OUTDOOR UNIT

Abstract

 [Abstract] The present disclosure provides an outdoor unit which eliminates a discharge temperature difference between compressors caused by a layout difference inside the outdoor unit to improve cooling capacity. The distance between a second compressor 111b and an outdoor heat exchanger 114 is smaller than the distance between a first compressor 111a and the outdoor heat exchanger 114, an injection pipe 120 includes a first branch pipe 121a and the second branch pipe 121b which branch at a branch part 123, the first branch pipe 121a is connected to a compression chamber of the first compressor 111a, the second branch pipe 121b is connected to a compression chamber of the second compressor 111b, the branch part 123 is installed above the first compressor 111a and the second compressor 111b, and the height of the second branch pipe 121b is set to be larger than the height of the first branch pipe 121a.

Description

[Technical Field]

[0001] The present disclosure relates to an outdoor unit which injects a part of a refrigerant into, for example, a compression chamber inside a compressor.

[Background Art]

[0002] Patent Literature 1 discloses an air conditioner which injects a part of a refrigerant into, for example, a compression chamber having an intermediate pressure inside a compressor.

[0003] This air conditioner includes a refrigerant circuit which conducts a refrigeration cycle, the refrigerant circuit being formed by annularly connecting a plurality of compressors, a four-way valve, an outdoor heat exchanger, a receiver tank, a subcooling heat exchanger, an indoor expansion valve, and an indoor heat exchanger. The refrigerant circuit also includes a liquid pipe through which a liquid refrigerant which has passed through the outdoor heat exchanger flows in a cooling operation, a first branch pipe through which the branched refrigerant flows from the liquid pipe, and a subcooling expansion valve provided on the first branch pipe. The refrigerant inside the liquid pipe is subcooled by exchanging heat with the branched refrigerant which has passed through the subcooling expansion valve. The heat-exchanged branched refrigerant is injected into the compression chamber provided in the compressor, the compression chamber having an intermediate pressure in the compressor. The air conditioner further includes a controller which controls the openings of both of the subcooling expansion valve and the indoor expansion valve, and a liquid temperature sensor capable of measuring the temperature of the liquid pipe.

[Citation List]

[Patent Literature]

[0004] [Patent Literature 1]
Japanese Patent No. 4479828

[Summary of Invention]

[Technical Problem]

[0005] The present disclosure provides an outdoor unit which eliminates a refrigerant discharge temperature difference between compressors caused by a layout inside the outdoor unit to enable improvement in cooling capacity.

[Solution to Problem]

[0006] This specification includes the entire contents of Japanese Patent Application No. 2021-092379 filed on June 1, 2021.

[0007] An outdoor unit in the present disclosure includes: an outdoor heat exchanger; a first compressor; a second compressor having a smaller distance to the outdoor heat exchanger than the first compressor; a high-pressure refrigerant pipe; an injection pipe branching from the high-pressure refrigerant pipe; and an outdoor fan installed at an upper part of the outdoor heat exchanger, in which the injection pipe includes a first branch pipe and the second branch pipe, the first branch pipe and the second branch pipe branching at a branch part, the first branch pipe is connected to a compression chamber of the first compressor, the second branch pipe is connected to a compression chamber of the second compressor, the branch part is installed above the first compressor and the second compressor, and the second branch pipe is installed at a position higher than the first branch pipe.

[Advantageous Effect of Invention]

[0008] During operation of the outdoor unit in the present disclosure, outside air drawn in by the outdoor fan passes through the outdoor heat exchanger. At this time, the air velocity in the upper part of the outdoor heat exchanger close to the outdoor fan is higher than the air velocity in the lower part far from the outdoor fan. Thus, by installing the second branch pipe higher than the first branch pipe, the second branch pipe exchanges heat with the outside air having a higher air velocity than the outside air with which the first branch pipe exchanges heat. Accordingly, the refrigerant inside the second branch pipe has a larger amount of heat exchange with the outside air than the refrigerant inside the first branch pipe. Thus, in a cooling operation, the refrigerant inside the second branch pipe has a higher ratio of gas refrigerant than the refrigerant inside the first branch pipe, and, conversely, the refrigerant inside the first branch pipe has a higher ratio of liquid refrigerant than the refrigerant inside the second branch pipe. Therefore, a decrease in the refrigerant discharge temperature caused by the injected refrigerant is larger in the first compressor than in the second compressor.

[0009] On the other hand, according to the layout inside the outdoor unit in the present disclosure, the first compressor is installed farther from the outdoor heat exchanger than the second compressor is. Thus, the amount of heat exchange between the first compressor and the outside air is smaller than the amount of heat exchange between the second compressor and the outside air. Therefore, when only the layout of the compressors is taken into consideration, the refrigerant discharge temperature of the first compressor tends to be higher than that of the second compressor.

[0010] As described above, in the present disclosure, the decrease in the refrigerant discharge temperature caused by the refrigerant injected into each of the compressors is larger in the first compressor than in the second compressor. This reduces the difference in the refrigerant discharge temperature caused by the layout of the first compressor and the second compressor and enables an operation with increased cooling capacity with a higher rotation speed of the first compressor having a higher refrigerant discharge temperature.

[Brief Description of Drawings]

[0011] 

[Fig. 1] Fig. 1 is s diagram showing a configuration of a refrigerant circuit including an outdoor unit in a first embodiment.

[Fig. 2] Fig. 2 is a layout front view of the outdoor unit in the first embodiment.

[Fig. 3] Fig. 3 is a layout top view of the outdoor unit in the first embodiment.

[Fig. 4] Fig. 4 is a Mollier chart showing a refrigerant state in an air conditioner.

[Fig. 5] Fig. 5 is a Mollier chart showing a refrigerant state via a first compressor.

[Fig. 6] Fig. 6 is a Mollier chart showing a refrigerant state via a second compressor.

[Fig. 7] Fig. 7 is a layout front view of an outdoor unit in a second embodiment of the present disclosure.

[Fig. 8] Fig. 8 is an air velocity distribution graph inside the outdoor unit in the second embodiment of the present disclosure.

[Description of Embodiment]

(Knowledge and the like Underlying Present Disclosure)

[0012] At the time when the inventors conceived the present disclosure, there was a need for improved energy efficiency in air conditioners. Thus, in the industry concerned, there was a technique to improve the energy efficiency of a compressor in an air conditioner.

