JP2010139111A - Determination device and determination method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a determination device and a determination method capable of preventing the deterioration of accuracy in determination, in determining the use of a gas appliance and gas leakage. <P>SOLUTION: A gas meter 40 generates a correction waveform by differentiating a pressure waveform based on a pressure value of each time by a correction waveform generating section 47c, or generates the correction waveform by eliminating a component smaller than a prescribed frequency of the pressure waveform. A determining section 47b determines the use of a gas appliance or gas leakage from the correction waveform generated by the correction waveform generating section 47c. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

Conventionally, a gas supply system for supplying fuel gas to a gas appliance via a gas meter is known. In this gas supply system, a pressure regulating valve is installed at the outlet of the gas supply container. The pressure regulating valve functions to keep the downstream pressure at a constant value of about 2.9 kPa, for example (see, for example, Patent Document 1).
JP 2001-188020 A

  Here, the present applicant has invented the technique of Japanese Patent Application No. 2008-86022. In the present invention, based on the gas pressure, it is determined whether a gas appliance with a governor is used, a gas appliance without a governor is used, and whether a gas leak has occurred.

  However, in the gas supply system described in Patent Document 1, the gas pressure in the gas pipe rises due to temperature changes during the day and at night. That is, if the gas is left unused in the daytime, the temperature in the gas pipe rises and the pressure in the gas pipe from the pressure regulating valve to the gas appliance rises. The pressure rises by about 1 kPa when the temperature rises by about 3 ° C. during the day, and in some cases, the pressure in the gas pipe may reach 4 kPa. And if the gas pressure in a gas pipe rises, when judging whether or not a gas appliance with a governor is used based on the gas pressure as in the technique of Japanese Patent Application No. 2008-86022, the judgment accuracy decreases. I will invite you. In this specification, a part of the technology of Japanese Patent Application No. 2008-86022 is described. However, this description does not recognize the publicity of the technology of Japanese Patent Application No. 2008-86022.

  The present invention has been made to solve such a conventional problem, and the object of the present invention is to make a judgment that can prevent a reduction in judgment accuracy when judging the use of gas appliances or judging gas leaks. It is to provide an apparatus and a determination method.

  The determination device of the present invention is a determination device that determines use of a gas appliance and gas leakage from a pressure waveform based on a detected pressure value at each time, and generates a correction waveform by differentiating the pressure waveform, or Correction waveform generation means for generating a correction waveform by removing components below a predetermined frequency from the pressure waveform, and determination means for determining use of gas appliances and gas leakage from the correction waveform generated by the correction waveform generation means, It is characterized by providing.

  According to this determination device, a pressure waveform is differentiated to generate a correction waveform, or a component having a predetermined frequency or less is removed from the pressure waveform to generate a correction waveform. Determine for gas leaks. Here, when a gas appliance is used or a gas leak occurs, the pressure value decreases from the original pressure to a certain stable pressure. There is a difference in the decreasing component between when the pressure in the pipe is rising and when it is not. In particular, this decreasing component shows a gradual decrease. For this reason, by differentiating the pressure waveform, it is possible to remove the decreasing component that shows a gradual decrease, and cancel the decreasing component that differs between when the pressure in the pipe is rising and when it is not It becomes. As a result, the correction waveform can be similar between when the pressure in the gas pipe is rising and when it is not. Similarly, since the decreasing component shows a gradual decrease, the frequency becomes low. Therefore, by removing the component below the predetermined frequency from the pressure waveform, the correction waveform similarly increases the pressure in the gas pipe. It can be similar between when it is and when it is not. Therefore, it is difficult to be influenced by the lowering component in determining whether to use the gas appliance or determining a gas leak, and it is possible to prevent a decrease in determination accuracy.

  In the determination apparatus of the present invention, the correction waveform generation means differentiates the pressure waveform, obtains a moving average of values at each time of the waveform obtained by differentiation, and calculates a correction waveform from the obtained moving average value. It is preferable to produce.

  According to this determination apparatus, since the moving average of values at each time of the waveform obtained by differentiation is obtained, and the correction waveform is generated from the obtained moving average value, noise can be suppressed, and the appropriate correction waveform can be obtained. Can be achieved.

  In the determination device of the present invention, it is preferable that the correction waveform generation means is configured as a peripheral circuit of the microcomputer.

