JPH04131698A - Lamination type heat exchanger made of aluminum alloy excellent in resistance to corrosion - Google Patents

Abstract

PURPOSE:To obtain a heat exchanger, excellent in corrosion resistance, at a low cost by a method wherein a pair of core plates are constituted of a clad material, in which a core material consisting of an aluminum alloy, an outer skin member consisting of another aluminum alloy inferior to the core material in electric potential and an inner side skin material consisting of aluminum brazing material positioned at the inside of a heat exchanger medium passage tube and a tank are cladded. CONSTITUTION:A pair of core plates 1, 1' are constituted of a cladded material consisting of a core material 8, consisting of an aluminum alloy, an outer skin material 7', consisting of another aluminum alloy inferior to the core material 8 in electric potential thereof, and an inner skin material, positioned at the inside of heat exchanger medium passage tube and a tank 3 and consisting of aluminum alloy brazing material 9, which are cladded. At least one of the core plate or the inner skin material is provided with a curved surface mating with an opposed surface at a part whereat the outer skin materials 7' of a pair of core plates 1, 1' are laminated, whereby the lamination type heat exchanger made of the aluminum alloy, in which both core plates 1, 1' are bonded with the curved surfaces and which is excellent in a resistance to corrosion, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to an aluminum alloy laminated heat exchanger having excellent corrosion resistance.

In recent years, aluminum alloy plating sheets have been increasingly used, especially in heat exchangers for automobiles. Among these heat exchangers, aluminum alloy laminated heat exchangers are used exclusively in evaporators called "Dron cup type" due to their excellent heat exchange performance. The overall view of such an evaporator is shown in the perspective view of FIG. 11. In FIG. 11, 1.1' is a core plate, 2 is a fin, 3 is a tank section, 5 is a passage pipe passing through the tank section 3, and 4 is a medium passage pipe through which refrigerant passes.

[Prior Art 1] The structure of an aluminum alloy laminated heat exchanger is, for example, as shown in Japanese Unexamined Patent Publication No. 63-99496, which includes a pair of symmetrical core plates formed by press-forming aluminum plates.
A core plate assembly, that is, a flat tube, is formed by joining the core plates 1 and 3 to form a refrigerant passage section 4 that communicates with the tank section 3,
It is manufactured by laminating a large number of such core plate assemblies and fins.

In this structure, as shown in Fig. 12, the core plate 1
．． 1' uses a plating sheet which is formed so that its shape becomes symmetrical when the core plates are laminated, and in which both sides of a core material 8 are clad with a brazing material 9. The entire structure is made by stacking a set of core plates 1 and 1', that is, a core plate assembly and fins 2 alternately.

AJ2-3i alloy is used as the brazing material.
Examples include AA alloy designation 4003.4004.

The residual brazing filler metal after brazing is exposed on the outer surface of the conventional heat exchanger as described above, and since eutectic Sl is locally present in this brazing filler metal layer, it is not known as eutectic SI. A
Since galvanic corrosion with the I2 matrix is unavoidable and the brazing filler metal surface after brazing has essentially poor corrosion resistance, the outer surface of the heat exchanger is susceptible to corrosion due to corrosive media in the surrounding atmosphere, such as salt. easy to be

The level of corrosion resistance required for the corrosive media to which the external surface of the heat exchanger is exposed is quite strict, so it has been difficult for conventional aluminum alloy laminated heat exchangers to meet the external corrosion resistance requirements.

As a countermeasure, (1) perform surface treatment for anticorrosion after brazing; (2) set the potential of the core material of the plating sheet to 50 to 100 mV relative to the brazing material, and make the brazing material act as a sacrificial corrosive material to (3) Methods such as combining (1) and (2) above have been proposed or implemented.

[Problems to be solved by the invention] However, methods (1) and (3) of these methods improve corrosion resistance but increase the cost for surface treatment, while methods (2) and (3) improve corrosion resistance slightly but However, the corrosion resistance itself is not reliable, and there is a problem that not only through holes occur in the plating sheet but also the joint strength deteriorates due to preferential corrosion of the solder in the solder joints. Ta.

Furthermore, even if an attempt was made to reduce the thickness of the plating sheet in order to reduce costs, there was a problem in that the reduction in the plate thickness was restricted due to the problem of corrosion resistance as described above.

The object of the present invention is to eliminate the drawbacks of the prior art described above and to provide an aluminum laminated heat exchanger that is low in cost and has excellent corrosion resistance.

[Means to solve the problem]

The gist of the invention is that a sacrificial anode layer is placed on the outer surface instead of a brazing material, and the joint shape is devised so that the pair of plating sheets can be joined only by the brazing material on the inner surface of the heat exchanger. It is in.

That is, the first aspect of the present invention is to join two core plates in which a tank element is formed by the swollen portion at one end, and a tube element having a heat exchanger medium passage is formed by the remaining flat portion. , an aluminum alloy laminated heat exchanger formed by alternately laminating a large number of brazing sheet fins and a core plate assembly constituting a tank portion and a heat exchanger medium passage tube communicating therewith, wherein the pair of cores The plate includes a core material made of an aluminum alloy, an outer skin material made of an aluminum alloy that is more base in potential than the core material, and an inner skin material made of an aluminum alloy brazing material located inside the heat exchanger medium passage pipe and tank. At least one of the core plates has a curved surface such that the inner skin material faces the other surface in a portion where the outer skin materials of the pair of core plates are laminated together, and The present invention relates to an aluminum alloy laminated heat exchanger with excellent corrosion resistance, characterized in that both core plates are joined by a curved surface.

The second aspect of the present invention is to form a tank element by joining two core plates in which a tank element is formed by a bulging part at one end and a tube element having a heat exchanger medium passage is formed by the remaining flat part. In an aluminum alloy laminated heat exchanger formed by alternately laminating a large number of brazing sheet fins and a bonded body of core plates constituting a heat exchanger medium passage pipe communicating with the core plate, the pair of core plates One of the core plates is composed of a core material made of an aluminum alloy and a first composite material clad with a skin material made of an aluminum alloy that is more base in potential than the core material, and the other core plate is a core material made of an aluminum alloy. A second combination of cladding material, an outer skin material made of an aluminum alloy that is less electrically potential than the core material, and an inner skin material made of an aluminum alloy brazing material located inside the heat exchanger medium passage pipe and tank. In the portion where the outer skin materials of the pair of core plates are laminated together, the second core plate has a curved surface such that the inner skin material faces the mating surface, and this curved surface allows both core plates to The present invention relates to an aluminum alloy laminated heat exchanger with excellent corrosion resistance, characterized in that the aluminum alloys are bonded together.

Here, the aluminum alloy for the core material of the laminated plate may be any material as long as it has excellent strength, formability, brazing property, etc., and is preferably JISA 3003, 6951, although not particularly limited.
．． Al-Mn system, Al-Mn-Cu system, Al-Mg-
3i system, A1-Mg-5L-Cu system, AlAl-Mg
-5i-Cu- system etc. can be applied.

The aluminum alloy for the skin material on the outside of the heat exchanger medium passage tube may be an aluminum alloy that is more base in potential than the core material (although it is not particularly limited, it is preferably pure Al type, Al
-Zn series, Al-5n series, Al-In series, combination alloys of these component systems, etc. can be applied.

The aluminum alloy filler metal for the inner skin material on the inside of the heat exchanger medium passage tube is not particularly limited, but is JISA4003.
,4004,4005°4NO4,4104,4343
, 4045, etc. can be preferably applied.

The brazing sheet fin (hereinafter referred to as "fin") material is not particularly limited, but is preferably JISBA4PC.
, BAIOPC, BA12PC.

BA18PC etc. can be applied.

Examples of the joint shape in which the brazing joint in the heat exchanger according to claim 1 has few mating surfaces (the brazing metal surface is located on one surface) are shown in FIGS. There is no limitation to the joining shape shown in these figures.The core plate 1.1' shown in these figures is clad with a brazing material 9 on the inside of a core material 8 and an outer skin material 7' serving as a sacrificial anode on the outside. The brazed joint is made of a laminated plate according to claim 1.
1.12, the brazed joint 10.12 and the brazed joint 11 have different joining shapes. If the symmetrically shaped core plate has the solder metal 9 in the facing part of the core plate stack, a symmetrically shaped solder joint 10.12 is produced.

On the other hand, in the brazing joint 11, if the core plate 1' and the core plate 1 are stacked in a symmetrical shape, the sacrificial anode materials of the outer skin material 7' will face each other, making it impossible to join. The soldering material 9 is made to have an asymmetrical shape, and the tip 6 of 1' is bent by 180 degrees so that the brazing material 9 is joined to the outer skin material 7'.

Furthermore, in various core plate shapes as shown in FIGS. 2 and 3, the tip of the core plate 1' is given a curved surface shape, and the brazing material 9 is joined to the outer skin material 7' of the core plate 1. That's what I do.

Figures 4 to 6 correspond to Figures 1 to 3, respectively, and use the same reference numerals, but instead of core plate 1,
The core material 8 and the outer skin material 7' are made without using the inner skin material made of brazing material.
This shows a heat exchanger using a core plate 1'' consisting of a sacrificial anode (sacrificial anode). Examples in which laminated plates of No. 1 and 1 are alternately laminated are shown in FIGS. 4 to 6.

Also, as shown in FIG. 8, both core plates 1.1'
The tip 6 may be curved to form a braze joint for joining the brazing materials 9' together.

Furthermore, as shown in FIG. 7, in order to make the sacrificial anticorrosion effect of the outer skin material more effective in the solder joint 10, a core plate 1.1' may be brought into close contact with the solder joint 10.

Although not shown, the first laminated plate (without using an aluminum alloy brazing filler metal for the inner skin material) has the same composition as the aluminum alloy for the outer skin material, or the alloy includes Mg, Bi,
An inner skin material made of an alloy containing 2% or less of Be or the like may also be used.

Furthermore, in order to prevent misalignment between the core plates when temporarily assembling multiple core plate assemblies and holding them in a jig, a burring is provided at the end of the core plate to prevent the fitting holes from forming. A caulking member may be joined between the parts, or a caulking tongue piece may be formed in place of a burring, and the tongue piece may be used to caulk and join the mating member.

[Effect]

The reason why the heat exchanger of the present invention has excellent corrosion resistance is that a sacrificial corrosive material is placed on the outer surface of the core plate that constitutes the tank part of the heat exchanger and the heat exchanger medium passage pipes communicating with the tank part of the heat exchanger. This is because the materials and joints are completely protected from corrosion until the sacrificial corrosion material disappears.

Furthermore, even in the situation where the second core plate with the brazing metal only on the inner surface and the first core plate without the brazing metal on the inner surface are laminated alternately, the brazed joint can form a good brazed joint. The brazing material surface is positioned only on one of the mating surfaces.

In other words, the size of the fillet 22 formed in a brazed joint is as shown in FIG. 9 when the joint is a combination of a praising sheet 20 and a non-prising sheet 21 (when there is a brazing material on only one side). This is because the joint is larger than the combined joint of plating sheets 20 shown in FIG. The reason for this is not necessarily clear at present, but it is thought to be due to the difference in the presence (in the case of FIG. 9) or absence (in the case of FIG. 10) of the surface tension of the solid at the wetted tip of the wax.

That is, the surface tension of the solid, the tension of the solid-liquid interface, and the surface tension of the liquid act on the fillet portion, and the size of the fillet 22 is determined by the balance of these forces. In the combination shown in Figure 9, the fillet 22 is thicker (because the surface tension of the solid is large), whereas in the combination shown in Figure 1O, the fillet 22 is thought to be smaller than the combination shown in Figure 9 because there is no surface tension of the solid. .

The present invention will be explained below with reference to Examples.

[Example] Example 1 Hereinafter, an example of claim 1 will be described based on FIG.
An embodiment of claim 2 will be described based on the drawings.

FIG. 1 is a sectional view of the core plates of claim 1 stacked together with fins interposed therebetween. This core plate 1.1' has pure aluminum 1070 as the skin material 7 on its outer surface and A as the core material 8.
A laminated plate (plate thickness 0°4m) with l-lMn-0°3Cu alloy and brazing alloy 4004 as the inner skin material 9.
m and cladding rate of 10% each). Also fin 2
4004 for the skin material on both sides and 3003 plating sheet for the core material 8 (plate thickness 0°16mm cladding rate 10% each)
is used. This core plate 1.1' is attached to the tank part 3.
．． 3' Pressing is performed to form a passage pipe 5 penetrating the tank portion and a heat exchange medium passage pipe 4 through which the refrigerant passes.

In this case, the core plate 1 and the core plate 1' are members in which the tank portion 3 and the tank portion 3' are asymmetrical, and the medium passage pipe 4 is symmetrical.

In the tank part 3', the tip part 6 forming the passage pipe 5 penetrating the tank part is tightly targeted on the outer surface, and when the core plates 1 and 1' are stacked alternately, the brazed joint 11 A filler metal surface (
9) so that the outer skin material 7 is located on the other side. The brazed joints 10.12 forming the tank 3 and the heat exchanger medium passage pipes 4 have brazing metal surfaces (9) on both mating surfaces.
) is located.

These core plates 1 and 1'' are stacked alternately as shown in Fig. 3, and fins 2 are installed between the core plates.
0-'torr, 600°C x 5 minutes) to create a heat exchanger.

Thereafter, when the cross sections of the brazed joints 10, 11, and 12 of this heat exchanger were examined, it was found that the joints were all well formed.

Furthermore, the heat exchanger obtained in this way was examined by a corrosion resistance test (salt water spray at 35°C for 4000 hours), and the results were evaluated in the first test.
Shown in the table.

For comparison, a core plate l as shown in FIG.
The plating sheet is symmetrical in shape, and the skin material 7.9 on both the inner and outer surfaces is brazing material (thickness 0, 6 mm,
4004 / 3003 / 4004), so that the brazing metal surfaces 9 are located on both sides of the mating surfaces of the solder joint 10, 11, 12, and the fin material 2 is made of a non-matching plate 3003 (plate thickness 0° A heat exchanger was manufactured in the same manner as in the above invention example except that a 13 mm) material was used.

Thereafter, this heat exchanger was subjected to chromate treatment to prevent corrosion, and its corrosion resistance was similarly examined. The results are shown in the same Table 1.

Example 2 As shown in FIG. 4, the core plate 1'
1" and fins 2 are laminated together. In this case, the core plate 1 has pure aluminum 1070 as the skin material 7 on the outer surface of the core plate 1.
For the core material 8, an Al-lMn-0,3Cu alloy was used, and a laminated plate (thickness 0.4 mm, cladding ratio 10%) with no inner skin material was used. Example 1 except that the filler metal surface was positioned only in
A heat exchanger was created in the same manner.

After that, we conducted a leak test on this heat exchanger and reported the results in a second test.
In the leakage test shown in the table, a water pressure test (10 atm) was conducted on 100 heat exchangers and the results were judged based on the number of leakage points. Furthermore, the corrosion resistance test was omitted because the conditions were the same as in Example 1.

For comparison, a heat exchanger shown in FIG. 11 was manufactured in the same manner as in Example 1, and its leakage properties were similarly examined. The results are shown in the same Table 2.

(Left below) [Effects of the Invention] As shown in the examples above, according to the present invention, it is possible to: ■ Significantly reduce wall thickness; ■ Surface treatment of the brazed portion can be omitted; ■ Furthermore, under the conditions of ■■ However, it is possible to provide an aluminum laminated heat exchanger with excellent corrosion resistance and no leakage defects, resulting in significant performance improvements and cost reductions.

[Brief explanation of drawings]

1 to 3 are cross-sectional views showing the main parts of the heat exchanger according to the embodiment of claim 1, and FIGS. 4 to 6 are cross-sectional views showing the main parts of the heat exchanger according to the embodiment of claim 2. 7 is a sectional view showing the main parts of a heat exchanger according to another embodiment of claim 1, FIG. 8 is a sectional view showing the main parts of a heat exchanger according to another embodiment of claim 2, Fig. 9 is an explanatory diagram of brazing between a plating sheet and a non-prazing sheet, Fig. 10 is an explanatory diagram of brazing of a plating sheet and a plating sheet, Fig. 11 is a perspective view of a laminated heat exchanger, FIG. 12 is a sectional view of the main parts of a conventional laminated heat exchanger.

Claims (3)

[Claims] 1. By joining two core plates in which the bulge at one end forms a tank element and the remaining flat part forms a tube element having a heat exchanger medium passage, the tank part and the heat exchanger connected to it are joined. In an aluminum alloy laminated heat exchanger formed by alternately laminating a large number of core plate assemblies constituting exchange medium passage pipes and brazing sheet fins, the pair of core plates have a core material made of an aluminum alloy and a core plate made of an aluminum alloy. , consisting of a cladding material made of an outer skin material made of an aluminum alloy that is more base in potential than the core material, and an inner skin material made of an aluminum alloy brazing material located inside the heat exchanger medium passage pipe and tank. In a portion where the outer skin materials of the pair of core plates are laminated, at least one core plate has a curved surface such that the inner skin material faces the other surface, and both core plates are joined by this curved surface. An aluminum alloy laminated heat exchanger with excellent corrosion resistance. 2. By joining two core plates, in which the bulge at one end forms a tank element and the remaining flat part forms a tube element having a heat exchange medium passage, the tank part and the heat exchanger connected thereto are joined. In an aluminum alloy laminated heat exchanger formed by alternately laminating a large number of bonded core plates constituting medium passage pipes and brazing sheet fins, one of the pair of core plates is made of an aluminum alloy. It is composed of a core material and a first laminate material clad with an outer skin material made of an aluminum alloy that is more base in potential than the core material, and the other side of the core plate is made of a core material made of an aluminum alloy and a first cladding material made of an aluminum alloy that has a lower potential than the core material. It is composed of a second composite material clad with an outer skin material made of a politically base aluminum alloy and an inner skin material made of an aluminum alloy brazing material located inside the heat exchanger medium passage pipe and tank, and In the portion where the outer skin materials of the core plate are laminated, the second core plate has a curved surface such that the inner skin material faces the mating surface, and both core plates are joined by this curved surface. Aluminum alloy laminated heat exchanger with excellent corrosion resistance. 3. 3. The laminated aluminum alloy heat sink having excellent corrosion resistance as claimed in claim 2, characterized in that an inner skin material made of an aluminum alloy that is more base in potential than the core material of the first core plate is clad on the inside of the core material. exchanger.