Heat exchanger having multi-hole structured tube

Details Heat exchanger having multi-hole structured tube Heat exchanger having multi-hole structured tube

2000-05-25

2002-01-22

Bennett, Henry (Department: 3743)

Heat exchange

Side-by-side tubular structures or tube sections

With manifold type header or header plate

C165S153000, C165S175000

Reexamination Certificate

active

06340055

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of Japanese Patent Applications No. 11-145323 filed on May 25, 1999, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to heat exchangers suitable for a radiator, an evaporator, or the like in a refrigerating cycle.
2. Description of the Related Art
JP-A-1-351783 proposes a heat exchanger in which, as shown in
FIG. 15A
, notch portions
211
a
indicated with slant lines are provided at both long-side end portions of a tube
211
to reduce a size of the heat exchanger in a direction parallel to an air flow direction.
On the other hand, as shown in
FIG. 15B
, a tube
211
, which is generally used at a high internal pressure state for a heat exchanger such as a condensers a radiator, or a heat exchanger of a super critical refrigerating cycle, adopts a multi-hole structure having several passage holes
211
b
arranged in the cross-sectional long-side direction thereof, thereby improving a withstand pressure of the tube
211
. The super critical refrigerating cycle uses refrigerant such as carbon dioxide, ethylene, ethane, or nitrogen oxide, a pressure of which exceeds a super critical pressure.
SUMMARY OF THE INVENTION
However, it has been revealed by the inventors that the following problems were liable to occur when the structure proposed in JP-A-11-351783 was applied to the tube
211
having the multi-hole structure. Specifically, the passage holes
211
b
are formed at the same time when the tube
211
is formed by extrusion molding or the like. If the notch portions
211
a
are formed on the tube
211
by cutting after the passage holes
211
b
are formed, as shown in
FIG. 16A
, the cut surface is liable to be crushed at a vicinal region of the passage holes
211
b
. When the cut surface is crushed to form a crushed portion
160
and the tube
211
is inserted into a header tank with the crushed portion
160
, the crushed portion
160
forms a space between the tube
211
and the header tank, and the space induces joining failure (welding failure) therebetween readily. Further, if the tube
211
has manufacture variations when it is formed and it is cut, as shown in
FIG. 16B
, one of the passage holes
211
b
may be cut. The cut hole
211
b
forms a space (gap), which can induce the joining failure between the tube
211
and the header tank readily.
The present invention has been made in view of the above problems. An object of the present invention is to prevent joining failure between a multi-hole structured tube and a header tank in a heat exchanger.
According to the present invention, a tube for a heat exchanger has an end portion in a longitudinal direction thereof. The end portion is formed by a cut surface, which extends in the longitudinal direction of the tube and defines an end portion width, which is smaller than a tube width at a portion of the tube other than the end portion. The end portion width and the tube width are perpendicular to the longitudinal direction and parallel to a cross-sectional long side direction of the tube. The tube has a plurality of passage holes arranged in the cross-sectional long side direction within the end portion width, and a hole of the passage holes disposed most adjacently to the cut surface defines a specific distance &dgr;
0
from the cut surface.
Accordingly, the hole and the cut surface can be prevented from being crushed when the cut surface is formed. When the end portion of the tube is inserted into a header tank, no gap is produced between the tube and the header tank, thereby preventing joining failure between the tube and the header tank.


REFERENCES:
patent: A-11-351783 (1999-12-01), None

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