U.S. patent application number 11/346037 was filed with the patent office on 2006-08-03 for internal combustion engine exhaust gas conveying device with internal lining, as well as process for production thereof.
This patent application is currently assigned to DaimlerChrysler AG. Invention is credited to Hartmut Baur, Erwin Loeffler, Johanna Musiol.
Application Number | 20060168938 11/346037 |
Document ID | / |
Family ID | 36709567 |
Filed Date | 2006-08-03 |
United States Patent
Application |
20060168938 |
Kind Code |
A1 |
Baur; Hartmut ; et
al. |
August 3, 2006 |
Internal combustion engine exhaust gas conveying device with
internal lining, as well as process for production thereof
Abstract
Exhaust gas conveying apparatus of an internal combustion engine
with internal liner in which the liner features capillary bores
which are open at least towards the exhaust gas conveying side of
the liner as well as process for the fabrication of said
apparatus.
Inventors: |
Baur; Hartmut; (Ertingen,
DE) ; Loeffler; Erwin; (Ulm, DE) ; Musiol;
Johanna; (Ulm, DE) |
Correspondence
Address: |
AKERMAN SENTERFITT
P.O. BOX 3188
WEST PALM BEACH
FL
33402-3188
US
|
Assignee: |
DaimlerChrysler AG
Stuttgart
DE
|
Family ID: |
36709567 |
Appl. No.: |
11/346037 |
Filed: |
February 2, 2006 |
Current U.S.
Class: |
60/272 ;
60/300 |
Current CPC
Class: |
F01N 2450/28 20130101;
F01N 3/0814 20130101; F01N 2330/18 20130101; F01N 3/0807 20130101;
F01N 2240/10 20130101; F01N 3/2807 20130101; F01N 13/143 20130101;
F01N 2330/04 20130101; F01N 3/0835 20130101; F01N 2370/24 20130101;
F01N 2330/02 20130101; B23K 2103/50 20180801; Y02T 10/12 20130101;
F01N 2450/22 20130101; F01N 13/102 20130101; F01N 2330/14 20130101;
F01N 2240/22 20130101; F01N 2330/06 20130101; F01N 2240/26
20130101; Y02T 10/26 20130101; F01N 3/2046 20130101; F01N 2240/18
20130101; B23K 2103/52 20180801; F01N 3/2006 20130101; B23K 26/40
20130101; F01N 2470/04 20130101; B23K 26/382 20151001; F01N 2570/12
20130101 |
Class at
Publication: |
060/272 ;
060/300 |
International
Class: |
F01N 7/14 20060101
F01N007/14; F01N 3/10 20060101 F01N003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 2, 2005 |
DE |
10 2005 004 651.7 |
Claims
1. An exhaust gas conveying apparatus of an internal combustion
engine with internal liner exposed on at least one side to conveyed
exhaust gas, wherein the liner features capillary bores which are
open at least towards the exhaust gas conveying side of the
liner.
2. An apparatus according to claim 1, wherein the liner features
capillary bores with different depths and/or different
diameters.
3. An apparatus according to claim 2, wherein the liner features
capillary bores with different depths and/or different diameters
such that it exhibits a gradient of its active surface.
4. An apparatus according to claim 1, wherein the liner features
capillary bores which are oriented generally perpendicular to the
exhaust gas conveying surface of the liner.
5. An apparatus according to claim 1, wherein the liner features
capillary bores which are inclined with respect to the exhaust gas
conveying surface of the liner.
6. An apparatus according to claim 1, wherein at least a partial
air gap remains between the outer wall of the liner and the
internal wall of the exhaust gas conveying apparatus.
7. An apparatus according to claim 1, wherein the apparatus is
located inside the exhaust gas tract of a motor vehicle.
8. An exhaust gas conveying exhaust manifold in a motor vehicle
with an internal liner exposed on at least one side to conveyed
exhaust gas, wherein the liner features capillary bores which are
open at least towards the exhaust gas conveying side of the
liner.
9. A process for the fabrication of an exhaust gas conveying
apparatus of an internal combustion engine with internal liner,
comprising: providing a liner dimensioned to fit in said exhaust
gas conveying apparatus, and producing capillary bores in the
liner.
10. An apparatus according to claim 6, wherein at least a partial
air gap remains between the outer wall of the liner and the
internal wall of the exhaust gas conveying apparatus, such that the
majority of the outer wall of the liner is separated from the
internal wall of the exhaust gas conveying apparatus by said air
gap.
