JP3339385B2 - Gas meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a gas meter,
In particular, the present invention relates to a gas meter having a shutoff valve for preventing a gas leak accident or the like.

[0002]

2. Description of the Related Art In a conventional gas meter, if a gas leak occurs in a gas appliance or the like, there is a danger of an accident. Therefore, a detector for detecting such a gas leak and stopping the gas flow. And a shutoff valve is used.

[0003] Such a shut-off valve 11 (herein referred to as a shut-off valve including not only the valve itself but also an electromagnetic power for moving the same. The same applies hereinafter), for example, as shown in FIG.
It is located at the upstream pipe inlet of the gas meter. In FIG. 3, reference numeral 12 denotes an airtight chamber of the membrane gas meter, and reference numeral 13 converts the movement of the mechanism of the membrane flowmeter operating inside the airtight chamber 12 into a rotating action, and the number of rotations thereof is increased. Gas flow rate detecting means for detecting a pulse corresponding to the gas flow rate;
A CPU having built therein gas flow integrating means for calculating a gas flow rate based on the pulse detected in step 3 and further integrating the gas flow rate and abnormality detecting means for detecting the occurrence of an abnormality in the gas flow; Reference numeral 15 denotes an I / O between the CPU 14 and peripheral devices such as the gas flow rate detecting means 13 outside the CPU 14.
An I / F means 16 for controlling an F (interface) is a display means such as a liquid crystal display panel for displaying information such as the integrated gas flow rate calculated by the CPU 14.

When an abnormal condition of the gas flow is detected by the CPU 14 in which the abnormality detecting means is constructed as described above, the shut-off valve 1 is controlled based on the detected condition and the valve body is closed, so that the valve is moved downstream from the gas meter. Stop the gas flow.
In this way, even if a gas leak occurs, the safety can be ensured by detecting the gas leak and shutting off the gas flow by the shutoff valve 1. Then, after exiting from the abnormal state, the shut-off valve 11 is returned to the open state by inputting a valve return command to the CPU 14 by, for example, operating the return switch 17 by the user of the gas.

[0005] However, such a conventional shut-off valve 1
In the gas meter using the fuel cell 1, the shut-off valve is deliberately generated by inputting a command input such as the occurrence of the above-mentioned abnormal condition or the so-called test shut-off for operating the shut-off valve 1 in a test manner. Except for shutting off the valve 11, the shut-off valve 11 rarely opens and closes under normal gas use conditions, and the shut-off valve 11 remains open for a long period of time, possibly for several years. Become. As a result, due to the long-term adhesion of oily sludge, dust, moisture, and the like contained in the gas, rubbing portions of mechanical parts such as the valve body of the shut-off valve 11 and the like, There has been a problem that the shut-off valve 1 does not operate normally due to sticking or rusting of each part such as a contact portion, and it may even be impossible to ensure safety at the time of gas leakage or the like.

Therefore, in order to solve such a problem,
For example, a technique disclosed in Japanese Patent Application Laid-Open No. 8-28779 according to the present applicant has been devised. This means that the timer operates at a predetermined time, such as 100 hours, which is set in advance. If the gas is not used at that time and the gas is stopped, the shutoff valve 11 is once closed and then reopened. The automatic operation is performed to prevent the sliding portion and the contact portion such as the valve body of the shut-off valve 11 from sticking or rusting.

[0007] The so-called test shut-off operation of such an automatic shut-off valve is programmed by executing the above-mentioned timer or the like so as to be executed particularly at night when the frequency or probability of using gas is low. The test shut-off operation of the shut-off valve is automatically performed effectively without adversely affecting the use of ordinary gas.

[0008]

However, in the conventional gas meter as described above, the movable body such as the valve body of the shut-off valve 11 and an electromagnet as the power for moving the shut-off valve is fixed or rusted, so that the shut-off valve is damaged. If a malfunction occurs in the sense that the 11 is not completely closed (that is, the gas cannot be completely shut off and leaks little by little), it is caused by such a small incomplete shutoff. Then, even if gas flows little by little from the imperfect shut-off part of the shut-off valve, it is overlooked without being detected by a gas leak sensor etc. due to the small amount, and the shut-off valve operates normally. As a result, there is a problem that a malfunction of the shut-off valve cannot be accurately detected.

