JPH11108730A - Gas meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To immediately detect a gas leakage in an upstream side by a gas meter by providing an inverse-flow detecting means for detecting the inverse- flowing of gas from its forward flow. SOLUTION: In order to deal with the inverse-flowing of gas 100 from forward flowing from an upstream side pipe 101 to a downstream side pipe 102, a gas fluid data measuring means 103 is provided with a function of measuring the fluid physical amount of this inverse-flow, and a gas flow rate calculating means 104 is also provided with a function of detecting the same based on the measured data of the inverse-flow. When a fissure 200 occurs in the upstream side pipe 101 of a gas meter 300 and a gas leakage 201 occurs in this part, an inverse-flow is generated at least between the inside of the gas meter 300 to the upstream side pipe 101. Thus, the gas flow rate calculating means 104 detects the generation of the inverse-flow based on the inverse-flow measured data of the gas fluid data measuring means 103, and also detects the gas leakage 201 in the upstream side pipe 101. Then, an alarm is issued from an alarming means 105.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a gas meter.

[0002]

2. Description of the Related Art Generally, a gas meter has a function of accurately detecting and warning a gas leak or an abnormality of a gas flow rate, and various functions for stopping supply of gas. Generally, in such a conventional gas meter, for a gas leak downstream of the gas meter, that is, a portion near a gas appliance that consumes gas, for example, a gas leak detection device called a flow rate minute leak warning device is built in the gas meter. This enables detection.

[0003] In such a flow rate type micro-leakage warning device for detecting gas leakage on the downstream side, a very small gas flow continues for more than 30 days downstream of a gas meter incorporating the device. In this case, a warning is issued or the gas flow is stopped on the assumption that a minute leak of gas has occurred on the downstream side of the gas meter.

[0004] However, if a gas leak occurs due to breakage of a gas pipe, for example, on the upstream side instead of the downstream side of the gas meter, the above-mentioned flow rate type minute leak warning is given for the gas leak on the upstream side. It is practically impossible for the device to detect it. This is because gas meters are generally designed to measure the flow of gas flowing in the forward direction from the upstream side to the downstream side of the gas, and the above-mentioned flow type micro-leakage warning device is used to measure the gas flowing in the forward direction. 3
By monitoring over 0 days, a gas leak on the downstream side of the gas meter can be detected. If a gas leak occurs on the upstream side, the gas flow on the gas meter itself and the gas flow on the downstream side thereof can be detected. Rather, it becomes impossible to discriminate between this state and the normal gas flow stop state, so that the above-mentioned flow-type minute leakage warning device cannot detect gas leakage on the upstream side.

[0005] Conventional gas flow abnormality detecting means includes a gas meter, and a gas pipe through which the gas pressure change at the time of stopping gas use is less than a certain value. A pressure-type micro-leakage device that determines that an abnormality has occurred somewhere is used.

Alternatively, instead of being built in the gas meter main body, it is arranged immediately upstream of the regulator outlet on the upstream side of the gas meter or between the regulator outlet side and the gas meter to detect pressure fluctuations upstream of the gas meter. A pressure sensor installed separately from the gas meter and a shutoff valve controlled by receiving the pressure sensor are used.

However, in the above-mentioned pressure type micro-leakage device, etc., since the gas leak or the like is detected by monitoring the pressure of the gas in the entire gas pipe as a parameter, the gas leak in the entire gas pipe is detected. It is impossible to specify in which location the gas pipe is damaged or gas leaks occur. In other words, it is possible to detect that a gas leak has occurred somewhere, but it is practically difficult to specify whether it is upstream or downstream. There is a problem that it is impossible to take measures to stop the flow. Further, as long as the pressure value is not abnormal continuously for more than 30 days, for example, when the gas pipe on the upstream side is damaged and a large amount of gas leaks, this pressure type micro leak device can be used. However, there is a problem that an alarm or a stop operation cannot be performed instantaneously in the case of the damage.

