JP2001165720A - Method and device for detecting flow rate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a fine flow rate which is relatively difficult to detect and to estimate the cause of a fine leak like this. SOLUTION: Fluid flow passage in which fluid flows is equipped with a cutoff mechanism 6 which cuts off the fluid and flow rate measuring means 7 and 10 which measure the flow rate of the fluid flowing inside in order from the upstream side. To detect the flow rate of the fluid flowing downstream, the cutoff mechanism 6 is closed and then opened and whether or not there is a flow in the closure state or its flow rate is found from the outputs of the flow rate measuring means 7 and 10 in the closure state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention provides a flow rate measuring means for measuring a flow velocity in a fluid flow path to be measured.
The present invention relates to a technique for measuring and detecting a minute flow rate region near or below the lower limit of the flow rate measurement by the flow rate measuring means.

[0002]

2. Description of the Related Art For ease of explanation, a gas meter provided with a fluid element provided in a city gas supply pipe of each household will be described below. For the purpose of detecting the flow rate of the amount of city gas consumed in each home, a gas meter, which is a type of flow rate detection device, is provided at the entrance of each home, and the gas consumption is detected by this meter.
When a large amount of gas flows due to an abnormality in a gas supply system or the like in a house, a shutoff device (cutoff mechanism) for shutting off a flow path is provided in the gas meter to shut off gas supply.
In such a state of supplying city gas to each household, for example, a minute leak may occur in a piping system or the like downstream of the gas meter. Conventionally, such a gas leak is usually detected by using a gas sensor to detect a gas leak into a room, and in the case of a film-type gas meter, by measuring a long-term integrated flow rate.

[0003]

It is preferable that such a gas leak is detected immediately, not on the downstream side of the meter but on the supply upstream side at the entrance to each home. However, since the amount of such gas leakage is relatively small, there is a case where the flow rate measurement means is actually smaller than the lower limit flow rate of the flow rate measurement means, except when an integrating meter such as a membrane gas meter is used. The fact is that detection cannot be performed by itself. Further, the detection of gas leakage by a gas sensor or the like does not make it possible to know the absolute value of the amount of leakage.
In addition, even if the method of closing the shut-off valve provided at each home entrance and measuring the pressure drop on the downstream side in the closed state is adopted as in the conventional periodic inspection work, the leakage The absolute value of the quantity cannot be determined. Furthermore, when the above-described integration method is employed, it takes several tens of minutes for detection. On the other hand, when a method of measuring the leakage in the gas supply system by closing the flow path is adopted,
It is not possible to distinguish between the downstream leakage described above, the passage caused by the abnormality of the shutoff mechanism provided in the gas meter, and the occurrence of both. In such a case, it is preferable that the cause of occurrence and the situation can be quantitatively specified. However, a technology capable of performing such specification has not been obtained at present. An object of the present invention is to provide a technique capable of detecting a minute flow rate, which is relatively difficult to detect, and estimating the cause of such a minute leak.

[0004]

According to the present invention, there is provided a fluid flow path through which a fluid flows, a shut-off mechanism for shutting off the flow path, and a flow rate measuring means for measuring a flow rate of the fluid flowing through the inside. And means for detecting the flow rate of the fluid flowing to the downstream side.The characteristic means of the flow rate detection method includes: closing the shut-off mechanism, then opening the shut-off mechanism, and performing the opening operation. The purpose of the present invention is to determine the presence or absence of a generated flow in the closed state or the flow rate thereof from the output of the flow rate measuring means. In this detection method, the shutoff mechanism provided in the gas supply system is temporarily maintained in a closed state. In this closed state, if there is a leak downstream of the shut-off mechanism, the gas pressure downstream of the shut-off mechanism decreases due to the gas leak. Here, when the shut-off mechanism is restarted, a large flow rate temporarily flows due to the pressure drop caused by the leak on the downstream side in association with the opening operation. The flow rate can be set to an amount (about 5 cc) at which the flow rate can be measured by the flow rate measuring means due to the maintenance time of the closed state (for example, 6 to 20 seconds). You can know the absolute amount of flow. Therefore, the flow rate of the generated flow is a so-called integrated flow rate, and the output from the flow rate measuring means is output as a flow rate per unit time. These values are used to increase the supply pressure upstream of the shutoff mechanism from 980 to 248.
0 Pa (100 to 250 mmAq), the calculated value when the downstream representative pressure at the time of the opening operation is 490 Pa (50 mmAq), and the volume on the downstream side is 1 liter. .4 cc can be detected. As a flow rate detection device using the above flow rate detection method, a flow path through which a fluid flows inside, a shutoff mechanism that shuts off the flow path, and a flow rate measurement unit that measures the flow rate of the fluid flowing inside, from the upstream side Prepared in the order described, to constitute a flow rate detection device that detects the flow rate of the fluid flowing downstream, after closing the shut-off mechanism, with a flow rate measurement opening and closing control means to open the shut-off mechanism, It is preferable to include a generated flow deriving unit that derives the presence or absence of a generated flow in the closed state from the output of the flow measurement unit accompanying the opening operation or a derived flow. The functions of the shut-off mechanism and the flow rate measuring means are the same as those in the flow rate measuring method described above, but in this device, the shut-off mechanism is operated to the closed state by the flow rate opening / closing control means, and thereafter, Perform operation to open. Then, the generated flow deriving means can derive the flow accompanied by the opening operation after the restart from the output from the flow measuring means, and determine the presence or absence of the generated flow. Here, in the flow rate measuring means, by performing a closed state maintenance when there is a leak or the like on the downstream side,
This can be measured as the flow rate exceeding the lower limit of measurement.

