WO2021140622A1

WO2021140622A1 - Air conditioning apparatus

Info

Publication number: WO2021140622A1
Application number: PCT/JP2020/000494
Authority: WO
Inventors: 佐藤　正典; 和平新宮
Original assignee: 三菱電機株式会社
Priority date: 2020-01-09
Filing date: 2020-01-09
Publication date: 2021-07-15
Also published as: JPWO2021140622A1; EP4089344A1; US20220397318A1; JP7350892B2; EP4089344A4

Abstract

A flow path switch (240) is provided with a first opening (P1) to a fourth opening (P4). An internal heat exchanger (260) is provided with a first internal flow path (261a) and a second internal flow path (261b). The discharge side of a compressor (230) is connected to the first opening (P1). One end of a first heat exchange unit (210) is connected to the fourth opening (P4). One end of the second internal flow path (261b) is connected to a second opening (P2). A first branch (BP1) is connected to one end of a second valve (280) and a third opening (P3). The other end of the second valve (280) is connected to a second branch (BP2). The second branch (BP2) is connected to the suction side of the compressor (230) and the other end of the second internal flow path (261b). When the operation mode of an air conditioning apparatus (1000) is a first mode, the second valve (280) opens and the first opening (P1) is connected to the fourth opening (P4), and the second opening (P2) is connected to the third opening (P3). When the operation mode of the air conditioning apparatus (1000) is the second mode, the second valve (280) is closed, the first opening (P1) is connected to the third opening (P3), and the second opening (P2) is connected to the fourth opening (P4).

Description

Air conditioner

This disclosure relates to an air conditioner.

European refrigerant regulations require that _{carbon dioxide (CO 2} ), which is a natural refrigerant, be used as the refrigerant used in the refrigeration cycle of air conditioners. When a CO ₂ refrigerant is used, the theoretical efficiency is low and the performance is lowered as compared with a refrigerant such as R407c, which is a general refrigerant. In order to suppress the deterioration of performance, a technique is known in which an internal heat exchanger is used to widen the enthalpy difference of the evaporator and improve the performance.

For example, the refrigeration cycle apparatus of JP-A-2003-194432 (Patent Document 1) operates as follows. In the cooling operation mode, the high-temperature and high-pressure refrigerant discharged from the compressor is cooled by the heat source side heat exchanger and further cooled by the internal heat exchanger. On the other hand, in the heating operation mode, the high-temperature and high-pressure refrigerant discharged from the compressor is cooled by the user-side heat exchanger, further decompressed by the decompressor, and then flows into the internal heat exchanger. In the heating operation mode, the internal heat exchanger is rarely used because the difference between the temperature of the refrigerant flowing through the low-pressure side flow path and the temperature of the refrigerant flowing through the high-pressure side flow path is small. With such a configuration, the refrigerant can be circulated in both the cooling operation mode and the heating operation mode without newly providing a four-way valve.

Japanese Unexamined Patent Publication No. 2003-194432

However, the apparatus described in Patent Document 1 has the following problems.
In the cooling operation mode, since _{the external fluid that heat exchangers with the CO 2} refrigerant in the outdoor heat exchanger is the outside air (about 30 to 40 ° C.) in summer, the temperature of the refrigerant discharged from the compressor becomes very high. When the internal heat exchanger is used in the cooling operation mode, the discharge temperature of the compressor becomes higher, which may exceed the limit value at which the compressor can operate normally. In such a case, the compressor motor is damaged and the refrigerating machine oil is deteriorated. Therefore, protection control such as lowering the frequency of the compressor is executed. As a result, the operating performance of the air conditioner deteriorates.

Further, in the cooling operation mode, the CO ₂ refrigerant becomes supercritical in the outdoor heat exchanger. As a result, the operating performance of the air conditioner is lower than when _{the CO 2 refrigerant is used in the two-phase region.} In order to cover this, it is necessary to make the heat transfer area of the outdoor heat exchanger larger than the heat transfer area of the indoor heat exchanger, which causes the following problems. Using the internal heat exchanger in the cooling operation mode increases the amount of refrigerant required, which increases the cost and the risk of leakage of _{CO 2 refrigerant.} In the heating operation mode, since the internal heat exchanger is not used, the amount of the refrigerant in the indoor heat exchanger is large, so that the high pressure in the air conditioner rises and the performance of the air conditioner deteriorates.

