HEAT EXCHANGER

Abstract

A heat exchanger includes a plurality of fins, and a plurality of flat tubes to perform heat exchange of air passing in a first direction between the tubes and fins. Each fin includes a plurality of through hole portions through which the flat tubes pass, a connecting portion that extends in a second direction intersecting the first direction without being passed through by the tubes, and at least one fin pitch defining portion in contact with an adjacent fin. In each fin, one fin pitch defining portion is provided for every N flat tubes. N is an integer of at least two. The fin pitch defining portion of each fin includes at least two raised portions formed by cutting and raising, in at least two directions, a heat transfer portion of each fin. The heat transfer portion is located at a position other than the connecting portion.

Description

BACKGROUND

Technical Field

The present disclosure relates to a heat exchanger including a plurality of fins and a plurality of flat tubes.

Background Information

A heat exchanger including a plurality of flat tubes and a plurality of fins is used in an outdoor unit, or the like, of an air conditioner. Japanese Unexamined Patent Application Publication No. 2012-163318 discloses an example in which an outdoor heat exchanger used in an outdoor unit of an air conditioner includes flat tubes and fins.

SUMMARY

A heat exchanger according to a first aspect is a heat exchanger that includes a plurality of fins and a plurality of flat tubes, and performs heat exchange of air passing in a first direction between the plurality of flat tubes and the plurality of fins. Each of the fins includes a plurality of through hole portions, a connecting portion, and a heat transfer portion having one or more fin pitch defining portions. The plurality of flat tubes pass through the plurality of through hole portions. The connecting portion extends in a second direction intersecting the first direction without being passed through by the plurality of flat tubes. The one or more fin pitch defining portions are in contact with an adjacent fin and define a fin pitch. In each of the fins, one fin pitch defining portion is provided for every N (N being an integer of two or more) flat tubes. The fin pitch defining portion of each of the fins includes two or more raised portions formed by cutting and raising, in two or more directions, the heat transfer portion of each of the fins, the heat transfer portion being located at a position other than the connecting portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram illustrating an outline of a configuration of an air conditioner.

FIG. 2 is a view illustrating the appearance of an indoor unit and an outdoor unit of the air conditioner.

FIG. 3 is a plan view of an indoor heat exchanger inside the indoor unit.

FIG. 4 is a cross-sectional view of the indoor unit taken along line I-I in FIG. 3.

FIG. 5 is a perspective view of a first heat exchange section of an indoor heat exchange section.

FIG. 6 is a partially enlarged cross-sectional view illustrating a cross section of the first heat exchange section in FIG. 5 taken along plane B.

FIG. 7 is a plan view of the first heat exchange section as viewed in a thickness direction of a flat tube.

FIG. 8 is a partially enlarged plan view illustrating a portion of a fin.

FIG. 9 is a partially enlarged perspective view illustrating a portion of the fin, where a fin pitch defining portion is not formed.

FIG. 10 is a partially enlarged perspective view illustrating a portion of the fin, where the fin pitch defining portion is formed.

FIG. 11 is a graph illustrating air-side heat transfer coefficients for a plurality of types of fins.

FIG. 12 is a partially enlarged plan view illustrating an example of a fin configuration corresponding to the graph in FIG. 11.

FIG. 13 is a partially enlarged plan view illustrating another example of the fin configuration corresponding to the graph in FIG. 11.

FIG. 14 is a partially enlarged plan view illustrating another example of the fin configuration corresponding to the graph in FIG. 11.

FIG. 15 is a partially enlarged plan view illustrating another example of the fin configuration corresponding to the graph in FIG. 11.

FIG. 16 is a cross-sectional view illustrating another example of the indoor unit.

FIG. 17 is a cross-sectional view illustrating another example of the indoor unit.

FIG. 18 is a cross-sectional view illustrating another example of the indoor unit.

FIG. 19 is a partially enlarged plan view illustrating a fin configuration according to a modification B.

DETAILED DESCRIPTION OF EMBODIMENT(S)

(1) Overall Configuration

As illustrated in FIG. 1, a heat exchanger according to an embodiment is, for example, an indoor heat exchanger 1 applied to an indoor unit 110 of an air conditioner 100. The air conditioner 100 includes the indoor unit 110 and an outdoor unit 120. The indoor unit 110 is connected to the outdoor unit 120 via connection pipes 131 and 132.

As illustrated in FIG. 2, the indoor unit 110 includes a casing 111 and an indoor fan 112 in addition to the indoor heat exchanger 1. The indoor unit 110 is a wall-hung type unit that is hung and mounted on a wall WL in a room RM. The indoor unit 110 has a substantially rectangular parallelepiped appearance. The casing 111 mainly constitutes an outer surface of the indoor unit 110. The casing 111 houses the indoor heat exchanger 1 and the indoor fan 112 therein. The casing 111 has an inlet 113 and an outlet 114. Indoor air flows into the casing 111 through the inlet 113. Air heat exchanged with a refrigerant in the indoor heat exchanger 1 is blown out through the outlet 114. The posture (rotational angle) of a flap 115 is controlled. By changing the posture of the flap 115, the opening degree of the outlet 114 and the airflow direction in which the air blown out from the outlet 114 are adjusted.

The outdoor unit 120 is installed outside the room RM (outdoors), such as on the roof of a building or near the outer wall surface of the building, for example. The outdoor unit 120 includes a compressor 122, a four-way valve 123, an outdoor heat exchanger 124, an expansion valve 125, and an outdoor fan 126.

