JP7741371B2 - Heat exchangers and air conditioners - Google Patents

Description

This disclosure relates to a heat exchanger and an air conditioner.

Patent Document 1 discloses a heat exchanger in which return bend pipes are joined to both ends of a straight pipe through which a refrigerant flows.

International Publication No. 2008/108336

In recent years, heat exchangers have been increasingly integrated by reducing the spacing between heat transfer tubes to which connecting tubes such as return bend pipes are connected. As heat exchangers become more integrated, narrow locations of heat transfer tube spacing may arise. Publicly known heat exchangers, including the heat exchanger disclosed in Patent Document 1, do not teach changing the shape of the connecting tubes depending on the spacing between the heat transfer tubes. The proposer of this disclosure came up with the idea that in order to increase the integration of heat exchangers, in addition to reducing the spacing between the heat transfer tubes, the shape of the connecting tubes should also be devised.

The object of this disclosure is to provide a highly integrated heat exchanger and an air conditioner equipped with the same.

The heat exchanger disclosed herein comprises a plurality of heat transfer tubes through which a refrigerant flows, a first connecting tube connecting the ends of the heat transfer tubes arranged at a first interval among the plurality of heat transfer tubes, and a second connecting tube connecting the ends of the heat transfer tubes arranged at a second interval smaller than the first interval among the plurality of heat transfer tubes, wherein the outer diameter of the second connecting tube is smaller than the outer diameter of the first connecting tube.

According to the present disclosure, the ends of the heat transfer tubes arranged at the second interval are connected by a second connecting tube with a smaller outer diameter, making it possible to manufacture a highly integrated heat exchanger.

In the above heat exchanger, the second connecting pipe may be made of aluminum or an aluminum alloy.

In the above heat exchanger, the multiple heat transfer tubes, the first connecting tube, and the second connecting tube may be made of aluminum or an aluminum alloy. This allows the heat exchanger to be made lighter.

The heat exchanger may have multiple rows, each row consisting of two or more of the heat transfer tubes, with the first connecting tube connecting the heat transfer tubes in the same row and the second connecting tube connecting the heat transfer tubes in adjacent rows. This allows for the use of second connecting tubes with a smaller outer diameter at locations spanning rows in a heat exchanger where the row pitch is smaller than the row pitch, thereby enabling the manufacture of a highly integrated heat exchanger.

In the above heat exchanger, the heat exchanger may have a first section and a second section, and the heat transfer tubes of the first section and the heat transfer tubes of the second section may be connected by the second connecting tube. This allows for high integration of a heat exchanger composed of multiple sections.

In the above heat exchanger, the heat transfer tubes in the first section and the heat transfer tubes in the second section that have the shortest distance between them may be connected by the second connecting tube. This allows for high integration of a heat exchanger in which each of the multiple sections has multiple rows.

In the above heat exchanger, the heat transfer tubes in the first section that are not connected to the second connecting tube may be connected to the heat transfer tubes in the second section that are not connected to the second connecting tube by the first connecting tube.

In the above heat exchanger, the inner diameter of the heat transfer tube to which the second connecting tube is connected may be equal to or greater than the inner diameter of the second connecting tube. This makes it possible to suppress an increase in pressure loss in the heat transfer tube to which the second connecting tube is connected.

In the above heat exchanger, the second spacing may be smaller than half the first spacing. Even when there are locations where the spacing between the heat transfer tubes is very small, a highly integrated heat exchanger can be manufactured.

In another aspect, the present disclosure relates to an air conditioner including an indoor unit equipped with the above-described heat exchanger.

FIG. 2 is a side view of the heat exchanger according to the first embodiment of the present disclosure. FIG. 10 is an external view of an air conditioner including a heat exchanger according to a second embodiment of the present disclosure. FIG. 3 is a schematic configuration diagram of the air conditioner shown in FIG. 2. FIG. 3 is a cross-sectional view of the indoor unit shown in FIG. 2 . FIG. 5 is a side view of the heat exchanger shown in FIG. 4 . 5 is a diagram showing a state in which two heat transfer tubes arranged at a first interval in the heat exchanger shown in FIG. 4 are connected by a U-bend. FIG. 5 is a diagram showing a state in which two heat transfer tubes arranged at a second interval in the heat exchanger shown in FIG. 4 are connected by a U-bend. FIG.

