JP2016099037A - Heat exchanger of refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger of a refrigeration cycle device in which corrosion is suppressed and which is low in cost.SOLUTION: The heat exchanger of a refrigeration cycle device includes: a heat transfer pipe 30 in which a refrigerant flows; and a plurality of fins 20 which are laminated with each other, in which the heat transfer pipe 30 penetrates, and in which a through-hole 20a having a folded part 20b standing in a cylindrical shape is formed. The fin 20 and the heat transfer pipe 30 use aluminum or aluminum alloy as a material, and the fin 20 and the heat transfer pipe 30 are bonded by brazing 15 via the through-hole 20a and the folded part 20b, and a distance h between a tip 20b1 of the folded part 20b and a surface of the heat transfer pipe 30 is equal to or less than 0.1 mm.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a heat exchanger of a refrigeration cycle apparatus.

  Conventionally, as a heat exchanger used in a refrigeration cycle apparatus such as an air conditioner, a cross fin tube type heat generally composed of a plurality of aluminum (hereinafter referred to as aluminum alloy) fins and a plurality of copper heat transfer tubes. An exchanger is known. The cross fin tube type heat exchanger is configured to penetrate a large number of thin plate-like fins while a plurality of copper heat transfer tubes are in contact therewith. Then, the refrigerant flows through the copper heat transfer tube, and heat exchange between the outside air and the refrigerant is performed through fins having a large heat transfer area.

  By the way, in recent years, a heat exchanger in which the material of the heat transfer tube is changed from copper to aluminum has been used for the purpose of reducing the weight and cost of the heat exchanger. In general, aluminum has a higher tendency to corrode than most metals except for some metals such as magnesium and potassium because of its high ionization tendency. That is, aluminum is easily eluted as a cation and has a low corrosion potential. Therefore, in the case of aluminum, compared to a copper heat transfer tube, the tendency to corrode is large, and as a result, a minute through hole is likely to be generated in the heat transfer tube, and the refrigerant is likely to leak.

  As a countermeasure, a sacrificial anticorrosive layer containing zinc having a higher corrosion tendency than aluminum, that is, having a lower corrosion potential (easily becomes a cation) is formed on the surface of the heat transfer tube made of aluminum. Alternatively, zinc or the like is added to the fin material itself to develop a sacrificial anticorrosive effect and improve the corrosion resistance of the heat transfer tube. (See Patent Document 1 and Non-Patent Document 1)

JP 2010-85066 A

Light metal Vol. 41 (1991), p. 208

  By the way, in the cross fin tube type heat exchanger composed of the above-described aluminum fins and heat transfer tubes, through holes having a diameter larger than the outer diameter of the heat transfer tubes are formed in the fins. Then, the heat transfer tube is passed through the through hole. After that, a sphere having a diameter larger than the inner diameter of the heat transfer tube is passed inside the heat transfer tube, the tube is expanded by applying mechanical pressure to the heat transfer tube, and the outer diameter is increased so that the fin is pressed against the heat transfer tube. ing. After pressure welding, due to changes over time, temperature changes, etc., gaps occur between adjacent fins in the vicinity of the heat transfer tube, gaps between the heat transfer tube surface and the fin due to the undulation of the surface of the heat transfer tube, and bending of the fins A gap is generated due to deformation of the portion (color).

If moisture containing a substance that induces corrosion enters once in these small gaps, it takes time until the moisture exudes, and it will be exposed to a corrosive environment for a long time.
Even when moisture evaporates due to drying, the substance that induces corrosion remains. For this reason, when water enters again, the concentration of the substance that induces corrosion increases, which further deteriorates the corrosive environment. In such an environment, even if measures such as Patent Document 1 and Non-Patent Document 1 are taken, it is estimated that the aluminum heat transfer tube is easily corroded.

  The present invention has been devised in view of the above circumstances, and an object thereof is to provide a heat exchanger for a low-cost refrigeration cycle apparatus in which corrosion of an aluminum heat transfer tube is suppressed.

  In order to solve the above problems, the heat exchanger of the refrigeration cycle apparatus of the present invention is formed with a heat transfer tube through which a refrigerant flows and a through-hole that is laminated with each other and has a bent portion that rises in a cylindrical shape while passing through the heat transfer tube. A heat exchanger of a refrigeration cycle apparatus comprising a plurality of fins, wherein the fins and the heat transfer tubes are made of aluminum or aluminum alloy, and the fins and the heat transfer tubes include the through holes and the heat transfer tubes. It is characterized by being joined by brazing via a bent portion, and the distance between the tip of the bent portion and the heat transfer tube surface is 0.1 mm or less.

