JPH08329370A - Gas abnormality monitor device - Google Patents

Abstract

PURPOSE: To judge abnormality in a short time as to the gas abnormality monitor device which uses an electrostatic capacity type pressure sensor. CONSTITUTION: A pressure detecting means 21 measures gas pressure which is supplied from a gas supply source 11 and adjusted by a pressure adjusting means 20. If gas leaks when a flow rate detecting means 22 confirms that the measured gas flow rate is 0, the gas pressure in piping drops with time. The variation in the gas pressure is monitored by a pressure detecting means 21 and decided by a decision means 23 to judge abnormality when the pressure drop is larger than a specific value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas using a small-sized and high-performance capacitance type pressure sensor for converting a pressure change into a capacitance change of an electrode provided on a diaphragm and further converting it into an electric output. Gas regulators such as pressure regulators and gas meters.

[0002]

2. Description of the Related Art In recent years, in order to prevent an explosion accident due to a gas leak or a fire accident due to forgetting to turn off a gas appliance, for example, regarding a gas meter, the gas leak downstream from the gas meter and the usage status of the gas appliance are monitored, and in the event of an emergency. Is considering incorporating a gas leak detection device that automatically shuts off the gas supply into the gas meter, and for the pressure regulator, check the abnormality of the pressure regulator itself and the safety management from the LP gas cylinder to the gas meter. Some people are considering installing an automatic gas leak detector. When the pressure adjusting function of the LP gas pressure adjuster is operating normally, the gas supply pressure is kept between 230 and 330 mmH ₂ O when the gas appliance is in use, and there is no abnormality in the gas supply pressure. Is monitored by a pressure sensor. Further, when there is an abnormality such as a gas leak in the gas facility, for example, when the shutoff valve is operated and the gas pipe is closed, the gas pressure gradually decreases due to the gas leak (several mmH ₂ O to several 10 mmH ₂ O). By monitoring this decrease in gas pressure, it is possible to detect whether or not an abnormality such as a gas leak has occurred in the gas facility. A conventional pressure sensor for detecting these pressures with high precision in a short time is disclosed in Japanese Patent Laid-Open No. 57-97422.
The one shown in Japanese Patent Publication was common. The configuration will be described below with reference to FIG. As shown in FIG.
The gap between the substrate 1 on which the electrodes 4 and 5 are formed and the diaphragm 2 is fixed by sealing the diaphragm 2 to the substrate 1 with a sealing layer 6 made of sealing glass containing beads 8, and the diaphragm 2 is pressed by pressure. The change in the capacitance caused between the electrodes 4 and 5 due to the deformation and change in the distance between the electrodes is converted into an electric output change. Further, the pressure sensor is driven by a battery incorporated in these devices, and it is desired to use the battery without replacing the battery for a long period of about 10 years, so it is necessary to consume as little power as possible.

[0003]

However, in order to achieve high capacity and high sensitivity, the gap between the electrodes should be about 0.1 μm.
When the size is reduced to about several tens of μm, the conventional electrostatic capacitance type pressure sensor has a particle size distribution in the minute beads 8.
In addition to the difficulty of uniform dispersion of the sealing glass layer, a sealing glass layer is sandwiched therebetween, which causes gap variation. Therefore, the conventional electrostatic capacitance type pressure sensor has a problem that the sensor characteristics vary and the accuracy of the sensor is low.

When an abnormality such as a gas leak in the gas facility is detected, for example, the measured pressure is gradually decreased due to the gas leakage, and whether the gas facility is abnormally leaked by monitoring the decrease in the gas pressure. There is a method to detect whether or not the pressure sensor is low in accuracy.In this case, it is necessary to monitor a larger pressure drop in consideration of variations in sensor characteristics. In the event of a gas leak, there was a problem that we could not immediately respond.

Further, when the accuracy of the pressure sensor is low, when the abnormality such as gas leak in the gas equipment is detected, the time for pressure measurement and the determination of normality / abnormality becomes long, so that the pressure sensor is not measured. There is a problem that the power consumption is large and the battery is consumed quickly.

Further, if there is a large variation in the characteristics of the pressure sensor, it is necessary to adjust the pressure sensor, resulting in poor mass productivity and high manufacturing cost.

