JP2002130669A - Combustion controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly prevent the occurrence of a large ignition sound caused by the ignition to unburnt gas staying in the vicinity of a burner due to ventilation abnormality, or the infliction of uncomfortableness caused by gas odor, by precisely judging the ventilation abnormality caused by the clogging or the like of an exhaust pipe or the like. SOLUTION: In case that the burner 2 changes from ignited state to extinguished state though the controller does not execute extinguishing action to the burner 2, it detects the concentration of unburnt gas in the exhaust passage of a burner with a CO sensor S while exhausting remaining unburnt gas through the exhaust passage of the burner 2 by operating a ventilation means 6 continuously, and when the state where the concentration of the unburnt gas is above a set value for judgment continues for a set time for judgment or more, there is a high possibility of ventilation abnormality occurring, so it inhibits the combustion of the burner, on the other hand when concentration of the above unburnt gas falls under the above set value for judgment until the set time for judgment passes, it allows the reigniting action to the burner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition process in which, when an ignition command is issued, a ventilation means for ventilating combustion air through a burner is operated, and then an ignition process for performing an ignition operation on the burner is executed. The present invention relates to a combustion control device provided with control means for executing a fire extinguishing process for performing a fire extinguishing operation for the burner.

[0002]

2. Description of the Related Art The above-mentioned combustion control device is applied to, for example, a hot water supply device. When an ignition command (in the case of a hot water supply device, detection of the start of water supply) is made, a ventilation means is operated to burn a burner. After the air is sufficiently supplied, the burner is burned by performing an ignition process of performing an ignition operation on the burner while supplying fuel to the burner, thereby starting hot water supply in, for example, a hot water supply device. When there is a fire extinguishing command (in the case of a hot water supply device, detection of stoppage of water supply), the fuel supply to the burner is stopped, a fire extinguishing process is performed to extinguish the burner, and the combustion of the burner is stopped to supply hot water. Stop.

[0003] In the above-described combustion control device, there is a case where the burner is extinguished after the burner is ignited even though the fire is not extinguished (hereinafter referred to as "intermediate interruption"). As a matter of course, foreign matter adheres to the blades of the fan as a ventilation means, or the ventilation path of the burner is closed due to the blockage of the exhaust passage, and a large amount of unburned gas stays in the vicinity of the burner, resulting in insufficient oxygen. However, another possible cause is that, for example, the combustion air is not supplied to the burner temporarily due to so-called headwind, that is, outside air is blown into the exhaust passage. Therefore, conventionally, when a halfway fire occurs, the occurrence of the halfway fire is memorized, and then, when misfire occurs at the time of reignition operation to the burner, or when the halfway fire occurs again, Since the possibility of the ventilation abnormality is high, the concentration of the unburned gas in the exhaust passage is detected by the unburned gas concentration detecting means such as a CO sensor while the ventilation means is operated to perform the ventilation, and the unburned gas is detected. If the density of the
It was determined that the ventilation abnormality had occurred. And
In the case of abnormal ventilation, the burner combustion is forcibly stopped for a set time, or the combustion operation is disabled unless a power reset operation is performed, thereby preventing improper combustion operation in the abnormal ventilation state. Was like that.
Note that, as the unburned gas concentration means, a contact combustion type CO sensor which is heated to a set temperature for detection by energization is used, but conventionally, energization of the sensor is started along with execution of ignition processing. Then, the power supply to the sensor is stopped in accordance with the fire extinguishing process.

[0004]

However, according to the above-mentioned prior art, even if an intermediate fire occurs, re-ignition is allowed in the first intermediate fire and misfiring occurs during the re-ignition operation, or By detecting the concentration of unburned gas in the exhaust passage of the burner when the fire breaks out again,
Since the presence / absence of ventilation abnormality is determined, even if the cause of the first-time interruption of the fire is the ventilation abnormality, re-ignition will be performed. The unburned gas may generate a loud ignition sound at the time of the reignition operation.In addition, the reignition causes a state in which a large amount of unburned gas stays, and the unburned gas leaks to the outside. Therefore, there is a possibility that the user may feel uncomfortable due to the gas odor, and improvement has been desired.

