U.S. patent application number 11/504148 was filed with the patent office on 2007-02-15 for automotive diesel exhaust hc dosing valve.
Invention is credited to Stephen Bugos, Michael J. Homby.
Application Number | 20070033927 11/504148 |
Document ID | / |
Family ID | 37440881 |
Filed Date | 2007-02-15 |
United States Patent
Application |
20070033927 |
Kind Code |
A1 |
Homby; Michael J. ; et
al. |
February 15, 2007 |
Automotive diesel exhaust HC dosing valve
Abstract
A dosing valve assembly is disclosed for administering a
reducing agent into an exhaust stream within an exhaust manifold of
an internal combustion engine. The dosing valve assembly comprises
a control valve coupled to a source of the reducing agent, a
reducing agent delivery valve constructed and arranged for coupling
to the exhaust manifold to enable a specified quantity of reducing
agent to be administered into the exhaust stream, and an elongated
conduit disposed between the control valve and reducing agent
delivery valve for fluidly communicating reducing agent from the
control valve to the reducing agent delivery valve. The disclosed
arrangement enables the reducing agent delivery valve to be coupled
to the exhaust manifold and the control valve to be displaced from
the reducing agent delivery valve and away from the high
temperature environment associated with the exhaust manifold.
Inventors: |
Homby; Michael J.;
(Williamsburg, VA) ; Bugos; Stephen; (Poquoson,
VA) |
Correspondence
Address: |
SIEMENS CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
170 WOOD AVENUE SOUTH
ISELIN
NJ
08830
US
|
Family ID: |
37440881 |
Appl. No.: |
11/504148 |
Filed: |
August 15, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60708195 |
Aug 15, 2005 |
|
|
|
Current U.S.
Class: |
60/286 ; 60/295;
60/301 |
Current CPC
Class: |
F01N 2610/03 20130101;
F01N 2610/1453 20130101; Y02T 10/24 20130101; F01N 3/36 20130101;
F01N 3/2066 20130101; F01N 3/0821 20130101; Y02T 10/12
20130101 |
Class at
Publication: |
060/286 ;
060/295; 060/301 |
International
Class: |
F01N 3/00 20060101
F01N003/00; F01N 3/10 20060101 F01N003/10 |
Claims
1. A dosing valve assembly for administering a reducing agent into
an exhaust stream within an exhaust manifold of an internal
combustion engine, comprising: a control valve coupled to a source
of the reducing agent; a reducing agent delivery valve constructed
and arranged for coupling to the exhaust manifold to enable a
specified quantity of reducing agent to be administered into the
exhaust stream, the reducing agent delivery valve including an
inlet communicating with an elongated conduit disposed between the
control valve and reducing agent delivery valve for fluidly
communicating reducing agent from the control valve to the reducing
agent delivery valve, whereby, the reducing agent delivery valve
may coupled to the exhaust manifold and the control valve displaced
from the reducing agent delivery valve.
2. The dosing valve assembly recited in claim 1, wherein the
reducing agent delivery valve is a poppet valve.
3. The dosing valve assembly recited in claim 1, wherein the
control valve is an electronic fuel injector.
4. The dosing valve assembly recited in claim 1, wherein the
control valve is coupled to an electronic control unit that signals
the control valve to move between an open and closed fluid flow
condition in response to feedback of NO.sub.x emissions in the
exhaust stream.
5. The dosing valve assembly recited in claim 1, wherein the
elongated conduit is a connecting tube of a length sufficient to
mount the control valve away from a high-temperature environment
associated with the exhaust manifold.
6. The dosing valve assembly recited in claim 2, wherein the poppet
valve comprises a housing, a valve plate, an axially extending
valve stem comprising a flared portion that mates with a valve seat
in the housing, and a spring for normally biasing the valve plate
such that the flared portion resides in the valve seat to prevent
fluid flow from an outlet of the poppet valve.
7. The dosing valve assembly recited in claim 3, wherein the fuel
injector comprises an inlet for coupling to the source of the
reducing agent, electronic means for opening and closing a fluid
flow path through the fuel injector, and an outlet for coupling the
fuel injector to the elongated conduit.