11. An apparatus according to claim 7, wherein the apparatus is
located inside the exhaust gas tract of a motor vehicle in front of
a multi-way exhaust gas catalytic converter.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of German Application
No. DE 10 2005 004 651.7 filed Feb. 2, 2005.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to an exhaust gas conveying apparatus
of an internal combustion engine with an internal liner and a
process for its fabrication.
[0004] The continuous reduction of the permissible pollutant
emissions of motor vehicles requires continuous improvement in the
treatment of exhaust gas. Special attention is paid to the exhaust
gas treatment during the cold start phase. Immediately after the
start relatively high quantities of unburned hydrocarbons are
emitted. The reason for this, amongst others, is that the catalytic
converter has not yet reached its light-off temperature, resulting
in an insufficient conversion of the hydrocarbons.
[0005] Usually the catalytic converter reaches its light-off
temperature about one minute after the start of the engine through
the waste heat of the exhaust gas stream so that the catalytic
conversion of the exhaust gas begins.
[0006] 2. Description of Related Art
[0007] In DE 100 48 286 A1 it is proposed to buffer at least a part
of the unburned hydrocarbons. For that, a part of the exhaust gas
conduit is coated on its inside with an absorbing material,
preferably on the basis of zeolite. This coating absorbs part of
the unburned hydrocarbons during the cold start phase and releases
them again at higher temperatures. Already during the cold start
phase the coating of the exhaust manifold is exposed to exhaust
gases with temperatures of up to 1050.degree. C. This is a
disadvantage since the coating rapidly heats up to it's desorption
temperature and consequently it buffers only small amounts of
hydrocarbon during the heat up period of the catalytic converter to
its light off temperature. Furthermore, the coating which is
directly applied to the internal walls of the exhaust manifold is
exposed to high mechanical loads. It must withstand large thermal
cycles and thermal stresses resulting from the different thermal
expansion coefficients of the ceramic and the metal without
delamination of parts of the coating which would go into the
catalyst downstream.
[0008] In another approach stable porous inlays, typically high
temperature resistant sintered ceramic bodies, are laid
respectively glued into a part of the exhaust conduit. These inlays
feature a better form-stability and, with regard to easily
condensable exhaust gas constituents, better absorbing and/or
adsorbing properties. A disadvantage of this approach is the
unadjusted heat transfer or, as the case may be, heat removal. The
porous inlays are usually very efficient thermal insulators, so
that the exhaust gas is cooled to a much lesser degree by the
surfaces of the exhaust gas conduit. Although this is an advantage
during the cold start phase, since the catalytic converter reaches
its light off temperature faster, this thermal insulation also
results in a higher heat load for the catalytic converter during
continuous operation, with the danger of overheating the catalyst
material.
[0009] Since the known sintered ceramics as an inlay for exhaust
gas conveying apparatuses or conduits usually feature only a low
mechanical strength, the material of the conduit must essentially
carry the entire mechanical load, so that the construction of the
conduits cannot be designed lighter than in an apparatus without
liners. The resulting weight gain of the overall system of the
exhaust gas conduits is a disadvantage with respect to the desired
lightweight construction.
[0010] The objective of the invention is to create an exhaust gas
conveying apparatus as well as a process for its fabrication, which
features a good buffer capacity for easily condensable exhaust gas
constituents as well as a heat balance, which is adjusted to the
cold start as well as the continuous operation phase, and with
which the weight of the entire exhaust gas conveying apparatus may
only be marginally increased.
SUMMARY OF THE INVENTION
[0011] According to the invention the objective is achieved by an
exhaust gas conveying apparatus of an internal combustion engine
with internal liner, as well as a process for the fabrication of an
exhaust gas conveying apparatus of an internal combustion engine
with internal liner.
[0012] In a first embodiment according to the invention an exhaust
gas conveying apparatus of an internal combustion engine with
internal liner is featured, in which the liner features capillary
bores, which are open at least towards the exhaust gas conveying
side of the liner. The bores can either open single-sided or they
can penetrate the liner completely (through holes).
[0013] Such a modified structure of the liner of the exhaust gas
conveying apparatus with bores as described above enlarges the
active surface of the liner.
