Method and apparatus for detecting the position of an abnormal site of a buried pipe

• US 5,544,074 A
• Filed: 01/26/1995
• Issued: 08/06/1996
• Est. Priority Date: 01/16/1992
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kanemaru, Kohji, Taniguchi, Shozo, Enamito, Akihiko, Sato, Yoshiyuki, Suzuki, Takehiko
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): Assouad, Patrick J.
• Application Number:
  US08/378,935
• Time in Patent Office: 558 Days
• Field of Search: 364/508, 73/40.5 A, 73/170.13, 73/861.25, 73/861.26, 73/861.31, 324/329, 324/337, 405/157
• US Class Current: 702/51
• CPC Class Codes: G01M 3/005 using pigs or moles G01M3/246, G01M3/2823 take precedence
• CPC Class Codes: G01M 3/243 for pipes

Abstract

A device for detecting the position of a physical defect on a buried pipe includes a leak-of-fluid signal detector, a number of vibration signal detectors, and a device body and can detect the position of a site of a leak, into the ground, of a fluid running through a fluid pipe buried beneath the ground surface. The device body calculates vibration amplitudes and speeds via associated vibration signal detectors with the use of the outputs of the respective vibration signal detectors, calculates cross-correlation functions of the vibration amplitudes and speeds with the use of the vibration amplitudes and speeds and the output of the leak-of-fluid signal detector, calculates the amplitude intensity for each cross-correlation function, and generates resultant vector data representing the position of the leak-of-fluid site with the use of the vibration intensity.

Claims

1. An apparatus for detecting a position of a leak occurring on a buried pipe containing a fluid and indicating said position on at least one of a display unit and a hard copy output unit, said apparatus comprising:

reference signal detecting means for detecting, as a reference signal, an acoustic signal generated from a physical defect on said buried pipe;

vibration signal detecting means for detecting vibration signals contained in said acoustic signal generated from said physical defect at a plurality of locations on a ground level;

vibration amplitude determining means for determining, based on said vibration signals obtained from said vibration signal detecting means, a vibration amplitude in a predetermined direction defined by a straight line connecting together at least two of said plurality of locations;

vibration energy propagation velocity determining means for determining a vibration energy propagation velocity in said predetermined direction based on said vibration signals obtained by said vibration signal detecting means;

cross-correlation function determining means for determining a cross-correlation function of said vibration amplitude in said predetermined direction based on said reference signal and on said vibration amplitude in said predetermined direction, and for determining a cross-correlation function of said vibration energy propagation velocity in said predetermined direction based on said reference signal and on said vibration energy propagation velocity in said predetermined direction;

vibration intensity determining means for determining a vibration intensity in said predetermined direction based on said cross-correlation function of said vibration amplitude in said predetermined direction and on said cross-correlation function of said vibration energy propagation velocity in said predetermined direction; and

outputting means for outputting, as vector data, said vibration intensity so as to obtain vector data representing a direction of said physical defect on said buried pipe.

2. The apparatus according to claim 1, wherein said vibration signal detecting means is arranged at two of said plurality of locations on said ground level, along a running direction of said buried pipe.

3. The apparatus according to claim 1, wherein:

said vibration signal detecting means detects said vibration signals at a corresponding apex of a predetermined polygon at each of said plurality of locations;

said vibration amplitude determining means determines vibration amplitudes in a plurality of directions defined by a plurality of straight lines connecting together associated apexes of said polygon;

said vibration energy propagation velocity determining means determines vibration energy propagation velocities in said plurality of directions;

said cross-correlation function determining means determines a cross-correlation function of vibration amplitudes in said plurality of directions and a cross-correlation function of vibration energy propagation velocities in said plurality of directions;

said vibration intensity determining means determines vibration intensities in said plurality of directions; and

said outputting means further includes vectorially composing means for vectorially composing said vibration intensities in said plurality of directions and for delivering resultant vector data obtained from said vectorially composing means as an output.

4. The apparatus according to claim 1, wherein said reference signal detecting means is positioned on an exposed pipe portion relative to a ground surface.

5. The apparatus according to claim 1, wherein said reference signal detecting means is comprised of an acceleration sensor.

6. The apparatus according to claim 1, wherein said reference signal detecting means is comprised of a pressure sensor for detecting a pressure of said fluid.

7. The apparatus according to claim 1, further comprising pipe striking means for forcibly striking said buried pipe.

8. The apparatus according to claim 7, wherein said pipe striking means comprises traveling means which travels within said buried pipe and striking means mounted on said traveling means.

9. The apparatus according to claim 1, wherein said vibration signal detecting means comprises first, second, and third vibration signal detecting means placed on corresponding apexes of a given right-angled triangle configuration defined on a ground surface.

10. An apparatus for detecting a position of a leak occurring on a buried pipe containing a fluid and indicating said position on at least one of a display unit and a hard copy output unit, said apparatus comprising:

reference signal detecting means for detecting, as a reference signal, an acoustic signal generated from a physical defect on said buried pipe;

first, second, and third vibration signal detecting means each arranged on a corresponding apex of a right-angled triangle defined on a ground surface;

vibration amplitude determining means, for determining, based on first, second, and third vibration signals obtained from said first, second, and third vibration signal detecting means, respectively, a vibration amplitude in an X-axis direction connecting together first and second apexes of said right-angled triangle and a vibration amplitude in Y-axis direction connecting together first and third apexes of said right-angled triangle;

vibration energy propagation velocity determining means or determining a propagation velocity of vibration energy in said X-axis direction and a propagation velocity of vibration energy in said Y-axis direction on the basis of said first, second, and third vibration signals;

