JPH04203733A - Control device for automatic change-over of cooling/ heating in air conditioner - Google Patents

Abstract

PURPOSE:To control room temperature with the same preset value even if there exist fluctuations in cooling/heating load, such as change in the open air by time-keeping the time when the room temperature drops below a specified temperature in cooling mode, and the time when the room temperature exceeds the specified temperature In heating mode and outputting cooling/heating transfer. CONSTITUTION:Cooling load is decreased due to a drop In the open air or the like and room temperature Ta fails to rise even when a compressor comes to a halt at a preset low limit value T2. When elapsed time t from the shutdown of the compressor exceeds transition prohibition time ts and reaches transition setting time tL, a microcomputer 14 generates output to a transistor 20 so as to drive a four way valve relay 17 so that the four way valve may be turned ON. When a refrigeration cycle for heating service is formed, the compressor starts and changes over its operation to heating mode, thereby raising the room temperature Ta. When the room temperature Ta exceeds a preset upper limit value T1 in heating mode, the compressor and the four way valve are halted. The room temperature Ta is kept between the preset values T1 and T2 in a similar manner to cooling operation when the temperature drops to the lower limit value T2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an automatic heating/cooling switching control device for an air conditioner that automatically switches between heating and cooling operation of an air conditioner used to maintain a constant room temperature throughout the year. It is something.

Conventional technology This type of air conditioner has been developed in the past, for example, in Japanese Patent Application Laid-Open No. 58-060.
As shown in Japanese Patent No. 150, a dual thermostat was used. That is, as shown in FIG.
When the set value of the room temperature is set to 5 notches, there are three set values, T1 is the cooling ON point, T2 is the cooling OFF point and heating OFF point, and T3 is the heating ON point. Therefore, usually
When the load is large, cooling operation is performed by stepping between 'rl and T2, and when the load is small and the room temperature drops to T3, it shifts to heating operation, and heating is turned on and off between T3 and 12. Ta.

Problems to be Solved by the Invention However, with this kind of control, the room temperature during cooling operation is Tl.
and T2 is quiet, and during heating it is between T2 and T13, and there is a difference in room temperature between cooling and heating, making it impossible to keep the room temperature constant throughout the year.

Also, if T2 is brought closer to T1 and T3 is closer to T2, the difference in heating and cooling will become smaller, or in this case, the undershoot when the air conditioner is turned off and the overshoot when the heating is turned off and on will cause the heating and cooling to become inverted, resulting in unnecessary heating or heating. During cooling operation, there is a risk that the room temperature will fluctuate rapidly, causing hunting in the air conditioner's cooling and heating operations, which may lead to malfunction.

It is an object of the present invention to solve the problems of such conventional automatic air conditioning/heating switching control devices for air conditioners.

Means for Solving the Problems The present invention provides a room temperature detection means for detecting an indoor temperature Ta, a temperature setting means for setting an upper limit value TI and a lower limit value T2 of the room temperature, and a room temperature detected by the room temperature detection means and the temperature. Comparing means for comparing the temperature set by the setting means and outputting a control signal corresponding to the result, and determining from the comparison result that the room temperature Ta is below the set lower limit 1a T2 during cooling operation, or during heating operation. a timer for measuring the time t which exceeds the set upper limit value T1;
a heating/cooling transition determination means that outputs an output for transitioning from cooling to heating or from heating to cooling when the temperature reaches l−, a storage means that stores a preset cooling or heating operating mode, and a comparison result of the comparison means. This is an automatic heating/cooling switching control device for an air conditioner, which is based on the present invention and is equipped with an indoor feeder, a compressor, an output means for driving a four-way valve, etc.

For example, when the room temperature Ta is between T2 and T1 and the cooling operation is in progress, the room temperature Ta gradually decreases until it reaches T2, and the compressor stops and starts timing at the same time. Normally, there is a slight undershoot, and the room temperature Ta is reached before the set time T L is reached.
begins to reach an upper limit, exceeds T2 and reaches T1, the compressor starts operating again, and the room temperature Ta begins to fall.

Normally, this is repeated and cooling operation is performed between 1 and 12.

However, the cooling load decreases (for example, due to a decrease in outside temperature)
However, even if the room temperature 'a reaches T2 and the compressor stops, the room temperature Ta does not rise easily, and the elapsed time t after reaching T2
is the set value t1. When it reaches , it shifts from cooling to heating operation,
The four-way valve operates to form a refrigeration cycle on the heating side and operate the compressor. As a result, the room temperature Ta rises, and
When T1 is reached, the compressor stops and time measurement begins.

Normally, after a slight overshoot, the room temperature drops before reaching the set time Ta, passes through TI, reaches '2', the compressor operates again, and the room temperature Ta rises.

