JP2903074B2 - CO gas detector - Google Patents

Description

The present invention relates to a CO gas detection device that detects a CO gas by judging a sensor output from a semiconductor sensor, and particularly relates to a device such as a water heater for a bath. From combustion equipment used intermittently
The present invention relates to a CO gas detection device that detects gas.

[Conventional technology]

At present, gas alarms are commercially available for LPG or city gas.
Low sensitivity to gas, CO gas detector or CO
Even a commercially available sensor is not sufficient in terms of gas discrimination or stability over time.

Therefore, there is a gas detector using a semiconductor sensor as a gas detection element (sensor) provided in the gas detector. The semiconductor sensor adsorbs a gas to be detected, such as CO gas, on a semiconductor surface, and detects the electric resistance of the semiconductor due to the gas adsorption as a gas concentration.

Figure 5 shows the gas sensing device having such a semiconductor sensor, 1 is a semiconductor sensor comprising a heater R ₁ and the sensing portion K, the semiconductor sensor 1 in series to the current-voltage current for conversion The detection resistor _RS is connected. V ₁ was operating power, V ₂ is the heater power supply. Figure 6 shows the characteristic of the device of FIG. 5, current flows from the power source V ₂ to the heater R _1, is a characteristic when used continuously by heating the semiconductor sensor 1 around 100 ° C.. As is clear from the figure, the sensor output (hereinafter referred to as air base) in the clean air increases with time,
The sensor output for CO gas (hereinafter referred to as CO gas sensitivity) decreases with time. Therefore, it cannot be used stably as a CO gas detector. This is because the semiconductor sensor 1 has a large change in the gas adsorption property depending on the heating temperature, and the heating temperature and the chemical adsorption property (activity) greatly change depending on the type of gas. Are arranged in order from the lowest, such as CO, alcohol, hydrogen, butane, propane, and methane.

Therefore, the present applicant has proposed an improved gas detector in Japanese Patent Publication No. 58-621 (name: CO gas alarm). Figure 7 shows a schematic arrangement of the apparatus proposed in the above publication, V ₂ is high temperature heating power source, SW ₁ is a switch, the other structure is the same as Figure 5. Figure 8 shows the characteristic of the device of FIG. 7, (upon application operating power V ₁ to the sensing portion K) energization start time, and once the number at the rate of 10 seconds power to several 10 minutes
By switching from V ₂ to V _3, the semiconductor sensor 1 temperature heating (hereinafter referred to as a heat-up), the both air-based and CO gas sensitivity can be stable over time.

[Problems to be solved by the invention]

In the above-described device, the power consumption is usually 2 W to 4 W, and it is impossible to use it for a device that operates with a dry battery or the like, including a portable use, from the viewpoint of power consumption. In addition, depending on the burning equipment used intermittently, such as a water heater for bathroom
Even when detecting CO gas, the combustion equipment must be heated up each time it becomes in a combustion state, and the power consumption increases, so that it cannot be operated by a dry cell or the like.

Therefore, the present invention is to determine the sensor output from the semiconductor type sensor and to detect CO gas by intermittently used combustion equipment such as a bath water heater, without impairing the stability of operation It is an object of the present invention to provide a CO gas detection device that can use a dry battery or the like with low power consumption.

[Means for solving the problem]

In order to solve the above-mentioned problems, a CO gas detection device made according to the present invention detects a CO gas from a combustion device used intermittently such as a bath water heater by judging a sensor output from a semiconductor sensor. Power supply means for supplying operating power to the semiconductor sensor,
Heat-up generating means for operating the power supply from the power supply means to heat the semiconductor sensor and clean the semiconductor sensor at the start of the direct passage in which power is supplied to the semiconductor sensor by the power supply means; A temperature sensor to be detected, and power supply control means for driving the power supply means continuously for a period from a time when the combustion state of the temperature sensor is detected to a time when the detection is completed and a time from the time when the detection is completed to a predetermined time, The semiconductor type sensor is characterized in that after being cleaned by the heat-up generating means at the time of detecting the combustion state, the operating power is continuously supplied from the time of the detection to the period of the predetermined time.

