U.S. patent application number 12/090761 was filed with the patent office on 2008-10-16 for heat exchanger.
This patent application is currently assigned to BEHR GmbH & Co. KG. Invention is credited to Klaus Irmler, Ulrich Maucher, Jens Ruckwied.
Application Number | 20080251242 12/090761 |
Document ID | / |
Family ID | 37653163 |
Filed Date | 2008-10-16 |
United States Patent
Application |
20080251242 |
Kind Code |
A1 |
Irmler; Klaus ; et
al. |
October 16, 2008 |
Heat Exchanger
Abstract
The invention relates to a heat exchanger, especially for
cooling exhaust gases. Said heat exchanger comprises at least one
first flow channel (2) of a fist medium, especially a gas, at least
one second flow channel (3) of an at least second medium especially
a cooling medium, at least one first disk (4), at least one second
disk (5), the first disk and the second disk being interconnected
and defining the first flow channel of the first medium, at least
one housing element (6), especially a first housing element (7) and
a second housing element (8) defining, together with the first disk
and the second disk, the second flow channel of the second medium,
wherein the first housing element can be cooled by the second
medium.
Inventors: |
Irmler; Klaus; (Ammerbuch,
DE) ; Maucher; Ulrich; (Korntal-Munchingen, DE)
; Ruckwied; Jens; (Stuttgart, DE) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
BEHR GmbH & Co. KG
|
Family ID: |
37653163 |
Appl. No.: |
12/090761 |
Filed: |
October 13, 2006 |
PCT Filed: |
October 13, 2006 |
PCT NO: |
PCT/EP2006/009924 |
371 Date: |
April 18, 2008 |
Current U.S.
Class: |
165/164 |
Current CPC
Class: |
F02M 26/32 20160201;
F28D 9/0043 20130101; F28D 21/0003 20130101; F28F 21/065 20130101;
F02M 26/31 20160201; F28F 9/26 20130101; F28F 9/001 20130101; F02M
26/30 20160201; F28D 9/0093 20130101; F28F 2250/104 20130101 |
Class at
Publication: |
165/164 |
International
Class: |
F28D 7/00 20060101
F28D007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2005 |
DE |
10 2005 050 686.0 |
Mar 24, 2006 |
DE |
10 2006 014 191.1 |
Claims
1. A heat exchanger, especially for cooling exhaust gases,
comprising at least one first flow channel of a first medium,
especially a gas, at least one second flow channel of an at least
second medium, especially a cooling medium, at least one first
disk, at least one second disk, the first disk and the second disk
being interconnected and forming the first flow channel of the
first medium, with at least one housing element, especially a first
housing element and a second housing element forming, together with
the first disk and with the second disk, the second flow channel of
the second medium, wherein the first housing element can be cooled
by the second medium.
2. The heat exchanger as claimed in claim 1, wherein the second
medium, especially cooling medium, is able to flow around
substantially all of the first housing element.
3. The heat exchanger as claimed in claim 1 wherein the temperature
of the first medium, especially of the exhaust gas of an internal
combustion engine, prior to entering the heat exchanger is higher
than the temperature of the second medium, especially of the
cooling medium, prior to entering the heat exchanger.
4. The heat exchanger as claimed in claim 1, wherein the first
housing element is made of a first material, especially aluminum or
plastics material, and the second housing element is made of
another second material, especially steel.
5. The heat exchanger as claimed in claim 1, wherein the second
housing element has at least one housing opening, especially a
first housing opening for an entry of the first medium into the
first flow channel, especially a second housing opening for an exit
of the first medium from the first flow channel, especially a third
housing opening for an entry of the second medium into the second
flow channel and especially a fourth housing opening for an exit of
the first medium from the second flow channel.
6. The heat exchanger as claimed in claim 1, wherein first housing
element and the second housing element can be opened in at least
one stacking direction S of the first disks and the second
disks.
7. The heat exchanger as claimed in claim 1, wherein the first
housing element and the second housing element are interconnected
with a material fit, especially by soldering, welding, bonding,
etc., and/or interconnected with a form fit, especially by
screwing, clipping, or by deformation such as folding, crimping,
bordering, etc.
8. The heat exchanger as claimed in claim 1, wherein the first
housing element and the second housing element are sealed relative
to one another using a sealing element, especially an O-ring, a
square ring, a film seal, etc.
9. The heat exchanger as claimed in claim 1, wherein the first disk
and/or the second disk have projections, especially
turbulence-generating elements.
10. The heat exchanger as claimed in claim 1, wherein the first
disks and/or the second disks each have at disk ends at least one
cup.
11. The heat exchanger as claimed in claim 10, wherein the cups
each have at least one cup opening, especially for the passage of
the first cooling medium.
12. The heat exchanger as claimed in claim 1, wherein a respective
first disk and a respective second disk form a pair of disks and
are interconnected with a material fit, especially by soldering,
welding, bonding, etc.
13. The heat exchanger as claimed in claim 12, wherein a plurality
of pairs of disks can be stacked on one another and are
interconnected at cup opening edges with a material fit, especially
by soldering, welding, bonding, etc.
14. The heat exchanger as claimed in claim 12, wherein the pairs of
disks form the first flow channels for the first medium, especially
for exhaust gas to be cooled.
15. The heat exchanger as claimed in claim 12, wherein adjacent
pairs of disks are arranged set apart from one another, thus
forming the second flow channels of the second medium, especially
cooling medium.
16. The heat exchanger as claimed in claim 1, wherein the second
flow channels of the second medium, especially cooling medium, are
formed at least between the first housing element and a disk pair
edge surface.
17. The heat exchanger as claimed in claim 1, wherein third flow
channels of a third medium are formed next to the second flow
channels.
18. The heat exchanger as claimed in claim 17, wherein the third
flow channels of the third medium are formed between the first
housing element and the disk pair edge surfaces.
19. The heat exchanger as claimed in claim 17, wherein the third
flow channels are separated from the second flow channels,
especially by at least one partition element.
20. The heat exchanger as claimed in claim 17, wherein the second
medium, especially cooling medium, of a high-temperature cooling
circuit is able to flow through the second flow channels and a
third medium, especially cooling medium, of a low-temperature
cooling circuit is able to flow through the third flow
channels.
