U.S. patent application number 15/346225 was filed with the patent office on 2018-05-10 for reductant spray and exhaust gas flow guide and deflector.
This patent application is currently assigned to GM GLOBAL TECHNOLOGY OPERATIONS LLC. The applicant listed for this patent is GM GLOBAL TECHNOLOGY OPERATIONS LLC. Invention is credited to Andrea Arnone, Joshua Clifford Bedford, Claudio Ciaravino.
Application Number | 20180128146 15/346225 |
Document ID | / |
Family ID | 62003296 |
Filed Date | 2018-05-10 |
United States Patent
Application |
20180128146 |
Kind Code |
A1 |
Ciaravino; Claudio ; et
al. |
May 10, 2018 |
REDUCTANT SPRAY AND EXHAUST GAS FLOW GUIDE AND DEFLECTOR
Abstract
An after-treatment (AT) system for an exhaust gas flow from an
internal combustion engine includes first and second AT devices
positioned in the exhaust gas flow. The AT system also includes an
exhaust passage for carrying the flow of exhaust gas from the first
AT device to the second AT device. The AT system additionally
includes an injector configured to generate a reductant spray into
the exhaust passage and a sensor positioned proximate the injector
for detecting a concentration of a pollutant in the exhaust gas
flow downstream of the first AT device. The AT system furthermore
includes a deflector arranged between the injector and the sensor
and configured to guide the flow of exhaust gas to the sensor to
thereby concentrate the flow of exhaust gas at the sensor and
direct the reductant spray away from the sensor to thereby minimize
detection of the reductant by the sensor.
Inventors: |
Ciaravino; Claudio; (Torino,
IT) ; Bedford; Joshua Clifford; (Farmington Hills,
MI) ; Arnone; Andrea; (Turin, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GM GLOBAL TECHNOLOGY OPERATIONS LLC |
Detroit |
MI |
US |
|
|
Assignee: |
GM GLOBAL TECHNOLOGY OPERATIONS
LLC
Detroit
MI
|
Family ID: |
62003296 |
Appl. No.: |
15/346225 |
Filed: |
November 8, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01N 3/021 20130101;
F01N 2610/02 20130101; F01N 3/103 20130101; F01N 13/0093 20140601;
Y02A 50/20 20180101; Y02T 10/12 20130101; F01N 2610/1453 20130101;
F01N 3/2066 20130101; Y02A 50/2325 20180101; F01N 3/2892 20130101;
F01N 3/0842 20130101; F01N 11/007 20130101; F01N 2560/02 20130101;
Y02T 10/24 20130101; F01N 13/008 20130101; F01N 2240/20
20130101 |
International
Class: |
F01N 3/20 20060101
F01N003/20; F01N 13/00 20060101 F01N013/00; F01N 11/00 20060101
F01N011/00; F01N 3/10 20060101 F01N003/10; F01N 3/021 20060101
F01N003/021; F01N 3/08 20060101 F01N003/08 |
Claims
1. An after-treatment (AT) system for a flow of exhaust gas from an
internal combustion engine, the AT system comprising: a first AT
device; a second AT device positioned in the flow of exhaust gas
downstream of the first AT device; an exhaust passage configured to
carry the flow of exhaust gas from the first AT device to the
second AT device; an injector configured to generate a spray of a
reductant into the exhaust passage; a sensor positioned proximate
the injector and configured to detect a concentration of a
pollutant in the flow of exhaust gas downstream of the first AT
device; and a deflector arranged between the injector and the
sensor and configured to guide the flow of exhaust gas to the
sensor to thereby concentrate the flow of exhaust gas at the sensor
and direct the spray of the reductant away from the sensor to
thereby minimize detection of the reductant by the sensor.
2. The AT system of claim 1, wherein the first AT device is encased
within a first housing, the second AT device is encased within a
second housing, the exhaust passage is configured as a transfer
pipe between the first and second housings, and wherein the first
housing, the second housing, and the transfer pipe are joined in a
unitary assembly.
3. The AT system of claim 2, wherein each of the deflector, the
injector, and the sensor is arranged in the transfer pipe.
