JPH11325461A - Combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain good CO detection sensitivity for a long period of time, by determining the timing of a heat cleaning based on a prescribed measuring time, in the case where a CO detection element for catalytic reaction to CO gas in exhaust gas is suitably raised of the temperature thereof for heat cleaning of the CO detection element. SOLUTION: A controller 14 of a water heater which is a combustor controls the operation of the water heater by a water heater control part 19 via various driving circuits 20 to 22 based on the CO concentration in exhaust gas detected by a CO sensor 16. A CO sensor control part 25 of the CO sensor 16 increases the electric power to a CO detection element 17 by means of a CO detection element driving circuit 24 based on a command signal from the water heater control part 19 for heat cleaning thereof. In this case, the water heater control part 19 is equipped with a fixed time timer 26, in the case where one combustion or more occurred within the fixed time measured by the fixed time timer, heat cleaning of the CO sensor 16 is accomplished by outputting the command signal from the water heater control part 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a combustion device,
More specifically, the CO detection element and C contained in exhaust gas
The present invention relates to a combustion device provided with a CO sensor that detects a CO concentration in combustion gas by causing a contact reaction with O gas.

[0002]

2. Description of the Related Art Conventionally, in a combustion device such as a gas water heater installed indoors, a CO (carbon monoxide) sensor is provided in an exhaust passage or the like, and the CO concentration detected by the CO sensor exceeds a certain limit. In addition, safety control such as stopping the combustion of the gas water heater is performed. Such a CO sensor has a so-called catalytic combustion type CO detection element (flammable gas detection element). When the CO gas in the exhaust gas contacts the energized CO detection element, the CO detection element emits the exhaust gas. By touching the gas, heat is generated according to the CO concentration in the exhaust gas, and a CO sensor output (voltage output) is output according to the change in the resistance value.

In such a CO sensor, if foreign matter such as oily smoke or sulfide adheres to the CO detection element, the detection sensitivity may be reduced or the durability of the CO detection element may be adversely affected. Conventionally, in order to prevent such a problem as a decrease in the sensitivity and durability of the CO sensor, conventionally, when the combustion of the burner is stopped, the amount of electricity supplied to the CO detection element is increased to thereby increase the CO detection element. The temperature is increased, and a heat cleaning operation is performed to burn off foreign substances adhering to the CO detection element (see, for example, JP-A-8-13).
No. 5962).

[0004]

However, in a conventional combustion apparatus in which a burner burns and a heat cleaning operation is performed each time the combustion is stopped, if a situation in which the combustion and the stop are repeatedly performed continues. The heat cleaning operation is frequently performed. For example, unlike water heaters for general household use, in commercial water heaters, there are many usage modes in which the burning and stopping of a burner are repeated endlessly in a short cycle due to intermittent use of hot water for a long time.
In such a case, in the conventional combustion device that performs the heat cleaning operation every time the burner combustion is stopped, the heat cleaning operation is performed many times in one day, and the number of times of heat cleaning per day becomes unnecessarily large. As a result, the life of the CO sensor is shortened.

[0005] Commercial water heaters are often used intermittently, but are often used continuously for a long time depending on the business application. For this reason, depending on the business use, it may be used continuously without stopping even once a day. In such a case, since the combustion is continued for a long time without performing any heat cleaning, a large amount of foreign matter is deposited on the CO detection element, and the detection sensitivity of the CO detection element is reduced. There is a disadvantage that the durability of the detection element is reduced.

An object of the present invention is to solve such a problem, and an object of the present invention is to perform heat cleaning at an appropriate timing to reduce the detection sensitivity of the CO detection element or to reduce the detection sensitivity of the CO detection element. An object of the present invention is to provide a combustion apparatus that can maintain good sensitivity for detecting CO over a long period of time without deterioration in durability.

[0007]

In order to achieve the above object, a combustion apparatus according to a first aspect of the present invention provides a CO detection element and a CO gas contained in exhaust gas by contacting and reacting with each other. Combustion type CO sensor that detects
A combustion device comprising: a control unit for performing heat cleaning by increasing the temperature of the CO detection element by increasing the amount of electricity supplied to the O detection element, wherein the time measurement unit measures time, and the time is measured by the time measurement unit. Based on the time
Means for generating a timing for determining whether or not to perform heat cleaning.

