JPH02127992A - Heat exchanger made of aluminum - Google Patents

Abstract

PURPOSE:To improve brazing of respective parts by specifying the compsn. of brazing filler metals clad on the surfaces of aluminum sheets which constitute liquid flow tubes and specifying the compsn. of the brazing filler metals clad on the surfaces of the aluminum sheets for constituting seat plates. CONSTITUTION:An Al alloy which consists essentially of Al and contains 6.8 to 8.2wt.% silicon is used as the brazing filler metals to be clad on the surfaces of the Al sheets which constitute the liquid flow tubes 2. Al is used as the essential component and the silicon is incorporated at 9.0 to 13.0wt.% therein as the brazing filler metals to be clad on the surfaces of the Al sheets which constitute the seat plates 5 and a tank 6. The respective members, liquid flow tubes 2, seat plates 5 and tank 6, made of the Al sheets coated with these brazing filler metals are tentatively assembled and the assembly is heated and brazed in a heating furnace. The good brazing of the respective members is possible in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The aluminum heat exchanger according to the present invention is used as a radiator for dissipating heat from cooling water of an automobile engine, a heater core for heating, or the like.

(Prior Art) For example, a heat exchanger 1 as shown in FIG. 1 is used as a radiator for radiating heat from cooling water of an automobile engine.

This heat exchanger 1 includes a large number of liquid passage pipes 2.2 and fins 3.3.
Seat plates 5.5 are attached to both ends of the core portion 4 consisting of
This seat plate 5.5 connects the core portion 4 and a pair of tanks 6.
6, and heat exchange is performed between the cooling water flowing through the many liquid passage pipes 2.2 from one tank 6 to the other tank 6 and the air passing through the core part 4. The structure is such that heat from the cooling water is radiated by setting the cooling water.

By the way, when the heat exchanger as described above is made of aluminum alloy, the liquid passage pipes 2.2, fins 3.3, and seat plate 5.5, each made of aluminum alloy, are (
If the tank 6.6 is also made of aluminum alloy, it is necessary to braze the tank 6.6 in a liquid-tight manner.

For this reason, as disclosed in, for example, Japanese Unexamined Patent Publication No. 59-44593, each of the above-mentioned members 2, 3, and 5 has been coated with silicon (Si) on the surface of an aluminum alloy core material.
The above-mentioned members 2.3.5, which are coated with an aluminum alloy brazing material containing a large amount of By melting the materials, each member 2.3.5 is joined by brazing, as shown in -a.

(Problem to be Solved by the Invention) However, in the case of a conventional aluminum heat exchanger, the brazing filler metal on the surface of the aluminum plate constituting each member 2.3.5 was made of the same material, for example, JIS 4343 material. As a result, the following inconveniences occurred.

That is, the aluminum plate that constitutes each liquid passage pipe 2.2 and the aluminum plate that constitutes the seat plate 5.5 usually have different plate thicknesses. While the plate thickness is about 0.34 mm, the seat plate 5
．． The thickness of the aluminum plate constituting 5 is about 0.6 mm, which is considerably thicker than the aluminum plate constituting liquid passage pipe 2.2.

In this way, aluminum plates with greatly different thicknesses are
When heated under the same conditions (in a QL heating furnace), there may be a difference in temperature rise.

For example, according to the inventor's experiments, when the temperature inside the heating furnace is suddenly increased,
While the temperature of an aluminum alloy plate with a thickness of about 0.34 mm rose as shown by the solid line a in Figure 3,
The temperature of the aluminum alloy plate with a thickness of about 0.6+nm that forms the seat plate 5.5 rises as shown by the broken line in the figure, and the temperature for normal brazing is 600°C. Even when the temperature was around the same, a temperature difference of about 10 to 20°C arose between the two plate materials. In this way, when a large temperature difference occurs between two types of aluminum alloy plates with different thicknesses, it is inevitable that there will be a difference in the degree of melting of the brazing filler metal coated on the surface of the two plates. Brazing is likely to be defective.

