JP5838634B2 - Combustion device - Google Patents

Description

  The present invention relates to a combustion apparatus used in a water heater, a bath tub, or the like.

  2. Description of the Related Art Conventionally, a combustion apparatus such as a water heater is configured to perform a blockage determination of an air supply / exhaust part before ignition of a burner, for example, disclosed in Patent Document 1 below.

Japanese Patent No. 3054337

  In Patent Document 1, a combustion chamber that accommodates a burner, a supply / exhaust portion that communicates with the combustion chamber, a combustion fan that supplies combustion air to the burner, and a blockage that detects the degree of blockage of the supply / exhaust portion. The degree detection means and the combustion fan are rotated at a predetermined rotation speed before the start of ignition of the burner, and the combustion fan is controlled so that the combustion air amount corresponding to the required combustion amount is obtained during combustion at a target rotation speed. A combustion apparatus is disclosed that includes fan control means and pre-ignition occlusion monitoring means that stops ignition when the degree of occlusion detected before the start of ignition is greater than or equal to a reference value.

  In such a conventional combustion apparatus, when the supply / exhaust passage is blocked, a combustion failure occurs. Therefore, the combustion fan is rotated before the ignition starts in order to stop the operation quickly before the combustion state becomes defective. It is detected based on the number and the current value, and is ignited when there is no problem in the air supply / exhaust path, and is stopped when there is a problem in the air supply / exhaust path. Further, the closed state is monitored during the pre-purge operation of the combustion fan before ignition (paragraph numbers 0064 to 0065).

  Although it is practically desired to set the rotational speed of the combustion fan during the pre-purge operation as low as possible from the viewpoint of noise reduction and low power consumption, as shown in FIG. The fan drive current value becomes too small as a value for determining the blockage of the air supply / exhaust part, and the range of change between the current value with and without blockage and the current value at the time of full blockage is small, so atmospheric conditions such as temperature and humidity, There is a high possibility of erroneous determination due to various factors such as individual differences between apparatuses, elapsed time from the previous combustion operation, aging deterioration of the apparatus, and fluctuations in current supplied from the power supply apparatus. For example, even if the degree of blockage of the air supply / exhaust portion is not problematic in actual use, it may be erroneously determined that ignition is not permitted unless the drive current value of the fan exceeds a predetermined reference value due to the above various factors, Further, if the fan drive current value is detected exceeding a predetermined reference value even though the air supply / exhaust section is blocked, it is erroneously determined that ignition is possible.

  Therefore, in Patent Document 1, when monitoring the pre-ignition blockage, the fan is driven to rotate at a rotational speed (second predetermined rotational speed) greater than the normal pre-purge rotational speed (first predetermined rotational speed). However, this causes a problem that noise and power consumption always increase when the pre-ignition occlusion monitoring operates.

  Therefore, the present invention reduces the rotational speed of the combustion fan as much as possible when determining the blockage of the supply / exhaust portion of the combustion device, while reliably detecting the presence or absence of blockage before the ignition operation when there is a suspicion of blockage. The purpose is to avoid misjudgment.

  In order to achieve the above object, the present invention takes the following technical means.

That is, the present invention determines a combustion chamber that houses a burner, a supply / exhaust portion that communicates with the combustion chamber, a combustion fan that supplies combustion air to the burner, and whether the supply / exhaust portion is blocked. A pre-purge operation of the combustion fan before the ignition of the burner, and a preliminary determination that the supply / exhaust portion is not closed before the blockage determination by the blockage determination unit further comprising a closure preliminary decision means, said closure preliminary determination means, said in the pre-purge operation preliminary determination rows Utotomoni, if it is determined not to be closed by the pre determined moves to the ignition operation of the burner The blockage determining means is configured so that when the preliminary determination does not determine that the blockage is not blocked, the blockage determination means does not shift to the ignition operation of the burner and has a higher rotation speed than the preliminary determination. Line blockage determination of the supply and exhaust portion while rotating the combustion fan Utotomoni, that is configured to transition to the ignition operation of the burner when it is determined not to be closed by the closure determination It is a characteristic (claim 1).