In the conventional combustion apparatus, heat cleaning is performed every time the burner stops burning. Therefore, excessive heat cleaning occurs when combustion stops frequently, or heat cleaning occurs when combustion continues for a long time. Cleaning was not performed enough. On the other hand, in the combustion device according to the first aspect, since the timing for determining whether or not to perform the heat cleaning is generated by the timing unit, the heat cleaning can be performed at an appropriate timing. Will be possible. Moreover, what is generated by the timing generation means is not the timing for performing the heat cleaning, but the timing for determining whether or not to perform the heat cleaning. Therefore, each time the timing is generated, the combustion history and the current time are determined. It is possible to determine whether or not to perform heat cleaning in consideration of a combustion state or the like, and unnecessary heat cleaning can be omitted. Therefore, according to the combustion device of the first aspect, the heat cleaning of the CO sensor can be performed at an appropriate frequency, and the durability and the detection sensitivity of the CO sensor can be maintained.

Further, the combustion device according to claim 2 is
A contact combustion type CO sensor that detects the CO concentration by causing a contact reaction between the CO detection element and the CO gas contained in the exhaust gas, and increasing the amount of electricity supplied to the CO detection element to reduce CO
Control means for performing heat cleaning by increasing the temperature of the detection element, wherein the control means determines whether or not at least one combustion has been performed within a predetermined time at a predetermined time interval. If the combustion has been performed, the heat cleaning operation must be started when the burner stops burning, and the heat cleaning operation should not be performed if the combustion has not been performed. It is characterized by.

That is, according to the second aspect of the present invention, it is determined whether or not to perform the heat cleaning operation at appropriate time intervals in a use state in which combustion and stop are frequently repeated. If the burner has been burned twice, heat cleaning is performed when the burner stops burning, so even if burning and stopping are performed frequently, the number of times of heat cleaning does not increase unnecessarily. In the case where the heat cleaning has been performed, the heat cleaning is performed only once every predetermined time, so that the number of times of the heat cleaning can be made appropriate. Further, when the combustion has not been performed within a predetermined time, unnecessary heat cleaning operation can be omitted.

[0011] The combustion device according to claim 3 is
The combustion apparatus according to claim 2, further comprising means for measuring a burn time of the burner after the previous heat cleaning, and when the burn time reaches a predetermined time, a heat cleaning operation is started.

That is, in the combustion device of the second aspect,
It is determined whether or not to perform the heat cleaning operation at an appropriate fixed time interval. As a result, when it is determined that the heat cleaning operation is to be performed, if the combustion is being performed at that time, the combustion of the burner is stopped. When the combustion operation is continued for a long time without stopping, the heat cleaning operation cannot be started. On the other hand, heat cleaning cannot be performed at an appropriate timing. However, according to the third aspect of the present invention, since the combustion time after the previous heat cleaning is measured and the heat cleaning operation is forcibly performed when the predetermined time is reached, foreign matter adheres to the CO detection element and the detection sensitivity is reduced. And the durability can be reliably prevented from decreasing.

Further, the combustion apparatus according to a fourth aspect of the present invention is the combustion apparatus according to the third aspect, wherein a CO concentration equal to or higher than a predetermined reference concentration among the CO concentrations detected by the CO sensor is integrated, Determining means for determining the degree of incomplete combustion based on the integrated value; when the burner combustion time after the previous heat cleaning has reached a predetermined time, if the integrated value is equal to or less than a predetermined value, When the cleaning operation is started and the integrated value exceeds a predetermined value, the start of the heat cleaning operation is delayed until the burner stops burning.

