JP2000240937A - Combustion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustor which is accurately detect air supply/exhaust resistance. SOLUTION: There are provided an air supply/exhaust resistance detection section 9g on a controller 9, and in the air supply/exhaust resistance detection section 9g there are provided a load data detection section 9i for detecting a current and voltage at revolutions by changing revolutions of a fan motor M and a relation equation calculation section 9h for calculating the current as a relation equation of the nth order function of revolutions. Accordingly, the air supply/exhaust resistance detection section 9g discriminates fan motor inherent resistance and air supply/exhaust resistance in terms of the relation equation, detects the air supply/exhaust resistance in terms of a coefficient of a term associated with the air intake/exhaust resistance, and a revolution correction section 9d corrects the revolutions of a fan F in response to the detected air intake/exhaust resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion device having a fan disposed in an air supply passage, and more particularly, to a combustion device which corrects the number of revolutions of the fan in accordance with air supply / exhaust resistance.

[0002]

2. Description of the Related Art In a combustion apparatus in which combustion air is sucked by a fan and burned, the air supply filter is clogged with dust, oil, etc., and the air supply / exhaust resistance is changed. It is not possible to maintain a predetermined air-fuel ratio only by controlling the rotation speed of the motor. For this reason, in this state, the amount of combustion air is insufficient and the combustion tends to be incomplete. In addition, soot may be generated, and fins of the heat exchanger may be clogged, resulting in poor exhaust. For this reason, the water heater detects the current value and the rotation speed of the fan motor, and if the current value when the fan is rotating at the predetermined rotation speed falls below the predetermined value, the supply / exhaust resistance increases. Increase the number of revolutions, stop,
In some cases, the number of revolutions is controlled so that the current value becomes a predetermined value.

[0003]

However, factors other than the air supply / exhaust resistance, for example, the resistance of the bearing or the grease applied to the fan motor change, and the current value of the fan motor fluctuates. And the accuracy of detecting the supply / exhaust resistance is reduced. Furthermore, the current value of the fan motor is constantly changing under various conditions, and even in a temporary unusual state,
If the speed is controlled by detecting the current value sensitively,
There have been problems such as a decrease in air volume, and conversely, an excessive amount and a misfire. Therefore, the combustion device of the present invention
It is an object of the present invention to solve the above-mentioned problem and accurately detect supply / exhaust resistance.

[0004]

According to a first aspect of the present invention, there is provided a combustion apparatus for supplying combustion air to a burner and controlling the number of revolutions of the fan according to the amount of fuel gas. In a combustion device provided with fan motor control means and supply / exhaust resistance detection means for detecting supply / exhaust resistance,
A load data detecting means for detecting a plurality of points of a fan motor current value and a voltage value for each of the rotation speeds by changing the rotation speed of the fan; Function (n = 2 or 3
Or 4) a relational expression calculating means for calculating as a relational expression, wherein the supply / exhaust resistance detecting means distinguishes fan motor specific resistance and supply / exhaust resistance by the term of the relational expression, The point is to detect the supply / exhaust resistance by the coefficient of.

According to a second aspect of the present invention, there is provided a combustion apparatus as set forth in the first aspect, wherein the supply / exhaust resistance detected by the supply / exhaust resistance detecting means is equal to or higher than a predetermined level. , Limit the upper limit of fuel gas amount,
Alternatively, the gist is to stop the combustion.

According to a third aspect of the present invention, there is provided a combustion apparatus as set forth in the first or second aspect, wherein the load data detection means, the relational expression calculation means, The gist of the invention is to make the above-mentioned supply / exhaust resistance detecting means work.

According to a fourth aspect of the present invention, there is provided a combustion apparatus according to the third aspect, wherein the supply / exhaust resistance detecting means includes a fuel gas amount and a combustion quantity at the time of combustion before post-purge. The gist is to correct the supply / exhaust resistance detected at the time of post-purge according to the product of time.

According to a fifth aspect of the present invention, there is provided a combustion apparatus according to the fifth aspect of the present invention, wherein the relational expression calculating means includes a fan motor based on a relational expression calculated during post-purge. The gist of the present invention is to store a coefficient relating to the resistance and calculate a relational expression using the stored coefficient relating to the fan motor specific resistance during the pre-purge or the combustion.

According to a sixth aspect of the present invention, there is provided a combustion apparatus according to the first to fifth aspects of the present invention, wherein the relational expression calculating means is provided between the points at which the rotational speed is higher than a predetermined level. The difference between the current values of
The gist is to calculate as a relational expression of the following function (n = 2 or 3 or 4).

According to a seventh aspect of the present invention, there is provided a combustion apparatus for correcting the number of rotations of a fan in accordance with the detected supply / exhaust resistance. The gist is to provide a correction means.

According to another aspect of the present invention, there is provided a combustion apparatus according to the present invention, wherein the rotational speed correction means stores a supply / exhaust resistance detected at the time of pre-purge or post-purge. Therefore, the gist of the present invention is to correct the rotation speed of the fan during combustion.

