JP2011099690A - Gas leak determination device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas leak determination device and method, which determines more rapidly a gas leak. <P>SOLUTION: A gas meter 40 is equipped with: an input part 43a for thereinto inputting signals from a pressure sensor 41 and a flow sensor 42; a generator 43b for storing vibration waveforms of a measured value at the time of gas leak; a similarity transition calculator 43c for calculating continuity NCC (Normalized Cross Correlation) between the waveforms of the signals from the sensors 41 and 42 input by the input part 43a and the vibration waveforms of the gas leak stored by the generator 43b; and a determiner 43d for determining that a gas leak has arisen in cases where the representative values of similarity transition calculated by the similarity transition calculator 43c are equal to or more than a threshold. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  Conventionally, a gas appliance discriminating apparatus that monitors a flow rate and a pressure and discriminates a gas appliance or a gas leak based on a monitoring result has been proposed. According to this apparatus, the gas leakage is determined from the magnitude of the flow rate and the correlation between the flow rate, the pressure, and the temperature (see, for example, Patent Documents 1 to 3).

  Further, there has been proposed a gas appliance discriminating apparatus that determines a gas appliance or a gas leak based on instantaneous flow rate data, instantaneous flow rate differential value, pressure amount data, and pressure time differential value. According to this apparatus, the gas appliance in use is specified based on the instantaneous flow rate data, etc., and the continuous use time of the specified gas appliance is monitored, and it is determined that the gas leaks when the continuous use time is excessive ( For example, see Patent Document 4).

  In addition, there has been proposed a gas appliance discriminating apparatus that obtains an output resistance from a differential value and an integral value of a flow rate and a pressure, and judges a gas leak based on the output resistance. According to this device, based on the theory that the flow rate and the pressure are constant when the gas leaks, it is determined that the gas leaks when the output resistance does not change for a certain period of time (see, for example, Patent Document 5). ).

  Further, there has been proposed a gas meter that detects a gas leak when a flow rate is detected and does not coincide with a gas flow rate characteristic stored in advance. In particular, in this gas meter, the shutoff valve is closed to refill the gas flow path, and the gas flow rate characteristic is obtained from the flow rate of the gas flowing when the gas is refilled to determine the gas leakage. Further, in this gas meter, it is possible to determine a gas leak by detecting the pressure as in the case of the flow rate (see, for example, Patent Document 6).

JP 2008-101950 A JP 2008-10951 A JP 2008-107301 A JP 2008-101952 A JP 2008-111676 A JP 2008-111672 A

  However, in the devices described in Patent Documents 1 to 3, the flow rate is measured once every about 2 seconds, and the point is added based on the magnitude of the flow rate and the correlation between the flow rate, the pressure, and the temperature. The gas leak is judged based on the points. For this reason, a comparatively long-term measurement is required until the point addition is completed, and the gas leak judgment is not quick.

  Moreover, in the apparatus of patent document 4, after discriminating a gas appliance, it will judge a gas leak based on a continuous use time. For this reason, it is necessary to monitor the continuous use time, and the gas leakage judgment is not quick.

  Also in the apparatus of Patent Document 5, if it is not detected that the output resistance does not change for a certain period of time, it is not possible to determine gas leakage, and it is necessary to monitor the output resistance during a certain period of time. It was lacking.

  Further, in the apparatus of Patent Document 6, it is necessary to refill the gas flow path in order to determine gas leakage, and in order to obtain characteristics, the gas flow rate and pressure are set to 5 for example during the refilling period. It is necessary to measure about seconds. For this reason, the gas leakage judgment is not quick.

  The present invention has been made to solve such conventional problems, and an object of the present invention is to provide a gas leak determination device and a gas leak capable of improving the speed of gas leak determination. It is to provide a judgment method.

  The gas leak judgment device of the present invention includes at least a pressure sensor that outputs a measurement value signal corresponding to the gas pressure in the flow path, and a flow rate sensor that outputs a measurement value signal corresponding to the gas flow rate in the flow path. Input means for inputting a signal from one measurement sensor, generation means for generating a gas leakage vibration waveform when gas leakage is assumed, and waveform and generation of a signal from the measurement sensor input by the input means Similarity transition calculation means for calculating similarity transition with the gas leakage vibration waveform generated by the means, and determination means for determining occurrence of gas leakage based on the similarity transition calculated by the similarity transition calculation means And.

  According to this gas leak determination apparatus, the similarity transition between the waveform of the signal from the measurement sensor and the generated gas leak vibration waveform is calculated, and the occurrence of gas leak is determined based on the calculated similarity shift. Here, the present inventors have found that vibrations occur in the measured values of pressure and flow rate in a very short time immediately after the occurrence of gas leakage. For this reason, the degree of similarity between the waveform of the signal from the measurement sensor and the generated gas leakage vibration waveform tends to be high, and the degree of similarity also tends to show a high value as a whole. Therefore, gas leakage can be determined from this feature. Moreover, since the data necessary for this determination is data for a minute time, it is possible to determine a gas leak in a short time. Accordingly, it is possible to improve the speed of the gas leak determination.

  In the gas leak judgment device of the present invention, the gas leak vibration waveform generated by the generating means is generated based on a second-order lag step response equation including the frequency, gain, and damping ratio of the damped vibration. It is preferable.

  According to this gas leak determination device, the generated gas leak vibration waveform is generated based on a second-order delay step response equation including the frequency, gain, and damping ratio of the damped vibration. Here, at the time of gas leakage, the value transitions from the flow rate value and pressure value before the occurrence of gas leakage to the flow rate value and pressure value after the occurrence of gas leakage. For this reason, it is actually better to store the gas leakage vibration waveform generated based on the second-order lag step response expression than to store the vibration waveform determined from the simple damped vibration expression. Appropriate gas leak vibration waveform along can be stored.

  Moreover, in the gas leak judgment apparatus of the present invention, it is preferable that the frequency of the damped vibration is calculated from an equation that includes only a measured value as a variable.

  According to this gas leak judgment device, the frequency of the damped vibration is calculated from an equation that includes only the measured value as a variable. Here, in order to calculate the frequency of the damped vibration, it is necessary to measure the overshoot time. The calculation can be simplified.