The compressor 122 sucks a low-pressure refrigerant from a suction port, compresses the refrigerant until the pressure of the refrigerant becomes high, and thereafter, discharges the refrigerant from a discharge port. The compressor 122 is, for example, a displacement compressor capable of varying capacity by changing the rotational speed of a built-in motor. The four-way valve 123 has a first port P1, a second port P2, a third port P3, and a fourth port P4.

The four-way valve 123 switches the flow direction of the refrigerant by switching between a first state (a state indicated by a broken line in FIG. 2) and a second state (a state indicated by a solid line in FIG. 2). In the first state, the first port P1 and the fourth port P4 communicate with each other, and the second port P2 and the third port P3 communicate with each other. In the second state, the first port P1 and the second port P2 communicate with each other, and the third port P3 and the fourth port P4 communicate with each other. The first port P1 is connected to the discharge port of the compressor 122. The second port P2 is connected to a gas-side inlet/outlet of the outdoor heat exchanger 124. The third port P3 is connected to the suction port of the compressor 122. The fourth port P4 is connected to the connection pipe 132.

The outdoor heat exchanger 124 is a heat exchanger that performs heat exchange between the refrigerant and outdoor air. A liquid-side inlet/outlet of the outdoor heat exchanger 124 is connected to the expansion valve 125. The gas-side inlet/outlet of the outdoor heat exchanger 124 is connected to the second port P2 of the four-way valve 123.

The expansion valve 125 decompresses the refrigerant. The expansion valve 125 is provided between the connection pipe 131 and the liquid side of the outdoor heat exchanger 124. The expansion valve 125 is, for example, an electric expansion valve whose opening degree is controllable.

The compressor 122, the four-way valve 123, the outdoor heat exchanger 124, the expansion valve 125, and the indoor heat exchanger 1 form a refrigerant circuit 200. In the refrigerant circuit 200, the refrigerant circulates through the compressor 122, the four-way valve 123, the outdoor heat exchanger 124, the expansion valve 125, and the indoor heat exchanger 1, thereby implementing a vapor compression refrigeration cycle. The air conditioning by the air conditioner 100 is performed by the implementation of the vapor compression refrigeration cycle. When the four-way valve 123 is switched to the first state (the state indicated by the broken line), a heating operation is performed. In this operation, the refrigerant circulates through the compressor 122, the indoor heat exchanger 1, the expansion valve 125, and the outdoor heat exchanger 124, returning to the compressor 122. When the four-way valve 123 is switched to the second state (the state indicated by the solid line), a cooling operation is performed. In this operation, the refrigerant circulates through the compressor 122, the outdoor heat exchanger 124, the expansion valve 125, and the indoor heat exchanger 1, returning to the compressor 122.

The indoor fan 112 generates an airflow of indoor air passing through the indoor heat exchanger 1. The passing of the indoor air through the indoor heat exchanger 1 facilitates heat exchange between the refrigerant passing through the indoor heat exchanger 1 and the indoor air. The indoor fan 112 can vary the volume of air passing through the indoor heat exchanger 1 by changing the rotational speed of a built-in motor.

The outdoor fan 126 generates an airflow of outdoor air passing through the outdoor heat exchanger 124. By sending outdoor air to the outdoor heat exchanger 124, the outdoor fan 126 facilitates heat exchange between the refrigerant passing through the outdoor heat exchanger 124 and the outdoor air. The outdoor fan 126 can vary the volume of air passing through the outdoor heat exchanger 124 by changing the rotational speed of a built-in motor.

(1-1) Heating Operation

When the indoor unit 110 receives a signal for an execution instruction of a heating operation, for example, from a remote controller 150, the air conditioner 100 starts the heating operation. During the heating operation, the air conditioner 100 switches the four-way valve 123 to the first state. The air conditioner 100 adjusts the rotational speed of the compressor 122, the opening degree of the expansion valve 125, and the rotational speed of the outdoor fan 126 to match the room temperature with a set temperature received, for example, from the remote controller 150. Additionally, the air conditioner 100 adjusts the rotational speed of the indoor fan 112 to achieve a set volume of air received, for example, from the remote controller 150. In the heating operation, the outdoor heat exchanger 124 functions as an evaporator for the refrigerant, and the indoor heat exchanger 1 functions as a radiator for the refrigerant.

During the heating operation, in the refrigerant circuit 200, a high-temperature, high-pressure refrigerant discharged from the compressor 122 releases heat by exchanging heat with the indoor air sent by the indoor fan 112 in the indoor heat exchanger 1. The indoor air heated in the indoor heat exchanger 1 is blown back into the room as conditioned air. The refrigerant that has released heat in the indoor heat exchanger 1 passes through the expansion valve 125 and is decompressed. The refrigerant expanded by decompression evaporates by exchanging heat with the outdoor air sent by the outdoor fan 126 in the outdoor heat exchanger 124. In the refrigerant circuit 200, the refrigerant that has passed through the outdoor heat exchanger 124 is sucked into the compressor 122 and compressed.

(1-2) Cooling Operation

When the indoor unit 110 receives a signal for an execution instruction of a cooling operation from the remote controller 150, the air conditioner 100 starts the cooling operation. During the cooling operation, the air conditioner 100 switches the four-way valve 123 to the second state. The air conditioner 100 adjusts the rotational speed of the compressor 122, the opening degree of the expansion valve 125, and the rotational speed of the indoor fan 112 to match the room temperature with a set temperature received, for example, from the remote controller 150. Additionally, the air conditioner 100 adjusts the rotational speed of the indoor fan 112 to achieve a set volume of air received, for example, from the remote controller 150. In the cooling operation, the outdoor heat exchanger 124 functions as a radiator for the refrigerant, and the indoor heat exchanger 1 functions as an evaporator for the refrigerant.

