US2790633A - Constant level mechanism for carburetors - Google Patents

Description

April 30, 1957 6.1:. SELDON 2,790,633

CONSTANT LEVEL MECHANISM FOR CARBURETORS Filed April 22, 1953 2 Shoots-Sheet 1 I IIIIJIII l l I man April 30, 1957 G. E. SELDON 2,

CONSTANT LEVEL MECHANISM FOR CARBURETORS Filed April 22, 1953 2 Sheets-Sheet 2 United States Patent O CONSTANT LEVEL MECHANISM FOR CARBURETORS George E. Seldon, Kirkwood, Mo.

Application April 22, 1953, Serial No. 350,279

12 Claims. (Cl. 261-72) This invention lies in the field of carburetion, wherein a liquid fuel is sprayed into a stream of air making a combustible mixture suitable for burning in an internal combustion engine. This mixture, under ideal conditions, comprises of a rather narrow range of ratios by weight of liquid fuel and air. Variations from the ideal can be noticed in the performance of the engine and great variations will not permit the engine to run.

Modern carburetors ordinarily consist of a body section usually die cast with a bowl for the fuel at its periphery- Through the center of this cast frame work there is usually a mixing chamber comprising a passage for air which assumes the shape of a venturi and at the center of its throat is the nozzle or jet for introducing the liquid fuel into the air stream. A fuel passage, or tube normally connects the bowl and nozzle. regularly placed, which actuates a valve permitting the fuel to enter the carburetor. Thus fuel is added as fast as it is removed through the nozzle by the action of the float and valve to hold the fuel surface level at a predetermined location, relative to the frame casting and the nozzle. The throttle valve is placed at the outlet end of the venturi which throttle in down draft carburetors is at the bottom. A choking butterfly valve may be added to the intake side of the venturi to facilitate starting. An air cleaner is usually provided ahead of the air stream especially when there is liable to be dust in the air.

Heretofore carburetors have used an open top fluid tight bowl for containing the liquid fuel. A float with lever arm was fulcrumed in this pool and this arm actuated a valve which opened on low fuel level, permitting fuel to enter the pool. The arm biased the valve to a closed position as soon as the level was restored tothe pre-set level. This conventional method has some inherent problems If the float is made of wood or cork, it becomes water-' logged, sinking lower than normal, causing a disastrous change in the level of the fuel in the bowl. Since a preset difference of elevation between the surface of the fuel and the jet outlet must be maintained for correct carburetion, one sixty-fourth of an inch, plus or minus, from the correct value of about three-sixteenths is scarcely allowable. This head on the jet outlet, or nozzle, is a pertinent factor controlling the ratio of fuel to air mixture and the quantity flowing is not a simple ratio of the head, but is proportional, numerically to the square of the head in units of linear distance. Thus, this setting becomes critical and may not be disturbed. If the float is made of metal it must be thin sheet in order to keep the weight practical. The parts must be hermetically sealed in order to prevent the waterlogging above mentioned. However, in this case, a backfire from the engine can collapse the sides and again the float sinks below its proper level.

Heat also caused trouble in the stationary bowl'carburetor. Heat conducted through the metal of the manifold from the engine traveled to the carburetor and In the bowl a float is ice escaped through the bowl, causing the fuel or gasoline to boil and evaporate. This action is most noticeable on hot days after a long drive with the engine thoroughly heated, when boiling in the bowl persists, even though the switch is turned off and the engine is stopped. Often the entire charge of liquid in the bowl was evaporated making restarting after a short stop of a few minutes diflicult, if not impossible.

The float type level control is extremely sensitive to head or pressure on the float valve. A higher pump pressure will cause higher liquid levels. While the carburetor manufacturer may be quite careful to set his float properly, a low pressure pump or high pressure pump will cause wide variations in fuel delivery at the nozzle for the same air flow.

It is an object then of this invention to provide a liquid level control in a carburetor that cannot become watercontrol in a carburetor, that cannot be collapsed by backfiring from the engine.

It is a further object of this invention to provide a liquid level control for a carburetor that has air insulation and is not as subject to vaporization due to heat, as the ordinary float and bowl heretofore used.

