U.S. patent application number 14/453062 was filed with the patent office on 2016-02-11 for particulate filter and method for control.
The applicant listed for this patent is GM GLOBAL TECHNOLOGY OPERATIONS LLC. Invention is credited to Gongshin Qi, Charles E. Solbrig.
Application Number | 20160040579 14/453062 |
Document ID | / |
Family ID | 55134948 |
Filed Date | 2016-02-11 |
United States Patent
Application |
20160040579 |
Kind Code |
A1 |
Solbrig; Charles E. ; et
al. |
February 11, 2016 |
PARTICULATE FILTER AND METHOD FOR CONTROL
Abstract
An exhaust treatment system comprises a filter device in
communication with the engine and configured to receive exhaust gas
therefrom. The filter device comprises a canister including an
inlet, a filter structure having an upstream, inlet end, a
downstream, outlet end, and a series of filtering flow passages. A
center zone conduit is in sealing, fluid contact with the
downstream, outlet end of the filter structure to thereby define a
center flow zone and perimeter flow zone. A flow control valve
assembly is disposed in the center zone conduit. A controller is in
signal communication with the flow control valve and a temperature
sensor and monitors a temperature profile of the filter structure
wherein, upon a determination that the temperature of the center
flow zone of the filter structure is above a predetermined level,
the controller drives the flow control valve assembly to a closed
position.
Inventors: |
Solbrig; Charles E.;
(Ypsilanti, MI) ; Qi; Gongshin; (Troy,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GM GLOBAL TECHNOLOGY OPERATIONS LLC |
DETROIT |
MI |
US |
|
|
Family ID: |
55134948 |
Appl. No.: |
14/453062 |
Filed: |
August 6, 2014 |
Current U.S.
Class: |
60/274 ; 60/297;
60/311 |
Current CPC
Class: |
F01N 2900/1602 20130101;
F01N 9/002 20130101; F01N 13/017 20140601; F01N 3/0217 20130101;
F01N 13/009 20140601; F01N 9/00 20130101; Y02T 10/47 20130101; F01N
3/0211 20130101; F01N 2240/36 20130101; F01N 2560/06 20130101; Y02T
10/12 20130101; F01N 3/0235 20130101; F01N 3/0222 20130101; Y02T
10/40 20130101; F01N 3/2066 20130101; Y02T 10/24 20130101; F01N
3/035 20130101 |
International
Class: |
F01N 9/00 20060101
F01N009/00; F01N 3/021 20060101 F01N003/021; F01N 3/035 20060101
F01N003/035 |
Claims
1. An exhaust treatment system for an internal combustion engine
comprising: a particulate filter device in fluid communication with
the internal combustion engine and configured to receive exhaust
gas therefrom, comprising: a canister that includes an inlet for
receipt of the exhaust gas; a filter structure having an upstream,
inlet end, a downstream, outlet end, and a series of filtering flow
passages extending therebetween; a center zone conduit in sealing,
fluid contact with the downstream, outlet end of the filter
structure to thereby define the filter structure into a center flow
zone and perimeter flow zone; a flow control valve assembly
disposed in the center zone conduit and operable between an open
and a closed position; a temperature sensor; and a controller in
signal communication with the flow control valve and the
temperature sensor and configured to monitor a temperature profile
of the filter structure wherein, upon a determination that the
temperature of the center flow zone of the filter structure has
risen above a predetermined level, the controller will drive the
flow control valve assembly to a closed position to thereby stop
the flow of exhaust gas through the center flow zone of the filter
and reduce the temperature thereof.
2. The exhaust treatment system of claim 1, the particulate filter
device further comprises a ceramic wall-flow filter supported by an
insulating mat and disposed in a rigid canister.
3. The exhaust treatment system of claim 1, further comprising one
or more of an oxidation catalyst device and a selective catalyst
reduction device.
4. The exhaust treatment system of claim 1, wherein, upon a
determination that the temperature of the center flow zone of the
filter structure has dropped below a predetermined level, the
controller will drive the flow control valve assembly to an open
position to thereby allow the flow of exhaust gas through the
center flow zone of the filter.
