Title of Invention

EXHAUST SYSTEM HAVING AN EXHAUST GAS TREATMENT UNIT AND A HEAT EXCHANGER IN AN EXHAUST RECYCLE LINE

Abstract The invention relates to exhaust system (1) on an internal combustion engine (2), comprising an inlet system (3) and an exhaust outlet (4), whereby the exhaust outlet (4) and the inlet system(3) are connected by means of an exhaust recycle line (5) in which an exhaust treatment unit (6) and a heat exchanger (7) are embodied. The heat exchanger (7) has a first back pressure and the exhaust treatment unit (6) has a second back pressure smaller than the first back pressure, characterised in that the exhaust treatment unit (6) is embodied at such a first separation (8) from the heat exchanger (7) in the direction of flow that, during operation, a gas flow (14) entering the exhaust treatment unit (6) is equilibrated. Said exhaust system permits an advantageous embodiment of a heat exchanger (7) and an exhaust treatment un it (6), such as for example a honeycomb body in the exhaust recycle line (5), whereby both the heat exchanger (7) and the exhaust treatment unit (6) can have a smaller embodiment than in conventional system. The above reduces the costs considerably on equipping such a system.
Full Text WO 2006/100090 PCT/EP2006/002702
- 1 -
Exhaust system having an exhaust gas treatment unit and
a heat exchanger in an exhaust gas recirculation line
The subject matter of the present invention is an
exhaust system for internal combustion engines having a
heat exchanger and an exhaust gas treatment unit in an
exhaust gas recirculation line.
Exhaust systems of internal combustion engine are often
formed with heat exchangers which are used to cool the
exhaust gas, in particular when the exhaust gas is
recirculated into the air inlet region of the internal
combustion engine. Contamination of the heat exchanger
by pollutants present in the exhaust gas reduces its
effectiveness so that when the heat exchanger is
configured it has to be basically overdimensioned in
order to ensure that the heat exchanger has at least
the reference effectiveness over a relatively long time
period.
In order to reduce the contamination of the heat
exchanger, it is known from the prior art to form a
catalytic converter upstream of the heat exchanger by
means of which at least long-chained hydrocarbons,
which can lead to sticky deposits in the heat
exchanger, are removed. Such systems have the
disadvantage that either insufficient conversion of the
exhaust gas occurs due to the catalytic converter being
arranged upstream, so that contamination of the heat
exchanger still occurs, or that the catalytic converter
has to be given very large dimensions in order to
effectively prevent the contamination of the heat
exchanger.
Taking this as a starting point, the invention is based
on the object of proposing a system which is to be used

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in the exhaust gas recirculation line and which
comprises a heat exchanger and a catalytic converter in
which effective reduction of the contamination of the
heat exchanger and at the same time a smallest possible
overall volume of the heat exchanger and of the
catalytic converter are obtained.
This object is achieved by means of an exhaust system
having the features of claim 1. Advantageous
developments are the subject matter of the dependent
claims.
The inventive exhaust system of an internal combustion
engine which comprises an intake system and an exhaust
outlet, wherein the exhaust outlet and intake system
are connected via an exhaust gas recirculation line in
which an exhaust gas treatment unit and a heat
exchanger are formed, wherein the heat exchanger has a
first backpressure and the exhaust gas treatment unit
has a second backpressure which is lower than the first
backpressure, is defined by the fact that the exhaust
gas treatment unit is formed at such a first distance
upstream of the heat exchanger in the direction of flow
that during operation a gas flow which enters the
exhaust gas treatment unit is homogenized. This means
in particular that the backpressure upstream of the
exhaust gas treatment unit in the direction of flow is
influenced by the first backpressure of the heat
exchanger.

