CN116235016A - Heat exchanger and method for manufacturing heat exchanger - Google Patents

Abstract

The heat exchanger is provided with: a plurality of fins arranged at intervals in the first direction; and a plurality of heat transfer pipes penetrating the plurality of fins and disposed at intervals in a second direction intersecting the first direction, the plurality of fins each having: a plate-shaped aluminum strip base material having a main surface and a side surface forming a periphery of the main surface; a hydrophilic layer provided on the main surface of the aluminum strip base material; a first corrosion-resistant layer provided between the main surface of the aluminum strip base material and the hydrophilic layer; and a second corrosion-resistant layer provided on the side surface of the aluminum strip base material.

Description

Heat exchanger and method for manufacturing heat exchanger

Technical Field

The present disclosure relates to a heat exchanger and a method for manufacturing a heat exchanger, and more particularly, to a heat exchanger having fins with a precoated film on the surfaces thereof.

Background

A heat exchanger of a conventional air conditioner includes a heat exchanger including fins and heat transfer tubes. The fins have a rectangular plate-like shape. The fins are manufactured by punching plate-shaped aluminum strips. The aluminum strip refers to an aluminum plate or an aluminum alloy plate. The aluminum strip means a material in a state before processing, and various products are manufactured by processing the aluminum strip.

One or both of a hydrophilic film and a corrosion-resistant film are pre-coated on the surface of an aluminum strip for producing fins as a pre-coating film. The hydrophilic film is provided to improve the heat exchange performance of the fin and to prevent the dew splash failure. The dew splash failure is a case where dew water is not recovered and discharged by the drain pan due to the hydrophobization of the fin surface, but is water leakage flying out from the indoor unit. The corrosion-resistant film is provided to improve the corrosion resistance of the fin.

In the production of the heat exchanger, as described above, the aluminum strip is punched in the heat exchanger forming process to form rectangular plate-like fins. Therefore, the outer peripheral ends of the fins form cut surfaces obtained by cutting the aluminum strips. The part of the cut surface is not precoated with a film, and the aluminum surface is exposed. Therefore, corrosion of the fin may start from the exposed cut surface of the aluminum surface.

For this reason, for example, patent document 1 proposes the following method: the heat exchanger is immersed in the aqueous resin coating solution, whereby the corrosion-resistant coating film is spread over the fine portions of the heat exchanger. In patent document 1, the entire part including the cut surface portion of the aluminum-exposed fin is covered with a corrosion-resistant resin by this method to improve the long-term corrosion resistance of the heat exchanger.

Patent document 1: japanese patent laid-open No. 2009-074775

However, in the method described in patent document 1, a corrosion-resistant resin is attached in addition to the cut surface. Therefore, when a hydrophilic film is applied to the surface of the fin, a corrosion-resistant resin is also attached to the hydrophilic film. As a result, there is a problem that the hydrophilicity of the hydrophilic film is deteriorated, and the heat exchange performance is lowered and the splash-back is poor.

Disclosure of Invention

The present disclosure has been made to solve the above-described problems, and an object thereof is to provide a heat exchanger and a method for manufacturing the heat exchanger, wherein: by maintaining the hydrophilicity of the fin surface unchanged and securing the corrosion resistance of the heat exchanger for a long period of time, it is possible to achieve both improvement of heat exchange performance and prevention of defects such as dew splash.

The heat exchanger of the present disclosure is provided with: a plurality of fins arranged at intervals in the first direction; and a plurality of heat transfer pipes penetrating the plurality of fins and disposed at intervals in a second direction intersecting the first direction, the plurality of fins each having: a plate-shaped aluminum strip base material having a main surface and a side surface forming a periphery of the main surface; a hydrophilic layer provided on the main surface of the aluminum strip base material; a first corrosion-resistant layer provided between the main surface of the aluminum strip base material and the hydrophilic layer; and a second corrosion-resistant layer provided on the side surface of the aluminum strip base material.

The method for manufacturing a heat exchanger of the present disclosure includes the steps of: cutting off a plate-shaped aluminum strip provided with a corrosion-resistant layer and a hydrophilic layer on the surface to form a plurality of rectangular plate-shaped fins of the same type; a step of stacking the plurality of fins in a first direction with a space therebetween such that main surfaces of the plurality of fins face each other and positions of cut surfaces of the aluminum strips of the plurality of fins are aligned; a step of coating a corrosion-resistant material on the cut surfaces of each of the plurality of laminated fins; and curing the corrosion-resistant material to form a second corrosion-resistant layer on the cut surface of each of the plurality of fins.

According to the heat exchanger and the method for manufacturing the heat exchanger of the present disclosure, the heat exchanger can be improved in heat exchange performance and prevented from being undesirably splashed or the like by maintaining the hydrophilicity of the fin surfaces unchanged and securing the corrosion resistance of the heat exchanger for a long period of time.

Drawings

Fig. 1 is a refrigerant circuit diagram showing a configuration of a refrigeration cycle apparatus 100 according to embodiment 1.

Fig. 2 is a perspective view showing an example of the structure of the indoor heat exchanger 2 according to embodiment 1.

Fig. 3 is a plan view showing an example of the structure of fins 8 of indoor heat exchanger 2 according to embodiment 1.

Fig. 4 is a partial perspective view showing the fin 8 shown in fig. 3.

Fig. 5 is a cross-sectional view A-A of fig. 3.

Fig. 6 is a B-B cross-sectional view of fig. 3.

Fig. 7 is a flowchart showing a process flow of the method for manufacturing the heat exchanger according to embodiment 1.

Fig. 8 is a schematic perspective view showing a coating process of the corrosion-resistant layer 18 in the method for manufacturing the heat exchanger according to embodiment 1.

Fig. 9 is a schematic perspective view showing a modification of the process shown in fig. 8.

Fig. 10 is a reference diagram schematically showing the fin 8 in the case where the hydrophilic layer 20 is not implemented.

