U.S. patent application number 12/641351 was filed with the patent office on 2010-06-24 for exhaust gas treatment device.
Invention is credited to Martin Adldinger, Wolfgang Hahnl, Marco Ranalli.
Application Number | 20100154396 12/641351 |
Document ID | / |
Family ID | 42220845 |
Filed Date | 2010-06-24 |
United States Patent
Application |
20100154396 |
Kind Code |
A1 |
Hahnl; Wolfgang ; et
al. |
June 24, 2010 |
EXHAUST GAS TREATMENT DEVICE
Abstract
An exhaust gas treatment device, in particular for an internal
combustion engine, is fitted with a housing including an entrance
and an exit. At least one porous substrate is accommodated in the
housing and has an exhaust gas flowing through the substrate. The
porous substrate is arranged in the flow path from the entrance to
the exit. At least one thermoelectric generator is provided on the
housing.
Inventors: |
Hahnl; Wolfgang; (Grimma,
DE) ; Adldinger; Martin; (Holzheim, DE) ;
Ranalli; Marco; (Augsburg, DE) |
Correspondence
Address: |
PAMELA A. KACHUR
577 W Santee Drive
Greensburg
IN
47240
US
|
Family ID: |
42220845 |
Appl. No.: |
12/641351 |
Filed: |
December 18, 2009 |
Current U.S.
Class: |
60/320 ;
62/3.2 |
Current CPC
Class: |
F01N 2240/04 20130101;
F01N 2260/00 20130101; F01N 5/025 20130101; F01N 2260/022 20130101;
Y02T 10/12 20130101; Y02T 10/16 20130101 |
Class at
Publication: |
60/320 ;
62/3.2 |
International
Class: |
F01N 5/02 20060101
F01N005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 19, 2008 |
DE |
10 2008 063 861.7 |
Claims
1. An exhaust gas treatment device for an internal combustion
engine, comprising: a housing including an entrance and an exit; at
least one porous substrate accommodated in said housing wherein an
exhaust gas flows through said at least one porous substrate, and
wherein said at least one porous substrate is arranged in a flow
path from said entrance to said exit; and at least one
thermoelectric generator provided on said housing.
2. The exhaust gas treatment device according to claim 1, wherein
said at least one thermoelectric generator is applied on an outside
of said housing.
3. The exhaust gas treatment device according to claim 1, wherein
said exhaust gas flows against an inner wall of said housing.
4. The exhaust gas treatment device according to claim 1, wherein
said at least one porous substrate consists of at least one of a
metal foam, metal sponge, and a metallic hollow sphere
structure.
5. The exhaust gas treatment device according to claim 1, including
heat conducting fins provided on at least one of an inside and an
outside of said exhaust gas treatment device.
6. The exhaust gas treatment device according to claim 1, including
a cooling device for said thermoelectric generator.
7. The exhaust gas treatment device according to claim 6, wherein
said cooling device surrounds an outside of said thermoelectric
generator.
8. The exhaust gas treatment device according to claim 6, wherein
said cooling device includes at least one cooling duct having a
cooling medium flowing through said at least one cooling duct.
9. The exhaust gas treatment device according to claim 8, wherein
said cooling medium is air.
10. The exhaust gas treatment device according to claim 9, wherein
said cooling device includes at least one inlet having a supply
opening so that air from surroundings of said exhaust gas treatment
device flows through said supply opening into said cooling
device.
11. The exhaust gas treatment device according to claim 10, wherein
said at least one inlet widens in a vehicle driving direction
towards an open end.
12. The exhaust gas treatment device according to claim 11, wherein
said at least one inlet comprises a plurality of inlets arranged
one behind each other, said plurality of inlets widening in the
vehicle driving direction towards said open end.
Description
RELATED APPLICATION
[0001] This application claims priority to DE Application No. 10
2008 063 861.7, which was filed Dec. 19, 2008.
FIELD OF THE INVENTION
[0002] The present invention relates to an exhaust gas treatment
device, in particular for an internal combustion engine of a
vehicle.
BACKGROUND OF THE INVENTION
[0003] For the treatment, more particularly for the purification of
exhaust gases of internal combustion engines, e.g., diesel engines
of passenger automobiles, it is known to arrange porous,
gas-permeable substrates in a closed metallic housing in an exhaust
pipe so that the exhaust gas flows through the substrate.