When the detection is performed as described above, the timing of the opening operation from the closed state to the open state is set by the elapsed time from the closing operation, the downstream representative pressure downstream of the shut-off mechanism or the downstream representative pressure. , Based on one or more time differential values of the downstream representative pressure. That is, as the flow rate detection device, the setting of the opening operation timing from the closed state to the open state by the flow rate measurement opening / closing control means is the elapsed time from the closing operation, the representative pressure downstream from the shut-off mechanism. Downstream representative pressure or
It is preferable to perform the determination based on at least one of the time differential values of the downstream representative pressure. When adopting such a method, the maintenance time of the closed state is set as a predetermined time empirically obtained, and when the predetermined time has elapsed since the closing operation, the operation is restarted. By appropriately or empirically setting a preferable time suitable for the measurement purpose, it is possible to accurately capture the generated flow for the detection target purpose. On the downstream side of the flow detection device, the minimum supply pressure required on the downstream side (for example, 980 Pa (100
mmAq) may exist, but the downstream supply pressure can be maintained by restarting the shut-off mechanism in a state where the downstream representative pressure reaches such a pressure. Further, the flow downstream of the flow rate detection device is temporarily affected by this operation in accordance with the closing operation of the shut-off mechanism, causing a pressure change. This state is reduced by stabilizing the downstream side. Therefore, when such a stable state is reached,
By setting the restart timing, it is possible to set a closed state maintenance time representing the state of the system.

In the present application, the flow rate measurement accompanying the opening operation is performed after the restarting operation of the shut-off mechanism, and is used to determine the flow rate of the generated flow from the output of the flow rate measuring means accompanying the opening operation. The flow rate (integrated flow rate) that flows from the opening operation timing until the state downstream of the shut-off mechanism is restored to the state immediately before the closing operation, and the output from the opening operation timing until the output from the flow rate measurement unit is no longer obtained. The flow rate (integrated flow rate) can be obtained as the flow rate (integrated flow rate) or the flow rate (integrated flow rate) that flows until a predetermined time has elapsed from the opening operation timing. That is, in terms of the device, the generated flow deriving means determines the flow rate of the generated flow from the output of the flow measuring means accompanied by the opening operation. The flow rate (integrated flow rate) that flows until the state immediately before the closing operation is restored, the flow rate (integrated flow rate) that flows from the opening operation timing until the flow rate measurement output by the flow rate measuring means is no longer obtained, or the opening operation timing It is preferable to determine the flow rate of the generated flow as a flow rate (integrated flow rate) that flows until a predetermined time elapses. Originally, the present application has a problem with a small flow rate that cannot be measured by the flow rate measuring means, so after the restarting operation of the shut-off mechanism, the flow rate is measured by the flow rate measuring means, and the flow rate becomes lower than the measurement limit, It is up to the point where the output from the flow rate measuring means can no longer be obtained. In this case, since the time from the closing operation in which such a situation occurs can be known empirically in advance, it may be performed in a preset short time for obtaining the flow rate of the generated flow, or the downstream representative pressure. The pressure (state) may be restored to the pressure (state) before the closing operation while checking the state of (1).

