JPH09145053A - Gas meter having gas leakage inspection function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect fine gas leakage in a short time by monitoring detected pressure from gas pressure detection means to detect the presence of predetermined pressure drop when a gas flow passage is interrupted with interruption means, and when no pressure drop is detected, returning the interruption means to open the gas flow passage. SOLUTION: When a signal informing a user of a fact that vibration is detected by a vibration sensitive sensor 15 is received, an interruption valve 19 is closed by a signal from a controller 14. Just after it, gas leakage inspection is started, and an intial value required for the inspection is first set. Then, a pressure sensor 21 is used to monitor a change in gas pressure in a piping 11 just after the interruption valve 21 is interrupted, and when there is pressure drop, a judgement of the presence of gas leakage is stored in a RAM in the controller 14. When a switch requiring the return of the interruption valve 19 is on or when the interruption valve 19 is returned by manual, reference is made to the judgement result of the gas leakage whereby there is instantaneously performed an operation of whether the interruption valve 19 is returned or is again interrupted.

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 the gas cutoff valve is closed. In particular, the present invention relates to a gas meter capable of shortening an inspection time and realizing a gas leakage inspection function capable of detecting a minute gas leakage.

[0002]

2. Description of the Related Art When supplying city gas, propane gas or the like to a customer through piping, a gas meter is provided for each customer. This gas meter has the functions of measuring and displaying the flow rate of the used gas, and also using various sensors to shut off the shutoff solenoid valve inserted in the gas pipe when a gas leak or an earthquake occurs. There is. Further, recent gas meters are equipped with a control device composed of a microcomputer on a built-in electrical board to realize various control functions.

When an earthquake is detected by the seismic sensor incorporated in the gas meter, the output signal is input to the control device composed of a microcomputer, and the shutoff valve inserted in the gas pipe is closed by the shutoff command signal from the control device. It is designed to be used. This is to prevent the so-called tempura fire and to prevent gas leaks in the gas pipes in the event of an earthquake, etc. -ing

Then, when the customer or the like subsequently gives an instruction operation to open the shutoff valve, once the shutoff valve is opened, it is inspected whether a gas flow exceeding a predetermined flow rate is generated in the pipe. If it occurs, the solenoid valve is shut off again. Note that consumers and the like are required to close all gas appliances before opening the shutoff valves.

FIG. 7 is a flow chart showing the above specific operation.
Shown in That is, after the seismic sensor detects an earthquake or a strong shock and the shutoff valve is closed, when the customer or the like issues an instruction to open the shutoff valve, the shutoff valve is once opened to restore it (step 1). . Then, it is judged whether or not the flow rate sensor using the reed switch detects a predetermined flow rate (step 2). The gas flow meter currently in use detects the flow rate for about 2 minutes (step 3).

The reason for this is that the structure of the flow rate sensor is such that the rotating mechanism to which the magnet is attached rotates in response to the gas flow, and the 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 rotating 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 period of time commensurate with it. For example, in the case of the currently used No. 5 meter, 1.7 liters of gas flow is required for one rotation of the rotating mechanism, so if the monitoring time is 2 minutes, the worst case is 1.7. It will be detected when a gas flow of liter / 2 minutes = 51 liter / h is generated. Of course, if a long monitoring time is set, it is possible to detect a smaller amount of gas leakage, but this causes a problem that the inspection time becomes longer.

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

[0008]

However, as described above, even if the shut-off valve is restored, it takes two minutes for the subsequent leak inspection, and the use of gas is restricted during that time. Therefore, there is a problem that it is impossible to perform an inspection in an instant like an electric breaker and react to the return operation.

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.

Therefore, the present invention solves the above-mentioned problems, and provides a gas meter having a gas leak inspection function capable of shortening the substantial inspection time and being able to respond instantly like an electric breaker. With the goal.

