U.S. patent application number 11/610186 was filed with the patent office on 2007-06-14 for heat exchanger and method of manufacturing outside plate used for header tanks of heat exchanger.
This patent application is currently assigned to SHOWA DENKO K.K.. Invention is credited to Shunsuke Igawa, Kazuhiko MINAMI, Hironaka Sasaki.
Application Number | 20070131392 11/610186 |
Document ID | / |
Family ID | 38109052 |
Filed Date | 2007-06-14 |
United States Patent
Application |
20070131392 |
Kind Code |
A1 |
MINAMI; Kazuhiko ; et
al. |
June 14, 2007 |
HEAT EXCHANGER AND METHOD OF MANUFACTURING OUTSIDE PLATE USED FOR
HEADER TANKS OF HEAT EXCHANGER
Abstract
A method of manufacturing an outside plate used for a heat
exchanger header tank configured such that an outside plate having
an outwardly bulging portion, an inside plate, and an intermediate
plate are brazed together in layers. A thick portion is formed on
an outside-plate forming metal plate at a center portion with
respect to the width direction thereof. Subsequently, a press work
is performed on the outside-plate forming metal plate so as to form
the outwardly bulging portion by making use of the thick portion. A
connection portion having a curvature radius of 1 mm or less is
formed between an inner wall surface of the outwardly bulging
portion and each of surfaces of the outside plate located on the
opposite sides of the outwardly bulging portion. This method
enables manufacture of an outside plate which reduces the weight
while securing sufficient withstanding pressure.
Inventors: |
MINAMI; Kazuhiko;
(Oyama-shi, JP) ; Sasaki; Hironaka; (Oyama-shi,
JP) ; Igawa; Shunsuke; (Oyama-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
SHOWA DENKO K.K.
Tokyo
JP
|
Family ID: |
38109052 |
Appl. No.: |
11/610186 |
Filed: |
December 13, 2006 |
Current U.S.
Class: |
165/110 ;
165/176; 165/178 |
Current CPC
Class: |
F28D 1/05391 20130101;
F28D 2021/0071 20130101; F28D 1/0391 20130101; F28F 9/0224
20130101; F28F 1/022 20130101; F28D 2021/0073 20130101; F28F 9/0246
20130101 |
Class at
Publication: |
165/110 ;
165/176; 165/178 |
International
Class: |
F28B 1/00 20060101
F28B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 14, 2005 |
JP |
2005-360387 |
Claims
1. A heat exchanger comprising a pair of header tanks disposed
apart from each other and a plurality of flat heat exchange tubes
disposed in parallel between the two header tanks and having
opposite end portions connected to the respective header tanks,
each of the two header tanks being configured such that an outside
plate, an inside plate, and an intermediate plate intervening
between the outside and inside plates are brazed together in
layers, the outside plate having an outwardly bulging portion
extending in a longitudinal direction thereof and having an opening
closed by the intermediate plate, the inside plate having a
plurality of tube insertion holes in the form of through-holes
formed in a region corresponding to the outwardly bulging portion
of the outside plate and spaced apart from one another along a
longitudinal direction of the inside plate, and the intermediate
plate having a plurality of communication holes in the form of
through-holes formed for allowing the respective tube insertion
holes of the inside plate to communicate with the interior of the
outwardly bulging portion of the outside plate, wherein the outside
plate of each header tank is formed of a metal plate and through a
press work performed thereon, and a connection portion between an
inner wall surface of the outwardly bulging portion of the outside
plate and a surface of the outside plate which surface is joined to
the intermediate plate has a curvature radius of 1 mm or less.
2. A heat exchanger according to claim 1, wherein the connection
portion between the inner wall surface of the outwardly bulging
portion and the surface of the outside plate joined to the
intermediate plate has a curvature radius of 0.5 mm or less.
3. A heat exchanger according to claim 1, wherein the outside plate
has a thickness of 2 mm or greater.
4. A method of manufacturing an outside plate used for a heat
exchanger header tank which is configured such that an outside
plate, an inside plate, and an intermediate plate intervening
between the outside and inside plates are brazed together in
layers, the outside plate having an outwardly bulging portion
extending in a longitudinal direction thereof and having an opening
closed by the intermediate plate, the inside plate having a
plurality of tube insertion holes in the form of through-holes
formed in a region corresponding to the outwardly bulging portion
of the outside plate and spaced apart from one another along a
longitudinal direction of the inside plate, and the intermediate
plate having a plurality of communication holes in the form of
through-holes formed for allowing the respective tube insertion
holes of the inside plate to communicate with the interior of the
outwardly bulging portion of the outside plate, the method
comprising the steps of: forming a thick portion on an
outside-plate forming metal plate at a center portion with respect
to the width direction thereof, the thick portion being thicker
than the remaining thin portion; and performing a press work on the
outside-plate forming metal plate so as to form the outwardly
bulging portion by making use of the thick portion such that a
connection portion having a curvature radius of 1 mm or less is
formed between an inner wall surface of the outwardly bulging
portion and each of surfaces of the outside plate located on the
opposite sides of the outwardly bulging portion and being
continuous with the inner wall surface.
5. A method of manufacturing an outside plate used for a heat
exchanger header tank according to claim 4, wherein the thick
portion is formed by performing a press work on the outside-plate
forming metal plate.
6. A method of manufacturing an outside plate used for a heat
exchanger header tank according to claim 5, wherein the thick
portion of the outside-plate forming metal plate has a thickness
1.05 to 1.5 times that of the remaining thin portion.
7. A method of manufacturing an outside plate used for a heat
exchanger header tank according to claim 4, wherein a connection
portion having a curvature radius of 0.5 mm or less is formed
between the inner wall surface of the outwardly bulging portion and
each of the surfaces of the outside plate located on the opposite
sides of the outwardly bulging portion and being continuous with
the inner wall surface.
8. A method of manufacturing an outside plate used for a heat
exchanger header tank according to claim 4, wherein the outside
plate has a thickness of 2 mm or greater in its final shape.
9. A method of manufacturing an outside plate used for a heat
exchanger header tank which is configured such that an outside
plate, an inside plate, and an intermediate plate intervening
between the outside and inside plates are brazed together in
layers, the outside plate having an outwardly bulging portion
extending in a longitudinal direction thereof and having an opening
closed by the intermediate plate, the inside plate having a
plurality of tube insertion holes in the form of through-holes
formed in a region corresponding to the outwardly bulging portion
of the outside plate and spaced apart from one another along a
longitudinal direction of the inside plate, and the intermediate
plate having a plurality of communication holes in the form of
through-holes formed for allowing the respective tube insertion
holes of the inside plate to communicate with the interior of the
outwardly bulging portion of the outside plate, the method
comprising the steps of: performing a first press work on an
outside-plate forming metal plate so as to form a preliminary
bulging portion having a bulging height greater than that of the
outwardly bulging portion; and performing a second press work on
the outside-plate forming metal plate having the preliminary
bulging portion, while restraining the outside-plate forming metal
plate from the opposite sides with respect to the width direction
thereof, so as to form the outwardly bulging portion from the
preliminary bulging portion such that a connection portion having a
curvature radius of 1 mm or less is formed between an inner wall
surface of the outwardly bulging portion and each of surfaces of
the outside plate located on the opposite sides of the outwardly
bulging portion and being continuous with the inner wall
surface.
10. A method of manufacturing an outside plate used for a heat
exchanger header tank according to claim 9, wherein the step of
performing the second press work includes cutting opposite side
edge portions of the outside-plate forming metal plate by use of
one of dies used for the press work before formation of the
outwardly bulging portion from the preliminary bulging portion, and
restraining the outside-plate forming metal plate having the
preliminary bulging portion from the opposite sides with respect to
the width direction thereof by use of the die.
