JP2510375B2 - Combustion fan controller - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fan for supplying combustion air to a burner, a rotation speed setting means for setting a target rotation speed of the fan based on a combustion amount, and a lower limit corresponding to the target rotation speed. Lower limit setting means for setting a current, and controlling the drive current of the fan so that the rotation speed of the fan matches the target rotation speed, and when the drive current decreases to the lower limit current, the drive current Relates to a combustion fan control device provided with a control means for controlling so as not to fall below the lower limit current.

[0002]

2. Description of the Related Art A combustion fan control device as described above is
For example, it is used for a water heater. The target rotation speed of the fan is set to a value such that the air-fuel ratio is maintained at a predetermined value. The rotation speed of the fan is controlled so as to be maintained at the target rotation speed. Here, if the exhaust gas is blocked, the air-fuel ratio will drop below a predetermined value even if the fan rotation speed is maintained at the target rotation speed. Therefore, by controlling the drive current of the fan so as not to fall below the lower limit current, the reduction of the air-fuel ratio is suppressed. That is, the lower limit current corresponds to the lower limit of the air-fuel ratio. Conventionally, for the same model, the lower limit current is set to the same value in advance.

[0003]

There are variations in the characteristics of the fans, and the air flow rates of the individual fans at the same drive current are not uniform. Therefore, when the lower limit current is set to the same value as in the above-mentioned conventional technique, the air flow rate of the fan varies when the drive current is equal to the lower limit current. As a result, the lower limit of the air-fuel ratio varies. An object of the present invention is to eliminate the above-mentioned conventional drawbacks and obtain a combustion fan control device capable of accurately controlling the lower limit of the air-fuel ratio.

[0004]

In order to achieve this object, the first characteristic configuration of the combustion fan control device according to the present invention is provided with an instruction means for instructing execution of the setting mode, and the setting mode is executed. In this case, the control means controls the rotation speed of the fan to a predetermined value, and the lower limit setting means sets the lower limit current based on the driving current value at that time. That is.

A second characteristic configuration is that an air temperature detecting means for detecting an air temperature is provided, and the lower limit setting means is configured to correct the lower limit current to a smaller value as the air temperature is higher. .

[0006]

The operation of the first characteristic configuration is as follows. During shipping inspection and installation work, the instruction means is activated to execute the setting mode. When you execute the setting mode,
The drive current value is obtained when the rotation speed of the fan is set to a predetermined value. This drive current value becomes a value corresponding to the characteristics of each fan. A current value smaller than the drive current value by the dead zone is set as the lower limit current.

The operation of the second characteristic configuration is as follows. The higher the temperature, the lower the density of air. That is, the higher the temperature, the smaller the load on the fan and the smaller the drive current. Therefore, the lower limit current is corrected to a smaller value as the temperature is higher, so that the fluctuation of the dead zone due to the temperature is suppressed.

[0008]

According to the first characteristic configuration, since the lower limit current corresponding to the characteristics of each fan is set, the lower limit of the air-fuel ratio can be accurately controlled regardless of variations in fan characteristics.

In the second characteristic configuration, since the fluctuation of the dead zone due to the temperature is suppressed, the lower limit of the air-fuel ratio can be controlled more accurately.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a water heater including a heat exchanger 1 for heating water, a burner 2 that heats the heat exchanger 1, and a fan 3 that supplies combustion air to the burner 2. Is provided. In the figure, W1 is a water supply passage for the heat exchanger 1, and W2 is a hot water supply passage W2. The fuel gas supply passage G1 for the burner 2 is provided with two on-off valves 4 and 5 for intermittently supplying the fuel gas and an electromagnetic gas amount adjusting valve 6 for adjusting the fuel gas supply. In the water supply passage W1, a water amount sensor S1 for detecting the amount of water supplied to the heat exchanger 1, and the heat exchanger 1
An incoming water temperature sensor S2 for detecting the incoming water temperature is interposed. A hot water outlet sensor S3 for detecting the hot water temperature of the heat exchanger 1 is provided in the hot water supply passage W2. In the figure, 7 is an igniter, 8 is a frame rod for detecting whether or not the burner 2 is ignited, and 9 is a thermometer as an air temperature detecting means for detecting an air temperature. These are connected to the controller H, respectively.

A main remote controller R1 for commanding control information to the controller H and a bath remote controller R2 are provided. The main remote controller R1 is provided with an operation switch 21, a hot water supply temperature display 22, a hot water supply temperature setting device 23, and the like for instructing the start / stop of the operation. The bath remote control R2 is provided with an operation switch 31, a hot water supply temperature indicator 32, an additional heating switch 33, a hot water switch 34, and the like. or,
Each of the main remote controller R1 and the bath remote controller R2 is provided with a setting mode switch SW as an instruction means for instructing execution of the setting mode.

