Refrigeration cycle equipment

Abstract

To provide a refrigeration cycle system that offers high resistance to vibration in the refrigerant piping and reduces manufacturing costs. [Solution] An outdoor unit 100 of a refrigeration cycle system comprising a compressor 2, a heat source side heat exchanger 4, a pressure reducer 5a, a gas side shut-off valve 18, and a liquid side shut-off valve 19, comprising: a first metal member 11 arranged in a gas side refrigerant circuit 10A connecting the gas side shut-off valve 18 and the heat source side heat exchanger 4 via at least the compressor 2; a second metal member 12 arranged in a liquid side refrigerant circuit 10B connecting the heat source side heat exchanger 4 and the liquid side shut-off valve 19 via at least the pressure reducer 5a; a first copper pipe 13 joined to the first metal member 11; and a second copper pipe 14 joined to the second metal member 12, wherein the first metal member 11 and the second metal member 12 are made of iron, an iron alloy, or stainless steel; the first copper pipe 13 is made of a copper alloy containing alloying elements; and the second copper pipe 14 is made of copper without alloying elements, or a copper alloy with a lower alloying element content than the first copper pipe 13.

Description

Technical Field

[0001] The present invention relates to a refrigeration cycle device including a refrigerant pipe assembly in which a copper-based refrigerant pipe is joined to an iron-based refrigerant pipe made of stainless steel or the like, and particularly to an outdoor unit of a refrigeration cycle device.

Background Art

[0002] Refrigeration and air-conditioning equipment such as air conditioners, refrigerators, and freezers includes a refrigerant circuit that circulates a refrigerant to execute a refrigeration cycle. In the refrigerant circuit, devices such as a compressor, a condenser, an expansion valve, and an evaporator are connected via refrigerant pipes. Conventionally, the refrigerant pipes are made of copper such as phosphor-deoxidized copper. Also, heat transfer pipes of heat exchangers and devices such as oil separators and valves are often made of copper.

[0003] Patent Document 1 describes a copper alloy pipe for a heat exchanger that is superior in bending workability and heat resistance to conventional phosphor-deoxidized copper. In this copper alloy pipe for a heat exchanger, Co, Sn, Zn, Ni, P, etc. are positively added. In this copper alloy pipe for a heat exchanger, improvement of mechanical properties is achieved by precipitation strengthening and solid solution strengthening due to the addition of alloy elements.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, the price of copper has been rising, and the material costs of refrigerant pipes and devices forming the refrigerant circuit have been increasing. Therefore, costs can be suppressed by converting the materials of refrigerant pipes and devices forming the refrigerant circuit from copper-based materials such as phosphor-deoxidized copper to iron-based materials such as stainless steel.

[0006] However, completely switching the materials used for refrigerant piping and equipment that form the refrigerant circuit to iron-based metals presents several obstacles in terms of performance and installation. Therefore, for the time being, it is expected that conventional copper-based refrigerant piping and equipment will coexist with iron-based refrigerant piping and equipment such as stainless steel.

[0007] When refrigerant piping and equipment made of iron, such as stainless steel, coexist, it is necessary to properly join these dissimilar metals. However, joining copper to stainless steel is known to be difficult due to differences in physical properties and the presence of oxide films. It is desirable that these joining processes be carried out in a furnace with a controlled atmosphere, rather than in the open air. On the other hand, it is desirable that copper to copper be easily joined using conventional equipment and on-site methods.

[0008] To address these problems, a solution was devised to connect the components forming the refrigerant circuit of a refrigeration cycle system using refrigerant piping assemblies. A refrigerant piping assembly is a component in which copper pipes made of copper or copper alloy are joined to iron-based refrigerant pipes. A refrigerant piping assembly is obtained by joining the ends of the copper pipes to the ends of the iron-based refrigerant pipes by furnace brazing. By manufacturing the refrigerant piping assemblies in advance under appropriate conditions and then connecting them to the equipment using existing equipment, a low-cost refrigerant circuit with properly joined iron-based refrigerant pipes can be easily formed.

[0009] However, even with such measures in place, strength issues remain regarding the copper pipe portion of the refrigerant piping assembly. In refrigeration cycle systems, vibrations from the operation of the equipment affect the copper pipe portion near the compressor and valves that perform switching operations. If the strength of the copper pipe portion is low, fatigue failure may occur. Repeated stress due to vibration can cause the refrigerant piping assembly connected to the equipment to detach or the copper pipe portion to break.

[0010] In particular, refrigerant piping assemblies are formed by furnace brazing at high temperatures of around 800-1200°C for a long period of 20-30 minutes, so the copper pipe portion is subjected to significant thermal effects. The crystal grains tend to coarseen, leading to a decrease in tensile strength and fatigue strength. Near compressors that generate continuous vibrations, or valves that generate intermittent vibrations during switching, using conventional phosphorus-deoxidized copper subjected to furnace brazing increases the risk of fatigue failure.

[0011] Therefore, the present invention aims to provide a refrigeration cycle device that has high resistance to vibration of refrigerant piping and suppresses manufacturing costs. [Means for solving the problem]

[0012] To solve the aforementioned problems, the outdoor unit of a refrigeration cycle system according to the present invention is an outdoor unit of a refrigeration cycle system equipped with a compressor, a heat source side heat exchanger, a pressure reducer, a gas side shut-off valve and a liquid side shut-off valve, comprising: a first metal member arranged in a gas side refrigerant circuit connecting the gas side shut-off valve and the heat source side heat exchanger via at least the compressor; a second metal member arranged in a liquid side refrigerant circuit connecting the heat source side heat exchanger and the liquid side shut-off valve via at least the pressure reducer; a first copper pipe joined to the first metal member; and a second copper pipe joined to the second metal member, wherein the first metal member and the second metal member are made of iron, an iron alloy, or stainless steel; the first copper pipe is made of a copper alloy containing alloying elements; and the second copper pipe is made of copper that does not contain the alloying elements, or a copper alloy in which the content of the alloying elements is lower than that of the first copper pipe. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a refrigeration cycle device that has high resistance to vibration of the refrigerant piping and has reduced manufacturing costs. [Brief explanation of the drawing]

[0014] [Figure 1] A diagram showing a refrigerant circuit provided in a refrigeration cycle device according to the first embodiment. [Figure 2] A diagram showing a refrigerant circuit provided in a refrigeration cycle apparatus according to a second embodiment. [Figure 3] A diagram showing a refrigerant circuit provided in a refrigeration cycle apparatus according to a third embodiment. [Figure 4] A diagram showing a refrigerant circuit provided in a refrigeration cycle apparatus according to a fourth embodiment. [Figure 5] A diagram showing a refrigerant circuit provided in a refrigeration cycle apparatus according to a fifth embodiment. [Figure 6] A diagram showing a refrigerant circuit provided in a refrigeration cycle apparatus according to a sixth embodiment. [Figure 7] A diagram showing a refrigerant circuit provided in a refrigeration cycle apparatus according to a seventh embodiment. [Figure 8] A diagram showing a refrigerant circuit provided in a refrigeration cycle apparatus according to an eighth embodiment. [Figure 9] A diagram showing the results of measuring the fatigue characteristics of a copper-based refrigerant pipe. [Figure 10] A diagram showing an example of a joint portion between an iron-based refrigerant pipe and a copper pipe.

Mode for Carrying Out the Invention

[0015] Hereinafter, a refrigeration cycle apparatus according to an embodiment of the present invention will be described. In the following figures, the same reference numerals are assigned to common configurations, and redundant descriptions are omitted.

[0016] <First Embodiment> FIG. 1 is a diagram showing a refrigerant circuit provided in a refrigeration cycle apparatus according to a first embodiment of the present invention. FIG. 1 shows an example of a refrigerant circuit provided in an air conditioner, which is an example of a refrigeration cycle apparatus. As shown in FIG. 1, the air conditioner 1 includes an outdoor unit 100 installed outdoors and an indoor unit 200 installed on an indoor wall or the like.

[0017] The air conditioner 1 is a device that blows out heated air, cooled air, dehumidified air, etc. to adjust the temperature and humidity of a space. A refrigerant circulates between the outdoor unit 100 and the indoor unit 200 through a refrigerant pipe. In the outdoor unit 100, heat exchange between the refrigerant and the outside air takes place. In the indoor unit 200, heat exchange between the refrigerant and the indoor air takes place. The indoor unit 200 sucks in air from the room, exchanges heat with the refrigerant, and then blows it out into the room to adjust the temperature and humidity of the room.

[0018] As shown in FIG. 1, the air conditioner 1 includes a refrigerant circuit 10 that constitutes a heat pump. A refrigeration cycle for cooling operation, heating operation, dehumidifying operation, etc. is executed by the refrigerant circuit 10. The refrigerant circuit 10 is equipped with devices such as a compressor 2, a four-way valve 3, an outdoor heat exchanger 4, an outdoor expansion valve 5a, an indoor expansion valve 5b, an indoor heat exchanger 6, an accumulator 7, an oil separator 8, etc.

[0019] These devices are connected to each other via refrigerant pipes through which the refrigerant flows. To the outdoor unit 100, a gas pipe, which is a refrigerant pipe, is connected between it and the indoor unit 200 via a gas-side stop valve 18, and a liquid pipe, which is a refrigerant pipe, is connected via a liquid-side stop valve 19. These devices and refrigerant pipes form a refrigerant circuit 10, which is a closed circuit through which the refrigerant circulates between the outdoor unit 100 and the indoor unit 200.

[0020] The refrigerant circuit 10 is filled with a refrigerant. The refrigerant circulates through the refrigerant circuit 10 and exchanges heat with the indoor air and the outside air for cooling operation, heating operation, dehumidifying operation, etc. The outdoor unit 100 houses a compressor 2, a four-way valve 3, an outdoor heat exchanger 4, an outdoor expansion valve 5a, an accumulator 7, an oil separator 8, an outdoor blower fan 16, etc. The indoor unit 200 houses an indoor expansion valve 5b, an indoor heat exchanger 6, an indoor blower fan 17, etc.

[0021] The compressor 2 is a device that compresses the refrigerant. It draws in low-pressure gaseous refrigerant, compresses it adiabatically, and discharges high-pressure gaseous refrigerant. The compressor 2 may be configured to variably control the amount of refrigerant circulated by inverter control. The compressor 2 can be a sealed electric compressor of an appropriate type, such as a scroll type, single rotary type, twin rotary type, swing type, piston type, screw type, or centrifugal type. However, the scroll type or twin rotary type is preferred because it produces less vibration during operation.

[0022] The four-way valve 3 has four ports and a valve body that switches the connection of the flow paths between the ports, and the connection of the flow paths between the ports is changed according to the operating mode, such as cooling operation or heating operation. The four-way valve 3 switches the circulation direction of the refrigerant discharged from the compressor 2 in the refrigerant circuit 10. In Figure 2, the solid arrows indicate the circulation direction of the refrigerant during cooling operation. The dashed arrows indicate the circulation direction of the refrigerant during heating operation.

[0023] The outdoor heat exchanger 4 is a heat exchanger that exchanges heat between the refrigerant and the outside air. It functions as a condenser during cooling operation and as an evaporator during heating operation. The outdoor blower fan 16 blows outside air to the outdoor heat exchanger 4 to promote heat exchange. The outdoor blower fan 16 is, for example, a propeller fan. The outdoor expansion valve 5a is an electronically controlled valve with an adjustable opening degree. It functions as a pressure reducer that expands the refrigerant during heating operation. Also, if the indoor expansion valve 5b is not provided, the outdoor expansion valve 5a functions as a pressure reducer that expands the refrigerant even during cooling operation.

[0024] In Figure 1, the outdoor heat exchanger 4 comprises a main body 4a and a header pipe 4b. A distributor 4c is connected to the outdoor expansion valve 5a side of the main body 4a via refrigerant piping. The main body 4a is a cross-fin tube type heat exchanger that exchanges heat in parallel flow and comprises multiple heat transfer tubes through which the refrigerant flows, and multiple fins joined to the heat transfer tubes. The heat transfer tubes and fins are made of, for example, copper, copper alloy, aluminum alloy, etc.

[0025] The header pipe 4b is a device that divides one flow path into multiple flow paths or merges multiple flow paths into one flow path, depending on the direction of refrigerant flow. The header pipe 4b has an opening on the four-way valve 3 side that forms a single flow path, and the refrigerant piping is connected between it and the four-way valve 3. The header pipe 4b has an opening on the main body 4a side that forms multiple flow paths, and the heat transfer tubes of the main body 4a are connected to it.

