JP5962986B2 - Combustion device and control method of combustion device - Google Patents

Description

  The present invention relates to a combustion apparatus, and more particularly to a combustion apparatus having a carbon monoxide sensor. The present invention is suitable as a structure of a combustion apparatus that is assumed to be continuously operated for a long time, such as a combustion apparatus incorporated in a heating apparatus or the like. The present invention also relates to a method for controlling a combustion apparatus.

When a combustion device causes incomplete combustion, harmful carbon monoxide is generated. For this reason, during combustion, it is necessary to monitor the concentration of carbon monoxide in the exhaust gas and take measures such as stopping combustion if a situation occurs where carbon monoxide is generated more than expected.
As a configuration for meeting this demand, there is known a combustion apparatus provided with a carbon monoxide sensor in an exhaust path and having a function of monitoring the concentration of carbon monoxide in exhaust gas.

Here, as a typical carbon monoxide sensor, there is a catalytic combustion type carbon monoxide sensor (hereinafter abbreviated as CO sensor). The CO sensor has a catalyst element portion and a reference element portion, and compares the temperatures of both.
That is, the catalyst element portion has a catalyst and oxidizes carbon monoxide in the environment. As a result, if carbon monoxide is present in the environment, the temperature of the catalyst element portion increases.
The reference element portion does not have a function of oxidizing carbon monoxide, and the temperature does not change depending on the presence or absence of carbon monoxide.
The CO sensor compares the temperature of the catalyst element part with the temperature of the reference element part, and outputs the difference between them in the form of a voltage signal.

Incidentally, some CO sensors have hygroscopicity, and there are some CO sensors that cannot detect the exact concentration of carbon monoxide because the voltage signal fluctuates due to moisture absorption. That is, it may absorb moisture and cause malfunction.
For example, there is an element that uses an element containing silicon in the reference element portion, and silicon may absorb moisture. As a result, the heat capacity of the reference element unit increases, and the temperature of the reference element unit decreases. Therefore, the temperature difference between the accurate catalyst element portion and the reference element portion is enlarged, and a higher voltage signal is output as compared with the normal case.

  In particular, in recent years, there are various types of combustion devices called latent heat recovery types. Since the latent heat recovery type combustion devices recover the latent heat by liquefying water vapor in the combustion gas, the relative humidity of the exhaust path is high. For this reason, the CO sensor absorbs moisture and malfunctions, and a higher voltage signal is output compared to a normal case. That is, the voltage output of the CO sensor does not accurately reflect the carbon monoxide concentration in the environment, and shows a concentration higher than the actual concentration. In this way, if the CO sensor malfunctions, the carbon monoxide concentration higher than the actual concentration is shown and combustion is stopped.

In order to cope with this problem, Patent Document 1 discloses a technique for temporarily heating and heating a CO sensor to dry the CO sensor.
The combustion apparatus disclosed in Patent Document 1 heats and heats the CO sensor after the combustion operation is stopped.

Japanese Patent No. 3029551

However, the configuration of Patent Document 1 is not suitable for a combustion device (hereinafter simply referred to as a heating device) built in a heating device. Here, the heating device is characterized in that one combustion duration is longer than that of the hot water supply device.
That is, the hot water supply device is mainly used in a bath, shower, or kitchen, and has a short combustion duration time. For this reason, if the combustion device is built in the hot water supply device, if the CO sensor is heated and heated after the combustion operation is stopped, moisture adsorbed during combustion can be removed, and a normal voltage signal is always output. The
On the other hand, it is not rare that the heating device is continuously operated for 24 hours or more, and the built-in combustion device continuously burns for a long time. For this reason, the hot water supply device built in the heating device has few opportunities to stop combustion, and the CO sensor continues to absorb moisture. As a result of moisture absorption, the voltage output of the CO sensor shows a carbon monoxide concentration higher than the actual concentration. Finally, the detected concentration exceeds the threshold value, the combustion is forcibly stopped, and thereafter, the combustion becomes impossible and there is a problem that the usability is poor.

  In order to avoid this situation, it is conceivable that the CO sensor is heated and heated to dry the CO sensor while the combustion apparatus is burning. If the temperature is further increased and heated, the temperature of the catalyst excessively rises, and there is a concern about deterioration of the catalyst. Therefore, heating of the CO sensor during combustion should be avoided.

  The present invention pays attention to the above-mentioned problems of the prior art, judges the presence or absence of malfunction due to the humidity effect of the CO sensor, and in the case where combustion is impossible due to malfunction of the CO sensor, It is intended to cancel the impossible state and propose an easy-to-use combustion apparatus.

In order to solve this problem, the cause that causes the CO sensor to output a voltage signal or the like corresponding to high-concentration carbon monoxide was divided into cases. Furthermore, the case where the noncombustible state can be canceled and the case where the noncombustible state should be maintained were examined separately.
Considering the case where the CO sensor outputs a voltage signal or the like corresponding to high concentration of carbon monoxide, this may be caused by the malfunction of the sensor due to moisture absorption or when the CO sensor itself is normal. .
The cause of malfunction of the CO sensor is as described above.

  When the CO sensor is normal and the sensor outputs a voltage signal corresponding to a high concentration of carbon monoxide, the supply air itself contains carbon monoxide, A case where the carbon monoxide concentration is normal is considered.

  Therefore, when the CO sensor outputs a voltage signal corresponding to high concentration of carbon monoxide, as shown in the following table, “when the CO sensor is normal and the CO concentration in the supply air is low”, “CO "When the sensor is normal and the CO concentration in the supply air is high" "When the CO sensor is abnormal and the CO concentration in the supply air is low" "The CO sensor is abnormal and the CO concentration in the supply air is high A combination of four patterns of “case” is conceivable.

If the CO sensor detects a high concentration of carbon monoxide despite the fact that the CO sensor is normal and the CO concentration in the supply air is low, incomplete combustion has occurred and the combustion state Is expected to be due to abnormalities. For example, it is expected that the amount of generated carbon monoxide has increased due to an exhaust blockage or the like resulting in a shortage of air supply.
In this case, since a combustion abnormality has occurred, combustion should not be resumed, but a noncombustible state should be maintained.

If the CO sensor is normal and the CO concentration in the supply air is high, and the CO sensor detects a high concentration of carbon monoxide, so-called self-contamination is suspected. That is, a combustion apparatus using gas as fuel and installed in a room has a duct for supplying and exhausting air to and from the combustion section. And a combustion part and the exhaust duct are connected directly, and exhaust gas is discharged | emitted outdoors, without leaking indoors.
On the other hand, the air supply duct opens in a housing such as a heating heat source machine. Further, the intake side of the blower is opened in the casing, and the air in the casing is sucked and sent to the combustion unit. For this reason, in this type of heating heat source machine or the like, if there is a gap or the like in the enclosure that leads to the room, the room air is also sucked by the blower and used for combustion. Therefore, when a part of the exhaust path is damaged, the exhaust gas leaks into the room in which the heating heat source unit or the like is installed, and the carbon monoxide concentration in the room increases.
When such a situation occurs, carbon monoxide is concentrated in the installed room, and the carbon monoxide concentration in the room gradually increases. Finally, the CO sensor detects carbon monoxide at a concentration at which combustion should be stopped.
In addition, when a duct in which an exhaust duct and an intake duct are arranged concentrically is used, if a part of the duct is damaged, a part of the exhaust gas may be mixed in the supply air. In such a case, carbon monoxide is concentrated in the duct or the like, and finally the CO sensor detects carbon monoxide at a concentration at which combustion should be stopped.
In any case, when the CO sensor is normal and the CO concentration in the supply air is high, there is a high possibility that the supply / exhaust system is abnormal. Should do.

When the CO sensor detects a high concentration of carbon monoxide in a state where the CO sensor is abnormal and the CO concentration in the supply air is low, the CO sensor is simply malfunctioning due to the influence of humidity. Most likely not.
That is, since the CO concentration in the supply air is low, there is no abnormality in the supply / exhaust system. If it is confirmed that the CO sensor is abnormal, it is usually considered that the CO sensor malfunctioned due to the influence of humidity as the reason for detecting the high concentration of carbon monoxide. is there.
The only remaining concern is "when the CO sensor is abnormal and exhaust blockage occurs at the same time", but such a case is rare.
For this reason, when the CO sensor detects a high concentration of carbon monoxide in a state where the CO sensor is abnormal and the CO concentration in the supply air is low, a condition is provided that can cancel the incombustible state.

  When “the CO sensor is abnormal and the CO concentration in the supply air is high”, the above-described self-chamber contamination or the like is suspected, and therefore combustion should not be resumed but a non-combustible state should be maintained.

  The invention according to claim 1, which has been developed based on the above consideration, includes a combustion section provided with a burner, a blower, and a carbon monoxide sensor, and fuel is supplied to the combustion section by the blower while supplying air to the combustion section. The heat generated by burning the gas is supplied to the desired application, the carbon monoxide contained in the exhaust gas is monitored by a carbon monoxide sensor, and the concentration and / or constant value of the carbon monoxide contained in the exhaust gas is greater than or equal to a certain value. In the combustion device that stops combustion in the combustion section when the above integrated concentration is reached, the carbon monoxide sensor has a detection value P that changes according to the surrounding carbon monoxide concentration. The ambient carbon monoxide concentration is detected by comparison with the zero reference Pstd, and the carbon monoxide sensor has a hygroscopic property, and has a characteristic that the detection value P varies due to moisture absorption. Yes And a drying processing function for drying the carbon monoxide sensor, and a pre-processing detection value Pbef in the non-burning state before the drying processing and a post-processing detection value Paft in the non-burning state after the drying processing. If the difference between the pre-processing detection value Pbef and the post-processing detection value Paft is equal to or greater than a certain value, and the difference between the post-processing detection value Paft and the zero reference Pstd is within a predetermined range, an incombustible state is detected. The combustion apparatus is characterized by being released.