11. A method of manufacturing an outside plate used for a heat
exchanger header tank according to claim 9, wherein a connection
portion having a curvature radius of 0.5 mm or less is formed
between the inner wall surface of the outwardly bulging portion and
each of the surfaces of the outside plate located on the opposite
sides of the outwardly bulging portion and being continuous with
the inner wall surface.
12. A method of manufacturing an outside plate used for a heat
exchanger header tank according to claim 9, wherein the outside
plate has a thickness of 2 mm or greater in its final shape.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a heat exchanger and a
method of manufacturing an outside plate used for header tanks of a
heat exchanger. More particularly, the present invention relates to
a heat exchanger that can be favorably used as a gas cooler or an
evaporator of a supercritical refrigeration cycle in which a
CO.sub.2 (carbon dioxide) refrigerant or a like supercritical
refrigerant is used, and to a method of manufacturing an outside
plate used for header tanks of such a heat exchanger.
[0002] Herein and in the appended claims, the term "supercritical
refrigeration cycle" means a refrigeration cycle in which a
refrigerant on the high-pressure side is in a supercritical state;
i.e., assumes a pressure in excess of a critical pressure. The term
"supercritical refrigerant" means a refrigerant used in a
supercritical refrigeration cycle. Also, herein and in the appended
claims, the downstream side of flow (represented by arrow X in FIG.
1) of air through air-passing clearances between adjacent heat
exchange tubes will be referred to as the "front," and the opposite
side as the "rear."
[0003] A conventionally known heat exchanger for use in a
supercritical refrigeration cycle includes a pair of header tanks
disposed apart from each other; flat heat exchange tubes disposed
in parallel at intervals between the two header tanks and having
opposite end portions connected to the respective header tanks; and
fins disposed in respective air-passing clearances between the
adjacent heat exchange tubes and brazed to the heat exchange tubes
(refer to Japanese Patent Application Laid-Open (kokai) No.
2005-300135). Each of the two header tanks is configured such that
an outside plate, an inside plate, and an intermediate plate
intervening between the outer and inside plates are brazed together
in layers. The outside plate has an outwardly bulging portion
extending in the longitudinal direction thereof and having an
opening closed by the intermediate plate. The inside plate has a
plurality of tube insertion holes in the form of through-holes
formed in a region corresponding to the outwardly bulging portion
of the outside plate and spaced apart from one another along the
longitudinal direction thereof. The intermediate plate has a
plurality of communication holes slightly larger than the tube
insertion holes of the inside plate and in the form of
through-holes formed for allowing the respective tube insertion
holes to communicate with the interior of the outwardly bulging
portion of the outside plate. Opposite end portions of the heat
exchange tubes are inserted through the respective tube insertion
holes of the inside plates and into the respective communication
holes of the intermediate plates of the two header tanks. The
entire outer peripheral surfaces of opposite end portions of the
heat exchange tubes are brazed to the respective entire peripheral
wall surfaces of the tube insertion holes of the inside plates of
the two header tanks. At least one outwardly bulging portion of
each header tank serves as a refrigerant-flow outwardly bulging
portion in which refrigerant flows in the longitudinal direction
thereof. In each header tank, the communication holes of the
intermediate plate communicating with the refrigerant-flow
outwardly bulging portion are connected together by means of
communication portions formed in the intermediate plate.
[0004] In the heat exchanger described in the publication, in order
to increase the withstanding pressure of each header tank, the
outside plate is formed of an aluminum plate having a relatively
large thickness and through a press work performed thereon.
However, in this case, the weight of the heat exchanger
increases.
SUMMARY OF THE INVENTION
[0005] An object of the present invention is to solve the above
problem and to provide a heat exchanger which has a reduced weight
and whose header tanks have a sufficient withstanding pressure, and
a method of manufacturing an outside plate used for header tanks of
a heat exchanger.
[0006] To fulfill the above object, the present invention comprises
the following modes.
[0007] 1) A heat exchanger comprising a pair of header tanks
disposed apart from each other and a plurality of flat heat
exchange tubes disposed in parallel between the two header tanks
and having opposite end portions connected to the respective header
tanks, each of the two header tanks being configured such that an
outside plate, an inside plate, and an intermediate plate
intervening between the outside and inside plates are brazed
together in layers, the outside plate having an outwardly bulging
portion extending in a longitudinal direction thereof and having an
opening closed by the intermediate plate, the inside plate having a
plurality of tube insertion holes in the form of through-holes
formed in a region corresponding to the outwardly bulging portion
of the outside plate and spaced apart from one another along a
longitudinal direction of the inside plate, and the intermediate
plate having a plurality of communication holes in the form of
through-holes formed for allowing the respective tube insertion
holes of the inside plate to communicate with the interior of the
outwardly bulging portion of the outside plate,
[0008] wherein the outside plate of each header tank is formed of a
metal plate and through a press work performed thereon, and a
connection portion between an inner wall surface of the outwardly
bulging portion of the outside plate and a surface of the outside
plate which surface is joined to the intermediate plate has a
curvature radius of 1 mm or less.
[0009] 2) A heat exchanger according to par. 1), wherein the
connection portion between the inner wall surface of the outwardly
bulging portion and the surface of the outside plate joined to the
intermediate plate has a curvature radius of 0.5 mm or less.
[0010] 3) A heat exchanger according to par. 1), wherein the
outside plate has a thickness of 2 mm or greater.
[0011] 4) A method of manufacturing an outside plate used for a
heat exchanger header tank which is configured such that an outside
plate, an inside plate, and an intermediate plate intervening
between the outside and inside plates are brazed together in
layers, the outside plate having an outwardly bulging portion
extending in a longitudinal direction thereof and having an opening
closed by the intermediate plate, the inside plate having a
plurality of tube insertion holes in the form of through-holes
formed in a region corresponding to the outwardly bulging portion
of the outside plate and spaced apart from one another along a
longitudinal direction of the inside plate, and the intermediate
plate having a plurality of communication holes in the form of
through-holes formed for allowing the respective tube insertion
holes of the inside plate to communicate with the interior of the
outwardly bulging portion of the outside plate, the method
comprising the steps of:
[0012] forming a thick portion on an outside-plate forming metal
plate at a center portion with respect to the width direction
thereof, the thick portion being thicker than the remaining thin
portion; and
[0013] performing a press work on the outside-plate forming metal
plate so as to form the outwardly bulging portion by making use of
the thick portion such that a connection portion having a curvature
radius of 1 mm or less is formed between an inner wall surface of
the outwardly bulging portion and each of surfaces of the outside
plate located on the opposite sides of the outwardly bulging
portion and being continuous with the inner wall surface.
[0014] 5) A method of manufacturing an outside plate used for a
heat exchanger header tank according to par. 4), wherein the thick
portion is formed by performing a press work on the outside-plate
forming metal plate.
[0015] 6) A method of manufacturing an outside plate used for a
heat exchanger header tank according to par. 5), wherein the thick
portion of the outside-plate forming metal plate has a thickness
1.05 to 1.5 times that of the remaining thin portion.
[0016] 7) A method of manufacturing an outside plate used for a
heat exchanger header tank according to par. 4), wherein a
connection portion having a curvature radius of 0.5 mm or less is
formed between the inner wall surface of the outwardly bulging
portion and each of the surfaces of the outside plate located on
the opposite sides of the outwardly bulging portion and being
continuous with the inner wall surface.
