JPH07324739A - Combustor - Google Patents

Abstract

PURPOSE:To provide a combustor capable of successive use thereof even if an abnormal combustion is produced, while avoiding the abnormal combustion to the utmost. CONSTITUTION:A combustor is constructed such that the number of combustion burners is increased as the target supply amount of a fuel is increased, and such that in change-over of the number of combustion burners the number of combustion burners is set to be larger than the lowest target supply amount of a fuel serving to keep the present stage to alter the supply amount of a fuel to the instructed target supply amount of a fuel, and further such that a fan 4 is controlled such that the amount of air to combustion burners 2a, 2b becomes the target amount of air set corresponding to the supply amount of a fuel. Once abnormal combustion is detected by a CO sensor S, the predetermined number of combustion burners is selected, and the change-over of the number of burners is interrupted and the maximum of the supply amount of a fuel supplied in the number of combustion burners is more reduced than the maximum target supply amount of a fuel in the number of combustion burners.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply state adjusting means for switching the number of combustion burners to be in a fuel supply state among a plurality of burners to a plurality of stages and adjusting the fuel supply amount to the combustion burners. And ventilation means for ventilating combustion air to the plurality of combustion burners, and control means for controlling each of the ventilation means and the fuel supply state adjusting means, and the control means is instructed. The larger the target fuel supply amount, the larger the number of combustion burners, and
In switching the number of combustion burners, the maximum target fuel supply amount for maintaining that stage is set to be larger than the minimum target fuel supply amount for maintaining that stage in the next stage on the combustion burner number increasing side from that stage, The fuel supply state adjusting means is controlled so as to switch the number of combustion burners and to set the fuel supply amount to a commanded target fuel supply amount, and further, the ventilation amount to the combustion burner is changed. The present invention relates to a combustion device configured to control the ventilation means so that a target ventilation amount set corresponding to a fuel supply amount supplied to the.

[0002]

2. Description of the Related Art In the above combustion apparatus, the combustion amount of the burner is maintained as stable as possible by switching so that the number of combustion burners increases as the commanded target fuel supply amount increases. The adjustment range of (fuel supply amount) can be set wide, and the so-called hunting phenomenon, in which the number of combustion burners is frequently changed only by slightly changing the target fuel supply amount, is suppressed. It is a thing.

That is, for example, when the target fuel supply amount is small, the fuel supply per unit area in the burner is reduced by reducing the number of combustion burners as compared with the case where all of the plurality of burners are in the fuel supply state. The amount of fuel (fuel density) can be secured at a value higher than the set amount, and the combustion state of the burner is stabilized. It is possible to maintain stable combustion within the range and achieve stable combustion.

Further, in switching the number of combustion burners, the maximum target fuel supply amount for maintaining the stage is set to be lower than the minimum target fuel supply amount for maintaining the stage in the next stage on the combustion burner number increasing side. By setting a large value,
The hunting phenomenon can be suppressed as much as possible by providing a lap margin between the target fuel supply amount for switching the combustion burner number to the increasing side and the target fuel supply amount for switching to the decreasing side. .

By the way, in the combustion device having the above structure,
Conventionally, for example, incomplete combustion or abnormal combustion that may result in incomplete combustion due to the fact that the ventilation path of the ventilation means is blocked by dust or the like and the ventilation volume for the burner decreases from the target ventilation volume, etc. When a state occurs, the ventilation volume of the ventilation means (for example, when a fan is used as the ventilation means, the target rotation speed of the fan, etc.) is made larger than the target ventilation volume to avoid incomplete combustion. There was a thing (for example, refer to Japanese Patent Laid-Open No. 5-215329).

However, in the above-mentioned structure, there is a disadvantage that noise increases as the amount of ventilation increases. Further, when the burner is being burned while the target ventilation amount set corresponding to the target fuel supply amount is set to a ventilation amount close to the maximum amount of the ventilation capacity of the ventilation means, When an abnormal combustion state in which there is a possibility of complete combustion or incomplete combustion occurs, there is a disadvantage such that it becomes impossible to increase the target ventilation amount.