When the temperature rise in the heating furnace is made gradual, the thickness becomes 0.
．． The temperature of an aluminum alloy plate of about 34 mm is
As shown by the solid line C in Figure 4, the thickness increased to 0.
．． The temperature of the aluminum alloy plate material of about 6mm+ is
As shown by the broken line d in the same figure, the temperature difference between the two plates is only around 5°C at maximum, even near the melting temperature of the brazing metal, and the two plates can be brazed well. However, if the temperature rise in the heating furnace is slowed down, brazing will take a long time, which not only hinders the efficiency of manufacturing work but also increases the overall length of the furnace in the case of a continuous furnace. This may lead to an increase in the size of the equipment.

In the aluminum heat exchanger of the present invention, the brazing filler metal coated on the surface of the aluminum plate for configuring the liquid passage pipes is different from the brazing filler metal coated on the surface of the aluminum plate for configuring the seat plate. This solves the above-mentioned inconvenience.

(Means for Solving the Problems) The aluminum heat exchanger of the present invention, like the conventional aluminum heat exchanger described above, is made of a first aluminum plate whose surface is coated with a first brazing filler metal. The end of the liquid tube is coated with a second brazing material on the surface and is brazed to a seat plate made of a second aluminum plate that is thicker than the first aluminum plate.

Furthermore, in the aluminum heat exchanger of the present invention, the first brazing filler metal contains aluminum as a main component and silicon in an amount of 6.8 to 8.2% (the mixing ratio is shown in the specification). (In all cases, all percentages are by weight.) As an aluminum alloy containing
The second brazing filler metal is an aluminum alloy containing aluminum as a main component and 9.0 to 13.0% silicon.

(Function) In the case of the aluminum heat exchanger of the present invention configured as described above, the melting temperature of the second brazing filler metal containing a large amount of silicon is equal to the melting temperature of the first brazing filler metal containing a small amount of silicon. The optimum brazing temperature will be lower accordingly.

For this reason, the temperature in the heating furnace rose rapidly, and as a result, the temperature rise of the second aluminum plate, which was relatively thick, was slower than the temperature rise of the first aluminum plate, which was thinner. Even in this case, the second brazing filler metal that coats the surfaces of both the second aluminum plates melts out in the same way, and the brazing between the first and second aluminum plates is performed well. .

(Experimental Example) Next, an experiment conducted to confirm the effects of the present invention will be described.

In each experiment, as shown in Fig. 2, after temporarily assembling the liquid passage pipe 2, seat plate 5, and tank 6, which are all made of aluminum alloy plates, these members 2.5 .6 was heated in a heating furnace to perform brazing, and the brazing was performed by visually observing the quality of the properties.

The inside of the heating furnace was a nitrogen atmosphere with a dew point of 130° C. or less, and the inside of this heating furnace was heated to 620° C. in a predetermined period of time.

Each of the above members 2.5.6 is a core material J
IS 3003 material (Si: 0.6% or less, Fe: 0°7
% or less, Cu from 0.05 to 0.20%, Mn from 1°o to
10% on the surface of an aluminum alloy containing 0.10% or less of Zn and the remainder being AI and unavoidable impurities.
The thickness of the aluminum plate constituting the liquid flow pipe 2 is 0.34 mm, and the thickness of the aluminum plate is 0.34 mm, and the thickness of the aluminum plate is 0.34 mm. The thickness of the aluminum plate constituting 6 and 6 is 0, respectively.
．． It was set to 6 mm.

In addition, the flux to be applied to the parts to be brazed is as follows:
I used Nocolok Flux (trade name).

a, Example 1 As a brazing material covering the surface of the aluminum plate constituting the liquid flow pipe 2, the optimum brazing temperature is J
IS 4343 material (St 6.8~8.2%, Fe 0
．． 8% or less, Cu 0.25% or less, Mn 0.10%
Hereinafter, an aluminum alloy containing 0.20% or less of Zn and the rest being ^l as unavoidable impurities is used as the seat plate 5 and the tank 6.
As a brazing material that covers the surface of the aluminum plate that makes up the
4045 material (St: 9°0~13.0%, Fe: 0.8%)
% or less, Cu 0.30% or less, Mn 0.05% or less, Mg 0.05% or less, Zn 0.10% or less,
An aluminum alloy with At and unavoidable impurities as the remainder was used, respectively.

