US1942005A - Carburetor - Google Patents

Description

Jan. 2, 1934. 'F Q SCHRAMM 1,942,005

CARBURETOR Filed Oct. 17. 1931 2 Sheets-Sheet l @Ms/MM 2 Sheets-Sheet 2 CARBURET OR Jan. 2, 1934.

Patented Jan. 2, 1934 UNITED STATES PATENT Erica f 1 Claim.

This invention relates to a carburetor for gas engines which will automatically provide variations of mixtures of fuel and air for different conditions of operation of the engine, such as changes from slow speed to high speed and vice versa and changes in load conditions.

In carrying out this invention a slidable venturi is provided in the carburetor which will assume different positions with respect to the fuel lll jetor jets at different times. The invention is suitable for carburetors that are installed either vertically or horizontally or at an inclination to the vertical. l Y

One of the objects of this invention is to provide means that will operate automatically under various load conditions so that suitable car- Yburetion will result to meet the requirements for slow engine speed and heavy load conditions to high speed under either light or heavy load conditions. n

The invention will loe-understood from the description in connection withthe accompanying drawings in which Fig. 1 is a vertical section through an illustrative embodiment of the invention and Fig. 2 is a similar section partly brokenaway showing modifications of some of the parts.

Y In the drawings reference character 1 indicates a carburetor casing, which may be of any one of a number of well-known types having a base portion 2 and a neck portion 3 havinga throttle valve 4 therein. A flange 5 may be prov ded at the end of the neck portion by means of which the carburetor can be attached to a manifold or a connection to a manifold.

The base portion of the carburetor is connected as indicated at 6 to the usual fioat chamber that is provided for maintaining a constant liquid level from which fuel is fed to the jets. Air is drawn by the suction in the manifold through the carburetor in the well-known way through the inlet 7.

The venturi 8 which is provided in the neck portion 3 of the carburetor surrounding-the tubes which feed gasoline is, in accordance with this invention, made longitudinally movable in the neck portion 3 and is so situated that the smallest cross sectional area of the opening through this venturi is located approximately at the liquid level in the jet as maintained by the float chamber. The venturi 8 may be provided with one or more longitudinally extending slots 9 along the outside thereof. Pins 10 extend into the longitudinal slots 9. Coil springs 11 are installed 55 in the slots 9 between the lower ends of these slots and the pins to return the venturi 8 to its 'A' initial position after it has been moved therefrom and the conditions whichV caused it to move have ceased. Small bumper springs 11 are installed between the pins 10 and the upper ends of the 50 slots 9. f

In the illustrative embodiment of the invention shown in Fig. 1 a plurality of concentric tubes or jets 12, 13, 14 and 14 are shown for providing liquid fuel to the carburetor. The innermost tube @5 12 extends farther than the others. The intermediate tube 13 terminates short of the tube 12 and is large enough to provide an. annular space between the two, and the two outermost tubes 14 and 14' are of the same length and are short- 70 er. than the others. The tube 14 isalso large enough to provide an annular space between it and the tube 13 and the tube 14' is large enough to provide an annular space between it and the tube 14. These tubes or jets are of such lengths 75 -that the Vouter or exit ends of the tubes 14 and 14' terminate approximately at'the smallest portion of the opening'through the venturi 8 when the venturi is in its innermost position orl positi-on of greatest retraction bythe springs ll. .80 TheV tube 12 terminates even. with the narrowest portion of the venturi 8 when itis in Vits outermost positon and the tube 13 terminates approximately half-way between the tubes 12 and 14. y

The tubes or jets 12, 13, 14 and 14 are fed from 85 the float chamber, as indicated at 15, andv the liquid levels in these three tubes are approximately at the endof the outermost tubes 14 and 14'V when the engine starts. The outer walls of the tube 14 may be provided with perforations 90 16 so that the tubes 14 and 14 communicate with each other and the feed 15 is provided with openings 17 so that fuel is fed directly from it into each one of the tubes 12 and 13. Liquid fuel passes from the end of the inlet 15 into the tube ,95 14.

In the modification shown in Fig. 2 annular recess 21 is provided along the inner surface of the neck portion 1 and an annular ring or rib 22 is provided on the venturi 3 extending into the 1,00 recess 21. A coil spring 23 is installed in the recess 21 above the ring 22 to return the venturi 8' to its initial position and a bumper spring 24 is installed in the recess 2l below the ring 22.

