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Патент USA US3093707

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June 11, 1963
Filed March 3, 1961
4 Sheets-Sheet 1
F IG. 3.
F IG. 2.
June 11, 1963
Filed March 3, 1961
4 Sheets-Sheet 2
June 11, 1953
Filed March 5, 1961
4 Sheets-Sheet 3
June 11, 1963
Filed March 5, 1961
4 Sheets-Sheet 4
Patented June 11, 1963
an arm 13 secured to the other end of the choke shaft 9.
A throttle shaft 14 is journaled vertically in bearing
apertures formed in the body 2, as shown in FIG. 6, to
Wilmar W. Degenhardt, St. Louis, Mo” assignor to‘ ACF
Industries, Incorporated, New York, N.Y., a corpora
tion of New Jersey
support a throttle valve 16 for pivotal movement in the
outlet 6, the shaft v14 being engaged against axial move
ment by means of a plate 17 secured to the body by a
screw 18 and having an end thereof engaged in an annular
Filed Mar. 3, 1961, Ser. No. 93,177
1 Claim. (Q1. 261-41)
groove 19 formed in the shaft. A manually operable
This invention relates to carburetors for internal com
bustion engines.
control arm 21 is secured to one end of the throttle shaft
10 14 to control the proportion and quantity of fuel and air
The present invention contemplates the provision of a
carburetor particularly adapted for use with small in
supplied to the engine. The throttle valve 16 is biased
toward its closed position by means of a helical torsion
spring 22 having one of its ends engaging the body 2
gines and other applications. As the horsepower of these
and its other end engaging the control arm 21, as shown
engines has become greater there has been an increasing 15 in FIG. 6.
demand for greater fuel economy and better control of
The body 2, as illustrated in FIG. 6, is provided with
engine operation, during the range of engine speeds from
a downwardly projectingtubular stem 23 having its lower
idle to full speed.
end internally ‘threaded at 24 for engagement with the
ternal combustion engines, such as outboard marine en
It is therefore an object of this invention to provide
lower externally threaded end 25 of a main fuel nozzle 26.
a novel controllable fuel supply system for a carburetor. 20 The lower end of the nozzle 26 has an enlarged bolt head
It is another object of this invention to provide a novel
27 for engagement by a tool to enable the assembly of
fuel supply system for a carburetor to accurately propor
nozzle 26 within stem 23 so that it extends through a
tion the fuel and air mixture of the carburetor to meet
?tted portion 28 of body 2 into the venturi section 7 of
engine requirements throughout the range of engine
conduit 3. An O-ring '39- forms a ?uid seal between
25 nozzle 26 and body portion 28. The portion of the nozzle
A further object of the invention is to provide a car
buretor embodying an idle fuel system interconnected
with a main fuel system, which is selectively operable re
sponsive to manual operation of a throttle valve.
Another object of the invention is to provide a car 30
buretor adaptable to small engines and which is inexpen
sive in construction and reliable in operation throughout
the speed range of an engine.
The invention embodies other novel features, details
of construction and arrangement of parts which are here
inafter set forth in the speci?cation and claim and illus
trated in the accompanying drawings, forming part there
of, wherein:
FIG. 1 is a top plan view illustrating a carburetor em
bodying features of the invention.
between its threaded end 25 and the ?tted body portion
28 is reduced in diameter to de?ne a fuel Well 29‘ with
the stem 23. A plurality of ports 31 are formed in the
nozzle 26 for the passage of fuel into and out of the lower
end of the well 29‘. An air bleed passage 32 is formed
in the body 2 leading from the carburetor inlet 4 to the
upper end of the well 29.
The upper end of the main fuel nozzle 26 projects up
wardly into the venturi 7 posterior to the throat 8 and
35 is provided with a plurality of fuel ports 33. A fuel
metering ori?ce 34 is formed in the lower end 25 of the
main fuel nozzle 26 to receive the lower end 36 of a
metering tube 37. The upper end of the metering tube
37 is formed with a rounded head 38.
Tube 37 is re
FIG. 2 is an elevation showing one side of the car
buretor of FIG. 1.
