JPH08101155A - Co gas sensing device for gas combustion device - Google Patents

Abstract

PURPOSE: To provide a CO gas sensing device which is for a gas combustion device, presents a high safety and reliability, can remove oil fumes and/or sulfides likely to generate drop of the sensitivity and a zero-point drift while ill influence upon the lifetime of a sensing element and unstableness due to transient response are suppressed, and can monitor CO gas with high accuracy. CONSTITUTION: A control means 12b permits a driving means 11 to heat a sensing element 1a of a CO sensor 1 to the sensing temp. upon heat-up to the first temp. A judging means 12d senses CO gas by the sensing output of the CO sensor 1 and the zero-point reference value in a memory means 12a set by a setting means 12c. When a sensing means 12e senses a difference over a specified level between the sensing output and the zero-point reference value, heat-up to the second temp. is conducted, A new zero-point reference value is set in response to sensing of zero-point drift after heating to the second temp. Otherwise, the second temp. heat-up is performed when the combusting frequency counted by a counting means 12f is a specified value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CO gas detector for a gas combustor such as a water heater, and more particularly to a predetermined safety device for detecting an abnormal state by measuring the concentration of carbon monoxide in the exhaust gas of the water heater. The present invention relates to a CO gas detection device for a gas combustion device, which is operated.

[0002]

2. Description of the Related Art Conventionally, indoor water heaters (FE type)
Such gas combustion devices are known, and in this type of gas combustion device, the concentration of combustible gas such as carbon monoxide in exhaust gas is measured using a so-called contact combustion type detection element, and a predetermined safety device is installed. A CO gas detector is provided for activation.

For example, the FE type water heater using an AC100V power source is provided with a CO detector having a catalytic combustion type detection element arranged at the exhaust port of the main body, and the CO detector is exhausting air. The abnormal state is detected by measuring the concentration of carbon monoxide contained in, and the gas supply pipe leading to the burner is shut off by a solenoid valve as a safety device.

That is, as shown in FIG.
In the O detector 1, a sensing element 1a arranged at an exhaust port portion that can contact exhaust gas constitutes a bridge circuit together with a temperature compensating comparison element (not shown), a fixed resistor and a movable resistor, and the sensing element described above. When 1a comes into contact with the exhaust gas, heat is generated according to the carbon monoxide concentration in the exhaust gas, and the resistance value changes, which destroys the equilibrium state of the bridge circuit and a voltage of a magnitude corresponding to the degree of unbalance is detected output Vs. Is output as. Then, when the detection output Vs exceeds a preset set value Vr, it is determined that the carbon monoxide concentration in the exhaust gas is in a dangerous state, an alarm signal is output to shut off the gas supply source, and It is designed to prevent carbon poisoning and poisoning accidents. The sensing element is generally formed by forming a platinum wire having a wire diameter of 20 to 30 μm in a coil shape, and forming a bead shape of alumina on which a noble metal catalyst is supported on the coil and a comparison element formed by only supporting alumina. It has a structure in which a protective cap is attached to this.

In this type of CO gas detection device, the fixed alarm level Vr which is predetermined as described above is compared with the detection output Vs. Therefore, the detection output Vs is the alarm level Vr as a premise. It is necessary to surely set the 0-point reference value in the state where carbon monoxide is not detected, which is the criterion for determining whether or not it has exceeded the limit. The bridge circuit is adjusted so as to be in a balanced state by adjusting the variable resistance of (1), and the zero point reference value is set.

By the way, since the detection element 1a included in the CO detector 1 is arranged at the exhaust port portion in the exhaust gas flow path of the water heater, the surface of the detection element 1a is exposed to the exhaust gas. Various contained substances are adsorbed, and the element adsorbed substance reduces the detection sensitivity of the detection element 1a for CO gas. Therefore, the element temperature is heated up to 350 to 400 ° C for a short time to remove the adsorbed elements when the detector power supply that is interlocked with the ignition of the water heater is turned on, and then the element temperature is set to around 200 ° C in the normal use state. I try to heat it.

Further, in the catalytic combustion type detecting element 1a of the CO detector 1 in the CO gas detecting device,
The resistance value may change due to aging and the like in a state where carbon monoxide is not detected, and in such a case, it serves as a criterion for determining whether or not the detection output Vs exceeds the alarm level Vr. The 0-point reference value becomes erroneous when carbon monoxide is not detected, which causes a detection output Vs including a significant error and a predetermined alarm level Vr.
And the actual carbon monoxide concentration is at the alarm level Vr, but the alarm level Vr at the detector side.
There is a risk that a predetermined safety device will not operate at all, resulting in a dangerous state.

Therefore, as proposed in Japanese Utility Model Laid-Open No. 5-90148, the output of the CO detector 1 when the water heater is extinguished is stored as a 0-point reference value, and the stored detection output is stored. As a reference, a detection output when the water heater is ignited is monitored, and a predetermined alarm operation is performed when the detection output becomes equal to or higher than a predetermined output for a predetermined concentration of CO gas.

[0009]

It is considered that the above-mentioned heat-up for removing the adsorbed material of the element is sufficient under normal use conditions. However, when the water heater is left for a long period of time, oil smoke or the like may adhere to the detection element, or sulfide may temporarily adhere during use, and these oil smoke and S (sulfur) -based substances are high in content. When it is adsorbed to the sensing element 1a without decomposing unless it is at a temperature, the sensing sensitivity of the sensing element is lowered, or the 0-point reference value of the CO detector 1 is changed.
So-called zero point drift will occur. For this zero-point drift, it is possible to use the method proposed in the above-mentioned publication, but this proposed method does not correct the sensitivity.

