U.S. patent application number 12/545124 was filed with the patent office on 2011-02-24 for method of controlling fuel in an exhaust treatment system implementing temporary engine control.
This patent application is currently assigned to Caterpillar Inc.. Invention is credited to Dave Kapparos.
Application Number | 20110041483 12/545124 |
Document ID | / |
Family ID | 43495608 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110041483 |
Kind Code |
A1 |
Kapparos; Dave |
February 24, 2011 |
METHOD OF CONTROLLING FUEL IN AN EXHAUST TREATMENT SYSTEM
IMPLEMENTING TEMPORARY ENGINE CONTROL
Abstract
An exhaust treatment system associated with a power source is
disclosed. The exhaust treatment system may have a filter located
to remove particulate matter from a flow of exhaust, and a
regeneration device located proximal the filter. The exhaust
treatment system may also have a first fluid handling component
located upstream of the power source to vary an amount of oxygen in
the flow of exhaust, a second fluid handling component located
downstream of the power source to vary the amount of exhaust air
flow in the exhaust circuit, and a controller in communication with
the regeneration device and the fluid handling component. The
controller may determine a need for filter regeneration, and
determine adjustments to the first and second fluid handling
components required to provide sufficient oxygen and air mass flow
in the exhaust for filter regeneration. The controller may further
determine an effect the adjustments will have on operation of the
power source, and determine corrections for the power source to
account for the effects. The controller may substantially
simultaneously implement the adjustments and the corrections.
Inventors: |
Kapparos; Dave; (Janesville,
IA) |
Correspondence
Address: |
Caterpillar Inc.;Intellectual Property Dept.
AH 9510, 100 N.E. Adams Street
PEORIA
IL
61629-9510
US
|
Assignee: |
Caterpillar Inc.
Peoria
IL
|
Family ID: |
43495608 |
Appl. No.: |
12/545124 |
Filed: |
August 21, 2009 |
Current U.S.
Class: |
60/288 ;
60/295 |
Current CPC
Class: |
F02M 26/15 20160201;
Y02T 10/12 20130101; F01N 3/029 20130101; F01N 3/0842 20130101;
F02B 37/16 20130101; Y02T 10/144 20130101; F02B 37/013 20130101;
F01N 3/0256 20130101; F01N 2410/04 20130101; F01N 3/032 20130101;
F01N 3/0253 20130101; F02B 37/183 20130101 |
Class at
Publication: |
60/288 ;
60/295 |
International
Class: |
F01N 9/00 20060101
F01N009/00; F01N 3/023 20060101 F01N003/023 |
Claims
1. An exhaust treatment system associated with a power source,
comprising: a filter located downstream of the power source to
remove particulate matter from a flow of exhaust produced by the
power source; a regeneration device located proximal the filter to
raise a temperature of the removed particulate matter above an
ignition threshold; a first fluid handling component located
upstream of the power source to vary an amount of oxygen in the
flow of exhaust; a second fluid handling component located
downstream of the power source and upstream of the regeneration
device to vary the flow of exhaust bypassing the regeneration
device; and a controller in communication with the power source,
filter, regeneration device, first fluid handling component, and
second fluid handling component, the controller being configured
to: determine a need for filter regeneration; determine a first
adjustment to the first fluid handling component to provide
sufficient oxygen in the exhaust flow for filter regeneration;
determine a second adjustment to the second fluid handling
component to provide sufficient mass flow in the exhaust bypassing
the regeneration device; and facilitate the regeneration of the
filter.
2. The exhaust treatment system of claim 1, wherein the
regeneration device is a fuel-fired burner.
3. The exhaust treatment system of claim 1, wherein the first fluid
handling component is an induction valve configured to regulate the
flow of atmospheric air to the power source.
4. The exhaust treatment system of claim 3, wherein the first
adjustment is an increase in the amount of atmospheric air directed
to the power source.
5. The exhaust treatment system of claim 1, wherein the first fluid
handling component is a bypass valve configured to divert charged
air around the power source to the exhaust flow.
6. The exhaust treatment system of claim 5, wherein the first
adjustment is an increase in an amount of the charged air directed
around the power source to the exhaust flow.
7. The exhaust treatment system of claim 1, wherein the second
fluid handling component is a valve configured to divert exhaust
flow around the regeneration device to an intake of the power
source.
8. The exhaust treatment system of claim 7, wherein the second
adjustment is an increase in the amount of exhaust flow diverted
around the regeneration device to the intake of the power
source.
