U.S. patent application number 09/748352 was filed with the patent office on 2001-05-10 for multi-flow type heat exchanger.
Invention is credited to Baba, Kazuhito, Sugawara, Masatsugu, Sunaga, Tsutomu, Yamamoto, Toshiaki.
Application Number | 20010000879 09/748352 |
Document ID | / |
Family ID | 27469466 |
Filed Date | 2001-05-10 |
United States Patent
Application |
20010000879 |
Kind Code |
A1 |
Sugawara, Masatsugu ; et
al. |
May 10, 2001 |
Multi-flow type heat exchanger
Abstract
A heat exchanger of the multi-flow type is provided with baffle
members which are adapted to impart a zigzagging flow to the
heat-exchange fluid in motion inside a flat tube and define, in
conjunction with the inner wall of the flat tube, a flow path of a
cross-sectional area having an equivalent diameter in the range of
0.4 to 1.5 mm. This heat exchanger excels in heat exchange ability
and in facility of manufacture and assemblage.
Inventors: |
Sugawara, Masatsugu; (Tokyo,
JP) ; Baba, Kazuhito; (Tokyo, JP) ; Yamamoto,
Toshiaki; (Tokyo, JP) ; Sunaga, Tsutomu;
(Tokyo, JP) |
Correspondence
Address: |
Richard L. Schwaab
FOLEY & LARDNER
Washington Harbour
3000 K Stree, N.W., Suite 500
Washington
DC
20007-5109
US
|
Family ID: |
27469466 |
Appl. No.: |
09/748352 |
Filed: |
December 27, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09748352 |
Dec 27, 2000 |
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07977041 |
Nov 16, 1992 |
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07977041 |
Nov 16, 1992 |
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07703607 |
May 21, 1991 |
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07703607 |
May 21, 1991 |
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07392724 |
Aug 11, 1989 |
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Current U.S.
Class: |
165/67 ; 165/177;
165/69; 29/890.053 |
Current CPC
Class: |
F28F 3/025 20130101;
F28D 1/0435 20130101; F28D 1/0316 20130101; F28D 2021/0094
20130101; F28F 9/002 20130101; F28F 2001/027 20130101; F28D
2021/0084 20130101; Y10T 29/49391 20150115; F28D 1/05391 20130101;
F28D 1/0391 20130101 |
Class at
Publication: |
165/67 ; 165/69;
165/177; 29/890.053 |
International
Class: |
F28F 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 12, 1988 |
JP |
63-106782 UM |
Aug 12, 1988 |
JP |
63-106783 UM |
Aug 12, 1988 |
JP |
63-106784 UM |
Aug 12, 1988 |
JP |
63-106785 UM |
Claims
What is claimed is:
1. A heat exchanger of the multi-flow type comprising a pair of
header pipes (1, 2 having a annular cross section fit for flow of
heat-exchanger fluid and disposed parallelly as separated by a
prescribed length (.lambda.), a multiplicity of flat tubes (5)
disposed between said header pipes (1, 2) in such a manner as to
intercommunicate them, and baffle members (G) adapted to impart a
zigzagging stirring motion to said heat-exchanger fluid in motion,
which heat exchanger is characterized by the fact that the flow
paths defined by said baffle members (G) and the inside walls of
said flat tubes possess a cross-sectional area having an equivalent
diameter in the range of 0.4 to 1.5 mm.
2. A heat exchanger according to claim 1, wherein said baffle
members (G) comprise inner fins and said inner fins (20) are
corrugated so as to divide the flow paths inside said flat tubes
into a plurality of small flow paths and give rise to corrugated
parts (h) raised between slits placed parallelly at prescribed
intervals (s) in the direction perpendicular to the direction of
the flow of said heat-exchanger fluid so that the edge surfaces (E)
of the corrugated parts of the preceding stage are positioned
between the corrugated parts of the subsequent stage.
3. A mounting structure for the heat exchanger according to claim
1, wherein one-side ends (1a, 2a) of said header pipes (1, 2) are
fastened to engaging parts (30) formed in an object (B1) serving as
a base for attachment and the other-side ends (1b 2b) of said
header pipes (1, 2) are attached to said object through the medium
of retaining brackets (31) adapted to retain in place said
other-side ends (1b, 2b).
4. A heat exchanger according to claim 1, wherein elastic members
(32b) are interposed between the one-side ends (1a, 2a) of said
header pipes (1, 2) and said engaging parts of said object (B1) and
between said retaining brackets (31) and the other-side ends (1b,
2b) of said header pipes (1, 2).
5. A heat exchanger of the multi-flow type comprising a pair of
header pipes (1, 2) having a annular cross section fit for flow of
heat-exchanger fluid and disposed parallelly as separated by a
prescribed length (.lambda.), a multiplicity of flat tubes (5)
disposed between said header pipes (1, 2) in such a manner as to
intercommunicate them, and baffle members (G) adapted to impart a
zigzagging stirring motion to said heat-exchanger fluid in motion,
which heat exchanger is characterized by the fact that said flat
tubes (5) are formed by joining two halved flat tubes (5a, 5b),
said halved flat tubes (5a,5b) are each provided therein with a
plurality of dimples (50a, 50b) projected symmetrically toward each
other so as to partition partially the flow path inside said flat
tube (5), the apexes (51a, 51b) of said dimples (50a, 50b) are
joined to each other in a width in the range of 1 to 2 mm, said
dimples are spaced with a fixed pitch (Pd) in the range of 2 to 4
mm, and the inside thickness (t) of said tubes is in the range of
0.5 to 1.7 mm.
6. A heat exchanger according to claim 5, wherein said flat tubes
(5) are formed by folding one plate material.
7. A heat exchanger according to claim 5, wherein said flat tubes
(5) are formed by joining two halved flat tubes (5a, 5b).
