JP2002005436A - Combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the deficient air supply period during combustion control. SOLUTION: A motor current detecting section 9k detects a motor current Id, a voltage/temperature correcting section 9m corrects the current value Id and a relation calculating section 9h calculates the coefficient a3 of the cubic function of r.p.m. based on data from a load data detecting section 9i and the corrected current value. Normal operation, improved operation, capacity limited operation or abnormal stoppage is performed depending on the magnitude of a3 indicative of a blocking level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus having a fan disposed in a supply / exhaust passage, and more particularly, to a combustion apparatus for correcting the number of revolutions of a fan according to a blockage level.

[Prior art]

2. Description of the Related Art Conventionally, in a combustion apparatus in which combustion air is sucked by a fan and burned, an air supply filter is clogged with dust or oil and a supply / exhaust passage is blocked, so that the number of rotations of the fan is simply determined according to the amount of gas. , The predetermined air-fuel ratio cannot be maintained. In this state, the amount of combustion air is insufficient and the combustion proceeds to incomplete combustion, and the generation of soot may cause the fins of the heat exchanger to be clogged, resulting in poor exhaust. For this reason, in such a combustion device, the current value and the rotation speed of the fan motor are detected, and when the current value when the fan is rotating at the predetermined rotation speed falls below the predetermined value, the blockage level increases. In some cases, a correction is made to increase the number of revolutions to perform an improved operation, and when the number of revolutions reaches the limit number of revolutions of the fan, the operation of the appliance is stopped.

[0003] In such a combustion apparatus, before stopping the operation of the appliance, the user is first notified of an abnormality in the air supply / exhaust system by displaying an error code or the like. Immediately after the fan reaches the limit rotational speed due to the correction, the operation of the appliance is stopped, and the appliance cannot be used thereafter.

[0004] In the combustion apparatus disclosed in Japanese Patent No. 2975506, when the burner burns, when the rotation speed reaches the limit, the upper limit of the burner combustion amount is reduced to reduce the required ventilation volume. Combustion can be continued. That is, by setting the upper limit value of the combustion amount to be lower, the fan rotation speed for obtaining an appropriate air-fuel ratio is lower than the limit rotation speed, so that the combustion can be continued.

In such a combustion apparatus, as shown in FIG. 3, the fan is controlled at a rotation speed N in accordance with the combustion amount Ip. However, when a blockage is detected, the rotation speed N is adjusted to compensate for insufficient air supply. Improved operation is performed with increasing correction. For example,
When the combustion amount Ip is Ipa, the rotational speed is set to Nc (in the figure,
From the lower line) to Nd (the upper line in the figure).

In the case where the combustion amount Ip is large, if the rotation speed N is increased for an improved operation, the corrected rotation speed may reach the limit rotation speed Nltd of the fan. By lowering the upper limit of Ip so that the corrected rotation speed becomes equal to or lower than the limit rotation speed Nltd, an attempt is made to achieve good combustion even at the expense of the combustion amount Ip. For example, when the combustion amount Ip is equal to the maximum combustion amount Ipmax, the rotational speed Na is increased and corrected each time a blockage is detected (indicated by a broken line arrow in the figure), and the corrected rotational speed N becomes the limit rotational speed Nltd.
, The upper limit of the combustion amount Ip is reduced from Ipmax to Ipa for the first time. If the corrected rotation speed Nd after the performance limitation is in a range smaller than the limit rotation speed Nltd, the fan rotates at the corrected rotation speed Nd to perform the improved operation. If the corrected rotation speed Nd exceeds the limit rotation speed Nltd even after the performance limitation, the operation of the appliance is stopped.

[0007]

However, in such control, the fan rotation speed is increased and corrected every time a blockage is detected, and the corrected rotation speed N becomes the limit rotation speed Nlt.
Since the capacity limitation is performed only after reaching d, the control from the blockage detection to the capacity limitation takes a long time, and the air supply shortage period becomes long. In addition, when the device is significantly blocked, the operation of the device should be stopped immediately after the blockage is detected.First, the improvement operation is performed, and then the operation is stopped only after performing the capacity limitation operation. It takes a very long time from the start to the stop of operation, and a large amount of harmful gas is generated due to incomplete combustion. Therefore, it is an object of the present invention to solve the above-described problems and to reduce a short supply period during the combustion control.