9. A method regenerating a filter that removes particulate matter
from a flow of exhaust produced by a power source, comprising:
combusting a fuel and air mixture to generate power and a flow of
exhaust; using a filter to remove and collect particulate matter
from the flow of exhaust; determining a need for a regeneration
device to regenerate the filter; determining a first adjustment in
the amount of oxygen to required for the regeneration device to
regenerate the filter; determining a second adjustment in the flow
of exhaust bypassing the regeneration device; and regenerating the
filter.
10. The method of claim 9, wherein the first adjustment is an
increase in the amount of atmospheric air directed to the power
source.
11. The method of claim 9, wherein the first adjustment is an
increase in an amount of charged air directed around the power
source to the exhaust flow.
12. The method of claim 9, wherein the second adjustment is an
increase in the amount of exhaust flow diverted around the
regeneration device to the intake of the power source.
13. An engine system, comprising: an engine configured to combust a
fuel and air mixture to generate power and a flow of exhaust; a
charged air induction circuit configured to introduce compressed
air into the engine; an exhaust circuit configured to direct the
flow of exhaust from the engine to the atmosphere; a filter located
downstream of the engine to remove particulate matter from the flow
of exhaust; a regeneration device located proximal the filter to
raise a temperature of the removed particulate matter above an
ignition threshold; a first valve located upstream of the engine to
vary an amount of oxygen in the flow of exhaust; a second valve
located downstream of the engine and upstream of the regeneration
device to vary the flow of exhaust bypassing the regeneration
device; and a controller in communication with the engine, filter,
regeneration device, first valve and second valve, the controller
being configured to: determine a need for particulate filter
regeneration; determine a first adjustment to the first valve
regulating oxygen in the exhaust flow for filter regeneration;
determine a second adjustment to the second valve regulating
exhaust flow bypassing the regeneration device; and facilitate the
regeneration of the filter.
14. The engine system of claim 13, wherein the regeneration device
is a fuel-fired burner.
15. The engine system of claim 13, wherein the first valve is an
induction valve configured to regulate the flow of atmospheric air
to the engine.
16. The engine system of claim 15, wherein the first adjustment is
an increase in the amount of atmospheric air directed to the power
source.
17. The engine system of claim 13, wherein the first valve is a
bypass valve configured to divert charged air around the power
source to the exhaust flow.
18. The engine system of claim 17, wherein the first adjustment is
an increase in an amount of charged air directed around the power
source to the exhaust flow.
19. The engine system of claim 13, wherein the second valve is a
valve configured to divert exhaust flow around the regeneration
device to an intake of the engine.
20. The engine system of claim 19, wherein the second adjustment is
an increase in the amount of exhaust flow diverted around the
regeneration device to the intake of the power source.
Description
TECHNICAL FIELD
[0001] The present disclosure relates generally to an exhaust
treatment system and, more particularly, to a method of controlling
fuel in an exhaust treatment system that implements temporary
engine control.
BACKGROUND
[0002] Engines, including diesel engines, gasoline engines, natural
gas engines, and other engines known in the art, exhaust a complex
mixture of air pollutants. The air pollutants may be composed of
gaseous and solid material, which include nitrous oxides (NOx) and
particulate matter. Due to increased attention on the environment,
exhaust emission standards have become more stringent and the
amount of NOx and particulate matter emitted from an engine may be
regulated depending on the type of engine, size of engine, and/or
class of engine.
[0003] One method that has been implemented by engine manufacturers
to comply with the regulation of NOx exhausted to the environment
has been to recirculate exhaust gas from an engine back into the
engine for subsequent combustion. The recirculated exhaust gas
reduces the concentration of oxygen in the intake air supplied to
the engine, which in turn lowers the maximum combustion temperature
within cylinders of the engine. The reduced temperature slows the
chemical process associated with combustion and, thereby, decreases
the formation of NOx.
[0004] A method used by engine manufacturers to reduce the amount
of particulate matter emitted to the environment includes removing
the particulate matter from the exhaust flow of an engine with a
device called a particulate filter. A particulate filter is
designed to trap particulate matter and typically consists of a
wire mesh or ceramic honeycomb filtration medium. Although
efficient at removing particulate matter from an exhaust flow, the
use of the particulate filter for extended periods of time may
cause the particulate matter to build up in the filtration medium,
thereby reducing the functionality of the filter and subsequent
engine performance. The collected particulate matter may be removed
from the filtration medium through a process called regeneration.
To initiate regeneration of the filtration medium, the temperature
of the particulate matter entrained within the filtration medium
must be elevated to a combustion threshold, at which the
particulate matter is burned away in the presence of oxygen.
