JP2920868B2 - Seismic level judgment method and gas meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining an earthquake level by classifying the magnitude of an earthquake into several classes, and a gas meter using the method.

[0002]

2. Description of the Related Art Conventionally, a seismic sensor is provided in a gas meter, a gas emergency shut-off device, a gas consuming device, and the like. When an earthquake occurs, gas is supplied to a gas consuming device provided downstream from the gas meter. It is configured to shut off the supply, thereby maintaining safety.

FIG. 15 is a configuration diagram showing an example of a typical prior art. When no earthquake has occurred, the base 1
A sphere 3 is fitted into the recess 2 of the
Is loaded. When the moving contact 5 is displaced upward by the lifting piece 4, the moving contact 5 can contact the fixed contact 6. In a state where no earthquake has occurred as shown in FIG. 15A, the moving contact 5 is not lifted by the lifting piece 4 and is therefore separated from the moving contact 5 fixed contact 6.

When the base 1 vibrates due to an earthquake, FIG.
As shown in (2), the sphere 3 protrudes from the recess 2 and rises, and the lifting piece 4 rises accordingly. Therefore, the moving contact 5 is raised by the lifting piece 4 and is electrically connected to the fixed contact 6. As a result, the contacts 5 and 6 become conductive, and it is detected that an earthquake has occurred.

A seismic sensor having the configuration shown in FIG.
For example, as shown in FIG.
(Where 1 gal = 0.001 g, g is the gravitational acceleration), the acceleration of the detected earthquake is 150 to 25.
Variations occur over a range of 0 gal. That is, in the prior art shown in FIG. 15, there is a problem that the detected acceleration varies, and therefore, a desired accurate acceleration cannot be detected.

In this prior art, the configuration is clearly large and the sensitivity is low. Further, there is a problem that the annular support end of the recess 2 into which the sphere 3 partially fits must be installed so as to lie substantially in the same horizontal plane, otherwise a malfunction may occur.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an earthquake level determination method and a gas meter capable of accurately detecting an acceleration of an earthquake and appropriately determining an earthquake level.

[0008]

[0009]

SUMMARY OF THE INVENTION The present invention relates to a method for determining an earthquake level using a seismic sensor which outputs a signal which continuously changes with respect to the acceleration of an earthquake, wherein the seismic sensor is cantilevered. A conductive pendulum that is supported, a pair of opposing electrodes that are spaced apart in the direction of vibration of the pendulum, a pair of conductive substrates that support and are electrically connected to the opposing electrodes, and A seismic sensor comprising a pair of glass layers interposed between the substrate and a capacitance detecting means for detecting a capacitance between the pendulum and each counter electrode, wherein a cutoff frequency f0 is 5 to 10 Hz. The output signal of the seismic sensor is passed through the low-pass filter set in the range, the magnitude of the output signal of the low-pass filter is divided into a plurality of discrimination levels to set a plurality of judgment regions, and the seismic continuation time and Set in advance for each judgment area Was then compared with the reference time, a seismic level determination method characterized by determining the seismic level.

The present invention also provides a gas passage for guiding a gas supplied from a gas inlet to a gas outlet, a gas measuring means for measuring a gas flow rate in the gas passage, and a gas passage for shutting off the gas passage. In a gas meter having a shutoff valve, a seismic sensor that outputs a signal that continuously changes with respect to the acceleration of an earthquake, and a cutoff frequency f0 is set in a range of 5 to 10 Hz, and a frequency of an output signal of the seismic sensor A low-pass filter for removing a frequency component higher than the cut-off frequency f0 among the components, a signal discriminating means for discriminating an output signal of the low-pass filter at a plurality of discrimination levels, and each judgment divided by an earthquake duration and a plurality of discrimination levels A duration determination unit that compares a determination reference time preset for each region,
The seismic sensor is a cantilevered conductive pendulum, a pair of opposing electrodes spaced apart in the vibration direction of the pendulum, a pair of conductive substrates that support and electrically connect the opposing electrodes, And a seismic sensor consisting of a pair of glass layers interposed between the pendulum attachment portion and the conductive substrate, and a capacitance detecting means for detecting the capacitance between the pendulum and each counter electrode, The gas meter is characterized in that the shut-off valve is operated based on each determination result of the signal discriminating means and the duration determining means.