The heat exchanger is to be understood here in
particular also as referring to an exhaust cooler with
which the fed-back exhaust gas is cooled. The internal
combustion engine is, in particular a diesel engine,
for example a diesel engine of a motor vehicle (for
example of a passenger car, of a lorry, of an engine-
operated two wheeled vehicle, boat or aircraft) or a

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diesel engine in a stationary application.
Homogenization is also to be understood in particular
as referring to widening of the probability
distribution of the speeds which occur.
The design of the heat exchanger gives rise to the
raised backpressure compared to the exhaust gas
treatment unit. In particular, a heat exchanger which
has a plurality of pipes through which the exhaust gas
flows is advantageous. A cooling medium which flows
through the housing of the heat exchanger and is
extracted from a cooling circuit (not illustrated) of
the internal combustion engine preferably flows around
these pipes. In particular honeycomb bodies, for
example ceramic or metallic honeycomb bodies, or else
wire mesh bodies, bodies made of metal foam or the
like, are suitable as exhaust gas treatment units.
Metallic honeycomb bodies can be constructed, in
particular, from at least one at least partially
structured, metallic layer and, if appropriate, at
least one essentially smooth layer which are wound or
stacked and twisted together. The layers which are
twisted or wound together form cavities through which a
fluid can flow and which are bounded by the layers. The
layers are in particular formed from a material which
is resistant to high temperature corrosion, such as Al
or Cr steel. The layers can be connected to one
another, in particular in a materially joined fashion,
such as for example by means of a high temperature
soldering method. Both the layers which are essentially
smooth and the at least partially structured layers can
have, at least in certain areas, microstructures,
baffle faces, breakthroughs and/or perforations which
promote the mixing of the gas flow even further.
The homogenization of the gas flow before it enters the
exhaust gas treatment unit advantageous occurs by

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virtue of the fact that the exhaust gas treatment unit
is formed relatively close upstream of the heat
exchanger. This leads to homogenization of the gas flow
already in the exhaust gas treatment unit so that here
the conversion rate is improved since exhaust gas is
applied more uniformly to the cross section of the
exhaust gas treatment unit. The volume of the exhaust
gas treatment unit can thus be reduced compared to a
customary design with the same conversion rate of the
pollutants in the exhaust gas. The significantly more
efficient conversion rate of the pollutants also
reduces the contamination of the heat exchanger so that
it can also be given smaller dimensions compared to
conventional heat exchangers.
In order to form an exhaust gas treatment unit which
has only a low backpressure, it is possible to use a
honeycomb body which has a relatively low number of
cells, for example less than 400 cpsi (cells per square
inch), preferably less than 3 00 cpsi, particularly
preferably 200 cpsi and less, in particular even
100 cpsi.
According to one advantageous configuration of the
exhaust system according to the invention, the first
distance is selected such that the effect of the first
backpressure and of the second backpressure accumulate.
Accumulation is understood here in particular to refer
to the fact that backpressure which is present upstream
of the exhaust gas treatment unit is higher than the
second backpressure which the exhaust gas treatment
unit would have as such. The backpressure upstream of a
component in a flow brings about a type of pressure
cushion which causes the flow to change. In an extreme
case, the present invention brings about a situation in
which only one pressure cushion is formed in front of

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the exhaust gas treatment unit instead of two areas
with a pressure cushion, one in front of the heat
exchanger and one in front of the exhaust gas treatment
unit, respectively.
The accumulation of the backpressures advantageously
leads to a situation in which before the exhaust gas
flows into the exhaust gas treatment unit it has to
overcome a backpressure which is higher than the second
backpressure of the exhaust gas treatment unit.
Depending on the configuration of the heat exchanger
and of the exhaust gas treatment unit, the backpressure
is even significantly higher than the second
backpressure. Raising the backpressure brings about
homogenization of the flow of the exhaust gas treatment
unit, and thus of the gas flow through the exhaust gas
treatment unit and heat exchanger.
According to a further advantageous configuration,a
second distance of a gas inlet end side of the exhaust
gas treatment unit from a gas inlet end side of the
heat exchanger is less than 60 mm, preferably less than
45 mm, particularly less than 30 mm.
These values have proven particularly advantageous. In
particular, under customary operating conditions the
effects of the first and of the second backpressure
accumulate.
According to a further advantageous configuration of
the exhaust system according to the invention, the
extent of the exhaust gas treatment unit in the
direction of flow is less than 100 mm, preferably less
than 50 mm, particularly preferably 25 mm or less.
Owing to the very homogenous and effective conversion
of the corresponding substances in the exhaust gas, in

