JP2018013289A - Combustion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion apparatus capable of performing smooth operation by distinctly determining presence of air to an exhaustion passage and closure of an air feeding/exhaustion passage in operation in which a combustion fan is driven.SOLUTION: In operation in which a combustion fan 50 is rotated, presence of air to an exhaustion passage 61 is determined by contrasting a first correction value for correcting a first target rotating speed calculated according to a degree of deviation in load on a combustion fan 50 from a reference level when the combustion fan 50 is so rotated as to reach the first target rotating speed in a high rotating speed range higher than a predetermined rotating speed for determination with a second correction value for correcting a second target rotating speed calculated according to a degree of deviation in load on the combustion fan 50 from the reference level when the combustion fan 50 is so rotated as to reach a second rotating speed in a low rotating speed range equal to or lower than the predetermined rotating speed for determination.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a combustion apparatus. In particular, the present invention relates to a combustion apparatus capable of determining the presence of wind on an exhaust path during operation that rotates a combustion fan.

  2. Description of the Related Art Conventionally, there is known a combustion apparatus that is controlled so that the rotational speed of a combustion fan becomes a target rotational speed that is determined in accordance with the amount of air required for each operation such as a combustion operation. In this type of combustion apparatus, the amount of air in steady state (and hence the load of the combustion fan) in which the rotation speed of the combustion fan is controlled to an arbitrary target rotation speed varies depending on the degree of blockage of the supply / exhaust path. For this reason, there has been proposed a combustion apparatus that corrects the target rotation speed of the combustion fan from the reference target rotation speed when there is no influence of the blockage when the load of the combustion fan decreases due to blockage of the supply / exhaust path.

  In addition, in a combustion apparatus in which an exhaust port for discharging combustion exhaust is open to the outdoors, the wind pressure of outside air may be applied to the exhaust port when there is a wind. When there is wind in such an exhaust path, the amount of exhaust air from the exhaust port decreases as in the case of blockage of the supply and exhaust path, but the load of the combustion fan when there is wind is different from that at the time of blockage. Depending on the air volume and direction of the outside air, it changes greatly in a short time. In particular, in the post-purge operation for discharging the combustion exhaust in the combustion apparatus after the combustion operation, the combustion fan is rotated at a relatively low rotational speed in consideration of energy saving and noise, and therefore, it is easily affected by wind. Even in such a windy state, when the target rotational speed is corrected according to the load of the combustion fan as in the case of blockage, if a gust occurs, the target rotational speed is corrected by a large correction value, and the combustion fan The rotational speed is increased rapidly. Therefore, after the rotation speed is increased, if the air volume and direction of the outside air change in a short time and the wind pressure of the outside air to the exhaust path decreases, the amount of air becomes excessive by rotating the combustion fan at a high rotation speed. Become. As a result, for example, in the combustion operation, there is a problem that the amount of combustion air becomes excessive with respect to the required combustion amount, resulting in poor ignition and misfire. In the post-purge operation, noise is increased and the inside of the combustion device is excessive. There is a problem of being cooled.

  From the above viewpoint, considering the effect of a significant decrease in the load of the combustion fan due to the wind, if the target rotation speed is corrected by the calculated correction value according to the load of the combustion fan during operation, A combustion apparatus that controls a combustion fan so as to gradually approach a target rotational speed whose number is corrected has also been proposed. According to this combustion device, since a certain time lag occurs before reaching the corrected target rotational speed, even if the load on the combustion fan temporarily decreases due to wind, the rapid increase in rotational speed is suppressed. It is done.

  However, the combustion apparatus does not distinguish between the blockage of the supply / exhaust path and the wind to the exhaust path, and when the load of the combustion fan is reduced, the target rotational speed is gradually increased. As a result, the amount of air required for each operation becomes excessive and insufficient, causing problems such as poor ignition and misfiring in the combustion operation. Condensation occurs, and there is a problem that ignition failure is likely to occur in the next combustion operation.

  Also, since the degree of blockage due to aging gradually increases, the conventional combustion device stores the correction value obtained during the current operation, and the target rotational speed at the start of the next operation based on the correction value Is set.

  However, as described above, the conventional combustion apparatus does not discriminate between the blockage of the supply / exhaust path and the wind to the exhaust path. Therefore, when the correction value calculated when the wind is strong is stored, Although the degree of blockage of the air supply / exhaust path is low, the combustion fan is rotated at a high target speed immediately after the start in the next operation. As a result, in the combustion operation, there is a problem that the amount of air at the time of ignition becomes excessive, resulting in an ignition failure or a misfire during the combustion operation. Further, in the post-purge operation, there are problems that noise is increased and the inside of the combustion apparatus is excessively cooled.

JP-A-8-261455 JP 2006-250498 A

  The present invention solves the above-mentioned problems, and the object of the present invention is to clearly discriminate between wind to the exhaust path and blockage of the air supply / exhaust path during the operation of driving the combustion fan, and smooth operation is achieved. It is to provide a viable combustion device.

The present invention
A combustion chamber containing a burner for burning fuel gas;
An air supply path and an exhaust path communicating with the combustion chamber;
A combustion fan for supplying combustion air to the burner;
A fan load detector for detecting the load of the combustion fan;
A target rotational speed determination unit that determines a target rotational speed of the combustion fan based on the correlation between the amount of air when the load of the combustion fan is at a predetermined reference level and the rotational speed of the combustion fan;
A fan control unit for controlling the fan current of the combustion fan so that the combustion fan rotates at a target rotational speed;
A correction value calculating unit for calculating a correction value for correcting the target rotational speed so as to obtain a necessary air amount according to the degree of deviation between the load of the combustion fan and the reference level load detected by the fan load detecting unit; ,
A wind determination unit for determining wind to the exhaust path,
During the operation of rotating the combustion fan, the difference between the load of the combustion fan and the reference level load when the combustion fan is rotated so as to become the first target rotation speed in the high rotation speed region higher than the predetermined determination rotation speed The combustion fan is rotated so that the first correction value for correcting the first target rotational speed calculated according to the degree and the second target rotational speed in a low rotational speed region equal to or lower than a predetermined determination rotational speed are obtained. In comparison with the second correction value for correcting the second target rotational speed calculated according to the degree of deviation between the load of the combustion fan and the reference level load at the time, the presence of wind on the exhaust path is determined It is a combustion apparatus which has the control structure to do.

  The combustion fan load detected by the fan load detector is reduced by both the blockage of the supply / exhaust path and the presence of wind on the exhaust path, so combustion when the combustion fan is rotated at a single target speed It is difficult to distinguish both from the fan load.

  However, if the degree of blockage of the air supply / exhaust path is approximately the same, the ventilation resistance gradually increases as the amount of air increases by increasing the number of revolutions of the combustion fan, so the degree of deviation from the reference level load gradually increases. Become bigger. As a result, in the case of blockage, the correction value for obtaining the necessary air amount is larger in the high rotation speed region than in the low rotation speed region.

