US2752131A - Carburetors - Google Patents

Description

.une 26, 1956 G. J. GRETZ CARBURETORS Filed Dec. 17, 1952 22a 19a 9 Q2 Fig.

United States Patent .CARBURETGRS VGeorge LGretLPittsburgh, Pa.

Application December 17, 1952, Serial No. 326,495

4 Claims. (Cl..261-'-23) My invention relates to carburetors, and yparticularly to down draft carhuretors of the plain tubetype.

It is well -known that the present day plain tube types tof Vdown draft carburetors in Vcommon use provide a compromise -between the best Vwide open throttle power at 'slow speeds and Athefhighest speed under level road driving conditions, economy Vand maximum power being sacrificed for speed.

'One object of my present invention is to provide an improved down .draft carburetor ofthe plain tube type providing better performancezat all speeds without saericing economy in full consumption.

Another object of my invention is .to provide a down draftcarburetor of the type described in .which there is no -after drip when the-.car on'which it isinstalled is brought to a sudden-stop or isstopped on agrade.

Another object .of .my invention-is .to provide an improved carburetor of the type described which will furnish a longer Yrange of ,smoother voff idle performance without any so-called flat spots.

Another object of my inventionis to provide acarburetor of the type described having .a constant and more uniform 'distribution of fuel at all engine speeds or throttle positions.

Another object of my invention is to provide 'a carburetor of the type described -having -two separate Venturi openings, one of which becomes effective ,to'provide additional fuel'mixture in response to high engine velocity when the throttle is open.

A further object of myv invention is to V.provide acarburetor in which the Venturi `.openings are in removable sleeves and-in which the goriiices which 'discharge fuel vinto the Venturi passages are inaremovablemember, whereby .by substituting different sleeves -and dilerenti members the Ydisposed respectively inmain-,and ,auxiliary Venturi openings. The oat chamber which'is formed aspart of the central body section is semi-circular and has .its ycenter located at substantially the verticaljportions of thefuel channels. The fuel `level vis 4maintained k,no zhigher `than the upper -ends :of the vertical portions of `the fuel .channels 'and as a Vresult fuel'will not .run out or drip .when

V the car is brought toa sudden stop V,or stopped :on a

grade.

The fuel mixture .at ,idlingspeeds is supplied through alow speed circuit comprising .a first vertical vvpassageway Vwhich communicates at its upper ,'en'd with the horizontalportionrof the main fuel channel .and at its lower .end with arst discharge port containing the idling adjustment screw. A branch-passageway connects this yfirst `verticalpassageway with Va second port-which'is so lo- 2,752,13 Patented .Jurre l26, 1956 ICC cated with respect to the throttle `that when the throttle is closed no fuel is discharged through this port, but as the throttle opens the second portis gradually opened to the air stream to cause it to discharge fuel into the air stream in parallel with the first port, this second port being effective Ato provide the proper fuel mixture for speeds between idling speeds and a predetermined low yspeed such for example as 22 miles per hour. VIt should be noted that at closed throttle the main discharge port and the second port meter air into the low speed idling system.

The low speed idling system also includes a `second vertical passageway communicating at its upper end with the horizontal portion of the main fuel channel and at its lower end with a third discharge port disposed above Vthe second port. An airbleed passageway connects both vertical passageways between theepoint of connection with the horizontal portion of the main fuel channel directly with the main discharge port. As the throttle is gradually-opened the second port is gradually transformed from an air bleed port to a fuel discharge port, and as the suction continues to increase the third discharge port starts to discharge additional fuel into the air stream. This continues to a predetermined speed such, for example, as 45 milesrper hour under level road driving conditions. As the throttle continues to open, the main discharge port is gradually transformed from an air bleed into a fuel discharge port.

The carburetor also includes .a second Venturi opening in parallel with the Inain Venturi opening. This second `opening isnormally closed at `its'lower end by a buttery valve biasedto its closed position by a spiral spring connected to the accelerator pump operating link in such ,manner that as the throttle is opened the spring tension is gradually decreased. A'portion of this butterfly valve extends into the main air strearnso that as the velocity of the air suction increases, it will produce an increasing force tending to open .this valve. Fuel is ,supplied to this lsecond Venturi opening by an auxiliary discharge port connected to the horizontal portion of the auxiliary fuel channel. The parts `are so `proportioned that at the higher engine speeds, such, for example, as 6() or more miles per hour-under level road driving conditions, -if `the throttle is open so Vthatthe tension on the ispring biasing the butterfly valve :to its closed position is reduced, this valve will open Yand will thus cause the aux- Viliary -discharge port to discharge fuel into the second Venturi opening. This Yauxiliary Venturi opening enables the main Venturi opening Vto be reduced ,in size and thus obtain -betterfuel economy at the usual driving ,speeds and also betterpower at slow speed wide open throttle conditions, without sacrificing vacceleration or power at the higher driving speeds.