[0013] The air conditioner includes a refrigerant circuit which conducts a refrigeration cycle, the refrigerant circuit being formed by annularly connecting a plurality of compressors, a four-way valve, an outdoor heat exchanger, a receiver tank, a subcooling heat exchanger, an indoor expansion valve, and an indoor heat exchanger. The refrigerant circuit also includes a liquid pipe through which a liquid refrigerant which has passed through the outdoor heat exchanger flows in a cooling operation, a first branch pipe through which the branched refrigerant flows from the liquid pipe, and a subcooling expansion valve provided on the first branch pipe. In this air conditioner, the refrigerant inside the liquid pipe is subcooled by exchanging heat with the branched refrigerant which has passed through the subcooling expansion valve. The heat-exchanged branched refrigerant is injected into the compression chamber provided in the compressor, the compression chamber having an intermediate pressure in the compressor. The air conditioner further includes a controller which controls the openings of both of the subcooling expansion valve and the indoor expansion valve, and a liquid temperature sensor capable of measuring the temperature of the liquid pipe. The controller sets a target temperature of the subcooled refrigerant in the liquid pipe according to the cooling load of the indoor heat exchanger and controls the opening of the subcooling expansion valve such that the temperature measured by the liquid temperature sensor becomes the target temperature.

[0014] Accordingly, the amount of the refrigerant injected into the compression chamber changes according to the cooling load, which reduces unnecessary work done by the compressor and increases energy efficiency. While the amount of the branched refrigerant flowing through the subcooling heat exchanger increases in the cooling operation, the amount of the liquid refrigerant flowing through the indoor heat exchanger decreases. However, the decrease in the amount of the liquid refrigerant causes a reduction in the piping resistance, resulting in a smaller reduction in the flow rate of the liquid refrigerant circulating through the indoor heat exchanger, which enables the cooling capacity to be certainly enhanced by controlling the opening of the subcooling expansion valve.

[0015] However, the conventional configuration described above has a problem in that the cooling capacity may not be sufficiently exhibited due to a layout inside the outdoor unit.

[0016] Specifically, when the distance to the outdoor heat exchanger differs between the compressors, the amount of heat exchange with the outdoor air passing through the outdoor heat exchanger differs between the compressors, which results in a difference in refrigerant discharge temperature between the compressors. In particular, in the cooling operation, when each of the compressors operates at a high rotation speed, the compressor farther from the outdoor heat exchanger reaches a reference refrigerant discharge temperature before the compressor closer to the outdoor heat exchanger does. Thus, the rotation speed of the compressor farther from the outdoor heat exchanger is limited, which makes it difficult to improve the cooling capacity.

[0017] Under such circumstances, the inventors have conceived injecting refrigerants having different degrees of dryness into the respective compressors to equalize the refrigerant discharge temperature between the compressors. Further, in order to realize the conception, the inventors have found a problem of a uniform heat exchange amount between the refrigerant and the outside air in each branch pipe for injection, and have come to constitute the subject matter of the present disclosure to solve this problem.

[0018] Thus, the present disclosure provides an outdoor unit which can reduce a difference in refrigerant discharge temperature between compressors caused by a layout by injecting refrigerants having different degrees of dryness into the respective compressors.

[0019] Hereinbelow, embodiments will be described in detail with reference to the drawings. Note that more details than necessary may be omitted. For example, detailed description of already well-known matters or repetitive description for substantially identical configurations may be omitted.

[0020] Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter described in the claims.

(First Embodiment)

[0021] Hereinbelow, a first embodiment will be described.

[1-1. Configuration]

[1-1-1. Configuration of Refrigerant Circuit]

[0022] Fig. 1 is a configuration diagram showing a refrigerant circuit of an air conditioner including an outdoor unit in the first embodiment of the present disclosure.

[0023] An air conditioner 100 of the first embodiment includes an outdoor unit 110, an indoor air-conditioning unit 150, a liquid pipe 140, and a gas pipe 160.

[0024] Note that, although Fig. 1 shows an example in which two indoor air-conditioning units 150 are connected in parallel, one or three or more indoor air-conditioning units 150 may be connected.

[0025] In the present embodiment, the outdoor unit 110 includes an outdoor heat exchanger 114, a first compressor 111a, a second compressor 111b, a four-way valve 112, and an outdoor expansion valve 116. As shown in Fig. 1, the outdoor unit 110 may include a receiver tank 118 on a pipe through which a high-pressure refrigerant flows. Also, in the present embodiment, the liquid pipe 140 branches to an injection pipe 120 inside the outdoor unit 110.

[0026] The outdoor unit 110 of the present embodiment has a configuration in which a plurality of compressors such as the first compressor 111a and the second compressor 111b are installed for one outdoor unit 110.

[0027] The first compressor 111a and the second compressor 111b are mechanical devices which compress a refrigerant. The first compressor 111a sucks the refrigerant from a first suction pipe 115a and compresses the refrigerant, and discharges the compressed refrigerant to a first discharge pipe 117a. Similarly, the second compressor 111b sucks the refrigerant from a second suction pipe 115b and compresses the refrigerant, and discharges the compressed refrigerant to a second discharge pipe 117b.

[0028] Note that a compressor in which a compression process is carried out in a sealed vessel and which includes a port for injection in an intermediate-pressure chamber or a two-stage compressor including a low-pressure compressor and a high-pressure compressor which are housed in a sealed vessel can be used as the first compressor 111a and the second compressor 111b.

[0029] Unlike the configuration in the present embodiment, two or more compressors may be connected in parallel or in series.

[0030] The four-way valve 112 is a valve which switches a refrigerant flow direction between a cooling operation and a heating operation of the air conditioner 100 and connected to a confluence of the first discharge pipe 117a and the second discharge pipe 117b and to a confluence of the first suction pipe 115a and the second suction pipe 115b. An accumulator 119 for gas-liquid separation of the refrigerant is provided at the confluence of the first suction pipe 115a and the second suction pipe 115b.

[0031] The outdoor heat exchanger 114 is a heat exchanger in which outside air around the outdoor heat exchanger 114 and the refrigerant exchange heat. Typically, a fin-and-tube type or microtube type heat exchanger is used as the outdoor heat exchanger 114.

[0032] Also, the first discharge pipe 117a and the second discharge pipe 117b are respectively provided with a first discharge temperature sensor 137a and a second discharge temperature sensor 137b each of which detects the temperature of the refrigerant discharged from the corresponding compressor. Similarly, the first suction pipe 115a and the second suction pipe 115b are respectively provided with a first suction temperature sensor 135a and a second suction temperature sensor 135b each of which detects the temperature of the refrigerant sucked by the corresponding compressor.

[0033] The injection pipe 120 is provided with a subcooling expansion valve 127 which decompresses a branched refrigerant branched from the liquid pipe 140 and a subcooling heat exchanger 125 which performs heat exchange between the branched refrigerant and the refrigerant inside the liquid pipe 140. A double pipe, a plate heat exchanger, or the like can be used as the subcooling heat exchanger 125.

[0034] Further, the injection pipe 120 branches into a first branch pipe 121a and a second branch pipe 121b at a branch part 123. The first branch pipe 121a is connected to a compression chamber of the first compressor 111a, and the second branch pipe 121b is connected to a compression chamber of the second compressor 111b. For example, grooveless pipes can be used as the first branch pipe 121a and the second branch pipe 121b.

[0035] Also, a first branch pipe temperature sensor 131a which detects the temperature of the refrigerant injected into the compression chamber of the first compressor 111a is attached to the first branch pipe 121a. Similarly, a second branch pipe temperature sensor which detects the temperature of the refrigerant injected into the compression chamber of the second compressor 111b is attached to the second branch pipe 121b.

[0036] The liquid pipe 140 which connects the outdoor heat exchanger 114 and the indoor heat exchanger 151 is provided with a liquid temperature sensor 139. The liquid temperature sensor 139 detects the temperature of the refrigerant inside the liquid pipe 140 after heat exchange is performed in the subcooling heat exchanger 125. The liquid pipe 140 corresponds to the high-pressure refrigerant pipe.

[0037] Each of the indoor air-conditioning units 150 includes an indoor heat exchanger 151 which preforms heat exchange between indoor air and the refrigerant. Also, as shown in Fig. 1, each of the indoor air-conditioning units 150 may include an indoor expansion valve 153.

[0038] Each device included in the air conditioner 100 is controlled by a controller (not shown).

[1-1-2. Configuration of Outdoor Unit]

[0039] Hereinbelow, the layout of each device inside the outdoor unit 110 will be described with reference to Figs. 2 and 3. Fig. 2 is a schematic diagram showing the layout inside the outdoor unit 110 viewed from the front in the present embodiment, and Fig. 3 is a schematic diagram showing the layout inside the outdoor unit 110 viewed from the top in the present embodiment.

[0040] As shown in Fig. 2, in the present embodiment, an outdoor fan 101 is provided on the upper face of the outdoor unit 110. The outdoor fan 101 is driven by a fan motor (not shown) and feeds air inside the outdoor unit 110 to the outside, thereby drawing outside air 103 into the outdoor unit 110 through the outdoor heat exchanger 114. This facilitates heat exchange between the outside air 103 and the outdoor heat exchanger 114.

[0041] As shown in Fig. 2, the branch part 123 of the injection pipe 120 is provided at a position higher than both a body of the first compressor 111a and a body of the second compressor 111b. In addition, the first branch pipe 121a and the second branch pipe 121b, which branch from the branch part 123, are installed in such a manner that the height of the second branch pipe 121b is larger than the height of the first branch pipe 121a.

[0042] The height of each of the first branch pipe 121a and the second branch pipe 121b indicates the height of the highest part of the branch pipe. Hereinbelow, the height of the highest part of the branch pipe is merely described as the height of the branch pipe.

[0043] As shown in Fig. 3, in the present embodiment, the outdoor heat exchanger 114 is provided on three of the four side faces of the outdoor unit 110. Of the side faces of the outdoor unit 110, the outside air 103 can be drawn into the outdoor unit 110 through the side faces on which the outdoor heat exchanger 114 is provided. On the other hand, of the side faces of the outdoor unit 110, an operation panel (not shown) and a board (not shown) are provided on the side face on which the outdoor heat exchanger 114 is not provided, and the side face thus blocks the flow of air.

[0044] The top view of the layout inside the outdoor unit 110 of Fig. 3 shows the positional relationship between the first compressor 111a and the second compressor 111b.

[0045] As shown in Fig. 3, the first compressor 111a and the outdoor heat exchanger 114 are separated from each other by a distance Ix in the direction of arrow X (hereinbelow, referred to as the X direction) and separated from each other by a distance Iy in the direction of arrow Y (hereinbelow, referred to as the Y direction). Similarly, the second compressor 111b and the outdoor heat exchanger 114 are separated from each other by a distance IIx in the X direction and separated from each other by a distance IIy in the Y direction.

[0046] The distance between the first compressor 111a and the outdoor heat exchanger 114 is defined as the sum of the distance Ix and the distance Iy, and the distance between the second compressor 111b and the outdoor heat exchanger 114 is defined as the sum of the distance IIx and the distance IIy. In this case, the distance between the first compressor 111a and the outdoor heat exchanger 114 is set to be larger than the distance between the second compressor 111b and the outdoor heat exchanger 114.

[1-2. Operation]

[0047] The operation and action of the outdoor unit 110 configured as described above and the air conditioner 100 including the outdoor unit 110 will be described.

[0048] In the cooling operation of the air conditioner 100, the four-way valve 112 allows a pipe into which the first discharge pipe 117a and the second discharge pipe 117b merge and the outdoor heat exchanger 114 to communicate with each other. Thus, the refrigerant compressed by the first compressor 111a and the second compressor 111b flows into the outdoor heat exchanger 114 as a high-temperature and high-pressure gas refrigerant having a discharge superheat degree higher than a saturation temperature at a discharge pressure.

[0049] The high-temperature and high-pressure gas refrigerant flowing into the outdoor heat exchanger 114 condenses by releasing heat to the surrounding outside air 103 drawn in by the outdoor fan 101, thereby becoming a liquid refrigerant in a high-pressure and subcooled state.

[0050] A part of the liquid refrigerant in a high-pressure and subcooled state passing through the outdoor heat exchanger 114 and flowing through the liquid pipe 140 branches and flows into the injection pipe 120 and is decompressed by the subcooling expansion valve 127. The refrigerant decompressed herein passes through the subcooling heat exchanger 125, thereby exchanging heat with the high-pressure refrigerant inside the liquid pipe 140.

[0051] The refrigerant inside the injection pipe 120 passes through the subcooling heat exchanger 125 and receives heat. This refrigerant branches from the injection pipe 120 at the branch part 123, passes through the first branch pipe 121a and the second branch pipe 121b, and is injected into the compression chamber of the first compressor 111a and the compression chamber of the second compressor 111b.

[0052] When the amount of heat exchange between the refrigerant and the outside air 103 is equal between the first branch pipe 121a and the second branch pipe 121b, the refrigerant injected into each of the compressors is the refrigerant near a saturation line corresponding to point G in the Mollier chart of Fig. 4.

[0053] On the other hand, the low-pressure refrigerant corresponding to point E of Fig. 4 sucked into the first compressor 111a and the second compressor 111b from the first suction pipe 115a and the second suction pipe 115b is pressurized and brought into a state corresponding to point H of Fig. 3.

[0054] Thus, inside the compression chamber of each of the compressors, the injected refrigerant in the state corresponding to point G and the pressurized refrigerant in the state corresponding to point H are mixed to become the refrigerant in a state corresponding to point I of Fig. 4.

[0055] That is, the refrigerant inside the compression chamber having an intermediate pressure in each of the compressors is cooled by the injected refrigerant while being compressed. This makes the refrigerant discharge temperature of each of the first compressor 111a and the second compressor 111b lower than that in a case in which the branched refrigerant is not injected into the compression chamber.