  According to the combustion apparatus of the present invention, in order to determine the degree of blockage of the air supply / exhaust section, first, during the pre-purge operation in which the combustion fan is driven at a relatively low speed, the blockage preliminary determination means clearly blocks the blockage. It is determined whether or not there is no doubt. If it is preliminarily determined that the air supply / exhaust part is not blocked by the blockage preliminary determination means, the blockage degree can be determined to be in the normal range without rotating the combustion fan at a high rotational speed, and noise and power consumption can be reduced. Is planned. On the other hand, for example, if the degree of blockage of the air supply / exhaust section has progressed to some extent, and it is difficult to determine by the blockage preliminary determination unit, the blockage determination unit supplies the combustion fan with the rotation speed being higher. Exhaust blockage determination can be accurately performed, and erroneous determination is reduced. Further, since the preliminary determination by the blockage preliminary determination unit is performed during the pre-purge operation, the preliminary determination can be performed within the pre-purge operation time. Therefore, the ignition operation can be performed early.

Further, the present invention provides a combustion chamber that houses a burner, an air supply / exhaust portion that communicates with the combustion chamber, a combustion fan that supplies combustion air to the burner, and whether or not the air supply / exhaust portion is blocked. In a combustion apparatus comprising a blockage determining means for performing, a target rotational speed is set to a relatively low first rotational speed that is set with priority given to noise and power consumption reduction before the blockage determination by the blockage determining means. It further includes a blockage preliminary determination unit that preliminarily determines that the air supply / exhaust unit is not blocked while controlling the rotation of the combustion fan, and the blockage determination unit is not determined to be blocked by the preliminary determination. Only when the preliminary determination is made , the target rotation speed is set to the second rotation speed higher than that at the time of the preliminary determination, and the blockage determination of the supply / exhaust portion is performed while controlling the rotational drive of the combustion fan. Special that It is an (claim 2). According to this, in order to determine the degree of blockage of the air supply / exhaust section, first, whether the combustion fan is driven at a relatively low speed and is clearly in a state of no suspicion of blockage by the blockage preliminary determination means. Determine whether or not. If it is preliminarily determined that the air supply / exhaust part is not blocked by the blockage preliminary determination means, the blockage degree can be determined to be in the normal range without rotating the combustion fan at a high rotational speed, and noise and power consumption can be reduced. Is planned. On the other hand, for example, when the degree of blockage of the air supply / exhaust portion has progressed to some extent, and it is difficult to make a determination by the blockage preliminary determination unit that performs preliminary determination at a low rotation speed, the combustion fan at a high rotation speed The blockage determination means can accurately determine the blockage of the air supply / exhaust portion in a state where the valve is rotated, and erroneous determination is reduced. Note that the determination operation of either the blockage determination unit or the blockage preliminary determination unit may be performed during the pre-purge operation of the combustion fan before burner ignition.

  In the present invention, the drive control of the combustion fan may be feedback control of the amplitude of the direct current that drives the fan so as to achieve a predetermined target rotational speed, and has already been proposed by the applicant of the present application. As disclosed in Japanese Patent Application Laid-Open No. 9-329331, the fan drive power (control pulse) may be PWM-controlled so as to achieve a predetermined target rotational speed. The target rotational speed may be corrected at any time in consideration of the actual air volume, and the combustion fan may be driven with a predetermined voltage. Further, at the time of preliminary determination by the blockage preliminary determination means, the combustion fan is driven at a predetermined voltage to detect a change in the fan rotation speed due to the blockage degree of the air supply / exhaust portion, and a preliminary determination is made based on the change in the rotation speed. The fan control method is different between the preliminary determination by the blockage preliminary determination unit and the blockage determination by the blockage determination unit, such as feedback control of the fan drive current so that the predetermined rotation speed is obtained when the blockage determination by the determination unit is performed. Also good. That is, the present invention switches the combustion fan drive control to two stages so that the fan rotation speed at the time of preliminary determination by the blockage preliminary determination means and the fan rotation speed at the time of blockage determination by the blockage determination means change greatly. According to such a feature, it is possible to determine that it is not closed quickly with low noise and low power consumption under normal conditions, and to immediately ignite the burner.

  The reference value for the preliminary determination by the blockage preliminary determination means is determined in advance by a test, but it is determined that the blockage is not clearly blocked in consideration of fluctuations in the detected value during actual operation due to the various factors described above. When a suspicion of blockage is recognized, for example, in the vicinity of a threshold value to be determined as blockage, it is preferable to shift to blockage determination by the blockage determination means. In addition, in the same way as the technique described in Patent Document 1 above, the determination of the presence or absence of blockage is performed by previously obtaining the relationship between the blockage degree, the fan rotation speed, the drive current value, and the like by a test, It is possible to determine that there is a blockage when the blockage degree is likely to cause a problem such as a failure.