(Operation)

In the above configuration, when the temperature sensor detects that the combustion device has become in a combustion state, the power supply control unit controls the power supply unit to supply operating power to the semiconductor sensor and the heat-up generation unit. I do. The heat-up generating means heats and cleans the semiconductor sensor at the start of energization of the semiconductor sensor. Thus, when CO gas is generated, the semiconductor sensor determines the sensor output and detects the CO gas. Thereafter, when the combustion state of the combustion appliance ends, the temperature sensor ends the detection of the combustion state, but the power supply means controls the semiconductor sensor to supply operating power. Therefore, even if the combustion appliance is brought into the combustion state again during the predetermined time period, the heat-up generating means does not operate, and the semiconductor sensor continues to be in the CO gas detection state.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a CO gas detecting apparatus according to the present invention, in which 1 is a semiconductor sensor, 2 is a battery circuit, 3 is a thermistor, and a temperature compensator for correcting a sensor output. Circuit, 4 is an air level determination circuit, 5 is a heat-up generation circuit that generates a heat-up based on an output from the determination circuit 4, 6 is a sensor output determination circuit, 7 is a display circuit, 8 is an alarm circuit, and 9 is a cancellation circuit. , 10 are timer circuits, and 11 is a voltage drop detection circuit for detecting a voltage drop of the battery 2. The semiconductor device 1 to the voltage drop detection circuit 11 constitute a detection device main body A.

The above-mentioned semiconductor type sensor 1 carries a noble metal such as palladium as a sensitizer on stannic oxide obtained by baking a tin salt, and mixes a suitable amount of alumina for sensitivity adjustment to obtain a sensor material. Paste the material, 0.38mm thick
And by screen printing on 3 mm square alumina chips. Further, a metal oxide heater is formed on the back surface by printing, and the obtained one is appropriately aged and used as a sensor.

The semiconductor sensor 1 is usually used at normal temperature without heating. Therefore, the battery circuit 2 is, for example, an AA alkaline battery.
× 4, so that it can be used as a portable detection device. The cancellation circuit 9 is provided to prevent the sensor output from excessively responding due to the heat-up, and prevent the sensor output determination circuit 6 from erroneously determining the generation of CO gas.

The air level determination circuit 4 determines that the sensor output increases when power is supplied from the battery circuit 2 to the sensor 1 and when the CO gas is detected, and drives the heat-up generation circuit 5 to heat the sensor 1. Let it up.

Also, the timer circuit 10 causes the sensor output to increase or decrease the determination level of the air level determination circuit 4 due to heat-up,
After the heat-up, a delay is provided so as not to heat up for a predetermined time, and the heat-up is repeatedly performed after a predetermined time when the air level of the sensor output is always equal to or higher than the determination level of the air level determination circuit 4. Things. Further, the display circuit 7 and the alarm circuit 8 are for displaying an abnormal state and alarming by a buzzer or the like when the sensor 1 detects the CO gas. It also has a function to warn when 2 drops to a predetermined voltage.

Reference numeral 12 denotes a temperature sensor for detecting a combustion state of a burning appliance such as a water heater for a bathroom, and 13 denotes a hold circuit which operates with a sensor output from the temperature sensor 12 and outputs a control signal to the battery circuit 2. is there. The hold circuit 13 is a temperature sensor
When 12 detects the combustion state of the combustion equipment, it outputs a control signal to the battery circuit 2 to supply operating power to the main body A including the semiconductor sensor 1 and the heat-up generating circuit 5, and also detects the temperature by the temperature sensor 12. The continuous combustion time of the burning appliance is accumulated, a control signal is continuously output from the end of the combustion state for a predetermined time period corresponding to the accumulation time, and the operation power is supplied from the battery circuit 2. .
The temperature sensor 12 is composed of a thermistor or the like, and is installed on, for example, fins of a water heater for a bathroom.