8. A heat exchanger according to claim 7, wherein said flat tubes
(5) have formed in the terminal parts of said halved flat tubes
(5a, 5b) such abutting parts (61a, 61b) as adapted to conform to
the peripheral edges of said engaging holes in said header
pipes.
9. A heat exchanger according to claim 7, wherein said halved flat
tubes (5a, 5b) have formed in the terminal parts thereof such
inserting parts (62a, 62b) as possessed of an outer shape
conforming to the shape of said engaging holes (60) and such
budding parts (61a, 61b) as adapted to abut the peripheral edges of
said engaging holes (6).
Description
BACKGROUND OF THE INVENTION
1. 1. Field of the Invention
2. This invention relates to improvements in and concerning a
multi-flow type heat exchanger to be incorporated in an automobile
air conditioner.
3. 2. Description of the Prior Art
4. Among the heat exchanger recently proposed for use as in
condensers of automobile air conditioners are included those of the
multi-flow type which are configured as illustrated in FIG. 34 (as
disclosed in U.S. Pat. No. 4,615,385 and Japanese Patent
Application Disclosure SHO 62(1987)-175,588, for example).
5. The heat exchanger of this multi-flow type is provided with a
pair of header pipes 1, 2 separated by a prescribed length .lambda.
from each other and disposed parallelly to each other. An inlet
tube 3 for introducing a heat-exchanger fluid such as a refrigerant
is fitted to the inlet side header pipe 1 and an outlet tube 4 for
discharging the heat-exchanger fluid is fitted to the other outlet
side header pipe 2. Between the two header pipes 1, 2, a
multiplicity of flat tubes 5 are installed so as to
intercommunicate these two header pipes 1, 2. Thus, the
heat-exchanger fluid flowing in through the inlet side header pipe
1 advances in the form of a plurality of parallel flows and flows
into the outlet side header pipe 2. On the opposed side surfaces of
the two header pipes 1, 2, bulged parts 6 of the shape of a dome
are formed as illustrated in FIG. 35 for the purpose of enhancing
the heat exchangers' strength to resist pressure.
6. In FIGS. 34 and 35, the reference numeral "7" denotes a
corrugated fin for transfer of heat, the reference numerals "8 and
9" denote blank covers, and the reference numeral "10" denotes a
reinforcing plate.
7. In the flat tube 5, an inner fin 11 whose cross section taken
perpendicularly to the axis thereof is corrugated with a prescribed
pitch p as illustrated in FIG. 36, is inserted and fixed in place.
The inner fin 11 serves the purpose of partitioning the flow path r
of the flat tube 5 and giving rise to a plurality of independent
small flow paths 12 therein.
8. In this heat exchanger H of the multi-flow type, therefore, the
heat-exchanger fluid which flows in the inlet side header pipe 1
advances collectively in the form of a plurality of parallel flows
in the direction of the outlet side header pipe 2 and, at the same
time, advances in the form of parallel flows severally inside the
small flow paths 12.
9. The heat exchanger H of the multi-flow type, for the sake of
enhancing the capacity thereof for exchange of heat, has the small
flow paths 12 each so adapted that the equivalent diameter (the
diameter of a flow path having a circular cross-sectional area
equaling the cross-sectional area of the small flow path) thereof
has a predescribed value. Specifically, in consideration of the
pressure drop occurring in the flowing air, the resistance offered
to the flow of the heat-exchanger fluid and the heat-exchange
efficiency, the heat transfer area is adjusted to a prescribed
value so as to heighten the whole heat exchange efficiency of the
heat exchanger. There are heat exchangers which use the so-called
serpenine tubes (flat tubes of an elliptical section extrusion
molded so as to form a plurality of flow paths inside). The heat
exchanger of the multi-flow type described above, as compared with
the heat exchanger of the type using the serpentine tubes, has the
merit high pressure-resisting capacity, small size, and light
weight ascribable to the formation of bulged parts 9 on the header
pipes 1. 2 in addition to enjoying the advantages of small
thickness of tube, low resistance to the fluid in motion, and high
capacity for exchange of heat.
10. The heat exchanger of the multi-flow type, however, is
problematic in terms of performance and in terms of
manufacture.
11. First as concerns the performance, the inner fin 11 is soldered
in place within a furnace in such a manner as to define the flow
paths 5 inside the flat tube 5 as illustrated in FIG. 36. The small
flow paths 12 consequently formed herein extent straightly from the
leading ends to the trailing ends thereof. The heat-exchanger fluid
flows just straightly inside the flat tube 5 and has no possibility
of being stirred while in motion therein. It is not inconceivable
that the portion of the heat-exchanger fluid which flows along the
central part of the cross section of the small flow paths 12 just
advances through the interior of the flat tube 5. The
heat-exchanger fluid does not wholly contribute to the action of
exchange of heat.
12. The portions of the heat-exchanger fluid flowing inside the
small flow paths 12 defined by the inner fin 11, while in motion
between the header pipes 1, 2, are not intermingled with one
another but simply advanced without being allowed to manifest the
heat exchange ability to a sufficient extent.
13. In connection with this point, Japanese Patent Application
Disclosure SHO 61(1986)-295,494 and Japanese Utility Model
Application Disclosure SHO 62(1987)-39,182 disclose a corrugated
inner fin so configured that the waves thereof are staggered by a
prescribed pitch. This inner fin is capable of imparting a
zigzagging flow to the heat-exchanger fluid and incapable of
manifesting the heat exchange ability fully satisfactorily.
14. The heat exchanger of the multi-flow type is further
problematic in terms of manufacture.
15. The inner fin 11 is soldered within the furnace in conjunction
with all of the other component members of the heat exchanger
including the flat tube 5. In this case, the step of applying flux
to the ridge parts 11a of the inner fin 11 is required to precede
the step of entering the component members of the heat exchanger in
the furnace. In this step, however, since the inner fin 11 is
corrugated as illustrated in FIG. 37, the flux adhering to the
ridge parts 11a trickles down the sloped surfaces and collects in
the groove parts 11b. As the result, the flux adheres in an
insufficient amount to the surface of the ridge parts 11a which
require the flux to be deposited most thickly and the work of
soldering consequently becomes extremely difficult.
