U.S. patent application number 12/133803 was filed with the patent office on 2008-12-11 for dispensing system with remotely mounted metering device.
Invention is credited to Matthew P. Hanson, Mary J. Lorenzen, Paul Way.
Application Number | 20080302089 12/133803 |
Document ID | / |
Family ID | 40094598 |
Filed Date | 2008-12-11 |
United States Patent
Application |
20080302089 |
Kind Code |
A1 |
Way; Paul ; et al. |
December 11, 2008 |
Dispensing System with Remotely Mounted Metering Device
Abstract
A system is disclosed for dispensing a reactant into an exhaust
stream. The system dispenses a mixture of reactant and pressurized
air into the exhaust stream. This system includes a mixing manifold
that mounts to an exhaust pipe that carries the exhaust stream. The
system also includes a metering device remotely mounted from the
mixing manifold.
Inventors: |
Way; Paul; (New Brighton,
MN) ; Hanson; Matthew P.; (Chanhassen, MN) ;
Lorenzen; Mary J.; (Chanhassen, MN) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Family ID: |
40094598 |
Appl. No.: |
12/133803 |
Filed: |
June 5, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60942358 |
Jun 6, 2007 |
|
|
|
Current U.S.
Class: |
60/286 |
Current CPC
Class: |
F01N 2610/03 20130101;
F01N 2610/11 20130101; F01N 2610/1453 20130101; F01N 3/0253
20130101; F01N 2610/08 20130101; F01N 3/36 20130101 |
Class at
Publication: |
60/286 |
International
Class: |
F01N 9/00 20060101
F01N009/00 |
Claims
1. A system for dispensing a reactant into an exhaust stream, the
system comprising: a manifold defining a mixing chamber, an air
passage that extends to the mixing chamber, a reactant passage that
extends to the mixing chamber, and a cooling passage for
circulating a liquid cooling fluid through the manifold; a mixed
air/reactant outlet in fluid communication with the mixing chamber;
and a metering device for controlling the flow of reactant to the
reactant passage, the metering device being remotely mounted from
the manifold and connected to the reactant passage by a reactant
line.
2. The system of claim 1, further comprising a check valve
positioned at the reactant passage.
3. The system of claim 2, wherein the check valve ensures that the
reactant line remains full of reactant even when the metering
device is not dispensing reactant.
4. The system of claim 1, wherein the metering device includes a
valve that is opened and closed based on input from an electronic
control unit.
5. The system of claim 1, wherein the metering device includes a
fuel injector.
6. The system of claim 1, wherein the metering device includes a
spool valve.
7. The system of claim 1, wherein the mixed air/reactant outlet
includes a dispensing tube having an end that mounts within a mixed
reactant/air passage of the manifold, and wherein the cooling
passage is generally u-shaped and loops around the mixed
reactant/air passage.
8. The system of claim 1, further comprising a dispensing tube that
projects outwardly from the manifold and defines the mixed
air/reactant outlet.
9. The system of claim 8, wherein the dispensing tube defines a
dispensing orifice through a side wall of the dispensing tube.
10. The system of claim 9, wherein the dispensing orifice has a
diameter less than 0.11 inches.
11. The system of claim 10, wherein the dispensing orifice has a
diameter in the range of 0.04 to 0.06 inches.
12. The system of claim 9, wherein the side wall includes an outer
surface aligned at an oblique angle relative to a central axis of
the dispensing tube.
13. The system of claim 12, wherein the dispensing orifice defines
a central axis that is generally perpendicular to the outer surface
of the side wall.
14. The system of claim 7, wherein the manifold includes a
generally rectangular manifold block having a first side positioned
opposite from a second side, and a third side that extends from the
first side to the second side, wherein the dispensing tube projects
outwardly from the first side of the manifold block, wherein a
reactant inlet for accessing the reactant passage is located at the
second side of the manifold block, wherein an air inlet for
accessing the air passage is defined at the third side of the
block, wherein a cooling fluid inlet for accessing the cooling
passage is defined at the third side of the block, and wherein a
cooling fluid outlet for accessing the cooling passage is defined
at the third side.
