JP2002168663A - Flow measurement device and leak detection device - Google Patents

Abstract

(57) [Problem] To provide a flow rate measuring device and a leak detecting device which improve leak detection accuracy by accurately detecting a gas leak without being affected by a gas temperature. SOLUTION: While the use judging means 5a-2 judges that it is not, a first timing means 5a-3 starts measuring a first predetermined time. The gas pressure (hereinafter referred to as P1) detected by the leak detecting means 5a-4 at the time when the first time measuring means starts timing.
/ Gas temperature detected at the start of timing (hereinafter T1)｝ ≠
When {gas pressure (hereinafter, P2) detected at the end of timing by the first timing means / gas temperature (hereinafter, T2) detected at the end of timing}, a gas leak is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate measuring device having a function of detecting gas leakage in a gas supply path, and a leak detection device for detecting gas leakage in a gas supply path.

[0002]

2. Description of the Related Art As a flow measuring device incorporating the above-mentioned leak detecting device, a gas shutoff device as disclosed in Japanese Patent Application Laid-Open No. 10-288337 has been proposed. This gas shut-off device detects a gas leak when a gas pressure exceeds a predetermined value or a gas flow is detected while a gas supply path is shut off by a shut-off valve.

Further, a leak detecting device as disclosed in Japanese Patent Application Laid-Open No. 9-72500 has been proposed. In this leak detection device, pressure sensors are installed at two places separated from each other, and when gas is not used, a leak is detected when the pressure difference exceeds a predetermined value.

[0004]

By the way, in the gas supply path, even if the gas supply path is not leaked, if the gas temperature changes, the gas pressure changes with the change. I will. In addition, gas may flow locally due to the gas pressure change. For this reason, the gas shut-off device disclosed in Japanese Patent Laid-Open No. 10-288337 is
There has been a problem that a gas pressure change or a gas flow accompanying a gas temperature change is erroneously detected as a result of a gas leak, and the gas leak cannot be accurately detected.

On the other hand, in the leak detecting device disclosed in Japanese Patent Application Laid-Open No. 9-72500, for example, if the gas temperature is different at a place where the pressure sensors are separated from each other, this temperature difference is generated even though no gas leak occurs. A pressure difference equal to or greater than a predetermined value occurs between the two pressure sensors. Therefore, the leak detecting device erroneously detects the pressure difference due to the temperature difference as a gas leak, and in this case, there is a problem that the gas leak cannot be detected accurately.

Accordingly, the present invention focuses on the above-described problems, and detects a gas leak accurately without being affected by gas temperature, thereby improving the accuracy of leak detection. It is an object to provide a leak detection device.

[0007]

The invention according to claim 1 for solving the above-mentioned problems is provided in a gas supply path 10 as shown in a basic configuration diagram of FIG. Flow measuring device provided with a passing flow rate measuring means 5a-1 for measuring a passing flow rate of a gas supplied to a combustor through a use judging means 5a for judging whether or not the combustor uses the gas. -2, a temperature detecting means 15 for detecting a gas temperature in the gas supply path, a pressure detecting means 16 for detecting a gas pressure in the gas supply path, and the use judging means, A first timer 5a-3 for starting a first predetermined time, and a value obtained by dividing the gas pressure detected at the start of the time by the first timer by the gas temperature detected at the start of the time. And the first timing means Leak detection means 5a-4 for detecting a gas leak when the gas pressure detected at the end of the time measurement is not equal to a value obtained by dividing the gas temperature detected at the end of the time measurement. There is a characteristic flow rate measuring device.

According to the first aspect of the present invention, while the use judging means judges that the answer is no, the first timing means starts measuring the first predetermined time. The gas pressure (hereinafter referred to as P1) detected by the leak detecting means at the time when the first time measuring means starts timing.
/ Gas temperature detected at the start of timing (hereinafter T1)｝ ≠
When {gas pressure (hereinafter, P2) detected at the end of timing by the first timing means / gas temperature (hereinafter, T2) detected at the end of timing}, a gas leak is detected.