[0005] Although the recirculation of exhaust gas and the use of a
particulate filter may minimize the discharge of NOx and
particulate matter to the atmosphere, both methods may affect or be
affected by the amount of oxygen entering and leaving the engine.
Specifically, exhaust gas recirculation (EGR) works by lowering the
amount of oxygen entering the engine and available for combustion.
Regeneration of the particulate filter requires oxygen to
facilitate the burning away of trapped particulate matter. Thus,
when EGR is operational, regeneration of the particulate filter may
be only minimally effective, as the amount of oxygen available for
regeneration is reduced by the use of EGR. For this reason, in some
applications, the two exhaust treatment methods may be mutually
exclusive or require additional or dedicated sources of oxygen for
regeneration purposes.
[0006] One attempt at using both EGR and particulate
trapping/regeneration in the same engine system is described in
U.S. Patent Publication No. 2002/50,150,218 (the '218 publication),
by Crawley et al. published on Jul. 14, 2005. Specifically, the
'218 publication describes an engine having an exhaust gas
recirculation system and an emission abatement assembly. The
emission abatement assembly includes a fuel-fired burner located
upstream of a particulate filter to regenerate the particulate
filter. During operation of the engine, exhaust gas flows through
the particulate filter, thereby trapping soot (i.e., particulate
matter) in the filter. The treated exhaust gas is then released
into the atmosphere through an exhaust pipe. From time to time
during operation of the engine, a control unit selectively operates
the fuel-fired burner to regenerate the particulate filter. In one
configuration, the emission abatement assembly does not utilize
supplemental air. As such, the position of an EGR valve is
coordinated with the regeneration of the particulate filter. That
is, to increase both the temperature and the oxygen content in the
exhaust gas, the engine's EGR valve is momentarily closed for a
period of about ten minutes. During this period of time, the
fuel-fired burner, being provided with a flow of fuel and
sufficient oxygen in the exhaust, is actuated to heat and thereby
regenerate the particulate filter.
[0007] Although the engine of the '218 publication may utilize and
benefit from both an EGR system and a particulate filter, operation
of the associated engine may be non-compliant and/or sub-optimal
during regeneration. That is, because EGR is utilized to reduce NOx
emissions, by turning EGR off (i.e., by closing the EGR valve)
during particulate regeneration, the engine may discharge excessive
amounts of NOx during that time period. In addition, because
relative amounts of air and fuel entering and being combusted by
the engine change when the EGR valve closes, regeneration of the
particulate filter could negatively and/or unexpectedly affect
other aspects of engine performance (i.e., power output, fuel
consumption, etc.) during the regeneration period. Additionally,
during regeneration, large quantities of fuel are consumed as the
fuel-fired burner heats all of the exhaust gases coming from the
power source.
[0008] The disclosed exhaust treatment system is directed to
overcoming one or more of the problems set forth above.
SUMMARY OF THE INVENTION
[0009] In one aspect, the present disclosure is directed to an
exhaust treatment system associated with a power source. The
exhaust treatment system may include a filter located downstream of
the power source to remove particulate matter from a flow of
exhaust produced by the power source. The exhaust treatment system
may also include a regeneration device located proximal the filter
to raise a temperature of the removed particulate matter above an
ignition threshold. The exhaust treatment system may also include a
first fluid handling component located upstream of the power source
to vary an amount of oxygen in the flow of exhaust, and a second
fluid handling component located downstream of the power source and
upstream of the regeneration device to vary the flow of exhaust
bypassing the regeneration device. The exhaust treatment system may
also include a controller in communication with the power source,
filter, regeneration device, first fluid handling component, and
second fluid handling component. The controller may be configured
to determine a need for filter regeneration. The controller may
also be configured to determine a first adjustment to the first
fluid handling component to provide sufficient oxygen in the
exhaust flow for filter regeneration. Further, the controller may
also be configured to determine a second adjustment to the second
fluid handling component to provide sufficient mass flow in the
exhaust bypassing the regeneration device. The controller may also
facilitate the regeneration of the filter.
[0010] In another aspect, the present disclosure is directed to a
method for regenerating a filter that removes particulate matter
from a flow of exhaust produced by a power source. The method may
include the step of combusting a fuel and air mixture to generate
power and a flow of exhaust. The method uses a filter to remove and
collect particulate matter from the flow of exhaust. The need for
regeneration of the filter may be determined. Additionally,
adjustments in the amount of oxygen required for the regeneration
device to regenerate the filter may be determined. Adjustments in
the flow of exhaust bypassing the regeneration device may be
determined. The filter may then be regenerated.