15. A system for dispensing a reactant into an exhaust stream, the
system comprising: a manifold defining a mixing chamber, an air
passage that extends to the mixing chamber, a reactant passage that
extends to the mixing chamber; a mixed air/reactant outlet in fluid
communication with the mixing chamber; a metering device for
controlling the flow of reactant to the reactant passage, the
metering device being remotely mounted from the manifold and
connected to the reactant passage by a reactant line; and a check
valve positioned at the reactant passage, wherein the check valve
ensures that the reactant line remains full of reactant even when
the metering device is not dispensing reactant.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/942,358, filed Jun. 6, 2007, which
application is hereby incorporated by reference in its
entirety.
TECHNICAL FIELD
[0002] The present disclosure relates generally to systems for
dispensing a reactant into a diesel engine exhaust system.
BACKGROUND
[0003] Vehicles equipped with diesel engines may include exhaust
systems that have diesel particulate filters for removing
particulate matter from the exhaust stream. With use, soot or other
carbon-based particulate matter accumulates on the diesel
particulate filters. As particulate matter accumulates on the
diesel particulate filters, the restriction of the filters
increases causing the buildup of undesirable back pressure in the
exhaust systems. High back pressures decrease engine efficiency.
Therefore, to prevent diesel particulate filters from becoming
excessively loaded, diesel particulate filters should be regularly
regenerated by burning off (i.e., oxidizing) the particulates that
accumulate on the filters. To initiate regeneration, some prior art
systems inject a hydrocarbon based fuel into the exhaust stream at
a location upstream from the diesel particulate filter. The system
disclosed at PCT application PCT US04/18536, filed Jun. 10, 2004,
entitled Method of Dispensing Fuel into Transient Flow of an
Exhaust System, that is hereby incorporated by reference in its
entirety, includes a catalytic converter positioned upstream from a
diesel particulate filter. In this system, fuel is injected into
the exhaust stream at a location upstream from the catalytic
converter. The injected fuel is combusted at the catalytic
converter to generate heat for regenerating the diesel particulate
filter. In other systems, fuel is injected into the exhaust stream
immediately upstream from the diesel particulate filter such that
combustion of the fuel at the diesel particulate filter provides
heat for regenerating the diesel particulate filter.
[0004] In addition to particulate filters for removing particulate
matter, exhaust systems can be equipped with structures for
removing other undesirable emissions such as carbon monoxide (CO),
hydrocarbons (HC), and nitrogen oxides (NOx). Catalytic converters
are typically used to remove CO and HC. NOx can be removed by
structures such as lean NOx catalysts, selective catalytic
reduction (SCR) catalysts and lean NOx traps.
[0005] Lean NOx catalysts are catalysts capable of converting NOx
to nitrogen and oxygen in an oxygen rich environment with the
assistance of low levels of hydrocarbons. For diesel engines,
hydrocarbon emissions are too low to provide adequate NOx
conversion, thus hydrocarbons are required to be injected into the
exhaust stream upstream of the lean NOx catalysts. SCR's are also
capable of converting NOx to nitrogen and oxygen. However, in
contrast to using HC's for conversion, SCR's use reductants such as
urea or ammonia that are injected into the exhaust stream upstream
of the SCR's. NOx traps use a material such as barium oxide to
absorb NOx during lean bum operating conditions. During fuel rich
operations, the NOx is desorbed and converted to nitrogen and
oxygen by catalysts (e.g., precious metals) within the traps.
[0006] What is needed is an improved system for dispensing fuel,
ammonia, urea or other reactants into the exhaust stream of a
diesel engine.
SUMMARY
[0007] The present disclosure relates to a system for delivering a
reactant into the exhaust stream of a diesel engine. A reactant
dosing system dispenses a mixture of reactant and pressurized air
into the exhaust stream. This system includes a mixing manifold
that mounts to an exhaust pipe that carries the exhaust stream. The
system also includes a metering device remotely mounted from the
mixing manifold.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic diagram of a dosing system having
features in accordance with the principles of the present
disclosure;
[0009] FIG. 2 is a schematic view showing the dosing system of FIG.
1 used to meter fuel into the exhaust stream of a diesel
engine;
[0010] FIG. 3 is an exploded, perspective view of a manifold
assembly having features that are examples of inventive aspects in
accordance with the principles of the present disclosure;
[0011] FIG. 4 is a front view of the manifold assembly of FIG.