In the flow rate detection method described above, it is preferable to obtain a flow rate per unit time in the closed state from the flow rate obtained in the open state based on the maintenance time of the closed state. That is, in terms of the device, based on the maintenance time of the closed state from the closing operation to the opening operation, based on the flow rate of the generated flow derived by the generated flow rate deriving means, the flow rate per unit time in the closed state is calculated. A means for deriving a leak amount to be obtained is provided. Although the presence of a leak on the downstream side causes a pressure drop on the downstream side of the detection device, the flow rate caused by the restarting operation after maintaining the constant closed state effectively reduces the downstream flow rate within the closed state maintaining time. It can be considered as a flow that leaked out of the road. Therefore, the flow rate per unit time in the closed state can be obtained by the above method.

In the normal use state, there are provided a normal mode in which measurement is performed at a normal cycle and a high-speed mode in which measurement is performed at a cycle faster than the normal cycle. Preferably, the flow measurement is performed in the high-speed mode. Here, the normal use state means, for example, a case where the flow rate is within the detection range of the flow rate detection means and a normal output from this means is obtained. Then, in this state, the flow rate is measured in the normal mode with a relatively long cycle to confirm that no abnormality has occurred.
On the other hand, for example, when the flow rate is lower than the detection range of the flow rate detection means, detection with a closing operation of the shutoff means and a subsequent opening operation is performed in a relatively short cycle. By doing so, it is possible to reliably measure the flow rate of a relatively small flow rate caused by leakage or the like in a short time. By the way, when this method is adopted, the flow rate detecting device described so far includes a normal mode for measuring the flow rate at a normal cycle, and a high-speed mode for measuring the flow rate at a higher cycle than the normal cycle, and from the closing operation. The flow rate measurement in the open state following the opening operation is performed in the high-speed mode. Therefore, by performing the flow rate detection in the high-speed mode at a predetermined time, for example, it is conceivable that a leak or the like has occurred. By confirming the presence or absence of the generated flow in the closed state accompanied by the subsequent opening operation, it is possible to accurately detect a leak or the like.

Now, in a system such as the present application, there is a shut-off mechanism. However, it is possible to determine whether there is a passage in the shut-off mechanism or a leak from the inside of the system to the outside. is important. Normally, the fluid behavior in the system in which the flow detecting device is provided follows the following equation. For a model as shown in FIG. 4, the pressure at the downstream position of the flow detection device (representative downstream pressure in the present application) is P1, the supply pressure is P2, and the conductance of leakage (leakage downstream from the flow detection device) is K1. (Constant), K2 (Constant) is the conductance passing through the shutoff mechanism, Q is the flow rate flowing into and out of the pipe downstream of the flow rate measuring device, and V is the pipe volume.

## EQU1 ## dP1 / dt = Q / V (1)

Q = −K1 × sqrt (P1) + K2 × sqrt (P2−P1) The first term of the second equation is the flow rate generated due to leakage to the outside, and the second term is the flow rate generated due to passage through the shutoff mechanism. Considering this equation, when there is no passage through the shut-off mechanism and the second term is 0, the first equation can be converted into dP1 / dt / sqrt (P1) / V = -K1 (constant), and the flow rate is determined by the outlet. Be linear with respect to the square root of pressure. When the second term is not 0 due to the passage of the shutoff mechanism, the linearity is not obtained. Therefore, from the relationship between the two (the decreasing speed of the downstream representative pressure and the downstream representative pressure),
It is determined whether the leakage is caused only or the passing-through occurs. That is, the fluid flow path in which the fluid flows through the inside, a blocking mechanism for blocking the flow path, and a flow rate measuring means for measuring the flow rate of the fluid flowing inside is provided in order from the upstream side, and the flow rate of the fluid flowing to the downstream side is determined. A flow rate detection device for detecting, the relationship between the rate of decrease of the downstream representative pressure, which is the representative pressure downstream of the shut-off mechanism, and the downstream representative pressure is obtained in a closed state of the shut-off mechanism, and the downstream representative If the configuration is provided with the first generated flow rate cause deriving means for deriving the cause of the pressure change, from this relationship, for example, it is determined whether there is an element that passes through the shutoff mechanism, and as a result, the generated flow The cause can be derived.

