U.S. patent application number 10/885961 was filed with the patent office on 2005-01-27 for heat exchanger.
Invention is credited to Brost, Viktor, Lamich, Berhnhard.
Application Number | 20050016717 10/885961 |
Document ID | / |
Family ID | 33482996 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050016717 |
Kind Code |
A1 |
Lamich, Berhnhard ; et
al. |
January 27, 2005 |
Heat exchanger
Abstract
An improved heat exchanger includes an integral side piece/end
cap structure for closing the ends of tanks and providing a side
piece for each side of the heat exchanger and includes connecting
strands between an end cap section and a side piece section that
are weak, allowing the breakage thereof prior to excessive thermal
stresses being placed on tube to the header joints. Also disclosed
is the use of clips on end cap section and/or tank ends together
with a tab on the end cap section which may be used to self-fixture
of the components during assembly.
Inventors: |
Lamich, Berhnhard;
(Esslingen, DE) ; Brost, Viktor; (Aichtal,
DE) |
Correspondence
Address: |
WOOD, PHILLIPS, KATZ, CLARK & MORTIMER
500 W. MADISON STREET
SUITE 3800
CHICAGO
IL
60661
US
|
Family ID: |
33482996 |
Appl. No.: |
10/885961 |
Filed: |
July 7, 2004 |
Current U.S.
Class: |
165/149 ;
165/153 |
Current CPC
Class: |
F28F 2265/26 20130101;
F28F 9/001 20130101; F28F 9/0202 20130101; F28F 2220/00
20130101 |
Class at
Publication: |
165/149 ;
165/153 |
International
Class: |
F28D 001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 22, 2003 |
DE |
DE 103 33 150.6 |
Claims
What is claimed is:
1. A heat exchanger comprising: a pair of parallel headers each
having spaced tube slots aligned with tube slots in the other
header; tubes extending between aligned ones of the tube slots in
said headers; fins extending between the tubes; side pieces on
opposed sides of the heat exchanger embracing said fins thereat and
extending substantially between corresponding ends of the headers;
a pair of channel-like tanks, one for each header, fitted to the
corresponding header oppositely of the tubes; and end caps having
bent edges embracing and sealingly closing opposite ends of each
said tank, said end caps being integral extensions of each end of
each side piece to form end cap/side pieces and characterized by a
reduction in cross section of each end cap/side piece adjacent each
end of each header of at least about 50%, each defined by at least
one cutout thereat.
2. A heat exchanger comprising: a pair of parallel headers each
having spaced tube slots aligned with tube slots in the other
header; tubes extending between aligned ones of the tube slots in
said headers; fins extending between the tubes; side pieces on
opposed sides of the heat exchanger embracing said fins thereat and
extending substantially between corresponding ends of the headers;
a pair of channel-like tanks, one for each header, fitted to the
corresponding header oppositely of the tubes; and end caps having
bent edges embracing and sealingly closing opposite ends of each
said tank, said end caps being integral extensions of each end of
each side piece to form end cap/side pieces and characterized by a
reduction in cross section of each end cap/side piece adjacent each
end of each header of at least about 50%, each defined by at least
one cutout thereat; and fasteners for securing said end caps to
said tank ends during assembly of the heat exchanger.
3. The heat exchanger of claim 2 wherein each said reduction is at
least about 80% of said cross section and said end caps and side
pieces remain integral about said cutout(s) through the retention
of a connecting strand or a small number of connecting strands
extending across said cutout(s) from the side piece to the integral
end caps on each end of each side piece.
4. The heat exchanger of claim 3 wherein said heat exchanger is
formed of aluminum and is assembled by brazing, said connecting
strands being sized to be readily severed if necessary.
5. The heat exchanger of claim 2 wherein said fasteners include
resilient U-shaped clips on said end cap bent edge or said ends of
said tanks.
6. The heat exchanger of claim 2 wherein said fasteners include a
tab on each end cap bendable to overly and engage an adjacent end
of said tank.
7. The heat exchanger of claim 5 wherein said U-shaped clips each
includes a sloped extremity on at least one of the legs thereon to
serve as a pilot surface for receipt of a corresponding end of said
tanks or a corresponding bent edge of said end caps.
8. The heat exchanger of claim 2 wherein said cutout(s) defines a
central connecting strand extending between each side piece and the
associated end caps.
9. The heat exchanger of claim 2 wherein said cutout(s) defines two
spaced off center connecting strands extending between each side
piece and the associated end caps.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a heat exchanger, and more
particularly, to a heat exchanger whose components are assembled to
one another by soldering or brazing, for example, aluminum heat
exchangers.
BACKGROUND OF THE INVENTION
[0002] Heat exchangers for vehicles as, for example, radiators or
charge air coolers, conventionally include a plurality of parallel,
spaced, flat tubes that extend between header plates with tube
slots which sealingly receive the ends of the flat tubes.
Serpentine fins are disposed between adjacent ones of the tubes and
collecting tanks are assembled in sealed relation to header plates
on sides thereof opposite the tubes. As is typical with the heat
exchangers utilizing the serpentine fins, to facilitate assembly,
side pieces are located along each side of the heat exchanger core
and extend between corresponding ends of the two headers to
sandwich a serpentine fin against an endmost tube in the core.
Frequently, the heat exchangers are made from aluminum in which
appropriate part surfaces are clad with a braze alloy to allow the
components to be assembled together by a brazing process. It is
likewise possible to make copper or copper/brass heat exchangers
using solder in lieu of a braze alloy.
[0003] It has been proposed in German patent application No. DE 102
37 769.3 to make the tanks of such heat exchangers out of
channel-like material. Closure caps are fitted to the ends of the
tanks and the same may be formed separately or integrally with the
side pieces. For example, one side piece may have two closure caps
formed thereon, one on each end of the side piece, to be fitted to
the tank end at the corresponding end of each header plate.
[0004] A typical problem that occurs in the production of such heat
exchangers is that the heat exchanger must be assembled from its
individual parts in preparation for brazing or soldering. This
means constituents must be temporarily fastened until the joining
process is completed. Currently, various fixtures or jigs are used
for the purpose and clamp the heat exchanger in assembled relation.
The heat exchanger remains clamped until the soldering or brazing
process is completed.
[0005] In order to minimize or eliminate the need for such
fixtures, there have been proposed various expedients whereby parts
of the heat exchanger itself are provided with integral fastening
devices which eliminate one or more fixtures or jigs. By way of
example, reference is made to U.S. Pat. No. 6,131,286 dated Oct.
17, 2000 which discloses a tab and slit instruction for temporarily
holding two metal pieces together during a joining process. This
type of pre-assembly fastening is problematical in the fabrication
of heat exchangers because of the required slit. In heat
exchangers, the slit and the protrusion must be joined absolutely
tightly or else the heat exchanger will leak.
[0006] In addition, so-called "thermal cycling" that occurs during
the operation of heat exchangers, often leads to breaks. Thermal
cycling occurs, for example, in a vehicle when the engine is
operating when the heat exchanger runs at relatively high
temperature and when the engine is turned off, the heat exchanger
cools to ambient temperature. Temperature gradients also lead to
the same problem. Even in operation with the heat-exchange fluids
at constant pressures, the side pieces in heat exchangers and the
endmost tubes in the core tend to run cooler than those in the
center of the core.
[0007] In either event, thermal stresses arise and typically are
concentrated at the tube to header joints. Of course, if the
thermal stress leads to cracks at tube to header joints, the heat
exchanger begins to leak and frequently will require some sort of
repair which can be expensive and which can lead to extensive down
time for the apparatus with which the heat exchanger is used.
[0008] The present invention is directed to solving one or more of
the above problems.
SUMMARY OF THE INVENTION
[0009] It is the principal object of the invention to provide a new
and improved heat exchanger. More specifically, one object of the
invention is to provide a heat exchanger that may be readily
manufactured with little or no use of jigs or fixtures in the
pre-assembly process.
[0010] It is also a principal object of the invention to provide a
heat exchanger that is less susceptible to failure or leakage due
to thermal cycling or thermal gradients.
