CA2189651C - Carburetor - Google Patents

Abstract

A carburetor of the slide (14) and metering rod (50) type comprising an air flow straightening device (92) at the inlet position (14) thereof for straightening and accelerating the air flow in narrow channels from the inlet end to the metering rod (50) to thereby reduce turbulence at the metering rod.

Description

W0 95133g2~ ~ 2 1 8 9 6 5 I PcrnJsg~6428 rl~T TlTTTlRTl~T~
BPck~round of the Invention The present invention relates to a carburetor of the slide and metering rod type, and more particularly to an assembly for straigtening air flow arranged within the carburetor throat to enhance the flow of air from the carburetor inlet around the metering rod in order to reduce t~rh~ n~e and increase air velocity at the fuel outlet by compressing the aLr ~low. This provides more precise fuel control and an optimum air~fuel ratio for more power with fuel conservation.
Brief DescriDtion of the Prlo~ ~rt Carburetors of the slide and metering rod type are well-known in the patented prior art, as evidenced by the inventor's prior U.S. Pat. Nos. 3,985,839; 4,013,741;
4,442,046 and Re. 31,475.
As disclosed in the aforementioned reissue patent, for example, these carburetors include a body having air inlet and outlet ends and a throat ~t~n~in~ there-between. A throttle slide member is slidably mounted on the body within the throat, and a tapered metering rod or needle is connected with the slide member and extends r~ ..llW~L lly into a fuel supply tube connected with a ~uel res~rvGir mounted beneath the body. The slide member h- s ~ront and rear substantially flat panels disposed in substantially paral' el relation. The metering rod is provided with a downwardly and inwardly tapered rear ~lat ~ace and is mounted for longitudinal ad~ustment relative to the slide member.
One drawback of the afoL~ i rlnr~ carburetor is that the f low of air through the throat includes a great deal of turbulence at the metering rod and across the outlet of the fuel supply tube. This turbulence results SUBSTITUTE SHEET (RULE 26) W0951D922 ~ 218~65~ PcrlUsg4106428 in an uneven draw of fuel from the fuel supply tube, thereby producing an inconsistent air~fuel mixture within the carburetor.
The present invention was developed in order to overcome this and other dL ' ~rkq of the prior slide and metering rod type carburetors by providing an assembly for strA;rintpn~n~ air flow within the carburetor throat to reduce turbulence and increase air velocity by compressing the air f low to the metering rod.
Summarv of the Invention Accordingly, it is a primary object of the present lnYention to provide a carburetor inrl~ in~ a body having an air inlet end, an air outlet end, and a throat ~rtPn~i; ns between the inlet and outlet ends . A fuel supply tube is connected with the body and has an outlet - - i r~ting with the throat . A throttle slide member is moYably mounted within the body int~ te the inlet ~nd outlet end6 for tLd,.~v~.~e movement across the throat to vary an unblocked portion thereof. A device for 2~ straightening air flow is arranged in the throat at the lnlet portion for reducing t~lrh~ nce and increasing air velocity by compressing the air flow to the metering rod.
The air str~i~htpn;n~device comprises a cross-type elongated insert extending substantially from the inlet end to the slide member. The cross-type insert defines narrow elongated channels for the air flow from the inlet end to the metering rod. The air f low channels 2re defined by elongated panels secured to each other in substantially perpendicular relation. In one embodiment, the panels in one plane of the insert are substantially aligned with the metering rod. In another ~ L, the panels are positioned out of ;l l i; with the metering rod for a purpose to be described hereinafter.