[0008]

According to a first aspect of the present invention, there is provided a combustion apparatus for adjusting a combustion amount of a burner, and an amount of combustion air corresponding to the combustion amount. To the burner, blockage level detecting means for detecting a blockage level of the supply / exhaust path, and fan motor control means for correcting a target drive control amount of the fan based on the blockage level from the blockage level detector In performing the correction of the fan, if the blockage level is equal to or higher than the first severe level, the operation of the appliance is immediately stopped without performing the correction, and the blockage level is set to the first severe level. If the blockage level is less than the mild second level, the upper limit value of the combustion amount is reduced to a predetermined limit value, and the correction control is performed.
A cow is provided with combustion control means for performing correction control without lowering the upper limit of the combustion amount.

According to the combustion apparatus of the first aspect of the present invention having the above structure, when correcting the fan, the target drive control amount of the fan is corrected when the blockage level is equal to or more than the first severe level. Even if the supply / exhaust passage is not completely blocked, the operation of the appliance is immediately stopped without performing the correction control. As a result, the combustion time when the supply / exhaust system is abnormal can be shortened, and incomplete combustion can be quickly prevented. When the blockage level is between the first severe level and the second mild level, first, the upper limit value of the combustion amount is reduced to a predetermined limit value, and the correction control is performed. That is, the setting for limiting the maximum combustion amount is performed. As a result, the amount of ventilation required for the combustion is reduced, and even if the fan is rotated at less than the maximum rotation speed, it is possible to sufficiently cope with the blockage of the supply / exhaust passage. Moreover, since the capacity is limited before the corrected rotational speed reaches the limit rotational speed, the control time from the detection of the blockage level detecting means to the setting for lowering the upper limit of the combustion amount can be shortened. In addition, when the blockage level is equal to or less than the second level which is mild, the fan is rotated at the target drive control amount corresponding to the blockage level without lowering the upper limit of the combustion amount, and even if the supply / exhaust system is slightly blocked. Good combustion is achieved by such improved operation. Thus, appropriate combustion control is performed according to the blockage level.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of a combustion apparatus of the present invention will be described below.

FIG. 2 is a schematic configuration diagram of a water heater 1 as one embodiment of the present invention. The water heater 1 includes a burner 13 that burns fuel gas, a heat exchanger 2 that heats water in a water passage by burning the burner 13, a heat exchanger 2, and a burner 13.
It has a combustion chamber 3 forming a combustion space therebetween, and a fan F for sending combustion air from the bottom to the combustion chamber 3.

Further, the water passage is connected to the heat exchanger 2 through the water supply passage 5.
Through a hot water supply path 6 (not shown). The water supply path 5 is provided with an incoming water temperature thermistor S1 for detecting the incoming water temperature and a flow rate sensor S2 for detecting the amount of incoming water, and the outgoing water temperature for detecting the outgoing water temperature after heat exchange is provided in the hot water supply path 6. A sensor S3 is provided.

On the other hand, the gas supply path 10 to the burner 13 is provided with, from the upstream side, a main solenoid valve MV1 for opening and closing the flow path, a proportional solenoid valve MV2 for controlling the amount of fuel gas, and a main solenoid valve MV3. Can be Further, the burner 13 is provided with an electrode 12 for igniting gas by continuous discharge and a frame rod 11 for detecting a combustion flame. These are electrically connected to the controller 9 to perform predetermined control such as ignition, tapping and stopping. The fan F is provided with a fan motor M
The fan motor M is controlled so as to reach a target rotation speed determined with respect to the combustion amount Ip, and supplies the combustion chamber 3 with combustion air in an amount corresponding to the fuel gas amount. An air supply temperature sensor S4 for detecting an air supply temperature Tz is provided at an air supply port of the fan F.