16. Further, the heat exchanger H of the multi-flow type, as
disclosed in U.S. Pat. No. 4,651,816, is fixed in place by causing
brackets 13 attached fast as by soldering to the header pipes 1, 2
to be bolted to the car body or to other heat exchanger such as,
for example, the radiator in the engine cooling cycle. The brackets
13 are generally made of aluminum. After the mounting positions for
the brackets which are variable with vehicles are corrected by the
use of jigs, for example, the brackets are soldiered integrally
within the heating furnace at the same time that the flat tubes 5
and the corrugated fins 7 are soldered or they are first soldered
and then fixed in place as by the TIG welding.
17. Incidentally, when the fixation is effected by the work of
soldering as described above, it is generally difficult to solder
the brackets while maintaining the accuracy of the mounting
positions. The TIG welding proves to be disadvantageous in terms of
productivity and cost because the number of steps of process is
large.
18. Japanese Utility Model Application Disclosure SHO
61(1986)-110,017 discloses a structure for fixing the heat
exchanger in place without being welded. Since the heat exchanger
in this disclosure has no use for the header pipes, the number of
component parts is unduly large and the assembly of such component
parts consumes much time and labor.
SUMMARY OF THE INVENTION
19. This invention, conceived in the urge to eliminate the
disadvantages of the prior art described above, aims to provide a
heat exchanger of the multi-flow type which allowed to give through
stirring to the heat-excharger fluid without entailing any
appreciable increase in the resistance offered by the fluid paths
and enabled to excel in heat exchange performance and in facility
of manufacture and assemblage by providing flat tubes therein with
baffle members adapted to impart a zigzagging flow to the
heat-exchanger fluid and, at the same time, giving to the flow
paths defined by the baffle members and the inner walls of the falt
tubes a cross-sectional area having an equivalent diameter in the
range of 0.4 to 1.5 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
20. FIG. 1 is a partially cutaway perspective view illustrating an
embodiment of this invention.
21. FIG. 2 is a cross section illustrating a flat tube in the
embodiment in the process of shaping.
22. FIG. 3 is a cross section of the flat tube of the
embodiment.
23. FIG. 4 is a perspective view of an inner fin.
24. FIG. 5 and FIG. 6 are graphs showing the results of tests
performed on the embodiment.
25. FIG. 7 is a front view illustrating a modification of the heat
exchanger mentioned above.
26. FIG. 8 is an exploded perspective view illustrating the
essential part of a mounting structure for the heat exchanger.
27. FIG. 9 is a cross section taken through FIG. 8 along the line
IX-IX.
28. FIG. 10 is a cross section taken through FIG. 8 along the line
X-X.
29. FIG. 11 is an exploded perspective view illustrating the
essential part of another mounting structure for the heat exchanger
mentioned above.
30. FIG. 12 is a cross section taken through FIG. 11 along the line
XII-XII.
31. FIG. 13 is an exploded perspective view illustrating yet
another mounting structure for the heat exchanger mentioned
above.
32. FIG. 14 is a cross section illustrating a flat tube for use in
another embodiment of this invention in the process of shaping.
33. FIG. 15 is a cross section illustrating the same flat tube in
the process of bending.
34. FIG. 16 (A) is a perspective view of the flat tube and FIGS. 16
(B) and (C) are cross section taken through FIG. 16 (A)
respectively along the line B-B and the line C-C.
35. FIG. 17 is a perspective view illustrating another embodiment
of the flat tube.
36. FIG. 18 and FIG. 19 are a perspective view and a cross section
illustrating yet another typical flat tube.
37. FIGS. 20 to 25 are graphs showing the results of tests
performed on the heat exchanger of this invention.
38. FIGS. 26 and 27 and FIGS. 28 and 29 are pairs each of a
perspective view and a cross section illustrating yet other flat
tubes.
39. FIG. 30 is an exploded perspective view illustrating the state
of connection between the flat tube mentioned above and header
pipes.
40. FIG. 31 and FIG. 32 are perspective views illustrating other
typical terminal parts of the flat tube mentioned above.
41. FIG. 33 is an exploded perspective view of the flat tube
appearing in FIG. 32.
42. FIG. 34 is a perspective view of the conventional heat
exchanger.
43. FIG. 35 is a cross section of FIG. 36 is a cross section of the
flat tube of the conventional heat exchanger mentioned above.
44. FIG. 37 is a perspective view of an inner fin of the
conventional heat exchanger mentioned above.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
45. Now, one embodiment of this invention will be described with
reference to the accompanying drawings.
46. FIG. 1 is a partially cutaway perspective view illustrating an
embodiment of this invention, FIG. 2 is a cross section
illustrating a flat tube of the embodiment in a state prior to
shaping, FIG. 3 is a cross section illustrating the flat tube of
the embodiment in a state after shaping, and FIG. 4 is a
perspective view of the essential part of an inner fin. In these
diagrams, the component parts which have equivalents in FIGS. 34 to
37 are denoted by the same reference numerals.
47. In the heat exchanger H of the multi-flow type, an inlet side
header pipe 1 of a parallelly cross section fitted with an inlet
tube 3 for admitting a heat-exchanger fluid in motion and an outlet
side header pipe 2 of a parallelly cross section fitted with an
outlet tube 4 for discharging the heat-exchanger fluid are
separated by a prescribed length from each other and disposed
annular to each other. Between these header pipes 1, 2, a
multiplicity of flat tubes 5 are disposed so as to intercommunicate
the header pipes. The arrangement of these component parts is
similar to that illustrated in FIG. 34. These header pipes 1, 2 are
made of aluminum and have a wall thickness of 1.5 mm.
