air conditioner

Abstract

The present invention provides an air conditioner that can suppress galvanic corrosion at a connection between an aluminum refrigerant pipe and a metal refrigerant pipe having a low ionization tendency over a long period of time while reducing the manufacturing cost of the refrigerant circuit and ensuring freedom in design of the refrigerant circuit. The air conditioner includes a connection part (13b) in which an aluminum refrigerant pipe (11b) made of aluminum or a metal containing aluminum is connected to a metal refrigerant pipe (12b) made of a metal having a lower ionization tendency than aluminum, and the outer surface of the connection part (13b) is covered with a cover (20), and a sacrificial corrosion protection layer is formed on the outer surface of the aluminum refrigerant pipe (11b).

Description

[Technical Field]

[0001] The present invention relates to an air conditioner having a connection part in which an aluminum refrigerant pipe and a metal refrigerant pipe made of a metal having a lower ionization tendency than aluminum are connected. [Background technology]

[0002] Air conditioners are equipped with a refrigerant circuit that circulates a refrigerant to perform a refrigeration cycle. The refrigerant circuit is formed by connecting devices such as a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger via refrigerant pipes. Traditionally, refrigerant pipes in air conditioners and heat transfer pipes in heat exchangers have been made of copper, such as phosphorus-deoxidized copper. However, in recent years, there has been a shift to using aluminum for the devices and refrigerant pipes that make up the refrigerant circuit.

[0003] Converting equipment and refrigerant pipes to aluminum can reduce material costs and make the equipment lighter. However, it is expected that traditional copper refrigerant pipes and aluminum refrigerant pipes will coexist. The joints connecting aluminum and copper refrigerant pipes are dissimilar metals, which creates a problem of susceptibility to galvanic corrosion.

[0004] When water droplets form on the connection due to condensation or other reasons, a local battery is formed between the aluminum and copper. Furthermore, when water droplets adhere to copper refrigerant pipes, copper ions are eluted into the droplets, and the droplets containing copper ions travel down the copper refrigerant pipe and adhere to the aluminum refrigerant pipe. These phenomena cause galvanic corrosion, which can lead to gaps and holes in the connection and pipe walls, resulting in refrigerant leakage.

[0005] Patent Document 1 describes a technology for preventing corrosion of aluminum refrigerant pipes connected to copper refrigerant pipes. This technology involves providing an inverted U-shaped section, where the aluminum refrigerant pipe has a convex shape on the upper side, or a U-shaped section, where the copper refrigerant pipe has a convex shape on the lower side, near the connection between the aluminum refrigerant pipe and the copper refrigerant pipe. The inverted U-shaped section or U-shaped section prevents moisture adhering to the copper refrigerant pipe from moving to the aluminum refrigerant pipe. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5853203 Summary of the Invention [Problem to be solved by the invention]

[0007] In refrigeration and air conditioning equipment such as air conditioners, aluminum refrigerant pipes made of aluminum or a metal containing aluminum may be connected to metal refrigerant pipes made of a metal with a lower ionization tendency than aluminum, such as copper refrigerant pipes or stainless steel refrigerant pipes. Therefore, more practical measures are needed to prevent galvanic corrosion at connections between aluminum refrigerant pipes and metal refrigerant pipes with a lower ionization tendency.

[0008] As in Patent Document 1, placing aluminum refrigerant pipes on top and copper refrigerant pipes on the bottom can prevent water droplets from flowing down into the aluminum refrigerant pipes and prevent local battery formation at the connections. However, this method has the problem of restricting the placement and shape of the refrigerant pipes. The increased number of U-shaped return bends makes it difficult to secure space for arranging the refrigerant pipes. Furthermore, this method increases the manufacturing cost of the refrigerant circuit and the size of the refrigerant circuit.

[0009] One way to prevent galvanic corrosion in aluminum refrigerant pipes and in joints where aluminum refrigerant pipes are connected to metal refrigerant pipes is to cover the joints and the aluminum refrigerant pipes. Covering the joints and the aluminum refrigerant pipes with a covering material such as a tube can prevent the adhesion of water droplets due to condensation. However, if the length of the covering material is long, the covering process requires more labor, which increases manufacturing costs.

[0010] Therefore, the present invention aims to provide an air conditioner that can suppress galvanic corrosion at the connection between an aluminum refrigerant pipe and a metal refrigerant pipe with a low ionization tendency over a long period of time, while reducing the manufacturing costs of the refrigerant circuit and ensuring freedom in designing the refrigerant circuit. [Means for solving the problem]

[0011] In order to solve the above problems, the air conditioner according to the present invention includes a connection part where an aluminum refrigerant pipe made of aluminum or a metal containing aluminum is connected so as to be positioned vertically lower than a metal refrigerant pipe made of a metal having a lower ionization tendency than aluminum, the outer surface of the connection part is covered with a cover, and a sacrificial anticorrosion layer is formed on the outer surface of the aluminum refrigerant pipe. The surface area of ​​the aluminum refrigerant pipe is larger than the surface area of ​​the metal refrigerant pipe. . [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an air conditioner that can suppress galvanic corrosion at the connection between an aluminum refrigerant pipe and a metal refrigerant pipe with a low ionization tendency over a long period of time, while reducing the manufacturing costs of the refrigerant circuit and ensuring freedom in designing the refrigerant circuit. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of an air conditioner. [Figure 2] FIG. 2 is a diagram illustrating an example of a refrigerant circuit included in the air conditioner. [Figure 3] FIG. 2 is a diagram illustrating the internal configuration of the outdoor unit of the air conditioner. [Figure 4] 10A and 10B are diagrams illustrating the structure of a connection portion in a conventional air conditioner. [Figure 5] 3A and 3B are diagrams illustrating the structure of a connection portion in an air conditioner according to an embodiment of the present invention. [Figure 6] 1 is a diagram illustrating the structure of a refrigerant pipe connected between an outdoor heat exchanger and an expansion valve in an air conditioner according to an embodiment of the present invention. [Figure 7]1 is a diagram illustrating the structure of a refrigerant pipe connected between an expansion valve and an outdoor heat exchanger in an air conditioner according to an embodiment of the present invention. FIG. [Figure 8] 1 is a diagram illustrating the structure of a refrigerant pipe connected between an outdoor heat exchanger and a liquid-side service valve in an air conditioner according to an embodiment of the present invention. FIG. [Figure 9] 1 is a diagram illustrating the structure of a refrigerant pipe connected between a four-way valve and an outdoor heat exchanger in an air conditioner according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] An air conditioner according to one embodiment of the present invention will be described below. Note that common components in the following drawings will be assigned the same reference numerals, and duplicated explanations will be omitted. In the following description, a room air conditioner will be used as an example to illustrate the main components of the air conditioner and the configuration for suppressing galvanic corrosion.

[0015] FIG. 1 is a diagram showing an example of the configuration of an air conditioner. As shown in FIG. 1, the air conditioner 1 comprises an outdoor unit 100 that is installed outdoors, and an indoor unit 200 that is installed on a wall or the like inside a room. The outdoor unit 100 and the indoor unit 200 are connected to each other via connecting piping 300. A remote control 400 is also provided as a separate unit. Refrigerant pipes and electrical wiring run through the connecting piping 300. The remote control 400 is operated by a user to send operation signals to the indoor unit 200 for operation.

[0016] The air conditioner 1 is a device that adjusts the temperature and humidity of a space by blowing out heated air, cooled air, dehumidified air, etc. A refrigerant circulates between the outdoor unit 100 and the indoor unit 200 through refrigerant pipes. In the outdoor unit 100, heat exchange occurs between the refrigerant and outside air. In the indoor unit 200, heat exchange occurs between the refrigerant and indoor air. The indoor unit 200 adjusts the temperature and humidity of the room by exchanging heat between the refrigerant and the air drawn in from the room.

[0017] Fig. 2 is a diagram showing an example of a refrigerant circuit provided in an air conditioner. As shown in Fig. 2, the air conditioner 1 is provided with a refrigerant circuit 10 that constitutes a heat pump. The refrigerant circuit 10 executes a refrigeration cycle for cooling operation, heating operation, dehumidification operation, etc. The refrigerant circuit 10 is provided with devices such as a compressor 2, a four-way valve 3, an outdoor heat exchanger 4, an expansion valve 5, an indoor heat exchanger 6, and an accumulator 7.

[0018] These devices are connected to each other via refrigerant pipes that allow the refrigerant to flow. A liquid pipe, which is a refrigerant pipe, is connected to the outdoor unit 100 and the indoor unit 200 via a liquid-side service valve 18, and a gas pipe, which is a refrigerant pipe, is connected via a gas-side service 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.

[0019] A refrigerant is charged into the refrigerant circuit 10 when the air conditioner 1 is installed or during maintenance. The refrigerant circulates through the refrigerant circuit 10 and exchanges heat with indoor air or outdoor air for cooling operation, heating operation, dehumidification operation, etc. The outdoor unit 100 houses a compressor 2, a four-way valve 3, an outdoor heat exchanger 4, an expansion valve 5, an accumulator 7, and an outdoor blower fan 8. The indoor unit 200 houses an indoor heat exchanger 6 and an indoor blower fan 9.

