JPS6367846B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for detecting the location of leaks from piping, such as water leaks, etc., which uses a correlation method to sense and detect locations where water, oil, gas, etc. are leaking from specific positions of piping. It is.

Currently, work to detect water leaks, etc. involves listening directly to the sound of water leaks propagating underground using listening rods and amplifiers inserted into the ground, and predicting the location of water leaks based on the sound volume, tone, etc. However, this method requires a high level of skill and requires nighttime measurements with little noise. Note that it is practically impossible to locate water leaks in pipes installed under obstacles such as buildings, rivers, asphalt roads, etc. In order to overcome these difficulties, measurements of the location of water leakage points, for example, have come to be carried out based on the theory of correlation functions. However, the devices currently in use are capable of accurately measuring the location of water leaks when the propagation velocity of water leak sound in the pipe and the length of the pipe are accurately known. If the propagation velocity changes over time due to corrosion and deterioration of the pipe, the error in the measurement position increases. In addition, after measuring the correlation function, the peak point of the correlation value was read visually and the leak position was obtained by hand calculation using a calculator, etc., which had the drawback of making on-site measurements complicated and resulting in incorrect results. .

In order to solve these drawbacks, the present invention calibrates the pipe length or vibration propagation velocity by assuming that one of the values of the vibration propagation velocity and the pipe length of the piping to be measured is known, and actually measuring the other value. The purpose of this invention is to provide an apparatus for detecting the position of water leakage from piping, which aims to accurately measure the position of water leakage using the measured values, and will be described in detail below with reference to the drawings.

The drawing is a schematic diagram showing an embodiment of the present invention. First, as shown in the figure, a vibration detection sensor is installed at an appropriate distance in the longitudinal axis direction of the pipe to be measured 1, where water leakage, etc., is to be detected using the locations of fire hydrants, water stop valves, water meters, etc. 2 and sensor 3 are each fixedly attached. 2 and 3 correspond to first and second vibration detection elements that detect the first and second sensing signals. In this state, impact is applied to the pipe where sensor 2 is installed with a hammer. Then, vibrations are transmitted to sensor 2 without any time delay, and vibrations are transmitted to sensor 3 with a certain time delay. Sensing signal outputs from each sensor are input to the corresponding amplifiers 4 and 5 and amplified. The first sensing signal from the amplifier 4 is input to a comparator 8, and when it exceeds a preset reference voltage, a pulse is output as a trigger signal.
On the other hand, the second sensing signal from the amplifier 5 is input to the A/D converter 7, converted into a digital signal by a sampling pulse cycle at fixed time intervals, and outputted. If the correlation/wave memory 10 is set to wave memory operation by the control circuit 9, digital data from the A/D converter 7 is sequentially recorded in the memory by a trigger pulse from the comparator 8. When the recording of the specified number of data, that is, the recording of the n-th data from the first data based on the trigger signal to the maximum amplitude value of the second sensing signal is completed, the program stored in the ROM 11 Accordingly, the CPU 12 detects the number N of points from the start to the peak position of the recording data, and the delay time T _D from sensor 2 to sensor 3 is determined from the sampling period T _S as T _D =T _S ×N. Specifically, T _D is displayed on the CRT 13. Therefore, if the pipe propagation velocity V is known, the pipe length L is L=
If the pipe _length L is known, the pipe propagation velocity V is determined as V=L/T _D , and is displayed on the CRT 13 as the calibration value of the parameter necessary for calculating the leak location. . Next, the control circuit 9
If the correlation/wave memory 10 is set to a correlation calculation operation (that is, an operation that performs multiplication and integration using time delay as a parameter), for example, water leakage sound detected by the sensors 2 and 3 will be detected by the A/D converter 6, A A correlation function is calculated by a correlation/wave memory 10 via a /D converter 7. When the calculation is completed, the peak point of the correlation value is automatically detected by the CPU 12 according to the program in the ROM 11, and the difference in arrival time of the vibration signal generated from the water leak point to the sensors 2 and 3 is determined and displayed on the CRT 13.
Next, set the parameters such as pipe type, pipe diameter, pipe length, and pipe structure that are set in ROM11 in advance.
According to the calculation program stored in the ROM 11, the CPU 12 displays the distance from the reference point (for example, the sensor 2) to the water leakage point on the CRT 13. In this case, it may be output to the printer 14.

As explained above, the pipe length or pipe propagation velocity, which are important parameters necessary for calculating the leak location, are calibrated using actual measured values, and based on these calibration values, the accuracy can be improved because they match the actual condition of the pipe at the time of measurement. It has the advantage of being able to perform good position calculations. In addition, since measurements can be performed automatically from the start of correlation calculation to the determination of the water leak location, accurate results can be easily obtained.

[Brief explanation of drawings]

The figure is a schematic diagram showing an embodiment of the present invention. 1...Pipe to be measured, 2...Sensor, 3...Sensor, 4...
Amplifier, 5...Amplifier, 6...A/D converter, 7...
A/D converter, 8... Comparator, 9... Control circuit, 10... Correlation/wave memory circuit, 11...
ROM, 12...CPU, 13...CRT, 14...Printer.

Claims (1)

[Claims] 1. A first vibration detection element that detects a first sensing signal corresponding to the vibration caused by a blow applied to a specific position of the tube to be measured, and a certain delay time from the point of occurrence of the vibration caused by the blow. and a second vibration detection element for detecting a second sensing signal corresponding to vibration at a specific position in the longitudinal axis direction of the pipe to be measured that occurs at a later point in time, respectively, and a comparator that outputs a trigger signal only when the first sensing signal exceeds the reference voltage by adding the first sensing signal and a preset reference voltage; and a maximum amplitude value obtained from the second vibration detection element. an A/D converter that outputs digital data that is sequentially converted into a digital signal by a sampling pulse cycle at fixed time intervals to which a second sensing signal is added;
a correlation/wave memory in which each digital signal of the digital data is sequentially accumulated by the trigger signal and records data from the first data to the n-th data corresponding to the maximum amplitude value based on the trigger signal; The CPU detects the number N of recorded data from the first to the nth, and detects the amplitude delay time T _D from the first vibration detection element to the second vibration detection element and the sampling pulse period. T _S and ga
Based on the pipe length or vibration propagation velocity, which has the relationship T _D = T _S ×N, and has a calibration value based on the known value of vibration propagation velocity or pipe length, based on the actual situation at the time of measurement. A device for detecting the position of leakage from piping, such as water leakage.