[0056] On the other hand, the high-pressure refrigerant inside the liquid pipe 140 releases heat in the subcooling heat exchanger 125, which increases the degree of subcooling. The high-pressure refrigerant passing through the subcooling heat exchanger 125 flows from the outdoor unit 110 into the indoor air-conditioning unit 150 through the liquid pipe 140. The refrigerant flowing into the indoor air-conditioning unit 150 is decompressed by the indoor expansion valve 153 to become a gas-liquid two-phase refrigerant.

[0057] The liquid refrigerant of the gas-liquid two-phase refrigerant evaporates by taking heat from indoor air in the indoor heat exchanger 151 and is brought into a low-pressure and superheated gas state. The indoor air whose heat is taken at this time lowers the indoor temperature, and the air conditioner 100 thus functions as a cooling apparatus.

[0058] The refrigerant in the superheated gas state returns from the indoor air-conditioning unit 150 to the outdoor unit 110 through the gas pipe 160. The gas refrigerant returned to the outdoor unit 110 passes through the four-way valve 112 and the accumulator 119 and is sucked into the first compressor 111a and the second compressor 111b.

[0059] On the other hand, in the heating operation of the air conditioner 100, the four-way valve 112 allows the pipe into which the first discharge pipe 117a and the second discharge pipe 117b merge and the indoor heat exchanger 151 to communicate with each other through the gas pipe 160.

[0060] Thus, the refrigerant compressed by the first compressor 111a and the second compressor 111b flows into the indoor air-conditioning unit 150 as a high-temperature and high-pressure gas refrigerant having a discharge superheat degree higher than the saturation temperature at the discharge pressure. The gas refrigerant flowing into the indoor air-conditioning unit 150 condenses by releasing heat to indoor air in the indoor heat exchanger 151 to become a liquid refrigerant in a high-pressure and subcooled state. The indoor air receiving the heat at this time increases the indoor temperature, and the air conditioner 100 thus functions as a heating apparatus.

[0061] The high-pressure refrigerant flowing out of the indoor heat exchanger 151 passes through the liquid pipe 140 and flows into the outdoor unit 110. A part of the liquid refrigerant in a high-pressure and subcooled state flowing into the outdoor unit 110 branches off and flows into the injection pipe 120, and is decompressed by the subcooling expansion valve 127.

[0062] The decompressed refrigerant passes through the subcooling heat exchanger 125, thereby exchanging heat with the high-pressure refrigerant inside the liquid pipe 140.

[0063] The refrigerant inside the injection pipe 120 receives heat in the subcooling heat exchanger 125. The refrigerant in this state branches from the injection pipe 120 at the branch part 123, passes through the first branch pipe 121a and the second branch pipe 121b, and is injected into the compression chamber of the first compressor 111a and the compression chamber of the second compressor 111b.

[0064] When the amount of heat exchange between the refrigerant and the outside air 103 is equal between the first branch pipe 121a and the second branch pipe 121b, the refrigerant injected into each of the compressors is the refrigerant near the saturation line corresponding to point G in the Mollier chart of Fig. 4.

[0065] On the other hand, the low-pressure refrigerant corresponding to point E of Fig. 4 sucked into the first compressor 111a and the second compressor 111b from the first suction pipe 115a and the second suction pipe 115b is pressurized and brought into a state corresponding to point H of Fig. 3.

[0066] Thus, inside the compression chamber of each of the compressors, the injected refrigerant in the state corresponding to point G and the pressurized refrigerant in the state corresponding to point H are mixed to become the refrigerant in a state corresponding to point I of Fig. 4.

[0067] That is, the refrigerant inside the compression chamber having an intermediate pressure in each of the compressors is cooled by the injected refrigerant while being compressed. This makes the refrigerant discharge temperature of each of the first compressor 111a and the second compressor 111b lower than that in a case in which the branched refrigerant is not injected into the compression chamber.

[0068] On the other hand, the high-pressure refrigerant inside the liquid pipe 140 releases heat in the subcooling heat exchanger 125, which increases the degree of subcooling. The high-pressure refrigerant passing through the subcooling heat exchanger 125 is decompressed by the outdoor expansion valve 116 to become a gas-liquid two-phase refrigerant.

[0069] The liquid refrigerant of the gas-liquid two-phase refrigerant evaporates by taking heat from the surrounding outside air 103 in the outdoor heat exchanger 114 and is brought into a low-pressure and superheated gas state. This gas refrigerant passes through the four-way valve 112 and the accumulator 119 and is sucked into the first compressor 111a and the second compressor 111b.

[0070] In the cooling operation and the heating operation described above, the outdoor fan 101 is actually rotating in the outdoor unit 110, thereby facilitating heat exchange between the outdoor heat exchanger 114 and the outside air 103.

[0071] The outside air 103 drawn in by the outdoor fan 101 passes through the outdoor heat exchanger 114, and the air velocity of the outside air 103 inside the outdoor unit 110 is higher in an upper part of the outdoor heat exchanger 114, the upper part being close to the outdoor fan 101, and lower in a lower part of the outdoor heat exchanger 114, the lower part being far from the outdoor fan 101.

[0072] In the present embodiment, the second branch pipe 121b is disposed at a position where the second branch pipe 121b comes into contact with outside air having a higher air velocity than outside air that the first branch pipe 121a comes into contact with. Specifically, the height of the second branch pipe 121b is set to be larger than the height of the first branch pipe 121a, so that the refrigerant inside the second branch pipe 121b exchanges heat with more outside air than the refrigerant inside the first branch pipe 121a. Therefore, the refrigerant inside the second branch pipe 121b receives more heat and thus has a higher ratio of gas components than the refrigerant inside the first branch pipe 121a. Conversely, the refrigerant inside the first branch pipe 121a receives less heat and thus has a higher ratio of liquid components than the refrigerant in the second branch pipe 121b.

[0073] Fig. 4 shows the Mollier chart in a case in which the amount of heat exchange between the refrigerant and the outside air 103 is equal between the first branch pipe 121a and the second branch pipe 121b. This corresponds to a case in which the height of the first branch pipe 121a is equal to the height of the second branch pipe 121b.

[0074] However, in practice, when the layout inside the outdoor unit 110 of the present embodiment is taken into consideration, the amount of heat exchange between the refrigerant and the outside air differs between the first branch pipe 121a and the second branch pipe 121b.

[0075] Fig. 5 shows the Mollier chart of the refrigerant passing through the first compressor 111a during operation of the air conditioner 100 in a case in which the first branch pipe 121a is installed with its height smaller than that in the case of Fig. 4, reflecting the layout inside the outdoor unit 110.