[0017] 8) A method of manufacturing an outside plate used for a
heat exchanger header tank according to par. 4), wherein the
outside plate has a thickness of 2 mm or greater in its final
shape.
[0018] 9) A method of manufacturing an outside plate used for a
heat exchanger header tank which is configured such that an outside
plate, an inside plate, and an intermediate plate intervening
between the outside and inside plates are brazed together in
layers, the outside plate having an outwardly bulging portion
extending in a longitudinal direction thereof and having an opening
closed by the intermediate plate, the inside plate having a
plurality of tube insertion holes in the form of through-holes
formed in a region corresponding to the outwardly bulging portion
of the outside plate and spaced apart from one another along a
longitudinal direction of the inside plate, and the intermediate
plate having a plurality of communication holes in the form of
through-holes formed for allowing the respective tube insertion
holes of the inside plate to communicate with the interior of the
outwardly bulging portion of the outside plate, the method
comprising the steps of:
[0019] performing a first press work on an outside-plate forming
metal plate so as to form a preliminary bulging portion having a
bulging height greater than that of the outwardly bulging portion;
and
[0020] performing a second press work on the outside-plate forming
metal plate having the preliminary bulging portion, while
restraining the outside-plate forming metal plate from the opposite
sides with respect to the width direction thereof, so as to form
the outwardly bulging portion from the preliminary bulging portion
such that a connection portion having a curvature radius of 1 mm or
less is formed between an inner wall surface of the outwardly
bulging portion and each of surfaces of the outside plate located
on the opposite sides of the outwardly bulging portion and being
continuous with the inner wall surface.
[0021] 10) A method of manufacturing an outside plate used for a
heat exchanger header tank according to par. 9), wherein the step
of performing the second press work includes cutting opposite side
edge portions of the outside-plate forming metal plate by use of
one of dies used for the press work before formation of the
outwardly bulging portion from the preliminary bulging portion, and
restraining the outside-plate forming metal plate having the
preliminary bulging portion from the opposite sides with respect to
the width direction thereof by use of the die.
[0022] 11) A method of manufacturing an outside plate used for a
heat exchanger header tank according to par. 9), wherein a
connection portion having a curvature radius of 0.5 mm or less is
formed between the inner wall surface of the outwardly bulging
portion and each of the surfaces of the outside plate located on
the opposite sides of the outwardly bulging portion and being
continuous with the inner wall surface.
[0023] 12) A method of manufacturing an outside plate used for a
heat exchanger header tank according to par. 9), wherein the
outside plate has a thickness of 2 mm or greater in its final
shape.
[0024] According to the heat exchanger of par. 1), the outside
plate of each header tank is formed of a metal plate and through a
press work performed thereon, and a connection portion between an
inner wall surface of the outwardly bulging portion and a surface
of the outside plate which surface is joined to the intermediate
plate has a curvature radius of 1 mm or less. Therefore, the stress
concentration at the connection portion between the inner wall
surface of the outwardly bulging portion and the surface of the
outside plate joined to the intermediate plate is mitigated, and
thus, the withstanding pressure of the header tank increases. In
addition, since the withstanding pressure is increased through
mitigation of the stress concentration at the connection portion
between the inner wall surface of the outwardly bulging portion and
the surface of the outside plate joined to the intermediate plate,
the thickness of the outside plate can be reduced as compared with
the heat exchanger disclosed in the above-described publication.
Accordingly, the weight of the header tanks, and thus, the weight
of the entire heat exchanger using the header tanks can be
reduced.
[0025] According to the heat exchanger of par. 2), the connection
portion between the inner wall surface of the outwardly bulging
portion and the surface of the outside plate joined to the
intermediate plate has a curvature radius of 0.5 mm or less.
Therefore, the stress concentration at the connection portion
between the inner wall surface of the outwardly bulging portion and
the surface of the outside plate joined to the intermediate plate
is mitigated more effectively, and thus, the withstanding pressure
of the header tanks increases more.
[0026] According to the heat exchanger of par. 3), since the
outside plate has a thickness of 2 mm or greater, the withstanding
pressure of the header tanks increases.
[0027] According to the method of manufacturing an outside plate of
par. 4), a thick portion is formed on an outside-plate forming
metal plate at a center portion with respect to the width direction
thereof, the thick portion being thicker than the remaining thin
portion, and a press work is then performed on the outside-plate
forming metal plate so as to form the outwardly bulging portion by
making use of the thick portion. Therefore, the material of the
thick portion flows throughout press working dies, whereby a
connection portion having a curvature radius of 1 mm or less can be
formed between the inner wall surface of the outwardly bulging
portion and each of the surfaces of the outside plate located on
the opposite sides of the outwardly bulging portion and being
continuous with the inner wall surface. Accordingly, a heat
exchanger header tank using the outside plate manufactured by this
method has an increased withstanding pressure. As a result, the
thickness of the outside plate can be reduced as compared with the
heat exchanger disclosed in the above-described publication, and
the weight of the header tanks, and thus, the weight of the entire
heat exchanger using the header tanks can be reduced.
[0028] In addition, the method of par. 4) enables use of a
high-strength aluminum material on which extrusion cannot be
performed. This also increases the withstanding pressure of the
heat exchanger header tank using the manufactured outside
plate.
[0029] According to the method of manufacturing an outside plate of
par. 5), the thick portion can be formed on the outside-plate
forming metal plate relatively easily.
[0030] According to the method of manufacturing an outside plate of
par. 6), the thick portion of the outside-plate forming metal plate
has a thickness 1.05 to 1.5 times that of the remaining thin
portion. Therefore, flow of the material of the thick portion
throughout the press working dies occurs without fail, so that the
outside-plate forming metal plate can be formed into a target
shape, and thus, a connection portion having a curvature radius of
1 mm or less can be formed between the inner wall surface of the
outwardly bulging portion and each of the surfaces of the outside
plate located on the opposite sides of the outwardly bulging
portion and being continuous with the inner wall surface.
[0031] According to the method of manufacturing an outside plate of
par. 7), a connection portion having a curvature radius of 0.5 mm
or less is formed between the inner wall surface of the outwardly
bulging portion and each of the surfaces of the outside plate
located on the opposite sides of the outwardly bulging portion and
being continuous with the inner wall surface. In a heat exchanger
header tank using the outside plate manufactured by this method,
the stress concentration at the connection portion between the
inner wall surface of the outwardly bulging portion and the surface
of the outside plate joined to the intermediate plate can be
mitigated more effectively, and thus, the withstanding pressure of
the header tank increases more.
[0032] In the case where the outside plate to be manufactured has a
thickness of 2 mm or greater in its final shape as in the method of
manufacturing an outside plate of par. 8), forming into the target
shape through a press work is difficult, and when a press work is
performed on an outside-plate forming plate without formation of
the above-described thick portion, a connection portion having a
large curvature radius of, for example, 3 mm or greater may be
formed between the inner wall surface of the outwardly bulging
portion and each of the surfaces of the outside plate located on
the opposite sides of the outwardly bulging portion and being
continuous with the inner wall surface. In a heat exchanger header
tank using such an outside plate, stress concentrates at the brazed
portions between the intermediate plate and portions of the outside
plate located on the front and rear sides of the outwardly bulging
portion, whereby the withstanding pressure of the heat exchanger
header tank may decrease.
[0033] However, even in such a case, according to the method of
par. 4), the curvature radius of the connection portion between the
inner wall surface of the outwardly bulging portion and each of the
surfaces of the outside plate located on the opposite sides of the
outwardly bulging portion and being continuous with the inner wall
surface can be made 1 mm or less. Accordingly, the stress
concentration at the brazed portions between the intermediate plate
and portions of the outside plate located on the front and rear
sides of the outwardly bulging portion can be mitigated.
[0034] According to the method of manufacturing an outside plate of
par. 9), a first press work is performed on an outside-plate
forming metal plate so as to form a preliminary bulging portion
having a bulging height greater than that of the outwardly bulging
portion, and then a second press work is performed on the
outside-plate forming metal plate having the preliminary bulging
portion, while restraining the outside-plate forming metal plate
from the opposite sides with respect to the width direction
thereof. Therefore, the outwardly bulging portion can be formed
from the preliminary bulging portion, and the curvature radius of
the connection portion between the inner wall surface of the
outwardly bulging portion and each of the surfaces of the outside
plate located on the opposite sides of the outwardly bulging
portion and being continuous with the inner wall surface can be
made 1 mm or less. Accordingly, a heat exchanger header tank using
the outside plate manufactured by this method has an increased
withstanding pressure. As a result, the thickness of the outside
plate can be reduced as compared with the heat exchanger disclosed
in the above-described publication, and the weight of the header
tanks, and thus, the weight of the entire heat exchanger using the
header tanks can be reduced.
[0035] In addition, the method of par. 9) enables use of a
high-strength aluminum material on which extrusion cannot be
performed. This also increases the withstanding pressure of the
header tank using the manufactured outside plate.
[0036] According to the method of manufacturing an outside plate of
par. 10), when the second press work is performed, opposite side
edge portions of the outside-plate forming metal plate are cut by
use of one of dies used for the press work before formation of the
outwardly bulging portion from the preliminary bulging portion, and
the outside-plate forming metal plate having the preliminary
bulging portion is restrained from the opposite sides with respect
to the width direction thereof by use of the die. Therefore, the
outside-plate forming metal plate can be restrained from the
opposite sides without fail.
[0037] According to the method of manufacturing an outside plate of
par. 11), a connection portion having a curvature radius of 0.5 mm
or less is formed between the inner wall surface of the outwardly
bulging portion and each of the surfaces of the outside plate
located on the opposite sides of the outwardly bulging portion and
being continuous with the inner wall surface. In a heat exchanger
header tank using the outside plate manufactured by this method,
the stress concentration at the connection portion between the
inner wall surface of the outwardly bulging portion and the surface
of the outside plate joined to the intermediate plate can be
mitigated more effectively, and thus, the withstanding pressure of
the header tank increases more.
[0038] In the case where the outside plate to be manufactured has a
thickness of 2 mm or greater in its final shape as in the method of
manufacturing an outside plate of par. 12), forming into the target
shape through a press work is difficult, and when a press work is
performed on an outside-plate forming plate without formation of
the above-described preliminary bulging portion, a connection
portion having a large curvature radius of, for example, 3 mm or
greater may be formed between the inner wall surface of the
outwardly bulging portion and each of the surfaces of the outside
plate located on the opposite sides of the outwardly bulging
portion and being continuous with the inner wall surface. In a heat
exchanger header tank using such an outside plate, stress
concentrates at the brazed portions between the intermediate plate
and portions of the outside plate located on the front and rear
sides of the outwardly bulging portion, whereby the withstanding
pressure of the heat exchanger header tank may decrease.
[0039] However, even in such a case, according to the method of
par. 9), the curvature radius of the connection portion between the
inner wall surface of the outwardly bulging portion and each of the
surfaces of the outside plate located on the opposite sides of the
outwardly bulging portion and being continuous with the inner wall
surface can be made 1 mm or less. Accordingly, the stress
concentration at the brazed portions between the intermediate plate
and portions of the outside plate located on the front and rear
sides of the outwardly bulging portion can be mitigated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] FIG. 1 is a perspective view showing the overall
construction of a gas cooler to which the heat exchanger according
to the present invention is applied;
[0041] FIG. 2 is a fragmentary view in vertical section showing the
gas cooler of FIG. 1 as it is seen frontward from rear;
[0042] FIG. 3 is an exploded perspective view showing a first
header tank of the gas cooler of FIG. 1;
[0043] FIG. 4 is an enlarged view in section taken along line A-A
of FIG. 2;
[0044] FIG. 5 is an enlarged view in section taken along line B-B
of FIG. 2;
[0045] FIG. 6 is an enlarged view in section taken along line C-C
of FIG. 2;
[0046] FIG. 7 is a set of views showing a method of manufacturing
the outside plate of the first header tank of the gas cooler of
FIG. 1;
[0047] FIG. 8 is an exploded perspective view showing a method of
manufacturing the first header tank of the gas cooler of FIG.
1;
[0048] FIG. 9 is an exploded perspective view showing a method of
manufacturing a second header tank of the gas cooler of FIG. 1;
[0049] FIG. 10 is a cross-sectional view showing a heat exchange
tube of the gas cooler of FIG. 1;
[0050] FIG. 11 is a fragmentary enlarged view of FIG. 10;
[0051] FIG. 12 is a set of views showing a method of manufacturing
the heat exchange tube shown in FIG. 10; and
[0052] FIG. 13 is a set of views showing another method of
manufacturing the outside plate of the first header tank of the gas
cooler of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0053] Embodiments of the present invention will next be described
in detail with reference to the drawings. These embodiments are
implemented by applying a heat exchanger according to the present
invention to a gas cooler of a supercritical refrigeration
cycle.
[0054] In the following description, the upper, lower, left-hand,
and right-hand sides of FIGS. 1 and 2 will be referred to as
"upper," "lower," "left," and "right," respectively. Further, in
the following description, the term "aluminum" encompasses aluminum
alloys in addition to pure aluminum.
[0055] FIGS. 1 and 2 show the overall construction of a gas cooler
to which the heat exchanger according to the present invention is
applied. FIGS. 3 to 6 show the configuration of essential portions
of the gas cooler of FIG. 1. FIGS. 7 to 9 show a method of
manufacturing header tanks. FIGS. 10 and 11 show a heat exchange
tube. FIG. 12 shows a method of manufacturing the heat exchange
tube.
[0056] With reference to FIG. 1, a gas cooler 1 of a supercritical
refrigeration cycle wherein a supercritical refrigerant, such as
CO.sub.2, is used includes two header tanks 2 and 3 extending
vertically and spaced apart from each other in the left-right
direction; a plurality of flat heat exchange tubes 4 arranged in
parallel between the two header tanks 2 and 3 and spaced apart from
one another in the vertical direction; corrugated fins 5 arranged
in respective air-passing clearances between adjacent heat exchange
tubes 4 and at the outside of the upper-end and lower-end heat
exchange tubes 4 and each brazed to the adjacent heat exchange
tubes 4 or to the upper-end or lower-end heat exchange tube 4; and
side plates 6 of aluminum arranged externally of and brazed to the
respective upper-end and lower-end corrugated fins 5. In the case
of this embodiment, the header tank 2 at the right will be referred
to as the "first header tank," and the header tank 3 at the left as
the "second header tank."
[0057] As shown in FIGS. 2 to 6, the first header tank 2 is
configured such that an outside plate 7, an inside plate 8, and an
intermediate plate 9 intervening between the outside plate 7 and
the inside plate 8 are brazed together in layers. The outside plate
7 and the inside plate 8 are each formed from a brazing sheet
having a brazing material layer on each of opposite sides; herein,
an aluminum brazing sheet. The intermediate plate 9 is formed from
a bare metal material; herein, a bare aluminum material.
