JP5399293B2 - Micro leak judgment device and micro leak judgment method - Google Patents

Description

  The present invention relates to a minute leak determination device and a minute leak determination method.

  Conventionally, in determining a minute leak, for example, a long-term flow rate such as 1 hour is measured, and the flow rate value (the number of flow pulses in the case of a membrane gas meter) during the measurement period is less than a specified value. Accordingly, it is determined whether or not a slight leak has occurred (see, for example, Patent Document 1).

JP 2004-132809 A

  Here, some gas appliances are accompanied by a fire, such as a gas stove, a gas table, and a table stove. Such melting fire has a low flow rate and tends to be performed over a long period of time, and there is a possibility of misjudging the flow rate due to this burning fire as the flow rate due to slight leakage.

  The present invention has been made in order to solve such a conventional problem, and an object of the present invention is to provide a microleakage determination apparatus and a microleakage determination capable of improving the determination accuracy of microleakage. It is to provide a method.

  The micro leak judgment device of the present invention is a micro leak judgment device that judges micro gas leak, and when the micro flow rate is detected within a predetermined time after the flow rate exceeding the micro flow rate is detected, the micro flow rate is determined. It is provided with a fire determining means for determining whether the flow rate is due to a smoldering fire, and a micro leak determining means for determining whether the micro flow rate is a flow rate due to a micro leak. When the flow rate is determined, the minute flow rate is not determined to be due to a slight leakage.

  According to this minute leakage judgment device, a minute flow rate is detected within a predetermined time after a flow rate exceeding a minute flow rate (for example, a flow rate of at least 50 L / h, preferably 100 L / h or more) is detected. In this case, it is determined that the minute flow rate is the flow rate due to the fire. Here, in a gas appliance (for example, a gas stove or a gas table) that accompanies a torch, first, a large flow rate flows at the time of ignition, and then a slight flow rate tends to flow by adjusting the heating power to become a torch. In this way, the flow rate of the gas appliance accompanied with a hot flash shows the above transition. For this reason, when this flow rate transition is obtained, it can be inferred that the minute flow rate is not due to minute leakage but due to hot fire. Therefore, when such a flow rate transition is observed, it is possible to improve the determination accuracy of the minute leak by determining that the minute flow rate is not due to the minute leak.

  Further, in the microleakage determination device of the present invention, the apparatus further comprises a gas appliance judging means for judging whether or not a gas appliance accompanied by a hot fire is used, and the hot fire judging means is a gas appliance accompanied by a hot fire by the gas appliance judging means. It is preferable to determine that the minute flow rate is the flow rate due to the fire.

  According to this minute leak determination device, it is determined whether or not a gas appliance with a torch is used. If it is determined that a gas appliance with a torch is used, it is determined that the minute flow rate is due to a torch. For this reason, when it is determined that a gas appliance with a torch is used, the possibility that a slight leakage has occurred can be denied. Therefore, it is possible to further improve the accuracy of determining a minute leak.

  In the microleakage determination device according to the present invention, the gas appliance determination means may be a gas appliance with a flashing fire based on a waveform measured during a minute time from a change of at least one of the flow rate and the pressure more than a predetermined value. It is preferable to determine whether or not it has been used.

  According to this minute leak determination device, it is determined whether or not a gas appliance accompanied by a hot fire has been used based on a waveform measured during a minute time since a predetermined change in at least one of the flow rate and pressure. Here, when the gas appliance starts to be used, it tends to show a waveform specific to the gas appliance in a minute time immediately after the start (for example, 2 seconds at the maximum). For this reason, it is possible to determine a gas appliance accompanied by a hot fire in a short time by judging a gas appliance accompanied by a hot fire based on the waveform in this minute time.

  Further, in the microleakage determination device of the present invention, when a trigger signal is generated by a trigger signal generating means for generating a trigger signal when at least one of the flow rate and the pressure changes more than a predetermined value, the trigger signal is generated by the trigger signal generating means. And a sampling time adjusting means for shortening at least one of the sampling times of the pressure by a minute time from a predetermined normal sampling time.

  According to this minute leakage judgment device, a trigger signal is generated when at least one of the flow rate and pressure changes more than a predetermined value, and when the trigger signal is generated, the sampling time of at least one of the flow rate and pressure is set to a minute time. Shorten. For this reason, when acquiring the waveform in a minute time, it is possible to prevent the waveform from leaking.

  Further, in the microleakage determination apparatus of the present invention, the sampling time adjusting means sets the sampling time of at least one of the flow rate and the pressure to be higher than the normal sampling time until a trigger signal is generated by the trigger signal generating means. It is preferable to keep it long.

  According to this minute leak determination device, the sampling time of at least one of the flow rate and the pressure is set longer than the normal sampling time until the trigger signal is generated. Here, the case where no trigger signal is generated and the flow rate or pressure does not change more than a predetermined amount can be said to be a case where the flow rate or pressure is stable and the necessity for measurement is small. Therefore, in such a case, power consumption can be reduced by increasing the sampling time.

  Further, in the micro leak determination device of the present invention, when the low flow determination unit determines that the small flow rate is a flow rate due to hot fire, the micro leak determination unit further includes a storage unit that stores a flow rate value due to the hot fire, When the flow rate value by the fire and the flow value within the specified range stored in the storage means are detected, it is preferable to determine the flow rate within the specified range as the flow rate by the hot fire.

  According to this minute leakage judgment device, when it is determined that the minute flow rate is a flow rate due to hot fire, the flow rate value due to the hot fire is stored, and when the stored flow rate value and the flow rate value within a specified range are detected, The flow rate within the specified range is determined to be the flow rate due to fire. As described above, since the flow rate value of the torch is stored, it is possible to further improve the accuracy of determination of minute leakage.

  Further, the micro leak judgment method of the present invention is a micro leak judgment method for judging the micro leak of gas, and when the micro flow rate is detected within a predetermined time after the flow rate exceeding the micro flow rate is detected, It is provided with a flame determination step for determining whether the flow rate is a flow rate due to a flash fire, and a micro leak determination step for determining whether the micro flow rate is a flow rate due to a micro leak, and in the micro leak determination step, When it is determined that the flow rate is due to hot water, the minute flow rate is not determined to be due to minute leakage.