[0020] The compressor 2 is a device that compresses a refrigerant, sucking in a low-pressure gas refrigerant, adiabatically compressing the gas refrigerant, and discharging the high-pressure gas refrigerant. The compressor 2 may be configured to variably control the amount of refrigerant circulated by inverter control. The compressor 2 may be a hermetic electric compressor of any suitable type, such as a scroll type, piston type, rotary type, screw type, or centrifugal type.

[0021] 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 depending on the operation mode, such as cooling operation or heating operation. The four-way valve 3 switches the circulation direction in the refrigerant circuit 10 of the refrigerant discharged from the compressor 2. In Fig. 2, the solid arrow indicates the circulation direction of the refrigerant during cooling operation. The dashed arrow indicates the circulation direction of the refrigerant during heating operation.

[0022] The outdoor heat exchanger 4 is a heat exchanger that exchanges heat between the refrigerant and outside air, and functions as a condenser during cooling operation and as an evaporator during heating operation. The outdoor blower fan 8 blows outside air into the outdoor heat exchanger 4 to promote heat exchange. The outdoor blower fan 8 is composed of a propeller fan. The expansion valve 5 is an electronically controlled valve whose opening can be adjusted, and functions as a pressure reducer that expands the refrigerant.

[0023] In FIG. 2, the outdoor heat exchanger 4 includes a main body 4a and a subcooler 4b. The heat transfer tubes of the main body 4a and the heat transfer tubes of the subcooler 4b are connected via an expansion valve 5 and a refrigerant pipe. The subcooler 4b cools the liquid refrigerant introduced into the expansion valve 5 during cooling operation. Cooling performance is improved by pre-cooling the liquid refrigerant. The subcooler 4b can also function as a hot pipe to prevent frost formation on the main body 4a during heating operation.

[0024] The indoor heat exchanger 6 is a heat exchanger that exchanges heat between the refrigerant and the indoor air, and functions as an evaporator during cooling operation and as a condenser during heating operation. The indoor blower fan 9 blows air into the indoor heat exchanger 6 to promote heat exchange, and also blows the air that has exchanged heat with the refrigerant into the room. The indoor blower fan 9 is composed of a cylindrical cross-flow fan.

[0025] The accumulator 7 is a tank-shaped device that separates gas refrigerant from liquid refrigerant, and separates and stores the liquid refrigerant contained in the gas refrigerant. By removing the liquid refrigerant that has not completely evaporated from the gas refrigerant on the suction side of the compressor 2, liquid compression in the compressor 2, which can cause abnormal noise and malfunction, is prevented.

[0026] Cooling operation of the air conditioner 1 is performed as follows. High-temperature, high-pressure gas refrigerant is adiabatically compressed in the compressor 2 and sent to the outdoor heat exchanger 4 through the four-way valve 3. The high-temperature, high-pressure gas refrigerant is condensed into liquid refrigerant through heat exchange with outside air in the outdoor heat exchanger 4, which functions as a condenser. The liquid refrigerant is pre-cooled in the sub-cooler 4b before being introduced into the expansion valve 5. The liquid refrigerant is decompressed and expanded in the expansion valve 5, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant containing a small amount of gas refrigerant.

[0027] The low-temperature, low-pressure, two-phase gas-liquid refrigerant is sent to the indoor heat exchanger 6. The two-phase gas-liquid refrigerant evaporates through heat exchange with the indoor air in the indoor heat exchanger 6, which functions as an evaporator, and becomes a low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas 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 also functions as an evaporator. This cycle is repeated to cool the room.

[0028] Heating operation of the air conditioner 1 is performed in a cycle reverse to that of cooling operation. The high-temperature, high-pressure gas refrigerant is adiabatically compressed and discharged by the compressor 2 and sent to the indoor heat exchanger 6 by switching the four-way valve 3. The high-temperature, high-pressure gas refrigerant is cooled by heat exchange with the indoor air in the indoor heat exchanger 6, which functions as a condenser, and becomes liquid refrigerant. The liquid refrigerant is decompressed by the expansion valve 5 and becomes low-temperature, low-pressure liquid refrigerant.

[0029] The low-temperature, low-pressure liquid refrigerant is sent to the outdoor heat exchanger 4. The low-temperature, low-pressure liquid refrigerant evaporates through heat exchange with the outside air in the outdoor heat exchanger 4, which functions as an evaporator, and becomes a low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas 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. Indoor air is given heat through heat exchange with the refrigerant in the indoor heat exchanger 6, which functions as a condenser. This cycle is repeated to heat the room.

[0030] In the air conditioner 1 according to this embodiment, the refrigerant circuit 10 may contain a single refrigerant consisting of a single refrigerant component, or 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 hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), CO2, hydrocarbons, ethers, fluoroethers, fluoroalkenes, etc. may be used. Additives such as stabilizers that suppress decomposition of the refrigerant components and polymerization inhibitors that suppress polymerization of the refrigerant components may be added to the refrigerant.

[0031] In the air conditioner 1 according to this embodiment, a predetermined refrigeration oil is injected into the compressor 2. The refrigeration oil is drawn from an oil reservoir during operation of the compressor 2 and supplied to sliding parts such as the compression mechanism and bearings. The refrigeration oil lubricates, cools, and seals the sliding parts. A portion of the refrigeration oil is discharged from the compressor 2 together with the refrigerant and circulates through the refrigerant circuit 10. Examples of refrigeration oil that can be used include polyol ester oil, polyvinyl ether oil, and polyalkylene glycol oil. The refrigeration oil may contain additives such as an acid scavenger, an antioxidant, an extreme pressure agent, a stabilizer, an antifoaming agent, and a metal deactivator.

[0032] Fig. 3 is a diagram illustrating the internal configuration of the outdoor unit of an air conditioner. Fig. 3 shows an example of the internal structure of the housing of the outdoor unit 100 and the main equipment installed inside. As shown in Fig. 3, the outdoor unit 100 has built-in components such as a compressor 2, a four-way valve 3, an outdoor heat exchanger 4, an expansion valve 5, an accumulator 7, and an outdoor blower fan 8 (not shown).

[0033] The outdoor unit 100 has a housing roughly shaped like a rectangular parallelepiped. The bottom surface of the housing is formed by a bottom base 101. The top surface of the housing is formed by a top plate (not shown). The front surface of the housing is formed by a front plate (not shown). The side and rear surfaces of the housing are formed by side plates, rear plates, etc. (not shown). The housing is formed from a steel plate or the like that is painted to prevent corrosion.

[0034] The interior of the housing of the outdoor unit 100 is divided by a partition plate 105 into a heat exchanger chamber 110 on one side and a machine chamber 120 on the other side. An electrical equipment box (not shown) is provided at the top of the interior of the housing, above the partition plate 105. The heat exchanger chamber 110 is equipped with an outdoor heat exchanger 4, an outdoor blower fan 8, etc. The machine chamber 120 is equipped with a compressor 2, a four-way valve 3, an expansion valve 5, an accumulator 7, etc. The electrical equipment box houses a control board and electrical components.

[0035] The heat exchanger chamber 110 is a section where heat exchange by the outdoor heat exchanger 4 takes place. An air outlet covered with a lattice is provided on the front panel on the front side of the heat exchanger chamber 110. An air inlet is provided on the side and rear panels on the side and rear sides of the heat exchanger chamber 110. When the outdoor blower fan 8 is driven to rotate by the fan motor, it draws outside air into the housing through the air inlet. The air drawn into the housing exchanges heat with the refrigerant by the outdoor heat exchanger 4. The heat-exchanged air is blown out of the housing through the air outlet.

[0036] The outdoor heat exchanger 4 is supported on the bottom base 101. The outdoor heat exchanger 4 is, for example, a cross-fin tube, and includes heat transfer tubes through which the refrigerant flows and a plurality of fins joined to the heat transfer tubes. The heat transfer tubes and fins can be made of, for example, an aluminum alloy. Using aluminum for the heat transfer tubes and fins can reduce material costs and the weight of the heat exchanger. The heat transfer tubes of the outdoor heat exchanger 4 are connected to the refrigerant tubes that make up the refrigerant circuit 10 by brazing or eutectic bonding.

[0037] The machine room 120 is a compartment that houses equipment related to the operation of the outdoor unit 100. Equipment such as the compressor 2, four-way valve 3, expansion valve 5, and accumulator 7, as well as refrigerant pipes that connect these devices, are installed in the machine room 120. A liquid-side service valve 18 to which a liquid pipe is connected and a gas-side service valve 19 to which a gas pipe is connected are attached to the side of the outdoor unit 100 housing on the machine room 120 side.

[0038] One end of a heat transfer tube of the sub-cooler 4b of the outdoor heat exchanger 4 is connected to the internal port of the liquid side service valve 18 via a refrigerant pipe or the like. One end of a heat transfer tube of the indoor heat exchanger 6 is connected to the external port of the liquid side service valve 18 via a refrigerant pipe or the like. One port of the four-way valve 3 is connected to the internal port of the gas side service valve 19 via a refrigerant pipe or the like. The other end of the heat transfer tube of the indoor heat exchanger 6 is connected to the external port of the gas side service valve 19 via a refrigerant pipe or the like.