A remote control remote control (not shown) is connected to the controller 9, and the remote control includes an operation switch,
A tap water temperature setting unit and an alarm lamp for notifying an abnormality of the blockage level are provided. The controller 9 is mainly composed of a microcomputer, and can be broadly classified based on its functions. The controller 9 detects a hot water temperature, an incoming water temperature, and a flow rate, and controls the fuel gas amount of the burner 13 so as to reach the target hot water temperature. Control unit 9a
A fan motor control unit 9c that controls the number of revolutions of the fan F by a signal from the hot water supply control unit 9a to supply combustion air in accordance with the amount of fuel gas, a blockage level detection unit 9g that detects a blockage level, An abnormality processing section 9p for turning on an alarm lamp to stop combustion when the detected blockage level is equal to or higher than a predetermined level (abnormal level).

The block level detector 9g stores load data (motor current, motor voltage,
A load data detection unit 9i for detecting a rotation speed) and a relational expression calculation unit 9h for calculating a relational expression to be described later from the detected load data are provided. The load data detection unit 9i includes a rotation speed detection unit 9j that detects the rotation speed of the fan motor M based on the rotation pulse from the fan motor M, and a motor current detection unit 9k that detects the motor current Id of the fan motor M. And a motor voltage detector 9n for detecting a voltage Vd applied to the fan motor M. The motor current detector 9k includes a voltage / temperature corrector 9m for correcting the motor current detected based on the applied voltage Vd detected by the motor voltage detector 9n and the supply air temperature Tz detected by the supply air temperature sensor S4. Is provided.

The fan motor control section 9c is provided with a rotation correction section 9d for correcting the fan rotation speed based on the detection result of the blockage level detection section 9g, and the hot water supply control section 9a is provided with a blockage level detection section. When the blockage level detected by the section 9g is excessively increased, a capacity limiting section 9b for limiting the maximum capacity of the water heater 1 to 65% thereof is provided.

Next, the blockage level detecting section 9g of the controller 9 will be described. This blockage level detector 9g
A relational expression is calculated from the detected rotation speed, motor current, and load data of the motor voltage, and the abnormality processing unit 9p, the capacity limiting unit 9b, and the rotation speed correction unit 9d are determined by the level of the blockage level detected from the relational expression. Transmit the detection result.

Here, the relational expression used in the present embodiment and coefficients relating to the closing level of the relational expression will be described. Generally, a pulse width modulation control method (PWM) is used.
It is known that the following relational expression is established in the fan motor M of (lation). ^{_{I = a 3 N 3 + a}} 2 N 2 + a 1 N + a 0 ... formula a _3: coefficient relating to the closing level _{a 2, a 1, a 0} : where coefficients of the fan motor, a ₂ of the secondary coefficients, ignores Since it is as small as possible, this quadratic term is omitted to shorten the calculation time. Therefore, the equation can be rewritten as: I = a ₃ N ³ + a ₁ N + a ₀ ...

Next, a blockage level detection process performed using this equation will be described with reference to FIG. Hot water supply controller 9a
Opens the original solenoid valve M1 and the main solenoid valve MV3, ignites the fuel gas of the burner 13 by the continuous discharge of the electrode 12 to start combustion, and sets the proportional solenoid valve MV2 so that the hot water temperature becomes the target temperature. The control is started to control the fuel gas amount.
Along with the start of the combustion control, a blockage level detection process is started. First, the flow state is detected by the flow rate sensor S2, and it is determined whether or not water is flowing (during combustion) (S1).

When burning, the amount of combustion (input)
It is determined whether Ip is stable (S2). If it is determined that the input is stable, the process proceeds to step 3, where the motor current value Id is detected.

The voltage / temperature correction unit 9m converts the current value Id into a current value Iv at the time of the reference voltage Vs according to the following equation (hereinafter referred to as voltage correction). _{Iv = (Id-a 0 "} ) × Vd / Vs + a 0" ... the formula Id: detected current value Iv: current value was Id voltage correction Vs: reference voltage value Vd: the detected voltage value a ₀ ": when post-purge The coefficient a ₀ ″ and a ₁ ″ in the equation to be described later use a value preset in the controller 9 when the operation is started for the first time and post-purge has not been experienced.