Further, the flow rate of each generated flow corresponding to a different closed state maintaining time is obtained by the generated flow rate deriving means,
It is also preferable to include a second generated flow cause deriving unit that derives a cause of the generated flow from a mutual relationship between the flow rates of the generated flows corresponding to the different closed state maintaining times. Shut-off mechanism,
The functions of the flow rate measuring means, the flow rate opening / closing control means, and the generated flow rate deriving means are the same as those described above. In this apparatus, at least one pair of flow rates generated at different closed state maintenance times is obtained by operating the flow rate measurement opening / closing control means and the generated flow rate derivation means by the second generated flow rate cause deriving means. The flow rate of the fluid that leaks from the downstream side to the outside in the state with the flow path cutoff is exponential as shown in the above-described first and second equations if there is no passage through the cutoff mechanism. Indicates a change. That is, it is possible to determine whether there is only a leak from the flow rate flowing at different closed state maintaining times, and as a result, it is possible to determine whether there is a passage or the like. The second generated flow cause deriving means performs this determination and specifies the cause of the generated flow.

Further, a relation index between the downstream representative pressure drop from the closing operation to the opening operation and the flow rate, which depends on the cause of the generated flow, is provided in advance, and based on the relation index,
Deriving the cause of the generated flow from the relationship between the generated flow derived by the generated flow deriving means and the downstream representative pressure drop from the closed state to the open state (immediately before the opening operation). It is also a preferable embodiment to provide a generated flow cause deriving unit. The functions of the shutoff mechanism, the flow rate measuring means, the flow rate opening / closing control means, and the generated flow rate deriving means are the same as those described above. As described above, the reduction amount of the downstream representative pressure until immediately before the closing operation and the restarting operation of the shutoff mechanism and the flow rate of the generated flow accompanying the closing operation and the restarting operation of the shutoff mechanism are caused by the cause of the generated flow ( The behavior differs depending on the cause of leakage on the downstream side of the detection device or the cause of passage through the shut-off mechanism).
Satisfies a unique relationship as can be seen from the equation. Therefore, it is assumed that such a relation index is prepared in advance or the flow rate detecting device is provided with a learning function so that the relation index is acquired by learning and stored. Then, by comparing such a relation index with the actually measured value, the cause of the generated flow can be derived from the comparison result by the third generated flow cause deriving means. In this case, by judging which of the causes is closer to the actual value,
You can make decisions.

[0012]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a gas supply destination 1 in which a flow detection method of the present application and a flow detection device using this method are provided.
It shows a gas supply system to (for example, a home or a factory). To each supply destination 1, for example, gas is supplied from a low-pressure pipe 3 buried in a road 2 via a take-out pipe 4. A so-called gas meter 5 as a flow rate detection device is disposed at the entrance of each supply destination 1. In this meter 5, a fluidic element in which measurement of the amount of gas supply to each supply destination 1 is provided is provided. 7 is performed. Further, for example, a shut-off valve 6 serving as a shut-off mechanism is provided in the gas meter 5 so that an emergency shut-off can be performed in the event of gas leakage at a portion downstream of the meter 5. I have. Such a fluidic element 7 is a known one. By measuring the frequency of an oscillating flow that alternately flows on both sides of a target 8 provided approximately at the center of the fluidic element 7,
Can be detected. Here, in the fluidic element 7, the oscillation lower limit with respect to the flow rate is determined for each element. Since the fluid oscillation cannot be detected for the flow rate less than the oscillation lower limit as shown in FIG. On the other hand, the flow rate below the oscillation lower limit is measured using a flow meter (not shown). In the present application, it is possible to measure the flow rate in such a relatively small flow rate range without providing a flow meter. A predetermined portion of the fluidic element 7 is provided with a pair of output units 9 for detecting oscillation. These pair of output units 9
The pressure difference between the gas pressures between
The frequency of the vibration is obtained, and a converter 10 is provided which determines the flow rate of the gas flowing through the element 7 from this frequency and a relation index between the known frequency and the flow rate. The output (flow rate per unit time) of the converter 10 is controlled by the control unit 1 of the meter.
And sent to the control unit 11 for later use. In the present application, the fluidic element 7 and the converter 10 are collectively referred to as a flow rate measuring means. In this flow rate measurement, when the relationship index of FIG. 2 is used, the value (flow rate) on the horizontal axis is obtained from the value (frequency) on the vertical axis. Here, in the present application, the detection mode for determining the flow rate (integrated flow rate) from the output of the converter 10 is as follows.
It is possible to perform a normal mode (flow rate detection is performed, for example, every 30 minutes to 1 hour) and a high-speed mode (flow rate detection is performed, for example, about every 10 seconds). Further, in the flow rate detection in the high-speed mode, in order to obtain flow rate information, the processing speed in the converter 10 is increased and a higher-speed digital noise filter is applied.
The flow rate can be continuously detected immediately after the opening operation following the closing operation of the shutoff valve 6 described later. Further, in the high-speed mode, the time interval of the pressure measurement to be performed separately is also made fine, and a predetermined determination shown below can be made based on the pressure measurement data at the fine time interval. On the other hand, in the above-mentioned normal mode, in the detection after the opening operation of the shut-off valve, the count is normally excluded for a certain time immediately after the switching, and the flow rate in the time range of the count exclusion is estimated by means such as interpolation. Thus, the power consumption during the calculation is suppressed. After performing the closing operation of the shut-off valve 6 described below, the restart operation of the shut-off valve 6 is performed,
When the flow rate measurement is performed, a structure for performing the flow rate measurement in the high-speed mode is adopted.

