JP3090186B2 - Gas meter with gas leak inspection function - 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 meter having a gas leak inspection function when an abnormality is detected by a seismic sensor or the like and a gas shutoff valve is closed. In particular, the present invention relates to a gas meter capable of shortening an inspection time and realizing a gas leak inspection function capable of detecting a minute gas leak.

[0002]

2. Description of the Related Art When a city gas, a propane gas, or the like is supplied to a consumer through a pipe, a gas meter is provided for each consumer. This gas meter has functions such as measuring and displaying the flow rate of the used gas, and using various sensors to shut off a shutoff electromagnetic valve inserted into a gas pipe when a gas leak or an earthquake occurs. I have. In recent gas meters, a control device including a microcomputer is mounted on a built-in electrical board to realize various control functions.

When an earthquake is detected by a seismic sensor built in the gas meter, an output signal is input to a control device comprising a microcomputer, and a shutoff valve inserted into the gas pipe is closed by a shutoff command signal from the control device. It is supposed to be. This is to prevent so-called tempura fire, and to ensure safety by foreseeing and forcibly shutting off gas leaks in gas pipes if an earthquake or the like occurs. -ing

[0004] Then, when a user or the like instructs to open the shut-off valve, the shut-off valve is once opened, and an inspection is performed to determine whether or not a gas flow exceeding a predetermined flow rate is generated in the piping. Then, if it occurs, the solenoid valve is shut off again. Incidentally, it is requested that the customer close the main plugs of all gas appliances before opening the shut-off valve.

[0005] FIG.
Shown in That is, after the seismic sensor detects an earthquake or a strong shock and the shut-off valve is closed, when a user or the like issues an instruction to open the shut-off valve, the shut-off valve is once opened and returned (step 1). . Then, it is determined whether or not the flow sensor using the reed switch detects a predetermined flow (step 2). The detection of the flow rate is performed for about 2 minutes in the gas meter currently used (step 3).

The reason for this is that the structure of the flow sensor is such that a rotating mechanism having a magnet attached thereto rotates in response to a gas flow, and a reed switch adjacent to the rotating mechanism counts the rotation of the magnet. This is because, in the worst case, the gas flow rate cannot be detected unless the rotation mechanism makes one rotation. Therefore, in order to detect a small amount of gas leakage, it is necessary to check whether there is a signal from the reed switch for a certain time corresponding to the gas leakage. For example, in the case of the currently used No. 5 meter, a gas flow of 1.7 liters is required for one rotation of the rotating mechanism. Therefore, if the monitoring time is assumed to be two minutes, the worst case is 1.7. It is detected when a gas flow of liter / 2 minutes = 51 liter / h is generated. Of course, if the monitoring time is set longer, a smaller amount of gas leakage can be detected, but this leads to a problem that the inspection time becomes longer.

If the gas flow rate is not detected even after 2 minutes have passed, it is determined that there is no gas leakage and the valve is kept open (step 4). Meanwhile, 2
If the gas flow rate is detected within minutes, it is determined that there is a gas leak, and the shutoff valve is closed again (step 5). Such a series of controls is performed by a control device including a microcomputer.

[0008]

However, as described above, even if the shut-off valve is returned, it takes two minutes for the subsequent leak inspection, so that the use of gas is restricted during that time. Therefore, there is a problem that an inspection cannot be performed instantaneously and a return operation cannot be performed like an electric breaker.

Further, since the presence or absence of the gas flow is detected by the flow rate sensor which rotates in accordance with the actual flow of the gas, in the above example, a minute gas leak of 51 liter / h or less is found in the worst case. Sometimes it becomes impossible.

Accordingly, the present invention has been made to solve the above-mentioned problems, and to provide a gas meter having a gas leak inspection function capable of shortening a substantial inspection time and responding instantly like an electric breaker. With the goal.

Another object of the present invention is to solve the above-mentioned problems and to provide a gas meter having a gas leak inspection function capable of detecting a minute gas leak.