  According to this minute leakage determination method, if the minute flow rate is detected within a predetermined time after the flow rate exceeding the minute flow rate is detected, it is determined that the minute flow rate is a flow rate due to fire. Here, in a gas appliance (for example, a gas stove or a gas table) that accompanies a torch, first, a large flow rate flows at the time of ignition, and then a slight flow rate tends to flow by adjusting the heating power to become a torch. In this way, the flow rate of the gas appliance accompanied with a hot flash shows the above transition. For this reason, when this flow rate transition is obtained, it can be inferred that the minute flow rate is not due to minute leakage but due to hot fire. Therefore, when such a flow rate transition is observed, it is possible to improve the determination accuracy of the minute leak by determining that the minute flow rate is not due to the minute leak.

  According to the present invention, it is possible to provide a micro leak determination device and a micro leak determination method capable of improving the micro leak determination accuracy.

It is a lineblock diagram of the gas supply system containing the minute leak judgment device concerning the embodiment of the present invention. It is a block diagram which shows the detail of the gas meter shown in FIG. It is a figure which shows an example of the flow volume waveform of the gas appliance with a hot fire. It is a figure which shows the outline of the gas leak vibration waveform produced | generated by the production | generation part shown in FIG. It is a figure which shows the pressure change at the time of gas leak. It is a graph which shows continuous NCC at the time of gas leak. It is a graph which shows the pressure change at the time of gas appliance use start, Comprising: (a) shows the pressure change at the time of gas table use start, (b) shows the pressure change at the time of a small water heater use start, (c) Indicates the pressure change at the start of use of the water heater. It is a graph which shows the continuous NCC calculated by the gas leak / gas appliance judgment part shown in FIG. 2, (a) shows continuous NCC at the time of gas table use start, (b) starts use of a small water heater The continuous NCC at the time is shown, and (c) shows the continuous NCC at the start of use of the water heater. It is a graph which shows the spectrum data obtained by Fourier-transforming the pressure waveform when a gas leak generate | occur | produces. It is a graph which shows the spectrum data obtained by Fourier-transforming the pressure waveform when a gas table is used. It is a graph which shows the spectrum data obtained by Fourier-transforming the pressure waveform when a gas BF bath is used. It is a flowchart which shows an example of the microleakage determination method which concerns on this embodiment. It is a basic flowchart of gas leak / gas appliance judgment. FIG. 14 is a first flowchart showing details of the gas leak / gas appliance determination shown in step S14 of FIG. 13 and shows the first method. FIG. 14 is a second flowchart showing details of the gas leak / gas appliance determination shown in step S14 of FIG. 13 and shows the second method.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a gas supply system including a microleakage determination apparatus according to an embodiment of the present invention. The gas supply system 1 supplies fuel gas to each gas appliance 10 such as a gas stove, a fan heater, a water heater, a floor heater, a gas table, and a gas BF bath. Here, the gas table is the gas appliance 10 accompanied by a fire. Toro-fire is the minimum area of fire with low momentum, and sometimes referred to as lukewarm or simmering fire. Specifically, in the case of table stoves, it refers to the amount of fire when boiling boiled beans or porridge for a long time. In addition, the gas appliance 10 accompanied with a torch is not limited to a gas table, or there are other types such as a gas stove and a table stove.

  Such a gas supply system 1 includes a plurality of gas appliances 10, a gas supply source regulator 20, pipes 31 and 32, and a gas meter (micro-leakage determination device) 40. In the example illustrated in FIG. 1, the gas meter 40 is described as an example of the minute leak determination device, but the minute leak determination device is not limited to the gas meter 40.

  The adjuster 20 adjusts the fuel gas from the upstream to a predetermined pressure and flows it through the first pipe 31. The first pipe 31 connects the regulator 20 and the gas meter 40. The second pipe 32 is a pipe that connects the gas meter 40 and the gas appliance 10. The gas meter 40 measures the flow rate of the fuel gas and displays the integrated flow rate. In such a gas supply system 1, a flow path connected to the first pipe 31 and the second pipe 32 is formed in the gas meter 40, and the fuel gas flowing through the regulator 20 flows from the first pipe 31 to the gas meter 40, And the gas appliance 10 is reached through the second pipe 32 and burned in the gas appliance 10.

  FIG. 2 is a configuration diagram showing details of the gas meter 40 shown in FIG. As shown in FIG. 2, the gas meter 40 has a function of determining minute gas leakage. The gas meter 40 includes a flow sensor 41, a pressure sensor 42, a determination unit 43, a trigger signal generation unit 44, a generation unit 45, a similarity transition storage unit 46, a spectrum data storage unit 47, and a flow rate value storage. Part (storage means) 48. Among these configurations, the determination unit 43, the generation unit 45, the similarity transition storage unit 46, the spectrum data storage unit 47, and the flow rate value storage unit 48 can be configured by a microcomputer.

  The flow sensor 41 outputs a measurement value signal corresponding to the gas flow rate in the flow path of the gas meter 40, and is constituted by an ultrasonic sensor, a flow sensor, or the like. The pressure sensor 42 outputs a signal of a measurement value corresponding to the gas pressure in the flow path of the gas meter 40, and is configured by a sensor such as a piezoresistive type or a capacitance type.

  The determination unit 43 performs various determinations in the gas meter 40. For example, the determination unit 43 determines gas leakage and the gas appliance 10 to be used based on a signal from the flow sensor 41 and a signal from the pressure sensor 42. Such a determination unit 43 includes a hot water determination unit (fire fire determination unit) 43a, a slight leak determination unit (micro leak determination unit) 43b, a gas leak / gas appliance determination unit (gas appliance determination unit) 43c, and a sampling time. An adjustment unit (sampling time adjustment means) 43d is provided.

