JP6186983B2 - Combustion device and hot water supply device - Google Patents

Description

  The present invention relates to a combustion apparatus and a hot water supply apparatus, and more particularly to a combustion apparatus and a hot water supply apparatus including a CO sensor.

  A combustion apparatus that generates heat by fuel combustion can be configured to detect a combustion failure such as incomplete combustion of fuel by providing a CO sensor in an exhaust gas path or the like. Typically, a gas water heater installed indoors is configured to include a CO sensor.

  The CO sensor has a configuration in which, for example, a platinum wire coil is coated with a catalyst such as aluminum oxide, dried and fired. In such a CO sensor, if contaminants adhere to the surface, an error occurs in the sensor output.

  For example, in Japanese Patent Laid-Open No. 2013-76483 (Patent Document 1), in order to eliminate the output error of the CO sensor, the CO sensor is periodically heat cleaned, and the zero point of the sensor output is immediately after the heat cleaning. It is described that correction is performed.

JP 2013-76483 A

  In general, the zero correction of the CO sensor is periodically executed at a constant cycle (for example, a cycle of around several hours). In order to increase the detection accuracy of the CO sensor, it is important to perform zero point correction in a state where the CO concentration component at the CO sensor placement position is substantially zero.

  Therefore, it is necessary to sufficiently scavenge the exhaust passage in which the CO sensor is arranged between the end of fuel by the combustion device and the execution of the CO sensor zero point correction. On the other hand, if the temperature of the components of the combustion device decreases due to excessive scavenging, there is a concern that the thermal efficiency decreases when fuel is burned again after scavenging.

  The present invention has been made to solve such problems, and an object of the present invention is to perform scavenging until the start of zero correction of the CO sensor in a combustion apparatus and a hot water supply apparatus having a CO sensor. To do it properly.

  A combustion apparatus according to the present invention comprises a burner for burning fuel, a blower fan for blowing air to the burner, a CO sensor disposed in the exhaust passage of the burner, a correction means, a scavenging means, and an adjusting means. Including. The correction means periodically executes the zero point correction of the CO sensor. The scavenging means scavenges the exhaust passage by blowing air from the blower fan during the period from the end of combustion of the burner to the start of the next zero point correction by the correcting means. The adjusting means changes the amount of scavenging by the scavenging means in accordance with the predicted time from the end of combustion of the burner to the start of the next zero point correction.

  According to the combustion apparatus described above, when the time from the end of combustion of the burner to the zero point correction of the CO sensor is short, there is a problem that the accuracy of the zero point correction decreases due to a shortage of the scavenging amount, and the zero point correction due to the excessive amount of scavenging amount By avoiding the problem that the thermal efficiency is lowered when the combustion operation is performed again by the time, scavenging until the start of the CO zero point correction can be performed appropriately.

  Preferably, the adjusting means sets the scavenging amount to the first value when the predicted time is longer than the reference time, and is larger than the first value when the predicted time is shorter than the reference time. Means for setting the scavenging amount by the scavenging means is included so that the scavenging amount becomes larger as the predicted time becomes shorter in the range.

  In this way, when the time from the end of combustion of the burner to the zero correction of the CO sensor is long, the scavenging amount is suppressed to a certain time, so that the temperature of the components of the combustion device excessively decreases, thereby causing the next burner. It can prevent that the thermal efficiency at the time of combustion falls. Furthermore, when the time until the zero point correction is short, it is possible to avoid a decrease in the accuracy of the zero point correction by increasing the scavenging amount.

  Preferably, the combustion apparatus further includes a standby unit. The standby means waits for the zero point correction so that the combustion request by the burner is prioritized over the zero point correction. The adjusting means has means for setting the scavenging amount by the scavenging means to a maximum value when combustion by the burner is completed in a state where the zero point correction is waited by the standby means.

  In this way, the scavenging amount for the zero point correction can be appropriately ensured even when the zero point correction that has been waited immediately after the burner combustion ends is performed.

