JPS60187655A - Heat exchanger made of aluminum alloy - Google Patents

Abstract

PURPOSE:To develop a heat exchanger having excellent heat conductivity and heat exchangeability by joining a fin of a brazing sheet consisting of a specifically composed Al alloy core material and an Al-Si alloy facing material to an Al metal tube having the potential nobler than said fin. CONSTITUTION:A brazing sheet 5 havig 0.13-0.2mm. thickness is formed by cladding an Al-Si alloy or Al-Si-Mg alloy facing material 4 onto a core material 3 of an Al alloy consisting of <0.2% Fe, <0.1% Si, 0.01-0.3% Zr, 0.05-1.0% Zn and the balance Al as a fin for a heat exchanger. Such sheet is formed to a corrugated shape and is then brazed to a pure Al tube 1 which has a hole 2 for passage of a refrigerant and is nobler in potential than the fin material 5 to manufacture a heat exchanger. The heat exchanger which obviates buckling of the fins during brazing, and has a sacrificial anode effect and excellent heat conductivity is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides heat exchange characteristics, which are assembled by brazing and joining.
That is, the present invention relates to an aluminum alloy heat exchanger having an excellent heat exchange efficiency, and particularly to a heat exchanger having improved heat exchange performance by increasing the thermal conductivity of the fins.

Aluminum heat exchangers employing solder joints consist of passages through which a refrigerant such as Freon passes and fins that dissipate heat, and are widely used in automobiles, aircraft, etc.

Conventionally, the fins of such brazed aluminum heat exchangers are made of AIL-M n-based alloy, such as 300
3 alloy (/l-0, 15wt%Cu-1, 1wt%Mn
(Hereinafter, wt% is simply abbreviated as %]) or 3203 alloy (A
i-1,1%M n ) as the core material, and An on both sides thereof.
-Si alloy brazing filler metal, e.g. 4343 alloy (A-7,5
%St) or 4045 alloy (A-10%Si), or humanities-3j-Mg alloy brazing filler metal, such as 4004 alloy (
Au-10%5i-1,5%Mg), etc., on both sides.
A thin plate with a thickness of 0.1 to 0.2 mm, a so-called plating sheet, is used.

However, the /lj-Mn alloy used as the core material in the fin does not necessarily have the best thermal conductivity, and it is required to improve the thermal conductivity of the fin in order to improve the performance of the heat exchanger. Particularly in recent years, automotive heat exchangers have been moving towards weight reduction and downsizing in order to conserve resources and energy. ing.

The quality characteristics required for the fins of such heat exchangers are: firstly, brazing ensures that the fins do not buckle during joining, and secondly, to protect the tubes as necessary, the sacrificial anode effect Thirdly, the fins have good thermal conductivity.

The present invention was developed as a result of various studies in view of the above circumstances.
Below, ZrO, 01~0.3 wt%, ZnO
The fin of the plating sheet has a core material of an A-3i alloy containing 305 to 1.0 wt%, the balance being A-3i alloy and unavoidable impurities, and a skin material of a Hebumi-3i alloy. A9. The present invention provides an aluminum alloy heat exchanger characterized by being formed by joining a tube made of an alloy.

The heat exchanger of the present invention uses fins with significantly improved thermal conductivity without sacrificing buckling resistance, instead of the conventional fins made of A-Mn alloy as a core material. It has significantly improved heat exchange characteristics.

The action and significance of each component of the core material A1 alloy in the fins of the plating sheet used in the heat exchanger of the present invention will be explained below.

Fe and Si affect thermal conductivity and grain size. FeO
, 2% or less and SiO, 1% or less.
, Si exceeding the above range not only lowers the thermal conductivity but also reduces the recrystallized grains of direct nf1 during brazing, making it easier for the solder to diffuse, resulting in buckling of the fins.

