WO2013146731A1

WO2013146731A1 - Refrigeration device

Info

Publication number: WO2013146731A1
Application number: PCT/JP2013/058687
Authority: WO
Inventors: 奥田　則之; 瀬戸口　隆之; 谷本　啓介
Original assignee: ダイキン工業株式会社
Priority date: 2012-03-28
Filing date: 2013-03-26
Publication date: 2013-10-03
Also published as: KR101617574B1; AU2013241498B2; EP2848876A1; CN104185765A; JP2013204922A; KR20140148438A; JP5617860B2; AU2013241498A1; US20150075202A1; CN104185765B; EP2848876A4

Abstract

An air conditioning device (1) is configured so that, in cooling operation, a refrigerant flows sequentially through a compressor (21), an outdoor heat exchanger (23), an expansion mechanism (24), and an indoor heat exchanger (41) and so that, in heating operation, the refrigerant flows sequentially through the compressor (21), the indoor heat exchanger (41), the expansion mechanism (24), and the outdoor heat exchanger (23). The air conditioning device (1) uses R32 as the refrigerant. The volume of the outdoor heat exchanger (23) is less than or equal to the volume of the indoor heat exchanger (41). A refrigerant storage tank (25) for storing the refrigerant is provided between the outdoor heat exchanger (23) and the expansion mechanism (24).

Description

Refrigeration equipment

The present invention relates to a refrigeration apparatus, and more particularly to a refrigeration apparatus that uses R32 as a refrigerant and can perform a cooling operation and a heating operation.

As a conventional refrigeration apparatus such as an air conditioner capable of cooling and heating operation, there is one using R32 as a refrigerant as described in Patent Document 1 (Japanese Patent Laid-Open No. 2001-194015). In this refrigeration apparatus, during the cooling operation (cooling operation), the refrigerant flows in the order of the gas-liquid separator (refrigerant storage tank), the compressor, the outdoor heat exchanger, the expansion valve (expansion mechanism), and the indoor heat exchanger. ing. Further, during the heating operation (heating operation), the refrigerant flows in the order of the refrigerant storage tank, the compressor, the indoor heat exchanger, the expansion mechanism, and the outdoor heat exchanger. In this refrigeration apparatus, the optimum refrigerant amount during the cooling operation is different from the optimum refrigerant amount during the heating operation. For this reason, the volume of the outdoor heat exchanger that functions as a radiator during the cooling operation is different from the volume of the indoor heat exchanger that functions as a radiator during the heating operation. Usually, since the volume of the outdoor heat exchanger is larger than the volume of the indoor heat exchanger, the refrigerant that cannot be accommodated by the indoor heat exchanger during the heating operation is stored in a refrigerant storage tank connected to the suction side of the compressor. Stored temporarily.

However, since the above-described refrigeration apparatus uses R32 as the refrigerant, the solubility of the refrigeration oil enclosed with the refrigerant for lubricating the compressor tends to be extremely low under low temperature conditions. For this reason, when the pressure in the refrigeration cycle is low, the solubility of the refrigeration oil is greatly reduced due to a decrease in the refrigerant temperature, and the refrigerant R32 and the refrigeration oil are separated into two layers in the refrigerant storage tank that is low in the refrigeration cycle However, it is difficult for refrigeration oil to return to the compressor.
In the above refrigeration apparatus, when a high-performance radiator as described in Patent Document 2 (Japanese Patent Laid-Open No. 6-143991) is used as an outdoor heat exchanger, the outdoor heat exchanger The volume becomes less than the volume of the indoor heat exchanger. For this reason, in this case, refrigerant (excess refrigerant) that cannot be accommodated by the outdoor heat exchanger during cooling operation is generated, and the amount exceeds the amount that can be stored in the refrigerant storage tank or the like.

As described above, in the refrigeration apparatus using R32 as the refrigerant and capable of performing the cooling operation and the heating operation, the compressor storage tank is connected to the suction side of the compressor. When the volume of the outdoor heat exchanger is less than or equal to the volume of the indoor heat exchanger, a problem of excess refrigerant also occurs.
An object of the present invention is to provide a refrigeration apparatus using R32 as a refrigerant and capable of performing a cooling operation and a heating operation, when the volume of the outdoor heat exchanger is equal to or less than the volume of the indoor heat exchanger. It is to be able to accommodate surplus refrigerant that is generated and to return the refrigeration oil to the compressor.

In the refrigeration apparatus according to the first aspect, the refrigerant flows in the order of the compressor, the outdoor heat exchanger, the expansion mechanism, and the indoor heat exchanger during the cooling operation, and the compressor, the indoor heat exchanger, the expansion mechanism, and the outdoor heat during the heating operation. It is a refrigeration apparatus in which the refrigerant flows in the order of the exchanger. In this refrigeration apparatus, R32 is used as the refrigerant, the volume of the outdoor heat exchanger is equal to or less than the volume of the indoor heat exchanger, and the refrigerant is stored between the outdoor heat exchanger and the expansion mechanism. A refrigerant storage tank is provided. The refrigeration apparatus according to the second aspect is the refrigeration apparatus according to the first aspect, wherein the refrigerant storage tank has a high pressure in the refrigeration cycle during the cooling operation and a low pressure in the refrigeration cycle during the heating operation. ing.

Since this refrigeration apparatus uses R32 as a refrigerant, there is a concern about the problem of oil return to the compressor. However, since a refrigerant storage tank is provided between the outdoor heat exchanger and the expansion mechanism, compression is performed. Compared with the case where a refrigerant storage tank is provided on the suction side of the machine, the refrigerating machine oil is easily returned to the compressor. In addition, in this refrigeration apparatus, when the capacity of the outdoor heat exchanger is equal to or less than the capacity of the indoor heat exchanger, surplus refrigerant is generated during the cooling operation, and this surplus refrigerant is accommodated in the refrigerant storage tank. Can be prevented.
Thereby, in this refrigeration apparatus, R32 is used as the refrigerant, and it is possible to accommodate surplus refrigerant generated during the cooling operation even though the volume of the outdoor heat exchanger is equal to or less than the volume of the indoor heat exchanger. At the same time, the refrigeration oil can be returned to the compressor.

