outdoor unit

Abstract

To provide an outdoor unit which eliminates a discharge temperature difference of each compressor due to a layout difference in the outdoor unit and which has cooling performance improved.SOLUTION: A distance between a second compressor 111b and an outdoor heat exchanger 114 is formed to be smaller than a distance between a first compressor 111a and the outdoor heat exchanger 114. An injection pipeline 120 includes a first branch pipe 121a and a second branch pipe 121b branched 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 installed to be larger than the height of the first branch pipe 121a.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an outdoor unit that injects a portion of a refrigerant into a compression chamber or the like in a compressor. [Background technology]

[0002] Patent Document 1 discloses an air conditioner in which a portion of the refrigerant is injected into a compression chamber or the like that is at an intermediate pressure within the compressor. This air conditioner includes a refrigerant circuit that performs a refrigeration cycle and is circularly connected to multiple 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 liquid refrigerant that has passed through the outdoor heat exchanger flows during cooling operation, a first branch pipe that branches off from the liquid pipe, and a subcooling expansion valve installed on the first branch pipe. The refrigerant in the liquid pipe is subcooled by heat exchange with the branched refrigerant that has passed through the subcooling expansion valve. The branched refrigerant after heat exchange is injected into a compression chamber installed in the compressor that is at an intermediate pressure in the compressor. The air conditioner also includes a controller that controls the opening of both the subcooling expansion valve and the indoor expansion valve, and a liquid temperature sensor that can measure the temperature of the liquid pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4479828 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides an outdoor unit that can improve cooling capacity by eliminating differences in refrigerant discharge temperature between compressors due to the layout inside the outdoor unit. [Means for solving the problem]

[0005] The outdoor unit of the present disclosure includes an outdoor heat exchanger, a first compressor, a second compressor that is closer to the outdoor heat exchanger than the first compressor, a high-pressure refrigerant pipe, an injection pipe branched from the high-pressure refrigerant pipe, and an outdoor fan installed above the outdoor heat exchanger, wherein the injection pipe has a first branch pipe and a second branch pipe branched at a branching portion, the first branch pipe is connected to a compression chamber of the first compressor, and the second branch pipe is connected to a compression chamber of the second compressor, the branching portion is installed above the first compressor and the second compressor, and the second branch pipe is installed at a higher position than the first branch pipe. [Effects of the Invention]

[0006] During operation of the outdoor unit of the present disclosure, outdoor air drawn in by the outdoor fan passes through the outdoor heat exchanger. At this time, the air velocity above the outdoor heat exchanger, closer to the outdoor fan, is higher than the air velocity below, further from the outdoor fan. Therefore, by installing the second branch pipe higher than the first branch pipe, the second branch pipe exchanges heat with outdoor air, which has a higher air velocity, than the first branch pipe. As a result, the refrigerant in the second branch pipe exchanges more heat with outdoor air than the refrigerant in the first branch pipe. Therefore, during cooling operation, the refrigerant in the second branch pipe contains a higher proportion of gas refrigerant than the refrigerant in the first branch pipe, and conversely, the refrigerant in the first branch pipe contains a higher proportion of liquid refrigerant than the refrigerant in the second branch pipe. Therefore, the refrigerant discharge temperature is lowered by the injected refrigerant more in the first compressor than in the second compressor. On the other hand, according to the layout of the outdoor unit of the present disclosure, the first compressor is installed farther from the outdoor heat exchanger than the second compressor. Therefore, the amount of heat exchanged between the first compressor and the outdoor air is smaller than the amount of heat exchanged between the second compressor and the outdoor air. Therefore, when only the compressor layout is considered, the refrigerant discharge temperature of the first compressor is likely to be higher than that of the second compressor. As described above, in this disclosure, the amount of decrease in refrigerant discharge temperature due to the refrigerant injected into each compressor is greater in the first compressor than in the second compressor. This reduces the difference in refrigerant discharge temperature caused by the layout of the first and second compressors, and enables operation with higher cooling capacity by increasing the rotation speed of the first compressor, which has a higher refrigerant discharge temperature. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing a configuration of a refrigerant circuit including an outdoor unit according to a first embodiment. [Figure 2] Layout front view of the outdoor unit in the first embodiment [Figure 3] Layout top view of the outdoor unit in the first embodiment [Figure 4] Mollier diagram showing the refrigerant state in an air conditioner [Figure 5] Mollier diagram showing the state of the refrigerant passing through the first compressor [Figure 6] Mollier diagram showing the state of the refrigerant passing through the second compressor [Figure 7] 10 is a front view of the layout of an outdoor unit according to a second embodiment of the present disclosure. [Figure 8] Graph of wind speed distribution inside the outdoor unit according to the second embodiment of the present disclosure DETAILED DESCRIPTION OF THE INVENTION

[0008] (Findings that formed the basis of this disclosure) At the time the inventors arrived at the idea of ​​the present disclosure, there was a demand for improved energy efficiency in air conditioners, and therefore, there was technology in the industry for improving the energy efficiency of compressors in air conditioners.

