Heat exchange – Three non-communicating fluids
Reexamination Certificate
2000-08-16
2001-04-10
Leo, Leonard (Department: 3743)
Heat exchange
Three non-communicating fluids
C165S135000
Reexamination Certificate
active
06213196
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application relates to and claims priority from Japanese Patent Application No. 11-276941 filed on Sep. 29, 1999, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to heat exchangers, and particularly to a double heat exchanger having plural heat exchange cores. The present invention is suitably applied to a double heat exchanger combining a condenser of a refrigeration cycle for a vehicle air conditioner and a radiator for cooling engine coolant.
2. Related Art
Generally, in a double heat exchanger having plural heat exchange cores, a specification of one of the heat exchange cores does not necessarily conform to a specification of the other. Conventionally, a double heat exchanger has a condenser core and a radiator core in which a corrugated condenser fin and a corrugated radiator fin are integrally formed. In such a heat exchanger, when plural condenser tubes and plural radiator tubes are arranged in a vertical direction at the same pitch and a height of each of the radiator tubes is larger than that of each of the condenser tubes in the vertical direction, a height of the condenser fin disposed between adjacent condenser tubes needs to be larger than that of the radiator fin disposed between adjacent radiator tubes in the vertical direction.
However, since the condenser fin is integrally formed with the radiator fin, a longitudinal length of the condenser fin when flattened to a flat plate is necessarily equal to that of the radiator fin. Therefore, a height of the condenser fin can not be simply increased by increasing only the longitudinal length of the condenser fin.
JP-A-11-148795 discloses a double heat exchanger in which a height of a corrugated radiator fin is made larger than that of a corrugated condenser fin by setting a radius of curvature of each wave of the radiator fin smaller than that of each wave of the condenser fin. However, generally, in a multi-flow type heat exchanger having plural tubes, the tubes and plural fins are alternately layered to be tentatively assembled and then integrally brazed in a furnace. Therefore, when a radius of curvature of each wave of the condenser fin is different from that of the radiator fin, an amount of deformation of the condenser fin caused by a force of constraint applied to the condenser fin during an assembling process of the condenser fin and condenser tubes becomes different from that of the radiator fin, even if the condenser fin and the radiator fin are made of the same material and has the same plate thickness. As a result, a contact pressure between the condenser fin and each of the condenser tubes may be largely different from a contact pressure between the radiator fin and each of radiator tubes, thereby causing a fin-tube brazing failure.
Further, when a radius of curvature of each wave of the fin is decreased, a filler is restricted from being formed at a connection portion between the fin and the tube during brazing. Therefore, an area of heat transfer from the tube to the fin is decreased, thereby declining heat exchange performance of the heat exchanger.
SUMMARY OF THE INVENTION
In view of the foregoing problems, it is an object of the present invention to provide a heat exchanger having first and second heat exchangers, in which a first corrugated fin of the first heat exchanger is integrally formed with a second corrugated fin of the second heat exchanger while a radius of curvature of each wave of the first fin is not largely different from that of the second fin.
According to the present invention, a heat exchanger has a first heat exchanger and a second heat exchanger disposed at a downstream air side of the first heat exchanger. The first heat exchanger has a plurality of first tubes through which a first fluid flows and a first fin disposed between adjacent first tubes to facilitate heat exchange between the first fluid and air. The first fin has a corrugated shape including a plurality of first upper folds, a plurality of first lower folds and a first wall portion which connects one of the first upper folds and one of the first lower folds next to each other. The second heat exchanger has a plurality of second tubes through which a second fluid flows and a second fin disposed between adjacent second tubes to facilitate heat exchange between the second fluid and air. The second tubes extend in substantially parallel with the first tubes. The second fin is integrally formed with the first fin to have a corrugated shape including a plurality of second upper folds, a plurality of second lower folds and a second wall portion which connects one of the second upper folds and one of the second lower folds next to each other. The first and second fins are partially connected to each other through a connection member. An inclination angle of the first wall portion is different from that of the second wall portion so that a height of the first fin becomes different from that of the second fin.
Therefore, a height of the first fin becomes different from that of the second fin while maintaining a radius of curvature of each of the first upper and lower folds of the first fin equal to that of each of the second upper and lower folds of the second fin. As a result, the first fin and the second fin respectively make contact with each of the first tubes and the second tubes with the substantially same contact pressure during an assembling process, thereby restricting a brazing failure between the first and second fins and each of the first and second tubes. Further, according to the present invention, each of the radius of curvature of the first and second fins becomes a relatively large value. Therefore, a fillet is sufficiently formed between the first and second fins and each of the first and second tubes, respectively, during a brazing process, and a heat exchange performance of the heat exchanger is restricted from declining.
REFERENCES:
patent: 5172752 (1992-12-01), Goetz, Jr.
patent: 5992514 (1999-11-01), Sugimoto et al.
patent: 11-148795 (1999-06-01), None
Kachi Kenichi
Ozaki Tatsuo
Sakane Takaaki
Denso Corporation
Harness Dickey & Pierce PLC
Leo Leonard
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