CA1104011A - Carburetor components and carburetor - Google Patents

Abstract

A B S T R A C T

An improved variable venturi carburetor including one or more improved features such as one or more air valve(s) comprising fuel discharge arifices, upstream of one or more throttle valve(s); backfire protection means in the air valve(s);
layered construction of the air valve (s); overhead biasing means for the air valve(s), with or without related air valve(s) positioning means which may, for instance, assist in enrichment of the fuel air mixture during starting; an arm and ramp fuel metering arrangement interconnected, preferably directly, with an internal bore on a shaft which supports the air valve(s) means for rotation, through which the fuel may be directed from the pickup arm to the discharge orifices in or on the air valve means; ball valve means in the end of the pickup arm bearing against the ramp to assist in minimizing deviations in the arm ramp gap resulting from differential expansion; composite con-struction of the arm and ramp hangar of materials with coefficients of expansion selected to minimize gap changes resulting from temperature changes; various arrangements for fuel enrichment;
improved throttle configurations; spatial configurations of shaft means for the air valve(s) and throttle(s) which facili-tate provision of bearing structure for the aforesaid elements in the body of the carburetor while reducing the proportion of carburetor throat area taken up by the shafting arrangements; and other improvements.

Description

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CAE~BuREToR CO~IPONENTS
AND CARBIJRETOR

BAC~CG~<OUND OF THE INVENTION
The present invention is directed to carbure~or components and carburetors. More particularly, the invention is directed to carburetors capable of providing accurate mix~ure control, and o~ thoroughly atomizing fuel air mixtures, thereby leading to uniformity in the distribu~ion of fuel and air to the cylinders of a multi cylinder engine.
It is known that when a piston engine i5 operatea at uel to air ratios leaner than stochiometric~ the levels oE
NOx, HC and CO in the engine exhaust gases are reduced. Since NOx, HC and CO are generally considered to be the most harmful components of automotive exhaust gases, operation at leaner than stochiometric mixture is a desireable objeckive from the stand-point of controlling pollution. Unfortunately, when piston engines are operated with fuel ~o air ratios leaner than s-tochio-metric, such en~ines generally become considerably more sensitive to ~eviations from uniform dlstribution of fuel and air. Thus, `
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~ when carbureted engines are aajusted for an overall fuel to air ; . ':
ratio substantially leaner than stochiometric, it has been found that some cylinders xun leaner than others, some running sufficien~ly lean to cause misfiring of the engine.
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The roo~ of the problem is inade~uate atomization and distribution of the fuel in ~he carburetor. A portion of the ~` fuel, not successEully dispersed in the air passing through the -;~ carburetor, can ~ollow various paths alon~ the internal surfaces of the carburetor and being preferentially directed to certain of the cylinders ana then to other cylinders either at the same or different throttle settings. Thus some cylinders run at a , ' ' . ' '' .

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c richer mixtuxe at the expense of others. The di~ficulties involved in solving this problem are illustrated by ~he tremendous n~ér -o~ dif~erent carburetor configurations which have been designed with the objective of ob-taining more uniform ~uel distribution~
That the pxoblem has not been satisf~ctoril~ solved is also shown by the exten~ to which the usual principles of carburetor design have been abandoned in recent attempts to solve the problem.
A case in point is the "Dresserator" a venturi valve fuel/air mixing device which seeks to attain supersonic velocity in a throat of variable cross-sectional area, and to meter uel into ~;( the throat in proportion to that area as it increases and decreases.
Viewed against the above background, the improved -results provided by the present inven~ionr including smooth engine operation with extremely low emissions, operation at leaner than stQchiometric mixtures without misfiring and optimum fuel economy, are surprising and unexpected. A
test vehicle with a conventional engine ana equipped with a~
arburetor in accordance with the invention has me~ the 1976 - `emissions requirements o~ both -the United States Federal Govern-- ~ent and the State of California without a catalytic converter or any other emission control devices.
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SVl`lMARY OF THE INVENTION

The invention comprises an improvea carburetor of the ~i variable venturi type and individual carburetor components which are useful not only in variable venturi carburetors but also in carburetors generally.
The improved variable venturi carburetor o~ the present invention includes an induction passage having ups~ream air valve -~

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' means and downstream throttle means therein, defininy a fuel dis- :
charge zone therebe~ween, said throttle means being mounted on shaft means extending along a side or sides of said indu'c~ion,, passage, and said throt~le means including an upper surface por- '~
tion which projects from said shaft means towards the opposite side of said induction passage and is inclined downstream; a plura-lity of fuel discharye orifices positioned at the surface of said air valve means for communicating with said zone biasing means for biasing said air valve means toward a normally closed position and for positioning said air valve means at varying positions between its open and closed positions in response to ~, : respectively greater and lesser flows of air through said air ' valve means; and fuel metering means in communication with said discharge orifices and operable to deliver respectively greater and lesser quantities of fuel to said discharge orifices in response to opening and closing of said air valve means.
: When the fuel discharge orifices are positioned at the surface of the aLr valv~, one can provide for co-ordinated movement ';
of thè.:.o~ific'es.~ -and the air valve, enabling one to consistently `I , '; 20 discharge the fuel into the region of highest air velocity. This is in contrast to known variable ventur.i carburetors having fixed fuel distribution bars in the zone between the air valve and ' the throttle valve, ~hus introducing fuel into a region which has' ~' : relatively low flow velocity under certain conditions, such as for instance at idle and low throttle.
In accordance with a particularly preferred embodiment, a manifold is provided within the body of the air valve running along or adjacent a peripheral surface o the air valve past which the air passes. The discharge orifices may for example extend from this manifold through said peripheral surface at

- 3 -spaced positions along the sur~ace, It is also beneficial and preferred that the orifices be distributed along a substantial portion of the length of the peripheral surface, so that it is introduced across much or all of the stream of air which rushes past the surface~ Internal passages in the body of the valve ¦
member and a shaft on which the valve member is pivotally mounted conduct fuel from a source of metered fuel to the manifold.

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In an air valve molded of plastic r which is a preerred material of construction~ the valve member may be ~or~ed in two layers with all or a portion of the cross-sectiOn of the respective ori-Eices, manifold and passages being ~ormed in the relatively inward surface of one of 5ai~ layers and the remaining portion of said cross-section, i any, being formed in the xelatively inward surface of the other layer. This enables fabrication of the air valve without cos~ly drilling operations and facilitates production o air valves with internal passages even when the valves are of curved or irregular cross-section~
. In a multiple layer construction as above describea, the criticality of achieving thorough séaling of the mating sur-~aces of the two layers along the in-ternal air passa~es can be reduced by lining a~ least a portion of the internal passages with one or more tu~ular members. In one embodiment, such a tubular member may be joined to a lateral outlet opening in a hollow shaft about which the air valve pivo~s, ~he tubular member extend-ing from the outlet opening throu~h t~e passage formed in the valve member body towards the mani~old.
. When the fuel oriices are distributed at spaced intervals in the lip or peripheral surface of the air valve, it is preferable and beneficial that relatively shallow ~rooves be provided in .said peripheral suracc extenaing generally in ~he direc~ion o air flow past the valve The locally increase~ volumes of ~low which stream past the lip at the locations o~ these ~rooves tend . . .
to thwart any tendency which may exist towar~s transverse variation of flow along the lip. -~
A groove formed relatively perpendicular to the direc~
tion of air flow across the lip and locate~ adjacent to the lip in the upstream surface of the valve member can prove advantageous .~ - - - . ' ' ' .
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from the standpoints of increasing turbulence across the lip, performing an air gatheri~g function or the grooves in t~e peri-pheral surface and~or providing a means for producing an additional pressure differential between the air passing the upper sur-face of the air valve member and the air bet~7een ~he air valve and -the throttle.
It is known to protect air valves of varia~le venturi carburetors against backfire damage by providing apertures through the air valve body and a flexible flap on ;-ts upstream surface~

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The flap constitutes a form of check valve which remain,s closed ' during normal operation and opens to relieve internal pressure i~ the carburetor in the event of a backfire. The present carbure-.
tor may optionall~ include a valve member protected against back-~ire by a flap and a plurality of elongated generally parallel slots. These enable one to provide a large availahle open area when the flap is open, without requiring the flexible flap material, to bridge across a wide gap, such as when the backfire protection ~' involves large circular holes throu~h the valve member. By eliminating the wide gap, the slots reduce or eliminate the tendency towards distortion and leaking of th,e flap engendered by wide gaps, and therefore tend to improve operation.
Irrespective of the shape of the back~ire por~s in the valve ' means, the flap can be advantageously secured thereto by a spring cliF -or clamp ha~ing a ~ross-section su~stantially in the shape of a "C".

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For reasons explained belowr it ;s sometimes desireable ~;' to use anair valve which is curved or bent when viewea in end ~"~ ' elevation. When such a va~ve member is provided with back~ire protection, it is advantageous if the flap is molded of flexible , . . .
~,~ material having an undersurface conforming to the contour of the --, air valve upper surface. - -.. . .
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The biasing m~ans may be any suitable type of ~evice capable o~ per~orming the above described biasing function, such as ox instance a counter weight, pneumatic motor, torsion bar, spring or the like. Preferably, the biasing means extends from the upper surface of the air valve means to a support which is overhead the air valve member. Preferably the biasing means is an overhea~ spring means which may be connected to the air valve member either directly or indirectly throu~h intermediate connecting means~ Accor~ing to a particular-ly preferred embodiment of the abDve described type, the connecti~g means may be a tension rod which is connected to a pivot on the air valve member. This pivot moves between two ~ertical planes as the air valve moves from closed to open position. The upper end of the tension rod is secured to a moveable overhead pivot, which is mounted and positioned on suita~le supportin~ means so that it moves up ana down in the space between saîd vertical planes. ~ -Preferably the lateral position of the overhead pivot is such that-as the air valve member swings from closed ~o open position t~e said tension rod swings from a position in which it is inclined to the left of vertical, through vertical, to a position in which it is inclined to the right of vertical; alternatively, the tension rod may swing ~rom right to left. In a particularly preferred .
- embodiment the overhead pivot is supported on a moveable member mounted for reciprocation on a vertical post extending above the ;
j air valve member. The spring means may operate in compressioIi t ~ or tension, and in the latter case may be connected bet~een said moveable member and an overhead support.

~ An optional ~eature is an air valve positioning device to contr~l the position to which the air valve member closes under ~- the in~luence of the biasing means. In its idle position, the air valve is actually slightly open to permit the passage of an - 6 - _ '' ' ' ' ' - . . ~ . , :; . ;, : ::; ., : . . ~., . " . ~ : --. .. . .

appropriate amount of air and fuel for engine idling~ A choke is not essential with a carburetor of the type described herein However, if a choke is not provided it is then convenient to provide for the air va~ve means to assume a fully closed posit.ion to provide full suction for startin~. Thus, an air ~alve position-ing device can be used to hold the air val~e means slightly open when at idle and to cause said means to close fully when the engine is stopped or cranking. Such.devi.ce can also provide a definite stop for the air valve means so that it will close to ~he same idling posi-tion whether closed quickly (with large momentum) or .:
slowly ~with minimum momentum), thereby providing reproducea~le fuel 10w at idle.
A preferred form of air valve positioning de~ice includes a withdrawable obstructing member. The latter is moveable between a first location in which it obstructs closing of the air valve be~ond iale position and a second location to which the obstruct:ing mem~er~is withdrawn so that the air valve can be more fully closed by the biasing means. lhe obstructing means may obstruct the air valve directly, such as by contacting the air valve member itself, or, pre~erably, indirectly, such as by con tacting the biasing means, thus preventing the bia~ing means from r closing the air valve member any further than idle. Manual or ~ :
mechanized means may be provided for moving ~he obstructing member, ; .
such as a choke rod, spring and solenoid combination, penumatic motor or the like. A preEerred example is a rolling d~aphragm-motGr containing a spring which normally biases the obstructing member to -its non-obstruc-ting position and a rolling seal diaphr~gm vacuum- :
motor., energized by a conduit which provides communication between the diaphragm and an area of reduced pressure in the carburetor throat! for moving the obstructing member in~o its obstructing positio~.

