U.S. patent application number 10/763646 was filed with the patent office on 2005-03-10 for method and apparatus for filtering exhaust particulates.
Invention is credited to Cheng, Shi-Wai S..
Application Number | 20050050870 10/763646 |
Document ID | / |
Family ID | 34227101 |
Filed Date | 2005-03-10 |
United States Patent
Application |
20050050870 |
Kind Code |
A1 |
Cheng, Shi-Wai S. |
March 10, 2005 |
Method and apparatus for filtering exhaust particulates
Abstract
A particulate filter for an exhaust system configured to manage
an exhaust flow includes a housing and a wall-flow filtration
element contained within the housing. The wall-flow filtration
element is configured to trap exhaust particulates and to pass ash
particles.
Inventors: |
Cheng, Shi-Wai S.; (Troy,
MI) |
Correspondence
Address: |
KATHRYN A MARRA
General Motors Corporation
Legal Staff, Mail Code 482-C23-B21
P.O. Box 300
Detroit
MI
48265-3000
US
|
Family ID: |
34227101 |
Appl. No.: |
10/763646 |
Filed: |
March 3, 2003 |
Current U.S.
Class: |
55/523 |
Current CPC
Class: |
Y02T 10/20 20130101;
C04B 38/0006 20130101; B01D 46/2459 20130101; B01D 2275/30
20130101; B01D 2046/2437 20130101; B01D 46/244 20130101; F01N
2330/06 20130101; F01N 3/0222 20130101; Y02T 10/22 20130101; B01D
53/9454 20130101; B01D 2046/2433 20130101; F01N 2330/60 20130101;
Y10S 55/05 20130101; C04B 2111/00793 20130101; B01D 46/2455
20130101; Y10S 55/10 20130101; B01D 2046/2496 20130101; B01D
46/2474 20130101; Y10S 55/30 20130101; Y10T 428/24149 20150115;
Y02T 10/12 20130101; B01D 46/2451 20130101; C04B 38/0006 20130101;
C04B 35/00 20130101; C04B 38/0012 20130101; C04B 38/0054 20130101;
C04B 38/0096 20130101; C04B 38/0006 20130101; C04B 35/00 20130101;
C04B 38/0012 20130101; C04B 38/0054 20130101; C04B 38/0096
20130101 |
Class at
Publication: |
055/523 |
International
Class: |
B01D 046/00 |
Claims
What is claimed is:
1. A particulate filter for an exhaust system configured to manage
an exhaust flow, comprising: a housing; and a wall-flow filtration
element contained within said housing, said wall-flow filtration
element having pores defining a porosity sufficient to trap exhaust
particulates and to pass ash particles.
2. The particulate filter of claim 1, wherein: said wall-flow
filtration element comprises an inlet channel with an inlet port at
one end and a first end-plug at the opposite end, and an outlet
channel with an outlet port at one end and a second end-plug at the
opposite end; said inlet channel being in fluid communication with
said outlet channel; said wall-flow filtration element arranged to
receive the exhaust flow at said inlet port and to discharge the
exhaust flow at said outlet port; and said first end-plug having
greater porosity than said second end-plug.
3. The particulate filter of claim 2, wherein: said wall-flow
filtration element comprises a ceramic monolith structure having a
plurality of porous internal walls defining said inlet and outlet
channels, said inlet and outlet channels being separated by said
porous internal walls to permit exhaust flow through the pores
between said inlet and outlet channels.
4. The particulate filter of claim 2, wherein the pores of said
first end-plug are configured to trap exhaust particulates and
permit leakage of ash particles.
5. The particulate filter of claim 4, wherein the pore size of said
first end-plug is equal to or greater than about 30
micrometers.
6. The particulate filter of claim 5, wherein the pore size of said
first end-plug is equal to or greater than about 30 micrometers and
equal to or less than about 60 micrometers.
7. The particulate filter of claim 2, wherein: said housing
comprises a first end and a second end; said inlet port of said
inlet channel being at said first end of said housing; and said
outlet port of said outlet channel being at said second end of said
housing.
8. The particulate filter of claim 3, wherein the total surface
area of said first end-plug is substantially less than the total
surface area of said internal walls.
9. The particulate filter of claim 3, wherein said inlet and outlet
channels and said internal walls are arranged parallel to the
exhaust flow.