[0039] The inlet side of the accumulator 7 is connected to another port of the four-way valve 3 via a refrigerant pipe or the like. The suction side of the compressor 2 is connected to the outlet side of the accumulator 7 via a refrigerant pipe or the like. One port of the four-way valve 3 is connected to the discharge side of the compressor 2 via a refrigerant pipe or the like. One end of a heat transfer tube in the main body 4a of the outdoor heat exchanger 4 is connected to the other port of the four-way valve 3 via a refrigerant pipe or the like. One port of the expansion valve 5 is connected to the other end of the heat transfer tube in the main body 4a of the outdoor heat exchanger 4 via a refrigerant pipe or the like. The other end of the heat transfer tube of the sub-cooler 4b of the outdoor heat exchanger 4 is connected to the other port of the expansion valve 5 via a refrigerant pipe or the like.

[0040] Next, the structure of the connection part where dissimilar metals are connected to each other in the refrigerant circuit will be described. In the following description, the refrigerant inlets and outlets of the devices constituting the refrigerant circuit, and the upstream and downstream of the refrigerant flow in the refrigerant circuit will be shown based on the refrigerant flow direction during cooling operation.

[0041] Fig. 4 is a diagram illustrating the structure of a connection in a conventional air conditioner. Fig. 4 shows the structure around an expansion valve 5 connected to a section between the main body 4a of the outdoor heat exchanger 4 and the subcooler 4b on the refrigerant circuit 10. The subcooler 4b is formed below the main body 4a of the outdoor heat exchanger 4. The expansion valve 5 is connected between the heat transfer tubes of the main body 4a of the outdoor heat exchanger 4 and the heat transfer tubes of the subcooler 4b of the outdoor heat exchanger 4 via refrigerant pipes, etc.

[0042] In Fig. 4, the downstream end of a metal refrigerant pipe 12A is connected to the inlet of the expansion valve 5 via a strainer 16A. The metal refrigerant pipe 12A is generally made of copper. The upstream end of the metal refrigerant pipe 12A is connected to the downstream end of an aluminum refrigerant pipe 11A via a connection part 13A. The upstream end of the aluminum refrigerant pipe 11A is connected to the downstream end of a heat transfer pipe of the main body part 4a of the outdoor heat exchanger 4.

[0043] The outlet of the expansion valve 5 is connected to the upstream end of a metal refrigerant pipe 12B via a strainer 16B. The metal refrigerant pipe 12B is generally made of copper. The downstream end of the metal refrigerant pipe 12B is connected to the upstream end of an aluminum refrigerant pipe 11B via a connection part 13B. The downstream end of the aluminum refrigerant pipe 11B is connected to the upstream end of a heat transfer pipe of the sub-cooler 4b of the outdoor heat exchanger 4.

[0044] When the outdoor heat exchanger 4 is converted to aluminum, some of the refrigerant pipes connecting the heat transfer pipes of the main body 4a of the outdoor heat exchanger 4 and the expansion valve 5, and some of the refrigerant pipes connecting the heat transfer pipes of the sub-cooler 4b of the outdoor heat exchanger 4 and the expansion valve 5 may also be converted to aluminum. On the other hand, the copper refrigerant pipes that have been used traditionally may be useful in terms of product assembly and part replaceability, and so there is a possibility that aluminum refrigerant pipes and copper refrigerant pipes will coexist.

[0045] Generally, the connection between an aluminum refrigerant pipe made of aluminum or a metal containing aluminum and a metal refrigerant pipe made of a metal with a lower ionization tendency than aluminum is a joint between dissimilar metals, and therefore is a location prone to galvanic corrosion.

[0046] Water droplets may adhere to the outer surface of refrigerant pipes due to condensation or other reasons. When water droplets adhere to the connection, a local battery is formed between the aluminum and a metal such as copper, which has a lower ionization tendency than aluminum. Furthermore, when water droplets adhere to the outer surface of a metal refrigerant pipe made of copper or other materials, metal ions such as copper ions are eluted into the droplets. Water droplets containing dissolved metal ions may flow down the outer surface of the metal refrigerant pipe and adhere to the aluminum refrigerant pipe.

[0047] These phenomena can lead to galvanic corrosion of connections and aluminum refrigerant pipes. As galvanic corrosion progresses, gaps may form in the connections, or pitting may occur in the connections or aluminum refrigerant pipes, potentially resulting in refrigerant leakage. Galvanic corrosion is particularly likely to occur in connections between aluminum refrigerant pipes and metal refrigerant pipes with low ionization tendency, particularly when the aluminum refrigerant pipes are located vertically below the metal refrigerant pipes. This is because water droplets adhering to the outer surface of the refrigerant pipes flow down along the outer surface due to gravity.

[0048] In conventional air conditioners, as described in Patent Document 1, measures are taken to prevent galvanic corrosion at connections by restricting the shape and arrangement of refrigerant pipes.

[0049] As shown in Fig. 4, in a conventional air conditioner, aluminum refrigerant pipes 11A, 11B are bent into a U-shape so that they are convex upward. Copper metal refrigerant pipes 12A, 12B are bent into a U-shape so that they are convex downward. The ends of aluminum refrigerant pipes 11A, 11B and the ends of metal refrigerant pipes 12A, 12B are connected so that the ends of aluminum refrigerant pipes 11A, 11B are positioned vertically higher than the ends of metal refrigerant pipes 12A, 12B.

[0050] Such a shape and arrangement of the refrigerant pipes prevents water droplets due to condensation or the like from flowing down from the metal refrigerant pipes 12A, 12B into the aluminum refrigerant pipes 11A, 11B.

[0051] However, with this shape and layout, when extending the aluminum refrigerant pipe downward from the connection with the metal refrigerant pipe, the number of U-shaped return bends increases. The return bends increase the overall width of the refrigerant pipe, making it difficult to secure space for arranging the refrigerant pipe. Furthermore, the increased number of return bends increases the manufacturing cost of the refrigerant circuit and the size of the refrigerant circuit.

[0052] Therefore, in the air conditioner 1 according to this embodiment, at least some of the connections at which aluminum refrigerant pipes are connected to metal refrigerant pipes with low ionization tendency are configured so that the end of the aluminum refrigerant pipe is positioned vertically lower than the end of the metal refrigerant pipe. In other words, at least some of the connections provided on the refrigerant circuit 10 are formed by connecting metal refrigerant pipes and aluminum refrigerant pipes in this order from top to bottom.

[0053] Furthermore, in the air conditioner 1 according to this embodiment, the outer surface of a connection between an aluminum refrigerant pipe and a metal refrigerant pipe with a low ionization tendency is covered with a cover, and the connection is targeted at a connection where the end of the aluminum refrigerant pipe is positioned vertically lower than the end of the metal refrigerant pipe. Also, a sacrificial anticorrosion layer is formed on the outer surface of the aluminum refrigerant pipe that forms such a connection.

[0054] This structure avoids restrictions on the shape and placement of refrigerant pipes, while suppressing galvanic corrosion of the aluminum refrigerant pipes and the joints where aluminum refrigerant pipes are connected to metal refrigerant pipes with low ionization tendency over the long term. By installing the joints vertically, freedom and space for installing the refrigerant pipes are ensured, while the cover and sacrificial anticorrosion layer suppress galvanic corrosion caused by water droplets flowing down.

[0055] In general, the useful life of an air conditioner is expected to be approximately 6 to 15 years with preventive maintenance. Considering the safety of an actual product, it is desirable for devices such as heat exchangers, which are not subject to replacement, to have a lifespan of 20 years or more. Based on this premise, the inventor conducted an accelerated SWAAT test based on the SWAAT test in accordance with ASTM on a connection where the end of an aluminum refrigerant pipe was connected so that it was positioned vertically lower than the end of a copper refrigerant pipe.

[0056] For the accelerated SWAAT test, test materials were used that had connections between aluminum refrigerant pipes with a sacrificial corrosion protection layer formed on the outer surface and copper refrigerant pipes. The accelerated SWAAT test was conducted under conditions where water containing dissolved copper ions within a specified concentration range was flowing down. The results confirmed that by using aluminum refrigerant pipes with a sacrificial corrosion protection layer, no through holes were formed in the connections or aluminum refrigerant pipes, even after repeated test cycles equivalent to 20 years, and that the test materials could be used for long periods of time.

[0057] The reason for these test results is thought to be that the base aluminum material did not corrode until the sacrificial corrosion protection layer was lost, and that it took time for the corrosion to progress. Furthermore, the typical copper ion concentration expected to come into contact with aluminum refrigerant pipes is thought to be such that the corrosion rate required to form through-holes does not reach the level required for a 20-year test cycle. Compared to the combined cyclic corrosion test (CCT), which is known to be closer to real-world conditions, the SWAAT test is a test that more easily washes away the passive oxide film. Therefore, based on these test results, it can be said that sufficient corrosion protection is ensured in real-world conditions.