An object of the present invention is to solve the above-mentioned disadvantages of the prior art. It is an object of the present invention to accurately determine the presence or absence of a ventilation abnormality when a burner burns out halfway, thereby avoiding the above-mentioned disadvantages. It is to provide a combustion control device that can be used.

[0006]

According to the first aspect of the present invention, the control means determines that the burner has changed from the ignited state to the extinguished state while the fire extinguishing process has not been executed. If detected by the ignition detection means, the concentration of unburned gas in the exhaust passage of the burner is detected by the unburned gas detection means while the ventilation means is continuously operated. When the state in which the concentration of the unburned gas is equal to or more than the set value for determination continues for the set time for determination or more, a combustion prohibition process for inhibiting combustion of the burner is executed, and the set time for determination is set. When the concentration of the unburned gas becomes less than the determination set value before the elapse, a re-ignition permitting process for permitting a re-ignition operation to the burner is executed.

In other words, when the burner changes from the ignited state to the fired state without executing the fire extinguishing operation on the burner, the ventilation means is continuously operated to remove the remaining unburned gas from the burner. While exhausting through the passage, the concentration of the unburned gas in the exhaust passage of the burner is detected, and when the state where the concentration of the unburned gas is equal to or more than the set value for determination has continued for the set time for determination, Since there is a high possibility that a ventilation abnormality due to a blockage or the like in the exhaust passage of the burner has occurred, a combustion prohibition process for prohibiting combustion of the burner is executed. When the concentration becomes less than the determination set value, the possibility of occurrence of ventilation abnormality due to blockage in the exhaust passage or the like is low, and therefore, a reignition permitting process for permitting a reignition operation to the burner is executed. That.

Therefore, when a burnout occurs in the middle of the burner, immediately based on the detection of the unburned gas concentration in the exhaust passage of the burner, it is possible to accurately determine whether there is a ventilation abnormality due to blockage in the exhaust passage of the burner or the like. When it is determined that the ventilation abnormality has occurred, the burner combustion is prohibited, while when the ventilation abnormality has not occurred, the burner is allowed to be re-ignited. Provided is a combustion control device capable of appropriately preventing generation of a loud ignition sound due to ignition of unburned gas staying in the vicinity and giving unpleasant sensation due to gas smell.

According to a second aspect of the present invention, in the first aspect, the control means forcibly stops the combustion operation of the burner for a set time for inhibiting the combustion in the combustion inhibition processing, and The means is configured to operate continuously for a set time for abnormal exhaust which is shorter than the set time for combustion inhibition. In other words, in the combustion prohibition process for prohibiting combustion of the burner, the combustion operation of the burner is forcibly stopped for the set time for prohibiting combustion, and the ventilation means is set for abnormal exhaust which is shorter than the set time for prohibiting combustion of the burner. Operate continuously for the set time.

[0010] Therefore, if an abnormality in ventilation due to blockage in the exhaust passage of the burner is determined based on detection of the concentration of unburned gas in the exhaust passage of the burner, the burner combustion operation is performed to inhibit combustion. Since it is forcibly stopped during the set time, during this time, even if the power switch or the like is turned on and off, the reset is not performed, and it is possible to prevent the inappropriate combustion from being performed in the state of the ventilation abnormality, Further, since the ventilation means is continuously operated for the set time for abnormal exhaust, the unburned gas remaining in the exhaust passage or the like of the burner due to the abnormal ventilation is exhausted to the outside as much as possible, so that the gas odor is reduced. Inconveniences such as pleasure can be suppressed, so that suitable means of the combustion control device according to claim 1 can be obtained.

According to a third aspect, in the first or second aspect, the unburned gas detecting means is a contact combustion type CO sensor which is heated to a set temperature for detection and detects the concentration of the unburned gas. The control means is configured to heat the CO sensor to the detection set temperature both during extinguishing and during ignition of the burner.
In other words, during both extinguishing and igniting the burner, the catalytic combustion type CO heated to the set temperature for detection is used.
The sensor detects the CO gas concentration as the concentration of the unburned gas.

