Outdoor unit and refrigeration cycle system

Abstract

To provide an outdoor unit and a refrigeration cycle device having branch pipes that can suppress strength reduction even when brazing is performed in a furnace. [Solution] The outdoor unit of the refrigeration cycle device includes an outdoor heat exchanger 34 having copper heat transfer tubes, a main pipe 42 made of iron, an iron alloy, or stainless steel, and a branch pipe 41 consisting of branch pipes 43 that branch off from the main pipe 42 and are connected to the heat transfer tubes 40, wherein at least a portion of the branch pipe 43 has copper alloy piping containing one or more alloying elements selected from cobalt, tin, zinc, nickel, zirconium, and iron.

Description

Technical Field

[0001] This application relates to an outdoor unit and a refrigeration cycle device.

Background Art

[0002] In recent years, due to the increasing demand for copper such as that accompanying the spread of electronic devices, the price of copper has been soaring. Since copper is excellent in thermal conductivity, workability, and corrosion resistance, it is used for refrigerant pipes and the like of refrigeration cycle devices such as air conditioners. However, this soaring price will compress profits, so using other materials instead of copper has been under consideration.

[0003] For example, as the heat transfer tube for the heat exchanger of an air conditioner, using a copper alloy tube containing cobalt (Co), tin (Sn), zinc (Zn), nickel (Ni), and phosphorus (P), or making the main header of the air collector pipe connected to the heat transfer tube group of the heat exchanger of an air conditioning system a stainless steel tube has been proposed (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described in Patent Document 2 above, when manufacturing a sub-assembly product in which the main header (main pipe) of the air collector pipe (branch pipe) connected to the heat exchanger is a stainless steel pipe, and the branch pipes branching from the main pipe and the pipes connected to the tip of the main pipe are made of copper pipes by furnace brazing, the temperature inside the furnace will be exposed to a high temperature environment of about 800 to 1200 °C for a long time. In the copper pipe part, the crystals become coarsened, and the tensile strength and fatigue strength are significantly reduced.

[0006] The main pipe expands and contracts when the refrigerant temperature changes rapidly, such as during defrosting or when starting heating in a low-temperature environment. At this time, differences in the amount of expansion and contraction occur between the main pipe and the branch pipes, which can generate significant stress in the branch pipes.

[0007] Therefore, if copper pipes whose strength has been reduced by furnace brazing are used for branch pipes, there is a high possibility that they will not be able to withstand the stress generated by the expansion and contraction mentioned above, resulting in a fatal failure such as breakage.

[0008] Therefore, there is a need for an outdoor unit and refrigeration cycle device that have branch pipes that can suppress the reduction in strength even when brazing is performed in a furnace. [Means for solving the problem]

[0009] In view of the above problems, the present invention relates to an outdoor unit for a refrigeration cycle device, A heat exchanger having copper heat transfer tubes, A branch pipe consisting of a main pipe made of iron, iron alloy, or stainless steel, and branch pipes that branch off from the main pipe and connect to heat transfer tubes. Includes, An outdoor unit is provided, in which at least a portion of the branch pipes has piping made of a copper alloy containing one or more alloying elements selected from cobalt, tin, zinc, nickel, zirconium, and iron.

[0010] Furthermore, a refrigeration cycle system equipped with an outdoor unit, The outdoor unit, A heat exchanger having copper heat transfer tubes, A branch pipe consisting of a main pipe made of iron, iron alloy, or stainless steel, and branch pipes that branch off from the main pipe and connect to heat transfer tubes. Includes, A refrigeration cycle device is provided, in which at least a portion of the branch pipes are piping made of a copper alloy containing one or more alloying elements selected from cobalt, tin, zinc, nickel, zirconium, and iron. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an outdoor unit and a refrigeration cycle device having branch pipes that can suppress a decrease in strength even when brazing is performed in a furnace. [Brief explanation of the drawing]

[0012] [Figure 1] This diagram shows an example of the configuration of an air conditioning system as an example of a refrigeration cycle system. [Figure 2] A diagram showing in detail the configuration around the outdoor heat exchanger that makes up the outdoor unit. [Figure 3] A diagram showing an example of a branch pipe configuration. [Figure 4] An S / N diagram showing the results of a bending fatigue test. [Modes for carrying out the invention]

[0013] A refrigeration cycle system is a device that continuously cools or heats a fluid by circulating a refrigerant within the system while changing its pressure and state as a heat transfer medium, and by exchanging heat with the circulating refrigerant. Examples include refrigerators and air conditioning systems. In the following description, a refrigeration cycle system will be explained as an air conditioning system, but it is not limited to air conditioning systems.