That is, if the heat cleaning operation is forcibly performed when the combustion time after the previous heat cleaning reaches a predetermined time, the heat cleaning operation is performed during the combustion, and the heat cleaning operation is performed during the heat cleaning operation. Cannot detect the CO concentration. Therefore, if the combustion time reaches a predetermined time when the combustion state is poor and incomplete combustion is progressing to some extent, by starting the heat cleaning operation,
For a while, the CO concentration cannot be detected, and the determination of incomplete combustion is delayed. In other words, if the detection of the CO concentration is continued without performing the heat cleaning, it is determined that the combustion is to be determined to be incomplete combustion soon and the safety control is to be started. Will be lost. On the other hand, according to the invention of claim 3, when the combustion time reaches a predetermined time, if the degree of incomplete combustion is extremely small, the heat cleaning operation is immediately performed. In the case of exceeding, the start of the heat cleaning operation is delayed until the burner stops the combustion, and the determination of incomplete combustion is not hindered.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a water heater as one embodiment of a combustion device according to the present invention.
Shown in In the embodiment shown in FIG.
A burner 4 is provided at a lower portion of the fuselage 3 which forms the body. Fuel gas is supplied to the burner 4 through a gas supply path 7 having an original solenoid valve 5 and a proportional control valve 6. The main solenoid valve 5 is a valve that only opens and closes the gas supply path 7, the proportional control valve 6 is set to an opening degree according to the control signal, the gas flow rate is adjusted to a desired value, and the combustion intensity of the burner 4 is adjusted. It is a valve that adjusts. Near the burner 4, a frame rod 8 for detecting whether or not the burner 4 is burning is provided. A fan 10 driven by a fan motor 9 is provided at the bottom of the body 3 to supply combustion air in an amount corresponding to the gas supply amount and burn gas at an appropriate air-fuel ratio.

A heat exchanger 11 is disposed above the burner 4, and the water passed through the water supply pipe 12 is heated by the heat exchanger 11 by the combustion heat of the burner 4, and the heated hot water is supplied to the hot water supply pipe 13.
Through the hot water supply. Reference numeral 14 denotes a controller that controls each part of the water heater 1. At an upper portion of the body 3 located above the heat exchanger 11, there is provided an exhaust collecting tube 15 for discharging exhaust gas after burning by the burner 4 and exchanging heat with the heat exchanger 11 to the outside. . CO in exhaust gas
The CO sensor 16 for measuring the concentration includes a CO detection element 17 for detecting the CO concentration in the exhaust gas, and a temperature sensor 18 for detecting the ambient temperature around the CO detection element 17.
The CO detection element 17 and the temperature sensor 18 are arranged in the exhaust collecting tube 15.

FIG. 2 is a block diagram mainly showing the configuration of the CO sensor 16 and a portion related to the CO sensor 16 among the functions of the controller 14 of the water heater 1. The controller 14 adjusts the drive current value of the water heater control unit 19 mainly composed of a microcomputer (CPU) for controlling the water heater, the original solenoid valve drive circuit 20 for controlling the opening and closing of the original solenoid valve 5, and the drive current value of the proportional control valve 6. A proportional valve drive circuit 21 for controlling the valve opening degree, a fan drive circuit 22 for controlling the number of revolutions of the fan 10, and a display panel 23 for displaying the operating state and the failure of the water heater 1 are provided.

Thus, the proportional control valve is controlled via the proportional valve control circuit 21 so that the detected temperature of the tap water temperature sensor (not shown) for detecting the tap temperature from the heat exchanger 11 becomes equal to the set temperature. 6 is controlled to adjust the gas supply amount to the burner 4. Further, the water heater control unit 19 controls the fan drive circuit 22 so that the rotation speed of the fan 10 becomes a predetermined standard rotation speed corresponding to the combustion amount of the burner 4.
, The voltage applied to the fan motor 9 is controlled.

The CO sensor 16 includes a contact combustion type CO detection element 17, a CO detection element drive circuit 24, a temperature sensor 18 for detecting the temperature around the CO detection element 17, and a CO sensor control section including a microcomputer. 25. When the microcomputer of the CO sensor control unit 25 receives the data request signal from the microcomputer of the water heater control unit 19, the microcomputer transmits the detection data of the CO concentration to the microcomputer of the water heater control unit 19. The data of the CO concentration is valid if the ambient temperature detected by the temperature sensor 18 is within a predetermined detection temperature range, and is invalid if the ambient temperature is out of the detection temperature range.

The CO concentration data received by the water heater control unit 19 is compared with a reference concentration for starting the integration of the CO concentration, and the CO concentration exceeding the reference value is integrated. The water heater control unit 19 determines the degree of incomplete combustion based on the integrated value of the CO concentration detected by the CO sensor 16, and controls the proportional valve control circuit 21 and the proportional control valve 6 so that the gas burns at an appropriate air-fuel ratio. To correct the gas supply amount, or to correct the rotation speed of the fan 10 via the fan drive circuit 22 and the fan motor 9. Further, when the integrated value of the CO concentration exceeds a predetermined upper limit and the degree of incomplete combustion exceeds a predetermined limit, a warning is displayed on a display panel 23 provided in the remote controller 14 or the like, and the original solenoid valve driving circuit 20 The main solenoid valve 5 is closed to stop the burner 4 from burning.

