JPH08114479A - Gas meter - Google Patents

Abstract

PURPOSE: To obtain a gas meter in which gas leak at a very small flow rate can be inspected in a short time. CONSTITUTION: After a gas flow passage cutoff means (a bidirectional valve) 31 has been returned, the gas flow passage cutoff means 31 is driven by a return cutoff means 32, and the gas flow passage is cut off again. In this state, a change in the gas pressure inside the gas flow passage is detected by a gas- pressure detection means 33, the detection result by the gas pressure detection means 33 is monitored by a judgement means 34 for a prescribed time, and it is judged whether the pressure value has been dropped down to a preset value or not. When it is judged by the judgement means 34 that the pressure value has been decreased down to the preset value, it is judged that gas does not leak at all, the gas flow-passage cutoff means 31 is returned again by a recurrent return means 35, and a gas leak inspection is finished.

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 safety shutoff function by a microcomputer.

[0002]

2. Description of the Related Art In recent years, household gas meters have a function of detecting the flow rate of gas passing through them by a flow meter, and when a gas flow rate of a predetermined amount or more is detected or a gas flow rate of a predetermined period or more is detected. In some cases, various types have been developed that have a gas safety shutoff function that drives a gas shutoff valve to close the gas flow path. As a result, gas leaks in the pipes and unnatural gas outflows are detected to prevent accidents and ensure safety.

By the way, when the gas flow path is cut off by such a gas safety cutoff function, a gas leak inspection is carried out and a recovery operation is carried out. When the recovery work is completed, the shutoff valve is returned by the return lever. Then, after the shut-off valve is returned, a situation where the gas is not used for a predetermined time (for example, 2 minutes) (for example, the flow rate is 50 liters /
If less than h) continues, the gas leak inspection is terminated because there is no gas leak on the downstream side from the gas meter. On the other hand, the use of gas is detected within 2 minutes (for example, the flow rate is 50 liter / h).
If the above is done, it is judged that there is still a gas leak due to a construction error or the like, and the gas cutoff valve is driven again to close the gas flow path.

[0004]

However, in such a conventional gas meter, a leak inspection time is long (2 minutes) after the gas cutoff valve is returned, and a gas leak of a minute flow rate of 50 liter / h or less is required. There is a problem that it is difficult to detect.

The present invention has been made in view of the above problems, and an object thereof is to provide a gas meter capable of performing a gas leak inspection of a minute flow rate in a short time and further improving a gas safety cutoff function. is there.

[0006]

The gas meter of the present invention comprises:
A gas flow rate detecting means for detecting a gas flow rate flowing through the gas flow path, a gas flow path interrupting means for interrupting the gas flow path according to the detection result of the gas flow rate detecting means and capable of being electrically restored, and the gas flow After returning the path shutoff means, the return shutoff means for shutting off the gas flow path again, the gas pressure detection means for detecting the fluctuation of the gas pressure in the gas flow path, and the gas flow path shutoff means by the return shutoff means. In a state where the gas flow path is driven again and is blocked, the detection result of the gas pressure detecting means is monitored for a predetermined time, and it is determined whether the pressure fluctuation value has changed to a preset value or more. When there is a change over a preset value, it is judged that there is a gas leak, and when there is no change over a preset value, there is a judgment means for judging that there is no gas leak, and this judgment means judges that there is no gas leak. When the, and a re-returning means for returning said gas flow path blocking means again.

In this gas meter, the gas flow rate detecting means detects the flow rate of the gas flowing through the gas flow path, and the gas flow path blocking means blocks the gas flow path in accordance with the detection result of the gas flow rate detecting means. Then, after the recovery work is performed, when the gas flow path blocking means is restored by the return blocking means, the gas flow path blocking means is driven and the gas flow path is blocked again. In the state where the gas flow path is blocked again, the determination means monitors the detection result of the gas pressure detection means for a predetermined time and determines whether the pressure fluctuation value has changed to a preset value or more, When the fluctuation value has changed by a preset value or more, it is determined that there is a gas leak, and when there is no change by a preset value or more, it is determined that there is no gas leak. When the determination means determines that there is no gas leakage, the re-returning means restores the gas flow path blocking means again, thereby completing the gas leak inspection.

[0008]

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

FIG. 1 shows a schematic configuration of a gas meter according to an embodiment of the present invention. This gas meter 10
Inside the housing 11, a gas pipe 12 for supplying the gas a to a gas appliance (not shown) is arranged. The gas pipe 12 includes a gas shutoff valve 13 for shutting off the gas flow path at the time of abnormality, a gas flow meter 14 for detecting the flow rate of the gas passing through the gas flow path, and a gas in the gas flow path. The pressure sensor 15 for detecting the pressure is arranged in this order. Further, the housing 11 is provided with a control unit 16 for controlling the gas cutoff valve 13 by determining the presence / absence of gas leakage by using the output signals of the gas flow meter 14 and the pressure sensor 15 as inputs.