[0011] An exemplary embodiment of the invention achieves the
foregoing objects in heat exchangers that include a pair of
parallel headers, each having spaced tube slots aligned with tube
slots in the other header. Tubes extend between aligned ones of the
tube slots in the headers and fins extend between the tubes. Side
pieces on opposed sides of the heat exchanger embrace the fins
thereat and extend substantially between the corresponding ends of
the headers. A pair of channel-tanks, one for each header, is
fitted to the corresponding header oppositely of the tubes and end
caps having bent edges embracingly and sealingly closing opposite
ends of each tank are provided. The end caps are integral
extensions of each end of each side piece to form end cap/side
pieces. The heat exchanger is characterized by a reduction in cross
section of each end cap/side piece adjacent each end of each header
of at least about 50%. Each such reduction is defined by at least
one cutout adjacent each end of each header.
[0012] In a preferred embodiment, fasteners are provided for
securing the end caps to the tank ends during assembly of the heat
exchanger.
[0013] In a highly preferred embodiment, each of the cross section
reductions is at least about 80% of the cross section, and the end
caps and side pieces remain integral about the cutout or cutouts
through the retention of a connecting strand or a small number of
connecting strands extending across the cutout(s) from the side
piece to the integral end cap at each end of each side piece.
[0014] In one embodiment, the heat exchanger is formed of aluminum
and is assembled by brazing. The connecting strand or strands are
sized to be readily severed if necessary.
[0015] In a preferred embodiment, the fasteners include resilient,
U-shaped clips on the end cap bent edge or on the ends of the
tanks. Preferably, the clips are integrally formed of projections
on the components.
[0016] In a preferred embodiment, the fasteners also include a tab
on each end cap which is bendable to overlie an adjacent end of the
tank.
[0017] In one embodiment, the U-shaped clips each include a sloped
extremity on at least one of the legs thereon to serve as a pilot
surface for receipt of a corresponding end of the tank or a
corresponding bent edge of the end caps.
[0018] In one embodiment, the cutout(s) defines a central
connecting strand extending between each side piece and the
associated end cap, while in another embodiment, the cutout(s)
defines two spaced, off-center connecting strands extending between
each side piece and the associated end caps.
[0019] Other objects and advantages will become apparent from the
following specification taken in connection with the accompanying
drawings.
DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a fragmentary, perspective view of a side piece
for a heat exchanger made according to the invention;
[0021] FIG. 2 is a view similar to FIG. 1, but of a modified
embodiment;
[0022] FIG. 3 is similar to FIGS. 1 and 2, but illustrates a third
embodiment;
[0023] FIG. 4 is similar to FIGS. 1-3, inclusive, but illustrates a
fourth embodiment;
[0024] FIG. 5 is an enlarged, fragmentary view of one corner of a
heat exchanger;
[0025] FIG. 6 is a side elevation taken from the left of FIG.
5;
[0026] FIG. 7 is a fragmentary sectional view taken approximately
along the line 7-7 in FIG. 5;
[0027] FIG. 8 is a sectional view taken approximately along the
line 8-8 in FIG. 5;
[0028] FIG. 9 is a vertical section of the structure shown in FIG.
5;
[0029] FIG. 10 is an exploded view of the structure of FIG. 5;
[0030] FIG. 11 is a view similar to FIG. 10 but of a modified
embodiment of the invention;
[0031] FIG. 12 is a fragmentary, elevational view of a corner of a
heat exchanger made according to the invention;
[0032] FIG. 13 is a sectional view taken approximately along the
line 13-13 in FIG. 12; and
[0033] FIG. 14 is a sectional view taken approximately along the
line 14-14 in FIG. 12.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] As alluded to previously, the heat exchanger of the present
invention is ideally suited for vehicular use as, for example, a
vehicular radiator or charge air cooler. However, no limitation to
vehicular use, or to a radiator, or charge air cooler is intended
because those skilled in the art will recognize that the heat
exchanger of the invention may be used in a variety of environments
and for a variety of purposes. For example, the same could be
utilized in a heating system for a building, or the like. In any
event, no limitation to a particular environment of use or to a
particular use is intended except insofar as expressly stated in
the appended claims.
[0035] With the foregoing in mind, several embodiments of the
invention will now be described.
[0036] Turning first to FIGS. 8, 9, and 10, a typical heat
exchanger embodying the invention is shown fragmentarily. The same
includes two, spaced, parallel header plates 20 (only one of which
is shown) having upturned side edges 22 along its length. Elongated
tube slots 24 extend transversely to the length of each header
plate 20 from end to end thereof, and in turn receive the ends 26
of a plurality of flattened tubes 28 which extend between
corresponding tube slots 24 in the two headers.
[0037] An open-ended, open-bottomed channel-like tank, generally
designated 30, includes a base 32 with depending sides 34. The
sides 34 extend about the remote surfaces of the flanges 22 as well
as about the bent edge 36 of an end cap part 38 of a combination
side piece/end cap construction, generally designated 40. One or
more ports 42 will be located in the tank, typically in one of the
sides 34, for connection into the system with which the heat
exchanger is used.
[0038] As seen in FIGS. 9 and 10, the side piece/end cap assembly
40 includes an end piece section 44 in addition to the end cap
section 38. As perhaps best viewed in FIG. 9, the side piece
section 44 sandwiches a serpentine fin 46 against the endmost one
of the tubes 28. Typically, this structure will be provided on both
sides of the case. Additional serpentine fins 46 extend between
adjacent ones of the tubes 28 as well.
[0039] The foregoing description basically describes only a single
quadrant of a typical heat exchanger. Those skilled in the art will
recognize that a complete heat exchanger will include two of the
header plates 20 that are spaced in parallel with the tubes 28
running between the two header plates 20 as mentioned previously.
It will also include two of the tanks 30, one for each header
plate, and two of the side piece/end caps 40, one on each side of
the heat exchanger for sandwiching one of the fins 46 against the
endmost tube 28 on each side of the heat exchanger. Further, as
there will be two of the tanks 30, one assembled to each of the
header plates 20, there will be a total of four of the end cap
sections 38, one for each end of each of the two tanks 30.
[0040] In the usual case, all of the components will be made of
aluminum and, where required, provided with braze clad material,
i.e., an aluminum brazing alloy having a melting point somewhat
less than the melting point of the aluminum of which the components
are formed. In some cases, the braze cladding will be on only one
side of the component, while in other cases, it may be on both
sides of the component. In some cases, a component may not be braze
clad at all. By way of example, the tank 30 must be joined to the
end caps 38 as well as to the header plate flanges 22. If braze
cladding is located on the remote surfaces of the two flanges 22,
that is, the two that face away from each other, as well as on the
innermost side of the side piece/end cap 40, then the tank 30 may
be free of braze cladding because braze cladding will always be
present at the interfaces of the header plate flanges 22 and the
facing surface of the bent edge 36 of the end cap piece 38. In
addition, this will results in braze cladding being located on the
inner side of the side piece section of the end cap/side piece
structure 40 for bonding to the adjacent serpentine fin 46.
[0041] Turning now to FIGS. 1-4, four different forms of the end
cap/side piece assembly 40 will be described. In each case, each
side piece section 44 is formed integrally with two end cap
sections 38, with there being one end cap section 38 at each end of
the side piece section 44. Two sections 38 and 44 are separated by
one or more cutouts 50. In the embodiment of FIG. 1, cutouts 50 are
separated by a single connecting strand 52 which is located
centrally of the side piece/end cap assembly 40. In contrast,
cutouts 54 are arranged to define two, off-center connecting
strands 56 in the embodiment of FIG. 2.
[0042] FIG. 3 includes non-centered, multiple connecting strands 56
separated by cutouts 54 like the embodiment of FIG. 2 while the
embodiment of FIG. 4 includes a single, central connecting strand
52 and cutouts 50 as in the embodiment of FIG. 1.
[0043] In all cases, the side piece/end cap structures 40 are
integrally formed, that is, formed of a single piece of metal as by
stamping. The side piece sections 44 include flanges 60 that are
directed toward the endmost tube on the corresponding side of the
core and serve to confine the serpentine fin 46 that is sandwiched
against the endmost tube 28 by the side piece section 44 to aid in
assembly.
[0044] The embodiments of FIGS. 1 and 2 have identical end cap
sections 38. As mentioned previously, each end cap section 38 is
surrounded on three sides by a bent edge 36 about which one end of
a tank 30 is abutted to be sealingly bonded thereto. As seen in
FIGS. 1 and 2, integral, U-shaped clips 62 extend from the bent
edge 36 away from the tank (see also FIG. 8) with an outer leg 64
directed back toward the tank to resiliently clip on the end of the
tank. This serves to fasten the tank 30 to the end cap section 38
during brazing or soldering.
[0045] To facilitate fitting of the end of the tank 30 into the
clips 62, a sloped or slanted surface extension 66 extends away
from the end cap section 38 and is located on one side of the leg
64 to serve as a pilot to guide the lower end of a corresponding
side 34 of the tank 30 into the proper location and retain it by
the resilience of the material of which the clip 62 is made.
[0046] Each of the embodiments of FIGS. 1 and 2 also includes, on
the part 70 of the bent edge 36 remote from the side piece section
44 adjacent the part 70 of the bent side 36 a tab 72 which can be
bent and deformed over the wall 32 of the tank as best seen in FIG.
6. The tab 72 thus serves to hold the wall 32 in firm engagement
with the surface 70 during the brazing process to assure a
leak-free joint.
[0047] An embodiment of the invention utilizing the side piece/end
cap assemblies 40 shown in FIGS. 3 and 4 is illustrated in FIGS.
11-14. In this case, U-shaped spring clips 80 are integrally formed
on each end 82 of each tank 39, and specifically the sidewalls 34
thereof. As seen in FIG. 13, each of the U-shaped clips 80 includes
an outwardly flared or sloped surface for the clips 80 to allow
them to be fitted to outward projections on both sides of each end
cap section 38. That is, the flared sections 84 serve the same
purpose, in the embodiment of FIGS. 11-14 as the slope surfaces 66
of the clips 64 in the earlier illustrated embodiments using the
assemblies 40 of FIGS. 1 and 2.
[0048] The tab 72 is retained in the embodiment of FIGS. 10-14.
[0049] It is to be particularly noted that connecting strands 52,
56, and the various embodiments typically may be such that there is
a slight offset of the end cap section 38 from the side piece
section 44. As can be seen, for example, in FIGS. 5 and 9, it is
not unusual for the side piece section 44 to be located outwardly
of the end of the header adjacent thereto, and the offset
accommodates so locating the various components.
[0050] Importantly, the cutouts 50, 54 provide a weak spot at the
point whereat the side piece sections 44 would be connected
directly to the header 20 or connected via the connection to the
end cap section 38 and ultimately to the header 20 through the tank
30. It is this area whereat substantial thermal stress can exist
and is transmitted to the tube to header joints. Because the
connecting strands are relatively thin, as can be seen in the
drawings, they may readily fracture to relieve thermal stresses as
required. To achieve the desired relief in such circumstances, it
is highly desirable that the cross-sectional area of the piece of
metal of which each assembly 40 is formed be reduced by at least
50% at the cutouts 50 or 54. Preferably, the cross section
reduction is at least about 80%. The side of the reduction is
measured in a plane transverse to the length of each side piece/end
cap assembly.
[0051] Moreover, ideally, the connecting strands 52, 56 are sized
so that they may easily be intentionally severed if desired,
following brazing or soldering. In fact, it is only necessary that
the connecting strands 52, 56 be of sufficient cross-sectional area
as to provide some support for the end cap sections on the side
piece section 44 during pre-assembly using the clips 62, 80 and the
tab 72 during pre-assembly prior to brazing or soldering. Thus, it
will be seen that the invention provides a heat exchanger that
eliminates or minimizes thermal stresses at two of the header
joints that may cause failure due to thermal cycling and/or thermal
gradients. Furthermore, unique use of the clips and tabs eliminates
the need for special fixtures or jigs to hold the components making
up the heat exchanger in assembled relation prior to soldering or
brazing, thereby minimizing the cost of fixturing during
assembly.
* * * * *