JP3482086B2 - Reflection Signal Judgment Method in Acoustic Line Inspection System - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of determining a reflection signal in a pipe in a system for investigating the inside of a pipe by using sound waves.

[0002]

2. Description of the Related Art Pipes such as gas pipes and water pipes buried in the ground may be corroded and deteriorated by laying for a long period of time or damaged by external force. Therefore, it is necessary to investigate the inside of the pipe and take repair measures by repair work. Conventionally, as one of the systems used for investigating the inside of this kind of pipeline, there is a system in which a device such as a camera or a fiberscope is inserted into the pipeline so that the state inside the pipeline can be directly viewed. However, the method of inserting such a device requires additional equipment such as a cable to be inserted into the pipeline and insertion work, which may result in a large amount of work and equipment for investigation. Further, if there is a breakage point or a branch point in the middle of the pipeline, it is difficult to guide the equipment at that location, which causes a problem that the entire pipeline cannot be accurately investigated. Therefore, instead of such a method, a system is proposed in which sound waves are sent from the end of the pipeline and the situation of the inside of the pipeline is checked simply by observing the reflection status of the sound waves from both ends or one end of the pipeline. (For example, JP-A-61-29757,
JP-A-61-2202158). In the above-mentioned publication, a sounding means and a sound collecting means are arranged at the end of the pipe, and it is detected that a sound wave sent from the sounding means is reflected at a cross-sectional area changing portion generated in the pipe, A technique capable of observing the position up to the changed portion is disclosed. Such a technique can not only detect the cross-sectional area changing portion in the pipe but also investigate the position of the joint portion or the like installed in the pipe by observing the generation position of the reflected sound wave.

[0003]

However, when the inside of the duct is investigated using sound waves, the time taken for the sound waves sent from the sounding means to be collected as reflected sound waves by the transmission path differs. For example, if the ends of the conduit are located at both ends across the branch, the sound wave sent from one of the ends is the reflected sound wave reflected from the end of the branch pipe, Although reflected sound waves reflected from one end other than one of the ends may be considered, in reality, the reflection reflected from the end of the branch pipe via the branch to the end other than one of the ends of the pipeline. There are also sound waves. Therefore, on the received data of the reflected sound wave, the sound wave sent from one of the end portions of the conduit is reflected at the end portion of the branch pipe through the branch portion, and the reflected sound wave is passed through the branch portion. There is a case where a received signal collected after being reflected at an end other than one of the ends of the pipeline may be obtained, and it is erroneously determined that there is a reflection source at the position indexed from the reception timing. There is a risk that

FIG. 5 is a diagram for explaining a state in which a reflected signal is obtained on the received data relating to the reflected sound wave even though there is no reflecting source in the actual conduit, and the upper part of FIG. Shows the piping route, and the lower diagram in FIG. 5 shows the reception timing of the reflected sound waves in the upper piping route.
In the piping route of FIG. 5, one of the ends of the pipeline P1 (A)
A speaker 1 which is a sound producing means and a microphone 2 which is a sound collecting means are arranged in the branch pipe P through the branch portion (D).
2 is connected, and when the end (C) of the branch pipe P2 and the end (B) other than one (A) of the ends of the conduit P1 are opened, the sound wave reception data is observed. It will be as shown in the bottom row. Note that the numbers shown in the upper part of FIG. 5 indicate the distances of the respective pipelines with the branch portion (D) as a boundary, and are associated with the reception timing of the reflected sound waves.

In FIG. 5, the received signal of the reflected sound wave corresponds to an end portion other than the branch portion (D) and one end portion (A) of the pipe path P1 in accordance with the order of arrival of the sound wave.
The end portion (C) and the other end portion (B) of the pipeline P1 are obtained in this order. In addition to such a received signal, from the end portion (C) of the branch pipe P2 to the end portion of the pipeline P1. The reception signal (H) of the reflected sound wave reflected and collected by (B) is obtained at the reception timing corresponding to the distance of the sound wave transmission path. Therefore, there is a possibility that the reflection source is erroneously determined to be present at a position at a distance calculated from the reception timing of the reflection signal (H).