The gas shutoff valve 13 is constituted by a valve (bidirectional valve) capable of electrically performing both shutoff and restoration. 2 and 3 show this gas cutoff valve (bidirectional valve) 1
3 shows a specific configuration of No. 3. Here, FIG. 2 shows an open state (return state), and FIG. 3 shows a closed state (blocking state). In the following description, the positional relationship between the opening 12a and the gas cutoff valve 13 in the gas flow path in the gas pipe 12 is described with the opening 12a side being the upper side and the gas cutoff valve 13 side being the lower side. .

The gas cutoff valve 13 has a housing 41 made of a magnetic material. This housing 41
Has a small diameter cylindrical shape on the upper side and a large diameter cylindrical shape on the lower side, and the upper end is open and the lower end is closed. A flange portion 42 is provided outside the central portion of the housing 41 in the vertical direction.
Has been fixed. The flange portion 42 is fixed to the main body (housing 11) of the gas meter 10 in FIG. A cylindrical permanent magnet 4 is provided on the upper side of the housing 41.
3 is provided, and a coil 44 serving as an electromagnet is provided below the housing 41. A plunger 45 is axially movably inserted in a hollow portion formed by the permanent magnet 43 and the coil 44. The plunger 45 includes an upper magnetic portion 45 made of a magnetic material.
a and a lower non-magnetic portion 45b formed of a non-magnetic material. The upper end of the plunger 45 projects from the upper end of the housing 41, and the upper end of the plunger 45 can close the opening 12a in FIG.
6 is attached. Further, a spring 47 that biases the rubber valve body 46 upward is provided between the rubber valve body 46 and the flange portion 42.

No current flows through the coil 44 of the gas cutoff valve 13 in normal times. Further, as shown in FIG. 2, the magnetic force of the permanent magnet 43 acts as shown by the arrow 48, the plunger 45 is drawn in, and the opening 12a is opened. As a result, the gas passes through the opening 12a as indicated by the arrow 49. To put the gas shutoff valve 13 into the shutoff state, a current is passed through the coil 44 to generate a magnetic field that cancels the magnetic field generated by the permanent magnet 43, as shown in FIG. The magnetic force generated by the coil 44 is indicated by a dashed arrow 50. Then, the plunger 45 projects by the force of the spring 47, and the opening 12 a is closed by the rubber valve body 46. On the other hand, in order to return the gas cutoff valve 13, a current in the opposite direction to that in the cutoff state is passed through the coil 44 to generate a magnetic field that strengthens the magnetic field by the permanent magnet 43. As a result, the plunger 45 overcomes the force of the spring 47 and is retracted, and as a result, the opening 12a is opened.

FIG. 4 shows a control unit 1 constituting the gas meter 10.
6 is a block diagram showing the configuration of 6 and its surroundings. FIG. As shown in this figure, the control unit 16 includes a CPU (central processing unit) 2
0, ROM (Read Only Memory) 21, RAM
A (random access memory) 22, a clock 23 and an input / output port 24, which are connected to each other by a bus 25.
Connected by. A gas flow meter 14, a pressure sensor 15, and a drive circuit 26 for driving the gas cutoff valve 13 are connected to the input / output port 24. In the control unit 16, the CPU 20 realizes a function as a gas meter by executing a program stored in the ROM 21 with the RAM 22 as a working area.

FIG. 5 shows a functional configuration of the gas meter 10 of this embodiment. That is, this gas meter 10
Is a gas flow rate detecting means 30 for detecting the flow rate of gas flowing through the gas flow path, and a gas flow path blocking means 31 for blocking the gas flow path according to the detection result of the gas flow rate detecting means 30 and capable of being electrically restored. Then, after returning the gas flow path blocking means 31, the return blocking means 32 for blocking the gas flow path again.
In a state in which the gas pressure detecting means 33 for detecting the fluctuation of the gas pressure in the gas flow path and the gas flow path blocking means 31 are driven by the return blocking means 33 to block the gas flow path again,
While monitoring the detection result of the gas pressure detection means 33 for a predetermined time, it is judged whether the pressure fluctuation value has changed to a preset value or more, and when the pressure fluctuation value has changed to a preset value or more, gas leakage If there is no change over a preset value, it is judged that there is no gas leakage, and when this judgment means 34 judges that there is no gas leakage, the gas flow path blocking means 31 is restored again. And re-returning means 35.

The gas flow rate detecting means 30 is a gas flow meter 14,
The gas flow path cutoff means 31 is realized by the gas cutoff valve (bidirectional valve) 13 and the drive circuit 26, and the gas pressure detection means 33 is realized by the pressure sensor 15. Further, the return cutoff unit 32, the determination unit 34, and the re-return unit 35 are realized by the control unit 16, respectively.

