JP3267430B2 - Gas leak detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas leak detecting device for detecting a gas leak in a gas pipe.

[0002]

2. Description of the Related Art Generally, a household gas meter has a function of measuring a flow rate of gas passing therethrough, and detects a gas supply pressure by a pressure switch (pressure sensor) so that the pressure is measured when the gas is not used. If a decrease is detected, or if a gas flow of a predetermined amount or more is detected using a flow meter,
When the gas flow rate is detected for a predetermined period or more, the gas shutoff valve is driven to shut off the gas flow path.
Thereby, leakage in the piping, unnatural outflow of gas, and the like are detected, accidents are prevented beforehand, and safety is assured.

FIG. 7 shows a schematic configuration of a conventional gas supply system for general households. The gas meter 1 is arranged at a position close to the house 2, and gas is supplied to a gas inlet of the gas meter 1 through a main pipe 3 buried underground and a lamp outer pipe 4. The outlet of the gas meter 1 is connected to each gas appliance inside the house 2 through the lamp inner tube 5. A gas leak alarm 6 for issuing a gas leak alarm is provided inside the house 2.

In this conventional gas supply system, gas leakage from the gas meter 1 to the gas tap 7 provided for each gas appliance in the house 2 is detected by the gas leak detection mechanism of the gas meter 1. When the gas meter 1 detects a gas leak, the gas is shut off. In addition, if there is a gas leak in the room, the gas leak alarm 6 can detect and shut off the gas or issue an alarm.

[0005]

As described above, in the conventional system, the gas leak on the downstream side of the gas meter 1 can be automatically detected by the gas meter 1, but the gas leaks to the gas meter 1 by the customer. The gas meter 1 was unable to detect gas leaks from the buried gas pipes on the premises (the inner pipes 4 outside the lamps). For this reason, gas leaks have been detected by a method such as a patrol person confirming by odor or the like at the time of regular security patrol once every three years, a meter reader being noticed by odor at the time of meter reading, and a consumer being noticed by odor.

However, since a gas leaks outside, the gas diffuses, the conventional method cannot detect a small amount of the gas leak, and it takes a long time to find the gas leak. Was. In addition, at present, periodic inspections are performed only once every three years. Therefore, there is a problem that even if there is a gas leak, it may be used for a long time without being detected and lead to an accident.

[0007] In addition, in the case of outdoor gas leakage, even if a gas leak is found due to odor, there is a problem that the location of the gas leak is often unknown.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to automatically and early detect a gas leak particularly in a gas pipe on the upstream side of a gas meter and to estimate a leak location. It is an object of the present invention to provide a gas leak detection device which can be used.

The gas leakage detecting device according to the first aspect has one end.
Is connected to cross the main pipe buried underground,
The other end is connected to the gas meter and part is buried underground.
Used for gas supply systems with installed lamp outer tubes
A than the pressure fluctuation generating means for generating a pressure fluctuation in the gas flow path of gas passes in the gas supply system, a wave due to pressure fluctuations generated by the pressure fluctuation generating means is reflected by the lamp outside the tube Pressure fluctuation detecting means for detecting pressure fluctuations caused by reflected waves generated by the pressure sensor; storage means for storing data of pressure fluctuations detected by the pressure fluctuation detecting means when the gas supply system is normal; The data of the pressure fluctuation detected by the detection means is compared with the data of the pressure fluctuation stored by the storage means to determine the gas leakage, and the gas leakage point is determined based on the temporal position of the transient pressure fluctuation. Gas leak detection means for inferring the pressure, the gas leak detection means, pressure
Of the fluctuation data, during gas leakage,
The amplitude of the transient pressure fluctuation that appears before the wave
Gas leakage based on the transient pressure change.
The location of the gas leak is estimated based on the temporal position of the motion .

In this gas leak detection device, pressure fluctuation is generated in the gas flow path by the pressure fluctuation generating means, and the pressure fluctuation due to the reflected wave generated by reflection of the wave due to the pressure fluctuation in the gas supply system is the pressure fluctuation. It is detected by the detecting means. The data of the pressure fluctuation detected by the pressure fluctuation detecting means when the gas supply system is normal is stored by the storage means. The leak detecting means compares the data of the pressure fluctuation detected by the pressure fluctuation detecting means at the time of the inspection with the data of the pressure fluctuation stored by the storage means. The location is guessed.

[0011]

[0012] Claim 2 gas leak detection system according, in gas meter and pressure fluctuation generating means and the pressure fluctuation detecting means in the gas leak detection device according to claim 1 is to measure the flow rate of gas through the gas channel It is provided in.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing a gas supply system including a gas leak detection device according to one embodiment of the present invention. This gas supply system supplies gas a through a main pipe or branch pipe (hereinafter referred to as main pipe) 10 buried underground.
Is sent to a gas meter 20 through a lamp outer tube 11 which is also partially buried in the ground, and the gas meter 20 measures the flow rate. Zu).