Therefore, an object of the present disclosure is to provide an air conditioner that _{has two operating modes and can achieve high performance even when a CO 2 refrigerant is used.}

The air conditioner of the present disclosure includes a compressor, a flow path switch, a first heat exchange unit, a second heat exchange unit, an internal heat exchanger, a first valve, and a second valve, and includes a refrigerant circuit through which a refrigerant flows. Be prepared. The flow path switch includes a first opening, a second opening, a third opening, and a fourth opening. The internal heat exchanger includes a first internal flow path and a second internal flow path. The discharge side of the compressor and the first opening of the flow path switch are connected. One end of the first heat exchange section and the fourth opening of the flow path switch are connected. The other end of the first heat exchange portion and one end of the first valve are connected. The other end of the first valve and one end of the first internal flow path of the internal heat exchanger are connected. The other end of the first internal flow path of the internal heat exchanger and one end of the second heat exchange portion are connected. One end of the second internal flow path of the internal heat exchanger and the second opening of the flow path switch are connected. The other end of the second heat exchange portion and the first branch portion are connected. The first branch portion, one end of the second valve, and the third opening of the flow path switch are connected. The other end of the second valve and the second branch portion are connected. The second branch is connected to the suction side of the compressor and the other end of the second internal flow path of the internal heat exchanger. When the operation mode of the air conditioner is the first mode, the second valve is opened, the first opening and the fourth opening are connected, and the second opening and the third opening are connected. When the operation mode of the air conditioner is the second mode, the second valve is closed, the first opening and the third opening are connected, and the second opening and the fourth opening are connected.

In the air conditioner of the present disclosure, when the operation mode of the air conditioner is the first mode, the second valve is opened, the first opening and the fourth opening are connected, and the second opening and the third opening are connected. And connect. When the operation mode of the air conditioner is the second mode, the second valve is closed, the first opening and the third opening are connected, and the second opening and the fourth opening are connected.

Therefore, according to the air conditioner of the present disclosure, it is possible to provide two operation modes and realize high performance even when _{a CO 2 refrigerant is used.}

It is a figure which shows the structure of the air conditioner 1000 of Embodiment 1. FIG. It is a figure which shows the structure of the air conditioner 1100 of a reference example. It is a side view of the outdoor unit 200. It is a side view of the outdoor unit 200. It is a figure which shows the structure of the air conditioner 1001 of Embodiment 2. It is a figure which shows the structure of the air conditioner 1002 of Embodiment 3.

Hereinafter, embodiments will be described with reference to the drawings.
Embodiment 1.
FIG. 1 is a diagram showing the configuration of the air conditioner 1000 of the first embodiment.

The air conditioner 1000 includes an outdoor unit 200 and an indoor unit 100.
The outdoor unit 200 includes a compressor 230, a first heat exchange unit 210, a flow path switch 240, a first valve 250, a second valve 280, an internal heat exchanger 260, and an outdoor blower 220. The first heat exchanger 210 includes a first outdoor heat exchanger 211 and a second outdoor heat exchanger 212.

The indoor unit 100 includes a second heat exchange unit 110 and an indoor blower 120. The second heat exchanger 110 includes a first chamber heat exchanger 111 and a second chamber heat exchanger 112.

The refrigerant circuit RC1 includes a compressor 230, a flow path switch 240, a first heat exchange unit 210, a second heat exchange unit 110, an internal heat exchanger 260, a first valve 250, and a second valve 280. The refrigerant sealed in the refrigerant circuit RC1 is a CO ₂ refrigerant.

The flow path switch 240 is composed of a four-way valve. The flow path switch 240 includes a first opening P1, a second opening P2, a third opening P3, and a fourth opening P4. A second flow path connecting the first opening P1 and the third opening P3 or the fourth opening P4, and a second connecting the second opening P2 and the fourth opening P4 or the third opening P3. A flow path is arranged.

The internal heat exchanger 260 includes a first internal flow path 261a and a second internal flow path 261b. The refrigerant flowing through the first internal flow path 261a and the refrigerant flowing through the second internal flow path 261b exchange heat. The first internal flow path 261a and the second internal flow path 261b are parallel. One end of the first internal flow path 261a and one end of the second internal flow path 261b are arranged in the vicinity, and the other end of the first internal flow path 261a and the other end of the second internal flow path 261b are arranged in the vicinity. ..

The discharge side of the compressor 230 and the first opening P1 of the flow path switch 240 are connected by a pipe 315M. One end of the first heat exchange section 210 and the fourth opening P4 of the flow path switch 240 are connected by a pipe 318M. The other end of the first heat exchange section 210 and one end of the first valve 250 are connected by a pipe 317M. The other end of the first valve 250 and one end of the first internal flow path 261a of the internal heat exchanger 260 are connected by a pipe 317M. The other end of the first internal flow path 261a of the internal heat exchanger 260 and one end of the second heat exchange portion 110 are connected by a pipe 316M. One end of the second internal flow path 261b of the internal heat exchanger 260 and the second opening P2 of the flow path switch 240 are connected by a pipe 312M. The other end of the second heat exchange portion 110 and the first branch portion BP1 are connected by a pipe 310M. The first branch portion BP1 and one end of the second valve 280 are connected by the first bypass pipe PB1. The first branch portion BP1 and the third opening portion P3 of the flow path switch 240 are connected by a pipe 311M. The other end of the second valve 280 and the second branch portion BP2 are connected by the first bypass pipe PB1. The second branch portion BP2 and the suction side of the compressor 230 are connected by a pipe 314M. The second branch portion BP2 and the other end of the second internal flow path 261b of the internal heat exchanger 260 are connected by the pipe 313M.

The main piping PM is composed of the piping 318M, the piping 317M, the piping 313M, the piping 314M, the piping 315M, the piping 316M, the piping 310M, the piping 311M, and the piping 312M.

The operation mode of the air conditioner 1000 includes a first mode, a second mode, and a third mode. The first mode is, for example, a cooling operation mode. The second mode is, for example, a heating operation mode. The third mode is, for example, a high load cooling operation mode.

When the operation mode of the air conditioner 1000 is the first mode and the outside air temperature exceeds the specified value, the operation mode of the air conditioner 1000 changes to the third mode. At this time, the frequency of the compressor 230 does not change. In the present embodiment, high load cooling operation is possible without changing the frequency of the compressor 230.

The compressor 230 compresses the sucked refrigerant and discharges it.
The flow path switcher 240 switches the flow path of the refrigerant according to the operation mode of the air conditioner 1000.

When the operation modes of the air conditioner 1000 are the first mode and the third mode, the first opening P1 and the fourth opening P4 are connected, and the second opening P2 and the third opening P3 are connected. To do. Therefore, when the operation modes of the air conditioner 1000 are the first mode and the third mode, the compressor 230 and the first heat exchange unit 210 are connected, and the internal heat exchanger 260 and the second heat exchange unit are connected. The 110 and the second valve 280 are connected.

When the operation mode of the air conditioner 1000 is the second mode, the first opening P1 and the third opening P3 are connected, and the second opening P2 and the fourth opening P4 are connected. Therefore, when the operation mode of the air conditioner 1000 is the second mode, the compressor 230 is connected to the second heat exchange unit 110 and the second valve 280, and the internal heat exchanger 260 and the first heat exchange unit are connected. Connects to 210.

The first heat exchange unit 210 operates as a condenser in the first mode and the third mode. The first heat exchange unit 210 operates as an evaporator in the second mode.

The second heat exchange unit 110 operates as an evaporator in the first mode and the third mode. The second heat exchange unit 110 operates as a condenser in the second mode.

The internal heat exchanger 260 exchanges heat between the refrigerant flowing from the flow path switch 240 to the compressor 230 and the refrigerant flowing from the first valve 250 to the second heat exchange unit 110 in the first mode and the third mode. In the second mode, the internal heat exchanger 260 includes the refrigerant flowing from the flow path switch 240 to the compressor 230, the refrigerant flowing from the second heat exchanger 110 to the first valve 250, and the refrigerant flowing from the first valve 250. To exchange heat.

The first valve 250 is an electronic expansion valve.
The second valve 280 is a solenoid valve. The second valve 280 opens in the first mode. The second valve 280 closes in the second and third modes.

The outdoor blower 220 sends outdoor air to the first outdoor heat exchanger 211 and the second outdoor heat exchanger 212. The indoor blower 120 sends indoor air to the first indoor heat exchanger 111 and the second indoor heat exchanger 112.

The flow of the refrigerant in the first mode in which the operation mode of the air conditioner is the first mode will be described. As shown by the broken line in FIG. 1, the compressor 230, the flow path switch 240, the first heat exchange section 210, the first valve 250, the internal heat exchanger 260, the second heat exchange section 110, and the first branch section BP1. Refrigerant flows in order.

After the first branch portion BP1, a part of the refrigerant flows in the order of the second valve 280, the second branch portion BP2, and the compressor 230. The rest of the refrigerant flows in the order of the flow path switch 240, the internal heat exchanger 260, the second branch BP2, and the compressor 230.

Explain the flow of the refrigerant in the second mode in which the operation mode of the air conditioner is the second mode. As shown by the solid line in FIG. 1, the compressor 230, the flow path switch 240, the second heat exchanger 110, the internal heat exchanger 260, the first valve 250, the first heat exchange section 210, the flow path switch 240, Refrigerant flows in the order of the internal heat exchanger 260, the second branch BP2, and the compressor 230.

The flow of the refrigerant in the third mode in which the operation mode of the air conditioner is set will be described. As shown by the dotted line in FIG. 1, the compressor 230, the flow path switch 240, the first heat exchange section 210, the first valve 250, the internal heat exchanger 260, the second heat exchange section 110, the first branch section BP1, All the refrigerant flows in the order of the flow path switch 240, the internal heat exchanger 260, the second branch BP2, and the compressor 230.

FIG. 2 is a diagram showing the configuration of the air conditioner 1100 of the reference example.
The difference between the air conditioner 1100 of the reference example and the air conditioner 1000 of the first embodiment is that the air conditioner 1100 of the reference example has two

compressors

230A and 230B and two flow path switches 240A and 240B. The point is that two

first valves

250A and 250B are provided.

The air conditioner 1100 of the reference example is used in, for example, a train. The air conditioner 1100 of the reference example uses R407c, which is a general refrigerant. The air conditioner 1100 of the reference example uses two

compressors

230A and 230B in order to realize the required performance.

_{When the refrigerant is changed from R407c to CO 2} refrigerant without changing the housing of the air conditioner 1100 in the reference example, the theoretical efficiency of the air conditioner decreases. Therefore, the air conditioner uses an internal heat exchanger. You need to be prepared.

