U.S. patent application number 11/731913 was filed with the patent office on 2007-08-16 for fuel injector with a metering assembly having a seat molded to a polymeric support member.
Invention is credited to Michael J. Hornby.
Application Number | 20070187532 11/731913 |
Document ID | / |
Family ID | 34710211 |
Filed Date | 2007-08-16 |
United States Patent
Application |
20070187532 |
Kind Code |
A1 |
Hornby; Michael J. |
August 16, 2007 |
Fuel injector with a metering assembly having a seat molded to a
polymeric support member
Abstract
A fuel injector is described that includes a polymeric housing,
pole piece, filter assembly, coil assembly, spring member, armature
assembly and metering assembly. The polymeric housing has a
passageway extending between an inlet and an outlet along a
longitudinal axis. The pole piece is disposed in the passageway.
The metering assembly is secured to the polymeric housing proximate
the outlet. The metering assembly has an 0-ring disposed between a
seat molded to a polymeric support member. The polymeric support
member includes a peripheral portion bonded to the polymeric
housing proximate the outlet. A method of sealing a fuel injector
outlet end is described.
Inventors: |
Hornby; Michael J.;
(Williamsburg, VA) |
Correspondence
Address: |
SIEMENS CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
170 WOOD AVENUE SOUTH
ISELIN
NJ
08830
US
|
Family ID: |
34710211 |
Appl. No.: |
11/731913 |
Filed: |
April 2, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11014691 |
Dec 20, 2004 |
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11731913 |
Apr 2, 2007 |
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60531206 |
Dec 19, 2003 |
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Current U.S.
Class: |
239/585.4 ;
239/575; 239/585.1; 239/900; 239/DIG.19 |
Current CPC
Class: |
B29C 66/71 20130101;
B29C 65/565 20130101; F02M 61/166 20130101; F02M 61/18 20130101;
B29C 65/1683 20130101; B29C 66/71 20130101; F02M 51/0625 20130101;
B29C 65/1677 20130101; F02M 61/12 20130101; B29C 65/72 20130101;
B29C 66/73921 20130101; F02M 2200/8061 20130101; B29C 65/1616
20130101; F02M 51/005 20130101; B29C 66/71 20130101; F02M 51/0667
20130101; B29C 66/65 20130101; B29C 66/7212 20130101; F02M 51/0682
20130101; B29C 66/919 20130101; B29C 66/7212 20130101; B29C 66/71
20130101; B29C 66/5344 20130101; B29C 66/71 20130101; B29C 66/71
20130101; B29C 65/1635 20130101; F02M 61/1853 20130101; B29C
65/1654 20130101; B29C 66/12469 20130101; F02M 61/188 20130101;
F02M 61/168 20130101; B29C 65/1609 20130101; B29C 66/71 20130101;
B29K 2027/16 20130101; B29K 2067/006 20130101; B29K 2309/08
20130101; B29K 2077/00 20130101; B29K 2033/12 20130101; B29K
2023/12 20130101; F02M 61/165 20130101; B29K 2023/00 20130101; F02M
2200/9015 20130101; B29C 66/12441 20130101; F02M 51/0664
20130101 |
Class at
Publication: |
239/585.4 ;
239/585.1; 239/900; 239/575; 239/DIG.019 |
International
Class: |
F02M 51/00 20060101
F02M051/00 |
Claims
1. A fuel injector comprising: a polymeric housing having a
passageway extending between an inlet opening and an outlet opening
along a longitudinal axis; a pole piece disposed in the passageway,
the pole piece having a through opening; a filter assembly having a
portion disposed in the through opening of the pole piece; a coil
assembly disposed in the polymeric housing to surround the pole
piece; a spring member disposed partly in the pole piece and
including a spring portion contiguous with the portion of the
filter assembly; an armature assembly disposed in the passageway in
a first position confronting the pole piece and in a second
position contiguous to a portion of an end face of the pole piece,
the armature assembly having a closure member; and a metering
assembly secured to the housing proximate the outlet, the metering
assembly comprising a seat and a polymeric support member, the seat
molded to the polymeric support member and the polymeric support
member attached to the polymeric housing such that the polymeric
support member supports the seat relative to the polymeric housing
proximal to the outlet opening in the polymeric housing.