Each member 2 made of aluminum plate coated with these brazing materials
．． 5.6 was temporarily assembled into the state shown in Fig. 2, heated and brazed in a heating furnace for 15 minutes, and each member 2.
5.6 was successfully brazed.

b, Example 2 JIS 4343 material was used as the brazing material to cover the surface of the aluminum plate that constitutes the liquid passage pipe 2, and JIS 404 material was used as the brazing material to cover the surface of the aluminum plate that constituted the seat plate 5.
5 is used as a brazing material to cover the surface of the aluminum plate that constitutes the tank 6, and the optimum brazing temperature is JIS 404.
JIS 4047 material (Si 11.
0 to 13.0%, Fe 0.8% or less, Cu 0.30%
%, Mn was 0.15% or less, Mg was 0.810% or less, Zn was 0.20% or less, and the remainder was unavoidable impurities.

Each member 2 made of aluminum plate coated with these brazing materials
．． 5.6 was temporarily assembled, heated and brazed in a heating furnace for 14 minutes, and each member 2.5.6 was successfully brazed.

C1 Comparative Example 1 JIS4343 material was used as the brazing material covering the surfaces of the aluminum plates constituting the liquid passage pipe 2, the seat plate 5, and the tank 6.

Each member 2 made of aluminum plate coated with these brazing materials
．． 5.6 was temporarily assembled, heated and brazed in a heating furnace for 15 minutes, and defects in brazing occurred at multiple locations at the joint between the liquid passage pipe 2 and the seat plate 5.

d. Comparative Example 2 JIS4045 material was used as the brazing material covering the surfaces of the aluminum plates constituting the liquid passage pipe 2, the seat plate 5, and the tank 6.

Each member 2 made of aluminum plate coated with these brazing materials
．． 5.6 was temporarily assembled, heated and brazed in a heating furnace for 15 minutes, and a part of the liquid passage pipe 2 was cracked.

e. Comparative Example 3 JIS4343 material was used as the brazing material covering the surfaces of the aluminum plates constituting the liquid passage pipe 2, the seat plate 5, and the tank 6.

Each member 2 made of aluminum plate coated with these brazing materials
．． 5.6 was temporarily assembled, heated and brazed in a heating furnace for 20 minutes, and each member 2.5.6 was successfully brazed.

These Examples 1 to 2 and Comparative Examples 1 to 3 are shown in the attached table, and as is clear from these five experimental examples in total, good brazing could not be achieved without taking a long time in the past, but this In the case of the invention, it becomes possible to perform good brazing in a short time.

(Effects of the Invention) As described above, the aluminum heat exchanger of the present invention can successfully braze each 4° part even if the time required for brazing is short, making it easier to manufacture the heat exchanger. It is possible to improve efficiency, reduce heat energy required during manufacturing, and downsize manufacturing equipment, and it is possible to provide an inexpensive aluminum heat exchanger.

[Brief explanation of drawings]

Fig. 1 is a schematic front view showing an example of an aluminum heat exchanger to which the present invention applies, Fig. 2 is an enlarged sectional view of section A in Fig. 1, and Fig. 3 is a case in which the temperature is rapidly increased. FIG. 4 is a diagram showing the temperature rise of the liquid passage pipe and the seat plate, respectively, when the temperature is gradually increased. 1: Heat exchanger, 2: Liquid pipe, 3: Fin, 4: Core part,
5: Seat board, 6: Tank. Patent applicant: Calsonic Co., Ltd. Director: Kinzo Koyama (one idiot) Figure No.? (Fig. Special Ran C)

Claims (1)

[Claims] (1) The end of a liquid passage tube made of a first aluminum plate whose surface is coated with a first brazing filler metal is connected to a second aluminum plate whose surface is coated with a second brazing filler metal and which is thicker than the first aluminum plate. In an aluminum heat exchanger that is brazed to a seat plate made of an aluminum plate, the first brazing material is made of aluminum containing aluminum as a main component and 6.8 to 8.2% by weight of silicon. An aluminum heat exchanger, characterized in that the second brazing material is an aluminum alloy containing aluminum as a main component and 9.0 to 13.0% by weight of silicon.