In view of the above-mentioned problems in the conventional sound wave type pipe line survey system, an object of the present invention is to make it possible to judge a false signal obtained at the reception timing and to judge the reflection source in the pipe line. An object of the present invention is to provide a method for determining a reflection signal in a pipe in a sound wave type pipe survey system capable of preventing an accidental error.

[0007]

In order to achieve this object, the invention according to claim 1 provides a sounding means for transmitting a pulsed sound wave into one of the ends of the pipe, and the pipe. The time and sound velocity value from the time when the pulsed sound wave is transmitted to the time when the pulsed sound wave is collected by using a sound collecting means that collects the pulsed sound wave reflected in the pipe at one of the ends of the path. In the sonic type pipe survey system for investigating the inside of the duct from the first step of transmitting a sound wave from one of the ends and storing reception data regarding the reflected sound wave, and a step other than one of the ends. A sound wave is transmitted from one of the end portions in a state in which the end portion is set to either the open / closed state different from the open / closed state in the first step and the reflection condition is changed, and reception data regarding the reflected sound wave is stored. Second step, and the above first and second steps
And a third step of comparing the received data relating to the reflected sound waves obtained in the step of, in the third step, the received signal whose phase is inverted first appears on the reception timing. The received signal of the inverted phase is determined as a signal from one of the end portions whose reflection conditions have been changed in the first and second steps, and the received signal of the inverted phase that appears next is determined as a false signal. It is characterized by doing.

According to a second aspect of the present invention, a sounding means for sending a pulsed sound wave into one of the end portions of the conduit into the conduit,
Time and sound velocity from the time when the pulsed sound wave is transmitted to the time when the pulsed sound wave is collected by using a sound collecting means that collects the pulsed sound wave reflected in the conduit at one of the ends of the conduit. In a sound wave type pipe survey system for investigating the inside of a pipe line from a value, a first step of transmitting a sound wave from one of the end portions and storing reception data regarding the reflected sound wave, and one of the end portions. A second step of setting a non-reflective state as a reflection condition of the other end, transmitting a sound wave from one of the end parts, and storing reception data regarding the reflected sound wave; and the first and second steps And a third step of comparing the received data relating to the reflected sound waves obtained in step 3, in the third step, a reflection state different from that of the first received data on the received data obtained in the second step. And the different reflection states on the received data are small. Both when it is observed two locations, the received signal of the second and subsequent is characterized by determining as false signal.

[0009]

According to the first aspect of the invention, of the received signals appearing at the reception timing, the first appearing inverted phase received signal is set as the received signal from the end portion where the reflection condition is changed, and then appears. By determining the received signal of the inverted phase as a false signal, it is possible to distinguish between the reflected sound wave from the regular reflection source and the reflected sound wave that is not.

According to the second aspect of the invention, among the received signals appearing at the reception timing, changes in the reflection state of the sound wave transmitted from one of the ends are compared, and different reflection states are shown in the reception data. 2 if at least 2 sites are observed
By determining the received signals after the th th as false signals, it is possible to distinguish between the reflected sound waves from the regular reflection source and the reflected sound waves that are not.

[0011]

The present invention will be described below with reference to illustrated embodiments.
FIG. 1 is a schematic diagram showing a schematic configuration of a sound wave type duct survey system used in a reflection signal discrimination method according to the present invention. In FIG. 1, a sound wave type duct survey device 10 is provided in the sound wave type duct survey system. This sonic pipe survey device 10 is used
Is provided with at least a sound producing unit 11, a sound collecting unit 12, a CPU 13 which is a control unit, a display 14, a D / A converter 15, amplifiers 16 and 17, and an A / D converter 18. In addition to the above-mentioned members, the sound wave type pipe survey apparatus 10 may also use a sound velocity correction means for changing the sound velocity value that changes depending on the temperature inside the pipe, the type of gas inside the pipe, and the temperature. The display 14 is a CRT monitor or L
ED display boards, and devices such as liquid crystal displays, plasma displays, and electroluminescence that can visually observe the reception timing of reflected sound waves are used.

