U.S. patent application number 09/412442 was filed with the patent office on 2002-05-09 for catalyst assembly for an exhaust gas system.
Invention is credited to CIKANEK, HARRY ARTHUR, RAO, DURGA, TABACZYNSKI, RODNEY JOHN.
Application Number | 20020054838 09/412442 |
Document ID | / |
Family ID | 23632997 |
Filed Date | 2002-05-09 |
United States Patent
Application |
20020054838 |
Kind Code |
A1 |
RAO, DURGA ; et al. |
May 9, 2002 |
CATALYST ASSEMBLY FOR AN EXHAUST GAS SYSTEM
Abstract
A catalyst assembly 16 for an exhaust gas system 14 for an
automotive vehicle includes a housing 28 and a porous support
structure 32 having a plurality of channels 34, 36. A plurality of
catalyst pellets 50 are disposed within at least some of the
channels. A retainer 54 is positioned adjacent to the support
structure 32 for retaining the pellets 50 within the channels 34,
36.
Inventors: |
RAO, DURGA; (BLOOMFIELD TWP,
MI) ; CIKANEK, HARRY ARTHUR; (NORTHVILLE, MI)
; TABACZYNSKI, RODNEY JOHN; (SALINE, MI) |
Correspondence
Address: |
LYON & ARTZ PLC
28333 TELEGRAPH ROAD
SOUTHFIELD
MI
48034
|
Family ID: |
23632997 |
Appl. No.: |
09/412442 |
Filed: |
October 4, 1999 |
Current U.S.
Class: |
422/180 ;
422/177 |
Current CPC
Class: |
F01N 3/2846 20130101;
F01N 3/2828 20130101; Y02A 50/2322 20180101; F01N 3/2885 20130101;
F01N 3/28 20130101; Y02A 50/20 20180101; F01N 3/2832 20130101 |
Class at
Publication: |
422/180 ;
422/177 |
International
Class: |
B01D 053/34; B01D
053/88; B01J 035/04; F01N 003/28 |
Claims
What is claimed is:
1. A catalyst assembly for an exhaust system comprising: a housing;
a porous support structure positioned with said housing, said
support structure including a plurality of parallel channels; a
plurality of catalyst pellets disposed within at least some of said
plurality of channels; and a retainer positioned adjacent to said
support structure for retaining said pellets within said
channels.
2. A catalyst assembly as recited in claim 1 wherein said channels
are comprised of inlet channels having an open inlet end and a
closed exit end.
3. A catalyst assembly as recited in claim 2 wherein said catalyst
pellets are disposed within said inlet channels.
4. A catalyst assembly as recited in claim 2 wherein said inlet
channels comprise a catalyst coating.
5. A catalyst assembly as recited in claim 1 wherein said channels
comprises exit channels having a closed inlet end and an open exit
end.
6. A catalyst assembly as recited in claim 5 wherein said catalyst
pellets are disposed within said exit channels.
7. A catalyst assembly as recited in claim 5 wherein said exit
channels comprises a catalyst coating.
8. A catalyst assembly as recited in claim 1 wherein said catalyst
pellets have a shape selected from spherical, round and
irregular.
9. A catalyst assembly as recited in claim 1 further comprising a
second retainer positioned adjacent to the support structure.
10. A catalyst assembly as recited in claim 1 wherein said support
structure is monolithic.
11. An automotive vehicle comprising: an internal combustion engine
having an exhaust manifold emitting exhaust gas; a catalyst
assembly coupled to said exhaust manifold receiving said exhaust
gas; said catalyst assembly comprising, a housing; a porous support
structure positioned within said housing, said support structure
including a plurality of parallel channels; a plurality of catalyst
pellets disposed within at least some of said plurality of
channels; and a retainer positioned adjacent to said support
structure for retaining said pellets within said channels.
12. An automotive vehicle as recited in claim 11 wherein said
channels are comprised of inlet channels having an open inlet end
and a closed exit end and exit channels having a closed inlet end
and an open exit end.
13. An automotive vehicle as recited in claim 11 wherein said
catalyst pellets are disposed within said inlet channels.
14. An automotive vehicle as recited in claim 11 wherein said inlet
channels comprise a catalyst coating.
15. An automotive vehicle as recited in claim 11 wherein said
catalyst pellets are disposed within said exit channels.
16. An automotive vehicle as recited in claim 11 wherein said exit
channels comprises a catalyst coating.
17. An automotive vehicle as recited in claim 12 wherein said inlet
channels and said exit channels are alternatively positioned in
said support structure.
18. A catalyst assembly for an exhaust system comprising: a
housing; a porous support structure positioned with said housing,
said support structure including a plurality of parallel channels,
said parallel channels including inlet channels having an open
inlet end and a closed exit end and exit channels having an open
exit end and a closed inlet end; a plurality of catalyst pellets
disposed within said exit channels; and a retainer positioned
adjacent to said support structure for retaining said pellets
within said exit channels.
19. A catalyst assembly as recited in claim 18 wherein said
catalyst pellets are disposed within said inlet channels.
20. A catalyst assembly as recited in claim 18 wherein said inlet
channels comprises a catalyst coating.
21. A catalyst assembly as recited in claim 18 wherein said exit
channels comprises a catalyst coating.
22. A catalyst assembly as recited in claim 18 wherein said inlet
channels and said exit channels are alternatively position in said
support structure.
Description
TECHNICAL FIELD
[0001] The present invention relates generally to a catalyst
assembly for an automotive vehicle, and more particularly, to the
catalyst structure assembly.
BACKGROUND
[0002] Current production automotive vehicles have internal
combustion engines that have catalytic converters to reduce
emissions of regulated gasses. The regulated gasses include
hydrocarbons, carbon monoxide, and oxides of nitrogen. The
catalytic converter contains various catalysts that react with the
exhaust gasses to convert them into other gasses.
[0003] In addition to the catalytic converter, a muffler and
resonator are typically located in the exhaust gas path. The
muffler and resonator attenuate the sound from the internal
combustion engine. The muffler and resonator are coupled to the
tail pipe of the vehicle which typically extends out from the rear
portion of the vehicle.
[0004] It is a goal of automotive engineers to reduce the number of
parts and design complexity of the automotive vehicle. To
accommodate the muffler, catalytic converter and resonator, the
floor stamping of the vehicle is modified. The modification of the
floor stamping increases the cost of the vehicle and adds to the
design complexity.
[0005] It would therefore be desirable to reduce the cost of the
automotive vehicle by eliminating the muffler and resonator to
reduce the complexity of the vehicle.
SUMMARY OF THE INVENTION
[0006] In one aspect of the invention, a catalyst assembly for an
exhaust system comprises a housing and a porous support structure
having a plurality of channels. A plurality of catalyst pellets are
disposed within at least some of the channels. A retainer is
positioned adjacent to the support structure for retaining the
pellets within the channels.
[0007] In a further aspect of the invention, some of the plurality
of parallel channels are inlet channels and the other channels are
outlet channels. The inlet channels and the outlet channels are
coupled between the porous support structure. The plurality of
catalyst pellets may be disposed in either the inlet channels, the
outlet channels, or both. The position of the pellets depends upon
many factors including the type of engine and the amount of desired
reduction of regulated gasses.
[0008] One advantage of the invention is that the catalyst assembly
may be located relatively close to the engine manifold within the
engine compartment. Another advantage of the invention is that the
catalyst assembly may be designed to reduce the noise emissions
from the internal combustion engine and thus reduce the need for a
resonator and a muffler. Yet a further advantage of the invention
is that by eliminating the muffler and resonator, the floor
stamping for the vehicle may be reduced in complexity.
[0009] Other objects and features of the present invention will
become apparent when viewed in light of the detailed description of
the preferred embodiment when taken in conjunction with the
attached drawings and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view of an automotive vehicle having
a catalyst assembly according to the present invention.
[0011] FIG. 2 is a perspective view of a catalyst assembly
according to the present invention.
[0012] FIG. 3 is a cross-sectional view of a first embodiment of a
catalyst assembly.
[0013] FIG. 4 is a partial end view of the catalyst assembly of
FIG. 3.
[0014] FIG. 5 is a cross-sectional view of a second embodiment of a
catalyst assembly.
[0015] FIG. 6 is a partial end view of the catalyst assembly of
FIG. 5.
[0016] FIG. 7 is a third embodiment of a catalyst assembly.
[0017] FIG. 8 is a partial end view of the catalyst assembly of
FIG. 7.
[0018] FIG. 9 is a cross-sectional view of a catalyst assembly
having irregularly shaped catalyst pellets.
[0019] FIG. 10 is a cross-sectional view of a fourth embodiment of
the present invention.
[0020] FIG. 11 is a partial cross-sectional view in an enlarged
scale of a portion of FIG. 10.
[0021] FIG. 12 is an exploded view of a catalyst support structure
and a retainer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0022] Referring now to the drawings, like reference numerals are
used to identify identical components in the various views. While
the present invention is described with respect to particular
shapes and sizes of various aspects of the catalyst assembly, those
skilled in the art would recognize that various shapes and sizes of
the various aspects of the catalyst assembly may be used.