  More preferably, the scavenging means has means for adjusting the post-purge time after completion of combustion by the burner according to the scavenging amount determined by the adjusting means.

  In this way, it is possible to appropriately secure the scavenging amount for the zero point correction by adjusting the post-purge time that is executed every time the burner burns.

  Preferably, the scavenging means performs a first scavenging amount by post-purge after completion of combustion by the burner and second scavenging by causing the blower fan to perform scavenging operation between the end of post-purge and the start of zero point correction. Means for securing the scavenging amount determined by the adjusting means by the sum of the amounts is included. The first scavenging amount is constant regardless of the prediction time, while the second scavenging amount is variably set according to the prediction time.

  In this way, the scavenging amount for the zero point correction can be appropriately ensured by the post-purge executed each time the burner burns and the scavenging operation before the zero point correction. In particular, since the post-purge time can be fixed to a necessary minimum fixed time without extending for zero point correction, it is possible to prevent a decrease in thermal efficiency during the next burner combustion.

  More preferably, the combustion apparatus further includes rotation speed control means. The rotational speed control means sets the rotational speed of the blower fan when supplying the second scavenging amount to be lower than the rotational speed of the blower fan during post purge.

  If it does in this way, the discomfort given to a user by the operation of the blower fan before the zero point correction of the CO sensor can be reduced.

  The hot water supply apparatus according to the present invention includes any one of the above-described combustion apparatuses and a heat exchanger for increasing the temperature of hot water flowing through the amount of heat generated by the combustion apparatus.

  According to the hot water supply apparatus, scavenging for zero point correction of the CO sensor provided in the exhaust passage of the combustion apparatus can be appropriately executed.

  According to the present invention, in the combustion apparatus and hot water supply apparatus provided with the CO sensor, scavenging up to the start of the zero correction of the CO sensor can be appropriately executed.

It is a schematic block diagram of the gas hot-water supply apparatus 100 containing the combustion apparatus according to embodiment of this invention. It is a conceptual waveform diagram for explaining the output voltage behavior of the CO sensor at the time of zero point correction. It is a conceptual diagram for demonstrating the execution timing of the zero point correction | amendment of CO sensor. It is a conceptual diagram for demonstrating the comparative example of the setting aspect of the post purge time after completion | finish of combustion. It is a conceptual diagram for demonstrating the setting aspect of the post purge time in the combustion apparatus according to this Embodiment. It is a flowchart explaining the control processing procedure of the post purge in the combustion apparatus according to the present embodiment. It is a flowchart explaining the control processing procedure of the post purge in the combustion apparatus according to the modification of this Embodiment. It is a flowchart for demonstrating the scavenging driving | operation at the time of zero point correction | amendment in the combustion apparatus according to the modification of this Embodiment.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or an equivalent part in a figure, and the description shall not be repeated in principle.

  FIG. 1 is a schematic configuration diagram of a gas hot water supply device 100 including a combustion device according to an embodiment of the present invention.

  Referring to FIG. 1, gas hot water supply apparatus 100 includes a burner 10 that burns fuel gas, a blower fan 11, a heat exchanger 12, a CO sensor 20, and a control unit 30. In the gas hot water supply apparatus 100 illustrated in FIG. 1, the burner 10, the blower fan 11, the CO sensor 20, and the control unit 30 constitute a combustion apparatus to which the present invention is applied.

  The blower fan 11 supplies air to the burner 10. The amount of air blown from the blower fan 11 is determined according to the number of fan rotations. The heat exchanger 12 recovers heat from the combustion gas generated by the burner 10 and heats hot water flowing through the heat exchanger 12. Thereby, the gas hot-water supply apparatus 100 can heat the water introduced from the water intake channel, and can discharge hot water.

