WO2006057141A1

WO2006057141A1 - Air conditioner

Info

Publication number: WO2006057141A1
Application number: PCT/JP2005/020109
Authority: WO
Inventors: Shinichi Wakamoto; Tomohiko Kasai; Jiro Okajima; Toshiyuki Nakamura; Kunio Tojo; Takashi Okazaki; Toshihiko Enomoto
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2004-11-25
Filing date: 2005-11-01
Publication date: 2006-06-01
Also published as: CN101065623B; JPWO2006057141A1; US20090145151A1; JP4752765B2; EP1816416B1; CN101065623A; EP1816416A1; EP1816416A4

Abstract

An air conditioner of a first mode of the invention has an outdoor unit, indoor units, and a relay section. The outdoor unit has an outdoor heat exchanger provided so as to fluidically communicate between a first and a second connection end, a compressor for discharging carbon dioxide or a refrigerant whose main component is carbon dioxide, and a first switching section for switching the direction of a refrigerant flowing in the outdoor heat exchanger. The indoor units each have an indoor heat exchanger installed so as to fluidically communicate between a first and a second piping connection section and each further have a first flow rate control section for controlling the quantity of a refrigerant flowing in the indoor heat exchanger. The relay section has second switching sections for selectively connecting the first piping connection sections of the indoor units to either of the first and the second connection end of the outdoor unit, first bypass piping for connection between the second pipe line connection section of each indoor unit and the second connection end of the outdoor unit, and a second flow rate control section provided in the first bypass piping.

Description

Specification

Air conditioner

Technical field

[0001] The present invention generally relates to an air conditioner using a refrigeration cycle. In particular, the present invention includes a mode in which one outdoor unit and a plurality of indoor units are provided and all the plurality of rooms are simultaneously cooled or heated, and a mode in which one room is cooled and another room is simultaneously heated. This relates to a multi-room air conditioner.

Background art

[0002] An outdoor unit having a compressor and an outdoor heat exchanger, a plurality of indoor units each having an indoor heat exchanger, and a relay unit for connecting the outdoor unit and the indoor unit are provided. Cooling or heating mode (cooling operation mode and heating operation mode), and a mode in which one room is cooled and another room is heated at the same time (the cooling-main operation mode and the heating operation capacity are larger than the heating operation capacity) Patent Document 1 discloses a multi-room air conditioner having a heating-main operation mode larger than the cooling operation capacity.

[0003] This conventional apparatus requires a gas-liquid separation device for separating the refrigerant that has been brought into the gas-liquid two-phase state by the outdoor heat exchanger of the outdoor unit into the refrigerant vapor and the refrigerant liquid in the cooling main operation mode. To do. The first bypass pipe, one end of which is connected to the liquid phase side end of the gas-liquid separator, is branched at the other end and connected to the flow control device of each indoor unit. The flow control device for the room that performs cooling depressurizes the high-pressure refrigerant liquid, changes it into a low-temperature low-pressure gas-liquid two-phase refrigerant, and supplies it to the indoor heat exchanger. The refrigerant vapor is supplied to the indoor unit of the room to be heated.

Patent Document 1: Japanese Patent Laid-Open No. 9-42804

Disclosure of the invention

Problems to be solved by the invention

[0004] Gas-liquid separation device force Since the refrigerant liquid that has flowed out is a saturated liquid, it is slightly depressurized until it reaches the flow control device of the indoor unit and changes into a gas-liquid two-phase state without being supercooled. And the flow Sound and pressure pulsation occur in the quantity control device. In order to prevent or prevent this, that is, in order to supercool the saturated refrigerant liquid, a second bypass pipe connected to the first bypass pipe is additionally provided, and the refrigerant liquid that also has the gas-liquid separator power is provided. A part of the gas flows from the first bypass pipe into the second bypass pipe and is reduced by the flow control device interposed in the second bypass pipe to obtain a low-temperature and low-pressure gas-liquid two-phase refrigerant. The refrigerant liquid in the first bypass pipe coming out of the gas-liquid separator is supercooled by the refrigerant in the pipe. Further, in the gas-liquid separator, in order to control the flow rate of the refrigerant liquid flowing out from the gas-liquid separator so that the refrigerant liquid is not mixed into the refrigerant vapor, the flow control device is connected to the pipe connected to the apparatus. A device is provided.

As described above, the conventional air conditioner has a very large number of parts in the relay section. In addition, since there are many flow control devices, it is difficult to control the cooling / heating capacity of the indoor heat exchanger. Furthermore, in the above-described air conditioner, the greenhouse effect gas as a refrigerant is measured based on the global warming potential (a measure of the effect on global warming, with carbon dioxide as the standard (= 1)). The numerical value indicating the degree of global warming is high, and chlorofluorocarbons are used.

[0006] Therefore, one aspect of the present invention uses carbon dioxide or a refrigerant mainly composed of carbon dioxide as the refrigerant, greatly reduces the number of parts in the relay section, and controls the heating and cooling capacity in indoor heat exchange. Provided is a multi-chamber air conditioner that facilitates the above.

Means for solving the problem

In order to achieve the above object, an air conditioner according to one aspect of the present invention includes an outdoor unit, a plurality of indoor units, and a relay unit that connects the outdoor unit and each indoor unit. The outdoor unit includes an outdoor heat exchanger disposed to fluidly communicate between the first and second connection ends, a compressor that compresses and discharges carbon dioxide or a refrigerant mainly composed of carbon dioxide, And a first switching unit that switches the direction of the refrigerant flowing in the outdoor heat exchanger. Each indoor unit includes an indoor heat exchanger arranged to fluidly communicate between the first and second pipe connections, and a first flow rate control unit for controlling the amount of refrigerant flowing through the indoor heat exchanger Have The relay unit includes a plurality of second switching units and indoor units for selectively connecting each first pipe connection of the indoor unit to one of the first and second connection ends of the outdoor unit. Each second plumbing connection and chamber A first no-pass pipe connecting between the second connection ends of the outer unit, and a second flow rate control unit interposed in the first bypass pipe.

