JP2012037070A - Combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion device which highly precisely sets a target rotation speed of a fan while responding to a change in the lapse of time of the degree of closure of a suction and exhaust passage and, at the same time, determines the target rotation speed of the fan while responding to a sudden or temporary change of the degree of closure of the suction and exhaust passage, too.SOLUTION: When a combustion operation continues for a prescribed time or more, the fan is operated at a prescribed closure detecting rotation speed upon the stopping of the combustion operation, a first correction coefficient Ha is calculated from the relation between a fan current and the closure detecting rotation speed upon the operation of the fan and, after upper limit correction, the first correction coefficient Ha is stored in a memory 11 as the fourth correction coefficient Ha. Along with the start of the combustion operation, the controlling of the fan is started at the target rotation speed calculated by setting the initial value of H to be Ha, a fan current Id is detected and the second correction coefficient Hb is calculated from Id (STEP5, 9, 10). Ha is compared with Hb and, in case of Hb-Ha<a positive given value C1 (STEP11NO), the target rotation speed is changed into the target rotation speed re-calculated by replacing H to Hb to control the fan.

Description

  The present invention relates to a combustion apparatus including a fan for forcibly supplying and exhausting a burner.

  2. Description of the Related Art Conventionally, a combustion apparatus that controls the rotational speed of a fan so as to perform supply / exhaust according to the burner combustion amount is known. In such a combustion apparatus, if the supply / exhaust passage where the supply / exhaust is performed by the fan is blocked, the flow rate of the combustion air supplied to the burner may decrease, and the combustion state of the burner may deteriorate.

  Therefore, the degree of blockage of the air supply / exhaust passage is detected, and correction is performed to increase the rotation speed of the fan as the degree of blockage of the air supply / exhaust passage increases. 2. Description of the Related Art Combustion devices are known that do not cause a shortage of combustion air supply. As a method of detecting the degree of blockage in such a combustion apparatus, a method of grasping the degree of blockage from a change in fan driving current (hereinafter referred to as fan current) necessary for operating the fan at a predetermined rotational speed is generally used. Is.

  However, in a combustion device in which the current supplied to the fan during combustion is relatively small, even if the air flow of the fan decreases due to blockage of the supply / exhaust passage, the decrease in the fan current associated therewith is extremely small. It is difficult to distinguish between the case where the fan current decreases due to the ambient temperature change and the case where the fan current decreases due to blockage, and it is difficult to detect the blockage degree of the supply / exhaust passage based on the fan current during combustion. is there.

  Therefore, the degree of blockage of the supply / exhaust passage due to the fan current is detected by rotating the fan at a predetermined blockage detection rotation speed at a high speed when the burner burns for a predetermined time or more and the fire is extinguished and the ambient temperature is stable. A combustion apparatus has been proposed in which the current is increased (see, for example, Patent Document 1).

  In the combustion apparatus described in Patent Literature 1, the blockage correction coefficient indicating the blockage degree of the supply / exhaust passage is accurately calculated by operating the fan at the blockage detection rotation speed after extinguishing the burner in this way. . Then, the calculated blockage correction value is held in the storage means, and at the next combustion operation of the burner, the detected rotational speed of the fan is set to the burner combustion amount and the blockage correction value held in the storage device. The fan current is controlled so that the target rotational speed determined based on the target rotational speed is obtained.

JP 2003-161439 A

  The combustion apparatus of Patent Document 1 performs correction value calculation after stopping the combustion operation only when the combustion operation before the combustion operation is stopped for a predetermined duration or longer and by increasing the fan current. There is an advantage that the blockage correction value can be obtained with high accuracy. However, the target rotational speed of the fan during the combustion operation is based on the blockage correction value calculated at the end of the past combustion operation. For this reason, although the gradual change in the degree of blockage of the supply / exhaust passage according to the use of the combustion device, that is, the change in the degree of blockage over time can be accurately handled, If the degree of blockage of the supply / exhaust passage changes suddenly or temporarily before the start, there is a disadvantage that the target rotational speed cannot be set accurately according to the degree of blockage.

  An object of the present invention is to set the target rotational speed of the fan with high accuracy in response to a change in the degree of blockage of the supply / exhaust passage with time, and to suddenly or temporarily change the degree of blockage of the supply / exhaust passage. The combustion apparatus which can determine the target rotational speed of a fan corresponding also effectively is provided.

