JP2001235238A - Heat pump type air-conditioning system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump type air-conditioning system capable of improving comfortableness in a room by reducing a heat amount to be discharged into the room after a cooling operation is stopped. SOLUTION: An outdoor heat exchanger 4 of the heat pump type air- conditioning system 1 functions as a condenser, while an indoor heat exchanger 7 functions as an evaporator to conduct a cooling operation. The system 1 stops the cooling operation when an indoor temperature becomes a set temperature or lower. In this case, a motor driven expansion valve 5 is closed only for a predetermined time directly after the stop of the cooling operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump air conditioner capable of performing a so-called thermo control for performing a cooling operation and maintaining an indoor temperature near a set temperature.

[0002]

2. Description of the Related Art A heat pump type air conditioner includes a compressor,
An outdoor heat exchanger having an outdoor fan, a motor-operated expansion valve, and a refrigerant circulation circuit formed by connecting an indoor heat exchanger having an indoor fan in series are provided, and a refrigerant cycle is performed in the refrigerant circulation circuit. In addition, air conditioning for indoor cooling and heating is performed. For example, during the cooling operation, the outdoor heat exchanger functions as a condenser while the indoor heat exchanger functions as an evaporator. Also, during heating operation,
The outdoor heat exchanger functions as an evaporator, while the indoor heat exchanger functions as a condenser.

In a general air conditioner, so-called thermo control can be executed. The thermo control is a control for intermittently performing the air-conditioning operation so that the room temperature is maintained near the set temperature. By performing the thermo control, the user does not need to manually turn on / off the air-conditioning operation, so that the usability of the air conditioner is improved and the indoor comfort is also improved.

[0004]

In recent years, highly airtight and highly insulated houses have become widespread, and the sensible heat load has been reduced accordingly. Therefore, when the thermo control is performed in the cooling operation with a small load, the number of times of switching between thermo-on and thermo-off tends to increase. Here, "thermo-on" means during cooling operation, and "thermo-off" means during cooling operation stop.

For example, an outside air temperature of 29 ° C. and a relative temperature of 75%
When the thermo control is performed in the cooling operation in which the set temperature is 26 ° C., the operation such that the thermo on is performed for 3 minutes and the thermo off is performed for 5 minutes is repeatedly performed, and the indoor temperature is around the set temperature of 26 ° C. (For example, 25.5-26
° C). Therefore, the user should feel comfortable, but actually, a phenomenon has occurred in which the user feels uncomfortable. In particular, the user feels uncomfortable when the thermostat is turned off. Therefore, as a result of comparing and analyzing the state of the air conditioner at the time of thermo-on and at the time of thermo-off, the following two causes have been found as causes of user discomfort.

First, the change in the room humidity and the outlet air humidity during the thermo-control is measured. As shown in FIG.
It turned out that it became humidified at the time of cooling thermo-off. FIG.
5 is a graph showing a change in absolute humidity with time, but the absolute humidity can be replaced with a relative humidity. In FIG. 6, a solid line L11 indicates the absolute humidity of room air,
That is, a change in the indoor relative humidity is shown, and a broken line L12 indicates a change in the absolute humidity of the blown air. A period during which the absolute humidity (room relative humidity) of the room air is rising is a thermo-off period, and a period during which the absolute humidity is falling is a thermo-on period. As indicated by the broken line L12, immediately after the switching to the thermo-off, the absolute humidity of the blown air increases instantaneously but rapidly but humidifies.

Therefore, heat (refrigerant) in the refrigerant circuit is
When analyzing the movement of the compressor, both the compressor and the outdoor fan are stopped when the thermostat is turned off, but the electric expansion valve remains at the opening when the thermostat is turned on. Will flow into the indoor heat exchanger. This causes the temperature of the indoor heat exchanger to rise, and this causes a part of the heat of condensation to be released into the room. For example, cooling operation (thermo-on)
Assuming that the condensing pressure at the time is 15 kg / cm ² g, the liquid / gas mixed refrigerant at 40 ° C. flows into the indoor heat exchanger immediately after switching to the thermo-off, and 10 to 15 ° C. during the cooling operation.
Indoor heat exchanger was 26-29.5 ° C (10-1
1 kg / cm ² g). In the cooling operation with a small load, the heat absorption at the time of the thermo-on is 100 to 20.
In contrast to 0 kcal / h, the heat radiation amount at the time of thermo-off is 30 to 40 kcal / time, which is not negligible.

Further, drain water adheres to the indoor heat exchanger. Due to the rise in the temperature of the indoor heat exchanger, the water vapor partial pressure of the drain water becomes 25 to 31 mmhg,
It becomes higher than the water vapor partial pressure of room air at 6 ° C. and a relative temperature of 80%, ie, 20 mmhg. Therefore, if the indoor fan is driven at the rated wind speed, drain water will re-evaporate,
The indoor heat exchanger functions as a humidifier. In order to prevent the re-evaporation of the drain water, the indoor fan is currently driven so as to have a minimum air volume at the time of thermo-off, but the re-evaporation cannot be made zero.

Immediately after switching to thermo-off,
Humid and warm air will blow out into the room,
The indoor temperature and humidity are being raised. This is one of the causes of discomfort at the time of thermo-off.

Next, comparing the driving state of the indoor fan provided in the indoor unit, when the thermo-on is performed, the rated wind speed is 0.3 to 0.1 mm.
While the driving is performed so as to be about 5 m / sec, when the thermo-off is performed, the air velocity is substantially 0.03 m / sec because it is stopped or driven to have the minimum air volume.
Therefore, an increase in the sensible temperature due to a decrease in the wind speed is also one of the causes of discomfort when the thermostat is turned off.

On the other hand, if a reheat dry operation in which the taken indoor air is once cooled and dehumidified, heated again to room temperature, and then blown into the room is performed, only the humidity can be reduced without lowering the room temperature. Comfort can be improved. However, the reheating dry operation is not advantageous from the viewpoint of energy saving because the power consumption is greatly increased to about 3 to 5 times that of the cooling operation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and has as its object to reduce the amount of heat released into a room after the cooling operation is stopped to improve the indoor comfort. It is an object of the present invention to provide a heat pump type air conditioner which can be used.

[0013]

In the heat pump air conditioner of the present invention, the outdoor heat exchanger 4 functions as a condenser while the indoor heat exchanger 7 functions as an evaporator to perform a cooling operation. A heat pump air conditioner for stopping the cooling operation when the room temperature falls below a set temperature, comprising operation control means 13 and 20 for closing the electric expansion valve 5 for a predetermined time immediately after the cooling operation is stopped. And

In the heat pump type air conditioner according to the first aspect, the electric expansion valve 5 for a predetermined time immediately after the cooling operation is stopped.
Is closed, the flow of the high-temperature condensed refrigerant on the outdoor heat exchanger 4 side into the indoor heat exchanger 7 is delayed by a predetermined time. Then, during this predetermined time, the condensed refrigerant is cooled and its temperature is reduced. Therefore, since the condensed refrigerant having a lower temperature flows into the indoor heat exchanger 7 as compared with the conventional case, an increase in the temperature of the indoor heat exchanger 7 is suppressed, and the amount of heat released to the room is reduced. Also, with the decrease in the amount of heat radiation, the indoor heat exchanger 7
The reheating of the drain water adhering to the water is suppressed, and the re-evaporation amount of the drain water is reduced. As a result, an increase in the temperature and humidity in the room after the cooling operation is stopped can be suppressed, so that the indoor comfort can be improved.

Further, in the heat pump type air conditioner according to the second aspect, the operation control means 13 and 20 are provided with the electric expansion valve 5.
Is performed based on a timer or the temperature of the outdoor heat exchanger 4.

In the heat pump air conditioner of the second aspect, the predetermined time for closing the electric expansion valve 5 is determined based on a timer or the temperature of the outdoor heat exchanger 4. In the case of using a timer, the electric expansion valve 5 is closed only for the time until the timer operation by the timer ends. The time set in the timer is the time required for the high-temperature refrigerant to cool to a specific temperature (for example, near the outdoor temperature), and is obtained in advance by calculation, experiment, or the like. On the other hand, when the temperature is based on the temperature of the outdoor heat exchanger 4, the electric expansion valve 5 is closed only for a time until the outdoor heat exchanger 4 is cooled and decreases to a specific temperature (for example, near the outdoor temperature). As described above, when the timer is used, the control is simple, but there is a disadvantage that the cooling of the high-temperature refrigerant may be incomplete. On the other hand, when the temperature is based on the temperature of the outdoor heat exchanger 4, while the cooling of the high-temperature refrigerant can be surely performed,
There is a disadvantage that control is complicated.