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

[0012]

According to the first aspect of the present invention, the above object is to provide a shutoff means provided in a gas pipe for shutting and opening a gas flow passage in a gas supply pipe, and a shutoff means downstream of the shutoff means. The control means has a gas pressure detection means for measuring the 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 shut off or open the gas flow path. Supplies a shutoff command signal to the shutoff means to shut off the gas flow path, monitors the detected pressure from the gas pressure detection means to detect the presence or absence of a predetermined pressure drop, and then shuts off the shutoff means. To provide a gas meter, characterized in that, when it is detected that there is no pressure drop when receiving a command to restore, the restore command signal is supplied to open a gas flow path. Achieved by

By doing so, when a consumer or the like tries to restore the shutoff means, it is possible to respond instantly based on the gas leak detection result. Further, by monitoring the pressure drop by the pressure sensor, it becomes possible to detect a minute gas leak.

According to the second aspect of the present invention, there is provided the control means according to the first aspect, wherein the control means detects the pressure detected by the gas pressure detecting means after the gas flow path is blocked. Is detected to detect whether or not the pressure is lower than a predetermined threshold pressure, and then, when a command to return the breaking means is received,
This is achieved by providing a gas meter characterized in that the return command signal is not supplied when it is detected that the pressure is lower than the threshold pressure.

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

According to the third aspect of the invention, there is provided the control means according to the first or second aspect of the invention, wherein the control means operates from the gas pressure detecting means after the gas flow path is blocked. If the detected pressure is lower than a predetermined pressure, 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 then the detected pressure. It is achieved by providing a gas meter characterized in that

Further, according to the fourth aspect of the present invention, the gas meter according to the third aspect is characterized in that the opening of the gas flow path during the predetermined time is restricted within a predetermined number of times. Is achieved by providing.

According to the third and fourth aspects of the present invention, even if the gas appliance is in use when it is shut off, it is possible to raise the pressure in the gas pipe once and then monitor the pressure drop.

According to a fifth aspect of the invention, there is provided the above-mentioned first to fourth aspects of the invention, wherein the control means is
When it is detected that the pressure is lower than the threshold pressure when the command to restore the shutoff means is received, the restoration command signal and the shutoff command signal are supplied to the gas flow for a predetermined time. It is achieved by providing a gas meter characterized by opening a passage to increase the pressure in the gas pipe and again monitoring the detected pressure.

Further, according to the sixth aspect of the present invention, there is provided a shutoff means provided in the gas pipe for shutting off the gas flow passage in the gas supply pipe, and a pressure in the gas pipe downstream of the shutoff means. And a control means for supplying a shutoff command signal to the shutoff means to control the shutoff of the gas flow path, and the control means sends the shutoff command signal to the shutoff means. After the gas is supplied and the gas flow path is cut off, the pressure detected by the gas pressure detection means is monitored to detect the presence or absence of a predetermined pressure drop, and when the cut-off means is restored thereafter, the pressure drop is This can be achieved by providing a gas meter characterized by supplying the shutoff command signal to shut off the gas flow path again when it is detected that the gas meter is present.

Further, according to the seventh invention, in the sixth invention, the control means is configured to detect the pressure detected by the gas pressure detection means after the gas flow passage is blocked. Is detected to detect whether the pressure is lower than a predetermined threshold pressure, and then, when the cutoff means is restored, if it is detected that the pressure is lower than the threshold pressure, the cutoff command signal is supplied. This is achieved by providing a gas meter characterized in that the gas flow path is again blocked.

According to the sixth and seventh aspects of the invention, it is possible to detect a gas leak in a short time even when using a manually return type shutoff valve.

[0023]

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

[Outline of Gas Meter] FIG. 1 is a schematic view of a gas meter system. The gas meter body 10 is connected to the gas pipe 11. A pair of diaphragms for measuring the amount of gas passing through the gas meter are built-in, reciprocate according to the gas flow, the reciprocating motion is transmitted to the permanent magnet, and the motion is 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.