  The hot water judgment part 43a judges the flow rate by hot water. Specifically, the hot fire determination unit 43a determines the flow rate of hot fire based on the flow rate transition shown in FIG.

  FIG. 3 is a diagram illustrating an example of a flow rate waveform of the gas appliance 10 accompanied by a fire. As shown in FIG. 3, first, it is assumed that the gas appliance 10 accompanied by a torch is started to be used at time t1. At this time, since the ignition is initially performed, a flow rate exceeding a minute flow rate flows, and the flow rate value indicates F2.

  Thereafter, the user gradually rotates the rotary knob in the gas table so that the user can turn off the heating power of the gas appliance 10. Thereby, the flow rate gradually decreases from time t2 to time t3, and the minute flow rate F1 is shown at time t3. In most cases, the time from the ignition at time t1 to the melting at time t3 is within several tens of minutes (an example of a predetermined time).

  Next, from time t3 to time t4, stew by boiling is performed, and then use of the gas appliance 10 accompanied by boiling is finished. Thereby, the gas appliance 10 shifts from the melted fire state to the fire extinguisher state, and the flow rate value becomes 0 L / h.

  Thus, at the time of use of the gas appliance 10 accompanied by hot fire, the minute flow F1 will flow after the flow F2 exceeding the minute flow F1. Moreover, the time from the flow of the flow rate F2 (time t1) to the minute flow rate F1 (time t2) is within a predetermined time.

  Reference is again made to FIG. The hot water judgment unit 43a captures the flow rate transition as shown in FIG. That is, when the flow rate F1 exceeding the minute flow rate F1 is detected and the minute flow rate F1 is detected within a predetermined time after the flow rate F2 is detected, the torch fire determination unit 43a determines that the minute flow rate F1 is a flow rate due to the fire.

  The minute leakage determination unit 43b determines whether the minute flow rate F1 is a flow rate due to minute leakage. The minute leak determination unit 43b determines that the minute flow rate F1 is not a flow rate due to minute leakage when the flow rate due to the fire is determined by the torch determination unit 43a. That is, the minute leakage determination unit 43b determines that the minute flow rate F1 is not due to minute leakage when the flow rate transition as shown in FIG. 3 is observed and it can be inferred that the gas appliance 10 accompanied by hot water is used. Will be.

  The gas leak / gas appliance determination unit 43c determines whether or not a gas leak has occurred and determines the gas appliance 10 that has been used. In particular, the gas leak / gas appliance determination unit 43c determines whether or not the gas appliance 10 accompanied by a fire is used. Based on this determination, the minute leakage determination unit 43b further distinguishes between the minute leakage and the flow rate due to hot water.

  In detail, the gas leakage / gas appliance determination unit 43c determines gas leakage (excluding minute leakage) in cooperation with the generation unit 45 and the similarity transition storage unit 46, and can determine that no gas leakage has occurred. In this case, the gas appliance 10 in use is determined (first method). Further, the gas leak / gas appliance determination unit 43c determines that a gas leak (excluding a slight leak) is determined in cooperation with the spectrum data storage unit 47, and is in use when it can be determined that no gas leak has occurred. The gas appliance 10 is determined (second method). In any method, the gas leak / gas appliance determination unit 43c is based on a waveform measured during a minute time (up to 2 seconds) from a predetermined change in at least one of the gas flow rate and the gas pressure. Gas leakage and the gas appliance 10 to be used will be judged.

  First, the first method will be described. The generation unit 45 generates a gas leak vibration waveform when it is assumed that a gas leak has occurred. The gas leakage / gas appliance determination unit 43c determines the gas leakage based on the gas leakage vibration waveform generated by the generation unit 45.

  FIG. 4 is a diagram showing an outline of a gas leakage vibration waveform generated by the generation unit 45 shown in FIG. As shown in FIG. 4, the generation unit 45 generates a gas leak vibration waveform that vibrates while the pressure decreases as time passes. This gas leakage vibration waveform is a waveform generated based on a second-order delay step response equation including the frequency, gain, and damping ratio of the damped vibration. Here, the present inventors have found that vibration occurs in the measured values of the pressure and the flow rate in a minute time (maximum 2 seconds) immediately after the occurrence of gas leakage. Therefore, the generation unit 45 generates a gas leakage vibration waveform based on a second-order lag step response formula as information necessary for the gas leakage determination, and the gas leakage / gas appliance determination unit 43c generates the generation unit 45. The occurrence of a gas leak is determined based on the gas leak vibration waveform generated in step (b).

  As shown in FIG. 4, the generation unit 45 generates a gas leakage vibration waveform of pressure. However, the generation unit 45 is not limited to this, and may generate a gas leakage vibration waveform that vibrates while the flow rate increases with time. Good. Further, it is desirable that this waveform is also determined based on a second-order delay step response equation.

Reference is again made to FIG. The gas leak / gas appliance determination unit 43 c calculates the transition of the similarity between the input signal waveform from the sensors 41 and 42 in the minute time and the gas leak vibration waveform generated by the generation unit 45. The similarity transition refers to continuous normal cross correlation (NCC) in the present embodiment. More specifically, the similarity _RNCC is obtained by the following equation (1). Gas leakage / gas appliance determination unit 43c, by performing the calculation of the similarity _{R NCC} according to the equation (1) continuously, the similarity transition (hereinafter, referred to as continuous NCC) Request.

  The gas leakage / gas appliance determination unit 43c determines the occurrence of gas leakage based on the calculated similarity transition. In particular, in this embodiment, as an example, it is determined that a gas leak has occurred when the representative value of the similarity transition calculated by the gas leak / gas appliance determination unit 43c is equal to or greater than a threshold value. Here, the representative value may be the total degree of similarity or the average value of a specific period of the whole degree of similarity, or the degree of similarity at a specific time after a change in pressure or flow rate occurs. Alternatively, other values may be used.