Further, in the heat pump type air conditioner according to the third aspect, the operation control means 13 and 20 are connected to the electric expansion valve 5.
Is characterized in that the outdoor fan 3 is driven during the valve closing control.

In the heat pump air conditioner according to the third aspect, the outdoor fan 3 is driven when the electric expansion valve 5 is closed after the cooling operation is stopped. Thus, the high-temperature refrigerant on the outdoor heat exchanger 4 side can be reliably cooled to near the outdoor temperature in a short time.

A heat pump type air conditioner according to a fourth aspect is characterized in that the outdoor fan 3 is driven so as to have a maximum air volume.

In the heat pump type air conditioner of the fourth aspect, the outdoor fan 3 is driven at the maximum air volume to cool the high-temperature refrigerant, so that the cooling can be performed efficiently.

According to a fifth aspect of the present invention, in the heat pump type air conditioner, when the cooling operation is stopped and the temperature of the indoor heat exchanger 7 is lower than the dew point temperature of the indoor air, the operation control means 13 and 20 determine the dew point temperature. , The indoor fan 6 is driven until it reaches

In the heat pump type air conditioner of the fifth aspect, even after the cooling operation is stopped, the high-temperature refrigerant flows into the indoor heat exchanger 7 immediately because the electric expansion valve 5 is closed as described above. When the temperature of the indoor heat exchanger 7 is lower than the dew point temperature of the indoor air, the indoor heat exchanger 7 can function as a dehumidifier, so that the indoor fan 6 is driven to cool and dehumidify the indoor air. Thus, dehumidified cooling air can be supplied to the room for a certain period of time immediately after the cooling operation is stopped (until the temperature of the indoor heat exchanger 7 reaches the dew point temperature of the indoor air). Therefore, even after the cooling operation is stopped, it is possible to drive the indoor fan 6 at the same wind speed as during the cooling operation, thereby preventing an increase in the sensible temperature due to a decrease in the wind speed.
Indoor comfort can be improved.

In the heat pump type air conditioner of the present invention, while the outdoor heat exchanger 4 functions as a condenser, the indoor heat exchanger 7 functions as an evaporator to perform a cooling operation, and the indoor temperature is equal to or lower than a set temperature. Then, in the heat pump air conditioner for stopping the cooling operation, the discharge side 2a and the suction side 2b of the compressor 2 are connected by a pipe 26, and an opening / closing valve 27 is interposed in the pipe 26. The on-off valve 27 is opened for a predetermined time immediately after the operation is stopped.

In the heat pump type air conditioner of the sixth aspect, since the on-off valve 27 is opened for a predetermined time immediately after the cooling operation is stopped, the high-pressure gas refrigerant on the discharge side 2a of the compressor 2 and the low-pressure gas on the suction side 2b are low. The gas refrigerant is mixed and equalized.
As a result, the pressure of the high-pressure gas refrigerant on the side of the outdoor heat exchanger 4 decreases, and the temperature also decreases. Therefore, since the condensed refrigerant having a lower temperature flows into the indoor heat exchanger 7 as compared with the conventional case, an increase in the temperature of the indoor heat exchanger 7 is suppressed, and the amount of heat released to the room is reduced. In addition, reheating of the drain water attached to the indoor heat exchanger 7 is suppressed with a decrease in the amount of heat radiation,
The amount of re-evaporation of drain water decreases. As a result, an increase in the temperature and humidity in the room after the cooling operation is stopped can be suppressed, so that the indoor comfort can be improved.

[0025]

Next, specific embodiments of a heat pump type air conditioner according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram illustrating a schematic configuration of a heat pump air conditioner (hereinafter, simply referred to as an air conditioner) 1 according to an embodiment of the present invention.