SU~STITUTE Sl IEFT (~ULE 26J
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21~9657 3rief DescriDtion o~ the Drawincs Other objects and advantages of the invention will become apparent from a study of the following spe -i f i CAt~ n when viewed in the light of the n: ~~ ying drawings, in which:
Fig. 1 is a side elevation21 view in section of carburetor including the air straightening device according to a first o~; L of the invention;
Fig. 2 is a sectional view of the carburetor taken along line 2-2 of Fig. l;
Fig. 3 is a perspective view of the throttle slide member at the carburetor;
Fig. 4 i8 a per6pective view of the insert of the carburetor of the pre6ent invention;
Fig. 5 i8 el l~ront elevational view of the inlet portion of the carburetor, showing the first ~
of the air strA;~ht~n;ng device of the present invention;
and Fig. 6 is a view similar to Fig. 5, showing a second F ' ~~ ~rL. of the air straightening device of the present invention.
DetA; 1 ed Descriotion Referring to Fig. 1, the carburetor 10 of the present invention generally comprises a body 12 having an air inlet end 14, an air outlet end 16 and a centrally located slide supporting portion 18; a cover 20 adapted to fit over the upper portion of the slide supporting portion 18; and a fuel reservoir or bowl 22 secured to the underside of the body beneath the slide 3-:pporting portion 18. Preferably, the inlet end 14, outlet end 16 And slide supporting portion 18 are formed of unitary construction, and a throat 24 extends through the body from one end to the other. ~he cover 20 and reservolr 22 may be removably secured to the body 12 in any suitable SUeSTiTUTE Sl IE'T ~ULE 26) wo ss~33~ ~ 2 1 8 9 6 5 1 -- Pcr~sg~06428 mr~nner, such as by ~lexible a~d resilient spring members, not shown.
As sperifir~lly shown in Figs. 1, 2, and 4, the body 12 i9 provided with an insert 26 fixedly mounted by ~ locking screw or the like within the slide supporting portion 18. The insert 26 comprises an upper yoke portion 28 having an aperture 30 therethrough that c~,LL~ ...ds in size and shape to the adjacent portions of the throat 24 in the body 12. The upper end of the upper insert yoke portion 28 is open and comprises oblique end ~aces 32, one of whlch has a threaded aperture 34 ~Yt~ ; nr therethrough which is adapted to receive the locking screw in a conventional manner. A fuel supply tube 36 is secured to the bottom of the upper portion 28 and extends through an aperture thereln into - n;cation with the aperture 30. The fuel supply tube 36 extends downwardly into the fuel reserYoir or bowl 22 and is provided at its lower, end with an outwardly and downwardly extending flange or "umbrella" portion 38 dispo6ed near the lower end of t~e bowl 22 for a purpose to be more fully described hereinafter.
As shown in Fig. 2, the insert 26 is narrower than the adjacent portlons of the slide 6upporting portion 18 80 as to define groove6 on each 6ide of the slide supporting portion that are adapted to slidably receive the side edge portions of the front and rear panels 40 and 42 of a throttle 61ide member 44 mounted within the slide supporting portion 18 for substantially vertical slidable movement therein as 6hown in Fig. 1. At it6 upper potion, the 61ide member 44 is provided with a pair of downwardly facing oblique 6urfaces which are adapted to engage the _ l Lary oblique faces 32 on the upper end of the insert 26 for the pl~rpose of limiting the downward movement of the slidé member 44 within the slide supporting portion 18 of the body 12. The locking screw SUBSTlTiJItSH.EI iRULE''~j W095/33922 ~ 2 1 8 965 ~ -- Pcr~ss4/o6428 c~Ln be adjusted to engage one of the oblique surf~ces on the slide member 44 for the purpose of adjustinq the lowest position o~ the slide member. ~n 2ddition to the locking screw, the insert 26 may be retained within the slide supporting portion 18 by locking pins or the like, not shown.
A fuel metering rod or needle 50 is adjustably secured to and extends downwardly from the slide member 44, through the fuel supply tube 36 and into the flange portion 38 thereof disposed near the bottom of the reservoir or bowl 22. The metering rod 50 i5 provided wlth an enlarged head portion 52 at its upper end which is slidably received within a bore 54 in the slide member 44. As shown in Fig. l, the bore 54 preferably is near or at the front panel 40 of the throttle slide member 44 for a purpose to be described hereinafter. The head portion 52 is provided with a key portion 56 that is receivable within a complementary groove 58 in the slide member bore 54 for the purpose of maint2ining the metering rod 50 in a desired orientation which will be more fully described hereinafter. A coil spring 60 or other biasing means is provided between the bottom of the slide member bore 54 and the lower surface of the head portion 52 of the metering rod 50 and serves to urge the head portion 52 upwardly away from the lower end of the bore 54, as sper; f; r~ 11 y shown in Fig. l .
An ad~ustinq screw 62 is threadably mounted within an upper threaded portion of the slide member bore 54 and has a lower end in engagement with the upper surface of the enlarged head portion 52 of the metering rod 50. The adjusting screw 62 is provided with a lower internal bore 64 and an upper internal bore 66 which are separated by an '~nt~ tP flange portiol~ 68 having an aperture therethrough ~rtlrnri;ng between the lower bore 64 and the upper bore 66. A control cable 70 for the throttle slide SUBS I ~TUTE SHE'cT (RULE 2~;

Wo 95133922 ~ 2 1 8 9 6 5 1 PCTNS94~06428 member 44 extends through the upper bore 66 in the ~d~u6ting screw 62 and through th~ aperture in the ~nt. ~Ate flange 68. The control cable 70 15 provided with an enlarged head portion ~2 at its lower end which i8 disposed within the lower bore 64 in the adjusting screw 62 and through the aperture in the intermediate ~lange 68. The control cable 70 is provided with an enlarged head portion 72 at its lower end which is disposed within the lower bore 64 in the adjusting screw 62 and is in ~n~a, t with the int~ t.e flange 68 for- the purpose o~ connecting the cable 70 to the adju6ting screw 62 and to the throttle slide member 44.
A helic21 spring 74 surrounds the cable 70 and tends from the lower end of the upper bore 66 and the adjusting lS screw 62 to the upper end of the slide supporting portion 18. At its upper end, the helical spring 74 surrounds the lower end of a tube 76 oYto~linq downwardly from and threadably secured in an aperture in the cover 20 for the slide supporting portion 18. The cable 70 extends through the tube 76 and the cap member 20 for con~ection to any suitable type of manual control means disposed on the vehicle in which the carburetor is mounted. The helical spring 74 serves to urge the slide member 44 to the closed or down position shown in Fig. 1 wherein it cuts off air flow through the throat 24 of the body 12.
Upward v~ ~ of the cable 70 serves to move the slide member 44 upwardly against the force of the spring 74 to allow air flow through the throat 24 and upward movement of fuel from the reservoir 22 through the fuel supply tube 36 in a manner to be de6cribed more fully hereinaf ter .
The ve-tical position of the metering rod or needle 50 relative to the slide member 44 may be easily adjusted by rotation of the adjusti~g screw 62 which is provided at its upper end with a tra~sverse recess 78 or the like SU~STITUTE SHEET (RULE 26) W0 95133922 ~ JS94~06428 ~ 21 89651 for receiYing the head of a screwdriver or sLmilar tool.
Rotation of the ad~usting screw 62 serves to move the head portion 52 of the metering rod 50 upwardly or downwardly within the lower portion of the bore 54 in the - 5 throttle slide member 44.
The metering rod or needle 50 is provided with a downwardly and inwardly tapered flat portion 80 P~t~r~li from the upper portion toward the lower end thereof. The key portion 56 is 80 located on the enlarged head portion 52 of the metering rod 50 that the flat portion 80 faces the outlet end 16 of the carburetor body 12 when the metering rod S0 is mounted within the throttle slide member 44, as sperifi~lly 6hown in Fig. 2. It will be readily seen, therefore, that upward movement of the slide member 44 and LoLL~ollding upward movement of the metering rod 50 within the fuel supply tube 36 will cause a gradually larger opening at the outlet of the fuel supply tube for the supply of fuel from the fuel reservoir or bowl 22 to the carburetor throat 24, owing to the tapered flat portion 80 on the metering rod. By varying the taper of the flat portion 80 on the metering rod 50, the variation in fuel flow for a given upward movement of the slide mem~er 44 and metering rod 50 may be 2djusted.
~s shown in Figs. 1 and 2, the inner surface of the carburetor body 12 is tapered inwardly from the inlet end 14 to the slide supporting portion 18 and is tapered outwardly from the slide supporting portion 18 to the outlet end 16, thereby creating a Venturi effect when air flows through the carburetor throat from the inlet to the outlet end. This air flow past the metering rod 50 and outlet end of the fuel supply tube 36 serves to create A
vacuum at the outlet of the fuel supply tube, thereby causing a flow of fuel from the fuel reservoir or bowl 22 upwardly through the opening in the fuel supply tube SUBSTITU I E Sh tT (I~ULE 2~) W0 95133922 ~ ~.lIU~ Y

defined by the meterins rod 50 and into the carburetor throat 24 where the fuel is mixed with incoming air and moves toward the outlet end therewith. The fuel flows upwardly from the fuel reservoir 22 into the fuel supply tube 36 because the reservoir 22 is vented to the ~tmosphere in a manner to be more fully described hereinafter .
The fuel reservoir bowl 22 is provided with a suitable 10at valve assembly 82 or any other suitable means for maintaining a minimum quantity of fuel in the reservoir. The f loat valve assembly 82 is co~mected to a fuel supply tube in any suitable manner.
The downwardly extending flange portion 38 on the lower end of the fuel supply tube 36 serves to trap fuel within it and to keep air from entering the fuel supply tube when the carburetor is subjected to vibration owing to travel of the vehicle over rough terrain or the like.
sy trapping fuel within it, the flange portion 38 also serves to reduce turbulence in the fuel entering the lower e~d of the fuel supply tube. A smooth supply of fuel to the lower end of the fuel supply tube 36 is further enhanced by the upwardly and inwardly tapered inner surfaces 86 of the flange portion 38 which lead to the lower end of t~e fuel supply tube.
It will be appreciated that upward and downward movement of the throttle slide ~ember 44, as actuated by the control cable 70 or other suitable means, serves to control the air flow from the inlet end to the outlet end of the carburetor body 12 and also serves to control the flow of fuel from the fuel reservoir or bowl 22 to the carburetor throat 24 because of corr~spn~ n~ upward or downward ~ of the metering rod 50 secured to the throttle slide member 44. A ~irinifir~nt feature of the carburetor is to ac~elerate and straig~ten air 10w past the metering rod to assure thorough atomization and SU9STITU I ~ S~ T (.ri~.'LE ~Cj W095133922 ~~ 2 1 8 9 6 5 ~ r~ r~
distribution of the f uel in the airstream bef ore it reaches the combustion chamber.
~ choke assembly 9o of any suitable construction is cllso provided which allows extra fuel to be atomized ~nd to enter the carburetor throat when desired. The choke ssembly is shown in Figs. 1 and 2 and is similar to that described i~ the i~ventor ' 8 prior U . S . Patent No . Re.
31 , 47S .
In arr~r~7Anr~ with the present i~vention, an air straightening device 92 is mounted in the throat at the inlet portion of the carburetor and pref erably extendY
substantially from the inlet end ~4 to the slide member 44. The air straightening device 92 preferably is of elongated cross-type construction and comprise6 panels 94 and 96 secured to each other in substantially perpendicular relation as shown in Figs. 1, 2 and 5. The panels 94, 96 serve to define narrow elongated channels 98 for the flow of incomi~g air from the inlet end 14 to the metering rod 50. In this manner, incoming air is straightened and accelerated in narrow paths in the channels 98 toward the metering rod 50, thereby reducing t~r~ n~-e at the metering rod and enabling the air/fuel mixture to be more precisely controlled for high perform-a~ce and economy operation.
For high performance operation, the air straighten-ing device 92 preferably is oriented in the manner shown in Fig. 5 wherein the upstanding panels 94 are in Al i, L with the metering rod 50 and the later211y nr~;ng panels are substantially perp~n~;;c~ r to the 3 0 metering rod .
For economy op~ration, the air straightening device 92 prefe_ably is oriented in the m~ner shown in Fig. 6 wherein the lower panels 94, 9 6 are at an angle of approximately forty-five degrees ~45) to the metering rod 50 to define a lower channel 98 aligned with the _g _ SU~STITU I E SHEE, (RULE rGj ~ ~ W095133922 ~18't~5 I Pcr~ss4/06428 ~. O
. , .
metering rod to thereby reduce the amount 0~ F~ir flow past the metering rod.
As an illustrative example, the thickness of the panels 94, 96 may be approximately one-twelfth of the width of the meteri~g rod.
The air straiyhte~ing device 92 may be constructed of any suitable material and may be mounted in the inlet end of the carburetor in any suitable manner. Also, the air str~i~ht~n;ng device 92 may be used with any type of slide a~d metering rod carburetor other than the embodi-ment e~ecifically disclosed herein.
While in accordance with the provisiorLs of the patent statute the preferred forms and embodiments of the invention haYe been illustrated and described, it will be apparent to those of ordinary skill in the art that various changes and modifications may be made without deviating from the inventive concepts set forth above.
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Claims (6)

What is claimed is:

1. A carburetor, comprising (a) a body having an air inlet end, an air outlet end, and a throat extending therethrough from said inlet end to said outlet end;
(b) a fuel supply tube connected with said body and having an outlet in communication with said throat;
(c) a throttle slide member movably mounted within said body intermediate said inlet and outlet ends thereof for substantially transverse movement across said throat to vary an unblocked portion thereof; and (d) a metering rod extending downwardly into said fuel supply tube to control the supply of fuel therethrough; and (e) elongated crossed-element air straightening means mounted in said throat and extending substantially from said inlet end to said slide member, said air straightening means being constructed to define a plurality of elongated channels to straighten and accelerate air flow from said inlet end to said metering rod, wherein said channels extend in substantially parallel relation from said inlet end to said metering rod.

2. The carburetor of claim 1 wherein said air straightening means is a cross-type insert having elongated panels secured to each other in substantially perpendicular relation and extending outwardly into engagement with the surrounding carburetor body defining said throat to define four of said elongated channels.

3. The carburetor of claim 2 wherein some of said elongated panels are upstanding and are aligned with said metering rod, and the other panels extend laterally and are substantially perpendicular thereto.

4. The carburetor of claim 2 wherein said panels are oriented such that two lower, adjacent panels are positioned on opposite sides of said metering rod.

5. The carburetor of claim 4 wherein each of said lower panels is disposed at an angle of approximately forty-five degrees (45°) to said metering rod to define a lower channel aligned with said metering rod.

6. The carburetor of claim 2 wherein the thickness of said elongated panels is approximately one-twelfth of the width of said metering rod.