Therefore, as a method of eliminating the above disadvantages, it has been considered to reduce the maximum target fuel supply amount when an incomplete combustion or an abnormal combustion state which may cause incomplete combustion occurs.

[0008]

However, the ventilation amount for one burner of the plurality of burners is almost the same whether the burner burns only the burner or all the burners burn. Because it needs ventilation,
For example, as shown in FIG. 4, even when the number of combustion burners is switched, the target ventilation amount of the ventilation unit with respect to the maximum target fuel supply amount in each stage is almost the same value. However, when the configuration for reducing the maximum target fuel supply amount is adopted, the switching target fuel supply amount for increasing the number of combustion burners and the switching target fuel supply amount for decreasing the combustion burner number as described above are used. The amount of lap between the combustion burners decreases or disappears, and the target fuel supply amount is changed frequently in the vicinity of the target fuel supply amount for switching the combustion burner number. Switching will be performed, the burner will be ignited and extinguished frequently, and on the contrary, the amount of unburned gas generated will increase and the incomplete combustion or abnormal combustion state that may cause incomplete combustion will worsen. There is a disadvantage that

The present invention provides a combustion apparatus having the above structure,
It is an object of the present invention to provide a combustion device that can continue to use the combustion device while avoiding the abnormal combustion state as much as possible with a rational configuration even when the abnormal combustion state occurs.

[0010]

The features of the first invention are as follows:
Of the plurality of burners, the number of combustion burners that are brought into a fuel supply state is switched to a plurality of stages, and fuel supply state adjusting means for adjusting the amount of fuel supply to the combustion burner, and combustion for the plurality of combustion burners Ventilation means to ventilate the air,
A control unit for controlling each of the ventilation unit and the fuel supply state adjusting unit is provided, and the control unit increases the number of the combustion burners as the commanded target fuel supply amount increases, and When switching the number of burners,
The maximum target fuel supply amount to maintain that stage is set to be larger than the minimum target fuel supply amount to maintain that stage in the next stage on the side where the number of combustion burners increases from that stage, and the number of combustion burners is switched. , And controlling the fuel supply state adjusting means so that the fuel supply amount becomes a commanded target fuel supply amount, and further, the ventilation amount to the combustion burner,
In a combustion device configured to control the ventilation means such that the target ventilation amount set corresponding to the fuel supply amount supplied to the combustion burner, incomplete combustion or incomplete combustion of the burner is performed. An abnormal combustion state detection means for detecting an abnormal combustion state that may cause combustion is provided, and the control means selects a predetermined number of combustion burners when the abnormal combustion state detection means detects the abnormal combustion. Then, the switching of the number of burners is stopped, and the maximum amount of fuel supply supplied at the number of combustion burners is made smaller than the maximum target fuel supply amount at the number of combustion burners. It is in.

A characteristic configuration of the second invention is to specify a configuration suitable for carrying out the first invention, wherein the control means is
When the abnormal combustion is detected by the abnormal combustion state detection means, in a state where fuel is supplied to all the burners,
The point is that the switching of the number of combustion burners is stopped.

A characteristic configuration of the third invention is to specify a configuration suitable for carrying out the first or second invention, wherein the abnormal combustion state detection means is characterized by the unburned gas concentration in the combustion gas of the burner. It is configured to detect the abnormal combustion state based on the above.

A characteristic configuration of the fourth invention is to specify a configuration suitable for carrying out the first, second or third invention, wherein the abnormal combustion state detecting means is ventilated by the ventilation means. The abnormal combustion state is detected based on the decrease in the amount.

The characteristic configuration of the fifth invention is that the first, second, and third
Alternatively, the present invention specifies a configuration suitable for carrying out the fourth aspect of the present invention, and is provided with an alarm means for performing an alarm when the abnormal combustion state detecting means detects the abnormal combustion state.

[0015]

According to the characterizing feature of the first invention, when the incomplete combustion of the burner or the abnormal combustion state which may cause the incomplete combustion is detected, the number of combustion burners is determined by the predetermined number of combustion burners selected. The switching is stopped, and moreover, the maximum amount of fuel supply supplied in the number of combustion burners is smaller than the preset maximum target fuel supply amount in the number of combustion burners.