[0023] Referring now to FIG. 1, automotive vehicle 10 has an
internal combustion engine 12 that generates exhaust gasses. The
exhaust gasses exit the engine 12 through an exhaust manifold 14.
Exhaust manifold 14 is coupled to a catalyst assembly 16 through an
inlet 18. Catalyst assembly 16 has an outlet 20 that is coupled to
an exhaust system 22. The exhaust system 22 has a tail pipe 24 that
emits gasses therefrom. Catalyst assembly 16 may be directly
coupled to manifold 14 or coupled through a connecting pipe (not
shown).
[0024] As illustrated, catalyst assembly 16 is located within
engine compartment 26 of automotive vehicle 10. Catalyst assembly
16 may, however, be located at various locations along exhaust
system 22. However, by placing the catalyst assembly 16 within
engine compartment 26, the floor pan (not shown) of vehicle 10 can
be more simply designed since it does not have to accommodate the
catalyst assembly 16.
[0025] Referring now to FIG. 2, one embodiment of an oval catalyst
assembly 16 is illustrated in perspective. Catalyst assembly 16
includes a housing 28 that surrounds the internal support structure
for the catalyst material. Housing 28 is preferably formed of a
metallic material to permit heat dissipation. Inlet 18 may have a
flange 30 that is used for coupling the inlet 18 directly to the
exhaust manifold 14 of the vehicle. Housing 28 may also have outlet
20 integrally formed therewith. Outlet 20 is used to interface with
exhaust system 22.
[0026] Referring now to FIGS. 3 and 4, a cross-sectional view of a
first embodiment of catalyst assembly 16 within housing 28 is
illustrated. Housing 28 surrounds a catalyst support structure 32.
Catalyst support structure 32 is composed of a permeable ceramic
material such as Cordite. Catalyst support structure 32 preferably
has a generally rectilinear honeycomb structure consisting of a
plurality of parallel channels. The parallel channels are divided
into alternating inlet channels 34 and exit channels 36. Inlet
channels 34 are opened at an inlet end 38 of support structure 32
and plugged at the exit end 40 with a plug 42. Conversely, exit
channels 36 have a plug 44 at the inlet end 38 and are open at the
exit end 40. Inlet channels 34 and exit channels 36 are separated
by thin, porous longitudinal sidewalls 46 which permit the exhaust
gasses to pass from inlet channels 34 to exit channels 36 along
their length. In the preferred embodiment, the inlet channel 34 and
exit channels 36 have a rectangular cross-sectional shape. Channels
34, 36 are approximately 8 to 12 inches long and 0.083 inches wide.
However, the length of the inlet and exit channels may vary from 2
to 24 inches and their widths may vary from 0.05 to 0.15 inches.
The honeycomb monolithic support structure 32 provides a large
catalyzation area per unit volume. Also, the channels 34, 36 reduce
the noise between the inlet end 38 and the exit end 40. The support
structure 32 also provides noise attenuation due to the path the
noise takes through the inlet and exit channels.
[0027] The porous walls 46 separating the inlet channels 34 from
the exit channels 36 are approximately 0.107 inches thick. The
pores (shown in FIG. 11) in sidewalls 46 are small enough to allow
exhaust gasses to be catalyzed and pass therethrough.
[0028] An oxidation catalyst 48 is deposited on the internal
surfaces of inlet channels 34 and exit channels 36. Oxidation
catalyst 48 may be platinum, paladium or a platinum-paladium alloy
such as that used in current automotive catalytic converters. As is
known in the art, platinum, paladium and alloys thereof are
catalysts which promote the oxidation of the hydrocarbons and
carbon monoxide byproducts of the exhaust gasses.
[0029] Inlet 34 has catalyzed pellets 50 disposed therein.
Catalyzed pellets 50 may be formed from a catalyst material or may
have a catalyst coating 52. In this embodiment, each inlet channel
34 is filled with catalyzed pellets 50. As illustrated, catalyzed
pellets 50 are spherical. However, catalyzed pellets 50 may be one
of a number of shapes such as oval, oblong, cylindrical or an
irregular shape.
[0030] A retainer 54 is used to hold the catalyzed pellets 50 into
inlet channels 34. Retainer 54 is used to tightly hold catalyzed
pellets 50 in place so that they do not rattle. Retainer 54 must be
capable of withstanding the temperatures typically found in exhaust
gasses. Also, retainer 54 must be durable to last through the life
of the vehicle. Suitable materials for retainer 54 include
stainless steel wire mesh and temperature woven ceramic fabric such
as ZrAlSiO.sub.2.