2. The fuel injector of claim 1, wherein the seat comprises a
metallic body having at least one annular flange molded to the
polymeric support member.
3. The fuel injector of claim 2, wherein the metallic body has
first and second annular flanges spaced apart and about the
longitudinal axis to define a pocket for retaining a sealing member
between the seat and the polymeric support member.
4. The fuel injector of claim 1, wherein the polymeric support
member and the seat are insert-molded.
5. The fuel injector of claim 4, wherein the seat comprises a
metallic body.
6. The fuel injector of claim 5, wherein the polymeric housing
comprises a nylon member.
7. The fuel injector of claim 6, wherein the polymeric support
member comprises a nylon member.
8. A method of making a metering assembly at an outlet of a fuel
injector having a polymeric housing extending from an inlet to the
outlet along a longitudinal axis, the method comprising: molding a
metering assembly comprising a seat and a polymeric support member
for the seat, the seat including a peripheral portion molded to the
polymeric support member; and securing the polymeric support member
to the polymeric housing such that the polymeric support member
supports the seat relative to the polymeric housing proximal to the
outlet in the polymeric housing.
9. The method of claim 8, wherein the molding comprises
insert-molding a metallic seat in a mold.
Description
PRIORITY
[0001] This application is a continuation and claims the benefit of
U.S. application Ser. No. 11/014,691, filed Dec. 20, 2004, which
claims the benefit of U.S. Provisional Appl. Ser. No. 60/531,206,
filed Dec. 19, 2003 and entitled "Plastic Bodied Fuel Injector,"
which application is incorporated herein in its entirety into this
application.
BACKGROUND OF THE INVENTION
[0002] Examples of known fuel injection systems use an injector to
dispense a quantity of fuel that is to be combusted in an internal
combustion engine. The quantity of fuel that is dispensed is varied
in accordance with a number of engine parameters such as engine
speed, engine load, engine emissions, etc.
[0003] Known electronic fuel injection systems monitor at least one
of the engine parameters and electrically operate the injector to
dispense the fuel. It is believed that examples of known injectors
use electromagnetic coils, piezoelectric elements, or
magnetostrictive materials to actuate a valve.
[0004] A known fuel injector utilizes a plethora of internal
components such as a metallic inlet tube connected to a valve body
via a non-magnetic shell with a pole piece interposed therebetween.
The inlet tube, valve body, non-magnetic shell and pole piece are
generally affixed to each other after a closure assembly and a
metering assembly are disposed in the valve body. A solenoid coil
is inserted over the assembled components and the entire assembly
is molded into the fuel injector.
[0005] It is believed that one known fuel injector utilizes a
plastic body molded over a solenoid coil to provide a plastic inlet
fuel passage with a metallic valve body being coupled to the
solenoid coil.
[0006] It is believed that another known fuel injector utilizes two
separate subassemblies to form the fuel injector. The first
subassembly can include a complete coil assembly and electrical
connector molded into an outer casing to provide a power group. The
second subassembly can include an inlet tube, pole piece,
non-magnetic shell valve body, closure assembly and metering
assembly affixed together to form a stand alone fuel group. The two
sub-assemblies are formed separately and coupled together to
provide an operable fuel injector.
[0007] While the known fuel injectors are suited to the task of
metering fuel, it is believed that the known fuel injectors may
have certain assembly or component drawbacks that require extensive
manufacturing process to be undertaken to ensure that the injector
are suitable for commercial applications. They can include, for
example, the necessity for multiple seal points between components
to provide leak integrity in the injector and a large number of
manufacturing steps that are undertaken. These seals can be
effectuated by elastomeric seals, such as, O-rings, or multiple
hermetic welds to ensure structural and leak integrity of the known
fuel injectors. Others include the potential manufacturing
difficulties associated with thermal distortion in welding multiple
metallic components at close proximity to each other or the need
for a metal valve body with internal resilient seals for leak
integrity. Yet another drawback can include the utilization of lift
setting components that must be inserted into the valve body of the
fuel injector. Thus, it would be advantageous to reduce or even
eliminate some of these drawbacks.