The invention's effect

[0008] According to the present invention, in the cooling main operation mode, the refrigerant passes through the refrigerant discharge port of the compressor, the first switching unit, the outdoor heat exchanger, and the second connection end. Then, the air flows into the indoor unit that performs the heating operation, and the air is heated by the indoor heat exchanger of the indoor unit. After that, the refrigerant flows into the indoor unit that performs cooling, passes through the first flow rate control unit of the indoor unit, and is depressurized. Then, the refrigerant is cooled by the indoor heat exchanger, and the first connection terminal Head to the club. The supercritical state is maintained for the refrigerant composed mainly of diacid-carbon or simple substance of carbon dioxide until it reaches the first flow control part of the indoor unit that performs cooling from the refrigerant outlet of the compressor. Therefore, it is possible to suppress or prevent the generation of sound and pressure pulsation that may occur in the first flow control unit. As described above, according to the present invention, since the supercritical state of the refrigerant is maintained, it is necessary to provide a gas-liquid separation device and a component associated therewith as in a conventional air conditioner. The score can be greatly reduced. In addition, because the number of flow control units is less than the conventional configuration, V, the control of the cooling / heating capacity of the indoor heat exchanger becomes easy.

Brief Description of Drawings

FIG. 1 is a refrigerant circuit diagram showing Embodiment 1 of an air-conditioning apparatus according to the present invention.

FIG. 2 is a view similar to FIG. 1, showing refrigerant circulation in the cooling operation mode.

FIG. 3 is a view similar to FIG. 1, showing refrigerant circulation in the heating operation mode.

FIG. 4 is a view similar to FIG. 1, showing refrigerant circulation in the cooling main operation mode.

FIG. 5 is a view similar to FIG. 1, showing refrigerant circulation in the heating main operation mode.

[Fig. 6] A ph diagram (pressure-enthalpy diagram) showing the transition of refrigerant circulation in Fig. 2.

FIG. 7 is a ph diagram showing the transition of refrigerant circulation in FIG.

FIG. 8 is a ph diagram showing the change of refrigerant circulation in FIG.

FIG. 9 is a ph diagram showing the transition of refrigerant circulation in FIG.

FIG. 10 is a refrigerant circuit diagram of an air conditioner shown as a comparative example.

FIG. 11 is a refrigerant circuit diagram showing Embodiment 2 of the air-conditioning apparatus according to the present invention.

FIG. 12 is a view similar to FIG. 11 and shows a modification of the second embodiment. Explanation of symbols

[0010] 2 Air conditioner

4 Outdoor unit

6P-6R indoor unit

8 Relay section

10 Compressor

10a Refrigerant outlet

10b Refrigerant inlet

12 Heat exchanger (outdoor heat exchanger)

16 1st switching part (4-way switching valve)

18a, 18b First and second piping (inter-unit piping)

20a, 20b first and second connection ends

22P to 22R Second switching section

26a, 26b 1st and 2nd piping connections

28 Heat exchanger (indoor heat exchanger)

32P to 32R Flow control valve (First flow control unit)

34 First bypass piping

36 Flow control valve (second flow control unit)

52 Channel switching section

66 Second bypass piping

68 Flow control valve (third flow control unit)

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0012] Embodiment 1.

FIG. 1 shows Embodiment 1 of an air-conditioning apparatus according to the present invention. The air conditioner 2 uses carbon dioxide as a refrigerant, and includes an outdoor unit 4, a plurality of indoor units 6, and a relay unit 8 that connects the outdoor units and the indoor units. In this embodiment, the number of indoor units 6 is three (units 6P, 6Q, 6R). The invention is not limited.

[0013] The air conditioner 2 has a cooling operation mode in which all the rooms in which the indoor units 6P to 6R are arranged are cooled, a heating operation mode in which all the rooms are heated, and a room is cooled and at the same time another room is heated. There are two modes (cooling main operation mode and heating main operation mode).

The outdoor unit 4 includes a compressor 10 for compressing a refrigerant, a heat exchanger (outdoor heat exchanger) 12 and a first switching unit (for example, a four-way valve) 16, which are the first and first units. The two connection ends 20a and 20b are arranged to be in fluid communication. The refrigerant discharge port 10a and the refrigerant suction port 10b of the compressor 10 are connected to the first switching unit 16 via pipes 14a and 14b, respectively. One end 12a of the heat exchanger 12 is connected to the first switching unit 16 via a pipe 14c. A pipe 14d is also connected to the switching unit 16. The pipe 14d extends to the pipe connection part (first connection end part) 20a of the outdoor unit 4 to which one end of the pipe 18a of the relay part 8 is connected. The other end 12b of the heat exchange is connected to the pipe 14e. The pipe 14e extends to the pipe connection part 20b of the outdoor unit 4 to which one end of the pipe 18b between the relay part 8 is connected. That is, the pipes 18a and 18b are inter-unit pipes for connecting the outdoor unit 4 and the indoor units 6P to 6R.

[0015] The switching unit 16 is configured to be able to switch the direction of the refrigerant flowing in the heat exchanger 12 between the first and second flow states according to the operation mode. In the first state, as shown in FIG. 2, the pipe connecting portion 20a is connected to the refrigerant suction port 1 Ob of the compressor 10 via the pipes 14d and 14b, and the refrigerant discharge port 10a of the compressor 10 is connected to the pipes 14a and 14a. The refrigerant is connected to one end 12a of the heat exchanger 12 through 14c, and at this time, the refrigerant flows from one end 12a to the other end 12b of the heat exchanger, that is, from the pipe connecting portions 20a to 20b. On the other hand, in the second state, as shown in FIG. 3, one end 12a of the heat exchanger 12 is connected to the refrigerant suction port 10b of the compressor 10 via the pipes 14c and 14b, and the refrigerant discharge port 10a of the compressor 10 is connected. Is connected to the pipe connection portion 20a via the pipes 14a and 14d, and at this time, the refrigerant flows from the other end 12b of the heat exchange to the one end 12a, that is, from the pipe connection portions 20b to 20a.