Fig. 11 is a diagram showing an example of a process of applying an ultraviolet curable resin to both end portions 15bb of the protruding portion 15b in the method of manufacturing a heat exchanger according to embodiment 1.

Detailed Description

Embodiments of the heat exchanger of the present disclosure are described below with reference to the drawings. The present disclosure is not limited to the following embodiments, and various modifications can be made without departing from the spirit of the present disclosure. The present disclosure includes all combinations of combinable structures among the structures shown in the following embodiments and modifications thereof. In the drawings, the same reference numerals are given to the same or corresponding structures, and the same reference numerals are used throughout the specification. In the drawings, the relative dimensional relationship, shape, and the like of the constituent members may be different from actual ones.

Embodiment 1.

First, a refrigeration cycle apparatus in which the heat exchanger according to embodiment 1 is mounted will be described. Fig. 1 is a refrigerant circuit diagram showing a configuration of a refrigeration cycle apparatus 100 according to embodiment 1. In fig. 1, the flow of the refrigerant during the cooling operation is shown by a broken line arrow, and the flow of the refrigerant during the heating operation is shown by a solid line arrow.

As shown in fig. 1, the refrigeration cycle apparatus 100 includes a compressor 1, an indoor heat exchanger 2, an outdoor heat exchanger 3, a throttle device 4, an indoor fan 5, an outdoor fan 6, a four-way valve 7, and a control unit 40. In the refrigeration cycle apparatus 100, the compressor 1, the four-way valve 7, the indoor heat exchanger 2, the expansion device 4, and the outdoor heat exchanger 3 are connected by a refrigerant pipe 30, thereby forming a refrigerant circuit. The heat exchanger of embodiment 1 corresponds to at least one of the indoor heat exchanger 2 and the outdoor heat exchanger 3.

The compressor 1, the outdoor heat exchanger 3, the throttle device 4, the outdoor fan 6, and the four-way valve 7 are disposed in the outdoor unit. The outdoor unit is also called an outdoor unit, and is installed outdoors. The indoor heat exchanger 2 and the indoor fan 5 are disposed in the indoor unit. The indoor unit is also called an indoor unit, and is provided in an indoor space of an air-conditioning target.

The compressor 1 sucks the refrigerant flowing through the refrigerant pipe 30. The compressor 1 compresses and discharges a sucked refrigerant. The compressor 1 is, for example, a variable frequency compressor. In the case where the compressor 1 is a variable frequency compressor, the driving frequency of the motor that drives the compressor 1 may be arbitrarily changed by a driving circuit such as a variable frequency circuit, so that the capacity of the compressor 1 for delivering refrigerant per unit time may be changed. In this case, the operation of the driving circuit is controlled by the control unit 40. The refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 3 during the cooling operation and into the indoor heat exchanger 2 during the heating operation through the four-way valve 7.

The indoor heat exchanger 2 exchanges heat between the refrigerant flowing therein and the air in the room of the air-conditioning target. The indoor heat exchanger 2 functions as an evaporator during the cooling operation, and evaporates and gasifies the refrigerant. The indoor heat exchanger 2 functions as a condenser during the heating operation, and condenses and liquefies the refrigerant. The indoor heat exchanger 2 is, for example, a fin-tube heat exchanger.

The outdoor heat exchanger 3 exchanges heat between the refrigerant flowing inside and the air outside. The outdoor heat exchanger 3 functions as a condenser during the cooling operation, and condenses and liquefies the refrigerant. The outdoor heat exchanger 3 functions as an evaporator during the heating operation, and evaporates and gasifies the refrigerant. The outdoor heat exchanger 3 is, for example, a fin-tube heat exchanger.

The expansion device 4 is a pressure reducing device that reduces the pressure of the refrigerant and expands the refrigerant, and is constituted by an electronic expansion valve, for example. When the throttle device 4 is constituted by an electronic expansion valve, the opening degree of the throttle device 4 is adjusted based on the control of the control unit 40. The throttle device 4 is provided between the indoor heat exchanger 2 and the outdoor heat exchanger 3.

The indoor fan 5 has a fan motor and a blade portion. The blade portion is rotationally driven by a fan motor. The indoor fan 5 sends indoor air to the indoor heat exchanger 2. The rotational speed of the indoor fan 5 is controlled by the control unit 40.

The outdoor fan 6 includes a fan motor and a blade portion. The blade portion is rotationally driven by a fan motor. The outdoor fan 6 sends outside air to the outdoor heat exchanger 3. The rotation speed of the outdoor fan 6 is controlled by the control unit 40.

The four-way valve 7 is configured to switch states between a cooling operation and a heating operation. The four-way valve 7 is a flow path switching device that switches the flow of the refrigerant between the cooling operation and the heating operation. In the cooling operation, the four-way valve 7 is in a state shown by a broken line, and the refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 3. On the other hand, in the heating operation, the four-way valve 7 is in the state shown by the solid line, and the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2. The four-way valve 7 is switched by the control of the control unit 40.

Next, an operation of the refrigeration cycle apparatus 100 will be described.

First, a cooling operation performed by the refrigeration cycle apparatus 100 will be described. In addition, the flow of the refrigerant during the cooling operation is shown by a broken line arrow in fig. 1.

When the four-way valve 7 is switched to the cooling operation state by the control unit 40, the high-temperature and high-pressure gas refrigerant (single-phase) discharged from the compressor 1 flows into the outdoor heat exchanger 3 functioning as a condenser through the four-way valve 7. In the outdoor heat exchanger 3, heat exchange is performed between the high-temperature and high-pressure gas refrigerant flowing in and the air supplied from the outdoor fan 6. As a result, the high-temperature and high-pressure gas refrigerant is condensed to become a high-pressure liquid refrigerant (single-phase). The high-pressure liquid refrigerant sent from the outdoor heat exchanger 3 is passed through the throttle device 4 to be a low-pressure gas refrigerant and a liquid refrigerant in a two-phase state. The two-phase refrigerant flows into the indoor heat exchanger 2 functioning as an evaporator. In the indoor heat exchanger 2, heat exchange is performed between the refrigerant in the two-phase state flowing in and the air supplied from the indoor fan 5. As a result, the liquid refrigerant in the two-phase refrigerant evaporates to become a low-pressure gas refrigerant (single-phase). By this heat exchange, the room is cooled. The low-pressure gas refrigerant sent from the indoor heat exchanger 2 flows into the compressor 1 through the four-way valve 7. In the compressor 1, the low-pressure gas refrigerant is compressed to become a high-temperature high-pressure gas refrigerant, and is discharged from the compressor 1 again. The cycle is repeated as follows.