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particular of hydrocarbons, relatively small exhaust
gas treatment units can be used.
According to a further advantageous configuration of
the exhaust system according to the invention, the
exhaust gas treatment unit comprises a honeycomb body.
With a honeycomb body it is possible to provide an
exhaust gas treatment unit whose properties, such as
surface, backpressure etc., can be set very precisely.
In particular metallic or ceramic honeycomb bodies are
suitable as honeycomb bodies. In particular, honeycomb
bodies such as are described, for example in DE 197 55
703 A1, WO 90/13736 A1 and WO 99/11911 A1 can
advantageously be used. Reference is made to the entire
contents of these applications with respect to the
attachment of the honeycomb body.
According to a further advantageous configuration of
the exhaust system according to the invention, the
first distance between the exhaust gas treatment unit
and the heat exchanger is less than 15 mm, preferably
less than 10 mm, particularly less than 5 mm.
In particular it is also advantageous to provide the
heat exchanger and exhaust gas treatment unit in a
common housing. In this context, the exhaust gas
treatment unit can be held in a corresponding bead of
the housing by means of beading or the like. It is also
possible to fit the exhaust gas treatment unit flush
onto an end side of the heat exchanger.
According to a further advantageous configuration of
the exhaust system according to the invention, the
exhaust gas treatment unit comprises a catalytically
active coating, in particular an oxidation catalyst
coating.

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The catalytically active coating comprises, for
example, a ceramic wash coat which contains materials
which catalyze the desired reactions, that is to say in
particular reduce the reaction temperature of these
reactions to such an extent that they occur to an
appreciable extent at the temperatures in the exhaust
gas recirculation line. In particular noble metals such
as platinum, rhodium or the like are suitable as
catalytic converters. The oxidation catalyst coating
catalyzes, in particular, the oxidation of hydrocarbons
since they are also responsible for the contamination
of the heat exchanger. The hydrocarbons form a sticky
substance which condenses on the cold areas of the heat
exchanger and which can also cause soot particles
contained in the exhaust gas to stick to the walls of
the heat exchanger. The oxidation of hydrocarbons
therefore leads in a particularly advantageous way to a
significant reduction in the contamination of the heat
exchanger. In particular in exhaust systems of diesel
engines, very wide ranging up to complete oxidation of
the hydrocarbons occurs owing to the relatively high
proportion of oxygen in the exhaust gas.
In order to achieve the maximum possible conversion
efficiency of the oxidation of the hydrocarbons, the
exhaust gas treatment unit is in particular formed in
such a way that the dwell time is as long as possible
and the surface available for the reaction is as large
as possible.
According to a further advantageous configuration of
the exhaust system according to the invention, the
ratio of the first backpressure to the second
backpressure is greater than 2, preferably greater than
10.

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In particular under these backpressure conditions, that
is to say when the backpressure of the heat exchanger
as such is greater than the backpressure of the exhaust
gas treatment unit as such by a factor of 2 or even 10,
the effects of the first backpressure of the heat
exchanger and of the second backpressure of the exhaust
gas treatment unit accumulate in a particularly
advantageous way, even at first distances of 15 mm or
less.
The present invention will be explained in more detail
with reference to the appended figures, without said
invention being restricted to the exemplary embodiments
and advantages shown as described there. In the
drawings:
figure 1 is a schematic view of a first exemplary
embodiment of an exhaust system according to
the invention;
figure 2 is a schematic view of a detail of the first
exemplary embodiment of an exhaust system
according to the invention;
figure 3 is a schematic view of a detail of a second
exemplary embodiment of an exhaust system
according to the invention; and
figure 4 is a schematic view of two probability
distributions of a the flow speed.
Figure 1 is a schematic view of a first exemplary
embodiment of an inventive exhaust system 1 of an
internal combustion engine 2. The internal combustion
engine 2 comprises an intake system 3 and an exhaust
outlet 4, when the exhaust outlet 4 and intake system 3
are connected via an exhaust gas recirculation line 5

