JP3445677B2 - Pipe capacity estimation device for 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 pipe capacity estimating device in a gas meter for estimating a downstream pipe capacity.

[0002]

2. Description of the Related Art Generally, the capacity of a gas pipe can be easily measured by knowing the length of a measuring section and the sectional area of the pipe.

By the way, in the case of judging gas leakage from the gas supply pipe, it is conventionally judged from the fluctuation of the gas pressure or the change of the flow rate. It becomes possible to make a more accurate determination of the gas leak according to the above.

[0004]

However, according to the conventional method, the pipe capacity cannot be calculated until the length of the pipe and the diameter of the pipe are measured each time, so that it takes time and trouble to measure. You cannot know the piping capacity in a short time. Therefore, in the gas leak inspection, the current situation is that it is not possible to quickly and more accurately determine the gas leak.

The present invention has been made in view of the above problems, and an object thereof is to easily estimate the capacity of a gas supply pipe on the downstream side of a gas meter in a short time and to perform a more accurate gas leak inspection. It is to provide a pipe capacity estimation device for a gas meter.

[0006]

According to a first aspect of the present invention, there is provided a pipe capacity estimating device for a gas meter, comprising: a gas flow path blocking means capable of blocking and returning the gas flow path; Gas pressure detection means for detecting the gas pressure in the gas flow path on the side, and a time-lapse means for measuring the time transition of the gas pressure detected by the gas pressure detection means when the gas flow path blocking means is restored. And a pipe capacity estimating means for estimating the pipe capacity on the downstream side of the gas flow path blocking means from the time transition of the gas pressure detected by the gas pressure detection means when the gas flow path blocking means is restored. There is.

Specifically, the pipe capacity estimating means is a table in which the relationship between the pressure difference and the time required to reach a predetermined supply pressure after the gas flow path shutting means is restored is represented in advance for each pipe capacity. The pipe capacity is determined by referring to the table from the time difference obtained by the aging means and the pressure difference obtained from the detection result of the gas pressure detection means.

In the pipe capacity estimating device in this gas meter, the pipe capacity on the downstream side of the gas flow path blocking means is estimated from the time transition of the gas pressure detected by the gas pressure detecting means. Therefore, the pipe capacity on the downstream side of the gas flow path blocking means can be easily estimated in a short time, and a more accurate gas leak inspection can be performed.

[0009]

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. Gas cutoff valve 13
Is composed of a valve (bidirectional valve) capable of electrically shutting off and returning.

A pipe 1 is provided between the gas pipe 12 and the gas appliance 18.
7 are linked together. The pipe capacity estimating device of the present embodiment is for estimating the pipe capacity in a portion of the pipe 17 including the downstream portion of the gas cutoff valve 13 of the gas meter 10 at a distance L to the gas appliance 18.

FIG. 2 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
It comprises a (random access memory) 22, a timer 23 and an input / output port 24, which are connected to each other by a bus 25. A gas flow meter 14, a pressure sensor 15, a drive circuit 26 for driving the gas shutoff valve 13, and an alarm lamp 27 for notifying a gas leak are connected to the input / output port 24. In the control unit 16,
CPU 20 uses RAM 22 as a working area for R
By executing the program stored in the OM 21, a function as a gas meter and a pipe capacity estimating function described later are realized.

FIG. 3 shows a functional configuration of the gas meter 10 of this embodiment. That is, this gas meter 10
Is a gas flow path blocking means 30 that can block and restore the gas flow path, and a gas pressure detection means 31 for detecting the gas pressure in the gas flow path downstream of the installation position of the gas flow path blocking means 30. And a time-lapse means 32 for measuring the time transition of the gas pressure detected by the gas pressure detection means 31 when the gas flow path blocking means 30 returns, and a gas pressure detection means when the gas flow path blocking means 30 returns. 31
And a pipe capacity estimating means 33 for estimating the pipe capacity on the downstream side of the gas flow path blocking means 30 from the time transition of the gas pressure detected by.

