U.S. patent application number 13/774520 was filed with the patent office on 2014-08-28 for mounting assembly for reductant injector with thermal isolation and sealing gasket.
This patent application is currently assigned to CATERPILLAR INC.. The applicant listed for this patent is CATERPILLAR INC.. Invention is credited to Richard A. Crandell, Matthew F. Fahrenkrug, Jason W. Hudgens.
Application Number | 20140237998 13/774520 |
Document ID | / |
Family ID | 51386726 |
Filed Date | 2014-08-28 |
United States Patent
Application |
20140237998 |
Kind Code |
A1 |
Fahrenkrug; Matthew F. ; et
al. |
August 28, 2014 |
MOUNTING ASSEMBLY FOR REDUCTANT INJECTOR WITH THERMAL ISOLATION AND
SEALING GASKET
Abstract
A mounting assembly for an injector is located in a curved
portion of an exhaust line having an exhaust flow from an upstream
end to a downstream end. The mounting assembly includes an indent
extending at least partially into the exhaust line curved portion
and disposed in the exhaust flow. The downstream wall has an
interior surface oriented to substantially face the exhaust line
downstream end. A recess extends from the downstream wall in a
direction away from the exhaust line downstream end, and a recess
aperture is formed in the recess and configured to fluidly
communicate with the injector. The recess reduces the amount of
exhaust heat reaching the injector tip.
Inventors: |
Fahrenkrug; Matthew F.;
(Chillicothe, IL) ; Hudgens; Jason W.;
(Washington, IL) ; Crandell; Richard A.; (Holly
Springs, NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CATERPILLAR INC. |
Peoria |
IL |
US |
|
|
Assignee: |
CATERPILLAR INC.
Peoria
IL
|
Family ID: |
51386726 |
Appl. No.: |
13/774520 |
Filed: |
February 22, 2013 |
Current U.S.
Class: |
60/301 ;
123/470 |
Current CPC
Class: |
Y02T 10/24 20130101;
Y02T 10/12 20130101; F01N 2250/02 20130101; F01N 3/035 20130101;
F01N 2610/02 20130101; F01N 3/2066 20130101; F01N 2610/11 20130101;
F01N 2610/1453 20130101 |
Class at
Publication: |
60/301 ;
123/470 |
International
Class: |
F02M 69/04 20060101
F02M069/04 |
Claims
1. An injector mounting assembly for an injector of an engine
exhaust after-treatment system, the injector including a mounting
end having a plurality of mounting feet disposed in spaced
relationship to each other, a tip with a nozzle disposed between
the plurality of mounting feet, and a sealing plate defining a
nozzle opening and mounted to the tip such that the nozzle opening
is aligned with the nozzle, the plurality of mounting feet each
including a distal mounting surface, the injector mounting assembly
comprising: an exhaust line defining a passageway having an
upstream end and a downstream end in fluid communication with the
upstream end, the exhaust line adapted to receive an exhaust flow
from an engine at the upstream end and to discharge the exhaust
flow from the downstream end, the exhaust line including an
exterior surface having a mounting surface with a plurality of
mounting bosses projecting therefrom and a sealing surface defining
an injector passage, the plurality of mounting bosses each
including a distal mounting face, the plurality of mounting bosses
and the injector passage configured such that, when the injector is
mounted to the exhaust line, the distal mounting surface of each of
the plurality of mounting feet is respectively aligned with a
corresponding distal mounting face of the plurality of mounting
bosses and the injector passage is in fluid communication with the
nozzle of the injector such that reductant emitted from the nozzle
of the injector enters the exhaust line and travels in an exhaust
flow direction toward the downstream end; and a gasket mounted to
the exhaust line, the gasket defining a nozzle aperture therein,
the nozzle aperture substantially aligned with the injector passage
of the exhaust line, and the gasket configured such that, when the
injector is mounted to the exhaust line, the gasket is interposed
between the distal mounting surface of each of the plurality of
mounting feet and the corresponding distal mounting face of the
plurality of mounting bosses of the exhaust line, the gasket is
interposed between, and in sealing engagement with, and the sealing
surface of the exhaust line and the sealing plate of the injector,
and the nozzle aperture of the gasket is aligned with the nozzle of
the injector.
2. The injector mounting assembly according to claim 1, wherein the
sealing plate of the injector includes a peripheral flange and an
end face, the end face disposed in axial offset relationship to the
peripheral flange within the injector passage of the exhaust line
and defining the nozzle opening, and wherein the gasket is in
sealing engagement with the peripheral flange of the sealing
plate.
3. The injector mounting assembly according to claim 1, wherein the
plurality of mounting bosses each defines a blind bore therein, the
gasket defines a plurality of fastener apertures, the plurality of
fastener apertures configured in respective alignment with the
blind bore of each of the plurality of mounting bosses.
4. The injector mounting assembly according to claim 3, wherein the
plurality of mounting feet of the injector each defines a through
bore, the plurality of mounting bosses configured such that, when
the injector is mounted to the exhaust line, each through bore of
the plurality of mounting feet is respectively aligned with the
blind bore of one of the plurality of mounting bosses, the injector
mounting assembly further comprising: a plurality of fasteners,
each fastener adapted to extend through the through bore of one of
the plurality of mounting feet and through an associated fastener
aperture of the gasket and to retentively engage the blind bore of
one of the plurality of mounting bosses to mount the injector to
the exhaust line.
5. The injector mounting assembly according to claim 1, wherein the
gasket includes a thermal insulation layer and a shim layer, the
thermal insulation layer comprising an insulative material and
including an injector mating surface, the shim layer configured to
engagingly contact the exhaust line such that the injector mating
surface of the thermal insulation layer is positioned to sealingly
engage the injector and the exhaust line.
6. The injector mounting assembly according to claim 5, wherein the
shim layer comprises a metal.
7. The injector mounting assembly according to claim 5, wherein the
shim layer includes a plurality of plies.
8. The injector mounting assembly according to claim 5, wherein the
sealing surface of the exhaust line is disposed in axial offset
relationship to the distal mounting face of each of the plurality
of mounting bosses of the exhaust line by an axial offset distance,
and the shim layer has a thickness substantially equal to the axial
offset distance.
9. The injector mounting assembly according to claim 5, wherein the
shim layer defines a clearance aperture, the clearance aperture
being larger than the nozzle aperture and circumscribing the nozzle
aperture, the thermal insulation layer including an exhaust line
mating surface, the clearance aperture configured such that a
sealing band is defined on the exhaust line mating surface between
the clearance aperture and the nozzle aperture, the sealing band of
the gasket engaging the sealing surface of the exhaust line.
10. The injector mounting assembly according to claim 9, wherein
the clearance aperture has a clearance diameter, and the nozzle
aperture has a nozzle opening diameter, wherein a ratio of the
clearance diameter to the nozzle opening diameter is at least about
1.5.