First Embodiment
A heat exchanger according to a first embodiment of the present disclosure will now be described with reference to FIG. 1 . The heat exchanger 1 shown in FIG. 1 is a cross-fin tube heat exchanger panel including a plurality of heat transfer tubes 2, a plurality of U-bends 3, and a plurality of fins 4. In the heat exchanger 1, the plurality of heat transfer tubes 2 are arranged in two rows. Each heat transfer tube 2 is a straight tube made of aluminum or an aluminum alloy and extends in a direction perpendicular to the plane of FIG. 1 . While the present embodiment describes a case in which the heat transfer tubes 2 are straight tubes, the heat transfer tubes 2 may also be hairpin tubes including two straight tube sections and a U-shaped section connecting them. The plurality of heat transfer tubes 2 all have the same outer and inner diameters. Each U-bend 3 is made of aluminum or an aluminum alloy and is a connecting tube that connects the ends of the heat transfer tubes 2. In the present embodiment, the up-down direction and the front-rear direction of the heat exchanger 1 are defined as shown in FIG. 1 .

Multiple heat transfer tubes 2 penetrate each fin 4, which is a flat plate member. Each fin 4 is in contact with the outer surfaces of multiple heat transfer tubes 2. Each fin 4 is made of aluminum or an aluminum alloy. The heat exchanger 1 according to this embodiment is used, for example, as an indoor heat exchanger for an air conditioner. In this case, heat is exchanged between the refrigerant supplied from the outdoor unit and flowing through the heat transfer tubes 2 and the air that comes into contact with the heat transfer tubes 2 and fins 4.

In the heat exchanger 1 shown in FIG. 1 , horizontally extending heat transfer tubes are arranged at equal intervals vertically to form a front row and a rear row. The front row is located upstream of the airflow passing through the heat exchanger 1, and the rear row is located downstream of the airflow passing through the heat exchanger 1. The pitch (row pitch) P1 (first interval) between the heat transfer tubes 2 in each row is the same for the front row and the rear row. The pitch (row pitch) P2, which is the horizontal interval between the front row and the rear row, is smaller than the row pitch P1 (P2<P1). The top heat transfer tube 2 in the front row is located half the row pitch P1 lower than the top heat transfer tube 2 in the rear row. Therefore, the interval P3 (second interval) between the top heat transfer tube 2 in the front row and the top heat transfer tube 2 in the rear row is the square root of ((½)P1) ² + P2 ² , which is smaller than the row pitch P1 (P3<P1). In this embodiment, the interval P3 is smaller than 1/2 of the step pitch P1 (P3<(1/2)P1).

U-bends 3 are brazed to both ends of the heat transfer tubes 2 in each row, except for one end of the lowest heat transfer tube 2 to which the refrigerant piping is connected. In this embodiment, there are two types of U-bends 3: U-bends 3a and U-bends 3b, which have different outer diameters. The outer diameter φB of U-bend 3b is smaller than the outer diameter φA of U-bend 3a (φB < φA). In addition to the two U-bends 3a depicted in FIG. 1, the heat transfer tubes 2 in the same row are connected by three U-bends 3a connecting the opposite ends of the heat transfer tubes 2 (not depicted in FIG. 1). The ends of the heat transfer tubes 2 at the top of two adjacent rows, the front row and the rear row, are connected by U-bends 3b. As a result, in the heat exchanger 1, a refrigerant flow path is formed that runs from one end of the heat transfer tube 2 at the bottom of the front row (to which the U-bend 3 is not connected), through the heat transfer tubes 2 in the front and rear rows, five U-bends 3a, and one U-bend 3b, to one end of the heat transfer tube 2 at the bottom of the rear row (to which the U-bend 3 is not connected).

