US1778868A - Carburetor - Google Patents

Description

E. SCHIMANEK CARBURETOR Filed March le,

1927 2 Sheets-Sheet.

E. scHlMANEK Oct. 2l, 1930.

CARBURETOR Filed March 16.

1927 2 Sheets-Sheet 2 l l 1 l 1 n 1 Patented Oct. P2l, 1930 UNITED? s'rAia'sV4 l PATENT OFFICE EMIL SCHIMANEK', 0F BUDAPEST, HUNGARY, .ASSIGNOR'TO THE FIRM HERMES MAG- YAR ALTALANOS VALTOUZLET RESZVENYTABSASAG, BUDAPEST, HUNGARY animamos Application mea March is, i927, serial m. 175,872, and, in Hungary september i1, isa's.

This invention relates to a carburetor in which the whole amount of -air drawn through the carburetor is utilized for primary and secondary mixing purposes, and a member is provided fory regulating the secondary mixture and controlled by the negative pressure at the secondary mixing point (which member has an internal passage for conveying the primary lmixture to .said secondarymixing point) said member maintaining thenegative pressure constant at the said point, irrespective of the variations in the number of revolutions of the engine fed by the carburetor.

It is essential that such automatically regulating carburetors must comply with two opposed conditions: first, having re ard to good volumetric eiiciency ofthe engine, the negative pressure maintained constant at the point of secondary mixing by the automatic regulating member must be as small as possible, for the reason that if the said pres' sure is very pronounced at this point, the

maximum quantity of the charge drawn into the engine cylinder is reduced; and, second, the morepronounced the negative pressure, the more thorough the atomization.

The present invention renders it possible to fulfill both conditions completely;' andit consists essentially in disposing between the fuel inlet controlled yby the regulating member, and the outlet opening of the'fuel passage provided in said member, an atomizing tube which widens towards the outl t of said passage and is provided with -air inlet openings.

In this way, the drop place between the suction opening and the outlet opening for the secondary mixture can be divided into two sta es. One of these stages, namely thgt whic acts on the mixture-regulating member and controls the'secondary mixture, can be suicientlysmall to affect as little as possible the maximum charge of the engine, while the other, namely the amount of negative pressure at the atomizing point in the atomizing tube can be substantially greater, in order that the atomizing may yield, together with the secondary mixing, as perfect a total eect as possible.

inv 'pressure' ta-lri'ng-v i Several5 constructions according to the invention are diagrammatically illustrated in longitudinal section, by vway of example, in the accompanying drawings.

Figure 1 shows a carburetor in which the atomizing tube is situated in the rod ofthe oating regulating piston;

Fig. 2 shows a slightly modified arrangement in which the atomizing tube .is vsub-l merged in theioat chamber, this being the preferred form;

Fig. 3 is a modification of Fig. y2, having -v means for effecting" double atomizing;

Fig. 4 .is another modification, showing the I automatic regulation of the atomizing air;

Fig.v 5 is still another modification, pro- In F ig. 1, 1 indicates the inlet openingthrugh which the air passes into the carburetor,. and 2r the outlet opening for the .secondary mixturewhichis .in communication with the induction ,pipe of the engine, said pipe having a throttle valve (not shown); 3 isa loating'piston which constitutes the regulating member and which-fis vertically movable inthe cylinder 4. L 5 is an opening in the cylinder 'wall which isuncoveredas the piston'3 rises, and 6 -is the oatfchamber containing the fuel, maintained ata constant level by the ioat 77 b y means of the ',v'alve' 8. l l'The`A piston 3 1s equipped with a hollow lrod 9 that extends downward from it into the oat charb'i, and into the lower end of this 'rod projects a tapered needle 10 which closes the fuel inlet 11 in accordance with the position of the piston. At the point 14'1where the mixture of fuel and air (produced as hereinafter described) passesth'rough the opening 5 into the mixing chamber 16, said mixture is mixed with the air entering said chamber i'n the Adirection of the arrow 15 and formsa secondary mixture, the first mixture being the primary one.