The shut-off valve 6 is a general shut-off valve, which is used for emergency shut-off of a flow path when a large flow rate flows downstream of the gas meter 5 and when the gas supply is stopped for a long time. Then, the shut-off valve 6 is maintained in the closed state, and the gas supply is stopped. The opening and closing operation of the shutoff valve 6 is in accordance with the opening and closing command. Even with the shut-off valve 6, there is a case where a through-hole occurs to a degree that does not usually cause a problem.

Various gas appliances 12 are provided on the downstream side of the gas meter 5 to supply gas and serve, for example, heating. Even at such a downstream side of the gas meter 5, sometimes leakage may occur.

The above is a description of the schematic structure of the shut-off valve 6, the flow rate measuring means 7, and the gas consuming unit 13 located downstream of the flow rate measuring means 7 which are the subject of the present application.
The feature configuration of the present application will be described. The flow rate measuring means 7
A pressure gauge P for measuring the gas pressure (referred to as a downstream representative pressure) of the gas flowing out of the gas meter 5 is provided on the downstream side, and the measurement result of the pressure gauge P is also sent to the control unit 11. Is adopted.

The controller 11 controls the flow rate measurement to close the shutoff valve 6 at a predetermined timing and to open the shutoff valve 6 after a predetermined time (referred to as a minute flow rate measurement time) has elapsed. Opening / closing control means 14 is provided. Further, the flow rate of the gas passing through the element 7 (until the flow rate becomes less than the lower limit flow rate and the output cannot be obtained by the flow rate measurement means) until a predetermined time (the flow rate becomes less than the lower limit flow rate within this time) starting from the timing when the minute flow rate measurement time has elapsed A generated flow deriving means 15 for calculating and deriving the integrated flow) from the output of the converter 10 is provided. The flow rate derived by the generated flow rate deriving means 15 represents a change occurring between the fluid supply systems sandwiching the shutoff valve 6 during the minute flow rate measurement time (for example,
If there is a leak downstream of the element 7, the leak amount is obtained. Further, the control unit 11 has a relation between the flow rate of the generated flow derived by the generated flow rate deriving means 15 and the minute flow measurement time (for example, the flow rate of the generated flow / the minute flow measurement time).
And a leak amount deriving means 16 for deriving an absolute value of the leak amount per unit time from the above. By adopting such a configuration, the shut-off valve 6 is closed for a certain period of time by the flow rate measurement opening / closing control means 14 and then restarted. By deriving, the presence or absence of the generated flow and the flow rate measurement of the generated flow can be performed.

Now, in the system in which the gas meter 5 is disposed as in the present application, it is also possible to determine whether there is a passage in the shut-off valve 6 or a leak from the inside of the system to the outside. This is an important technical issue. Hereinafter, this configuration will be described. The control unit 11 obtains, as an index, a time change of a value obtained by dividing a decrease rate of the downstream representative pressure measured by the pressure gauge P by a square root of the pressure measured at that time, and the index is in a constant state. The first flow rate cause deriving means 17 is provided to determine whether or not there is a passage through the shut-off valve 6 if it is not constant, or not if it is not constant. Therefore, this means 17 can determine that there is no passage through the shut-off valve 6 when the index does not change.