  ADVANTAGE OF THE INVENTION According to this invention, corrosion is suppressed and the heat exchanger of the low-cost refrigeration cycle apparatus is realizable.

1 is a system diagram of a refrigeration cycle apparatus showing a refrigeration cycle apparatus according to Embodiment 1 of the present invention. The principal part perspective view of the cross fin tube type heat exchanger used for a heat source side heat exchanger. The AA sectional view of Drawing 2 showing the section in the joined part of a fin and a heat exchanger tube. (a) is an AA cross section equivalent view in the junction part of the fin and heat exchanger tube before pipe expansion shown in FIG. 2, (b) is an AA cross section equivalent figure in the junction part of the fin and the heat transfer pipe after pipe expansion. FIG. 2A is a cross-sectional view corresponding to the AA cross section of FIG. 2 at the joint portion of the heat transfer tube after being expanded with the fin of the refrigeration cycle apparatus of Embodiment 2, and FIG. 2B is after the fin and the heat transfer tube are brazed. FIG. 3 is a cross-sectional view corresponding to AA in FIG. FIG. 2A is a cross-sectional view corresponding to AA in FIG. 2 of a cross-sectional view of a joint portion after a brazing material layer is formed on a heat transfer tube and the fins and the heat transfer tube are brazed in the refrigeration cycle apparatus of Embodiment 3. ) Is a cross-sectional view corresponding to the AA cross section of FIG. 2 of the cross-sectional view of the joint after the brazing material layer is formed on the fin and the fin and the heat transfer tube are brazed in the refrigeration cycle apparatus of the third embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
The present invention relates to the structure of a heat exchanger having an aluminum heat transfer tube used in a refrigeration cycle apparatus such as an air conditioner using a refrigeration cycle.

<< Embodiment 1 >>
FIG. 1 is a system diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention.
In the refrigeration cycle apparatus R of Embodiment 1, the outdoor unit 1 and the indoor unit 2 are connected by a liquid side connection pipe 3 and a gas side connection pipe 4 which are refrigerant pipes.
The refrigerant pipe is a pipe through which the refrigerant flows.

The outdoor unit 1 includes an accumulator 5, a compressor 6, a four-way valve 7, an outdoor heat exchanger 8, a first expansion valve 9, and the like. The outdoor unit 1 includes a liquid blocking valve 10 connected to the liquid side connecting pipe 3 and a gas blocking valve 11 connected to the gas side connecting pipe 4.
The indoor unit 2 includes a use side heat exchanger 12 and a second expansion valve 13.

<Cooling operation>
The refrigeration cycle apparatus R operates as follows when performing a cooling operation. The flow of the refrigerant during the cooling operation is indicated by a solid arrow in FIG.
The high-temperature and high-pressure gas refrigerant compressed by the compressor 6 is discharged from the compressor 6 together with the refrigerating machine oil, and flows into the heat source side heat exchanger 8 through the four-way valve 7. In the heat source side heat exchanger 8, the high-temperature and high-pressure gas refrigerant is condensed and liquefied by exchanging heat with outdoor air or cooling water. The liquefied refrigerant passes through the fully opened first expansion valve 9, passes through the liquid blocking valve 10 and the liquid side connection pipe 3, and is sent to the indoor unit 2.

The liquid refrigerant that has flowed into the indoor unit 2 is decompressed and expanded by the second expansion valve 13, becomes a low-temperature, low-pressure gas-liquid two-phase flow, and flows into the use-side heat exchanger 12. In the use-side heat exchanger 12, the low-temperature, low-pressure gas-liquid two-phase refrigerant exchanges heat with the use-side medium such as indoor air, takes away latent heat of evaporation, cools the use-side medium, and evaporates and vaporizes itself. Thereafter, the gas refrigerant passes through the gas side connection pipe 4, returns to the compressor 6 through the gas blocking valve 11, the four-way valve 7 (see the solid line arrow in FIG. 1), and the accumulator 5. The accumulator 5 performs gas-liquid separation and sends a gaseous refrigerant to the compressor 6.
The above is the refrigeration cycle of the cooling operation.