Although not shown, the ends of the heat transfer tubes 2 and the ends of the U-bends 3b are flared (expanded). The inner circumferential surface near the end of each heat transfer tube 2 and the outer circumferential surface near the ends of the U-bends 3a and 3b are joined by brazing. In this embodiment, the inner diameter of the heat transfer tube 2 is the same as the inner diameter of the U-bend 3a and larger than the inner diameter of the U-bend 3b. The inner diameters of the U-bends 3a and 3b are values in the portions other than the expanded diameter portions. In a variation, the inner diameter of the heat transfer tube 2 may be larger or smaller than the inner diameter of the U-bend 3a, or may be the same as or smaller than the inner diameter of the U-bend 3b. In another variation, the area near the end of the U-bend 3b may not be flared.

As described above, in this embodiment, the outer diameter of the U-bends 3b connecting the ends of the heat transfer tubes 2 arranged at intervals P3 in the heat exchanger 1 is smaller than the outer diameter of the U-bends 3a connecting the ends of the heat transfer tubes 2 arranged at intervals P1. This allows for a high level of integration of the heat exchanger 1. In this embodiment, a highly integrated heat exchanger can be manufactured by using U-bends 3b with small outer diameters at locations spanning rows in a heat exchanger where the row pitch is smaller than the row pitch. Because the interval P3 is smaller than half the row pitch P1, even higher integration can be achieved. In the highly integrated heat exchanger 1 according to this embodiment, there are significant benefits to using the U-bends 3b made of aluminum or an aluminum alloy. Furthermore, because the heat transfer tubes 2 and U-bends 3a, 3b are made of aluminum or an aluminum alloy, the weight of the heat exchanger 1 can be reduced.

In this embodiment, the inner diameter of the heat transfer tube 2 to which the U-bend 3b is connected is larger than the inner diameter of the U-bend 3b. This makes it possible to suppress an increase in pressure loss in the heat transfer tube 2 to which the U-bend 3b, which has a small outer diameter, is connected.

Second Embodiment
An air conditioner including a heat exchanger according to a second embodiment of the present disclosure will now be described. The air conditioner 10 shown in Fig. 2 includes an indoor unit 12 that is attached to a wall or the like inside a room, and an outdoor unit 13 that is installed outdoors. The indoor unit 12 and the outdoor unit 13 are connected via refrigerant piping 17 to form a refrigerant circuit.

As shown in FIG. 3 , the outdoor unit 13 includes a compressor 21, a four-way switching valve 22 connected to the discharge side of the compressor 21, an accumulator 23 connected to the suction side of the compressor 21, an outdoor heat exchanger 24 connected to the four-way switching valve 22, and an electronic expansion valve 25 connected to the outdoor heat exchanger 24. The outdoor heat exchanger 24 is a cross-fin tube heat exchanger panel including an outdoor piping section and multiple fins 24c. The outdoor piping section is composed of multiple heat transfer tubes 24a and a U-bend 24b, which is a connecting tube connecting the ends of the heat transfer tubes 24a. While the present embodiment describes a case where the heat transfer tubes 24a are straight tubes, the heat transfer tubes 24a may also be hairpin tubes including two straight tube sections and a U-shaped portion connecting them. Multiple heat transfer tubes 24a penetrate each fin 24c, which is a flat plate member. Each fin 24c is in contact with the outer circumferential surface of each of the heat transfer tubes 24a. Each of the heat transfer tubes 24a, the U-bends 24b, and each of the fins 24c are made of aluminum or an aluminum alloy.

