Method for manufacturong heat exchanger

Abstract

Low melting point metal such as Zn is sprayed onto a flat surface (3a) of an aluminum flat tube (3) to form a sprayed metal coating (15) thereon inmediately after extrusion of the flat tube. Inmediately thereafter, a brazing foil (11) is integrally adhered onto the sprayed metal coating (15). The obtained flat tube (3) with the brazing foil is combined with a corrugated fin (4) to form a temporary assembly. Then, the temporary assembly is heated at a predetermined temperature to braze the tube (3) and the fin (4) to thereby form a heat exchanger core. The low melting point metal may be sprayed on both the flat surface (3a) of the flat tube and the surface of the brazing foil (11). Thus, it becomes possible to obtain a lightweight thin fin and to decrease material costs.

Description

[0001] This application is an application filed under 35 U.S.C. .sctn.111(a) claiming the benefit pursuant to 35 U.S.C. .sctn.119(e)(1) of the filing data of Provisional Application No. 60 / 301,848 filed on Jul. 2, 2001 pursuant to 35 U.S.C. .sctn.111(b).[0002] The present invention relates to a method for manufacturing a heat exchanger made of aluminum or its alloys (hereinafter simply referred to as "aluminum") such as a condenser, an evaporator and the like for use in automobile, household or office air-conditioning systems.[0003] There is a heat exchanger having a heat exchanging core in which fins are disposed between the adjacent heat exchanging tubes. FIG. 1 shows the so-called parallel flow type heat exchanger. In the heat exchanger, a plurality of flat tubes as heat exchanging tubes are disposed in parallel between a pair of parallel headers 1 and 2 with the opposite ends thereof connected to the headers 1 and 2 in fluid communication. Between these flat tubes 3, corrugated ...

AI Technical Summary

Benefits of technology

[0013] According to the aforementioned former and latter manufacturing methods, the brazing foil which carries out the joining of the aluminum flat tube and the fin constituting a heat exchanging core is adhered to the flat tube whose surface area is much smaller than that of the fin. Furthermore, it is not necessary to attach the brazing foil to the entire surface of the flat tube, but enough to attach the brazing foil to a certain width of the flat tube so that a prescribed joining strength can be secured. Accordingly, as compared with the cases where brazing materials are applied to a fin, the amount of brazing materials decreases greatly as a whole, resulting in reduced material costs. Furthermore, since there is no concern about deformation and / or breaking of the fin by the erosion thereof due to the brazing materials at the time of brazing the flat tube and the fin, a thin member can be used as the fin. In addition to the decreased amount of brazing materials, this can greatly contribute to reduce the weight of the whole heat exchanger, and can avoid poor dimension and / or poor appearance of the heat exchanger due to deformation of the fin.

[0033] As shown in FIG. 2, in the heat exchanger according to the present invention, the alternatively disposed flat tubes 3 and corrugated fins 4 are brazed by the materials of the brazing foils 11 adhered to both the upper and lower flat surfaces of each flat tube 3. Each flat tube 3 is an aluminum extruded hollow article having longitudinally extending partition walls 31 by which the inner space thereof is partitioned into a plurality of passages 32. The corrugated fin 4 is an aluminum bare member with no clad brazing material. The flat tube 3 and the corrugated fin 4 have almost the same width. In the aforementioned structure, the brazing foil 11 to be used for brazing the flat tube 3 and the corrugated fin 4 is adhered to the flat tube 3 having a surface area much smaller than that of the corrugated fin 4, and is not adhered to the lateral sides of the flat tube 3. Furthermore, the brazing foil 11 is provided only to the minimum width of the upper and lower flat surfaces 3a and 3a so as to secure a prescribed joining strength. Accordingly, as compared with the cases where brazing materials are applied to the corrugated fin 4, the amount of brazing materials greatly decreases as a whole, resulting in greatly decreased material costs. Furthermore, since the corrugated fin 4 will not be deformed by the erosion due to the brazing material's at the time of brazing the flat tube 3 and the corrugated fin 4, a thinner corrugated fin 4 can be used without causing any problem. Thus, in addition to the decreased amount of brazing materials as mentioned above, the weight of the heat exchanger can be decreased as a whole.

Problems solved by technology

However, the total joining area of the portions to be joined is very small and that brazing materials are provided on the entire surface of the fin.

Accordingly, excessive brazing materials are consumed, resulting in increased material costs and increased weight.

Furthermore, at the time of brazing in a brazing furnace, the base metal of the fin may be eroded by the brazing materials, causing deformation thereof.

Since this deformation should be prevented, it was difficult to reduce the thickness of the base metal, resulting in increased fin weight, which in turn makes it difficult to reduce the weight of the heat exchanger.

On the other hand, according to the method in which powder-brazing materials are supplied to joining. portions of the flat tubes and the fins to form a brazing coating, it takes a time to apply the brazing materials.

Furthermore, it is difficult to control the grain size and the thickness of the coating, resulting in uneven thickness of the coating, which in turn causes poor joined portions, partial erosion, etc.

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