US1771530A - Carbureting device - Google Patents

Description

July 29, 1930. w. A. EDWARDS GARBURETING DEVICE Filed Sept. 13, 1925 Patented July 29, 1930 r UNITED STATES PATENT OFFlCE.

Application filed September 13, 1923. Serial No. 662,584.

The purpose of this invention is to prvcntion is that the conditions at the two venvidean improved construction of fuel feedturis aflcctingthe Capacity of the air flow ing device forinternal combustion engines, for taking liquid fuel from the nozzle are especially adapted for the purpose of causing different, so that equal air How may take unsthe fuel mixture and quantity drawnby the equal quantities of liquid fuel at the two 55 engine suction to be automatically more pernozzles respectively. fectly than heretofore adapted to the require- In the drawings A represents a main fuel mom of the engine at its different speeds, as tank which may be at a low level with rewhen idling and when operating at high spect to the engine intake. B represents a speed under load. float chamber positioned for being supplied 0 In the drawin s: with liquid fuel by gravity from the main Figure '1 is a iagraminatic elevation for tank, A. C is fuel mixture conduit leading showing the several elements of the mixture to the fuel intake pipe and thence to the en- -in their relative positions and in relation to gine intake.

thefioat chamber or other constant level de- From the float chamber, B, liquid fuel is vice to the main fuel tank. delivered through two pipe branches, D and Figure 2 is a horizontal section, axial with D'., to separate venturis C and G situated respect to the fuel mixture conduit and liquid successively in the fuel mixture conduit fuel ducts and nozzle therein. which has its air intake at C where it may Figure 3 is a detail elevation showing a be provided with an anterior throttle, E, conmodification in respect to the relative posinected in any usual manner, (not shown), tions oftwoventuris in the fuel mixture confor operation at will or automatically, acduit and the fuel ducts discharging therein. cording to the conditions of service.

This invention is adapted for use in con- The differentiation between the venturis nection with a low level main fuel supply and the relation of the fuel nozzles thereto tank, serving to dispense with any additional may be effected by several different means, fuel liftingmeans, as may be understoodfroni separately or in conjunction; for itis well the diagrammatic elevation, Figure 1; but its understood that the point or area of greatest distinguishing characteristic is independent depression in a venturi through which an air of the capacity of the device for lifting the flow is produced, is always somewhat beyond fuel; and it may be employed regardless of the point of greatest constriction of the venthe function of fuel lifting. The diagramturi and varies in respect to its exact location niatic views, however, are designed to illusaccording to the angle of taper of the venturi trate the invention applied under conditions passage at the discharge side of the constric- 5 and in a manner to render the apparatus option, and according to the velocity of air flow erative as a fuel lifter,.independently of. its through the venturi throat; and that with primary function relative to lmpression. a given engine action drawing in a given The first characteristic feature of the inquantity of air, the velocity at the constricvention consists in the provision of means for tion is proportional to the cross-sectionalarea causing the suction of the engine to operate at the constriction. for drawing the liquid fuel into the fuel mix- One differentiation is therefore obtained by ture conduit through two separate venturis, locating the points of fuel discharge from the venturis being successively positioned in the nozzles al and d in the two venturis re- .the fuel mixture conduit so that the air drawn spectively at points in the respective venturis 5 in for the fuel mixture traverses both venwhich are different in relation to the low turis, one after the other, and may take in pressure areas of the venturis at an assumed a charge of fuel at either or both of the venengine speed. As illustrated in the drawturis from the nozzle discharges in them re ings, the discharge nozzle d of the fuel duct spectively. D in the venturi C is located at what is a A second characteristic feature of the inintended to be understood as the point of greatest depression in that venturi resulting from a certain assumed velocity of air corresponding to a certain engine speed and throttle opening; and the ischarge nozzle d in the venturi C is shown positioned at a more advanced point in the latter venturi. The assumed engine s eed and throttle opening which roduces t e lowest depression in the venturi C at the point of the nozzle al will not produce the lowest depression in the venturi C at the point of the nozzle d in that venturi 'but a different engine speed and throttle opening which will rod'uce a maximum depression in the venturl C at the point of the nozzle 01 will not produce the conditions for maximum proportional fuel discharge at the nozzle 11 in the venturi C. A proper relating to each other of the two venturis and their respective fuel nozzle positions will cause the variation in efiiciency of each assembly, of venturi and nozzle to be compensated and complemented by the variation in the opposite direction of the efliciency of the other assembly.

In addition to the above described means of differentiating the capacity of equal air flow to produce liquid fuel flow, or instead of these means, such differentiation may be effected by differentiating the contour of the venturis in axial section, as may be seen by comparison of the venturis, C and C the former being more constricted than the latter.