SUMMARY OF THE INVENTION
[0008] The present invention provides for, in one aspect, a fuel
injector that is believed to reduce or eliminate these drawbacks of
the known fuel injectors while maintaining substantially the same
operative performance. The fuel injector of the present invention
utilizes a minimal number of seal points and is designed so that an
interface between a potential leak point is hermetically sealed by
a polymer-to-polymer seal.
[0009] According to one aspect of the present invention, the fuel
injector includes a polymeric housing, pole piece, filter assembly,
coil assembly, spring member, armature assembly and metering
assembly. The polymeric housing has a passageway extending between
an inlet and an outlet along a longitudinal axis. The pole piece is
disposed in the passageway, the pole piece having a through
opening. The filter assembly has a portion disposed in the through
opening of the pole piece. The coil assembly is disposed in the
polymeric housing to surround the pole piece. The spring member is
disposed partly in the pole piece and including a spring portion
contiguous with the portion of the filter assembly. The armature
assembly is disposed in the passageway in a first position having a
first portion confronting the pole piece and in a second position
having a closure member contiguous to an end face of the pole
piece. The metering assembly has an O-ring disposed between a seat
molded to a polymeric support member. The polymeric support member
includes a peripheral portion bonded to the polymeric housing
proximate the outlet.
[0010] In yet another aspect, the present invention provides for a
method of a method of making a metering assembly at an outlet of a
fuel injector. The method can be achieved by molding a metering
assembly having a seat and a polymeric support member, the seat
including a peripheral portion molded to the polymeric support
member; and securing the polymeric support member to the polymeric
housing.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0011] The accompanying drawings, which are incorporated herein and
constitute part of this specification, illustrate an embodiment of
the invention, and, together with the general description given
above and the detailed description given below, serve to explain
the features of the invention.
[0012] FIG. 1A is a representation of a fuel injector according a
preferred embodiment.
[0013] FIG. 1B is an illustration of a polymeric bodied fuel
injector housing that includes a complete coil assembly.
[0014] FIG. 1C is an illustration of a metering assembly that can
be bonded to the housing of FIG. 1B.
[0015] FIG. 2A illustrates another embodiment of the polymeric
bodied fuel injector.
[0016] FIG. 2B illustrates another metering assembly that can be
bonded to the polymeric bodied fuel injector of FIG. 2A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] FIGS. 1A-1C and 2A-2B illustrate the preferred embodiments
of a fuel injector 100 or 200. Referring to FIGS. 1A, 1B and 2A,
the fuel injector 100 or 200 includes a continuous polymeric
housing 10 extending from an inlet 12 to an outlet 14 along a
longitudinal axis A-A. The polymeric housing 10 includes a
polymeric wall surface 10A that directly faces the longitudinal
axis A-A to define a first passage 16 in which fuel can flow from
the inlet 12. The first passage 16 extends from the inlet 12 to
communicate with a second passage 18 formed-by a plurality of
internally mounted components. The first passage 16 includes the
polymeric bore 10A that extends from a first external seal 20
proximate the inlet 12 to a second external seal 22 proximate an
outlet 14 along the longitudinal axis A-A. Disposed within a
portion of the polymeric bore 10A is a metering assembly 24
proximate the second external seal 22. A closure assembly 26 is
disposed proximate the metering assembly 24, which is coupled to a
rim portion 28 at the outlet end 14 of the polymeric housing 10. A
portion of the closure assembly 26 is disposed in the polymeric
bore 10A and between the first and second external seals 20, 22.
The first passage 16 can be provided with a plurality of stepped
surfaces 30, 32, 34 (FIG. 1B) defining a plurality of diameters for
the polymeric bore 10A. The polymeric bore IOA can also include an
inward (i.e., towards the longitudinal axis A-A) surface to define
a guide surface 36 for a reciprocable closure member. The inward
surface preferably includes a tapered surface 36. The polymeric
housing 10 can be formed from a suitable polymeric material such
as, for example, Nylon 6-6 with about 30 percent glass filler.