11. An engine exhaust after-treatment system comprising: an exhaust
line defining a passageway having an upstream end and a downstream
end in fluid communication with the upstream end, the exhaust line
adapted to receive an exhaust flow from an engine at the upstream
end and to discharge the exhaust flow from the downstream end, the
exhaust line including an exterior surface having a mounting
surface with a plurality of mounting bosses projecting therefrom
and a sealing surface defining an injector passage, the plurality
of mounting bosses each including a distal mounting face; a gasket
mounted to the exhaust line, the gasket defining a nozzle aperture
therein, the nozzle aperture substantially aligned with the
injector passage of the exhaust line; and a reductant injector
mounted to the exhaust line with the gasket interposed
therebetween, the reductant injector including a mounting end
having a plurality of mounting feet disposed in spaced relationship
to each other, a tip with a nozzle disposed between the plurality
of mounting feet, and a sealing plate defining a nozzle opening and
mounted to the tip such that the nozzle opening is aligned with the
nozzle, the plurality of mounting feet each including a distal
mounting surface, the reductant injector mounted to the exhaust
line such that the distal mounting surface of each of the plurality
of mounting feet is respectively aligned with a corresponding
distal mounting face of the plurality of mounting bosses and the
nozzle of the reductant injector extends through the nozzle
aperture of the gasket and is in fluid communication with the
injector passage of the exhaust line such that reductant emitted
from the nozzle of the reductant injector enters the exhaust line
and travels in an exhaust flow direction toward the downstream end;
wherein the gasket is configured such that the gasket is interposed
between the distal mounting surface of each of the plurality of
mounting feet and the corresponding distal mounting face of the
plurality of mounting bosses of the exhaust line, and the gasket is
interposed between, and in sealing engagement with, the sealing
surface of the exhaust line and the sealing plate of the reductant
injector.
12. The engine exhaust after-treatment system according to claim
11, further comprising: a selective catalytic reduction device
disposed in the passageway of the exhaust line downstream of the
reductant injector.
13. The engine exhaust after-treatment system according to claim
12, wherein the sealing plate of the reductant injector includes a
peripheral flange and an end face, the end face disposed in axial
offset relationship to the peripheral flange within the injector
passage of the exhaust line and defining the nozzle opening, and
wherein the gasket is in sealing engagement with the peripheral
flange of the sealing plate.
14. The engine exhaust after-treatment system according to claim
12, wherein the reductant injector is mounted to the exhaust line
by a plurality of fasteners, the plurality of mounting bosses of
the exhaust line each defines a blind bore therein, the gasket
defines a plurality of fastener apertures respectively aligned with
the blind bore of each of the plurality of mounting bosses, the
plurality of mounting feet of the reductant injector each defines a
through bore respectively aligned with one of the plurality of
fastener apertures of the gasket and the blind bore of one of the
plurality of mounting bosses, wherein each fastener extends through
the through bore of one of the plurality of mounting feet and one
of the plurality of fastener apertures of the gasket and
retentively engages the blind bore of one of the plurality of
mounting bosses.
15. The engine exhaust after-treatment system according to claim
12, further comprising: a reductant source in fluid communication
with the reductant injector; a pump adapted to selectively deliver
reductant to the reductant injector from the reductant source.
16. The engine exhaust after-treatment system according to claim
15, further comprising: a particulate filter disposed in the
passageway of the exhaust line upstream of the selective catalytic
reduction device.
17. The engine exhaust after-treatment system according to claim
12, wherein the gasket includes a thermal insulation layer and a
shim layer, the thermal insulation layer comprising an insulative
material and including an injector mating surface, the shim layer
configured to engagingly contact the exhaust line such that the
injector mating surface of the thermal insulation layer is
positioned to sealingly engage the reductant injector and the
exhaust line.
18. The engine exhaust after-treatment system according to claim
17, wherein the sealing surface of the exhaust line is disposed in
axial offset relationship to the distal mounting face of each of
the plurality of mounting bosses of the exhaust line by an axial
offset distance, and the shim layer has a thickness substantially
equal to the axial offset distance.
19. The engine exhaust after-treatment system according to claim
17, wherein the shim layer defines a clearance aperture, the
clearance aperture being larger than the nozzle aperture and
circumscribing the nozzle aperture, the thermal insulation layer
including an exhaust line mating surface, the clearance aperture
configured such that a sealing band is defined on the exhaust line
mating surface between the clearance aperture and the nozzle
aperture, the sealing band of the gasket engaging the sealing
surface of the exhaust line.
20. The engine exhaust after-treatment system according to claim
19, wherein the clearance aperture has a clearance diameter, and
the nozzle aperture has a nozzle opening diameter, wherein a ratio
of the clearance diameter to the nozzle opening diameter is at
least about 1.5.
Description
TECHNICAL FIELD
[0001] This patent disclosure relates, generally, to an engine
exhaust after-treatment system, and, more particularly, to a
mounting assembly for a reductant injector of an engine exhaust
after-treatment system.
BACKGROUND
[0002] Engines, such as, internal combustion engines, including
diesel engines, gasoline engines, gaseous fuel-powered engines, for
example, exhaust a complex mixture including different types of
constituent components, including gaseous compounds, such as
nitrogen oxides (NO.sub.x), and solid particulate matter, also
known as soot. Exhaust emission standards have become increasingly
more stringent, and the amount of NO and soot emitted to the
atmosphere by an engine can be regulated depending on the type of
engine, size of engine, and/or class of engine.
[0003] In order to ensure compliance with the regulation of
NO.sub.x, some engine manufacturers have implemented a strategy
called selective catalytic reduction (SCR). SCR is a process where
a gaseous or liquid reductant, most commonly urea, is injected into
the exhaust stream of an engine and is absorbed onto a substrate.
The reductant reacts with NO in the exhaust gas to form water
(H.sub.2O) and nitrogen (N.sub.2). Although SCR can be effective,
it is most effective when the reductant is maintained below certain
threshold temperatures.
[0004] SCR systems often include an injector for spraying the
reductant. Under unfavorable conditions, the exhaust gas
temperatures at the region where the injector introduces the
reductant into the exhaust can reach more than 500.degree. C. This
high temperature may adversely impact the efficacy of the reductant
injected into the exhaust stream and can harm the injector
itself.
[0005] U.S. Pat. No. 6,513,323 is entitled, "Valve Seat Device For
a Metering Valve of an Exhaust Treatment Station." The '323 patent
is directed to an uncontrolled heat pipe used in a valve seat
device for transferring the waste heat from the exhaust gas acting
on a metering valve to a condensation zone which is situated in a
lower temperature environment, whereby the metering valve is cooled
sufficiently to prevent a chemical change of a reducing agent which
otherwise can be caused by high temperatures.
[0006] It will be appreciated that this background description has
been created by the inventors to aid the reader, and is not to be
taken as an indication that any of the indicated problems were
themselves appreciated in the art. While the described principles
can, in some aspects and embodiments, alleviate the problems
inherent in other systems, it will be appreciated that the scope of
the protected innovation is defined by the attached claims, and not
by the ability of any disclosed feature to solve any specific
problem noted herein.
SUMMARY
[0007] The present disclosure is directed to, in one embodiment, an
injector mounting assembly for an injector of an engine exhaust
after-treatment system. The injector includes a mounting end with a
plurality of mounting feet disposed in spaced relationship to each
other, a tip with a nozzle disposed between the plurality of
mounting feet, and a sealing plate defining a nozzle opening and
mounted to the tip such that the nozzle opening is aligned with the
nozzle. The plurality of mounting feet each includes a distal
mounting surface.