[0014] Figure 1 shows an example of the configuration of an air conditioning system. The air conditioning system 10 includes an indoor unit 11, which is installed in the space (indoors) where air conditioning is performed; an outdoor unit 12, which is installed outside; and a controller operated by the user. The air conditioning system 10 performs air conditioning by circulating a refrigerant between the indoor unit 11 and the outdoor unit 12 and exchanging heat with the indoor air, which is the fluid to be cooled or heated. For this reason, the indoor unit 11 and the outdoor unit 12 are connected by refrigerant piping in order to circulate the refrigerant.

[0015] The indoor unit 11 and the outdoor unit 12 may each be composed of two or more units, and two or more indoor units 11 may be connected to one outdoor unit 12. As the refrigerant, hydrofluorocarbon (HFC) or hydrofluoroolefin (HFO) can be used. Examples of HFC types include R410A, R32, etc. Examples of HFO types include R1234yf, etc.

[0016] The indoor unit 11 communicates with the controller and receives various signals such as an operation command, a stop command, a command to change the set temperature, and a command to change the operation mode. The indoor unit 11 and the controller may be connected by a cable and communicate wired, or may communicate wirelessly using infrared rays or the like. The indoor unit 11 is connected to the outdoor unit 12 via a communication line and cooperates with the outdoor unit 12 to perform indoor air conditioning.

[0017] The indoor unit 11 receives an operation command from the controller and starts up, and instructs the outdoor unit 12 to start up. After starting up, the outdoor unit 12 adjusts the rotation speed of the compressor, the opening degree of the outdoor expansion valve, etc., and controls the circulation amount of the refrigerant, etc., so that the indoor temperature becomes the set temperature.

[0018] The indoor unit 11 includes an indoor heat exchanger 20, an indoor fan 21, and an indoor fan motor 22 as a power device. The indoor fan 21 is driven by the indoor fan motor 22, takes in indoor air, and sends it into the indoor heat exchanger 20. The indoor heat exchanger 20 has a heat transfer pipe through which the refrigerant flows inside, and is configured such that the sent-in air contacts the surface of the heat transfer pipe to perform heat exchange. The air heat-exchanged by the indoor heat exchanger 20 is discharged into the room.

[0019] In addition, the indoor unit 11 can be provided with various sensors for measuring the indoor temperature, etc., and an indoor expansion valve, etc.

[0020] The outdoor unit 12 comprises a compressor 30, an accumulator 31, a four-way valve 32, an outdoor expansion valve 33, an outdoor heat exchanger 34, an outdoor fan 35, and an outdoor fan motor 36 as a power source. The compressor 30 is driven by the compressor motor and compresses low-pressure gaseous refrigerant, discharging it as high-pressure gaseous refrigerant. The accumulator 31 separates gas and liquid to prevent liquid from entering the compressor 30.

[0021] The four-way valve 32 is a valve that switches the flow path of the refrigerant according to the operating state (operating mode) of the air conditioning unit 10. The operating modes include cooling mode, heating mode, and fan mode. The outdoor expansion valve 33 is a valve that expands the high-pressure refrigerant and adjusts the pressure and flow rate of the refrigerant. The outdoor fan 35 is driven by the outdoor fan motor 36 and takes in outside air and sends it to the outdoor heat exchanger 34. The outdoor heat exchanger 34, like the indoor heat exchanger 20, has heat transfer tubes through which the refrigerant flows, and is configured so that the supplied air comes into contact with the surface of the heat transfer tubes to perform heat exchange. The air that has undergone heat exchange by the outdoor heat exchanger 34 is discharged to the outside.

[0022] The outdoor unit 12 is further equipped with a control device 37. The control device 37 is connected to the compressor 30, the four-way valve 32, the outdoor expansion valve 33, the indoor fan motor 22, and the outdoor fan motor 36, and controls them. Specifically, it controls the rotational speed of the compressor motor, the opening degree of the outdoor expansion valve 33, and the rotational speeds of the indoor fan motor 22 and the outdoor fan motor 36. Various sensors are also attached to the outdoor unit 12 to control these. The control device 37 performs these controls based on the information detected by the various sensors. Note that the control device 37 is not limited to the outdoor unit 12; it may also be installed in the indoor unit 11, or its function may be divided into two parts and installed in both the indoor unit 11 and the outdoor unit 12, or it may not be mounted inside the indoor unit 11 or the outdoor unit 12, but may be a separate device located in a different location from the indoor unit 11 and the outdoor unit 12.

