Air conditioning apparatus

Abstract

To provide an air conditioning apparatus capable of achieving optimal design according to target specifications of respective heat exchangers of an indoor unit and an outdoor unit.SOLUTION: The air conditioning apparatus includes: an indoor unit including an indoor heat transfer tube formed of aluminum or an aluminum alloy, the indoor heat transfer tube being connected to an indoor connection pipe formed of aluminum or an aluminum alloy; and an outdoor unit including an outdoor heat transfer tube made of aluminum or an aluminum alloy, the outdoor heat transfer tube being connected to an outdoor connection pipe made of aluminum or an aluminum alloy. The indoor heat transfer tube includes an indoor heat exchange portion in which a plurality of indoor heat transfer plates are provided, and an indoor joint portion which is larger than an inner diameter of the indoor heat exchange portion and into which the indoor connection pipe is inserted. The outdoor heat transfer tube includes an outdoor heat exchange portion provided with a plurality of outdoor heat transfer plates, and an outdoor joint portion having an inner diameter larger than an inner diameter of the outdoor heat exchange portion and into which the outdoor connection pipe is inserted, a ratio of an inner diameter of the indoor joint portion to an inner diameter of the indoor heat exchange portion being larger than a ratio of an inner diameter of the outdoor joint portion to an inner diameter of the outdoor heat exchange portion.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an air conditioning apparatus. [Background technology]

[0002] The heat exchangers in the indoor and outdoor units of air conditioners generally use copper pipes as heat transfer tubes, but to reduce costs, the use of aluminum pipes made of aluminum or aluminum alloys is increasing.The multiple heat transfer plates (fins) attached to the outer periphery of the heat transfer tubes are made of aluminum or aluminum alloys, so heat exchangers that use aluminum pipes as heat transfer tubes are called all-aluminum heat exchangers.

[0003] The heat transfer tubes of the heat exchanger are connected to the piping through which the refrigerant flows. The connection structure between the heat transfer tubes and the piping is such that the piping is inserted into the heat transfer tube and fixed by brazing. In all-aluminum heat exchangers, the heat transfer tubes are made of aluminum, so they are weak and the connection parts need to be reinforced.

[0004] By lengthening the overlapping portion between the heat transfer tube and the piping, the strength of the connection portion can be ensured. However, when the overlapping portion is lengthened, the brazing portion becomes longer, requiring more brazing material and increasing the time required for the brazing process. Therefore, a structure has been proposed that can ensure the strength of the connection portion without lengthening the brazing portion (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-170142 Summary of the Invention [Problem to be solved by the invention]

[0006] An important design issue is to establish (optimize) the structural dimensions of a heat exchanger that can achieve both quality and productivity, but achieving both is extremely difficult with an all-aluminum heat exchanger.

[0007] However, the quality required for the heat exchanger of the indoor unit and the outdoor unit is not necessarily the same. For the indoor unit, we focused on prioritizing quieter refrigerant flow noise during operation, while for the outdoor unit, we focused on productivity (workability).

[0008] Therefore, an object of the present invention is to provide an air conditioner that achieves both the required quality and productivity. [Means for solving the problem]

[0009] In view of the above problems, the present invention provides an indoor unit including an indoor heat transfer tube made of aluminum or an aluminum alloy, at least a part of which is connected to an indoor connection pipe made of aluminum or an aluminum alloy; an outdoor unit including an outdoor heat transfer tube made of aluminum or an aluminum alloy, at least a portion of which is connected to an outdoor connection pipe made of aluminum or an aluminum alloy; Including, The indoor heat transfer tube has an indoor heat exchange section having a plurality of indoor heat transfer plates provided on an outer periphery thereof, and an indoor joint section having an inner diameter larger than the indoor heat exchange section and into which the indoor connection pipe is inserted; The outdoor heat transfer pipe has an outdoor heat exchange section having a plurality of outdoor heat transfer plates provided on an outer periphery thereof, and an outdoor joint section having an inner diameter larger than the outdoor heat exchange section and into which the outdoor connection pipe is inserted, An air conditioner is provided in which the ratio of the inner diameter of the indoor joint portion to the inner diameter of the indoor heat exchange portion is greater than the ratio of the inner diameter of the outdoor joint portion to the inner diameter of the outdoor heat exchange portion. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an air conditioner that achieves both the required quality and productivity. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an air conditioning apparatus. [Figure 2] 3A and 3B are enlarged views of the exterior of an indoor heat exchanger provided in the indoor unit and a portion thereof; [Figure 3] A diagram showing a first example of connecting an indoor heat transfer tube and an indoor connection pipe. [Figure 4] 2A and 2B are diagrams showing the appearance of an outdoor heat exchanger provided in the outdoor unit and an enlarged view of a portion thereof; [Figure 5] FIG. 10 is a diagram showing an example of connecting an outdoor heat transfer pipe and an outdoor connection pipe. [Figure 6] A diagram showing a second example of connecting an indoor heat transfer tube and an indoor connection pipe. DETAILED DESCRIPTION OF THE INVENTION

[0012] Fig. 1 is a diagram showing an example of the configuration of an air conditioner. The air conditioner 10 includes an indoor unit 11 installed in the space (indoors) to be air-conditioned, and an outdoor unit 20 installed outdoors. The air conditioner 10 adjusts the temperature, humidity, etc. of the indoor air by circulating a refrigerant between the indoor unit 11 and the outdoor unit 20 and exchanging heat with the indoor air.

[0013] The indoor unit 11 and the outdoor unit 20 may each be configured with two or more units, and two or more indoor units 11 may be connected to one outdoor unit 20. Hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs) can be used as refrigerants. Examples of HFCs include R410A and R32. Examples of HFOs include R1234yf.