The hold circuit 13 includes, for example, an up / down counter and an up / down pulse generation circuit.
Detects a combustion state, the counter counts up with an up pulse from an up pulse generation circuit, and sends a control signal when the count value is "1" or more. When the combustion state ends, the counter counts down with a down pulse from the down pulse generation circuit, and when the count value becomes "0", the output of the control signal is stopped. The control signal is output for 60 minutes including that for 30 minutes.

In the above configuration, the operation is shown in FIGS.
It will be described together with the timing chart of FIG.

Phenomenon I in the figure shows a characteristic in a normal state where CO gas is not generated as shown in FIG. 4F, and phenomenon II shows a state in which CO gas is generated from the combustion appliance. First, the phenomenon I will be described. The combustion device enters a combustion state, and the temperature sensor 12 detects the time t _0.
When it is detected that the temperature is equal to or higher than a predetermined temperature (for example, 50 ° C.), the sensor output becomes H level as shown in FIG. 2 (a).
When the temperature sensor 12 goes high, the hold circuit 13 generates an up-pulse that drives the built-in up-pulse generation circuit as shown in FIG. 2B, and counts up the pulse by the built-in count. The time when the output of No. 12 is at the H level is measured.

The hold circuit 13 outputs a control signal when the output of the temperature sensor 12 becomes H level as shown in FIG. By the control signal, the detector main body A is supplied with the operating power from the battery circuit 2 as shown in FIG. The air level determination circuit 4 constantly monitors the air level, and when a predetermined level (heatup determination level) is reached, drives the heatup generation circuit 5 to heat the sensor 1 and heat up to a high temperature (for example, 400 ° C.). I do.

Here, when power is supplied to the main body A at time t ₀ , the air level rises, so that the air level determination circuit 4 exceeds the heat-up determination level, and the air-level determination circuit 4 causes the heat-up generation circuit 5 to operate for several tens of seconds (for example, 60 seconds). Operate semiconductor sensor 1
Is heated, and the sensor 1 is cleaned. As a result, the output of the semiconductor sensor 1 temporarily rises as shown in FIG. 5E, but at this time, the operation of the canceling circuit 9 does not generate a CO gas detection output from the sensor output determination circuit 6. After that, it rapidly decreases and returns to the original air level.

After time t ₀ , the combustion of the combustion equipment ends, and the temperature sensor 12
When the detected temperature of is at time t ₁ to a predetermined value or less, the output of the temperature sensor 12 is at the L level, the hold circuit 13 accumulates the combustion state time t ₀ -t ₁ the count value of the counter (Measurement Assuming that this time is, for example, 30 minutes, the counter counts down with a down pulse from the down pulse generation circuit, and then continuously outputs a control signal for 30 minutes until the count value becomes “0”. Output. That is, if t ₀ −t ₁ is 30 minutes, a control signal is output for 60 minutes as shown in FIG. 2 (c), and the battery circuit 2 is continuously operated for 60 minutes as shown in FIG. 2 (d). Operation power is supplied to the main body A such as the sensor 1.

Therefore, combustion appliances during this 60 minutes is again the combustion state, for example, even if a temperature sensor 12 is the H level again at FIG. 2 (a) time t ₂ of (t ₁ after 20 minutes), the semiconductor Since operation power is continuously supplied to the expression sensor 1 from time t ₀ , the heat-up operation by the heat-up generation circuit 5 at the start of energization is not performed.

The counter of the hold circuit 13 counts up again based on the H level, and starts the accumulation operation. Thereby, the power consumption of the battery circuit 2 can be controlled.