The refrigeration apparatus according to the third aspect is a heat exchanger in which, in the refrigeration apparatus according to the first or second aspect, the outdoor heat exchanger uses a flat tube as a heat transfer tube. Further, the refrigeration apparatus according to the fourth aspect is the refrigeration apparatus according to the third aspect, wherein the outdoor heat exchangers are arranged in a plurality of flat tubes arranged so as to be stacked at intervals, and adjacent flat tubes. And a heat exchanger having sandwiched fins. Further, the refrigeration apparatus according to the fifth aspect is the refrigeration apparatus according to the third aspect, wherein the outdoor heat exchanger has a plurality of flat tubes arranged so as to be stacked at intervals, and a cut into which the flat tubes are inserted. And a fin formed with a notch.

In this refrigeration apparatus, since the capacity of the outdoor heat exchanger becomes less than or equal to the capacity of the indoor heat exchanger by using a flat tube as the heat transfer tube, the amount of refrigerant in the refrigeration apparatus is reduced. In this refrigeration apparatus, surplus refrigerant is generated during the cooling operation. However, since this surplus refrigerant can be stored in the refrigerant storage tank, it is possible to prevent the refrigerant control from being hindered.

A refrigeration apparatus according to a sixth aspect is the refrigeration apparatus according to the first or second aspect, wherein the outdoor heat exchanger and the indoor heat exchanger are cross-fin heat exchangers, and the heat transfer of the outdoor heat exchanger The tube diameter is set to be thinner than the heat transfer tube diameter of the indoor heat exchanger.
In this refrigeration apparatus, since the capacity of the outdoor heat exchanger is equal to or less than the capacity of the indoor heat exchanger, similarly to the refrigeration apparatus according to the first or second aspect, the amount of refrigerant in the refrigeration apparatus is reduced. . In this refrigeration apparatus, surplus refrigerant is generated during the cooling operation. However, since this surplus refrigerant can be stored in the refrigerant storage tank, it is possible to prevent the refrigerant control from being hindered.

A refrigeration apparatus according to a seventh aspect is the refrigeration apparatus according to any one of the first to sixth aspects, wherein the bypass pipe for guiding the gas component of the refrigerant accumulated in the refrigerant storage tank to the compressor or the suction pipe of the compressor is provided. Furthermore, it is provided.
In this refrigeration apparatus, during the heating operation, that is, when the outdoor heat exchanger functions as an evaporator, the refrigerant is separated into liquid and gas in the refrigerant storage tank before the entrance of the outdoor heat exchanger, and the gas component is bypassed. Will head to. As a result, gas components that do not contribute to evaporation do not flow into the outdoor heat exchanger, and accordingly, the flow rate of the refrigerant flowing through the outdoor heat exchanger decreases, and the pressure loss of the refrigerant in the outdoor heat exchanger (that is, reduced pressure) Loss) is suppressed.

A refrigeration apparatus according to an eighth aspect is the refrigeration apparatus according to the seventh aspect, wherein the bypass pipe has a flow rate adjusting mechanism.
When the operating frequency of the compressor is high, there is a possibility that the gas-liquid two-phase refrigerant returns from the refrigerant storage tank to the compressor or the suction pipe of the compressor through the bypass pipe and is sucked into the compressor.
However, in this refrigeration apparatus, since the flow rate adjusting mechanism is provided in the bypass pipe, the liquid component of the gas-liquid two-phase refrigerant is decompressed and evaporated.
Thereby, in this refrigeration apparatus, it is possible to prevent the liquid component from returning to the compressor or the suction pipe of the compressor.
Further, in this refrigeration apparatus, during the heating operation, the refrigerant that has passed through the flow rate adjusting mechanism evaporates in the outdoor heat exchanger and then merges with the refrigerant toward the compressor or the suction pipe of the compressor. At this time, when the flow rate adjusting mechanism is an electric expansion valve, the state of the refrigerant immediately before being sucked into the compressor can be adjusted more optimally by controlling the valve opening degree. Moreover, since the flow rate of the refrigerant returning to the compressor can be increased or decreased by controlling the valve opening degree of the flow rate adjusting mechanism, the circulation flow rate of the refrigerant, that is, the indoor heat, according to the refrigeration load on the indoor heat exchanger side. The flow rate of the refrigerant flowing through the exchanger can be controlled.

A refrigeration apparatus according to a ninth aspect is the refrigeration apparatus according to any one of the first to eighth aspects, wherein the refrigerant storage tank is a gas-liquid separator.
In this refrigeration apparatus, the refrigerant storage tank composed of the gas-liquid separator has both a function of storing the liquid component and a function of separating the liquid component and the gas component.
Thereby, in this refrigeration apparatus, it is not necessary to provide a device having a refrigerant storage function and a device having a gas-liquid separation function, which contributes to simplification of the device configuration.

