JP2014102019A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable room temperature control by repetition of start or stop of a natural circulation cooling operation, and to smoothly restart the natural circulation cooling operation from a stopped state of the natural circulation cooling operation.SOLUTION: An air conditioner is configured to switchably perform a forced circulation cooling operation for actuating a compressor 1 and forcibly circulating refrigerant and a natural circulation cooling operation for naturally circulating the refrigerant using gravitation by connecting an indoor heat exchanger 4 to an outdoor heat exchanger 2 disposed at a higher position than a position of this indoor heat exchanger via refrigerant pipes 5 and 6. During the natural circulation cooling operation, a temperature of an air-conditioning-target indoor space is controlled by starting or stopping the natural circulation cooling operation by opening or closing an expansion valve 3. During the stop of the natural circulation cooling operation, the expansion valve 3 is fully closed and an outdoor fan 9 is stopped, an indoor fan 10 is actuated for predetermined time after fully closing the expansion valve, and this indoor fan is then stopped.

Description

  The present invention relates to an air conditioner that can be operated by switching between a forced circulation cooling operation and a natural circulation cooling operation.

  The energy depletion problem and global warming problem in recent years have attracted attention, and the energy-saving performance of air conditioners has become more important. On the other hand, the load due to OA equipment and the like is increasing in buildings and offices, and there is an increasing number of cases where cooling is required even in spring and autumn when the outside air temperature is low.

  In such a situation, in order to improve the energy saving performance of the air conditioner, Japanese Patent No. 4167196 (Patent Document 1) proposes an air conditioner that combines natural circulation cooling operation and forced circulation cooling operation. ing. That is, in this patent document 1, when the outside air temperature is low, the compressor is stopped and the natural circulation cooling operation with less power using the circulation of the refrigerant by gravity is performed, and the outside air temperature is high and the load is high. Describes a natural circulation combined type air conditioner that performs a forced circulation cooling operation that operates a compressor.

  Japanese Patent Application Laid-Open No. 2003-289195 (Patent Document 2) discloses a cooling device that cools the inside of a housing of a storage box that contains a device including a heat-generating component, based on the outside air temperature and the inside temperature of the housing. It is described that the operation by the forced circulation system and the operation by the refrigerant natural circulation system are switched. Further, Patent Document 2 also describes that, during the cooling operation by the refrigerant natural circulation system, the opening of the electronic expansion valve is adjusted to adjust the refrigerant flow rate, and the temperature inside the housing is adjusted.

Japanese Patent No. 4167196 JP 2003-289195 A

In the cooling operation by the natural circulation method, when the indoor temperature is controlled, the cooling capacity cannot be actively controlled by controlling the compressor, unlike the cooling operation by the forced circulation method.
The thing of the said patent document 1 is not considered about controlling the indoor temperature in the cooling operation by a natural circulation system.

  Moreover, in the thing of the said patent document 2, at the time of cooling operation by a refrigerant | coolant natural circulation system, adjusting the flow volume of the flowing refrigerant | coolant by adjusting the opening degree of an electronic expansion valve, and controlling cooling capacity is disclosed. Yes. However, during natural circulation cooling operation, in order to control the indoor temperature, the electronic expansion valve is controlled to be fully open or fully closed so that the natural circulation cooling operation is repeatedly started (on) and stopped (off). There is no disclosure of control. In addition, from the state where the expansion valve is fully closed and the natural circulation cooling operation is stopped, when the electronic expansion valve is fully opened and the natural circulation cooling operation is restarted, consideration is given to starting smoothly. Not done.

  An object of the present invention is to provide an air conditioner that enables room temperature control by repeatedly starting and stopping a natural circulation cooling operation, and can smoothly restart the natural circulation cooling operation from a stopped state of the natural circulation cooling operation. There is to get.

  To achieve the above object, the present invention provides a compressor, an outdoor heat exchanger that exchanges heat with outdoor air blown by an outdoor fan, a chamber that exchanges heat with indoor air blown by an expansion valve and an indoor fan. Connect the inner heat exchangers sequentially with refrigerant piping, operate the compressor to forcibly circulate and cool the refrigerant, install the indoor heat exchanger, and a position higher than the indoor heat exchanger The air that can be operated by connecting the outdoor heat exchanger that has been connected by the refrigerant pipe (connection liquid pipe and connection gas pipe) and switching between natural circulation cooling operation that naturally circulates the refrigerant using gravity. In the natural circulation cooling operation, the natural circulation cooling operation is configured to perform temperature control of the indoor space to be air-conditioned by starting and stopping the natural circulation cooling operation by opening and closing the expansion valve, and the natural circulation cooling When the rotation is stopped, the expansion valve is fully closed and the outdoor fan is stopped. Further, after the expansion valve is fully closed, the indoor fan is operated for a predetermined time, and then the indoor fan is stopped. Features.

