U.S. patent application number 12/776475 was filed with the patent office on 2011-11-10 for compact reduction agent doser for use in an scr system of an internal combustion engine.
Invention is credited to Richard E. Winsor.
Application Number | 20110271662 12/776475 |
Document ID | / |
Family ID | 44303703 |
Filed Date | 2011-11-10 |
United States Patent
Application |
20110271662 |
Kind Code |
A1 |
Winsor; Richard E. |
November 10, 2011 |
COMPACT REDUCTION AGENT DOSER FOR USE IN AN SCR SYSTEM OF AN
INTERNAL COMBUSTION ENGINE
Abstract
An SCR system for use with an IC engine includes a reduction
agent doser and a catalytic reactor. The reduction agent doser
includes a tubular housing with an inside diameter. A target plate
is positioned crosswise in the housing and terminates at a distance
from the inside diameter of the housing. The target plate directs a
flow of exhaust gas in a radially outward direction. A baffle is
positioned crosswise in the housing downstream from the target
plate. The baffle terminates at the inside diameter of the housing
and includes a center opening for directing a flow of exhaust gas
in a radially inward direction. A diffuser plate is located
downstream from the baffle. The diffuser plate terminates at the
inside diameter of the housing. A catalytic reactor is directly
coupled with a downstream side of the reduction agent doser.
Inventors: |
Winsor; Richard E.;
(Waterloo, IA) |
Family ID: |
44303703 |
Appl. No.: |
12/776475 |
Filed: |
May 10, 2010 |
Current U.S.
Class: |
60/295 |
Current CPC
Class: |
B01F 5/0693 20130101;
F01N 3/2066 20130101; F01N 3/2892 20130101; B01F 3/04049 20130101;
B01F 2015/062 20130101; F01N 2610/1453 20130101; F01N 2610/102
20130101; Y02T 10/12 20130101; Y02T 10/24 20130101; B01F 15/066
20130101; B01F 5/0268 20130101; B01F 5/064 20130101 |
Class at
Publication: |
60/295 |
International
Class: |
F01N 3/10 20060101
F01N003/10 |
Claims
1. An internal combustion (IC) engine, comprising: an engine block
including a plurality of combustion cylinders; an exhaust system
for receiving exhaust gases from said combustion cylinders, said
exhaust system including an exhaust manifold and an exhaust conduit
for conducting exhaust gas from the engine; and an emissions
control system, including: a reduction agent doser having a tubular
housing with an inside diameter, a target plate positioned
crosswise in said housing and terminating at a distance from said
inside diameter of said housing, said target plate directing a flow
of the exhaust gas in a radially outward direction, a baffle
positioned crosswise in said housing downstream from said target
plate, said baffle terminating at said inside diameter of said
housing and including a center opening for directing a flow of the
exhaust gas in a radially inward direction, and a diffuser plate
located downstream from said baffle, said diffuser plate
terminating at said inside diameter of said housing; and a
catalytic reactor coupled with a downstream side of said reduction
agent doser.
2. The IC engine of claim 1, wherein said catalytic reactor has a
flow path diameter which is approximately the same as said inside
diameter of said housing.
3. The IC engine of claim 1, wherein said target plate is a
circular disk-shaped plate, and said baffle is annular shaped with
a circular center opening.
4. The IC engine of claim 1, wherein said catalytic reactor is
directly coupled to a downstream side of said reduction agent
doser.
5. The IC engine of claim 1, wherein said target plate is a heated
target plate.
6. The IC engine of claim 1, wherein said diffuser plate is a
perforated plate.
7. The IC engine of claim 1, wherein said emissions control system
includes a reduction agent injector for injecting a fluid reduction
agent toward said target plate.
8. The IC engine of claim 1, wherein said reduction agent doser is
a urea doser.
9. A reduction agent doser for use in an emissions control system
for an internal combustion (IC) engine, said reduction agent doser
comprising: a tubular housing with an inside diameter; a target
plate positioned crosswise in said housing and terminating at a
distance from said inside diameter of said housing, said target
plate directing a flow of exhaust gas in a radially outward
direction; a baffle positioned crosswise in said housing downstream
from said target plate, said baffle terminating at said inside
diameter of said housing and including a center opening for
directing a flow of exhaust gas in a radially inward direction; and
a diffuser plate located downstream from said baffle, said diffuser
plate terminating at said inside diameter of said housing.