The gas meter 20 is provided with a safety function using a microcomputer. Inside the gas meter 20, a gas inlet 21 and a gas outlet 2 are provided.
2 and a gas pipe 23 constituting a part of a gas flow path in the gas supply system is provided. The gas pipe 23 is provided with a speaker 24 as a pressure fluctuation generating means for generating pressure fluctuation in the gas flow path in order from the gas inlet 21 side.
And a microphone 25 as pressure fluctuation detecting means for detecting a pressure fluctuation caused by a pressure fluctuation wave generated by the speaker 24, that is, a reflected wave generated by reflection of a sound wave in the gas supply system, and a gas pipe 23 to be shut off. And a gas flow meter 27 for measuring the flow rate of the gas passing through the gas pipe 23.

The gas meter 20 is provided with a control unit 30 for inputting output signals of the microphone 25 and the gas flow meter 27 and for controlling the speaker 24 and the gas cutoff valve 26.

FIG. 2 shows a control unit 30 in the gas meter 20.
FIG. 2 is a block diagram showing a configuration of a peripheral device. The control unit 30 includes a CPU (central processing unit) 31, a ROM (read only memory) 32, a RAM (random access memory) 33, a clock 34 for time measurement, and an input / output port 35. Are connected to each other by a bus 36. The input / output port 35 has a speaker 2 in addition to the gas flow meter 27 and the microphone 25 described above.
4, a drive circuit 38 for driving the gas cutoff valve 26, and a drive circuit 40 for driving an alarm lamp 39 provided in the gas meter 20 are connected. In the control unit 30, the CPU 31
By executing the program stored in the ROM 32 using the M33 as a working area, the gas meter 2
A function as a gas leakage detection device for detecting gas leakage in the lamp outer tube 11 on the upstream side of 0 is realized.

FIG. 3 is a functional block diagram showing functions of the gas leakage detection device of the present embodiment. As shown in this figure, the gas leak detection device has a pressure fluctuation generating means 41 for generating a pressure fluctuation in a gas flow path, and a wave caused by the pressure fluctuation generated by the pressure fluctuation generating means 41 in a gas supply system. Pressure fluctuation detecting means 42 for detecting pressure fluctuation due to reflected waves generated by reflection, and first storage means 43 for storing data of pressure fluctuation detected by pressure fluctuation detecting means 42 when the gas supply system is normal. And a second storage means 44 for storing data of the pressure fluctuation detected by the pressure fluctuation detecting means 42 during the inspection.

The gas leakage detecting device further calculates a change amount of the pressure fluctuation data stored in the first storage means 43 with respect to the pressure fluctuation data stored in the second storage means 44. Means 45, a leak discriminating means 46 for discriminating a gas leak based on the change amount obtained by the change amount calculating means 45, and a first storage means when the gas discriminating means 46 determines that the gas is leaking. 43 and the pressure fluctuation data stored by
Leak estimating means 4 for estimating a gas leaking part by comparing with pressure fluctuation data stored by the storing means 44 of FIG.
7 and alarm means 48 for notifying an alarm when gas leakage is determined by the leak determination means 46. The change amount calculating means 45, the leak determining means 46, and the leak location estimating means 47 constitute a leak detecting means.

The change amount calculating means 45 changes the amplitude of the transient pressure fluctuation (hereinafter referred to as an initial transient phenomenon) which appears in the data of the pressure fluctuation at a time before the reflected wave in the normal state at the time of gas leakage. The amount (the amount of change with respect to the amplitude in the normal state) is calculated. When the amount of change in the amplitude exceeds a predetermined value, the leak determination means 46 determines that gas leakage due to corrosion or the like has occurred in the inner tube 11 outside the lamp. The leak location estimating means 47 estimates a gas leak location based on the temporal position (time) of the initial transient phenomenon.

The pressure fluctuation generating means 41 is connected to the speaker 2
4, and the pressure fluctuation detecting means 42 is realized by the microphone 25. The first storage unit 43 and the second storage unit 44 are realized by the RAM 33, and the change amount calculation unit 45, the leak determination unit 46, and the leak location estimation unit 47 are realized by the control unit 30,
The warning means 46 is realized by a warning lamp 39.

Next, the operation of the gas leakage detection device according to the present embodiment will be described with reference to the flowchart shown in FIG.

