JPS59129324A - Control device for combustion - Google Patents

Abstract

PURPOSE:To contrive to prevent a change in the temperature in effluent hot-water when the voltage in power supply source is fluctuated, by providing a control circuit which calculates the target revolution number of a fan motor and a circuit which detects the actual number of revolutions of a fan motor. CONSTITUTION:The primary control circuit 22, a number of revolutions detector 23, and the secondary control circuit 24 are provided in a combustion controlling device. The primary control circuit 22 calculates the target number of revolutions of a fan motor 5 by the temperature detecting signal from a temperature sensor 2 and the temperature setting signal from a temperature setter 3, and puts out the calculated result to the circuit 24. The number of revolution detector 23 detects the actual number of revolutions of a fan motor 5. On the other hand, the secondary control circuit 24 calculates to put out a phase controlling signal from a phase controlling circuit 24b which is not shown, by the signals from the number of revolutions detector 23 and from the control circuit 22, respectively. The number of revolutions of a fan motor 5 and the gas feed rate to a burner 4 are controlled by the phase controlling signals from the control circuit 24. With such an arrangement, a combustion control device which has good response property and no change in the temperature in effluent hot-water even if the voltage in power source is fluctuated, can be obtained.

Description

Detailed Description of the Invention (a) Field of the Invention In this invention, for example, a predetermined control amount is determined by PID calculation from the deviation between the hot water outlet temperature of the heat exchanger and the target temperature, and this control amount is used to control the shift fan motor drive signal. A combustion control device that controls the rotation speed by changing the phase, controls the amount of combustion in the burner according to the amount of hot water released, and maintains the hot water temperature at a target temperature, especially for phase control.

This invention relates to a coffin ware control device that controls heat.

(B) Background of the Invention FIG. 1 is a diagram showing the basic configuration of a water heater equipped with a combustion control device in which the present invention is implemented. In the figure, 1 is a heat exchanger.

2 is a thermistor that detects the hot water temperature of the heat exchanger 2;

B is a temperature setting device that sets the target temperature, and 4 is a burner.

5 is a fan motor that supplies air to the burner 4; 6 is a control that controls the number of times of the fan motor 5 based on the deviation between the hot water temperature signal detected by the thermistor 2 and the target temperature setting signal of the temperature setting device B; A rotary valve 7 is provided in the gas supply path to the burner 4, and operates so that the valve opening changes according to the blowing air mark of the fan motor 5, and the gas pressure supplied to the burner 4 is proportional to the air pressure. It is a pressure equalizing valve.

8 is a flow rate detector installed at the water inlet leading to the heat exchange surface 1 to detect the water flow to the heat exchanger 1 and input a high signal to the control circuit B; 9 and 10 are gas supplies leading to the pressure equalization valve 7 a source valve and a gas governor installed in the road to turn on and off the gas supply; 11 an igniter that generates 9 ignition sparks for the burner 4;
Reference numeral 12 is a flame detector for detecting whether or not the ignition is normally ignited by the ignition operation, and reference numeral 13 is a wind pressure switch for checking the operation of the fan motor 5.

FIG. 2 is a block diagram showing an operational system for hot water temperature control performed by the control circuit 6 shown in FIG. 1, and this control system is constituted by a feedback loop. Figures 1 and 2 below
The basic operation of the water heater will be explained with reference to the drawings.

□ First, when the water flow in the heat exchanger 1 is detected by the flow rate detector 8, the control circuit 6 opens the main valve 9 and closes the 5
Activate igniter 1.1. At the same time, the fan motor 5 is driven. Then, the amount of air blown by the fan motor 5 increases toward a predetermined value, and accordingly, the valve opening of the pressure equalizing valve 7 increases in proportion to the air pressure, and the gas combustion in the burner 4 grows toward a predetermined state. . When the hot water temperature of the heat exchanger 1 rises, it is detected by the thermistor 2, and the control circuit 6
The operation is performed according to the control system shown in the figure.

That is, the control circuit 6 finds a deviation C between the hot water temperature detection signal a and the target temperature layer υb, performs a PID calculation on this deviation C, and creates a predetermined control Jild.

Based on this control ID, the phase angle of the rotating magnetic field that drives the rotor of the fan motor 50 is calculated and determined.