[0058] The air conditioner 1 according to this embodiment includes, on a refrigerant circuit 10, aluminum refrigerant pipes made of aluminum or a metal containing aluminum, metal refrigerant pipes made primarily of a metal with a lower ionization tendency than aluminum, and connectors connecting the aluminum refrigerant pipes to the metal refrigerant pipes. Such connectors may be provided in one location or in multiple locations on the refrigerant circuit 10. Covers and sacrificial protection layers may be provided on all or some of the connectors and aluminum refrigerant pipes on the refrigerant circuit 10.

[0059] Examples of metals containing aluminum include aluminum-manganese alloys, aluminum-silicon alloys, and aluminum-silicon-magnesium alloys. Examples of metals with a lower ionization tendency than aluminum include iron, chromium, nickel, manganese, copper, and alloys containing these. Examples of metal refrigerant pipes include copper refrigerant pipes made of copper or metals containing copper, and stainless steel refrigerant pipes made of stainless steel.

[0060] The use of aluminum refrigerant pipes reduces the material cost of the refrigerant pipes compared to copper refrigerant pipes. Furthermore, products such as outdoor units can be made lighter. Compared to aluminum refrigerant pipes, copper refrigerant pipes are easier to join by brazing or other methods, making it easier to join the refrigerant pipes to equipment and to replace the refrigerant pipes or equipment. The use of stainless steel refrigerant pipes reduces the material cost of the refrigerant pipes compared to copper refrigerant pipes. Furthermore, excellent corrosion resistance can be achieved.

[0061] Figure 5 is a diagram illustrating the structure of a connection part in an air conditioner according to an embodiment of the present invention. The top of Figure 5 indicates the upward direction in the vertical direction. The bottom of Figure 5 indicates the downward direction in the vertical direction. As shown in Figure 5, in an air conditioner 1 according to this embodiment, a connection part 13 is formed by joining together an aluminum refrigerant pipe 11 made of aluminum or a metal containing aluminum and a metal refrigerant pipe 12 made of a metal with a lower ionization tendency than aluminum.

[0062] In Figure 5, the end side of an aluminum refrigerant pipe 11 is fitted onto and joined to the end side of a metal refrigerant pipe 12. The inner surface of the end side of the aluminum refrigerant pipe 11 and the outer surface of the end side of the metal refrigerant pipe 12 are integrated via a joining metal 14. A connecting portion 13 is formed as a region where dissimilar metals overlap in the radial direction of the refrigerant pipe via the joining metal 14. A sacrificial corrosion protection layer 15 is formed on the outer surface of the aluminum refrigerant pipe 11. The outer surface of the connecting portion 13 is covered with a cover 20.

[0063] At the connection portion 13, the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 are connected so that the end of the aluminum refrigerant pipe 11 is positioned vertically lower than the end of the metal refrigerant pipe 12. The aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 may be connected vertically, essentially parallel to the vertical direction, or may be connected obliquely, tilted from the vertical direction. However, from the viewpoint of facilitating the connection of the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 and covering them with the cover 20, a vertical connection is preferable.

[0064] The aluminum refrigerant pipe 11 forming the connection portion 13 and the metal refrigerant pipe 12 forming the connection portion 13 may have a section near the end on the connection portion 13 side oriented vertically, substantially parallel to the vertical direction, or oriented diagonally, tilted from the vertical direction. The section near the end on the opposite side to the end on the connection portion 13 side may have a section near the end on the vertical side oriented vertically, or oriented diagonally, tilted from the vertical direction, or oriented horizontally, substantially parallel to the horizontal direction. However, from the viewpoint of securing space for installing the refrigerant pipes, a vertical orientation is preferable.

[0065] The connection portion 13 can be formed by joining the end of the aluminum refrigerant pipe 11 and the end of the metal refrigerant pipe 12 by brazing or eutectic bonding. Eutectic bonding is a method of diffusion bonding materials at low temperature and low pressure using the eutectic reaction between aluminum and copper. Brazing or eutectic bonding can be performed using the inner surface of the end of the aluminum refrigerant pipe 11, on which the sacrificial corrosion protection layer 15 is formed, and the outer surface of the end of the metal refrigerant pipe 12 as the joining surfaces. When the expanded aluminum refrigerant pipe 11 is fitted onto the metal refrigerant pipe 12, the joining surfaces can be heated without excessively heating the aluminum refrigerant pipe 11 during joining, thereby preventing the aluminum refrigerant pipe 11 from melting.

[0066] The sacrificial corrosion protection layer 15 provides corrosion protection by lowering the electrode potential of aluminum to a base potential, which is the passive region, and by sacrificial corrosion protection, which involves the sacrificial corrosion of metals that exhibit a higher corrosion potential than aluminum in aqueous solution or seawater, or base metals that have a higher ionization tendency than aluminum. Examples of materials for the sacrificial corrosion protection layer 15 include zinc, zinc alloys, and aluminum alloys to which metals that exhibit a higher corrosion potential than aluminum in aqueous solution or seawater, or base metals that have a higher ionization tendency than aluminum, have been added. Examples of zinc alloys include zinc-aluminum alloys and zinc-nickel alloys.

[0067] The sacrificial protection layer 15 can be formed by a thermal spraying method such as flame spraying, arc spraying, or laser spraying; a cladding method in which materials are pressure-bonded together; or a plating method such as hot-dip galvanizing or displacement plating. When using a thermal spraying method, the formed sacrificial protection layer 15 may be subjected to sealing, heat treatment, polishing, grinding, etc. When using a cladding method, pressure bonding can be achieved by rolling or drawing. The sacrificial protection layer 15 is preferably formed over substantially the entire outer surface of the aluminum refrigerant pipe 11 that constitutes the connection portion 13.

[0068] The thickness of the sacrificial corrosion protection layer 15 is preferably 75 μm or more, and more preferably 100 μm or more. The thickness of the sacrificial corrosion protection layer 15 can be, for example, 200 μm or less, 150 μm or less, or 125 μm or less. If the thickness is 75 μm or more, corrosion protection performance can be ensured for a long period of time that exceeds the standard usage period of equipment that is not subject to replacement, for example, for about 20 years.

[0069] The cover 20 covers the outer surfaces of the connection portion 13 and the aluminum refrigerant pipe 11 so as to cover the joint portion of the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 made by the joining metal 14 and the gap between the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 over a sufficient length in the longitudinal direction of the refrigerant pipe. The cover 20 may cover only the periphery of the connection portion 13, or it may cover the connection portion 13 and the aluminum refrigerant pipe 11. The aluminum refrigerant pipe 11 may be covered from the end on the connection portion 13 side to the middle portion, or from the end on the connection portion 13 side to the end located opposite the end on the connection portion 13 side, etc.

[0070] The upper end of the cover 20 is preferably located above the connection portion 13 between the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12, and more preferably above the processed section on the end side of the metal refrigerant pipe 12. The upper end of the cover 20 may be located near the lower end of the enlarged diameter portion of the metal refrigerant pipe 12 or the equipment connected to the metal refrigerant pipe 12. The metal refrigerant pipe 12 or the equipment connected to the metal refrigerant pipe 12 can be provided with an enlarged diameter portion in which the outer diameter of the upper side is larger than the outer diameter of the lower side. The enlarged diameter portion can be formed by processing the refrigerant pipe or by connecting a joint, refrigerant pipe, etc.

[0071] The lower end of the cover 20 is preferably located below the connection 13 between the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12, and is preferably located below the processed section on the end side of the aluminum refrigerant pipe 11, or on the end side located opposite the end on the connection 13 side of the bend part of the aluminum refrigerant pipe 11. The aluminum refrigerant pipe 11 can be bent into an elbow shape or an inclined elbow shape at the bend part to connect to other refrigerant pipes, equipment, etc.

[0072] The cover 20 is cylindrically shaped so as to cover the entire circumference of the connection portion 13. The cover 20 can be a covering material in the form of a tube, sheet, tape, or the like. The cover 20 is preferably formed from a resin or elastomer that exhibits electrical insulation and elasticity. Electrical insulation can more reliably prevent the formation of local batteries due to moisture or the like. Furthermore, elasticity can ensure adhesion to the outer surface of the connection portion 13, thereby preventing water droplets and outside air from entering the joints and gaps between the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12.

[0073] It is preferable to use a heat-shrinkable tube as the cover 20. A heat-shrinkable tube is a covering member that shrinks in outer and inner diameter when heated. The heat-shrinkable tube can be heated with a heat gun or the like after covering to adhere tightly to the outer surface of the connection part 13 and the outer surface of the aluminum refrigerant pipe 11. This more reliably prevents water droplets and outside air from entering the joints and gaps between the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12.

[0074] Examples of materials for heat-shrinkable tubing include polyvinyl chloride, silicone rubber, polyolefin, polystyrene, polyester, polycarbonate, polyamide, polyimide, polyamideimide, fluororesin, and acrylic resin. Examples of polyolefin include polyethylene and polypropylene. Examples of fluororesin include polytetrafluoroethylene and polyvinylidene fluoride. Examples of acrylic resin include ethylene-methyl acrylate copolymer and ethylene-ethyl acrylate copolymer.