5. A method for controlling the temperature of a particulate filter
in an exhaust treatment system for an internal combustion engine
comprising the steps of: placing a particulate filter device in
fluid communication with the internal combustion engine and
configuring it to receive exhaust gas therefrom, the device
comprising: a canister that includes an inlet for receipt of the
exhaust gas and a filter structure having an upstream, inlet end, a
downstream, outlet end, and a series of filtering flow passages
extending therebetween; locating a center zone conduit in sealing,
fluid contact with the downstream, outlet end of the filter
structure to thereby define the filter structure into a center flow
zone and perimeter flow zone; positioning a flow control valve
assembly in the center zone conduit that is operable between an
open and a closed position; locating a temperature sensor at the
downstream, outlet end of the filter structure; and operating a
controller to monitor a temperature profile of the filter structure
wherein, upon determining that the temperature of the center flow
zone of the filter structure has risen above a predetermined level,
the controller will drive the flow control valve assembly to a
closed position to thereby stop the flow of exhaust gas through the
center flow zone of the filter and reduce the temperature
thereof.
6. The method of claim 5, further comprising the steps of,
operating the controller to monitor the temperature profile of the
filter structure wherein upon a determination that the temperature
of the center flow zone of the filter structure has dropped below a
predetermined level, the controller will drive the flow control
valve assembly to an open position to thereby allow the flow of
exhaust gas through the center flow zone of the filter.
7. An exhaust treatment system for an internal combustion engine
comprising: a particulate filter device in fluid communication with
the internal combustion engine and configured to receive exhaust
gas therefrom, comprising: a canister that includes an inlet for
receipt of the exhaust gas; a filter structure having an upstream,
inlet end, a downstream, outlet end, and a series of filtering flow
passages extending therebetween; a center zone conduit in sealing,
fluid contact with an end of the filter structure to thereby define
the filter structure into a center flow zone and perimeter flow
zone; a flow control valve assembly disposed in the center zone
conduit and operable between an open and a closed position; a
temperature sensor; and a controller in signal communication with
the flow control valve and the temperature sensor and configured to
monitor a temperature profile of the filter structure wherein, upon
a determination that the temperature of the center flow zone of the
filter structure has risen above a predetermined level, the
controller will drive the flow control valve assembly to a closed
position to thereby stop the flow of exhaust gas through the center
flow zone of the filter and reduce the temperature thereof.
8. The exhaust treatment system of claim 7, wherein, upon a
determination that the temperature of the center flow zone of the
filter structure has dropped below a predetermined level, the
controller will drive the flow control valve assembly to an open
position to thereby allow the flow of exhaust gas through the
center flow zone of the filter.
Description
FIELD OF THE INVENTION
[0001] The subject invention relates to particulate filters
suitable for the removal of particulates in the exhaust gas of
internal combustion engines and, in particular, a system that
controls the flow of exhaust gas through a particulate filter when
the flow of the exhaust gas is reduced to a rate that induces a
temperature increase therein.
BACKGROUND
[0002] Exhaust gas emitted from an internal combustion (IC) engine
is a heterogeneous mixture that contains gaseous emissions such as
carbon monoxide (CO), unburned hydrocarbons (HC) and oxides of
nitrogen (NOx) as well as condensed phase materials (liquids and
solids) that constitute particulate matter (PM). Catalyst
compositions, that are typically disposed on catalyst supports or
substrates, are provided in an engine exhaust system to convert
certain, or all of these exhaust constituents into non-regulated
exhaust gas components.
[0003] An exhaust treatment technology in use for PM reduction is
the particulate filter (PF) device. There are several known filter
structures used in PF devices such as ceramic honeycomb wall flow
filters, wound or packed fiber filters, open cell foam filters,
sintered metal filters, sintered metal foams, etc. Ceramic
honeycomb wall flow filters have experienced significant acceptance
in automotive applications. One potential drawback to the ceramic
filter (and any filter with significant particulate loading) is its
operational limits at higher temperatures. A mode of operation
which can affect the performance of the particulate filter is a
sudden reduction of exhaust flow, with high levels of oxygen,
through the PF device during a regeneration event in which the
collected particulate matter is being oxidized. The regeneration
event is used to clean the particulate filter and to reduce
backpressure experienced by the internal combustion engine. During
the regeneration event, temperatures are high and a sudden
reduction in exhaust flow through the particulate filter can reduce
heat transfer from the filter, especially near the center portion
where heat transfer is low, causing durability reducing temperature
excursions.
[0004] Accordingly, it is desirable to provide a system to control
the flow of exhaust gas through the PF device, particularly the
center portion, during high temperature events, such as
regeneration, to avoid performance reducing temperature
excursions.
SUMMARY OF THE INVENTION
[0005] In an exemplary embodiment, an exhaust treatment system for
an internal combustion engine comprises a particulate filter device
in fluid communication with the internal combustion engine and
configured to receive exhaust gas therefrom. The particulate filter
device comprises a canister that includes an inlet for receipt of
the exhaust gas, a filter structure having an upstream, inlet end,
a downstream, outlet end, and a series of filtering flow passages
extending therebetween. A center zone conduit is in sealing, fluid
contact with the downstream, outlet end of the filter structure to
thereby define the filter structure into a center flow zone and
perimeter flow zone. A flow control valve assembly is disposed in
the center zone conduit and is operable between an open and a
closed position. A temperature and a controller is in signal
communication with the flow control valve and the temperature
sensor and is configured to monitor a temperature profile of the
filter structure wherein, upon a determination that the temperature
of the center flow zone of the filter structure has risen above a
predetermined level, the controller will drive the flow control
valve assembly to a closed position to thereby stop the flow of
exhaust gas through the center flow zone of the filter and reduce
the temperature thereof.
[0006] In another exemplary embodiment, a method for controlling
the temperature of a particulate filter in an exhaust treatment
system for an internal combustion engine comprising the steps of
placing a particulate filter device in fluid communication with the
internal combustion engine and configuring it to receive exhaust
gas therefrom. The device comprises a canister that includes an
inlet for receipt of the exhaust gas and a filter structure having
an upstream, inlet end, a downstream, outlet end, and a series of
filtering flow passages extending therebetween. The steps further
include locating a center zone conduit in sealing, fluid contact
with the downstream, outlet end of the filter structure to thereby
define the filter structure into a center flow zone and perimeter
flow zone; positioning a flow control valve assembly in the center
zone conduit that is operable between an open and a closed
position; locating a temperature sensor at the downstream, outlet
end of the filter structure; and operating a controller to monitor
a temperature profile of the filter structure wherein, upon
determining that the temperature of the center flow zone of the
filter structure has risen above a predetermined level, the
controller will drive the flow control valve assembly to a closed
position to thereby stop the flow of exhaust gas through the center
flow zone of the filter and reduce the temperature thereof.
[0007] In yet another exemplary embodiment, an exhaust treatment
system for an internal combustion engine comprises a particulate
filter device in fluid communication with the internal combustion
engine and configured to receive exhaust gas therefrom. The
particulate filter device comprises a canister that includes an
inlet for receipt of the exhaust gas, a filter structure having an
upstream, inlet end, a downstream, outlet end, and a series of
filtering flow passages extending therebetween. A center zone
conduit is in sealing, fluid contact with an end of the filter
structure to thereby define the filter structure into a center flow
zone and perimeter flow zone. A flow control valve assembly is
disposed in the center zone conduit and is operable between an open
and a closed position. A temperature and a controller is in signal
communication with the flow control valve and the temperature
sensor and is configured to monitor a temperature profile of the
filter structure wherein, upon a determination that the temperature
of the center flow zone of the filter structure has risen above a
predetermined level, the controller will drive the flow control
valve assembly to a closed position to thereby stop the flow of
exhaust gas through the center flow zone of the filter and reduce
the temperature thereof.