  According to this determination apparatus, since the correction waveform generating means is configured as a peripheral circuit of the microcomputer, the power consumption can be reduced without operating the microcomputer when generating the correction waveform.

  In the determination device of the present invention, it is preferable that the correction waveform generation means is constituted by a band pass filter circuit.

  According to this determination apparatus, since the correction waveform generation means is configured by a band-pass filter circuit, high-frequency noise can be cut and the correction waveform can be optimized.

  The determination method of the present invention is a determination method for determining use of a gas appliance and gas leakage from a pressure waveform based on a detected pressure value at each time, and generating a correction waveform by differentiating the pressure waveform. Or a correction waveform generation step for generating a correction waveform by removing components below a predetermined frequency from the pressure waveform, and a determination step for determining use of gas appliances and gas leakage from the correction waveform generated by the correction waveform generation step; Are preferably provided.

  According to this determination method, a pressure waveform is differentiated to generate a correction waveform, or a component having a predetermined frequency or less is removed from the pressure waveform to generate a correction waveform. Determine for gas leaks. Here, when a gas appliance is used or a gas leak occurs, the pressure value decreases from the original pressure to a certain stable pressure. There is a difference in the decreasing component between when the pressure in the pipe is rising and when it is not. In particular, this decreasing component shows a gradual decrease. For this reason, by differentiating the pressure waveform, it is possible to remove the decreasing component that shows a gradual decrease, and cancel the decreasing component that differs between when the pressure in the pipe is rising and when it is not It becomes. As a result, the correction waveform can be similar between when the pressure in the gas pipe is rising and when it is not. Similarly, since the decreasing component shows a gradual decrease, the frequency becomes low. Therefore, by removing the component below the predetermined frequency from the pressure waveform, the correction waveform similarly increases the pressure in the gas pipe. It can be similar between when it is and when it is not. Therefore, it is difficult to be influenced by the lowering component in determining whether to use the gas appliance or determining a gas leak, and it is possible to prevent a decrease in determination accuracy.

  According to the present invention, it is possible to provide a determination device and a determination method capable of preventing a decrease in determination accuracy in determining whether to use a gas appliance or determining a gas leak.

  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 determination device according to an embodiment of the present invention. The gas supply system 1 supplies fuel gas to each gas appliance 10 such as a stove, a fan heater, a water heater, and a gas stove. The gas supply system 1 includes a plurality of gas appliances 10, a gas supply source regulator 20, and a pipe 31. , 32 and a gas meter (determination device) 40. In the example illustrated in FIG. 1, the gas meter 40 is described as an example of the determination device, but the 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 adjuster 20 has a configuration in which, for example, the fuel gas is adjusted to a pressure of about 2.9 kPa and flows 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.

  The gas appliance 10 generally includes a shut-off valve 12, a governor 13, and a burner 14. The shut-off valve 12 is a valve provided in the gas appliance 10. The governor 13 has a governor inner valve 13a, and adjusts the pressure of the gas supplied to the burner 14 of the gas appliance 10 by the opening degree of the governor inner valve 13a. The pressure-adjusted fuel gas reaches the burner 14 through the nozzle 13b at the tip of the governor 13 and burns. Note that not all the gas appliances 10 have the governor 13, and some gas appliances 10 do not have the governor 13 such as a gas stove.

  FIG. 2 is a side sectional view showing an example of the governor 13 shown in FIG. In addition, in FIG. 2, only an example of the governor 13 is shown, and the configuration of the governor 13 is not limited to that shown in FIG. Further, the governor 13 shown in FIG. 2 is illustrated with the nozzle 13b shown in FIG. 1 omitted.

  As shown in FIG. 2, the governor 13 uses a part of the internal space formed by the outer wall 13c and the governor cap 13d as a gas flow path. Such a governor 13 includes a diaphragm 13e, an adjustment spring 13f, and an adjustment screw 13g in the internal space in addition to the governor inner valve 13a.

  The diaphragm 13 e is a film-like member that partitions the internal space of the governor 13. A governor inner valve 13a is attached to the diaphragm 13e on one side (flow channel side). Further, an adjustment spring 13f is attached to the other side (side not functioning as a flow path) of the diaphragm 13e. The adjustment spring 13f has a diaphragm 13e attached to one end and an adjustment screw 13g attached to the other end. The adjustment screw 13g is structured to be fixed to the inner wall of the governor 13 in which the thread groove is formed, and the compression rate of the adjustment spring 13f can be changed by changing the fixing position with the thread groove. Further, the adjusting screw 13g is not exposed to the outside, and has a structure covered with a governor cap 13d.