The electronic expansion valve 25 is connected to the connecting pipe 32 via the filter 26 and the liquid shut-off valve 27, and is connected to one end of the indoor heat exchanger 41 via the connecting pipe 32. The four-way switching valve 22 is connected to the connecting pipe 31 via the gas shut-off valve 28, and is connected to the other end of the indoor heat exchanger 41 via the connecting pipe 31. These connecting pipes 31 and 32 correspond to the refrigerant pipe 7 in Figure 2. The outdoor unit 13 is also provided with an outdoor fan 29 to discharge air that has undergone heat exchange in the outdoor heat exchanger 24 to the outside. The outdoor fan 29 is a propeller fan driven by an outdoor fan motor 30. In the outdoor heat exchanger 24, heat exchange occurs between the refrigerant flowing through the heat transfer tube 24a via the compressor 21 or the electronic expansion valve 25 and the air that comes into contact with the heat transfer tube 24a and fins 24c.

The indoor unit 12 is provided with an indoor heat exchanger 41 connected to the connecting pipes 31 and 32. The indoor heat exchanger 41 is a cross-fin tube type heat exchanger panel including an indoor piping section and multiple fins 41c. The indoor piping section is composed of multiple heat transfer tubes 41a and U-bends 41b, which are connecting pipes connecting the ends of the heat transfer tubes 41a. While this embodiment describes a case where the heat transfer tubes 41a are straight tubes, the heat transfer tubes 41a may also be hairpin tubes including two straight tube sections and a U-shaped section connecting them. Multiple heat transfer tubes 41a penetrate each fin 41c, which is a flat plate member. Each fin 41c is in contact with the outer surfaces of the multiple heat transfer tubes 41a. Each heat transfer tube 41a and each fin 41c is made of aluminum or an aluminum alloy. In the indoor heat exchanger 41, heat is exchanged between the refrigerant supplied from the outdoor unit 13 via the refrigerant piping 7 and flowing through the heat transfer tubes 41a, and the air that comes into contact with the heat transfer tubes 41a and fins 41c.

The indoor unit 12 contains an indoor fan 42 and an indoor fan motor 43 that drives the indoor fan 42 to rotate. The indoor fan 42 is a cylindrical crossflow fan with numerous blades on its circumferential surface, and generates an airflow in a direction intersecting its rotation axis. The indoor fan 42 draws indoor air into the indoor unit 12 through the main suction port 46a and the sub-suction port 46b, and blows the air into the room from the air outlet 49 after heat exchange with the refrigerant flowing inside the heat transfer tube 41a of the indoor heat exchanger 41.

In this embodiment, the indoor heat exchanger 41 can be divided into four sections shown in FIG. 4: an upper front section Ba, a middle front section Bb, a lower front section Bc, and a rear section Bd. These four sections Ba, Bb, Bc, and Bd are connected to each other by connecting pipes through which the refrigerant passes, as described below. The upper end of the upper front section Ba and the upper end of the rear section Bd of the indoor heat exchanger 41 are close to each other, with the upper front section Ba positioned more forward as it lowers and the rear section Bd positioned more rearward as it lowers, forming an inverted V shape in side view. The middle front section Bb extends vertically, and the lower front section Bc is inclined so that it is positioned more rearward as it lowers. In this embodiment, each fin 41c is composed of four regions corresponding to the upper front section Ba, middle front section Bb, lower front section Bc, and rear section Bd. These four regions are spaced apart from one another between the upper front surface Ba and the rear surface Bd, between the upper front surface Ba and the middle front surface Bb, and between the middle front surface Bb and the lower front surface Bc. In this manner, each fin 41c is separated into four regions. In this embodiment, the up-down and front-rear directions of the indoor unit 12 are defined as shown in Figure 4.

The indoor heat exchanger 41 will be described in detail with further reference to Fig. 5. As shown in Fig. 5, in each of the four sections Ba, Bb, Bc, and Bd, a plurality of straight pipes relating to a plurality of heat transfer pipes 41a are arranged in two rows and multiple stages. Each row is formed by a plurality of straight pipes on the upstream and downstream sides of the airflow toward the indoor fan 42 .