  Next, a pressure change at the time of gas leakage will be described with reference to FIG. FIG. 5 is a diagram showing a pressure change at the time of gas leakage. As shown in FIG. 5, when a gas leak occurs, a waveform that vibrates while the pressure decreases is shown. This waveform has a high correlation with the gas leak vibration waveform generated by the generation unit 45 as shown in FIG. For this reason, the representative value of the similarity transition shows a high value, and the gas leak / gas appliance determination unit 43c determines that a gas leak has occurred.

  FIG. 6 is a graph showing continuous NCC at the time of gas leakage. In FIG. 6, the solid line and the broken line indicate continuous NCC when conditions such as a difference in piping state, a difference in gas leak location, and a difference in gas leak flow rate in each home are different.

  As shown in FIG. 6, the continuous NCC immediately after the occurrence of a pressure change at the time of gas leakage (near time 0 seconds) shows a value of about “0.7” to “0.8”. However, the continuous NCC shows a value of “0.9” or more after time 0.025 seconds. Therefore, the gas leak / gas appliance determination unit 43c generates a gas leak when the representative value of the similarity transition calculated by the similarity transition gas leak / gas appliance determination unit 43c is “0.9” or more. Judge that

  On the other hand, as shown in FIG. 7, when the gas appliance is used, a vibration waveform different from that at the time of gas leakage is shown. FIG. 7 is a graph showing the pressure change at the start of gas appliance use, where (a) shows the pressure change at the start of use of the gas table, and (b) shows the pressure change at the start of use of the small water heater. (C) has shown the pressure change at the time of a water heater start use.

  As shown in FIG. 7A, a pressure waveform that smoothly vibrates at a pressure of about 2.9 kPa is obtained at the start of use of the gas table. In addition, as shown in FIG. 7B, a pressure waveform is obtained in which the pressure vibrates strongly by 0.1 kPa with reference to 2.93 kPa at the end of use of the small water heater. Furthermore, as shown in FIG.7 (c), the pressure waveform which shows a vibration a little rougher than a small water heater on the basis of a pressure of 2.93kPa is obtained at the time of use end of a water heater.

  FIG. 8 is a graph showing the continuous NCC calculated by the gas leak / gas appliance determination unit 43c shown in FIG. 2, wherein (a) shows the continuous NCC at the start of use of the gas table, and (b) is a small size. The continuous NCC at the start of use of the water heater is shown, and (c) shows the continuous NCC at the start of use of the water heater.

  When the use of the gas table is started, the vibration waveform of FIG. 7A is obtained, and the continuous NCC calculated by the gas leakage / gas appliance determination unit 43c is as shown in FIG. 8A. That is, the continuous NCC initially shows about “1.0”, then falls below “0.2”, and returns to “0.95” in about 0.04 seconds. The continuous NCC becomes about “0.5” in about 0.1 second, and then slowly rises to near “0.65”.

  When the use of the small water heater is started, the vibration waveform of FIG. 7B is obtained, and the continuous NCC calculated by the gas leak / gas appliance determination unit 43c is as shown in FIG. 8B. . That is, the continuous NCC initially shows about “1.0”, then falls below “0.2”, and returns to “0.9” in about 0.04 seconds. Then, the continuous NCC again decreases to about “0.4”, and then slowly increases to near “0.7”.

  Further, when the use of the water heater starts, the vibration waveform of FIG. 7C is obtained, and the continuous NCC calculated by the gas leak / gas appliance determination unit 43c is as shown in FIG. 8C. That is, the continuous NCC initially shows a value of “0.8”, then falls below “0.2” and returns to “0.7” in about 0.02 seconds. Then, the continuous NCC decreases to about “0.6” and then returns to about “0.7”. After that, the continuous NCC again decreases to about “0.5”, and then becomes less than “0.6” in about 0.1 second. Thereafter, the continuous NCC rises slowly to near “0.65”.

  Thus, at the start of use of the gas appliance 10, the continuous NCC does not show “0.9” or more in most periods. For this reason, the gas leak / gas appliance determination unit 43c determines that the gas appliance 10 has been used when the representative value of the continuous NCC is not equal to or greater than the threshold value.

  The continuous NCC is different for each gas appliance 10. For this reason, the gas leak / gas appliance determination unit 43c determines the gas appliance 10 used from such a continuous NCC pattern. Specifically, the continuous NCC pattern of each gas appliance 10 is stored in the similarity transition storage unit 46 shown in FIG. That is, the similarity transition storage unit 46 stores the continuous NCC pattern as shown in FIG. 8A for the gas table, and the continuous NCC pattern as shown in FIG. 8B for the small water heater. And a continuous NCC pattern as shown in FIG. 8C is stored for the water heater. Then, the gas leak / gas appliance determination unit 43c determines that the gas appliance 10 indicated by the continuous NCC data closest to the calculated continuous NCC among the continuous NCC data stored in the similarity transition storage unit 46 has been used. . In particular, when the gas appliance 10 indicated by the nearest continuous NCC data is a gas table, the gas leak / gas appliance determination unit 43c determines that the gas appliance 10 accompanied by a flash fire has been used.

  5 to 8 show the pressure vibration waveform and the continuous NCC based on the pressure vibration waveform, the gas leak determination can be similarly performed for the flow rate. In the following description, gas leak judgment based on the vibration waveform of pressure will be described, but it goes without saying that the same applies to the flow rate.

  Next, details of the gas leakage vibration waveform will be described. If it demonstrates in detail, the production | generation part 45 will produce | generate a gas leak vibration waveform as follows. First, the generation unit 45 stores the following expression (2).

Here, y (t) indicates the amount of change in pressure, K indicates the gain, ω _d indicates the frequency of the damped vibration, and ζ indicates the damping ratio. In particular, the gain K, the damping vibration frequency ω _d , and the damping ratio ζ are obtained from the waveforms actually measured by the pressure sensor 42. Next, these calculation methods will be described with reference to FIG.

The generation unit 45 calculates the frequency ω _{d of the} damped vibration from the following equation (3).

Here, Tp is an overshoot time, and as shown in FIG. 5, refers to the time from the occurrence of a pressure change to the first extreme value V1 (minimum value V1). Generator 45, the first extreme V1 is confirmed from the input signal, determine the overshoot time Tp, it calculates the frequency omega _d damped oscillation from equation (3).