[0023] During cooling operation, the indoor heat exchanger 20 is used as an evaporator and the outdoor heat exchanger 34 is used as a condenser. Therefore, the control device 37 circulates the refrigerant sealed in the system in the following order, as shown by the arrows: compressor 30, four-way valve 32, outdoor heat exchanger 34, outdoor expansion valve 33, indoor heat exchanger 20, four-way valve 32, accumulator 31, and compressor 30.

[0024] The compressor 30 compresses the refrigerant (refrigerant gas) in a low-temperature, low-pressure gaseous state and discharges it as a high-temperature, high-pressure refrigerant gas. The outdoor heat exchanger 34 exchanges heat with the outside air, cooling and condensing the refrigerant gas. The outdoor expansion valve 33 expands the refrigerant, adjusts the pressure of the refrigerant flowing to the evaporator, and also adjusts the flow rate of the refrigerant to maintain a constant superheating degree at the evaporator outlet. The superheating degree indicates how many degrees higher it is than the saturation temperature and is an indicator of the degree of superheating.

[0025] The indoor heat exchanger 20 exchanges heat with the indoor air and returns the refrigerant gas, heated to the above-mentioned superheat level, to the outdoor unit 12. The refrigerant gas returned from the indoor heat exchanger 20 is sent to the accumulator 31 through the four-way valve 32 and then returned to the compressor 30.

[0026] During heating operation, the process is reversed compared to cooling operation. The indoor heat exchanger 20 is used as a condenser and the outdoor heat exchanger 34 is used as an evaporator. The refrigerant sealed in the system is circulated in the following order: compressor 30, four-way valve 32, indoor heat exchanger 20, outdoor expansion valve 33, outdoor heat exchanger 34, four-way valve 32, accumulator 31, and compressor 30.

[0027] During heating operation, the outdoor heat exchanger 34 of the air conditioning system 10 functions as an evaporator, absorbing heat from the outside air. As a result, water vapor in the outside air crystallizes on the surface of the outdoor heat exchanger 34 and adheres as frost. When frost adheres to the outdoor heat exchanger 34, it becomes unable to absorb heat from the outside air. Therefore, the air conditioning system 10 has a defrosting function to remove the accumulated frost. The air conditioning system 10 performs a defrosting operation by selecting the defrosting function, and melts and removes the frost attached to the fins of the outdoor heat exchanger 34 using the waste heat from the compressor 30 or the like. The removal of frost is not limited to using the waste heat from the compressor 30; it may also be removed by methods such as spraying hot water.

[0028] The compressor 30 and the four-way valve 32, the four-way valve 32 and the indoor heat exchanger 20, the indoor heat exchanger 20 and the outdoor expansion valve 33, the outdoor expansion valve 33 and the outdoor heat exchanger 34, the outdoor heat exchanger 34 and the four-way valve 32, the four-way valve 32 and the accumulator 31, and the accumulator 31 and the compressor 30 are each connected by refrigerant piping.

[0029] Copper piping is used for refrigerant piping, considering its thermal conductivity, workability, and corrosion resistance. The copper piping is phosphorus-deoxidized copper piping, which contains a small amount of phosphorus (P). Phosphorus-deoxidized copper is pure copper with a copper (Cu) content of 99.9% or more, and by deoxidizing with P, it is a material that does not suffer from hydrogen embrittlement even when exposed to high temperatures in a reducing atmosphere. Hereafter, when simply written as "%", it means "mass%". Hydrogen embrittlement is a phenomenon in which the strength and toughness of Cu are reduced due to hydrogen absorbed by Cu. Phosphorus-deoxidized copper generally contains 0.015 to 0.04% P. In addition to refrigerant piping, phosphorus-deoxidized copper is also used as heat transfer tubes for indoor heat exchangers 20 and outdoor heat exchangers 34. Oxygen-free copper piping may be used instead of phosphorus-deoxidized copper piping.

[0030] Figure 2 is a detailed diagram showing the configuration around the outdoor heat exchanger 34 that constitutes the outdoor unit 12. The outdoor heat exchanger 34 has a plurality of heat transfer tubes 40, and one end of each heat transfer tube 40 is connected to each of the plurality of branch tubes 43 that branch off from the main tube 42 which constitutes the gas header 41 as a branch tube, to the tube connected to one end of the main tube 42, and to the tube connected to the other end of the main tube 42. A connecting tube 45 is connected to the main tube 42 and the refrigerant piping 44 which is connected to the four-way valve 32. The other end of each heat transfer tube 40 is connected to each connecting tube 46 of the liquid header 47, which serves as a liquid collector equipped with a plurality of connecting tubes 46. The liquid header 47 is connected to the outdoor expansion valve 33 by refrigerant piping.

[0031] The air conditioning system 10, including the outdoor heat exchanger 34, uses copper materials in the heat transfer tubes 40, gas header 41, refrigerant piping 44, and liquid header 47, even just around the outdoor heat exchanger 34. Thus, the air conditioning system 10 uses a lot of copper, but the recent surge in copper prices has increased its manufacturing costs and is putting pressure on profits. For this reason, the use of other materials instead of copper is being considered, and one example of this is to use stainless steel pipes for the main pipes of the branch pipes (gas header 41), as described in the above-mentioned Patent Document 2.

[0032] When replacing the main pipe 42 of the gas header 41 with stainless steel piping, it is necessary to braze the stainless steel pipe of the main pipe 42 with the phosphorus-deoxidized copper pipe (hereinafter simply referred to as copper pipe) of the branch pipe 43. Brazing is a method of joining metals using a brazing material. Examples of brazing materials include silver brazing, copper brazing, copper alloy brazing, nickel brazing, gold brazing, and palladium brazing.

[0033] Stainless steel is a material that contains 1.2% or less carbon (C), 10.5% or more chromium (Cr), and the total amount of alloying elements other than iron (Fe) does not exceed 50%. It has excellent corrosion resistance due to the chromium oxide film (passivation film) formed on its surface.

[0034] Brazing dissimilar metals like stainless steel and copper in the open air is undesirable for mass production in terms of quality and labor costs. This is because the passive film on the surface of stainless steel hinders the flow of the brazing material, requiring the use of flux to remove the passive film, brazing material with a high silver content, and proper control of heating time and location. For this reason, in mass production, furnace brazing in an oxygen-free environment is generally used instead of brazing dissimilar metals in the open air. By using a subassembly in which copper pipes have been pre-brazed to stainless steel pipes, the gas header 41 and the heat transfer tubes 40 of the outdoor heat exchanger 34 can be connected by brazing copper pipes together as in the conventional method.

[0035] However, in furnace brazing of stainless steel and copper pipes, as mentioned above, prolonged exposure to high temperatures of around 800-1200°C inside the furnace causes the copper pipe portion to undergo crystal coarsening, resulting in a significant decrease in tensile strength and fatigue strength.

[0036] The main pipe 42 of the gas header 41 expands and contracts due to rapid changes in refrigerant temperature, such as during defrosting operation of the air conditioning unit 10 or when starting heating in a low-temperature environment. If the main pipe 42 of the gas header 41 and the heat transfer tubes 40 of the outdoor heat exchanger 34 are made of dissimilar metals, the amount of expansion and contraction will differ, and this difference can cause significant stress in the branch pipes 43 connecting the main pipe 42 and the heat transfer tubes 40. If the branch pipes 43 cannot withstand this stress, they will break.

[0037] Therefore, after diligent research by the inventors of the present invention, they found that when replacing copper pipes with iron, iron alloy, or stainless steel pipes, the pipe brazed in the furnace to the replacement pipes should not be a copper pipe, but rather a copper alloy pipe containing one or more alloying elements selected from, for example, Co, Sn, Zn, Ni, Zr, and Fe, thereby suppressing the reduction in strength during furnace brazing.

[0038] This is thought to be because adding foreign components such as Co, Sn, Zn, Ni, Zr, and Fe to Cu causes solid solution strengthening and precipitation hardening. Solid solution strengthening is an improvement in strength by inhibiting dislocation movement due to the presence of foreign components, making it less prone to deformation. Precipitation hardening is an improvement in strength by inhibiting dislocation movement and making it less prone to deformation by precipitating compounds of foreign components. In addition, it is thought that adding foreign components has the effect of suppressing crystal coarsening.

[0039] Figure 3 shows an example of the configuration of a branch pipe (gas header). Figure 3(a) is a view from any direction, and Figure 3(b) is a view with the main pipe 42 rotated 90° in its circumferential direction.

[0040] The gas header 41 includes a main pipe 42, a number of branch pipes 43 that branch off from the main pipe 42 and connect the main pipe 42 to each heat transfer tube 40 of the outdoor heat exchanger 34, and a connecting pipe 45 that connects the other end of the main pipe 42 to the refrigerant piping 44 connected to the four-way valve 32.

[0041] The main pipe 42 has a larger diameter than the branch pipes 43 in order to distribute the refrigerant gas to each branch pipe 43 and to merge the refrigerant gas from each branch pipe 43. In order to reduce material costs, it is appropriate to replace the material of this large-diameter pipe with a cheaper material. Therefore, the main pipe 42 is made of iron, iron alloy, or stainless steel, which are cheaper than copper pipes.

[0042] Iron may be pure iron, or it may be carbon steel containing carbon (C), manganese (Mn), phosphorus (P), and sulfur (S). According to JIS G 0203:2009 (Steel Terminology (Products and Quality)), pure iron is iron with a carbon content of 0.02% or less, and carbon steel is steel with a carbon content in the range of 0.02% to approximately 2%.

[0043] Iron alloys are materials made by adding one or more alloying elements to iron. Examples of alloying elements include aluminum (Al), boron (B), Cr, Co, Cu, lead (Pb), Mn, molybdenum (Mo), Ni, niobium (Nb), silicon (Si), titanium (Ti), tungsten (W), vanadium (V), and Zr.

[0044] Iron alloys generally contain about 1-50% of the above-mentioned alloying elements in carbon steel. Stainless steel, as mentioned above, contains 10.5% or more Cr.

[0045] The heat transfer tubes 40 and refrigerant piping 44 of the outdoor heat exchanger 34 are made of copper. Therefore, copper alloy piping (copper alloy pipes) is used for the branch pipes 43 and connecting pipes 45 that connect the copper heat transfer tubes 40 and refrigerant piping 44 to the main pipe 42. However, copper alloy pipes may be used for only some of the branch pipes 43. For example, copper pipes may be used instead of copper alloy pipes for the central branch pipe 43, where the effects of expansion and contraction of the main pipe 42 are minimal.

[0046] (Examples) The bending fatigue of the piping in two embodiments and two comparative examples for comparison with those two embodiments was measured using the bending fatigue test method specified in JIS Z 2273. Figure 4 is an S / N diagram showing the results of the bending fatigue test. The S / N diagram in Figure 4 shows the number of cycles N required to break the piping under a predetermined repeated stress S applied to it.

[0047] The piping in Example 1 is formed from a copper alloy with material number C5010T-O and heated to a temperature equivalent to that of furnace brazing. C5010T-O is a copper alloy having a composition of 99.2% or more Cu, 0.58-0.72% Sn, and 0.015-0.040% P. This piping is heated, for example, in a furnace at a furnace temperature of 1000-1100°C for 20-30 minutes.

[0048] The piping in Example 2 was formed from a copper alloy with material number C1862T-O and heated under the same conditions as in Example 1. C1862T-O is a copper alloy having a composition of 99.4% or more Cu, 0.07-0.12% Sn, 0.02-0.10% Zn, 0.02-0.06% Ni, 0.046-0.062% P, and 0.16-0.21% Co.

[0049] The piping in Comparative Example 1 is made of standard copper with material number C1220T-O. C1220T-O is copper with a composition of 99.9% or more Cu and 0.015-0.040% P. The piping in Comparative Example 2 is made of standard copper with material number C1220T-O and heated under the same conditions as in Examples 1 and 2. The outer diameter, wall thickness, and length of the piping in Examples 1 and 2 and Comparative Examples 1 and 2 are all the same.

[0050] As shown in Figure 4, the piping in Examples 1 and 2 has a repeat count of 1.0 × 10 n Even in the case of (n is an integer greater than or equal to 2), the strength is higher than the allowable stress σ1. Therefore, it was found that the pipes in Examples 1 and 2 do not have any strength problems even when heated by furnace brazing.

[0051] Furthermore, it was found that the piping in Examples 1 and 2 showed less decrease in strength with increasing number of repetitions compared to the piping in Comparative Examples 1 and 2. In addition, the number of repetitions was 1.0 × 10⁻⁶. n In this test, it was found that the strength of the piping in Example 1 was close to the strength of the piping in Comparative Example 1, which was not heated.

[0052] From the above, while conventional standard copper pipes experience a significant decrease in strength upon heating, using copper alloy pipes ensures that the strength remains equivalent to or even better than that of standard copper pipes before heating, even after heating. This solves the problem of reduced strength in the accompanying copper pipes, which is a concern when replacing some copper pipes with stainless steel pipes, and makes replacement of copper pipes easier. As a result, significant cost reductions can be achieved.

[0053] The main body of the liquid header 47 of the outdoor heat exchanger 34 may also be made of iron, an iron alloy, or stainless steel, similar to the main pipe 42 of the gas header 41, and the connecting pipe 46 may be made of copper alloy. However, the liquid header 47, which contains the liquid, does not need to have a larger volume than the gas header 41, and even if the refrigerant temperature changes rapidly, the amount of expansion and contraction is small because the refrigerant contained inside is a liquid, so there is little benefit in replacing it with inexpensive stainless steel or the like. For this reason, the liquid header 47 can remain made of copper as before, and only the main pipe 42 of the gas header 41 can be replaced with inexpensive stainless steel or the like.

[0054] Furthermore, the configuration around the indoor heat exchanger 20 is the same as that around the outdoor heat exchanger 34, and since the heat transfer tubes of the indoor heat exchanger 20 are made of copper, the main pipe of the gas header can be made of stainless steel or the like, and the branch pipes can be made of copper alloy. In this case as well, the main body of the liquid header can be made of stainless steel or the like, and the connecting pipes can be made of copper alloy, or the liquid header can be made of copper as before.

[0055] The copper pipe is not limited to piping made of phosphorus-deoxidized copper, but may also be made of copper. Therefore, the copper pipe is either pure copper piping that does not contain alloying elements, or copper piping that contains 0.015 to 0.040% P as an alloying element. On the other hand, copper alloy pipes contain the same amount or more P as copper pipes, and in addition to P, they also contain alloying elements such as Sn. For this reason, the heat transfer tube 40 using copper pipe has a lower alloying element content than the branch pipe 43 using copper alloy pipe.

[0056] Furthermore, the branch pipe 43 does not have to be entirely made of copper alloy; the side that connects to the main pipe 42 may be made of stainless steel or the like, and the side that connects to the heat transfer tube 40 may be made of copper alloy. In other words, the stainless steel or the like piping will be placed between the main pipe 42 and the copper alloy piping. In this case, the stainless steel piping and the copper alloy piping of the branch pipe 43 will be brazed in the furnace.

[0057] Iron alloys and stainless steel contain 1% or more alloying elements, but copper alloys contain less than 1% alloying elements because copper exceeds 99.0%. Therefore, the copper alloy pipe used for the branch pipe 43 has a lower alloying element content than the iron alloy or stainless steel pipe used for the main pipe 42.

[0058] Although the outdoor unit and refrigeration cycle device of the present invention have been described in detail using the embodiments described above, the present invention is not limited to the embodiments described above. Other embodiments, additions, modifications, and deletions can be made within the scope that a person skilled in the art can conceive, and any embodiment that achieves the operation and effects of the present invention is included within the scope of the present invention.

[0059] Therefore, according to the present invention, (1) an outdoor unit provided for a refrigeration cycle device, An outdoor unit can be provided that includes a heat exchanger having copper heat transfer tubes, a main pipe made of iron, an iron alloy, or stainless steel, and a branch pipe comprising branch pipes that branch off from the main pipe and are connected to the heat transfer tubes, wherein at least a portion of the branch pipe has copper alloy piping containing one or more alloying elements selected from cobalt, tin, zinc, nickel, zirconium, and iron.

[0060] According to the present invention, (2) the outdoor unit described in (1) above can be provided, wherein the heat transfer tube does not contain the alloying element, or the content of the alloying element is lower than that of the branch tube.