Further, the control section 11 is operated by a flow rate measurement opening / closing control means 14 and a generated flow rate deriving means 15,
The minute flow rate measurement time is changed, the flow rate at each measurement time is measured by the flow rate measurement after resumption, and the relationship between the two flow rates depends on whether or not the flow rate change tendency attributable only to the downstream leak is indicated. In the case of the flow rate change tendency caused only by the downstream leak, the second generated flow rate cause deriving means 18 which determines that only the leak has occurred and determines that there is a passage of the shutoff valve if the tendency is not satisfied. It has. When the means 18 is provided, the presence or absence of the passage through the shutoff valve 6 can be determined from the flow rate obtained by the opening operation after the closing operation of the shutoff valve.

The control unit 11 further includes, at least when the shut-off valve 6 passes through, a pressure drop amount measured by the pressure gauge P after the closing operation.
A storage means 100 for storing the relationship between the generated flow and the flow rate is provided. In accordance with a relation index stored in the storage means 100, a predetermined closing operation is performed by operating the flow rate measurement opening / closing control means 14 and the generated flow rate deriving means 15. The third generated flow cause derivation that determines which relation index the relation between the flow rate of the generated flow detected in the operation and the subsequent opening operation and the amount of pressure drop matches, and specifies the cause of the generated flow Means 19 are provided. When this means 19 is provided, it can be determined by this means whether or not the cutoff valve 6 has passed through.

Therefore, in the flow rate detecting device of the present invention,
When a closing operation and a subsequent opening operation are performed, the presence or absence of a generated flow, the flow rate of the generated flow (integrated flow rate), and the flow rate per unit time within the closed state maintaining time, the first, second, and third The result of the cause determination by the generated flow cause deriving means 17, 18, 19 can be obtained from the input / output device 200. further,
Through the input / output device 200, the closed state maintaining time can be input and the flow measurement time of the generated flow in the open state (integrated flow measurement time) can be input. Further, a judgment index used in the third generated flow rate deriving means 19 can be input.

[Another Example] (a) In the above embodiment, the gas meter is provided with a single fluidic element, the flow rate is detected using the fluidic element, and the detection of this element is performed. Although the state of the gas supply system was determined based on the result, as shown in FIG. 3, the structure of the detection system in the gas meter was configured to include a bypass for the fluidic element, and was disposed on the bypass. The detection area of the entire gas meter may be shifted upstream by opening and closing the shutoff valve. (B) In the above embodiment, an example in which a fluidic element is provided as a flow rate measuring means has been described. However, in the present application, the flow rate measuring means is limited to one having a fluidic element. Is not something that can be done. Ultrasonic flow meters can also be used. However, in the case of using a fluidic element, since there is a relatively clear lower limit of transmission, the present invention can be suitably applied to a flow rate detecting device using such an element. (C) In the above embodiment, the setting of the opening operation timing from the closed state to the open state is performed based on the elapsed time from the closing operation. The determination may be performed based on pressure or one or more time differential values of the downstream representative pressure. (D) Further, in the above embodiment, in order to obtain the flow rate of the generated flow from the output of the flow rate measuring means in the open state, the flow is performed until a predetermined time elapses from the opening operation timing. The flow rate, or the flow rate from the opening operation timing until the output from the flow rate measuring means is no longer obtained, was obtained, but the state downstream of the shut-off mechanism from the opening operation timing is the state immediately before the closing operation. As the flow rate until it recovers to
The flow rate of the generated flow may be obtained. (E) In the above embodiment, the example in which the shut-off valve is adopted as the shut-off mechanism has been described. However, instead of the valve, any one that can exhibit the shut-off function in the fluid flow path may be used. good.

[0022]

Therefore, by employing the method of the present invention, the detection device alone can detect a minute flow rate where flow rate cannot be detected and estimate the cause of the occurrence of such a minute flow rate. It became possible.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a gas meter of the present application.

FIG. 2 is a diagram showing characteristics of a fluidic element.

FIG. 3 is a diagram showing a configuration of a fluidic element having a bypass flow path.

FIG. 4 is a model diagram of a gas supply system via a flow detection device.