In this gas leak detecting device, first, when the gas supply system is normal, such as when the gas meter 20 or a new pipe is installed, the pressure fluctuation generating means 41 generates a pulse-like pressure fluctuation (pulse sound). A sound wave due to the pressure fluctuation is emitted toward the lamp outer tube 11 (step S101). This sound wave is reflected at the connection between the lamp outer tube 11 and the main tube 10, and returns to the gas meter 20 side. The pressure fluctuation due to the reflected wave is detected by the pressure fluctuation detecting means 42 (Step S102). Then, the pressure fluctuation detecting means 42
The data of the pressure fluctuation in the normal state detected by the first storage means 43 is stored in the first storage means 43, and the amplitude of the portion corresponding to the initial transient phenomenon is detected from the data to obtain the first data.
(Step S10)
3). FIG. 5 shows an example of a pressure fluctuation pattern in the normal state.

Next, at the time of inspection performed at a predetermined cycle, a pulse-like pressure fluctuation (pulse sound) is generated by the pressure fluctuation generating means 41, and a sound wave due to the pressure fluctuation is generated by the lamp inner tube 1.
1 (step S104), and a pressure fluctuation caused by a reflected wave generated by reflection of the sound wave in the gas supply system is detected by the pressure fluctuation detecting means 42 (step S104).
105). Then, the data of the pressure fluctuation detected by the pressure fluctuation detecting means 42 is stored in the second storage means 44, and the position and amplitude of the initial transient phenomenon are detected from the data and stored in the second storage means 44. (Step S106).

FIG. 6 shows an example of a pressure fluctuation due to a reflected wave when a gas leak of 620 liter / hour occurs in the outer tube 11 of the lamp. In this figure, the reference numeral 51 indicates that the leakage point is from the gas meter 20 to 3.
Pressure fluctuation at 5 m, 52 indicates gas meter 2
The pressure fluctuation when the leakage point is 0 to 2.5 m, the pressure fluctuation 53 when the leakage point is 1.5 m from the gas meter 20, and the pressure fluctuation 54 when the leakage point is 0.5 m from the gas meter 20. As shown in this figure, when gas leakage has occurred, an initial transient phenomenon 55 appears before a reflected wave reflected at a connection portion between the outer lamp inner tube 11 and the main tube 10. The amplitude of the initial transient 55 is related to the gas leakage amount, and the temporal position of the initial transient 55 is related to the gas leak location. Therefore, gas leakage can be determined from the amplitude of the initial transient 55, and a gas leak location can be estimated from the temporal position of the initial transient 55.

In this embodiment, the change amount calculation means 45 uses the amplitude data stored in the first storage means 43 and the amplitude data stored in the second storage means 44 to perform an initial transient phenomenon. Is calculated (step S107). The leak determination means 46 determines whether or not the amount of change in the amplitude exceeds a predetermined value (step S108). If the amount of change does not exceed the predetermined value (N), the process returns to step S104. If the variation exceeds a predetermined value (Y), it is determined that gas leakage due to corrosion or the like has occurred in the lamp outer tube 11.

When it is determined that a gas leak has occurred, the leak location estimating means 47 stores the pressure fluctuation data stored in the first storage means 43 and the second storage means 4.
Then, the leak location is estimated based on the temporal position of the initial transient phenomenon by comparing the data with the pressure fluctuation data stored in step 4 (step S109). For estimating the leak location, for example, a table indicating the relationship between the temporal position of the initial transient phenomenon and the distance from the gas meter 20 at the leak location, which is obtained in advance by an experiment, is used. The leak location may be represented by a distance from the gas meter 20 or may be represented by a distance from a connection portion between the lamp outer tube 11 and the main tube 10.

When it is determined that a gas leak has occurred, the gas leak detecting device issues a warning by the warning means 48 (step S110), and the gas shutoff valve 26
To shut off the gas flow path and end the operation. The alarm method is not limited to the alarm lamp 39, but may be a buzzer. By shutting off the gas flow path by the gas shut-off valve 26, the gas user is forcibly notified of an abnormality. It may be one that prompts a report.

The gas meter 20 detects the pressure fluctuation data in the normal state (step S1 in FIG. 4).
By providing a reset switch for starting 01 to S103), when the gas supply system is changed due to remodeling or the like, it is possible to reset the data of the normal pressure fluctuation.

As described above, according to the gas leak detection device of the present embodiment, a sound wave is periodically emitted toward the upstream side of the gas meter 20 in the gas flow path and reflected in the gas supply system. The gas leakage in the lamp outer tube 11 on the upstream side of the gas meter 20 is detected based on the secular variation of the amplitude of the initial transient phenomenon in the pressure fluctuation caused by the reflected wave generated at the same time. Since the location of the gas leak is estimated based on the position, the gas meter 20
A gas leak in the lamp outer tube 11 on the upstream side can be automatically and early detected, and a gas leak location can be known.

Further, in the gas leak detection device of the present embodiment,
Since the gas leak is detected without shutting off the gas, the gas leak can be detected without stopping the gas supply to the customer.

Further, in the gas leak detecting device of the present embodiment,
Since the location of the gas leak can be estimated, it is possible to improve the time efficiency of the pipe replacement work and reduce the cost.

The present invention is not limited to the above embodiment,
For example, in the embodiment, all of the components of the gas leak detection device are provided in the gas meter 20, but all or a part of these components may be provided separately from the gas meter 20 in the vicinity of the gas meter 20. good. For example, speaker 2
4 and the microphone 25 are disposed in the lamp outer tube 11 near the gas meter 20, and the control unit 3 of the gas meter 20 is provided.
It may be connected to 0.

The wave due to the pressure fluctuation is not limited to the audible sound, but may be a compression wave having a lower or higher frequency than the audible sound. Further, the pressure fluctuation generating means is not limited to the speaker 24, and may be a proportional valve or an on-off valve which generates a compression wave by opening and closing the gas flow path in a short time.

In the embodiment, a sound wave is emitted toward the upstream side of the gas meter 20 to detect a gas leak in the lamp outer tube 11 on the upstream side of the gas meter 20. , And it is also possible to detect gas leakage in the piping downstream of the gas meter 20. Therefore, according to the present invention, it is possible to detect gas leakage in the pipe from the main pipe to the gas tap in the house.

[0036]

As described above, according to the gas leakage detecting device of the present invention, the pressure fluctuation generating means for generating the pressure fluctuation in the gas passage, and the wave caused by the pressure fluctuation generated by the pressure fluctuation generating means. And pressure fluctuation detecting means for detecting pressure fluctuation due to reflected waves generated by reflection in the gas supply system, and storing data of the pressure fluctuation detected by the pressure fluctuation detecting means when the gas supply system is normal. By comparing the data of the pressure fluctuation detected by the pressure fluctuation detecting means at the time of the inspection with the data of the pressure fluctuation stored by the storage means,
Since the gas leak is determined and the gas leak location is estimated based on the comparison result, the gas leak in the gas pipe on the upstream side of the gas meter can be automatically and early detected, and the leak location can be estimated. It has the effect that it can be done.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a gas supply system including a gas leak detection device according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control unit of the gas meter in FIG. 1 and its surroundings.

FIG. 3 is a block diagram for explaining a function of the gas leakage detection device of FIG. 1;

FIG. 4 is a flowchart for explaining the operation of the gas leak detection device of FIG. 1;

5 is a characteristic diagram showing an example of a pattern of pressure fluctuation in a normal state detected by the gas leakage detection device of FIG.

6 is a characteristic diagram showing an example of a pattern of pressure fluctuation at the time of occurrence of gas leakage detected by the gas leakage detection device of FIG.

FIG. 7 is an explanatory diagram for explaining a conventional gas supply system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Main pipe 11 Lamp outer tube 20 Gas meter 24 Speaker 25 Microphone 26 Gas shutoff valve 30 Control part

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G01M 3/24 G01F 1/00 G01F 15/06 G01M 3/00

Claims (2)

(57) [Claims] 1. One end intersects with a main pipe buried underground.
And the other end is connected to the gas meter.
Gas supply with a lamp outer tube partially buried underground
A gas leak detection device used in a system, comprising: a pressure fluctuation generating means for generating a pressure fluctuation in a gas flow path through which gas passes in the gas supply system; and a wave generated by the pressure fluctuation generated by the pressure fluctuation generating means. storage There the pressure fluctuation detecting means for detecting a pressure variation due to the reflected wave generated by reflection in the lamp outer inner pipe, the data of the detected pressure fluctuations by the pressure fluctuation detecting means when the gas supply system is normal Storage means for comparing the data of the pressure fluctuation detected by the pressure fluctuation detection means at the time of inspection with the data of the pressure fluctuation stored by the storage means to determine gas leakage, and to determine the transient pressure fluctuation. Gas leak detecting means for estimating a gas leak location based on a temporal position , wherein the gas leak detecting means includes
At the time of leakage
Discriminates gas leaks based on the amplitude of emerging transient pressure fluctuations
And based on the temporal position of the transient pressure fluctuation.
And a gas leak detecting device for estimating a gas leak location . 2. A gas leak according to claim 1, wherein said pressure fluctuation generating means and said pressure fluctuation detecting means are provided in a gas meter for measuring a flow rate of a gas passing through said gas flow path. Detection device.