Outdoor unit and refrigeration cycle device

Abstract

The invention provides an outdoor unit and a refrigeration cycle device which are provided with a branch pipe capable of suppressing reduction of strength even when brazed in a furnace. An outdoor unit provided in a refrigeration cycle device is provided with: an outdoor heat exchanger (34) having a copper heat transfer tube; and a branch pipe (41) comprising a main pipe (42) made of iron, iron alloy, or stainless steel, and a branch pipe (43) branched from the main pipe (42) and connected to the heat transfer pipe (40), at least a portion of the branch pipe (43) having copper alloy piping containing one or more alloy elements selected from cobalt, tin, zinc, nickel, zirconium, and iron.

Description

Technical Field

[0001] This invention relates to an outdoor unit and a refrigeration cycle device. Background Technology

[0002] In recent years, the demand for copper has increased due to the widespread use of electronic devices, leading to a surge in copper prices. Copper's excellent thermal conductivity, machinability, and corrosion resistance make it suitable for refrigerant piping in refrigeration systems such as air conditioners. However, the high price reduces profitability, prompting research into alternative materials to replace copper.

[0003] For example, as a heat transfer tube for a heat exchanger used in an air conditioner, it is proposed to use a copper alloy tube containing cobalt (Co), tin (Sn), zinc (Zn), nickel (Ni), and phosphorus (P), and to make the main manifold of the gas collection tube connected to the copper tube group that is the heat transfer tube of the air conditioner system stainless steel (for example, see Patent Documents 1 and 2).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 5111922

[0007] Patent Document 2: Japanese Patent Publication No. 2024-515018 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] As described in Patent Document 2 above, when the main manifold (main pipe) of the gas collection pipe (branch pipe) connected to the heat exchanger is made of stainless steel pipe, and the sub-assemblies consisting of branch pipes branching from the main pipe and pipes connected to the front end of the main pipe are manufactured by brazing in a furnace, the copper pipe portion coarsens due to prolonged exposure to a high temperature environment of about 800 to 1200°C in the furnace, and the tensile strength and fatigue strength are significantly reduced.

[0010] During defrosting operation or startup of heating operation in low-temperature environments, the main pipe expands or contracts when the refrigerant temperature changes rapidly. At this time, a difference in the amount of expansion or contraction occurs between the main pipe and the branch pipe, sometimes generating greater stress on the branch pipe.

[0011] Therefore, when copper tubes whose strength has been reduced due to brazing in the furnace are used as branch pipes, there is a high possibility that they will break due to their inability to withstand the stress caused by the expansion or contraction mentioned above.

[0012] Therefore, it is desirable to provide an outdoor unit and a refrigeration cycle device with branch pipes that can suppress strength reduction even when brazing in a furnace.

[0013] Methods for solving problems

[0014] In view of the above-mentioned problems, the present invention provides an outdoor unit, which is an outdoor unit of a refrigeration cycle device, characterized in that it comprises: a heat exchanger having a copper heat transfer tube; and a branch pipe consisting of a main pipe made of iron, iron alloy, or stainless steel and a branch pipe branching from the main pipe and connected to the heat transfer tube, wherein at least a portion of the branch pipe has a copper alloy piping containing one or more alloying elements selected from cobalt, tin, zinc, nickel, zirconium, and iron.

[0015] Additionally, a refrigeration cycle device is provided, comprising an outdoor unit, characterized in that the outdoor unit includes: a heat exchanger having a copper heat transfer tube; and a branch pipe consisting of a main pipe made of iron, iron alloy, or stainless steel, and branch pipes branching from the main pipe and connected to the heat transfer tube, 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.

[0016] Invention Effects

[0017] According to the present invention, it is possible to provide an outdoor unit and a refrigeration cycle device having branch pipes that can suppress strength reduction even when brazing in a furnace. Attached Figure Description

[0018] Figure 1 This is a diagram showing a structural example of an air conditioning unit as an example of a refrigeration cycle device.

[0019] Figure 2 This is a diagram showing in detail the structure surrounding the outdoor heat exchanger that constitutes the outdoor unit.