[0012]

According to a first aspect of the present invention, there is provided a gas supply pipe having a gas supply pipe for shutting off and opening a gas flow path; A gas pressure detecting means for measuring a pressure in the gas pipe; and a control means for supplying a shutoff command signal or a return command signal to the shutoff means to control the shutoff or opening of the gas flow path. After the shutoff command signal is supplied to the shutoff means and the gas flow path is shut off, the detection pressure from the gas pressure detection means is monitored, and the detection pressure is set to a predetermined value.
When the pressure is higher than the pressure, the presence or absence of the pressure drop of the detected pressure is detected, and when the detected pressure is lower than the predetermined pressure.
Supplies the return command signal and the cutoff command signal at a predetermined time.
Open the gas flow path during the interval to increase the pressure in the gas pipe.
And then detect the presence or absence of the pressure drop of the detected pressure
And, upon receiving an instruction to return the subsequent blocking means, and characterized in that to open the gas flow path to supply the return command signal when the detection of the absence pressure drop had been This is achieved by providing a gas meter that performs

In this way, when a consumer or the like attempts to return the shut-off means, a response can be made instantaneously based on the gas leak detection result. Also, by monitoring the pressure drop by the pressure sensor, it is possible to detect a minute gas leak. Further, when the gas flow path is shut off,
Whether the tool is in use or not in use.
Check for a pressure drop from a state higher than the specified pressure.
To prepare for a subsequent return command.

[0014] According to a second aspect of the present invention, in the first aspect, the control means is configured to detect the detected pressure from the gas pressure detecting means after the gas flow path is shut off. To detect whether the pressure is lower than a predetermined threshold pressure, and then receive a command to return the shut-off means,
The present invention is attained by providing a gas meter which does not supply the return command signal when it is detected that the pressure is lower than the threshold pressure.

By having such a control means, it is possible to prohibit the return of the shut-off valve when the gas pipe is seriously damaged.

[0016]

According to a third aspect of the present invention, there is provided the gas meter according to the first aspect , wherein opening of the gas flow path for the predetermined time is limited to a predetermined number of times. Is achieved by providing

[0018]

According to a fourth aspect of the present invention, in the first or third aspect , the control means includes:
When receiving a command for returning the blocking means of the said gas
Pressure detected by the pressure detection means is higher than the predetermined pressure.
When the detection of low is performed, the return command signal and the cutoff command signal are supplied to open the gas flow path for a predetermined time to increase the pressure in the gas pipe, and the detected pressure is again detected. This is achieved by providing a gas meter characterized by performing monitoring of the gas.

[0020]

[0021]

[0022]

[0023]

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

[Outline of Gas Meter] FIG. 1 is a schematic diagram of a gas meter system. The gas meter main body 10 is connected to a gas pipe 11. A pair of diaphragms for measuring the amount of gas passing through the gas meter are built in, and reciprocate according to the gas flow, and the reciprocation is transmitted to the permanent magnet, and the movement is read by the lead in the flow rate measuring device 13. It is detected by a switch or the like. The number of reciprocating motions detected in this way is integrated and displayed on the counter 12.

A signal of the flow rate from the flow rate measuring device 13 is sent to a control device 14 comprising a microcomputer, and the control device 14 can know the current gas flow value from the number of pulses per unit time. Further, a detection signal is sent to the control device 14 when an earthquake is detected from the seismic sensor 15 or the like or when strong vibration is detected.

In the control device 14, normal use conditions are set in advance. For example, an instantaneous maximum flow rate or a gas flow rate exceeding the maximum duration without a change in the gas flow rate is detected. When the detection signal is input, the control device 14 supplies the shutoff command signal 22 to the drive unit 18 of the shutoff valve to close the shutoff valve 19.
Then, the reason for the interruption is stored as a history in a memory in the control device 14 and displayed on the control unit 17. When the shut-off valve 19 is a two-way type, the return command signal 22 is supplied from the control device 14 as needed, and the gas flow path is opened.

Reference numeral 16 denotes a battery for supplying power to the control device 14 and the like, and reference numeral 20 denotes a cock for the main plug.

