JP3329919B2 - Fan control method and device for forced blast combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for controlling a fan of a forced blast type combustion apparatus in which combustion air is forcibly supplied by a fan and mixed with a fuel such as gas or petroleum for combustion.

[0002]

2. Description of the Related Art A so-called forced blast type combustion apparatus in which air is forcibly blown by a fan to burn it and exhaust gas is discharged from an exhaust port to the outside is widely used for gas and oil burning equipment such as a water heater. Have been. In this forced air combustion device, if the supply and exhaust air is obstructed by the reverse wind that enters from the exhaust port, troubles such as incomplete combustion or, in the worst case, the combustion flame being blown out by the reverse wind will occur. Occurred.

In order to solve these troubles, in the conventional forced air combustion apparatus, when the driving current is kept constant, the load on the fan motor is reduced by the back wind, and the number of rotations of the fan is reduced by the characteristics of the motor. By controlling the fan motor drive current to a predetermined constant value corresponding to the gas supply amount, the rotation speed of the fan motor is automatically increased at the time of a headwind, and the supply air amount is kept constant. And so on. According to this control method, the number of revolutions of the fan motor automatically increases at the time of a headwind, so that the supply / exhaust air amount is maintained constant,
Stable combustion can be ensured.

[0004]

However, when the drive current of the fan motor is controlled to be maintained at a predetermined constant value corresponding to the gas supply amount as in the prior art, even if the drive current is the same, the difference in the ambient temperature is not guaranteed. Therefore, there is a problem that the rotation speed of the fan motor is different. For example, when the temperature at 5 ° C. is compared with that at 40 ° C., the rotation speed at 40 ° C. is higher by about 15 to 20% than at 5 ° C. Further, even if the ambient temperature is the same, there is a problem that the characteristics are different for each fan motor, and the number of revolutions for the same drive current is different for each fan motor.

Therefore, even if the drive current of the fan motor is preset to a predetermined value corresponding to the gas supply amount, the rotation of the fan motor with respect to the same drive current depends on the change of the ambient temperature and the difference of the characteristics of each fan motor. The numbers differ, and the supply air amount becomes excessive or deficient, and there occurs a problem that combustion at an optimum mixing ratio is not performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to change the ambient temperature, the characteristics of individual fan motors, and the occurrence of headwinds. However, it is an object of the present invention to provide a method of controlling a fan of a forced blast combustion device capable of maintaining combustion at an optimum mixing ratio.

[0007]

In order to solve the above-mentioned problems, a fan control method according to the present invention has a function corresponding to a supply gas amount.
Drives the fan motor with the reference rotation speed set as the rotation speed
Then, the drive current of the fan motor when the rotation speed of the fan motor matches the set rotation speed is detected and stored as a reference current value for optimal combustion air supply .

When the supply gas amount changes,
The reference speed corresponding to the supply gas amount before the change and the change
Calculate the error from the actual rotation speed before the change and calculate the error based on the error.
To correct the reference speed corresponding to the changed supply gas amount.
In addition, the rotational speed after the correction is changed with respect to the supply gas amount after the change.
As a new set rotation speed, the rotation speed of the fan motor is
Drive the fan motor when it matches the new set speed.
Dynamic current is detected as the reference current value for optimal combustion air supply.
Outgoing update memory. Then, the reference current value is stored.
Thereafter, the drive current of the fan motor matches the reference current value.
It is characterized in that it is controlled so that:

Further, the first fan control device of the present invention comprises a drive current control means for controlling a drive current of the fan motor, a rotation number detection means for detecting a rotation number of the fan motor, and a drive current flowing through the fan motor. Drive current detecting means for detecting the rotation speed of the fan motor, based on the rotation speed detection signal of the rotation speed detection means and the detected drive current signal of the drive current detection means, the rotation speed of the fan motor to the set rotation speed corresponding to the supply gas amount Combustion control means for detecting and storing the drive current at the time of coincidence as a reference current value of the drive current corresponding to the supply gas amount at that time, and sending a voltage setting signal for giving the reference current value to the drive current control means, The drive current control means compares a voltage setting signal provided from the combustion control means with a drive voltage applied to the fan motor, thereby reducing a drive voltage of the fan motor. And controls to match the serial voltage setting signal.

[0010] The second fan control device of the present invention includes:
Drive current control means for controlling the drive current of the fan motor, rotation number detection means for detecting the rotation number of the fan motor, drive current detection means for detecting the drive current flowing through the fan motor, and rotation of the rotation number detection means Based on the number detection signal, a current setting signal to the drive current control means when the rotation speed of the fan motor matches a set rotation speed corresponding to the supply gas amount is stored, and the stored current setting signal is stored in the drive unit. A combustion control means for sending to the current setting means, wherein the drive current control means compares a current setting signal provided from the combustion control means with a detected drive current signal detected by the drive current detection means to thereby control the fan. The present invention is characterized in that control is performed such that the drive current of the motor matches the current setting signal.

[0011]

According to the fan control method of the present invention, the drive current of the fan motor when the fan motor matches the set rotation speed corresponding to the supply gas amount is set as a reference current value thereafter. Therefore, even if the ambient temperature changes, even if the characteristics of the individual fan motors are different, or even if headwinds occur, it is possible to supply the optimal combustion air corresponding to the supply gas amount at that time, Combustion can always be performed at the optimum mixing ratio. When the supply gas amount is changed, the set rotation speed is updated each time, so that even if the supply gas amount fluctuates, optimal combustion can be always maintained.

Further, when the supply gas amount is changed, a correction is made based on an error between a reference rotation speed corresponding to the supply gas amount before the change and an actual detected rotation speed before the change, so that the supply after the change is changed. Set a new set rotation speed for the gas amount ,
Drive of the fan motor when it matches this new set speed
The dynamic current is set as a subsequent reference current value . Therefore, even when the supply gas amount is changed, combustion can be performed at an optimum mixing ratio according to the actual rotation condition. Further, when the drive current of the fan motor is controlled to be constant at the reference current value as in the present invention, when a headwind is generated, the effect appears as a change in the rotation speed of the fan motor 7. Therefore, when a headwind is acting, the correction is performed using the actual rotation speed changed by the headwind, so that even if the headwind is acting, an optimal amount of combustion air can be supplied.

Further, in the case of the first fan control device of the present invention, the drive voltage of the fan motor is reduced by comparing the voltage setting signal supplied from the combustion control means with the drive voltage of the fan motor applied to the fan motor. Since the control is performed so that the drive current of the fan motor matches the reference current value, the optimum combustion can be automatically realized.

According to the second fan control device of the present invention, the drive current of the fan motor is determined by comparing a current setting signal provided from the combustion control means with a drive current signal detected by the drive current detection means. And the drive current of the fan motor is made to match the reference current value, so that the configuration of the combustion control means can be further simplified.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a first embodiment of the present invention. In the figure, 1 is a gas burner, 2 is a heat exchanger, and a gas proportional valve 3 for controlling a gas flow rate is connected to the gas burner 1. On the other hand, a water inlet temperature sensor 4 and a water flow sensor 5 are connected to the water inlet side of the heat exchanger 2, and a hot water temperature sensor 6 is connected to the outlet side.

Reference numeral 7 denotes a fan motor for supplying combustion air to the gas burner 1, reference numeral 8 denotes a rotation sensor for detecting the number of revolutions of the fan motor, reference numeral 9 denotes an AC / DC converter for converting an AC power supply voltage to a DC power supply voltage, and 10 denotes a DC / DC converter. AC / DC converter 9
A pulse width control unit 11 variably controls a DC power supply voltage sent from a pulse width signal having a predetermined pulse width and outputs the pulse waveform signal, and 11 converts the pulse waveform signal output from the pulse width control unit 10 into a DC voltage, A DC converter that supplies a drive voltage to the fan motor 7.

Reference numeral 12 denotes a voltage comparison unit which compares the output voltage of the DC conversion unit 11 with a voltage setting signal supplied from the combustion control unit 15, detects an error signal from the signal, and sends the error signal to the pulse width control unit 10. The circuit having the reference numerals 10 to 12 constitutes the drive current control unit 13 of the fan motor 7.

Reference numeral 14 denotes a drive current detection unit for detecting a drive current flowing through the fan motor 7, reference numeral 15 denotes a combustion control unit composed of a microcomputer or the like for controlling the operation of the entire apparatus, and reference numeral 16 denotes various operation keys and indicators. The operation unit is composed of The internal ROM 17 of the combustion control unit 15
Stores a reference rotation speed of the fan motor 7 that gives an optimum supply air amount corresponding to each gas supply amount. The reference number of revolutions stored in the built-in ROM 17 gives the set number of revolutions of the fan motor when there is no wind.