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in which an exhaust gas treatment unit 6 and a heat
exchanger 7 are formed. The heat exchanger 7 has a
first backpressure, and the exhaust gas treatment unit
6 has a second backpressure which is lower than the
first backpressure. The customary direction of flow of
the exhaust gas has been symbolized by corresponding
arrows. The quantity of exhaust gas which flows through
the exhaust gas recirculation line 5 can be regulated,
for example by means of corresponding valves (not
shown) . The exhaust gas recirculation line 5 can branch
off on the exhaust gas side, either upstream or
downstream of an exhaust gas turbocharger (not shown).
According to the invention, the exhaust gas treatment
unit 6 is formed at such a first distance 8 upstream of
the heat exchanger 7 in the direction of flow that
during operation a gas flow 14 which enters the exhaust
gas treatment unit 6 is homogenized. The first distance
8 is in particular less than 15 mm, preferably less
than 10 mm, particularly preferably less than 5 mm. The
heat exchanger 7 and exhaust gas treatment unit 6 are
embodied in such a way that at this first distance 8
the effects of the first backpressure and of the second
backpressure are accumulated so that the exhaust gas
flowing into the exhaust gas treatment unit 6 has to
overcome a backpressure which is higher than the second
backpressure of the exhaust gas treatment unit 6 as
such. This leads to a situation, as explained above, in
which the gas flow 14 which flows into the exhaust gas
treatment unit 6 is homogenized.
Figure 2 is a schematic view of a detail of the exhaust
gas recirculation line 5, including the exhaust gas
treatment unit 6 and the heat exchanger 7. A second
distance 9 between a gas inlet end side 10 of the heat
exchanger 7 and a gas inlet end side 11 of the exhaust
gas treatment unit 6 is selected according to the

WO 2006/100090 PCT/EP2006/002702
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invention in such a way that the flow in the exhaust
gas treatment unit 6 is homogenized. In particular, the
second distance 9 is less than 60 mm, preferably less
than 45 mm, particularly less than 3 0 mm. In particular
short honeycomb bodies, in particular with an extent 12
in the direction of flow of approximately 20 to 40 mm,
can be used as the exhaust gas treatment unit 6. The
first distance 8 is, for example, less than 15 mm or
else 5 mm or less. In particular, the first distance 8
is selected such that the effect of the first
backpressure of the heat exchanger 7 and of the second
backpressure of the exhaust gas treatment unit 6
accumulate so that the exhaust gas which flows into the
exhaust gas treatment unit 6 has to overcome a
backpressure which is higher, preferably significantly
higher, than the second backpressure of the exhaust gas
treatment unit 6.
Figure 3 is a schematic view of a detail of a further
exemplary embodiment of an exhaust system 1 according
to the invention. Here, a cone 13 which comprises the
exhaust treatment unit 6 which is embodied as a
honeycomb body 17 with passages 18 which are conical
here, is formed in the exhaust gas recirculation
line 5. The gas flow 14 which passes through the
exhaust gas recirculation line 5 is directed to the
heat exchanger 7 by the cone 13. The heat exchanger 7
comprises exhaust pipes 15 in a housing 16. The gas
flow 14 passes through the exhaust pipes 15, the
coolant which is part of the cooling circuit of the
internal combustion engine 2 flowing around said
exhaust pipes 15 in the housing 16. The first distance
8 between the heat exchanger 7 and the exhaust gas
treatment unit 6 is selected according to the invention
in such a way that during operation a gas flow 14 which
enters the exhaust gas treatment unit 6 is homogenized.