The air conditioner 1 has a refrigerant circuit through which the refrigerant can circulate. The refrigerant circuit includes a compressor 2, an outdoor heat exchanger 4 having an outdoor fan 3, an electric expansion valve 5,
An indoor heat exchanger 7 having an indoor fan 6 is connected in series. Specifically, the discharge pipe 2a of the compressor 2
And the suction pipe 2b are connected to a four-way switching valve 8, which has a first gas pipe 9a, an outdoor heat exchanger 4, a first liquid pipe 10a, an electric expansion valve 5, and a second liquid pipe. 10b, the indoor heat exchanger 7, and the second gas pipe 9b are sequentially connected in a ring shape. The outdoor fan 3 is connected to an outdoor fan motor 3a, and the indoor fan 6 is connected to an indoor fan motor 6a.

FIG. 2 is a configuration diagram showing the electrical configuration of the air conditioner 1. The electrical components included in the air conditioner 1 are classified into an indoor electrical component 11 arranged in the indoor unit and an outdoor electrical component 12 arranged in the outdoor unit. The indoor electrical component 11 includes an indoor microcomputer 13, a room temperature thermistor 14, and an indoor heat exchange thermistor 1.
5, including a humidity sensor 16, a power supply 17, a converter 18, an indoor fan motor 6a, and a swing motor 19. The swing motor 19 is a motor that swings a wind direction control plate provided at an air-conditioned air outlet of an indoor unit. The indoor microcomputer 13 includes a room temperature thermistor 14 and an indoor heat exchange thermistor 1.
5. The converter 18 is controlled based on each detection signal from the humidity sensor 16 and the driving power from the power source 17 is
To the indoor fan motor 6a and the swing motor 19 via the.

The outdoor electrical component 12 includes the outdoor microcomputer 2
0, outside temperature thermistor 21, outdoor heat exchange thermistor 22,
It includes a discharge pipe thermistor 23, a power supply 24, a converter 25, a compressor 2, an outdoor fan motor 3a, an electric expansion valve 5, and a four-way switching valve 8. Then, the outdoor microcomputer 20 controls the converter 25 based on each detection signal from the outdoor temperature thermistor 21, the outdoor heat exchange thermistor 22, and the discharge pipe thermistor 23, and drives the drive power from the power supply 24 via the converter 25. To the compressor 2, the outdoor fan motor 3a, the electric expansion valve 5, and the four-way switching valve 8.

The indoor microcomputer 13 and the outdoor microcomputer 20 constitute operation control means, and the microcomputers 13 and 20 are connected by a signal line (not shown). To the operation control means, together with the detection signals from the various thermistors and sensors described above, operation signals from operation means (not shown) are also input,
The operation state of the air conditioner 1 is determined based on the detection signal and the operation signal. The operation state includes start and stop of the air-conditioning operation, switching between the cooling operation and the heating operation, a set temperature, an air volume, and the like. The operation means is realized by an operation panel connected to the indoor microcomputer 13, a remote control device (abbreviated as a remote control), or the like.

In such an air conditioner 1, a cooling operation or a heating operation can be performed based on an instruction from operation means such as a remote controller. When performing the cooling operation, the four-way switching valve 8 is switched in the solid line direction shown in FIG. 1 to flow the refrigerant from the compressor 2 to the outdoor heat exchanger 4, the electric expansion valve 5, and the indoor heat exchanger 7 in order. The outdoor heat exchanger 4 functions as a condenser, and the indoor heat exchanger 7 functions as an evaporator. Then, by discharging the heat absorbed by the indoor heat exchanger 7 to the outside of the room via the refrigerant, the temperature in the room is lowered to perform cooling.

On the other hand, when performing the heating operation, the four-way switching valve 8 is switched in the direction of the dashed line shown in FIG. 1 to circulate the refrigerant in the direction opposite to that in the cooling operation, and the outdoor heat exchanger 4 is evacuated. And the indoor heat exchanger 7 functions as a condenser. Then, by discharging the amount of heat absorbed by the outdoor heat exchanger 4 into the room via the refrigerant, the room temperature is raised to perform heating.

The air conditioner 1 is configured so that thermo control can be performed. The thermo control is a control for intermittently performing the air-conditioning operation so that the room temperature is maintained near the set temperature. FIG. 3 is a flowchart showing a processing procedure of thermo control during the cooling operation.

When the user operates the operation means to instruct the cooling operation, in a step S1, the cooling operation is started. At this time, the operation control means (the indoor microcomputer 13 and the outdoor microcomputer 20) drives the indoor fan 6 and the outdoor fan 3 at a predetermined set number of revolutions, drives the compressor 2 at a predetermined set frequency, and Is set to a predetermined cooling opening.