9. A dosing valve assembly for administering a reducing agent into
an exhaust stream within an exhaust manifold of an internal
combustion engine, comprising: an electronic fuel injector coupled
to a source of the reducing agent; a poppet valve constructed and
arranged for coupling to the exhaust manifold to enable a specified
quantity of reducing agent to be administered into the exhaust
stream, the poppet valve including an inlet communicating with an
elongated conduit disposed between the electronic fuel injector and
poppet valve for fluidly communicating reducing agent from the
electronic fuel injector to the poppet valve, whereby, the poppet
valve may coupled to the exhaust manifold and the electronic fuel
injector displaced from the poppet valve.
10. The dosing valve assembly recited in claim 9, wherein the
electronic fuel injector is coupled to an electronic control unit
that signals the electronic fuel injector to move between an open
and closed fluid flow condition in response to feedback of NO.sub.x
emissions in the exhaust stream.
11. The dosing valve assembly recited in claim 9, wherein the
elongated conduit is a connecting tube of a length sufficient to
mount the control valve away from a high-temperature environment
associated with the exhaust manifold.
12. The dosing valve assembly recited in claim 9, wherein the
poppet valve comprises a housing, a valve plate, an axially
extending valve stem comprising a flared portion that mates with a
valve seat in the housing, and a spring for normally biasing the
valve plate such that the flared portion resides in the valve seat
to prevent fluid flow from an outlet of the poppet valve.
13. The dosing valve assembly recited in claim 9, wherein the fuel
injector comprises an inlet for coupling to the source of the
reducing agent, electronic means for opening and closing a fluid
flow path through the fuel injector, and an outlet for coupling the
fuel injector to the elongated conduit.
14. A dosing valve assembly for administering a dose of diesel fuel
as a reducing agent into an exhaust stream within an exhaust
manifold of an internal combustion engine, comprising: a control
valve coupled to a source of diesel fuel; a reducing agent delivery
valve constructed and arranged for coupling to the exhaust manifold
to enable a specified quantity of diesel fuel to be administered
into the exhaust stream, the delivery valve including an inlet
communicating with an elongated conduit disposed between the
control valve and delivery valve for fluidly communicating diesel
fuel from the control valve to the delivery valve, whereby, the
delivery valve may coupled to the exhaust manifold and the control
valve displaced from the delivery valve.
15. The dosing valve assembly recited in claim 14, wherein the
delivery valve is a poppet valve.
16. The dosing valve assembly recited in claim 14, wherein the
control valve is an electronic fuel injector.
17. The dosing valve assembly recited in claim 14, wherein the
control valve is coupled to an electronic control unit that signals
the control valve to move between an open and closed fluid flow
condition in response to feedback of NO.sub.x emissions in the
exhaust stream.
18. The dosing valve assembly recited in claim 14, wherein the
elongated conduit is a connecting tube of a length sufficient to
mount the control valve away from a high-temperature environment
associated with the exhaust manifold.
19. The dosing valve assembly recited in claim 14, wherein the
poppet valve comprises a housing, a valve plate, an axially
extending valve stem comprising a flared portion that mates with a
valve seat in the housing, and a spring for normally biasing the
valve plate such that the flared portion resides in the valve seat
to prevent fluid flow from an outlet of the poppet valve.
20. The dosing valve assembly recited in claim 16, wherein the fuel
injector comprises an inlet for coupling to the source of diesel
fuel, electronic means for opening and closing a fluid flow path
through the fuel injector, and an outlet for coupling the fuel
injector to the elongated conduit.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 60/708,195 entitled "AUTOMOTIVE DIESEL EXHAUST
HC DOSING VALVE," filed Aug. 15, 2005, the contents of which are
hereby incorporated by reference herein in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to a system for
reducing particulates and nitric oxide (NO.sub.x) emissions by
diesel engines, and more particularly, to a novel hydrocarbon (HC)
dosing valve system that eliminates the requirement for water
cooling in a high temperature environment.