Further, since the air density changes in accordance with the supply air temperature Tz and the load of the fan motor M differs, the voltage / temperature correction section 9m corrects the voltage-corrected current value Iv by the following equation to correct the current. The value Ic is calculated (hereinafter, referred to as temperature correction). Ic = {(Iv−a ₀ ″) × (273 + Tz) / (273 + 20)} + a ₀ ″ Formula Iv: Voltage-corrected current value Ic: Iv-temperature corrected current value Tz: Supply air temperature (° C.) ( Outside air temperature) a ₀ ″: coefficient smoothed during post-purging

[0023] Subsequently, on the basis of data relation calculator 9h is due to load data detector 9i, calculates the coefficient a ₃ of the third-order terms relating to supply and exhaust the load resistance by the following equation obtained by modifying the formula. _{a 3 = (Ic-a 1} "Nd-a 0") / Nd 3 ... Formula a ₁ ", a _0": coefficients of the terms in which the smoothing operation in blockage level detection when post-purge Nd: rotational speed detected in this case, the primary non-coefficient a ₃ of the cubic term coefficient of 0-order terms, as described later, coefficients a ₁ and a smoothing operation by clogging level detection in the previous post-purge ", a _0" Is used as it is. This is to suppress variations by using a smooth and stable value. Note that the coefficient a _{3 of the} third order term
It has been found from experimental data that the occlusion level increases with decreasing.

In the improved operation described below, the rotation speed Nd of the fan motor M is adjusted so that the air-fuel ratio is kept constant, in order to prevent incomplete combustion due to a decrease in the air volume due to an increase in the blockage level. In consideration of the decrease in the fuel gas accompanying the increase in the pressure, the pressure is increased to Nc calculated by the following equation. In step 3, the rotational speed Nc for this improved operation is
And proceeds to step 4. The air-fuel ratio maintenance coefficient Ku
p is the change in occlusion (that is, the change in the coefficient a ₃ of the cubic term)
When, by a factor determined by the change in the fuel gas amount in accordance with changes of the closure (that is, if, large blockage level) when a ₃ is small large small when a ₃ is large. Nc = Kup × Nd Expression Nd: Initially set rotation speed without blockage Nc: Speed for improvement operation Kup: Air-fuel ratio maintenance coefficient (> 1.0) Therefore, in the improvement operation, the coefficient a ₃ of the third order term is used. The rotation can be performed at the corresponding target rotation speed Nc.

In step 4, it is determined whether or not the calculated coefficient a _{3 of the} third order term is equal to or higher than the abnormal level aSTP (= 1.6 × 10 ^-9 , corresponding to the first level). Incidentally, blockage level higher this a ₃ is small is large. When it is determined that the coefficient a _{3 of the} third order is lower than the abnormal level aSTP, it is determined that the occlusion level is extremely large and the state is abnormal, and the process proceeds to step 9, where an error code “99” indicating the abnormality is displayed. Stop operation of the appliance immediately.

On the other hand, the coefficient a of the third order term_ThreeIs abnormal level aS
If it is determined that it is equal to or greater than TP, the coefficient a_ThreeBut
Capability restriction level aIPD (= 1.9 × 10^-9, 2nd level
(S5), and a_ThreeIs aIP
If it is determined to be D or less, the occlusion level is large,
Error code "10" warning that the supply / exhaust system seems to be blocked
Display and reduce the maximum input Ip to 65% of normal capacity
After performing the capacity-limited operation to limit the maximum combustion amount
(S6) In step 3, the coefficient a of the third order term _ThreeBased on
Operation to rotate the fan F at the calculated rotation speed Nc
Invert (S8) and return to step 1. In addition, this ability
Limited operation is performed when the blockage level increases to a predetermined level or higher.
Instead of immediately disabling the water heater,
Limit the amount of combustion to 65% and use a water heater for a while
I can do it. However, during the limited capacity operation,
Don't let the input drop further when you come to Step 6
And maintain 65%.