10. The reduction agent doser of claim 9, wherein said target plate
is a circular disk-shaped plate, and said baffle is annular shaped
with a circular center opening.
11. The reduction agent doser of claim 9, wherein said target plate
is a heated target plate.
12. The reduction agent doser of claim 9, wherein said diffuser
plate is a perforated plate.
13. The reduction agent doser of claim 9, including a reduction
agent injector for injecting a fluid reduction agent toward said
target plate.
14. The reduction agent doser of claim 9, wherein said reduction
agent doser is a urea doser.
15. A selective catalytic reduction (SCR) system for use with an
internal combustion (IC) engine, comprising: a reduction agent
doser including: a tubular housing with an inside diameter; a
target plate positioned crosswise in said housing and terminating
at a distance from said inside diameter of said housing, said
target plate directing a flow of exhaust gas in a radially outward
direction; a baffle positioned crosswise in said housing downstream
from said target plate, said baffle terminating at said inside
diameter of said housing and including a center opening for
directing a flow of exhaust gas in a radially inward direction; and
a diffuser plate located downstream from said baffle, said diffuser
plate terminating at said inside diameter of said housing; and a
catalytic reactor directly coupled with a downstream side of said
reduction agent doser.
16. The reduction agent doser of claim 15, wherein said target
plate is a circular disk-shaped plate, and said baffle is annular
shaped with a circular center opening.
17. The reduction agent doser of claim 15, wherein said target
plate is a heated target plate.
18. The reduction agent doser of claim 15, wherein said diffuser
plate is a perforated plate.
19. The reduction agent doser of claim 15, wherein said reduction
agent doser includes a reduction agent injector for injecting a
fluid reduction agent toward said target plate.
20. The reduction agent doser of claim 15, wherein said reduction
agent doser is a urea doser.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to internal combustion
engines, and, more specifically, to exhaust aftertreatment of such
engines.
BACKGROUND OF THE INVENTION
[0002] A vehicle such as a work machine in the form of a
construction work machine, an agricultural work machine or a
forestry work machine, typically includes a power unit in the form
of an internal combustion (IC) engine. The IC engine may either be
in the form of a compression ignition engine (i.e., diesel engine)
or a spark ignition engine (i.e., gasoline engine). For most heavy
work machines, the power unit is in the form of a diesel engine
having better lugging, pull-down and torque characteristics for
associated work operations.
[0003] The Environmental Protection Laws enacted in the United
States decades ago have imposed ever increasing limits on permitted
emissions from IC engines. The diesel engine has enjoyed a position
of being a durable and fuel efficient engine thus making it the
engine of choice for commercial, industrial and agricultural use.
As emissions limits have been lowered, it becomes increasingly more
difficult to meet the standards with a diesel engine.
[0004] Diesel engines provide advantages in fuel economy, but
produce and emit both NOx and particulates during normal operation.
When primary measures (actions that affect the combustion process
itself, such as exhaust gas recirculation and engine timing
adjustments) are taken to reduce one, often the other is increased.
Thus, combustion conditions selected to reduce pollution from
particulates and obtain good fuel economy tend to increase the
output of NOx. Current and proposed regulations and legislation
present significant challenges to manufacturers to achieve good
fuel economy while at the same time reducing the emission levels of
particulates and NOx.
[0005] In order to meet such requirements or restrictions, a method
known as selective catalytic reduction (SCR) has been used for
reducing the emission of NOx. The SCR method consists of injecting
gaseous ammonia (NH3), ammonia in aqueous solution or aqueous urea,
or ammonia supplied from an ammonia generator using a solid source
of ammonia such as ammonia carbamate or ammonia carbonate, into the
exhaust gas system of the compression ignition engine as a
reduction agent. When the temperature of the exhaust gas stream is
above a reaction temperature, for example a temperature above
160.degree. C. for aqueous urea, the reduction agent undergoes a
hydrolysis process and is decomposed into ammonia and CO.sub.2. As
the exhaust gas stream is passed through the SCR catalyst, the
gaseous ammonia reacts with the NOx to reduce the NOx to molecular
nitrogen. This reduces or limits the NOx emissions from the
compression ignition engine.
[0006] In an SCR system as described above, the ammonia is
typically provided by evaporating and decomposing a urea-water
solution that is now referred to as a diesel emission fluid (DEF).
In a typical SCR system, the DEF is sprayed onto a mixer in an
exhaust pipe and a further length of exhaust pipe (typically 0.5 m
to 1.0 m) is provided after the mixer to complete the mixing before
entering the SCR catalytic reactor. An SCR system of this
conventional design requires considerable space and adds cost.
SUMMARY OF THE INVENTION
[0007] The invention in one form is directed to an IC engine
including an engine block with a plurality of combustion cylinders.
An exhaust system receives exhaust gases from the combustion
cylinders. The exhaust system includes an exhaust manifold and an
exhaust conduit for conducting the exhaust gas from the engine. An
emissions control system includes a reduction agent doser and a
catalytic reactor. The reduction agent doser has a tubular housing
with an inside diameter. A target plate is positioned crosswise in
the housing and terminates at a distance from the inside diameter
of the housing. The target plate directs a flow of the exhaust gas
in a radially outward direction. A baffle is positioned crosswise
in the housing downstream from the target plate. The baffle
terminates at the inside diameter of the housing and includes a
center opening for directing a flow of the exhaust gas in a
radially inward direction. A diffuser plate is located downstream
from the baffle, and terminates at the inside diameter of the
housing. A catalytic reactor is coupled with a downstream side of
the reduction agent doser.
[0008] The invention in another form is directed to a reduction
agent doser for use in an emissions control system for an IC
engine. The reduction agent doser includes:
[0009] a tubular housing with an inside diameter;
[0010] a target plate positioned crosswise in the housing and
terminating at a distance from the inside diameter of the housing,
the target plate directing a flow of exhaust gas in a radially
outward direction;
[0011] a baffle positioned crosswise in the housing downstream from
the target plate, the baffle terminating at the inside diameter of
the housing and including a center opening for directing a flow of
exhaust gas in a radially inward direction; and
[0012] a diffuser plate located downstream from the baffle, the
diffuser plate terminating at the inside diameter of the
housing.
[0013] The invention in yet another form is directed to an SCR
system for use with an IC engine, including a reduction agent doser
and a catalytic reactor. The reduction agent doser includes a
tubular housing with an inside diameter. A target plate is
positioned crosswise in the housing and terminates at a distance
from the inside diameter of the housing. The target plate directs a
flow of exhaust gas in a radially outward direction. A baffle is
positioned crosswise in the housing downstream from the target
plate. The baffle terminates at the inside diameter of the housing
and includes a center opening for directing a flow of exhaust gas
in a radially inward direction. A diffuser plate is located
downstream from the baffle. The diffuser plate terminates at the
inside diameter of the housing. A catalytic reactor is directly
coupled with a downstream side of the reduction agent doser.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic illustration of an embodiment of an
SCR system of the present invention for use with an IC engine;
and
[0015] FIG. 2 is a sectional view of the reduction agent doser
shown in FIG. 1, taken along line 2-2.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Referring now to the drawings, there is shown an embodiment
of an IC engine 10 which includes an SCR system 12 for reducing
exhaust emissions to the ambient environment. IC engine 10 is
presumed to be a diesel engine in the illustrated embodiment, and
includes an engine block 14 with a plurality of combustion
cylinders 16. Engine block 14 is shown with four combustion
cylinders 16, but may have any suitable number of combustion
cylinders depending upon the engine, such as two, six, or eight
cylinders. IC engine 10 also includes an intake manifold 18 and an
exhaust manifold 20 which are each in fluid communication with the
plurality of combustion cylinders 16. Intake manifold 18 receives
and provides a source of combustion air to the plurality of
combustion cylinders 16. Exhaust manifold 20 receives exhaust gases
from the plurality of combustion cylinders 16 and discharges the
exhaust gases through an exhaust conduit 22 to the downstream SCR
system 12.
[0017] SCR system 12 generally includes a reduction agent doser 24
and a catalytic reactor 26. Reduction agent doser 24 is assumed to
be a urea doser in the illustrated embodiment. Reduction agent
doser 24 includes a tubular housing 28 in which are disposed a
reduction agent injector 30, target plate 32, baffle 34, and
diffuser plate 36. The structure and arrangement of reduction agent
doser 24 is such that the various components thereof cause the
exhaust gases to flow in radially outward and radially inward
directions, thereby providing a sufficient latency period for
proper mixing of the DEF and exhaust gas within reduction agent
doser 24 prior to flowing into catalytic reactor 26. This reduces
the area required by reduction agent doser 24 while still
maintaining adequate mixing of the DEF with the exhaust gases.
[0018] Reduction agent injector 30 injects a fluid reduction agent,
such as DEF, toward target plate 32. The particular configuration
and impingement angle of reduction agent injector 30 may vary,
depending upon the application.
[0019] Target plate 32 generally provides an impingement surface
for the DEF which is mixed with the exhaust gases. Target plate 32
is positioned crosswise within housing 28 and terminates at a
distance from the inside diameter of housing 28. For example,
target plate 32 may be supported by a plurality of stand-off rods
38 which centrally locate the circular disk-shaped target plate 32
within the circular inside diameter of housing 28. The particular
diameter of target plate 32 may be selected according to desired
flow characteristics, flow rate, etc. Moreover, it is possible that
target plate 32 need not be a circular, disk-shaped plate but,
rather, have another shape for a particular application, such as
octagonal or hexagonal.
[0020] Baffle 34 is likewise positioned crosswise with housing 28
at a location which is downstream from target plate 32. Baffle 34
terminates at (i.e., extends to) the inside diameter of housing 28
and includes a center opening 40 for directing a flow of the
exhaust gas in a radially inward direction. In the embodiment
shown, baffle 34 has an annular shape and center opening 40 is a
concentrically positioned, circular opening with an inside diameter
which is smaller than the outside diameter of target plate 32.
Thus, as shown in FIG. 1, the exhaust gases first flow in a
radially outward direction around target plate 32 and then in a
radially inward direction to pass through center opening 40.
[0021] Diffuser plate 36 is located downstream from baffle 34 and
also terminates at the inside diameter of housing 28. Diffuser
plate 36 functions to distribute the exhaust gases mixed with DEF
in a more uniform manner across diffuser plate 36. Referring to
FIG. 2, a portion of baffle 34 has been fragged out to illustrate
the perforations within diffuser plate 36. These perforations may
be of the same diameter, or may vary across the face of diffuser
plate 36. Likewise, diffuser plate 36 need not have pass-through
perforations but, rather, may be differently configured to diffuse
the flow of exhaust gases and DEF, such as by using a lattice
structure, etc.
[0022] Catalytic reactor 26 may be of conventional design, and is
directly coupled to the downstream side of reduction agent doser
24. Catalytic reactor 26 preferably has a flow path diameter which
is approximately the same as the inside diameter of housing 28.
[0023] During operating, exhaust gases are transported from exhaust
manifold 20, through exhaust conduit 22, to SCR system 12. A DEF is
injected against target plate 32 at a desired flow velocity and
impingement angle. The DEF and exhaust gases flow in a radially
outward direction around target plate 32 and then in a radially
inward direction toward center opening 40 of baffle 34. This
generally serpentine-type flow path provides a sufficient latency
period for adequate mixing of the DEF with the exhaust gases. The
mixed DEF and exhaust gases are diffused by diffuser plate 36 and
flow into catalytic reactor 26 where a catalytic reaction occurs in
known manner.
[0024] In the embodiment of SCR system 12 shown and described
above, the mixing of the DEF with the exhaust gases occurs because
of the mixing time associated with the longer flow path. To further
assist in mixing of the DEF with the exhaust gases, an optional
heater (such as a resistive type heater) 42 (shown in dashed lines
in FIG. 2) may be provided at the rear or face of target plate
32.
[0025] Having described the preferred embodiment, it will become
apparent that various modifications can be made without departing
from the scope of the invention as defined in the accompanying
claims.
* * * * *