[0008] The injector mounting assembly includes an exhaust line and
a gasket. The exhaust line defines a passageway having an upstream
end and a downstream end in fluid communication with the upstream
end. The exhaust line is adapted to receive an exhaust flow from an
engine at the upstream end and to discharge the exhaust flow from
the downstream end. The exhaust line includes an exterior surface
having a mounting surface with a plurality of mounting bosses
projecting therefrom and a sealing surface defining an injector
passage. The plurality of mounting bosses each includes a distal
mounting face. The plurality of mounting bosses and the injector
passage are configured such that, when the injector is mounted to
the exhaust line, the distal mounting surface of each of the
plurality of mounting feet is respectively aligned with a
corresponding distal mounting face of the plurality of mounting
bosses and the injector passage is in fluid communication with the
nozzle of the injector such that reductant emitted from the nozzle
of the injector enters the exhaust line and travels in an exhaust
flow direction toward the downstream end.
[0009] The gasket is mounted to the exhaust line. The gasket
defines a nozzle aperture therein. The nozzle aperture is
substantially aligned with the injector passage of the exhaust
line. The gasket is configured such that, when the injector is
mounted to the exhaust line: the gasket is interposed between the
distal mounting surface of each of the plurality of mounting feet
and the corresponding distal mounting face of the plurality of
mounting bosses of the exhaust line; the gasket is interposed
between, and in sealing engagement with, the sealing surface of the
exhaust line and the sealing plate of the injector; and the nozzle
aperture of the gasket is aligned with the nozzle of the
injector.
[0010] In another embodiment, an engine exhaust after-treatment
system for a power system of a machine includes an exhaust line, a
gasket mounted to the exhaust line, and a reductant injector
mounted to the exhaust line with the gasket interposed
therebetween. The exhaust line defines a passageway having an
upstream end and a downstream end in fluid communication with the
upstream end. The exhaust line is adapted to receive an exhaust
flow from an engine at the upstream end and to discharge the
exhaust flow from the downstream end. The exhaust line includes an
exterior surface having a mounting surface with a plurality of
mounting bosses projecting therefrom and a sealing surface defining
an injector passage. The plurality of mounting bosses each includes
a distal mounting face.
[0011] The gasket defines a nozzle aperture therein. The nozzle
aperture is substantially aligned with the injector passage of the
exhaust line.
[0012] The reductant injector includes a mounting end having a
plurality of mounting feet disposed in spaced relationship to each
other, a tip with a nozzle disposed between the plurality of
mounting feet, and a sealing plate defining a nozzle opening and
mounted to the tip such that the nozzle opening is aligned with the
nozzle. The plurality of mounting feet each includes a distal
mounting surface. The reductant injector is mounted to the exhaust
line such that the distal mounting surface of each of the plurality
of mounting feet is respectively aligned with a corresponding
distal mounting face of the plurality of mounting bosses and the
nozzle of the reductant injector extends through the nozzle
aperture of the gasket and is in fluid communication with the
injector passage of the exhaust line such that reductant emitted
from the nozzle of the reductant injector enters the exhaust line
and travels in an exhaust flow direction toward the downstream
end.
[0013] The gasket is configured such that the gasket is interposed
between the distal mounting surface of each of the plurality of
mounting feet and the corresponding distal mounting face of the
plurality of mounting bosses of the exhaust line. The gasket is
interposed between, and in sealing engagement with, the sealing
surface of the exhaust line and the sealing plate of the reductant
injector.
[0014] Further and alternative aspects and features of the
disclosed principles will be appreciated from the following
detailed description and the accompanying drawings. As will be
appreciated, the embodiments of an injector mounting assembly and
an engine exhaust after-treatment system for a power system of a
machine disclosed herein are capable of being carried out in other
and different embodiments, and capable of being modified in various
respects. Accordingly, it is to be understood that both the
foregoing general description and the following detailed
description are exemplary and explanatory only and do not restrict
the scope of the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a diagrammatic view of an embodiment of an engine
exhaust after-treatment system constructed in accordance with
principles of the present disclosure.
[0016] FIG. 2 is an enlarged diagrammatic view of the engine
exhaust after-treatment system, illustrating a reductant injector
and a mounting assembly for the injector constructed in accordance
with principles of the present disclosure.
[0017] FIG. 3 is a cross-sectional view taken along line III-III in
FIG. 2 of the exhaust line.
[0018] FIG. 4 is an exploded view of the injector and the injector
mounting assembly of FIG. 2.
[0019] FIG. 5 is a side elevational view, in section, of the
reductant injector and a mounting assembly for the injector of FIG.
2.
[0020] FIG. 6 is an enlarged, detail view taken from FIG. 5.
[0021] FIG. 7 is a perspective view of an embodiment of a reductant
injector suitable for use with principles of the present
disclosure.
[0022] FIG. 8 is a perspective view of an embodiment of a gasket
suitable for use with principles of the present disclosure,
illustrating an injector mating surface of a thermal insulation
layer of the gasket.
[0023] FIG. 9 is a perspective view of the gasket of FIG. 8,
illustrating a shim layer of the gasket.
[0024] FIG. 10 is an enlarged, detail view taken from FIG. 9.
DETAILED DESCRIPTION
[0025] In one aspect of the present disclosure, embodiments of an
injector mounting assembly for an injector of an engine exhaust
after-treatment system suitable for use in a power system are
disclosed herein. In exemplary embodiments described herein, an
engine exhaust after-treatment system includes an exhaust line in
which a mounting assembly for a reductant injector is disposed. The
mounting assembly includes a gasket which can provide thermal
isolation between the exhaust line and the injector and provide a
sealing relationship between the exhaust line and the reductant
injector. Additional features are disclosed which are configured to
protect the injector and related components from high temperatures
generated by the engine exhaust.
[0026] Turning now to the Figures, there is shown in FIG. 1 an
exemplary embodiment of an engine exhaust after-treatment system 10
constructed in accordance with principles of the present
disclosure. The engine exhaust after-treatment system 10 is adapted
to receive an exhaust flow 12 from an engine or power system. In
different embodiments, the engine can be any type of engine (e.g.,
internal combustion, gas, diesel, gaseous fuel, natural gas,
propane, etc.), any suitable size with any number of cylinders, and
in any configuration (e.g., "V," in-line, radial, etc.). The engine
can be used to power any machine or other device, including, for
example, on-highway trucks or vehicles, off-highway trucks or
machines, earth moving equipment, generators, aerospace
applications, locomotive applications, marine applications, pumps,
stationary equipment, or other engine powered applications.
[0027] The engine exhaust after-treatment system 10 can be adapted
to reduce constituents in an exhaust flow 12 from an engine. In
embodiments, the engine exhaust after-treatment system 10 is
adapted to retain and inject a reductant into the exhaust flow 12
of an engine moving through an exhaust passageway defined by an
exhaust line 20 at a location upstream of a catalyst substrate of
an SCR device 14 disposed in the exhaust passageway. In one
example, nitrogen oxide (NO.sub.x) within the exhaust flow 12
passes through the catalyst substrate of the SCR device 14 and
reacts with the reductant to form H.sub.2O and N.sub.2.
[0028] The illustrated engine exhaust after-treatment system 10
includes the SCR device 14 and a reductant system 16. The SCR
device 14 can include a catalyst material disposed on a substrate.
The catalyst material can be adapted to reduce an amount of
NO.sub.x in the exhaust flow 12 by using a reductant 17. The
substrate can be any suitable material, including cordierite,
silicon carbide, other ceramic, or metal. The substrate can include
a plurality of through-going channels and can form a honeycomb
structure. The catalyst substrate can be made from a variety of
materials.
[0029] For example, the catalyst substrate can include a support
material and a metal promoter dispersed within the catalyst support
material. The support material can include, for example, at least
one of alumina, zeolite, aluminophosphates, hexaluminates,
aluminosilicates, zirconates, titanosilicates, and titanates. The
metal promoter can include, for example, silver metal (Ag).
