JP3380348B2 - Gas meter - 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 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 devices having a so-called safety function of driving a gas cutoff valve to close the gas flow path have been developed. 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]

A gas meter according to claim 1 is a gas flow rate detecting means for detecting a gas flow rate flowing through a gas flow path, and is arranged upstream of the gas flow rate detecting means .
A gas flow path blocking means capable of electrically returning and blocking the gas flow path in accordance with the detection result of the gas flow rate detection means ,
After returning the gas flow path blocking means, the gas flow path blocking means is driven to block the gas flow path, and after a lapse of a certain time, a return blocking means for resetting the gas flow path blocking means again, The rate of change of the gas flow rate that can be detected by the gas flow rate detecting unit is stored in a plurality of stages in accordance with the magnitude thereof, and the magnitude of the rate of flow rate change corresponds to each of the distinguished flow rate change rates. The detection result of the gas flow rate detection means is monitored in a state in which the storage means stores a plurality of inspection times having a size inversely proportional to the above At the same time, the flow rate change rate is obtained, and the range of the flow rate change rate stored in the storage means is distinguished, and further, after the gas flow path blocking means is restored again. , That range It is judged whether the flow rate fluctuation value within the inspection time is within a predetermined reference value. If the flow rate fluctuation value is larger than the reference value, it is judged that there is a gas leak, and if it is within the reference value, there is no gas leak. And a re-interruption means for reactivating the gas flow path interruption means to interrupt the gas flow path when the decision means judges that there is a gas leak.

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 flow rate detection means and obtains the flow rate change rate, and the flow rate change rate is the flow rate change rate stored in advance in the storage means. Distinguish which range is applicable. Further, after the gas flow path blocking means is restored again, the determining means determines the inspection time corresponding to the range (that is, a short inspection time when the flow rate change rate is large, and a long inspection time when the flow rate change rate is small. It is determined whether the flow rate fluctuation value within (time) is within a predetermined reference value. When the flow rate fluctuation value is larger than the reference value, it is determined that there is gas leakage, and when it is within the reference value, it is determined that there is no gas leakage. When the determination unit determines that there is a gas leak, the re-cutoff unit drives the gas flow path cutoff unit again to cut off the gas flow path.

A gas meter according to a second aspect is the gas meter according to the first aspect, in place of the re-cutoff means,
When the judging means judges that there is a gas leak, an alarm notifying means for notifying the fact is provided.

A gas meter according to a third aspect is the gas meter according to any one of the first and second aspects, wherein the reference value of the flow rate fluctuation is set to be constant regardless of the magnitude of the flow rate change rate, and the judgment means is The same reference value is used to determine the presence or absence of gas leakage regardless of the magnitude of the flow rate change rate.

A gas meter according to a fourth aspect is the gas meter according to any one of the first and second aspects, wherein the reference value of the flow rate fluctuation is set in a plurality of stages according to the magnitude of the flow rate change rate, and the determination means is The presence or absence of gas leakage is determined using different reference values according to the magnitude of the flow rate change rate.

[0011]

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. There is. 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 shutting off and returning. 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 shutoff 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.
Is 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. 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. Plunger 4
5 has an upper magnetic part 45a made of a magnetic material and a lower non-magnetic part 45b made of a non-magnetic material. The upper end of the plunger 45 projects from the upper end of the housing 41, and a rubber valve body 46 capable of closing the opening 12a in FIG. 1 is attached to the upper end of the plunger 45. A spring 47 for urging 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 force of the spring 47 causes the plunger 45 to project, and the rubber valve element 46 closes the opening 12 a. 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.
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. The gas meter 10 includes a gas flow rate detecting means 30 for detecting a gas flow rate flowing through a gas flow path,
According to the detection result of the gas flow rate detecting means 30, the gas flow path is blocked and the gas flow path blocking means 31 is capable of being electrically restored, and after the gas flow path blocking means 31 is reset, the gas flow path is blocked. The means 31 is driven to shut off the gas flow path, and after a certain period of time, the return flow blocking means 32 for returning the gas flow path blocking means 31 again and the rate of change of the gas flow rate detectable by the gas flow rate detection means 30 ( Flow rate fluctuation amount for each predetermined time)
Are stored in a plurality of stages according to their magnitudes, and a plurality of inspection times having a size inversely proportional to the magnitude of the flow rate change rate are stored corresponding to each of the distinguished flow rate change rates. The storage means 33 and the gas flow path blocking means 31 are driven after the gas flow path blocking means 31 is restored, and the gas flow path is blocked,
The detection result of the gas flow rate detection means 30 is monitored, the flow rate change rate is obtained, and it is distinguished whether the flow rate change rate corresponds to which range of the flow rate change rate stored in the storage means 33.
Further, after the gas flow path blocking means 31 is restored again, it is judged whether or not the flow rate fluctuation value within the inspection time corresponding to the range is within a predetermined reference value, and the flow rate fluctuation value is
When it is larger than the reference value, it is judged that there is a gas leak, and when it is within the reference value, there is a judgment means 34 that judges that there is no gas leak, and when this judgment means 34 judges that there is a gas leak, a gas flow path blocking means. 31 is provided again, and re-interrupting means 35 for interrupting the gas flow path is provided.