  In the gas leak determination device of the present invention, it is preferable that the attenuation ratio is calculated from an equation that includes only a measured value as a variable.

  According to this gas leak determination device, the attenuation ratio is calculated from an equation that includes only the measured value as a variable. Here, in order to calculate the attenuation ratio, the extreme value of the vibration waveform is required, but since it is calculated from an equation that includes only the measured value as a variable, the extreme value calculation is not necessary, and the calculation of the attenuation ratio Simplification can be achieved.

  In the gas leak judgment apparatus of the present invention, the gain in the second-order delay step response equation is K, the first extreme value in the waveform of the signal from the measurement sensor is V1, and the second extreme value is M. In the case where the third extreme value is V2, the gain K is preferably calculated from an arithmetic expression of K = (V1 + 2M + V2) / 4.

  According to this gas leak judgment device, the gain is K in the second-order delay step response equation, the first extreme value in the waveform of the signal from the measurement sensor is V1, the second extreme value is M, the third When the extreme value of V2 is V2, the gain K is calculated from an arithmetic expression of K = (V1 + 2M + V2) / 4. In this way, by using the first to third extreme values in calculating the gain K, the gain K can be calculated without monitoring the measurement value until the vibration convergence, and the gain K can be calculated at an early stage. it can. In particular, in homes where LP gas is used, a regulator is provided, and when the gas leaks, the pressure of the regulator adjusts the pressure of the measurement value due to factors other than the gas leak. Therefore, the gain calculation accuracy can be improved by calculating the gain K from the extreme value of the vibration waveform before the pressure adjustment by the adjuster of the first to third extreme values.

  Further, in the gas leak judgment device of the present invention, when the attenuation ratio is ζ and the number of periods from the first extreme value V1 to the second extreme value M is m in the second-order lag step response equation, the attenuation is The ratio ζ is preferably calculated from an arithmetic expression of δ = [(1 / m) Ln {(V1−K) / (M−K)}] / 2π.

  According to this gas leak judgment device, when the attenuation ratio is ζ and the number of periods from the first extreme value V1 to the second extreme value M is m in the second-order delay step response equation, the attenuation ratio ζ is , Δ = [(1 / m) Ln {(V1−K) / (M−K)}] / 2π. In this way, by using the first and second extreme values in calculating the damping ratio ζ, the damping ratio ζ can be calculated without monitoring the measured value until the vibration convergence, and the damping ratio ζ is calculated at an early stage. can do. In particular, in homes where LP gas is used, a regulator is provided, and when the gas leaks, the pressure of the regulator adjusts the pressure of the measurement value due to factors other than the gas leak. For this reason, by calculating the damping ratio ζ from the extreme values of the vibration waveform before pressure adjustment by the adjuster of the first and second extreme values, it is possible to improve the accuracy of gain calculation.

  Further, the gas leak judgment device of the present invention further comprises storage means for previously storing similarity transition data between a measured value when each gas appliance is used and a gas leak vibration waveform generated by the generating means. When the determination means determines that no gas leak has occurred based on the similarity transition calculated by the similarity transition calculation means, the determination means determines that one of the gas appliances has been used, and the storage means It is preferable to determine that the gas appliance indicated by the similarity transition data that is closest to the calculated similarity transition is used among the similarity transition data stored in the above.

  According to this gas leak determination apparatus, when it is determined that no gas leak has occurred based on the calculated similarity transition, it is determined that one of the gas appliances has been used. Here, the case where the similarity transition is calculated is a case where a gas flow occurs, and in most cases, a gas leak occurs or a gas appliance is used. For this reason, when it is determined that no gas leak has occurred, it is determined that one of the gas appliances has been used.

  Further, similarity transition data between a measured value when each gas appliance is used and the generated gas leakage vibration waveform is stored in advance. Here, the degree of similarity between the gas leakage vibration waveform and the signal of the measurement value when using the gas appliance cannot be said to be high, but when the similarity transition is observed, the characteristics of each gas appliance tend to appear. The storage means stores similarity transition data for each gas appliance having such characteristics.

  In addition, when it is determined that no gas leakage has occurred, it is determined that the gas appliance indicated by the similarity transition data closest to the calculated similarity transition is used among the stored similarity transition data. In this way, the determination means pays attention to the feature of similarity transition, and can determine the used gas appliance from the transition of similarity even if no gas leakage occurs. Therefore, it is possible to determine the used gas appliance and enhance security and service.

  The gas leak determination apparatus according to the present invention further includes a correction unit that calculates a corrected similarity transition by subtracting an average value of the entire similarity transition from each similarity calculated by the similarity transition calculating unit, It is preferable that the storage unit updates the similarity transition data stored in advance based on the corrected similarity transition corrected by the correcting unit.

  According to this gas leak judgment device, a corrected similarity transition is calculated by subtracting the average value of the entire similarity transition from each calculated similarity, and a pre-stored similarity transition is calculated based on the corrected similarity transition. Update the data. Here, there are many cases where the piping state is different in each home. Differences also occur in each household etc. with respect to the similarity transition calculated from such differences in the piping state. In particular, this difference affects the level of similarity, and can be reduced by subtracting the average value of the overall similarity transition. Therefore, by updating the similarity transition data stored in advance based on the corrected similarity transition, the determination accuracy of the gas appliance can be improved in accordance with the stored similarity transition data for each home or the like. it can.

  Further, in the gas leak judgment device of the present invention, a first storage means for storing in advance similarity degree transition data between a measured value when each gas appliance is used and a gas leak vibration waveform generated by the generating means; And a second storage means for storing in advance similarity transition data between a measured value when it is assumed that there is a gas leak and a gas leak vibration waveform generated by the generation means, and the determination means includes Of the similarity transition data stored in the first and second storage means, the similarity transition data closest to the calculated similarity transition is the similarity transition data stored in the second storage means When it is determined that a gas leak has occurred and the closest similarity transition data is the similarity transition data stored in the first storage means, the similarity transition data indicates It is preferable to determine that the instrument is being used.