It is an object of this invention to restrict the flow of heat by conduction through the metal of the carburetor body from the hot exhaust manifold and engine to the volatile liquid gasoline.

It is a further object of this invention to provide these advantages at no additional manufacturing costs; to provide simpler and more direct linkages and elements; to shorten the fuel passages and simplify the complex plumbing usually found in carburetors, thereby reducing the machining required and the structure housing the long drilled holes. All this adds up to lower initial cost, less service trouble, simpler and less tooling, simpler or fewer dies, molds and patterns.

It is a further object of this invention to provide a liquid level control that is not sensitive to variations in head on the valve at the carburetor, i. e. a control that will hold the head on the nozzle, or jet, constant regardless of the head or pressure against the carburetor.

It is a further object of this invention to provide a liquid level control for carburetors that is not affected by motion of the car over rough roads and the like.

These and further objects will be apparent in the description and disclosures following.

Figure 1 shows a plan view of the carburetor along the 7 plane BB of Figure 2.

control balanced out with a spring, rather than the weight (air cleaner may surround entire carburetor).

shown in Figures 1 and 2.

Figure 4 shows a section along a plane line CC of Figure 3. It also shows the spring balancing device, plus a liquid displacing bowl.

This carburetor comprises a body or a frame 1 and a cover 2 which closes the top. At the right side of the body is a mixing chamber 3, which contracts to the throat 4 of a venturi. At the top of the passage, a ring 5 is cast, which may hold a choke valve and an air cleaner For sake of simplicity, the choke valve is not shown here. At the base of the mixing chamber 3 is bolted a throttle barrel 6, in which is fulcrumed a butterfly throttle valve 7 mounted on a throttle shaft 8. The barrel 6 is separated from the body 1 by a piece of insulating gasket material 9. At the throat 4 of the venturi is located the fuel outlet or nozzle 10, which is one end of tube 11, which extends into the pool of fuel 12. This fuel is contained in a pan structure 13, which is fulcrumed on bearings about pins 14.

The pan structure 13 is pendulous. and has limited motion about this fulcrum 14, being stopped in the downward direction by the valve 15 engaging the seat 16. In the upward direction the pan 13 is stopped by hitting the bottom of the tube 11. The pan 13 and its measured quantity of fuel is balanced by the weight 17 cast onto the left side of the pan structure 13, that is the forces on each side of the fulcrum balance and are in equilibrium. As shown, the valve 15 engages the bottom of the pan extension and is moved up and down by the motion of the pan. The valve 15 moves in the opposite direction to the pan 13. In its uppermost position, it is seated upon the valve seat 16 in the tube 18, preventingfurther flow of fuel into the bowl. As the fuel is drawn out of the pan through tube 11 and nozzle 1% into the air stream at the venturi throat 4, the level is lowered and reduces the weight of the fuel in the pan. The balancing weight being constant now drops, allowing the valve 15 to move off its seat 16. This permits fuel to re-enter the pan and increases the weight of fuel in the pan, moving it back till the limiting position of the pan is reached. This limiting position coincides with the correct fuel level in the pan and is about below the nozzle.

While the preferred vertical displacement of the outlet above the surface level 23 of the fuel is about 7 (0.188), the nozzle 10 may be placed as low as the surface of the fuel and any desired height above the surface 23.

Fuel enters the pan through the inlet passage 18 and is Withdrawn through the tube 11 and at any instant there is a remainder of fuel left in the pan and this remainder has a definite weight. Between stops the pan is pendulous about the pins, and hence must be in equilibrium if at rest. The moment of the weight or counterpoise substantially equals the moment of the pan and the remaining fuel in the pan, and the center of gravity of the pan structure assembly with its pan and fuel contents must lie directly below the pins.

A line through the center of gravity of the pan structure assembly with its pan and fuel and fulcrum pin is vertical. When the elements of the pan structure, pan and fuel contents are at rest. and not touching the stops, the moments of all their weight forces and counterbalancing forces are equal. The pan structure is now balanced about the fulcrum pin, and the Weight forces of the elements and the counter-balancing force are in equilibrium or are equilibrated. Looking at Figure 2 the valve is just closed, the surface of the fuel is. as close to the rim of the pan 13 as it can get and the quantity, therefore the weight of the fuel in the pan is a maximum. Now remove some of the fuel at the nozzle 10 and the surface is lowered in the pan. The weight of fuel is reduced and equilibrium has been destroyed. The moment of the pan and its fuel contents is now less than that of the weight or counterpoise and it can only be equilibrated by motion of the pan structure about the pins in an anti-clockwise direction. The horizontal arm of the fuel weight increases while the horizontal arm of the weight decreases to a point restoring the equilibrium. In the pan a greater weight of fuel biases the valve shut and a smaller weight of fuel biases the valve open. There is a valve position corresponding to every pan position and therefore weight of fuel in the pan. The stops limit the angle of rotation of the structure to 10 to 15 about the pins, this however is adequate to fully open the valve. The position of the valve and the attitude of the pan structure is a function of the Weight of fuel remaining in the pan at any instant. There is a range of valve positions and corresponding weights of fuel in the pan. Outside forces acting on the pan structure must be applied through the.

pins and since these forces are vertical there is no moment arm to turn the structure about the pins.

The external accelerating forces are vertical in direction and parallel to the line between the fulcrum pin and the center of gravity of the pan assembly. The external force can only be applied at the pin and so can have no moment arm about the pin and hence no effect on the equilibrium of the pan assembly and counter-balancing weight about the fulcrum pin. This is the means. used to prevent external forces from disturbing the valve setting established by the weight of fuel remaining in the pan at any instant, in a weight balanced pan structure assembly.

The fuel enters the carburetor through the tube 18 and a connector (not shown) screwed into the threaded end 19, of tube 18. The connector fitting and the threaded opening are standard and are not shown for the sake of simplicity.

The body 1 has a floor 20, which closes the bottom of the carburetor. At the bottom of the pan space, near the mixing chamber, is a vent 21 to prevent the flooding of the carburetor, by fuel accidentally spilling over the sides of the pan. The fuel is brought to the carburetor under pressure of a pump or gravity, by standard means and it is not novel to this disclosure. It is merely important to point out that many dissimilar head pressures arise due to variations in pumps, voltage differences on pump motors, causing variations in R. P. M. and many other causes.

The throttle barrel 6 is bolted to the intake manifold 31 of the engine, but for the sake of simplicity and since the novelty of this carburetor does not lie in this connection, it is indicated in part only. This inlet manifold, however, is directly connected to the engine and regularly has a section of the exhaust manifold running through it, to supply heat to vaporize the fuel leaving the carburetor. An air cleaner 35 comprising a flange 32 fitting on collar 5 of the carburetor holds a filter section 33 and a cup 34 covers the top, so that air entering the carburetor must pass through the filter section 33. Oil placed in the trough of flange 32 keeps the filter oil soaked. The pressures under the air cleaner and in the pan compartment are usually equal because of I21 passage connecting them.

Fig. 4 shows a spring balanced pan structure. The structure 13, to the right of the pins consists mostly of a deep pan with its floor 24. To the left of the fulcrum pins 14 is a shallow extension of the pan with the valve pin 15 resting on the floor. An arm 25 extends still further to the left and has a notch 26 that accepts the loop 27 of the spring 28. The lower loop of the spring is threaded through the lug 30 cast into the floor 29 of the carburetor frame.