BACKGROUND OF THE INVENTION
[0003] Hydrocarbons and NO.sub.x emissions are a direct result of
the combustion process in an internal combustion engine. To reduce
such harmful emissions, catalytic converters are employed to reduce
their toxicity. For gasoline engines, "three-way catalysts" are
used to reduce nitrogen oxides to nitrogen and oxygen
(2NO.sub.x.fwdarw.xO.sub.2+N.sub.2), oxidize carbon monoxide to
carbon dioxide (2CO+O.sub.2.fwdarw.2CO.sub.2); and oxidize
hydrocarbons to carbon dioxide and water:
C.sub.xH.sub.y+nO.sub.2.fwdarw.xCO.sub.2+mH.sub.2O. In the case of
compression ignition or "Diesel" engines, the most commonly
employed catalytic converter is the diesel oxidation catalyst. This
catalyst employs excess O.sub.2 in the exhaust gas stream to
oxidize carbon monoxide to carbon dioxide and hydrocarbons to water
and carbon dioxide. These converters virtually eliminate the
typical odors associated with diesel engines, and reduce visible
particulates, however they are not effective in reducing NO.sub.x
due to excess oxygen in the exhaust gas stream.
[0004] One way of reducing NO.sub.x emissions in a diesel engine
utilizes a Selective Catalytic Reduction Catalyst (SCR) in the
presence of a reducing agent such as ammonia (NH.sub.3) to modify
the engine exhaust. Existing technologies utilize SCR and NO.sub.x
traps or NO.sub.x adsorbers. The ammonia is typically stored on
board a vehicle either in pure form, either as a liquid or gas, or
in a bound form that is split hydrolytically to release the ammonia
into the system.
[0005] An aqueous solution of urea is commonly used as a reducing
agent. The urea is stored in a reducing tank that associated with
the system. A dosing valve disposed on the exhaust manifold
upstream of a catalytic converter meters the delivery of a selected
quantity of urea into the exhaust stream. When the urea is
introduced into the high temperature exhaust, it is converted to a
gaseous phase and the ammonia is released to facilitate reduction
of NO.sub.x. In lieu of ammonia, diesel fuel from the vehicle's
fuel supply can be used as the reducing agent. In this expedient, a
quantity of diesel fuel is administered directly into the exhaust
via the dosing valve.
[0006] In either case, the dosing valve is mounted directly on the
exhaust manifold, and thus operates in a very high temperature
environment that can reach temperatures as high as 600 deg C.
Accordingly, the dosing valve must be cooled to prevent
decomposition or crystallization of the urea prior to delivery into
the exhaust stream and to maintain integrity of the valve assembly.
The problems associated with this high temperature environment have
previously been addressed by water cooling the assembly. However,
this requires specialized plumbing and systems that ultimately
increase costs and reduce reliability.
SUMMARY OF THE INVENTION
[0007] In view of the foregoing, it is an object of the invention
to provide a dosing valve assembly for an internal combustion
engine that eliminates the need for water cooling of the dosing
valve.
[0008] It is a further object of the invention to provide a dosing
valve assembly that provides a control valve that is separated from
a delivery valve mounted on the exhaust manifold to remove the
control valve from the high temperature environment associated with
the exhaust manifold.
[0009] In accordance with aspects of the invention, a dosing valve
assembly is disclosed for administering a reducing agent, such as
for example, diesel fuel, into an exhaust stream within an exhaust
manifold of an internal combustion engine. The dosing valve
assembly comprises a control valve coupled to a source of the
reducing agent, a reducing agent delivery valve constructed and
arranged for coupling to the exhaust manifold to enable a specified
quantity of reducing agent to be administered into the exhaust
stream, and an elongated conduit disposed between the control valve
and reducing agent delivery valve for fluidly communicating
reducing agent from the control valve to the reducing agent
delivery valve. The disclosed arrangement enables the reducing
agent delivery valve to be coupled to the exhaust manifold and the
control valve to be displaced from the reducing agent delivery
valve and away from the high temperature environment associated
with the exhaust manifold.
[0010] In one expedient, a dosing valve assembly for administering
a reducing agent into an exhaust stream within an exhaust manifold
of an internal combustion engine in accordance with the invention
comprises: an electronic fuel injector that operates as a control
valve which is coupled to a source of the reducing agent; a poppet
valve constructed and arranged for coupling to the exhaust manifold
to enable a specified quantity of reducing agent to be administered
into the exhaust stream, the poppet valve including an inlet
communicating with an elongated conduit disposed between the
electronic fuel injector and poppet valve for fluidly communicating
reducing agent from the electronic fuel injector to the poppet
valve, whereby, the poppet valve may coupled to the exhaust
manifold and displaced from the electronic fuel injector. The
electronic fuel injector is coupled to an electronic control unit
that signals the fuel injector to permit or inhibit the flow of
reducing agent to the poppet valve in response to various sensed
parameters.