On the other hand, as means for detecting the occurrence of an abnormality in the shut-off operation of a shut-off valve in a conventional gas meter, generally, an integrated flow value of gas flowing while the shut-off valve is in a closed (cut-off) state is determined in advance. When a certain value or more is detected, a means for detecting that an abnormality has occurred in the closing operation of the shut-off valve is used. However, in determining the occurrence of the abnormality, a time term (time condition or information or the like) is used. ) Is not included, so when a small amount of gas flows from the incomplete shutoff portion of the shutoff valve as described above, the flow value is integrated over a long period of time to reach the predetermined constant value. It reaches and is detected as occurrence of an abnormality. In this way, even when the shut-off valve is incompletely interrupted to such an extent that there is practically no obstruction, a small amount of gas flow due to this is accumulated, and as a result, it is determined that an abnormality has occurred. In some cases.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem in detecting an abnormality in the operation of a shut-off valve. The main problem is to automatically and accurately generate a malfunction of the shut-off valve with a high probability. The malfunction of the shut-off valve can be more reliably eliminated by classifying the degree of malfunction of the shut-off operation into a plurality of stages and taking appropriate measures according to the degree of the malfunction. It is therefore an object of the present invention to provide a gas meter which can reliably operate a shut-off valve which needs to be actually shut off when an abnormality occurs, thereby ensuring safety as a usage environment of the gas meter.

[0011]

The gas meter according to the present invention comprises:
First, a gas flow rate measuring means 1 for measuring a gas flow rate,
Gas flow rate integrating means 2 for integrating the measured gas flow rates
And an instantaneous flow rate detecting means 4 for detecting an instantaneous flow rate value Q1 of the gas immediately after the operation of the shutoff valve 3 in a gas meter having a shutoff valve 3 for shutting off the gas flow;
An instantaneous flow rate comparing means 5 for comparing an instantaneous flow rate value Q1 of the gas detected by the instantaneous flow rate detecting means 4 with predetermined thresholds A and B; The first shut-off operation is performed by controlling the shut-off valve 3, and after the instantaneous flow rate detection means 4 detects the instantaneous flow rate value Q 2 of the gas after the execution of the first shut-off operation, the instantaneous flow rate detection means 4 further performs the following shut-off operation. After opening the shutoff valve 3 once, the second
A shut-off valve control means 6 for continuously executing a series of operations of performing the shut-off operation once or more times at each time,
Instantaneous flow value Q of the gas after execution of the first shut-off operation
1 and the instantaneous flow value Q2 of the gas after the execution of the second shut-off operation is compared with a first threshold value A. When it becomes equal to or greater than the threshold value A, it is determined that the shut-off abnormality has occurred in the shut-off valve 3, while the instantaneous flow value Q1 of the gas after the execution of the first shut-off operation and the second The instantaneous flow value Q2 of the gas after the execution of the shutoff operation is set to a second threshold value B set to a value lower than the first threshold value A.
If the instantaneous flow values Q1 and Q2 are both continuously smaller than the second threshold value B, the shut-off abnormality is determined to be that the shut-off valve 3 has normally operated. It is characterized by comprising a judging means 7 and an alarm generating means 8 for alarming the occurrence of the shut-off abnormality when it is judged that the shut-off abnormality has occurred in the shut-off valve 3.

That is, in so-called test shut-off, not only one shut-off operation is performed, but also the opening / closing operation of the valve body of the shut-off valve is repeatedly performed two or more times, and mechanical operation by the open-close operation is performed. The effect and the pulsating pressure change and flow rate change of the gas accompanying the opening and closing operation cause high opening and closing operation of the shut-off valve. Viscous resistance due to deposits, or mechanical resistance such as frictional force or fusing force due to rust between metal materials of the valve element and nozzle or rust inside the valve element drive device, etc. It is possible to drop off, and the original complete shutoff operation (opening / closing operation) as the shutoff valve can be restored. In addition, at this time, not only the valve body opening / closing operation is repeated mechanically, but also the opening / closing operation is repeated many times. The instantaneous flow values Q1 and Q2 of the gas are detected based on the value of the measured value itself and the degree of the change, compared with the case where the instantaneous flow value is detected only once after the conventional one-time shutoff operation.
Further, it is possible to more accurately determine the occurrence of an abnormality in consideration of the degree of the interruption abnormality.