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 storage means 33 is realized by the RAM 22. Further, the return cutoff unit 32, the judgment unit 34, and the recutoff unit 35 are realized by the control unit 15.

FIG. 6 shows a gas flow path shut-off means (bidirectional valve) 31.
Is restored by the return cut-off means 32, the gas flow-path cut-off means (bidirectional valve) 31 is driven to cut off the gas flow path, and after a certain period of time elapses, the gas flow-path cut-off means (bidirectional valve)
It shows the relationship between the elapsed time and the gas flow rate integrated value after 31 is restored again. Here, A is a normal state without gas leakage, and B and C are abnormal states with gas leakage. As is clear from this figure, in the normal state (A), the integrated value of the gas flow rate momentarily increases, but thereafter it stabilizes at a constant value. On the other hand, in the abnormal state (B, C) with gas leakage, the flow rate increases momentarily, and then the flow rate gradually increases with the lapse of time.

By the way, the change in the integrated value of the gas flow rate is shown in FIG.
There is also a case where the flow rate changes significantly as shown by B (that is, the flow rate change rate (flow rate change amount at every predetermined time) is large), and a case where the flow rate changes gently as shown by C in FIG. 6 (that is, There is also a small flow rate change rate).

In the gas meter 10 of this embodiment, the gas flow path shut-off means (bidirectional valve) 31 is restored, and the gas flow path shutoff means (bidirectional valve) 31 is driven to shut off the gas flow path. Such a flow rate change rate is calculated. The rate of change in flow rate is stored in the RAM 22 in advance according to its magnitude, for example, in two stages of large and small, and corresponding to the rate of change in flow rate classified into these two, respectively.
Two types of inspection time (a short inspection time (small time T1) when the flow rate change rate is large, and a long inspection time (large time T2) when the flow rate change rate is small are stored. That is, in this embodiment, the flow rate changes when the gas flow path shutoff means (bidirectional valve) 31 is restored and the gas flow path shutoff means (bidirectional valve) 31 is driven to shut off the gas flow path. The rate is determined and the magnitude is distinguished.Next, the gas flow path shut-off means (bidirectional valve) 3
After 1 is restored again, the flow rate fluctuation value within the inspection time of the length corresponding to the flow rate change rate is obtained. Then, this flow rate fluctuation value is a predetermined value (reference value) (in FIG. 6,
It is judged whether or not it is within Q0). When the flow rate fluctuation value is larger than the reference value, it is judged that there is gas leakage, and when the flow rate fluctuation value is within the reference value, it is judged that there is no gas leakage.

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

According to the detection result of the gas flow rate detecting means 30, the gas flow path is shut off by the gas flow path shutting means (bidirectional valve) 31 and after the restoration work is performed, the gas flow path is shut off by the return shutting means 32. The means 31 is restored (step S7).
00) is the same as the conventional one. In the present embodiment, thereafter, the return flow blocking unit 32 drives the gas flow channel blocking unit 31 to block the gas flow channel (step S701).
In this state, the gas flow rate detecting means 30 detects the flow rate fluctuation in the gas flow path. Then, the determination unit 34 monitors the detection result of the gas flow rate detection unit 30 for a certain period of time (step S702), calculates the flow rate change rate, and discriminates the magnitude of the flow rate change rate (step S70).
3). When the flow rate change rate is large (Y), the gas flow path shutoff means (bidirectional valve) 31 is restored and the gas flow path is opened (step S704). After that, the change state of the flow rate is monitored, and it is determined whether or not the flow rate fluctuation value is within the reference value (Q0) (step S705). If the flow rate fluctuation value is within the reference value (Y) and the predetermined inspection time (small time T1) has elapsed (step S706; Y), the gas leakage is not present (normal) and the return state is maintained (step S70).
7). This completes the gas leak inspection. When the predetermined inspection time (small time T1) has not elapsed (step S7)
06; N), the process returns to step S705. When the flow rate fluctuation value is larger than the reference value (step S705; N)
In the case of gas leakage, the re-cutoff means 35 drives the gas flow path cut-off means (bidirectional valve) 31 again to cut off the gas flow path (step S708).

On the other hand, even when the flow rate change rate is small (step S703; N), the gas flow path blocking means (bidirectional valve) 31
Is restored and the gas flow path is opened (step S70).
9). After that, the change state of the flow rate is monitored, and it is determined whether or not the flow rate fluctuation value is within the reference value (step S71).
0). When the flow rate fluctuation value is within the reference value (Y) and the predetermined inspection time (large time T2) has elapsed (step S7)
In 11; Y), there is no gas leakage (normal) and the return state is maintained (step S707). This completes the gas leak inspection. Predetermined inspection time (large time T2
) If it has not elapsed (step S711; N), the process returns to step S710. Further, when the flow rate fluctuation value is larger than the reference value (step S710; N), it is determined that there is a gas leak, and the re-cutoff means 35 drives the gas flow path cutoff means (bidirectional valve) 31 again, and the gas flow path is opened. It is cut off (step S708).

As described above, in the gas meter 10 of the present embodiment, the gas flow path shut-off means 31 is driven after the gas flow path cut-off means (bidirectional valve) 31 is restored by the return cut-off means 32, and the gas flow path is opened. The flow rate change rate in this state is shut off and measured in real time to determine the magnitude of the flow rate change rate.
Then, after returning the gas flow path shut-off means (bidirectional valve) 31 again, whether the flow rate fluctuation value within the inspection time of a magnitude corresponding to the magnitude of the flow rate change rate is larger than a predetermined reference value. Whether or not there is a gas leak is determined by whether or not there is a gas leak. That is, since the length of the inspection time is changed according to the magnitude of the flow rate change rate, it is possible to accurately perform the gas leakage inspection of a minute flow rate in a short time. This further improves the safety function of the gas meter 10.

Next, a second embodiment of the present invention will be described.

In the first embodiment, the reference value of the flow rate fluctuation is set to be the same (Q0 in FIG. 6) regardless of the magnitude of the flow rate change rate. The size of the reference value of the flow rate fluctuation is changed with the inspection time. That is, when the flow rate change rate is large as shown in the characteristic diagram of FIG.
In the figure, the flow rate fluctuation reference value is small (hereinafter referred to as the first reference value), and when the flow rate change rate is small, as shown in Q2 in the figure, the flow rate fluctuation By setting a large reference value (hereinafter referred to as the second reference value), it is possible to further shorten the inspection time and improve the detection accuracy.

Next, the operation of the gas meter according to the second embodiment will be described with reference to the flow chart of FIG.

In accordance with the detection result of the gas flow rate detection means 30, the gas flow path shutoff means (bidirectional valve) 31 shuts off the gas flow path, and after restoration work is performed, the return shutoff means 32 shuts off the gas flow path. The means 31 is restored (step S9)
00) is the same as the conventional one. In the present embodiment, thereafter, the return flow blocking unit 32 drives the gas flow channel blocking unit 31 to block the gas flow channel again (step S90).
1). In this state, the gas flow rate detecting means 33 detects the flow rate fluctuation in the gas flow path. Then, the determination means 35
The detection result of the gas flow rate detection means 33 is monitored by
The flow rate change rate is calculated, the magnitude of the flow rate change rate is distinguished (step S903), and if the flow rate change rate is large (Y), the gas flow path shut-off means (bidirectional valve) 31 is restored and the gas flow rate is changed. The flow path is opened (step S904). Thereafter, the change state of the flow rate is monitored, and it is determined whether or not the flow rate fluctuation value is within the first reference value (Q1) (step S9).
05). The flow rate fluctuation value is within the first reference value (Y),
When the predetermined inspection time (small time T1) has elapsed (step S906; Y), the gas is not leaked and the recovery state is maintained (step S907). This completes the gas leak inspection. If the predetermined inspection time (small time T1) has not elapsed (step S906; N), step S
Return to 905. Further, when the flow rate fluctuation value is larger than the first reference value (step S905; N), it is determined that there is a gas leak, and the gas flow blocking means (bidirectional valve) 31 is driven again by the re-blocking means 35. The road is blocked (step S908).

On the other hand, when the flow rate change rate is small (step S903; Y), the gas flow path shutoff means (bidirectional valve) 3
1 is restored and the gas flow path is opened (step S90).
9). After that, the change state of the flow rate is monitored, and it is determined whether or not the flow rate fluctuation value is within the second reference value (Q2) (step S910). When the flow rate fluctuation value is within the second reference value (Y) and when the predetermined inspection time (large time T2) has elapsed (step S911; Y), the return state is maintained without gas leakage (step S907). ). This completes the gas leak inspection. Predetermined inspection time (large time T2
) If it has not elapsed (step S911; N), the process returns to step S910. When the flow rate fluctuation value is larger than the second reference value (step S910; N), it is determined that there is a gas leak, and the re-cutting means 35 drives the gas flow path blocking means (bidirectional valve) 31 again to restart the gas flow. The road is blocked (step S908).