According to a ninth aspect of the present invention, there is provided a combustion apparatus as set forth in the seventh or eighth aspect of the present invention, wherein the rotation speed correction means adjusts the rotation speed of the fan according to the supply / exhaust resistance. The gist of the correction is to correct the rotation speed of the fan so as to keep the air-fuel ratio to the fuel gas constant, taking into account the fact that the fuel gas amount changes with the pressure change in the combustion chamber.

According to a tenth aspect of the present invention, which solves the above-mentioned problems, the combustion apparatus according to the first to ninth aspects further includes a temperature correction means for correcting the current value according to the supply air temperature. That is the gist.

In the combustion apparatus according to the first aspect of the present invention, the load data detecting means changes the rotation speed of the fan motor to a plurality of rotation speeds, and the current value and the voltage value of the fan motor with respect to the rotation speed. Is detected at a plurality of points, and the relational expression calculating means calculates the current value as a relational expression of the n-th order function of the rotation speed based on the value detected by the load data detecting means,
The supply / exhaust resistance detecting means distinguishes the fan motor specific resistance and the supply / exhaust resistance by the term of the relational expression, and detects the supply / exhaust resistance by the coefficient of the term related to the supply / exhaust resistance. Therefore, it is possible to accurately detect only the supply / exhaust resistance without the fan motor specific resistance.

[0015] The present invention having the above-described structure has a second aspect.
In the described combustion apparatus, the supply / exhaust resistance detection means limits the upper limit of the fuel gas amount or stops combustion when the detected supply / exhaust resistance is equal to or higher than a predetermined level. Therefore, when the air supply / exhaust resistance becomes equal to or higher than the predetermined level, the operation is not forcibly continued, so that the combustion device is not damaged.

Further, the present invention has the above-mentioned structure.
In the described combustion apparatus, the load data detecting means, the relational expression calculating means, and the supply / exhaust resistance detecting means operate during the post-purge. Therefore, during the post-purge, the rotation speed of the fan can be freely changed, so that the supply / exhaust resistance can be detected with high accuracy.

Further, the present invention has the above-mentioned structure.
In the combustion device described above, the supply / exhaust resistance detection means corrects the supply / exhaust resistance detected at the time of post-purge according to the product of the fuel gas amount and the combustion time at the time of combustion before post-purge. At the time of post-purging after the end of combustion, the supply air expands due to residual heat and the supply / exhaust resistance is increased.The supply / exhaust resistance detected at the time of post-purging is based on the fuel gas amount, combustion time and combustion time immediately before post-purging. Causes an error. For this reason, the supply / exhaust resistance detected at the time of post-purge is corrected according to the product of the fuel gas amount at the time of combustion and the combustion time. Therefore,
The accuracy of the supply / exhaust resistance detected at the time of post-purging can be improved.

Further, the present invention having the above-mentioned structure has a fifth aspect.
In the described combustion apparatus, when the relational expression calculating means calculates the current value as the relational expression of the number of revolutions during the pre-purge or the combustion, the coefficient relating to the fan motor specific resistance detected at the time of the post-purge is stored and used as it is. . Therefore, during the pre-purge or the combustion, the coefficient relating to the fan motor specific resistance detected at the time of the post-purge is stored and used as it is, so that the arithmetic processing of the relational expression can be facilitated.

Further, the present invention has the above-mentioned structure.
In the combustion apparatus described above, the relational expression calculating means determines a difference in current value between points at which the number of rotations is equal to or higher than a predetermined level by a relational expression of an nth order function (n = 2 or 3 or 4) of the number of rotations of the point. And Therefore, the relational expression becomes a simple expression because the fan motor specific resistance is canceled. For example, when the control method of the motor is PWM, the coefficient for obtaining the current value as the relational expression of the quartic function of the number of rotations is five. One. Therefore, the calculation of the relational expression becomes easy. Further, since the relational expression is obtained based on the detected value of the high rotation speed equal to or higher than the predetermined level, the load due to the fan motor specific resistance is smaller than the load due to the supply / exhaust resistance. The change in the value becomes small, and the supply / exhaust resistance can be detected accurately.

Further, the present invention has the above-mentioned structure.
The described combustion device corrects the rotation speed of the fan according to the detected supply / exhaust resistance detected by the rotation speed correction means. Therefore, when the air supply / exhaust resistance increases, the fan can be rotated with the rotation speed appropriately corrected in distinction from the fan motor specific resistance.

Further, the present invention has the above-mentioned structure.
In the described combustion apparatus, the rotation speed correction means stores the supply / exhaust resistance detected at the time of pre-purge or post-purge, and corrects the rotation speed of the fan during combustion. Therefore, the fan can be appropriately rotated before the start of combustion.

Further, the present invention has the above-mentioned structure.
In the combustion device described above, when the rotation speed correction means corrects the rotation speed of the fan in accordance with the supply / exhaust resistance, the air-fuel ratio with respect to the fuel gas is taken into account in consideration of the fact that the fuel gas amount changes with the pressure change in the combustion chamber. Is corrected so that is constant. Therefore, when the air supply / exhaust resistance changes, the rotation speed of the fan can be corrected while keeping the combustion state optimal.

Further, the present invention having the above-mentioned structure has a first aspect.
0, the temperature correcting means corrects the current value according to the supply air temperature. That is, if the supply air temperature is high, the supply air expands and the supply / exhaust resistance increases, so the current value of the fan motor detected by the temperature correction means is corrected according to the supply air temperature. Therefore, the supply / exhaust resistance can be detected with higher accuracy.