In the following step S2, various temperatures and humidity are detected. Specifically, the operation control means includes: a room temperature (room temperature) from the room temperature thermistor 14;
5, the temperature of the indoor heat exchanger 7 (indoor heat exchange temperature), the relative humidity of the indoor air from the humidity sensor 16, the outdoor temperature from the outdoor air temperature thermistor 21, and the outdoor heat exchanger 4 from the outdoor heat exchange thermistor 22. Detects the temperature (outdoor heat exchange temperature).

Then, in a step S3, it is determined whether or not the room temperature is lower than the set temperature. If the room temperature is higher than the set temperature, the cooling operation is continued while steps S2 and S3 are performed.
Is repeatedly executed. If the room temperature is equal to or lower than the set temperature, the process proceeds to step S4.

In step S4, the cooling operation is stopped.
Specifically, the operation control means stops the compressor 2. Here, when the compressor 2 is stopped, when the high-temperature condensed refrigerant on the outdoor heat exchanger 4 side flows into the indoor heat exchanger 7 due to the equalization of the refrigerant pressure in the refrigerant circulation circuit, the indoor heat exchanger The temperature of 7 rises, and part of the heat of condensation is released into the room. As a result, the indoor temperature rises, and the relative temperature inside the room also rises due to the re-evaporation of the drain water, which causes a loss of comfort. Therefore, in the present invention, before the refrigerant pressure is equalized, the heat of condensation is released as much as possible to the outside of the chamber.

Specifically, in step S5, the electric expansion valve 5 is set to a fully closed state. Further, the outdoor fan 3 is driven at the maximum rotation speed. By closing the electric expansion valve 5 in this manner, the condensed refrigerant can be prevented from flowing into the indoor heat exchanger 7, so that the condensed refrigerant can be cooled. Further, by driving the outdoor fan 3, the condensed refrigerant can be efficiently cooled.

In step S6, it is determined whether a predetermined condition has been satisfied. The predetermined condition is a time condition or a temperature condition. The time condition is that the timer operation has been completed. The time set in the timer is the time required for the high-temperature refrigerant to cool to near the outdoor temperature, and is obtained in advance by calculation, experiment, or the like. In the present embodiment, it is 30 seconds. On the other hand, the temperature condition is that the temperature of the outdoor heat exchanger 4 (outdoor heat exchange temperature) has dropped to near the outdoor temperature. Since it takes a considerable time for the outdoor heat exchange temperature to decrease to the outdoor temperature, in this embodiment, the outdoor heat exchange temperature ≦ the outdoor temperature + a (a is a positive constant) is set as the temperature condition. If the above predetermined condition is satisfied, step S7
Proceed to.

In step S7, the electric expansion valve 5 is set to be fully open. Further, the outdoor fan 3 is stopped. By opening the electric expansion valve 5 in this manner, the refrigerant pressure in the refrigerant circuit is equalized. At the time of pressure equalization, since the condensed refrigerant is cooled to the vicinity of the outdoor temperature, the temperature rise of the indoor heat exchanger 7 is suppressed, and the amount of heat released indoors is reduced. As a result, an increase in the room temperature is suppressed, and an increase in the relative humidity in the room is suppressed by a decrease in the amount of re-evaporation of the drain water, so that the indoor comfort is improved.

In step S8, the indoor temperature is detected, and it is determined whether or not indoor temperature ≧ set temperature + c (c is a positive constant). If the determination is affirmative, the process returns to step S1, and the cooling operation is started again. The reason for setting the thermo-on start condition to be room temperature ≧ set temperature + c is that if room temperature ≧ set temperature, thermo-on and thermo-off are switched in a very short time.

During steps S5 to S7, steps S11 and S12 are executed as interrupt processing. First, step S11
Then, it is determined whether or not the indoor dew point temperature ≦ the indoor heat exchange temperature + b (b is a positive constant). This is because the sudden rise in temperature of the indoor heat exchanger 7 is suppressed by closing the electric expansion valve 5 as described above, so that it is determined whether or not the indoor heat exchanger 7 can function as a dehumidifier. It is. The indoor dew point temperature is obtained based on the indoor temperature and the relative humidity.