If it is determined in step 5 that a ₃ exceeds aIPD, the blockage level is not large enough to limit the maximum input, so that the normal operation is performed with the maximum input kept at 100%. It is determined whether or not this a ₃ is less than the improved operation level aRCV (= 2.3 × 10 ⁻⁹ ) (S7). If it is determined that a ₃ is less than aRCV, the blockage level is slightly larger, so in step 3 An improved operation of rotating the fan F at the calculated rotation speed Nc is performed (S8), and the process returns to step S1. On the other hand, a ₃ is aR
If it is determined to be CV or more, the blockage level is sufficiently small and there is no risk of blockage of the air supply / exhaust system. Thus, to determine the blockage level based on the coefficient a ₃ of the third-order terms, the normal operation, capacity limited operation, the abnormal stop performed in accordance with the magnitude.

Next, detection of a clogging level performed at the time of post-purge after stopping combustion will be described. When the hot water supply currant is closed during combustion and the flow rate sensor S2 detects a water stop state, the combustion control unit 9a of the controller 9 stops the combustion, sends a signal to the fan motor control unit 9c, and activates the fan F for a predetermined time. Rotate. In this post-purge, the result of step 1 is NO, and the fuel gas is shut off to extinguish the fire (S1
0), the number of rotations of the fan motor M is switched stepwise,
For each of the six rotation speeds 1 to N6, the rotation speed Nd and the current value Id are detected t2 seconds after the rotation speed is stabilized (S11).
→ S12 → S13 → S11). Then, the detected current value Id is voltage-corrected by the equation, and the voltage-corrected value Iv is temperature-corrected by the equation to calculate the current value Ic.

Then, the corrected current value Ic and the detected rotational speed Nd are substituted into a functional relational expression, and the coefficient of each order is obtained by the least square method. That is, a ₃ , a ₁ , a
₀ is calculated (S14). Furthermore, a ₃ , a calculated this time
₁ , a ₀ and the previously calculated a ₃ ′, a ₁ ′, a ₀ ′ are subjected to a smoothing calculation for weighting 1: 9, and coefficients a ₃ ″, a ₁ ″,
a ₀ "to calculate the (S15). For _{example, a 3" = (a 3} +
9a ₃ ′) / 10 The reason that the coefficient a ₃ calculated this time is not used as it is is to avoid malfunction of the water heater in response to a temporary phenomenon such as instantaneous application of wind pressure to the exhaust stack. That's why. In particular, since the coefficients a ₁ ″ and a ₀ ″ of the relational expression calculated by the post-purge are used in the expressions and the expressions, they are not sensitive to a temporary increase in the blockage level.

Next, in order to reflect the operation according to the blockage level in the next combustion operation, the smoothed coefficient a
₃ "is higher than or equal to the abnormal level aSTP (S1).
6). If it is determined that a ₃ ″ is less than aSTP, it is determined that the obstruction level is very large and abnormal, and the process proceeds to step 9, where an error code “99” indicating the abnormality is displayed and the operation of the appliance is started immediately. Stop.

On the other hand, when it is determined that the coefficient a ₃ ″ after the smoothing operation is equal to or higher than the abnormal level aSTP, it is determined whether the coefficient a ₃ ″ is equal to or lower than the capability limit level aIPD (S 1).
7) If it is determined that a ₃ ″ is equal to or less than aIPD, since the blockage level is large, the fact that the capacity-limited operation for limiting the maximum capacity to 65% at the start of the next operation is stored (S18).

In step 17, a ₃ ″ is aIPD
If the speed exceeds the limit, it is determined that there is no need to limit the maximum capacity because the blockage level is within the allowable range, and at the next operation start, the maximum input is set to 100% and the rotation speed according to the blockage level is increased. The relational expression is stored so as to perform the normal operation to be corrected (S19). Therefore, even if the capacity-restricted operation is performed during combustion, if the supply / exhaust system blockage status is normal upon detection of the post-purge, the blockage during combustion is determined to be sudden, and the next operation is normally started. Return to driving. However, during combustion, for the sake of safety, even if the blockage level is improved, the operation is not changed from the capacity-limited operation to the normal operation.