[0018] As shown in FIG. 1B, the polymeric housing 10 provides a
complete solenoid coil subassembly that is ready for assembly with
the metering and closure assemblies. In particular, the polymeric
housing 10 includes a solenoid coil assembly 38 disposed within the
polymeric housing 10 so that no part of the coil assembly 38
extends outside the boundary of the polymeric housing 10. The
solenoid coil assembly 38 is connected to at least one electrical
terminal 40 formed on an electrical connector portion 42 of the
polymeric housing 10. The terminal 40 and the electrical harness
connector portion 42 can engage a mating connector, e.g., part of a
vehicle wiring harness (not shown), to facilitate connecting the
injector 100 or 200 to an electrical power supply (not shown) for
energizing the electromagnetic coil 48.
[0019] The coil assembly 38 includes a coil housing 44 disposed
about the longitudinal axis A-A to surround a bobbin 46 and at
least one wire coiled about the bobbin 46 to form an
electromagnetic coil 48. The coil housing 44, which provides a
return path for magnetic flux, generally takes the shape of a
ferro-magnetic cylinder surrounding the electromagnetic coil 48. A
flux washer 50 can abut a top surface of the bobbin 46 so that the
flux washer 50 is in physical contact with the coil housing 44. The
flux washer 50 can be integrally formed with or separately attached
to the coil housing 44. The coil housing 44 can include holes 35,
slots, or other features to break up eddy currents, which can occur
when the coil 48 is de-energized.
[0020] The coil assembly 38 can be preferably constructed as
follows. A plastic bobbin 46 is molded with at least one electrical
contact extending from the bobbin 46 so that the peripheral edge of
the contact can be mated with a contact terminal for electrical
communication between the coil and a power source. A wire for the
electromagnetic coil 48 is wound around the plastic bobbin 46 a
predetermined number of times and connected to the at least one
electrical contact portion. The electromagnetic coil 48 (with
bobbin 46) is placed into the coil housing 44. An electrical
terminal 40, which is pre-bent to a desired geometry, is then
electrically connected to each electrical contact portion provided
on the bobbin 46. Thereafter, the polymeric housing 10 can be
formed by a suitable technique such as, for example, thermoset
casting, compression molding or injection molding. The polymeric
housing 10, e.g., an overmold, provides a structural casing for the
injector 100 or 200 and provides predetermined electrical and
thermal insulating properties. In a preferred embodiment, the
polymeric housing 10 is formed by injection molding around the coil
assembly 38 and the electrical connector 40, i.e., an
insert-molding so that the metering assembly can be affixed to the
polymeric housing 10. The insert-molding hermetically seals the
coil assembly 38 from contamination with fuel flow through the
polymeric fuel passage 16.
[0021] Referring to FIGS. 1A, 1C, 2A and 2B, the metering assembly
24 includes a seat 24A that can be any suitable material such as,
for example, plastic, ceramic or metal, long as it provides a
suitably sealing surface. In the preferred embodiments, the seat
24A is formed of metallic material, and is secured to a polymeric
support member 24B with an elastomeric member 29 disposed in a
circumferential pocket of the seat 24A. That is, as the seat 24A
and the elastomeric member 29 are insert-molded, the elastomeric
member 29 is captured between the seat 24A and the polymeric
molding material that, upon curing of the polymeric material,
becomes polymeric support member 24B. The elastomeric member 29 is
believed to provide a redundant seal in the interface between
dissimilar materials being insert-molded. That is, in the event
that thermal cycling could cause separation in the interface
between the metallic seat and the polymeric support member, the
elastomeric member 29 would be able to maintain a seal
therebetween.
[0022] A metering disc 241 is secured to the metallic seat 24A or
to the polymeric support member 24B. The polymeric support member
24B includes a first pocket 24C (FIGS. 1C and 2B) defined by a
cylindrical wall surface 25A to receive a cup-shaped guide member
24E. The cup-shaped guide member 24E can be formed from a suitable
material such as, for example, polymeric, ceramic or metallic.
Preferably, the guide member 24E is stamped metallic member
press-fitted into the first pocket 24C along wall surface 25A to a
predetermined location with respect to the seat 24A. In FIG. 1A,
the guide member 24E can be located via boss extension 25B formed
in the first pocket 24C. The cup-shaped guide member 24E includes
an aperture disposed about the longitudinal axis A-A and at least
one aperture offset with respect to the longitudinal axis A-A. In
the preferred embodiment of FIGS. 1A and 1C, the polymeric support
member 24B also includes a second pocket 24D defined by an annular
cylindrical portion. The second pocket 24D is configured to receive
the rim portion 28 of the outlet 14 of the polymeric housing 10.
Preferably, the second pocket 24D is configured so that at least a
locational clearance fit to a light press-fit is formed between the
rim portion 28 of the polymeric housing 10 and the inner wall
surface 24F of the annular cylinder and the outer surface 24G of
the inner cylinder of the first pocket 24C.
[0023] Similarly, the outer perimeter of the polymeric support
member 24B of FIG. 2A is preferably configured to provide a
suitable fit, e.g., locational to light press fit, with the inner
surface of the polymeric bore 16.
[0024] The metallic seat 24A can be provided with the polymeric
support member 24B by a suitable technique such as, for example,
insert molding the metallic seat 24A with a suitable polymeric
material. In the preferred embodiment of FIG. 1A, the material used
for the polymeric housing 10 and bobbin 46 is Nylon 6-6 with about
30% by weight glass filler with BASF.RTM. Ultramid A3WG6LT as the
material for the polymeric support member 24B. In the preferred
embodiment of FIG. 2A, the material used for the bobbin 46 and
support member 24B is Nylon 6-6 with about 30% by weight glass
filler with BASF.RTM. Ultramid A3WG6LT as the material for the
housing 10.
[0025] The metallic seat 24A defines a seat orifice 24H generally
centered on the longitudinal axis A-A and through which fuel can
flow into the internal combustion engine (not shown). The seat 24A
includes a sealing surface surrounding the seat orifice 24H. The
sealing surface, which faces the interior of polymeric bore 10A,
can be frustoconical or concave in shape, and can have a finished
or coated surface. A metering disc 24I can be used in connection
with the seat 24A to provide at least one precisely sized and
oriented metering orifice 24J in order to obtain a particular fuel
spray pattern. The precisely sized and oriented metering orifice
24J can be disposed on the center axis of the metering disc 24I or,
preferably, the metering orifice 24J can disposed off-axis, and
oriented in any desirable angular configuration relative to one or
more reference points on the fuel injector 100 or 200. Preferably,
the metallic seat 24A is a stainless steel seat.
[0026] Referring to FIGS. 1A and 2A, the closure assembly 26
includes a pole piece 26A and an armature assembly 26B configured
to be magnetically coupled to the solenoid coil assembly 38 in a
fully assembled fuel injector 100 or 200. The pole piece 26A can be
formed as a cylindrical component with a passage 26A1 extending
through the pole piece 26A. The pole piece 26A can be formed by a
suitable technique such as cast, machined, pin rolled with external
barbs or a combination of these techniques. The pole piece passage
26A1 includes a resilient member 27 disposed in the pole piece
passage 26A1. The outer surface of the pole piece 26A can be
provided with recesses or projections 26A2 to assist in retention
of the pole piece 26A (and any flashing of the polymeric bore in
the recesses) once the pole piece 26A has been press-fitted to a
desired location in the polymeric bore 10A of FIG. 2A.
[0027] A filter assembly 52 with a filter element 52A and an
adjusting tube 52B is also disposed in the polymeric bore 10A. As
shown in FIGS. 1A and 2A, the filter assembly 52 includes a first
end and a second end. The filter element 52A is along a central
portion of the filter assembly 52. The adjusting tube 52B is
disposed in the pole piece passage 26A1. The adjusting tube 52B
engages the resilient member 27 and adjusts the biasing force of
the resilient member 27 with respect to the pole piece 26A. The
filter element 52A is retained at an end of the filter assembly 52
spaced from the adjusting tube 52B portion and outside of the pole
piece passage 26A1 so that a gap between the filter assembly 52 and
the polymeric bore 10A is provided therebetween. In the preferred
embodiments, the adjusting tube 52B provides a reaction member
against which the resilient member 27 reacts in order to close the
armature assembly 26B when the solenoid coil assembly 38 is
de-energized. The position of the adjusting tube 52B can be
retained with respect to the pole piece 26A or the polymeric
housing 10 by an interference fit between an outer surface of the
adjusting tube 52B and an inner surface of the pole piece passage
26A1. Thus, the position of the adjusting tube 52B with respect to
the pole piece 26A can be used to set a predetermined dynamic
characteristic of the armature assembly 26B.
[0028] Referring to FIGS. 1A and 2A, the armature assembly 26B
includes an armature 26C secured to an elongated member 26D, which
is secured to a closure member 26E. The closure member 26E can be
of any suitable shape, such as, for example, cylindrical,
semi-spherical or spherical. In the case of a spherical shaped
closure member 26E, i.e., a spheroidal member, the spheroidal
member can be connected to the elongated member 26D at a diameter
that is less than the diameter of the spheroidal member. Such a
connection would be on side of the spheroidal member that is
opposite contiguous contact with the seat 24A. As noted earlier,
the armature lower guide 24E can be disposed in the first pocket
24C of the polymeric support member 24B, proximate the seat 24A,
and would slidingly engage the outer surface of the spherical
closure member. The lower armature lower guide 24E can facilitate
alignment of the armature assembly 26B along the longitudinal axis
A-A, and can reduce flux leakage to the closure member 26E.
[0029] Alternatively, the armature assembly 26B can be formed by
securing an armature 26C directly to the closure member 26E, as
shown in FIG. 2A. At least one aperture 26F can be formed through a
wall of the elongated member 26D. The apertures 26F, which can be
of any shape, are preferably non-circular, e.g., axially elongated,
to facilitate the passage of gas bubbles. For example, in the case
of a separate armature tube that is formed by rolling a sheet
substantially into a tube, the apertures can be an axially
extending slit defined between non-abutting edges of the rolled
sheet. However, the apertures 26F, in addition to the slit, would
preferably include openings extending through the sheet. The
apertures 26F provide fluid communication between the armature
passage 26G and the fuel inlet passage 16.
[0030] The closure member 26E is movable between a closed
configuration, as shown in FIGS. 1A and 2A, and an open
configuration (not shown). In the closed configuration, the closure
member 26E contiguously engages a seat surface of the metallic seat
24A to prevent fluid flow through the seat orifice 24H. In the open
configuration, the closure member 26E is spaced from the seat
surface to permit fluid flow through the seat orifice 24H.
[0031] A radial end face 26I of the armature 26C is configured to
contact a radial end face 26J of the pole piece 26A when the
armature 26C is moved by magnetic flux generated by the solenoid
coil assembly 38. In the embodiment illustrated in FIG. 1A, the
armature 26C is provided with a deep counterbore 26H to receive the
other end of the preload resilient element 27. In the embodiment
illustrated in FIG. 2A, no counterbore 26H is provided and the end
of the resilient element 27 is configured to abut the radial end
face 26I of the armature 26C.
[0032] In the preferred embodiments illustrated in FIGS. 1A and 2A,
surface treatments can be applied to at least one of the end face
of the pole piece 26A or the armature 26C to improve the armature's
response, reduce wear on the impact surfaces and variations in the
working air gap between the respective end faces. 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 are not limited to, nitriding,
carburizing, carbo-nitriding, cyaniding, heat, flame, spark or
induction hardening.
[0033] The surface treatments will typically form at least one
layer of wear-resistant materials on the respective end faces.
These layers, however, tend to be inherently thicker wherever there
is a sharp edge, such as between junction between the circumference
and the radial end face of either portions. Further, this
thickening effect results in uneven contact surfaces at the
radially outer edge of the end portions. However, by forming the
wear-resistant layers on at least one of the end faces, where at
least one end portion has a surface generally oblique to
longitudinal axis A-A, both end faces can be substantially in even
contact with respect to each other when the solenoid coil assembly
38 is energized.
[0034] Since the surface treatments may affect the physical and
magnetic properties of the ferromagnetic portion of the armature
assembly 26B or the pole piece 26A, a suitable material, e.g., a
mask, a coating or a protective cover, surrounds areas other than
the respective end faces during the surface treatments. Upon
completion of the surface treatments, the material is removed,
thereby leaving the previously masked areas unaffected by the
surface treatments.
[0035] In the preferred embodiment illustrated in FIG. 2A, the
armature 26C is formed by stamping a cylindrical workpiece of a
generally constant thickness into the final configuration shown
herein. As a function of the stamping process, the cylinder end
portion is rolled inward so that an annular end face 261 is formed
with an outer edge 26K being imbued with a radiused surface of
curvature. This allows a surface coating to be formed on the
radiused surface 26K such that the coating is thicker at the
junction between the radiused surface and the outer cylindrical
wall surface of the armature 26C. By having a thicker coating at
this junction, the contact between the end faces of the pole piece
26A and the armature 26C is believed to be in substantially even
contact with each other. It should be noted that the respective
thickness of the end face 26I and the sidewall 26F of the stamped
armature are generally the same. Alternatively, the armature 26C
can be formed by deep drawing a generally flat workpiece through a
suitable die.
[0036] Although both embodiments illustrate an armature 26C of
about the same length, other lengths (e.g., shorter or longer) can
be provided by implementing a different length elongated member 26D
and corresponding polymeric housing 10 in the embodiment of FIG. 1A
or a different length stamped armature 26C and corresponding
polymeric housing 10 in the embodiment of FIG. 2A.
[0037] According to the preferred embodiments, the magnetic flux
generated by the electromagnetic coil 48 flows in a circuit that
includes the pole piece 26A, the armature assembly 26B, the coil
housing 44, and the flux washer 50. The magnetic flux moves along
the coil housing 44 to the base of the coil housing 44, through the
polymeric housing 10 across a radial (relative to axis A-A) or
parasitic airgap to the armature 26C, and across an axial (relative
to axis A-A) or working air gap towards the pole piece 26A, thereby
lifting the armature 26C and closure member 26E off the seat 24A.
As can further be seen in FIGS. 1A or 2A, the thickness of the
cross-section of the impact surface of pole piece 26A is greater
than the thickness of the cross-section of the impact surface of
the armature 26C. The smaller cross-sectional area allows the
armature 26C to be lighter, and at the same time, causes the
magnetic flux saturation point to be formed near the working air
gap between the pole piece 26A and the armature 26C, rather than
within the pole piece passage 26A1. Furthermore, since the armature
26C is partly within the interior of the electromagnetic coil 48,
the magnetic flux is believed to be denser, leading to a more
efficient electromagnetic coil 48. In the embodiment of FIG. 1A,
the ferro-magnetic closure member 26E is magnetically decoupled
from the armature 26C via the non-magnetic elongated member 26D,
which reduces flux leakage of the magnetic circuit, thereby
improving the efficiency of the electromagnetic coil 48.
[0038] In the preferred embodiments, the fuel injector 100 or 200
can be assembled as follows. A polymeric fuel injector body 10 with
an insert-molded solenoid coil assembly 38 is provided, as shown in
Figure IB. The metering assembly 24 is fitted onto the rim portion
28 of the outlet 14 of the polymeric housing 10 and these
components are then bonded to each other by a suitable bonding
technique such as, for example, UV light activated adhesive,
thermal bonding, or laser welding to form a hermetic seal HW.
Details of the techniques to form the hermetic seal HW via adhesive
bonding or laser bonding are also disclosed in related U.S. patent
application Ser. No. 11/014,693, entitled "Method of Polymeric
Bonding A Polymeric Fuel Component to Another Polymeric Fuel
Component," filed on the same date as this application, which
application is incorporated herein by reference in its entirety
into this application.
[0039] The armature assembly 26B is inserted into the polymeric
bore 10A for contiguous engagement with the metering assembly 24,
which form a valve assembly that regulates flow of fuel from the
fuel injector 100 or 200. The pole piece 26A is press-fitted to a
predetermined location within the polymeric bore 10A so that a lift
distance (i.e., the distance the annature assembly 26B travels to
close a working air gap with the pole piece 26A) of the armature
assembly 26B is defined by this predetermined location. The
resilient element 27 is inserted into the pole piece passage 26A1
so that one end contiguously engages the closure assembly. The
filter assembly 52 is press-fitted into the pole piece passage 26A1
so that a distal end of the filter assembly 52 preloads the
resilient element 27 against the armature assembly 26B to provide
for the closure assembly 26. The external seals, preferably Viton
type O-rings, are installed on recessed portions proximate the
inlet 12 and outlet 14 of the fuel injector 100 or 200. At this
point, the fuel injector 100 or 200 is ready to be calibrated
before being tested. The calibration can involve modifying the
preload force of the resilient element 27 such as, for example, by
repositioning the adjusting tube/filter assembly 52 along axis A-A
while flowing fuel through the fuel injector 100 or 200 to achieve
a desired opening time for the closure member 26E. Subsequently,
the fuel injector 100 or 200 can be tested (e.g., flow or leak
testing) prior to being shipped to customers.
[0040] In operation, the electromagnetic coil 48 is energized,
thereby generating magnetic flux in the magnetic circuit. The
magnetic flux moves armature assembly 26B (along the axis A-A,
according to a preferred embodiment) towards the pole piece 26A to
close the working air gap. This movement of the armature assembly
26B separates the closure member 26E from the seat 24A and allows
fuel to flow from the fuel rail (not shown), through the polymeric
inlet bore passage 16, the pole piece passage 26A1, the
through-bore 26G of the armature 26C, the apertures 26F to between
the seat 24A and the closure member 26E, through the seat orifice
24H, and finally through the metering disc 24I into the internal
combustion engine (not shown). When the electromagnetic coil 48 is
de-energized, the armature assembly 26B is moved by the bias force
of the resilient member 27 to contiguously engage the closure
member 26E with the seat 24A, and thereby prevent fuel flow through
the injector 100 or 200.
[0041] Details of the preferred embodiments are also described in
the following related applications: (1) "Polymeric Bodied Fuel
Injector," Ser. No. 11/014,694; (2) "Method of Polymeric Bonding
Fuel System Components," Ser. No. 11/014,693; (3) "Polymeric Bodied
Fuel Injector With A Valve Seat And Elastomeric Seal Molded To A
Polymeric Support Member" Ser. No. 11/014,692; (4) "Fuel Injector
With A Metering Assembly Having At Least One Annular Ridge
Extension Between A Valve Seat and A Polymeric Valve Body ," Ser.
No. 11/014,699; (5) "Fuel Injector With An Armature Assembly Having
A Cup-Type Armature And A Metering Assembly Having A Seat And
Polymeric Support Member," Ser. No. 11/014,698; (6) "Fuel Injector
With A Metering Assembly Having A Seat Secured To Polymeric Support
Member Having A Surface Surrounding A Rim Of A Polymeric Housing
And A Guide Member Disposed In The Polymeric Support Member," Ser.
No. 11/014,697; (7) "Fuel Injector With A Metering Assembly Having
A Polymeric Support Member Which Has An External Surface Secured To
A Bore Of A Polymeric Housing And A Guide Member That Is Disposed
In The Polymeric Support Member," Ser. No. 11/014,696; (8) "Fuel
Injector With A Metering Assembly With A Polymeric Support Member
And An Orifice Disk Positioned A Terminal End Of The Polymeric
housing," Ser. No. 11/014,695; and (9) "Method of Manufacturing
Polymeric Fuel Injectors," Ser. No. 11/015,032, which are
incorporated herein by reference in their entireties into this
application.
[0042] While the present invention has been disclosed with
reference to certain embodiments, numerous modifications,
alterations and changes to the described embodiments are possible
without departing from the sphere and scope of the present
invention, as defined in the appended claims. Accordingly, it is
intended that the present invention not be limited to the described
embodiments, but that it has the full scope defined by the language
of the following claims, and equivalents thereof.
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