The relay unit 8 includes the same number of three-way switching valves 22 having three connection ports 24a, 24b, and 24c as the indoor unit 6 (three in this embodiment, 22P, 22Q, and 22R). Piping 18a The side opposite to the side connected to the connecting portion 20a is branched into three, and is connected to the connecting port 24a of each three-way switching valve 22. Similarly, the pipe 18b is branched into three on the opposite side to the side connected to the pipe connection portion 20b, and is connected to the connection port 24b of each three-way switching valve 22. The connection port 24c is connected to the first pipe connection part 26a of the corresponding indoor unit 6 through the pipe.

[0017] Each indoor unit 6 includes a heat exchanger (indoor heat exchanger) 28 and a flow control valve (first flow control unit) 32 (32P, 32Q, 32R). The pipe connection portions 26a and 26b are arranged in fluid communication. In particular, one end 28a of the heat exchanger 28 is connected to the pipe connection part 26a via a pipe, and the other end 28b is connected to the second pipe connection part 26b via a pipe 30 to be connected to the second pipe. The connection part 26b is connected to the bypass pipe 34 of the relay part 8. A first flow rate control unit 32 (32P, 32Q, 32R) for controlling the flow rate of the refrigerant flowing through the pipe 30 is provided in the middle of the pipe 30 of each indoor unit 6P, 6Q, 6R.

[0018] One end of the relay section 8 is connected in the middle of the pipe 18b, and a bypass connected to the pipe connection section 26b of each indoor unit 6 (and hence the flow control device 32) is branched at the other end side. Piping 34 is provided. A second flow rate control unit 36 for controlling the flow rate of the refrigerant flowing through the piping is provided in the middle of the noise piping 34.

[0019] Next, the operation of each operation mode of the air conditioner 2 having a powerful configuration is shown in Figs. 2 to 5 and the ph diagram (relationship between the refrigerant pressure and the enthalbi) showing the flow direction of the refrigerant. This will be described with reference to FIGS. In Fig. 2 to Fig. 5, the thick line indicates the piping where the refrigerant has moved during operation, and the numbers [i] (i = l, 2,...) In parentheses are the diagrams in Fig. 6 to Fig. 9. The piping part corresponding to the upper point i (each state of the refrigerant) is shown.

[0020] Cooling operation mode (Fig. 2 and Fig. 6)

When all the indoor units 6P to 6R perform cooling operation, the switching unit 16 is in the first flow state (the refrigerant discharge port 10a of the compressor 10 is connected to one end 12a of the heat exchanger 12, and the refrigerant suction port 10b is connected to the pipe connection unit. Switch to 20a), fully open the flow control valve 36, and throttle the flow control valves 32P to 32R. Further, the connection port 24b of each three-way switching valve 22 is closed, and the connection ports 24a and 24c are opened. In this state, the operation of the compressor 10 is started.

[0021] First, the low-temperature and low-pressure refrigerant vapor is compressed by the compressor 10 and discharged as a high-temperature and high-pressure refrigerant. Is issued. The refrigerant compression in the compressor 10 is represented by an isentropic curve (point [1], point [2]) in the ph diagram of FIG. 6 assuming that heat does not enter and exit from the surroundings.

[0022] The high-temperature and high-pressure refrigerant discharged from the compressor 10 passes through the switching unit 16, and the temperature decreases while heating the air or the like in the heat exchanger 12. The change of the refrigerant in the heat exchanger 12 is performed under almost constant pressure, but considering the pressure loss of the heat exchanger 12, a line close to a slightly inclined horizontal line in the ph diagram ( It is represented by point [2] —point [3]). Unlike CFC-based refrigerants, carbon dioxide is supercritical at high pressure, so it heats the air as the temperature drops without condensing.

[0023] The high-pressure refrigerant from the heat exchange passes through the pipe connection part 20b and the bypass pipe 34 (the flow control valve 36 is fully open), branches and flows into the indoor units 6P to 6R. It is throttled and expanded (decompressed) at 32R, resulting in a gas-liquid two-phase state at low temperature and pressure. The change of the refrigerant in the flow control valve 32 is performed under a constant enthalpy and is represented by a vertical line (point [3] -point [4]) in the ph diagram.

[0024] The refrigerant in the gas-liquid two-phase state changes into low-temperature and low-pressure refrigerant vapor while cooling air or the like by heat exchange in the indoor unit 6. The change of the refrigerant in the heat exchanger 28 is performed under almost constant pressure, but considering the pressure loss of the heat exchanger 28, the line ( Point [4] is represented by one point [1]).

[0025] The low-temperature and low-pressure refrigerant vapors coming out of the heat exchange 28 of each indoor unit 6P to 6R merge after passing through each three-way switching valve 22, and the first pipe connection part 20a and the first switching part 16 are connected. Return to compressor 1 0.

[0026] Note that the refrigerant vapor flowing into the compressor 10 has a slightly lower pressure because it passes through the piping than the refrigerant vapor immediately after exiting the heat exchanger 28, but the same point on the ph diagram. It is represented by [1]. Similarly, the refrigerant flowing into the flow control valve 32 is slightly lower in pressure because it passes through the piping than the high-pressure refrigerant that has flowed out of the heat exchanger 12, but the same point on the ph diagram [3 ] The slight decrease in the refrigerant pressure caused by passing through these pipes and the pressure loss in the heat exchangers 12 and 28 described above are the same in the following heating operation mode, cooling main operation mode, and heating main operation mode. The description is omitted unless necessary.

[0027] Heating operation mode (Figures 3 and 7) When all the indoor units 6P to 6R perform heating operation, the switching unit 16 is in the second flow state (the refrigerant discharge port 10a of the compressor 10 is connected to the pipe connection unit 20a, the refrigerant suction port 10b is connected to one end 12a of the heat exchanger 12a. Connected), fully open the opening of the flow control valve 36, and reduce the opening of the flow control valves 32P to 32R. Further, the connection port 24b of each three-way switching valve 22 is closed, and the connection ports 24a and 24c are opened. In this state, the operation of the compressor 10 is started.