48. First, the flat tube 5 will be explained.
49. The flat tube 5, as illustrated in FIG. 2, is produced by
shaping a flat sheet material in a form having a flat U cross
section perpendicular to the axis, deforming terminal flanges 21 of
the sheet material in the direction of the arrow, and sitting in an
inner fin 20 in the U-shaped sheet, then sticking the two flanges
21, 21, and between said inner fin 20 and the inside wall of said
U-shaped sheet, and then welding tham.
50. However, said weld stage can do it lump together as a whole,
after assembling the beaer pipes 1,2, the carrugated fin 7, and
said U-shaped sheet with the inner fin 20. This coustructing method
is similar another embodiment.
51. Now, the inner fin 20 disposed inside each of the flat tubes 5
and intended as a baffle member G whose function consists in
baffling the flow of the refrigerant will be described.
52. This inner fin 20 is shaped in a form whose cross section
perpendicular to the axis is corrugated at a prescribed pitch p as
illustrated in FIGS. 3 and 4, so as to divide the flow path r
inside the flat tube 5 into a plurality of small independent flow
paths 12. The diameter of the fluid in motion inside these small
flow paths 12 is so set that the equivalent diameter determined in
connection with the pressure drop in the flowing air, the
resistance to the flow of the heat-exchanger fluid, and the
efficiency of exchange of heat will fall in a prescribed range of
about 0.4 to 1.5 mm, preferably in the neighborhood of 0.7 mm.
53. Particularly when the corrugated parts h of the prescribed
pitch p mentioned above are formed in the inner fin 20 of the
present embodiment, the corrugated parts h are raised between slits
placed parallelly at prescribed intervals s as staggered in the
direction perpendicular to the direction of the flow of the
heat-exchanger fluid (the direction of the arrow shown in FIG. 4)
so that the edge surfaces E of the corrugated parts h.sub.2 in the
second stage are positioned at the centers of the corrugated parts
h.sub.1 in the first stage, the edge surfaces E of the corrugated
parts h.sub.3 in the third stage at the centers of the corrugated
parts h.sub.2 in the second stage, and so on.
54. In this case, the prescribed intervals s mentioned above may be
equal to or different from one another. The ridges of these
corrugated parts may be in the general shape of a rectangle as
illustrated in FIG. 3 or in the natural shape of a wave as
illustrated in FIG. 37.
55. In the arrangement described above, since the edge surfaces E
manifest the edge effect (the heat exchange effect produced at the
sharp edge portions resembling the edges of knifes is prominent as
compared with the effect produced at any other portion; hence the
designation "edge effect") and the edge surfaces E are present in a
large number throughout the entire length of the flat tube 5, the
exchange of heat between the heat-exchanger fluid and the air
proceeds very efficiently and the ability of the heat exchanger as
a whole to effect exchange of heat is heightened notably. Further,
since these edge surfaces E are so distributed that the edge
surfaces of the corrugated parts h.sub.2 in the second stage are
positioned at the centers of the corrugated parts h.sub.1 in the
first stage, the portions of the heat-exchanger fluid which have
flowed down the small flow paths 12 formed by the corrugated parts
h.sub.1 of the first stage collide against and stirred by the edge
surfaces E of the corrugated parts h.sub.2 of the second stage.
Owing to the effect of this agitation, the exchange of heat is
carried out very efficiently and the ability of the heat exchanger
as a whole to effect exchange of heat is enhanced to a notable
extent.
56. When the heat exchanger of the present embodiment was tested
for performance of radiation under the condition using a wind
velocity of 5 m/s, the results were as shown in FIG. 5.
57. Comparison of the test results obtained of the conventional
heat exchanger using a corrugated inner fin (indicated by the
dotted line in the diagram) and those obtained of the heat
exchanger of the present invention (indicated by the full line in
the diagram) reveals that the difference in capacity for radiation
was about 1500 Kcal/h where the equivalent diameter was 0.75 mm and
about 1,200 Kcal/h where the equivalent diameter was 1.2 mm,
clearly implying that in either of the cases, the performance of
the zigzagged inner fin 20 of the present invention was about 15%
higher than the corrugated inner fin of the conventional heat
exchanger. When the heat exchanger of this invention was tested for
the resistance offered by the flow paths to the heat-exchanger
fluid used as the refrigerant, the results which were as shown in
FIG. 6 indicate that the most desirable equivalent diameter was
approximately in the range of 0.4 to 1.5 mm.
58. The embodiment described above is so configured that the edge
surfaces E of the corrugated parts h.sub.2 of the second stage are
positioned at the centers of the corrugated parts h.sub.1 of the
first stage. It is not an indispensable requisite, however, that
the edge surfaces E of the corrugated parts h.sub.2 of the second
stage should be positioned at the centers of the corrugated parts
h.sub.1 of the first stage. Optionally, the edge surfaces E of the
corrugated parts h.sub.2 of the second stage may be positioned
between the adjacent corrugated part h.sub.1 of the first
stage.
59. The corrugated parts mentioned above are staggered in the
direction perpendicular to the direction of the flow of the
heat-exchanger fluid. The perpendicular direction is not critical
for the staggering. Optionally, the staggering may be made in an
oblique direction.
60. This invention may be embodied in a heat exchanger which is
configured as illustrated in FIG. 7. In this heat exchanger, a
header pipe 1 is divided into an upper header pipe 1a and a lower
header pipe 1b by a partition plate 22 disposed at the center of
the header pipe 1 in the vertical direction thereof, so that the
heat-exchanger fluid flowing in through an inlet tube 3 advances
through the upper header pipe 1a, a flat tube 5, a header pipe 2, a
flat tube 5, and the lower header pipe 1b and flows out of an
outlet tube 4. This heat exchanger has one partition plate 22
disposed inside the header pipe 1 to effect one U-turn flow. Of
course, it may have a plurality of partition plates 22 disposed
inside the two header pipes 1, 2 (indicated by a broken line in
FIG. 7) so as to effect a plurality of U-turn flows.