  On the other hand, even if wind is generated in the exhaust path, if the amount of air generated by rotating the combustion fan with respect to the amount of outside air is sufficiently large, the load of the combustion fan is reduced. On the other hand, as the rotational speed of the combustion fan decreases, the amount of air decreases, so the load on the combustion fan greatly decreases even if there is a similar amount of wind and wind direction. Therefore, the degree of deviation between the load of the combustion fan and the reference level load in the low rotation speed region is larger than that in the high rotation speed region. As a result, in the case of wind, the correction value for obtaining the required air amount is larger in the low rotation speed region than in the high rotation speed region.

  Therefore, during the operation of rotating the combustion fan, the load of the combustion fan and the load at the reference level when the combustion fan is rotated so as to become the first target rotation speed in the high rotation speed region higher than the predetermined determination rotation speed Combustion fan so that the first correction value for correcting the first target rotation speed calculated according to the degree of deviation from the first rotation speed and the second target rotation speed in a predetermined low rotation speed region equal to or lower than the determination rotation speed By comparing the second correction value for correcting the second target rotation speed calculated according to the degree of deviation between the load when the engine is rotated and the load at the reference level, the wind to the exhaust path is You can determine if it has occurred.

In the above combustion apparatus, preferably,
The operation for driving the combustion fan includes at least one of a pre-purge operation, a combustion operation, and a post-purge operation.

  In the pre-purge operation and the combustion operation, it is possible to prevent poor ignition and misfire by distinguishing between wind and blockage. In addition, by distinguishing between wind and blockage in the post-purge operation, it is possible to prevent excessive cooling in the combustion apparatus while efficiently discharging the combustion exhaust.

In the above combustion apparatus, preferably,
If the first correction value becomes lower than the second correction value during the combustion operation, the minimum post-purge operation speed is increased or the post-purge operation time is extended.

  In the post-purge operation, it is preferable to rotate the combustion fan as low as possible in order to save energy and prevent noise. Therefore, even if the wind pressure of the outside air to the exhaust port is low, the inside of the combustion device is easily completely closed, and the backflow of the combustion exhaust tends to occur. However, according to the combustion apparatus described above, the first correction value and the second correction value are compared during the combustion operation before the post-purge operation, and the first correction value becomes lower than the second correction value. When wind is generated, the minimum post-purge operation speed is increased or the post-purge operation time is extended, so that the exhaust gas can be discharged more efficiently while preventing excessive cooling in the combustion device.

In the above combustion apparatus, preferably,
During the post-purge operation, when the rotation speed of the combustion fan is alternately increased or decreased so that the rotation speed of the combustion fan becomes the first target rotation speed or the second target rotation speed, the first correction value becomes lower than the second correction value. Increase the minimum post-purge operation speed or extend the post-purge operation time.

  According to the combustion apparatus, wind exhaust and blockage can be determined periodically during the post-purge operation, so that the combustion exhaust can be discharged more efficiently.

Preferably, the combustion device further includes:
It has an outside air temperature detection unit that detects outside air temperature,
When the outside air temperature detected by the outside air temperature detecting unit is equal to or lower than a predetermined determination start temperature and the first correction value is lower than the second correction value, the minimum post-purge operation speed is increased or the post-purge operation time Is extended.

  The post-purge operation is performed in order to discharge the combustion exhaust in the combustion device after the combustion operation, but if the backflow of the combustion exhaust occurs due to wind when the outside air temperature is low, the backflowed combustion exhaust will condense. Ignition failure tends to occur during combustion operation. However, according to the combustion apparatus described above, during the post-purge operation, when the outside air temperature becomes equal to or lower than the predetermined determination start temperature and the first correction value becomes lower than the second correction value, the minimum post-purge operation speed is increased. Alternatively, since the post-purge operation time is extended, combustion exhaust can be discharged more efficiently, and ignition failure in the next combustion operation can be prevented.

In the above combustion apparatus, preferably,
If the first correction value is greater than or equal to the second correction value at the end of at least one of the pre-purge operation, the combustion operation, and the post-purge operation, according to the first correction value at the end of each current operation. Correct the target rotation speed at the start of each corresponding operation next time,
When the first correction value becomes lower than the second correction value at the end of at least one of the pre-purge operation, the combustion operation, and the post-purge operation, the first correction value is the second correction value or more. In accordance with the first correction value at the end of each operation, the target rotational speed at the start of each corresponding operation next time is corrected.

  When the first correction value is equal to or greater than the second correction value, there is a high possibility that the load of the combustion fan is reduced due to the blockage of the supply / exhaust path. As described above, in the case of the blockage, the correction value for obtaining the necessary air amount is larger in the high rotation speed region than in the low rotation speed region. Therefore, if the target rotational speed at the start of each corresponding operation is corrected in accordance with the first correction value at the end of each operation, the air supply / exhaust path is shortened within a short time from the start of each operation. The combustion fan can be rotated at a target rotational speed suitable for the degree of blockage.

  On the other hand, when the first correction value is lower than the second correction, there is a high possibility that the load of the combustion fan is reduced due to the wind, and therefore, depending on the first or second correction value at the end of each operation this time. If the target rotational speed at the start of each corresponding operation next time is corrected, the air amount tends to become excessive.

  However, according to the combustion apparatus described above, if the first correction value becomes lower than the second correction during each of the current operations, the next response is made according to the first or second correction value at the end of each current operation. Since the target rotational speed at the start of each operation is not corrected, the target rotational speed is corrected according to the first correction value at the end of the most recent operation when the first correction value is equal to or greater than the second correction value. The combustion fan can be rotated at a target rotational speed suitable for the degree of blockage of the most recent air supply / exhaust path when it is determined that the blockage has occurred in each operation.

In the above combustion apparatus, preferably,
If the first correction value becomes lower than the second correction value during at least one of the pre-purge operation and the combustion operation, the minimum combustion amount in the combustion operation is increased.

  If the first correction value becomes lower than the second correction value during at least one of the pre-purge operation and the combustion operation, there is a high possibility that the load on the combustion fan is reduced due to the wind on the exhaust path. . When the wind pressure of the outside air to the exhaust port increases due to such wind, the pressure in the combustion chamber increases, and the gas pressure of the fuel gas supplied to the burner decreases in a region where the combustion amount is low. Further, in a region where the amount of fuel gas supplied is small and the combustion amount is low, the required amount of combustion air also decreases, so that the combustion fan is rotated at a low target rotational speed. Therefore, misfire tends to occur during the combustion operation due to the wind to the exhaust path. However, according to the combustion apparatus, if the first correction value becomes lower than the second correction value during at least one of the pre-purge operation and the combustion operation, the minimum combustion amount in the combustion operation is increased. As the gas pressure of the fuel gas is increased, the target rotational speed is changed so that the amount of combustion air necessary for the increased minimum combustion amount is obtained. This can prevent misfire during combustion operation in windy conditions.

In the above combustion apparatus, preferably,
When the first correction value becomes lower than the second correction value during the pre-purge operation, the ignition target rotational speed is increased in the combustion operation after the pre-purge operation.

  If the first correction value becomes lower than the second correction value during the pre-purge operation, there is a high possibility that the load of the combustion fan is reduced due to the wind. Therefore, when the burner is ignited in the combustion operation after the pre-purge operation, An air amount smaller than the amount of air required for the burner is supplied to the burner, and ignition failure tends to occur. However, according to the combustion device, during the pre-purge operation, if the first correction value becomes lower than the second correction value, the target rotation speed for ignition is increased, so that it is possible to ensure the amount of air necessary for ignition even in the presence of wind. . Thereby, the ignition failure at the time of a wind can be prevented.

  As described above, according to the present invention, it is possible to determine whether there is wind to the exhaust path and blockage of the supply / exhaust path, and to perform each operation corresponding to the cause of reducing the load of the combustion fan. Thereby, it is possible to prevent ignition failure and misfire in the combustion operation. In the post-purge operation, combustion exhaust can be efficiently discharged while preventing excessive cooling in the combustion apparatus. Therefore, according to the present invention, each operation can be performed smoothly.

FIG. 1 is a schematic diagram showing an example of a combustion apparatus according to an embodiment of the present invention. FIG. 2 is a control block diagram of the control unit of the combustion apparatus according to the embodiment of the present invention. FIG. 3 is a correlation diagram showing the relationship between the rotational speed of the combustion fan and the fan current in the combustion apparatus according to the embodiment of the present invention. FIG. 4 is a part of a flowchart showing an example of the control operation in the pre-purge operation of the combustion apparatus according to the embodiment of the present invention. FIG. 5 is a part of a flowchart showing an example of the control operation in the pre-purge operation of the combustion apparatus according to the embodiment of the present invention. FIG. 6 is a part of a flowchart showing an example of the control operation in the pre-purge operation of the combustion apparatus according to the embodiment of the present invention. FIG. 7 is a part of a flowchart showing an example of the control operation in the combustion operation of the combustion apparatus according to the embodiment of the present invention. FIG. 8 is a part of a flowchart showing an example of the control operation in the combustion operation of the combustion apparatus according to the embodiment of the present invention. FIG. 9 is a part of a flowchart showing an example of the control operation in the combustion operation of the combustion apparatus according to the embodiment of the present invention. FIG. 10 is a part of a flowchart showing an example of the control operation in the post-purge operation of the combustion apparatus according to the embodiment of the present invention. FIG. 11 is a part of a flowchart showing an example of the control operation in the post-purge operation of the combustion apparatus according to the embodiment of the present invention. FIG. 12 is a part of a flowchart showing an example of the control operation in the post-purge operation of the combustion apparatus according to the embodiment of the present invention.

Hereinafter, the combustion apparatus according to the present embodiment will be specifically described with reference to the drawings.
FIG. 1 is a schematic diagram showing an example in which the combustion apparatus of the present embodiment is applied to a water heater. As shown in FIG. 1, the water heater includes a water heater main body 100 and a remote control L disposed in a bathroom, a kitchen, or the like connected to the water heater main body 100. The water heater main body 100 includes a heat exchanger 40, a combustion chamber 10 that houses the gas burner 1, a combustion fan 50 that supplies air to the combustion chamber 10, and a control unit 20 that controls the operation of the water heater. The unit 20 is connected to the remote controller L.

  An air supply path 51 for supplying the air supplied from the combustion fan 50 into the combustion chamber 10 communicates with the lower portion of the combustion chamber 10, and the air in the combustion chamber 10 is connected to the upper portion of the combustion chamber 10. In addition, an exhaust passage 61 for exhausting combustion exhaust from the exhaust port 60 to the outside communicates.

  The combustion fan 50 is connected to a part of the bottom wall of the combustion chamber 10 and is rotated by a motor M. The combustion fan 50 is configured to be able to control the rotation speed (rotational speed) of the combustion fan 50 by controlling the fan current that is the drive current of the motor M.

  Below the water heater main body 100, an outside air temperature thermistor 62 is disposed as an outside air temperature sensor that detects the outside air temperature. Further, a gas supply pipe 7 for supplying fuel gas to the gas burner 1 has an original gas solenoid valve 70, a gas proportional valve 71, and a solenoid valve for controlling supply of fuel gas by a signal from the control unit 20 in order from the upstream side. 72 is arranged. The opening of the gas proportional valve 71 varies in proportion to the energization amount, and the amount of fuel gas supplied to the gas burner 1 is continuously varied. Further, in the water heater main body 100, an ignition electrode 8 for spark discharge to ignite the gas burner 1, an igniter (not shown) for driving the ignition electrode 8, and a flame rod 9 for detecting the combustion flame of the gas burner 1. Etc. are provided.

  The heat exchanger 40 is disposed above the gas burner 1, and a water supply pipe 81 and a hot water discharge pipe 82 are connected to the heat exchanger 40. Although not shown, the water supply pipe 81 is provided with a water amount sensor and a water supply thermistor, and the hot water discharge pipe 82 is provided with a hot water thermistor.

  The control unit 20 is an electronic circuit unit having a CPU, RAM, ROM, interface circuit, and the like. The control unit 20 includes operation data of the remote controller L (data indicating operation on / off operation, data indicating a set value of the target hot water supply temperature, etc.), a water amount sensor, a water supply thermistor, a hot water thermistor, an outside temperature thermistor 62, a frame rod. The detection signal of each sensor such as 9 is input. Further, the combustion fan 50 is provided with a current sensor for detecting the fan current and a rotational speed sensor for detecting the rotational speed of the combustion fan 50, and detection signals from these sensors are also input to the control unit 20.

  The control unit 20 uses these input data to control a combustion system device and a water flow system device of the gas burner 1 by executing a pre-installed program.

  As shown in FIG. 2, the control unit 20 includes a fan current detection unit 21 that detects the fan current of the combustion fan 50, and the combustion fan 50 as main functions realized by an installed program or hardware configuration. A rotation speed detection unit 22 that detects the rotation speed, an outside air temperature detection unit 23 that detects the outside air temperature, and a fan control unit 24 that performs feedback control of the fan current so that the rotation speed of the combustion fan 50 matches the target rotation speed ( (Including a function of a target rotational speed determination unit that determines the target rotational speed of the combustion fan 50 based on the correlation between the amount of air when the load of the combustion fan 50 is at a predetermined reference level and the rotational speed of the combustion fan 50) The correction value for correcting the target rotational speed is calculated in accordance with the load of the combustion fan 50 that varies due to the blockage of the supply / exhaust passages 51, 61 and the wind to the exhaust passage 61. A correction value calculation unit 25 (including a function of a fan load detection unit that detects the load of the combustion fan 50), a rotation speed correction unit 26 that corrects the target rotation speed based on the calculated correction value, and A wind determination unit 27 that determines whether there is wind to the exhaust path 61 and blockage of the supply / exhaust paths 51 and 61 based on the correction value, and a high level that monitors whether the calculated correction value exceeds a predetermined high blockage threshold. A blockage monitoring unit 28, a calorific value calculating unit 29 for calculating the amount of combustion of the gas burner 1 required for hot water supply at a hot water supply set temperature, and an actuator control unit 30 for controlling the operation of the gas proportional valve 71 and the like are provided. ing.

  The fan current detector 21 detects the fan current of the combustion fan 50 based on the detection signal of the current sensor 53 that drives the motor M. The rotation speed detector 22 detects the rotation speed of the combustion fan 50 based on a detection signal of a rotation speed sensor 52 (Hall element or the like) provided in the combustion fan 50. The outside air temperature detection unit detects the temperature of the outside air based on the detection signal from the outside air temperature thermistor 62.

