Heat exchange – Tubular structure
Reexamination Certificate
2001-07-05
2002-08-13
Flanigan, Allen (Department: 3743)
Heat exchange
Tubular structure
C029S890053
Reexamination Certificate
active
06431265
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flat heat-exchange tube for use with a condenser, an evaporator, a heater core, and a radiator each of which is employed in an automotive air-conditioner for effecting a refrigerating operation, as well as to a method of manufacturing the flat heat-exchange tube. More specifically, the present invention relates to a heat-exchange tube in which a plurality of protuberances are formed so as to protrude inwardly.
The present application is based on Japanese Patent Applications No. Hei. 11-11113 and 11-22771, which are incorporated herein by reference.
2. Description of the Related Art
As shown in
FIGS. 15 and 16
, a known flat heat-exchange tube is formed from a plate
1
in which a plurality of beads
1
A are formed so as to protrude to one side of the plate and a plate
2
in which a plurality of beads
2
A are formed so as to protrude to one side of the plate. Specifically, the flat heat-exchange tube is formed by assembling the plates
1
and
2
such that the tops of the beads
1
A and the tops of the beads
2
A are connected together by means of brazing.
Another type of known flat heat-exchange tube is shown in FIG.
17
. As shown in the drawing, the heat-exchange tube is formed by folding a single plate
4
into a flat tube, bonding opposite ends
4
A,
4
A of the plate
4
, and inserting an inner fin
5
into the internal space of the flat tube.
FIG. 18
shows a still another type of a known flat heat-exchange tube. A flat heat-exchange tube A is described in Japanese Patent Publication No. Hei. 7-19774. The flat heat-exchange tube A comprises a flat main tube unit B through which a heat-exchange medium flows, and a plurality of cylindrical beads D which connect tube surfaces C, C, both mutually opposing within the main tube unit B, and cause turbulence in the flow of the heat-exchange medium. Reinforcement protuberances E are formed between a U-shaped bend portion B
1
of the heat-exchange tube A and the main tube unit B, to thereby connect the tube surfaces C, C to the bend B
1
in the longitudinal direction of the main tube unit B and to reinforce the bend B
1
.
In the flat tube A, a heat-exchange medium flowing through the main tube unit B is circulated while the plurality of beads D cause turbulence in the laminar flow of the heat-exchange medium, thereby improving a heat exchange efficiency.
Aforementioned known flat heat-exchange tubes have encountered the following problems.
In the flat heat-exchange tube shown in
FIG. 15
, when the plates
1
and
2
are brought into contact with each other, joints
3
which protrude from either side of the plates
1
and
2
in the widthwise direction thereof become deformed, as shown in
FIG. 16
, thus causing a brazing failure. Further, since the joints
3
protrude from the plates
1
and
2
in the widthwise direction thereof, the widthwise length of the heat-exchange tube becomes longer. The diameter of an unillustrated header pipe to which the flat heat-exchange tube is to be mounted becomes larger correspondingly.
In the flat heat-exchange tube shown in
FIG. 17
, the pressure applied to the joints of the plate
4
is made insufficient when the inner fin
5
is inserted into the internal space and becomes displaced, thus becoming more likely to cause a brazing failure.
In the flat heat-exchange tube A shown in
FIG. 18
, the plurality of beads D cause substantially two-dimensional turbulence in the laminar flow of the heat-exchange medium, and hence the thus-generated turbulence has a little effect of causing turbulence in a thermal boundary layer of heat-exchange medium developing in the vicinity of the tube surfaces C, C, thus limiting an improvement in heat exchange efficiency.
SUMMARY OF THE INVENTION
The present invention is aimed at providing a flat heat-exchange tube which can firmly fix joints and has a narrow width.
The present invention is also aimed at providing a flat heat-exchange tube which can improve heat exchange efficiency than does a known flat heat-exchange tube.
According to a first aspect of the present invention, there is provided a flat heat-exchange tube comprising: a plate of which opposite side edges are folded into a flat tube shape and joined together so as to constitute a flow space for a heat-exchange medium; and a plurality of beads being formed so as to protrude inwardly from one of or both of mutually-opposed flat surface portions of the plate, tops of the beads being joined to corresponding areas on the flat surface portion, wherein a first side edge of the opposite side edges is located on an inner side of a second side edge of the opposite side edges, and joined to the top of the bead located opposite the first side edge.
A height of the bead opposing. the first side edge may be set to be lower than a height of the bead located so as not to oppose the first side edge.
Preferably, the height of the bead opposing the first side edge is set to be lower than the height of the bead located so as not to oppose the first side edge by a thickness of the plate.
The beads can be formed in a plurality of rows in a longitudinal direction of the flat surface portion. An area where the opposite side edges are joined together may be located opposite over a plurality of rows of the beads.
According to a first aspect of the present invention, there is provided a method of manufacturing a flat heat-exchange tube comprising steps of: forming a plurality of beads in one surface portion of a plate so as to protrude from the surface portion; folding the plate into a flat tube shape such that the beads protrude to an inside of the flat tube; bringing side edges of the plate into contact with each other; bringing a joint where the side edges are contacted into contact with a top of the beads; and fixing the joint and a contacted portion of the beads.
The joint may be formed so as to be located within one of the two mutually-opposed flat surface portions of the plate.
The above manufacturing method preferably further comprises a step of forming a stepped portion having a height corresponding to a thickness of the plate on one side edge for fittingly receiving the other side edge at the step of bringing side edges, to thereby make an exterior peripheral surface of the plate including the joint plane, wherein a height of the bead opposing the joint is set to be lower than a height of the bead located so as not to oppose the joint by an amount smaller than the thickness of the plate prior to the fixing step.
According to a third aspect of the present invention, there is provided a flat heat-exchange tube comprising: a flat main tube body through which a heat-exchange medium flows; a plurality of beads for connecting tube surfaces both mutually opposing within the main tube body, to thereby cause turbulence in a flow of the heat-exchange medium within the main tube body; lands being provided between the beads and protruding from al least one tube surface toward an inside of the main tube body; and flow gaps through which the heat-exchange medium flows over the lands.
Preferably, the lands cross-link the beads.
Preferably, beads are intermittently arranged in the main tube body with a plurality of rows in a longitudinal direction of the main tube unit, and the beads of a certain row and the beads of another adjacent row are arranged in a staggered configuration, and the lands are formed between all the beads of the adjacent rows such that a bead of the certain row is linked to the beads of the adjacent rows located in upstream positions with respect to a flow of the heat-exchange medium as well as to the beads of the adjacent rows located in downstream positions with respect to the flow of the heat-exchange medium.
On the other hand, the lands can formed between all the beads of adjacent rows such that a bead of a certain row is linked to one of the beads of the adjacent rows located in upstream positions with respect to a flow of the heat-exchange medium as well as to one of the beads of the adjacent rows located in downstr
Hiyama Junichi
Ishiwa Enichi
Kaneko Shinya
Koga Yoshiaki
Sasaki Yoshihiro
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