  Excess refrigerant in the refrigeration cycle in the cooling operation is stored in the accumulator 5 so that the operating pressure and temperature of the refrigeration cycle are maintained in a normal state.

<Heating operation>
The refrigeration cycle apparatus R operates as follows when performing the heating operation. The flow of the refrigerant during the heating operation is indicated by broken-line arrows in FIG.
The high-temperature and high-pressure gas refrigerant compressed by the compressor 6 is discharged from the compressor 6 together with the refrigerating machine oil, and passes through the four-way valve 7, the gas blocking valve 11, and the gas side connection pipe 4 to the use side heat exchanger 12 of the indoor unit 2. Inflow. In the use-side heat exchanger 12, the high-temperature and high-pressure gas refrigerant exchanges heat with the use-side medium such as indoor air and heats the use-side medium with condensation heat, and condenses and liquefies itself.

The liquefied refrigerant is reduced in pressure by the first expansion valve 9 through the liquid side connection pipe 3 and the liquid blocking valve 10 and flows into the heat source side heat exchanger 8. In the heat source side heat exchanger 8, the decompressed liquid refrigerant is evaporated and vaporized by exchanging heat with a heat source medium such as outdoor air or water. The vaporized refrigerant returns to the compressor 6 through the four-way valve 7 and the accumulator 5.
The above is the refrigeration cycle of the heating operation.

<Heat source side heat exchanger 8>
FIG. 2 is a perspective view of a main part of a cross fin tube type heat exchanger used in the heat source side heat exchanger.
The heat source side heat exchanger 8 of the refrigeration cycle apparatus R uses a cross fin tube type heat exchanger.
The heat source side heat exchanger 8 of the cross fin tube type heat exchanger includes a plurality of heat transfer tubes 30 and a plurality of fins 20 in which through holes 20a for passing the heat transfer tubes 30 are formed.

  The plurality of heat transfer tubes 30 are made of an aluminum-based material (hereinafter, including aluminum or an aluminum alloy). The plurality of fins 20 are made of an aluminum-based material (hereinafter, including aluminum or an aluminum alloy).

FIG. 3 is a cross-sectional view taken along the line AA of FIG. 2 showing a cross section at the joint between the fin and the heat transfer tube.
Each fin 20 is previously formed with a through hole 20a through which the heat transfer tube 30 passes. The through-hole 20a is first formed with an inner diameter that is larger than the outer diameter of the pipe 30a made of a material to be the heat transfer tube 30. A bent portion 20b that is brought into contact with the heat transfer tube 30 for heat transfer is formed in the through hole 20a of the fin 20 so as to protrude in a curl shape by press molding.

  The bent portion 20b is formed in a cylindrical shape that rises around a through hole 20a having a diameter larger than the outer diameter (see FIG. 4A) of the pipe 30a that is a material to be the heat transfer tube 30. And the pipe 30a of the raw material which penetrates the fin 20 is expanded, it becomes the heat exchanger tube 30, and the through-hole 20a and the heat exchanger tube 30 are press-contacted (details are mentioned later).

As shown in FIG. 3, the plurality of heat transfer tubes 30 and the plurality of fins 20 are brazed and joined by a brazing material 15.
Here, when the distance h (see FIG. 3) between the tip 20b1 of the bent portion 20b and the outer surface of the heat transfer tube 30 is too large, the volume of the region surrounded by the two adjacent fins 20 and the heat transfer tube 30 increases. . Therefore, when the molten brazing filler metal 15 is solidified, the region cannot be completely filled and a gap (unfilled space) remains.

  When moisture containing a substance that induces corrosion enters the gap (unfilled space), the moisture directly touches the aluminum heat transfer tube 30 having a low corrosion potential. For this reason, the aluminum cation of the aluminum heat transfer tube 30 is eluted by the action of a substance that induces corrosion in moisture, and corrosion may occur at an early stage.

  From the above, in order to eliminate the unfilled space of the brazing material 15, the distance h between the tip 20 b 1 of the fin bent portion 20 b and the surface of the heat transfer tube 30 should be set small enough to be filled with the solidified brazing material (fillet) 15. Is preferred.

  Therefore, the distance h between the tip 20b1 of the fin bent portion 20b and the surface of the heat transfer tube 30 is set to 0.1 mm or less. Thereby, the volume of the area | region enclosed by the two adjacent fins 20 and the heat exchanger tubes 30 can be made small enough, and an unfilled space can be eliminated.