Further, as a method for preventing the decrease in sensitivity,
A method of raising the element temperature at the time of heat-up can be easily considered, but in the case of a water heater that is used a lot and is expected to ignite about 100,000 times, every time the CO detector is turned on with ignition. When heat-up is performed at a high temperature, heat and current at this time may adversely affect the life of the sensing element 1a, and instability due to a transient response for each heating-up of the sensing element is accompanied by this high temperature. If the heat up is performed every time the power is turned on, there is a problem in monitoring the CO gas concentration with high accuracy and enhancing safety and reliability.

Therefore, in view of the above points, the present invention has an adverse effect on the life of the sensing element, or an unstableness due to a transient response, of an adsorbent substance which decomposes at a high temperature which causes a decrease in sensitivity and a change in the zero point reference value. It is intended to provide a CO gas detection device for a gas combustion device, which is highly safe and highly reliable, by which CO gas concentration can be monitored with high accuracy by suppressing the generation of dust as much as possible. To do.

[0012]

In order to achieve the above object, a CO gas detection apparatus for a gas combustion apparatus according to the present invention has a gas combustion apparatus in a combustion state as shown in the basic configuration diagram of FIG. 1 (a). CO detector 1 having a catalytic combustion type detection element 1a for detecting CO gas contained in the exhaust gas discharged from the gas combustion apparatus when heated to a detection temperature when
And a CO detector driving means 11 for driving the CO detector
And controlling the CO detector driving means to heat up the detection element to a first temperature higher than the detection temperature for a certain period of time every time the gas combustion device enters a combustion state, and heat for the certain period of time. After the up, the drive control means 12b that keeps the detection element heated to the detection temperature while the gas combustion apparatus is in the combustion state, the storage means 12a that stores a 0-point reference value for generating an alarm, and the detection The detection output of the CO detector when the element is heated to the detection temperature and the gas combustion device is not in the combustion state is stored in the storage means as a 0-point reference value for generating an alarm. Setting means 12c for setting a 0-point reference value, and the detection output of the CO detector when the gas combustion device is in a combustion state is monitored with reference to the 0-point reference value stored in the storage means, and this detection is performed. In a CO gas detection device for a gas combustion device, the CO combustion gas detecting device is provided with a determination means 12d for determining that the force is equal to or greater than a predetermined value for a predetermined concentration of CO gas and generating an alarm. A zero-point drift detection means 12e for detecting that the difference between the detection output of the CO detector and the zero-point reference value becomes a predetermined value or more each time the non-combustion state is reached, and the drive control means comprises: The CO detector driving means is controlled according to the detection by the zero-point drift detecting means, and the second temperature is higher than the first temperature and sufficiently high to remove deposits such as oil smoke and sulfide that decompose at high temperature. It is characterized in that the sensing element is heated to a temperature for a predetermined time.

In the configuration shown in FIG. 1A, the CO detector driving means 11 drives the CO detector 1 under the control of the drive control means 12b. The catalytic combustion type detection element 1a of the CO detector 1 is heated to a detection temperature when the gas combustion device is in a combustion state and detects CO gas contained in the exhaust gas discharged from the gas combustion device. The CO detector driving means 11 heats the detection element to a first temperature higher than the detection temperature for a certain period of time each time the gas combustion device enters a combustion state, and after the certain period of heat-up, the gas combustion device burns. The sensing element is continuously heated to the sensing temperature while in the state. The zero point reference value for generating the alarm stored in the storage means 12a is set by the setting means 12c, and CO detection is performed when the detection element is heated to the detection temperature and the gas combustion device is not in the combustion state. This is the detection output of the container. The determination means 12d monitors the detection output of the CO detector when the gas combustion device is in a combustion state with reference to the 0-point reference value stored in the storage means, and this detection output is predetermined for a predetermined concentration of CO gas. It is judged that the value exceeds the specified value and an alarm is issued.

The 0-point drift detection means 12e detects that the difference between the detection output of the CO detector and the 0-point reference value becomes a predetermined value or more each time the gas combustion device changes from the combustion state to the non-combustion state. The drive control means controls the CO detector drive means in response to this detection to a second temperature higher than the first temperature and high enough to remove deposits such as oil smoke and sulfide that decompose at high temperatures. The sensing element is heated up for a predetermined time. Therefore, even if the detection element is heated to the first temperature higher than the detection temperature for a certain period of time every time the gas combustion apparatus enters the combustion state, and the zero point drift of the predetermined value or more occurs, the first temperature By heating up to a higher second temperature, the deposits that decompose at high temperature, such as oil smoke and sulfide, which cause zero-point drift, are removed, and the sensitivity is restored and the zero-point drift is eliminated. Be seen.

The setting means 12c is in a state in which the detection element is heated to the detected temperature after the detection by the zero-point drift detection means immediately after the detection element is heated to the second temperature. Moreover, the detection output of the CO detector when the gas combustion device is not in a combustion state is stored in the storage means as a new zero point reference value.

Further, the sensing element is heated to the second temperature to zero.
Even if the deposits that decompose at high temperature, such as oil smoke and sulfides that cause point drift, are removed, if there is still 0 point drift detected by the 0 point drift detection means immediately after that, the setting means 12c Since the detection output of the CO detector when the detection element is heated to the detection temperature and the gas combustion device is not in the combustion state is stored in the storage means as a new 0-point reference value, 0 other than the adhered matter is stored. The cause of point drift is also eliminated.