[0026] The distributor 4c is a device that merges multiple flow paths into one flow path or divides one flow path into multiple flow paths, depending on the direction of refrigerant flow. The main body 4a side of the distributor 4c has openings that form multiple flow paths, and refrigerant piping is connected between it and the heat transfer tubes of the main body 4a. The outdoor expansion valve 5a side of the distributor 4c also has openings that form multiple flow paths, and refrigerant piping is connected between it and the outdoor expansion valve 5a.

[0027] The indoor expansion valve 5b acts as a pressure reducer that expands the refrigerant during cooling operation. The indoor heat exchanger 6 is a heat exchanger that exchanges heat between the refrigerant and the indoor air, acting as an evaporator during cooling operation and as a condenser during heating operation. The indoor blower fan 17 blows air into the indoor heat exchanger 6 to promote heat exchange and blows the air that has exchanged heat with the refrigerant into the room. The indoor blower fan 17 is, for example, made up of a cylindrical through-fan.

[0028] The accumulator 7 is a tank-shaped device that performs gas-liquid separation of gaseous refrigerant and liquid refrigerant, separating and storing the liquid refrigerant contained in the gaseous refrigerant. The accumulator 7 removes any liquid refrigerant that has not completely evaporated from the gaseous refrigerant on the suction side of the compressor 2. By removing the liquid refrigerant, liquid compression in the compressor 2, which can cause abnormal noise and malfunctions, is prevented.

[0029] The oil separator 8 is a device that separates the refrigerant from the refrigerant oil. The oil separator 8 separates the refrigerant oil discharged from the compressor 2 together with the refrigerant. The refrigerant oil separated by the oil separator 8 is returned to the compressor 2 without circulating through the refrigerant circuit 10. By separating and returning the refrigerant oil, oil shortage in the compressor 2 and performance degradation due to contamination of the refrigerant circulating in the refrigerant circuit 10 are prevented.

[0030] The cooling operation of air conditioner 1 is carried out as follows: The high-temperature, high-pressure gaseous refrigerant adiabatically compressed by compressor 2 is sent to outdoor heat exchanger 4 through four-way valve 3. The high-temperature, high-pressure gaseous refrigerant condenses into liquid refrigerant through heat exchange with the outside air in outdoor heat exchanger 4, which acts as a condenser. The liquid refrigerant is depressurized and expanded in indoor expansion valve 5b to become a low-temperature, low-pressure gas-liquid two-phase refrigerant containing a small amount of gaseous refrigerant.

[0031] The low-temperature, low-pressure gaseous two-phase refrigerant is sent to the indoor heat exchanger 6. The gaseous two-phase refrigerant evaporates in the indoor heat exchanger 6, which acts as an evaporator, through heat exchange with the indoor air, becoming a low-temperature, low-pressure gaseous refrigerant. The low-temperature, low-pressure gaseous refrigerant passes through the four-way valve 3, and after the liquid refrigerant is separated in the accumulator 7, it returns to the compressor 2. The indoor air loses heat through heat exchange with the refrigerant in the indoor heat exchanger 6, which acts as an evaporator. This cycle is repeated, and the room is cooled.

[0032] The heating operation of the air conditioner 1 is performed in the reverse cycle of the cooling operation. The high-temperature, high-pressure gaseous refrigerant discharged by adiabatically compressed compressor 2 is sent to the indoor heat exchanger 6 by switching the four-way valve 3. The high-temperature, high-pressure gaseous refrigerant is cooled by heat exchange with the indoor air in the indoor heat exchanger 6, which acts as a condenser, and becomes liquid refrigerant. The liquid refrigerant is then depressurized by the outdoor expansion valve 5a to become low-temperature, low-pressure liquid refrigerant.

[0033] Low-temperature, low-pressure liquid refrigerant is sent to the outdoor heat exchanger 4. The low-temperature, low-pressure liquid refrigerant evaporates in the outdoor heat exchanger 4, which acts as an evaporator, through heat exchange with the outside air, becoming low-temperature, low-pressure gaseous refrigerant. The low-temperature, low-pressure gaseous refrigerant passes through the four-way valve 3, and after the liquid refrigerant is separated in the accumulator 7, it returns to the compressor 2. The indoor air is heated in the indoor heat exchanger 6, which acts as a condenser, through heat exchange with the refrigerant. This cycle is repeated, heating the room.

[0034] In the air conditioner 1 according to this embodiment, the refrigerant circuit 10 may be filled with a single refrigerant consisting of a single refrigerant component, or with a mixed refrigerant consisting of multiple refrigerant components. As the mixed refrigerant, an azeotropic mixed refrigerant or a non-azeotropic mixed refrigerant may be used. As the refrigerant, one or more of the following can be used: hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), CO2, hydrocarbons, ethers, fluoroethers, fluoroalkenes, etc. Additives such as stabilizers that suppress the decomposition of refrigerant components and polymerization inhibitors that suppress the polymerization of refrigerant components may be added to the refrigerant.

[0035] In the air conditioner 1 according to this embodiment, a predetermined refrigerant oil is injected into the compressor 2. The refrigerant oil is drawn from an oil reservoir during the operation of the compressor 2 and supplied to sliding parts such as the compression mechanism and bearings. The refrigerant oil lubricates, cools, and seals the sliding parts. Polyol ester oil, polyvinyl ether oil, polyalkylene glycol oil, etc. can be used as the refrigerant oil. Additives such as acid scavengers, antioxidants, extreme pressure agents, stabilizers, defoamers, and metal deactivators may be added to the refrigerant oil.

[0036] As shown in Figure 1, in the air conditioner 1 according to this embodiment, at least a portion of the refrigerant circuit 10 is formed by an assembly. The assembly is a component in which copper pipes are joined to an iron-based metal member. The metal member is a metal component that forms part of the refrigerant circuit 10 and consists of refrigerant piping that forms the refrigerant circuit 10, and parts of the equipment that executes the refrigeration cycle, such as the main body of the equipment and piping joined to the connection parts of the equipment.

[0037] The assembly can be connected to one or more of the metal members that form the refrigerant circuit 10. In Figure 1, the connection parts of the equipment forming the refrigerant circuit 10, such as the compressor 2 and accumulator 7, are made of copper members 20. The copper members 20 are members joined to the main body of the equipment or to the connection parts of the equipment and are provided integrally with the equipment. The copper members 20 are made of copper or a copper alloy, such as phosphorus-deoxidized copper. The assembly is joined to such metal members using the same type of metal.

[0038] In Figure 1, the assembly includes refrigerant piping assemblies 10a and 10b. The refrigerant piping assemblies 10a and 10b are refrigerant piping in which copper pipes 13 and 14 are joined to iron-based refrigerant pipes 11 and 12 that constitute iron-based metal members. The refrigerant piping assemblies 10a and 10b function as refrigerant piping and can be connected to refrigerant piping that forms a refrigerant circuit 10 or to equipment that forms a refrigerant circuit 10.

[0039] The refrigerant piping assemblies 10a and 10b are pre-assembled, component-like refrigerant piping, formed from iron-based refrigerant pipes 11 and 12 and copper pipes 13 and 14. The iron-based refrigerant pipes 11 and 12 and the copper pipes 13 and 14 are joined to each other by furnace brazing. Furnace brazing can be performed in an atmosphere where, for example, the oxygen concentration, moisture content, hydrogen concentration, etc., are controlled.

[0040] For the iron-based refrigerant piping 11 and 12, iron pipes, iron alloy pipes, or stainless steel pipes can be used. Examples of iron and iron alloys include iron steel, carbon steel, and alloy steel. Examples of stainless steel include austenitic stainless steel such as SUS304. Using iron-based refrigerant piping 11 and 12 may reduce raw material costs compared to using copper-based piping.

[0041] Copper pipes 13 and 14 can be made of copper or a copper alloy. Examples of copper include phosphorus-deoxidized copper, oxygen-free copper, and tough pitch copper. Examples of copper alloys include alloys in which copper is the main component and one or more of the following alloying elements are present: phosphorus (P), cobalt (Co), tin (Sn), zinc (Zn), nickel (Ni), zirconium (Zr), and iron (Fe). Using copper pipes 13 and 14 facilitates connection to existing copper-based refrigerant piping and equipment that form the refrigerant circuit 10. In addition, galvanic corrosion caused by joining dissimilar metals is suppressed.

[0042] Examples of copper alloys include copper-based alloys containing Co, Sn, Zn, Ni, Zr, and Fe in a content of 0.01% by mass or more. Alternatively, copper-based alloys containing phosphorus (P) in a content exceeding 0.040% by mass may be used. As copper alloys, solid-solution strengthened copper alloys, where alloying elements are solid-solved, or precipitation-strengthened copper alloys, where alloying elements exceeding the solid-solution limit are precipitated, can be used. Using such copper alloys improves mechanical properties such as tensile strength and fatigue strength, thereby reducing fatigue failure of copper pipes even when vibrations occur during equipment operation.

[0043] The refrigerant piping assemblies 10a and 10b can be joined to other refrigerant piping and equipment forming the refrigerant circuit 10 by methods such as atmospheric brazing, flare connections, and welding. When assembling the refrigerant circuit 10, the copper pipes 13 and 14 at the ends of the refrigerant piping assemblies 10a and 10b, formed by furnace brazing, can be easily joined to existing copper-based refrigerant piping and equipment using conventional equipment. Furthermore, since heating of the copper pipes 13 and 14 in the furnace can be avoided, a decrease in strength due to grain coarsening can be suppressed.

[0044] The refrigerant piping assemblies 10a and 10b may be formed by joining copper pipes 13 and 14 to one end of iron-based refrigerant piping 11 and 12, or by joining them to both ends of iron-based refrigerant piping 11 and 12. However, when connecting the refrigerant piping assemblies 10a and 10b to copper-based refrigerant piping or equipment, it is preferable that the copper pipes 13 and 14 are pre-joined to the corresponding ends of the refrigerant piping assemblies 10a and 10b.

[0045] In Figure 1, the refrigerant piping assemblies 10a and 10b consist of a first refrigerant piping assembly 10a and a second refrigerant piping assembly 10b, which are connected between devices on the refrigerant circuit 10.

[0046] The first refrigerant piping assembly 10a is formed by joining a first copper pipe 13, which is made of a copper alloy, to an iron-based first refrigerant pipe 11, which is made of iron, an iron alloy, or stainless steel. The first copper pipe 13 is made of a copper alloy containing one or more alloying elements from Co, Sn, Zn, Ni, Zr, and Fe, and more than 0.040 mass% of P. The first copper pipe 13 is a refrigerant pipe made of a copper alloy in which mechanical properties such as tensile strength and fatigue strength are enhanced by solid solution strengthening or precipitation strengthening through the addition of alloying elements.

[0047] The first copper tube 13 may contain, for example, Co in a content of more than 0.01 mass% and 0.5 mass% or less, preferably 0.04 mass% to 0.2 mass%. It may contain Sn in a content of more than 0.01 mass% and 1.0 mass% or less, preferably 0.05 mass% to 0.8 mass%. It may contain Zn in a content of more than 0.01 mass% and 0.5 mass% or less, preferably 0.02 mass% to 0.2 mass%. It may contain Ni in a content of more than 0.01 mass% and 1.0 mass% or less, preferably 0.02 mass% to 0.5 mass%. It may contain Zr in a content of more than 0.01 mass% and 0.5 mass% or less, preferably 0.04 mass% to 0.1 mass%. It may contain Fe in a content of more than 0.01 mass% and 5.0 mass% or less, preferably 1 mass% to 3.0 mass%.

[0048] The Cu content of the first copper pipe 13 is preferably 95% by mass or more, more preferably 97% by mass or more, and even more preferably 99% by mass or more. The P content may be 0.015% by mass or more and 0.040% by mass or less, or more than 0.040% by mass. The content of the alloying elements in the first copper pipe 13 relative to the base metal, which is the main component, is preferably lower than the content of the alloying elements in the iron-based first refrigerant piping 11 relative to the base metal, which is the main component.