In the upper front portion Ba, horizontally extending heat transfer tubes 41a are arranged diagonally at equal intervals so that they are positioned lower toward the front, forming a front row and a rear row. In the rear portion Bd, horizontally extending heat transfer tubes 41a are arranged diagonally at equal intervals so that they are positioned higher toward the front, forming a front row and a rear row. In the middle front portion Bb, horizontally extending heat transfer tubes 41a are arranged diagonally at equal intervals up and down, forming a front row and a rear row. In the lower front portion Bc, horizontally extending heat transfer tubes 41a are arranged diagonally at equal intervals so that they are positioned higher toward the front, forming a front row and a rear row. In each of the four portions Ba, Bb, Bc, and Bd, the front row is located upstream of the air passing through the heat exchanger 41, and the rear row is located downstream of the air passing through the heat exchanger 41.

The pitch (row pitch) P11 (first interval), which is the spacing between the heat transfer tubes 41a in each row, is the same for all four sections Ba, Bb, Bc, and Bd, both in the front and rear rows. The pitch (row pitch) P12, which is the spacing between the front and rear rows, is the same for all four sections Ba, Bb, Bc, and Bd, and is smaller than the row pitch P11 (P12 < P11). In each of the sections Ba, Bb, Bc, and Bd, the heat transfer tube 41a at one end of the front row is shifted by half the row pitch P11 from the heat transfer tube 41a at one end of the rear row. As an example, the row pitch P11 is 19 mm, and the row pitch P12 is 11 mm.

In this embodiment, one end of the heat transfer tube 41a at the bottom of the front row in the upper front section Ba is connected to the connecting pipe 31. Furthermore, one end of the heat transfer tube 41a at the top of the rear row in the intermediate front section Bb is connected to the connecting pipe 32. In all sections Ba, Bb, Bc, and Bd, U-bends 41b are brazed to both ends of each heat transfer tube 2 in the same row, except for one end of the heat transfer tube 41a connected to the connecting pipes 31 and 32. In this embodiment, there are two types of U-bends 41b: U-bends 51a and U-bends 51b, which have different outer diameters. The outer diameter φD1 of the U-bend 51b is smaller than the outer diameter φC1 of the U-bend 51a (φD1<φC1). There are also two types of U-bends 51a: U-bends 51a1 and U-bends 51a2, which have different inner bending radii. The inner bend radius R1 (see FIG. 6A) of U-bend 51a1 is smaller than the inner bend radius of U-bend 51a2. As an example, the outer diameter φC1 is 7 mm, the outer diameter φD1 is 6 mm, and the wall thickness of U-bends 51a and 51b is 1.0 mm.

The heat transfer tubes 41a in the same row in the upper front face Ba are connected by two U-bends 51a1 shown in FIG. 5 as well as three U-bends 51a1 connecting the opposite ends of the heat transfer tubes 41a (not shown in FIG. 5). Similarly, in the other sections Bb, Bc, and Bd, the ends of the heat transfer tubes 41a in the same row are each connected by a U-bend 51a1. Furthermore, one end of the heat transfer tube 41a at the bottom of the front row in the intermediate front face Bb is connected by a U-bend 51a1 to one end of the heat transfer tube 41a at the top of the front row in the lower front face Bc. One end of the heat transfer tube 41a at the bottom of the rear row in the intermediate front face Bb is connected by a U-bend 51a1 to one end of the heat transfer tube 41a at the top of the rear row in the lower front face Bc. One end of the heat transfer tube 41a at the top of the front row on the upper front surface Ba is connected to one end of the heat transfer tube 41a at the top of the front row on the back surface Bd by a U-bend 51a2. The spacing P13 between the two heat transfer tubes 41a connected by the U-bend 51a2 is greater than the row pitch P11 (P13 > P11). As an example, the spacing P13 is 14 mm.

One end of the heat transfer tube 41a at the bottom of the front row on the lower front surface Bc is connected by a U-bend 51b to one end of the heat transfer tube 41a at the bottom of the rear row on the lower front surface Bc. One end of the heat transfer tube 41a at the bottom of the front row on the rear surface Bd is connected by a U-bend 51b to one end of the heat transfer tube 41a at the bottom of the rear row on the rear surface Bd. The spacing P14 between two heat transfer tubes 41a connected by U-bends 51b at the two locations in two adjacent rows within the same section is equal to the square root of ((1/2)P11) ² + ^P122 , which is smaller than the row pitch P11 (P14 < P11). As described above, in this embodiment, U-bends 51b with small outer diameters are used at locations spanning the rows on both the lower front surface Bc and the rear surface Bd.