[0076] Since the first branch pipe 121a is installed with its height smaller than that in the case of Fig. 4, the refrigerant passing through the first branch pipe 121a to be injected into the first compressor 111a exchanges heat with the outside air 103 having a low air velocity and thus has a small amount of heat exchange with the outside air 103. Thus, the refrigerant which has passed through the first branch pipe 121a has a lower degree of dryness than in the case of Fig. 4 and is brought into a state corresponding to point Ga of Fig. 5.

[0077] Thus, the refrigerant in a state corresponding to point Ia of Fig. 5 which is a mixture of the refrigerant in a state corresponding to point H and the refrigerant in the state corresponding to point Ga during compression in the compression chamber of the first compressor 111a has a lower temperature than the refrigerant in the state corresponding to point I of Fig. 4. Accordingly, the refrigerant discharged from the first compressor 111a is brought into a state corresponding to point Aa and has a lower temperature than the refrigerant in a state corresponding to point A.

[0078] Fig. 6 shows the Mollier chart of the refrigerant passing through the second compressor 111b during operation of the air conditioner 100 in a case in which the second branch pipe 121b is installed with its height larger than that in the case of Fig. 4.

[0079] Since the second branch pipe 121b is installed with its height larger than that in the case of Fig. 4, the refrigerant passing through the second branch pipe 121b to be injected into the second compressor 111b exchanges heat with the outside air 103 having a high air velocity and thus has a large amount of heat exchange with the outside air 103. Thus, the refrigerant which has passed through the second branch pipe 121b has a higher degree of dryness than in the case of Fig. 4 and is brought into a state corresponding to point Gb of Fig. 6.

[0080] Thus, the refrigerant in a state corresponding to point Ib of Fig. 6 which is a mixture of the refrigerant in a state corresponding to point H and the refrigerant in the state corresponding to point Gb during compression in the compression chamber of the second compressor 111b has a higher temperature than the refrigerant in the state corresponding to point I of Fig. 4. Accordingly, the refrigerant discharged from the second compressor 111b is brought into a state corresponding to point Ab and has a higher temperature than the refrigerant in the state corresponding to point A.

[0081] When the branch part 123 is installed below the upper ends of the first compressor 111a and the second compressor 111b, the height of the first branch pipe 121a and the second branch pipe 121b through which the refrigerant passes after the branch part 123 is substantially equal to the height of the first compressor 111a and the second compressor 111b. Thus, the outside air 103 drawn in by the outdoor fan 101 passes through the outdoor heat exchanger 114 and comes into contact with the first compressor 111a, the second compressor 111b, and other structures, which results in nonuniform air velocity and temperature of the outside air 103 around the first compressor 111a and the second compressor 111b. As a result, the temperature of the refrigerant discharged by the first compressor 111a and the second compressor 111b into the first discharge pipe 117a and the second discharge pipe 117b becomes nonuniform.

[0082] However, in the present embodiment, the branch part 123 is installed above the upper ends of the first compressor 111a and the second compressor 111b. Accordingly, the height of the first branch pipe 121a and the second branch pipe 121b through which the refrigerant passes after the branch part 123 is larger than the height of the first compressor 111a and the second compressor 111b. Thus, the outside air 103 drawn in by the outdoor fan 101 passes through the outdoor heat exchanger 114 and does not come into contact with the first compressor 111a, the second compressor 111b, and other structures, which does not result in nonuniform air velocity and temperature of the outside air 103 around the first compressor 111a and the second compressor 111b. As a result, the discharge temperature of the refrigerant discharged by the first compressor 111a and the second compressor 111b into the first discharge pipe 117a and the second discharge pipe 117b becomes uniform.

[0083] Also, in the present disclosure, the amount of heat exchange between the first branch pipe 121a and the second branch pipe 121b, and the outside air 103 differs depending on an operation mode of the air conditioner 100.

[0084] The difference in the amount of heat exchange between the operation modes when an R32 refrigerant is used as the refrigerant of the air conditioner 100 will be described below as an example.

[0085] The refrigerant in a low-pressure part when the air-conditioner 100 performs a cooling operation under an outside air temperature of 35°C so that the blow-off temperature from the indoor air-conditioning unit 150 becomes 15°C has a temperature of 10°C, which is 5 K lower than the blow-off temperature from the indoor air-conditioning unit 150, and a pressure of 1.1 Mpa. In addition, the refrigerant to be injected has a pressure of 1.5 MPa, which is 1.4 times the pressure of the low-pressure part, and a temperature of 21°C. In this case, the difference between the temperature of the refrigerant flowing through the first branch pipe 121a and the second branch pipe 121b and the outside air temperature is approximately 14 K.

[0086] On the other hand, the refrigerant in the low-pressure part when the air-conditioner 100 performs a heating operation under an outside air temperature of 7°C has a temperature of approximately -0.5°C, which is the temperature at which frost forms on an evaporator, and a pressure of 0.8 Mpa. In addition, the refrigerant to be injected has a pressure of 1.1 MPa, which is 1.4 times the pressure of the low-pressure part, and a temperature of 10°C. In this case, the difference between the temperature of the refrigerant flowing through the first branch pipe 121a and the second branch pipe 121b and the outside air temperature is approximately 3 K.

[0087] Thus, the difference between the outside air temperature and the temperature of the refrigerant flowing through the first branch pipe 121a and the second branch pipe 121b is larger in the cooling operation than in the heating operation.

[0088] Therefore, the amount of heat exchange performed between the outside air 103 and the refrigerant flowing through the first branch pipe 121a and the second branch pipe 121b is larger in the cooling operation than in the heating operation in the air conditioner 100.

[1-3. Effects and the like]

[0089] In the present embodiment, the outdoor unit 110 includes the first compressor 111a, the second compressor 111b, the outdoor heat exchanger 114, the liquid pipe 140, the injection pipe 120 which branches from the liquid pipe 140, and the outdoor fan 101 which is installed at the upper part of the outdoor heat exchanger 114. The distance between the second compressor 111b and the outdoor heat exchanger 114 is smaller than the distance between the first compressor 111a and the outdoor heat exchanger 114. The injection pipe 120 includes the first branch pipe 121a and the second branch pipe 121b which branch at the branch part 123, the first branch pipe 121a is connected to the compression chamber of the first compressor 111a, and the second branch pipe 121b is connected to the compression chamber of the second compressor 111b. Further, the branch part 123 is installed above the first compressor 111a and the second compressor 111b, and the height of the second branch pipe 121b is set to be larger than the height of the first branch pipe 121a.

[0090] According to this, the outside air 103 drawn in by the outdoor fan 101 passes through the outdoor heat exchanger 114, and the air velocity of the outside air 103 inside the outdoor unit 110 is higher in the upper part of the outdoor heat exchanger 114 close to the outdoor fan 101 and lower in the lower part far from the outdoor fan 101.

