JPS5941379Y2 - Forced draft heater - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a forced draft heater that uses a fan motor to suck combustion air into a combustor and exhaust combustion gas.

In conventional combustors of this type, the rotation speed of the fan motor is constant, so the fan air volume is also constant, and when the amount of heat is adjusted, high thermal efficiency can be achieved when the ratio of heating charge and combustion air amount is appropriate. It will be done.

However, if the ratios are different, the combustion condition deteriorates and the thermal efficiency decreases.

The purpose of this invention is to eliminate the above drawbacks.
By changing the rotation speed of the fan motor and changing the fan air volume, the amount of combustion air adapted to the amount of combustion is supplied.
The ratio of fuel and combustion air is adjusted to the optimum state.

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

In the figure, 1 and 2 are power supply terminals, 3 is a transformer, its primary side is connected to power supply terminals 1 i 2, and its secondary side is connected to diodes 4 and 5.
are connected to the anodes of each.

6 is a smoothing capacitor, and its positive terminal is connected to diode 4.
, 5 are connected to the center tap of the transformer 3, respectively.

A constant voltage diode 8 is connected in parallel with the capacitor 6 via a resistor 7, and a series circuit of a resistor 9 and a capacitor 10 and a series circuit of resistors 11 and 12 are connected in parallel to the diode 8.

13 is a programmable unijunction transistor (hereinafter referred to as PUT), its anode is at the connection point between resistor 9 and capacitor 10, and its gate is connected to resistors 11 and 1.
2, its cathode is NPN via a resistor 14.
150, each connected to a base.

The collector of the transistor 15 is connected to the connection point between the variable resistor 16 and the capacitor 17 and the negative inverting input terminal of the comparator 20, and the emitter of the transistor 15 is connected to the anode of the constant voltage diode 8.

The positive inverting input terminal of the comparator 20 is connected to the resistor 18,
19 connection point aK, the same power supply terminal is a constant voltage diode 80
The cathode and anode output terminals are connected to the base of an NPN transistor 220 via a resistor 21, respectively.

The emitter and collector of the transistor 22 are connected to the anode of the voltage regulator diode 8 and the photoisolator 24.
The light emitting diode parts of each are connected to the cathode,
The anode of the light emitting diode portion is connected to the cathode of a constant voltage diode Bo) via a resistor 23.

The base of the phototransistor portion of the photoisolator 24 is connected to a resistor 25 to the negative terminal of the rectifier stack 35, and the collector of the photoisolator 24 is connected to the positive terminal of the rectifier stack 35 via a resistor 26. It is connected to the gate of the thyristor 31 via a resistor 29.

The gate and anode of this thyristor 31 are connected to a negative terminal and a positive terminal of a rectifier stack 35, respectively.

A cathode of a constant voltage diode 25 is connected to one positive terminal of the rectifier stack 35 via a resistor 28.

One end of a resistor 32 and a capacitor 34 are connected, and the anode of a constant voltage diode 27, a resistor 30, and one ends of capacitors 33 and 34 are connected to the other negative terminal.

Further, one AC input terminal of the rectifier stack 35 is connected to the power supply terminal 1 via the fan motor 36, and the other AC input terminal is connected to the power supply terminal 2.

Next, the operation of this embodiment having the above-described configuration will be explained.

When an alternating current voltage is applied to the power supply terminals 1 and 2, the secondary side of the transformer 3 is rectified and smoothed by the diodes 4 and 5, the capacitor 6, the resistor 7, and the voltage regulator diode 8, and is made to have a constant voltage.

Further, PUT 13 oscillates via resistors 9, 11, 12 and capacitor 10.

On the other hand, the capacitor 17 is filled with the time constant due to the variable resistor 16, and the connection point between the resistor 16 and the capacitor 17 is the resistor 1.
A comparator 20 compares the respective voltages at the connection point a of the terminals 8 and 19.

The output voltage (current) is obtained during the time until the voltages at points a and b become the same and the comparator 20 is inverted,
Transistor 22 turns on, lights up the light emitting diode portion of photoisolator 24, and transmits a signal to the phototransistor portion.

In this case, the current flowing through the fan motor 36 is rectified and smoothed by the rectifier stack 35 and the capacitor 34, and then controlled by the thyristor 31.

The signal for turning on the thyristor 31 is controlled by the phototransistor portion of the photoisolator 24.

Here, the phototransistor portion of the photoisolator 24 is turned on until the voltages at points a and b become the same, so the gate of the thyristor 31 does not turn on because the signal cannot be changed.

Therefore, the fan motor 36 is not driven due to the minute size R.

When the voltage at the point mentioned above becomes equal to or higher than the voltage at point a, the phototransistor portion of the photoisolator 24 is turned off, and a turn-on signal is given to the gate of the thyristor 31, so the thyristor 31 is turned on and the fan is turned off. The motor 36 is energized and driven.

Note that by turning on the PUT 13 and the transistor 15, the charge in the capacitor 17 is discharged, and the comparator 20 returns to its initial state.

By selecting the time constant of each component so that the time constant when charging the capacitor 17 is always smaller than the time constant when charging the capacitor 10 as described above, the fan motor 360 is energized within the oscillation cycle of the PUT 13. control the time,
The rotational speed of the motor 36 can be changed steplessly and continuously.

As explained above, according to the present invention, by steplessly and continuously changing the rotation speed of the fan motor, the fan air volume is changed and the combustion air amount adapted to the combustion amount is supplied, and the fuel and combustion air are The ratio can be adjusted to the optimum state.

Therefore, it is possible to improve the thermal efficiency of the heater and reduce maintenance costs.

[Brief explanation of the drawing]

The drawing is an electrical circuit diagram of an embodiment of a forced draft combustor according to the present invention. 9.11,12...Resistance, 10,17...
... Capacitor, 13 ... Voltage comparator, 1
5, 22... - Transistor, 16...
Variable resistor, 20... Comparator, 24...
... Photoisolator, 31 ... Curved thyristor, 36
...Fan motor.

Claims (1)

[Scope of utility model registration request] A circuit that changes the time constant when charging a capacitor using a variable resistor and detects the terminal voltage of this capacitor using a comparator, and an oscillation circuit that consists of multiple resistors, separate capacitors, and a voltage comparator are connected via transistors. The former capacitor is connected to the fan motor, and the alternating current flowing through the fan motor is rectified, and the rectified current is controlled by a thyristor, and the output of the comparator controls the thyristor through a separate transistor and a photoisolator. A forced draft heater characterized by comprising an electric circuit configured to vary the energization time of a motor.