JPH04158114A - Fan motor rotational frequency controller for burner - Google Patents

Abstract

PURPOSE:To enable a phase control to be achieved even when a reference duty factor is determined considerably finely, by providing a switching element for controlling a fan motor, and a microcomputer having a cycle-skipping control function for first energizing for one cycle and deciding whether energization is to be conducted in the next one cycle by comparing the current duty factor with a reference duty factor. CONSTITUTION:A cycle-skipping control is applied to rotational frequency control for a fan motor of a convection fan 7 or a combustion fan 8. The control is based on a system of first energizing for one cycle and subsequently deciding whether energization is to be carried out in the next one cycle by comparing a reference duty factor (in this example, 70/100) with the current duty factor. On the first energization for one cycle, the current duty factor is 1/1, which is greater than 70/100, and it is therefore decided that energization is not to be carried out for the next one cycle. On this non-energization, the current duty factor is 1/2, which is smaller than 70/100, and therefore energization is to be performed for the next one cycle. When the operation 18 repeated over 100 cycles, a substantially uniform cycle skipping is achieved. It is thus possible to achieve a considerably fine control of rotational frequency of a fan motor.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a combustor equipped with a convection fan or a combustion fan, and more particularly to a control device for controlling the speed capability of these fan motors.

Conventional technology Conventionally, the rotation speed control of this type of fan motor is based on phase control (Unexamined Japanese Patent Publication No. 1-2), which lowers the energization rate by cutting off the phase of the power supply.
69821), or wave removal control is used, and wave removal control is performed repeatedly, such as always energizing several waves and removing one wave.

Problems to be Solved by the Invention However, among the above conventional methods, phase control cuts the phase to reduce the energization rate, so the fan motor must be turned on at a high voltage, and is susceptible to noise. This had the disadvantage that the phase cut width had to be determined using a highly accurate timer in the microcomputer software, making programming complicated.

In addition, in wave removal control, if the number of waves is energized regularly, 1
Since the wave is removed, for example, if 6 waves are energized and 1 wave is removed, the energization rate will be 6/7, but the energization rate is 273.3/4.415゜5/6.6/7. As such, it was impossible to do so with a limited energization rate, and detailed control during that time was not possible.

Means for Solving the Problems The present invention has been made to solve the above-mentioned drawbacks, and consists of a commercial power supply zero-volt cross detection circuit, a switching element (in this example, a phototriac) that controls a fan motor, and a single-wave energization circuit. From then on, compare the standard energization rate and the current energization rate, and if the current energization rate is less than the standard energization rate, energize the next wave, so that the current energization rate is higher than the standard energization rate. It is equipped with a microcomputer that has a function to perform wave removal control such as de-energizing when the voltage is large, and controls the rotation speed of the fan motor.

In the present invention, a reference energization rate is determined and compared with the current energization rate to determine whether to energize or disconnect the next waveform. Therefore, it is possible to control even if the reference energization rate is determined very precisely.

Example An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic circuit diagram of a combustor according to the present invention, and 1
indicates a commercial power supply, 2-2 is a relay for controlling the ignition heater 6, and 3-2 is a switching element (phototriac) for controlling the convection fan 7 for sending warm air into the room -4- 2 is a switching element (phototriac) for controlling the combustion fan 8 for supplying combustion air; 5-2 is a relay for supplying power to the pump drive circuit 9; these are connected to the power supply 1- are connected in parallel. In addition, the pump movement circuit 9 is a pump l
This is a circuit for moving O and supplying oil. 11 is a transformer, a bridge diode 12 for rectification is connected to the secondary side of the transformer, smoothing is performed by a smoothing capacitor 14, and relays 2-1.5-1. A switching element (phototriac) constitutes a power supply to be supplied to 3-1.4-1. And 13 is a constant voltage regulator, which is a microcontroller]
It constitutes the power supply of 5. 16 is a room temperature detection circuit;
This is a circuit for detecting room temperature using a thermistor, etc.
By inputting a signal to the microcomputer 15, the microcomputer 15
performs A/D conversion and detects room temperature.

17.]8.19.20 is a driver for relay 2-1.5-1 and phototriac 3-1.4-1.

21 and 22 indicate limiting resistors for limiting the current flowing to the diode side of the phototriac. Further, 23 is a zero volt detection circuit for detecting a zero volt cross point of the commercial power supply 1.