Next, the operation of the above embodiment will be described with reference to the flowchart of FIG. First, after setting the hot water temperature and the like by operating the keys and switches of the operation unit 16 (step S
1, S2), when the hot water supply faucet (not shown) is opened, the combustion control unit 15 supplies the amount of supply gas for obtaining the set hot water temperature based on the water temperature signal from the water temperature sensor 4 and the water flow signal from the water flow sensor 5. Is calculated, and the optimal supply gas amount for giving the set hot water temperature at that time is determined (step S3). The supplied gas amount is calculated by a calculating means such as a microcomputer or the like by the supplied gas amount = (set hot water temperature−water input temperature) × (water input amount).
It can be obtained by performing the calculation of × (efficiency).

The combustion control unit 15 controls the opening of the gas proportional valve 3 so as to achieve the determined supply gas amount, ignites the gas burner 1, and simultaneously reads the determined supply gas amount from the built-in ROM 17. The corresponding reference rotation speed of the fan motor 7 is read, and the read reference rotation speed is determined as a set rotation speed (step S4).
Is started so as to reach the set number of revolutions.

When the drive of the fan motor 7 is started as described above, the combustion control unit 15 confirms that the supply gas amount has not changed (step S5), and then changes the current operation state to the constant rotation speed control. Mode or drive current constant control mode is determined (step S6). When the drive of the fan motor 7 has just started, the process proceeds to the rotation speed control because the fan motor 7 has not yet reached the set rotation speed (step S7). Further, when the vehicle is in the steady operation by the drive current constant control described later, the process proceeds to step S14.

If the processing shifts to step S7 as a result of the determination in step S6, the combustion control unit 15 monitors the rotation speed of the fan motor 7 from the rotation pulse signal output from the rotation sensor 8 (step S8). Fan motor 7
Then, it is determined whether or not the rotation speed of the motor is equal to the determined set rotation speed.

When the rotation speed of the fan motor 7 increases and coincides with the determined set rotation speed, the combustion control unit 15 converts the detected current signal sent from the drive current detection unit 14 at that time to the set rotation speed. It is detected as a reference current value of the drive current to be performed and stored in an internal RAM (not shown) (step S9).

When the reference current value is detected and stored as described above, the process shifts to the drive current constant control mode (step S10) so that the drive current of the fan motor 7 is maintained at the reference current value. Feedback control is performed (step S11).

That is, the combustion control section 15 sends a voltage setting signal for giving a reference current value of the detected and stored driving current to the voltage comparing section 12, and the voltage comparing section 12 sends the voltage setting signal and the DC conversion section 11 The DC voltage is compared with the output DC voltage, and the error signal is sent to the pulse width control unit 10.
The pulse width control unit 10 controls the pulse width of the pulse waveform signal output based on the error signal sent from the voltage comparison unit 12, and varies the DC voltage output from the DC conversion unit 11, Feedback control is performed so that the drive current of the fan motor 7 matches the reference current value.

As a result, the drive current of the fan motor 7 is maintained at the reference current value corresponding to the set number of revolutions at which the optimum supply air amount is provided, so that the characteristics of the individual fan motors and the ambient temperature of the use environment differ. Also, combustion can be performed at an optimum mixing ratio. The temperature of the hot water discharged from the heat exchanger 2 is detected by the hot water temperature sensor 6 and fed back to the combustion control unit 15 to control the opening of the gas proportional valve 3 so that the temperature of the hot water is always set to the set hot water temperature. Is done.

Further, even if the load on the fan motor 7 is reduced by the headwind and the amount of air supplied to the gas burner 1 is reduced due to this, the drive current of the fan motor is kept at a constant reference current value. To be maintained in
The number of rotations of the fan motor 7 automatically increases by an amount corresponding to the reduction of the load due to the headwind, thereby preventing a decrease in the amount of air supplied to the gas burner 1 and maintaining stable combustion even in the headwind.

In step S8, it is practically extremely difficult to completely match the rotation speed of the fan motor 7 to the set rotation speed. Therefore, when actually configuring the apparatus, a value when the rotation speed of the fan motor 7 falls within a predetermined allowable range with respect to the set rotation speed, for example, ± 0.5
The value when the value falls within the range of% to ± 2% may be stored as the reference current value of the drive current. The allowable range is determined according to the magnitude of the set rotation speed. For example, when the set rotation speed is 1000 rpm, ± 2%, 4000 r
In the case of pm, it is set to ± 0.5% or the like.