According to the present invention, “when carbon monoxide contained in exhaust gas is monitored by a carbon monoxide sensor, the concentration of carbon monoxide contained in the exhaust gas reaches a certain value or higher and / or an accumulated concentration equal to or higher than a certain value. , A combustion apparatus that stops combustion in the combustion section to make the combustion impossible state.
Here, “when the concentration of carbon monoxide contained in the exhaust gas reaches a certain level or higher” assumes a situation where the combustion state deteriorates rapidly and the exhaust gas contains a large amount of carbon monoxide. In such a case, a combustion apparatus having a function of making combustion impossible is assumed.

In addition, “when the carbon monoxide contained in the exhaust gas has reached a certain concentration or more” is assumed to be a combustion device having a function for eliminating the concern that carbon monoxide is concentrated indoors. Yes.
That is, in the unlikely event that the exhaust path is corroded and the exhaust gas leaks into the room, the carbon monoxide concentration in the room is the time when the exhaust gas is discharged, the amount of leaked exhaust gas, Of carbon monoxide, the volume of the leaked room, and the ventilation of the room. Therefore, there is a combustion apparatus having a function of monitoring the integrated concentration (synonymous with the integrated amount) of carbon monoxide contained in the exhaust gas, and setting it to a non-combustible state when this exceeds a certain threshold value. The present invention is also directed to a combustion apparatus having this configuration. Actually, both “when the carbon monoxide contained in the exhaust gas reaches a concentration above a certain value” and “when the carbon monoxide contained in the exhaust gas reaches an accumulated concentration above a certain value” Many combustion devices are monitored.

  The detection value P may be the signal output itself such as the voltage output as described above, or may be detected as some numerical value by performing some calculation or processing. For example, the density may be directly output as a numerical value.

The combustion apparatus of the present invention has a drying function for drying the CO sensor. By drying the CO sensor, malfunction caused by relative humidity (hereinafter simply referred to as humidity) is eliminated.
In the combustion apparatus of the present invention, the pre-processing detection value Pbef in the non-burning state before the drying process and the post-processing detection value Paft in the non-burning state after the drying process are detected. Then, the difference between the pre-processing detection value Pbef and the post-processing detection value Paft is observed. Here, the detection value Pbef before drying in the non-burning state before the drying process is a detection value P that may have malfunctioned due to the influence of humidity, and the detection value Paft after processing is the normal detection value P It is.

  Therefore, if there is no difference between the detection value Pbef before processing and the detection value Paft after processing, it is considered that the detection value P so far accurately reflects the concentration of carbon monoxide during combustion. On the contrary, if there is a difference between the detected value Pbef before processing and the detected value Paft after processing, the CO sensor is malfunctioning due to the influence of humidity, and the detected value P before the combustion stop is As a result, the CO sensor malfunctioned, and the concentration was higher than the original value.

Further, as described above, the post-treatment detection value Paft is a detection value in a state where there is no malfunction caused by humidity, and thus indicates the carbon monoxide concentration in the current environment. That is, the post-processing detection value Paft reflects the current carbon monoxide concentration in the supply air.
Accordingly, if there is a large difference between the detected value Paft after processing and the zero reference output Pstd, it indicates that carbon monoxide is included in the supply air. Conversely, if there is no difference between the detected value Paft after processing and the zero reference output Pstd, it indicates that the carbon monoxide in the supply air is low.
Therefore, in the case where “the difference between the pre-processing detection value Pbef and the post-processing detection value Paft is greater than or equal to a certain value and the difference between the post-processing detection value Paft and the zero reference output Pstd is within a predetermined range” Among these combinations, “the CO sensor is abnormal and the CO concentration in the supply air is low”.
The combustion apparatus of the present invention states that “the difference between the pre-processing detection value Pbef and the post-processing detection value Paft is greater than or equal to a certain value, and the difference between the post-processing detection value Paft and the zero reference output Pstd is within a predetermined range”. By confirming, it is confirmed that “the CO sensor is abnormal and the CO concentration in the supply air is low”, and the incombustible state is canceled.

