U.S. patent application number 11/367611 was filed with the patent office on 2006-09-14 for heat exchanger and flat tubes.
Invention is credited to Peter Ambros, Wolfgang Knecht, Andreas Stolz, Roland Strahle.
Application Number | 20060201663 11/367611 |
Document ID | / |
Family ID | 36579311 |
Filed Date | 2006-09-14 |
United States Patent
Application |
20060201663 |
Kind Code |
A1 |
Strahle; Roland ; et
al. |
September 14, 2006 |
Heat exchanger and flat tubes
Abstract
A heat exchanger including a plurality of longitudinal flat
tubes stacked together with space between the broad sides of
adjacent tubes, and inlet and outlet collecting tanks. The inlet
collecting tank distributes a first medium into the tubes, and has
a wall extending around the periphery of one end the stack of flat
tubes over a selected longitudinal section, the wall having at
least one of an inlet and outlet for a second medium distributed in
the space between the stacked tubes. The outlet collecting tank
receives the first medium from the tubes. Longitudinal internal
inserts in the flat tubes are metallically connected to the broad
sides of the associated flat tube. At least one row of cutouts is
between the longitudinal ends of the internal inserts and in the
selected longitudinal section, with the row of cutouts extending
substantially across the broad width of the insert.
Inventors: |
Strahle; Roland;
(Unterensingen, DE) ; Ambros; Peter;
(Kusterdingen, DE) ; Knecht; Wolfgang; (Stuttgart,
DE) ; Stolz; Andreas; (Walddorfhaslach, DE) |
Correspondence
Address: |
WOOD, PHILLIPS, KATZ, CLARK & MORTIMER
500 W. MADISON STREET
SUITE 3800
CHICAGO
IL
60661
US
|
Family ID: |
36579311 |
Appl. No.: |
11/367611 |
Filed: |
March 3, 2006 |
Current U.S.
Class: |
165/164 ;
165/157 |
Current CPC
Class: |
F28F 9/0219 20130101;
F28D 9/0031 20130101; F28F 9/001 20130101; F28F 2001/027 20130101;
F28F 3/027 20130101; F28F 3/044 20130101 |
Class at
Publication: |
165/164 ;
165/157 |
International
Class: |
F28D 7/10 20060101
F28D007/10 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2005 |
DE |
DE 102005010493.2 |
Claims
1. A heat exchanger, comprising: a plurality of longitudinal flat
tubes stacked togetherwith space between the broad sides of
adjacent tubes; an inlet collecting tank distributing a first
medium into said tubes, said inlet collecting tank having a wall
extending around the periphery of one end said stack of flat tubes
over a selected longitudinal section, said wall having at least one
of an inlet and outlet for a second medium distributed in said
space between said stacked tubes; an outlet collecting tank
receiving said first medium from said tubes; longitudinal internal
inserts in the flat tubes, each internal insert being metallically
connected to the broad sides of the associated flat tube; and at
least one row of cutouts between the longitudinal ends of said
internal inserts and in said selected longitudinal section, said
row of cutouts extending substantially across the broad width of
the insert.
2. The heat exchanger of claim 1, wherein the internal insert is a
sheet corrugated in the longitudinal and transverse directions and
said at least one row of cutouts includes at least two rows of
cutouts with a connecting insert portion between said rows of
cutouts.
3. The heat exchanger of claim 2, wherein the corrugated sheet
includes wave flanks, and said connection insert portion is in said
wave flanks.
4. The heat exchanger of claim 2, wherein said rows of cutouts
extend no more than one third (1/3) of the total length of the
internal insert and the remaining length of the internal insert has
substantially no cutouts.
5. The heat exchanger of claim 2, wherein the size and shape of the
cutouts and the connecting insert portion is variable.
6. The heat exchanger of claim 2, further comprising a row of end
cutouts open on the end of the internal insert in said selected
longitudinal section, and an end connecting insert portion between
said row of end cutouts and an adjacent row of cutouts.
7. The heat exchanger of claim 6, wherein said internal insert
includes fingers in the crests and valleys of the corrugated sheet
adjacent opposite sides of said end cutouts, and said fingers are
soldered on the inside wall of the associated flat tube.