The CO gas detector for a gas combustion apparatus, which is made according to the present invention to achieve the above object, has a detection temperature when the gas combustion apparatus is in a combustion state, as shown in the basic configuration diagram of FIG. 1 (b). A CO detector 1 having a catalytic combustion type detection element 1a for detecting CO gas contained in the exhaust gas which is heated and discharged from the gas combustion device, and CO detector drive means 11 for driving the CO detector. Controlling the CO detector driving means to heat the sensing element to a first temperature higher than the sensing temperature for a certain period of time each time the gas combustion device enters a combustion state, and heat up for the certain period of time. After that, the drive control means 12b keeps heating the detection element to the detection temperature while the gas combustion apparatus is in the combustion state.
And a storage means 12a for storing a 0-point reference value for generating an alarm, and the CO detector when the detection element is heated to the detection temperature and the gas combustion device is not in the combustion state. Detection output of 0 to generate an alarm
Setting means 12c for setting the 0 point reference value stored in the storage means as the point reference value, and the CO detection when the gas combustion apparatus is in the combustion state with the 0 point reference value stored in the storage means as a reference Determination means 12 for monitoring the detection output of the container and for determining that the detection output has exceeded a predetermined value for a predetermined concentration of CO gas and for issuing an alarm.
In the CO gas detection apparatus for a gas combustion apparatus, the counter unit 12f counts each time the gas combustion apparatus changes from a combustion state to a non-combustion state, and the drive control unit has a predetermined value or more by the counting means. The CO detector driving means is controlled according to the count of the detection element, and the detection element is set to a second temperature higher than the first temperature and high enough to remove deposits such as oil smoke and sulfide that decompose at high temperature. Is heated for a predetermined time.

Further, in the configuration shown in FIG. 1B, the counting means 12f counts each time the gas combustion device changes from the combustion state to the non-combustion state, and the drive control means in accordance with the count of the predetermined value or more by the counting means. Controls the CO detector driving means to heat up the sensing element for a predetermined time to a second temperature which is higher than the first temperature and is high enough to remove deposits that decompose at high temperatures such as oil smoke and sulfides. There is. Therefore, assuming that the number of times the gas combustion device is in the combustion state exceeds a predetermined value, it is assumed that the zero-point drift occurs due to the deposits such as oil smoke and sulfides that decompose at high temperatures. By heating up at a second temperature higher than the temperature of, the deposits that decompose at high temperature, such as oil smoke and sulfides that cause zero-point drift, are removed, and the sensitivity is restored and the zero-point drift is eliminated. Is done.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an embodiment of a CO gas detector for a gas combustion apparatus according to the present invention applied to a gas combustion apparatus of a gas water heater, and a burner 5 is required at a lower end portion of the water heater main body 3. A fan 4 for supplying air is provided, and the air from the fan 4 and the gas from a gas supply pipe (not shown) are sent to the burner 5 in the main body 3 to burn the gas. . Then, in the heat exchanger 6 arranged above the burner 5, the water sent from the water supply pipe (not shown) is boiled to hot water of a predetermined temperature. In addition, at the upper end of the main body 3,
An exhaust port 7 is provided so that the combustion gas containing combustible gas such as carbon monoxide from the burner 5 is exhausted. Further, at the upper end of the main body 3 at a position where the combustion gas passes, C having the same structure as the conventional one is used.
A catalytic combustion type detection element 1a of the O detector 1 is provided.

Further, as shown in FIG. 3, a CO detector drive circuit 11 is connected to the CO detector 1,
The drive circuit 11 is connected to a water heater control circuit 12 including a microcomputer (CPU) having a built-in memory 12a. Further, the water heater control circuit 12 is connected to a flow sensor 13 provided in the water supply pipe, a reset switch 14 for releasing an alarm, an alarm buzzer 15, a fan drive circuit 16, Burner control circuit 17 and solenoid valve 18 provided in the gas supply pipe
A solenoid valve drive circuit 19 for driving the is connected. In the figure, reference numeral 20 is a power supply circuit that converts AC 100 V supplied via the AC 100 V power supply line 21 into a stabilized DC voltage and supplies the stabilized DC voltage to each unit, 22 is a power supply control line, and 23 is a signal line.

By the way, a CO detector 1 having a catalytic combustion type detection element 1a is used for detecting a sulfide such as SO ₂ .
When continuously tested in the atmosphere containing each ppm, 0 point output and CO output which are the detection output of CO detector 1
The sensitivity to the mixed gas of 3000 ppm + H ₂ 1500 ppm changes with the elapsed days as shown in FIGS. 4 (a) and 4 (b). As is clear from FIG. 4, both the 0-point output and the sensitivity tend to decrease by the SO _x (sulfide) test, and when this is graphed by comparing the 0-point drift width and the sensitivity change rate, FIG. It turns out that there is a close relationship between the two. That is, it can be seen that the sensitivity decreases as the zero-point drift width increases.

In the CO detector 1 of the sample whose sensitivity has been lowered by the sulfide test as described above, when the detecting element is heated up at a temperature of 350 to 400 ° C. as in the conventional case, FIGS. ), As indicated by white circles,
Both point output and sensitivity have not been improved at all. On the other hand, when the sensing element according to the present invention is heated up at a temperature of, for example, 550 ° C. or higher for 3 minutes, both the 0 point and the sensitivity may be returned as shown by black circles in FIGS. 6 (a) and 6 (b). Recognize. From the above, even if an adsorbate that cannot be desorbed under the conventional heat-up conditions, the sensitivity is restored by the desorption of the adsorbate by raising the element temperature to the above-mentioned temperature of 550 ° C. or more during heat-up. I understand.