The longest tube 25 is fed at the lower end "1,05 thereof through a restricted inlet 26 from a compartment 27 into which the feeder 15 introduces the liquid fuel or gasolene. The intermediate tube 28 communicates with said compartment 27 through a restricted opening 29 and the tube 30 .1:10

communicates with said compartment 27 through a restricted opening 31. The outermost tube 30' communicates with the tube 30 through openings 32.

The upper portions of the tubes or jets 25, 28, 30 and 30' are surrounded by a draft tube 33 which is kept in place by means of the support 34 so that the outer end of the draft tube extends slightly less towards the outside than the outer end of the tube 25. The upper end of the draft tube 33 preferably terminates somewhat short of the smallest part of the opening through the venturi 8'. The tubes 30 and 30 terminate a considerable distance short of the outer end of the tube 25 and the tube 28 terminatesr approximately half-way between the tubes 25 and 30.

A removable plug 35 maybe provided through which the tube 25 can be withdrawn and a removable plug 36 keeps this tube 25 in place.

The venturi with the abrupt shoulder 20 may beusedin either embodiment of the invention and the same is true of the annular recess 21, ring 22 and coil spring 23. The plurality of' liquid fuel jets may also be used in either embodiment of the invention and advantageous results are obtained with the movable venturi whether two or more liquid fuel jets of different lengths are employed and Whether they are concentric with each other or not.

Tests with the device indicate that with an abrupt shoulder as shown at 20. in Fig. 2 a better mixture of gas and air is caused and the venturi appears to move to the different desired positions with greater certainty than is the case with the shoulder omitted.

In the operation of the embodiment of the invention illustrated in Fig. 1 when the venturi 8 is at its lowest or innermost position the smallest diameter of it is approximately evenwith the tubes of the lowest range jets 14 and 14'. This causes the exit ends ofthe low range jets 14 and 14 toV be in a'high suction area and therefore when the motor is started discharge ofvr fuel takes place from these two jets. As the speed of the motor increases, due to control by the throttle 4, the suction .increases and when it reaches a point where it is sufficiently strong to move the venturi 8 outwardly and compress the spring 9, the venturi moves outwardly'. This causes the highl suction area or most restricted portion of the venturi to be even with the tip of the next jet 13. The strong suction at this jet then causes fuel to'be drawn up the jet and out the discharge exit of it.

When this action takes place the low range jets 14 and 14 gradually cease to discharge fuel, as they are no longer in the highest suction area. As the throttle is opened farther and the suction becomes still greater, the venturi moves to its outermost position, thus causing the high suction area to be located near the exit end of the jet l2. Fuel is then discharged from this jet While less fuel is discharged from the jet 13 and very little, if any, from the jets 14 and 14'. Changes in the position of the throttle 4 cause changes in the motor speed and suction. When the suction decreases the pressure springs 9 return the venturi 8'.. By properly proportioning the parts and providing springs 9 of the right sort, a carburetor of this sort can be produced which is suitable for any desired sort of service, thus causing feed of fuel from the different jets in accordance with conditions of load and speed.

The operation of the embodiment of the device illustrated in Fig. 2 is somewhat similar to that already described. In this embodiment air is drawn through the draft tube 33 at high velocity at the start, or at low speeds of the engine, thus causing fuel to be discharged from the jets 30 and 30', the venturi 8' being aty its innermost position, thus leaving only a small annular space between the outer end of the draft tube 33 andthe opening through the venturi 8'. As the speed and suction increase and the venturi is moved outwardly, the discharge of fuel begins to take place from the jet 28 and the discharge from the jets 30 and 30' decreases as more air passes along the outside of the draft tube 33. When the venturi 8 reaches its outermost or highest position the smallest part of' the opening through it.v is some distance away from the upper end of the draft tube 33, thus causing fuel to discharge from the jet 25 and less from the other jets as more air then passes along the outside of the draft tube 33 instead of passingfthrough it.

What is claimed and desired to be secured by Letters Patent is z A carburetorhaving a longitudinally movable venturi through whichv unobstructed fuel and' air pass, and fuel jets terminating at different positions within said venturi, the greatest difference between terminals of said jets being substantially equal to the length of movement of said venturi and a draft tube surrounding said jets and discharging into said venturi.

FRED CJ. SCHRAMM.

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