The gas flow path shutoff means 30 includes a gas shutoff valve (bidirectional valve) 13, a drive circuit 26, and a gas pressure detection means 31.
The pressure sensor 15 and the time measuring means 32 are realized by the timer 23, respectively. The pipe capacity estimating means 33 is realized by the control unit 16.

FIG. 4 shows the relationship between the pressure difference and the time required to reach a predetermined supply pressure after the gas flow path shut-off means 30 (gas shut-off valve 13) has been restored. , Middle, small). As is clear from this figure, the smaller the pipe capacity, the more rapidly the pressure rises and then settles down to the predetermined supply pressure, and the larger the pipe capacity, the smoother the pressure rise up to the supply pressure. Therefore, the piping capacity is estimated from the relationship of piping capacity = f (time, pressure difference) by measuring the time until the gas reaches the predetermined supply pressure after the gas flow path blocking means 30 returns and the pressure difference. be able to. The pipe capacity estimating means 33 of the present embodiment uses this principle, and the relationship between the time until the predetermined supply pressure is reached after the gas flow path shutoff means 30 (gas shutoff valve 13) is restored and the pressure difference. A table that represents in advance for each pipe capacity is prepared in the RAM 32, for example, and is obtained from the detection result of the time (t) obtained by the aging means 32 and the gas pressure detection means 31 (pressure sensor 15) by referring to this table. The pipe capacity is determined from the pressure difference (p).

That is, in the pipe capacity estimating device in the gas meter 10 of the present embodiment, as shown in the flow chart of FIG. 5, after the gas flow path shutoff means 30 (gas shutoff valve 13) is returned (step S500), At the time when a predetermined time (t) has elapsed (step S501; Y), the pipe capacity is estimated from the pressure difference (p) obtained from the detection result of the gas pressure detection means 31 (steps S502, 503). In FIG. 4, it can be estimated that the pipe capacity is large as indicated by the broken line.

As described above, in the pipe capacity estimating device in the gas meter 10 of this embodiment, the pipe capacity is estimated by the transition of the pressure change after the gas flow path shutoff means 30 (gas shutoff valve 13) is returned. Therefore, the pipe capacity can be estimated easily and in a short time.

By the way, there is a certain correlation as shown in FIG. 6 between the estimated pipe capacity and the pressure drop due to gas leakage. That is, both when the pipe capacity is small and when the pipe capacity is large, the gas leak amount increases as the pressure drop amount within a predetermined time increases from the small state. Further, in the case of the same pressure drop amount, the larger the pipe capacity, the larger the gas leak amount.

Therefore, in the inner pipe leakage inspection method in which the gas pressure detection means 31 (pressure sensor 15) is used to judge the gas leakage based on the pressure drop amount, the pipe capacity estimated as described above is taken into consideration as a judgment material. As a result, the amount of gas leakage can be grasped, and the leakage inspection can be performed more accurately.

Next, a specific inspection method by the inner pipe leakage inspection means 33 will be described with reference to FIGS. 7 and 8.

FIG. 7 shows that the gas passage shut-off means 30 (gas shut-off valve 13) is once driven, is restored after the gas passage is shut off, is driven again and is shut off, and the gas passage 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 pressure (P0) hardly changes in the normal time (A), but decreases in the abnormal time (B) with gas leakage with the lapse of time. Gas meter 10 of the present embodiment
Then, at the time when a predetermined time (T1) has elapsed, an appropriate pressure value lower than the normal pressure (P0) is set to the reference pressure (P
It is stored in the RAM 22 as 1) in advance, and it is determined whether or not there is a minute gas leak depending on whether or not the pressure value after re-cutoff has dropped to the reference pressure (P1).