When _{an air conditioner using a CO 2} refrigerant is provided with two compressors as in the reference example, it is provided with two internal heat exchangers corresponding to the two compressors, or one internal heat. It is necessary to have a exchanger and a complicated control mechanism. As a result, the cost of air conditioners using _{CO 2 refrigerant increases.}

Since _{the operating pressure of an air conditioner using a CO 2} refrigerant is high, it is necessary to increase the wall thickness of the heat exchanger and the piping. As a result, _{the weight of the air conditioner using the CO 2} refrigerant becomes larger than the weight of the air conditioner 1100 of the reference example.

On the other hand, _{the volume volume of CO 2} (= latent heat of vaporization x gas density) reaches 4 to 5 times that of R407c, which is a general refrigerant, so the stroke volume of the compressor (internal volume of the compressor chamber) is greatly reduced. be able to. Therefore, _{the compressor of the air conditioner using the CO 2} refrigerant can be significantly downsized as compared with the compressor for a general refrigerant. Therefore, it is possible to reduce the number of compressors in the air conditioner using the _{CO 2 refrigerant to one.}

Therefore, from the viewpoint of performance, cost, and weight, _{the air conditioner using the CO 2} refrigerant of the present embodiment includes one compressor and one internal heat exchanger as shown in FIG.

3 and 4 are side views of the outdoor unit 200.
As shown in FIG. 3, the upper surface US of the outdoor unit 200 has an arc shape along the X-axis direction. The outdoor unit 200 has the highest central portion in the X-axis direction. In order to improve the performance of the air conditioner 1000, it is necessary to make the first outdoor heat exchanger 211 and the second outdoor heat exchanger 212 as large as possible. On the other hand, in order to improve the efficiency of heat exchange by blowing air to the first outdoor heat exchanger 211 and the second outdoor heat exchanger 212 by the outdoor blower 220, the first outdoor heat exchanger 211 and the second outdoor heat exchange are performed. It is necessary to arrange the outdoor blower 220 between the vessels 212.

The outdoor blower 220 is arranged in the center of the outdoor unit 200 in the X-axis direction. The first outdoor heat exchanger 211 is arranged on one side of the outdoor blower 220 in the X-axis direction, and the second outdoor heat exchanger 212 is arranged on the other side of the outdoor blower 220. The compressor 230 is arranged between one end E1 of the outdoor unit 200 and the first outdoor heat exchanger 211 in the X-axis direction. The internal heat exchanger 260 is arranged between the other end E2 of the outdoor unit 200 and the second outdoor heat exchanger 212 in the X-axis direction. As a result, the compressor 230 and the internal heat exchanger 260 are arranged at positions separated from each other in the X-axis direction.

As shown in FIG. 4, in the pipe 310M, the portion between the outlet of the indoor unit 100 and the first branch portion BP1 is arranged along the Y-axis direction. The first bypass pipe PB1 is arranged along the X-axis direction. By arranging the compressor 230 and the pipe 310M so that the distance between the pipe 310M and the compressor 230 is as small as possible, the length of the first bypass pipe PB1 can be changed to the length of the pipe 312M and the length of the pipe 313M. It can be smaller than that. For example, as shown in FIG. 4, the first bypass pipe PB1 is arranged between the compressor 230 and one end E1 of the outdoor unit in the X-axis direction. Here, it is assumed that the thickness of the first bypass pipe PB1, the thickness of the pipe 312M, and the thickness of the pipe 313M are all the same.

The operation of the air conditioner 1000 when the operation mode of the air conditioner 1000 is the first mode will be described.

The high-temperature and high-pressure refrigerant discharged from the compressor 230 flows into the first outdoor heat exchanger 211 and the second outdoor heat exchanger 212 via the flow path switch 240.

In the first outdoor heat exchanger 211 and the second outdoor heat exchanger 212, the refrigerant dissipates heat by exchanging heat with the outdoor air blown by the outdoor blower 220.

After that, the refrigerant is depressurized at the first valve 250 and becomes a gas-liquid two-phase state. The gas-liquid two-phase refrigerant passes through the internal heat exchanger 260 and flows into the first chamber heat exchanger 111 and the second chamber heat exchanger 112.

In the first indoor heat exchanger 111 and the second indoor heat exchanger 112, the refrigerant absorbs heat by exchanging heat with the external air blown by the indoor blower 120, and becomes a gas state.

The gas-state refrigerant reaches the first branch BP1. In the first mode, since the second valve 280 is open, the flow paths from the first branch BP1 to the second branch BP2 on the suction side of the compressor 230 include the first flow path 11 and the second flow. There is a road 12.

The first flow path 11 is a flow path that passes through the first bypass pipe PB1 and the second valve 280. The second flow path 12 is a flow path that passes through the pipe 311M, the flow path switch 240, the pipe 312M, the internal heat exchanger 260, and the pipe 313M.

As shown in FIG. 4, by making the length of the first bypass pipe PB1 smaller than the length of the pipe 312M and the length of the pipe 313M, the flow path resistance LR2 of the second flow path 12 becomes the first flow path. It becomes larger than the flow path resistance LR1 of 11.