  The fan control unit 24 performs feedback control based on the output of the rotation speed sensor 52 so that the combustion fan 50 rotates at a predetermined pre-purge operation target rotation speed and a post-purge operation target rotation speed in the pre-purge operation and the post-purge operation, respectively. To do. In the combustion operation, the combustion fan 50 is rotated at a predetermined target rotation speed for ignition, and the combustion fan 50 is rotated at the target rotation speed of the combustion fan 50 corresponding to the calculated required combustion amount during hot water supply. In addition, feedback control is performed based on the output of the rotation speed sensor 52. Further, the rotational speed correction unit 26 corrects the target rotational speed of the combustion fan 50 according to the load level of the combustion fan 50 during each operation, and the fan control unit 24 calculates the corrected target rotational speed during each operation. Thus, feedback control is performed based on the output of the rotation speed sensor 52. Note that the fan control unit 24 performs combustion in a state where the target rotational speed in each operation, the supply / exhaust passages 51 and 61 are not blocked (the blockage rate is 0%), and there is no wind to the exhaust passage 61. Data indicating a correlation with a fan current (hereinafter referred to as a reference current) when the fan 50 is rotated at a predetermined target rotation speed (the load of the combustion fan 50 at this time corresponds to a reference level). Pre-stored. Accordingly, the fan control unit 24 also has a function as a target rotation speed determination unit.

  Here, in each of the pre-purge operation, the combustion operation, and the post-purge operation, the fan current when the combustion fan 50 is controlled to a predetermined target rotational speed becomes smaller as the load of the combustion fan 50 decreases. Therefore, the load of the combustion fan 50 can be detected from the magnitude of the fan current when the rotational speed of the combustion fan 50 is controlled to the target rotational speed. Therefore, the fan current detection unit 21 detects the fan current when the fan control unit 24 controls the rotation speed of the combustion fan 50 to the target rotation number, and the correction value calculation unit 25 calculates the current fan current relative to the reference current. A correction value for correcting the target rotational speed is calculated according to the degree of deviation (corresponding to the degree of deviation between the load level of the combustion fan 50 and a predetermined reference level in the present invention).

  The wind presence determination unit 27 performs the first correction when the combustion fan 50 is rotated at the first target rotation speed in the high rotation speed region higher than the predetermined determination rotation speed calculated as described above during each operation. By comparing the value with the second correction value when the combustion fan 50 is rotated at the second target rotation speed in the low rotation speed region equal to or less than the determination rotation speed, the load of the combustion fan 50 is reduced when the exhaust path 61 is reduced. It is determined whether it is caused by wind in the air or due to blockage of the air supply / exhaust paths 51 and 61. Further, when it is determined that wind is generated in the exhaust passage 61, the ignition target rotational speed is corrected and increased if the gas burner 1 is not ignited. Is increased by a predetermined amount. Furthermore, when it is determined that wind is generated in the exhaust path 61 during the post-purge operation, the post-purge operation time is extended by a predetermined time.

  FIG. 3 shows an example for calculating the correction value, and is a graph showing the correlation between the rotational speed of the combustion fan 50 and the fan current in the post-purge operation. In the figure, (i) shows the rotation speed-fan current (reference current) in a state where the supply / exhaust paths 51 and 61 are not blocked (blocking rate is 0%) and there is no wind to the exhaust path 61. (Ii) is a rotational speed-fan current characteristic of a correction value of 1.0 for determining whether to correct the target rotational speed when determining the target rotational speed of the combustion fan 50. This is a reference value line, which is a boundary line in which the air supply / exhaust paths 51 and 61 are slightly blocked or wind is generated in the exhaust path 61 and the load of the combustion fan 50 starts to decrease. In this embodiment, a steady line and a correction reference value line are separately set to prevent hunting. However, the steady line may be used as a reference value line for correction value calculation.

  In the figure, (iii) shows the number of rotations when the load on the combustion fan 50 is reduced due to the wind on the exhaust path 61, although the supply / exhaust paths 51, 61 are not blocked (blockage rate 0%). It is an example of the actual measurement value of the wind line which shows an electric current characteristic, (iv) has the air supply / exhaust path | routes 51 and 61 partially blocked (blocking rate 60%), but the wind direction to the exhaust path | route 61 is It is an example of the actual value of the obstruction | occlusion line which shows the rotation speed-fan electric current characteristic when the load of the combustion fan 50 falls in the state which is not. (V) is an auxiliary value line indicating the rotation speed-fan current characteristic used for calculating the correction value, and is an actual measurement value when the exhaust port 60 is covered and measured in a pseudo completely closed state. . The auxiliary value line uses the rotational speed-fan current characteristic other than the completely blocked state if there is a difference in the degree of divergence between the load level of the combustion fan 50 and the reference level when there is wind and when it is blocked. (For example, an auxiliary value line with a blocking degree of 90%).

In the figure, the rotation speed _NH is the first post-purge operation target rotation speed (for example, 3000 rpm) in the high rotation speed region higher than the determination rotation speed N (for example, 2400 rpm) in the post-purge operation. The number N _L is a second post-purge operation target rotation speed (for example, 1900 rpm) in a low rotation speed region that is equal to or lower than the determination rotation speed N.

In the figure, I _H2 and I _H1 are fan currents in the reference value line and the auxiliary value line when the combustion fan 50 is rotated at the first post-purge operation target rotational speed _NH , respectively, and I _H0 is It is the fan current of the wind line and the blockage line that are actually detected at the same rotational speed. Similarly, I _L2 and I _L1 are fan currents in the reference value line and the auxiliary value line when the combustion fan 50 is rotated at the second post-purge operation target rotation speed N _L , respectively, and I _L0 is the same rotation. It is the fan current of the winded line and the blockage line actually detected by the number. Since only one fan current is detected in actual operation, the fan currents in the winded line and the closed line are indicated by I _H0 and I _L0 in the same notation in the figure.

In the drawing, a _H and b _H are I _H2 -I _H1 and I _H0 -I _H1 when the combustion fan 50 is rotated at the first post-purge operation target rotational speed _NH , respectively, and a _L and b _L are each a _I L2 _{-I L1} and _I L0 _{-I L1} when rotating the combustion fan 50 in the second post-purge operation target rotational speed _{N L.} The correction value calculation unit 25 calculates the first and second correction values R _H and R _L at each rotation speed based on the following equations (1) and (2).
R _H = {(a _H / b _H ) −1} × α + 1 (1)
R _L = {(a _L / b _L ) −1} × β + 1 (2)
In the formula, α and β are constants greater than 0 and less than or equal to 1, respectively.

  As shown in FIG. 3, when the supply / exhaust passages 51, 61 are blocked or a wind is applied to the exhaust passage 61, the fan of the combustion fan 50 at each rotational speed in both the high rotational speed region and the low rotational speed region. The current deviates from the reference current in the direction of decreasing ((iii) and (iv) in FIG. 3). Further, although it depends on the degree of blockage and the degree of wind, the degree of deviation from the reference current is reversed between the high speed region and the low speed region. Therefore, only by detecting the fan current at a single rotational speed, it is determined whether the load reduction of the combustion fan 50 is caused by the blockage of the supply / exhaust passages 51 and 61 or the wind to the exhaust passage 61. Difficult to do.