[0011] In yet another aspect, the present disclosure is directed to
an engine system having an engine configured to combust a fuel and
air mixture to generate power and a flow of exhaust. The engine
system may also have a charged air induction circuit configured to
introduce compressed air into the engine. The system may also have
an exhaust circuit configured to direct the flow of exhaust from
the engine to the atmosphere. Further, the system may have a filter
located downstream of the engine to remove particulate matter from
the flow of exhaust. The system may also include a regeneration
device located proximal the filter to raise a temperature of the
removed particulate matter above an ignition threshold. A first
valve may be located upstream of the engine to vary an amount of
oxygen in the flow of exhaust. A second valve may also be located
downstream of the engine and upstream of the regeneration device to
vary the flow of exhaust bypassing the regeneration device. The
system may also include a controller in communication with the
engine, filter, regeneration device, first valve and second valve.
The controller may be configured to determine a need for
particulate filter regeneration. The controller may also determine
a first adjustment to the first valve regulating oxygen in the
exhaust flow for filter regeneration. The controller may also
determine a second adjustment to the second valve regulating
exhaust flow bypassing the regeneration device. Further, the
controller may also facilitate the regeneration of the filter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a diagrammatic illustration of a power source
having an exemplary disclosed exhaust treatment system.
DETAILED DESCRIPTION
[0013] FIG. 1 illustrates a power source 10 having an exemplary
exhaust treatment system 12. Power source 10 may embody an engine
such as, for example, a diesel engine, a gasoline engine, a gaseous
fuel-powered engine such as a natural gas engine, or any other
engine apparent to one skilled in the art. Power source 10 may
alternatively embody a non-engine source of power such as a
furnace. Exhaust treatment system 12 may include an air induction
circuit 14, an exhaust circuit 16, and a recirculation circuit 18
coupled to power source 10 to transfer fluids into and out of power
source 10.
[0014] Air induction circuit 14 may include a means for introducing
charged air into a combustion chamber (not shown) of power source
10. For example, air induction circuit 14 may include an air
cleaner 20 and an induction valve 22 fluidly coupled upstream of
one or more compressors 24. It is contemplated that additional
and/or different components may be included within air induction
circuit 14 such as, for example, one or more air coolers located
upstream and/or downstream of compressors 24, a waste gate
associated with pressure relief of compressors 24, and other means
known in the art for introducing charged air into the combustion
chambers of power source 10.
[0015] Induction valve 22 may regulate the flow of atmospheric air
from cleaner 20 to compressors 24. Induction valve 22 may include,
for example, a butterfly element, a shutter element, a gate
element, a ball element, a globe element, or any other type of
valve element known in the art. The element of induction valve 22
may be disposed within a passageway 28 and be movable from a flow
passing position against a spring bias toward a flow restricting
position. In one example, the element of induction valve 22 may be
connected to a torsional spring (not shown) that may bias the
element toward the flow restricting position. When in the flow
passing position, atmospheric air may be directed from cleaner 20
through compressors 24 into power source 10 substantially
unrestricted. The element of induction valve 22 may be moved to any
position between the flow restricting and flow passing positions in
response to one or more input.
[0016] Compressors 24 may be disposed in a series relationship and
fluidly connected to power source 10 to compress the air flowing
into power source 10 to a predetermined level. Each of compressors
24 may embody a fixed geometry compressor, a variable geometry
compressor, or any other type of compressor known in the art. It is
contemplated that compressors 24 may alternatively be disposed in a
parallel relationship or that air induction circuit 14 may include
only a single compressor 24. It is further contemplated that
compressors 24 may be omitted, when a non-pressurized air induction
circuit is desired.
[0017] Exhaust circuit 16 may include a means for treating and
directing exhaust flow out of power source 10. For example, exhaust
circuit 16 may include one or more turbines 32 connected to receive
exhaust from power source 10 in a series relationship, a
particulate filter 42 located downstream of turbines 32, and a NOx
absorber 43 located downstream of particulate filter 42. It is
contemplated that exhaust circuit 16 may include additional and/or
different components such as, for example, catalyzed emission
controlling devices, attenuation devices, and other means known in
the art for treating and directing exhaust flow out of power source
10.
[0018] Each turbine 32 may be connected to one compressor 24 to
drive the connected compressor 24. In particular, as the hot
exhaust gases exiting power source 10 expand against blades (not
shown) of turbine 32, turbine 32 may rotate and drive the connected
compressor 24. It is contemplated that turbines 32 may
alternatively be disposed in a parallel relationship or that only a
single turbine 32 may be included within exhaust circuit 16. It is
also contemplated that turbines 32 may be omitted and compressors
24 may be driven by power source 10 mechanically, hydraulically,
electrically, or in any other manner known in the art, if
desired.
