US1788338A - Carburetor - Google Patents

Description

E. SEIGNOL Jan. 6, 1931.

CARBURETOR Filed Feb. 26 1926 llflliilliisvill.it!

Pa tented Jan. 6, 1931 UNITE STATES PATENT omen."

nnoumn srrcuon, or mars, rmcn cmrmnron.

Application filed February 26, 1926, Serial No. 80,958, and in France April 80,1985.

This invention relates to carburetors and more particularly to carburetors for internal combustion engines and which operate to suply fuel from a level below that of the caruretor or the engine intake, and without the intermediation of a vacuum tank and constant level reservoir.

In carburetors of the above type, especially when used on automobiles where the main fuel supply-tank is situated at the rear of the car well below the level of the engine and remote therefrom, and the level of fuel in the supply tank is subject to considerable variation, the rate of fuel supply is sensitive to such variation in level with resultant undesirable variation in the performance of" the level of the fuel in the main supply tank Other objects of my invention will be aparent and readily understood from the folowing specification and the drawings accompanymg the same.

The invention is illustrated by way of example in the accompanying drawings in wh1ch Fig. 1 is a diagrammatic sectional view of a carburetor embodying the principles of my invention, and

Fig. 2 is a modification'of the arrangement of Fig. 1. I

Referring to the drawings in detail, and first to Fig. 1, a is the Venturi tube of the secondary carbureting device arranged to be connected at its flanged right hand end to the intake manifold of an internal combustion engine, not shown. On the engine side of the neck of the Venturi tube is provided a throttle or regulating valve 6. A rich-mixture tube d of large diameter communicates at its upper end with the interior of the secondary Venturi tube a, as shown, at a point on the engine side of the neck a between the neck and the throttle valve b, and connects at its lower end with the tube f situated in close proximity to and slightly above the level of the main fuel-tank e which tank, in the case of an automobile, is situated at the rear of the car. A fuel conveying tube 9 of a small diameter extends. from the neck of the primary Venturi tube f down into the .main fuel tank e to a point close to the bot- .tom of. the tank.

For supplying a mixture of air and fuel for running at reduced speed or idling, the

chamber f is in communication with the'tube g by which the fuel, or rich mixture or emul-.

sion of fuel and air is lifted to the primary Venturi tube 7 from the main tank e.

The lar e diameter tube d is of sufiicientsize to con not a rich mixture of air and fuel in which the amount of fuel moved corresponds to that necessary for the engine. In carburetors of this generaltype making use of a rich mixture tube of considerable length, it may occur that at the time of sudden opening of the throttle valve 6 for the purpose of accelerating the engine speed, the mixture in the tube d may not be sufficiently rich to insure correct carburation because of the large amount of air enterin the tube a at such time, or on the other hand t e column of mixture in the tube (1 may have a very slow speed orma even be substantially still, either of whic conditions results in a delivery of substanti ally all air through the secondary Venturi tube to the engine, delaying acceleration or even stalling the motor. To prevent such ex-' cessive air delivery upon sudden openin "of the throttle valve, and to hasten the pro uction of there uired rich mixture for acceleration, I provi e the shutter'i for the inlet end of the secondary Venturi tube a, pivoted on.

the spindle 7' and connected through crank 70 and link Zto the rod m of an operating piston -n. The piston n, whose surface is smaller than that of the shutter 71, is slidable in a cylinder 0. J This cylinder communicates with the manifold of the motor (not shown) through an opening in the tube a between thetube a. A small vent hole 1' is provided at the throttle valve 6 and the motor. A threaded needle valve g serves to regulate the capacity of the passage between the cylinder 0 and the opposite end of the cylinder 0.

To render the primary Venturi tube or carbureting device f self compensating for variations in the height of fuel in the main tank 6, its fuel supply tube 9 is provided with a seriesofsmall openings g g g communicating at different levels with a tube 9 open to the atmosphere at its top. These small openings operate rogressively to admit air into the tube 9 w ich airmixes with the fuel in tube 9 reducing the specific weight of the contents of the tube progressively as the level of the fuel in the tank e lowers past the level of the small openings. While only three points of communication are here shown between the ,tubes 9 and 9, it is to be understood that they may be as numerous and arranged as closely together as required according to the fineness of graduation of compensation desired.

