JPH09303989A - Aluminum heat exchanger having excellent corrosion resistance and method of manufacturing the same - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: For a heat exchange tube made of a molded product of an aluminum plate, regardless of whether it is in contact with fins or not, the whole tube has improved corrosion resistance and excellent corrosion resistance. An aluminum heat exchanger and a method for manufacturing the same are provided. SOLUTION: The heat exchange tubes 1 and 101 are made of a molded product of an aluminum plate material, and a plurality of the heat exchange tubes are arranged in parallel with each other via aluminum fins 2 and the tubes 1 and 101 are arranged. And fin 2
In the heat exchanger where and are joined, the heat exchange tube
An aluminum plate material having a Zn layer 15b on at least one surface is formed to have the Zn layer on the outer surface, the tube and the fin are joined via the Zn layer, and the corrosion protection layer on the surface of the tube is formed by the Zn layer. Are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum heat exchanger used for air conditioners such as condensers, evaporators and radiators for car air conditioners, and for various other purposes. The present invention relates to a heat exchanger and a manufacturing method thereof.

[0002] In this specification, the term aluminum is used to include both aluminum and aluminum alloys.

[0003]

2. Description of the Related Art In this type of aluminum heat exchanger, generally, a plurality of aluminum heat exchange tubes are arranged in parallel with each other via aluminum fins to form a core. In order to withstand use in a corrosive environment, it may be configured to have corrosion resistance.

According to the conventional anti-corrosion concept of such an aluminum heat exchanger, the fin is made of aluminum to which an element having a sacrificial corrosion effect such as Sn, Zn, In is added, and the fin is sacrificed by the sacrificial corrosion action of the tube. It was to secure corrosion resistance.

[0005]

However, in such a structure, since the fin and the tube are partially joined, a sufficient tube anticorrosion effect can be exerted at the joined portion, but the fin and the tube cannot be directly connected to each other. Corrosion protection was insufficient for the parts that were not in contact. In particular, recently, in order to make it possible to further reduce the thickness of the heat exchange tube, it has been proposed to replace the extruded shape with a tube and use a molded product of an aluminum plate material. However, there is a problem of early corrosion.

The present invention has been made in view of such circumstances, and is intended for a heat exchange tube made of a molded product of an aluminum plate material regardless of a contact portion with a fin and a non-contact portion. It is an object of the present invention to provide an aluminum heat exchanger having excellent corrosion resistance, in which the corrosion resistance of the entire tube is improved, and a manufacturing method thereof.

[0007]

In order to achieve the above object, in the heat exchanger according to the present invention, the heat exchange tube is made of a molded aluminum plate material, and a plurality of the heat exchange tubes are connected to each other. In the heat exchanger in which the fins are arranged in parallel via aluminum fins, and the tubes and the fins are joined together, the heat exchange tube has an aluminum plate material having a Zn layer on at least one surface, and the Zn layer is formed on the outer surface. Formed in what is present, the Zn
The tube and the fin are joined through the layer,
The Zn layer forms an anticorrosion layer on the surface of the tube. Further, the heat exchanger manufacturing method according to the present invention includes a plurality of heat exchange tubes formed on an outer surface of the aluminum plate member having a Zn layer on at least one surface thereof. After arranging them in parallel through the fins and assembling them into a core, applying flux to the core and then heating it to melt the Zn layer on the outer surface of the heat exchange tube to bond the heat exchange tube and the fin. It is characterized by.

Therefore, according to the heat exchanger according to the present invention and the heat exchanger manufactured according to the present invention, the Zn anticorrosion layer can be formed on the entire surface of the tube, and the Zn contact layer and the non-contact portion with the fin can be secured. Therefore, the corrosion resistance of the entire tube can be improved. Therefore, for example, a heat exchange tube composed of a main body having a comb-shaped cross section having outer walls in the middle in the width direction at both ends in the width direction, and a lid body covering the front end side of the reinforcing wall of the main body and joined to the main body. As described above, even when the tube is a thin product made of a molded aluminum plate material, its corrosion resistance can be further improved.

[0009]

1 shows an embodiment of the present invention, in which the present invention is applied to a condenser for an air conditioner made of aluminum used for a car air conditioner or the like. This heat exchanger comprises a flat heat exchange tube (1) arranged in parallel in a vertical direction and an adjacent tube (1).
A core is formed by the corrugated fins (2) interposed between (1), and both ends of each tube (1) are communicatively connected to a pair of left and right headers (3) and (4).
In FIG. 1, (5) and (5) are side plates arranged outside the upper and lower outermost corrugated fins,
(6) is a partition plate that partitions the headers (3) and (4) in the longitudinal direction so that the refrigerant passage constituted by the tube group serves as a meandering passage, (7) is a refrigerant inlet pipe, and (8) is a refrigerant outlet. It is a tube.

