JP2710173B2 - Aluminum alloy laminated heat exchanger with excellent corrosion resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated heat exchanger made of aluminum having excellent corrosion resistance.

[0002]

2. Description of the Related Art In recent years, brazing sheets made of aluminum alloy have been widely used especially in heat exchangers for automobiles. Among these heat exchangers, aluminum alloy laminated heat exchangers are exclusively used for evaporators because of their excellent heat exchange performance.

The structure of a laminated heat exchanger made of an aluminum alloy is disclosed, for example, in Japanese Patent Application Laid-Open No. 63-99496. In this structure, as shown in FIG. 2, a pair of symmetrical core plates 8, which are formed by pressing an aluminum plate into a corrugated shape,
8 ′ are joined to each other to form a tank portion 20 and a refrigerant passage portion 22 communicating with the tank portion 20 to form a core plate joined body 30, that is, a flat tube. The fins 23 are formed by laminating a plurality of fins.

In this structure, as shown in FIG. 2, the core plates 8, 8 'are formed so that the shapes thereof are symmetrical when the core plates are laminated, and a brazing sheet clad with brazing material on both sides is used. ing. Therefore, the brazing material remaining after brazing is located at the brazing sheet joint on the outer surface of the completed heat exchanger, and eutectic Si locally present in this brazing material layer and α-Al of the matrix Therefore, the brazing material surface after brazing is essentially inferior in corrosion resistance.

[0005] Since the outside of the heat exchanger is exposed to salt and other corrosive media to prevent road icing, the required level of corrosion resistance to external corrosion is quite severe.
However, in the conventional aluminum alloy laminated heat exchanger, it is difficult to meet the requirement of the external corrosion resistance in the tank most exposed to the corrosive medium.

As a countermeasure for this, (1) a surface treatment for anticorrosion is performed after brazing. (2) The potential of the core material of the brazing sheet is made 50 to 100 mV noble with respect to the brazing material, and the brazing material acts as a sacrificial corrosion material to prevent corrosion of the core material. (3) Combination of the above (1) and (2) Have been proposed or implemented. However, in these methods, for example, the corrosion resistance is improved in (1) and (3), but the cost for the surface treatment is high. In (2) and (3), the corrosion resistance is slightly improved, but the corrosion resistance is more reliably improved. There was a problem that chipping, especially at the brazing joint, corroded preferentially.

In particular, to solve the problem that the brazed portion is preferentially corroded, (4) use of a brazing sheet of brazing material containing Cu and Mn on one or both surfaces is disclosed in Japanese Patent Application Laid-Open No. 63-281795. And Japanese Patent Application Laid-Open No. 1-148489, and (5) Japanese Patent Application Laid-Open No. 1-215945 proposes to regulate the amount of Cu in the core material.

[0008]

In the method (4), when the brazing material containing Cu is used on one side and the Cu-free brazing material is used on the other surface, as shown in FIG. Material and the outer material 11 are made of Cu-free brazing material (for example, JISA4
004), the joint 1 in which the endothelial material 12 is joined
In the case of No. 5, the problem that the brazing joint is preferentially corroded can be reduced, but in the case of the joint 14 in which the other outer cover materials 11 are joined, corrosion of the joint becomes a problem. That is, Cu
In a joint to which a conventionally known brazing filler metal (for example, JISA4004) is joined, the problem that the brazing joint corrodes preferentially cannot be solved.

When the Cu-containing brazing material is used on both surfaces in the method (4), the problem of preferential corrosion of all brazing joints can be reduced, but the bracing sheet itself has a noble potential. However, since the combination is the reverse of the above (2), the brazing sheet becomes a sacrificial anode and is easily corroded from the outside, and there is a problem in the corrosion resistance of the brazing sheet other than the brazing joint. That is, in the brazing joint of FIG. 4, the problem that the brazing joints of the Cu-containing brazing materials 11 'and 12 are preferentially corroded can be reduced, but the corrosion resistance of the brazing sheet itself other than the brazing joint is different from the above (2). It becomes the opposite combination and the brazing sheet is easily corroded from the outside.