[0008] In particular, the gas pipe upstream of the gas meter is generally arranged outside the house or building, and the gas user is generally located inside the house or building. If the gas leaks and the gas leaks, it is not always possible to immediately confirm the gas leak, and there is a risk that the gas leak may be overlooked.
In addition, gas leak alarms, which are separate from conventional gas meters, are generally installed for indoor use. If an external gas pipe or the like is damaged, it cannot be immediately alarmed. It is. Even if such a gas leak alarm is arranged outside a room, the gas leaked outside is generally immediately diffused to the outside air. Is not detectable.

[0009] Further, the pressure sensor, which is arranged separately from the gas meter and upstream of the gas meter, also requires complicated equipment and piping due to the addition of the device itself, and also has a troublesome work of mounting the same. There is a problem that there is. In addition, gas leak detecting means for detecting abnormal pressure of the regulator, detecting abnormal closing pressure when the use of gas equipment is stopped, or determining the pressure in the gas pipe during gas use When the pressure drops below the value, some are judged to be abnormal, but all of them use the detected gas pressure as a parameter to detect abnormal adjustment pressure, blockage pressure, or pressure drop when using gas, respectively. Even if these are also used for detecting gas leaks in the upstream piping, if an abnormal value occurs in one of the parameters of the gas pressure, is the cause corresponding to the abnormal pressure abnormality or the like the original one? Or two or more events, such as gas leaks in the upstream piping, etc., cannot be specified. There is a problem that is.

As a device for detecting a gas leak on the upstream side of the gas meter, there is a simple upstream leak detection device, which also supplies an automatic switching regulator with a transmission function which is arranged separately from the gas meter. The timing at which the start signal is issued is compared with the integrated value of the gas meter.If it is determined that the replenishment start signal is issued much earlier than the integrated value of the gas meter, it is determined that an abnormality has occurred on the upstream side. However, if such a device is attached separately from the gas meter, there is a problem that the overall configuration including the gas meter and its piping becomes complicated.

[0011]

As described above, various gas leak detecting means incorporated in a conventional gas meter, various conventional gas leak alarms which are disposed separately from the gas meter, and the like. In particular, it is difficult to detect a gas leak caused by a breakage in an upstream pipe closer to a gas supply source than a gas meter, and when such a gas leak occurs, it is immediately detected and warned. There was a problem that was impossible. In addition, when an upstream pressure sensor disposed separately from the gas meter is used, there is a problem that the addition of the device complicates the overall structure, piping, mounting, and the like.

The present invention has been made to solve such a problem, and particularly means for immediately detecting a gas leak caused by breakage of a gas pipe on the upstream side of a gas meter, and further provides a warning thereof. It is an object of the present invention to realize a gas meter having a means for emitting light.

[0013]

First, a gas meter according to the present invention is installed between an upstream pipe near a gas supply source and a downstream pipe near a gas appliance consuming the gas, In a gas meter having gas flow rate measuring means for measuring a flow rate of the gas flowing in a forward direction from a side pipe to the downstream side pipe, a backflow detecting the backflow when the gas flows backward in a direction opposite to the forward direction It is characterized by having a detecting means.

That is, when the gas pipe on the upstream side of the gas meter breaks, for example, and the gas leaks, the flow in the opposite direction to the normal flow from the upstream side to the downstream side, that is, the reverse flow,
It occurs at least between the inside of the gas meter chamber and the downstream pipe. Moreover, this backflow cannot occur during normal gas use due to the structure of the gas meter.

[0015] In addition, even when gas leakage occurs in the downstream piping or the gas equipment further downstream, the above-mentioned backflow is an impossible event. That is, the backflow as described above is an event that occurs only when gas leakage occurs in the upstream pipe. Therefore, by detecting the occurrence of such backflow from the downstream side to the upstream side of the gas flow by the backflow detection means according to the present invention, it is possible to detect the occurrence of gas leakage in the upstream pipe. it can.