The determination of the multiple reflection signal using the acoustic wave type channel survey apparatus 10 is executed based on the principle described with reference to FIGS. FIG. 2 shows the reception timing of the reflected sound waves in the pipeline, assuming the same configuration as the pipeline shown in FIG. First, the sound wave transmitted from the sounding means 11 and reflected by the reflection source is the end portion (B) of the conduit P1 corresponding to the end portion other than one (A) of the end portions of the conduit P1 in which it is arranged. ) Is open and the end (C) of the branch pipe P2 is open, the respective end (B),
When the phase is inverted at (C) and the ends (B) and (C) are closed, the phase does not change at the ends (B) and (C). In addition, the sound wave sent from the sounding means 11 and reflected by the reflection source corresponds to the end (C) of the branch pipe P2 other than one end (A) of the pipe P1, and the end of the pipe P1. Even when the light is reflected in the order of the end portion (B), the received signals can be obtained at the same time with the same phase relationship as above.

FIG. 2 shows the other end (B) of the conduit P1 and the end of the branch pipe P2 (corresponding to an end other than one (A) of the ends of the conduit P1 shown in FIG. C) is the reception timing in the case where it is opened, and in the figure, the phase of the reflected sound wave at the reception timing is inverted at the branch portion D,
Further, at the end portion (B) of the branch pipe P2, the phase is the same as that at the branch portion D because it is inverted with respect to the phase at the time of being sent.
Since the other end (B) of the conduit P1 is open at the end (B) other than one of the ends (A) of the conduit P1,
The phase of the reflected sound wave is inverted with respect to the transmitted sound wave. In the received signal indicated by reference character H ′ in FIG. 2, the sound wave reflected at the end (C) of the branch pipe P2 is transmitted to the other end (B) of the conduit P1 and reflected at the end (B). The received signal H'of the reflected sound wave obtained in this case is
At the branch portion (D), the phase becomes inverted with respect to the transmitted sound wave, and after the phase is inverted again at the end portion (C) of the branch pipe P2, the pipe P
Since the phase is inverted again at the end portion 1 (B) of 1, the phase becomes the same as the transmitted sound wave.

On the other hand, the reflection obtained when the reflection state of the sound wave is changed by closing the end (C) of the branch pipe P2, which is the end other than one (A) of the ends of the conduit P1. The sound wave reception timing is as shown in FIG. That is, the phase of the reflected sound wave at the branch portion D is the same as that shown in FIG. 2, but the phase of the reflected sound wave at the end portion (C) of the branch pipe P2 is shown in FIG.
Reverses the case shown in. Further, the phase of the reflected sound wave from the end (B) other than one (A) of the ends of the conduit P1 is the same as that shown in FIG. In FIG. 3, the received signal H ′ shown in FIG. 2 has the end (C) of the branch pipe P2 closed and thus the end (B) of the conduit P1 without changing the phase of the reflected sound wave. , Reference numeral H1 ′ in FIG.
Invert as shown in. Therefore, on the reception timing,
Of the received signals in which the phase of the reflected sound wave is inverted before and after the change of the reflection condition, the first received inverted phase received signal (indicated by a symbol C in the figure) is
It can be assumed that it is the received signal from the end portion where the reflection condition is changed, in this case, the end portion (C) of the branch pipe P2, and the received signal of the inverted phase that appears next (Fig. Among them, the signal indicated by the symbol H1 ′) can be regarded as a false signal.

