JP3445686B2 - 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 leak detection device for detecting the presence or absence of gas leakage in a supply pipe buried underground between a main pipe and a customer.

[0002]

2. Description of the Related Art Generally, a gas meter has a function of measuring the amount of gas used and a safety function of detecting the presence or absence of gas leakage and immediately issuing an alarm when a gas leakage occurs. However, the safety function of this gas meter can detect only gas leaks on the downstream side of the gas meter, that is, between the gas meter and the gas appliance, and on the upstream side of the gas meter, that is, between the road and the home boundary and the gas meter. It was not possible to automatically detect the presence or absence of gas leakage in the supply pipe buried in the ground (between the branch pipe and the gas meter). Therefore, it is obligatory to regularly check for leakage between the main branch pipe and the gas meter by using a special sensor (combustion substance detection sensor).

[0003]

However, according to this conventional method, it takes a lot of labor to detect the gas leak, and in addition, it is possible to inspect only once every three years.
It is desired to develop a method that can detect gas leakage more easily without requiring manpower.

The present invention has been made in view of the above problems, and an object thereof is to be able to automatically detect the presence or absence of leakage in a supply pipe buried in the ground, and to eliminate the need for manpower for detection. It is an object of the present invention to provide a leak detection device that is capable of achieving the above and improved safety.

[0005]

The invention according to claim 1 is
A leak detection device for detecting the presence or absence of leakage of a fluid flowing through a supply pipe installed between a main branch pipe and a customer, which has a predetermined flow path diameter, in the middle of the supply pipe, The first flow rate measuring means for measuring the flow rate of the fluid flowing through the pipe, the blocking means for blocking the fluid flowing through the supply pipe, and the flow passage having a smaller flow passage diameter than the supply pipe, and the two inlets and outlets are provided for the supply. A backflow detecting channel provided at a position corresponding to each of the front and rear of the blocking means of the pipe, a second flow rate measuring means for measuring a flow rate of a fluid flowing through the backflow detecting channel, and the first flow rate measuring means. The detection result of the flow rate detecting means is monitored, and when the flow rate of the fluid flowing through the supply pipe is in a minute flow rate mode less than a predetermined flow rate, the shutoff means is driven to shut off the flow path, and then the second flow rate is set. The measurement result of the flow rate detection means When the backflow is detected by the backflow detection means for detecting the occurrence of the backflow of the fluid in the backflow detection flow path, the backflow is equal to or more than a predetermined flow rate, and the number of times of detection is a predetermined value. When it reaches, it is provided with a leak detecting means for outputting an alarm signal because a leak has occurred in the supply pipe, and an alarm notifying means for receiving an alarm signal from the leak detecting means and notifying that there is a leak. .

In this leak detection device, when the flow rate of the fluid flowing through the supply pipe is in the minute flow mode in which the flow rate is less than a predetermined flow rate,
The blocking means is driven to block the flow path. As a result, the flow of fluid such as gas is switched to the reverse flow detection flow path side. And
In this state, when fluid is leaking from the supply pipe, a backflow is generated in the backflow detection channel and the supply pipe, and the backflow is detected by the backflow detection means. When the backflow detected by the backflow detection means is equal to or higher than a predetermined flow rate and the number of times of detection reaches a predetermined value, an alarm signal is output as a leak has occurred in the supply pipe, and the alarm notification means notifies the alarm. Is done.

According to a second aspect of the present invention, in the leak detecting device according to the first aspect, the backflow detecting means detects a pressure drop state of the fluid at a position downstream of the backflow detecting flow path of the supply pipe. And a pressure drop detecting means for detecting a backflow occurs when the pressure drop detecting means does not detect a steep pressure drop and when the flow rate is detected by the second flow rate detecting means. It is configured in.

According to a third aspect of the present invention, in the leak detection device according to the second aspect, when the backflow detection and the leak detection means output an alarm signal, the pressure drop detection means causes a steep pressure drop. When it is detected, or when the backflow detection means does not detect a backflow of a predetermined amount or more, the shutoff means is restored and the flow path is opened.

