Heat exchange – Side-by-side tubular structures or tube sections – With manifold type header or header plate
Reexamination Certificate
1999-02-05
2001-04-17
Flanigan, Allen (Department: 3743)
Heat exchange
Side-by-side tubular structures or tube sections
With manifold type header or header plate
C165S110000, C165S174000, C165S177000
Reexamination Certificate
active
06216776
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application relates to and claims priority from Japanese Patent Application No. Hei. 10-32505 filed on Feb. 16, 1998, No. Hei. 10-65719 filed on Mar. 16, 1998, No. Hei. 10-95961 filed on Apr. 8, 1998, No. Hei. 10-168700 filed on Jun. 16, 1998, and No. Hei. 10-294163 filed on Oct. 15, 1998, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat exchanger which is typically applied to a condenser or a radiator for a refrigerant cycle in which carbon dioxide is used as refrigerant.
2. Related Art
Recently, refrigerant cycles without using chlorofluorocarbon (hereinafter referred to as flon) as refrigerant are developed to prevent global warming. A super critical refrigerant cycle in which carbon dioxide (CO
2
) is used as refrigerant (hereinafter referred to as CO
2
refrigerant cycle) is studied. However, because the CO
2
refrigerant cycle has a high operation internal pressure, heat exchangers used in the CO
2
refrigerant cycle, such as a condenser into which high-pressure refrigerant flows, need to have a high strength. As shown in
FIG. 38
, JP-A-5-215482 discloses a heat exchanger having plural extruded flat tubes
302
. Each of the flat tubes
302
has plural fluid passages
302
a
having a round-shaped cross-section, so that strength of each flat tube
302
is improved. However, since each fluid passage
302
a
has the round-shaped cross-section, a wall thickness of the flat tube
302
becomes thicker as compared with a flat tube having fluid passages with a square-shaped cross-section. As a result, weight of each flat tube
302
is increased. On the other hand, when the flat tube has the fluid passages having the square-shaped cross-section, wall thickness and weight of the flat tube are decreased, but strength of the flat tube is also decreased.
On the other hand, JP-A-2-247498 discloses a heat exchanger in which an inner supporting plate is disposed within a header tank having first and second plates, so that strength of the header tank is enhanced. However, in the heat exchanger, the inner supporting plate and the header tank are connected to each other by an acute angle, and stress tends to be intensively applied to a connection portion between the inner supporting plate and the header tank. As a result, the strength of the heat exchanger may be not resistant to high pressures such as 40 MPa of the CO
2
refrigerant cycle.
Further, JP-A-3-260596 discloses a conventional heat exchanger having plural flat tubes
402
through which refrigerant flows, and a pair of substantially cylindrical header tanks
405
connected to both longitudinal ends of the flat tubes
402
, as shown in FIG.
39
. However, high pressure of the CO
2
refrigerant cycle is approximately ten times larger than that of a refrigerant cycle using flon as refrigerant. Therefore, when the conventional heat exchanger is used in the CO
2
refrigerant cycle, thickness of the header tank
405
may need to be greatly increased so that the header tank
405
has a sufficient pressure resistance. As a result, size and weight of the header tank
405
may be increased.
SUMMARY OF THE INVENTION
In view of the foregoing problems, it is a first object of the present invention to provide a heat exchanger having relatively light weight and high strength.
It is a second object of the present invention to provide a heat exchanger having large pressure resistance.
It is a third object of the present invention to provide a heat exchanger in which refrigerant is introduced into tubes from each tank passage of a header tank so that heat-exchange performance of the heat exchanger is improved.
It is a fourth object of the present invention to provide a heat exchanger in which an amount of refrigerant introduced into tank passages of the header tank is controlled so that heat-exchange performance of the heat exchanger is improved.
According to the present invention, a heat exchanger includes a plurality of tubes and a header tank disposed on each longitudinal ends of the tubes. Each of the tubes has a first portion having a first wall portion for forming plural first passages through which a fluid flows, and a second portion disposed on each sides of the first portion. The second portion has a second wall portion for forming a second passage in which no fluid flows. Each of longitudinal ends of the second portion is recessed from each of the longitudinal ends of the first portion, and the second wall portion has a wall thickness thinner than that of the first wall portion. Therefore, a cross-sectional area of the second passage is increased, while a cross-sectional area of the second wall portion is decreased. Thus, weight of each tube is decreased while strength of each tube is improved.
Preferably, the first passage of the first portion has a round-shaped cross-section, and the second passage has a polygonal-shaped cross-section. Therefore, each of the tubes has a sufficient strength, while weight thereof is reduced.
More preferably, the header tank has therein an inner partition wall extending in a longitudinal direction of the header tank to partition an inner space of the header tank into first and second tank passages. A width of the inner partition wall in a width direction perpendicular to both of a longitudinal direction of the tubes and the longitudinal direction of the header tank is gradually increased toward inner walls of the header tank, so that the first and second tank passages have an oval-shaped cross-section. As a result, pressure resistance of the header tank is improved.
Further, the first tank passage is provided on an upstream air side of the second tank passage relative to a flow direction of air passing through between the tubes, and an amount of the fluid flowing through the first tank passage is made larger than an amount of the fluid flowing through the second tank passage. As a result, more fluid flows through the tubes at an upstream air side, thereby improving heat-exchange performance of the heat exchanger.
Preferably, the header tank has a first communication hole through which the first and second tank passages communicate with each other, and a second communication hole through which the first tank passage communicates with a pipe for introducing the fluid into the header tank. An opening area of the first communication hole is set to smaller than that of the second communication hole, so that more fluid flows through the first tank passage than the second tank passage. Thus, heat-exchange performance of the heat exchanger can be further improved.
REFERENCES:
patent: 5190101 (1993-03-01), Jalelivand et al.
patent: 5236045 (1993-08-01), Janezich et al.
patent: 5479985 (1996-01-01), Yamamoto et al.
patent: 5941303 (1999-08-01), Gowan et al.
patent: 61-202084 (1986-09-01), None
patent: 63-3191 (1988-01-01), None
patent: 1-217195 (1989-08-01), None
Kobayashi Osamu
Mitsukawa Kazuhiro
Yamamoto Ken
Yamauchi Yoshiyuki
Denso Corporation
Flanigan Allen
Harness Dickey & Pierce PLC
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