[0004] Exhaust gas treatment devices of this type, which may
involve, for example, diesel particulate filters or catalytic
converters, such as, e.g., for NO.sub.x reduction, are inserted in
the exhaust pipe in such a way that all of the exhaust gas has to
flow through the exhaust gas treatment device. In the process, the
exhaust gas is forced to pass through the porous substrate which
has a filter effect and/or effects a catalytically activated
chemical reaction with a chemically active coating. An exhaust gas
treatment occurs here, e.g., by chemical conversion, by mechanical
deposition of particles carried along with the exhaust gas, e.g.,
soot particles, in the pores of the substrate, or a combination of
different methods.
[0005] It is known to bring the substrate into the shape of a
hollow body having one or more walls. The hollow body is arranged
in the housing such that the exhaust gas must always flow through
at least one wall of the hollow body to pass from an entrance of
the housing to an exit thereof.
[0006] The exhaust gas stream that flows through the housing has a
temperature of several hundred degrees Celsius.
[0007] It is the object of the invention to utilize the thermal
energy of the exhaust gas stream.
SUMMARY OF THE INVENTION
[0008] The exhaust gas treatment device, which in particular is
provided for an internal combustion engine, includes a housing with
an entrance and an exit. At least one porous substrate is
accommodated in the housing and has an exhaust gas flowing through
the substrate. The substrate is arranged in a flow path from the
entrance to the exit. Further, at least one thermoelectric
generator is arranged on the housing. Thermoelectric generators are
devices for converting thermal energy into electrical energy. They
include thermocouple elements which operate on the so-called
"Seebeck effect" and in which a thermoelectric voltage is generated
based on the specific pairing of materials used and the temperature
difference prevailing across the thermocouple element. In this way,
the thermal energy of the exhaust gas stream can be utilized to
generate electrical energy. In addition, a cooling effect on the
housing is produced, which results in, e.g., a reduction in the
differences in the thermal expansion between the housing and the
substrate.
[0009] The thermoelectric generators employed may be known
conventional thermoelectric generators.
[0010] The thermoelectric generator is preferably applied on an
outside of the housing to be able to utilize a major part of the
thermal energy given off by the exhaust gas stream to the housing.
Thermoelectric generators are advantageously used in the form of
sheets or strips and are preferably so flexible that they can be
well adjusted to the surface of the housing. It is possible to
cover essentially the entire outer surface of the housing with one
or more thermoelectric generators.
[0011] The thermoelectric generators may be fastened to the housing
in any suitable manner, such as, e.g., by soldering or brazing, it
being of advantage here if a direct, large-area connection having
good thermal conductivity exists between the thermoelectric
generator and the outer surface of the housing.
[0012] Exhaust gas treatment devices in which the exhaust gas flows
directly against an inner wall of the housing are advantageous to
the configuration because a direct heat transfer from the exhaust
gas to the housing, and thus a high yield of thermal energy, is
ensured. The housing is designed, for example, in the form of a
cylinder having connecting funnels applied at the entrance and at
the exit. The cylindrical section has a larger diameter than an
adjacent exhaust gas pipe. The inner wall is preferably the inner
side of the cylindrical peripheral wall, which can be provided with
a known, e.g. catalytically active, coating which has such a small
thickness that it is normally of no consequence with regard to the
heat conduction.
[0013] In one example, the substrates through which the exhaust gas
flows are supported in the housing without the interposition of a
support mat, as a result of which the housing is uninsulated from
the inside.
[0014] Possible geometries to be used for the hollow body include,
e.g., a pair of cone envelopes or truncated cone envelopes fitted
inversely into each other, four- or multi-sided pyramid envelopes
or truncated pyramid envelopes, or a pair of cylinder envelopes
arranged concentrically in relation to each other.
[0015] Such envelopes may be simply produced by reshaped
sheets.
[0016] In one example, the substrate consists of a metal foam,
metal sponge and/or a metallic hollow sphere structure, or a wire
mesh or wire knit. In contrast to ceramic substrates, which are
wrapped in an elastic support mat and are accommodated in the
housing, in the case of a body made of a porous metal substrate, in
particular a hollow body, no such thermally insulating material is
arranged on the inner wall of the housing, so that a high yield of
thermal energy is ensured. In contrast to ceramic substrates, this
special metal substrate has an inherent elasticity which allows a
press fit in the housing, in particular without additional
fastening means.
