Information
-
Patent Grant
-
6267177
-
Patent Number
6,267,177
-
Date Filed
Wednesday, January 19, 200024 years ago
-
Date Issued
Tuesday, July 31, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 405 166
- 405 177
- 029 890053
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International Classifications
-
Abstract
The height of a bead opposing a joint where side edges of a plate are to be joined is set to be smaller than the height of a bead which does not oppose the joint by the thickness of the plate. Further, lands are provided between the beads and protrude from either the tube surface or the tube surface toward the inside of the main tube unit, and flow gaps are formed through which the heat-exchange medium flows over the lands.
Description
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 an 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 rube 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
or 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 or the heat-exchange medium, and hence the thus-generated turbulence has a little affect of causing turbulence in a thermal boundary layer of hear-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 downstream positions with respect to the flow of the heat-exchange medium, to thereby linearly link the beads.
The beads can be arranged at uniform intervals in the longitudinal direction of the main tube body, and the beads of a certain row and the beads of another adjacent row can be arranged in a staggered configuration.
The lands may be formed so as to have a circular-arc cross section.
In the present invention, the height of a bead located opposite one side edge of a plate is set to be lower than the height of another bead located so as not to oppose the side edge. Therefore, a joint where both side edges of the plate meet and are joined can be prevented from raising outwardly from the exterior side surface of the plate. Further, the joint of the plate is formed in a flat surface portion of the plate opposing the beads, thereby preventing an undesired increase in the width of a flat heat-exchange tube.
The joint where the side edges of the plate meet and are joined can be made in flush with the exterior side surface of the plate, thus preventing the joint from raising from the exterior side surface of the flat heat-exchange tube. Further, beads located so as not to oppose the joint can be joined to corresponding areas on the flat surface portion of the plate unfailingly.
The joint where the side edges of the plate meet and are joined can be connected to the tops of the row of beads formed in the flat surface portion(s) in the longitudinal direction thereof, thus forming a firmly-connected joint over the plate in the longitudinal direction thereof and ensuring a joint strength.
The joint where the side edges of the plate meet and are joined are joined to a plurality of rows of beads, thus increasing the bonding strength of the joints to a much greater extent.
The joint where the side edges of the plate meet and are joined and the joint and the tops of the beads can be brought into contact with each other and fixed together by a single operation. The joint and the tops of the beads can be brought into contact with each other by pressing the joint formed between the side edges of the plate, thus facilitating manufacture of a flat heat-exchange tube.
The joint where the side edges of the plate meet and are joined is placed within the flat surface portion of the plate, thus preventing an increase in the width of the flat heat-exchange tube. Accordingly, there can be prevented an increase in the diameter of a pipe to which the flat heat-exchange pipe is to be mounted.
A step having a height corresponding to the thickness of the plate is formed in one of the side edges of the joint, thus preventing the joint from raising outwardly, which would otherwise be caused when the side edges are joined. The height of beads located opposite the joint is set beforehand to be lower than the height of beads located so as not to oppose the joint, by only the height of the plate. Accordingly, when the plate is folded, the joint where the side edges of the plate meet can be situated on and brought into pressing contact with the tops of the beads, thus forming contacts unfailingly. Further, the tops of the beads located so as not oppose the joint can also be brought into contact with the interior surface of the plate by means of the pressing force, thus achieving formation of contacts and firm brazing unfailingly.
Further, in the present invention, a heat-exchange medium flows over lands while the laminar flow of the heat-exchange medium is made turbulent by a plurality of beads. The heat-exchange medium flowing over the lands flows down from their tops toward a tube surface, thus causing turbulence in a thermal boundary layer of heat-exchange medium developing in the vicinity of the tube surface. The heat-exchange tube of the present invention can make the thermal boundary layer of the heat-exchange medium thinner than does the known flat heat-exchange tube having only a plurality of beads, thus enabling a further improvement in the heat exchange efficiency.
In the present invention, since the beads are cross-linked by the lands, the heat-exchange medium flowing between the beads can fall down from the tops of the lands toward the tube surface unfailingly. Accordingly, the thermal boundary layer of the heat-exchange medium developing in the vicinity of the tube surface can be made turbulent unfailingly.