  The CO sensor 20 is disposed in the exhaust path for the combustion gas from the burner 10. As the CO sensor 20, a known one can be used as appropriate, and for example, a platinum wire coil coated with a catalyst such as aluminum oxide and dried and fired can be applied. When CO is present in the exhaust gas, the output voltage of the CO sensor 20 changes according to the CO concentration based on the principle that the resistance value of the platinum wire coil increases due to the reaction heat with CO. Thereby, the CO concentration can be detected based on the output (output voltage) of the CO sensor 20. The output voltage of the CO sensor 20 is sent to the control unit 30. Further, the CO sensor 20 executes a heat-up process for zero point correction, which will be described later, in accordance with a command from the control unit 30.

  The control unit 30 controls the operation of the components of the gas hot water supply device 100. The control unit 30 is typically configured by a microcomputer in which a predetermined program is stored in advance. Further, the control unit 30 controls the start / stop of combustion of the burner 10 and the amount of fuel gas supplied to the burner 10, and also controls the operation / stop of the blower fan 11 and the number of fan rotations during operation. For example, the rotational speed of the blower fan 10 can be controlled by adjusting the drive voltage of a fan motor (not shown) of the blower fan 11 according to a command from the control unit 30.

  In the gas hot water supply device 100, the zero point correction as described below is periodically executed in order to ensure the detection accuracy of the CO sensor 20.

  FIG. 2 is a conceptual waveform diagram for explaining the output voltage behavior of the CO sensor at the time of zero point correction.

  Referring to FIG. 2, a heat-up process is performed between time t <b> 0 and time t <b> 1 to cause the CO sensor 20 to generate heat by flowing a larger current than normal. Thereby, the contaminant adhering to the sensor surface can be removed. During the heat-up process, the output voltage of the CO sensor increases as the energization amount increases.

  When the heat-up process is completed at time t1, the output voltage of the CO sensor gradually decreases. After completion of the heat-up process, a stability check process for determining whether or not the CO sensor output voltage has stabilized is periodically executed. For example, when the voltage change between cycles becomes smaller than a predetermined value at time t3, the stability check process ends.

  From time t3, zero point correction processing for correcting the zero point corresponding to CO concentration = 0 is executed in accordance with the sensor output voltage after stabilization. By completing the zero point correction process at time t4, the zero point correction by the series of heat-up process, stability check process, and zero point correction process is completed.

  FIG. 3 is a conceptual diagram for explaining the execution timing of the zero point correction of the CO sensor 20.

  With reference to FIG. 3, the zero point correction of the CO sensor 20 is executed every elapse of a fixed correction cycle Tz. For example, the correction cycle Tz is set to about 4 to 5 hours. A new zero point correction execution request is generated at time T1 when the correction cycle Tz has elapsed from time T0 when the previous zero point correction is completed.

  When the execution request for the zero point correction process overlaps with the combustion operation of the burner 10 associated with the hot water supply operation in the gas hot water supply apparatus 100, the combustion operation has priority. Therefore, when the burner 10 is not in a combustion operation at time T1, the zero point correction of the CO sensor 20 is started.

  On the other hand, when the burner 10 is in a combustion operation at time T1, that is, when an execution request for the zero point correction process is generated during the combustion operation, the execution of the zero point correction is awaited. Then, at time T2 after the combustion of the burner 10 is stopped by the end of the combustion operation, the zero point correction of the CO sensor 20 is executed.

  Referring to FIG. 1 again, after the burner 10 is combusted, residual gas containing unburned CO components remains in the exhaust passage. The blower fan 11 is operated with the fuel gas supply to the burner 10 stopped after the burner 10 is combusted so that no trouble occurs in the next burner 10 combustion (particularly during ignition) due to the influence of residual gas. A so-called post purge is performed. The CO component in the exhaust path is also discharged by the post purge.

  As described above, the zero point correction of the CO sensor 20 is executed by associating the sensor output voltage during the zero point correction process with the CO concentration = 0. For this reason, at the time of the zero point correction process, the location where the CO sensor 20 is disposed needs to be filled with clean air containing no CO component. Therefore, during the period from the end of combustion of the burner 10 to the zero point correction of the CO sensor 20, a scavenging operation is required in which the blower fan 11 is operated in a state where the fuel gas supply to the burner 10 is stopped.