The frequency ω _{d of the} damped vibration is not limited to that obtained from the equation (3), but the second extreme value M (maximum point M) or the third extreme value V2 (minimum point) from the time of occurrence of the pressure change. It may be calculated based on V2).

  Next, the generation unit 45 calculates the gain K from the following equation (4).

  Since it is such a formula, generation part 45 will calculate gain K from a formula (4), if extreme values V1, M, and V2 are checked from the inputted signal.

  As is apparent from FIG. 5, the gain K can also be obtained from the difference between the pressure value before the pressure change occurs and the pressure value after the pressure change occurs. Therefore, the generation unit 45 may obtain the gain K from the difference when the pressure change occurs and the pressure value becomes a substantially constant value (time 0.4 seconds in FIG. 5). Further, the generation unit 45 may calculate the gain K in consideration of the fourth and subsequent extreme values from the time of occurrence of the pressure change.

  Next, the generation unit 45 calculates the damping ratio ζ from the following equation (5).

  Here, δ is a logarithmic decay rate, and m is the number of periods. In the case of Expression (5), the number of periods m is “0.5”.

  Since it is such a formula, generation part 45 will compute damping ratio ζ from formula (5), if extreme values V1 and M are confirmed from the inputted signal.

As described above, the generation unit 45 calculates the gain K, the frequency ω _{d of the} damped vibration, and the damping ratio ζ, and obtains the vibration waveform expression from Expression (2). Then, the gas leak / gas appliance determination unit 43c calculates a continuous NCC according to the equation (1) from the obtained equation and the input pressure waveform.

Here, the generation unit 45 may calculate the frequency ω _{d of the} damping vibration and the damping ratio ζ. That is, the vibration waveform shown in FIG. 5 tends to depend on the flow rate at the time of gas leakage. For this reason, the generation unit 45 stores in advance an equation that includes only the flow rate value as a variable, and substitutes the flow rate value measured by the flow rate sensor 41 into this equation to obtain the frequency ω _{d of the} damping vibration and the damping ratio ζ. You may make it ask.

Specifically, the generation unit 45 obtains the frequency ω _{d of the} damping vibration and the damping ratio ζ from the following formula (6).

Here, L is a flow rate value, and a ₁ , a ₂ , b ₁ , and b ₂ are constants. In this way, the calculation amount may be reduced by obtaining from Expression (6), and the calculation process may be simplified. There is a certain correlation between the flow rate and the pressure. For this reason, instead of the equation (6), an equation including only the pressure value as a variable may be stored, and the frequency ω _{d of the} damping vibration and the damping ratio ζ may be obtained from this equation.

  Furthermore, in this case, the generation unit 45 desirably calculates the gain K from the difference between the pressure value before occurrence of the pressure change and the pressure value after occurrence of the pressure change without calculating the gain K from Expression (4). This is because the amount of calculation can be further reduced.

  Next, the gas leak and the determination of the used gas appliance 10 by the second method will be described in detail. The spectrum data storage unit 47 shown in FIG. 2 is expected to be obtained in spectral data obtained by Fourier transforming a waveform predicted to be obtained in a minute time immediately after the occurrence of gas leakage, and in a minute time immediately after use of each gas appliance 10. Spectral data obtained by Fourier transform of the waveform to be stored is stored.

  FIG. 9 is a graph showing spectrum data obtained by Fourier transforming a pressure waveform when a gas leak occurs, and FIG. 10 is a spectrum obtained by Fourier transforming the pressure waveform when a gas table is used. It is a graph which shows data. FIG. 11 is a graph showing spectral data obtained by Fourier transforming the pressure waveform when the gas BF bath is used.

  As shown in FIG. 9, when a gas leak occurs, the obtained pressure waveform contains almost no frequency component of 20 Hz or more. Further, as shown in FIG. 10, when a gas table is used, the obtained pressure waveform contains almost no frequency component of 20 Hz or more, but tends to show a large amplitude in a frequency component near about 10 Hz. . Moreover, as shown in FIG. 11, when a gas BF bath is used, the obtained pressure waveform tends to show a slightly large amplitude in a frequency component of 70 Hz to 100 Hz. In addition, the peak which exists in 60-Hz vicinity in FIGS. 9-11 is the noise by a commercial power source.

  Reference is again made to FIG. The spectrum data storage unit 47 stores spectrum data as shown in FIGS. Then, the gas leak / gas appliance determination unit 43c determines the gas leak and the gas appliance 10 to be used based on the spectrum data. Specifically, the gas leak / gas appliance determination unit 43c obtains a pressure waveform in a minute time, and then performs Fourier transform on the waveform to generate spectrum data. After generating the spectrum data, the gas leak / gas appliance determination unit 43c reads the stored contents of the spectrum data storage unit 47 and identifies the stored spectrum data that is closest to the generated spectrum data. If the identified spectral data indicates a gas leak, the gas leak / gas appliance determination unit 43c determines that a gas leak has occurred. If the specified spectrum data is not a gas leak, the gas leak / gas appliance determination unit 43c determines that the gas appliance 10 indicated by the specified spectrum data has been used. In particular, the gas leak / gas appliance determination unit 43c determines that the gas appliance 10 accompanied by a flash fire has been used when the gas appliance 10 indicated by the specified spectrum data is a gas table.

  Reference is again made to FIG. The trigger signal generator 44 detects a change in gas flow rate or gas pressure and outputs a trigger signal. For example, the trigger signal generator 44 includes a differentiation circuit, and detects a change greater than a predetermined value by the differentiation circuit.