If the supply gas amount is changed during the steady operation in the drive current constant control mode, it is detected in step S5, and the process shifts to step S12 to change the supply gas after the change. A setting process of a new set number of revolutions corresponding to the gas amount is performed.

That is, when the supply gas amount is changed, the combustion control unit 15 reads from the internal ROM 17 a new reference rotation speed of the fan motor 7 corresponding to the changed supply gas amount, An error between the reference rotation speed for the gas amount and the actual rotation speed of the fan motor 7 before the change is calculated, and based on the obtained error, a correction rate α = (old detection rotation speed−old reference rotation speed) / (Old reference rotation speed) is calculated, and the correction ratio α is multiplied by the reference rotation speed for the new supply gas amount read from the built-in ROM 17 to correct the rotation speed. It is determined as a new set rotation speed corresponding to the supply gas amount after the change (step S12).

After determining the new set number of revolutions, the mode shifts again to the number of revolutions control mode for detecting a new reference current value (steps S13, S6, S7). The detection and storage of the reference current value of the drive current corresponding to the new set rotation speed is performed (steps S8 to S8).
9).

As described above, even when the supply gas amount is changed, the optimum air amount corresponding to the changed supply gas amount is quickly supplied, and the combustion shifts to stable combustion in a very short time. Can be. The amount of gas supplied to the gas burner 1 always changes according to the amount of water flow and changes in water temperature.
As described above, since the set number of revolutions of the fan motor 7 changes quickly with the change of the supply gas amount, it is possible to always maintain the optimum combustion even if the supply gas amount changes.

When the supply gas amount is changed at the time of a headwind, the reference rotation speed read from the built-in ROM 17 is directly determined as a new set rotation speed of the fan motor 7, and the supply air amount corresponding to the headwind is determined. Will run out. However, in the present invention, such a problem can be solved by the correction processing in step S12.

That is, in the case of the present invention, the fan motor 7
Is controlled so that the reference current value is constant, so that the number of rotations of the fan motor 7 changes when a reverse wind occurs. Therefore, the occurrence of the reverse wind can be detected by the change in the rotation speed of the fan motor 7. And the fan motor 7
The amount of change in the number of rotations indicates the strength of the headwind. Since the correction rate α in step S12 is calculated using the actual rotation speed of the fan motor 7 changed by the headwind, the new set rotation speed obtained by multiplying the correction rate α is the strength of the headwind at that time. Is turned into the set number of revolutions, and as a result, an optimal amount of combustion air can be supplied even in the case of a headwind.

Further, during the steady operation by the drive current constant control, the actual rotation speed of the fan motor 7 becomes lower than the reference rotation speed due to, for example, a calculation error in the correction processing (step S12), or Even if the rotation speed of the fan motor 7 is increased in response to the headwind while maintaining the reference current value constant, the detected rotation speed falls below the reference rotation speed for some reason while the rotation speed is changed. Some things may happen. Therefore, in such a case, this is detected in step S15, the process is returned to steps S7 and S8, and the reference current value of the drive current is set again. Is controlled so that it can be maintained.

FIG. 3 is a block diagram of a second embodiment of the present invention. The second embodiment is different from the first embodiment in that a current comparator 12 'is used in place of the voltage comparator 12 in the drive current controller 13, and the detected current sent from the drive current detector 14 is used. The point is that the signal is directly sent to the current comparison unit 12. The same or corresponding parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The operation of the different parts will be briefly described. The combustion controller 15 monitors the number of revolutions of the fan motor 7 based on the rotation pulse signal from the rotation sensor 8.
The current setting signal to the current comparison unit 12 'is gradually changed. Then, when the rotation speed of the fan motor 7 matches the set rotation speed corresponding to the supply gas amount at that time, the current setting signal given to the current comparison unit 12 'from the combustion control 15 at that time is fixed and maintained. The current comparator 12 'is provided with the fixed and maintained current setting signal reference current value.

The current comparator 12 'compares the current setting signal supplied from the combustion controller 15 with the detected current signal sent from the drive current detector 14, and sends the error signal to the pulse width controller 10. send.

The pulse width control unit 10 includes a current comparison unit 12 '
By controlling the pulse width of the pulse waveform signal output based on the error signal sent from the DC converter 11 and varying the DC voltage output from the DC converter 11, the fan motor 7
The feedback control is performed so that the drive current of the reference current coincides with the reference current value.