Next, a heating operation performed by the refrigeration cycle apparatus 100 will be described. In addition, the flow of the refrigerant during the heating operation is shown by solid arrows in fig. 1.

When the four-way valve 7 is switched to the heating operation state by the control unit 40, the high-temperature and high-pressure gas refrigerant (single-phase) discharged from the compressor 1 flows into the indoor heat exchanger 2 functioning as a condenser through the four-way valve 7. In the indoor heat exchanger 2, heat exchange is performed between the high-temperature and high-pressure gas refrigerant flowing in and the air supplied from the indoor fan 5. As a result, the high-temperature and high-pressure gas refrigerant is condensed to become a high-pressure liquid refrigerant (single-phase). By this heat exchange, the room is heated. The high-pressure liquid refrigerant sent from the indoor heat exchanger 2 is passed through the throttle device 4 to be a low-pressure gas refrigerant and a liquid refrigerant in a two-phase state. The two-phase refrigerant flows into the outdoor heat exchanger 3 functioning as an evaporator. In the outdoor heat exchanger 3, heat exchange is performed between the refrigerant in the two-phase state flowing in and the air supplied from the outdoor fan 6. As a result, the liquid refrigerant in the two-phase refrigerant evaporates to become a low-pressure gas refrigerant (single-phase). The low-pressure gas refrigerant sent from the outdoor heat exchanger 3 flows into the compressor 1 through the four-way valve 7. In the compressor 1, the low-pressure gas refrigerant is compressed to become a high-temperature high-pressure gas refrigerant, and is discharged from the compressor 1 again. The cycle is repeated below.

Next, the structure of the indoor heat exchanger 2 according to embodiment 1 will be described with reference to fig. 2 to 6. The structure of the outdoor heat exchanger 3 may be substantially the same as that of the indoor heat exchanger 2, and thus a description thereof will be omitted herein.

Fig. 2 is a perspective view showing an example of the structure of the indoor heat exchanger 2 according to embodiment 1. The indoor heat exchanger 2 shown in fig. 2 is a fin-tube type heat exchanger. As shown in fig. 2, the indoor heat exchanger 2 includes: a plurality of fins 8 arranged at intervals in the Y direction (first direction); and a plurality of heat transfer pipes 9 penetrating the plurality of fins 8 and arranged at intervals in the Z direction (second direction) intersecting the Y direction.

The structure of the indoor heat exchanger 2 will be described in further detail. The indoor heat exchanger 2 is composed of a plurality of fins 8, a fixing plate 32, a plurality of hairpin elbows 10, and a plurality of elbow joints 11. The plurality of hairpin bends 10 and the plurality of bent pipe joints 11 constitute a heat transfer pipe 9. The plurality of fins 8 are arranged in parallel at constant intervals in the Y direction. Therefore, the Y direction is also referred to as the stacking direction of the fins 8 or the plate thickness direction of the fins 8. The fin 8 has a plate-like shape and has two main surfaces 51 (see fig. 4) and four side surfaces. The fin 8 has a long side extending in the Z direction and a short side extending in the X direction (third direction). Here, the Z direction is, for example, the vertical direction. The X-direction and the Y-direction are, for example, horizontal directions. The X direction and the Y direction are orthogonal to each other. The X direction and the Y direction are orthogonal to the Z direction, respectively. The fixing plate 32 is disposed outside the plurality of stacked fins 8. That is, the fixing plate 32 is disposed at either end of the laminated fin 8 in the lamination direction. The fixing plate 32 has a plate-like shape. The main surface of the fixing plate 32 is arranged parallel to the main surface 51 of the fin 8. Each hairpin bend 10 has a U-shape. Therefore, each hairpin tube 10 has two straight portions 10a (see fig. 10) arranged in parallel and a single U-shaped curved portion 10b (see fig. 10) arranged between the two straight portions 10 a. The straight portion 10a of each hairpin tube 10 is arranged so as to penetrate the plurality of stacked fins 8 and the fixing plate 32. Accordingly, the straight portion 10a of the hairpin tube 10 extends in the Y direction. As shown in fig. 2, the end 10c of the hairpin tube 10, that is, the tip of the straight portion 10a on the opposite side of the curved portion 10b, protrudes from the fixing plate 32. The elbow joint 11 connects the ends 10c of the hairpin elbows 10 adjacent to each other. As shown in fig. 2, the refrigerant pipe 30 and the indoor heat exchanger 2 shown in fig. 1 are connected to each other through the distributor 13 and the plurality of refrigerant pipes 12. The refrigerant pipe 12 is distributed by the distributor 13. The dispenser 13 has a bottomed cylindrical shape. The interior of the dispenser 13 is hollow.

Fig. 3 is a plan view showing an example of the structure of fins 8 of indoor heat exchanger 2 according to embodiment 1. Fig. 4 is a partial perspective view showing the fin 8 shown in fig. 3. As shown in fig. 3 and 4, the fin 8 has a flat plate shape of an elongated rectangular shape. Therefore, the fin 8 has two main surfaces 51 and four side surfaces forming the periphery of the main surface 51. Hereinafter, the four sides are referred to as the ends 16a or 16b, respectively. As shown in fig. 3, the end 16a is an end in the short side direction, and is also referred to as a long side end. The two end portions 16a are opposed to each other and arranged parallel to each other. On the other hand, as shown in fig. 3, the end 16b is an end in the longitudinal direction, and is also called a short-side end. The two end portions 16b are opposed and arranged parallel to each other. As shown in fig. 3, corrosion resistant layers 18 are provided at the end portions 16a and 16b. Further, precoat films 50 are provided on both principal surfaces 51 of the fins 8 over the whole. The precoat film 50 has a double-layer structure composed of a hydrophilic layer and a corrosion-resistant layer. The precoating film 50 will be described later.

As described above, the fins 8 are manufactured by punching out plate-shaped aluminum strips. Therefore, the end portions 16a and 16b constituting the side surfaces of the fin 8 include cut surfaces formed when the aluminum strip is cut. Therefore, the aluminum bar base material 17 (see fig. 5 and 6) is exposed without the precoating film 50 at the end portions 16a and 16b. Therefore, in embodiment 1, in order to prevent corrosion from starting from the end portions 16a and 16b, the end portions 16a and 16b are provided with the corrosion-resistant layer 18. The corrosion resistant layer 18 is configured to cover the ends 16a and 16b of the fins 8. The corrosion resistant layer 18 is implemented as a pre-coat film 50 that covers only the ends 16a and 16b of the fins 8, and is not applied to the main face 51 of the fins 8.

As shown in fig. 3 and 4, a hairpin bent tube insertion hole 14 is formed in the fin 8. The hairpin bent tube insertion hole 14 is a through hole penetrating the plate thickness of the fin 8. The hairpin bent-tube insertion holes 14 are arranged in a single row or a plurality of rows at constant intervals along the longitudinal direction of the fin 8. In fig. 3 and 4, the hairpin tube insertion holes 14 are shown arranged in a single row for simplicity of the drawing, but in the case of the indoor heat exchanger 2 in a plurality of rows, the hairpin tube insertion holes 14 are arranged in a plurality of rows, as shown in fig. 2. As shown in fig. 4, a horn-shaped fin collar 14a is formed on the outer periphery of the hairpin elbow insertion hole 14. The fin collar 14a is formed by, for example, cutting. Specifically, the fin collar 14a is formed by digging the main surface of the fin 8 into a circular shape and bulging the circumferential portion. The straight portion 10a of the hairpin tube 10 is inserted into the hairpin tube insertion hole 14 (see fig. 10). Therefore, the longitudinal direction of the fin 8 intersects the axial direction of the straight portion 10a of the hairpin tube 10 perpendicularly or substantially perpendicularly.

As shown in fig. 3 and 4, a louver 15 may be formed on the surface of the fin 8 as a heat transfer promoting portion. For example, a plurality of rows of louver plates 15 are arranged between adjacent hairpin tube insertion holes 14. The louver 15 is formed by, for example, cutting and machining. Specifically, first, two slits 15a are formed in parallel on the main surface 51 of the fin 8. The slit 15a penetrates the plate thickness of the fin 8. Next, the rectangular portion 15b between the two slits 15a is raised by bending processing so as to protrude from the surface of the fin 8. Through the above steps, the louver 15 is formed. Hereinafter, the raised portion 15b is referred to as a protrusion 15b of the shutter plate 15. When the louver 15 is provided on the fin 8, a part of the air flowing along the main surface 51 of the fin 8 passes through the louver 15. That is, air flows from the slit 15a of the louver 15 through the lower portion of the protruding portion 15b. Therefore, heat transfer of the indoor heat exchanger 2 is promoted.

Fig. 5 is a cross-sectional view A-A of fig. 3. Further, fig. 6 is a B-B sectional view of fig. 3. As shown in fig. 5 and 6, in the fin 8, corrosion-resistant layers 19 are provided on the upper and lower surfaces of the rectangular plate-shaped aluminum strip base material 17. Further, a hydrophilic layer 20 is provided on the upper surface of the upper corrosion-resistant layer 19. Similarly, a hydrophilic layer 20 is provided on the lower surface of the lower corrosion-resistant layer 19. Therefore, as shown in fig. 5 and 6, the fin 8 is laminated with the hydrophilic layer 20, the corrosion-resistant layer 19, the aluminum strip base material 17, the corrosion-resistant layer 19, and the hydrophilic layer 20 in this order in the Y direction. Therefore, the upper and lower surfaces of the aluminum strip base material 17 are covered with the corrosion-resistant layer 19, thereby preventing corrosion. Further, a hydrophilic layer 20 is provided on the outer side of the corrosion-resistant layer 19. The hydrophilic layer 20 improves the heat exchange performance of the fin 8 and prevents the dew splash failure.

As shown in fig. 5, the aluminum strip base material 17 is exposed at the end portion 16b. That is, the aluminum strip base material 17 is exposed to the outside. Therefore, in embodiment 1, as shown in fig. 3 and 6, the end portion 16b is provided with the corrosion-resistant layer 18. This can prevent corrosion from the end portion 16b. Further, the corrosion-resistant layer 18 may be provided only on the side surface of the aluminum strip base material 17, but as shown in fig. 6, it is preferable that the end portion 16b is provided over the side surface of the aluminum strip base material 17, the side surface of the corrosion-resistant layer 19, and the side surface of the hydrophilic layer 20.

Similarly, as shown in fig. 6, the aluminum strip base material 17 is exposed at the end portion 16a. Therefore, in embodiment 1, as shown in fig. 3 and 5, the end portion 16a is provided with the corrosion-resistant layer 18. This can prevent corrosion from the end portion 16a. Further, the corrosion-resistant layer 18 may be provided only on the side surface of the aluminum strip base material 17, but as shown in fig. 5, it is preferable that the end portion 16a is provided over the side surface of the aluminum strip base material 17, the side surface of the corrosion-resistant layer 19, and the side surface of the hydrophilic layer 20.

In this way, since the fin 8 of embodiment 1 is formed by cutting the aluminum strip, the end portions 16a and 16b become cut surfaces of the aluminum strip base material 17 exposed in the state after the cutting process. Therefore, in embodiment 1, the corrosion-resistant layer 18 is provided at the end portions 16a and 16b including the cut surface where the aluminum strip base material 17 is exposed. A double layer composed of the corrosion-resistant layer 19 and the hydrophilic layer 20 is formed as the precoat film 50 on the main surface 51 of the fin 8. Thus, the main surface 51 of the fin 8 can be prevented from corroding while maintaining hydrophilicity.