[0019] Particulate filter 42 may be disposed downstream of turbines
32 to remove particulates from the exhaust flow of power source 10.
It is contemplated that particulate filter 42 may include
electrically conductive or non-conductive coarse mesh metallic or
ceramic elements. It is also contemplated that particulate filter
42 may include a catalyst (not shown) for reducing an ignition
temperature of the particulate matter trapped by particulate filter
42, a means 45 for regenerating the particulate matter trapped by
particulate filter 42, or both a catalyst and a means for
regenerating. The catalyst may support the reduction of HC, CO,
and/or particulate matter, and may include, for example, a base
metal oxide, a molten salt, and/or a precious metal. The means 45
for regenerating may include, among other things, a fuel-fired
burner 47, an electrically-resistive heater, an engine control
strategy, or any other suitable means for regenerating. It is
further contemplated that particulate filter 42 may be relocated
elsewhere within recirculation circuit 18, if desired.
[0020] NOx absorber 43 may include one or more substrates coated
with or otherwise containing a liquid or gaseous catalyst such as,
for example, a precious metal-containing washcoat. The catalyst may
be utilized to reduce the byproducts of combustion in the exhaust
flow by means of selective catalytic reduction (SCR) or NOx
trapping. In one example, a reagent such as urea may be injected
into the exhaust flow upstream of NOx absorber 43. The urea may
decompose to ammonia, which reacts with NOx in the exhaust to form
H.sub.2O and N.sub.2. In another example, NOx in the exhaust may be
trapped by a barium salt-containing device and be periodically
released and reduced across a catalyst to form CO.sub.2 and
N.sub.2. NOx absorber 43 may also be utilized to oxidize
particulate matter that remains in the exhaust flow after passing
through particulate filter 42, if desired.
[0021] A first bypass circuit 34 may be associated with air
induction circuit 14 and exhaust circuit 16 to selectively pass
charged air from compressor 24 around power source 10 to the means
45 for regenerating particulate filter 42. A bypass valve 36 may be
located within circuit 34 and include, for example, a butterfly
element, a shutter element, a gate element, a ball element, a globe
element, or any other type of valve element known in the art that
is movable to regulate the flow of charge air through bypass
circuit 34.
[0022] Recirculation circuit 18 may include a means for redirecting
a portion of the exhaust flow of power source 10 from exhaust
circuit 16 into air induction circuit 14. For example,
recirculation circuit 18 may include an inlet port 40, a
recirculation valve 46, and a discharge port 48. It is contemplated
that recirculation circuit 18 may include additional and/or
different components such as an exhaust cooler, a catalyst, an
electrostatic precipitation device, a shield gas system, and other
means known in the art for redirecting substantially
particulate-free exhaust from exhaust circuit 16 into induction
circuit 14. As a portion of the exhaust from exhaust circuit 16
enters recirculation circuit 18 via inlet port 40, the exhaust may
be restricted to a desired flow rate by recirculation valve 46, and
directed into induction circuit 14 via discharge port 48. Inlet
port 40 may be connected to exhaust circuit 16 to receive at least
a portion of the exhaust flow from power source 10. Specifically,
inlet port 40 may be disposed downstream of turbines 32 to receive
low-pressure exhaust gas from turbines 32.
[0023] A second bypass circuit 76 may be associated with
recirculation circuit 18 to selectively pass at least a portion of
exhaust gas from power source 10 around exhaust circuit 16;
downstream of particulate filter 42; and into the inlet port 40 of
recirculation circuit 18. A bypass valve 78 may be located within
bypass circuit 76, and include, for example, a two-way or three-way
valve including a butterfly element, a shutter element, a gate
element, a ball element, a globe element, or any other type of
valve element known in the art. The bypass valve may be located
adjacent and downstream of the power source 10. Further, bypass
valve 76 may be located upstream of fuel fired burner 47.
[0024] Recirculation valve 46 may be fluidly connected to inlet
port 40 via a fluid passageway 52, and to discharge port 48 via a
fluid passageway 54. In this manner, recirculation valve 46 may be
situated to selectively pass or restrict the flow of exhaust from
exhaust circuit 16 into air induction circuit 14.
[0025] Discharge port 48 may be fluidly connected to recirculation
valve 46 to direct the exhaust flow regulated by recirculation
valve 46 into air induction circuit 14. Specifically, discharge
port 48 may be connected to air induction circuit 14 upstream of
compressors 24, such that compressors 24 may draw the exhaust flow
from discharge port 48. In an alternative high pressure exhaust
recirculation circuit, it is contemplated that discharge port 48
may be located downstream of compressors 24, if desired.
[0026] A control system 62 may include components that interact to
determine and control operational characteristics of induction,
exhaust, and recirculation circuits 14, 16, 18. In particular,
control system 62 may include a controller 66 in communication with
air induction valve 22, bypass valve 36, recirculation valve 46,
the means 45 for regenerating particulate filter 42, power source
10, bypass valve 78, via communication lines 68, 70, 72, 74, and 80
respectively. It is contemplated that additional sensors such as,
for example, an engine speed sensor, an exhaust temperature or
oxygen sensor, an intake air pressure or temperature sensor, a fuel
flow or pressure sensor, a NOx sensor, or any other type of sensor
known in the art, may also be included within control system 62 and
in communication with controller 66, if desired.
[0027] Controller 66 may embody a single microprocessor or multiple
microprocessors that include a means for controlling an operation
of induction, exhaust, and recirculation circuits 14, 16, 18, and
power source 10. Numerous commercially available microprocessors
can be configured to perform the functions of controller 66. It
should be appreciated that controller 66 could readily embody a
general power source microprocessor capable of controlling numerous
engine functions. Controller 66 may include a memory, a secondary
storage device, a processor, and other components for running an
application. Various other circuits may be associated with
controller 66 such as power supply circuitry, signal conditioning
circuitry, solenoid driver circuitry, and other types of
circuitry.
[0028] One or more maps relating an exhaust oxygen concentration, a
boost pressure, an intake air temperature, an intake air flow rate,
an engine fuel injection amount, an injection timing, an injection
pressure, an engine power output, exhaust air flow rate, exhaust
emission level, and/or a required setting or configuration of a
first and second fluid handling component may be stored in the
memory of controller 66. Each of these maps may be a collection of
data in the form of tables, graphs, and/or equations.
[0029] Controller 66 may receive input indicative of a need for
particulate filter regeneration, and reference the maps described
above to determine an adjustment to a first fluid handling
component (i.e., induction valve 22, compressor 24, bypass valve
36, recirculation valve 46, etc.) required to provide oxygen in the
exhaust flow sufficient to facilitate the regeneration event. That
is, in order to achieve an appropriate temperature for regenerating
particulate filter 42, a sufficient supply of oxygen must be
present to properly combust the fuel injected by burner 47.
Controller 66 may further reference the described maps to determine
an adjustment to a second fluid handling component (i.e., bypass
valve 78, recirculation valve 46, etc.) required to provide the
minimum exhaust air flow rate to facilitate the regeneration
event.
[0030] Thus, in response to the indicated need for regeneration,
controller 66 may reference the maps to determine an increased
opening amount of induction valve 22 (i.e., a decreased restriction
of induction valve 22) that allows more oxygen to enter and pass
through power source 10 to burner 47, a change in a compressor
characteristic that increases a pressure and/or a flow rate of air
entering and passing through power source 10, an increased opening
of bypass valve 36 that amplifies an amount of air diverted
directly to the exhaust downstream of power source 10, and/or a
decreased opening of recirculation valve 46 (i.e., an increased
restriction on the exhaust being recirculated to air induction
circuit 14) such that the concentration of oxygen entering and
leaving power source 10 increases. Further, in response to the
indicated need for regeneration, controller 66 may reference maps
to determine an increased restriction in bypass valve 78 that
reduces the exhaust air flow rate in exhaust circuit 16 (i.e.,
increases the exhaust air flow rate in bypass circuit 76), and/or a
increased opening of recirculation valve 46 (i.e., a decreased
restriction on the exhaust being recirculated to air induction
circuit 14) such that the mass flow rate of air being delivered to
burner 47 is reduced. The need for regeneration may be based on an
elapsed period of time, a pressure or temperature of the exhaust
measured or predicted upstream of particulate filter 42, a
differential pressure measured or predicted across particulate
filter 42, a calculated amount of soot loading, or other similar
parameter. It is contemplated that controller 66 may resolve
conflicts between the aforementioned maps to optimize oxygen and
exhaust air flow rates in order to achieve regeneration of
particulate filter 42 in a manner that reduces energy and fuel
costs.
[0031] Controller 66 may also be configured to determine a
correction to the operation of power source 10 that is necessary to
account for the adjustment(s) made to the fluid handling
components. Specifically, when adjusting the opening amount of air
induction valve 22, changing a characteristic of compressor 24 to
increase a pressure and/or flow rate of air entering power source
10, increasing an opening of bypass valve 36, and/or decreasing an
opening of recirculation valve 46, the air-to-fuel ratio of power
source 10 may change significantly. For example, when air induction
valve 22 is opened to a greater extent, the configuration or
performance of compressor 24 is changed to increase boost pressure
and/or intake air flow, or recirculation valve 46 is closed a
greater amount, the air-to-fuel ratio of power source 10 may
increase. In contrast, when bypass valve 36 is opened to a greater
amount, the air-to-fuel ratio of power source 10 may decrease. As
such, the power output, operating temperatures, exhaust emission
levels, fuel consumption, and other performance factors of power
source 10 may be affected. And, in order to continue providing a
demanded power output, ensure operation of power source 10 remains
within design guidelines, the emissions of power source 10 remain
compliant with government regulations, and the general performance
of power source 10 remains acceptable to an operator thereof,
characteristics of power source 10 may require some correction
during the regeneration event. Some of these characteristics may
include, among other things, a fueling characteristic (injection
amount, pressure, number and/or distribution of injection shots,
injection timing, etc) and an air induction characteristic (boost
pressure, engine valve timing, etc.). Controller 66 may determine
what correction may be required to maintain consistent or even
improve power source operation during the regeneration event (i.e.,
during the time period when the operational characteristics of
exhaust and recirculation circuits 16, 18 are being adjusted to
accommodate a regeneration of particulate filter 42).
[0032] Controller 66 may implement both the adjustment(s) required
for particulate filter regeneration and the power source
operational correction(s) substantially simultaneously. That is,
once controller 66 has determined the required adjustment(s) and
the required correction(s), both the adjustment(s) and
correction(s) may be implemented such that the performance of power
source 10 remains substantially within or enters a desired
performance range during the regeneration event. For the purposes
of this disclosure, the term "substantially simultaneously" may
refer to a predetermined time period during which multiple actions
are performed by controller 66 such as, for example, when
controller 66 implements the adjustment(s) and the correction(s)
with a few seconds (or less) of each other.
INDUSTRIAL APPLICABILITY
[0033] The disclosed exhaust treatment system may be applicable to
any combustion-type device such as, for example, an engine, a
furnace, or any other combustion device known in the art where a
particulate filter regeneration event may affect performance of the
combustion-type device. The disclosed treatment system may maintain
consistent or even improve performance of the combustion-type
device during the regeneration event, by anticipating a change in
air-to-fuel ratio of the device during the event, determining an
affect the change will have on the device, and correcting
operational characteristics of the device during the event to
accommodate the affect. The operation of exhaust treatment system
12 will now be explained.
[0034] Atmospheric air may be drawn into air induction circuit 14
via induction valve 22 and directed through compressors 24 where it
may be pressurized to a predetermined level before entering the
combustion chamber of power source 10. Fuel may be mixed with the
pressurized air before or after entering the combustion chamber of
power source 10, and then be combusted by power source 10 to
produce mechanical work and an exhaust flow containing gaseous
compounds and solid particulate matter. The exhaust flow may be
directed from power source 10 to turbines 32 where the expansion of
hot exhaust gases may cause turbines 32 to rotate, thereby rotating
connected compressors 24 to compress the inlet air. After exiting
turbines 32 and flowing through particulate filter 42, the exhaust
gas flow may be divided into two substantially particulate-free
flows, including a first flow redirected to air induction circuit
14 and a second flow directed to the atmosphere.
[0035] The flow of the reduced-particulate exhaust directed through
inlet port 40 may be drawn via recirculation valve 46 back into air
induction circuit 14 by compressors 24. The controlled restriction
of exhaust by recirculation valve 46 may affect the amount of
exhaust drawn by compressors 24 through air induction circuit 14 to
power source 10.
[0036] The recirculated exhaust flow may then be mixed with the air
entering the combustion chambers. The exhaust gas, which is
directed to the combustion chambers of power source 10, may reduce
the concentration of oxygen therein, which in turn lowers the
maximum combustion temperature within power source 10. The lowered
maximum combustion temperature may slow the chemical reaction of
the combustion process, thereby decreasing the formation of nitrous
oxides. In this manner, the gaseous pollution produced by power
source 10 may be reduced without experiencing the harmful effects
and poor performance caused by excessive particulate matter being
directed into power source 10. As the second flow of exhaust passes
inlet port 40, it may be directed through a catalyst to remove NOx
and other pollutants from the exhaust.
[0037] After a period of power source operation, the buildup of
particulate matter in particulate filter 42 may be significant and
require regeneration. To regenerate particulate filter 42,
fuel-fired burner 47 may inject an amount of fuel into the exhaust
stream of power source 10 upstream of particulate filter 42. To
ensure efficient burning of the injected fuel and complete
regeneration of particulate filter 42, a sufficient concentration
of oxygen must be present in the exhaust flow. The oxygen may be
supplied in at least two ways, including directly from compressor
24 via bypass circuit 34, or indirectly from compressor 24 via
power source 10.
[0038] To directly increase the concentration of oxygen in the
exhaust from power source 10, bypass valve 36 may be moved to
reduce a restriction on the flow of charged air passing through
bypass circuit 34. The amount of air passing through circuit 34 may
be sufficient to regenerate particulate filter 42, and regulated by
controller 66, as described above. However, by allowing a greater
amount of air to pass through circuit 34, less air may be available
for combustion within power source 10 (i.e., the air-to-fuel ratio
may decrease), if the adjustment of bypass valve 36 is unaccounted
for. A lower air-to-fuel ratio may increase exhaust temperatures
and emissions of power source 10, while simultaneously reducing a
power output and fuel efficiency thereof.
[0039] To minimize the affect that the adjustment of bypass valve
36 may have on the performance of power source 10, various
operational characteristics of power source 10 may be corrected.
For example, the boost pressure and/or flow rate of air at an inlet
of power source 10 may be increased. This increase may be
accomplished by correcting an operation of compressor 24,
correcting a wastegate setting, and/or correcting an engine valve
setting (i.e. an engine opening, closing, lift height, and/or lift
duration) during the regeneration event. To minimize performance
interruption of power source 10, the adjustment to bypass valve 36
and the correction of power source 10 may be implemented
substantially simultaneously.
[0040] To indirectly increase the concentration of oxygen in the
exhaust from power source 10, recirculation valve 46 may be moved
to increase a restriction on the flow of exhaust passing into power
source 10. By increasing the exhaust restriction, a greater amount
of fresh air may be forced/drawn into power source 10 such that the
concentration of oxygen in the exhaust exiting power source 10 may
be sufficient to regenerate particulate filter 42. As above, the
movement of exhaust recirculation valve 46 may be regulated by
controller 66. However, by reducing the amount of exhaust
recirculated through power source 10, the production of NOx may
increase, if the adjustment of recirculation valve 46 is
unaccounted for. An increased production of NOx may cause power
source 10 to be noncompliant with government regulations.
[0041] To minimize the affect that the adjustment of recirculation
valve 46 may have on the performance of power source 10 (i.e., on
the production of NOx), various operational characteristics of
power source 10 may be corrected. For example, an amount of fuel
injected into power source 10, a timing of the injections, and/or a
distribution of the injections may be adjusted to minimize the
production of NOx during the regeneration event. These changes in
the fuel injection profile may be implemented via controller
regulation of a power source fuel system. To minimize performance
interruption of power source 10, the adjustment to recirculation
valve 46 and the correction of power source 10 may be implemented
substantially simultaneously. Similar adjustments and corrections
can be made in association with other fluid handling
components.
[0042] In addition to regulating the requisite amount of oxygen
necessary to perform a regeneration. During a regeneration event,
the controller 66 also may optimize the amount of exhaust air mass
flow that is delivered from power source 10 to regeneration means
45, which is shown as burner 47. During a regeneration event
controller 66 may directly reduce the amount of exhaust air mass
flow that is directed to the burner 47. Bypass valve 78 may be
moved to increase a restriction on the flow of exhaust air that is
provided to the burner 47. In so doing, at least a portion of
exhaust air is diverted around the burner and particulate filter.
The portion of exhaust air that is diverted around the exhaust
circuit 16 passes through bypass circuit 76 and into regeneration
circuit 18. By reducing the amount of exhaust air flow that is
provided to the exhaust circuit 16, regeneration means 45 has less
exhaust air to heat, thus lowering the amount of energy or fuel
required to regenerate particulate filter 42.
[0043] Because the disclosed exhaust treatment system may correct
power source operation in connection with control of associated
fluid handling components, a particulate filter regeneration event
may be accomplished without substantially affecting power source
performance. In particular, the disclosed exhaust treatment system
may ensure exhaust emission compliance and/or optimal engine
performance, even when a regeneration-required adjustment to a
fluid-handling component is made. In fact, because the power source
correction may be made substantially simultaneously with the
regeneration-required adjustment, little, if any, interruption in
the output of power source 10 may be observed.
[0044] It will be apparent to those skilled in the art that various
modifications and variations can be made to the disclosed exhaust
treatment system. Other embodiments will be apparent to those
skilled in the art from consideration of the specification and
practice of the disclosed particulate regeneration system. It is
intended that the specification and examples be considered as
exemplary only, with a true scope being indicated by the following
claims and their equivalents.
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