As a result, even if the ventilation volume is reduced from the target ventilation volume due to the reason that the ventilation channel is blocked by dust or the like,
As the maximum amount of fuel supply decreases, the maximum air flow required for combustion also decreases, so the fuel supply and air flow are maintained in an almost appropriate state, and abnormal combustion conditions are avoided as much as possible. The proper combustion state can be achieved. Moreover, when the abnormal combustion state is detected, the switching of the number of combustion burners is stopped, so even if the maximum value of the fuel supply amount is reduced, the frequent switching of the number of combustion burners causes the ignition of the burner, Generation of unburned gas accompanying digestion is also suppressed, and a proper combustion state can be maintained as much as possible.

According to the characterizing structure of the second invention, the following function is obtained in addition to the function of the characterizing structure of the first invention. When an abnormal combustion state is detected, switching of the number of combustion burners is stopped in a state where fuel is supplied to all burners, so 1
As compared with the case where fuel is supplied only to some burners, the commandable fuel supply amount can be increased and the burner combustion amount can be maximized.

According to the characteristic constitution of the third invention, in addition to the operation of the characteristic constitution of the first or second invention, there is the following operation.
Since the abnormal combustion state is detected based on the unburned gas concentration in the burner combustion gas, the unburned gas concentration that may be dangerous to the human body is increased due to, for example, blockage of the ventilation passage. Can be prevented in advance.

According to the characteristic constitution of the fourth invention, the first and second
Alternatively, the following operation is provided in addition to the operation according to the characteristic configuration of the third invention. Since the abnormal combustion state is detected based on the decrease in the ventilation amount, it is possible to detect the abnormal combustion state with a simple structure and with high accuracy, as compared with the detection of the unburned gas concentration.

According to the characterizing feature of the fifth invention, there is the following effect in addition to the effect of the characterizing feature of the first, second, third or fourth invention. When the abnormal combustion state is detected, the alarm means activates the alarm, so that the user of the combustion device can surely recognize the fact.

[0021]

According to the characterizing feature of the first aspect of the present invention, even when an abnormal combustion state is detected, the amount of ventilation of the ventilation means is increased to increase noise and the number of combustion burners is changed. In a state where there is no disadvantage such as generation of unburned gas,
Abnormal combustion state will be avoided, burner as much as possible,
It became possible to continue using the equipment while maintaining proper combustion conditions.

According to the characterizing feature of the second invention, the following effect is obtained in addition to the effect of the characterizing feature of the first invention. The device can be continuously used in a state where the fuel supply amount of the burner, that is, the generated heat amount can be maximized.

According to the characterizing structure of the third invention, the following effect is obtained in addition to the effect of the characterizing structure of the first or second invention.
The unburned gas concentration becomes high, and for example, it is possible to prevent the interior of the room from being polluted by the unburned gas, and the safety in use is improved.

According to the characteristic constitution of the fourth invention, the first and second
Alternatively, there are the following effects in addition to the effects of the characteristic configuration of the third invention. The abnormal combustion state can be accurately detected with a relatively simple configuration.

According to the characterizing feature of the fifth invention, the following effect is obtained in addition to the effect of the characterizing feature of the first, second, third or fourth invention. Since the user of the apparatus can immediately recognize that the abnormal combustion state has been detected, for example, post-processing such as ventilation and maintenance processing can be executed with a small time delay.

[0026]

Embodiments will be described below with reference to the drawings. Figure 1
FIG. 1 shows a hot water supply device as an example of the combustion device according to the present invention. This hot water supply device includes a water heater A, a control unit H as a control unit for controlling the operation of the water heater A, and an operation as an operation command unit. And part R. The water heater A is connected to the combustion chamber 1, a burner unit 2 provided inside the combustion chamber 1, a heat exchanger 3 for heating water heated by the burner unit 2, and an upper portion of the combustion chamber 1. An exhaust passage 5 for discharging the combustion gas in the burner unit 2 to the outside of the room, and ventilation for supplying combustion air to the burner unit 2 and ventilating the combustion gas in the burner unit 2 to the outside through the exhaust passage 5. A fan 4 as a unit, a water supply path 6 for supplying water for heating to the heat exchanger 3, and a hot water supply path 7 for supplying hot water heated in the heat exchanger 3 to a hot water tap (not shown).
And a fuel supply path 8 for supplying fuel (gas) to the burner unit 2. Burner unit 2
An ignition igniter 9 and a frame rod 10 for detecting whether or not the burner unit 2 is ignited are provided in the vicinity of.