[0028] First, the low-temperature and low-pressure refrigerant vapor (point [1]) is compressed by the compressor 10 and discharged as a high-temperature and high-pressure refrigerant. The high-temperature and high-pressure refrigerant (point [2]) discharged from the compressor 10 passes through the switching unit 16 and the pipe connection unit 20a, branches, passes through the three-way switching valve 22, and passes through each of the indoor units 6P to 6R. It flows into heat exchange 28. The refrigerant heats air or the like by heat exchange 28 to lower its temperature (point [3]), and then is depressurized by the flow control valve 32 to change to a low-temperature low-pressure gas-liquid two-phase state (point [4] ]). Thereafter, the refrigerant that has come out of each of the indoor units 6P to 6R merges in the bypass pipe 34, passes through the pipe connection portion 20b, and flows into the other end 12b of the heat exchanger 12. The refrigerant in the gas-liquid two-phase state changes to low-temperature and low-pressure refrigerant vapor by cooling air or the like with the heat exchanger 12 (point [1]). Thereafter, the refrigerant passes through the switching unit 16 and returns to the compressor 10.

[0029] Cooling main operation mode (Fig. 4 and Fig. 8)

When the indoor units 6P and 6Q perform cooling operation and the indoor unit 6R performs heating operation, the switching unit 16 is in the first state (the refrigerant discharge port 10a of the compressor 10 is connected to one end 12a of the heat exchanger 12 and the refrigerant suction port 10b is connected). Switch to pipe connection 20a), close the flow control valve 36, throttle the flow control valve 3 2P, 32Q, and fully open the flow control valve 32R. Further, the connection ports 24b are closed and the connection ports 24a and 24c are opened for the three-way switching valves 22P and 22Q. Regarding the three-way selector valve 22R, the connection port 24a is closed and the connection ports 24b and 24c are opened. In this state, operation of the compressor 10 is started.

[0030] First, the low-temperature and low-pressure refrigerant vapor (point [1]) is compressed by the compressor 10 and discharged as a high-temperature and high-pressure refrigerant. The high-temperature and high-pressure refrigerant (point [2]) discharged from the compressor 10 passes through the switching unit 16 and decreases in temperature while heating air or the like in the heat exchanger 12 (point [3]).

[0031] The high-pressure refrigerant discharged from the heat exchanger 12 passes through the pipe connection portion 20b and the three-way switching valve 22R, flows into the indoor unit 6R, and heats the air and the like by heat exchange 28, and the temperature further decreases. (Point [4]) o The refrigerant then flows into the indoor units 6P and 6Q and is throttled by the flow control valves 32P and 32Q. It expands (depressurizes) and enters a low-temperature and low-pressure gas-liquid two-phase state (point [5]). This refrigerant further cools the air and the like by heat exchange 28 and changes to low-temperature and low-pressure refrigerant vapor (point [1]).

[0032] Refrigerant from the indoor units 6P and 6Q merges after passing through the three-way switching valves 22P and 22Q, and returns to the compressor 10 through the pipe connection portion 20a and the switching portion 16.

[0033] Carbon dioxide, which is a refrigerant, flows from the refrigerant discharge port 10a of the compressor 10 to the flow control valve 32P of the switching unit 16, the heat exchanger 12, the indoor unit 6R, the indoor unit 6P, or the indoor unit 6Q. Because the flow to the control valve 32Q is in a supercritical state (because the pressure is slightly reduced by passing through the piping, the supercritical state is maintained), the flow control valves 32P, Can suppress / prevent sound and pressure pulsation in 32Q.

[0034] By the way, FIG. 10 shows a comparative example of an air conditioner having a conventional configuration using a fluorocarbon refrigerant. This device 2 ′ includes a gas-liquid separator 40 in the middle of the pipe 18b of the relay section 8 ′, and a no-pass pipe 34 is connected to the liquid phase side of the gas-liquid separator.

[0035] When the conventional air conditioner performs the cooling main operation, that is, when the indoor units 6P and 6Q perform the cooling operation and the indoor unit 6R performs the heating operation, the switching unit 16 is set in the first flow state (compressor 10 The refrigerant discharge port 10a is switched to one end 12a of the heat exchanger 12 and the refrigerant suction port 10b is connected to the pipe connection 20a), the flow control valves 36, 32P and 32Q are throttled down, and the flow control valve 32R is fully opened. To. In addition, for the three-way switching valves 22P and 22Q, the connection port 24b is closed and the connection ports 24a and 24c are opened. With respect to the three-way switching valve 22R, the connection port 24a is closed and the connection ports 24b, 24c are opened. In this state, the operation of the compressor 10 is started.

First, the low-temperature and low-pressure fluorocarbon refrigerant vapor is compressed by the compressor 10 and discharged as a high-temperature and high-pressure refrigerant. The high-temperature and high-pressure refrigerant discharged from the compressor 10 passes through the switching unit 16 and partially heats the air and the like by heat exchange 12 (because the refrigerant flowing into the heat exchange has a pressure lower than the critical point). Condenses and changes to a high-pressure gas-liquid two-phase state. The gas-liquid two-phase refrigerant exiting from the heat exchanger 12 flows into the gas-liquid separator 40. The high-pressure refrigerant vapor that has flowed into the gas-liquid separator 40 passes through the three-way switching valve 22R, condenses by heating air or the like in the heat exchanger of the indoor unit 6R, and changes to a high-pressure refrigerant liquid. Thereafter, the refrigerant liquid passes through the fully opened flow control valve 32R. On the other hand, the high-pressure refrigerant liquid that has flowed into the gas-liquid separator 40 passes through the flow control valve 36 and then merges with the refrigerant liquid of the indoor unit 6R, and the indoor unit 6P , Flows into 6Q. In each unit 6Ρ and 6Q, the refrigerant liquid is throttled and expanded (decompressed) by the flow control valves 32Ρ and 32Q to change to a low-temperature and low-pressure gas-liquid two-phase state. It becomes low-pressure refrigerant vapor. Thereafter, the low-temperature and low-pressure refrigerant vapors coming out of the indoor units 6Ρ and 6Q join after passing through the three-way switching valves 22Ρ and 22Q, and return to the compressor 10 through the switching unit 16.