[0058] The outside plate 7 has a plurality of; herein, two,
dome-like outwardly bulging portions 11A and 11B spaced apart from
each other in the vertical direction. The outwardly bulging
portions 11A and 11B extend vertically, and have the same bulging
height, length, and width. In the outside plate 7, a peripheral
portion around a leftward-facing opening of each of the outwardly
bulging portions 11A and 11B is brazed to the intermediate plate 9,
whereby the intermediate plate 9 covers the leftward-facing
openings of the outwardly bulging portions 11A and 11B. As a
result, the interior of each of the outwardly bulging portions 11A
and 11B serves as a refrigerant flow section whose upper and lower
ends are closed. Those portions of the first header tank 2 which
correspond to the outwardly bulging portions 11A and 11B serve as
respective header sections. The curvature radius R of a connection
portion 26 between the inner wall surface of each outwardly bulging
portion 11A, 11B and each of inside surfaces of the outside plate 7
which are located on the front and rear sides of the outwardly
bulging portion 11A, 11B and which extend in the left-right
direction is not greater than 1 mm, preferably, not greater than
0.5 mm (see FIG. 4 and FIG. 6). The outside plate 7 has a thickness
of 2 mm or greater.
[0059] A refrigerant inlet 12 is formed in a crest portion of the
upper outwardly bulging portion 11A of the outside plate 7. An
inlet member 13 of a metal; herein, a bare aluminum material,
having a refrigerant inflow channel 14 in communication with the
refrigerant inlet 12 is brazed to the outer surface of the
outwardly bulging portion 11A by use of the brazing material on the
outer surface of the outside plate 7. A refrigerant outlet 15 is
formed in a crest portion of the lower outwardly bulging portion
11B. An outlet member 16 of a metal; herein, a bare aluminum
material, having a refrigerant outflow channel 17 in communication
with the refrigerant outlet 15 is brazed to the outer surface of
the outwardly bulging portion 11B by use of the brazing material on
the outer surface of the outside plate 7. The outside plate 7 is
formed, by press work, from an aluminum brazing sheet having a
brazing material layer on each of opposite sides.
[0060] A plurality of tube insertion holes 18 elongated in the
front-rear direction are formed through the inside plate 8 and are
vertically spaced apart from one another. An upper-half group of
tube insertion holes 18 are formed within a vertical range
corresponding to the upper outwardly bulging portion 11A of the
outside plate 7. Similarly, a lower-half group of tube insertion
holes 18 are formed within a vertical range corresponding to the
lower outwardly bulging portion 11B. The tube insertion holes 18
have a front-to-rear length slightly longer than the front-to-rear
width of the outwardly bulging portions 11A and 11B such that front
and rear end portions of the tube insertion holes 18 project
outward beyond the front and rear ends, respectively, of the
outwardly bulging portions 11A and 11B. Front and rear edge
portions of the inside plate 8 have integrally formed respective
cover walls 19. The cover walls 19 project rightward such that
their ends reach the outer surface of the outside plate 7, and
cover respective boundary portions between the outside plate 7 and
the intermediate plate 9 along the overall length of the boundary
portions. The cover walls 19 are brazed to the front and rear side
surfaces, respectively, of the outside plate 7 and the intermediate
plate 9. The projecting end of each of the cover walls 19 has a
plurality of integrally formed engaging portions 21 which are
vertically spaced apart from one another. The engaging portions 21
of the cover walls 19 are engaged with and brazed to the outer
surface of the outside plate 7. The inside plate 8 is formed, by
press work, from an aluminum brazing sheet having a brazing
material layer on each of opposite sides.
[0061] The intermediate plate 9 has communication holes 22 in the
form of through-holes for allowing the tube insertion holes 18 of
the inside plate 8 to communicate with the interiors of the
outwardly bulging portions 11A and 11B and in a number equal to the
number of the tube insertion holes 18. The communication holes 22
positionally coincide with the respective tube insertion holes 18
of the inside plate 8 and have the same width as the tube insertion
holes 18. The intermediate plate 9 has stepped portions 25 formed
on the peripheral wall surface of each communication hole 22 of the
intermediate plate 9 at opposite end portions thereof with respect
to the hole-length direction (front and rear end portions) such
that the stepped portions 25 are located at an intermediate
position with respect to the thickness direction of the
intermediate plate 9. The stepped portions 25 project inward with
respect to the hole-length direction of the communication hole 22.
A corresponding end surface of the corresponding heat exchange tube
4 engages the stepped portions 25. The projecting height of the
stepped portion 25 of the intermediate plate 9 from the peripheral
wall surface of the communication hole 22 is determined so as not
to cover refrigerant channels 4a, which will be described later, of
the heat exchange tube 4. An upper-half group of tube insertion
holes 18 of the inside plate 8 communicate with the interior of the
upper outwardly bulging portion 11A via an upper-half group of
respective communication holes 22 of the intermediate plate 9.
Similarly, a lower-half group of tube insertion holes 18
communicate with the interior of the lower outwardly bulging
portion 11B via a lower-half group of respective communication
holes 22 of the intermediate plate 9. All of the communication
holes 22 in communication with the interior of the upper outwardly
bulging portion 11A communicate with one another via communication
portions 23, and all of the communication holes 22 in communication
with the interior of the lower outwardly bulging portion 11B
communicate with one another via other communication portions 23.
The communication portions 23 are formed by cutting off portions
between the adjacent communication holes 22 in the intermediate
plate 9. Thus, the intermediate plate 9 has a refrigerant flow
section communicating with the refrigerant flow section within the
outwardly bulging portion 11A, and a refrigerant flow section
communicating with the refrigerant flow section within the
outwardly bulging portion 11B.
[0062] The second header tank 3 has substantially the same
construction as the first header tank 2, and like features and
parts are designated by like reference numerals. The two header
tanks 2 and 3 are disposed such that the respective inside plates 8
face each other. The second header tank 3 differs from the first
header tank 2 in that the outside plate 7 has dome-like outwardly
bulging portions provided in a number one fewer than the outwardly
bulging portions 11A and 11B of the first header tank 2; herein, a
single dome-like outwardly bulging portion 24, which extends from
an upper end portion to a lower end portion of the outside plate 7
and is opposed to the outwardly bulging portions 11A and 11B of the
first header tank 2; the outwardly bulging portion 24 does not have
a refrigerant inlet and a refrigerant outlet; all of the tube
insertion holes 18 of the inside plate 8 communicate with the
interior of the outwardly bulging portion 24 via all of the
respective communication holes 22 of the intermediate plate 9; and
all of the communication holes 22 of the intermediate plate 9
communicate with one another via the communication portions 23,
which are formed by cutting off portions between the adjacent
communication holes 22. The outwardly bulging portion 24 has the
same bulging height and width as the outwardly bulging portions 11A
and 11B of the first header tank 2. In the outside plate 7, a
peripheral portion around a rightward-facing opening of the
outwardly bulging portion 24 is brazed to the intermediate plate 9,
whereby the intermediate plate 9 covers the rightward-facing
opening of the outwardly bulging portion 24. As a result, the
interior of the outwardly bulging portion 24 serves as a
refrigerant flow section whose upper and lower ends are closed. A
portion of the second header tank 3 which corresponds to the
outwardly bulging portion 24 serves as a header section. The
thickness of the outside plate 7 is 2 mm or greater. All of the
communication holes 22 and the communication portions 23 of the
intermediate plate 9 form a refrigerant flow section communicating
with the refrigerant flow section within the outwardly bulging
portion 24. In the second header tank 3 as well, the curvature
radius R of a connection portion 26 between the inner wall surface
of the outwardly bulging portion 24 and each of inside surfaces of
the outside plate 7 which are located on the front and rear sides
of the outwardly bulging portion 24 and which extend in the
left-right direction is not greater than 1 mm, preferably, not
greater than 0.5 mm.