[0020] Figure 3 This is a diagram showing an example of the structure of a branch pipe.

[0021] Figure 4 This is an SN graph showing the results of a bending fatigue test.

[0022] Symbol Explanation

[0023] 10…Air conditioning unit; 11…Indoor unit; 12…Outdoor unit; 20…Indoor heat exchanger; 21…Indoor fan; 22…Indoor fan motor; 30…Compressor; 31…Receiver; 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 pipe; 41…Gas manifold; 42…Main pipe; 43…Branch pipe; 44…Refrigerant piping; 45…Connecting pipe; 46…Connecting pipe; 47…Liquid manifold. Detailed Implementation

[0024] A refrigeration cycle device is a device that continuously cools or heats a fluid by circulating the refrigerant within a system while changing the pressure and state of the refrigerant, which serves as a heat transfer medium, and by exchanging heat with the circulating refrigerant. Examples include refrigeration machines and air conditioning units. Hereinafter, the refrigeration cycle device will be described as an air conditioning unit, but it is not limited to air conditioning units.

[0025] Figure 1 This diagram illustrates a structural example of an air conditioning unit. The air conditioning unit 10 includes: an indoor unit 11, which is an indoor unit installed in a space where air conditioning is performed (indoor); an outdoor unit 12, which is an outdoor unit installed outdoors; and a controller operated by a user. The air conditioning unit 10 performs air conditioning by circulating refrigerant between the indoor unit 11 and the outdoor unit 12 and exchanging heat with the fluid that is being cooled or heated, i.e., the indoor air. Therefore, the indoor unit 11 and the outdoor unit 12 are connected by refrigerant piping to facilitate refrigerant circulation.

[0026] The indoor unit 11 and outdoor unit 12 can each consist of two or more units, or two or more indoor units 11 can be connected to one outdoor unit 12. Hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs) can be used as refrigerants. Examples of HFCs include R410A and R32. Examples of HFOs include R1234yf.

[0027] The indoor unit 11 communicates with the controller, receiving various signals such as operation commands, stop commands, set temperature change commands, and operation mode change commands. The indoor unit 11 and the controller can be connected via cable for wired communication, or wirelessly via infrared or other means. The indoor unit 11 is connected to the outdoor unit 12 via a communication line, and together they perform indoor air conditioning.

[0028] The indoor unit 11 starts upon receiving an operation command from the controller, and instructs the outdoor unit 12 to start. After starting, the outdoor unit 12 adjusts the compressor speed, the opening of the outdoor expansion valve, and controls the refrigerant circulation to bring the indoor temperature to the set temperature.

[0029] The indoor unit 11 includes an indoor heat exchanger 20, an indoor fan 21, and an indoor fan motor 22 as a power source. The indoor fan 21, driven by the indoor fan motor 22, draws in indoor air and delivers it to the indoor heat exchanger 20. The indoor heat exchanger 20 is configured with heat transfer tubes through which refrigerant flows, and the delivered air exchanges heat with the surface of the heat transfer tubes. The air that has undergone heat exchange through the indoor heat exchanger 20 is then discharged into the room.

[0030] In addition, the indoor unit 11 can also be equipped with various sensors for measuring indoor temperature, indoor expansion valves, etc.

[0031] The outdoor unit 12 includes a compressor 30, a liquid receiver 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 the power source. The compressor 30, driven by the compressor motor, compresses low-pressure gaseous refrigerant and discharges it as high-pressure gaseous refrigerant. The liquid receiver 31 separates the gas and liquid, preventing liquid from entering the compressor 30.

[0032] The four-way valve 32 is a valve that switches the refrigerant flow path according to the operating state (operating mode) of the air conditioning unit 10. Operating modes include cooling mode, heating mode, and fan-only mode. The outdoor expansion valve 33 is a valve that adjusts the refrigerant pressure and flow rate by expanding the high-pressure refrigerant. The outdoor fan 35, driven by the outdoor fan motor 36, draws in outdoor air and sends it to the outdoor heat exchanger 34. Similar to the indoor heat exchanger 20, the outdoor heat exchanger 34 is also configured with heat transfer tubes through which refrigerant flows, and the incoming air contacts the surface of the heat transfer tubes for heat exchange. The air that has undergone heat exchange through the outdoor heat exchanger 34 is discharged outdoors.