61. In the manufacture of the heat exchanger of this multi-flow
type, a multiplicity of flat tubes 5 are parallelly disposed
between the header pipes 1, 2, corrugated fins 7 are interposed
between adjacent flat tubes 5, inner fins 20 are disposed inside
the flat tubes 5, and the resultant assembly is placed in a furnace
and the component parts thereof are soldered collectively. In the
manufacture, even when the liquid flux applied to the projected
parts 11a of the inner fin 20 inserted in the flat tube 5 flows
down the sloped surfaces of the projected parts 11a, it is allowed
to flow through the holes o (FIG. 4) formed where the corrugated
parts h are raised along slits in the inner fin 20 and eventually
reach and adhere to the outer periphery of the inner fin 20 on the
opposite side, with the result that the flux remaining on the
projected parts' side and the flux reaching the opposite side will
be distributed so as to coat the whole inner fin almost uniformly.
Thus, the union between the inner fin 20 and the flat tube 5 is
effected throughout their entire volumes with notably increased
strength.
62. In the attachment of the heat exchanger configured as described
above to the car body or some other similar object, the use of the
rigidity of the header pipes 1, 2 enables this attachment to be
effected with high accuracy with great ease.
63. When the lower end of the heat exchanger is attached to the
front cross member B1 of the car body and the upper end thereof to
the radiator core panel B2 of the car body as illustrated in FIG.
8, cylindrical blind elastic members 32a of rubber material formed
to conform to the outer contours of the lower ends (one-side; ends)
1a, 2a of the header pipes 1, 2 are slipped over the lower ends 1a,
2a of the header pipes 1, 2 and the elastic members 32a now capping
the lower ends 1a, 2a of the header pipes 1, 2 are inserted into
engagement with engaging parts 30 formed to conform to the outer
contours of the elastic members 32a. The upper ends (the other-side
ends) 1b, 2b of the header pipes 1, 2 are fixed in place by
allowing the retaining brackets 31 each provided with a retaining
part 31a possessing an inner peripheral shape roughly conforming to
the outer contours of the header pipes 1, 2 and bent in a
semicircular cross section and a mounting part 31b having
perforated therein an oblong hole 33 for insertion of a bolt 35 to
nip elastic members 32b possessing an inner peripheral shape
conforming to the outer contours of the header pipes 1, 2, and
inserting the bolts 35 through the oblong holes 33 into helical
engagement with thread holes 34 formed in the radiator core panel
B2.
64. The ealstic members 32a, 32b mentioned above are not always
required to be made of a rubber material but may be made of a
foamed material of polyurethane resin, for example. The engaging
parts 30 of the front cross member B1 are desired to be perforated
with a drain hole 36. Optionally, the elastic members 32a, 32b may
be omitted and the header pipes 1a, 2a may be directly joined to
the front cross member B1 and the header pipes 1b, 2b may be
directly connected to the retaining brackets 31. In consideration
of possible errors involved in the manufacture of header pipes 1, 2
of the heat exchanger, the engaging parts of the front cross member
B1, and the threaded holes 34 in the radiator core panel B2,
however, the interposition of the elastic members 32a, 32b capable
of suitably absorbing such errors proves to be highly
desirable.
65. In the attachment of the heat exchanger to a given object by
the use of the mounting structure of the present embodiment
configured, as illustrated in FIG. 8, the cylindrical blind elastic
members 32a of rubber material possessing an inner shape conforming
to the outer contours of the header pipes 1, 2 are inserted into
the one ends 1a, 2a of the header pipes. The ends 1a, 2a capped
with the elastic members 32a are inserted into engagement with the
engaging parts 30 formed in the front cross member B1 and
possessing an inner shape conforming to the outer contours of the
elastic members 32a. Then, the retaining brackets 31 each provided
with the retaining part 31a possessing an inner peripheral shape
substantially conforming to the outer contours of the header pipes
1, 2 and bent in the shape of a semicircular cross section and the
mounting part 31b having perforated therein the oblong hole 33 for
insertion of the bolt 35 are pressed against the other-side ends
1b, 2b of the header pipes in such a manner as to nip the elastic
members 32b possessing an inner peripheral shape conforming to the
outer contours of the header pipes 1, 2. Thereafter, the bolts 35
are inserted through the oblong holes 33 of the mounting parts 31b
of the retaining brackets 31 and into the threaded holes 34, to
complete the attachment.
66. As described above, the one-side ends 1a, 2a of the header
pipes of the heat exchanger are inserted into engagement with a
given object through the medium of the elastic members 32a and, at
the same time, the other-side ends 1b, 2b of the header pipes are
attached to a given object with the retaining brackets 31
(accessorial parts) through the medium of the elastic members 31b.
Owing to this arrangement, the work of attachment to the object can
be carried out very easily. Moreover, this arrangement is capable
of absorbing possible errors of manufacture.
67. FIG. 11 is an exploded perspective view illustrating the
essential part of a modified mounting structure for the heat
exchanger and FIG. 12 is a cross section taken through FIG. 11
along the line XII-XII.
68. This mounting structure for the heat exchanger typifies a case
in which the object for attachment of the heat exchanger is a car
body and the lower ends 1a, 2a of the header pipes 1, 2 are
fastened to the front cross member B1 and the upper ends 1b, 2b of
the header pipes 1, 2 to an upper rail B3. Into the upper ends 1b,
2b of the header pipes 1, 2 of the heat exchanger, roughly
cylindrical elastic members 32b possessing inner shapes conforming
to the outer contours of the header pipes 1, 2 are inserted.