In the combustion apparatus of the present invention, it may be configured to perform the ignition of the burner when the it is determined not to be closed by either blockage preliminary determination means and the closure determining means. According to such a configuration, if it is determined by the closing preliminary determination means that the combustion fan is in a normal state with no obvious blockage even when the rotation speed is low, the burner ignition operation can be immediately performed. Ignition can be performed quickly.

  Furthermore, it is preferable that both of the blockage determination unit and the blockage preliminary determination unit perform the respective determinations based on the rotational speed of the combustion fan and the drive current value. According to this, the technical correlation between the blockage determination criterion by the blockage determination unit and the blockage determination criterion by the blockage preliminary determination unit is easy to understand, which facilitates design and reduces component parts. In addition, the device configuration can be simplified, and cost reduction and space saving can be achieved. However, the present invention is not limited to this. For example, the blockage determination may be made based on the drive voltage and the rotational speed of the combustion fan, and the drive current of the combustion fan and the supply / exhaust path may be determined. The blockage determination may be performed based on the detection value of the provided air flow sensor, and different standards may be used as the reference for the preliminary determination and the reference for the blockage determination.

  As described above, according to the combustion apparatus of the first aspect of the present invention, in order to determine the degree of blockage of the air supply / exhaust portion, first, during the pre-purge operation in which the combustion fan is driven at a relatively low rotation speed. Thus, it is possible to determine whether or not there is clearly no blockage by the blockage preliminary determination unit. If it is preliminarily determined that the air supply / exhaust part is not blocked by the blockage preliminary determination means, the blockage degree can be determined to be in the normal range without rotating the combustion fan at a high rotational speed, and noise and power consumption can be reduced. Is planned. On the other hand, for example, when the degree of blockage of the air supply / exhaust portion has progressed to some extent, and it is difficult to make a determination by the blockage preliminary determination unit that performs preliminary determination at a low rotation speed, the combustion fan at a high rotation speed The blockage determination means can accurately determine the blockage of the air supply / exhaust portion in a state where the valve is rotated, and erroneous determination is reduced.

  Further, according to the combustion apparatus of the second aspect of the present invention, in order to determine the degree of blockage of the air supply / exhaust section, first, the blockage preliminary determination means in a state where the combustion fan is driven at a relatively low speed. It is determined whether or not there is clearly no blockage. If it is preliminarily determined that the air supply / exhaust part is not blocked by the blockage preliminary determination means, the blockage degree can be determined to be in the normal range without rotating the combustion fan at a high rotational speed, and noise and power consumption can be reduced. Is planned. On the other hand, for example, when the degree of blockage of the air supply / exhaust portion has progressed to some extent, and it is difficult to make a determination by the blockage preliminary determination unit that performs preliminary determination at a low rotation speed, the combustion fan at a high rotation speed The blockage determination means can accurately determine the blockage of the air supply / exhaust portion in a state where the valve is rotated, and erroneous determination is reduced.

  Further, according to the combustion apparatus of the fourth aspect of the present invention, the technical correlation between the blockage determination criterion by the blockage determination unit and the preliminary determination criterion by the blockage preliminary determination unit is easy to understand, In addition to simplification, it is possible to reduce the number of components and the device configuration, thereby reducing costs and saving space.

It is a schematic block block diagram of the combustion apparatus which concerns on one Embodiment of this invention. 3 is a control flowchart of a pre-purge operation of a combustion fan of the combustion apparatus. It is a graph which shows the fluctuation | variation of the drive current value accompanying the target rotation speed setting change of the combustion fan of the combustion apparatus. It is a graph which shows the relationship between the rotation speed of the combustion fan of the combustion apparatus, and a drive current value.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a water heater combustion apparatus 1 according to an embodiment of the present invention, in which a burner 3 and a heat exchanger 4 are accommodated in a combustion chamber of a casing 2 of the combustion apparatus 1. An air supply unit 2a is provided at the lower portion of the casing 2, and a sirocco fan 7 (combustion fan) that is driven to rotate by a fan motor 6 is disposed in the fan case 5 that is connected to the air supply unit 2a. It is installed. An exhaust part 2 b is provided in the upper part of the casing 2. In the present specification, the air supply unit 2a and the exhaust unit 2b are collectively referred to as a “supply / exhaust unit”. It is assumed that the degree of occlusion in is equal to or greater than a reference value.