Therefore, when the gas is not used and there is no gas leakage, the gas volume V1 in the gas supply path at the start of the time measurement by the first time measurement means and the gas volume V2 at the end of the time measurement
(∵V1 = V2). Equation (1) is established based on Boyle-Charles law. (P1 · V1) / T1 = (P2 · V2) / T2 = K (K is a constant) (1) From the above, when gas is not used and there is no gas leakage, P1, T1, It can be derived that P2 and T2 have the relationship of the following equation (2). P1 / T1 = P2 / T1 (2) On the other hand, if gas leakage occurs, the gas volumes V1 and V2 become unequal (∵V1> V2), so that the relationship of equation (2) ′ can be derived. P1 / T1 ≠ P2 / T2 (2) ′

Focusing on the above equations (2) and (2) ', P
When 1 / T1 ≠ P2 / T2, by detecting gas leakage, gas leakage can be accurately detected without being affected by changes in gas temperature.

According to a second aspect of the present invention, as shown in the basic configuration diagram of FIG.
After the leak detection means has detected a gas leak, when the passing flow rate measuring means has measured a passing flow rate of a predetermined value or more,
The flow rate measuring device further comprises first leak point determining means 5a-5 for determining that a leak has occurred in the gas supply path downstream of the passing flow rate measuring means.

According to the second aspect of the present invention, when the passing flow rate measuring means detects a passing flow rate of, for example, 3 L / h (= predetermined value) or more after the leak detecting means detects the gas leak, the first leak is detected. The location determining means determines that a leak has occurred in the gas supply path downstream of the passing flow rate measuring means. Therefore, when the leak detecting means detects a gas leak by the first leak location determining means, the leak location can be specified.

According to a third aspect of the present invention, as shown in the basic configuration diagram of FIG.
A shutoff valve 20 for shutting off the gas supply to the combustor through the gas supply path by closing the valve, and a valve closing control means 5a for controlling the shutoff valve to be closed while the leak detecting means detects a gas leak. -6, a second timing means 5a-7 for starting timing of a second predetermined time during valve closing control of the shut-off valve by the valve closing control means, and a time detected by the second timing means at the time of starting the timing. A value obtained by dividing the gas pressure by the gas temperature detected at the start of the time measurement, and a gas pressure detected at the end of the time measurement by the second time measuring means; And a second leak point determining means 5a-8 for determining whether the leak point is upstream or downstream of the shut-off valve based on whether or not the value divided by the flow rate is equal to the flow rate. Exists in measuring equipment.

According to the third aspect of the invention, the valve closing control means closes the shut-off valve during the detection of the gas leak by the leak detecting means, and shuts off the gas supply through the gas supply path to the combustor. I do. The second timing means starts measuring a second predetermined time during the valve closing control of the shut-off valve by the valve closing control means. A value obtained by dividing the gas pressure detected by the second timing means at the start of timing by the gas temperature detected at the start of timing, and a gas pressure detected at the end of timing by the second timing means. Was detected at the end of timing,
It is determined whether the leak location is upstream or downstream of the shutoff valve based on whether or not the value divided by the gas temperature is equal. Therefore, when the leak detecting means detects a gas leak by the second leak location judging means, the leak location can be specified.

According to a fourth aspect of the present invention, there is provided the flow rate measuring device according to the first aspect, wherein a shutoff valve for shutting off gas supply to the combustor through the gas supply path by closing the valve.
The gas leak detection means detects a gas leak while detecting a gas leak, a valve closing control means for controlling the shutoff valve to close the valve, and the detected gas pressure during the valve closing control of the shutoff valve by the valve closing control means There is provided a flow rate measuring device comprising: a second leak point determining means for determining whether the leak point is upstream or downstream of the shutoff valve based on the change.

According to the fourth aspect of the present invention, the valve closing control means closes the shut-off valve during the detection of the gas leak by the leak detecting means, and supplies the gas through the gas supply path to the combustor. Cut off. The second leak point determining means determines whether the leak point is upstream or downstream of the shutoff valve based on the detected change in the gas pressure during the valve closing control. Therefore, when the leak detecting means detects a gas leak by the second leak location judging means, the leak location can be specified.