[0017] In another known form, the substrate consists of one or more
porous ceramic blocks.
[0018] The difference in temperature necessary for operation of the
thermoelectric generator or generators is implemented in a radial
direction from an interior of the housing to the outside.
[0019] To increase the difference in temperature, heat conducting
fins may be provided on the inside and/or on the outside of the
exhaust gas treatment device, which preferably project radially
from the housing. Inside fins serve to withdraw as much heat as
possible from the exhaust gas stream to provide as high a
temperature as possible on the radially inner side of the
thermoelectric generator, whereas outside fins, preferably on the
thermoelectric generator, serve to radiate as much heat as possible
from the radially outer side of the thermoelectric generator to
cause the temperature there to be as low as possible.
[0020] The difference in temperature may be further increased by
making provision for a cooling device for the thermoelectric
generator.
[0021] The cooling device may consist of a cooling body, for
example, with cooling fins formed thereon, for instance, the
cooling body being placed on the outside of the thermoelectric
generator or generators.
[0022] In one example, the cooling device surrounds the
thermoelectric generator on the outside to dissipate heat to the
surroundings of the exhaust gas treatment device.
[0023] The cooling device may include at least one cooling duct
having a cooling medium flowing through the cooling duct. The
cooling duct or ducts is/are preferably formed between the
thermoelectric generator and a wall of the cooling device and may
extend in a longitudinal direction of the exhaust gas treatment
device.
[0024] It is also possible to employ a cooling liquid. In this
configuration, the cooling device may be connected to a
conventionally provided cooling circuit of the internal combustion
engine, for example.
[0025] It is, however, of advantage to use air as the cooling
medium since in this way the weight of the exhaust gas treatment
device may be reduced and the device may have a simpler
structure.
[0026] The cooling device includes, for example, at least one inlet
having a supply opening. Air from the surroundings of the exhaust
gas treatment device flows through the supply opening into the
cooling device. The inlet and the supply opening are preferably
provided in the immediate vicinity of the housing to produce an
effective air flow through the cooling device.
[0027] The inlet is advantageously oriented in a travel direction
of a vehicle in which the internal combustion engine is arranged
since in this way the relative wind can be made use of for
producing the air flow.
[0028] In one example, provision is made for at least one inlet
which widens in the travel direction towards the open end. A
plurality of inlets of any desired shape may be distributed both
over the periphery of the exhaust gas treatment device and over the
longitudinal extent thereof. For example, it is possible to make
provision for a plurality of inlets arranged one behind the other
and each widening in the travel direction towards the open end.
Here, the shape of the inlets may be selected such that a swirling
of the air in the cooling device is obtained, for example by curved
or obliquely extending walls, and that, where desired, outlets and
subsequent inlets may be provided in approximately the same plane.
This allows new cold cooling air flows to be supplied at all times
along the assembly made up of thermoelectric generators, so that
the cooling device is, as it were, subdivided into individual
cooling air ducts, and the cooling air is divided up into
individual cooling air flows.
[0029] These and other features of the present invention can be
best understood from the following specification and drawings, the
following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 shows a schematic longitudinal section taken through
an exhaust gas treatment device according to a first embodiment of
the invention;
[0031] FIG. 2 shows a schematic longitudinal section taken through
an exhaust gas treatment device according to a second embodiment of
the invention;
[0032] FIG. 3 shows a front view of the exhaust gas treatment
device according to the invention as shown in FIG. 2;
[0033] FIG. 4 shows a top view of the exhaust gas treatment device
according to the invention as shown in FIG. 2;
[0034] FIG. 5 shows a schematic longitudinal section taken through
an exhaust gas treatment device according to a third embodiment of
the invention;
[0035] FIG. 6 shows a front view of the exhaust gas treatment
device according to the invention as shown in FIG. 5;
[0036] FIG. 7 shows a schematic longitudinal section taken through
an exhaust gas treatment device according to a fourth embodiment of
the invention;
[0037] FIG. 8 shows a front view of the exhaust gas treatment
device according to the invention as shown in FIG. 7;
[0038] FIG. 9 shows a top view of the exhaust gas treatment device
according to the invention as shown in FIG. 7;
[0039] FIG. 10 shows a schematic longitudinal section taken through
an exhaust gas treatment device according to a fifth embodiment of
the invention;
[0040] FIG. 11 shows a top view of the exhaust gas treatment device
according to the invention as shown in FIG. 10;
[0041] FIG. 12 shows a front view of the exhaust gas treatment
device according to the invention as shown in FIG. 10; and
[0042] FIG. 13 shows a cross-section XIII-XIII taken through the
exhaust gas treatment device according to the invention as shown in
FIG. 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0043] FIG. 1 shows a first embodiment of an exhaust gas treatment
device 10, in particular for an internal combustion engine of a
vehicle, which includes a housing 12 having an entrance 14 and an
exit 16. A porous substrate 20 is accommodated in the housing 12
and has an exhaust gas 18 flowing through the substrate 20. The
substrate 20 is arranged in the flow path from the entrance 14 to
the exit 16. At least one thermoelectric generator 22 is provided
on the housing 12.