inc.,

The negative pressure prevailing atthe point 14 is transmitted-through an o ening 17 formed in a partitionprovided in t e pisf ton tothe space above the piston, so that-thesaid pressure effects the regulation by moving the piston when, for instance, owing to the increased number of revolutions of the engine, the negative pressure is. intensified, that is to say, overcomes the weightoil the piston and the action of its spring, if any.A

According to the invention, and in` order that the negative pressure acting on thejpiston shall be-.as small as possible, while pronounced negative pressure is .availablev for atomizing purposes, a Venturi tube 12 is connected'to the iloati'ng piston-3 and surrounds the upper` portion of therod 9. This tube widens toward the point 14;, where it opens into chamberj16, and it -is provided at its lower end with .an air inlet 13 which opens into thesuction chamber ofthe carburetor.

Pronounced negative pressure prevails inthe narrower lower portion iufsaid` Venturi tube, owing .to which 'the fuel" is atomized 4in an -eectivev manner, andv a richp'rimary mixture is ,produced, the pressure of which'is grad- 'ually increased inthe widening portion of the tube towards the point or opening 14. On

reaching this opening, the negative pressure is small, but suiiicient for thoroughly mixing. the'well-atomized primary mixture .with the abundant air supply at the opening 14. -h

The ybore 13" of therupper portion. of the piston rod v9 leads from the space1 above. the 1 piston 3 ldown to the point 13 where atomization takes place. The-space above the 'piston 31s in communication, through the opening 17, with the opening 14'which is under a considerably higher negative pressure than that "prevailing at point 13.' Consequently, aportion of the primary mixture flows through the opening 17, the bore 13"' o f the rod 9 and a small opening or openings 34 at' the bottom of said bore, in the 'direction of-lthe 'arrow 13 back to the atomizing point 13, owing to which the .atomizing is assi d.

V According to Fig. 2, the 'lower end ofthe Venturi-tube 12 extending from -thel floating piston 3 projects below thel level of the' liquid in thefuel chamberl 'intoa -ciip 18 which ,opens above the said level and which is mounted on the lower end of the rod- 9 disposed in the interior ofthe Venturi tube 12. The

lower portion of the Arod 9 has a bore 32 which is separatedfrom the bore 13" of the upper portion` by a partition 31 and into which .projects .the needle that controls or openings 34 just above partition 31 with the p I provided bythe interior of the atomizin tube 12, so that a portion of the.

primary mixture returns in the direction of arrow 13a, as before'.

In this construction, itis not necessary,l v

therefore, to raise the fuel to the atomizing point 13e, so' that the whole of' the-*negative pressure is thus utilized for. atomizing. .This

arrangement hasthe further advantage lthat while the engine'. is at rest'tlie fuel collects in the cup or chamber 18 until it reaches 'the level of the liquid inthe loat chamber, owing to which' a richer mixture is available .for )starting The arrangement shown Fig. 3 issimilar to that shown in Fig, 2', with the exception that a double atomizing operation occurs instead of a single one, the first one taking place at 19, andthe second at 2O..` The mixture return ,13b shown .in Figsl 1 land 2 isomitted here. l In the construction shown in Fig. 4, the quantity of 'air -used for the primary mixture is varied simultaneously with the quantity of air producing the-`sec0ndary mixture. To this end, the'airinlet 13 of the' atomizing tube 12 ,is situa-ted between the part offthat tube which is securedto the piston 3,-and the fuelsupply tube 28 which is secured to the carburetor casing. TheV needle 10 controlling the 'cross-sectional area ofthe fuel inlet 11 is also mounted onathe piston-.3. Consequently, the vertical movement of the piston likewise alters the width of the air inlet 13.

Fig. 5 shows :in-arrangement in which, by

cross-section ofltheropening' controlled by vfthe piston can be altered, while the level of .thepiston 3 remains invariable, owing tothe provision of'a depending skirt 21 .on the piston which acts as a slide valve to close the opening 5 to agreater or lesser extent. Theedge 7 offtheskirt 21 (Fig. 6') moves to the position 71,' more or less to the left of the ledge y of the opening 5, the" opening 111 remaining in any position 11---111 within reach of the opening' 5. In this way, while the open cross-sectional area :of the fuel inlet 11 re'- mains invariable, the cross-section.. aorded to the air passing through. the .opening 5, and

consequently the composition of the s'econd .ary mixture produced'at agivenlevel of the piston 3, can be altered.