Therefore, the contact combustion type CO sensor is heated to the set temperature for detection during both extinguishing and igniting of the burner, so that the temperature of the contact combustion type CO sensor is maintained at a high temperature. Dew condensation does not occur, it is possible to suppress the occurrence of problems such as fluctuations in output value and deterioration in sensitivity due to the dew condensation, and when the burner changes from the ignited state to the extinguished state, it quickly and without delay. The detection operation of the combustion gas concentration can be performed, and CO2 can be detected.
By detecting the gas concentration, the concentration of the unburned gas can be accurately detected, so that the preferable means of the combustion control device according to the first or second aspect is obtained.

According to a fourth aspect of the present invention, in the third aspect, the control means controls the C control for a set time at set time intervals.
A cleaning heating process for heating the O sensor to a temperature higher than the detection set temperature is executed. In other words, the contact combustion type CO sensor heated to the detection set temperature during both the fire extinguishing and the ignition of the burner is set for a set time at set time intervals.
A cleaning heat treatment for heating to a temperature higher than the detection set temperature is executed. Therefore, when foreign matter such as sulfide contained in the combustion gas of the burner adheres to the surface of the sensor and the detection accuracy of the CO sensor decreases,
By performing a cleaning heat treatment for heating the CO sensor to a temperature higher than the detection set temperature for a set time at set time intervals for a set time to remove the deposits, CO
The detection accuracy of the CO sensor can be prevented from lowering while maintaining a detectable state in which the sensor is heated to the set temperature for detection as much as possible.
Suitable means of the combustion control device described in (1) is obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a combustion control device according to the present invention is applied to a hot water supply device will be described with reference to the drawings. As shown in FIG. 1, the hot water supply apparatus is configured to include a hot water supply unit K for heating water to supply hot water, a control unit H for controlling the operation of the hot water supply unit K, a remote controller R for giving a control command to the control unit H, and the like. ing.

The hot water supply unit K includes a gas-fired burner 2, a heat exchanger 3 heated by the combustion of the burner 2, an igniter 4 for igniting the burner 2, and a frame for detecting whether or not the burner 2 is ignited. A rod 5 and the like are provided in the combustion chamber 1, and a blower fan 6 is provided as a ventilation means for passing the combustion air through the burner 2. That is, the flame rod 5 constitutes an ignition detecting means for detecting the ignition state of the burner 2. The blower fan 6 is provided with a rotation speed sensor 6a for detecting a rotation speed.

In the exhaust passage 20 of the burner 2, a CO sensor S as unburned gas detecting means for detecting the concentration of unburned gas in the exhaust passage 20 is provided in contact with the combustion gas of the burner 2. Have been. This CO sensor S is
Contact combustion type C that detects the concentration of carbon monoxide (CO) as the concentration of unburned gas after being heated to the set temperature for detection
An O sensor configured to output a detection value corresponding to the concentration D of the CO gas contained in the combustion gas.

FIG. 2 shows the configuration of the CO sensor S. CO sensor S is a stainless steel protective frame 2
The sensor element 23, the temperature compensation reference element 24, and the ambient temperature T of the CO sensor S
A temperature sensor 25 for detecting a is provided. FIG.
Reference numeral 28 denotes a connector part to a lead wire connected to the control unit H. The sensor element 23 and the temperature-compensating reference element 24 are each formed of a platinum wire carrying a catalyst. The sensor element 23, the temperature-compensating reference element 24, and the resistance elements 26 and 27 are the same as those in FIG. As shown in the figure, it is connected to the bridge circuit state.

The sensor element 23 and the temperature compensating reference element 24 are heated to about 250 ° C. as a set temperature for detection by the flow of an electric current, and the unburned gas components coming into contact with the surfaces thereof are burned by a catalytic action. . At this time, since the catalyst carried by the sensor element 23 has selectivity for CO gas, a difference occurs between the element temperatures of the sensor element 23 and the temperature compensation reference element 24. Since the resistance value of the platinum wire changes depending on the temperature, as the CO concentration in the combustion gas increases, the difference between the resistance values of the sensor element 23 and the temperature compensation reference element 24 increases. Therefore, the output value Vs according to the CO concentration in the combustion gas is generated by the connection between the sensor element 23 and the temperature compensation reference element 24 and the resistance elements 26 and 27 in the bridge circuit.
Is output as a voltage value (unit: volt) from the connection portion with.