In the first invention, the combustion device comprises:
A combustion chamber containing a burner;
A fan that is provided in a supply / exhaust passage communicating with the combustion chamber and that supplies combustion air to the burner and exhausts combustion exhaust gas from the burner;
A rotational speed sensor for detecting the rotational speed of the fan;
A fan current sensor for detecting a fan current supplied to the fan;
Fan control means for controlling the fan current so that the target rotational speed of the fan becomes a target rotational speed corresponding to the amount of combustion of the burner during the combustion operation of the burner;
After the burner combustion operation has continued for a predetermined time or longer, after the burner has stopped burning, the fan is operated at a predetermined blockage detection rotation speed, and is operated at the blockage detection rotation speed and the blockage detection rotation speed. A blockage correction value calculating means for maintaining and updating the fourth blockage correction value held in the storage means by the first blockage correction value indicating the blockage degree of the supply / exhaust passage from the relationship with the fan current at the time;
During the combustion operation of the burner, a second blockage correction value indicating the blockage degree of the supply / exhaust passage is calculated from the relationship between the rotation speed of the fan and the fan current, and the increase of the blockage degree of the supply / exhaust passage is increased. When the difference between the fourth blockage correction value and the second blockage correction value indicates that the level is equal to or lower than the first level, the target rotation is based on the burner combustion amount and the fourth blockage correction value. When the speed is determined and the difference between the fourth blockage correction value and the second blockage correction value indicates that the increase in the blockage degree of the supply / exhaust passage is greater than the first level, the combustion amount of the burner And a target rotational speed determining means for determining the target rotational speed based on the second closing correction value.

  According to the first invention, the target rotational speed determination means calculates the second blockage correction value indicating the blockage degree of the supply / exhaust passage from the relationship between the rotational speed of the fan and the fan current during the burner combustion operation, When the difference between the fourth blockage correction value and the second blockage correction value indicates that the increase in the blockage degree of the supply / exhaust passage is below the first level, the burner combustion amount and the first blockage correction value are Based on this, the target rotational speed is determined. Therefore, when there is no sudden or temporary increase in the degree of blockage of the supply / exhaust passage, the second blockage correction value is corrected from the fourth blockage correction value to the possibility of deterioration of combustion due to the subsequent temporary blockage. It is possible to determine the target rotational speed with high accuracy corresponding to the blockage over time for the supply / exhaust passage based on the fourth blockage correction value while leaving room for changing to the value. When the difference between the fourth blockage correction value and the second blockage correction value indicates that the increase in the blockage degree of the supply / exhaust passage is greater than the first level, the burner combustion amount and the second blockage correction value are Based on this, the target rotational speed is determined. That is, when the difference between the fourth blockage correction value and the second blockage correction value indicates that the increase in the blockage degree of the supply / exhaust passage is equal to or higher than the first level, Since the influence due to the possibility of sudden blockage is higher, the target rotational speed can be accurately determined so as to deal with this and suppress the decrease in the supply flow rate of the combustion air due to this increase. .

  In a second invention, in the first invention, the target rotational speed determination means determines the target rotational speed based on the burner combustion amount and the second closing correction value during the burn operation of the burner. A third blockage correction value indicating the blockage degree of the supply / exhaust passage is calculated from the relationship between the rotational speed of the fan and the fan current, and the increase in the blockage degree of the supply / exhaust passage is greater than the second level. When the difference between the first occlusion correction value and the second occlusion correction value indicates this, the process of setting the third occlusion correction value as the new second occlusion correction value is repeatedly executed.

  According to the second invention, the target rotational speed determination means continues to calculate the third blockage correction value from the relationship between the rotational speed of the fan and the fan current at each time point during the burner combustion operation, thereby blocking the supply / exhaust passage. When the difference between the second blockage correction value and the third blockage correction value indicates that the degree of increase is greater than the second level, the third blockage correction value is set as a new second blockage correction value. Therefore, when the degree of blockage of the supply / exhaust passage further increases during the burner combustion operation, the target rotational speed can be determined accurately so as to suppress a decrease in the supply flow rate of the combustion air due to this increase. Further, since the process of setting the third blockage correction value to the second blockage correction value is performed when there is a possibility that a combustion failure is likely to occur, the combustion is not deteriorated.

  According to a third aspect, in the first or second aspect, the target rotational speed determining means determines that the decrease in the degree of blockage of the air supply / exhaust passage is greater than a third level, the fourth blockage correction value and the second blockage correction value. The target rotational speed is determined on the basis of the burner combustion amount and the second closing correction value.

  According to the third invention, even when the degree of blockage of the supply / exhaust passage suddenly or temporarily decreases, the target rotational speed can be accurately determined so as to suppress the increase in the supply flow rate of the combustion air. . In addition, even when the correct blockage correction value is calculated after the combustion operation is stopped, it is possible to cope with a case where a change in the air volume temporarily occurs during combustion.

The block diagram which shows the structure of the fan control part of the combustion apparatus of this Embodiment. The graph which shows the relative relationship between the rotational speed of a fan, and a drive current. The figure which shows the 1st part of the operation | movement flowchart of the controller shown in FIG. The figure which shows the 2nd part of the operation | movement flowchart of the controller shown in FIG. The figure which shows the 3rd part of the operation | movement flowchart of the controller shown in FIG.

