U.S. patent application number 12/907342 was filed with the patent office on 2012-04-19 for multiple flow path exhaust treatment system.
Invention is credited to Timothy Gardner, Adam J. Kotrba, Jeremy Popovich, Argun Yetkin, Guanyu Zheng.
Application Number | 20120090304 12/907342 |
Document ID | / |
Family ID | 45932883 |
Filed Date | 2012-04-19 |
United States Patent
Application |
20120090304 |
Kind Code |
A1 |
Kotrba; Adam J. ; et
al. |
April 19, 2012 |
Multiple Flow Path Exhaust Treatment System
Abstract
A vehicle exhaust system for an engine having a plurality of
combustion chambers includes a first emission treatment device, a
second emission treatment device and a housing defining a first
exhaust passageway in fluid communication with the combustion
chambers and containing the first emission treatment device. A
second parallel exhaust passageway is in fluid communication with
the combustion chambers and contains the second emission treatment
device. The first and second passageways share a common wall having
a serpentine shape such that the cross-sectional area of the
passageways varies along a direction of exhaust flow. The first
emission treatment device is positioned at a location of increased
cross-sectional area in the first passageway and the second
emission treatment device is positioned at an axially offset
location of increased cross-sectional area in the second
passageway.
Inventors: |
Kotrba; Adam J.;
(Laingsburg, MI) ; Popovich; Jeremy; (Brooklyn,
MI) ; Zheng; Guanyu; (Farmington, MI) ;
Gardner; Timothy; (Canton, MI) ; Yetkin; Argun;
(Ann Arbor, MI) |
Family ID: |
45932883 |
Appl. No.: |
12/907342 |
Filed: |
October 19, 2010 |
Current U.S.
Class: |
60/301 |
Current CPC
Class: |
F01N 3/0211 20130101;
F01N 13/009 20140601; Y02T 10/12 20130101; F01N 2590/10 20130101;
Y02A 50/2325 20180101; Y02T 10/20 20130101; F01N 2590/02 20130101;
F01N 2590/08 20130101; F01N 3/103 20130101; Y02A 50/20 20180101;
F01N 3/2066 20130101; F01N 2410/00 20130101; F01N 13/011
20140603 |
Class at
Publication: |
60/301 |
International
Class: |
F01N 3/10 20060101
F01N003/10 |
Claims
1. A vehicle exhaust system for an engine having a plurality of
combustion chambers, comprising: a first emission treatment device;
a second emission treatment device; and a housing including a first
exhaust passageway in fluid communication with the combustion
chambers and containing the first emission treatment device, the
housing further including a second parallel exhaust passageway in
fluid communication with the combustion chambers and containing the
second emission treatment device, the first and second passageways
sharing a common wall having a serpentine shape such that the
cross-sectional area of the first and second exhaust passageways
varies along a direction of exhaust flow, the first emission
treatment device being positioned at a location of increased
cross-sectional area in the first passageway and the second
emission treatment device being positioned at an axially offset
location of increased cross-sectional area in the second
passageway.
2. The exhaust system of claim 1 wherein a sum of the
cross-sectional area of the first emission treatment device and the
cross-sectional area of the second emission treatment device is
greater than a cross-sectional area of the housing at the first
emission treatment device position.
3. The exhaust system of claim 1 wherein the cross-sectional area
of the first and second emission treatment devices is substantially
the same.
4. The exhaust system of claim 1 wherein the first and second
emission treatment devices include diesel particulate filters.
5. The exhaust system of claim 1 further including a third emission
treatment device positioned within the first passageway downstream
of the first emission treatment device.
6. The exhaust system of claim 5 further including a fourth
emission treatment device positioned within the second passageway
downstream of the second emission treatment device.
7. The exhaust system of claim 6 wherein the cross-sectional area
of the first and third emission treatment devices is substantially
the same.
8. The exhaust system of claim 7 wherein the third and fourth
emission treatment devices include selective catalytic reduction
elements.