  Here, the degree of similarity between the gas leakage vibration waveform and the signal of the measurement value when using the gas appliance cannot be said to be high, but when the similarity transition is observed, the characteristics of each gas appliance tend to appear. The first storage means stores similarity transition data for each gas appliance having such characteristics. Moreover, the similarity between the gas leak vibration waveform and the signal of the measured value at the time of gas leak is high, and when the similarity transition is observed, the similarity transition tends to agree as a whole. The first storage means stores similarity transition data that matches as a whole.

  In addition, among the stored similarity transition data, when the similarity transition data closest to the calculated similarity transition is the similarity transition data stored in the first storage means, the similarity transition data indicates Judge that a gas appliance was used. Thus, the determination means can determine the gas appliance used from the transition of the similarity by paying attention to the feature of the similarity transition. Similarly, if the closest similarity transition data is the similarity transition data stored in the second storage means, it is determined that there is a gas leak. As described above, the determination unit determines that the gas leaks when the similarity transitions as a whole match.

  Therefore, it is possible to determine the used gas appliance and enhance security and service. Furthermore, the gas leakage and the specification of the gas appliance to be used can be performed simultaneously.

  The gas leak determination apparatus according to the present invention further includes a correction unit that calculates a corrected similarity transition by subtracting an average value of the entire similarity transition from each similarity calculated by the similarity transition calculating unit, Preferably, the second storage means updates the similarity transition data stored in advance based on the corrected similarity transition corrected by the correcting means.

  According to this gas leak judgment device, a corrected similarity transition is calculated by subtracting the average value of the entire similarity transition from each calculated similarity, and a pre-stored similarity transition is calculated based on the corrected similarity transition. Update the data. Here, there are many cases where the piping state is different in each home. Differences also occur in each household etc. with respect to the similarity transition calculated from such differences in the piping state. In particular, this difference affects the level of similarity, and can be reduced by subtracting the average value of the overall similarity transition. Therefore, by updating the similarity transition data stored in advance based on the corrected similarity transition, the determination accuracy of the gas appliance can be improved in accordance with the stored similarity transition data for each home or the like. it can.

  Further, in the gas leak judgment device of the present invention, when it is judged that the measurement value has fluctuated based on the measurement value signal input by the input means, the sampling time of the signal from the measurement sensor is measured. It is preferable to further include a sampling time adjusting means that shortens the time compared to before.

  According to this gas leak judging device, when it is judged that the measurement value has fluctuated, it is further provided with a sampling time adjusting means for shortening the sampling time of the signal from the measurement sensor as compared with that before the measurement value fluctuation. The generated vibration waveform can be appropriately measured.

  The gas leak judgment method of the present invention includes at least a pressure sensor that outputs a measurement value signal corresponding to the gas pressure in the flow path, and a flow rate sensor that outputs a measurement value signal corresponding to the gas flow rate in the flow path. An input step of inputting a signal from one measurement sensor, a generation step of generating a gas leak vibration waveform when gas leakage is assumed, and a waveform and generation of the signal from the measurement sensor input by the input means A similarity transition calculation step for calculating a similarity transition with the gas leak vibration waveform generated in the process, and a determination step for determining the occurrence of a gas leak based on the similarity transition calculated in the similarity transition calculation step It is characterized by having.

  According to this gas leak determination method, the similarity transition between the waveform of the signal from the measurement sensor and the generated gas leak vibration waveform is calculated, and the occurrence of gas leak is determined based on the calculated similarity transition. Here, the present inventors have found that vibrations occur in the measured values of pressure and flow rate in a very short time immediately after the occurrence of gas leakage. For this reason, the degree of similarity between the waveform of the signal from the measurement sensor and the generated gas leakage vibration waveform tends to be high, and the degree of similarity also tends to show a high value as a whole. Therefore, gas leakage can be determined from this feature. Moreover, since the data necessary for this determination is data for a minute time, it is possible to determine a gas leak in a short time. Accordingly, it is possible to improve the speed of the gas leak determination.

  ADVANTAGE OF THE INVENTION According to this invention, the gas leak judgment apparatus and the gas leak judgment method which can improve the quickness about gas leak judgment can be provided.

It is a lineblock diagram of a gas supply system containing a gas leak judging device concerning an 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 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 waveform of a simple damping vibration. It is a figure which shows the mode of a pressure fluctuation | variation, Comprising: (a) shows the pressure change at the time of gas leak, (b) has shown the pressure change at the time of gas appliance use. It is a graph which shows continuous NCC at the time of gas leak. It is a graph which shows continuous NCC at the time of water heater use. It is a graph which shows continuous NCC at the time of floor heating use. It is a graph which shows the correction | amendment continuous NCC of a water heater. It is a graph which shows the correction | amendment continuous NCC of floor heating. It is a flowchart which shows an example of operation | movement of the gas meter which concerns on this embodiment. It is a block diagram which shows the detail of the gas meter which concerns on 2nd Embodiment. It is a flowchart which shows an example of operation | movement of the gas meter which concerns on 2nd Embodiment. It is a graph which shows the correction | amendment continuous NCC data of a water heater.

  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 gas leak determination device according to an embodiment of the present invention. The gas supply system 1 supplies a fuel gas to each gas appliance 10 such as a gas stove, a fan heater, a water heater, a floor heater, and a table stove. The gas supply system 1 includes a plurality of gas appliances 10 and a gas supply source regulator. 20, pipes 31 and 32, and a gas meter (gas leak determination device) 40. In the example illustrated in FIG. 1, the gas meter 40 is described as an example of the gas leak determination device, but the gas 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 includes a pressure sensor (measurement sensor) 41, a flow rate sensor (measurement sensor) 42, and a control unit 43. The pressure sensor 41 outputs a measurement value signal corresponding to the gas pressure in the flow path of the gas meter 40. The flow sensor 42 outputs a measurement value signal corresponding to the gas flow rate in the flow path of the gas meter 40.

  The control unit 43 performs a gas leak determination and the like, and includes an input unit (input unit) 43a, a generation unit (generation unit) 43b, a similarity transition calculation unit (similarity transition calculation unit) 43c, and a determination unit (determination). Means) 43d.

  The input unit 43 a functions as an input interface for inputting signals from the pressure sensor 41 and the flow rate sensor 42. Moreover, the production | generation part 43b produces | generates the gas leak vibration waveform at the time of assuming gas leak.