  FIG. 1 is a block diagram showing the configuration of the fan control unit of the combustion apparatus of the present embodiment. The fan 1 includes a fan motor 2 and a rotation speed sensor 3, and the operation of the fan 1 is controlled by a controller 4 including a microcomputer and a memory. The controller 4 sets the target combustion amount (Qa) of the burner according to the operating conditions (hot water supply temperature, heating temperature, etc.) of the combustion device by executing the control program for the combustion device held in the memory by the microcomputer. A burner combustion amount setting unit 6 that performs combustion, a target rotation speed determination unit 7 that determines a target rotation speed (Na) of the fan 1 that obtains combustion air corresponding to the target combustion amount (Qa), a combustion chamber in which the burner is accommodated, A correction coefficient determination unit 8 (corresponding to the blockage correction value calculation means of the present invention) that detects the blockage degree of the communication air supply / exhaust passage and determines the correction coefficient (H) of the target rotational speed (Na) according to the blockage degree. ), A target rotational speed correcting unit 9 (corresponding to the target rotational speed determining means of the present invention) that corrects the target rotational speed (Na) using the correction coefficient (H), and the corrected target rotational speed (Nb) Rotational speed A fan rotation speed control unit 10 (a fan of the present invention) that controls a current (Id, hereinafter referred to as fan current) supplied to the fan motor 2 so that the actual rotation speed (Ns) of the fan 1 detected by the sensor 3 matches. Functioning as control means).

  The reset switch 15 is used when a non-volatile memory (eg, flash memory) is used as the memory 11, and the volatile memory (eg, RAM) as the memory 11, that is, the power source of the combustion device is used. This is not necessary when using a memory that retains the memory only for a period in which it is on. Detailed description of the significance and the like of the reset switch 15 will be described later.

  The controller 4 is provided with a current sensor 5 (corresponding to the fan current sensor of the present invention) for detecting a fan current (Id) and a volatile memory 11 (corresponding to the storage means of the present invention). Then, the correction coefficient determination unit 8 detects the degree of blockage of the supply / exhaust passage from the change in the fan current (Id) detected by the current sensor 5 when the fan 1 is rotated at a predetermined blockage detection rotation speed.

  FIG. 2 is a graph showing the operating characteristics of the fan motor 2. The horizontal axis is set to the rotational speed (N) of the fan 1, and the vertical axis is set to the fan current (Id). In FIG. 2, 20 is a steady line showing the rotational speed-current characteristics of the fan 1 when the supply / exhaust passage is not blocked, and 21 is the rotation of the fan 1 when the correction coefficient (H) is 1.0. The speed-current characteristic is shown.

  Reference numeral 21 denotes a reference line for determining whether or not to perform correction. As the supply / exhaust passage is closed, the rotational speed-current characteristic of the fan 1 changes to 23 and 24 in the figure, and the fan current (required for operating the fan 1 at the closed detection rotational speed (Nt)). Id) gradually decreases. Reference numeral 24 denotes an auxiliary value line for the rotational speed-current characteristic of the fan 1 that is predetermined by experiment to obtain the correction coefficient (H).

I ₃ and I ₁ are the fan current values in the auxiliary value line 24 and the reference value line 21 when the rotation speed of the fan 1 is the blockage detection rotation speed (Nt), respectively, and I ₂ is the rotation speed of the fan 1. The detected current value of the current sensor 5 at the blocking detection rotational speed (Nt), a is the difference between I ₁ and I ₃ (a = I ₁ −I ₃ ), and b is the difference between I ₂ and I ₃ (b = is an I ₂ -I _3).

And the correction coefficient determination part 8 calculates a correction coefficient (H) by the following formula | equation (1). In the actual application, the correction coefficient (H) of the equation (1) is calculated as a first correction coefficient (Ha), a second correction coefficient (Hb), or a third correction coefficient (Hc) described later. When the first correction coefficient (Ha) is calculated by the expression (1), a and b on the right side of the expression (1) indicate the blockage detection rotation in which the actual rotation speed of the fan 1 is calculated by the expression (3) described later. The fan current (id = I ₂ ) at that time is detected at the speed (Nt), and is calculated based on the intersection of the blockage detection rotation speed and the fan current in FIG. On the other hand, when the second correction coefficient (Hb) or the third correction coefficient (Hc) is calculated by the expression (1), a and b on the right side of the expression (1) block the actual rotational speed of the fan 1. Without the detected rotational speed (Nt), the current fan rotational speed and fan current (Id = I ₂ ) during the combustion operation are detected and calculated based on the intersection of the fan rotational speed and the fan current in FIG.
H = {(a / b) −1} × α + 1 (1)
Where α is a constant of 1 or less determined by experiments or simulations.

Here, as the degree of blockage of the air supply / exhaust passage increases, the pressure in the air supply / exhaust passage decreases, so the detected current (I ₂ ) of the current sensor 5 at the supply / discharge blockage detection rotational speed (Nt) decreases. Therefore, a / b in the above formula (1) increases and the correction coefficient (H) increases. Since the target rotational speed correction unit 9 corrects the target rotational speed (Na) by the following equation (2), the corrected target rotational speed (Nb) is set higher as the air supply / exhaust passage blockage degree increases. Is done.

Nb = H × Na (2)
The target rotational speed (Na) is the target rotational speed of the fan 1 that can obtain combustion air corresponding to the target combustion amount (Qa), as described above. Since the corrected target rotational speed (Nb) is determined based on the correction coefficient (H) and the target rotational speed (Na), the burner combustion amount, the first closing correction value (Ha), and the second closing correction value (Hb) or the third occlusion correction value (Hc). The first correction coefficient (Ha), the second correction coefficient (Hb), and the third blockage correction value (Hc) correspond to the first blockage correction value, the second blockage correction value, and the third blockage correction value of the present invention, respectively. The first blockage correction value, the second blockage correction value, and the third blockage correction value of the present invention indicate the blockage degree of the supply / exhaust passage, and the fan target rotational speed reflecting the blockage degree of the supply / exhaust passageway. It is assumed that the value is defined as a value used for the calculation, and may be a coefficient, or may be a predetermined term or a corresponding constant in the calculation formula for the fan target rotation speed.

  Next, the operation of the controller 4 will be described according to the flowcharts shown in FIGS. 3 to 5 with reference to FIGS. In FIG. 3, when a power switch (not shown) is turned ON in STEP 1 and power supply to the combustion apparatus is started, the controller 4 first sets the correction coefficient (H) to an initial value of 1.0 in STEP 2. It is set and stored in the memory 11, the counter variable (CNT) is cleared in STEP 3, and the operation switch (not shown) is waited for an ON operation in STEP 4.

  When the operation switch is turned ON, the process proceeds from STEP 4 to STEP 5, and the controller 4 starts the burner combustion operation. Specifically, the controller 4 reads out the fourth correction coefficient (Ha. The relationship between the first correction coefficient (Ha) and the fourth correction coefficient (Ha) will be described later) from the memory 11, and the correction coefficient (H). Is substituted by the burner combustion amount setting unit 6, the target rotational speed determination unit 7, the correction coefficient determination unit 8, the target rotational speed correction unit 9, and the fan rotational speed control unit 10 described above. Then, the rotational speed control for maintaining the rotational speed of the fan 1 at the corrected target rotational speed (Nb) is executed. The corrected target rotational speed (Nb) is determined based on the above formula (2) from the target rotational speed (Na) and the correction coefficient (H) substituted with the fourth correction coefficient (Ha) read from the memory 11. It is the value.

  The relationship between the first correction coefficient (Ha) calculated by the above equation (1) and the fourth correction coefficient (Ha) stored in the memory 11 will be described. The fourth correction coefficient (Ha) may be the first correction coefficient (Ha) itself or may be a value obtained by correcting the first correction coefficient (Ha), that is, the following STEP 35, 36, 43, 44, 50, and 80, if the determination in STEP 35 or 43 is negative, the first correction coefficient (Ha) is stored as it is in the memory 11 as the fourth correction coefficient (Ha). , 43 is positive, it is stored in the memory 11 as the fourth correction coefficient (Ha) after the amount of increase with respect to the fourth correction coefficient (Ha) before the update is limited.

  The fourth correction coefficient (Ha) is defined as a correction coefficient stored in the memory 11 without correction or correction with respect to the first correction coefficient (Ha). The fourth correction coefficient (Ha) corresponds to the “fourth closing correction value” of the present invention.

  In STEP 6, the controller 4 starts a 10 minute timer. 10 minutes of the set time of the 10 minute timer is an example, and the set time of the timer is a time during which the resistance to the combustion air flowing through the supply / exhaust passage and the combustion exhaust gas of the burner is stable and the fluctuation of the fan current (Id) decreases. The longer time can be set according to the form of the combustion device.

  The controller 4 confirms whether or not the correction coefficient (H) is 1.36 or more in STEP7. When the correction coefficient (H) is 1.36 or more, it is branched to STEP 8 and the fact that the supply / exhaust passage is closed is turned on by an error lamp (not shown) or a buzzer (not shown) ringing. To inform.

  In STEP 9, the correction coefficient determination unit 8 detects the fan current (Id) at the current fan rotation speed by the current sensor 5, and in STEP 10, based on the fan current (Id), the second correction is performed by the above equation (1). A coefficient (Hb) is calculated.

  In STEP 11, the controller 4 confirms whether or not Hb−Ha is equal to or less than a predetermined positive constant C <b> 1. When Hb−Ha ≦ C1, the process proceeds to STEP12, and when Hb−Ha> C1, the process proceeds to STEP13 (FIG. 4). C1 corresponds to the difference between the first closing correction value and the second closing correction value corresponding to the first level of the present invention regarding the increase in the closing degree of the supply / exhaust passage.

  “Hb−Ha ≦ C1” in STEP 11 can be replaced with “| Hb−Ha | ≦ C1”. | Hb−Ha | means the absolute value of Hb−Ha. The significance of the replacement will be described later as a modification of this embodiment.

  The controller 4 confirms whether or not the operation stop condition (OFF operation of the operation switch, end of the timer operation, etc.) is satisfied in STEP12. If the operation stop condition is satisfied, the combustion of the burner is immediately stopped, and then the process proceeds to STEP 21 (FIG. 4). If the operation stop condition is not satisfied, the process returns to STEP9.

  In FIG. 4, the controller 4 substitutes the second correction coefficient (Hb) for the correction coefficient (H) in STEP13. As a result, the controller 4 re-corrects the target rotational speed (Nb) of the fan 1 using the updated correction coefficient (H) substituted with the second correction coefficient (Hb) in the above equation (2), The rotation speed control of the fan 1 is switched to the rotation speed control that maintains the rotation speed of the fan 1 at the target rotation speed (Nb) after re-correction.

  The processing of STEPs 14 and 15 is the same as the processing of STEPs 7 and 8 (FIG. 3) described above. That is, the controller 4 confirms whether or not the correction coefficient (H) is 1.36 or more in STEP14. When the correction coefficient (H) is 1.36 or more, it is branched to STEP 15 and the fact that the supply / exhaust passage has been closed is turned on by an error lamp (not shown) or a buzzer (not shown). To inform.

  The processing of STEPs 16, 17, and 20 is the same as the processing of STEPs 9, 10, and 12 (FIG. 3) described above. That is, the correction coefficient determination unit 8 detects the fan current (Id) at the current rotation speed by the current sensor 5 in STEP 16, and in STEP 17, based on the fan current (Id), the third equation (1) A correction coefficient (Hc) is newly calculated.

  In STEP 18, the controller 4 confirms whether or not Hc−Hb is equal to or smaller than a predetermined positive constant C2. “C2” in STEP 18 is C2 = C1 in the present embodiment, but may be C2 ≠ C1. C2 corresponds to the difference between the first closing correction value and the second closing correction value corresponding to the second level of the present invention regarding the increase in the closing degree of the supply / exhaust passage. When Hc−Hb> C2, the process proceeds to STEP 19, after Hc is substituted for Hb, the process returns to STEP13. On the other hand, when Hc−Hb ≦ C2, the process proceeds to STEP20.

  “Hc−Hb ≦ C2” in STEP 18 may be replaced with “| Hc−Hb | ≦ C2”. | Hc-Hb | means the absolute value of Hc-Hb. The significance of the replacement will be described later as a modification of this embodiment.

  Thus, as long as the combustion operation is maintained even after changing the correction coefficient (H) once from the fourth correction coefficient (Ha) to the second correction coefficient (Hb), the latest fan current (Id) at each time point is maintained. When the third correction coefficient (Hc) is calculated based on the above, and Hc−Hb> C2, the second correction coefficient (Hb) is re-assigned to the third correction coefficient (Hc), and the correction coefficient (H) is calculated. The process of updating to the second correction coefficient (Hb) after the change is repeated. Thereby, it is possible to appropriately increase the fan rotation speed with respect to the second or subsequent sudden increase in the degree of blockage of the supply / exhaust passage during the combustion operation.

  The controller 4 checks whether or not the operation stop condition (OFF operation of the operation switch, end of the timer operation, etc.) is satisfied in STEP20. When the operation stop condition is satisfied, combustion of the burner is immediately stopped, and then the process proceeds to STEP 21 where the controller 4 determines whether or not the 10-minute timer has expired, that is, whether the combustion operation has been continued for 10 minutes or more. Confirm whether or not. If the 10-minute timer has not expired, the process proceeds to STEP 22 where the controller 4 operates the fan 1 for a predetermined time (for example, 5 seconds) to purge the combustion chamber and return to STEP 4 in FIG. Waiting for switch operation.