As shown in FIG. 2 and FIG. 3, the heat exchange tube (1) has outer walls (uprightly rising from the flat plate portion (11) at both ends in the width direction of the flat plate portion (11). 12), and a main body (1) having a comb-shaped cross section having a plurality of reinforcing walls (13) vertically rising at intervals in the widthwise middle portion of the flat plate portion (11).
4) and a lid body (15) for closing the main body (14) on the side opposite to the flat plate portion (11) with the outer wall (12) and the reinforcing wall (13) interposed therebetween. And the body (14)
Wedge-shaped step (1) provided on the inner surface upper part of the outer wall (12) of the
6), the both ends in the width direction of the lid body (15) formed in the corresponding shape are fitted and temporarily assembled, and the outer wall (12) and the reinforcing wall (1
The end surface of 3) and the inner surface of the lid body (15) are brazed. Body (14) with a comb-shaped cross section of this tube (1)
Is manufactured by roll-forming a sheet-shaped aluminum plate material, and the lid body (15) is also manufactured by an aluminum sheet. in this way,
Since the main body (14) and the lid (15) are made of aluminum plate material, the wall thickness can be reduced.

The corrugated fins (2) are formed by forming a sheet-shaped aluminum bare material having a width substantially the same as that of the tube (1) into a corrugated shape and cutting and raising the louver.

The headers (3) and (4) are formed by forming an aluminum brazing sheet having a brazing material layer on both front and back surfaces into a pipe having a circular cross section, and a tube insertion hole is formed on the peripheral surface in the longitudinal direction. Both ends of each tube (1) are inserted and connected to the tube insertion hole while being formed along the interval.

Thus, on the outer surface of the tube (1),
An anticorrosion layer containing Zn is coated. Zn in the anticorrosion layer plays a role of anticorrosion of the tube by its sacrificial corrosion action. For this purpose, the anticorrosion layer may be entirely formed of Zn, or a part of Zn may be contained. However, if the Zn content is too small, the anticorrosion effect becomes poor. 1.2 wt%
It is desirable to secure the above.

The Zn-containing anticorrosion layer on the surface of the heat exchange tube (1) is formed as follows.

That is, as shown in FIGS. 2 and 3, using a plate material in which the Zn layers (14b) and (15b) are clad on at least one surface of the aluminum core materials (14a) and (15a), Z
A plurality of heat exchange tubes (1) are manufactured by molding so that the n layers (14b) and (15b) are present on the outer surface. The thickness of the Zn layers (14b) and (15b) is preferably set in the range of 5 to 10 μm in order to form a reliable and effective anticorrosion layer. And these heat exchange tubes (1)
Are arranged in parallel with each other via aluminum fins (2), both ends of the tube (1) are inserted into the tube insertion holes of the headers (3) and (4), and the side plates (5) ( 5), the partition plate (6) and the refrigerant inlet / outlet pipes (7) and (8) are assembled in a predetermined arrangement to form a heat exchanger assembly.

Next, flux is applied to the heat exchanger assembly. The type of flux is not particularly limited, but it is preferable to use a non-corrosive fluoride flux. An example of the fluoride-based flux is aluminum fluoride (AlF ₃ ) component and potassium fluoride (KF).
A complex mixture containing a component in a composition range of eutectic composition or a composition close to the eutectic composition, KAlF ₄ , K ₂ Al
F ₅ , K ₃ AlF _{6 and the} like can be listed as preferable ones.
The method of applying the flux may be an electrostatic powder coating method or a suspension application.

The heat exchanger assembly coated with the flux is
Next, this is heated in an inert gas atmosphere such as N ₂ gas,
Zn layers (14b) (15) on the outer surface of the heat exchange tube (1)
b) is melted and the heat exchange tube (1) and the fin (2) are joined. By this heating, the Zn layers (14b) (15
Part of b) diffuses inside the tube (1) in the thickness direction,
A heat exchanger is manufactured in which an anticorrosion layer including a Zn layer including a diffusion layer is formed on the outer surface of the tube. The Zn layers (14b) and (15b) pre-clad on the outer surface of the tube (1) are used not only as an anticorrosion layer but also as a brazing material or a solder material for joining the tube (1) and the fin (2).