Actually, a fixed substrate 1 and a diaphragm 2 (thickness: 0.15 mm) made of ceramic are prepared as a pressure sensor, and gold resinate is used as the first electrode 4 and the second electrode 5 on the fixed substrate 1 and the diaphragm 2, respectively. It was formed by a screen printing method, degreased and baked to a thickness of 0.1 μm. Further, a glass paste containing 0.5% by weight of glass fiber (fiber diameter 5 ± 0.05 μm, fiber length 25 μm) and beads 8 having a variation of several μm were mixed in a low melting glass and printed on the fixed substrate 1. To form the sealing layer 6. Then, in a state where the first electrode 4 and the second electrode 5 are arranged so as to face each other, heat load molding is performed to integrally bond the fixed substrate 1 and the diaphragm 2 with the sealing layer 6, and the first embodiment It was connected to the same charge / discharge time detection type detection circuit as described above, subjected to non-linearity correction, gain and offset adjustment, and converted into a predetermined voltage output. As a result, the dispersion of the glass fibers in the sealing layer 6 and the dispersion of the beads 8 were overlapped with each other, and the dispersion of the gap of several μm occurred, and the gas pressure could be detected only with the accuracy of 20 mmH ₂ O. When this capacitance type pressure sensor is incorporated in the pressure regulator, the presence or absence of gas leakage is judged when the actual pressure regulated by the pressure regulator is 315 mmH ₂ O (measured by another standard pressure sensor). Takes 2 minutes to
The battery life was about 7.5 years.

The present invention solves such a conventional problem, and shortens the time for determining an abnormality such as a gas leak in a gas facility in a gas abnormality monitoring device, suppresses the consumption of a battery, and causes a gas abnormality. The purpose is to reduce the manufacturing cost of the monitoring device.

[0009]

In order to achieve the above object, the present invention provides a pressure detecting means for detecting a gas pressure in a gas facility, a flow rate detecting means for detecting a gas flow rate in the gas facility, and Judgment means for judging an abnormality in the gas facility by an electric signal from the pressure detection means and the flow rate detection means,
The pressure detection means comprises a fixed substrate made of an electrically insulating material having a first electrode formed on the surface thereof, and a second electrode formed on the surface of the pressure detection means. A diaphragm made of an electrically insulating elastic material, and an adhesive layer and a spacer formed separately on at least one peripheral portion of the first electrode and the second electrode, respectively. And a capacitance-type pressure sensor in which the second electrode is opposed to each other and the fixed substrate and the diaphragm are joined via the adhesive layer and the spacer.

Further, in the electrostatic capacitance type pressure sensor used for the pressure detecting means, a spacer is provided in a gap between a plurality of adhesive layers formed on the peripheral portion of at least one of the first electrode and the second electrode. is there.

Further, in the electrostatic capacitance type pressure sensor used in the pressure detecting means, a plurality of adhesive layers formed on the peripheral portion of at least one of the first electrode and the second electrode are provided with spacers on the outer periphery thereof. is there.

[0012]

The present invention has the following functions due to the above construction. That is, the electrostatic capacitance type pressure sensor used in the pressure detecting means of the gas abnormality monitoring device of the present invention is configured such that the adhesive layer and the spacer are separated at the periphery of at least one of the fixed substrate and the diaphragm, and the fixed substrate is manufactured. Since the adhesive layer can be formed while holding it with a spacer that can keep the distance between the diaphragm and the diaphragm constant, it is possible to control the gap between the fixed substrate and the diaphragm with high accuracy, and as a result, the capacitance variation of the pressure sensor is reduced. Therefore, the accuracy of the pressure detecting means for detecting the gas pressure in the gas facility is improved.

Further, by providing a spacer in the gap between a plurality of adhesive layers formed on the peripheral portion of at least one of the first electrode and the second electrode of the capacitance type pressure sensor used for the pressure detecting means, the pressure can be reduced. The variation in the capacitance of the sensor is reduced, and the accuracy of the pressure detecting means is improved.

Further, by providing a spacer on the outer periphery of a plurality of adhesive layers formed on the peripheral portion of at least one of the first electrode and the second electrode of the capacitance type pressure sensor used for the pressure detecting means, the pressure can be reduced. The variation in the capacitance of the sensor is reduced, and the accuracy of the pressure detecting means is improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1, 2 and 3.