That is, after the first shut-off operation, the instantaneous flow value Q1 of the gas, that is, the flow rate of gas leakage from the shut-off valve at that time is detected, and this is set to a first threshold value set to a considerably higher value. If the value is higher than the first threshold value A as compared with A, then it means that a considerably large interruption abnormality has occurred at that time. Further, following this, after performing the second shut-off operation, that is, the opening / closing operation for lowering the resistance at the time of opening / closing caused by the deposits and rust, etc., the instantaneous gas flow rate value Q2 is detected again. This is compared with the first threshold value A, and if the instantaneous flow rate value Q2, that is, the flow rate of gas leakage is a value higher than the first threshold value A, the cutoff abnormality at that time is one time. Since the opening / closing operation for lowering the resistance has hardly been improved, it is appropriate to determine that the interruption abnormality is quite serious. Or, in other words, it is possible to accurately and accurately determine that the interruption abnormality has occurred with a considerably high probability.

On the other hand, the instantaneous flow value Q1 of the gas detected after the first shut-off operation is changed to the first threshold A
Is compared with a second threshold value B having a lower value. If the instantaneous flow rate value Q1 is higher than the second threshold value B at this time, the degree of the shutoff abnormality is lower in that case than in the case of the first threshold value A abnormality (or Although the probability of being able to make a determination is low) or moderate or lower, it is possible to determine with adequacy that a blocking abnormality may have occurred. Therefore, following this, a second shutoff operation (opening / closing operation of the valve body) is performed in order to reduce the resistance of the high viscous deposits or the like in the valve body, which is a main cause of the occurrence of the shutoff abnormality. And the instantaneous gas flow value Q2
Is again compared with the second threshold value B. As a result, if the instantaneous flow rate value Q2 is now less than the second threshold value B, the effect of the second shut-off operation is exerted, and a normally-sufficient normal shut-off is executed. Can be determined. However, if the instantaneous flow rate value Q2 still remains at or above the second threshold value B, the effect of the second shut-off operation is not sufficient, and the middle-level or lower shut-off failure still continues. Will be.
Therefore, in that case, it is possible to accurately and accurately determine that the interruption is abnormal.

In this manner, the gas meter according to the present invention automatically and reliably detects the occurrence of a malfunction of the shut-off valve,
In addition, the degree of malfunction of the shut-off valve at that time is divided into a plurality of stages, and a measure corresponding to the degree of the malfunction is appropriately taken, whereby the malfunction of the shut-off valve can be eliminated. In addition, the above-mentioned flow rate detection does not require measurement over a long period of time as in the prior art, and can be measured almost instantaneously by the instantaneous flow rate detection means 4. It is possible to prevent the error of the interruption abnormality determination and the loss of reliability.

As a result of realizing such a function, it is possible to reliably operate a shut-off valve which needs to be actually shut off when an abnormality occurs, and to secure safety as a usage environment of the gas meter. The second threshold value B is set to 0.25 l / h as a flow rate which is generally considered to be 0 in a gas meter, and this value is actually used in practice. Because
It is preferable to set this 0.25 l / h as the second threshold value B. Alternatively, a value which is still lower than 0.25 l / h and which is not less than the measurement limit value of the gas flow rate measuring means 1 (that is, a lower limit value which is a value higher than the minimum value of the measurement error). May be set. By setting B to such a low value, it is possible to more strictly check for an interruption abnormality. Also, the first threshold A
Also, if the value A is set to a higher value, the check for interruption abnormality is determined in a less strict direction. Conversely, if the value A is set to a lower value, the check for interruption abnormality is determined in a stricter direction. Therefore, in consideration of the above-described directionality, the value of the first threshold value A or the value of the second threshold value B may be appropriately set in accordance with the strictness required for the interruption operation check. .