10. A particulate filter for an exhaust system configured to manage
an exhaust flow, comprising: a housing having a first end and a
second end; a wall-flow filtration element arranged within said
housing comprising a ceramic monolith structure having a plurality
of porous internal walls defining inlet and outlet channels, said
inlet and outlet channels being separated by said porous internal
walls to permit exhaust flow through the pores between said inlet
and outlet channels; said inlet channel comprising an inlet port at
one end and a first end-plug at the opposite end and configured to
receive the exhaust flow at said inlet port, said inlet port
arranged at said first end of said housing; said outlet channel
comprising an outlet port at one end and a second end-plug at the
opposite end and configured to discharge the exhaust flow at said
outlet port, said outlet port arranged at said second end of said
housing; and said first end-plug having greater porosity than said
second end-plug.
11. The particulate filter of claim 10, wherein: the pores of said
first end-plug are configured to trap exhaust particulates and
permit leakage of ash particles; the total surface area of said
first end-plug is substantially less than the total surface area of
said internal walls; and said inlet and outlet channels and said
internal walls are arranged parallel to the exhaust flow.
12. A method for filtering particulates of an exhaust flow of an
exhaust system, comprising: receiving the exhaust flow at one end
of a particulate filter having a ceramic monolith structure with
porous walls defining inlet channels and outlet channels, the inlet
channels each having an inlet port at one end to receive the
exhaust flow and a porous plug at the opposite end, the outlet
channels each having an outlet port at one end to discharge the
exhaust flow and an end plug at the opposite end; filtering the
exhaust flow at the ceramic monolith structure as the exhaust flow
passes through the porous walls between the inlet and outlet
channels; trapping exhaust byproducts at the porous walls, the end
plugs, and the porous plugs, and passing ash particles through the
porous plugs; and discharging the exhaust flow at the outlet
ports.
13. The method of claim 12, further comprising: regenerating the
ceramic monolith structure and converting the trapped exhaust
particulates into ash particles.
14. The method of claim 12, wherein said trapping further
comprises: trapping ash particles at the porous walls and end
plugs.
15. The method of claim 12, wherein said passing further comprises:
passing ash particles through the porous plugs having a pore size
of equal to or greater than about 30 micrometers.
16. The method of claim 15, wherein said passing further comprises:
passing ash particles through the porous plugs having a pore size
equal to or greater than about 30 micrometers and equal to or less
than about 60 micrometers.
17. The method of claim 12, wherein said receiving further
comprises: receiving the exhaust flow in a direction parallel to
the inlet and outlet channels.
Description
BACKGROUND OF THE INVENTION
[0001] The present disclosure relates generally to an exhaust
system, and particularly to a particulate filter for an exhaust
system.
[0002] Automotive exhaust systems for diesel and other internal
combustion engines typically include a filtration system that
limits the mass of particulate matter emitted with the exhaust
gases. In diesel engine systems, this matter typically includes
carbonaceous matter (soot) and ash particles. Present filtering
methods to trap the exhaust particulates focus on wall-flow
filtration. Wall-flow filtration systems typically have a high
filtration efficiency not only for exhaust particulates but also
for ash particles. Catalytic or thermal arrangements within the
exhaust system, which serve to effect regeneration of the
filtration element, cannot remove ash particles, thereby increasing
the accumulation of ash particles within the filtration body with
time. In view of present particulate filter arrangements, it is
desirable to have a more advanced particulate filter that can
operate with effective filtration and with limited accumulation of
ash particles over time.
SUMMARY OF THE INVENTION
[0003] In one embodiment, a particulate filter for an exhaust
system configured to manage an exhaust flow includes a housing and
a wall-flow filtration element contained within the housing. The
wall-flow filtration element is configured to trap exhaust
particulates and to pass ash particles.
[0004] In another embodiment, a particulate filter for an exhaust
system configured to manage an exhaust flow includes a housing
having a first end and a second end and a wall-flow filtration
element arranged within the housing. The wall-flow filtration
element includes a ceramic monolith structure having porous
internal walls defining inlet and outlet channels, the inlet and
outlet channels being separated by the porous internal walls to
permit exhaust flow through the pores between the inlet and outlet
channels. The inlet channels have inlet ports at one end and first
end-plugs at the opposite end and are configured to receive the
exhaust flow at the inlet ports, the inlet ports being arranged at
the first end of the housing. The outlet channels have outlet ports
at one end and second end-plugs at the opposite end and are
configured to discharge the exhaust flow at the outlet ports, the
outlet ports being arranged at the second end of the housing. The
first end-plugs have greater porosity than the second
end-plugs.