FIG. 1 is a block diagram when the gas abnormality monitoring device of the present invention is applied to a pressure regulator. 11 is a gas supply source, 12 is a gas abnormality monitoring device (pressure regulator), 1
3 is a gas meter. The pressure adjuster 12 includes a pressure adjusting unit 20, a pressure detecting unit 21 (for example, a pressure sensor), a flow rate detecting unit 22 (for example, a flow meter), a judging unit 23 (for example, a microcomputer), and an output unit 24 (for example, a shutoff valve). Has been done.

FIG. 2 is a constitutional view of an electrostatic capacitance type pressure sensor used in the pressure detecting means 21 used in the pressure regulator 12, where (a) is a plan view and (b) is a sectional view. A fixed substrate 31 made of an electrically insulating material having a first electrode 33 formed on the surface, a diaphragm 32 made of an electrically insulating elastic material having a second electrode 34 formed on the surface, and the first electrode 33. A fixed substrate 31 of an electrical edge material having an adhesive layer 35 and a spacer 36 formed on at least one peripheral portion of the second electrode 34, and a first electrode 3 formed on the surface, and a second fixed substrate 31. The electrode 32 and the diaphragm 32 made of an electrically insulating elastic material formed on the surface are joined via an adhesive layer 35 and a spacer 36 so that the first electrode 33 and the second electrode 34 are arranged to face each other. are doing. Here, the second electrode 34 is divided into a measurement electrode (central portion) and a reference electrode (outer peripheral portion), and the measurement capacitance and the reference capacitance are calculated and compensated to obtain temperature characteristics and nonlinearity. Can be very small.

That is, the fixed substrate 31 made of ceramics
And a diaphragm 32 (thickness: 0.15 mm) are prepared, and gold resinate is formed on the fixed substrate 31 and the diaphragm 32 as the first electrode 33 and the second electrode 34 by a screen printing method, and degreasing and firing are performed to obtain a thickness of 0. The thickness is 1 μm. After the glass frit with a low melting point having the same coefficient of thermal expansion as the fixed substrate is screen-printed on the fixed substrate 31 in the pattern shape shown in FIG. 2 to form the adhesive layer 35,
A glass fiber (fiber diameter 5 ±
Spacer 36 consisting of 0.05 μm and fiber length 25 μm) is drawn with a resin paste containing a small amount and spacer 3
6 is formed. In a state where the first electrode 33 and the second electrode 34 are arranged so as to face each other, heat load molding is performed,
Fixed substrate 31 and diaphragm 32 via a spacer 36
And are joined together by an adhesive layer 35.

In the above capacitance type pressure sensor, a charging / discharging circuit is formed by each of the measuring electrode (central portion) and the reference electrode (outer peripheral portion) of the second electrode 34, and the charging time difference between the respective capacitances is formed. The pressure detection means 21 is manufactured by connecting to a detection circuit of a charge / discharge time detection type that generates a pulse output corresponding to, and performing nonlinearity correction, gain and offset adjustment, and converting to a predetermined voltage output.

FIG. 3 is a flow chart showing the gas leak detection operation of the pressure regulator. In a state where the present apparatus is started, the gas is supplied to the output means 24 (for example, a shutoff valve) to supply gas (step 1), the gas supply source 11
The gas pressure supplied from the gas and adjusted by the pressure adjusting means 20 is measured by the pressure detecting means 21 (step 2). When a small amount of gas is leaked when it is confirmed that the gas flow rate measured by the flow rate detection means 22 is 0 (step 3), the gas pressure in the pipe gradually decreases with time. The change in pressure is monitored by the pressure detecting means 21, and is judged by the judging means 23 such as a microcomputer. If the pressure drop is larger than a predetermined value, it is judged that there is an abnormality, that is, gas leakage (step 4). When it is judged that there is a gas leak, the output means 24 (cutoff valve) is operated to stop the gas supply (step 5). When the determination means 23 determines that there is no gas leakage, the operation returns to the output operation (step 1) again, and the gas supply is continued to perform measurement / judgment to monitor a long-term gas leakage of the pressure regulator 12. To do.