In this embodiment, the following steps are executed based on the above principle. (1) First step In this step, a sound wave is sent from the sounding means 11 of the sound wave type pipe survey apparatus 10 arranged at one end (A) of the pipe line P1, and received data relating to the reflected sound wave. Memorize This reception data is the reception timing data shown in FIG. (2) Second step In this step, the reflection condition of the end portion other than one (A) of the end portions of the conduit, that is, the end portion (C) of the branch pipe P2 in this embodiment, is changed to a sonic type. A sound wave is transmitted from the sounding means 11 of the pipe survey device 10, and the received data regarding the reflected sound wave is stored.
This reception data is the reception timing data shown in FIG. (3) Third step In this step, the reception data obtained in the first and second steps are compared. In this comparison, based on the principle described with reference to FIG. 2 and FIG.
The first received signal is the end where the reflection condition is changed, that is,
It is determined that the received signal is from the end (C) of the branch pipe P2, and the received signal of the next inverted phase is determined as a false signal.
Thus, if a false signal is found, the distance obtained from the reception timing of the received signal can be ignored, so there is no risk of erroneously determining that there is a reflection source at the position of that distance.

Next, the invention according to claim 2 will be described. FIG. 4 shows the reception timing of reflected sound waves for explaining the embodiment of the invention described in claim 2. The reflected sound waves shown in FIG. 4 are intended for the piping route shown in FIG. The reflection condition at the end portion (C) of the branch pipe P2 corresponding to the end portion other than one (A) of the end portions of P1 is changed to a reflective state and a non-reflective state. . Branch pipe P2
As a reflection condition at the end portion (C), a sound absorbing material such as glass wool, a silencer, or a sounding means 11 of the sound wave type pipe survey device 10 is not shown as a structure for obtaining a non-reflection state. There is used an active noise controller or the like for arranging a sound generating means for transmitting a sound wave having a phase opposite to that of the generated sound wave and canceling the sound wave from the sound generating means 11. When the reflection condition at the end (C) of the branch pipe P2 is set to the non-reflection state, there is no reflected sound wave from the end (C) of the branch pipe P2, and the reception signal is obtained on the reception timing. I can't.
Therefore, when the reception signal from the end (C) of the branch pipe P2 is obtained on the reception data regarding the reflected sound wave of the sound wave sent from the sounding means 11, and the reflection condition at the end (C) is changed. The case where no received signal is obtained by doing so (in FIG. 4, the state where there is no received signal is shown in FIG. 3 in which the reception timing of the received signal is matched and only the time axis is shown). When observed in at least two places, the second and subsequent received signals can be regarded as false signals, as in the case described with reference to FIGS. 2 and 3.

In this embodiment, the following steps are executed based on the above principle. (1 ') First step This step is the same as the first step described in the previous embodiment, so description thereof will be omitted. (2 ') Second step In this step, the reflection condition of the end (C) of the branch pipe P2 corresponding to the end other than one (A) of the ends of the conduit P1 is changed from the reflection state to the non-reflection state. The sound generator 11 transmits a sound wave, and the received data regarding the reflected sound wave is stored. The reception data in this case is the reception timing data shown in FIG. In FIG. 4, the received signal indicated by the broken line is the first
Means the received signal regarding the reflected sound wave obtained in the step of
It does not appear in the second step. (3 ') Third step In this step, the reception data obtained in the first and second steps are compared. In this comparison, different reflection states are observed between the reception data obtained in the first step and the reception data obtained in the second step, and the reflection state and the non-reflection state are present in at least two places on the reception data. If there is a change in, the second and subsequent reflected signals are determined as false signals. Thus, if a false signal is found, the distance obtained from the reception timing of the received signal can be ignored, so there is no risk of erroneously determining that there is a reflection source at the position of that distance.

