JP3023199B2 - Acoustic pipe length measuring instrument - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic pipe length measuring instrument for measuring the length of a pipe using sound waves.

[0002]

2. Description of the Related Art Gas pipes and pipes for signal cables have been used for a long time while being buried underground.

[0003] Taking a gas pipe as an example, a gas pipe buried underground is composed of a main pipe and a service pipe branched from the main pipe to each home or each business. A gas meter is connected to the section and is provided so as to be exposed on the ground.

FIG. 4 is a diagram showing a positional relationship among the main pipe, the service pipe, and the gas meter.

In a portion A where the gas pipe is buried underground (for example, under a road), a service pipe 2a branches off from the main pipe 1, and the service pipe 2a is bent at several places by an elbow 3 or the like. . The elbow is a joint pipe for joining the service pipes at an angle, and has a small radius of curvature. A gas meter 4 is connected to the service pipes 2b and 2c at a portion B where the gas pipe is exposed to the ground. For example, the gas meter 4 is fixed to the outer wall of a building (not shown), and the service pipe 2d is connected to the building. Piped inside.

When a gas pipe buried underground is corroded or damaged, it is necessary to repair or replace the gas pipe. In that case, the ground is dug to expose the service pipe. There is a method of repairing by letting it go, and a non-digging inner surface repair method of repairing a service pipe without digging the ground. The non-excavation inner surface repair method is a method in which a resin in a flowing state is poured into a service pipe requiring repair from the outside, and then evacuated and cured to coat the resin on the inner surface of the service pipe. Its development is urgent because it is advantageous in terms of cost and security. However, in this method, if a large amount of resin is poured from the outside, the internal pipe is clogged with the resin.
Is not enough. Therefore, in this non-drilling inner surface repair method, it is necessary to calculate the volume in the pipe in advance to measure the amount of resin poured into the pipe, and since the internal diameter of the serving pipe is known, measure the entire length of the serving pipe. It is necessary to do.

Conventionally, as a technique for measuring the length of a service pipe, a method using a sound wave as shown below has been known (Papers of the Acoustical Society of Japan, March 1990).

(1) Long tube measuring system As shown in FIG. 5, one speaker 6 and two microphones 7 and 8 are attached to one end of the long tube 5, and
An oscillator 9 is connected to the microphone 6, and an oscilloscope 10 is connected to the microphones 7 and 8. In this system, a pulsed sound wave emitted from a speaker 6 is received by two microphones 7 and 8, and the waveform of the sound wave is converted to an oscilloscope 1.
Observe at 0 and calculate the speed of sound, and the sound wave is
The length of the long tube 5 is measured by calculating the time of propagation from the end to the end 5b.

(2) P.I. E. FIG. Tube measuring system As shown in FIG. E. FIG. A speaker 12 is attached to one end of a (polyethylene) tube 11, and a microphone 13 is attached to the other end.
The speaker 12 and the microphone 13 are connected to a measuring device 14. This system measures the length of the tube 11 from the time from when a pulse-like sound wave of several KHz is emitted from the speaker 12 until it is received by the microphone 13 and the speed of sound. In the drawing, both the speaker 12 and the microphone 13 are separated from the tube 11, but are actually in close contact with each other.

[0010]

Generally, when measuring the length of a sealed tube using sound waves, the sound speed of the sound waves transmitted through the tubes varies depending on the type, composition and temperature of the gas in the tubes. In a measuring instrument that measures the length of a pipe based on the time from the transmission of a sound wave into the pipe to the return as in systems (1) and (2), the propagation time of the sound wave changes, The measured value of the path length varies depending on the conditions.

The present invention has been made in view of the above points, and has as its object to accurately measure the length of a pipe without being affected by the type and temperature of gas in the pipe.

[0012]

According to the present invention, there is provided a sound generating means for transmitting a pulsed sound wave from one end of a tubular member into an internal space formed in the tubular member. Sound collecting means for collecting pulsed sound waves reflected at the other end of the tubular member, temperature detecting means for detecting the temperature of gas in the internal space, and determining the type of gas present in the internal space Gas determination means, storage means for storing a reference sound velocity value at a reference temperature for each of a plurality of gas types, and the reference sound velocity value of the gas in the internal space determined by the gas determination means is obtained from the storage means. Calculating a sound velocity value at the detected temperature of the gas from the reference sound velocity value based on the temperature of the gas in the internal space detected by the temperature detection means, and the sound velocity value and a pulsed sound wave from the sound generation means Issued accomplished by acoustic pipe length measuring apparatus comprising a calculating means for calculating a conduit length of the tubular member time, from to be collected by the sound collecting means from.