  The outer wall 13c of the governor 13 is formed with an air hole 13h that communicates with the other side of the diaphragm 13e. For this reason, the other side of the diaphragm 13e is air pressure. Further, in the example shown in FIG. 2, the governor inner valve 13a has a hemispherical shape, and the opening ratio of the passage port 13i can be controlled by vertical movement.

  In such a governor 13, when the gas pressure on the gas inlet side increases, the diaphragm 13e is pushed up, and at the same time, the governor inner valve 13a attached to the diaphragm 13e is also raised. Thereby, the opening ratio of the passage port 13i becomes small, and the gas flow rate decreases. On the other hand, when the gas pressure on the gas inlet side is lowered, the diaphragm 13e is lowered, and at the same time, the governor inner valve 13a attached to the diaphragm 13e is also lowered. Thereby, the opening ratio of the passage port 13i increases, and the gas flow rate increases. In this manner, the governor 13 adjusts the downstream pressure by keeping the downstream flow rate constant with respect to the upstream pressure fluctuation.

  FIG. 3 is a configuration diagram of the gas meter 40 according to the embodiment of the present invention. As shown in the figure, the gas meter 40 according to this embodiment includes a flow sensor 41, a pressure sensor 42, and a microcomputer 47.

  The flow sensor 41 is installed in the flow path in the gas meter 40 and detects the gas flow rate in the flow path. When the gas meter 40 according to the present embodiment is an ultrasonic type gas meter, the flow sensor 41 is configured by two acoustic transducers composed of, for example, piezoelectric vibrators arranged at a predetermined distance in the flow path. When the gas meter 40 according to the present embodiment is a gas meter equipped with a thermal sensor such as a flow sensor, the gas meter 40 includes a heater that generates a temperature distribution and a thermopile that generates a signal corresponding to the temperature distribution.

  The pressure sensor 42 is for detecting the gas pressure of the gas present in the flow path in the gas meter 40. The pressure sensor 42 is not limited to the flow path in the gas meter 40, and may be installed in the first pipe 31 or the second pipe 32 existing outside the gas meter 40 if possible. Similarly, the installation location of the flow sensor 41 can be changed.

  In this embodiment, the signals from the flow sensor 41 and the pressure sensor 42 are directly input to the microcomputer 47 in FIG. 3, but other elements such as an amplifier may be added between the two depending on circumstances. .

  The microcomputer 47 controls the entire gas meter 40 and performs flow rate integration control, display control, cutoff valve cutoff control, and the like. In the present embodiment, the microcomputer 47 includes a storage unit 47a and a determination unit (determination unit) 47b. The memory | storage part 47a memorize | stores the pressure value of each time detected through the pressure sensor 42. FIG. The pressure value stored in the storage unit 47a is, for example, data of about 1 second at the maximum, and is data measured at a measurement interval of about once every 1 millisecond. A pressure waveform is obtained by accumulating pressure values at each time. The determination unit 47b determines use of the gas appliance 10 and gas leakage from the pressure waveform based on the pressure value at each time.

  Here, the determination principle of the use of the gas appliance 10 and the gas leakage by the determination unit 47b will be described. FIG. 4 is a graph showing the pressure change when the use of the gas appliance 10 with the governor is started. In FIG. 4, the vertical axis represents the pressure change amount (kPa), and the horizontal axis represents the elapsed time (seconds) after the use of the governor-equipped gas appliance 10 is started.

  When the use of the gas appliance 10 with the governor is started, the pressure becomes a stable state after showing the predetermined amplitude shown in FIG. Specifically, immediately after the start of use of the gas appliance 10 with the governor, after showing a pressure drop to just “−0.1” kPa (see symbol a1), the pressure rises to about “0.05” kPa. (See symbol a2). After that, the pressure shows a pressure drop to about “−0.05” kPa (see symbol a3), and then shows a pressure rise to about “0.05” kPa (see symbol a4). Thereafter, the pressure repeatedly oscillates while the amplitude gradually decreases, and finally becomes a stable state in which there is no pressure change.

  The reason why such pressure vibration occurs is that an adjustment spring 13 f is provided in the governor 13. That is, when the use of the gas appliance 10 with the governor is started, the adjustment spring 13f vibrates, the governor inner valve 13a also vibrates, and the opening ratio of the passage port 13i changes gradually and gradually. Because it does.