[0044] The exhaust gas treatment device 10 is, for example, a
catalytic converter for a motor vehicle, a particulate filter for a
motor vehicle, or a combination of a catalytic converter and a
particulate filter. Preferably, the porous substrate used consists
of a metal foam, a metal sponge and/or a metallic hollow sphere
structure, and has an inner and an outer contour in the shape of a
cone or a truncated cone.
[0045] Thermoelectric generators 22 utilize a difference in
temperature between two points of a conductor to generate an
electrical voltage. The structure and function of such generators
22 are known from the prior art and will not be discussed in
further detail. In each of the Figures, the thermoelectric
generator 22 is applied to the outside of the housing 12 and is
illustrated merely schematically and greatly simplified.
[0046] Furthermore, an active cooling device 24 is provided which
surrounds the thermoelectric generator 22 on the outside. The
cooling device 24 includes at least one cooling duct 26 through
which a cooling medium 28 flows. The cooling medium 28 is a liquid
or, preferably, air.
[0047] The housing 12 has a largely cylindrical shape with an oval
or polygonal base. In one example, the housing has a hexagonally
shaped base. The thermoelectric generator 22 makes use of the
temperature gradient that develops in a radial direction between
the housing 12 and the cooling device 24 to generate an electrical
voltage. The greater the temperature gradient between the housing
12 and the cooling device, the higher the electrical voltage
generated by the generator 22. In a preferred variant, the hot
exhaust gas 18 therefore flows directly against an inner side of
the housing wall to reach as high a housing temperature as
possible. The heat is absorbed especially well if the housing 12
has heat conducting fins 30 on the inside. Heat conducting fins 30
may also be provided on an outside of the housing 12 and/or on an
inside of the generator 22 to achieve a particularly efficient heat
transfer from the housing 12 to the inside of the generator 22. In
a similar fashion, the thermoelectric generator 22 may also be
provided with heat conducting fins 30 on its outside, which
protrude into the cooling duct 26 and ensure a particularly
efficient cooling of the outside of the generator 22.
[0048] Provision may also be made for a plurality of cooling ducts
26 spaced apart in the peripheral direction.
[0049] Further embodiments of the exhaust gas treatment device 10
are illustrated in FIGS. 2 to 13. Since there are no differences
from the first embodiment with regard to the design and functioning
in principle, reference is made in this respect to the above
description in relation to FIG. 1, and only the special features of
these exemplary embodiments will be discussed
[0050] FIG. 2 shows the exhaust gas treatment device 10 according
to a second embodiment, in which the cooling device 24 includes at
least one inlet 32 pointing in the travel direction and having a
supply opening 34, so that cooling medium 28, preferably air from
the surroundings of the exhaust gas treatment device 10, flows
through the supply opening 34 into the cooling device 24. According
to FIG. 2, the supply opening 34 is made to be very large to allow
a good air intake, with the inlet 32 tapering inwardly towards the
cooling duct 26. Since the inlet 32 is positioned in the region of
a conical housing neck 35, the inflow cross-section is extremely
large.
[0051] FIGS. 3 and 4 show the exhaust gas treatment device
according to FIG. 2 in a front view and a top view, respectively.