8. The heat exchanger of claim 1, wherein said at least one row of
cutouts includes at least two rows of cutouts with a connecting
insert portion between said rows of cutouts, and further comprising
at least one rupture site in said connecting insert portion.
9. The heat exchanger of claim 1, wherein said tubes comprise two
flat tube halves connected on their longitudinal edges.
10. The heat exchanger of claim 1, further comprising outwardly
projecting embossings on the broad sides of said tubes, said
embossings defining said space between the broad sides of adjacent
tubes in said stack of tubes.
11. The heat exchanger of claim 1, wherein said collecting tank
wall has deformations adapted to stabilize said tank while
providing elasticity during alternating temperature loads.
12. The heat exchanger of claim 1, wherein said selected
longitudinal section is bounded by first and second connection
planes at one end of the stack of tubes, and said one inlet or
outlet for the second medium is in said collecting tank wall
between said two planes.
13. The heat exchanger of claim 12, further comprising a tube plate
connected to said collecting tank wall at said first connection
plane, said tube plate having connectors for the ends of the stack
of flat tubes.
14. The heat exchanger of claim 12, further comprising an
intermediate plate having the peripheral contour of the stack of
flat tubes and connected to wall in the first connection plane.
15. The heat exchanger of claim 12, wherein said second connection
plane is defined by a contour cut in the collecting tank wall and
matching the peripheral contour of the stack of flat tubes.
16. The heat exchanger of claim 12, wherein said contour cut in the
collecting tank wall has slits matching an end flange on said flat
tubes, and protrusions closing furrows at the space between
adjacent flat tubes.
17. The heat exchanger of claim 12, wherein the broad sides of the
heat exchanger tubes include protrusions in the region of the first
connection plane to divide the flow of the second medium in the
space between adjacent tubes.
18. The heat exchanger of claim 1, wherein said inlet collecting
tank includes a diffuser for said first medium, and one of an inlet
and outlet for said second medium is in said selected longitudinal
section.
19. The heat exchanger of claim 1, wherein the heat exchanger is an
exhaust heat exchanger cooled with liquid in the exhaust gas
recirculation system of vehicles.
20. The heat exchanger of claim 1, wherein the heat.exchanger is a
charge air cooler.
21. A tube for use with a heat exchanger with said tube including
an end section connectable to a wall of at least one collecting
tank, comprising: a longitudinal flat tube with broad sides; and a
longitudinal internal insert metallically connected to the tube
broad sides and including at least one row of cutouts between the
longitudinal ends of said internal insert in said end and extending
substantially across the broad width of the insert.
22. The tube of claim 21, wherein the internal insert is corrugated
and said at least one row of cutouts includes at least two rows of
cutouts with a connecting insert portion between said rows of
cutouts.
23. The tube of claim 22, wherein the corrugated internal insert
has wave flanks extending between opposite broad sides of the tube,
and said connecting insert portion is primarily in said wave
flanks.
24. The tube of claim 22, wherein said rows of cutouts extend over
no more than one third (1/3) of the total length of the internal
insert.
Description
CROSS REFERENCE TO RELATED APPLICATION(S)
[0001] Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
[0003] Not applicable.
TECHNICAL FIELD
[0004] The present invention is directed toward heat exchangers,
and particularly toward flat tube heat exchangers subject to
alternating temperature loads.
BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEMS POSED BY THE
PRIOR ART
[0005] Heat exchangers are, of course, old in the art in a variety
of configurations. One such heat exchanger type includes an inlet
collecting tank which distributes a medium to flat heat exchanger
tubes and an outlet collecting tank which accepts the medium from
the flat heat exchanger tubes. An internal insert is arranged in
the flat heat exchanger tubes, with the insert being metallically
connected to the two broad sides of the heat exchanger tube.
[0006] In one particular form, the collecting tank has a wall that
extends around the periphery of the end of a stack of heat
exchanger tubes and over a certain length section of the heat
exchanger tubes, in which the wall has at least one inlet and/or
one outlet for the other medium which flows between the heat
exchanger tubes. This particular form of heat exchanger and heat
exchanger tube described above are described in the not previously
published European Patent Application with Application No. EP 040
27 604.0, in which a slit on the end of the internal insert or a
conical cutout open toward the end is provided. In accordance with
that description, both expedients led to a noticeable improvement
with respect to compensation of alternating temperature loads.
