U.S. patent application number 11/284530 was filed with the patent office on 2006-06-22 for heat exchanger and method of manufacturing.
Invention is credited to Jens Nies, Frank Opferkuch.
Application Number | 20060131007 11/284530 |
Document ID | / |
Family ID | 34927499 |
Filed Date | 2006-06-22 |
United States Patent
Application |
20060131007 |
Kind Code |
A1 |
Nies; Jens ; et al. |
June 22, 2006 |
Heat exchanger and method of manufacturing
Abstract
A heat exchanger including at least one collecting tank for
input and output of a first heat transfer medium, a plurality of
plastic tubes receiving the first heat transfer medium from the at
least one collecting tank and outputting the first heat transfer
medium to the at least one collecting tank, and a plurality of
metal heat exchange elements between the tubes and in heat exchange
contact with the tubes and a second heat transfer medium. At least
some of the heat exchange elements are incorporated in the tube
walls, with wave crests and troughs embedded in furrows of the
walls. The heat exchanger is manufactured by heating the heat
exchange element to plasticize the tubes at least at the contact
sites between the tubes and the heat exchange elements, and then
producing intimate contact between the tube and the heat exchange
element.
Inventors: |
Nies; Jens; (Holzgerlinger,
DE) ; Opferkuch; Frank; (Unterensingen, DE) |
Correspondence
Address: |
WOOD, PHILLIPS, KATZ, CLARK & MORTIMER
500 W. MADISON STREET
SUITE 3800
CHICAGO
IL
60661
US
|
Family ID: |
34927499 |
Appl. No.: |
11/284530 |
Filed: |
November 21, 2005 |
Current U.S.
Class: |
165/152 ;
165/177; 165/905 |
Current CPC
Class: |
F28F 21/065 20130101;
B29C 66/114 20130101; B29C 66/112 20130101; F28F 2250/02 20130101;
B29C 66/53465 20130101; F28F 1/022 20130101; F28D 2001/0273
20130101; F28D 1/0366 20130101; F28F 21/062 20130101; B29K 2705/00
20130101; B29L 2031/18 20130101; F28D 1/05383 20130101; F28F 1/126
20130101; B29C 66/131 20130101; F28F 21/084 20130101; B29C 66/8322
20130101; B29C 66/7422 20130101; B29C 65/46 20130101 |
Class at
Publication: |
165/152 ;
165/177; 165/905 |
International
Class: |
F28D 1/02 20060101
F28D001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 24, 2004 |
EP |
04 027 827.7 |
Claims
1. A heat exchanger, comprising: at least one collecting tank for
input and output of a first heat transfer medium; a plurality of
plastic tubes receiving said first heat transfer medium from said
at least one collecting tank and outputting said first heat
transfer medium to said at least one collecting tank; and a
plurality of metal heat exchange elements between said tubes and in
heat exchange contact with said tubes and a second heat transfer
medium.
2. The heat exchanger of claim 1, wherein said tubes have walls,
and at least some of said heat exchange elements are incorporated
in said tube walls.
3. The heat exchanger of claim 2, wherein said corrugated ribs have
wave crests and wave troughs, and said crests and troughs are
embedded in said tube walls whereby the crests and troughs lie in
furrows of the walls.
4. The heat exchanger of claim 3, wherein said wave crests and wave
troughs have protrusions which penetrate into the tube walls.
5. The heat exchanger of claim 4, wherein said protrusions pass
through the tube walls.
6. The heat exchanger of claim 1, wherein said tubes are extruded
flat tubes.
7. The heat exchanger of claim 6, wherein said tubes are
multi-chamber tubes.
8. The heat exchanger of claim 1, wherein said heat exchange
elements are corrugated ribs.
9. The heat exchanger of claim 8, wherein said ribs are produced
from one of the group consisting of an aluminum sheet and a
non-ferrous heavy-metal sheet.
10. The heat exchanger of claim 1, wherein said heat exchange
elements are flat ribs having protruding fins with the ends of said
fins incorporated in walls of the tubes.
11. The heat exchanger of claim 1, further comprising metal
internal inserts in the plastic tubes.
12. A method of producing a heat exchanger according to claim 1
with said tubes and heat exchange elements assembled in a heat
exchanger block, comprising the steps of: heating the heat exchange
element to plasticize the tubes at least at the contact sites
between the tubes and the heat exchange elements; and producing
intimate contact between the tube and the heat exchange
element.