  On the other hand, when the 10-minute timer is up, it can be determined that the entire combustion apparatus is heated and can stably detect the blockage degree of the supply / exhaust passage by continuous combustion operation. According to STEP 31 to STEP 36, STEP 40 to STEP 44, and STEP 50, 51, and 80 in FIG. 5, the correction coefficient determination unit 8 executes a process of determining the first correction coefficient (Ha). Specifically, when the first correction coefficient (Ha) does not exceed a predetermined upper limit with respect to the fourth correction coefficient (Ha) of the memory 11, no correction is performed and when the first correction coefficient (Ha) exceeds the predetermined upper limit. Is replaced with the fourth correction coefficient (Ha) + the upper limit and stored in the memory 11 as the fourth correction coefficient (Ha). In the present embodiment, the volatile memory 11 is employed. However, when the nonvolatile memory is used, the fourth correction coefficient (Ha) determined last time after the combustion apparatus is turned off. Is stored in the memory 11, the processing of STEP 40 to STEP 44 and STP 50, 51 of FIG.

  First, in STEP 31, the correction coefficient determination unit 8 determines whether or not the current combustion operation is the first (first) combustion operation after the combustion apparatus is powered on. Then, when it is the first combustion operation after the power is turned on, the process branches to STEP 40, where the correction coefficient determination unit 8 stores the fourth correction coefficient (Ha, which is 1 in the initial value in this case) stored in the memory 11. Is set to 0.0), the blockage detection rotation speed (Nt) is calculated by the following equation (3), and the fan is operated at the blockage detection rotation speed (Nt).

Nt = Ni × {(Ha−1) × A + 1} (3)
Where Ni is a preset initial value of the blocking detection rotation speed, and A is a constant determined by experiments or simulations.

  Thereby, the blockage detection rotation speed (Nt) is set higher as the blockage degree of the supply / exhaust passage increases. Therefore, the fan current (Id) at the time of blockage detection decreases due to blockage of the air supply / exhaust passage, the value of b in FIG. 2 decreases, and the calculation accuracy of the first correction coefficient (Ha) by the above equation (1) is improved. Prevents the decline.

  In the next STEP 41, the correction coefficient determination unit 8 detects the fan current (Id) at the blockage detection rotational speed (Nt), and in STEP 42, based on the fan current (Id), the first correction is performed by the above equation (1). A coefficient (Ha) is calculated. In the next STEP 43, when the difference (ΔHa) between the first correction coefficient calculated this time and the fourth correction coefficient stored in the memory 11 exceeds 0.05, the process branches to STEP 50.

  Here, the value of 0.05 is set to prevent erroneous detection of the degree of blockage when the air resistance of the supply / exhaust passage increases or decreases momentarily due to the blowing of gusts into the supply / exhaust passage. And a value set to see the stability of the air flow rate in the air supply / exhaust passage. When the difference (ΔHa) between the first correction coefficient calculated this time and the fourth correction coefficient stored in the memory 11 exceeds 0.05, the correction coefficient determination unit 8 determines the fourth correction coefficient ( After increasing Ha) by 0.04, the fourth correction coefficient (Ha) increased in STEP 51 is stored in the memory 11.

  Although the increment of the fourth correction coefficient (Ha) in STEP 51 is set to 0.04, which is smaller than the upper limit (0.05) in STEP 43, the increment may be set to the same value as the upper limit. Good.

  The correction coefficient determination unit 8 performs steps 40 to 42 and STEPs 50 and 51 until the difference (ΔHa) between the first correction coefficient calculated this time in STEP 42 and the fourth correction coefficient stored in the memory 11 becomes 0.05 or less. Repeat the process. Thus, when the power supply / exhaust passage is already closed when the power is turned on and the fourth correction coefficient (Ha) needs to be set to a large value, the first correction coefficient (Ha) is set to 0. It can be gradually increased by 04.

  Therefore, even when the correction coefficient determination unit 8 needs to set the fourth correction coefficient (Ha) to a large value, the correction coefficient determination unit 8 eliminates the influence of the gust blowing into the supply / exhaust passage described above, Four correction factors (Ha) can be determined.

  Then, when the difference (ΔHa) between the first correction coefficient and the fourth correction coefficient becomes 0.05 or less in STEP 43, the process proceeds to STEP 44, and the correction coefficient determination unit 8 sets the calculated first correction coefficient (Ha). The program is stored and updated in the memory 11, and the process proceeds to STEP37.

  On the other hand, when it is not the first combustion operation after turning on the power in STEP 31, the process proceeds to STEP 32, and the correction coefficient determination unit 8 operates the fan 1 at the blockage detection rotational speed (Nt) stored in the memory 11. Here, the blockage detection rotation speed (Nt) is calculated according to the above equation (3) using the fourth correction coefficient (Ha) calculated according to the previous detection result of the blockage degree of the supply / exhaust passage and stored in the memory 11. ). Therefore, the blockage detection rotational speed (Nt) is set higher as the blockage of the supply / exhaust passage proceeds, and the fan current necessary for detection of the blockage of the supply / exhaust passage is secured.

  In this case, after the combustion operation is stopped in STEP 20, the correction coefficient determination unit 8 is within a predetermined time (the maximum time (for example, 10 seconds) required for the fan 1 to reach the blockage detection rotational speed (Nt)). The fan current (Id) at the blockage detection rotational speed (Nt) can be detected. Therefore, the correction coefficient determination unit 8 at STEP 33 at the blockage detection rotation speed (Nt) in a state where the air resistance and the fan current (Id) of the supply / exhaust passage are stabilized by executing the continuous combustion operation for 10 minutes or more. The fan current (Id) can be detected with high accuracy.

  In the next STEP 34, the correction coefficient determination unit 8 detects the fan current (Id) by the current sensor 5, and based on the fan current (Id), the correction coefficient determination unit 8 calculates the first correction coefficient (Ha) by the above formula (1). calculate.

  The next STEP 35 is similar to STEP 43 described above, when the degree of blockage of the air supply / exhaust passage is erroneously detected higher than the actual due to the influence of gust blowing into the air supply / exhaust passage, etc. 4 This is to prevent the correction coefficient (Ha) from being changed. When the difference (ΔH) between the first correction coefficient calculated this time and the fourth correction coefficient stored in the memory 11 is 0.04 or less, the correction coefficient determination unit 8 calculates the first correction coefficient calculated this time in STEP 36. The correction coefficient (Ha) is stored in the memory 11 as the fourth correction coefficient (Ha), and the fourth correction coefficient (Ha) is updated.

  On the other hand, when the difference (ΔHa) between the first correction coefficient (Ha) calculated this time and the fourth correction coefficient (Ha) stored in the memory 11 exceeds 0.04 in STEP 35, the process branches to STEP 80. The correction coefficient determination unit 8 adds 0.04 to the correction coefficient stored in the memory 11, and then stores the added fourth correction coefficient (Ha) in the memory 11 in STEP 36. (Ha) is updated. Thereby, the correction coefficient determination unit 8 prevents the fourth correction coefficient (Ha) from being extremely changed due to the influence of the gust.

  In subsequent STEP 37, the controller 4 confirms whether or not the fourth correction coefficient (Ha) stored in the memory 11 is 1.4 or more, which is a blockage determination reference value for the supply / exhaust passage. When the fourth correction coefficient (Ha) is 1.4 or more, the process branches to STEP 60, and the controller 4 counts up the counter variable (CNT).

  In the next STEP 61, when the count variable (CNT) is 3 or more, that is, when the fourth correction coefficient (Ha) is 1.4 or more continuously for 3 times, the controller 4 closes the supply / exhaust passage. Branching to STEP 70 and waiting for the ON operation of the operation switch. When the operation switch is turned ON, the process proceeds to STEP 71, where the controller 4 notifies the user that the supply / exhaust passage is blocked by lighting an error lamp or ringing a buzzer, and prohibits the execution of the combustion operation. .

  If the fourth correction coefficient (Ha) is less than 1.4 in STEP 37, the process proceeds to STEP 38, where the controller 4 clears the count variable (CNT) and returns to STEP 4 in FIG. Wait for ON operation.

  In this way, the correction coefficient determination unit 8 immediately after the combustion operation is continued for 10 minutes or more and the combustion apparatus is entirely heated to extinguish the combustion operation, and the combustion air and burner flowing through the supply / exhaust passage While the resistance to the combustion exhaust gas is stabilized and the fluctuation of the fan current (Id) is reduced, the fan 1 is rotated at the blockage detection rotational speed (Nt) to detect the fan current (Id). Therefore, the correction coefficient determination unit 8 can accurately detect the fan current (Id) that varies in accordance with the degree of blockage of the supply / exhaust passage, and the target rotational speed of the fan 1 based on the detected fan current (Id). The fourth correction coefficient (Ha) can be determined with high accuracy.

  The reset switch 15 in FIG. 1 will be described. The reset switch 15 is provided in the controller 4 when the memory 11 is nonvolatile. When the reset switch 15 is operated, the fourth correction coefficient (Ha) stored in the memory 11 by the controller 4 is set as an initial value (Ha = 1.0). By providing the reset switch 15, when the blockage of the supply / exhaust passage is eliminated by maintenance, the maintenance operator operates the reset switch 15 to set the fourth correction coefficient (Ha) to block the supply / exhaust passage. It can be returned to the initial value corresponding to the state that is not.

  The modification of FIGS. 3-5 is demonstrated. In STEP 18 (FIG. 4), it is confirmed whether or not Hc−Hb ≦ C2, but instead of this, | Hc−Hb | ≦ C2 may be satisfied. In this case, not only when Hc−Hb> C2, but also when Hb−Hc> C2, that is, when the degree of blockage decreases, the second correction coefficient (Hb) is changed to the third correction coefficient (Hc) in STEP19. In step 13, the updated second correction coefficient (Hb) is substituted into the correction coefficient (H) in STEP 13, and as a result, the target rotational speed of the fan is lowered. For example, after storing the fourth correction coefficient (Ha) in the memory 11 until the current combustion operation, a sudden or temporary blockage occurs in the supply / exhaust passage, and the correction coefficient (H) becomes the fourth correction coefficient. It is changed in STEP13 from (Ha) to the second correction coefficient (Hb), and then the sudden or temporary blockage may be released during the same combustion operation. Even when Hb-Ha> C2 in STEP 18, returning from STEP 18 to STEP 13 via STEP 19 reduces the degree of blockage of the supply / exhaust passage when sudden or temporary blockage is released during combustion operation. Even if it responds, it can respond appropriately.

  As another modification, confirmation of whether or not Hb−Ha ≦ C1 in STEP 11 (FIG. 3) may be replaced with confirmation of whether or not | Hb−Ha | ≦ C1. That is, in STEP 11, not only confirmation of Hb−Ha ≦ C1 but also confirmation of Ha−Hb ≦ C1 is performed. C1 in the case of Ha−Hb ≦ C1 corresponds to the difference between the fourth blockage correction value and the second blockage correction value corresponding to the third level of the present invention regarding the decrease in the blockage degree of the supply / exhaust passage. When | Hb−Ha | ≦ C1 is confirmed, it is between the end of the previous combustion operation and the start of the next combustion operation or during the next combustion operation after the start of the next combustion operation. In the next combustion operation, when the degree of blockage of the supply / exhaust passage is reduced after cleaning of the supply / exhaust passage or removal of the curing sheet partially blocking the supply / exhaust passage, etc., from STEP 11 to FIG. It branches to STEP13 and the 2nd correction coefficient (Hb) according to the condition of the supply / exhaust passage where the blockage degree decreased can be calculated. Then, by determining the target rotational speed of the fan using the second correction coefficient (Hb) calculated in this way, supply of combustion air to the burner when the degree of blockage of the supply / exhaust passage decreases. It is possible to appropriately control the amount of combustion air supplied by preventing the amount from becoming excessive.

DESCRIPTION OF SYMBOLS 1 ... Fan, 2 ... Fan motor, 3 ... Rotation speed sensor, 4 ... Controller, 5 ... Current sensor, 6 ... Burner combustion amount setting part, 7 ... Target rotation Speed determination unit, 8... Correction coefficient determination unit, 9... Target rotation speed correction unit, 10.

Claims (3)

A combustion chamber containing a burner;
A fan that is provided in a supply / exhaust passage communicating with the combustion chamber and that supplies combustion air to the burner and exhausts combustion exhaust gas from the burner;
A rotational speed sensor for detecting the rotational speed of the fan;
A fan current sensor for detecting a fan current supplied to the fan;
Fan control means for controlling the fan current so that the target rotational speed of the fan becomes a target rotational speed corresponding to the amount of combustion of the burner during the combustion operation of the burner;
After the burner combustion operation has continued for a predetermined time or longer, after the burner has stopped burning, the fan is operated at a predetermined blockage detection rotation speed, and is operated at the blockage detection rotation speed and the blockage detection rotation speed. A blockage correction value calculating means for maintaining and updating the fourth blockage correction value held in the storage means by the first blockage correction value indicating the blockage degree of the supply / exhaust passage from the relationship with the fan current at the time;
During the combustion operation of the burner, a second blockage correction value indicating the blockage degree of the supply / exhaust passage is calculated from the relationship between the rotation speed of the fan and the fan current, and the increase of the blockage degree of the supply / exhaust passage is increased. When the difference between the fourth blockage correction value and the second blockage correction value indicates that the level is equal to or lower than the first level, the target rotation is based on the burner combustion amount and the fourth blockage correction value. When the speed is determined and the difference between the fourth blockage correction value and the second blockage correction value indicates that the increase in the blockage degree of the supply / exhaust passage is greater than the first level, the combustion amount of the burner And a target rotational speed determination means for determining the target rotational speed based on the second blockage correction value. The combustion apparatus according to claim 1, wherein
The target rotational speed determining means determines the target rotational speed based on the combustion amount of the burner and the second closing correction value during the burn operation of the burner, From the relationship with the fan current, a third blockage correction value indicating the blockage degree of the supply / exhaust passage is calculated, and the increase in the blockage degree of the supply / exhaust passage is greater than a second level and the second blockage correction value and the When the difference from the third occlusion correction value indicates, the combustion apparatus is characterized by repeatedly executing the process of setting the third occlusion correction value as the new second occlusion correction value. The combustion apparatus according to claim 1 or 2,
The target rotational speed determination means is also operable when the difference between the fourth blockage correction value and the second blockage correction value indicates that the decrease in the blockage degree of the supply / exhaust passage is greater than a third level. The combustion apparatus characterized in that the target rotational speed is determined based on a burner combustion amount and the second closing correction value.

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