  FIG. 3 is a diagram showing an outline of a gas leakage vibration waveform generated by the generation unit 43b shown in FIG. As illustrated in FIG. 3, the generation unit 43 b 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 (time within 1 second) immediately after the occurrence of gas leakage. For this reason, the generation unit 43b generates a gas leakage vibration waveform based on a second-order delay step response formula as information necessary for leak determination, and the similarity transition calculation unit 43c and the determination unit 43d The occurrence of gas leakage is determined based on the gas leakage vibration waveform generated in 43b.

  FIG. 4 is a diagram showing a waveform of simple damped vibration. As shown in FIG. 4, the waveform of the simple damped vibration is different from the gas leak vibration waveform shown in FIG. When gas leakage actually occurs, the gas pressure decreases and the gas flow rate increases. As described above, the pressure value and the flow rate value transition from the values before the occurrence of gas leakage to the values after the occurrence of gas leakage. Therefore, the gas leak vibration waveform generated in the generation unit 43b is not a waveform determined based on simple damped vibration in which the value does not change after the gas leak occurs before the gas leak occurs, but an equation of a step response with a secondary delay. It can be said that it is desirable that the waveform be determined based on the above.

  In addition, although the production | generation part 43b produces | generates the gas leak vibration waveform of a pressure in the example shown in FIG. 3, even if it produces | generates the gas leak vibration waveform which vibrates as a flow volume rises with progress of time not only in this. 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 similarity transition calculation unit 43c calculates the similarity transition between the waveform of the signal from the sensors 41 and 42 input to the input unit 41a and the gas leakage vibration waveform generated by the generation unit 43b. 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). The similarity degree transition calculation unit 43c obtains a similarity degree transition (hereinafter referred to as continuous NCC) by continuously calculating the similarity degree _RNCC according to the equation (1).

  The determination unit 43d determines the occurrence of gas leakage based on the similarity transition calculated by the similarity transition calculation unit 43c. In particular, in this embodiment, as an example, when the representative value of the similarity transition calculated by the similarity transition calculation unit 43c is equal to or greater than a threshold value, it is determined that a gas leak has occurred. 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, with reference to FIG. 5, the pressure change at the time of a gas leak and use of a gas appliance is demonstrated. FIGS. 5A and 5B are diagrams showing the state of pressure fluctuation, wherein FIG. 5A shows the pressure change when the gas leaks, and FIG. 5B shows the pressure change when the gas appliance is used. As shown in FIG. 5A, 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 43b as shown in FIG. For this reason, the representative value of the similarity transition shows a high value, and the determination unit 43d 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 determination unit 43d determines that a gas leak has occurred when the representative value of the similarity transition calculated by the similarity transition calculation unit 43c is equal to or greater than “0.9”.

  On the other hand, as shown in FIG. 5B, when the gas appliance is used, a vibration waveform different from that at the time of gas leakage is shown. Therefore, it cannot be said that this waveform has a high correlation with the gas leakage vibration waveform generated by the generation unit 43b as shown in FIG. 3, and the representative value of the similarity transition does not indicate a high value. Therefore, the determination unit 43d determines that no gas leak has occurred.

  FIG. 7 is a graph showing continuous NCC when using a water heater, and FIG. 8 is a graph showing continuous NCC when using floor heating. As shown in FIGS. 7 and 8, the continuous NCC immediately after the occurrence of a pressure change when using the gas appliance (near time 0 seconds) shows a value near “1.0”. However, the continuous NCC shows a value lower than “0.9” after time 0.02 seconds, and shows a value much lower than “0.8” after that. Therefore, the determination unit 43d determines that no gas leak has occurred when the representative value of the similarity transition calculated by the similarity transition calculation unit 43c is not “0.9” or more.

  In addition, the case where the change of the pressure or the flow rate occurs is almost when the gas leak occurs or when the gas appliance is used. Therefore, the determination unit 43d desirably determines that the gas appliance 10 is used when the representative value of the similarity transition calculated by the similarity transition calculation unit 43c is not “0.9” or more.

  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 leak determination will be described. If it demonstrates in detail, the production | generation part 43b will produce | generate a gas leak vibration waveform as follows. First, the generation unit 43b stores the following formula (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 41. Next, these calculation methods will be described with reference to FIG.

Generator 43b, from the following equation (3), calculates the frequency omega _d damped oscillation.

Here, Tp is the overshoot time, and as shown in FIG. 5A, it is the time from the occurrence of pressure change to the first extreme value V1 (minimum value V1). Generating unit 43b, when the first extreme V1 is confirmed from the input signal by the input unit 43a, it obtains the excessive time Tp, 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 43b calculates the gain K from the following equation (4).

  Since it is such a formula, generation part 43b will calculate gain K from a formula (4), if extreme values V1, M, and V2 are checked from a signal inputted by input part 43a.

  As is clear from FIG. 5A, the gain K can also be obtained from the difference between the pressure value before the pressure change is generated and the pressure value after the pressure change is generated. Therefore, the generation unit 43b 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. 5A). Furthermore, the similarity degree transition calculation unit 43c may calculate the gain K by taking into account the fourth and subsequent extreme values from when the pressure change has occurred.

Next, the generation unit 43b 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 the equation is such, the generation unit 43b calculates the attenuation ratio ζ from the equation (5) when the extreme values V1 and M are confirmed from the signal input by the input unit 43a.

As described above, the generating unit 43b 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). And the similarity transition calculation part 43c will obtain | require continuous NCC according to Formula (1) from the calculated | required formula and the pressure waveform input by the input part 43a.

Here, the generation unit 43b may calculate the frequency ω _{d of the} damping vibration and the damping ratio ζ as follows. That is, the vibration waveform shown in FIG. 5A tends to depend on the flow rate at the time of gas leakage. For this reason, the generation unit 43b stores in advance an expression that includes only the flow rate value as a variable, and substitutes the flow rate value measured by the flow rate sensor 42 into the expression to obtain the frequency ω _{d of the} damping vibration and the damping ratio ζ. You may make it ask.

Specifically, the generation unit 43b obtains the damping vibration frequency ω _d and the damping ratio ζ from the following equation (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 43b desirably obtains the gain K from the difference between the pressure value before the pressure change occurrence and the pressure value after the pressure change occurrence without calculating the gain K from the equation (4). This is because the amount of calculation can be further reduced.

