Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02871787 2014-10-28
WO 2013/164083
PCT/EP2013/001280
Heat Exchanger Comprising a Supply Channel
The present invention relates to a heat exchanger for a motor vehicle,
according to the
features in the preamble of Claim 1.
From the prior art it is known to use heat exchangers, in particular in motor
vehicles, in
order to cool components by means of a medium and/or in order to remove heat
from a medium
in a controlled manner. In this way it is possible, for example, to cool the
cooling water of an
internal combustion engine of a motor vehicle in a controlled manner by means
of a second
medium, in particular air. However, it is also possible to cool the exhaust
gas of a motor vehicle,
for example, in order to feed the cooled exhaust gas itself back into the
combustion process.
From DE 434 34 05 Al, for example, a tube cluster heat exchanger is known, in
which at
one end a medium is introduced, which strikes a tube sheet and accumulates at
the tube sheet,
and then is led through heat exchanger tubes
CONFIRMATION COPY
located in the tube sheet. In the cross flow principle, a second medium is
then introduced on the
outside onto a casing of the heat exchanger, it flows through the heat
exchanger and it exits the
heat exchanger again at an outlet side on the opposite side from the inlet of
the second medium.
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The disadvantage here is that, in the case of the use of such a tube cluster
heat exchanger
as exhaust gas heat exchanger, the tube sheet in particular is exposed at
least locally to the high
temperatures of the flowing exhaust gas.
Therefore, the problem of the invention is to provide a heat exchanger for a
motor vehicle
which, with a cooling power which remains at least constant, has a better
resistance of the
internal components to high temperatures of the media to be passed through.
The above-mentioned problem is solved according to the invention with a heat
exchanger
for a motor vehicle by the features in Claim 1.
Advantageous embodiment variants of the present invention are the subject
matter of the
dependent claims.
The heat exchanger according to the invention for a motor vehicle, wherein the
heat
exchanger comprises an outer casing and heat exchanger tubes are arranged in
the outer casing,
and a first medium can be fed on the end side into the casing, and a second
medium can be fed
via the lateral face to the casing, characterized in that, on the casing, on
the outside, a channel
that is at least partially peripheral is formed, wherein the second medium can
be led from a feed
line into the peripheral channel, and through openings in the casing, it
reaches the inner space of
the casing from the channel.
As a result, it becomes possible that, in the heat exchanger itself, which is
designed in
particular as a tube cluster heat exchanger, most particularly preferably as
an exhaust gas heat
exchanger for a motor vehicle, an end plate or perforated plate, also known as
tube sheet,
through which heat exchanger tubes pass, is cooled more satisfactorily. Now, a
first medium is
fed into the heat exchanger and discharged again on the opposite end side.
Here, the first medium
is led through the heat exchanger tubes. In the process, a second medium is
introduced, based on
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the countercurrent principle or else on the cross current principle or else on
the cocurrent
principle, into the heat exchanger from one side of the casing. However,
according to the
invention it is provided that the second medium not just led from one side at
points or else from
one side through the casing of the heat exchanger laterally to the heat
exchanger tubes located in
the casing of the heat exchanger, but is led instead first via a feed line in
the direction of the
casing, most particularly preferably in the direction of an end of the casing.
Here, it is then
provided according to the invention that a channel that is at least partially
peripheral, and in
particular completely peripheral, is formed, channel in which the second
medium first flows and
as a result is distributed around the casing.
In the channel itself, openings are provided, wherein the second medium, which
has
become distributed in the channel, can pass through the openings into the
interior of the casing.
As a result, it is ensured that the second medium strikes the heat exchanger
tubes not only on one
side or else at points, but penetrates instead on all sides from the outside
of the casing in
particular simultaneously and/or at approximately equal temperature, in
particular the flow
temperature, into the casing of the heat exchanger. In the case of a channel
arranged in the area
of the end of the casing, the second medium similarly flows around the tube
sheet, wherein the
second medium is preferably a cooling medium, most particularly preferably
cooling water.
The first medium, which is introduced on the end side into the heat exchanger
and thus
also strikes the tube sheet, ensures a strong heating of the tube sheet. In
particular, as first
medium, an exhaust gas, which can have exhaust gas temperatures of more than
600 C, at times
even more than 800 C, is led here through the heat exchanger. As a result of
the approximately
homogeneous cooling of the tube sheet with the second medium, an excessively
strong heating
of the tube sheet is avoided, and at the same time, since such a heat
exchanger is often thermally
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=
joined, in particular soldered, a one-sided distortion due to different
thermal expansions is
prevented. As a result, the longevity and the tightness of the heat exchanger
are increased,
wherein cost intensive and heat resistant materials do not need to be used,
since the tube sheet is
cooled more satisfactorily. Consequently, it is possible to produce the heat
exchanger with
improved cooling power in a clearly more cost effective manner.
In the context of the invention, the casing of the heat exchanger is, in
particular, an outer
cartridge or an external peripheral lateral surface. Said surface itself in
turn can be designed so
that it has a cross section that is, for example, round, oval or else angular,
in particular polygonal,
most particularly preferably rectangular or square.