During the cooling operation, in the refrigerant circuit 200, a high-temperature, high-pressure refrigerant discharged from the compressor 122 releases heat by exchanging heat with the outdoor air sent by the outdoor fan 126 in the outdoor heat exchanger 124. The refrigerant cooled in the outdoor heat exchanger 124 passes through the expansion valve 125 and is decompressed. The refrigerant expanded by decompression evaporates by exchanging heat with the indoor air sent by the indoor fan 112 in the indoor heat exchanger 1. The indoor air cooled in the indoor heat exchanger 1 is blown back into the room as conditioned air. In the refrigerant circuit 200, the refrigerant that has passed through the indoor heat exchanger 1 is sucked into the compressor 122 and compressed.

(2) Detailed Configuration

(2-1) Indoor Heat Exchanger 1

In the present embodiment, the indoor heat exchanger 1 includes three heat exchange sections: a first heat exchange section 11, a second heat exchange section 12, and a third heat exchange section 13. The difference between the first heat exchange section 11, the second heat exchange section 12, and the third heat exchange section 13 is the arrangement position inside the casing 111. In the present embodiment, a case will be described in which the first heat exchange section 11, the second heat exchange section 12, and the third heat exchange section 13 have an identical structure. Therefore, in the following description, the structure of the first heat exchange section 11 will be described as an example, and descriptions of the structures of the second heat exchange section 12 and the third heat exchange section 13 will be omitted. However, even in a case where the structures of the first heat exchange section 11, the second heat exchange section 12, and the third heat exchange section 13 are not identical, the heat exchanger according to the present disclosure can still be applied. Note that the arrangement of the first heat exchange section 11, the second heat exchange section 12, and the third heat exchange section 13 inside the casing 111 will be described later. Note that, in a case where the first heat exchange section 11, the second heat exchange section 12, and the third heat exchange section 13 are collectively referred to, the first heat exchange section 11, the second heat exchange section 12, and the third heat exchange section 13 are referred to as a heat exchange section 10.

FIG. 5 illustrates a state in which the first heat exchange section 11 is viewed obliquely from above. FIG. 6 illustrates an enlarged cross section of the first heat exchange section 11 taken along plane B in FIG. 5. FIG. 7 illustrates the first heat exchange section 11 as viewed along a thickness direction of a flat tube 20. Respective directions such as a width direction (first direction), the thickness direction (second direction), and a longitudinal direction of the flat tube 20 used in the following description follow the directions indicated by arrows in FIGS. 5, 6, and 7. The width direction of the flat tube 20 coincides with the first direction in which air that undergoes heat exchange in the indoor heat exchanger 1 passes. The thickness direction of the flat tube 20 coincides with the second direction intersecting the first direction.

The first heat exchange section 11 includes a plurality of flat tubes 20, a plurality of fins 30, a first header 41, a second header 42, and a third header 43. The first heat exchange section 11 is a stacked heat exchanger in which the plurality of flat tubes 20 are stacked at predetermined intervals in the thickness direction of the flat tube 20 using the plurality of fins 30. In the present embodiment, the indoor heat exchanger 1 includes an inner heat exchange section 10i and an outer heat exchange section 10o.

The flat tube 20 is a heat transfer tube in which a refrigerant flows. The flat tube 20 is formed in a flat oval shape in cross section. The flat tube 20 is a multi-hole tube having a plurality of refrigerant flow paths 201 formed so as to be orthogonal to the cross section. The plurality of refrigerant flow paths 201 are arranged to be aligned in the width direction of the flat tube 20. The flat tube 20 is formed by extrusion molding using, for example, aluminum or an aluminum alloy. In the present embodiment, the flat tube 20 is arranged along a longitudinal direction of the indoor unit 110. The flat tube 20 has two side surfaces 211 and 212. The two side surfaces 211 and 212 spread in the width direction and the longitudinal direction.

The fin 30 is a band-shaped plate member through which the plurality of flat tubes 20 pass at regular intervals. The fin 30 has a plurality of through hole portions 310 provided for being inserted by the flat tubes 20. The through hole portion 310 is a peripheral edge of a slit-shaped cutout. The cutout of the through hole portion 310 is formed so as to extend, as viewed in a thickness direction of the fin 30, from one end edge, which extends in a longitudinal direction of the fin 30, toward the other end edge, while being orthogonal to the one end edge. The plurality of through hole portions 310 are formed at regular intervals in the longitudinal direction of the fin 30. The fin 30 is formed by using, for example, aluminum or an aluminum alloy.

The flat tube 20 is inserted into the through hole portion 310 such that the width direction of the flat tube 20 coincides with the insertion direction into the cutout of the through hole portion 310. The plurality of fins 30 are aligned at predetermined intervals in the longitudinal direction of the flat tube 20. In other words, the predetermined intervals refer to a fin pitch. The fins 30 and the flat tubes 20 are joined by brazing at the through hole portions 310. The plurality of flat tubes 20 are joined to the fins 30 such that end portions of the flat tubes 20 are aligned in the thickness direction of the flat tube 20. In other words, the plurality of flat tubes 20 are joined to the fins 30 to be aligned in a plurality of stages. FIGS. 5 and 7 illustrate an outer edge formed by a plurality of fins 30 aligned in the longitudinal direction of the flat tube 20 and portions of a plurality of fins 30.