[0014] Here the active surface is referred to as the surface which
acts absorptive or adsorptive on the easily condensable exhaust gas
constituents such as light hydrocarbons (CHx). The active surface
includes the outer as well as the inner surface of the liner which
is constituted by the bores.
[0015] Such a modified structure facilitates the hydrocarbon
condensation, in particular a hydrocarbon capillary condensation,
and features in addition a capillary attraction which transports
the hydrocarbon-condensate into the interior of the structure
and/or into regions of lower exhaust gas concentration and/or
retains the hydrocarbon-condensate until its desorption.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Possible embodiments of the invention are shown in the
illustrations, which are not to scale. The illustrations are
intended to help explain the principle of the invention in more
detail and are not meant to impose any restrictions. They show:
[0017] FIG. 1 a cut-out of the side of a liner of an exhaust gas
manifold opposing the exhaust gas conveying surface with regularly
arranged laser drilled through holes.
[0018] FIG. 2 capillary bores with different orientation, diameter
and length.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The bores may be introduced into a metallic or ceramic
liner. It is advantageous if the internal wall of the apparatus and
the liner are made from materials with equal or similar thermal
conductivity, e.g. both made from metal, so that even when exposed
to large thermal cycles thermal stress is avoided or minimized. The
bores may be introduced into a solid or porous liner.
[0020] In a preferred embodiment the liner features capillary bores
with different depths and/or different diameters. The diameter of
the bores is between 10 and 1000 .mu.m, their depth is at least 10
.mu.m.
[0021] Bores with a diameter which varies, particularly decreases,
with the depth have been found to enhance condensation.
[0022] Preferably the liner features capillary bores with different
depth and/or diameter, such that they exhibit a gradient of their
active surface. For instance only part of the bores penetrates the
liner deeply or even completely whereas the major part is located
close to the surface of the liner side which is exposed to the
exhaust gas. Thus a layer close to the surface features a larger
surface than a layer further away from the surface.
[0023] Particularly advantageous is when the gradient is designed
such that the active surface varies on average at least 20% across
the overall length. The gradient may be a steady change or a change
in steps.
[0024] In an advantageous embodiment the liner features capillary
bores which are arranged perpendicular to the exhaust gas conveying
surface of the liner. Such perpendicular bores in the liner can
easily be fabricated.
[0025] In an alternative or additive advantageous embodiment the
liner features capillary bores which are inclined with respect to
the exhaust gas conveying surface of the liner. The bores maybe
inclined away from or towards the direction of the exhaust gas
stream. Advantageous angles between the bores and the surface are
between 30.degree. and 60.degree..
[0026] The inclination of the bore affects the quantity and the
speed with which the gas is absorbed, adsorbed and condensed as
well as the flow behavior of the gas. Hence it is advantageous to
locally incline the bores differently. For instance in regions
where an undisturbed flow of the gas is important the bores are
inclined towards the flow to reduce turbulence and back-mixing of
the gases. In regions with a more tranquil flow the bores are
inclined with the direction of the flow to ensure an efficient
penetration of the gas. In some regions it is advantageous to
locally design the bores with different inclination as a network
(bores not connected) or as a tunnel system (bores connected).
[0027] In a further embodiment the internal wall of the exhaust gas
conveying apparatus and the liner are connected by adhesive bond
and form fit, in which a transitional layer is formed in which the
bores of the liner are partly filled by the material of the
internal wall of the exhaust gas conveying apparatus. The material
of the liner is quasi transitioning through a two-phase structure
connecting layer into the material of the exhaust gas conveying
apparatus.
[0028] One advantage of the liner according to the invention is
that the bore structure exhibits a significantly higher stiffness
compared to the usually used porous material. In particular this is
true with a closed surface on the outside of the liner. Thereby the
wall thickness of the exhaust gas conveying apparatus, e.g. the
exhaust manifold of a motor vehicle engine, can be reduced.
[0029] Through this it is also possible to create an air gap
insulated exhaust gas conduit, in particular an air gap insulated
exhaust manifold, by designing the liner with a closed outer
surface. Between this closed outer surface of the liner and the
internal surface of the exhaust gas conveying apparatus at least
partially an air gap is located, which is typically a few
millimeters thick. Through the thermal insulation of the air gap an
advantageous improvement of the cold start properties of the
internal combustion engine is achieved. There is no necessity of an
additional air gap insulated exhaust manifold, which is
advantageous in terms of the overall weight.