[0014] The indoor unit 11 communicates with the remote control and receives various signals such as operation commands, stop commands, commands to change the set temperature, commands to change the operation mode, etc. The indoor unit 11 is connected to the outdoor unit 20 via a communication line and works together with the outdoor unit 20 to condition the air in the room.

[0015] The indoor unit 11 starts up upon receiving an operation command from the remote control and instructs the outdoor unit 20 to start up. The indoor unit 11 and the remote control may be connected by a communication line, or may be configured to communicate wirelessly. After starting up, the outdoor unit 20 adjusts the compressor rotation speed and expansion valve opening, etc., and controls the amount of refrigerant circulating, etc., so that the indoor temperature, etc., becomes the set temperature, etc.

[0016] The indoor unit 11 includes an indoor heat exchanger 12, an indoor fan 13, and an indoor fan motor 14. The indoor fan 13 is driven by the indoor fan motor 14, takes in indoor air, and sends it to the indoor heat exchanger 12. The indoor heat exchanger 12 has an indoor heat transfer tube inside which a refrigerant flows, and is configured so that the sent air comes into contact with the surface of the indoor heat transfer tube and exchanges heat. The air that has exchanged heat in the indoor heat exchanger 12 is discharged into the room.

[0017] The indoor unit 11 may also be equipped with various sensors for detecting the indoor temperature and the like, an indoor expansion valve, and the like.

[0018] The outdoor unit 20 includes a compressor 21, an accumulator 22, a four-way valve 23, an outdoor expansion valve 24, an outdoor heat exchanger 25, an outdoor fan 26 as a blower, and an outdoor fan motor 27. The compressor 21 is, for example, a rotary compressor or a scroll compressor, and is driven by a compressor motor to compress low-pressure gas refrigerant and discharge it as high-pressure gas refrigerant. The accumulator 22 is a container for storing liquid return during transient periods and adjusts the refrigerant to an appropriate quality. Quality is the proportion of steam in wet steam, which indicates the mixture state of steam and microdroplets.

[0019] The four-way valve 23 is a valve that switches the refrigerant flow path depending on the operating state (operating mode) of the air conditioner 10. The operating modes include cooling mode, heating mode, and fan mode. The outdoor expansion valve 24 is a valve that reduces the pressure of high-pressure refrigerant and expands it. The outdoor fan 26 is driven by an outdoor fan motor 27, takes in outdoor air, and sends it to the outdoor heat exchanger 25. The outdoor heat exchanger 25 has an outdoor heat transfer tube inside which the refrigerant flows, and is configured so that the sent air comes into contact with the surface of the outdoor heat transfer tube and exchanges heat. The air that has exchanged heat in the outdoor heat exchanger 25 is discharged outdoors.

[0020] The outdoor unit 20 further includes a control device 28. The control device 28 is connected to the compressor 21, the four-way valve 23, the outdoor expansion valve 24, the indoor fan motor 14, and the outdoor fan motor 27, and controls these. Specifically, it controls the rotation speed of the compressor motor, the opening of the outdoor expansion valve 24, and the rotation speeds of the indoor fan motor 14 and the outdoor fan motor 27. In order to control these, various sensors, such as a sensor that detects the outdoor air temperature, are also attached to the outdoor unit 20. The control device 28 controls these based on information detected by the various sensors.

[0021] The control device 28 may be implemented in the indoor unit 11 instead of only in the outdoor unit 20, or may be implemented in both the indoor unit 11 and the outdoor unit 20 with its functions divided into two.

[0022] For example, during heating operation, the indoor heat exchanger 12 is used as a condenser, and the outdoor heat exchanger 25 is used as an evaporator. Therefore, the control device 28 circulates the refrigerant sealed in the system in the order of the compressor 21, four-way valve 23, indoor heat exchanger 12, outdoor expansion valve 24, outdoor heat exchanger 25, four-way valve 23, accumulator 22, and compressor 21, as shown by the arrows.

[0023] The compressor 21 compresses a low-temperature, low-pressure gaseous refrigerant (refrigerant gas) and discharges it as a high-temperature, high-pressure refrigerant gas. The indoor heat exchanger 12 exchanges heat with indoor air to cool and condense the refrigerant gas. The outdoor expansion valve 24 reduces the pressure of the liquid refrigerant. The opening of the outdoor expansion valve 24 is adjusted by a control device 28 so that an appropriate amount of liquid remains. The outdoor heat exchanger 25 exchanges heat with outdoor air and evaporates the refrigerant. The refrigerant is then sent to the accumulator 22 through a four-way valve 23 and returned to the compressor 21.

[0024] 2A and 2B are diagrams showing the appearance of the indoor heat exchanger 12 provided in the indoor unit 11 and an enlarged view of a portion thereof. Fig. 2A is a diagram showing the appearance of the indoor heat exchanger 12, Fig. 2B is a diagram showing an enlarged view of the circled portion (portion A) in Fig. 2A, and Fig. 2C is a diagram showing an enlarged view of the circled portion (portion B) in Fig. 2A. As shown in Fig. 2A, the indoor heat exchanger 12 is a generally U-shaped heat exchanger that includes multiple indoor heat transfer tubes 30, a U-shaped indoor U-junction pipe 31 that connects the indoor heat transfer tubes 30, and multiple heat transfer plates (fins) provided on the outer periphery of the linearly extending indoor heat transfer tubes 30. The indoor heat exchanger 12 is arranged to surround the indoor fan 13.

[0025] The indoor heat transfer tubes 30 are connected to one another by one or more indoor U-shaped connecting pipes 31 to form a flow path through which the refrigerant flows. An indoor connecting pipe 32 is connected to one end and the other end of the indoor heat transfer tubes 30 connected by one or more indoor U-shaped connecting pipes 31.