The combustion state is completed again at time t ₃ of 5 minutes after t _2,
When the detection output of the temperature sensor 12 becomes the L level, the hold circuit 13 accumulates the combustion state time of t ₂ -t _3, then the counter counts down. Becomes more combustion state at time t ₄ after 20 minutes, when ends at time t ₅ after 5 minutes, the hold circuit 13 accumulates the t ₄ -t ₅ hours, the counter counts up during the time, the time Exit the combustion state at t ₅ and the countdown counter of time t ₅ hereafter hold circuit 13 is also the count value is further continuously until "0" a predetermined time (10 minutes) operating power to the semiconductor sensor 1 is Supplied. That is, from when the combustion state at time t ₀ as shown in the second diagram, is 30 minutes combustion state, the combustion again 5 minutes after 10 minutes, if the further combustion 5 minutes after 20 minutes, 80 minutes from t ₀ time t ₆ to exit the supply of operating power after, until t ₀ -t ₆ is operating power to the main body a is supplied continuously.

Therefore, assuming that, for example, a water heater for a bathroom is used as a burning appliance, the combustion state is long at the start of energization (t ₀ −t ₁ hour in FIG. 2), and then intermittently short (t ₀ −t _{1 in} FIG. 2).
(t ₂ −t ₃ , t ₄ −t ₅ hours) In the case of overtaking, the semiconductor sensor 1 heats up only at the start of energization, and thereafter the main body A is continuously in the CO gas detection state. Since no heat-up is performed at the time of chasing, power consumption is suppressed.

The phenomenon II shows the case where CO gas is generated, when energized at time t ₀ is started first heat up the semiconductor sensor 1 as described above, to clean the semiconductor sensor 1,
CO gas in the event the second diagram (3) the sensor output increases as the heat-up generator 5 becomes the heat-up determination level than at time t ₇ to heat up the semiconductor sensor 1 is operating. The semiconductor sensor 1 is cleaned by this heat-up, but the sensor output is still CO
Since the temperature rises due to the presence of gas and exceeds the heat-up determination level, the timer circuit 10 is activated by the output from the heat-up generation circuit 5, and the heat-up is repeatedly performed in a short time of about 1 to 2 minutes, and the sensor output When the determination circuit 6 at time t ₈ reaches a predetermined CO gas judging level, notifying the occurrence of the CO gas to the outside by driving the alarm circuit 8 and a display circuit 7.

The hold circuit 13 is constituted by an RC integration circuit, which performs a charging operation during a combustion state and performs a discharging operation during a combustion termination state. The circuit 2 may supply operating power.

FIG. 3 shows another embodiment of the present invention, in which a timer circuit 14 is provided instead of the hold circuit 13 in FIG.
The output of the timer circuit 14 and the output of the temperature sensor 12 are supplied to 13, and the other configuration is the same as that of FIG.

After the temperature sensor 12 detects the temperature equal to or higher than the predetermined temperature, the timer circuit 14 starts the operation when the temperature becomes equal to or lower than the predetermined temperature, and continues the operation for a predetermined time (for example, 15 minutes). Upon detection, it is reset even within the predetermined time. The battery circuit 2 receives a control signal from the temperature sensor 12 when the temperature sensor 12 detects a predetermined temperature or higher, and receives a control signal from the timer circuit 14 when the timer circuit 14 is operating. Can be

In the above configuration, the operation is shown in FIGS.
This will be described together with the timing chart of FIG. In the normal state of the phenomenon I, burner is a combustion state, when the temperature detected by the temperature sensor 12 at time t ₀ as shown in the fourth diagram (a) becomes equal to or higher than a predetermined temperature, the output of the temperature sensor 12 becomes H level, A control signal is supplied to the battery circuit 2 as shown in FIG. Thereby, the semiconductor sensor 1 is heated up and cleaned by the heat-up generating circuit 5.

When the detected temperature of the subsequent time combustion state has passed 30 minutes ended t ₁ temperature sensor 12 is below a predetermined value, the output of the temperature sensor 12 becomes L level, the timer circuit 14 as shown in FIG. (B) is Operate for a predetermined time (for example, 15 minutes). By this timer output, a control signal is continuously supplied to the battery circuit 2 as shown in FIG. 4C, and the main unit A is continuously supplied with the operation power. During the operation of the timer circuit 14, the combustion apparatus becomes in a burning state again, and at time t ₂ (10 minutes after t ₁ ), the detection output of the temperature sensor 12 becomes H level. At the same time as the circuit 14 is reset, the control signal is continuously supplied to the battery circuit 2 and the operation power is supplied to the main unit A.

