JPS5896935A - Control circuit for air conditioner - Google Patents

Abstract

PURPOSE:To enable to perform a comfortable heating, by a method wherein, in a subject circuit provided with a room temperature thermostat circuit for controlling turning-ON and OFF of a compressor, a blower is operated in synchronism with start and stop of the compressor, and when a room temperature thermostat is OFF, the operation of the compressor and the blower are controlled by a period timer. CONSTITUTION:In case a heating side is selected by bringing a cooling/heating change-over switch 21 into ON, if an operation switch 20 is brought to ON, a blower 9 and a 4-way valve 10 for change-over of cooling and heating are turned ON to start a heating. In which case, if a switch for a control circuit 22 is ON, room temperature rises due to heating, and when an output of a comparator 27 for comparing room temperature with a set temperature inverses, a compressor 8 stops operating by means of a microcomputer 18, and the blower 9 stops operating tens seconds later. When in the above condition or a thermostat circuit including the comparator 27 is OFF, the compressor 8 and the blower 9 are controlled by a period timer, not shown, and this realizes a comfortable heating without a cold air feeling.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control circuit for a heat pump type air conditioner, and is particularly intended to improve comfort during heating operation.

The general method of controlling room temperature during heating operation of conventional heat pump air conditioners is to keep the indoor blower running continuously and control the room temperature by turning the compressor on and off depending on the room temperature. Met. In that case, when the compressor is ON and O
The temperature of the air blown out from the indoor fan changes greatly depending on when it is FF, and when it is ON it is 40° to 50℃, and when it is OFF it is room temperature +
α degree), when the compressor was turned off, a cold air sensation was felt, which was not comfortable.

First of all, there is a way to solve this problem.

When the compressor is turned off, the rotation speed of the indoor fan can be lowered a little to reduce the amount of air being blown and to soften the feeling of cold air.Another method is to change the direction of the variable air direction louver at the outlet so that it is horizontal when the compressor is turned off. Practical methods have been put into practice, such as blowing air in a direction to prevent the wind from hitting people directly, and moving the louvers so that when the compressor is turned on, it automatically blows the air downward. However, no matter which method is used, the air circulates inside the room, so a feeling of cold air can be felt when the compressor is turned off, especially when the outside temperature is low.

Therefore, the present invention provides a control circuit for an air conditioner that completely eliminates the feeling of cold air when the compressor is turned off.

Basically, the indoor blower is turned off when the compressor is turned off.
However, if the compressor is simply linked to the compressor, there is a risk that the room temperature cannot be accurately controlled. To explain the reason for this, first, the internal structure of the indoor unit is as shown in Figure 1, where 1 is the main body, 2 is the suction port, and 3 is a thermistor for detecting room temperature, which is installed in the space between the heat exchanger 4 and the suction port 2. It is being Reference numeral 5 denotes a fan for blowing air, which sucks indoor air from an inlet 2 through a heat exchanger 4 and blows it out from an outlet 6 for air conditioning. In such a structure, the thermostat reaches the set value during heating operation and the compressor is stopped. However, when comparing the case where the indoor ventilation fan 5 is stopped at the same time and the case where it is not stopped, the temperature of the room temperature detection thermistor 3 is If the temperatures are significantly different as shown in FIG. 2 and the indoor blower fan 5 is stopped at the same time as the compressor, accurate room temperature detection may not be possible, and room temperature control may not be possible.

To explain this figure 2, the X-axis shows the passage of time, the Y-axis shows the temperature of the room temperature detection thermistor part, and the temperature change of the room temperature detection thermistor part after the thermostat operates is measured by stopping the indoor ventilation fan as before. A broken line indicates a case in which this is not done, and a solid line indicates a case in which the indoor fan motor is stopped at the same time as the thermostand operates and the compressor stops.

First, at point A, the thermistor temperature reaches point B, which is the OFF point, the compressor stops, and if the indoor fan is not stopped, the temperature gradually decreases as shown by the broken line, and after T1 hours, the temperature reaches the ON point, which is the point C. 1 When performing normal room temperature control, the compressor is turned on at this point, but if the indoor ventilation fan is stopped at the same time, as shown by the solid line, if the compressor and indoor ventilation fan are stopped at the same time, the heat will be turned on. Due to the influence of preheating in the exchanger, there is an overshoot of about 30 to 60 seconds, and the temperature finally drops to point B.