21. The heat exchanger as claimed in claim 1, wherein the first
housing element is an integral part of at least one other
component, especially a water jacket, a cylinder head of an
internal combustion engine, a water tank of a coolant cooler,
etc.
22. The heat exchanger as claimed in claim 1 wherein the heat
exchanger has a second housing element but no first housing
element.
Description
[0001] The present invention relates to heat exchangers, especially
for cooling exhaust gases, and to a modular heat exchanger
system.
[0002] Current diesel engines are normally equipped with exhaust
gas recirculation coolers in order to satisfy the increasingly
stringent demands placed on exhaust gas purification. The cooling
of the exhaust gas and resupplying of the cooled exhaust gas
reduces the combustion temperature and leads to decreased NOX
emissions.
[0003] DE 102 30 852 A1 discloses a heat exchanger with a first
collecting vessel and with a second collecting vessel for a first
medium, the two collecting vessels each having a first media
connection for the first medium and being interconnected in a
communicating manner via at least one heat exchanger element, and
with a housing which accommodates the heat exchanger element,
guides a second medium in the inside and has second media
connections for the second medium. The housing accommodates, in the
interior thereof, at least one collecting vessel, preferably both
collecting vessels, so that they are located, at least in part, at
a distance from the housing inner wall at least in certain
regions.
[0004] DE 100 61 949 A1 further discloses a heat exchanger having a
core region for carrying out an exchange of heat between a first
fluid and a second fluid, the core region having a large number of
tubes which form in the inside first passageways through which the
first fluid flows, the tubes being arranged to form a plurality of
spaces between adjacent tubes through which the second medium
flows, and a large number of ribs which are each arranged in each
space between adjacent tubes to divide each space into a plurality
of space parts which are interconnected via openings provided in
each rib; and a core housing in which the core region is
accommodated and which forms a second passageway having the
plurality of spaces, the two ends of each tube being separated from
the inner wall surface of the core housing in the width direction
at right angles to the longitudinal direction of the tubes, so as
to form predetermined free spaces from the inner wall surface of
the core housing, and the predetermined free spaces being provided
in such a way that they are interconnected along the entire surface
region of the tubes in the lamination direction of the tube.
[0005] Exhaust gas coolers are generally laser-welded or soldered
based on Ni and have ribs on the gas side. In this case, ribs are
normally encased in tubes and subsequently soldered in a housing.
Other known designs provide for disks to be soldered to one
another.
[0006] Most applications generally provide for gas to flow axially
through a set of disks, the coolant being supplied or removed from
above via the cover plate. Nevertheless, this design has the
problem that the housing can generally become very warm, as the
housing is not cooled.
[0007] Starting herefrom, the invention is based on the object of
improving a heat exchanger, especially for cooling exhaust gases,
and a modular heat exchanger system.
[0008] According to the invention, the object is achieved by a heat
exchanger as claimed in claim 1, especially for cooling exhaust
gases, with at least one first flow channel of a first medium,
especially a gas, with at least one second flow channel of an at
least second medium, especially a cooling medium, with at least one
first disk, with at least one second disk, the first disk and the
second disk being interconnected and forming the first flow channel
of the first medium, with at least one housing element, especially
a first housing element and a second housing element forming,
together with the first disk and with the second disk, the second
flow channel of the second medium, wherein the first housing
element can be cooled by the second medium.
[0009] The first flow channel leads via entry openings in the [ . .
. ] for the first medium, which [ . . . ] especially hot exhaust
gas having a temperature of from 200.degree. C. to 800.degree. C.,
through pairs of disks which are each formed by two disks, to an
exit opening. The second flow channel of a second medium,
especially a cooling medium, in particular a liquid cooling medium
such as water, leads through at least one exit and through at least
one housing element, including in particular a second housing
element, and through the opening, owing to a setting-apart of
adjacent pairs of disks and disk edge surfaces, to an exit in a
second housing element. A respective first disk is connected to a
second disk, especially with a material fit such as soldering,
welding, bonding. The first disks, the second disks and the housing
element surround the second flow channels. The first housing
element is cooled by the second medium, especially cooling medium
such as liquid coolant, cooling water, air, refrigerant, especially
of an air conditioning system. This reduces thermal stresses. The
heat exchanger, especially the exhaust gas heat exchanger, is much
more durable. The housing element can be made of a material which
is not heat-resistant and would be destroyed in particular at
temperatures of greater than 200.degree. C., especially at
temperatures of greater than 400.degree. C. In particular, the
plastics material or aluminum housing element can be manufactured
cost-effectively, thus considerably reducing the manufacturing
costs.
[0010] In an advantageous embodiment, the heat exchanger has a
first housing element around substantially all of which the second
medium, especially cooling medium, is able to flow and which
particularly advantageously cools the housing element, so almost no
thermal stresses occur or thermal stresses are advantageously
reduced and the durability is substantially increased and the
material costs are particularly advantageously lowered.
[0011] In an advantageous embodiment, the temperature of the first
medium, especially of the exhaust gas of an internal combustion
engine, prior to entering the heat exchanger is higher than the
temperature of the second medium, especially of the cooling medium,
prior to entering the heat exchanger. Despite a high temperature of
the uncooled exhaust gas, almost no thermal stresses occur on the
housing element which can particularly advantageously be made of an
inexpensive material.
[0012] In an advantageous embodiment, the first housing element is
made of a first material, especially aluminum or plastics material,
and the second housing element is made of another second material,
especially steel. In a particularly advantageous manner, both
housing elements are particularly advantageously cooled by the
cooling medium. The first material, aluminum, plastics material,
etc., is particularly advantageously inexpensive and leads
advantageously to a saving in weight and a lower overall space
requirement.
[0013] In an advantageous embodiment, the second housing element
has at least one housing opening, especially a first housing
opening for an entry of the first medium into the first flow
channel, especially a second housing opening for an exit of the
first medium from the first flow channel, especially a third
housing opening for an entry of the second medium into the second
flow channel and especially a fourth housing opening for the exit
of the first medium from the second flow channel.
[0014] In an advantageous embodiment, the first housing element and
the second housing element can be opened in at least one stacking
direction of the first disks and the second disks. The disks and
pairs of disks can be mounted and manufactured particularly
advantageously.