Secondly, the gas meter of the present invention has a gas flow rate measuring means 1 for measuring a gas flow rate, a gas flow rate integrating means 2 for integrating the measured gas flow rate, and shuts off the gas flow. In the gas meter having the shutoff valve 3, an instantaneous flow rate detection means 4 for detecting an instantaneous flow rate value Q1 of the gas immediately after the operation of the shutoff valve 3, and an instantaneous flow rate of the gas detected by the instantaneous flow rate detection means 4 An instantaneous flow rate comparing means 5 for comparing the value Q1 with one of predetermined first and second threshold values A and B at a time, and an alarm generating means 8 for alarming that a shut-down abnormality has occurred. Shut-off valve control means 6 for controlling the opening and closing operation of the shut-off valve 3 including at least a first shut-off operation for controlling the shut-off valve 3 to execute the shut-off at every time interval of a predetermined time interval ΔT.
And an instantaneous flow value Q of the gas immediately after the first shut-off operation.
If 1 is equal to or greater than a predetermined first threshold value A, the shut-off valve control means 6 once opens the shut-off valve 3 and then performs a second shut-off operation. If the instantaneous flow value Q2 of the gas is equal to or greater than the first threshold value A even after the shutoff operation is performed, the shutoff valve 3
It is determined that a shut-down abnormality has occurred, and an alarm is generated by the alarm generating means 8, and after the execution of the second shut-off operation, the instantaneous flow value Q2 of the gas is reduced to the first threshold A.
If the value is not less than the second threshold value B and less than the first threshold value A, the shut-off valve control means 6 further opens the shut-off valve 3 once, 3. If the instantaneous flow value Q3 of the gas is greater than or equal to the second threshold value B after the execution of the third shutoff operation, the shutoff operation of the shutoff valve 3 has occurred. When the instantaneous flow value Q3 of the gas is less than the second threshold value B after the execution of the third shutoff operation, the normal shutoff is performed. If the instantaneous flow value Q1 of the gas immediately after the first shutoff is less than the first threshold value A or more than the second threshold value B, After the shutoff valve 3 is once opened by the shutoff valve control means 6, the second A shut-off operation, and if the instantaneous flow value Q2 of the gas is equal to or higher than the second threshold value B even after the execution of the second shut-off operation, a shut-off abnormality has occurred in the shut-off valve 3. And an alarm is generated by the alarm generating means 8. If the instantaneous gas flow rate value Q2 is smaller than the second threshold value B after the execution of the second shutoff operation, the normal shutoff is performed. Has been executed, and when the instantaneous flow value Q1 of the gas immediately after the first shutoff is less than the second threshold value B, it is determined that the normal shutoff has been executed. This is a gas meter including a shut-off abnormality determining means 7.

That is, if the technology of the gas meter according to the first aspect of the present invention described above is a form that is closer to the embodiment and is the most preferred form, the form described in the second aspect is most preferable. It can be said that it is one form.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a gas meter according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing an outline of the structure of a gas meter according to the present invention. FIG. 2 is a schematic flowchart showing a main operation centering on the test interruption operation.

This gas meter, such as a membrane type capacity meter or a turbine type flow meter, generates an electric pulse corresponding to the flow amount of the gas 100 and outputs this as measurement data of the gas flow rate Q. Among the meters, a gas meter main body 101 having a built-in gas flow measuring means 1 using an ultrasonic flow meter, which is a typical one of a so-called inferential type, and the gas in the gas meter main body 101 A gas flow integrating means for integrating the gas flow based on a pulse or the like corresponding to the flow amount of the gas measured by the flow measuring means (hereinafter referred to as a flow rate); A structure having a shut-off valve 3 and a function of integrating a gas flow rate thereby;
When an abnormality occurs in the gas pressure, the gas flow rate, or the like detected by a pressure sensor (not shown) in the gas meter, the shut-off valve control unit 6 having a function according to the present invention as described later has The structure and the function of the shut-off valve that shuts off the gas flow under the control are the same as those of the gas meter described in the above description of the related art. The technology according to the present invention is applied to such a gas meter.