The addition of Zr has the effect of increasing the recrystallization temperature and enlarging the crystal grains immediately before the solder to minimize the diffusion of the solder, thereby preventing buckling of the fin. The amount added is 0.
01 to 0.3% is because if it is less than 0.01%, the buckling resistance JZ of the fin will not be as expected, and if it exceeds 0.3%, coarse intermetallic compounds will be formed and the plastic workability will be impaired. This is because it not only lowers the thermal conductivity but also lowers the thermal conductivity.

Zn lowers the potential of the fin, serves as a sacrificial anode for the tube, and has the effect of suppressing pitting corrosion in the tube. If Zn is less than 0.05%, the desired sacrificial anode effect will not be sufficiently exhibited11, and if it is added in excess of 1.0%, the thermal conductivity of the fin will decrease.

In addition, other unavoidable impurities such as Cu, Mn, Mg, Cr, Ti, etc. should be contained to an extent that does not reduce thermal conductivity, that is, each
It is desirable that the content be 0.03% or less.

Next, as the skin material of the plating sheet, brazing is performed in a non-oxidizing atmosphere, or in the case of general brazing, A-3t alloy, such as AfL-7, is applied to both sides of the core material.
, 5%Si (BA4343) and Affi-10%St
(BA4045) and in the case of waxing in vacuum, A9. -31-Mg alloy, e.g. A-10%5i-1,5%Mg (BA40
04) and A sentence-10%S i -1,5%Mg-0,1
% Bi (AA4104).

Placing sheets usually have a thickness of 0.13 to 0.2 mm
It is used as a thin plate processed into a corrugated shape. This plating sheet can be manufactured by a conventional method.

In the present invention, the tube is made of an A type alloy which has a higher potential than the fin. Examples of such A-shaped alloys include JIS A1050 and Alt.

01A3003 is common, but in the present invention, in order to improve the heat exchange characteristics of the entire heat exchanger, it is preferable to use pure A1050 or Al100, which has excellent thermal conductivity.
n-type is effective.

Next, embodiments of the aluminum alloy heat exchanger of the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a perspective view of a tube of a heat exchanger. A flat multi-hole tube l formed by extrusion or the like has a plurality of holes 2 through which a refrigerant passes.

FIG. 2 is an enlarged vertical cross-sectional view of the fin material, and shows A! on both sides of the core material 3. Figure 3 shows an example of the aluminum alloy heat exchanger of the present invention (A) and (RO). ) indicate automotive air conditioner condensers and evaporators, respectively.

As is clear from the same figure, the fins 5 of the brazing seam 1 of Fig. 2, which is processed into a corrugated shape, are inserted between the bent parts of the flat multi-hole tube l of Fig. 1, which is bent in a serpentine shape. . This brazing is performed using the skin material 4 that is coated on the surface of the corrugated fin 5 in advance. In the figure, 6.7
are the inlet and outlet pipes provided at both ends of the tube.

The arrow indicates the flow direction of the cold tofu.

Note that the fin width varies depending on the specific type of heat exchanger, and there is of course no particular limit to it, but normally the fin width is about 100 m+o for an evaporator and about 18 m+o for a condenser.
It is about ~50m5.

The core consisting of the tube and corrugated I/fin can be assembled using vacuum brazing, flux brazing, or other general brazing methods, but it is not practical to do so in a non-oxidizing atmosphere. is about 600 to 60% in an N2 gas atmosphere using a small amount of fluoroalumine potassium complex salt as a medium.
Brazing at 10°C is most preferable in terms of performance and cost.

In the heat exchanger assembled in this way, the heat exchange characteristics can be evaluated by estimating the heat transfer characteristics, for example, by measuring the electrical conductivity of the fins. Alternatively, this can be done by lowering the fins in a corrugated manner, assembling them into a core as shown in FIG. 3, and actually measuring the heat exchange coefficient (cooling capacity).

EXAMPLES An A9° alloy having the composition shown in Table 1 was melted and cast using the same melting method as in the example. Next, a core material for rolling was created from this ingot by a conventional method. Although not shown in the same table, these A
All 1 alloys contain 0.02% Cu as an unavoidable impurity.
Below (0.15% for conventional example 22 only), Ti 0.0
3% or less, Mn 0.03% or less (1.1% only in Conventional Example 21.22).

Next, JIS BA4045 alloy plates (A
10% Si) is clad at a ratio of about 10% per side, and is hot rolled, followed by cold rolling, intermediate annealing, and cold rolling to a plating thickness of 0.1 ft am by a conventional method. A prototype sheet (semi-rigid) was produced. For these fin brazing seams 1- (Q, 113 am thick, width 100 m+*), the brazing seams are heated to a temperature (600 m+).
The conductivity (IAC 3%) after 13 minutes at °C was measured. The results were also listed in the same table to evaluate thermal conductivity.

In addition, these fin materials (Q, 1 fl am thickness, width 100
ffi11) is corrugated and then hot extruded into a JIS A1050 multi-hole flat tube (wall thickness 0.
8mm, width 100mm) bent into a serpentine shape and fixed with a jig as shown in Figure 3 (b).
In a gas atmosphere at 810°C, potassium fluoroaluminate complex salt (KA-F4-K AlF2) was used as a flux.
) was used for brazing. In this way, we created a prototype evaporator.

Buckling resistance test t±・Setting resistance J of fi' during brazing 4.

The gender was investigated and the results are listed in the same table. Review, 13. Eyes,
Items that were deformed to the point that they could not be used were considered defective.

Heat exchange characteristics (cooling capacity): Air volume 350m'/Hr
The test was conducted in accordance with JIS D 1618 (Automotive air conditioner test method).

Regarding corrosion resistance, a CASS test was conducted for 720 hours, and the depth of pitting corrosion occurring in the tube was measured. The maximum pitting depth is also listed in the same table. Corrosion resistance is good when it is 0.1 am or less. Comparative examples and conventional examples outside the limited range of the heat exchanger of the present invention were also tested in the same manner, and the results are shown in the same table.

] As can be seen from the results in Table 2, the heat exchanger N according to the present invention
o, 1 to 13, the conductivity of the fin is 50% or more.
2, the conductivity is 25 compared to conventional product No. 21.22.
% or more -1-improvement. In addition, the cooling capacity of all heat exchanger cores is 3,900 Kcal/Hr or more, approximately 8% higher than conventional products. Also, there is no buckling of the fins,
Furthermore, it has a good sacrificial anode effect on the tube, has a pitting depth of 0.1 mm or less, and has several times more durability than conventional products.

In addition, among the comparative examples, No, 14 to No, l6, No,
1B.

No. 20 has fin conductivity of less than 50% and the cooling capacity is almost the same as conventional products, No. 17 has buckling of the fins, No. 19 has deep pitting corrosion on the tube, etc. One of the quality items was exactly below the target value.

As described above, the aluminum alloy heat exchanger of the present invention not only has excellent heat exchange characteristics, but also has improved pore resistance due to the buckling resistance of the fins, making it a resource-saving and energy-saving heat exchanger. Extremely excellent.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an extruded multi-hole tube, Fig. 2 is an enlarged vertical sectional view showing an example of a plating sheet for fins, and Fig. 3 (a) and (b) are a condenser as an automatic heavy-duty heat exchanger, respectively. and a perspective view showing an evaporator. l...Extruded multi-hole tube 3, metal, core material 4...skin material 5-〇 and fins

Claims (1)

[Claims] (1) Fe 0.2 wt% or less, SiO, 1 wt% or less, Z r O, 01 to 0.3 wt %, Z n O,
05-1.0wt% with the remainder being AM and unavoidable impurities as the core material of the A-pattern alloy and the skin material of the Kl-3i alloy. An aluminum alloy heat exchanger characterized by being made by joining a tube made of an alloy.