It takes 12 hours for the thermostat to reach the ON point, which is much longer than the 11 hours mentioned above, making it impossible to accurately detect the room temperature.

Note that this temperature curve varies considerably depending on the heating load conditions, but if the indoor ventilation fan is stopped at the same time as the compressor, at least an overshoot will occur as shown by the solid line, and the temperature drop of the room temperature detection thermistor section will be delayed.

Therefore, in order to reduce the influence of preheating of the heat exchanger as explained in FIG. This will limit the over 7 utes.

This example will be explained with reference to FIG. First, in Figure 3, the broken line indicates a conventional indoor fan that does not stop.

The solid line indicates that the compressor was stopped after a 14-hour delay after it was turned off. As can be seen in Fig. 3, the time it takes for the thermostand to reach its return temperature C is much closer to T3 than 12 in Fig. 2, which is closer to accurate room temperature control, but Tl and T2 The difference varies considerably depending on the load conditions (indoor temperature, thermostat settings, outside temperature, etc.), and it is not possible to accurately control the room temperature under all conditions. According to data under certain limited conditions, if the difference between the room temperature at the start of operation and the thermostat setting is small (4°C), and the outside temperature is 7°C or less, accurate room temperature control is possible. there were. The larger the difference between the room temperature and the thermoset value, and the lower the outside temperature, the closer the room temperature will be to accurate control, but when the outside temperature is high, accurate control will no longer be performed and the room temperature will be a little lower. was there.

The present invention solves the above problems and provides a control circuit for an air conditioner that accurately controls room temperature according to load conditions.

The present invention will be explained below with reference to Figure 4 and below.0 Figure 4 is a circuit diagram showing one embodiment of the control circuit of an air conditioner according to the present invention, and Figures 5 and 6 are the same control circuit. In Figure 4, which is a time chart of the circuit, 7.7' is the power supply, and 8 is the compressor.

9 is a blower, 10 is an electromagnetic four-way valve that switches between cooling and heating,
11 is a relay contact that turns the compressor 8 ON-OFF, and 12 is a relay contact that turns OFF the blower 9.

13 is a relay contact that turns the four-way valve 10 ON-OFF.

14 is a power transformer, 15 is a rectifier circuit, 16 is a positive side of the DC power supply rectified by the rectifier circuit 15, and 17 is a ground side thereof.

18 is a general one-chip microcomputer with internal program ROM and data RAM.

ALU and input ports INI to IN5. Output port OU
, Tl-0UT11, etc., and is driven by an external oscillation circuit 19.

20 to 22 are switches, which are pulled down by a group of resistors 24 and input to large power ports INI to IN3 of the microcomputer 18, respectively. The switch 20 turns the operation ON-OFF, the switch 21 changes between cooling and heating (cooling OFF and heating ON), and the switch 22 turns the control circuit ON-OFF.
Perform off.

25 is a thermistor that detects the room temperature, which is connected in series with the resistor 26, and its partial pressure is input to the + terminal of the condenser 27. 28 is the thermostand setting value (compressor operating point). A resistor 29 is connected in series as a variable volume, and its divided voltage is input as a reference voltage to one side terminal of a comparator 27. 030 is a transistor to which a relay coil 31 is connected, and from the output terminal OUT + of the microcomputer 18. The output signal turns the relay coil 31 ON-OFF and its contact 11 operates.

Similarly, a relay coil 33 is connected to the transistor 32, and a coil 35.corresponding to the relay contact 12 is connected to the transistor 34. Contact point 13 corresponds.

86.88 is a 7-segment LED (common anode type), and each segment is connected to output port 0 of microcontroller 18.
It is connected to seven data lines UT6 to UT11, and each anode common is turned ON-OFF by transistors 37 and 39 controlled from output ports 4 and 5. That is, 7 segment L, ED86°38 is transistor 37
．． 39, that is, output ports 0UT4 and 5 perform two-digit dynamic lighting. This display data is the temperature detected by the thermistor 25.