[0005] In a further embodiment, a method for filtering particulates
of an exhaust flow of an exhaust system is disclosed. The exhaust
flow is received at one end of a particulate filter having a
ceramic monolith structure with porous walls defining inlet
channels and outlet channels, the inlet channels each having an
inlet port at one end to receive the exhaust flow and a porous plug
at the opposite end, the outlet channels each having an outlet port
at one end to discharge the exhaust flow and an end plug at the
opposite end. The exhaust flow is filtered at the ceramic monolith
structure as the exhaust flow passes through the porous walls
between the inlet and outlet channels, exhaust byproducts are
trapped at the porous walls, the end plugs, and the porous plugs,
and ash particles are passed through the porous plugs. The exhaust
flow is discharged at the outlet ports.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Referring to the exemplary drawings wherein like elements
are numbered alike in the accompanying Figures:
[0007] FIG. 1 depicts an exhaust system employing an embodiment of
the invention;
[0008] FIG. 2 depicts an isometric view of a particulate filter in
accordance with an embodiment of the invention; and
[0009] FIG. 3 depicts a cross section view of the particulate
filter of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
[0010] An embodiment of the invention provides a particulate filter
for an exhaust system of an automotive diesel engine. While the
embodiment described herein depicts an automotive diesel engine as
an exemplary diesel powerplant using a particulate filter, it will
be appreciated that the disclosed invention may also be applicable
to other diesel powerplants that require the functionality of the
particulate filter herein disclosed, such as a diesel powered
generator for example. While the disclosed invention is well suited
for filtering the combustion byproducts of a diesel engine, it may
also be applicable for filtering combustion byproducts of a
gasoline powered engine.
[0011] An exemplary exhaust system 100 for an automotive diesel
engine (not shown) is depicted in FIG. 1 having a manifold exhaust
pipe 110 suitably connected at one end to an exhaust manifold (not
shown) of the diesel engine (not shown) for receiving an exhaust
flow depicted generally as numeral 150. Turbocharger 140 is
suitably connected to intermediate manifold exhaust pipe 110 and
intermediate exhaust pipe 120. Intermediate exhaust pipe 120 is
suitably connected to a particulate filter 200 for trapping exhaust
particulates present in the exhaust flow 150, which is suitably
connected to an exhaust pipe 130. A tailpipe (not shown) for
exhausting the conditioned exhaust flow to atmosphere is suitably
connected to exhaust pipe 130. Exhaust system 100 manages the
exhaust flow 150 by controlling how the exhaust flow 150 passes
from exhaust manifolds (not shown) to manifold exhaust pipe 110,
turbocharger 140, intermediate exhaust pipe 120, particulate filter
200, exhaust pipe 130, and then to atmosphere. Exhaust system 100
has a nominal flow area equal to or greater than the inside
cross-sectional flow area of manifold exhaust pipe 110.
[0012] Each particulate filter 200 has a housing 210, which may be
any form of construction and configuration suitable for the
purpose, and a filter element 220 suitably contained within housing
210, best seen by now referring to FIG. 2. In an embodiment, filter
element 220 is a ceramic monolith structure. Filter element 220 is
of the wall-flow filtration type, meaning that exhaust flow 150
passes from the inlet channels 230, through the porous internal
walls 240, to the outlet channels 250. Filtering of the exhaust
flow 150 primarily occurs as exhaust flow 150 passes through the
pores of internal walls 240, hence the term wall-flow filtration.
Filter element 220 is configured to trap exhaust particulates and
to pass, or leak, ash particles (accumulated ash particles are
depicted generally at 330 in FIG. 3).