Therefore, when a gas leak occurs and the gas flow path shutoff means (gas cutoff valve 13) 30 is driven to shut off the gas flow path, first, as shown in the flow chart of FIG. It is the same as the conventional one that the gas flow path blocking means 30 is restored after the location is restored (step S601). In this leakage inspection method, the gas flow path shutoff means (gas cutoff valve 13) 30 is driven again after a predetermined time after the recovery to shut off the gas flow path (step S602). Next, in this state, the gas pressure detecting means 31 (pressure sensor 1
The detection result of 5) is monitored for a predetermined time (T1) (step S
603), it is determined whether or not the pressure value has decreased to a preset value (P1) (step S604). When the pressure value has not decreased to the preset value (P1) (N), it is determined to be normal (no gas leakage), and the gas flow path shutoff means (gas shutoff valve 13) 30 is returned to restore the gas flow. The road is opened (step S606). On the other hand, the pressure value has fallen below the preset value (P1) (step S60).
In the case of 4: Y), it is determined that there is an abnormality (there is a gas leak) (step S607), and the fact is notified by blinking a lamp (not shown) or the like (step S608).

The inner pipe leakage inspection can be performed by such a method. In this method, after the gas flow path shut-off means (gas cut-off valve 13) 30 is restored, the gas flow path cut-off means (gas cut-off valve 13) 30 is driven again after a predetermined time has passed to shut off the gas flow path. The pipe capacity estimating device according to the present embodiment automatically estimates the pipe capacity after the gas flow path shutoff means (gas shutoff valve 13) 30 is returned and before a predetermined time elapses. You can Therefore, it becomes easier to more accurately determine the gas leak according to the usage status of the gas appliance by taking into consideration the estimated value of the pipe capacity.

In the above embodiment, the pipe capacity estimating means 33 automatically estimates the pipe capacity, but the estimated value may be displayed on a display unit (not shown).

[0025]

As described above, according to the pipe capacity estimating apparatus for a gas meter of the present invention, the gas flow path shutoff means can be determined from the time transition of the gas pressure detected by the gas pressure detection means after the gas shutoff means is restored. Since the piping capacity on the downstream side of the is estimated, it is possible to easily estimate the piping capacity on the downstream side of the gas flow path blocking means in a short time,
This has the effect of enabling more accurate gas leak inspection.

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

FIG. 3 is a functional block diagram for explaining a pipe capacity estimation function in the gas meter of FIG.

FIG. 4 is a characteristic diagram showing a transition state of pressure change after return of the shutoff valve in the gas meter of FIG.

5 is a flow chart for explaining a pipe capacity estimating operation by the gas meter of FIG. 1. FIG.

FIG. 6 is a diagram for explaining a correlation between a pipe capacity, a pressure drop amount after returning from a shutoff valve, and a gas leak amount.

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

8 is a flow chart for explaining an inner pipe leakage inspection operation of the gas meter of FIG.

[Explanation of symbols]

10 gas meters 13 Gas cutoff valve (bidirectional valve) 14 Gas flow meter 15 Pressure sensor 16 Control unit 30 gas flow path cutoff means (gas cutoff valve 13) 31 gas pressure detection means (pressure sensor 15) 32 Time Means (Timer 23) 33 Pipe capacity estimating means

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-7-24660 (JP, A) JP-A-7-27591 (JP, A) JP-A-63-139227 (JP, A) Actual development Sho-62- 126743 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F17D 1/00-5/08 G01M 3/28 F16L 55/00

Claims (2)

(57) [Claims] 1. A gas flow path blocking means capable of blocking and restoring the gas flow path, and a gas pressure detecting means for detecting a gas pressure in a gas flow path downstream of an installation position of the gas flow path blocking means. A time-lapse means for measuring the time transition of the gas pressure detected by the gas pressure detection means when the gas flow path cutoff means returns, and the gas pressure detection means when the gas flow path cutoff means returns. And a pipe capacity estimating means for estimating the pipe capacity on the downstream side of the gas flow path blocking means from the time transition of the gas pressure detected by the pipe capacity estimating device in the gas meter. 2. The pipe capacity estimating means has a table in which the relationship between the pressure difference and the time until the supply pressure reaches a predetermined value after the gas flow path shutting means is restored is shown in advance for each pipe capacity. 2. The pipe capacity estimating device for a gas meter according to claim 1, wherein the pipe capacity is determined by referring to the table based on a time difference obtained by the aging means and a pressure difference obtained from a detection result of the gas pressure detecting means. .