Metal working – Method of mechanical manufacture – Heat exchanger or boiler making
Reexamination Certificate
1999-04-27
2001-08-07
Rosenbaum, I Cuda (Department: 3726)
Metal working
Method of mechanical manufacture
Heat exchanger or boiler making
C029S890045, C029S890047
Reexamination Certificate
active
06269541
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat exchanger having tubes through which fluid passes and corrugated fins.
2. Description of Related Art
Conventionally, tubes and fins are joined with each other by brazing material covering (clad) the surface of the tubes or fins.
However, the tubes or fins covered by the brazing material are high in manufacturing cost. Furthermore, if the fin is covered by the brazing material, the heat exchanging performance of the heat exchanger is reduced due to diffusion effect of the brazing material at the heating of the brazing process.
Further, if the thickness of the tubes and the fins is reduced to improve the heat exchanging performance, a problem may be noticeable that erosion occurs in the tube or fin due to the diffusion effect of the brazing material.
To solve these problems, it may be possible to spread brazing material, in form of paste, powder, solid or the like, only on contact portions of fin or tube. However, as the tube interval (the difference in size between the peak and the valley of the fin) increases by the thickness of the spread brazing material, it is difficult to, for example, insert and assemble the tubes into a header tank (core plate), thereby compromising the assembly of fins, tubes and the like and reliability of brazing between the fins and the tubes.
Further, according to the above method, the brazing material is rubbed and may be easily removed when the tubes and the fins are combined.
SUMMARY OF THE INVENTION
The present invention is made in light of the foregoing problems, and it is an object of the present invention of provide a heat exchanger which can improve its assembling operability and heat exchanging performance.
According to the heat exchanger of the present invention, a fin has bent portions and a hole formed through the bent portions, and the fin and tubes are brazed by brazing material spread on the inside of bent portions of the fin.
That is, the tubes and the fin are brazed by the brazing material spread on the inside of the bent portions of the fin, as the brazing material melts upon heating in brazing process and leaks through the hole to the outside of the bent portions. Accordingly, the tubes and the fins can be easily piled and assembled without increasing the tube interval. Accordingly, the assembling operability of the heat exchanger is improved, and the tubes and the fin can be reliably brazed with each other.
Further, since the brazing material remains mainly around the bent portions, most parts of the fin and the tubes are not covered with the brazing material. Thus, there is no diffusion effect, and the heat exchanging performance of the heat exchanger is improved, and the occurrence of the erosion is prevented even if the thickness of the fin and the tubes is reduced.
Further, because it is not necessary to coat the entire surface of the tubes and the fins with the brazing material, the required amount of the brazing material can be reduced to a minimum amount. Therefore, increase in costs regarding these materials is prevented. As a result, the manufacturing cost for the heat exchanger is reduced.
REFERENCES:
patent: 3693710 (1972-09-01), Drosnin
patent: 4626295 (1986-12-01), Sasaki et al.
patent: 4843693 (1989-07-01), Chisholm
patent: 5005285 (1991-04-01), Ishii
patent: 5685075 (1997-11-01), Kato
patent: 053 452 (1982-06-01), None
patent: 0 546 334A1 (1993-06-01), None
patent: 574949 (1946-01-01), None
patent: A-6-170520 (1994-06-01), None
patent: A-7-32133 (1995-02-01), None
Hirakami Koji
Iguchi Takeshi
Kotate Homare
Uchikawa Akira
Cuda Rosenbaum I
Denso Corporation
Harness Dickey & Pierce PLC
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