In the present invention, all the beads are linked by the lands so as to intersect diagonally with respect to the longitudinal direction of a main tube unit. A plurality of substantially-rectangular regions, each having four sides which are diagonal with respect to the longitudinal direction or the main tube unit, are formed in either one or the tube surfaces In each of the rectangular regions, the thermally boundary layer can be made turbulent. Accordingly, the heat-exchange tube of the present invention can improve a heat exchange efficiency to a greater extent.
In the present invention, all the beads are linked by the lands so as to intersect diagonally with respect to the longitudinal direction of the main tube unit. Consequently, in at least one of the tube surfaces there can be formed alternately land regions—in which the beads are linked by the lands so as to extend diagonally with respect to the longitudinal direction of the main tube unit—and flow regions which extend along the land regions and do not have any lands.
The heat-exchange medium that has flowed over the lands provided in the land regions can cause turbulence in the thermal boundary layer of the heat-exchange medium. Further, the flow regions enable smooth flow of the heat-exchange medium, thus achieving both an improvement in heat exchange efficiency and a reduction in flow resistance.
In the present invention, the beads are arranged at uniform intervals in the longitudinal direction of the main tube unit. The beads of the adjacent rows a rear ranged in a staggered configuration, thus increasing the distribution density of the beads. Consequently, there can be achieved a further increase in heat exchange efficiency and an improvement in compressive strength of the main tube unit.
In the present invention, the land formed has a circular-arc cross section, thus enabling a decrease in the flow resistance which the heat-exchange medium encounters when flowing over the top of the land. Accordingly, the heat-exchange tube or the present invention can diminish flow resistance.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG. 1
is a perspective view showing the principal section of a flat heat-exchange tube according to a first embodiment of the invention;
FIG. 2
is a cross-sectional view showing the principal section of the flat heat-exchange tube of the first embodiment;
FIG. 3
is a perspective view of the principal section of a plate constituting the flat heat-exchange tube of the first embodiment;
FIG. 4
is an exploded perspective and descriptive view showing the flat heat-exchange tube of the first embodiment;
FIG. 5
is a cross-sectional descriptive view showing the principal section of the flat heat-exchange tube of the first embodiment;
FIG. 6
is a cross-sectional descriptive view showing the principal section of the flat heat-exchange tube of the first embodiment;
FIG. 7
is a cross-sectional descriptive view showing the principal section of a flat heat-exchange tube according to a second embodiment of the present invention;
FIG. 8
is a plan view showing a heat-exchange tube according to a third embodiment of the present invention;
FIG. 9
is a cross-sectional view of the heat-exchange tube taken along line V—V shown in FIG
8
;
FIG. 10
is a perspective view showing the principal section of the heat-exchange tube shown in
FIG. 8
;
FIG. 11
is a plan view showing a heat-exchange tube according to a fourth embodiment of the present invention;
FIG. 12
is a perspective view showing the principal section of the heat-exchange tube shown in
FIG. 11
;
FIG. 13
is a plan view showing a heat-exchange tube according to a fifth embodiment of the present invention;
FIG. 14
is a perspective view showing a heat-exchange tube according to a sixth embodiment of the present invention;
FIG. 15
is a descriptive view showing a process for manufacturing a known flat heat-exchange tube;
FIG. 16
is a cross-sectional view of the principal section of a known flat heat-exchange tube for describing a problem thereof;
FIG. 17
is an exploded perspective view showing another example of a known flat heat-exchange tube; and
FIG. 18
is a perspective view showing a still another example of a known heat-exchange tube.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A flat heat-exchange tube according to the present invention will be described in detail hereinbelow by reference to embodiments illustrated in the accompanying drawings.
FIGS. 1 through 6
show a flat heat-exchange tube according to a first embodiment of the present invention
FIG. 1
is a perspective view showing the principal section of a flat heat-exchange tube
11
of a condenser which is employed as an automotive heat exchanger for effecting a refrigerating operation.
As shown in
FIG. 1
, side edges
12
A and
12
B of a single rectangular plate
12
are folded so as to overlap at the center of the plate
12
, thus forming the flat heat-exchange tube
11
. Channels for a heat-exchange medium serving as a coolant are formed within the flat heat-exchange tube
11
. A plate joint where the side edges
12
A and
12
B overlap is jointed to the top surface of a bead
13
protruding from a portion of the plate
12
opposing the plate joint (i.e., the underside portion of the plate
12
). The plate joint between the side edges
12
A and
12
B, the side edge
12
B located inside of the plate joint, and the top surface of the bead
13
are connected by means of brazing.