[0033] The outdoor unit 12 also includes a control device 37. The control device 37 is connected to and controls the compressor 30, four-way valve 32, outdoor expansion valve 33, indoor fan motor 22, and outdoor fan motor 36. Specifically, it controls the speed of the compressor motor, the opening degree of the outdoor expansion valve 33, and the speeds of the indoor fan motor 22 and outdoor fan motor 36. Various sensors are also installed on the outdoor unit 12 to control these components. The control device 37 performs these controls based on information detected by these sensors. It should be noted that the control device 37 is not limited to the outdoor unit 12; it can also be installed in the indoor unit 11, or its functions can be divided into two separate units, one in the indoor unit 11 and one in the outdoor unit 12. Alternatively, it can be an independent device located in a different location from the indoor unit 11 and outdoor unit 12, rather than being installed inside the indoor unit 11 or outdoor unit 12.

[0034] During refrigeration operation, the indoor heat exchanger 20 is used as an evaporator, and the outdoor heat exchanger 34 is used as a condenser. Therefore, as indicated by the arrow, the control device 37 causes the refrigerant sealed in the system to circulate in the following order: compressor 30, four-way valve 32, outdoor heat exchanger 34, outdoor expansion valve 33, indoor heat exchanger 20, four-way valve 32, receiver 31, and compressor 30.

[0035] 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. Outdoor heat exchanger 34 exchanges heat with outdoor air, causing the refrigerant gas to cool and condense. Outdoor expansion valve 33 expands the refrigerant, adjusting the pressure of the refrigerant flowing in the evaporator and regulating the refrigerant flow rate to maintain a constant superheat at the evaporator outlet. Superheat indicates how many degrees higher than the saturation temperature; it is an indicator of the degree of superheat.

[0036] The indoor heat exchanger 20 exchanges heat with the indoor air, causing the refrigerant gas heated to the aforementioned superheated state to return to the outdoor unit 12. The refrigerant gas returning from the indoor heat exchanger 20 is sent to the receiver 31 through the four-way valve 32 and then back to the compressor 30.

[0037] In contrast to the cooling operation, during the heating operation, the indoor heat exchanger 20 is used as a condenser and the outdoor heat exchanger 34 is used as an evaporator, so that the refrigerant sealed in the system circulates 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, receiver 31, and compressor 30.

[0038] In the air conditioning unit 10, during heating operation, the outdoor heat exchanger 34 functions as an evaporator, drawing heat from the outside air. Consequently, water vapor in the outside air crystallizes on the surface of the outdoor heat exchanger 34, forming frost. When frost adheres to the outdoor heat exchanger 34, it cannot draw heat from the outside air. Therefore, the air conditioning unit 10 has a defrosting function to remove the frost. The air conditioning unit 10 performs defrosting operation by selecting the defrosting function, using the heat dissipation of the compressor 30 to melt and remove the frost adhering to the fins of the outdoor heat exchanger 34. Frost removal is not limited to using the heat dissipation of the compressor 30; it can also be achieved by spraying warm water.

[0039] The compressor 30 is connected to the four-way valve 32, the four-way valve 32 is connected to the indoor heat exchanger 20, the indoor heat exchanger 20 is connected to the outdoor expansion valve 33, the outdoor expansion valve 33 is connected to the outdoor heat exchanger 34, the outdoor heat exchanger 34 is connected to the four-way valve 32, the four-way valve 32 is connected to the liquid receiver 31, and the liquid receiver 31 is connected to the compressor 30 via refrigerant piping.

[0040] Considering thermal conductivity, processability, and corrosion resistance, copper piping is used for refrigerant piping. This copper piping is made of phosphorus-deoxidized copper containing trace amounts of phosphorus (P). Phosphorus-deoxidized copper is pure copper (Cu) with a purity of 99.9% or higher. It is deoxidized using P, thus preventing hydrogen embrittlement even at high temperatures in a reducing atmosphere. Hereinafter, when listed as "%", it refers to "mass %". Hydrogen embrittlement is the phenomenon where the strength and toughness of Cu decrease due to the absorption of hydrogen by Cu. Phosphorus-deoxidized copper typically contains 0.015–0.04% P. Besides being used for refrigerant piping, phosphorus-deoxidized copper is also used for heat transfer tubes in indoor heat exchangers 20 and outdoor heat exchangers 34. Oxygen-free copper piping can also be used instead of phosphorus-deoxidized copper piping.

