JPH089574Y2 - Control device for air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a control device for an air conditioner.

(Prior Art) A refrigerant circuit of a conventional air conditioner is shown in FIG.

During the cooling operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 mounted on the outdoor unit A enters the outdoor heat exchanger 3 via the four-way switching valve 2 as shown by the solid arrow, and here, the outdoor fan 4a. , 4b to condense and liquefy by radiating heat to the outside air. This liquid refrigerant enters the indoor unit B through the check valve 5, and is throttled by the throttle 7 to adiabatically expand into a gas-liquid two-phase. Next, the refrigerant enters the indoor heat exchanger 8, where the indoor air blown by the indoor fan 9 is cooled to evaporate and evaporate, and then is again sucked into the compressor 1 via the four-way switching valve 2.

During the heating operation, the four-way switching valve 2 is switched, and the refrigerant discharged from the compressor 1 in accordance with this switching is the four-way switching valve 2, the indoor heat exchanger 8, the throttle 7,
The throttle 6, the outdoor heat exchanger 3, and the four-way switching valve 2 are circulated through the compressor 1 in this order.

10 is a pressure switch, which is an indoor heat exchanger 8 and a four-way switching valve 2
The pressure switch 10 is attached to a refrigerant pipe connecting with and, and turns off when the pressure of the refrigerant detected by the pressure switch 10 exceeds the upper limit set pressure, and turns on when the lower limit set pressure is reached. 11
Is a temperature sensor, which is attached to the discharge pipe of the compressor 1 and detects the temperature of the refrigerant gas discharged from the compressor 1. A temperature sensor 12 is attached to the refrigerant pipe near the outdoor heat exchanger 3 and detects the temperature of the outdoor heat exchanger 3.

FIG. 4 shows an electric control circuit for the outdoor fans 4a and 4b. When the pressure switch 10 is in the ON state shown in the figure and the changeover switch 13 is switched to the position shown in the solid line in the figure, the drive motor 14a of the outdoor fan 4a and the drive motor 14b of the outdoor fan 4b are energized at their Hi taps and are driven at high speed. When it rotates and the changeover switch 13 is switched to the position of the broken line, the drive motor 14a is stopped and the drive motor 14b is energized to its Lo tap to rotate at a low speed.

FIG. 5 shows a control flowchart of the outdoor fans 4a and 4b during the heating operation.

When the heating operation is started, the outdoor fans 4a and 4b both rotate at high speed. Then, when the temperature of the discharged refrigerant gas detected by the temperature sensor 11 becomes equal to or higher than the upper limit set value TD, the changeover switch 13 is switched to the position of the broken line, the outdoor fan 4a stops, and at the same time the outdoor fan 4b rotates at a low speed. As a result, the amount of heat absorbed by the outdoor heat exchanger 3 decreases, and the temperature of the discharged refrigerant gas decreases. When this temperature reaches the lower limit set value TE, the changeover switch 13 is changed to the position indicated by the solid line.
The outdoor fans 4a and 4b both rotate at high speed.

When the heating load is large, stop the outdoor fan 4a,
Even if the outdoor fan 4b is rotated at a low speed, the temperature of the discharged refrigerant gas does not decrease. When the pressure of the discharged refrigerant exceeds the upper limit set pressure in this state, the pressure switch 10 is turned off and both the outdoor fans 4a and 4b are stopped. As a result, when the pressure of the discharged refrigerant drops and reaches the lower limit set pressure, the outdoor fan 4a is kept stopped, but the outdoor fan 4b rotates at a low speed.

(Problems to be Solved by the Invention) In the above conventional air conditioner, when the heating load is large, the outdoor fan 4a is stopped and the outdoor fan 4b is stopped.
Repeats low speed rotation and stop. In this state, the outside air is the sixth
Since it flows as shown in the figure, the frost 15 gradually adheres to the portion of the outdoor heat exchanger 3 that faces the outdoor fan 4a. Then,
The difference between the pressure of the suction refrigerant gas sucked into the compressor 1 and the pressure of the discharge refrigerant gas discharged from the compressor 1,
That is, the pressure ratio increases, the refrigerant circulation amount decreases, and the temperature of the discharged refrigerant gas becomes more difficult to fall. Therefore, the defrost operation is prohibited during the heating high load operation in which the pressure switch 10 is turned off.

(Means for Solving Problems) In view of the above, the present invention intends to prevent frost formation on the outdoor heat exchanger without defrosting operation even during heating high load operation. The temperature switch that detects the high pressure of the refrigerant circuit during heating operation and turns off when it exceeds the upper limit set value and turns on when it decreases to the lower limit set value and the temperature sensor that detects the compressor discharge pipe temperature. In the controller of the air conditioner configured to control the high pressure of the refrigerant circuit and the compressor discharge pipe temperature by adjusting the amount of air blown by the outdoor fan that blows air to the outdoor heat exchanger by the signal from When the ON state of the pressure switch is detected, the air flow rate of the outdoor fan is increased until a predetermined time elapses after the pressure switch is turned on or the temperature of the outdoor heat exchanger reaches or exceeds the set temperature. In the control device of the air conditioner, a control means is provided.

(Operation) Since the present invention has the above configuration, when the ON state of the pressure switch is detected during heating operation, a predetermined time elapses after the ON state of the pressure switch or the temperature of the outdoor heat exchanger is set to the set temperature. Until the above, the amount of air blown by the outdoor fan is maintained at a large level to melt the frost adhering to the outdoor heat exchanger and prevent the low pressure in the refrigerant circuit from rising abnormally.

(Embodiment) One embodiment of the present invention will be specifically described with reference to FIGS. 1 and 2.