  A fuel supply pipe 8 for supplying fuel such as gas is connected to the burner 3, and a water supply pipe 9 for supplying water is connected to the heat exchanger 4. A valve 11 is interposed in the fuel supply pipe 8, and the valve 11 is configured to be opened and closed by a hot water supply control unit 12. A part of the hot water supply control unit 12 is constituted by a microcomputer. A spark plug 10 that is actuated by an igniter (not shown) is disposed in the vicinity of the upper flame hole of the burner 3, and the igniter of the spark plug 10 is also controlled by the hot water supply control unit 12. A flow rate sensor 13 is interposed in the water supply pipe 9, and a detection signal of the sensor 13 is input to the hot water supply control unit 12. When water is passed through the water supply pipe 9 by opening the faucet or the like and the water flow is detected by the flow rate sensor 13, the hot water supply control unit 12 supplies an ignition preparation control signal to the fan drive control unit 17 to drive the fan. It waits until an ignition start control signal or an ignition stop control signal is returned from the control unit 17. When an ignition start control signal is supplied from the fan drive control unit 17, the burner 3 is ignited by opening the valve 11 and operating the spark plug 10. On the other hand, when an ignition stop control signal is received from the fan drive control unit 17, the ignition control is interrupted and an alarm is output from a remote controller (not shown).

  Next, the configuration of the control unit of the fan motor 6 will be described. The fan drive power control means 14 supplies the drive power to the fan motor 6 on the basis of a control signal from the fan drive control unit 17, and rotates the fan motor 6. Current value detection means 15 for detecting the drive current value of the fan motor 6 based on the drive power supplied to the fan motor 6 by the drive power control means 14, and fan rotation speed detection means 16 for detecting the rotation speed of the fan motor 6. And a fan drive control unit 17 constituted by a microcomputer. The hot water supply control unit 12 and the fan drive control unit 17 may be configured by a common microcomputer.

  The fan drive power control means 14 may be configured to PWM control the drive power to the fan motor 6 based on the control signal from the fan drive control unit 17, and the control signal from the fan drive control unit 17 A configuration in which the corresponding DC power is supplied to the fan motor 6 can also be adopted.

  The current value detection means 15 can be any appropriate known current sensor. For example, the drive value detection means (16) disclosed in Japanese Patent Application Laid-Open No. 2003-185131 already proposed by the applicant of the present application can be used. A similar configuration may be used. Note that the current value detected by the current value detection means 15 can be detected as an effective current value of the driving power of the fan motor 6 by a current transformer when the fan motor 6 is PWM-controlled. Further, in order to output a current value as a digital signal to the microcomputer, the detected current value can be pulse width modulated using a triangular wave.

  The fan drive control unit 17 controls the pre-purge operation of the fan motor 6 before ignition, and at the time of ignition, the drive speed of the fan 7 and the fan motor 6 is detected by the fan speed detection means with the ignition speed (for example, 3100 rpm) as the target speed. Feedback control is performed based on the fan rotational speed detected by 16. The feedback control at the time of ignition can be performed by a conventionally known method as disclosed in Patent Document 1 and Japanese Patent Laid-Open No. 9-329331.

  FIG. 2 shows a control flow of pre-purge operation control in the present embodiment, and a program for executing each step of the control flow is stored in the storage means in the fan drive control unit 17, and the program is executed by the program. The function of each process is realized.

  When the fan drive control unit 17 receives the ignition preparation control signal from the hot water supply control unit 12, the pre-purge operation control is started. First, in step S1, the fan target rotation speed is set to the first rotation speed with a relatively low rotation. This first rotational speed can be set with priority given to noise reduction and power consumption reduction, and may be the same rotational speed as the ignition rotational speed. The ignition rotational speed is within a range where noise and power consumption do not become excessive. A higher rotational speed may be used. When the target fan speed is set, the fan drive control unit 17 performs feedback control on the fan motor 6 based on the fan speed detected by the fan speed detecting means 16.

  Next, in step S2, the process waits until the first predetermined time has elapsed. This is because immediately after changing the target rotation speed of the fan, as shown in FIG. 3, the fan drive current value also becomes a transient state and exhibits unstable behavior, so the fan drive current value and the fan rotation speed are stable. This is to make it wait until it is done.