The configuration of the controller H will be added. As shown in FIG. 2, an input unit 41 for inputting command information and detection information of each sensor from the main remote controller R1 and the bath remote controller R2, and a combustion amount for obtaining the combustion amount Gp of the burner 2 based on the information from the input unit 41 Calculation unit 42, combustion amount Gp
The rotation speed setting unit 43 that sets the target rotation speed Nf of the fan 3 based on the above, the fan drive unit 44 that controls the drive current If of the fan 3 so that the rotation speed of the fan 3 matches the target rotation speed Nf, and the fan 3 Speed detection unit 4 for detecting the rotation speed of
5, the current detection unit 4 for detecting the drive current If of the fan 3
6, a lower limit setting storage unit 47 that sets a lower limit current Il corresponding to the target rotation speed Nf, and an adjustment valve drive unit 48 that adjusts the opening of the gas amount adjustment valve 6 are provided. The correspondence relationship between the combustion amount Gp of the burner 2 and the target rotation speed Nf of the fan 3 is initialized in advance in the rotation speed setting unit 43 (see FIG. 6). That is, if the combustion amount Gp of the burner 2 is determined, the target rotation speed Nf of the fan 3 is determined. Basically,
The drive current of the fan 3 is controlled so that the rotation speed of the fan 3 matches the initial setting value of the target rotation speed Nf. However, when the drive current decreases to the lower limit current Il, the target rotation speed Nf is increased stepwise. Therefore, the drive current is controlled so as not to fall below the lower limit current Il. That is, using the controller H, a rotation speed setting unit 100 that sets a target rotation speed Nf of the fan 3, a lower limit setting unit 101 that sets a lower limit current Il corresponding to the target rotation speed Nf, and a drive current of the fan 3. And a control means 102 for controlling the.

The setting of the lower limit current Il in the setting mode will be described. When the setting mode is executed, the combustion amount Gp of the burner 2 is sequentially increased from B1 to B5 and the target rotation speed Nf of the fan 3 is sequentially increased from A1 to A5 as shown in FIG. Then, the drive current value data D of the fan 3 at that time
1 to D5 are sequentially detected. The obtained data is processed by the method of least squares, and as shown in FIG. 7, a straight line showing the correspondence between the target rotation speed Nf and the drive current value If is obtained. Based on this straight line, the coefficients K1 and K2 of the characteristic equation expressed by the equation 1 are obtained.

[Equation 1] If = K1 × Nf + K2 The lower limit current Il is expressed by Equation 2.

## EQU2 ## Il = 0.97 × η × If That is, the lower limit current Il is set based on the drive current value when the rotation speed of the fan 3 is controlled to a predetermined value. Here, η is expressed by Equation 3.

Η = (1 + 0.00367 × T0) / (1 + 0.00367 × T1) where T0 is the temperature in the setting mode and T1 is the temperature during actual use. That is, the lower the current I
It is designed to correct l to a smaller value.

Next, the operation of the controller H will be described with reference to the flowcharts shown in FIGS. The normal mode is executed except when the setting mode is executed by the setting mode switch SW. In the setting mode, first, the temperature T0 is detected, and then the burner 2 is operated as described above.
And the target rotational speed Nf of the fan 3 are sequentially increased to sequentially detect the drive current value data D1 to D5. Then, based on the obtained data, the coefficients K1 and K2 of the characteristic formula expressed by the equation 1 are obtained.

In the normal mode, first, it is determined whether or not hot water supply is necessary. If hot water supply is not required, then it is determined whether or not hot water supply is currently being performed. If the hot water is not being supplied up to now, it returns as it is. In addition, if the hot water is being supplied until now,
After executing the extinguishing process and the process of setting the counter C to 0, the process returns. When it is determined that the hot water supply is required, it is determined whether or not the ignition is being performed. Only when the ignition is not being performed, the ignition process for igniting the burner 2 is executed.
Then, the combustion control of the burner 2 is executed. In the combustion control of the burner 2, first, the combustion amount Gp of the burner 2 is obtained. Next, the target rotation speed Nf is obtained. The target rotation speed Nf is basically obtained from the relationship of FIG. 6, but the product of the predetermined value ΔN and the counter C is added to the target rotation speed Nf obtained from FIG. After that, the output is adjusted so that the obtained combustion amount Gp and the target rotation speed Nf match. Then, it is checked whether the drive current If at that time is larger than the lower limit current Il. When the drive current If is smaller than the lower limit current Il,
Add 1 to the counter C.

[Other Embodiment] In the above embodiment, a plurality of data are processed by the least squares method to obtain a straight line characteristic expression representing the correspondence between the target rotation speed Nf and the drive current value If. The characteristic equation may be obtained by connecting two pieces of data with a straight line.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 Overall configuration diagram

FIG. 2 is a block diagram of a control configuration.

FIG. 3 is a flowchart of control operation.

FIG. 4 is a flowchart of control operation.

FIG. 5 is a flowchart of control operation.

FIG. 6 is an explanatory diagram showing a relationship between a combustion amount and a target rotation speed.

FIG. 7 is an explanatory diagram showing a relationship between a target rotation speed and a drive current.

[Explanation of symbols]

 2 burner 3 fan 9 air temperature detecting means 100 rotation speed setting means 101 lower limit setting means 102 control means If drive current Il lower limit current Nf target rotation speed SW instructing means

Claims (2)

(57) [Claims] 1. A fan (3) for supplying combustion air to a burner (2), and a rotation speed setting means (100) for setting a target rotation speed (Nf) of said fan (3) based on a combustion amount.
And the lower limit current (I) corresponding to the target rotation speed (Nf)
l) and a lower limit setting means (101) for controlling the drive current (If) of the fan (3) so that the rotation speed of the fan (3) matches the target rotation speed (Nf), and A control means (10) for controlling the drive current (If) so as not to fall below the lower limit current (Il) when the drive current (If) decreases to the lower limit current (Il).
2) is provided, and an instruction means (SW) for instructing execution of a setting mode is provided, and when the setting mode is executed, the control means (102) Combustion configured to control the rotation speed of the fan (3) to a predetermined value and to set the lower limit current (Il) based on the drive current value at that time by the lower limit setting means (101). Fan controller. 2. An air temperature detecting means (9) for detecting an air temperature is provided, and the lower limit setting means (101) is configured to correct the lower limit current (Il) to a smaller value as the air temperature is higher. The combustion fan control device according to claim 1.