Further, these elastic members 32b are inserted into the retaining
brackets 31 each comprising a roughly cylindrical retaining part
31a possessing an inner shape conforming to the outer contours of
the elastic members 31b and a mounting part 31 having an oblong
hole 33 perforated therein. When the heat exchanger provided with
this mounting structure is attached to the car body, for example,
the lower ends 1a, 2a of the header pipes are inserted into the
elastic members 32a and simultaneously inserted into engagement
with the engaging parts 30 of the front cross member B1. Then, the
elastic members 32b are inserted into the upper ends 1b, 2b of the
header pipes and further the retaining brackets 31 are inserted
therein and the bolts 35 are inserted into the oblong holes 33
perforated in the retaining brackets 31. Subsequently, the bolts 35
are screwed to the tapped holes 34 formed in the upper rail B3, to
complete the attachment of the heat exchanger to the car body.
69. FIG. 13 is an exploded perspective view illustrating yet
another modification of the mounting structure for the heat
exchanger. In this case, the mounting structure is adapted so that
the heat exchanger (condenser for an automobile air conditioner) H
is attached to a radiator 40 and the radiator 40 is attached to the
car body. The engaging parts 30 for insertion of the lower ends 1a,
2a of the header pipes 1, 2 of the heat exchanger H are formed
beneath a radiator 40, an object meant as a base for mounting, and
the retaining brackets 31 are inserted into the upper ends 1b, 2b
of the header pipes 1, 2 so as to permit penetration of the bolts
42 for connecting the radiator 40 to fan shrouds 41. The attachment
of the heat exchanger H, the radiator 40, and the fan shroud 41 to
the car body is attained by first inserting the lower ends of the
header pipes 1, 2 of the heat exchanger H into the engaging parts
30 of the radiator 40, then inserting the brackets 31 into the
upper ends 1b, 2b of the header pipes 1, 2, tying the retaining
brackets 31, the radiator 40, and the fan shroud 41 together with
bolts thereby fastening the heat exchanger H to the raditor 40, and
subsequently attaching the assembled components H, 40, and 41 to
the car body as with bolts 43. In the diagram, the reference
numeral 44 denotes a projection formed beneath the radiator and the
reference numeral 45 devotes a bracket attached to the car body and
adapted to receive the aforementioned projection.
70. In the arrangement described above, since the heat exchanger H,
the radiator 40, and the fan shroud 41 are integrally joined to the
car body, the work of assembling the car body can be carried out
with improved efficiency.
71. FIG. 14 illustrated yet another embodiment of this invention,
in which the baffle member G mentioned above is not formed
separately of the flat tube like the inner fin 20 but is formed of
the flat tube itself.
72. This flat tube 5 is obtained by forming a plurality of dimples
50a, 50b in a flat plate with roll R.sub.1 and R.sub.2 as
illustrated in FIG. 14, then folding the halved flat tubes 5a, 5b
roward each other as illustrated in FIG. 15 into a state indicated
by the broken line, and joining the outer edges and the opposed
dimples as by soldering.
73. The halved flat tubes 5a, 5b are formed by the rolling
operation using the two rolls R.sub.1, R.sub.2 possessing cross
sections indicated by a dashed line in FIG. 14. These two forming
rolls R.sub.1, R.sub.2 are formed in shapes corresponding to the
shapes of the halved flat tubes 5a, 5b and they have formed therein
protuberances 50 and recesses 51 corresponding to the dimples 50a,
50b. When a flat aluminum plate is passed between the two forming
rolls R.sub.1, R.sub.2, therefore, the halved flat tubes 5a, 5b can
be easily produced. Since the two halved flat tubes 5a, 5b are
symmetrically identical with each other, it suffices to prepare one
set of forming rolls R.sub.1, R.sub.2 for the production of halved
flat tubes. This fact contributes to economizing the equipment
cost. When the formed flat plate is folded along the central
portion over itself as illustrated in FIG. 15, the dimples 50a, 50b
thrust out as opposed to each other at the positions corresponding
to those of the two halved flat tubes 5a, 5b as indicated by the
broken line in FIG. 15, with the apexes 51a, 51b thereof coming
into tight contact with each other. Then, by soldering the
contiguous apexes 51a, 51b at the time that the outer edges are
soldered, the flat tube illustrated in FIG. 16 (A) is completed.
This flat tube 5 has, in the two halved flat tubes 5a, 5b, formed
dimples 50a, 50b spaced with a fixed pitch Pd as illustrated in
FIG. 16 (B).
74. In this flat tube 5, a plurality of small flow paths 12a (FIG.
16B refers) are defined by the dimples 50a, 50b and flow paths 12b
(FIG. 16 C refers) are formed in the portions containing none of
the dimples 50a, 50b, describing a cross section perpendicular to
the axis, and having a thickness equal to the inner thickness t of
the tube and a width denoted by W. The dimples 50a, 50b may have a
circular shape as illustrated in FIG. 16 (A) or an elliptical shape
as illustrated in FIG. 17. The small flow paths defined by these
dimples 50a, 50b are desired to be formed with due considation to
the prescribed equivalent diameter mentioned above. Of course, the
flat tube 5 may be produced by the use of an electric welded tube
of the kind illustrated in FIG. 17.
75. The two halved flat tubes 5a, 5b mentioned above may be formed
separately of each other as illustrated in FIG. 18 and FIG. 19.
Those illustrated in FIG. 18 and FIG. 19 have folded flanges 52a,
52b formed along the edges of the two halved flat tubes 5a, 5b in
such a manner that the flanges 52a, 52b abut each other when the
two halved flat tubes 5a, 5b are joined to each other. In this
arrangement, the area available for the application of solder is
increased and the strength of union by the soldering is enhanced
and the work of soldering is improved.
76. The inside thickness t of the flat tube 5 and the pitch Pd
between the adjacent dimples 50a, 50b are desired to be determined
at suitable values in accordance with various conditions of the
heat exchanger of this invention such as capacity for exchange of
heat and resistance to pressure. It has been established by
experiments that the thickness, t, the pitch, Pd, and the width, A,
of joint at the apex of dimple are desirably in the following
ranges.