Secondly, the gas meter according to the present invention is a gas meter installed between an upstream pipe near a gas supply source and a downstream pipe near a gas appliance consuming the gas, wherein the upstream Gas fluid data measurement means for measuring fluid physical quantity data of the gas flow flowing in the positive direction from the pipe to the downstream pipe, and the measurement based on a function for associating the physical quantity data with the gas flow rate. A gas flow rate calculating means for calculating the flow rate of the gas from the data of the fluid physical quantity of the flow of the gas, wherein the gas fluid data measuring means further comprises: Gas flow data measuring means for measuring fluid physical quantity data of the reverse flow when the gas flows backward, and the gas flow rate calculating means further comprises the gas flow calculating means. When the flow data measurement data is measured by the gas fluid data measurement means, the gas flow data calculation means is also used as a backflow detection means for detecting a backflow of the gas based on the measurement data. It is a gas meter.

That is, by providing the gas flow data measuring means and the gas flow rate calculating means, which are used particularly in the guess type gas meter, with the function of detecting the backflow, at least the conventional guess type gas meter is used. It is possible to realize the backflow detecting means as described in the first aspect of the present invention by making effective use of the hardware resource by making only a slight change. In other words, in other words, the technology of the present invention is a technology that can be particularly preferably applied to a gas meter of a guessing method.

Third, the gas meter according to the present invention has the first
Alternatively, the gas meter according to the second aspect, further comprising a warning unit that warns that an abnormality has occurred in the upstream pipe based on the detection of the backflow of the gas by the backflow detection unit. It is a gas meter.

That is, if the backflow detecting means can detect the backflow of the gas, the occurrence of gas leakage in the upstream pipe detected thereby can be warned by the warning means. Alternatively, if a gas leak occurs in the upstream pipe, if the state of the gas leak is left as it is, the gas leak further proceeds and the danger becomes more serious, so the If it is detected that a gas leak has occurred, it not only issues a warning, but also immediately stops the gas flow between the regulator of the upstream pipe and the gas meter to further ensure safety. You should be able to.

Therefore, fourthly, in the gas meter according to any one of the first to third aspects, when the backflow detecting means detects the backflow of the gas, at least the upstream pipe based on the detection is detected. And a gas flow stopping means for stopping a gas flow from the adjuster to the downstream side based on the forward direction.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the gas meter according to the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, the gas meter 300 is provided between an upstream pipe 101 near a supply source of the gas 100 and a downstream pipe 102 near a gas device (not shown) that consumes the gas 100. 300, the upstream pipe 1
A gas fluid data measuring means 103 for measuring fluid physical quantity data of a flow of the gas 100 flowing in a positive direction from 01 to the downstream pipe 102, and a function for associating the physical quantity data with a gas flow rate. And a gas flow rate calculating means 104 for calculating the flow rate of the gas from the data of the fluid physical quantity of the measured gas flow. In such a gas meter 300, a main part of the characteristic configuration of the present invention is formed as follows.

That is, the gas fluid data measuring means 10
Further, when the gas 100 flows backward in the opposite direction to the forward direction, the gas fluid data measuring means 3 can measure fluid physical quantity data of the reverse flow.
03, and when the measurement data of the reverse flow is measured by the gas fluid data measurement means 103, the gas flow rate calculation means 104 detects the reverse flow of the gas 100 based on the measurement data. The gas flow rate calculating means 104 is also used as a backflow detecting means.

That is, for example, as shown in FIG. 1B, a breakage 200 occurs in the upstream pipe 101, which is a gas pipe on the upstream side of the gas meter, and a gas leak 201 of the gas 100 occurs in that portion. Has a flow in the opposite direction to the normal flow from the upstream side to the downstream side,
It is generated at least between the inside of the gas meter (a chamber 305a as shown in FIG. 2 described later) and the downstream pipe 101. Moreover, this backflow cannot occur when using a normal gas as shown in FIG. This is assured by the structure of the gas meter. Moreover, it goes without saying that the above-mentioned backflow cannot occur even when gas leaks occur in the downstream pipe 101 or in a gas device (not shown) further downstream. That is, the backflow of the gas 100 as described above is an event that occurs only when a gas leak occurs in the upstream pipe 101.

That is, when a gas leak occurs on the upstream side, the gas 100 must flow backward. Because,
Gas pressure at the gas meter and its upstream piping (this is P
g), the gas pressure downstream of the gas meter (this is Pu), and the atmospheric pressure (this is Pa), in general, the relationship of Pg>Pu> Pa holds. There should be. On the other hand, otherwise, the gas cannot be used on the downstream side, so that it does not function as a gas meter.