[0061] According to the present invention, (3) an outdoor unit for a refrigeration cycle device can be provided, comprising a heat exchanger having copper heat transfer tubes, a main pipe made of iron, an iron alloy, or stainless steel, and a branch pipe comprising branch pipes that branch off from the main pipe and are connected to the heat transfer tubes, wherein at least a portion of the branch pipe has copper alloy piping containing one or more alloying elements selected from phosphorus, cobalt, tin, zinc, nickel, zirconium, and iron, and the heat transfer tubes do not contain the alloying elements, or the content of the alloying elements is lower than that of the branch pipes.

[0062] According to the present invention, (4) the branch pipe includes piping made of iron, iron alloy, or stainless steel, and the piping made of iron, iron alloy, or stainless steel is arranged between the main pipe and the copper alloy piping, thereby providing an outdoor unit as described in any of (1) to (3) above.

[0063] According to the present invention, (5) the content of the alloying element in the copper alloy piping is lower than the content of the alloying element in the main pipe, and an outdoor unit according to any of (1) to (4) above can be provided.

[0064] Furthermore, according to the present invention, it is possible to provide a refrigeration cycle device equipped with an outdoor unit as described in any of (1) to (5) above. [Explanation of symbols]

[0065] 10…Air conditioning system 11...Indoor unit 12...Outdoor unit 20…Indoor heat exchanger 21…Indoor fan 22... Indoor fan motor 30... Compressor 31... Accumulator 32... Four-way valve 33... Outdoor expansion valve 34…Outdoor heat exchanger 35…Outdoor fan 36... Outdoor fan motor 37...Control device 40… Heat transfer tubes 41... Gas Header 42…Superintendent 43…Branch pipe 44… Refrigerant piping 45…Connecting pipe 46…Connecting pipe 47... Liquid Header

Claims

1. An outdoor unit of a refrigeration cycle system, A heat exchanger having copper heat transfer tubes, A branch pipe consisting of a main pipe made of iron, iron alloy, or stainless steel, and branch pipes that branch off from the main pipe and are connected to the heat transfer pipes. Includes, An outdoor unit having piping made of a copper alloy containing one or more alloying elements selected from cobalt, tin, zinc, nickel, zirconium, and iron, in at least a portion of the branch pipes.

2. The outdoor unit according to claim 1, wherein the heat transfer tube does not contain the alloying element, or the content of the alloying element is lower than that of the branch tube.

3. An outdoor unit of a refrigeration cycle system, A heat exchanger having copper heat transfer tubes, A branch pipe consisting of a main pipe made of iron, iron alloy, or stainless steel, and branch pipes that branch off from the main pipe and are connected to the heat transfer pipes. Includes, At least a portion of the branch pipe has piping made of a copper alloy containing one or more alloying elements selected from phosphorus, cobalt, tin, zinc, nickel, zirconium, and iron. The heat transfer tube is an outdoor unit in which the heat transfer tube does not contain the alloying element, or the content of the alloying element is lower than that of the branch tube.

4. The aforementioned branch pipes include piping made of iron, iron alloy, or stainless steel. The outdoor unit according to claim 1 or 3, wherein the iron, iron alloy, or stainless steel piping is arranged between the main pipe and the copper alloy piping.

5. The outdoor unit according to claim 1 or 3, wherein the content of the alloying element in the copper alloy piping is lower than the content of the alloying element in the main pipe.

6. A refrigeration cycle system equipped with an outdoor unit, The aforementioned outdoor unit, A heat exchanger having copper heat transfer tubes, A branch pipe consisting of a main pipe made of iron, iron alloy, or stainless steel, and branch pipes that branch off from the main pipe and are connected to the heat transfer pipes. Includes, A refrigeration cycle device in which at least a portion of the branch pipes has piping made of a copper alloy containing one or more alloying elements selected from cobalt, tin, zinc, nickel, zirconium, and iron.

7. A refrigeration cycle system equipped with an outdoor unit, The aforementioned outdoor unit, A heat exchanger having copper heat transfer tubes, A branch pipe consisting of a main pipe made of iron, iron alloy, or stainless steel, and branch pipes that branch off from the main pipe and are connected to the heat transfer pipes. Includes, At least a portion of the branch pipe has piping made of a copper alloy containing one or more alloying elements selected from phosphorus, cobalt, tin, zinc, nickel, zirconium, and iron. A refrigeration cycle device in which the heat transfer tube does not contain the alloying element, or the content of the alloying element is lower than that of the branch tube.

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