JPH1114546A - Gas detector, gas warning device, combustion device and safety device for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas detector by which a gas concentration can be detected with high reliability. SOLUTION: A light detecting sensor 11 is installed in such a way that a gas sensor 30 which is reacted with carbon monoxide gas in a measuring atmosphere and whose discoloration degree is changed according to its concentration and with the passage of time is used and that the discoloration degree of the gas sensor 30 is measured. A detection current from the light detecting sensor 11 is supplied to a variable oscillator 20 as a concentration detecting means, and a gas concentration is converted into a change in an oscillation frequency. The gas concentration is supplied to a control part 32. When it is at a prescribed gas concentration or higher, a transistor Q3 is turned on, and an alarm 34 is operated. When a living-body imitation-type chemical sensor is used as the gas sensor 30, a sensor output which is related nearly to the gas concentration and to the generation time of the gas is obtained. Since the living-body imitation-type chemical sensor is reversible, a variation due to a change with the passage of time in the absorption characteristic and the diffusion characteristic of the gas is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas detection device for measuring the concentration of carbon monoxide gas (CO gas) in a room or the like, a gas alarm device using the same, a combustion device, and a vehicle safety device. In detail, a sensor that detects a gas concentration in the measurement atmosphere that exceeds a standard concentration using a carbon monoxide gas detection sensor that causes a reversible reaction is used. Related to devices and the like.

[0002]

2. Description of the Related Art Combustion devices such as gas heaters (gas stoves and fireplaces), gas baths, and water heaters are used indoors, so that carbon monoxide poisoning due to incomplete combustion becomes a problem. ing. In order to prevent this gas poisoning, it is essential to use a gas detector.

[0003]

Although gas detectors are already commercially available, their detection accuracy is not sufficient and there are many variations. In addition, the detection accuracy changes with time and aging, and the detection accuracy deteriorates with time.

Therefore, the present invention proposes a highly reliable gas detector and a combustion device using the same.

[0005]

In order to solve the above-mentioned problems, a gas concentration detecting device according to the present invention reacts with carbon monoxide gas in a measurement atmosphere and changes the degree of discoloration depending on its concentration and time. Is used, a light detection sensor for measuring the degree of discoloration of the gas sensor is provided, and a detection current from the light detection sensor is supplied to concentration detection means, and the concentration of carbon monoxide gas in the measurement atmosphere is detected. It is characterized by having been made.

Further, in the alarm device according to the present invention, an oscillating frequency and a detection voltage corresponding to the gas concentration are supplied to the microcomputer control unit, and an alarm is issued when the carbon monoxide gas concentration being measured becomes higher than the reference concentration. It is characterized by the following.

In the combustion apparatus according to the present invention, the oscillation frequency and the detection voltage corresponding to the gas concentration are supplied to the microcomputer control unit, and when the carbon monoxide gas concentration being measured becomes equal to or higher than the reference concentration, the raw gas is supplied. The gas control valve is closed.

Further, in the vehicle safety device according to the present invention, the gas sensor is installed in the vehicle to detect the concentration of carbon monoxide gas in the vehicle, and the oscillation frequency and the detected voltage corresponding to the gas concentration are controlled by the microcomputer. And when the concentration of carbon monoxide gas in the vehicle is equal to or higher than the reference concentration, the engine of the vehicle is stopped.

According to the present invention, by using a biomimetic chemical sensor as a gas sensor, a sensor output substantially related to gas concentration and gas generation time can be obtained. By detecting the change in the sensor output as a change in frequency or voltage, a detection output (frequency change output or voltage change output) related to the concentration of carbon monoxide gas in the measurement (detection) atmosphere and the detection time is obtained. Since the concentration of CO gas can be easily detected by this detection output, an alarm can be sounded or the gas supply valve can be closed by using this output.

Since the biomimetic type chemical sensor is reversible, fluctuations in gas absorption (uptake) and discrete (release) characteristics due to aging and aging are small.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a gas detection device and the like according to the present invention will be described in detail with reference to the drawings.

Since the carbon monoxide gas sensor (CO sensor) used in the present invention is a biomimetic chemical sensor, the CO sensor will be described first. This CO sensor is a biomimetic chemical sensor born by combining biotechnology with monocurate engineering.

The principle of CO sensing is as follows.
There is hemoglobin that carries oxygen in blood in a living body, and this hemoglobin absorbs oxygen in the lungs and carries it to muscles in the body. This hemoglobin is about 2 times more oxygen than CO gas.
Due to the 50 times higher affinity, poisoning occurs at high CO gas concentrations.