[0024]

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 water heater of the present invention will be described below. FIG. 1 is a schematic diagram of a water heater 1 as one embodiment. The water heater 1 includes a fan F for feeding combustion air into the combustion chamber 3, a burner 13 for burning fuel gas, a heat exchanger 2 for heating water in the water passage with the combustion flame of the burner, and a heat exchanger 2 and a burner. A combustion chamber 3 that forms a combustion space between the combustion chambers 13 is provided.

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

In the gas passage 10 to the burner 13,
An original solenoid valve MV1 for opening and closing the flow path from the upstream side, a proportional solenoid valve MV2 for controlling the fuel gas amount, and a main solenoid valve MV3 are provided. Further, the burner 13 has an electrode 12 for igniting a gas by continuous discharge, and a flame rod 1 for detecting a combustion flame.
1 is provided. These are electrically connected to the controller 9 to perform predetermined control such as ignition, tapping and stopping.

The fan F arranged at the bottom of the combustion chamber 3
The sirocco fan is driven by a DC brushless motor, and the number of rotations of the fan motor M is controlled to supply combustion air in an amount corresponding to the amount of fuel gas to the combustion chamber 3. An air supply temperature sensor S4 for detecting an air supply temperature Tz is provided at an air supply port of the fan F.

The controller 9 includes a microcomputer having a CPU, a RAM, and a ROM constituting a well-known arithmetic logic operation circuit (not shown), an input interface for inputting signals from various sensors, and various actuators such as a fan motor M. It comprises an output interface for outputting a drive signal and the like. A remote controller (not shown) for remote operation is connected to the controller 9. The remote controller includes an operation switch, a tap water temperature setting unit, and an alarm lamp (an alarm buzzer for notifying an abnormality in supply / exhaust resistance). May be provided).

The controller 9 is mainly composed of a microcomputer. When focusing on its function, the controller 9 detects the fuel gas amount of the burner 13 from the hot water temperature, the incoming water temperature, and the flow rate so that the target hot water temperature is attained. Hot water supply controller 9a for controlling combustion
A fan motor control unit 9c for controlling the rotation speed of the fan F based on a signal from the hot water supply control unit 9a to supply combustion air in accordance with the amount of fuel gas; and a supply / exhaust resistance detection unit 9g for detecting supply / exhaust resistance. And an abnormality processing unit 9p that issues an alarm and stops combustion when the detected supply / exhaust resistance is equal to or higher than a predetermined level. The load / exhaust resistance detecting section 9g has a load data detecting section 9i for detecting load data (motor current, motor voltage, rotation speed) by the fan motor M.
And a relational expression calculating unit 9h for calculating a relational expression described later from the detected load data. The load data detection unit 9i includes a rotation speed detection unit 9 that detects the rotation speed of the fan motor M based on the rotation pulse from the fan motor M.
j, a motor current detector 9k for detecting a motor current of the fan motor M, and a motor voltage detector 9n for detecting a voltage applied to the fan motor M. The motor current detector 9k includes a motor voltage A voltage / temperature corrector 9m for correcting the motor current based on the applied voltage detected by the detector 9n and the supply air temperature Tz detected by the supply air temperature sensor S4 is provided. Further, the fan motor control unit 9c described above is provided with a rotation speed correction unit 9d for correcting the fan rotation speed based on the detection result by the supply / exhaust resistance detection unit 9g, and the hot water supply control unit 9a includes a supply / exhaust resistance detection unit. When the supply / exhaust resistance detected by the 9g increases excessively, the water heater 1
Is limited to 65% of the maximum capacity.

Next, the supply / exhaust resistance detecting section 9g of the controller 9 will be described. The supply / exhaust resistance detection unit 9g
A relational expression is calculated from the detected rotational speed, motor current, and load data of the motor voltage, and the detection result is transmitted to the abnormality processing unit 9p and the capacity limiting unit 9b according to the level of the supply / exhaust resistance detected from the relational expression. .

Here, the relational expression used in the present embodiment and the coefficient relating to the supply / exhaust resistance of the relational expression will be described in more detail. In general, it is known that the following relational expression holds for a fan motor.

(Equation 1)

In the equation, BN + I ₀ ′ is the energy consumed inside the fan motor M, which is the resistance of the bearing of the fan rotating shaft or the resistance of grease, and varies depending on environmental conditions. On the other hand, the pressure coefficient α and the fan efficiency η of the sirocco fan are almost constant in the range of the actual number of rotations, and the torque constant Kt does not change at a constant temperature. Therefore,
Only the flow coefficient β changes according to the change in the air volume, and the flow coefficient β can be said to be a coefficient relating to the supply / exhaust resistance. Therefore, the following equation is obtained by rewriting the equation for easy understanding.

(Equation 2) Thus, the motor current I is in the quadratic function relationship between the rotational speed N, it is possible to detect the supply and exhaust resistance from a change in the coefficient of formula A, the motor current I ₀ is the coefficient B and the internal consumption of the internal consumption ' From this change, the change in the fan motor specific resistance can be detected. That is, from the load data of the motor current I and the rotation speed N at a plurality of points of the rotation speed,
An equation is calculated by the least squares method, and the supply / exhaust resistance is detected from the coefficient A of the quadratic term of the equation.
₀ ′, the fan motor specific resistance can be detected.