77. t=0.5 to 1.7 mm
78. Pd=2 to 4 mm
79. A=1 to 2 mm.
80. The preferred ranges of these magnitudes will be described in
detail below with reference to the graphs of FIGS. 20 to 25 showing
pertinent test results.
81. FIG. 20 is a graph showing the heat exchange capacity of a heat
exchanger formed of a flat tube 5 having a width, W, of 17 mm, an
inner tube thickness, t, of 1.1 mm, and a tube wall thickness of
0.4 mm as the function of the dimple pitch, Pd, of the heat
exchanger.
82. FIG. 21 is a graph showing the change of pressure resistance of
the flat tube 5 as the function of the dimple pitch Pd as
determined of the same flat tube as described above.
83. FIG. 22 is a graph showing the change of the resistance of the
flow paths inside the flat tube 5 having a width, W, of 17 mm, an
inner tube thickness, t, of 1.1 mm, and a tube wall thickness of
0.4 mm as the function of the dimple pitch Pd in the heat exchanger
using the flat tube 5.
84. FIG. 23 is a graph showing the change of the heat exchange
capacity of the heat exchanger using the flat tube 5 having a
width, W, of 17 mm, a tube wall thickness of 0.4 mm, and a dimple
pitch, Pd, of 3 mm as the function of the tube wall thickness,
t.
85. It is noted from FIGS. 20 to 22 that the ability and pressure
resistance of the heat exchanger were improved by setting the
dimple pitch, Pd, at a small value. When the dimple pitch, Pd, was
set at an unduly small value, however, there arose the possibility
that the size of the plurality of flow paths defined by the dimples
50a, 50b would decrease excessively and the resistance to the flow
of the fluid subjected to heat exchange would conversely increase
as shown in FIG. 21. These results indicate that the dimple pitch,
Pd, is preferably in the range of 2 to 4 mm. It is noted from FIG.
23 that the ability of the heat exchanger increased in proportion
as the inside thickness, t, of the flat tube 5 decreased. Again in
this case similarly to the case of the dimple pitch, Pd, the
resistance to the flow of the fluid subjected to heat exchange
increased and the load required for supply of the fluid increased
when the inside thickness, t, of the flat tube decreased
excessively. It may well be concluded from these results that the
inside thickness, t, of the flat tube is suitable in the range of
0.5 to 1.7 mm.
86. In order for the heat exchanger to resist the breaking
pressure, the width, A, of joint between the leading ends of the
dimples 50a, 50b is desired to be as large as permissible. As
concerns the ratio of adhesion of the corrugated fin 7 to the flat
tube 5, however, the width, A, is desired to be small. The
experiments conducted to determine the effects of the width, A, of
joint between the leading ends of the dimples 50a, 50b demonstrated
that the width was optimal in the range of 1 to 2 mm as shown in
FIG. 24 and FIG. 25. These data on the width, A, are applicable to
the soldered tube shown in FIG. 16 A and to the electric welded
tube shown in FIG. 17.
87. The manufacture of the heat exchanger of the multi-flow type of
the present embodiment configured as described above is started by
shaping the halved flat tubes 5a, 5b by the rolling technique
mentioned previously and, at the same time, forming the plurality
of dimples 50a, 50b. Then, the flux is applied on the inner and
outer sides of the halved flat tubes 5a, 5b before these halved
flat tubes are joined.
88. However the joint by welding can do it after assembling the
beader pipes 1,2, the corrugated fin 7 and soon. Subsequently, the
two halved flat tubes 5a, 5b are joined to each other, placed in
the heating furnace, and silvered therein. In this case, since the
application of the flux is carried out before the halved flat tubes
5a, 5b are joined to each other, the works involved are very easy
to perform. Further, since the flux is uniformly applied inside the
halved flat tubes 5a, 5b, the possibility of the flux clogging the
small flow paths to be formed between the dimples 50a, 50b is nil.
The opposite ends of a plurality of flat tubes 5 obtained as
described above are inserted into the corrugated fin 7 between
them, and the ends of said flat tubes 5 are insurted in the
engaging holes (not shown) bored in the header pipes 1, 2, and
welding lump together as a whole, the corrugated fins 7 are
interposed between the flat tubes 5 and the corrugated fins 7 are
integrally joined by soldering.
89. The dimples 50a, 50b described above may be formed in richly
varied shaped. For example, by forming a plurality of substantially
parallel beads 53a in one halved flat tube 52, forming a plurality
of beads 53b intersecting the aforementioned beads 53a in the other
halved flat tube 5b, and then joining these two halved flat tubes
5a, 5b as illustrated in FIGS. 26 to 29 similarly to the embodiment
described above, flow paths may be partitioned inside the flat tube
5 by virtue of the intersection of the beads 53a, 53b as
illustrated in FIGS. 27 and 29. The difference between the
embodiment illustrated in FIGS. 26 and 27 and the embodiment
illustrated in FIGS. 28 and 29 resides in the joining structure for
the opposed edges of these two halved flat tubes 5a, 5b.
90. In order to ensure safe union between the header pipes 1, 2 and
the terminal parts of the flat tubes each consisting of halved flat
tubes 5a, 5b separately formed by the rolling technique, the
terminal parts are desired to be formed as illustrated in FIG.
30.
91. The flat tube 5 has, in the terminal parts thereof, formed
abutting parts 61a adapted to make close contact with the header
pipes 1, 2, so that the flat tubes 5 and the header pipes 1, 2 will
be held in intimate contact with each other while they are being
soldered in the furnace. The abutting parts 61a each consist of
flanges formed one each in the terminal parts of the halved flat
tubes 5a, 5b. They are formed by the pressing technique after the
halved flat tubes 5a, 5b have been formed by rolling in the shape
having a U cross section perpendicular to the axis. They are formed
in a shape conforming to the outer peripheral surfaces of the
header pipes 1, 2 surrounding the engaging holes 60 bored in the
header pipes 1, 2. The flow paths to be formed inside the flat tube
5 when the two halved flat tubes 5a, 5b are joined substantially
conform to the engaging holes 60 mentioned above.
92. Since this embodiment has no use for the inner fin 20, it
obviates the necessity for the step of inserting the inner fin 20
into the flat tube 5 and the step of crushing the flat tube 5 after
the insertion of the inner fin 20 therein. It further permits
prevention of the flat tube from the clogging ascribable to the
improvement in the work of application of the flux. This embodiment
also facilitates the work of assembling the heat exchanger and
heightens the productivity in the manufacture of heat
exchangers.
93. The flat tube 5 may be configured as illustrated in FIG. 31.
This flat tube 5 is provided at each of the terminal parts thereof
with inserting parts 62a, 62b conforming in shape to the engaging
holes 60 and abutting parts 61a, 61b conforming to the peripheral
edges of the engaging holes. This flat tube 5 is obtained,
similarly to that of FIG. 30, folding a flat plate in a shape
having a U cross section perpendicular to axis while the flat plate
is being rolled to produce two halved flat tubes 5a, 5b, forming
the flange parts 52a, 52b at the opposite terminals of the folded
flat plate, and simultaneously forming a plurality of dimples 50a,
50b in the flat portions of the halved flat tubes 5a, 5b. Then, the
flange parts 52a, 52b in the lateral terminal parts of the halved
flat tubes 5a, 5b are partially cut off as illustrated in FIG. 31
and the two halved flat tubes 5a, 5b are joined. As the result, the
terminal surfaces of the flange parts 52a, 52b come into fast
contact with the engaging holes 60 and, at the same time, the
inserting parts 62a, 62b of the flat tubes 5a, 5b having the flange
parts thereof 52a, 52b partially out off are inserted into the
engaging holes 60.
94. When the inserting parts 62a, 62b and the abutting parts 61a,
61b are formed in the opposite terminal parts of the flat tube 5 as
described above, therefore, the sizes of the engaging holes 60
allowed for insertion are fixed owing to the positioning of the
abutting parts 61a, 61b at the time that the flat tube is attached
to the engaging holes of the header pipes 1, 2. As the result, the
work of assemblage is facilitated to a great extent.
95. In the flat tube 5 illustrated in FIGS. 32 and 33, the terminal
parts of one, 5b, of the halved flat tubes formed by rolling
similarly to those of FIG. 31 are folded back in the direction away
from the flange parts 52a, 52b by the pressing technique and the
terminal parts of the other halved flat tube 5a are folded back in
a size enough to wrap in the outer surface of the terminal part of
the aforementioned halved flat tube 5b. Here, the folded parts
constitute themselves the inserting parts 62a, 62b for insertion
into the engaging holes 60 and the terminal surfaces of the folded
flange parts constitute themselves the abutting parts 61a, 61b for
contact with the peripheral edges of the engaging holes 60. When
the two halved flat tubes 5a, 5b are soldered within the furnace in
the state joined and the flat tubes 5 are attached to the header
pipes 1, 2, the inserting parts 62a, 62b in the terminal parts of
the flat tube 5 are inserted into the header pipes 1, 2 until the
abutting parts 61a, 61b collide against the peripheral edges of the
engaging holes.
96. Also in this arrangement, the sizes of the engaging holes
allowed for insertion are fixed in consequence of the positioning
of the abutting parts. As the result, the work of assemblage is
facilitated to a great extent.
97. The embodiments described above are desired to be used mainly
for condensers in automobile air conditioners. This invention is
not limited to this particular use but may be used for evaporators
or for automobile radiators.
98. As described above, this invention contemplates imparting a
zigzagged flow to the heat-exchanger fluid in motion inside the
flat tube by means of baffle members and further defining the
cross-sectional area of the flow paths to an equivalent diameter in
the range of 0.4 to 1.5 mm and consequently ensures thorough
stirring of the refrigerant without entailing any appreciable
addition to the resistance of the flow paths to the fluid in
motion. The heat exchanger, therefore, is enabled to enjoy a
notable improvement in the heat exchange efficiency.
99. As regards the formation of the baffle members, the fact is
that the baffle members are formed as integral parts of the flat
tube itself allows a decrease in the number of component parts and
consequent facilitation of the manufacture of the heat exchanger
and proves to be advantageous from the economic point of view.
100. Further, since this invention contemplates causing one-side
ends of the header pipes of the heat exchanger to be inserted into
engagement with an object intended as a base for attachment through
the medium of elastic members and, at the same time, the other-side
ends of the header pipes to be attached to the object with
retaining brackets as accessorial parts through the medium of
elastic members, the work of attaching the heat exchanger to the
object can be carried out very easily and the possible errors of
manufacture can be absorbed.
101. The apexes of the dimples in the two halved flat tubes are
joined in a width in the range of 1 to 2 mm. These dimples are
spaced with a prescribed pitch in the range of 2 to 4 mm. The
inside thickness of the flat tube is selected in the range of 0.5
to 1.7 mm. Owing to the incorporation of these dimples, the flat
tube has no use for the inner fin. Thus, the flat tube of this
configuration obviates the necessity for the step of inserting the
inner fin into the flat tube and the step of crushing the flat tube
after the insertion of the inner fin. It also precludes the
possible clogging of the flat tube due to the improvement in the
work of application of the flux. The heat exchanger enjoys high
heat exchange capacity and is easy to manufacture.
102. One flat tube is obtained by joining two halved flat tubes. In
the terminal parts of the halved flat tubes, there are formed
abutting parts conforming to the peripheral edges of the engaging
holes in the header pipes. Thus, the work of positioning the flat
tubes is easy to carry out and the work of assemblage is performed
with enhanced efficiency.
* * * * *