When the above capacitance type pressure sensor is used as the pressure detecting means 21, the shutoff valve 24 and the flow rate detecting means 2 are used.
2 and the pressure detection means 21 are operated to operate the pressure regulator 12
Gas pressure of 315 mmH ₂ O (measured by another standard pressure sensor)
mmH ₂ O is reduced to 275mmH ₂ O) was measured. As a result, it was possible to determine the small gas leak in the gas pipe by about 20 seconds. Since the gas leakage could be detected and discriminated in such a short time, the power consumption of the pressure sensor and the gas abnormality monitoring device could be reduced, and the battery operated correctly without replacing the battery for 10 years. In addition, the variation in the characteristics of the pressure sensor is small, so the manufacturing cost is about half that of the conventional one.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 shows another embodiment of the electrostatic capacitance type pressure sensor used for the pressure detecting means 21, in which (a) is a plan view,
(B) is a sectional view. Adhesive layer 35 formed on the peripheral portion of at least one of the first electrode 33 and the second electrode 34.
The spacer 36 is provided on the outer periphery of the first embodiment, which is a difference from the capacitance type pressure sensor used in the first embodiment, and other sensor configurations and circuit configurations are the same as those in the first embodiment. As a result, the gap between the electrodes is determined by the thickness of the spacer 36 and is not affected by the sealing glass, so that the accuracy of the sensor is improved.

Therefore, even when this capacitance type pressure sensor is used, the same effect as that of the first embodiment can be obtained.

FIG. 5 is a block diagram when the gas abnormality monitoring device of the present invention is applied to a gas meter. Reference numeral 12 is a pressure regulator, 13 is a gas meter, and 14 is a gas appliance.
The gas meter 13 includes a pressure detection unit 21 (for example, a pressure sensor), a flow rate detection unit 22 (for example, a flow meter), and a determination unit 2.
3 (for example, a microcomputer) and output means 24 (for example, a shutoff valve)
It consists of and.

To detect gas leakage, the output means 24 (for example, a shutoff valve) is operated, and the flow rate detection means 22 and the pressure detection means 21 detect the presence or absence of flow rate and pressure fluctuations when the gas appliance is not used, The judgment is made by the judgment means 23. That is, if a small amount of gas is leaking, the gas pressure in the pipe gradually decreases with time when the gas flow rate is zero. The state of this slight change in the gas pressure is monitored by the pressure detecting means 21, and is judged by the judging means 23 such as a microcomputer. If the pressure drop is larger than a predetermined value, it is judged that there is a gas leak, and the output means 24 ( Operate the shutoff valve). When the determining means 23 determines that there is no gas leakage, the output means 24, the pressure detecting means 21, and the flow rate detecting means 22 are operated again to measure the pressure and flow rate in the gas facility to prevent gas leakage for a long time. To monitor.

When the above capacitance type pressure sensor is used as the pressure detecting means 21, even when it is applied to the gas meter 13, it is possible to judge the minute gas leakage in the gas pipe in about 20 seconds. That is, since the gas leakage could be detected and discriminated in a short time, the power consumption of the pressure sensor and the gas abnormality monitoring device could be reduced, and the battery operated correctly without replacing the battery for 10 years. In addition, the variation in the characteristics of the pressure sensor is small, so the manufacturing cost is about half that of the conventional one.

In the gas abnormality monitoring device of the present invention,
Various materials for the capacitive pressure sensor (diaphragm, fixed substrate, electrode, mold, etc.), molding conditions (temperature, time, pressure,
Atmosphere, etc.), sensor shape (circular, square, diameter, electrode pattern, thickness, gap, etc.), circuit configuration, measured pressure,
The configuration of the pressure regulator and the gas meter as the gas abnormality monitoring device is an example, and the present invention is not limited to this example.

[0028]

As described above, according to the gas abnormality monitoring apparatus of the present invention, the following effects can be obtained.