[0015] In an advantageous embodiment, the first housing element and
the second housing element are interconnected or interconnectable
with a material fit, especially by soldering, welding, bonding,
etc., and/or interconnected or interconnectable with a form fit,
especially by screwing, clipping, or by deformation such as
folding, crimping, bordering, etc.
[0016] In an advantageous embodiment, the first housing element and
the second housing element are particularly advantageously sealed
relative to one another using a sealing element, especially an
O-ring, a square ring, a film seal, etc.
[0017] In an advantageous embodiment, the first disk and/or the
second disk has projections, especially turbulence-generating
elements between adjacent disks and/or pairs of disks, thus
particularly advantageously improving the transfer of heat between
the first medium and the second medium.
[0018] In an advantageous embodiment, the first disks and/or the
second disks each have at disk ends at least one cup, as a result
of which adjacent pairs of disks are particularly advantageously
interconnected and the first medium can flow particularly
advantageously.
[0019] In an advantageous embodiment, the cups each have at least
one cup opening, especially for the passage of the first cooling
medium.
[0020] In an advantageous embodiment, a respective first disk and a
respective second disk form a pair of disks and are interconnected
particularly advantageously with a material fit, especially by
soldering, welding, bonding, etc., and form a pair of disks.
[0021] In an advantageous embodiment, a plurality of pairs of disks
can particularly advantageously be stacked on one another and are
interconnected at cup opening edges with a material fit, especially
by soldering, welding, bonding, etc.
[0022] In an advantageous embodiment, the pairs of disks form the
first flow channels for the first medium, especially for exhaust
gas to be cooled, the exhaust gas to be cooled flowing particularly
advantageously within a number of pairs of disks.
[0023] In an advantageous embodiment, two adjacent pairs of disks
are arranged set apart from one another. This forms the second flow
channels of the second medium, especially cooling medium,
particularly advantageously between adjacent pairs of disks.
[0024] In an advantageous embodiment, the second flow channels of
the second medium, especially cooling medium, are formed between
the first housing element and a disk pair edge surface. The disk
pair edge surface is in particular the outer surface of the outside
of the interconnected pairs of disks of the first and second
disks.
[0025] In an advantageous embodiment, third flow channels of a
third medium are formed next to the second flow channels, thus
allowing the exhaust gas particularly advantageously to be cooled
in two successive cooling stages.
[0026] In an advantageous embodiment, the third flow channels of
the third medium are particularly advantageously formed between the
first housing element and the disk pair edge surfaces.
[0027] In an advantageous embodiment, the third flow channels are
separated from the second flow channels, especially by at least one
partition element. In this way, the at least two cooling circuits
are particularly advantageously separated and the first housing
element is particularly advantageously cooled, as a result of which
thermal stresses are particularly advantageously reduced and the
durability of the heat exchanger is particularly advantageously
increased, and the manufacturing costs are particularly
advantageously reduced.
[0028] In an advantageous embodiment, the second medium, especially
cooling medium, of a high-temperature cooling circuit is able to
flow through the second flow channels and a third medium,
especially cooling medium, of a low-temperature cooling circuit is
able to flow through the third flow channels.
[0029] A heat exchanger has a first housing element which is an
integral part of at least one other component, especially a water
jacket, a cylinder head of an internal combustion engine, a water
tank of a coolant cooler, etc. The heat exchanger can in this way
be integrated into an existing component, thus significantly
reducing in particular the overall space, especially in the front
region of a vehicle.
[0030] A heat exchanger has a second housing element but no first
housing element. The heat exchanger is used in particular for
cooling exhaust gases, with at least one first flow channel of a
first medium, especially a gas, with at least one second flow
channel of an at least second medium, especially a cooling medium,
with at least one first disk, with at least one second disk, the
first disk and the second disk being interconnected and forming the
first flow channel of the first medium, with at least one second
housing element.
[0031] A modular heat exchanger system has at least one heat
exchanger, especially for cooling exhaust gases, with at least one
first flow channel of a first medium, especially a gas, with at
least one second flow channel of an at least second medium,
especially a cooling medium, with at least one first disk, with at
least one second disk, the first disk and the second disk being
interconnected and forming the first flow channel of the first
medium, with at least one housing element, especially a first
housing element and a second housing element forming, together with
the first disk and the second disk, the second flow channel of the
second medium, wherein the first housing element can be cooled by
the second medium.
[0032] In a further advantageous embodiment, the cooler consists of
a set of disks. The set of disks consists of pairs of disks which
form a flow channel for a first medium and have
turbulence-generating structures, especially turbulence inserts.
The turbulence inserts can be formed either by impressions in the
disks or preferably by a soldered-in turbulence metal sheet. The
gaps between two disks form channels for a second medium. Each two
adjacent pairs of disks are at both ends in flow connection with
the adjacent pairs of disks via lateral openings which can be
arranged in a dome or cups projecting out of a disk or out of both
disks in order to bridge the gap between the pairs of disks. The
pairs of disks are formed in particular from two identical disks.
The gaps between the disks can each be supported relative to one
another by knobs, dimples or inserted elements such as, for
example, metal sheets, ribs, support elements. The supporting
elements can be welded, soldered or bonded to one another or held
by a form fit. Knobs or dimples are impressed into the disk
material. They can also project as elongate beads to improve the
flow distribution of the second medium in the flow channel.
[0033] In a further embodiment, the first medium will be a medium
to be cooled and especially a hard medium, conventionally a hot gas
such as exhaust gas or compressed charge air, and the second medium
will be a liquid cooling medium such as coolant of an internal
combustion engine or, in future applications, coolant of a cold
circuit. The coolant can be guided parallel or counter to the main
flow direction of the first medium (coflow or counterflow). The
design is particularly suitable for counterflow connection, which
is preferable in terms of thermodynamics, as it is distinguished by
a particularly low risk of boiling in the coolant, because suitable
guidance of the coolant allows dead water zones to be substantially
prevented.