[0049] The second refrigerant piping assembly 10b is formed by joining a second copper pipe 14, made of copper or a copper alloy, to an iron-based second refrigerant pipe 12, which is made of iron, an iron alloy, or stainless steel. The second copper pipe 14 is made of copper that is substantially free of one or more alloying elements from Co, Sn, Zn, Ni, Zr, and Fe through active addition, or of a copper alloy in which the content of these alloying elements relative to the base metal, which is the main component, is lower than the content in the first copper pipe 13. The second copper pipe 14 can be made of phosphorus-deoxidized copper or low-cost low-alloy copper with few alloying elements.

[0050] In Figure 1, the refrigerant circuit 10 is formed by connecting a compressor 2, a four-way valve 3, an outdoor heat exchanger 4 which is a heat source side heat exchanger, an outdoor expansion valve 5a and an indoor expansion valve 5b which are pressure reducers, an indoor heat exchanger 6 which is a utilization side heat exchanger, an accumulator 7, an oil separator 8, a gas side shutoff valve 18, and a liquid side shutoff valve 19 via refrigerant piping. The refrigerant circuit 10 is composed of at least a gas side refrigerant circuit 10A, a liquid side refrigerant circuit 10B, and a utilization side refrigerant circuit 10C.

[0051] The gas-side refrigerant circuit 10A connects the compressor 2 and the outdoor heat exchanger 4, which is the heat source side heat exchanger, within the refrigerant circuit 10, without passing through the outdoor expansion valve 5a, which is the pressure reducer. The gas-side refrigerant circuit 10A connects the gas-side shutoff valve 18 and the outdoor heat exchanger 4 via the compressor 2, etc. A first metal member to which the first copper pipe 13 is joined is arranged in at least a portion of the gas-side refrigerant circuit 10A.

[0052] The liquid-side refrigerant circuit 10B connects the outdoor heat exchanger 4 and the liquid-side blocking valve 19 via an outdoor expansion valve 5a, etc. A second metal member to which the second copper pipe 14 is joined is arranged in at least a portion of the liquid-side refrigerant circuit 10B.

[0053] The user-side refrigerant circuit 10C connects the indoor end of the gas-side refrigerant circuit 10A and the indoor end of the liquid-side refrigerant circuit 10B via the indoor heat exchanger 6, which is the user-side heat exchanger. The user-side refrigerant circuit 10C is a refrigerant circuit built into the indoor unit 200. In at least a portion of the user-side refrigerant circuit 10C, a first metal member to which the first copper pipe 13 is joined and a second metal member to which the second copper pipe 14 is joined can be arranged as required.

[0054] As shown in Figure 1, the first refrigerant piping assembly 10a is a gas-side refrigerant circuit 10A and can be connected to one or more of the following sections: between the accumulator 7 and the compressor 2, between the compressor 2 and the oil separator 8, between the oil separator 8 and the four-way valve 3, between the four-way valve 3 and the gas-side shutoff valve 18, between the four-way valve 3 and the accumulator 7, and between the four-way valve 3 and the outdoor heat exchanger 4.

[0055] In other words, the first iron-based metal component, the first iron-based refrigerant piping 11, can be positioned between the accumulator 7 and the compressor 2, between the compressor 2 and the oil separator 8, between the oil separator 8 and the four-way valve 3, between the four-way valve 3 and the gas-side shutoff valve 18, between the four-way valve 3 and the accumulator 7, or between the four-way valve 3 and the outdoor heat exchanger 4, by incorporating the first refrigerant piping assembly 10a. The first copper pipe 13 is pre-joined to the end of such an iron-based first refrigerant piping 11. The first copper pipe 13 can be connected to the four-way valve 3 side of the header pipe 4b, etc., with respect to the outdoor heat exchanger 4.

[0056] These sections are close to the compressor 2, which generates continuous vibrations during operation, and the four-way valve 3, which generates intermittent vibrations during switching. Connecting unreinforced refrigerant piping made of phosphorus-deoxidized copper or the like to such sections may cause fatigue failure due to repeated stress from vibrations during equipment operation. In contrast, the first refrigerant piping assembly 10a is reinforced by alloying elements in the first copper pipe 13 that constitutes its end, thus suppressing fatigue failure due to vibration. Therefore, the risk of the first refrigerant piping assembly 10a falling off or the fracture of the parts made of copper-based metals can be reduced.

[0057] On the other hand, the second refrigerant piping assembly 10b is a liquid-side refrigerant circuit 10B that can be connected to one or more sections between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, and between the outdoor expansion valve 5a and the liquid-side blocking valve 19.

[0058] In other words, the iron-based second refrigerant piping 12, which is an iron-based second metal component, can be positioned between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, or between the outdoor expansion valve 5a and the liquid side shutoff valve 19, by incorporating the second refrigerant piping assembly 10b. The second copper pipe 14 is pre-joined to the end of such iron-based second refrigerant piping 12. The second copper pipe 14 can be connected to the distributor 4c side of the main body 4a of the outdoor heat exchanger 4, or to the main body 4a side or the outdoor expansion valve 5a side of the distributor 4c, etc.

[0059] These sections are not close to the compressor 2, which generates continuous vibrations during operation, or the four-way valve 3, which generates intermittent vibrations during switching. Since the outdoor heat exchanger 4 is interposed between these sections and the compressor 2 and the four-way valve 3, vibrations from the operation of the equipment are less likely to reach them. For these sections, conventional phosphorus-deoxidized copper pipes or low-alloy copper pipes, which have fewer alloying elements and thus lower raw material costs, can be used as the ends of the refrigerant piping assembly 10b. By using such refrigerant piping, the refrigerant circuit 10 can be formed at low cost without causing fatigue failure due to vibration.

[0060] Furthermore, the first refrigerant piping assembly 10a and the second refrigerant piping assembly 10b can also be connected to one or more sections of the user-side refrigerant circuit 10C, specifically between the indoor heat exchanger 6 and the indoor expansion valve 5b, between the indoor expansion valve 5b and the liquid-side shutoff valve 19, and between the indoor heat exchanger 6 and the gas-side shutoff valve 18. In Figure 1, the second refrigerant piping assembly 10b is connected to these sections, but if vibration or strength is a problem in the indoor unit 200, the first refrigerant piping assembly 10a may be connected to these sections.

[0061] Furthermore, it is preferable that the length of the first copper pipe 13 along its centerline on the refrigerant circuit 10 be shorter than the length of the first iron-based refrigerant pipe 11 along its centerline. Also, it is preferable that the length of the second copper pipe along its centerline be shorter than the length of the second iron-based refrigerant pipe 12 along its centerline.

[0062] With this length relationship, the length ratio of iron-based refrigerant piping becomes larger in the first refrigerant piping assembly 10a and the second refrigerant piping assembly 10b compared to copper piping, thus enabling lower costs for the first refrigerant piping assembly 10a and the second refrigerant piping assembly 10b.

[0063] However, in the section connecting the oil outlet of the oil separator 8 and the compressor 2, it is preferable that the length along the centerline of the iron-based first refrigerant piping 11 is shorter than the length along the centerline of the first copper pipe 13 joined to the iron-based first refrigerant piping 11. In the section connecting the oil outlet of the oil separator 8 and the compressor 2, the first refrigerant piping assembly 10a may not be provided, and copper-based refrigerant piping made of copper or a copper alloy may be connected.

[0064] The section connecting the oil outlet of the oil separator 8 to the compressor 2 is where the refrigerant oil is returned to the compressor 2, and is generally made short. Therefore, this section is one in which there is little need to convert copper-based refrigerant piping to iron-based refrigerant piping. This length relationship allows for greater design flexibility in the refrigerant circuit 10 and helps to reduce overall costs.

[0065] In the refrigerant circuit 10, it is preferable that the thickness of the wall of the iron-based first refrigerant pipe 11 is greater than the thickness of the wall of the iron-based second refrigerant pipe 12. Furthermore, it is preferable that the thickness of the wall of the first copper pipe 13 is greater than the thickness of the wall of the iron-based first refrigerant pipe 11 and the thickness of the wall of the iron-based second refrigerant pipe 12. Furthermore, it is preferable that the thickness of the wall of the second copper pipe 14 is greater than the thickness of the wall of the iron-based first refrigerant pipe 11 and the thickness of the wall of the iron-based second refrigerant pipe 12.

[0066] With this wall thickness relationship, the refrigerant piping is made relatively thicker in the sections through which gaseous refrigerant flows, thus ensuring adequate pressure resistance for the refrigerant piping. Furthermore, in the first refrigerant piping assembly 10a and the second refrigerant piping assembly 10b, the ratio of iron-based refrigerant piping thickness to copper piping is larger, allowing for lower costs for the first refrigerant piping assembly 10a and the second refrigerant piping assembly 10b.

[0067] When the first refrigerant piping assembly 10a is connected to the compressor 2, that is, when the iron-based first refrigerant piping 11 constitutes piping connected between the compressor 2 and the accumulator 7, between the compressor 2 and the oil separator 8, or between the compressor 2 and the four-way valve 3, and the first copper pipe 13 is joined to the discharge side or suction side of the compressor 2, the compressor 2 is preferably a scroll compressor or a twin rotary compressor.

[0068] With this type of compressor 2, vibrations generated during the operation of the compressor 2 are reduced compared to single rotary type, swing type, etc. Therefore, even when the first copper pipe 13 constituting the first refrigerant piping assembly 10a is strengthened by the addition of alloying elements, fatigue failure of the first refrigerant piping assembly 10a and the first copper pipe 13 constituting the first refrigerant piping assembly 10a can be further reduced.

[0069] In this type of air conditioner 1, the refrigerant circuit 10 is formed using refrigerant piping assemblies 10a and 10b. After joining the copper pipe and the iron-based refrigerant piping in advance by furnace brazing under controlled atmosphere, the ends of the copper pipes joined to the iron-based refrigerant piping can be connected to existing copper-based refrigerant piping and equipment in any atmosphere, such as air. Since a portion of the refrigerant circuit 10 is replaced with iron-based refrigerant piping, it is possible to connect to existing copper-based refrigerant piping and equipment using conventional equipment and methods while reducing material costs. Therefore, even though there are joints between dissimilar metals, the iron-based refrigerant piping is properly joined to the copper-based refrigerant piping and equipment, and a refrigeration cycle device with reduced manufacturing costs can be provided.

[0070] Furthermore, the refrigerant piping assemblies 10a and 10b have different chemical compositions for the copper pipes that make up their ends, depending on their position relative to the equipment that generates vibration, thereby increasing the vibration resistance of the refrigerant piping. For copper pipes connected to the compressor 2 and four-way valve 3, which generate vibration during operation, the tensile strength and fatigue strength are enhanced by solid solution strengthening or precipitation strengthening through the addition of alloying elements. On the other hand, for copper pipes not connected to these, costs are suppressed by omitting or reducing the addition of alloying elements. Therefore, it is possible to provide a refrigeration cycle system that has high vibration resistance to the refrigerant piping, suppresses detachment and breakage of the refrigerant piping, and has reduced manufacturing costs.

[0071] <Second Embodiment> Figure 2 is a diagram showing a refrigerant circuit provided in a refrigeration cycle device according to a second embodiment of the present invention. Figure 2 shows an example of a refrigerant circuit provided in an air conditioner, which is an example of a refrigeration cycle device. As shown in Figure 2, the air conditioner 2 may also be equipped with an iron-based oil separator 8a made of iron, an iron alloy, or stainless steel. The iron-based oil separator 8a can be incorporated as an assembly with respect to the refrigerant circuit 10. Other main components of the air conditioner 2 are the same as those of the air conditioner 1 described above.

[0072] The iron-based oil separator 8a can be provided as an oil separator assembly 10c. The oil separator assembly 10c is an assembly in which a first copper pipe 13 is joined to the connection portion of the iron-based oil separator 8a, which constitutes an iron-based metal component. The oil separator assembly 10c can be connected to refrigerant piping that forms the refrigerant circuit 10, or to equipment that forms the refrigerant circuit 10.

[0073] The oil separator assembly 10c is a pre-assembled component formed from an iron-based oil separator 8a and a first copper tube 13. The first copper tube 13 is made of a copper alloy containing one or more alloying elements from Co, Sn, Zn, Ni, Zr, and Fe, and more than 0.040 mass% of P. The first copper tube 13 is made of a copper alloy whose mechanical properties, such as tensile strength and fatigue strength, are enhanced by solid solution strengthening or precipitation strengthening through the addition of alloying elements. The iron-based oil separator 8a and the first copper tube 13 are joined to each other by furnace brazing.