According to the second embodiment, it is not necessary to send the drive current of the fan motor 7 detected by the drive current detector 14 to the combustion controller 15, so that the structure of the combustion controller 15 is simplified. At the same time, the control program incorporated in the combustion control unit 15 can be simplified.

In each of the embodiments described above, the drive current of the fan motor is controlled to be constant at the reference current value by the feedback control, but it is needless to say that the feed current control may be performed. Further, the present invention is not limited to the above-described embodiment, and various modifications can be made in accordance with the gist of the present invention.

[0042]

As described above, according to the present invention, even when the characteristics of individual fan motors differ or the ambient temperature changes, the amount of air that always provides the optimum mixing ratio is supplied to the combustion section. Optimum combustion can be achieved.

Further, since the drive current is maintained at a constant reference current value, even if the number of revolutions of the fan motor attempts to decrease due to the reverse wind, the number of revolutions of the fan motor automatically increases, and the combustion proceeds against the reverse wind. Since it acts to supply air, stable combustion can be maintained even in the case of a headwind.

Further, it is possible to quickly react to a change in the supply gas amount, and to determine a new set number of revolutions for the supply gas amount after the change, a reference value corresponding to the supply gas amount before the change. Correction is made based on the error between the rotational speed and the actual detected rotational speed before the change, so that even when headwinds are acting, an optimal amount of combustion air can be supplied and stable. Burned combustion can be maintained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a flowchart of the operation of the first embodiment.

FIG. 3 is a block diagram of a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas burner 2 Heat exchanger 3 Gas proportional valve 7 Fan motor 8 Rotation sensor 10 Pulse width control unit 11 DC conversion unit 12 Voltage comparison unit 12 'Current comparison unit 13 Drive current control unit 14 Drive current detection unit 15 Combustion control unit 16 Operation unit 17 Built-in ROM

Claims (3)

(57) [Claims] 1. A fan control method for a forced-blast type combustion device for controlling the number of revolutions of a fan motor so as to achieve a combustion air amount corresponding to a supply gas amount, comprising: setting a reference rotation number corresponding to the supply gas amount to a set rotation number; As before
Driving the fan motor, detects and stores the drive current of the fan motor when the rotation speed of the fan motor matches the set rotation speed as a reference current value for optimal combustion air supply, and changes the supply gas amount. The supply gas before the change
The reference rotation speed corresponding to the
An error with the number of turns is determined, and the supply gas after the change is determined based on the error.
Correction to the reference rotation speed corresponding to the
A new set rotation speed for the supply gas amount after changing the rotation speed
Then, the rotation speed of the fan motor is changed to the new set rotation speed.
The fan motor drive current when the number matches the optimum combustion air
Detecting and storing the reference current value for air supply, and after the reference current value is stored , controlling the drive current of the fan motor to be equal to the reference current value. Device fan control method. 2. A fan control device for a forced air blowing type combustion device for controlling the number of revolutions of a fan motor so as to have a combustion air amount corresponding to a supply gas amount, comprising: a drive current control means for controlling a drive current of the fan motor; Rotation speed detection means for detecting the rotation speed of the fan motor; drive current detection means for detecting a drive current flowing through the fan motor; rotation speed detection signal of the rotation speed detection means; and detection drive current of the drive current detection means. Based on the signal, the drive current when the rotation speed of the fan motor matches the set rotation speed corresponding to the supply gas amount is detected and stored as a reference current value of the drive current corresponding to the supply gas amount at that time. Combustion control means for sending a voltage setting signal for giving a value to the drive current control means, wherein the drive current control means is a voltage setting signal provided from the combustion control means. Fan control unit and controls so that the driving voltage of the fan motor is equal to the voltage setting signal by comparing the drive voltage applied to the fan motor. 3. A fan control device for a forced-blast combustion device for controlling the number of revolutions of a fan motor so as to have a combustion air amount corresponding to a supply gas amount, comprising: a drive current control means for controlling a drive current of the fan motor; Rotation speed detection means for detecting the rotation speed of the fan motor, drive current detection means for detecting the drive current flowing through the fan motor, and the rotation speed of the fan motor based on the rotation speed detection signal of the rotation speed detection means. A combustion control unit that stores a current setting signal to the drive current control unit when the rotation speed matches the set rotation speed corresponding to the supply gas amount, and sends the stored current setting signal to the drive current setting unit; The drive current control means compares the current setting signal provided from the combustion control means with the drive current signal detected by the drive current detection means, thereby controlling the fan motor. Fan control unit motor drive current and controls to match the current setting signal.