[0041] Figure 2 This diagram shows in detail the structure surrounding the outdoor heat exchanger 34 that constitutes the outdoor unit 12. The outdoor heat exchanger 34 has multiple heat transfer tubes 40. One end of each heat transfer tube 40 is connected to each of multiple branch pipes 43 branching from the main pipe 42, which constitutes a branch pipe of the gas manifold 41, to one end of the main pipe 42, and to the other end of the main pipe 42. At the other end of the main pipe 42 of the gas manifold 41, a connecting pipe 45 connects a refrigerant pipe 44 connected to the four-way valve 32 and the main pipe 42. The other end of each heat transfer tube 40 serves as a liquid collector equipped with multiple connecting pipes 46 and is connected to each connecting pipe 46 of a liquid manifold 47. The liquid manifold 47 is connected to the outdoor expansion valve 33 via a refrigerant pipe.

[0042] In the air conditioning unit 10, copper is used in the heat transfer pipe 40, gas manifold 41, refrigerant piping 44, and liquid manifold 47, including the outdoor heat exchanger 34, and even just around the outdoor heat exchanger 34. Thus, the air conditioning unit 10 uses a large amount of copper, but the high price of copper in recent years has increased its manufacturing costs and reduced profits. Therefore, the use of other materials to replace copper has been studied. As one example, as described in the aforementioned Patent Document 2, there are cases where the main pipe of the branch pipe (gas manifold 41) is made of stainless steel.

[0043] When the main pipe 42 of the gas manifold 41 is replaced with a stainless steel pipe, it is necessary to braze the stainless steel pipe of the main pipe 42 and the phosphorus-deoxidized copper pipe (hereinafter referred to as copper pipe) of the branch pipe 43. Brazing is a method of joining metals using brazing filler metal. Examples of brazing filler metals include silver brazing filler metal, copper brazing filler metal, copper alloy brazing filler metal, nickel brazing filler metal, gold brazing filler metal, palladium brazing filler metal, etc.

[0044] Stainless steel is a material containing less than 1.2% carbon (C), more than 10.5% chromium (Cr), and the total amount of alloying elements other than iron (Fe) does not exceed 50%. It has excellent corrosion resistance through the Cr oxide film (passivation film) formed on the surface.

[0045] In terms of quality and operating time, mass production is not preferred when brazing dissimilar metals such as stainless steel and copper tubes in the atmosphere. This is because the passivation film on the surface of stainless steel hinders the flow of brazing filler metal. Therefore, fluxes that remove the passivation film and brazing filler metals with high silver content must be used, and heating time and position must be properly managed. Therefore, in mass production, dissimilar metal brazing is generally not performed in the atmosphere, but rather in an oxygen-free furnace environment. By using sub-assemblies obtained by pre-brazing copper tubes to stainless steel tubes in the furnace, the gas manifold 41 can be connected to the heat transfer tubes 40 of the outdoor heat exchanger 34 by brazing copper tubes to each other, as has been done in the past.

[0046] However, as mentioned above, in the furnace brazing of stainless steel tubes and copper tubes, due to prolonged exposure to the high temperature environment of about 800 to 1200°C in the furnace, the crystals of the copper tube become coarser, and the tensile strength and fatigue strength are significantly reduced.

[0047] During defrosting operation of the air conditioning unit 10, or during heating startup in low-temperature environments, the main pipe 42 of the gas manifold 41 expands or contracts due to rapid changes in refrigerant temperature. When the main pipe 42 of the gas manifold 41 and the heat transfer pipe 40 of the outdoor heat exchanger 34 are made of different types of metal, the expansion and contraction amounts differ. Sometimes, this difference generates significant stress in the branch pipe 43 connecting the main pipe 42 and the heat transfer pipe 40. If this stress cannot be withstood, the branch pipe 43 may break.