According to a fourth aspect of the present invention, in the leakage detection device according to the third aspect, the leakage detection means detects a pressure fluctuation of the fluid at a position upstream of the reverse flow detection flow path of the supply pipe. Includes a pressure fluctuation detecting means for detecting the presence or absence, and after the backflow detecting means detects a backflow state, if no pressure fluctuation is detected by the pressure fluctuation detecting means, it is considered that there is a possibility of leakage and a predetermined amount or more. It is configured to determine whether or not there was a backflow of.

The invention as defined in claim 5 is defined by claim 1 through claim 4.
In the leak detecting device according to any one of 1 to 3, a pressure fluctuation suppressing means for suppressing an influence due to a pressure fluctuation on the main branch side at the time of leak detection is included in a position near the main branch in the supply pipe. As a result, the influence of the pressure fluctuation on the main branch side can be suppressed, and the leak can be detected more accurately. That is, in particular, when the pressure on the main branch side decreases, a backflow occurs in the supply pipe due to this, so that this is not erroneously recognized as a backflow due to leakage.

According to a sixth aspect of the present invention, in the leakage detection device according to the fourth aspect, any one of a supply system in which the supply pipe is branched into a plurality of systems, and a plurality of gas meters are connected to these systems, respectively. When the pressure fluctuation is detected by the pressure fluctuation detecting means, which is installed at the inlet of one of the systems, the leak detecting means determines that gas is being used in another system and there is a possibility of leakage in the supply pipe. It is configured to determine that there is no.

According to a seventh aspect of the present invention, there is provided a leakage detection device according to the fourth aspect, wherein the supply pipe is branched into a plurality of systems, and a plurality of gas meters are connected to these systems, respectively. When the pressure fluctuation is detected by the pressure fluctuation detecting means, which are respectively installed at the inlet portions of the above systems, the leak detecting means respectively,
It is configured to judge that there is no possibility of leakage in the supply pipe because gas is being used in another system.

The invention as defined in claim 8 is defined by claim 1 through claim 7.
The leak detection apparatus according to any one of 1 to 3, further comprising a communication unit, the communication unit being connected to a meter-reading center through a telephone line so as to notify the meter-reading center of the occurrence of the leak.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows the configuration of a leak detection device according to an embodiment of the present invention. The leak detection device of the present embodiment is a supply pipe 12 for a fluid (a gas in this embodiment) flowing through a supply pipe 12 buried in the ground between the main branch pipe 11 and a customer.
It is for detecting the presence or absence of leakage in the middle of the process. Here, the supply pipes 12 are two supply pipes 12A, 12A corresponding to a plurality of (two in this embodiment) systems A and B of the consumer group.
It branches to 12B. A plurality (here, four) of gas meters A ₁ , A ₂ , A ₃ , and A ₄ are connected to the supply pipe 12A, and a plurality (four here) of gas meters B ₁ , B ₂ , B ₃ and B ₄ are connected to each other.

The pipe diameter is, for example, the main branch pipe 11
Is 100 to 200 mm, and the supply pipe 12 is 80 to 100 m
m, and the supply pipes 12A and 12B are 40 to 80 mm, respectively.

The leakage detection device of this embodiment is composed of a device body 10
0 and a check valve 200 as a pressure fluctuation suppressing means. The apparatus main body 100 is installed, for example, at the entrance of the ground portion of the supply pipe 12A in the system A.

FIG. 2 shows a concrete structure of the apparatus main body 100. The apparatus main body 100 includes a backflow detection flow passage 13 having a smaller flow passage diameter (for example, 5 to 20 mm) than the supply pipe 12A. This reverse flow detection channel 1
3, one of the entrances and exits 13a is in the middle of the supply pipe 12 (hereinafter,
This position is connected to a first point), and the other inlet / outlet 13b is connected to a point downstream of the first point of the supply pipe 12A (hereinafter, referred to as a second point). At, it becomes a passage for backflow gas. A flow rate sensor (F ₂ ) 103 as a second flow rate measuring means is installed in the backflow detection flow path 13.
The flow rate sensor 103 is composed of a sensor capable of measuring a flow rate in the range of 0 to 500 liters / hour, for example, a flow sensor.

On the other hand, on the side of the supply pipe 12A, a shutoff valve 101 is installed as a shutoff means between the first point and the second point. The shutoff valve 101 is configured by a bidirectional valve that can be electrically shut off and restored, and is in an open state (return state) in a normal state and a closed state (shutoff state) when a leak is detected. Each is set. A flow rate sensor (F ₁ ) 102 as a first flow rate measuring means for detecting the flow rate of the gas flowing through the supply pipe 12A is installed near the shutoff valve 101. The flow rate sensor 102 is composed of a sensor capable of measuring a flow rate in the range of 0 to several m ³ / h.

A pressure sensor (P ₁ ) 104 as a pressure drop detecting means for detecting a drop in gas pressure is arranged downstream of the second point of the supply pipe 12A.
When the pressure sensor 104 detects a steep pressure drop, it is determined that a gas appliance is being used by a customer on the downstream side of the apparatus main body 100, and a gas leak has not occurred in the supply pipe 12. It On the other hand, when the pressure sensor 104 does not detect a sharp pressure drop, it is determined that gas leakage may occur.

A pressure sensor (P ₂ ) 105 as a pressure fluctuation detecting means for detecting fluctuations in gas pressure is arranged upstream of the first point of the supply pipe 12A.
When the pressure sensor 105 detects a pressure fluctuation of a predetermined amount or more, it is determined that a gas appliance is used in another system B, and when the pressure fluctuation is not detected, the supply pipe 12 is used. It is judged that there may have been a gas leak in.

The shutoff valve 101 and the flow rate sensors 102, 1
03 and the pressure sensors 104 and 105 are connected to a microcomputer 106 as a control means. The microcomputer 106 includes the flow rate sensor 102.
When the flow rate detected by means of the micro flow rate mode is less than a predetermined flow rate (for example, 300 liters / hour), the shutoff valve 101 is switched from the open state to the closed state, and then the pressure sensor 104 and the flow rate sensor 103 detect the flow rate. Based on the result, the backflow state of gas is detected to determine the presence or absence of leakage, and if it is determined that there is leakage, an alarm signal is output. That is, as shown in FIG.
When a hole 12a is opened in the hole and a gas leak occurs through the hole 12a, the gas flows backward through the supply pipe 12 from the reverse flow detection flow path 13. When the flow rate of the reverse flow is detected by the flow rate sensor 103, the flow rate is equal to or higher than a predetermined flow rate, and the number of times of detection (backflow detection number value) reaches a predetermined value, a gas leak occurs in the supply pipe 12. To judge. That is, the microcomputer 106 has a function as a backflow detecting means and a function as a leak detecting means together with the pressure sensors 104, 105 and the flow rate sensor 103.

The microcomputer 106 also includes
An alarm informing unit 107 is connected as an alarm informing unit for informing an abnormal state. The alarm notification unit 107 is composed of, for example, a lamp that gives a display alarm by lighting or blinking, or a voice generating device that gives a voice call alert. When the microcomputer 106 determines that there is a gas leak, it outputs an alarm signal to the alarm notification unit 107 to prompt recovery.

The microcomputer 106 further includes
A solar cell 108, which serves as a power source of this device, is connected.
As the power source, a commercial power source, a battery, or the like can be used, but since the main body portion including the microcomputer 106 of this device can be installed on the outer wall surface of the house,
In this case, it is preferable to drive the solar cell 108. The solar cell 108 may be used in combination with a battery or a commercial power source.

The microcomputer 106 is connected to a telephone line via a communication controller 300 for controlling switching with a telephone, and further connected via a switch 400 to a host computer 501 installed in an automatic meter reading center 500. Connected and microcomputer 10
When a gas leak is detected in 6, the host computer 501 is notified of that fact.