Here, the function of the hydrophilic layer 20 will be described. The hydrophilic layer 20 is a film having a function of improving the wet spreading characteristics of water on the main surface 51 of the fin 8. Hydrophilic layer 20 has a contact angle of, for example, 50 ° or less, preferably 30 ° or less, with respect to water. Because of its nature, hydrophilic layer 20 has a good affinity for water, and therefore moisture readily permeates hydrophilic layer 20. Therefore, dew water adhering to the main surface 51 of the fin 8 flows along the hydrophilic layer 20 toward the lower side in the Z direction in fig. 2, is collected by a drain pan (not shown) disposed at the lower portion of the fin 8, and is discharged from the drain pan. Therefore, occurrence of dew splash defect in which dew condensation water flies out to the outside can be prevented. Further, by providing the hydrophilic layer 20, dew condensation water adhering to the surface of the fin 8 can be rapidly discharged, and therefore, the heat exchange efficiency of the fin 8 can be improved. This will be described below.

In the case where the hydrophilic layer 20 is not provided to the fins 8, the heat exchange performance of the fins 8 is degraded due to dew adhering to the fins 8. In particular, when a bridge of dew condensation water is formed between adjacent fins 8, the heat exchange performance of the fins 8 is greatly reduced. Fig. 10 is a reference diagram schematically showing the fin 8 in the case where the hydrophilic layer 20 is not implemented. In the case where the fins 8 are not provided with the hydrophilic layer 20, as shown in fig. 10, dew condensation water adhering to adjacent fins 8 is linked to each other to form a bridge 60 of dew condensation water. If the bridge 60 of dew condensation water is formed, the ventilation resistance increases, and air is less likely to flow between the fins 8. As a result, the load of the indoor heat exchanger 2 increases, and the heat exchange performance also decreases. On the other hand, in embodiment 1, since the hydrophilic layer 20 is provided on the fin 8, dew condensation water is easily discharged, and formation of the bridge 60 of dew condensation water can be prevented. As a result, the ventilation resistance is smaller than in the case of the reference diagram of fig. 10, and therefore, an increase in the load of the indoor heat exchanger 2 can be suppressed, and a decrease in the heat exchange performance can be prevented.

However, if moisture that has permeated the hydrophilic layer 20 adheres to the aluminum strip base material 17, there is a possibility that corrosion of the aluminum strip base material 17 starts. Therefore, in embodiment 1, the corrosion-resistant layer 19 is provided between the hydrophilic layer 20 and the aluminum strip base material 17. Since the corrosion-resistant layer 19 does not transmit moisture, the moisture transmitted through the hydrophilic layer 20 can be prevented from penetrating toward the aluminum strip base material 17.

The function of the corrosion-resistant layer 19 will be described in further detail. The corrosion-resistant layer 19 is a film having a function of protecting the aluminum strip base material 17 from water, and has a function of preventing permeation of water. The corrosion-resistant layer 19 is made of a material such as epoxy, acrylic, or polyurethane. Since the corrosion-resistant layer 19 has a waterproof function, it has a poor affinity for water as compared with the hydrophilic layer 20, and the contact angle with water is, for example, 40 ° or more in many cases. Depending on the function, the corrosion-resistant layer 19 may be called a water-repellent layer, an anticorrosive layer, or the like.

As described above, in the fin 8 of embodiment 1, as shown in fig. 5 and 6, the corrosion-resistant layer 18 is provided at the end portions 16a and 16b of the fin 8, and the hydrophilic layer 20 is provided on the outermost surface of the main surface 51 of the fin 8. A corrosion-resistant layer 19 is provided between the hydrophilic layer 20 and the aluminum strip base material 17. According to this structure, the main surface 51 of the fin 8 contributing to the heat exchange performance has hydrophilicity and corrosion resistance, while the end portions 16a and 16b of the fin 8 not contributing to the heat exchange performance have corrosion resistance. That is, in embodiment 1, the fins 8 can prevent corrosion from the cut surfaces of the aluminum strips while maintaining hydrophilicity that improves heat exchange performance.

In embodiment 1, the cut surfaces of the fins 8 are covered with the corrosion-resistant layer 18, so that elution of aluminum ions from the cut surfaces can be prevented. As a result, the hydrophobization of the main surface 51 of the fin 8 can be suppressed. Therefore, in embodiment 1, even when the indoor unit is installed in a hydrophobized environment, the occurrence of splash-up due to the hydrophobization of the indoor heat exchanger 2 is effectively suppressed.

In the above description, the structure of the indoor heat exchanger 2 has been described, but the outdoor heat exchanger 3 may have the same structure as the indoor heat exchanger 2. When the outdoor unit is installed in a severe corrosion environment such as a salt region, it is considered that corrosion progresses from the cut surfaces of the fins 8. As a result, if the precoat film 50 applied to the fins 8 disappears or corrodes, clogging between the fins 8 or falling-off of the fins 8 may occur. In this case, the heat exchange performance of the outdoor heat exchanger 3 is degraded. In embodiment 1, the cut surfaces of the fins 8 are covered with the corrosion-resistant layer 18, so that even when the outdoor unit is installed in a severe corrosive environment such as a salt region, corrosion from the cut surfaces of the fins 8 can be prevented. As a result, the heat exchange performance of the outdoor heat exchanger 3 can be prevented from being degraded for a long period of time.

Next, a method for manufacturing the heat exchanger according to embodiment 1 will be described with reference to fig. 2, 7, and 8. Fig. 7 is a flowchart showing a process flow of the method for manufacturing the heat exchanger according to embodiment 1. Fig. 8 is a schematic perspective view showing a coating process of the corrosion-resistant layer 18 in the method for manufacturing the heat exchanger according to embodiment 1. Fig. 8 shows an example of the coating step, but is not limited to this, as long as the method is capable of coating the corrosion-resistant layer 18 only on the cut surface of the fin 8. Since the indoor heat exchanger 2 and the outdoor heat exchanger 3 have substantially the same structure, a method for manufacturing the indoor heat exchanger 2 will be described herein, and a method for manufacturing the outdoor heat exchanger 3 will not be described herein.

