US2194540A - Carburetor - Google Patents

Description

Mmh .26, 1940. A, BREEZE 2,194,540

CARBURETOR Filed March 18, 1937 5 Sheets-Sheet l f6 O @M2220 Yi@ -f' fav@ '/9 /4 f2 Y' @9K 5.9 l B 0 5 66 Ml# f ./a f f6 I i @Y 7% 2 f5 w" 4Z y .ZZ g 4%@ l 4f ik I. O/Z W v 62 jf Z 154 2j) l W7C? eoffe/Ef/eeze.

H I /MMJW March 26, 1940.

G. A. BREEZE 2,194,540

CARBURETOR Filled March 18, 1937 3 Sheets-Sheet 2 CARBURETOR Filed March 1s, 1937 s sheets-sheet s G. A. BREEZE 2,194,540 4 Patented Mar. 26, 1940 yFi'A'FElT OFFICE oARBURE'roR George A. Breeze, Waterford Township, Oakland County, Mich.

t Application March 18',

2' Claims.

This invention relates to an improved and automatically controlled air valve type of carburetor for-internal combustion engines.

It is an important object ofr this invention to provide an improved air valve type of carburetor wherein the mixture ratio is varied between that most suitable for maximum economy at different throttle settings and that developing the most power, the change over in either direction being automatically accomplished by means responsive to whether the air valve opens more or less than that opening normally corresponding to the existing throttle opening. It will be evident that if the air valve does not open to a point corresponding to the throttle setting, then the engine is laboring or working under full power as its speed of rotation is not sufficient to demand enough air to openthe air valve to the required extent. Under such circumstances, a richer or powerful mixture is called for to enable the engine to develop its maximum power at the given throttle opening, even if such opening is v only partial.

exceeds that normal to a given throttle opening, theincreased speed will cause an increased opening of the air valve, under which circumstances an ultra lean mixture isl automatically provided by the carburetor of this invention, thus economizing on fuel, reducing the overspeeding effect v and serving to scavenge the cylinders and reduce the carbon therein, withouty damage to the engine because under these circumstances the load is lighter. t

It is a further object of this invention to provide an improved air valve carburetor wherein the fuelmetering is under the coordinated controlof both the air valve and the throttle, either of` which can automatically dominate the metering control to provide either an economy or power. mixture ratio. y

It is also an object of this invention to provide ank air valve type of carburetor, wherein cams operated. separately by the air valve and throttle coact with a fuel metering pin control, the arrangement being such that the action of each cam on the metering control is subject to adjustment over the entire range, and the heels and toes of each cam are separately adjustable to vary the mixture control at the extremes With- Contrawise, when the engine speed 1937, Serial No.y 131,575 (Cl. 261-49) It is still another object of this invention to provider an improved .and simplied choke control for enrichening the mixture for starting purposes, the choke control being arranged to cooperate with both the air valve` and the fuel metering control to progressively increasethe spring load on the air valve, and to increase the fuel supply, as well as beingso coordinated with the air valve `that a rapid opening thereof will release the choke control.

Other and further objects of thisinvention will become apparent from the following disclosures., taken in. connection With the accompanying drawings, in which: Figure 1 is a top plan View of a carburetor embodying the features of this invention;

' Figure 2 is an elevation of the throttle lever or front side ofr thevcarburetor;

Figure 3 is an elevation of the throttle cam or rear side of the carburetor;

` Figure 4 is a. front central vertical section of the carburetor, with parts shown` in elevation, corresponding to the section line IV--IV- of Figure l;

Figure 5 is a section 4, showing the fuel. bowl and float mechanism;

Figure 6 is a'section on the line VI-'VI of Figure 2, showing the accelerator pump and dash pot construction; l

Figure '7 is a fragmentary detail section taken along. the line. VII--VII of Figure 1,. showing the choke or mixture enrichening control; and

Figure 8fk is a distorted diagrammatic outline layout of the cooperating air valve and throttle 'linkages controlling the fuel metering pin.

As shown on the drawings:

The improved air valve type. of carburetor of this invention has been shown as of the downdraft type in the accompanying drawings, al- 'though it will be evidentthat the invention is not limited to the illustratedV form. Thev carbn. the une v--v of Figure buretor, as illustrated, comprises three. members f through which. `the mixture passage continues. The uppermost member or casing H has anl external seat I2 to receive an air cleaner and is internally proled at i3 to cooperate with an air valve I4. It also provides bearings for a cross-shaft I5 carrying apower cam I5 at one end.