According to the present embodiment, not only the inspection time but also the magnitude of the reference value of the flow rate fluctuation is changed according to the magnitude of the flow rate change rate. Therefore, for example, as shown in FIG. The inspection time T1 when the flow rate change rate is large is T1 '
As shown in, the inspection time can be further shortened.

The present invention has been described with reference to the examples.
The present invention is not limited to the above embodiment, but can be variously modified. For example, in the above-described embodiment, the detected flow rate change rate is divided into two sizes, large and small, and the inspection time is set to two large and small according to the magnitude of the flow rate change. The rate may be divided into three or more, and the inspection time may be divided into three or more in accordance with these flow rate change rates, and the reference value of the flow rate variation may be changed correspondingly. You may do it. Further, in the above embodiment, when it is determined that there is a gas leak, the gas flow path is shut off.However, without shutting off the gas flow path, a flashing lamp, a buzzer, or the like indicates that there is a gas leak. You may make it notify.

[0033]

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. After calculating the flow rate change rate in the flow path and then returning the gas flow path shut-off means again, the gas flow rate variation value within the inspection time according to the magnitude of the flow rate change rate exceeds the reference value. Since it is determined whether or not there is a leak, it is possible to perform a gas leak test with a minute flow rate with high accuracy in a short time, and there is an effect that the safety function is further improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a gas meter according to a first 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 a relationship between an elapsed time and a flow rate after the gas cutoff valve of the gas meter of FIG. 1 is returned and the gas flow path is further cut off.

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

FIG. 8 is a characteristic diagram for explaining the operation of the gas meter according to the second embodiment of the present invention.

FIG. 9 is a flow chart for explaining the operation of the gas meter according to the second embodiment of the present invention.

[Explanation of symbols]

10 gas meters 11 housing 13 Gas cutoff valve (bidirectional valve) 14 Gas flow meter 15 Flow rate sensor 16 Control unit 30 Gas flow rate detecting means 31 Gas flow path blocking means 32 Return blocking means 33 storage means 34 Judgment means 35 Re-cutoff means

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-5-26703 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 1/00-9/02

Claims (4)

(57) [Claims] 1. A gas flow rate detecting means for detecting a gas flow rate flowing through a gas flow path, and the gas flow rate detecting means arranged upstream of the gas flow rate detecting means.
According to the detection result of the amount detection means , the gas flow path is blocked and the gas flow path cut-off means is electrically recoverable, and after the gas flow path cut-off means is reset, the gas flow path cut-off means is driven. The gas flow path is blocked by the gas flow path, and after a certain period of time, the gas flow path cut-off means is restored again, and the rate of change of the gas flow rate detectable by the gas flow rate detection means depends on its magnitude. A storage unit that stores the plurality of inspection times in a size inversely proportional to the magnitude of the flow rate change rate, the storage unit being stored separately in a plurality of stages and corresponding to each of the distinguished flow rate change rates; In a state where the gas flow path is shut off after the flow path shutoff means is restored, the detection result of the gas flow rate detection means is monitored and the flow rate change rate is obtained, and the flow rate change rate is stored in the storage means. Which rate of change Whether the flow rate fluctuation value within the inspection time corresponding to the range is within a predetermined reference value after the gas flow path interrupting means is restored again. When the flow rate fluctuation value is larger than the reference value, it is judged that there is a gas leak, and when it is within the reference value, there is a judgment means for judging that there is no gas leak, and when this judgment means judges that there is a gas leak. To
A gas meter, comprising: a re-cutoff unit that drives the gas flow path cutoff unit again to cut off the gas flow path. 2. The gas meter according to claim 1, further comprising, instead of the re-cutoff means, an alarm notifying means for notifying that there is a gas leak by the judging means. 3. A flow rate fluctuation reference value is set to be constant regardless of the magnitude of the flow rate change rate, and the determination means uses the same reference value regardless of the magnitude of the flow rate change rate to determine whether or not there is a gas leak. The gas meter according to claim 1 or 2, wherein the gas meter is judged. 4. The flow rate fluctuation reference value is set in a plurality of stages according to the magnitude of the flow rate change rate, and the judging means uses different reference values according to the magnitude of the flow rate change rate to determine whether or not there is a gas leak. The gas meter according to claim 1 or 2, wherein