However, since the motor current I differs depending on the motor control method, the quadratic function relationship of the equation is satisfied only when the motor control method is the pulse amplitude modulation control method (PA
M: Pulse-Amplitude-Modulation). Pulse width modulation control method (PWM: Pulse Width Modulation)
In this case, the motor current has a quartic function relation of the number of rotations, and the following relational expression holds.

(Equation 3) In the case of PWM, since the fourth-order term is a very small value, the third-order function relation of the following equation may be established without the fourth-order term of the equation.

(Equation 4)

The fact that the supply / exhaust resistance and the fan motor specific resistance can be detected separately from such a relational expression will be described based on experimental data. FIG. 4 is a graph in which the relationship between the number of revolutions and the motor current is measured experimentally (however,
The motor control method is PAM), the same type of motor F
1 and the motor F2, the number of rotations measured by taking out the sirocco fan from the water heater 1 with the sirocco fan incorporated in the motor,
The current characteristics and the number-of-rotations-current characteristics measured with the motor alone with the sirocco fan removed are shown. In the figure, the motor F
1 and the motor F2 have a difference of 60 mA (= 457-397) at 3000 rotations with the sirocco fan incorporated. Further, comparing the rotation speed-current characteristics of each motor alone, the motor currents of the motor F1 and the motor F2 are different. This indicates that the motor specific resistance differs between the motor F1 and the motor F2. As described above, since the motor current is different when the motor specific resistance is different, it can be seen that the supply / exhaust resistance cannot be accurately detected from the motor current alone. On the other hand, it is known that the motor current has a quadratic function relationship of the number of rotations as shown in the equation when the control method of the motor is PAM control.
The supply / exhaust resistance has a functional relationship with the secondary term, and the fan motor specific resistance has a functional relationship with the primary term. Therefore, when the relational expression (Table 1) of the quadratic function of the rotation speed with respect to the current value is obtained from the data of the rotation speed and the motor current (the data in FIG. 4) by the least square method, the motor F1 and the motor F2 are compared. The coefficient of the first-order term of the relational expression is different, whereas the coefficient of the second-order term is 3.20, which is almost the same.

[Table 1] That is, from the relational expression, it can be read that the supply and exhaust resistances of the motor F1 and the motor F2 are the same and the fan motor specific resistances are different. Therefore, the supply / exhaust resistance and the fan motor specific resistance can be detected separately from the coefficient of the term of the relational expression.

FIG. 5 and Table 2 show a case where the same motor compares the motor current at the initial stage of rotation with the motor current after one hour of idling (with no sirocco fan incorporated). As can be seen from the figure, the motor current changes before and after idling due to fluctuations in the fan motor specific resistance.

[Table 2] This indicates that even for the same fan motor M, the air supply / exhaust resistance cannot be accurately detected unless the air supply / exhaust resistance and the fan motor specific resistance are distinguished.

Further, in FIG. 6, the same fan motor M
Shows the rotation speed-current characteristics when the supply and exhaust resistances are different. When the relational expression of the quadratic function of the rotation speed with respect to the current value is obtained from the data, the relational expression of Table 3 is calculated. The coefficient of the secondary term is increased from 3.278 to 2. It can be seen that it has become smaller at 457. (The coefficient relating to the supply / exhaust resistance is small when the supply / exhaust resistance is large, and large when the supply / exhaust resistance is small.)

[Table 3] Therefore, it can be seen that by monitoring the coefficient of the quadratic term, an increase in the supply / exhaust resistance can be accurately detected.

Next, the controller 9 in the present embodiment
The following describes the supply / exhaust resistance detection processing executed by the supply / exhaust resistance detection unit 9g of the first embodiment (in the following embodiments, the control method of the motor is PWM). In the combustion apparatus according to the present embodiment, the detection processing of the supply / exhaust resistance is performed in three stages during pre-purge, during combustion, and during post-purge before combustion is started.
First, the supply / exhaust resistance detection routine A during pre-purge and during combustion before the start of combustion will be described with reference to the flowchart shown in FIG. When the operation switch of the remote controller is turned on, the hot water supply curn is opened, and the flow rate sensor S2 detects the water passing state, the hot water supply control unit 9a of the controller 9 instructs the fan motor control unit 9c to rotate the fan F, Before the combustion, a pre-purge for discharging the combustion exhaust gas remaining in the combustion chamber 3 is performed. The fan motor control section 9c starts the pre-purge by rotating the fan motor M, and at the same time, the supply / exhaust resistance detection section 9g starts the supply / exhaust resistance detection routine A. First, at t1 seconds after the rotation of the fan motor M is stabilized (S1), the rotation speed detection unit 9j detects the rotation speed Np of the fan motor M, and the motor current detection unit 9k detects the motor current I
Then, the motor voltage detector 9n detects the motor voltage Vp (S2). Next, the voltage / temperature correction unit 9m converts the current value Ip into a current value Ic at the time of the reference voltage Vs according to the following equation (hereinafter, referred to as voltage correction).