It is a schematic block diagram of the air conditioning apparatus as a refrigeration apparatus concerning one Embodiment of this invention. It is a schematic front view of an indoor heat exchanger. It is an external appearance perspective view of an outdoor heat exchanger. It is the graph which represented the outdoor heat exchanger volume / indoor heat exchanger volume ratio according to capability. It is a schematic block diagram of the air conditioning apparatus as a freezing apparatus concerning the modification 1. 10 is a schematic cross-sectional view of a refrigerant storage tank in Modification 2. FIG. It is an external appearance perspective view of the outdoor heat exchanger in the modification 3. It is a longitudinal cross-sectional view of the outdoor heat exchanger in the modification 3.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a refrigeration apparatus according to the present invention and modifications thereof will be described with reference to the drawings. In addition, the specific structure of the freezing apparatus concerning this invention is not restricted to the following embodiment and its modification, It can change in the range which does not deviate from the summary of invention.
(1) Configuration of Air Conditioner FIG. 1 is a schematic configuration diagram of an air conditioner 1 as a refrigeration apparatus according to an embodiment of the present invention.
The air conditioner 1 is a refrigeration apparatus capable of performing a cooling operation as a cooling operation and a heating operation as a heating operation by performing a vapor compression refrigeration cycle. The air conditioner 1 is mainly configured by connecting an outdoor unit 2 and an indoor unit 4. Here, the outdoor unit 2 and the indoor unit 4 are connected via a liquid refrigerant communication tube 5 and a gas refrigerant communication tube 6. That is, the vapor compression refrigerant circuit 10 of the air conditioner 1 is configured by connecting the outdoor unit 2 and the indoor unit 4 via the refrigerant communication pipes 5 and 6. The refrigerant circuit 10 is filled with R32 which is a kind of HFC refrigerant. The refrigerant circuit 10 is filled with refrigeration oil for lubricating the compressor 21 (described later) together with the refrigerant. Here, as the refrigerating machine oil, an ether-based synthetic oil that has some compatibility with R32, a mineral oil that is incompatible with R32, an alkylbenzene-based synthetic oil, or the like is used.

<Indoor unit>
The indoor unit 4 is installed indoors and constitutes a part of the refrigerant circuit 10. The indoor unit 4 mainly has an indoor heat exchanger 41.
The indoor heat exchanger 41 is a heat exchanger that functions as a refrigerant evaporator during cooling operation to cool indoor air, and functions as a refrigerant radiator during heating operation to heat indoor air. The liquid side of the indoor heat exchanger 41 is connected to the liquid refrigerant communication tube 5, and the gas side of the indoor heat exchanger 41 is connected to the gas refrigerant communication tube 6.
As shown in FIG. 2, the indoor heat exchanger 41 is a cross fin heat exchanger, and mainly includes heat transfer fins 411 and heat transfer tubes 412. Here, FIG. 2 is a front view of the indoor heat exchanger 41. The heat transfer fins 411 are thin aluminum flat plates, and the heat transfer fins 411 have a plurality of through holes. The heat transfer tube 412 includes a straight tube 412a inserted into the through hole of the heat transfer fin 411, and

U-shaped tubes

412b and 412c that connect ends of adjacent straight tubes 412a. The straight pipe 412 a is brought into close contact with the heat transfer fin 411 by being expanded after being inserted into the through hole of the heat transfer fin 411. The straight pipe 412a and the first U-shaped pipe 412b are integrally formed. The second U-shaped pipe 412c is welded or brazed after the straight pipe 412a is inserted into the through-hole of the heat transfer fin 411 and expanded. Is connected to the end of the straight pipe 411a.

The indoor unit 4 also has an indoor fan 42 for supplying indoor air as supply air after sucking indoor air into the indoor unit 4 and exchanging heat with the refrigerant in the indoor heat exchanger 41. . Here, as the indoor fan 42, a centrifugal fan or a multi-blade fan driven by an indoor fan motor 43 is used.
The indoor unit 4 also has an indoor side control unit 44 that controls the operation of each part constituting the indoor unit 4. The indoor side control unit 44 includes a microcomputer and a memory for controlling the indoor unit 4, and exchanges control signals and the like with a remote controller (not shown). Control signals and the like can be exchanged with the unit 2 via the transmission line 8a.
<Outdoor unit>
The outdoor unit 2 is installed outside and constitutes a part of the refrigerant circuit 10. The outdoor unit 2 mainly includes a compressor 21, a switching mechanism 22, an outdoor heat exchanger 23, an expansion mechanism 24, a refrigerant storage tank 25, a liquid side closing valve 27, and a gas side closing valve 28. is doing.

The compressor 21 is a device that compresses the low-pressure refrigerant in the refrigeration cycle until the pressure becomes high. The compressor 21 has a hermetic structure in which a rotary type or scroll type positive displacement compression element (not shown) is rotationally driven by a compressor motor 21a controlled by an inverter. The compressor 21 has a suction pipe 31 connected to the suction side and a discharge pipe 32 connected to the discharge side. The suction pipe 31 is a refrigerant pipe that connects the suction side of the compressor 21 and the first port 22 a of the switching mechanism 22. The suction pipe 31 is provided with an accumulator 29. The discharge pipe 32 is a refrigerant pipe that connects the discharge side of the compressor 21 and the second port 22 b of the switching mechanism 22.
The switching mechanism 22 is a mechanism for switching the direction of refrigerant flow in the refrigerant circuit 10. During the cooling operation, the switching mechanism 22 causes the outdoor heat exchanger 23 to function as a radiator for the refrigerant compressed in the compressor 21, and the refrigerant evaporator that has radiated the indoor heat exchanger 41 in the outdoor heat exchanger 23. Switch to function as. That is, during the cooling operation, the switching mechanism 22 switches between the second port 22b and the third port 22c and the first port 22a and the fourth port 22d. Thereby, the discharge side (here, the discharge pipe 32) of the compressor 21 and the gas side (here, the first gas refrigerant pipe 33) of the outdoor heat exchanger 23 are connected (of the switching mechanism 22 of FIG. 1). (See solid line). Moreover, the suction side (here, the suction pipe 31) of the compressor 21 and the gas refrigerant communication pipe 6 side (here, the second gas refrigerant pipe 34) are connected (see the solid line of the switching mechanism 22 in FIG. 1). ). Further, the switching mechanism 22 causes the outdoor heat exchanger 23 to function as an evaporator of the refrigerant that has dissipated heat in the indoor heat exchanger 41 during the heating operation, and the indoor heat exchanger 41 is used for the refrigerant compressed in the compressor 21. Switch to function as a radiator. That is, during the heating operation, the switching mechanism 22 switches the second port 22b and the fourth port 22d to communicate and the first port 22a and the third port 22c to communicate. As a result, the discharge side (here, the discharge pipe 32) of the compressor 21 and the gas refrigerant communication pipe 6 side (here, the second gas refrigerant pipe 34) are connected (the broken line of the switching mechanism 22 in FIG. 1). reference). Moreover, the suction side (here, the suction pipe 31) of the compressor 21 and the gas side (here, the first gas refrigerant pipe 33) of the outdoor heat exchanger 23 are connected (broken line of the switching mechanism 22 in FIG. 1). See). The first gas refrigerant pipe 33 is a refrigerant pipe that connects the third port 22 c of the switching mechanism 22 and the gas side of the outdoor heat exchanger 23. The second gas refrigerant pipe 33 is a refrigerant pipe that connects the fourth port 22d of the switching mechanism 22 and the gas refrigerant communication pipe 6 side. Here, the switching mechanism 22 is a four-way switching valve.