[0026] Therefore, a refrigerant is supplied from an indoor connection pipe 32 connected to one end of a plurality of indoor heat transfer pipes 30 connected by one or more indoor U-shaped connection pipes 31, and the refrigerant is caused to flow toward the other end, where heat exchange occurs between the refrigerant and the air, and the refrigerant is discharged from the other end to the indoor connection pipe 32 connected to the other end.

[0027] The number of refrigerant flow paths within the indoor heat exchanger 12 is not limited to one, and two or more flow paths may be formed. In this case, two or more indoor connecting pipes 32 are connected to the refrigerant inlet side and two or more indoor connecting pipes 32 are connected to the outlet side, and collecting pipes can be used for the two or more indoor connecting pipes 32 on the inlet side and the outlet side, respectively. Also, a branch pipe may be provided on each of the two refrigerant pipes connecting the indoor unit 11 and the outdoor unit 20, and the two or more indoor connecting pipes 32 may be connected to the branch pipes.

[0028] 2(a) and 2(b), the indoor heat transfer tube 30 has an indoor heat exchanger section 33 with fins provided on its outer periphery, and an indoor joint section 34 into which the end of the indoor connection pipe 32 is inserted. Therefore, the inner diameter of the indoor joint section 34, where the end of the indoor connection pipe 32 is inserted, is larger than the inner diameter of the indoor heat exchanger section 33.

[0029] 2(c), for example, two ends of an indoor U-shaped connecting pipe 31 are inserted into the indoor joint portions 34 of two adjacent indoor heat transfer tubes 30, and the two indoor heat transfer tubes 30 are connected by the indoor U-shaped connecting pipe 31. Note that the two indoor heat transfer tubes 30 connected by one indoor U-shaped connecting pipe 31 are not limited to two adjacent indoor heat transfer tubes 30. The two ends of the indoor U-shaped connecting pipe 31 also have the same shape as the end of the indoor connecting pipe 32. Therefore, the inner diameter of the indoor joint portions 34 of each of the two indoor heat transfer tubes 30, at which the two ends of the indoor U-shaped connecting pipe 31 are inserted, is larger than the inner diameter of the indoor heat exchange portions 33 of each of the two indoor heat transfer tubes 30.

[0030] Fig. 3 is a diagram showing a first example of the connection structure between the indoor heat transfer tube 30 and the indoor connection pipe 32. Fig. 3(a) is a cross-sectional view of part A showing the indoor connection pipe 32 inserted into the indoor heat transfer tube 30, and Fig. 3(b) is a cross-sectional view of part A of the indoor heat transfer tube 30. Note that the cross-sectional view of part B showing the indoor U-shaped connection pipe 31 inserted into the indoor heat transfer tube 30 and the cross-sectional view of part B of the indoor heat transfer tube 30 are similar to the cross-sectional views shown in Figs. 3(a) and 3(b).

[0031] The indoor heat exchange section 33 is a section having a plurality of fins provided on its outer periphery. The fins extend perpendicular to the direction of extension of the indoor heat transfer tube 30 and are arranged approximately parallel at regular intervals. The indoor heat transfer tube 30 may be a tube with a smooth inner surface and a constant inner diameter, or a tube with spiral grooves on its inner surface. The grooves on the inner surface increase the internal surface area compared to a tube with a smooth inner surface, and the grooves allow a uniform liquid film to form inside the tube, improving the heat transfer performance inside the tube. In the case of a tube with grooves on its inner surface, the diameter of the approximately circular opening formed by the part that protrudes most radially toward the center of the tube is defined as the inner diameter of the tube.

[0032] The indoor joint 34 is formed by expanding the end of the indoor heat transfer tube 30. An example of the expanding process is swaging, which is a cold forging process in which a rotating die is used to hammer and reduce the outer diameter of a round bar or pipe material.

[0033] The indoor joint portion 34 has a first indoor expanding diameter portion 35 that is hollow inside, connected to the indoor heat exchange portion 33, and has a diameter that expands from one end to the other end, a second indoor expanding diameter portion 36 that is hollow inside, connected to the first indoor expanding diameter portion 35, has a larger inner diameter than the indoor heat exchange portion 33, and has a diameter that does not change from one end to the other end, and a third indoor expanding diameter portion 37 that is hollow inside, connected to the second indoor expanding diameter portion 36, and has a diameter that expands from one end to the other end.

[0034] The indoor connection pipe 32 is inserted into the second indoor enlarged diameter section 36 via the third indoor enlarged diameter section 37. After the indoor connection pipe 32 is inserted into the second indoor enlarged diameter section 36, brazing material is melted using a heating means such as a burner through an opening 38 between the third indoor enlarged diameter section 37 and the indoor connection pipe 32 and poured between the second indoor enlarged diameter section 36 and the indoor connection pipe 32. The brazing material is then solidified by natural cooling, thereby joining (brazing) the indoor heat transfer tube 30 and the indoor connection pipe 32. Aluminum brazing material can be used as the brazing material. The indoor connection pipe 32 shown in Figure 3(a) is an indoor connection pipe whose diameter does not change between the tip located at the end on the indoor heat transfer tube 30 side and the remaining portion.

[0035] Here, as shown in Figure 3(b), the inner diameter of the indoor heat exchange section 33 of the indoor heat transfer tube 30 is D1, the inner diameter of the second indoor expansion section 36 of the indoor joint section 34 is D2, and as shown in Figure 3(a), the inner diameter of the indoor connection pipe 32 is D3, and the outer diameter of the indoor connection pipe 32 is D4.

[0036] The indoor heat exchanger 33 is required to be designed to suppress refrigerant flow noise in order to improve quality (customer satisfaction).