3;
[0012] FIG. 5 is a top view of the manifold assembly of FIG. 3;
[0013] FIG. 6 is a cross-sectional view taken along section line
6-6 of FIG. 5;
[0014] FIG. 7 is a perspective view of a manifold block used in the
manifold assembly of FIG. 3;
[0015] FIG. 8 is a partially cut-away front view of the manifold
block of FIG. 7;
[0016] FIG. 9 is a bottom view of the manifold block of FIG. 7;
[0017] FIG. 10 is a partially cut-away side view of the manifold
block of FIG. 7;
[0018] FIG. 11 is a top view of the manifold block of FIG. 7;
[0019] FIG. 12 is a cross-sectional view taken along section line
12-12 of FIG. 8;
[0020] FIG. 13 is a cross-sectional view taken along section line
13-13 of FIG. 8;
[0021] FIG. 13A is a detailed view of a portion of FIG. 13;
[0022] FIG. 14 is a cross-sectional view taken along section line
14-14 of FIG. 8;
[0023] FIG. 15 is a perspective view of a dispensing tube that is
part of the manifold assembly of FIG. 3;
[0024] FIG. 16 is a top end view of the dispensing tube of FIG.
15;
[0025] FIG. 17 is a cross-sectional view taken along section line
17-17 of FIG. 16;
[0026] FIG. 18 is a bottom view of the dispensing tube of FIG.
15;
[0027] FIG. 19 is a cross-sectional view taken along section line
19-19 of FIG. 16;
[0028] FIG. 19A is an enlarged view of a lower portion of FIG.
19;
[0029] FIG. 19B is an enlarged view of an upper portion of FIG.
19;
[0030] FIG. 20 is an end view an insert that is part of the
manifold assembly of FIG. 3;
[0031] FIG. 21 is a cross-sectional view taken along section line
21-21 of FIG. 20;
[0032] FIG. 22 is an end view of a nut used to retain the
dispensing tube of FIG. 15 within the manifold block of FIG. 7;
[0033] FIG. 23 is a cross-sectional view taken along section line
23-23 of FIG. 22;
[0034] FIG. 24 is a plan view of a gasket that is part of the
manifold assembly of FIG. 3;
[0035] FIG. 25 is a side view of the gasket of FIG. 24;
[0036] FIG. 26 is an end view of a check valve that is incorporated
into the manifold block of FIG. 7;
[0037] FIG. 27 is a partially schematic side view of the check
valve of FIG. 26;
[0038] FIG. 28 is an end view of a fitting used to connect a fuel
line to the manifold block of FIG. 7;
[0039] FIG. 29 is a side view of the fitting of FIG. 28;
[0040] FIG. 30 is an end view of a fitting representative of
fittings that can be used at the air inlet, the cooling fluid inlet
and the cooling fluid outlet of the manifold block of FIG. 7;
and
[0041] FIG. 31 is a side view of the fitting of FIG. 30.
DETAILED DESCRIPTION
[0042] FIG. 1 illustrates a dosing system 20 having features that
are examples of inventive aspects in accordance with the principles
of the present disclosure. The dosing system 20 includes a fuel
metering device 22, an air assist control unit 24, a mixing
manifold 26 and an electronic control unit 28. The fuel metering
device 22 and the air assist control unit 24 respectively provide
fuel and air to the mixing manifold 26. At the mixing manifold 26,
the fuel and air are mixed and then dispensed (e.g., sprayed) from
a dispensing tube 30 that projects outwardly from the mixing
manifold 26. The fuel metering device 22 is mounted remotely from
the mixing manifold 26 and is connected in fluid communication with
the mixing manifold 26 by a fuel line 32 (e.g., a conduit such as a
pipe, tube or hose). A fuel line check valve 34 is positioned at
the mixing manifold 26. The check valve 34 ensures that the fuel
line 32 remains completely full of fuel even when the fuel metering
device 22 is not dispensing fuel. In this way, when the fuel
metering device 22 begins to dispense fuel, the check valve opens
and fuel is provided immediately to the mixing manifold 26 without
any significant time delay. The mixing manifold 26 also includes a
cooling arrangement to prevent the check valve 34 from overheating
when the dosing system 20 is used for high temperature
applications. The electronic control unit 28 controls the operation
of the fuel metering device 22 and the air assist control unit
24.