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

According to the present invention, the cutoff frequency f0 is 5 to 10H.
By using a low-pass filter set in the range of z, a signal whose center frequency component as a seismic wave is around 2 to 5 Hz is filtered out from the output signal of the seismic device and selectively derived, for example, around 10 Hz. Since the shock wave can be cut off, an erroneous determination of the earthquake level can be prevented. In addition, the seismic sensor outputs a signal that continuously changes with respect to the acceleration of the earthquake, and divides the magnitude of the output signal into a plurality of discrimination levels to set a plurality of judgment regions, thereby enabling the seismic device to detect the earthquake. The size can be classified into several grades. Therefore, according to the magnitude of the magnitude of the earthquake, it is possible to switch the seismic operation of the gas-related equipment such as a gas meter for each rank. In addition, a judgment reference time is set in advance for each judgment area, and when a certain earthquake falls in a specific judgment area, the earthquake continuation time is compared with the judgment reference time of this judgment area to determine the earthquake. The level of the magnitude of the earthquake according to the length of the duration can be determined. Therefore, appropriate measures can be taken according to the magnitude and duration of the earthquake.

According to the gas meter of the present invention, by using a low-pass filter whose cutoff frequency f0 is set in the range of 5 to 10 Hz, the center frequency component as a seismic wave from the output signal of the seismic sensor is 2 to 5 Hz. A signal in the vicinity can be filtered out to selectively derive, for example, a shock wave in the vicinity of about 10 Hz can be cut off, so that malfunction of the shut-off valve can be prevented. In addition, the seismic sensor outputs a signal that continuously changes with respect to the acceleration of the earthquake, and the magnitude of the earthquake can be classified into several classes by discriminating the output signal at a plurality of discrimination levels. Therefore, it is possible to switch the seismic operation content for each rank according to the magnitude of the magnitude of the earthquake. Furthermore, a judgment reference time is set in advance for each judgment area divided by a plurality of discrimination levels,
When a certain earthquake falls in a specific determination area, the magnitude of the earthquake according to the length of the earthquake duration can be determined by comparing the duration of the earthquake with the determination reference time of the determination area. . Therefore, it is possible to appropriately determine whether to operate the shutoff valve in the gas passage according to the magnitude and duration of the earthquake.

[0018]

[0019]

Also, the seismic sensor comprises a cantilevered conductive pendulum and a pair of opposing electrodes spaced apart in the vibration direction of the pendulum, and a seismic sensor between the pendulum and each opposing electrode. And a capacitance detecting means for detecting the capacitance of the above, it is possible to measure the acceleration of the earthquake with high accuracy in a small and lightweight configuration.

[0021]

[0022]

[0023]

FIG. 1A is a perspective view showing a seismic sensor 10 according to the present invention. The seismic device 10 includes a block 11 such as a rectangular parallelepiped or a cube, and 3
There are provided seismic sensors S1, S2, and S3 that are fixed to the two mounting surfaces 12, 13, and 14, respectively. Block body 11
Is a rigid body made of metal such as iron or aluminum, or made of synthetic resin. Further, as shown in FIG. 1B, a cubic seismic sensor 10 may be formed by joining the seismic sensors S1, S2, and S3 themselves. The sensors S1, S2, and S3 have the same configuration, and may be collectively referred to by reference numeral S.