[0091] Thus, since the height of the second branch pipe 121b is set to be larger than the height of the first branch pipe 121a, the refrigerant inside the second branch pipe 121b exchanges heat with more outside air than the refrigerant inside the first branch pipe 121a. Therefore, the refrigerant inside the second branch pipe 121b receives more heat and thus has a higher ratio of gas components than the refrigerant inside the first branch pipe 121a.

[0092] That is, since the first branch pipe 121a is installed with its height smaller than that in the case of Fig. 4, the refrigerant passing through the first branch pipe 121a exchanges heat with the outside air 103 having a low air velocity and thus has a small amount of heat exchange with the outside air 103. Thus, the refrigerant which has passed through the first branch pipe 121a has a lower degree of dryness than in the case of Fig. 4, and is brought into the state corresponding to point Ga of Fig. 5 and injected into the first compressor 111a.

[0093] Thus, the refrigerant in the state corresponding to point Ia of Fig. 5 which is the mixture of the refrigerant in the state corresponding to point H and the refrigerant in the state corresponding to point Ga during compression in the compression chamber of the first compressor 111a has a lower temperature than the refrigerant in the state corresponding to point I of Fig. 4. Accordingly, the refrigerant discharged from the first compressor 111a is brought into the state corresponding to point Aa and has a lower temperature than the refrigerant in the state corresponding to point A.

[0094] Further, since the second branch pipe 121b is installed with its height larger than that in the case of Fig. 4, the refrigerant passing through the second branch pipe 121b exchanges heat with the outside air 103 having a high air velocity and thus has a large amount of heat exchange with the outside air 103. Thus, the refrigerant which has passed through the second branch pipe 121b has a higher degree of dryness than in the case of Fig. 4, and is brought into the state corresponding to point Gb of Fig. 6 and injected into the second compressor 111b.

[0095] Thus, the refrigerant in the state corresponding to point Ib of Fig. 6 which is the mixture of the refrigerant in the state corresponding to point H and the refrigerant in the state corresponding to point Gb during compression in the compression chamber of the second compressor 111b has a higher temperature than the refrigerant in the state corresponding to point I of Fig. 4. Accordingly, the refrigerant discharged from the second compressor 111b is brought into the state corresponding to point Ab and has a higher temperature than the refrigerant in the state corresponding to point A.

[0096] Therefore, a decrease in the refrigerant discharge temperature in each of the compressors caused by the injection of the refrigerant from the corresponding branch pipe can be made larger in the first compressor 111a and smaller in the second compressor 111b.

[0097] This makes it possible to operate the first compressor 111a, which is far from the outdoor heat exchanger 114 and tends to have a high refrigerant discharge temperature, at a high rotation speed as with the second compressor 111b. Thus, the cooling capacity can be improved.

(Second Embodiment)

[0098] Hereinbelow, a second embodiment will be described.

[2-1. Configuration]

[2-1-1. Configuration of Refrigerant Circuit]

[0099] A configuration of a refrigerant circuit of an air conditioner 100 including an outdoor unit 110 of the second embodiment is as shown in Fig. 1 as with the first embodiment. Thus, description of the configuration of the refrigerant circuit will be omitted, and only a layout inside the outdoor unit 110 will be described below.

[2-1-2. Layout inside Outdoor Unit]

[0100] Hereinbelow, the layout inside the outdoor unit 110 in the second embodiment will be described.

[0101] Fig. 7 is a schematic diagram showing the layout of the outdoor unit 110 of the second embodiment viewed from the front. As shown in Fig. 7, in the outdoor unit 110 according to the second embodiment, the height of a second branch pipe 121b connected to a second compressor 111b is set to be larger than both the height of a second discharge pipe 117b and the height of a second suction pipe 115b. On the other hand, the height of a first branch pipe 121a connected to a first compressor 111a is set to be smaller than both the height of a first discharge pipe 117a and the height of a first suction pipe 115a.

[0102] Also, a receiver tank 118 has a shape extending in the height direction so as to reduce the bottom area of the outdoor unit 110.

[2-2. Operation]

[0103] The operation and action of the air conditioner 100 including the outdoor unit 110 configured as described above will be described below. The operation dependent on the configuration of the refrigerant circuit is similar to that in the first embodiment and is thus omitted.

[0104] The receiver tank 118 inside the outdoor unit 110 stores a high-pressure liquid refrigerant in a subcooled state inside the receiver tank 118 and adjusts the pressure in the refrigerant circuit to eliminate the disparity in the amount of refrigerant required between the cooling operation and the heating operation and the disparity in the amount of excess refrigerant depending on the intensity of cooling and heating operations.

[0105] As described in the first embodiment, during operation of the air conditioner 100, the outside air 103 drawn in by the outdoor fan 101 passes through the outdoor heat exchanger 114. Also, the air velocity of the outside air 103 is higher in the upper part of the outdoor heat exchanger 114 close to the outdoor fan 101 and lower in the lower part far from the outdoor fan 101.

[0106] Further, as described in the first embodiment, the flow of the outside air 103 flowing into the outdoor unit 110 is blocked by the structures including the first compressor 111a and the second compressor 111b.

[0107] In the second embodiment, since the height of the second branch pipe 121b is larger than both the height of the second discharge pipe 117b and the height of the second suction pipe 115b, there is no pipe which becomes an obstacle between the second branch pipe 121b and the outside air 103. Thus, as compared to the case in which the height of the second branch pipe 121b is not larger than both the height of the second discharge pipe 117b and the height of the second suction pipe 115b, the amount of heat exchange between the refrigerant inside the second branch pipe 121b and the outside air 103 further increases. This further increases gas components of the refrigerant injected into the second compressor 111b from the second branch pipe 121b.

[0108] On the other hand, the height of the first branch pipe 121a is smaller than both the height of the first discharge pipe 117a and the height of the first suction pipe 115a. Thus, as compared to the case in which the height of the first branch pipe 121a is not smaller than both the height of the first discharge pipe 117a and the height of the first suction pipe 115a, the amount of heat exchange between the refrigerant inside the first branch pipe 121a and the outside air 103 decreases. This further increases liquid components of the refrigerant injected into the first compressor 111a from the first branch pipe 121a.

[0109] That is, since the height of the second branch pipe 121b is larger than both the height of the second discharge pipe 117b and the height of the second suction pipe 115b, the refrigerant at an exit part of the second branch pipe 121b is brought into a state having a higher degree of dryness than that at point Gb of Fig. 6 in the first embodiment. This refrigerant is injected into the second compressor 111b and mixed with the refrigerant which is pressurized inside the second compressor 111b and in the state corresponding to point H of Fig. 6 to become the refrigerant having a higher degree of dryness than the state corresponding to point Ib. This refrigerant has a higher temperature than the refrigerant in the state corresponding to point Ib of Fig. 6. Thus, the temperature of the refrigerant discharged by the second compressor 111b into the second discharge pipe 117b further increases.