In this case, the housing 12 is of a cylindrical design with a
hexagonal base, with a flat thermoelectric generator 22 having heat
conducting fins 30 being fastened to each of the outer sides of the
side surfaces of the cylinder.
[0052] FIGS. 5 and 6 show a longitudinal section and a front view,
respectively, of the exhaust gas treatment device 10 according to a
third embodiment, which differs from the second embodiment merely
in that the inlet 32 of the cooling device 24 on a later bottom
surface of the exhaust gas treatment device 10 does not extend
beyond the cooling duct 26 in the radial direction. The inlet 32 is
not widened or is less widened in this region in order to enlarge
the supply opening 34, but is flattened (cf. FIG. 6) so as to
restrict as little as possible the ground clearance of the vehicle
in which the exhaust gas treatment device 10 is installed.
[0053] FIG. 7 shows a fourth embodiment of the exhaust gas
treatment device 10, in which the cooling device 24 includes a
plurality of inlets 32 arranged axially one behind the other in
relation to a longitudinal axis A. The inlets 32 here are each
formed such that they radially widen in the travel direction
towards the open end, i.e. towards the supply opening. FIGS. 8 and
9 illustrate the associated front view and top view of the exhaust
gas treatment device 10.
[0054] FIGS. 10 to 12 show a longitudinal section, a top view, and
a front view, respectively, of the exhaust gas treatment device 10
in accordance with a fifth embodiment, the cooling device of which
likewise includes a plurality of inlets 32, 32' arranged axially
one behind the other in relation to a longitudinal axis A. In this
embodiment the thermoelectric generator 22 is however subdivided
into two separate sections 36, 38, which are axially spaced apart
from each other and are arranged one behind the other. In relation
to the flow direction of the cooling medium 28, the cooling duct 26
has an undulating shape at the rear end of a front section 36.
[0055] At the front end of the rear section 38, the cooling duct 26
has a rear inlet 32', which is likewise of an undulating shape. The
front inlet 32 is rotated in relation to the rear inlet 32' in the
peripheral direction, so that a wave trough and a wave crest are
always disposed axially behind each other (cf. FIG. 12). This
allows cooling medium that has already been heated in the front
section 36 to flow out of the cooling duct 26 into the surroundings
between the sections 36, 38 of the thermoelectric generator 22 and
"fresh" cooling medium from the surroundings to flow into the
cooling duct 26 at the same time to cool the rear section 38 of the
generator 22. Since the efficiency of the thermoelectric generator
22 would be very low in this inflow and outflow region, the
generator 22 is recessed in this region, so that the axially
forward section 36 and the axially rearward section 38 are
produced.
[0056] FIG. 13 shows a cross-section XIII-XIII through the exhaust
gas treatment device according to FIG. 11, the section being taken
between the sections 36, 38 of the thermoelectric generator, and
with the exhaust gas and cooling medium flows being indicated by
arrows.
[0057] The exhaust gas 18 flows out radially through the substrate
20 at a high velocity and impinges as a turbulent flow onto the
housing 12, in particular onto the fins 30 of the housing 12. Due
to this turbulent flow, an especially good heat transfer is
effected between the exhaust gas 18 and the housing 12.
[0058] With respect to the flow of the cooling medium 28, FIG. 13
again illustrates that cooling medium 28 that has already been
heated in the front section 36 of the generator 22 can escape from
the cooling duct 26 between the sections 36, 38 of the generator 22
(dashed arrows) and, at the same time, fresh cooling medium 28 can
flow into the cooling duct 26.
[0059] In all of the embodiments, the hot exhaust gas flows
directly against the inner side of the housing 12.
[0060] No elastic support mat for supporting the substrate is
provided.
[0061] The substrate formed from the hollow metal spheres or the
metal sponge is radially elastic and may also be directly clamped
radially in the housing.
[0062] Also, the substrate need not necessarily be a hollow body,
but may a solid body.
[0063] According to the illustrated embodiments, the substrates are
fastened to a linkage or a holding mechanism in a region of their
axial ends, the holding mechanism, for its part, being fitted to
the housing.
[0064] Although an embodiment of this invention has been disclosed,
a worker of ordinary skill in this art would recognize that certain
modifications would come within the scope of this invention. For
that reason, the following claims should be studied to determine
the true scope and content of this invention.
* * * * *