  The post-purge and the scavenging operation are common in that the blower fan 11 is operated in a state where the fuel gas supply to the burner 10 is stopped. For this reason, it is understood that the post-purge executed each time the burner 10 burns has the effect of the scavenging operation for the zero point correction. Therefore, the scavenging operation can be executed so as to ensure the accuracy of the zero point correction by appropriately setting the post purge time.

  Hereinafter, the integrated value of the amount of air blown from the blower fan 11 in a state where the fuel gas supply to the burner 10 is stopped between the end of combustion of the burner 10 and the zero point correction is referred to as “scavenging amount”. To do. That is, the integrated value of the amount of air blown from the blower fan 11 by the post purge constitutes at least a part of the scavenging amount.

  FIG. 4 is a conceptual diagram for explaining a comparative example of the setting mode of the post purge time after the end of combustion. In FIG. 4, it is assumed that the fan rotation speed in the post-purge of the blower fan 11 is a constant value. Since the integrated amount of air blown from the blower fan 11 is determined by the product of the operating time of the blower fan 11 and the fan rotation speed, the integrated amount of air blown by post purge (that is, the scavenging amount) is proportional to the post purge time Tp.

  Referring to FIG. 4, the post-purge time Tp is normally set to Tp = Ta in consideration that the residual combustion gas does not adversely affect the next combustion. If the post-purge is performed excessively, the temperature of the heat exchanger 12 is lowered, and there is a concern that the heat efficiency in the heat exchanger 12 is lowered during the next combustion operation. Therefore, it is preferable to stop Ta in the minimum necessary time. In addition, sufficient scavenging is ensured until the zero point correction of the CO sensor 20 even if the ventilation fan 11 is naturally ventilated after the end of the post-purge, even if it is naturally ventilated.

  On the other hand, as shown in FIG. 3, when the combustion operation is being performed at time T1, post purge is executed after the end of the combustion operation, and zero point correction is executed immediately thereafter. For this reason, when the combustion end timing of the burner 10 is after time T1, the post-purge time Tp is set longer than usual in order to sufficiently perform scavenging up to the zero point correction (Tp = Tb, Tb). > Ta). Thereby, even when the zero point correction of the CO sensor 20 is executed immediately after the end of the combustion operation, a sufficient scavenging amount can be secured and the CO concentration = 0 can be obtained. It should be noted that Ta and Tb can be set to appropriate values in advance by an actual machine experiment involving CO concentration measurement.

  However, in the setting example shown in FIG. 4, the post-purge time Tp is not extended and Tp = Ta is set unless the zero point correction is waited due to competition with the combustion operation. For this reason, when the combustion is terminated immediately before time T1, scavenging is not sufficiently performed, and there is a possibility that the zero point correction is executed in a state where the CO concentration is not zero. As a result, an error may occur in the CO concentration detection after the zero point correction. On the other hand, if the post-purge time is uniformly extended to Tb, the scavenging amount becomes excessive, and there is a concern that the thermal efficiency during the next combustion operation is lowered.

  FIG. 5 is a conceptual diagram for illustrating how the post purge time is set in the combustion apparatus according to the present embodiment. Also in FIG. 5, the fan rotation speed in the post purge of the blower fan 11 is assumed to be a constant value, as in FIG.

  Referring to FIG. 5, in the combustion apparatus according to the present embodiment, at the end of combustion of burner 10, post operation is performed in accordance with standby standby time Tx from combustion end timing Tf to the next zero point correction start timing (time T <b> 1). A purge time Tp is set.

  When the standby waiting time Tx is longer than the reference time Tr, Tp = Ta is set as in the normal post purge. Further, when the combustion end timing of the burner 10 is after the time T1, that is, when the standby estimated time Tx ≦ 0, Tp = Tb is set as in FIG.