[0018]

According to the first aspect of the invention, of the received signals appearing at the reception timing, the first appearing inverted-phase received signal is the received signal from the end whose reflection condition is changed, By determining the received signal of the inverted phase that appears next as a false signal, it is possible to distinguish between the reflected sound wave from the regular reflection source and the reflected sound wave that is not so. Since the distance obtained from the signal reception timing can be ignored, it is possible to eliminate the possibility of erroneously determining that the reflection source exists at the position of the distance.

According to the second aspect of the invention, among the received signals appearing at the reception timing, the change in the reflection state of the sound wave transmitted from one of the ends is compared, and the different reflection states indicate the received data. When at least two locations are observed above, the second and subsequent received signals are determined as false signals, so that it is possible to distinguish between reflected sound waves from a normal reflection source and reflected sound waves that are not, so that false signals If it is found that the distance obtained from the reception timing of the received signal can be ignored, it is possible to eliminate the possibility of erroneously determining that the reflection source exists at the position of the distance.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a configuration of a main part of an apparatus used in a reflected signal determination method according to the present invention.

FIG. 2 is a reception timing chart of reflected sound waves for explaining the principle used in the embodiment of the invention described in claim 1.

FIG. 3 is a reception timing chart showing another mode of reflected sound waves for explaining the principle used in the embodiment of the invention described in claim 1.

FIG. 4 is a reception timing chart of reflected sound waves for explaining the principle used in the embodiment of the invention described in claim 2.

5A and 5B are a schematic diagram of a pipeline and a reception timing chart of reflected sound waves obtained in the pipeline for explaining a conventional acoustic wave pipeline survey system.

[Explanation of symbols]

10 Sonic pipe survey equipment 11 Pronunciation means 12 Sound collecting means P1 pipeline P2 branch pipe One of the ends of the A pipeline B, C Ends other than one of the ends of the pipeline

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01B 17/00-17/08 G01N 29/00-29/28 G01S 1/72-1/82 G01S 3 / 80-3/86 G01S 5/18-5/30 G01S 7/52-7/64 G01S 15/00-15/96

Claims (2)

(57) [Claims] 1. A sounding means for transmitting a pulsed sound wave into one of the ends of the conduit, and a pulsed sound wave reflected in the conduit at one of the ends of the conduit. In the sonic type pipe survey system for investigating the inside of the pipeline from the time from the time when the pulsed sound wave is transmitted to the time when the sound is collected and the sound velocity value using the sound collecting means for collecting the A first step of transmitting a sound wave from one and storing reception data related to the reflected sound wave; and an open / closed state other than the open / closed state of the first step other than one of the end portions The second step of transmitting a sound wave from one of the end portions with the reflection condition changed and storing the reception data regarding the reflected sound wave, and the first and second steps. And a third step of comparing received data regarding reflected sound waves, In the third step, of the received signals whose phases are inverted, the received signal of the inverted phase that first appears on the reception timing is treated as one of the end portions whose reflection conditions have been changed in the first and second steps. A method for determining a reflected signal in a sound wave channel survey system, characterized in that a received signal of an inverted phase that appears next is determined as a false signal as a signal from other than one. 2. A sounding means for transmitting a pulsed sound wave from one of the ends of the conduit into the conduit, and a pulsed sound wave reflected in the conduit at one of the ends of the conduit. In the sonic type pipe survey system for investigating the inside of the pipeline from the time from the time when the pulsed sound wave is transmitted to the time when the sound is collected and the sound velocity value using the sound collecting means for collecting the The first step of transmitting a sound wave from one and storing the reception data relating to the reflected sound wave, and setting one of the above end parts by setting a non-reflective state as the reflection condition of the end part other than one of the above end parts. A second step of transmitting a sound wave from the first and storing reception data relating to the reflected sound wave, and a third step of comparing the reception data relating to the reflected sound wave obtained in the first and second steps, In the third step, on the received data obtained in the second step, Compared with the above-mentioned first received data and different reflection states, when at least two different reflection states are observed on the received data, the second and subsequent received signals are determined as false signals. Reflection signal judgment method in pipeline survey system.