The beads
13
are intermittently and protruding formed in rows in the surface of the plate
12
along the longitudinal direction (i.e., the direction in parallel with the side edges
12
A and
12
A) of the flat heat-exchange tube
11
. The plate joint is set to be located on each of the rows of beads
13
. Beads
14
are intermittently formed in rows in the area of the underside portion of the plate
12
, which area does not face the plate joint in the longitudinal direction thereof. The row of bead
14
is higher than the row of bead
13
. In the present embodiments two rows of beads
14
are intermittently formed in the plate
12
in the longitudinal direction thereof The beads
13
and
14
are formed by means of dimpling, and the beads
14
are fixed to the portions of the plate
12
opposing the beads
14
by means of brazing.
As shown in
FIG. 2
, The height H
1
of the bead
13
formed in the flat heat-exchange tube
11
of the present embodiment is larger than the height H
2
of the bead
14
by the thickness “t” of the plate
12
. A step is formed in the side edge
12
B which will constitute a plate joint, to a height corresponding to the thickness “t” of the plate
12
. The side edge
12
A is fitted into the step, thus rendering the exterior surface of the plate joint plane. Each of the beads
13
and
14
is circular when viewed from the above and is trapezoidal when viewed in cross section. The beads
13
and
14
complicate and elongate the coolant flow channel and contribute to an increase in the surface area and rigidity of the flat heat-exchange tube
11
. Although not shown in the drawings, an inlet port for permitting inflow of a coolant is formed in one longitudinal end of the flat heat-exchange tube
11
, and an outlet port for permitting outflow of a coolant is formed in the other longitudinal end of the same.
A method of manufacturing the flat heat-exchange tube
11
of the present embodiment will now be described by reference to
FIGS. 3 through 6
. In the present embodiment, the plate
12
, which has already been machined as shown in
FIG. 3
, is folded and subjected to brazing. As shown in the drawing, in the present embodiment, the beads
13
and
14
are formed in an intermediate area of the plate
12
which has a predetermined width and extends in the longitudinal direction of the plate
12
. The side edge on either side of the intermediate area of the plate
12
is folded. A step for fittingly receive the side edge
12
A when the side edges
12
A and
12
B are folded is formed along the edge of the side edge
12
A The beads
13
are intermittently formed in a row along the longitudinal center of the plate
12
, and the beads
14
are formed in a predetermined layout on either side of the row of beads
13
. The number of rows of beads
13
and the number of rows of beads
14
may be changed, as required, according to the size of the flat heat-exchange tube
11
.
The side edges
12
A and
12
B of the plate
12
are folded such that the side edge
12
A is laid on the side edge
12
B, as shown in FIG.
4
.
FIG. 4
is an exploded perspective and descriptive view showing the flat heat-exchange tube
11
when the tube
11
is cut and exploded so as to make the underside portion of the plate
12
visible. In
FIG. 4
, the shaded area denotes the area where a plate joint is to be formed; that is, a position an the beads
13
.
Next will be described the height of the beads
13
and the height of the beads
14
, which are formed in the plate
12
beforehand. As shown in
FIG. 5
, the height H
2
′ of the bead
13
is set beforehand so as to be lower than the height of H
1
of the bead
14
by an amount smaller than the thickness “t” of the plate
12
. Thus, the height H
2
′ of the bead
13
is set slightly higher than a height which is obtained by subtracting the thickness “t” from the height of H
1
of the bead
14
(H
2
′+t>H
1
).
FIG. 5
shows the plate joint (where the side edges
12
A and
12
B overlap) is in contact with the top surface of the bead
13
. At this time, the top surface of the bead
14
is spaced apart from a corresponding portion of the interior surface of the plate
12
.