  However, the rate of change of the fan current with respect to the rotation speed during wind is larger than that in the blockage. This is because if the degree of blockage of the air supply / exhaust paths 51 and 61 is approximately the same, the ventilation resistance gradually increases as the amount of air increases as the number of revolutions of the combustion fan 50 is increased. This is because the degree gradually increases. As a result, in the case of blockage, the correction value for correcting the target rotational speed in order to obtain the necessary air amount is larger in the high rotational speed region than in the low rotational speed region.

  On the other hand, when the wind pressure of the outside air is generated at the exhaust port 60 when there is a wind, the load on the combustion fan 50 is reduced if the amount of air by rotating the combustion fan 50 with respect to the volume of the outside air is sufficiently large. Is small, the degree of deviation from the reference current is small. On the other hand, as the rotational speed of the combustion fan 50 decreases, the amount of air decreases. Therefore, even if the outside air pressure to the exhaust port 60 is low, the combustion fan 50 is significantly blocked and the load on the combustion fan 50 is significantly reduced. As a result, in the case of wind, the lower the rotational speed of the combustion fan 50, the greater the degree of deviation from the reference current. Therefore, the correction value for correcting the target rotational speed in order to obtain the required amount of air is a high rotational speed. The low rotational speed region becomes larger than the region. In particular, in the post-purge operation, the combustion fan 50 is rotated at a relatively low rotational speed in consideration of energy saving and noise, so that it is likely to be in a completely closed state as shown in FIG.

Therefore, the difference between the load of the combustion fan 50 and the reference level load when the combustion fan 50 is rotated so as to be the first post-purge operation target rotation speed in the high rotation speed region higher than the predetermined determination rotation speed. Combustion fan 50 when combustion fan 50 is rotated so as to have a first correction value _RH calculated according to the degree and a second post-purge operation target rotational speed in a low rotational speed region equal to or lower than the rotational speed for determination. Whether the reduction in the load of the combustion fan 50 is caused by wind on the exhaust passage 61 by comparing the second correction value _RL calculated according to the degree of deviation between the load at the reference level and the load at the reference level Alternatively, it can be determined whether it is caused by blockage of the air supply / exhaust paths 51 and 61. Although FIG. 3 shows the correlation between the rotational speed of the combustion fan 50 and the fan current in the post-purge operation, the presence of wind is similarly determined in the pre-purge operation and the combustion operation. However, since the range of the rotational speed used varies depending on the amount of air required for each operation, the determination rotational speed and the first and second target rotational speeds are set to the rotational speed corresponding to each operation. The

  In addition, the calorific value calculation unit 29 is configured so that the hot water temperature detected by the hot water thermistor 85 is based on the water supply temperature detected by the water supply thermistor 84 and the water supply amount detected by the water amount sensor 83 during the combustion operation. Calculate the required amount of combustion. The control unit 20 performs so-called fan-preceding combustion control that controls the energization amount of the gas proportional valve 71 in accordance with the actual rotational speed of the combustion fan 50 during the combustion operation. Therefore, when the target rotation number is corrected, the actuator control unit 30 divides the rotation number detected by the rotation number detection unit 22 by the correction value to cancel the correction amount of the target rotation number. Then, the energization amount of the gas proportional valve 71 is controlled in accordance with the rotational speed in which the correction amount is canceled in this way.

Next, details of the control operation in the water heater of the present embodiment will be described with reference to the flowcharts of FIGS.
As shown in FIG. 4, when a user opens a hot water supply terminal such as a hot water tap in a state where power is supplied to the water heater, the water flow amount W flowing through the water supply pipe 81 is a predetermined working water amount (for example, It is determined based on the detection signal of the water amount sensor 83 whether or not (2.7 liters / minute) or more (step ST1).

  Then, when water flow exceeding the amount of working water is detected, the control unit 20 starts the pre-purge operation. First, it is determined whether or not the flag F1 is set to “1” (step ST2).

When the flag F1 is not “1”, the process proceeds to step ST3, and when the flag F1 is “1”, the process proceeds to step ST7. During the previous pre-purge operation, the flag F1 is determined to be blocked by a wind determination described later, and both the first and second correction values R _H and R _L are less than 1.1 (for example, the blocking degree is 60%). Or in the previous pre-purge operation, it is determined that there is a wind by the wind determination, and both the first and second correction values R _H and R _L in the past operation up to that point are 1.1. Set to “0” when there is no occlusion history. In addition, when the flag F1 is the first operation after turning on the power supply of the water heater, during the previous pre-purge operation, it is determined that the wind is determined to be blocked, and any of the first or second correction values R _H and R _L Is 1.1 or more (for example, the degree of blockage is 60% or more), or during the previous pre-purge operation, it was determined that there was a wind in the wind determination, but the first or second correction in the past operation If there is a blockage history in which one of the values R _H and R _L is 1.1 or more, it is set to “1” (steps ST129 to ST135).

When the flag F1 is not “1”, since the blockage of the air supply / exhaust paths 51 and 61 has not been confirmed in the previous pre-purge operation, the combustion fan 50 is rotated at a predetermined first pre-purge operation target rotational speed (for example, 3300 rpm). (Step ST3). Then, the control unit 20 measures a predetermined time (for example, 1 second) corresponding to the update cycle of the first correction value _RH described later in the correction of the target rotation speed and the wind determination in the next steps ST5 and ST6. Timer Tm is started (step ST4). At this time, since the flag F1 is not “1”, the first pre-purge operation target rotational speed supplies the air amount necessary for performing the predetermined pre-purge operation when the load of the combustion fan 50 is a reference level load. The number of revolutions that can be determined, and is determined based on reference data created in advance based on the correlation between the number of revolutions and the fan current. On the other hand, when the flag F1 is “1” and the correction value in the previous pre-purge operation is not stored in the initial operation, the first pre-purge operation target is based on a predetermined initial correction value (for example, 1.0). If the rotation speed is corrected and the blockage of the air supply / exhaust paths 51 and 61 is determined during the previous or previous pre-purge operation, the first pre-purge operation target rotation speed is corrected according to the first correction value _RH. (Step ST7). In addition, even if the target rotational speed determined at the start of each operation is different, the correction operation of the target rotational speed and the control operation for determining the presence of wind including the combustion operation and the post purge operation are the same. The case where the flag F is set to “0” in each operation will be described, and the description of the overlapping parts when the flag F is set to “1” will be omitted.

The correction of the target rotation speed in the pre-purge operation determines the current target rotation speed by correcting the determined target rotation speed in accordance with the current value of the correction value that is sequentially updated in the wind determination. Specifically, during the current pre-purge operation, when the first and second correction values R _H and R _L are updated in the wind determination, the updated first and second correction values R _H and R _L are The target rotational speed is corrected by using (step ST5).

In the wind presence determination in the pre-purge operation, the first pre-purge operation target rotational speed in the high rotational speed region higher than the predetermined rotational speed for determination (for example, 2400 rpm) for the combustion fan 50 for a predetermined first measurement time t _H (for example, 10 seconds). And the combustion fan 50 is rotated at the second pre-purge operation target rotational speed (for example, 1500 rpm) in the low rotational speed region equal to or lower than the rotational speed for determination for the second measurement time t _L (for example, 10 seconds). The second determination is performed at least once each (step ST6). Note that the first and second determinations may be performed alternately a plurality of times.