When the determination is negative, that is, when the indoor heat exchanger 7 can function as a dehumidifier, the rotation speed of the indoor fan 6 is maintained as it is during the cooling operation. On the other hand, if the determination is affirmative, that is, if the indoor heat exchanger 7 cannot function as a dehumidifier, the indoor fan 6 is stopped or the LL operation (operation at the minimum rotation speed) is performed in step S12. . This is because the indoor heat exchanger 7 may function as a humidifier.

FIG. 4 is a graph showing changes in the partial pressure of water vapor during thermo control. This graph shows the change when switching from thermo-on to thermo-off for 3 minutes. During the thermo-on period, the condensation side is maintained at about 40 mmhg as indicated by the solid line L1, and the evaporation side is maintained at about 13 mmhg as indicated by the solid line L2.

First, in the conventional case, after being switched to the thermo-off, about 30 seconds later, after being flattened to about 24 mmhg as shown by solid lines L3 and L4, the indoor air pressure is shown by the solid line L5. It changes at a water vapor partial pressure higher than about 19 mmhg.

On the other hand, in the case of the present invention, the electric expansion valve 5 is fully closed for about 30 seconds after switching to thermo-off,
In addition, since the outdoor fan 3 was driven at the maximum number of revolutions, the dashed lines L6, L
About 17mmhg lower than the indoor air pressure as shown by 7
After that, the pressure changes at a water vapor partial pressure lower than the indoor air pressure as shown by a broken line L8. Since the water vapor partial pressure is lower than the indoor air pressure, the re-evaporation of the drain water is suppressed.

As described above, according to the present embodiment, since the condensed refrigerant having a lower temperature than the conventional one flows into the indoor heat exchanger 7, the temperature rise of the indoor heat exchanger 7 is suppressed, and The heat dissipation is reduced. In addition, as the amount of heat radiation decreases, reheating of the drain water attached to the indoor heat exchanger 7 is suppressed, and the amount of re-evaporation of the drain water decreases. As a result, the indoor temperature rise and the humidity rise after the cooling operation is stopped are suppressed, and the indoor comfort is improved.

If the time for closing the electric expansion valve 5 is determined based on a timer, the control is simplified, and the manufacturing cost can be reduced with the simplification of the control circuit. Become. On the other hand, if the time is determined based on the temperature of the outdoor heat exchanger 4, the high-temperature refrigerant can be reliably cooled, so that the improvement in indoor comfort is reliably realized. Therefore, the determination method may be selected depending on whether importance is attached to improvement of comfort or simplification of control.

Further, by driving the outdoor fan 3 while the electric expansion valve 5 is closed, the high-temperature refrigerant on the outdoor heat exchanger side can be reliably cooled to near the outdoor temperature in a short time. Further, since the outdoor fan 3 is driven at the maximum air volume, the high-temperature refrigerant can be efficiently cooled.

Further, since dehumidified cooling air can be supplied to the room for a certain period immediately after the cooling operation is stopped, the indoor fan 6 can be driven at the same wind speed as during the cooling operation even after the cooling operation is stopped. It is possible to prevent an increase in the sensible temperature due to a decrease in the wind speed, and to improve indoor comfort.

Although the specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be implemented with various modifications within the scope of the present invention.

FIG. 5 is a block diagram showing another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIG. 1 above, and the same components are denoted by the same reference characters and detailed description thereof will not be repeated. The present embodiment is characterized in that the discharge pipe 2a and the suction pipe 2b of the compressor 2 are connected by a pipe 26, and a so-called pressure equalizing circuit is formed by interposing an on-off valve 27 in the pipe 26 to perform a cooling operation. Is to open the on-off valve 27 only for a predetermined time immediately after the stop.

In this embodiment, since the on-off valve 27 is opened for a predetermined time immediately after the cooling operation is stopped, the high-pressure gas refrigerant on the discharge side of the compressor 2 and the low-pressure gas refrigerant on the suction side are mixed and evenly distributed. Pressed. As a result, the pressure of the high-pressure gas refrigerant on the side of the outdoor heat exchanger 4 decreases, and the temperature also decreases. Therefore, in the present embodiment, the same effect as in the above-described embodiment can be obtained. In particular, this embodiment is effective when a capillary tube or the like is used instead of the electric expansion valve 5 as the pressure reducing mechanism.