In. the position shown, the valve 15 engages the seat 16, the valve is closed, flow into the pan has stopped and the weight of the fuel in the pan is a maximum. The weight of the fuel and the pan to the right of the pins tends to turn the pan structure clockwise. The weight of half the spring, extension arm, and the pan extension, the valve pin 15 and the fuel in the pan extension all to the left of the pins tend to turn the pan structure anticlockwise. The metal mass of the structure to the left of the pins is considerably less than the metal mass of the pan to the right. While not exactly true, it can reasonably be assumed the metal of the structure to the left of the pins plus half the weight of the spring, plus the Weight of fuel in the extension, plus the weight of the pin 15 just balances the weight of the metal in the pan to the right of the pins. Then the spring 26 balances the Weight of fuel in the pan 13. The moment of the spring force about the pins just equals the moment of the fuel to the right of the pins. Assume the area of liquid surface in the pan to be 4.1 square inches. The weight of 1" depth would be .1163 lb. .02430 lb. per cubic inch of fuel. Assume the centroid of the fuel iOi be tax" to the right of the pins 14 in Fig. 4. Then the moment of fuel weight aboutthe pins 14 is 1.38X4.1X1X.0243#=0.l375 inch lb. Assume the spring is attached to the arm 25 at the notch 26. Assume also 0.1375 lb. per inch scale rate. The plan moves only about between stops at the far edge of the pan. Assume l of travel possible and that there is /2" of fuel in the pan and the elevation of the pool surface is just 5 below the nozzle. Now pour 2 cubic inches of fuel into the pan. The surface will then liaise 2.;+4.l=0.488" in the pan. The additional moment due to the 2 cubic inches=2 0.0243 1.38:0.0671 inch lbs. This stretches the spring 0.0671+0.1375 l=.488 inch or exactly the same distance as the fuel added. So the pan may float anywhere within its range of motion but the surface of the fuel 23 stays at exactly the same distance below the nozzle. Thus the head of liquid on the nozzle remains constant regardless of amount of fuel remaining in the pan at the instant considered. The force of the spring must be adjusted to just balance the pan with a full load of fuel GA below the rim) when the valve just closes. At this point the attitude of the pan structure is horizontal.

Figures 1 and 3 show straight vertical sides on the pan, hence as fuel is poured into the pan the volume in the pan increases, the depth increases proportionately to the volume also the weight of fuel increases proportionately .to the volume and the depth. A predetermined quantity or weight of fuel in the pan corresponds to a predetermined depth of fuel in the pan. Were the sides not straight or perpendicular but continuously rising a rela- .tionship between depth in pan and volume, weight and .quantity of fuel could readily be established.

Fuel under pressure from a pump or tank is admitted to the carburetor through tube 18. Fuel is removed from :the pan by the tube 11 with nozzle 10 in the venturi. The nozzle 10 is higher than the surface of the fuel in the pan. This prevents loss of fuel when there is no aspirating .air flow through the venturi 4. The tube 11 empties when there is no flow of air through the venturi. According to Bernoulis law, flow of air through the venturi lowers the pressure at the nozzle 10 sufficiently to lift the fuel and .to force it to fiow through the nozzle. The nozzle 10 is a restricting orifice in the tube 11 limiting or controlling the flow through the tube. As the fuel is removed from the pan the weight in the pan is reduced and the clockwise moment is reduced permitting the spring moment to move the pan to a new position in an anti-clockwise direction, opening the valve allowing fuel to flow into the pan. If the outgoing flow is high the incoming flow must also be high and the valve must move off the seat enough to permit the inlet flow to equal the outlet flow. This is true because if the outgoing fuel flow rlate exceeds that of the incoming rate the pan soon empties. As it empties the spring moves the pan structure in a clockwise direction lifting the valve off the seat still further increasing the incoming fuel flow rate. If the incoming rate is greater than the outgoing rate the opposite occurs until the two rates are equal. The pan structure attitude in this case is such as to hold the valve a sufficient distance from the seat 16 to set the rate. For every sustained discharge rate there is a corresponding inlet valve op'ening, pan structure attitude, a spring length and a specific quantity and weight of fuel in the pan. The flow demand sets these quantities by virtue of the spring sensing the weight of fuel in the pan rat the instant.