The water heater control unit 19 outputs a heat cleaning command signal to the CO sensor control unit 25 at a predetermined timing. When the CO sensor control unit 25 receives the heat cleaning command signal from the water heater control unit 19,
Through the CO detection element drive circuit 24, the CO detection element 17
And the temperature of the CO detection element 17 is increased.

FIG. 3 is a flowchart showing a heat cleaning control method for the water heater 1. In this embodiment, the water heater control unit 19 includes, as one of the functions of the microcomputer, a timer 26 (hereinafter, referred to as a fixed time timer) that counts up every fixed time Tc. Every time the fixed time Tc counted by the timer elapses, the elapsed fixed time Tc
It is determined whether or not the burner 4 has burned at least once during the period. If one or more combustions have occurred, the water heater control unit 19 outputs a heat cleaning command signal,
The heat cleaning of the sensor 16 is performed.

Referring to the flowchart of FIG. 3, when the fixed time timer 26 which has counted the fixed time Tc has timed out (S1), the water heater control unit 19 will be described.
Resets and starts the timer 26 for a fixed time, and starts measuring the next fixed time Tc (S2). Then, it is determined whether or not the burner 4 has performed at least one combustion during the elapsed fixed time Tc (S3). If at least one combustion has been performed, it is determined whether or not the burner 4 is currently burning (S4). Immediately if the combustion is stopped, or if the combustion is being performed, the combustion is stopped. After stopping, the heat cleaning of the CO sensor 16 is executed (S5). Also, in step S3, if there is no combustion of the burner 4 during the elapse of the given time Tc, the process returns to the beginning and waits for the timer 26 to time out.

In the water heater 1, even if the combustion and the stop are frequently performed, the heat cleaning of the CO sensor 16 is performed at a time interval shorter than the fixed time Tc set in the timer 26 for a fixed time. Therefore, the number of times of heat cleaning does not increase unnecessarily. That is, even if combustion is performed several times during the fixed time Tc, the heat cleaning is performed only once during the fixed time Tc, so that the number of times of the heat cleaning can be made appropriate. In addition, when the heat cleaning is simply performed for each predetermined time Tc, the water cleaning is performed even when the water heater 1 is not burning for the predetermined time Tc and the heat cleaning is unnecessary. According to the present invention, when the combustion has not been performed during the predetermined time Tc, unnecessary heat cleaning operation does not occur, and the life of the CO sensor 16 is prevented from being shortened by unnecessary heat cleaning. be able to.

(Second Embodiment) FIG. 4 shows a controller 1 used in a water heater according to another embodiment of the present invention.
4 is a block diagram showing a configuration of FIG. The configuration of the water heater 1 is as shown in FIG. In the block diagram of FIG. 4, the same parts as those in the block diagram of FIG. 2 are denoted by the same reference numerals as in FIG. In the first embodiment, when the timer 26 has timed out for a predetermined time, the elapsed time T has elapsed.
If at least one combustion has occurred during c, if the water heater 1 is burning, the heat cleaning of the CO sensor 16 is performed after the combustion is stopped, but in this embodiment, If at least one combustion has been performed during the elapse of the fixed time Tc, even if the water heater 1 is burning, the timer 27 (hereinafter, referred to as a timer 27) accumulating the combustion time Ts after the previous heat cleaning. , A combustion timer), the heat cleaning of the CO sensor 16 is executed. Here, combustion timer 2
Reference numeral 7 denotes another timer function of the microcomputer of the water heater controller 19, which is reset and started immediately after the heat cleaning, and the burning time (integrated value) after the previous heat cleaning was executed. Ts is measured, and the time is up when the combustion time Ts reaches a predetermined time.