The output value Vs of the CO sensor S has a temperature characteristic that changes in accordance with the ambient temperature Ta even if the CO concentration is the same. FIG. 4 shows a temperature characteristic of the output value Vs when the CO concentration D is predicted to be zero (hereinafter sometimes abbreviated as a zero concentration state). A solid line L1 in FIG. , The output value V in the zero concentration state when the CO sensor S is not deteriorated (at the time of shipment)
s shows the temperature characteristic of s. Further, the output value Vs of the CO sensor S increases in a state where the solid line L1 is translated in a direction in which the output value increases as the CO concentration D increases. FIG.
In this case, the range where the ambient temperature Ta is 70 to 200 ° C. substantially corresponds to a region where the burner 2 is burning,
The range below C substantially corresponds to a region where combustion of the burner 2 is stopped.

When the ambient temperature Ta is fixed at a predetermined temperature, there is a correlation between the CO concentration D and the output value Vs represented by the following equation. Where α is the CO sensor S
Is the output value Vs in the zero concentration state when the ambient temperature Ta is a predetermined temperature.

[0021]

Vs = α × D + β

FIG. 5 shows the correlation between the CO concentration D and the output value Vs. The solid line M1 in FIG. 5 shows the correlation when the CO sensor S is not deteriorated (initial).

In FIG. 4, as indicated by broken lines L2 and L3, as the CO sensor S is used, the output value Vs in the zero concentration state becomes parallel to the solid line L1 in the direction in which the output value decreases. It shows a tendency to decrease when it is moved. Therefore, C
Assuming that the deviation of the output value Vs in the zero concentration state between the use of the O sensor S and the initial stage is ΔV, the CO sensor S
The deviation ΔV tends to increase with the use of.
Further, the sensitivity α of the CO sensor S changes as the CO sensor S is used, and it is experimentally determined that there is a correlation represented by the following equation between the sensitivity α and the deviation ΔV. Have been.

[0024]

Α = α0 × (1−K1 × ΔV) (where α0
Is the initial value)

That is, as the device is used, the output value in the zero density state decreases, and the sensitivity α also decreases (the slope becomes gentle). Here, K1 is a predetermined constant. Therefore, the correlation between the CO concentration D of the CO sensor S during use and the output value Vs is expressed by the following equation.

[0026]

Vs = α × D + β = α0 × (1−K1 × ΔV) × D + β

As shown by a broken line L2 in FIG. 4, when the output value Vs in the zero concentration state decreases, CO
The correlation between the density D and the output value Vs is shown by a broken line M2 in FIG. 5, and similarly, as shown by a broken line L3 in FIG. 4, when the output value Vs in the zero density state decreases. , The CO concentration D and the output value Vs are as shown by a broken line M3 in FIG.

The heat exchanger 3 is connected to a water inlet 7 to which water for heating is supplied, and a hot water outlet 8 for discharging hot water heated by the heat exchanger 3 to a hot water tap 8a. . A water flow sensor 9 for detecting the flow of water to the heat exchanger 3
And an incoming water temperature sensor 1 for detecting the incoming water temperature to the heat exchanger 2
0 is provided, and the tapping path 8 is provided with a tapping temperature sensor 11 for detecting a tapping temperature from the heat exchanger 2. Further, the fuel supply passage 12 for the burner 2 is provided with an electromagnetic on-off valve 13 for interrupting the supply of fuel gas and an electromagnetic gas proportional valve 14 for adjusting the supply amount of fuel gas.

The remote controller R is communicably connected to the controller H. The remote controller R includes an operation switch 15 for instructing start and stop of the operation of the water heater, and a temperature setting switch 16 for setting a target hot water temperature. , A display section 17 for displaying a target hot water supply temperature, a notification lamp 18, a notification buzzer 19, and the like.

The control unit H includes command information from the remote controller R and various detections from the frame rod 5, the rotation speed sensor 6a, the water volume sensor 9, the incoming water temperature sensor 10, the outgoing water temperature sensor 11, and the CO sensor S. The information is entered, while
From the control unit H, drive signals for the blower fan 6, the on-off valve 13, the gas proportional valve 14, and the igniter 4 are output. Further, the control unit H includes a nonvolatile memory M such as an EEPROM.