9. A vehicle exhaust system for an engine having a plurality of
combustion chambers, comprising: a housing; a first array of
parallel positioned emission treatment devices; a second array of
parallel positioned emission treatment devices, the first and
second arrays being axially spaced apart within the housing; a
first exhaust passageway in fluid communication with the combustion
chambers and containing the first array of emission treatment
devices; and a second and separate exhaust passageway in fluid
communication with the combustion chambers and containing the
second array of emission treatment devices, the first and second
passageways extending parallel to one another within the housing,
wherein the first exhaust passageway includes a portion bypassing
the second array of emission treatment devices and wherein the
second passageway includes a portion bypassing the first array of
emission treatment devices.
10. The exhaust system of claim 9 wherein the bypassing portion of
the first passageway extends parallel to the second array.
11. The exhaust system of claim 10 wherein the bypassing portion of
the second passageway extends parallel to the first array.
12. The exhaust system of claim 11 wherein an upstream end of the
bypassing portion of the first passageway is positioned downstream
of the first array.
13. The exhaust system of claim 12 wherein a downstream end of the
bypassing portion of the second passageway is positioned upstream
of the second array.
14. The exhaust system of claim 9 further including a third array
of parallel positioned emission treatment devices axially spaced
apart from the first and second arrays, and a third separate
exhaust passageway in fluid communication with the combustion
chambers and containing the third array of emission treatment
devices, wherein the third passageway extends parallel to the first
and second passageways and includes a portion bypassing the first
and second arrays.
15. The exhaust system of claim 14 wherein the bypassing portion of
the third passageway extends parallel to the first and second
arrays.
16. The exhaust system of claim 14 wherein ends of each of the
first, second and third passageways are in communication with each
other at an outlet of the housing.
17. The exhaust system of claim 16 wherein ends of each of the
first, second and third passageways are in communication with each
other at a collector portion of the housing in receipt of exhaust
from the combustion chambers.
18. The exhaust system of claim 14 wherein each of the bypassing
portions of the first, second and third passageways is positioned
adjacent to two emission treatment devices.
Description
FIELD
[0001] The present disclosure generally relates to a system for
treating exhaust gases. More particularly, an exhaust system having
multiple parallel flow paths is discussed.
BACKGROUND
[0002] To reduce the quantity of NO.sub.X and particulate matter
emitted to the atmosphere during internal combustion engine
operation, a number of exhaust aftertreatment devices have been
developed. A need for exhaust aftertreatment systems particularly
arises when diesel combustion processes are implemented. Typical
aftertreatment systems for diesel engine exhaust may include one or
more of a diesel particulate filter (DPF), a selective catalytic
reduction (SCR) system, a hydrocarbon (HC) injector, and a diesel
oxidation catalyst (DOC).
[0003] During engine operation, the DPF traps soot emitted by the
engine and reduces the emission of particulate matter (PM). Over
time, the DPF becomes loaded and begins to clog. Periodically,
regeneration or oxidation of the trapped soot in the DPF is
required for proper operation. To regenerate the DPF, relatively
high exhaust temperatures in combination with an ample amount of
oxygen in the exhaust stream are needed to oxidize the soot trapped
in the filter.
[0004] The DOC is typically used to generate heat useful for
regenerating the soot loaded DPF. When hydrocarbons (HC) are
sprayed over the DOC at or above a specific light-off temperature,
the HC will oxidize. This reaction is highly exothermic and the
exhaust gases are heated during light-off. The heated exhaust gases
are used to regenerate the DPF.
[0005] Known exhaust treatment devices have successfully operated
in conjunction with relatively small displacement internal
combustion engines for automotive use. However, other applications
including diesel locomotives, stationary power plants, marine
vessels and others may be equipped with relatively large diesel
compression engines having many large combustion chambers. The
exhaust mass flow rate from the larger engines may be more than ten
times the maximum flow rate typically provided to the exhaust
treatment device. While it may be possible to increase the size of
the exhaust treatment device to account for the increased exhaust
mass flow rate, the cost, weight and packaging concerns associated
with this solution may be unacceptable. Therefore, a need may exist
in the art for an exhaust arrangement to reduce undesirable
emissions from the exhaust output from a large diesel engine while
minimally affecting the cost, weight, size and performance of the
exhaust system.