In the water supply passage 6, the amount of water supplied to the heat exchanger 3 Qi
The water supply amount sensor 11 for detecting the water temperature and the water temperature sensor 12 for detecting the water temperature are provided, and the hot water supply passage 7 is provided with the hot water temperature sensor 13 for detecting the hot water temperature for the hot water tap.

The burner unit 2 includes two burners 2
a, 2b, the number of combustion burners in the fuel supply state of the two burners 2a, 2b can be switched between two stages. That is, each burner 2 is connected to the fuel supply passage 8 connected to the gas supply pipe for general households.
Branch supply paths 8a and 8b are provided so that fuel can be separately supplied to a and 2b.
The on-off valves 14 and 15 for intermittently supplying the fuel, respectively.
And electromagnetic proportional valves 16 and 17 for adjusting the fuel supply amount. A main gas valve 18 is provided in the fuel supply passage 8. Therefore, by closing one of the on-off valves 14 and 15, one of the two burners 2a and 2b
Fuel is supplied to the individual valves, and both on-off valves 14 and 1
By opening 5 together, fuel is supplied to the two burners 2a and 2b. Further, in any state, the fuel supply amount can be adjusted by adjusting the solenoid proportional valves 16 and 17.

The operation unit R is connected to the control unit H by wire or wirelessly, and has an operation switch 19 for instructing start and stop of the operation of the hot water supply device, a temperature setting switch 20 for setting a set target hot water supply temperature, and a hot water supply temperature. Temperature display part 2 to display
1, operation indicator lamp 2 that indicates whether or not the vehicle is in an operating state
2. An abnormality display lamp 23 is provided as an alarm means for displaying whether or not an incomplete combustion state has occurred.

In the exhaust passage 5, a CO sensor S for detecting the concentration of carbon monoxide (hereinafter referred to as CO concentration) as an example of an unburned component contained in the combustion gas of the burner 2 is an abnormal combustion state detecting means. It is provided as an example. Figure 2
Shows the configuration of this CO sensor S. CO
The sensor S is the pedestal 2 inside the protective frame 24 made of stainless steel.
5, the sensor element 26 and the temperature compensating reference element 27
Are equipped with. The sensor element 26 and the temperature compensating reference element 27 are each composed of a platinum wire tanned with a catalyst, and are heated to about 200 ° C. by the flow of an electric current, and the unburned gas in the combustion gas contacting the surface thereof is heated. The components burn catalytically. At this time, since the catalyst tangled in the sensor element 26 has selectivity for carbon monoxide (CO), a difference occurs in the element temperatures. Since the resistance value of the platinum wire changes with temperature, when the CO concentration in the combustion gas becomes large, the difference in resistance value between the sensor element 26 and the temperature compensating reference element 27 becomes large. Therefore, the CO concentration in the combustion gas can be detected as a difference in resistance value (sensor output V). Reference numeral 28 in the drawing is a connector portion with a lead wire connected to the control portion H. FIG. 3 shows C with respect to CO concentration in the combustion gas.
The output V of the O sensor S is shown.

The control unit H includes the sensors 11, 1
2 and 13 and the detection information of the frame rod 10 are input, and based on the detection information of each of these sensors, the igniter 9, each of the on-off valves 14 and 15, each of the solenoid proportional valves 1 are input.
6, 17, the fan 4, etc. are controlled to control the combustion state of the burner unit 2. That is, when the hot water tap is opened and the water supply amount detected by the water supply amount sensor 11 reaches the set water amount, the control unit H causes the igniter 9 to operate.
Ignition is started, the hot water supply operation described below is executed, and when the water supply amount becomes less than the set water amount, the fuel supply to the burner unit 2 is stopped and the hot water supply operation is stopped.