Outputs signal e. This output signal e is applied as a trigger signal to a switching element that turns on and off the drive current of the fan motor 5. The switching element controls the drive current of the fan motor 5 at a conduction angle determined by the trigger signal C, and the fan motor 5 rotates at a predetermined rotational speed under a rotating magnetic field of the order of magnitude +. As a result, a predetermined air pressure f corresponding to this rotational speed is transmitted to the pressure equalizing valve 7, the opening degree of the pressure equalizing valve 7 becomes a predetermined opening degree, and the amount of gas supplied to the burner 4 becomes appropriate. In this way, the hot water temperature is controlled to the set temperature. The above operation is then repeated to maintain the tapped water temperature at the set temperature, and the burner 4 continues combustion with a predetermined amount of gas. If there is a change in the set temperature or amount of hot water.

Changes in the hot water temperature are fed back, and the hot water temperature is corrected by the control operation described above.

Now, in the above combustion control device, if the operating point is within the controllable range of the fan motor 5.

Even if the power supply voltage fluctuates and the rotation speed of the fan motor 5 changes, and the hot water temperature changes temporarily, the change is fed back, and the hot water temperature is stabilized at the target temperature by the control operation described in section 2.

However, as shown in Figure 6, if the combustion capacity is at its maximum and minimum, it is impossible to control further, and fluctuations in the power supply voltage will continue to change the hot water temperature. become. In other words, as shown in Figure 3, when the drive current angle of the fan motor 5 is θInax, which corresponds to the maximum combustion capacity, at the rated voltage (a
), it is possible to control with the signal area A, but when the power supply voltage drops below the rated value, as shown in the same figure (b), the narrow area B (signal area B), which affects combustion, becomes smaller than the rated value. When the signal area A is smaller than the signal area A at the time of freezing, the combustion capacity decreases, and as shown in Figure 6, the fan motor rotation speed and hot water temperature decrease due to the decrease in power supply voltage, making control impossible. As shown in Figure 6], the phase angle of the drive current of the fan motor 5 is at a minimum of 11'II Ul.
In the case of (a) at rated power, it is possible to control the signal area C, but if the power supply voltage is lower than the rated voltage as shown in (b) of the same figure, When the engine rises, the signal area C that contributes to combustion becomes larger than the signal area C at the fixed crane, and the combustion capacity increases.

As shown in (l) of Fig. 6, the fan motor rotation speed and the hot water temperature increase due to the increase in power supply voltage, making it impossible to control.

Even if it is still within the control range, the combustion control device (2) corrects the fan motor rotation speed and gas supply amount after the thermistor 2 detects a change in the outlet temperature, so changes in the outlet temperature are inevitable. Therefore, it has the disadvantage of poor responsiveness.

The above-mentioned change in outlet temperature is not desirable for users of water heaters, and it is desirable to eliminate it.

e→Object of the Invention Therefore, an object of the present invention is to provide a combustion control device that does not cause a change in outlet temperature even if a change in power supply voltage occurs, and has good response tolerance.

B) Structure and Effects of the Invention In order to achieve the above object, the combustion control device of the present invention has the following features:
a first control circuit that calculates and outputs a target rotational speed of the fan motor based on a temperature detection signal from a temperature detector and a temperature setting signal from a temperature setting device;

A rotation speed detector that detects the rotation speed of the fan motor.

A second control circuit is provided which calculates and outputs a phase control signal of the phase control circuit based on the detected rotation speed signal from the rotation speed detector and the output @ of the first control circuit. The rotational speed of the fan motor and the gas supply to the burner are controlled by the phase control signal of the fan motor.

According to the combustion control device of the present invention, even if the power supply voltage varies depending on the IC, the rotation speed of the fan motor and the hot water temperature may change, the second control circuit performs feedback control of the rotation speed and the hot water temperature. change can be suppressed.

Furthermore, since feedback control of the rotation speed of the fan motor (7) is performed by the second control circuit even when the operation is within the control range, the control of the fan motor (7) is more efficient than in the case of only feedback control of the hot water temperature. can be done.

01 → Description of examples Hereinafter, the present invention will be explained in more detail with reference to Examples.

The basic structure of the water heater υ1 to which the combustion control device of the embodiment described below is applied is the same as that shown in FIG. 1.

FIG. 4 is a block diagram of a control system showing one embodiment of the present invention.

In FIG. 4, 20 is a set temperature circuit, and 21 is a hot water temperature detection circuit, which correspond to the temperature setting device and thermistor 2, respectively. 2 is a PID calculation circuit 22a and a rotation speed calculation circuit 2
2b, and this first control circuit is a circuit for creating a rotation speed signal of the fan motor according to the set temperature signal and the detected hot water temperature signal a. 23
24 is a rotation speed detection circuit having a detector for detecting the rotation speed of the fan motor 5; 24 is a second control circuit consisting of a PI calculation circuit 24n and a phase calculation circuit 24b; The rotation speed signal C calculated by the control circuit 1 and the rf of the fan motor 5 detected by the rotation speed detection circuit 26
lJ is a circuit for calculating the phase control signal of the fan motor based on the number of revolutions r. Note that 25 is a maximum/minimum limit circuit that controls the maximum combustion capacity and the minimum limit so that the combustion capacity does not become too small and the combustion becomes unstable, or the hot water heater does not heat up due to combustion with excessive capacity. This is a circuit to limit combustion capacity to a certain range. 2
6 is a fan motor IIK movement Fl path; 27 is a gas supply control unit that controls the amount of gas supplied to the burner 4 using air pressure from the fan motor 5; As is clear from the figure, this control system is equipped with a ride pack loop based on water temperature detection similar to that shown in FIG. 2, as well as a feedback loop based on two revolution speed detections. A specific circuit diagram of this control system is shown in FIG.

Next, the operation of the embodiment combustion control device will be explained with reference to FIGS. 1 and 4.

First, when the thermistor 2 detects the hot water temperature of the heat exchanger 1, the hot water temperature detection signal a from the hot water temperature detection circuit 21 and the target temperature signal b from the set temperature circuit 2o are l! i? To +,
C is calculated and the PID calculation circuit 22a'''
cPID calculation is performed to create a predetermined control amount d, and then, based on this control amount d, the 2 rotation speed calculation FIWb 22b calculates and determines the rotation speed of the rotor of the fan motor 5, and outputs 8 rotation speed signal C. do. Next, the deviation g between the rotational speed signal e and the rotational speed detection signal f from the rotational speed detection circuit 23 is determined, and the PI calculation circuit 24+a performs a PI calculation on this deviation g to create a predetermined control amount II. Next, based on this control scale, the digit calculation circuit 24b calculates and determines the phase angle of the rotating magnetic field that drives the rotor of the fan motor 5, and outputs a phase signal i. Furthermore, the phase signal 1 is subjected to maximum and minimum value limitations in a maximum/minimum limitation circuit 2S, and is output as a signal J. This signal J is applied as a trigger signal to a switching element that turns on and off the drive current of the fan motor 5-. The switching element controls the phase of the drive current of the fan motor 5 according to the conduction angle determined by this trigger signal, and the rotation speed of the fan motor 5 obtained by the rotation speed detection circuit 26 is adjusted according to this control.
The rotation speed detection signal f and the rotation speed signal e are again output to the ratio motor 5.
becomes a predetermined number of rotations.

As a result, a predetermined air pressure k corresponding to this rotational speed is transmitted to the pressure equalizing valve 7 of the gas supply amount control section 27.

The opening degree of the pressure equalizing valve 7 becomes a predetermined opening degree, and the amount of gas supplied to the burner 4 becomes appropriate. In this way, the hot water temperature is controlled to the set temperature. The above operation is then repeated to maintain the tapped water temperature at the set temperature, and the burner 4 continues combustion with a predetermined amount of gas.

Next, with reference to FIG. 5, in the combustion control device of the above embodiment, when combustion is occurring at the maximum capacity at the rated power supply voltage and the power supply voltage drops, and when combustion is occurring at the minimum capacity at the rated power supply voltage and the power supply voltage decreases. The operation when it rises will be explained.

Figure 5] shows the signal waveform when the power supply electrons are reduced due to combustion at maximum capacity at the rated power supply voltage.
) is the signal waveform at the rated power supply voltage, and (b) in the figure is the signal waveform at the time of the power supply voltage drop. Since it has the maximum capacity, rotation speed calculation circuit 2
The rotational speed signal of 2b and 2 does not change + acid m + j ”h:
The fan motor 750 rotation speed is 1 degree lower than the pressure 1 bar ("-").
occurs. Based on this new deviation g, the second Mll114
1 circuit 240 phase calculation circuit 24-b outputs a new phase signal i1, and as shown in FIG. By making the signal area (A) and signal area B equal, we can calculate the rotational speed drop due to the direct voltage drop (ft). As a result, as shown in Fig. 5 (
C) [As shown in a'l, even if the power supply voltage drops by υ from the rated state when the combustion capacity is at its maximum, the fan motor's 50 rpm and the hot water temperature only drop slightly and become stable immediately] Return to the throat .