The plate joint is forcefully pressed against the top surface of the bead
13
by means of predetermined force, thereby bringing the side edge
12
A into contact with the side edge
12
B and bringing the side edge
12
B into contact with the top surface of the bead
13
unfailingly At this time, the height of the bead
13
is reduced to H
2
by means of pressing force. As shown in
FIG. 6
, the interior surface of the plate
12
is also brought into contact with the top surfaces of the beads
14
by means of the pressing force while the side edges
12
A and
12
B, the side edge
12
B and the beads
13
, the beads
14
and the interior surface of the plate
12
are remaining in contact with each other respectively, these portions are fixed by means of brazing, thereby forming the flat heat-exchange tube
11
of the present embodiment.
In the present embodiment, formation of firm joints and reliable brazing can be achieved by setting the height of the beads
13
and the height of the beads
14
in the manner as mentioned previously. The beads
13
and
14
, which have been formed in a layout such as that mentioned above, cause turbulence in the flow of a coolant circulating between the beads
13
and
14
, thus improving heat exchange efficiency.
The plate joint may be formed so as to extend across two rows of beads
13
according to a second embodiment as shown in
FIG. 7
In this case, the pressing force to be applied for bringing the side edges into contact with each other can be made to a greater extent In the above embodiments, the beads are formed to protrude from one flat portion of the plate (i.e, the underside portion of the plate)- Needless to say, beads may be formed so as to protrude from both flat portions of the plate (i.e., both the upper portion and the lower portion of the plate).
FIG. 8
is a plan view showing a third embodiment according to the present invention.
FIG. 9
is a cross-sectional view taken along line V—V shown in FIG.
8
. As shown in
FIGS. 8 and 9
, the heat exchange flat tube
1
comprises a flat main tube unit
22
through which a heat-exchange medium flows, and a plurality of beads
25
which connect tube surfaces
23
,
24
, both mutually opposing within the main tube unit
22
, and cause turbulence in the flow of a heat-exchange medium within the main tube unit
22
.
The bead
25
has an oval and cylindrical shape, whose major axis extends in the longitudinal direction X of the main tube unit
22
. A land
26
and a flow gap
27
are formed between the adjacent beads
25
. The land
26
protrudes from the tube surface
23
and extends to the inside of the main tube unit
22
together with the bead
25
, thereby cross-linking the beads
25
. The heat-exchange medium flows over the lands
26
through the flow gaps
27
.
An unillustrated inlet port which permits inflow of a heat-exchange medium into the main tube unit
22
is formed in one end of the main tube unit
22
in its longitudinal direction X. Further, an outlet port which permits outflow of the heat-exchange medium to the outside of the main tube unit
22
is formed in the other end of the main tube unit
22
in its longitudinal direction X.
The flat tube
21
is formed by folding the opposite sides of a single rectangular plate P, which are located in the widthwise direction thereof, and brazing the edges of the thus-folded sides of the plate P at the center thereof.
A plurality of protuberances T which will be formed into the beads
25
are formed, beforehand and by means of dimpling, at predetermined positions in the surface of the plate P where the tube surfaces
23
and
24
will be formed after processing. The top surfaces of the protuberances T is brazed to the tube surface
24
when the plate P is folded, thus constituting the beads
25
. Further, a plurality of lands
26
are formed, beforehand and by means of dimpling, between the adjacent beads
25
in the surface of the plate P where the tube surfaces
23
and
24
will be formed after processing.
As shown in
FIG. 8
, in the flat tube
21
there are formed a plurality of equally-spaced rows of beads
25
in the longitudinal direction X of the main tube unit
22
. The beads
25
of the adjacent rows are arranged in a staggered configuration.
All the beads
25
are linked by the respective lands
26
such that a bead
25
of the certain row is linked to the beads
25
of adjacent rows located in upstream positions with respect to the direction of flow of the heat-exchange medium as well as to the beads
25
of the adjacent rows located in downstream positions with respect to the direction of flow of the heat-exchange medium.
In the flat tube
21
, the beads
25
are linked by the lands
26
so as to diagonally intersect with respect to the longitudinal direction X of the main tube unit
22
. In
FIG. 8
, reference symbol H designates the distance between the tube surfaces
23
and
24
, and reference symbol “h” designates the height of the land
26
protruding from the tube surface
23
.
FIG
10
Is a perspective view showing the principal section of the flat heat-exchange tube shown in FIG.
8
. As shown in
FIG. 10
, in the flat tube
21
, the heat-exchange medium flows over the lands
26
while the laminar flow of the heat-exchange medium is made turbulent by the plurality of beads
25
.