[0011] These and other advantages of the invention will be apparent
to those of ordinary skill in the art by reference to the following
detailed description and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic of an illustrative reducing agent
dosing system;
[0013] FIG. 2 is a schematic of a dosing valve assembly in
accordance with an aspect of the invention;
[0014] FIG. 3 is a schematic of an exemplary control valve in the
dosing valve assembly in accordance with another aspect of the
invention; and
[0015] FIG. 4 is a schematic of an exemplary reducing agent
delivery valve in the form of a poppet valve in accordance with yet
another aspect of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Embodiments of the invention will be described with
reference to the accompanying drawing figures wherein like numbers
represent like elements throughout. Before embodiments of the
invention are explained in detail, it is to be understood that the
invention is not limited in its application to the details of the
examples set forth in the following description or illustrated in
the figures. The invention is capable of other embodiments and of
being practiced or carried out in a variety of applications and in
various ways. Also, it is to be understood that the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting. The use of "including,"
"comprising," or "having" and variations thereof herein is meant to
encompass the items listed thereafter and equivalents thereof as
well as additional items.
[0017] Referring to FIG. 1, there is depicted a system schematic of
an exemplary reducing agent dosing system 100. Exhaust from a
diesel engine (not shown) is communicated through an exhaust
manifold 102 including a P-trap, which is coupled to a catalytic
converter 104. The catalytic converter 104 is of the SCR type that
is well known in the art, which utilizes a selective catalytic
reduction method to reduce the NO.sub.x content in the exhaust
stream. A reducing agent, such as diesel fuel in the exemplary
embodiment, is introduced into the exhaust manifold via a dosing
valve 106 that is physically attached to manifold 102. The dosing
valve 106 fluidly communicates with a control valve 108 that is
disposed away from manifold 102. The details of the dosing valve
106 and control valve 108 assembly are described in detail below.
The control valve 106 receives a supply of diesel fuel that is
stored in a fuel tank 110 via a pressure regulator 112. A fuel pump
114 supplies diesel fuel under pressure from tank 110 to regulator
112. The fuel pump 114 and the control valve 108 are electrically
coupled to an electronic control unit (ECU) 116. A dosing control
unit (DCU) 118 is disposed between ECU 116 and control valve 108.
These components are operative to meter a quantity of diesel fuel
that is injected into the exhaust stream to reduce the NO.sub.x
content in the exhaust stream. The reduction is effectuated by
introducing a desired quantity of diesel fuel upstream of catalytic
converter 104. Pressure sensors are disposed upstream and
downstream of catalytic converter 104 to enable these parameters to
be communicated to ECU 116 as schematically depicted in FIG. 1. In
addition, temperature sensors and NO.sub.x sensors electrically
communicate with ECU 116 as is known in the art. The ECU 116
monitors various parameters including temperature, pressure and
NO.sub.x content in the exhaust stream and consequently meters the
introduction of diesel fuel into the exhaust stream to optimize the
reduction of undesirable particulates and NO.sub.x emissions.
[0018] FIG. 2 is a schematic of a dosing valve assembly 200, which
generally comprises a control valve assembly 202 and poppet valve
assembly 204. The control valve assembly 202 includes a fuel
injector 206 that, for this application, has been modified to omit
an orifice disk that atomizes a fuel charge that is delivered to an
internal combustion engine in the usual manner. The fuel injector
206 is described in greater detail below. In general terms, the
fuel injector 206 comprises an electronic connector 208 that
couples fuel injector 206 to the ECU 116 and DCU 118 as described
above and depicted in FIG. 1. The fuel injector 206 is disposed on
a bracket 210 for mounting the assembly within the vehicle. A fuel
inlet 212 on a first end of the fuel injector 206 receives a supply
of diesel fuel from fuel tank 110 (FIG. 1). The fuel injector 206
is fluidly coupled to poppet valve assembly 204 through a
connecting tube 214, which has a length sufficient to displace the
control valve assembly 202 from the high temperature environment in
proximity to the exhaust manifold. The poppet valve assembly 204 is
mounted directly on the exhaust manifold and described in further
detail below.