  Next, in step S3, the drive current value of the fan motor 6 is measured by the current value detection means 15. The detection value by the current value detection means 15 may be used as it is as the drive current value for the subsequent control. However, in order to make the blockage determination more accurately, the drive current value is appropriately corrected in consideration of various factors. can do.

  Next, in step S4, it is preliminarily determined that the air supply / exhaust section is not blocked based on whether or not the fan drive current value is equal to or less than the first determination current value T1 corresponding to the first rotation speed. If the fan drive current value exceeds the first determination current value, it is determined that the fan is not closed, and the process immediately proceeds to the ignition operation in step S5. On the other hand, if the fan drive current value is equal to or less than the first determination current value, there is a possibility of blockage, and the process proceeds to step S6 in order to perform more reliable blockage determination. Note that the first determination current value can be a blockage threshold value indicated by a one-dot chain line in FIG. 4, and the current value is relatively high due to various factors even though the blockage degree impedes practical use. In order to avoid measurement and thereby shifting to the ignition operation, the first determination current value can be set slightly higher than the blockage threshold value shown in FIG.

  Thus, the fan drive control unit 17 that executes the above steps S1 to S4 realizes a closed preliminary determination unit that preliminarily determines that the air supply / exhaust unit is not closed during the pre-purge operation (low rotation). .

  In step S5, an ignition start control signal is supplied from the fan drive control unit 17 to the hot water supply control unit 12, and fan drive control during normal ignition operation is started.

  In step S6, the target fan speed is set to a relatively high second speed. This second rotation speed is set with priority given to reliable blockage determination. A rotation speed at which reliable blockage determination can be performed is obtained in advance by a test, and the second rotation speed is set based on the test result. It is preferable to do. The ratio between the first rotation speed and the second rotation speed can be set appropriately. For example, the second rotation speed can be 1.2 to 1.5 times the first rotation speed.

  Next, in step S7, the process waits until the second predetermined time elapses as in step S2. The second predetermined time is set to be longer than the first predetermined time in order to make a more reliable blockage determination, whereby the blockage determination is performed in a state where the fan rotation speed and the fan drive current value are more stable. I have to.

  Next, in step S8, the drive current value of the fan motor 6 is measured as in step S3.

  Next, in step S9, it is determined whether or not the supply / exhaust portion is blocked based on whether or not the fan drive current value is equal to or less than a second determination current value T2 corresponding to the second rotational speed. If the fan drive current value exceeds the second determination current value, it is determined that the fan is not closed, and the process proceeds to the ignition operation in step S5. On the other hand, if the fan drive current value is equal to or less than the second determination current value, it is determined that the fan is closed, and the routine proceeds to the ignition interruption operation in step S10.

  Thus, the fan drive control unit 17 that executes the above steps S6 to S10 realizes a blockage determination unit that determines whether the supply / exhaust unit is blocked during the pre-purge operation (high rotation).

  In step S10, an ignition interruption control signal is supplied from the fan drive control unit 17 to the hot water supply control unit 12, and the drive control of the fan motor 6 is also terminated.

  According to the embodiment described above, if the degree of blockage of the air supply / exhaust portions 2a, 2b is in the normal range, it is determined that the blockage preliminary determination means indicates that the fan 7 is not blocked when the pre-purge operation is performed at a relatively low rotational speed. Thus, it is possible to perform preliminary determination and to perform an ignition operation, and it is possible to ignite the burner 3 while ensuring that the air supply / exhaust portions 2a and 2b are not blocked while reducing noise and power consumption. On the other hand, for example, when the degree of blockage of the air supply / exhaust portion has progressed due to long-term use and accurate blockage determination cannot be performed with blockage preliminary determination at a relatively low rotation, the fan 7 is blocked in a state where it is rotationally driven at high rotation. By performing the blockage determination by the determination unit, it is possible to more reliably determine whether or not the blockage degree has no problem in actual use.