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

In the control device 14, the normal use condition is set in advance, and for example, the instantaneous maximum flow rate or the gas flow rate exceeding the maximum duration without change of the gas flow rate is detected, or the seismic sensor 15 is used. When the detection signal is input, the control device 14 supplies the shutoff valve drive unit 18 with the shutoff command signal 22 to close the shutoff valve 19.
Then, the reason for the interruption is stored as a history in the memory in the control device 14 and displayed on the control unit 17. When the shutoff valve 19 is of a bidirectional type, the controller 14 supplies a return command signal 22 as necessary to open the gas flow path.

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

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 rate measuring device 13, a seismic sensor 15, shut-off valves (including drive units) 18, 19 and a display unit 17.
Are connected as described above. In addition, voltage check means 22 for regularly checking the voltage of the battery 16
Is connected. Then, a control program for performing various controls in response to the input signals from the external sensors is stored in the ROM 143, and the value of the external environment in which the gas meter is installed is the ROM 143 or the RAM 14
2 and is used for the above control.

[Outline of Gas Leakage Inspection] In the present embodiment, a pressure sensor 21 for detecting the gas pressure in the gas pipe is provided. The position of this pressure sensor 21 is
It may be provided anywhere on the downstream side of the shutoff valve 19, but it is preferably provided in the gas meter main body 10. For example, FIG.
As shown in FIG. 5, it is provided at the exit portion to the gas pipe 11.

In the embodiment according to the present invention, the gas sensor is inspected for a gas leak. Conventionally, after an abnormal state is detected and the shutoff valve 19 is closed,
After the shutoff valve 19 was opened (reset), it was examined whether or not there was a gas flow for 2 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 shutoff valve 19 is shut off.
The determination result of gas leak is stored in the AM 142. As a result, when the switch for restoring the shutoff valve 19 is turned on, or when the shutoff valve 19 is manually restored, the shutoff valve is checked by referring to the gas leak determination result that has already been inspected. It is possible to instantaneously perform the operation of returning to the above or shutting off again in the case of manual operation.

Therefore, whether or not the return is possible is instantly judged from the request for the return of the shut-off valve, and the instant operation like an electric breaker becomes possible. Further, since the decrease 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 a gas flow chart is shown. In this example, as the shutoff valve 19 provided in the gas meter, a shutoff valve 19 that can perform a bidirectional operation of shutoff and return in response to an instruction signal from the control device 14 is used.

First, the control device 14, which has received a signal from the seismic sensor 15 or the like indicating that a vibration has been detected, closes the shutoff valve in response to a shutoff command signal (step 30). Immediately after that, the gas leak inspection starts. First, an initial value required for inspection is 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 shutoff valve 19 is closed, the pressure of the gas on the downstream side thereof changes, for example, as shown in FIG. The vertical axis shows the gas pressure and the horizontal axis shows the time, but if the customer side closed the gas plug without using the gas appliance when the gas was cut off, as shown in (1) of FIG. The gas pressure is, for example, 100 to 250 mmH ₂ O at first, whereas when no gas leaks, the high pressure is maintained thereafter, as shown by a in the figure. On the other hand, if there is a gas leak, then it will gradually fall as indicated by b in the figure.

Therefore, here, the gas pressure is monitored at regular sampling intervals to check whether or not the gas pressure has dropped.

Returning to FIG. 3, for example, after the sampling time of 10 seconds has elapsed (step 32), the gas pressure downstream of the shutoff 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.
A determination is made as to whether there is a pressure drop as shown in (step 37). Then, 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 these determinations are stored in the memory in the control device 14. 1
It is stored in 42 (steps 38, 39).

The above pressure drop is continuously detected until the return switch of the shutoff valve is pressed (step 4).
0). When the user presses the switch for shutting off the valve, the control device 14 immediately checks the gas leak determination result (step 41), and if it is determined that there is a gas leak, shuts off regardless of the reset switch. The valve is kept closed (step 43). If it is determined that there is no gas leakage, a return command signal is immediately supplied to open the shutoff valve 19 (step 42).