[0019] FIG. 3 is a schematic an exemplary fuel injector 306
(corresponding to 206 in FIG. 2), that may be used as a control
valve for the present invention. Fuel injector 306 extends along a
longitudinal axis A-A between a first injector end 308A and a
second injector end 308B, and includes a valve group subassembly
310 and a power group subassembly 312. The valve group subassembly
310 performs fluid handling functions, e.g., defining a fuel flow
path and prohibiting fuel flow through the injector 306. The power
group subassembly 312 performs electrical functions, e.g.,
converting electrical signals to a driving force for permitting
fuel flow through the injector 306.
[0020] The valve group subassembly 310 includes a tube assembly 314
extending along the longitudinal axis A-A between the first fuel
injector end 308A and the second fuel injector end 308B. The tube
assembly 314 can include at least an inlet tube 316, a non-magnetic
shell 318, and a valve body 320. The inlet tube 316 has a first
inlet tube end 322A proximate to the first fuel injector end 308A.
The inlet tube 316 can be flared at the inlet end 322A into a
flange 322B to retain an O-ring 323. A second inlet tube end 322C
of the inlet tube 316 is connected to a first shell end 324A of the
non-magnetic shell 318. A second shell end 324B of the non-magnetic
shell 318 can be connected to a generally transverse planar surface
of a first valve body end 326A of the valve body 320. A second
valve body end 326B of the valve body 320 is disposed proximate to
the second tube assembly end 308B. A separate pole piece 328 can be
connected to the inlet tube 316 and connected to the first shell
end 324A of the non-magnetic shell 318. The pole piece may comprise
a stainless steel material such as SS 430FR (ASTM A838-00). The
non-magnetic shell 318 can comprise non-magnetic stainless steel,
e.g., 300-series stainless steels such as SS 305 (EN 10088-2), or
other materials that have similar structural and magnetic
properties.
[0021] As shown in FIG. 3, inlet tube 316 is attached to pole piece
328 by weld bead 330. Formed into the outer surface of pole piece
328 are pole piece shoulders 332A, which, in conjunction with
mating shoulders of a bobbin of the coil subassembly, act as
positive mounting stops when the two subassemblies are assembled
together. The inlet tube 316 can be attached to the pole piece 328
at an inner circumferential surface of the pole piece 328.
Alternatively, an integral inlet tube and pole piece can be
attached to the inner circumferential surface of a non-magnetic
shell 318.
[0022] An armature assembly 334 is disposed in the tube assembly
314. The armature assembly 334 includes a first armature assembly
end having a ferromagnetic or armature portion 336 and a second
armature assembly end having a sealing portion. The armature
assembly 334 is disposed in tube assembly 314 such that a shoulder
336A of armature 336 confronts a shoulder 332B of pole piece 328.
The sealing portion can include a closure member 338, e.g., a
spherical valve element, that is moveable with respect to the seat
340 and its sealing surface 340A. The closure member 338 is movable
between a closed configuration (depicted in FIG. 3) and an open
configuration (not shown). In the closed configuration, the closure
member 338 contiguously engages the sealing surface 340A to prevent
fluid flow through the opening. In the open configuration, the
closure member 338 is spaced from the seat 340 to permit fluid flow
through the opening. The armature assembly 334 may also include a
separate intermediate portion 342 connecting the ferromagnetic or
armature portion 336 to the closure member 338. The intermediate
portion or armature tube 342 may be attached to armature 336 and
closure member 338 by weld beads 344, 346, respectively.
[0023] Surface treatments can be applied to at least one of the end
portions 332B and 336A to improve the armature's response, reduce
wear on the impact surfaces and variations in the working air gap
between the respective end portions 332B and 336A. The surface
treatments can include coating, plating or case-hardening. Coatings
or platings can include, but are not limited to, hard chromium
plating, nickel plating or keronite coating. Case hardening on the
other hand, can include, but is not limited to, nitriding,
carburizing, carbo-nitriding, cyaniding, heat, flame, spark or
induction hardening.
[0024] Fuel flow through the armature assembly 334 is facilitated
by at least one axially extending through-bore 336B and at least
one aperture 342A through a wall of the armature assembly 334. The
apertures 342A, which can be of any shape, are preferably
non-circular, e.g., axially elongated, to facilitate the passage of
gas bubbles. The apertures 342A provide fluid communication between
the at least one through-bore 336B and the interior of the valve
body 320. Thus, in the open configuration, fuel can be communicated
from the through-bore 336B, through the apertures 342A and the
interior of the valve body 320, around the closure member 338, and
through outlet end 308B of injector 306.