13. The method of claim 12, wherein said heating step is
accomplished by an electrical induction current.
14. The method of claim 12, wherein said heat exchange elements are
corrugated ribs with wave crests and wave troughs and, during said
heating step, heat input is concentrated on said wave crests and
wave troughs.
15. The method of claim 12, further comprising cooling within the
tubes during said heating step.
16. The method of claim 15, wherein said cooling is accomplished by
compressed air in said tubes.
Description
CROSS REFERENCE TO RELATED APPLICATION(S)
[0001] Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
[0003] Not applicable.
TECHNICAL FIELD
[0004] The present invention is directed toward heat exchangers,
and particularly toward heat exchangers having plastic
components.
BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEMS POSED BY THE
PRIOR ART
[0005] DE 33 02 150 A1 discloses one example of a heat exchanger
having flat metal tubes and flat metal ribs having the contour of
the openings corresponding to the flat tubes. One flat tube each is
inserted through each opening of a stack of ribs so that a heat
exchanger block is formed by a number of tubes that are passed
through a stack of ribs. The heat exchanger also has side parts
made of plastic and a bottom part viewed as a collecting tank,
which also consists of plastic. The soldering process often
required to produce heat exchangers is avoided by this structure,
thereby advantageously allowing the significant energy
requirements, related costs and environmental burdens of soldering
processes to be avoided. However, the contact between the flat
tubes and the heat exchanger elements is not particularly intensive
in this structure, and therefore heat exchange is inhibited. An
identical design of the heat exchangers with respect to the
described features can also be found in DE 32 02 901 C2 and DE 32
10 114 C2.
[0006] DE 37 28 303 A1 discloses a heat exchanger having round
tubes and heat exchange elements (flat or corrugated ribs) made of
plastic, which were produced in one piece with the tubes. This heat
exchanger can also be produced without soldering, but heat exchange
efficiency is not ideal. WO 00/43722 A1 also teaches round tubes
made of plastic, without heat exchange elements between the tubes,
where the tubes run in close wave-like rows to increase heat
transfer between the cooling air flowing around the tubes and the
charge air flowing in the tubes by deflecting the cooling air
several times. Heat exchange efficiency is not ideal with this
structure either.
[0007] A heat exchanger that can have either metal or plastic tubes
is described in EP 191 956 A1. The material to be used for the
other components of the heat exchanger, especially for the heat
exchange element, is not mentioned there, although it can be
concluded from the configuration shown in the figures that it was
produced from plastic. The heat exchanger has no collecting tanks
but the heat exchanger block is situated in a housing and is
traversed in cross-flow by the two heat exchange media. Its heat
exchange efficiency is also not ideal.
[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 at least one collecting tank for input and
output of a first heat transfer medium, a plurality of plastic
tubes receiving the first heat transfer medium from the at least
one collecting tank and outputting the first heat transfer medium
to the at least one collecting tank, and a plurality of metal heat
exchange elements between the tubes and in heat exchange contact
with the tubes and a second heat transfer medium.
[0010] In one form of this aspect of the present invention, the
tubes have walls, and at least some of the heat exchange elements
are incorporated in the tube walls. In a further form, the
corrugated ribs have wave crests and wave troughs, and the crests
and troughs are embedded in the tube walls whereby the crests and
troughs lie in furrows of the walls. In a still further form, the
wave crests and wave troughs have protrusions which penetrate into
the tube walls. In a yet further form, the protrusions pass through
the tube walls.
[0011] In another form of this aspect of the present invention, the
tubes are extruded flat tubes. In a further form, the tubes are
multi-chamber tubes.
[0012] In still another form of this aspect of the present
invention, the heat exchange elements are corrugated ribs. In a
still further form, the ribs are produced from one of the group
consisting of an aluminum sheet and a non-ferrous heavy-metal
sheet.
[0013] In yet another form of this aspect of the present invention,
the heat exchange elements are flat ribs having protruding fins
with the ends of the fins incorporated in walls of the tubes.
[0014] In still another form of this aspect of the present
invention, metal internal inserts are in the plastic tubes.
[0015] In another aspect of the present invention, a method of
producing a heat exchanger such as described above is provided,
with the tubes and heat exchange elements assembled in a heat
exchanger block, comprising the steps of (1) heating the heat
exchange element to plasticize the tubes at least at the contact
sites between the tubes and the heat exchange elements, and (2)
producing intimate contact between the tube and the heat exchange
element.