(Equation 5)

Further, since the air density changes according to the supply air temperature Tz and the load of the motor changes, the voltage / temperature correction unit 9
m corrects the current value Ic by the following equation and corrects the current value Ic ′.
(Hereinafter, referred to as temperature correction).

(Equation 6)

[0039] Subsequently, on the basis of data relation calculator 9h is due to load data detector 9i, obtains the coefficient a ₃ of the third order terms of the supply and exhaust resistance by the following equation obtained by modifying the formula (S
3).

(Equation 7) In this case, second-order non-coefficient _{a 3} of the third order terms, primary,
As the coefficient of the zero-order term, the coefficients a ₀ ′, a ₁ ′, and a ₂ ′ calculated during the previous post-purge are used as they are, as described later. This is because the calculation time of the air supply / exhaust resistance is shortened, and even if it is used as it is, there is no significant influence on the calculation of the air supply / exhaust resistance.

[0040] Then, the supply and exhaust resistance detection unit 9g judges coefficient _{a 3} calculated for whether or not a predetermined value _{a PRE} above (S4). If it is less than the predetermined value a _PRE , it is determined that the supply / exhaust resistance is too large, and the prepurge is started again (S5). In addition, if the predetermined value _aPRE does not become equal to or more than the predetermined value, a signal is sent to the abnormality processing unit 9p to abnormally stop the water heater 1 (S6).

[0041] When the coefficient a ₃ is higher than the predetermined value a _PRE, it is determined that the supply and exhaust resistance is within the allowable, a signal is sent to the hot-water supply control section 9a, the hot water supply control section 9a, the original solenoid valve MV
1. The main solenoid valve MV3 is opened, and the electrode 1 of the burner 13 is opened.
2, a continuous discharge is started, the fuel gas is ignited and combustion is started (S7), and the proportional solenoid valve MV2 is controlled so that the tapping temperature becomes the target tapping temperature to control the fuel gas amount.

[0042] Then, the supply and exhaust resistance detection unit 9g the combustion is initiated fan rotational speed N _m reaches or exceeds a predetermined rotational speed N ₆ (S8), it is stable to rotation than 2 seconds check out (S9), the load data detector 9i is the rotational speed is changed to several steps in a range not affecting the combustion (± 100~150rpm) each rotational speed _{N m,} the current value _{I m,} the voltage value V _m is detected (S10). Then, in the same manner as in the pre-purge, the voltage-temperature correction unit 9m corrects the current value I _m by the voltage and temperature, obtaining the third order coefficient a ₃ of the supply and exhaust resistance by equation (S11). In this case, the coefficients a ₀ ′, a ₁ ′, and a ₂ ′ calculated at the time of post-purging are used as they are as the second-order, first-order, and zero-order coefficients other than the third-order coefficient a ₃ .

[0043] Then, the supply and exhaust resistance detection unit 9g the coefficients _{a 3} calculated determines whether less than a predetermined value _{a RCV} (S12). If the value exceeds the predetermined value a _RCV , the air supply / exhaust resistance is within the allowable range, and the flow returns to step 8 to repeat the same processing. If it is equal to or smaller than the predetermined value a _RCV , it is determined that the air supply / exhaust resistance is too large, and a signal is sent to the rotation speed correction unit 9d to perform an improved operation corresponding to an increase in the air supply / exhaust resistance.
This improves operation, in order to prevent from becoming incomplete combustion due to a decrease in air volume due to an increase of the supply and exhaust resistance, the rotational speed N _m of the fan motor M, so that the air-fuel ratio becomes constant, which will be described later combustion chamber In consideration of the decrease in the fuel gas accompanying the increase in the pressure, the rotation speed is increased to the rotation speed N _m 'calculated by the following equation (S13). The air-fuel ratio maintenance coefficient K _up is a coefficient determined by a change in the supply / exhaust resistance and a change in the fuel gas amount accompanying the change in the supply / exhaust resistance.

(Equation 8)

Next, the improved operation will be described in more detail. FIG. 7 shows a PQ characteristic, which is a relationship between a wind pressure and a flow rate of the fan F. Now, if the air supply / exhaust resistance increases when the fan is rotating at point "A",
Since the air volume decreases to the point "B", the fuel gas amount becomes excessive and incomplete combustion occurs. Therefore, when the supply / exhaust resistance increases, the fan speed is increased to increase the air volume. In this case, when you try to ensure the original air volume increased from N _m to N _{m "the} number of revolutions to the" two "points, the combustion flame is rather a air volume excess becomes lifting trend. This is a burner In spite of the fact that the pressure of the fuel gas ejected from the nozzle remains unchanged, the pressure in the combustion chamber 3 increases with an increase in the number of revolutions of the fan, and on the contrary, the amount of fuel gas decreases. when the air supply and exhaust resistance is increased, the rotational speed N _m rather than returning to the original air volume by increasing the rotational speed as the air-fuel ratio is constant N
_m ′. For example, while burning at the "A" point,
When the air supply and exhaust resistance rises and the air volume falls to the "B" point,
The rotational speed N _m → N _{m "Rather} than undo the air volume increases, since the amount of fuel gas with increasing fan pressure is reduced, it is reduced by the amount corresponding to a small air volume of the fuel gas amount" Ha The rotation speed is calculated from the equation N _m →
N _m '.