Since the gas meter and the gas pressure upstream and downstream of the gas meter are set so as to satisfy the relationship of Pg>Pu> Pa as described above, the gas leakage may occur due to breakage of the upstream pipe of the gas meter. When 201 occurs, the pressure difference with the outside air at that portion, that is, the pressure difference at which gas flows from the gas meter toward the upstream pipe;
When Pg-Pa is compared with Pu-Pa, which is a pressure difference for flowing a gas in the forward direction from the gas meter toward the downstream pipe, it is clear that the relationship Pg-Pa> Pu-Pa holds. That is, the gas 100 flows toward the upstream pipe rather than toward the downstream pipe. Therefore, when a gas leak occurs in the upstream pipe, a reverse flow occurs at least in the flow of the gas 100 from the gas meter chamber 305a to the upstream pipe due to the basic functional characteristics of the gas meter itself. become.

Therefore, the generation of such backflow from the downstream side to the upstream side of the gas flow is determined by the gas flow rate calculation means 104 having the function of the backflow detection means according to the present invention. By detecting based on the measurement, it is possible to detect that the gas leakage 201 has occurred in the upstream pipe 101.

Further, the gas meter 30 of the present invention
0 indicates that when the gas flow calculating means 104 having the function of the above-mentioned backflow detecting means detects the backflow of the gas 100,
Warning means 105 for warning that an abnormality has occurred in the upstream pipe 101 based on the detection result is further provided.

That is, the gas flow rate calculating means 104 which substantially has the function of the backflow detecting means also serves to
0 is detected, and the warning means 105 warns of the detected gas leak 201 in the upstream pipe. In the present embodiment, the warning unit 105 uses a segment type small liquid crystal display device that displays a numerical value of the integrated gas flow rate, and displays a warning such as “gas leak outside” on its display screen. However, it is needless to say that the type of warning is not limited to such a display alone. In addition, for example, an alarm sound may be generated, or the alarm sound and the display may be generated simultaneously.

Further, when a gas leak 201 occurs in the upstream pipe 101, if the state of the gas leak 201 is left as it is, the gas leak 201 proceeds further and the danger becomes more serious. Upstream piping 10
When it is detected that the gas leak 201 has occurred in the first pipe 1, not only the warning is given by the above-mentioned warning means 105 but also the gas flowing from the regulator 106 of the upstream pipe 101 to the gas meter 300 on the downstream side immediately. 100 flows
It is stopped by the gas flow stopping means 107. This allows
Further, safety can be ensured. In addition,
The gas flow stopping means 107 may be disposed as a means having a gas flow stopping function such as a shutoff valve, for example, at a portion near the outlet side of the regulator 106. However, the present invention is not limited to this, and it goes without saying that, for example, it may be arranged further upstream than the adjuster 106.

FIG. 2 is a diagram schematically showing an example in which the respective means in the present embodiment as described above are constructed around a CPU 500. As shown in FIG. 2, the chambers (airtight chambers) 305a and 305b are separated into two chambers with a partition wall therebetween, and the gas 100 flowing from the inlet on the upstream side is installed in the chambers 305a and 305b. The gas is supplied to a gas device (not shown) outside the gas meter through a gas outlet on the downstream side through the gas passage 103.

The gas fluid data measuring means 103 includes:
As shown in FIG. 2, a cylindrical gas passage 103 formed so that the gas 100 passes through the cylinder, and a gas 1 in the gas passage 103 which is arranged to face each other.
Ultrasonic wave transmitters / receivers 303 and 304 are provided for transmitting ultrasonic waves during the time 00 and measuring the propagation time T thereof. In FIG. 2, the arrow of the gas 100 indicates the case where the gas flows in the forward direction.