[0037] The flow rate control valve 36 controls the flow rate of the refrigerant liquid flowing out from the gas-liquid separator so that the refrigerant liquid does not enter the refrigerant vapor flowing into the indoor unit 6R from the gas-liquid separator 40. However, when passing through the flow control valve 36, the refrigerant liquid is depressurized. Further, the refrigerant liquid is depressurized while passing through the bypass pipe 34. Since the refrigerant liquid flowing out of the gas-liquid separator 40 is a saturated liquid, if it becomes a gas-liquid two-phase state due to decompression, sound and pressure pulsations will occur when it flows into the flow control valves 33Ρ and 32Q of the indoor units 6Ρ and 6Q. appear.

Therefore, in the air conditioner 2 ′, it is necessary to provide a configuration for supercooling the refrigerant liquid flowing out from the gas-liquid separator 40. Specifically, the second bypass transfer has one end connected to the downstream side of the flow control valve 36 (with respect to the flow direction of the refrigerant flowing through the first bypass pipe 34 in the cooling main operation mode) and the other end connected to the unit pipe 18a. 42 is provided. In addition, a flow control valve 44 is provided near the one end so that the refrigerant flowing from the bypass pipe 34 to a part of the bypass pipe 42 is throttled (expanded) to obtain a low-temperature and low-pressure gas-liquid two-phase refrigerant. To do so. The bypass pipe 42 is composed of a low-temperature and low-pressure gas-liquid two-phase refrigerant flowing in the interior of the bypass pipe 34 between the gas-liquid separation device 40 and the flow control valve 36 and between the flow control valve 36 and the one end. Supercool the refrigerant passing through the part in between.

[0039] As described above, when the chlorofluorocarbon refrigerant is used, the number of components of the relay unit 8 'is very large for the purpose of performing the cooling main operation mode.

[0040] On the other hand, in the present embodiment, since carbon dioxide is used as the refrigerant, the number of parts of the relay unit 8 without using the gas-liquid separator can be greatly reduced. In addition, since the number of flow control valves is small, it is easy to control the cooling / heating capacity of the indoor heat exchangers 32P to 32R.

[0041] In the cooling main operation mode of the present embodiment, the flow rate control valve 36 is closed, and the operation of the force flow rate described for the operation in which all the refrigerant flows through the indoor unit 6R for heating is performed. The increase generates refrigerant noise and pipe corrosion, so the flow control valve 36 is controlled so that a part of the refrigerant flows through the first bypass pipe 34 and flows through the indoor unit 6R. You can do it.

[0042] Heating-main operation mode (Figures 5 and 9)

When the indoor units 6P and 6Q perform heating operation and the indoor unit 6R performs cooling operation, the switching unit 16 is in the second flow state (the refrigerant discharge port 10a of the compressor 10 is connected to the pipe connection unit 20a, and the refrigerant suction port 10b is heat-exchanged. Switch to the one end 12a of the device 12), throttle the flow control valve 36, fully open the flow control valves 32P and 32Q, and throttle the flow control valve 32R. In addition, the connection port 24b is closed and the connection ports 24a and 24c are opened for the three-way switching valves 22P and 22Q. Three-way selector valve 2 For 2R, close the connecting port 24a and open the connecting ports 24b and 24c. In this state, operation of the compressor 10 is started.

[0043] First, the low-temperature and low-pressure refrigerant vapor (point [1]) is compressed by the compressor 10 and discharged as a high-temperature and high-pressure refrigerant. The high-temperature and high-pressure refrigerant (point [2]) discharged from the compressor 10 passes through the switching unit 16 and the pipe connection unit 20a, then branches and passes through the three-way switching valves 22P and 22Q, and passes through the indoor units 6P and 6Q. It flows into heat exchange 28. Refrigerant heats air or the like with heat exchanger 28 and drops in temperature (point [3]). The refrigerant that has passed through the heat exchangers 28 of the indoor units 6P and 6Q passes through the fully open flow control valves 32P and 32Q, and then partly passes through the indoor unit 6R and the rest through the bypass pipe 34.

[0044] The refrigerant flowing into the indoor unit 6R is throttled and expanded (depressurized) by the flow control valve 32R, and changes to a low-temperature and low-pressure gas-liquid two-phase state (point [4]). Subsequently, the refrigerant cools air or the like in the heat exchanger 28 of the indoor unit 6R, evaporates part or all (point [5]), and flows into the three-way switching valve 22R. Although not limited to this, in the example of FIG. 9, the refrigerant (point [5]) that has exited the heat exchange 28 is in a gas-liquid two-phase state with a dryness close to 1.0.

[0045] On the other hand, the remaining refrigerant (point [3]) that did not flow into the indoor unit 6R passes through the bypass pipe 34 and is throttled and expanded (decompressed) by the flow control valve 36, so that the low-temperature and low-pressure gas-liquid two-phase (Point [6]). Although not limited to this, in the example of FIG. 9, the refrigerant (point [6]) exiting the flow control valve 36 has a slightly lower pressure than the refrigerant exiting the heat exchanger 28 (point [5])! /.

[0046] The refrigerant exiting the flow control valve 36 is three-way (at the end of the bypass pipe 34 connected to the pipe 18b). The refrigerant that has exited the switching valve 22R merges into a gas-liquid two-phase refrigerant (point [7]). This refrigerant passes through the connection end 20b of the outdoor unit 4 and flows into the heat exchanger 12. The refrigerant in the gas-liquid two-phase state changes to low-temperature and low-pressure refrigerant vapor by cooling air and the like by heat exchange 12 (point [1]). Thereafter, the refrigerant returns to the compressor 10 through the switching unit 16.

[0047] Thus, the air conditioner of the present embodiment controls the flow rate control valve 36 in the heating main operation mode, thereby controlling the flow rate of the refrigerant flowing into the indoor unit 6R that performs the cooling operation. Can be controlled, and therefore the driving efficiency can be increased.