Next, a case will be described in which, when an abnormality is detected and the shutoff valve 19 is closed, the consumer side uses the gas appliance by opening the gas plug. In that case, shut-off valve 1
When 9 is closed, the gas pressure on the downstream side will drop to almost zero. Therefore, the change in gas pressure cannot be monitored as described above. Therefore, if it is detected in step 34 that the pressure is lower than a low threshold pressure of, for example, 85 mmH ₂ O or less, it is desirable to open the shutoff valve once for a short time of, for example, 3 seconds and then close it (step 35) . By doing so, as shown in (2) of FIG. 6, the gas pressure on the downstream side of the shutoff valve 19 can be temporarily increased.

Generally, in the case of recent gas appliances, since a safety device for extinguishing the gas is installed, when the shutoff 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. Can be closed instantly. In that case, as shown in (2) of FIG. 6, the once increased gas pressure is maintained (c in the figure) or dropped (d in the figure) depending on the presence or absence of gas leakage. Therefore, the gas pressure is monitored again, for example, after waiting for about 20 seconds (step 36).
3). Assuming that the gas appliance of the consumer is not equipped with a safety device for extinguishing the gas, 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 (2) of FIG. 6, 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 are omitted here.

Further, as shown in (e) of FIG. 6 (2), when the gas pressure immediately rises 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 it has been left as it is, or that the gas pipe or the like has been severely damaged. Therefore, in that case also, in order to determine whether there is a gas leak, step 3
In No. 7, even when the pressure is equal to or lower than the predetermined threshold pressure, it is determined that the gas is leaked. Therefore, if the main valve of the gas appliance is simply left open, the shutoff valve will not be opened even if the return switch is pressed until the customer closes the main valve. This point can be said to be the same as that of an electric breaker.

[Operation flow 2 of gas meter] Next, referring to FIG.
Shows the flowchart of the second operation. The same numbers are attached to the same steps as those in the first operation flow.

In the first operation flow described above, it is determined that there is a gas leak even if the gas appliance of the consumer is not equipped with a safety device for extinguishing the gas. The extinguishing safety device closes the main plug of the gas appliance immediately after the shutoff valve is closed, but without the extinguishing safety device, it is necessary for the consumer to close the main plug of the gas appliance. In general,
The instruction manual of the gas meter explains that when the gas is shut off, the main valves of all the gas appliances are closed and then the shutoff valves are restored. Therefore,
It is expected that the consumer will close the main valve and then press the return switch. However, in that case, the main plug will be closed some time after the interruption. Typically, all plugs are closed immediately before the return switch of the shutoff valve is pressed.

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

As a result, the customer can perform the gas leak test again with all the main taps of the gas appliance closed, so that it is possible to purely check whether or not the gas leak has occurred. .

[Gas Meter Operation Flow 3] FIG. 5 shows a flowchart of the third operation. The same steps as those in FIGS. 3 and 4 are denoted by the same numbers. In this example, the shutoff valve 19 is not bidirectional, and only the shutoff direction is controlled by the control device 14, and the shutoff valve 19 is manually restored at the time of restoration.

Even when a manual return type shutoff valve is used, the method of monitoring the gas pressure drop immediately after the valve of the present invention shuts off is effective. As shown in FIG. 5, the gas pressure is monitored every predetermined sampling time (step 32) (step 33), and when a pressure drop is detected or the pressure is below a predetermined threshold value (for example, 85 mmH ₂ O or less). If is also low, it is determined that there is a gas leak, and the control device 14
It is stored in the internal memory 142. When the pressure remains high, the determination that there is no gas leak is stored. Then, when the shut-off valve is manually restored by the user or the like, the control device 14 stores the already-stored memory 142.
Depending on the result of the determination, the open state is maintained (step 52) or the shutoff valve is forcibly closed again (step 53).