One end of the heat transfer tube 41a at the top of the front row in the front intermediate section Bb is connected by a U-bend 51b to one end of the heat transfer tube 41a at the bottom of the rear row in the front upper section Ba. The heat transfer tube 41a at the top of the rear row in the front upper section Ba is connected by a U-bend 51b to the heat transfer tube 41a at the top of the rear row in the rear section Bd. The spacing P15 between the two heat transfer tubes 41a connected by U-bends 51b at the two locations in the two adjacent rows in the adjacent sections is smaller than the row pitch P11 (P15 < P11). In this embodiment, spacing P15 is the same as spacing P14. As such, in this embodiment, U-bends 51b with small outer diameters are used at the locations spanning the front upper section Ba and front intermediate section Bb, and at the locations spanning the front upper section Ba and rear section Bd. The U-bend 51b connects the two heat transfer tubes 41a with the shortest distance between the multiple heat transfer tubes 41a in the upper front surface Ba and the multiple heat transfer tubes 41a in the intermediate front surface Bb. The U-bend 51b also connects the two heat transfer tubes 41a with the shortest distance between the multiple heat transfer tubes 41a in the upper front surface Ba and the multiple heat transfer tubes 41a in the rear surface Bd.

The above-mentioned U-bend 51a2 connects the heat transfer tubes 41a in the upper front portion Ba to which the U-bend 51b is not connected, and the heat transfer tubes 41a in the rear portion Bd to which the U-bend 51b is not connected.

By connecting the heat transfer tubes 41a to each other with U-bends 41b (51a1, 51a2, 51b) as described above, a refrigerant flow path is formed in the heat exchanger 41, extending from one end of the heat transfer tube 41a connected to the connecting pipe 31, via the multiple heat transfer tubes 41a of the four sections Ba, Bb, Bc, and Bd and the multiple U-bends 51a1, 51a2, and 51b, to one end of the heat transfer tube 41a connected to the connecting pipe 32.

The connection points between the heat transfer tube 41a and the U-bends 51a1 and 51b will be described in detail with reference to Figures 6A and 6B. The connection between the U-bend 51a2 and the heat transfer tube 41a is the same as that described in relation to Figure 6A, except for the inner bend radius, so its description will be omitted.

The U-bends 51a1 connecting the ends of the heat transfer tubes 41a arranged at a step pitch of P11 have an outer diameter φC1 and an inner bending radius R1 as described above. The U-bends 51b connecting the ends of the heat transfer tubes 41a arranged at P14 have an outer diameter φD1 smaller than the outer diameter φC1 and an inner bending radius R2 (R2 < R1). The wall thickness of the U-bends 51a1 is the same as the wall thickness of the U-bends 51b. The U-bends 51a1 and 51b may be obtained by bending a straight pipe.

As shown in FIG. 6A, the U-bend 51a is not flared near its end, but the heat transfer tube 41a connected to the U-bend 51a is flared near its end to form an expanded diameter section 52. The inner diameter φE1 of the expanded diameter section 52 is slightly larger than the outer diameter φC1 of the U-bend 51a and the outer diameter φE2 of the heat transfer tube 41a (values at the portion other than the expanded diameter section 52). The U-bend 51a is inserted near its end into the expanded diameter section 52 of the heat transfer tube 41a. The outer peripheral surface of the U-bend 51a near its end and the inner peripheral surface of the expanded diameter section 52 of the heat transfer tube 41a are joined by brazing. Meanwhile, as shown in FIG. 6B, the U-bend 51b is flared near its end to form an expanded diameter section 53. The heat transfer tube 41a connected to the U-bend 51b is also flared near its end to form an expanded diameter section 54. The inner diameter φE3 of the expanded diameter portion 53 is slightly smaller than the outer diameter φE2 of the heat transfer tube 41a. The inner diameter of the expanded diameter portion 54 is slightly larger than the outer diameter of the expanded diameter portion 53. The expanded diameter portion 53 of the U-bend 51b is inserted into the expanded diameter portion 54 of the heat transfer tube 41a1. The outer peripheral surface of the expanded diameter portion 53 of the U-bend 51b and the inner peripheral surface of the expanded diameter portion 54 of the heat transfer tube 41a1 are joined by brazing.