  According to the present invention, an air conditioner that enables room temperature control by repeatedly starting and stopping a natural circulation cooling operation, and that can smoothly restart the natural circulation cooling operation from a stopped state of the natural circulation cooling operation. There is an effect that can be obtained.

It is a refrigerating cycle block diagram which shows Example 1 of the air conditioner of this invention.

  Hereinafter, specific embodiments of the air conditioner of the present invention will be described with reference to the drawings.

FIG. 1 is a refrigeration cycle configuration diagram showing Embodiment 1 of an air conditioner of the present invention. In FIG. 1, 1 is a compressor constituted by a scroll compressor and the like, 2 is an outdoor heat exchanger that exchanges heat with outdoor air, 3 is an indoor expansion valve that is constituted by an electronic expansion valve, and 4 is an indoor These are indoor heat exchangers that exchange heat with air, and these devices are sequentially connected by refrigerant pipes (connection liquid pipe 5, connection gas pipe 6, etc.). The refrigerant pipe on the suction side and the refrigerant pipe on the discharge side of the compressor 1 are connected by a bypass pipe 7 so as to bypass the compressor 1, and the outdoor heat exchange is connected to the bypass pipe 7. A check valve 8 is provided that allows the refrigerant to flow only to the side of the vessel 2.
An outdoor fan 9 blows outdoor air to the outdoor heat exchanger 2, and an indoor fan 10 blows indoor air to the indoor heat exchanger 4.

  The compressor 1, the outdoor heat exchanger 2, the bypass pipe 7, the check valve 8, the outdoor fan 9, and the like described above are provided in the outdoor unit 100 that is installed outside the room. The inner heat exchanger 4 and the indoor fan 10 are provided in an indoor unit 200 installed indoors. The outdoor unit 100 and the indoor unit 200 are connected by the connection liquid pipe 5 and the connection gas pipe 6, and the outdoor unit 100 is installed at a position higher than the indoor unit 200, for example, on the roof of a building. Yes.

  That is, the air conditioner of this embodiment was installed not only in the forced circulation cooling operation in which the compressor 1 is operated to forcibly circulate the refrigerant, but also in the indoor heat exchanger 4 and a position higher than this. The outdoor heat exchanger 2 is connected by the connection liquid pipe 5 and the connection gas pipe 6, and a natural circulation cooling operation in which the refrigerant is naturally circulated using gravity is possible. The air conditioner can be operated by switching between the forced circulation cooling operation and the natural circulation cooling operation.

  During the forced circulation cooling operation, the refrigerant flows as indicated by the solid black arrows in FIG. That is, the refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 2 installed above, where it is liquefied by exchanging heat with the outdoor air blown by the outdoor fan 9. Thereafter, the liquefied liquid refrigerant flows through the connecting liquid pipe 5, is depressurized by the indoor expansion valve 3, and enters the indoor heat exchanger 4. Here, the refrigerant exchanges heat with the indoor air sent by the indoor fan 10 to cool the air, and also increases (vaporizes) the vapor itself, flows through the connecting gas pipe 6, and is sucked into the compressor 1 again. Repeat the refrigeration cycle.

  During the natural circulation cooling operation, the refrigerant flows as indicated by solid white arrows in the figure. In the natural circulation cooling operation, the compressor 1 is stopped. For this reason, the refrigerant does not flow through the compressor 1, and the gas refrigerant (gaseous refrigerant) from the indoor heat exchanger 4 passes through the bypass pipe 7 and the check valve 8 and the outdoor heat exchanger 2. Flowing into. Further, the indoor expansion valve 3 is fully opened to reduce the flow resistance through which the refrigerant flows as much as possible.

  This natural circulation cooling operation enables efficient operation when the temperature of outdoor air is low and the temperature of indoor air is high. In order to reliably perform this natural circulation cooling operation, it is necessary to ensure that liquid refrigerant flows through the connection liquid pipe 5 and gas refrigerant (gas refrigerant) flows through the connection gas pipe 6 reliably.

  The natural circulation cooling operation is an operation performed by circulating a refrigerant by gravity without having a means for actively controlling the capacity like a compressor. Therefore, the room temperature is controlled as follows. That is, when the indoor temperature falls below the set temperature during the natural circulation cooling operation, for example, when the outdoor fan falls below the set temperature by a slight correction amount of about -0.2K. 9 is stopped and the indoor expansion valve 3 is fully closed to control the cooling capacity not to be generated. Thus, energy consumption can be suppressed by stopping the outdoor fan 9 during the natural circulation cooling operation.

  After the natural circulation cooling operation is stopped, when the indoor temperature becomes equal to or higher than the set temperature, for example, when the outdoor fan 9 is operated at a time when the room temperature further increases by a slight correction amount of about +0.2 K from the set temperature. And the natural expansion cooling operation is restarted by fully opening the indoor expansion valve 3. That is, the refrigerant is naturally circulated again to generate cooling capacity.