[0037] Refrigerant flow noise is likely to occur in locations where there is a large change in flow resistance. For example, in locations where the flow path is locally narrow, such as in small-diameter sections of piping. For this reason, it is necessary to avoid structures in which the indoor heat transfer tube 30 and the indoor connecting piping 32 have narrow inner diameters as much as possible. Furthermore, at the indoor joint 34 connecting the indoor heat transfer tube 30 and the indoor connecting piping 32, it is desirable to design the change in the inner diameter D1 of the indoor heat exchange section 33 of the indoor heat transfer tube 30 and the inner diameter D3 of the indoor connecting piping 32 as small as possible. In other words, D1 ≒ D3.

[0038] In addition, the inner diameter D2 of the second indoor expanded diameter portion 36 of the indoor joint portion 34 of the indoor heat transfer tube 30 needs to be larger than the outer diameter D4 of the indoor connecting pipe 32. However, the larger the inner diameter D2 of the second indoor expanded diameter portion 36, the more likely it is that cracks will occur during the pipe expansion process. Therefore, it is important that the inner diameter D2 for suppressing refrigerant flow noise be a dimension that achieves both a reduction in refrigerant flow noise and ease of pipe expansion.

[0039] Changes in flow path resistance can also occur between the indoor heat transfer tube 30 and the indoor U-shaped connecting pipe 31. Therefore, if the inner diameters of the two ends of the indoor U-shaped connecting pipe 31 are D3, the same as the inner diameter of the indoor connecting pipe 32, then it is desirable to design it so that the above-mentioned relationship D1 ≒ D3 holds. Furthermore, if the outer diameter of the indoor U-shaped connecting pipe 31 is D4, the same as the outer diameter of the indoor connecting pipe 32, then D2 needs to be larger than D4, but it is important that D2 be a dimension that achieves both reduction in refrigerant flow noise and ease of pipe expansion.

[0040] Thus, in order to reduce refrigerant flow noise, it is desirable to design the flow path so that the change in resistance is small both between the indoor heat transfer tube 30 and the indoor connecting pipe 32 and between the indoor heat transfer tube 30 and the indoor U-shaped connecting pipe 31. However, because the refrigerant flow noise is louder between the indoor heat transfer tube 30 and the indoor connecting pipe 32, the design may be such that the change in resistance of the flow path is small only between the indoor heat transfer tube 30 and the indoor connecting pipe 32. Furthermore, the indoor heat transfer tube 30 and the indoor connecting pipe 32 are connected at two points, the refrigerant inlet and outlet, and because the refrigerant flow noise is louder on the outlet side, the design may be such that the change in resistance of the flow path is small only on the outlet side.

[0041] Fig. 4 is a diagram showing the appearance of the outdoor heat exchanger 25 provided in the outdoor unit 20 and an enlarged view of a portion thereof. Fig. 4(a) shows the appearance of the outdoor heat exchanger 25, and Fig. 4(b) is a diagram showing an enlarged view of the circled portion (portion C) in Fig. 4(a). As shown in Fig. 4(a), the outdoor heat exchanger 25 includes a plurality of outdoor heat transfer tubes 40, a U-shaped outdoor U-junction pipe 41 connecting two outdoor heat transfer tubes 40, and a plurality of heat transfer plates (fins) provided on the outer periphery of the linearly extending outdoor heat transfer tubes 40, and arranged to surround the interior.

[0042] The outdoor heat transfer pipes 40 are connected to one another by outdoor U-shaped connection pipes 41 to form a flow path through which the refrigerant flows. An outdoor connection pipe 42 is connected to one end and the other end of the outdoor heat transfer pipes 40 connected by the outdoor U-shaped connection pipes 41.

[0043] Therefore, refrigerant is supplied from the outdoor connection pipe 42 connected to one end of multiple outdoor heat transfer pipes 40 connected by the outdoor U-shaped connection pipe 41, and is caused to flow toward the other end, where heat exchange occurs between the refrigerant and the air, and the refrigerant is discharged from the other end to the outdoor connection pipe 42 connected to the other end.

[0044] 4(b), the outdoor heat transfer pipe 40 has an outdoor heat exchange section 43 provided with fins on its outer periphery, and an outdoor joint section 44 into which the end of the outdoor connection pipe 42 or the end of the outdoor U-shaped connection pipe 41 is inserted. Therefore, the inner diameter of the portion of the outdoor joint section 44 into which the end of the outdoor connection pipe 42 or the end of the outdoor U-shaped connection pipe 41 is inserted is larger than the inner diameter of the outdoor heat exchange section 43.

[0045] 5A and 5B are diagrams showing an example of a connection structure between the outdoor heat transfer pipe 40 and the outdoor connection pipe 42. Fig. 5A is a cross-sectional view of part C showing the outdoor connection pipe 42 inserted into the outdoor heat transfer pipe 40, and Fig. 5B is a cross-sectional view of part C of the outdoor heat transfer pipe 40.

[0046] The outdoor heat exchange section 43 is a section with multiple fins on its outer periphery. The multiple fins extend perpendicular to the direction of extension of the outdoor heat transfer tube 40 and are arranged approximately parallel at regular intervals. The outdoor heat transfer tube 40 may be a tube with a smooth inner surface and a constant inner diameter, or a tube with spiral grooves on its inner surface. As with the indoor heat transfer tube 30, providing grooves on the inner surface increases the internal surface area compared to a tube with a smooth inner surface. The grooves allow a uniform liquid film to form inside the tube, improving the heat transfer performance inside the tube. Note that in the case of a tube with grooves on its inner surface, the diameter of the approximately circular opening formed by the portion that protrudes most radially toward the center of the tube is defined as the inner diameter of the tube.

[0047] The outdoor joint portion 44 is formed by expanding the end portion of the outdoor heat transfer pipe 40 by swaging or other pipe expansion processing.

[0048] The outdoor joint 44 has a first outdoor expansion section 45 that is hollow inside, connected to the outdoor heat exchange section 43, and has a diameter that expands from one end to the other end, a second outdoor expansion section 46 that is hollow inside, connected to the first outdoor expansion section 45, has a larger inner diameter than the outdoor heat exchange section 43, and has a diameter that does not change from one end to the other end, and a third outdoor expansion section 47 that is hollow inside, connected to the second outdoor expansion section 46, and has a diameter that expands from one end to the other end.

[0049] The outdoor connection pipe 42 is inserted into the second outdoor enlarged diameter section 46 via the third outdoor enlarged diameter section 47. After the outdoor connection pipe 42 is inserted into the second outdoor enlarged diameter section 46, brazing material is melted by heating means such as a burner through a wide opening 48 between the third outdoor enlarged diameter section 47 and the outdoor connection pipe 42, and poured between the second outdoor enlarged diameter section 46 and the outdoor connection pipe 42, where it is solidified by natural cooling, thereby brazing the outdoor heat transfer pipe 40 and the outdoor connection pipe 42. The outdoor connection pipe 42 shown in Figure 5(a) is an outdoor connection pipe whose diameter does not change between the tip located at the end on the outdoor heat transfer pipe 40 side and the remaining portion.

[0050] Here, as shown in Figure 5(b), the inner diameter of the outdoor heat exchange section 43 is D5, the inner diameter of the second outdoor expansion section 46 of the outdoor joint section 44 is D6, and as shown in Figure 5(a), the inner diameter of the outdoor connection pipe 42 is D7, and the outer diameter of the outdoor connection pipe 42 is D8.

[0051] The outdoor unit 20 is installed outdoors and includes, in the same housing, a device that generates noise such as the motor noise of the compressor 21 that exceeds the refrigerant flow noise of the outdoor heat exchanger 25. For this reason, customers tend to tolerate the refrigerant flow noise as it is smaller than the motor noise of the compressor 21 and the motor noise itself is generated outdoors, and is therefore not an annoying noise.

[0052] On the other hand, when expanding the end of the outdoor heat transfer tube 40 to form the outdoor joint 44, if the degree of expansion is increased, i.e., if the inner diameter D6 of the second outdoor expanded diameter portion 46 is increased, cracks may occur. The occurrence of cracks results in product defects and leads to an increase in the defect rate.

[0053] To prevent cracks from occurring, it is necessary to reduce the degree of pipe expansion. However, if the degree of pipe expansion is reduced, it will not be possible to minimize the change in the inner diameter D1 of the indoor heat exchange section 33 of the indoor heat transfer pipe 30 and the inner diameter D3 of the indoor connecting pipe 32, as in the indoor heat exchanger 12. In other words, this will result in a design that generates refrigerant flow noise.

[0054] Because the outdoor heat exchanger 25 tends to tolerate refrigerant flow noise, there is no need to make the inner diameter D5 of the outdoor heat exchange section 43 and the inner diameter D7 of the outdoor connection pipe 42 approximately equal, as with the indoor heat exchanger 12. Therefore, the outdoor heat exchanger 25 allows the degree of expansion of the end of the outdoor heat transfer pipe 40 to be reduced. This allows for stable processing, reduces the occurrence of cracks, lowers the reject rate, and improves productivity (processability). Furthermore, if the degree of expansion of the end of the outdoor heat transfer pipe 40 is reduced, the outer diameter of the outdoor connection pipe 42 to be inserted therein can be reduced, thereby reducing manufacturing costs.

[0055] Therefore, the indoor heat exchanger 12 is designed for indoor use with an emphasis on quality (low noise) with enhanced quieting of refrigerant flow noise, while the outdoor heat exchanger 25 is designed for outdoor use with an emphasis on productivity and cost since refrigerant flow noise is more tolerable than in the indoor unit 11, making it possible to achieve an optimal design that balances quality, productivity, and cost for the required specifications of each heat exchanger.

[0056] In this case, the ratio D2 / D1 of the inner diameter D2 of the indoor joint portion 34 to the inner diameter D1 of the indoor heat exchange portion 33 is greater than the ratio D6 / D5 of the inner diameter D6 of the outdoor joint portion 44 to the inner diameter D5 of the outdoor heat exchange portion 43, i.e., the correlation D2 / D1>D6 / D5 is established. The ratio D2 / D1 is the indoor inner diameter ratio, and the ratio D6 / D5 is the outdoor inner diameter ratio.

[0057] The inner diameter D1 of the indoor heat exchange section 33 and the inner diameter D5 of the outdoor heat exchange section 43 can be made approximately the same diameter (D1 ≒ D5). In the outdoor heat exchange section 43, which tends to have more tolerable refrigerant flow noise than the indoor heat exchange section 33, the inner diameter D6 of the outdoor joint section 44 (the inner diameter of the second outdoor expanded diameter section 46 of the outdoor joint section 44) can be made smaller than the inner diameter D2 of the indoor joint section 34 (the inner diameter of the second indoor expanded diameter section 36 of the indoor joint section 34), giving priority to reducing the incidence of cracks during expansion of the outdoor heat transfer tube 40. In other words, D2 > D6. From these factors, the above-mentioned relationship D2 / D1 > D6 / D5 holds.

[0058] Since the outdoor joint 44 can be expanded to a smaller extent than the indoor joint 34, the outer diameter D8 of the outdoor connection pipe 42 inserted into the outdoor joint 44 can be made smaller than the outer diameter D4 of the indoor connection pipe 32 inserted into the indoor joint 34. In other words, D4 > D8 holds.

[0059] This will be explained in more detail. If the processing dimensions of the indoor heat transfer tube 30 and the outdoor heat transfer tube 40 are D1 = 6 mm, D2 = 7.2 mm, D5 = 6 mm, and D6 = 6.5 mm, then D2 / D1 = 1.20 and D6 / D5 = 1.08, and the correlation D2 / D1 > D6 / D5 holds. Furthermore, if the outer diameter dimensions of the indoor connecting pipe 32 and the outdoor connecting pipe 42 are D4 = 7 mm and D8 = 6.35 mm, then the correlation D4 > D8 holds. Therefore, by using these expanded pipe structural dimensions, an optimal design can be achieved that prioritizes quality (low noise) for the indoor heat exchanger 12 and productivity and cost for the outdoor heat exchanger 25.

[0060] As shown in Figure 3(a), the indoor joint 34 can be connected to an indoor connection pipe 32 whose diameter does not change between the tip and the rest of the pipe. Similarly, as shown in Figure 5(a), the outdoor joint 44 can be connected to an outdoor connection pipe 42 whose diameter does not change between the tip and the rest of the pipe.

[0061] The indoor connection pipe 32 and the outdoor connection pipe 42 may be pipes whose tips, located at the ends on the indoor heat transfer pipe 30 side and the outdoor heat transfer pipe 40 side, have a smaller diameter than the remaining parts. Fig. 6 is a diagram showing an example of an indoor connection pipe 32 whose tip has a smaller diameter than the remaining parts. The indoor heat transfer pipe 30 has an indoor heat exchange section 33 and an indoor joint section 34, and the indoor joint section 34 has a first indoor expanded diameter section 35, a second indoor expanded diameter section 36, and a third indoor expanded diameter section 37.

[0062] The indoor connection pipe 32 has an indoor main pipe section 50 and an indoor small-diameter section 51, which is located at the end on the indoor heat transfer pipe 30 side and has a smaller diameter than the indoor main pipe section 50. In FIG. 6 , an outdoor reduced-diameter section is provided between the indoor main pipe section 50 and the indoor small-diameter section 51, whose diameter decreases from the indoor main pipe section 50 side to the indoor small-diameter section 51 side. The indoor small-diameter section 51 is formed at the tip of the indoor connection pipe 32 and has a substantially constant diameter. When the indoor connection pipe 32 having this structure is inserted into and joined to the indoor joint section 34, the outer surface of the portion of the indoor main pipe section 50 adjacent to the indoor small-diameter section 51 abuts the inner surface of the second indoor enlarged-diameter section 36 of the indoor joint section 34, and the indoor small-diameter section 51 can be inserted beyond the second indoor enlarged-diameter section 36 into the first indoor enlarged-diameter section 35 and further into the indoor heat exchange section 33.

[0063] The indoor heat transfer pipe 30 and the indoor connection pipe 32 can be joined by melting and pouring brazing material into the opening 38 between the third indoor expanded diameter portion 37 and the indoor main pipe portion 50 of the indoor connection pipe 32, and brazing the second indoor expanded diameter portion 36 to a portion of the indoor main pipe portion 50 adjacent to the indoor narrow diameter portion 51. Note that by inserting the indoor narrow diameter portion 51 into the indoor heat exchanger portion 33, the length of the overlapping portion between the indoor heat transfer pipe 30 and the indoor connection pipe 32 can be increased, thereby improving the joining strength. Note that narrow diameter portions such as the indoor narrow diameter portion 51 may also be provided at the ends of the indoor U-shaped connection pipe 31, the outdoor U-shaped connection pipe 41, and the outdoor connection pipe 42.

[0064] The inner diameter of the indoor joint 34 can be the inner diameter of the second indoor enlarged diameter section 36, but is not limited to this, and may be the inner diameter of the indoor joint 34 at a position corresponding to the tip of the indoor main pipe section 50 (including a pipe without a narrow diameter section) of the indoor connection piping 32, or may be the average value of the inner diameter of the indoor joint 34.

[0065] In addition, the inner diameter of the outdoor joint 44 may be the inner diameter of the second outdoor enlarged diameter section 46, but is not limited to this, and may be the inner diameter of the outdoor joint 44 at a position corresponding to the tip of the outdoor main pipe section (including a pipe without a narrow diameter section) of the outdoor connection piping 42, or may be the average value of the inner diameter of the outdoor joint 44.

[0066] Therefore, a correlation may be established in which the ratio of the inner diameter of the indoor joint portion 34 at a position corresponding to the tip of the indoor main pipe portion 50 to the inner diameter D1 of the indoor heat exchange portion 33 is greater than the ratio of the inner diameter of the outdoor joint portion 44 at a position corresponding to the tip of the outdoor main pipe portion to the inner diameter D5 of the outdoor heat exchange portion 43. A correlation may also be established in which the ratio of the average inner diameter of the indoor joint portion 34 to the inner diameter D1 of the indoor heat exchange portion 33 is greater than the ratio of the average inner diameter of the outdoor joint portion 44 to the inner diameter D5 of the outdoor heat exchange portion 43. A correlation may also be established in which the difference between the inner diameter D1 of the indoor heat exchange portion 33 and the inner diameter of the indoor main pipe portion 50 (i.e., the inner diameter D3 of the indoor connection pipe 32) is smaller than the difference between the inner diameter D5 of the outdoor heat exchange portion 43 and the inner diameter of the outdoor main pipe portion (i.e., the inner diameter D7 of the outdoor connection pipe 42). That is, |D1-D3|<|D5-D7|.

[0067] Like the indoor connection pipe 32, the indoor U-shaped connection pipe 31 has an indoor main pipe section and an indoor narrow diameter section if the tip located at the end on the indoor heat transfer pipe 30 side is a pipe with a smaller diameter than the other parts, and has an indoor main pipe section if the diameter of the tip and other parts does not change.Like the outdoor connection pipe 42, the outdoor U-shaped connection pipe 41 has an outdoor main pipe section and an outdoor narrow diameter section if the tip located at the end on the outdoor heat transfer pipe 40 side is a pipe with a smaller diameter than the other parts, and has an outdoor main pipe section if the diameter of the tip and other parts does not change.

[0068] Therefore, a correlation may be established in which the ratio of the inner diameter of the indoor joint portion 34 at a position corresponding to the tip of the indoor main pipe portion to the inner diameter D1 of the indoor heat exchange portion 33 is greater than the ratio of the inner diameter of the outdoor joint portion 44 at a position corresponding to the tip of the outdoor main pipe portion to the inner diameter D5 of the outdoor heat exchange portion 43. Also, a correlation may be established in which the ratio of the average inner diameter of the indoor joint portion 34 to the inner diameter D1 of the indoor heat exchange portion 33 is greater than the ratio of the average inner diameter of the outdoor joint portion 44 to the inner diameter D5 of the outdoor heat exchange portion 43. Also, a correlation may be established in which the difference between the inner diameter D1 of the indoor heat exchange portion 33 and the inner diameter of the indoor main pipe portion, i.e., the inner diameter of the indoor U-shaped connecting pipe 31, is smaller than the difference between the inner diameter D5 of the outdoor heat exchange portion 43 and the inner diameter of the outdoor main pipe portion, i.e., the inner diameter of the outdoor U-shaped connecting pipe 41.

[0069] Furthermore, a correlation may be established in which the outer diameter of the indoor main pipe section 50 of the indoor connecting pipe 32 is larger than the outer diameter of the outdoor main pipe section of the outdoor connecting pipe 42. A correlation may be established in which the outer diameter of the indoor main pipe section of the indoor U-shaped connecting pipe 31 is larger than the outer diameter of the outdoor main pipe section of the outdoor U-shaped connecting pipe 41.

[0070] As explained above, by providing the air conditioner of the present invention, it is possible to realize an optimal design that balances quality, productivity, and cost in accordance with the required specifications of each heat exchanger.

[0071] The air conditioning apparatus of the present invention has been described in detail using the above-mentioned embodiment, but the present invention is not limited to the above-mentioned embodiment and can be modified to include other embodiments, additions, changes, deletions, and other changes within the scope that can be conceived by a person skilled in the art, and any aspect is within the scope of the present invention as long as it achieves the functions and effects of the present invention.

[0072] Therefore, either or both of the indoor heat transfer tube 30 and the indoor connecting pipe 32, or the indoor heat transfer tube 30 and the indoor U-shaped connecting pipe 31 may be designed to reduce the change in flow resistance in order to suppress the above-mentioned refrigerant flow noise. [Explanation of symbols]

[0073] 10...Air conditioning equipment 11...Indoor unit 12…Indoor heat exchanger 13...Indoor fan 14...Indoor fan motor 20...Outdoor unit 21...Compressor 22...Accumulator 23...Four-way valve 24...Expansion valve 25...Outdoor heat exchanger 26...Outdoor fan 27...Outdoor fan motor 28...Control device 30...Indoor heat transfer tube 31...Indoor U-shaped connection pipe 32...Indoor connection piping 33...Indoor heat exchange section 34...Indoor joint 35...First indoor expansion section 36...Second indoor expansion section 37...Third indoor expansion section 38…Aperture 40...Outdoor heat exchanger tube 41...Outdoor U-shaped connection pipe 42...Outdoor connection piping 43...Outdoor heat exchange section 44...Outdoor joint 45...First outdoor expansion section 46...Second outdoor expansion section 47...Third outdoor expansion section 48…Aperture 50...Indoor main pipe section 51...Indoor narrow diameter section

Claims

1. an indoor unit including an indoor heat transfer tube made of aluminum or an aluminum alloy, at least a portion of the indoor heat transfer tube being connected to an indoor connection pipe made of aluminum or an aluminum alloy; an outdoor unit including an outdoor heat transfer tube made of aluminum or an aluminum alloy, at least a portion of the outdoor heat transfer tube being connected to an outdoor connection pipe made of aluminum or an aluminum alloy; Including, the indoor heat transfer tube has an indoor heat exchange section having a plurality of indoor heat transfer plates provided on an outer periphery thereof, and an indoor joint section having an inner diameter larger than the indoor heat exchange section and into which the indoor connection pipe is inserted; The outdoor heat transfer pipe has an outdoor heat exchange section having a plurality of outdoor heat transfer plates provided on an outer periphery thereof, and an outdoor joint section having an inner diameter larger than the outdoor heat exchange section and into which the outdoor connection pipe is inserted, An air conditioning apparatus, wherein a ratio of an inner diameter of the indoor joint portion to an inner diameter of the indoor heat exchange portion is greater than a ratio of an inner diameter of the outdoor joint portion to an inner diameter of the outdoor heat exchange portion.

2. an indoor unit including an indoor heat transfer tube made of aluminum or an aluminum alloy, at least a portion of the indoor heat transfer tube being connected to an indoor U-shaped connecting pipe made of aluminum or an aluminum alloy; an outdoor unit including an outdoor heat transfer tube made of aluminum or an aluminum alloy, at least a portion of which is connected to an outdoor U-shaped connecting pipe made of aluminum or an aluminum alloy; Including, the indoor heat transfer tube has an indoor heat exchange section having a plurality of indoor heat transfer plates provided on an outer periphery thereof, and an indoor joint section having an inner diameter larger than the indoor heat exchange section and into which the indoor U-shaped connection pipe is inserted; The outdoor heat transfer pipe has an outdoor heat exchange section having a plurality of outdoor heat transfer plates provided on an outer periphery thereof, and an outdoor joint section having an inner diameter larger than the outdoor heat exchange section and into which the outdoor U-shaped connection pipe is inserted, An air conditioning apparatus, wherein a ratio of an inner diameter of the indoor joint portion to an inner diameter of the indoor heat exchange portion is greater than a ratio of an inner diameter of the outdoor joint portion to an inner diameter of the outdoor heat exchange portion.

3. the indoor joint portion has a first indoor expanding diameter portion whose diameter expands from one end to the other end, and a second indoor expanding diameter portion that is continuous with the first indoor expanding diameter portion, is larger than the inner diameter of the indoor heat exchange portion, and has a diameter that does not change from one end to the other end; the outdoor joint portion has a first outdoor expanded diameter portion whose diameter expands from one end to the other end, and a second outdoor expanded diameter portion that is continuous with the first outdoor expanded diameter portion, is larger than the inner diameter of the outdoor heat exchange portion, and has a diameter that does not change from one end to the other end, The air conditioning apparatus according to claim 1 or 2, wherein a ratio of an inner diameter of the second indoor expansion portion to an inner diameter of the indoor heat exchange portion is greater than a ratio of an inner diameter of the second outdoor expansion portion to an inner diameter of the outdoor heat exchange portion.

4. the indoor connection pipe has an indoor main pipe portion and an indoor small diameter portion located at an end portion on the indoor heat transfer pipe side and having a smaller diameter than the indoor main pipe portion, or has the indoor main pipe portion, the outdoor connection pipe has an outdoor main pipe portion and an outdoor small diameter portion located at an end portion on the outdoor heat transfer pipe side and having a smaller diameter than the outdoor main pipe portion, or has the outdoor main pipe portion, The air conditioning apparatus of claim 1, wherein the ratio of the inner diameter of the indoor joint at a position corresponding to the tip of the indoor main pipe to the inner diameter of the indoor heat exchanger is greater than the ratio of the inner diameter of the outdoor joint at a position corresponding to the tip of the outdoor main pipe to the inner diameter of the outdoor heat exchanger.

5. the indoor U-shaped connection pipe has an indoor main pipe portion and an indoor small diameter portion located at an end portion on the indoor heat transfer pipe side and having a diameter smaller than that of the indoor main pipe portion, or has the indoor main pipe portion, The outdoor U-shaped connection pipe has an outdoor main pipe portion and an outdoor small diameter portion located at an end portion on the outdoor heat transfer pipe side and having a smaller diameter than the outdoor main pipe portion, or has the outdoor main pipe portion, The air conditioning apparatus of claim 2, wherein the ratio of the inner diameter of the indoor joint at a position corresponding to the tip of the indoor main pipe to the inner diameter of the indoor heat exchanger is greater than the ratio of the inner diameter of the outdoor joint at a position corresponding to the tip of the outdoor main pipe to the inner diameter of the outdoor heat exchanger.

6. The air conditioning apparatus according to claim 1 or 2, wherein a ratio of an average value of the inner diameter of the indoor joint portion to an inner diameter of the indoor heat exchange portion is greater than a ratio of an average value of the inner diameter of the outdoor joint portion to an inner diameter of the outdoor heat exchange portion.

7. the indoor connection pipe has an indoor main pipe portion and an indoor small diameter portion located at an end portion on the indoor heat transfer pipe side and having a smaller diameter than the indoor main pipe portion, or has the indoor main pipe portion, the outdoor connection pipe has an outdoor main pipe portion and an outdoor small diameter portion located at an end portion on the outdoor heat transfer pipe side and having a smaller diameter than the outdoor main pipe portion, or has the outdoor main pipe portion, The air conditioner according to claim 1 , wherein a difference between an inner diameter of the indoor heat exchanger and an inner diameter of the indoor main pipe is smaller than a difference between an inner diameter of the outdoor heat exchanger and an inner diameter of the outdoor main pipe.

8. the indoor U-shaped connection pipe has an indoor main pipe portion and an indoor small diameter portion located at an end portion on the indoor heat transfer pipe side and having a diameter smaller than that of the indoor main pipe portion, or has the indoor main pipe portion, The outdoor U-shaped connection pipe has an outdoor main pipe portion and an outdoor small diameter portion located at an end portion on the outdoor heat transfer pipe side and having a smaller diameter than the outdoor main pipe portion, or has the outdoor main pipe portion, The air conditioner according to claim 2 , wherein a difference between an inner diameter of the indoor heat exchanger and an inner diameter of the indoor main pipe is smaller than a difference between an inner diameter of the outdoor heat exchanger and an inner diameter of the outdoor main pipe.

9. The air conditioning apparatus according to claim 1 or 2, wherein an inner diameter of the indoor joint portion is larger than an inner diameter of the outdoor joint portion.

10. The air conditioner according to claim 1 , wherein the outer diameter of the indoor connection pipe is larger than the outer diameter of the outdoor connection pipe.

11. the indoor connection pipe has an indoor main pipe portion and an indoor small diameter portion located at an end portion on the indoor heat transfer pipe side and having a smaller diameter than the indoor main pipe portion, or has the indoor main pipe portion, the outdoor connection pipe has an outdoor main pipe portion and an outdoor small diameter portion located at an end portion on the outdoor heat transfer pipe side and having a smaller diameter than the outdoor main pipe portion, The air conditioning apparatus according to claim 1 , wherein an outer diameter of the indoor main pipe portion is larger than an outer diameter of the outdoor main pipe portion.

12. The air conditioning apparatus according to claim 2 , wherein an outer diameter of the indoor U-shaped connecting pipe is larger than an outer diameter of the outdoor U-shaped connecting pipe.

13. the indoor U-shaped connection pipe has an indoor main pipe portion and an indoor small diameter portion located at an end portion on the indoor heat transfer pipe side and having a diameter smaller than that of the indoor main pipe portion, or has the indoor main pipe portion, the outdoor U-shaped connection pipe has an outdoor main pipe portion and an outdoor small diameter portion located at an end portion on the outdoor heat transfer pipe side and having a smaller diameter than the outdoor main pipe portion, The air conditioning apparatus according to claim 2 , wherein an outer diameter of the indoor main pipe portion is larger than an outer diameter of the outdoor main pipe portion.

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