According to the second aspect of the present invention, the operation detection value Pdri immediately before or after the combustion is stopped.
After the combustion is stopped, the operation of the blower is continued to scavenge the combustion section, and the detected value of the carbon monoxide sensor after the scavenging is set to the detected value Pbef before processing, and the detected value Pdri during operation and the zero reference Pstd And the difference Db between the pre-processing detection value Pbef and the post-processing detection value Paft, the non-combustible state is canceled as an additional condition that the difference Dc between Da and Db is within a specified value. The combustion apparatus according to claim 1.

The present invention eliminates the only remaining concerns. That is, although it is rare, the condition described in claim 1 is satisfied even if “the CO sensor is abnormal and the exhaust gas obstruction occurs at the same time”. However, “when the CO sensor is abnormal and exhaust blockage occurs at the same time” is an abnormal supply of air, so the combustion impossible state should be maintained.
Therefore, the present invention detects the operating detection value Pdri immediately before the combustion stop or immediately after the combustion stop, and obtains the difference Da between the operation detection value Pdri and the zero reference output Pstd. This difference Da indicates the carbon monoxide concentration including an extra amount due to malfunction caused by the humidity effect of the CO sensor. That is, the difference Da between the operating detection value Pdri and the zero reference output Pstd is the sum of the true density Cr and the density Cg added due to malfunction.
In the present invention, the difference Db between the detection value Pbef before processing and the detection value Paft after processing is obtained. This difference Db is a density Cg added due to a malfunction due to humidity.
Therefore, the difference Dc between the two indicates the true density Cr. If the value of the true concentration Cr is low, there is no concern about exhaust blockage or the like. Therefore, in the present invention, regarding the difference Da between the operating detection value Pdri and the zero reference output Pstd and the difference Db between the pre-processing detection value Pbef and the post-processing detection value Paft, the difference Dc between them is within a specified value. As an additional condition, cancel the incombustible state. Therefore, in the present invention, the non-combustible state is canceled with an additional condition that the true carbon monoxide concentration Cr is within a specified value.

  According to a third aspect of the present invention, when the difference between the detected value Paft after processing and the detected value Pbef before processing is small, the combustion inability state is maintained. It is.

  When “the difference between the detected value Paft after processing and the detected value Pbef before processing is small”, it is considered that there was no malfunction due to the humidity effect of the CO sensor. “When the difference between the detected value Paft after processing and the detected value Pbef before processing is small” corresponds to “when the CO sensor is normal and the CO concentration in the supply air is low” in the combination of the four patterns described above. In this state, the CO sensor detects a high concentration of carbon monoxide. Since a combustion abnormality has occurred, the combustion should not be resumed, and the incombustible state is maintained.

  According to a fourth aspect of the present invention, when the difference between the post-processing detection value Paft and the zero reference output Pstd is large, the non-combustible state is maintained. It is a combustion device.

  “When the difference between the post-processing detection value Paft and the zero reference output Pstd is large” is a case where a supply air abnormality is suspected. “When the difference between the post-processing detection value Paft and the zero reference output Pstd is large”, among the combinations of the above four patterns, “when the CO sensor is normal and the CO concentration in the supply air is high”, “ This is equivalent to the case where the CO sensor is abnormal and the CO concentration in the supply air is high, and there is a high possibility that there is an abnormality in the supply / exhaust system. To do.

  The invention according to claim 5 is characterized in that, when canceling the non-combustible state, the zero reference output Pstd is corrected in a direction in which the detected value of the concentration decreases. It is a combustion device.

  In the present invention, when canceling the non-combustible state, the zero reference output Pstd is corrected in the direction in which the detected concentration value decreases. That is, the zero reference output Pstd is corrected in anticipation of the malfunction of the CO sensor, so that unnecessary unnecessary combustion stops are reduced thereafter.

  A sixth aspect of the present invention is the combustion apparatus according to any one of the first to fifth aspects, wherein the drying process is performed by heating the carbon monoxide sensor.

  In the combustion apparatus of the present invention, the CO sensor can be dried by a simple method.

  The invention according to claim 7 is the combustion apparatus according to any one of claims 1 to 6, wherein the detected value is a signal output of a carbon monoxide sensor.

  Signal output includes analog output such as voltage output and current output, and digital output such as pulse. According to the present invention, the circuit configuration is simple and there are few failures.

  The invention according to claim 8 is provided with a combustion section provided with a burner, a blower, and a carbon monoxide sensor, and the heat generated by burning fuel with the burner while supplying air to the combustion section by the blower is desired. When the carbon monoxide contained in the exhaust gas is monitored with a carbon monoxide sensor, and the concentration of carbon monoxide contained in the exhaust gas reaches a certain value and / or an integrated concentration above a certain value And a combustion apparatus control method for stopping combustion in the combustion section to make the combustion impossible state, comprising a drying process step for drying the carbon monoxide sensor, and a detected value Pbef before the process in the non-combusted state before the drying process. The detected value Paft after the drying process is compared with the detected value Paft in the non-combustion state, and the detected value is assumed when the difference between the two is not less than a certain value and the detected value Paft and the carbon monoxide concentration are low. And the ratio To the condition that the difference therebetween is within a predetermined in a control method of the combustion apparatus, characterized in that to release the combustion impossible state.