Further, in step 14, the ability restriction described later is performed.
It is determined whether or not the vehicle is driving, and
Is the rotational speed N increased by the improved operation._m′ Is the specified time
Number of turns N ₇Is determined. Revolution N_m'Is the place
Constant rotation speed N₇If smaller, step
8, the same processing is repeated. Increased by improved driving
Added rotation speed N_m'Is a predetermined rotation speed N₇Over
(S15) limits upper limit of fuel gas amount to 65% of initial value
Then, the operation is started and the process returns to step S8. (S1
6). In this capacity-limited operation, the supply and exhaust resistance is
If the water supply increases more than
Instead of limiting the maximum fuel gas volume to 65%
Line to be able to use the water heater for a while
U. If it is determined in step 14 that the vehicle is already in the limited capacity operation,
(S14), increased rotation speed N_m'Is a predetermined rotation speed N₈
Is determined (S17), and a predetermined rotational speed N is determined. ₈
In the following cases, the process returns to step 8 and the predetermined rotational speed N₈To
If it exceeds, the supply / exhaust resistance increases and the increase in the number of revolutions reaches the limit.
When it is determined that the temperature has reached, the abnormality processing unit 9p abnormally stops the water heater 1
Stop (S18). Thus, in improved operation,
When the resistance increases, the rotational speed N_m′ To increase the fuel gas
Do reducing the amount. The rotation speed N₈Is the rotation speed
N₇Set to a larger value, for example, the exhaust resistance
In the state, the supply of No. 16 whose rotation speed is about 3500 rpm
In the water heater, the rotation speed N ₇Is 5000 rpm, rotation speed N₈But
It is set to 5500 rpm. In addition, improved operation is combustion
Cleared by stop signal.

The target hot water temperature is changed by the remote controller,
If you change the amount of hot water by changing the opening of the hot water supply curan,
The fan motor control unit 9c controls the fan F according to the amount of fuel gas.
And the rotation speed corrector 9d appropriately corrects the rotation speed based on the stored air supply / exhaust resistance.

Next, detection of supply / exhaust resistance performed at the time of post-purge after stopping combustion will be described with reference to a flowchart shown in FIG. When the hot water supply currant is closed during the combustion and the flow rate sensor S2 detects the water stop state, the hot water supply control unit 9a of the controller 9 stops the combustion and the fan motor control unit 9
c, a post-purge is performed to maintain the rotation state of the fan F for a predetermined time. When entering the post-purge, the supply / exhaust resistance detection section 9g of the controller 9
The supply / exhaust resistance detection routine B is started. First, switch the rotational speed of the fan motor M gradually, to the rotation speed every 5 points of N ₁ to N _5, after t2 seconds rotational speed is stabilized, the rotation speed Np, the current value Ip, the voltage value Vp Detect (S31 → S32 → S33 → S31). Then, the detected current value is subjected to voltage correction using an equation, and temperature correction is performed using an equation.

Then, the rotational speed Np and the current value Ip are substituted into a functional relational expression, and a relational expression is obtained by the least square method. Furthermore, the coefficient a ₃ of the third order terms by the equation, the coefficient a ₃ performs smoothing calculation out with coefficient a _{3 "the} previously computed '
Is obtained (S34). Reason for not using the coefficient a ₃ calculated this time as it is, for example, in order to avoid the temporary phenomenon temporarily wind pressure in the exhaust pipe according to sensitively react combustion apparatus resulting in malfunction. In particular, since the coefficient of the relational expression calculated by the post-purge serves as a reference for the detection of the supply / exhaust resistance during pre-purge and combustion, the coefficient is not sensitive to a temporary increase in supply / exhaust resistance. Similarly, the coefficients a ₂ of the second-order, first-order, and zero-order terms of the calculated relational expression,
a ₁ , a ₀ are smoothed and coefficients a ₂ ′, a ₁ ′, a ₀ ′ are calculated.
Ask for.

Next, at step 35, the supply / exhaust resistance detecting section 9g determines whether or not the coefficient a ₃ ′ of the third order term relating to the supply / exhaust resistance is equal to or _smaller than a predetermined value a _STP . Predetermined value a _STP
If it is less than, it is determined that the supply / exhaust resistance is too large,
A signal is sent to the abnormality processing unit 9p to abnormally stop (S3
At the same time as 6), do not start the next operation. If the value is equal to or more than the predetermined value a _STP , it is further determined whether the value is less than the predetermined value a _IPD (S37). If the value is less than the predetermined value a _IPD , a signal is sent to the capacity limiting unit 9b to limit the maximum capacity at the start of the next operation, and a signal is sent to the rotation speed correcting unit 9d to improve the rotation speed. Remember to do. (S38). If it exceeds the predetermined value a _IPD , it is determined that the supply / exhaust resistance is within the allowable range, and the rotation speed correction unit 9d
And a relational expression is stored so that at the start of the next operation, the normal operation for correcting the rotation speed according to the supply / exhaust resistance is performed (S39).