Further, returning to FIG. 1 and continuing the description, the check valve 200 is disposed in the vicinity of the main branch pipe 11, and by this check valve 200, the pressure on the main branch pipe 11 side at the time of leak detection is detected. It is designed to suppress the effects of fluctuations.
That is, when the pressure fluctuation in the main branch pipe 11, particularly the pressure on the main branch pipe 11 side with respect to the supply pipe 12, decreases,
Because of this, a backflow is generated in the supply pipe 12, so that this is not erroneously recognized as a backflow due to leakage. Note that a check valve or the like having a similar function may be used instead of the check valve 200.

FIG. 3 is a block diagram showing the configuration of the microcomputer 106 constituting the control section of the apparatus main body 100 and its peripherals. As shown in this figure, the microcomputer 106 includes a CPU (Central Processing Unit) 106
0, ROM (Read Only Memory) 1061, RA
An M (random access memory) 1062, a clock 1063 for clocking, and an input / output port 1064 are provided,
These are connected to each other by a bus 1065.
The flow rate sensors 102 and 103 are connected to the input / output port 1064.
A pressure sensor 104, 105, a valve drive circuit 101a for driving the shutoff valve 101, and an automatic meter reading center 5
A communication circuit 108 for notifying the host computer 501 in 00 that there is a gas leak and a notifying section drive circuit 107a for driving the alarm notifying section 107 are connected to each other. In this microcomputer 106,
The CPU 1060 executes the programs stored in the ROM 1061 by using the RAM 1062 as a working area, thereby realizing the functions of the backflow detecting unit and the leak detecting unit.

Next, the operation of this leak detection device will be described with reference to the flow chart shown in FIG.

First, in the normal state, the shutoff valve 101 is in the open state, and the gas supplied from the main branch pipe 11 is supplied to the supply pipe 1.
Gas meters A _{1 to} A ₄ and B _{1 to} B ₄ installed in the house are supplied to the gas meters 2, 12A and 12B, respectively.
Further, the backflow detection frequency value in the microcomputer 106 is set to zero.

In this state, in the apparatus main body 100 installed on the ground portion of the supply pipe 12A, the microcomputer 1
The gas flow rate detected by the flow rate sensor 102 is monitored by 06 (step S401). And the supply pipe 1
The gas flow rate within 2A is a predetermined minute flow rate (for example, 300
When the minute flow rate mode of less than 1 liter / hour is entered (step S401; Y), the shutoff valve 101 is closed to shut off the flow path (step S403). As a result, the supply pipe 12A
The gas flow between the first point and the second point is switched from the supply pipe 12A to the backflow detection flow path 13 side.
If the minute flow rate mode is not entered even after the lapse of the predetermined waiting time (step S401; N, 402), the process returns to step S401.

After that, in the apparatus main body 100, the detection result of the pressure sensor 104 is monitored to judge whether or not there is a sharp pressure drop (step S404). When there is no abrupt pressure drop (N), as described above, the upstream supply pipe 12
It is determined that the gas leakage may have occurred in the first step, and it is first determined whether or not the forward flow is generated based on the detection result of the flow rate sensor 103 (step S405). When the forward flow is generated (Y), the process returns to step S404. When the forward flow has not occurred (N), it is subsequently determined whether or not the reverse flow has occurred based on the detection result of the flow rate sensor 103 (step S406), and the pressure sensor 105
It is determined whether or not the pressure fluctuation has occurred based on the detection result of (step S407). When the pressure fluctuation has not occurred (N), it is determined whether the flow rate of the reverse flow is equal to or more than a predetermined amount (step S408). When the flow rate is equal to or more than the predetermined amount (Y), the reverse flow is determined. The detection count value is incremented (+1) (step S410).

When the backflow detection frequency value reaches a predetermined value (step S411; Y), an alarm signal is output (step S412). As a result, the alarm notification unit 1
07 activates and prompts recovery. At the same time, the device body 10
At 0, the automatic meter reading center 50 is connected through the communication circuit 108.
It notifies the host computer 501 of 0 that there is a gas leak.

After that, the microcomputer 107 outputs a valve opening signal to restore the shutoff valve 101, and after a predetermined waiting time (step S414), the process returns to step S401.