In operation, with the motor running at normal speed, the valve 6 being open, the draught of air through the secondary Venturi tube a keeps the shutter 11 open owing to the difference in surface area of shutter 2' and piston n. The latter is at this time at the outer end of the cylinder 0. When, in order to idle, or run the motor slowl the valve 7) is closed, the air draught or suction on the shutterz' ceases leaving the shutter free to be actuated by the operating piston n. Conseuently at this time the vacuum between the t rottle valve 6 and the motor being very high, operates on the piston n to cause it to move toward the inner end (right hand end) of the cylinder 0 and move the shutter into the closed position as shown. v

When, in order to accelerate the motor from slow or idling s eed to normal speed, the valve 6 is opened, t e vacuum in the manifold of the motor acts simultaneously on the shutter i and the piston n. Owing to the difference in surface area the shutter i will open, its speed of opening being retarded or slowed down by the dash-pot effect of the piston n and valve 9. Thus the vacuum suddenly produced in the secondary Venturi tube a upon the sudden opening of the throttle 6, instead of suddenly drawing in a great amount of external air, operates first on the tube 01 to accelerate the movement of the rich mixture therethrough, and cause an immediate increase in the action of the primary Venturi tube fto produce the required amount of rich mixture, without an excess of external air, after which the shutter 2' becomes completely opened. This opening of the shutter can be made to take place as slowly as desired by suitable regulation of the needle valve q.

During either slow or normal running of the motor, any variation in the'level of the fuel in the tank a relative to the primary Venturi tube f will be compensated for by a corresponding variation in the specific weight of the contents of the tube g, the mixture or emulsion of fuel and air in the tube 9 becoming leaner as the small holes g 9 etc., are successively permitted to communicate with the atmosphere through the lowering of the liquid fuel level, or vice versa.

It is to be noted here that while the density or richness of the mixture in tube 9 varies, the range of variation necessary for sufficient compensation is slight, the range being restricted by the smallness of the holes g 9 etc., so that the. mixture never becomes lean enough to interfere with the operation of the motor.

In the modification of Fig. 2 the pipe for idle running, instead of being connected for taking mixture directly from the primary- Venturi tube 7, is connected to the large main supply pipe 03 near the secondary Venturi tube a, the pipe d being provided with a reduced portion (Z between the Venturi tube a and the point where the idling tube connects in order to give at said point of connection a slight increased resistance to the passage of air.

With this arrangement, when the motor is running normally, the vacuum in d is greater than in the idling pipe. The rich mixture produced by f is drawn through d and d and when I) is sufliciently opened there even occurs a slight suction through the idling pipe towards d When the motor runs idle, the valve 1) bein closed, the degree of vacuum in the idling tue is high with the result that a partial vacuum is produced in d and air enters.

through d into (i, but as d has a smaller cross section than d some air is also sucked through f lifting fuel from tank e to produce a rich mixture. This rich mixture fur-- 1. In a carburetin g system, the combination with a main conduit connecting with the engine. a main fuel supply tank at a level below that of the engine and relatively distant therefrom, a primary Venturi tube located near the said tank, a secondary Venturi tube in the said main conduit, a relatively large tube connecting the outlet end of the primary venturi with the inlet end of the secondary venturi 'for conveying rich mixture from the primary Venturi near the tank to the secondary Venturi, a fuel supply tubeleading main conduit connecting with the engine, a

fuel supply tank at a level below that of the engine and relatively distant from the latter: a fuel supply tube leading from said tank for sucking fuel therefrom; an air passage leading into the tank and communicating at diflerent levels with said tube whereby the specific weight of the mixture of fuel and air in said tube is varied in accordance with I variations in the level of fuel in said tank;

a primary Venturi tube located near the tank.

in communication with said fuel supply tube and relatively distant from the engme and below the level of the latter and adapted to produce a rich mixture of fuel and air; a secondary Venturi tube in the main conduit connecting to the engine; a relatively large time for conveying rich mixture from the primary venturi near the tank into the secondary venturi in the main conduit; a relatively small tube adapted to conduct fuel for slow running directly from the said primary venturi into said mam conduit at a. point bea tween the Venturi tube in said main conduit and the engine; and a throttle valve located in said main conduit between the Venturi tube therein and the point where said small tube communicates with said main conduit.

In testimony whereof I have aflixed my signature.

- SEIGNOL.

Images