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Патент USA US3096761

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July 9, 1963
Filed April 4, 1961
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United States Patent O?"
Patented July 9, 1963
reference being had to the accompanying drawing, ‘in
Gordon H. Millar, Mound, Minn, assignor to McCulloch
Corporation, Scott Division, Minneapolis, Minn, a cor
poration of Minnesota
Filed Apr. 4, 1961, Ser. No. 100,657
2 Claims. (Cl. 12.3-119)
The FIGURE is a side elevation of a two-cycle out
board motor and carburetor partially in section.
Referring now to the ?gure there is shown a two-cycle
outboard motor 10 for use in driving a boat through the
water and including a crankcase 12, a cylinder 14, a
water cooling jacket 16‘, crankshaft 17 and piston 18. At
tached to an intake pipe 20 which communicates with the
This invention relates to fuel feed systems: and more 10 crankcase 12 in the usual manner is a carburetor 22.
The cylinder 14 is provided with a pair of integral lon
particularly to a fuel system including means for supply
gitudinally extending ?anges 24 and 26 at the right of the
ing additional fuel to the combustion chamber ‘of an in
cylinder as shown in the ?gure. Attached to the ends of
ternal combustion engine during rapid acceleration of
?anges 24 and 26 is an intake bypass cover 28. The
the engine.
The invention will be described by way of example in 15 opening 30 between the cover 28‘ and cylinder 14 com
prises an intake bypass duct communicating at one end
combination with a two-‘cycle outboard motor.
with the crankcase 12 in the usual way and also with an
When an outboard motor is used to pull a heavy load
intake port 32 provided in the wall of the cylinder 14. At
such as a water skier or another ‘boat, the acceleration of
the left side of the cylinder 14, as shown in the ?gure,
the motor in response to a rapid advance of the throttle
there is a pair of longitudinally extending ?anges 34 and
is often unsatisfactory. With such a load attached to the
36. Secured to each of the ?anges is an exhaust cover
boat, the motor will often tend to slow down momentarily
plate 38. The exhaust cover plate 38 has an exhaust pipe
as the throttle is rapidly advanced. This undesirable
40 integral therewith. Between the cover 38 and cylinder
delay in motor acceleration results partially from the
wall 14 is an exhaust passage 42 which communicates
necessity inherent in may two-cycle motors to pass the
fuel-air mixture through the crankcase before the mixture 25 through an exhaust port 44 with the cylinder chamber 46.
The carburetor 22 includes the usual air inlet 50‘ and
enters the combustion chamber. This delay in accelera
air outlet 52 which, as mentioned above, is connected in
tion response at the time the throttle is rapidly advanced
the usual way to the intake pipe 20‘. The carburetor 22
will thus often cause the motor to decelerate momentarily
also is provided with a conventional ?oat chamber 54
just at the time additional power is most needed.
Another shortcoming of conventional fuel feed systems 30 which serves as a fuel storage means and a ?oat 56.
Fuel is supplied from a fuel storage tank (not shown)
is that the ‘fuel-air mixture will often become excessively
to the carburetor through fuel line 58. The carburetor ‘is
lean at the time the throttle is rapidly advanced. It is
provided with a conventional throttle butter?y valve 60
well known that a lean mixture can cause severe over
pivotally mounted on a pivot ‘61. A throttle control lever
heating of the engine. Occasionally overheating in an
outboard motor caused by a lean fuel mixture will result 35 62 is secured to pivot 61 for controlling the fuel-air mix
ture and the speed of the motor in the usual way. The
in melting or burning out of a piston. This is especially
throttle butter?y valve 66 is operated by a throttle line 64
true when a mechanical spark advance is used.
which is secured to the throttle control lever 62. Thus, by
It has been previously shown that supplemental fuel can
moving the throttle line 64 to the left the control lever 62
be introduced directly into the intake manifold of an
internal combustion engine for the purpose of priming or 40 will cause the ‘butter?y valve 66 to pivot counterclockwise
facilitating starting of the engine. For operation, these
previous devices depend for the most part on ?ooding
of the carburetor, certain pressure conditions in the intake
manifold or the like and do not provide the advantages of
as shown in the ?gure ‘about the pivot 61, thereby closing
the throttle. Clockwise movement of the control lever
62 will, of course, open valve 60. Integral with the con
trol lever 62 is a supplemental fuel pump control lever 66.
the present invention.