The heat-exchange medium flowing over the lands
26
flows down from their tops toward the tube surface
23
, thus causing turbulence in the thermal boundary layer of the heat-exchange medium developing in the vicinity of the tube surface
23
. Therefore, the heat-exchange tube of the present invention can make the thermal boundary layer of the heat-exchange medium thinner than does the known flat heat-exchange tube which has only the plurality of beads D and is shown in
FIG. 18
, thus enabling a further improvement in the heat exchange efficiency.
Since in the flat tube
1
all the beads
25
are cross-linked by the lands
26
, the heat-exchange medium flowing between the beads
25
can fall down from the tops of the lands
26
toward the tube surface
23
unfailingly. Accordingly, the thermal boundary layer of the heat-exchange medium developing in the vicinity of the tube surface
23
can be made turbulent unfailingly.
In the flat tube
21
, the beads
25
are linked so as to intersect diagonally by the lands
26
with respect to the longitudinal direction X of the main tube unit
22
A plurality of substantially-rhomboid regions R, each having four sides which are diagonal with respect to the longitudinal direction X of the main tube unit
22
, are formed in the tube surface
23
. In each of the rhomboid regions R, the thermally boundary layer can be made turbulent. Accordingly, the heat-exchange tube of the present invention can unfailingly improve a heat exchange efficiency than does the known heat-exchange tube shown in FIG.
18
.
In the flat tube
21
, the beads
25
are arranged at uniform intervals in the longitudinal direction X of the main tube unit
22
. The beads
25
of the adjacent rows are arranged in a staggered configuration, thus increasing the distribution density of the beads
25
, enabling an increase heat exchange efficiency and an improvement in the compressive strength of the main tube unit
22
.
As shown in
FIG. 10
, the land
26
formed in the flat tube
21
has a circular-arc cross section, thus enabling a decrease in the flow resistance which the heat-exchange medium encounters when flowing over the top of the land
26
. Further, the bead
25
has an oval and cylindrical shape whose major axis extends in the longitudinal direction X of the main tube unit
22
, thereby diminishing the flow resistance which the heat-exchange medium encounters when flowing along the outer circumferential surface of the bead
25
. Accordingly, the heat-exchange tube of the present invention can diminish flow resistance.
The height “h” of the land
26
shown in
FIG. 9
preferably assumes a value of 10 to 60% of the distance H between the tube surfaces
23
and
24
. If the height “h” of the land
26
is under 10% of the distance H between the tube surfaces
23
and
24
, the effect of causing turbulence in the thermal boundary layer of the heat-exchange medium, which would be caused when the heat-exchange medium flows from the top of the land
6
down toward the tube surface
23
, becomes substantially lost. In contrast, if the height “h” of the land
26
exceeds 60% of the distance H between the tube surfaces
23
and
24
, the flow resistance becomes excessively great.
FIG. 11
is a plan view showing a fourth embodiment embodying the inventions described in the appended claims.
FIG. 12
is a perspective view showing the principal section of a heat-exchange tube shown in FIG.
11
. In the following description about the fourth embodiment, those constituent elements which are the same as those described in the third embodiment are assigned the same reference numerals, and repetition of their explanations is omitted.
As shown in
FIGS. 11 and 12
, in a flat tube
210
, the beads
25
are connected by the land
26
such that one bead
25
of a certain row is connected to a bead
25
of the right-side adjacent row located in an upstream position relative to the one bead
25
when viewed in the flowing direction of the heat-exchange medium.
Further, the beads
25
are connected by the land
26
such that one bead
25
of a certain row is connected to a bead
25
of the left-side adjacent row located in a downstream position relative to the one bead
25
when viewed in the flowing direction of the heat-exchange medium.
In the flat tube
210
, there can be formed alternately land regions L—in which the beads
25
are linked by the lands
26
so as to extend diagonally with respect to the longitudinal direction X of the main tube unit
22
—and flow regions M which extend along the land regions L and do not have any lands
26
. Consequently, the heat-exchange medium flows through the main tube unit
22
while flowing over the lands
26
in the land regions L as well as through the flow regions M not having the lands
26
.