According to a fifth aspect of the present invention, as shown in the basic configuration diagram of FIG. 1, the flow rate measuring device according to the third or fourth aspect, wherein the leakage detecting means detects the gas leakage and then passes the gas. When the flow rate measuring means measures a passing flow rate equal to or more than a predetermined value, the flow rate measuring means further includes a first leak point detecting means 5a-4 for judging that a leak has occurred in a gas supply path downstream of the passing flow rate measuring means, The valve closing control means controls the shutoff valve to be closed when the leak detecting means is detecting gas leakage and the passing flow rate measuring means does not measure a passing flow rate equal to or more than the predetermined value. The flow rate measuring device is characterized in that:

According to the fifth aspect of the present invention, there is a limit to the measurement accuracy of the passing flow rate measuring means. For example, an extremely small passing flow rate smaller than a predetermined value cannot be measured. For this reason, when the passing flow rate detecting means does not measure the passing flow rate equal to or more than the predetermined value, the first leak point determining means determines whether a leak has occurred on the upstream side of the passing flow rate measuring means or on the downstream side. It is not possible to distinguish whether or not a leak of an ultra-small passage flow rate smaller than a predetermined value has occurred, and it is not possible to specify a leak location. On the other hand, the second leak location judging means can make the above distinction, but since the gas shutoff valve needs to be shut off, the combustor cannot be used immediately during shutoff.

Focusing on the above, the valve closing control means shuts off only when the leak detecting means is detecting gas leakage and the passing flow rate measuring means does not measure a passing flow rate equal to or more than a predetermined value. The valve is closed.

According to a sixth aspect of the present invention, there is provided the flow rate measuring apparatus according to any one of the first to fifth aspects, wherein the temperature detecting means includes a temperature for correcting a variation of the passing flow rate depending on the gas temperature. The flow rate measuring device is characterized in that the detecting means is diverted.

According to the sixth aspect of the present invention, the temperature detecting means for correcting the variation of the passing flow rate depending on the gas temperature is diverted as the temperature detecting means. There is no need to separately provide a temperature detecting means for detection.

According to a seventh aspect of the present invention, there is provided a use judging means 5a-2 for judging whether or not a combustor to which a gas is supplied through a gas supply passage 10 uses a gas; Temperature detecting means 15 for detecting gas temperature, and pressure detecting means 16 for detecting gas pressure in the gas supply path.
And the use judging means, while judging the absence, a first time measuring means 5a-3 for starting time measurement of a first predetermined time, and the gas pressure detected at the time start by the first time measuring means, A value obtained by dividing the gas temperature detected at the start of the time measurement and a value obtained by dividing the gas pressure detected at the end of the time measurement by the first time measuring means by the gas temperature detected at the end of the time measurement is obtained. When they are not equal to each other, there is provided a leak detecting device comprising a leak detecting means 5a-4 for detecting a gas leak.

According to the seventh aspect of the present invention, the first time counting means starts counting the first predetermined time while the use judging means judges that the answer is no. A value obtained by dividing the gas pressure (hereinafter, P1) detected at the start of timekeeping by the first timekeeping means by a gas temperature (hereinafter, T1) detected at the start of timekeeping, and the timekeeping by the first timekeeping means. When the value obtained by dividing the gas pressure (hereinafter, P2) detected at the end of the time measurement by the gas temperature (hereinafter, T2) detected at the end of the time measurement is not equal, a gas leak is detected. Therefore, when P1 / T1 ≠ P2 / T2, by detecting gas leakage, gas leakage can be accurately detected without being affected by a change in gas temperature.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a gas supply system constituted by a gas meter incorporating the flow rate measuring device of the present invention. The gas supply system includes, for example, an LP gas cylinder 80 that supplies a high-pressure gas, a regulator 82 that reduces the pressure of the high-pressure gas supplied from the LP gas cylinder 80 via the high-pressure piping unit 81, and a gas supply unit that supplies the gas supplied from the regulator 82. It comprises a gas meter 83 for measuring the flow rate and a combustor 84 for consuming gas.