[0063] The two header tanks 2 and 3 are manufactured as shown in
FIGS. 7 to 9.
[0064] First, an outside-plate forming metal plate 60, which is
composed of an aluminum brazing sheet having a brazing material
layer on each of opposite sides, is subjected to a press work so as
to form the outside plates 7 each having the outwardly bulging
portions 11A and 11B or the outwardly bulging portion 24 as shown
in FIG. 7. That is, a first press work is performed on the
outside-plate forming metal plate 60 as shown FIG. 7(a) by making
use of a first upper die 61 having a thick-portion forming recess
62 on the lower surface thereof, and a first lower die 63 having a
pair of side-edge restraining projections 64 on the upper surface
thereof, whereby a thick portion 65 is formed at a central portion
with respect to the width direction, the thick portion having a
thickness grater than that of thin portions on the opposite sides
of the thick portion (see FIG. 7(b)). Preferably, the thickness of
the thick portion 65 is 1.05 to 1.5 times the thickness of the thin
portions. When the thickness of the thick portion 65 is less than
1.05 times the thickness of the thin portions, it become difficult
to form the connection portion 26 to have a curvature radius R of 1
mm or less in a second press work, which will be described later.
Further, it is difficult to from the thick portion 65 by press work
to have a thickness greater than 1.5 times the thickness of the
thin portions. In the illustrated example, the thick portion 65 is
formed by the first press work in such a manner that a central
portion of the outside-plate forming metal plate 60 with respect to
the width direction swell upward. However, the method of forming
the thick portion 65 is not limited thereto, and the thick portion
65 may be formed by swelling the central portion of the
outside-plate forming metal plate 60 downward or swelling the
central portion of the outside-plate forming metal plate 60 upward
and downward.
[0065] Subsequently, a second press work is performed on the
outside-plate forming metal plate 60 having the thick portion 65 by
making use of a second upper die 66 and a second lower die 68. The
second upper die 66 has, on the lower surface, a concave portion 67
for forming the outer shape of an outwardly bulging portion 11A
(11B, 24). The second lower die 68 has, on the upper surface, a
convex portion 69 for forming the inner shape of the outwardly
bulging portion 11A (11B, 24), and a pair of side-edge restraining
projections 70. Thus, the outwardly bulging portion 11A (11B, 24)
is formed by making use of the thick portion 65 (see FIG. 7(c)). At
this time, the aluminum material of the outside-plate forming metal
plate 60 flows throughout the space formed between the concave
portion 67 of the second upper die 66 and the convex portion 69 of
the second lower die 68. Thus, the curvature radius R of the
connection portion 26 between the inner wall surface of the
outwardly bulging portion 11A (11B, 24) and the lower surfaces of
the outside plate 7 located on the front and rear sides of the
outwardly bulging portion 11A (11B, 24) and being continuous with
the inner wall surface can be made 1 mm or smaller. In this manner,
the outside plate 7 is manufactured. Notably, the refrigerant inlet
12 and the refrigerant outlet 15 are formed in the outside plate 7
for the first header tank 2.
[0066] Also, an aluminum brazing sheet having a brazing material
layer on each of opposite sides is subjected to a press work so as
to form the inside plates 8 each having the tube insertion holes
18, the cover walls 19, and engaging-portion-forming lugs 21A
extending straight from the cover walls 19. Furthermore, a bare
aluminum material is subjected to a press work so as to form the
intermediate plates 9 each having the communication holes 22, the
stepped portions 25, and the communication portions 23.
[0067] Next, as shown in FIGS. 8 and 9, the three plates 7, 8, and
9 are stacked, and the lugs 21A are bent so as to form the engaging
portions 21 engaged with the outside plate 7, thereby forming a
provisional assembly. Subsequently, the provisional assemblies are
heated at a predetermined temperature, whereby, by use of the
brazing material layers of the outside plate 7 and the brazing
material layers of the inside plate 8, the three plates 7, 8, and 9
are brazed together, the cover walls 19 and the front and rear end
surfaces of the intermediate plate 9 and the outside plate 7 are
brazed together, and the engaging portions 21 and the outside plate
7 are brazed together. Thus are manufactured the two header tanks 2
and 3.
[0068] As shown in FIGS. 10 and 11, the heat exchange tube 4
includes mutually opposed flat upper and lower walls 31 and 32 (a
pair of flat walls); front and rear side walls 33 and 34 which
extend between front and rear side ends, respectively, of the upper
and lower walls 31 and 32; and a plurality of reinforcement walls
35 which are provided at predetermined intervals between the front
and rear side walls 33 and 34 and extend longitudinally and between
the upper and lower walls 31 and 32. By virtue of this structure,
the heat exchange tube 4 internally has a plurality of refrigerant
channels 4a arranged in the width direction thereof.
[0069] The front side wall 33 has a double-wall structure and
includes an outer side-wall-forming elongated projection 36 which
is integrally formed with the front side end of the upper wall 31
in a downward raised condition and extends along the entire height
of the heat exchange tube 4; an inner side-wall-forming elongated
projection 37 which is located inside the outer side-wall-forming
elongated projection 36 and is integrally formed with the upper
wall 31 in a downward raised condition; and an inner
side-wall-forming elongated projection 38 which is integrally
formed with the front side end of the lower wall 32 in an upward
raised condition. The outer side-wall-forming elongated projection
36 is brazed to the two inner side-wall-forming elongated
projections 37 and 38 and the lower wall 32 while a lower end
portion thereof is engaged with a front side edge portion of the
lower surface of the lower wall 32. The two inner side-wall-forming
elongated projections 37 and 38 are brazed together while butting
against each other. The rear side wall 34 is integrally formed with
the upper and lower walls 31 and 32. A projection 38a is integrally
formed on the tip end face of the inner side-wall-forming
projection 38 of the lower wall 32 and extends in the longitudinal
direction of the inner side-wall-forming projection 38 along the
entire length thereof. A groove 37a is formed on the tip end face
of the inner side-wall-forming elongated projection 37 of the upper
wall 31 and extends in the longitudinal direction of the inner
side-wall-forming elongated projection 37 along the entire length
thereof. The projection 38a is press-fitted into the groove
37a.
[0070] The reinforcement walls 35 are formed such that
reinforcement-wall-forming elongated projections 40 and 41, which
are integrally formed with the upper wall 31 in a downward raised
condition, and reinforcement-wall-forming elongated projections 42
and 43, which are integrally formed with the lower wall 32 in an
upward raised condition, are brazed together while the
reinforcement-wall-forming elongate projections 40 and 41 butt
against the reinforcement-wall-forming elongated projections 43 and
42, respectively. The upper wall 31 has the
reinforcement-wall-forming elongated projections 40 and 41, which
are of different projecting heights and are arranged alternately in
the front-rear direction. The lower wall 32 has the
reinforcement-wall-forming elongated projections 42 and 43, which
are of different projecting heights and are arranged alternately in
the front-rear direction. The reinforcement-wall-forming elongated
projections 40 of a long projecting height of the upper wall 31 and
the respective reinforcement-wall-forming elongated projections 43
of a short projecting height of the lower wall 32 are brazed
together. The reinforcement-wall-forming elongated projections 41
of a short projecting height of the upper wall 31 and the
respective reinforcement-wall-forming elongated projections 42 of a
long projecting height of the lower wall 32 are brazed together.
