U.S. patent application number 11/914305 was filed with the patent office on 2010-07-08 for exhaust gas system for a motor vehicle.
Invention is credited to David Herranz, Peter Kroner, Andreas Mayr, Marco Ranalli, Stefan Schmidt, Gregg Speer, Clive D. Telford, Helmut Venghaus, A. Steven Walleck, Lee Watts.
Application Number | 20100170229 11/914305 |
Document ID | / |
Family ID | 35708941 |
Filed Date | 2010-07-08 |
United States Patent
Application |
20100170229 |
Kind Code |
A1 |
Venghaus; Helmut ; et
al. |
July 8, 2010 |
EXHAUST GAS SYSTEM FOR A MOTOR VEHICLE
Abstract
An exhaust-gas system for a motor vehicle includes at least one
exhaust-gas cleaning system and at least one regeneration device
for the exhaust-gas cleaning system, by means of which regeneration
device an oxidizable fluid in vapor form can be introduced into the
exhaust-gas stream ahead of the exhaust-gas cleaning system. The
regeneration device includes a housing with a chamber formed in it
as well as a heating element positioned in the chamber, the housing
having on its upstream side an inflow opening for exhaust gases and
on its downstream side an outlet opening and being arranged in the
interior of the exhaust-gas stream.
Inventors: |
Venghaus; Helmut;
(Ingolstadt, DE) ; Mayr; Andreas; (Meitingen,
DE) ; Ranalli; Marco; (Augsburg, DE) ; Kroner;
Peter; (Zweibruecken, DE) ; Speer; Gregg;
(Columbus, IN) ; Schmidt; Stefan; (Langweid/Lech,
DE) ; Watts; Lee; (Gersthofen, DE) ; Telford;
Clive D.; (Lancaster, GB) ; Herranz; David;
(Pamplona, ES) ; Walleck; A. Steven; (Lakewood,
OH) |
Correspondence
Address: |
BARNES & THORNBURG LLP
11 SOUTH MERIDIAN
INDIANAPOLIS
IN
46204
US
|
Family ID: |
35708941 |
Appl. No.: |
11/914305 |
Filed: |
December 29, 2005 |
PCT Filed: |
December 29, 2005 |
PCT NO: |
PCT/EP2005/014114 |
371 Date: |
November 3, 2009 |
Current U.S.
Class: |
60/295 ;
60/297 |
Current CPC
Class: |
B01D 2258/012 20130101;
B01D 53/90 20130101; F01N 2610/102 20130101; F01N 3/0253 20130101;
B01D 53/9431 20130101; F01N 2610/03 20130101; F01N 2610/10
20130101 |
Class at
Publication: |
60/295 ;
60/297 |
International
Class: |
F01N 3/023 20060101
F01N003/023; F01N 3/035 20060101 F01N003/035 |
Foreign Application Data
Date |
Code |
Application Number |
May 20, 2005 |
DE |
10 2005 023 398.8 |
Claims
1-7. (canceled)
8. An exhaust-gas system for a motor vehicle, comprising: at least
one exhaust-gas cleaning system, and at least one regeneration
device for the exhaust-gas cleaning system, the regeneration device
being configured to introduce an oxidizable fluid in vapor form
into the exhaust-gas stream ahead of the exhaust-gas cleaning
system, wherein (i) the regeneration device comprises a housing
with a chamber formed therein and a heating element positioned in
the chamber, (ii) the housing has, on its upstream side, an inflow
opening for exhaust gases and on its downstream side an outlet
opening, (iii) the housing is arranged in the motor vehicle's
exhaust-gas stream, and (iv) the housing has an essentially tubular
shape with a tapered upstream end.
9. The exhaust-gas system according to claim 8, wherein the heating
element comprises a porous foam.
10. The exhaust-gas system according to claim 9, wherein the foam
is a ceramic foam.
11. The exhaust-gas system according to claim 9, wherein the foam
is a metallic foam.
12. The exhaust-gas system according to claim 8, wherein the fluid
is a fuel.
13. The exhaust-gas system according to claim 8, wherein the
exhaust-gas cleaning system is a diesel particle filter.
14. The exhaust-gas system according to claim 8, wherein the
exhaust-gas cleaning system is a NO.sub.x-storage catalytic
converter.
Description
[0001] The invention relates to an exhaust-gas system for a motor
vehicle, comprising at least one exhaust-gas cleaning system and at
least one regeneration device for the exhaust-gas cleaning system,
by means of which regeneration device an oxidizable fluid can be
introduced into the exhaust-gas stream ahead of the exhaust-gas
cleaning system, the regeneration device comprising a housing with
a chamber formed in it as well as a heating element positioned in
the chamber. Exhaust-gas cleaning systems in the sense of the
invention may include, in particular, diesel particle filters and
NO.sub.x-storage catalytic converters.