FIG. 2 is a schematic configuration diagram of the control device 14 including a microcomputer provided in the gas meter. In the control device 14, an arithmetic unit 141, a random access memory (RAM) 142, a read only memory (ROM) 143, and an interface unit 145 are connected to a common bus 144. The control device 14 having such a structure includes a battery 16, a flow measurement device 13, a seismic sensor 15, shutoff valves (including a drive unit) 18 and 19, and a display unit 17.
Is connected as described above. A voltage checking means 22 for periodically checking the voltage of the battery 16.
Is connected. A control program for performing various controls in response to input signals from the external sensors is stored in the ROM 143, and the value of the external environment where the gas meter is installed is stored in the ROM 143 or the RAM 14.
2 and used for the above control.

[Outline of Gas Leakage Inspection] In the present embodiment, a pressure sensor 21 for detecting gas pressure in a gas pipe is provided. The position of this pressure sensor 21 is
Any location may be used on the downstream side of the shut-off valve 19, but it is preferably provided in the gas meter main body 10. For example, FIG.
As shown in the figure, it is provided at the outlet to the gas pipe 11.

In the embodiment according to the present invention, the gas leak is inspected by using the pressure sensor 21. Conventionally, after an abnormal state is detected and the shutoff valve 19 is closed,
After opening (returning) the shut-off valve 19, a check was made to see if there was a gas flow for two minutes. On the other hand, in the embodiment according to the present invention, the transition of the gas pressure in the pipe 11 is monitored immediately after the shut-off valve 19 is shut off.
The determination result of the presence of gas leak is stored in the AM 142. As a result, when a switch for returning the shut-off valve 19 is turned on, or when the shut-off valve 19 is manually reset, the shut-off valve is checked by referring to the already determined gas leak determination result. Can be instantaneously performed to return to the normal state or to shut off again in the case of manual operation.

Therefore, it is determined instantaneously whether or not the shut-off valve is to be restored from the request for the return of the shut-off valve, so that an instantaneous operation can be performed like an electric breaker. Further, since a drop in gas pressure is detected, it is possible to detect a minute gas leak. Hereinafter, a specific operation flow will be described in detail.

[Operation Flow 1 of Gas Meter] FIG.
A first example of the operation flowchart of the gas meter is shown. In this example, the shut-off valve 19 provided in the gas meter is capable of performing a bidirectional operation of shut-off and return by an instruction signal from the control device 14.

First, the control device 14, which has received a signal indicating that vibration has been detected from the seismic sensor 15 or the like, closes the shutoff valve in response to a shutoff command signal (step 30). Then, immediately after that, the inspection for gas leakage starts. First, initial values required for inspection are set (step 31). For example, an initial value is given to the gas pressure Qo in the pipe, and 1 is given to the index m.

When the shut-off valve 19 is closed, the pressure of the gas downstream thereof changes, for example, as shown in FIG. The gas pressure is plotted on the vertical axis and the time is plotted on the horizontal axis. If the customer closed the gas cock without using gas appliances when the gas was shut off, as shown in (1) of FIG. The gas pressure is initially, for example, 100 to 250 mmH ₂ O, but if there is no gas leakage, then the high pressure is maintained and becomes as shown in FIG. On the other hand, when there is a gas leak, the gas gradually descends as shown in FIG.

Therefore, here, the pressure of the gas is monitored every fixed sampling time, and it is checked whether or not the pressure has dropped.

Returning to FIG. 3, after a sampling time of, for example, 10 seconds has elapsed (step 32), the pressure of the gas downstream of the shut-off valve 19 is monitored (step 33). Then, for example, the pressure at that time is stored in the memory 142 as Qm. Then, after confirming that the pressure Qm is higher than a predetermined threshold pressure value (step 34), (1) in FIG.
It is determined whether there is a pressure drop as shown in FIG. If a pressure drop is detected, it is determined that there is a gas leak, while if no pressure drop is detected, it is determined that there is no gas leak, and the results of those determinations are stored in a memory in the controller 14. 1
42 (steps 38 and 39).

The above-described detection of the pressure drop is continuously performed until the return switch of the shut-off valve is pressed (step 4).
0). Then, when the switch for resetting the shut-off valve is pressed by the user or the like, the result of the gas leak determination is immediately checked in the control device 14 (step 41). The valve is kept closed (step 43). If it is determined that there is no gas leakage, a return command signal is supplied to open the shutoff valve 19 immediately (step 42).