Here, the basic operation of the combustor in the present invention will be explained. First, the combustion fan 8 is rotated to supply air for combustion, the ignition heater 6 is energized to drive the pump 10, oil is supplied and a flame is formed, and later the convection fan 7
Rotate to blow out warm air. Although it is not shown in Fig. 1 during combustion, a set room temperature can be set, and the amount of combustion is switched from strong to slight combustion in consideration of the difference from the room temperature detected by the room temperature detection circuit 16. The amount of oil is determined by outputting a signal from the microcomputer 15 to the pump drive circuit 9.
The amount of oil is changed accordingly. Further, the convection fan 7 and the combustion fan 8 are operated by a phototriac 3.
The air volume is changed by changing the energization rate in step 4.

The present invention performs wave removal control as shown in FIG. 2 (1) regarding the rotational speed control of the fan motors of the above-mentioned convection fan 7 and combustion fan 8.

This is the zero volt detection circuit 2 as shown in Figure 2 (2).
The microcomputer 15 detects the signal from the phototriac 3-1 as shown in FIG. 2 (3).
．． By removing only one wave of the output to 3-2.4-1.4-2, the phototriac 3-1.3-2.4-1.4
This is to lower the rotation speed by lowering the energization rate to -2.

Also, when you want to achieve the target rotation speed, set the energization rate to 70, for example.
%, if 70 out of 100 waves are energized,
It is sufficient to de-energize 30 waves, but in this case, 7 waves
If you energize for 0 waves in a row and then de-energize for 30 waves in a row, the rotational speed will become uneven, so as shown in the flowchart in Figure 3, first energize for 1 wave, and then energize for 30 waves in a row. The method is to compare the energization rate (70/100 in this example) and the current energization rate to decide whether to energize or de-energize the next wave.9 In other words, when the first wave is energized, the current energization rate is Since it is 1/1, comparing 1/1 and 70/100, it is 70/1 (since 10 is smaller, the next wave will be de-energized. And because of de-energization, the current energization rate is 1/1) 2
Therefore, compared to 70/100, 707100 is larger, so the next wave will be energized. As a result, the current energization rate is 2/3, which is 70 compared to 70/100.
/100 is larger, so power is applied next time as well. The current energization rate is 3/4, and since 70/100 is smaller, the next time it will be de-energized. Then, the current energization rate becomes 375, and since 70/100 is larger, the current will be energized next. And the current energization rate is 4/6, which is 70
/100 is larger, so power is applied next time as well. If this is done up to 100 waves, the waves will be removed almost evenly and the energization rate will be 70%, and the next wave will be calculated in the same way up to 100 waves, and this will be repeated.

Effects of the Invention According to the present invention, the rotation speed of the fan motor can be controlled quite finely, and the microcomputer software does not require a highly accurate timer, making it simple. Since it is a zero-volt cross, it has the effect of reducing noise. In this example, 100
Since calculations are made from the beginning again at each wave, the standard energization rate can be set in 1% increments (for example, 7
0%, 71%, 72%), if you cancel every 1000 waves, you can set it in 0.1% increments (for example, 70%, 70.1%, 70.2%).
) has advantages.

[Brief explanation of the drawing]

FIG. 1 is a schematic circuit diagram of a combustor according to the present invention, and FIG. 2 shows a voltage between the fan motor, a zero volt detection waveform, and a microcomputer output diagram to the phototriac when controlling according to the present invention. FIG. 3 shows a flowchart of an embodiment of the present invention. 3-1.3-2 is a switching element (phototriac), 4-1.4-2 is a switching element (phototriac), 7 is a convection fan, 8 is a combustion fan, 1
5 is a microcomputer, and 23 is a zero-volt cross circuit. Applicant Hitachi Homechick Co., Ltd. Figure 3

Claims (1)

[Claims] In a combustor control device that is equipped with a convection fan (7) or a combustion fan (8) and controls the rotational speed capability of these fan motors, a commercial power zero volt cross detection circuit (23) and a fan motor are controlled. First, one wave is energized with the switching element, and from then on, the standard energization rate and the current energization rate are compared, and if the current energization rate is less than the standard energization rate, the next wave is energized, A combustor fan motor rotation speed control device comprising a microcomputer (15) having a function of performing wave removal control such as de-energizing when the current energization rate is greater than the reference energization rate.