The discussion to this point has considered the pan only with no depending plug 22 displacing some of the fuel. In going over rough roads outside forces affect the vehicle and all its component parts. If these are free to move, motion results. The pan is pendulously suspended from the pins. The center of gravity of the pan structure and its fuel is to one side of the pins and outside forces when applied will change the valve setting. The plug 22 depends from the frame of the carburetor 6 land displaces some of the liquid. As shown above the fuel surface level is kept at the line 23 relative to the carburetor. The plug displaces as much volume of fuel as the plugs external volume below the surface of the fuel. The force of the remaining fuel on the plug is the same as the force required to support the displaced fuel before it was displaced, and conversely, the force of the plug on the remaining fuel is the same as that of the fuel displaced. Provided the fuel surface level remains at line 23 the balancing force required by the spring is the same whether the plug is in the fuel pool or not. Neither 'does it matter how deeply the plug is pushed into the pool or how large it is, the spring force remains constant as long as the surface remains at the line 23.

Consider an external vertical accelerating force accelerating the vehicle upwlard. The carburetor is also accelerated and there is a plug having 75% of the fuel surface area of the pan depending into the fuel pool. The force is applied to the pan through the pins 14. The center of gravity of the pan and fuel being to the right of the pins, Fig. 4, the pan resists the change of motion. A couple tending to turn the pan in a clockwise direction is formed. The carburetor moves up leaving the pan relatively stationary. Assum'e the carburetor moves relative to the pan and the plug is then withdrawn from the pool surface. The surface of the fuel drops in the pan more rapidly than the pan because of the relative areas of the plug and pan. The total relative surface drop for The spring has been extended sufficiently to lift the pan A So the total force avail-able to resist the external forces required to move the pan $5 would move the fuel surface A without the plug. That is the 75% plug has a mechanical advantage of 5 to 1 to resist external forces acting on the balanced pan system. This resistance operates whether the accelerations are up or down. A plug with a higher percentage area relative to the pan has a greater mechanical advantage. Thus the plug depending into the fuel is the means whereby external accelerating forces are prevented from substantially disturbing the setting of the inlet valve as determined by the instantaneous weight of fuel remaining in a spring balanced pan system.

Fuel weight in the pan is the force sensed by the spring to control the position of the valve relative to the scat. Assume that a much higher than ordinary pressure is forcing the fuel into the pan. Now the valve being at its old setting the fuel enters at a greater rate than before, assume no change in rate of flow out of the pan. The excess fuel accumulates in the plan causing it to drop and move the valve closer to the seat pinching ofi flow. If the head on the carburetor is lowered the quantity in the pan is decreased and the pan rises to open the valve to permit increased flow. It has been shown also that the plug 22 in equilibrium conditions acts on the sensing spring or weight exactly the same as the fluid it displaces.

The ordinary carburetor has its bowl mounted directly on the throttle valve barrel. This barrel in turn, is usually mounted directly on the block or exhaust manifold to provide heat to vaporize the fuel as it leaves the throttle. This practice is especially useful for winter driving. Consistent carburetion demands that suflicient heat to vaporize the liquid fuel be constantly supplied. The flange on which the carburetor is mounted becomes very hot and often becomes dull red. This is fine as long as the car is in operation. But as soon as the engine stops, air flow through the carburetor also stops, no external cooling of any kind is available. Heat from the hot manifold travels into the bowl by conduction along a very good metallic path, the steel throttle barrel and the zinc bowl. Since the temperature at the throttle barrel is very high it causes the fuel in the bowl to boil violently and vaporize. The vapor escapes into the manifold through the high speed nozzle. The vapor in escaping, carries some solid fuel along with it andthis liquid falling into the hot,mani-- foldvaporizes too.- So whena start is again attempted shortly thereaften'the mixture is so rich it will not burn and the engine can not be started.

In the present improved constant level mechanism the pan is entirely surrounded by insulating air -and has no directmetallic connecting path to the hot-manifold, exceptth'at through the very small'loosely fitting trunnion pins 14. Obviously the heat flow-by conduction is effectively minimized, since flow (water analogy) is proportional to the area conducting-and inversely poiportional to the lengthof paththrough the conductor. In this present carburetor the path lies diagonally. across the entire outer case to the slender pins 14,- before entering the pan 13. Because of the loose fit of the pins in the pan 13 and the body 1,-the actualcontact is a line having insignificant area. Consequently, heat flow by conduction into the fuel body in the pan is greatly reduced over the bowl and float system now in use. The exterior case or frame of the carburetor does not formpart of the fuel containing bowl 'as was comon heretofore in this field. Thepan here lies within the exterior case or closure means. The boundries of this closure or compartment may be considered the walls or framework of the carburetor and the intake air port, is also covered by an air as before, and will get just as hot as before, so that desirable vaporization during operation can proceed as before the change of the float mechanism.