<Example of manufacturing method of heat source side heat exchanger 8>
Next, an example of a manufacturing method of the heat source side heat exchanger 8 of the cross fin tube type heat exchanger used in the apparatus for the refrigeration cycle R described above will be described.
FIG. 4A is a cross-sectional view corresponding to the AA cross section of the joint between the fin and the heat transfer tube before the heat transfer tube is expanded, and FIG. 4B is a view of the fin after the heat transfer tube is expanded. It is an AA cross-section equivalent view of the joined part of a heat exchanger tube.

First, as shown to Fig.4 (a), the pipe 30a of the raw material used as the several heat exchanger tube 30 comprised with the aluminum-type material, and the several fin 20 comprised with the aluminum-type material are prepared. The material pipe 30a is prepared with a diameter smaller than the diameter of the heat transfer tube 30 at the time of completion.
For the fin 20, a brazing sheet is used in which a brazing material layer 22 having a main component of aluminum and a melting point lower than that of the core material 21 is bonded to the surface of the core material 21 made of an aluminum-based material. By using the brazing sheet, the brazing material layer 22 can be easily formed.

The brazing sheet is pressed to form fins 20 having through-holes 20a having a diameter larger than the outer diameter of the pipe 30a, which is the material of the heat transfer tube 30 before being expanded, and bent portions 20b.
Then, as shown in FIG. 4 (a), the pipe 30a made of the material to be the heat transfer tube 30 is passed through the through holes 20a of the fins 20, and the plurality of fins 20 are stacked at regular intervals by the bent portions 20b. The heat transfer tube 30 is set on the material pipe 30a before expansion. In this state, a gap 16 is formed between the through hole 20a of the fin 20 and the material pipe 30a.

Thereafter, as shown in FIG. 4B, the fin 20 is elastically deformed or plastically deformed by expanding the pipe 30a so that the outer diameter of the material pipe 30a is larger than the diameter of the through hole 20a. And it joins with the heat exchanger tube 30 after a pipe expansion. At this time, adjacent fins 20 are stacked in contact with each other at the bent portion 20b. That is, the brazing material layers 22 formed on the surface of the core material 21 of the adjacent fin 20 are in contact with each other.
Thereby, the heat exchanger tube 30 and the fin 20 are joined firmly.

At this time, the distance h between the tip 20b1 of the bent portion 20b of the fin 20 and the outer surface of the heat transfer tube 30 is set to 0.1 mm or less.
The entire heat exchanger in this state is put into a heating furnace (not shown), heated, and then cooled.

  As a result, as shown in FIG. 3, the molten brazing material layer 22 is solidified as a brazing material (fillet) 15 so that the gap between the fins 20 and the heat transfer tubes 30 is completely filled, and the two are brought into close contact with each other. The joint portion can be fixed by brazing.

  According to the above configuration, the heat transfer tubes 30 are passed through the fins 20 having the through holes 20a having an inner diameter larger than the outer diameter of the pipe 30a that is the material before the expansion, so that the heat exchanger can be easily assembled. be able to.

  Further, the gap formed between the fin 20 and the heat transfer tube 30 can be completely filled with the brazing material (fillet) 15. Therefore, moisture containing a substance that induces corrosion does not enter between the heat transfer tubes 30 and the fins 20, thereby extending the corrosion life of the heat transfer tubes 30.

Further, if the fin 20 and the heat transfer tube 30 are made of different aluminum alloys so that the corrosion potential of the fin 20 is lower than the corrosion potential of the heat transfer tube 30, the fin 20 corrodes first and the heat transfer tube 30 is corroded. It is suppressed.
Therefore, the life of the heat source side heat exchanger 8 can be extended, and the heat source side heat exchanger 8 with high reliability can be obtained.

Furthermore, since the heat transfer tube 30 of the heat source side heat exchanger 8 can be made of an aluminum-based material, the weight can be reduced. In addition, since the material cost of the aluminum-based material is lower than that of the copper material, the cost of the heat source side heat exchanger 8 can be reduced.
From the above, corrosion of the aluminum heat transfer tube 30 is suppressed, and a refrigeration cycle apparatus R having a reliable and long-life heat exchanger can be provided.

<< Embodiment 2 >>
FIG. 5A is a cross-sectional view corresponding to the AA cross section of FIG. 2 at the joint portion of the heat transfer tube after being expanded with the fin of the refrigeration cycle apparatus of the second embodiment, and FIG. It is an AA cross-section equivalent view of Drawing 2 of a section in a joined part after brazing.