The inner heat exchange section 10i and the outer heat exchange section 10o are each formed by joining a predetermined number of flat tubes 20 to a predetermined number of fins 30, and are formed in substantially an identical shape. The inner heat exchange section 10i is disposed at a position closer to the indoor fan 112 than the outer heat exchange section 10o. The inner heat exchange section 10i and the outer heat exchange section 10o are arranged so as to overlap in the thickness direction of the flat tube 20. In other words, the first heat exchange section 11 includes two rows: the inner heat exchange section 10i and the outer heat exchange section 10o. Moreover, the number of flat tubes 20 in each row corresponds to the number of stages in the first heat exchange section 11. Gaps formed between respective adjacent flat tubes 20 of the inner heat exchange section 10i and the outer heat exchange section 10o and gaps formed between respective adjacent fins 30 of the inner heat exchange section 10i and the outer heat exchange section 10o form flow paths through which an airflow generated by the indoor fan 112 flows. In FIG. 6, broken-line arrows indicate the flow of the airflow flowing through the flow paths.

The first header 41, the second header 42, and the third header 43 are tubular members that allow the refrigerant flow paths 201 of the plurality of flat tubes 20 to communicate with each other at the end portions of the plurality of flat tubes 20.

The first header 41 is provided at one ends of the flat tubes 20 included in the inner heat exchange section 10i in the longitudinal direction so as to allow the refrigerant flow paths 201 of the plurality of flat tubes 20 to communicate with each other. Specifically, the one ends of the plurality of flat tubes 20 included in the inner heat exchange section 10i in the longitudinal direction are inserted into the first header 41 through openings formed in a side surface of the first header 41, and are fixed to the first header 41 using brazing or the like.

The second header 42 is provided at the other ends of the flat tubes 20 included in the inner heat exchange section 10i in the longitudinal direction and the other ends of the flat tubes 20 included in the outer heat exchange section 10o in the longitudinal direction so as to allow the refrigerant flow paths 201 of the plurality of flat tubes 20 of the inner heat exchange section 10i and the refrigerant flow paths 201 of the plurality of flat tubes 20 of the outer heat exchange section 10o to communicate with each other. Specifically, the other ends of the flat tubes 20 included in the inner heat exchange section 10i in the longitudinal direction and the other ends of the flat tubes 20 included in the outer heat exchange section 10o in the longitudinal direction are inserted into the second header 42 through openings formed in a side surface of the second header 42, and are fixed to the second header 42 using brazing or the like.

The third header 43 is provided at one ends of the flat tubes 20 included in the outer heat exchange section 10o in the longitudinal direction so as to allow the refrigerant flow paths 201 of the plurality of flat tubes 20 to communicate with each other. Specifically, the one ends of the plurality of flat tubes 20 included in the outer heat exchange section 10o in the longitudinal direction are inserted into the third header 43 through openings formed in a side surface of the third header 43, and are fixed to the third header 43 using brazing or the like. The third header 43 is connected to the connection pipe 132 via branch pipes 431.

The refrigerant that has passed through the connection pipe 131 and flowed into the first header 41 passes through the plurality of refrigerant flow paths 201 formed in the flat tubes 20 of the inner heat exchange section 10i and flows into the second header 42. The refrigerant that has flowed into the second header 42 passes through the plurality of refrigerant flow paths 201 formed in the outer heat exchange section 10o, passes through the third header 43, and flows into the connection pipe 132. Additionally, the refrigerant that has passed through the connection pipe 132 and flowed into the first header 41 passes through the plurality of refrigerant flow paths 201 formed in the flat tubes 20 of the outer heat exchange section 10o and flows into the third header 43. The refrigerant that has flowed into the third header 43 passes through the plurality of refrigerant flow paths 201 formed in the inner heat exchange section 10i, passes through the first header 41, and flows into the connection pipe 131.

The first heat exchange section 11 is, when the indoor unit 110 is viewed from a side (viewed in the horizontal direction along the wall WL), provided such that the thickness direction of the flat tube 20 is inclined rearward with respect to the up-down direction (vertical direction). As a result, the upper end of the first heat exchange section 11 is disposed to be closer to the wall WL than the lower end. The second heat exchange section 12 is, when the indoor unit 110 is viewed from the side, provided such that the thickness direction of the flat tube 20 is inclined frontward with respect to the up-down direction (vertical direction). As a result, the lower end of the second heat exchange section 12 is disposed to be closer to the wall WL than the upper end. The third heat exchange section 13 is, when the indoor unit 110 is viewed from the side, provided such that the thickness direction of the flat tube 20 is inclined frontward with respect to the up-down direction (vertical direction). As a result, the lower end of the third heat exchange section 13 is disposed to be closer to the wall WL than the upper end.

(2-1-1) Fin 30

FIG. 8 illustrates a portion of a single fin 30. Each fin 30 includes a plurality of through hole portions 310, one connecting portion 320, and a plurality of heat transfer portions 330. The connecting portion 320 is a portion continuously extending in the second direction. A chain line extending in the second direction illustrated in FIG. 8 is a boundary line between the heat transfer portions 330 and the connecting portion 320. The through hole portion 310 is a peripheral edge around the cutout. A collar 311 rising along the flat tube 20 is formed on the peripheral edge. In the present embodiment, the collar 311 corresponds to the through hole portion 310. The direction along the flat tube 20 is a direction intersecting the first direction and the second direction. The heat transfer portions 330 are portions other than the through hole portions 310 and the connecting portion 320.