The outdoor heat exchanger 23 is a heat exchanger that functions as a refrigerant radiator that uses outdoor air as a cooling source during cooling operation, and functions as a refrigerant evaporator that uses outdoor air as a heating source during heating operation. The outdoor heat exchanger 23 has a liquid side connected to the liquid refrigerant pipe 35 and a gas side connected to the first gas refrigerant pipe 33. The liquid refrigerant pipe 35 is a refrigerant pipe that connects the liquid side of the outdoor heat exchanger 23 and the liquid refrigerant communication pipe 7 side.
As shown in FIG. 3, the outdoor heat exchanger 23 is a heat exchanger that uses a flat tube as a heat transfer tube. More specifically, the outdoor heat exchanger 23 is a stacked heat exchanger, and mainly includes a flat tube 231, a corrugated fin 232, and

headers

233a and 233b. Here, FIG. 3 is an external perspective view of the outdoor heat exchanger 23. The flat tube 231 is formed of aluminum or an aluminum alloy, and has a flat portion 231a serving as a heat transfer surface and a plurality of internal flow paths (not shown) through which a refrigerant flows. The flat tubes 231 are arranged in a plurality of stages so as to be stacked with an interval (ventilation space) in a state where the flat portion 231a is directed upward and downward. The corrugated fins 232 are aluminum or aluminum alloy fins bent into a corrugated shape. The corrugated fins 232 are arranged in a ventilation space sandwiched between upper and lower flat tubes 231, and a valley portion and a mountain portion are in contact with a flat portion 231 a of the flat tube 231. In addition, the trough part, the peak part, and the plane part 231a are joined by brazing or the like. The

headers

233a and 233b are connected to both ends of the flat tubes 231 arranged in a plurality of stages in the vertical direction. The

headers

233 a and 233 b have a function of supporting the flat tube 231, a function of guiding the refrigerant to the internal flow path of the flat tube 231, and a function of collecting the refrigerant that has come out of the internal flow path. When the outdoor heat exchanger 23 functions as a refrigerant radiator, the refrigerant flowing from the first inlet / outlet 234 of the first header 233a is distributed almost evenly to each internal flow path of the uppermost flat tube 231; It flows toward the second header 233b. The refrigerant that has reached the second header 233b is evenly distributed to each internal flow path of the second-stage flat tube 231 and flows toward the first header 233a. Thereafter, the refrigerant in the odd-numbered flat tubes 231 flows toward the second header 233b, and the refrigerant in the even-numbered flat tubes 231 flows toward the first header 233a. Then, the refrigerant in the flat tube 231 at the lowest level and the even number level flows toward the first header 233a, collects at the first header 233a, and flows out from the second inlet / outlet 235 of the first header 233a. When the outdoor heat exchanger 23 functions as a refrigerant evaporator, the refrigerant flows in from the second inlet / outlet 235 of the first header 233a, and the

flat tubes

231 and 231 in the opposite direction to the function as a refrigerant radiator. After flowing through the

headers

233a and 233b, it flows out from the first entrance / exit 234 of the first header 233a. When the outdoor heat exchanger 23 functions as a refrigerant radiator, the refrigerant flowing in the flat tube 231 radiates heat to the airflow flowing in the ventilation space via the corrugated fins 232. Further, when the outdoor heat exchanger 23 functions as a refrigerant evaporator, the refrigerant flowing through the flat tube 231 absorbs heat from the air flow flowing through the ventilation space via the corrugated fins 232. Here, the capacity of the outdoor heat exchanger 23 is smaller than the capacity of the indoor heat exchanger 41 by using the laminated heat exchanger as described above as the outdoor heat exchanger 23. This point will be described with reference to FIG. 4 using a packaged air conditioner as an example. Here, FIG. 4 is a graph showing the outdoor heat exchanger volume / indoor heat exchanger volume ratio by capacity. In FIG. 4, ◇ is a normal type of packaged air conditioner (cross fin type outdoor heat exchanger), ◆ is an outdoor heat exchanger of package air conditioner small diameter type (stacked type outdoor heat exchanger), and △ is a normal type of room air conditioner ( Cross fin type outdoor heat exchanger), and ▲ indicate outdoor heat exchanger small diameter type (stacked type outdoor heat exchanger) of room air conditioner. According to FIG. 4, when both the outdoor heat exchanger and the indoor heat exchanger are cross fin heat exchangers, only the outdoor heat exchanger is changed to a stacked heat exchanger having equivalent heat exchanging performance. When changed, the outdoor heat exchanger capacity / indoor heat exchanger volume ratio is less than 1.0. This is because not only the volume of the laminated heat exchanger is smaller than the volume of the cross fin type outdoor heat exchanger, but also the volume of the cross fin type indoor heat exchanger 41 connected thereto. Is meant to be. For this reason, in the air conditioning apparatus 1, surplus refrigerant is generated during the cooling operation. Therefore, in the air conditioner 1, the surplus refrigerant is accommodated in the refrigerant storage tank 25. According to FIG. 4, when the outdoor heat exchanger capacity / indoor heat exchanger volume ratio is 0.3 to 0.9, it is preferable to use the refrigerant storage tank 25 that stores excess refrigerant. Even when the exchanger capacity / indoor heat exchanger volume ratio is 1.0, the use of the refrigerant storage tank 25 enables stable refrigerant control.

