JP2005283169A - Leakage water sound detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leakage water sound detection device capable of capturing effectively an extremely feeble leakage water sound even in the case where a water conduit is a large-diameter conduit or a resin conduit. <P>SOLUTION: This leakage water sound detection device 1 is constituted of a sound collection part 2, a body part 3, a connection part 4 and a joint part 5. As for the sound collection part 2, a peripheral wall part is gradually enlarged toward the downside, and the lower end is an open end. As for the body part 3, a piezoelectric element 7 is disposed on the lower end of a casing 6, and the upper end of the sound collection part 2 is fixed on the lower end of the casing 6. As for the connection part 4, a buffer member 12 comprising an elastic material is interposed between a lower casing 11 and an upper casing 13. As for the joint part 5, the connection part 4 is mounted on a proper spot of the water conduit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a water leakage sound detection device used for detecting a water leakage position in a water pipe buried in the ground.

  In recent years, as a method of detecting a water leak position in a water pipe buried in the ground, as shown in FIG. 8, a water pipe is detected by a water leak sound detection device 51, 51 attached to a fire hydrant or the like installed in the water pipe. The leaking sound propagating through the road is detected, and the detected leaking sound signal is amplified and transmitted by the leaking sound detection device slave units 52, 52. Based on the transmitted leaking sound signal, the leakage detection device master unit 53 A correlation type water leak detection method for detecting a water leak position in a water pipe by analyzing a correlation waveform is adopted.

  And as the said water leak sound detection apparatus 51, the underwater microphone or the acceleration pick-up is used (refer patent document 1 and patent document 2).

JP-A-11-72409

Japanese Patent Laid-Open No. 11-117356

However, when the water pipe is a large-diameter pipe, there are few places to install the underwater microphone or the accelerometer, and it must be installed at a point away from the water leakage position. Further, when the water pipe is a resin pipe, the water leakage sound is greatly attenuated when propagating through the water pipe as compared with the metal pipe.
Therefore, the leaked sound that can be detected at the position where the underwater microphone or the like is attached is extremely weak, and the conventional underwater microphone or the like cannot effectively capture the leaked sound.

  The present invention has been made in view of such conventional problems, and even if the water pipe line is a large-diameter pipe line or a resin pipe line, an extremely weak leak sound is effective. An object of the present invention is to provide a water leakage sound detection device that can be captured.

  In order to achieve the above object, the water leakage sound detection apparatus of the present invention has a sound collecting portion having a peripheral wall portion that is gradually expanded in diameter downward and having a lower end portion as an open end, and a piezoelectric element disposed at the lower end portion in the housing. And a connection part in which a buffer member made of an elastic material is interposed between the lower casing and the upper casing, and the connection It is characterized by comprising a joint part that attaches the part to an appropriate part of the water pipe.

Hereinafter, a water leakage sound detection apparatus of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the water leakage sound detection apparatus 1 according to the present invention includes a sound collection unit 2, a main body unit 3, a connection unit 4, and a joint unit 5.

  The sound collecting part 2 is made of a metal material such as brass or stainless steel, and the peripheral wall part is thin and gradually increases in diameter downward, and has a substantially conical shape. The lower end part is an open end and the upper end part is reduced. As the diameter portion 2a.

The main body 3 is provided with a piezoelectric element 7 at a lower end in a housing 6 made of a metal material such as brass or stainless steel, and an electronic circuit board 8 is provided at an intermediate part. And the electronic circuit board 8 are connected by an electric wire 9.
Here, an impedance conversion circuit is configured on the electronic circuit board 8 to reduce the impedance of the output signal from the piezoelectric element 7. When the output signal is in a high impedance state, it is easily affected by external noise, so the output signal is reduced in impedance to reduce the influence of external noise. In the present embodiment, the impedance of the output signal is set to be 100Ω or less at the output end of the impedance conversion circuit.
Moreover, the lower end part of the housing | casing 6 is made into the protrusion part 6a reduced in diameter. And the diameter-reduced part 2a which is the upper end part of the said sound collection part 2 is adhering to the protrusion part 6a with the fastening members 10, such as metal bolts.

The connection part 4 is comprised from the lower housing | casing 11, the buffer member 12, and the upper housing | casing 13, and the lower housing | casing 11 and the upper housing | casing 13 consist of metal materials, such as a brass and stainless steel.
The buffer member 12 is formed as a lump made of an elastic material such as low-rebound rubber, and is interposed between the lower housing 11 and the upper housing 13.
Here, the low resilience rubber is a rubber having a rebound resilience as extremely small as 1 to 3% and excellent in vibration absorption, sound absorption, and impact resistance.
An electric cable 14 is inserted into the lower casing 11, the buffer member 12 and the upper casing 13, and the electric cable 14 is connected to the electronic circuit board 8.

  The joint portion 5 employs a so-called Machino type pipe joint, the lower portion 15 is made of an elastic material, the upper portion 16 is made of a metal material such as aluminum, and the upper end portion is a fastening member 17 such as a nut. Is arranged.

The water leakage sound detection apparatus 1 according to the present invention has the above-described configuration and exhibits the following operations and effects.
First, as shown in FIG. 3, the water leakage sound detection device 1 can be attached to the upper end portion 21 a of the fire hydrant 21 installed at an appropriate location of the water pipe by the joint portion 5.

  At the time of installation, as shown in FIG. 3, the water leakage sound that has propagated through the water pipe reaches the upper end portion 21 a of the fire hydrant 21. Then, it is captured by the open end of the sound collecting unit 2 of the water leakage sound detection device 1.