Combinations of these materials can be used and the support
material can be chosen based on the type of fuel used, the
reductant used, the air to fuel-vapor ratio desired, and/or for
conformity with environmental standards. One of ordinary skill in
the art will recognize that numerous other catalyst compositions
can be used without departing from the scope of this
disclosure.
[0030] Further, in other embodiments, multiple catalytic devices
can be included in the engine exhaust after-treatment system 10, if
desired, including multiple SCR devices and reductant injectors.
For example, in embodiments, an ammonia oxidation catalyst (AMOX)
can also be included downstream of the SCR device 14 or zone coated
on the end of the SCR device 14 to help prevent a condition known
as "ammonia slip," which refers to the situation where too much
urea is injected into the exhaust flow 12.
[0031] The reductant can be any suitable material, including, for
example, urea or ammonia, for example. In embodiments, the
reductant 17 can comprise a solution of 32.5% urea in water
commercially-available from BASF Corp. of Florham Park, N.J., under
the trade name Adblue.RTM.. The illustrated reductant 17 comprises
urea, which decomposes into ammonia (NH.sub.3) that is adsorbed or
stored in the SCR device 14.
[0032] The reductant system 16 includes an injector 18 that
introduces the reductant 17 into the exhaust flow 12. The injector
18 can be any suitable injector configured to emit a spray of
reductant therefrom and can include springs, washers, cooling
passages, injector pins, and other features not shown. In
embodiments, the injector 18 can be a dosing module
commercially-available from Robert Bosch GmbH of Germany under the
trade name Denoxtronic.RTM..
[0033] In one example, the SCR device 14 is disposed in the
passageway of the exhaust line 20 downstream of the reductant
injector 18. The reductant 17, such as, urea or a water/urea
mixture, can be sprayed or otherwise advanced into the exhaust flow
12 upstream of the catalyst substrate of the SCR device 14 by the
reductant injector 18 such that the reductant 17 emitted from the
injector 18 enters the exhaust line 20 and travels in an exhaust
flow direction toward the downstream end of the exhaust line 20.
The reductant 17 is absorbed onto the surface of catalyst substrate
of the SCR device 14 where it can react with NO.sub.x (NO and
NO.sub.2) in the exhaust flow 12 to form water (H.sub.2O) and
elemental nitrogen (N.sub.2).
[0034] In embodiments where the reductant 17 is urea, the urea is
decomposed into ammonia (NH.sub.3) and, possibly, other chemical
species, such as isocyanic acid (HNCO) and solid byproducts.
Ammonia may be retained within the SCR device 14. The ammonia
stored in the SCR device 14 can reduce the amount of NO.sub.x in
the exhaust gases passing through the SCR device 14. Other agents
suitable for reducing NO.sub.x can also be injected into the
exhaust flow 12 and/or the SCR device 14 if desired. The use of
urea as a reducing agent precursor for formation of ammonia may be
desirable due to the relative ease of handling urea. In an
exemplary practice, the urea is thermally decomposed into ammonia
and HCNO. The HCNO then reacts with water on the appropriate
catalyst surface (which could be a hydrolysis catalyst or the SCR
catalyst itself) to yield carbon dioxide (CO.sub.2) and additional
ammonia (NH.sub.3). The ammonia, in turn, can act as a reducing
agent within the SCR device 14.
[0035] The use of a hydrolysis catalyst may be desirable to promote
the reaction of HNCO with water. In some embodiments, a hydrolysis
catalyst (H) may be associated with catalyst substrate of the SCR
device 14 to promote even distribution and conversion of urea to
ammonia (NH.sub.3).
[0036] The exhaust flow 12 is introduced to the SCR device 14 via
the exhaust line 20, which is adapted to direct the exhaust flow 12
from the engine through the engine exhaust after-treatment system
10. The exhaust line 20 includes a straight conduit 22 and a curved
conduit or bend 24 upstream of the straight conduit 22. The
injector 18 is mounted in the bend 24. The length of the straight
conduit 22 or distance between the injector 18 and the SCR device
14 can be configured to sufficiently space apart the injector 18
and the SCR device 14 to allow the reductant 17 to disperse into
the exhaust flow 12 and provide a sufficient dwell time for the
reductant 17, including urea, to convert into NH.sub.3.
[0037] The engine exhaust after-treatment system 10 can also
include a diesel oxidation catalyst (DOC) 26, a diesel particulate
filter (DPF) 28, and a clean-up catalyst or other exhaust treatment
devices upstream or downstream of the SCR device 14. The
illustrated engine exhaust after-treatment system 10 shows the DOC
26 upstream of the DPF 28 which, in turn, is upstream of the SCR
device 14 such that the exhaust flow 12 travels in an exhaust flow
direction from the engine through the DOC 26, then through the DPF
28, past the injector 18, and then through the SCR device 14.
[0038] The DOC 26 can be disposed in the passageway of the exhaust
line 20 upstream of the DPF 28 and the SCR device 14. The DOC 26
can be provided to help provide a desired concentration of NO to
NO.sub.2. In embodiments, for example, the reduction process
performed by the catalyst substrate of the SCR device 14 may
perform more effectively when a concentration of NO to NO.sub.2
supplied to the catalyst substrate of the SCR device 14 is about
1:1. In embodiments, the DOC 26 can include a porous ceramic
honeycomb structure or a metal mesh substrate coated with a
material, for example a precious metal, that catalyzes a chemical
reaction to alter the composition of the exhaust. For example, the
DOC 26 can include platinum that facilitates the conversion of NO
to NO.sub.2, and/or vanadium that suppresses the conversion.
[0039] The DPF 28 can be disposed in the passageway of the exhaust
line 20 upstream of the SCR device 14. The DPF 28 can include a
particulate filter adapted to remove soot from the exhaust flow 12
from the engine. It is contemplated that the particulate filter of
the DPF 28 can include an electrically conductive or non-conductive
coarse mesh metal or porous ceramic honeycomb medium. As the
exhaust flow 12 travels through the medium of the DPF 28,
particulates may be blocked by and left behind in the medium. Over
time, the particulates may build up within the medium and, if
unaccounted for, could negatively affect engine performance.
[0040] To minimize negative effects on engine performance, the
collected particulates may be passively and/or actively removed
through a process called regeneration. When passively regenerated,
the particulates deposited on the filtering medium may chemically
react with a catalyst, for example, a base metal oxide, a molten
salt, and/or a precious metal that is coated on or otherwise
included within particulate filter of the DPF 28 to lower the
ignition temperature of the particulates. Because the DPF 28 may be
relatively closely located downstream of the engine, the
temperatures of the exhaust flow 12 entering particulate filter of
the DPF 28 may be high enough, in combination with the catalyst, to
burn away the trapped particulates.
[0041] When actively regenerated, heat may be applied to the
particulates deposited on the filtering medium to elevate the
temperature thereof to an ignition threshold. For this purpose, an
active regeneration device 30 may be proximally located upstream of
the DPF 28. The active regeneration device 30 can be embodied in
the form of a heat source. In embodiments, a combination of passive
and active regeneration may be utilized, if desired.