[0002] In order to observe environmental guidelines it is required
to clean the exhaust-gases of vehicles which are driven by an
internal combustion engine. For example, suitable particle filters
are employed for reducing the particle-shaped emissions of diesel
motor vehicles. Such particle filters have to be regenerated from
time to time through burning off the particles which have
accumulated on the filter surface. To this end, an oxidation-based
catalytic converter is usually arranged upstream of the diesel
particle filter, which through oxidation of an oxidizable substance
in the exhaust-gas stream produces the heat which is needed for
burning off the diesel soot particles.
[0003] Furthermore, NO.sub.x-storage catalytic converters are
increasingly used, which serve for reducing the nitric-oxide
emission. For regenerating such storage catalytic converters it is
required to enrich the exhaust-gas. For this, special measures are
required in particular in the case of diesel engines which run with
an excess of air and whose exhaust-gas likewise has an air
surplus.
[0004] Thus, for regenerating a diesel particle filter or
NO.sub.x-storage catalytic converter in the exhaust-gas system of a
lean-combustion engine it is required from time to time to enrich
the exhaust-gas with an oxidizable substance. To this end, systems
are known which use an additional high pressure fuel injection
valve which is arranged in the manifold region of the exhaust-gas
system and injects fuel directly into the exhaust-gas stream. These
systems have the disadvantage, however, that a sufficient mixing of
the liquid fuel with the exhaust-gas is not always guaranteed.
[0005] Moreover, mechanisms are known (see e.g. EP 1 369 557 A1) in
which a defined amount of fuel is introduced into the heating
chamber of a vaporizer which is arranged outside the exhaust-gas
stream, where the fuel is vaporized and subsequently is introduced
into the exhaust-gas stream. For vaporizing the liquid fuel an
electrical glow plug is used in most cases, which has a comparably
high energy consumption.
[0006] In contrast to this, the invention provides an exhaust-gas
system with a regeneration device which compared to the systems
known from prior art provides for a more uniform distribution of
the oxidizable fluid and at the same time needs a smaller amount of
electric energy.
[0007] According to the invention, in an exhaust-gas system of the
type initially mentioned provision is made that the housing has on
its upstream side an inflow opening for exhaust gases and on its
downstream side an outlet opening and is arranged in the interior
of the exhaust-gas stream. Thus, the exhaust-gas system according
to the invention possesses a regeneration device which is arranged
within an exhaust-gas carrying tube and through which a part of the
exhaust-gas flows. Provided in the housing and upstream of the
heating element is an injection nozzle for the oxidizable fluid,
which sprays the fluid in the direction of the exhaust-gas stream
onto the heating element. The arrangement of the regeneration
device in the interior of the exhaust-gas stream offers the
advantage here that the heating element is heated not only by
electric energy, but in addition by the exhaust-gases flowing
through the chamber of the regeneration device. Thereby the energy
is reduced which is required for vaporizing the fluid. In addition,
the exhaust-gases flowing through the housing help to transport the
fluid through the heating element. Compared with an arrangement of
a heating element with an upstream fluid injection nozzle directly
in the exhaust-gas carrying tube, i.e. without a housing which
surrounds the regeneration device, the configuration according to
the invention is distinguished in that a more complete vaporization
is achieved in the chamber by the protecting housing.
[0008] The housing preferably has an essentially tubular shape with
a tapered upstream end. In this way it is achieved that merely a
small part of the available exhaust-gas flows through the housing,
which furthermore has a comparably small resistance to flow. What
is more, due to the continuous widening of the housing in the
direction of flow of the exhaust-gas, with such widening existing
at least in a first portion of the housing, the flow velocity of
the gas in the interior of the housing is diminished. Thereby the
dwell time of the exhaust-gas in the chamber will be increased,
likewise resulting in a more complete vaporization of the injected
fluid. Designing the downstream housing section as a cylindrical
tube with an essentially perpendicularly cut end provokes a
turbulent flow in the region of the outlet opening, whereby a
particularly effective mixing of the enriched gas from the
regeneration device with the remaining exhaust-gas stream is
ensured.
[0009] The heating element advantageously includes a porous foam.
The latter has a particularly high surface area which is effective
for vaporization, allowing a high heat transfer from the heating
element to the fluid which is to be vaporized. Also the dwell time
of the fluid in the region of the heating element will be
correspondingly increased.
[0010] The foam may be a ceramic foam or a metallic foam. For
heating, the latter may be wrapped by heating wires or interspersed
with these, but it is also possible to apply a voltage directly to
the porous material.