  Reference is again made to FIG. The determination unit 43d has a gas appliance determination function in addition to the gas leak determination function described above. Next, the gas appliance determination function will be described.

  As shown in FIGS. 7 and 8, the continuous NCC is different between the water heater and the floor heating. That is, the continuous NCC is different for each gas appliance 10 and represents the characteristics of each gas appliance 10. In the present embodiment, the control unit 43 includes a storage unit (storage unit) 43e, and the storage unit 43e previously stores continuous NCC data of measured values and gas leakage vibration waveforms when the gas appliances 10 are used. I remember it. That is, the memory | storage part 43e has memorize | stored the continuous NCC data approximated to what is shown in FIG. 7 about a water heater, and has memorize | stored the continuous NCC data approximated to what is shown in FIG. For other gas appliances 10, the storage unit 43e stores continuous NCC data.

  And when the judgment part 43d judges that the gas leak has not generate | occur | produced, the used gas appliance 10 is judged. At this time, the determination unit 43d 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 storage unit 43e is used.

  Reference is again made to FIG. As shown in FIG. 2, the control unit 43 includes a correction unit (correction unit) 43f. The correction unit 43f is for updating the continuous NCC data stored in the storage unit 43e. As described above, the storage unit 43e stores continuous NCC data for each gas appliance 10 in advance in order to determine the used gas appliance 10. However, the piping state is different in each home. For this reason, even if the same gas appliance 10 is used in different homes, the signal input to the input unit 43a is slightly different. Thereby, even if exactly the same gas appliance 10 is used, there is a slight difference in each household regarding the continuous NCC calculated by the similarity transition calculating unit 43c. And this difference may cause it to be determined that floor heating is used even though a water heater is used in a certain home. Therefore, the control unit 43 according to the present embodiment includes a correction unit 43f. Next, the function of the correction unit 43f will be described.

  First, the correction unit 43f reads the continuous NCC calculated by the similarity transition calculation unit 43c when the determination unit 43d determines that the gas appliance 10 is used instead of gas leakage. Next, the correcting unit 43f subtracts the average value of the entire continuous NCC from each similarity degree indicated by the continuous NCC. Thereby, the correction unit 43f calculates a corrected continuous NCC.

  FIG. 9 is a graph showing the corrected continuous NCC of the water heater, and FIG. 10 is a graph showing the corrected continuous NCC of the floor heating. As shown in FIGS. 9 and 10, the corrected continuous NCC is similar between the solid line and the broken line. Therefore, it can be said that the difference between households has been eliminated.

  Then, the control unit 43 updates the continuous NCC data closest to the corrected continuous NCC with the corrected continuous NCC. More specifically, the control unit 43 compares the corrected continuous NCC obtained by the correcting unit 43f with the continuous NCC data stored in the storage unit 43e, and specifies continuous NCC data to be updated. Then, the control unit 43 updates the identified continuous NCC data with the corrected continuous NCC. When updating, the control unit 43 may bring the continuous NCC data stored in the storage unit 43e closer to the corrected continuous NCC every time the corrected continuous NCC is obtained, or the storage unit every time a plurality of corrected continuous NCCs are obtained. The continuous NCC data stored in 43e may be approximated to the corrected continuous NCC. Further, the control unit 43 may accumulate a predetermined number of corrected continuous NCCs, obtain an average of the accumulated corrected continuous NCCs, and replace the obtained average with the continuous NCC data to be updated.

  Thereby, the continuous NCC data memorize | stored in the memory | storage part 43e can be made into each household, and the determination precision of the gas appliance 10 can be improved.

  Reference is again made to FIG. As shown in FIG. 2, the control unit 43 includes a post-processing unit 43g and a sampling time adjustment unit (sampling time adjustment means) 43h. The post-processing unit 43g executes various processes based on the determination result of the determination unit 43e. Specifically, the post-processing unit 43g closes the shut-off valve or issues an alarm when the determination unit 43d determines that the gas has leaked. Moreover, you may report to a gas management center. On the other hand, when it is determined that the gas appliance 10 has been used by the determination unit 43d and the used gas appliance 10 is specified, the post-processing unit 43g monitors the continuous use time for the gas appliance 10 or uses the gas usage amount. About discounts.

  The sampling time adjustment unit 43 h adjusts the sampling time of the pressure sensor 41 and the flow rate sensor 42. In the gas meter 40 according to the present embodiment, as shown in FIG. 5, it is necessary to measure the measurement value in detail in a minute time. Generally, the pressure sensor 41 has a measurement interval of once every 10 seconds, and the flow sensor 42 has a measurement interval of once every 2 seconds. For this reason, the sampling time adjustment unit 43h shortens this interval. Specifically, when it can be determined that the measured value has changed, the sampling time is shortened to about 1 microsecond, for example, before the measured value is changed. Thereby, detailed measurement in minute time is enabled.

  Next, the operation of the gas meter 40 according to the present embodiment will be described with reference to a flowchart. FIG. 11 is a flowchart showing an example of the operation of the gas meter 40 according to the present embodiment.

  First, the control unit 43 determines whether or not there is a flow rate based on the signal input from the input unit 43a (S1). When it is determined that there is no flow rate (S1: NO), this process is repeated until it is determined that there is a flow rate. On the other hand, when it is determined that there is a flow rate (S1: YES), the process proceeds to step S2. In step S1, instead of determining whether or not there is a flow rate, it may be determined whether or not the pressure has changed.

  In step S2, the sampling time adjustment unit 43h shortens the sampling time and measures the pressure with the shortened sampling time (S2). At this time, the sampling time adjustment unit 43h adjusts so as to measure the pressure at intervals of about 1 microsecond. The measurement time is preferably less than 1 second. This is because the vibration waveform is not observed in the time exceeding 1 second. Further, instead of the pressure sampling time, the flow rate sampling time may be shortened.

Then, after the pressure measurement, the generation unit 43b determines the frequency ω _{d of the} damped vibration, the gain K, and the damping ratio ζ (S3). At this time, the similarity transition calculation unit 43c 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 from the equation (6). You may ask for it.