[0009] The air conditioner includes a refrigerant circuit that performs a refrigeration cycle and is circularly connected to multiple 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 liquid refrigerant that has passed through the outdoor heat exchanger flows during cooling operation, a first branch pipe branching from the liquid pipe, and a subcooling expansion valve installed on the first branch pipe. In this air conditioner, the refrigerant in the liquid pipe is subcooled by heat exchange with the branched refrigerant that has passed through the subcooling expansion valve. After heat exchange, the branched refrigerant is injected into a compression chamber installed in the compressor that is at an intermediate pressure. The air conditioner also includes a controller that controls the apertures of both the subcooling expansion valve and the indoor expansion valve, and a liquid temperature sensor that measures the temperature in the liquid pipe. The controller sets a target temperature for the subcooled refrigerant in the liquid pipe according to the cooling load of the indoor heat exchanger, and controls the aperture of the subcooling expansion valve so that the temperature measured by the liquid temperature sensor reaches the target temperature. This allows the amount of refrigerant injected into the compression chamber to vary depending on the cooling load, reducing wasted work by the compressor and improving energy efficiency. During cooling operation, the amount of branched refrigerant flowing to the subcooling heat exchanger increases, while the amount of liquid refrigerant flowing to the indoor heat exchanger decreases. However, the decrease in the amount of liquid refrigerant reduces piping resistance, resulting in a smaller decrease in the amount of liquid refrigerant circulating in the indoor heat exchanger. This allows for reliable enhancement of cooling capacity by controlling the opening of the subcooling expansion valve.

[0010] However, the conventional configuration described above has a problem in that the cooling capacity may not be fully exerted due to the layout inside the outdoor unit. Specifically, when the distances between each compressor and the outdoor heat exchanger are different, the amount of heat exchanged between the outdoor air passing through the outdoor heat exchanger and each compressor varies, resulting in differences in the refrigerant discharge temperature of each compressor. In particular, during cooling operation, when each compressor operates at high speed, the compressor farther from the outdoor heat exchanger will reach the refrigerant discharge temperature standard before the compressors closer to the outdoor heat exchanger. This limits the rotation speed of the compressor farther from the outdoor heat exchanger, making it difficult to improve cooling capacity.

[0011] Under these circumstances, the inventors came up with the idea of ​​injecting refrigerants with different dryness levels into each compressor to equalize the refrigerant discharge temperatures of each compressor.The inventors then discovered that realizing this idea posed a problem: the amount of heat exchanged between the refrigerant and the outside air in each branch pipe for injection must be uniform.To solve this problem, the inventors came up with the subject matter of the present disclosure. Therefore, the present disclosure provides an outdoor unit that can inject refrigerants with different dryness levels into each compressor, thereby reducing the difference in refrigerant discharge temperature between the compressors due to layout.

[0012] Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of already well-known matters or redundant description of substantially the same configuration may be omitted. 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.

[0013] (Embodiment 1) The first embodiment will be described below. [1-1.Configuration] [1-1-1. Refrigerant circuit configuration] FIG. 1 is a configuration diagram showing a refrigerant circuit of an air conditioner including an outdoor unit according to a first embodiment of the present disclosure. The air conditioner 100 of the first embodiment has an outdoor unit 110 , an indoor air conditioning unit 150 , a liquid pipe 140 , and a gas pipe 160 . Although FIG. 1 shows an example in which two indoor air conditioning units 150 are connected in parallel, one indoor air conditioning unit 150 or three or more indoor air conditioning units 150 may be connected.

[0014] In this 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. Here, as shown in Fig. 1, the outdoor unit 110 may have a receiver tank 118 on the piping through which the high-pressure refrigerant flows. Also, in this embodiment, within the outdoor unit 110, the liquid piping 140 branches off from the injection piping 120.

[0015] The outdoor unit 110 of this embodiment is configured such that a single outdoor unit 110 is provided with a plurality of compressors, such as a first compressor 111a and a second compressor 111b. The first compressor 111a and the second compressor 111b are mechanical devices that compress a refrigerant. The first compressor 111a draws in a refrigerant through a first suction pipe 115a, compresses it, and discharges the compressed refrigerant to a first discharge pipe 117a. Similarly, the second compressor 111b draws in a refrigerant through a second suction pipe 115b, compresses it, and discharges the compressed refrigerant to a second discharge pipe 117b. The first compressor 111a and the second compressor 111b may be a compressor in which the compression process is housed in a sealed container and which has an injection port in the intermediate pressure chamber, or a two-stage compressor in which a low-pressure side compressor and a high-pressure side compressor are housed in a sealed container. Also, unlike the configuration of this embodiment, two or more compressors may be connected in parallel or in series.

[0016] Four-way valve 112 is a valve that switches the refrigerant flow direction between cooling operation and heating operation of air conditioner 100, and is connected to the junction of first discharge pipe 117a and second discharge pipe 117b and the junction of first suction pipe 115a and second suction pipe 115b. An accumulator 119 for separating the gas and liquid refrigerant is provided at the junction of first suction pipe 115a and second suction pipe 115b. The outdoor heat exchanger 114 is a heat exchanger that exchanges heat between the refrigerant and the outside air surrounding the outdoor heat exchanger 114. Generally, a fin-and-tube type or a microtube type heat exchanger is used as the outdoor heat exchanger 114.

[0017] Furthermore, the first discharge pipe 117a and the second discharge pipe 117b are provided with a first discharge temperature sensor 137a and a second discharge temperature sensor 137b, respectively, which detect the temperature of the refrigerant discharged from each compressor. Similarly, the first suction pipe 115a and the second suction pipe 115b are provided with a first suction temperature sensor 135a and a second suction temperature sensor 135b, respectively, which detect the temperature of the refrigerant sucked into each compressor.

[0018] The injection pipe 120 is provided with a subcooling expansion valve 127 that reduces the pressure of the branched refrigerant branched from the liquid pipe 140, and a subcooling heat exchanger 125 that exchanges heat between the branched refrigerant and the refrigerant in the liquid pipe 140. The subcooling heat exchanger 125 may be a double pipe or a plate heat exchanger. Furthermore, the injection pipe 120 branches into a first branch pipe 121a and a second branch pipe 121b at a branching section 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. For example, grooveless pipes can be used as the first branch pipe 121a and the second branch pipe 121b. A first branch pipe temperature sensor 131a is attached to the first branch pipe 121a to detect the temperature of the refrigerant injected into the compression chamber of the first compressor 111a. Similarly, a second branch pipe temperature sensor is attached to the second branch pipe 121b to detect the temperature of the refrigerant injected into the compression chamber of the second compressor 111b.