SUMMARY
[0006] This section provides a general summary of the disclosure,
and is not a comprehensive disclosure of its full scope or all of
its features.
[0007] A vehicle exhaust system for an engine having a plurality of
combustion chambers includes a first emission treatment device, a
second emission treatment device and a housing defining a first
exhaust passageway in fluid communication with the combustion
chambers and containing the first emission treatment device. A
second parallel exhaust passageway is in fluid communication with
the combustion chambers and contains the second emission treatment
device. The first and second passageways share a common wall having
a serpentine shape such that the cross-sectional area of the
passageways varies along a direction of exhaust flow. The first
emission treatment device is positioned at a location of increased
cross-sectional area in the first passageway and the second
emission treatment device is positioned at an axially offset
location of increased cross-sectional area in the second
passageway.
[0008] A vehicle exhaust system for an engine having a plurality of
combustion chambers includes a housing, a first array of parallel
positioned emission treatment devices and a second array of
parallel positioned emission treatment devices. The first and
second arrays are axially spaced apart from one another and
positioned within the housing. A first exhaust passageway is in
fluid communication with the combustion chambers and contains the
first array of emission treatment devices. A second and separate
exhaust passageway is in fluid communication with the combustion
chambers and contains the second array of emission treatment
devices. The first and second passageways extend parallel to one
another within the housing. The first exhaust passageway includes a
portion bypassing the second array of emission treatment devices
and the second passageway includes a portion bypassing the first
array of emission treatment devices.
[0009] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples
in this summary are intended for purposes of illustration only and
are not intended to limit the scope of the present disclosure.
DRAWINGS
[0010] The drawings described herein are for illustrative purposes
only of selected embodiments and not all possible implementations,
and are not intended to limit the scope of the present
disclosure.
[0011] FIG. 1 is a schematic depicting an exhaust system having
multiple flow paths; and
[0012] FIG. 2 is a schematic depicting another exhaust system
having multiple flow paths.
[0013] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings.
DETAILED DESCRIPTION
[0014] Example embodiments will now be described more fully with
reference to the accompanying drawings.
[0015] Referring initially to FIG. 1, an exhaust system 10 for an
engine 12 is shown. The exhaust system 10 and engine 12 are mounted
to a vehicle. The engine 12 generates torque to move the vehicle.
As will be described in greater detail below, the exhaust system 10
receives exhaust from the engine 12 and treats the exhaust before
it flows to the outside atmosphere (represented as "ATM" in FIG.
1).
[0016] The engine 12 includes a plurality of combustion chambers
14a, 14b, 14c. In the embodiment shown, engine 12 includes a first
combustion chamber 14a, a second combustion chamber 14b, and a
third combustion chamber 14c. However, it will be appreciated that
engine 12 could include any number of combustion chambers without
departing from the scope of the present disclosure.
[0017] In one embodiment, engine 12 is a diesel engine; however, it
will be appreciated that engine 12 could be of any suitable type
without departing from the scope of the present disclosure. During
operation, a fuel/air mixture is introduced into combustion
chambers 14a, 14b, 14c, and the fuel/air mixture combusts, which
drives a piston (not shown) to drive an output shaft. Rotation of
the output shaft ultimately drives one or more wheels (not shown)
to move the vehicle. Exhaust gas, soot, particulate and other
materials (collectively referred to as "exhaust"), are products of
the combustion within combustion chambers 14a, 14b, 14c. The
exhaust flows through the exhaust system 10, which treats the
exhaust before it flows to the outside atmosphere.
[0018] As shown in FIG. 1, the exhaust system 10 includes a
plurality of exhaust treatment devices (ETD) 16a, 16b, 18a and 18b.
It will be appreciated that the ETDs could include any suitable
device operable for decreasing undesirable matter in the exhaust
before the exhaust flows to the outside atmosphere. For instance,
in FIG. 1, ETDs 16a and 16b include a diesel particulate filter
(hereinafter "DPF"). ETDs 18a and 18b include selective catalytic
reduction devices (hereinafter "SCR" device). DPFs 16a, 16b collect
soot as the exhaust flows therethrough. SCRs 18a, 18b each include
a catalyst operable to reduce other undesirable emissions. Other
ETDs may include a diesel oxidation catalyst (hereinafter "DOC"), a
reductant injector, a burner or the like.
[0019] Exhaust system 10 includes a first passageway 19 and a
second passageway 20 extending parallel to one another. First
passageway 19 includes an inlet 21 in communication with each of
combustion chambers 14a, 14b, 14c. DPF 16a and SCR 18a are
positioned in series within first passageway 19. Exhaust travelling
through first passageway 19 passes through DPF 16a, SCR 18a and
exits exhaust system 10 at an outlet 22.
[0020] In similar fashion, second passageway 20 includes an inlet
24 in communication with each of combustion chambers 14a, 14b, 14c.
DPF 16b and SCR 18b are positioned in series within second
passageway 20. Exhaust travelling through second passageway 20
passes through DPF 16b, SCR 18b and escapes to atmosphere via an
outlet 26.
[0021] It should be appreciated that exhaust provided from
combustion chambers 14a, 14b and 14c is provided to both inlet 21
and inlet 24. The exhaust travels along the parallel paths at
substantially the same flow rate. A substantially similar flow rate
is achieved by matching the cross-sectional areas of DPF 16a and
DPF 16b as well as matching the cross-sectional areas of SCR 18a
and SCR 18b. Furthermore, not only does exhaust system 10 provide
parallel passageways 19 and 20 having a substantially equivalent
flow, but the maximum flow through each passageway is optimized by
maximizing the cross-sectional area of each ETD while maintaining a
relatively small cross-section for the overall exhaust system 10.
These goals are achieved by defining a common wall 30 between first
passageway 19 and second passageway 20 with a serpentine shape.
Wall 30 includes a first end 32 positioned mid-way between a first
outer wall 34 and a second outer wall 36. First passageway 19 is
defined by first outer wall 34 and common wall 30. Second
passageway 20 is defined by second outer wall 36 and common wall
30. Based on the position of first end 32, inlet 21 has a
cross-sectional area substantially the same as inlet 24.
[0022] The serpentine shape of common wall 30 allows DPF 16a and
DPF 16b to be positioned in an axially offset or staggered
arrangement. By positioning the DPFs in this manner, the sum of the
cross-sectional area of DPF 16a and the cross-sectional area of DPF
16b is greater than the cross-sectional area of exhaust system 10
as defined by first outer wall 34 and second outer wall 36 at the
axial location of either DPF. Common wall 30 may extend toward
first outer wall 34 and protrude into first passageway 19 to define
a minimal cross-sectional area at a first zone 40. The smallest
feasible cross-sectional area at first zone 40 may be determined by
calculating or measuring the resistance to flow provided by DPF 16a
or SCR 18a and assuring that the reduced area of first zone 40 does
not restrict flow greater than any of the ETDs within first
passageway 19. DPF 16b is axially positioned in an enlarged portion
of second passageway 20 in line with zone 40.
[0023] At another point in the flow path, common wall 30 protrudes
toward second outer wall 36 to define a minimum cross-sectional
area at a second zone 42 of second passageway 20. The
cross-sectional area of zones 40 and 42 are substantially the same.
DPF 16a is positioned in an enlarged portion of first passageway 19
across from zone 42. SCR 18a and SCR 18b are also offset and
staggered relative to one another such that the sum of the
cross-sectional area of SCR 18a and the cross-sectional area of SCR
18b is greater than the cross-sectional area of exhaust system 10
at any one axial position.
[0024] FIG. 2 provides a schematic representation of another
exhaust system identified at reference numeral 100. Exhaust system
100 includes a first housing 102 positioned in fluid communication
with a second housing 104. Housing 102 includes an inlet 106 in
communication with one or more combustion cylinders of an engine.
Second housing 104 includes an outlet 108 in communication with the
atmosphere. First housing 102 contains a plurality of diesel
oxidation catalysts identified at reference numerals 110a-110i.
Each DOC is coupled to a corresponding diesel particulate filter
112a-112i. Exhaust flows through housing 102 in a top-down
direction as viewed in FIG. 2. As such, each of DOC 110a-110i is
positioned in parallel and includes an upstream end in
communication with exhaust provided from the internal combustion
engine. Exhaust entering each of the DOCs 110a-110i flows through
the corresponding DPF 112a-112i. Each of DPFs 112a-112i includes an
outlet or downstream end positioned in parallel with the other
diesel particulate filter outlets. A collector 118 is in receipt of
the exhaust that passes through each of DPFs 112a-112i.
[0025] An inlet 120 of second housing is in communication with
collector 118. A plurality of SCRs 126a-126i are positioned within
second housing 104. More particularly, SCR 126a, 126b and 126c
define a first SCR array 128. SCRs 126d, 126e and 126f form a
second SCR array identified at reference numeral 130. SCRs 126g,
126h and 126i form a third SCR array 132. First array 128, second
array 130 and third array 132 are axially spaced apart from one
another within second housing 104. As will be described, the SCR
arrays are interconnected in parallel such that exhaust from
collector 118 flows through three parallel passageways prior to
rejoining at an end portion 136 of second housing 104. Furthermore,
the three SCRs within each SCR array are positioned in parallel
with one another.
[0026] As supplied from collector 118, exhaust enters inlet 120 of
second housing 104. A plate 140 is positioned within second housing
104 to direct exhaust from inlet 120 to one of three passageways. A
first passageway 142 includes an aperture 143 extending through
plate 140 to allow exhaust to travel through plate 140 into
communication with upstream ends of SCRs 126a, 126b and 126c. Once
this portion of the exhaust passes through the parallel SCRs of
first array 128, the exhaust travels through a bypass portion or
first tube 144 of first passageway 142. More particularly, an
upstream end of first tube 144 and downstream ends of SCRs 126a,
126b, 126c are in communication with each other. The downstream of
first tube 144 is in communication with end portion 136 and outlet
108.
[0027] A second passageway 150 provides exhaust gas from collector
118 to second array 130 via a bypass portion or second tube 152.
Another bypass portion identified as a third tube 154 includes an
upstream end in communication with the downstream ends of SCRs
128d, 128e and 128f. A downstream end of third tube 154 transfers
this portion of the exhaust flow to outlet 108.
[0028] A third passageway 160 provides a path for exhaust
travelling from collector 118 through third SCR array 132 and
exiting at outlet 108. Third passageway 160 includes a bypass
portion or fourth tube 162 having an inlet or upstream end passing
through plate 140 and a downstream end positioned in fluid
communication with upstream ends of SCRs 126g, 126h and 126i. The
downstream ends of the SCRs within third SCR array 132 are in
communication with outlet 108. Exhaust flowing through fourth tube
162 does not pass through any of the SCRs of first array 128 or
second array 130. Similarly, exhaust flowing through first
passageway 142 passes through only the SCRS of first SCR array 128
and bypasses the SCRs of second array 130 and third array 132. The
parallel path of second passageway 150 provides exhaust only to the
SCRs of second SCR array 130. It should be appreciated that through
the use of exhaust treatment device arrays, compartmentalization
and parallel pathways, a relatively high flow exhaust system
including multiple exhaust treatment devices may be provided in a
minimal volume.
[0029] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not
intended to be exhaustive or to limit the disclosure. Individual
elements or features of a particular embodiment are generally not
limited to that particular embodiment, but, where applicable, are
interchangeable and can be used in a selected embodiment, even if
not specifically shown or described. The same may also be varied in
many ways. Such variations are not to be regarded as a departure
from the disclosure, and all such modifications are intended to be
included within the scope of the disclosure.
* * * * *