My .carburetor further includes va novel buffer mecharusm for Ycontrolling .the movement .of the .throttle to its -fully closed position when the throttle is suddenly Vreleased to enable vthe .car to be brought to .a sudden stop without stalling the motor. This buffer mechanism is so constructed that it will regulate the rate of closing of Vthe throttle in thelastfew degrees ofits movement to its closed position .to a .Value which will prevent stalling.

Other objectsand characteristic features of my invention will become apparent Vas the .description proceeds. I `shall .describe one lform of .carburetor embodying my invention, and shall then point out .the novel .fea-

tures thereof in claims.

In the accompanying drawings, Fig. 1 is a side elevational view of a carburetor embodying my invention with .a l portion broken away and `in section to show the Aaccelerating pump.

tFig. V2 Vis a Ysectional'view taken on the line Ill-II of Fig. `l.

Fig. 3 is a sectional view taken on the line III-III of Fig. 2.

Fig. 4 is a sectional View taken on the line IV-IV of Fig. 2.

Figs. 5 and 6 are detail vertical sectional views of the Venturi tubes and 11 forming part of the carburetor shown in Figs. 1, 2 and 3.

Fig. 7 is a detail vertical sectional view of a member 24 which houses the main and auxiliary fuel channels for the carburetor shown in Figs. l, 2 and 3.

Fig. 8 is a vertical sectional view of a modified arrangement of the Venturi tubes and member 24 for the carburetor shown'in Figs. 1, 2 and 3.

Fig. 9 is a detail sectional View taken on the line IV-IV of Fig. 2.

Similar reference characters refer to similar parts in each of the several views.

Referring now to the drawings, the carburetor in the form here shown comprises three sections 1, 2 and 3 separated by suitable gaskets 4 and 5 and bolted together in the usual manner by bolts 6 and 7. The various sections may be constructed in any suitable manner, but will usually consist of die castings as is customary.

The upper section 1 contains the air inlet 8 which is divided by a partition 9 into two separate passageways 8a and 8b leading into main and auxiliary Venturi openings lta and 11a formed in Venturi sleeves 10 and 11 disposed in the main body portion 2 of the carburetor. The upper section 1 also houses a choke valve'12 so disposed that when it is moved to its closed position it will close or restrict the passageway 8a.

The Venturi openings '10a and 11a communicat through passageways 13a and 13b with the induction passage 14 of the carburetor. The induction passage 14 is located in the lower or throttle body 3 of the carburetor, and cooperates with a throttle valve 15 mounted on a throttle valve shaft 16 journaled in the throttle body 3.

As will appear 'more fully hereinafter, fuel is at times discharged into the main Venturi opening 10a at the throat of the opening through main discharge ports 17 which communicate with a fuel well 18 through a main fuel channel 19 and a main fuel metering jet 20, while fuel is at times discharged into the auxiliary Venturi opening 11a at the .throat of the opening through auxiliary discharge ports 21 which communicate with the fuel well 18 through an auxiliary fuel channel 22 and an auxiliary metering jet 23. VThe fuel channels 19 and 22 are disposed in a transversely extending member 24 which tits with a snug t into suitable openings formed in the upper part of the main body portion 2 in such manner that this member can be readily removed to enable the fuel metering jets to be cleaned, or removed and replaced with jets of dilferent sizes to permit the carburetor to be readily adapted to different engines having different fuel requirements.

The Venturi sleeves 11 and 12 are also readily movable so that these sleeves can be changed to adapt the carburetor to different engine requirements, and these sleeves and the transverse member 24 may either be made in separate parts, as shown in Figs. 5, 6 and 7, or they may all be made in one piece as shown in Fig. 8, since cach different size of Venturi opening will ordinarily require a dierent size jet.

The fuel well 18 communicates through passageways 25 and 26 with a fuel barrel or float chamber 27 provided with atfuel inlet valve 28'and a float mechanism 29 for controlling the flow of fuel into the float chamber 27. The float chamber 27 is formed as part of the central body section 2 and has its center located as close as Vpossible to the vertical portions 19b and 22b of the fuel channels 19 and 22, that is at the center of the fuel well 18.V The float mechanism is adjusted to maintain the -fuel level no higher, and preferably slightly lower, than the upper ends of the Vertical portions 19h and 22b of 4 the fuel channels, and as a result since the center of the fuel in the fuel well is located substantially at the center of the fuel in the oat chamber, fuel will not run out of the main and auxiliary fuel discharge ports when the engine is at rest regardless of the angle at which the carburetor is tilted. Likewise, fuel will not run out or drip when the car is brought to a sudden stop or is stopped on a grade.