FIG. 5 and FIG. 6 are flowcharts of a subroutine for correcting the target rotational speed and determining the presence of wind in the pre-purge operation, and are predetermined when the combustion fan 50 is rotating in the high rotational speed region until the timer Tm expires. The fan current is acquired at every sampling time (for example, 20 mS) and stored. Then, when the timer Tm expires, the average value of the sampled current fan current is calculated, and combustion is performed at the first pre-purge operation target rotational speed by the calculation formula of the first correction value _RH of the formula (1) described above. The current first correction value R _HP is calculated according to the degree of deviation between the current fan current when the fan 50 is rotating and the fan current of the reference value line (steps ST101 to ST104).

At this time, when the current first correction value R _HP changes by more than a predetermined change amount ΔR _H (for example, ± 0.005) from the stored first correction value _RH , the first correction value after the change The first correction value _RH is increased or decreased so as to reach R _HP , and the first correction value _RH is updated. Therefore, the first correction value R _H that varies per unit time is multiplied by the target rotational speed, the target speed becomes a state of being corrected by the first correction value R _H after a predetermined time. As a result, even if the current first correction value R _HP changes greatly due to wind, a sudden change in the target rotational speed does not occur. When the first correction value _RH is updated, a new timer Tm is started (steps ST105 to ST109). In the present embodiment, as will be described later, the case where the current first correction value R _HP in the current pre-purge operation is increased due to a decrease in the load of the combustion fan 50 caused by wind is also considered. Until the current wind determination is completed, the most recent first correction value _RH when it is determined as a blockage in the wind determination in the previous pre-purge operation is held.

When the predetermined first measurement time t _H elapses, the rotation speed of the combustion fan 50 is decreased to the second pre-purge operation rotation speed in the low rotation speed region for the predetermined second measurement time t _L (step ST111), and the first correction is performed. Similar to the value _RH , every sampling time (for example, 20 mS) when the combustion fan 50 is rotating in the low speed range until the predetermined timer Tm is timed up (for example, 0.02 seconds). The fan current is acquired and stored. Thus, by setting the update of the second correction value _RL in the low rotation speed region in a shorter time than the first correction value _RH, it is possible to determine the presence of wind earlier. When the timer Tm expires, the average value of the sampled current fan current is calculated, and combustion is performed at the second pre-purge operation target rotational speed according to the calculation formula of the second correction value _RL of the formula (2) described above. The current second correction value R _LP corresponding to the degree of deviation between the current fan current when the fan 50 is rotating and the fan current of the reference value line is calculated (steps ST121 to ST124).

Next, when the current second correction value R _LP changes from the stored second correction value R _L by a predetermined change amount ΔR _L (for example, ± 0.005) or more, the changed second correction value R The second correction value _RL is increased or decreased so as to reach _LP , the second correction value _RL is updated, the updated second correction value _RL is multiplied by the target rotation speed, and the target rotation is reached after a predetermined time. The number is corrected by the second correction value _RL (steps ST125 to ST128). Note that the second correction value _RL is also the latest second correction value _RL in the past closing history until the current wind determination is completed.

Until the second measurement time t _L has elapsed, a second correction value R _L and the updated first correction value R _H, which is updated is compared. Then, if the first correction value _{R H} of the pre-purge operation at the end that the second measuring time _{t L} has elapsed second correction value _{R L} or more (in step ST129, No), the combustion fan 50 load and the reference level Since the degree of deviation from the load is larger in the high engine speed region than in the low engine speed region, it can be determined that the load on the combustion fan 50 is reduced due to the blockage of the supply / exhaust paths 51 and 61. At this time, if either of the first or second correction values R _H and R _L is 1.1 or more, it can be determined that the degree of blockage of the air supply / exhaust paths 51 and 61 is increased to some extent. Therefore, the flag F1 is set to “1” (steps ST131 to ST132 and ST135). If the first correction value _RH is equal to or greater than the second correction value _RL , but both the first and second correction values _RH and _RL are less than 1.1 (No in step ST131), It can be determined that the degree of blockage of the air supply / exhaust paths 51 and 61 is small. For this reason, the flag F1 is set to “0” (step ST134).

On the other hand, if the second correction value _RL is larger than the first correction value _RH (Yes in step ST129), the degree of deviation between the load of the combustion fan 50 and the reference level load is high in the low rotation speed region. Since it is larger than several regions, it can be determined that the load of the combustion fan 50 is reduced due to the wind to the exhaust passage 61 during the pre-purge operation (step ST130). Further, if the target rotational speed at the start of the next pre-purge operation is corrected using the first or second correction values R _H and R _L when it is determined that there is a wind, the supply / exhaust path 51, Although the degree of blockage 61 is originally low, the amount of air becomes excessive. For this reason, the first correction value _RH is equal to or greater than the second correction value _RL in the previous wind determination of pre-purge operation, and one of the first or second correction values _RH and _{RL is} equal to or greater than 1.1. It is further determined whether or not there is an occlusion history determined as the occlusion degree (step ST133). If there is a blockage history in the past pre-purge operation, the flag F1 is set to “1” (step ST135). Although not shown, in this case, this first and second correction value R _H is updated in pre-purge _operation, the R _L, and obstruction the determined last of the first and second correction value R _H, R _L Update to Therefore, when it is determined that there is a wind in the current wind determination in the pre-purge operation, the first and second correction values R _H and R _L are not stored. If it is determined that there is a wind and there is no blockage history, the flag F1 is set to “0” (step ST134).

When the wind presence determination ends, it is determined whether or not the updated first correction value _RH is equal to or greater than a predetermined blockage threshold (for example, 1.2 or greater). When it is determined that the air supply / exhaust passages 51 and 61 are closed so that the required amount of combustion air cannot be secured, the combustion fan 50 is stopped without shifting to the combustion operation, and a speaker or the like (not shown) Is notified of abnormality (steps ST11 to ST13).

Further, in the presence of wind, when it is determined that the load of the combustion fan 50 is reduced due to the wind to the exhaust passage 61, the pre-purge operation is performed because the air amount is temporarily insufficient due to a gust of wind. If the combustion fan 50 is rotated at the target rotation speed for ignition corresponding to the load at the reference level in the combustion operation that is subsequently performed, the amount of air is insufficient. For this reason, the combustion fan 50 is rotated at the ignition target rotation speed that is corrected based on the first correction value _RH used at the end of the wind determination. Thereby, the air quantity required at the time of ignition can be ensured, and the gas burner 1 can be reliably ignited. On the other hand, if it is determined in the wind determination that the load of the combustion fan 50 is reduced due to the blockage of the supply / exhaust passages 51, 61, the combustion fan 50 is rotated at a predetermined target rotation speed for ignition ( Steps ST14 to ST16). Note that, even when it is determined to be blocked, the ignition target rotational speed may be corrected using the correction value calculated in the presence of wind determination.