[0016] In one form of this aspect of the present invention, the
heating step is accomplished by an electrical induction
current.
[0017] In another form of this aspect of the present invention, the
heat exchange elements are corrugated ribs with wave crests and
wave troughs and, during the heating step, heat input is
concentrated on the wave crests and wave troughs.
[0018] In still another form of this aspect of the present
invention, cooling within the tubes is accomplished during the
heating step. In a further form, the cooling is accomplished by
compressed air in the tubes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a front view of a heat exchanger embodying the
present invention;
[0020] FIG. 2 is an enlarged cross-sectional view of a corner of
the heat exchanger of FIG. 1;
[0021] FIG. 3 is a view of the tube ends of the heat exchanger;
[0022] FIG. 4 is another cross-section through the FIG. 1 heat
exchanger, running through one of the ribs.
[0023] FIG. 5 is an enlarged cross-sectional view of one of the
tubes according to one embodiment of the present invention;
[0024] FIG. 6 is an illustration of the joining of a corrugated rib
and a flat tube according to the present invention;
[0025] FIG. 7 is a cross-sectional view of a wall of a flat tube
and an associated corrugated rib in another embodiment of the
present invention;
[0026] FIG. 8 is a cross-sectional view of a tube and associated
rib according to another embodiment of the present invention;
[0027] FIG. 9 is a top view of a curved heat exchange block
according to an embodiment of the present invention;
[0028] FIG. 10 is an exploded view of a tube and a heat exchanger
element having protrusions according to an embodiment of the
present invention;
[0029] FIG. 11 is a view from the side of FIG. 10 showing the heat
exchanger element and protrusion;
[0030] FIGS. 12 and 13 illustrate another embodiment of the present
invention with another heat exchanger element;
[0031] FIG. 14 is a schematic illustrating the production of a heat
exchanger core according to the present invention; and
[0032] FIG. 15 is a cross-sectional view of yet another flat tube
and heat exchanger element combination with which the present
invention may be used.
DETAILED DESCRIPTION OF THE INVENTION
[0033] Heat exchangers 20 variously embodying the present invention
are illustrated in the Figures. Such heat exchangers 20 can be
advantageously used, for example, in a vehicle as a radiator, a
charge air cooler or an oil cooler, but it should be understood
that heat exchangers incorporating the present invention may
advantageously be used in other applications as well
[0034] As is apparent from FIG. 1, the heat exchanger has a heat
exchanger block 22 assembled from flat tubes 26 and heat exchange
elements (corrugated ribs 28). The flat tubes 26 are a suitable,
for example, one with the designation PA 6.6 which has proven to be
particularly suitable in heat exchangers in the aforementioned area
of application. Extruded flat tubes are prescribed as the flat
tubes 26 of the illustrated example, with the corrugated ribs 28
produced from sheet aluminum (though brass or copper or nonferrous
heavy-metal sheets are other suitable alternatives) such as are
already known and available. It should be understood, however, that
the term "tube" according to the present invention may mean
essentially all forms and designs of lines in which a medium can
flow and exchange heat with a medium flowing outside of the line.
Moreover, it should also be understood that corrugated ribs in the
present context includes all wave-like heat exchange elements,
regardless of the design of the individual waves, wavelength, wave
height, etc. For example, so-called rectangular plates also could
be considered to be corrugated ribs for the purpose of this
application.
[0035] The heat exchanger of the illustrated embodiment has two
collecting tanks 30 and 32 arranged on opposite ends 36 of the flat
tubes 26. The collecting tanks 30, 32 as illustrated are inlet and
outlet collecting tanks, although it will be understood by those
skilled in the art that in some applications a single tank could
serve as both the inlet and outlet. In versions (not shown) with
only one collecting tank, a partition divides the collecting tank
into an inlet and outlet collecting tank part and, in such cases,
only one so-called deflection tank can be situated on the opposite
end 36 of flat tube 26 or the ends 36 of flat tubes 26 can be
closed, in which case the flat tubes 26 then advantageously have at
least one internal partition. If a deflecting tank is provided, the
partition in the tubes can be dispensed with, so that some tubes of
the heat exchanger block are allocated to the inlet collecting tank
part and other tubes to the outlet collecting tank part.