Also, in the method (5), there is a concern that the potential of the core material becomes low and is corroded from the outside. Due to such a lack of corrosion resistance, it has been regulated to reduce the thickness of the brazing sheet for cost reduction. An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to provide a laminated heat exchanger made of aluminum which is low in cost and excellent in corrosion resistance.

[0011]

The gist of the present invention is to use a brazing sheet having a sacrificial anode layer instead of a brazing material on the outer surface of the heat exchanger, to prevent corrosion pits penetrating the plate thickness, and to form a brazing material on the outer surface. The joint is formed by inserting a brazing sheet between the core plates. As a result, corrosion pits penetrating through the plate thickness due to corrosion of the core material of the sacrificial anode layer are prevented, and the sacrificial corrosion protection function also works in the brazing joint,
The feature of the present invention resides in that corrosion pits penetrating the brazing joint are prevented.

Accordingly, a first aspect of the present invention is a two-piece brazing sheet in which a swelling portion is formed at one end to form a tank element and a tube element having a heat exchanger medium passage in the remaining flat portion. A multi-layered heat exchanger made of an aluminum alloy formed by alternately stacking a large number of brazing fins and a core plate joined body having a tank portion and a heat exchanger medium passage communicating with the tank portion by joining core plates comprising In the vessel,
A core plate is an aluminum alloy laminated plate, and a first aluminum alloy is used as a core material of the core plate, and a second skin, which is more potential than the first aluminum alloy, is used as a first skin material facing the outside of the heat exchanger medium passage. An aluminum alloy is used, and an aluminum alloy brazing material is used as a second cladding material facing the inside of the heat exchanger medium passage, and the core plate assembly is attached to the mating surface facing the first cladding materials in the tank portion. A laminated heat exchanger made of aluminum alloy having excellent corrosion resistance, characterized in that a brazing sheet is inserted to form a brazed joint.

Accordingly, a second aspect of the present invention is a two-piece brazing sheet in which a tank element is formed by forming a bulging portion at one end and a tube element having a heat exchanger medium passage is formed in the remaining flat portion. Aluminum alloy laminated heat exchanger obtained by laminating a large number of brazing fins alternately with a core plate joined body comprising a tank portion and a heat exchanger medium communicating therewith by joining core plates comprising In the above, the first aluminum alloy is applied to the core material of one of the aluminum alloy laminated plates of the core plate joined body, and the first skin material facing the outside of the heat exchanger medium passage is electrically lower than the first aluminum alloy. Using a second aluminum alloy and a second brazing material facing the inside of the heat exchanger medium passage using an aluminum alloy brazing material A third aluminum alloy is used as a core material of the other aluminum alloy composite plate, and a fourth skin, which is more electrically potential than the third aluminum alloy, is used as a third skin material facing the outside of the heat exchanger medium passage. The aluminum alloy is exposed to the core material inside the heat exchanger medium passage, or a fourth skin material made of an aluminum alloy other than the brazing material is applied, and the brazing joints of the two aluminum alloy ply plates are joined together. Only one of the mating surfaces is such that the second cladding material faces the other aluminum alloy plywood or the fourth cladding material as a brazing material surface, and the core plate joined body is the first skin in the tank portion. A laminated heat exchanger made of an aluminum alloy having excellent corrosion resistance, characterized in that a brazing sheet is formed by inserting a brazing sheet into a mating surface where the material and the third skin material face each other.

[0014]

In the present invention, since the sacrificial corrosive material is provided on the outer surface of the core plate constituting the heat exchanger tank portion and the heat exchanger medium passage tube communicating therewith, corrosion penetrating the tank portion is prevented. It is completely corroded until the sacrificial corrosive material on the outer surface disappears. In the first embodiment of the present invention, a countermeasure against corrosion penetrating the brazing joint will be described with reference to FIG.

FIG. 1 shows an enlarged cross section of the brazing joint between the core plates 8, 8 '. The brazing metal 31a formed by the brazing and the reaction of the skin material with the endothelial material brazing portion 31 to which the endothelial material (that is, the second skin material) 12 of the core plates 8, 8 'is joined is mainly composed of Brazing material is accumulated. The potential is usually equal to or more noble than that of the core material 10 and the sacrificial anticorrosive effect of the outer skin material (that is, the first skin material) 11 serving as a sacrificial anode on the outer surface. The attachment portion 31 is protected in a sacrificial manner, so that no corrosion leading to penetration occurs.