[0007] However, even with the improvement of that described
structure, it is still desirable to provide heat exchangers and
heat exchanger tubes which can even betterwithstand the enormous
alternating temperature loads encountered, for example, in an
exhaust heat exchanger in an exhaust gas recirculation system.
[0008] The present invention is directed toward overcoming one or
more of the problems set forth above.
SUMMARY OF THE INVENTION
[0009] In one aspect of the present invention, a heat exchanger is
provided, including a plurality of longitudinal flat tubes stacked
together with space between the broad sides of adjacent tubes, and
inlet and outlet collecting tanks. The inlet collecting tank
distributes a first medium into the tubes, and has a wall extending
around the periphery of one end the stack of flat tubes over a
selected longitudinal section, the wall having at least one of an
inlet and outlet for a second medium distributed in the space
between the stacked tubes. The outlet collecting tank receives the
first medium from the tubes. Longitudinal internal inserts in the
flat tubes are metallically connected to the broad sides of the
associated flat tube. There is at least one row of cutouts between
the longitudinal ends of the internal inserts and in the selected
longitudinal section, with the row of cutouts extending
substantially across the broad width of the insert.
[0010] In one form of this aspect of the present invention, the
internal insert is a.sheet corrugated in the longitudinal and
transverse directions and the at least one row of cutouts includes
at least two rows of cutouts with a connecting insert portion
between the rows of cutouts. In a further form, the corrugated
sheet includes wave flanks, and the connection insert portion is in
the wave flanks. In another further form, the rows of cutouts
extend no more than one third (1/3) of the total length of the
internal insert and the remaining length of the internal insert has
substantially no cutouts. In still another further form, the size
and shape of the cutouts and the connecting insert portion is
variable. In yet another further form, a row of end cutouts is open
on the end of the internal insert in the selected longitudinal
section, and an end connecting insert portion is between the row of
end cutouts and an adjacent row of cutouts, and in a still further
form the internal insert includes fingers in the crests and valleys
of the corrugated sheet adjacent opposite sides of the end cutouts,
with the fingers soldered on the inside wall of the associated flat
tube.
[0011] In another form of this aspect of the present invention, the
at least one row of cutouts includes at least two rows of cutouts
with a connecting insert portion between the rows of cutouts, and
further includes at least one rupture site in the connecting insert
portion.
[0012] In still another form of this aspect of the present
invention, the tubes are two flat tube halves connected on their
longitudinal edges.
[0013] In yet another form of this aspect of the present invention,
outwardly projecting embossings are on the broad sides of the
tubes, with the embossings defining the space between the broad
sides of adjacent tubes in the stack of tubes.
[0014] In another form of this aspect of the present invention, the
collecting tank wall has deformations adapted to stabilize the tank
while providing elasticity during alternating temperature
loads.
[0015] In still another form of this aspect of the present
invention, the selected longitudinal section is bounded by first
and second connection planes at one end of the stack of tubes, and
the one inlet or outlet for the second medium is in the collecting
tank wall between the two planes. In a further form, a tube plate
is connected to the collecting tank wall at the first connection
plane, with the tube plate having connectors for the ends of the
stack of flat tubes. In another further form, an intermediate plate
having the peripheral contour of the stack of flat tubes is
connected to wall in the first connection plane. In still another
further form, the second connection plane is defined by a contour
cut in the collecting tank wall and matching the peripheral contour
of the stack of flat tubes. In yet another further form, the
contour cut in the collecting tank wall has slits matching an end
flange on the flat tubes and also has protrusions closing furrows
at the space between adjacent flat tubes. In another further form,
the broad sides of the heat exchanger tubes include protrusions in
the region of the first connection plane to divide the flow of the
second medium in the space between adjacent tubes.
[0016] In another form of this aspect of the present invention, the
inlet collecting tank includes a diffuser for the first medium, and
one of an. inlet and outlet for the second medium is in the
selected longitudinal section.