  On the other hand, in the range of 0 <Tx <Tr, the post purge time Tp is set so that the post purge time Tp becomes longer as the standby standby time Tx becomes shorter in the range of Ta <Tp <Tb. For example, as in the example of FIG. 5, the post-purge time Tp (that is, the scavenging amount) can be set continuously according to a linear function with the standby estimated time Tx as a variable. The function for setting the post-purge time Tp (scavenging amount) can be arbitrary as long as it has a qualitative relationship in which the post-purge time Tp becomes longer as the standby standby time Tx becomes shorter. . For example, the post purge time Tp (scavenging amount) may be set according to a step-like function so that the post purge time T increases stepwise with respect to the decrease in the standby standby time Tx.

  Thereby, even when the standby waiting time Tx until the next zero point correction is short, the scavenging amount can be sufficiently secured, so that the zero point correction accuracy of the CO sensor 20 can be prevented from being lowered. Moreover, in the range of the standby standby time Tx> Tr, it is possible to avoid a decrease in thermal efficiency in the next combustion operation due to an excessive post purge time.

  FIG. 6 is a flowchart for illustrating a post-purge control processing procedure in the combustion apparatus according to the embodiment of the present invention.

  Referring to FIG. 6, when combustion of burner 10 is completed (when YES is determined in S100), control unit 30 performs post-purge by the following steps S110 to S150. On the other hand, except for the combustion end timing (when NO is determined in S100), the processing of steps S110 to S150 is skipped, so that post purge is not executed. Therefore, every time combustion of the burner 10 ends, post-purge by steps S110 to S150 is executed.

  In step S110, the control unit 30 estimates the standby standby time Tx until the next zero point correction. The estimated standby time Tx can be calculated according to the time difference between the combustion end timing Tf in FIG. 5 and the time T1 when the correction cycle Tz has elapsed since the previous zero point correction completion (time T0).

  Further, in step S120, the control unit 30 sets the post-purge time Tp according to the characteristics shown in FIG. 5 according to the estimated standby predicted time Tx. As described above, the scavenging amount for zero point correction of the CO sensor 20 is set according to the post-purge time Tp.

  In step S130, the controller 30 performs the post-purge by operating the blower fan 11 in a state where the supply of the fuel gas to the burner 10 is stopped. Further, in step S140, the control unit 30 determines whether or not the post purge execution time in step S130 exceeds the post purge time Tp set in step S120. The control unit 30 repeatedly performs the post-purging in step S130 until the post-purge time Tp has elapsed (when NO is determined in S140). As a result, the blower fan 11 operates over the post-purge time Tp set in step S120.

  When the post-purge time Tp has elapsed (when YES in S140), the control unit 30 proceeds to step S150 and stops the blower fan 11 to end the post-purge. As a result, during the period from the end of combustion of the burner 10 to the zero point correction of the CO sensor 20, the scavenging amount from the blower fan 11 in a state where the fuel gas supply to the burner 10 is stopped is set according to FIG. It is proportional to the post purge time Tp.

  As described above, according to the combustion apparatus according to the present embodiment, the post-purge time executed at the end of the combustion operation is adjusted in accordance with the scavenging amount necessary for the zero point correction of the CO sensor 20. Can do. As a result, when the time from the end of combustion to the zero point correction is short, the accuracy of the zero point correction decreases due to the lack of the scavenging amount, and the combustion operation is executed again before the zero point correction due to excessive scavenging amount It is possible to avoid the problem of lowering the thermal efficiency at the time and appropriately perform scavenging for CO zero point correction.

[Modification]
In FIG. 6, the embodiment in which the scavenging amount for zero point correction of the CO sensor 20 is ensured by the post-purge executed every time the burner 10 finishes burning has been described. Hereinafter, a modification in which a scavenging amount for zero point correction is ensured by a combination of post-purge at the end of combustion and scavenging operation immediately before zero point correction will be described.

  FIG. 7 is a flowchart illustrating a post-purge control processing procedure in the combustion apparatus according to the modification of the embodiment of the present invention.

