the conduit duct opening, and an incident acoustic wave for inspecting the inside of the conduit at a point far from the conduit duct opening are individually and sequentially incident. 3. The method according to claim 2, wherein the reflected sound waveforms for the incident sound waves are separately output, and the state of the inside of the pipeline is inspected for each distance. 4. The pipe according to claim 1, wherein the incident sound wave for inspecting the inside of the pipe at a point far from the pipe duct opening is a sound wave having a dual cycle pulse waveform. Inspection method described in the pipeline. 5. An incident means for receiving a sound wave from a conduit duct opening, a receiving means for receiving a reflected wave from the inside of the conduit for a sound wave incident from the incident means, and a reflected wave received by the receiving means. Inspection means for inspecting the state of the inside of the pipeline based on the above, wherein the incident means is complex and periodic as incident sound waves for inspecting the inside of the pipeline at a distant point from the duct duct opening. A pipe interior inspection device characterized in that an incident sound wave having a characteristic of artificial nature is incident on the inside of the pipeline from a pipeline duct opening. 6. An incident means for injecting a sound wave from a conduit duct opening, a receiving means for receiving a reflected wave from the inside of the conduit for a sound wave incident from the incident means, and a reflected wave received by the receiving means A pipe interior inspection device having inspection means for inspecting the internal state of the pipeline based on: the incident means, the incident sound wave for inspecting the interior of the pipeline at a point far from the pipeline duct opening, and the pipeline duct A pipe interior inspection device characterized in that two types of incident sound waves, an incident sound wave for inspection inside a pipeline at a short distance from the mouth, enter the interior of the pipeline from the pipeline duct opening. 7. The incident means may include an incident sound wave for inspecting the inside of the conduit at a short distance from the conduit duct opening, and an incident acoustic wave for inspecting the inside of the conduit at a distance from the conduit duct opening. The pipeline interior inspection device according to claim 6, wherein the inspection device inspects the interior of the pipeline for each distance. 8. The apparatus according to claim 5, wherein the incident sound wave for inspecting the inside of the pipe at a point far from the pipe duct opening is a sound wave having a dual cycle pulse waveform. Inspection device for pipe interior as described.