Next, the generation unit 43b 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 S3 (S4). ). At this time, the generation unit 43b 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 S3 into Expression (2).

  Then, the similarity degree transition calculation unit 43c calculates a continuous NCC from the equation (1) based on the gas leakage vibration waveform determined in step S4 and the waveform including the measurement value measured in step S2 (S5). ). Next, the determination unit 43d determines a representative value of continuous NCC and determines whether the representative value is equal to or greater than a threshold value (S6).

  When it is determined that the representative value is equal to or greater than the threshold value (S6: YES), the determination unit 43d determines that a gas leak has occurred (S7). Then, the post-processing unit 43g issues an alarm or closes the shut-off valve (S8). Thereafter, the process shown in FIG. 11 ends.

  On the other hand, when it is determined that the representative value is not greater than or equal to the threshold (S6: NO), the determination unit 43d determines that the gas appliance 10 has been used (S9). Then, the correcting unit 43f calculates a corrected continuous NCC by subtracting the average value of the entire continuous NCC from each similarity of the continuous NCC calculated in step S5 (S10). Thereafter, the storage unit 43e accumulates the corrected continuous NCC corrected by the correction unit 43f and updates the stored continuous NCC data (S11).

  And the similarity transition calculation part 43c calculates continuous NCC again (S12). At this time, the similarity transition calculation unit 43c calculates a continuous NCC from the equation (1) based on the gas leakage vibration waveform generated in step S4 and the waveform including the measurement value measured in step S2. If the continuous NCC calculated in step S5 is temporarily stored in the storage unit 43e, the process in step S12 can be omitted.

  Next, the determination unit 43d determines that the gas appliance 10 indicated by the continuous NCC data closest to the continuous NCC calculated in step S12 is used among the continuous NCC data stored in the storage unit 43e (S13). ). Thereafter, the post-processing unit 43g executes a security process such as monitoring the continuous use time for the gas appliance 10 being used, or discounts a charge based on the gas usage of the gas appliance 10 being used ( S14). Then, the process shown in FIG. 11 ends.

  Thus, according to the gas meter 40 and the gas leak determination method according to the present embodiment, the similarity transition between the waveform of the signal from the sensors 41 and 42 and the generated gas leak vibration waveform is calculated, and the calculated similarity The occurrence of gas leakage is determined based on the degree transition. Here, the present inventors have found that vibrations occur in the measured values of pressure and flow rate in a very short time immediately after the occurrence of gas leakage. For this reason, the degree of similarity between the waveform of the signal from the sensors 41 and 42 and the generated gas leakage vibration waveform tends to be high, and the degree of similarity also tends to be high overall. Therefore, gas leakage can be determined from this feature. Moreover, since the data necessary for this determination is data for a minute time, it is possible to determine a gas leak in a short time. Accordingly, it is possible to improve the speed of the gas leak determination.

Further, the generated gas leakage vibration waveform is generated based on a second-order delay step response equation including the frequency ω _{d of the} damped vibration, the gain K, and the damping ratio ζ. Here, at the time of gas leakage, the value transitions from the flow rate value and pressure value before the occurrence of gas leakage to the flow rate value and pressure value after the occurrence of gas leakage. For this reason, it is actually better to store the gas leakage vibration waveform generated based on the second-order lag step response expression than to store the vibration waveform determined from the simple damped vibration expression. Appropriate gas leak vibration waveform along can be stored.

Further, the frequency ω _{d of the} damped vibration is calculated from an equation that includes only the measured value as a variable. Here, in order to calculate the frequency ω _d of the damped vibration, it is necessary to measure the overshoot time Tp. However, since the variable is calculated from an expression including only the measured value, the measurement of the overshoot time Tp is not necessary. It is possible to simplify the calculation of the frequency ω _d of the damped vibration.

  Further, the damping ratio ζ is calculated from an equation that includes only measured values as variables. Here, in order to calculate the damping ratio ζ, the extreme value of the vibration waveform is required, but since it is calculated from an expression including only the measured value as a variable, the extreme value calculation is not necessary, and the damping ratio ζ The calculation can be simplified.

  In the second-order delay step response equation, the gain is K, the first extreme value in the waveform of the signal from the sensors 41 and 42 is V1, the second extreme value is M, and the third extreme value is V2. In this case, the gain K is calculated from an arithmetic expression of K = (V1 + 2M + V2) / 4. In this way, by using the first to third extreme values V1, M, and V2 in calculating the gain K, the gain K can be calculated without monitoring the measured values until the vibration convergence, and the gain K can be quickly calculated. Can be calculated. In particular, in a home or the like that uses LP gas, the regulator 20 is provided, and at the time of gas leakage, the pressure adjustment by the regulator 20 causes vibration of the measured value due to factors other than gas leakage. For this reason, the gain calculation accuracy is improved by calculating the gain K from the extreme values V1, M, V2 of the vibration waveform before the pressure adjustment by the adjuster 20 of the first to third extreme values V1, M, V2. Can be planned.

  In the second-order delay step response equation, when the damping ratio is ζ and the number of periods from the first extreme value V1 to the second extreme value M is m, the damping ratio ζ is δ = [(1 / m) Ln {(V1−K) / (M−K)}] / 2π is calculated from an arithmetic expression. In this way, by using the first and second extreme values in calculating the damping ratio ζ, the damping ratio ζ can be calculated without monitoring the measured value until the vibration convergence, and the damping ratio ζ is calculated at an early stage. can do. In particular, in homes where LP gas is used, a regulator is provided, and when the gas leaks, the pressure of the regulator adjusts the pressure of the measurement value due to factors other than the gas leak. For this reason, by calculating the damping ratio ζ from the extreme values of the vibration waveform before pressure adjustment by the adjuster of the first and second extreme values, it is possible to improve the accuracy of gain calculation.

  When it is determined that no gas leak has occurred based on the calculated similarity transition, it is determined that one of the gas appliances 10 has been used. Here, the case where the similarity transition is calculated is a case where a gas flow occurs, and in most cases, a gas leak occurs or a gas appliance is used. For this reason, when it is determined that no gas leak has occurred, it is determined that one of the gas appliances 10 has been used.

