Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to fuel metering and
distribution, and more particularly to apparatus for intrv-
ducing and distributing liquid fuel into a rapidly moving
air stream in the formation of a combustible air-liquid fuel
- mixture.
The present application relates to subject matter
in U.S. Patent No. 3,965,221, granted June 22, 1976.
- U.S. Patent 3,778,038, granted December 11, 1973,
explains a method and apparatus for producing a uniform
combustible mixture of air and minute liquid fuel droplets
for dilivery to the intake manifold of an engine. The
apparatus includes an intake air zone connected to a variable
area throat zone for constricting the flow of air to increase
its velocity to sonic. Liquid fuel is introduced into the
air stream at or before the throat zone to minutely divide
- and uniformly entrain fuel as droplets in the air flowing
through the throat zone. Walls downstream of the throat
7one are arranged to provide a gradually increasing cross-
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`- sectional area for efficiently converting a substantial
20- portion of the kinetic energy of the high velocity air and ~ ~ -
fuel to static pressure. Such conversion enables the main-
` tenance of sonic velocity air through the throat zone over
~' substantially the entire operating range of the engine to
- which the air-liquid fuel ~ixture is supplied.
. It is important to meter the proper quantity of
~ fuel into the high velocity air stream in order to obtain a
~~ combustible mixture having a substantially constant air-to-
fuel ratio. It is equally important that the fuel so intro-
duced be properly
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distributed since uniform distribution plays a major role in
consistently ob-taining a substantially constant air-to-
fuel ratio. Air and fuel introduction rates often vary by
a factor of 40 when comparing idling conditions wi-th those
encountered during rapid acceleration. Such conditions
demand fuel metering and distribution apparatus having
special characteristics such as the avoidance of excessive
quantities of liquid fuel at the point where the fuel
enters the air stream or at other locations. Uniform fuel
distribution and properly metered quantities of ~uel are
of paramount importance in the production of combustible
--~ mixtures.
According to the present invention there is
provided a fuel bar for introducing and distributing pre-
determined amounts of liquid fuel into a rapidly moving
air stream including fuel discharge structure having a
~, fuel opening arranged perpendicular to the path of air
flow. A rod is slidably received within the fuel opening
perpendicularly extending across the path of air flow,
and at least two pairs of spaced apart tapered slots axe
provided in the rod for varying the cross-sectional area
~- of the fuel flow through the opening as the rod is moved
relative thereto. Each tapered slot,of each pair has a
decreasing cross-sectional area in a direction outwardly ''
away from the opening and each slo-t extends along the
length o~ the rod for dist,ributing the fuel along the rod ,
where it is stripped away by the ra~idly moving air stream.
' 'At least the first pair of the slots is located in the up-
., stream half of the rod.
In a specific embodiment of the invention, the
' rod has a substantially circular cross-section and the
diameter thereof is within the range of one-eighth and
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three-eighths inches. The rod slides relative to the
fuel opening between an idling position and a wide open
throttle position. The depth of each slot at the fuel
opening ranges from 0.001 to 0.010 inches at the idling
position to about 0.090 to 0.100 inches at the wide open
throttle position.
Brlef Descri~tion o~ the_Drawings
Novel features and aclvantages of the present
invention in addition to those mentioned above will become
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apparent to those skilled in the art from a reading of
the following detailed description in conjunction with the
accompanying drawings wherein similar reference characters
refer to similar parts and in which:
Figure 1 is a top plan view of a fluid flow
device having fuel metering and distribution apparatus,
according to the present invention;
Figure 2 is a sectional view taken along line
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2-2 of Figure l;
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Figure 3 is a sectional view taken along line
`j~ 20 3-3 of Figure l;
Figure 4 is a side elevational view of the fuel
metering and distribu-tion rod shown in Figures 1-3;
Figure 5 is a top plan view of the rod shown in
. . .
Figure 4;
~- Figure 6 is an end elevational view of the rod
shown in Figures 4 and 5;
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Figure 7 is a sectional view taken along line
i~ 7-7 of Figure 6;
: Figure 8 is a top plan view of another fuel !~
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metering and distribution xod, according to the present
invention; and
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Figure 9 is an end elevational view of the rod shown in
Figure 8.
Detailed Description of the Invention
Referring in more particularity to the ~rawings, Figures
1-3 illustrate a fluid flow device 10 for mixing and modulating
liquid fuel and air in the production o~ a combustible air-liquid
fuel mixture haviny a substantially constant air-to-fuel ratio.
Generally, the device 10 comprises an elongated housing with a
central flow passageway therein. The passageway is defined by a
` 10 pair of opposite stationary large jaws 12, 14 and a pair of op-
posite small members in the form of slabs 16, 18. As explained
`~ more fully below, slab 18 moves toward and away from stationary
~; slab 16 to vary the mass flow of air passing through the passage-
way. Specifically, the passageway includes a gradually converging
- 15 air entrance zone 20, a variable area throat zone 22, and a grad-
~ ually diverging downstream zone 24. The stationary jaws 12, 14
- together with slab 16 and housing end wall 26 are secured to a
-` rectangular base plate 28 having openings 30 therein for securing
- the device 10 to the intake manifold (not shown) of an internal
combustion engine.
The inside walls of the opposite stationary large jaws
are shaped to define a venturi cross section with the small slabs
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~; 16, 18 and this venturi cross section includes the air entrance
~; zone 20, the throat zone 22, and the gradually diverging downstream
zone 24. Atmospheric air enters the mixing and modulating device
10 at the air entrance zone 20, and the air is accelerated to sonic
velocity at the throat zone 22. Liquid fuel is introduced into
the high velocity air stream at a fuel opening 34 upstream from
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the throat 22. The fuel opening 34 is located in the stationary
slab 16, and a fuel source (not shown) is connected to the openingO
A fuel metering and distribution rod 36 mounted for mo~ement with
;~ the movable slab 18 is received within the fuel opening 34 to vary
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the rate of fuel delivered into the high velocity air stream. The
rod has a pair of spaced apart tapered slots 38, 40 ~or varying
the cross-sectional area of fuel flow through the opening 34 as
the rod is moved relative thereto, as explained more fully below.
The sonic velocity air-liquid fuel mixture passes from
the throat zone 22 into the gradually diverging downstream zone 24
where the kinetic energy of the high velocity air and fuel is ef-
`-~ ficiently converted static pressure. Such conversion enables the ;
- maintenance of sonic velocity air and fuel flow through the throat
- 10 zone 22 over substantially the entire operating rangeof the engine. ; -
Thus, sonic velocity is achieved at the throat zone even at very
low manifold vacuum levels.
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- ~he mass flow of air passing throuyh the device 10 is
primarily governed by the position of the movable slab 18 relative
to the stationary slab 16. rlovement of the slab 18 varies the
- cross-sectional area of the throat zone, and under sonic conditions ;
such ~ariation is accompanied by an e~ual variation in the mass
flow of air. However, such equal mass flow of air is only achieved
when the atmospheric conditions remain constant, as explained more
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~ bar 41 extending through an opening in the end plate
26 is secured to the outside surface of the movable slab 18. This
- bar is under the control of a throttle linkage (not shown), and the
cross-sectional area o~ the throat zone is varied by moving the
slab 18 in direct response to operating demands imposed upon the
engine to which the device 10 is attached. Such demands are Lm-
posed upon the throttle linkage which in turn causes the bar 41 to
move slab 18 to vary the throat zone area. Since the fuel meter
ing and distribution rod 36 is connected for movement with the
slab 18 it is also under the direct control of the throttle link-
age. The relationship between the metering rod 36 and the fuel
j opening 34 is such that incremental changes of the throat area are
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accompanied by proportional changes in the free cross-sectional
area between the slotted rod and the fuel opening. Hence, under
sonic air flow and constant atmospheric conditions, when the area
oE the throat zone is varied such variation is accompanied by a
directly proportional variation in the fuel delivered into the
high velocity air stream. The air-to-fuel ratio of the mixture
produced remains constant even though the demands of the engine
change.
It is significant that the inside walls of the slabs
16, 18 are parallel to one another at least from the throat zone
22 to somewhat above the elevation of the fuel opening 34. By
providing such a relationship, the ratio of the cross-sectional
area at the fuel opening 34 relative to the area of the throat
zone 22 remains constant. Changes in the area of the throat zone
15 are accompanied by linearly related changes in the area of the air
entrance zone 20 at the fuel opening 34. With such a constant
area ratio, the pressure at the point of introduction of fuel into
the air entrance zone 20 bears a predictable relationship to the
pressure at the throat. As explained above, under sonic condi-
tions, the pressure at the throat 22 is always approximately 53%of atmospheric pressure. Since the ratio of the area at the point
of fuel introduction relative to the area at the throat zone 22
remains constant, the pressure at the fuel introduction point 34
in the air entrance zone 20 is always the same percentage of
atmospheric pressure. Thus, changes in atmospheric pressure are
` automatically reflected in the pressure at the fuel introduction
` location 34.
It is desirable to produce a vacuum signal at the fuel
introduction point of about 1 inch Hg., and the point of fuel
introduction is therefore located away from the throat at a posi-
tion in the air entrance zone where about 1 inch Hg. vacuum exists
during sonic flow at the throat. Without a constant area ratio
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between the throat and the fuel introduction point, the vacuum
signal at the fuel point would not vary directly with the throat
opening and the only location of unvarying vacuum would be at the
throat. Difficulty in precise location of the throat could result
in a varying signal at this location.
ThP fuel metering and distribution rod 36 functions to
introduce and distribute predetermined amounts of liquid fuel into
the rapidly moving air stream passing through the fluid flow de-
- vice 10. As noted above, the rod is slidably receivad within the
fuel opening 34 and it transversely extends across the path of air
` flow. The pair of spaced apart tapered slots 38, 40 provide chan-
nels along which the liquid fuel flows when such fuel is introduced
into the air stream. Preferably the tapered slots 38, 40 are
spaced apart approximately 120, as shown best in ~igure 6. How-
ever, spacing ranging from 90 to 120 may also be utilized. The
width of each slot is approximately 0.030 inches, and the taper of
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each slot is such that proper amounts of liquid fuel are intro-
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duced into th~ air stream as the mass thereof varies. In this
regard the rod slides relative to the ~uel opening between an
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idling position and a wide open throttle position. The depth of
each slot at the fuel opening ranges from 0.001 to 0.010 inches
~` at the idling position to about 0.090 to 0.100 inches at the wide
open throttle position. Finally, the rod has a substantially
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circular cross section, the diameter of which i5 in the range of
one-eighth and three- eighths inches, preferably one-fourth
inches.
i The tapered slots 38, 40 are located in the upstream
half of the rod 36 and serve to distribute the fuel along the rod
where it is stripped away by the rapidly moving stream. Additional
tapered slots 42, 44 may be provided in the downstream half of the
rod 36, as shown best in Figure 4. The slots 42, 44 are tapered
in the same directions as the slots 38, 40 but extend only about
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half way along the rod. The slots 42, 44 enable additional liquid
fuel to be introduced into the air stream at the wide open throttle
position of the rod and those throttle positions which are close to
wide open. Such additional fuel introduction provides an air-~uel
mixture for increased power purposes.
Figures 8 and 9 illustrate another fuel metering and
distribution rod 46 that functions to introduce and distribute
predetermined amounts of li~uid fuel into a rapidly moving air
~tream. The rod 46 has four spaced apart tapered slots 48 in the
upstream half thereof and each slot is separated from an adjacent
one by approximately 40, as shown best in Figure 9. The width of
the slots 48 of rod 46 are somewhat smaller than the width of the -
slots of the rod 36. Also, the taper may be more yradual in the
case of the slots 48. Otherwise, the fuel metering and distribu-
- 15 tion rod 46 functions in the same manner as the fuel rod 36. More-
over, additional slots may be provided in the downstream half of
rod 46, if desired.
In operation, the pressure of the high velocity air
stream flowing through the passageway of the device 10 is sensed
,
~ 20 at the fuel opening 34 where it bears a predictable relationship
- to atmospheric pressure. The rate of fuel delivered into the air
^- stream is adjusted in response to changes in the air pressure
sensed so that the air-to-fuel ratio of the air-liquid fuel mix-
ture is maintained substantially constant. Adjustment of the rate
of fuel delivered into the air stream is accomplished by the
chan~e in pressure differential across the valve that comprises
~ the metering and distribution rod 36 and the fuel opening 34. For
;; reasons noted above, the pressure of the air stream at the fuel
- opening 34 changes in proportion to atmospheric pressure varia-
tions, and the pressure change at the fuel opening results in a
" change in the pressure differential across the valve. The rate of
fuel delivered into the air stxeam is thereby adjusted in direct
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~ response to changes in atmospheric pressure.
- During the relatively brief subsonic mode of operation
when the manifold vacuum levels are quite low, the fluid flow
device functions as a metering venturi to introduce varying
quantities of liquid fuel into the varying velocity air stream.
Due to the efficient conversion of the energy of the high velocity
air and fuel to static pressure in the diffuser, sonic air flow at
the throat zone 22 is maintained over just about the entire
operating range of the engine. However, at very low manifold
vacuum level~s of below 5 inches Hg. vacuum, for example, the air
flow at the throat zone 22 may drop below sonic and the reduced ;
velocity operates to suck less fuel into the passageway. During
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` the subsonic mode the vacuum signal at the fuel opening 34 varies
as the air velocity squared.
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