[0043] FIG. 2 shows an example application in which the dosing
system 20 can be used. The application includes a diesel engine 36
(e.g., a diesel engine used for a vehicle such as a truck). An air
intake pipe 38 provides intake air to the diesel engine 36. An
exhaust pipe 40 carries diesel exhaust away from the diesel engine
36. A turbo charger 42 compresses the intake air provided to the
diesel engine 36. The turbo charger 42 includes a turbine 44
located in the exhaust pipe 40 and a compressor 46 located in the
air intake pipe 38. An exhaust treatment arrangement 48 is provided
in the exhaust pipe 40 at a location downstream from the turbine
44. In one embodiment, the exhaust treatment arrangement 48 can
include a catalytic converter positioned upstream from a diesel
particulate filter. For such an embodiment, the dosing system 20
can be used to provide fuel that is combusted at the catalytic
converter to provide heat for regenerating the diesel particulate
filter. As disclosed at PCT application PCT US04/18536, the
electronic control unit can control the amount of fuel dispensed to
provide controlled regeneration of the diesel particulate filter.
PCT application PCT US04/18536 also discloses example
configurations for the catalytic converter and the diesel
particulate filter.
[0044] Referring still to FIG. 2, the dosing system 20 is used to
dispense fuel into the exhaust pipe 40 at a location upstream from
the exhaust treatment arrangement 48. As shown in FIG. 2, the
mixing manifold 26 mounts to the exhaust pipe 40 at a location
immediately downstream from the turbo charger turbine 44. In one
embodiment, the mixing manifold 26 is within two feet of the
turbine 44. The fuel metering device 22, the air assist control
unit 24, and the electronic control unit 28 are all remotely
mounted from the mixing manifold 26. In one embodiment, the fuel
metering device 22, the air assist control unit 24 and the
electronic control unit 28 can be remotely mounted from the mixing
manifold 26 (e.g., at other locations beneath the hood of the
vehicle). During operation of the diesel engine 36, the exhaust
stream in the exhaust pipe 40 at a location immediately downstream
from the turbine 44 can reach high temperatures (e.g., greater than
500 degrees Celsius). Since the mixing manifold 26 is mounted to
the exhaust pipe 40, it can be exposed to high temperatures. To
prevent the mixing manifold 26 and its various components from
being damaged by heat, the mixing manifold 26 is preferably
equipped with a cooling arrangement. In one embodiment, the mixing
manifold 26 defines a cooling passage through which a liquid for
cooling the mixing manifold 26 can be pumped. For example, the
cooling passage can be placed in fluid communication with a liquid
cooling circuit 27 of the engine by cooling fluid supply and return
lines 81, 83 such that a cooling liquid (e.g., a water-based
cooling liquid) can be pumped through the cooling passage of the
mixing manifold 26. In other embodiments, other types of cooling
fluids (e.g., fuel) can be pumped through the cooling passage.
[0045] The fuel metering device 22 is in fluid communication with a
source of fuel such as a fuel circuit of the diesel engine 36.
Pressure for driving the fuel in the fuel circuit can be provided
by a fuel pump 37 that provides fuel to the diesel engine 36. It
will be appreciated that the fuel metering device 22 can have any
number of different configurations. In one embodiment, the fuel
metering device 22 can include a fuel injector having a metering
valve that opens to provide fuel to the mixing manifold 26 and
closes to stop the flow of fuel to the mixing manifold 26. This
type of fuel injector typically cycles the metering valve on and
off with the amount of fuel being supplied to the mixing manifold
26 being controlled by the duty cycle of the metering valve (i.e.,
the duration that the valve is cycled on and off). In an
alternative embodiment, the fuel metering device 22 can include a
spool valve that controls the fuel provided to the mixing manifold
26. The spool valve can be moved to a closed position in which fuel
is not directed to the fuel line 32 and instead is directed to a
fuel tank 39 of the vehicle. The spool valve is also capable of
proportionately controlling the fuel flow rate provided to the
mixing manifold 26 dependent upon the linear position of the spool
valve. The electronic control unit 28 interfaces with the fuel
metering device 22 to turn the fuel metering device 22 off and to
control the flow rate of fuel provided to the mixing manifold 26
through the fuel line 32.
[0046] In a preferred embodiment, the fuel metering device 22 is
remotely mounted with respect to the mixing manifold 26. For
example, the fuel metering device 22 can be mounted to the engine
36 adjacent a cool side of the engine. By mounting the fuel
metering device 22 to the cool side of the engine, the fuel
metering device is not exposed to intense heat that can cause
metering valve damage. The less severe operating conditions allow a
wider variety fuel metering devices to be used. Moreover, the lower
temperatures reduce possible safety concerns relating to fuel
leakage.
[0047] Referring back to FIG. 1, the air assist control unit 24
includes an air manifold 50 having an air inlet 52 and an air
outlet 54. The air inlet 52 is in fluid communication with a source
of compressed air 53 (e.g., the compressed air tank of the truck).