Based on information such as the water supply amount detected by the water supply amount sensor 11, the water inlet temperature detected by the water inlet temperature sensor 12, and the set target hot water supply temperature set by the temperature setting switch 20 of the operation section R, etc. in advance. The target fuel supply amount Ip of the burner unit 2 is obtained from the set characteristics, and the solenoid proportional valves 16 and 17 are feedforward-controlled so that the actual fuel supply amount becomes the target fuel supply amount Ip, and the hot water supply temperature is also increased. The electromagnetic proportional valve 11 is feedback-controlled so that the hot water supply temperature detected by the sensor 13 reaches the set target hot water supply temperature, and the fuel supply amount to the burner unit 2 is adjusted. Further, the rotation speed of the fan 4 is set to be a target rotation speed (target air flow rate) determined based on a preset characteristic as shown in FIG. 4, for example, with respect to the target fuel supply amount Ip. The rotation speed of the fan 4 is controlled to execute combustion control so that a proper burner combustion state is achieved.

The controller H is configured to switch and control the number of combustion burners so that the greater the target fuel supply amount Ip, the greater the number of combustion burners. That is,
When the target fuel supply amount Ip is small, two on-off valves 1
Either of the valves 4 and 15 is closed to supply fuel to only one burner, and the electromagnetic control valve for the burner in the fuel supply state is controlled to adjust the fuel supply amount Ip. When the target fuel supply amount becomes large, each on-off valve is opened to control the fuel supply to the two burners (all burners).
The electromagnetic proportional valves 16 and 17 are controlled to adjust the fuel supply amount Ip. Therefore, the on-off valves 14 and 15 and the electromagnetic proportional valves 16 and 17 constitute the fuel supply state adjusting means B. Further, the fan 4 is configured to constantly ventilate the combustion air to two burners (all burners) at the same time regardless of whether the number of combustion burners is one or two. . As a result, when the number of combustion burners is one, the characteristics shown by line L1 in FIG. 4 are maintained, and when the number of combustion burners is two, the characteristics shown by line L2 are maintained, and the number of combustion burners is Is 1
The maximum target rotation speed of the fan 4 in the case of the number of combustion burners and the maximum target rotation speed of the fan in the case of the number of combustion burners of 2 (the state where all burners burn) have characteristics that are approximately the same value. The target rotation speed setting in each state is executed.

Further, in order to suppress hunting in which the number of combustion burners is frequently switched only by slightly changing the target fuel supply amount, the maximum target fuel supply amount Ipm1 in the case of one combustion burner is set to When the number of burners is set to a value larger than the minimum target fuel supply amount Ipa2, the combustion burner number is switched to the increase side (switched at the maximum target fuel supply amount Ipm1) and to the decrease side. A lap margin is provided for the fuel supply amount in switching (switching with the minimum target fuel supply amount Ipa2) to suppress hunting.

When the control unit H detects an incomplete combustion of the burner unit 2 or an abnormal combustion state that may cause incomplete combustion, based on the detection information of the CO sensor S, the control unit H as described above. The switching of the number of combustion burners is stopped, and the maximum amount of the fuel supply amount Ip supplied at the number of combustion burners is reduced below the preset maximum target fuel supply amount Ipm.

The control operation of the control unit will be described below with reference to the control flowcharts shown in FIGS. When the operation switch 19 is turned on and the amount of water supplied exceeds the set value by opening the hot water tap, the igniter 9 ignites the burner unit 2 and the frame rod 10
When ignition is detected by and the start of combustion is confirmed, C
The energization of the O sensor S is started to heat it, and after waiting for about 40 seconds, the reading of the detection value CO by the CO sensor S is started (steps 1 to 4). At the same time when the CO sensor S is energized, the counting of the combustion duration integration timer is started (step 5).