Before describing a method of manufacturing the heat exchanger, a structure of an apparatus for applying a corrosion-resistant material for forming the corrosion-resistant layer 18 to the end portions 16a of the fins 8 will be described with reference to fig. 8. As shown in fig. 8, the apparatus has two roll coaters 21, two ultraviolet lamps 22, and a box-shaped shield case 23. The device may have a first motor 41 and a second motor 42 as needed. The first motor 41 rotationally drives the roll coater 21. The second motor 42 moves the laminated fins 8 in the direction of arrow a. The operations of the first motor 41 and the second motor 42 are controlled by a control device, not shown.

The two roll coaters 21 have a cylindrical shape. The two roll coaters 21 are each configured to be rotatable around a rotation axis 21a provided at the center in the radial direction. The rotation shaft 21a extends in the Y direction. The two roll coaters 21 are disposed so as to face each other with a first gap therebetween. The width of the first gap is adjusted in accordance with the length of the short-side end 16b of the fin 8. Therefore, when the laminated fin 8 is disposed between the two roll coaters 21, the circumferential surface of the roll coater 21 is in contact with the long side end 16a of the fin 8. The surfaces of the two roll coaters 21 in the circumferential direction are impregnated with a corrosion-resistant material.

The two ultraviolet lamps 22 are disposed so as to face each other with the second gap therebetween. The two ultraviolet lamps 22 radiate ultraviolet light toward the long-side end 16a of the fin 8. Therefore, the radiation surfaces of the ultraviolet lamps 22 that emit the ultraviolet light are disposed so as to face each other with the second gap therebetween. The second void has a width greater than the first void. Therefore, when the laminated fins 8 are arranged between the two ultraviolet lamps 22, the radiation surface of the ultraviolet lamp 22 does not contact the long-side end 16a of the fin 8. The two ultraviolet lamps 22 radiate ultraviolet light toward the long-side end 16a of the fin 8.

The two ultraviolet lamps 22 are accommodated in a box-shaped shielding case 23. The shielding case 23 has light shielding properties, and shields the ultraviolet light emitted from the two ultraviolet lamps 22 from leaking to the outside.

Next, a method of manufacturing the heat exchanger will be described. As shown in fig. 7, first, in step S1, hairpin bent tube insertion holes 14 and louvers 15 are formed in the aluminum strip on which the precoated film 50 is applied. Thereafter, the aluminum strip is cut so as to have the shape of the fin 8. Thereby, a plurality of rectangular plate-like fins 8 are formed. The order of the steps performed in step S1 is not particularly limited. Therefore, for example, after the aluminum strip is cut so as to form the fin 8, the hairpin bent tube insertion hole 14 and the louver 15 may be formed.

Next, in step S2, a plurality of fins 8 are laminated. When stacking the plurality of fins 8, the main surfaces 51 of the fins 8 are arranged at intervals so as to face each other. Thus, as shown in fig. 8, the positions of the end portions 16a arranged as the plurality of fins 8 are aligned in one example.

Next, in step S3, as shown in fig. 8, an ultraviolet curable resin as a corrosion resistant material is applied to the end portions 16a of the laminated fins 8 using a roll coater 21. The roll coater 21 is rotatably provided. The roll coaters 21 may be disposed only on one side of the fin 8, but as shown in fig. 8, by providing the roll coaters 21 on both sides of the fin 8, the ultraviolet curable resin can be applied to both end portions 16a of the fin 8 at a time. In this case, the ultraviolet curable resin can be applied to the both end portions 16a of the fin 8 by inserting the laminated fin 8 in the direction of arrow a between the two roll coaters 21 and moving them. Further, the roll coater 21 is rotationally driven by a first motor 41. The stacked fins 8 are moved in the direction of arrow a by the second motor 42.

Next, in step S4, as shown in fig. 8, the ultraviolet light emitted from the ultraviolet lamp 22 is irradiated to the ultraviolet curing resin to cure the ultraviolet curing resin. The ultraviolet curable resin after curing becomes the corrosion resistant layer 18. At this time, as shown in fig. 8, by providing the ultraviolet lamps 22 on both sides of the fin 8, the ultraviolet curable resin applied to both end portions 16a of the fin 8 can be cured at a time. In this way, the corrosion-resistant layer 18 can be fixed to the end 16a of the fin 8. In the step S4, it is preferable that the ultraviolet lamp 22 is surrounded by the ultraviolet-ray-opaque shield case 23 as shown in fig. 8 so that the ultraviolet-ray-curable resin on the roll coater 21 is not cured by the ultraviolet light emitted from the ultraviolet lamp 22. In the example of fig. 8, a box-shaped shield case 23 is shown, but the shape of the shield case 23 is not particularly limited. In step S4, the ultraviolet lamp 22 is fixed, and the fin 8 is moved in the direction of arrow a, whereby the entire end 16a of the fin 8 is irradiated with ultraviolet light. Alternatively, the ultraviolet lamp 22 may be moved in the direction of arrow a to irradiate the entire end 16a of the fin 8 with ultraviolet light. In this case, the shield case 23 may be moved together with the ultraviolet lamp 22 in synchronization with the ultraviolet lamp 22.

In step S5, a bending process is performed to bend the hairpin bent tube 10 into a U-shape. The step S5 may be performed in parallel with the steps S1 to S4, but the timing of performing the step S5 is not particularly limited. That is, step S5 may be performed after steps S1 to S4, or steps S1 to S4 may be performed after step S5 is performed.

Next, in step S6, the fixing plate 32 is provided to the laminated fins 8, and the hairpin bent tube 10 bent into a hairpin shape is inserted into the hairpin bent tube insertion hole 14 of the fins 8.