  According to the control method for a combustion apparatus of the present invention, it is possible to cancel the incombustible state after confirming appropriate conditions.

  The combustion apparatus and the control method for the combustion apparatus of the present invention determine whether or not there is a malfunction due to the humidity effect of the CO sensor, and if the combustion is impossible due to the malfunction of the CO sensor, the combustion is impossible. Is released. Therefore, the combustion apparatus adopting the present invention is easy to use. Moreover, in this invention, after confirming appropriate cancellation | release conditions, a combustion impossible state is cancelled | released, Therefore Safety is high.

It is a conceptual diagram of embodiment of this invention. It is a flowchart of the combustion apparatus of embodiment of this invention.

Embodiments of the present invention will be further described below. The combustion apparatus 1 of this embodiment is installed in the building 2 like FIG. 1, and comprises a part of hot-water supply / heating apparatus 3. As shown in FIG.
The combustion apparatus 1 has a housing 5 that forms an outer shell. A hot water can 6 and a heating can 7 are built in the housing 5. Blowers 10 and 11 are connected to the hot water supply can 6 and the heating can 7 respectively. Also, the hot water supply can 6 and the heating can 7 are respectively provided with burners 15 and 16, and combustion parts 17 and 18 are formed therein.

A heat exchanger (not shown) is incorporated on the downstream side of the combustion units 17 and 18. The heat exchanger can recover not only sensible heat but also latent heat.
An exhaust collecting portion 20 is provided further downstream of the heat exchanger, and the ends of the hot water supply can 6 and the heating can 7 are joined.
A CO sensor 21 is built in the exhaust collecting portion 20. The CO sensor 21 is a known catalytic combustion type carbon monoxide sensor. The CO sensor 21 outputs a detection value P corresponding to the carbon monoxide concentration in the exhaust collecting unit 20. More specifically, a voltage corresponding to the carbon monoxide concentration is output as the detection value P. The detected value (voltage) has a positive correlation with the carbon monoxide concentration. When the carbon monoxide concentration increases, the detected value (voltage) P increases. The CO sensor 21 has a characteristic of outputting a detection value (voltage) P higher than the actual carbon monoxide concentration by absorbing moisture.
Further, by increasing the amount of current supplied to the CO sensor 21, the CO sensor 21 itself can be heated and dried. That is, the CO sensor 21 has a drying processing function.

An exhaust duct 22 is connected to the downstream side of the exhaust collecting portion 20. It protrudes into the room 23 where the combustion apparatus 1 is installed, and further passes through the adjacent room 25 and is connected to the outdoor 26.
Further, there is an air supply duct 27 laid along the same path, and one end of the air supply duct 27 is opened in the housing 5.

  The combustion apparatus 1 of this embodiment starts the air blowers 10 and 11, supplies air to the combustion parts 17 and 18, generates a flame with the burners 15 and 16, and heats the heat exchanger which is not shown in figure. The heat exchanger collects not only sensible heat but also latent heat, and the remaining exhaust gas has a temperature of about 50 to 80 degrees Celsius. Therefore, the humidity in the exhaust collecting part 20 is high.

  The exhaust gas flows through the exhaust duct 22 and is exhausted to the outdoors 26. On the other hand, when the exhaust gas is exhausted, the pressure in the housing 5 decreases, and air flows into the housing 5 from the outdoor 26 via the air supply duct 27.

In the combustion device 1 of the present embodiment, combustion control is performed by a control device (not shown). In particular, in the combustion apparatus 1 of the present embodiment, the carbon monoxide concentration in the exhaust gas is monitored by the CO sensor 21 during combustion. When the concentration of carbon monoxide in the exhaust gas exceeds a certain value, the combustion is forcibly stopped, and thereafter the burner is not ignited even if there is a combustion request. That is, when the exhaust gas carbon monoxide concentration exceeds the threshold value, combustion becomes impossible.
Further, in the combustion apparatus 1 of the present embodiment, the integrated concentration of exhaust gas is calculated, and when the integrated concentration reaches a certain value, the combustion is forcibly stopped in the same manner, and thereafter the burner is not ignited even if there is a combustion request. It becomes a state. That is, when the integrated concentration of the exhaust gas exceeds the threshold value, the combustion becomes impossible.