FIG. 6 shows the relationship between the elapsed time after the gas flow path blocking means 31 is blocked again by the return blocking means 32 and the pressure in the gas flow channel, where A is the normal time without gas leakage. The state and B show the states at the time of abnormality with the slight gas leakage. As is clear from this figure, the pressure (P0) does not change in the normal state (A), but the pressure decreases with the passage of time in the abnormal state (B) with slight gas leakage. In the gas meter 10 of this embodiment, an appropriate pressure value lower than the normal pressure (P0) at the time when a predetermined time (T1) has elapsed is the reference pressure (P1).
) Is stored in the RAM 22 in advance, and whether or not there is a minute gas leak is determined depending on whether or not the pressure value after re-cutoff has dropped to the reference pressure (P1).

Next, the operation of the gas meter 10 of this embodiment will be described with reference to the flow chart shown in FIG.

The gas flow rate detecting means 30 detects the gas flow rate flowing through the gas flow path, and the gas flow rate detecting means 30
Gas flow path shutoff means (bidirectional valve) 31 according to the detection result of
The gas flow path is blocked by the above, and after the restoration work, the gas flow path blocking means 31 is restored by the return blocking means 32 (step S700) as in the conventional case. In the present embodiment, after that, the return flow blocking unit 32 drives the gas flow channel blocking unit 31 to block the gas flow channel again (step S701). Then, in this state, the gas pressure detecting means 33
The pressure fluctuation in the gas flow path is detected by the determination means 34, the detection result of the gas pressure detection means 33 is monitored for a predetermined time (T1) by the determination means 34 (step S702), and the pressure value further decreases to a preset value (P1). It is determined whether or not (step S703). The pressure value has not decreased to the preset value (P1) by the judgment means 34 (N).
If it is determined that there is no minute gas leak, the re-returning unit 35 resets the gas flow path blocking unit 31 again (step S704). This completes the gas leak inspection.

On the other hand, if the pressure value has dropped below the preset value (P1) (step S703: Y),
The judgment means 34 judges that there is a slight gas leak, and the recovery work is performed again.

As described above, according to the gas meter 10 of this embodiment, the gas flow path blocking means 31 is constituted by the return blocking means 32.
Then, the gas flow path blocking means 31 is driven, the gas flow path is blocked again, the pressure change in this state is directly measured, and the presence or absence of gas leakage is determined according to the pressure fluctuation amount. Therefore, it is possible to accurately perform a gas leak inspection with a minute flow rate in a short time. This further improves the safety function of the gas meter 10.

[0021]

As described above, according to the gas meter of the present invention, after the gas flow path blocking means is restored, the gas flow path blocking means is driven to cut off the gas flow path, and the gas flow is maintained in this state. Since the change in gas pressure in the road is monitored for a predetermined time to determine the presence or absence of gas leakage, it is possible to accurately perform a gas leakage inspection with a minute flow rate in a short time, and the safety function is further improved. Play.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a gas meter according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining the operation of the bidirectional valve in the gas meter of FIG.

FIG. 3 is a cross-sectional view for explaining the operation of the bidirectional valve in the gas meter of FIG.

FIG. 4 is a block diagram showing a configuration of a control unit and its periphery in the gas meter of FIG.

5 is a functional block diagram for explaining the function of the gas meter of FIG. 1. FIG.

6 is a characteristic diagram showing the relationship between the elapsed time and the pressure after the gas flow path is shut off again after the gas shut-off valve of the gas meter of FIG. 1 is restored.

7 is a flow chart for explaining the operation of the gas meter of FIG.

[Explanation of symbols]

 10 Gas Meter 11 Housing 13 Gas Cutoff Valve (Bidirectional Valve) 14 Gas Flowmeter 15 Pressure Sensor 16 Control Section 30 Gas Flow Rate Detection Means 31 Gas Flow Path Blocking Means 32 Return Blocking Means 33 Gas Pressure Detecting Means 34 Judging Means 35 Re-Returning Means

Claims (1)

[Claims] 1. A gas flow rate detecting means for detecting a gas flow rate flowing through a gas flow path, and a gas flow path shutting means capable of shutting off the gas flow path and electrically returning the gas flow path according to a detection result of the gas flow rate detecting means. A reset blocking means for blocking the gas flow path again after the gas flow path blocking means is reset, a gas pressure detecting means for detecting a variation in gas pressure in the gas flow path, and the gas flow path blocking means. While the gas flow passage is shut off again by being driven by the return shutoff means, the detection result of the gas pressure sensing means is monitored for a predetermined time, and it is determined whether the pressure fluctuation value has changed to a preset value or more. When the pressure fluctuation value changes more than a preset value, it is judged that there is a gas leak, and when there is no change more than the preset value, there is a judgment means that judges that there is no gas leakage, and this judgment means When it is determined that there is no will,
A gas meter, comprising: a resetting means for resetting the gas flow path blocking means again.