If a sharp pressure drop occurs in step S404 (Y), it means that a gas appliance is used on the downstream side, and gas leakage may have occurred in the supply pipe 12 on the upstream side. If not, the process proceeds to step S413, and the shutoff valve 101 is restored. Also,
In step S407, when the pressure fluctuation is occurring (Y), it is determined that the gas leak does not occur in the supply pipe 12 and that the gas appliance is used in the other system B, and similarly. , The flow goes to step S413 to reset the shutoff valve 101. Further, in step S407, even if the pressure fluctuation is not generated (N) and the backflow is generated in the backflow detection flow path 13, if the flow rate is less than the predetermined amount (step S408; N), , The backflow detection frequency value is cleared (step S409), and similarly, the flow proceeds to step S413 to restore the shutoff valve 101.

As described above, in the apparatus main body 100 of the present embodiment, the presence or absence of gas leakage is automatically detected by detecting the occurrence of a backflow of a predetermined amount or more in the backflow detection flow path 13 under the control of the microcomputer 106. Can be detected. Therefore, the conventional manual inspection work becomes unnecessary, and since it is possible to constantly monitor, the safety function is improved. Further, since the occurrence of gas leakage can be automatically notified to the automatic meter reading center 500, it becomes easy to centrally manage a large number of supply pipes 12. Further, in the present embodiment, the gas flow is switched to the side of the reverse flow detection flow path 13 having a small flow path diameter at the time of detection, so the gas leak detection accuracy is greatly improved.

Further, in the apparatus body 100 of this embodiment, only the check valve 200 need be buried in the ground, and the apparatus body 10
Since 0 can be installed on the ground, the amount to be buried is extremely small. In addition, the check valve 200 may not be necessary in some cases, and in such a case, the buried portion is eliminated, and the installation work and maintenance work become extremely easy. Further, even if the check valve 200 is required, no wiring is required between the check valve 200 and the device body 100, and no communication device is required. Since it is good, the installation work is easy.

The present invention has been described with reference to the examples.
The present invention is not limited to the above embodiment, but can be variously modified. For example, in the above embodiment, the apparatus main body 100 is installed only for one system A, but it may be installed for each of a plurality of systems (two systems A and B in the above embodiment). . According to such a configuration, the presence or absence of gas leakage is determined in each system, so that the presence or absence of gas leakage in the supply pipe 12 can be determined more accurately based on these determinations.

Further, in the above embodiment, the pressure sensor 105 as the pressure fluctuation detecting means is used to discriminate the usage state of the gas appliance of the other system and the occurrence of the gas leak. Needless to say, the pressure sensor 105 is unnecessary.

Further, in the above embodiment, between the apparatus main body 100 and the automatic meter reading center 500, the fact is notified to the automatic meter reading center 500 side only when a gas leak occurs. The host computer 501 and the microcomputer 106 may be bidirectionally communicable, and the host computer 501 may instruct a detection start instruction operation or the like. According to such a configuration, it is possible to perform, for example, the leak detection intermittently by the control from the center every arbitrary period, and the power consumption of the power source such as the solar cell 108 can be reduced.

[0040]

As described above, according to the leak detecting device of the present invention, a backflow detecting flow path having a flow path diameter smaller than that of the supply pipe is provided side by side with the supply pipe, and the flow rate of the fluid flowing through the supply pipe is predetermined. The flow rate of the fluid is switched from the supply pipe to the reverse flow detection flow path side when the flow rate becomes smaller than the flow rate of the above, and the occurrence of the reverse flow is detected in this reverse flow detection circuit. Since it is determined that there is a leak in the supply pipe when it occurs, the leak state in the supply pipe can be automatically detected. Therefore, it is possible to eliminate the need for manpower for detection, to constantly monitor the presence or absence of leakage, and to improve the detection accuracy, thereby significantly improving the safety. Further, since the buried portion in the ground is almost or completely eliminated, the installation work and the maintenance work are extremely easy.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a leak detection device according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a device body of the leak detection device of FIG.

3 is a block diagram showing a circuit configuration of a control unit of the leak detection apparatus of FIG. 1 and its peripherals.

FIG. 4 is a flow chart for explaining the operation of the leak detection apparatus of FIG.