The fuel mixture at idling and low speeds is supplied through a low speed circuit comprising a first vertical passageway 3G which communicates at its upper end with the horizontal portion 19a of the main fuel channel 19, and at its lower end with a low speed discharge port 31 provided with an idling adjusting screw 32. A branch passageway 30a connects this first vertical passageway 36 with a second discharge port 33 which is so located with respect to the throttle valve that when the throttle valve is closed no fuel will be discharged through this port, and this port will function as an air bleed because it is above the throttle valve. However, as the throttle valve is opened, this second port is gradually exposed to the air stream in parallel with the port 31. It should be pointed out that when the throttle valve is closed, air is sucked in through the main discharge ports 17 into the horizontal portion 19a of the main fuel channel where it mixes with fuel sucked through the vertical portion 19b of the main fuel channel 19. The emulsion thus Vformed is sucked down through the passageway 30 and discharged into the induction passage 14 through the low speed discharge port 31. The idling adjusting screw is adjusted to give the desired idling speed of the engine. As the second port 33 becomes exposed to the air stream fuel is also discharged into the air stream through this port in parallel with the port 31, this second port being effective to provide the proper fuel mixture for speeds between idling speed and a predetermined low speed such, for example, as 22 miles per hour.

The low speed idling system also includes a second vertical passageway 34 communicating at its upper end with the horizontal portion 19a of the main fuel channel 19 and at its lower end with a third discharge port 35' opening into the induction passage 14 above the second port 33. An air bleed passageway 35a connects both Vertical passageways 30 and 34 of the low speed system intermediate their ends directly with the main discharge ports 17. As the throttle is opened wider the second port 33 is gradually transformed from an air bleed port to a fuel discharge port, and as the suction continues to increase the third port 35 starts to discharge additional fuel into the air stream. This action continues to a predetermined speed such, for example, as 45 miles per hour under level road driving conditions. At still higher speeds, the main discharge ports 17 are gradually transformed from an air bleed into fuel discharge ports.

The carburetor includes an accelerating pump P located at one side of thecentral body portion 2. The accelerating pump is connected to the shaft of the throttle valve vin a manner which will be made clear presently, and is effective at each sudden opening of the throttle valve to discharge a jet of fuel into the main Venturi opening 10a.

The pump P is provided with two concentrically arranged plungers 42-and 43 respectively mounted ina cylinder A47 formed in the main body portion 2. The cylinder 47 terminates at its lower end in a concentric cylinder 48,

having a diameterwhich is just large enough to receive Y the main plunger 42,-and the cylinder 48, in turn, is connected through a passageway 49 and a check valve 50 with the oat chamber 27. It will be obvious that each time the plungers are moved to their upper positions, as shown,

the cylinders 47 and 48 will both fillup with gasoline.

arreglar .of the rod 57 is 'connected' by means of a link '59 toatsegment 60 secured to the shaft 16 whichactuates the throttle valve.

The auxiliary plunger A3 surrounds and slides on the -main plunger 42, and is provided at-its upper-end with an inwardly extending annular flange v45 which tits theplunger rod 44 with a sliding t. A vcoil spring 48 surrounds the plunger rod 144 between vthe plunger 43 and the ,cross mem- -ber 56 and biases-theauxiliary plunger to the position in which the ange 45 engages the top of thevmain plunger. This spring acts whenlthe-throttle-valve-is opened to maintain the two plungers ,42and'43 to the'relative positions shown.

Upo-n up strokes ofthe pump caused Yby closing of the throttle, fuel ows into the cylinders 47 and 48 ,from the oat chamber 27 through the check valve 50 and passageway 49, while uponeach quick down stroke of the main plunger 42 which occurs each time the throttle valve is opened quickly, fuel is discharged by the main plunger through a duct or channel 46 to an outlet orifice or jet 53 disposed in the main Venturi opening a. The duct or channel .46 is provided .with a non-return valve more or less diagrammatically shownat 54. The main plunger 42 is provided-with a longitudinally extending groove 5S which is slightly longer than the cylinder 48. This groove has a two fold purpose. 'When the throttle valve is opened slowly, the main plunger .42 will move down slowly and while some fuel will be expelled from jet 53, part of the fuel in the cylinder y49 will pass up through this groove V55 into cylinder47 from whichit .will later be expelled by the supplementalplunger 43 through said groove and through jet-5,3 by .way of. duct or;passage .46.

Upon a quickdownwardV movement of the main plunger which occurs uponeach vquick opening of the throttle, a larger amount oftfuel will be discharged-through jet 53 by the main plunger than would Vbe discharged on a slow opening of the throttle and the fuel trapped in cylinder 46 below piston 43 will belgradually-expelled Vfrom this cylinder by way of groove S5 and duct 53. The supplemental piston acts as a follow up piston and prolongs the period during which the accelerating discharge takes place.

VIt will be seen, therefore, that the accelerating `pump operates in synchronism with the-throttle valve and-functions so as to provide a supply of accelerating fuel at the times and in the amounts needed.

The auxiliary Venturi opening 11a is provided for the purpose of providing a richer fuel mixture at the higher engine speeds to provide good high speed performance without sacricingfuel economy at the lower engine speeds. The passageway 13b which connects the air inlet 8 with the induction passage 14 through the auxiliary Venturi opening 11a is normally closed at its lower end by a buttery valve 61 mounted on a horizontal shaft 62 journaled in the main body portion 2 of the carburetor. The shaft 62 projects out through the sidewall of the main body portion 2, and is provided at its outer end with a spiral spring 63, one end of which is secured to the shaft 62 and the other end of which is secured to the link 59 which actuates the accelerator pump in such manner that the valve is biased to its closed position by a force which will decrease as the throttle valve is opened. The buttery valve 61 is made somewhat wider than the lower end of the passageway 13b to provide a portion 61a which projects into the passageway 13a where it is subjected to the velocity of the air stream passing through the passageway 13a. The parts are so proportioned that at the lower engine speeds the biasing force exerted by the spring 63 will maintain the valve 61 closed. However, at the higher engine speeds, such for example, as 60 or more miles per hour under level road driving conditions, if the throttle is opened far enough so that the tension exerted by the F spring 63 is reduced, the velocity of the air stream acting on the portion 61a of the valve will exert a force on the valve which is suicient to open it, and the auxiliary discharge ports 21 then become effective to discharge additional fuel into the Venturi opening 11a and hence with positions.

.the bore 66 below the piston 65.

the'induction passage 14, thus providing aricher yfuel mix- -turetogive good engine performance atthe higher lengine speeds.

The ycarburetor further includes means-for controlling the Ymovement of the throttle toits fully vclosed position when the accelerator pedal is suddenly released to .enable -the car to be brought to a sudden stopiwithout stalling :the motor. 65 slidably mounted in a bore 66 connected bya-passage- .way 67 with the oat chamber 27. The piston 65 .is

As here shown, this means comprises afpiston formed on the lower end of a piston rod 68, the upper fend of which is connected by arm 69 to a .verticalfactu- .ating rod '7G slidably supported in a guideway 71. The -rod 76 is operatively connected at its lower ,end lto the `throttle .valve shaft i6 by a lost motion connection including a Y'tl-shaped link 72 pivotally attached atone yside to the lower end of the'rod 70 and slidably mounted at the other side in an arcuate slot 73a formed in a seg- .ment .73 secured to the .throttle valve'shaft 16. The piston is counterbored at 65a to slidably receiveaplunger 74 secured at its lower end to the valve body 2. The

.plunger .74 is provided with a vertical passageway 75 which is connected at its lower end with the passageway respect to the plunger 74.

As shown in Fig. 4, the ports are in their closed throttle As the throttle is opened, the resulting movement of :the segment 73 removes any downward 'force frorn the lower end of the rod 70 and hence from the ypiston rod 6S,.antl as a result the spring 77 which is under .compression in theclosed throttle position forces `the piston .65 .upwardly and causes gasoline to be sucked into 'I'he spring is so proportioned that if the throttle is opened far enough it will .force the piston 65 upwardly to a position in which .the

plunger 7.4 is completely withdrawn from vthe counterbore Y65a permitting the bore 65u to become completely `filled .with gasoline. `the throttle is fullyopened the piston y65 will be moved :tto-the upper end of the cylinder by engagement ofthe The slot 73a is so proportioned that .when

link 72 with the right-hand end of the slot 73a as viewed in Fig. 4. When, however, the throttle is permitted to close, the slot 73a permits the throttle to close quickly until the throttle is approximately two-thirds closed whereupon the link 72 will then engage the left-hand end of the slot 73a, as viewed in Fig. 4, and cause the piston 65 to move downwardly to a position in which the plunger 74 starts to enter the counterbore 65a. When this happens the gasoline which is then present in the bore 66 is expelled at a rate which depends upon the size of the opening 76 and this opening is made suiciently small to regulate the rate of closing of the throttle in its last few degrees of movement toward its closed position to a value which will prevent stalling.

One advantage of a carburetor embodying my invention is that since for each throttle opening or closing all air bleed ports serve also as fuel ports there is no clogging -of the ports by carbon, whereby one of the common troubles of present day carburetor is eliminated.

Another advantage of a carburetor embodying my invention is that it is simple in construction and therefore economical to manufacture.

Another advantage of a carburetor embodying my invention is that it provides good performance under all operating conditions and at the same time provides good fuel economy.

Although l have herein shown and described only one form of carburetor embodying my invention, it is understood that various changes and modifications may be vmade therein YWithin the scope of the appended claims without departing from the spirit and scope of my invention.

`Having thus described my invention, what I claim is: 1. In a carburetor having a single air inlet connected through main and auxiliary venturi openings with a single induction passage, main and auxiliary fuel discharge ports disposed in said main and auxiliary venturi Vopenings respectively, a single throttle valve disposed in said induction passage, a second valve having a closed position in which it prevents the ow of air through said auxiliary venturi opening and an open position in which it permits the flow of air vthrough said auxiliary venturi opening, said second valve being biased to a closed position by a force which is responsive to the throttle valve position and which decreases as the throttle valve is opened and having a portion which projects into the air Vstream passing through said main venturi opening for opening said second valve when the velocity of the air passing through said main venturi opening exceeds a predetermined velocity.

2. In a carburetor having a single air inlet connected through main and auxiliary venturi openings with a single induction passage, main and auxiliary fuel discharge ports disposed in said main and auxiliary venturi openings respectively, a single throttle valve disposed in said induction passage, a second valve having a closed position in which it prevents the ilow of air through said auxiliary venturi opening and an open position in which it permits the flow of air through said auxiliary venturi opening, said second valve being biased to a closed position by a force which is responsive to the throttle valve position and which decreases as the throttle valve is opened and having a portion which projects into the air stream passing through said main venturi opening for opening said second valve when the throttle Vis opened more than a predetermined amount and the velocity of the air passing through said main venturi opening exceeds a predetermined velocity.

3. In a carburetor having a single air inlet and a single induction passage connected through main and auxiliary venturi openings, means for discharging fuel into said venturi openings to provide a fuel mixture, a throttle valve in said induction passage, and a second valve disposed at the lower end of said auxiliary venturi opening f8 and normally biased to a closed position by a spring connected to said throttle valve, said second valve having a portion extending into the air stream through said'main venturi opening for opening said second valve to provide additional fuel mixture in response to high engine velocity when the throttle is open.

4. In a carburetor having a single air inlet and a single induction passage connected through main and auxiliary venturi openings, means for discharging metered amounts of fuel into said venturi openings inproportion to the velocity of the air stream passing therethrough, a throttle valve in said induction passage, and means responsive to the throttle valve position for preventing the passage of air through said auxiliary venturi opening except when said throttle valve is opened more than a predetermined amount and the velocity of the air stream exceeds a predetermined velocity, said means comprising a buttery valve effective when closed to prevent the flow of air through said auxiliary venturi opening and biased to its closed position by a force which decreases as the throttle valve is opened and having a portionV projecting into the air stream through said main venturi opening in such manner that the air stream in said main venturi opening will exert a force on said butterfly valve in opposition to said biasing force tending to open said buttery valve.

References Cited in the file of this patent UNITED STATES PATENTS 1,929,266 Viel Oct. 3, 1933 1,963,458 Beard June 19, 1934 2,019,172 Chandler Oct. 29, 1935 2,033,396 Perrine Mar. 10, 1936 2,087,293 Olson July 20, 1937 2,144,153 Henning Ian. 17, 1939 2,215,683 Wirth Sept. 24, 1940 2,315,183 Bicknell et al Mar. 30, 1943 2,376,732 Strebinger May 22, 1945 2,399,079 Udale Apr. 23, 1946 2,422,751 Schneider lune 24, 1947 2,452,698 Strebinger Nov. 2, 1948 2,568,987 Brunner Sept. 25, 1951 2,621,030 Henning Dec. 9, 1952 2,621,911 Lindsteadt Dec. 16, 1952 2,628,085 Rauen Feb. 10, 1953

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