Moreover it is preferable, in the context of the invention, for a flange to
extend, on the
outside, over the casing itself, wherein the flange can be formed as a pipe
component or also as a
fitting or else a elbow piece, and the flange has in particular a feed line or
discharge line for the
first medium. The radially peripheral channel according to the invention is
formed by a radially
outward oriented shaping of the flange, wherein the outward oriented shaping
is designed in
particular as a radial outward oriented curvature. Consequently, a hollow
space forms between
an inner side of the curvature and an outer lateral surface of the casing. The
feed line for the
second medium is then in turn connected to the flange. In particular, in the
area of the curvature,
a connecting piece is formed and/or a recess is formed which forms the feed
line for the channel
according to the invention. As a result, the second medium, in particular a
cooling medium, most
particularly preferably cooling water, is then led into the channel and it is
distributed radially
peripherally on the outside around the casing. The medium then passes through
openings in the
casing into the inner space of the heat exchanger or into the inner space of
the casing.
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In particular, the openings themselves are formed for this purpose by mutually
spaced
holes, wherein the holes in the casing are formed peripherally in the area of
the channel. Here it
is possible, in the context of the invention, to place the holes at equal
mutual spacings radially
peripherally to one another in the casing. Here it is conceivable, for
example, for the holes to first
have larger mutual spacings in the area of the feed line, wherein then, with
increasing distance
from the feed line in the flow direction of the channel, the mutual spacings
of the holes are
decreased. Here, for example, at first few holes are provided, so that, in the
area of the feed line,
in which a higher pressure and/or a higher flow rate of the second medium
exist(s), only a small
portion, relatively speaking, of the second medium enters the casing, and,
with increasing
distance from the feed line, due to a decrease in the spacings and thus an
increase in the number
of the holes, a sufficient portion of the second medium likewise enters the
inner space of the
casing, but with simultaneously decreasing pressure and/or decreasing flow
rate of the second
medium.
Moreover, in the context of the invention, it is provided that the holes have
mutually
differing opening cross sections, wherein the opening cross sections in
particular of mutually
separated openings, are formed so that they increase from the feed line on in
the flow direction of
the channel. Consequently, the openings in the area of the feed line have a
smaller opening cross
section than the openings at a distance from the feed line in the flow
direction. The size of the
opening cross section of each opening thus increases in the flow direction of
the channel. As a
result, it is possible again for the second medium to have a higher pressure
and/or a higher flow
rate in the area of the feed line, wherein the pressure and/or the flow rate
decreases in the flow
direction of the channel, so as to convey sufficient medium from the channel
into the inner space
of the casing, resulting in a homogeneous inflow radially peripherally into
the casing.
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Moreover, in the context of the invention it is possible for the cross-
sectional area of the
channel to be of different design; in particular the cross-sectional area of
the feed line decreases
in the flow direction of the channel. Due to the decreasing cross-sectional
area, the decreasing
pressure of the second medium in the flow direction of the channel and/or the
decreasing flow
rate of the second medium is/are likewise counteracted. Due to the narrowing
of the cross-
sectional area, the pressure and/or the flow rate of the second medium in the
flow direction of the
channel is/are kept approximately constant or else increased, resulting in an
approximately
homogeneous flow pattern through the openings into the interior of the casing.
Moreover, it is preferable in the context of the invention for a baffle plate
to be arranged
in the casing in the flow direction of the first fluid after the openings in
the casing, wherein the
baffle plate is passed through by heat exchanger tubes, and the baffle plate
preferably has a
central cutout for the passage of the second medium in the longitudinal
direction of the casing.
The baffle plate itself first ensures that the second medium, consequently the
cooling
fluid, does not run or flow, after entry into the casing, directly both in the
radial and also in the
axial direction into the interior space of the casing, thus cooling the end
plate or the tube collar
only insufficiently. Thus, an accumulation of the second medium first occurs
in the area of the
end plate, so that the second medium in particular also cools the end plate
and the heat exchanger
tubes in its inflow area for the first medium. Then the second medium also
flows in the axial
direction, into the interior of the casing in particular through an opening or
else a cutout arranged
centrally in the baffle plate.
Moreover, an end plate is preferably arranged upstream of the openings in the
casing in
the flow direction of the first fluid through the casing, wherein the end
plate for the passage of
the first medium is passed through by the heat exchanger tubes. In the context
of the invention,
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the end plate is, in particular, a tube collar or else a tube sheet. The
latter, on the one hand, does
not have to be formed from a high-temperature resistant and thus cost
intensive material, and it
can also be formed so that, in terms of wall thickness and thus is in terms of
the overall material
use, it is thinner and smaller, as a result of which the production costs for
manufacturing due to
material cost are reduced. In the context of the invention it is also possible
for the coupling
between the heat exchanger tube and the end plate in the tube sheet, by
soldering, for example, to
be manufactured with greater tolerances, since the thermal distortion does not
affect the tightness
and thus the longevity aspects, due to the clearly improved cooling properties
in the area of the
end plate.