Therefore, therefore, when the flow rate of the refrigerant in the gas state reaching the first branch portion BP1 is F1, the flow rate of the refrigerant flowing in the first flow path 11 is F1 × a1 and flows in the second flow path 12. The flow rate of the refrigerant is F1 × a2. a1> a2.

a1 = LR2 / (LR1 + LR2) ... (1)
a2 = LR1 / (LR1 + LR2) ... (2)
In the second branch portion BP2, the refrigerant flowing through the first flow path 11 and the refrigerant flowing through the second flow path 12 merge and are sucked into the compressor 230. Since a large amount of refrigerant flows through the first flow path 11 having a small flow path resistance, the amount of decrease in the pressure of the second branch portion BP2 from the pressure of the first branch portion BP1 can be reduced. As a result, the performance of the air conditioner 1000 can be improved.

In the first mode, the internal heat exchanger 260 contains a gas-liquid two-phase refrigerant (refrigerant A) from the first valve 250 and a refrigerant (refrigerant) flowing from the second heat exchange unit 110 to the second flow path 12. B) and are inflowed. The flow rate of the refrigerant B is small, and both the refrigerant A and the refrigerant B are decompressed refrigerants. Therefore, in the internal heat exchanger 260, the refrigerant A and the refrigerant B hardly exchange heat. Therefore, in the first mode, the internal heat exchanger 260 is not used.

Next, the operation of the second mode in which the operation mode of the air conditioner 1000 is set will be described.
The high-temperature and high-pressure refrigerant discharged from the compressor 230 reaches the first branch portion BP1 via the flow path switch 240. In the second mode, since the second valve 280 is closed, the refrigerant does not flow into the first flow path 11, but flows into the first chamber heat exchanger 111 and the second chamber heat exchanger 112. The liquid refrigerant radiated in the first chamber heat exchanger 111 and the second chamber heat exchanger 112 is further cooled in the internal heat exchanger 260.

After that, the refrigerant is depressurized in the first valve 250, becomes a gas-liquid two-phase state, and flows into the first outdoor heat exchanger 211 and the second outdoor heat exchanger 212. The refrigerant absorbed in the first outdoor heat exchanger 211 and the second outdoor heat exchanger 212 passes through the flow path switch 240 and flows into the internal heat exchanger 260. The refrigerant is heated in the internal heat exchanger 260 to become a gas refrigerant. After that, the refrigerant is sucked into the compressor 230 via the second branch portion BP2.

In the second mode, in the internal heat exchanger 260, the liquid refrigerant (refrigerant C) from the first indoor heat exchanger 111 and the second indoor heat exchanger 112 and the first outdoor heat exchanger 211 and the second outdoor heat exchanger are exchanged. The refrigerant (refrigerant D) from the vessel 212 exchanges heat. The refrigerant C is cooled by dissipating heat to the refrigerant D. The refrigerant D is heated by absorbing heat from the refrigerant C. Therefore, in the second mode, the internal heat exchanger 260 is effectively used.

Next, the operation of the air conditioner 1000 when the operation mode of the air conditioner 1000 is the third mode will be described.

The gas-state refrigerant reaches the first branch BP1. In the third mode, since the second valve 280 is closed, the only flow path from the first branch BP1 to the second branch BP2 on the suction side of the compressor 230 is the second flow path 12. The second flow path 12 is a flow path that passes through the pipe 311M, the flow path switch 240, the pipe 312M, the internal heat exchanger 260, and the pipe 313M.

The refrigerant flowing through the second branch BP2 is sucked into the compressor 230.
In the third mode, the internal heat exchanger 260 contains a gas-liquid two-phase refrigerant (refrigerant A) from the first valve 250 and a refrigerant (refrigerant) flowing from the second heat exchange unit 110 to the second flow path 12. B) and are inflowed. Both the refrigerant A and the refrigerant B are decompressed refrigerants. Therefore, in the internal heat exchanger 260, the refrigerant A and the refrigerant B hardly exchange heat. Therefore, in the third mode, the internal heat exchanger 260 is not used.

In the third mode, the gaseous refrigerant absorbed from the outside air in the first chamber heat exchanger 111 and the second chamber heat exchanger 112 flows through the second flow path 12 having a large flow path resistance, so that the compressor 230 A large pressure drop occurs on the suction side. As a result, the circulating flow rate of the refrigerant is reduced, so that the cooling capacity of the air conditioner 1000 is reduced. Therefore, when the outside air temperature exceeds the specified value, the high pressure pressure discharged by the compressor 230 can be reduced by setting the air conditioner 1000 to the third mode, so that the discharge pressure of the compressor 230 is high. Therefore, it is possible to prevent the protection operation from being executed.

According to the present embodiment, from the viewpoint of cost, weight, and the like, an internal heat exchanger is used at the time of heating operation in an air conditioner _{including one compressor and using a CO 2 refrigerant.} Thereby, the performance of the air conditioner can be improved. In this air conditioner, a bypass path provided with a solenoid valve is provided in a portion where the low-pressure refrigerant flows during the cooling operation. As a result, the pressure loss in the low pressure portion can be reduced, so that the efficiency of the air conditioner can be increased.

Embodiment 2.
FIG. 5 is a diagram showing the configuration of the air conditioner 1001 of the second embodiment.

The difference between the air conditioner 1001 of FIG. 5 and the air conditioner 1000 of the embodiment of FIG. 1 is as follows.

The refrigerant circuit RC2 of the air conditioner 1001 of FIG. 5 includes a second bypass pipe 271 and a third valve 270.

The third valve is between the third branch BP3 between the first valve 250 and the internal heat exchanger 260 and the fourth branch BP4 between the internal heat exchanger 260 and the second heat exchanger 110. It is connected by the second bypass pipe 271 via 270.

The third valve 270 is composed of, for example, a check valve. The check valve allows the flow of the refrigerant from the third branch BP3 to the fourth branch BP4 to pass, and shuts off the flow of the refrigerant from the fourth branch BP4 to the third branch BP3.

When the operation mode of the air conditioner 1001 is the first mode and the third mode, the refrigerant flows through the second bypass pipe 271 by the third valve 270, and when the operation mode of the air conditioner 1001 is the second mode, Refrigerant does not flow through the second bypass pipe 271.

The operation of the air conditioner 1001 when the operation mode of the air conditioner 1001 is the first mode will be described.

After that, the refrigerant is depressurized at the first valve 250, becomes a gas-liquid two-phase state, and reaches the third branch portion BP3. Most of the gas-liquid two-phase state refrigerant that has reached the third branch BP3 passes through the second bypass pipe 271 and the third valve 270 and reaches the fourth branch BP4. The rest of the gas-liquid two-phase state refrigerant that has reached the third branch BP3 reaches the fourth branch BP4 via the internal heat exchanger 260. The refrigerants in the two flow paths merged in the fourth branch BP4 flow into the first chamber heat exchanger 111 and the second chamber heat exchanger 112.

After that, in the first indoor heat exchanger 111 and the second indoor heat exchanger 112, the refrigerant absorbs heat by exchanging heat with the external air blown by the indoor blower 120, and becomes a gas state.

The gas-state refrigerant reaches the first branch BP1. In the first mode, since the second valve 280 is open, the refrigerant in the gas state passes from the first branch portion BP1 through the first flow path 11 and the second flow path 12, and is the first, as in the first embodiment. 2 Reach the branch BP2. However, since the flow path resistance of the first flow path 11 is smaller than the flow path resistance of the second flow path 12, most of the refrigerant in the gas state flows through the first flow path 11. In the second branch portion BP2, the refrigerant flowing through the first flow path 11 and the refrigerant flowing through the second flow path 12 merge and are sucked into the compressor 230.

Next, the operation of the air conditioner 1001 when the operation mode of the air conditioner 1001 is the second mode will be described.

The high-temperature and high-pressure refrigerant discharged from the compressor 230 reaches the first branch portion BP1 via the flow path switch 240. In the second mode, since the second valve 280 is closed, the refrigerant does not flow into the first flow path 11, but flows into the first chamber heat exchanger 111 and the second chamber heat exchanger 112. The liquid refrigerant radiated in the first chamber heat exchanger 111 and the second chamber heat exchanger 112 does not flow through the second bypass pipe 271 and the third valve 270, and the internal heat exchanger 260 is the same as in the first embodiment. Inflow to. The refrigerant is further cooled in the internal heat exchanger 260.

Next, the operation of the air conditioner 1001 when the operation mode of the air conditioner 1001 is the third mode will be described.

The gas-state refrigerant reaches the first branch BP1. In the third mode, since the second valve 280 is closed, the refrigerant flows from the first branch portion BP1 to the second branch portion BP2 via the second flow path 12. The refrigerant flowing through the second branch BP2 is sucked into the compressor 230.

In the second embodiment, in the first mode and the third mode, most of the refrigerant discharged from the first valve 250 does not go through the internal heat exchanger 260, but the first chamber heat exchanger 111 and the second chamber. It flows into the heat exchanger 112. This makes it possible to reduce the drop in pressure due to passing through the internal heat exchanger 260.

When the outside air temperature is very high during cooling operation, the temperature of the refrigerant discharged from the second heat exchange unit 110 becomes too high because the amount of refrigerant circulating is large. In order to avoid this, the opening degree of the first valve 250 is controlled in the opening direction. When the opening degree of the first valve 250 reaches the full opening, the temperature of the refrigerant discharged from the second heat exchange unit 110 cannot be lowered. In the second embodiment, most of the refrigerant discharged from the first valve 250 flows into the second heat exchanger 110 without passing through the internal heat exchanger 260, so that the opening degree of the first valve 250 is increased. Even when the full throttle is reached, it is possible to prevent the discharge temperature of the compressor 230 from exceeding the limit value and the protection operation being executed.

As the third valve 270, a solenoid valve may be used instead of the check valve.
Embodiment 3.
FIG. 6 is a diagram showing the configuration of the air conditioner 1002 of the third embodiment.