[0074] As the iron-based oil separator 8a, an oil separator with a body and connection parts made of iron, an oil separator with a body and connection parts made of iron alloy, or an oil separator with a body and connection parts made of stainless steel can be used. The first copper pipe 13 may be connected to each port of the iron-based oil separator 8a, or it may be connected to the end of an iron-based refrigerant pipe that is pre-connected to each port of the iron-based oil separator 8a.

[0075] Examples of iron and iron alloys include steel, carbon steel, and alloy steel. Examples of stainless steel include austenitic stainless steel such as SUS304. Using an iron-based oil separator 8a may reduce raw material costs compared to using a copper-based one.

[0076] The oil separator assembly 10c can be joined to other refrigerant piping and equipment forming the refrigerant circuit 10 by, for example, brazing in air, flare connection, welding, etc. When assembling the refrigerant circuit 10, the oil separator assembly 10c formed by furnace brazing can be easily joined to existing copper-based refrigerant piping and equipment using conventional equipment. In addition, since the first copper tube 13 is not heated in the furnace, a decrease in strength due to grain coarsening can be prevented.

[0077] The oil separator assembly 10c may be formed by joining the first copper pipe 13 to some of the connection parts of the iron-based oil separator 8a, or by joining it to all of the connection parts of the iron-based oil separator 8a. However, when connecting the oil separator assembly 10c to copper-based refrigerant piping or equipment, it is preferable that the first copper pipe 13 is joined to the corresponding connection part of the oil separator assembly 10c.

[0078] In Figure 2, the refrigerant circuit 10 is formed by connecting a compressor 2, a four-way valve 3, an outdoor heat exchanger 4 which is a heat source side heat exchanger, an outdoor expansion valve 5a and an indoor expansion valve 5b which are pressure reducers, an indoor heat exchanger 6 which is a utilization side heat exchanger, an accumulator 7, an iron-based oil separator 8a, a gas side shutoff valve 18, and a liquid side shutoff valve 19 via refrigerant piping. The refrigerant circuit 10 is composed of at least a gas side refrigerant circuit 10A, a liquid side refrigerant circuit 10B, and a utilization side refrigerant circuit 10C.

[0079] As shown in Figure 2, the oil separator assembly 10c is part of the gas-side refrigerant circuit 10A and can be connected between the compressor 2 and the four-way valve 3. That is, the iron-based oil separator 8a, which constitutes the first iron-based metal component, can be positioned between the compressor 2 and the four-way valve 3 by incorporating the oil separator assembly 10c. The first copper pipe 13 is pre-joined to the connection portion of the iron-based oil separator 8a.

[0080] Furthermore, the first refrigerant piping assembly 10a is a gas-side refrigerant circuit 10A and can be connected to one or more of the following sections: between the accumulator 7 and the compressor 2, between the four-way valve 3 and the gas-side shutoff valve 18, between the four-way valve 3 and the accumulator 7, and between the four-way valve 3 and the outdoor heat exchanger 4.

[0081] In other words, the first iron-based metal component, the first iron-based refrigerant piping 11, can be positioned between the accumulator 7 and the compressor 2, between the four-way valve 3 and the gas-side shutoff valve 18, between the four-way valve 3 and the accumulator 7, or between the four-way valve 3 and the outdoor heat exchanger 4 by incorporating the first refrigerant piping assembly 10a. The first copper pipe 13 is pre-joined to the end of such an iron-based first refrigerant piping 11. The first copper pipe 13 can be connected to the four-way valve 3 side of the header pipe 4b, etc., with respect to the outdoor heat exchanger 4.

[0082] On the other hand, the second refrigerant piping assembly 10b is a liquid-side refrigerant circuit 10B that can be connected to one or more sections between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, and between the outdoor expansion valve 5a and the liquid-side blocking valve 19.

[0083] In other words, the iron-based second refrigerant piping 12, which is an iron-based second metal component, can be positioned between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, or between the outdoor expansion valve 5a and the liquid side shutoff valve 19, by incorporating the second refrigerant piping assembly 10b. The second copper pipe 14 is pre-joined to the end of such iron-based second refrigerant piping 12. The second copper pipe 14 can be connected to the distributor 4c side of the main body 4a of the outdoor heat exchanger 4, or to the main body 4a side or the outdoor expansion valve 5a side of the distributor 4c, etc.

[0084] Furthermore, the first refrigerant piping assembly 10a and the second refrigerant piping assembly 10b can also be connected to one or more sections of the user-side refrigerant circuit 10C, specifically between the indoor heat exchanger 6 and the indoor expansion valve 5b, between the indoor expansion valve 5b and the liquid-side shutoff valve 19, and between the indoor heat exchanger 6 and the gas-side shutoff valve 18. In Figure 2, the second refrigerant piping assembly 10b is connected to these sections, but if vibration or strength is a problem in the indoor unit 200, the first refrigerant piping assembly 10a may be connected to these sections.

[0085] Furthermore, it is preferable that the length of the first copper pipe 13 along its centerline, the length of the second copper pipe 14 along its centerline, the thickness of the pipe wall of the iron-based first refrigerant pipe 11, the thickness of the pipe wall of the iron-based second refrigerant pipe 12, the thickness of the pipe wall of the first copper pipe 13, the thickness of the pipe wall of the second copper pipe 14, and the type of compressor 2 are provided in the same manner as in the air conditioner 1 described above.

[0086] In this type of air conditioner 2, the refrigerant circuit 10 is formed using refrigerant piping assemblies 10a, 10b and an oil separator assembly 10c. After pre-joining copper pipes with iron-based refrigerant piping and iron-based oil separators by furnace brazing under controlled atmosphere, the ends of the copper pipes joined to the iron-based refrigerant piping and iron-based oil separators can be connected to existing copper-based refrigerant piping and equipment in any atmosphere, such as air. Since a portion of the refrigerant circuit 10 is replaced with iron-based refrigerant piping and equipment, it is possible to reduce material costs while enabling connections to existing copper-based refrigerant piping and equipment using conventional equipment and methods. Therefore, even though there are joints between dissimilar metals, iron-based refrigerant piping and equipment are properly joined to copper-based refrigerant piping and equipment, providing a refrigeration cycle device with reduced manufacturing costs.

[0087] Furthermore, the refrigerant piping assemblies 10a and 10b and the oil separator assembly 10c have different chemical compositions for the copper pipes that make up their ends, depending on their position relative to the equipment that generates vibration, thereby increasing the vibration resistance of the refrigerant piping. For copper pipes connected to the compressor 2 and the four-way valve 3, which generate vibration during operation, the tensile strength and fatigue strength are enhanced by solid solution strengthening or precipitation strengthening through the addition of alloying elements. On the other hand, for copper pipes not connected to these, costs are suppressed by omitting or reducing the addition of alloying elements. Therefore, it is possible to provide a refrigeration cycle system that has high vibration resistance to the refrigerant piping, suppresses detachment and breakage of the refrigerant piping, and has reduced manufacturing costs.

[0088] <Third Embodiment> Figure 3 is a diagram showing a refrigerant circuit provided in a refrigeration cycle device according to a third embodiment of the present invention. Figure 3 shows an example of a refrigerant circuit provided in an air conditioner, which is an example of a refrigeration cycle device. As shown in Figure 3, the air conditioner 3 may also be equipped with an iron-based four-way valve 3a made of iron, an iron alloy, or stainless steel. The iron-based four-way valve 3a can be incorporated as an assembly with respect to the refrigerant circuit 10. Other main components of the air conditioner 3 are the same as those of the air conditioner 1 described above.

[0089] The iron-based four-way valve 3a can be provided as a four-way valve assembly 10d. The four-way valve assembly 3d is an assembly in which the first copper pipe 13 is joined to the connection part of the iron-based four-way valve 3a, which constitutes an iron-based metal component. The four-way valve assembly 3d can be connected to refrigerant piping that forms the refrigerant circuit 10, or to equipment that forms the refrigerant circuit 10.

[0090] The four-way valve assembly 10d is a pre-assembled component, formed from an iron-based four-way valve 3a and a first copper tube 13. The first copper tube 13 is made of a copper alloy containing one or more alloying elements from Co, Sn, Zn, Ni, Zr, and Fe, and more than 0.040 mass% of P. The first copper tube 13 is made of a copper alloy whose mechanical properties, such as tensile strength and fatigue strength, are enhanced by solid solution strengthening or precipitation strengthening through the addition of alloying elements. The iron-based four-way valve 3a and the first copper tube 13 are joined to each other by furnace brazing.

[0091] As the iron-based four-way valve 3a, a four-way valve whose body and connecting parts are made of iron, a four-way valve whose body and connecting parts are made of an iron alloy, or a four-way valve whose body and connecting parts are made of stainless steel can be used. The first copper pipe 13 may be connected to each port of the iron-based four-way valve 3a, or it may be connected to the end of an iron-based refrigerant pipe that is pre-connected to each port of the iron-based four-way valve 3a.

[0092] Examples of iron and iron alloys include steel, carbon steel, and alloy steel. Examples of stainless steel include austenitic stainless steel such as SUS304. Using an iron-based four-way valve 3a may reduce raw material costs compared to using a copper-based valve.

[0093] The four-way valve assembly 10d can be joined to other refrigerant piping and equipment forming the refrigerant circuit 10 by, for example, brazing in air, flare connection, welding, etc. When assembling the refrigerant circuit 10, the four-way valve assembly 10d formed by furnace brazing can be easily joined to existing copper-based refrigerant piping and equipment using conventionally used equipment. In addition, since the first copper pipe 13 is not heated in the furnace, a decrease in strength due to grain coarsening can be prevented.

[0094] The four-way valve assembly 10d may be formed by joining the first copper pipe 13 to some of the connection parts of the iron-based four-way valve 3a, or by joining it to all of the connection parts of the iron-based four-way valve 3a. However, when connecting the four-way valve assembly 10d to copper-based refrigerant piping or equipment, it is preferable that the first copper pipe 13 is joined to the corresponding connection part of the four-way valve assembly 10d.

[0095] In Figure 3, the refrigerant circuit 10 is formed by connecting a compressor 2, an iron-based four-way valve 3a, an outdoor heat exchanger 4 which is a heat source side heat exchanger, an outdoor expansion valve 5a which is a pressure reducer, an indoor expansion valve 5b which is a pressure reducer, an indoor heat exchanger 6 which is a heat utilization side heat exchanger, an accumulator 7, an oil separator 8, a gas side shutoff valve 18, and a liquid side shutoff valve 19 via refrigerant piping. The refrigerant circuit 10 is composed of at least a gas side refrigerant circuit 10A, a liquid side refrigerant circuit 10B, and a utilization side refrigerant circuit 10C.

[0096] As shown in Figure 3, the four-way valve assembly 10d is part of the gas-side refrigerant circuit 10A and can be connected to the oil separator 8, the gas-side shut-off valve 18, the accumulator 7, and the outdoor heat exchanger 4. In other words, the iron-based four-way valve 3a, which constitutes the first iron-based metal component, can be positioned relative to the oil separator 8, the gas-side shut-off valve 18, the accumulator 7, and the outdoor heat exchanger 4 by incorporating the four-way valve assembly 10d. The first copper pipe 13 is pre-joined to the connection portion of the iron-based four-way valve 3a.

[0097] Furthermore, the first refrigerant piping assembly 10a is a gas-side refrigerant circuit 10A and can be connected to one or more sections between the accumulator 7 and the compressor 2, and between the compressor 2 and the oil separator 8.

[0098] In other words, the first refrigerant piping 11, which is an iron-based first metal component, can be positioned between the accumulator 7 and the compressor 2, or between the compressor 2 and the oil separator 8, by incorporating the first refrigerant piping assembly 10a. The first copper pipe 13 is pre-joined to the end of such iron-based first refrigerant piping 11. The first copper pipe 13 can be connected to the four-way valve 3 side of the header pipe 4b, etc., with respect to the outdoor heat exchanger 4.

[0099] On the other hand, the second refrigerant piping assembly 10b is a liquid-side refrigerant circuit 10B that can be connected to one or more sections between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, and between the outdoor expansion valve 5a and the liquid-side blocking valve 19.