In this embodiment, the inner diameter φE4 of the heat transfer tube 41a is the same as the inner diameter φC2 of the U bend 51a1, and the inner diameter φC2 of the U bend 51a1 is larger than the inner diameter φD2 of the U bend 51b. Therefore, the inner diameter φE4 of the heat transfer tube 41a is larger than the inner diameter φD2 of the U bend 51b (φE4 > φD2). The inner diameter φE4 of the heat transfer tube 41a is a value other than the expanded diameter portions 52 and 53, and the inner diameter φD2 of the U bend 51b is a value other than the expanded diameter portion 53. Alternatively, the inner diameter φE4 of the heat transfer tube 41a may be larger or smaller than the inner diameter φC2 of the U bend 51a1, or may be the same as or smaller than the inner diameter φD2 of the U bend 51b. The U bend 51b does not need to be flared near its end.

As such, in this embodiment, the outer diameter φD1 of the U-bends 51b connecting the ends of the heat transfer tubes 41a arranged at intervals P14 in the heat exchanger 41 is smaller than the outer diameter φC1 of the U-bends 51a1 connecting the ends of the heat transfer tubes 2 arranged at intervals P11. This allows for a high level of integration of the heat exchanger 41. In particular, in this embodiment, in a heat exchanger where the row pitch is smaller than the stage pitch, U-bends 51b with small outer diameters are used in locations spanning rows within the lower front face Bc and the rear face Bd, in locations spanning the upper front face Ba and the intermediate front face Bb, and in locations spanning the upper front face Ba and the rear face Bd, allowing for the manufacture of a highly integrated heat exchanger.

In addition, a U-bend 51b is used at the point spanning the upper front surface Ba and the rear surface Bd, connecting the two heat transfer tubes 41a (spaced apart by P15) that are the shortest distance between these two heat transfer tubes 41a, and a U-bend 51a2 is used, connecting two heat transfer tubes 41a that are spaced apart by P13, which is greater than the row pitch P11. This results in a highly integrated heat exchanger 41 that connects the upper front surface Ba and the rear surface Bd, each of which is made up of multiple heat transfer tubes 41a arranged in two rows and multiple rows.

In addition, in the highly integrated heat exchanger 41 according to this embodiment, there is a significant benefit to making the U-bend 51b out of aluminum or an aluminum alloy. Furthermore, because the heat transfer tube 41a and the U-bends 51a and 51b are made of aluminum or an aluminum alloy, the weight of the heat exchanger 41 can be reduced.

Furthermore, in this embodiment, the inner diameter φE4 of the heat transfer tube 2 to which the U bend 51b is connected is larger than the inner diameter φD2 of the U bend 51b. Therefore, it is possible to suppress an increase in pressure loss in the heat transfer tube 2 to which the U bend 51b, which has a small outer diameter φD1 and inner diameter φD2, is connected.

<Modification>
In the above-described embodiment, a U-bend is used as the connecting pipe connecting the ends of the heat transfer tubes, but a connecting pipe other than a U-bend may be used. Furthermore, in the above-described embodiment, the heat transfer tubes are arranged in two rows, but the heat transfer tubes may be arranged in one row, three or more rows, or may not form a row. Furthermore, the heat transfer tubes may not be straight but may be bent. The heat transfer tubes and/or the U-bend may be made of copper or a copper alloy.