[0034] In a further embodiment, the flow channel for the second
medium can be divided into two portions which are supplied with
coolant from differing cooling circuits, in particular one circuit
with warmer coolant at the entry end of the first medium and one
low-temperature cooling circuit at the exit end of the first medium
to increase the cooling power. The circuits can be separated, for
example, by a transverse bead which is impressed into the disks,
the channel remaining laterally free being blocked with sufficient
tightness by a component (a type of grid) which is form-fitted to
the pair of disks. Grids of this type can also be configured in
such a way that no transverse beads are required in the disks;
instead, the channel is blocked by at least two grids which are
inserted into the bundle of disks on the opposing sides. These
grids can, however, again be positioned by means of beads or knobs,
especially during a soldering process or if no rigid connection to
the bundle of disks is produced.
[0035] In a further embodiment, the channel for the second medium
can be formed outwardly by a housing jacket or by a cavity, through
which coolant flows, in another component, for example in the water
jacket or cylinder head of the engine unit, in the water tank of a
coolant cooler (in-tank) or in a combination housing through which
coolant flows and into which a plurality of heat transfer means are
integrated and combined to form a module.
[0036] In a further advantageous embodiment of the heat transfer
means with its own housing jacket, use is made of an at least
two-part housing jacket which opens substantially in the stacking
direction of the bundle of disks. A lid or cover plate, which
closes off the bundle of disks at the top, and a trough, into which
the bundle of disks is inserted, constitute the basic components of
the housing jacket. The lid and trough are in a particularly
beneficial embodiment peripherally interconnected, especially
soldered. The connections for the second medium are located at the
opposing ends of the housing and can be arranged in any desired
arrangement in one of the parts of the housing. Further connections
are provided in the center of the cooler to integrate a plurality
of cooling circuits. The connections for the first medium can be
located, on the one hand, on the same side of the heat transfer
means, i.e. for example both in the lid or both in the housing
trough. Furthermore, also possible is a diagonal throughflow in
which either the entry or the exit is located in the lid and the
other connection in the housing trough. Finally, guiding the first
medium in a U-flow is also possible. In this case, not all pairs of
disks are in flow connection at the entry for the first medium;
instead, this connection is prevented at one point between two
specific pairs of disks in that between these pairs either the
lateral connecting openings are not formed or there is inserted an
additional metal sheet which obstructs the connection and uncouples
the pairs of disks located at the entry from the pairs of disks
located further below. The first medium flows through the cooler in
the disks, which are interconnected below the entry up to the
break, in the longitudinal direction of the heat exchanger. At the
other end, all pairs of disks are interconnected and the first
medium flows into the pairs of disks which are uncoupled at the
entry end and flows back to the entry end where it leaves the heat
transfer means, on the side opposing the entry, through an exit.
The housing must withstand the pressure of the second medium. In
the direction perpendicular to the stacking direction of the heat
transfer means, the housing is not soldered to the bundle of disks.
It may be beneficial to increase the pressure stability of this
side by means of impressed beads in the housing.
[0037] In a further advantageous configuration, the disks are
particularly advantageously prevented from moving transversely to
the stacking direction during the soldering process. The disks can
at certain points be form-fitted to the housing contour.
[0038] Furthermore, it may be advantageous if respective pairs of
disks with a turbulence insert are preproduced in a first joining
step to form channels for the first medium. These pairs of disks
can be interconnected by means of a form-fitting embodiment with or
without compression, by means of a clamping or crimping connection,
the connection basically being a folded connection, by means of
weld points or adhesive points or the like. This procedure can
greatly simplify the encasing process (stacking of the individual
parts, especially the disks) and the process safety of the joining
process as a whole can be increased.
[0039] Embodiments without an independent housing jacket of the
heat exchanger are also particularly advantageous. In this case,
the bundle of disks is closed off at the top by a cover plate into
which the entry and exit for the first medium are integrated. At
the bottom there is generally a base plate. Fastening at the site
of installation is carried out by means of a tight joint between
the cover plate and the component forming the cavity through which
coolant flows, for example via a screw connection, crimping or
bordering connection, clamping connection, the seal generally being
produced by means of a sealing element, for example an O-ring. This
type of linking can also be utilized to embody an independent
cooler housing jacket in that, for example, a cover plate made of a
steel or aluminum material is connected in the aforementioned
manner to a water-guiding plastics material housing. For
connection, use may in this case be made, for example, of a
bordering connection or a screw connection with injected threaded
sockets in a plastics material component and slots in the cover
plate. Furthermore, the screwing can be carried out by means of
through-holes in the housing and screwing in the cover plate
(threads in passages, self-tapping screws in a smooth passage,
threaded bushes).
[0040] In a further advantageous embodiment, the flow channel for
the second medium (housing or cavity in another component) is
advantageously configured in such a way that it extends in the
region in which the channel cross section is markedly restricted by
the dome at the disk ends and subsequently tapers toward the center
of the heat transfer means, thus urging the 2.sup.nd medium into
the channels between the pairs of disks. The distribution of the
second medium can thus be significantly improved. A likewise highly
beneficial possibility for achieving optimum distribution of the
2.sup.nd medium is the funnel-shaped configuration of the
transition of the disks from the domes to the channel for the
1.sup.st medium. In this way too, the 2.sup.nd medium is urged into
the channels between the pairs of disks.
[0041] In a further advantageous embodiment, an uncooled bypass
channel, for example in the form of one or more pairs of disks, can
be provided in the cooler. Air gap insulation of the bypass channel
is preferably utilized to achieve the substantially uncooled
conveyance of the first medium (in particular recirculated exhaust
gas of an internal combustion engine). Exemplary embodiments of air
gap-insulated bypass tubes:
[0042] outer casing soldered from half-shells, a tube with support
knobs inserted on the inside;
[0043] outer and inner casings soldered from half-shells;
[0044] soldered to the lid or cover disk is a further metal sheet
forming, together with the lid/cover disk, a channel which is used
as the bypass channel (non-air gap-insulated);
[0045] on the side of the cover metal sheet lid facing the bundle
of disks, a further metal sheet is soldered on and an additional
gas channel formed (non-air gap-insulated);
[0046] a bypass tube, which can be in one piece or two pieces, is
soldered to the lid/cover disk, beads or knobs preventing planar
abutment in the bypass channel and/or in the cover sheet/lid;
[0047] on entry or exit of gas in the housing trough, the bypass
can be formed with additional metal sheets or tubes in the same
ways as described for the lid/cover plate;
[0048] on entry or exit of gas in the lid/cover plate and the other
gas connection in the housing trough, the bypass can be attached to
one of the two parts and the bypass can also include the transverse
connection between the pairs of disks;
[0049] in the U-flow, a bypass solution can be provided as a result
of the fact that the uncoupling is configured so as to be able to
switch between the pairs of disks on the entry side and on the
opposing side, for example by means of a rotary slide which
releases the direct path from the entry to the exit in the event of
a bypass and breaks off the passage in normal cooler mode, so the
cooler is flowed through in a U-flow.