The center member I'I provides a continuation .IB of the mixture passage and has a projecting portion I9 which serves as a fuel chamber cover, the cover also providing a bearing for a metering control shaft 25. The air valve I4 is slidably mounted on a vertical guide 2l mounted in a bridge 22 across the mixture passage I8.

The lower member 23 contains a Venturi passage 24 forming a continuation of the mixture passage I8, a throttle shaft 25 being located in the lower portion of the Venturi passage adjacent a carburetor mountingflange 26. rlhe lower member 22 also embodies a fuel chamber 2 and an accelerating pump and dash pot chamber 28. The fuel chamber 2l contains a float 29 which actuates a fuel admission valve 35 controlling the entry of fuel from a source of supply 3i.

VThe'fuel chamber 2l' extends partly around the barrel of the lower member 23 in order to provide more reserve fuel and to place a fuel outlet passage 32 approximately centrally of the fuel volume, in order to maintain the normal fuel level at the passage 32, in spite of unusual inclinations of the carburetor as a whole. The passage 32 comprises a tube depending from the center member and communicating withl a passage 33 in the -bridge 22, from which a fuel spray nozzle 34 extends downwardly (in the case of a down draft carburetor) into the restricted zone of the Venturi passage 24. The fuel chamber also communicates through a passage 35 with the bottom of the dash pot and accelerator pump chamber 28, aball check valve 35 being provided at the bottom of the chamber 28 to prevent return flow of fuel.

The air valve I4 is slidably mounted on a guide 2l forming an extension of the fuel nozzle, the guide being passaged at'S'l to receive an air valve vspring 3i), the calibration of this spring in relation to the profile of thev passage I3 about. the air-valve being'such that as the air valve opens, the mixture tends to be progressively leaned byt the control mechanism to be hereinafter mentioned. In other words, the spring is purposely made lighter than would be required to maintain a uniform fuel and air ratio as the valve I4 opens. It will be evident in this connection that the chosen spring rate orstrength determines the depression range within the carburetor in response to engine suction, and the length of the spring controls the initial depression required to open the air valve. Control of the fuel supply to the nozzle 34 centersabout a metering pin 3S cooperating with a tapered section in the horizontal fuel passage 33.' The pin 39 is of cylindrical section with an external head 4I backed by a light spring 42 which retracts the pin, the controlled proximity of the pin to the taperedsection 45 metering the `flowof fuel to the nozzle 34. The pin 39 is operated by a bell ended lever 43 secured to the metering control shaft 2B which in turn is actuated by either the power cam I5 on the cross-shaft l5 or a throttle cam 44 on the throttle shaft 25.

' The cross-shaft l5 carrying the power cam I5 is actuated by a ball ended lever 45 slidable in a horizontal guide passage 46 in the air valve I4, so that an opening movement of the air valve causes counter-clockwise rotation `of the cross- 2,194,54o f f f shaft I5 in Figures 4 and 8. The powercam I 6 cooperates with a short armed lever 41 on vone end of the metering control shaft 2li, adjustment being provided by means of a set screw 48. Similarly, the throttle cam 44 cooperates by means of a rod 49 with a long armed lever 50 on the control shaft 2l), another set screw 48 providing for adjustment between the lever 59) and the rod 49. f

The cams l5 and 44 are somewhat similar in construction in that an adjustable spring face 5I is utilized, the center portion of which is in conv The power cam I6 limits the rise of the short lever 4l and thereby limits the opening movement of the metering pin. The opening ofthe f metering pin in relation to theope'ning of the air valve is4 thus controlled by the contour of the power cam throughout the power range. It is thus possible to provide varying fuel ratios for varying conditions over the entire speed range of an engine, as by'varying the lower end 54. of the cam for adequate pick up, and thevupper end for high speed operation, without affecting the central portion of the range, which latter is adjusted `by means of the screw 48 in the short lever 4l which modifies the whole range.

The throttle cam 44 provides a driving range mixture control'which provides a normally leaner mixture ratio than thepower cam I6, so that the cam 44, acting through the push rod 49 on the long lever 55, normally holds the'short lever 4'! out of contact or away froml the power cam I5. The throttle cam 44 has its spring face 5I calibrated for' best economy on a given engine and car load for constant speeds on a level road. A screw 55 on the end 5l' of the cam nearest the push rod 49, when the throttle is closed for idling, serves to provide the idling adjustment, which is made directlyoln the fuel through the metering pin 39, and blends smoothly into the higher speeds as-thethrottle is opened Without a transition point or spot, as when a conventional idling bypass is used. The adjusting screw 48 in the long lever 55 varies the mixture over the whole partial throttle opening range, while the idling adjustment screw 56 affects only the lowest or idlingspeeds The throttle position determines the metering pin location under normal conditions at any partial throttle opening, the air valve being free to open or close according to the air passing through the engine will run slower at a given throttle l openingr so that the air valve will not open as far, and the mixture will be correspondingly richer. If, however, the engine load is lighter and the engine-runs faster, as on a down-grade, or when the throttle ris closed for deceleration,

the air valve will open farther than the throttle.

position would demand normally andthe mixture will be leaner. This-lean mixture, characteristic when-the engine temporarily speeds up, tends to burn out carbon, and does-no harm to the engine because it doesnotoccur under load and is of short duration.

When the throttle is opened for acceleration, the power cam lf3 comes into play as the throttle cam 44 rotates far enough to drop the push rody 49k out of contact with the longlever 50, allowing the power cam to control the metering pinS through contact with the short lever v1W, so that coincident with the throttle opening the `mixture is enriched to that calibration chosenfor bestpower at the given speed as determined by the air valve opening andthe contour of the power cam I6.

if the throttle is openedy slowly venough sov that the air valve i4 does not jump, no extra accelera-Y` tion fuel is required, as a gradual opening of the air vaive supplies more fuel in step therewith, the ratio being determined by the power cam profile and the proleof the air valve and its profiled passage, the two profiles being preferably so laid out that the air valve travelwill be proportional to the increasing volume of Aair admitted past the valve in order to simplify the requirements of the profile of the cam I6.

The crossshaft i5 carries a lever 58 which operates a rod Eii carrying a piston Gil loosely tting'in the accelerating pump anddashhpot chamber 28, the arrangement bein-g such that a slow opening movement roi? the air valve will move the piston downwardly in the chamber at a speed slow enough to allow the fuel therein to bypass around vthe piston. On the other hand, a rapid downward movement of the l piston will apply pressure on the fuel there-- below, since the ball check dii will close the fuel passage Accelerating fuel is taken from the chamber Z through aport 5| in the wall considerably above the bottom of the piston stroke, thisy port leading to a' valve seat 62 controlled by a weighted valve which lifts in response to fuel pressure toailow fuel to be discharged through `a passage leading to an accelerating jet 65. rihe valve is ported at ii to commu-k nicate with the air above the fuel in the fuel chamber to kill any suction tending-to lift the valve t3. The travel of the valve t3 is limited hy the cover it after it has been yforced open far enough to shut off the air ports'li to prevent fuel from being discharged therethrough. Preferably, the valve G3 is a loose fit in its guide so that some of the fuel escapes around the sides f the valve, as such an. arrangement permits the use of a larger drill Vin the accelerator jet S which is proportioned to the acceleration requirements oi the engine on which the carburetor is to be used. ,v

If the throttle is opened suddenly, the air valve moves rapidly and the clearance around the piston til is insuicient'to allow fuel toy escape, causing delivery of accelerating fuel until the piston tl covers the port ill. 'Thereaften the piston serves only as a steadying dash pot by means of -a choke control which acts `to progressively add increasing spring 'tension opposing the opening of 4the air'valve'and to' retract the meteringpin 39 to also increase the fuelv ilow. This is accomplished by means of afchoke lever 66 adjustably. mounted on a' U-shaped bracket member ci which is pivoted on a stub shaft 68 between the cross shaft I5 and the metering control shaft 2@ as this mechanism acts on both.shafts... v

An initial slight movement oi the choke lever 5 brings the Ushaped bracket member t? into contact with one end t9 of'` ay torsion spring lil on the cross-shaft it, the other end 7l of the `spring engaging the accelerator lever 5i! so that continued clockwise movement oi' the bracket member t? in Figure 7 imposes additional spring load on the air valve ill. Simultaneously, a lug l2 on the bracket member 61 moves to contact a stop 3 carried by the metering shaft 20 in a direction Ito rotate the shaft and increase the opening the metering pin 3S. The bracket and spring `strength is such that the spring. will hold against cranking speed engine suction, but will allow the air valve to open when the engine starts, and if the motor is raced withthe choke on, the added force acting on the air valve tends to kick off .the choke, thus releasing the same and returning the carburetor to normal operating conditions.

Since the .cams 'It and it act on the long and short levers 5t and 4l to restrain opening movement of the metering pints, it is necessary, to

, provide the .foregoing choke operation, that the shaft it be movable relative to the levers. To this end, the two levers are mounted on a sleeve l'i rotatable on the shaft 2G, and a torsion spring` 4cams I6 and t,

For further eiiiciency in starting, a small aperture 'dll in the center of the air valve lll communicates through the tubular extension of the fuel nozzle ywith the nozzle 3ft proper. This air passage is small, and` at starting speeds the suction in the carburetor produces a high air velocity which eiects a good atomization of the lfuel entering` the nozzle, thus helping startin and minimizing crankcase dilution.

The profile vof the air passage i3 is 'very important, as air velocities controlled by the relative contours of the' air valve and passage walls are worked out to permit the use of lighter air valve springs and to obtain air valve travel and .power cam movement proportional to the volume of air flow. This air valve spring is worked out so light that if the air valve is opened by engine suction `without a corresponding increase in the metering pin opening, a leaner mixture results. This gives the carburetor its unique automatic mixture changing characteristics with partial throttle openings. At higher engine speeds, the lower side of the air valve rides on a very high velocity air stream and is thus prevented from snapping wide open because of th vusevof a slight spring. v

It will thus be seen that I have invented an improved air valve type of carburetor wherein the faults common to previous air valve carburetors have been eliminated by the use of an Ulv air valve arranged to move in proportion to the volume of air flowing therepast and opposed by a relatively light spring which provides a char acteristic tending to lean the mixture as the valve opens, in combination with a power cam operated by air valve movement to controllably increase the fuel flow, whereby when the engine operates at a higher speed than normal for a given throttle opening, as when the engine is lightly loaded, the mixture willbe leaned out, while when the engine is operating slower than normal, as when pulling hard for a given throttle opening, such as occurs during warm-up, acceleration and hill-climbing, the mixture will be automatically enrichened to a varying power mixture determined by an adjustable cam operated by the air valve. The carburetor of this invention thus provides an automatically adjustable mixture control providing maximum economy for normal operation and the maximum power obtainable from an enrichened mixture when operating conditions so require.

I am aware that many changes may be made and numerous details of construction may be varied through a wide range without departing from the principles of this invention, and I, therefore, do not purpose limiting the patent granted hereon otherwise than is necessitated by the prior art.

I claim:

l. In a carburetor of the air valve type, an air valve, spring means urging said air valve to closed position, a fuel supply reservoir, a nozzle in communication with said reservoir, fuel meteringrneans including a fuel valve, spring means urging said fuel valve to open position, a first cam connected with said air valve and oscillable by movement of said air valve, a first cam fol` lower operably connected with said fuel valve, a throttle, means including a second cam and a second cam follower operably connected with saidthrottle and linked with said fuel valve,

both of said cam followers being arranged to llimit opening movement of said fuel valve, said second cam and said second follower being'so constructed and arranged as'to permit opening of vsaid fuel valve upon part opening or" said throttle until prevented by engagement of said rst-'mentioned cam with said first follower, further opening of said throttle beyond a predeterminedpart opening being effective to disengage said second cam and said second follower from control of said fuel valve and to put said air valve in complete control of said fuel valve.

2. In a carburetor of the air valve type, spring means urging said air valve to closed position,

a fuel supply reservoir, a nozzle in communication with said reservoir, fuelv metering means including a fuel valve, spring means urging said valve to open position, a follower operably connected with said fuel valve, a throttle, a first ing movement of said fuel valvel while said throt` tle is being turned through a range of from closed position to a position of predetermined part opening, said first means comprising a movable cam member connected movable with said air valve and engageable by said follower, and said second means comprising a movable member connected movable with said throttle and engageable with said follower, said second means being arranged to move said foilower out of engagement with said cam member and to adjustably limit opening of said fuel valve while said throttle is being turned from a predetermined position of partial opening to closed position.`

GEORGE A. BREEZE.

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