[0048] Therefore, the inventors of this invention conducted in-depth research and found that when copper pipes are replaced with iron, ferroalloy, or stainless steel pipes, the pipes used for furnace brazing in the replaced pipes are not copper pipes, but rather copper alloy pipes, for example, containing one or more alloying elements selected from Co, Sn, Zn, Ni, Zr, and Fe, thereby suppressing the reduction in strength during furnace brazing.

[0049] This is believed to be because the addition of different components such as Co, Sn, Zn, Ni, Zr, and Fe to Cu leads to solid solution strengthening and precipitation hardening. Solid solution strengthening is due to the presence of these different components hindering dislocation movement and making the material difficult to deform, thus increasing strength. Precipitation hardening is achieved by precipitating compounds of different components, which also hinder dislocation movement and make the material difficult to deform, thereby increasing strength. Furthermore, it is believed that adding different components has the effect of suppressing coarsening of the crystals.

[0050] Figure 3 This is a diagram showing an example of the structure of a branch pipe (gas manifold). Figure 3 (a) is a diagram observed from any direction. Figure 3 (b) is a diagram after the main tube 42 is rotated 90° around its circumference.

[0051] The gas manifold 41 includes: a main pipe 42; a plurality of branch pipes 43 branching from the main pipe 42 and connecting the main pipe 42 and each heat transfer pipe 40 of the outdoor heat exchanger 34; and a connecting pipe 45 connecting the other end of the main pipe 42 and the refrigerant piping 44 connected to the four-way valve 32.

[0052] The main pipe 42 distributes refrigerant gas to each branch pipe 43, and also merges the refrigerant gas from each branch pipe 43; therefore, its diameter is larger than that of the branch pipes 43. To reduce material costs, it is appropriate to replace the material of this larger diameter pipe with a cheaper material. Therefore, the main pipe 42 uses iron, iron alloy, or stainless steel piping, which is cheaper than copper piping.

[0053] Iron can be pure iron or carbon steel containing carbon (C), manganese (Mn), phosphorus (P), and sulfur (S). In JIS G0203:2009 (Iron Terminology (Products and Quality)), pure iron is iron with a carbon content of less than 0.02%, and carbon steel is steel with a carbon content ranging from 0.02% to about 2%.

[0054] Ferroalloys are materials in which one or more alloying elements are added to iron. These 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.

[0055] Ferroalloys typically contain about 1% to 50% of the aforementioned alloying elements in carbon steel. As mentioned above, stainless steel contains more than 10.5% Cr.

[0056] The heat transfer pipes 40 and refrigerant piping 44 of the outdoor heat exchanger 34 are made of copper. Therefore, the branch pipes 43 and connecting pipes 45 that connect the copper heat transfer pipes 40 and refrigerant piping 44 to the main pipe 42 are made of copper alloy pipes. It should be noted that only a portion of the multiple branch pipes 43 may be made of copper alloy pipes. For example, the central branch pipe 43, which is less affected by the expansion and contraction of the main pipe 42, may be made of copper pipe instead of copper alloy pipe.

[0057] (Example)

[0058] For the piping in the two embodiments and the two comparative examples used for comparison with the two embodiments, bending fatigue was determined by the bending fatigue test method specified in JIS Z2273. Figure 4 This is an SN graph showing the results of a bending fatigue test. Figure 4 The SN diagram represents the number of repetitions N required to apply a specified cyclic stress S to the piping and to use that cyclic stress S to destroy the piping.

[0059] In Example 1, the piping was formed of a copper alloy with material number C5010T-O and was heated at the same temperature as that used for brazing in the furnace. C5010T-O is a copper alloy with a composition of 99.2% or more Cu, 0.58% to 0.72% Sn, and 0.015% to 0.040% P. The piping was heated, for example, in a furnace at a temperature of 1000 to 1100°C for 20 to 30 minutes.

