JPS637291B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a blower speed control device for an air conditioner.

Generally, a control device for an air conditioner needs to vary the rotational speed of an AC motor for a blower, which is a load, and methods using thyristors or triaxes have been widely known as methods for controlling this AC load. However, as shown in FIG. 1, the load voltage waveform has large waveform distortion and contains a large amount of high frequency components, which may cause vibrations of the motor, magnetic sound, electromagnetic sound, etc. The conventional solution to this problem was to make the motor case out of casting.
In recent years, due to the reduction in cost and weight of electric motors, the cases mentioned above are often made of sheet metal or plastic, which eliminates the vibrations mentioned above.
The drawback is that it easily generates magnetic and electromagnetic noise.

This invention was made to eliminate the above-mentioned drawbacks, and by using a new control means for controlling AC loads such as AC motors, it is possible to eliminate vibrations, magnetic sounds, and electromagnetic sounds, and at a given environmental temperature. An object of the present invention is to provide a blower speed control device for an air conditioner that can save energy by controlling the rotation speed of the blower or stopping its operation by detecting deviations between the temperature and the set temperature.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIGS. 2 and 3 are block diagrams and detailed circuit diagrams showing one embodiment of the present invention.
is a temperature sensor such as a thermistor that detects room temperature, 2
A, 2b, and 2c are three-pole, double-throw changeover switches that switch between cooling and heating, and 3 is a DC power supply, which constitutes a stabilized power supply with a rectifier and smoothing circuit (not shown) that rectifies and smoothes the AC power supply current, a Zener diode, etc. This is what I got. 4 is a variable resistor, which allows the customer to arbitrarily vary the set temperature. 5 is a semi-fixed resistor, and when the resistance value of the thermistor 1, that is, the room temperature reaches the set temperature for any set temperature of the variable resistor 4, the changeover switch 2 is switched to cold and warm respectively. Since the voltages applied to the blower are set in advance so that the potentials at the connection branch point between the thermistor 1 and the semi-fixed resistor 5 remain the same, the voltages applied to the blower become equal. 6 is an amplifier circuit whose output increases when the input potential decreases, and conversely, when the input potential increases, the output decreases.
7 and 8 are diodes, 9 is the lowest voltage setting circuit, 1
0 is a maximum voltage setting circuit, which limits the anode side potentials of the diodes 7 and 8 to within the set minimum voltage and maximum voltage, respectively. Reference numeral 13 denotes a comparison circuit, the potential of one input point A of which is higher than the potential of the minimum voltage setting circuit 9, lower than the potential of the maximum voltage setting circuit 10, and the indoor temperature detected by the thermistor 1. A considerable potential is supplied. 14 is a reactor circuit, inside which are first saturable reactors 14 each having the same characteristics.
a and a second saturable reactor 14b, the control side winding is connected in series between the end of one winding and the start of the other, and the load side winding is connected between the end of one winding and the other. The winding end side is connected to the winding end side, and the winding start side is connected to the blower 15 which is a load and the AC power supply 1.
Connect in series with 6. Further, the number of windings on the control side is several times larger than the number of windings on the load side, and the configuration is such that a small current change on the control side produces a large current change on the load side. Note that the reactors 14a and 14b are constructed so as to cancel out the generated voltages with each other by the above-described load side winding connection method so as not to generate high voltage on the control side.

17 is a stop circuit, which is equipped with an IC (not shown) and a relay inside, and is configured so that when the input potential rises, the output potential of the IC rises and turns on the relay.
The normally closed contact 18 of this relay is the reactor circuit 1
4. It is connected in series to the blower motor 15 and AC power source 16. In addition, when the indoor temperature for heating and cooling is lowered by an arbitrary temperature than the set temperature, the relay of this stop circuit 17 is set in advance to turn on, and a hysteresis effect is applied to the ON/OFF operating temperature of this relay. I'll keep it. Reference numeral 19 denotes a constant current feedback circuit, which detects the current flowing through the control side windings of the reactors 14a and 14b.
It is fed back to the other input terminal of the .

Based on the above configuration, the operation of an embodiment of the present invention will be explained with reference to the drawings.

Now, considering the case of cooling, when the indoor temperature is very high compared to the set temperature, the resistance value of the thermistor 1 is small and the input potential of the amplifier circuit 6 is also low.As a result, the output potential of the amplifier circuit 6 is high. , the potential set by the highest voltage setting circuit 10 is supplied to one input point A of the comparator circuit 13, and its output potential is supplied to the reactor circuit 14. Then, since the reactors 14a and 14b approach a saturated state, their load-side impedance decreases, the blower 15 rotates at the highest voltage, and air cooling is rapidly performed. Then, when the room temperature falls, the potential detected by the thermistor 1 starts to rise, and the potential supplied to the reactor circuit 14 via the amplifier circuit 6 and comparator circuit 13 starts to drop, causing both the reactors to 14
Since a and 14b approach a non-saturated state, the rotational speed of the blower 15 begins to decrease. When the indoor temperature eventually reaches the set temperature, the low voltage set by the minimum voltage setting circuit 9 is supplied to the reactor circuit 14 via the comparison circuit 13, so the rotation speed of the blower 15 is operated at the minimum rotation speed. . Furthermore, if the indoor temperature drops below the set temperature by an arbitrary temperature set by the stop circuit 17, the stop circuit 1
A relay provided inside the air blower 7 is turned on, and the normally closed contact 18 of this relay stops the operation of the blower 15. After that, the indoor temperature is reduced again to the stop circuit 17.
When the temperature rises by the amount of hysteresis set in , the blower 15 starts operating at the lowest voltage, and the same operation is repeated thereafter. In addition, in the case of heating, the connection of the thermistor 1 that detects the indoor temperature is switched by the changeover switch 2, so the minimum voltage, maximum voltage, stop temperature, hysteresis temperature width, etc. applied to the blower 15 are the same, but the indoor The voltage change characteristics of the blower 15 with respect to temperature are completely opposite. Furthermore, when the indoor temperature reaches the set temperature, the semi-fixed resistor 5 is set in advance so that the voltage applied to the blower 15 remains the same even if the changeover switch 2 is changed, as shown in FIG. Like a blower 15
voltage change characteristics can be obtained. Further, since a saturable reactor is used, the voltage waveform applied to the blower 15 is as shown in FIG. 5. That is, due to the effect of the saturable reactor, when the blower voltage is large, the waveform becomes a sine wave that is almost similar to the power supply voltage waveform. Also, when the blower voltage is low, the waveform will contain some waveform distortion, but this is low-frequency distortion and not the high-frequency waveform distortion that occurs when controlling with a conventional triax or thyristor. It can prevent noise, magnetic noise, and electromagnetic noise.

Also, during energized operation, reactors 14a and 14b
A large current from the blower motor 15 flows through the load side winding of the reactor, and the impedance of the reactor body decreases due to heat generation, so the thermistor 1 detects the room temperature and the potential supplied to one input point A of the comparator circuit changes. Even if it is constant, the set voltage of the blower 15 may vary. In one embodiment of the present invention, by providing a constant current feedback circuit 19,
When the current flowing through the control side windings of the reactors 14a and 14b increases, an increase in potential due to the increase in current is detected and fed back to the other input terminal of the comparison circuit 13,
By lowering the output potential of the comparator circuit 13, a constant current can always flow through the control side windings of the reactors 14a and 14b, and as a result,
Even during long-time energized operation, fluctuations in the set voltage of the blower 15 due to heat generation in the reactor can be prevented.

As explained above, according to the present invention, problems such as vibration, magnetic noise, electromagnetic noise, etc. of the blower can be solved, the rotation speed of the blower can be automatically varied or stopped depending on the predetermined environmental temperature, and wasteful energy can be avoided. Energy saving can be achieved without using
Furthermore, it has a great practical effect of being able to prevent fluctuations in the set voltage of the blower due to heat generation in the reactor.

[Brief explanation of the drawing]

Fig. 1 is a voltage waveform diagram showing the blower voltage of a conventional air conditioner, Figs. 2 and 3 are a block diagram and detailed circuit diagram showing an embodiment of the present invention, and Fig. FIG. 5 is an operating characteristic diagram showing an embodiment of the invention, and is a diagram corresponding to FIG. 1 showing an embodiment of the invention. 1...Thermistor, 6...Amplification circuit, 9...Minimum voltage setting circuit, 10...Maximum voltage setting circuit, 1
3... Comparison circuit, 14... Reactor circuit, 15
...Blower, 17...Stop circuit, 19...Constant current feedback circuit. In addition, in the drawings, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1 a blower, a switching means for switching between cooling and heating, and a first
temperature control means; temperature detection means for detecting the predetermined environmental temperature; and when the temperature detection means detects the predetermined environmental temperature reaching the preset temperature set in advance by the first temperature control means; a second temperature control means set so that the potential at the connection point with the temperature detection means remains equal even if the switching means is switched; an amplifier circuit into which the potential at the connection point is input; and the amplification circuit. A maximum voltage setting circuit that sets the maximum voltage and a minimum voltage setting circuit that sets the minimum voltage connected to the output of the circuit, and the amplifier circuit that corresponds to the predetermined environmental temperature within the voltage range of the maximum voltage and the minimum voltage. A comparison circuit that compares the output voltage of the above with a preset reference voltage and outputs an output according to the deviation, a saturation reactor circuit that inputs the output of the above comparison circuit, and turns on the above blower according to the potential of the above connection point. - A stop circuit that performs off control and has hysteresis characteristics in its on/off operating temperature, and a constant current circuit that detects the current flowing in the control side winding of the saturation reactor circuit and feeds it back as a reference voltage for the comparison circuit. A blower speed control device for an air conditioner, comprising: