Air conditioner

Abstract

[Problem] To suppress refrigerant noise while utilizing an aluminum pipe for an indoor heat exchanger. [Solution] This air conditioner comprises: a heat transfer pipe which is formed of aluminum or an aluminum alloy and is provided in an indoor heat exchanger; and a connection pipe which is connected to the heat transfer pipe and at least a part of which is formed of aluminum or an aluminum alloy. A small-diameter part formed at an end of the connection pipe is inserted into the heat transfer pipe. The length of at least one of the small-diameter parts respectively inserted into two refrigerant inlet / outlet ports of the indoor heat exchanger is shorter than the length of a small-diameter part inserted into a refrigerant inlet / outlet port of an outdoor heat exchanger.

Description

air conditioner

[0001] The present invention relates to an air conditioner.

[0002] Copper pipes have traditionally been used in the heat exchangers of air conditioners, but because aluminum is cheaper than copper, there has been an increase in the use of aluminum pipes in the heat exchangers of outdoor units in recent years. Patent Document 1 discloses an outdoor heat exchanger that uses aluminum pipes.

[0003] Japanese Patent Application Laid-Open No. 2023-13765

[0004] At the connection between the connecting pipe that connects the indoor unit and the outdoor unit and the heat transfer pipe in the heat exchanger, a tube-reducing section formed on the end of the connecting pipe is inserted into the end of the heat transfer pipe. Because aluminum pipes need to be thicker than copper pipes, when aluminum pipes are used, the ratio of the inside diameter of the heat transfer pipe to the tube-reducing section is larger than that of copper pipes, which causes problems such as increased pressure loss and louder refrigerant noise.

[0005] The present invention has been made in consideration of such problems, and has an object to suppress refrigerant noise while using aluminum tubes in an indoor heat exchanger.

[0006] The present invention is an air conditioner comprising a heat transfer tube made of aluminum or an aluminum alloy and provided in an indoor heat exchanger; and a connecting pipe connected to the heat transfer tube and at least a portion of which is made of aluminum or an aluminum alloy, wherein a narrow-diameter portion formed at the end of the connecting pipe is inserted into the heat transfer tube, and the length of at least one of the narrow-diameter portions inserted into each of two refrigerant inlets and outlets of the indoor heat exchanger is shorter than the length of the narrow-diameter portion inserted into the refrigerant inlet and outlet of the outdoor heat exchanger.

[0007] The present invention is an air conditioner comprising a heat transfer tube made of aluminum or an aluminum alloy and provided in an indoor heat exchanger; and a connecting pipe connected to the heat transfer tube, at least a portion of which is made of aluminum or an aluminum alloy, wherein the heat transfer tube has a thick-diameter portion whose outer diameter is larger than the portion that overlaps the fin region of the indoor heat exchanger, and a thin-diameter portion formed at the end of the connecting pipe is inserted into the heat transfer tube, and the length of at least one of the thin-diameter portions inserted into each of two refrigerant inlets and outlets of the indoor heat exchanger is shorter than the length of the thick-diameter portion.

[0008] The present invention is an air conditioner comprising: a heat transfer tube made of aluminum or an aluminum alloy and provided in an indoor heat exchanger; and a connecting pipe inserted into the heat transfer tube, at least a portion of which is made of aluminum or an aluminum alloy, wherein the connecting pipe is inserted up to a portion overlapping a fin region of the indoor heat exchanger, and the length of the portion overlapping the fin region of at least one of the connecting pipes inserted into each of two refrigerant inlets and outlets of the indoor heat exchanger is shorter than the length of the portion overlapping the fin region of the connecting pipe inserted into the refrigerant inlet and outlet of the outdoor heat exchanger.

[0009] According to the present invention, refrigerant noise can be suppressed while using aluminum tubes in the indoor heat exchanger.

[0010] It is an external configuration diagram showing an air conditioner. It is a diagram showing a refrigerant circuit of the air conditioner. It is a diagram showing an indoor heat exchanger. It is a schematic cross-sectional view of a connection part between a heat transfer tube and a connection pipe. It is an enlarged view of a fixing member.

[0011] Fig. 1 is an external configuration diagram showing an air conditioner 1 according to this embodiment. The air conditioner 1 performs air conditioning by circulating a refrigerant in a refrigeration cycle. As shown in Fig. 1, the air conditioner 1 includes an indoor unit 2 installed indoors (the space to be air-conditioned), an outdoor unit 3 installed outdoors (outdoors), and a remote control 4 operated by a user.

[0012] The indoor unit 2 is equipped with a remote control communication unit 5. The remote control communication unit 5 transmits and receives predetermined signals to and from the remote control 4 via infrared communication or the like. For example, the remote control communication unit 5 receives signals such as an operation command, a stop command, a change in the set temperature, a change in the operation mode, or a timer setting from the remote control 4. Although not shown in Fig. 1 , the indoor unit 2 and the outdoor unit 3 are connected via refrigerant piping and also via a communication line.

[0013] Fig. 2 is a diagram showing the refrigerant circuit Q of the air conditioner 1 according to this embodiment. Note that the solid arrows shown in Fig. 2 indicate the flow of refrigerant during heating operation, and the dashed arrows shown in Fig. 2 indicate the flow of refrigerant during cooling operation.

[0014] In addition to the remote control communication unit 5, the indoor unit 2 is equipped with an indoor heat exchanger 6 and a cross-flow fan (also called a cross-flow fan or indoor fan) 7. In the indoor heat exchanger 6, heat exchange occurs between the refrigerant flowing through heat transfer tubes (described below) and the indoor air sent in from the cross-flow fan 7. The indoor heat exchanger 6 operates as a condenser or an evaporator depending on the switching of a four-way valve 13 (described below). The cross-flow fan 7 is installed near the indoor heat exchanger 6. The cross-flow fan 7 sends indoor air to the indoor heat exchanger 6 when driven by an indoor fan motor 8. The specific configuration of this indoor unit 2 will be described later.

[0015] The outdoor unit 3 includes a compressor 9, an outdoor heat exchanger 10, an outdoor fan 11, an outdoor expansion valve (expansion valve) 12, and a four-way valve 13. The compressor 9 compresses a low-temperature, low-pressure gas refrigerant by driving a compressor motor 14, and discharges it as a high-temperature, high-pressure gas refrigerant. In the outdoor heat exchanger 10, heat exchange occurs between the refrigerant flowing through the heat transfer tube and outside air sent in from the outdoor fan 11. The outdoor heat exchanger 10 operates as a condenser or an evaporator by switching the four-way valve 13.

[0016] As shown in Fig. 1, the outdoor fan 11 is installed near the outdoor heat exchanger 10. The outdoor fan 11 sends outside air to the outdoor heat exchanger 10 by driving an outdoor fan motor 11a. The outdoor expansion valve 12 has the function of reducing the pressure of the refrigerant condensed in the "condenser" (one of the outdoor heat exchanger 10 and the indoor heat exchanger 6). The refrigerant reduced in pressure in the outdoor expansion valve 12 is introduced to the "evaporator" (the other of the outdoor heat exchanger 10 and the indoor heat exchanger 6).

[0017] The four-way valve 13 switches the refrigerant flow path depending on the operating mode of the air conditioner 1. By switching the four-way valve 13, during cooling operation, the refrigeration cycle is established in which the refrigerant circulates in the order of the compressor 9, outdoor heat exchanger (condenser) 10, outdoor expansion valve 12, and indoor heat exchanger (evaporator) 6, as shown by the dashed arrow. Also, during heating operation, the four-way valve 13 switches the refrigeration cycle in which the refrigerant circulates in the order of the compressor 9, indoor heat exchanger (condenser) 6, outdoor expansion valve 12, and outdoor heat exchanger (evaporator) 10, as shown by the solid arrow. That is, in the refrigerant circuit Q in which the refrigerant circulates sequentially through the compressor 9, the "condenser," the outdoor expansion valve 12, and the "evaporator," one of the "condenser" and the "evaporator" is the outdoor heat exchanger 10, and the other is the indoor heat exchanger 6.

[0018] 3 is a schematic diagram of the indoor heat exchanger 6. The indoor heat exchanger 6 includes a plurality of fins 100, and a plurality of heat transfer tubes (hairpin pipes) 110 are provided so as to penetrate the fins 100. Furthermore, both ends of each heat transfer tube 110 are connected to the ends of adjacent heat transfer tubes 110 by return pipes 112. The return pipes 112 are formed in a U-shape. In this way, the plurality of heat transfer tubes 110 are connected in series by the return pipes 112, forming a long refrigerant flow path.

[0019] A connecting pipe 120 is inserted into and connected to each of the two refrigerant inlets 114 of the indoor heat exchanger 6 in the heat transfer pipe 110. In this embodiment, the heat transfer pipe 110 and the connecting pipe 120 are connected in a single path without any branching. The connecting pipe 120 is connected to the heat transfer pipe 110 by brazing. The heat transfer pipe 110, the return pipe 112, and the connecting pipe 120 are all made of aluminum or an aluminum alloy.

[0020] FIG. 4 is a schematic cross-sectional view of the connection portion between the heat transfer tube 110 and the connecting pipe 120. For both of the two refrigerant inlets and outlets 114 shown in FIG. 3 , the heat transfer tube 110 and the connecting pipe 120 are connected as shown in FIG. 4 . A secondary expansion section 1101, in which the inner diameter of the tube is expanded, is formed at the end of the heat transfer tube 110. After the heat transfer tube 110 is inserted into the through-holes provided in the fins 100, a primary expansion is performed over the entire length of the straight portion of the heat transfer tube 110, thereby closely contacting the fins 100. The end of the heat transfer tube 110 that does not overlap with the fins 100 in the longitudinal direction is then expanded (secondary expansion) to form the secondary expansion section 1101. That is, the secondary expansion section 1101 has a larger inner diameter than the portion that penetrates the fins 100, which has undergone primary expansion. Meanwhile, a reduced diameter section 1201, in which the inner diameter of the tube is reduced, is formed at the end of the connecting pipe 120. 4, the tube-reducing section 1201 is inserted into the refrigerant inlet / outlet 114 of the heat transfer tube 110, and brazing material is injected between the tube-reducing section 1201 and the refrigerant inlet / outlet 114, thereby connecting the heat transfer tube 110 and the connecting pipe 120. In other words, the tube-reducing section 1201 has a smaller inner diameter than the portion not inserted into the refrigerant inlet / outlet 114.

[0021] The tube contraction section 1201 is an example of a thin-diameter section of the connection pipe 120 that has a smaller (thinner) outer diameter than the portion of the connection pipe 120 that is not inserted into the refrigerant inlet / outlet 114. Here, the tube contraction section 1201 (thin-diameter section) is the range from a starting point 1202, where the inner diameter of the connection pipe 120 becomes smaller, to the end 121 of the connection pipe 120. The inner diameter at any position in the longitudinal direction of the tube contraction section 1201 is assumed to be equal to or smaller than the inner diameter at the starting point 1202. In other words, the inner diameter of the tube contraction section 1201 may or may not be uniform. For example, the inner diameter of the tube contraction section 1201 may become smaller as it approaches the end 121 of the tube contraction section 1201.

[0022] The secondary expansion section 1101 is an example of a thick-diameter section of the heat transfer tube 110, having a larger (thicker) inner diameter than the portion of the heat transfer tube 110 that penetrates the fins 100. Here, the secondary expansion section 1101 (thicker diameter section) is the range from a starting point 1102 where the inner diameter of the heat transfer tube 110 increases to the end (refrigerant inlet / outlet 114) of the heat transfer tube 110 in the portion of the heat transfer tube 110 that does not penetrate the fins 100 of the indoor heat exchanger 6. The inner diameter at any position in the longitudinal direction of the secondary expansion section 1101 is equal to or larger than the inner diameter at the starting point 1102. In other words, the inner diameter of the secondary expansion section 1101 may be uniform or may not be uniform. For example, the inner diameter of the secondary expansion section 1101 may increase as it approaches the end of the secondary expansion section 1101.

[0023] Here, the length L2 of the tube contraction section 1201 is shorter than the length L1 of the secondary tube expansion section 1101. Thus, the length of the connecting pipe 120 inserted into the heat transfer tube 110 is shortened. For example, the length L1 of the secondary tube expansion section 1101 is 11 mm, while the length L2 of the tube contraction section 1201 is 7 mm. Furthermore, in the outdoor heat exchanger 10, similar to the indoor heat exchanger 6, the tubes are connected by connecting the tube contraction section of the connecting pipe to the tube expansion section of the heat transfer tube. The length of the tube contraction section 1201 connected to the heat transfer tube 110 of the indoor heat exchanger 6 is shorter than the length of the tube contraction section inserted into the refrigerant inlet / outlet of the heat transfer tube of the outdoor heat exchanger 10. Because the inner diameter of the tube contraction section 1201 is smaller than the inner diameters of the connecting pipe 120 and the heat transfer tube 110, pressure loss increases and refrigerant noise increases. In contrast to this, in the air conditioner 1 of this embodiment, the length of the tube contraction section 1201 is shortened in this manner, thereby making it possible to suppress refrigerant noise.

[0024] On the other hand, the tube contraction section 1201 is inserted into the heat transfer tube 110 in the longitudinal direction thereof until it overlaps the fin region 1001 where the fins 100 are arranged. Here, the fin region 1001 is the range from one fin 100 at one end to the other fin 100 at the other end of the multiple fins 100. The length L3 of the portion 1203 of the tube contraction section 1201 that overlaps the fins 100 is shorter than the length of the portion of the connecting pipe inserted into the refrigerant inlet / outlet of the outdoor heat exchanger 10 that overlaps the fins 100. By ensuring the overlapping portion 1203 between the tube contraction section 1201 and the fins 100, the strength of the connection between the heat transfer tube 110 and the connecting pipe 120 can be maintained high. Furthermore, by ensuring a predetermined length for the tube contraction section 1201, it is possible to prevent the brazing material from flowing into the interior of the heat transfer tube 110.

[0025] As described above, the heat transfer tube 110 and the connecting pipe 120 are made of aluminum or an aluminum alloy, and therefore the tube contraction section 1201 and the secondary tube expansion section 1101 are also made of aluminum or an aluminum alloy.

[0026] Furthermore, because the connecting pipes 120 are made of aluminum or an aluminum alloy, they are thicker than the connecting pipes 120 made of copper. More specifically, the connecting pipes 120 of the air conditioner 1 include two types of pipes: a gas pipe through which a gas refrigerant flows, and a liquid pipe through which a liquid refrigerant or two-phase refrigerant flows. Of these, the connecting pipes 120 made of aluminum or an aluminum alloy and used as gas pipes are thicker than the connecting pipes made of copper and used as gas pipes. Similarly, the connecting pipes 120 made of aluminum or an aluminum alloy and used as liquid pipes are thicker than the connecting pipes made of copper and used as liquid pipes.

[0027] As shown in FIG. 3 , two connection pipes 120 connected to two refrigerant inlets and outlets 114 of the heat transfer pipe 110 are both fixed to the return pipe 112. In this embodiment, both connection pipes 120 are fixed to the return pipe 112a located closest to the refrigerant inlet and outlet 114 (the connection portion between the connection pipe 120 and the heat transfer pipe 110). When installing the air conditioner 1, the indoor unit 2 is installed indoors, and the outdoor unit 3 is installed outdoors. The connection pipe 120 of the indoor unit 2 is then bent appropriately by a service technician depending on the installation situation of the indoor unit 2. When a portion of the connection pipe 120 is bent, the resulting stress may cause the connection pipe 120 to break at the connection portion with the heat transfer pipe 110. In contrast, in this embodiment, the connection pipe 120 is fixed to the return pipe 112 from the connection portion with the heat transfer pipe 110 to the bent portion. Therefore, stress caused by bending is prevented from being transmitted to the connection portion between the heat transfer tube 110 and the connection pipe 120, and it is possible to prevent the connection pipe 120 from breaking at the connection portion. Furthermore, by fixing the connection pipe 120 to the return pipe 112a at a position closest to the refrigerant inlet / outlet 114, it is possible to reduce the routing space for the connection pipe 120.