'atomizationg and to this end,.the carburetor. shown in Fig. 5has a device for altering the Asaidgqua'ntity of air when the double atomzing feature of Fig. 3' is utilized." The lower portion 19 of the atomizerf12 projects into and is attached to cup'lS, and the latter is, mounted in a cylinder 23 secured to the carburetorfcasing,'so that the-atomizer and cup with an aperture 24I(-Fig. 7) for` cooperation 'witha pair of airinlet openings .In such a construction, 1t may be desirable. to vary also the quantityof air utilized for rotating the piston 13 about'its axis, thefree are thus' vertically adjustable and rotatable I' as a unit; said cylinder23 being provided formed in the cup and communicatin with thev interior of the atomizing tube. ence, the rotation of the piston 3 and the atomizing tube 12 secured to the same, will bring a more or less greater portion of the air inlet openings 22, 22a of said tube into register with the aperture 24 of the cylinder 23, resulting,

, in consequence, in a greater or a smaller quantity of air passing into the atomizer.

In the device shown in F ig. 8, the floating regulating p-iston is provided (with a certain amount of play)` with a resisting spring 26, so that, on starting, the engine suction first overcomes the weight of the piston only, and then the spring resistance. According to Fig. 8, the resisting spring 26 acts on the rod 25 secured to the piston and containing the fuel passage and arranged in the interior of the atomizing tube, so that the .inlet 13 for the atomizing air is between this rod and the wall of said tube; Consequently, the air inlet 13 is narrow in the lowest position of the piston, i. e., when starting. For this reason, the negative pressure acting on the fuel in the passage vis relatively high, so that the carburetor supplies at the start a rich mixture even if suction is weak, owing to the small number of revolutions of the engine. The piston rises, even when negative pressure is small, until it reaches the stop 27l on the upper end of rod 25, at which moment, the

inlet 13 has reached its Vnormal width, and the spring 26 becomes operative, so that the regulating piston rises further only when negative pressure increases still more.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is tobe performed, I declare that what I claim is 1. In a carburetor; a fuel chamber, a floating piston .thereabove; a cup supported by the piston for movement therewith and having its lower portion submerged in the fuel in said chamber and its upper portion opening above the level of the fuel; an atomizing tube rigidly connected to the bottom of the piston and projectingI at its lower end into said cup below the level of the fuel-v and provided at the latter end with an air inlet; and a fuel inlet at the bottom of said-cup and extending into said tube, said inlet being controlled by the movements of the piston.

2. In a carburetor, a fuel chamber; a floating piston thereabove; a cup supported by the piston for movement therewith and having its lower portion submerged in the fuelin said chamber and its upper portion opening above the level of the fuel; an atomizing tube' rigidly connected to the bottom of the piston and projecting at its lower end into said cup below the level of the fuel and provided at the latter end with an air inlet;

. fuel supply means at the bottom of the cup let at its upper portion; a floating piston in the casing for directly controlling the outlet;

an atomizing tube rigidly connected tothe piston and roviding an internal mixture passage whic opens at its upper end through the side wallof the piston for communication with said outlet and has an air inlet at its lower end, said passage also having an opening in its top wall for transmitting engine suction to a point above the piston so as to control the position of the latter exclusively by such transmitted suction.

4. In a carburetor, a fuel chamber; a cylindrical casing on said chamber and provided at its lower portion with an air inlet and at its upper portion with an outlet for the carbureted mixture; a floating piston in said casing for directly controlling said outlet; a tube rigidly secured to said piston and providing an internal passage for conveying a mixture of fuel and air to the outlet, said tube having an air inlet at its lower end; a cup supported by the piston and having its lower portion submerged in the fuel in said chamber and its upper portion opening above the fuel level, said tube having its lower end projecting into the cup below the fuel level: and means controlled by the movements of the piston for supplying fuel in regulated quantity to the cup and the lower end of the tube to undergo atomiza-tion in said tube by the air entering thereinto through the air inlet of the tube.

In testimony whereof I affix my signature.

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