Hereinafter, the reinforcement-wall-forming elongated projections
40 and 42 of a long projecting height of the upper and lower walls
31 and 32 are called the first reinforcement-wall-forming elongated
projections. Similarly, the reinforcement-wall-forming elongated
projections 41 and 43 of a short projecting height of the upper and
lower walls 31 and 32 are called the second
reinforcement-wall-forming elongated projections. A groove 44 (45)
is formed on the tip end face of the second
reinforcement-wall-forming elongated projection 41 (43) of the
upper wall 31 (lower wall 32) and extends in the longitudinal
direction of the second reinforcement-wall-forming elongated
projection 41 (43) along the entire length thereof. A tip end
portion of the first reinforcement-wall-forming elongated
projection 42 (40) of the lower wall 32 (upper wall 31) is fitted
into the groove 44 (45) of the second reinforcement-wall-forming
elongated projection 41 (43) of the upper wall 31 (lower wall 32).
While tip end portions of the first reinforcement-wall-forming
elongated projections 40 and 42 of the upper and lower walls 31 and
32, respectively, are fitted into the respective grooves 45 and 44,
the reinforcement-wall-forming elongated projections 40 and 43 are
brazed together, and the reinforcement-wall-forming elongated
projections 41 and 42 are brazed together.
[0071] The heat exchange tube 4 is manufactured by use of a
tube-forming metal sheet 50 as shown in FIG. 12(a). The
tube-forming metal sheet 50 is formed, by rolling, from an aluminum
brazing sheet having a brazing material layer on each of opposite
sides. The tube-forming metal sheet 50 includes a flat
upper-wall-forming portion 51 (flat-wall-forming portion); a flat
lower-wall-forming portion 52 (flat-wall-forming portion); a
connection portion 53 connecting the upper-wall-forming portion 51
and the lower-wall-forming portion 52 and adapted to form the rear
side wall 34; the inner side-wall-forming elongated projections 37
and 38, which are integrally formed with the side ends of the
upper-wall-forming and lower-wall-forming portions 51 and 52
opposite the connection portion 53 in an upward raised condition
and which are adapted to form an inner portion of the front side
wall 33; an outer side-wall-forming-elongated-projection forming
portion 54, which extends outward from the side end of the
upper-wall-forming portion 51 opposite the connection portion 53;
and a plurality of reinforcement-wall-forming elongated projections
40, 41, 42, and 43, which are integrally formed with the
upper-wall-forming and lower-wall-forming portions 51 and 52 in an
upward raised condition and which are arranged at predetermined
intervals in the width direction of the tube-forming metal sheet
50. The first reinforcement-wall-forming elongated projections 40
of the upper-wall-forming portion 51 and the second
reinforcement-wall-forming elongated projections 43 of the
lower-wall-forming portion 52 are located symmetrically with
respect to the centerline of the width direction of the connection
portion 53. Similarly, the second reinforcement-wall-forming
elongated projections 41 of the upper-wall-forming portion 51 and
the first reinforcement-wall-forming elongated projections 42 of
the lower-wall-forming portion 52 are located symmetrically with
respect to the centerline of the width direction of the connection
portion 53. The projection 38a is formed on the tip end face of the
inner side-wall-forming elongated projection 38 of the
lower-wall-forming portion 52, and the groove 37a is formed on the
tip end face of the inner side-wall-forming elongated projection 37
of the upper-wall-forming portion 51. The groove 44 (45), into
which a tip end portion of the first reinforcement-wall-forming
elongated projection 42 (40) of the lower-wall-forming portion 52
(upper-wall-forming portion 51) is fitted, is formed on the tip end
face of the second reinforcement-wall-forming elongated projection
41 (43) of the upper-wall-forming portion 51 (lower-wall-forming
portion 52).
[0072] The inner side-wall-forming elongated projections 37 and 38
and the reinforcement-wall-forming elongated projections 40, 41,
42, and 43 are integrally formed, by rolling, on one side of the
aluminum brazing sheet whose opposite sides are clad with a brazing
material, whereby a brazing material layer (not shown) is formed on
the opposite side surfaces and tip end faces of the inner
side-wall-forming elongated projections 37 and 38 and the
reinforcement-wall-forming elongated projections 40, 41, 42, and
43; on the peripheral surfaces of the grooves 44 and 45 of the
second reinforcement-wall-forming elongated projections 41 and 43;
and on the vertically opposite surfaces of the upper-wall-forming
and lower-wall-forming portions 51 and 52 and the outer
side-wall-forming-elongated-projection forming portion 54.
[0073] The tube-forming metal sheet 50 is gradually folded at
opposite side edges of the connection portion 53 by a roll forming
process (see FIG. 12(b)) until a hairpin form is assumed. The inner
side-wall-forming elongated projections 37 and 38 are caused to
butt against each other; tip end portions of the first
reinforcement-wall-forming elongated projections 40 and 42 are
fitted into the respective grooves 45 and 44 of the second
reinforcement-wall-forming elongated projections 43 and 41; and the
projection 38a is press-fitted into the groove 37a.
[0074] Next, the outer side-wall-forming-elongated-projection
forming portion 54 is folded along the outer surfaces of the inner
side-wall-forming elongated projections 37 and 38, and a tip end
portion thereof is deformed so as to be engaged with the
lower-wall-forming portion 52, thereby yielding a folded member 55
(see FIG. 12(c)).
[0075] Subsequently, the folded member 55 is heated at a
predetermined temperature so as to braze together tip end portions
of the inner side-wall-forming elongated projections 37 and 38; to
braze together tip end portions of the first and second
reinforcement-wall-forming elongated projections 40 and 43; to
braze together tip end portions of the first and second
reinforcement-wall-forming elongated projections 42 and 41; and to
braze the outer side-wall-forming-elongated-projection forming
portion 54 to the inner side-wall-forming elongated projections 37
and 38 and to the lower-wall-forming portion 52. Thus is
manufactured the heat exchange tube 4.
[0076] While opposite end portions of the heat exchange tubes 4 are
inserted through the respective tube insertion holes 18 of the
inside plates 8 and into the respective communication holes 22 of
the intermediate plates 9 of the header tanks 2 and 3, and end
surfaces of the opposite end portions abut the respective stepped
portions 25 of the intermediate plates 9, the opposite end portions
of the heat exchange tubes 4 are brazed to the respective
peripheral wall surfaces of the tube insertion holes 18 of the
inside plates 8 and to the respective peripheral wall surfaces of
the communication holes 22 of the intermediate plates 9 by
utilization of the brazing material layers of the inside plates 8
and the brazing material layers of the tube-forming metal sheets
50.
[0077] Accordingly, right end portions of an upper-half group of
heat exchange tubes 4 are connected to the first header tank 2 so
as to communicate with the interior of the upper outwardly bulging
portion 11A, and left end portions are connected to the second
header tank 3 so as to communicate with the interior of the
outwardly bulging portion 24. Also, right end portions of a
lower-half group of heat exchange tubes 4 are connected to the
first header tank 2 so as to communicate with the interior of the
lower outwardly bulging portion 11B, and left end portions are
connected to the second header tank 3 so as to communicate with the
interior of the outwardly bulging portion 24.
[0078] Each of the corrugated fins 5 is made in a wavy form from a
brazing sheet; herein, an aluminum brazing sheet, having a brazing
material layer on each of opposite sides.