  The correction of the target rotation speed and the determination of the presence of wind have been described for the case where the flag F1 is set to “0”. However, when the flag F1 is set to “1”, as described above, the pre-purge operation is performed. Except for rotating the combustion fan at the first pre-purge operation target rotational speed corrected with the previous correction value at the start, the target rotational speed correction and wind presence determination are similarly performed (steps ST7 to ST10). As a result, it is possible to determine the presence of wind more accurately while ensuring the amount of air necessary for the pre-purge operation.

  When the pre-purge operation is finished, the control unit 20 executes an ignition process shown in FIG. 7 (step ST21). In this ignition process, with the combustion fan 50 rotated at the ignition target rotational speed or the corrected target rotational speed as described above, the igniter is operated to cause a spark discharge in the ignition electrode 8, and The original gas solenoid valve 70 and the solenoid valve 72 are opened, and the gas proportional valve 71 is operated to the ignition opening. Thereby, the fuel gas is supplied to the gas burner 1 while the combustion fan 50 and the ignition electrode 8 are in operation, and the gas burner 1 is ignited.

  When the ignition of the gas burner 1 is detected by the detection signal of the frame rod 9, the operation of the igniter is stopped. Next, similarly to the pre-purge operation, the control unit 20 determines whether or not the flag F2 is set to “1” (step ST22). When the flag F2 is not “1”, the process proceeds to step ST23, and when the flag F2 is “1”, the process proceeds to step ST31. As shown in FIG. 9, the flag F2 is set based on wind and blockage in the wind determination of the previous combustion operation as in the pre-purge operation (steps ST233 and ST234).

The control unit 20 then counts a predetermined time (for example, 1 second) corresponding to the update period of the first correction value _RH in the correction of the target rotational speed and the wind determination in the next steps ST25 and ST26. Is started (step ST23). Next, the combustion amount of the gas burner 1 is controlled by controlling the rotational speed of the combustion fan 50 and the amount of fuel gas supplied to the gas burner 1 (step ST24).

  Specifically, the calorific value calculation unit 29 calculates the required combustion amount at which the hot water temperature detected by the hot water thermistor 85 becomes the set temperature based on the detected temperature of the water supply thermistor 84 and the detected water amount of the water amount sensor 83. Then, the control unit 20 determines a combustion target rotation speed of the combustion fan 50 for supplying combustion air in an amount corresponding to the required combustion amount, and preset combustion corresponding to the calculated required combustion amount. The fan control unit 24 performs feedback control on the combustion fan 50 based on the rotational speed detected by the rotational speed detection unit 22 so that the combustion fan 50 rotates at the target rotational speed (step ST24).

  As described above, the target rotational speed for combustion is the rotational speed at which combustion air corresponding to the combustion amount of the gas burner 1 can be supplied to the gas burner 1 when the load of the combustion fan 50 is a reference level load. In this case, since the flag F2 is not “1”, the flag F2 is determined based on the correlation between the combustion amount of the gas burner 1 at the reference level load and the rotational speed of the combustion fan 50.

  Next, when the proportional control is being executed, the correction of the target rotation speed and the determination of the presence of wind are executed as in the pre-purge operation (steps ST25 to ST26).

FIGS. 8 and 9 are flowcharts of a subroutine for correcting the target rotational speed and determining whether there is wind in the combustion operation. Since the control operation in the correction of the target rotational speed is the same as that in the pre-purge operation, a detailed description is omitted, but the target rotational speed of the combustion fan 50 is set according to the required combustion amount during the combustion operation. The target rotational speed cannot be arbitrarily changed in the wind determination. Therefore, in the wind determination during the combustion operation, the first combustion in the high rotation speed region in which the target rotation speed at the reference level set according to the required combustion amount is higher than a predetermined determination rotation speed (for example, 2400 rpm). And detecting and storing the fan current of the combustion fan 50 when the second target rotation speed (for example, 1500 rpm) in the low rotation speed region equal to or less than the determination rotation speed is obtained. Then, the first and second correction values R _H and R _L are calculated and updated. Then, by comparing the updated first and second correction values R _H and R _L , wind and blockage are determined. Similarly to the pre-purge operation, the flag F2 is set based on the determination of wind and blockage and the blockage history (steps ST201 to ST235).

  Further, when it is determined that the blockage is high during the combustion operation, the amount of air necessary for combustion cannot be ensured, and incomplete combustion may occur. Therefore, the combustion fan 50 is stopped, the original gas solenoid valve 70, the gas The proportional valve 71 and the electromagnetic valve 72 are closed, and an abnormality is notified from a speaker or the like (steps ST27 and ST36 to ST37).

  Further, when it is determined that there is a wind during the combustion operation, the wind pressure of the outside air to the exhaust port 60 is increased, so that the pressure in the combustion chamber 10 becomes high, and the gas burner 1 is turned on in the region where the combustion amount is low. Not only the gas pressure of the supplied fuel gas is lowered, but also the required combustion air is reduced, so that the gas burner 1 tends to misfire. For this reason, the minimum combustion amount is increased by a predetermined amount (for example, 10%) (step ST29). Thereby, even when the gas burner 1 is combusted in the range of the low combustion amount, even if the air amount is reduced due to the wind, the combustion failure and misfire of the gas burner 1 can be prevented. Even when the flag F2 is set to “1”, the target rotational speed is corrected so that the amount of combustion air necessary for combustion can be obtained based on the correction value in the previous combustion operation at the start of the combustion operation. Except for the above, the correction of the target rotational speed and the determination of the presence of wind are performed in the same manner (steps ST31 to ST35 and ST38 to ST39).

  When the user closes the hot water tap or the like and the water flow amount W flowing through the water supply pipe 81 becomes less than a predetermined flow rate (for example, 2.7 liters / minute), the original gas solenoid valve 70 is closed and the gas burner 1 is extinguished. Then, the control unit 20 performs the post purge operation shown in FIG.

  In the post-purge operation, first, it is determined whether or not the outside air temperature detected by the outside air temperature detector 23 is equal to or lower than a predetermined determination start temperature (for example, 0 ° C.) at which condensation is likely to occur. If the outside air temperature is higher than the determination start temperature, it is difficult for condensation to occur even if a backflow of the combustion exhaust occurs due to the wind. It is rotated at the minimum rotation speed (for example, 900 rpm) (steps ST51 and ST73 to ST74).

  When the outside air temperature becomes equal to or lower than the determination start temperature, it is determined whether the flag F3 is set to “1” as in the pre-purge operation (step ST52). When the flag F3 is not “1”, the process proceeds to step ST53, and when the flag F3 is “1”, the process proceeds to step ST62. As shown in FIG. 12, the flag F3 is set based on the wind and blockage in the wind determination of the previous post-purge operation as in the pre-purge operation (steps ST333 and ST334).

When the flag F3 is not “1”, since the blockage of the air supply / exhaust paths 51 and 61 has not been confirmed in the previous post purge operation, the combustion fan 50 is turned on at a predetermined first post purge operation target rotational speed (for example, 3000 rpm). Rotate (step ST53). The control unit 20 then counts a predetermined time (for example, 1 second) corresponding to the update period of the first correction value _RH in the correction of the target rotational speed and the wind determination in the next steps ST55 and ST56. Is started (step ST54). At this time, since the flag F3 is not “1”, the first post-purge operation target rotational speed supplies the air amount necessary for a predetermined post-purge operation when the load of the combustion fan 50 is a reference level load. The number of rotations is determined based on reference data created in advance based on the correlation between the number of rotations and the fan current.