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Figure 4 is a schematic view of a first probability-
distribution 19 of the speed v and a second probability
distribution 20 of the speed v. The first probability
distribution 19 is obtained if gas flows only through
the exhaust gas treatment unit 6, that is to say
without a heat exchanger 7 being formed downstream of
said exhaust gas treatment unit 6 in the direction of
flow. The probability of a certain speed being present
in the gas is plotted for both distributions. Both the
probability and the speed are given in relative units.
The second probability distribution 20 is the
probability distribution in a system according to the
invention. It relates therefore to an exhaust system 1
with a heat exchanger 7 and an exhaust gas treatment
unit 6 in an exhaust gas recirculation line 5. The
second probability distribution 2 0 is wider, has in
particular a greater width with half the maximum height
(full width half maximum) than the first probability
distribution 19. This is due to the inventive
homogenization of the flow.
The exhaust system according to the invention
advantageously permits a heat exchanger 7 and an
exhaust gas treatment unit 6, such as for example a
honeycomb body, to be formed in the exhaust gas
recirculation line 5, and at the same time both the
heat exchanger 7 and the exhaust gas treatment unit 6
can be made smaller than is customary. This provides
considerable cost savings when configuring such
systems.

2006/100090 PCT/EP2006/002702
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List of reference numerals
exhaust system
internal combustion engine
intake system
exhaust outlet
exhaust gas recirculation line
exhaust gas treatment unit
heat exchanger
first distance
second distance
gas inlet end side of the heat exchanger
gas inlet end side of the exhaust gas treatment
unit
extent
cone
gas flow
exhaust pipe
housing
honeycomb body
passage
first probability distribution
second probability distribution

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Patent Claims
1. An exhaust system (1) of an internal combustion
engine (2), which comprises an intake system (3) and an
exhaust outlet (4) , wherein the exhaust outlet (4) and
the intake system (3) are connected via an exhaust gas
recirculation line (5) in which an exhaust gas
treatment unit (6) and a heat exchanger (7) are formed,
wherein the heat exchanger (7) has a first backpressure
and the exhaust gas treatment unit (6) has a second
backpressure which is lower than the first
backpressure, characterized in that the exhaust gas
treatment unit (6) is formed at such a first distance
(8) upstream of the heat exchanger (7) in the direction
of flow that during operation a gas flow (14) which
enters the exhaust gas treatment unit (6) is
homogenized.
2. The exhaust system (1) as claimed in claim 1, in
which the first distance (8) is selected such that the
effect of the first backpressure and of the second
backpressure accumulate.
3. The exhaust system (1) as claimed in claim 1 or 2,
in which a second distance (9) of a gas inlet end side
(11) of the exhaust gas treatment unit (6) from a gas
inlet end side (10) of heat exchanger (7) is less than
60 mm, preferably less than 45 mm, particularly
preferably less than 3 0 mm.
4. The exhaust system (1) as claimed in one of the
preceding claims, in which the extent (12) of the
exhaust gas treatment unit (6) in the direction of flow
is less than 100 mm, preferably less than 50 mm,
particularly preferably 25 mm or less.

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5. The exhaust system (1) as claimed in one of the
preceding claims, in which the first distance (8)
between the exhaust gas treatment unit (6) and the heat
exchanger (7) is less than 15 mm, preferably less than
10 mm, particularly preferably less than 5 mm.
6. The exhaust system (1) as claimed in one of the
preceding claims, in which the exhaust gas treatment
unit (6) comprises a honeycomb body (17).
7. The exhaust system (1) as claimed in one of the
preceding claims, in which the exhaust gas treatment
unit (6) comprises a catalytically active coating, in
particular an oxidation catalyst coating.
8. The exhaust system (1) as claimed in one of the
preceding claims, in which the ratio of the first
backpressure to the second backpressure is greater than
2, preferably greater than 10.

The invention relates to exhaust system (1) on an internal combustion engine
(2), comprising an inlet system (3) and an exhaust outlet (4), whereby the
exhaust outlet (4) and the inlet system(3) are connected by means of an exhaust
recycle line (5) in which an exhaust treatment unit (6) and a heat exchanger (7)
are embodied. The heat exchanger (7) has a first back pressure and the exhaust
treatment unit (6) has a second back pressure smaller than the first back
pressure, characterised in that the exhaust treatment unit (6) is embodied at
such a first separation (8) from the heat exchanger (7) in the direction of flow
that, during operation, a gas flow (14) entering the exhaust treatment unit (6) is
equilibrated. Said exhaust system permits an advantageous embodiment of a
heat exchanger (7) and an exhaust treatment un it (6), such as for example a
honeycomb body in the exhaust recycle line (5), whereby both the heat
exchanger (7) and the exhaust treatment unit (6) can have a smaller
embodiment than in conventional system. The above reduces the costs
considerably on equipping such a system.

