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Патент USA US2406114

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Aug. '20, 1946.
2,406,'1 14
Fil'ed' June 5, 1942
3 Sheets-Sheet 2
FIG. 7
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Aug. 20, 1946.‘
Filed June 5, 1942'
3 Sheets-Sheet s
Fla. 6
Patented Aug.'20, 1946
2,406,114 ‘
Robert W. Sloane and Elmer M. Bimberg, Detroit,
Mich., assignors to Bendix Aviation Corpora
tion, South Bend, Ind., a corporation of Dela-'
ApplicationJune 5, 1942, Serial No. 445,864
7 Claims.
This invention relates to carburetors for in
ternal combustion engines such as are generally
used in automotive vehicles and the like, and it
is more particularly concerned with the matter
of securing the proper fuel feed for acceleration
of the engine, an important object being to pro
rate upon acceleration from low or idling’speeds
and at a relatively slow rate during opening of
the power jet or economizer valve.
Still another object of the invention is to pro
vide a compound or multiple stage acceleration
mechanism that is under the control of suction
vide an accelerating mechanism which accurately
in the intake manifold posterior to thethrottle ‘
meets the various requirements of the engine.
valve and in‘ which the major portion of theac
It is well known to those skilled in the art to
celeration pump stroke occurs upon decrease in
provide means for injecting extra fuel during
manifold vacuum in the high vacuum range and ,
opening of the carburetor throttle valve for ac
a small portion of the stroke, 'su?icient to open
celerating the engine and for opening a power
the power jet, occurs in the very low vacuum
jet when the throttle is near its wide open posi
range, the device being inoperative'throughout
tion and/or the manifold vacuum is very low;
a substantial vacuum range intermediate said
One representative type of such devices includes 15 high and low ranges.
" ‘
a pump having a plunger or piston actuated by
A further object of the invention is to provide
a spring and acting under the control of suction
a device of this character wherein the small por¢
in the intake conduit posterior to the throttle
tion of the. pump stroke reserved for opening the
valve. The spring is normally designed so that
power jet occurs with a slight change of mani
the piston will approach'one end of its stroke as 20 fold vacuum in'a relatively low vacuum‘ range.
the manifold ‘vacuum approaches a high value
' Another object is to provide an'acceleratioin
corresponding to idling operations and the other.
pump of ‘this character wherein the length ‘of
end of its stroke as the manifold vacuum ap
the pump stroke is adjustable. ’
proaches a relatively low value, at which time
Still another object is to provide a device” of '
the plunger opens the power jet. In such vac 225 this character that is simple in construction,vv de
uum operated pumps there is uniform pump
pendable in action and relatively inexpensive to
travel throughout the entire range 'of manifold
vacuum, which means that for an equal drop
Other. objects and advantages of the invention
in vacuum an equal pump travel will be ‘effected
will be apparent to‘ those skilled in the art from
whether Or not the throttle is near the wide open
position or just off idle. Such uniform 'distri»
bution of the available pump stroke over the en
tire manifold vacuum range is objectionable
‘the following description or may be ascertained
because an accelerating fuel discharge is required
principles'of the invention may be incorporated
in various forms and the employment of any
structures, arrangements, or modes of operation
from a study of the accompanying drawings in
which several preferred embodiments of the in
vention are ‘shown.
It will be evident that_ ‘the \
only throughout a limited throttle range as the
throttle is opened from the idle position and gen
erally any acceleration pump action when the
throttle valve is beyond said limited range wastes
that are properly within the. spirit of the ‘in
vention and scope of the appended claims is con
It is therefore another important object of the 40
In the drawings:
invention to provide an acceleration pump in
which the major portion of the pump stroke oc
curs through a relatively high vacuum range as
the throttle valve is moved through a limited
the acceleration device showing the piston thereof
range beyond the idling position;
in an intermediate position;
Figure 1 is a vertical section of a carburetor
embodying the invention;
Figure 2 is an enlarged vertical section through
' The present invention further provides, in ad
dition to means for delivering extra fuel‘fo’r ‘ac
celeration purposes, means for increasing the
' '
plunger taken on line 3—3 of Figure 2;
Figure 4 is a sectional view of a carburetor em
?ow of liquid fuel during periods of operation
when the manifold vacuum is low to thereby en
Figure 3 is a horizontal section of the plump
bodying a modi?cation of the invention;
\Figure. 5 is a fragmentary sectional view of a
rich the mixture during operation under heavy
carburetor embodying, another modi?cation of
loads or at high speeds.
the invention;
Figure 6 is a chart illustrating the character,
device of this character wherein an accelerating
istics of conventional acceleration pump action
charge is forcefully supplied at a relatively rapid‘ 55 and the characteristics of the action of the pres.
Another object of the invention is to provide a -
the lower end of cylinder 80, and a vent 90 from
said cylinder opens into the fuel chamber 26 to
relieve any undesired pressure that might other
cut invention, both plotted against manifold vac
uum; and
Figure 7 is a chart further illustrating charac:
teristics of the action of the invention and plot-.
wise occur below the vacuum piston ‘I4. If de
sired, the vent 96 may open into the air inlet
passage I2.
Throughout the speci?cation reference to the‘
The collar 88 has a central opening for slidable
position of various parts or the. direction of
reception of a sleeve 92 which is slidable on rod
movement thereof is made with regard to same
‘I6, said sleeve having "a ?ange 94 adjacent its
as viewed in the drawings, and similar refer
ence characters represent similar parts althoughli 10' lower end and below collar 88 and against which
one end of a small relatively strong spring 96
' where, such parts are modi?ed in structure'and
ted against manifold vacuum.
operation they are given a
erence character.
reacts, the other end of said spring reacting
against the fuel piston ‘I2. A second spring, 96,
which is, large and relatively weak, reacts be
tween the collar 88 and said piston ‘I2.
further differing ref;
Referring more particularly to Figure 11 there
is shown, for purposes of illustration only aipl'ain'
In the supplementary 0r auxiliary fuel sys
tube downdraft carburetor I6 having an induc
- tion passage including an air inlet I2, large and
small venturis I4 and I6 respectively and a mix-_
vture outlet I8 which is attached to the intake
7 tom, fuel enters the cylinder ‘I6 through an inlet '
passage II4 communicating with the fuel cham
ber 26, passage II4 being normally open but.v
having a check valve II6 therein to prevent re
manifold 2| of an internal combustion engine.
rIPhe air inlet is controlled by the usual offset‘
choke. valve 22 and the mixture‘ outlet is ,con
trolled byathrottle valve 24. '
turn flow of fuel during the discharge stroke of
The carburetor is provided with a liquid fuel
chamber 26 having a wenrknown air connection 25
with the air inlet by’ means of an impact tube
fuel reservoir or chamber 26.
. .
Twoj auxiliary fuel discharge systems from cyl
inder ‘III. are shown in the embodiment of the in
' 21 and, having the usual ?oatmechanism 2B. A‘
mainlfuel system includes a calibrated’ fuel jet
36 which receives fuel fromythe fuel chamber 26
and disoharges'same by way'of: fuel passages 32‘
and 34’ into an annular channel 36' in the small
venttlri I6 from which it; is- drawn by suction
t should be noted that fuel'that
may accumulate above piston ‘I2 may ?ow over
the upper end of cylinder ‘I6 and return to the
g the piston ‘I2.
vention illustrated in Figures 1 and 2, both of
which discharge fuel into the annular.‘ channel 36
fin of the small venturi.
‘ ' into. the air stream of the. induction.“ passage
One discharge system, termed the, power or
economizer system, includes passages I26‘, I22
and I24 and is .provided with a power jetregu
lator including a body' I26 and power. jet reg
ulator or economizer valve I28 integral‘ with a
through a slot 38; air being bledto the main fuel
system, through passages 46 and‘42, and open
ing‘s 44 in a, tube 46.. There is further provided
stem, I36 and positioned intermediate the ends
V [ > an idling. system‘including an idling tube 48'. cali
‘ , brated' jet 56. and fuel passages 5-2, 54 and 56,, the
idling fuel being discharged through the well
known idling jet or plug 58, adjacent one edge ‘of
the throttle valve- '2 4, and air is bled to said idling
fuel‘through a passage 66 communicatingwith
theinduction passage and controlled by an ad'
thereof.' One end of said stem extends into
fuel cylinder 16 whereby the piston ‘I2, may
gage same and open the valve I28. 'A spring
yieldingly urges,’ said valve I28 closed.
A by-pass from one side of valve I26 to
other includes a longitudinal passage
through the. valve stem I36, opening atone end
into the cylinder ‘I0. and provided with a lateral
present acceleration device‘ of the-com 455 duct I36 adjacent said end. Below the valve I28 ‘
a lateral, calibrated metering jet I38 connects
pound type wherein the operation thereof is in a
the passage I 34 with the‘interior of the body
plurality'of distinct stages having di?erent char~
I26,.said body, having a calibrated power'jet I46,
acteristics as will be‘ described hereinafter; one
v " justable needle valve 6.2.
embodiment of 'thejinvention being 1 shown" in
larger thanthe jet I38, communicating with pas
Figures-,1. 2 and. 3. The device‘ comprises'a fuel:
sage I26. Thus when the valve I28 is closed
there is a ?ow of‘ fuel through the economizer
cylinder ‘I0 disposed. within the fuel chamber 26,
system metered by the jet I36 andjwhen said
valve is open the fuel is metered by jet I48, the
advantage of the by-pass arrangement being that
accelerating fuel plunger or piston" is. recipro
cably received in the cylinder 19, the complete. 55 it'eliminates the "flat spot” or “hole” which nor
piston assembly of the device including a vacuum
mally tends to appear upon slight accelerations
from the low' speed or idling operation just off
. actuated piston. ‘I4 connected with piston 12 by a
rod ‘I6; The rod'IG is secured to piston 14in the
idle. .If desired, however, the by-pass I36, I34,
although if desired said cylinder may be. ‘suit
ably mounted'externally of the'carbnreton' ‘ An
known manner by a clip ‘I8 in an annular groove‘
and I38 may be eliminated.
in the end of said rod which extends into. the 60
The other auxiliary fuel discharge system,
termed the accelerating discharge system, in
interior of piston ‘I4. The piston 12: is attached
to the rod ‘I6 by means of‘ a keyhole slot 13. ‘c0
cludes ‘passages I42, I44 and an accelerating
nozzle I46 received in passage I24, said nozzle
I46 discharging ‘fuel through'a calibrated jet I48;
It should'be noted that nozzle I46 is of less diam
‘ Above-cylinder ‘I6 is an‘oppositely disposed
. eter than the passage I24v to permit the. how of
vacuum cylinder ??joperably receiving the vac-‘v
fuel from passage I22 through said passage I24.
operating with. groove ‘I5. A. second groove TI‘ is
I . also provided for a purpose that will be herein?‘
after described.
uum piston ‘I4 and having its upper -' end: con
The passage I44 isenlarged through the major
posterior to the throttle valve 24 by suction pas
portion of its length, as shown in Figure 1, ‘and
‘has a gravity actuated check vavle I56 adjacent
sages 82 , 84 and 86 whereby the piston 14 is sub.
the lower end, urged to closed position by a- weight
jected to and controlled by manifold vacuum
which is generallyconsidered as the vacuumfposs
I52; The upper end of passage I44 'is-vented at
I54 to the upper portion of the fuel chamber 26 ‘
terior to. said throttle valve. A collar 88,'pressed'
to prevent fuel'from being sucked fromjet I48
into an annular recess provided‘ therefor, closes‘
when the‘ acceleration pump is not operatin'g',"said
nected with the carburetor induction passage
vent being controlled by’a check valve I 56 which
is closed by the pressure of the‘ acceleration fuel
valve body I 26 and the ?ow of fuel into said body
in passage I44 while the pump is discharging.
The operation of this device is as follows:
Whenthe throttle is at idle the suction in the
sage I62 about the valve stem I30.
intakelmanifold below the throttle is approxi
mately 18 or 19 inches of mercury, which will
raise the vacuum piston ‘I4 to its upper limit of
will be by way of a slot I60 and an annular pass
When valve I28 is open the jet I40 becomes the
primary metering restriction and the by-pass
I36, I34, I38 is substantially. without effect. Con
sequently, the by-pass is effective during part
throttle operation only.
movement, drawing piston ‘I2 correspondingly up
In order that the operation of the present ac
ward and compressing or loading springs 96 and 10 celeration mechanism and its advantages over
conventional vacuum controlled acceleration de~‘
The discharge stroke of the pump is divided pri
vices will be better understood, reference is now
marily into two stages. The ?rst stage comprises
made to Figure 6. ‘The solid line illustrates ‘the
the major portion of said stroke and‘ includes the
characteristics of the conventiona1 or common
piston travel from the upper limit, of movement, 15 vacuum operated acceleration pump action. It
as shown in Figure 1, to the point at which piston
will be seen that vthere is uniform pump travel
‘I4 engages the upper end of the sleeve 92, as
shown in Figure 2. It is effected by both springs
96 and '98 upon a drop in manifold vacuum
throughout the entire range of manifold vacuum
. which means that for an equal'drop in vacuum
in the intake manifold, which is determined by
' through the relatively high vacuum range when 20 the speed of the engine and the position of the
the throttle is opened off idle, and due to the com
throttle valve, an equal pump travel will result
bined strength of springs 96 and -98 the discharge
whetheror not the throttle is adjacent Wide open
position or just off idle. .