A control block diagram is shown in FIG. The discharged refrigerant gas temperature detected by the temperature sensor 11 is input to the deviation calculation means 21 of the control device 20, and is compared with the set temperature set by the temperature setter 22 here. The temperature of the outdoor heat exchanger 3 detected by the temperature sensor 12 is input to the frost detection means 23,
Here, the presence or absence of frost is detected by comparing with the set temperature TR set by the temperature setter 24. Pressure switch open / close detection means for detecting the temperature deviation calculated by the deviation calculation means 21, the detection result of the frost detection means 23, and ON / OFF of the pressure switch 10.
The detection result of 24 and the output of the time measuring means 25 are input to the tap determining means 26 of the outdoor fan, the tap switching method of the outdoor fan is determined here, and this output is output to the changeover switch 13 via the output means 27 and this. Switch.

 A control flow chart is shown in FIG.

When heating operation starts, the outdoor fan
4a and 4b rotate at high speed. Next, it is judged whether or not the time t set in the time measuring means 25 has passed since the pressure switch 10 was returned (ON) in step. If not,
In step, it is determined whether the temperature of the outdoor heat exchanger 3 is equal to or higher than the set temperature TR. In the case of NO, that is, when the outdoor heat exchanger 3 is frosted, the process returns to the step, but in that case, the process proceeds to the step. Also, if YES is determined in the step, the process proceeds to step. In the step, it is judged whether or not the temperature of the discharged refrigerant gas is equal to or higher than the upper limit temperature TD, and if not, the process returns to the step, but in that case, the process proceeds to the step to stop the outdoor fan 4a, and the outdoor fan Rotate 4b at low speed. Next, in step, it is determined whether or not the pressure switch 10 is turned off. In that case, in step, it is determined whether or not the temperature of the discharged refrigerant gas is equal to or lower than the lower limit temperature TE. If not, return to the step, but if yes, return to the step. YE in steps
When it is determined to be S, it is determined whether or not the pressure switch 10 has returned (ON) at the step, and if not, the process proceeds to the step, but if so, the process returns to the step.

After the pressure switch 10 is turned on, the outdoor fan 4
Since a and 4b rotate at high speed, frost formation does not progress, and the attached frost quickly melts. However, if the outdoor fans 4a and 4b are rotated at high speed even after the frost has melted, the low-pressure pressure rises and the power of the compressor 1 increases, so that the discharge refrigerant temperature exceeds the cooling effect of the intake refrigerant on the compressor 1 and the discharge refrigerant temperature increases. Since it rises, the high speed rotation time of the outdoor fans 4a and 4b is limited to the time t set in the time measuring means 25. Since this time t varies depending on the characteristics of the compressor 1, the outdoor heat exchanger 3, and the like, the time for frost to melt varies. Therefore, an experiment is conducted and the time t is determined to be a time during which the frost does not remain unmelted, for example, several minutes. Temperature setter 24
Although the set temperature TR set to 1 differs depending on the mounting location of the sensor 12, the mounting method, etc., the temperature immediately after the frost attached to the outdoor heat exchanger 3 is completely melted, for example, is set to 0 ° C. If the set temperature TR is determined to be high, the outdoor fans 4a and 4b rotate at high speed and the discharged refrigerant gas temperature rises even after the frost has melted, so the set temperature TR needs to be carefully determined.

The refrigerant circuit and the electric control circuit are the same as the conventional ones shown in FIGS. 3 and 4, and the description thereof will be omitted.

(Advantages of the Invention) In the present invention, during heating operation, the amount of air blown by the outdoor fan is kept large until a predetermined time elapses after the pressure switch is turned on or the temperature of the outdoor heat exchanger exceeds the set temperature. By controlling the frost adhered to the outdoor heat exchanger,
If frost adheres, it will be quickly melted. Therefore, since the defrost operation is not required, the feeling of the person in the room is not hindered.

Moreover, since the low-pressure pressure of the refrigerant circuit rises by increasing the blowing amount of the outdoor fan, the refrigerant circulation amount increases,
As a result, the temperature of the discharged refrigerant gas can be lowered.

Also, after the pressure switch is turned on, the period for maintaining the air flow rate of the outdoor fan at a high level is set until the predetermined time elapses or the temperature of the outdoor heat exchanger reaches or exceeds the set temperature. It is possible to prevent an increase in driving power due to an abnormal rise.

Further, the structure is extremely simple, and it can be implemented at a low cost by slightly modifying the conventional one.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a control block diagram and FIG. 2 is a control flow chart.
3 to 6 show an example of a conventional device, FIG. 3 is a refrigerant circuit diagram, FIG. 4 is an electric control circuit diagram of an outdoor fan, FIG. 5 is a control flowchart, and FIG. 6 is an outdoor heat exchange. It is a conceptual diagram which shows the frosting state to a container. Compressor …… 1, outdoor heat exchanger …… 3, throttle ……
6, 7, indoor heat exchanger …… 8, outdoor fan …… 4a, 4b,
Indoor fan …… 9, Pressure switch …… 10, Pressure switch ON / OFF detection means …… 24, Fan control device …… 20

Claims (1)

[Scope of utility model registration request] 1. A pressure switch for detecting a high pressure of a refrigerant circuit during heating operation, which is turned off when the pressure exceeds a set upper limit value, and is turned on when the pressure falls to a set lower limit value, and a temperature for detecting a compressor discharge pipe temperature. In the air conditioner controller that controls the high-pressure pressure of the refrigerant circuit and the compressor discharge pipe temperature by adjusting the air flow rate of the outdoor fan that blows air to the outdoor heat exchanger according to the signal from the sensor, during heating operation. , When the ON of the pressure switch is detected, a means for increasing the air flow rate of the outdoor fan until a predetermined time elapses after the pressure switch is turned on or the temperature of the outdoor heat exchanger reaches a set temperature or more. An air conditioner control device characterized by being provided.