[0025] In another embodiment, a two-piece armature having an
armature portion directly connected to a closure member can be
utilized. Although both the three-piece and the two-piece armature
assemblies are interchangeable, the three-piece armature assembly
is preferable due to its ability to reduce magnetic flux leakage
from the magnetic circuit of the fuel injector 306. It will be
appreciated by those skilled in the art that the armature tube 342
of the three-piece armature assembly can be fabricated by various
techniques, for example, a plate can be rolled and its seams welded
or a blank can be deep-drawn to form a seamless tube.
[0026] In the case of a spherical valve element providing the
closure member 338, the spherical valve element can be connected to
the armature assembly 334 at a diameter that is less than the
diameter of the spherical valve element. Such a connection is on
the side of the spherical valve element that is opposite and
contiguous contact with the seat 340. A lower armature assembly
guide 348 can be disposed in the tube assembly 314, proximate the
seat 340, and slidingly engages the diameter of the spherical valve
element. The lower armature assembly guide 348 facilitates
alignment of the armature assembly 334 along the longitudinal axis
A-A.
[0027] A resilient member 350 is disposed in the tube assembly 314
and biases the armature assembly 334 toward the seat 340. A filter
assembly 352 comprising a filter 354 and a preload adjuster 356 is
also disposed in the tube assembly 314. The filter assembly 352
includes a first filter assembly end 352A and a second filter
assembly end 352B. The filter 354 is disposed at one end of the
filter assembly 352 and also located proximate to the first end
308A of the tube assembly 314 and apart from the resilient member
350 while the preload adjuster 356 is disposed generally proximate
to the second end of the tube assembly 314. The preload adjuster
356 engages the resilient member 350 and adjusts the biasing force
of the member 350 with respect to the tube assembly 314. In
particular, the preload adjuster 356 provides a reaction member
against which the resilient member 350 reacts in order to close the
injector 306 when the power group subassembly 312 is de-energized.
The position of the preload adjuster 356 can be retained with
respect to the inlet tube 316 by an interference press-fit between
an outer surface of the preload adjuster 356 and an inner surface
of the tube assembly 314. Thus, the position of the preload
adjuster 356 with respect to the inlet tube 316 can be used to set
a predetermined dynamic characteristic of the armature assembly
334.
[0028] The power group subassembly 312 comprises an electromagnetic
coil 358, at least one terminal 360, a coil housing 362, and an
overmold 364. The electromagnetic coil 358 comprises a wire that
that can be wound on a bobbin 314 and electrically connected to
electrical contacts 368 on the bobbin 314. When energized, the coil
358 generates magnetic flux that moves the armature assembly 334
toward the open configuration, thereby allowing the fuel to flow
through the opening. De-energizing the electromagnetic coil 358
allows the resilient member 350 to return the armature assembly 334
to the closed configuration, thereby shutting off the fuel flow.
The housing, which provides a return path for the magnetic flux,
generally includes a ferromagnetic cylinder surrounding the
electromagnetic coil 358 and a flux washer 370 extending from the
cylinder toward the axis A-A. The flux washer 370 can be integrally
formed with or separately attached to the cylinder. The coil
housing 362 can include holes, slots, or other features to break-up
eddy currents that can occur when the coil 358 is energized.
[0029] The overmold 364 maintains the relative orientation and
position of electromagnetic coil 358, the at least one terminal
360, and the coil housing 362. The overmold 364 includes an
electrical harness connector 370 portion in which a portion of the
terminal 360 is exposed. The terminal 360 and the electrical
harness connector portion 372 can engage a mating connector, e.g.,
part of a wiring harness (not shown), to facilitate connecting
injector 306 to ECU 116 (FIG. 1) for energizing the electromagnetic
coil 358.
[0030] According to a preferred embodiment, the magnetic flux
generated by electromagnetic coil 358 flows in a circuit that
includes pole piece 328, armature assembly 334, valve body 320,
coil housing 306, and flux washer 370. The magnetic flux moves
across a parasitic air gap between the homogeneous material of the
magnetic portion or armature 336 and valve body 320 into the
armature assembly 334 and across a working air gap between end
portions 332B and 336A towards the pole piece 328, thereby lifting
closure member 338 away from seat 340.