FIG. 3 shows the gas meter 83 described above.
The illustrated gas meter is configured as a thermal type, and has a micro flow sensor 1 that is disposed in a gas supply path through which a gas flows and outputs a signal corresponding to the gas flow rate. As the micro flow sensor 1, a sensor capable of detecting a flow rate of 3 L / H or more is used.

The micro flow sensor 1 is disposed on an inner wall of a gas supply path 10 shown in a cross section in FIG. 4, and includes a semiconductor base 11 and a thin film layer (not shown) formed on the semiconductor base 11. A temperature sensor 12, such as a thermopile, which generates a thermoelectromotive force according to the temperature formed on the thin film layer;
13 and a heater resistor 14 for heating,
Temperature sensor 12, heater resistor 14, temperature sensor 13 from the upstream side in the flow direction D of the gas flowing in gas supply passage 10.
Are arranged at regular intervals along the flow direction D.
The micro flow sensor 1 also includes a temperature sensor 15 as temperature detecting means for measuring the temperature of the gas passing through the gas supply path 10.

The above-described heater resistor 14 is connected to the power supply 3 via the switch 2 as shown in FIG.
The power supply 3 has a battery 31 and a constant voltage circuit 33 as shown in FIG. 5, and is configured to output the voltage of the electric power from the battery 31 as a predetermined constant voltage by the constant voltage circuit 33. 2 turns on in response to the output of the control signal S1 from the microcomputer (hereinafter, μCOM) 5, and applies a predetermined constant voltage from the power supply 3 to the heater resistor 14. That is, the heater resistor 14
5 and is heated by a drive pulse output in response to the control signal S1 from the step S5. The power supply 3 includes various controls such as a constant current circuit, a constant heating temperature, and a constant temperature, in addition to the constant voltage control described above.

Further, when thermopiles are used as the temperature sensors 12 and 13, the thermoelectromotive forces are respectively non-inverted and amplified through non-inverting amplifiers 17 and 18 as shown in the equivalent circuit diagram of FIG. The differential amplifier 19 outputs a signal corresponding to the difference therebetween.

The principle of the micro flow sensor 1 having the above configuration will be described below. The heater resistor 14 has a μC
Electricity is applied by a drive pulse simultaneously with the output of the control signal S1 from the OM 5, and heating is performed for a predetermined time. As a result,
When the gas is not flowing through the gas supply path 10, heat is transmitted to the gas near the heater resistor 14,
The temperature distribution near the upstream and downstream sides is a symmetric distribution. That is, since the temperatures of the temperature sensors 12 and 13 rise to the same temperature, the thermoelectromotive forces of the temperature sensors 12 and 13 become almost equal, and the output from the differential amplifier 19 becomes almost zero.

Now, while the heater resistor 14 is energized,
When the gas flows in the gas flow direction D in FIG. 4, the upstream side is cooled and the temperature drops. On the other hand, on the downstream side, the heat conduction is promoted from the heater resistor 14 by using the gas flow as a medium, and the temperature rises. As a result, the temperature of the temperature sensor 12 on the upstream side of the heater resistor 14 is decreased by the gas, so that the thermoelectromotive force is reduced. On the other hand, the temperature of the temperature sensor 13 on the downstream side is increased by the gas, so that the thermoelectromotive force is increased. I do. When the flow velocity increases, the above-mentioned temperature drop and temperature rise also increase, so that the temperature sensor 1
The output from the differential amplifier 19, which is the difference between the thermoelectromotive forces 2 and 13, is an output corresponding to the flow velocity. The signal from the differential amplifier 19 of the micro flow sensor 1 corresponding to the flow rate of the gas is amplified by the amplifier 6 and then supplied to the μCOM 5.

The above-mentioned μCOM 5 is a central processing unit (CPU) 5a that performs various processes according to a program,
ROM 5b, which is a read-only memory storing a program for processing performed by the CPU 5a, a work area used in various processing steps in the CPU 5a, and a RAM 5c, which is a read / write memory having a data storage area for storing various data. And a signal obtained by amplifying the signal from the micro flow sensor 1 by the amplifier 6
An A / D converter 5d for digital conversion is built in, and these are interconnected by a bus line (not shown).