[0075] As shown in Figure 5, at connection 13 where aluminum refrigerant pipe 11 and metal refrigerant pipe 12 are connected so that the end of aluminum refrigerant pipe 11 is positioned vertically lower than the end of metal refrigerant pipe 12, if the connection is not covered by cover 20, when water droplets due to condensation or the like adhere to the outer surface of metal refrigerant pipe 12, the water droplets will flow down from metal refrigerant pipe 12 and enter the joints and gaps between aluminum refrigerant pipe 11 and metal refrigerant pipe 12, or adhere to the outer surface of aluminum refrigerant pipe 11.

[0076] However, when the connection portion 13 and the aluminum refrigerant pipe 11 are covered with the cover 20, it becomes difficult for water droplets and outside air to penetrate into the joints and gaps between the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12. It also becomes difficult for water droplets and outside air to come into contact with the outer surfaces of the connection portion 13 and the aluminum refrigerant pipe 11. Furthermore, when a sacrificial corrosion protection layer 15 is formed on the outer surface of the aluminum refrigerant pipe 11, even if water comes into contact with the aluminum refrigerant pipe, it has the effect of lowering the electrode potential of the aluminum to a passive state and the effect of sacrificial protection, which causes base metals to corrode preferentially. These effects enable galvanic corrosion of the connection portion 13 and the aluminum refrigerant pipe 11 to be suppressed for a long period of time.

[0077] Therefore, by using aluminum refrigerant pipes with a cover covering the connection portion or with a sacrificial corrosion protection layer, when connecting aluminum refrigerant pipes to metal refrigerant pipes, unlike conventional methods, it is possible to place the aluminum refrigerant pipe below the metal refrigerant pipe. Furthermore, because the cover and sacrificial corrosion protection layer suppress galvanic corrosion, there is no need to bend the aluminum refrigerant pipe or the metal refrigerant pipe into a U-shape or other shape to prevent water droplets from flowing down. Aluminum refrigerant pipes and metal refrigerant pipes can be configured in any shape, such as a straight pipe, elbow, or angled elbow. Since it is easier to secure space for refrigerant pipe placement, freedom in refrigerant circuit design is ensured. Furthermore, the overall width of the refrigerant pipe is reduced, improving freedom in refrigerant pipe placement, thereby avoiding an increase in the size of the refrigerant circuit. Furthermore, because there is no need to bend the refrigerant pipe into a U-shape or other shape, the manufacturing cost of the refrigerant circuit is reduced. Therefore, it is possible to suppress galvanic corrosion at the connection points where aluminum refrigerant pipes and metal refrigerant pipes are connected for a period exceeding the standard usage period, while reducing the manufacturing costs of the refrigerant circuit and ensuring freedom in designing the refrigerant circuit.

[0078] The connection 13, at which the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 are connected, is preferably provided in one or more of the following sections in the refrigerant circuit 10: the section between the outdoor heat exchanger 4 and the expansion valve 5, the section between the expansion valve 5 and the liquid-side service valve 18, the section between the four-way valve 3 and the outdoor heat exchanger 4, the section between the indoor exchanger 6 and the liquid-side service valve 18, and the section between the indoor exchanger 6 and the gas-side service valve 19. The connection 13 may be provided in the section between the main body 4a of the outdoor heat exchanger 4 and the expansion valve 5, in the section between the expansion valve 5 and the subcooler 4b of the outdoor heat exchanger 4, or in the section between the subcooler 4b of the outdoor heat exchanger 4 and the liquid-side service valve 18.

[0079] The aluminum refrigerant pipe 11 with the sacrificial corrosion protection layer 15 formed thereon is preferably connected to one or more of the inlet / outlet on the expansion valve 5 side of the outdoor heat exchanger 4, the inlet / outlet on the liquid side service valve 18 side of the outdoor heat exchanger 4, the inlet / outlet on the four-way valve 3 side of the outdoor heat exchanger 4, the inlet / outlet on the liquid side service valve 18 side of the indoor heat exchanger 6, and the inlet / outlet on the gas side service valve 19 side of the indoor heat exchanger 6. When connected to such locations, the outdoor heat exchanger 4, the indoor heat exchanger 6, and the surrounding refrigerant pipes and equipment can be converted to aluminum, reducing material costs and the weight of the equipment.

[0080] For example, the aluminum refrigerant pipe 11 with the sacrificial corrosion protection layer 15 formed thereon can be connected to one or more of the inlet / outlet on the expansion valve 5 side of the main body 4a of the outdoor heat exchanger 4, the inlet / outlet on the expansion valve 5 side of the subcooler 4b of the outdoor heat exchanger 4, the inlet / outlet on the liquid side service valve 18 side of the subcooler 4b of the outdoor heat exchanger 4, the inlet / outlet on the four-way valve 3 side of the main body 4a of the outdoor heat exchanger 4, the inlet / outlet on the liquid side service valve 18 side of the indoor heat exchanger 6, and the inlet / outlet on the gas side service valve 19 side of the indoor heat exchanger 6. The aluminum refrigerant pipes 11 connected to such locations can be extended upward and connected to metal refrigerant pipes 12 extended downward.

[0081] The structure in which the connection parts 13 are covered with the cover 20 and the aluminum refrigerant pipes 11 on which the sacrificial corrosion protection layer 15 is formed suppresses galvanic corrosion of the connection parts 13 and the aluminum refrigerant pipes 11, even if the aluminum refrigerant pipes 11 are arranged lower than the metal refrigerant pipes 12. Therefore, the subcooler 4b can be arranged below the outdoor heat exchanger 4 and the four-way valve 3 can be arranged above the machine room 120, without being subject to significant restrictions on the shape and arrangement of the refrigerant pipes.

[0082] The aluminum refrigerant pipes 11 and metal refrigerant pipes 12 that are connected to each other are preferably arranged in the refrigerant circuit 10 so that the surface area or length along the center line of the aluminum refrigerant pipe 11, i.e., the total length of the pipe formed by the aluminum refrigerant pipe 11, is longer than the surface area or length along the center line of the metal refrigerant pipe 12, i.e., the total length of the pipe formed by the metal refrigerant pipe 12. This is because the greater the ratio of the surface area of ​​the aluminum refrigerant pipe 11 to the metal refrigerant pipe 12, the slower the progression of corrosion.

[0083] When the air conditioner 1 is equipped with an outdoor heat exchanger having aluminum heat transfer tubes made of aluminum or a metal containing aluminum and aluminum fins made of aluminum or a metal containing aluminum, or an indoor heat exchanger having aluminum heat transfer tubes made of aluminum or a metal containing aluminum and aluminum fins made of aluminum or a metal containing aluminum, it is preferable that the aluminum refrigerant tube 11 that constitutes the connection part 13 is connected to one or more of these aluminum heat transfer tubes.

[0084] In such a case, it is preferable that the total surface area of ​​the aluminum refrigerant pipes 11, aluminum heat transfer pipes, and aluminum fins that make up the connection part 13 is at least 10 times the surface area of ​​the metal refrigerant pipes 12 that make up the connection part 13. With this area ratio, the rate of acceleration of aluminum corrosion due to contact with copper or the like, which has a lower ionization tendency than aluminum, can be kept low.

[0085] Regarding the acceleration rate of corrosion due to contact between dissimilar metals, it has been reported that when the area ratio of aluminum to copper is 10 times, the acceleration rate of corrosion due to contact between aluminum and copper in flowing seawater, which has good electrical conductivity, doubles (see Kawamoto Teruaki, "Gastric Corrosion," Corrosion Prevention Technology, Corrosion Prevention Society, 1984, Vol. 33, No. 8, pp. 478-479:<https: / / www.jstage.jst.go.jp / article / jcorr1974 / 33 / 8 / 33_8_478 / _pdf> ).

[0086] Fig. 6 is a diagram illustrating the structure of a refrigerant pipe connected between an outdoor heat exchanger and an expansion valve in an air conditioner according to an embodiment of the present invention. Fig. 6 shows the structure of connecting an aluminum refrigerant pipe connected to the outlet side of the outdoor heat exchanger during cooling operation and a metal refrigerant pipe connected to the inlet side of the expansion valve during cooling operation.

[0087] As shown in Figure 6, in the air conditioner 1 according to this embodiment, a structure in which the connection portion 13 where the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 are connected is covered with a cover 20, or the aluminum refrigerant pipe 11 on which the sacrificial corrosion protection layer 15 is formed can be provided in the section between the outdoor heat exchanger 4 and the expansion valve 5, for example, the section between the main body 4a of the outdoor heat exchanger 4 and the expansion valve 5. The aluminum refrigerant pipe 11 on which the sacrificial corrosion protection layer 15 is formed can be connected to the inlet / outlet of the outdoor heat exchanger 4 on the expansion valve 5 side.

[0088] In Fig. 6, the downstream ends of a plurality of heat transfer tubes 4c protrude from a side of the main body 4a of the outdoor heat exchanger 4. The downstream end of each heat transfer tube 4c is connected to the upstream end of an aluminum refrigerant tube 11n. The downstream ends of the aluminum refrigerant tubes 11n are connected to the inlet side of a distributor 21. The distributor 21 is a device that merges a plurality of flow paths into one flow path or splits one flow path into multiple flow paths depending on the refrigerant flow direction. A plurality of thin aluminum refrigerant tubes 11n, through which split refrigerant can flow, are connected to the distributor 21 so that the multiple refrigerant flow paths can merge.