Next, in step S7, the hairpin tube 10 is expanded by a tube expansion process using a tool such as a mandrel, for example, to improve the adhesion between the fins 8 and the hairpin tube 10. The mandrel is a tool provided with a pipe expanding ball at the tip of the rod.

Next, in step S8, the U-shaped elbow joint 11 is attached to the end portion 10c of the hairpin elbow 10.

Next, in step S9, the end 10c of the hairpin elbow 10 is joined to the elbow joint 11 by brazing.

Fig. 9 is a schematic perspective view showing a modification of the process shown in fig. 8. Fig. 8 shows a case where only the long-side end 16a of the fin 8 is coated with an ultraviolet curable resin and cured. However, the ultraviolet curable resin is preferably applied to the short-side end 16b of the fin 8 to form the corrosion-resistant layer 18. Therefore, as shown in fig. 9, a second roll coater 26 for applying ultraviolet curable resin to the short-side end 16b of the fin 8 may be further provided to the structure of the apparatus shown in fig. 8. In fig. 9, for simplification of the drawing, the case where the second roll coater 26 is provided only on one side of the short side of the fin 8 is shown, but the second roll coater 26 may be provided on both sides of the short side of the fin 8. In this case, the ultraviolet curable resin can be applied to the both short-side end portions 16b of the fin 8 at a time. The corrosion-resistant layer 18 may be provided only at the end 16a on the long side of the fin 8, but in the case where the corrosion-resistant layer 18 is provided at both the end 16a and the end 16b of the fin 8, the effects of preventing aluminum corrosion and preventing splash-back can be further improved. In addition, the second roll coater 26 has a cylindrical shape. The second roll coater 26 is configured to be rotatable around a rotation axis 26a provided at the center in the radial direction. The rotation shaft 26a extends in the X direction. Further, the second roll coater 26 is provided so as to be movable in the direction of arrow B. The second roll coater 26 is rotated and moved in the direction of arrow B, whereby the end 16B of the fin 8 can be coated with the ultraviolet curable resin. The coated ultraviolet curable resin is cured by irradiation with ultraviolet light emitted from the ultraviolet lamp 22. Further, the second roll coater 26 is rotationally driven by a third motor 43 and is moved in the direction of arrow B by a fourth motor 44.

As described above using fig. 3 and 4, the fin 8 is provided with the hairpin tube insertion hole 14 and the louver 15. Since the hairpin elbow insertion hole 14 and the louver 15 are formed by cutting, the end portions of the fin collar 14a of the hairpin elbow insertion hole 14 and the end portions of the protruding portion 15b of the louver 15 become cut surfaces where the aluminum strip base material 17 is exposed. Therefore, the corrosion-resistant layer 18 may be formed also on these cut surfaces. In this case, the corrosion prevention effect of the aluminum strip base material 17 can be further improved.

Fig. 11 is a diagram showing an example of a process of applying an ultraviolet curable resin to both end portions 15bb of the protruding portion 15b in the method of manufacturing a heat exchanger according to embodiment 1. The both end portions 15bb of the protruding portion 15b are end portions of the protruding portion 15b on the slit 15a side. Fig. 11 is a side view of the fin 8 as viewed in the direction of arrow C of fig. 4. As shown in fig. 11, a plurality of protruding portions 15b of the louver 15 are arranged in a row on the fin 8. Props 24 such as brushes are arranged in accordance with the positions of both end portions 15bb of the protruding portion 15b. Prop 24 is a prop having a plurality of hairs attached to the tip of a shank made of metal, wood, plastic, or the like. The ultraviolet curable resin is applied to both end portions 15bb of the protruding portion 15b by the prop 24. The coated ultraviolet curable resin is cured by irradiation of ultraviolet light. Each prop 24 is fixed to a common drive rod 25. By moving the driving lever 25 in the Y direction, the position of the prop 24 is adjusted for the height position of the both end portions 15bb of the protruding portion 15b, and the ultraviolet curable resin is applied to the both end portions 15bb of the protruding portion 15b. As shown in fig. 4, since the louvers 15 are arranged at a constant interval in the Z direction in the fin 8, when the ultraviolet curable resin is applied to the both end portions 15bb of the protruding portion 15b, the prop 24 is moved in the Z direction or the fin 8 is moved in the Z direction. Thus, the ultraviolet curable resin can be sequentially applied to the both end portions 15bb of the protruding portions 15b of the louver 15 arranged in the Z direction. In addition, in the portion of the fin collar 14a, when the ultraviolet curable resin is not applied and the skip is desired, the driving rod 25 is moved upward in the Y direction. In this way, by using the common driving lever 25, the ultraviolet curable resin can be applied to the plurality of protruding portions 15b at a time. Further, the driving lever 25 is driven by a motor or the like. In this case, the prop 24 is exemplified by a brush, but is not limited to this case. Prop 24 may also be another prop such as a brush, roller, doctor blade, etc. Alternatively, the props 24 may be any props other than those described above, as long as the ultraviolet curable resin can be applied to the both end portions 15bb of the protruding portion 15b. Further, the driving lever 25 is driven by a fifth motor 45. The applied ultraviolet curable resin is cured by irradiation with ultraviolet light by the ultraviolet lamp 22, and becomes the corrosion resistant layer 27 as the third corrosion resistant layer.

In this way, in the fin 8, in addition to the corrosion-resistant layer 19 as the first corrosion-resistant layer and the corrosion-resistant layer 18 as the second corrosion-resistant layer, the cut surface formed at the time of processing the hairpin elbow insertion hole 14 or the louver 15 is also formed with the corrosion-resistant layer 27 as the third corrosion-resistant layer, whereby the effects of preventing aluminum corrosion and preventing dew-splash defects can be further improved.