[Explanation of symbols]

100 Device Main Body 12, 12A, 12B Supply Pipe 13 Reverse Flow Detection Flow Path 101 Shutoff Valve (Shutoff Means) 102 Flow Rate Sensor (F ₁ ) (First Flow Rate Measurement Means) 103 Flow Rate Sensor (F ₂ ) (Second Flow Rate) Measuring means) 104 Pressure sensor (P ₁ ) (Pressure drop detecting means) 105 Pressure sensor (P ₂ ) (Pressure fluctuation detecting means) 106 Microcomputer 107 Alarm reporting unit 200 Check valve (Pressure fluctuation suppressing means)

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Claims (8)

(57) [Claims] 1. A leak detection device for detecting the presence / absence of leakage of a fluid flowing through a supply pipe installed between a main branch pipe and a customer, which has a predetermined flow path diameter, in the middle of the supply pipe. And a first flow rate measuring means for measuring the flow rate of the fluid flowing through the supply pipe, a blocking means for blocking the fluid flowing through the supply pipe, and a flow path diameter smaller than that of the supply pipe. And a second flow rate measuring means for measuring the flow rate of the fluid flowing through the backflow detecting flow path. And monitoring the detection result of the first flow rate detecting means, and when the flow rate of the fluid flowing through the supply pipe is in a minute flow rate mode below a predetermined flow rate, the blocking means is driven to block the flow path. , The second flow rate detection A backflow detecting means for detecting the occurrence of a backflow of the fluid in the backflow detecting flow path based on the measurement result of the step, and when the backflow is detected by the backflow detecting means, the backflow is equal to or more than a predetermined flow rate, and When the number of times of detection reaches a predetermined value, a leak detection unit that outputs an alarm signal indicating that a leak has occurred in the supply pipe, and an alarm notification that receives an alarm signal from this leakage detection unit and notifies that there is a leak And a means for detecting leakage. 2. The backflow detecting means includes a pressure drop detecting means for detecting a pressure drop state of the fluid at a position downstream of the backflow detecting flow path of the supply pipe, and the pressure drop detecting means steeply detects the pressure drop. 2. The leak detection device according to claim 1, wherein it is determined that a backflow has occurred when no pressure drop is detected and the flow rate is detected by the second flow rate detection means. 3. The leak detection means outputs an alarm signal, the pressure drop detection means detects a steep pressure drop, or the backflow detection means does not detect a backflow of a predetermined amount or more. 3. The leak detection device according to claim 2, wherein each of the shutoff means is returned to open the flow path. 4. The leak detecting means includes pressure fluctuation detecting means for detecting the presence or absence of pressure fluctuation of the fluid at a position upstream of the backflow detecting flow path of the supply pipe. 4. The method according to claim 3, wherein when a pressure fluctuation is not detected by the pressure fluctuation detecting means after a backflow condition is detected, it is determined whether there is a possibility of leakage and whether or not there is a backflow of a predetermined amount or more. Leak detection device. 5. A pressure fluctuation suppressing means for suppressing an influence due to a pressure fluctuation on the main branch side at the time of detecting a leak is provided at a position near the main branch tube in the supply pipe. The leak detection device according to any one of claims 1. 6. The pressure fluctuation detecting means is installed at an inlet portion of any one system of a supply system in which the supply pipe is branched into a plurality of systems and a plurality of gas meters are connected to these systems, respectively. 5. The leakage detection according to claim 4, wherein when the pressure fluctuation is detected by the above, the leakage detection unit determines that there is no possibility of leakage in the supply pipe because the gas is used in another system. apparatus. 7. The pressure fluctuation detecting means is installed at each of inlets of two or more systems of a supply system in which the supply pipe is branched into a plurality of systems, and a plurality of gas meters are connected to these systems, respectively. 5. The leakage according to claim 4, wherein when the pressure fluctuation is detected by the above, the leakage detection means determines that there is no possibility of leakage in the supply pipe because the gas is being used in another system. Detection device. 8. The communication means is further provided, and the communication means is connected to a meter-reading center through a telephone line and configured to notify the meter-reading center of the occurrence of leakage. The leak detection device according to any one of claims 1.