[0031] In operation, exhaust gasses as represented by arrows 56
enter housing 28 through inlet 18. The exhaust gasses 56 enter
inlet channels 34 and pass by catalyzed pellets 50. The oxidation
catalyst 48 and the catalyzed pellets 50 convert noxious gasses in
the exhaust gas 50 into more desirable gasses. Gasses flow from
inlet channels 34 into sidewalls 46 and into exit channels 36.
Further, catalyzation takes place with the oxidation catalyst 48
within exit channels 36.
[0032] Referring now to FIGS. 5 and 6, in this second embodiment of
a catalyst assembly 16', catalyzed pellets 50 are placed within
exit channels in contrast to FIGS. 3 and 4 above. This embodiment
protects catalyzed pellets 50 from impurities in the exhaust
stream. For example, oil additives such as zinc thiophosphate may
damage particular catalysts. In this embodiment, the exhaust gasses
56 first contact oxidation catalysts 48 in inlet channels 34. The
exhaust gasses partially purified by oxidation catalyst 48 travel
through sidewalls 46 and into exit channels 36 through another
oxidation catalyst 48. In this embodiment, retainer 54 is
positioned at exit end 40 to retain the catalyzed pellets 50 within
exit channels 36.
[0033] Referring now to FIGS. 7 and 8, in this third embodiment of
a catalyst assembly 16", both inlet channels 34 and exit channels
36 have catalyzed pellets 50 disposed therein. To retain pellets 50
within exit channels 36, a second retainer 54' is used. This
embodiment provides the greatest surface area for contact with the
exhaust gas with the catalyst. This embodiment also provides
capability of providing a unique oxide of nitrogen absorbing
catalyst in the inlet channel 34 with a reducing atmosphere. Exit
channels 36 and catalyzed pellets 50 provide a further oxidizing
atmosphere for the majority of the engine regime operation. This
embodiment also provides an opportunity for emission reduction
during cold starts.
[0034] In the above embodiments, acoustic attenuation of the
catalyst support structure 32 is enhanced by adding catalyzed
pellets 50 into inlet channels 34, exit channels 36 or the
combination of both.
[0035] Referring now to FIG. 9, an embodiment similar to that shown
in FIGS. 7 and 8 is illustrated. That is, catalyzed pellets 50 are
disposed within both the inlet channels 34 and exit channels 36.
However, in this embodiment the catalyzed pellets comprise
cylindrical pellets 58, spherical pellets 60, oblong pellets 62,
and irregular pellets 64. Pellets 58 through 64 can be mixed and
matched in any support structure 32 to optimize gas flow,
acoustics, and/or emission control. Pellets 58 through 64 may be
coated or uncoated, etched or unetched, and may be mixed in the
various inlet or exit channels the materials that the pellets are
made from may also vary.
[0036] Referring now to FIG. 10, a portion of catalyst assembly 16
is illustrated. In this embodiment, catalyzed pellets 50 are
adjacent to the sides of inlet channels 34 and exit channels
36.
[0037] Referring now to FIG. 11, the catalyst material 66 is also
preferably present within pores 68 of sidewalls 46. By providing
catalyst material 66 within pores 68, the converted exhaust gas is
increased by providing an increase in surface area providing a more
intimate contact of the exhaust gasses with the oxidation layer as
exhaust gasses pass from inlet channel 34 to exit channel 36.
[0038] Referring now to FIG. 12, retainer 54 is shown with respect
to catalyst support structure 32. Catalyst support structure 32 in
this embodiment is oval in shape. Retainer 54 has a correspondingly
oval shape. Retainer 54 is preferably comprised of a fine mesh 70
that allows catalyzed pellets 50 to be retained tightly within
their respective inlet channels 34 or exit channels 36. A frame 72
extends around mesh 70 to allow mesh 70 to be fastened to catalyst
support structure 32. A retainer bar 74 is positioned across mesh
70 to prevent movement of mesh 70 during the operation of the
vehicle. Retainer bar 74 assists mesh 70 in firmly retaining
catalyzed pellets 50 within the inlet channels 34 or exit channels
36. In an embodiment providing catalyzed pellets 50 in both inlet
channels 34 and exit channels 36, the second retainer 54' may be
similarly configured.
[0039] While particular embodiments of the invention have been
shown and described, numerous variations and alternate embodiments
will occur to those skilled in the art. Accordingly, it is intended
that the invention be limited only in terms of the appended
claims.
* * * * *