  In the heat source side heat exchanger 28 of the second embodiment, as shown in FIG. 5A, the fins 25 are made of an aluminum-based material, but do not form a brazing material layer on the surface. Instead, a clad tube in which a brazing filler metal layer 42 having a main component of aluminum and a melting point lower than that of the core material 41 is bonded to the surface of a core material 41 of a pipe made of an aluminum-based material is used as the heat transfer tube 40. The clad tube is a tube material obtained by rolling and joining the core material 41 and the brazing material layer 42.

Since the core material 41 and the brazing filler metal layer 42 of the clad tube are bonded by atoms, they are difficult to peel off.
Since the configuration other than the above is the same as that of the first embodiment, detailed description thereof is omitted.
The heat source side heat exchanger 28 of the cross fin tube heat exchanger of the second embodiment can also be manufactured in the same manner as in the first embodiment.

That is, the through hole 25a having a diameter larger than the outer diameter of the clad tube 40a (heat transfer tube 40), which is the material before the pipe expansion, and the fin 25 having the cylindrical bent portion 25b rising from the through hole 25a are formed.
The clad tube 40a, which is the material before the expansion of the heat transfer tube 40, is passed through the through holes 25a of the fins 25, and the clad tube 40a (heat transfer tube 40) in a state in which the plurality of fins 25 are stacked at regular intervals by the bent portions 25b. ).

  After the clad pipes 40a made of the plurality of heat transfer tubes 40 are passed through the plurality of fins 25, the heat transfer tubes 40 are expanded by a mechanical tube expansion method or the like. At this time, due to the expansion of the cladding tube 40 a, the through hole 25 a of the fin 25 is expanded by elastic deformation or plastic deformation, and the heat transfer tube 40 is joined via the through hole 25 a of the fin 25. Thereby, the heat exchanger tube 40 and the fin 25 are joined firmly. At this time, adjacent fins 25 are stacked in contact with each other at the bent portion 25b.

At this time, the distance h1 between the tip 25b1 of the fin bent portion 25b and the outer surface of the heat transfer tube 40 is set to 0.1 mm or less.
The entire heat source side heat exchanger 28 in this state is heated in a heating furnace (not shown) and then cooled.

  As a result, as shown in FIG. 5B, the molten brazing filler metal layer 42 is solidified so that the gap between the fins 25 and the heat transfer tubes 40 is completely filled without generating an unfilled space. A brazing filler metal (fillet) 15 is obtained, and both can be tightly fixed without a gap. In this case, adjacent fins 25 are stacked in contact with each other at the bent portion 25b. Since the adjacent fins 25 come into contact with each other at the bent portions 25 b, it is more difficult to form an unfilled region of the brazing filler metal 15 between the fins 25 and the heat transfer tubes 50.

In the first embodiment, since the fin 20 having the brazing filler metal layer 22 on the surface is pressed, there is a concern that the brazing filler metal 15 is reduced or peeled off. However, according to the second embodiment, since the brazing material layer 42 is provided in the clad tube 40a, the brazing material 15 is less likely to be reduced and peeled off.
Therefore, the gap formed between the fin 25 and the heat transfer tube 40 can be more reliably filled with the solidified brazing material (fillet) 15.

Further, if the fin 25 and the heat transfer tube 40 are made of different aluminum alloys so that the corrosion potential of the fin 25 is lower than the corrosion potential of the heat transfer tube 40, the fin 25 is corroded first, and the heat transfer tube 40 is corroded. It is suppressed.
In addition, also in Embodiment 2, the effect of Embodiment 1 is show | played similarly.

<< Embodiment 3 >>
FIG. 6A is a cross-sectional view corresponding to the AA cross section of FIG. 2 of the cross-sectional view of the joint portion after the brazing material layer is formed on the heat transfer tube and the fin and the heat transfer tube are brazed in the refrigeration cycle apparatus of the third embodiment. FIG. 6B is a cross-sectional view corresponding to the AA cross section of FIG. 2 in the cross-sectional view of the joint after the brazing material layer is formed on the fin and the fin and the heat transfer tube are brazed in the refrigeration cycle apparatus of the third embodiment. It is.