  Since the peripheral wall portion of the sound collecting portion 2 has a substantially conical shape whose diameter is gradually expanded downward, a weak water leakage sound can be sufficiently concentrated, and the water leakage sound is reduced in the reduced diameter portion 2a at the upper end portion. The vibration energy of becomes large.

  And since the lower end part of the housing | casing 6 of the main-body part 3 is made into the protrusion part 6a reduced in diameter, and the piezoelectric element 7 is arrange | positioned in the lower end part in the housing | casing 6, the vibration energy of a water leak sound is It is transmitted to the piezoelectric element 7 without decreasing.

On the other hand, there are noises propagating through the water pipes, noises transmitting in the air, etc. around the leak sound detection device 1, but these noises are caused by elastic materials such as low-resilience rubber. The vibration energy is greatly attenuated by being absorbed by the buffer member 12.
Therefore, the S / N ratio between the water leakage sound and the external noise can be greatly improved.

Further, in the electronic circuit board 8 disposed in the main body 3, the impedance of the detection signal is lowered by an impedance conversion circuit, and an electrical external noise countermeasure is taken to minimize the influence of the external noise.
In this respect, the S / N ratio between the water leakage sound and the external noise can be greatly improved.

  Next, the detection effect of the water leak sound by the water leak sound detection apparatus 1 of the present invention will be described based on a specific experimental example.

[Experimental Example 1]
The water leakage sound detection device 1 of the present invention and the conventional water leakage sound detection device were mounted on the test jig 31 to confirm the output level of the simulated water leakage sound.
Here, as the conventional water leakage sound detection device, a device obtained by removing the sound collecting unit 2 from the water leakage sound detection device 1 of the present invention was used.
As shown in FIG. 4, the test jig 31 uses a U-shaped metal tube, and the water leak sound detection device 1 of the present invention or the conventional water leak sound detection device is attached to one end of the metal tube. A vibration generator 32 was attached to the other end.
Further, an FFT analyzer (not shown) was connected to the water leakage sound detecting device via a cord 33, and an oscillator 36, a signal generating device 37, and a power source 38 were connected to the vibration generating device 34 via a cord 35.

A simulation signal having a predetermined frequency was generated by the signal generator 37, and a vibration sound was generated at the other end of the test jig 31 by the vibration generator 34. The propagation sound was detected at one end of the test jig 31 by a water leakage sound detection device, and analyzed and output by an FFT analyzer.
The output result was as shown in FIG. From this, it has been found that the output level of the leaked sound detection device 1 of the present invention is significantly improved over a wide frequency band as compared with the conventional leaked sound detection device.

[Experiment 2]
The water leakage sound detection device 1 of the present invention and the conventional water leakage sound detection device were attached to a fire hydrant 42 installed in a metal pipe 41 embedded in the test course, and the output level of the water leakage sound was confirmed.
Here, as a conventional water leakage sound detection device, a device obtained by removing the sound collection unit 2 from the water leakage sound detection device 1 of the present invention was used, as in Experimental Example 1.
As shown in FIG. 6, in the metal pipe 41 embedded in the test course, a fire hydrant 42 was installed at an appropriate location, and a small hole 43 was drilled at an appropriate location.
In addition, the water leakage sound detection device 1 of the present invention or the conventional water leakage sound detection device was attached to the upper end portion of the fire hydrant 42, and an FFT analyzer 45 was connected to the water leakage sound detection device via a cord 44.

A predetermined flow rate of water was circulated in the metal pipe 41, water was leaked from the small holes 43 formed in the metal pipe 41, and a water leakage sound was actually generated. The propagation sound was detected at the upper end of the fire hydrant 42 by a water leakage sound detection device, and analyzed and output by the FFT analyzer 45.
The output result was as shown in FIG. From this, it has been found that the output level of the water leak sound detection device 1 of the present invention is significantly improved particularly in the low frequency band as compared with the conventional water leak sound detection device.

It is a front view of the water leak sound detecting device of the present invention. It is the sectional view on the AA line of the water leak sound detection apparatus of FIG. It is AA sectional view taken on the line explaining the effect | action and effect of the water leak sound detection apparatus of FIG. It is explanatory drawing which shows the test method which equips a test jig with a water leak sound detection apparatus, and confirms the output level of a simulated water leak sound. It is a figure which shows the difference in the output level by the difference in a water leak sound detection apparatus. It is explanatory drawing which shows the test method which attaches the water leak sound detection apparatus to the fire hydrant installed in the metal piping, and confirms the output level of a water leak sound. It is a figure which shows the difference in the output level by the difference in a water leak sound detection apparatus. It is explanatory drawing of a correlation type | formula water leak detection method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water leakage sound detection apparatus 2 Sound collecting part 3 Main body part 4 Connection part 5 Joint part 6 Case 7 Piezoelectric element 8 Electronic circuit board 11 Lower case 12 Buffer member 13 Upper case

Claims (2)

The peripheral wall portion is gradually expanded in diameter downward, a sound collecting portion having an open end at the lower end portion, a piezoelectric element is disposed at the lower end portion in the housing, and an upper end portion of the sound collecting portion at the lower end portion of the housing A main body portion, a connection portion in which a buffer member made of an elastic material is interposed between the lower housing and the upper housing, and a joint portion that attaches the connection portion to an appropriate portion of the water pipe. A water leakage sound detection device characterized by comprising. The water leakage sound detection device according to claim 1, wherein an electronic circuit board configured with an impedance conversion circuit that lowers an impedance of an output signal from the piezoelectric element is disposed in the housing of the main body.

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