In the second embodiment, the outer diameter of U-bend 51a2 does not have to be the same as the outer diameter φC1 of U-bend 51a1, as long as it is larger than the outer diameter φD1 of U-bend 51b. Furthermore, spacing P14 and spacing P15 may be different. Furthermore, the outer diameter of the U-bend connecting two heat transfer tubes 41a spaced apart by spacing P14 may be different from the outer diameter of the U-bend connecting two heat transfer tubes 41a spaced apart by spacing P15. In the above-described embodiment, the outer peripheral surface near the end of each heat transfer tube and the inner peripheral surface near the end of the U-bend are joined by brazing, but the inner peripheral surface near the end of the U-bend and the outer peripheral surface near the end of each heat transfer tube may also be joined.

In the second embodiment described above, the wall thickness of U-bend 51a is the same as the wall thickness of U-bend 51b, and the outer diameter of U-bend 51a is larger than the outer diameter of U-bend 51b. However, the outer diameters of U-bend 51a and U-bend 51b may be the same, and the wall thickness of U-bend 51b may be larger than the wall thickness of U-bend 51a. This allows for the manufacture of a highly integrated heat exchanger without causing bending wrinkles in the U-bend.

The technology disclosed in the second embodiment described above can also be applied to outdoor heat exchangers. The indoor unit is not limited to the wall-mounted type shown in Figure 2, but may also be a ceiling-mounted type, a ceiling-suspended type, or the like. The wall-mounted indoor unit shown in Figure 2 has size restrictions, so there are great benefits to adopting the heat exchanger disclosed herein. Furthermore, the heat exchanger disclosed herein can be used for applications other than air conditioners.

Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims.

1 Heat exchanger 2 Heat transfer tube 3 (3a, 3b) U-bend (connecting tube)
4 Fin 10 Air conditioner 12 Indoor unit 13 Outdoor unit 17 Refrigerant piping 24 Outdoor heat exchanger 24a Heat transfer tube 24b U-bend 24c Fin 41 Indoor heat exchanger (front upper part Ba, front middle part Bb, front lower part Bc, rear part Bd)
41a Heat transfer tube 41b (51a1, 51a2, 51b) U-bend (connecting tube)
41c fins

Claims (8)

a plurality of heat transfer tubes through which a refrigerant flows;
a first connecting pipe connecting ends of the heat transfer tubes arranged at a first interval among the plurality of heat transfer tubes;
a second connecting pipe connecting ends of the heat transfer tubes arranged at second intervals that are smaller than the first intervals among the plurality of heat transfer tubes,
The outer diameter of the second connecting pipe is smaller than the outer diameter of the first connecting pipe,
a heat exchanger in which inner diameters of one and the other of the plurality of heat transfer tubes to which the second connecting tube is connected are larger than an inner diameter of the second connecting tube,
the heat exchanger has a plurality of rows, each row consisting of two or more of the heat transfer tubes;
the first connecting pipe connects the heat transfer tubes in the same row;
The second connecting pipe connects the heat transfer tubes in adjacent rows . The heat exchanger according to claim 1, wherein the second connecting pipe is made of aluminum or an aluminum alloy. The heat exchanger according to claim 1, wherein the plurality of heat transfer tubes, the first connecting tube, and the second connecting tube are made of aluminum or an aluminum alloy. the heat exchanger having a first portion and a second portion;
4. The heat exchanger according to claim 1, wherein the heat transfer tubes of the first portion and the heat transfer tubes of the second portion are connected by the second connecting tubes. The heat exchanger according to claim 4 , wherein the heat transfer tubes in the first portion and the heat transfer tubes in the second portion that have the shortest distance between them are connected by the second connecting pipe. 6. The heat exchanger according to claim 5, wherein the heat transfer tubes in the first portion that are not connected to the second connecting tube and the heat transfer tubes in the second portion that are not connected to the second connecting tube are connected by the first connecting tube. The heat exchanger according to any one of claims 1 to 6 , wherein the second interval is smaller than half of the first interval. An air conditioner including an indoor unit equipped with the heat exchanger according to any one of claims 1 to 7 .