The body (14) and the lid (15) in the heat exchange tube (1) are joined to each other as shown in FIGS. 2 and 3, for example, as shown in FIGS. The Zn layer or the Al—Si brazing material (15c) is clad on the inner surface, and the Zn layer or the Al—Si brazing material (1) is
It is sufficient to melt 5c). In addition, flux may be applied to the inner surface of the tube (1) in advance. Since the inner hollow part of the tube (1) is extremely narrow,
When the flux is applied, the hollow portion may be blocked by the residue. Therefore, a coating layer containing at least one of Ni and Co is formed on the inner surface of the tube (1) in order to join the main body (14) and the lid body (15) without applying the flux inside the tube. That is also recommended. In this case, the flux applied to the heat exchanger assembly evaporates and the vapor enters the tube (1), and Ni or Co in the coating layer causes the growth of the oxide film on the aluminum surface during the temperature rising process. Blocks Zn on the inner surface of the lid (15) or the inner surface of the main body (14).
Flux-free bonding is achieved by melting the layers or brazing material (15c).

In the above description, the heat exchange tube (1) is composed of two members, that is, the main body (14) having a comb-shaped cross section and the lid (15) covering the main body (14). The exchange tube (1) is not limited to this as long as it is formed from an aluminum plate material.
It may be composed of one member as shown in FIG. The tube (101) shown in FIG. 4 has upper and lower flat wall portions (102) (1) facing each other with a space of, for example, 1 mm or less.
03) has a U-shaped bent portion (104) at one end thereof
And is brazed in a butt shape at the other end (105) to form a flat shape having an oval cross section. Then, the upper and lower plane wall portions (102) (1
03), two bent protrusions (106) (106) protruding inward are formed in the tube (101) in an alternating arrangement in the width direction of the tube (101). The bent protrusion (106) is formed by the flat wall (10).
2) (103) is bent inward in a V-shape and is formed as a bent double wall in which both side walls are in close contact with each other, and is continuous in the length direction of the tube (101).
The top ends of the bent protrusions (106) are brought into contact with the inner surfaces of the opposing flat wall portions (102) (103), respectively, and are joined and integrated with the inner surfaces by brazing. These joints are made by using the brazing filler metal by using a single-sided aluminum brazing sheet having a Zn layer or a soldering material such as A4343 or an aluminum brazing filler metal on the inner surface of an aluminum core material such as A3003 as the tube material (101). It is done by. Therefore, the joining operation is performed at the same time as the joining operation of the respective components such as the tube (101) and the fins (2) at the time of manufacturing the heat exchanger.

The heat exchange tube (101) shown in FIG.
As shown in FIG. 5, after forming a bent portion (106) at a predetermined position of a flat plate-shaped aluminum sheet, the sheet is bent in the folding direction in the widthwise central portion (104) to make a widthwise direction. It is manufactured by forming both side edges (107) (107) in a butt shape.

As shown in FIG. 4, the heat exchange tube (10
1) also enables a thin wall thickness comparable to that of the tube (1) shown in FIGS. 2 and 3, but by forming an anticorrosion layer containing Zn on the outer surface thereof, excellent corrosion resistance can be obtained. Will be owned. The anticorrosion layer may be formed by clad a Zn layer on the outer surface of the tube (101) in advance and brazing it with heat, as in the tube (1).

[0022]

EXAMPLE In manufacturing the same aluminum condenser for an air conditioner as shown in FIG. 1, first, each constituent member was temporarily assembled to manufacture a plurality of heat exchanger assemblies.

Here, the heat exchange tube is provided with a main body (14) having a comb-shaped cross section as shown in FIGS.
5) is used, the height (tube thickness) H of the outer wall (12) of the main body (14) is 1.05 mm,
The width W is 18 mm, the height (refrigerant passage height) h of the reinforcing wall (13) is 0.35 mm, and the width w of the reinforcing wall (13) is 0.4.
mm, the distance L between the reinforcing walls (13) is 2 mm, and the wall thickness t of the lid (15) is 0.35 mm. Further, the main body (14) has a Zn or A4343 aluminum brazing filler metal (14) on one side of the A3003 aluminum core material (14a).
An aluminum sheet clad with b) was formed and processed so that the Zn or A4343 aluminum brazing material (14b) was present on the outer surface. On the other hand, the lid (1
5) is Zn or A4343 aluminum brazing filler metal (15b) (15c) on both sides of the aluminum core material (15a).
The aluminum sheet clad with was molded and used. The body (14) and the lid (1
The configuration of 5) is shown in Table 1. The composition of the fin (2) is also shown in Table 1.