However, the combustion apparatus 1 of the present embodiment has a function of canceling the incombustible state under certain conditions.
Hereinafter, this function will be described with reference to the flowchart of FIG.
In the combustion apparatus 1 of this embodiment, the zero reference of the CO sensor 21 is determined at the factory shipment stage. That is, in this embodiment, the zero reference (voltage) of the CO sensor 21 is set to Pstd volts and stored in a storage device (not shown).
In step 1, the zero reference Pstd is read from a storage device (not shown).

In the combustion apparatus 1 of the present embodiment, as described above, if the carbon monoxide concentration of the exhaust gas exceeds the threshold value or the integrated concentration of the exhaust gas exceeds the threshold value during combustion, the combustion device 1 becomes incombustible.
That is, when it is confirmed in step 2 that combustion has started, and in step 3 it is confirmed that the exhaust gas carbon monoxide is in an excessive state, the routine proceeds to step 4 where the combustion is forcibly stopped. Even if there is a further combustion request, the burner is not ignited.

In the subsequent step 5, the detection value (operation detection value Pdri) of the CO sensor 21 immediately after the combustion is stopped is stored. That is, the CO sensor 21 detects the carbon monoxide concentration immediately after the combustion is stopped, and stores this detected value (operation detected value Pdri) in a memory of a control device (not shown). If the CO sensor 21 absorbs moisture and malfunctions, the operating detection value Pdri is a voltage corresponding to the concentration of carbon monoxide contained in the original exhaust gas in addition to the zero reference (voltage) Pstd. And the voltage includes the extra due to malfunction.
That is, the content of the operating detection value Pdri is as shown in Equation 1.

Pdri = Pstd + Va + Vb Formula 1
Pdri: Detection value during operation (voltage)
Pstd: Zero reference (voltage)
Va: voltage corresponding to the concentration of carbon monoxide contained in the original exhaust gas Vb: voltage added due to malfunction

In subsequent step 6, scavenging of the hot water supply can 6 and the heating can 7 is performed. This process is performed using a process called post-purge. That is, even after the combustion of the burners 15 and 16 is stopped, the rotation of the blowers 10 and 11 is maintained for a certain time. As a result, all the exhaust gas remaining in the hot water supply can 6 and the heating can 7 is discharged, and the CO sensor 21 is exposed to fresh air supply.
In step 7, the detection value (pre-processing detection value Pbef) of the CO sensor 21 after the post purge is stored. That is, the CO sensor 21 detects the carbon monoxide concentration after the post purge, and stores this detected value (pre-processing detected value Pbef) in a memory of a control device (not shown).
If the CO sensor 21 absorbs moisture and malfunctions, the pre-treatment detection value Pbef has a voltage corresponding to the concentration of carbon monoxide contained in the supply air in addition to the zero reference (voltage) Pstd. The voltage includes the extra amount due to malfunction.
That is, the content of the pre-processing detection value Pbef is as shown in Equation 2.

Pbef = Pstd + Vc + Vb Equation 2
Pbef: Detection value (voltage) before processing
Pstd: Zero reference (voltage)
Vc: voltage corresponding to the concentration of carbon monoxide contained in the supply air Vb: voltage added due to malfunction

  In subsequent step 8, the CO sensor 21 is dried. Specifically, the energization amount to the CO sensor 21 is increased, the temperature of the CO sensor 21 is increased, and the adsorbed moisture is evaporated.

In the subsequent step 9, the detected value (post-process detected value Paft) of the CO sensor 21 after the drying process is stored. That is, after the CO sensor 21 is heated, the carbon sensor 21 detects the carbon monoxide concentration, and this detection value (post-processing detection value Paft) is stored in a memory of a control device (not shown).
Even if the CO sensor 21 absorbs moisture and malfunctions, the post-processing detection value Paft is a voltage that accurately represents the voltage corresponding to the concentration of carbon monoxide contained in the supply air.
That is, the content of the post-processing detection value Paft is as shown in Equation 3.

Paft = Pstd + Vc Equation 3
Paft: Detection value after processing (voltage)
Pstd: Zero reference (voltage)
Vc: voltage corresponding to the concentration of carbon monoxide contained in the supply air

  In step 10, the zero reference Pstd is subtracted from the post-processing detection value Paft to obtain an absolute value. What is the calculation? It is as Formula 4.

| Paft−Pstd | = | Pstd + Vc | −Pstd = Vc Equation 4
Paft: Detection value after processing (voltage)
Pstd: Zero reference (voltage)
Vc: voltage corresponding to the concentration of carbon monoxide contained in the supply air

This Vc is a voltage corresponding to the concentration of carbon monoxide contained in the supply air, and should originally be zero or a value close to zero.
However, if this value exceeds a certain value A, carbon monoxide is included in the supply air, and the supply air is abnormal, and self-contamination is suspected. Therefore, when the voltage Vc corresponding to the concentration of carbon monoxide contained in the supply air is equal to or higher than a certain threshold value A, the process proceeds to step 16 to maintain the incombustible state.
On the other hand, if the voltage Vc is less than the certain threshold A, the process proceeds to step 11.