Then, the control unit H operates the operation switch 1
When the hot water supply unit K is set to the operating state by turning on the water supply unit 5, the water flow to the heat exchanger 3 is started with the opening operation of the hot water tap 8a. When the start of water flow is detected and an ignition command is issued, the blower fan 6 is operated at a pre-purge rotation speed for a set time to perform pre-purge, and then the on-off valve 13 is opened and the gas proportional valve 14 is opened. Adjust the amount of gas for ignition,
The ignition operation to the burner 2 is performed by the igniter 4, and when the ignition is confirmed, the combustion of the burner 2 is started. On the other hand, when the stoppage of water flow is detected by the water amount sensor 9 and a fire extinguishing command is issued with the closing operation of the hot water tap 8a, the on-off valve 1
3 is controlled so that the combustion of the burner 2 is stopped by closing the valve. When the water flow is detected, the combustion amount of the burner 2 is adjusted so as to reach the target hot water supply temperature by the temperature setting switch 16, and the combustion air of an appropriate amount for the combustion amount is passed. Thus, the rotation speed of the blower fan 6 is controlled.

Therefore, when there is an ignition command using the control unit H, an ignition process for operating the blower fan 6 and then igniting the burner 2 is executed, and when there is a fire extinguishing command, Control means 100 for executing a fire extinguishing process for extinguishing the burner 2 is configured.

When the flame rod 5 detects that the burner 2 has changed from the ignited state to the extinguished state without executing the extinguishing process, the control means 100 controls In a state where the fan 6 is continuously operated, the concentration of the unburned gas (CO gas) in the exhaust passage 20 is detected by the CO sensor S, and the concentration of the unburned gas (CO gas) is detected. When the state that is equal to or more than the set value for determination continues for the set time for determination,
If a combustion prohibition process for prohibiting the combustion of the burner 2 is executed and the concentration of the unburned gas (CO gas) becomes less than the above-mentioned set value for discrimination before the set time for discrimination has elapsed, the burner The re-ignition permitting process for permitting the re-ignition of No. 2 is executed. It should be noted that a CO concentration value of 600 ppm is set as the determination setting value, and 15 seconds is set as the determination setting time.

Further, the control means 100 forcibly stops the combustion operation of the burner 2 for a set time for inhibiting the combustion in the combustion inhibition processing, and sets the blower fan 6 to the setting for inhibiting the combustion. It is configured to operate continuously for a set time for abnormal exhaustion shorter than the time. In addition, 4 hours are set as the set time for the combustion inhibition, and 10 minutes are set as the set time for the abnormal exhaust. As a specific configuration for executing the forcible combustion stop, information indicating that the combustion is in a forced stop state (ON of a combustion prohibition flag) is stored in the nonvolatile memory M, and the set time for the combustion prohibition is elapsed. Until this operation, even if an operation such as a power reset is performed, the storage of the ON information of the combustion prohibition flag is retained. After the set time for the combustion prohibition has elapsed, the storage of the ON information of the combustion prohibition flag is deleted. The control unit H is configured not to perform the combustion operation of the burner 2 while the ON information of the combustion prohibition flag is stored. Note that when the burn inhibition of the burner 2 is executed, the display unit 17 is notified to perform a maintenance call.

Further, as shown in FIG. 6, the control means 100 heats the CO sensor S to the set temperature for detection (about 250 ° C.) while the burner 2 is extinguished and ignited. And the CO sensor S for a set time th at set time intervals T.
Is configured to execute a cleaning heat treatment for heating the temperature to a temperature (heat cleaning temperature) higher than the detection set temperature. Note that the heat cleaning temperature is set at 350 ° C. as an initial value at the time of shipment, but when the output value Vs in the zero concentration state increases with the use of the CO sensor S, the heat cleaning temperature changes with time. When the output value Vs in the zero density state decreases with time, the temperature is changed to the high temperature side.