The expansion mechanism 24 is a device that reduces the high-pressure refrigerant in the refrigeration cycle temporarily stored in the refrigerant storage tank 25 to the low pressure in the refrigeration cycle during the cooling operation. The expansion mechanism 24 is a device that reduces the high-pressure refrigerant in the refrigeration cycle that has radiated heat in the indoor heat exchanger 41 to the low pressure in the refrigeration cycle during heating operation. The expansion mechanism 24 is provided in a portion of the liquid refrigerant pipe 35 near the liquid side closing valve 27. Here, an electric expansion valve is used as the expansion mechanism 24.
The refrigerant storage tank 25 is provided between the outdoor heat exchanger 23 and the expansion mechanism 24. The refrigerant storage tank 25 is a container that is capable of storing high-pressure refrigerant in the refrigeration cycle that has become high pressure in the refrigeration cycle during cooling operation and radiates heat in the outdoor heat exchanger 23. The refrigerant storage tank 25 is a container capable of storing a low-pressure refrigerant in the refrigeration cycle that is low in the refrigeration cycle during heating operation and decompressed in the expansion mechanism 24. For example, the amount of liquid refrigerant that can be accommodated in the indoor heat exchanger 41 during the heating operation in which the indoor heat exchanger 41 functions as a refrigerant radiator is 1100 cc, and the outdoor heat exchanger 23 functions as a refrigerant radiator. When the amount of liquid refrigerant that can be accommodated in the outdoor heat exchanger 23 during the cooling operation is 800 cc, the remaining 300 cc of liquid refrigerant that cannot be accommodated in the outdoor heat exchanger 23 during the cooling operation is stored in the refrigerant storage tank 25. Temporarily accommodated.

The liquid side shut-off valve 27 and the gas side shut-off valve 28 are valves provided at connection ports with external devices and pipes (specifically, the liquid refrigerant communication pipe 5 and the gas refrigerant communication pipe 6). The liquid side closing valve 26 is provided at the end of the liquid refrigerant pipe 35. The gas side closing valve 27 is provided at the end of the second gas refrigerant pipe 34.
The outdoor unit 2 has an outdoor fan 36 for sucking outdoor air into the outdoor unit 2, exchanging heat with the refrigerant in the outdoor heat exchanger 23, and then discharging the air to the outside. Here, a propeller fan or the like driven by an outdoor fan motor 37 is used as the outdoor fan 36.
The outdoor unit 2 also has an outdoor control unit 38 that controls the operation of each unit constituting the outdoor unit 2. And the outdoor side control part 38 has a microcomputer, memory, etc. for controlling the outdoor unit 2, and controls signal between the indoor side control parts 43 of the indoor unit 4 via the transmission line 8a. Etc. can be exchanged. That is, the control part 8 which performs operation control of the whole air conditioning apparatus 1 is comprised by the transmission line 8a which connects between the indoor side control part 44, the outdoor side control part 38, and the

control parts

38 and 44. FIG.

The controller 8 can control the operation of various devices and

valves

21a, 22, 24, 26, 37, 43, and the like based on various operation settings, detection values of various sensors, and the like.
<Refrigerant communication pipe>
Refrigerant communication pipes 5 and 6 are refrigerant pipes constructed on site when the air conditioner 1 is installed at an installation location such as a building, and installation conditions such as an installation location and a combination of an outdoor unit and an indoor unit. Those having various lengths and tube diameters are used.
As described above, the refrigerant circuit 10 of the air conditioner 1 is configured by connecting the outdoor unit 2, the indoor unit 4, and the refrigerant communication pipes 5 and 6. During the cooling operation as the cooling operation, the refrigerant circuit 10 performs a refrigeration cycle in which the refrigerant flows in the order of the compressor 21, the outdoor heat exchanger 23, the refrigerant storage tank 25, the expansion mechanism 24, and the indoor heat exchanger 41. It has become. The refrigerant circuit 10 performs a refrigeration cycle in which the refrigerant flows in the order of the compressor 21, the indoor heat exchanger 41, the expansion mechanism 24, the refrigerant storage tank 25, and the outdoor heat exchanger 23 during the heating operation as the heating operation. It is like that. The air conditioner 1 can perform various operations such as a cooling operation and a heating operation by the control unit 8 including the indoor side control unit 44 and the outdoor side control unit 38.

(2) Operation of Air Conditioner The air conditioner 1 can perform a cooling operation and a heating operation as described above. Hereinafter, the operation | movement at the time of air_conditionaing | cooling operation of the air conditioning apparatus 1 and heating operation is demonstrated.
<Heating operation>
During the heating operation, the switching mechanism 22 is switched to the state indicated by the broken line in FIG. 1, that is, the communication between the second port 22b and the fourth port 22d and the communication between the first port 22a and the third port 22c. Do.
In this refrigerant circuit 10, the low-pressure refrigerant in the refrigeration cycle is sucked into the compressor 21, compressed until it reaches a high pressure in the refrigeration cycle, and then discharged.
The high-pressure refrigerant discharged from the compressor 21 is sent to the indoor heat exchanger 41 through the switching mechanism 22, the gas side closing valve 28 and the gas refrigerant communication pipe 6.

The high-pressure refrigerant sent to the indoor heat exchanger 41 radiates heat by exchanging heat with indoor air in the indoor heat exchanger 41. Thereby, indoor air is heated. Here, since the capacity | capacitance of the indoor heat exchanger 41 is larger than the capacity | capacitance of the outdoor heat exchanger 23, most liquid refrigerants are accommodated in the indoor heat exchanger 41 at the time of heating operation.
The high-pressure refrigerant radiated by the indoor heat exchanger 41 is sent to the expansion mechanism 24 through the liquid refrigerant communication pipe 5 and the liquid side shut-off valve 27.
The refrigerant sent to the expansion mechanism 24 is depressurized to a low pressure in the refrigeration cycle by the expansion mechanism 24, and then sent to the refrigerant storage tank 25 to be accumulated in the refrigerant storage tank 25. Then, the refrigerant in the refrigerant storage tank 25 is sent to the outdoor heat exchanger 23.
The low-pressure refrigerant sent to the outdoor heat exchanger 23 evaporates by exchanging heat with outdoor air supplied by the outdoor fan 36 in the outdoor heat exchanger 23.

The low-pressure refrigerant evaporated in the outdoor heat exchanger 23 is again sucked into the compressor 21 through the switching mechanism 22.
<Cooling operation>
During the cooling operation, the switching mechanism 22 is in a state indicated by a solid line in FIG. 1, that is, switching between the second port 22b and the third port 22c and the first port 22a and the fourth port 22d. Do.
In this refrigerant circuit 10, the low-pressure refrigerant in the refrigeration cycle is sucked into the compressor 21, compressed until it reaches a high pressure in the refrigeration cycle, and then discharged.
The high-pressure refrigerant discharged from the compressor 21 is sent to the outdoor heat exchanger 23 through the switching mechanism 22.

The high-pressure refrigerant sent to the outdoor heat exchanger 23 radiates heat by exchanging heat with outdoor air in the outdoor heat exchanger 23.
The high-pressure refrigerant that has radiated heat in the outdoor heat exchanger 23 is sent to the refrigerant storage tank 25. Here, since the capacity | capacitance of the outdoor heat exchanger 23 is below the capacity | capacitance of the indoor heat exchanger 41, the outdoor heat exchanger 23 cannot accommodate all the liquid refrigerants at the time of air_conditionaing | cooling operation. For this reason, liquid refrigerant that cannot be stored in the outdoor heat exchanger 23 is accumulated in the refrigerant storage tank 25, and the refrigerant storage tank 25 is filled with high-pressure liquid refrigerant in the refrigeration cycle. The liquid refrigerant in the refrigerant storage tank 25 is depressurized to a low pressure in the refrigeration cycle by the expansion mechanism 24 and then sent to the indoor heat exchanger 41 through the liquid side closing valve 27 and the liquid refrigerant communication pipe 5.
The low-pressure refrigerant sent to the indoor heat exchanger 41 evaporates by exchanging heat with indoor air in the indoor heat exchanger 41. Thereby, indoor air is cooled.

The low-pressure refrigerant evaporated in the indoor heat exchanger 51 is again sucked into the compressor 21 through the gas refrigerant communication pipe 6, the gas side shut-off valve 28, and the switching mechanism 22.
(3) Features of the air conditioner The air conditioner 1 of the present embodiment has the following features.
In the air conditioner 1, as described above, R32 is used as the refrigerant. For this reason, there is a concern about the problem of oil return to the compressor 21. Further, in the air conditioner 1, as described above, the indoor heat exchanger 41 is a cross-fin heat exchanger, the outdoor heat exchanger 23 is a laminated heat exchanger using a flat tube 231 as a heat transfer tube, The volume of the heat exchanger 23 is 100% or less of the volume of the indoor heat exchanger 41. For this reason, surplus refrigerant is generated during the cooling operation, which may hinder refrigerant control.

In contrast, in the air conditioner 1, as described above, the refrigerant storage tank 25 is provided between the outdoor heat exchanger 23 and the expansion mechanism 24, and the refrigerant storage tank 25 is in the refrigeration cycle during the cooling operation. The pressure is high, and the pressure is low in the refrigeration cycle during heating operation.
For this reason, in the air conditioner 1, compared with the case where the refrigerant storage tank is provided on the suction side of the compressor 21, the refrigeration oil is easily returned to the compressor 21, and the problem of oil return to the compressor 21 is solved. . In addition, in the air conditioner 1, since the capacity of the outdoor heat exchanger 23 is equal to or less than the capacity of the indoor heat exchanger 41, surplus refrigerant generated during the cooling operation is accommodated in the refrigerant storage tank 25, which hinders refrigerant control. Can be prevented.
Thereby, in the air conditioning apparatus 1, R32 is used as the refrigerant, and the excess refrigerant generated during the cooling operation is accommodated even though the volume of the outdoor heat exchanger 23 is equal to or less than the volume of the indoor heat exchanger 41. And the refrigerating machine oil can be returned to the compressor 21.

(4) Modification 1
In the above embodiment (see FIG. 1), as shown in FIG. 5, a bypass pipe 30 is further provided for guiding the gas component of the refrigerant stored in the refrigerant storage tank 25 to the compressor 21 or the suction pipe 31 of the compressor 21. May be.
Specifically, for example, the refrigerant immediately before entering the refrigerant storage tank 25 during the heating operation includes a gas component generated when passing through the expansion mechanism 24. For this reason, after this refrigerant enters the refrigerant storage tank 25, it is separated into a liquid component and a gas component, the liquid refrigerant is stored on the lower side, and the gas refrigerant is stored on the upper side. The gas refrigerant separated in the refrigerant storage tank 25 flows through the bypass pipe 30 to the suction pipe 31 of the compressor 21. Further, the liquid refrigerant separated in the refrigerant storage tank 25 is depressurized in the expansion mechanism 24 and then flows to the outdoor heat exchanger 23. Here, the bypass pipe 30 is provided so as to connect between the upper part of the refrigerant storage tank 25 and the middle part of the suction pipe 31. In the middle of the bypass pipe 30, a flow rate adjusting mechanism 30a is provided. Here, an electric expansion valve is used as the flow rate adjusting mechanism 30a. The outlet of the bypass pipe 30 may be directly connected to the compressor 21 instead of being connected to the middle part of the suction pipe 31. The flow rate adjusting mechanism 30a is controlled by the control unit 8 in the same manner as other devices and

valves

21a, 22, 24, 26, 37, 43 and the like. Specifically, during the heating operation, the flow rate adjustment mechanism 30a is controlled to be in an open state, and during the cooling operation, the flow rate adjustment mechanism 30a is controlled to be in a closed state.