[0031] In an illustrative embodiment, wire is wound onto a
preformed bobbin 366 having electrical connector portions 368 to
form a bobbin assembly. The bobbin assembly is inserted into a
pre-formed coil housing 362. To provide a return path for the
magnetic flux between the pole piece 328 and the coil housing 362,
flux washer 370 is mounted on the bobbin assembly.
[0032] In operation, the electromagnetic coil 358 is energized,
thereby generating magnetic flux in the magnetic circuit. The
magnetic flux moves armature assembly 334 (along the axis A-A,
according to a preferred embodiment) towards the integral pole
piece 328, closing the working air gap. Such movement of the
armature assembly 334 separates the closure member 338 from the
seat 340 and allows fuel to flow from the fuel tank 10 (FIG. 1),
through inlet tube 368, through-bore 336B, apertures 342A and valve
body 320, thereafter between seat 340 and closure member 338,
through the opening, and finally through the outlet end 308B and
into connecting tube 214 (FIG. 2). When the electromagnetic coil
358 is de-energized, the armature assembly 334 is biased by the
resilient member 350 to contiguously engage closure member 338
against seat 340, thereby blocking fluid flow through the injector
306.
[0033] FIG. 4 is a schematic an exemplary poppet valve assembly
(PVA) 404 (corresponding to 204 in FIG. 2), that is mounted on the
exhaust manifold to deliver a reducing agent (e.g., diesel fuel)
into the exhaust stream. PVA 404 comprises an inlet 406 having a
threaded portion 408 for attaching the connecting tube 214 (FIG.
2). The inlet 406 receives fuel from the control valve assembly
(see FIG. 3). The fuel is delivered to first chamber 410 defined in
a housing 412 of the poppet valve assembly 404. In the illustrative
embodiment, the housing 412 includes a first portion 414a and
second portion 414b that are joined by welding at 416. Seals may be
provided in the assembly, but are omitted here for clarity. A
moveable valve plate 418 is disposed within housing 412 and
includes at least one aperture 420 to enable fluid flow from first
chamber 410 to a second chamber 422. Valve plate 418 is normally
biased by spring 424 against annular surface 426 bounding first
chamber 410. A valve stem 428 is attached at a first end 430 to
valve plate 418 and is axially elongated along a central axis B-B
to a flared portion 432 at a second end 434. The flared portion has
a surface 436 that is normally biased against a complimentary
surface 438 that defines a valve seat in housing 412 to block fluid
flow through to an outlet end 440 of poppet valve PVA 404. An
orifice plate 442 is disposed in the outlet end 440 to provide for
a uniform distribution of fuel into the exhaust stream as is well
known in the art of fuel injector design. The PVA 404 is mounted on
the exhaust manifold shown generally by the reference numeral 444,
by a clamping assembly (omitted for clarity). In operation, control
valve assembly 306 (FIG. 3), under the control of ECU 116/DCU 118,
releases a quantity of fuel to PVA 404 via connecting tube 214
(FIG. 2). The fuel under pressure biases the valve plate 418
downwardly against the force of spring 424, thereby enabling a
quantity of fuel to flow through aperture(s) 420 into second
chamber 422. The movement of valve plate 418 translates the flared
portion 432 of valve stem 428 away from surface 438, which permits
fuel to flow through the orifice plate 442 and out of the PVA 404
into the exhaust manifold. When the control valve assembly 306
restricts the flow of fuel through the connecting tube 214, the
reduced fuel pressure in first chamber 410 is overcome by the force
of spring 424 to move the valve plate 418 (and stem 428) upwardly
to close off the PVA 404, and the flow of fuel is prevented from
entering the exhaust manifold.
[0034] The foregoing detailed description is to be understood as
being in every respect illustrative and exemplary, but not
restrictive, and the scope of the invention disclosed herein is not
to be determined from the description of the invention, but rather
from the claims as interpreted according to the full breadth
permitted by the patent laws. For example, while the method is
disclosed herein with respect to tubular components of a fuel
injector, the techniques and configurations of the invention may be
applied to other tubular components where a hermetic weld is
required. It is to be understood that the embodiments shown and
described herein are only illustrative of the principles of the
present invention and that various modifications may be implemented
by those skilled in the art without departing from the scope and
spirit of the invention.
* * * * *