[0100] In other words, the iron-based second refrigerant piping 12, which is an iron-based second metal component, can be positioned between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, or between the outdoor expansion valve 5a and the liquid side shutoff valve 19, by incorporating the second refrigerant piping assembly 10b. The second copper pipe 14 is pre-joined to the end of such iron-based second refrigerant piping 12. The second copper pipe 14 can be connected to the distributor 4c side of the main body 4a of the outdoor heat exchanger 4, or to the main body 4a side or the outdoor expansion valve 5a side of the distributor 4c, etc.

[0101] Furthermore, the first refrigerant piping assembly 10a and the second refrigerant piping assembly 10b can also be connected to one or more sections of the user-side refrigerant circuit 10C, specifically between the indoor heat exchanger 6 and the indoor expansion valve 5b, between the indoor expansion valve 5b and the liquid-side shutoff valve 19, and between the indoor heat exchanger 6 and the gas-side shutoff valve 18. In Figure 3, the second refrigerant piping assembly 10b is connected to these sections, but if vibration or strength is a problem in the indoor unit 200, the first refrigerant piping assembly 10a may be connected to these sections.

[0102] Furthermore, it is preferable that the length of the first copper pipe 13 along its centerline, the length of the second copper pipe 14 along its centerline, the thickness of the pipe wall of the iron-based first refrigerant pipe 11, the thickness of the pipe wall of the iron-based second refrigerant pipe 12, the thickness of the pipe wall of the first copper pipe 13, the thickness of the pipe wall of the second copper pipe 14, and the type of compressor 2 are provided in the same manner as in the air conditioner 1 described above.

[0103] In this type of air conditioner 3, the refrigerant circuit 10 is formed using refrigerant piping assemblies 10a, 10b and a four-way valve assembly 10d. After joining the copper pipe and the iron-based refrigerant piping and iron-based four-way valve in advance by furnace brazing under controlled atmosphere, the ends of the copper pipes joined to the iron-based refrigerant piping and iron-based four-way valve can be connected to existing copper-based refrigerant piping and equipment in any atmosphere, such as air. Since a portion of the refrigerant circuit 10 is replaced with iron-based refrigerant piping and equipment, it is possible to reduce material costs while making connections to existing copper-based refrigerant piping and equipment using conventional equipment and methods. Therefore, even though there are joints between dissimilar metals, the iron-based refrigerant piping and equipment are properly joined to the copper-based refrigerant piping and equipment, and a refrigeration cycle device with reduced manufacturing costs can be provided.

[0104] Furthermore, the refrigerant piping assemblies 10a, 10b and the four-way valve assembly 10d have different chemical compositions for the copper-based refrigerant piping that makes up their ends, depending on their positional relationship with the equipment that generates vibration, thereby increasing the vibration resistance of the refrigerant piping. For copper pipes connected to the compressor 2 and the four-way valve 3, which generate vibration during operation, the tensile strength and fatigue strength are enhanced by solid solution strengthening or precipitation strengthening through the addition of alloying elements. On the other hand, for copper pipes not connected to these, costs are suppressed by omitting or reducing the addition of alloying elements. Therefore, it is possible to provide a refrigeration cycle system that has high vibration resistance to the refrigerant piping, suppresses detachment and breakage of the refrigerant piping, and has reduced manufacturing costs.

[0105] <Fourth Embodiment> Figure 4 is a diagram showing a refrigerant circuit provided in a refrigeration cycle device according to a fourth embodiment of the present invention. Figure 4 shows an example of a refrigerant circuit provided in an air conditioner, which is an example of a refrigeration cycle device. As shown in Figure 4, the air conditioner 4 can also be provided in a configuration without an oil separator. Other main components of the air conditioner 4 are the same as those of the air conditioner 1 described above.

[0106] In Figure 4, the refrigerant circuit 10 is formed by connecting a compressor 2, a four-way valve 3, an outdoor heat exchanger 4 which is a heat source side heat exchanger, an outdoor expansion valve 5a which is a pressure reducer, an indoor expansion valve 5b which is a pressure reducer, an indoor heat exchanger 6 which is a heat utilization side heat exchanger, an accumulator 7, a gas side shutoff valve 18, and a liquid side shutoff valve 19 via refrigerant piping. The refrigerant circuit 10 is composed of at least a gas side refrigerant circuit 10A, a liquid side refrigerant circuit 10B, and a utilization side refrigerant circuit 10C.

[0107] As shown in Figure 4, the first refrigerant piping assembly 10a is a gas-side refrigerant circuit 10A and can be connected to one or more of the following sections: between the accumulator 7 and the compressor 2, between the compressor 2 and the four-way valve 3, between the four-way valve 3 and the gas-side shutoff valve 18, between the four-way valve 3 and the accumulator 7, and between the four-way valve 3 and the outdoor heat exchanger 4.

[0108] In other words, the first refrigerant piping 11, which is an iron-based first metal component, can be positioned between the accumulator 7 and the compressor 2, between the compressor 2 and the four-way valve 3, between the four-way valve 3 and the gas-side shutoff valve 18, between the four-way valve 3 and the accumulator 7, or between the four-way valve 3 and the outdoor heat exchanger 4 by incorporating the first refrigerant piping assembly 10a. The first copper pipe 13 is pre-joined to the end of such iron-based first refrigerant piping 11. The first copper pipe 13 can be connected to the four-way valve 3 side of the header pipe 4b, etc., with respect to the outdoor heat exchanger 4.

[0109] On the other hand, the second refrigerant piping assembly 10b is a liquid-side refrigerant circuit 10B that can be connected to one or more sections between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, and between the outdoor expansion valve 5a and the liquid-side blocking valve 19.

[0110] In other words, the iron-based second refrigerant piping 12, which is an iron-based second metal component, can be positioned between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, or between the outdoor expansion valve 5a and the liquid side shutoff valve 19, by incorporating the second refrigerant piping assembly 10b. The second copper pipe 14 is pre-joined to the end of such iron-based second refrigerant piping 12. The second copper pipe 14 can be connected to the distributor 4c side of the main body 4a of the outdoor heat exchanger 4, or to the main body 4a side or the outdoor expansion valve 5a side of the distributor 4c, etc.

[0111] Furthermore, the first refrigerant piping assembly 10a and the second refrigerant piping assembly 10b can also be connected to one or more sections of the user-side refrigerant circuit 10C, specifically between the indoor heat exchanger 6 and the indoor expansion valve 5b, between the indoor expansion valve 5b and the liquid-side shutoff valve 19, and between the indoor heat exchanger 6 and the gas-side shutoff valve 18. In Figure 4, the second refrigerant piping assembly 10b is connected to these sections, but if vibration or strength is a problem in the indoor unit 200, the first refrigerant piping assembly 10a may be connected to these sections.

[0112] Furthermore, it is preferable that the length of the first copper pipe 13 along its centerline, the length of the second copper pipe 14 along its centerline, the thickness of the pipe wall of the iron-based first refrigerant pipe 11, the thickness of the pipe wall of the iron-based second refrigerant pipe 12, the thickness of the pipe wall of the first copper pipe 13, the thickness of the pipe wall of the second copper pipe 14, and the type of compressor 2 are provided in the same manner as in the air conditioner 1 described above.

[0113] In this type of air conditioner 4, since the refrigerant circuit 10 is formed using refrigerant piping assemblies 10a and 10b, copper pipes and iron-based refrigerant piping are pre-joined by furnace brazing under controlled atmosphere, and then the ends of the copper pipes joined to the iron-based refrigerant piping can be connected to existing copper-based refrigerant piping and equipment in any atmosphere, such as air. Because a portion of the refrigerant circuit 10 is replaced with iron-based refrigerant piping, it is possible to connect to existing copper-based refrigerant piping and equipment using conventional equipment and methods, while reducing material costs. Therefore, even though there are joints between dissimilar metals, iron-based refrigerant piping and equipment are properly joined to copper-based refrigerant piping and equipment, and a refrigeration cycle device with reduced manufacturing costs can be provided.

[0114] Furthermore, the refrigerant piping assemblies 10a and 10b have different chemical compositions for the copper-based refrigerant piping that makes up their ends, depending on their position relative to the equipment that generates vibration, thereby increasing the vibration resistance of the refrigerant piping. For copper pipes connected to the compressor 2 and four-way valve 3, which generate vibration during operation, the tensile strength and fatigue strength are enhanced by solid solution strengthening or precipitation strengthening through the addition of alloying elements. On the other hand, for copper pipes not connected to these, costs are suppressed by omitting or reducing the addition of alloying elements. Therefore, it is possible to provide a refrigeration cycle system with high vibration resistance of the refrigerant piping, suppression of detachment or breakage of the refrigerant piping, and reduced manufacturing costs.

[0115] <Fifth Embodiment> Figure 5 is a diagram showing a refrigerant circuit provided in a refrigeration cycle device according to a fifth embodiment of the present invention. Figure 5 shows an example of a refrigerant circuit provided in an air conditioner, which is an example of a refrigeration cycle device. As shown in Figure 5, the air conditioner 5 can also be provided in a configuration that does not include the second refrigerant piping assembly 10b. Other main components of the air conditioner 5 are the same as those of the air conditioner 1 described above.

[0116] In Figure 5, the refrigerant circuit 10 is formed by connecting a compressor 2, a four-way valve 3, an outdoor heat exchanger 4 which is a heat source side heat exchanger, an outdoor expansion valve 5a which is a pressure reducer, an indoor expansion valve 5b which is a pressure reducer, an indoor heat exchanger 6 which is a heat utilization side heat exchanger, an accumulator 7, an oil separator 8, a gas side shutoff valve 18, and a liquid side shutoff valve 19 via refrigerant piping. The refrigerant circuit 10 is composed of at least a gas side refrigerant circuit 10A, a liquid side refrigerant circuit 10B, and a utilization side refrigerant circuit 10C.

[0117] As shown in Figure 5, the first refrigerant piping assembly 10a is a gas-side refrigerant circuit 10A and can be connected to one or more of the following sections: between the accumulator 7 and the compressor 2, between the compressor 2 and the oil separator 8, between the oil separator 8 and the four-way valve 3, between the four-way valve 3 and the gas-side shutoff valve 18, between the four-way valve 3 and the accumulator 7, and between the four-way valve 3 and the outdoor heat exchanger 4.

[0118] In other words, the first refrigerant piping 11, which is an iron-based first metal component, can be positioned between the accumulator 7 and the compressor 2, between the compressor 2 and the oil separator 8, between the oil separator 8 and the four-way valve 3, between the four-way valve 3 and the gas-side shutoff valve 18, between the four-way valve 3 and the accumulator 7, or between the four-way valve 3 and the outdoor heat exchanger 4 by incorporating the first refrigerant piping assembly 10a. The first copper pipe 13 is pre-joined to the end of such iron-based first refrigerant piping 11. The first copper pipe 13 can be connected to the four-way valve 3 side of the header pipe 4b, etc., with respect to the outdoor heat exchanger 4.

[0119] On the other hand, the second refrigerant piping assembly 10b is not connected between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, nor between the outdoor expansion valve 5a and the liquid side shutoff valve 19. Instead, copper-based refrigerant piping 15, made of copper or a copper alloy, is connected. In Figure 5, copper members 20 are joined to each piece of equipment, but the copper members 20 may be omitted.

[0120] In other words, between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, and between the outdoor expansion valve 5a and the liquid-side shutoff valve 19, a second iron-based refrigerant pipe 12 is not provided by assembly incorporation. Instead, a copper-based refrigerant pipe 15 is connected, which is made of copper that is substantially free of one or more alloying elements from Co, Sn, Zn, Ni, Zr, and Fe through active addition, or a copper-based refrigerant pipe 15 made of a copper alloy in which the content of these alloying elements is lower than that of the first copper pipe 13. The copper-based refrigerant pipe 15 can be connected to the distributor 4c side of the main body 4a of the outdoor heat exchanger 4, or to the main body 4a side or the outdoor expansion valve 5a side of the distributor 4c, etc.

[0121] These sections are primarily through which liquid refrigerant flows, making it possible to install refrigerant piping with a relatively thin profile. Furthermore, these sections are not close to the compressor 2, which generates continuous vibrations during operation, or the four-way valve 3, which generates intermittent vibrations during switching. Because the outdoor heat exchanger 4 is interposed between the compressor 2 and the four-way valve 3, vibrations from the equipment's operation are less likely to affect these sections. In such sections, there is little need to use refrigerant piping assemblies with low-cost iron-based refrigerant piping, and conventionally used phosphorus-deoxidized copper pipes or copper alloy pipes with a low alloy composition that contain fewer alloying elements and thus reduce raw material costs can be used.