40-47 is resistance 0 Next, the operation of the above control circuit will be explained.

First, when switch 20 is turned on, switch 21 turns 0N.
- If it is OFF, it will be in heating mode if it is ON.

Output rHJ to output boat 0UT2.0UT8, blower 9. The four-way valve 10 is turned ONL, and then the room temperature is read by the thermo circuit.

The room temperature detection and thermostat circuit consists of a thermistor 25° and a resistor 26. Comparator 271, polyum 28. It is composed of a resistor 29, etc., and when the room temperature rises, the resistance value of the thermistor 25 decreases, and the + side voltage of the comparator 27 increases, and if it becomes higher than the - side, the + side voltage of the comparator 27 increases. , if it becomes higher than the - side, the comparator 27 operates and the output 27a of the comparator 27 becomes rLJ → "old", and the rHJ signal is input to the input port IN4 of the microcomputer 18.0 If the room temperature falls, the opposite operation occurs. , input port IN5
The rLJ signal is input to. r to this human port IN5
When LJ is input, the room temperature is lower than the room temperature set value, so rHJ is output to the output port 0UTI and the compressor 8 is turned on to perform heating operation. If the 0 heating operation continues and the room temperature rises, the controller The converter 27 is reversed and the input capo) IN
rHJ is input to 4.

The compressor 8 is stopped by setting the output port 0UTI to rLJ. Conventionally, the blower 9 was not operated during that time, and when the compressor 8 was stopped as described above, a feeling of cold air was felt.

The feature of the present invention is the operation when the switch 22 is turned on, and this operation will be explained next. If switch 22 is ON, the room temperature is lower than the setting (9) rLJ is input to IN4.
While the compressor 8 is operating after the signal is input, it is the same as usual, but when the room temperature rises and the comparator 27 is inverted, and the rHJ signal is input to the input port IN4, the compressor 8 is stopped. Subsequently, after several tens of seconds (let's say 30 seconds), the output capo-1-0UT2 is set to rLJ, and the blower 9 is stopped to prevent cold air from circulating indoors. However, as mentioned at the beginning, after the blower 8 is stopped, the temperature near the thermistor 25 tends to be a little higher than the temperature of the thermistor 25 because it cannot keep up with the decrease in room temperature. Control is performed in combination with forced operation.

To explain its basic operation using a time chart, Fig. 5 shows that when the room temperature thermostat continues to be OFF (the room temperature is higher than the set value of the thermostat volume 28), the start position is set to the switch 20.
indicates the point in time when the temperature is O'N or when the room temperature thermometer is at 0FFL.

First, Ta is the restart prevention time regulated by the cycle of the compressor 8 and refrigerant, and if the compressor 8 is started before this time, a startup error may occur and the power breaker may trip, so generally Ta is 3. It takes about a minute.

Tg operates forcibly even if the room temperature thermometer is not turned on, rotates the blower 9, and blows air around the thermistor 25 to accurately detect the room temperature.

The forced operation time is always constant at Tg. If this is too long, the room temperature will rise unnecessarily, and if it is too short, there will be problems such as oil returning to the compressor 8.

A typical range is about 1 to 3 degrees.

If the room temperature thermostat is not ONL, force operation T as shown in Figure 5.
2 and the stop time Ta-Tg are repeated, but the stop time Ta-Tg is Ta<Tb<Tc<Td<T.
The relationship is e<Tf<Tg, and the time increases sequentially until the room temperature thermostat is turned on (the increment between each time is equal). Furthermore, a MAX value is determined as Tg, and it is set so that once a certain value is reached, it will not become longer than that. Even if the room temperature is higher than the thermostat set value and heating operation is not necessary, operation T2. Stop T
g, so the Tg is such that the room temperature does not rise in that state.
need to be set to . Roughly speaking, it takes about 8 to 12 minutes. In controlling the blower 9, Ta is the time during which only the blower 9 is operated to cool down the preheated heat exchanger after the compressor 8 reaches 0FFL, which is usually about 20 to 40 seconds. As you can see in Figure 5, after the compressor 8 has stopped, be sure to
The blower 9 is stopped after a delay of a time.