Further, by using an ultraviolet curable resin for the corrosion- resistant layers 18 and 27, the corrosion- resistant layers 18 and 27 can be formed without damaging the precoat film 50. When a baking type paint is used as the corrosion-resistant layer, the precoat film 50 may deteriorate due to heat load during baking, thereby deteriorating the hydrophilic performance and corrosion resistance, or causing the precoat film 50 to burn off (phenomenon or disappearance). Therefore, in embodiment 1, by using the ultraviolet curable resin for the corrosion- resistant layers 18 and 27, the corrosion- resistant layers 18 and 27 can be formed on the cut surfaces of the aluminum strip without damaging the precoat film 50.

As described above, in embodiment 1, the fin 8 has: a plate-shaped aluminum strip base material 17 having a main surface and side surfaces; a hydrophilic layer 20 provided on the main surface of the aluminum strip base material 17; and a corrosion-resistant layer 19 provided between the main surface of the aluminum strip base material 17 and the hydrophilic layer 20. The fin 8 further includes a corrosion-resistant layer 18 provided on the side surface of the aluminum strip base material 17. By providing the hydrophilic layer 20, the hydrophilicity of the fin 8 can be maintained. Further, by providing the corrosion- resistant layers 19 and 18, the heat exchanger can be ensured to have long-term corrosion resistance. Therefore, the heat exchanger can have both of the heat exchange performance and the splash prevention.

In embodiment 1, as shown in fig. 8, the ultraviolet curable resin is applied by using a roll coater 21 in a state where the fins 8 are laminated. Since the fins 8 are laminated, the end portions 16a of the plurality of fins 8 are aligned, and therefore the ultraviolet curable resin can be easily applied to the end portions 16a of the plurality of fins 8 at a time.

Description of the reference numerals

1 … compressor; 2 … indoor heat exchanger; 3 … outdoor heat exchanger; 4 … throttle device; 5 … indoor fan; 6 … outdoor fan; 7 … four-way valve; 8 … fins; 9 … heat transfer tubes; 10 … hairpin elbows; 10a … straight portions; 10b … curve portion; 10c … end; 11 … elbow joint; 12 … refrigerant piping; 13 … dispenser; 14 … hairpin elbow insertion hole; 14a … fin collar; 15 … shutter plates; 15a … slit; 15b … tab; 15bb … ends; 16a … end; 16b … end; 17 … aluminum strip base material; 18 … corrosion-resistant layer (second corrosion-resistant layer); 19 … corrosion-resistant layer (first corrosion-resistant layer); 20 … hydrophilic layer; 21 … roll coater; 21a … rotation axis; 22 … ultraviolet lamp; 23 … shield casing; 24 … props; 25 … drive rod; 26 … second roll coater; 26a … rotation axis; 27 … corrosion-resistant layer (third corrosion-resistant layer); 30 … refrigerant piping; 32 … fixing plate; 40 … control part; 41 … first motor; 42 … second motor; 43 … third motor; 44 … fourth motor; 45 … fifth motor; 50 … precoating film; 51 … major face; a 60 … bridge; 100 … refrigeration cycle device.

Claims (8)

1. A heat exchanger, comprising:

a plurality of fins arranged at intervals in the first direction; and

a plurality of heat transfer pipes penetrating the plurality of fins and arranged at intervals in a second direction intersecting the first direction,

the plurality of fins each have:

a plate-shaped aluminum strip base material having a main surface and a side surface forming a periphery of the main surface;

a hydrophilic layer provided on the main surface of the aluminum strip base material;

a first corrosion-resistant layer provided between the main surface of the aluminum strip base material and the hydrophilic layer; and

and a second corrosion-resistant layer provided on the side surface of the aluminum strip base material.

2. A heat exchanger according to claim 1 wherein,

the second corrosion-resistant layer is ultraviolet curing resin.

3. A heat exchanger according to claim 1 or 2, wherein,

the second corrosion-resistant layer is provided on the side surface of the hydrophilic layer and the side surface of the first corrosion-resistant layer in addition to the side surface of the aluminum strip base material.

4. A heat exchanger according to any one of claims 1 to 3 wherein,

the plurality of fins each have a louver provided on the main surface,

the shutter plate has:

two slits formed through the plate thickness of the fin;

a protrusion formed by swelling a portion between the two slits; and

and a third corrosion-resistant layer provided at the slit-side end of the protruding portion.

5. A method for manufacturing a heat exchanger, comprising the steps of:

cutting off a plate-shaped aluminum strip provided with a corrosion-resistant layer and a hydrophilic layer on the surface to form a plurality of rectangular plate-shaped fins of the same type;

a step of stacking the plurality of fins in a first direction with a space therebetween such that main surfaces of the plurality of fins face each other and positions of cut surfaces of the aluminum strips of the plurality of fins are aligned;

a step of coating a corrosion-resistant material on the cut surfaces of each of the plurality of laminated fins; and

and curing the corrosion-resistant material to form a second corrosion-resistant layer on the cut surface of each of the plurality of fins.

6. The method of manufacturing a heat exchanger according to claim 5, wherein,

the cut surfaces of the long sides of the plurality of stacked fins extend in a second direction intersecting the first direction, the cut surfaces of the long sides are arranged in the first direction,

in the step of applying the corrosion-resistant material, the corrosion-resistant material is applied to the cut surfaces of the long sides of the plurality of stacked fins using a roll coater having a rotation shaft extending in the first direction and provided rotatably.

7. A method for manufacturing a heat exchanger according to claim 5 or 6, wherein,

the short-side cut surfaces of the plurality of stacked fins extend in a third direction intersecting the first direction, the short-side cut surfaces being arranged in the first direction,

in the step of coating the corrosion-resistant material, a second roll coater having a rotation axis extending in the third direction and rotatably provided is used to coat the cut surfaces of the short sides of the laminated fins with the corrosion-resistant material.

8. The method for manufacturing a heat exchanger according to any one of claims 5 to 7, wherein,

the corrosion-resistant material is ultraviolet curing resin,

in the step of forming the second corrosion-resistant layer, ultraviolet light is irradiated to the corrosion-resistant material applied to the cut surfaces of each of the plurality of fins, so that the corrosion-resistant material is cured.

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