Next, a suspension in which flux was suspended in water was applied to each of the above heat exchanger assemblies. As the flux, KAlF ₄ , K ₂ AlF ₅ · H ₂ O, K ₃ Al
A fluoride-based flux made of a mixture of F ₆ was used.
The flux was also applied to the inner surface of the tube (1). Flux application on the inner surface of the tube was performed in advance at the stage of the tube alone before assembly.

Next, each heat exchanger assembly was used in a continuous furnace in an N ₂ gas atmosphere, O ₂ concentration: 40 ppm, dew point: −5.
0 ℃, real temperature of assembly (maximum): 590-605 ℃,
Brazing was performed under the conditions of a holding time of 577 ° C. or higher: 3 to 6 minutes.

Then, a corrosion test was conducted on each of the obtained heat exchangers. The test is based on ASTM artificial seawater and 10 ml of acetic acid.
After spraying a mixed solution of 1 liter of seawater (pH 2.8 to 3.0) for 30 minutes, leave it in a wet state for 90 minutes, repeat this cycle for 120 minutes, and measure the time until the tube leaks. did. Table 1 shows the results.

[0027]

[Table 1] From the results shown in Table 1 above, it was confirmed that the product of the present invention was superior in corrosion resistance to the conventional product.

[0028]

As described above, according to the present invention, the Zn anticorrosion layer can be formed on the entire surface of the tube, and the corrosion resistance of the entire tube can be improved regardless of the contact portion with the fin and the non-contact portion. Therefore, for example, a heat exchange tube composed of a main body having a comb-shaped cross section having outer walls in the middle in the width direction at both ends in the width direction, and a lid body covering the front end side of the reinforcing wall of the main body and joined to the main body. As described above, even if the tube is a thin-walled product made of a molded aluminum plate material, its corrosion resistance can be improved to each stage, and thus the corrosion resistance of the entire heat exchanger can be improved. Moreover, the anticorrosion layer can be formed at the same time when the tubes and the fins are joined, which has the effect of simplifying the process.

[Brief description of drawings]

FIG. 1 (a) is a front view of an aluminum condenser for air conditioning according to an embodiment of the present invention, and FIG. 1 (b) is a side view of the same.

2 is a sectional perspective view showing a main body and a lid of the heat exchange tube of the condenser of FIG. 1 separately.

3 is a cross-sectional view of the heat exchange tube of FIG.

FIG. 4 is a perspective view showing still another configuration example of the heat exchange tube.

5 is a transverse cross-sectional view showing a state in which the heat exchange tube of FIG. 4 is being formed.

[Explanation of symbols]

 1, 101 ... Tube 2 ... Lid body 12 ... Outer side wall 13 ... Reinforcing wall 14 ... Main body 15 ... Lid body 15b ... Zn layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuyuki Takahashi 6-224, Kaiyamacho, Sakai City Showa Aluminum Co., Ltd.

Claims (4)

[Claims] 1. A heat exchange tube is made of a molded aluminum plate material, and a plurality of the heat exchange tubes are arranged in parallel with each other via aluminum fins, and the tubes and the fins are joined together. In the heat exchanger, the heat exchange tube is formed by an aluminum plate material having a Zn layer on at least one surface so that the Zn layer is present on the outer surface, and the tube and the fin are joined via the Zn layer. At the same time, an aluminum heat exchanger having excellent corrosion resistance, characterized in that the Zn layer forms an anticorrosion layer on the surface of the tube. 2. A heat exchange tube having a comb-shaped main body having a reinforcing wall with an outer wall in the middle at both ends in the width direction, and a lid body covering the main body of the reinforcing wall and joined to the main body. The heat exchanger made of aluminum having excellent corrosion resistance according to claim 1. 3. A plurality of heat exchange tubes formed by an aluminum plate having a Zn layer on at least one surface and having the Zn layer on the outer surface are arranged in parallel with each other through aluminum fins. After being assembled into a core, a flux is applied to the core and then heated, and the Zn layer on the outer surface of the heat exchange tube is melted to bond the heat exchange tube and the fin, which is excellent in corrosion resistance. Method for manufacturing heat exchanger. 4. A main body having a comb-shaped cross section, wherein a heat exchange tube has reinforcing walls with outer walls in the middle at both ends in the width direction, and a lid body which is covered with the main body of the reinforcing wall and is joined to the main body. The method for producing an aluminum heat exchanger having excellent corrosion resistance according to claim 3, comprising: