Note: Descriptions are shown in the official language in which they were submitted.
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Description
Electromagnetic Fuel Injector
with Improved Discharge Structure
Technical Field
The invention relates to fuel injectors and more
particularly to electromagnetically operated fuel in-
section valve for internal combustion engines. More
particularly still, the invention relates to an imp
provement in the structure of the discharge region of
such fuel injection valves.
Background Art
In the quest to improve fuel economy, increase
engine operating performance and/or to reduce various
emissions from the engine, there has been considerable
development of fuel injectors, particularly electron
magnetically operated injectors for spark ignited
engines. One consideration in the design of such in-
vectors is the pattern of the fuel issuing from the
discharge opening of the injector. These patterns
often must differ as a function of the location of
the injector on and in the engine. In many instances,
a relatively broad-angle hollow, conical fuel spray
is desired. In yet other instances, the desired fuel
spray pattern comprises a relatively narrow-angle
solid cone. In yet other applications, the desired
fuel injection pattern is a serial string or chain of
droplets. Generally speaking, the provision of these
widely different spray patterns has required relatively
significant changes in the structural design of the
discharge region of the injector. Such changes in de-
sign are typically expensive to implement.
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Moreover, in providing particular configurations
to the fuel spray pattern discharged by the injector,
it is often common to provide for swirling the fuel
prior to its final exit from the injector to enhance
atomization. The structure for creating that swirling
effect may be located upstream or downstream of the
valve and valve seat. Further still, a metering oft-
flee may be provided downstream of the valve for con-
scantly metering the quantity of fuel discharged while
the valve is open. The inclusion or non-inclusion of
a metering orifice in addition to the valve, the post-
toning of that orifice, the inclusion or non-inclusion
of swirling means and the positioning of such swirling
means comprise variables which have existed in certain
different combinations, as illustrated by US. Patents
2,974,881 to Guard, 4,030,668 to Corey, 4/033r513 to
Long, 4,060,199 to Brute et at, 4,116,389 to Fort et
at and assigned to the assignee of the present invent
lion, 4,186,883 to Rolling and assigned to the assignee
of the present invention, 4,192,466 to Tunis et at,
4,218,021 to Palm and ~,230,273 to Clayton et at.
While the injectors of each of the aforementioned
patents may be well suited to accomplishing certain
design criteria, they do not readily suit the need
for a relatively economical electromagnetically act
tufted fuel injector which wraps but a minimum of fuel
following valve closure and which. may be relatively
simply and economically modified to provide a wide
range of fuse]. spray patterns.
Accordingly, it is a principal object of the
present invention to provide an improved electromag~
nautical actuated fuel injector in which the con-
struction of the discharge region minimizes the trap-
ping of fuel and provides for the relatively simple
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and economical adoption of a variety of widely differ-
in fuel spray patterns.
In accordance with the present invention, there
is provided an electromagnetically actuated fuel in-
Hector which includes a housing having a flow passagetherethrough including an inlet region and a discharge
region. A valve seat and a valve are positioned with-
in the flow passage. An armature is operatively con-
netted to the valve and an electromagnetic actuator is
controllable to move the armature and thus the valve,
between open and closed positions relative to the
valve spat Fuel under pressure passes through the
valve when it is opened and subsequently passes through
the discharge region downstream thereof where it is
discharged from the housing. The discharge region of
the injector is of improved construction and includes
a central flow axis and, sequentially in the downstream
direction, a simple metering orifice symmetrical with
the axis, and flow patterning structure including a dip
Jo verging flow director for directing the flow of fuel issuing from the metering orifice radially outward
relative to the axis to an annular region about the
axis and converging flow director for directing the
fuel radially inward relative to the axis from a post-
US lion radially outward thereof for direct transparent discharge thereafter from the injector. As used above
and subsequently herein, "transparent" means without
significant subsequent pressure drop. A discrete exit
nozzle may be shaped to effect the requisite flow con-
virgins, and the angle of that convergence affects the geometry of the final spray pattern.
A third flow-directing element may conveniently
be provided intermediate the other two flow directors
to further control development of the issuing fuel
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pattern, as for instance to enhance atomization of the
fuel. That element may be a cylindrical disc member
having a plurality of channels in the circumference
thereof, typically for imparting a swirl to the fuel.
By preselecting the angle at which the channels in the
swirl disc are skewed to the axis, it is possible to
obtain respective ones of a variety of fuel spray pat-
terns ranging from a wide angle hollow cone for an
acute angle of tangentiality to a string of fuel drop-
lets substantially along the axis when the swirl chant
nets are substantially parallel the axis and impart no
swirl. The upper end of the swirl disc may be conic
gaily tapered to provide diverging flow director, and
the other end of the disc may be similarly tapered to
facilitate manufacture and assembly.
Brief Description of the Drawings
Fig. 1 it an elevation Al sectional view of an
improved electromagnetically actuated fuel injector
in accordance with the invention;
Fig. 2 is an enlarged partial view of Fig. 1 show-
in the discharge region of the injector in greater
detail and with a particular structural geometry which
provides a particular spray pattern;
Fig. 3 is a sectional view of the swirl plug taken
US along line 3 3 of Fig. 2;
Fig. is a sectional view similar to Fig. in
which certain changes in structural geometry produce
a chanted spray pattern; and
Fig. 5 is a view similar to Fig. 4 in which the
structural geometry is changed still further to create
an extreme flow pattern.
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Best Mode for Carrying Out the Invention
Referring to Fig. 1, there is illustrated an eye-
rational sectional view of an electromagnetically act
tufted fuel injector 10 in accordance with the present
invention. A generally elongated tubular housing is
provided by a tubular housing member 20 of non-
magnetic material, a valve container ring 22 and a
valve body assembly comprised of a valve body 23, a
swirl disc 24 and an exit nozzle 25. The housing
member 20 comprises the upper portion of the injector
housing, with the lower remaining portion being formed
by valve container ring 22 and the valve body assembly.
The housing member 2Q includes a lower portion of rota-
lively large diameter and an upper portion of relative-
lye smaller diameter. The lower end of housing member
20 is deformed inwardly to provide an upwardly facing
flange which enrages a downwardly facing shoulder on
an annular rim 26 of the valve container ring 22 to
axially retain the container ring.
The diameter of the annular ring 26 of ring 22
is sized for close-fitting insertion into the housing
member 20. A first conically-inwardly tapered section
of container ring 22 depends from ring 26, followed by
a second lower substantially cylindrical section.
The valve body 23 is a generally tubular member
which is threadedly inserted into and retained within
the o'er cylindrical section of the valve container
ring 22. The valve body 23 includes an upper portion
which extends within the conically-walled section of
the valve container ring 22 and spaced relation there-
with to form an annular fuel chamber 28 there between.
One or more ports 29 extend through the conical wall
of valve container ring 22 to provide an inlet opening
to the fuel chamber 28 of injector 10 from a source of
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pressurized fuel 'not shown) such as gasoline.
The upper portion of the valve body 23 includes a
machined central opening which is cylindrical at its
upper end 27 and is tapered conically inward there-
below to form an annular valve-seating surface 30 and,
further below, includes a cylindrical metering orifice
32 of relatively small diameter. This central opening
in valve body 23 extends through the length thereof
and, below metering orifice 32, opens to a larger
diameter in which a disc 24 is installed for imparting
a directional component, typically tangential to pro-
dupe a swirl, to the flow of fluid there through. The
swirl disc 24 may be press-fitted into the central
opening or may be retained therein by a tubular exit
nozzle 25 press-fitted into the opening. The exit
nozzle 25 provides the final discharge outlet from
the injector for fuel being injected into the engine.
This region downstream from the valve seat 30 to the
discharge opening of the exit nozzle 25 is referred
to herein as the discharge region and will be disk
cussed hereinafter in greater detail.
Fuel from reservoir 28 is admitted to the bore 27
within valve body 23 by means of one, or preferably a
plurality of, ports 34 extending tangentially or prey-
I drably radially through the valve body 23 above the valve seat 30. Fuel may also pass from reservoir 28
into the upper end 27 of the central bore over the
upper end of the valve body 23.
A ball valve element 36 is positioned within the
uppermost part 27 of the central bore in valve body 23
and cooperates with the valve seating surface 30 to
prevent or allow the flow of fuel from reservoir 28
and ports I for discharge to the engine via the disk
charge region downstream thereof.
lo
The ball valve 36 is attached to an armature 40
of magnetic material. The armature 40 is part ox an
electromagnetic motor or solenoid 42 housed in housing
member 20. The solenoid 42 selectively controls the
S axial positioning ox armature 40, and thus the ball
valve 36, to open or to allow the closing of the valve,
thereby allowing or preventing the discharge of fuel
from injector 10 into the engine.
The solenoid 42 includes a wire coil 44 disposed
on bobbin 46 which is disposed between the radially
inner and outer sections AYE and 48B respectively of
an annular magnetic frame. The inner magnetic frame
section AYE includes a cylindrical, fluid passing bore
51 extending coccal there through into the top end
of which is threadedly inserted a tubular spring
adjuster 50 having a fluid passing bore 52 extending
coccal there through. A helical compression spring
54 positioned within the central bore of inner mug-
netic frame AYE applies a downward, or closing,
biasing force to the upper surface of armature 40 and
thus also to the ball valve 36.
The upper portion of housing member 20 is, in
the illustrated embodiment, open at its upper end to
provide a return outlet opening 60 from which fuel may
be returned to a reservoir and pump, typically via a
pressure regulator (not shown). Fuel admitted to the
reservoir 28 via inlet opening 29 is able to continue
ouzel pass upwardly through and around the armature 40
via various openings 68 extending axially there through,
and thence through the central bore 51 and out through
the return outlet opening 60. Although this flow path
is not necessarily present in all injectors, in most
instances the armature 40 and ball valve 36 will be
continuously immersed in fuel. The other flow path
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in the system is, of course, the valved flow path from
reservoir 28 which extends past the valve seat 30, and
through the discharge region of the injector for in-
section to the engine.
The coil 44 is attached to a pair of terminals 56
(only one being shown). application and removal of an
appropriate electrical potential to the terminals 56
operates in a known manner to actuate the armature 40
and ball valve 36 and thus open or close the valve.
In accordance with the invention, the discharge
region of injector 10, and specifically that region
of the valved flow path downstream of valve seat 30
is of a construction which minimizes trapped fuel upon
valve closing and is of a relatively simple but versa-
tile construction which minimizes the cost and come
plexity of affording a relatively wide range of fuel
spray patterns by the substitution of but a few easily
manufactured components.
Referring to Fig. 2 for a more detailed consider-
lion of the discharge region of the valve flow path,
it will be noted that the metering orifice 32 is a
single, small diameter opening concentric with the
central flow axis 70 of the discharge region. Meter-
in orifice 32 is positioned in close proximity with
the region of contact of ball valve 36 with seating
surface 30 so as to minimize the volume there between
in which fuel may be trapped following closure of the
valve. In accordance with the invention, the area of
metering orifice 32 normal to the direction of flow
thereat will be equal to, or preferably less than,
the smallest cumulative area of the flow path normal
to the direction of flow anywhere downstream thereof
in the discharge region. Such dimensioning enables
the entering orifice 32 to be the final metering
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g
element. It will be understood that additional meter-
in may occur upstream of metering orifice 32, as for
instance at the valve and valve seat region.
Downstream of the metering orifice 32, the central
opening in valve body 23 gradually increases in dime-
ton along a truncated conical zone 72 of the opening
in which divergence of the flow occurs. The flow dip
verging zone 72 is followed by a generally cylindrical
section I in which the swirl disc 24 is positioned.
The final downstream section 76 of the opening in valve
body 23 is elongated and cylindrical, and receives exit
nozzle 25 which includes a flow-converging surface 87.
In accordance with the invention, the flow of fuel
issuing from metering orifice 32 is first caused to
radially diverge within diverging zone 72 and is sub-
sequently caused to radially converge in the converging
region 87 of exit nozzle 25 for discharge from the in-
Hector. The axially opposite ends of swirl disc 24
are each provided with integrally formed conical ox-
tensions 78 such that the disc member 24 is symmetric
eel about a plane transverse to the central flow axis
70 and is thus capable of installation in section 74
of the bore in either orientation, thereby facilitating
assembly.
More particularly, the conical extension 78 ox-
tending in the upstream direction aids in diverging
the fuel flow as it issues from metering orifice 32,
as represented by flow direction arrows 80. This flow
diverges to an annular region having its outer diameter
defined by the axial section 74 of the central bore.
The cross-sectional area of flow path 80 normal to the
direction of flow is somewhat greater than at metering
orifice 32 and remains substantially constant through-
out the diverging zone 72 of the bore.
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The disc 24 is positioned in the axial section
74 of the central bore and substantially occludes the
cross section of that bore except for one, or prefer-
ably a plurality, of grooves or channels 85 extending
generally axially along the periphery of the plug in
that region. Grooves 85 provide liquid communication
between the diverging region 72 of the bore and the
converging region 87 there below at the upper end of
the exit nozzle 25. The grooves 85 may, in an extreme
instance depicted in Fig. 5, be formed to extend penal-
lot to the central flow axis 70. However, it will be
desirable in the instance of most different fuel spray
patterns to impart a swirl to the fuel as it passes
through this region 74 and accordingly, the longitude-
net axes of the respective grooves 85 are skewed rota-
live to the central flow axis 70 to provide a generally
tangential component to the flow. The cumulative cross
sectional area of the grooves 85 is preferably as great
as that existing in the divergent zone 72 so the flow
is not unduly restricted. More specifically, in the
illustrated embodiment that area is substantially the
same as that in the diverging zone 72.
Fuel issuing from disc grooves 85 is then con-
verged, placing some portion of the fluid in shear
and thereby enhancing atomization of the fuel. This
convergence of the fuel stream is obtained by a down-
warmly and inwardly beveled converging surface 87 near
the upper end of the exit nozzle 25. The converging
surface I is of truncated conical form, its larger
diameter base being of substantially the same diameter
as an being adjacent to the lower end of zone 74, and
its smaller diameter being positioned downstream
thereof and corresponding with the inside diameter of
the remainder of exit nozzle 25. The full or included
so
angle of the converging wall 87 bisected by fledge axis
70 may be in the range of about 15-120, and typically
in the range of 60-80. The diameter of the base of
the conical extension 78 at the underside of swirl
disc 24 is sufficiently small and the included angle
of that cone is sufficiently large that the annular
region of convergent fuel flow defined by it and the
converging surface 87, and represented by flow arrows
89, do not restrict the flow of fuel issuing therefrom.
Similarly, the inner diameter of exit nozzle 25 is
sufficiently large that it does not impede or restrict
the flow of fuel issuing therefrom. Thus it may be
said that the discharge region downstream of metering
orifice 32 is "transparent" to the flow of fuel there-
through. The length of exit flow nozzle 25 will typic
gaily be about 7 millimeters and its inner diameter
will be in the range of 1-4.5 millimeters, depending
upon the fuel spray pattern desired.
In the embodiment illustrated in Figs. l, 2 and
3, the fuel spray pattern 90 issuing from injector lo
is in the general form of a hollow cone having an in-
eluded angle, I, of about 60. For a given set of
flow and pressure conditions at and upstream of the
metering orifice 32, the geometry of the flow pattern-
in structure which provides this pattern includes the diverging cone 78 on swirl disc 24 having an in-
eluded angle of 100, the swirl disc 24 having six
flow grooves or channels 85 each skewed at an angle
of 45 to the central flow axis 70, the flow converge
in surface 87 having an included angle of 60 and the internal diameter of exit nozzle 25 being about
3 millimeters.
Referring to Fig. 4, the geometry of two elements
of the flow-patterning structure of the injector has
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been modified somewhat to provide a significantly
different fuel spray pattern 90' having the form of
a solid cone with an included angle, I, of about 15.
The modified components in this embodiment are design
noted by primed reference numerals and include the swirl channels or grooves 85' in swirl disc 24' being
skewed at an angle of about 10 Jo the central flow
axis 70. Additionally, the included angle defined by
the convergence surface 87' is about 80 and the inner
diameter of exit nozzle 25' is about 1.2 millimeters.
Fig. 5 illustrates an embodiment of yet another
variation in the geometry of the flow-patterning
structure of injector 10, those elements which are
modified being designated by reference numerals bear-
in double-primed superscripts. This embodiment
represents a limit or extreme condition in which the
fuel spray pattern 90i' its in the form of a serial
string of droplets or a suckled "string of pearls",
as may be required for certain engine applications.
This fuel pattern is obtained principally by orient
in the flow channels 85'' in swirl disc 24'' such
that they impart little or no tangential or radial
component to the fuel flowing there through. In this
instance, the axial dimension of the cylindrical port
-lion of disc 24 " may be reduced to a minimum. Three
Reeves 85'' are provided in disc 24''. Additionally,
the included angle of the converging surface 87'' of
exit nozzle 25'' is approximately 80, and the inside
diameter of exit nozzle 25'' is about 1.5 millimeters.
In view of the foregoing description, it will be
appreciated that the structuring of the injector disk
charge region, and particularly the flow-patterning
elements thereof, in accordance with the invention
affords the ability to -fabricate injectors having a
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variety of differing fuel spray patterns with the sub-
stitution of only two components having the requisite
modifications therein. In some instances, it may be
desirable to modify the diameter of metering orifice
32 somewhat, usually to change the rate of fuel in-
section, however, this modification is easily accom~
polished during the machining of that orifice More-
over, the sequence in which the components of the
discharge region of the injector are arranged serves
to minimize the volume of fuel trapped downstream of
the valve seat and facilitates the transparent disk
charge of fuel issuing from the metering orifice.
Although this invention has been shown and de-
scribed with respect to detailed embodiments thereof,
it will be understood by those swilled in the art that
various changes in form and detail thereof may be made
without departing from the spirit and scope of the
claimed invention.