In this way, the heating operation is performed so that the room temperature Ta is approximately at the leap between TI and T2.

In addition, the negative effect of heating decreases (for example, an increase in outside air temperature), and even if Ta reaches TI and the compressor stops, the room temperature does not fall easily, and the elapsed time after reaching T1 is the set value t,
When reaching L, the heating operation is shifted to the cooling operation, and the cooling operation as described above is performed.

As described above, even if the heating and cooling load changes, the cooling mode is automatically switched, and the room temperature can be kept almost constant between TI and T2 throughout the year.

Example Embodiments of the present invention will be described below based on the drawings.

Fig. 2 is an electrical circuit diagram of the control device, and 3 is a power transformer, which generates a low voltage for the control circuit from the AC commercial power supply applied via the power plug L and the power switch 2. The rectifier 4 converts it to direct current, the capacitor 6 smoothes it, and the indoor blower relay 15, the compressor relay 16,
It is connected to the coil of the four-way valve relay 17.

On the other hand, the constant voltage IC 5 is branched to create a constant voltage wire for other electronic circuits. A capacitor 7 is provided for smoothing a constant voltage wire for an electronic circuit, 14 is a microcomputer (hereinafter referred to as microcomputer), and 8 is an operation stop switch.

A thermistor 9, a variable resistor 101, an oscillator 11, and an oscillation capacitor 12.13 are connected to the microcomputer power boat, and a relay 1 is connected to the output boat via a resistor.
5.16.17 Drive transistor 18.19.20
is connected. 21 to 31 are resistors.

FIG. 1 is a functional block diagram of a control device of the present invention,
Corresponding to the electric circuit in FIG. 2, the room temperature detection means 51 is a thermistor 9, the temperature setting means 52 is a variable resistor 10, and the output means 57 is a transistor 18 to 20 and a relay 1.
Corresponds to 5 to 17.

Furthermore, the clocking means 54 includes an oscillator 11 and an oscillation capacitor 1.
2.13, it is realized in software by the program in the microcomputer 14, and the comparison means 53, the cooling/heating transition determination means 55, and the storage means 56 are also realized in software by the program in the microcomputer 4. will be realized.

Next, the operation of the above embodiment will be explained with reference to the flowchart shown in FIG.

When the operation stop switch 8 is pressed, a signal to that effect is output from the microcomputer 14 to the transistor 18, and the indoor fan relay 15 operates to turn on the indoor fan I! 58
(St. 7th Street).

Next, the room temperature Ta detected by the thermistor 9 is variable @ resistor 1
0 (step S2), the four-way valve is OFF (step S2).
ll), immediately ζko my J:ノ■4 or 1'.

An output is output to the transistor 19, the compressor relay 16 is operated, and cooling operation is started (step 510). As a result, the room temperature Ta falls below the set upper limit Tl, and then the set lower limit ll! Step S2.
S3), if it is higher than Tl (step S3), the current state is maintained and the cooling operation is continued.

Then, when the room temperature Ta gradually decreases and reaches the set lower limit value T2 (step S3), the four-way valve is not ON (step S4), so the output to the transistor 19 of the microcomputer 14 disappears, and the compressor The sushi-16 is restored and the compressor is stopped (step S5). Start timing at the same time. Immediately after, of course the time is smaller than the set time (
Step S6), count up (Step S8)
, the process returns to temperature comparison step S2. Eventually, the time will reach the set time ts, but in normal cases, due to the compressor stopping,
The room temperature Ta gradually rises and before reaching the set time t (
Step S7), the room temperature Ta exceeds the set lower limit T2, and timekeeping is stopped (Step S3).

When the room temperature Ta further rises and goes around the set upper limit value TI by -L, (
In step S2), since the four-way valve is OFF, the compressor is immediately operated (step S5IO).

In this way, the compressor repeatedly stops operating between the temperature set values TI and Tl, and the room temperature Ta is maintained approximately between Tl and Tl.

From this state, the cooling load decreases due to a drop in the outside air temperature, and even if the compressor stops at the set lower limit value T2, the room temperature Ta does not rise, and the transition prohibition time ts occurs after the compressor stops.
step S7), and reaches the transition set time tL.
When the output is output from the microcomputer 14 to the transistor 20 and the four-way valve relay 17 is activated, the four-way valve is turned on (step S9) and a heating refrigeration cycle is formed, the compressor is operated and the heating operation is switched. , the room temperature Ta is increased.