The gas meter further includes a gas supply path 10
A pressure sensor 16 as pressure detecting means for detecting the pressure of the gas inside, and a gas supply provided through the gas supply passage 10 to the combustor 84 when the valve is closed and provided upstream of the micro flow sensor 1 and the pressure sensor 16. And a shutoff valve 20 for shutting off. In addition, as a pressure sensor,
For example, a gas pressure of 10 Pa or less can be detected.

The CPU 5a in the .mu.COM 5 outputs the control signal S1 intermittently to energize the heater resistor 14 with a drive pulse, and converts the heater resistor 14 into an analog amplified signal from the amplifier 6 corresponding to the flow rate of the gas output by the energization. Based on this, a passing flow rate measurement process for measuring the passing flow rate of the gas flowing through the gas supply path 10 is performed.

The CPU 5a performs a use judging process for judging whether or not gas is used, based on the flow rate. Specifically, the CPU 5a determines that the measured flow rate is 2
When it is less than 1 L / h, it is determined that the gas is not used. The CPU 5a also performs a first clocking process for starting clocking of a predetermined time when it is determined to be no by the use determining process. The CPU 5a further performs a gas leak detection process for detecting a gas leak in the gas supply path 10 described later.

The details of the gas leak detection process will be described below. When the gas is not used and there is no gas leakage, the gas volume in the gas supply passage 10 which is about the same as the predetermined time does not change. That is, the gas volume V1 at the start of timekeeping by the first timekeeping process and the gas volume V2 at the end of timekeeping
(∵V1 = V2). Equation (1) is established based on Boyle-Charles law.

P1 · V1 / T1 = P2 · V2 / T2 = K (K is a constant) (1) where P1 is the gas pressure at the start of timekeeping, P2 is the gas pressure at the end of timekeeping, and T1 Indicates the gas temperature at the start of timekeeping, and T2 indicates the gas temperature at the end of timekeeping.

From the above, when the gas is not used,
When there is no gas leakage, it can be derived that P1, T1, P2 and T2 have the relationship of the following equation (2). P1 / T1 = P2 / T2 (2) On the other hand, if gas leaks, the gas volumes V1 and V2 become unequal (∵V1> V2), so that the relationship of equation (2) ′ can be derived. P1 / T1 ≠ P2 / T2 (2) ′

Therefore, paying attention to equations (2) and (2) ′, in the gas leak detection processing, P1 / T1 ≠ P2 / T
When 2, the gas leak is detected. As described above, by detecting the gas leak using (2) and (2) 'including the gas temperature, the gas leak can be accurately detected without being affected by the gas temperature change.

In addition to the above-described processing, the CPU 5a integrates the flow rate obtained by the flow rate measurement processing to obtain an integrated flow rate, and displays the integrated flow rate value obtained by the flow integration processing on the display unit 7. An integrated value display process to be performed, and an alarm display process for displaying an alarm indicating the fact on the display unit 7 when a gas leak is detected are performed.

The detailed operation of the gas meter incorporating the above-described flow rate measuring device will be described below with reference to the flowchart of FIG. 6 showing the processing procedure of the CPU 5a. First, the CPU 5a starts the operation by turning on the battery power, for example, and in an initial step (not shown), the μCOM5
After initializing various areas formed in the RAM 5c, the process proceeds to the first step S1.

First, the CPU 5a functions as a passing flow rate measuring means, fetches a signal corresponding to the flow rate output from the amplifier 6, and performs a passing flow rate measuring process for measuring the passing flow rate of the gas from the fetched signal (step S1). ). Thereafter, based on the gas temperature detected by the temperature sensor 15, the CPU 5a performs a correction process for correcting a change in the measured passing flow rate that varies depending on the gas temperature (Step S).
2).

Next, the CPU 5a functions as a use determining means, and determines whether the gas is being used by the combustor 84 based on the flow rate corrected by the correction processing (step S3). Specifically, the passing flow rate is 21 L
/ H or more, the passing flow rate is 21 L / H
If so, it is determined that gas is being used (Y in step S3), and the process proceeds to steps S4 and S5.