[0017] In still another form of this aspect of the present
invention, the heat exchanger is an exhaust heat exchanger cooled
with liquid in the exhaust gas recirculation system of
vehicles.
[0018] In yet another form of this aspect of the present invention,
the heat exchanger is a charge air cooler.
[0019] In another aspect of the present invention, a tube is
provided for use with a heat exchanger with the tube including an
end section connectable to a wall of at least one collecting tank,
including a longitudinal flat tube with broad sides, and a
longitudinal internal insert metallically connected to the tube
broad sides and including at least one row of cutouts between the
longitudinal ends of the internal insert in the end and extending
substantially across the broad width of the insert.
[0020] In one form of this aspect of the present invention, the
internal insert is corrugated and the at least one row of cutouts
includes at least two rows of cutouts with a connecting insert
portion between the rows of cutouts. In a further form, the
corrugated internal insert has wave flanks extending between
opposite broad sides of the tube, and the connecting insert portion
is primarily in the wave flanks. In another further form, the rows
of cutouts extend over no more than one third (1/3) of the total
length of the internal insert.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a face view of one embodiment of a heat exchanger
incorporating the present invention;
[0022] FIG. 2 is a perspective view of a collecting tank of the
FIG. 1 embodiment.
[0023] FIG. 3 is a perspective view on one end of one embodiment of
a heat exchanger tube incorporating the present invention;
[0024] FIG. 4 is a perspective view on one end of a second
embodiment of a heat exchanger tube incorporating the present
invention;
[0025] FIG. 5 is a perspective view of an intermediate plate usable
with the present invention;
[0026] FIG. 6 is a partially exploded perspective view of one end
of a heat exchanger including the FIG. 5 intermediate plate;
[0027] FIG. 7 is a perspective view of the FIG. 6 heat exchanger,
with portions broken away to show the internal inserts of the heat
exchanger tubes;
[0028] FIGS. 8 to 14 are perspective views illustrating the ends of
different embodiments of tube internal inserts incorporating the
present invention;
[0029] FIG. 15 is a cutout of a part of the core of the charge air
cooler of FIG. 16; and
[0030] FIG. 16 is a partially exploded view of an air-cooled charge
air cooler incorporating the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] The practical examples illustrated in FIGS. 1-7 involve
exhaust heat exchangers, such as may be advantageously incorporated
in the exhaust gas recirculation system of a vehicle in a manner
not shown, and which use the coolant of the vehicle engine as the
cooling medium. The heat exchanger can be used with the same
advantages, for example, as a charge air cooler cooled with coolant
or for other purposes, especially where high alternating
temperature loads occur.
[0032] It should also be appreciated that the present invention may
also be advantageously used, for example, with heat exchangers
which are U-shaped, in which the inlet 20 and the outlet 21 are
situated on the same collecting tank 24a.
[0033] In the Figures showing the practical examples, however, heat
exchangers having collecting tanks on both ends of the stack of
heat exchanger tubes 26 are depicted. As a result, in the heat
exchanger depicted in FIG. 1, the exhaust flows into the left
collecting tank 24b, is distributed to and flows through the paths
28 in the heat exchanger tubes 26, and then leaves the heat
exchanger via the other (right) collecting tank 24b. The coolant,
on the other hand, enters the inlet 20 on the right collecting tank
24a, is distributed to the flow channels 30 which are arranged
between the heat exchanger tubes 26 (FIG. 6 or 7) and leaves the
heat exchanger via the outlet 21 provided in the left collecting
tank 24a.
[0034] The inlet 20 and the outlet 21, in this practical example,
have a roughly rectangular cross-section. Advantageously, a mount
36, produced by deformation from sheet metal, was provided in each
case on the collecting tank 24a, which extends around three sides
of the collecting tank 24a and is firmly soldered to it. The mount
36 has the inlet 20 or the outlet 21 and an appropriate sealing
groove 38, so that the heat exchanger can be flanged directly to a
connection plane of a unit (not shown) and therefore fastened to it
and simultaneously "supplied" with coolant.
[0035] The stack of heat exchanger tubes 26 may advantageously be
covered by an upper and lower reinforcement plate 76 (FIG. 7)
because the sheet thickness of the heat exchanger tubes 26 is
relatively small. Both protection against the mechanical effect on
tubes 26 and higher stability of the entire heat exchanger can be
achieved by this.
[0036] FIG. 2 shows the collecting tank 24a in a first variant in a
perspective view, as present twofold in the practical example from
FIG. 1, apart from the cross-sectional shape of the inlet 20 and
outlet 21 (which are roughly rectangular in FIG. 1 and round in
FIG. 2).
[0037] FIG. 3 shows one of the seven heat exchanger tubes 26
present there. The wall 40 of collecting tank 24a has deformations
44, which, by the way, can also be provided in the wall 40 of
collecting tank 24b (FIG. 1). In addition, there are two connection
planes 50 and 54 between the wall 40 and the stack of heat
exchanger tubes 26. In one connection plane 54, direct connection
of the wall 40 to the tube stack is provided at an opening 60,
which represents the peripheral contour of the stack, which
includes slits 64 and protrusions 66. Each slit 64 accommodates a
tube edge flange 70 (see FIG. 3), and upper and lower gradations 74
accommodate the reinforcement plates 76.
[0038] In the other connection plane 50, on the other hand, an
indirect connection to the wall 40 is present, since, in this
practical example, an intermediate tube plate 78 is provided. For
this purpose, the edge of wall 40 has a gradation at 80 (see FIGS.
2 and 6), so that the tube plate 78 has a seat with a stop in the
wall 40. The already mentioned slits 64 are also situated in the
contour of tube plate 78 and serve the same purpose there.
[0039] The edge of the opening 60 in the wall 40 and the edge of
perforations of the tube plate 78 are formed with only a slight
passage 82 (see FIG. 2) pointing toward the center of the heat
exchanger, which contributes to achievement of a perfect soldered
connection with the tubes 26 even with a relatively limited
thickness of the wall 40, a perfect soldered connection with tubes
26 can be achieved. The passage 82 may be formed via corresponding
design of the punching tool for production of the opening 60 and is
therefore feasible without additional expense. Openings 60
according to this design are advantageously present in all
practical examples of the exhaust heat exchanger, even if the other
figures do not show it in detail.
[0040] As also shown in FIG. 3, a longitudinal section or region 86
of the heat exchanger tubes 26 lies between the two connection
plates 50 and 54. The heat exchanger tubes 26 are combined in the
stack direction 88 (FIG. 6) into a stack of heat exchanger tubes
26. The reinforcement plates 76 (FIG. 7) are added on opposite
sides of the stack. As further described below, internal inserts 90
are inserted in each case into heat exchanger tubes 26, which
consist of two identical flat tubes halves 26a, 26b joined by bent
brackets 92 on the edge flange 70. Such tube structure is
particularly cost-effective and is characterized by high process
reliability, especially during soldering. The stack is combined via
the longitudinal section 86 of the heat exchanger tubes to the
collecting tank 24a, in which each edge flange 70 of each heat
exchanger tube 26 comes to lie in the connection plane 54 in a slit
64 present there and, in the other connection plane 50, sits in a
slit 64 of tube plate 78 present there (see above).
[0041] It should be appreciated that flat heat exchanger tubes as
described herein are tubes which have a smaller and a larger inside
dimension, and therefore include not only those with parallel broad
sides but also include, for example, heat exchanger tubes with an
oval cross-section. Moreover, it should be appreciated that flat
heat exchanger tubes according to the present invention also
include those formed by two plates forming the two broad sides in
which the two narrow sides of the tubes are represented by a rod or
the like inserted between the plates. Such designs are found in
many applications of heat exchangers, and are also encountered, for
example, in fuel cell systems.