The timing for performing the high temperature heat-up is 0 and the detection output when the gas combustion device is not in the combustion state and the CO detector 1 is heated to the detection temperature.
It is sufficient that the 0-point drift voltage, which is the difference from the point reference value, becomes 0.5 V at which the sensitivity decreases by 30% as shown in FIG.

In the CO gas detector of FIG. 3, AC
When you plug the outlet into a 100V power source, the power circuit 21
Power is supplied to each part of the water heater main body 3 via the. When the power is turned on, the CPU of the water heater control circuit 12 is activated to apply a control signal to the CO detector drive circuit 11 via the power supply control line 22. In response to this, the CO detector drive circuit 11 detects CO. An operating power supply is supplied to the container 1 to supply a heating current for heating the sensing element 1a to a sensing temperature of, for example, about 200 ° C. CPU of the water heater control circuit 12
Also starts a built-in timer that sets a predetermined time. When the timer measures a predetermined time, C
By determining that the bridge circuit of the O detector 1 is stable, the detection output Vs input at that time via the signal line 23 is read, and this is stored in, for example, the RAM of the memory 12a in the water heater control circuit 12. , A 0-point reference value V ₀ for issuing an alarm is set. As a result, the zero point reference value is set when the burner 5 is not in a burning state and carbon monoxide is not being generated. After setting the 0-point reference value as described above, the CPU of the water heater control circuit 12 applies a control signal to the CO detector drive circuit 11 via the power supply control line 22, and in response to this, the CO The detector drive circuit 11 is CO
The supply of operating power to the detector 1 is stopped.

In this state, the water heater control circuit 12
Is based on a signal from the flow sensor 13, the user determines whether water is flowing by opening a water tap (not shown) of the water heater main body 3, and when it is determined that water is flowing, the CO detector drive circuit 11 A control signal is applied to the power supply via the power supply control line 22. By applying this control signal, CO
As shown in FIG. 7, the detector drive circuit 11 includes a detector element 1
After a heat-up current for heating a to a first temperature of, for example, about 350 to 400 ° C. for a predetermined time is passed, a heating current that keeps heating to the detection temperature of about 200 ° C. is passed. Around this time, the water heater control circuit 12 applies a control signal to the burner control circuit 17 to ignite the burner 5 and applies a control signal to the fan drive circuit 16 to apply the control signal to the fan 4
To rotate. As a result, the air from the fan 4 and the gas from the gas supply pipe are combusted in the burner 5, and in the heat exchanger 6 arranged above the burner 5, the water sent from the water supply pipe is It is designed to be boiled in hot water of a predetermined temperature.

After that, the water heater control circuit 12 turns on the flow
The signal from the sensor 13 allows the user to
When it is determined that the plug is closed, the burner control circuit 17
Apply a control signal to extinguish the burner 5 and
The control signal is applied to the drive circuit 16 to stop the fan 4.
After that, the detection output V from the CO detector 1_STo read.
After that, the water heater control circuit 12 uses the CO detector drive circuit 11
To the control signal via the power supply control line 22
The CO detector drive circuit 11 supplies power to the CO detector 1.
Supply of power is stopped and the detection element 1a is detected at about 200 ° C
Stop the action of heating to temperature. Then read this
Detection output V_SAnd 0 point reference value V₀Difference V _S-V₀Is an example
For example, when it is determined that the voltage is 0.5 V or higher, the water heater control
The circuit 12 supplies a power supply control circuit to the CO detector drive circuit 11.
Applying a control signal via IN 22 to drive the CO detector
The circuit 11 causes the sensing element 1a to reach a second temperature of, for example, about 550 ° C.
Each time it heats up for a predetermined time, for example, 120 mA
The heat-up current of 1 is applied for a fixed time of 3 minutes, for example.
The difference V by the water heater control circuit 12_S-V₀Is 0.
When it is determined that the voltage is not 5V or higher,
Wait for the faucet of the main body 3 to be opened again. Also, water heater control
Used by the circuit 12 by the signal from the flow sensor 13.
When a person determines that the faucet is not closed, CO detection
The carbon monoxide concentration is monitored by the detection output Vs from the vessel 1.
In addition, an alarm is issued in the case of an abnormal condition where the concentration exceeds a certain level, and
The burner 5 is closed by shutting off the solenoid valve 18 provided in the gas supply pipe.
To extinguish the fire.

That is, in detail, the alarm reads the detection output Vs from the CO detector 1, takes the difference Vs-V ₀ between the read detection output Vs and the 0-point reference value V _0, and the difference Vs-V _0, as compared with the alarm level Vr stored predetermined, for example, in RAM of the memory 12a in the water heater control circuit 12 so as to determine its magnitude. Then, when direction of the difference Vs-V ₀ is large, it actuates an alarm buzzer 15, so as to extinguish the burner 5 by blocking the electromagnetic valve 18 provided in the gas supply pipe.

After that, the reset switch 1 for releasing the alarm
When it is determined that 4 has been operated, the alarm buzzer 15
Water that has stopped operating and has not been boiled to the prescribed temperature
Will continue to flow and the reset switch 14 will be operated.
If it is determined that the warning buzzer 15 is not activated, the alarm buzzer 15 is activated.
It keeps moving. Also, the difference Vs-V ₀
When it is determined that is lower than the alarm level Vr,
The combustion of the burner 5 is maintained.

