JPS63108240A - Discriminating device for fault point direction - Google Patents

Abstract

PURPOSE:To allow one device to discriminate in which direction a water leak position of a city water tube made of various materials is, by providing two sensors which detect the vibration of the tube wall, varying the distance between the sensors, and discriminating the direction of the water leak position which is a signal source. CONSTITUTION:Tube wall vibrations which are caused by leak water are detected by the two sensors 1 and 2 and a signal generated by delaying the output signal of the 2nd sensor 2 fitted linearly movably to the 1st reference sensor 1 and the output signal of the 1st reference sensor 1 are inputted to a phase difference zero detecting circuit 5 which detects their position difference being zero. The 2nd sensor 2 is shifted in position matching with the propagation speed of the vibrations and the direction of the water leak position is discriminated from where the phase difference becomes zero. Consequently, the position of the movable sensor is adjusted according to the kind of the tube and the sensor is only placed on the tube wall while changed in direction, thereby easily knowing the direction of the water leak position under the ground.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Technical Field of the Invention) The present invention relates to a failure point direction determining device for detecting the position of a leak from a gas, powder, or liquid transport pipe.

(Prior Art) In order to make the explanation concrete, underground water leakage from a water pipe will be taken as an example below. Water leak detection methods include the acoustic method that relies on human hearing, the correlation method that calculates the correlation between signals from two distant points and estimates the position from the signal phase difference and propagation speed, the sound of water usage, and the urban A time-integration water leak detection device (Japanese Unexamined Patent Publication No. 6
0-209117) is known. In the acoustic method, experts estimate the location of water leaks from the ground based on the strength and tone of the sound, but the estimated locations vary widely. The correlation method is a scientific method, but since the propagation speed of feedback in a pipe varies depending on the pipe material, it is required that the pipe material and pipe length be accurately known. Furthermore, there is a joint part that exists in the middle of the pipe.

Due to variations in propagation speed due to the influence of gate valves, fire hydrant branch points, etc., an error in position estimation occurs of approximately ±1 m. In addition, the time-integration type water leak detection device has a circumference of several tens of meters.
The purpose of this system is to automatically detect leaks within a certain area, and it is not possible to pinpoint the location of the leak.As the location error is unavoidable, leaks may not be discovered even when excavating buried pipes. As is often the case, conventionally there was no equipment available to determine the location of water leaks at close range, so skilled workers had to repeatedly conduct trial excavations based on the sound they heard from exposed pipes. In addition, there is a water leakage detection device with a direction determination function proposed by the inventor (Japanese Utility Model Application Publication No. 120228/1983), which was originally designed to detect water leakage in pipes of known pipe material. It is intended to be installed permanently,
It cannot be applied to pipes made of arbitrary materials.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned problems.
To provide a failure point direction determination device capable of determining in which direction the leakage position of water pipes made of various materials is located using a single device.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides two sensors for detecting the vibration of the pipe wall, and by making the distance between the sensors variable, the direction of the water leakage site, which is the signal source, is determined. be.

(Function) The present invention detects pipe wall vibration caused by water leakage using two sensors, and delays the output signal of the second sensor, which is attached so as to be movable in a straight line with respect to the first sensor that serves as a reference. The signal delayed by the circuit and the output signal of the first sensor used as a reference are input to a zero phase difference detection circuit that detects that the position difference is zero, and the second sensor is By moving the position of the sensor, the direction of the water leak position can be determined from the fact that the phase difference becomes zero.

(Example) Next, an example of the present invention will be described. FIG. 1 is a block diagram of a failure point direction determining device. 1 is a first sensor for detecting pipe wall vibration fixedly attached to the outside of the case 3;
The output signal 7 is applied to the first input of the zero phase difference detection circuit 5. Reference numeral 2 denotes a second sensor 1 for detecting tube wall vibration, which is mounted with a movable structure on the outside of the case 3, and its output signal 2a is input to the delay circuit 4.

Although the movable structure is not particularly illustrated, it may be any structure that can linearly and smoothly move within a predetermined range.

The output signal 6 of the delay circuit 4 is applied to the second input of the zero phase difference detection circuit 5. 8 is an output signal of the zero phase difference detection circuit 5, which can be visually recognized by inputting this output signal 8 into an analog meter or a digital meter. Although not shown in FIG. 1, an amplifier circuit is connected when the output signal levels of sensor 1 and sensor 2 are low.

Note that the sensor 2b indicated by a broken line indicates the position when the sensor 2 moves in the direction approaching the sensor 1.

The operation of the above configuration will be explained using FIGS. 2 and 3.

Figure 2 shows a case where the water leakage site is on the side of the second sensor 2 (
In the usage example shown in FIG. 4, the signal waveform is shown when there is a water leak at point A). Waveform 21 is the output signal waveform of sensor 2, waveform 22
is the waveform of the output signal 6 of the delay circuit 4, in which the output signal of the sensor 2 is delayed by a fixed delay time by the delay circuit. The waveform 23 is the waveform of the output signal 7 of the sensor 1, and the vibration propagation delay time 1. is detected later than the output signal of sensor 2. td is given by the equation 0.

t 4 = L / v ■However, L
is the distance between the centers of sensor 1 and sensor 2, and ■ is the propagation speed of vibration transmitted through the tube wall, which is a constant determined mainly by the material of the tube.

However, since the sensor 2 is a movable structure, the propagation delay time t is equal to the delay time L'L'=vτ
By moving the sensor 2 to the position (2), the phases of the output signal 6 and the output signal 7 match, and this state can be detected by the zero phase difference detection circuit 5.

Figure 3 shows a case where the water leakage site is on the side of the first sensor 1 (
In the usage example of FIG. 4, the signal waveform is shown when there is a water leak at point B). The waveform 31 is the waveform of the output signal 7 of the sensor 1, and the waveform 32 is the waveform of the output signal of the sensor 2, which are detected with a delay from the output signal of the sensor 1 by the vibration propagation delay time td. The waveform 33 is the waveform of the output signal 6 of the delay circuit 4, in which the output signal of the sensor 2 is delayed by the delay time. However,
Since τ>0, as is clear from the figure, the waveform 31 (
Since it is impossible for the output signal 7) and the waveform 33 (output signal 6) to match in phase, the zero phase difference detection circuit 5 will never output a phase matching signal.

As can be seen from the above explanation, the output signal 8 is obtained only when there is a water leakage site on the side of the second sensor 2. Therefore, as shown in FIG. By doing so, you can easily find the direction of the water leak.

FIG. 4 is a diagram showing the implementation situation at the site, in which the present device is placed on top of the excavated water pipe 10. By attaching a permanent magnet to the top of the sensor, workability in the case of steel pipes is improved. Figure 5 shows an enlarged view of the lower part.
By displaying the propagation velocity on a scale, the sensor 2 can be moved to a scale position corresponding to the pipe material. In particular, for frequently used steel pipes, asbestos pipes, PVC pipes, etc., the work efficiency can be improved by displaying the pipe type in the corresponding position. The scale display can be done by setting the delay time τ.
The distance between the sensors corresponding to the propagation velocity V depending on the pipe type is ■
It is easily obtained from Eq. Now, if we set τ = 0.2 milliseconds, we can obtain the scale shown in Table 1. In addition, in Figure 4, 4
1 is a salt pipe, 42 is a steel pipe, 43 is the direction of the water leakage point, and in FIG. 5, 51 is a water pipe.

Table 1 [Effects of the Invention] As described above, according to the present invention, by simply adjusting the position of the movable sensor according to the type of pipe, changing the direction, and placing it on the pipe wall, the direction of the underground water leakage site can be determined. Since it is easy to understand, wasteful excavation work can be avoided even if there is no skilled person.

[Brief explanation of the drawing]

``Figure 1 is a configuration diagram of a failure point direction determination device showing an embodiment of the present invention, Figures 2 and 3 are waveform explanatory diagrams of various parts showing the operation of the present invention, and Figures 4 and 5 are used. This is an explanatory diagram showing the situation 6 1...Sensor 1 2...Sensor 2 3...Case 4...Delay circuit 5...Zero phase difference detection circuit Representative Patent attorney Nori Chika Yudo Mitsumata Kobun Figure 1

Claims (1)

[Claims] a first sensor that detects vibrations of a pipe wall and converts it into an electrical signal; a second sensor that is mounted so as to be movable in a linear direction with respect to the fixed first sensor; a delay circuit that converts the output signal of the sensor into a delayed signal; and a zero phase difference detection circuit that detects that the phase difference between the output signal of the first sensor and the delayed signal is zero; Fault point direction determination device that determines direction.