' , Any convenient fuel metering system may be employed, but the preferred system is the general category of pickup arm and met~ring ramp type of system an example of which is disclosed for instance in U. S. Patent 3 r 7 52 ~ 4 51 to Xendig. The present inven-tion provides a particularly ~referred improved form of arm and ramp type fuel metering system which may be used in the carburetor of the invention and other carburetors.
A particularly pxeferred form of the presen-t invention has an arm and ramp type fuel meterin~ system, and provides a hollow shaft on which the air valve member pivots. This hollow shaft is inter-connected with the duct means in the air valve member and extends through the walls of the induction passage to a fuel chamber, within which the fuel arm is secured to the ho]low shaft.
A ramp of the known type located within the fuel chamber assists in controlling the flow of fuel from said chamber into a hollow bore in the arm and from thence through the hollow shaft to -the fuel discharge orifices on the air valve means.

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s~ The present invention provides certain optional-improve-,~ ments which may also be employed. These include arm improvements ~, arld cam improvements. These may be used singly or in combination~
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Arm and ramp type fuel metering systems have hereto*ore bee~ criticized because of t~e machining expense involved in ... .
attaining adequate precision in the gap between the end of ~he fuel pickup arm and the contoured ramp. Departures of as little as 2/lO,OOOths of an inch from the predeterminea gap can result in inaccurate mixture control at idle. In the present impr~vements ~he ,. ......................... .
ramp contour tolerances are rendered much less critical by provision of a spring loaded close fitting ball valve in the bore at the end of the fuel arm. The ball makes rolling contact with the ramp and .-- . . . .

, c means are provided to confine the ball against lateral movement . as the fuel arm moves between the idle and ~ e open position : along the ramp. Thus, metering of fuel is achieved by movement of - the ball relative to a metering edge o~ the bore, rather than by changing the gap between the arm and ramp As in the case of the arm improvemen~, the ramp improve- ::
men-ts may ~e used in the present carburetor and others. The arm : improvements enable one to minimize deviations in the.arm/ramp.
gap resulting from differential expansion o~ ~he arm and ramp supporting structure. In the past, carburetors with arm/ramp.
fuel me~ering systems have had a common ~al~ be-tween the carburetor ;.
. throat and fuel chamber, which wall extenas ~rom the ramp to the :;
~:~ shaft which mounts the fuel arm. Unequal expansion of the arm and this wall can vary the gap ~e~ween the arm and.a ramp at different : temperatures.. To minimize such differences in expansion, the ramp ma~ be supported by a hanger means which is carried on and suspended - from the same shaft on which the fuel arm swin~s ::-By selectin~ materials with sui~able coefficients ofexpansion for the arm and ramp hangerr it is possible to produce ~- desired changes in said gap and/or to minimize gap changes result-:-, . . .
ing from differences in tempera~ure. For ins~ance, to increase the uel to air ratio when the engine and carburetor are cold and reduce said xatio when they are hot, one may select a fuel arm with a higher coefficient of expansion than the ramp hanger. For instance, the fuel arm may include both piastic and metal segments in series; or a longer fuel a~m could be entirely o metal while the hanger was of a ma-~erial having a substantially lower coefficient of eY~pansion. A material with almost zero co-efficient of expansion, such as Invar, could be used for the hangex, : . . ' ' . , ' . .

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while steel or aluminum could be used for the arm- ~ny combina-tion of materials which decreases the gap when hot an~ inC~eaSeS the gap when cold is suitable. Alternatively, one may select materials which tend to retain substantially the same gap under both cold and hot conditions, and emplo~ some other means to assist in engine starting, such as for instance the air valve positioning device described above or an enrichment device to be aescribed below~
- As indicated above J a common wall often divides the induction passage from the fuel ch~ber, and pulsation o~ the ~uelf air mixture from the intake manifold back to the carburetor can ~
txanser heat through this wall to the fuel ramp hanger. Assuming the hanger contacts the wall and that the fuel arm is spaced therefrom, theix varying proximity to the wall causes a posi~ive differential in temperature to c1evelop in the ramp vis a ~is the fuel arm as the engine warms up. This causes a pro~ressive change in the arm/ramp gap. Accor~ing to one of the improvements of the present invention, the ramp hanger is spaced inwaraly in ~he fuel chamber from said wall, so that liquid fuel can circulate in said chamber between the wall and the hanger Having been partially or completely withdrawn a suf~icient distance from con~act with ~ ...... . . .
the wall, the hanger can be maintainea at substantially equal temperature with the arm by the circulating fuel.
Another optional feature of the invention is a fuel enrichment sys-tem which may be of assitance for starting. The preferred fuel enrichment system includes a conduit extending ~;
from a source of liquid fuel to a fuel enrichment por-t in the induction passage, said conduit being controlled by an on-off valve. The source of liquid fuel may for instance be the fuel in a fuel chamber which houses an arm and xamp fuel metering device and a conventional valve and float level controlling arrangement.

The outlet port may for instance be in a wall of the induction passage, between the air valve means and throttle meanst or in a flow divider within said passa~e, as aescribed belo~ --- 10 -- .

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A particularly preerred embodiment includes no~ only the above-mentioned on-of~ ~alve, but also a needle valve and throttling orifice in series with the.source of fuel and fuel en- .
richment port to xegulate the maximum flow of fuel ~o said port. ~.
In a particularly preferred embodiment, the conduit to the fuel enxichmen~ port is vented when enrichment is not desired. Still more prefPrably, the on-off valve and needle valve are bo-th mounted in a hollow cylindrical member, the above-mentionea ori~ice being formed in one end of said cylindrical member~ . .
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Irrespective o what orm of on~off valve is used, the needle valve mayl if desired~ be formed o a synthetic resin or ~-other material having a relatively high co-eEficient o~ expans.ion, so that the needle and orifice combination are temperature respon-sive. At higher temperatures, when the needle has expande~ longi-~udinally, the predetermined gap between the needl.e and orifice . :
will thus be reduced, a~tomatically decreasing the available :~
amount of enrichment. Correspondingly, when the engine is cold ..
ana the needle valve has contracted, the gap between the needle and orifice will have been increased, increasing the amount of fuel a~ailable for enrichment. ..
The throttle used in the present invention may take a wide vari.ety of forms; however, it is beneicial and preferred if the throttle member is positioned and shaped so that, whether he throttle is opened or closea the upper surface thereo~ is at a sufficîent inclination to cause runoff of any liquid ~el -which may be present thereon and to prevent accumulation an~
dumping of fuel. Eddy currents formed ~ownstream of the air valve member tend to hold liquid fuel on the upper sur~ace o~
the throttle. The inclination should be sufficient to over-come the effect of these eady currents either alone or in combina-tion with other aids~ Fox instance, an air le~k, descr.ibe~ in . . '' , ', .- 11 ' . .

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g~ea~er detail below, may exist between the air valve and throttle shaft bosses to facilitate removal of fuel from the upper surface of the throttle member.
Certain benefits are obtained if ~he throttle member has an arcuate lower surface, a substantial portion of which is at a uniform radial distance from the axis of rotation of the throttle member. This facilitates maintenance of a seal between said lower surface and an adjoining portion of the caxburetor body.
When the throttle member has parallel ends which are perpendicular to the axis of rotation, this ~acilita~es maintenance of a seal between said ends and the carburetor body. ~ith the bottom being disposed radially relative to the throttle axis and the ends being disposed perpendicular thereto, sealing of hoth the bottom and ends relative to the body is facilitated, and it i5 particu larly preferred that a continuous sealing men~er be disposed in sealing engagement with said ends, bottom and carburetor bod~.
This is of particular benefit in a carburetor having a bod~
molded o synthetic resinous material, in that a simple molded lip type seal can be positioned in a suitable ~roove in the body în sealing engagement with the ends and botto~ of the throttle at the edge of the carburetor throat.

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The throttle member may be hollow or of solid construc-tion~ When it incluaes an arcuate lower surface as above described~
it may have an open or closed hack surface which is on one side of the above-mentioned seal, the upper surface, ends and radial lower surface all being joined together in air tight relationship on the opposite side of said seal. In general, it i~ preferred that the back surface have an area approximately equa~ to that of the upper surface. Assuming the pressures ~n the up~er and back sur~aces of the throttle member are substanti~ the same, the resultant forces tending to rotate the throt~le memher clockwise an~ counter~

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clockwise will be subs~antially in balance. When the throttle member is hollow and its back surace is open, these press.~re forces act upon the top and bo~tom of the member definin~ the upper surface oE the throttle member. When the back is open, it reduces the weight of the throttle member and facilitates its formation from synthetic resin by a molding process.
When the throttle ~ember has an arcuate lower sur~ace as above described, it is bene~icia~ to provide a lip a~ the inter-section between the upper and lower surfaces. This lip may for ins~ance comprise an interruption o the arcuate lower sur~ace which forms an undercu~ at that edge of the upper surfiace past ~ ;~
which the air flows. The presence of such lip is benefiicial in disengaging from the throttle member any liquid fuel which may flow down its upper surface, so that such ~uel aoes not flow down the arcuate lower surface. If the lower surface is undercut beneath the lip so that the tip of the lip is substantially on or within the pro3ected arc of the lower sur~ace~ it is possible .. . .. .
to avoid the unbalanced forces which otherwise tend to open the ,. . . .
throttle spontaneously. If the upper edge of the lip i5 curved, this can be beneficial in reducing noise by reducing or eliminat-. .
- ing pulsation and turbulence in the intake charge as it passes the ; edge of the throttle.

According to one optional but pre~erred variation of the invention, the air valve and throttle are mounted on shaf~s with .
the air valve sha~t being outboard of the thrott~e shaft. Re~er-ring to a vertical reference line approximately in the center o~
the region through which ~he induc~ion air flows wi~h the air valve and throttle in the full open position, the air valve shaf~ is at a ~reater horizontal ~is~ance from said reference line than the throttle shaft. This provi~es a number of advantages. For example~
it facili~ates providing suEficient bearing structure for both the air valYè and throttle shafts in the induction passage walls with--o~trequiring the air valve sh~fts to be ei~her elevated excessively above the throttle or located so far inboard that the air valves reduce the ~vailable throat area of the carhuretor. Placing the throttle shaft inboard of the air val~e shaft reduces the hori-zontal space re~uired to house the throttle, thus enabling the hori zontal dimensions of the carburetor body to be reaucea. More-over, with the throttles inboard of the air valve, there is less surface of the throttle valve exposed to backfire blasts, and there~
fore less effec~ive force is exerted on the throttle shaft and t~e remainder o~ the structure. Less ~orce is requîred to open the ~
throttle against the diferential be~ween -the metering suction and upstream pressure which exists behind the ~hrottles~ There is less deflection o~ the throttle shafts. I the air valve biasing means include lever arms (also called tension rods) as described above, i. . .
~'! there is a certain change in the angle between the tension rods and the upper surface of the air valve member as said member swings from closed to open position. This change in angle varies the force .~ .
vector exerted on the air valve by the biasing means. When the air valve shaft is outboard of the throttle shalt, it permits one ;~
to provide the air valve member with a longer levex arm which în turn tends to reduce the change in anyle described above.
From the foregoing it may be seen ~hat ~he outboar~
arrangement of the air valve shaft positioning yields some advan-tages which may exist irrespective of the form of biasing means employed, while yielding a further advantage which results when the outboard air valve shaft feature is used in conjunction ~ith the b;asing means having the swinging tension rods and vertically reciprocating hanger. Thus, the outboard air valve shaft feature and swinging tension rod features may be used to advantage either alone or in combination , `''''''' ' ' ' ''f'' '' ' ~ .

When using outboard air valve shaftsr it is beneficia to employ an air valve which, when viewed in side ele~ation~ has a curved or bent ~hape so that the air valve reaches across the throttle shaft and down into the throat when the air valve and throttle are open. For instance, the air valve may have a goose-neck cross-section. This minimizes the space which must be provided between the lower surface of the air valve and the upper surface of the throttle when they are in the closed position and enables the air valve to lie flush on the upper surface of the throttle when both are wide open, thus minimiziny restriction of the throat.
Irrespective of whether one uses outboard air valve shaft mounting or not, it will o~ten be convenient to orm the air valve and throttle members of synthetic resin havi~g bosses, i.e. areas o~ enlarged cross-section when viewed in end elevation, -~
formea around their axes of rotation. These bosses may for instance be formed around bores in the air valve and throttle, through wh;ch bores their respective shafts pass between opposite sides of the induction passage. In a preferred embodi~ent of the invention, the carburetor is provided with a boss on the throttle an~ a c]osely adjacent boss on the air valve, said b3r~3 having a small clèarance between them. This clearance is suf~iciently small to direc~ the main flow of air around the tip of the air valve, rather than around the boss, but is of suficient size to cause some air to pass arouna the boss and over the upper surface of the throttle to purge fuel from said sur~ace in a manner discussed above. If desired, one may provide a seal or seals on either or both of these bosses to close the above mentioned clearance. If desired, ~he seal may be arranged in such a manner as to move in or out of sealing engagement 7 depending on whether the engine is stopped or running. Thus r for example, the seal may be arranged on one of said bosses extendin~
generally parallel to the axis of rotation and positioned so that the seal engages the opposing boss when the throttle and air valve ~ - 15 -., ,: , , , .: ~ , are closea ana disengages therefrom, to eliminate ~riction, as the throttle and air valve open.
The above described air valve means and throttle means may each comprise one or more moveable valve members- For instance, the air valve means may be a single air valve member which performs its valving ~unction in cooperation with an aajacent portion of the carburetor body. Similarly the air valve means may be a p~urality of air valve members which per~orm ~heir valving function either in cooperation with one another, or in cooperation with one or more adjacen-t portions of the carburetor body, or in simultaneous coopera-tion with one another and with oné or more aajacent portions o~ the carburetor body. What is said above in respect to the air valve means is equally true of the throttle means.
In carburetors having plural air valve members or plural throttle valve members or both, it is advantageous to provide means for substantially synchronizing the movements of the several air valve members and the several throttle mem~ers. This may be accomplished for example, through the use o~ gearin~, chain and sprocket or cable arrangements familiar to persons skilled in ,he art. Preferably, the synchronizing means in carburetors having plural air valve members is the biasing means~ For example, when the biasing means includes a vertically reciprocating member and tension rods as described above, the u~per pivot supports for the tension rods for each of the air valve member5 can be mounted on the same moveable member and therefore move in unison. According to a pre~erred embodi~ent, the synchronizin~ means for the throttle members is a rotation-reversing lever linka~e comprising a lever on a first throttle shaft, a bell crank on a second throttle sha~t and a connecting link so positioned tha~ rotation of the bell crank in one direction causes opposite rotation of the lever.
Such a linkage will not keep the throttles exactly in phase ' . . ~

,-, t oughout their travel, bu~ will work sa~is~ac~orily if set so ~hat the throttle~ are in phase in the closea position.
In carburetors having plural air valve members and throttles, it is par~icularly preferred that each throttle member and each air valve member be mounted for pivotal moveme~t on its own individual shaft. Still more preferably, the respective shafts are located at the edges oE andjor outside the envelope formed by upwardly projecting the outiine of the induction ;
passage outlet.
In a particularly preerred embodiment o~ the invention -the carburetor includes an in~uction paSsage which is sub-divided by a vertical dividing member into two adjoinin~ throats~ An air valve member and throktle member are provided f~r each throat, the respective air valve shafts, throttle sha~ts and divider being situated in parallel vertical planes.
An optional advantageous embodimen~, applicable when there is a diviaer, is to extend the tips of the throttle valve members, when viewed in closed position, beneath and closely adjacent the lower edge of the divi~er. This has the advantage of tending to maintain axial flow even if the throttles do not open and close in exact synchronism~ This conEigura~ion makes the adjustment o~ the linkage joining the two throttles less critical and tends to reduce or eliminate a suction feed back effec-t on the air valves which might otherwise exaggerate any difference which mi~ht exist in the fuel flow through one air valve as compared to the other.
Another optional emboaiment, applicable when there i5 a divider, and when there are separate air valve members provided in the throats on each side of the divider, is ~o provide each air valve member with its own separate uel ~etering system.

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~G4~1 en one has the option of introducily hydrocarbon fuel into both throats or introducing hydrocarbon fuel such as gasoline into one throat and alcoho~. into the other throat~ The burning oE
alcohol in tRis manner may reduce the ~eak combus~ion temperature in the engine thus reducing or substantially eliminating NO~
emissions.
Additional features of the invention may be foun~ in the accompanying drawings and xelated Detailed Description of Preferred Embodiments set for~h below BRIEF DESCRIPTION OF THE D:RAWINGS -In the accompanying drawings:-Figure 1 is a vertical section perpendiculax to the axes of the air valve ana throttle shaEts of a single throat carburetor constructed in accordance with the invention~
Figure 2 is a vertical section perpendicular to theaxes o~ the air valve and throttle shafts of a double throat .
carburetor constructed in accordance with the invention.
- Figure 3 is a perspective vie~ of what is presently considered to`be the best mode of practicing the in~ention~
. F;.gure 4 is a view o the body of the carburetor of Figure 3 taken from the same perspective but with the cover, Euel metering system, air valvesr air valve biasing means and throttles removed for clarity, and with a portlon of the body broken out to show the construction and sealing of air val~e and throt~le shaft : support sub-assemblies.
Figure 5 is an exploded perspective view of one of the air valves of the carburetor shown in ~igure 3r , ~ Figure 6 is a pers~ective view of details of assembled .. ~i~
- ~valves, with tension rods and throttles being shown in phantom ~:
outline Fiyure 7 is an enlarged ~ortion of one of the a.ir ~alves shown in Figure 6.

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: - 18 - .-- c Figure 8 is a broken ou~ and enlarged portion of the cover, air ~alve and air valve biasing means of the c~rburetor of ;;
Figure 3, also showing details of an optional air valve position- ~
ing device. . . ~ --Figure 9 is a partia? section taken along secti~n line ~-9 of Figure 8. -Figure 10 is a broke~ out ~artially exploded portion o ~ the perspective view in Fiyure 3, showing details of the air .
: valve mem~er, the fuel meterin~ system, and their interconnection.
Figure 11 corresponds to a portion ~f Figure 2, and .~
shows an.air valve and throktle moved to the positions which ~ :
they oc~upy at idle.
Figure 12 i5 a sectional view of the fuel arm o Figuxe 10.
L~6~
. Figure 13 is ~-portion o.Figure 12, shown in cross-. section.
Figure 14 is a sectional view taken along section line 14-14 in Figure 13.
Figure 15 is a diagral~ati.c perspec~ive view of a con-ventional arm and ramp fuel metering system Figure 16 is a diagra~atic view of an .improved arm and ramp fuel meterin~ system in accordance with -the present invention, demonstrating the principle of operation of ~he embodiment dis-closed in Figures 10, 12, 13 and 14.
Figure 17 is a gra.h illustrating how the arm and ram~
.fuel me~ering systems of Figures 15 and 16 differ in sensitivity to deviations in ramp dimensions.
Figure 18 is an enlargement of tha~ portion of Figure 4 which includes the float chambers, to which has been added floats, float val~esr fuel arms and fuel ramps.
Figure 19 is a portion of Figure 2 to which has been add-ed a showing of seal~ng ~eans for the ends of the throttle members~

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: ~,09~$

Figure 20 is a perspective vie~ of th~ flow divider, throttle members, throttle seals, throttle shafts and throttle linkage employed in the carbure-tor of Figure 3.
Figure 21 is a schematic diagram of a fuel enrichment . system.
Figure 22 is a broken out portion, partially exploded, of the fuel enrichmen-t s~stem of the carbure~or of Figure 3.
:Figure 23 is a sectional view along section line 23~23 of Figure 22.

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c DESCRIPTIo~ OF TlI~ PRE~ERRED
EL~BODIMENTS
",.~.
Figure 1 illustrateS the internal construction o~ a ~
carburetor in accordance with the invention. Such a carburetor ,~ , may for instance include a body 1 having a cover 3 securea -thereon wit!, an intervening seal 2 to prevent air and fuel leakage. Cover 3 in~
cludes an inlet 4 and a flange 5, on which an air filter (not.
shown~ may be mounted, Inlet 4 leads to an induction passage 5 which extends through body 1 to an outlet 7 Fonnected to ~he ~:
engine manifold ~not shown)~
Within the upper portion of induction passase 6 is air valve 11 which may be of any convenient shape. However, it preferably has a boss 12 and integrally for~ed body portion comprising upper an~ lower surfaces 15 and 16, a first side 14, a second side (not shown), an~ a tip 21 The air valve is provided wit}l uel dischar~e ori~ices and duct means to deliver fuel to the oriices These ori~ices may for instaDce be in separate conduits secured. to or ad~acent-the surface~of the air valve, or may be forrned integrally with the air valve. Integral orifices and ~ucts have the advantage that they may be located within the body'of the air valve, such as ~or example, fuel discharge orifices 2~ extendin~ through tip 21. These in ~urn connect to manifold 23'and duct means 24, which are also wit~in the body of the air ~ralve.
The air valve is mounted on shaft means 25 receivea '' in a bore 13 extending through the air valve boss 12~ This shaft is mounted in suitable bearing support means in the carburetor end wall 8 and in the opposite end wall (not shown~. At leas~
one end o~ air valve sha~t Z5 may extend through its respective end wall, and has a bore 26 within it to provide communication between an external source of metered fuel (not shown) an~ ~he duct means 24 in the body ~f the air valve.

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-- 2 1 -- _ . ' : .
'.' ' , ."..
- ~ . . . ... . ., . -1~46~

A throttle shaft 29 is mounted in suitable bearing support means in the above mentioned carburetor end walls.
A throttle o~ any convenient shape may be secured for rotation on said shaft. The throttle 30 is merely exemplary of a wiae variety of throttle shapes which may be selected~ Thus, for instance, the throttle 30 ~a~ include upper, lo~er and back surfaces 31, 32 and 33, first end sur~ace 34 and a second end surface (not shown~ it is desired to provide a positive stop against which throttle 30 may close, the throttle lip 40 ; -may engage a stop, such as for instance undercut 36 in the wall of body 1.
The car~uretor will normally bé mounted o~ the intake manifold of an internal combustion engine, such as for instance, a piston type automotive engine. Throttle sha-Et 29 will be connected to any suitable throttle control, such as for instance an accelerator pedal~ hand throttle, automatic governor or other automatic control.
The air valve 11 and throttLe 3~ are shown in their normally closed position. With the engine running, rotation Qf throttle shaft 29 clockwise will open throttle 30 up to and including its Eully open position 30A. Ensine manifold suction on the air valve lower surface 16 will cause the air valve to open towards its full open position llA a~ainst a closing force supplied by a biasing means (to be descri~ed hereinafter).
Metered fuel from the external source (no~ shown~
passes through bore 26, duct means 24, manifold 23 and ~uel dis-charge orifices 22 into the air which is drawn throuyh induction passage 6 by en~ine suction. By virtue of the fact that the ~uel ~ischarge orifices are on the air valve, the ~uel can be discharged into a fuel discharge zone in which the air is moving at high velocity, thereby facilitating a~omization.

' .' '''' '' . ' ' ' - .- '' ' ~' - 22 - ~
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As shown in Figure 2 the invention is rea~ily adaptable to carburetors with multiple throttles and air valves. ~igure 2 discloses a carburetor having a body 41 to which cover 43 i5 ~:
secured in air and fuèl tight relation5hi~ with the ~ssis~ance o seal 4~. Like the previous embodiment, this carburetor has an inlet 44 through upper body ~lange 45 on which an air filter (not shown) may be mounted. Induction air ~ay pass from inlet 44 through induction passage 46, which is divided by divider ~9 into a first thxoat 47 and second throat 4~, past air valves 11 and throttles 30 as described in the above e~bodiment, and depart through outlet 50. If desired, persons 5killed in ~he art wi~1 have no difficulty adapting the principles o the invention to carburetors having addltional throats, air valves and throttles.
The presently preferred embodirnent oi Figure 3 can be fabricated of any convenient material, but many of its com-ponents, includiny body 51 and cover 59, are preferably formed of rigid, impact and heat resistance s~nthetic resinous material, such as for instance polyphenylene sulfide resin sold by Phillips Petroleum Compan~ unaer the trademark Ryton ~, and de5ignated as R-4. The body includes an integral or, pre~erably ~eparate flange 52 for mounting the carburetor on the intake manifold of an engine in any suitable manner~. The probabilit~ of damaging the carburetor flange by bending or overtightening may be reduced by using a ~astening arrangement includlng a clamp 54. Clamp 54 includes a first foot 55 which engages the top surface of flange 52, a somewhat longer second foot 56 which extend~ into depression 53 bu~ does not contact the bottom of the depression, and ~hird foot 57 which contacts the machine~ suxface Qf the mani~old ~not shown) which surrounds the car~uretor. When a bolt ~not shown) is inserted through hole 58 in the clamp and screwed into a .

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th.eaded hole ~not shown) in the manifold surface, the carbure~or - may be secured ~ight a~ainst the manifola surface without exert-ing bending forces on the marginal edges of the flange 52. The ': clamping forces are exerted on the upper sur~ace of the flange by the first foot 55 which is well inboard of the flange margi.ns Figure 3 shows the carburet~r with its cover 59 bolted in place-with bolts 60. A boss 61 and corresponding bore 62 . ,;~
formed in the co~er serve as a mounting for the valve body 63 of a fuel enrichment system to.be discussed below. Cover 59 also includes a bridge 67 having legs 6~, 65 and 66 be~ween which are openings 72 for the admission o induction air~ Legs 64, 65 and 66, ormed integrally of the same synthetic resinous material , as the cover, extend upwardly and inwardly ~o join with a horizontal plate 68 beneath which is formed an integral. slug ~9. The latter ';~
serves as,a rnounting ~or a post 70 and various ad~ustment sc.rews to be described hereina~ter. Threads 71 on post 70 are proviaed '~
for a fastening nut for an air filter (not shown) which will cover -the plate 68, legs 64, 65 and 66 and seal agains-t a ledge 73 ~.
benea~h and adjacent the ends of the legs. ' ~;:
' Visible.through the openings 7~ and cover 59 are first air valve 75, second air valve 76 and flow diviaer 77 and air valve biasing means 80. In this embodiment~ a s~ooth portion 81 of post 70, ex-tending from slug 69 downwardly to flow divider 77 is included in the air valve biasing means... ~ yoke 82 is , ' ~:
mounted for vertical reciproca~ion on the a~orement;.oned smooth portion 81. Yoke 82 includes firs~ and secona arms 83 and ~4 which proiect outward over the air valves 75 and 76 and carry a first fulcrum 85 and second fulcrum (obscured by leg 65).
Suspended from these ~ulcrums are first and second tension rods 85 and 87 connected with pivots (not shown~ secured in depressior,s in the upper surfaces o~ the air valves. Fir5t and second springs 88 and 89 suspended from slu~ 69 are,tensioned to exert upwardly - , . :. ' ,, - 24 - 7 ' ' . . ~ .

directed force on yolce 82, thus biasi~g air valves 75 ~nd 76 upwardly towards their closed position.
Figure 4 shows the carburetor of Fiyure 3 with the ~.
cover and other portions removed, exposing the interior o body 51. The carburetor body incl~ldes ~ront wall 90 rear wall 91 and first and second end walls 92 and 93, ~he latter having respective up-ward projections 94 and 95 The throat diviaer 77 extends between these end walls.
~ irst and second cutouts 95, 96A, 97 and 97A in upward projec~.ions 94 and 95 are provided to receive first and second shaft sub-asse~blies 100 and 110.. First shaft suh-assembly 100 includes shaft support inserts 101 and 1.02 at each end thereof, in which are rotatably mounte~ air valve shaft 103 and throttle shaft 105. Throttle shaft 105 includes a throttle shaft exten-sion 106 which extends outwardly of inser~ 102, so that it projects outside the assembled carburetor. Air valve shaf~ 103 incluaes.
an extension 104 which projects outwardly of shaft supp~rt insert 101 and into the fuel chamber o~ the carburetorr as will be dis-cussea below in connection with Figure 10. Air valve shaft 103 includes a hollow bore 107 in communica~ion ~ith a laterally extending conduit 108 which extends into the in~erior of the air valve member, which will be ex~lained in grea~er detail below in connection with Figures 5 ana 6. The second shaft sub-assembly 110 includes shaft support inserts 111 and 112, air valve shaft 13, air valve shaft extension 114, bore 117, conduit 118, . throttle shaft 115, and throttle shat extension 116 which are identical to parts 101 through 108 described above~
.The fuel chamber 120 is mounte~ on one end o~ the carburetor, and shares wall 93 with the carburetor thr~a~ ~he remainder of the fuel chamber is formed by a front wall 121 end wall 122, rear wall 123 and a bottom wall ~obscured behind end wall 122). ~ transverse dividing wall 126 extending between . - ' - - ,' . , .
. - 25 -: -0~

thro~t end wall 93 and fuel chamber end wall 122 divides the fuel chamber into a Eirst chamber 1~7 and a second chamber 128.
A threaded fuel inlet 125 is pro~ided in lront wall 121. The carburetor may ~e operated with a single float and float valve .
in first chamber 127, a fuel transfer aperture tnot shown~ being provided in dividing wall 12~. On the o~her hand, iE it i~
desired to operate the carburetor as a -two floa~ carburetor, such as for instance when supplying dif~erent fuels to each o~
the two chambers 127 and 128, the fuel transfer aperture i5 omitted and the chamber 128 is provided with its own threaded inlet (not show~) for the admissi~n of fuel. .
In order that there may be a fuel and air ti.ght seal between the body 51, shat sub-assemblies 100 and 110 and cover 59, the flange 133, end walls 92 and 93 and sha~t $ub-assemblies 100 and 110 are provided with grooves 134 along their edyes.
Seals 136, 137, and 138 in these grooves are clamped tight~
when the cover 59 is secured to body 51.
Figure 5 illustrates the details o~ the air valves of the carburetor of Figure 3~ As shown in Figure 5, the air valves may be fabricated in a plurality o layers, ~or instance upper and lower layers 140 and 159 shown in Figure 5. The upper layer includes a boss portion 141, one lower surface o~ which constitutes a segment 142 o~ the bore for the air valve sha~t. Boss portion 141 also includes a ~lat land correspondin5 in size and shape ~o -; a corresponding land 163 on the lower layer l59- Boss por~ion 141 also includes an upwardly and rearwardl~ diverging sur~ace 145 which is useful for retaining a spring clamp as ~escribed below.
Back sur~ace 144 extends between land 143 and diverging sur~ace . 145.

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Exten~ing from b~ss portion 141 is a humped ~late section 146 having a side 147 corresponding to one end o~ the air valve a top surface 148 corresponding to the uDstream sur~ace of the air valve and a bottom sur~ace 149 which mates with the top surface lSB o~ lower layer 159~ Distributed across humped -~
plate 146 are alternating narrow bars 151 and slots 150, the latter passing all the way through the hu~ped plate~ A central portion 152 includes a depression 153 in which may be secured the lower pivot for a tens:ion.rod such as the tension rods 86 ~' and 87 shown in Figures 3 and S.
Lower layer 159 also includes a bo5s portion 1S7. It defines in part a segment 160 of the bore which surrounds the air valve shaft, such as for'instance the air valve shaf~ 103 shown in Figures 4 through 6. At the intersection between the aforementioned segment and the back surface 161 of boss portion 157 is a rib 162. It is adapted to cooperate with diverging sur~ace 145 on upper layer 140 ~or retaining a spring clamp in a manner.to be described below. .
Like the upper layer, lower la~er 159 also includes a humped plate portion having a top surface 158, side 156 and bot.tom surface 155, the,latter coxresponding to the downstream ' surface o the assembled air valve.
Humpea plate portion 164, like ~he corresponding por-tion of upper layer 140, includes elongate~ bars and slots 166 and 165 which are o~ the same size as the corresponaing bars.an~
slots 151 and 150 in upper layer 1~0. ~ cen~ral portion 170 of the lower layer includes an openin~ 171 of sufficient size .
to receive the depression 153. The,opening 171~ bars 166 and slots 165 are arranged to be in reglstry with the depression 153, ,hars 151 and slots 150 of the upper layer when the upper and' lower layers are,assembled with their side edges 147 and 15 : in coplanar relationship.' . . . .
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- - . - 27 -....

- ., . ~ ., .... ... , :

A groove 167 e~tendS through central portion 170 of lower layer 159 from the segment 160, which partially ~eEines the air valve bore, to another ~roove 168, which is spaced inwardly froin the tip 172 of the lower layer Groove 167 defines a duct means extendina generally perpenaicular t~ the shaft bore and groove 168 defines a ~anifold extending genexally parallel to the air valve shaft. Groove 168 extends along air valve tip 172 over a substantial portion, for example at least about half, of its length. At spaced points ais~r;buted over a substantial portion of the length of tips 172 are short grooves 16~ extending perpendicular to grooves 168 and defini.r,g dlscharye ~ ;
orifices. It should be apparent that the grooves 167, 168 and 169 can be formed in top surface 158 of lo~er layer 15~ or in bottom surface 149 of upper layer 140 or in both of said surfaces.
Multi ~ayer construction of the air valve makes it possible to form the duct means~ manifold and discharge orifices from the above mentioned grooves and makes it po~sible to form the air valve means conveniently from synthetic resin material, including mineral or glass ~ib~r reinforced s~nthetic resins, without arillin~ :
and with less complicated injection mold5 than woul~ be required to form the orifices with withdrawable pins. Moreover the multi-layer construction facllitates formati.on of a humped plate air valve with internal duct means which follows the contour of the humped plate. .
The upper and lower layers 140 and 15~ are intended to be assembled in surrounding relationship with an air valve shaft, such as shaft 103 of shaft sub-assem~ly in Figure 4~
The shaft is formed o~ an appropriate diameter to have a close fit in the bore formed between segments 142 and 160, and i5 o~
sufficient length to extend into the shaft su~port inserts 101 and 102 o~ Figure 4 with the air valve sha~t extension 104 protruding.

- 2~ -1~0~

~ n optional bu~ pre~rred em~odiment includes securing a conduit 108 to shaft 103 with the conduit ~eing in col~unication with the shaft bore 107. The conduit is preferably preshaped to nest within groove 167. When the upper ahd lower lay~rs are assembled with sha~ 103 and conduit 108 in ~lace, the two layers are bonded to one ano~her such as f or instance by thermal, e.g.
sonic welding.
In the comple~ed air valve member the bottom surface 149 o~ upper layer 140 defines the up~er surfaces o~ the auct means, manifold and discharge orifices deined by grooves 167, 168 and 169~ Since it is desireable that the duct me~n5, mani~old and discharge orifices be substantially air tight, conduit 108 performs a useful function. Since it conducts ~uel most of the way from the bore 107 to the groove 168 defining the mani~old, .it renders less critical the formation of an air tight joint bet~een upper layer 140 and the sides o~ groove 167.
The bars 151, 166 and slots 150, 165 provide backfire prote~ction for the assembled air valve. In order to close off the slots during normal operation, flexible ~lap memhers ]75 and 176 are provided. They generally correspond in size to the upper surfaces o the air valves, terminating a short distance inward .
from the air valve tip 21, as more c}early shown in Figure 7~
In order that they will not inter~ere with the operation o ten-sion rods 87 and 86, flaps 175 and 176 are provided with cutouts 177 and 178, leaving the depressions 153 uncovered even when the flap is in the down or closed positlon as illustrated by flap 175 in Figure 6.
Flaps 175 and 176 are secured to their respective air valves by spring cla~Ps I79 and 180, which grip the back edges o~ the flaps with thei~ upper arms, such as bac~ edge 182 - and clamp upper arm 181 on flap 175 anZ spring clamp 17g in ~ ' ' ' . ..... . . .... . , ' k~ ~re 6. Rib 162 on the boss portion 157 of lo~er layer 159 sèrves as a catch for the lower arms of the clamps,.such as for instance lower arm 183 of clamp 180 in Figure 6.
Figure 7 discIoses the grooves which may be ~rovided in or adjacent the tip or peripheral sur~ace of the air valve, perpendicular and/or parallel to the direction of air flow~ ~ -Figure 7 discloses a corner of an air valve 176 formed of upper and lower layers 140 and 159 as shown in ~igures 5 and 6.
The air valve includes a tip or peripheral surface 21 through which extend the fuel discharge orifices formed.by yrooves 163 in lower layer lS9. Grooves 186 extend generally parallel to the direction of air flow through peri heral surface 21, cutting through its upper and lower surfaces 188 and 189~ These grooves are of assistance in inhibiting the shifting of fuel transverse-ly along the peripheral surface under any unstable conditions causing transient motion of air flow transversely to normal . flow and along the tip ~
A`groove 185 may-be formed relatively perpendicular to the direction of.air flow extending along and adiacen-t periphera~
surface 21 in the upstream surface of air valve 76. Such groove can prove advantageous from the standpoint of increasiny the turbulence across khe tip or peripheral surface 21 and .for produc- !
ing an additional pressure dlfferential between the air ~alve and.
throttle in the inducation passage of the carburetor. If the grooves 186 are made deeper so that they cut through the bac~
surface 190 of raised edge 187, groove 185 can then perform an air gathering func~ion for the grooves 186.
Figures 8 and 9 disclose additional details of the air valve biasing means 80 previously discussed in connection with Figure 3, and additional details thereof~ as well as an opt.ional air vaive positioning aevice. Figure 8 shows the post 70 and its .
-.30 -. .
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i~104~

~ h portion 81, yoke 82, first ~nd second arms 83 and 84, first fulcxum 85, firs-t and se~ond tension roas 86 and 87, and ~irst and second springs 88 and 89 depicted in Figure 3~ ever, Figure 8 also shows the second fulcrum 79 which was obscured in Figure 3. Inasmuch as much of cover 59 and all o the carburetor body 51 ~with the exception of ~low divider 77) have been removed, and since the one air v~lve shown in Fig~re 8 has been sectioned intermediate its ends perpendicular to its axis of rotation, it i5 possible to see clearly in Fi~ure 8 the aetail~ of depres-sion 153 ~Figuxes 5 an~ 6) and the lower pivot for tension rod 86.
- As shown in Figure ~ the depression 153 comprises a first side wall 193, a similarly shaped para}lel second side wall (not shown) and a lower wall 192 which follows the bottom contours of the two side walls and joins them toyether in air tight relation~
ship so that the interior of depression 153, which opens into the upper surface of the air valve, is pneumatically i501ate~
from the lower surface thereof. A short pin 191 fi~edly secured in the side walls of depression 153 serves as the lower pivot for tension`rod 86.
In Figure 8, air valve 75 is shown in a nearly closed position. Opening of the throttle to increase the suction beneath air valve 75 causes it to pivot towards its ~ully open position, indLcatea by phantom outline 75A. As air v~lve 75 moves towards positi.on 75A the side walls of depression 153 exert downward.and outward force on tension rod 86, moving it towaras 1~ fully extended position 86~ ~ theprocess, tension rod 86 swings from a ~ownward inclination to the left of vertical, to a downward inclination to the right of vertical. This is because the fulcrum 85 is maintained between the two vertical planes occu~ied by lower pivot 191 when it is in the air valve closed positioD and in the fully open position indicated by phantom ou~line 191A~

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Movement o~ fulcrum 85 ~o its full open ~osition 85A
is indicated by arrow 204. The lateral position of fulcrum 85 is fixed in this embodiment by arm 83, which is bifurcated. Similar-ly arm 84 governs the lateral position of fulcrum 7~. Arms 83 and 84 extend latera~ly from the cylindrical body 205 o~ yoXe 82, which is provided with a yoke slot 194 at its lower end so that it may when ln fully depressed position telescope over the upper edge of flow divider 77.
At the lower end of yoke body 205 are first and second spring ears 195 and 196, to which are secured the lowex ends of sprin~s 88 and 89 respectively. The upper end o spring 88 is secured to the underside of adjusting screw 197 engaged in a threaded insert 198 secured in slug 69. Adjusting screw 197 is accessible for adjustment through the to~ plate 6$ of brid~e 67 through a bore 199. Although not essential, there may he a similar adjusting screw (not shown) in bore 206 attached to the upper end of spring 89. Based on the foregoing, it should be apparent that the biasing means 80 b.iases the air valve 175 towards its closed positionr and that the ~oke 82 reciprocates or moves between upward and downward positions respectively as the air valve 175 closes and opens.
In order -to provide a positive stop for the yoke and air valves, a stop arm 200 extends laterally from the yoke body 205, said arm bein~ partly visible in Fi~ure 8 and more fully visible in Figure 9, from which spring 88 and its adjusting screw have been removed. Stop arm 200 has an upper surface 201 which is aligned with the lower end 203 of adjusting screw 202 ~lich is positioned in a threaded bore 207 located in slug 69 of bridge 67. Adjusti.ng screw 202 provides a positiYe stop for yoke ~2, and therefore for the air valves, which stop can be adjusted by turning the screw.
,-' 3~ , ' .

( ~L' Figuxes 8 and 9 also disclose details of an Optionalair valve positioning device including a withdrawable obstructing means. The latter may for instance prevent the biasin~ mean~ from closing the air valve member any further than its idle position when the engine i5 operating, but causes the air valve means to close fully to develop maximum suction on the fuel while crankin~
and starting. For example, the obstruction means may cooperate ' with an idle adjustment screw 210 threadably engaged parallel to the longitudinal axis of yoke body 205 in a lateral projection211, said screw being held in position by lock nut 212 and having an upper screw end 213 for engaging the obstruction means., The obstruction means may comprise a withdra~Yable ob-structing member such as spade 215 com~rising an axial extension of a rod 216. The latter is mounked for horizontal reciprocation in a bore 217 carried on a partition 218 dependent ~rom bridge plate 6B. Spade member 215, which also appears in Figure 9, includes an a~erture 219 and a barrier or obstructing portion 22 which can be alternately positioned above the upper screw ena 213 of,idle'adjus~ment screw 210 by hori~ontal reciprocation of - . .
~od ~16. ' ' , " When spade 215 is in the position shown in Figures 8 and 9, upper screw end 213 of idle adjustment screw 210 can pass through aperture 219 as the stop axm 200 rises to meet the lower end 203 of adjusting screw 202. Assuming the spade is in this position when the engine is stopped, the biasing means B0 can close the air valves to their fully closed position to develop maximum ~uel suction for starting. When the engine has been started and is running, a somewhat more open position o~ the air valves is aesireable for idling. Consequently, ~hen the engine is running the spade 215 can be withdrawn slightly by right to left movement so that the spade flat portion 220 is directly above upper en~ 213 .

i~4~
~ he idle adjus~ment screw. Thus, spade 215 then obstructs the bi~sing means from closing the air valves beyond idling position.
Rod 216 and attached soade 215 may be moved in and ou~
of its biasing means obstructing position manually or by motor means, such as a solenoid, diaphragm mo-~or or the like. ~here motor means is used it may be manually or automatically controlled. ~ ~:
An example of the latter is shown in Figure ~.
For example, one may use a vacuum motor 221 which is shown exploded in the figure, but is normally mounted against partition 218 and held in place b~ studs, such as s~ud 229 and a cooperating nut.(not shown)r Within t~e vacuum motor housing 222 is a spring 223 which normally urges rolling diaphragm 224 to the righ~. The diaphragm is secured by a 5uitable screw 225 ~o a threaded bore 226 in rod 216~
When the engine is stopped, the spring means ~23 normally urges diaphragm 224, rod 216 and spade 215 to the extended position shown in Figures 8 ana 9. The motor 221 i~
arranged to withdraw spade 215 to a posi~ion in which flat portion 220 is in the closing path o~ idle screw 21~ when the engine is running. This is accomplished by a conduit 227 which connects the interior of housing 222 and the let siae of rollin~ diaphragm 224 to a suitable source of vacuum, e~g. metering suction, such as port 228 in flow divider 77 withln the induction passage o~.the carburetor. The spring tension an~ diaphragm area are calibrated to keep the spade 215 in extended position until the engine , has started, whereupon the diaphragm will urge.rod 216 and spade 215 to the left. Thus, as soon as the air ~alves open, the flat portion of ~he spade will be positioned above the upper end of the idle adjustment screw, preventin~ the air valves from closing past idle position.

- Figure 10 illustrates combined portions o~ the preceding ~
figures. Xn it can be seen the second air valve 76, second tension roa 87 and flow divider 77 of Figur~ 3_ Fiyure 10 also shows _ ~d --elements of the carburetor body 51 shown in Figure 4, including second end wall 93, shaft support insert 101 and rear wall 91, along with elements of fuel chamber 120 including end wall 122, rear wall 123 and dividing wall 126, defining in part the second float chamber 128. Figure 10 also discloses threaded inlet 232 in rear wall 123 of float chamber 128. Some of the details of air valva 76 which have been shown in exploded form in Figure 5 are shown in assembled form in Fisure 10, including the assembled combination of air valve 76 with air valve shaft 103, shaft ex-tension 104, shaft bore 107, conduit lOY and grooves 168 and 169 defining the manifold and discharge orifices~

By means of arrows 230, ~ ure 10 illustrates the communication of the air ~alve shaEt bore 107 through conduit 108 wi.th the ma~ifold and discharge orifices defined by gr~oves 163 and 169. Figure 10 aiso ~rovides orientation between the items described above and the fuel metering system and shows the fuel arm in exploded relationshi~ relative to air valve shaft 103 Although the present invention may employ any conven--ient fuel metering system, the arm and ram~ tyDe is preferred.
In the present e~bod.iment the fuel arm assembly includes a banjo fitting 237 having an internal bore 23~ ada~ted to fit in seal-ing enga~ement on the end of air valve shaf~ extension 104. A
bolt 243 extending through washers 242, banjo fitting bore 238 and internal threads in the air valve shaft bore 107 draw the banjo fitting into the position of outline 237A.
The fuel arm assembly also includes fuel arm 239 having an internal bore 244 which cQmmunica~es~ as indicated by arrows 245, with the banjo fitting bore 238 and air valve shaft c`
1~4 bore 1070 With the fuel arm as~embly in place on air valve shaft extension 104, the ~uel arm occupies the position of dashe~ out-line 239A.
Bore 244 of fuel arm 239 may be of any desired configura tion but pre~erably partially encloses a ball valve 241 which is urged outwardly by spring 24~. Ball ~41 engages ~he contoured upper s~lrface of fuel ramp 233 suspended from air valve s~aft 103 b~ a fuel ramp hanger 234.
The fuel ramp is held in position with the assistance of side and end positioning protu~era~ces 235 and 236~ These respectively engage the side and end o~ fuel ramp 233 and are formed in the fuel chamber flo~r 231.
The surface of fuel ram~ 233 has a contour which varies in distance from the arc described by the radial extremity o the fuel arm as it pivots on air valve shaft 1~3. - This varying .
contour varies the gap between the ramp and the end of the fuel arm, causing the ball 241 to reciproca~ ln ~ore 244 and meter varying quantities of fuel through the bore 244, bore 23~ bore 107, conduit 108, and groove ox manifold 16~, varying the c~uan-tity of fuel discharged through orifices 16~ as shown in ~igures 10 and 11.
The fuel mixes with induction air indicated by arrow 246 in Figure 11 and rushes pa5t throttle 30 to the carburetor outlet (not shown). As throttle 30 is moved by linXage connected to an accelerator or other control means, the throttle vari.es the metering suction exerted on the underside of air valve 76. Thls causes the air valve tc open and close against the action of the biasing means 80 as described above, Thi5 in turn xotates the shaft 103 and fuel arm 239, thereby varying the quantity o~
fuel which is introduced into the carburetor induction passage by the air valve ~eans~ -' - ' ' - ' ~

~ 36 -34~

Figure 12 illustrates the desireable feature o~ sus-pending fuel ramp 233 from air valve shaft 103 by hanger ~34.
When hanger 234 .is laterally spaced from induction passage wall 93 by spacing 247, it facilitates keeping the hanger and fuel arm 239 at the same temperature. F~r reasons explained ~bove this tends to promote more accurate metering of fuel-. Figure ~2 also illustrates the above described ga~ 276 between the end of fuel arm 239 and upper con~oured surface of ~uel xamp 233.
Figure 13 is a partial enlargement and section o~
Figure 12 showing fuel ramp 233, the lower end of hanger 234, the lower end 267 of fuel arm 239 and bore 244. In the lo~er ~ :
end of bore 244 is an enlarged bore 269. The transition bet~een bores 2k4 and 269 is a shoulder 268 against which rests one end of the sprin~ 240. The opposite end o~ the spring hears on ball 241.. A plurality of grooves 273 are cut throu~h the lateral surface of the fuel arm adjacent an equatorial portion of ball 241.
. As shown in Figure 14, the ~rooves 273 are cut in such a manner as to extend from the outer surface of the fuel arm through the wall thereof so as to open into the bore 269. Several fuel arm wall segments 275 are left in place. These segments pro-vide attachment between the re~ainder of the fuel arm and a disc of material 274 which remains below segments 275. Disc 274 retains the ball against lateral movement relative to the vertical axis of enlarged bore 26g. If ball 241 has a very small clearance from the inner walls of enlarged bore 269, such as for instance the minimum clearance required to ~ermit reciprocation o the ball, it is then desireable that the total cross-sectional area o~ the intersections between grooves 273 and bores 269 be sufficient to pass the amount of fuel required for ~ull throttle operationD

. - 37 -. . .

p c ;

It should be note~ tllat the ~rooves 273 may be replaced by other kinds of structure capable of providing a path to bring fuel from the exterior of the arm to a metering edge adjacent an equatorial portion of ball 241 withi.n the fuel arm. This function can be performed not only by the a~ertures resembling grooves as d~pictea in the figures, but also by apertures of differing shape.
Moreover, if the walls of the fuel arm are suEficiently thick, the apertures may pene-tra~e the end of the arm instead of extend-ing through the peripheral surface thereof~ In such case t~e requisite apertures can penetrate the end of the fuel arm.
Figure 15 illustrates a-prior art fuel al~n ~h.ich may be used with the invention, instead of the ball-equipped fuel arm described above. Fuel arm 278 of Figure 15 includes an internal bore 279 and a lower end 280 adapted to traverse the upper surface 282 of fuel ramp 281. A gap 283 is present between fuel arm lower end 2~0 and fuel ramp u~pex surface 282. The flow of fuel across the ramp upper surface 282 and under ~he lower ~end of the fuel arm into bore ~79 is represented by arrows 28S.
The rate of flow is governed b~ a number of varia~les i.ncluding the cross~sectional area available for flow~ Since the ramp surface is designed to be close enough to the end o~ the fuel arm so that the cross-sectional area available for fuel flow is less than the~cross-sectional area of bore 279 (at least at idle and low power), the available cross-sect.ional area, indicated by dotted outline 284, will then be a function of the diameter "d"
of the fuel arm bore 279 and the height "h" of gap 283, accord- :
ing to the equation: A = 3.14dh.
In conventional fuel arms and ramps such as are depicted in ~iguxe 15, gap 283 may be measured in thousandths or ten- -thousandths of an inch at iale Accurate fuel meter;.ng is quite important for many inter~al combustion engine apPlications, and .

, ' Ll C

srnall inaccuracies in the li~t or contour of the ra~p can very substantially imp~ir fuel metering accuracy In practice it has been found that deviatiOns of as little as two-ten thousandths of an inch from design tolerances can be troubleso~e. The effect of such devi~tions on the available cross-sectional ~rea for the f1QW Of fuel can be calculated accordin~ to the formula yiven in the preceding paragraph, by substituting "y", the devia~ion in ramp contour, for l'h". Then~ the equation becomes A = 3.14dy When a ball is provided in the fuel arm in accor~ance wi-th one preferred embodiment of the present invention, the avail-able cross-sectional area for fuel flow is rendered considerably less sensitive to deviations in ramp contour This is illustrated in part by Fiyure 16, which is a much enlarged sectional view taken on section line 16-16 of Figure 13 r with the spring 269 omitted. The view shows the positions of the rarnp 233 and ball 241 relative to the extreme lower end of fuel arm 239.
~ ssume ~or purposes of discussion that the parts are in the positions as shown, and deviate from ~anufactur;ng specifi-cations. More specifically, let us assume that the dot~ed line 290 re~resents the intended position of the fuel ramp upper surface relative to the end of arm 23g. ~hen, ~Iy~ ~ay he consider-ed to represent the deviation from the ramp contour specification~
As indicated previously, the e~uation A ~ 3.14dy will provide the error in flow area and fuel metering accuracy or a ~rior art fuel arm. However, with the improved ar~ ~nd ram combination shown in Figure 16, it oan be shown that the err~r in cross-sec-tional area resultin~ fro~ a given value o~ "~", is less than 3.14ay.
In the improved fuel arm of Figure 16 there are meterin~
edges 292 formed by the in~ersections of ~ore 269 and grooves 273. Metering of fuel takes place between met~ring edge 292 and the closes~ ~oint of baLl 241 representea by arrow 293 Because .
i - ~ _ 3~ _ ~ ~ ~ c~ ~

the surface of the ball moves obliq~ely relative to meterin~
edge 292, a given devia-tion "y" will ~roduce ~ relatively smaller change in the distance between ~etering edge 292 and the opposing portion 293 of ball 241. This relatlvely smaller change in spacing between the ball and metering edge results in a rela-tively smaller amount of error in the cross-secti.onal area available for metering fuel. .
The foregoing is illustrated by the ~raph in ~i~ure 17, '~
which compares the error in flow area produced in the arm/ramp .
combination of Fiyures 15 and 16 with varying amounts of ramp deviation "y". In each case it i-s assume~ that the bore of the fuel arm .is 0.125 inches. In the gra~h,-ramD deviation "y" is expressed in inches x 103 in a range from 0 to 26. The error in flow area is expressed in square inches x 10 in a range from 0 to 100. Where, for instance, the deviation "y" is 8, the error in flow area of the conventional sys~em may be more than six times as great as that of the improved meterin5 system. Thus, the present invention considerably redwces ~he sensitivity of the fuel arrn/ramp combination to ramp contour tolerances There-fore, one can obtain quite acceptable fuel rnetering accuracy with less stringent ramp contour ~olerances. Alternately, one can obtain more accurate fuel meterln~ ~ith the improve~ents of the present invention as co~pared to conventional arrn~ra~p fuel metering systems, assuming both are manufactured to the sam~
tolerances.
Figure 18 discloses details o~ the preferred system for controlling the level of fuel in the float cha~bers. The igure shows first and second floats 248 and 249 sus~ended in ~:
float chambers 127 and 128 by first and second ~loa~ hangers 250 and 251. These hangers both include saddle portion~ 252 and 253 respectivelY~ which extend over the upper eage of fuel chamb~:r dividing wall 126. When the fuel chamber cover is astene~ on, ' . -.40 -- . . ' c ~46 i~s lower ~urface tigh-tly clamps the saddle members agains~ the dividing wall. The construction of the first and secon~ hangers and connected valving mechanism is identical; thus only the first hanger is ~ully shown in the drawings.
As shown in Figure 18, 10at hanger 250 includes a hinge 254 from which is suspen~ed a floa-t arm 255, including an upwardly extending float mount ~56. A pivot 257 at the end of float arm 255 is connected with valve actuating lever 258, which in turn engages valve member 25~ The latter cooperateS
with a valve seat 260 which is normally threaded into the threaded inlet 125 in fuel chamber front wall 121 and includes a threaded end to which may be secured a fuel line 261 A similar arran~e--ment of parts is provided in float chamber 128 to connect with a second fuel line 262.
The floats may be of any suitable material, such as for instance an expanded closed cell synthetic resin. The floats and float valves operate in a con~entional manner maintaining an aaequate level of fuel which may be aeli~ered to the air valve means by fuel arms 239.
Figure 19 discloses details of preferred embodiments of the thr~ttles. A portion of the carburetor bod~ 51 is sho~n to include a groove 300 runnin~ generally parallel to the axis of rotation of throttle shaft 105. This groove contains a seal 3~2 which contacts arcuate lo~er surface 32 of throttle 3Q in such a manner as to prevent leakage o~ air from a position ad~acent the carburetor body bottom surace 301 into the induction passage.
When the throttle ends 304 are flat and perpendicular to the axis of rotation of shaft 105, as is preferred, the seal 302 can include integral extensions 303 whlch continue up both en~s 34 of each throttle. Such extensions may for exa~ple extena to a position adjacent throttle shaft 105 Such an extension 303 :' ' .

"` :il~G46J

may also be seen in Figure 4 beneath shaft 115 in end wall 92, and in Figure 20.
As shown in Figure 19, the preferrea throttles 30 both include lips 40 at the intersections of their up~er and'lower sur- !
faces 31 and 32 These lips are formed by undercu~s 304 in the lower sur~aces 32 so that the extremities of the lips are sub-stantially on the projec-ted arcs of the lower sur~aces. ~en the ~hrottle lips have rounded upper edges 305, as vie~ed in ~ransverse ~ .
cross-section, this tends to reduce or eliminate pulsation and turbulence in the intake charge as it passes the e~ge o the throttle.
Figure 20 shows that the throttles 30 may include depressions 309 to receive the protrudi.n~ lower wall 192 and side walls o~ depressions 153 on the air valves (see air valve 75 in Figure 8) when the air valves and throttles are in the fully :
open position.
The throttles of Figure 20 are mounted on the ~hrottle shafts 105 and 115 of Figure 4, having throtkle.shaft extension 106 and 116 respectively. In order to provide counter-rotation of the throttles a~out said shafts, the sha~t extens.ions are fitted with levers and a reversing link. These include a bell -crank 310 which is installed on throttle shaft extension 116.
The ~ell crank has a lower arm 311, which may for instance be connected to acceleratox pedal linkage, a central bore 312 to receive the throttle shaft extension 116~ an upper arm 313 and a pivot 314 in the upper arm~ The lever 315 has a bore 318 to receive the throttle sha~t extension 106, ana an arm 319 having pivot 317 at its outer end. Reversing link 315 has its ends connected to pivots 314 and 317. Arrows in Flgure 20 illustrate movement o~ bell crank lower arm 311 to the ri~ht~ which causes the throttle sha~ts to turn in opposite directions, opening the $hrottle. . ... -Figure 21 illustrates a fuel ellrichment system which useable for starting purposes~ It includes a fuel enrichment port 325 in flow divider 77 (see E`igure 10) in the induction passaye of the c~rburetor. This port is in communication through passage 324 ~ith a valve 322 which is capable of placins the port 325 in communicatiOn with a vent 323 ~as shown) or, on ro~ation of the valve, with a conduit 321 extending to any suitable source oE
fuel 320, such as for instance one of the float chambers o~ the carburetor. A more detailed embodiment of the foregoing is dis-closed in Figure 22~
The fuel enric~nent system shown in Figure 22 includes the flow divider 77 and elements of the-carburetor ~ody end wall 93 and ~loat chamber 128 whose 100r 231 is partly visible. Fuel -enrichment port 325 in divider 77 is connected via ~assageway 324 in the divider and passageway 326 in wall 93 with a pocke~
327 forme~ at the end of fuel enrichmen~ valve bore 62 (see Figure 3). The transition between bore 62 and the smaller diameter pocket 327 forms a shoulaer 328 perpendicular to the bore a~is~
Within bore 62 is a vent port 3~9 which is shown in dotted outline. Facing vent port 329 across bore 62 is a simi-lar~ shaped port 332 referred to as the fuel port~ Vent port 329 is connected by a short conduit 323 to an openin~ 330 in free communication with the gas space 331 above the li~uid level in float chamber 127, fuel chamber dividing wall 126 (see Figure 18) having been omitted from Figure 22 to expose the conduit 334, described below.
Fuel port 322 communicates with a conduit 334 which ex-tends into the fuel in float chamber 128. The bottom end 335 of pipe 334 is spaced a short distance above the float chamber floor 231 in order that fuel may be drawn into conduit 334.
The fuel enrichment valve body 63 includes a cylindrical barrel portion 338 which is designed to fit snugly into bore 62 with its open end 33g engaging the shoulder 328, In the peri-pheral surface of the barrel are a first port 340 and a second por~ 341 (Figure 23) which are held in registry with vent port 329 an~ fuel port 332 respectively. Valve b~dy 63 also includes an enlarged casing section 342 externally threaded to receive a centrall~ apertured axial retainer nut 343.
Nut 343 retains hollow valve member 344 whic~ includes an oriice 346 at its otherwise closea inner end 345. In the peripheral wall portions of hollow valve ~ember 344 are the irst and second ports 347 and 348 (Figure 23i which are selectively brought into registry with ports 340 and 341 when an extension ;
351 on valve member 344 is turned by actuating lever 3~2~ An enlarged boss 349 thereon maintains the axial position ~ valve member 344. Threads 350 within boss 349 engage the head of needle valve 353. The needle val~e shank 354 extends through ~alve member 344 past the ports 347 and 348 so that ~ts point or valving sur~ace 355 is presented to ori~ice 346. Howe~er, the shank 354 is of an appropriate diameter to provide an annular space 356 between the shank and that inner surface of ~alve member 344.~
; When the fuel enrichment valve is in the position shown in Figure 22 the valve is open to t~e ~as space 331~
Suction applied by engine vacuum at the port 325 araws air and/or fuel vapors through opening 330, conduit 323, port5 32g, 340 a~d - 347, annu~ar passage 356, oriice 346, pocket 327r passages 326 and 324 and port 325 into the induction air passage. Rotation of actuator 352 60 clockwise rotates ports 340 and 347 out of registry, disconnecting fuel enrichment port 325 from gas space 331. Simultaneously, the ports 341 and 348 are broush~ into registryD Accordingly, suction applied a~ ~uel enric~men~
port 325 then araws fuel from floak chamber 1~8 through conduit 334, ports 332, 341 and 348, annular space 356, orifice 346, pocket 327~ passages 326 and 324 and port 325 into the induction passage o~ the carburetor. The delivery o~ enrich~ent fuel will .
- 4~ -~i c~

continue until the actUatOr 35~ is returned to the position shown in the drawings.
The needle valve 353 may be adjusted with a screwdriver inserted in the open ena o~ hollow extension 351. I~ the needle valve 353 is of synthetic resinous material, having a significantly ~reater coefficient of expansion than the valve member 344, it can provide a measure of automatic temperature com~ensation~ Since the needle valve will expand more than valve member 34~ as the tempera-ture rises, the needle valve will approach closer to orifice 346, thllS reducing the amount of enrichment ~uel supplied at high.er temperatures. ~:
. While various preferred embodiments of the inventi.on have been aisclosed above, it will be appre.ciated that many variations.can be made without departing rom the spirit of the following claims.

.

. . -- .

. - 45 ~

Claims (97)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A carburetor comprising: an induction passage having upstream air valve means and downstream throttle means therein, defining a fuel discharge zone therebetween, said throttle means being mounted on shaft means extending along a side or sides of said induction passage, and said throttle means including an upper surface portion which projects from said shaft means towards the opposite side of said induction passage and is inclined downstream;
a plurality of fuel discharge orifices positioned at the surface of said air valve means for communicating with said zone; biasing means for biasing said air valve means toward a normally closed position and for positioning said air valve means at varying positions between its open and closed positions in response to respectively greater and lesser flows of air through said air valve means; and fuel metering means in communication with said discharge orifices and operable to deliver respectively greater and lesser quantities of fuel to said discharge orifices in res-ponse to opening and closing of said air valve means.

2. A carburetor according to claim 1, wherein said fuel discharge orifices are in an edge of said air valve means.

3. A carburetor according to claim 2 including a manifold within the body of said air valve means extending along and ad-jacent said edge in communication between said metering means and said fuel discharge orifices.

4. A carburetor according to claim 1 wherein said air valve means is a member formed in at least two layers,at least a portion of the cross-section of said fuel discharge orifices being formed in an inward surface portion of one of said layers.

5. A carburetor according to claim 1, wherein said air valve means is a member formed in at least two layers, duct means being formed in an inward surface portion of at least one of said layers for conducting fuel between said fuel metering means and fuel discharge orifices.

6. A carburetor according to claim 3, wherein said air valve means is a member formed in at least two layers, at least a portion of the cross-section of said manifold being formed in an inward surface portion of one of said layers.

7. A carburetor according to claim 1, wherein said air valve means is a member formed from at least two layers of syn-thetic resinous material, at least a portion of the cross-sectional outline of duct means being formed in an inward surface portion of at least one of said layers.

8. A carburetor according to claim 7, wherein said member is mounted for rotation on a shaft having a fuel passage therein and said conduit is connected with said passage.

9. A carburetor according to claim 1, wherein said air valve means includes backfire relief apertures extending from its downstream surface through its body to its upstream surface, and a flexible flap member extending over said apertures on said upstream surface and adapted to lift free of said aperture on backfiring of said engine.

10. A carburetor according to claim 9, wherein said apertures are in the form of slots having a length to width ratio of at least about 2 to 1 and a width of up to about 6 mm.

11. A carburetor according to claim 9, wherein said fuel outlets are in one edge of said air valve means and said flap member is secured to an opposite edge of said air valve means by a clamp or clip member having a substantially "C"
cross-section.

12. A carburetor according to claim 9, wherein the upstream surface of said air valve means is curved as viewed in cross-section perpendicular to its axis of rotation and said flap is molded to a shape which conforms to the contour of said curve.

13. A carburetor according to claim 2 including a plura-lity of small grooves distributed at spaced intervals across said edge and extending generally in the direction of air flow past said air valve means.

14. A carburetor according to claim 2 including a groove in the upstream surface of the air valve means adjacent said edge and extending relatively perpendicular to the direction of air flow across said edge.

15. A carburetor according to claim 1 wherein said biasing means extends from the upper surface of said air valve means.
to a support above the air valve means.

16. A carburetor according to claim 15 including a pivot on the air valve means for connection to said biasing means, said pivot being moveable between two vertical planes as said air valve means moves from closed to open position.

17. A carburetor according to claim 16 wherein said support includes a moveable member having a moveable overhead pivot connected to said biasing means, said pivot being mounted and positioned for up and down movement in the space between said vertical planes.

18. A carburetor according to claim 17 wherein said moveable member is a reciprocable member mounted for reciproca-tion on a vertical post extending above the air valve means.

19. A carburetor according to claim 17 wherein said biasing means includes a tension rod connected between the pivot on the air valve means and the moveable over head pivot, the overhead pivot being positioned laterally for causing said tension rod to swing from an inclination to one side of vertical, through vertical, to an opposite inclination relative to the vertical as the air valve means swings from closed to open position.

20. A carburetor according to claim 19 wherein said moveable member is a reciprocable member mounted for reciproca-tion on a vertical post extending above the air valve means.

21. A carburetor according to claim 1 wherein said biasing means includes spring means connected directly or indirectly between said air valve means and a support above said air valve means.

22. A carburetor according to claim 1 including an air valve positioner moveable between a first position for holding the air valve means slightly open and a second position for more fully closing said air valve means.

23. A carburetor according to claim 1 comprising an air valve positioner including a withdrawable obstruction member moveable between a first location in which it obstructs closing of the air valve means beyond idle position and a second location to which the obstructing member is withdrawn so that the air valve means can be more fully closed by the biasing means.

24. A carburetor according to claim 23 wherein the obstructing means is positioned to obstruct the air valve means indirectly by contacting the biasing means, thus preventing the biasing means from closing the air valve means further than idle position.

25. A carburetor according to claim 23 comprising means for moving the obstructing member, which means includes a spring for normally biasing the obstructing member to its non-obstruct-ing position, a diaphragm vacuum motor for moving the obstructing member into obstructing position and a conduit providing communi-cation between the disphragm and an area of reduced pressure in the carburetor throat.

26. A carburetor according to claim 1 wherein the fuel metering means includes a fuel pick-up arm and metering ramp.

27. A carburetor according to claim 26 wherein said fuel metering means includes a fuel chamber and said air valve means is supported for rotation upon a hollow shaft which extends through a wall of the fuel discharge zone to said fuel chamber, said fuel pick-up arm being secured to said hollow shaft within said fuel chamber, and said fuel arm including a hollow bore which has an inlet at one end of said arm adjacent said ramp and which is in communication through said hollow shaft with the fuel discharge orifices on the air valve means.

28. A carburetor according to claim 26 wherein said fuel pick-up arm includes a bore having at one end thereof an inlet adjacent said ramp, said inlet including a metering edge, ball valve means in said one end of said bore, means for main taining said ball valve means in contact with said ramp and means for laterally confining said ball during movement of said arm relative to said ramp, whereby fuel may be metered by movement of the ball relative to said metering edge.

29. A carburetor according to claim 28 wherein said metering edge is formed by the intersection of said bore and apertures formed in wall means defining said pick-up arm.

30. A carburetor according to claim 29 wherein said apertures extend through the peripheral surface of said wall means to said bore.

31. A carburetor according to claim 26 wherein said fuel pick-up arm is mounted on a shaft, said metering ramp is supported by hangar means, and said hangar means is carried on and suspended from said shaft,

32. A carburetor according to claim 26 wherein said fuel metering means includes a fuel chamber, a common wall divides said fuel chamber from said fuel discharge zone and said metering ramp is supported by hanger means spaced inwardly in the fuel chamber from said wall, whereby liquid fuel can circulate in said chamber between the wall and the hangar means.

33. A carburetor according to claim 26 wherein said metering ramp is supported by hanger means, and said fuel pick-up arm has a higher coefficient of expansion than the hangar means.

34. A carburetor according to claim 1 comprising a fuel enrichment system including a source of fuel, a fuel enrichment port in the fuel discharge zone and a valve con-trolled conduit extending from said source to said port.

35. A carburetor according to claim 34 wherein said fuel metering system includes a fuel chamber, valve and float means in said chamber for controlling the level of fuel therein and a fuel pick-up arm and metering ramp for metering fuel to said fuel discharge zone, said fuel chamber being said source of fuel for said fuel enrichment system.

36. A carburetor according to claim 34 wherein a flow divider is positioned in said fuel discharge zone and said fuel enrichment port is in said flow divider.

37. A carburetor according to claim 34 wherein said valve controlled conduit includes a valve in series with the source of fuel and the fuel enrichment port to regulate the flow of fuel to said port.

38. A carburetor according to claim 34 wherein said valve controlled conduit includes a needle valve and throttling orifice in series with the source of fuel and the fuel enrichment port to regulate the flow of fuel to said port.

39. A carburetor according to claim 38 wherein the needle valve is mounted in a hollow member, said throttling orifice being formed in one end of said hollow member.

40. A carburetor according to claim 39 wherein said needle valve has a significantly greater coefficient of expan-sion than said hollow member, whereby said needle valve and throttling orifice are temperature responsive for automatically decreasing the available amount of enrichments at increased temperatures.

41. A carburetor according to claim 34 wherein said valve controlled conduit includes an on-off valve and a needle valve and throttling orifice in series with the source of fuel and the fuel enrichment port to regulate the flow of fuel to said port.

42. A carburetor according to claim 41 wherein said on-off valve and needle valve are both in a hollow member, said throttling orifice being formed in one end of said hollow member.

43. A carburetor according to claim 42 wherein said needle valve has a significantly greater coefficient of expansion than said hollow member, whereby said needle valve and throttling orifice are temperature responsive for automatically decreasing the available amount of enrichment at increased temperatures.

44. A carburetor according to claim 42 wherein said hollow member is a cylindrical member.

45. A carburetor according to claim 44 wherein said hollow cylindrical member is rotatable about its longitudinal axis in a bore formed in the body of said carburetor, and said on-off valve comprises port means in the wall of said cylindrical member, said port means being moveable by rotation of said cylindrical member.

46. A carburetor according to claim 34 wherein said valve controlled conduit includes valve means for selectively connecting said fuel enrichment port with said source of fuel or a vent.

47. A carburetor according to claim 46 including a fuel chamber for containing a supply of fuel with a gas space above said fuel, and said vent is a passage communicating between said valve means and said gas space.

48. A carburetor according to claim 1 wherein the throttle means upper surface, when viewed in vertical cross section in the throttle closed position, has sufficient inclina-tion to prevent accumulation and dumping of fuel.

49. A carburetor according to claim 1 wherein said throttle means has a lower surface portion which is arcuate when viewed in vertical cross section, a substantial portion of said lower surface portion being at a uniform radial distance from the axis of rotation of the throttle means.

50. A carburetor according to claim 49 including a carburetor body which encloses said throttle means, sealing means being positioned between said lower surface portion and an adjoin-ing portion of said body.

51. A carburetor according to claim 50 having a molded carburetor body including groove means formed in said body adjacent said lower surface portion, said sealing means being positioned and held in said groove means in sealing engagement with said lower surface portion.

52. A carburetor according to claim 1 wherein said throttle means has parallel ends which are perpendicular to its axis of rotation.

53. A carburetor according to claim 52 including a carburetor body which encloses said throttle means, sealing means being positioned between the ends of said throttle means and adjoining portions of said body.

54. A carburetor according to claim 53 having a molded carburetor body including groove means formed in said body adja-cent the ends of said throttle means, said sealing means being positioned and held in said groove means in sealing engagement with said ends.

55. A carburetor according to claim 1 wherein said throttle means has a lower surface portion which is arcuate when viewed in vertical cross section, a substantial portion of said lower surface portion being at a uniform radial distance from the axis of rotation of the throttle means, said throttle means also having parallel ends which are perpendicular to its axis of rotation.

56. A carburetor according to claim 55 including a carburetor body which encloses said throttle means, sealing means being positioned between said lower surface portion and an adjoining portion of said body, and between the ends of said throttle means and an adjoining portion of said body.

57. A carburetor according to claim 56 having a molded carburetor body including groove means formed in said body adjacent the ends of said throttle means and adjacent said lower surface portion, said sealing means being positioned and held in said groove means in sealing engagement with said ends and with said lower surface portion.

58. A carburetor according to claim 57 wherein said sealing means is a continuous sealing member disposed in seal-ing engagement with said ends, lower surface portion and carburetor body.

59. A carburetor according to claim 1 wherein said throttle means has a lower surface portion which is arcuate when viewed in vertical cross-section, a substantial portion of said lower surface portion being at a uniform radial dis-tance from the axis of rotation of the throttle means, a back surface portion, and parallel ends which are perpendicular to said axis of rotation.

60. A carburetor according to claim 59 having an open back, said back surface portion being recessed in and surrounded by said lower surface portion and ends.

61. A carburetor according to claim 60 wherein said throttle means is a throttle member formed from synthetic resin.

62. A carburetor according to claim 59 wherein said back surface portion has an area approximately equal to that of the upper surface portion.

63. A carburetor according to claim 59 having communica-tion between said back surface and said induction passage.

64. A carburetor according to claim 1 wherein said throttle means includes an arcuate lower surface portion which meets with said upper surface portion along an edge past which air flows through said fuel discharge zone, said throttle means also including a lip extending along said edge for disen-gaging fuel from the throttle member so that it does not flow down the arcuate lower surface portion.

65. A carburetor according to claim 64 wherein said lip comprises an interruption of the lower surface portion.

66. A carburetor according to claim 64 wherein said lower surface portion is undercut beneath said ?ip.

67. A carburetor according to claim 64 wherein said lip has an outer tip which is substantially on or within the projected arc of the lower surface portion for balancing forces which would otherwise tend to open the throttle means spon-taneously.

68. A carburetor according to claim 64 wherein the upper edge of the lip is curved for reducing noise by reducing or eliminat-ing pulsation and turbulence in the intake charge as it passes the edge of the throttle means.

69. A carburetor according to claim 1 wherein said air valve means and throttle means are each mounted on separate shafts and, referring to a vertical reference line in the approxi-mate center of the region through which the induction air flows with the air valve means and throttle means in the full open position, the shaft for the air valve means is at a greater hori-zontal distance from said reference line than the shaft for the throttle means.

70. A carburetor according to claim 69 wherein the biasing means includes a vertically reciprocating hanger and swing-ing tension rods connected with said air valve means and said hanger.

71. A carburetor according to claim 69 wherein said air valve means, when viewed in side elevation, has a curved or bent shape for reaching across the throttle shaft and down into the fuel discharge zone when the air valve means and throttle means are open.

72. A carburetor according to claim 69 wherein the throttle means is a throttle member having an upper surface portion and the length of the air valve means is sufficient to overlap a portion of said upper surface portion when said air valve means and throttle means areopen.

73. A carburetor according to claim 71 wherein the throttle means is a throttle member having an upper surface portion, and the length and bend or curvature of the air valve means are sufficient for causing said air valve means to assume a position against said upper surface portion when the throttle means and air valve means are wide open.

74. A carburetor according to claim 1 wherein said air valve means includes upper and lower surfaces extending from a boss, at which the air valve means is mounted for rota-tion on shaft means, to a tip of said air valve means which is moveable in an arc as said air valve means rotates on said shaft, said throttle means includes upper and lower surface portions, at least the upper surface portion of which extends from a boss, at which the throttle means is mounted for rotation on shaft means, said bosses being secured in said carburetor with a clearance between them, said clearance being sufficiently small to direct the main flow of air around the tip of the air valve means, rather than between the bosses, but of sufficient size to cause some air to pass between the bosses and over the upper surface portion of the throttle means to purge fuel from said upper surface portion.

75. A carburetor according to claim 74 where a sealing member is positioned on one of said bosses extending generally parallel to the axis of rotation and positioned for engaging the opposing boss when the throttle means and air valve means are closed and for disengaging therefrom on rotation of the throttle means or air valve means to open position.

76. A carburetor according to claim 1 wherein the air valve means is a single air valve member.

77. A carburetor according to claim 1 wherein the air valve means is a plurality of air valve members.

78. A carburetor according to claim 1 wherein the throttle means is a single throttle member.

79. A carburetor according to claim 1 wherein the throttle means is a plurality of throttle members.

80. A carburetor according to claim 77 including means for substantially synchronizing the movements of the air valve members.

81. A carburetor according to claim 79 including means for substantially synchronizing the movements of the throttle members.

82. A carburetor according to claim 80 wherein the biasing means is the means for synchronizing the movements of the air valve members.

83. A carburetor according to claim 82 wherein said biasing means includes a moveable member to which each of said air valve members is connected for movement in unison with one another.

84. A carburetor according to claim 81 wherein the means for synchronizing the movements of the throttle members comprises a rotation-reversing lever linkage, said linkage including a first lever arm connected with a first shaft-mounted throttle member, a second lever arm connected with a second shaft-mounted throttle member and a connecting link connected between said levers and positioned for rotating the second throttle member in the opposite direction when the first throttle member is rotated in a given direction.

85. A carburetor according to claim 77 wherein each air valve member is mounted for pivotal movement on its own individual shaft.

86. A carburetor according to claim 79 wherein each throttle member is mounted for pivotal movement on its own individual shaft.

87. A carburetor according to claim 85 wherein the shafts on the respective air valve members are located at the edges of or outside an imaginary envelope formed by projecting upwardly the outline of the induction passage outlet.

88. A carburetor according to claim 86 wherein the shafts of the respective throttle members are located at the edges of or outside an imaginary envelope formed by projecting upwardly the outline of the induction passage outlet.

89. A carburetor according to claim 1 wherein the air valve means and throttle means respectively are a plurality of air valve members and a plurality of throttle members, each throttle member and each air valve member being mounted for pivotal movement on its own individual shaft, said shaft being located at the edges of or outside an imaginary envelope formed by projecting upwardly the outline of the inducation passage out-let.

90. A carburetor according to claim 1 including an induction passage which is sub-divided by a vertical dividing member into two adjoining throats.

91. A carburetor according to claim 90 wherein the air valve means comprises an air valve member for each of said throats.

92. A carburetor according to claim 90 wherein said throttle means comprises a throttle member for each of said throats.

93. A carburetor according to claim 90 wherein said air valve means and throttle means include air valve members and throttle members for each of said throats.

94. A carburetor according to claim 92 wherein the throttle valve members have tips which, when viewed in closed position, extend beneath and closely adjacent the lower edge of the divider.

95. A carburetor according to claim 93 wherein the throttle valve members have tips which, when viewed in closed position, extend beneath and closely adjacent the lower edge of the divider.

96. A carburetor according to claim 91 wherein said fuel metering means includes separate fuel metering means for each of said air valve members.

97. A carburetor according to claim 1 including an induction passage divided into a plurality of throats and having a plurality of air valve members with separate fuel metering means connected thereto, said separate fuel metering means being connected with sources of supply for different fuels.