[0060] In Example 2, the piping was formed of a copper alloy with material number C1862T-O and was heated under the same conditions as in Example 1. C1862T-O is a copper alloy having a composition of Cu 99.4% or more, Sn 0.07-0.12%, Zn 0.02-0.10%, Ni 0.02-0.06%, P 0.046-0.062%, and Co 0.16-0.21%.

[0061] The piping in Comparative Example 1 was formed from standard copper with material number C1220T-O. C1220T-O is copper with a composition of 99.9% or more Cu and 0.015 to 0.040% P. The piping in Comparative Example 2 was formed from standard copper with material number C1220T-O and was heated under the same conditions as in Examples 1 and 2. The outer diameter, wall thickness, and length of each piping in Examples 1 and 2 and Comparative Examples 1 and 2 were all identical.

[0062] like Figure 4 As shown, even when the number of repetitions is 1.0 × 10 n In the case where n is an integer greater than 2, the piping in Examples 1 and 2 also exceeds the allowable stress σ1. Therefore, it can be seen that the piping in Examples 1 and 2 does not have a strength problem even if it is heated by furnace brazing.

[0063] Furthermore, it can be seen that the piping in Examples 1 and 2, compared to the piping in Comparative Examples 1 and 2, exhibits a smaller decrease in strength with increasing repetition count. Therefore, it can be seen that at a repetition count of 1.0 × 10⁻⁶, the strength reduction is less. n In this case, the strength of the piping in Example 1 is close to the strength of the piping in Comparative Example 1, which was not heated.

[0064] As can be seen from the above, the strength of standard copper pipes used in the past is significantly reduced by heating. However, by using copper alloy pipes, the strength can be maintained at the same or higher level as the standard copper pipe before heating, even after heating. Therefore, the problem of reduced strength of the copper pipes, which is a concern when stainless steel pipes or similar materials are used to replace some copper pipes, can be solved, and copper pipe replacement can be easily achieved. This results in a significant cost reduction.

[0065] Similar to the main pipe 42 of the gas manifold 41, the main body of the liquid manifold 47 of the outdoor heat exchanger 34 can also be made of iron, iron alloy, or stainless steel, and the connecting pipe 46 can be made of copper alloy. However, the volume of the liquid manifold 47, which contains liquid, can be smaller than that of the gas manifold 41. Even if the refrigerant temperature changes drastically, since the refrigerant inside is liquid, the expansion and contraction are small, and the advantage of replacing it with inexpensive stainless steel is less significant. Therefore, it is possible to make the liquid manifold 47 copper as before, and only replace the main pipe 42 of the gas manifold 41 with inexpensive stainless steel.

[0066] Furthermore, the structure surrounding the indoor heat exchanger 20 is the same as that surrounding the outdoor heat exchanger 34. Since the heat transfer tubes of the indoor heat exchanger 20 are made of copper, the main pipe of the gas manifold can be made of stainless steel, and the branch pipes can be made of copper alloy. In this case, the main body of the liquid manifold can also be made of stainless steel, and the connecting pipes can be made of copper alloy, or the liquid manifold can be made of copper as before.

[0067] Copper pipes are not limited to those made of phosphorus-deoxidized copper; they can also be made of copper. Therefore, copper pipes can be pure copper without any alloying elements or copper containing 0.015 to 0.040% phosphorus (P) as an alloying element. On the other hand, copper alloy pipes contain the same or more phosphorus as copper pipes, and in addition to P, they also contain alloying elements such as sn. Therefore, compared to branch pipes 43 using copper alloy pipes, the heat transfer tubes 40 using copper pipes have a lower alloying element content.

[0068] Alternatively, regarding branch pipe 43, it is possible that not all branch pipe 43 is made of copper alloy. The side connecting to the main pipe 42 can be made of stainless steel or similar material, while the side connecting to the heat transfer pipe 40 can be made of copper alloy. That is, stainless steel or similar material is placed between the main pipe 42 and the copper alloy material. In this case, the stainless steel and copper alloy materials of the branch pipe 43 are brazed in a furnace.

[0069] Ferroalloys and stainless steel contain more than 1% alloying elements, but copper alloys contain more than 99.0% copper, so the alloying element content is less than 1%. Therefore, compared with the ferroalloy or stainless steel piping used in the main pipe 42, the copper alloy pipe used in the branch pipe 43 has a lower alloying element content.