FIG. 3 is an elevation showing the opposite side of
siliently supported from head 38 upon a helical compres~
sion spring 39 seated at its lower end in a metal cup 40
press-?tted into a bore 41 formed in body .2. The meter
ing tube 37 extends for axial movement through a bear
the carburetor of FIGS. 1 and 2.
ing portion of cup 40 and a bearing portion 412 of body 2.
The under portion of the body 2 is formed with a
FIGS. 4 and 5 are respectively elevations showing op 45
downwardly projecting annular ?ange 43 having a recess
posite ends of the carburetor of FIGS. 1 through 3.
44 therein to receive the rim 42 of a cup-shaped fuel
FIG. 6 is a longitudinal section ‘taken along the line
6—~6 of FIG. 1.
bowl 46. The bottom '45 of the bowl 46 has an aper
ture 47 to receive the nozzle structure 26. During the
FIG. 7 is a transverse section taken along the line
50_ assembly of the carburetor, the nozzle v26 is inserted
7-7 of FIG. 2.
through bowl aperture 47 and into the well portion 29
FIG. 8 is a fragmentary section showing the throttle
valve in closed position.
of stem 23, with a gasket washer 48 between the bottom
45 of bowl 496 and bolt head v2'7. By screwing the
FIG. 9 is a fragmentary section illustrating the meter
threaded end ‘25 of the nozzle into the threaded end 24
ing rod as positioned within the main fuel nozzle to con
55 of stem 23, head 27 ?rst forces the bowl rim against a
trol the ?ow of fuel therethrough.
gasket 49 in the recess 44, and then forces the bowl bot
Referring now to the drawing for a better understand
tom 45 against the stem 23 with gasket 48' making a ?uid
ing of the invention, the carburetor is shown as compris
seal between head 27 and the bowl 46.
ing a body 2 having a horizontal mixture conduit 3 (FIG.
A hollow ring-shaped float 51 is mounted on a pin 5-2
6) provided with an air inlet 4, an outlet 6, and a venturi
60 (FIG. 7) for pivotal movement within the fuel bowl to
7 having a throat 8. A flange 1 is provided on the outlet
actuate a needle valve 53 to control the flow of fuel
end of the body 2 for attachment to an inlet manifold 5
through an inlet 54 and valve port 56 into the bowl. The
of an engine E.
A choke valve shaft 9‘ is jounaled horizontally in hear
?oat and valve are adapted to coact to maintain a sub
ing apertures formed in the body 2 to support a choke 65 stantially constant fuel level within the bowl. An air
vent 75 leads through the body 2 to the bowl. Fuel is
valve 11 for pivotal movement within the air inlet 4.
supplied from a tank T (FIG. 1) through a conduit 57
The choke valve 11 is normally maintained in its full
and a fuel pump P to the fuel inlet 54‘. Fuel passes from
open position, as indicated in FIG. 6, by means of a tor
the bowl 46 through ports 55 of stem 23 into a chamber
sion spring'12 (FIGS. 3 and 5) having one end thereof
66 in the nozzle end 25 below the ori?ce 34. Fuel flows
secured to the shaft 9‘ and its other end secured to the 70 through metering ori?ce 34 and ori?ces 31 to a level in
body 2. The choke valve 11 is adapted to be pivoted
well 29 and nozzle 26 equal to that maintained by ?oat
to its closed or choke position by manual movement of
51 in bowl 46.
In accordance with the invention, the idle fuel system
In the operation of a boat equipped with two 50 or 60
of the carburetor is designed as an interconnected system
horsepower outboard engines, it will be appreciated that
such a saving in fuel is of major importance, as it de
with the primary fuel system through nozzle 26. The
creases the cost of operation and permits an increase in
metering tube 37 is formed with a hollow central channel
the range a boat may travel when supplied with a pre
59 and with closed ends at 36 and 38. The hollow chan
determined quantity of fuel.
nel 59 extends from a restricted aperture 62 at the lower
end of tube 37 which is adapted to be positioned below
During idle operation of the engine E, the throttle
valve 16 is in its closed position and fuel is supplied to
the fuel level within bowl 26 at all times. At the upper
the mixture conduit through the idle system. Under
end of the tube 37, aperture 65 connects the inner
such conditions there is a flow of su?icient air for idling
channel 59 with the chamber 41 in the carburetor body
through apertures 64 of the throttle plate '16. In the
2. In an intermediate portion of tube 37, four apertures
58 are formed through the tube wall connecting the inner
carburetor during idle, the region of lowest air pressure
channel 59 thereof with the air flow through the venturi
is immediately posterior to the closed throttle valve 16
section 7. As shown speci?cally in FIG. 7, the body
and in the carburetor outlet 6. This point of 10W pres
chamber 41 is connected by a passage 61 to a bore 70 15 sure is one which is reflected back through the idle feed
and a second body cavity 72. An idle port 63 leads from
aperture 71, passages 61 and 59‘ to the surface of the
the mixing conduit 3 anterior to the edge of the throttle
fuel in the metering tube channel 59. The fuel, under
16, when it is in its closed position into cavity 72 to
provide air to mix with fuel from passage 61. Apertures
atmospheric pressure, in bowl 46 is forced upwardly
through the hollow metering tube 37 into passage 61.
64 are provided in the throttle valve 16, as shown in 20 Simultaneously, air will bleed through the apertures 58
FIG. 6, for .the passage of additional idle air through the
exposed to the air ?ow in the conduit 3 so that there is a
throttle, when it is in its closed position. An idle adjust
flow of a mixture of fuel and air through the upper end
ment screw 66 is threaded into bore 70 to control the
of the metering tube 37 and through passage 61 into
amount of idle fuel and air mixture passing from cavity
the body chamber 72.
72 through an idle feed aperture 71, which connects
This mixture of air and fuel provides the idling opera
bore 70 with conduit 3 and opens into mixture conduit
3 posterior to the throttle 16, in its closed position.
tion of engine E. Adjustment of the idle screw 66 will
provide the correct amount of fuel and air mixture
A cam 67 having an inclined surface 68 is integral
through the idle feed aperture 7.1. The size of apertures
with the control arm 21 for slidable engagement with
58 in tube 37 determine the amount of air to be mixed
head 38 of the metering tube 37. Rotational movement 30 with the fuel for idling purposes. These apertures 58
of the control arm 21 and cam 67 will move the metering
are non-directional and are not affected by their position
tube ‘37 axially to vary the quantity of fuel passing
in the conduit 3.
through the ori?ce 34. The lower end of the metering
tube 37 may be provided with one or more sections of
different diameters, as shown in FIG. 9, or may be formed
with a long tapering surface, whereby the flow area
through the ori?ce 34 can be varied responsive to axial
movement of the metering rod. As for example, the
tip 36 of tube 37 provides a high speed flow of fuel
through ori?ce 34, while larger section 39, when inserted
into ori?ce 34, provides an economy ?ow of fuel through
nozzle 26.
In the operation of the carburetor thus shown and
described, fuel is drawn from the tank T and through
the conduit 57 to the intake 54 by the pump P, and thence
through the valve port 56 into the fuel bowl 46 under
control of the ?oat actuated needle valve 53 to maintain
the fuel at a predetermined level within the bowl and fuel
well 29.
During operation of the engine E, the control arm 21
As the throttle opens from closed position with the
engine running, the operation of the carburetor is trans
ferred from the idle system to the main fuel supply
system through nozzle 26. As the throttle valve 16
passes the idle feed aperture 71, the vacuum or low pres
sure in bore 70 is broken and fuel ceases to ?ow through
aperture 71. To aid, however, in the transfer from the
idle to the main fuel feeding system, the idle port 63
will pass a mixture of fuel and air from chamber 72,
due to the low pressure conditions existing at port 63
as the rim of the throttle valve 16 moves over port 63.
By the time, however, that the throttle passes port 63,
the nozzle 26 has become fully operative to take over
the running of the engine. The length of the slot 63
determines when the nozzle 26 takes over the feeding of
fuel to the engine. The idle port 63 can be of a length
determined by the operating characteristics of the engine
turi 7 to cause fuel to be drawn upwardly through the
main nozzle 26 and out through the ports 33 into the
and by the richness of the idle mixture desired. Port
63 may be a slot extending parallel to the axis of mixture
conduit 3 with a length from 0.015" to 0.030", for ex
ample, in the type of carburetor described. The length
of the slot is varied in a direction away from the closed
position of throttle valve 16.
mixing conduit 3.
Further gradual pivotal movement of the control arm
cessfully operated with a ‘two cycle 60 HF. engine, the
21 moves the throttle valve 16 toward its full open posi
venturi 8 of the carburetor was one that has a 13/16"
is manually pivoted to move the throttle valve 16 to a
partly open position. The air ?ow through the mixture
conduit 3 forms a sub-atmospheric pressure area in ven
In a carburetor of the type described above and suc—
tion and permits the spring 39 to raise the metering tube
diameter. The jet size 34 of the carburetor was 0.098.
37 as the latter passes along the inclined surface 68 on 60 The high speed diameter rod section 36 was of 0.058”,
the cam 67 to thereby increase the flow area and the
while the economy speed section 39 of tube 37 was of
volume of fuel flowing through the ori?ce 34 for passage
upwardly and out through the upper end of the main
nozzle 26 into the center of the mixture conduit 3.
When the throttle valve 16 is opened quickly to pro
0.079” diameter.
Certain structures have been described herein which
will ful?ll all the objects of the present invention, but it
is contemplated that other modi?cations will be obvious
vide rapid acceleration of the engine, additional fuel and
to those skilled in the art which come within the scope
air is drawn from the well 29 through the openings 31
of the invention as de?ned by the appended claim.
into the main nozzle 26 for discharge therefrom into
I claim:
the mixing conduit 3.
A carburetor for an internal combustion engine and
By providing a manually operable mechanical means 70 comprising a bodly including a mixture conduit adapted
for simultaneously operating the throttle valve 16 and
to be horizontally disposed and having an inlet, an outlet
metering tube 37, the quantity and proportion of fuel
and a venturi surface therebetween, a throttle valve in
and air may be accurately controlled to effect a material
said outlet, a throttle shaft journaled in said body and
saving in fuel and an improvement in engine performance
secured to said throttle valve, a fuel bowl mounted on said
during idling, part throttle, acceleration, and full throttle. 75 carburetor body, means forming a tubular fuel passage
extending from said body and terminating at one end in
axial fuel passage, and mechanical means to actuate said
said bowl, a main fuel nozzle formed at the other end
of said fuel passage means and projecting through said
venturi surface into said mixture conduit, means forming
in said one terminating end of said fuel passage a meter 5
throttle valve and metering tube simultaneously to variably
proportion the fuel air mixture supplied to satisfy engine
requirements at different speeds, said mechanical means
comprising a spring biasing said metering tube in one di
ing ori?ce, a movable metering tube extending through
said mixture conduit and said nozzle and having a tapered
rection, a control arm secured to said thr-otle shaft, and a
cam on said control arm engaging the other end of said
end extending through said ori?ce to vary the flow area
th-erethrough, an opening from said fuel bowl into said
biasing spring.
metering tube for moving said metering tube against said
fuel pass-age means for the diow of fuel from said bowl 10
upwardly through said nozzle, an idle fuel system includ
ing a fuel passage extending axially through said meter
ing tube into a portion of said carburetor body above said
mixture conduit, said metering tube having a port above
said ori?ce connecting said axial fuel passage with said 15
fuel passage means, said carburetor body portion having
an idle vfuel passage connected to said axial fuel passage
and having an opening into said mixture conduit posterior
to said throttle valve, said metering tube having a second
port connecting its axial fuel passage with said mixture 20
conduit anterior to said throttle for bleeding air into said
References Cited in the ?le of this patent
Bioknell _____________ __ Aug. 11,
Ball et al _____________ .. Dec. 17,
Read ________________ __ June 18,
Foster _______________ __ Oct. 20,
Phillips ______________ _- Oct. 20,
Bracke ________________ .._ Apr. 6,
Phillips _____________ __ Mar. 18,
Jones _________________ __ May 30,
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