That is, this gas meter further comprises an instantaneous flow rate detecting means 4 for detecting an instantaneous flow rate value Q1 of the gas immediately after the shut-off valve 3 operates, and an instantaneous flow rate of the gas detected by the instantaneous flow rate detecting means 4. An instantaneous flow rate comparing means 5 for comparing the flow rate value Q1 with at least one of predetermined first and second threshold values A and B at a time, and shutting off each time at a predetermined time interval ΔT Shut-off valve control means 6 for controlling the opening and closing operation of the shut-off valve 3 including at least a first shut-off operation for controlling the valve 3 to execute shut-off, and shut-off abnormality judgment for judging whether or not normal shut-off has been executed The gas meter is provided with a means 7 and an alarm generation means 8 for issuing an alarm when the interruption abnormality occurs in the interruption abnormality determination means 7.

Here, the interruption abnormality judging means 7 will be described in detail. The operation described below is performed in the interruption abnormality determination means 7. That is, if the use of the gas is stopped (not shown here) at every time interval of a certain time interval ΔT, the first shutoff operation is executed (s1).

When the instantaneous flow value Q1 of the gas immediately after the first shutoff operation is equal to or more than the first threshold value A (Y in s2), the shutoff valve control means 6 shuts off the gas. After the valve 3 is once opened, the second shutoff operation is performed (s
3) When the instantaneous gas flow value Q2 is equal to or larger than the first threshold value A even after the execution of the second shutoff operation (s4).
(Y), it is determined that the shut-off abnormality has occurred in the shut-off valve 3 (s5), and an alarm is generated by the alarm generating means 8 (s6). Further, this alarm may be transmitted to an external information central management system or the like via a communication means (not shown). In this way, the abnormal cutoff is alarmed, and after the abnormality is confirmed by the user or the gas company, a reset command is input through, for example, a reset switch (not shown), and the alarm reset is executed (s7). The state returns to s1.

On the other hand, here, after the execution of the second shut-off operation, the instantaneous flow rate value Q2 of the gas is smaller than the first threshold value A and set to a value lower than the first threshold value A. If the threshold value is equal to or higher than B (Y in s8), the shutoff valve 3 is once opened by the shutoff valve
Is performed (s9). However, if the instantaneous flow rate value Q2 is less than the second threshold value B (N in s8), it is determined that normal shutoff has been performed (s11).

Subsequently, after the execution of the third shut-off operation (s9), if the instantaneous gas flow value Q3 is equal to or more than the second threshold B (Y of s10), the shut-off valve 3 It is determined that a shut-down abnormality has occurred (s5), and an alarm is generated by the alarm generating means 8 (s6). Alternatively, if the instantaneous gas flow value Q3 is less than the second threshold value B after the execution of the third shut-off operation (s9), (s1
0, N), it is determined that the normal shutoff has been performed (s
11).

On the other hand, when the instantaneous flow value Q1 of the gas immediately after the first shut-off is less than the first threshold value A (N of s2) and greater than or equal to the second threshold value B Has (s
12) The second shut-off operation is performed after the shut-off valve 3 is once opened by the shut-off valve control means 6 (s13). After the second shut-off operation is performed, the instantaneous gas flow rate value Q2 is changed to the second shut-off operation. If the value is equal to or greater than the threshold value B (Y in s14), it is determined that a shutoff abnormality has occurred in the shutoff valve 3 (s14).
5) An alarm is generated by the alarm generating means 8 (s6). However, if the instantaneous gas flow value Q2 is smaller than the second threshold value B after the execution of the second shutoff operation (s13) (N of s14), the normal shutoff is executed. Is determined (s11).

On the other hand, if the instantaneous flow value Q1 of the gas immediately after the first cut-off (s1) is less than the second threshold value B (N of s2 and N of s12), at this time, It is determined that the normal shutoff has been executed (s11). When it is determined that the normal shutoff has been performed, the state returns to the normal gas use state again (that is, to s1).