is forceful and at a rapid rate. It will benoted
The dotted line curve illustrates the character
that at the end of the ?rst stage ofthe pump
stroke piston ‘I2 is closely adjacent to but spaced 25 i'stics of the action of the present invention, disre
garding the effect of the power jet valve spring
slightly from the upper end of valve stem I351.
When piston ‘I4 engages the end of sleeve‘ 92 no
I32. The manifold‘ vacuum points in inches of
further expansion of spring 96 can occur. There
mercury, used on the curve, are for illustration
only, for by proper proportioning of the strength
after, said spring is ineffective to actuate the pis—
ton ‘I2 and is carried along with the piston as 30 of the springs, the length of sleeve 92, and/or
sembly throughout the remaining portion or sec
varying the total length of the piston stroke these
points can be varied over a large range.
ond stage of piston travel which comprises only a
small part of the total stroke. This second stage
As shown in said dotted line curve, the fuel pis
is effected solely by the comparatively weak spring
tonwill travel from the extreme retracted end of
98 and said stage is reserved primarily for open- - the stroke of approximately .425" to .1" from the
ing thepower regulating valve I28 by piston ‘I2,
oppositeend of piston travel upon a drop of mani
although as said piston is opening the valve it
will also effect a slow accelerating fuel discharge
which improves the operation of the engine dur
ing this transition period. In this connection, be
fold vacuum throughthe range between 13" and
12" of vacuum. There is then no further piston
travel until the manifold vacuum has dropped to V
40 5.5" of Hg, the remaining .1" of pump travel oc
amount su?icient to equal the preloaded force or
curring between approximately 5.5" and 5" of
manifold vacuum during which portion or stage
of the pump stroke the valve I28 of they power
initial tension in spring 96 when restrained to the
regulator is opened.‘
length shown in Figure 2.
If desired the pump stroke may be adjusted
by attaching the piston ‘I2 to groove ‘I't instead
fore the assembly can progress on downward, the
_ vacuum above piston 14 must be diminished by an
Fromthe foregoing description of the inven
tion and its operation it will be understood that
there is a substantial difference in the pressure
characteristics of the spring action of the two
stages and consequently there is a substantial in
termediate vacuum range wherein "no movement
of the piston occurs. The lower limit of this
range is that value of vacuum just sufficient to
overcome the force of spring 98 and a slight drop
in vacuum through a very low vacuum range be
of to the groove ‘i5. This will vary the total
length of the stroke inasmuch as the upward
travel of thepiston assembly is limited by the
distance the vacuum piston 14 can travel before
reaching the top of the vacuum cylinder 80. At
tachment of the pistonin the groove ‘I5 provides
a short piston stroke, and attachment in the
groove TI provides a longer stroke. Other spac
' ings of the grooves and/or additional grooves may‘
however be provided or other means for adjust?
low this value will permit said spring to actuate
the piston ‘I2 which will thereupon engage valve
stem I30 and open valve I28. During the opening
of said valve the counter force of valve spring ‘I32
must be overcome and this spring will tend to re
tard or interrupt the movement of the piston.
However the force, of spring I32 is relatively slight
justing arrangement between the vacuum piston
and is readily overcome by spring 98 so that it
‘I4 and the rod ‘I6.
does not adversely affect the proper functioning
In Figure 7 the characteristics of the action
of the present invention are shown according to
two piston adjustments. The solid line curve in
of the device.
It should be further noted that spring I32 is
, preferably so calibrated that neither the pressure
of the fuel-in the cylinder 10 during thedown
ward movement of the piston ‘I2, nor suction from
ing :the position of the piston ‘I2 on the‘ rod ‘I6 .
or adjusting the total stroke of the device may
be used,'the illustrated arrangement being a pre
ferred one. Variation in the length of the piston
stroke could also be made by means of an ad
dicates the characteristics of the action whenthe
adjustment is for the short stroke, the longer
stroke being indicated by :the broken line, curve.
the induction passage on the power or economizer 70 The hook or drop in the curve around 5.5‘ to 4.5
inches of mercury is caused by the amount of
discharge system, nor the combination of said
force and vacuum will open the valve I28 prior to
its actuation by the piston ‘I2.
When the piston ‘I2 is at the lower limit of
movement it will rest on the upper face. of the
pre-loading of spring I32 of the power jet regu
lator valve.
It will be noted that the vacuum
points of the device charted in this ?gure‘vary
- somewhat from those shown in Figure6.
2,4316, 1 1.4
let.- Mt. A spring 448 yieldinglvurees th'evalve
is. due to different. spring? maracteriistics: These
points, however, aregalso used only by way of ex
432 closed and is calibrated to maintainsaid valve
in this position against suction on the jet 416.
3 7' ample and may be ‘altered as. desired;
In the embodiment of the invention, shown in
It will be further noted that adjustment of the
‘ » piston stroke varies the; values of vacuum, in the
higher vacuum, range, required to startthe device ,
in motion; This is‘. due tothe fact that varying
the length of therpiston asscmblyzvariesthe rela
tive spacing from the piston 72 to the; collar 88
and. the ?ange 94 of the sleeve 92 when the as
W'sembly is in the uppermost position. This re-i
sults in the compression of the springs as and
Figure 4 a modi?ed type of fuel piston AjIiZis
shown which 'is'provided with a disk 45%) having
a keyhole'ori?ce similar to the ori?ce '13 shown
in Figure 3 sothat said piston may be attached
to rod
To prevent closing of fuel passage - V
435 by the piston 442 when at its lower limit of
movement, lugs 452 are provided which are‘
adapted‘ to engage head 43%! of member 4530 and
space the piston 442 from the head 438; How
98' being correspondingly varied when the'device
ever, if desired, lugs 452jmay be dispensed with
is: in. this position. Consequently, it; will require.
a. vacuum of smaller ‘magnitude to cause the de-‘ 15 and the head-433 may be slotted as shown in.
Figures 1 and 2 or- any other suitable arrangement’
vice to reach the upper limit of its travel when‘
may be provided to insure the ?ow of "fuel from
the piston-His assembled in. groove 75 than when
the cylinder 440. into passage 5218 when the piston
it is assembled in grooved}. At. this point, it
see is» at its lower limit of movement.
will be‘nctedtby referring to .Fieureillthat the;
Cylinder MEI is providedpadjacentthe' ubher
transition‘from the high vacuum range to the lowv
vacuum range will occur after the same amount .
end with an overflow passage 45b and the upper 7
of pump travel from'the upper‘position, regard
end of vacuum cylinder 85 is connected with
the induction passage posterior to the throttle
valve 24 by a passage Q62, said cylinder ‘80 also
has a vent 454; from a point adjacent the lower
end thereof to the induction passage anterior to
' less of the'groove into whichthe piston ‘52 is as-v
- It will be apparent from the foregoing that the
characteristics of. the device may be Varied. by“
varying the length, of the stroke. Moreovenby
also varying the length of/sleeve, 92, and by vary_.
ing the. thickness of the flango?iri of sleeve 92, in.
the throttle valve.
In this embodiment of the, invention'the fuel
is metered by jet 4% when the valve 432 is closed
as said jet is smaller than the calibration of the
‘ ' orderito vary the amount of initial tension in
spring £5 and in- order to, change the time of‘,
transition from, thehigher tothelo-wer vacuum‘
meteringr jet Mil. Upon discharge movement of
range, a considerable number oi‘ operative com-V
discharged from the cylinder 440 is such that it
cannot all pass through jetpétl? and consequently
binations become available without changing the
the accelerating piston 4432,, the volumevof fuel
springs": If the spring’s rates are also varied; >
the valve 532 is forced- open-by the pressure of
innumerable other, operative combinations are,
said fuel. The metering-jet ‘ll-00f the power and
possible; resultingjinia device which maybe read-j
accelerating nozzle 4524 then meters the accelerat
ing fuel charge. Said jet also-serves to meter the
. ily adapted to meet the various: acceleration and.‘
eoonomizer requirements of, different-makes, types:
fuelfor. the power mixture when'th'e power regua
and sizes of engines;
lator valve 432 is openedbypistonMZ.
' ‘
Attention is particularly'called to the fact that
The embodiment of the invention illustrated in
byrlengthehing the sleeve 92;, the length of‘ the
Figure 5 is shown as incorporated in a carburetor
V ?rst stage'of the stroke is shortened in- the higher‘
of similar construction as thatshown in Figure 1_
vacuum range. This is especially advantageous
and‘ the regulator is also similar to thatshown
for engines that do not require so large an initial 45 in the latter ?gure. The accelerating fuel piston,
acceleration charge for satisfactory performance
as; it increases traf?c economy where the throttle
valve is seldom in the wide open position.- .
however, is similar to the one shown in Figured.
Pistons ‘l4 and 442 are connected by a rod 516
which is similar to the rod 16 except that the
upper end is enlarged at 5% to provide a shoul
In Figure 4 Va modi?cation of the invention is
incorporated in an updraft'carburetor M30. In 50 der 5M and there is an enlarged; head EModis
posed within piston it whereby said piston raises
the carburetor as illustrated the mainfuel sys
said rod and piston M2. ' The enlarged portion 5%
tem includes a discharge tube or nozzle 1H2 con-‘
is adapted to pass through an opening 505 in col
nected with the main meter-ingjet (not shown)
by a fuel passage “4' said main metering jet
lar 38 so that shoulder 532 will pick up a washer
506 on the accelerating stroke of the pump, the
‘i being connected with the fuel chamber 25 and
washer being slidable on rod'bl? and engageable
air is bled in the well-known manner to said main
fuel system.
with the under side of collar 88 when the pistons
Within the tube 412; and discharging fuel
are raised, Spring 96 reacts betweenwasher 506
and piston 442 and spring 98 reacts between said
therein, is a‘ calibrated power and accelerating
nozzle 424 of smaller diameter than the inside 60 piston and the collar'88; When the shoulder 502
engages the washer 506" further expansionv of
dimension of tube 412. The power and accelerat-a
ing nozzlev 4.24 is supplied with fuel by way of a
spring 95 is prevented. Varying the length of the
horizontal passage 426 and a vertical passage 4281
enlarged portion 5% effects changes in the opera,
having a regulator adjacent the upper end.
tion of the device comparable to changes-in the
The regulator comprises‘ a body member 439. 65 length of sleeve $2 in Figures 1, 2 and 4.‘
screwed into passage 428 and in which, is oper-l
In' this embodiment there is also but ‘one fuel
‘ably received a- valve 432 intermediate the ends
discharge passage, 568, from the accelerating
of a; longitudinally bored valve stem £34. One‘v
pump cylinder 10 which is controlled by the regu
end of stem lltll‘extends through fuel passage: ‘ .- lator, the passage 508 including’: a power and" ac.
435 which is controlled by the valve 432, said stem?’v 70 celerating jet 510 discharging into a passaige'5l‘2' V
being of smaller cross-section than the fuel pas-j
which communicates with channel 36 in the small
sage 43,6 and'extends into fuel cylinder 440. Lat-1
eral ,f;.ue_l ori?ces 444 are provided adjacent‘the‘
When the valve I28 is'closed, fuel is metered
by the jet I38; and'when' the valve is‘. open, jet,
upper end ofgstem 434 andthelower end’ of the}
bore, is shown as having a] calibrated regulator 75 '5 I ll meters the. iEuel tor the power mixture as well
as the charge of accelerating fuel, ori?ces 530
having a combined area large enough so that they
are not calibrating factors.
While certain modi?cations of the invention
have been shown and described it is to be under
stood that one or more of the Various features of
4. In a carburetor for an internal combustion
engine, an induction passage controlled by a
throttle, a fuel chamber, and a main fuel deliv
ery system: an auxiliary fuel system subject to
suction by air flow in the induction passage; a
regulator valve controlling said auxiliary system;
one modi?cation may be substituted for corre
an acceleration device connected with the fuel
sponding features of another modi?cation, or may
chamber, a pumping member for said device
controlled by manifold vacuum; yielding means
be added thereto. Further, a diaphragm type of
accelerating mechanism, incorporating the func
tions and features of the illustrated piston type
for actuating the pumping member throughout
a major portion of its discharge movement;
means for rendering said yielding means inoper
ative throughout the remaining portion of the
of carburetor or the like as well as the types shown
movement of the pumping member; weaker
and described herein. If desired, there may be
yielding means for effecting said remaining por
an independent accelerating discharge jet or
tion of the discharge movement of the pumping
nozzle‘ discharging directly into the induction pas- ' member; said pumping member opening the reg
sage and the control of the mechanism may be
ulator valve during the movement effected by the
by other means than manifold vacuum.
weaker yielding means; and a discharge passage
It will also be apparent to those skilled in the 20 for accelerating fuel from the acceleration device
art that Various other changes may be made in
to the induction passage.
the form, construction and arrangement of the
5. In a carburetor having an induction pas- ,
parts without departing from the spirit and scope
sage controlled by a throttle valve: an accelera
of the invention or sacri?cing all of its mate
tion device including a fuel cylinder; a fuel pis
rial advantages, the forms hereinbefore described
ton operative therein; a vacuum cylinder con
being merely preferred embodiments of the in
nected with the induction passage posterior to
the throttle; a vacuum piston operative therein;
We claim:
a rod connecting said pistons; a ?xed member;
1. In a charge forming device for an internal
a spring reacting between said ?xed member and
combustion engine: an induction passage; a
the fuel piston; a sleeve slidable relative to said
throttle valve controlling said passage; a source
rod and adapted to engage the ?xed member;
of fuel; a main‘ fuel system adapted to deliver
and a second spring adapted to react between the
fuel to the induction passage from said source; an
sleeve and the fuel piston; said sleeve being so
accelerating device adapted to receive fuel from
arranged that the vacuum piston will engage one
said source and deliver it to the induction pas 35 end of same as it approaches one end of its
sage, said device including a pumping member
having a predetermined discharge stroke and
6. In a carburetor having an air passage con
controlled by manifold vacuum; relatively strong
trolled by a throttle: an acceleration device hav
yielding means for forcefully eifecting a predeter
ing a fuel cylinder; a piston therefor; a piston
mined major portion of the discharge stroke of
rod secured to said piston; means for controlling
the pumping member during decrease of vacuum
the piston by vacuum posterior to the throttle
in a high manifold vacuum range; and relatively
valve; a ?xed member adjacent the piston rod;
weak yielding means for effecting the remainder
a slidable member on said rod and engageable.
of the discharge stroke upon a slight decrease of
with the side of the ?xed member adjacent the
manifold vacuum in a low vacuum range.
45. piston, a pair of springs, one of said springs re
2. The combination with a carburetor having
acting between the piston and the ?xed member
an induction passage controlled by a throttle
and the other spring reacting between the piston
valve, of an acceleration device having a piston
and the slidable member; a shoulder on said rod
with a predetermined discharge stroke and con
adapted to engage the slidable member upon a
trolled by a vacuum posterior to the throttle; a 50 predetermined movement of the piston in one
pair of springs in parallel for effecting discharge
movement of the piston, one of said springs being
'7. In a carburetor having an induction passage
stronger than the other; means for limiting the
controlled by a throttle valve: an acceleration
effectiveness of the stronger spring to a prede
device including a fuel cylinder; a piston oper
termined major portion of the discharge stroke 55 able therein; a vacuum cylinder connected with
of the piston; the weaker spring being effective
the induction passage posterior to the throttle;
throughout the entire stroke of the piston and
a vacuum piston operative therein; a rod con
adapted to independently complete said stroke;
necting said pistons; a ?xed member; a spring
and a valve controlling a passage from the ac
reacting between said ?xed member and the fuel
celeration device and openable by the piston 60 piston; a sleeve slidable relative to said rod and
during that portion of its stroke effected solely
adapted to engage the ?xed member; a second
by the weak spring.
spring adapted to react between the sleeve and
3. In a carburetor having an induction pas
fuel piston; said sleeve being so arranged that
pump mechanism, may be used and the invention
may be incorporated in a horizontal delivery type
sage controlled by a throttle: an acceleration de
vice having a piston controlled by vacuum pos
terior to the throttle, said piston having a pre
the vacuum piston will engage one end of same
65 as it reaches a predetermined position adjacent
the end of its discharge stroke thereby rendering
said second spring inoperative for further dis
springs for effecting discharge movement of said
charge movement; an auxiliary fuel system; and
piston; one of said springs being effective
a valve controlling same, said valve being opened
throughout the entire discharge stroke of the pis 70 by the fuel piston upon discharge movement be
ton, the other spring being effective in coopera
yond said predetermined position.
tion with the one spring to actuate the piston
through part of its stroke only.
determined discharge stroke; and a pair of
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