FIG. 5 is a flowchart showing a heat cleaning control method by the controller 14. In the flowchart of FIG. 5, steps that are basically the same as those in the flowchart of FIG. 3 are given the same reference numerals as in FIG. Referring to the flowchart of FIG. 5, when the timer 26 in the water heater control unit 19 has timed out (S1), the timer 26 is restarted after reset (S2), and within a certain time Tc that has elapsed. It is determined whether or not combustion has occurred (S3). Elapsed time T
If there is no combustion during c, the process returns to the beginning and waits for the next time-up of the timer 26 for a fixed time. On the other hand, if combustion has occurred during the elapse of the predetermined time Tc, whether the water heater 1 is burning at that time (S
4) Alternatively, it is determined whether or not the time of the combustion timer 27 has expired (S6). If the combustion has stopped, or if the time of the combustion timer 27 has already expired, heat cleaning is immediately executed (step S6). S5). If not, the combustion is stopped (S7) or the heat cleaning is executed after the combustion timer 27 times out (S6) (S5). When the heat cleaning is executed (S5), the combustion timer 27 and the fixed time timer 26 are reset and restarted (S5).
8). Therefore, the combustion timer 27 measures the combustion time (integrated time) Ts after the heat cleaning.

Also in this embodiment, since it is determined whether or not to perform the heat cleaning every time the predetermined time Tc elapses, even if the water heater 1 repeats the combustion and the stop frequently, even if the water heater 1 repeats the burning and stopping frequently, the water heater 1 is repeatedly operated at short time intervals. Also, it is possible to prevent the heat cleaning from being repeatedly performed. Furthermore, even when the water heater 1 is burning at the time when the timer 26 has timed out for a certain period of time and the burning state continues for a long time, the heat cleaning is executed when the time of the combustion timer 27 is up. Even in the case where the combustion does not stop for a long time (for example, the combustion does not stop once a day), the heat cleaning can be reliably performed almost every time until the time of the combustion timer 27 expires.

The fixed time timer 26 is reset and started immediately after the timer 26 has timed out (S2) as well as immediately after the heat cleaning (S8). After that, the timer 26 for a fixed time at short time intervals
Can prevent heat cleaning.

FIGS. 6 to 9 are time charts for explaining the timing of heat cleaning in a specific combustion pattern according to the heat cleaning control shown in the flowchart of FIG. In this specific example, the timer 26 is set to time up in one hour,
The combustion timer 27 is set to be timed up when the combustion time Ts after the previous heat cleaning reaches a total of one hour.

FIG. 6 shows a case where combustion is started at time T11 and continuous combustion for 1 hour and 20 minutes is performed. Time T
Assuming that the combustion has started at 11, the combustion timer 27 starts accumulating the combustion time Ts at the same time as the combustion starts. Although the timer 26 counts up for a certain period of time at time T12, heat cleaning is suspended at time T12 because combustion is in progress, and the combustion timer 27 sets the time T13 (= T11 +
When the time is up to (60 minutes), heat cleaning is executed. That is, since the combustion is being performed in step S4 in FIG. 5, the process proceeds to step S6, and the determinations in step S7 and step S6 are repeated. When the combustion timer 27 times out, the process proceeds from step S6 to step S5 to execute the heat cleaning. It is done. When the heat cleaning is executed, the heat cleaning is performed at the same time (time T
In 13), both the timer 26 and the combustion timer 27 for a fixed time are reset and restarted.

1 hour and 20 minutes have passed since the combustion, and the water heater 1
When combustion stops, the combustion timer 27 stops. Thereafter, the timer 26 for a certain period of time sets the time T14 (= T13 + 6).
(0 minutes), the combustion has stopped at this point, and therefore, from step S1 to step S2 in FIG.
The process proceeds to step S5 via S3 and S4, and heat cleaning is performed at time T14.

As described above, when the combustion and the stop are repeated with the combustion time Ts longer than the time-up time of the fixed time timer 26 and the combustion timer 27, both the fixed time timer 26 and the combustion timer 27 work. Heat cleaning is performed.

FIG. 7 shows the case of continuous combustion for 50 minutes. Since the combustion is not performed from the time T21 to the time T22, the heat cleaning is not executed even if the timer 26 has timed out at the time T22 for a certain time (steps S1, S2, S3 and return in FIG. 5). Thereafter, when the combustion starts, the combustion timer 27 starts to accumulate. However, since the combustion timer 27 does not time up during the 50-minute combustion, the combustion timer 27 does not perform the heat cleaning. When the timer 26 has timed out for a fixed time at the time T23 during the combustion, the water heater 1 is burning, so the process proceeds from the step S4 in FIG. 5 to the steps S6 and S7, and waits until the combustion is stopped at the time T24 to heat. Cleaning is performed. When the heat cleaning is performed at time T24,
The fixed time timer 26 and the combustion timer 27 are reset and restarted.