By doing so, it is not necessary to wait 2-3 minutes as in the conventional case after manually returning the shutoff valve.
Can be used like an electric breaker.

[0049]

As described above, according to the present invention, it is detected whether or not there is a gas pressure drop immediately after the shutoff valve is closed, and if there is a pressure drop, it is determined beforehand that there is a gas leak. The result is stored in memory. Therefore, when the switch for resetting the shutoff valve is pressed, it is instantly judged whether or not the restoration is allowed, and the shutoff valve can be restored if there is no gas leakage.

Further, even when the gas appliance is in use when it is shut off, it can be effectively dealt with.

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

Further, when the loss in the gas pipe is great, the gas pressure drops instantaneously. In that case, the absolute value of the gas pressure shows a value equal to or lower than a predetermined threshold value, and it should be detected. Therefore, it is possible to flexibly deal with such an aspect and detect a gas leak.

[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 changes in gas pressure after interruption.

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

[Explanation of symbols]

 10 gas meter main body 11 gas pipe 14 control means 19 shut-off means 21 pressure detection means

Claims (7)

[Claims] 1. A shutoff means provided in the gas pipe for shutting and opening a gas flow passage in a gas supply pipe, a gas pressure detecting means for measuring the pressure in the gas pipe downstream of the shutoff means, and the shutoff means. And a control means for controlling to shut off or open the gas flow path by supplying a shutoff command signal or a return command signal to the gas flow path. Is detected, the pressure detected by the gas pressure detection means is monitored to detect the presence or absence of a predetermined pressure drop, and when a command to restore the cutoff means is received thereafter, it is detected that there is no pressure drop. The gas meter is configured to supply the return command signal to open the gas flow path when the gas meter has been operated. 2. The control means according to claim 1, wherein the pressure detected by the gas pressure detecting means is monitored after the gas flow path is blocked to detect whether the pressure is lower than a predetermined threshold pressure. The gas meter is configured not to supply the return command signal when it is detected that the pressure is lower than the threshold pressure when the command for returning the cutoff unit is received thereafter. 3. The return command signal according to claim 1, wherein the control means, when the pressure detected by the gas pressure detecting means is lower than a predetermined pressure after the gas flow path is blocked. And a cutoff command signal are supplied to open the gas flow path for a predetermined time to increase the pressure in the gas pipe, and then monitor the detected pressure. 4. The gas meter according to claim 3, wherein the opening of the gas flow path during the predetermined time is restricted within a predetermined number of times. 5. The control means according to claim 1, wherein when the control means detects that the pressure is lower than the threshold pressure when receiving a command to restore the shutoff means, A gas meter, wherein the return command signal and the shutoff command signal are supplied, the gas flow path is opened for a predetermined time to increase the pressure in the gas pipe, and the detected pressure is monitored again. 6. A shutoff means provided in the gas pipe for shutting off a gas flow passage in the gas supply pipe, a gas pressure detection means for measuring a pressure in the gas pipe downstream of the shutoff means, and the shutoff means. And a control means for controlling to cut off the gas flow path by supplying a cutoff command signal, the control means supplying a cutoff command signal to the cutoff means to cut off the gas flow path, The pressure detected by the gas pressure detection means is monitored to detect the presence or absence of a predetermined pressure drop, and when the shutoff means is restored thereafter, if the presence of the pressure drop is detected, the shutoff is performed. A gas meter characterized by supplying a command signal to interrupt the gas flow path again. 7. The control means according to claim 6, wherein the pressure detected by the gas pressure detecting means is monitored after the gas flow path is blocked to detect whether the pressure is lower than a predetermined threshold pressure. Then, when it is detected that the pressure is lower than the threshold pressure when the shutoff means is restored thereafter, the shutoff command signal is supplied to shut off the gas flow path again. Gas meter.