The air outlet 54 is connected in fluid communication with the
mixing manifold 26. Preferably, the air assist control unit 24 is
remotely mounted with respect to the mixing manifold 26 and the air
outlet 54 is connected to the mixing manifold 26 by an air line 56
(e.g., a tube, pipe, hose or other conduit). The air assist control
unit 24 also includes a number of additional components mounted to
the air manifold 50. For example, an air filter 58 is mounted to
the air manifold 50 for filtering the compressed air provided from
the source of compressed air 53. Also, a solenoid valve 60 is
mounted to the air manifold 50 for opening and closing fluid
communication between the air inlet 52 and the air outlet 54. The
open or closed state of the solenoid valve 60 is controlled by the
electronic control unit 28. The air assist control unit 24 further
includes a pressure transducer 62 mounted to the air manifold 50
for measuring the pressure of the compressed air provided to the
mixing manifold 26. Pressure readings taken by the transducer 26
are provided to the electronic control unit 28.
[0048] FIGS. 3-14 show various views of the mixing manifold 26. As
best shown at FIG. 3, the mixing manifold 26 includes a generally
rectangular manifold block 70. In one embodiment, the manifold
block 70 can be constructed of a metal material such as stainless
steel. A plurality of holes can be drilled into the block 70 to
define structures such as fluid passages, a mixing chamber, and
fastener receiving openings. As shown at FIG. 3, the manifold block
70 includes a first side 72, a second side 74 positioned opposite
from the first side 72, and a third side 76 that extends from the
first side 72 to the second side 74. The dispensing tube 30
projects outwardly from the first side 72 of the manifold block 70.
The fuel line 32 connects to the manifold block 70 at a fuel inlet
78 located at the second side 74 of the manifold block 70. The air
line 56 connects to the manifold block 70 at an air inlet 80
located at the third side 76 of the manifold block 70. The coolant
supply line 81 connects to the manifold block 70 at a coolant inlet
82 located at the third side 76 of the manifold block 70. The
coolant return line 83 connects to the manifold block 70 at a
coolant outlet 84 located at the third side 76 of the manifold
block 70.
[0049] Referring to FIGS. 3, 5, 6 and 14, the manifold block 70
defines three fastener openings 84 that extend through the manifold
block 70 from the first side 72 to the second side 74. The fastener
openings 84 are adapted to receive fasteners such as bolts 90 (see
FIG. 2) used to secure the manifold block 70 to the exhaust pipe
40. As shown schematically in FIG. 2, a mounting plate base 86 is
secured (e.g., welded) to the exhaust pipe 40. The mounting base 86
defines three tapped openings 88 arranged to align with the
fastener openings 84 of the manifold block 70. By aligning the
fastener openings 84 with the tapped openings 88, bolts 90 can be
inserted through the fastener openings 84 and threaded into the
tapped openings 88 to secure the manifold block 70 to the mounting
base 86. A gasket layer 92 can be mounted between the mounting base
86 and the first side 72 of the manifold block 70. As shown at
FIGS. 24 and 25, the gasket layer 92 defines openings 94 for
allowing the bolts 90 to pass through the gasket layer 92 and an
opening 96 for allowing the dispensing tube 30 to pass through the
gasket layer 92. The gasket layer 92 provides a seal between the
mounting base 86 and the manifold block 70 to prevent exhaust from
leaking from the exhaust pipe 40 at the location where the
dispensing tube 30 enters the exhaust pipe 40.
[0050] Referring to FIGS. 15-19, the dispensing tube 30 is
elongated along an axis 100 and includes a first end 102 positioned
opposite from a second end 104. A central passage 106 extends
through the dispensing tube 30 along the axis 100. The passage 106
has a chamfered portion 108 located adjacent the first end 102 of
the dispensing tube 30. A dispensing orifice 110 extends from the
central passage 106 through a side wall 111 of the dispensing tube
30 at a location adjacent the second end 104 of the dispensing tube
30. In certain embodiments, the dispensing orifice 110 has a
diameter of less than about 0.11 inches. In other embodiments, the
dispensing orifice 110 has a diameter of less than about 0.075
inches. In further embodiments, the dispensing orifice 110 has a
diameter in the range of 0.04 to 0.06 inches. Of course, other
sized orifices could be used as well. The side wall 111 has an
outer surface 112 that is angled relative to the central axis 100.