It should be noted that the sensor temperature is about 4 seconds until about 20 seconds elapse after the energization of the CO sensor S is started.
Heat cleaning is performed in which dust and the like that are heated to 00 degrees and adhered to the sensor surface are incinerated and removed by high heat. After 20 seconds, the sensor temperature becomes CO
It is heated to about 200 degrees for concentration detection.

After that, the operation of closing the hot water tap was not performed, and CO
If the value CO detected by the sensor S is less than 1000 ppm, it is determined that the combustion state is normal, and the number of combustion burners is determined based on the target fuel supply amount obtained and commanded from the detection information of each sensor as described above. Switching control is executed (steps 6 to 8). Then, if the time measured by the timer Tx (combustion continuation time) is equal to or longer than the set continuation time Ta (60 minutes) while the state where the detection value CO by the CO sensor S is less than 1000 ppm is continued, the burner unit 2 The fuel supply is stopped to forcibly stop the combustion, and after the combustion of the burner unit 2 is stopped, the fan 4 is rotated for 1 minute to execute the post-purge (step 9).
~ 11). After that, if there is a reset operation such as an OFF / ON operation of the operation switch 19 or a closing / opening operation of the hot water tap,
Return to step 1 (step 12).

When the value CO detected by the CO sensor S becomes 1000 ppm or more, a predetermined weight is applied to the integrated value in the integration timer, that is, the integrated value is
The combustion continuation time is integrated by making the value CO detected by the sensor S larger than that when it is less than 1000 ppm (step 13). Then, while the accumulated time does not reach the set duration Ta, the detected value CO by the CO sensor S is 1000
When the value is above the ppm and below 2000 ppm, the set time (2
0 sec) or more, the number of combustion burners is selected to be two, the switching of the number of combustion burners is stopped, and the maximum amount of fuel supply is set by a set amount ΔI more than the target fuel supply amount Ipm2.
The value Ipb is decreased by p, and the abnormality display lamp 23 is turned on (steps 14 to 20). Therefore, after the switching of the number of combustion burners is stopped, the target fuel supply amount adjustment range is from the minimum target fuel supply amount Ipa2 in FIG. 4 to the reduced maximum amount Ipb. In this way, by reducing the required maximum ventilation amount to the burner unit 2, even if the ventilation amount is reduced due to blockage in the exhaust passage 5, the number of combustion burners is not switched, and the burner ignition is performed. The combustion state of the burner unit 2 can be set to an appropriate air-fuel ratio while preventing the generation of high-concentration carbon monoxide accompanying the digestion.
In addition, since the configuration is such that the abnormal combustion state is determined based on the CO concentration that may cause indoor pollution and may affect the human body, it is possible to prevent the CO concentration from becoming high and prevent it from being used. Will improve the safety of.

The value CO detected by the CO sensor S is maintained even after the control for reducing the maximum amount of fuel supply is executed.
Is 1000ppm or more and less than 2000ppm is 1
When it continues for 0 seconds, the combustion of the burner unit 2 is stopped, the counter is counted up, and the count value N
Is less than “3”, the process proceeds to step 11, and after the post-purge, the operation switch 19 is turned off and on,
It is reset by the closing / opening operation of the hot water tap (steps 16, 21, 22, 23, 24)). Also, CO sensor S
Detected value CO by 1000ppm or more, 2000pp
If the state of less than m continues to stop combustion 3 times or more (the count value N is 3 or more), the abnormality display lamp 23 blinks at a predetermined cycle and the post-purge is set to 1
After 4 minutes, and after the interlock control is executed for 4 hours, the operation switch 19 is reset by an OFF / ON operation, a hot water tap closing / opening operation, or the like (steps 24, 2).
7-30). While the interlock control is being executed, no switch is operated even if any switch of the operation unit R is operated, and the combustion stopped state is maintained. As a result, it is possible to prevent the hot water supply device from being accidentally continued in a state where the CO concentration is high and the human body may be adversely affected, and the user of the hot water supply device can recognize that the maintenance process is necessary.

