JPH08114481A - Gas meter - Google Patents

Abstract

PURPOSE: To obtain a gas meter which enhances a gas safe cutoff function by a method wherein gas leak at a very small flow rate can be inspected in a short time. CONSTITUTION: A gas flow passage cutoff means (a bidirectional valve) 31 is returned, and a pipe is filled with gas. After that, the gas flow-passage cutoff means 31 is driven, and the gas flow passage is cut off again. In addition, when a sufficient time has elapsed and a leak exists, the gas flow passage cutoff means 31 is returned again after the gas inside the pipe on the down stream side has been removed sufficiently. In this state, the detection result by a gas flow rate detection means (a flow sensor) 30 is monitored by a judgement means 33 for a prescribed time, and it is judged whether a very small gas leak exists or not by whether a gas flow rate (an integrated flow rate) is larger than a reference value or not. When it is judged that the gas leak exists, the gas flow passage cutoff means 31 is driven by a redriving means 34, and the gas flow passage is cut off again.

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

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:
Gas flow rate detecting means for detecting the gas flow rate flowing through the gas flow path, gas flow path blocking means for blocking the gas flow path in accordance with the detection result of the gas flow rate detecting means, and for resetting the gas flow path blocking means After the gas flow path is filled with gas, the gas flow path cut-off means is driven again to cut off the gas flow path, and the gas flow path cut-off means is restored again after a lapse of a certain time; In the state where the flow path blocking means is restored by the reset blocking means, the detection result of the gas flow rate detecting means is monitored for a predetermined time, and when the gas flow rate is larger than a preset value, it is judged that there is a gas leak. A judgment means for judging that there is no gas leakage when the value is less than or equal to a preset value, and a re-driving means for driving the gas flow path blocking means again when the judgment means judges that there is a gas leakage.

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 (bidirectional valve) blocks the gas flow path in accordance with the detection result of the gas flow rate detecting means. To be done. When the restoration work is performed, in the return blocking means, the gas flow channel blocking means is reset to fill the gas flow channel with gas, and then the gas flow channel blocking means is driven to block the gas flow channel again, After a lapse of a certain time, the gas flow path blocking means is restored again to open the gas flow path. In the determining means, the detection result of the gas flow rate detecting means is monitored for a predetermined time in this state, and when the gas flow rate is larger than a preset value, it is determined that there is a gas leak,
It is judged that there is no gas leakage when it is less than or equal to a preset value.
When the determination unit determines that there is a gas leak, the re-driving unit drives the gas flow passage blocking unit again to shut off the gas flow passage. The detection result of the gas flow rate detecting means may be an integrated flow rate or an instantaneous flow rate.

[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. A gas shutoff valve 13 for shutting off the gas flow path at the time of abnormality and a gas flow meter 14 for detecting the flow rate of the gas passing through the gas flow path are arranged in this gas pipe 12 in this order. . Further, in the housing 11, a control unit 15 for controlling the gas cutoff valve 13 by determining the presence or absence of gas leakage by using the output signal of the gas flow meter 14 as an input is provided.

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. The housing 41 is formed in a cylindrical shape having a small diameter on the upper side and a large diameter on the lower side, and has an open upper end and a closed lower end. Housing 41
A flange portion 42 is fixed to the outside of the central portion in the vertical direction. The flange portion 42 is fixed to the main body (housing 11) of the gas meter 10 in FIG.
A cylindrical permanent magnet 43 is provided on the upper side of the housing 41, and a coil 44 serving as an electromagnet is provided on the lower side of the housing 41. Further, the plunger 4 is placed in the hollow portion formed by the permanent magnet 43 and the coil 44.
5 is inserted so as to be movable in the axial direction. The plunger 45 includes an upper magnetic portion 45a made of a magnetic material,
It has 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.
A rubber valve body 46 capable of closing the opening 12a is attached. Further, the spring 4 for urging the rubber valve body 46 upward is provided between the rubber valve body 46 and the flange portion 42.
7 are provided.

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 force of the spring 47 causes the plunger 45 to project, and the rubber valve element 46 closes the opening 12a. 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. This allows the plunger 45
Overcomes the force of spring 47 and is retracted, resulting in opening of opening 12a.

As the gas flow meter 14, for example, a thermal type flow velocity sensor (hereinafter referred to as a flow sensor) suitable for measuring a minute flow rate is used. This flow sensor is a sensor that obtains the flow velocity by utilizing the fact that the movement of heat in the pipe is related to the flow velocity of the fluid flowing in the pipe.

FIG. 4 shows a control unit 1 constituting the gas meter 10.
FIG. 5 is a block diagram showing the configuration of 5 and its surroundings. As shown in this figure, the control unit 15 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 and a drive circuit 26 for driving the gas cutoff valve 13 are connected to the input / output port 24. In the control unit 15, the CPU 2
0 uses the RAM 22 as a working area and the ROM 2
By executing the program stored in No. 1, the function as a gas meter is realized.

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 gas flow rate flowing through the gas flow path, 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 a gas flow path blocking means 31. After the means 31 is returned to fill the gas flow path with gas, the gas flow path blocking means 31 is driven again to shut off the gas flow path, and after a certain period of time elapses (that is, the gas is shut off when there is a leak). In the state where the gas flow path blocking means 31 is restored by the return means 32, the return flow blocking means 32 which restores the gas flow channel blocking means 31 again after the gas in the pipe on the downstream side of the valve 13 has sufficiently escaped), The detection result of the gas flow rate detection means 30 is monitored for a predetermined time, and when the gas flow rate is larger than a preset value, it is determined that there is a gas leak,
A judgment means 33 for judging that there is no gas leakage when it is less than or equal to a preset value, and a re-driving means 34 for driving the gas passage blocking means 31 again when the judgment means 33 judges that there is a gas leakage. ing.

The gas flow rate detecting means 30 is a gas flow rate meter 14,
The gas flow path shutoff means 31 is realized by the gas shutoff valve (bidirectional valve) 13 and the drive circuit 26, respectively. Also,
Return blocking means 32, judgment means 33 and re-driving means 34
Are respectively realized by the control unit 15.

FIG. 6 shows a gas flow path shut-off means (bidirectional valve) 31.
, The elapsed time after being driven by the return blocking means 32, being driven again after the gas flow path was blocked again, and the flow rate detected by the gas flow rate detecting means (flow sensor) 30 (integrated flow rate). A represents a normal state without gas leakage, and B represents an abnormal state with minute gas leakage. As is clear from this figure, the flow rate does not change during normal operation (A). On the other hand, at the time of abnormality (B) with slight gas leakage, when the gas flow path shutoff means (bidirectional valve) 31 is restored again, the upstream side thereof is sufficiently filled with gas. The integrated flow rate increases instantaneously for the first time, and thereafter maintains a substantially constant value. In the gas meter 10 of the present embodiment, an appropriate flow rate between the integrated flow rate in the normal state and the integrated flow rate in the abnormal state at the time when a predetermined time (T1) has elapsed is the reference flow rate (Q1).
Is stored in the RAM 22 in advance, and it is determined whether or not there is a minute gas leak depending on whether or not the integrated flow rate after restoration has reached this reference flow rate (Q1).

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 flow rate of the gas flowing through the gas flow path.
Gas flow path shutoff means (bidirectional valve) 31 according to the detection result of
After the gas flow path is blocked by the above and the recovery work is performed, 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, thereafter, after the gas flow path is filled with gas (step S701), the return cut-off means 32 drives the gas flow path cut-off means 31 to cut off the gas flow path again (step S702). After a further sufficient time has passed (that is, after the gas in the pipe on the downstream side of the gas cutoff valve 13 has sufficiently escaped if there is a leak), the gas flow path cutoff means 31 is restored again (step S703). ).