  The temperature for stopping the natural circulation cooling operation or restarting the natural circulation cooling operation may be performed at the set temperature. However, when the stop is performed as in the above-described example, the set temperature is negatively corrected. When restarting by adding an amount, by controlling to stop or restart when the temperature reaches a plus correction amount, it is possible to prevent hunting of start and stop, more reliable High air conditioner can be obtained.

  Further, during the natural circulation cooling operation, the refrigerant in the indoor heat exchanger 4 and the flow passage (the refrigerant pipe and the connecting gas pipe 6 in the indoor heat exchanger 4) are cooled. When the natural circulation cooling operation is stopped and the flow of the refrigerant is stopped, the refrigerant in the indoor heat exchanger 4 is condensed and stored, and the refrigerant in the connection gas pipe 6 is also condensed and liquefied. It stays in the middle or backflows in the indoor heat exchanger 4 and accumulates. As described above, if the liquid refrigerant is filled in the indoor heat exchanger 4 or in the middle of the connecting gas pipe 6, the refrigerant cannot be pushed out when the next natural circulation cooling operation is restarted. It becomes difficult to restart the circulation cooling operation.

  Therefore, in this embodiment, when the natural circulation cooling operation is stopped from the state where the natural circulation cooling operation is being performed, the following transition control is performed. That is, first, as described above, the outdoor fan 9 is stopped and the indoor expansion valve 3 is fully closed so that the cooling capacity is not generated. The indoor fan 10 is controlled so as to continue operation for a predetermined time after the indoor expansion valve 3 is fully closed. This predetermined time is preferably set to be longer than the time required to vaporize almost all of the liquid refrigerant in the indoor heat exchanger 4.

By controlling in this way, the temperature of the stopped indoor heat exchanger 4 can be raised. Therefore, even if the natural circulation cooling operation is stopped and the flow of the refrigerant stops, the flow in the indoor heat exchanger The liquid refrigerant can be vaporized, and the refrigerant in the indoor heat exchanger 4 can be prevented from condensing and accumulating. Furthermore, it is possible to prevent the refrigerant in the connection gas pipe 6 from condensing into liquid and staying in the connection gas pipe 6 or flowing back into the indoor heat exchanger 4 and collecting.
Note that, after the predetermined time has elapsed, the indoor fan 10 is also controlled to stop, thereby reducing power consumption.

  When the temperature of the indoor space becomes equal to or higher than a set temperature (in this embodiment, a temperature obtained by adding a positive correction amount) due to the stop of the natural circulation cooling operation, the outdoor fan 9 and the indoor fan 10 are operated. By fully opening the indoor expansion valve 3, the natural circulation cooling operation is restarted and the cooling capacity is generated. Thus, room temperature control can be enabled by repeating the start and stop of the natural circulation cooling operation.

  In the above-described embodiment, when the temperature of the indoor space is lower than the set temperature by a predetermined temperature, the expansion valve is fully closed to stop the natural circulation cooling operation, and the temperature of the indoor space is When the temperature rises higher than the set temperature, the expansion valve is fully opened and the natural circulation cooling operation is restarted to prevent start and stop hunting. However, after the natural circulation cooling operation is stopped, when the temperature rise in the indoor space is slow, a part of the refrigerant liquid in the connection liquid pipe 5 is vaporized (gasified). In particular, the portion 5a of the connection liquid pipe 5 on the upstream side of the indoor expansion valve 3 in the indoor unit 200 is likely to receive heat from high-temperature indoor air and to be easily vaporized. The refrigerant vaporized in the connection liquid pipe 5 becomes bubbles and rises in the connection liquid pipe 5, and in the upper part of the connection liquid pipe 5, particularly in the downstream portion 5 b of the outdoor heat exchanger 2 of the outdoor unit 100. Air bubbles tend to accumulate.

  Thus, when the vaporized refrigerant accumulates in the connection liquid pipe 5, the outdoor fan 9 is operated to condense the refrigerant in the outdoor heat exchanger 2 in order to restart the natural circulation cooling operation. However, it is difficult for the liquid refrigerant to flow through the connection liquid pipe 5 to the indoor heat exchanger 4 side, and it may be difficult to restart.

  Therefore, in the present embodiment, as described above, after the natural circulation cooling operation is stopped, when the room temperature becomes equal to or higher than the set temperature, a slight correction amount, for example, about 0.2K from the set temperature. When the temperature further rises by the amount, the operation of the outdoor fan 9 is started and the indoor expansion valve 3 is fully opened to restart the natural circulation cooling operation.