Among these hemoglobins, a substance called porphyrin which plays a role of binding to and releasing from oxygen, and porphyrin absorbs light when bound to oxygen and when not bound to oxygen. There is a property that the wavelength is different. That is, hemoglobin bound to oxygen has a bright red color, while hemoglobin that is not bound has a black color.

The CO sensor used in the present invention utilizes the function (biochemical reaction) of this porphyrin. The base material of the CO sensor is cyclodextrin,
This serves as a keyhole to catch CO gas. CO gas-loaded cyclodextrin and CO
By combining a chromophore called a chromophore to distinguish from cyclodextrin that has not taken up gas, it is distinguished whether or not CO gas is taken up by a change in color. Furthermore, a CO sensor is formed by connecting cyclodextrin and chromophore to a transparent and porous silicon oxide-based oxygen surface by hydrogen bonding.

Since the CO sensor uses a biochemical reaction, if the CO sensor is placed in an atmosphere having a constant concentration, it does not always maintain a constant reaction color. In other words, if the CO sensor is left in a CO atmosphere of a certain concentration, it will react sequentially with the CO gas in that atmosphere and the discoloration will proceed. proceed. However,
In a place where the concentration is low, since the cyclodextrin reacts so as to separate the CO gas, there is a branch point that seems to be unreacted due to the balance between gas adsorption and separation.

That is, the reaction of discoloration in response to CO gas and the reaction of reacting with oxygen to return to the original state proceed simultaneously, and as a result, depending on the CO gas concentration, The discoloration reaction time for changing from translucent color to black via gray will be different. By measuring the change in the discoloration speed, it is possible to measure the concentration of the CO gas in the atmosphere where the CO sensor is placed.

The rate of change and the amount of change can be freely set to some extent by the amount of cyclodextrin added. By the way, Japanese standards differ depending on the bathroom, living room, and kitchen, but 50 ppm to cover both with the same sensor.
In this case, a CO sensor that is used to detect within 15 minutes at 200 ppm and to detect within 5 minutes at 550 ppm is used to prevent detection. As a CO sensor that satisfies such a standard, “S50S” (model) gas sensor manufactured by Quontum Co., Ltd. can be exemplified.

The CO gas concentration in the CO sensor gradually increases while repeatedly taking in and releasing the CO gas. FIG. 3 is a graph showing the measured sensor transmittance when the CO sensor is placed in a CO gas atmosphere of 200 ppm, and the transmittance decreases with time. This is because the color is changed by taking in the CO gas.

In FIG. 2, after 15 minutes, the transmittance is reduced to about 1/3. When the CO sensor is left open in the air after elapse of 15 minutes, the captured CO gas is gradually released, and after a predetermined time elapses, the transmittance is almost restored to the original transmittance. Therefore, it can be seen that the CO sensor has reversible binding and release to the CO gas. Since the transmittance is restored to the original transmittance, the light transmittance is not significantly affected by aging and aging. Therefore, there is no significant deterioration of the density measurement characteristics.

FIG. 4 is a graph when the CO sensor is placed in a 550 ppm CO gas atmosphere.
The change in transmittance per time is larger than that in the case of m. Then, the time required until the transmittance becomes constant becomes shorter. And when it returns to the air, it returns to the original transmittance again.

On the other hand, when the CO gas concentration is very low, for example, about 50 ppm, the light transmittance is temporarily lowered by taking in carbon monoxide gas gas as shown in FIG. Since release (release) is also performed, it can be seen that the light transmittance hardly changes when the CO gas uptake and the release gas are performed alternately and viewed as a whole.

Thus, by utilizing the correlation between the change in the light transmittance and the concentration of the carbon monoxide gas, the concentration of the CO gas indoors can be detected almost indirectly, albeit indirectly.

There are various ways of detecting the change in transmittance. The change in transmittance can be considered as a change in voltage or current, or a change in frequency.

FIG. 1 shows a gas detector 1 according to the present invention.
In the embodiment of No. 0, a change in light transmittance is regarded as a change in oscillation frequency.

In this gas detector 10, a power supply + B
A light emitting element 12 functioning as an optical sensor 11
And the light receiving element 18 are connected. In the figure, a light emitting diode is used as the light emitting element 12, and a light receiving diode is used as the light receiving element 18. A constant current source 14 is provided between the light emitting diode 12 and the power supply + B so as to make the current flowing through the light emitting diode 12 constant so that the light emission amount is always constant. In the figure, a field effect transistor Q1 and a variable resistor 16 for controlling its current value are shown.
It is composed of

Light emitting diode 12 and light receiving diode 18
The above-mentioned CO is so arranged as to block the optical path.
A sensor 30 is provided. In particular, the CO sensor 30 is placed such that the translucent silicon oxide base constituting it is orthogonal to the optical path. The CO sensor 30 is disposed in a shield case (not shown) constituting the light detection sensor 11 for blocking external light.