[0042] FIGS. 6 and 7 show one end 94 of the heat exchanger, where
it is apparent that a flow channel 30 is formed in each case
between the heat exchanger tubes 26 through which the coolant can
flow. Specifically, as shown in FIGS. 3-4, the identical flat tube
halves 26a, 26b have longitudinal projections or embossings 100
along their edges which close off a flow channel 30 between two
assembled heat exchanger tubes 26. The embossings 100 seal off the
flow channels so that an essentially housingless design may be
achieved, which design is characterized by economic use of material
with the highest efficiency of heat transfer. On the broad sides
102 of heat exchanger tubes 26, additional spaced projections 104
are also present and, in the vicinity of the connection planes 50,
a row with protrusions 106 may be advantageously provided to make
flow of the coolant which enters or emerges in that vicinity (see
the arrows in FIG. 4) uniform.
[0043] As is further clearly shown in FIG. 7, corrugated internal
inserts 90 are situated in the heat exchanger tubes 26. The
internal inserts 90 may have wave flanks 110 corrugated in the
longitudinal direction and transverse direction (see the
longitudinal section on the right of FIG. 7.
[0044] In addition, the wave flanks 110 have cutouts 120 and
intermediate connectors 130. In the FIG. 7 embodiment, seven rows
134 of round cutouts 120 are apparent, which are separated from
each other by an intermediate connector 130. It should be
appreciated that length changes in the stack direction 88 of heat
exchanger tubes 26, occurring because of temperature changes, are
permitted or compensated by this. In particular, the distinctness
of the improvement in resistance to alternating temperature loads
is surprising.
[0045] Since the loads in exhaust heat exchangers reach the limit
of what can be accomplished with ordinary materials (stainless
steel, aluminum) and joining techniques (particularly considering
cost-effective manufacturing methods of mass production) due to the
level of the temperature differences and the frequency of the
temperature alternations, the inventors hereof concerned themselves
with demonstrating the advantages of the present invention with
additional variations thereof.
[0046] In that regard, in one variation the protrusions 106 and the
flat tubes halves 26a, 26b were modified so that, in the region of
the connection plane 50, groups of protrusions 106 were
concentrated (see FIG. 4) to divert the incoming coolant so that a
significant part of it is initially directed to the connection
plane 54 before it can flow further into flow channels 30. Better
temperature equalization is achieved by this and therefore the
objective of improving the capability, relative to. alternating
temperature loads, is also served.
[0047] In an alternative embodiment, the tube plate 78 (see FIG. 2)
is replaced by an intermediate plate 140 (see FIGS. 5 and 6), with
the flat tube halves 26a, 26b modified for this purpose (see FIG.
4). Specifically, additional projections 144 extend across the
broad sides 102 of the ends 94 of the flat tube halves 26a, 26b,
which projections 144 whose a height coinciding with the height of
the embossings 100 running along the longitudinal sides. The
additional projections 144 of adjacent heat exchanger tubes 26 lie
against each other and each closes off a flow channel 30. A
traditional tube plate 78 with connectors 150 can therefore be
dispensed with. As shown in the mentioned figures, the intermediate
plate 140, in similar fashion to the wall 40 in the other
connection plate, is equipped with slits 64 and protrusions 66, in
order to correspond to the peripheral contour of the stock of heat
exchanger tubes 26. The protrusions 66 extend into furrows 154 (see
FIG. 6). Connection of the intermediate plate 140 to the wall 40
occurs via a gradation 80 of wall 40, which provides a stop and
seat for the intermediate plate 140, as in the tube plate 78 that
was described in conjunction with FIG. 2. The peripheral contour in
the intermediate plate 140 also has shoulders 74 to accommodate the
reinforcement plates 76 (FIG. 7). By providing an intermediate
plate 140, an additional weight and cost reduction is achieved.
[0048] FIG. 8 shows the end of a flat heat exchanger tube 26 with a
further modified internal insert 90, with the wave flanks 110
running between the broad sides 102 of the heat exchanger tube 26
having a bent contour making them also flexible in the direction
between the broad sides 102. Such heat exchanger tubes 26, shaped
and welded from a sheet strip, can be provided in the entire heat
exchanger. It is particularly apparent from this depiction that the
rows 134 of cutouts 120 and intermediate connectors 130 extend over
the entire width of internal insert 90 and heat exchanger tube 26,
which is the preferred design.