[0036] In accordance with the present invention, the collecting
tanks 30, 32 may also advantageously consist of plastic. The ends
36 of the flat tubes 26 may be inserted into openings of the
collecting tanks 30, 32 or into openings of tube bottoms that are
part of the collecting tanks 30, 32, with a suitable stable and
tight fastening therebetween provided by, for example, by welding
or gluing (FIG. 2). The heat exchanger 20 may also have side plates
38 on opposite sides lying against the outermost corrugated ribs
28, with the plate ends connected to the collecting tanks 30 and 32
such as is known in the art.
[0037] As clearly shown in FIGS. 2 and 5, part of the corrugated
ribs 28 are embedded or incorporated in the wall 40 of the flat
tubes 26. The wave crests 44 and the wave troughs 46 even pass
through the walls 40 of adjacent flat tubes 26, with the walls 40
perforated slit-like. It should be appreciated that, with this
practical example, the tightness of the connections of wave crest
44 or wave trough 46 to wall 40 should be carefully controlled
since a coolant is situated within the flat tubes 26 which must not
leak through the connections. If necessary, good heat-conducting
adhesives can also be used.
[0038] Cooling air freely flows through the corrugated ribs 28
perpendicular to the plane of the drawing in FIG. 1. Passage of the
corrugated ribs 28 through walls 40 can be present almost over the
entire depth of corrugated ribs 28 or flat tubes 26 in the
direction of cooling air flow, or protrusions 48 which penetrate
the wall 40 of flat tubes 26 can be formed on the wave crests 44
and wave troughs 46 of the corrugated ribs 28. Further, the front
and rear edges lying in the direction of the depth of corrugated
ribs 28 may be advantageously aligned in order to ensure better
sealing to the interior of flat tubes 26. FIGS. 10 and 11 show a
practical example with protrusions 48 on the wave crests 44 and
wave troughs 46.
[0039] In FIG. 5, arrows pointing from the bottom up in the
interior of flat tube 26 show the coolant flowing in direct contact
with the wave crests 44 and wave troughs 46 of the corrugated ribs
28 so that very good heat exchange efficiency is achieved. This
should direct contact with the metal particularly advantageous
given that the tubes 26 consist of plastic, which is generally
known to have lower heat conductivity than metal, whereby the
direct contact allows heat transfer to the metal ribs 28 without
any insulation effect from the plastic walls 40. The arrows in FIG.
5 also illustrate that flow of the coolant is disturbed by the
inward extending parts of the corrugated ribs 28, whereby heat
exchange efficiency is additionally influenced in a positive
way.
[0040] A heat exchanger of the described type is a distinct
progress relative to the prior art in almost any relation, both in
terms of cost-effective production and in terms of excellent heat
exchange efficiency. The heat exchanger also has a comparatively
limited weight and may be readily adapted to different applications
(i.e., the necessary design changes can be converted to a specific
product with relatively limited expense).
[0041] The flat tubes 26 according to the practical example in FIG.
3 are multi-chamber tubes produced, for example, by an extrusion
method. Two separation joints 56 in each flat tube 26 form three
chambers, with the wall thickness "s" (see FIG. 5) of the flat tube
26 advantageously lying in a range well below 1 mm. Any suitable
manufacturing methods for plastic tubes able to make the tubes with
such wall thicknesses, including methods able to make smaller wall
thicknesses than by extrusion, may be advantageously used in
producing the present invention. The wall thickness "s" of the
corrugated ribs 28 may advantageously lie in the range from one
tenth or even one-hundredth of a millimeter.
[0042] As illustrated in FIGS. 8 and 9, the flat tubes 26 may,
where desired, advantageously be formed with conical broad sides 60
and increasing wall thicknesses rather than parallel sides. The use
of such flat tubes 26 permits the heat exchanger to be curved with
a contour, rather than a flat heat exchanger block 22.
[0043] FIG. 8 also illustrates another concept, wherein the
penetration depth T of the corrugated ribs 28 into the wall 40 of
the flat tube 26 is correspondingly deeper with increasing wall
thickness "s" of the flat tube 26. Of course, a flat heat exchanger
block 22 can also be produced in this manner, where the intended
thermodynamic effects can be achieved by the fact that the channels
between the flat tubes 26 through which the cooling air flows
narrow or widen in the direction of cooling air flow. (Narrowing or
widening of the channel can be recognized in FIG. 8 in that the
"free" height of the corrugated rib 28 on the left side is less
than on the right side. The penetration depth T on the left is
therefore greater than on the right. Moreover, it will be
appreciated that a second identically arranged flat tube 26 in the
upper end FIG. 8 would result in a channel which is narrower on the
left than on the right.) The flow rate of the cooling air is
therefore altered and, as desired, affects the pressure loss in the
cooling air.
[0044] Cuts 64 are schematically shown in FIGS. 7 and 8 in the
flanks 66 of the corrugated ribs 28 and also in other heat exchange
elements 28 in order to ensure increased turbulence in the cooling
air and therefore more efficient heat exchange. According to the
practical example of FIG. 7, no perforations are present through
the wall 40 of the flat tube 26, although the wall thickness is
advantageously and significantly reduced to improve contact. A wave
crest 44 or wave trough 46 is arranged in a furrow 68 formed in the
tube walls.
[0045] FIGS. 12 and 13 illustrate other heat exchange elements 28
having a flat surface 70 from which fins 72 point in the opposite
direction protrude from surface at tight spacing. FIG. 12 is a
cross-sectional view of the heat exchanger block 22 showing the
narrow sides of only two flat tubes 26. FIG. 13 shows the section
through the top of FIG. 12 from which the longitudinal direction of
the flat tubes 26 is consequently seen. Both Figures illustrate
only features necessary to understand the basic structure disclosed
therein.
[0046] FIG. 15 shows a practical example which is similar to FIG.
13 in terms of the view, wherein each flat tube 26 is formed from
two plates 76 with two rods 78 extending along the longitudinal
edges of the plates 76. In this embodiment, the corrugated rib 28
penetrates the platex 76, and the flank of corrugated rib 28 is
provided with cuts 64. The heat exchanger of FIG. 15 also includes
a metal insert 80 (made of, e.g., aluminum sheet) within each flat
tubes 26. The insert 80 can also be incorporated in the plates 76
of the flat tubes 26, in this case from the inside. Such designs
are particularly advantageous for air-cooled charge air coolers. It
should be appreciated that while the internal inserts 80 are shown
here in connection with flat tubes 26 formed from plates 76 and
rods 78, they are not restrict to use with such tubes 26. Further,
it should be appreciated that the depiction in FIG. 15 is purely
schematic.
[0047] In conjunction with the Figures already explained, FIG. 14
shows a more detailed view of an advantageous production method in
which the plastic flat tubes 26 and heat exchange elements 28 are
combined into a heat exchanger block 22. The heat exchanger block
22 is shown roughly in the center of FIG. 14, with the metal heat
transfer elements 28 heated by an induction current as indicated by
the bundle of arrows 84. The walls 40 of the plastic flat tubes 26
are plasticized by heat input at least on the contact sites between
the wall 40 and the heat exchange elements 28 whereby they are
temporarily converted to a slightly doughy state. This process of
plastification can be controlled, for example, by simultaneously
supplying compressed cooling air through flat tubes 26 while
heating the heat exchange elements 28. During production, a
corresponding ratio between cooling air inside the tubes 26 and
heat input into the outer corrugated ribs 28 may be advantageously
maintained or adjusted in order to optimize the contact
therebetween. In addition, a proportioned force is deliberately
applied in the direction of the two arrows 86 against the left and
right of heat exchanger block 22 whereby intimate contact is
established between the tubes 26 and the heat exchange elements 28.
The connections between the flat tubes 26 and the heat exchange
elements 28 after completion of the process and a cooling time,
appear approximately as shown in FIG. 7 and described previously.
No perforations on walls 40 are present, and consequently there are
no problems with respect to sealing, although it should be
appreciated that it would be within the scope of the present
invention to otherwise form the connections such as previously
described, including the connection of FIG. 5 in which the heat
exchange elements 28 pass through wall 40 and reach the interior of
flat tubes 26, and the connection of FIGS. 10 and 11 in which
protrusions 48 deeply penetrate walls 40 to ensure intense
connection.
[0048] It should also be understood that the production method can
initially produce individual subblocks of the subsequent heat
exchanger block 22 (e.g., a heat exchange element 28 and one or two
tubes 26), with the heat exchange element or elements 28 heated and
joined to the tube or tubes during production of the subblocks.
Matching subblocks can then, as described, be assembled (also by
heating) into an entire heat exchanger block 22 at the seams of the
subblocks of the heat exchange elements 28. Moreover, the heat
exchanger block 22 can also be produced by assembling tubes 26 and
heat exchange elements 28 in alternation individually. In this
case, each individual-added heat exchange element 28 is heated and
joined to one or two tubes 26. Such production may be achieved
without having to use a soldering method to produce the heat
exchanger.
[0049] 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.
* * * * *