[0008] The above features and advantages and other features and
advantages of the invention are readily apparent from the following
detailed description of the invention when taken in connection with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Other features, advantages and details appear, by way of
example only, in the following detailed description of the
embodiments, the detailed description referring to the drawings in
which:
[0010] FIG. 1 is a schematic diagram of an exhaust gas treatment
system for an internal combustion engine embodying features of the
invention;
[0011] FIG. 2 is a schematic view of a particulate filter device
for an exhaust treatment system of an internal combustion engine,
embodying features of the invention; and
[0012] FIG. 3 is a schematic sectional view, taken along line 3-3
of FIG. 2.
DESCRIPTION OF THE EMBODIMENTS
[0013] The following description is merely exemplary in nature and
is not intended to limit the present disclosure, its application or
uses. It should be understood that, throughout the drawings,
corresponding reference numerals indicate like or corresponding
parts and features. As used herein, the term vehicle is not limited
to just an automobile, truck, van or sport utility vehicle, but
includes any self-propelled or towed conveyance suitable for
transporting a burden.
[0014] Referring now to FIG. 1, exemplary embodiments of the
present disclosure are directed to an exhaust gas treatment system
10 that reduces various constituents in exhaust gas 11 generated by
an internal combustion engine 12 of the type that may commonly be
applied in automotive applications. It is appreciated that the
exhaust treatment system 10 described herein may be utilized with
various engine systems that may include, for example, but are not
limited to, diesel engines and gasoline engines.
[0015] Combustion air 13 is drawn into the engine 12 and mixed with
fuel (not shown). The air/fuel mixture is combusted and is expelled
as exhaust gas 11 through exhaust conduits 16 that are in fluid
communication with the exhaust treatment system 10. The exhaust
treatment system 10 generally includes one or more exhaust conduit
segments extending between one or more exhaust treatment devices.
The exhaust treatment devices may include an oxidation catalyst
device (OC) 20, a selective catalyst reduction device (SCR) 22, and
a particulate filter (PF) device 24. Other configurations are
contemplated.
[0016] Referring now to FIG. 2, with continuing reference to FIG.
1, a PF device 24 comprises a filter structure such as a ceramic
wall-flow filter 26 that is supported by an insulating mat 28 in a
rigid canister 30. The rigid canister 30 is typically constructed
of stainless steel or other durable, high temperature material and
includes an inlet 32 in fluid communication with exhaust conduit 16
for receipt of exhaust gas 11. The filter structure 26 includes an
upstream, inlet end 34, a downstream, outlet end 36, and a series
of filtering flow passages (not shown) extending therethrough.
Exhaust gas 11 entering the rigid canister 30 through inlet 32
flows through the filter structure 26 from the upstream, inlet end
34 through the filtering passages, where it deposits particulate
matter suspended therein, and exits the downstream outlet end
36.
[0017] Due to various flow characteristics of the exhaust gas 11
caused by the sometimes conical shaped inlet of the canister 30, as
well as convective heat transfer from the outside surface 38 of the
rigid canister 30, the temperature profile of the ceramic wall-flow
filter 26 varies across its cross-section with higher temperatures
being measured towards a center zone 40, FIG. 3, of the filter and
lower temperatures are measured near a perimeter zone 42. This
temperature variation or differential may be pronounced during
regeneration of the PF device 24 when exhaust gas 11 has been
heated prior to entering the ceramic wall-flow filter 26 in order
to initiate combustion of the trapped particulates that are stored
thereon. During a regeneration event, heat transfer from the
outside surface 38 of the rigid canister 30 (i.e. radiant,
convection and conduction), as well as through the flow mechanism
of the exhaust gas 11 passing through the PF device, is relied on
to maintain the temperature of the filter 26 within an acceptable
range of operation.