  The trigger signal is input to each of the sensors 41 and 42 and the sampling time adjustment unit 43d. When the trigger signal is input, the sampling time adjustment unit 43d shortens the sampling time from a predetermined normal sampling time (for example, 2 seconds for the flow rate and 10 seconds for the pressure). At this time, the determination unit 43 shortens the sampling time by a minute time. Thereby, the determination part 43 measures the waveform in minute time in detail. That is, high-speed sampling is performed in order to make the judgment by the gas leak / gas appliance judgment unit 43c accurate. In addition, when a trigger signal is input, each sensor 41, 42 outputs a signal in accordance with high-speed sampling. In addition, the drive current of the sensors 41 and 42 in the normal state may be reduced, and the drive current may be increased to the normal current after the trigger signal is input.

  Further, the sampling time adjusting unit 43d makes the sampling time of at least one of the gas flow rate and the gas pressure longer than the normal sampling time until the trigger signal is generated by the trigger signal generating unit 44, for example, 10 seconds for the flow rate. Keep it as Here, the case where no trigger signal is generated and the flow rate or pressure does not change more than a predetermined amount can be said to be a case where the flow rate or pressure is stable and the necessity for measurement is small. Therefore, in this embodiment, the power consumption is reduced by increasing the sampling time in such a case.

  The flow rate value storage unit 48 stores the flow rate value due to hot water when the low flow rate determination unit 43a determines that the minute flow rate F1 is a flow rate due to hot water. For this reason, when the flow rate value and the flow rate value within the specified range are detected after the flow rate value of the hot water is stored in the flow rate value storage unit 48, the hot water determination unit 43 a Judge as flow rate. As a result, it is possible to quickly determine the torch without observing the flow rate transition as shown in FIG.

  Next, a microleakage determination method according to the present embodiment will be described. FIG. 12 is a flowchart illustrating an example of the minute leak determination method according to the present embodiment. As shown in FIG. 12, first, the determination unit 43 determines whether or not there is a minute flow F1 based on a signal from the flow sensor 41 (S1). If it is determined that there is no minute flow F1 (S1: NO), this process is repeated until it is determined that there is a minute flow F1.

  When it is determined that the minute flow rate F1 is present (S1: YES), the hot water determination unit 43a determines whether or not the flow value value at the time of hot fire is stored in the flow value storage unit 48 (S2). If it is determined that it is not stored (S2: NO), the process proceeds to step S4.

  When it is determined that it is stored (S2: YES), the flash fire determination unit 43a determines whether or not the minute flow rate F1 is within the specified range of the flow rate value stored in the flow rate value storage unit 48 (S3). . If it is determined that it is within the specified range (S3: YES), the process proceeds to step S5.

  On the other hand, when it is determined that it is not within the specified range (S3: NO), the flash fire determination unit 43a determines whether or not there is a flow rate transition as shown in FIG. 3 (S4). When it is determined that the flow rate has changed (S4: YES), the process proceeds to step S5.

  If it is determined that the flow rate has not changed (S4: NO), the gas leak / gas appliance determination unit 43c determines whether or not the gas appliance 10 accompanied by a fire is used (S6). When it is determined that the gas appliance 10 accompanied by hot water is used (S6: YES), the process proceeds to step S5.

  On the other hand, when it is determined that the gas appliance 10 accompanied by a torch is not used (S6: NO), the minute leak determination unit 43b determines that the minute flow F1 is caused by the minute leak (S7). Thereafter, the process shown in FIG. 12 ends.

  In step S5, the hot water determination unit 43a determines that the minute flow rate F1 is a flow of hot water (S5). Then, the hot water determination unit 43a determines again whether or not the flow value at the time of the hot fire is stored in the flow value storage unit 48 (S8). If it is determined that it is stored (S8: YES), the process shown in FIG. 12 ends. On the other hand, when it is determined that it is not stored (S8: NO), the flow value storage unit 47 stores the minute flow F1 (S9), and the process shown in FIG. 12 ends.

  In addition, it is judged as shown to FIGS. 13-15 whether the process shown to step S6, ie, the gas appliance 10 with a torch, was used. At this time, in the gas meter 40 according to the present embodiment, determination is made not only on whether or not the gas appliance 10 accompanied by a fire is used, but also on gas leakage (excluding minute leakage) and the gas appliance 10 used.

  FIG. 13 is a basic flowchart of gas leak / gas appliance determination. First, when a gas leak or the gas appliance 10 is used, a change greater than a predetermined value occurs in the gas flow rate and the gas pressure. Therefore, the determination unit 43 determines whether or not a trigger signal is input as shown in FIG. 13 (S11). If it is determined that the trigger signal has not been input (S11: NO), this process is repeated until it is determined that the trigger signal has been input.

  On the other hand, if it is determined that the trigger signal has been input (S11: YES), the sampling time adjustment unit 43d shortens the sampling time from the normal sampling time and measures the pressure with the shortened sampling time (S12). Specifically, the sampling time is reduced from 10 seconds to 1 microsecond.

  Thereafter, the gas leak / gas appliance determination unit 43c determines whether or not a minute time has elapsed (S13). If it is determined that the minute time has not elapsed (S13: NO), the process proceeds to step S12. In step S12, the pressure sampling time is shortened, but instead of the pressure sampling time, the flow rate sampling time may be shortened.

  When it is determined that a minute time has elapsed (S13: YES), the determination unit S14 performs a gas leak / gas appliance determination (S14). By this gas leak / gas appliance determination, the gas leak and the gas appliance 10 to be used are determined, and it is determined whether or not the gas appliance 10 accompanied by a fire is used. Then, the process shown in FIG. 13 ends.

FIG. 14 is a first flowchart showing details of the gas leakage / gas appliance determination shown in step S14 of FIG. 13, and shows the first method. First, the generation unit 45 determines the frequency ω _{d of the} damped vibration, the gain K, and the damping ratio ζ (S21). At this time, the generation unit 45 may calculate the frequency ω _{d of the} damped vibration, the gain K, and the damping ratio ζ based on the equations (3) to (5) or may be obtained from the equation (6). Good.

Next, the generating unit 45 generates a gas leakage vibration waveform based on the second-order delay step response equation from the damping vibration frequency ω _d , gain K, and damping ratio ζ determined in step S21 (S22). ). At this time, the generating unit 45 generates the gas leakage vibration waveform by substituting the damping vibration frequency ω _d , the gain K, and the damping ratio ζ determined in step S21 into the equation (2).