Next, a case will be described in which the consumer opens the gas cock and uses the gas appliance when the shut-off valve 19 is closed upon detection of an abnormality. In that case, shut off valve 1
When 9 is closed, the downstream gas pressure will drop to almost zero. Therefore, it is not possible to monitor the change in the gas pressure as described above. Therefore, if it is detected in step 34 that the pressure is equal to or lower than a low threshold pressure of, for example, 85 mmH ₂ O or lower, it is desirable to open and close the shutoff valve for a short period of time, for example, about 3 seconds (step 35). . By doing so, the gas pressure on the downstream side of the shut-off valve 19 can be once increased as shown in (2) of FIG.

In general, in the case of recent gas appliances, since the extinguishing safety device is provided, when the shut-off valve is closed and the flame of the gas appliance is extinguished, it is detected by a frame rod or the like and the main plug of the gas appliance is detected. Is closed instantly. In that case, as shown in (2) of FIG. 6, the gas pressure once increased is maintained (c in the figure) or decreased (d in the figure) according to the presence or absence of gas leakage. Therefore, the process waits until, for example, about 20 seconds have elapsed (step 36), and monitors the gas pressure again (step 3).
3). Incidentally, assuming that the gas appliance of the consumer goes out and no safety device is provided, the operation of opening / closing the shutoff valve is limited to a predetermined number of times (step 3).
4).

When a drop in gas pressure is detected as shown in FIG. 6 (2), similar to the above,
The determination that there is a gas leak is stored in the memory 142 in the control device 14. Subsequent operations are the same as those described above, and will not be described here.

Further, as shown in (e) of FIG. 6 (2), if the gas pressure immediately drops to near zero even if the gas pressure is once increased, the main plug of the gas appliance on the consumer side is opened as described above. It is conceivable that the gas pipe or the like has been severely damaged. Therefore, in this case, step 3 is performed to determine whether there is a gas leak.
In 7, in the case where the pressure is equal to or lower than the predetermined threshold pressure, it is determined that there is gas leakage. Therefore, if the main valve of the gas appliance is simply kept open, the shut-off valve will not be opened even if the reset switch is pressed until the customer closes the main valve. This can be said to be an operation similar to that of an electric breaker.

[Operation Flow 2 of Gas Meter] Next, FIG.
2 shows a flowchart of the second operation. The same steps as those in the first operation flow are given the same numbers.

In the above-described first operation flow, it is determined that there is a gas leak even when the gas appliance of the customer goes out and the safety device is not provided. The extinguishing safety device closes the main valve of the gas appliance instantly after the shut-off valve is closed, but when there is no extinguishing safety device, the gas appliance main valve needs to be closed by the consumer. In general,
The gas meter usage manual states that when the gas is shut off, the main valves of all gas appliances are closed before the shut-off valves are returned. Therefore,
It is expected that the return switch will be pressed after the customer closes the main valve. However, in that case, the main plug will be closed some time after the shutoff. Typically, all the main cocks are closed just before the return switch of the shut-off valve is pressed.

Accordingly, in the second operation flow, if the result of the gas leak determination is that there is a gas leak in step 41, the valve is opened again for 3 seconds and then closed (step 45). After a waiting time of, for example, 20 seconds (step 46), the first operation flow from steps 31 to 40 is performed.

As a result, a gas leak test can be performed again in a state where the main plug of the gas appliance is completely closed by the consumer, so that a pure gas leak test can be performed. .

[Operation Flow 3 of Gas Meter] FIG. 5 is a flowchart of the third operation. The same steps as those in FIGS. 3 and 4 are given the same numbers. In this example, the shut-off valve 19 is not bidirectional, and only the control in the shut-off direction is performed by the control device 14, and the control is manually performed at the time of return.