The heat-exchange medium that has flowed over the lands
26
can cause turbulence in the thermal boundary layer of the heat-exchange medium developing in the vicinity of the tube surface
23
. Further, the heat-exchange medium can smoothly flow through the flow regions M, because the flow regions M do not have any lands
26
, which would otherwise hinder smooth flow of the heat-exchange medium. Thus, the flat tube
210
of the present embodiment can achieve both an improvement in the heat exchange efficiency and a reduction in the flow resistance.
FIG. 13
is a plan view showing a fifth embodiment. As shown in
FIG. 13
, reinforcement protuberances
221
are formed along the opposite edges of a flat tube
220
, which are located in the widthwise direction thereof, so as to protrude from the tube surface
23
and to be attached to the tube surface
24
. The reinforcement protuberances
221
extend in the longitudinal direction X of the main tube unit
22
.
In the flat tube
220
, the reinforcement protuberances
221
can reinforce U-shaped bends
222
formed along the opposite edges of the main tube unit
22
, the opposite edges being provided in the widthwise direction of the main tube unit
22
The reinforcement protuberances
221
may be provided in, for example, the center of the main tube unit
22
or in the flat tube
21
of the third embodiment.
In the flat tubes
21
,
210
, and
220
, which have been described above, the bead
25
has an oval and cylindrical shape. The shape of the bead
25
is not limited to an oval and cylindrical shape. The bead
25
may assumes any one of the shapes comprising a circular and cylindrical shape, a prismatic shape, a two-step shape, a multi-step shape, and an elongated shape extending in the longitudinal direction X of the main tube unit
22
. Alternatively, the beads
25
of any shapes may be used in combination. Here, the bead
25
desirably assumes a cylindrical shape, because the cylindrical shape diminishes the resistance which the heat-exchange medium encounters during flow.
The lands
26
formed on the surface of the respective flat tubes
21
,
210
, and
220
assume a circular-arc cross section. However, the cross-section of the land
26
is not limited to a circular-arc shape. For example, the land
26
may assume a dihedral shape or a polyhedral shape. However, since a circular-arc cross section diminishes the flow resistance, the land
6
desirably assumes a circular-arc cross section.
In the flat tubes
21
,
210
, and
220
, the beads
25
and the lands
6
are formed so as to protrude from the tube surface
23
. However, the beads
25
and the lands
26
may be formed so as to protrude from both the tube surfaces
23
and
24
or from the tube surface
24
. Alternatively, the beads
5
may be, fixedly sandwiched between the tube surfaces
23
and
24
, and the lands
26
may be fixed on either the tube surface
23
or
24
.
In the flat tubes
21
,
210
, and
220
, the lands
26
cross-link the adjacent beads
25
. However, according to a sixth embodiment as shown in
FIG. 14
, the lands
26
may be formed between the adjacent beads
25
without cross-linking them. The beads
25
to be cross-linked by the lands
26
or the beads
25
having the lands
6
formed therebetween may not necessarily be adjacent to each other. In terms of an improvement in heat exchange efficiency, the beads
25
are desirably adjacent to each other.
Further, each of the flat tubes
21
,
210
, and
220
is formed by folding a single plate P. However, the flat tube may be formed by overlaying one plate on another plate, for example. It goes without saying that the flat tubes
21
,
210
, and
220
may be used for a tube of a known drawn-cup-type heat exchanger or a like heat exchanger. Hereupon, the drawn-cup-type heat exchanger means such a type of heat exchanger in which tanks are integrally formed with tubes.
Further, the present invention can be applied to a flat heat-exchange tube, such as an evaporator, a heater, or a radiator, as well as to a condenser employed in an automotive refrigeration system.
Although the present invention has been described by reference to the above embodiments, the present invention is not limited solely to the embodiments.
Claims
- 1. A flat heat-exchange tube comprising:a plate of which opposite side edges are folded into a flat tube shape and joined together to form a lap joint 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 said plate, tops of said beads being joined to corresponding areas on said flat surface portion, wherein a first side edge of said opposite side edges is located on an Inner side of a second side edge of said opposite side edges, and joined to the top of said bead located opposite said first side edge said lap joint being substantially coextensive with the top of the beads.
- 2. A flat heat-exchange tube according to claim 1, wherein a height of said bead opposing said first side edge is set to be lower than a height of said bead located so as not to oppose said first side edge.