[0013] Inlet channels 230 each have an inlet port 260 at one end
310 and a porous end-plug 270 at the opposite end 320. Outlet
channels 250 each have an outlet port 280 at one end 320 and an
end-plug 290 at the opposite end 310. Exhaust flow 150 enters
filter element 220 at inlet ports 260, passes through porous
internal walls 240, and is discharged from filter element 220 at
outlet ports 280. In this manner, inlet channels 230 and outlet
channels 250 are referred to as being in fluid communication with
each other via internal walls 240. To facilitate the trapping of
exhaust particulates and the leakage of ash particles at porous
end-plugs 270 (the leakage of ash particles is depicted generally
at arrows 340 in FIG. 3), porous end-plugs 270 are fabricated with
a pore size equal to or greater than about 30 micrometers, and are
preferably on the order of about 30 micrometers to about 60
micrometers. Internal walls 240 of filter element 220 are
fabricated with a pore size less than about 30 micrometers, thereby
enabling the entrapment of exhaust particulates. End-plugs 290 may
be solid or may have a porosity similar to that of internal walls
240. In this manner, the artisan will readily recognize that in
general, porous end-plugs 270 have a greater porosity than
end-plugs 290.
[0014] In an embodiment depicted in FIG. 2, filter element 220 is a
ceramic monolith structure having a plurality of porous internal
walls 240 that define and separate the inlet and outlet channels
230, 250. Inlet and outlet channels 230, 250 are arranged parallel
to the direction of exhaust flow 150, resulting in a sideways flow
(depicted generally by arrows 300 in FIG. 3) as exhaust flow 150
passes through internal walls 240. Housing 210 includes a first end
310 and a second end 320. Inlet ports 260 and end-plugs 290 are
arranged at first end 310, and outlet ports 280 and porous
end-plugs 270 are arranged at second end 320. In an embodiment, and
as depicted illustratively in FIGS. 2 and 3, the overall surface
area of porous end-plugs 270 is substantially less than the total
surface area of internal walls 240, with an exemplary ratio being
less than about 1:240.
[0015] The process by which particulate filter 200 filters
particulates from exhaust flow 150 of exhaust system 100 will now
be described with reference to FIGS. 2 and 3. Exhaust flow 150 is
received at first end 310 of particulate filter 200, which has a
ceramic monolith structure (depicted as 220) with porous walls
(depicted as 240) defining inlet channels 230 and outlet channels
250. Inlet channels 230 have inlet ports 260 at first end 310 to
receive exhaust flow 150 and porous end-plugs 270 at second end 320
to leak ash (depicted generally at 340). Exhaust flow 150 is in a
direction parallel to the inlet and outlet channels 230, 250. The
leakage of ash is typically more prevalent after regeneration where
catalytic or thermal heating before or within particulate filter
200 burns the carbonaceous part of the exhaust particulates and
assists in the separation of ash from soot.
[0016] In an embodiment, particulate filter 200 includes a known
suitable heating means, such as electrical heater means or fuel
burner means, not shown, to supply necessary heat to effect
incineration of particles previously trapped by ceramic monolith
structure 220 to effect regeneration thereof. Regeneration of
ceramic monolith structure 220 serves to convert a substantial
portion of the trapped exhaust particulates into ash particles for
subsequent leakage through porous end-plugs 270.
[0017] Outlet channels 250 have outlet ports 280 at second end 320
to discharge exhaust flow 150 and end-plugs 290 at first end 310 to
block the incoming exhaust flow 150. Exhaust flow 150 is filtered
at the ceramic monolith structure 220 as it passes through the
porous walls 240 between inlet and outlet channels 230, 250.
Exhaust byproducts, such as metallic particles and carbonaceous
matter, are trapped at porous walls 240, end-plugs 290, and porous
end-plugs 270, whereas ash particles are passed, or more
specifically leaked, through porous end-plugs 270. The filtered
exhaust flow 150 is then discharged at outlet ports 280.
[0018] As discussed above, porous end-plugs 270 have a pore size
equal to or greater than about 30 micrometers, and preferably have
a pore size equal to or greater than about 30 micrometers and equal
to or less than about 60 micrometers. Porous walls 240 and
end-plugs 290, due to the pore size at those locations, do not
permit leakage of ash particles, thereby trapping some of the ash
particles within particulate filter 200.
[0019] As disclosed, an embodiment of the invention provides for
ash leakage from particulate filter 200 through porous end-plugs
270, thereby reducing or negating the need for mechanical cleaning
of the ash particles from the particulate filter 200.
[0020] While the invention has been described with reference to
exemplary embodiments, it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended claims.
Moreover, the use of the terms first, second, etc. do not denote
any order or importance, but rather the terms first, second, etc.
are used to distinguish one element from another. Furthermore, the
use of the terms a, an, etc. do not denote a limitation of
quantity, but rather denote the presence of at least one of the
referenced item.
* * * * *