Then, in this return state, the flow rate is detected by the gas flow rate detection means 30, and the detection result of the gas flow rate detection means 30 is determined by the determination means 33 for a predetermined time (T).
1) Monitored (step S704). Then, in the judging means 33, the gas flow rate (integrated flow rate) is calculated as the reference flow rate (Q1).
When it is larger than the above, it is judged that there is a gas leak, and when it is below the reference flow rate (Q1), it is judged that there is no gas leak (step S705). When the determination means 33 determines that there is a gas leak (step S705; Y), the re-driving means 34 drives the gas flow path blocking means 31 to block the gas flow path again (step S706). After that, recovery work is performed again.

On the other hand, when the determination means 33 determines that there is no gas leakage (step S705; N), the return state of the gas flow path blocking means 31 is left as it is, and the gas leakage inspection is completed.

As described above, in the gas meter 10 of this embodiment, after the restoration work is performed, the gas flow path shutoff means (bidirectional valve) 31 is restored by the return shutoff means 32,
After the gas flow path is filled with gas, the gas flow path blocking means 31
To shut off the gas flow path again, and after a sufficient time has elapsed (that is, if there is a leak, the gas shutoff valve 1
The gas flow path blocking means 31 is restored again after the gas in the pipe on the downstream side of 3 is sufficiently released. Therefore, when there is a gas leak, there is a considerable flow rate instantaneously flowing through the gas flow path, and by detecting this flow rate, the gas flow rate detecting means (gas flow meter 1 with a small minimum operating flow rate) can be obtained.
Even in the case of 4), it is possible to accurately detect a gas leak with a minute flow rate in a short time. As a result, the gas meter 10
The safety function of is improved.

In the above embodiment, the presence or absence of gas leakage is determined by the integrated flow rate after the lapse of a predetermined time, but the presence or absence of gas leakage may be determined by comparing the instantaneous flow rate with a predetermined value. May be.

[0024]

As described above, according to the gas meter of the present invention, when the restoration work is performed, the gas flow path blocking means is restored to fill the gas flow path with the gas, and then the gas flow path blocking means is provided. To shut off the gas flow path again and after a certain period of time, restart the gas flow path shutoff means, and in this state, monitor the detection result of the gas flow rate detection means for a predetermined time, and the gas flow rate is set to a preset value. It is judged that there is a gas leak when it is larger than the above, it is judged that there is no gas leak when it is less than or equal to a preset value, and when it is judged that there is a gas leak, the gas flow path is cut off again, so it is possible to shorten the time. In addition, it is possible to perform a gas leak inspection with a small flow rate with high accuracy, and to further improve the safety function.

[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 a gas cutoff valve (bidirectional valve) in the gas meter of FIG.

FIG. 3 is a cross-sectional view for explaining the operation of a gas cutoff valve (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 showing a functional configuration of the gas meter of FIG.

FIG. 6 is a characteristic diagram showing a relationship between an elapsed time after the gas cutoff valve of the gas meter of FIG. 1 is restored again and an integrated flow rate.

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

[Explanation of symbols]

 10 Gas Meter 11 Housing 12 Gas Pipe 13 Gas Cutoff Valve (Bidirectional Valve) 14 Gas Flowmeter 15 Control Section 30 Gas Flow Rate Detection Means (Flow Sensor) 31 Gas Flow Path Blocking Means (Bidirectional Valve) 32 Return Blocking Means 33 Judgment Means 34 Re-driving means

Claims (1)

[Claims] 1. A gas flow rate detecting means for detecting a gas flow rate flowing through the gas flow path, a gas flow path blocking means for blocking the gas flow path according to a detection result of the gas flow rate detecting means, and the gas flow path blocking means. After returning the means to fill the gas flow path with gas, the gas flow path interrupting means is driven again to interrupt the gas flow path, and the gas flow path interrupting means is restarted after a certain time has passed. Means, and the gas flow path blocking means is returned by the return blocking means, while monitoring the detection result of the gas flow rate detection means for a predetermined time, when the gas flow rate is larger than a preset value Judgment means for judging that there is a leak, and judging that there is no gas leak when it is less than or equal to a preset value, and a re-driving hand for re-driving the gas flow path blocking means when it is judged by this judgment means that there is a gas leak. Gas meter, characterized in that it comprises and.