Hereinafter, when the combustion state occurs in 5 minutes of t ₂ -t _{3 and} in 5 minutes of t ₄ -t ₅ 10 minutes after t ₃ , the battery circuit 2 is controlled by the output from the temperature sensor 12 during the period. Signal supplied, t ₃
During the -t ₄ is the control signal is supplied at the output than the timer circuit 14. When the combustion state at time t ₅ is completed, the operation at time t ₆ after the timer circuit 14 is activated a predetermined time ends.

Therefore, the timing in the combustion state as described above is repeated, operation power is supplied continuously to FIG. 4 (c) of as t ₀ body A than 75 minutes the battery circuit 2 up -t _6.

2D and 2E show the detection output of the semiconductor sensor 1 and the CO gas concentration, respectively.
Same as (f). The same applies to the case of CO gas generation of the phenomenon II as shown in FIG.

Further, in the normal state of the phenomenon I of each embodiment, if the air base becomes higher than the heat-up determination level after the start of energization, the air-level determination circuit 4 determines this and operates the heat-up generation circuit 5 to operate the semiconductor sensor. Heat up 1 and clean.

Further, in each of the above embodiments, for example, when using AA alkaline batteries for the battery circuit 2 and performing the energization start operation twice a day to heat up and operating the main body A for one hour a day, about 380 It can be used for days.

(Effect)

As described above, according to the present invention, when the combustion state of the combustion appliance ends, the temperature sensor ends the detection of the combustion state, but the power supply means controls the semiconductor sensor to supply operating power to the semiconductor sensor. However, even if the combustion apparatus becomes in a combustion state again during the predetermined time period, the heat-up generating means does not operate and the semiconductor sensor is continuously in the CO gas detection state. The power consumption can be reduced without reducing the detection sensitivity of the CO gas.

The device according to the invention can also be used in places without a commercial power supply and can be implemented with only a few additions to the existing detection device body.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a CO gas detecting device according to the present invention, FIG. 2 is a diagram showing a timing chart of the output of each unit in the device of FIG. 1, and FIG. 3 is another embodiment of the present invention. FIG. 4 is a diagram showing a timing chart of each unit in the apparatus shown in FIG. 3, FIG. 5 is a view showing a conventional apparatus, and FIG. 6 is a diagram showing a sensor temperature and a sensor output in the apparatus shown in FIG. FIG. 7 is a diagram showing another conventional device, and FIG. 8 is a diagram showing sensor temperature and sensor output characteristics in the device of FIG. DESCRIPTION OF SYMBOLS 1 ... Semiconductor sensor, 2 ... Battery circuit (power supply means), 5 ... Heat-up generation circuit (Heat-up generation means), 12 ... Temperature sensor, 13 ... Hold circuit (Power supply control means), 14 Timer circuit (power supply control means).

Claims (1)

(57) [Claims] 1. A CO gas detecting device for judging a sensor output from a semiconductor type sensor to detect CO gas from an intermittently used burning appliance such as a bath water heater. A power supply means for supplying power; and a heat-up operation for heating the semiconductor sensor by heating with the power supply from the power supply means and cleaning the semiconductor sensor when power is supplied to the semiconductor sensor by the power supply means. Means, a temperature sensor for detecting a combustion state of the combustion appliance, and a drive for continuously driving the power supply means during a period from the detection of the combustion state of the temperature sensor to the end of the detection and a period from the end of the detection to a predetermined time. Power supply control means for causing the semiconductor type sensor to be cleaned by the heat-up generating means at the time of detection of the combustion state, and thereafter performing the predetermined time after the detection. Operation power continuously until the period has to be supplied, CO gas detecting device, characterized in that.