[0019] The liquid pipe 140 connecting the outdoor heat exchanger 114 and the indoor heat exchanger 151 is equipped with a liquid temperature sensor 139. The liquid temperature sensor 139 detects the temperature of the refrigerant in the liquid pipe 140 after heat exchange in the subcooling heat exchanger 125. Here, the liquid pipe 140 corresponds to a high-pressure refrigerant pipe.

[0020] Each indoor air conditioning unit 150 includes an indoor heat exchanger 151 that exchanges heat between the indoor air and the refrigerant. Also, as shown in FIG. 1, each indoor air conditioning unit 150 may include an indoor expansion valve 153. Each device provided in the air conditioner 100 is controlled by a controller (not shown).

[0021] [1-1-2.Outdoor unit configuration] The layout of each device inside the outdoor unit 110 will be described below with reference to Figures 2 and 3. Figure 2 is a schematic diagram showing the layout inside the outdoor unit 110 in this embodiment as seen from the front, and Figure 3 is a schematic diagram showing the layout inside the outdoor unit 110 in this embodiment as seen from above.

[0022] As shown in Fig. 2, in this embodiment, an outdoor fan 101 is provided on the top surface of the outdoor unit 110. The outdoor fan 101 is driven by a fan motor (not shown) and sends air inside the outdoor unit 110 to the outside, thereby taking in outside air 103 into the outdoor unit 110 through an outdoor heat exchanger 114. This promotes heat exchange between the outside air 103 and the outdoor heat exchanger 114.

[0023] 2, the branching portion 123 of the injection pipe 120 is provided at a position higher than both the main body of the first compressor 111a and the main body of the second compressor 111b. Furthermore, the first branching pipe 121a and the second branching pipe 121b branching from the branching portion 123 are installed so that the height of the second branching pipe 121b is greater than the height of the first branching pipe 121a. Here, the height of the first branch pipe 121a and the second branch pipe 121b refers to the height of the top of each branch pipe. Hereinafter, the height of the top of the branch pipe will be simply referred to as the height of the branch pipe.

[0024] As shown in Fig. 3, in this embodiment, the outdoor heat exchangers 114 are provided on three of the four sides of the outdoor unit 110. Of the sides of the outdoor unit 110, the sides on which the outdoor heat exchangers 114 are provided allow outside air 103 to be taken into the outdoor unit 110. On the other hand, of the sides of the outdoor unit 110, the sides on which the outdoor heat exchangers 114 are not provided are provided with an operation panel (not shown) and a board (not shown), and therefore become sides that block the flow of air.

[0025] In addition, the top view of the layout inside the outdoor unit 110 in FIG. 3 shows the positional relationship between the first compressor 111a and the second compressor 111b. 3, the first compressor 111a and the outdoor heat exchanger 114 are separated by a distance Ix in the direction of arrow X (hereinafter referred to as the X direction) and a distance Iy in the direction of arrow Y (hereinafter referred to as the Y direction). Similarly, the second compressor 111b and the outdoor heat exchanger 114 are separated by a distance IIx in the X direction and a distance IIy in the Y direction. Here, 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 first compressor 111a and the outdoor heat exchanger 114 are installed so that the distance between them is greater than the distance between the second compressor 111b and the outdoor heat exchanger 114.

[0026] [1-2. Operation] The operation and function of the outdoor unit 110 configured as above and the air conditioner 100 including the outdoor unit 110 will be described.

[0027] During cooling operation of the air conditioner 100, the four-way valve 112 connects the piping where the first discharge pipe 117a and the second discharge pipe 117b join with the outdoor heat exchanger 114. Therefore, the refrigerant compressed by the first compressor 111a and the second compressor 111b flows into the outdoor heat exchanger 114 as a high-temperature, high-pressure gas refrigerant with a discharge superheat degree higher than the saturation temperature at the discharge pressure. The high-temperature, high-pressure gas refrigerant that flows into the outdoor heat exchanger 114 releases heat to the surrounding outside air 103 drawn in by the outdoor fan 101 and condenses, becoming a high-pressure, supercooled liquid refrigerant.

[0028] A portion of the high-pressure supercooled liquid refrigerant that flows through the liquid pipe 140 and has passed through the outdoor heat exchanger 114 branches off and flows into the injection pipe 120, where it is decompressed by the supercooling expansion valve 127. The decompressed refrigerant passes through the supercooling heat exchanger 125, where it exchanges heat with the high-pressure refrigerant in the liquid pipe 140.

[0029] The refrigerant in the injection pipe 120 receives heat by passing through the subcooling heat exchanger 125. This refrigerant is branched from the injection pipe 120 at a branching point 123, passes through a first branch pipe 121a and a second branch pipe 121b, and is injected into the compression chambers of the first compressor 111a and the second compressor 111b. When the amount of heat exchanged 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 compressor is near the saturation line corresponding to point G on the Mollier diagram in FIG. 4.

[0030] On the other hand, the low-pressure refrigerant corresponding to point E in Figure 4 that is 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 becomes a refrigerant in a state corresponding to point H in Figure 3. Therefore, in the compression chamber of each compressor, the refrigerant in the state of point G to be injected and the refrigerant in the pressurized state of point H are mixed together, resulting in a refrigerant in a state corresponding to point I in FIG. That is, the refrigerant in the compression chambers of each compressor, which is at an intermediate pressure, is cooled by the injected refrigerant while being compressed. As a result, the refrigerant discharge temperatures of the first compressor 111a and the second compressor 111b are lower than when the branched refrigerant is not injected into the compression chambers.