4. The AT system of claim 3, wherein the deflector is positioned in
the transfer pipe to permit the injector to generate an
unrestricted reductant spray cone having at least a 24 degree
angle.
5. The AT system of claim 3, wherein the deflector is fixed to a
structure of the transfer pipe.
6. The AT system of claim 5, wherein the transfer pipe is a cast
component and the deflector is cast into the transfer pipe.
7. The AT system of claim 1, wherein the deflector is characterized
by a curved shape having a concave surface facing the injector and
a convex surface facing the sensor.
8. The AT system of claim 7, wherein the curved shape of the
deflector is characterized by a length equal to or greater than a
distance the sensor protrudes into the flow of exhaust gas within
the transfer pipe.
9. The AT system of claim 1, wherein: the internal combustion
engine is a compression-ignition engine; the reductant is a
diesel-exhaust-fluid (DEF) having an aqueous solution of urea; and
the pollutant is nitrogen oxide (NO.sub.X).
10. The AT system of claim 9, wherein: the first AT device is one
of a diesel oxidation catalyst (DOC) and a lean NO.sub.X trap
(LNT); and the second AT device is a dual-function substrate
including a selective catalytic reduction (SCR) catalyst and a
diesel particulate filter (DPF).
11. A vehicle comprising: an internal combustion engine configured
to generate a flow of exhaust gas as a byproduct of generating
power; and an exhaust system connected to the engine and having an
after-treatment (AT) system for the flow of exhaust gas, the AT
system including: a first AT device; a second AT device positioned
in the flow of exhaust gas downstream of the first AT device; an
exhaust passage configured to carry the flow of exhaust gas from
the first AT device to the second AT device; and an injector
configured to generate a spray of a reductant into the exhaust
passage; a sensor positioned proximate the injector and configured
to detect a concentration of a pollutant in the flow of exhaust gas
downstream of the first AT device; and a deflector arranged between
the injector and the sensor and configured to guide the flow of
exhaust gas to the sensor to thereby concentrate the flow of
exhaust gas at the sensor and direct the spray of the reductant
away from the sensor to thereby minimize detection of the reductant
by the sensor.
12. The vehicle of claim 11, wherein the first AT device is encased
within a first housing, the second AT device is encased within a
second housing, the exhaust passage is configured as a transfer
pipe between the first and second housings, and wherein the first
housing, the second housing, and the transfer pipe are joined in a
unitary assembly.
13. The vehicle of claim 12, wherein each of the deflector, the
injector, and the sensor is arranged in the transfer pipe.
14. The vehicle of claim 13, wherein the deflector is positioned in
the transfer pipe to permit the injector to generate an
unrestricted reductant spray cone having at least a 24 degree
angle.
15. The vehicle of claim 13, wherein the deflector is fixed to a
structure of the transfer pipe.
16. The vehicle of claim 15, wherein the transfer pipe is a cast
component and the deflector is cast into the transfer pipe.
17. The vehicle of claim 11, wherein the deflector is characterized
by a curved shape having a concave surface facing the injector and
a convex surface facing the sensor.
18. The vehicle of claim 17, wherein the curved shape of the
deflector is characterized by a length equal to or greater than a
distance the sensor protrudes into the flow of exhaust gas within
the transfer pipe.
19. The vehicle of claim 11, wherein: the internal combustion
engine is a compression-ignition engine; the reductant is a
diesel-exhaust-fluid (DEF) having an aqueous solution of urea; and
the pollutant is nitrogen oxide (NO.sub.X).
20. The vehicle of claim 19, wherein: the first AT device is one of
a diesel oxidation catalyst (DOC) and a lean NO.sub.X trap (LNT);
and the second AT device is a dual-function substrate including a
selective catalytic reduction (SCR) catalyst and a diesel
particulate filter (DPF).
Description
INTRODUCTION
[0001] The present disclosure is drawn to a guide and deflector for
a reductant spray and an exhaust gas flow in an exhaust gas
after-treatment (AT) system employed by an internal combustion
engine.