In the heat source side heat exchanger 38 of the third embodiment, a zinc sacrificial layer 52 is formed around the heat transfer tube 50. Thereby, corrosion of the core material tube 51 itself by corroding the zinc sacrificial layer 52 is suppressed.
The configuration other than the above is the same as that of the first embodiment, and detailed description thereof is omitted.

  In the heat source side heat exchanger 38, the plurality of fins 20 are formed with through holes 20 a through which the heat transfer tubes 50 are inserted. And the bending part 25b protrudes in one direction at the through-hole 20a, and is formed in the cylindrical shape.

  The heat transfer tube 50 passes through the through holes 20a of the plurality of fins 20. In the heat transfer tube 50, a zinc sacrificial layer 52 mainly composed of aluminum containing zinc is formed around a central core tube 51. The zinc sacrificial layer 52 is set so that the corrosion tendency increases (corrosion potential decreases) by increasing the zinc concentration as compared with the core material tube 51 of the heat transfer tube 50.

  The zinc sacrificial layer 52 is formed by spraying zinc on the surface of the core material tube 51 of the heat transfer tube 50 and then heating. For example, first, zinc melted on the surface of the core material tube 51 is sprayed and attached. Thereafter, the adhered zinc is soaked and diffused into the core material tube 51 by heat treatment.

Alternatively, an aluminum alloy having a zinc concentration higher than that of the core material tube 51 of the heat transfer tube 50 can be bonded to the core material tube 51. For example, an aluminum-based material having a high zinc concentration is joined by rolling around the core tube 51 formed of an aluminum-based material.
Since the zinc sacrificial layer 52 and the core material tube 51 formed as described above are bonded between atoms, there is no possibility of peeling.

Also in the third embodiment, the heat source side heat exchanger 38 can be manufactured in the same manner as the heat source side heat exchanger 8 of the first embodiment. That is, the material tube 50a, which is the heat transfer tube 50 before the tube expansion, is passed through the plurality of fins 20 provided with the through holes 20a and the bent portions 20b. Thereafter, the material tube 50a is expanded by a mechanical tube expansion method or the like, and the periphery of the through hole 20a of the fin 20 is elastically deformed or plastically deformed, so that the through hole 20a of the fin 20 is joined to the heat transfer tube 50. Thereby, the heat exchanger tube 50 and the fin 20 are joined firmly. At this time, when a brazing filler metal layer is formed on the surface of the heat transfer tube 50, the adjacent fins 20 are laminated in contact with each other at the bent portion 20b.
Alternatively, when a brazing filler metal layer is formed on the surface of the core material of the fin 20, the brazing filler metal layers formed on the surfaces of the adjacent fins 20 are in contact with each other. In this case, after brazing, the state shown in FIG.

At this time, the distance h2 between the tip 20b1 of the bent portion 20b of the fin 20 and the heat transfer tube surface is set to 0.1 mm or less.
The entire heat source side heat exchanger 38 in this state is heated in a heating furnace (not shown). Thereafter, by cooling, as shown in FIG. 6, the molten brazing filler metal (fillet) 15 is solidified so that the gap between the fin 20 and the heat transfer tube 50 is completely filled without any unfilled gap. To fix tightly. In this case, when a brazing filler metal layer is formed on the surface of the heat transfer tube 50, as shown in FIG. 6A, the adjacent fins 20 are in contact with each other at the bent portion 20b and laminated. Since the adjacent fins 20 come into contact with each other at the bent portion 20 b, it is more difficult to form an unfilled region of the brazing filler metal 15 between the fins 20 and the heat transfer tubes 50.

  As described above, in the prior art, the corrosion life of the heat transfer tube is extended by forming on the surface of the heat transfer tube a sacrificial anticorrosive layer containing zinc having a high corrosion tendency (low corrosion potential) on the surface of the aluminum heat transfer tube. I'm trying. However, when there is a gap between the fin and the heat transfer tube, the sacrificial anticorrosive effect of the zinc sacrificial layer may disappear early due to the intrusion of moisture containing a substance that induces corrosion.

  However, according to the third embodiment, the distance 20 between the tip 20b1 of the bent portion 20b of the fin 20 and the heat transfer tube surface is set to 0.1 mm or less, so that the fin 20 is solidified by the brazing material (fillet) 15 solidified after melting. And the heat transfer tube 50 can be reliably filled.