Documents:

03518-kolnp-2007-abstract.pdf

03518-kolnp-2007-claims.pdf

03518-kolnp-2007-correspondence others 1.1.pdf

03518-kolnp-2007-correspondence others.pdf

03518-kolnp-2007-description complete.pdf

03518-kolnp-2007-drawings.pdf

03518-kolnp-2007-form 1.pdf

03518-kolnp-2007-form 18.pdf

03518-kolnp-2007-form 2.pdf

03518-kolnp-2007-form 3.pdf

03518-kolnp-2007-form 5.pdf

03518-kolnp-2007-gpa.pdf

03518-kolnp-2007-international publication.pdf

03518-kolnp-2007-international search report.pdf

03518-kolnp-2007-others pct form.pdf

03518-kolnp-2007-pct request form.pdf

03518-kolnp-2007-translated copy of priority document.pdf

3518-KOLNP-2007-CLAIMS-1.1.pdf

3518-KOLNP-2007-CORRESPONDENCE OTHERS 1.2.pdf

3518-KOLNP-2007-CORRESPONDENCE-1.3.pdf

3518-KOLNP-2007-CORRESPONDENCE-1.4.pdf

3518-KOLNP-2007-FORM 26.pdf

3518-KOLNP-2007-FORM 27.pdf

3518-KOLNP-2007-FORM-27.pdf

3518-KOLNP-2007-OTHERS-1.1.pdf

3518-KOLNP-2007-OTHERS.pdf

3518-KOLNP-2007-PETITION UNDER RULE 137.pdf

3518-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf

3518-KOLNP-2007-TRANSLATED COPY OF PRIORITY DOCUMENT 1.1.pdf

abstract-03518-kolnp-2007.jpg


Patent Number 239268
Indian Patent Application Number 3518/KOLNP/2007
PG Journal Number 12/2010
Publication Date 19-Mar-2010
Grant Date 15-Mar-2010
Date of Filing 19-Sep-2007
Name of Patentee EMITEC GESELLSCHAFT FUR EMISSIONS-TECHNOLOGIE MBH
Applicant Address HAUPTSTRASSE 128, 53797 LOHMAR
Inventors:
# Inventor's Name Inventor's Address
1 GESKES, PETER THEODOR-ROTHSCHILD-STRASSE 72 73760 OSTFILDERN
2 RUCKWIED, JENS KAUFFMANNSTRASSE 1 70195 STUTTGART
3 BRUCK, ROLF FROBELSTRASSE 12, 51429 BERGISCH GLADBACH
4 MAUCHER, ULRICH FRIEDERICA-KOCHER-STRASSE 17 70825 KORNTAL-MUNCHINGEN
5 SCHEEDER, ANDREAS HAUPTSTRASSE 57 53721 SIEGBURG
6 GESKES, PETER THEODOR-ROTHSCHILD-STRASSE 72 73760 OSTFILDERN
7 RUCKWIED, JENS KAUFFMANNSTRASSE 1 70195 STUTTGART
8 BRUCK, ROLF FROBELSTRASSE 12, 51429 BERGISCH GLADBACH
9 MAUCHER, ULRICH FRIEDERICA-KOCHER-STRASSE 17 70825 KORNTAL-MUNCHINGEN
10 SCHEEDER, ANDREAS HAUPTSTRASSE 57 53721 SIEGBURG
PCT International Classification Number F02M 25/07,F01N 3/28
PCT International Application Number PCT/EP2006/002702
PCT International Filing date 2006-03-24
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10 2005 014 264.8 2005-03-24 Germany