  Referring to FIG. 7, in the combustion apparatus according to the modification of the embodiment of the present invention, when combustion of burner 10 is completed (when YES is determined in S <b> 100), control unit 30 performs a predetermined time in step S <b> 105. Perform post-purge. For example, the post purge time in step S105 is set to Ta in FIG. 5 (Tp = Ta). Further, the control unit 30 calculates the standby standby time Tx until the next zero point correction by the same step S110 as in FIG. The calculated standby estimated time Tx is temporarily stored.

  On the other hand, the processing of steps S105 and S110 is skipped except for the combustion end timing (when NO is determined in S100). Therefore, every time combustion of the burner 10 is completed, post-purge for a certain time is executed in steps S105 and S110 so that the residual combustion gas does not adversely affect the next combustion. Furthermore, the stored standby estimated time Tx is updated every time combustion is completed.

  FIG. 8 is a flowchart for illustrating the scavenging operation at the time of zero point correction in the combustion apparatus according to the modification of the present embodiment.

  Referring to FIG. 8, in the combustion apparatus according to the modification of the embodiment of the present invention, control unit 30 determines in step S <b> 200 whether or not a zero point correction start condition is satisfied. For example, if the correction cycle Tz has elapsed since the end of the previous zero point correction and the combustion operation has not been executed, step S200 is determined as YES. Therefore, even if the correction cycle Tz has elapsed since the end of the previous zero point correction, if the burner 10 is in a combustion operation, step S200 is determined to be NO, and zero point correction is not started. Note that the determination in step S200 is also periodically executed when the scavenging amount for zero point correction of the CO sensor 20 is ensured only by the post purge (FIG. 6).

  When the zero point correction start condition is satisfied (when YES is determined in S200), control unit 30 proceeds to step S210 and reads the stored standby estimated time Tx. As described above, since the estimated waiting time Tx stored is updated every post-purge, in step S210, the elapsed time from the end of the last combustion before starting the zero point correction is read out.

  Further, in step S220, the control unit 30 sets the scavenging time Tc according to the read standby prediction time Tx. The scavenging time Tc can be set according to (Tp-Ta) in FIG.

  Further, the control unit 30 performs the scavenging operation by operating the blower fan 11. At this time, since the zero point correction start condition (S200) is satisfied, the supply of the fuel gas to the burner 10 is stopped. In step S240, the control unit 30 determines whether the execution time of the scavenging operation in step S230 exceeds the scavenging time Tc set in step S220.

  Control unit 30 repeatedly executes the scavenging operation in step S230 until scavenging time Tc elapses (NO in S240). Thereby, the ventilation fan 11 operates over the scavenging time Tc set in step S220.

  When the scavenging time Tc elapses (YES in S240), the control unit 30 proceeds to step S250 and stops the blower fan 11 to end the scavenging operation.

  As a result, during the period from the end of combustion of the burner 10 to the zero point correction of the CO sensor 20, the scavenging amount from the blower fan 11 when the fuel gas supply to the burner 10 is stopped is equal to the post-purge time Ta. It is ensured according to the sum of the scavenging time Tc. Therefore, also in the combustion apparatus according to the modification of the present embodiment, the scavenging amount up to the zero point correction can be ensured as in the case where the post purge time Tp is set according to FIG.

  Furthermore, when the scavenging operation is completed, the control unit 30 performs zero point correction in step S260. Thereby, as described with reference to FIG. 2, the heat-up process, the stability check process, and the zero point correction process are executed, and the zero point of the CO sensor 20 is corrected. The scavenging operation in steps S230 and S240 needs to be completed before the zero point correction process, but can also be performed after the heat-up process, that is, during the stability check process.

  As described above, in the combustion apparatus according to the modification of the embodiment, the sum of the scavenging amount by the post purge for a predetermined time and the scavenging quantity by the scavenging operation corresponding to the standby waiting time Tx is the same as the combustion apparatus according to the present embodiment. Equivalent scavenging amount up to zero point correction can be secured. As a result, the temperature of the heat exchanger 12 is prevented from excessively decreasing due to the post purge, and the CO concentration in the vicinity of the CO sensor 20 at the time of zero point correction processing is obtained by the scavenging operation corresponding to the standby standby time Tx. Can be zero. That is, as with the combustion apparatus according to the present embodiment, scavenging for CO zero point correction can be appropriately executed.