[0110] In addition, since the height of the first branch pipe 121a is smaller than both the height of the first discharge pipe 117a and the height of the first suction pipe 115a, the refrigerant at an exit part of the first branch pipe 121a is brought into a state having a lower degree of dryness than that at point Ga of Fig. 5 in the first embodiment. This refrigerant is injected into the first compressor 111a and mixed with the refrigerant which is pressurized inside the first compressor 111a and in the state corresponding to point H of Fig. 5 to become the refrigerant having a lower degree of dryness than the state corresponding to point Ia of Fig. 5. This refrigerant has a lower temperature than the refrigerant in the state corresponding to point Ia of Fig. 5. Thus, the temperature of the refrigerant discharged by the first compressor 111a into the first discharge pipe 117a further decreases.

[0111] Fig. 8 is a graph with the vertical axis representing an air velocity measurement height relative to a product height of the outdoor unit 110 and the horizontal axis representing the air velocity of the outside air 103 drawn into the outdoor unit 110.

[0112] In Fig. 8, while the air velocity of the outside air 103 is almost uniform at the air velocity measurement height less than around 1/2 of the product height of the outdoor unit 110, the air velocity of the outside air 103 increases at higher positions above around 1/2 of the product height of the outdoor unit 110.

[0113] That is, by setting the height of the second branch pipe 121b at around 1/2 of the product height of the outdoor unit 110 or more, the air volume of the outside air 103 increases as the height increases. Thus, the refrigerant inside the second branch pipe 121b can exchange heat with the outside air 103 having a high air velocity, which increases gas components. Thus, when the second branch pipe 121b is installed at the position higher than the second discharge pipe 117b and the second suction pipe 115b, the refrigerant injected into the second compressor 111b from the second branch pipe 121b is within the gas phase region. Therefore, the temperature of the refrigerant mixed with the refrigerant pressurized inside the second compressor 111b increases, which results in an increase in the temperature of the refrigerant discharged to the second discharge pipe 117b of the second compressor 111b.

[2-3. Effects and the like]

[0114] As described above, in the present embodiment, the first compressor 111a inside the outdoor unit 110 includes the first discharge pipe 117a and the first suction pipe 115a. Further, the second compressor 111b includes the second discharge pipe 117a and the second suction pipe 115b. In addition, the second branch pipe 121b of the second compressor 111b is installed at the position higher than both the second discharge pipe 117b and the second suction pipe 115b.

[0115] According to this, since the height of the second branch pipe 121b is larger than both the height of the second discharge pipe 117b and the height of the second suction pipe 115b, there is no pipe which becomes an obstacle between the second branch pipe 121b and the outside air 103. Thus, as compared to the case in which the height of the second branch pipe 121b is not larger than both the height of the second discharge pipe 117b and the height of the second suction pipe 115b, the amount of heat exchange between the refrigerant inside the second branch pipe 121b and the outside air 103 further increases. This further increases gas components of the refrigerant injected into the second compressor 111b from the second branch pipe 121b.

[0116] On the other hand, the height of the first branch pipe 121a is smaller than both the height of the first discharge pipe 117a and the height of the first suction pipe 115a. Thus, as compared to the case in which the height of the first branch pipe 121a is not smaller than both the height of the first discharge pipe 117a and the height of the first suction pipe 115a, the amount of heat exchange between the refrigerant inside the first branch pipe 121a and the outside air 103 decreases. This further increases liquid components of the refrigerant injected into the first compressor 111a from the first branch pipe 121a.

[0117] That is, since the height of the second branch pipe 121b is larger than both the height of the second discharge pipe 117b and the height of the second suction pipe 115b, the refrigerant at the exit part of the second branch pipe 121b is brought into the state having a higher degree of dryness than that at point Gb of Fig. 6 in the first embodiment. This refrigerant is injected into the second compressor 111b and mixed with the refrigerant which is pressurized inside the second compressor 111b and in the state corresponding to point H of Fig. 6 to become the refrigerant having a higher degree of dryness than the state corresponding to point Ib. This refrigerant has a higher temperature than the refrigerant in the state corresponding to point Ib of Fig. 6. Thus, the temperature of the refrigerant discharged by the second compressor 111b into the second discharge pipe 117b further increases.

[0118] In addition, since the height of the first branch pipe 121a is smaller than both the height of the first discharge pipe 117a and the height of the first suction pipe 115a, the refrigerant at the exit part of the first branch pipe 121a is brought into the state having a lower degree of dryness than that at point Ga of Fig. 5 in the first embodiment. This refrigerant is injected into the first compressor 111a and mixed with the refrigerant which is pressurized inside the first compressor 111a and in the state corresponding to point H of Fig. 5 to become the refrigerant having a lower degree of dryness than the state corresponding to point Ia of Fig. 5. This refrigerant has a lower temperature than the refrigerant in the state corresponding to point Ia of Fig. 5. Thus, the temperature of the refrigerant discharged by the first compressor 111a into the first discharge pipe 117a decreases.

[0119] Thus, the decrease in the refrigerant discharge temperature in the second compressor 111b caused by the injection of the refrigerant from the second branch pipe 121b can be further reduced.

[0120] Therefore, in particular, in the case of the outdoor unit 110 having a complicated layout, the temperature difference between the refrigerant discharge temperature of the second compressor 111b and the refrigerant discharge temperature of the first compressor 111a, which tends to be higher due to the layout, can be further reduced.

[0121] Also, as with the present embodiment, the height of the first branch pipe 121a may be smaller than both the height of the first suction pipe 115a and the height of the first discharge pipe.

[0122] This further increases liquid components of the refrigerant injected into the first compressor 111a from the first branch pipe 121a.

[0123] Thus, the decrease in the refrigerant discharge temperature in the first compressor 111a caused by the injection of the refrigerant from the first branch pipe 121a can be further increased.

[0124] Therefore, the refrigerant discharge temperature of the first compressor 111a, which tends to have a high refrigerant discharge temperature, can be further reduced. As a result, the first compressor 111a can be operated at a high rotation speed, and the cooling capacity can thus be improved.

(Other Embodiments)

[0125] As described above, the first and second embodiments have been described as examples of the techniques disclosed in the present application. However, the techniques in the present disclosure are not limited thereto and also applicable to embodiments with changes, replacements, additions, omissions, and the like. Also, the constituent elements described above in the first and second embodiments may be combined to constitute a new embodiment.

[0126] Thus, hereinbelow, other embodiments will be described as examples.