  Then, the gas leak / gas appliance determination unit 43c calculates the continuous NCC from the equation (1) based on the gas leak vibration waveform determined in step S22 and the waveform including the measurement value measured in step S12 of FIG. Is calculated (S23). Next, the gas leak / gas appliance determination unit 43c determines a representative value of the continuous NCC and determines whether the representative value is equal to or greater than a threshold value (S24).

  When it is determined that the representative value is greater than or equal to the threshold (S24: YES), the gas leak / gas appliance determination unit 43c determines that a gas leak has occurred (S25). Thereafter, the process shown in FIG. 14 ends.

  When it is determined that the representative value is not equal to or greater than the threshold value (S24: NO), the gas leakage / gas appliance determination unit 43c reads the similarity transition data for each gas appliance from the similarity transition storage unit 46 (S26). Next, the gas leakage / gas appliance determination unit 43c identifies the gas appliance 10 to be used by specifying the closest NCC data calculated in step S23 among the continuous NCC data for each gas appliance read in step S26. (S27). If it is determined in step S27 that the gas appliance 10 accompanied by a fire is used, it is determined as “YES” in step S6 of FIG. Then, the process shown in FIG. 14 ends.

  FIG. 15 is a second flowchart showing details of the gas leak / gas appliance determination shown in step S14 of FIG. 13, and shows the second method. As shown in FIG. 15, first, the gas leak / gas appliance determination unit 43c performs Fourier transform on the waveform of the gas pressure measured in step S12 of FIG. 13 (S31).

  Thereafter, the gas leak / gas appliance determination unit 43c reads the spectrum data at the time of occurrence of the gas leak stored in the spectrum data storage unit 47 (S32). Then, the gas leak / gas appliance determination unit 43c calculates the similarity between the spectrum data obtained by the Fourier transform in step S31 and the spectrum data read in step S32 (S33). This similarity may be the above NCC, or may be calculated by another calculation method. Next, the gas leak / gas appliance determination unit 43c determines whether or not the similarity calculated in step S33 is greater than or equal to a specific value (S34).

  If it is determined that the similarity calculated in step S33 is greater than or equal to a specific value (S34: YES), the gas leak / gas appliance determination unit 43c determines that a gas leak has occurred (S35). Then, the process shown in FIG. 15 ends.

  By the way, when it is determined that the similarity calculated in step S33 is not equal to or greater than a specific value (S34: NO), the gas leak / gas appliance determination unit 43c reads out the spectrum data for each gas appliance 10 (S36). The similarity with the spectrum data is calculated (S37). Then, the gas leak / gas appliance determination unit 43c determines that the type of gas appliance 10 indicated by the spectrum data having the maximum similarity is used (S38). If it is determined in step S38 that the gas appliance 10 accompanied by hot fire has been used, “YES” is determined in step S6 of FIG. Then, the process shown in FIG. 15 ends.

  In the processing of steps S37 and S38 shown in FIG. 15, it is determined that the gas appliance 10 indicated by the highest spectrum data is used by obtaining the similarity to all the spectrum data stored for each gas appliance 10. However, the present invention is not limited to this, and the degree of similarity with the stored spectrum data for each gas appliance 10 is sequentially obtained, and the gas appliance 10 indicated by the spectrum data is obtained when the degree of similarity becomes a predetermined value or more. It may be determined that it has been used, and thereafter the calculation of the similarity may be stopped. This is because by doing so, the number of similarities calculated can be reduced, leading to a reduction in power consumption.

  Furthermore, in this embodiment, the waveform obtained by the electrical signal from the pressure sensor 42 is Fourier transformed to determine the type of the gas appliance 10 and to determine the gas leakage. However, since there is a certain correlation between the pressure and the flow rate, the waveform obtained by the electrical signal from the flow rate sensor 41 is Fourier transformed to determine the type of the gas appliance 10 and to determine the gas leak. Good.

  As described above, according to the gas meter 40 and the minute leakage determination method according to the present embodiment, when a minute flow rate is detected within a predetermined time after a flow rate exceeding the minute flow rate is detected, the minute flow rate is determined to be a flow rate due to the fire. To do. Here, in the gas appliance 10 (for example, a gas stove or a gas table) that accompanies a torch, first, a large flow rate flows at the time of ignition, and then a slight flow rate tends to flow as a torch by adjusting the heating power. As described above, the flow rate of the gas appliance 10 accompanied by a hot flash shows the above transition. For this reason, when this flow rate transition is obtained, it can be inferred that the minute flow rate is not due to minute leakage but due to hot fire. Therefore, when such a flow rate transition is observed, it is possible to improve the determination accuracy of the minute leak by determining that the minute flow rate is not due to the minute leak.

  In addition, it is determined whether or not the gas appliance 10 accompanied by hot water is used, and when it is determined that the gas appliance 10 accompanied by hot water is used, it is determined that the minute flow rate is caused by hot water. For this reason, when use of the gas appliance 10 accompanied by a torch is judged, the possibility that the further minute leak has generate | occur | produced can be denied. Therefore, it is possible to further improve the accuracy of determining a minute leak.

  In addition, it is determined whether or not the gas appliance 10 accompanied by a fire is used based on a waveform measured during a minute time since a predetermined change in at least one of the flow rate and the pressure. Here, when the use of the gas appliance 10 is started, a waveform unique to the gas appliance tends to be shown in a minute time immediately after the start (for example, 2 seconds at the maximum). For this reason, the gas appliance 10 accompanied by a hot fire can be judged in a short time by judging the gas appliance accompanied by a hot fire based on the waveform in this minute time.

  In addition, a trigger signal is generated when at least one of the flow rate and pressure changes more than a predetermined value, and when the trigger signal is generated, the sampling time of at least one of the flow rate and pressure is shortened by a minute time. For this reason, when acquiring the waveform in a minute time, it is possible to prevent the waveform from leaking.