[0048] Embodiment 2.

FIG. 11 shows a second embodiment of the air-conditioning apparatus according to the present invention. This air conditioner 2A includes a flow path switching unit 52 in the outdoor unit 4A in addition to the configuration of the air conditioner 2 of the first embodiment. Regardless of the operation mode, the flow path switching unit 52 always causes the refrigerant carbon dioxide to flow to the outdoor unit 4A force relay unit 8A via the pipe connection unit 20b, and also to connect the relay unit force via the pipe connection unit 20a. It is for flowing to the outdoor unit.

[0049] Specifically, the flow path switching unit 52 is in the middle of the pipe 14d connecting the switching unit 16 and the pipe connection part 20a and in the middle of the pipe 14e connecting the heat exchange 12 and the pipe connection part 20b. Each has check valves 54 and 56. The check valve 54 allows the refrigerant to flow only from the pipe connection portion 20a to the switching portion 16. On the other hand, the check valve 56 allows the coolant to flow only from the heat exchanger 12 to the pipe connection portion 20b.

[0050] The flow path switching unit 52 also has one end connected to the pipe 14d portion between the switching unit 16 and the check valve 54, and the other end connected to an intermediate point of the pipe 14e between the check valve 56 and the pipe connection unit 20b. The bypass pipe 58 is provided. In the middle of the no-pass pipe 58, a check valve 60 that allows the refrigerant to flow only from the switching part 16 to the pipe connection part 20b is provided. The flow path switching unit 52 is further connected at one end to the midpoint of the pipe 14d between the pipe connection part 20a and the check valve 54 and at the other end to the pipe 14e part between the check valve 56 and the heat exchanger 12. A bypass pipe 62 is provided. In the middle of the bypass pipe 62, a check valve 64 that allows the refrigerant to flow only from the pipe connection portion 20a to the heat exchanger 12 is provided.

[0051] The relay 8A further includes a second bypass pipe 66 that connects the first bypass pipe 34 (between the flow control valve 36 and the branch portion) and the pipe 18a. Second bypass pipe 6 In the middle of 6, a third flow rate control unit 68 for controlling the flow rate of the refrigerant flowing through the pipe is provided.

[0052] Next, the operation of each operation mode of the air conditioner 2A having a powerful configuration will be described.

[0053] Cooling operation mode

When all the indoor units 6P to 6R perform cooling operation, the switching unit 16 is in the first flow state (the refrigerant discharge port 10a of the compressor 10 is connected to one end 12a of the heat exchanger 12, and the refrigerant suction port 10b is connected to the pipe connection unit. Switch to 20a), fully open the flow control valve 36, throttle the flow control valves 32P to 32R, and close the flow control valve 68. Further, the connection port 24b of each three-way switching valve 22 is closed, and the connection ports 24a and 24c are opened. In this state, start operation of the compressor 10

[0054] First, the low-temperature and low-pressure refrigerant vapor is compressed by the compressor 10 and discharged as a high-temperature and high-pressure refrigerant. The high-temperature and high-pressure refrigerant discharged from the compressor 10 passes through the switching unit 16 and falls in temperature (not condensed) while heating air or the like by heat exchange 12. The high-pressure refrigerant from the heat exchange passes through the check valve 56, the pipe connection 20b, and the bypass pipe 34 (the flow control valve 36 is fully open), branches and flows into the indoor units 6P to 6R for flow control. It is expanded (depressurized) by throttling with valves 32P to 32R, resulting in a low-temperature and low-pressure gas-liquid two-phase state. The refrigerant in the gas-liquid two-phase state changes to low-temperature and low-pressure refrigerant vapor while cooling air or the like by heat exchange in the indoor unit 6. The low-temperature and low-pressure refrigerant vapors coming out of the heat exchangers 28 of the indoor units 6P to 6R merge after passing through the three-way switching valve 22 and pass through the pipe connection part 20a. Since the refrigerant in the pipe connection 20a has a lower pressure than the refrigerant between the heat exchanger 12 and the check valve 64, it automatically passes through the check valve 54 and then passes through the switching unit 16. Return to compressor 10.

[0055] Heating operation mode

When all the indoor units 6P to 6R perform heating operation, the switching unit 16 is in the second flow state (the refrigerant discharge port 10a of the compressor 10 is connected to the pipe connection unit 20a, the refrigerant suction port 10b is connected to one end 12a of the heat exchanger 12a. Switch to), close the flow control valve 36, throttle the flow control valves 32P to 32R, and fully open the flow control valve 68. Further, the connection port 24a of each three-way switching valve 22 is closed, and the connection ports 24b and 24c are opened. In this state, the operation of the compressor 10 is started.

[0056] First, the low-temperature and low-pressure refrigerant vapor is compressed by the compressor 10 and discharged as a high-temperature and high-pressure refrigerant. Is issued. The high-temperature and high-pressure refrigerant discharged from the compressor 10 passes through the switching unit 16, the check valve 60, and the piping connection unit 20b, then branches, passes through the three-way switching valve 22, and flows into the heat exchanger 28. The The refrigerant heats air or the like by heat exchange to lower the temperature, and then is depressurized by the flow control valve 32 to change to a low-temperature and low-pressure gas-liquid two-phase state. Thereafter, the refrigerant discharged from each of the indoor units 6P to 6R joins in the first bypass pipe 34, and passes through the flow control valve 68, the second bypass pipe 66, and the pipe connection portion 20a. Since the refrigerant in the pipe connection part 20a is at a lower pressure than the refrigerant between the switching part 16 and the check valve 54, it automatically passes through the check valve 64 and enters the heat exchanger 12 from the other end 12b. Inflow. The refrigerant in the gas-liquid two-phase state is converted into low-temperature and low-pressure refrigerant vapor by cooling air or the like with the heat exchanger 12. Thereafter, the refrigerant returns to the compressor 10 through the switching unit 16.

[0057] Cooling main operation mode

When the indoor units 6P and 6Q perform cooling operation and the indoor unit 6R performs heating operation, the switching unit 16 is in the first flow state (the refrigerant discharge port 10a of the compressor 10 is connected to one end 12a of the heat exchanger 12, and the cooling medium suction port). 10b is connected to pipe connection 20a), flow control valves 36 and 68 are closed, flow control valves 32P and 32Q are closed, and flow control valve 32R is fully opened. In addition, the connection port 24b is closed and the connection ports 24a and 24c are opened for the three-way switching valves 22P and 22Q. Three-way selector valve 2 For 2R, close the connecting port 24a and open the connecting ports 24b and 24c. In this state, operation of the compressor 10 is started.

First, the low-temperature and low-pressure refrigerant vapor is compressed by the compressor 10 and discharged as a high-temperature and high-pressure refrigerant. The high-temperature and high-pressure refrigerant discharged from the compressor 10 passes through the switching unit 16 and decreases in temperature while heating air or the like by heat exchange 12. The high-pressure refrigerant that has flowed out of the heat exchange flows into the indoor unit 6R through the check valve 56, the pipe connection 20b, and the three-way switching valve 22R, and heats the air by heat exchange 28 to further lower the temperature. The refrigerant then flows into the indoor units 6P and 6Q, and is expanded (decompressed) by the flow control valves 32P and 32Q to enter a low-temperature and low-pressure gas-liquid two-phase state. This refrigerant further cools the air and the like by heat exchange 28 and changes to low-temperature and low-pressure refrigerant vapor. The refrigerant from the indoor units 6P and 6Q merges after passing through the three-way switching valves 22P and 22Q, and passes through the pipe connection portion 20a. Since the refrigerant in the pipe connection part 20a is at a lower pressure than the refrigerant between the switching part 16 and the check valve 54, it automatically passes through the check valve 54. Therefore, it returns to the compressor 10 through the switching unit 16.

[0059] In the cooling main operation mode of the second embodiment, the flow control valve 36 is closed, and the force described for the operation in which all the refrigerant flows through the indoor unit 6R that performs heating is increased. In order to cause corrosion of the pipe, control the flow control valve 36 and flow the refrigerant so that a part of the refrigerant passes through the first bypass pipe 34 and bypasses the indoor unit 6R.

[0060] Heating main operation mode

When the indoor units 6P and 6Q perform heating operation and the indoor unit 6R performs cooling operation, the switching unit 16 is in the second flow state (the refrigerant discharge port 10a of the compressor 10 is connected to the pipe connection unit 20a, and the refrigerant suction port 10b is heat-exchanged. The flow control valve 36 is closed, the flow control valves 32P and 32Q are fully opened, and the flow control valves 32R and 68 are opened. Further, the connection port 24a is closed and the connection ports 24b and 24c are opened for the three-way switching valves 22P and 22Q. Three-way selector valve 2 For 2R, close connection port 24b and open connection ports 24a and 24c. In this state, operation of the compressor 10 is started.

First, the low-temperature and low-pressure refrigerant vapor is compressed by the compressor 10 and discharged as a high-temperature and high-pressure refrigerant. The high-temperature and high-pressure refrigerant discharged from the compressor 10 passes through the switching unit 16, the check valve 60, and the piping connection unit 20b, then branches and passes through the three-way switching valves 22P and 22Q, and passes through the indoor units 6P and 6Q. It flows into heat exchange 28. The refrigerant heats air or the like by heat exchange 28 and decreases its temperature. The refrigerant that has passed through the heat exchangers 28 of the indoor units 6P and 6Q passes through the fully-open flow control valves 32P and 32Q, and then partially passes through the indoor unit 6R and the rest through the bypass pipe 34.

[0062] The refrigerant that has flowed into the indoor unit 6R is expanded (depressurized) by the flow control valve 32R, and changes to a low-temperature low-pressure gas-liquid two-phase state. Subsequently, the refrigerant cools air or the like in the heat exchanger 28 of the indoor unit 6R, evaporates part or all of it, and flows into the three-way switching valve 22R.

[0063] On the other hand, the remaining refrigerant that has not flowed into the indoor unit 6R also flows into the bypass pipe 66 with the bypass pipe 34 force, and is throttled and expanded (decompressed) by the flow control valve 68 to generate a low-temperature and low-pressure gas-liquid two-phase. It becomes a state. The refrigerant that exits the flow control valve 68 merges with the refrigerant that exits the three-way selector valve 22R (at the end of the bypass pipe 66 connected to the pipe 18a) to become a refrigerant in a gas-liquid two-phase state. Pass through connection end 20a. The refrigerant in the pipe connection part 20a is opposite to the switching part 16. Since the pressure is lower than that of the refrigerant between the check valves 54, the refrigerant automatically passes through the check valve 64 and flows into the heat exchanger 12 from the other end 12 b. The refrigerant in the gas-liquid two-phase state is converted into low-temperature and low-pressure refrigerant vapor by cooling air or the like with the heat exchanger 12. Thereafter, the refrigerant passes through the switching unit 16 and returns to the compressor 10.

[0064] According to the present embodiment, in consideration of the effects of the first embodiment, one of the two inter-unit piping of the relay unit 8A that connects the outdoor unit 4A and the indoor units 6P to 6R. Since only the high-pressure refrigerant flows through 18b and only the low-pressure refrigerant flows through the other pipe 18a, the thickness of the pipe 18a can be reduced.

[0065] In the second embodiment, a pair of (two) two-way switching valves 22, 23 may be provided as shown in FIG. That is, one two-way switching valve 22 has one end connected to the pipe 18a and the second bypass pipe 66, and the other end connected to each of the indoor units 6P to 6R. The other two-way switching valve 23 has one end connected to the pipe 18b and the other end connected to each of the indoor units 6P to 6R. Thus, as in the second embodiment, the direction of the refrigerant flowing through the pipes 18a and 18b (and the two-way switching valves 22 and 23) can always be a constant direction regardless of the operation mode.