The count value N is stored in a non-volatile memory such as an EEPROM, and as described above,
In the normal combustion state in which the detected value CO by the CO sensor S is less than 1000 ppm, the count value N is reset only when the combustion is stopped, and the detected value CO by the CO sensor S seems to remain in the state of 1000 ppm or more. In this case, the stored state is maintained even when the power is turned off. Further, when the ignition process is performed again after the combustion is stopped by the closing operation of the hot water tap, if the above-described reduction control of the maximum fuel supply amount is executed at the time of the previous combustion, The control state will be continued.

The value CO detected by the CO sensor S is 2000.
When it is detected that the concentration is higher than ppm, CO
If the concentration is 2000 ppm or more, it may be dangerous to the human body. Therefore, if such a state continues for 2 seconds or more, the maximum fuel supply amount Ipd which is smaller than the target fuel supply amount Ipm2 by the set amount ΔIp. And the abnormality display lamp 23 is turned on (step 1
5, 25, 31-33). Further, even after the control of reducing the maximum amount of the fuel supply is executed, if the detected value CO by the CO sensor S is 2000 ppm or more, the combustion is stopped immediately and the abnormality display lamp 23 blinks at a predetermined cycle. After performing the post-purge for 1 minute and executing the interlock control for 4 hours, the operation switch 19 is turned off / on.
It is reset by N operation, closing / opening operation of the hot water tap, etc. (steps 25 to 30).

When the hot water tap is closed during the control, the detected value CO by the CO sensor S immediately before the closing operation is read, and if the maximum amount of fuel supply is controlled to decrease. The abnormality display lamp 23 is continuously turned on (steps 34 to 36). If the value CO detected by the CO sensor S is less than 1000 ppm, the previous combustion duration time Tx is shorter than the set duration time Ta, and is 2 minutes or more, the count value N of the counter is reset (steps 37 to 37). 39), post-purge is performed for 1 minute (steps 40 and 41). Further, when re-ignition of the burner unit 2 is started based on the opening operation of the hot water tap, the energization of the CO sensor S is stopped and the process returns to step 2 (steps 40 and 42).

[Other Embodiments] (1) In the above embodiment, the case where the number of burners is two is illustrated, but it may be three or more, and even in this case, as shown in FIG. When switching the number of combustion burners, the maximum target fuel supply amount Ipm (n), Ip for maintaining the stage is maintained.
Each of m (n + 1) is set to be larger than the minimum target fuel supply amount Ipa (n + 1), Ipa (n + 2) for maintaining the stage in the next stage on the side where the number of combustion burners increases from the stage, and combustion is performed. It is set to switch the number of burners. (2) In the above embodiment, as the fuel supply state adjusting means B, the electromagnetic proportional valve is provided in each of the branch supply passages for the plurality of burners, but instead of such a configuration, as shown in FIG. , One electromagnetic proportional valve 16a is provided at a position before branching in the fuel supply passage 8 and each branch supply passage 8a, 8
It is also possible to provide only the on-off valves 14 and 15 in b. (3) In the above embodiment, when the abnormal combustion is detected,
Although the switching of the number of the combustion burners is stopped in the state where the fuel is supplied to all the burners, the number of the combustion burners is not limited to this, and the number of the combustion burners is supplied in the state where the fuel is supplied to only some of the burners. The switching may be stopped. With such a configuration, the state in which the fuel supply amount is small is maintained, so that the amount of unburned gas generated can be suppressed to a small amount. (4) In the above-described embodiment, the abnormal combustion state is detected based on the unburned gas concentration in the combustion gas of the burner, but instead of such a configuration, ventilation is performed by the ventilation means (fan). The abnormal combustion state may be detected based on the reduction in the amount of ventilation. For example,
Whether the decrease in the actual air flow rate to the burner is detected by an air volume sensor, a wind speed sensor, or a pressure sensor that detects the pressure difference between the upper side and the lower side of the ventilation path of the ventilation means,
Alternatively, the drive power value for the ventilation means (that is, the work amount of the ventilation means) is controlled to be maintained at the target rotation speed, and based on the drive power value in a state where the target rotation speed is maintained,
A configuration may be adopted in which the abnormal combustion state is detected by detecting a decrease in the air flow rate to the burner. (5) In the above embodiment, when the abnormal combustion state is detected, the maximum amount of the combustion supply amount is reduced by a predetermined amount from the target maximum fuel supply amount. However, instead of such a configuration If the abnormal combustion state is detected, the maximum amount of the fuel supply amount may be controlled to be decreased by a set small amount over a plurality of predetermined times. In the case of such a configuration, the maximum amount of fuel supply is decreased little by little, so that there is little change in the hot water supply temperature and the usability of the hot water supply user does not suddenly deteriorate. (6) In the above embodiment, the concentration of carbon monoxide (CO) is detected as the unburned gas in the combustion gas of the burner, but hydrogen gas (H ₂ ) and other unburned gases are used as the unburned gas. May be detected, or both the concentration of carbon monoxide (CO) and the concentration of hydrogen gas (H ₂ ) may be detected.