As described above, the cut-off abnormality judging means 7 executes the main operation when the test is cut off. This makes it possible to automatically and reliably detect the occurrence of a malfunction of the shut-off valve with a high degree of validity. By taking measures corresponding to the above, the malfunction of the shut-off valve can be eliminated more reliably, and the shut-off valve, which needs to be actually shut off when an abnormality occurs, can be reliably operated, and the safety of the gas meter operating environment can be improved. Nature can be secured.

The gas flow integrating means 2, the instantaneous flow rate detecting means 4, the instantaneous flow rate comparing means 5, the shut-off valve control means 6, and the shut-off abnormality judging means 7 have the I / F as shown in FIG. A so-called one-chip microcomputer (microcomputer) connected to the shut-off valve 3 and the measuring means of the gas meter main body 101 via the (interface) 102 may be constructed inside the CPU 103. Alternatively, it goes without saying that each of these means may be constructed by a combination of individual (discrete) circuits or circuit elements. However, as for the structure of the circuit system and the hardware resources such as the one-chip microcomputer used for the same, considering the manufacturing and cost advantages that almost the same as the conventional one can be applied effectively, It is preferable to construct the main part of the configuration of the present invention inside a one-chip microcomputer.
Therefore, in this embodiment, a circuit structure using such a one-chip microcomputer is adopted.

In the present embodiment, a gas flow meter is used as the gas flow rate measuring means 1, and the gas flow rate value used for calculating the integrated data of the normal gas consumption is also changed to the instantaneous flow rate detecting means according to the present invention. 4, the gas flow value (data) measured from the gas flow rate measuring means 1 is used. However, the gas flow rate measuring means 1 may be, for example, a film type gas. When the flow rate measuring means is used, this membrane type is generally unfamiliar with the measurement of the instantaneous flow rate, and therefore, for example, an ultrasonic wave suitable as a measuring means for measuring the instantaneous flow rate value used in the instantaneous flow rate detecting means 4 and the like The gas flow measuring means of the system must be arranged separately from the gas flow measuring means of the film type. Therefore, it is needless to say that the functions and effects similar to the functions and effects shown in the above-described embodiment by the technology according to the present invention can be obtained, although the structure is complicated due to such a slight addition.

The alarm generating means 8 may be a means for notifying an alarm by sounding a buzzer, for example, when the above-mentioned shut-down abnormality has occurred, or visualizing information on the occurrence of the shut-off abnormality separately or simultaneously with the alarm. The information may be displayed and notified. However, in any case, it is needless to say that it is desirable that the alarm is easily recognized by the user.

[0032]

As described above, according to the present invention, the occurrence of a malfunction of the shut-off valve can be accurately and automatically detected with a high probability. By classifying the degree of failure into a plurality of stages and taking appropriate measures according to the degree of operation failure, the operation failure of the shut-off valve can be more reliably eliminated, and the shutdown that actually needs to be shut off when an abnormality occurs It is possible to provide a gas meter that enables a reliable operation of a valve and ensures safety as a usage environment of the gas meter.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a main part of a configuration of a gas meter according to the present invention.

FIG. 2 is a flowchart showing an outline of a main operation of the gas meter according to the present invention.

FIG. 3 is a diagram showing an outline of a main part of a configuration of a conventional gas meter having a shutoff valve and the like.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Gas flow rate measuring means 2 ... Gas flow rate integrating means 3 ... Shut-off valve 4 ... Instantaneous flow rate detecting means 5 ... Instantaneous flow rate comparing means 6 ... Shut-off valve control means 7 ... Shut-off abnormality determination means 8 ... Alarm generation means 100 ... Gas 101 ... Gas meter body 102: I / F 103: CPU

Claims (2)