[0011] An additional fluid supply in the vehicle can be dispensed
with, if the fluid is a fuel.
[0012] Further features and advantages of the invention will be
apparent from the following description with the aid of the
attached drawing in which:
[0013] FIG. 1 shows a schematic partial view of an exhaust-gas
system according to the invention; and
[0014] FIG. 2 is an enlarged illustration of a regeneration device,
as it is used in the exhaust-gas system of FIG. 1.
[0015] FIG. 1 shows a section of an exhaust-gas system 10 which is
arranged downstream of a diesel engine of a motor vehicle (not
shown). The exhaust-gas system 10 has a first tube section 14 which
can be coupled to a manifold through a flange 12 as well as an
exhaust-gas cleaning system 16 in the form of a diesel particle
filter with an upstream or integrated oxidation-based catalytic
converter or in the form of a NO.sub.x-storage catalytic converter.
The exhaust-gas cleaning system 16 is connected through a second
tube section 18 with an end portion (not shown) of the exhaust-gas
system 10. Of course, the exhaust-gas system according to the
invention may have further exhaust-gas cleaning elements, for
instance an oxidation-based catalytic converter which is arranged
near the engine, or, in the case of a combination of NO.sub.x- and
particle reduction, a SCR-catalytic converter.
[0016] For regenerating the exhaust-gas cleaning system 16, a
regeneration device 20 is provided which is arranged in the
interior of the first tube section 14 immediately upstream of the
exhaust-gas cleaning system 16. The regeneration device 20
comprises an essentially tubular housing 22 which at its upstream
side is conically tapered and has a small inflow opening 24 for
exhaust gases (see FIG. 2). At the downstream side of the housing
22, an outlet opening 26 is provided which extends across almost
the entire end face of the housing 22.
[0017] A chamber 28 is formed in the interior of the housing 22; an
injection nozzle 30 for fuel extends into this chamber. The
injection nozzle is connected with a fuel line of the motor vehicle
through a (not shown) fuel pump or metering device. The downstream
part of the chamber 28 is almost completely occupied by a heating
element 32 which is a porous ceramic foam or metallic foam. For the
purpose of heating, this foam is wrapped by a current-carrying wire
or interspersed by it, or a voltage is applied to the (electrically
conductive) foam itself. As an alternative, also a plate-shaped
honeycomb-like ceramic structure may be provided as the heating
element 32, which structure has the shape of the internal diameter
of the housing 22. The important point in the selection of the
heating element 32 is merely that it has a structure which is
distinguished by an as large a surface area as possible and which
offers the gas, which flows through it, a certain resistance which
is not excessively high.
[0018] For initiating the regeneration, some fuel is injected
through the injection nozzle 30 into the chamber 28 towards the
heating element 32. This fuel impinges on the heating element 32
which has a particularly high surface area for vaporizing the fuel,
and becomes vaporized. At the same time, a part of the exhaust gas
(in FIG. 2 illustrated by arrows) flows through the inflow opening
24 into the chamber 28, through the pores or openings of the
heating element 32 and finally, entraining the fuel which now is in
the vapor state, through the outlet opening 26 out of the housing
22. Thus, a part of the exhaust-gas is used to transport the
injected fuel through the heating element 32. Further, the thermal
energy of the exhaust-gas which flows through the chamber 28 is
used for additionally heating the heating element, whereby the
electric energy which is needed for vaporizing the fuel can be
advantageously lowered. Thus, electrically produced thermal energy
as well as the thermal energy of the exhaust-gas is used for
initiating the regeneration of the exhaust-gas cleaning system
16.
[0019] In consequence of the special shape of the housing 22 with
the chamber 28 which initially widens in the direction of flow, the
flow velocity of the exhaust-gas reduces in the interior of the
chamber 28. In this way a longer dwell time of the exhaust-gas in
the chamber 28 is achieved, whereby a complete vaporizing of the
supplied fuel is ensured. In addition, the shape of the housing 22
and its arrangement parallel to the outer wall of the first tube
section 14 provides for a particularly good mixing of the
exhaust-gas, coming from the chamber 28 and enriched with fuel,
with the exhaust gas which flows past the housing 22 outside the
latter. It is in particular the design of the tubular housing 22 in
the region of the outlet opening 26 with the abrupt end which
provides for strong turbulences downstream of the housing 22
(indicated by the eddies in FIG. 2), which allow an optimum
distribution of the supplied fuel. The difference in pressure
between the gas flows due to the differing flow velocities in the
interior of the chamber 28 and outside the housing also makes a
contribution to this.
* * * * *