[0002] Various exhaust after-treatment (AT) devices, such as
particulate filters and other devices, have been developed to
effectively limit exhaust emissions from internal combustion
engines. One of the exhaust after-treatment devices frequently used
in a modern lean burn internal combustion engine, such as a
compression-ignition or diesel type, is a selective catalytic
reduction (SCR) catalyst.
[0003] The SCR is configured to convert nitrogen oxides (NO.sub.X)
into diatomic nitrogen (N.sub.2) and water (H.sub.2O) with the aid
of the NO.sub.2 generated by another exhaust after-treatment
device, typically the diesel oxidation catalyst (DOC). For
effective removal of NO.sub.X, the SCR conversion process
additionally requires a predetermined amount of ammonia (NH.sub.3)
to be present in the exhaust gas flow.
[0004] The SCR conversion process may additionally require a
controlled or metered amount of a reductant having a general name
of "diesel-exhaust-fluid" (DEF) into the exhaust gas flow, when the
reductant is employed in diesel engines. Such a reductant may be an
aqueous solution of urea that includes water and ammonia.
SUMMARY
[0005] An after-treatment (AT) system for a flow of exhaust gas of
an internal combustion engine includes a first AT device and a
second AT device in fluid communication with and positioned in the
flow of exhaust gas downstream of the first AT device. The AT
system also includes an exhaust passage configured to carry the
flow of exhaust gas from the first AT device to the second AT
device. The AT system additionally includes an injector configured
to generate a spray of a reductant into the exhaust passage and a
sensor positioned proximate the injector and configured to detect a
concentration of a pollutant in the flow of exhaust gas downstream
of the first AT device. The AT system furthermore includes a
deflector arranged between the injector and the sensor and
configured to guide the flow of exhaust gas to the sensor to
thereby concentrate the flow of exhaust gas at the sensor and
direct the spray of the reductant away from the sensor to thereby
minimize detection of the reductant by the sensor.
[0006] The first AT device may be encased within a first housing,
the second AT device may be encased within a second housing, and
the exhaust passage may be configured as a transfer pipe between
the first and second housings. Furthermore, the first housing, the
second housing, and the transfer pipe may all be joined in a
unitary assembly.
[0007] Each of the deflector, the injector, and the sensor may be
arranged in the transfer pipe.
[0008] The deflector may be positioned in the transfer pipe to
permit the injector to generate an unrestricted reductant spray
cone having at least a 24 degree angle.
[0009] The deflector may be fixed to a structure of the transfer
pipe.
[0010] The transfer pipe may be a cast component and the deflector
may be cast into the transfer pipe.
[0011] The deflector may be characterized by a curved shape having
a concave surface facing the injector and a convex surface facing
the sensor.
[0012] The curved shape of the deflector may be characterized by a
length equal to or greater than, i.e., at least coextensive with, a
distance the sensor protrudes into the flow of exhaust gas within
the transfer pipe.
[0013] As disclosed, the internal combustion engine may be a
compression-ignition engine, the reductant may be a
diesel-exhaust-fluid (DEF) having an aqueous solution of urea, and
the pollutant may be nitrogen oxide (NO.sub.X).
[0014] The first AT device may be either a diesel oxidation
catalyst (DOC) or a lean NO.sub.X trap (LNT). The second AT device
may be a dual-function substrate including a selective catalytic
reduction (SCR) catalyst and a diesel particulate filter (DPF).
[0015] A vehicle employing the above-described AT system is also
disclosed.
[0016] The above features and advantages, and other features and
advantages of the present disclosure, will be readily apparent from
the following detailed description of the embodiment(s) and best
mode(s) for carrying out the described disclosure when taken in
connection with the accompanying drawings and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a schematic plan view of a vehicle having an
internal combustion engine connected to an exhaust system having an
after-treatment (AT) system with a number of AT devices for
reducing exhaust emissions.
[0018] FIG. 2 is a schematic illustration of the internal
combustion engine connected to the exhaust system with the
after-treatment (AT) system shown in FIG. 1.