[0122] Furthermore, in one or more of the following sections, between the indoor heat exchanger 6 and the indoor expansion valve 5b, between the indoor expansion valve 5b and the liquid-side shutoff valve 19, and between the indoor heat exchanger 6 and the gas-side shutoff valve 18, only the first refrigerant piping assembly 10a, the second refrigerant piping assembly 10b, or copper-based refrigerant piping 15 may be connected. In Figure 5, copper-based refrigerant piping 15 with an alloying element content lower than that of the first copper pipe 13 is connected to these sections. However, if vibration or strength is a problem in the indoor unit 200, copper-based refrigerant piping 15 containing one or more alloying elements from P, Co, Sn, Zn, Ni, Zr, and Fe may be connected to these sections.

[0123] Furthermore, it is preferable that the length of the first copper pipe 13 along the centerline, the thickness of the pipe wall of the iron-based first refrigerant piping 11, the thickness of the pipe wall of the first copper pipe 13, and the type of compressor 2 on the refrigerant circuit 10 are provided in the same manner as in the air conditioner 1 described above.

[0124] In such an air conditioner 5, the refrigerant circuit 10 is formed using a refrigerant piping assembly 10a. After joining the copper pipe and the iron-based refrigerant piping in advance by furnace brazing under controlled atmosphere, the ends of the copper pipes joined to the iron-based refrigerant piping can be connected to existing copper-based refrigerant piping and equipment in any atmosphere, such as air. Since a portion of the refrigerant circuit 10 is replaced with iron-based refrigerant piping, it is possible to connect to existing copper-based refrigerant piping and equipment using conventional equipment and methods while reducing material costs. Therefore, even though there are joints between dissimilar metals, the iron-based refrigerant piping and equipment are properly joined to the copper-based refrigerant piping and equipment, and a refrigeration cycle device with reduced manufacturing costs can be provided.

[0125] Furthermore, the refrigerant piping assembly 10a is designed to enhance the vibration resistance of the refrigerant piping because the chemical composition of the copper-based refrigerant piping constituting its ends is selected according to its positional relationship with equipment that generates vibration. The refrigerant piping assembly 10a is used in sections near the compressor 2 and four-way valve 3, which generate vibration during operation, while copper-based refrigerant piping is used in sections further away from the compressor 2 and four-way valve 3. This allows for a reduction in the overall cost of the refrigerant circuit 10, including sections with thinner refrigerant piping. Therefore, a refrigeration cycle system can be provided that offers high vibration resistance to the refrigerant piping, suppresses detachment and breakage of the refrigerant piping, and reduces manufacturing costs.

[0126] <Sixth Embodiment> Figure 6 is a diagram showing a refrigerant circuit provided in a refrigeration cycle device according to the sixth embodiment of the present invention. Figure 6 shows an example of a refrigerant circuit provided in an air conditioner, which is an example of a refrigeration cycle device. As shown in Figure 6, the air conditioner 6 is equipped with an iron-based oil separator 8a made of iron, iron alloy, or stainless steel, and can also be configured without a second refrigerant piping assembly 10b. Other main components of the air conditioner 6 are the same as those of the air conditioner 2 described above.

[0127] In Figure 6, the refrigerant circuit 10 is formed by connecting a compressor 2, a four-way valve 3, an outdoor heat exchanger 4 which is a heat source side heat exchanger, an outdoor expansion valve 5a and an indoor expansion valve 5b which are pressure reducers, an indoor heat exchanger 6 which is a utilization side heat exchanger, an accumulator 7, an iron-based oil separator 8a, a gas side shutoff valve 18, and a liquid side shutoff valve 19 via refrigerant piping. The refrigerant circuit 10 is composed of at least a gas side refrigerant circuit 10A, a liquid side refrigerant circuit 10B, and a utilization side refrigerant circuit 10C.

[0128] As shown in Figure 6, the oil separator assembly 10c is part of the gas-side refrigerant circuit 10A and can be connected between the compressor 2 and the four-way valve 3. That is, the iron-based oil separator 8a, which constitutes the first iron-based metal component, can be positioned between the compressor 2 and the four-way valve 3 by incorporating the oil separator assembly 10c. The copper-based first refrigerant piping 13 is pre-connected to the connection portion of the iron-based oil separator 8a.

[0129] Furthermore, the first refrigerant piping assembly 10a is a gas-side refrigerant circuit 10A and can be connected to one or more of the following sections: between the accumulator 7 and the compressor 2, between the four-way valve 3 and the gas-side shutoff valve 18, between the four-way valve 3 and the accumulator 7, and between the four-way valve 3 and the outdoor heat exchanger 4.

[0130] In other words, the first iron-based metal component, the first iron-based refrigerant piping 11, can be positioned between the accumulator 7 and the compressor 2, between the four-way valve 3 and the gas-side shutoff valve 18, between the four-way valve 3 and the accumulator 7, or between the four-way valve 3 and the outdoor heat exchanger 4 by incorporating the first refrigerant piping assembly 10a. The first copper pipe 13 is pre-joined to the end of such an iron-based first refrigerant piping 11. The first copper pipe 13 can be connected to the four-way valve 3 side of the header pipe 4b, etc., with respect to the outdoor heat exchanger 4.

[0131] On the other hand, the second refrigerant piping assembly 10b is not connected between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, nor between the outdoor expansion valve 5a and the liquid side shutoff valve 19. Instead, copper-based refrigerant piping 15, made of copper or a copper alloy, is connected. In Figure 6, copper members 20 are joined to each piece of equipment, but the copper members 20 may be omitted.

[0132] In other words, between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, and between the outdoor expansion valve 5a and the liquid-side shutoff valve 19, a second iron-based refrigerant pipe 12 is not provided by assembly incorporation. Instead, a copper-based refrigerant pipe 15 is connected, which is made of copper that is substantially free of one or more alloying elements from Co, Sn, Zn, Ni, Zr, and Fe through active addition, or a copper-based refrigerant pipe 15 made of a copper alloy in which the content of these alloying elements is lower than that of the first copper pipe 13. The copper-based refrigerant pipe 15 can be connected to the distributor 4c side of the main body 4a of the outdoor heat exchanger 4, or to the main body 4a side or the outdoor expansion valve 5a side of the distributor 4c, etc.

[0133] These sections are primarily through which liquid refrigerant flows, making it possible to install refrigerant piping with a relatively thin profile. Furthermore, these sections are not close to the compressor 2, which generates continuous vibrations during operation, or the four-way valve 3, which generates intermittent vibrations during switching. Because the outdoor heat exchanger 4 is interposed between the compressor 2 and the four-way valve 3, vibrations from the equipment's operation are less likely to affect these sections. In such sections, there is little need to use refrigerant piping assemblies with low-cost iron-based refrigerant piping, and conventionally used phosphorus-deoxidized copper pipes or copper alloy pipes with a low alloy composition that contain fewer alloying elements and thus reduce raw material costs can be used.

[0134] Furthermore, in one or more of the following sections, between the indoor heat exchanger 6 and the indoor expansion valve 5b, between the indoor expansion valve 5b and the liquid-side shutoff valve 19, and between the indoor heat exchanger 6 and the gas-side shutoff valve 18, only the first refrigerant piping assembly 10a, the second refrigerant piping assembly 10b, or copper-based refrigerant piping 15 may be connected. In Figure 6, copper-based refrigerant piping 15 with an alloying element content lower than that of the first copper pipe 13 is connected to these sections. However, if vibration or strength is a problem in the indoor unit 200, copper-based refrigerant piping 15 containing one or more alloying elements from P, Co, Sn, Zn, Ni, Zr, and Fe may be connected to these sections.

[0135] Furthermore, it is preferable that the length of the first copper pipe 13 along the centerline, the thickness of the pipe wall of the iron-based first refrigerant piping 11, the thickness of the pipe wall of the first copper pipe 13, and the type of compressor 2 on the refrigerant circuit 10 are provided in the same manner as in the air conditioner 1 described above.

[0136] In such an air conditioner 6, the refrigerant circuit 10 is formed using a refrigerant piping assembly 10a and an oil separator assembly 10c. After joining copper pipes and iron-based refrigerant piping or iron-based oil separators in advance by furnace brazing under controlled atmosphere, the ends of the copper pipes joined to the iron-based refrigerant piping or iron-based oil separators can be connected to existing copper-based refrigerant piping or equipment in any atmosphere, such as air. Since a portion of the refrigerant circuit 10 is replaced with iron-based refrigerant piping or equipment, it is possible to connect to existing copper-based refrigerant piping or equipment using conventional equipment and methods while reducing material costs. Therefore, even though there are joints between dissimilar metals, iron-based refrigerant piping or equipment is properly joined to copper-based refrigerant piping or equipment, and a refrigeration cycle device with reduced manufacturing costs can be provided.

[0137] Furthermore, the refrigerant piping assembly 10a and the oil separator assembly 10c have different chemical compositions for the copper-based refrigerant piping that makes up their ends, depending on their position relative to equipment that generates vibration, thereby increasing the vibration resistance of the refrigerant piping. The refrigerant piping assembly 10a is used in sections near the compressor 2 and the four-way valve 3, which generate vibration during operation, while copper-based refrigerant piping is used in sections further away from the compressor 2 and the four-way valve 3. This allows for a reduction in the overall cost of the refrigerant circuit 10, including sections where the refrigerant piping is thinner. As a result, a refrigeration cycle system can be provided that has high vibration resistance to the refrigerant piping, suppresses detachment and breakage of the refrigerant piping, and reduces manufacturing costs.

[0138] <Seventh Embodiment> Figure 7 is a diagram showing a refrigerant circuit provided in a refrigeration cycle device according to the seventh embodiment of the present invention. Figure 7 shows an example of a refrigerant circuit provided in an air conditioner, which is an example of a refrigeration cycle device. As shown in Figure 7, the air conditioner 7 is equipped with an iron-based four-way valve 3a made of iron, iron alloy, or stainless steel, and can also be configured without a second refrigerant piping assembly 10b. Other main components of the air conditioner 7 are the same as those of the air conditioner 3 described above.

[0139] In Figure 7, the refrigerant circuit 10 is formed by connecting a compressor 2, an iron-based four-way valve 3, an outdoor heat exchanger 4 which is a heat source side heat exchanger, an outdoor expansion valve 5a and an indoor expansion valve 5b which are pressure reducers, an indoor heat exchanger 6 which is a utilization side heat exchanger, an accumulator 7, an oil separator 8, a gas side shutoff valve 18, and a liquid side shutoff valve 19 via refrigerant piping. The refrigerant circuit 10 is composed of at least a gas side refrigerant circuit 10A, a liquid side refrigerant circuit 10B, and a utilization side refrigerant circuit 10C.

[0140] As shown in Figure 7, the four-way valve assembly 10d is part of the gas-side refrigerant circuit 10A and can be connected to the oil separator 8, the gas-side shut-off valve 18, the accumulator 7, and the outdoor heat exchanger 4. In other words, the iron-based four-way valve 3a, which constitutes the first iron-based metal component, can be positioned relative to the oil separator 8, the gas-side shut-off valve 18, the accumulator 7, and the outdoor heat exchanger 4 by incorporating the four-way valve assembly 10d. The first copper pipe 13 is pre-joined to the connection portion of the iron-based four-way valve 3a.

[0141] Furthermore, the first refrigerant piping assembly 10a is a gas-side refrigerant circuit 10A and can be connected to one or more sections between the accumulator 7 and the compressor 2, and between the compressor 2 and the oil separator 8.

[0142] In other words, the first refrigerant piping 11, which is an iron-based first metal component, can be positioned between the accumulator 7 and the compressor 2, or between the compressor 2 and the oil separator 8, by incorporating the first refrigerant piping assembly 10a. The first copper pipe 13 is pre-joined to the end of such iron-based first refrigerant piping 11. The first copper pipe 13 can be connected to the four-way valve 3 side of the header pipe 4b, etc., with respect to the outdoor heat exchanger 4.

[0143] On the other hand, the second refrigerant piping assembly 10b is not connected between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, nor between the outdoor expansion valve 5a and the liquid side shutoff valve 19. Instead, copper-based refrigerant piping 15, made of copper or a copper alloy, is connected. In Figure 7, copper members 20 are joined to each piece of equipment, but the copper members 20 may be omitted.