[0050] In a further advantageous embodiment, the bypass valve used
is a conventional, external valve with separate feed lines to the
bypass and to the heat-transferring flow channels. However, use may
also be made of flaps or valves which are integrated into the entry
nozzle or exit nozzle. These may, in particular, also be configured
as a flap or rotary slide. Particularly advantageous is the
embodiment of the bypass flap as a combination valve in which, in
addition to switching between bypass and normal cooler mode, both
paths can also be completely obstructed and the amount of
recirculated exhaust gas can thus be regulated.
[0051] In a further advantageous embodiment, especially in an
embodiment without a housing, a heat transfer means is used in the
crossflow between the first and the second medium. Heat exchangers
of this type could preferably be used in the cooling module of a
motor vehicle. In this case, the medium to be cooled would be
guided as the first medium through the heat exchanger and cooling
air is used as the second medium. A heat transfer means of this
type can be fastened using the cover plate or the base plate within
a cooling module or in each case to other components of the cooling
module; however, it can also have its own frame which, on the one
hand, includes the cover plate and base plate while still
establishing a connection between the cover plate and base plate
and thus ensuring rigidification of the heat exchanger. The
connection between the cover plate and base plate can be provided
either by additional components connected to the cover plate and
base plate or by means of suitable configuration of the cover plate
and base plate, for example as U-shaped components which open in
opposition to one another and jointly form the frame. This frame
can additionally be connected to the individual pairs of disks.
This increases, in particular, the vibration strength of the
component. The connection can be produced by a form fit, although
it can also be provided, in particular, by a tight soldered joint.
The heat transfer means is then fastened to the frame and/or via
the connections for the first medium. Instead of arranging the heat
transfer means in a cooling module, it can also be fastened in the
chassis, i.e. in particular to the frame of a motor vehicle, in
exceptional cases so as to be secured to the engine. Preferably, a
component of this type can be used as a direct exhaust gas cooler.
However, applications as a charge air cooler, coolant cooler, oil
cooler, condenser, etc. are also beneficial.
[0052] Further advantageous configurations emerge from the
sub-claims and from the drawings.
[0053] Exemplary embodiments are illustrated in the drawings and
will be described hereinafter in greater detail. In the
drawings:
[0054] FIG. 1 is an exploded view of a heat exchanger;
[0055] FIG. 2 is an isometric representation of the heat
exchanger;
[0056] FIG. 3 is a section A-A through the heat exchanger;
[0057] FIG. 4 is a section B-B through the heat exchanger;
[0058] FIG. 5 is an exploded view of a further heat exchanger;
[0059] FIG. 6a is a plan view of a further exemplary embodiment of
the heat exchanger with a shaped formation in the entry or exit
region of the housing element;
[0060] FIG. 6b is an isometric representation of a further
exemplary embodiment of the heat exchanger with a shaped formation
in the entry or exit region of the housing element;
[0061] FIG. 7 shows a further exemplary embodiment of the heat
exchanger as a U-flow cooler;
[0062] FIG. 8 shows a further exemplary embodiment of the heat
exchanger as a double heat exchanger;
[0063] FIG. 9 shows a further exemplary embodiment of the heat
exchanger with two-stage cooling;
[0064] FIG. 10 shows a further exemplary embodiment of the heat
exchanger as a double heat exchanger, the first partial heat
exchanger being cooled using a high-temperature circuit and the
second partial heat exchanger being cooled using a low-temperature
circuit;
[0065] FIG. 11 shows a further exemplary embodiment of a heat
exchanger in a crossflow configuration;
[0066] FIG. 12 shows a further exemplary embodiment of a heat
exchanger with an integrated bypass channel and a rotary slide for
activating flowing through the bypass channel and/or the heat
exchanger portion; and
[0067] FIG. 13 shows a further exemplary embodiment of a heat
exchanger with an integrated bypass channel which is formed with
air gap insulation.
[0068] FIG. 1 is an exploded view of a heat exchanger. The heat
exchanger 1 has a first housing element 6, 7 and a second housing
element 8. The housing element 6, 7 accommodates first disks 4 and
second disks 5. The first disks 4 and the second disks 5 are
arranged substantially parallel to one another and stackable. A
first disk 4 forms together with a second disk 5 a pair of disks
22. The first and second disks are interconnected with a material
fit, especially by soldering, welding or bonding. Likewise,
adjacent pairs of disks 22 are interconnected, especially in cups
20 at both disk ends 19 of the disks 4, 5 or the pairs of disks 22,
with a material fit, especially by soldering, welding or bonding.
The disks 4, 5 and the pairs of disks have cup openings 21. The
first housing element 6, 7 is connected to the second housing
element with a material fit and/or with a form fit. The second
housing element has a first housing opening 10 for the entry 11 of
the first medium. Through the first flow channel 2 the first
medium, especially the hot exhaust gas, flows into the pairs of
disks 22 through the cup openings 21, flows through the pairs of
disks in the flow channel 2 formed in the interior and flows
through a second housing opening 12 in the housing element 8, out
of said housing element via the exit 13. The pairs of disks are
stackable in the stacking direction S. The housing element 8 has a
third housing opening 14 through which cooling medium, especially
liquid coolant, cooling water, gas or coolant, in particular of an
air conditioning system, passes via an entry 15 into the first
housing element 6, 7 and cools said first housing element, so
substantially no thermal stresses are produced. The second cooling
medium flushes the outsides of the disks 4, 5 and the pairs of
disks 22 and also those of the disk pair edge surfaces 24. It flows
through openings formed by the set-apart pairs of disks, as a
result of which heat is exchanged between the exhaust gas to be
cooled. Second flow channels 3 of the cooling medium are likewise
formed between the first housing element 6, 7 and the disk pair
edge surfaces 24, as a result of which the housing element 6, 7 is
substantially cooled. The cooling medium leaves a fourth housing
opening 16 in the housing element 8 via an exit 17. The heat
exchanger 1 can be integrated into a modular system as a module.