  In FIGS. 7 and 8, the post-purge time and the scavenging time are set with the fan rotation speed of the blower fan 11 common to each of the post-purge and scavenging operations. It is also possible.

  For example, in the post-purge executed subsequent to the combustion operation of the burner 10, the user feels uncomfortable even if the fan speed is high, but the fan speed is high during zero point correction that is periodically executed. There is a risk that the user may feel uncomfortable. Therefore, in the combustion apparatus according to the modification of the embodiment, it is preferable to set the rotational speed of the blower fan 11 in the scavenging operation to be lower than the rotational speed of the blower fan 11 in the post purge. In this case, the scavenging time Tc is set longer than (Tp−Ta) set according to the characteristics of FIG. This prevents the user from feeling uncomfortable due to the operation of the blower fan 11 during the zero correction process of the CO sensor.

  In the combustion apparatus according to the present embodiment and its modification, the CO sensor is not limited as long as it can output the sensor with respect to the CO concentration. The burner 10 may be an oil burner, for example, instead of the gas burner. That is, as long as the burner contains a CO component in the exhaust, the fuel can be arbitrary. In addition, the hot water supply apparatus according to the present invention is not necessarily configured as a hot water supply apparatus, and may be configured as a combustion apparatus for heating, for example.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  10 burner, 11 blower fan, 12 heat exchanger, 20 CO sensor, 30 control unit, 100 gas hot water supply device, Ta time, Tc scavenging time, Tf combustion end timing, Tp post purge time, Tr reference time (reference value), Tx standby waiting time, Tz correction cycle.

Claims (7)

A burner for burning the fuel,
A blower fan for blowing air to the burner;
A CO sensor disposed in the exhaust passage of the burner;
Correction means for periodically executing zero correction of the CO sensor;
Scavenging means for scavenging the exhaust passage by blowing air from the blower fan during the period from the end of combustion of the burner to the start of the next zero point correction by the correcting means;
A combustion apparatus comprising: adjusting means for changing a scavenging amount by the scavenging means in accordance with an estimated time from the end of combustion of the burner to the start of the next zero point correction. The adjusting means includes
When the predicted time is longer than the reference time, the scavenging amount is set to a first value, while when the predicted time is shorter than the reference time, the scavenging amount is in a range larger than the first value. The combustion apparatus according to claim 1, further comprising means for setting a scavenging amount by the scavenging means so that the scavenging amount becomes larger as the predicted time becomes shorter. Standby means for waiting for the zero point correction so as to give priority to the combustion request by the burner over the zero point correction;
The adjusting means includes
The means for setting a scavenging amount by the scavenging means to a maximum value when combustion by the burner is finished in a state where the zero point correction is waited by the standby means. Combustion device. The scavenging means includes
The combustion apparatus according to any one of claims 1 to 3, further comprising means for adjusting a post-purge time after completion of combustion by the burner according to a scavenging amount determined by the adjusting means. The scavenging means includes
The sum of the first scavenging amount by post purge after the end of combustion by the burner and the second scavenging amount by scavenging the blower fan between the end of the post purge and the start of the zero point correction. Includes means for securing a scavenging amount determined by the adjusting means,
The first scavenging amount is constant regardless of the prediction time, while the second scavenging amount is variably set according to the prediction time. The described combustion device.   The combustion apparatus according to claim 5, further comprising a rotation speed control means for setting a rotation speed of the blower fan during the scavenging operation to be lower than a rotation speed of the blower fan during the post purge. A combustion apparatus according to any one of claims 1 to 6;
A hot water supply apparatus comprising: a heat exchanger for increasing the temperature of hot water flowing through the amount of heat generated by the combustion apparatus.

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