The dispensing orifice 110 preferably has an axis 114 that is
generally perpendicular to the outer surface 112 and obliquely
angled relative to the axis 100. The dispensing tube 30 also
includes a retention flange 116 located at the first end 102 of the
dispensing tube 30. In other embodiments, the dispensing tube 30
may be eliminated and the air/fuel mixture can be dispensed through
an outlet defined by the manifold block or may be dispensed through
another type/configuration of dispensing tube, nozzle or
sprayer.
[0051] Referring to FIG. 3, the dispensing tube 30 is part of a
dispensing tube assembly that also includes a washer 120, an insert
piece 122 (see FIGS. 20 and 21) and a retention nut 124 (see FIGS.
22 and 23). The dispensing tube assembly mounts within a mixed
fuel/air passage 126 (see FIGS. 6, 13 and 13A) that extends into
the first side 72 of the manifold block 70. The mixed fuel/air
passage 126 includes a mixing chamber region 126a, a
component-receiving region 126b for receiving the inlet piece 122
and the washer 120, and an internally threaded region 126c
configured to receive the retention nut 124. To assemble the
dispensing tube assembly within the manifold block 70, the inlet
piece 122 and the washer 120 are first inserted within the
component-receiving region 126b of the mixed fuel/air passage 126
with the inset piece 122 seated against a shoulder 127 provided
between the mixing chamber region 126a and the component-receiving
region 126b. Thereafter, the first end 102 of the dispensing tube
30 is inserted into the mixed fuel/air passage 126 and brought into
contact with the washer 120. Next, the retention nut 124 is
inserted over the second end 104 of the dispensing tube 30 and is
threaded into the internally threaded region 126c of the mixed
fuel/air passage 126. As the retention nut 124 is tightened, the
retention nut 124 engages the retention flange 116 of the
dispensing tube 30 such that the insert piece 122 is compressed
against the shoulder 127 and the washer 120 is compressed between
the insert piece 122 and the retention flange 116.
[0052] As best shown at FIGS. 20 and 21, the insert piece 122 has a
cylindrical outer shape having a first end 130 positioned opposite
from a second end 132. A tapered opening 133 (e.g., a truncated
conical opening) extends through the insert piece 122 from the
first end 130 to the second end 132. When the insert piece 122 is
assembled within the passage 126, the first end 130 faces toward
the mixing chamber region 126a of the passage 126 and the second
end 132 engages the washer 120 and aligns with the chamfered
portion 108 of the dispensing tube passage 106.
[0053] Referring to FIGS. 6 and 13, the fuel inlet 78 provides
access to a fuel passage 140 that extends from the second side 74
of the manifold block 70 to the mixing chamber 126b. A check valve
receptacle region 140a of the fuel passage 140 is sized to receive
the check valve 34. An internally threaded region 140b of the fuel
passage 140 is configured to receive a first threaded portion 142
of a fuel inlet fitting 144 (see FIGS. 28 and 29). A countersunk
region 140c of the fuel passage 140 is configured to receive a
washer 146. The fuel inlet fitting 144 also includes a second
threaded portion 143 to which a threaded connector provided on the
fuel line 32 can be connected. The fuel inlet fitting 144 also
includes a wrench flat portion 145 for use in tightening the first
threaded portion 142 within the internally threaded region 140b of
the fuel passage 140. The fuel passage 140 also includes an end
region 140d that provides fluid communication with the mixing
chamber 126b.
[0054] As shown in FIGS. 6, 26, and 27, the check valve 34 includes
a shuttle member 150 that moves within a check valve housing 151 to
open and close fluid communication between the fuel line 32 and the
mixing chamber 126b. A sealing member 153 (e.g., an o-ring seal)
surrounds the valve housing 151 and forms a seal between the
housing 151 and the check valve receptacle region 140a of the fuel
passage 140. An elastomeric valve seat 152 is provided within the
check valve 34. A spring 154 biases the shuttle member 150 against
the valve seat 152. When the fuel metering device 22 is open so as
to direct fuel into the fuel line 32, the shuttle member 150 is
pushed away from the valve seat 152 overcoming the bias of the
spring 154 to allow fuel to pass through the check valve 34 to an
end region 140d of the fuel passage 140. The end region 140d of the
fuel passage 140 is in fluid communication with the mixing chamber
126b of the mixed fuel/air passage 126.