- 3. A flat heat-exchange tube according to claim 2, wherein the height of said bead opposing said first side edge is set to be lower than the height of said bead located so as not to oppose said first side edge by a thickness of said plate.
- 4. A flat heat-exchange tube according to claim 1, wherein said beads are formed in a plurality of rows in a longitudinal direction of said flat surface portion.
- 5. A flat heat-exchange tube according to claim 4, wherein an area where said opposite side edges are joined together is joined to the tops of a plurality of rows of said beads.
- 6. A flat heat-exchange tube according to claim 1, wherein said beads have a substantially cylindrical shaped surface.
- 7. A flat heat-exchange tube according to claim 1, further comprising at least one reinforcement protuberance inwardly protruding from one of said mutually-opposed flat surfaces and in contact with said other mutually-opposed flat surface.
- 8. 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 first and second side edges of the plate into contact with each other to from a lap joint; forming a joint wherein said first side edge contacts with an inner side of said second side edge and is joined with a top of the beads; said lap joint being substantially coextensive with the top of the beads and fixing the joint and a contacted portion of the beads.
- 9. A manufacturing method according to claim 8, wherein the joint is formed so as to be located within one of the two mutually-opposed flat surface portions of the plate.
- 10. A manufacturing method according to claim 8, further comprising 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.
- 11. A method of manufacturing a flat heat-exchange tube according to claim 8, wherein said beads have a substantially cylindrical shaped surface.
- 12. A flat heat-exchange tube comprising:a flat main tube body through which a heat-exchange medium flows, said tube body having opposing inner tube surfaces; a plurality of beads protruding inwardly from at least one of said inner tube surfaces and abutting to said opposite inner tube surface, to thereby cause turbulence in a flow of the heat-exchange medium within said main tube body; and lands positioned between said beads and protruding inwardly from at least one of said inner tube surfaces and spaced from said opposite inner tube surface, to thereby form flow gaps through which the heat-exchange medium flows over said lands.
- 13. A flat heat-exchange tube according to claim 9, wherein said lands cross-link the beads.
- 14. A flat heat-exchange tube according to claim 12, wherein said beads are intermittently arranged in said main tube body with a plurality of rows in a longitudinal direction of said main tube unit, and said beads of a certain row and said beads of another adjacent row are arranged in a staggered configuration, andsaid lands are formed between all said beads of the adjacent rows such that a bead of the certain row is linked to said beads of the adjacent rows located in upstream positions with respect to a flow of the heat-exchange medium as well as to said beads of the adjacent rows located in downstream positions with respect to the flow of the heat-exchange medium.
- 15. A flat heat-exchange tube according to claim 12, wherein said beads are intermittently arranged in said main tube body with a plurality of rows in a longitudinal direction of said main tube unit, and said beads of a certain row and said beads of another adjacent row are arranged in a staggered configuration, andsaid lands are formed between all said beads of adjacent rows such that a bead of a certain row is linked to one of said 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 said beads of the adjacent rows located in downstream positions with respect to the flow of the heat-exchange medium, to thereby linearly link said beads.
- 16. A flat heat-exchange tube according to claim 14, wherein said beads are arranged at uniform intervals in the longitudinal direction of said main tube body, and said beads of a certain row and said beads of another adjacent row are arranged in a staggered configuration.
- 17. A flat heat-exchange tube according to claim 15, wherein said beads are arranged at uniform intervals in the longitudinal direction of said main tube body, and said beads of a certain row and said beads of another adjacent row are arranged in a staggered configuration.
- 18. A flat heat-exchange tube according to claim 12, wherein said lands have a circular-arc cross section.
- 19. A flat heat-exchange tube according to claim 12, wherein said beads have a substantially cylindrical shaped surface.
- 20. A flat heat-exchange tube according to claim 9, further comprising at least one reinforcement protuberance inwardly protruding from one of said inner tube surfaces and in contact with said opposite inner tube surface.
- 21. A flat heat-exchange tube according to claim 9, wherein a height h of said lands is between 10 and 60 percent of a distance H between said inner tube surfaces.
Priority Claims (2)
Number |
Date |
Country |
Kind |
11-011113 |
Jan 1999 |
JP |
|
11-022771 |
Jan 1999 |
JP |
|
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DE |
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EP |
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EP |
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FR |
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SE |