The heating operation starts when the room temperature Ta reaches the set upper limit value T1 (step S2), and the compressor and four-way valve are stopped (step S12). S13, S14, 515°5I6), lower limit T
Steps S3, S4. S9,
5IO), the room temperature Ta is the set value TI and Tl as in the case of cooling.
It is approximately maintained between

In addition, even if the heating load decreases (e.g. due to an increase in outside air temperature) and the room temperature Ta reaches the set upper limit value TI (step S2), the compressor and four-way valve stop (steps Sll, S12, etc.).
513), if not lowered, the elapsed time t from the compressor stop exceeds the transition prohibition time ts and reaches the transition set time ↑, L (step S14.515).
, the compressor does not operate with the four-way valve OFF.Step 5I
O), Run the cooling operation to lower the room temperature Ta.

In addition, mtL at the time of air conditioning transition setting is, if the air conditioning load is small, the elapsed time tK of the leap between the set temperature T1 and Tl will be short, and the undershoot or overshoot after the compressor stops will be large, so LL is also It is desirable to make it short, and conversely, if tK becomes long, tL should also be made long. The values of one example are shown in FIG. That is, for example, when cooling is operated when the cooling load is small (for example, the outside temperature is low), the rate of decline of the room temperature Ta is fast and the time from the set value Tl to Tl is short, and even if the compressor is stopped at Tl, the Since the chute becomes large, in this case, the cooling/heating shift setting time TL is set to be shorter than the prohibition time TS for preventing hunting (step 56.814), and the heating operation is shifted to early. Conversely, when the cooling load is large, the set value T of the room temperature Ta
Since the time from I to Tl is long and there is little need for heating, TL is set to be long.

The same applies to heating operation; when the time from Tl to Tl is short, the set time TL is shortened, and when it is long, TL is changed for a long time, thereby reducing unnecessary cooling/heating transitions and increasing the room temperature between TI and Tl. be able to control between.

Effects of the Invention The present invention provides that during cooling, the time during which room temperature Ta is below Tl,
During heating, the time when the TI exceeds TI is measured and output is output for shifting to cooling/heating, so even if there are fluctuations in the heating/cooling load such as changes in outside air temperature, the room temperature can be controlled at the same set value, and it can be used almost throughout the year, such as in a computer room. Automatic cooling/heating switching for air conditioners is ideal for applications where you want to maintain the same room temperature, or where you want to keep the room temperature almost constant in places such as the Middle East where there is a large difference in outside temperature between daytime and nighttime. A control device is provided.

Furthermore, since the cooling/heating transition set time is changed according to the magnitude of the cooling/heating load, overshoot or undershoot at the time of cooling/heating transition can be minimized, and a room temperature closer to the set value can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of an automatic heating/cooling switching control device for an air conditioner according to the present invention, FIG. 2 is an electric circuit diagram of the embodiment, and FIG. 3 is a flowchart showing the operation of the embodiment. FIG. 4 is a classification time diagram showing types of air-conditioning/heating transition setting time in the same embodiment, and FIG. 5 is a temperature setting diagram in the conventional example. 9...Thermistor, 10...Variable resistor, ]1...
・Oscillator, 12.13...Oscillation capacitor, 1-4
...Microcomputer, 18-20...-Transistor, 15...Relay for indoor blower, I6...Relay for compressor, 17...Relay for four-way valve, 51...
Room temperature detection means, 52... Temperature setting means, 53... Comparison means, 54... Timing means, 55... Cooling/heating transition determination means, 56... Storage means, 57... Output means,
58... Indoor blower, 59... Compressor, 60...
・Four-way valve. Agent Patent Attorney Matsu 1) Tadashi Michi Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) A room temperature detection means for detecting the indoor temperature Ta, a temperature setting means for setting an upper limit value T1 and a lower limit value T2 of the room temperature, and a room temperature detected by the room temperature detection means and a temperature set by the temperature setting means. a comparison means for comparing and outputting a control signal corresponding to the comparison result; and from the comparison result, the room temperature Ta is below a set lower limit value T2 during cooling operation;
Or, a timing means for counting the time t during which the heating operation exceeds the set upper limit value T1, and a time t that is a shift prohibition time t.
s and reaches a set time TL, a heating/cooling transition determination means that outputs an output for transitioning from cooling to heating or from heating to cooling, and a storage means that stores a preset cooling or heating operation mode; An automatic heating/cooling switching control device for an air conditioner, comprising: an output means for driving an indoor blower, a compressor, a four-way valve, etc. based on the comparison result of the comparison means. (2) The set time tL of the cooling/heating transition determination means is the length of time required for the room temperature Ta to reach from the set upper limit T1 to the lower limit T2 during cooling, and from the lower limit T2 to the upper limit T1 during heating. 2. The automatic heating/cooling switching control device for an air conditioner according to claim 1, wherein the automatic switching control device is configured to change in the same trend.