4.5 Lever 66 is provided with an opening 68 therein extending
radially from the pivot 61. Operatively connected to the
It is accordingly an object of the present invention to
supplemental fuel pump contnol lever 66 and throttle con
provide an improved fuel feed system which will allow
trol 64 is a connecting rod 72 and pump piston 70‘ attached
immediate engine response to a rapid advance of the
to the lower end ‘of rod 72. The connecting rod 72 is
It is still a further object of this invention to provide 50 provided with a transversely extending pin 74 which ?ts
in the ‘opening 68 of the pump control lever 66. The
and improved means for reliably preventing a lean mix
piston 70 is, in this way, operatively connected to the
ture during rapid acceleration of the motor.
pump control lever and throttle control line 64.
It is yet another object of this invention to provide an
The piston 70 is slidably mounted in a cylindrical open
improved supplemental fuel feed system for an internal
combustion engine which supplies supplemental fuel to the 55 ing 76 formed in the body of the carburetor 22. The upper
end of the cylinder 76 is closed by means of a suitable plug
engine when the throttle is rapidly advanced but not when
78 threaded into the top of cylinder 76. Plug 78 is pro
the throttle is advanced slowly.
vided with a central opening 80 through which passes the
It is still a further object of this invention to provide
connecting rod 7 2. The lower end of the cylinder 76 com
an improved fuel feed system of the type described which
is economical to construct, reliable in operation and re 60 municates with the ?oat chamber 54 ‘by means of a port
82. The port 82 is provided with an enlarged diameter at
quires relatively few additional parts.
83 having a ball 84 therein. The ball’ 84 will seat against
Brie?y stated, the present invention provides an im
annular valve seat 81 under certain conditions to act as a
proved fuel feed system for an internal combustion engine
valve which allows the ?ow of ?uid from the float
including means operatively connected to the throttle for
chamber 54 into the pump cylinder 76 'but prevents ?ow
forcing fuel directly through a nozzle positioned adjacent
of fuel in the reverse direction. The ball 84 can be held
to the intake port and into the intake manifold of the
movably in the port 82 by a suitable retainer ring 85.
engine whereby a stream of fuel substantially unmixed
The pump chamber 76 is provided at the‘ bottom‘ with
with air is introduced directly into the cylinder in re
an outlet port 86 which communicates through a suitable
sponse to a rapid opening of the throttle.
filBl supply line 88 with the supplemental fuel supply noz
These and other more detailed and speci?c objects will
z e 90.
be disclosed in the course of the following speci?cation,
A ‘fuel ‘supply nozzle 90 comprises threaded nozzle
member 92 which is screw threaded into a suitable
threaded opening 94 in the intake bypass cover 28. The
nozzle 92 is provided with a longitudinal bore 96 com
municating at one end with the intake bypass chamber 30
and at the other end with the ‘supplemental fuel supply
The rapid flow of fuel through nozzle 90 results in a
momentary stream 128 of raw fuel through the intake
port 32 and directly into the cylinder chamber 46. It
will be understood, however, that the intake timing of the
normal fuel-air mixture'supplied through the intake by
line 88.
pass chamber 38 as well as the streams of raw fuel 120
will be controlled by the movement of the piston 18
The nozzle 90 may be, if desired, provided with a
constriction 98 at the end thereof projecting into the in
downwardly beyond the intake port 32 in the usual man
take bypass 30. The provision for constriction 98 at the
ner. Thus, during the intervals in the cycle of operation
nozzle opening will assist in breaking down the fuel pass 10 in which port 32 is open, the stream of supplemental fuel
ing into the cylinder from the nozzle to relatively small
120 will pass directly into the cylinder.
size droplets. The requirement for a constriction 98
When the throttle control line 64 is moved to the left
will depend upon a number of factors such as the diam
in the ?gure, the throttle parts ‘62 and 66 pivot clockwise
eter and length of passage 96, the size of the engine and
about pivot 61 thereby elevating the piston 70. When the
the type of fuel used.
15 piston 78 is elevated, the check valve 84 is again moved
Secured to the nozzle 90 by threads 100 is an adapter
away from the seat 81 thereby allowing fuel to be drawn
102 having a relatively large bore at 104 communicating
into the accelerator pump chamber 76 from ?oat chamber
with a relatively small bore 106. A ball 108 provided
54 through port 82. In this way, the fuel supply in the
in the adapter 102 acts as a check valve to ensure flow
accelerator pump chamber 76 is replenished.
of fuel from the carburetor into the intake manifold and
The present invention, although it is relatively simple
to prevent ?ow in the reverse direction.
A spring 118
positioned between the ball 108 ‘and nozzle 90 maintains
the ball 108 in the normally seated position against an
annular seat 107.
The fuel supply line 88 may be secured
in construction and economical to manufacture, success
fully provides a rapid and immediate increase in engine
speed as the throttle is rapidly opened. The rapid ac
celeration response is especially important when the
to the adapter 102 and to the outlet port 86 by suitable 25 engine is heavily loaded. Furthermore, the rich mixture
clamps 112 and 114.
resulting from supplemental streams of fuel 120 supplied
The ‘operation of the invention will now be described.
directly to the cylinder chamber prevents excessively lean
During relatively constant speed operation of the motor,
mixtures as the'engine accelerates, thereby reducing over
the throttle control line 64 will move the butter?y valve
heating and consequent damage to engine parts. The
60, control levers 62 and 66 and the accelerator pump
invention also permits the introduction of supplemental
piston 70 from one position to another relatively slowly.
fuel into the engine only when the throttle is advanced
Thus, as the operator accelerates the motor slowly, the
rapidly and not during relatively slow acceleration there
throttle line 64, control lever 62, butter?y valve 60 and
by reducing fuel consumption and increasing economy of
supplemental fuel control lever 66 will move slowly in a
clockwise direction about pivot 61 and the piston 70 will 35 ‘It is to be understood that suitable modi?cations may
simultaneously move slowly toward the lower end of the
be made in the structure as disclosed, provided such modi
cylinder 76. As the piston 70 is slowly depressed, the
?cations come within the spirit and scope of the appended
check valve ball 84 is held by gravity off the seat 81 Ias
shown in the ?gure. Ball 84 will not be forced against
the seat 81 under these conditions because of the relatively
slow ?ow of fuel over the valve seat 81 in port 82, there
claims. Having now therefore fully illustrated and de
scribed my ‘invention, what I claim to be new and desire
to protect by Letters Patent is:
by allowing fuel to pass from the cylinder 76 through
fuel supply, a cylinder, a piston slidably mounted therein
a 1. In a two \cycle internal combustion engine having a
port 82 and into the ?oat chamber 54. The fuel will
and a crankcase the combination comprising a fuel feed
not pass through adapter 102 into nozzle 90 under these
system including a carburetor, a throttle valve in said
conditions because the pressure of spring 100 holds ball 45 carburetor, an inlet pipe leading‘from said carburetor to
108 in a seated position.
said crankcase, a bypass duct leading from said crank
When, however, the throttle control line 64 is moved
case to said cylinder, said‘ cylinder having an inlet port
rapidly to the right in the ?gure, the butter?y valve 60,
in the side wall thereof communicating with said bypass
control lever 62 and pump control lever 66 will pivot
duct, a fuel' pump chamber communicating with said fuel
rapidly in a clockwise direction about the pivot 61. As 50 supply, a fuel duct communicating with said' chamber, a
a result, the pump vpiston 70 will be rapidly depressed.
plunger communicating with said chamber, said plunger
The relatively rapid ?ow of fuel to the ?oat chamber
being operatively connected to throttle valve to expel fuel
through port 82 will force the check valve ball 84 against
from said chamber through said duct when said throttle
the seat 81 and cause ‘an increase in pressure in cylinder
is opened, a check valve between said fuel supply and
76 ‘and line 88.
55 said chamber, a supplemental fuel nozzle rigidly mounted
As the piston continues to move downwardly the fuel
in- the wall of said bypass duct on an axisextending
moving into line 88 will unseat the ball 108 and pass
through said inlet port, said nozzle being positioned to
through nozzle 90 into chamber 30. The check valve
direct a stream of fuel into said bypass duct and through
formed by ball 84 ‘and seat 81 thus comprises a means
said inlet port, said stream thereby passing directly into
for permitting supplemental fuel ?ow through the nozzle 60 said cylinder when said piston moves out of sealing en
90 upon rapid movement of the throttle to the open posi
The adapter 102,, ball 108 and spring 110‘ thus oom
gagement with said inlet port, said nozzle communicating
with said fuel duct, a pressure responsive valve means
between the nozzle and the chamber to permit the ?ow
of fuel from said chamber through said pressure respon~
in the line 88 and cylinder 76. The seat 81 ‘and ball 84 65 sive valve only when the pressure within said chamber
comprises a second valve adapted to close at a lower
has exceeded a predetermined value, said fuel being
pressure. As the piston 70 begins to move rapidly down
thereby fed continuously from said carburetor through
ward, spring 110 will continue to hold ball 108 in the
said inlet duct into said crankcase and bypass duct and
seated position thereby causing a pressure increase in
directed in a stream from said nozzle into said cylinder
cylinder 76 suf?cient to seat ball 84. After ball ‘84 is 70 only when the throttle valve is opened.
seated, continued pressure increase within cylinder 76
2. In a supplemental fuel feed system for a two-cycle
and line 88 will force the second valve to the open posi
internal combustion engine with a cylinder, an engine
tion allowing fuel to pass through nozzle 90'. The rapid
piston slidably mounted, therein and a crankcase, the
downward movement of the piston 7 0 is in this way able
combination of a carburetor, an intake pipe connected
to close the second valve ‘and open the ?rst valve.
75 between said carburetor and said crankcase, an inlet port
pnise a first valve adapted to open at a ?rst pressure with
in the side of said cylinder, a bypass duct communicating
between said crankcase and said inlet port, a fuel stor
age means, a throttle valve in said carburetor, a throttle
duct on an axis extending through said inlet port, said
nozzle being oriented to spray said fuel along said axis
through said inlet port, a duct communicating between
said pump chamber and said nozzle, a second check valve
control means operatively connected with said throttle,
said carburetor having a cylindrical pump chamber
therein and a ?oat chamber, a pump piston slidably
mounted within said pump chamber, an actuator rod con
nected to said pump piston, said actuator rod projecting
prevent fuel ?ow from said nozzle to said pump chamber,
outwardly from said carburetor and being operatively
without striking the walls thereof responsive to rapid
connected between said nozzle and said pump chamber to
said pump piston being adapted to force supplemental
fuel through said duct and nozzle and into said inlet port
connected to said throttle control means, said carburetor 10
movement of said throttle to the open position.
having a port communicating between said ?oat chamber
and said pump chamber, a check valve in said port to
prevent ?ow from said pump chamber to said ?oat cham
ber, said check valve being adapted to close only when
said throttle valve is opened rapidly and being adapted 15
to remain open when said throttle valve is opened slowly,
a supplemental fuel nozzle rigidly secured to said bypass
References Cited in the ?le of this patent
Viel _________________ __ Sept. 7, 1937
Stanly _______________ __ Apr. 4, 1950
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