A variable oscillator 20 is provided in the current path of the light receiving diode 18. The variable oscillator 20 includes a charge / discharge capacitor 22 connected between the light receiving diode 18 and the ground, as shown in the figure, and a voltage detecting means for detecting a charge voltage of the charge / discharge capacitor 22 and outputting a high-level detection signal when the voltage exceeds a predetermined voltage. 24 and a control transistor Q connected to both ends of the capacitor 22 and controlled on / off by a detection signal.
And 2.

A voltage (oscillation voltage) corresponding to the oscillation frequency obtained from both ends of the capacitor 22 is supplied to a control unit 32 constituted by a microcomputer.

The amount of transmitted light reaching the light receiving diode 18 differs depending on the degree of discoloration of the silicon base constituting the CO sensor 30. The current flowing through the light receiving diode 18 passes through the CO sensor 30 and passes through the light receiving diode 1.
It changes depending on the amount of transmitted light that has reached 8. Since the diode current flows into the capacitor 22, the charging time for the capacitor 22 changes depending on the amount of transmitted light.

The voltage across the capacitor 22 increases due to the diode current. When the voltage across the capacitor 22 rises to a specified voltage, a high-level detection output is obtained from the voltage detection means 24. This detection output turns on the transistor Q2. When the transistor Q2 turns on, the capacitor 22 is rapidly discharged. When the capacitor 22 discharges, the voltage across the capacitor 22 becomes zero. When the voltage between both ends becomes zero, this is detected by the voltage detecting means 24, the detection output is inverted to low level, and the transistor Q2
Is turned off, and the capacitor 22 is charged again.

The charging / discharging operation is repeated, so that an oscillation state is established, and the voltage across the capacitor 22 becomes the solid line L in FIG.
It changes like a sawtooth like a. When the CO sensor 30 is not used (in a measurement atmosphere having a gas concentration of 50 ppm or less), the transmitted light amount is the largest since the silicon base has not changed color. The current value of the variable current source 14 is controlled so as to oscillate at a frequency fa of, for example, 1 kHz by charging and discharging when the gas atmosphere in which the CO sensor 30 is placed has a gas concentration of 50 ppm or less.
This value is arbitrary. At this time, it is assumed that a voltage change waveform as shown by the solid line La in FIG. 2 is obtained.

When the CO sensor 30 reacts with the CO gas, the silicon oxide base is discolored in accordance with the concentration and the light transmittance is reduced, so that the amount of transmitted light reaching the light receiving diode 18 is reduced. Then, the time until the capacitor 22 is charged up to the voltage detection level Vx of the voltage detecting means 24 (see FIG. 2) becomes longer, and as a result, the variable oscillator 20
(= Fb), and the voltage across the capacitor at that time becomes as shown by the chain line Lb in FIG. Therefore, the times Ta and Tb required to reach the reference voltage level Vx are different.

For example, when the time Ta has a gas concentration of 50 ppm or less as shown in FIG. 5, the oscillation frequency corresponding to the amount of transmitted light is fa, and the oscillation frequency fa is converted into a voltage. The time is Ta, and the oscillation frequency corresponding to the transmitted light amount when the gas concentration is 550 ppm shown in FIG. 4 is fb, and the oscillation frequency fb reaches a specified value Vx when the oscillation frequency fb is converted into a voltage. When the time is Tb, the measurement time T is Tb.
If it is less than b, it can be determined that the dangerous gas concentration has not yet been reached. When the measurement time T becomes longer than Tb,
Since it can be estimated that the gas concentration is equal to or higher than the specified gas concentration, the gas concentration in the measurement atmosphere can be almost certainly detected by the measurement time T.

The control section 32 measures the time Ta and Tb until reaching the reference voltage level Vx. When the measurement time T becomes equal to or longer than Tb, a high-level control signal SQ is output. This turns on the control transistor Q3, and when used as a gas alarm device, the alarm device 34 such as a buzzer operates. I do. Activating the alarm device 34 can draw the user's attention.

FIG. 6 shows an embodiment applied to a combustion apparatus in which a fuel valve of a combustor provided in a gas appliance is closed to forcibly stop combustion. In this example, the fuel valve is configured as an electromagnetic valve. Then, the solenoid valve control relay 36 is driven to control the fuel valve to close. Thereby, generation of CO gas can be suppressed.

In addition, the present invention can be applied to instantaneous water heaters, fan heaters, gas baths, automobiles, and the like.