cross-correlation function determining means for determining a cross-correlation function of said vibration amplitude in said X-axis direction based on said reference signal and on said vibration amplitude in said X-axis direction, a cross-correlation function of said vibration amplitude in said Y-axis direction based on said reference signal and on said vibration amplitude in said Y-axis direction, a cross-correlation function of said vibration energy propagation velocity in said X-axis direction based on said reference signal and on said vibration energy propagation velocity in said X-axis direction, and a cross-correlation function of said vibration energy propagation velocity in said Y-axis direction based on said vibration energy propagation velocity in said Y-axis direction;

vibration intensity determining means for determining a vibration intensity in said X-axis direction based on a cross-correlation function of said vibration amplitude in said X-axis direction and on a cross correlation function of said vibration energy propagation velocity in said X-axis direction, and for determining a vibration intensity in said Y-axis direction based on a cross-correlation function of said vibration amplitude in said Y-axis direction and on a cross-correlation function of said vibration energy propagation velocity in said Y-axis direction;

vectorially composing means for vectorially composing said vibration intensity in said X-axis direction and said vibration intensity in said Y-axis direction so as to obtain resultant vector data representing a position of said physical defect; and

output means for delivering said resultant vector data as an output.

11. An apparatus for detecting a position of a leak occurring on a buried pipe containing a fluid and indicating said position on at least one of a display unit and a hard copy output unit, said apparatus comprising:

reference signal detecting means for detecting, as a reference signal, an acoustic signal generated from a physical defect on said buried pipe;

vibration signal detecting means for detecting vibration signals contained in said acoustic signal generated from said physical defect at a plurality of locations on a ground level;

vibration amplitude determining means for determining vibration amplitudes of said vibration signals output from said vibration signal detecting means;

cross-correlation function determining means for determining, based on said vibration signals and said vibration amplitudes, each cross-correlation function of said vibration amplitudes at at least two of said plurality of locations;

vibration energy propagation velocity determining means for determining a vibration energy propagation velocity based on said vibration signals obtained by said vibration signal detecting means;

vibration propagation time difference determining means for determining, as a maximum level difference of respective cross-correlation functions, a vibration propagation time difference in a predetermined direction defined by a straight line connecting together said at least two locations; and

output means for delivering said vibration propagation time difference in said predetermined direction as an output so as to obtain vector data representing a direction of said physical defect on said buried pipe.

12. The apparatus according to claim 11, wherein said vibration signal detecting means is arranged at two of said plurality of locations on a ground level, along a running direction of said buried pipe.

13. The apparatus according to claim 11, wherein:

said vibration signal detecting means is so arranged as to detect vibration signals at corresponding positions of apexes of a predetermined polygon at said plurality of locations;

said vibration amplitude determining means determines vibration amplitudes in a plurality of directions defined by a plurality of straight lines connecting together associated apexes of said polygon;

said vibration energy propagation velocity determining means determines vibration energy propagation velocities in said plurality of directions;

said cross-correlation function determining means determines a cross-correlation function of said vibration amplitudes in said plurality of directions;

said vibration propagation time difference determining means determines vibration propagation time differences in said plurality of directions; and

said output means further includes vectorially composing means for vectorially composing vibration intensities in said plurality of directions and wherein said output means delivers resultant vector data obtained from said vectorially composing means.

14. The apparatus according to claim 11, wherein said vibration propagation time difference determining means comprises:

maximal cross-correlation means for determining a time when said cross-correlation functions of said vibration amplitudes in said plurality of directions become maximal; and

means for determining signal propagation time differences in said plurality of directions based on a time when said cross-correlation functions thus determined by said maximal cross-correlation means become maximal.

15. The apparatus according to claim 11, wherein said reference signal detecting means is exposed on a fluid pipe portion relative to a ground surface.

16. The apparatus according to claim 11, wherein said reference signal detecting means comprises an acceleration sensor.

17. The apparatus according to claim 11, wherein said reference signal detecting means comprises a pressure sensor for detecting a pressure of said fluid.

18. The apparatus according to claim 11, further comprising pipe striking means for forcibly striking said buried pipe.

19. The apparatus according to claim 18, wherein said pipe striking means comprises traveling means which travels within said buried pipe and striking means mounted on said traveling means.

20. The apparatus according to claim 11, wherein said vibration signal detecting means comprises first, second, and third vibration signal detecting means placed at corresponding apexes of a given right-angled triangle.

21. An apparatus for detecting a position of a leak occurring on a buried pipe containing a fluid, and indicating said position on at least one of a display unit and a hard copy output unit, said apparatus comprising:

a plurality of vibration signal detecting means arranged at predetermined intervals on said buried pipe for detecting vibration signals associated with a physical defect on said buried pipe;

vibration amplitude determining means for determining, based on a plurality of said vibration signals obtained from said plurality of vibration signal detecting means, vibration amplitudes in a plurality of predetermined directions defined by a plurality of straight lines connecting together locations of respective vibration signal detecting means;

cross-correlation function determining means for determining cross-correlation functions of vibration amplitudes in said plurality of directions based on said vibration amplitudes in said predetermined directions;

vibration propagation time difference determining means for determining vibration propagation time difference in said plurality of directions based on said cross-correlation functions in said plurality of directions; and

output means for outputting, as vector data, said vibration propagation time difference in said plurality of directions so as to obtain vector data representing a direction of said physical defect on said buried pipe.

22. The apparatus according to claim 21, wherein said vibration propagation time difference determining means comprises:

means for determining a time when said cross-correlation functions of said vibration amplitudes in said plurality of directions become maximal; and

means for determining, based on that determined time, respective signal propagation time differences.

23. The apparatus according to claim 21, further comprising means for forcibly striking said buried pipe.