As described above, when the combustion time Ts is slightly shorter than the time-up time of the timer 26 or the combustion timer 27 for a fixed time and the combustion stop period is long, heat cleaning is mainly controlled by the timer 26 for a certain time. However, even if the combustion time Ts is shorter than the time-up time of the fixed time timer 26 or the combustion timer 27, if the combustion stop period is very short, as in the case of FIG.
Heat cleaning may be controlled by the fixed time timer 26 and the combustion timer 27 in some cases.

FIG. 8 shows a case where the combustion for a short time is performed intermittently. At time @ T31 and time @ T32,
Although the combustion is performed for a short time, the combustion timer 27 does not time up during this time, and heat cleaning is performed at time T33 when the timer 26 has timed out for a predetermined time (steps S1, S2, and S2 in FIG. 5). S3, S
4, S5). Next, at time T34 at which the timer 26 has timed out for a fixed time, no heat cleaning is performed since combustion has not been performed for one hour from time T33 to T34 (steps S1, S2, S3 and return in FIG. 5). . Further, when the timer 26 counts up for a certain period of time at time T35 after one hour has elapsed, the combustion is performed during this one hour (T34 to T35).
From step S1 to step S5 via steps S2, S3 and S4, and heat cleaning is executed at time T35.

When such short-time combustion is intermittently repeated, heat cleaning is performed mainly by the operation of the timer 26 for a certain period of time.

FIG. 9 shows a case where continuous combustion is performed for a long time. After the start of combustion, the combustion is in progress at time T41 when the timer 26 first counts up for a certain period of time. Therefore, the process proceeds from step S4 to step S6 in FIG. 5, and the determinations of step S7 and step S6 are repeated. At time T42 when the time is up, the process proceeds from step S6 to step S5, and heat cleaning is performed. Then, in step S8, the fixed time timer 26 and the combustion timer 27 are both reset and restarted. Next, at the time when the timer 26 has timed out for a certain time (time T43), the combustion is in progress, but the combustion timer 27 has also been timed up at the same time. Therefore, the process proceeds from step S4 to step S5 in FIG. At time T43, heat cleaning is performed. As described above, even when continuous combustion is performed for a long time, heat cleaning can be performed at appropriate intervals set by the combustion timer 27.

(Third Embodiment) FIG. 10 is a flowchart showing a method for controlling the heat cleaning of a water heater according to still another embodiment of the present invention. The configurations of the water heater 1, the controller 14, and the like are as shown in FIGS. 1 and 2. In the flowchart of FIG. 10, steps that are basically the same as those in the flowchart of FIG. Has been granted. In the embodiment of FIG. 5, step S6
If the combustion timer 27 has expired, the heat cleaning is immediately executed. However, in the embodiment of FIG. 10, the determination in step S9 is added after step S6. That is, in the embodiment of FIG.
If the time of the combustion timer 27 has expired, it is determined whether the integrated value of the CO concentration exceeding the reference concentration is equal to or less than a predetermined value (S9). (S5) If it exceeds the predetermined value, heat cleaning is performed after combustion is stopped (S5).
9, S7, S5).

In this embodiment, by adding step S9, when the integrated value of the CO concentration exceeds a predetermined value and some incomplete combustion is progressing, the CO concentration is maintained until the combustion is stopped. Detection can continue. Therefore, it is possible to prevent the timing of the incomplete combustion determination and the safety operation from being delayed. Step S9
May be zero. That is, if the CO concentration exceeding the reference concentration is integrated even if it is slight, it may be determined that incomplete combustion is in progress.

[0040]

As described in detail above, claim 1 of the present invention
According to the combustion apparatus, it is possible to determine whether to perform heat cleaning at an appropriate timing in consideration of a combustion history, a combustion state at that time, and the like, and perform heat cleaning at an appropriate timing as necessary. Can be performed.

According to the second aspect of the present invention, it is determined at a predetermined time interval whether or not at least one combustion has been performed within the predetermined time. When the combustion is stopped, the heat cleaning operation is started, and when the combustion is not performed, the heat cleaning operation is not performed.
Even if burning and stopping are performed frequently, the number of times of heat cleaning does not increase unnecessarily, and if burning is performed, heat cleaning is performed only once every predetermined time. Can be adjusted appropriately. Further, when the combustion has not been performed within a predetermined time, unnecessary heat cleaning operation can be omitted.