[0013]

According to the acoustic pipe length measuring device of the present invention, the pulsed sound wave transmitted from one end of the tubular member by the sound generating means is reflected at the other end of the tubular member, and the sound is collected by the sound collecting means at one end of the tubular member. While measuring the time until the temperature is measured, the temperature in the tubular member is detected by the temperature detecting means, the sound speed of the gas in the tube is calculated from the detected temperature, and the time and sound speed obtained by the time measurement are calculated. Is configured to measure the length of the tube from.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of an embodiment of a pipe length measuring instrument according to the present invention.

As shown in FIG. 1, the pipe length measuring device includes a coupling member 16, amplifiers 17 and 18, a D / A converter 19, and an A / A converter.
D converter 20, temperature sensor drive circuit 21, CPU 22,
It comprises a display 23, a switch S and a memory 24. The coupling member 16 is formed of, for example, a metal tubular member, and can be detachably attached to the service pipe 28 by a screw groove 16a formed inside one end thereof. The other end of the coupling member 16 has a speaker 25 and a microphone 26
Is fixed near the other end, and a temperature sensor 27 for measuring the temperature inside the pipe is fixed through the pipe wall, and the tip is exposed inside the pipe. The coupling member 16 is formed such that one end of the service pipe 28 is in a closed state when attached to the service pipe 28. Note that the temperature sensor 27 and the temperature sensor drive circuit 21 constitute a temperature detecting unit.

The speaker 25 sends a pulsed sound wave into the service pipe 28 based on a command from the CPU 22, and the microphone 26 collects the reflected sound from the service pipe 28,
The output signal is amplified by the amplifier 18.

The A / D converter 20 converts an analog signal from the amplifier 18 into a digital signal.

The temperature sensor 27 is constituted by, for example, a thermistor, and converts the temperature in the service pipe 28 into a resistance value and detects the resistance value. However, the present invention is not limited to this, and a thermocouple may be used.

The temperature sensor drive circuit 21 includes a temperature sensor 27
Is converted into a voltage change.

The memory 24 stores data on the relationship between the type of gas (for example, natural gas and propane gas) in the service pipe 28 and the sound velocity value at a reference temperature (for example, 0 ° C.). The selection of the sound velocity data corresponding to the type is performed by switching the switch S by the operator, so that the pipe length can be measured for different gases. In addition, the internal pipe 28 using a gas sensor (not shown).
It is also possible to determine the type of gas in the inside and read out the sound velocity data corresponding to the type of gas.

The display 23 displays the value of the length of the service pipe 28 measured by this measuring instrument, and may use a liquid crystal display device or an LED (light emitting diode).

The CPU 22 is composed of, for example, a microprocessor, and is connected to the D / A converter 19, the A / D converter 20, the display 23, and the switch S.
The CPU 22 instructs the D / A converter 19 to generate a signal for generating a pulsed sound wave, receives the reflected wave of the pulsed sound wave collected by the microphone 26 from the A / D converter 20, transmits the sound wave, and collects the sound wave. The sound speed value at the reference temperature read out from the memory 24 for the type of gas in the service pipe 28 while receiving the signal of the temperature in the service pipe 28 from the temperature sensor drive circuit 21 while measuring the time until sounding. The sound velocity is calculated based on the above data. The CPU 22 calculates the length of the service pipe 28 from the calculated sound speed and the above-described time, and displays the calculated value on the display 23.

Next, the operation of the pipeline length measuring device will be described with reference to FIGS.

FIGS. 2 and 3 are flowcharts for explaining the operation of the acoustic pipe length measuring instrument.

In FIG. 2, when the measurement of the length of the service pipe 28 is started, the CPU 22 initializes the parameters and declares the array "DATA (4000)".
“DATA (4000)” is an array having a number of 4000, in which values obtained by sampling sound signals collected and output by the microphone 26 at time intervals of Δt (s) are arranged in the order of time. (S-
1).

0 is substituted for a variable N representing the number of repetitions of the operation (S-2), and 0 is substituted for DATA (*). This means that all elements of the array DATA (4000) are set to 0 (S-3).

An analog signal for generating a pulsed sound wave is output from the D / A converter 19 to the amplifier 17 (S
-4). As a result, a pulsed sound wave is generated from the speaker 25 in the internal pipe 28 for one cycle.

0 is substituted for a variable t representing the number of arrays (S-5), and the output “d” of the amplifier 18 is supplied to the A / D converter 20.
“ata” ”(S-6). This is a signal of the reflected wave of the pulsed sound wave received by the microphone 26 (output “da
ta ”) is taken in every sampling time Δt. The value of DATA (t) + data is substituted for each element DATA (t) of the array "DATA (4000)" (S-6). The value of data is the output value of the amplifier 18 at the variable t, and the element DATA of each array
(T). The variable t + 1 is substituted for the variable t (S-8), and it is determined whether or not the value of the variable t is less than 4000. If the value is less than 4000, the process returns to step (S-6) (S-9). As a result, data for one cycle of the pulsed sound wave is sampled. The value of N + 1 is substituted for the variable N (S-10), and the process proceeds to the next step (S-11).