  Further, similarity transition data between a measured value when each gas appliance 10 is used and a generated gas leakage vibration waveform is stored in advance. Here, the degree of similarity between the gas leakage vibration waveform and the signal of the measurement value when using the gas appliance cannot be said to be high, but when the similarity transition is observed, the characteristics of each gas appliance tend to appear. The storage unit 43e stores similarity transition data for each gas appliance having such characteristics.

  In addition, when it is determined that no gas leakage has occurred, it is determined that the gas appliance 10 indicated by the similarity transition data closest to the calculated similarity transition is used among the stored similarity transition data. In this way, the determination unit 43d pays attention to the feature of similarity transition, and can determine the used gas appliance 10 from the transition of similarity even when no gas leakage occurs. Therefore, it is possible to determine the used gas appliance and enhance security and service.

  Further, the corrected continuous NCC is calculated by subtracting the average value of the entire continuous NCC from each calculated similarity, and the previously stored continuous NCC data is updated based on the corrected continuous NCC. Here, there are many cases where the piping state is different in each home. Regarding the continuous NCC calculated from the difference in the piping state, a difference occurs in each household. In particular, this difference affects the high degree of similarity, and can be reduced by subtracting the average value of the entire continuous NCC. Therefore, by updating the continuous NCC data stored in advance based on the corrected continuous NCC, the determination accuracy of the gas appliance 10 can be improved in accordance with the stored continuous NCC data for each home or the like.

  In addition, when it is determined that the measurement value fluctuates, the apparatus further includes a sampling time adjustment unit 43h that shortens the sampling time of the signals from the sensors 41 and 42 as compared to before the measurement value fluctuation, and thus a vibration waveform generated within a minute time. Can be measured appropriately.

  Next, a second embodiment of the present invention will be described. In the second embodiment, the gas meter 40 is the same as that of the first embodiment, but the configuration and processing are partially different. Hereinafter, differences from the first embodiment will be described.

  FIG. 12 is a configuration diagram showing details of the gas meter 40 according to the second embodiment. As shown in FIG. 12, in the second embodiment, the storage unit 43e includes a first storage unit (first storage unit) 43e1 and a second storage unit (second storage unit) 43e2.

  The 1st memory | storage part 43e1 memorize | stores beforehand the continuous NCC data of the measured value in case each gas appliance 10 is used, and the gas leak vibration waveform produced | generated by the production | generation part 43b. That is, the 1st memory | storage part 43e1 has memorize | stored the continuous NCC data for every gas appliance similarly to the memory | storage part 43e1 shown in 1st Embodiment.

  The second storage unit 43e2 stores in advance continuous NCC data of a measured value when it is assumed that there is a gas leak and a gas leak vibration waveform generated by the generation unit 43b. That is, the second storage unit 43e2 stores continuous NCC data at the time of gas leakage that was not stored in the first embodiment.

  Since it is such a structure, the determination part 43d determines the gas leak 10 and the used gas appliance 10 as follows. First, when the waveform of the signal from the sensors 41 and 42 is input to the input unit 41a, the generation unit 43b generates a gas leakage vibration waveform, and the similarity transition calculation unit 43c calculates a continuous NCC. Next, the determination unit 43d identifies the closest NCC data calculated by the similarity transition calculation unit 43c among the continuous NCC data stored in the first and second storage units 43e1 and 43e2.

  Then, when the closest continuous NCC data is stored in the first storage unit 43e1, the determination unit 43d determines that the gas appliance 10 indicated by the closest continuous NCC data is being used. On the other hand, the determination unit 43d determines that gas leakage has occurred when the nearest continuous NCC data is stored in the second storage unit 43e2. Thus, in 2nd Embodiment, a gas leak and the use gas appliance 10 can be determined integrally.

  Note that the correction unit 43f also functions in the second embodiment, and updates the continuous NCC data stored in the first storage unit 43e1.

  Next, the operation of the gas meter 40 according to the second embodiment will be described. FIG. 13 is a flowchart showing an example of the operation of the gas meter 40 according to the second embodiment. First, in 2nd Embodiment, operation | movement similar to step S1-S5 shown in FIG. 11 is performed in step S21-S25.

  Thereafter, in step S26, the determination unit 43d determines whether or not the continuous NCC data closest to the continuous NCC calculated in step S25 is stored in the second storage unit 43e2, that is, a gas leak (S26). . If it is determined that the gas is leaking (S26: YES), the determination unit 43d determines that a gas leak has occurred (S27). Then, the post-processing unit 43g issues an alarm or closes the shut-off valve (S28). Thereafter, the process shown in FIG. 13 ends.

  On the other hand, when determining that the nearest continuous NCC data is not a gas leak (S26: NO), the determination unit 43d determines that the gas appliance 10 indicated by the nearest continuous NCC data is being used (S29). Thereafter, in steps S30 and S31, processing similar to that in steps S10 and S11 shown in FIG. 11 is executed.

  Thereafter, the post-processing unit 43g executes a security process such as monitoring the continuous use time for the gas appliance 10 being used, or discounts a charge based on the gas usage of the gas appliance 10 being used ( S32). Then, the process shown in FIG. 13 ends.

  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.

  Further, in the present embodiment, the gas leak determination device is the gas meter 40, but is not limited thereto, and the gas leak determination device may be configured separately from the gas meter 40.

  Furthermore, although the similarity transition is calculated by the formula (1) in the above embodiment, the present invention is not limited to this, and the similarity transition may be calculated by another method.

  Furthermore, in this embodiment, the sampling time adjustment unit 43h may shorten the sampling time in advance so that the pressure and flow rate can be accurately measured immediately after the pressure and flow rate change, and the pressure and flow rate change can be quickly performed. Another configuration that can be detected may be added.

  In addition, when there is no continuous NCC data calculated by the similarity transition calculation unit 43c among the continuous NCC data stored in the storage unit 43e, the determination unit 43d stores the continuous NCC data stored in the storage unit 43e. It may be determined that the gas appliance 10 indicated by is lacking.

  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.

  Moreover, in this embodiment, based on the gas leak vibration waveform in the minute time within 1 second, the gas leak and the gas appliance 10 to be used are judged. In particular, in this embodiment, the time for measuring the pressure and the flow rate is sufficient within one second, but it may be measured for a time longer than one second in advance.