As described above, according to the combustion apparatus of the present embodiment, since the fan motor specific resistance is distinguished from the supply / exhaust resistance, the supply / exhaust resistance can be accurately detected. Further, since the relational expression relating to the supply / exhaust resistance is obtained by using the detection data at a plurality of rotation speeds and the least squares method, even if one of the detection values is a large value, a malfunction may occur. do not do. In addition, since the supply / exhaust resistance is calculated by the relational expression, it is not necessary to forcibly set a specific rotation speed during combustion in order to detect the supply / exhaust resistance. Can be easily and accurately detected. At the time of post-purge, the coefficients a ₂ ′ and a ₂ ′ of the coefficients
_{1 ',} a _0' for previously obtained only facilitates the detection of the supply and exhaust resistance of and during prepurge combustion. In particular,
During the post-purge, the relational expression can be easily obtained by freely switching the rotation speed. Further, even during combustion, since the supply / exhaust resistance is detected from the relational expression every moment, even if the condition such as the fuel gas amount changes, the fan can be immediately rotated at an appropriate rotation speed.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments at all, and it is needless to say that the present invention can be carried out in various modes without departing from the gist of the present invention. It is. For example, in the present embodiment, the motor control method is pulse width modulation (PW
In the case of M), the relational expression is a relational expression of a cubic function of the rotation speed, and the supply / exhaust resistance is calculated by the coefficient of the cubic term. The supply / exhaust resistance may be calculated by the following coefficient.

Further, in order to more accurately detect the supply / exhaust resistance at the time of post-purging after the end of combustion, the supply / exhaust resistance detected at the time of post-purging is temperature-corrected in accordance with the product of the fuel gas amount and the combustion time during the immediately preceding combustion. You may. This is because the air supply / exhaust resistance changes depending on the air supply temperature, and when the air expands, the oxygen concentration substantially decreases, and as the air supply temperature increases, the air supply needs to be increased and the air supply / exhaust resistance increases. Because it becomes. The supply air temperature Tz, which is the outside air temperature, is detected by the supply air temperature sensor S4 upstream of the fan F, but the supply air temperature T downstream of the fan F differs depending on the combustion condition performed immediately before. For example, as shown in FIG. 8, the supply air temperature T downstream of the fan F gradually increases immediately after the start of combustion to reach a substantially constant temperature T ₀ , and the time t at which the temperature T reaches the constant temperature T ₀ varies depending on the fuel gas amount. On the other hand, the fuel gas amount Ip and the constant temperature T ₀
Is substantially constant even if the fuel gas amount is different. That is, the supply air temperature T downstream of the fan F, which is increased by the combustion heat, is related to the fuel gas amount Ip and the combustion time t. Thus, for example, in the case of PWM may be determined coefficients A ₃ according to the supply and exhaust resistance by correcting the supply air temperature coefficients a _{3 'according} to the supply and exhaust resistance by the following formula and (10), feed The detection accuracy of the exhaust resistance can be improved. However, after a predetermined time has elapsed, the supply air temperature T of the fan F downstream constant temperature T _0.

(Equation 9)

(Equation 10)

The rotation speed correction unit 9d of the controller 9
Alternatively, the rotational speed at the start of operation may be corrected in accordance with the supply / exhaust resistance detected at the time of post-purge, or the rotational speed at the start of combustion may be corrected by the supply / exhaust resistance detected at the time of pre-purge.

The relational expression calculating section 9h of the controller 9
May determine the difference between the current values at each rotation speed as a relational expression of the n-th order function of the rotation speed based on the high rotation speed detection value equal to or higher than a predetermined level. In particular, in the case of a relational expression of a quartic function such as PWM, the number of coefficients to be obtained becomes five and the calculation becomes complicated. For this reason, a relational expression is obtained from the expression as shown below so as to cancel out and eliminate the load corresponding to the fan motor specific resistance, and the coefficients A 'and B' relating to the supply / exhaust resistance are obtained from the simplified expression. May be.

[Equation 11] In this relational expression, by making the difference between the current values into the relational expression of the rotation speed, the coefficient C ′ relating to the fan motor specific resistance,
Of D 'and E', E 'is canceled out, and the terms C' and D 'are negligibly small. Therefore, the supply / exhaust resistance can be determined from the calculated coefficients A 'and B' of the simplified formula.
(Since the coefficient A 'relating to the supply / exhaust resistance is also small, the coefficient A' may be ignored and the supply / exhaust resistance may be determined only by the coefficient B '). Thus, when the relational expression is obtained from the difference between the current values,
Since the relational expression is simplified, the calculation becomes easy, and the air supply / exhaust resistance can be easily detected. In this case, the fan motor specific resistance becomes smaller as the rotation speed increases, and the ratio of the fan motor specific resistance to the entire current value decreases. As a result, the detection accuracy of the supply / exhaust resistance can be further increased.

[0055]

As described in detail above, the combustion apparatus according to the first aspect of the present invention can detect only the supply / exhaust resistance without the influence of the fan motor specific resistance. An excellent effect that detection can be performed with high accuracy is achieved.

Further, in the combustion apparatus according to the second aspect of the present invention, when the supply / exhaust resistance rises to a predetermined level or more, the maximum capacity is limited or the combustion is stopped, so that the safety is improved.