In the following steps S4 and S5, the CPU
5a performs a passing flow rate integrating process for integrating the passing flow rate, and performs an integrated ground surface time process for displaying the integrated value on the display 7. On the other hand, if the passing flow rate is less than 21 L / H, it is determined that the gas is not used, and step S6 to be described later is performed.
To the leak detection process.

Hereinafter, the details of the leak detection processing will be described with reference to the flowcharts of FIG. 7 and FIG. First, the CPU 5a operates the temperature sensor 1
5 and the gas pressure detected by the pressure sensor 16 are stored in the previous temperature area T1 and the previous pressure area P1 formed in the RAM 5c (step S61). Next, the CPU 5a functions as a first timing unit,
The clocking area t1 formed in c is incremented (step S62), and clocking for a predetermined time is started.

Thereafter, the CPU 5a functions as a leak detecting means, and the time count area t1 becomes a predetermined time (step S5).
63) If it is determined that a predetermined time has elapsed since the start of the timing, the gas temperature and the gas pressure detected by the temperature sensor 15 and the pressure sensor 16 are formed in the RAM 5c after the temperature area T1 and the rear pressure area P2. (Step S64). By the above steps S61 to S64,
Front and rear temperature areas T1, T2 and front and rear pressure areas P1, P
2 stores the gas temperature and the gas pressure detected before and after the predetermined time phase, respectively.

Thereafter, the CPU 5a determines that P1 / T1 = P2
/ T2 (Expression (2)) is determined (step S65). Then, if the above equation (2) is satisfied (Y in step S65), the CPU 5a determines that gas leakage has not occurred, and returns. On the other hand, if the above equation (2) is not satisfied, it is determined that a gas leak has occurred, and a warning display process for displaying a warning to that effect on the display 7 is performed (step S66).

The gas flow rate Qi is used as a first leak location judging means for identifying a gas leak location.
Is measured again, and it is determined whether the measured passing flow rate Qi is 3 L / H or more (step S67). If the measured flow rate Qi is 3 L / H or more (step S6
7) Y, the micro flow sensor 1, that is, the gas meter 8
It is determined that there is a gas leak point in the gas supply path 10 downstream of 3 and the display notifying the fact is displayed on the display 7 (step S68).

On the other hand, if the gas flow rate Qi is less than 3 L / H (Y in step S67), the gas meter 83
Gas leakage at the more upstream side or 3L /
In order to identify whether an extremely small amount of gas leakage less than H has occurred downstream of the gas meter 83, step S69 in FIG.
Proceed to.

In step S69 of FIG.
“a” functions as a valve closing control unit, and outputs a valve closing control signal to the shutoff valve 20 to perform a valve closing control process for closing the shutoff valve 20. After that, the same operation as in steps S61 to S65 is performed, and it is determined again whether or not gas leakage has occurred. As described above, by closing the shut-off valve 20 upstream of the temperature sensor 15 and the pressure sensor 16, it is determined whether or not gas leakage has occurred at the downstream of the shut-off valve 20, that is, the gas meter 83. can do.

Then, the CPU 5a determines in step S of FIG.
If P1 / T1 = P2 / T2 is not satisfied in the determination at 65 (N in step S65 of FIG. 8), the gas meter 83
It is determined that gas leakage has occurred on the further downstream side, and the fact is displayed on the display 7 (step S71). on the other hand,
When P1 / T1 = P2 / T2 holds (Y in step S65 in FIG. 8), it is determined that gas leakage has occurred on the upstream side, and the fact is displayed on the display 7 (step S65).
70).

As is clear from the operation of the CPU 5a described with reference to the flowchart of FIG.
It can be seen that “a” functions as a second clock unit and a second leak determination unit.

As described above, in addition to the presence or absence of gas leakage,
By specifying the leak location and displaying it on the display 7, the gas company employee can easily and quickly check the gas leak location.