Specifically, in the cleaning heat treatment, the set time interval T is set to 24 hours, and the set time t is set.
h is set to 20 seconds, and before heating to the heat cleaning temperature, the power supply to the CO sensor S is turned on for a predetermined time ts.
(1 minute), and then the current ih necessary for heating to the heat cleaning temperature is supplied for the set time th. In FIG. 6, the current required to heat the CO sensor S to the set temperature for detection (about 250 ° C.) is indicated by im. And the CO sensor S
The reason why the power is always supplied to the sensor except for the power supply stop time ts is to prevent dew condensation on the sensor.

Next, the control operation by the control unit H will be described.
A description will be given based on the flowcharts of FIGS. When a power switch (not shown) is turned on, the above-described energization control (see FIG. 6) for the CO sensor S and hot water supply control are executed. In the hot water supply control, first, it is checked whether or not the combustion prohibition flag is ON (whether the ON information of the combustion prohibition flag is stored in the nonvolatile memory M) (step #).
1) If the combustion prohibition flag is not ON, the operation of the operation switch 15 turns on the hot water supply unit K, and in this state, the hot water tap 8a is opened and the water flow detected by the water flow sensor 8 is reduced. When the amount of water becomes equal to or more than the set water amount, an ignition command is issued (steps # 2 to # 3). When the combustion prohibition flag is ON (step # 1), it is checked whether or not a set time for combustion prohibition (4 hours) has elapsed. And turns off the combustion prohibition flag (erases the ON information of the combustion prohibition flag from the nonvolatile memory M) (steps # 30 to # 3).
1).

Next, when the ignition command is issued, normal pre-purge control for operating the blower fan 6 is executed for a preset pre-purge time (step # 4). The proportional valve 14 is opened, and the burner 2 is ignited by the igniter 4 (step #).
5). When the ignition state of the burner 2 is detected by the flame rod 16 by the above-described ignition operation (step # 6), the fuel supply amount and the ventilation amount of the blower fan 6 are adjusted and controlled so that the outlet water temperature becomes the target hot water supply temperature (step # 6). Step # 7). Then, as long as the ignition state of the burner 2 is detected, the hot water tap 8a is closed and the detected water flow rate of the water flow rate sensor 9 becomes equal to or less than the set water flow rate, or the operation switch 15 is turned off to extinguish the fire. Execute repeatedly until the command is issued,
When a fire extinguishing command is issued, the on-off valve 13 is closed to shut off fuel supply and stop burning the burner 2 (steps # 8 to # 8).
11).

When the ignition state of the burner 2 is not detected by the ignition operation (step # 6), the blower fan 6 has a longer time than the normal prepurge control.
After the long-term pre-purge control for operating the burner 2 is performed, the igniter 4 performs an ignition operation for the burner 2 (steps # 12 to # 13). When the ignition state of the burner 2 is detected by the re-ignition, the process proceeds to the step of the adjustment control (step # 14).
If the ignition state is not detected, an error message is displayed and the process returns to the first step (step # 15).

If the fire extinguishing state of the burner 2 is detected while the above-described adjustment control is repeatedly executed (step #).
8), check whether 1 minute has passed since the power was turned on,
If one minute has passed since the power was turned on, the lock operation (ignition inhibition) was performed for 20 seconds, and the blower fan 6 was turned on for 20 minutes.
Execute the forced purge that is activated for 2 seconds (Step # 16)
To 17). If the power is not turned off, the CO concentration is measured by the CO sensor S (Steps # 18 to # 18).
19).

As a result of the measurement of the CO concentration, the CO concentration was 6
When the state of 00 ppm or more continues for 15 seconds, an error indication of ventilation abnormality is displayed, the combustion prohibition flag is turned on (ON information of the combustion prohibition flag is stored in the non-volatile memory M), and 10 minutes is displayed. A forced purge is performed (steps # 20 to # 23). On the other hand, when the CO concentration is 600
If the state of ppm or more does not continue for 15 seconds, the process returns to the first step (step # 20).