[0018] Should the flow of exhaust gas 11 be reduced by an event
such as a sudden reduction of the engine speed to idle temperatures
in the filter 26, especially in the center flow zone 40, may exceed
those which are desirable for satisfactory performance of the PF
device 24. Such an excessive thermal gradient may cause the ceramic
wall-flow filter 26 to crack due to uneven expansion of the
material. To address temperature excursions of the center flow zone
40 of the ceramic wall-flow filter 26, a center zone conduit 44 is
in sealing, fluid contact with the downstream, outlet end 36 of the
filter in a configuration that divides the outlet end of the filter
into the aforementioned center flow zone 40 and a perimeter flow
zone 42. The upstream, inlet end 43 of the center zone conduit 44
may be inset into the filter media FIG. 2, or a ring or cup seal
(not shown) may be located about the perimeter of the upstream,
inlet end 43 and configured define a seal between the center zone
conduit 44 and the downstream, outlet end 36 of the ceramic
wall-flow filter 26. The seal may be constructed from a high
temperature flexible material such as graphite or other similar
material that can compress with the expansion of the particulate
filter and the cup. It should be noted that the manner of sealing
may have any suitable structure that enables system 10 to function
as described herein.
[0019] Exhaust gas 11 flowing through the ceramic wall-flow filter
26 from the upstream, inlet end 34 to the downstream, outlet end 36
exits the filter from either i) the center zone 40 and into the
center zone conduit 44 for transport further downstream in the
exhaust gas treatment system 10 or ii) the perimeter zone 42 and
back into the canister 30 for transport further downstream in the
exhaust gas treatment system 10. A flow control valve assembly 46
is disposed in the center zone conduit 44 and is operable between
an open and a closed position. Temperature sensors 47 may be
positioned at one or more positions across the downstream, outlet
end 36 of the filter 26, or within the filter, FIG. 1, to allow a
controller 48 in signal communication therewith to monitor the
temperature profile of the filter. Upon a determination that the
temperature of the exhaust flow in center zone 40 of the ceramic
wall-flow filter 26 has risen above a predetermined level, the
controller 48 will drive the flow control valve assembly 46 to a
closed position to thereby stop or restrict the flow of exhaust gas
11 through the center zone 40 of the filter 26. While a reduction
or a complete cessation of exhaust flow may appear
counterintuitive, such an action reduces or eliminates the
introduction of oxygen to the center zone 40 of the filter 26
resulting in extinguishing of the regeneration event and a rapid
reduction of the temperature in that portion of the ceramic
wall-flow filter 26.
[0020] Once the temperature of the center zone 40 has dropped below
a predetermined level, as measured by the temperature sensor(s) 47,
the controller 48 will drive the flow control valve assembly 46 to
an open position to thereby resume the flow of exhaust gas 11
through the center zone 40 of the filter 26 of the PF device 24. It
should be noted that in an exemplary embodiment, the exhaust flow
11 through the center zone conduit 44 is rejoined with the exhaust
flow 11 from the perimeter zone prior to exiting the rigid canister
30 at canister outlet 50. In an exemplary embodiment, the flow
control valve assembly 46 may include a plurality of valves
positioned in the center zone conduit 44 and the perimeter zone 42.
In certain cases it may be useful to restrict the flow of exhaust
gas 11 through the perimeter zone 42 so as to increase the flow
through, and therefore the heat transfer out of, the center zone 40
of the filter 26.
[0021] While the invention has been described with reference to a
center zone conduit 44 and flow control valve assembly 46 located
in downstream relationship to a ceramic wall-flow filter 26
disposed in a PF device 24, it is contemplated that the flow
control may take place upstream of the filter in embodiments of the
invention. In such a variation of the invention it is contemplated
that the center zone conduit 44 and flow control valve assembly 46
will be located in a similar relationship to the upstream, inlet
end 34 of the filter 26 and will regulate exhaust gas flow 11
through the filter 26 in a similar manner to that already
described.
[0022] 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 of 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 embodiments disclosed, but that the invention will
include all embodiments falling within the scope of the
application.
* * * * *