All carburetors with hollow metallic floats are hermetioally sealed to prevent fuel entry which would cause the float to sink lower in the fuel pool and which would thereby raise the fuel level in the bowl. These metallic floats are made as light as possible, hence are most vulnerable to dents and cave-ins due to carelessness in handling at assembly and repair shops. Backfires produce sudden high pressures in the carburetor bowl frequently collapsing the sides of such floats. This again sinks the float and automatically raises the fuel level in the bowl.

The pan type level control while still of all metal construction, has no hermetically sealed spaces. All surfaces of the pan and liquid are exposed to substantially equal pressures at all times. Hence no unbalanced pressures can build up to bend and distort surfaces of control elements. Backfires can not change the settings.

I claim:

1. In a carburetor having a venturi, a body having a fuel inlet tube, a pan structure, pivot pins intermediate of the length of said structure and supported by said body; a pan on one side of the pins and fulcrumed thereon, said pan being in communication with the fuel inlet tube and adapted to receive and store a supply of liquid fuel, a control valve for the inlet tube, means on said pan structure to actuate said valve; counter-balancing means on the other side of the pivot pins and connected to the pan structure, a fuel outlet tube depending into the pan and extending upwardly above the level of the fuel in the pan and discharging into the venturi, whereby the weight of the liquidfuel in the pan closes the valve when a predetermined weight is reached 2. A carburetor in accord ancewith claim 1 wherein the counterbalancing means comprises a spring disposed between the pan structure and a surface on said body and acting in opposition to the weight of fuel in the pan.

3. A carburetor in accordance with claim 1, wherein the counter-balancing means comprises a mass on the pan structurebiasing the pan inlopposition to the weight of s th re e- 4. A: carburetor-11in aceordancewithwclaim 1 wherein there-is :a plug depending from the body into the pan,

weights. of fuel in the pan and the weight of fuel displaced by the submergedportion of the plug.

5. In a vehicular carburetor, a ,body with a venturi, a fuel inlet tube and a valve to. control the flow therethrough; a fulcrum pin mounted in said body, a pan structure fulcrumed intermediate its length on said pin, means whereby. said 'valve is actuated by the motion of said structure about the pin, a pan on said structure to one side of the fulcrumpimsaid pan in communication with the fuel inlet andadapted to receive and store a quantity of fuel, a tube-to remove the fuel from the pan and dc liver it. to the venturi; means to counter-balance about the fulcrum pin, thepan structure and-the pan with its fuel contents; whereby the valve is open-only for quantities of fuel in the pan less than a predetermined amount, and means to reduce-the unbalancing effect of forces outside the carburetor on the elements equilibrated about the fulcrum pin.

6. A carburetor as in claim 5, wherein the counter-bal ancing means is a spring acting between the body and the pan structure in opposition tov the weight of the balanced elements about the pin; and the means to reduce the unbalancing effect about the pin, of forces outside the carburetor, being a plug depending from the frame into the fuel in the pan and displacing some of it.

7.A carburetor as in claim 5,-in which the counterbalancing vmeansis a weight on the pan structure on the side of the pin opposite the pan; and the means to reduce the unbalancing effect of forces outside the carburetor on the elements equilibrated about the pin is the alignment of the fulcrum pin and the center of gravity of the equilibrated elements in the same direction as the unbalancing forces.

8. A carburetor as in claim 5, in which a counterpoise on the. pan structure on the side of the pin opposite the pan counter-balances the pan structure, the pan, and the fuel contents in the pan about the pin; and the line between the fulcrum pin and the center of gravity of the balanced elements is substantially parallel to the forces outside the carburetor tending to unbalance the elements about the fulcrum pin.