[0144] In other words, between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, and between the outdoor expansion valve 5a and the liquid-side shutoff valve 19, a second iron-based refrigerant pipe 12 is not provided by assembly incorporation. Instead, a copper-based refrigerant pipe 15 is connected, which is made of copper that is substantially free of one or more alloying elements from Co, Sn, Zn, Ni, Zr, and Fe through active addition, or a copper-based refrigerant pipe 15 made of a copper alloy in which the content of these alloying elements is lower than that of the first copper pipe 13. The copper-based refrigerant pipe 15 can be connected to the distributor 4c side of the main body 4a of the outdoor heat exchanger 4, or to the main body 4a side or the outdoor expansion valve 5a side of the distributor 4c, etc.

[0145] These sections are primarily through which liquid refrigerant flows, making it possible to install refrigerant piping with a relatively thin profile. Furthermore, these sections are not close to the compressor 2, which generates continuous vibrations during operation, or the four-way valve 3, which generates intermittent vibrations during switching. Because the outdoor heat exchanger 4 is interposed between the compressor 2 and the four-way valve 3, vibrations from the equipment's operation are less likely to affect these sections. In such sections, there is little need to use refrigerant piping assemblies with low-cost iron-based refrigerant piping, and conventionally used phosphorus-deoxidized copper pipes or copper alloy pipes with a low alloy composition that contain fewer alloying elements and thus reduce raw material costs can be used.

[0146] Furthermore, in one or more of the following sections, between the indoor heat exchanger 6 and the indoor expansion valve 5b, between the indoor expansion valve 5b and the liquid-side shutoff valve 19, and between the indoor heat exchanger 6 and the gas-side shutoff valve 18, only the first refrigerant piping assembly 10a, the second refrigerant piping assembly 10b, or copper-based refrigerant piping 15 may be connected. In Figure 7, copper-based refrigerant piping 15 with an alloying element content lower than that of the first copper pipe 13 is connected to these sections. However, if vibration or strength is a problem in the indoor unit 200, copper-based refrigerant piping 15 containing one or more alloying elements from P, Co, Sn, Zn, Ni, Zr, and Fe may be connected to these sections.

[0147] Furthermore, it is preferable that the length of the first copper pipe 13 along the centerline, the thickness of the pipe wall of the iron-based first refrigerant piping 11, the thickness of the pipe wall of the first copper pipe 13, and the type of compressor 2 on the refrigerant circuit 10 are provided in the same manner as in the air conditioner 1 described above.

[0148] In such an air conditioner 7, the refrigerant circuit 10 is formed using a refrigerant piping assembly 10a and a four-way valve assembly 10d. After joining the copper pipe and the iron-based refrigerant piping and iron-based four-way valve in advance by furnace brazing under controlled atmosphere, the ends of the copper pipes joined to the iron-based refrigerant piping and iron-based four-way valve can be connected to existing copper-based refrigerant piping and equipment in any atmosphere, such as air. Since a portion of the refrigerant circuit 10 is replaced with iron-based refrigerant piping and equipment, it is possible to reduce material costs while making connections to existing copper-based refrigerant piping and equipment using conventional equipment and methods. Therefore, even though there are joints between dissimilar metals, iron-based refrigerant piping and equipment are properly joined to copper-based refrigerant piping and equipment, and a refrigeration cycle device with reduced manufacturing costs can be provided.

[0149] Furthermore, the refrigerant piping assembly 10a and the four-way valve assembly 10d have different chemical compositions for the copper-based refrigerant piping that makes up their ends, depending on their position relative to equipment that generates vibration, thereby increasing the vibration resistance of the refrigerant piping. The refrigerant piping assembly 10a is used in sections near the compressor 2 and the four-way valve 3, which generate vibration during operation, while copper-based refrigerant piping is used in sections further away from the compressor 2 and the four-way valve 3. This allows for a reduction in the overall cost of the refrigerant circuit 10, including sections where the refrigerant piping is thinner. As a result, a refrigeration cycle system can be provided that has high vibration resistance to the refrigerant piping, suppresses detachment and breakage of the refrigerant piping, and reduces manufacturing costs.

[0150] <Eighth Embodiment> Figure 8 is a diagram showing a refrigerant circuit provided in a refrigeration cycle device according to the eighth embodiment of the present invention. Figure 8 shows an example of a refrigerant circuit provided in an air conditioner, which is an example of a refrigeration cycle device. As shown in Figure 8, the air conditioner 8 can also be provided in a configuration that does not include an oil separator and a second refrigerant piping assembly 10b. Other main components of the air conditioner 8 are the same as those of the air conditioner 4 described above.

[0151] In Figure 8, the refrigerant circuit 10 is formed by connecting a compressor 2, a four-way valve 3, an outdoor heat exchanger 4 which is a heat source side heat exchanger, an outdoor expansion valve 5a which is a pressure reducer, an indoor expansion valve 5b which is a pressure reducer, an indoor heat exchanger 6 which is a heat utilization side heat exchanger, an accumulator 7, an oil separator 8, a gas side shutoff valve 18, and a liquid side shutoff valve 19 via refrigerant piping. The refrigerant circuit 10 is composed of at least a gas side refrigerant circuit 10A, a liquid side refrigerant circuit 10B, and a utilization side refrigerant circuit 10C.

[0152] As shown in Figure 8, the first refrigerant piping assembly 10a is a gas-side refrigerant circuit 10A and can be connected to one or more of the following sections: between the accumulator 7 and the compressor 2, between the compressor 2 and the four-way valve 3, between the four-way valve 3 and the gas-side shutoff valve 18, between the four-way valve 3 and the accumulator 7, and between the four-way valve 3 and the outdoor heat exchanger 4.

[0153] In other words, the first refrigerant piping 11, which is an iron-based first metal component, can be positioned between the accumulator 7 and the compressor 2, between the compressor 2 and the four-way valve 3, between the four-way valve 3 and the gas-side shutoff valve 18, between the four-way valve 3 and the accumulator 7, or between the four-way valve 3 and the outdoor heat exchanger 4 by incorporating the first refrigerant piping assembly 10a. The first copper pipe 13 is pre-joined to the end of such iron-based first refrigerant piping 11. The first copper pipe 13 can be connected to the four-way valve 3 side of the header pipe 4b, etc., with respect to the outdoor heat exchanger 4.

[0154] On the other hand, the second refrigerant piping assembly 10b is not connected between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, nor between the outdoor expansion valve 5a and the liquid side shutoff valve 19. Instead, copper-based refrigerant piping 15, made of copper or a copper alloy, is connected. In Figure 8, copper members 20 are joined to each piece of equipment, but the copper members 20 may be omitted.

[0155] In other words, between the outdoor heat exchanger 4 and the outdoor expansion valve 5a, and between the outdoor expansion valve 5a and the liquid-side shutoff valve 19, a second iron-based refrigerant pipe 12 is not provided by assembly incorporation. Instead, a copper-based refrigerant pipe 15 is connected, which is made of copper that is substantially free of one or more alloying elements from Co, Sn, Zn, Ni, Zr, and Fe through active addition, or a copper-based refrigerant pipe 15 made of a copper alloy in which the content of these alloying elements is lower than that of the first copper pipe 13. The copper-based refrigerant pipe 15 can be connected to the distributor 4c side of the main body 4a of the outdoor heat exchanger 4, or to the main body 4a side or the outdoor expansion valve 5a side of the distributor 4c, etc.

[0156] These sections are primarily through which liquid refrigerant flows, making it possible to install refrigerant piping with a relatively thin profile. Furthermore, these sections are not close to the compressor 2, which generates continuous vibrations during operation, or the four-way valve 3, which generates intermittent vibrations during switching. Because the outdoor heat exchanger 4 is interposed between the compressor 2 and the four-way valve 3, vibrations from the equipment's operation are less likely to affect these sections. In such sections, there is little need to use refrigerant piping assemblies with low-cost iron-based refrigerant piping, and conventionally used phosphorus-deoxidized copper pipes or copper alloy pipes with a low alloy composition that contain fewer alloying elements and thus reduce raw material costs can be used.

[0157] Furthermore, in one or more of the following sections, between the indoor heat exchanger 6 and the indoor expansion valve 5b, between the indoor expansion valve 5b and the liquid-side shutoff valve 19, and between the indoor heat exchanger 6 and the gas-side shutoff valve 18, only the first refrigerant piping assembly 10a, the second refrigerant piping assembly 10b, or copper-based refrigerant piping 15 may be connected. In Figure 8, copper-based refrigerant piping 15 with an alloying element content lower than that of the first copper pipe 13 is connected to these sections. However, if vibration or strength is a problem in the indoor unit 200, copper-based refrigerant piping 15 containing one or more alloying elements from P, Co, Sn, Zn, Ni, Zr, and Fe may be connected to these sections.

[0158] Furthermore, it is preferable that the length of the first copper pipe 13 along the centerline, the thickness of the pipe wall of the iron-based first refrigerant piping 11, the thickness of the pipe wall of the first copper pipe 13, and the type of compressor 2 on the refrigerant circuit 10 are provided in the same manner as in the air conditioner 1 described above.

[0159] In such an air conditioner 8, the refrigerant circuit 10 is formed using a refrigerant piping assembly 10a. After joining the copper pipe and the iron-based refrigerant piping in advance by furnace brazing under controlled atmosphere, the ends of the copper pipes joined to the iron-based refrigerant piping can be connected to existing copper-based refrigerant piping and equipment in any atmosphere, such as air. Since a portion of the refrigerant circuit 10 is replaced with iron-based refrigerant piping, it is possible to connect to existing copper-based refrigerant piping and equipment using conventional equipment and methods while reducing material costs. Therefore, even though there are joints between dissimilar metals, the iron-based refrigerant piping and equipment are properly joined to the copper-based refrigerant piping and equipment, and a refrigeration cycle device with reduced manufacturing costs can be provided.

[0160] Furthermore, the refrigerant piping assembly 10a is designed to enhance the vibration resistance of the refrigerant piping because the chemical composition of the copper-based refrigerant piping constituting its ends is selected according to its positional relationship with equipment that generates vibration. The refrigerant piping assembly 10a is used in sections near the compressor 2 and four-way valve 3, which generate vibration during operation, while copper-based refrigerant piping is used in sections further away from the compressor 2 and four-way valve 3. This allows for a reduction in the overall cost of the refrigerant circuit 10, including sections with thinner refrigerant piping. Therefore, a refrigeration cycle system can be provided that offers high vibration resistance to the refrigerant piping, suppresses detachment and breakage of the refrigerant piping, and reduces manufacturing costs.

[0161] Next, the results of measuring the bending fatigue of copper pipes joined to metal components, according to the bending fatigue test method specified in JIS Z 2273, are shown.

[0162] Figure 9 is an S / N diagram showing the results of a bending fatigue test. The S / N diagram in Figure 9 shows the number of cycles required to break the copper pipe under a predetermined repeated stress. The outer diameter, wall thickness, and length of each pipe in Examples 1 and 2 and Comparative Examples 1 and 2 are all the same.

[0163] The copper tube in Example 1 is formed from a copper alloy with the material symbol C5010T-O and heated to a temperature equivalent to that of furnace brazing. For example, the copper tube in Example 1 is heated for 20 to 30 minutes in a furnace with a furnace temperature of 1000°C to 1100°C.

[0164] The copper tube in Example 2 was formed from a copper alloy with the material symbol C1862T-O and heated under the same conditions as in Example 1.

[0165] The copper tube of Comparative Example 1 was made of standard copper with the material symbol C1220T-O. The copper tube of Comparative Example 2 was made of standard copper with the material symbol C1220T-O and heated under the same conditions as in Examples 1 and 2.

[0166] As shown in Figure 9, the copper tubes of Example 1 and Example 2 have a repeating count of 1.0 × 10⁻⁶. n Even in this case, the stress at fracture is higher than the allowable stress σ1. Therefore, it was found that the copper tubes of Example 1 and Example 2 do not have strength issues even when heated by furnace brazing.

[0167] Furthermore, it was found that the copper pipes of Example 1 and Example 2 showed less decrease in strength with increasing number of repetitions compared to the copper pipes of Comparative Example 1 and Comparative Example 2. n In this test, it was found that the strength of the copper pipe in Example 1 was close to that of the copper pipe in Comparative Example 2, which was not heated.

[0168] Next, we will describe an example of the structure of the joint between iron-based refrigerant piping and copper pipes that form a refrigerant piping assembly.