In the present embodiment, when the burner 5 burns, the combustion gas emits the CO gas provided in the water heater main body 3.
It comes into contact with the detection element 1a of the detector 1, whereby the concentration of carbon monoxide in the exhaust gas is monitored.

Therefore, in the present embodiment, when the water heater main body 3 is powered on, a new 0-point reference value V ₀ is set in a state including the deviation of the 0-point reference value described above, and detection is performed. The difference Vs− between the output Vs and the new zero point reference value V ₀
Since V ₀ is compared with the alarm level Vr corresponding to a predetermined dangerous concentration of carbon monoxide, the carbon monoxide concentration can be monitored with high accuracy.

Of course, the contact type detection element 1 of the CO detector 1 in a state where carbon monoxide is not detected due to aging or the like.
Even if the resistance value of “a” changes and then the resistance value of the sensing element 1 a surely changes according to the carbon monoxide concentration, the outlet of the water heater main body 3 is periodically changed. By removing and inserting the power source and periodically turning on the power source, a new 0 is added in a state including the secular change of the detection element 1a in the state where carbon monoxide is not detected.
Since the point reference value V ₀ is set, the carbon monoxide concentration can be monitored with high accuracy without being affected by the aging of the sensing element 1a.

Further, when oil smoke or the like adheres to the detection element 1a when the water heater main body 3 is left for a long time, or when sulfide is temporarily adhered to the detection element 1a while the water heater main body 3 is in use, CO detection is performed. The sensitivity of the device 1 is lowered or the 0-point reference value is deviated, and the detection output Vs including an error is output. Even in such a case, when the difference Vs−V ₀ between the 0-point reference value V ₀ and the detection output Vs is equal to or larger than a predetermined value of 0.5 V, for example,
Since the oil fumes and sulfides are removed by heat-up at high temperature, the CO detection sensitivity is maintained, and the 0-point reference value V ₀ for issuing an alarm is restored. Concentration can be monitored with high accuracy,
The safety and reliability of the gas combustion device can be significantly improved.

8 and 9 which show the details of the operation of the combustible gas detection device outlined above according to a predetermined program by the CPU constituting the water heater control circuit 12.
This will be described below with reference to the flowchart of FIG.

The CPU constituting the water heater control circuit 12 is
When the power supply of the water heater main body 3 is turned on by inserting an outlet into the AC100V power supply, the operation is started, and in the first step S1, the CO detector drive circuit 11 is first operated.
Output a control signal. In response to the input of the first control signal, the CO detector drive circuit 11 supplies an operating power to the CO detector 1 to supply a heating current for heating the detection element 1a to a detection temperature of about 200 ° C., for example. Then step S2
Then, the timer that sets a predetermined time is started. This timer is configured by using a predetermined area in the memory 12a, and data incremented every unit time is written in the predetermined area.

After that, the process proceeds to step S3, and it is determined whether or not the timer time has elapsed depending on whether or not the data has reached a predetermined value. If this determination is YES, it is determined that the bridge circuit of the CO detector 1 is stable. Next step S4
At, the detection output Vs is read. Then step S5
In step S4, the detection output Vs read in step S4 is stored in a predetermined area of the memory 12a in the water heater control circuit 12, so that the alarm 0 is generated.
The point reference value V ₀ is set. When the setting of the 0-point reference value V ₀ is completed, the process proceeds to step S6 to output the second control signal to the CO detector drive circuit 11. The input of the second control signal causes the CO detector drive circuit 11 to stop the supply of operating power to the CO detector 1. Due to the above, the burner 5 is not in a burning state and is in a state where carbon monoxide is not generated.
The point reference value is set.

After that, the process proceeds to step S7, where it is determined by the signal from the flow sensor 13 whether or not the user has opened the water tap (not shown) of the water heater main body 3 and the water has flowed. If YES, that is, if water is flowing, the process proceeds to step S8 to output the third control signal to the CO detector drive circuit 11. By applying this control signal, the CO detector drive circuit 11 applies a heat-up current that heats the sensing element 1a to a first temperature of, for example, about 350 to 400 ° C. for a predetermined time, and then detects the sensing temperature of about 200 ° C. Apply a heating current to continue heating.
In the next step S9, the burner 5 is ignited, and in the next step S1, the fan 4 is rotated. As described above, the air from the fan 4 and the gas from the gas supply pipe are combusted in the burner 5, and in the heat exchanger 6 arranged above the burner 5, the water sent from the water supply pipe is set to a predetermined value. It is designed to be boiled in hot water.

Next, in step S11, the signal from the flow sensor 13 is used to determine whether or not the user has stopped the water by closing the faucet of the water heater main body 3, and when this determination is YES. That is, when the water is stopped, the burner 5 is extinguished in the next step S12,
Further, in the next step S13, the fan 4 is stopped. After that, the process proceeds to step S14, where the detection output Vs of the CO detector 1 is read. After that, the process proceeds to step S15, where the second control signal is output to the CO detector drive circuit 11 to stop the power supply to the CO detector 1 by the CO detector drive circuit 11, and the detection element 1a is set to about 200. Stop the operation of heating to the detection temperature of ° C. In the next step S16, the difference between the read detection output Vs and the 0-point reference value V ₀ set in step S5 is calculated.