[Explanation of symbols]

 Reference Signs List 5 gas meter (flow rate detecting device) 6 shut-off valve 7 fluidic element (flow rate measuring means) 10 converter (flow rate measuring means) 14 flow rate open / close control means 15 generated flow rate deriving means 16 leak amount deriving means 17 first generated flow rate cause Derivation means 18 Second generated flow cause deriving means 19 Third generated flow cause deriving means P Pressure gauge

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01M 3/26 G01M 3/26 M 3/28 3/28 C (72) Inventor Hiroshi Matsushita Osaka-shi, Osaka Osaka Gas Co., Ltd. 4-1-2, Hirano-cho, Chuo-ku (72) Inventor Shuichi Okada 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka-shi F-term (reference) 2F030 CA03 CB02 CC13 CE02 CE04 CF05 CF09 CF11 CF20 2F035 DA14 2G067 AA14 BB22 CC04 DD02 DD04 EE04 EE09

Claims (9)

[Claims] 1. A fluid flow path in which a fluid flows inside, a shut-off mechanism for shutting off the flow path, and a flow rate measuring means for measuring a flow rate of the fluid flowing inside the flow path are arranged in order from the upstream side, and the fluid flowing downstream. A flow detection method for detecting the flow rate of the flow rate, wherein after the shut-off mechanism is closed, the shut-off mechanism is opened, and the presence or absence of a generated flow in the closed state is determined based on an output of the flow rate measuring means accompanying the opening operation. Or a flow rate detection method to find the flow rate. 2. A fluid flow path in which a fluid flows inside, a shut-off mechanism for shutting off the flow path, and a flow rate measuring means for measuring a flow rate of the fluid flowing inside are provided in order from an upstream side, and a fluid flowing downstream. A flow rate detecting device for detecting the flow rate of the flow rate, comprising: a flow rate measurement opening / closing control means for closing the shut-off mechanism and then opening the shut-off mechanism, and an output of the flow rate measuring means accompanying the opening operation. A flow rate detecting device provided with a generated flow rate deriving means for deriving the presence or absence of the generated flow in the closed state or the flow rate thereof. 3. The setting of the opening operation timing from the closed state to the open state by the flow rate measurement opening / closing control means is performed by setting an elapsed time from the closing operation and a downstream pressure that is a representative pressure downstream of the shutoff mechanism. 3. The flow rate detection device according to claim 2, wherein the detection is performed at one or more of a representative pressure and a time differential value of the downstream representative pressure. 4. When the generated flow deriving means obtains the flow rate of the generated flow from the output of the flow measuring means accompanying the opening operation, the state downstream from the shut-off mechanism from the opening operation timing is immediately before the closing operation. The flow rate until the state returns to the state, the flow rate from the opening operation timing until the output by the flow rate measuring means is no longer obtained, or the flow rate until the predetermined time has elapsed from the opening operation timing. 4. The flow detecting device according to claim 2, wherein a flow rate of the flow is obtained. 5. A leak for obtaining a flow rate per unit time in a closed state from a flow rate of a generated flow derived by the generated flow rate deriving means based on a maintenance time of the closed state from the closing operation to an opening operation. The flow rate detecting device according to claim 4, further comprising a quantity deriving unit. 6. A fluid flow path in which a fluid flows in a fluid flow path, wherein a shut-off mechanism for shutting off the flow path and flow rate measuring means for measuring a flow rate of the fluid flowing in the flow path are provided in the stated order from the upstream side. A flow rate detecting device for detecting a flow rate of the downstream representative pressure, which is a representative pressure downstream of the shut-off mechanism, and a time-dependent change in the relationship between the downstream representative pressure and the closed-state of the shut-off mechanism. And a first flow rate cause deriving means for deriving the cause of the change in the downstream representative pressure. 7. A flow rate of each generated flow corresponding to a different closed state maintaining time is obtained by the generated flow rate deriving means, and the flow rate of each generated flow corresponding to the different closed state maintaining time is determined based on a mutual relationship between the flow rates of the generated flows. The flow rate detecting device according to any one of claims 2 to 5, further comprising a second generated flow rate cause deriving unit configured to derive a cause of the generated flow. 8. A method according to claim 1, further comprising: providing a relationship index between the amount of decrease in the downstream representative pressure from the closing operation to the opening operation and the generated flow rate, which depends on the cause of the generated flow, based on the relationship index. From the relationship between the flow rate of the generated flow derived by the generated flow deriving means and the amount of decrease in the downstream representative pressure measured from the closing operation to the opening operation, a third generated flow rate for deriving the cause of the generated flow Claim 2 provided with a cause deriving means.
The flow rate detection device according to any one of claims 5 to 7, or 7. 9. A normal mode for measuring a flow rate at a normal cycle, and a high-speed mode for measuring at a higher cycle than the normal cycle, wherein the measurement of the open state accompanying the opening operation from the closing operation is performed at the high-speed mode. The flow rate detection device according to any one of claims 2 to 8, wherein the flow rate detection is performed.