[0089] The upstream end of an aluminum refrigerant pipe 11a is connected to the outlet side of the distributor 21. The upstream end of a metal refrigerant pipe 12a is connected to the downstream end of the aluminum refrigerant pipe 11a via a connection part 13a. The downstream end of the metal refrigerant pipe 12a is connected to the inlet side of the main body of the expansion valve 5 via a strainer 16a and a metal refrigerant pipe connected to the main body of the expansion valve 5. The upstream end of a metal refrigerant pipe 12b is connected to the outlet side of the main body of the expansion valve 5 via a metal refrigerant pipe connected to the main body of the expansion valve 5 and a strainer 16b. The downstream end of the metal refrigerant pipe 12b is connected to the upstream end of a heat transfer pipe of a sub-cooler 4b of the outdoor heat exchanger 4 via a refrigerant pipe or the like.

[0090] The aluminum refrigerant pipe 11a and the metal refrigerant pipe 12a are not bent into a U-shape and are formed only as straight pipe sections. The aluminum refrigerant pipe 11a and the metal refrigerant pipe 12a are connected so that the end of the aluminum refrigerant pipe 11a is positioned vertically lower than the end of the metal refrigerant pipe 12a. A sacrificial corrosion protection layer 15 is formed on the aluminum refrigerant pipe 11a to cover its outer surface. The connection portion 13a and the aluminum refrigerant pipe 11a are covered with a cover 20.

[0091] In Figure 6, the aluminum refrigerant pipe 11a has only a straight section, but it may also have an elbow section or an inclined elbow section bent at an angle of less than 90 degrees. The aluminum refrigerant pipe 11a is not bent in a U-shape by 180 degrees. The metal refrigerant pipe 12d has only a straight section, but it may also have an elbow section or an inclined elbow section bent at an angle of less than 90 degrees.

[0092] Cover 20 is arranged to cover the periphery of connection portion 13a and aluminum refrigerant pipe 11a, but may also be arranged to cover only the periphery of connection portion 13a. The upper end of cover 20 may be located above connection portion 13a, or near the lower end of strainer 16a. The lower end of cover 20 is preferably located near the middle of aluminum refrigerant pipe 11a below connection portion 13a, near the end of aluminum refrigerant pipe 11a below connection portion 13a, near the upper end of distributor 21 below connection portion 13a, or on the outdoor heat exchanger 4 side of distributor 21.

[0093] This arrangement more reliably prevents water droplets and outside air from entering the joints and gaps between the aluminum refrigerant pipes 11a and the metal refrigerant pipes 12a, and more reliably prevents moisture from coming into contact with the connecting parts 13a and the aluminum refrigerant pipes 11a. The longer the cover 20, the more work required for the covering process, but it can more widely prevent pitting corrosion and other problems in the aluminum refrigerant pipes 11a. The distributor 21 can be made of, for example, aluminum or a metal containing aluminum.

[0094] In the section between the outdoor heat exchanger 4 and the expansion valve 5, the connection part 13a may be provided above or below the midpoint between the lowest and highest points in the vertical direction on the refrigerant circuit connecting the outlet of the distributor 21 and the inlet of the expansion valve 5. If the connection part 13a is located on the upper side, the section of the aluminum refrigerant pipe 11a becomes longer, which is advantageous for reducing material costs and the weight of the equipment. On the other hand, if the connection part 13a is located on the lower side, the section of the aluminum refrigerant pipe 11a becomes shorter, which reduces the overall length of the cover 20 and the man-hours required for covering.

[0095] When the connection part 13 covered with the cover 20 is provided in the section between the outdoor heat exchanger 4 and the expansion valve 5, even if water droplets due to condensation or the like adhere to the outer surface of the metal refrigerant tube 12 whose temperature has dropped in a situation where the refrigerant is decompressed by the expansion valve 5 and the refrigerant temperature drops, the cover 20 can prevent moisture from entering the joint between the aluminum refrigerant tube 11 and the metal refrigerant tube 12 or the gap between the aluminum refrigerant tube 11 and the metal refrigerant tube 12, or from coming into contact with the outer surface of the connection part 13 or the outer surface of the aluminum refrigerant tube 11. Furthermore, when the aluminum refrigerant tube 11 with the sacrificial corrosion protection layer 15 formed thereon is provided in the section between the outdoor heat exchanger 4 and the expansion valve 5, the sacrificial corrosion protection layer 15 can protect the connection part 13 and the aluminum refrigerant tube 11 from corrosion even if moisture adheres to the inside of the cover 20 or the outer surface of the aluminum refrigerant tube 11. Therefore, in the air conditioner 1 in which the outdoor heat exchanger 4 is made of aluminum, galvanic corrosion of the connection parts 13 and the aluminum refrigerant pipes 11 can be suppressed for a long period of time.

[0096] Fig. 7 is a diagram illustrating the structure of a refrigerant pipe connected between an expansion valve and an outdoor heat exchanger in an air conditioner according to an embodiment of the present invention. Fig. 7 shows the structure of connecting a metal refrigerant pipe connected to the outlet side of the expansion valve during cooling operation and an aluminum refrigerant pipe connected to the inlet side of the sub-cooler of the outdoor heat exchanger during cooling operation.

[0097] 7, in the air conditioner 1 according to this embodiment, the connection portion 13 where the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 are connected can be covered with a cover 20, and the aluminum refrigerant pipe 11 on which the sacrificial corrosion protection layer 15 is formed can also be provided in the section between the expansion valve 5 and the outdoor heat exchanger 4, for example, the section between the expansion valve 5 and the subcooler 4b of the outdoor heat exchanger 4. The aluminum refrigerant pipe 11 on which the sacrificial corrosion protection layer 15 is formed can be connected to the inlet / outlet on the expansion valve 5 side of the subcooler 4b of the outdoor heat exchanger 4.

[0098] In Fig. 7, the upstream end of a metal refrigerant pipe 12b is connected to the outlet side of the expansion valve 5 via a strainer 16b. The upstream end of an aluminum refrigerant pipe 11b is connected to the downstream end of the metal refrigerant pipe 12b via a connection part 13b. The upstream end of a heat transfer pipe 4c of a subcooler 4b of the outdoor heat exchanger 4 is connected to the downstream end of the aluminum refrigerant pipe 11b. In Fig. 7, the dashed line area indicated by the symbol 4b indicates the area of ​​the subcooler 4b formed by the heat transfer pipe 4c passing through the lower part of the outdoor heat exchanger 4. A liquid-side service valve 18 is connected to the downstream end of the heat transfer pipe 4c of the subcooler 4b via a refrigerant pipe.

[0099] The aluminum refrigerant pipe 11b and the metal refrigerant pipe 12b are not bent into a U-shape, but are formed only with straight pipe sections, elbow-shaped sections, and inclined elbow-shaped sections. The aluminum refrigerant pipe 11b and the metal refrigerant pipe 12b are connected so that the end of the aluminum refrigerant pipe 11b is positioned vertically lower than the end of the metal refrigerant pipe 12b. A sacrificial corrosion protection layer 15 is formed on the aluminum refrigerant pipe 11b to cover its outer surface. The connection portion 13b and the aluminum refrigerant pipe 11b are covered with a cover 20.

[0100] In Figure 7, the aluminum refrigerant pipe 11b has a straight pipe section, an elbow section, and an inclined elbow section, but it may have only straight pipe sections. The aluminum refrigerant pipe 11b is not bent 180 degrees into a U-shape. The metal refrigerant pipe 12b has a straight pipe section and an inclined elbow section, but it may also have an elbow section, a return bend section bent into a U-shape, or the like.

[0101] Cover 20 is arranged to cover the periphery of connection portion 13b and aluminum refrigerant pipe 11b, but it may also be arranged to cover only the periphery of connection portion 13b. The upper end of cover 20 may be located above connection portion 13b, or near the lower end of strainer 16b. The lower end of cover 20 is preferably located near the middle of aluminum refrigerant pipe 11b below connection portion 13b, near the end of aluminum refrigerant pipe 11b below connection portion 13b, or on the outdoor heat exchanger 4 side of bend portion 17b of aluminum refrigerant pipe 11b below connection portion 13b.

[0102] This arrangement more reliably prevents water droplets and outside air from entering the joints and gaps between the aluminum refrigerant pipes 11b and the metal refrigerant pipes 12b, and more reliably prevents moisture from coming into contact with the connecting parts 13b and the aluminum refrigerant pipes 11b. The longer the cover 20, the more work required for the covering process, but it can more widely prevent pitting corrosion and other problems in the aluminum refrigerant pipes 11b. The bend portion 17b is provided as a bent section that extends the aluminum refrigerant pipe 11b from the vertical direction to the horizontal direction toward the outdoor heat exchanger 4. The bend portion 17b may be provided in multiple stages. It is preferable that the lower end of the cover 20 be closer to the outdoor heat exchanger 4 than the first bend portion 17b from the connecting part 13b side.