(57) [Claims] 1. A gas meter comprising: gas flow rate measuring means for measuring a gas flow rate; gas flow rate integrating means for integrating the measured gas flow rate; and a shutoff valve for shutting off the flow of the gas. An instantaneous flow rate detecting means for detecting an instantaneous flow rate value of the gas immediately after the operation, and an instantaneous flow rate comparing means for comparing the instantaneous flow rate value of the gas detected by the instantaneous flow rate detecting means with a predetermined threshold value. Controlling the shutoff valve at each time interval with a constant time interval, performing a first shutoff operation, and detecting the instantaneous flow value of the gas after the execution of the first shutoff operation by the instantaneous flow detection means. A series of operations of performing the second shutoff operation after once opening the shutoff valve following the shutoff operation after the
A shutoff valve control means that is executed once or more times continuously for each time; an instantaneous flow value of the gas after the execution of the first shutoff operation and a flow rate of the gas after the execution of the second shutoff operation; The instantaneous flow rate value is compared with a first threshold value, and when both of the instantaneous flow rate values are continuously equal to or greater than the first threshold value, a shut-off abnormality has occurred in the shut-off valve. On the other hand, the instantaneous flow value of the gas after the execution of the first shutoff operation and the instantaneous flow value of the gas after the execution of the second shutoff operation are set to be smaller than the first threshold value. When the two instantaneous flow values are continuously less than the second threshold value as compared with the second threshold value set to a low value, the shut-off valve normally operates. Shutoff abnormality determining means for determining that a shutoff abnormality has occurred in the shutoff valve; If the the gas meter is characterized in that a warning generating means for warning the occurrence of the blocking abnormal. 2. A gas meter comprising: a gas flow rate measuring means for measuring a gas flow rate; a gas flow rate integrating means for integrating the measured gas flow rate; and a shutoff valve for shutting off the gas flow. An instantaneous flow rate detecting means for detecting an instantaneous flow rate value of the gas immediately after the operation of the gas, and an instantaneous flow rate value of the gas detected by the instantaneous flow rate detecting means, the first and second threshold values being predetermined. An instantaneous flow rate comparing means for comparing with at least one of them at a time, an alarm generating means for alarming that a shut-off abnormality has occurred, and a first shut-off for executing the shut-off by controlling the shut-off valve at regular intervals. Shut-off valve control means for opening and closing the shut-off valve including at least an operation, when an instantaneous flow value of the gas immediately after the first shut-off operation is equal to or more than a predetermined first threshold value; A second shutoff operation is performed after the shutoff valve is once opened by the shutoff valve control means, and the instantaneous flow value of the gas is not less than the first threshold value even after the execution of the second shutoff operation. If there is, it is determined that a shut-down abnormality has occurred in the shut-off valve, and an alarm is generated by the alarm generating means. After the execution of the second shut-off operation, the instantaneous flow value of the gas is reduced to the first flow rate. When the value is equal to or more than the second threshold value and less than the first threshold value, which is set to a value less than the threshold value,
The third shut-off operation is performed after the shut-off valve is once opened by the shut-off valve control means, and the instantaneous flow value of the gas is equal to or more than the second threshold after the third shut-off operation is performed. In this case, it is determined that the shut-off abnormality has occurred in the shut-off valve, and an alarm is generated by the alarm generating means. After the execution of the third shut-off operation, the instantaneous flow value of the gas becomes equal to the second threshold value. If it is less than the threshold value, it is determined that the normal shutoff has been performed, while the instantaneous flow value of the gas immediately after the first shutoff is less than the first threshold value or the second threshold value. In the case described above, a second shut-off operation is performed after the shut-off valve is once opened by the shut-off valve control means, and the instantaneous flow value of the gas is maintained at the second flow even after the execution of the second shut-off operation. If the threshold value is 2 or more, When it is determined that a shutoff abnormality has occurred in the valve, an alarm is generated by the alarm generating means, and the instantaneous flow value of the gas is less than the second threshold value after the execution of the second shutoff operation. It is determined that a normal shutoff has been performed, and if the instantaneous flow value of the gas immediately after the first shutoff is less than the second threshold, the normal shutoff has been performed. A gas meter, comprising: a shut-off abnormality determining means for determining whether the gas flow is abnormal.