[0070] Thus far, the outdoor unit and refrigeration cycle device of the present invention have been described in detail using the above embodiments. However, the present invention is not limited to the above embodiments and can be modified in other embodiments, additions, alterations, deletions, etc., within the scope that can be conceived by those skilled in the art. In any way, as long as it plays the role and effect of the present invention, it is included within the scope of the present invention.

[0071] Therefore, according to the present invention, (1) it is possible to provide an outdoor unit, which is an outdoor unit of a refrigeration cycle device, the outdoor unit comprising: a heat exchanger having a copper heat transfer tube; and a branch pipe consisting of a main pipe made of iron or iron alloy or stainless steel and a branch pipe branching from the main pipe and connected to the heat transfer tube, at least a portion of the branch pipe having a copper alloy piping containing one or more alloying elements selected from cobalt, tin, zinc, nickel, zirconium and iron.

[0072] According to the present invention, (2) it is possible to provide the outdoor unit described in (1) above, 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.

[0073] According to the present invention, (3) it is possible to provide an outdoor unit, which is an outdoor unit of a refrigeration cycle device, the outdoor unit comprising: a heat exchanger having a copper heat transfer tube; and a branch pipe consisting of a main pipe made of iron, iron alloy or stainless steel and a branch pipe branching from the main pipe and connected to the heat transfer tube, at least a portion of the branch pipe having a copper alloy piping containing one or more alloying elements selected from phosphorus, cobalt, tin, zinc, nickel, zirconium and iron, 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 pipe.

[0074] According to the present invention, (4) can provide an outdoor unit as described in any one of (1) to (3) above, wherein the branch pipe comprises a pipe made of iron, iron alloy or stainless steel, the pipe being disposed between the main pipe and the copper alloy pipe.

[0075] According to the present invention, (5) can provide an outdoor unit as described in any one of (1) to (4) above, wherein the content of the alloying element contained in the copper alloy piping is lower than the content of the alloying element contained in the main pipe.

[0076] In addition, according to the present invention, a refrigeration cycle device having an outdoor unit as described in any one of (1) to (5) above can be provided.

Claims

1. An outdoor unit, which is an outdoor unit of a refrigeration cycle device, characterized in that, have: A heat exchanger having copper heat transfer tubes; and The branch pipe consists of a main pipe made of iron, iron alloy, or stainless steel, and branch pipes branching from the main pipe and connected to the heat transfer pipe. At least a portion of the branch pipe has a copper alloy piping containing one or more alloying elements selected from cobalt, tin, zinc, nickel, zirconium, and iron.

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

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

4. The outdoor unit according to claim 1 or 3, characterized in that, The branch pipes include pipes made of iron, ferroalloy, or stainless steel. The iron, ferroalloy, or stainless steel piping is positioned between the main pipe and the copper alloy piping.

5. The outdoor unit according to claim 1 or 3, characterized in that, The copper alloy piping contains a lower percentage of the alloying element than the main pipe.

6. A refrigeration cycle device comprising an outdoor unit, characterized in that, The outdoor unit includes: A heat exchanger having copper heat transfer tubes; and The branch pipe consists of a main pipe made of iron, iron alloy, or stainless steel, and branch pipes branching from the main pipe and connected to the heat transfer pipe. At least a portion of the branch pipe has a copper alloy piping containing one or more alloying elements selected from cobalt, tin, zinc, nickel, zirconium, and iron.

7. A refrigeration cycle device comprising an outdoor unit, characterized in that, The outdoor unit includes: A heat exchanger having copper heat transfer tubes; and The branch pipe consists of a main pipe made of iron, iron alloy, or stainless steel, and branch pipes branching from the main pipe and connected to the heat transfer pipe. At least a portion of the branch pipe has a copper alloy conduit containing one or more alloying elements selected from phosphorus, cobalt, tin, zinc, nickel, zirconium, and iron. The heat transfer tube does not contain the alloying element, or the content of the alloying element in the heat transfer tube is lower than that in the branch tube.

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