Then, the process proceeds to step S17, where the above
Difference Vs-V calculated in step S16₀But predetermined
Stored in a predetermined area of the memory 12a, for example 0.5V
Is greater than or equal to the predetermined value. This step S
When the determination at 17 is YES, that is, Vs-V₀> 0.
If it is 5, proceed to step S18 to drive the CO detector.
The fourth control signal is output to the driving circuit 11 to drive the CO detector.
The moving circuit 11 causes the detection element 1a of the CO detector 1 to output 120
Apply a heating current of mA for 3 minutes to detect element 1a at 550 ° C
Heat to. This reduces sensitivity and
0 reference value V ₀Removal of deposits that are changing
Be done. If the determination in step S17 is NO,
Wow, Vs-V₀If it is not> 0.5, the sensitivity is lowered.
0 point reference value V₀Remove the deposits that change
If it is not necessary, the process returns to step S7.

The determination in step S11 is NO.
When it is determined by the signal from the flow sensor 13 that the user has not closed the faucet, the process proceeds to step S20, where the carbon monoxide concentration is monitored by the detection output Vs from the CO detector 1 to determine the predetermined concentration. In the above abnormal state, an alarm is issued, and an alarm process is performed to shut off the solenoid valve 18 provided in the gas supply pipe to extinguish the burner 5.

That is, in the alarm process of step S20, as shown in the flowchart of FIG. 9, the detection output Vs from the CO detector 1 is read in the first step S20a, and the read sensor output is read in the next step S20b. The difference Vs−V ₀ between Vs and the 0-point reference value V ₀ set in step S5 is calculated.
Then the difference Vs-V ₀ calculated at step S20b proceeds to step S20c is predetermined, for example, whether greater than the warning level Vr stored in a predetermined area of the memory 12a in the water heater control circuit 12 judge. When the result of this determination is YES, that is, the difference Vs−V ₀
Is larger, the process proceeds to step S20d to activate the alarm buzzer 15, and then in step S20e, the solenoid valve 18 provided in the gas supply pipe is shut off to burner 5
Extinguish the fire.

After that, the process proceeds to step S20f, and it is determined whether or not the reset switch 14 for releasing the alarm is operated. If the determination is YES, the process proceeds to step S20g to stop the operation of the alarm buzzer 15 and then the above steps. Return to S7. When the determination in step S20f is NO and the reset switch 14 is not operated, the process returns to step S20d and the determination in step S20g is YES.
Since steps S20d to S20f are repeated until S is reached, the alarm buzzer 15 continues to operate. When the determination in step S20c is NO,
That is, when the difference Vs-V ₀ is smaller than the warning level Vr, the process returns to step S11, and combustion of the burner 5 is maintained.

In the present embodiment, when the burner 5 burns, the combustion gas emits CO gas which is disposed in the water heater main body 3.
It comes into contact with the detection element 1a of the detector 1, whereby the concentration of carbon monoxide in the exhaust gas is monitored.

As is clear from the description given with reference to the flow chart of FIG. 8, the CPU constituting the water heater control circuit 12 controls the CO detector drive circuit 11 by the process of step S1 to perform gas combustion. Each time the device goes into a combustion state, the sensing element 1a is heated to a first temperature higher than the sensing temperature for a certain period of time, and after heating for the certain period of time,
It functions as drive control means 12b that keeps the detection element heated to the detection temperature while the gas combustion apparatus is in the combustion state. Also,
By the processing of steps S4 and S5, the CPU outputs 0 for issuing an alarm to the detection output of the CO detector 1 when the detection element 1a is heated to the detection temperature and the gas combustion device is not in the combustion state. It also functions as setting means 12c for storing the point reference value in the memory 12a and setting the 0 point reference value. Further, the CPU monitors the detection output of the CO detector 1 when the gas combustion apparatus is in the combustion state based on the 0-point reference value stored in the memory 12a by the processing of step S20, and this detection output is the CO gas. It functions as a determination unit 12d which determines that the predetermined concentration has exceeded a predetermined value and issues an alarm.

C constituting the water heater control circuit 12
Through the process of step S17, the PU detects that the difference between the detection output of the CO detector 1 and the 0-point reference value becomes equal to or greater than a predetermined value each time the gas combustion device changes from the combustion state to the non-combustion state. The CPU, which functions as the point drift detection means 12e and functions as the drive control means, controls the CO detector drive circuit 11 according to the detection by the 0-point drift detection means,
To a second temperature that is higher than the temperature of the above and is sufficiently high to remove deposits that decompose at high temperatures such as oil smoke and sulfides.
To heat up for a predetermined time.

In the embodiment of FIG. 8, the CO detector drive circuit 11 causes the detector element 1a of the CO detector 1 to 120 m.
As a condition for heating the sensing element 1a to 550 ° C. by passing the heating current of A for 3 minutes, Vs-V in step S17.
_Although it is determined that ₀ > 0.5V, the condition that satisfies such a condition does not depend on the adherence of oil smoke or sulfide to the detection element 1a, and the adjustment variable resistor in the CO detector 1 Also occurs when the 0-point reference value shifts due to long-term vibration or shock. If this occurs, the zero point reference value is not corrected even if high temperature heat-up is performed in step S18 to eliminate the decrease in sensitivity, and therefore step S18 is performed each time the water heater is ignited and extinguished. High-temperature heat-up is performed, and the effect of reducing the number of high-temperature heat-ups may be diminished.

FIG. 10 is a flowchart showing a partial modification of the embodiment shown in FIG. 8, and steps S17 and S18.
Between step S21 and step S21, a step S21 for determining whether the flag F is 1 is inserted, and a step S22 for setting the flag F to 1 is inserted after step S18. As a result, when the determination in step S21 is NO, the process proceeds to step S18, and the determination in step S21 is Y.
At the time of ES, even though the high temperature heat-up is once performed in step S18,
It is determined that the cause of the determination of 17 still being YES is not the sensitivity decrease but the deviation of the 0-point reference value, and the process returns to step S1 to replace the 0-point reference value with a new one. . Then, the determination in step S17 is
When it becomes O, the flag F is set to 0 in step S23 and then the process returns to step S7.
By changing this part, the high temperature heat-up in step S18 when the 0-point reference value is shifted due to long-term vibration or shock in the adjustment variable resistor or the like in the CO detector 1 is ended in the minimum number of times. Will be able to.