In the combustion apparatus according to the third aspect of the present invention, the detection of the supply / exhaust resistance is performed during the post-purge, so that the supply / exhaust resistance can be accurately detected.

Further, in the combustion apparatus according to the fourth aspect of the present invention, the supply / exhaust resistance detected at the time of post-purge is corrected in accordance with the product of the fuel gas amount at the time of combustion before the post-purge and the combustion time. The accuracy of the sometimes detected supply / exhaust resistance can be increased.

In the combustion apparatus according to the fifth aspect of the present invention, during pre-purge or combustion, the coefficient relating to the fan motor specific resistance detected at the time of post-purge is stored and used as it is. Easy.

Further, in the combustion apparatus according to the sixth aspect of the present invention, since the supply / exhaust resistance is detected from the relational expression for canceling the fan motor specific resistance, the supply / exhaust resistance can be easily detected.

Further, in the combustion apparatus according to the present invention, when the supply / exhaust resistance increases, the rotation speed of the fan can be appropriately corrected in distinction from the fan motor specific resistance, and normal combustion can be maintained. .

Further, the combustion apparatus according to claim 8 of the present invention can rotate the fan at an appropriate speed during combustion.

Further, in the combustion apparatus according to the ninth aspect of the present invention, when the supply / exhaust resistance changes, the rotation speed of the fan is corrected while maintaining the combustion state optimal even if the pressure in the combustion chamber changes. it can.

In the combustion apparatus according to the tenth aspect of the present invention, since the supply / exhaust resistance that changes according to the supply air temperature is corrected, the supply / exhaust resistance can be detected with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a combustion device as one embodiment.

FIG. 2 is a flowchart illustrating a supply / exhaust resistance detection routine A.

FIG. 3 is a flowchart illustrating a supply / exhaust resistance detection routine B;

FIG. 4 is a graph comparing motors F1 and B in an experiment.

FIG. 5 is a graph comparing experimentally before and after idling.

FIG. 6 is a graph comparing experimentally when the supply / exhaust resistance is different.

FIG. 7 is a graph showing a relationship between PQ characteristics of a fan and air supply / exhaust resistance.

FIG. 8 is a graph showing a relationship between supply air temperature T and combustion time t.

[Explanation of symbols]

 Fan F Fan motor M Heat exchanger 2 Combustion chamber 3 Water supply path 5 Hot water supply path 6 Controller 9 Supply / exhaust resistance detection section 9g Load data detection section 9i Relational expression calculation section 9h Rotation speed correction section 9d Gas flow path 10 Burner 13

Claims (10)

[Claims] 1. A fan for supplying combustion air to a burner, fan motor control means for controlling the number of revolutions of the fan in accordance with the amount of fuel gas, and supply / exhaust resistance detection means for detecting supply / exhaust resistance. In the combustion device, load data detecting means for changing the number of rotations of the fan to detect a plurality of points of the current value and voltage value of the fan motor for each number of rotations, and rotating the current value by the detected value of the load data detecting means. A relational expression calculating means for calculating as a relational expression of an n-th order function (n = 2 or 3 or 4) of the number, wherein the supply / exhaust resistance detecting means comprises: A combustion apparatus characterized by detecting supply / exhaust resistance by a coefficient of a term relating to supply / exhaust resistance. 2. The fuel supply system according to claim 1, wherein when the supply / exhaust resistance detected by the supply / exhaust resistance detection means is equal to or higher than a predetermined level, the upper limit of the fuel gas amount is limited or the combustion is stopped. Combustion equipment. 3. The combustion apparatus according to claim 1, wherein the load data detecting means, the relational expression calculating means, and the supply / exhaust resistance detecting means are operated during post-purge. 4. The air supply / exhaust resistance detection means corrects the air supply / exhaust resistance detected at the time of post-purge according to the product of the fuel gas amount and the combustion time at the time of combustion before post-purge. 3. The combustion device according to 3. 5. A coefficient relating to a fan motor specific resistance is stored from a relational expression calculated by the relational expression calculating means during post-purge, and the stored coefficient relating to the fan motor specific resistance is used during pre-purge or combustion. 5. The combustion device according to claim 3, wherein a relational expression is calculated. 6. The relational expression calculating means calculates a difference between current values between points having a high rotational speed equal to or higher than a predetermined level by a relation of an n-order function (n = 2 or 3 or 4) of the rotational speed of the point. The combustion device according to claim 1, wherein the value is calculated as an equation. 7. The combustion apparatus according to claim 1, further comprising a rotation speed correction means for correcting the rotation speed of the fan according to the detected supply / exhaust resistance. 8. The combustion apparatus according to claim 7, wherein the rotation speed correction means stores the supply / exhaust resistance detected at the time of pre-purge or post-purge and corrects the rotation speed of the fan during combustion. 9. The rotation speed correction means, when correcting the rotation speed of the fan according to the supply / exhaust resistance, taking into account that the fuel gas amount changes with a change in the pressure in the combustion chamber,
9. The combustion apparatus according to claim 7, wherein the rotation speed of the fan is corrected so that the air-fuel ratio with respect to the fuel gas is constant. 10. The combustion apparatus according to claim 1, further comprising a temperature correction unit that corrects the current value according to a supply air temperature.