Each fin 30 further includes fin pitch defining portions 340, bridge-shaped cut-and-raised portions 350, and protrusions 360. The fin pitch defining portions 340, the cut-and-raised portions 350, and the protrusions 360 are structures formed in the heat transfer portions 330. The fin pitch defining portion 340 is in contact with an adjacent fin 30 and defines the fin pitch. The fin pitch of the adjacent fin 30 is determined by a height h1 (see FIG. 10) of the fin pitch defining portion 340. The fin pitch defining portion 340 includes two or more raised portions 341 formed by cutting and raising, in two or more directions, the heat transfer portion 330 of each fin 30, the heat transfer portion 330 being located at a position other than the connecting portion 320. Therefore, gaps 342 are formed between the raised portions 341. In each fin 30, one fin pitch defining portion 340 is provided for every N (N being an integer of two or more) flat tubes 20. In a case where the number of fin pitch defining portions 340 in each fin 30 is three or more, it is preferable that the three or more fin pitch defining portions 340 of each fin 30 be arranged such that the number of flat tubes 20 between adjacent fin pitch defining portions 340 is identical. For example, if the number of fin pitch defining portions 340 of each fin 30 is four and N=4, the structure illustrated in FIG. 10 is arranged first, followed by the structure illustrated in FIG. 9 repeated three times. Then, the structure illustrated in FIG. 10 is arranged, followed by the structure illustrated in FIG. 9 repeated three times again. Then, the structure illustrated in FIG. 10 is arranged, followed by the structure illustrated in FIG. 9 repeated three times again, and then the structure illustrated in FIG. 10 is arranged.

The collar 311 of the through hole portion 310 can be divided into a first upright portion 316 and a second upright portion 317. In the collar 311, the first upright portion 316 is a portion that rises along the flat tube 20 passing through and is in contact with an adjacent fin 30. In contrast, the second upright portion 317 is a portion that rises along the flat tube 20 passing through but is not in contact with the adjacent fin 30. The first upright portion 316 is disposed on only one of two opposing sides 318 and 319 (see FIG. 8) of the cutout.

The first upright portion 316 assists in maintaining the fin pitch defined by the fin pitch defining portion 340. Additionally, the first upright portion 316 suppresses buckling of the fin 30 during insertion of the flat tube 20. In order to facilitate the suppression of buckling, the first upright portion 316 is preferably provided at the entrance of the cutout of the through hole portion 310. Additionally, a length L2 of the first upright portion 316 is preferably 50% or less of a length L1 of the fin 30 in the first direction. In order to stably support the fin 30, the surface of the first upright portion 316 that is in contact with the adjacent fin 30 is preferably rectangular.

(2-1-2) Specific Configuration of Fin Pitch Defining Portion 340

FIG. 8 illustrates a portion of the fin 30 in a case where N is four. FIG. 9 illustrates a portion of the fin 30 where the fin pitch defining portion 340 is not formed between adjacent flat tubes 20. FIG. 10 illustrates a portion of the fin 30 where the fin pitch defining portion 340 is formed between adjacent flat tubes 20. In a case where N=4, one fin pitch defining portion 340 is provided for every four flat tubes 20. In other words, in a case where N=4, four flat tubes 20 are disposed between two adjacent fin pitch defining portions 340 in each fin 30.

As illustrated in FIG. 9, three bridge-shaped cut-and-raised portions 350 are formed in the heat transfer portion 330 of the fin 30 where the fin pitch defining portion 340 is not formed. In contrast, as illustrated in FIG. 10, only one bridge-shaped cut-and-raised portion 350 is formed in the heat transfer portion 330 where the fin pitch defining portion 340 is formed. At the bridge-shaped cut-and-raised portion 350, the airflow passing through the flat, uncut-and-unraised portion of the heat transfer portion 330 passes along both surfaces of the cut-and-raised portion 350. Such a bridge-shaped cut-and-raised portion 350 may be referred to as a slit in some cases. The heat transfer portion 330 in which three bridge-shaped cut-and-raised portions 350 are formed enables more efficient heat exchange compared to the heat transfer portion 330 in which one bridge-shaped cut-and-raised portion 350 is formed.

There are four gaps 342 between four raised portions 341 of the fin pitch defining portion 340. Two of the four gaps 342 are arranged to be aligned in the first direction, and the remaining two are arranged to be aligned in the second direction. The raised portions 341 are formed by creating a cross-shaped cutting line in the flat heat transfer portion 330 and cutting and raising the flat heat transfer portion 330 so that the fold lines form a circle. This allows the airflow flowing in the first direction to easily pass through the two gaps 342. Additionally, condensed water flows easily by passing through the other two gaps 342 in the second direction.

(2-1-3) Fin Pitch Defining Portion and Heat Transfer Coefficient

The graph illustrated in FIG. 11 indicates a relationship between the fin pitch defining portion 340 and heat transfer. The graph illustrated in FIG. 11 indicates air-side heat transfer coefficients (W/m²) for Configuration X1 using the fin 30 illustrated in FIG. 12, Configuration Y1 using a fin 530 illustrated in FIG. 13, Configuration Y2 using a fin 630 illustrated in FIG. 14, and Configuration Y3 using a fin 730 illustrated in FIG. 14. These graphs are provided for comparing the differences in the amounts of heat transferred from the fins 30, 530, 630, and 730 to the air under the same conditions, where the fins 30, 530, 630, and 730 have an identical area and an identical temperature, and the air temperature is also identical. As a fin having a higher air-side heat transfer coefficient is used, a heat exchanger having a higher heat exchange efficiency can be obtained. The graph indicates the measurement results for three rows of fins under the conditions of a row pitch of 10 mm and a stage pitch of 9.7 mm. The air flow direction is the direction indicated by an arrow AF.