[0127] In the first and second embodiments, the grooveless pipe has been described as an example of the first branch pipe 121a and the second branch pipe 121b. However, in the present disclosure, the discharge temperature difference between the compressors is reduced by changing the amount of heat exchange between the refrigerant and the outside air 103 in the first branch pipe 121a and the second branch pipe 121b according to the arrangement of the branch pipes. Thus, the first branch pipe 121a and the second branch pipe 121b may be any pipes which produce a difference in heat exchange by their arrangement. Therefore, the first branch pipe 121a and the second branch pipe 121b are not limited to the grooveless pipes. However, the use of the grooveless pipes as the first branch pipe 121a and the second branch pipe 121b can reduce manufacturing cost.

[0128] Also, the material of each of the branch pipes may be changed, or a grooved pipe or a fin-and-tube pipe may be used as the branch pipe. For example, a grooveless pipe made of a material having a high heat-insulting property may be used as the first branch pipe 121a, and a grooved pipe or a fin-and-tube pipe may be used as the second branch pipe 121b. In this case, the difference in the heat exchange amount between the branch pipes further increases, which can increase the difference in the temperature decrease caused by the injected refrigerant and further equalize the discharge temperature between the compressors.

[0129] In the first and second embodiments, providing the difference between the amount of heat exchange between the first branch pipe 121a and the outside air 103 and the amount of heat exchange between the second branch pipe 121b and the outside air 103 has been described as an example of means for changing the refrigerant discharge temperature of each of the compressors. The means for changing the refrigerant discharge temperature of each of the compressors may be any means which can change the enthalpy when the refrigerant compressed in each of the compressors flows into to the compressor. Thus, the means for changing the refrigerant discharge temperature of each of the compressors is not limited to changing the height of the first branch pipe 121a and the height of the second branch pipe 121b.

[0130] Also, as the means for changing the refrigerant discharge temperature of each of the compressors, the second suction pipe 115b may be installed higher than the first suction pipe 115a so as to increase liquid components in the first suction pipe 115a of the first compressor 111a and increase gas components in the second suction pipe 115b of the second compressor 111b.

[0131] Also, the arrangement of the first branch pipe 121a and the second branch pipe 121b in the horizontal direction may be changed. In this case, the refrigerant discharge temperature of the first compressor 111a can be reduced by disposing the first branch pipe 121a away from the outdoor heat exchanger 114 or disposing the first branch pipe 121a in an area where the flow of the outside air 103 is blocked by the structures so as to reduce the amount of heat exchange with the outside air 103. Conversely, the refrigerant discharge temperature of the second compressor 111b can be increased by disposing the second branch pipe 121b close to the outdoor heat exchanger 114 or disposing the second branch pipe 121b in an area where the flow of the outside air 103 is not blocked by the structures so as to increase the amount of heat exchange with the outside air 103.

[0132] Thus, for example, the first branch pipe 121a and the second branch pipe 121b may be installed in such a manner that the distance between the second branch pipe 121b and the outdoor heat exchanger 114 is smaller than the distance between the first branch pipe 121a and the outdoor heat exchanger 114.

[0133] In the first and second embodiments, the outdoor fan 101 is installed at the upper part of the outdoor heat exchanger 114. The installation position of the outdoor fan 101 may be any position which enables the outdoor fan 101 to facilitate heat exchange in the outdoor heat exchanger 114. Thus, the installation position of the outdoor fan 101 is not limited to the upper part.

[0134] Thus, the outdoor fan 101 may be installed parallel to the outdoor heat exchanger 114. In this case, the refrigerant discharge temperature can be equalized between the compressors by disposing the second branch pipe 121b in a place where the volume of air is large and disposing the first branch pipe 121a in a place where the volume of air is small. In this case, an air volume distribution of the outside air 103 inside the outdoor unit 110 differs from that in the case in which the outdoor fan 101 is disposed in the upper part, and the layout of each of the branch pipes thus also differs from that in the case in which the outdoor fan 101 is disposed in the upper part.

[0135] Note that, since the embodiments described above are intended to exemplify the techniques in the present disclosure, various changes, replacements, additions, omissions, and the like can be made within the scope of the claims or a scope equivalent thereto.

[Industrial Applicability]

[0136] The present disclosure can be suitably used as an outdoor unit which can eliminate a discharge temperature difference between compressors caused by a layout difference.

[Reference Signs List]

[0137] 

100

air conditioner

101

outdoor fan

103

outside air

110

outdoor unit

111a

first compressor

111b

second compressor

112

four-way valve

114

outdoor heat exchanger

115a

first suction pipe

115b

second suction pipe

116

outdoor expansion valve

117a

first discharge pipe

117b

second discharge pipe

118

receiver tank

119

accumulator

120

injection pipe

121a

first branch pipe

121b

second branch pipe

123

branch part

125

cooling heat exchanger

127

cooling expansion valve

131a

first branch pipe temperature sensor

135a

first suction temperature sensor

135b

second suction temperature sensor

137a

first discharge temperature sensor

137b

second discharge temperature sensor

139

liquid temperature sensor

140

liquid pipe

150

indoor air-conditioning unit

151

indoor heat exchanger

153

indoor expansion valve

160

gas pipe

Claims

1. An outdoor unit characterized by comprising:

an outdoor heat exchanger;

a first compressor;

a second compressor having a smaller distance to the outdoor heat exchanger than the first compressor;

a high-pressure refrigerant pipe;

an injection pipe branching from the high-pressure refrigerant pipe; and

an outdoor fan installed at an upper part of the outdoor heat exchanger, wherein

the injection pipe includes a first branch pipe and a second branch pipe, the first branch pipe and the second branch pipe branching at a branch part,

the first branch pipe is connected to a compression chamber of the first compressor,

the second branch pipe is connected to a compression chamber of the second compressor,

the branch part is installed above the first compressor and the second compressor, and

the second branch pipe is installed at a position higher than the first branch pipe.

2. The outdoor unit according to claim 1, wherein

the first compressor includes a first discharge pipe and a first suction pipe,

the second compressor includes a second discharge pipe and a second suction pipe, and

the second branch pipe is installed at a position higher than both the second discharge pipe and the second suction pipe.

3. An outdoor unit characterized by comprising:

an outdoor heat exchanger;

a first compressor;

a second compressor having a smaller distance to the outdoor heat exchanger than the first compressor;

a high-pressure refrigerant pipe;

an injection pipe branching from the high-pressure refrigerant pipe; and

an outdoor fan installed at an upper part of the outdoor heat exchanger, wherein

the injection pipe includes a first branch pipe and a second branch pipe, the first branch pipe and the second branch pipe branching at a branch part,

the first branch pipe is connected to a compression chamber of the first compressor,

the second branch pipe is connected to a compression chamber of the second compressor, and

the first branch pipe and the second branch pipe are installed in such a manner that a distance between the second branch pipe and the outdoor heat exchanger is smaller than a distance between the first branch pipe and the outdoor heat exchanger.

Drawing