As shown in the figure, the gas passage 103 is provided with an ultrasonic wave transmitter / receiver 303, 304 which is arranged in an oblique arrangement with respect to the center line of the gas passage 103, that is, a so-called Z method. The propagation time T during which the ultrasonic wave propagates between the two is determined by the ultrasonic transmitter / receiver 303, 30
I / F (interface) of the electric signal detected in 4
The data is received by the CPU 500 via the circuit 400, and is subjected to arithmetic processing to generate data. In addition, the ultrasonic transmitter / receiver 303, 3
04 is not limited to only the Z-method arrangement. For example, as shown in FIG.
Needless to say, they may be arranged so as to face each other before and after.

The main part of the chamber of the gas meter according to the present embodiment has a hardware configuration as shown in FIG. It is the ultrasonic wave oscillators / vibrators 303 and 304 that execute the oscillation to vibration of the ultrasonic wave on the hardware by the gas fluid data measuring means 103, and convert the electrical signals detected by the ultrasonic wave / vibration devices into data. Gas flow rate calculating means 10 for processing the propagation time T based on the data
4 can be actually constructed inside the CPU 500.

If the distance (L) between the ultrasonic wave generator / receiver 303 and the ultrasonic wave transmitter / receiver 304 and the frequency of the ultrasonic wave are fixed, the propagation propagating through the gas 100 between the distances is fixed. By measuring the time T, the flow velocity v of the gas can be obtained based on this. And the obtained flow velocity v
, The flow rate of the gas at that time can be calculated. That is, the gas flow rate calculation means 104 calculates the function: ΔV = Fx (T) in accordance with the measured propagation time T of the ultrasonic wave.
Is calculated on the basis of the following equation. This calculation is actually executed inside the CPU 500 shown in FIG. 2, but at this time, a correspondence from T to ΔV; T → ΔV is a storage element in the CPU 500 or a storage element such as an EEPROM attached thereto. This is performed based on a table stored in advance in each of them (not shown). Thus the gas flow rate Δ
The calculation of V = Fx (T) to the calculation of the integrated gas flow rate are executed by the gas flow rate calculation means 104. That is, first, the gas flow rate ΔV = F corresponding to the time T measured at predetermined time intervals.
x (T) is calculated based on the table Fx. Subsequently, the integrated gas flow rate V is calculated by integrating the gas flow rate ΔV. The value of the gas integrated flow rate V thus obtained can be displayed on a gas integrated display counter (not shown) or the like.
Such a normal gas flow integrating function is the same as that of a conventional inferential gas meter.

The ultrasonic transmitter / receiver 30 as described above
Means for arithmetically processing the propagation time T based on the electric signal detected by the
Can be built inside. In the gas meter having such a structure, a function as a backflow detecting unit according to the present invention is further provided.

That is, the propagation time T of the ultrasonic wave measured between the ultrasonic wave transmitters / receivers 303 and 304 which substantially fulfills the function of the gas fluid data measuring means 103 is, for example, for simplicity of explanation here. In the case where the ultrasonic wave is emitted only in one direction from the ultrasonic wave transmitter / receiver 303 on the upstream side to the ultrasonic wave transmitter / receiver 304 on the downstream side, there is no gas leak on the upstream side and the normal state is maintained. When the gas 100 flows in the direction, the propagation time is measured as a propagation time shorter than the propagation time when the gas 100 is stopped, under the influence of the flow velocity v of the gas 100. Alternatively, when the propagation direction of the ultrasonic wave is opposite, the result is opposite to the above.

On the other hand, when a gas leaks on the upstream side and the gas 100 flows in a direction opposite to the forward direction, the ultrasonic wave is transmitted from the ultrasonic wave generator / receiver 303 to the ultrasonic wave generator 304. Then, the propagation time T is measured as a propagation time longer than the propagation time when the gas 100 is stopped under the influence of the flow velocity -v of the gas 100. Alternatively, when the propagation direction of the ultrasonic wave is opposite, the result is also opposite to the above.

Therefore, the ultrasonic transmitter / receiver 303, 304 which substantially fulfills the function of the gas fluid data measuring means 103
When the propagation time of the ultrasonic wave propagating between the gas flow changes from the gas flow v = 0 to the direction opposite to the case of the forward gas flow, a reverse flow of the gas 100 occurs inside the gas meter. Can be determined.