The horizontal axis “N” of the graph corresponds to the number of flat tubes 20 for one fin pitch defining portion 340 or 540 in each fin of Configurations X1 and Y1. The case where N=1 is a case where the fin pitch defining portion 340 or 540 is formed in all the heat transfer portions 330. In other words, the case where N=1 is a case where the structure illustrated in FIG. 9 does not appear in any of the fins 30 and 530. The case where N=2 is a case where two flat tubes 20 are disposed between adjacent fin pitch defining portions 340 or 540. In other words, the case where N=2 is a case where the structure illustrated in FIG. 9 and the structure illustrated in FIG. 10 appear alternately in each fin 30, for example. The case where N=3 is a case where three flat tubes 20 are disposed between adjacent fin pitch defining portions 340 or 540. In other words, the case where N=3 is a case where the structure illustrated in FIG. 9 appears twice in succession, and then the structure illustrated in FIG. 10 appears once in each fin 30, for example.

Configuration X1 illustrated in FIG. 12 is a configuration using the fin 30 according to the above embodiment, in which the fin pitch defining portion 340, one bridge-type cut-and-raised portion 350, and the protrusions 360 are provided in the heat transfer portion 330, and the first upright portion 316 is provided on the through hole portion 310. The difference between Configuration X1 illustrated in FIG. 12 and Configuration Y1 illustrated in FIG. 13 lies in the structure of the fin pitch defining portions 340 and 540. The gaps 342 exist in the fin pitch defining portion 340, whereas no structure corresponding to the gap 342 exists in the fin pitch defining portion 540. The fin pitch defining portion 340 in FIG. 12 has four raised portions 341, whereas the fin pitch defining portion 540 in FIG. 13 has only one circularly raised portion. Configuration Y2 illustrated in FIG. 14 has two spacers 640, disclosed in PTL 1, provided in the heat transfer portion 330. Therefore, only one bridge-type cut-and-raised portion 350 is provided in the heat transfer portion 330. Accordingly, Configuration Y2 illustrated in FIG. 14 exhibits a low air-side heat transfer coefficient, as indicated by a broken line graph in FIG. 11. Configuration Y3 illustrated in FIG. 15 has a fin pitch defining portion 740 provided on a through hole portion 710. Configuration Y3, described above, in which the fin pitch defining portion 740 is provided only on the through hole portion 710 is difficult to manufacture and not practical, but three bridge-type cut-and-raised portions 350 can be provided in all the heat transfer portions 330. Therefore, Configuration Y3 illustrated in FIG. 15 exhibits a good air-side heat transfer coefficient, as indicated by a chain line graph in FIG. 11.

The air-side heat transfer coefficients for Configurations X1 and Y1 illustrated in FIGS. 12 and 13 are both inferior to the air-side heat transfer coefficient for Configuration Y2 when N=1. However, the air-side heat transfer coefficients for Configurations X1 and Y1 illustrated in FIGS. 12 and 13 become better than the air-side heat transfer coefficient for Configuration Y2 when N=2 or more. Furthermore, as N increases, such as N=4 to N=6, the air-side heat transfer coefficients for Configurations X1 and Y1 approach the air-side heat transfer coefficient for Configuration Y3 illustrated in FIG. 15. Moreover, when Configuration X1 illustrated in FIG. 12 is compared with Configuration Y1 illustrated in FIG. 13, the value of the air-side heat transfer coefficient for Configuration X1 is higher than the value of the air-side heat transfer coefficient for Configuration Y1 regardless of the value of N.

(3) Modifications

(3-1) Modification A

In the above embodiment, the case where the indoor unit 110 is of a wall-hung type has been described. However, the indoor unit to which the indoor heat exchanger 1 described in the above embodiment can be applied is not limited to the wall-hung type. The indoor heat exchanger 1 according to the present disclosure can be applied to, for example, a duct-type indoor unit, as illustrated in FIG. 16, which is embedded in a ceiling and distributes conditioned air through ducts. In FIG. 16, the indoor fan 112 generates an airflow in the indoor heat exchanger 1. For example, a centrifugal fan can be used as the indoor fan 112 in FIG. 16. For example, a sirocco fan can be used as the centrifugal fan. The shape of the indoor heat exchanger 1 illustrated in FIG. 16 is I-shaped when viewed from the side, but for example, the shape when viewed from the side may be bent into a wedge shape, as illustrated in FIG. 17. In this case, as illustrated in FIG. 17, a cross-flow fan may be used as the indoor fan 112, for example. Alternatively, a centrifugal fan may be used instead of the cross-flow fan. In FIG. 17, a two-dot chain line arrow AF indicates the direction in which air flows. As illustrated in FIG. 18, the heat exchanger 1 can also be arranged in an N-shape when viewed from the side. The indoor unit 110 in FIG. 18 is configured such that air flows from the bottom to the top in the direction of gravity, as indicated by the arrow AF, by the indoor fan 112. The configuration of the indoor unit 110 in FIG. 18 can be modified such that air flows from the top to the bottom.

(3-2) Modification B

In the above embodiment, the case where the fin pitch defining portion 340 has four raised portions 341 has been described. However, as illustrated in FIG. 19, the number of raised portions 341 in one fin pitch defining portion 340 may be three, for example. In this case, as illustrated in FIG. 19, the gaps 342 between adjacent raised portions 341 are arranged offset in the flow direction of air (first direction), allowing airflow resistance to be easily reduced. Additionally, the gaps 342 between adjacent raised portions 341 are arranged to be aligned with the flow direction of condensed water (second direction), allowing the condensed water to flow more easily.

Additionally, the number of raised portions 341 of the fin pitch defining portion 340 can be set to two. In a case where the number of raised portions 341 is set to two, arranging two gaps 342 to be aligned with the flow direction of air (first direction) allows the airflow to flow more easily. In a case where the number of raised portions 341 is set to two, arranging the two gaps 342 to be aligned with the flow direction of condensed water (second direction) allows the condensed water to flow more easily. Note that the sizes of the two or more raised portions 341 may, for example, be identical as in the above embodiment, but, as illustrated in FIG. 19, the sizes do not necessarily need to be identical.