[0028] Furthermore, the straight portion 120a of the connecting pipe 120 is fixed to the return pipe 112. This improves the workability when fixing the connecting pipe 120 to the return pipe 112.

[0029] The straight section 120a of the connection pipe 120 is covered with a covering member 130, and is fixed to the return pipe 112a by a fixing member 132 via the covering member 130. The covering member 130 is made of a material with a lower thermal conductivity than the connection pipe. Specifically, the covering member 130 is made of rubber or resin. This prevents heat exchange between the refrigerant flowing through the return pipe 112a and the refrigerant flowing through the portion of the connection pipe 120 fixed to the return pipe 112a.

[0030] The fixing member 132 is made of resin. In this way, the fixing member 132 is made of a material softer than aluminum. This prevents the connection pipe 120 and the return pipe 112 from being scraped by the fixing member 132. Furthermore, using resin ensures sufficient strength for fixing.

[0031] FIG. 5 is an enlarged view of the fixing member 132. The fixing member 132 includes a belt portion 132a and a head portion 132b. The belt portion 132a is a strip-shaped member for bundling multiple members together. The head portion 132b is a member for fixing both ends of the belt portion 132a. The belt portion 132a binds the covering member 130 and the return pipe 112a together, and is fixed by the head portion 132b. The head portion 132b is positioned on the covering member 130, but not on the return pipe 112a. In other words, the head portion 132b contacts the covering member 130 but not the return pipe 112a. This configuration prevents the return pipe 112a from being damaged by the head portion 132b.

[0032] Furthermore, the fixing position where the connection pipe 120 and the return pipe 112 are fixed is the position on the return pipe 112 farthest from the fins 100, i.e., the bottom part of the U-shape of the return pipe 112. This makes it possible to ensure the bending diameter when bending the connection pipe 120.

[0033] As described above, in the air conditioner 1 of this embodiment, the shortened portion 1201 of the connecting pipe 120 is shorter than in the past at the connection portion between the connecting pipe 120 and the heat transfer pipe 110. Therefore, refrigerant noise can be suppressed even when aluminum pipes are used as the heat transfer pipes of the indoor heat exchanger 6. Furthermore, because the connecting pipe 120 is fixed to the return pipe 112a, it is possible to prevent the connecting pipe 120 from breaking when it is bent during installation of the air conditioner 1.

[0034] It should be noted that the present invention is not limited to the specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims, such as applying a modified example of one embodiment to another embodiment.

[0035] In a first modified example, the connection pipe 120 only needs to be fixed to the return pipe 112, and the position and the number of fixing points are not limited to those described in the embodiment. The fixing point is preferably close to the connection portion between the heat transfer tube 110 and the connection pipe 120, but on the other hand, if there are restrictions due to the arrangement of other components, it does not have to be the closest return pipe 112. Furthermore, the connection pipe 120 may be fixed to multiple return pipes 112 at multiple points.

[0036] In a second modified example, the connecting pipe 120 may be fixed to a member other than the connecting pipe inside the indoor unit 2, and the fixing destination is not limited to the return pipe 112. For example, the connecting pipe 120 may be fixed to a housing inside the indoor unit 2.

[0037] As a third variant, the length L2 of the tube contraction section 1201 located at at least one of the two refrigerant inlets and outlets 114 of the indoor heat exchanger 6 may be shorter than the length of the tube contraction section (narrow diameter section) inserted into the refrigerant inlet and outlet of the outdoor heat exchanger 10.