The heat exchanger can be integrated into a cooling module. A
cooling module comprises, in particular, a plurality of heat
exchangers, especially coolant coolers, oil coolers, charge air
coolers, exhaust gas coolers, heat exchangers of an air
conditioning system.
[0069] FIG. 2 is an isometric representation of the heat exchanger.
Like features are provided with the same reference numerals as in
FIG. 1. The housing element 6, 7 accommodates in the interior
thereof the disks 4, 5 and the pairs of disks 22. The first housing
element 6, 7 is connected to the second housing element 8 with a
material fit by soldering, welding, bonding, etc. and/or with a
form fit by bordering, corrugated slot bordering, crimping,
folding, clipping, etc. In one embodiment (not shown), both housing
elements are sealed relative to one another by means of a sealing
element, especially an O-ring, etc.
[0070] FIG. 3 shows a section A-A through the cup openings 21 in
the heat exchanger. Like features are provided with the same
reference numerals as in the preceding figures.
[0071] FIG. 4 shows a section B-B through the heat exchanger. Like
features are provided with the same reference numerals as in the
preceding figures. Adjacent pairs of disks are set apart from one
another by projections, especially turbulence inserts or
turbulence-generating elements 18. In particular, the transfer of
heat between the first medium and the second medium is improved.
Likewise, projections, especially turbulence inserts or
turbulence-generating elements 18, are arranged within the pairs of
disks and connected to the disks 4, 5 especially with a material
fit, by soldering, welding, bonding, and/or project therefrom by
deformation. The pairs of disks can both laterally be in contact
with the housing element 6 and be at a defined distance from one
another. Section B-B shows a pair of disks in contact with the
housing element.
[0072] FIG. 5 is an exploded view of a further heat exchanger. Like
features are provided with the same reference numerals as in the
preceding figures. The heat exchanger 25 does not have a first
housing element 8. The heat exchanger 25 can be integrated into a
modular system as a module. In particular, it is arranged adjacent
to a fan 26 and able to have air L flow through it. The heat
exchanger can be integrated into a cooling module. A cooling module
comprises, in particular, a plurality of heat exchangers,
especially coolant coolers, oil coolers, charge air coolers,
exhaust gas coolers, heat exchangers of an air conditioning
system.
[0073] FIG. 6a is a plan view and FIG. 6b is an isometric
representation of a further exemplary embodiment of a heat
exchanger 60 with a shaped formation in the entry or exit region of
the housing element. Like features are provided with the same
reference numerals as in the preceding figures.
[0074] In the heat exchanger 60, the cooling medium 17 is optimally
distributed in the entry region by means of a shaped formation 61,
which is in particular formed as a bulge, in the housing element 6,
7 over the entire width of the pair of disks. The entry region of
the first medium is thus cooled over its entire circumference.
[0075] FIG. 7 shows a further exemplary embodiment of the heat
exchanger as a U-flow cooler. Like features are provided with the
same reference numerals as in the preceding figures.
[0076] The heat exchanger 70 is shown in a sectional view. The heat
exchanger is formed as what is known as a U-flow embodiment. In
this case, the cooling medium 15, 17 is conveyed axially, whereas
the first medium flows through the heat exchanger in a U-shaped
manner. This is achieved by inserting a separating metal sheet 71
between two pairs of disks. The separating metal sheet has no
opening in the region of the entry/exit of the first medium (cup
region). Conversely, on the opposite side, a suitable opening is
present in the cup region, so the first medium can flow from the
upper half of the cooler into the lower half. In this case, the
position of the separating metal sheet 71 is arranged in other
embodiments (not shown) above or below the center, so either
above/below the separating metal sheet the same number of pairs of
disks are present or the pairs of disks are non-uniformly
distributed.
[0077] FIG. 8 shows a further exemplary embodiment of the heat
exchanger as a double heat exchanger. Like features are provided
with the same reference numerals as in the preceding figures.
[0078] FIG. 8 is a section of the heat exchanger 80, the
above-mentioned separating metal sheet 81 being completely closed.
This allows very simple embodiment of a heat exchanger formed as a
double heat exchanger. Two media, a first medium and a third
medium, in particular two different media, will be cooled in the
double heat exchanger 80. For this purpose there are, both at the
lower end and at the upper end of the stack of disks including the
disks 4, 5, openings 82, 83, 84 and 85 for the entry/exit of the
first medium and the third medium. The two media flow in this case
in coflow or in counterflow.
[0079] Reference numeral 86 denotes the exit for the third medium.
Reference numeral 87 denotes the entry for the third medium. In
another exemplary embodiment, the entry 87 and the exit 86 are
swapped over.
[0080] FIG. 9 shows a further exemplary embodiment of the heat
exchanger with two-stage cooling. Like features are provided with
the same reference numerals as in the preceding figures.
[0081] The heat exchanger 90 has two cooling media circuits. The
first cooling circuit is a high-temperature circuit. The second
circuit is a low-temperature circuit. The coolant in the
high-temperature circuit has a higher temperature than the coolant
in the low-temperature circuit. A high- and low-temperature coolant
circuit may thus be produced in a heat exchanger. The separating
metal sheet 91 is configured as a grid. The separating metal sheet
91 is pushed onto the pairs of disks, especially orthogonally to
the longitudinal axis SLA of the disks. Furthermore, the housing
element has four openings 92, 93, 94 and 95 for the exit and/or
entry of the two cooling media.
[0082] Reference numeral 97 denotes the entry for the second
cooling medium, in particular of the low-temperature circuit.
Reference numeral 96 denotes the exit for the second cooling
medium. In another exemplary embodiment, the entry 97 and the exit
96 are swapped over.
[0083] In another variation, the heat exchanger 90 is configured as
a U-flow cooler, the first and the second cooling medium performing
a U-flow, like the exemplary embodiments in FIGS. 7 and 8.
[0084] FIG. 10 shows a further exemplary embodiment of the heat
exchanger as a double heat exchanger. Like features are provided
with the same reference numerals.