[0055] The air inlet 80 provides access to an air passage 160 that
extends from the third side 76 of the manifold block 70 to the
mixing chamber 126b. The air passage 160 includes a first straight
segment 162, a second straight segment 164, and a third straight
segment 166. As shown at FIG. 10, the first segment 162 includes a
counter sunk region 162a for receiving a washer 168. The first
segment 162 also includes an internally threaded region 162b for
receiving a first threaded portion 170 of a fitting 172 (see FIGS.
30 and 31). The fitting 172 also includes a second threaded portion
174 to which a threaded connector provided at the end of the air
line 56 can be connected. The fitting 172 can include wrench flats
176 for use in tightening the fitting 172 within the internally
threaded region 162b. The first segment 162 further includes an end
region 162c that extends from the internally threaded region 162b
to the second straight segment 164 of the air passage 160.
[0056] As shown at FIGS. 8 and 10, the second straight segment 164
of the air passage 160 extends from the second side 174 of the
manifold block 70, through the end region 162c of the fiber
straight segment 162, to the third straight segment 166. A plug 180
is provided in the second straight segment 164 adjacent the second
side 74 of the manifold block 70 to close the end of the segment
164.
[0057] As shown at FIGS. 8, 10 and 13, the third straight segment
166 of the air passage 160 extends from a fourth side 77 of the
manifold block 70, through the second straight segment 164 and into
the mixing chamber 126b. A plug 182 is provided within the third
straight segment 166 adjacent the fourth side 77 to close the end
of the segment 166.
[0058] Referring to FIG. 12, a generally U-shaped coolant passage
200 extends through the manifold block 70 from the coolant inlet
82, around the mixed air/fuel passage 126 to the coolant outlet 84.
The coolant passage 200 is formed by a first straight segment 202,
a second straight segment 204 and a third straight segment 206. The
first segment 202 extends from the coolant inlet 82 to the second
segment 204. The second segment 204 extends from the fourth side 77
of the manifold block 70 and intersects both the first segment 202
and the third segment 206. A plug 208 is inserted into the second
segment 204 adjacent the fourth side 77 to close the end of the
second segment 204. The third segment 206 extends from the coolant
outlet 84 at the third side 76 of the manifold block 70 to the
second segment 204. Adjacent the third side 76 of the manifold
block 70, the first and third segments 202, 206 define internally
threaded regions 210 into which fittings 212 can be threaded. The
fittings 212 can have a similar configuration to the fitting 172 of
FIGS. 30 and 31.
[0059] In use of the system, when the diesel engine is started,
cooling fluid (e.g., a water-based cooling liquid) is circulated
from the engine water circuit through the cooling passage 200 of
the manifold block 70. The circulation of cooling fluid assists in
maintaining the manifold block 70 at a temperature where
elastomeric components of the check valve 34 are not damaged. This
is particularly significant for applications where the manifold
block 70 is mounted to an exhaust pipe in close proximity to the
diesel engine. When it is desired to supply fuel to the exhaust
stream, the electronic control unit 28 actuates the air assist
control unit 24 and the fuel metering device 22. When the fuel
metering device 22 is actuated to dispense a desired amount of
fuel, the check valve 34 is pushed open thereby allowing fuel to
flow from the fuel line 32 to pass through the fuel passage 140 and
into the mixing chamber 126b. The fuel entering the mixing chamber
126b mixes with air from the air line 56 that is directed into the
mixing chamber 126b via the air passage 160. The mixed air and fuel
flow from the mixing chamber 126b, through the insert piece 122 and
into the passage 106 of the dispensing tube 30. From the passage
106, the mixture of fuel and air is dispensed through the
dispensing orifice 110 into the exhaust stream.
[0060] In the above embodiments, fuel (e.g., a hydrocarbon based
fuel) is injected into the exhaust stream to raise exhaust
temperatures to a target temperature suitable for regenerating a
diesel particulate filter. In other embodiments, the dosing systems
disclosed herein can be used to inject a reactant into an exhaust
stream for other purposes, such as to provide hydrocarbons to
promote the conversion of NOx at a lean NOx catalyst or to provide
hydrocarbons for regenerating NOx traps. In yet other embodiments,
the metering system disclosed herein can be used to dispense a
reductant, such as ammonia or urea, into an exhaust stream for use
with a selective catalytic reduction system for reducing NOx
emissions. A variety of control models or strategies can be used by
the electronic controller to control metering rates for these
alternative systems.
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