After detecting the gas leakage, the above-mentioned flow rate measuring device determines in step S67 of FIG.
When i cannot measure 3 L / H or more, the shut-off valve 20 is shut off for the first time to identify a gas leak location. By doing so, the flow rate measuring device of the present invention, when the location of the gas leak can be specified based on the passing flow rate, the shut-off valve 2
0 is not shut off, and the shutoff valve 20 is not inadvertently closed.

Further, the above-mentioned flow rate measuring device also serves as a temperature sensor for correction and a temperature sensor for detecting gas leakage. In this way, by also using the temperature sensors separately, it is not necessary to separately provide a temperature sensor, and the cost can be reduced.

In the above-described embodiment, after the gas leak is detected, the flow rate Qi is determined in step S67 in FIG.
Is not more than 3 L / H, the shut-off valve 20 is shut off, and it is determined again whether or not a gas leak has occurred downstream of the gas meter using the equation (2). However, for example, as described above, the pressure sensor 16 is highly accurate (1
If the pressure drop is lower than 0 Pa), the pressure drop is determined after the shutoff valve 20 is shut off. If there is a pressure drop, the downstream leak is determined. Is also good.

However, in the method of determining a gas leak location based only on the gas pressure as described above, there are cases where the gas leak location cannot be accurately determined due to the influence of the temperature change as described above. For this reason, it is better to determine the gas leak location using the equation (2) again as in the above embodiment.

Further, in the above-described embodiment, the gas leak location is determined based on the flow rate Qi after the gas leak is detected. ) Alternatively, the gas leak location may be determined based on the pressure change. However, in this case, since the shut-off valve 20 is shut off, there is a disadvantage that if the gas is used by the consumer at this time, the gas cannot be used immediately. For this reason, as in the above-described embodiment, it is preferable to make a cut-off determination when the determination cannot be made only by the passing flow rate Qi.

[0058]

As described above, according to the first and seventh aspects of the present invention, it is possible to accurately detect a gas leak without being affected by a change in gas temperature, thereby improving the accuracy of leak detection. Thus, it is possible to obtain a flow measurement device and a leakage detection device that achieve the above.

According to the second, third and fourth aspects of the present invention,
When the leak detecting means detects a gas leak by the first leak location determining means, the leak location can be specified, so that the gas leak location can be easily and quickly confirmed. Can be obtained.

According to the fifth aspect of the present invention, when the leak detection means is detecting gas leakage by the valve closing control means and the passing flow rate measuring means does not measure the passing flow rate equal to or more than a predetermined value. Only the shutoff valve is closed, so that a flow measurement device in which the gas shutoff valve is not closed unnecessarily can be obtained.

According to the sixth aspect of the present invention, there is no need to separately provide a temperature detecting means for correction and a temperature detecting means for detecting gas leakage, so that it is possible to obtain a flow rate measuring device which reduces costs. Can be.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a flow measurement device incorporating a leak detection device of the present invention.

FIG. 2 is a diagram showing a gas supply system.

FIG. 3 is a diagram showing an embodiment of a gas meter incorporating the flow rate measuring device and the leak detecting device of the present invention.

FIG. 4 is a diagram showing details of the micro flow sensor of FIG. 3;

FIG. 5 is a circuit diagram showing details of the micro flow sensor of FIG. 3;

FIG. 6 is a flowchart showing a processing procedure of a CPU constituting the gas meter of FIG. 3;

FIG. 7 is a flowchart showing a processing procedure of a CPU for a leak detection process shown in FIG. 6;

FIG. 8 is a flowchart showing a processing procedure of a CPU for a leak detection process shown in FIG. 6;

[Explanation of symbols]

 5a-1 Passing flow rate measuring means (CPU) 5a-2 Usage determining means (CPU) 5a-3 First time measuring means (CPU) 5a-4 Leak detecting means (CPU) 5a-5 First leaking point determining means (CPU) 5a-6 Valve closing control means (CPU) 5a-7 Second time measuring means (CPU) 5a-8 Second leak location judging means (CPU) 10 Gas supply path 15 Temperature detecting means (temperature sensor) 16 Pressure detecting means (pressure) Sensor) 20 shut-off valve 84 combustor