(3-3) Modification C

In the above embodiment, the case where the fin pitch defining portion 340 and the first upright portion 316 are used in combination has been described. However, the fin pitch defining portion 340 and the first upright portion 316 do not necessarily need to be used in combination. For example, it is possible to configure the structure by providing the fin pitch defining portion 340 while not providing the first upright portion 316. Additionally, the first upright portion 316 may also be used in combination with a fin pitch defining portion other than the fin pitch defining portion 340.

(3-4) Modification D

In the above embodiment, the case where the through hole portion 310 is provided with the collar 311 has been described. However, it is also possible to configure the through hole portion 310 so that only the first upright portion 316 rises without providing the collar 311.

(3-5) Modification E

In the above embodiment, the case where the bridge-type cut-and-raised portion 350 is formed in the heat transfer portion 330 has been described. However, the structure for promoting heat exchange is not limited to the bridge-type cut-and-raised portion 350 (slit). For example, the structure for promoting heat exchange may be a louver-type cut-and-raised portion formed by cutting and raising the heat transfer portion 330 obliquely to the plane of the heat transfer portion 330.

(4) Features

4-1

In the above embodiment or modifications, each fin 30 includes a plurality of through hole portions 310, a connecting portion 320, and one or more fin pitch defining portions 340. A plurality of flat tubes 20 pass through the plurality of through hole portions 310. The connecting portion 320 extends in the second direction intersecting the first direction without being passed through by the plurality of flat tubes 20. The one or more fin pitch defining portions 340 are in contact with an adjacent fin 30 and define the fin pitch. In each fin 30, one fin pitch defining portion 340 is provided for every N (N being an integer of two or more) flat tubes 20. The fin pitch defining portion 340 of each fin 30 includes two or more raised portions 341 formed by cutting and raising, in two or more directions, the heat transfer portion 330 of each fin 30, the heat transfer portion 330 being located at a position other than the connecting portion 320. Since the two or more raised portions 341 of the fin pitch defining portion 340 are cut and raised in two or more directions, gaps 342 are formed between the two or more raised portions 341, and it is possible to prevent at least one of an air flow path and a water drainage path from being narrowed at the fin pitch defining portion 340. As a result, it is possible to suppress a reduction in heat exchange efficiency or water drainage performance due to the fin pitch defining portion 340.

4-2

In a case where the fin pitch defining portion 340 includes three raised portions 341 formed by cutting and raising in three directions, as illustrated in FIG. 19 described in the modification B, the fin pitch defining portion 340 can support an adjacent fin 30 at three points using the three raised portions 341. As a result, the fin pitch defining portion 340 can securely support the adjacent fin 30 and stably define the fin pitch. Additionally, since the fin pitch defining portion 340 including the three raised portions 341 has three gaps 342, the arrangement of the gaps 342 can prevent at least one of the air flow path and the water drainage path from being narrowed at the fin pitch defining portion 340.

4-3

The fin pitch defining portion 340 in the above embodiment includes four raised portions 341 formed by cutting and raising in four directions. Since the four raised portions 341 of the fin pitch defining portion 340 are cut and raised in four directions, two gaps 342 can be arranged to be aligned in the first direction, and the other two gaps 342 can be arranged to be aligned in the second direction. The two gaps 342 arranged to be aligned in the first direction can prevent the air flow path from being narrowed. Additionally, the two gaps 342 arranged to be aligned in the second direction can prevent the water drainage path from being narrowed. As a result, the arrangement of the gaps 342 can prevent both the air flow path and the water drainage path from being narrowed at the fin pitch defining portion 340.

4-4

As indicated by the graph of Configuration X1 in FIG. 11, the reduction in the heat transfer coefficient can be suppressed by reducing the proportion of the portion where the fin pitch defining portions 340 are provided in each fin 30, such as by providing one fin pitch defining portion 340 for every four flat tubes or one for every six flat tubes. Reducing the proportion of the portion where the fin pitch defining portions 340 are provided means increasing the value of N, in other words, reducing the value of (the number of configurations in FIG. 10/the number of configurations in FIG. 9) in each fin 30.

4-5

In the above embodiment, in a case where the number of fin pitch defining portions 340 in each fin 30 is three or more, it is preferable that the three or more fin pitch defining portions 340 of each fin 30 be arranged such that the number of flat tubes 20 between adjacent fin pitch defining portions 340 is identical. With such an arrangement, portions, where the heat transfer coefficient is reduced due to the arrangement of the fin pitch defining portions 340, are arranged regularly, which makes it possible to suppress the overall reduction in the heat transfer coefficient compared to a case where the portions are arranged irregularly.

4-6

Each through hole portion 310 of each fin 30 in the above embodiment includes: the first upright portion 316 that rises along a corresponding flat tube 20 and is in contact with an adjacent fin 30; and a second upright portion 317 that rises along the corresponding flat tube 20 and is not in contact with the adjacent fin 30. Since the first upright portion 316 of the through hole portion 310 is in contact with the adjacent fin 30, it is possible to suppress the occurrence of buckling during insertion into the flat tube 20. Additionally, the first upright portion 316 can assist in securing the fin pitch.

4-7

Each through hole portion 310 of each fin 30 in the above embodiment includes the first upright portion 316 that rises along a corresponding flat tube 20 and is in contact with an adjacent fin 30. In a case where there is another portion that defines the fin pitch in addition to the first upright portion 316, the first upright portion 316 can suppress buckling and crushing of the fin during insertion of the flat tube 20, and assist in securing the fin pitch by another portion that defines the fin pitch. In the above embodiment, another portion that defines the fin pitch is the fin pitch defining portion 340, but another portion that defines the fin pitch is not limited to the fin pitch defining portion 340.