The difference between the air conditioner 1002 of FIG. 6 and the air conditioner 1000 of the embodiment of FIG. 1 is as follows.

The refrigerant circuit RC3 of the air conditioner 1002 of the third embodiment has a fourth valve 251 arranged in a pipe 316M which is a part of the main pipe PM between the internal heat exchanger 260 and the second heat exchanger 110. Be prepared.

The fourth valve 251 is composed of an electronic expansion valve.
When the operation modes of the air conditioner 1002 are the first mode and the second mode, the fourth valve 251 is fully opened. As a result, the air conditioner 1002 of the third embodiment operates in the same manner as that of the first embodiment.

When the operation mode of the air conditioner 1002 is the third mode, the first valve 250 is fully opened, and the fourth valve 251 depressurizes the refrigerant flowing through the pipe 316M.

When the operation mode of the air conditioner 1002 is the first mode (cooling operation mode) and the outside air temperature exceeds the specified value, the operation mode of the air conditioner 1002 is switched to the third mode (high load cooling operation mode).

When the outside air temperature is very high, the liquid refrigerant can be accumulated in the internal heat exchanger 260 by setting the air conditioner 1002 to the high load cooling operation mode. As a result, the high-pressure pressure discharged by the compressor 230 can be reduced, so that it is possible to avoid executing the protection operation due to the high discharge pressure of the compressor 230.

Modification example.
The present disclosure is not limited to the above embodiment, and includes, for example, the following modifications.

(1) In the above embodiment, the first heat exchange unit 210 and the second heat exchange unit 110 each include two heat exchangers, but the present invention is not limited thereto. The first heat exchange unit 210 and the second heat exchange unit 110 may each include one heat exchanger.

(2) Instead of arranging the first bypass pipe PB1 between the compressor 230 and one end E1 of the outdoor unit in the X-axis direction, the following may be used. In the X-axis direction, the first bypass pipe PB1 may be arranged between the compressor 230 and the first outdoor heat exchanger 211.

(3) It is assumed that the frequency of the compressor does not change when the operation modes of the

air conditioners

1000, 1001 and 1002 change from the first mode to the third mode, but the present invention is not limited to this. When the operation modes of the

air conditioners

1000, 1001 and 1002 change from the first mode to the third mode, the frequency of the compressor is changed and the control described in the first to third embodiments is executed. May be.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present disclosure is indicated by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope of the claims.

11 1st flow path, 12 2nd flow path, 100 indoor unit, 110 2nd heat exchange unit, 111 1st indoor heat exchanger, 112 2nd indoor heat exchanger, 120 indoor blower, 200 outdoor unit, 210 1st Heat exchanger, 211 1st outdoor heat exchanger, 212 2nd outdoor heat exchanger, 220 outdoor blower, 230, 230A, 230B compressor, 240, 240A, 240B flow path switch, 250, 250A, 250B 1st valve , 251 4th valve, 260 internal heat exchanger, 261a 1st internal flow path, 261b 2nd internal flow path, 270 3rd valve, 271 2nd bypass piping, 280 2nd valve, 310M, 311M, 312M, 313M, 314M, 315M, 316M, 317M, 318M piping, 1000, 1001, 1002, 1100 air conditioner, BP1 1st branch, BP2 2nd branch, BP3 3rd branch, BP4 4th branch, E1 outdoor unit One end, the other end of the E2 outdoor unit, P1 first opening, P2 second opening, P3 third opening, P4 fourth opening, PB1 first bypass pipe, RC1, RC2 refrigerant circuit, US upper surface.