  The present invention is not limited to the above-described embodiment, and the design can be changed as appropriate. For example, although the combustion apparatus for hot water heaters was illustrated in the above embodiment, the present invention may be applied to a combustion apparatus for heating equipment such as a gas fan heater. Further, both the preliminary determination by the blockage preliminary determination unit and the blockage determination by the blockage determination unit are performed during the pre-purge operation control, but either one or both may be performed independently of the pre-purge operation. Further, in the above embodiment, both the preliminary determination by the blockage preliminary determination unit and the blockage determination by the blockage determination unit are always performed during the ignition operation. It is also possible to make a determination. Further, the fan driving current value detected by the current value detecting means may be subjected to processing for avoiding erroneous detection such as performing predetermined noise processing. In the above embodiment, the standby processing for the first and second predetermined times is provided in steps S2 and S7 of the control flow shown in FIG. 2, but instead, the detected fan rotation speed value is the fan target rotation. On the condition that the number reaches a stable value, the fan drive current value can be regarded as stable, and the process can proceed to steps S3 and S8 for measuring the next fan current value.

  Further, the present invention can be suitably implemented in a composite water heater as shown in FIG. 2 of JP 2009-287814 A, for example. That is, in this type of combined water heater, in order to operate the hot water supply function and the hot water circulation heating function, the bath reheating function or the bath hot water function independently, two burners, heat exchangers and fans are provided. Combustion chambers are also individually divided, but due to the limitations of installation space, the cross-sectional area of each combustion chamber is relatively narrow and the mounting density of the components increases, so exhaust from the air supply section of each combustion chamber The flow resistance reaching the part becomes relatively high. In addition, since there is no room for the supply / exhaust area, even if the degree of blockage in the supply / exhaust section has progressed, the variation range of the current value is reduced, which increases the possibility of erroneous determination during blockage determination. However, according to the present invention, when the degree of blockage is in the normal range, it is possible to determine that the blockage is not blocked with low noise and low power consumption by the blockage preliminary determination unit, and allow ignition. When there is a suspicion of blockage, it is possible to avoid erroneous determination by controlling the drive of the fan at a sufficiently high rotational speed.

DESCRIPTION OF SYMBOLS 1 Combustion device 2a, 2b Supply / exhaust part 3 Burner 7 Combustion fan 17 Fan drive control part which functions as a blockade judgment means and a blockade preliminary judgment means

Claims (4)

A combustion chamber that accommodates the burner, an air supply / exhaust portion that communicates with the combustion chamber, a combustion fan that supplies combustion air to the burner, and a blockage determination means that determines whether the air supply / exhaust portion is blocked. A combustion apparatus in which a pre-purge operation of the combustion fan is performed before ignition of the burner,
Further comprising a blockage preliminary determination unit that preliminarily determines that the air supply / exhaust unit is not blocked before the blockage determination by the blockage determination unit;
The closure preliminary determining means, wherein the pre-determined rows Utotomoni during the pre-purge operation, if it is determined not to be closed by the pre determined is configured to transition to the ignition operation of the burner,
The blockage determining means does not shift to the ignition operation of the burner when it is not determined by the preliminary determination that the combustion fan is rotated at a higher rotational speed than at the preliminary determination. obstruction determination rows Utotomoni of supply and exhaust unit, a combustion apparatus characterized by being configured to transition to the ignition operation of the burner when it is determined not to be closed by the closure determination. A combustion chamber that accommodates the burner, an air supply / exhaust portion that communicates with the combustion chamber, a combustion fan that supplies combustion air to the burner, and a blockage determination means that determines whether the air supply / exhaust portion is blocked. A combustion apparatus comprising:
Before the blockage determination by the blockage determination means, the target rotational speed is set to the first rotational speed of relatively low rotation that is set with priority on noise and power consumption reduction, and the combustion fan is controlled to rotate. It further comprises blockage preliminary determination means for preliminarily determining that the air supply / exhaust section is not blocked, and the blockage determination means is more than the time of the preliminary determination only when it is determined that the blockage is not blocked by the preliminary determination. A combustion apparatus configured to perform blockage determination of the supply / exhaust unit while controlling a rotational drive of the combustion fan by setting a target rotation speed to a second rotation speed of a high rotation speed. 3. The combustion apparatus according to claim 1, wherein the blockage preliminary determination unit performs the preliminary determination after a first predetermined time has elapsed after setting the target rotational speed of the fan to the first rotational speed. The blockage determining means is configured to block the blockage after a second predetermined time longer than the first predetermined time has elapsed after setting the target rotation number of the fan to a second rotation number larger than the first rotation number. A combustion apparatus configured to make a determination .   4. The combustion apparatus according to claim 1, wherein each of the blockage determination unit and the blockage preliminary determination unit performs the determinations based on a rotational speed and a drive current value of the combustion fan. Combustion device.

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