[0031] Meanwhile, the high-pressure refrigerant in the liquid pipe 140 releases heat in the subcooling heat exchanger 125, increasing the degree of subcooling. The high-pressure refrigerant that has passed through the subcooling heat exchanger 125 flows from the outdoor unit 110 through the liquid pipe 140 into the indoor air conditioning unit 150. The refrigerant that has flowed into the indoor air conditioning unit 150 is decompressed by the indoor expansion valve 153, and becomes a gas-liquid two-phase refrigerant. Of the gas-liquid two-phase refrigerant, the liquid refrigerant absorbs heat from the indoor air in the indoor heat exchanger 151 and evaporates, becoming a low-pressure superheated gas. The indoor air that absorbs heat here lowers the indoor temperature, so the air conditioner 100 functions as a cooling device.

[0032] The refrigerant in a heated gas state passes through the gas pipe 160 from the indoor air conditioning unit 150 and returns to the outdoor unit 110. The gas refrigerant that has 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.

[0033] On the other hand, when the air conditioner 100 is in heating operation, the four-way valve 112 connects the indoor heat exchanger 151 to the piping where the first discharge pipe 117a and the second discharge pipe 117b join via the gas pipe 160. Therefore, the refrigerant compressed by the first compressor 111a and the second compressor 111b becomes a high-temperature, high-pressure gas refrigerant with a discharge superheat degree higher than the saturation temperature at the discharge pressure, and flows into the indoor air-conditioning unit 150. The gas refrigerant that flows into the indoor air-conditioning unit 150 releases heat to the indoor air in the indoor heat exchanger 151 and condenses, becoming a high-pressure, supercooled liquid refrigerant. The indoor air that receives heat here raises the indoor temperature, so the air conditioner 100 functions as a heating device.

[0034] The high-pressure refrigerant coming out of the indoor heat exchanger 151 passes through the liquid pipe 140 and flows into the outdoor unit 110. A portion of the high-pressure and supercooled liquid refrigerant that has entered the outdoor unit 110 branches off and flows into the injection pipe 120, where it is decompressed by the supercooling expansion valve 127. The decompressed refrigerant passes through the subcooling heat exchanger 125 and exchanges heat with the high-pressure refrigerant in the liquid pipe 140 .

[0035] The refrigerant in the injection pipe 120 receives heat in the subcooling heat exchanger 125. The refrigerant in this state is branched from the injection pipe 120 at the branching portion 123, passes through the first branch pipe 121a and the second branch pipe 121b, and is injected into the compression chambers of the first compressor 111a and the second compressor 111b. When the amount of heat exchanged 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 compressor is near the saturation line corresponding to point G on the Mollier diagram in FIG. 4.

[0036] On the other hand, the low-pressure refrigerant corresponding to point E in Figure 4 that is 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 becomes a refrigerant in a state corresponding to point H in Figure 3. Therefore, in the compression chamber of each compressor, the refrigerant in the state of point G to be injected and the refrigerant in the pressurized state of point H are mixed together, resulting in a refrigerant in a state corresponding to point I in FIG. That is, the refrigerant in the compression chambers of each compressor, which is at an intermediate pressure, is cooled by the injected refrigerant while being compressed. As a result, the refrigerant discharge temperatures of the first compressor 111a and the second compressor 111b are lower than when the branched refrigerant is not injected into the compression chambers.

[0037] On the other hand, the degree of subcooling of the high-pressure refrigerant in the liquid pipe 140 increases as a result of releasing heat in the subcooling heat exchanger 125. The high-pressure refrigerant that has passed through the subcooling heat exchanger 125 is decompressed by the outdoor expansion valve 116 and becomes a gas-liquid two-phase refrigerant. Of the gas-liquid two-phase refrigerant, the liquid refrigerant absorbs heat from the surrounding outside air 103 in the outdoor heat exchanger 114 and evaporates, becoming a low-pressure superheated gas. 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.

[0038] During the cooling operation and heating operation, the outdoor fan 101 in the outdoor unit 110 actually rotates, promoting heat exchange between the outdoor heat exchanger 114 and the outside air 103 . Here, the outdoor air 103 sucked in by the outdoor fan 101 passes through the outdoor heat exchanger 114, but the wind speed of the outdoor air 103 inside the outdoor unit 110 is high above the outdoor heat exchanger 114, close to the outdoor fan 101, and low below, far from the outdoor fan 101.

[0039] In this embodiment, second branch pipe 121b is disposed at a position where it comes into contact with outside air having a higher wind speed than first branch pipe 121a. Specifically, by installing second branch pipe 121b so that its height is greater than that of first branch pipe 121a, the refrigerant in second branch pipe 121b exchanges heat with more outside air than the refrigerant in first branch pipe 121a. Therefore, the refrigerant in second branch pipe 121b receives more heat and has a higher proportion of gas components than the refrigerant in first branch pipe 121a. Conversely, the refrigerant in first branch pipe 121a receives less heat and has a higher proportion of liquid components than the refrigerant in second branch pipe 121b.

[0040] 4 illustrates a Mollier diagram for the case where the amount of heat exchanged between the refrigerant and the outside air 103 is equal in the first branch pipe 121a and the second branch pipe 121b. This corresponds to the case where the heights of the first branch pipe 121a and the second branch pipe 121b are equal. However, in reality, when the layout inside the outdoor unit 110 of this embodiment is taken into consideration, the amount of heat exchanged between the refrigerant and the air differs between the first branch pipe 121a and the second branch pipe 121b.