Claims

It ’s an air conditioner,
It includes a compressor, a flow path switch, a first heat exchanger, a second heat exchanger, an internal heat exchanger, a first valve, and a second valve, and includes a refrigerant circuit through which a refrigerant flows.
The flow path switch includes a first opening, a second opening, a third opening, and a fourth opening.
The internal heat exchanger includes a first internal flow path and a second internal flow path.
The discharge side of the compressor and the first opening of the flow path switch are connected to each other.
One end of the first heat exchange section and the fourth opening of the flow path switch are connected to each other.
The other end of the first heat exchange portion and one end of the first valve are connected to each other.
The other end of the first valve and one end of the first internal flow path of the internal heat exchanger are connected.
The other end of the first internal flow path of the internal heat exchanger and one end of the second heat exchange portion are connected to each other.
One end of the second internal flow path of the internal heat exchanger and the second opening of the flow path switch are connected to each other.
The other end of the second heat exchange portion and the first branch portion are connected to each other.
The first branch portion, one end of the second valve, and the third opening of the flow path switch are connected to each other.
The other end of the second valve and the second branch portion are connected to each other.
The second branch portion is connected to the suction side of the compressor and the other end of the second internal flow path of the internal heat exchanger.
When the operation mode of the air conditioner is the first mode, the second valve is opened, the first opening is connected to the fourth opening, and the second opening and the third opening are connected to each other. connection,
When the operation mode of the air conditioner is the second mode, the second valve is closed, the first opening is connected to the third opening, and the second opening and the fourth opening are connected to each other. An air conditioner to connect.
When the operation mode of the air conditioner is the first mode, the compressor, the flow path switch, the first heat exchange unit, the first valve, the internal heat exchanger, the second heat exchange unit, and the first mode. The refrigerant flows in the order of one branch, then a part of the refrigerant flows through the first flow path from the first branch to the second branch via the second valve, and the rest of the refrigerant flows. It flows from the first branch portion through the flow path switcher and the internal heat exchanger to the second branch portion, and then at the second branch portion, the refrigerant of the first flow path and the refrigerant of the first flow path are described. The refrigerant in the second flow path merges and flows to the compressor.
When the operation mode of the air conditioner is the second mode, the compressor, the flow path switch, the second heat exchange unit, the internal heat exchanger, the first valve, the first heat exchange unit, and the above. The air conditioner according to claim 1, wherein the refrigerant flows in the order of the flow path switch, the internal heat exchanger, the second branch portion, and the compressor.
The air conditioner according to claim 2, wherein the flow path resistance of the first flow path is smaller than the flow path resistance of the second flow path.
The refrigerant circuit includes a main pipe and a first bypass pipe.
Between the compressor and the flow path switch, between the flow path switch and the first heat exchange section, and between the first heat exchange section and the internal heat exchanger via the first valve. Between the internal heat exchanger and the second branch, between the second branch and the compressor, between the internal heat exchanger and the second heat exchanger, the second heat. A main pipe is connected between the switching section and the first branch section, between the first branch section and the flow path switch, and between the flow path switch and the internal heat exchanger. The air exchanger according to claim 3, wherein a first bypass pipe is connected between the first branch portion and the second branch portion via the second valve.
The length of the first bypass pipe is shorter than the length of the pipe between the flow path switch and the internal heat exchanger, and the length of the pipe between the internal heat exchanger and the second branch portion is short. The air conditioner according to claim 4, which is shorter than the length.
The air conditioner according to claim 5, wherein the first heat exchange unit includes a first outdoor heat exchanger and a second outdoor heat exchanger.
The compressor, the first outdoor heat exchanger, the second outdoor heat exchanger, the outdoor blower, the internal heat exchanger, and the first valve are housed in the outdoor unit.
The upper surface of the outdoor unit has an arc shape along the first axial direction.
The outdoor blower is arranged in the center of the outdoor unit in the first axial direction.
The first outdoor heat exchanger is arranged on one side of the outdoor blower in the first axial direction, and the second outdoor heat exchanger is arranged on the other side of the outdoor blower.
The compressor is arranged between one end of the outdoor unit and the first outdoor heat exchanger in the first axial direction.
The air conditioner according to claim 6, wherein the internal heat exchanger is arranged between the other end of the outdoor unit and the second outdoor heat exchanger in the first axial direction.
The first bypass pipe is arranged parallel to the first axis.
The air conditioner according to claim 7, wherein the first bypass pipe is arranged between the compressor and the one end of the outdoor unit in the first axial direction.
The air conditioner according to claim 8, wherein a part of the main pipe connected to the first branch portion is arranged in parallel with the second axis in the direction perpendicular to the first axis.
The air conditioner according to any one of claims 1 to 9, wherein the second heat exchanger includes a first chamber heat exchanger and a second chamber heat exchanger.
The refrigerant circuit includes a second bypass pipe and a third valve.
A third valve is provided between the third branch between the first valve and the internal heat exchanger and the fourth branch between the internal heat exchanger and the second heat exchanger. It is connected by the second bypass pipe via the above-mentioned second bypass pipe.
By the third valve, when the operation mode of the air conditioner is the first mode, the refrigerant flows through the second bypass pipe, and when the operation mode of the air conditioner is the second mode, the third valve. 2. The air conditioner according to any one of claims 4 to 10, wherein the refrigerant does not flow through the bypass pipe.
When the operation mode of the air conditioner is the third mode, the second valve is closed, the first opening and the fourth opening are connected, and the second opening and the third opening are connected to each other. The air conditioner according to any one of claims 1 to 11, which is connected.
When the operation mode of the air conditioner is the third mode, the compressor, the flow path switch, the first heat exchange unit, the first valve, the internal heat exchanger, the second heat exchange unit, and the above. The air conditioner according to claim 12, wherein all the refrigerant flows in the order of the first branch portion, the flow path switch, the internal heat exchanger, the second branch portion, and the compressor.
A fourth valve arranged in the main pipe between the internal heat exchanger and the second heat exchanger is provided.
When the operation modes of the air conditioner are the first mode and the second mode, the fourth valve is fully opened.
The air conditioner according to any one of claims 4 to 9, wherein the operation mode of the air conditioner is the third mode, the first valve is fully opened, and the fourth valve depressurizes the refrigerant.
The air conditioner according to any one of claims 12 to 14, wherein the operation mode of the air conditioner changes from the first mode to the third mode when the outside air temperature exceeds a specified value.
The air conditioner according to claim 15, wherein the frequency of the compressor does not change when the outside air temperature exceeds the specified value.
The air conditioner according to any one of claims 1 to 16, wherein the refrigerant is a CO 2 refrigerant.