9. In a vehicular carburetor, a body with a venturi, a fuel inlet tube with a flow control valve therefor; a fulcrum pin in said body, a pan structure fulcrumed inter mediate its length on said pin, means on said structure to actuate the control valve, a pan mounted on said structure to one side of the pin, said pan in communication with said fuel inlet tube to receive and store a quantity of fuel, in said pan the depth of the fuel increases as the quantity increases, a tube to remove fuel from the pan and deliver it to the venturi; means to counter-balance the pan structure, the pan and the fuel contents about the fulcrum pin, whereby the valve is open only for depths of fuel in the pan less than a predetermined depth, and means to reduce the unbalancing effects on the elements equilibrated about the fulcrum pin of accelerating forces outside the carburetor.

10. In a vehicular carburetor, a body with a venturi, a liquid fuel inlet tube with a valve to control the flow therethrough; a fulcrum pin in said body, a pan structure fulcrumed on said pin, means for actuating said valve by the motion of said structure about the pin, a pan on said structure to one side of the fulcrum pin, said pan in communication with the fuel inlet and adapted to receive and store a quantity of liquid fuel said quantity proportional to the depth of fuel in the pan, a tube to remove the fuel from the pan and deliver it to the venturi; a spring to counter-balance the pan structure, the pan and its fuel contents about the fulcrum pin, whereby the valve is open only for a liquid fuel depth in the pan less than a predetermined depth and the inlet valve is positioned according to-depth" of liquidfuel in the pan, being open only for those fuel depths in the pan less than the predetermined depth; and a plug depending from the body into the liquid fuel in the pan and displacing some of it, said immersed plug being the means to minimize about the fulcrum pin the unbalancing effect of external forces on the said internally equilibrated pan structure, pan with fuel contents and counter-balancing spring.

11. In a vehicular carburetor, a body with a venturi, a fuel inlet tube with a valve to control the fuel flow therethrough; a fulcrum pin on said body, a pan structure fulcrumed on said pin, means whereby said valve is actuated by motion of said structure about the pin, a pan mounted on said structure to one side of the fulcrum pin, said pan in communication with said inlet tube and adapted to receive and store a quantity of fuel, means to counter-balance about the fulcrum pin, the structure, the pan and its fuel contents, a tube to remove fuel from the pan and deliver it to the venturi, the inlet end of said tube submerged in the fuel in the pan and the outlet end in the venturi, said inlet portion of the tube depending from the body, and at all times a space separating said tube from said moving pan structure and pan, said tube continuous from inlet opening to the outlet opening, and said outlet opening at least as high as the surface of the fuel in the pan.

12. In a vehicular carburetor; a body having a venturi, a fuel inlet tube with a control valve therefor and a fulcrum pin; a pan structure fulcrumed on said pin, means whereby said control valve is actuated by motion 10 of said structure about said pin, a pan to one side of the fulcrum pin, said pan in communication with said inlet tube and adapted to receive and store a range of quantities of fuel, a fuel outlet tube with an inlet opening in the fuel in the pan and an outlet orifice in the venturi, means to counter-balance the pan and its range of quantities of fuel contents about the fulcrum pin, said counter-balancing means of such proportions to hold the valve open for the range of quantities of fuel less than the predetermined quantity, said counter-balancing means effective for a range of pan positions and corresponding range of quantities of fuel, and the lower surface of said range of fuel quantities contacting the pan bottom and moving with the pan, while the upper surface of the range of quantities of fuel remains substantially a constant distance below the outlet orifice of said outlet tube.

References Cited in the file of this patent UNITED STATES PATENTS 1,776,983 Tice Sept. 30, 1930 1,933,379 l\d0ck Oct. 31, 1933 2,141,365 Schuttler Dec. 28, 1938 2,303,235 Seldon Nov. 24, 1942 2,345,168 Wirth et al Mar. 28, 1944 2,613,686 Parson Oct. 14, 1952 2,616,444 Norland NOV. 4, 1952 2,629,396 Toadvine Feb. 24, 1953

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