Thus, during the heating operation, the high-pressure refrigerant that has been radiated in the indoor heat exchanger 41 and then sent to the expansion mechanism 24 is depressurized by the expansion mechanism 24 to a low pressure in the refrigeration cycle, and then sent to the refrigerant storage tank 25. The refrigerant immediately before entering the refrigerant storage tank 25 includes a gas component generated when the expansion mechanism 24 is depressurized. After entering the refrigerant storage tank 25, the refrigerant is separated into a liquid component and a gas component. The liquid refrigerant in the refrigeration cycle is stored on the lower side, and the low-pressure gas refrigerant in the refrigeration cycle is stored on the upper side. At this time, as described above, the flow rate adjusting mechanism 30a of the bypass pipe 30 is controlled to be in the open state, so that the gas refrigerant in the refrigerant storage tank 25 goes to the suction pipe 31 of the compressor 21 through the bypass pipe 30. The liquid refrigerant in the refrigerant storage tank 25 is sent to the outdoor heat exchanger 23. The low-pressure refrigerant sent to the outdoor heat exchanger 23 evaporates in the outdoor heat exchanger 23 by exchanging heat with outdoor air supplied by the outdoor fan 36. At this time, the refrigerant flowing into the outdoor heat exchanger 23 is reduced by the gas-liquid separation operation in the refrigerant storage tank 25 and the operation of sucking the gas refrigerant separated into the compressor 21 through the bypass pipe 30. . For this reason, since the flow volume of the refrigerant | coolant which flows through the outdoor heat exchanger 23 reduces and a pressure loss can be made small by that much, the decompression loss in a refrigerating cycle can be reduced.

On the other hand, during the cooling operation, the flow rate adjusting mechanism 30a of the bypass pipe 30 is controlled to be closed as described above, so that the liquid refrigerant accumulated in the refrigerant storage tank 25 does not flow to the bypass pipe 30. The liquid refrigerant in the refrigerant storage tank 25 is depressurized to a low pressure in the refrigeration cycle by the expansion mechanism 24 and then sent to the indoor heat exchanger 41 through the liquid side closing valve 27 and the liquid refrigerant communication pipe 5.
And in the air conditioning apparatus 1 of this modification, the bypass pipe 30 which guides the gas component of the refrigerant | coolant which accumulates in the refrigerant | coolant storage tank 25 to the compressor 21 or the suction pipe 31 of the compressor 21 as mentioned above is provided. Therefore, in addition to the functions and effects of the above embodiment, the following functions and effects can be obtained.
<A>
In the air conditioner 1, the refrigerant decompressed in the expansion mechanism 24 during the heating operation is separated into the liquid component and the gas component in the refrigerant storage tank 25, and the gas component goes to the bypass pipe 30.

As a result, in the air conditioner 1, during heating operation, gas components that do not contribute to evaporation do not flow into the outdoor heat exchanger 23 that functions as a refrigerant evaporator. The flow rate of the refrigerant flowing through the heat exchanger 23 can be reduced, and the decompression loss in the refrigeration cycle can be reduced.
<B>
When the operating frequency of the compressor 21 is high, the refrigerant in the gas-liquid two-phase state returns from the refrigerant storage tank 25 to the compressor 21 or the suction pipe 31 of the compressor 21 through the bypass pipe 30 and is sucked into the compressor 21. There is a fear.
However, in the air conditioner 1, since the flow adjustment mechanism 30a is provided in the bypass pipe 30, the liquid component of the refrigerant in the gas-liquid two-phase state is decompressed and evaporated.

Thereby, in the air conditioning apparatus 1, it is possible to prevent the liquid component from returning to the compressor 21 or the suction pipe 31 of the compressor 21.
<C>
In the air conditioner 1, during the heating operation, the refrigerant that has passed through the flow rate adjustment mechanism 30 a evaporates in the indoor heat exchanger 41 and the outdoor heat exchanger 23, and then enters the compressor 21 or the suction pipe 31 of the compressor 21. It will be merged with the refrigerant. At this time, when the flow rate adjustment mechanism 30a is an electric expansion valve, the refrigerant state immediately before being sucked into the compressor 21 can be adjusted more optimally by controlling the valve opening degree. Moreover, since the flow rate of the refrigerant returning to the compressor 21 can be increased or decreased by controlling the valve opening degree of the flow rate adjusting mechanism 30a, the circulation flow rate of the refrigerant according to the refrigeration load on the indoor heat exchanger 41 side, that is, The flow rate of the refrigerant flowing through the indoor heat exchanger 41 can be controlled.

(5) Modification 2
In the first modification, a container for storing the refrigerant is employed as the refrigerant storage tank 25, but the present invention is not limited to this. For example, a cyclone type gas-liquid separator as shown in FIG. 6 may be employed. .
The refrigerant storage tank 25 of this modification mainly includes a cylindrical container 251, a first connection pipe 252, a second connection pipe 253, and a third connection pipe 254.
The first connection pipe 252 is connected in the tangential direction of the circumferential side wall of the cylindrical container 251, and communicates the inside of the cylindrical container 251 and the expansion mechanism 24. The second connection pipe 253 is connected to the bottom wall of the cylindrical container 251 and communicates the inside of the cylindrical container 251 and the outdoor heat exchanger 23. The third connection pipe 254 is connected to the upper wall of the cylindrical container 251 and connects the inside of the cylindrical container 251 and the bypass pipe 30.

With such a configuration, during heating operation, the low-pressure refrigerant in the refrigeration cycle flowing into the cylindrical container 251 through the first connection pipe 252 swirls along the inner peripheral surface 251a of the circumferential side wall of the cylindrical container 251. At that time, the liquid refrigerant adheres to the inner peripheral surface 251a, and the liquid refrigerant and the gas refrigerant are efficiently separated.
The liquid refrigerant descends due to gravity, accumulates on the lower side, and flows out from the cylindrical container 251 through the second connection pipe 253. On the other hand, the gas refrigerant rises while turning, accumulates on the upper side, and flows out of the cylindrical container 251 through the third connection pipe 254.
As described above, in this modification, since the cyclone type gas-liquid separator is employed as the refrigerant storage tank 25, gas-liquid separation can be performed efficiently. In addition, the refrigerant storage tank 25 composed of a gas-liquid separator has both a refrigerant storage function for storing liquid refrigerant and a function for separating the liquid component and the gas component. This eliminates the need for a device and contributes to the simplification of the device configuration.

(6) Modification 3
In the embodiment and the first and second modifications, a stacked heat exchanger having a plurality of flat tubes 231 and corrugated fins 232 is illustrated as an example of the outdoor heat exchanger 23 that uses a flat tube 231 as a heat transfer tube. Yes. The outdoor heat exchanger 23 is arranged such that a plurality of flat tubes 231 are stacked at intervals, and corrugated fins 232 are sandwiched between adjacent flat tubes 231.
However, the outdoor heat exchanger 23 is not limited to the configuration in the above embodiment and the first and second modifications, and is arranged to be stacked with an interval as shown in FIGS. 7 and 8, for example. A laminated heat exchanger having a plurality of flat tubes 231 and fins 236 formed with notches 236a into which the flat tubes 231 are inserted may be used.
Even in this case, the same effects as those of the above embodiment and the first and second modifications can be obtained.

(7) Modification 4
In the said embodiment and the

modification

1, 2, the laminated heat exchanger which has the some flat tube 231 and the corrugated fin 232 is illustrated as an example of the outdoor heat exchanger 23 which uses the flat tube 231 as a heat exchanger tube. Yes. The outdoor heat exchanger 23 is arranged such that a plurality of flat tubes 231 are stacked at intervals, and corrugated fins 232 are sandwiched between adjacent flat tubes 231.
However, the outdoor heat exchanger 23 is not limited to the configuration in the above embodiment and the first and second modifications. For example, the flat tube is formed in a meandering shape, and the fin is between the adjacent surfaces of the flat tube. It may be configured to be sandwiched between.
Even in this case, the same effects as those of the above embodiment and the first and second modifications can be obtained.

(8) Modification 5
In the above embodiment and Modifications 1 to 4, the outdoor heat exchanger 23 is a stacked heat exchanger having a plurality of flat tubes 231 and fins 236 formed with corrugated fins 232 and notches 236a. It is not limited to this. For example, in the case of a refrigeration apparatus that cools the outdoor heat exchanger 23 with water during the cooling operation, both the outdoor heat exchanger 23 and the indoor heat exchanger 41 are cross-fin heat exchangers, and the outdoor heat exchanger 23 The heat transfer tube diameter may be narrower than the heat transfer tube diameter of the indoor heat exchanger 41.
Even in this case, the same effects as those of the above-described embodiment and Modifications 1 to 4 can be obtained.

The present invention is widely applicable to a refrigeration apparatus that uses R32 as a refrigerant and can perform a cooling operation and a heating operation.

1 Air conditioning equipment (refrigeration equipment)
DESCRIPTION OF SYMBOLS 21 Compressor 23 Outdoor heat exchanger 24 Expansion mechanism 25 Refrigerant storage tank 30 Bypass pipe 30a Flow rate adjustment mechanism 41 Indoor heat exchanger

JP 2001-194015 A JP-A-6-143991

Claims

During the cooling operation, the refrigerant flows in the order of the compressor (21), the outdoor heat exchanger (23), the expansion mechanism (24), and the indoor heat exchanger (41). During the heating operation, the compressor, the indoor heat exchanger, In the refrigeration apparatus in which the refrigerant flows in the order of the expansion mechanism and the outdoor heat exchanger,
R32 is used as a refrigerant,
The volume of the outdoor heat exchanger is less than or equal to the volume of the indoor heat exchanger;
Between the outdoor heat exchanger and the expansion mechanism, a refrigerant storage tank (25) for storing a refrigerant is provided.
Refrigeration equipment (1).
The refrigerant storage tank (25) is provided so as to have a high pressure in the refrigeration cycle during the cooling operation and a low pressure in the refrigeration cycle during the heating operation.
The refrigeration apparatus (1) according to claim 1.
The outdoor heat exchanger (23) is a heat exchanger using a flat tube as a heat transfer tube,
The refrigeration apparatus (1) according to claim 1 or 2.
The outdoor heat exchanger (23) is a heat exchanger having a plurality of the flat tubes arranged to be stacked at intervals and fins sandwiched between the adjacent flat tubes.
The refrigeration apparatus (1) according to claim 3.
The outdoor heat exchanger (23) is a heat exchanger having a plurality of the flat tubes arranged so as to be stacked at intervals and fins in which notches into which the flat tubes are inserted are formed.
The refrigeration apparatus (1) according to claim 3.
The outdoor heat exchanger (23) and the indoor heat exchanger (41) are cross fin heat exchangers,
The heat transfer tube diameter of the outdoor heat exchanger is set to be thinner than the heat transfer tube diameter of the indoor heat exchanger,
The refrigeration apparatus (1) according to claim 1 or 2.
A bypass pipe (30) that guides the gas component of the refrigerant stored in the refrigerant storage tank (25) to the compressor (21) or a refrigerant pipe on the suction side of the compressor;
The refrigeration apparatus (1) according to any one of claims 1 to 6.
The bypass pipe (30) has a flow rate adjusting mechanism (30a).
The refrigeration apparatus (1) according to claim 7.
The refrigerant storage tank (25) is a gas-liquid separator.
The refrigeration apparatus (1) according to any one of claims 1 to 8.