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kazumitsu Atsui 9-10 Misonodai, Fujisawa-shi, Kanagawa Japan Applied Flow Co., Ltd. F-term (reference) 2F030 CA10 CB02 CC13 CD15 CE02 CE25 CE27 CF05 CF11 CF20 2F035 EA02 EA05 EA08 2G067 AA14 CC04 DD02 DD04 DD08

Claims (7)

[Claims] 1. A flow rate measuring device provided in a gas supply path and comprising a flow rate measuring means for measuring a flow rate of a gas supplied to a combustor through the gas supply path, wherein the combustor includes the gas Use determination means for determining whether or not the gas supply path is used; temperature detection means for detecting a gas temperature in the gas supply path; pressure detection means for detecting a gas pressure in the gas supply path; Means, while determining whether or not, the first timing means to start the timing of the first predetermined time, and the gas pressure detected at the start of the timing by the first timing means, was detected at the start of the timing, A gas leak is detected when the value divided by the gas temperature is not equal to the gas pressure detected at the end of the timing by the first timing means, and the gas pressure detected at the end of the timing is divided by the gas temperature. Do Flow rate measuring apparatus characterized by comprising a motor detecting means. 2. The flow rate measuring device according to claim 1, wherein after the leak detecting means detects a gas leak, the passing flow rate measuring means measures a passing flow rate equal to or more than a predetermined value.
A flow rate measuring device comprising: a first leak point determining means for determining that a leak has occurred in a gas supply path downstream of the passing flow rate measuring means. 3. The flow measuring device according to claim 1, wherein the shutoff valve shuts off a gas supply to the combustor through the gas supply path by closing the valve, and the leak detecting means is detecting a gas leak. A valve closing control unit that controls the shutoff valve to be closed; a second timing unit that starts measuring a second predetermined time during the valve closing control of the shutoff valve by the valve closing control unit; 2 The gas pressure detected at the start of the timing by the timing means, the gas pressure detected at the start of the timing, a value divided by the gas temperature, and the gas pressure detected at the end of the timing by the second timing means, A second leak point determining unit that determines whether the leak point is upstream or downstream of the shutoff valve based on whether or not the value detected at the end of the timing is equal to the value divided by the gas temperature. Flow rate characterized by Measuring apparatus. 4. The flow rate measuring device according to claim 1, wherein a shutoff valve for shutting off a gas supply to the combustor through the gas supply path by closing the valve, and the gas leak detecting means detects a gas leak. During the valve closing control of the shut-off valve by the valve-closing control means, based on a detected change in gas pressure, the leak location is determined by the shut-off valve. A flow rate measuring device comprising: a second leak point judging means for judging whether it is more upstream or downstream. 5. The flow rate measuring device according to claim 3, wherein, after the leak detecting means detects a gas leak, the passing flow rate measuring means measures a passing flow rate equal to or more than a predetermined value.
The apparatus further comprises first leak point detecting means for determining that a leak has occurred in a gas supply path downstream of the passing flow rate measuring means, wherein the valve closing control means is detecting a gas leak by the leak detecting means. The flow rate measuring device, wherein the flow rate measuring device controls the shutoff valve to be closed when the flow rate measuring means does not measure the flow rate equal to or more than the predetermined value. 6. The flow rate measuring device according to claim 1, wherein a temperature detecting means for correcting a variation of the passing flow rate depending on the gas temperature is used as the temperature detecting means. A flow measuring device characterized by the above-mentioned. 7. A use judging means for judging whether or not a combustor to which gas is supplied through a gas supply path uses gas, a temperature detection means for detecting a gas temperature in the gas supply path, Pressure detecting means for detecting a gas pressure in the gas supply path, first time measuring means for starting time measurement of a first predetermined time while the use judging means judges no, and the first time measuring means The gas pressure detected at the start of timing, the value obtained by dividing the gas temperature detected at the start of timing, and the gas pressure detected at the end of timing by the first timing means are detected at the end of timing. A leak detecting means for detecting a gas leak when the value divided by the gas temperature is not equal.