  In particular, at the start of use of the gas appliance 10 with a governor, characteristics are seen in the frequency and amplitude of pressure vibration. Specifically, since the adjustment spring 13f vibrates in small increments, the pressure shows fine vibration. As a result, the pressure waveform contains many relatively high frequency components. Moreover, since the passage opening 13i becomes larger or smaller due to the vibration of the adjustment spring 13f at the start of use of the gas appliance 10 with a governor, the pressure waveform shows a large amplitude.

なる演算式で表すことができる。ここで、Ｃは振幅を示し、ｋは摩擦力（減衰定数）を示し、ωは復元力を示し、αは初期位置を示している。この式は多くの周波数ｆ_ｉ＝ω_ｉ／２πの振動の重ね合わせであることを示している。 The pressure P is

It can be expressed by the following equation. Here, C represents the amplitude, k represents the frictional force (attenuation constant), ω represents the restoring force, and α represents the initial position. This equation indicates that this is a superposition of vibrations of many frequencies f _i = ω _i / 2π.

  FIG. 5 is a graph showing the pressure change when the use of the governorless gas appliance 10 is started. In FIG. 5, the vertical axis represents the pressure change amount (kPa), and the horizontal axis represents the elapsed time (seconds) since the use of the governorless gas appliance 10 was started.

  When the use of the governorless gas appliance 10 is started, the pressure is in a stable state after showing the predetermined amplitude shown in FIG. Specifically, immediately after the start of use of the gas appliance 10 with the governor, after showing a pressure drop to “−0.1” kPa (see b1), the pressure rises to about “0.01” kPa. (See symbol b2). Thereafter, the pressure shows a pressure drop to about “−0.05” kPa (see symbol b3). Thereafter, the pressure repeatedly vibrates with no pressure increase. Then, the amplitude gradually decreases, and finally a stable state in which there is no pressure change is obtained. The reason why such pressure vibration occurs is as follows.

  FIG. 6 is a schematic diagram showing a state of supply of fuel gas in the governorless gas appliance 10. As shown in FIG. 6, when the governorless gas appliance 10 is used, the fuel gas reaches the burner 14 and the like from the second pipe 32 through the nozzle holder 100. Here, when a gas having a flow velocity flows into the nozzle holder 100, the flow rate does not decrease suddenly due to the inertial force, but the gas is compressed and the pressure rises. Thereafter, the inflow flow velocity becomes small (in some cases, a reverse flow) due to the increased pressure, and the pressure decreases. By repeating this, vibration of compression and expansion occurs.

  As described above, the pressure oscillates when the gas appliance with governor 10 is used and when the gas appliance 10 without governor is used. However, when the pressure waveform shown in FIG. 5 is compared with the pressure waveform shown in FIG. 4, there are the following differences.

  First, the governor-equipped gas appliance 10 has a substance that vibrates finely like the adjustment spring 13f, whereas the governor-less gas appliance 10 does not have such a substance. Therefore, although the pressure waveform shown in FIG. 5 shows vibration in the same manner as the pressure waveform shown in FIG. 4, the vibration frequency as a whole is lower than the pressure waveform shown in FIG.

  Further, in the case of the gas appliance 10 with the governor, the amplitude is increased by the vibration of the adjustment spring 13f. However, in the case of the gas appliance 10 with the governor, there is no adjustment spring 13f, and vibration due to the compressibility of the nozzle holder 100 occurs. There is only. For this reason, the pressure waveform shown in FIG. 5 has a smaller amplitude than the pressure waveform shown in FIG.

  From such characteristics, the determination unit 47b of the microcomputer 47 can determine whether the gas appliance with governor 10 is used or whether the gas appliance 10 without governor is used.

  FIG. 7 is a graph showing a state of pressure change at the time of gas leakage. In FIG. 7, the vertical axis represents the pressure change amount (kPa), and the horizontal axis represents the elapsed time (seconds) after the gas leak occurred.

  As shown in FIG. 7, when a gas leak occurs, the pressure gradually decreases without showing a clear vibration. Thus, in the case of gas leakage, neither the vibration of the adjustment spring 13f nor the vibration due to the compressibility of the nozzle holder 100 occurs, so no clear vibration is seen in the pressure waveform.

  As described above, there is a characteristic difference in the pressure waveform between the start of use of the gas appliance 10 with governor, the start of use of the gas appliance 10 without governor, and the occurrence of gas leakage. This feature appears within a few seconds (for example, 1 second) from the start of pressure fluctuation. The determination unit 47b of the microcomputer 47 can determine whether the gas appliance 10 with the governor is used, the gas appliance 10 without the governor, or the gas leak from the above characteristics.

  However, if the gas is left unused in the daytime, the temperature in the pipes 31 and 32 will rise, and the pressure in the pipes 31 and 32 from the regulator 20 to the gas appliance 10 will rise. The pressure rises by about 1 kPa when the temperature rises by about 3 ° C. during the day, and in some cases, the pressure in the pipes 31 and 32 may reach 4 kPa. When the gas pressure in the pipes 31 and 32 rises, as described with reference to FIGS. 4 to 7, it is determined whether or not a gas appliance with a governor is used based on the gas pressure. In addition, the accuracy of judgment is reduced.

  Here, in the following description, the pressure in the pipes 31 and 32 before the pressure fluctuation, such as before using the gas appliance or before the occurrence of gas leakage, is referred to as a source pressure.

  FIG. 8 is a graph showing pressure waveforms at the start of use of the gas appliance 10 when the source pressure is rising and when it is not rising. When the original pressure is not increased, the pressure value before the start of use of the gas appliance 10 is about 2.95 kPa. When the gas appliance 10 is used, the pressure value becomes about 2.8 kPa after 1 second while showing a predetermined vibration from the start of use. On the other hand, when the original pressure has increased, the pressure value before the start of using the gas appliance 10 is about 3.17 kPa. When the gas appliance 10 is used, the pressure value becomes about 2.8 kPa after 1 second while showing a predetermined vibration from the start of use.

  Thus, the pressure waveform obtained differs between when the source pressure is rising and when it is not rising. From such a difference, when the determination unit 47b determines whether or not the gas appliance with the governor is used, there is a possibility that the determination is erroneous.

  Therefore, in the gas meter 40 according to the present embodiment, the correction waveform is generated by correcting the pressure waveform. FIG. 3 will be referred to again. As shown in FIG. 3, the microcomputer 47 includes a correction waveform generation unit (correction waveform generation means) 47 c as a configuration for correcting the pressure waveform.

  Here, when the gas appliance 10 is used, the applicant of the present application has a pressure waveform in a section until the pressure value is stabilized (for example, a section from time “0” to “0.2” in FIG. 8). The present inventors have found that a lowering component that decreases at a certain rate and a specific component are included. The specific component is a fine vibration component when the gas appliance 10 is used, and a component that cannot be clearly described as vibration when a gas leak occurs. Furthermore, the present applicant has found that there is no significant difference in the specific component, although the decrease component differs depending on whether the source pressure is rising or not. Therefore, in the gas meter 40 according to the present embodiment, the correction waveform generation unit 47c removes the lower component and leaves the specific component, so that the same correction waveform is obtained when the original pressure increases and when the original pressure does not increase. As a result, the judgment accuracy is not lowered.

  FIG. 3 will be referred to again. The correction waveform generation unit 47c executes differentiation processing for differentiating the pressure waveform. The above-described lowering component is a component that does not vibrate and exhibits a gradual decrease. For this reason, by differentiating the pressure waveform, it is possible to remove a decreasing component that shows a gradual decrease, and it is possible to cancel a decreasing component that is different between when the original pressure is rising and when it is not. Because.

  FIG. 9 is a graph showing correction waveforms when the source pressure is rising and when it is not rising. As shown in FIG. 9, the correction waveform has a substantially similar waveform by removing the decrease component. That is, even if the original pressure is increased, the increased amount is canceled and the correction waveform is approximately similar. In the present embodiment, the determination unit 47b performs the determination as described with reference to FIGS. 4 to 7 based on the correction waveform as illustrated in FIG. 9, and whether or not the gas appliance 10 with the governor is used. Then, it is determined whether or not the gas appliance 10 without a ganaba is used and whether or not a gas leak has occurred.

  Here, the correction waveform generation unit 47c not only differentiates the pressure waveform, but also obtains a moving average of values at each time of the waveform obtained by differentiation, and generates a correction waveform from the obtained moving average value. Is desirable. This is because by obtaining the moving average, noise can be suppressed and the correction waveform can be optimized. In addition, the differential value shown on the vertical axis | shaft of FIG. 9 is the result which showed the moving average value for 15 times.

  Further, the correction waveform generation unit 47 c may be configured as a peripheral circuit of the microcomputer 47. In particular, the correction waveform generation unit 47c is preferably a differentiation circuit capable of continuously differentiating an analog voltage signal. By using an analog differentiating circuit, the correction waveform generation unit 47c is not required in the microcomputer 47, the calculation processing of the microcomputer 47 is reduced, and the power consumption by the microcomputer 47 can be reduced. Moreover, it is because the time of arithmetic processing can be shortened. Furthermore, it is possible to immediately execute a discrimination process (for example, step S13 described later) and a security process (for example, step S15 described later) accompanying the determination process. In addition, if an analog differentiating circuit is used, a correction waveform can be obtained without amplifying noise due to A / D conversion that would be amplified in the differential operation processing, so that smoothing operation processing such as moving average is not performed. The power consumption can be reduced accordingly.

  In analog differentiation circuits, it is difficult to have differential characteristics up to a high frequency, and components above a predetermined frequency are removed, but high frequency components are judged to be noise for gas leak / gas appliance discrimination. Convenient.

  Further, the correction waveform generation unit 47c may be configured by a high-pass filter circuit or a band-pass filter circuit that removes a component having a predetermined frequency or less from the pressure waveform. This is because the above-described lower component shows a gradual decrease, and therefore the frequency becomes lower. Therefore, the same effect as in the case of differentiation can be obtained by removing a component having a predetermined frequency or less from the pressure waveform.

  When a high-pass filter circuit is used, the cutoff frequency is preferably several to several tens Hz. When a band-pass filter circuit is used, the low-frequency side cutoff frequency is preferably several to several tens Hz, and the high-frequency side is The cut-off frequency is desirably about 500 Hz.

  Next, the use of the gas appliance 10 in the gas meter 40 according to the present embodiment and a method for determining gas leakage will be described with reference to flowcharts. FIG. 10 is a flowchart showing a determination method of the gas meter 40 according to the present embodiment.

  As shown in FIG. 10, first, the storage unit 47a of the microcomputer 47 stores the pressure value detected through the pressure sensor 42 (S10). Next, the microcomputer 47 determines whether or not the measurement is finished (S11). The measurement time is several seconds (for example, 1 to 2 seconds), and the microcomputer 47 determines whether or not the several seconds have passed. When it is determined that the measurement is not finished (S11: NO), the process proceeds to step S10, and the storage unit 47a stores the pressure value detected through the pressure sensor 42 (S10).

  On the other hand, when it is determined that the measurement is finished (S11: YES), the correction waveform generation unit 47c generates a correction waveform (S12). As described above, the correction waveform is generated by differentiation processing or the like, and is obtained by reducing or eliminating the influence of the lower component as shown in FIG. Thereafter, the determination unit 47b determines use of the gas appliance 10 or gas leakage based on the correction waveform (S13). Thereafter, the microcomputer 47 determines whether or not there is no gas leakage in the process of step S16 (S14).

  If it is determined that there is no gas leak (S14: YES), the process shown in FIG. 10 ends. On the other hand, if it is not determined that there is no gas leak (S14: NO), that is, if it is determined that there is a gas leak, the microcomputer 47 shuts off the shutoff valve and issues an alarm (S15). Thereafter, the process shown in FIG. 10 ends.

  When the correction waveform generation unit 47c is configured by a peripheral circuit of the microcomputer 47, the waveform based on the pressure value stored in step S10 becomes the correction waveform as it is, so step S12 is not performed and the gas appliance in step S13 is immediately performed. Judgment processing is performed to judge the use and gas leakage.

  FIG. 11 is a flowchart showing details of step S13 shown in FIG. 10, and shows processing related to use of the gas appliance 10 and determination of gas leakage. As shown in FIG. 11, first, the microcomputer 47 analyzes the frequency of the correction waveform generated in step S12 of FIG. 10 (S30) and the amplitude (S31).

  Thereafter, the microcomputer 47 determines whether or not a frequency component equal to or higher than the discriminant value is included in the waveform based on the analysis result of step S30 (S32). If it is determined that a frequency component equal to or higher than the discriminant value is included (S32: YES), that is, if the frequency is high to some extent as in the pressure waveform shown in FIG. 4, the microcomputer 47 uses the gas appliance 10 with the governor. (S33). Then, the process illustrated in FIG. 11 ends, and the process proceeds to step S14 in FIG.

  If it is determined that the frequency component equal to or greater than the discriminant value is not included in the specified value or more (S32: NO), the microcomputer 47 determines that the amplitude value of the first peak (that is, the amplitude is positive first after the pressure changes) Is the value obtained by adding a predetermined amount to the original pressure (pressure of “0” on the vertical axis in FIG. 4). It is determined whether or not this is the case (S34). If it is determined that the amplitude value of the first peak is equal to or greater than a value obtained by adding a predetermined amount to the original pressure (S34: YES), the microcomputer 47 determines that the gas appliance 10 with the governor is used (S33). Then, the process illustrated in FIG. 11 ends, and the process proceeds to step S14 in FIG.

  On the other hand, when it is determined that the amplitude value of the first mountain is not equal to or greater than the value obtained by adding a predetermined amount to the original pressure (S34: NO), the microcomputer 47 determines that the amplitude value of the first mountain is substantially equal to the original pressure. It is determined whether or not (specifically, the original pressure ± the specified value) (S35). When it is determined that the amplitude value of the first peak is substantially equal to the original pressure (S35: YES), the microcomputer 47 determines that the governorless gas appliance 10 is used (S36). Then, the process illustrated in FIG. 11 ends, and the process proceeds to step S14 in FIG.

  If it is determined that the amplitude value of the first peak is not substantially equal to the original pressure (S35: NO), the microcomputer 47 determines that the amplitude value of the first peak is equal to or less than the value obtained by subtracting a predetermined amount from the original pressure. It is determined whether or not (S37). When it is determined that the amplitude value of the first peak is equal to or less than a value obtained by subtracting a predetermined amount from the original pressure (S37: YES), the microcomputer 47 detects a flow rate that is equal to or greater than a specified amount based on a signal from the flow sensor 41. It is determined whether or not (S38).

  When it is determined that a flow rate exceeding the specified amount is detected (S38: YES), that is, the characteristics of frequency and amplitude due to the use of the gas appliance 10 cannot be obtained, the gas pressure in the flow path is reduced, and the specified amount is obtained. If the above flow rate is detected, the microcomputer 47 determines that there is a gas leak (S39). Then, the process illustrated in FIG. 11 ends, and the process proceeds to step S14 in FIG.

  By the way, when it is determined that the amplitude value of the first peak is not less than or equal to the value obtained by subtracting the predetermined amount from the original pressure (S37: NO), and when it is determined that the flow rate exceeding the specified amount is not detected (S38: NO). The microcomputer 47 determines that neither the use of the gas appliance 10 nor the gas leakage is applicable (S40). Then, the process illustrated in FIG. 11 ends, and the process proceeds to step S14 in FIG.

  Note that the use of the gas appliance 10 and gas leakage are not limited to those shown in FIG. 11, and may be determined by other methods, for example. For example, if the microcomputer 47 determines “YES” in step S32 or step S34, the microcomputer 47 determines that the gas appliance with governor 10 is used, but not limited to this, “YES” in both step S32 and step S34. If it is determined, it may be determined that the gas appliance with governor 10 is used.

  Further, the microcomputer 47 may determine that the governor-equipped gas appliance 10 is used when the attenuation coefficient of the pressure waveform is equal to or less than a predetermined value. Further, the microcomputer 47 determines that the amplitude value of the first peak is the amplitude value of the first valley (that is, the minimum value when the amplitude first increases in the negative direction after the pressure changes, When the amplitude is smaller than the value when the amplitude is increased in the negative direction, it may be determined that the gas appliance 10 with the governor is used. Furthermore, you may judge use of the gas appliance 10 with a governor combining various above-mentioned content.

  As described above, according to the gas meter 40 and the determination method according to the present embodiment, the pressure waveform is differentiated to generate a correction waveform, or the correction waveform is generated by removing a component having a predetermined frequency or less from the pressure waveform. The use of the gas appliance 10 and the gas leakage are determined from the generated correction waveform. Here, when the gas appliance 10 is used or a gas leak occurs, the pressure value decreases from the original pressure to a certain stable pressure. There is a difference in the decreasing component between when the source pressure is rising and when it is not. In particular, this decreasing component shows a gradual decrease. For this reason, by differentiating the pressure waveform, it is possible to remove the decreasing component that shows a gradual decrease, and cancel the decreasing component that differs between when the source pressure is rising and when it is not. . As a result, the correction waveform can be similar between when the pressure in the gas pipe is rising and when it is not. Similarly, since the decrease component shows a gradual decrease, the frequency becomes low. Therefore, by removing the component below the predetermined frequency from the pressure waveform, the correction waveform similarly increases the original pressure. The case can be similar to the case not. Therefore, when using the gas appliance 10 or determining the gas leakage, it is difficult to be influenced by the lowering component, and it is possible to prevent the determination accuracy from being lowered.

  In addition, since the moving average of the differentiated values at each time is obtained and a correction waveform is generated from the obtained moving average value, noise can be suppressed and the correction waveform can be optimized.

  Moreover, since the correction waveform generation unit 47c is configured as a peripheral circuit of the microcomputer 47, it is possible to reduce power consumption without operating the microcomputer 47 when generating the correction waveform.

  In addition, since the correction waveform generation unit 47c is configured by a bandpass filter circuit, high-frequency noise can be cut and the correction waveform can be optimized.

  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. For example, in the present embodiment, the pressure value is a measurement interval once per millisecond, but this is not a limitation, and the measurement interval can be changed as appropriate.

  In the present embodiment, the determination device exists as an internal configuration of the gas meter 40. However, the determination device is not limited thereto, and the determination device may be configured by being taken out from the gas meter 40.

It is a lineblock diagram of a gas supply system containing a judgment device concerning an embodiment of the present invention. FIG. 2 is a side sectional view showing an example of the governor shown in FIG. 1. It is a lineblock diagram of the gas meter concerning the embodiment of the present invention. It is a graph which shows the mode of a pressure change when the use of the gas appliance with a governor is started. It is a graph which shows the mode of a pressure change when the use of a gas appliance without a governor is started. It is the schematic which shows the mode of supply of the fuel gas in a gas appliance without a governor. It is a graph which shows the mode of the pressure change at the time of gas leak. It is a graph which shows the pressure waveform at the time of the start of use of the gas appliance in the case where the original pressure is rising and the case where it is not rising. It is a graph which shows the correction | amendment waveform in the case where the source pressure is rising and the case where it is not rising. It is a flowchart which shows the judgment method of the gas meter 40 which concerns on this embodiment. It is a flowchart which shows the detail of step S13 shown in FIG. 10, and has shown the process regarding use of a gas appliance and a gas leak determination.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gas supply system 10 ... Gas appliance 12 ... Shut-off valve 13 ... Governor 13a ... Governor inner valve 13b ... Nozzle 13c ... Outer wall 13d ... Governor cap 13e ... Diaphragm 13f ... Adjustment spring 13g ... Adjustment screw 13h ... Air hole 14 ... Burner 20 ... Adjuster 31 ... First pipe 32 ... Second pipe 40 ... Gas meter (judgment device)
41 ... Flow rate sensor 42 ... Pressure sensor 47 ... Microcomputer 47a ... Storage unit 47b ... Determination unit (determination means)
47c ... Correction waveform generation unit (correction waveform generation means)

Claims (5)

From the pressure waveform based on the detected pressure value at each time, a judgment device for judging the use of gas appliances and gas leakage,
A correction waveform generating means for differentiating the pressure waveform to generate a correction waveform, or generating a correction waveform by removing a component having a predetermined frequency or less from the pressure waveform;
A judging means for judging use of a gas appliance and gas leakage from the correction waveform generated by the correction waveform generating means;
A judgment device comprising: The correction waveform generation means differentiates the pressure waveform, calculates a moving average of values at different times of the waveform obtained by differentiation, and generates a correction waveform from the calculated moving average value. The determination apparatus according to claim 1. The determination apparatus according to claim 1, wherein the correction waveform generation unit is configured as a peripheral circuit of a microcomputer. The determination apparatus according to claim 3, wherein the correction waveform generation unit includes a band-pass filter circuit. A judgment method for judging use of a gas appliance and gas leakage from a pressure waveform based on a detected pressure value at each time,
A correction waveform generation step of generating a correction waveform by differentiating the pressure waveform, or generating a correction waveform by removing a component having a predetermined frequency or less from the pressure waveform;
A determination step of determining use of gas appliances and gas leakage from the correction waveform generated by the correction waveform generation step;
The judgment method characterized by comprising.

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