That is, here, the gas fluid data measuring means 10
3, the propagation time of the ultrasonic wave actually measured by the ultrasonic wave transmitters / receivers 303 and 304 (this is T),
The propagation time of the ultrasonic wave at the time of the gas flow velocity v = 0 recorded in advance in the CPU 105 or the like (this is referred to as T0) is compared, and ΔT = T−T0 is calculated. If (positive / negative) is opposite to the sign when the gas 100 is flowing in the positive direction, it is determined that backflow has occurred, that is, upstream hand gas leakage has occurred, and the function of the backflow detection means is determined. The determination can be made by the combined gas flow rate calculation means 104.

Next, an outline of the operation of the gas meter according to the embodiment of the present invention having the above-described general configuration, particularly for detecting a gas leak, will be described. The operation of measuring and calculating the gas flow rate in the normal state can be performed by following the same operation as the conventional operation by using the structure described above, so that the detailed description is omitted from the simplified description. I do.

FIG. 3 is a flowchart showing the outline of the operation for detecting gas leakage on the upstream side. At the time of normal gas use in which gas leakage does not occur on the upstream side, as described above, the gas fluid data measurement means 103 uses the ultrasonic wave propagation time T that changes in accordance with the flow velocity v of the gas 100.
Is measured (s1).

Then, the gas flow rate calculating means 104 calculates ΔT = T−T0 based on the measured propagation time T (s2). Then, the positive and negative signs of the calculated ΔT are
If the sign of the gas flow in the forward direction remains unchanged, it is assumed that no gas leakage has occurred on the upstream side, and the normal (that is, the same as the conventional) integrated operation of the integrated gas flow rate V is performed (s3).
N to s4). Then, at this time, if the gas meter 300
Needless to say, if a gas leak occurs on the downstream side of a conventional device, for example, a conventional pressure-type micro-leakage warning device functions similarly to the conventional device (not shown).

However, if the gas flow rate calculating means 104 detects that the positive / negative sign of the calculated ΔT is opposite to the sign of the gas flow in the positive direction, (s
3), the warning means 105 issues a warning based on the detection result of the gas flow rate calculating means 104 assuming that a gas leak has occurred on the upstream side of the gas meter 300 due to, for example, a broken gas pipe. s5).

At this time, further, based on the detection result of the gas flow rate calculating means 104, the gas flow stopping means 1
07 is the gas 100 flowing from the regulator 106 to the downstream side.
Is stopped (s6). And gas flow rate calculating means 1
The operation of the gas flow rate calculating means 104 is externally input to the gas flow rate calculating means 104 via an input device (not shown) such as a warning release button (not shown). When a reset command for canceling the warning occurrence state and the gas flow stop state is input (Y in s7), the backflow detection state as the backflow detection means of the gas flow rate calculation means 104 is reset (s8), and the normal flow is returned again. Return to the gas flow rate measurement operation and the like (s1).

In the present embodiment, the gas fluid data measuring means 103 and the gas flow rate calculating means 104 measure the propagation time T of the ultrasonic wave in the gas, and calculate
Although the case where V is calculated has been described, in addition to the propagation time T, for example, the propagation time Tu in the upstream direction and the propagation time Td in the downstream direction when the gas is flowing, like ΔT described above. It goes without saying that the difference Tu−Td is measured, and the gas flow rate calculation or the determination of the reverse flow of the gas flow may be performed by a method of calculating the gas flow rate ΔV based on the change in the difference Tu−Td. Also in this case, in particular, as a method of determining the backflow, a backflow of the gas 100 occurs when the value of the difference Tu−Td becomes a sign opposite to the sign (positive / negative) in the positive direction. Can be determined.

In this embodiment, the case of the so-called ultrasonic measurement method has been described, but the measurement method of the gas fluid data measurement means 103 is not limited to this. In addition, any gas fluid data measuring means of a type capable of detecting that the gas 100 flows in the opposite direction, such as a turbine flowmeter, a thermal flowmeter, or a differential pressure flowmeter, may be used in the present invention. Gas fluid data measurement means 1 according to
03 can be suitably used.