  In step 11, the detection value Paft after processing is subtracted from the detection value Pbef before processing to obtain an absolute value. What is the calculation? It is as Formula 5.

| Pbef−Paft | = | (Pstd + Vc + Vb) − (Pstd + Vc) | = Vb
... Formula 5
Pbef: Detection value (voltage) before processing
Paft: Detection value after processing (voltage)
Vc: voltage corresponding to the concentration of carbon monoxide contained in the supply air Vb: voltage added due to malfunction

As apparent from Equation 5, the voltage Vb for the extra due to the malfunction is calculated by subtracting the detection value Paft after the processing from the detection value Pbef before the processing. When the additional voltage Vb due to malfunction is small, malfunction due to the humidity effect of the CO sensor 21 is not recognized, and it should be considered that abnormal combustion has actually occurred.
Accordingly, when the voltage Vb is equal to or lower than the certain threshold value B, the process proceeds to step 16 and the combustion impossible state is maintained.
On the other hand, if the voltage Vb exceeds a certain threshold B, it is considered that the CO sensor 21 has malfunctioned due to the influence of humidity, and the process proceeds to step 12.

In step 12, the difference Da between the operating detection value Pdri and the zero reference output Pstd, the difference Db between the pre-processing detection value Pbef and the post-processing detection value Paft, and the difference Dc between Da and Db are obtained.
What is the calculation? It is as Formula 6.

| Da-Db | = | Pdri-Pstd |-| Pbef-Paft |
= | (Pstd + Va + Vb) −Pstd | − | (Pstd + Vc + Vb) − (Pstd + Vc) |
= | Va + Vb | − | Vb |
= Va
= Dc Formula 6

Pdri: Detection value during operation (voltage)
Pstd: Zero reference (voltage)
Pbef: Detection value (voltage) before processing
Paft: Detection value after processing (voltage)
Va: voltage corresponding to the concentration of carbon monoxide contained in the original exhaust gas Vc: voltage corresponding to the concentration of carbon monoxide contained in the supply air Vb: voltage added due to malfunction

That is, Dc (Va) is a voltage corresponding to the concentration of carbon monoxide contained in the original exhaust gas. When Va is high, it indicates that the concentration of carbon monoxide contained in the exhaust gas is actually high, so it should be considered that abnormal combustion has actually occurred. Therefore, when Dc (Va) is larger than the predetermined threshold value C, the routine proceeds to step 16 and the combustion impossible state is maintained.
Note that the case where the process reaches step 16 via step 12 is considered to be “a case where the CO sensor is abnormal and exhaust blockage or the like occurs simultaneously”.
If step 12 is YES, it can be determined that the combustion has been stopped simply due to a malfunction due to the humidity effect of the CO sensor 21, and therefore the process of canceling the incombustible state is entered.
In the present embodiment, the zero reference (voltage) Pstd is corrected before canceling the non-combustible state. That is, the process goes to step 13 to store the additional voltage Vb due to malfunction. The voltage Vb is calculated by Equation 5 described above.

Then, the process proceeds to step 14 where the initial zero reference Pstd is corrected in the direction in which the density detection value decreases. Specifically, a new zero reference Pstd is stored by multiplying the additional voltage Vb due to malfunction caused by humidity effects by a coefficient a of 1 or less as a new zero reference Pstd.
Then, the process proceeds to step 15 to cancel the incombustible state.

  In the present embodiment, the following calculation is performed in Step 10 to determine whether or not the concentration of carbon monoxide contained in the supply air is equal to or less than the threshold value A. That is, the following judgment was made.

| Paft−Pstd | ≦ A Equation 7
Paft: Detection value after processing (voltage)
Pstd: Zero reference (voltage)
A: Constant

  In the following Step 11, it was determined whether or not the error due to water absorption was equal to or greater than the threshold value B. That is, the following judgment was made.

| Pbef−Paft | ≧ B (8)
Pbef: Detection value (voltage) before processing
Paft: Detection value after processing (voltage)
B: Constant

  However, the order of calculation is arbitrary, and these may be reversed. In short, in the present embodiment, determination is performed according to the following matrix table. However, depending on the order of calculation, there may be a combination in the next matrix table that does not have an opportunity for determination. For example, according to the order of the flowcharts described above, when the concentration of carbon monoxide contained in the supply air exceeds the threshold A, there is no opportunity to determine whether or not the error due to water absorption is greater than or equal to the threshold B.