Even when a manual return type shut-off valve is used, the method of the present invention for monitoring a drop in gas pressure immediately after the shut-off of the valve is effective. As shown in FIG. 5, the gas pressure is monitored at every predetermined sampling time (step 32) (step 33), and when the pressure drop is detected or when the pressure becomes lower than a predetermined threshold value (for example, 85 mmH ₂ O or less). Is too low, it is determined that there is a gas leak, and the controller 14
Is stored in the memory 142 in the inside. If the pressure remains at a high position, the determination that there is no gas leakage is stored. Then, when the shut-off valve is manually returned by the consumer or the like, the control device 14 starts to store the already stored memory 142.
According to the result of the determination in step (1), whether the open state is maintained (step 52) or the shutoff valve is forcibly closed again (step 53) is performed.

By doing so, it is not necessary to wait 2-3 minutes after the shut-off valve is manually reset as in the prior art.
Can be used like an electric breaker.

[0049]

As described above, according to the present invention, it is detected whether or not the gas pressure has dropped immediately after the shut-off valve has been closed. The result is stored in the memory. Therefore, when the switch for resetting the shut-off valve is pressed, it is instantaneously determined whether or not the reset is permitted. If there is no gas leakage, the shut-off valve can be reset.

In addition, even when the gas appliance is in use when it is shut off, it is possible to effectively cope with it.

Further, since the fluctuation of the pressure value from the pressure sensor is monitored, it is possible to detect a smaller gas leak than before.

Further, when the loss of the gas pipe is large, the gas pressure drops instantaneously. In this case, the absolute value of the gas pressure indicates a predetermined threshold value or less, and this is also detected. Therefore, gas leakage can be detected flexibly in such an aspect.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a gas meter system.

FIG. 2 is a schematic configuration diagram of a control device.

FIG. 3 is an operation flowchart (1) of the gas meter.

FIG. 4 is an operation flowchart (2) of the gas meter.

FIG. 5 is an operation flowchart (3) of the gas meter.

FIG. 6 is a graph showing an example of a change in gas pressure after shutoff.

FIG. 7 is an operation flowchart of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Gas meter main body 11 Gas pipe 14 Control means 19 Cutoff means 21 Pressure detection means

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-116386 (JP, A) JP-A-61-253076 (JP, A) JP-A-62-209300 (JP, A) JP-A-62-209300 215173 (JP, A) JP-A-62-215172 (JP, A) JP-A-55-110824 (JP, A) JP-A-52-116941 (JP, A) JP-A-7-239099 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F23N 5/24 101 F23N 5/18

Claims (4)

(57) [Claims] 1. A shutoff means provided in a gas pipe for shutting off and opening a gas flow path in a gas supply pipe; a gas pressure detecting means for measuring a pressure in a gas pipe downstream of the shutoff means; Control means for supplying a shut-off command signal or a return command signal to the gas flow path so as to shut off or open the gas flow path. After is shut off, monitor the detected pressure from the gas pressure detecting means, if the detected pressure is higher than a predetermined pressure,
The presence or absence of the pressure drop of the detection pressure is detected, and the detection pressure is detected.
Is lower than the predetermined pressure, the return command signal and
Supply a shutoff command signal to open the gas flow path for a predetermined time.
To increase the pressure in the gas pipe, and then
When the presence / absence of the pressure drop is detected and a command to return the shut-off means is received thereafter , if the absence of the pressure drop is detected, the return command signal is supplied to supply the gas flow path. A gas meter characterized by being opened. 2. The control means according to claim 1, wherein said control means monitors the detected pressure from said gas pressure detecting means after said gas flow path is cut off, and detects whether or not said pressure is lower than a predetermined threshold pressure. A gas meter, characterized in that, when a command to return the shut-off means is received thereafter, if the detection is made that the pressure is lower than the threshold pressure, the return command signal is not supplied. 3. The gas meter according to claim 1 , wherein opening of the gas passage for the predetermined time is limited to a predetermined number of times. 4. In any claim 1 or 3, control means, upon receiving a command for returning the blocking means of the said gas
Pressure detected by the pressure detection means is higher than the predetermined pressure.
When the detection of low is performed, the return command signal and the cutoff command signal are supplied to open the gas flow path for a predetermined time to increase the pressure in the gas pipe, and the detected pressure is again detected. A gas meter characterized by performing monitoring.