For example, in the case of a turbine flow meter, the gas 1
When a backflow of 00 occurs, the turbine blades will receive the backflow and rotate in the opposite direction to the forward flow described above. Therefore, by detecting a change in the phase or the like of the pulse waveform generated in the turbine flow meter in response to such reverse rotation by the gas flow rate calculating means 104 having the function of the reverse flow detecting means, the generation of the gas reverse flow, that is, upstream Gas leakage in the side piping can be determined.

In the present embodiment, the case where the technique of the present invention is applied to an ultrasonic measurement type gas meter is described, because the technique of the present invention is particularly suitable for application to a guess type gas meter. As a good example,
It goes without saying that the main configuration for detecting gas leakage upstream of the gas meter centering on the backflow detecting means according to the present invention can be applied to, for example, a so-called membrane gas meter which is of a mechanical measurement type. However, in that case,
In a mechanical gas meter such as a membrane gas meter, it is generally difficult, if not impossible, to accurately detect a backflow of gas with a conventional structure. It is difficult to construct a backflow detecting means. That is, as compared with the conventional hardware as a film-type gas meter, the ultrasonic wave transmitter / receiver 30 as described above is used as the backflow detecting means according to the present invention.
It is necessary to add 3,304 and the like. However, if such a backflow detecting means according to the present invention is provided,
This is preferable because the same effect of ensuring safety on the upstream side of the gas meter as in the above embodiment can be sufficiently obtained.

[0049]

As has been described in the detailed description, according to the present invention, a gas leak caused by a breakage of a gas pipe, especially on the upstream side of a gas meter, is immediately detected, and further a warning is issued. Further, it is possible to realize a gas meter that can warn of gas leakage due to a breakage of a pipe on the upstream side and stop the gas flow at that time to ensure safety.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a gas meter according to the present invention.

FIG. 2 is a diagram schematically illustrating an example of a case where each unit in the present embodiment as illustrated in FIG. 1 is built around a CPU 500;

FIG. 3 is a flowchart showing an outline of an operation of the gas meter according to the present invention for detecting a gas leak in an upstream pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 100 ... Gas 101 ... Upstream piping 102 ... Downstream piping 103 ... Gas fluid data measuring means 104 ... Gas flow rate calculating means 105 ... Warning means 106 ... Regulator 107 ... Gas flow stopping means 300 ... Gas meter (main body) 400 ... I / F circuit 500 CPU

Claims (4)

[Claims] 1. A method according to claim 1, wherein the gas is supplied between an upstream pipe near a gas supply source and a downstream pipe near a gas device that consumes the gas, and flows in a forward direction from the upstream pipe to the downstream pipe. What is claimed is: 1. A gas meter having gas flow rate measuring means for measuring a gas flow rate, comprising: a backflow detecting means for detecting a backflow when the gas flows backward in a direction opposite to the forward direction. 2. A gas meter installed between an upstream pipe near a gas supply source and a downstream pipe near a gas device consuming the gas, wherein the gas meter goes from the upstream pipe to the downstream pipe. Gas fluid data measurement means for measuring fluid physical quantity data of the gas flow flowing in the positive direction, and a fluid flow rate of the measured gas flow based on a function for associating the physical quantity data with the gas flow rate. A gas flow rate calculating means for calculating the flow rate of the gas from the data of the physical quantity, wherein the gas fluid data measuring means further comprises: when the gas flows backward in the opposite direction to the forward direction. Gas flow data measurement means for measuring fluid physical quantity data of the reverse flow, wherein the gas flow rate calculation means further comprises: When measured by a gas fluid data measurement means, a gas meter, which is a gas flow rate calculation means also serves as a backflow detecting means for detecting a backflow of the gas based on the measured data. 3. The gas meter according to claim 1, wherein, when the backflow of the gas is detected by the backflow detecting unit, a warning unit that warns that an abnormality has occurred in the upstream pipe based on the detection. A gas meter, further comprising: 4. The gas meter according to claim 1, wherein when a backflow of the gas is detected by the backflow detecting means, at least a regulator in the upstream pipe is used to detect the backflow based on the detection. A gas meter further comprising gas flow stopping means for stopping a gas flow toward a downstream side with respect to the reference.