[0169] Figure 10 shows an example of a joint between an iron-based refrigerant pipe and a copper pipe. Figure 10 shows the structure of a joint in which the end of an iron-based refrigerant pipe 11, which is a metal member, and the end of a copper member 20, which is different from the first and second metal members, are connected via a first copper pipe 13. The copper member 20 may be the end of a copper-based refrigerant pipe that forms a refrigerant circuit 10, or the end of a connection part of equipment that performs a refrigeration cycle.

[0170] As shown in Figure 10, the iron-based first refrigerant piping 11, which is an iron-based first metal component, can be connected to the copper component 20 that forms the refrigerant circuit 10 via the first copper pipe 13. The copper component 20 is made of copper that is substantially free of one or more alloying elements from Co, Sn, Zn, Ni, Zr, and Fe through active addition, or of a copper alloy in which the content of these alloying elements is lower than that of the first copper pipe 13. For example, conventionally used phosphorus-deoxidized copper pipes or copper alloy pipes with a low alloy composition that have fewer alloying elements and thus reduce raw material costs can be used.

[0171] It is preferable that an enlarged diameter portion 11a is formed at the end of the iron-based refrigerant piping 11, with both the inner and outer diameters being larger than those of the main body. It is also preferable that an inner flange 13a is formed at the end of the first copper pipe 13, projecting toward the center in a flange-like manner. It is preferable that the length of the first copper pipe 13 along the centerline be shorter than the length of the iron-based first refrigerant piping 11 or the copper member 20 along the centerline.

[0172] Furthermore, it is preferable that the outer diameter of the first copper pipe 13 be smaller than the inner diameter of the enlarged portion 11a of the iron-based refrigerant piping 11. It is also preferable that the inner diameter of the first copper pipe 13 be larger than the outer diameter of the copper member 20. Using such a first copper pipe 13, the first copper pipe 13 can be fitted inside the enlarged portion 11a of the iron-based refrigerant piping 11. In addition, the end of the copper member 20 can be fitted inside the first copper pipe 13.

[0173] It is preferable that the iron-based first refrigerant piping 11 and the copper member 20 are connected so as to overlap via the first copper pipe 13. With this structure, even if the length of the first copper pipe 13 is shortened, the iron-based first refrigerant piping 11 and the copper member 20 can be joined with high strength. The iron-based first refrigerant piping 11 and the first copper pipe 13 are brazed in a furnace. The first copper pipe 13 joined to the iron-based first refrigerant piping 11 and the copper member 20 can be joined by brazing in air or the like. Since the length of the first copper pipe 13 can be shortened, the manufacturing cost of the refrigeration cycle device can be further reduced.

[0174] Furthermore, the structure of the joint between the iron-based refrigerant piping and the copper pipe shown in Figure 10 can also be formed in the iron-based oil separator 8a or the iron-based four-way valve 3a. Such a structure may be formed in some of the joints of the refrigerant circuit 10, or it may be formed in all of the joints of the refrigerant circuit 10.

[0175] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are included as long as they do not depart from the technical scope. For example, the embodiments described above are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace some of the configurations of one embodiment with other configurations, or to add other configurations to the configuration of one embodiment. It is also possible to add other configurations, delete configurations, or substitute configurations for some of the configurations of one embodiment.

[0176] For example, in the above embodiment, the refrigerant circuit 10 may also be equipped with a receiver, a dryer, etc. The receiver, dryer, etc. constitute a metal member to which an assembly can be connected. The refrigerant circuit 10 may also be equipped with an injection circuit for injecting refrigerant at an intermediate pressure into the compressor 2. The injection circuit is connected to the compressor 2, bypassing the evaporator from the condenser. The injection circuit may be formed by an assembly.

[0177] Furthermore, in the above embodiment, an air conditioner is shown as an example of a refrigeration cycle device, but the air conditioner may be any of the following: a room air conditioner, a package air conditioner, a household multi-split air conditioner, a commercial air conditioner, a commercial multi-split air conditioner, a building multi-split air conditioner, etc. In each figure, the outdoor unit 100 and the indoor unit 200 are connected one-to-one, but multiple outdoor units may be connected to one indoor unit, multiple indoor units may be connected to one outdoor unit, or multiple indoor units may be connected to multiple outdoor units.

[0178] Furthermore, although an air conditioner is shown as an example of a refrigeration cycle device in the above embodiment, a refrigeration device may also be a chiller, refrigerator, freezer, or refrigerator-freezer. The configuration of the assembly according to the above embodiment can be applied to the refrigerant circuit of a refrigeration device equipped with an outdoor unit. The refrigerant circuit of a refrigeration device is formed by connecting a compressor, a heat source side heat exchanger located outside the storage unit, a pressure reducer such as a capillary, a gas side shut-off valve, a liquid side shut-off valve, a utilization side heat exchanger located inside the storage unit, etc., via refrigerant piping.

[0179] In refrigeration equipment, first metal components include a three-way valve, an accumulator, an oil separator, and refrigerant piping that forms a gas-side refrigerant circuit connecting the gas-side shutoff valve and the heat source-side heat exchanger. Second metal components include a pressure reducer and refrigerant piping that forms a liquid-side refrigerant circuit connecting the heat source-side heat exchanger and the liquid-side shutoff valve. [Explanation of Symbols]

[0180] 1. Air conditioner 2 Compressor 3. Four-way valve 3a Iron-based four-way valve 4 Outdoor heat exchanger 5a Outdoor expansion valve 5b Indoor expansion valve 6 Indoor heat exchanger 7. Accumulator 8 Oil Separator 8a Iron-based oil separator 10 Refrigerant Circuit 11. Iron-based first refrigerant piping 12. Iron-based second refrigerant piping 13 No. 1 copper tube 14 Second copper tube 15. Copper-based refrigerant piping 16 Outdoor ventilation fan 17 Indoor ventilation fan 18. Gas-side shutoff valve 19 Liquid-side blocking valve 20 Copper parts

Claims

1. An outdoor unit of a refrigeration cycle system, comprising a compressor, a heat source side heat exchanger, a pressure reducer, a gas side shutoff valve, and a liquid side shutoff valve, A first metal member is arranged in the gas-side refrigerant circuit that connects the gas-side shutoff valve and the heat source-side heat exchanger via at least the compressor, A second metal member is arranged in the liquid-side refrigerant circuit that connects the heat source-side heat exchanger and the liquid-side blocking valve via at least the pressure reducer, A first copper pipe joined to the first metal member, The present invention comprises a second copper pipe joined to the second metal member, The first metal member and the second metal member are made of iron, an iron alloy, or stainless steel. The first copper tube is made of a copper alloy containing alloying elements, The outdoor unit of a refrigeration cycle device, wherein the second copper pipe is made of copper that does not contain the alloying element, or a copper alloy in which the content of the alloying element is lower than that of the first copper pipe.

2. An outdoor unit of a refrigeration cycle device according to claim 1, The first metal component is a refrigerant pipe, an oil separator, a part of an oil separator, a four-way valve, or a part of a four-way valve. The second metal component is the outdoor unit of the refrigeration cycle system, which is a refrigerant pipe.

3. An outdoor unit of a refrigeration cycle system comprising a compressor, a heat source side heat exchanger, a pressure reducer, a gas side shutoff valve, and a liquid side shutoff valve, A first metal member is arranged in the gas-side refrigerant circuit that connects the gas-side shutoff valve and the heat source-side heat exchanger via at least the compressor, A refrigerant piping arranged in the liquid-side refrigerant circuit that connects the heat source-side heat exchanger and the liquid-side shutoff valve via at least the pressure reducer, The first copper pipe is joined to the first metal member, The first metal member is made of iron, an iron alloy, or stainless steel. The first copper tube is made of a copper alloy containing alloying elements, The outdoor unit of a refrigeration cycle device, wherein the refrigerant piping is made of copper that does not contain the alloying element, or a copper alloy in which the content of the alloying element is lower than that of the first copper pipe.

4. An outdoor unit of a refrigeration cycle device according to claim 3, The first metal component is a refrigerant pipe, an oil separator, a metal component that constitutes part of the oil separator, a four-way valve, or a metal component that constitutes part of the four-way valve, and is an outdoor unit of a refrigeration cycle system.

5. An outdoor unit of a refrigeration cycle device according to any one of claims 1 to 4, The aforementioned alloying element is one or more of P, Co, Sn, Zn, Ni, Zr, and Fe, in the outdoor unit of a refrigeration cycle device.

6. An outdoor unit of a refrigeration cycle device according to claim 1 or claim 3, The first copper pipe is an outdoor unit of a refrigeration cycle device that is shorter than the refrigerant piping connected to the first copper pipe.

7. An outdoor unit of a refrigeration cycle device according to claim 1 or claim 3, The first metal member is a refrigerant pipe, The outdoor unit of the refrigeration cycle device wherein the thickness of the first copper pipe is greater than the thickness of the refrigerant piping, which is the first metal component.

8. An outdoor unit of a refrigeration cycle device according to claim 1 or claim 3, The first metal member is a refrigerant pipe, The second metal member is a refrigerant pipe, The outdoor unit of a refrigeration cycle device wherein the thickness of the first copper pipe is greater than the thickness of the refrigerant piping, which is the first metal member, and the thickness of the refrigerant piping, which is the second metal member.

9. An outdoor unit of a refrigeration cycle device according to claim 1 or claim 3, It comprises one or more of the following: an accumulator, an oil separator, and a four-way valve. The first metal member is a refrigerant pipe connected between the compressor and the accumulator, between the compressor and the oil separator, or between the compressor and the four-way valve. The compressor is an outdoor unit of a refrigeration cycle system, which is either a scroll compressor or a twin rotary compressor.

10. An outdoor unit of a refrigeration cycle device according to any one of claims 1 to 4, An outdoor unit of a refrigeration cycle device in which the content of the alloying element in the first copper pipe is lower than the content of the alloying element in the first metal member.

11. An outdoor unit of a refrigeration cycle device according to claim 1 or claim 3, The first metal member is a refrigerant pipe, The first copper pipe is connected to the copper member that forms the refrigerant circuit. The copper component is made of copper that does not contain the alloying element, or a copper alloy in which the content of the alloying element is lower than that of the first copper pipe, in the outdoor unit of the refrigeration cycle device.

12. An outdoor unit of a refrigeration cycle device according to claim 11, The outdoor unit of the refrigeration cycle device in which the refrigerant piping and the copper member overlap via the first copper pipe.

13. A refrigeration cycle system comprising an outdoor unit having a compressor, a heat source side heat exchanger, a pressure reducer, a gas side shutoff valve and a liquid side shutoff valve, and an indoor unit, A first metal member is arranged in the gas-side refrigerant circuit that connects the gas-side shutoff valve and the heat source-side heat exchanger via at least the compressor, A second metal member is arranged in the liquid-side refrigerant circuit, which connects the heat source-side heat exchanger and the liquid-side shutoff valve via at least the pressure reducer, or in the utilization-side refrigerant circuit, which is a refrigerant circuit built into the indoor unit, A first copper pipe joined to the first metal member, The present invention comprises a second copper pipe joined to the second metal member, The first metal member and the second metal member are made of iron, an iron alloy, or stainless steel. The first copper tube is made of a copper alloy containing alloying elements, The refrigeration cycle device wherein the second copper tube is made of copper that does not contain the alloying element, or a copper alloy in which the content of the alloying element is lower than that of the first copper tube.

14. A refrigeration cycle system comprising an outdoor unit having a compressor, a heat source side heat exchanger, a pressure reducer, a gas side shutoff valve, and a liquid side shutoff valve, and an indoor unit, A first metal member is arranged in the gas-side refrigerant circuit that connects the gas-side shutoff valve and the heat source-side heat exchanger via at least the compressor, A liquid-side refrigerant circuit connecting the heat source-side heat exchanger and the liquid-side shutoff valve via at least the pressure reducer, or a refrigerant piping arranged in the utilization-side refrigerant circuit which is a refrigerant circuit built into the indoor unit, The first copper pipe is joined to the first metal member, The first metal member is made of iron, an iron alloy, or stainless steel. The first copper tube is made of a copper alloy containing alloying elements, The refrigeration cycle device wherein the refrigerant piping is made of copper that does not contain the alloying element, or a copper alloy in which the content of the alloying element is lower than that of the first copper pipe.

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