[0038] As a fourth modification, it is only necessary that the length L2 of the tube contraction section 1201 is shorter than the length L1 of the secondary tube expansion section 1101 in at least one of the two refrigerant inlets and outlets 114 of the indoor heat exchanger 6 .

[0039] As a fifth variant, in at least one of the two refrigerant inlets and outlets 114 of the indoor heat exchanger 6, the length L3 of the portion 1203 of the contraction section 1201 that overlaps with the fin region 1001 may be shorter than the length of the portion that overlaps with the fins of the connecting pipe inserted into the refrigerant inlet and outlet of the outdoor heat exchanger.

[0040] REFERENCE SIGNS LIST 1 Air conditioner 2 Indoor unit 3 Outdoor unit 4 Remote control 5 Remote control communication unit 6 Indoor heat exchanger 7 Cross flow fan 8 Indoor fan motor 9 Compressor 10 Outdoor heat exchanger 11 Outdoor fan 11a Outdoor fan motor 12 Outdoor expansion valve 13 Four-way valve 14 Compressor motor 100 Fin 110 Heat transfer tube 112 Return pipe 112a Return pipe 114 Refrigerant inlet / outlet 120 Connecting pipe 120a Straight section 120b Part 121 End 130 Covering member 132 Fixing member 1001 Fin region 1101 Expanded section 1201 Contracted section 1202 Starting point 1203 Overlapping section

Claims

1. A heat exchanger comprising a heat transfer tube formed of aluminum or an aluminum alloy and provided in an indoor heat exchanger, and a connection pipe connected to the heat transfer tube and at least partially formed of aluminum or an aluminum alloy, wherein a reduced-diameter portion formed at an end of the connection pipe is inserted into the heat transfer tube, and at least one of the lengths of the reduced-diameter portions inserted into each of two refrigerant inlets and outlets of the indoor heat exchanger is shorter than the length of the reduced-diameter portion inserted into a refrigerant inlet and outlet of an outdoor heat exchanger.

2. A heat exchanger comprising a heat transfer tube formed of aluminum or an aluminum alloy and provided in an indoor heat exchanger, and a connection pipe connected to the heat transfer tube and at least partially formed of aluminum or an aluminum alloy, wherein the heat transfer tube has a large-diameter portion having an outer diameter larger than a portion overlapping a fin region of the indoor heat exchanger, a reduced-diameter portion formed at an end of the connection pipe is inserted into the heat transfer tube, and at least one of the lengths of the reduced-diameter portions inserted into each of two refrigerant inlets and outlets of the indoor heat exchanger is shorter than the length of the large-diameter portion.

3. A heat exchanger comprising a heat transfer tube formed of aluminum or an aluminum alloy and provided in an indoor heat exchanger, and a connection pipe inserted into the heat transfer tube and at least partially formed of aluminum or an aluminum alloy, wherein the connection pipe is inserted up to a portion overlapping a fin region of the indoor heat exchanger, and at least one of the lengths of the portions of the connection pipe inserted into each of two refrigerant inlets and outlets of the indoor heat exchanger and overlapping the fin region is shorter than the length of the portion of the connection pipe inserted into a refrigerant inlet and outlet of an outdoor heat exchanger and overlapping the fin region.

4. The heat exchanger according to any one of claims 1 to 3, wherein the connection pipe is connected to the heat transfer tube in one pass.

5. The heat exchanger according to any one of claims 1 to 3, wherein the connection pipe and the heat transfer tube are connected by a brazing material.

6. The heat exchanger according to any one of claims 1 to 3, wherein at least one of the connection pipes is fixed to another member other than the connection pipe.

7. The heat exchanger according to claim 6, wherein at least one of the connection pipes is fixed to a return pipe connecting the heat transfer tubes to each other.

8. The heat exchanger according to claim 1, wherein the reduced-diameter portion is inserted up to a portion overlapping a fin region of the indoor heat exchanger.

9. The air conditioner according to claim 2, wherein the small-diameter portion is inserted up to a portion overlapping the fin region in the indoor heat exchanger.