[0030] Exhaust gases can reach the air gap through the bores which
penetrate the liner completely, and are buffered there in gaseous
and/or liquid form, which increases the buffer capacity even
further.
[0031] As material for the liner, composite metals and/or ceramics
are suitable. Among the preferred suitable alloys are high
temperature and oxidation resistant alloys on the bases of Ni, NiCr
and/or NiCrAl as well as high-alloyed steels. Among the well
suitable ceramics are refractory oxides like Al.sub.2O.sub.3,
ZrO.sub.2, fireclay and such, as well as SiC or
Si.sub.3N.sub.4.
[0032] A preferred variant of the metallic liner consists of two
different metal alloys, in which the first consists of a Ni
containing alloy and the second of a catalytically active noble
metal containing alloy.
[0033] Another preferred metallic variant consists of two metals
or, as the case may be, alloys, which exhibit a large difference in
their thermal conductivity.
[0034] For mixed structures consisting of ceramic and metallic
material layers it is advantageous to locate the ceramic layers on
the outside of the liner or to sandwich the ceramic layers between
metallic layers. Thereby loose ceramic particulates are trapped and
cannot be carried away by the exhaust gas stream.
[0035] An advantage of this combined design is that the outer
layers are shielded by the inner material layers, at least during
the start phase, e.g. the cold start phase, of an internal
combustion engine. This delays the heating up of the outer regions
thus prolongating the absorptive effect in this cooler region. Thus
it is for instance possible to sustain the absorptive effect of
porous zeolite or zeolite coated material in the exhaust stream of
a motor vehicle almost until it reaches the CAT light off
temperature (starting temperature of the catalytic converter).
[0036] The gradient in the structure and material of the liner,
especially in connection with the combined materials, is preferably
adjusted such that during the start phase thermal conductivity,
thermal transfer and heat capacity result in a minimal liner
heating up and a maximal heating up of the catalyst up to its CAT
light off temperature. Thus a high buffering capacity for easily
condensable exhaust gas constituents, particularly CHx, and a rapid
availability of the catalytic converter are ensured.
[0037] During the operation the liner heats up and releases the
adsorbed matter such that they can be catalytically converted by
the catalytic converter which is now above its CAT light off
temperature. The liner dissipates its surplus heat through the
surface of the exhaust gas conveying apparatus such that a possible
overheating of the catalytic converter is prevented.
[0038] Another aspect of the invention relates to a process for the
fabrication of an exhaust gas conveying apparatus of an internal
combustion engine with internal liner in which the liner is
fabricated with capillary bores.
[0039] The fabrication of a liner without bores as well as the
fitting and fastening of a liner with bores is done by well known
processes according to the state of the art. Advantageous methods
for the fabrication of the bores are sink erosion or laser drilling
which are suitable for variable diameter bores.
[0040] The liner is preferably inserted into the exhaust gas
conveying apparatus such that at least a partial air gap remains
between the outer wall of the liner and the internal wall of the
exhaust gas conveying apparatus. Particularly preferred, the
majority of the outer wall of the liner is separated from the
internal wall of the exhaust gas conveying apparatus by an air
gap.
[0041] The mechanical connection between the porous liner and the
exhaust gas conveying apparatus can be done by metallic or ceramic
spacers, which are for instance bonded or welded in place.
Furthermore the liner or, as the case may be, the internal parts,
of an air gap insulated exhaust manifold can be fabricated by means
of powder metallurgy.
[0042] According to the embodiment of the invention shown in FIG. 1
bores oriented perpendicular to the surface with a diameter of 0.5
mm and a regular distance to each other of 3 mm are machined into
the liner of an exhaust manifold by laser drilling. Then the liner
is fitted into the exhaust manifold and mounted.
[0043] According to the second embodiment of the invention shown in
FIG. 2 completely (through holes) and partially penetrating bores
are machined into the liner of an exhaust manifold spaced at
irregular distances to each other between 0 and 3 mm with various
orientations and angles to the surface and with different diameters
between 0.1 and 0.5 mm by laser drilling, such that a meshwork of
bores which are either connected or not connected to each other
results.
[0044] According to a third embodiment of the invention, which is
not shown in the illustrations, bores with a diameter decreasing
from the surface going into the liner are machined into said
liner.
* * * * *