  Further, even when moisture containing a substance that induces corrosion enters the gap between the fin 20 and the heat transfer tube 50, the aluminum alloy having a high zinc concentration is corroded, and the corrosion of the core material tube 51 is suppressed. The life of the heat transfer tube 50 can be extended. Therefore, the life of the heat source side heat exchanger 38 can be extended and the reliability can be improved.

Further, if the fin 20 and the heat transfer tube 50 are made of different aluminum alloys so that the corrosion potential of the fin 20 is lower than the corrosion potential of the heat transfer tube 50, the fin 20 corrodes first, and the heat transfer tube 50 is corroded. It is suppressed. Therefore, the corrosion life of the heat transfer tube 50 of the heat source side heat exchanger 38 can be further extended, and the life of the heat source side heat exchanger 38 can be extended.
In addition, also in Embodiment 3, the effect of Embodiment 1 is show | played similarly.

<< Other Embodiments >>
1. In the first and second embodiments, the case where the brazing filler metal layers 22 and 42 are previously formed on the fins 20 or the heat transfer tubes 30 and 40 has been described, but the brazing filler metal layers are formed on both the fins 20 and the heat transfer tubes 30. The fins 20 and the heat transfer tubes 30 may be joined by cooling after heating. According to this, the heat transfer tube 30 is more reliably covered with the brazing material (fillet) 15 after brazing.

2. In the first to third embodiments, various configurations have been described, but each configuration may be appropriately selected and configured.

3. In the first to third embodiments, the example in which the present invention is applied to the heat source side heat exchanger 28 has been described, but the present invention may be applied to the use side heat exchanger 12.

4). The configurations described in the first to third embodiments are examples of the present invention, and various specific forms are possible within the scope of the claims.

8 Heat source side heat exchanger (heat exchanger)
12 Use-side heat exchanger (heat exchanger)
DESCRIPTION OF SYMBOLS 15 Brazing material 20, 25 Fin 20a, 25a Through-hole 22, 42 Brazing material layer 25b Bending part 25b1 End of bending part 30, 40, 50 Heat transfer pipe 41, 51 Core material pipe 52 Zinc sacrificial layer (zinc layer, aluminum alloy layer)
h, h1, h2 distance (distance between the tip of the bent part and the heat transfer tube surface)
R Refrigeration cycle equipment

Claims (8)

A heat exchanger of a refrigeration cycle apparatus comprising: a heat transfer tube through which a refrigerant flows; and a plurality of fins that are stacked on each other, and through which the heat transfer tube penetrates and has a through hole having a bent portion that rises in a cylindrical shape,
The fin and the heat transfer tube are made of aluminum or aluminum alloy,
The fin and the heat transfer tube are joined by brazing via the through hole and the bent portion, and the distance between the tip of the bent portion and the surface of the heat transfer tube is 0.1 mm or less. A heat exchanger for a refrigeration cycle apparatus. In the heat exchanger of the refrigerating cycle device according to claim 1,
The adjacent fins are in contact with each other through the bent portion. A heat exchanger of a refrigeration cycle apparatus, wherein the fins are adjacent to each other. In the heat exchanger of the refrigerating cycle device according to claim 1,
After passing the material tube of the heat transfer tube through the through hole of the fin, the outer diameter is expanded so as to be larger than the inner diameter of the through hole, and the heat transfer tube is bonded to the fin, and the bonded portion Is a brazing heat exchanger of the refrigeration cycle apparatus. The heat exchanger of the refrigeration cycle according to claim 1,
The brazing material for the brazing is formed as a brazing material layer on the surface of the fin before the brazing. The heat exchanger of the refrigeration cycle according to claim 1,
The brazing material for the brazing is formed as a brazing material layer on the surface of the heat transfer tube before the brazing. The heat exchanger of the refrigeration cycle according to claim 1,
The heat exchanger of the refrigeration cycle apparatus, wherein the fin and the heat transfer tube are made of different aluminum alloys, and the corrosion potential of the fin is lower than the corrosion potential of the heat transfer tube. The heat exchanger of the refrigeration cycle according to claim 1,
The heat transfer tube is formed with a layer containing zinc formed by thermal spraying on an outer surface of a core tube made of aluminum or aluminum alloy. The heat exchanger of the refrigeration cycle according to claim 1,
The heat transfer tube is composed of a tube in which an aluminum alloy layer having a zinc concentration higher than that of the core material tube is clad on the outer surface of the core material tube made of aluminum or aluminum alloy. Exchanger.

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