  In a subsequent step, the true concentration of carbon monoxide contained in the exhaust gas was calculated, and it was determined whether or not this concentration was equal to or less than a threshold value C. That is, the following judgment was made. This process is also in no particular order.

| Da−Db | = | Pdri−Pstd | − | Pbef−Paft | ≦ A Equation 9
Pdri: Detection value during operation (voltage)
Pstd: Zero reference (voltage)
Pbef: Detection value (voltage) before processing
Paft: Detection value after processing (voltage)

Finally, the magnitude relationship between the thresholds A, B, and C will be described.
The above-described threshold value A is a limit value of the carbon monoxide concentration that is allowed to be included in the supply air. The threshold value B is a criterion for determining whether or not the CO sensor 21 malfunctions due to the influence of humidity. The threshold value C is a limit value of the carbon monoxide concentration allowed to be included in the exhaust gas.
Therefore, the threshold value B is the smallest, and then the threshold value A is large. The threshold value C is considerably larger than these.

  Specifically, the threshold A is about 50 ppm to 100 ppm. The threshold B is about 100 ppm to 200 ppm. The threshold value C is about 300 ppm to 500 ppm.

DESCRIPTION OF SYMBOLS 1 Combustion apparatus 2 Building 3 Hot water supply / heating apparatus 5 Case 6 Hot water supply can body 7 Heating can body 10, 11 Blower 15, 16 Burner 17, 18 Combustion part 20 Exhaust collecting part 21 CO sensor 22 Exhaust duct

Claims (8)

It is equipped with a combustion section equipped with a burner, a blower, and a carbon monoxide sensor. While supplying air to the combustion section with the blower, the heat generated by burning the fuel with the burner is supplied to the desired application and included in the exhaust gas. Carbon monoxide is monitored by a carbon monoxide sensor, and if the carbon monoxide contained in the exhaust gas reaches a concentration above a certain value and / or an integrated concentration above a certain value, the combustion in the combustion section is stopped. In the combustion device that makes the combustion impossible,
In the carbon monoxide sensor, the detection value P changes according to the surrounding carbon monoxide concentration, and the surrounding carbon monoxide concentration is detected by comparison with the zero reference Pstd.
The carbon monoxide sensor has a property of having a hygroscopic property and a detection value P fluctuates by absorbing moisture.
Provided with a drying treatment function for drying the carbon monoxide sensor,
A pre-processing detection value Pbef in the non-burning state before the drying process and a post-processing detection value Paft in the non-burning state after the drying process are detected;
Canceling the non-combustible state on condition that the difference between the detected value Pbef before processing and the detected value Paft after processing is a certain value or more and that the difference between the detected value Paft after processing and the zero reference Pstd is within a predetermined range. Combustion device characterized by. The detection value Pdri at the time of operation immediately before the combustion stop or immediately after the combustion stop is detected, and after stopping the combustion, the operation of the blower is continued to scavenge the combustion part, and the detection value of the carbon monoxide sensor after the scavenging is detected before the processing. Let the value Pbef be
Regarding the difference Da between the operating detection value Pdri and the zero reference Pstd and the difference Db between the pre-processing detection value Pbef and the post-processing detection value Paft, an additional condition is that the difference Dc between Da and Db is within a specified value. The combustion apparatus according to claim 1, wherein the incombustible state is canceled.   The combustion apparatus according to claim 1 or 2, wherein when the difference between the post-processing detection value Paft and the pre-processing detection value Pbef is small, the combustion impossible state is maintained.   The combustion apparatus according to any one of claims 1 to 3, wherein when the difference between the post-processing detection value Paft and the zero reference Pstd is large, a combustion impossible state is maintained.   The combustion apparatus according to any one of claims 1 to 4, wherein when canceling the incombustible state, the zero reference Pstd is corrected in a direction in which the detected value of the concentration decreases.   The combustion apparatus according to claim 1, wherein the drying process is performed by heating the carbon monoxide sensor.   The combustion apparatus according to claim 1, wherein the detected value is a signal output of a carbon monoxide sensor. It is equipped with a combustion section equipped with a burner, a blower, and a carbon monoxide sensor. While supplying air to the combustion section with the blower, the heat generated by burning the fuel with the burner is supplied to the desired application and included in the exhaust gas. Carbon monoxide is monitored by a carbon monoxide sensor, and if the carbon monoxide contained in the exhaust gas reaches a concentration above a certain value and / or an integrated concentration above a certain value, the combustion in the combustion section is stopped. In the control method of the combustion device to make the combustion impossible state,
A drying process for drying the carbon monoxide sensor;
The pre-treatment detection value Pbef in the non-burning state before the drying treatment and the post-treatment detection value Paft in the non-burning state after the drying treatment are compared, and the difference between the two is not less than a certain value.
Combustion characterized in that the non-combustible state is canceled on the condition that the post-treatment detection value Paft is compared with a detection value assumed when the carbon monoxide concentration is low and the difference between the two is within a predetermined range. Control method of the device.

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