To explain the relationship between the above control and 0N-OFF of the room temperature thermostat, first, at the 0 point, the thermostat is set to 0FFL, forced operation is performed twice, and during the third forced operation, at the 0 point, the room temperature thermostat is set to ONL, Continuous operation continues, and after a while the thermostat reaches 0 point.
FF4. Since the thermostat is OFF after ,'l, forced operation is performed. Ta, Tj, Tk, Tt in this case
For example, if Ta is 3 minutes and the increment is 1 minute, then Ta
= 3 molecules j = 4 molecules k = 5 minutes, and Tk and Te have a certain relationship and are expressed by the formula Tk≧TeO. In other words, when the thermostat is turned off, forced operation is performed to increase the stop time Ta sequentially to Tj and Tk, but when the thermostat turns ONt, the 9th stop time increment is set to O or minus, and the thermostat is set to 0N-. It coincided with the OFF point. It is balanced by the cycle of running and stopping.

Similarly for Tm and Tn, Tm≧Tn.

At point [F], Tp is scheduled to stop for T7) + 1 minute, but at point [F], the thermostat is turned on and heating operation is performed, and at point 0, the thermostat is at 0FFL. In that case as well, Tc+≧Tq.

As described above, the cycle of forced operation and stop is changed sequentially, and the balance is automatically achieved at the 0N-OFF point of the thermostat, so it can automatically respond to differences and sudden changes in load conditions, and achieve accurate control. This allows you to control the room temperature.

FIG. 7 shows a flowchart of the operation in the microcomputer 18, and when club A is set, it is during the period Tg during forced operation.

At the time of reset, T2 ends. When club B is set, during the compressor stop time (minimum restart time) Ta,
At the time of reset, Ta ends. Timer 1 counts the forced operation Tg, and timer 2 counts the minimum restart time Ta of the compressor. In addition, the timer 3 counts the stop time Ta=Tg and counts up to the set value of the contents of RAMA. be. In addition, FIG. 7(b) is a subroutine for "subtraction", and T
If k=TLTm=Tn and T7)=TqO, the broken line route is used, and if Tk>T/, Tm>Tn, Ta>Tq, the process within the frame is performed.

RA　M　For subtraction and addition of the contents of A, respectively.

MIN value = Minimum restart time = Check Ta
Check to make sure it does not become smaller or louder than the MAX value.

As described above, the present invention provides an air conditioner control circuit equipped with a room temperature thermo circuit that compares the room temperature with a set value and controls the compressor on and off using a predetermined differential. According to the present invention, when the room temperature thermostat is turned off, a one-cycle timer is operated, and the compressor and the blower are started and stopped by this cycle timer. Even when the set value is reached, the room temperature can be accurately detected and the user does not feel a cold breeze.

[Brief explanation of drawings]

1 is a cross-sectional structure of an air conditioner; FIGS. 2 and 3 are temperature change curve diagrams; and FIG. 4 is a circuit diagram showing an embodiment of a control circuit for an air conditioner according to the present invention. 5 and 6 are time charts of the same control circuit. FIGS. 7(a) and 7(b) are flowcharts of the operation of the microcomputer in the control circuit of the present invention. 8: Compressor, 9: Blower, 18: Microcomputer, 25: Thermistor, 26: Resistor, 27: Comparator, 28: Volume, 29: Resistor. Agent Patent Attorney Aihiko Fukushi

Claims (1)

[Scope of Claims] 1. In a control circuit for an air conditioner including a room temperature thermo circuit that compares the room temperature with a set value and controls the compressor ON-OFF using a predetermined differential. An air conditioner characterized in that a blower is started and stopped almost in conjunction with the start and stop of a compressor, and a one-cycle timer is operated when a room temperature thermostat is in an OFF state, and the compressor and the blower are started and stopped by this cycle timer. control circuit. 2. The control circuit for an air conditioner according to claim 1, wherein the cycle of the cycle timer continuously changes while the room temperature thermostat continues to be off. 3. The control circuit for an air conditioner according to claim 1 or 2, wherein the minimum OFF time of the periodic timer is set as the minimum restartable time of the compressor. 4. The control circuit for an air conditioner according to claim 1, 2, or 3, wherein the ON time of the periodic timer is set to 1 minute or more and 3 minutes or less.