Figure 5 (B3 shows the number waveform when combustion is performed at the minimum capacity at the rated power supply's voltage and the pressure in the tunyuan area increases; in this case, Figure 5 above (contrary to the case of N) .

The conduction sound is reduced from θmin to θ'min, and the signal area is made equal to reduce the surface pressure on the upper row of rotational speeds caused by the increase in power supply voltage. As a result, as shown in (b) of Figure 5, even when the combustion capacity is at the minimum of 3, the fan motor 50 rpm and the hot water temperature rise slightly even if the acid source pressure increases even more than at the rated value. It quickly returns to a stable state.

In the combustion control device of the above embodiment, if the power supply voltage fluctuates while combustion is occurring between the maximum combustion capacity and the minimum combustion capacity when the power supply voltage is rated, the rotation speed of the fan motor 5 will also change. The converted rotation speed is detected by the rotation speed detector of the rotation speed detection circuit 23, and the current rotation speed signal f
is fed back and the deviation g from the rotation speed signal e from the first control circuit 22 is calculated, a new phase @ is calculated in the second control circuit 24, and the rotation speed of the fan motor 5 is controlled by this phase signal. Since the fan motor 5 is set to a predetermined rotation speed before fluctuations in the power supply voltage affect the hot water temperature, stable and responsive control can be achieved even with independent feedback from the hot water temperature detection circuit 21. .

[Brief explanation of drawings]

Fig. 1 is a diagram showing the basic configuration of a water heater, and Fig. 2 is a block diagram showing the operation system of a conventional control circuit in the water heater.
Figure 3 is a diagram for explaining the effect of the electric zero mixed pressure change 1rJJ in the conventional combustion control device. CB) in the same figure is a waveform diagram showing the effect when the stain source voltage rises above the rated power supply voltage with minimum capacity combustion.
C) is the time chart shown in FIG. 6 above], FIG. 3 is a time chart showing changes in fan motor rotation speed and hot water temperature due to fluctuations in power supply voltage, and FIG. 4 is a combustion diagram showing an embodiment of the present invention. FIG. 5 is a block diagram showing the operation system of the control circuit of the control device. Figure (5) shows that when combustion is at maximum capacity and the power supply voltage drops below the rated power supply voltage, Figure (CB) shows that when combustion is at minimum capacity, the rated power supply voltage and source voltage decrease. The waveform diagram showing all the changes in the conduction angle when the conduction angle rises is shown in the fifth figure.
Figure 5 is a time chart showing changes in fan motor rotation speed and hot water temperature due to fluctuations in source acid pressure in the town, Figure 6 is a concrete circuit of the embodiment block diagram shown in Figure 4. FIG. 1: heat exchanger, 2: thermistor, 3: wetness setting device,
4: Pana, 5: Fan motor. 7: Pressure equalization valve, 20: Set temperature circuit. 21: Hot water temperature detection circuit, 22: First control circuit. 22a: PID calculation circuit, 22b: rotation speed calculation circuit, 23: rotation speed detection circuit. 24: Second control circuit, 24a: PI calculation circuit. 24b=phase calculation circuit, 25: maximum/minimum limit circuit.

Claims (2)

[Claims] (1) A temperature detector that detects the hot water temperature of a heat exchanger whose hot water temperature changes due to combustion in the burner, a temperature setting device that sets a target hot water temperature, and a fan motor that supplies combustion air to the burner; A phase control circuit that controls the rotation speed of the fan motor in accordance with a detection signal from the temperature detector, and a valve opening degree that changes in accordance with the air pressure of the fan motor to adjust the amount of fuel supplied to the burner. In the combustion wound device 1, the apparatus includes a pressure equalization valve and controls the hot water temperature of the heat exchanger to be maintained at a target temperature. a first control circuit that calculates and outputs a target rotational speed of the fan motor based on a temperature detection signal from the temperature detector and a temperature setting signal from the temperature setting device; and a first control circuit that detects the rotational speed of the fan motor. and a second control circuit that calculates and outputs the phase control signal of the phase control circuit based on the detected rotation speed signal from the rotation speed detector and the output signal of the first control circuit. A combustion control device characterized by: (2) The second control circuit has a phase control signal whose maximum signal output is such that the burner achieves maximum combustion even at the lower limit of the power supply voltage range used, and The combustion according to claim 1, characterized in that the burner is outputted through a maximum/minimum limiting circuit whose maximum signal output is such that the burner achieves minimum combustion even at the upper limit of . Control device.