  Further, the sampling time of at least one of the flow rate and the pressure is set longer than the normal sampling time until the trigger signal is generated. Here, the case where no trigger signal is generated and the flow rate or pressure does not change more than a predetermined amount can be said to be a case where the flow rate or pressure is stable and the necessity for measurement is small. Therefore, in such a case, power consumption can be reduced by increasing the sampling time.

  In addition, when it is determined that the minute flow rate is the flow rate due to hot flash, the flow rate value due to the hot fire is stored, and when the stored flow rate value due to hot fire and the flow rate value within the specified range are detected, the flow rate within the specified range is Judged to be the flow rate due to hot water. As described above, since the flow rate value of the torch is stored, it is possible to further improve the accuracy of determination of minute leakage.

  As described above, the present invention has been described based on the embodiment, but the present invention is not limited to the above embodiment, and may be modified without departing from the gist of the present invention.

  In the present embodiment, the minute leak determination device is the gas meter 40, but the present invention is not limited to this, and the minute leak determination device may be configured separately from the gas meter 40.

  Further, in the present embodiment, the similarity transition is calculated by the equation (1). However, the present invention is not limited to this, and the similarity transition may be calculated by another method.

  In the present embodiment, the gas leak / gas appliance determination unit 43c determines that the similarity transition storage unit 46 does not include any data that is close to the calculated continuous NCC among the continuous NCC data stored in the similarity transition storage unit 46. It may be determined that there is a shortage in the gas appliance 10 indicated by the continuous NCC data stored in. Similarly, the spectral data may be determined to be insufficient in the gas appliance 10.

  In this embodiment, the example in which the fuel gas is LP gas has been described. However, the present invention is not limited to this, and the present invention can also be applied to the case of city gas.

  In the present embodiment, the minute time is set to 2 seconds at the maximum, but the present invention is not limited to this and may be a longer time such as several tens of seconds.

  Further, in the present embodiment, the gas leak / gas appliance determination unit 43c calculates the similarity in the entire frequency range of the spectrum data. Good. For example, since the water heater has a feature that a large amplitude can be obtained in the spectrum data even in a frequency range of 100 Hz or higher, the gas appliance 10 to be used is also specified by calculating the similarity of the spectral data in the frequency range of 100 Hz or higher. be able to. In this way, the calculation amount can be reduced by calculating the similarity only in a part of the frequency range.

  Further, the gas leak / gas appliance determination unit 43c determines the gas leak and the gas appliance 10 to be used from the similarity transition (continuous NCC) and the spectrum data. 7 may be directly stored, and the gas leakage and the gas appliance 10 to be used may be determined from the similarity between the waveforms. Furthermore, the gas leak and the gas appliance 10 to be used may be determined from the direct characteristics of the waveform such as a specific point of the waveform.

  Furthermore, in this embodiment, the gas leak / gas appliance determination unit 43c determines the used gas appliance 10 based on the waveform obtained during the minute time from the time t1 in FIG. This is because, as described above, the gas appliance 10 shows a specific vibration waveform for each gas appliance 10 in a minute time immediately after the start of use. However, the present invention is not limited to this, and the used gas appliance 10 may be determined based on the waveform obtained during the minute time from time t4. This is because the gas appliance 10 exhibits a specific vibration waveform for each gas appliance 10 even during a very short time immediately after the end of use, as at the start of use.

  When determining the gas appliance 10 from the vibration waveform obtained during the minute time immediately after the end of use, the sampling time adjustment unit 43d shortens the sampling time from the normal sampling time by the minute time immediately after the end of use. Is desirable. This is because it is possible to prevent the leakage of the vibration waveform obtained during the minute time immediately after the end of use.

DESCRIPTION OF SYMBOLS 1 ... Gas supply system 10 ... Gas appliance 20 ... Regulator 31 ... 1st piping 32 ... 2nd piping 40 ... Gas meter (micro leak judgment apparatus)
41 ... Flow sensor 42 ... Pressure sensor 43 ... Determining unit 43a ... Torch determining unit (Torch determining unit)
43b ... Micro leak judgment unit (micro leak judgment means)
43c ... Gas leakage / gas appliance determination unit (gas appliance determination means)
43d ... Sampling time adjusting section (sampling time adjusting means)
44 ... Trigger signal generator (trigger signal generator)
45 ... generating unit 46 ... similarity transition storage unit 47 ... spectrum data storage unit 48 ... flow rate value storage unit (storage means)

Claims (4)

It is a micro leak judgment device that judges micro gas leaks,
When the minute flow rate is detected within a predetermined time after the flow rate exceeding the minute flow rate is detected, the flame determination means determines that the minute flow rate is a flow rate due to the flame,
A minute leakage judgment means for judging whether the minute flow rate is a flow rate due to minute leakage,
The micro leak judging device does not judge that the micro flow rate is caused by a micro leak when the micro flow judging unit judges that the micro flow rate is a flow rate due to the fire. Further comprising a gas appliance judging means for judging whether or not a gas appliance accompanied by a fire is used,
2. The slight leakage according to claim 1, wherein when the gas appliance determining means determines that a gas appliance accompanied by a fire is used, the microfire determining unit determines that the micro flow rate is a flow rate due to the hot fire. Judgment device. In the case where the minute flow rate is determined to be a flow rate due to the fire, the storage device further includes a storage unit that stores a flow rate value due to the fire.
The said flash fire judging means judges that the flow rate within the specified range is the flow rate due to the hot fire when the flow value by the hot fire stored in the storage means and the flow value within the specified range are detected. The microleakage determination apparatus according to claim 1 or claim 2. A method for determining a slight leakage of gas,
When the micro flow rate is detected within a predetermined time after the flow rate exceeding the micro flow rate is detected, the fire determination step when the micro flow rate is determined to be the flow rate by the fire,
And a minute leakage determination step for determining whether the minute flow rate is a flow rate due to minute leakage,
In the microleakage determination step, the microleakage determination method is characterized in that if the microflow rate is determined to be a flow rate due to a fire, the microflow rate is not determined to be a microleakage.

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