FIG. 2A is a sectional view of the sensor S1.
FIG. 2B is a perspective view showing the sensor S1 with a cutout. The sensor S1 is a cantilevered pendulum 15 and a direction in which the pendulum 15 reciprocates (a vertical direction in FIG. 2A).
A pair of electrodes 16, 17 arranged on both sides of the pendulum 15
And The pendulum 15 includes a pendulum main body 18 and a cantilever support portion 19, and the cantilever support portion 19 is connected to the mounting portion 20. The pendulum 15 and the mounting portion 20 are made of conductive single crystal silicon. The spacer 21 is arranged to face the pendulum main body 18. The electrodes 16 and 17 are formed on flat glass plates 22 and 23.
Reference numerals 6 and 17 denote aluminum thin films formed by, for example, a technique such as vapor deposition. The glass plates 22 and 23 are fixed to substrates 24 and 25 made of conductive single crystal silicon, respectively, and the electrodes 16 and 17 are connected to the substrates 24 and 25 through connection holes 26 and 27 formed in the glass plates 22 and 23. 25 is electrically connected. Thus, the sensor S1 is as shown in FIG.
Are configured symmetrically with respect to the symmetry plane 28 of. Since the cantilever support portion 19 is a completely elastic body, no hysteresis, brittleness and creep occur. Mounting part 20 and glass plate 2
2, 23 and the substrates 24, 25 are completely fused via silicon dioxide, as is the spacer 21, so that the internal space 29 is airtight and evacuated.
Spacing d1, d between pendulum body 18 and electrodes 16, 17
2 is about 2 to 5 μm in a natural state, that is, in a state where no acceleration is acting, and in this embodiment, d1 = d
2. The spacer 21 is made of the same material as the pendulum 15 and the mounting part 20. Thus, the sensor S1 is, for example, 2 × 2 × 3 mm in thickness and is formed in a minute shape. When the thickness direction of the pendulum 15 (the vertical direction in FIG. 2A) is the x direction, the sensor S1 is fixed to the mounting surface 12 of the block body 11 in FIG. You. The remaining sensors S2 and S3 are similarly configured.

Such a sensor S1 has stable characteristics over a long period of time, and can detect acceleration with high accuracy in a wide temperature range of -40 to + 125 ° C. Since the sensor S1 is symmetrical with respect to the surface 28 and therefore expands uniformly even by thermal expansion, the combined value of the capacitances of the pendulum body 18 and the electrodes 16 and 17 does not change. Further, the sensor S1 detects the over-impact of about 4000 g (g is the gravitational acceleration), that is, the swing of the pendulum body 18 due to the over-acceleration.
That is, since the restriction is made by the glass plates 22 and 23, an excessive bending force does not act on the cantilever support portion 19 supporting the pendulum main body 18, so that the breakage of the cantilever support portion 19 can be prevented. Further, according to the configuration of this embodiment, the selectivity in the sensitivity direction is excellent. That is, since the sensor S1 including the pendulum 15 forms a laminated structure in the vertical direction of FIG. 2A, the sensitivity is excellent in the vertical direction of FIG.
The sensitivity in the direction perpendicular to the paper of FIG. 2A is extremely low.

Further, the pendulum 15 and the mounting portion 20
Fine processing is easy due to the semiconductor etching technology, and the quality can be stabilized by reducing the number of manufacturing steps by automating the sensor S1 and the price can be reduced by the mass production effect. In addition, since the sensor S1 can be manufactured by the silicon wafer technology and has a very low temperature coefficient, it can be adjusted and shipped at room temperature, thereby greatly reducing the number of manufacturing steps. In addition, a micro-etching technique can be adopted, and miniaturization can be achieved. The remaining sensors S2 and S3 also have the same configuration as the sensor S1.

FIG. 3 is a block diagram showing an electric circuit of the vibration sensor 10 and the gas meter 50 according to the present invention. Pendulum 15 and each electrode 1 of three sensors S1, S2, S3
6 and 17 are connected to the lines 31, 32 and 33 via the mounting portion 20 and the substrates 24 and 25, respectively. When the capacitance between the pendulum 15 and each of the electrodes 16 and 17 is C1 and C2, in a natural state where no acceleration exists, C1 = C
2, when acceleration occurs, the law of inertia gives
The intervals d1 and d2 (see FIG. 2 (1)) are different from each other, whereby C1 <C2 or C1> C2. The conversion circuit 34 is connected to the lines 31, 32, 33, and outputs voltages V1, V2 corresponding to the capacitances C1, C2 of one sensor S1 to lines 35, 36, respectively.

[0028]

(Equation 1)

Here, V0 is a voltage applied by the temperature compensation circuit 37 to the conversion circuit 34 via the line 38, and performs an offset adjustment together with the offset circuit 39. The differential amplifier circuit 40 responds to the output of the lines 35 and 36, respectively, and derives the output V3 of the difference between the two voltages V1 and V2 on the line 41.

[0030]

(Equation 2)

Here, the composite value (C1-C2) / (C1 + C
2) is proportional to the acceleration of the sensor S1 in the x direction.

The above description has been made mainly with respect to only the sensor S1, but the pendulum 15 of the sensor S1 and the pendulum of the remaining sensors S2 and S3 are commonly connected to the line 31.
And the electrodes 16 and 17 are connected to the remaining sensors S
2 and S3 are connected to the lines 32 and 33 together with the corresponding electrodes. Therefore, C shown in the above-described equations 1 to 3
1, C2 can be considered as the parallel capacity of S1, S2, S3 of each of these sensors.

The signal derived from the amplifier circuit 40 on the line 41 is supplied to a low-pass filter 42.

FIG. 4 is an electric circuit diagram showing a specific configuration of the low-pass filter 42. Low-pass filter 42
Has a characteristic that a signal having a center frequency component of about 2 to 5 Hz, which is a seismic wave, is filtered and selectively derived, and has a characteristic of blocking a shock wave of about 10 Hz, for example, that is, only a seismic wave shown in FIG. And the cutoff frequency f0 is determined so as to cut off the shock wave. The low-pass filter 42 includes an operational amplifier 143, a resistor R1, and a resistor R2.
And a capacitor C10.
Is shown in

[0035]

(Equation 3)

FIG. 6 is a diagram showing the characteristics of the low-pass filter 42. Ideally, as shown in FIG. 6, the low-pass filter 42 functions to pass a signal in a frequency band lower than the cut-off frequency f0 and block the signal in a frequency band higher than the cut-off frequency f0.

FIG. 7 is a graph showing experimental results of output voltage characteristics with respect to vibration acceleration. The sensor S1 is placed on the symmetry plane 2
8 is horizontal, the output voltage at a vibration frequency of 10 Hz is measured by a vibrator in a direction perpendicular to the symmetry plane 28,
When the magnitude of the vibration at this time was 0.2 g (peak) and was constant, a characteristic line 47 was obtained. Further, when the sensor S1 is set in a posture in which the symmetry plane 28 is vertical and vibration is applied to the symmetry plane 28 in the vertical direction in the same manner as described above,
A characteristic line 48 was obtained.

Thus, even if the mounting posture of the sensor S1 changes, the discrimination level of the signal derived from the amplifier circuit 40 corresponding to the sensor S1 to the line 41 is substantially the same, and therefore the detected acceleration is , It was confirmed that it hardly depends on the mounting posture of the sensor S1. This indicates that the attachment of the sensor S1 is facilitated.

Referring again to FIG. 3, low-pass filter 4
2 is input to the AD conversion circuit 71 to be converted from an analog signal to a digital signal.
It is taken into a PU (central processing unit) 72. CPU72
Performs an earthquake level determination operation as described below, turns on the warning display lamp 62 through the drive circuit 75 based on the determination result, or performs the shut-off valve 52 through the drive circuit 76.
Close. The CPU 72 has a ROM (Read Only Memory) 73 and a RAM (Random Access Memory)
74 is connected, and stores programs and data necessary for the operation of the CPU 72.

FIG. 8 is a partially cutaway perspective view of a gas meter 50 according to an embodiment of the present invention, and FIG.
FIG. 3 is a system diagram showing a gas flow path and an electric block. When gas is supplied from the inlet 51 of the gas meter 50, the gas flows from the shut-off valve 52 through the passage 60 to the gas meter main body 53 such as a membrane gas meter, and the gas flow rate is measured. The metered gas is distributed to the gas consuming equipment from the outlet 54 through the passage 61.

A circuit board 55 is mounted on the gas meter 50, and a battery 56 that can be used for a long time, such as a lithium battery, is used as a power supply for the circuit board 55. The seismic device 10 is mounted on a circuit board 55, and the remaining electric circuits shown in FIG. CPU 7 of FIG.
When an earthquake is detected by 2, the display lamp 62 is turned on to notify the user of the occurrence of the earthquake. Also,
Depending on the level of the earthquake, the shutoff valve 52 will be closed.
Thus, gas is prevented from being supplied to the gas meter main body 53 and the gas outlet 54, and a fuel gas leak accident on the downstream side of the gas meter 50 can be prevented. When the return button is operated, the shutoff valve 52 returns to its original state, and the gas supply is restarted.

On the other hand, the gas amount detected by the gas meter main body 53 is converted into an electric signal by the flow sensor 57 and inputted to the CPU 72 mounted on the circuit board 55. In addition, it is possible to input an external signal 59 to the CPU 72 via the circuit board 55 from a gas leak alarm, an incomplete combustion alarm, or the like installed near the gas consuming device, and display the signal based on the external signal 59. Lamp 62 and shutoff valve 5
2 may be operated.

FIG. 10 is a conceptual diagram showing an earthquake level determination area, and FIG. 11 is a flowchart showing an earthquake level determination method according to the present invention. First, in FIG.
The acceleration of the earthquake corresponding to the data taken from the conversion circuit 71 into the CPU 72, that is, the vibration value is shown on the vertical axis, and is 80 gal, 100 gal, 150 gal, 25 gal.
Four discrimination levels of 0 gal are set in advance. Next, the operation contents of the judgment area will be described. 1) In the judgment area VA having a range of the vibration value of 0 to 80 gal, although the occurrence of an earthquake is detected, it is judged that it is a weak earthquake and no operation is performed. 2) In the judgment area VB having a vibration value of 80 to 100 gal, the gas cutoff and the alarm operation are performed when the earthquake continues for 30 seconds. However, the duration of the earthquake is 3
If less than 0 seconds, only the alarm operation is executed. 3) Judgment area VC having a range of vibration value 100 to 150 gal
Performs gas shutoff and alarm action if an earthquake lasts 5 seconds. However, if the duration of the earthquake is less than 5 seconds, only the alarm operation is performed. 4) Vibration value 150-2
The determination region VD having a range of 50 gal performs a gas shutoff and an alarm operation when an earthquake continues for 3 seconds.
However, if the duration of the earthquake is less than 3 seconds, only the alarm operation is performed. 5) In the determination area VE having a range of the vibration value of 250 gal or more, the determination reference time is 0 seconds, that is, the gas shutoff and the alarm operation are immediately performed.

Next, referring to FIG. 11, when the judgment criteria of FIG. 10 are specifically applied, when the CPU 72 detects the occurrence of an earthquake and starts the seismic sensing mode, first, in step a1, it is determined whether or not the vibration value is 250 or more. Is determined, and the determination area V
If E, the process proceeds to step a2, in which the shutoff valve 52 is immediately closed to shut off the gas, and at the same time, the display lamp 62 is turned on to perform an alarm operation. Therefore, step a
In 2, it can be considered that the determination reference time is 0.

On the other hand, in step a1, the vibration value is
If it does not correspond to E, the process proceeds to step a3 to start the timer and start measuring the earthquake duration time. Next, in step a4, it is determined whether or not the vibration value is 150 or more. If the vibration value is within the determination area VD, the process proceeds to step a5, and it is determined whether or not the value of the timer is 3 seconds or more. If the time has elapsed for 3 seconds or more, the process proceeds to step a6 to perform the gas shutoff and the alarm operation.
If the duration of the earthquake is less than 3 seconds, in step a7, only the alarm operation is performed without shutting down the gas, and the user is notified of the occurrence of the earthquake.

On the other hand, in step a4, the vibration value
If it does not correspond to D, the vibration value is 1 in step a8.
It is determined whether or not the time is equal to or more than 00, and if the time falls within the determination area VC, the process proceeds to step a9, where it is determined whether or not the value of the timer is 5 seconds or more. If so, the process proceeds to step a10 to perform gas shutoff and alarm operation. If the continuation time of the earthquake is less than 5 seconds, in step all, only the alarm operation is performed without shutting down the gas, and the user is notified of the occurrence of the earthquake.

On the other hand, in step a8, the vibration value
If it does not correspond to C, it is determined in step a12 whether or not the vibration value is 80 or more. If it falls in the determination area VB, the process proceeds to step a13 and the timer value is set to 30.
It is determined whether or not the time is equal to or longer than seconds. If the earthquake duration time is equal to or longer than 30 seconds, the process proceeds to step a14 to perform the gas shutoff and the alarm operation. If the duration of the earthquake is less than 30 seconds, in step a15, only the alarm operation is performed without shutting down the gas, and the user is notified of the occurrence of the earthquake.

On the other hand, if the vibration value does not correspond to the determination region VB in step a12, it corresponds to the determination region VA, and the seismic mode ends without any operation.

In the above description, 80 gal, 100 gal
Although an example using four discrimination levels of gal, 150 gal, and 250 gal and further using four judgment reference times of 0 seconds, 3 seconds, 5 seconds, and 30 seconds has been described, the present invention is limited to these numerical values and numbers. Not something.

FIG. 12 is a block diagram showing another example of the electric circuit of the gas meter 50 according to the present invention. In FIG. 12, the configuration of the seismic device 10 is the same as that described with reference to FIGS. The comparison circuit 44 compares the input signal with a predetermined discrimination level and outputs the signal to the modem 70 via the control output circuit 46.

FIG. 13A is a graph showing a temporal change of the seismic intensity, and FIG. 13B is a graph showing a frequency distribution of the seismic intensity. The seismic intensity changes with the passage of time from the occurrence of the earthquake, and the frequency distribution also changes every moment. Therefore, it is necessary to transfer a large amount of data at high speed in order to measure these changes faithfully. Therefore, in the present invention, centralized monitoring is performed by a transmission line via the modem 70.

FIG. 14 is a block diagram for explaining an example of a seismic intensity measuring method using the gas meter of FIG. Gas meters are installed at the ends of many pipelines, and the gas consumption is calculated for each user. Among them, some gas meters 50 for monitoring the magnitude of the earthquake are selected in advance.

The seismic intensity data measured by each gas meter 50 is digitized by the comparing circuit 44 of FIG. 12, and is input to the modem 70 for data transmission, and modulates the seismic intensity data by a predetermined modulation method.

Each of the modems 70 and the centralized monitoring device 74 are connected by a transmission line of a wired system, a wireless system, or a combination thereof, for example, an existing telephone line, and data transmitted by the modem 70 is collectively collected. Is done.

The centralized monitoring device 74 includes a central control device 72 such as a computer for totalizing the transmitted data and performing data storage and data analysis, and a display device 73 for displaying the data analysis result in an easily understandable manner. Is provided.

In the display device 73, gas pipelines are schematically represented on a map of a gas supply area, and are branched from, for example, a gas plant 80 to end terminals 83 via pipelines 81 and 82. At the end 83, a color light source that can be colored and lit such as red, yellow, and green is installed.

Next, the operation will be described. The seismic intensity data measured by each gas meter 50 is collected by the central control device 72 via the modem 70 every moment. The central controller 72
Each seismic intensity data is compared with a permissible range preset for each pipe end, and if it is within the permissible range, the color light source at the end 83 from which the data is obtained is lit in green. Also,
If the data exceeds the allowable range, the terminal 83 is lit in red. Further, if the data is below the allowable range, the terminal 83 is lit in yellow.

In this manner, whether or not the seismic intensity data of each gas meter 50 is allowed can be clearly displayed on the map. Therefore, when an abnormality in seismic intensity data is displayed, prompt investigation of the cause and countermeasures are possible.

[0059]

As described in detail above, according to the present invention, only a seismic wave can be selectively derived by a low-pass filter and a shock wave can be cut off, thereby preventing an erroneous earthquake level determination. In addition, the magnitude of the earthquake can be classified into several classes based on the output signal of the seismic device, and the magnitude of the earthquake can be determined based on the length of the duration of the earthquake. Therefore, an appropriate seismic operation can be performed according to the magnitude and duration of the earthquake.

Further, the gas meter of the present invention can selectively derive only the seismic wave by the low-pass filter, and can cut off the shock wave, thereby preventing malfunction of the shut-off valve. In addition, the magnitude of the earthquake can be classified into several classes based on the output signal of the seismic device, and the magnitude of the earthquake can be determined based on the length of the duration of the earthquake. Therefore, appropriate gas shutoff can be performed according to the magnitude and duration of the earthquake.

[0061]

Further, since the seismic sensor has a small and lightweight configuration and can perform high-precision measurement, a small and lightweight gas meter excellent in earthquake response can be realized.

Thus, the acceleration of the earthquake is accurately detected,
By considering the time factor, an appropriate determination of the earthquake level can be made, and a realistic and reliable safety measure can be taken.

[0064]

[Brief description of the drawings]

FIG. 1 is a perspective view showing a seismic sensor 10 according to the present invention.