[0053]

As described above, according to the heat pump type air conditioner of the first or sixth aspect, the condensed refrigerant having a lower temperature than the conventional one flows into the indoor heat exchanger. The rise is suppressed, and the amount of heat released into the room decreases. In addition, as the amount of heat radiation decreases, reheating of the drain water attached to the indoor heat exchanger is suppressed, and the amount of re-evaporation of the drain water decreases. As a result, the indoor temperature rise and the humidity rise after the cooling operation is stopped are suppressed, and the indoor comfort is improved.

According to the heat pump type air conditioner of the second aspect, if the predetermined time for closing the electric expansion valve is determined based on the timer, the control becomes simpler and the control circuit becomes simpler. As a result, the manufacturing cost can be reduced. On the other hand, if the predetermined time is determined based on the temperature of the outdoor heat exchanger, the high-temperature refrigerant can be reliably cooled, so that the improvement in indoor comfort can be reliably realized. Therefore, the determination method may be selected depending on whether importance is attached to improvement of comfort or simplification of control.

Further, according to the heat pump type air conditioner of the third aspect, by driving the outdoor fan, the high-temperature refrigerant on the side of the outdoor heat exchanger can be reliably cooled to near the outdoor temperature in a short time.

According to the heat pump type air conditioner of the fourth aspect, since the outdoor fan is driven at the maximum air volume, the high-temperature refrigerant can be efficiently cooled.

According to the heat pump type air conditioner of the fifth aspect, the dehumidified cooling air can be supplied to the room for a certain time immediately after the cooling operation is stopped. It is possible to drive at the wind speed, preventing the rise in the perceived temperature due to the decrease in wind speed,
Indoor comfort can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a schematic configuration of a heat pump air conditioner according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an electrical configuration of the air conditioner.

FIG. 3 is a flowchart showing a processing procedure of thermo control during a cooling operation.

FIG. 4 is a graph showing a change in water vapor partial pressure during thermo control.

FIG. 5 is a configuration diagram showing another embodiment of the present invention.

FIG. 6 is a graph for explaining a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat pump type air conditioner 2 Compressor 2a Discharge pipe 2b Suction pipe 3 Outdoor fan 4 Outdoor heat exchanger 5 Electric expansion valve 6 Indoor fan 7 Indoor heat exchanger 13 Indoor microcomputer 14 Room temperature thermistor 15 Indoor heat exchange thermistor 16 Humidity sensor 20 Outdoor Microcomputer 21 Outside temperature thermistor 22 Outdoor heat exchange thermistor 26 Piping 27 On-off valve

Claims (6)

[Claims] 1. An outdoor heat exchanger (4) functions as a condenser, while an indoor heat exchanger (7) functions as an evaporator to perform a cooling operation. When the indoor temperature falls below a set temperature, the cooling operation is performed. In a heat pump air conditioner for stopping the operation, an operation control means (13) for closing the electric expansion valve (5) for a predetermined time immediately after the stop of the cooling operation.
A heat pump air conditioner comprising (20). 2. The operation control means (13) (20) comprises:
The heat pump type air conditioner according to claim 1, wherein the valve closing control of the electric expansion valve (5) is performed based on a timer or a temperature of the outdoor heat exchanger (4). 3. The operation control means (13), (20)
The heat pump type air conditioner according to claim 1 or 2, wherein the outdoor fan (3) is driven during the valve closing control of the electric expansion valve (5). 4. The heat pump type air conditioner according to claim 3, wherein said outdoor fan is driven to have a maximum air volume. 5. The operation control means (13), (20)
If the temperature of the indoor heat exchanger (7) is lower than the dew point temperature of the indoor air when the cooling operation is stopped, the indoor fan (6) is driven until the dew point temperature is reached. The heat pump air conditioner according to claim 4. 6. The outdoor heat exchanger (4) functions as a condenser, while the indoor heat exchanger (7) functions as an evaporator to perform a cooling operation. In a heat pump type air conditioner for stopping operation, a discharge side (2a) and a suction side (2b) of a compressor (2) are connected by a pipe (26), and an on-off valve (27) is connected to the pipe (26). A heat pump type air conditioner, wherein the on-off valve (27) is opened for a predetermined time immediately after the cooling operation is stopped.