[0041] Figure 5 shows a Mollier diagram of the refrigerant passing through the first compressor 111a during operation of the air conditioner 100, when the layout inside the outdoor unit 110 is reflected and the height of the first branch pipe 121a is installed to be smaller than in the case of Figure 4. 4, the refrigerant passing through first branch pipe 121a to be injected into first compressor 111a exchanges heat with outside air 103, which has a slower wind speed, and therefore the amount of heat exchanged with outside air 103 is reduced. Therefore, the quality fraction of the refrigerant passing through first branch pipe 121a is lower than in the case of FIG. 4, and the state corresponds to point Ga in FIG. 5. Therefore, the refrigerant in a state corresponding to point Ia in which the refrigerant in a state corresponding to point H in Fig. 5 and the refrigerant in a state corresponding to point Ga are mixed during compression in the compression chamber of the first compressor 111a has a lower temperature than the refrigerant in a state corresponding to point I in Fig. 4. As a result, the refrigerant discharged from the first compressor 111a is in a state corresponding to point Aa, and has a lower temperature than the refrigerant in a state corresponding to point A.

[0042] FIG. 6 shows a Mollier diagram of the refrigerant passing through the second compressor 111b during operation of the air conditioner 100 when the second branch pipe 121b is installed so that its height is greater than that in FIG. 4, the refrigerant passing through second branch pipe 121b to be injected into second compressor 111b exchanges heat with outside air 103 having a high wind speed, thereby increasing the amount of heat exchanged with outside air 103. Therefore, the dryness fraction of the refrigerant passing through second branch pipe 121b is higher than in the case of FIG. 4, and the state corresponds to point Gb in FIG. 6. Therefore, the refrigerant in a state corresponding to point Ib in Fig. 6, which is a mixture of the refrigerant in a state corresponding to point H in Fig. 6 and the refrigerant in a state corresponding to point Gb, being compressed in the compression chamber of the second compressor 111b, has a higher temperature than the refrigerant in a state corresponding to point I in Fig. 4. As a result, the refrigerant discharged from the second compressor 111b is in a state corresponding to point Ab, and has a higher temperature than the refrigerant in a state corresponding to point A.

[0043] Furthermore, if the branching section 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 branching section 123 becomes equal to the height of the first compressor 111a and the second compressor 111b. Therefore, the outdoor 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, resulting in non-uniform wind speed and temperature of the outdoor air 103 around the first compressor 111a and the second compressor 111b. As a result, the temperature of the refrigerant discharged from the first compressor 111a and the second compressor 111b to the first discharge pipe 117a and the second discharge pipe 117b becomes non-uniform. However, in this embodiment, the branching section 123 is installed above the upper ends of the first compressor 111a and the second compressor 111b. As a result, the height of the first branch pipe 121a and the second branch pipe 121b, through which the refrigerant passes after the branching section 123, is greater than the height of the first compressor 111a and the second compressor 111b. Therefore, the outdoor air 103 drawn 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, or other structures. This prevents uneven wind speed and temperature of the outdoor air 103 around the first compressor 111a and the second compressor 111b. As a result, the discharge temperatures of the first discharge pipe 117a and the second discharge pipe 117b of the first compressor 111a and the second compressor 111b are uniform.

[0044] Furthermore, in the present disclosure, the amount of heat exchanged between the first branch pipe 121a and the second branch pipe 121b and the outside air 103 varies depending on the operation mode of the air conditioner 100. The difference in heat exchange amount between the operation modes when R32 refrigerant is used as the refrigerant for the air conditioner 100 will be exemplified below. When the air conditioner 100 performs cooling operation at an outdoor temperature of 35°C so that the blown temperature from the indoor air conditioning unit 150 is 15°C, the refrigerant in the low-pressure section has a temperature of 10°C, which is 5K lower than the blown temperature from the indoor air conditioning unit 150, and a pressure of 1.1 MPa. Furthermore, the pressure of the refrigerant to be injected is 1.5 MPa, which is 1.4 times the pressure in the low-pressure section, and a temperature of 21°C. Then, the temperature difference between the temperature of the refrigerant flowing through the first branch pipe 121a and the second branch pipe 121b and the outdoor air temperature is approximately 14K.

[0045] On the other hand, when the air conditioner 100 performs heating operation at an outdoor temperature of 7°C, the temperature of the refrigerant in the low-pressure section is approximately -0.5°C, which is the temperature at which the evaporator frosts, and the pressure is 0.8 MPa. Furthermore, the pressure of the refrigerant to be injected is 1.1 MPa, which is 1.4 times the pressure in the low-pressure section, and the temperature is 10°C. In this case, the temperature difference between the outdoor air temperature and the temperature of the refrigerant flowing through the first branch pipe 121a and the second branch pipe 121b is approximately 3K. Therefore, the temperature 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 during cooling operation than during heating operation. Therefore, the amount of heat exchange that takes place between the outside air 103 and the refrigerant flowing through the first branch pipe 121a and the second branch pipe 121b is greater during cooling operation of the air conditioner 100 than during heating operation.

[0046] [1-3. Effects, etc.] In this embodiment, the outdoor unit 110 includes a first compressor 111a, a second compressor 111b, an outdoor heat exchanger 114, a liquid pipe 140, an injection pipe 120 branching from the liquid pipe 140, and an outdoor fan 101 installed above the outdoor heat exchanger 114. The distance between the second compressor 111b and the outdoor heat exchanger 114 is shorter than the distance between the first compressor 111a and the outdoor heat exchanger 114. The injection pipe 120 has a first branch pipe 121a and a second branch pipe 121b branched at a branch point 123, and 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. Furthermore, the branching section 123 is installed above the first compressor 111a and the second compressor 111b, and is installed so that the height of the second branching pipe 121b is greater than the height of the first branching pipe 121a.

[0047] According to this, the outdoor air 103 sucked in by the outdoor fan 101 passes through the outdoor heat exchanger 114, but the wind speed of the outdoor air 103 inside the outdoor unit 110 is high above the outdoor heat exchanger 114 close to the outdoor fan 101 and low below, far from the outdoor fan 101. Therefore, by installing second branch pipe 121b so that its height is greater than that of first branch pipe 121a, the refrigerant in second branch pipe 121b exchanges heat with more outside air than the refrigerant in first branch pipe 121a. Therefore, the refrigerant in second branch pipe 121b receives more heat and has a higher proportion of gas components than the refrigerant in first branch pipe 121a.

[0048] That is, since the refrigerant passing through first branch pipe 121a is installed so that the height of first branch pipe 121a is smaller than in the case of Fig. 4, it exchanges heat with outside air 103, which has a slower wind speed, and therefore the amount of heat exchanged with outside air 103 is reduced. Therefore, the quality fraction of the refrigerant passing through first branch pipe 121a is lower than in the case of Fig. 4, and the refrigerant is injected into first compressor 111a in a state corresponding to point Ga in Fig. 5. Therefore, the refrigerant in a state corresponding to point Ia in which the refrigerant in a state corresponding to point H in Fig. 5 and the refrigerant in a state corresponding to point Ga are mixed during compression in the compression chamber of the first compressor 111a has a lower temperature than the refrigerant in a state corresponding to point I in Fig. 4. As a result, the refrigerant discharged from the first compressor 111a is in a state corresponding to point Aa, and has a lower temperature than the refrigerant in a state corresponding to point A.

[0049] Furthermore, since the refrigerant passing through second branch pipe 121b is installed so that the height of second branch pipe 121b is greater than in the case of Fig. 4, the refrigerant exchanges heat with outside air 103, which has a high wind speed, and therefore the amount of heat exchanged with outside air 103 is increased. Therefore, the refrigerant passing through second branch pipe 121b has a higher dryness fraction than in the case of Fig. 4, and is in a state corresponding to point Gb in Fig. 6 before being injected into second compressor 111b. Therefore, the refrigerant in a state corresponding to point Ib in Fig. 6, which is a mixture of the refrigerant in a state corresponding to point H in Fig. 6 and the refrigerant in a state corresponding to point Gb, being compressed in the compression chamber of the second compressor 111b, has a higher temperature than the refrigerant in a state corresponding to point I in Fig. 4. As a result, the refrigerant discharged from the second compressor 111b is in a state corresponding to point Ab, and has a higher temperature than the refrigerant in a state corresponding to point A.

[0050] Therefore, the amount of decrease in the refrigerant discharge temperature at each compressor due to the injection of refrigerant from each branch pipe can be large in the first compressor 111a and small in the second compressor 111b. Therefore, the first compressor 111a, which is far from the outdoor heat exchanger 114 and therefore tends to have a high refrigerant discharge temperature, can be operated at high rotation speed like the second compressor 111b, thereby improving cooling capacity.

[0051] (Embodiment 2) The second embodiment will be described below. [2-1.Configuration] [2-1-1. Refrigerant circuit configuration] The configuration of the refrigerant circuit of the air conditioner 100 including the outdoor unit 110 of embodiment 2 is as shown in Fig. 1, similar to embodiment 1. Therefore, a description of the configuration of the refrigerant circuit will be omitted, and only the layout inside the outdoor unit 110 will be described below.

[0052] [2-1-2. Layout inside the outdoor unit] The layout inside the outdoor unit 110 in the second embodiment will be described below.

[0053] Fig. 7 is a schematic diagram showing the layout of the outdoor unit 110 according to the second embodiment as seen from the front. As shown in Fig. 7, in the outdoor unit 110 according to the second embodiment, the height of the second branch pipe 121b connected to the second compressor 111b is set to be greater than the heights of both the second discharge pipe 117b and the second suction pipe 115b. On the other hand, the height of the first branch pipe 121a connected to the first compressor 111a is set to be less than the heights of both the first discharge pipe 117a and the first suction pipe 115a. In addition, the receiver tank 118 has a shape that extends in the height direction in order to reduce the bottom area of ​​the outdoor unit 110.

[0054] [2-2. Operation] The following describes the operation and function of the air conditioner 100 including the outdoor unit 110 configured as above. Operations that depend on the configuration of the refrigerant circuit are omitted here, as they are the same as in the first embodiment.

[0055] The receiver tank 118 in the outdoor unit 110 stores supercooled high-pressure liquid refrigerant inside and adjusts the pressure in the refrigerant circuit, thereby eliminating the difference in the amount of refrigerant required between cooling and heating operations and the difference in the amount of surplus refrigerant depending on the intensity of the cooling / heating operation.

[0056] As described in the explanation of the first embodiment, when the air conditioner 100 is operating, the outdoor air 103 drawn in by the outdoor fan 101 passes through the outdoor heat exchanger 114. The wind speed of the outdoor air 103 is high above the outdoor heat exchanger 114, which is close to the outdoor fan 101, and is low below, which is far from the outdoor fan 101. Furthermore, as described in the description of the first embodiment, the flow of the outside air 103 that has flowed into the outdoor unit 110 is blocked by the structure including the first compressor 111a and the second compressor 111b.

[0057] In the second embodiment, the height of second branch pipe 121b is greater than both the height of second discharge pipe 117b and the height of second suction pipe 115b, and therefore no piping blocks the connection between second branch pipe 121b and outside air 103. Therefore, the amount of heat exchanged between the refrigerant in second branch pipe 121b and outside air 103 is further increased compared to when the height of second branch pipe 121b is not greater than both the height of second discharge pipe 117b and the height of second suction pipe 115b. This further increases the gas component of the refrigerant injected from second branch pipe 121b to second compressor 111b. On the other hand, the height of first branch pipe 121a is smaller than both the height of first discharge pipe 117a and the height of first suction pipe 115a. Therefore, compared to when the height of first branch pipe 121a is not smaller than both the height of first discharge pipe 117a and the height of first suction pipe 115a, the amount of heat exchanged between the refrigerant in first branch pipe 121a and outside air 103 is reduced. This further increases the liquid component of the refrigerant injected from first branch pipe 121a to first compressor 111a.

[0058] That is, because the height of second branch pipe 121b is greater than both the heights of second discharge pipe 117b and second suction pipe 115b, the refrigerant at the outlet of second branch pipe 121b has a higher quality than that at point Gb in FIG. 6 in the first embodiment. This refrigerant is injected into second compressor 111b and mixed with the pressurized refrigerant in second compressor 111b in a state corresponding to point H in FIG. 6, resulting in a refrigerant with a higher quality than that at point Ib. This refrigerant is hotter than the refrigerant in a state corresponding to point Ib in FIG. 6. Therefore, the temperature of the refrigerant discharged from second compressor 111b to second discharge pipe 117b becomes even higher.

[0059] Furthermore, because the height of first branch pipe 121a is smaller than the heights of first discharge pipe 117a and first suction pipe 115a, the refrigerant at the outlet of first branch pipe 121a has a lower quality fraction than that of point Ga in FIG. 5 in the first embodiment. This refrigerant is injected into first compressor 111a and mixed with the refrigerant pressurized in first compressor 111a in a state corresponding to point H in FIG. 5, resulting in a refrigerant with an even lower quality fraction than that of the refrigerant in a state corresponding to point Ia in FIG. 5. This refrigerant is at an even lower temperature than the refrigerant in a state corresponding to point Ia in FIG. 5. Therefore, the temperature of the refrigerant discharged from first compressor 111a to first discharge pipe 117a is further reduced.

[0060] 8 is a graph in which the vertical axis represents the height at which the wind speed is measured relative to the product height of the outdoor unit 110, and the horizontal axis represents the wind speed of the outside air 103 drawn into the outdoor unit 110. In FIG. In Figure 8, the wind speed of the outdoor air 103 is almost uniform at wind speed measurement heights below approximately half the product height of the outdoor unit 110, but above approximately half the product height of the outdoor unit 110, the wind speed of the outdoor air 103 increases the higher the position. That is, by setting the height of second branch pipe 121b to approximately half the product height of outdoor unit 110 or more, the volume of outside air 103 increases as the height increases, and the refrigerant in second branch pipe 121b can exchange heat with the fast-flowing outside air 103, increasing the amount of gas components. Therefore, by installing second branch pipe 121b at a position higher than second discharge pipe 117b and second suction pipe 115b, the refrigerant injected from second branch pipe 121b to second compressor 111b is in the gas phase. Therefore, the temperature of the refrigerant mixed with the pressurized refrigerant in second compressor 111b increases, and as a result, the temperature of the refrigerant discharged to second discharge pipe 117b of second compressor 111b increases.

[0061] [2-3. Effects, etc.] As described above, in this embodiment, the first compressor 111a in the outdoor unit 110 has the first discharge pipe 117a and the first suction pipe 115a. The second compressor 111b has the second discharge pipe 117b and the second suction pipe 115b. Furthermore, the second branch pipe 121b of the second compressor 111b is installed at a position higher than both the second discharge pipe 117b and the second suction pipe 115b.

[0062] According to this, the height of second branch pipe 121b is greater than both the height of second discharge pipe 117b and the height of second suction pipe 115b, and therefore no piping blocks the connection between second branch pipe 121b and outside air 103. Therefore, compared to a case where the height of second branch pipe 121b is not greater than both the height of second discharge pipe 117b and the height of second suction pipe 115b, the amount of heat exchanged between the refrigerant in second branch pipe 121b and outside air 103 is further increased. This further increases the gas component of the refrigerant injected from second branch pipe 121b to second compressor 111b. On the other hand, the height of first branch pipe 121a is smaller than both the height of first discharge pipe 117a and the height of first suction pipe 115a. Therefore, the amount of heat exchanged between the refrigerant in first branch pipe 121a and outside air 103 is reduced compared to when the height of first branch pipe 121a is not smaller than both the height of first discharge pipe 117a and first suction pipe 115a. This further increases the liquid component of the refrigerant injected from first branch pipe 121a to first compressor 111a.

[0063] That is, because the height of second branch pipe 121b is greater than both the heights of second discharge pipe 117b and second suction pipe 115b, the refrigerant at the outlet of second branch pipe 121b has a higher quality than that at point Gb in FIG. 6 in the first embodiment. This refrigerant is injected into second compressor 111b and mixed with the pressurized refrigerant in second compressor 111b in a state corresponding to point H in FIG. 6, resulting in a refrigerant with a higher quality than that at point Ib. This refrigerant is hotter than the refrigerant in a state corresponding to point Ib in FIG. 6. Therefore, the temperature of the refrigerant discharged from second compressor 111b to second discharge pipe 117b becomes even higher.

[0064] Furthermore, because the height of first branch pipe 121a is smaller than the heights of first discharge pipe 117a and first suction pipe 115a, the refrigerant at the outlet of first branch pipe 121a has a lower quality fraction than that of point Ga in FIG. 5 in the first embodiment. This refrigerant is injected into first compressor 111a and mixed with the refrigerant pressurized in first compressor 111a in a state corresponding to point H in FIG. 5, resulting in a refrigerant with an even lower quality fraction than that of the refrigerant in a state corresponding to point Ia in FIG. 5. This refrigerant is at an even lower temperature than the refrigerant in a state corresponding to point Ia in FIG. 5. Therefore, the temperature of the refrigerant discharged from first compressor 111a to first discharge pipe 117a decreases.

[0065] Therefore, the amount of decrease in the refrigerant discharge temperature in the second compressor 111b due to the injection of the refrigerant from the second branch pipe 121b can be further reduced. Therefore, particularly in the case of the outdoor unit 110 with a complex 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 high due to the layout, can be further reduced.

[0066] Furthermore, as in this 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. This further increases the liquid component of the refrigerant injected from the first branch pipe 121a into the first compressor 111a. Therefore, the amount of decrease in the refrigerant discharge temperature in the first compressor 111a due to the injection of the refrigerant from the first branch pipe 121a can be further increased. Therefore, the refrigerant discharge temperature of the first compressor 111a, which tends to become high, can be further reduced, and the first compressor 111a can be operated at a high rotation speed, thereby improving the cooling capacity.

[0067] (Other embodiments) As described above, the first and second embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. Furthermore, it is also possible to combine the components described in the first and second embodiments to create new embodiments. Therefore, other embodiments will be exemplified below.

[0068] In the first and second embodiments, grooveless pipes have been described as an example of the first branch pipe 121a and the second branch pipe 121b. However, in the present disclosure, 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 is changed depending on the arrangement of the branch pipes, thereby suppressing the difference in discharge temperature between each compressor. Therefore, it is sufficient that the arrangement of the first branch pipe 121a and the second branch pipe 121b results in a difference in heat exchange. Therefore, the first branch pipe 121a and the second branch pipe 121b are not limited to grooveless pipes. However, using grooveless pipes as the piping of the first branch pipe 121a and the second branch pipe 121b can reduce manufacturing costs.

[0069] Furthermore, the material of each branch pipe may be changed, or a grooved pipe or a fin-and-tube pipe may be used as the branch pipe. For example, a plain pipe made of a highly insulating material 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, a large difference in the amount of heat exchange in each branch pipe can be created, which can increase the difference in the amount of temperature drop due to the injected refrigerant, and further equalize the discharge temperature of each compressor.

[0070] In the first and second embodiments, as an example of a means for changing the refrigerant discharge temperature of each compressor, a difference between the amount of heat exchanged between first branch pipe 121a and outside air 103 and the amount of heat exchanged between second branch pipe 121b and outside air 103 has been described. The means for changing the refrigerant discharge temperature of each compressor may be any means that can change the enthalpy of the refrigerant compressed in each compressor when it flows into the compressor. Therefore, the means for changing the refrigerant discharge temperature of each compressor is not limited to changing the heights of first branch pipe 121a and second branch pipe 121b.

[0071] In addition, as a means for changing the refrigerant discharge temperature of each compressor, the first suction pipe 115a of the first compressor 111a may be installed higher than the first suction pipe 115a so that the liquid component is increased and the second suction pipe 115b of the second compressor 111b is installed so that the gas component is increased. The horizontal arrangement of first branch pipe 121a and second branch pipe 121b may also be changed. In this case, first branch pipe 121a may be located away from outdoor heat exchanger 114 or in an area where the flow of outdoor air 103 is blocked by a structure so as to reduce the amount of heat exchanged with outdoor air 103, thereby lowering the refrigerant discharge temperature of first compressor 111a. Conversely, second branch pipe 121b may be located closer to outdoor heat exchanger 114 or in an area where the flow of outdoor air 103 is not blocked by a structure so as to increase the amount of heat exchanged with outdoor air 103, thereby raising the refrigerant discharge temperature of second compressor 111b. Therefore, for example, the first branch pipe 121a and the second branch pipe 121b may be installed so that the distance between the second branch pipe 121b and the outdoor heat exchanger 114 is shorter than the distance between the first branch pipe 121a and the outdoor heat exchanger 114.

[0072] In the first and second embodiments, the outdoor fan 101 is installed above the outdoor heat exchanger 114. The outdoor fan 101 may be installed at any position that can promote heat exchange in the outdoor heat exchanger 114. Therefore, the installation position of the outdoor fan 101 is not limited to an upper position. Therefore, the outdoor fan 101 can also be installed in parallel with the outdoor heat exchanger 114. In this case, the second branch pipe 121b is arranged in a location with a large air volume, and the first branch pipe 121a is arranged in a location with a small air volume, thereby making the refrigerant discharge temperature of each compressor uniform. In this case, the air volume distribution of the outside air 103 inside the outdoor unit 110 differs from when the outdoor fan 101 is installed above, and therefore the layout of each branch pipe also differs from when the outdoor fan 101 is installed above.

[0073] It should be noted that the above-described embodiments are intended to illustrate the technology of the present disclosure, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents. [Industrial Applicability]

[0074] The present disclosure can be suitably used as an outdoor unit that can eliminate differences in discharge temperature between compressors due to differences in layout. [Explanation of symbols]

[0075] 100 Air conditioner 101 Outdoor fan 103 Outside Air 110 Outdoor unit 111a No. 1 compressor 111b Second compressor 112 Four-way valve 114 Outdoor heat exchanger 115a 1st suction pipe 115b 2nd suction pipe 116 Outdoor expansion valve 117a 1st discharge pipe 117b 2nd discharge pipe 118 Receiver Tank 119 Accumulator 120 Injection piping 121 Second branch pipe 121a First branch pipe 121b Second branch pipe 123 Branch 125 Cooling heat exchanger 127 Cooling expansion valve 131a First branch pipe temperature sensor 135a First intake temperature sensor 135b Second intake 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 heat exchanger; a first compressor; a second compressor that is closer to the outdoor heat exchanger than the first compressor; High-pressure refrigerant piping; an injection pipe branched from the high-pressure refrigerant pipe; an outdoor fan installed above the outdoor heat exchanger; Equipped with the injection pipe has a first branch pipe and a second branch pipe branched at a branching portion, 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 branching portion is installed above the first compressor and the second compressor, The second branch pipe is installed at a higher position than the first branch pipe. An outdoor unit characterized by:

2. the first compressor has a first discharge pipe and a first suction pipe; the second compressor has a second discharge pipe and a second suction pipe; The second branch pipe is disposed at a position higher than both the second discharge pipe and the second suction pipe.

2. The outdoor unit according to claim 1.

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