As is clear from the description given with reference to the flow chart of FIG. 10, the CPU functioning as the setting means 12c constituting the water heater control circuit 12 executes the step S21.
By the processing of S23 to S23, when the zero-point drift detection means 12e detects the temperature immediately after the detection element 1a is heated to the second temperature, the detection element 1a is thereafter heated to the detection temperature and the gas combustion device is CO when not in combustion state
Memory 1 with the detection output of detector 1 as a new reference value of 0 point
2a.

FIG. 11 is a flowchart of the second embodiment, in which high-temperature heat-up is not performed under the condition that Vs-V ₀ > 0.5, but the number of times of ignition-extinguishing of the water heater is predetermined. This is to be performed when the value exceeds the value. In the flowchart of the figure, step S25 for setting the count value of the A counter formed in a predetermined area of the memory 12a to 0 is inserted between step S5 and step S6 in the flowchart of FIG. Also, FIG.
Step S26 of incrementing the A counter in place of step S14 in the flowchart of FIG. 8 and determining whether or not the count value of the A counter is 5000 instead of steps S16 and S17 in the flowchart of FIG. S27 is executed. Then, when the count value of the A counter reaches 5000, the fourth control signal is first output to the CO detector drive circuit 11 in step S18, and the CO detector drive circuit 11 causes the detection element 1a of the CO detector 1 to be detected. A heating current of 120 mA is applied for 3 minutes to heat the sensing element 1a to 550 ° C.
As a result, the sensitivity is reduced, and the deposits that change the zero-point reference value V ₀ are removed. Also,
When the determination in step S27 is NO, that is, when the count value of the A counter is less than 5000, it is determined that it is not necessary to remove the adhering matter that reduces the sensitivity and changes the 0-point reference value V ₀ , and the above steps are performed. Return to S7.

As is clear from the description given with reference to the flowchart of FIG. 11, the CPU constituting the water heater control circuit 12 causes the gas combustion apparatus to change from the combustion state to the non-combustion state by the processing of steps S25 to S17. The water heater control circuit 12 functions as a counting unit 12f that counts each time
The CPU functioning as the setting unit 12c that controls the CO detector driving circuit 11 controls the CO detector driving circuit 11 according to the count of the predetermined value or more by the counting unit 12f by the process of step S18, and the temperature is higher than the first temperature, and the oil smoke or sulfur The sensing element is heated up for a predetermined time to a second temperature that is high enough to remove deposits such as things that decompose at high temperatures.

In the above-described embodiment, the new 0-point reference value V ₀ is set when the water heater body 3 is powered on, but it may be set at any other time. C, when the sensing element is heated to the sensing temperature and the burner is not in the burning state.
The detection output of the O detector may be stored.

[0051]

As described above, according to the present invention, 0
The detection output of the CO detector when the gas combustion device is in the combustion state is monitored based on the point reference value, and this detection output is C
An alarm can be generated by determining that a predetermined value of O gas has reached a predetermined value or more, and a detection output of a CO detector is output each time the gas combustion device changes from a combustion state to a non-combustion state. When it is detected that the difference from the 0-point reference value is greater than or equal to a predetermined value, the temperature is accordingly higher than the first temperature, and is sufficiently high to remove deposits such as oil smoke and sulfide that decompose at high temperatures. Since the sensing element is heated up to the temperature of the predetermined time for a predetermined time, even if the sensing element is heated to the first temperature higher than the sensing temperature for a predetermined time, if the zero point drift of the predetermined value or more occurs, By heating up at a second temperature higher than the temperature, deposits that decompose at high temperature such as oil smoke and sulfide that cause 0-point drift will be removed, and recovery of sensitivity and elimination of 0-point drift Done and sensitivity It is possible to remove an adsorbed substance that decomposes at a high temperature that causes fluctuations in the lower or zero-point reference value, while adversely affecting the life of the sensing element or causing instability due to a transient response as much as possible. A CO gas detection device for a gas combustion device, which is highly safe and highly reliable and can monitor the CO gas concentration with high accuracy, can be obtained.

Further, by heating the sensing element to the second temperature,
Even if deposits that decompose at high temperature, such as oil smoke and sulfides that cause point drift, are removed, if there is still a zero point drift, the sensing element is still heated to the sensing temperature and the gas combustion device burns. Since the detection output of the CO detector when it is not in the state is stored as a new zero point reference value, the cause of zero point drift other than deposits can be eliminated, and gas combustion with even higher safety and reliability can be eliminated. An apparatus CO gas detector is obtained.

Further, it is assumed that when the number of times the gas combustion device is in the combustion state exceeds a predetermined value, deposits that decompose at high temperature such as oil smoke and sulfides are attached to cause zero-point drift. By heating up the second temperature higher than the first temperature, the deposits that decompose at high temperature, such as oil smoke and sulfide, which cause zero-point drift, are removed.
Since the sensitivity is recovered and the zero-point drift is eliminated, the adsorbed substance that decomposes at high temperature, which causes the sensitivity to decrease and the zero-point reference value to change, adversely affects the life of the sensing element and is unstable due to transient response. It is possible to obtain a CO gas detection device for a gas combustion device, which is highly safe and highly reliable, in which CO gas concentration can be monitored with high precision by suppressing the generation of the gas as much as possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a CO gas detection device for a gas combustion device according to the present invention.