In FIG. 3, it is determined whether or not the value of the variable N is less than 100. If the value of the variable N is less than 100, the operations from step (S-4) to step (S-10) are repeated ( S-11). This is to remove noise by averaging 100 times of data.
N represents the number of additions. By the way, if the averaging is performed 100 times, the noise intensity is reduced to 1/100 square root, that is, 1/10 intensity. Note that the value of the number N is not limited to 100.

If the variable N is 100 or more in step (S-11), the A / D converter 20 reads the output voltage of the temperature sensor 27 (S-12).

The CPU 22 has 4000 array elements DAT.
The value of t that maximizes the absolute value is selected from A (t) (S-13). In this case, the amplitude of the reflected wave at the open end of the service pipe 28 is maximized, and the maximum value is used. Here, the maximum value is obtained because there are two maximum values because the waveform of the reflected wave is theoretically symmetrical with the positive component and the negative component. When a sound wave is output from the speaker 25, the vibration of the vibration surface of the speaker 25 vibrates weakly on one surface, for example, the surface corresponding to the positive component, and the surface corresponding to the negative component vibrates strongly due to inertia. It becomes asymmetric. As a result, the peak value of the amplitude of the negative component (second) is selected.

The sound velocity value vo (m / s) at 0 ° C. of the gas inside the service pipe 28 is read from the memory 22 (S−
14). As described above, the measurer switches the switch S to change the switch S to a value corresponding to the type of gas in the service pipe 28.
The sound velocity value at ° C is obtained.

Using the temperature T (° C.) in the service pipe 28 obtained by the temperature sensor 27 and the temperature sensor drive circuit 21, the sound velocity v (m / m /
s) (S-15),

[0035]

V = vo {1 + T / 273} ^1/2 Next, the pipe length L (m) of the service pipe 28 is calculated by the following equation 2 (S-16).

[0036]

L = v · t · Δt / 2 The value of the pipe length L of the service pipe 28 calculated in this way is indicated on the display 2
3 is displayed (S-17).

As described above in detail, according to the present embodiment, the temperature of the gas in the service pipe 28 is detected, and the sound velocity value at that temperature is calculated using the detected temperature. Since the length of the pipe of the service pipe 28 is calculated using the sound velocity value, the length of the service pipe 28 can be accurately measured irrespective of the temperature and type of the gas in the service pipe 28.

[0038]

As described above, in the present invention, the sound velocity at the reference temperature of the gas existing in the tubular member is stored, and the temperature in the tubular member is detected by the pipe length measuring device. Since the time and temperature from when the pulsed sound wave was sent to when the sound was collected and the sound velocity value at this measured temperature were calculated, and the sound velocity value was used, the pipe length of the tubular member was measured. The length of the tubular member can be accurately measured regardless of the type of gas in the tubular member or the environmental temperature.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of an acoustic pipe length measuring device according to the present invention.

FIG. 2 is a flowchart for explaining the operation of the pipeline length measuring device shown in FIG.

FIG. 3 is a flowchart continuing from the flowchart shown in FIG. 2;
It is a chart.

FIG. 4 is a diagram showing a positional relationship between a gas pipe and a gas meter.

FIG. 5 is a diagram showing an example of a conventional pipeline length measuring system.

FIG. 6 is a diagram showing another example of a conventional pipeline length measuring system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 16 Coupling member 17, 18 Amplifier 19 D / A converter 20 A / D converter 21 Temperature sensor drive circuit 22 CPU 23 Display 24 Memory 25 Speaker 26 Microphone 27 Temperature sensor

Continuation of the front page (56) References JP-A-64-78184 (JP, A) JP-A-1-237484 (JP, A) JP-A-1-96507 (JP, A) JP-A-58-193409 (JP) , A) JP-A-4-190106 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01B 17/00-17/04 G01S 15/88

Claims (1)

(57) [Claims] 1. A tubular member formed from one end of the tubular member.
Sounding means for sending pulsed sound waves into the enclosed internal space
And reflection at one end of the tubular member at the other end of the tubular member
Sound collecting means for collecting a pulsed sound wave, and a temperature detecting means for detecting a temperature of a gas in the internal space.
When,A gas detector for determining the type of gas present in the internal space
Cutting means, The reference sound velocity value at the reference temperature for each type of gas Record
Memory means to remember,Before the gas in the internal space determined by the gas determination means
The reference sound velocity value is obtained from the storage means, and the temperature detection value is obtained.
Based on the temperature of the gas in the interior space detected by the stage
The sound velocity at the detected temperature of the gas from the reference sound velocity value
The sound speed value and the sounding means. Pulsed sound
After the waves were sentBy the sound collecting meansUntil the sound is collected
And the pipe length of the tubular member fromCalculation to calculatehand
An acoustic pipe length measuring instrument comprising: a step;