  Next, similarly to the pre-purge operation, correction of the target rotation speed and wind determination are executed (steps ST55 to ST56).

FIGS. 11 and 12 are flowcharts of a subroutine for correcting the target rotational speed and determining whether there is wind in the post-purge operation. Since the control operation in the correction of the target rotational speed is the same as that of the pre-purge operation, a detailed description thereof will be omitted, but in this post-purge operation, the first measurement time t _H (for example, 10 seconds) and the first The first determination for rotating the combustion fan 50 at the post-purge operation target rotational speed, the combustion fan 50 at the predetermined second measurement time t _L (for example, 2 minutes), and the second post-purge operation target rotational speed (for example, 1900 rpm). The second determination to rotate is performed alternately until a predetermined post purge operation time elapses. In each determination, the fan current of the combustion fan 50 is detected and stored, and the first and second correction values R _H and R _L are calculated and updated. Further, the wind and the blockage are determined by comparing the updated first and second correction values R _H and R _L. Further, similarly to the pre-purge operation, the flag F3 is set based on the determination of wind and blockage and the blockage history (steps ST301 to ST337).

  In the post-purge operation, when it is determined that the air supply / exhaust passages 51 and 61 are closed so that a sufficient amount of air cannot be secured, the combustion fan 50 is stopped and an abnormality is notified from a speaker or the like (not shown). (Steps ST57 and ST67 to ST68).

  Further, in the presence of wind, when it is determined that the load of the combustion fan 50 is reduced due to the wind to the exhaust passage 61, the air temperature is temporarily insufficient due to the gust of wind. If the combustion exhaust gas is low, dew condensation occurs when the combustion exhaust gas flows backward, and ignition failure may occur in the next combustion operation. For this reason, the set post purge operation time is extended by a predetermined time (for example, 1 minute) (steps ST58 to ST59). Thereby, even when a backflow of combustion exhaust occurs due to a temporary gust, the combustion exhaust can be discharged. In the present embodiment, during the post-purge operation, the rotational speed of the combustion fan 50 is alternately increased / decreased at the first and second post-purge operation target rotational speeds. May be used as the first and second post-purge operation target rotation speeds, and the combustion fan 50 may be rotated at the minimum post-purge operation rotation speed except for the determination of wind. In this case, when it is determined that there is a wind, the minimum post-purge operation speed may be increased by a predetermined speed, the post-purge operation time may be extended, and the post-purge operation minimum speed may be increased. . Even when the flag F3 is set to “1”, the target rotational speed is corrected so that the necessary air amount can be obtained based on the correction value in the previous post-purge operation at the start of the post-purge operation. Similarly, the correction of the target rotational speed and the determination of wind are executed (steps ST63 to ST66 and ST69 to ST72).

(Other embodiments)
(1) In the above embodiment, a water heater using a gas burner is shown as the combustion apparatus of the present invention. However, the combustion apparatus forcibly supplies combustion air to the combustion chamber in which the burner is accommodated by a combustion fan. If so, the present invention can also be applied to other types of combustion devices such as warm air heaters.
(2) In the above embodiment, whether to extend the post-purge operation time in the post-purge operation is determined based on the presence of wind during the post-purge operation. You may perform based on a wind determination.

DESCRIPTION OF SYMBOLS 1 Gas burner 10 Combustion chamber 20 Control unit 21 Fan current detection part 22 Rotation speed detection part 23 Outside air temperature detection part 24 Fan control part 25 Correction value calculation part 30 Winding determination part 50 Combustion fan 51 Supply path 60 Exhaust port 61 Exhaust path

Claims (8)

A combustion chamber containing a burner for burning fuel gas;
An air supply path and an exhaust path communicating with the combustion chamber;
A combustion fan for supplying combustion air to the burner;
A fan load detector for detecting the load of the combustion fan;
A target rotational speed determination unit that determines a target rotational speed of the combustion fan based on the correlation between the amount of air when the load of the combustion fan is at a predetermined reference level and the rotational speed of the combustion fan;
A fan control unit for controlling the fan current of the combustion fan so that the combustion fan rotates at a target rotational speed;
A correction value calculating unit for calculating a correction value for correcting the target rotational speed so as to obtain a necessary air amount according to the degree of deviation between the load of the combustion fan and the reference level load detected by the fan load detecting unit; ,
A wind determination unit for determining wind to the exhaust path,
During the operation of rotating the combustion fan, the difference between the load of the combustion fan and the reference level load when the combustion fan is rotated so as to become the first target rotation speed in the high rotation speed region higher than the predetermined determination rotation speed The combustion fan is rotated so that the first correction value for correcting the first target rotational speed calculated according to the degree and the second target rotational speed in a low rotational speed region equal to or lower than a predetermined determination rotational speed are obtained. In comparison with the second correction value for correcting the second target rotational speed calculated according to the degree of deviation between the load of the combustion fan and the reference level load at the time, the presence of wind on the exhaust path is determined Combustion device having a control configuration. The combustion apparatus according to claim 1, wherein
An operation for rotating the combustion fan is at least one of a pre-purge operation, a combustion operation, and a post-purge operation. The combustion apparatus according to claim 2, wherein
When the first correction value becomes lower than the second correction value during the combustion operation, the combustion apparatus increases the post-purge operation minimum speed or extends the post-purge operation time in the post-purge operation after the combustion operation. The combustion apparatus according to claim 2 or 3,
During the post-purge operation, when the rotation speed of the combustion fan is alternately increased or decreased so that the rotation speed of the combustion fan becomes the first target rotation speed or the second target rotation speed, the first correction value becomes lower than the second correction value. A combustion device that increases the minimum post-purge operation speed or extends the post-purge operation time. The combustion apparatus according to any one of claims 2 to 4, further comprising:
It has an outside air temperature detector that detects the outside air temperature,
When the outside air temperature detected by the outside air temperature detecting unit is equal to or lower than a predetermined determination start temperature and the first correction value is lower than the second correction value, the minimum post-purge operation speed is increased or the post-purge operation time Extend the combustion device. The combustion apparatus according to any one of claims 2 to 5,
If the first correction value is greater than or equal to the second correction value at the end of at least one of the pre-purge operation, the combustion operation, and the post-purge operation, according to the first correction value at the end of each current operation. Correct the target rotation speed at the start of each corresponding operation next time,
When the first correction value becomes lower than the second correction value at the end of at least one of the pre-purge operation, the combustion operation, and the post-purge operation, the first correction value is the second correction value or more. A combustion apparatus that corrects the target rotational speed at the start of each corresponding operation next time according to the first correction value at the end of each operation. The combustion apparatus according to any one of claims 2 to 6,
A combustion apparatus that increases the minimum combustion amount in the combustion operation when the first correction value becomes lower than the second correction value during at least one of the pre-purge operation and the combustion operation. The combustion apparatus according to any one of claims 2 to 7,
A combustion apparatus that increases the target rotational speed for ignition in the combustion operation after the completion of the pre-purge operation when the first correction value becomes lower than the second correction value during the pre-purge operation.

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