FIG. 2 is a schematic configuration diagram of a water heater having a CO detection device for a gas combustion device according to the present invention.

FIG. 3 is a block diagram showing a configuration of a CO detection device for a gas combustion device according to the present invention, which is provided in the water heater.

FIG. 4 is a graph showing a SO ₂ test example of a CO detector.

FIG. 5 is a graph showing a relationship between a zero-point drift width and a sensitivity change rate of a CO detector tested for SO ₂ ;

FIG. 6 is a graph showing the effect of the present invention on a SO ₂ tested CO detector in comparison with a conventional heat-up case.

FIG. 7 is a waveform diagram showing a heat-up waveform of the CO detector that is normally performed each time combustion in the gas combustion apparatus is started.

8 is a flowchart showing an embodiment of a process performed by a CPU that constitutes the water heater control circuit in FIG.

9 is a flowchart showing details of a part of the flowchart of FIG.

FIG. 10 is a diagram showing a modification of part of the flowchart in FIG.

FIG. 11 is a flowchart showing another embodiment of the processing performed by the CPU constituting the water heater control circuit in FIG.

FIG. 12 is a schematic configuration diagram of a general CO detector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 CO detector 1a Detection element 11 CO detector drive means (CO detector drive circuit) 12a Storage means (memory) 12b Drive control means (CPU) 12c Setting means (CPU) 12d Judgment means (CPU) 12e 0 point drift detection Means (CPU) 12f Counting means (CPU)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Oishi 23 Minamikashima, Futamachi-cho, Tenryu-shi, Shizuoka Prefecture Yazaki Keiki Co., Ltd. (72) Inventor Akashi Kegasa, 4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka, Osaka Gas Co., Ltd. (72) Inventor Koji Moriya 4-1-2, Hirano-cho, Chuo-ku, Osaka, Osaka Incorporated (72) Inventor Yoshikatsu Ishikawa 6-35 Iwata-cho, Higashi-Osaka City, Osaka Prefecture Harman Co., Ltd.

Claims (3)

[Claims] 1. A CO detector having a catalytic combustion type detection element, which is heated to a detection temperature when the gas combustion apparatus is in a combustion state and detects CO gas contained in exhaust gas discharged from the gas combustion apparatus. CO detector driving means for driving the CO detector, and the CO detector driving means for controlling the CO detector so that the sensing element is higher than the sensing temperature each time the gas combustion apparatus enters a combustion state. After heating to a temperature for a certain period of time, after the heating for a certain period of time, drive control means for continuing to heat the detection element to the detection temperature while the gas combustion apparatus is in a combustion state, and 0 for generating an alarm.
Storage means for storing a point reference value; and a detection output of the CO detector when the detection element is heated to the detection temperature and the gas combustion device is not in a combustion state, as the 0 point reference value. Setting means for storing the 0-point reference value stored in the storage means, and monitoring the detection output of the CO detector when the gas combustion apparatus is in a combustion state with reference to the 0-point reference value stored in the storage means In the CO gas detection device for a gas combustion device, the detection output is equal to or more than a predetermined value with respect to a predetermined concentration of CO gas. A zero point drift detecting means for detecting that the difference between the detection output of the CO detector and the zero point reference value becomes a predetermined value or more each time the state is brought into a state, and the drive control means has the zero point drift value. The CO detector driving means is controlled in accordance with the detection by the shift detecting means to a second temperature higher than the first temperature and high enough to remove deposits such as oil smoke and sulfide that decompose at high temperature. A CO gas detection device for a gas combustion device, characterized in that the detection element is heated for a predetermined time. 2. The setting means, when the zero-point drift detection means detects immediately after the detection element is heated to the second temperature, then the detection element is brought into a state of being heated to the detection temperature. 2. The CO gas detection for a gas combustion device according to claim 1, wherein the detection output of the CO detector when the gas combustion device is present and is not in a combustion state is stored in the storage means as a new zero point reference value. apparatus. 3. A CO detector having a catalytic combustion type detection element, which is heated to a detection temperature when the gas combustion apparatus is in a combustion state, and detects CO gas contained in the exhaust gas discharged from the gas combustion apparatus. CO detector driving means for driving the CO detector, and the CO detector driving means for controlling the CO detector so that the sensing element is higher than the sensing temperature each time the gas combustion apparatus enters a combustion state. After heating to a temperature for a certain period of time, after the heating for a certain period of time, drive control means for continuing to heat the detection element to the detection temperature while the gas combustion apparatus is in a combustion state, and 0 for generating an alarm.
Storage means for storing a point reference value; and a detection output of the CO detector when the detection element is heated to the detection temperature and the gas combustion device is not in a combustion state, as the 0 point reference value. Setting means for storing the 0-point reference value stored in the storage means, and monitoring the detection output of the CO detector when the gas combustion apparatus is in a combustion state with reference to the 0-point reference value stored in the storage means In the CO gas detection device for a gas combustion device, the detection output is equal to or more than a predetermined value with respect to a predetermined concentration of CO gas. The driving control means controls the CO detector driving means in accordance with the counting of a predetermined value or more by the counting means, and the counting means counts each time Ku, oil smoke and sulfides said sensing element a predetermined time heat-up CO gas detecting device for a gas combustion apparatus, characterized in that to a sufficiently high second temperature to remove deposits decompose at high temperatures, such as.