FIG. 7 shows a combustion device 40 such as an instantaneous water heater.
The present invention is applied to a water heater body 4
2 is provided with a burner 44 in which a gas pipe 46 is provided.
Is supplied with raw gas. A heat exchanger 48 is disposed immediately above the burner 44, and a water distribution pipe 50 is attached to the outer periphery thereof, and the absorbed water is discharged as warm water.

The burner 44 is provided with an igniter 52 and a frame rod 54 for monitoring the combustion state. A water switch 64 is provided in the water distribution pipe 50, and water absorption is stopped when the amount of water reaches a certain level or less.

Each of the gas pipes 46 is provided with first and second on-off valves 66 and 68 each having an electromagnetic valve structure. In this example, the first on-off valve 66 is controlled to open and close by the relay 36 described above. You. The second on-off valve 68 is connected to the second relay 70
Is controlled by

All of these controls are performed by the control device 60, which includes a control unit 32 composed of the CPU described above.
Is installed. The control device 60 is driven by a battery power supply (3 volts or more) 62. If such a battery power supply 62 is used instead of the AC power supply, electric shock or the like will not occur.

FIG. 8 shows an embodiment in which the current flowing through the light receiving diode 18 is converted into a voltage to detect the gas concentration. As shown in the figure, a resistor 80 as current / voltage conversion means is connected in series to the light receiving diode 18, and a voltage between both ends of the resistor 80 is supplied to the control unit 32. The control unit 32 measures the voltage value by digitally converting the voltage between both ends.

When the gas concentration on which the CO sensor 30 is placed is low, the gas almost passes through the CO sensor 30. At this time, a large diode current flows, so that the voltage across the resistor 80 at that time is high. On the other hand, when the gas concentration increases, the amount of transmitted light decreases, and accordingly, the diode current becomes difficult to flow. Therefore, the voltage across the resistor 80 at that time decreases. Therefore, the gas concentration can be detected by detecting the voltage between both ends. When the gas concentration exceeds the specified value, the control transistor Q3 is turned on and the alarm device 32 operates.

In the combustion apparatus shown in FIG. 9, the relay 36 for controlling the opening and closing of the solenoid valve is controlled to cut off the gas supply. As a result, generation of CO gas can be stopped.

FIG. 10 shows a safety device 90 that detects the CO gas concentration in the vehicle and, when the concentration reaches a dangerous level, controls the engine to stop and exhaust only when the vehicle is stopped. This is the case. The embodiment of FIG. 10 is an application of the circuit configuration of FIG. 6. In this embodiment, a control switch 84 is provided on a power supply path for an ignition circuit 82 of an automobile, and the control switch 84 is controlled by a relay 86. This is the case when the following is done.

For some reason, if the CO concentration in the vehicle rises abnormally and exceeds the lethal dose, it is dangerous. Therefore, the optical sensor 11 having the above-described CO sensor 30 is installed at an appropriate position in the vehicle.

When the gas concentration in the vehicle exceeds a reference value (an arbitrary gas concentration before reaching a lethal amount) with the engine running, the control transistor Q3 is turned on by the judgment output SQ from the control unit 32. As a result, the relay 86 is energized and the control switch (normally closed switch) 8
When the switch 4 is turned off, the operation of the ignition circuit 82 stops. Thus, the engine can be forcibly stopped, so that the gas concentration in the vehicle does not increase from the time of gas detection (an arbitrary gas concentration before reaching a lethal amount). That is, it operates as a safety device.

In addition to forcibly cutting off the power supply path of the circuit, for example, a forced stop circuit (not shown) is provided so that the operation of the ignition circuit 82 itself is stopped, and this forced stop circuit is controlled by the above-described transistor Q3. It can also be configured to do so. Therefore, the above-described embodiment is merely an example.

FIG. 11 shows an embodiment of a vehicle safety device 90 to which the circuit configuration of FIG. 9 is applied. Also in this case, relay 8
The normally closed control switch 84 is controlled by 6 so that the operation state of the ignition circuit 82 is controlled. Therefore, when the gas concentration equal to or higher than the reference value is detected, the control switch 84 is turned off by the same operation as in FIG. 10, so that the operation of the ignition circuit 82 is stopped and the engine can be forcibly stopped.

The embodiments described above are merely examples, and the present invention can be applied to all conceivable gas appliances and the like.

[0051]

As described above, in the gas detection device according to the present invention, a biomimetic chemical sensor is used as a carbon monoxide gas sensor, and the carbon monoxide gas concentration is detected in a state converted into a frequency change or a voltage change. It is like that.