It should be noted that reference numerals are added to the claims to facilitate the comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a hot water supply device.

FIG. 2 is a schematic configuration diagram of a CO sensor.

FIG. 3 is an output characteristic diagram of a CO sensor

FIG. 4 is a characteristic diagram of ventilation amount with respect to fuel supply amount.

FIG. 5 is a flowchart of control operation

FIG. 6 is a flowchart of control operation

FIG. 7 is a flowchart of control operation

FIG. 8 is a characteristic diagram of the ventilation amount with respect to the fuel supply amount of another embodiment.

FIG. 9 is a schematic configuration diagram of a hot water supply device according to another embodiment.

[Explanation of symbols]

 2a, 2b burner 4 ventilation means 23 alarm means B fuel supply state adjusting means H control means Ip fuel supply amount Ipm maximum target fuel supply amount Ipa minimum target fuel supply amount S abnormal combustion state detecting means

Claims (5)

[Claims] 1. A fuel for switching the number of combustion burners to be in a fuel supply state among a plurality of burners (2a), (2b) in a plurality of stages and for adjusting a fuel supply amount (Ip) to the combustion burner. Supply state adjusting means (B), ventilation means (4) for passing combustion air to the plurality of combustion burners (2a), (2b), the ventilation means (4) and the fuel supply state adjusting means (B) is provided with a control means (H) for controlling each, and the control means (H) increases the number of the combustion burners as the commanded target fuel supply amount (Ip) increases. , When switching the number of combustion burners, the maximum target fuel supply amount (Ipm) for maintaining the stage is set to the minimum target fuel supply amount (Ip) for maintaining the stage in the next stage on the combustion burner number increasing side from the stage.
The fuel supply state adjusting means (B) is controlled so that the combustion burner number is switched to a value larger than a) and the fuel supply amount (Ip) is set to the commanded target fuel supply amount. Further, the ventilation means (4) is controlled such that the ventilation amount to the combustion burner becomes a target ventilation amount set corresponding to the fuel supply amount (Ip) supplied to the combustion burner. An abnormal combustion state detection means (S) for detecting an incomplete combustion of the combustion burner or an abnormal combustion state that may cause incomplete combustion, and the control means ( H), when the abnormal combustion state detecting means (S) detects the abnormal combustion, selects a predetermined number of combustion burners, stops the switching of the burner numbers, and supplies at the same combustion burner number. The maximum amount of fuel supply amount, the in the combustion burner speed maximum target fuel supply amount (Ipm) Configured combustion device to reduce than. 2. The control means (H) supplies fuel to all of the burners (2a), (2b) when the abnormal combustion is detected by the abnormal combustion state detection means (S). 2. The combustion device according to claim 1, wherein the switching of the number of combustion burners is stopped. 3. The abnormal combustion state detection means (S) is configured to detect the abnormal combustion state based on the concentration of unburned gas in the combustion gas of the combustion burner. Combustion device as described. 4. The abnormal combustion state detection means (S) is configured to detect the abnormal combustion state based on a decrease in the amount of ventilation that is ventilated by the ventilation means (4). The combustion apparatus according to 2 or 3. 5. The combustion apparatus according to claim 1, further comprising alarm means (23) for performing an alarm when the abnormal combustion state detecting means (S) detects the abnormal combustion state. .