[0085] The heat exchanger 100 has a first partial heat exchanger
101 which is cooled using a high-temperature circuit and a second
partial heat exchanger 102 which is cooled using a low-temperature
circuit. In another variation, the high-temperature circuit and
low-temperature circuit are swapped over.
[0086] At the entry 103 the second cooling medium, in particular of
the low-temperature circuit, enters the partial heat exchanger 102,
flows therethrough and leaves the partial heat exchanger through
the exit 104. The exit 104 and entry 103 are swapped over in
another exemplary embodiment.
[0087] The third medium enters the partial heat exchanger 102 via
the media entry 105, flows through said partial heat exchanger and
leaves it via the media exit 106. In another variation, the media
exit 106 and the media entry 107 are swapped over.
[0088] The separating plate 107 separates the first partial heat
exchanger 102 and the second partial heat exchanger 103, especially
in terms of flow.
[0089] FIG. 11 shows a further exemplary embodiment of the heat
exchanger illustrated in FIG. 5 in a crossflow configuration.
[0090] The heat exchanger 110 does not have any housing and it is,
in particular, configured as a crossflow heat exchanger. In this
case, the flows between which heat is transferred intersect at
least in certain regions. In this case, a cooling rib is located
between the pairs of disks 4, 5 forming the flow channels for the
first medium. The cooling rib is rigidly connected, for example
soldered, bonded, mechanically joined, etc., to the pairs of disks
4, 5, so as to ensure sufficient conduction of heat between the
pairs of disks 4, 5 and the rib. The rib 111, especially the
corrugated rib, is in this case flowed through by a cooling medium,
for example air. The air is moved by means of a cooling medium
conveyor L, for example a fan L. In another exemplary embodiment,
no rib is provided. In this case, a turbulence-generating
structure, which improves the transfer of heat, is impressed into
the disks. In another embodiment, the crossflow configuration is
configured with a housing. This provides the advantage of allowing
this heat transfer means to be attached not only in the front
module of the vehicle, i.e. in the front vehicle region which is
struck by the headwind, but rather, irrespective thereof, at a
suitable location in the vehicle with its own cooling media
conveyor.
[0091] FIG. 12 shows a further exemplary embodiment of a heat
exchanger 120 with an integrated bypass channel and a rotary slide
for activating flowing through the bypass channel 121 and/or the
heat exchanger portion 122. Like features are provided with the
same reference numerals as in the preceding figures.
[0092] The rotary slide 123 assumes a bypass position and/or a
cooler throughflow position. The rotary slide 123 has at least one
recess.
[0093] In the bypass position, the bypass is flowed through. In the
cooler position, the heat exchanger portion 122 is flowed through.
In another embodiment, the bypass 121 and heat exchanger portion
are swapped over.
[0094] The rotary slide 123 can also assume a position in which
both the bypass 121 and the heat exchanger portion are flowed
through. The rotary slide rotates through an angle of rotation,
especially of 90.degree., in order to pass from the bypass position
into the heat exchanger throughflow position.
[0095] FIG. 13 shows a further exemplary embodiment of a heat
exchanger with an integrated bypass channel 131 which is formed
with air gap insulation. Like features are provided with the same
reference numerals.
[0096] The bypass channel 131 is used for the bypassing of medium,
so the medium does not flow through the heat exchanger. The
insulation, especially air gap insulation, serves to prevent or to
reduce the transfer of heat between the bypass channel 131 and the
heat exchanger.
[0097] In further embodiments of FIG. 1 to 13,
turbulence-generating elements or the turbulence inserts are
configured as web ribs.
[0098] Despite their passage cross sections, which are in principle
smaller than those of other inserts, turbulence inserts with web
ribs have a comparatively low tendency to collect deposits. In
principle, there was a risk that turbulence inserts with web ribs
would lead increasingly to the blockage of individual passage
channels owing to the delicate structure of the web ribs. However,
this is the case to a surprisingly low extent, especially if the
webs of the web ribs are relatively short. A possible explanation
of this might be that the turbulent flow, which is present over
large parts of the web rib insert, of the exhaust gas reduces
deposition of particles, whereas there are formed flows which are
ordered in longer, uniform channels and promote the deposition of
particles in proximity to the wall owing to the flow speed which is
very low at this location.
[0099] In a preferred embodiment, the webs of the web ribs have a
length which is no more than about 10 mm, preferably no more than
about 5 mm and particularly preferably no more than about 3 mm.
Depending on the overall space and internal combustion engine in
question, specific demands may be placed on the drop in pressure in
the exhaust gas heat exchanger. Depending on these demands, one of
the aforementioned length ranges may be preferred.
[0100] Also preferably, a density of the web ribs transversely to
the exhaust gas flow direction is between about 20 web ribs/dm and
about 50 web ribs/dm, preferably between about 25 web ribs/dm and
45 web ribs/dm. These web rib densities have proven to be
particularly suitable in trials. In particular, the web ribs strike
particularly advantageously a good compromise between the risk of
blockage and the cooling power.
[0101] With regard to the height of the web ribs, it should be
borne in mind that, in the case of high heights, there are
available only relatively small primary surface areas, i.e.
surfaces cooled by coolant, via which all of the heat must be
released into the coolant. In the case of relatively small primary
surface areas, the risk of boiling then rises in the case of a
liquid coolant. In addition, the effectiveness of the inserts
decreases as the height of the web ribs increases. A preferred
height of the insert or web rib is therefore between about 3.5 mm
and about 10 mm, particularly preferably between about 4 mm about 8
mm and especially preferably between about 4.5 mm and about 6
mm.
[0102] In a preferred development of the device according to the
invention, provision may be made for an oxidation catalyst to be
arranged before the plurality of flow channels. A catalyst of this
type generally allows the particle sizes, particle densities and
the proportions of hydrocarbons in the exhaust gas to be reduced by
means of oxidation. Additionally or alternatively, provision may in
this case be made for the inserts themselves to be provided with a
coating for the catalytic oxidation of the exhaust gas. Especially
in conjunction with oxide-catalytic means, the beneficially usable
density of the web ribs transversely to the exhaust gas flow
direction can be more than about 50 web ribs/dm, especially about
75 web ribs/dm. This would provide a particularly high heat
exchanger power for a given overall space without giving rise to
the long-term risk of blockage caused by deposits.
