U.S. patent application number 15/565978 was filed with the patent office on 2018-03-01 for oxidation of engine generated particulate matter utilizing exhaust manifold gases.
The applicant listed for this patent is Illinois Valley Holding Company. Invention is credited to Brett Bailey.
Application Number | 20180058283 15/565978 |
Document ID | / |
Family ID | 55911057 |
Filed Date | 2018-03-01 |
United States Patent
Application |
20180058283 |
Kind Code |
A1 |
Bailey; Brett |
March 1, 2018 |
OXIDATION OF ENGINE GENERATED PARTICULATE MATTER UTILIZING EXHAUST
MANIFOLD GASES
Abstract
An improved system and method for treating exhaust emissions
from a combustion engine is provided. The system provides improved
arrangements for oxidizing particulate matter away from a
particulate filter by utilizing elevated temperature exhaust
manifold gases.
Inventors: |
Bailey; Brett; (Cape Coral,
FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Illinois Valley Holding Company |
Downers Grove |
IL |
US |
|
|
Family ID: |
55911057 |
Appl. No.: |
15/565978 |
Filed: |
April 13, 2016 |
PCT Filed: |
April 13, 2016 |
PCT NO: |
PCT/US2016/027233 |
371 Date: |
October 12, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62146957 |
Apr 13, 2015 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01N 3/0842 20130101;
Y02T 10/12 20130101; F01N 2240/26 20130101; Y02T 10/24 20130101;
F01N 2610/02 20130101; F01N 3/0233 20130101; F01N 3/027 20130101;
F01N 3/2066 20130101; F01N 13/10 20130101; F01N 3/035 20130101 |
International
Class: |
F01N 3/023 20060101
F01N003/023; F01N 3/027 20060101 F01N003/027; F01N 3/035 20060101
F01N003/035; F01N 13/10 20060101 F01N013/10; F01N 3/20 20060101
F01N003/20; F01N 3/08 20060101 F01N003/08 |
Claims
1. A system for oxidizing particulate matter of an engine, the
system comprising: a particulate matter oxidation system for
oxidizing particulate matter output from the engine; an exhaust
manifold in fluid communication with the particulate matter
oxidation system, wherein exhaust gases from the exhaust manifold
are used to oxidize particulate matter produced by the engine; a
settling tank in fluid communication with the exhaust manifold and
the particulate matter oxidation system; a particulate filter
downstream from the particulate matter oxidation system for
filtering particulate matter from at least one of the engine and
the particulate matter oxidation system.
2. The system of claim 1, wherein the particulate matter oxidation
system is a volume of the exhaust manifold.
3. The system of claim 1, wherein the system includes a heating
element for providing thermal energy to the particulate matter to
convert the particulate matter from at least one of a solid and
liquid phase to a gas phase gas capable of passing through the
particulate filter.
4. The system of claim 1, wherein particulate matter is transported
from the particulate filter to the particulate matter oxidation
system via a non-thermal regeneration system.
5. The system of claim 1, wherein the system includes a valve for
controlling flow out of the exhaust manifold into the settling
tank.
6. The system of claim 1, wherein the system includes an oxidation
catalyst coated to the particulate matter oxidation system.
7. The system of claim 3, wherein the system further includes a
high porosity filter between the heating element and an exhaust
pipe of the engine to trap and assist in oxidizing the particulate
matter.
8. The system of claim 7, wherein the system further includes a
second filter downstream from the high porosity filter for trapping
ash and preventing the ash from reentering a main engine filter of
the engine.
9. The system of claim 1, wherein the system further includes a
valve for controlling flow of high temperature manifold gases for
oxidizing the particulate matter.
10. The system of claim 1, wherein the system further includes an
electric control module to control the flow of manifold gases into
the particulate matter oxidation system.
11. A method for oxidizing particulate matter of an engine, the
method comprising the steps of: introducing particulate matter into
a particulate matter oxidation system for oxidizing particulate
matter output from the engine; venting exhaust gases from an
exhaust manifold in fluid communication with the particulate matter
oxidation system into the particulate matter oxidation system to
oxidize particulate matter produced by the engine; and filtering
particulate matter from at least one of the engine and the
particulate matter oxidation system via a particulate filter
downstream from the particulate matter oxidation system.
12. The method of claim 11, wherein the particulate matter
oxidation system is a volume of the exhaust manifold.
13. The method of claim 11, further including the step of providing
thermal energy to the particulate matter via a heating element to
convert the particulate matter from at least one of a solid and
liquid phase to a gas phase gas capable of passing through the
particulate filter.
14. The method of claim 11, wherein particulate matter is
transported from the particulate filter to the particulate matter
oxidation system via a non-thermal regeneration system.
15. The method of claim 11, further including the step of
controlling flow out of the exhaust manifold into a settling tank
via a valve.
16. The method of claim 11, wherein the particulate matter
oxidation system includes an oxidation catalyst coated thereto.
17. The method of claim 13, wherein a high porosity filter is
provided between the heating element and an exhaust pipe of the
engine to trap and assist in oxidizing the particulate matter.
18. The method of claim 17, wherein a second filter is provided
downstream from the high porosity filter for trapping ash and
preventing the ash from reentering a main engine filter of the
engine.
19. The method of claim 11, further including the step of
controlling flow of high temperature manifold gases via a valve for
oxidizing the particulate matter.
20. The method of claim 11, wherein an electric control module is
provided to control the flow of manifold gases into the particulate
matter oxidation system.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to engine exhaust
treatment. More particularly, the present invention relates to
improved arrangements for oxidizing particulate matter away from a
particulate filter by utilizing elevated temperature exhaust
manifold gases.
DISCUSSION OF PRIOR ART
[0002] Commercially available active diesel exhaust treatment
systems utilize a particulate filter which is passively, active
passively, or active high temperature thermally regenerated. In
those systems, particulate matter is removed by transforming the
particulate matter from a solid to a gas in the form of unburned
hydrocarbons (UHC), carbon monoxide (CO), and carbon dioxide (CO2),
or other potential, known gases. Oxidizing particulate matter into
the gas phase eliminates the inhalation problem presented to
humans, but it increases the amount of environmentally harmful
Green House Gases (GHG) emitted by the vehicle. Oxidizing
particulate matter into the gas phase also reduces the overall
thermal efficiency of an engine and/or vehicle.
[0003] Diesel fuel is a convenient source of energy for
regeneration. During active high temperature filter regeneration,
the exhaust gas temperature can be increased by combusting an
additional quantity of fuel in the exhaust system using specialized
hardware and using one of the following known methods: [0004] Late
injection combustion--Fuel is injected later in the expansion
stroke of the engine so that the lower effective compression ratio
produces high exhaust temperatures. [0005] Flame combustion--Fuel
is combusted in a fuel burner, usually with a dedicated supply of
combustion air, with the flame entering the exhaust system. [0006]
Catalytic combustion--Fuel is introduced through an exhaust
injector, evaporated and mixed with exhaust gas, and oxidized over
an oxidation catalyst. [0007] Combined flame and catalytic
combustion--A combination of the above methods, where a fuel burner
is followed by a catalytic combustion system. Further details can
be found in "Filters Regenerated by Fuel Combustion" by W. Addy
Majewski (Majewski, W. Addy. "Filters Regenerated by Fuel
Combustion." Diesel Technology Guide--Diesel Filter Systems.
Dieselnet, 2009. Web. 27 May 2010.
http://www.dieselnet.com/tech/dpf_sys_fuel.html). In the above
known methods, the removed particulate is burned. This process
creates CO2, which is subsequently released into the
atmosphere.
[0008] Catalytic oxidation of the fuel requires exhaust temperature
above the "light-oft" or operating temperature, of the oxidation
catalyst. Below the "light-off" temperature, the fuel would only
coat the oxidation catalyst, and the catalytic oxidation process
would not initiate. Engines that operate at low exhaust
temperatures for extended periods of time require special exhaust
or intake throttling, burners, or some other machine or method to
raise the temperature to the point that the oxidation catalyst
begins operation. Only then will oxidation catalyst regeneration be
initiated. The entire regeneration becomes a lengthy and costly
process.
[0009] U.S. Pat. No. 7,992,382 describes using a back flow of
filtered exhaust gases to regenerate the filter by routing filtered
particulate matter to a burner. The burner in this system utilizes
an electric heating element to oxidize the particulate matter being
removed from the engine. This arrangement is disadvantageous
because it creates high differential thermal gradients of
additional carbon dioxide beyond the particulate matter oxidation.
This is due to the engine's alternator acting as a parasitic load
requiring a substantial share of electrical energy.
[0010] While oxidation of the particulate matter, with electrical
energy alone, seems to be a simple solution when coupled with the
right controls and sensors, there are many technical challenges in
such systems. Controlling the temperature of the heating element to
ensure longevity of the sheathing from damage on every cycle is
particularly challenging, depending on the flowrates of exhaust gas
and particulate level entrained within the gases. An additional
technical challenge associated with electrical spiral burner
systems includes the substantial thermal capacity required by the
heating elements to maintain the temperatures sufficient to oxidize
the particulate matter passing through the burner.
[0011] In order to electrically regenerate filters for small
Auxiliary Power Units (APUs), some commercial systems heat the
filter while the APU engine is shutdown. This requires a blower to
provide the required oxygen, while also requiring a 160 amp
alternator, on the separate main propulsion engine, to provide the
energy require for regenerating the small wall flow filter. Other
systems take the generator offline from the main load requirements
to provide the unit's own power for regeneration. Both systems
require down or offline time for the regeneration to occur every
10-24 hours, depending on an APU's output load and emissions
output.
[0012] The advantage of utilizing a non-thermal active regeneration
technology is that the filter can be regenerated while the APU
engine is running and providing power to the cab. The oxidation of
the particulate matter can be conducted in a similar manner, but
with a proportionally smaller portion of the electrical energy.
This is because the time allowed for separate oxidation magnitudes
of time equivalent to the entire 10-24 hours of operation. The
oxidation of the particulate matter must be capable of oxidizing
the maximum amount of particulate generated at the engine's end of
life in the amount of time between non-thermal regenerations. If
the current system required 1.5 kW of power for 30 minutes, the
equivalent electrical energy required over 10 hours would equate to
a 70-watt source. The main advantage of reducing the electrical
energy required to a 70-watt source is that it can delivered by a
generator or the engine's own alternator.
[0013] Regeneration is not constrained by the upper temperature
limit of the filter substrate. Without this upper level temperature
constraint, the particulate can then be combusted at considerably
higher temperatures and subsequently diluted with additional air,
either via passive mixing in the settling tank or flow from
additional airflow from the dedicated pump as it passes back into
the exhaust system. In a manner similar to a Bunsen burner or
portable kerosene heater, the combustion of the particulate matter
can generate airflow of its own. Technical challenges for such a
system include feeding solid combustion particles into the
combustion zone.
[0014] The challenge for larger engines is that the large amount of
energy consumed often requires large controllers. Even using large
controllers, the energy consumed is still a significant amount of
energy. Also, the air pump for operating the exhaust backpressures
may require a positive displacement pump device. This adds to the
complexity, cost, and maintenance issues associated with the
systems, depending on the particulate filter's backpressure.
[0015] With a simple control strategy, electrical energy can be
generated in combination with a blower to oxidize the particulate
matter. The negatives of such a design are the needs for a blower
and using a portion of the main engine's electrical output load.
Other systems utilize electrically heated filter elements for
regeneration. For APUs this is the best currently known system
because the engine's exhaust temperature can be too low for
particulate regeneration or for oxidation catalyst light-off
temperatures. APU engines are typically naturally aspirated, so
their exhaust temperatures would require extensive amounts of
electrical energy in order to bring the exhaust gas temperature to
a high enough condition to achieve passive/active regeneration. As
set forth above, this requires the APU's generator to be dedicated
to the regeneration strategy.
[0016] Because it would wasteful to thermally regenerate the filter
after each shutdown, there is a high likelihood of the regeneration
being required during the driver's sleep pattern. The non-thermal
regeneration technology is independent of the engine/generator
operation, and thus the oxidation can be a fraction of the current
regeneration time and/or the naturally aspirated order to reduce
the electrical required for oxidation of the particulate matter
within the residence required, along with the high flow rates
requiring high thermal capacity. The oxidation rate of the
particulate matter may therefore be accomplished in between the
regenerations, and at all times the engine is operating. While some
systems utilize electrical energy to oxidize the particulate
matter, most systems use fuel to provide the regeneration high
temperatures.
[0017] In order to reduce the particulate exiting the tailpipe, the
current commercial state of the art engine technology has typically
included a Diesel Particulate Filter (DPF) to trap the particles in
the engine's exhaust before they are released into the atmosphere.
While particulate filters have been commercially available for
decades, the technology for removing the built up particulate
matter has had varying degrees of success. This, along with fuel
efficiency reductions caused by the filter restriction, has
required government regulations to be passed in order to improve
the technology's commercial availability.
[0018] The current solutions are overly complicated, require some
method of active regeneration, or require a high exhaust
temperature operating cycle. The active regeneration technologies
utilize additional fuel use for increasing exhaust temperature,
which does not provide useable output work. The use of fuel without
subsequent output work does not comply with the current global
concern for GHG, carbon dioxide, or end user concerns over high
fuel prices (e.g., operating costs). In addition to fuel, the
current systems require sophisticated controls algorithms, sensors,
burners, or dosing systems, and scarce, costly rare-earth
elements.
BRIEF SUMMARY OF THE PRESENT INVENTION
[0019] The present invention is directed to improved arrangements
in which particulate matter is oxidized away from the particulate
filter utilizing waste high temperature gases that are produced at
higher engine loads. Oxidizing particulate matter away from the
particulate filter removes the potential for damage caused by high
thermal gradients and subsequent thermal stress. Using high
temperature waste thermal energy by focusing the energy and excess
oxygen mass flow on the few grams of particulate matter simplifies
the oxidation and transition to the gas state.
[0020] While manifold gases can reach temperatures capable of
oxidizing the unburned hydrocarbons and even the elemental carbon
directly with oxygen, the use of a catalyst such as platinum or
palladium may increase efficiency by lowering the temperature of
oxidation with the use of NO.sub.2 as the oxidant. For thermal
challenged (e.g., low temperature applications) engines, an
electric heater or oxidation of fuel across a catalyst or burner
may be used to help manifold gases reach a sufficient
temperature.
[0021] The system is preferably advantageously utilized while under
high load in order to improve thermal efficiency. Even still, the
particulate matter may be regenerated at start up so as to increase
the preheat process or provide enhanced heating of the SCR
catalyst. Additionally, in at least one embodiment, urea may be
injected into the system in order to provide earlier conversion to
ammonia during a cold start operation.
Advantages of Present Invention
[0022] In accordance with the teachings of the present invention,
there is provided a stored particulate matter oxidation system
which preferably provides one or more of the following advantages,
all of which are provided by example alone: 1) Improves overall
thermal efficiency by utilizing waste high temperature exhaust
manifold gases for the oxidation of filtered particulate matter
waste; 2) Passive system does not require an ECM or control system,
thus reducing system cost and complexity; 3) Reduces electrical or
fuel energy required to oxidize the particulate matter by passive
NO.sub.2 and high temperature manifold gas assisted electrical
heating; 4) Increases thermal energy to the exhaust turbine; 5)
Reduces or eliminates requirement for close coupling the
aftertreatment to the engine for passive particulate matter
oxidation; 6) Reduces in frequency or eliminates thermal
regeneration of the particulate filter, thus improving safety and
substrate durability of the DPF, DPF/SCR combination and the
SCR/LNT catalyst; 7) Reduces fuel consumption; 8) Provides
potential for commercial availability of high engine particulate
matter designs; 9) Uses less expensive system than can be used in
the thermally regenerated systems which require sophisticated
hardware and control systems; 10) Eliminates need for oxidizing the
particulate on the main engine particulate filter which, by using
high temperature and subsequent thermal gradients, can damage the
filter, the intumescent wrap, and any downstream aftertreatment;
11) Reduces and possibly eliminates downtime required for forced
active regeneration and ash maintenance; 12) Reduces or eliminates
the need for a communication link and control system interaction
between the diesel particulate filter and the engine necessitated
in thermally regenerated systems; and 13) Heat release from
particulate oxidation is utilized for generating additional heat
for aftertreatment light off and subsequent emissions reduction
effectiveness.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The drawings illustrate the best known mode of carrying out
the present invention, including several embodiments of a
particulate trap regeneration system incorporating the above
advantages and in which:
[0024] FIG. 1 is a diagrammatic illustration prior art system for
operating a lean burn diesel engine utilizing a passive and active
thermal Diesel Particulate Filter (DPF) regeneration along with a
Selective Catalytic Reduction (SCR) or Lean NOx Trap (LNT) for
reducing the engine's NOx emissions;
[0025] FIG. 2 is a diagrammatic illustration of a first embodiment
of a passive or passive/electrically active particulate matter
oxidation system according to the teachings of the present
invention;
[0026] FIG. 3 is a diagrammatic illustration of an external
particulate matter oxidation system that traps particulate matter
in a filter and oxidizes the particulate matter by flowing exhaust
manifold gases out of the exhaust manifold and into a settling
tank;
[0027] FIG. 4 is a diagrammatic illustration of a second embodiment
of an external particulate matter oxidation system similar to the
system illustrated in FIG. 3, and further including a valve for
controlling flow out of the exhaust manifold into the settling
tank;
[0028] FIG. 5 is a diagrammatic illustration of an additional
embodiment similar to the systems illustrated in FIGS. 3 and 4, and
further including the oxidation system attached to the engine's
exhaust pipe;
[0029] FIG. 6 is a diagrammatic illustration of a system similar to
the embodiment illustrated in FIG. 3, and further including a
second filter for trapping ash;
[0030] FIG. 7 is a diagrammatic illustration of a system similar to
the systems illustrated in FIGS. 3 and 6, and further including a
valve to facilitate oxidization of the particulate matter in the
first and second filter for trapping particulate matter and ash;
and
[0031] FIG. 8 is a diagrammatic illustration of another system
similar to the system illustrated in FIG. 4, wherein the system is
constructed to function with vacuum, pressure, or any combination
of the two regeneration methods.
DETAILED DESCRIPTION
[0032] FIG. 1 illustrates a prior art system for oxidizing
particulate matter produced by a combustion engine. In the system
illustrated in FIG. 1, a Selective Catalytic Reduction (SCR) or
Lean NOx Trap (LNT) (either of which is referenced as numeral 32)
is placed downstream of a diesel particulate filter (DPF) 28 for
reducing the Nitrous Oxide (NOx) and Particulate Matter (PM) from a
diesel engine 20 having an exhaust manifold 23 associated
therewith.
[0033] In this known system, particulate matter is oxidized in the
substrate (not illustrated) of DPF 28. Advanced, known injection
timing produces NOx emissions with considerable NO, and after
coming in contact with the expensive rare earth elements in Diesel
Oxidation Catalyst (DOC) 24, is converted into NO2. Engine 20, DOC
24, PF 28, and SCR or LNT 32 are in fluid communication via an
exhaust pipe 22 which exits from engine 20 and carries with it
exhaust therefrom. A turbo 80 to provide a boost in output may also
be included in the system illustrated in FIG. 1.
[0034] Because NO2 is less stable than NO and the temperature is
above .about.250.degree. Celsius, the NO2 will react with any
stored soot in DPF 28, thus oxidizing particulate matter into CO2.
If the operating temperature is below .about.250.degree. Celsius,
the particulate matter remains stored in DPF 28 and must be cleaned
by many different thermal methods which could include, for example,
late injection of fuel into the cylinder of engine 20 to increase
the exhaust temperature above the .about.250.degree. Celsius
oxidation point condition for NO2 and over 500.degree. Celsius for
02 oxidation. The time required for a complete regeneration may not
ever be available, thus initiating warning lights and intervention
by the operator.
[0035] As shown and illustrated in FIG. 1, urea 40 may be injected
into exhaust emissions of the combustion engine via a urea injector
42 included in prior art systems upstream and/or downstream from
DPF 28. FIG. 1 illustrates a urea injector 42 in locations both
upstream and downstream from DPF 28.
[0036] FIG. 1 further illustrates various other known components
long associated with engines such as engine 20 including: intake
throttle valve 50 used during shutdown to keep engine 20 from
shaking and throttling (e.g., reducing) air flow to the engine,
exhaust gas recirculation (EGR) cooler 54 for reducing the Nitrogen
Oxide (NOx) which causes acid rain and smog, clean up oxidation
catalyst 60 which used if urea or Diesel Exhaust Fluid (DEF) is not
used in reductant chemical reactions and allowed to exit the
tailpipe, and an Exhaust Gas Recirculation (EGR) Valve as commonly
known and understood in the art.
[0037] FIG. 2 is a diagrammatic illustration of a system for
oxidizing particulate matter according to the teachings of the
present invention. In a first embodiment, the system uses a porous
volume, or particulate matter oxidation system (PMOS) 69 located
within exhaust manifold 23. The volume can be either be a solid
porous volume or have a porous outer shell. Non-thermal
regeneration pressures from engine 20 may overcome valve 75, which
could be a simple check valve to enter PMOS 69 within exhaust
manifold 23. When this takes place, particulate matter exhaust
gases and other components of exhaust enter the volume within
exhaust manifold 23.
[0038] Exhaust manifold 23 preferably includes pressurized gases
pulsating into the volume during blow down of the cylinders of
engine 20, wherein the gases may be provided in a plurality of
manners known in the art. In addition to the blow down of
combustion gases, transient engine operation creates pressure in
exhaust manifold 23, and increases and decreases the differential
pressure and subsequent flow in and out of the porous volume. The
flow of high temperature exhaust manifold gas preferably passively
oxidizes the particulate matter within PMOS 69.
[0039] In some embodiments, the walls of PMOS 69 or its whole
volume may be coated with an oxidation catalyst such as platinum to
reduce the passive regeneration time. Other foreseeable catalysts
known in the art besides platinum such as vanadium may also be used
in certain embodiments. When vanadium is used, the catalyst is
sulfur tolerant, and Platinum preferably generates NO.sub.2 from
the NO available in the exhaust manifold gases.
[0040] Gases may subsequently reenter the exhaust stream before
traveling through an SCR/DPF 30. Flow from exhaust pipe 22 to
SCR/DPF 30 may be regulated by a valve 34, while flow from SCR/DPF
30 to an output may be regulated by a valve 36. Passing the
manifold gases through the SCR/DPF 30 allows the NOx to be
converted along with the rest of the exhaust stream.
[0041] Settling tank 39 including a valve associate therewith is
preferably in fluid connection with exhaust pipe 22. Settling tank
39 is of the type known or foreseeable in the art for separating
impurities from the various gases of the system.
[0042] In at least one alternative embodiment, urea could be
directly injected into PMOS 69 or exhaust manifold 23. Such an
embodiment allows for early urea injection, thus providing for low
temperature operations and reducing corrosiveness of downstream
components such as turbo 80.
[0043] FIG. 3 illustrates another embodiment in which exhaust
manifold 23 and settling tank 39 are connected via PMOS 69. In the
embodiment illustrated in FIG. 3, PMOS 69 traps particulate matter
in a filter 70 and oxidizes the particulate matter by flowing
exhaust manifold gases out of exhaust manifold 23 and into settling
tank 39. Exhaust manifold gases are preferably released via exhaust
manifold 23. This may be an important process during passive
regeneration when the amount NOx entering and coming into contact
with oxidation catalyst coated wire mesh or equivalent filter 70
will need to be varied.
[0044] A heating element such as heating element 78 may be used to
help provide thermal energy to the particulate in order to convert
the particulate matter from a solid and liquid phase to that of gas
capable of passing through the particulate filter and SCR/DPF 30.
It should be noted that the SCR/DPF 30 substrate could be a simple
particulate filter catalyzed with an oxidation catalyst, selective
catalytic reduction catalyst, or a simple uncatalyzed bare filter.
Other foreseeable alternative substitutes are also contemplated
herein.
[0045] FIG. 4 is a diagrammatic illustration of a second embodiment
of an external particulate matter oxidation system similar to the
system illustrated in FIG. 3, and further including a valve 79 that
can either be a two position on/off valve or proportional for
controlling flow out of exhaust manifold 23 into settling tank 39.
Closing control valve 79 during peak accelerating conditions
preferably increases or maximizes the exhaust and intake pressures
(boost pressure), and subsequently the power output of engine
20.
[0046] FIG. 4 also includes an electronically controlled engine
fitted with an Electronic Control Module (ECM) 90. ECM 90 may
control valve 79 and variable geometry turbo 80 to further assist
in controlling the flow of exhaust manifold gases into PMOS 69
while sensing and controlling the correct amount of exhaust flow
through PMOS 69 to match the supplemental heating element 78
capabilities. During low load conditions where passive regeneration
would not occur, thermal energy generated by heat element 78
assists in the direct oxidation of the particulate matter. In this
manner, oxidation of the particulate matter can be achieved even
with the engine at idle conditions.
[0047] Exhaust manifold gases may leave exhaust manifold 23 when
valve 79 is open. When valve 79 is shut, the volume is pressurized
by exhaust manifold 23. Flow similar to that of FIG. 2 provides
pressurized exhaust gases flow in and out during transient
operation. This transient flow allows passive regeneration even
when flow to the settling tank 39 is unavailable due to engine
performance requirements.
[0048] FIG. 5 is a diagrammatic illustration of an additional
embodiment similar to FIGS. 3 and 4, but wherein PMOS 69 is
attached to EGR piping 52 instead of attaching to exhaust manifold
23 of the oxidation system. Such a configuration allows the
flexibility of the system to be retrofitted to older, legacy
vehicles because the exhaust manifold would not have to be removed
to fit the system to the vehicle. Also, servicing the piping is
preferably improved.
[0049] FIG. 6 illustrates a system similar to FIGS. 3, 4, and 5.
However, instead of the gases flowing through entire distance to
the SCR/DPF combination 30 via the settling tank 39 and through
valve 38, gases can be redirected into the exhaust stream near
turbo 80. A first, high porosity filter 74 provided between heating
element 78 and exhaust pipe 22 designed to trap and assist in
oxidizing the particulate matter either with or without an
oxidation catalyst and subsequent NO2 generation.
[0050] A second filter 76 for trapping ash and preventing it from
reentering the main engine filter is placed downstream from filter
74 and is preferably a lower pore size filter with mean pore size
levels smaller than or close to SCR/DPF combination 30. After
oxidizing the particulate in filter 74, ash may pass through filter
74 before being captured in filter 76. The volume between filters
74, 76 is preferably large enough to hold the expected ash that can
be accumulated for the life of the aftertreatment system.
Alternatively, there could be any manner of volume between filters
74, 76 to create a volume and prevent filter 76 from plugging with
ash. Filter 76 being in the vertical position with the ash volume
directly below and out of the flow path is just one non-limiting
example of a solution. While the system illustrates utilizes two
filters for holding, oxidizing, and storing ash, in some
embodiments, only one such filter is used.
[0051] FIG. 7 is a diagrammatic illustration of a system similar to
the systems illustrated in FIGS. 3 and 6 but further including
valve 79 to allow the pressurization of the particulate
regeneration system utilizing a first high porosity filter 74 to
oxidize the particulate matter in PMOS 69 and second filter 76 for
trapping the ash from returning to the main engine filter. Valve 79
can replace or be used in addition to valve 72, the latter of which
is illustrated in FIG. 7. Valve 79 operates substantially similarly
to valve 79 in FIGS. 4 and 5 in that the closing of valve 79 would
allow pressurization of the Particulate Matter Regeneration System
(PRMS). In addition to the pressurization, back a forth flow from
engine transient operation is preferably achieved.
[0052] FIG. 8 is a diagrammatic illustration of another embodiment
of the present system similar to FIG. 4, but instead of pressurized
non-thermal active regeneration system, the system can function
with vacuum, pressure, or any combination of the two regeneration
methods.
[0053] From the foregoing, it will be seen that the various
embodiments of the present invention are well adapted to attain all
the objectives and advantages hereinabove set forth together with
still other advantages which are obvious and which are inherent to
the present structures. It will be understood that certain features
and sub-combinations of the present embodiments are of utility and
may be employed without reference to other features and
sub-combinations. Since many possible embodiments of the present
invention may be made without departing from the spirit and scope
of the present invention, it is also to be understood that all
disclosures herein set forth or illustrated in the accompanying
drawings are to be interpreted as illustrative only and not
limiting. The various constructions described above and illustrated
in the drawings are presented by way of example only and are not
intended to limit the concepts, principles and scope of the present
invention.
[0054] Thus, there has been shown and described several embodiments
of a novel system for oxidizing particulate matter using exhaust
manifold gases. As is evident from the foregoing description,
certain aspects of the present invention are not limited by the
particular details of the examples illustrated herein, and it is
therefore contemplated that other modifications and applications,
or equivalents thereof, will occur to those skilled in the art. The
terms "having" and "including" and similar terms as used in the
foregoing specification are used in the sense of "optional" or "may
include" and not as "required".
[0055] Many changes, modifications, variations and other uses and
applications of the present constructions will, however, become
apparent to those skilled in the art after considering the
specification and the accompanying drawings. All such changes,
modifications, variations and other uses and applications which do
not depart from the spirit and scope of the invention are deemed to
be covered by the invention which is limited only by the claims
which follow.
* * * * *
References