In the gas abnormality monitoring apparatus of the present invention, the pressure detecting means for detecting the gas pressure in the gas equipment has a structure in which the adhesive layer and the spacer are separated at the periphery of at least one of the fixed substrate and the diaphragm during manufacturing. Since the adhesive layer can be formed while holding the spacer with a fixed distance between the fixed substrate and the diaphragm, the variation in the gap between the fixed substrate and the diaphragm is determined only by the variation in the spacer, and as a result, the gap is highly accurate. Can be controlled. Therefore, the capacity variation of the pressure sensor is reduced, and the accuracy of the pressure detection means for detecting the gas pressure in the gas facility is improved,
By monitoring the pressure drop of a smaller value, it is possible to determine whether the gas facility is normal or abnormal, and the following features are obtained.

(1) It is possible to shorten the determination time for abnormality such as gas leakage in the gas facility. (2) The consumption of the battery that drives the gas abnormality monitoring device can be suppressed.

(3) The manufacturing cost of the gas abnormality monitoring device can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration when a gas abnormality monitoring device according to an embodiment of the present invention is applied to a pressure regulator.

FIG. 2A is a plan view showing an embodiment of an electrostatic capacity type pressure sensor used as a pressure detecting means of the apparatus. FIG. 2B is a sectional view of the electrostatic capacity type pressure sensor.

FIG. 3 is a flowchart showing the operation of the device.

FIG. 4A is a plan view showing another embodiment of the electrostatic capacity type pressure sensor used for the pressure detecting means of the apparatus. FIG. 4B is a sectional view of the electrostatic capacity type pressure sensor.

FIG. 5 is a block diagram showing a configuration when the gas abnormality monitoring device of the present invention is applied to a gas meter.

FIG. 6 is a cross-sectional view of a capacitance type pressure sensor used as pressure detection means of a conventional gas abnormality monitoring device.

[Explanation of symbols]

 12 Pressure Regulator 14 Gas Appliance 21 Pressure Detection Means 21 Flow Rate Detection Means 23 Judgment Means 24 Output Means 31 Fixed Substrate 32 Diaphragm 33 First Electrode 34 Second Electrode 35 Adhesive Layer 36 Spacer

Claims (3)

[Claims] 1. A pressure detecting means for detecting a gas pressure in a gas facility, a flow rate detecting means for detecting a gas flow rate in the gas facility, the gas by an electric signal from the pressure detecting means and the flow rate detecting means. Determination means for determining an abnormality in the facility,
The pressure detection means comprises a fixed substrate made of an electrically insulating material having a first electrode formed on the surface thereof, and a second electrode formed on the surface of the pressure detection means. A diaphragm made of an electrically insulating elastic material, and an adhesive layer and a spacer formed separately on at least one peripheral portion of the first electrode and the second electrode, respectively. And a gas abnormality monitor having a capacitance type pressure sensor in which the second electrode is opposed to each other and the fixed substrate and the diaphragm are joined via the adhesive layer and the spacer. 2. A pressure detecting means for detecting a gas pressure in a gas facility, a flow rate detecting means for detecting a gas flow rate in the gas facility, the gas by an electric signal from the pressure detecting means and the flow rate detecting means. Determination means for determining an abnormality in the facility,
The pressure detection means comprises a fixed substrate made of an electrically insulating material having a first electrode formed on the surface thereof, and a second electrode formed on the surface of the pressure detection means. A diaphragm made of an electrically insulating elastic material, a plurality of adhesive layers formed on at least one peripheral edge of the first electrode and the second electrode, and a spacer provided in a gap between the adhesive layers. A gas abnormality monitoring device having a capacitance type pressure sensor in which the first electrode and the second electrode are arranged to face each other and the fixed substrate and the diaphragm are joined via the adhesive layer and the spacer. 3. A pressure detecting means for detecting a gas pressure in a gas facility, a flow rate detecting means for detecting a gas flow rate in the gas facility, the gas by an electric signal from the pressure detecting means and the flow rate detecting means. Determination means for determining an abnormality in the facility,
The pressure detection means comprises a fixed substrate made of an electrically insulating material having a first electrode formed on the surface thereof, and a second electrode formed on the surface of the pressure detection means. A diaphragm made of an electrically insulating elastic material, an adhesive layer formed on the peripheral portion of at least one of the first electrode and the second electrode, and a spacer provided on the outer periphery of the adhesive layer, A gas abnormality monitoring device having a capacitance type pressure sensor in which the first electrode and the second electrode are arranged to face each other and the fixed substrate and the diaphragm are joined via the adhesive layer and the spacer.