[0079] The gas cooler 1 is manufactured by the steps of: preparing
the aforementioned two provisional assemblies to be manufactured
into the header tanks 2 and 3, a plurality of the aforementioned
folded members 55, and a plurality of corrugated fins 5; arranging
the two provisional assemblies in such a manner as to be spaced
apart from each other with the inside plates 8 facing each other;
arranging alternately the folded members 55 and the corrugated fins
5; inserting opposite end portions of the folded members 55 through
the respective tube insertion holes 18 of the inside plates 8 and
into the respective communication holes 22 of the intermediate
plates 9 of the two provisional assemblies, and causing the end
surfaces of the opposite end portions to abut the respective
stepped portions 25 of the intermediate plate 9; arranging the side
plates 6 externally of the respective opposite-end corrugated fins
5; arranging the inlet member 13 and the outlet member 16 on the
outwardly bulging portions 11A and 11B, respectively, of the
outside plate 7 used to form the first header tank 2; and brazing
necessary portions of the provisional assemblies as mentioned above
to thereby form the header tanks 2 and 3, brazing necessary
portions of the folded members 55 as mentioned above to thereby
form the heat exchange tubes 4, brazing the heat exchange tubes 4
to the header tanks 2 and 3, brazing the corrugated fins 5 to the
heat exchange tubes 4, brazing the side plates 6 to the respective
corrugated fins 5, and brazing the inlet member 13 and the outlet
member 16 to the outwardly bulging portions 11A and 11B,
respectively.
[0080] The gas cooler 1, together with a compressor, an evaporator,
a pressure-reducing device, and an intermediate heat exchanger for
performing heat exchange between refrigerant from the gas cooler
and refrigerant from the evaporator, constitutes a supercritical
refrigeration cycle. The refrigeration cycle is installed in a
vehicle, for example, in an automobile, as a car air
conditioner.
[0081] In the gas cooler 1 described above, CO.sub.2 from a
compressor flows through the refrigerant inflow channel 14 of the
inlet member 13 and enters the upper outwardly bulging portion 11A
of the first header tank 2 through the refrigerant inlet 12. Then,
the CO.sub.2 dividedly flows into the refrigerant channels 4a of
all the heat exchange tubes 4 in communication with the upper
outwardly bulging portion 11A. The CO.sub.2 in the refrigerant
channels 4a flows leftward through the refrigerant channels 4a and
enters the outwardly bulging portion 24 of the second header tank
3. The CO.sub.2 in the outwardly bulging portion 24 flows downward
through the interior of the outwardly bulging portion 24 and
through the communication portions 33 of the intermediate plate 9;
dividedly flows into the refrigerant channels 4a of all the heat
exchange tubes 4 in communication with the lower outwardly bulging
portion 11B; changes its course; flows rightward through the
refrigerant channels 4a; and enters the lower outwardly bulging
portion 11B of the first header tank 2. Subsequently, the CO.sub.2
flows out of the gas cooler 1 via the refrigerant outlet 15 and the
refrigerant outflow channel 17 of the outlet member 16. While
flowing through the refrigerant channels 4a of the heat exchange
tubes 4, the CO.sub.2 is subjected to heat exchange with the air
flowing through the air-passing clearances in the direction of
arrow X shown in FIG. 1, thereby being cooled.
[0082] FIG. 13 shows another method of manufacturing the outside
plates 7 of the two header tanks 2 and 3.
[0083] First, a first press work is performed on an outside-plate
forming metal plate 60, which is composed of an aluminum brazing
sheet having a brazing material layer on each of opposite sides as
shown in FIG. 13(a), by use of a first upper die 80 and a first
lower die 82. The first upper die 80 has, on the lower surface, a
concave portion 81 having a depth greater than the height of the
outwardly bulging portion 11A (11B, 24) as measured on the outer
side thereof. The first lower die 82 has, on the upper surface, a
convex portion 83 having a height greater than the height of the
outwardly bulging portion 11A (11B, 24) as measured on the inner
side thereof. Thus, a preliminary bulging portion 84 having a
bulging height greater than the outwardly bulging portion 11A (11B,
24) is formed (see FIG. 13(b)).
[0084] Subsequently, a second press work is performed on the
outside-plate forming metal plate 60 by making use of a second
upper die 85 and a second lower die 89. The second upper die 85
has, on the lower surface, a concave portion 86 for forming the
outer shape of the outwardly bulging portion 11A (11B, 24), and a
pair of projections 88 having cutting blades 87 at their lower ends
and restraining the outside-plate forming metal plate 60 from
opposite sides with respect to the width direction. The second
lower die 89 has, on the upper surface, a convex portion 90 for
forming the inner shape of the outwardly bulging portion 11A (11B,
24). Before the preliminary bulging portion 84 is formed into the
outwardly bulging portion 11A (11B, 24), opposite side edge
portions of the outside-plate forming metal plate 60 are cut by
means of the cutting blades 87 of the projections 88 of the second
upper die 85. After this cutting, the preliminary bulging portion
84 is formed into outwardly bulging portion 11A (11B, 24) by the
concave portion 86 and the convex portion 90, while the
outside-plate forming metal plate 60 having the preliminary bulging
portion 84 is restricted from opposite sides with respect to the
width direction by the projections 88 of the second upper die 85
(see FIG. 13(c)). At this time, the aluminum material of the
outside-plate forming metal plate 60 flows throughout the space
formed between the concave portion 86 of the second upper die 85
and the convex portion 90 of the second lower die 89. Thus, the
curvature radius R of the connection portion 26 between the inner
wall surface of the outwardly bulging portion 11A (11B, 24) and the
lower surfaces of the outside plate 7 located on the front and rear
sides of the outwardly bulging portion 11A (11B, 24) and being
continuous with the inner wall surface can be made 1 mm or smaller.
In this manner, the outside plate 7 is manufactured.
[0085] In the above-described embodiment, each outside plate 7 is
formed of an aluminum brazing sheet having a brazing material layer
on each of opposite sides, and the outside plate 7 and the
intermediate plate 9 are brazed together by making use of the
brazing material layer of the outside plate 7. However, the manner
of brazing the outside plate 7 and the intermediate plate 9 is not
limited thereto, and the outside plate 7 and the intermediate plate
9 may be brazed as follows. Each outside plate 7 is formed of an
aluminum brazing sheet having a brazing material layer only on an
outer surface in the left-right direction (a surface facing
opposite to the corresponding intermediate plate 9); the
intermediate plate 9 is formed of an aluminum brazing sheet having
a brazing material layer only on an outer surface in the left-right
direction (a surface facing the outside plate 7); and the outside
plate 7 and the intermediate plate 9 are brazed together by making
use of the brazing material layer of the intermediate plate 9.
[0086] In the above-described embodiment, the heat exchanger of the
present invention is applied to a gas cooler of a supercritical
refrigeration cycle. However, the heat exchanger of the present
invention may be applied to an evaporator of the above-mentioned
supercritical refrigeration cycle. This evaporator, together with a
compressor, a gas cooler, a pressure-reducing device, and an
intermediate heat exchanger for performing heat exchange between
refrigerant from the gas cooler and refrigerant from the
evaporator, constitutes a supercritical refrigeration cycle which
uses a supercritical refrigerant such as CO.sub.2. This
refrigeration cycle is installed in a vehicle, for example, in an
automobile, as a car air conditioner. Moreover, the method of
manufacturing outside plates according to the present invention can
be applied to manufacture of the outside plates of the header tanks
of the evaporator of the above-mentioned supercritical
refrigeration cycle.
[0087] Although CO.sub.2 is used as a supercritical refrigerant of
a supercritical refrigeration cycle in the above-described
embodiments, the refrigerant is not limited thereto, but ethylene,
ethane, nitrogen oxide, or the like may be alternatively used.
[0088] The above-described embodiment uses, for forming the heat
exchange tube 4, a folded member 55 which is formed by bending a
tube-forming metal sheet in the form of an aluminum brazing sheet
having a brazing material layer on each of opposite sides. However,
the present invention is not limited thereto. For example, an
aluminum extrudate having a brazing material layer on its outer
surface may be used to form the heat exchange tube 4.
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