When the fire extinguishing state of the burner 2 is detected, if one minute has not passed since the power was turned on (step # 16), the lock operation (ignition inhibition) is performed for two minutes and the blower fan 6 is turned on for 20 seconds. If the power is not turned off after executing the forced purge for activation, the CO concentration is measured by the CO sensor S (steps # 24 to # 26).
As a result of the measurement of the CO concentration, when the state where the CO concentration is 600 ppm or more continues for 15 seconds after the power is turned on for one minute (step # 27), the steps from the error display to the forcible purge for 10 minutes are performed. Execute (Steps # 21 to # 23). On the other hand, when the state where the CO concentration is 600 ppm or more does not continue for 15 seconds, the process returns to the first step (step # 27).

In step 18 and step 25, if the power is off, after the power is turned on,
After the lock operation (ignition inhibition) is performed again for 2 minutes, the flow from step 25 is executed.

[Another Embodiment] In the above embodiment, the combustion operation of the burner 2 is forcibly stopped for a set time for combustion inhibition even if a reset operation is performed by turning on / off the power in the combustion inhibition processing. As an example, as the combustion prohibition processing, in addition to this, for example, after the combustion operation is once stopped, the forced combustion stop state is released by a reset operation by turning on and off the power supply, and the burner 2 is stopped. May be configured to perform the ignition operation. The specific value of the set value for determination and the specific value of the set time for determination when executing the combustion prohibition process based on the detection information of the unburned gas detection means (CO sensor S) are shown in the above embodiment. The value is not limited to the numerical value (600 ppm and 15 seconds), but can be appropriately set to an appropriate value according to the combustion apparatus and the unburned gas detecting means.

In the above embodiment, the case where the CO sensor S is used as the unburned gas detecting means has been exemplified.
As the unburned gas detecting means, for example, an oxygen sensor for detecting oxygen or a hydrogen sensor for detecting hydrogen may be used.

In the above embodiment, the case where the combustion control device according to the present invention is applied to a hot water supply device has been described, but it may be applied to a combustion control device other than the hot water supply device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a water heater.

FIG. 2 is a sectional view of a CO sensor.

FIG. 3 is a circuit configuration diagram of a CO sensor.

FIG. 4 is a graph showing output characteristics of a CO sensor.

FIG. 5 is a graph showing output characteristics of a CO sensor.

FIG. 6 is a time chart showing the energization control characteristics of the CO sensor.

FIG. 7 is a flowchart of a control operation.

FIG. 8 is a flowchart of a control operation.

FIG. 9 is a flowchart of a control operation.

[Explanation of symbols]

 2 Burner 5 Ignition detection means 6 Ventilation means 100 Control means S Unburned gas detection means (CO sensor)

Claims (4)

[Claims] 1. When an ignition command is issued, a ventilation means for ventilating combustion air to a burner is operated, and then an ignition process for performing an ignition operation on the burner is executed. A control device for performing a fire extinguishing process for performing a fire extinguishing operation, wherein the control unit changes the burner from an ignition state to a fire extinguishing state even though the fire extinguishing process is not performed. When the ignition is detected by the ignition detection means for detecting the ignition state of the burner, the concentration of the unburned gas in the exhaust passage of the burner is reduced while the ventilation means is continuously operated. When the state where the concentration of the unburned gas is equal to or more than the set value for discrimination has been detected by the unburned gas detection means and has continued for the set time for discrimination or more, a combustion prohibition process for prohibiting combustion of the burner is executed. ,and When the concentration of the unburned gas becomes less than the set value for discrimination before the set time for discrimination elapses, a reignition permitting process for permitting a reignition operation to the burner is executed. Combustion control device. 2. The control means for forcibly stopping the combustion operation of the burner for a set time for prohibiting combustion in the combustion prohibition processing, and causing the ventilation means to perform a control based on the set time for prohibition of combustion. The combustion control device according to claim 1, wherein the combustion control device is configured to be continuously operated for a short set time for abnormal exhaust. 3. The non-burning gas detection means is a contact combustion type CO sensor which is heated to a set temperature for detection to detect the concentration of the unburned gas, and wherein the control means is configured to extinguish the fire of the burner. 3. The combustion control device according to claim 1, wherein the CO sensor is heated to the detection set temperature both during and during ignition. 4. 4. The cleaning device according to claim 1, wherein the control unit is configured to execute a cleaning heat treatment for heating the CO sensor to a temperature higher than the detection set temperature for a set time at set time intervals. Item 3. The combustion control device according to Item 3.