The outer material brazing portion 35 of the core plates 8, 8 'to which the outer materials 11 are joined is brazed using a brazing sheet. This sheet may be a brazing sheet 32 as shown in the drawing, or
A fin brazing sheet may be used. When the fin brazing sheet is used, the tip of the fin may be used for brazing inside the tank portion. The joining metal 35a in the brazing portion of the outer shell material is mainly formed by accumulating the brazing material 34 of the brazing sheet 32, and as a result of the erosion of the outer shell material 11 having a sacrificial anticorrosion effect, the joining metal 35a is formed.
35a is protected against corrosion. Since the brazing material 34 erodes and melts the outer cladding material 11 when a brazing joint is made, the potential of the brazing material is equal to the potential of the brazing material 34 of the brazing sheet 32 and the potential of the outer cladding material 11. Brazing the endothelial material
Fall short of parts 31 in sacrificial protection to effect, junction metal 3
5a is also sacrificed.

Further, when Cu is added to the brazing material (endothelium 12) of the core plates 8, 8 ′ to increase the potential of the brazing material by adding 0.1 to 1.0%, particularly at the brazing portion 31 of the endothelial material. Anticorrosion effect can be expected.

In the second embodiment of the present invention, as shown in FIG. 5, the core material (10a) of one aluminum alloy laminated plate (8) -the first aluminum alloy; faces the outside of the heat exchanger medium passage. A first skin material (11a)-a second aluminum alloy which is more potential than the first aluminum alloy;
Second skin facing the inside of the heat exchanger media passage (12a)
A core material (10b) of the other aluminum alloy laminated plate (8 '), which is an aluminum alloy brazing material; a third aluminum alloy; a third skin material (11b) facing the outside of the heat exchanger medium passage; A fourth aluminum alloy which is lower in potential than the third aluminum alloy; a core material (10b) is exposed inside the heat exchanger medium passage or a fourth skin material (12b) made of an aluminum alloy other than brazing material ).
The core material (10a, 10b) and the outer material (11
a, 11b) Comrades usually consist of the same type of aluminum alloy. The first skin material (11a) and the third skin material (12b)
Insert the brazing sheet (32) into the mating surface facing
Brazing is performed as in the case of FIG .

The brazing material on the inner surface thus (inner covering 12
a core plate 8 which arranged b), the core plate 8 without distributing the brazing material on the inner surface '(and if not the inner covering 12 b gallery material, there are two aspects in the case where the inner covering 12 b are omitted) Were alternately laminated to form a core plate assembly such that the brazing material surface 12b was located only on one surface of the endothelial material brazing portion 31. With this configuration, a better brazed joint is formed than when the inner brazing material is present on both core plates. The reason is considered as follows. That is, as shown in FIG. 6, the size of the fillet (fillet) formed by the brazing joint is the second for the combination joint of the brazing sheet 41 and the non-brazing sheet 40 (when the brazing material 43 is present on only one surface). It corresponds to the brazed joint of the invention.
The combination of the brazing sheets 41a and 41b shown in FIG. 7 corresponds to the brazing joint of the first invention. The size of the fillet 44 is not clear at this time, but the combination of the brazing sheet 41 and the non-brazing sheet 40 (FIG. 6) is brazing due to the difference in the presence or absence of the solid surface tension at the wetting tip of the wax. Sheets 41a, 41b
It is larger than the combination of comrades (FIG. 7). That is, in the fillet portion, the surface tension of the solid, the tension at the solid-liquid interface, and the surface tension of the liquid act to determine the size of the fillet 44 by the balance of these forces. In the combination of FIG. 6, the fillet is increased due to the large surface tension of the solid, whereas in the combination of FIG. 7, the fillet 44 is considered to be smaller than in the combination of FIG. 6 because the solid has no surface tension.