  In the present embodiment, the storage unit 43e (including the first storage unit 43e1) stores continuous NCC data for each gas appliance 10. Only one piece of this continuous NCC data may be stored for one gas appliance 10, or a plurality of pieces may be stored for one gas appliance 10.

  FIG. 14 is a graph showing corrected continuous NCC data of a water heater. In FIG. 14, the solid line indicates corrected continuous NCC data when used when the water temperature in the water heater is low to some extent, and the broken line indicates corrected continuous when used when the water temperature in the water heater is high to some extent. NCC data is shown, and the alternate long and short dash line shows corrected continuous NCC data when the water temperature in the water heater is high.

  As shown in FIG. 14, in a water heater, the continuous NCC varies depending on the water temperature in the water heater. In this case, if there is only one piece of continuous NCC data stored in the storage unit 43e (including the first storage unit 43e1), there is a possibility that the use gas appliance 10 may be erroneously determined according to the water temperature of the water heater. is there. Therefore, it is desirable to store a plurality of continuous NCC data for such a gas appliance 10. This is because the gas appliance 10 to be used can be determined with higher accuracy.

DESCRIPTION OF SYMBOLS 1 ... Gas supply system 10 ... Gas appliance 20 ... Regulator 31 ... 1st piping 32 ... 2nd piping 40 ... Gas meter (gas leak judgment apparatus)
41 ... Pressure sensor 42 ... Flow rate sensor 43 ... Control unit 43a ... Input unit (input means)
43b ... Generation unit (generation means)
43c ... Similarity transition calculation unit (similarity transition calculation means)
43d: Determination unit (determination means)
43e ... Storage section (storage means)
43e1 ... 1st memory | storage part (1st memory | storage means)
43e2 ... 2nd memory | storage part (2nd memory | storage means)
43f ... Correction unit (correction means)
43g ... post-processing unit 43h ... sampling time adjusting unit (sampling time adjusting means)

Claims (12)

A signal is input from at least one of a pressure sensor that outputs a measurement value signal corresponding to the gas pressure in the flow path and a flow rate sensor that outputs a measurement value signal corresponding to the gas flow rate in the flow path. Input means;
Generating means for generating a gas leakage vibration waveform when gas leakage is assumed;
Similarity transition calculation means for calculating a similarity transition between the waveform of the signal from the measurement sensor input by the input means and the gas leakage vibration waveform generated by the generation means;
Determination means for determining the occurrence of gas leakage based on the similarity transition calculated by the similarity transition calculation means;
A gas leak judgment device comprising: The gas leak vibration waveform generated by the generation unit is generated based on a second-order delay step response equation including a frequency, a gain, and a damping ratio of a damped vibration. Gas leak judgment device. The gas leak judgment device according to claim 2, wherein the frequency of the damped vibration is calculated from an expression including only a measured value as a variable. The gas leakage judgment device according to claim 2, wherein the attenuation ratio is calculated from an expression that includes only a measured value as a variable. In the second-order lag step response equation, the gain is K, the first extreme value in the waveform of the signal from the measurement sensor is V1, the second extreme value is M, and the third extreme value is V2. In this case, the gain K is calculated from an arithmetic expression of K = (V1 + 2M + V2) / 4. When the attenuation ratio is ζ and the number of periods from the first extreme value V1 to the second extreme value M is m in the second-order delay step response equation, the attenuation ratio ζ is δ = [(1 / m 6) The gas leak judgment device according to claim 5, wherein the gas leak judgment device is calculated from an arithmetic expression of Ln {(V1−K) / (M−K)}] / 2π. A storage means for preliminarily storing similarity transition data between the measured value when each gas appliance is used and the gas leakage vibration waveform generated by the generating means;
If the determination means determines that no gas leak has occurred based on the similarity transition calculated by the similarity transition calculation means, the determination means determines that one of the gas appliances has been used, and the storage means It is judged that the gas appliance which the similarity transition data nearest to the calculated similarity transition is used among the stored similarity transition data is used. The gas leak judgment apparatus as described in. Correction means for calculating a corrected similarity transition by subtracting the average value of the entire similarity transition from each similarity calculated by the similarity transition calculating means;
The gas leak determination device according to claim 7, wherein the storage unit updates the similarity transition data stored in advance based on the corrected similarity transition corrected by the correction unit. A first storage means that stores in advance similarity transition data between a measured value when each gas appliance is used and a gas leakage vibration waveform generated by the generating means;
A second storage means for preliminarily storing similarity transition data between a measured value when it is assumed that there is a gas leak and a gas leakage vibration waveform generated by the generating means;
The determination means includes similarity transition data in which the similarity transition data closest to the calculated similarity transition is stored in the second storage means among the similarity transition data stored in the first and second storage means. If it is data, it is determined that a gas leak has occurred, and if the closest similarity transition data is the similarity transition data stored in the first storage means, the gas appliance indicated by the similarity transition data It is judged that is used. The gas leak judgment device according to any one of claims 1 to 6 characterized by things. Correction means for calculating a corrected similarity transition by subtracting the average value of the entire similarity transition from each similarity calculated by the similarity transition calculating means;
The gas leak judgment device according to claim 9, wherein the second storage unit updates the similarity transition data stored in advance based on the corrected similarity transition corrected by the correction unit. Sampling time adjustment means for shortening the sampling time of the signal from the measurement sensor when it is determined that the measurement value has changed based on the measurement value signal input by the input means than before the measurement value change. The gas leak judgment device according to any one of claims 1 to 10, further comprising: A signal is input from at least one of a pressure sensor that outputs a measurement value signal corresponding to the gas pressure in the flow path and a flow rate sensor that outputs a measurement value signal corresponding to the gas flow rate in the flow path. Input process;
A generation process for generating a gas leak vibration waveform when it is assumed that the gas leak;
A similarity transition calculation step of calculating a similarity transition between the waveform of the signal from the measurement sensor input by the input means and the gas leakage vibration waveform generated in the generation step;
A determination step of determining occurrence of gas leakage based on the similarity transition calculated in the similarity transition calculation step;
A gas leak judgment method characterized by comprising: