U.S. patent application number 11/548446 was filed with the patent office on 2008-04-17 for tailpipe exhaust gas mixer and method.
This patent application is currently assigned to INTERNATIONAL ENGINE INTELLECTUAL PROPERTY COMPANY , LLC. Invention is credited to Jason C. Lin, Shouhao Wu.
Application Number | 20080087006 11/548446 |
Document ID | / |
Family ID | 38924753 |
Filed Date | 2008-04-17 |
United States Patent
Application |
20080087006 |
Kind Code |
A1 |
Wu; Shouhao ; et
al. |
April 17, 2008 |
TAILPIPE EXHAUST GAS MIXER AND METHOD
Abstract
An engine system (100) includes an internal combustion engine
(101) connected to an exhaust system (102). A portion (103) of the
exhaust system (102) is connected to the internal combustion engine
(101), and an additional portion (111) of the exhaust system (102)
is connected to a vehicle and includes a tailpipe (123). An
after-treatment system (105, 109) is connected to the engine (100)
located between the internal combustion engine (101) and the
tailpipe (111). A mixer (200) is located between a first segment of
the tailpipe (202) and a second segment of the tailpipe (204). The
mixer (200) is arranged to mix a flow of exhaust gas (214) from the
first segment of the tailpipe (202) with a flow or air (218) to
yield a mixture, and to route the mixture into the second segment
of the tailpipe (204).
Inventors: |
Wu; Shouhao; (Roselle,
IL) ; Lin; Jason C.; (Naperville, IL) |
Correspondence
Address: |
INTERNATIONAL ENGINE INTELLECTUAL PROPERTY COMPANY
4201 WINFIELD ROAD, P.O. BOX 1488
WARRENVILLE
IL
60555
US
|
Assignee: |
INTERNATIONAL ENGINE INTELLECTUAL
PROPERTY COMPANY , LLC
Warrenville
IL
|
Family ID: |
38924753 |
Appl. No.: |
11/548446 |
Filed: |
October 11, 2006 |
Current U.S.
Class: |
60/280 |
Current CPC
Class: |
F01N 2470/30 20130101;
F01N 3/106 20130101; Y02A 50/20 20180101; Y02T 10/40 20130101; F01N
3/035 20130101; F01N 2250/10 20130101; Y02A 50/2322 20180101; Y02T
10/47 20130101; F01N 13/009 20140601; F01N 13/082 20130101; F01N
11/002 20130101; F01N 3/023 20130101; F01N 2270/02 20130101; F01N
3/05 20130101 |
Class at
Publication: |
60/280 |
International
Class: |
F01N 5/00 20060101
F01N005/00 |
Claims
1. An engine system, comprising: an internal combustion engine
connected to an exhaust system, wherein a portion of the exhaust
system is connected to the internal combustion engine, and an
additional portion of the exhaust system is connected to a vehicle
and includes a tailpipe; an after-treatment system connected to the
vehicle, wherein the after-treatment system is connected to the
exhaust system and disposed between the internal combustion engine
and the tailpipe; a mixer that is disposed between a first segment
of the tailpipe and a second segment of the tailpipe, wherein the
mixer is arranged to mix a flow of exhaust gas from the first
segment of the tailpipe with a flow or air to yield a mixture, and
wherein the mixer is arranged to route the mixture into the second
segment of the tailpipe.
2. The engine system of claim 1, wherein the mixer is disposed
inline with the first segment and the second segment.
3. The engine system of claim 1, wherein the mixer comprises: an
upstream portion connected to the first segment; a downstream
portion connected to the second segment; a neck-down portion that
forms a nozzle opening, the neck-down portion disposed between the
first segment and the second segment; a plurality of tabs disposed
around the neck-down portion and arranged to connect the first
segment and the second segment; wherein a gap is defined between
the first segment, the second segment, and the plurality of tabs,
and wherein the gap is arranged and constructed to pass the flow of
air therethrough.
4. The engine system of claim 3, wherein the first segment has a
first inner diameter, wherein the nozzle opening has a second inner
diameter, and wherein the second inner diameter is smaller than the
first inner diameter.
5. The engine system of claim 3, wherein the plurality of tabs is
three tabs, and wherein the three tabs are arranged symmetrically
around the nozzle opening.
6. The engine system of claim 3, wherein a low pressure region is
created on the downstream portion side of the nozzle opening during
operation.
7. The engine system of claim 1, wherein the mixer comprises: an
upstream portion connected to the first segment; a downstream
portion connected to the second segment; a neck-down portion
connected to the upstream portion; a neck-up portion connected to
the downstream portion; a mixing region disposed between the
neck-down portion and the neck-up portion; wherein the mixing
region defines a nozzle opening, and wherein a plurality of
openings fluidly connects the mixing region with an ambient supply
of air.
8. The engine system of claim 7, further comprising a shield
disposed around the mixing region, wherein a cavity is defined
between the mixing region and the shield, and wherein an air path
is defined for the flow of air from the ambient supply of air,
through a gap disposed between the shield and at least one of the
first segment and the second segment, through the cavity, and
through the plurality of openings.
9. A method of reducing a temperature of an exhaust gas stream in a
tailpipe of a vehicle, comprising the steps of: generating a flow
of exhaust gas during operation of an engine; treating the flow of
exhaust gas with at least one after-treatment component; routing
the flow of exhaust gas to a tailpipe that includes a mixer;
admitting the flow of exhaust gas into the mixer; mixing the flow
of exhaust gas with a flow of air in the mixer to yield a mixture;
and expelling the mixture from the mixer.
10. The method of claim 9, further comprising the step of filtering
a particulate matter from the flow of exhaust gas in a particulate
filter.
11. The method of claim 10, further comprising the step of
increasing a temperature of the flow of exhaust gas when the
particulate filter is in a regeneration stage of operation.
12. The method of claim 11, further comprising the step of cooling
the flow of exhaust gas that is accomplished by the step of mixing
the flow of exhaust gas with the flow of air.
13. The method of claim 9, further comprising the step of passing
the flow of air through a gap defined between a first segment of
the tailpipe and a second segment of the tailpipe.
14. The method of claim 9, wherein the mixer is a venturi mixer,
and wherein the step of mixing further includes the steps of:
accelerating the flow of exhaust gas; creating a low pressure
region adjacent to a nozzle opening; and supplying the flow of air
into the low pressure region.
15. The method of claim 9, further comprising the step of admitting
the flow of air through a plurality of openings.
16. A method of diluting exhaust gas generated by an internal
combustion engine installed in a vehicle, comprising the steps of:
generating a flow of exhaust gas from the internal combustion
engine; admitting the flow of exhaust gas into a particulate
filter; increasing a temperature of the flow of exhaust gas passing
through the particulate filter at times when the particulate filter
is regenerating; admitting the flow of exhaust gas at an elevated
temperature into a mixer; admitting a flow of air into the mixer;
mixing the flow of exhaust gas at the elevated temperature with the
flow of air to yield a mixture; expelling the mixture from the
mixer.
17. The method of claim 16, further comprising the step of passing
the flow of air through a gap.
18. The method of claim 16, wherein the mixer is a venturi mixer,
and wherein the step of mixing further includes the steps of:
accelerating the flow of exhaust gas; creating a low pressure
region adjacent to a nozzle opening; and supplying the flow of air
into the low pressure region.
19. The method of claim 16, further comprising the step of
admitting the flow of air into the mixer through a plurality of
openings.
Description
FIELD OF THE INVENTION
[0001] This invention relates to internal combustion engines,
including but not limited to exhaust passages containing
after-treatment devices for the internal combustion engine.
BACKGROUND OF THE INVENTION
[0002] Internal combustion engines generate exhaust gas during
operation that contains various chemical compounds. Many modern
engines include after-treatment devices associated therewith for
treating some of these chemical compounds in the exhaust gas.
Typical after-treatment components may include Oxidation Catalysts
(OC) and particulate filters (PF). Compression ignition engines in
particular, may use such devices for treating their exhaust
gas.
[0003] Treatment, or after-treatment as it is commonly known, is a
process of treating exhaust gas that is generated during the
operation of an engine and before it is released to the
environment. In a typical vehicle, for example, an engine might be
connected to an exhaust pipe, or tail pipe, that may carry exhaust
gases away from the engine. The vehicle tail pipe may include
various after-treatment components, along with other components,
for example, mufflers, valves, and so forth.
[0004] During operation of an engine, a temperature of the exhaust
gases that are generated depends on various factors. During normal
engine operation, the temperature of exhaust gas may depend
primarily on the speed and load of the engine, and also on other
factors, such as barometric pressure, ambient temperature, and so
forth. During an idle condition, the temperature of exhaust gas in
the tail pipe is expected to be relatively low, for example on some
engines about 400 deg. F. (200 deg. C.). During conditions of high
loading, for example when the vehicle is traveling at a higher rate
of speed under a high load, the temperature of exhaust gas might
reach temperatures of 1,500 deg. F. (815 deg. C.).
[0005] PF regeneration, as is known, is a periodic process by which
trapped matter in the PF burns off to clean the PF. The addition of
after-treatment devices, such as a PF, might increase the
temperature of exhaust gas at times when such temperature would
otherwise be low. This increase in temperature may be due to a
regeneration event of the PF that might be taking place, for
example, while the engine is idling.
[0006] Accordingly, there is a need for avoiding exhaust
temperature increases in vehicle tailpipes during times when such
temperatures are expected to be low.
SUMMARY OF THE INVENTION
[0007] Exhaust temperature increases in vehicle tailpipes during
times when such temperatures are expected to be low may
advantageously be avoided as described herein. An engine system
includes an internal combustion engine connected to an exhaust
system. A portion of the exhaust system is connected to the
internal combustion engine, and an additional portion of the
exhaust system is connected to a vehicle and includes a tailpipe.
An after-treatment system is connected to the engine located
between the internal combustion engine and the tailpipe. A mixer is
located between a first segment of the tailpipe and a second
segment of the tailpipe. The mixer is arranged to mix a flow of
exhaust gas from the first segment of the tailpipe with a flow or
air to yield a mixture, and to route the mixture into the second
segment of the tailpipe.
[0008] A method of reducing a temperature of an exhaust gas stream
in a tailpipe of a vehicle includes the step of generating a flow
of exhaust gas during operation of an engine. The flow of exhaust
gas may be treated with at least one after-treatment component, and
routed to a tailpipe that includes a mixer. The flow of exhaust gas
may be admitted into the mixer where it may be mixed with a flow of
air in the mixer to yield a mixture. The mixture, being
advantageously at a lower temperature than the flow of exhaust gas
may be expelled from the mixer.
[0009] A method of diluting exhaust gas that is generated by an
internal combustion engine installed in a vehicle, includes the
steps of admitting the flow of exhaust gas into a particulate
filter, and increasing a temperature of the flow of exhaust gas
passing through the particulate filter at times when the
particulate filter is regenerating. The flow of exhaust gas at an
elevated temperature is admitted into a mixer, along with a flow of
air that is also admitted into the mixer. The flow of exhaust gas
at the elevated temperature may be mixed with the flow of air to
yield a mixture at a lower temperature, which may be expelled from
the mixer into the environment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a block diagram of an engine system having a mixer
in a tailpipe in accordance with the invention.
[0011] FIG. 2 and FIG. 3 are cross sections of an exhaust gas mixer
in accordance with the invention.
[0012] FIG. 4 and FIG. 5 are cross sections of another embodiment
of an exhaust gas mixer in accordance with the invention.
[0013] FIG. 6 is a flowchart for a method of reducing a temperature
of an exhaust gas stream in a tailpipe of a vehicle in accordance
with the invention.
[0014] FIG. 7 is a flowchart for a method of diluting exhaust gas
that is generated by an internal combustion engine installed in a
vehicle in accordance with the invention.
DESCRIPTION OF A PREFERRED EMBODIMENT
[0015] The following describes an apparatus for and method of
diluting an exhaust gas stream in a vehicle tail pipe with ambient
air, in order to reduce a temperature of the exhaust stream before
releasing it to the environment.
[0016] A block diagram of an engine system 100 having an
after-treatment system 102 is shown in FIG. 1. The engine system
100 includes a base engine 101 that is connected to an exhaust pipe
103. During operation of the base engine 101 in a vehicle (not
shown), an exhaust gas stream 104 that is generated may be carried
away from the base engine 101 and to the after-treatment system 102
through the exhaust pipe 103. The exhaust gas stream 104 is denoted
by hollowed-head arrows.
[0017] The exhaust pipe 103 is connected to an oxidation catalyst
(OC) 105, which in turn is connected to a pipe segment 107 leading
to a particulate filter (PF) 109. The PF 109 is connected to a
tailpipe 111 which may also include a muffler (not shown) or other
components. The after-treatment system 102 may also include a
variety of sensors to monitor its operation. For example, a first
temperature sensor 113 may be disposed in the pipe segment 107
upstream of the PF 109, and a second temperature sensor 114 may be
disposed in the tailpipe 111 downstream of the PF 109. The
after-treatment system 102 may also include one or more pressure
sensor(s) 115 connected upstream and/or downstream of the PF 109 to
monitor it's operation and extent of loading with particulate
matter. Information from the sensors 113, 114, and 115 may be
relayed to an electronic control unit (ECU) 119. The
after-treatment system 102 may include additional components than
the ones described herein for illustration, for example, the system
102 may include a lean NOx trap (LNT), a urea-based selective
catalytic reduction (SCR) system, or a diesel fuel reformer system
(DFRS), and so forth.
[0018] At times when a regeneration of the PF 109 is initiated, a
temperature T1 of the exhaust gas stream 104 before the PF 109 may
substantially increase to a temperature T2 after the PF 109. On a
typical engine, the exhaust gas stream 104 would exit the tailpipe
111 at the temperature T2.
[0019] It is advantageous to the sociability of the vehicle to
avoid higher temperature exhaust gas emissions from the tailpipe
111. For this reason, a mixer device 120 may be connected in-line
with the tailpipe 111. The mixer 120 may advantageously be a
venturi mixer that mixes a flow of fresh air 121, denoted by the
solid headed arrows, that is pulled in from outside the tailpipe
111, with the exhaust gas stream 104, to yield a mixture 122 that
may pass through a downstream portion 123 of the tailpipe 111. One
portion of the mixture 122 is exhaust gas at the temperature T2,
and a remaining portion of the mixture 122 is fresh air at an
ambient temperature T3. A resultant temperature T4 of the mixture
122 may advantageously be lower than the temperature T2 of the
exhaust gas stream 104, which is advantageous to the sociability of
the vehicle.
[0020] One embodiment of an exhaust gas dilution mixer 200 is shown
in FIG. 2 and FIG. 3 in different cross section views. The mixer
200 may be connected in-line with a first tailpipe segment 202 and
a second tailpipe segment 204. The first tailpipe segment 202 may
have a first inner diameter "D" extending up to a neck-down portion
206. The neck-down portion 206 of the segment 202 may reduce the
diameter D to an inner diameter "d" at a nozzle opening 208. The
segment 204 may lie past the opening 208 and have the same inner
diameter D as the segment 202, or may alternatively have a larger
inner diameter "D'". A plurality of connector tabs 210 may connect
the first segment 202 with the second segment 204. A gap or opening
212 may be defined between the segments 202 and 204, and between
the tabs 210.
[0021] At times when a flow of exhaust gas 214, denoted by
hollow-head arrows, enters the mixer 200 through an upstream
portion 216 thereof, the exhaust gas flow 214 flows through the
segment 202 under a pressure and velocity that depends on the
diameter D. When the flow of exhaust gas 214 reaches the neck-down
portion 206, it is gradually accelerated to pass through the
opening 208. The higher velocity, and thus lower static pressure,
of the flow of exhaust gas 214 passing through the opening 208
depends on the smaller inner diameter d. A low static pressure and
high flow momentum of the accelerated flow of exhaust gas 214
exiting the opening 208 advantageously draws in a flow of ambient
air 218, denoted by solid-head arrows, through the opening 212. The
flow of exhaust gas 214 may mix and be diluted by the flow of
ambient air 218 to yield a mixture. The mixture of flows 214 and
218 may flow out of the mixer from a downstream portion 220
thereof, at a velocity and pressure that depends on the inner
diameter D'. The mixture in the downstream portion 220 is
advantageously at a lower temperature than the flow in the upstream
portion 216.
[0022] Another embodiment of an exhaust gas dilution mixer 400 is
shown in FIG. 4 and FIG. 5 in different cross section views. The
mixer 400 may be connected in-line with a first tailpipe segment
402 and a second tailpipe segment 404. The first tailpipe segment
402 may have a first inner diameter "D" extending up to a neck-down
portion 406. The neck-down portion 406 of the segment 402 may
reduce the diameter D to an inner diameter "d" at a nozzle opening
408. The segment 404 may lie past the opening 408 and have the same
inner diameter D as the segment 402, or may alternatively have a
larger inner diameter "D'". A neck-up portion 409 may smoothly
transition between the diameter d of the opening 408 to the
diameter D' of the segment 404. A plurality of openings 410 may
fluidly connect a region 411 that is adjacent to the opening 408
with the environment. Advantageously, the region 411 is connected
to the environment through a cavity 412 that is partially defined
between an outer surface of the region 411 and a shield 413. The
cavity 412 is in fluid communication with the region 411 through
the plurality of openings 410, and with the environment through a
gap 415 between the shield 413 and either one or both of the tube
segment(s) 402 and 404.
[0023] At times when a flow of exhaust gas 414, denoted by
hollow-head arrows, enters the mixer 400 through an upstream
portion 416 thereof, the exhaust gas flow 414 flows through the
segment 402 under a pressure and velocity that depends on the
diameter D. When the flow of exhaust gas 414 reaches the neck-down
portion 406, it is gradually accelerated to pass through the
opening 408. The higher velocity, and thus lower static pressure,
of the flow of exhaust gas 414 passing through the opening 408 at
the region 411 depends on the smaller inner diameter d. A low
static pressure and high flow momentum of the accelerated flow of
exhaust gas 414 passing through the region 411 advantageously draws
in a flow of ambient air 418, denoted by solid-head arrows, through
the plurality of openings 410. The flow of exhaust gas 414 may mix
and be diluted by the flow of ambient air 418 to yield a mixture.
The mixture of flows 414 and 418 may pass through the opening 408,
through the neck-up portion 409, and flow out of the mixer 400 from
a downstream portion 420 thereof, at a velocity and pressure that
depends on the inner diameter D'. The mixture in the downstream
portion 420 is advantageously at a lower temperature than the flow
in the upstream portion 416.
[0024] The openings 410 may advantageously be arranged
symmetrically around the region 411. The shield 413 is optional and
may be used to avoid intrusion of debris, and especially water,
into the mixer 400 through the openings 410. The shield 413 may be
connected to one or both of the segment(s) 402 and 404 of the
tailpipe with tabs (not shown) or any other suitable connection
arrangement. Embodiments other than the ones shown that use a
venturi effect for mixing an exhaust flow in a tailpipe with
ambient air may advantageously be used to dilute the flow of
exhaust gas and lower it's temperature in the tailpipe.
[0025] A flow chart for a method of reducing a temperature of an
exhaust gas stream in a tailpipe of a vehicle is shown in FIG. 6.
An engine associated with a vehicle may be connected to an exhaust
system, and may generate a flow of exhaust gas during operation at
step 602. The exhaust system may include various exhaust gas
treatment components, or after-treatment components, that are
arranged to treat a flow of exhaust gas passing therethrough at
step 604. The flow of exhaust gas, having passed through the
after-treatment components, may be routed into the tailpipe step
606. The tailpipe may be a part of the exhaust system of the
vehicle that releases exhaust gas to the environment.
[0026] The tailpipe may include an inline mixer device. The flow of
exhaust gas in the tailpipe may enter the mixer at step 608, be
accelerated at step 610, be mixed with a flow of air from the
environment to yield a mixture at step 612, and exit the mixer at
step 614. The mixture may advantageously be at a lower temperature
than the flow of exhaust gas. The flow of air from the environment
may pass through a gap between two adjacent segments of the
tailpipe, or may enter a region thereof through a plurality of
openings. The mixer may advantageously use a "venturi" effect to
augment mixing between the flow of exhaust gas and the flow of
air.
[0027] A flow chart for a method of diluting exhaust gas generated
by an internal combustion engine installed in a vehicle is shown in
FIG. 7. The internal combustion engine may generate a flow of
exhaust gas during operation at step 702. The flow of exhaust gas
may enter a particulate filter at step 704. At times when the
particulate filter is regenerating, a temperature of the flow of
exhaust gas may increase at step 706. The flow of exhaust gas, at
the elevated temperature, may enter a mixer at step 708. A flow of
air may also enter the mixer at step 710, where it may be mixed
with the flow of exhaust gas at step 712 to yield a mixture. The
mixture may exit the mixer at step 714.
[0028] The present invention may be embodied in other specific
forms without departing from its spirit or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrative and not restrictive. The scope of
the invention is, therefore, indicated by the appended claims
rather than by the foregoing description. All changes that come
within the meaning and range of equivalency of the claims are to be
embraced within their scope.
* * * * *