FIG. 2A is a sectional view of a sensor S1, and FIG.
(2) is a cutaway perspective view showing the sensor S1.

FIG. 3 shows a seismic sensor 10 and a gas meter 50 according to the present invention.
FIG. 3 is a block diagram showing an electric circuit of FIG.

FIG. 4 is an electric circuit diagram showing a specific configuration of a low-pass filter 42.

FIG. 5 is a graph showing frequency components of a seismic wave and a shock wave.

FIG. 6 is a diagram illustrating characteristics of a low-pass filter 42;

FIG. 7 is a graph showing experimental results of output voltage characteristics with respect to vibration acceleration.

FIG. 8 is a partially cutaway perspective view of a gas meter 50 according to one embodiment of the present invention.

FIG. 9 is a system diagram showing a gas flow path and an electric block of the gas meter 50.

FIG. 10 is a conceptual diagram showing a determination area of an earthquake level.

FIG. 11 is a flowchart illustrating an earthquake level determination method according to the present invention.

FIG. 12 is a block diagram showing another example of the electric circuit of the gas meter according to the present invention.

13 (a) is a graph showing a temporal change of seismic intensity, and FIG. 13 (b) is a graph showing a frequency distribution of the seismic intensity.

FIG. 14 is a block diagram illustrating an example of a seismic intensity measurement method using the gas meter of FIG.

FIG. 15 is a configuration diagram showing an example of a typical prior art.

FIG. 16 is a graph showing characteristics of the prior art of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Seismic sensor 15 Pendulum 16, 17 Electrode 19 Cantilever support part 50 Gas meter 52 Shut-off valve 55 Circuit board 60, 61 Passage 62 Indicator lamp 71 AD conversion circuit 72 CPU

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Masazo Fujisawa Osaka Gas Co., Ltd. 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka (56) References JP-A-4-158226 (JP, A) Kaisho 51-155681 (JP, U) Shokai 63-195233 (JP, U) Shokai 3-291535 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01H 1 / 00 G01V 1/00 G01V 1/16 G01V 1/28

Claims (2)

(57) [Claims] 1. A seismic level determination method using a seismic sensor that outputs a signal that continuously changes with respect to the acceleration of an earthquake, wherein the seismic sensor is a cantilevered conductive pendulum, A pair of opposing electrodes spaced apart in the direction of oscillation of the pendulum, a pair of conductive substrates supporting and electrically connecting the opposing electrodes, and a pair of intervening portions between the mounting portion of the pendulum and the conductive substrate A low-pass filter comprising: a seismic sensor comprising a glass layer; and a capacitance detecting means for detecting a capacitance between the pendulum and each counter electrode, wherein a cutoff frequency f0 is set in a range of 5 to 10 Hz. The seismic sensor output signal is passed through, the magnitude of the output signal of the low-pass filter is divided at a plurality of discrimination levels to set a plurality of judgment areas, and the earthquake duration time and each judgment area are set in advance. And the reference time To, seismic level determination method characterized by determining the seismic level. 2. A gas passage for guiding a gas supplied from a gas inlet to a gas outlet, a gas measuring means for measuring a gas flow rate in the gas passage, and a shutoff valve for shutting off the gas passage. A seismic sensor that outputs a signal that continuously changes with respect to the acceleration of an earthquake, and a cutoff frequency f0 is set within a range of 5 to 10 Hz, and a frequency component of an output signal of the seismic device A low-pass filter for removing a frequency component higher than the cut-off frequency f0, a signal discriminating means for discriminating an output signal of the low-pass filter at a plurality of discrimination levels, and for each determination area divided by an earthquake duration and a plurality of discrimination levels. And a duration determining means for comparing with a predetermined reference time, wherein the seismic sensor is a cantilever-supported conductive pendulum, and is arranged at a distance in a vibration direction of the pendulum. A seismic sensor comprising a pair of opposing electrodes, a pair of conductive substrates supporting and electrically connected to the opposing electrodes, and a pair of glass layers interposed between the pendulum attachment portion and the conductive substrate; And a capacitance detecting means for detecting a capacitance between the pendulum and each of the opposing electrodes, and operating the shutoff valve based on each determination result of the signal discriminating means and the duration determining means. A gas meter characterized by the following.