[0049] However, according to the present proposal, rows 134 are
also spoken of, if the cutouts 120 and intermediate connectors 130
are not situated in all wave flanks 110. The same applies for the
design of the rows 134 themselves. Moreover, while only straight
rows 134 are shown, zig-zag rows 134, for example, are equally
expedient and may be used within the scope of the present
invention.
[0050] FIGS. 9-14 illustration another embodiment incorporating the
present invention in which a line-like wall thinning 158 was made
in the flanks 110 of the corrugated internal inserts 90, which
serve as a rupture site 159 (see FIG. 11) which passes through all
intermediate connectors 130. It is drawn as a line in FIGS. 9-14,
which otherwise show different internal inserts 90 in partial views
and make it clear that the shape and size of the cutouts 120 and
intermediate connectors 130 are subject to no special provisions
and can be designed according to the application, in order to
achieve the desired advantages with respect to resistance to
alternating temperature loads.
[0051] As shown in FIG. 10, the cross-sectional shape of the
cutouts 120 and the size of the individual cross-sections from the
end of the internal insert 90 in the direction toward the center
can be varied. Particularly widely protruding collars 160 are also
shown in FIG. 10, which collars 160 have proven to be particularly
advantageous during the soldering process which, as is known,
occurs in a finely adjusted temperature range, in which the
materials are already in a "doughy" state. The collars 160 prevent
"falling" in the region of the connections caused by gravity in
this state.
[0052] FIGS. 15 and 16 show the use of flat heat exchanger tubes 26
in conjunction with an air-cooled charge air cooler. The charge air
cooler has a collecting tank 24 with a wall 40, with the ends 94 of
the heat exchanger tubes 26 extending into openings of a tube plate
78 and, for example, soldered there. The tube plate 78 represents
the connection plane 50. The type of indirect connection provided
in this example between wall 40 and heat exchanger tube 26 (via an
intermediate tube plate 78) is unimportant. The sometimes extremely
hot charge air flows through the heat exchanger tubes 26, and
cooling air flows through corrugated ribs 166 situated between
tubes 26. The connectors 150 between the openings in the tube plate
78 are provided with a cross-section contour (see, for example,
FIG. 6) in order to support the flexible behavior of the
alternating temperature loads, and internal inserts 90 are situated
in the tubes 26 (as illustrated by the cutout of two tubes 26 FIG.
16). The internal insert 90 has rows 134 of cutouts 120 and
intermediate connectors 130 which extend, at least a bit, in the
longitudinal direction of the internal insert 90. Two or three such
rows 134 may be sufficient to achieve the intended effects. The
heat exchanger tubes 26 of this practical example are designed as
welded flat tubes and have no elevations on their broad sides 102,
as an additional difference relative to the application as an
exhaust heat exchanger. In this application, the much larger
section of the internal insert 90, not provided with cutouts 120
and intermediate connectors 130, can be provided with indentations
or similar formations that increase turbulence (not shown). The
internal inserts 90, however, as is preferably the case in the
application as an exhaust heat exchanger, can also have fully
closed wave flanks 110 in the mentioned much larger section.
[0053] The use of the described features means that ruptures in the
connection heat exchangertube/tube plate occur much more rarely.
The individual parts of the heat exchanger consisting of metal are
prepared, according to known methods, as required, so that they can
be metallically connected in a soldering furnace.
[0054] Because the internal insert as described has at least one
row of cutouts with an intermediate connector (at least in the
connection region of the flat heat exchanger tubes with the wall of
the collecting tank) in order to compensate for alternating
temperature loads, the resistance of the heat exchanger according
to the invention to alternating temperature loads was significantly
increased in comparison with the previously mentioned prior art, as
demonstrated by evaluation of an extensive series of experiments.
The number of achieved temperature alternations was increased to
more than double, without the previous ruptures or leaks occurring.
Improvements to this extent were not expected and make it clear
that even apparently slight differences relative to the prior art
can lead to significant advantages.
[0055] Still other aspects, objects, and advantages of the present
invention can be obtained from a study of the specification, the
drawings, and the appended claims. It should be understood,
however, that the present invention could be used in alternate
forms where less than all of the objects and advantages of the
present invention and preferred embodiment as described above would
be obtained.
* * * * *