For the manufacture of the heat exchanger according to the invention, at least
one
bonding connection, in particular a soldering connection, most particularly
preferably a hard
soldering connection, is established between the flange and the casing, most
particularly
preferably between the outer side of the casing and the inner side of the
flange. However, in the
context of the invention, it is also possible to couple the two components,
the flange and the
casing, to one another by a welding connection or else by a gluing connection.
In particular, the
casing, but also the flange, can be produced from a metal material, for
example, from a steel
material, but preferably also from a light metal material. The soldering
process itself here allows
high degrees of freedom during the joining, since even materials that can
essentially not be
welded but can be soldered can be joined in a bonding and thus fluid tight
manner to one
another.
In particular, the channel is formed by two mutually spaced peripheral contact
surfaces,
between the flange and the outer side of the casing, wherein the contact
surfaces are thermally
joined to one another, in particular in a fluid tight manner. Consequently it
is possible to first
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produce the holes in the casing in the predetermined manner, then shift the
flange over the
casing, and thereafter establish the fluid-tight thermal joining of the two
components.
Additional advantages, features, properties and aspects of the present
invention are the
subject matter of the following description. Preferred embodiment variants are
represented in the
diagrammatic figures. They are used to facilitate understanding of the
invention.
Figures la and lb show a heat exchanger according to the invention in a
perspective
view and partial section view,
Figure 2 shows the operating principle of the manufacturing of the
peripheral
channel in a detailed section view,
Figure 3 shows a heat exchanger according to the invention in a section
view,
Figure 4 shows an end plate according to the invention, and
Figure 5 shows the end of a casing according to the invention.
In the figures, the same reference numerals are used for identical or similar
components,
even if a repeated description is omitted for reasons of simplification.
Figure la shows the heat exchanger 1 in a perspective view, comprising a
casing 2 as
well as a flange 3 which is slipped on to the casing 2 on the end side. The
flange 3 has an exhaust
gas line 4 for feeding a flowing exhaust gas A as well as a feed line 5 for
feeding a second
medium 6. The second medium 6 here reaches, through the feed line 5 itself, an
outer peripheral
channel 7, which is formed by means of an outward directed curvature 8 on the
flange 3 itself.
According to the invention, the external peripheral channel 7 has openings 9
toward the
casing 2, through which the respective medium 6 flows into a collection
chamber 12 represented
in Figure 3, and from said collection chamber it flows through a cutout 15
into the inner space of
the heat exchanger.
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Figure lb shows the heat exchanger 1 in a perspective partial section view.
Figure 2 shows the external peripheral channel 7 according to the invention in
a detailed
section view. The outward oriented curvature 8 on the flange 3 here forms the
external peripheral
channel 7 between casing 2 and flange 3. Into this channel 7, the second
medium 6 flows on the
outside, around the casing 2, and then, via openings 9 in the casing 2 itself,
enters the inner space
I of the casing 2. The medium is then separated from the feed side 10 of the
exhaust gas A by an
end plate 11.
Figure 3 then shows the further course of both the flowing exhaust gas A and
also of the
second medium 6 through the heat exchanger 1 according to the invention. The
second medium 6
accumulates via the external peripheral channel 7 first on the outside around
the casing 2, and
then flows into the inner space I of the casing 2 first into a collection
chamber 12. The collection
chamber 12, on the one hand, has a border formed by the end plate 11, wherein
the end plate 11
is passed through by the heat exchanger tubes 13, so that the flowing exhaust
gas A can flow
through the heat exchanger tubes 13. However, the collection chamber 12 is
furthermore sealed
off in the flow direction by a baffle plate 14, wherein the heat exchanger
tubes 13 are moreover
passed through the baffle plate 14. The baffle plate 14 itself has, in
particular, a central cutout 15
through which the second medium 6 can then flow out of the collection chamber
12 into the
inner space I of the casing 2.
Figure 4 shows the baffle plate 14 in a front view, wherein the individual
heat exchanger
tubes 13 or openings for the heat exchanger tubes 13 can be seen clearly, as
can the central
cutout 15.
Figure 5 shows a perspective view of a casing 2 according to the invention,
wherein no
flange 3 is slipped onto the casing 2. At the end of the casing 2, one can
clearly see radially
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. .
peripheral individual openings 9 at a mutual spacing a for the inflow of the
second fluid into the
collection chamber.
Furthermore, in Figure 2, in which the baffle plate 14 is not represented, one
can clearly
see that in each case a bonding coupling 16 is formed between casing 2, flange
3 and end plate
11.
In Figure 5, furthermore, the baffle plate 14 is arranged in the casing 2. A
medium can
thus flow through the openings 9 into the collection chamber 12 and from there
it can flow
through the cutout 15 into the inner space I.
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,
Reference numerals:
1 - Heat exchanger
2 - Casing
3 - Flange
4 - Exhaust gas line
- Feed line
6 - Second medium
7 - Channel
8 - Curvature
9 - Opening
- Inflow side
11 - End plate
12 - Collection chamber
13 - Heat exchanger tube
14 - Baffle plate
- Cutout
16¨ Bonding coupling
A - Exhaust gas
I - Inner space
a - Spacing
12