  In the forced circulation cooling operation, in order to prevent hunting, a correction amount of about ± 1 to 2K is usually taken from the set temperature. In this embodiment, the correction amount is about ± 0.2K (for example, ± 0). In the range of 0.1 to 0.3 K), the stop time of the natural circulation cooling operation can be prevented from becoming too long. For example, the stop time can be preferably 1 to 2 minutes.

  Note that after the indoor expansion valve 3 is fully closed and the natural circulation cooling operation is stopped, the load on the indoor space is small, and even if the temperature does not rise above the set temperature by a predetermined temperature, When a certain time (about 2 to 15 minutes, preferably 2 to 5 minutes) has elapsed after the circulation cooling operation is stopped, the indoor expansion valve 3 is fully opened and the natural circulation cooling operation is restarted. The possibility that the restart becomes difficult can be reduced.

  In this way, an air conditioner that enables the room temperature control by repeating the start and stop of the natural circulation cooling operation, and can smoothly restart the natural circulation cooling operation from the stopped state of the natural circulation cooling operation. Can be obtained.

  In addition, after the natural circulation cooling operation is stopped and the indoor fan 10 is also stopped, the power consumption can be made substantially zero, so that a high COP is maintained and the room temperature is controlled to the set temperature. Natural circulation cooling operation is possible.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, in the above-described embodiment, the example in which the indoor expansion valve 3 is configured by an electronic expansion valve has been described. However, the indoor expansion valve 3 is not limited to the electronic expansion valve, and the natural expansion cooling operation can be performed in the chamber. An expansion valve that can cause liquid refrigerant to flow into or stop the flow into the inner heat exchanger 4 (a combination of a decompression device such as an expansion valve and a bypass circuit having an on-off valve is also included in the concept of the expansion valve. If it is)

  In the above embodiment, the example in which the inflow / stop of the liquid refrigerant during the natural circulation cooling operation is controlled by opening and closing the indoor expansion valve 3 has been described. However, the inflow / stop of the liquid refrigerant during the natural circulation cooling operation has been described. The expansion valve for controlling the stop is not limited to the indoor expansion valve 3. For example, an expansion valve is provided in the connection liquid pipe 5 between the outdoor unit 100 and the indoor unit 200 to control the stop. Also good.

  Further, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

1 ... Compressor,
2 ... Outdoor heat exchanger,
3 ... Indoor expansion valve (expansion valve),
4 ... Indoor heat exchanger,
5 ... Connection liquid piping, 6 ... Connection gas piping,
7 ... Bypass piping, 8 ... Check valve,
9 ... outdoor fan, 10 ... indoor fan.

Claims (5)

Refrigerant piping sequentially connects an outdoor heat exchanger that exchanges heat with the outdoor air blown by the compressor, the outdoor fan, and an indoor heat exchanger that exchanges heat with the indoor air blown by the expansion valve and the indoor fan. , Forced circulation cooling operation in which the compressor is operated to forcibly circulate the refrigerant;
The indoor heat exchanger and the outdoor heat exchanger installed at a position higher than the indoor heat exchanger are connected by the refrigerant pipe, and the refrigerant is naturally circulated using gravity. An air conditioner that can be operated by switching between circulation cooling operation and
The natural circulation cooling operation is configured to control the temperature of the indoor space to be air-conditioned by starting and stopping the natural circulation cooling operation by opening and closing the expansion valve, and when the natural circulation cooling operation is stopped, An air conditioner characterized by fully closing the expansion valve and stopping the outdoor fan, further closing the expansion valve, operating the indoor fan for a predetermined time, and then stopping the indoor fan. .   2. The air conditioner according to claim 1, wherein, in the natural circulation cooling operation, when the temperature of the indoor space becomes equal to or lower than a set temperature, the expansion valve is fully closed to stop the natural circulation cooling operation. When the temperature of the indoor space is equal to or higher than the set temperature, the natural circulation cooling operation is restarted by fully opening the expansion valve.   3. The air conditioner according to claim 2, wherein when the temperature of the indoor space is lower than the set temperature by a predetermined temperature, the expansion valve is fully closed to stop the natural circulation cooling operation, and the indoor space When the temperature of the air conditioner rises by a predetermined temperature from the set temperature, the natural circulation cooling operation is restarted by fully opening the expansion valve.   4. The air conditioner according to claim 3, wherein after the expansion valve is fully closed and the natural circulation cooling operation is stopped, the temperature of the indoor space is not increased by a predetermined temperature from the set temperature. Even if it exists, the air conditioner characterized by restarting the natural circulation cooling operation by fully opening the expansion valve when a certain time has elapsed after the natural circulation cooling operation is stopped.   2. The air conditioner according to claim 1, wherein after the expansion valve is fully closed, the predetermined time for operating the indoor fan vaporizes the liquid refrigerant in the indoor heat exchanger. The air conditioner is characterized by being set longer than the time required for the operation.

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