[0103] In the section between the expansion valve 5 and the outdoor heat exchanger 4, the connection part 13b may be located above or below the midpoint between the lowest and highest points in the vertical direction on the refrigerant circuit connecting the outlet of the expansion valve 5 and the inlet of the sub-cooler 4b. If the connection part 13b is located on the upper side, the section of the aluminum refrigerant pipe 11b will be longer, which is advantageous for reducing material costs and the weight of the equipment. On the other hand, if the connection part 13b is located on the lower side, the section of the aluminum refrigerant pipe 11b will be shorter, which can reduce the overall length of the cover 20 and the man-hours required for the covering work.

[0104] When the connection part 13 covered with the cover 20 is provided in the section between the expansion valve 5 and the outdoor heat exchanger 4, even if water droplets due to condensation or the like adhere to the outer surface of the metal refrigerant tube 12 whose temperature has dropped in a situation where the refrigerant is decompressed by the expansion valve 5 and the refrigerant temperature drops, the cover 20 can prevent moisture from entering the joint between the aluminum refrigerant tube 11 and the metal refrigerant tube 12 or the gap between the aluminum refrigerant tube 11 and the metal refrigerant tube 12, or from coming into contact with the outer surface of the connection part 13 or the outer surface of the aluminum refrigerant tube 11. Furthermore, when the aluminum refrigerant tube 11 with the sacrificial corrosion protection layer 15 formed thereon is provided in the section between the expansion valve 5 and the outdoor heat exchanger 4, the sacrificial corrosion protection layer 15 can protect the connection part 13 and the aluminum refrigerant tube 11 from corrosion even if moisture adheres to the inside of the cover 20 or the outer surface of the aluminum refrigerant tube 11. Therefore, in the air conditioner 1 in which the outdoor heat exchanger 4 is made of aluminum, galvanic corrosion of the connection parts 13 and the aluminum refrigerant pipes 11 can be suppressed for a long period of time.

[0105] Fig. 8 is a diagram illustrating the structure of a refrigerant pipe connected between an outdoor heat exchanger and a liquid-side service valve in an air conditioner according to an embodiment of the present invention. Fig. 8 shows the structure of connecting an aluminum refrigerant pipe connected to the outlet side of the sub-cooler of the outdoor heat exchanger during cooling operation with a metal refrigerant pipe connected to the inlet side of the liquid-side service valve during cooling operation.

[0106] 8, in the air conditioner 1 according to this embodiment, the connection portion 13 where the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 are connected may be covered with a cover 20, or the aluminum refrigerant pipe 11 on which the sacrificial corrosion protection layer 15 is formed may be provided in the section between the outdoor heat exchanger 4 and the liquid-side service valve 18, for example, in the section between the subcooler 4b of the outdoor heat exchanger 4 and the liquid-side service valve 18. The aluminum refrigerant pipe 11 on which the sacrificial corrosion protection layer 15 is formed may be connected to the inlet / outlet of the subcooler 4b of the outdoor heat exchanger 4 on the liquid-side service valve 18 side.

[0107] In Figure 8, the dashed line area designated by reference symbol 4b indicates the area of ​​the subcooler 4b formed by the heat transfer tubes 4c that pass through the lower part of the outdoor heat exchanger 4. The upstream end of an aluminum refrigerant tube 11c is connected to the downstream end of the heat transfer tube 4c of the subcooler 4b of the outdoor heat exchanger 4. The upstream end of a metal refrigerant tube 12c is connected to the downstream end of the aluminum refrigerant tube 11c via a connection part 13c. The internal port of the liquid-side service valve 18 is connected to the downstream end of the metal refrigerant tube 12c.

[0108] The aluminum refrigerant pipe 11c and the metal refrigerant pipe 12c are not bent into a U-shape, but are formed only with straight pipe sections, elbow-shaped sections, and inclined elbow-shaped sections. The aluminum refrigerant pipe 11c and the metal refrigerant pipe 12c are connected so that the end of the aluminum refrigerant pipe 11c is positioned vertically lower than the end of the metal refrigerant pipe 12c. A sacrificial corrosion protection layer 15 is formed on the aluminum refrigerant pipe 11c to cover its outer surface. The connection portion 13c and the aluminum refrigerant pipe 11c are covered with a cover 20.

[0109] In Figure 8, the aluminum refrigerant pipe 11c has a straight pipe section, an elbow section, and an inclined elbow section, but it may also have only straight pipe sections or elbow sections. The aluminum refrigerant pipe 11c is not bent 180 degrees into a U-shape. The metal refrigerant pipe 12c has a straight pipe section, an elbow section, and an inclined elbow section, but it may also have a return bend section bent into a U-shape.

[0110] Cover 20 is arranged to cover the periphery of connection portion 13c and aluminum refrigerant pipe 11c, but may also be arranged to cover only the periphery of connection portion 13c. The upper end of cover 20 is preferably located above connection portion 13c. The lower end of cover 20 is preferably located near the middle of aluminum refrigerant pipe 11c below connection portion 13c, near the end of aluminum refrigerant pipe 11c below connection portion 13c, or closer to outdoor heat exchanger 4 than bend portion 17c below connection portion 13c.

[0111] This arrangement more reliably prevents water droplets and outside air from entering the joints and gaps between the aluminum refrigerant pipes 11c and the metal refrigerant pipes 12c, and prevents moisture from coming into contact with the connecting parts 13c and the aluminum refrigerant pipes 11c. The longer the cover 20, the more work required for the covering process, but it can more widely prevent pitting corrosion and other problems in the aluminum refrigerant pipes 11c. The bend portion 17c is provided as a bent section that extends the aluminum refrigerant pipe 11c from the vertical direction to the horizontal direction toward the outdoor heat exchanger 4. The bend portion 17c may be provided in multiple stages. It is preferable that the lower end of the cover 20 be closer to the outdoor heat exchanger 4 than the first bend portion 17c from the connecting part 13c side.

[0112] In the section between the outdoor heat exchanger 4 and the liquid-side service valve 18, the connection portion 13c may be located above or below the midpoint between the lowest and highest points in the vertical direction on the refrigerant circuit connecting the outlet of the subcooler 4b and the inlet of the liquid-side service valve 18. If the connection portion 13c is located above, the section of the aluminum refrigerant pipe 11c becomes longer, which is advantageous for reducing material costs and the weight of the equipment. On the other hand, if the connection portion 13c is located below, the section of the aluminum refrigerant pipe 11c becomes shorter, which reduces the overall length of the cover 20 and the man-hours required for the covering work.

[0113] When the connection 13 covered with the cover 20 is provided in the section between the outdoor heat exchanger 4 and the liquid-side service valve 18, even if water droplets due to condensation or the like form on the outer surface of the metal refrigerant tube 12 whose temperature has dropped in situations such as when the refrigerant is decompressed by the expansion valve 5 and its temperature drops, or when the refrigerant is cooled by the subcooler 4b, the cover 20 can prevent moisture from entering the joints between the aluminum refrigerant tubes 11 and 12 or the gaps between the aluminum refrigerant tubes 11 and 12, or from coming into contact with the outer surface of the connection 13 or the outer surface of the aluminum refrigerant tube 11. Furthermore, when the aluminum refrigerant tube 11 with the sacrificial corrosion protection layer 15 is provided in the section between the outdoor heat exchanger 4 and the liquid-side service valve 18, the sacrificial corrosion protection layer 15 can protect the connection 13 and the aluminum refrigerant tube 11 from corrosion even if moisture adheres to the inside of the cover 20 or the outer surface of the aluminum refrigerant tube 11. Therefore, in the air conditioner 1 in which the outdoor heat exchanger 4 is made of aluminum, galvanic corrosion of the connection parts 13 and the aluminum refrigerant pipes 11 can be suppressed for a long period of time.

[0114] Fig. 9 is a diagram illustrating the structure of a refrigerant pipe connected between a four-way valve and an outdoor heat exchanger in an air conditioner according to an embodiment of the present invention. Fig. 9 shows the structure of connecting a metal refrigerant pipe connected to the outlet of the four-way valve on the outdoor heat exchanger side with an aluminum refrigerant pipe connected to the inlet side of the outdoor heat exchanger during cooling operation.

[0115] As shown in Figure 9, in the air conditioner 1 according to this embodiment, the connection portion 13 where the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 are connected can be covered with a cover 20, and the aluminum refrigerant pipe 11 on which the sacrificial corrosion protection layer 15 is formed can also be provided in the section between the four-way valve 3 and the outdoor heat exchanger 4. The aluminum refrigerant pipe 11 on which the sacrificial corrosion protection layer 15 is formed can be connected to the inlet / outlet of the outdoor heat exchanger 4 on the four-way valve 3 side.

[0116] In Figure 9, the four-way valve 3 has a horizontally installed cylindrical body with a valve element and other components built in. Three ports are formed in the lower part of the body. One port is formed in the upper part of the body. The four-way valve body and each port are made of, for example, copper or a copper alloy. The upper port is connected to the upstream end of a metal refrigerant pipe 12d. The metal refrigerant pipe 12d is bent in a U-shape so that it is convex upward.

[0117] The downstream end of the metal refrigerant pipe 12d is connected via a connector 13d to the upstream end of an aluminum refrigerant pipe 11d, which is a gas header pipe. A plurality of thin aluminum refrigerant pipes 11m, through which the diverted refrigerant can flow, are connected to the downstream side of the aluminum refrigerant pipe 11d so that the refrigerant flow path branches into multiple paths. The downstream end of each aluminum refrigerant pipe 11m is connected to the upstream end of a heat transfer pipe 4c of the main body 4a of the outdoor heat exchanger 4. The upstream ends of the heat transfer pipes 4c protrude from the side of the main body 4a of the outdoor heat exchanger 4.

[0118] As shown in Figure 9, aluminum refrigerant pipe 11d, which is a gas header pipe, is not bent into a U-shape and is formed only by straight pipe sections and elbow-shaped sections. Aluminum refrigerant pipe 11d and metal refrigerant pipe 12d are connected so that the end of aluminum refrigerant pipe 11d is positioned vertically lower than the end of metal refrigerant pipe 12d. A sacrificial corrosion protection layer 15 is formed on aluminum refrigerant pipe 11d to cover its outer surface. Connection portion 13d and aluminum refrigerant pipe 11d are covered with cover 20.

[0119] In Figure 9, the aluminum refrigerant pipe 11d, which is a gas header pipe, has a straight section and an elbow section, but it may also have only straight sections or sections with an inclined elbow bend at an angle of less than 90 degrees. The aluminum refrigerant pipe 11d is not bent in a U-shape by 180 degrees. The metal refrigerant pipe 12d may have a straight section, an elbow section, an inclined elbow section, a return bend section bent in a U-shape, or the like.

[0120] Cover 20 is arranged to cover the periphery of connection portion 13d and aluminum refrigerant pipe 11d, which is the gas header pipe, but it may also be arranged to cover only the periphery of connection portion 13d. The upper end of cover 20 is preferably located above connection portion 13d. The lower end of cover 20 is preferably located closer to outdoor heat exchanger 4 than bend portion 17d below connection portion 13d, or closer to four-way valve 3 than the branch point to which thin-walled aluminum refrigerant pipe 11m of aluminum refrigerant pipe 11d below connection portion 13d is connected.

[0121] This arrangement more reliably prevents water droplets and outside air from entering the joints and gaps between the aluminum refrigerant pipe 11d and the metal refrigerant pipe 12d, and more reliably prevents moisture from coming into contact with the connecting portion 13d and the aluminum refrigerant pipe 11d. The longer the cover 20, the more work required for the covering process, but it also more effectively prevents pitting corrosion and other problems in the aluminum refrigerant pipe 11d over a wider area. The bend 17d is provided as a bent section that extends the aluminum refrigerant pipe 11d from the vertical direction to the horizontal direction toward the outdoor heat exchanger 4. The bend 17d may be provided in multiple stages. It is preferable that the lower end of the cover 20 be closer to the outdoor heat exchanger 4 than the first bend 17d from the connecting portion 13d, and closer to the four-way valve 3 than the first branch point from the connecting portion 13d.

[0122] In the section between the four-way valve 3 and the outdoor heat exchanger 4, the connection portion 13d may be located above or below the midpoint between the lowest and highest points in the vertical direction on the refrigerant circuit connecting the outlet of the four-way valve 3 and the heat transfer tube 4c of the main body 4a of the outdoor heat exchanger 4. If the connection portion 13d is located above, the section of the aluminum refrigerant tube 11d will be longer, which is advantageous for reducing material costs and the weight of the equipment. On the other hand, if the connection portion 13d is located below, the section of the aluminum refrigerant tube 11d will be shorter, which can reduce the overall length of the cover 20 and the man-hours required for covering.

[0123] When the connection part 13 covered with the cover 20 is provided in the section between the four-way valve 3 and the outdoor heat exchanger 4, even if water droplets due to condensation or the like adhere to the outer surface of the metal refrigerant pipe 12 during heating operation when the outdoor heat exchanger 4 functions as an evaporator or in high-humidity conditions, the cover 20 can prevent moisture from entering the joint between the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 or the gap between the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12, or from coming into contact with the outer surface of the connection part 13 or the outer surface of the aluminum refrigerant pipe 11. Furthermore, when the aluminum refrigerant pipe 11 with the sacrificial corrosion protection layer 15 formed thereon is provided in the section between the four-way valve 3 and the outdoor heat exchanger 4, the sacrificial corrosion protection layer 15 can protect the connection part 13 and the aluminum refrigerant pipe 11 from corrosion even if moisture adheres to the inside of the cover 20 or the outer surface of the aluminum refrigerant pipe 11. Therefore, in the air conditioner 1 in which the outdoor heat exchanger 4 is made of aluminum, galvanic corrosion of the connection parts 13 and the aluminum refrigerant pipes 11 can be suppressed for a long period of time.

[0124] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and includes various modifications without departing from the technical scope. For example, the above-described embodiments are not necessarily limited to those including all of the configurations described above. Furthermore, it is possible to replace part of the configuration of an embodiment with another configuration, or to add another configuration to the configuration of an embodiment. Furthermore, it is also possible to add other configurations to, delete configurations from, or replace part of the configuration of an embodiment.

[0125] For example, the air conditioner 1 can also be provided with a receiver, an oil separator, a dryer, etc. on the refrigerant circuit 10. The air conditioner 1 can also be provided with an injection circuit for injecting refrigerant at an intermediate pressure into the compressor 2. The injection circuit is connected to the compressor 2 from the condenser, bypassing the evaporator. A structure in which the connection portion 13, where the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 are connected, is covered with a cover 20, or an aluminum refrigerant pipe 11 with a sacrificial corrosion protection layer 15 formed thereon, can be provided in any section of the refrigerant circuit 10.

[0126] Furthermore, the air conditioner 1 can be a package air conditioner, a home multi-air conditioner, a commercial air conditioner, a commercial multi-air conditioner, a building multi-air conditioner, or the like, instead of the room air conditioner shown in Fig. 1 etc. In Fig. 2, 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. A structure in which the connection portion 13 connecting the aluminum refrigerant pipe 11 and the metal refrigerant pipe 12 is covered with a cover 20, or an aluminum refrigerant pipe 11 with a sacrificial corrosion protection layer 15 formed thereon, can be installed in any section of the refrigerant circuit of these air conditioners. [Explanation of symbols]

[0127] 1. Air conditioner 2 Compressor 3 Four-way valve 4 Outdoor heat exchanger 4a Main body 4b Subcooler 5 Expansion valve 6 Indoor heat exchanger 7 Accumulator 8 Outdoor ventilation fan 9 Indoor ventilation fan 10 Refrigerant circuit 11 Aluminum refrigerant pipe 12 Metal refrigerant pipe 13 Connection 14 Joining metal 15 Sacrificial corrosion protection layer 16 Strainer 17 Bend section 18 Liquid side service valve 19 Gas side service valve 20 Cover 21 Distributor 100 Outdoor unit 101 Bottom base 105 Partition 110 Heat exchanger room 120 Machine room 200 indoor unit 300 Connecting piping 400 Remote Control

Claims

1. The device includes a connection point where an aluminum refrigerant pipe, made of aluminum or an aluminum-containing metal, is positioned vertically below a metal refrigerant pipe, made of a metal with a lower ionization tendency than aluminum. The outer surface of the aforementioned connection part is covered with a cover. A sacrificial corrosion protection layer is formed on the outer surface of the aforementioned aluminum refrigerant pipe. An air conditioner in which the surface area of ​​the aluminum refrigerant pipe is larger than the surface area of ​​the metal refrigerant pipe.

2. An air conditioner according to claim 1, The aforementioned air conditioner comprises a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve, a service valve attached to the outdoor unit, and an indoor heat exchanger, all connected via refrigerant pipes in a refrigerant circuit. The aforementioned connection portion is provided in one or more of the following sections: the section between the outdoor heat exchanger and the expansion valve, the section between the expansion valve and the service valve, or the section between the four-way valve and the outdoor heat exchanger.

3. An air conditioner according to claim 2, The aforementioned aluminum refrigerant pipe is a refrigerant pipe connected to the heat transfer tube of the outdoor heat exchanger. An air conditioner in which the aluminum refrigerant pipe and the metal refrigerant pipe are connected vertically, substantially parallel to the vertical direction, or inclined diagonally from the vertical direction.

4. An air conditioner according to claim 1, The aforementioned metal refrigerant pipe is a copper refrigerant pipe made of copper or a metal containing copper, or a stainless steel refrigerant pipe made of stainless steel, in an air conditioner.

5. An air conditioner according to claim 1, An outdoor heat exchanger having aluminum heat transfer tubes and aluminum fins, or an indoor heat exchanger having aluminum heat transfer tubes and aluminum fins, The aforementioned aluminum refrigerant pipe is a refrigerant pipe connected to the aforementioned aluminum heat transfer tube, An air conditioner in which the sum of the surface areas of the aluminum refrigerant pipe, the aluminum heat transfer pipe, and the aluminum fins is 10 times or more the surface area of ​​the metal refrigerant pipe.

6. An air conditioner according to claim 1, The sacrificial corrosion protection layer is formed of zinc or a zinc-aluminum alloy in the air conditioner.

7. An air conditioner according to claim 1, An air conditioner having a sacrificial corrosion protection layer with a thickness of 75 μm or more.

8. An air conditioner according to claim 1, The aforementioned cover is a heat-shrinkable tube for an air conditioner.

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