4-8

The first upright portion 316 in the above embodiment is provided only on one of two side surfaces 211 and 212 (see FIG. 6) of each flat tube 20 in the longitudinal direction of each fin 30. In other words, the first upright portion 316 is disposed on only one of two opposing sides 318 and 319 (see FIG. 8) of the cutout of the through hole portion 310. Since the first upright portion 316 is provided only on one of the two side surfaces of the flat tube 20, the height of the first upright portion 316 can be increased to a height close to the thickness of the flat tube 20, compared to a case where the first upright portion 316 is provided on both sides.

The embodiment of the present disclosure has been described heretofore, and it will be understood that a variety of modifications in mode and detail may be made without departing from the gist and scope of the present disclosure as set forth in claims.

Claims

1. A heat exchanger comprising: a plurality of fins; anda plurality of flat tubes, the heat exchanger being configured to perform heat exchange of air passing in a first direction between the plurality of flat tubes and the plurality of fins,each of the fins including a plurality of through hole portions through which the plurality of flat tubes pass,a connecting portion that extends in a second direction intersecting the first direction without being passed through by the plurality of flat tubes, andat least one fin pitch defining portion in contact with an adjacent fin and defining a fin pitch,in each of the fins, one fin pitch defining portion being provided for every N flat tubes, where N is an integer of at least two, andthe fin pitch defining portion of each of the fins including at least two raised portions formed by cutting and raising, in at least two directions, a heat transfer portion of each of the fins, the heat transfer portion being located at a position other than the connecting portion.

2. The heat exchanger according to claim 1, wherein the fin pitch defining portion of each of the fins includes three raised portions formed by cutting and raising, in three directions, the heat transfer portion of each of the fins, the heat transfer portion being located at the position other than the connecting portion.

3. The heat exchanger according to claim 1, wherein the fin pitch defining portion of each of the fins includes four raised portions formed by cutting and raising, in four directions, the heat transfer portion of each of the fins, the heat transfer portion being located at the position other than the connecting portion.

4. The heat exchanger according to claim 1, wherein the number of flat tubes is at least four, andone fin pitch defining portion is provided for every four flat tubes.

5. The heat exchanger according to claim 1, wherein the number of flat tubes is at least six, andone fin pitch defining portion is provided for every six flat tubes.

6. The heat exchanger according to claim 1, wherein a number of fin pitch defining portions in each of the fins is at least three, andthe at least three fin pitch defining portions of each of the fins are arranged such that a number of flat tubes between adjacent fin pitch defining portions is identical.

7. The heat exchanger according to claim 1, wherein each of the through hole portions of each of the fins includes a first upright portion that rises along a corresponding flat tube and is in contact with an adjacent fin, anda second upright portion that rises along the corresponding flat tube and is not in contact with the adjacent fin.

8. The heat exchanger according to claim 1, wherein air passing in the first direction is indoor air that undergoes heat exchange in an indoor unit that performs indoor air conditioning.

9. The heat exchanger according to claim 2, wherein the number of flat tubes is at least four, andone fin pitch defining portion is provided for every four flat tubes.

10. The heat exchanger according to claim 2, wherein the number of flat tubes is at least six, andone fin pitch defining portion is provided for every six flat tubes.

11. The heat exchanger according to claim 2, wherein a number of fin pitch defining portions in each of the fins is at least three, andthe at least three fin pitch defining portions of each of the fins are arranged such that a number of flat tubes between adjacent fin pitch defining portions is identical.

12. The heat exchanger according to claim 2, wherein each of the through hole portions of each of the fins includes a first upright portion that rises along a corresponding flat tube and is in contact with an adjacent fin, anda second upright portion that rises along the corresponding flat tube and is not in contact with the adjacent fin.

13. The heat exchanger according to claim 3, wherein the number of flat tubes is at least four, andone fin pitch defining portion is provided for every four flat tubes.

14. The heat exchanger according to claim 3, wherein the number of flat tubes is at least six, andone fin pitch defining portion is provided for every six flat tubes.

15. The heat exchanger according to claim 3, wherein a number of fin pitch defining portions in each of the fins is at least three, andthe at least three fin pitch defining portions of each of the fins are arranged such that a number of flat tubes between adjacent fin pitch defining portions is identical.

16. The heat exchanger according to claim 3, wherein each of the through hole portions of each of the fins includes a first upright portion that rises along a corresponding flat tube and is in contact with an adjacent fin, anda second upright portion that rises along the corresponding flat tube and is not in contact with the adjacent fin.

17. A heat exchanger comprising: a plurality of flat tubes; anda plurality of fins,each of the fins including a plurality of through hole portions through which the plurality of flat tubes pass, andeach of the through hole portions including a first upright portion that rises along a corresponding flat tube and is in contact with an adjacent fin.

18. The heat exchanger according to claim 17, wherein the first upright portion is provided only on one of two side surfaces of each of the flat tubes in a longitudinal direction of each of the fins.

19. The heat exchanger according to claim 18, wherein each of the through hole portions includes, as a portion other than the first upright portion, a second upright portion that rises along the corresponding flat tube and is not in contact with the adjacent fin, andthe first upright portion rises higher than the second upright portion.

20. The heat exchanger according to claim 17, wherein each of the through hole portions includes, as a portion other than the first upright portion, a second upright portion that rises along the corresponding flat tube and is not in contact with the adjacent fin, andthe first upright portion rises higher than the second upright portion.