[0020]

The present invention will be described more specifically below. The aluminum alloy for the core material of the laminated plate (first and third aluminum alloys) is not particularly limited as long as it has excellent strength, formability, brazing properties, etc.
951, Al-Mn system, Al-Mn-Cu system, Al-M
g-Si system, Al-Mg-Si-Cu system, Al-Mg-
Si-Cu-Mn type is a preferable application example.

The aluminum alloy for the skin material (second and fourth aluminum alloys) that comes into contact with the outside air outside the heat exchanger medium passage tube is not particularly limited as long as it is an aluminum alloy that is more potential than the core material. , Pure Al system, Al-
Zn-based, Al-Sn-based, Al-In-based and combination alloys of these component systems are preferred examples of this application.

The aluminum alloy brazing material (third aluminum alloy) for the cladding material that contacts the cooling medium inside the heat exchanger medium passage tube is not particularly limited, but is JIS A400.
3,4004,4005,4N04,4104,434
3, 4045, etc., or those in which the Mg content of these alloys is 0.1 to 1.0%, and furthermore, alloys in which 0.05 to 1.0% of Cu is added to these alloys are preferable application examples. . Although the brazing sheet fin material is not particularly limited, JISBA4PC, BA8PC, BA10P
C, BA12PC, BA18PC, etc. are preferred application examples.

The brazing sheet may be a brazing sheet alone or a brazing sheet. When the brazing sheet is a brazing sheet, the brazing sheet fin 2 is corrugated as shown in FIG.
The third end 23a may be extended and inserted between the core plates 8, 8 '. When the brazing sheet is a sheet containing only brazing material, the brazing material alloy is not particularly limited, but may be JIS A4.
003,4004,4005,4N04,4104,4
343, 4045 and the like, and further, Cu is added to these alloys in an amount of 0.1%.
An alloy to which 0.05 to 1.0% is added is a preferable application example.
When the brazing sheet is a brazing sheet, there is no particular limitation, but JISBA4PC, BA8PC, B
A10PC, BA12PC, BA18PC and the like, and further, at least one of the brazing material and the core material of these alloys is made of Cu.
Is a preferable application example.

[0024] The plywood which does not use the aluminum alloy brazing material for the endothelial material may omit the endothelial material. However, when the endothelial material is used, the alloy of the endothelial material may be the same as that of the aluminum alloy for the outer material, or this An alloy containing 2% or less of Mg, Bi, Be, or the like in a skin material alloy may be used. Although the cladding ratio is not particularly limited, a preferable range is 3 to 20%.

As the brazing method, vacuum brazing, flux brazing, non-corrosive flux brazing, and the like are preferably applicable, but are not particularly limited. Further, when a plurality of bonded core plate assemblies are stacked and temporarily assembled and held on a jig, as shown in FIG.
A burring portion 8a is provided at the end of the core plate to prevent displacement between the 8 'and the caulking joint with the fitting hole, or a tongue piece for caulking is formed instead of the burring. Using the tongue piece 48, the mating member 8, 8 '
It may be crimped and joined. 9 and FIG.
Description will be made based on 0. FIG. 7 is a perspective view showing the entire stack type heat exchanger. In FIG. 9, 8, 8 'are core plates,
20 is a tank part, 21 is a passage pipe penetrating the tank part 20, 22 is a heat exchange medium passage, and 23 is a fin.

FIG. 10 is a sectional view in which the core plates 8, 8 'and the corrugated fins 23 are laminated. The core plates 8 and 8 'are made of pure aluminum 1070 as a skin material, a 3003 (Al-1Mn-0.15Cu) alloy as a core material, and a brazing alloy (Al-10Si-1.5M) as an endothelial material.
g-0.3Cu) (0.4 m thick)
m, cladding rate 10%). In addition, the corrugated fins 23 are made of a brazing alloy (Al-10Si) as a cladding material on both surfaces.
A brazing sheet (plate thickness: 0.16 mm, cladding ratio: 15%) using 3003 alloy as a core material of -1.5Mg-0.15Cu) was used.

This core plate was pressed so as to be symmetrical with the core plate 8 and the core plate 8 'for forming the tank portion 20, the passage tube 21 passing through the tank portion, and the medium passage tube for passing the refrigerant. In the stacked heat exchanger, a set in which a core plate 8 and a core plate 8 'were combined was alternately stacked with corrugated fins. Corrugated fins 23 were inserted into the inner surface of the tank portion 20 where the outer skin materials came into contact with each other with an extension 23a. Further, the inner wall material was brought into contact with each other at 24 in order to define the cooling medium passage 22 in a tubular shape. In this way, the brazing joint into which the 23 is inserted (that is, the brazing material brazing portion 35) and the brazing joint in which the surfaces of the brazing material 12 are positioned on both surfaces of the mating surface (that is, the brazing material 31) are alternately arranged. Arranged to form tanks and heat exchanger media passage tubes. These core plates 8 and core plates 8 'are alternately stacked as shown in FIG. 10 and vacuum brazing is performed with the corrugated fins 32 incorporated between the core plates (vacuum degree 5 × 10 ^-5 torr, 600
(° C. × 5 minutes) to prepare a heat exchanger.

Thereafter, the brazing parts 24, 3 of this heat exchanger
Examination of the cross sections of Nos. 1 and 35 revealed that the joints were formed well in all cases. Further, the heat exchanger thus obtained was examined by a corrosion resistance test (salt spray 35 ° C., 4000 hours).
Table 1 shows the results. For comparison, as shown in FIG. 11, the material of the core plates 8, 8 'was a leather material 1 on both the inner and outer surfaces.
1a and 12 are brazing sheets of brazing material (thickness 0.6
mm, 4004/3003/4004). The thickness of this brazing sheet was 0.2 mm thicker than that of the example. The brazing material surfaces are positioned on both sides of the mating surfaces of the brazing joints 24, 31, and 35, and the non-matching plate 3003 (sheet thickness 0.13
mm) material and the heat exchanger was manufactured in the same manner as in the above embodiment except that the end of the corrugated fin was separated from the mating surface of the core plates 8, 8 '. Thereafter, the heat exchanger was subjected to a chromate treatment for corrosion prevention, and corrosion resistance was examined by the salt spray test. Table 1 shows the results.

[0029]

[Table 1] From Table 1, it can be seen that the heat exchanger of the present invention has a small thickness and does not cause penetration corrosion even though the surface treatment after brazing is omitted.

Embodiment 2 A core plate and corrugated fins are laminated in the same manner as in Embodiment 1. However, as shown in FIG. 12, pure aluminum 1070 is used for the outer material 11 of the core plate 8 and Al is used for the core material 10 as shown in FIG. -1Mn-0.15Cu alloys, each without an endothelial material (plate thickness 0.4 mm, clad ratio 10
%), A heat exchanger was prepared in the same manner as in Example 1 except that the brazing material surface was located only on one surface of the brazing joint 31 (the brazing portion of the endothelial material). Thereafter, the results of a wetting test in which water at 10 atm was passed through the tank unit 20 and the refrigerant passage 22 to 100 heat exchangers are shown in Table 2 in terms of the number of wet locations. In addition, the comparative example was described in Example 1.
Same as the ones .

[0031]

[Table 2] Table 2 shows that the heat exchanger of the present invention has high reliability of the brazing joint.

[0032]

As apparent from the above description, particularly from the embodiments, the present invention has the following advantages as a result of improving the corrosion resistance of the heat exchanger. Since the thickness of the brazing sheet can be significantly reduced, not only the cost can be reduced but also the weight of the entire heat exchanger can be reduced. Since the surface treatment after brazing can be omitted, the cost for the surface treatment itself and the cost for the post-treatment can be reduced. Further, it is possible to provide an aluminum laminated heat exchanger having no leakage failure at the brazing portion.

[Brief description of the drawings]

FIG. 1 is a view showing a brazing joint according to the first embodiment of the present invention.

FIG. 2 is a diagram showing a main part of the stacked heat exchanger.

FIG. 3 is a diagram showing how to use a brazing sheet in a conventional example.

FIG. 4 is a diagram showing how to use a brazing sheet in a conventional example.

FIG. 5 is a view showing a brazing joint according to a second embodiment of the present invention.

FIG. 6 is a diagram of a joint between a brazing sheet and a non-brazing sheet.

FIG. 7 is a view of a joint between brazing sheets.

FIG. 8 is an explanatory view of a method of reinforcing a brazing joint.

FIG. 9 is a perspective view of a stacked heat exchanger.

FIG. 10 is a cross-sectional view illustrating a main part of the heat exchanger according to the first embodiment.

FIG. 11 is a cross-sectional view illustrating a main part of a heat exchanger of a comparative example.

FIG. 12 is a cross-sectional view illustrating a main part of a heat exchanger according to a second embodiment.

[Explanation of symbols]

 Reference Signs List 8 core plate 10 core material 11 skin material 12 endothelial material 20 tank 21 passage pipe 23 fin 30 core plate joined body 32 brazing sheet

Claims (6)

(57) [Claims] 1. A core plate consisting of two brazing sheets forming a tank element by forming a bulge at one end and forming a tube element having a heat exchanger medium passage in the remaining flat part. (8,
8 ′), the core plate assembly (30) having the tank portion (20) and the heat exchanger medium passage (22) communicating therewith, and the brazing fin (2).
3) in a laminated heat exchanger made of aluminum alloy, in which a large number of layers are alternately laminated, an aluminum alloy laminated plate is used as the core plate (8, 8 ′), and the first aluminum alloy is coated on the core material (10). A second aluminum alloy, which is lower in potential than the first aluminum alloy, on the first skin (11) facing the outside of the heat exchanger medium passage (22), and the heat exchanger medium passage (22). An aluminum alloy brazing material is used for each of the second skins (12) facing the inside of the tank, and the core plate assembly (30) is aligned with the first skins (11) facing each other in the tank part (20). A laminated heat exchanger made of aluminum alloy having excellent corrosion resistance, wherein a brazing joint is formed by inserting a brazing sheet (32) into the surface. 2. The aluminum alloy laminated heat exchanger according to claim 1, wherein the aluminum alloy brazing material of the second skin material (12) contains 0.1 to 1.0% of Cu. . 3. The laminated heat of aluminum alloy according to claim 1, wherein the brazing aluminum alloy of the brazing sheet contains 0.1 to 1.0% of Cu. Exchanger. 4. A core plate consisting of two brazing sheets forming a tank element by forming a bulge at one end and forming a tube element having a heat exchanger medium passage (22) in the remaining flat part. (8,
8 ′), the core plate assembly (30) constituting the tank portion (20) and the heat exchanger medium (22) communicating therewith, and the brazing fin (23).
And a core material (10a) of one of the aluminum alloy laminated plates (8) of the core plate joined body (30) in the aluminum alloy laminated heat exchanger in which a large number of
The first aluminum alloy to the heat exchanger medium passage (2
A second aluminum alloy, which is lower in potential than the first aluminum alloy, is applied to the first skin material (11a) facing the outside of 2), and a second aluminum alloy facing the inside of the heat exchanger medium passage (22). A laminated plate using an aluminum alloy brazing material for the cladding material (12a), a third aluminum alloy for the core material (10b) of the other aluminum alloy laminated plate (8 '), and a heat exchanger medium passage (22) ) Is filled with a fourth aluminum alloy, which is lower in potential than the third aluminum alloy, in the third skin material (11b) facing the outside of the heat exchanger medium passage (2).
The core material (10b) is exposed on the inside of 2) or a fourth skin material (1) made of an aluminum alloy other than the brazing material is used.
2b), and the second cladding material (12a) is used as a brazing material surface only on one of the surfaces of the brazing joints of the two aluminum alloy laminated plates (8, 8 '). 8, 8 ') or the fourth skin material (1
2b) and the core plate assembly (30) is connected to the tank portion (20) by the first skin material (11a).
And a third skin material (12b), wherein a brazing sheet (32) is inserted into a mating surface facing each other to form a brazed joint, and a laminated heat of aluminum alloy having excellent corrosion resistance is formed. Exchanger. 5. The heat exchanger according to claim 4, wherein the aluminum alloy brazing material of the second cladding material contains 0.1 to 1.0% of Cu. . 6. The aluminum alloy laminated heat according to claim 4, wherein the aluminum alloy brazing material of the brazing sheet (32) contains 0.1 to 1.0% of Cu. Exchanger.