[0103] In a particularly preferred embodiment, the web ribs have
oblique teeth. Oblique-toothed ribs have been found in experiments
to be particularly suitable for ensuring long-term stability of the
exhaust gas heat exchanger with respect to deposits. In this case,
in a preferred embodiment, the angle between the web walls and a
main direction of the web ribs is between about 1.degree. and about
45.degree.. In a particularly preferred embodiment the angle is
between about 5.degree. nd about 25.degree., wherein it can in an
alternative preferred embodiment also be between about 25.degree.
and about 45.degree.. The former value range of from 5.degree. to
25.degree. is particularly suitable in conventional applications
which are highly sensitive to losses in pressure, the latter value
range being suitable to achieve an optimized power density,
especially in applications which are less sensitive to losses in
pressure.
[0104] Generally, in the optimization of an insert with
oblique-toothed web ribs, a correlation may be identified between
the angle of the walls and a longitudinal division of the web rib.
In this case, in particular, optimum embodiments at small angles
can have larger divisions l than optimized embodiments with large
angles. Small angles of attack, in particular, can result in
embodiments with a moderate loss in pressure. Large angles of
attack, in particular, can result in embodiments with optimized
power density. The longitudinal division can be larger in the case
of small angles of attack in particular; in the case of large
angles of attack, the longitudinal division can in particular be
smaller in order to obtain optimized embodiments.
[0105] In a preferred embodiment, the device is configured as a
stacked-disk heat exchanger. This embodiment is particularly
expedient both with regard to the width of a flow channel and with
regard to the cost-effective production and combinability of a heat
exchanger housing with web rib inserts. Alternatively, the device
can however also be configured as a tube bundle heat exchanger or
as another form of heat exchanger known per se.
[0106] It is generally preferable for the insert to be made of a
stainless steel, especially an austenitic steel, to prevent
corrosion caused by the aggressive exhaust gas.
[0107] In a further advantageous configuration aluminum materials
can be used, wherein a suitable corrosion prevention means, such as
in particular an alloy and/or a coating, can then particularly
advantageously be provided.
[0108] In an advantageous development, the insert is made of
aluminum. An aluminum insert has a particularly low weight.
Particularly advantageously, the aluminum insert can be formed by
means of alloying or coating to prevent corrosion.
[0109] Depending on the flow parameters, especially the Reynolds'
number, the length of the run-in region of the flow channels,
especially tubes and/or pairs of stacked disks, l/s is from approx.
2.5 to 5 and the length of the web ribs must be selected so as to
be below this limit value. S denotes the central passage width
between two webs and is thus b/2-t, wherein t denotes the thickness
of the metal sheet. This results in a required ratio of l/s<4,
in particular l/s<2. If there is a high risk of blockage
resulting from the critical exhaust gas composition, l/s<1.5, in
particular l/s<1, should be selected.
[0110] Oblique positioning of the webs gives rise on the twist side
to a higher flow speed on the wall, which counteracts the
deposition of soot. A further important advantage of
oblique-toothed web ribs is that, in cases in which a low density
of the web ribs is required in the flow transverse direction to
prevent blockages, especially in the case of a disadvantageous
exhaust gas composition, sufficient cooler power can be achieved
despite the small surface area of the ribs.
[0111] The stacked disk heat exchanger according to the invention
comprises an outer housing with a lid, there being provided an
entry and an exit for the exhaust gas and also an entry and an exit
for a liquid coolant. A plurality of disk elements are provided
within the housing, each of the disk elements being composed of an
upper half and a lower half. By means of turned-up collars, the
disk elements are welded to one another and to the housing in such
a way that the coolant flows in each case between the two halves of
a disk element from the inlet to the outlet. An insert (not shown)
with web ribs is arranged in each case between two disk elements,
the gap between two disk elements forming a respective flow channel
for the exhaust gas. The inserts have not been shown for the sake
of clarity. The inserts are made of a stainless steel. To improve
the thermal contact between the inserts and the disk elements or
the housing, the inserts can be welded or soldered to the
aforementioned elements in a planar manner.
[0112] In a further embodiment, the turbulence insert is made of a
thin sheet metal material into which parallel web ribs are
introduced using shaping measures. Each of the web ribs comprises a
number of webs which are arranged in succession in the exhaust gas
flow direction. Each two webs which are arranged in succession in
the exhaust gas flow direction are arranged offset from one another
by half a web width transversely to the exhaust gas flow direction,
so each web is followed by a cutting edge with a subsequent web. In
the present example, the walls are oriented parallel to the
direction of flow of the exhaust gas and form an angle of 0.degree.
with an axis B of the web ribs or the main direction of flow of the
exhaust gas A. A web rib insert of this type is referred to as a
straight-toothed web rib.
[0113] In a first exemplary embodiment, the length l of a web is
about 4 mm. The width b of an individual web rib is defined as the
width of the repeating unit of the periodic structure transversely
to the main direction of flow of the exhaust gas. The web rib
density 2/b is in the present example about 40 web ribs/dm. The
width b of a web rib is thus about 5 mm.
[0114] The height h of the web ribs corresponds to the distance
between two adjacent disk elements of the heat exchanger and is in
the present case about 5 mm.
[0115] In a further configuration of the web rib insert, the
lateral walls of the individual webs are in this case not oriented
parallel to the main direction B of the web ribs. Instead, each of
the walls of the webs enclose with the main direction B of the web
ribs an angle W of about 30.degree.. The further dimensions of the
oblique-toothed web rib inserts correspond to the dimensions of the
straight-toothed web rib.
[0116] A suitable longitudinal division l for corresponding angles
of the walls W is provided by suitable embodiments at 10.degree.
with longitudinal divisions l of<approx. 10 mm, at 20.degree.
with l<approx. 6 mm, at 30.degree. with l<approx. 4 mm and at
45.degree. with l<approx. 2 mm. The minimum longitudinal
division l is in the case of all angles approx. 1 mm. The
admissible extent of the channel l/s lies substantially within the
same limit as for a straight-toothed web rib, wherein s denotes the
web distance transversely to the main direction of flow B.
Generally speaking, longitudinal divisions l of<1 mm are
difficult to establish for reasons relating to production.
[0117] The features of the various exemplary embodiments may be
combined with one another as desired. The invention can be used
also in fields other than those disclosed.
* * * * *