According to this, it is possible to stably detect the carbon monoxide gas. Therefore, when this gas detection device is used for a gas alarm device, a combustion device, a vehicle safety device, or the like, a predetermined value is set. It is characterized in that the gas concentration can be accurately detected and the corresponding processing can be performed.

In addition, since the gas sensor has relatively little influence on the detection accuracy due to aging and aging, the detection accuracy is less deteriorated. Therefore, it has a feature that can realize a highly reliable alarm device, combustion device, and automobile safety device.

[Brief description of the drawings]

FIG. 1 is a system diagram (part 1) showing an embodiment of a gas detection device according to the present invention.

FIG. 2 is an explanatory diagram of the operation.

FIG. 3 is a curve diagram showing a change in transmittance at a gas concentration (200 ppm).

FIG. 4 is a curve diagram showing a change in transmittance at a gas concentration (550 ppm).

FIG. 5 is a curve diagram showing a change in transmittance at a gas concentration (50 ppm).

FIG. 6 is a system diagram (part 2) showing an embodiment of the gas detection device according to the present invention.

FIG. 7 is a system diagram showing one embodiment of a combustion device according to the present invention.

FIG. 8 is a system diagram (part 3) showing an embodiment of the gas detection device according to the present invention.

FIG. 9 is a system diagram (part 4) showing an embodiment of the gas detection device according to the present invention.

FIG. 10 is a system diagram (part 1) showing an embodiment of a vehicle safety device according to the present invention.

FIG. 11 is a system diagram (part 2) showing an embodiment of a vehicle safety device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Gas detector 11 Optical sensor 12 Light emitting diode 18 Light receiving diode 20 Variable oscillator 22 Charging / discharging capacitor 24 Voltage detecting means 30 CO sensor 32 Control unit 34 Alarm 36 Relay 80 Voltage detecting means 90 Safety device Q1-Q3 Control transistor

Claims (12)

[Claims] 1. A gas sensor which reacts with a carbon monoxide gas in a measurement atmosphere and changes its discoloration degree depending on its concentration and time is used. A light detection sensor for measuring the discoloration degree of this gas sensor is provided, and said light sensor is provided. A gas detection device characterized in that a detection current from a detection sensor is supplied to a concentration detection means to detect a concentration of carbon monoxide gas in the measurement atmosphere. 2. A variable oscillator is used as the concentration detecting means. A detection current from the light detection sensor is supplied to the variable oscillator, and the carbon monoxide is changed based on an oscillation frequency which changes according to the detection current. The gas detection device according to claim 1, wherein the gas concentration is detected. 3. The gas alarm device according to claim 1, wherein the oscillation frequency is supplied to a microcomputer control unit, and an alarm is issued when the concentration of carbon monoxide gas being measured becomes equal to or higher than a reference concentration. 4. The gas sensor is installed in a vehicle of an automobile to detect the concentration of carbon monoxide gas in the vehicle, and the oscillation frequency is supplied to a microcomputer control unit so that the concentration of carbon monoxide gas in the automobile is equal to or higher than a reference concentration. A vehicle safety device characterized in that the engine of the vehicle is stopped when the vehicle is turned off. 5. The vehicle according to claim 4, wherein a power switch is provided in a power path of an ignition circuit of the engine, and the power switch is controlled based on the gas detection output. Safety device. 6. A gas control valve for supplying raw gas is closed when the oscillation frequency is supplied to a microcomputer control unit and the concentration of carbon monoxide gas being measured becomes equal to or higher than a reference concentration. And combustion equipment. 7. The gas according to claim 1, wherein current / voltage conversion means is used as said concentration detection means, and said carbon monoxide gas concentration is detected based on the detected voltage. Detection device. 8. A gas alarm device, wherein the detection voltage is supplied to a microcomputer control unit, and an alarm is issued when the concentration of carbon monoxide gas being measured becomes equal to or higher than a reference concentration. 9. The gas sensor is installed in an automobile to detect the concentration of carbon monoxide gas in the automobile, the detected voltage is supplied to a microcomputer control unit, and the concentration of carbon monoxide gas in the automobile is equal to or higher than a reference concentration. A vehicle safety device characterized in that the engine of the vehicle is stopped when the vehicle is turned off. 10. The vehicle according to claim 9, wherein a power switch is provided in a power path of an ignition circuit of the engine, and the power switch is controlled based on the gas detection output. Safety device. 11. The gas control valve for supplying raw gas is closed when the detected voltage is supplied to a microcomputer control unit and the concentration of carbon monoxide gas being measured becomes equal to or higher than a reference concentration. And combustion equipment. 12. The combustion device according to claim 6, wherein the combustion device is an instantaneous water heater or a gas bath disposed indoors.