[0042] To that end, in embodiments, the engine exhaust
after-treatment system 10 can also include a heat source 30 to
regenerate the DPF 28. In embodiments, the heat source 30 can
embody any suitable device configured to produce heat, such as a
burner including a combustion head and a housing to contain a
flame, an electric heating element, a microwave device, or other
heat source. Heat can also be created by injecting a hydrocarbon
source, such as fuel, into the exhaust flow 12 that will
exothermically react in the DOC 26. In embodiments, the heat source
30 can also embody operating the engine under conditions to
generate elevated temperatures in the exhaust flow 12.
[0043] The illustrated DOC 26 and the DPF 28 are housed in a common
first canister 32 of the exhaust line 20. The DOC 26 and the DPF 28
can also be housed in separate canisters in other embodiments. The
SCR device 14 can be housed in a second canister 34 of the exhaust
line 20. The heat source 30, the first canister 32, and the second
canister 34 can be arranged in side-by-side parallel orientation on
a mount 36, as shown in FIG. 1. The heat source 30, the first
canister 32, and the second canister 34 can also be arranged and
mounted in other ways in other embodiments.
[0044] The exhaust line 20 can also include a second bend 38
downstream of the straight conduit 22 for routing the exhaust flow
12 into the second canister 34. In other embodiments, the second
bend 38 can be omitted, and the second canister 34 can be aligned
with the straight conduit 22. The first canister 32 and the second
canister 34 can also include ends 40 for receiving and delivering
the exhaust flow 12 to other portions of the exhaust line 20.
[0045] An additional section of the exhaust line 20 (not shown) can
route the exhaust flow 12 from the heat source 30 to the first
canister 32 receiving end 40. In other embodiments, the heat source
30 can be omitted, and the entering conduit 42 can route the
exhaust flow 12 to the first canister 32 receiving end 40.
[0046] Thus, the exhaust line 20 is adapted to receive the exhaust
flow 12 from an engine at an upstream end 43, direct the exhaust
flow 12 through the engine exhaust after-treatment system 10 to
reduce the amount of NO.sub.x in the exhaust flow 12, and to
discharge the exhaust flow 12 from a downstream end 45. An entering
conduit 42 of the exhaust line 20 can include the upstream end 43
which adapted to receive the exhaust flow 12 from the engine and to
route the exhaust flow 12 through the engine exhaust
after-treatment system 10. The second canister 34, or another end
canister, can include an exit port 44 at a downstream end 45 of the
exhaust line 20 for the exhaust flow 12 to exit the engine exhaust
after-treatment system 10. The downstream end 45 of the exhaust
line 20 is in fluid communication with the upstream end 43 thereof
through the passageway defined by the exhaust line 20.
[0047] The exhaust flow 12 moves downstream in an exhaust flow
direction from the upstream end 43 to the downstream end 45 in a
generally serpentine path. The exhaust flow 12 passes through the
entering conduit 42 and next through the heat source 30, if
included, in a first flow direction 46. The exhaust flow 12 can be
routed to pass through the first canister 32 in a second flow
direction 48 that can be parallel to, and generally opposing, the
first flow direction 46. The exhaust flow 12 passes through the DOC
26, the DPF 28, the end 40 of the first canister 32, and through
the bend 24. The exhaust flow 12 moves past the injector 18 through
the straight conduit 22 in a third flow direction 50 that can be
parallel to, and generally opposing, the second flow direction 48.
The exhaust flow 12 is routed to pass through the second bend 38
and through the second canister 34 in a fourth flow direction 52
that can be parallel to, and generally aligned the second flow
direction 48. Finally, the exhaust flow 12 exits through the exit
port 44 at the downstream end 45 in a fifth flow direction 53 that
is generally perpendicular to the fourth flow direction 52 and
oriented generally vertically upward in the illustrated
position.
[0048] The reductant system 16 can also include a reductant source
54, a pump 56, and a valve 57. The reductant source 54 can be in
fluid communication with the reductant injector 18. The pump 56 can
be adapted to selectively deliver the reductant 17 to the reductant
injector 18 from the reductant source 54. The reductant 17 is drawn
from the reductant source 54 via the pump 56 and delivered to a
reductant inlet connection 58 of the injector 18. The valve 57 or
pump 56 can be used to control the delivery of the reductant
17.
[0049] The reductant system 16 can also include a coolant source 60
in fluid communication with the reductant injector 18. The coolant
source 60 can be adapted to deliver coolant 62 from the coolant
source 60 to the injector 18 and to receive coolant 62 back from
the injector 18 in a closed loop arrangement via coolant port
connections 64 of the injector 18. The coolant source 60 can embody
the coolant system of the engine or another coolant source 60. The
coolant 62 can also be used to cool other parts of the reductant
system 16 or the engine exhaust after-treatment system 10. In
embodiments, the coolant 62 can also be used to thaw the reductant
17 of the reductant source 54 should it freeze.
[0050] In embodiments, the engine exhaust after-treatment system 10
can include a controller in communication with a plurality of
sensors (not shown). For example, a controller and one or more
sensors (not shown) can be included to control the reductant system
16 and/or the heat source 30.
[0051] In embodiments, based on input from each of the sensors, the
controller can be adapted to determine an amount of NO.sub.x being
produced by the engine, a performance parameter of the SCR device
14 (e.g., a reduction efficiency), a history of the performance
parameter (e.g., the reduction efficiency tracked over a period of
time), an amount of the reductant 17 remaining within the reductant
source 54, a history of the supply level of the reductant 17 (e.g.,
the amount of the reductant 17 remaining within the reductant
source 54 tracked over a period of time), and an amount of the
reductant 17 that should be sprayed by reductant injector 18 into
the exhaust flow 12 traveling through the passageway of the exhaust
line 20 to sufficiently reduce the NO.sub.x present within the
exhaust flow 12. The controller can be adapted to regulate the
operation of the reductant injector 18 such that an appropriate
amount of the reductant 17 is sprayed into the exhaust flow 12
upstream of the SCR device 14. In addition, the controller can be
adapted to diagnose deficiencies and/or problems associated with
the exhaust system and to adjust the operation of the engine
exhaust after-treatment system 10, and/or alert an operator
thereof, in response to the diagnosis.
[0052] The controller can embody one or more microprocessors, field
programmable gate arrays (FPGAs), digital signal processors (DSPs),
etc. that include a means for controlling an operation of the power
system in response to signals received from the various sensors.
Numerous commercially-available microprocessors can be configured
to perform the functions of the controller. It should be
appreciated that the controller can readily embody a microprocessor
separate from that controlling other non-exhaust related power
system functions, or that the controller can be integral with a
general power system microprocessor and be capable of controlling
numerous power system functions and modes of operation. If separate
from a general power system microprocessor, the controller of the
engine exhaust after-treatment system 10 can be adapted to
communicate with the general power system microprocessor via data
links or other methods. For example, the controller can be in
communication with an engine control module (ECM) or can be
included in the ECM. Various other known circuits may be associated
with the controller for the engine exhaust after-treatment system
10, including power supply circuitry, signal-conditioning
circuitry, actuator driver circuitry (i.e., circuitry powering
solenoids, motors, or piezo actuators), communication circuitry,
and other appropriate circuitry.
[0053] Referring to FIG. 2, the bend 24 of the exhaust line 20 can
include a bend inlet end 72, a bend outlet end 74, a bend outer
curve 76, a bend inner curve 78, and bend sides 80. The bend outer
curve 76, the bend inner curve 78, and the bend sides 80 form a
bent tube or box structure which is open at the bend inlet end 72
and the bend outlet end 74. The bend inlet end 72 joins to and is
in fluid communication with the end 40 of the first canister 32.
The bend outlet end 74 joins to and is in fluid communication with
the straight conduit 22. The bend outer curve 76, the bend inner
curve 78, and the bend sides 80 constitute walls of the exhaust
line 20 exposed to the exhaust flow 12. Referring to FIGS. 3 and 4,
the bend 24 can also include double walls 82 provided to increase
the thermal protection of the injector 18 from the exhaust flow 12.
The bend outer curve 76 includes an indent portion 83 which is
adapted to define a recess within which the injector 18 can be
mounted as described below.
[0054] An injector mounting assembly 84 for the injector 18 of the
engine exhaust after-treatment system 10 is provided in the bend
outer curve 76. The injector mounting assembly 84 includes the
indent portion 83 of the exhaust line 20. The indent portion 83
includes a downstream wall 86, an upstream wall 88, and sidewalls
90, which together form a recessed pocket or area in the bend 24
(see FIGS. 2 and 3). The indent portion 83 can have a rounded
triangular shape with a width at the upstream end greater than a
width at the downstream end. The indent portion 83 can also have
other shapes, including rectangular, cylindrical, or
hemispherical.
[0055] Referring to FIGS. 2 and 3, the straight conduit 22 includes
an upstream end 92, a downstream end 94 (see FIG. 1), an outer wall
96, an inner wall 98, and sides 100 that form a generally tubular
pipe. The straight conduit 22, and other components, can be wrapped
in insulation 102. The upstream end 92 joins to the bend outlet end
74.
[0056] Referring to FIGS. 2 and 3, the bend 24 has an inlet width
101 and an outlet width 103 where the outlet width 103 is smaller
than the inlet width 101 such that the width of the bend 24
decreases from the bend inlet end 72 to the bend outlet end 74.
Referring to FIG. 3, the bend 24 has an inlet depth 104 and an
outlet depth 106 where the outlet depth 106 is greater than the
inlet depth 104 such that the depth of the bend 24 increases
gradually from the bend inlet end 72 to the bend outlet end 74.
Because the relative sizes of the inlet width 101 to the outlet
width 103 and the inlet depth 104 to the outlet depth 106 vary in
opposite relation, a substantially constant flow area can be
maintained. In other embodiments, the width and the depth of the
bend 24 can be constant or vary differently. The outlet depth 106
and the outlet width 103 can substantially match the width or
diameter of the straight conduit 22.
[0057] Referring to FIG. 3, an axial centerline 108 extends through
the center of the bend 24 and continues through the straight
conduit 22. The indent portion 83 extends into the bend 24 toward
the axial centerline 108 and includes a maximum bend extension
point 110. The maximum bend extension point 110 can be a point or
region where the downstream wall 86 and the upstream wall 88
meet.
[0058] Referring to FIG. 3, the injector 18, when mounted to the
indent portion 83 of the exhaust line 20, is adapted to discharge a
spray 68 of the reductant 17 into the exhaust flow 12. The spray 68
can define an axis of symmetry 70. Absent any influence by the
exhaust flow 12, the axis of symmetry 70 can be substantially
parallel to and aligned with the third flow direction 50 of the
exhaust flow 12 which is headed downstream to the SCR device
14.
[0059] FIG. 3 shows the direction of the exhaust flow 12 as it
travels through the bend 24 into the straight conduit 22. The
direction of the exhaust flow 12 includes a straight inlet
direction 126, a straight outlet direction 128, and a central
curved direction 130 between the straight inlet direction 126 and
the straight outlet direction 128. Also included are blocked flow
areas 132, 134 just upstream of the upstream wall 88 and just
downstream of the downstream wall 86 in the corner where the
downstream wall 86 meets the bend outer curve 76, respectively, of
the indent portion 83.
[0060] The injector 18 can be mounted in the downstream wall 86 so
that the reductant spray 68 is substantially aligned with the axis
of symmetry 70 and the centerline 108 as it extends in the straight
conduit 22. The indent portion 83 can also be sized to locate the
axis of symmetry 70 to intersect with an intermediate direction 136
of the exhaust flow 12. The intermediate direction 136 is the
direction of the exhaust flow 12 as it begins to straighten into
the straight outlet direction 128 from the central curved direction
130. In other embodiments, the injector mounting assembly 84 can be
adapted to mount the injector at a different orientation with
respect to the straight conduit 22 and/or the straight outlet
direction 128 of the exhaust flow 12.
[0061] Referring to FIG. 4, an exemplary embodiment of an injector
mounting assembly 84 for an injector of an engine exhaust
after-treatment system constructed in accordance with principles of
the present disclosure and the reductant injector 18 are shown. The
injector mounting assembly 84 includes the indent portion 83 of the
exhaust line 20, a gasket 140 interposed between the indent portion
83 and the injector 18, and a plurality of fasteners 142 and a
corresponding plurality of washers 143 configured to mount the
reductant injector 18 to the exhaust line 20.
[0062] Referring to FIGS. 4-6, the reductant injector 18 can be
mounted to the exhaust line 20 with the gasket 140 interposed
therebetween. The injector 18 includes a mounting end 145 with a
tip 147 having a nozzle 150 adapted to selectively discharge a
spray 68 of the reductant 17. The reductant inlet connection 58 is
positioned opposite the nozzle 150 at a reductant end 152 of the
injector 18. The reductant inlet connection 58 is in fluid
communication with the nozzle 150 such that the reductant 17 can be
selectively emitted by the injector 18. The reductant injector 18
can be adapted to be selectively operated by an electronic control
module as is known in the art. The injector 18 can include an
internal, electrically-operated valve to permit adjustable
dosing.
[0063] The reductant end 152 of the injector 18 can also include
the coolant port connections 64. The coolant port connections 64
are adapted to fluidly connect the reductant injector 18 to the
coolant source 60 so that coolant 62 can enter the injector 18
through one of the coolant port connections 64, flow through the
injector 18 to cool the injector 18, and exit the injector 18
through the other of the coolant port connections 64 to return the
warmed coolant to the coolant source 60.
[0064] Referring to FIGS. 4 and 7, the mounting end 145 of the
injector 18 can further include a plurality of mounting feet 154
which are configured to permit the injector 18 to be removably
coupled to the exhaust line 20 using the fasteners 142 and the
washers 143. The illustrated injector 18 includes three mounting
feet 154. The mounting feet 154 are disposed in spaced relationship
to each other. The nozzle 150 is disposed between the mounting feet
154 (see FIG. 7). The mounting feet 154 each defines a through bore
156. At the mounting end 145, the mounting feet 154 each includes a
distal mounting surface 158 which circumscribes the through bore
156.
[0065] Referring to FIGS. 4-7, the reductant injector 18 includes a
sealing plate 162 that is removably mounted to the nozzle 150. The
sealing plate 162 defines a nozzle opening 164 and can be mounted
to the tip 147 such that the nozzle opening 164 is aligned with the
nozzle 150.
[0066] Referring to FIG. 6, the sealing plate 162 includes a
peripheral flange 166 and an end face 168. The end face 168 defines
the nozzle opening 164. The peripheral flange 166 of the sealing
plate 162 can be placed in sealing engagement with the gasket 140
when the reductant injector 18 is mounted to the exhaust line 20
with the gasket 140 interposed therebetween. The end face 168 of
the sealing plate 162 is disposed in axial offset relationship to
the peripheral flange 166, being separated by an axial offset
distance 170. The axial offset relationship between the end face
168 and the peripheral flange 166 permits the end face 168 to be
disposed within an injector passage 175 of the exhaust line 20. The
gasket 140 is in sealing engagement with the peripheral flange 166
of the sealing plate 162.
[0067] Referring to FIGS. 5 and 6, the tip 147 can include a
mounting surface 177 which is generally annular and circumscribes
the nozzle 150. The mounting surface 177 of the tip 147 is adapted
to be placed in engagement with the peripheral flange 166 of the
sealing plate 162. The distal mounting surfaces 158 of the mounting
feet 154 and the mounting surface 177 of the of the tip 147 of the
injector 18 can define an injector mounting plane 180 can terminate
at a plane that is positioned adjacent the nozzle 150. The end face
168 is disposed in offset relationship with respect to the injector
mounting plane 180 by an axial nozzle distance 182.
[0068] Referring to FIGS. 4 and 5, the injector 18 includes a heat
shield 186 configured to help thermally isolate the injector 18
from the exhaust line 20. The heat shield 186 projects from the
body of the injector 18 and includes a flange 188 that extends
beneath the coolant port connections 64.
[0069] Referring to FIGS. 4-6, the indent portion 83 of the exhaust
line 20 can be configured to protect the injector 18 from the high
temperatures of the exhaust flow 12 while reducing recirculation
flow in the passageway, to thereby help prevent deposits of the
reductant 17 from forming. Referring to FIG. 4, the indent portion
83 of the exhaust line 20 includes an exterior surface 200 having a
mounting surface 202 with a plurality of mounting bosses 204, 205,
206 projecting therefrom and a sealing surface 210 defining the
injector passage 175. The plurality of mounting bosses 204, 205,
206 each includes a distal mounting face 214, 215, 216. Each
mounting boss 204, 205, 206 defines a blind bore 218, 219, 220
which is open to the respective distal mounting face 214, 215, 216.
Each blind bore 218, 219, 220 can include an internal threaded
surface adapted to threadingly engage one of the fasteners 142.
[0070] Referring to FIGS. 4-6, the plurality of mounting bosses
204, 205, 206 are positioned to align with a corresponding one of
the mounting feet 154 of the injector 18. The plurality of mounting
bosses 204, 205, 206 and the injector passage 175 are configured
such that, when the injector 18 is mounted to the exhaust line 20,
the distal mounting surfaces 158 of the mounting feet 154 are
respectively aligned with the corresponding distal mounting faces
214, 215, 216 of the mounting bosses 204, 205, 206 (see FIG. 6
also). Each through bore 156 of the mounting feet 154 is
respectively aligned with the blind bore 218, 219, 220 of an
associated mounting boss 204, 205, 206. In the illustrated
embodiment, the sealing surface 210 and two of the mounting bosses
205, 206 are included in a common central hub 222 such that the two
mounting bosses 205, 206 are in the form of mounting ears.
[0071] The sealing surface 210 circumscribes the injector passage
175, which is configured to provide fluid communication between the
injector nozzle 150 and the passageway of the exhaust line 20. The
distal mounting faces 214, 215, 216 of the mounting bosses 204,
205, 206 of the exhaust line define an exhaust line mounting plane
230 (see FIG. 6). The sealing surface 210 of the exhaust line 20 is
disposed in axial offset relationship to the exhaust line mounting
plane 230 and the distal mounting faces 214, 215, 216 of the
mounting bosses 204, 205, 206 by a seal surface offset distance
235.
[0072] The injector passage 175 is in fluid communication with the
nozzle 150 of the injector 18 such that the reductant 17 emitted
from the nozzle 150 of the injector 18 enters the exhaust line 20
and travels in an exhaust flow direction 225 toward the downstream
end of the exhaust line 20. The injector passage 175, and therefore
the injector nozzle 150, can be positioned and oriented to promote
mixing of the reductant 17 with the exhaust flow 12 as it traverses
through the exhaust line into the straight conduit 22. Referring to
FIG. 3, in the illustrated embodiment, for example, a center 240 of
the injector passage 175 is positioned above the part of the
centerline 108 in the straight conduit 22, as best shown with the
centerline extension 108a shown in FIG. 3. The injector passage 175
is oriented so that an injector passage centerline 245 is disposed
in offset relationship to the centerline 108 of the straight
conduit 22. For example, the center 240 of the injector passage 175
can be approximately 10 millimeters above the centerline extension
108a. In embodiments, the injector passage centerline 245 can be
disposed at variable positions with respect to the centerline 108
of the straight conduit 22 of the exhaust line 20. For example, in
embodiments, the injector passage centerline 245 can extend at an
angle of approximately five degrees with respect to the centerline
108 of the straight conduit 22. The location and orientation of the
injector passage 175 can be varied to promote the mixing of the
spray 68 of the reductant 17 and the exhaust flow 12.
[0073] Referring to FIGS. 4 and 5, anchor bosses 247, 248 can also
project from the exterior surface 200 of the indent portion 83 to
provide a mounting structure for securing a layer of insulation 249
over an exterior surface 251 of the downstream wall 86 as well as
an exterior surface 253 of the upstream wall 88 (see FIG. 5). The
layer of insulation 249 can be formed of a thermal insulating
material, such as a silicate fiber mat encased with a stainless
steel foil.
[0074] The gasket 140 is provided not only to thermally isolate the
mounting feet 154 of the injector 18 from the mounting bosses 204,
205, 206 of the exhaust line 20, but also to thermally isolate the
tip 147 of the injector 18 from the exhaust line 20 and to provide
a sealing engagement between the sealing plate 162 of the injector
18 and the exhaust line 20. The gasket 140 is adapted to be mounted
to the exhaust line 20. The gasket 140 can be interposed between
the mounting feet 154 of the injector 18 and the mounting bosses
204, 205, 206 of the exhaust line 20 and between the tip 147 of the
injector 18 and the sealing surface 210 of the exhaust line 20 to
further insulate the injector 18 from the heat of the exhaust flow
12 when coupled to the exhaust line 20.
[0075] Referring to FIGS. 8-10, the gasket 140 defines a nozzle
aperture 270 therein. The nozzle aperture 270 has a gasket nozzle
opening diameter 272 that is configured to permit the end face 168
of the sealing plate 162 therethrough. The nozzle aperture 270 is
slightly larger than the injector passage 175 of the exhaust line
(see FIG. 6).
[0076] Referring to FIGS. 8-10, the gasket 140 defines a plurality
of fastener apertures 281, 282, 283. The fastener apertures 281,
282, 283 are configured to receive a respective fastener 142
therethrough. The fastener apertures 281, 282, 283 are arranged to
be in respective alignment with the blind bore 218, 219, 220 of the
mounting bosses 204, 205, 206 of the exhaust line 20.
[0077] The illustrated gasket includes a thermal insulation layer
291 and a shim layer 292. The thermal insulation layer 291 and the
shim layer 292 can be secured together using any suitable
technique. For example, in the illustrated embodiment, the shim
layer 292 include a plurality of mounting clips 294 which can be
bent over the thermal insulation layer 291 to secure the layers
291, 292 together. In other embodiments, other techniques (e.g.,
gluing) can be used.
[0078] The thermal insulation layer 291 can be configured to
sealingly contact the injector 18 and the exhaust line 20. The
thermal insulation layer 291 comprises an insulative material, such
as vermiculite, for example, and includes an injector mating
surface 296. In embodiments, the thermal insulation layer 291 of
the gasket 140 can be formed of a suitable insulative material
having a heat conductivity which is lower than the heat
conductivity of the material of the exhaust line 20. The thermal
insulation layer 291 has an insulation thickness 298.
[0079] The shim layer 292 is configured to engagingly contact the
distal mounting faces 214, 215, 216 of the mounting bosses 204,
205, 206 of the exhaust line 20 such that the thermal insulation
layer 291 is positioned to sealingly engage the injector 18 and the
exhaust line 20. The illustrated shim layer 292 comprises a
metal.
[0080] The illustrated shim layer 292 includes a plurality of plies
301, 302. In embodiments, the outer ply 302 can include the
mounting clips 294, and the inner ply 301 can be formed without
clips.
[0081] The shim layer 292 has a shim thickness 305. In embodiments,
the shim thickness 305 is configured to permit the sealing band 314
of the thermal insulation layer 291 to provide a sealing engagement
with the sealing surface 210 of the exhaust line 20. In
embodiments, the shim thickness 305 is substantially equal to the
seal surface offset distance 235.
[0082] The shim layer 292 defines a clearance aperture 310. The
clearance aperture 310 is larger than the nozzle aperture 270 and
circumscribes the nozzle aperture 270. The clearance aperture 310
is configured such that a sealing band 314 is defined between the
clearance aperture 310 and the nozzle aperture 270 on an exhaust
line mating surface 312 of the insulation layer 291, which is in
opposing relationship to the injector mating surface 296. The
sealing band 314 of the gasket 140 is adapted to engage the sealing
surface 210 of the exhaust line 20. In embodiments, the sealing
band 314 is substantially the same size as the sealing surface 210
of the exhaust line 20. In embodiments, the sealing band 314 is
slightly larger than the sealing surface 210 of the exhaust line 20
such that the gasket 140 can be mounted to the exhaust line 20 with
the sealing band 314 in circumscribing relationship to the sealing
surface 210.
[0083] The clearance aperture 310 has a clearance diameter 318. In
embodiments, a ratio of the clearance diameter 318 to the gasket
nozzle opening diameter 272 is at least about 1.25, and at least
about 1.5 in other embodiments. In other embodiments, ratio of the
clearance diameter 318 to the gasket nozzle opening diameter 272
can be about 1.7. In still other embodiments, a different ratio of
the clearance diameter 318 to the gasket nozzle opening diameter
272 can be used.
[0084] In embodiments, the gasket 140 can omit the shim layer 292
depending upon the configuration of the mounting surfaces between
which it is interposed. For example, in embodiments where the
sealing surface 210 of the exhaust line 20 is disposed in
substantially aligned relationship with the exhaust line mounting
plane 230 and the distal mounting faces 214, 215, 216 of the
mounting bosses 204, 205, 206, the shim layer 292 can be
omitted.
[0085] Referring to FIG. 6, the gasket 140 can be mounted to the
exhaust line 20 such that the nozzle aperture 270 is substantially
aligned with the injector passage 175 of the exhaust line 20. The
gasket 140 is configured such that, when the injector 18 is mounted
to the exhaust line 20, the gasket 140 is interposed between the
distal mounting surfaces 158 of each of the mounting feet 154 and
the corresponding distal mounting faces 214, 215, 216 of the
mounting bosses 204, 205, 206 of the exhaust line 20. The gasket
140 is in sealing engagement with the sealing surface 210 of the
exhaust line 20 and the sealing plate 162 of the injector 18 and
the mounting surface 177 of the tip 147. The tip 147 of the
injector 18 is aligned with the nozzle aperture 270 of the gasket
140, and the nozzle 150 extends through the nozzle aperture 270 of
the gasket 140.
[0086] Referring to FIGS. 4-6, each fastener is adapted to extend
through the through bore 156 of one of the mounting feet 154 and
through an associated fastener aperture 281, 282, 283 of the gasket
140 and to retentively engage the blind bore 218, 219, 220 of the
associated mounting boss 204, 205, 206 to mount the injector 18 to
the exhaust line 20. One of the washers 143 can be associated with
each fastener 142 to enhance the retentive engagement between the
injector 18 and the exhaust line 20.
INDUSTRIAL APPLICABILITY
[0087] Embodiments of an injector mounting assembly 84 and an
engine exhaust after-treatment system 10 for a power system of a
machine are described herein. The industrial applicability of
embodiments of an injector mounting assembly 84 and an engine
exhaust after-treatment system 10 for a power system of a machine
constructed according to principles of the present disclosure will
be readily appreciated from the foregoing discussion. The described
principles are applicable for use in multiple embodiments of a
machine, including on-highway trucks or vehicles, off-highway
trucks or machines, earth moving equipment, generators, aerospace
applications, locomotive applications, marine applications, pumps,
stationary equipment, or other engine powered applications
[0088] In embodiments, the injector mounting assembly 84 for an
injector 18 of an engine exhaust after-treatment system 10 can help
prevent overheating of the injector tip 147 by removing the
injector 18 from direct contact with the exhaust flow 12. The
addition of a gasket 140 under the injector mounting feet 154 and
the sealing area of the injector tip 147 help reduce the
temperature of the injector 18 in the area of internal injector
components that can be sensitive to high temperatures (e.g., an
injector grommet, o-ring, and valve filter). In embodiments, a
gasket 140 constructed in accordance with principles of the present
disclosure not only thermally isolates the mounting feet 154 of the
injector 18 from the mounting bosses 204, 205, 206 of the exhaust
line 20, but also thermally isolates and sealingly engages a
sealing area of an injector tip 147 to thereby help reduce injector
temperatures.
[0089] The reductant injector 18 can be exposed to high temperature
during hot shutdowns. The addition of a gasket 140 under the
injector mounting feet 154 and the sealing area of the injector tip
147 can help prevent the temperatures of the injector 18 from
exceeding target temperature limits after a hot shutdown without
the need to follow complicated shutdown procedures. The added
thermal protection provided by following principles of the present
disclosure can help avoid the need to employ additional delayed
engine shutdown strategies to meet target injector temperature
limits. The gasket 140 can help to thermally isolate the injector
18 from the exhaust line 20 and to provide a seal to help prevent
hot exhaust from leaking from the mounting assembly 84.
[0090] Additional measures, such as the configuration of the
injector passage 175 and the layer of insulation 249 and the gasket
140 provide additional thermal isolation of the injector 18 from
the exhaust flow 12. For example, in embodiments, the injector
passage 175 moves the injector 18 by a recess distance away from
the exhaust flow, such as approximately twelve to twenty-five
millimeters, thereby to reduce the heat to the injector tip 147 due
to direct exposure of the injector 18 to the high temperatures of
the exhaust flow 12.
[0091] It will be appreciated that the foregoing description
provides examples of the disclosed system and technique. However,
it is contemplated that other implementations of the disclosure can
differ in detail from the foregoing examples. All references to the
disclosure or examples thereof are intended to reference the
particular example being discussed at that point and are not
intended to imply any limitation as to the scope of the disclosure
more generally. All language of distinction and disparagement with
respect to certain features is intended to indicate a lack of
preference for the features of interest, but not to exclude such
from the scope of the disclosure entirely unless otherwise
specifically indicated.
[0092] Recitation of ranges of values herein are merely intended to
serve as a shorthand method of referring individually to each
separate value falling within the range, unless otherwise indicated
herein, and each separate value is incorporated into the
specification as if it were individually recited herein. All
methods described herein can be performed in any suitable order
unless otherwise indicated herein or otherwise clearly contradicted
by context.
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