According to the water heater 1 described above, the rotational speed Nb corrected based on the calculation value from the detection of the blockage level is the limit rotational speed Nltd, as indicated by the solid line arrow in FIG.
In this case, that is, in step 5, the coefficient a ₃ of the third-order term is changed to the capability restriction level aIPD (= 1.9 × 1
0 ^-9 ) or less, it can be determined that the occlusion level is relatively high.
Is reduced to 65% of the normal capacity (Ipa in FIG. 3), and then the rotational speed correction control is started. Therefore, the control time from the detection of the blockage level to the start of the capacity limiting operation can be reduced as compared with the conventional type, and there is almost no control delay. As a result, the short supply period becomes extremely short, and incomplete combustion does not occur, which is safe.

The operating conditions are changed to the normal operation, the improved operation, the capacity-limited operation, and the operation status in accordance with the blockage level (here, the coefficient a ₃ ).
Since the operation is switched to the abnormal stop, combustion can be performed while maintaining a desired air-fuel ratio, and incomplete combustion can be prevented. In particular, when the vehicle is significantly blocked, do not perform improved operation or capacity-limited operation.
Since the operation of the device is stopped immediately after the blockage is detected, harmful gas due to incomplete combustion is hardly generated and the device is safe. In addition, since the detection data at a plurality of rotation speeds is used at the time of post-purge and the coefficient a ₃ ″ relating to the occlusion level is obtained by the least squares method, even if one of the detection values is a large value, the There is no malfunction due to.

Further, at the time of post-purge, since the coefficients a ₁ ″ and a ₀ ″ irrespective of the blockage level are calculated, the coefficient a ₃ can be easily calculated during combustion. In particular, since the rotation is performed during post-purge in which combustion is stopped, the number of rotations can be freely switched, and the calculation of the relational expression is easy.
In addition, since the blockage level is calculated by the relational expression, it is not necessary to forcibly set a specific rotation speed for detection of the blockage level during combustion, and the blockage level can be easily set even under various conditions. And it can detect with high accuracy.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention. is there. For example, it may be determined by using the detection value of the closing level instead of the calculated value a _3. When controlling the fan motor based on the blockage level, the applied voltage or current may be corrected instead of correcting the rotation speed.

[0037]

As described in detail above, claim 1 of the present invention
According to the described combustion apparatus, if the blockage level is between the first level of the severe level and the second level of the mild level, the control from the detection of the blockage level to the setting of the lowering of the upper limit of the combustion amount is controlled by the drive control amount of the fan. Since the correction is not interrupted, the air supply shortage period can be shortened. Further, since the improved operation of rotating the fan with the drive control amount according to the blockage level is performed, the combustion performance is improved. Further, when the blockage level is equal to or higher than the first severe level, the operation of the appliance is immediately stopped without performing the correction control, so that the combustion time when the supply / exhaust system is abnormal can be shortened, and the incomplete combustion can be quickly performed. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a blockage level detection process.

FIG. 2 is a schematic configuration diagram of a water heater of the present embodiment.

FIG. 3 is a graph of a rotation speed with respect to a performance.

[Explanation of symbols]

F: fan, M: fan motor, 2: heat exchanger, 9: controller, 9d: rotation correction unit, 9g: blockage level detection unit, 9i: load data detection unit, 9h: relational expression calculation unit, 1
3: Burner.

Continued on the front page F term (reference) 3K003 AB02 AB06 AC02 AC07 BB02 BC06 BC09 CA03 CA04 CA05 CB05 CC02 CC04 DA03 EA02 FB04 FC04 GA03 JA06 JA12 KA05 KB02 LA00 LA02 LA06 NA04 NA07

Claims (1)

[Claims] 1. A combustion amount adjusting means for adjusting a combustion amount of a burner, a fan for supplying an amount of combustion air corresponding to the combustion amount to the burner, and a blockage level detection for detecting a blockage level of a supply / exhaust passage. Means, and a fan motor control means for correcting the target drive control amount of the fan based on the blockage level from the blockage level detection means, wherein when correcting the fan, the blockage level is severe. If the level is equal to or higher than the first level, the operation of the appliance is immediately stopped without performing any correction. If the occlusion level is between the first level and the second level, the upper limit value of the combustion amount is determined. And combustion control means for performing correction control without lowering the upper limit of the combustion amount if the blockage level is equal to or less than the second light level. Burning Location.