According to the third aspect of the present invention, there is provided a means for measuring the burn time of the burner after the previous heat cleaning, and when the burn time reaches a predetermined time, the heat cleaning operation is started. Therefore, when the combustion time requiring heat cleaning has elapsed for a long period of continuous combustion, heat cleaning can be reliably performed, and foreign matter adheres to the CO detection element, lowering the detection sensitivity. And the durability can be reliably prevented from being lowered.

Further, according to the invention described in claim 4,
When the burner burn time since the last heat cleaning has reached the predetermined time, if the degree of incomplete combustion is very small, heat cleaning operation is performed immediately, but if the degree of incomplete combustion exceeds a certain level In this case, the start of the heat cleaning operation is delayed until the burner stops burning, and the situation in which the heat cleaning operation hinders the determination of incomplete combustion can be reduced as much as possible.

Therefore, according to the combustion apparatus of the first to fourth aspects, the heat cleaning is executed at an appropriate timing, and the detection sensitivity of the CO detection element is reduced and the durability of the CO detection element is reduced. And good CO detection sensitivity can be maintained over a long period of time.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a water heater as an example of a combustion device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing functions of main parts of a controller of the water heater.

FIG. 3 is a flowchart illustrating heat cleaning control of the water heater.

FIG. 4 is a block diagram showing functions of main parts of a controller of a water heater according to another embodiment of the present invention.

FIG. 5 is a flowchart illustrating heat cleaning control of the water heater.

FIG. 6 is an explanatory diagram showing an example of heat cleaning timing in the water heater.

FIG. 7 is an explanatory diagram showing another example of heat cleaning timing in the water heater.

FIG. 8 is an explanatory diagram showing still another example of the timing of heat cleaning in the water heater.

FIG. 9 is an explanatory diagram showing still another example of the timing of heat cleaning in the water heater.

FIG. 10 is a flowchart illustrating heat cleaning control of a water heater according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hot water supply device 4 Burner 14 Controller 16 CO sensor 17 CO detection element 19 Hot water supply control unit 24 CO detection element drive circuit 25 CO sensor control unit 26 Fixed time timer 27 Combustion timer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadahiko Oshio 93, Edocho, Chuo-ku, Kobe, Hyogo Prefecture Inside (72) Inventor Mamoru Miyazaki 93, Edocho, Chuo-ku, Kobe, Hyogo Prefecture Noritz, Inc. (72) Inventor Koji Kawakita Osaka 1-2, Hirano-cho, Chuo-ku, Osaka-shi Inside (72) Inventor Shunji Okada 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Japan

Claims (4)

[Claims] 1. A CO detection element and C contained in exhaust gas
A contact combustion type CO sensor that detects the CO concentration by contacting and reacting with O gas, and a control unit that performs heat cleaning by increasing the temperature of the CO detection element by increasing the amount of electricity supplied to the CO detection element. A combustion device, comprising: a timer for measuring time; and a unit for generating timing for determining whether to perform heat cleaning based on the time measured by the timer. Features combustion equipment. 2. A CO detection element and C contained in exhaust gas.
A contact combustion type CO sensor that detects the CO concentration by contacting and reacting with O gas, and a control unit that performs heat cleaning by increasing the temperature of the CO detection element by increasing the amount of electricity supplied to the CO detection element. In the combustion device, the control means determines whether or not at least one combustion has been performed within a predetermined time at a predetermined time interval, and if the combustion has been performed, the burner combustion is stopped. A combustion device that starts a heat cleaning operation when the state is reached, and does not execute the heat cleaning operation when combustion is not being performed. 3. The burner according to claim 2, further comprising means for measuring a burn time of the burner after the previous heat cleaning, and when the burn time reaches a predetermined time, a heat cleaning operation is started. A combustion device as described. 4. A method of integrating a CO concentration equal to or higher than a predetermined reference concentration among the CO concentrations detected by the CO sensor,
Determining means for determining the degree of incomplete combustion based on the integrated value; when the burner combustion time after the previous heat cleaning has reached a predetermined time, if the integrated value is equal to or less than a predetermined value, The combustion apparatus according to claim 3, wherein the cleaning operation is started, and when the integrated value exceeds a predetermined value, the start of the beat cleaning operation is delayed until the burner stops burning.