[0019] FIG. 3 is a schematic perspective partial cut-away view of
the AT system shown in FIG. 1, illustrating a reductant injector, a
pollutant concentration sensor, and an embodiment of a deflector
for guiding a flow of exhaust gas to the sensor and directing a
spray of the reductant away from the sensor.
[0020] FIG. 4 is a schematic perspective partial cut-away view of
the AT system shown in FIG. 1, illustrating another embodiment of
the deflector.
DETAILED DESCRIPTION
[0021] Referring to the drawings, wherein like reference numbers
refer to like components throughout the several views, FIG. 1
schematically depicts a motor vehicle 10. The vehicle 10 includes
an internal combustion engine 12 configured to propel the vehicle
via driven wheels 14. Although the internal combustion engine 12
may be a spark-ignition type, specific reference throughout the
ensuing disclosure will be made to a compression-ignition or diesel
type of an engine. As understood by those skilled in the art,
internal combustion in the diesel engine 12 occurs when a specific
amount of ambient air flow 16 is mixed with a metered amount of
fuel 18 supplied from a fuel tank 20 and the resultant air-fuel
mixture is compressed inside the engine's cylinders (not
shown).
[0022] As shown, the engine 12 includes an exhaust manifold 22 and
a turbocharger 24. The turbocharger 24 is energized by a flow of
exhaust gas, specifically the exhaust gas flow 26 released by
individual cylinders of the engine 12 through the exhaust manifold
22 following each combustion event. The turbocharger 24 is
connected to an exhaust system 28 that receives exhaust gas flow 26
and eventually releases the gas flow to the ambient, typically on a
side or aft of the vehicle 10. Although the engine 12 is depicted
as having the exhaust manifold 22 attached to the engine structure,
the engine may include exhaust passages (not shown) such as
generally formed in exhaust manifolds. In such a case, the above
passages may be incorporated into the engine structure, such as the
engine's cylinder head(s). Furthermore, although the turbocharger
24 is shown, nothing precludes the engine 12 from being configured
and operated without such a power augmentation device.
[0023] The vehicle 10 also includes an engine exhaust
after-treatment (AT) system 30. The AT system 30 includes a number
of exhaust after-treatment devices configured to methodically
remove largely carbonaceous particulate byproducts and emission
constituents of engine combustion from the exhaust gas flow 26. As
shown in FIGS. 1 and 2, the AT system 30 operates as part of the
exhaust system 28. The AT system 30 includes a first AT device 32
close-coupled to the turbocharger 24 and a second AT device 34
positioned in the exhaust gas flow 26 downstream and close-coupled
to the first AT device. As employed herein, the term
"close-coupled" with respect to the arrangement of the first and
second AT devices 32, 34 denotes each of the subject devices being
in close proximity to each other and arranged inside an engine
compartment 11 of the vehicle 10 for close proximity to the engine
12.
[0024] The close-coupled arrangement of the first and second AT
devices 32, 34 reduces length of the exhaust passage (to be
described in detail below) for carrying the exhaust gas flow 26
from the first AT device 32 to the second AT device 34.
Consequently, such close-coupling of the first and second AT
devices 32, 34 to the engine 12 provides a compact packaging
arrangement that minimizes time for activation, i.e., light-off, of
the AT system 30 in after-treatment of the exhaust gas flow 26
following a cold-start of the engine 12. As shown, the first AT
device 32 may be a diesel oxidation catalyst (DOC) or a lean
nitrogen oxide (NO.sub.X) trap (LNT), while the second AT device 34
may be a dual-function substrate including a selective catalytic
reduction (SCR) catalyst or an SCR on filter (SCRF) and a diesel
particulate filter (DPF).
[0025] The primary function of the DOC is reduction of carbon
monoxides (CO) and non-methane hydrocarbons (NMHC). When present,
the DOC is additionally configured to generate nitrogen dioxide
(NO.sub.2), which may be used by the SCR arranged remotely
downstream of the DOC and described in greater detail below. The
DOC typically contains a catalyst substance made up of precious
metals, such as platinum and/or palladium, which function therein
to accomplish the above-noted objectives. Generally, with respect
to generation of NO.sub.2, the DOC becomes activated and reaches
operating efficiency at elevated temperatures. Therefore, as shown
in FIGS. 1 and 2, the DOC may be close-coupled to the turbocharger
24 in order to reduce loss of thermal energy from the exhaust gas
flow 26 prior to the gas reaching the DOC.
[0026] The primary function of the LNT is to reduce oxides of
nitrogen or NO.sub.X that are emitted by the engine 12 in the
exhaust gas flow 26 as a byproduct of the reaction of nitrogen and
oxygen gases in the air following a combustion event. The LNT
removes NO.sub.X molecules from the exhaust gas flow 26 by
adsorption, i.e., trapping and storing them internally during
operation of the engine 12, thus acting like a molecular sponge.
Typically, the LNT includes a ceramic substrate structure with a
catalyzed wash-coat, i.e., mixed with an active precious metal,
that is applied to channels of the substrate.
[0027] The primary function of the SCR is to convert nitrogen
oxides (NO.sub.X) into diatomic nitrogen (N.sub.2) and water
(H.sub.2O), for example, with the aid of the NO.sub.2 generated by
the first AT device 32 configured as the DOC. The SCR may be
configured as a 1-way filter, which filters particulate matter or
soot, or a 2-way filter, which includes a catalyzed wash-coat, and
carries two functions--filters particulate matter and reduces
NO.sub.X. For effective removal of NO.sub.X, the SCR conversion
process additionally requires a predetermined amount of ammonia
(NH.sub.3) to be present in the fuel-rich exhaust gas flow 26.
[0028] The primary function of the DPF is to collect and dispose of
particulate matter emitted by the engine 12. The DPF acts as a trap
for removing the particulate matter, specifically, soot, from the
exhaust flow 26. Similar to the DOC described above, the DPF may
contain precious metals, such as platinum and/or palladium, which
would function as a catalyst to accomplish the noted objective.
When used with an SCRF, however, such precious metals in the DPF
could be removed.
[0029] As shown, the DOC or the LNT first AT device 32 is
positioned upstream of the second AT device 34 including the SCR
and DPF. The AT system 30 also includes an exhaust passage 36
configured to carry the flow of exhaust gas 26 from the first AT
device 32 to the second AT device 34. The exhaust passage 36 may be
part of a transfer pipe 38 fluidly connecting the first and second
AT devices 32, 34. As part of the AT system 30, an injector 40 is
arranged downstream of the first AT device 32. The injector 40 is
configured to generate a spray of a reductant 42 containing ammonia
(NH.sub.3), such as an aqueous solution of urea, a.k.a.,
diesel-exhaust-fluid (DEF), into the exhaust passage 36. As shown
in FIG. 1, the injector 40 may receive the reductant 42 from a
refillable reservoir 44. Also part of the AT system 30, a sensor 46
is positioned proximate the injector 40. The sensor 46 is
configured to detect a concentration of a pollutant, such as
NO.sub.X, and also of oxygen (O.sub.2) in the flow of exhaust gas
26 downstream of the first AT device 32.
[0030] The AT system 30 also includes a controller 48. The
controller 48 may be a stand-alone unit, or be part of an
electronic control unit (ECU) that regulates the operation of
engine 12. The controller 48 is arranged on the vehicle 10 and
includes a processor and a readily accessible non-transitory
memory. Instructions for controlling operation of the AT system 30
are programmed or recorded in the memory of the controller 48 and
the processor is configured to execute the instructions from the
memory during operation of the vehicle 10. The controller 48 is
generally programmed to regulate the injector 40 for introducing
the reductant 42 into the exhaust passage 36 during operation of
the engine 12. The controller 48 is also in communication with the
sensor 46 for regulating the injector 40 in response to the
detected concentration of the particular pollutant, as well as for
regulation of other engine systems.
[0031] As shown in FIG. 3, a deflector 50 is arranged in the
exhaust passage 36 between the injector 40 and the sensor 46. The
deflector 50 is configured to guide the flow of exhaust gas 26 to
the sensor 46, to thereby concentrate the flow of exhaust gas at
the sensor. A stratified flow of the exhaust gas flow 26 may thus
cause a misreading by the sensor 46. Accordingly, such
concentration of the flow of exhaust gas 26 at the sensor 46 is
intended to improve a sampling quality of the exhaust gas flowing
through the exhaust passage 36, i.e., ensure quality sensor reading
of NO.sub.X in the flow of the exhaust gas 26. The deflector 50 is
also configured to direct or deflect the spray of the reductant 42
away from the sensor 46, to thereby minimize detection of the
reductant by the sensor.
[0032] The sensor 46 configured to detect NO.sub.X may be
cross-sensitive to ammonia, accordingly, a presence of ammonia at
or around the sensor may be misread as a higher concentration of
NO.sub.X. A swirling flow of the exhaust gas flow 26 containing
ammonia may thus cause a misreading by the sensor 46. Such a
misreading of NO.sub.X may result in improper closed-loop control
of the engine 10 by the controller 48 using the detected NO.sub.X
concentration data. Furthermore, such a misreading of NO.sub.X
concentration may result in the controller 48 erroneously reporting
that the AT system 30 is insufficiently effective in removing
NO.sub.X from the exhaust gas flow 26.
[0033] With resumed reference to FIG. 2, the first AT device 32 may
be encased within a first housing 52, while the second AT device 34
may be encased within a second housing 54. The transfer pipe 38 is
arranged between and connects the first and second housings 52, 54.
As shown, the first housing 52, the second housing 54, and the
transfer pipe 38 may be joined in a unitary assembly 56. In such a
construction of the AT system 30, each of the injector 40, the
sensor 46, and the deflector 50, may be arranged in the transfer
pipe 38. The deflector 50 may be specifically positioned in the
transfer pipe 38 to permit the injector 40 to generate an
unrestricted reductant spray cone 42A having at least a 24 degree
angle .theta..
[0034] As shown in FIG. 3, the deflector 50 may be fixed to a
structure of the transfer pipe 38. Specifically, the transfer pipe
38 may be a cast component, for example from iron or steel, welded
to the first and second housings 52, 54. In such an embodiment, the
deflector 50 may also be a cast feature incorporated into, i.e.,
formed with, the transfer pipe 38. Other manufacturing methods for
generating the desired shape of the transfer pipe 38 along with the
deflector 50, for example via machining, may also be employed. As
shown in FIG. 4, the deflector 50 may be characterized by a curved
shape having a concave surface 48A facing the injector 40 and a
convex surface 50B facing the sensor 46. The curved shape of the
deflector 50 may be additionally characterized by a length L that
is equal to or greater than, i.e., at least coextensive with, a
distance D that the sensor 46 protrudes into the flow of exhaust
gas 26 within the transfer pipe 38.
[0035] Overall, the deflector 50 permits a compact, close-coupled
package of the first and second AT devices 32, 34 to the engine 12
without loss of a quality reading of concentration of the
particular pollutant in the exhaust gas flow 26 at the sensor 46.
As a result, such effective close-coupled packaging of the first
and second AT devices 32, 34 to the engine 12 facilitates effective
cold-start operation of the AT system 30, i.e., quicker light-off
of the respective AT devices.
[0036] The detailed description and the drawings or figures are
supportive and descriptive of the disclosure, but the scope of the
disclosure is defined solely by the claims. While some of the best
modes and other embodiments for carrying out the claimed disclosure
have been described in detail, various alternative designs and
embodiments exist for practicing the disclosure defined in the
appended claims. Furthermore, the embodiments shown in the drawings
or the characteristics of various embodiments mentioned in the
present description are not necessarily to be understood as
embodiments independent of each other. Rather, it is possible that
each of the characteristics described in one of the examples of an
embodiment may be combined with one or a plurality of other desired
characteristics from other embodiments, resulting in other
embodiments not described in words or by reference to the drawings.
Accordingly, such other embodiments fall within the framework of
the scope of the appended claims.
* * * * *