[0066] The power described in the specific embodiments of the present invention is not limited to these, and various modifications or changes can be made without departing from the scope and spirit of the present invention. For example, the switching unit provided corresponding to each indoor unit 6P to 6R and selectively connecting the end 28a of the heat exchanger 28 to the pipe 18a or the pipe 18b is a three-way switching valve 22P to 22R or more. You may comprise outside.

[0067] Further, in the second embodiment, the refrigerant flows from the outdoor unit 4A to the relay unit 8A via the pipe connection part 20b regardless of the operation mode, and from the relay part 8A to the outdoor unit via the pipe connection part 20a. The flow path switching unit 52 for allowing the flow to 4A is not limited to the configuration shown in the figure. That is, when the refrigerant discharge port 10a of the compressor 10 is connected to one end 12a of the heat exchanger 12 and the refrigerant suction port 10b is connected to the pipe connection portion 20a as a flow path switching unit ( In the first flow state), the refrigerant flowing out from the other end 12b of the heat exchanger 12 is prohibited from flowing to the pipe connecting part 2 Oa and to the pipe connecting part 20b. Prohibit distribution of refrigerant flowing into 4A to the other end 12b of the heat exchanger 12 And it distribute | circulates to the refrigerant | coolant suction inlet of a compressor. The flow path switching unit is further connected when the switching unit 16 connects the refrigerant discharge port 10a of the compressor 10 to the pipe connection unit 20a and the refrigerant suction port 10b to one end 12a of the heat exchanger (second flow state). ), The refrigerant discharged from the compressor 10 is prohibited from flowing to the pipe connecting part 20a and is distributed to the pipe connecting part 20b, and the refrigerant flowing into the outdoor unit 4A from the pipe connecting part 20a is refrigerant of the compressor. A configuration that prohibits the flow to the discharge port and the flow to the other end 12b of the heat exchanger 12 is included within the scope of the present invention.

[0068] Furthermore, in the above-described embodiment, a simple substance of carbon dioxide and carbon is used as the refrigerant, but a refrigerant mainly containing carbon dioxide may be used.

In the present invention, the “unit” of the indoor unit and the outdoor unit does not necessarily mean that all the components are provided in the same housing or the outer wall of the housing. For example, even if the flow control valve 32 of the indoor unit 4 is disposed at a location different from the housing in which the indoor heat exchanger 28 is accommodated, a configuration that works is included within the scope of the present invention. In addition, multiple sets of outdoor heat exchangers and compressors are provided in the outdoor unit, and the refrigerant flowing out from each set is merged to flow through one inter-unit piping, and the refrigerant from the other inter-unit piping is branched. Then you can let it flow into each set!

Claims

The scope of the claims

[1] An air conditioner,

An outdoor heat exchanger disposed so as to be in fluid communication between the first and second connection ends, compression that compresses and discharges the refrigerant mainly composed of diacid-carbon or diacid-carbon. And an indoor heat exchanger arranged to fluidly communicate between the outdoor unit having a first switching unit that switches the direction of the refrigerant flowing in the outdoor heat exchanger and the first and second pipe connection units And a plurality of indoor units having a first flow rate control unit for controlling the amount of refrigerant flowing through the indoor heat exchanger,

A plurality of second switching sections for selectively connecting each first pipe connection section of the indoor unit to one of the first and second connection end sections of the outdoor unit; Each of the second pipe connection portions of the outdoor unit and the second connection end portion of the outdoor unit, and a relay portion having a second flow rate control portion interposed in the first bypass piping. And an air conditioner.

[2] The air conditioner according to claim 1,

The compressor has a refrigerant suction port and a refrigerant discharge port,

The first switching unit has a first state in which the refrigerant discharge port is connected to one end of the outdoor heat exchanger and the refrigerant suction port is connected to the first connection end according to the operation mode of the air conditioner. An air conditioner that switches between a second state in which the refrigerant discharge port is connected to the first connection end and the refrigerant suction port is connected to the one end of the outdoor heat exchanger.

[3] The air conditioner according to claim 2,

The refrigerant is characterized in that, when the first switching unit is in the first and second states, it heats the outdoor heat exchange and the air in the indoor heat exchange without condensing in the supercritical state, respectively. Air conditioner.

[4] The air conditioner according to claim 1,

When the first switching unit is in the first state, the refrigerant from the outdoor heat exchanger is guided to the second connection end, and the refrigerant from the first connection end is guided to the refrigerant suction port of the compressor. When the first switching unit is in the second state, the refrigerant from the refrigerant discharge port of the compressor is proposed to the second connection end. The flow path switching unit that guides the refrigerant having the first connection end force to the outdoor heat exchanger ^ and the first connection end of the outdoor unit and the first bypass pipe are in fluid communication. A second noisy pipe installed;

An air conditioner further comprising: a third flow rate control unit interposed in the second bypass pipe.

[5] The air conditioner according to claim 4,

The flow path switching unit includes a first check valve interposed in the first flow path between the first connection end and the compressor, and a second connection between the second connection end and the outdoor heat exchanger. A second check valve interposed in the first flow path, a third check valve interposed in the third flow path between the first connection end and the outdoor heat exchanger, and a second connection end And a fourth check valve interposed in a fourth flow path between the compressors.

[6] The air conditioner according to claim 4,

The second switching unit is connected to the first and second connection ends of the outdoor unit via the first and second inter-unit piping, respectively.

An air conditioner characterized in that the first inter-unit piping also has a piping force that is thinner than the second inter-unit piping.

[7] The air conditioner according to claim 1,

Each of the first switching unit and the second switching unit can be operated independently of each other.

[8] The air conditioner according to claim 1,

The air conditioner characterized in that the first switching unit is a four-way switching valve force.

[9] The air conditioner according to claim 1,

Each of the second switching portions is a three-way switching valve force connected to the first and second connection ends of the outdoor unit and the first piping connection portion of the indoor unit. .

[10] The air conditioner according to claim 1,

Each of the second switching units includes a first two-way switching valve connected to the first connection end of the outdoor unit and the first pipe connection of the indoor unit, and a second connection end of the outdoor unit. And an air conditioner comprising: a second two-way switching valve connected to the first pipe connection of the indoor unit.