A third means of differentiation may consist in locating the venturis at different levels with respect to the constant level chamber or float chamber, as seen in Figure 3 in which the two venturis are postioned successively in an upwardly extending portion of the fuel conduit. The venturi, C, which has a larger throat or less constriction, and which has the nozzle at the advanced point, being at a higher level than the venturi, C, so that equal air flow through the two venturis independently of the difference in the proportions of the venturis and the relation of the fuel nozzle thereto, will cause less fuel to be drawn through the venturi, C, than the venturi, C

All of the several means above described of differentiating he two venturis and fuel connections thereto in respect to the capacity of air flow for producing the fuel flow, are exemplified in the construction and arrangement of Figure 3.

The reason for and importance of differentiating the means affecting fuel discharge at the two venturis, arises from the fact that with given proportions of venturi and given relation of the fuel discharge to the venturi constriction, up to a certain point the fuel flow, increases with the suction which causes the air flow, and therefore with the engine speed and opening of the throttle. This certain point is that at which the skin friction of the air at the venturi throat operates as an offset, and revents further increase of fuel fiow, or re uces it ultimately to a ne ligible amount. I The less the constriction of t e venturi, and the farther advanced the nozzle or fuel discharge mouth is beyond the venturi constriction, the greater may be the air velocity due to the engine s eed and throttle opening, without passing t e point at which increase of velocity ceases to produce increased fuel flow. If only one fuel discharge is provided at only one venturi, given proportions and relations of the fuel discharge mouth to the venturi throat will be operative for properly proportioning the fuel mixture, only through a limited range of engine speed and thrott e opening; but by providing two fuel discharges, differentiated as to capacity of air flow to produce fuel flow, it is possible to so differentiate them that as the air velocity due toengine speed and throttle opening passes beyond the capacity of one of the venturis and fuel nozzle therein to respond proportionately in respect to fuel flow, the sta e of responsiveness of the other is reache with some overlap of the decline of responsiveness of the first and growth of responsiveness'of the second; and thus the maintenance of proper proportions of air and fuel in the fuel mixture is effected automatically throughout a wide range of engine speed and tiation of the two fuel discharges the entire range from idling speed of the engine to maximum'speed under load, may be covered 7 with proper proportioning of fuel mixture.

It may be understood that the parts above described are dimensioned so that the fuel mixture as delivered beyondthe second venturi will be too rich for efficiency under conditions of open throttle and consequent high engine speed under load. And under these conditions additional air will be taken into the mixture at an air inlet between the second yenturi and the connection with theintake manifold. This may be understood as indicated in Figure 1 by the showing of a fuel mixture conduit, C, discharging in a larger conduit, G, which constitutes the fuel intake connected to the intake manifold of the engine and having a venturi, G at whose constriction the fuel mixture conduit, C, discharges. And it will be noted that, asshown in this figure, the air inlet between the second venturi and the connection to the manifold, there is provided a venturi, G through which the fuel mixture conduit, C, discharges, and immediately anterior to which there is provided the air inlet mentioned above as located between the second venturi and the in take manifold connection. At this air inlet there is provided a spring-controlled valve, G for determining, by the resistance of the spring to the opening of the valve, the stage of suction at which additional air will be admitted. This valve will be opened for adthrottle opening; and by judicious difierenmitting such additional air proportionally to the excess of the suction above the predetermined degree for which the spring is adjusted.

I claim 1. A carbureting device for internal combustion engine comprising in combination with a fuel source in which the fuel is maintained at a substantially constant level, a fuel mixture conduit having an initial air. inlet and comprising two venturis consecutively positioned in the course thereof both antecedout to any outlet or additional air inlet; the discharge mouth of the first venturi being registered with the entrance mouth of the second venturi without material reductionof flow capacity of the passage between the venturi constrictions, means for fuel flow from said source comprising connections for discharge of the liquid fuel in the two venturis respectively, the forms and dimensions of said venturis and the relation thereto of the points of discharge of said fuel connection being different, the differentiation of location of the fuel discharge openings relatively to the constrictions of the respective venturis and the differences in the form and dimensions of said respective venturis operating to cause an increase of the ratio of the fuel flowto the air flow at one of said venturis, due to change of the throttle opening and the engine operation, to be concurrent with the decline of said ratio at the other venturi.

2. In the construction defined in claim 1, one of said fuel discharge openings being at a higher level than the other.

3. In the construction defined in claim 1, one of said venturis having its constriction of greater diameter than the other.

4. In the construction defined in claim 1, the two venturis being at different levels.

5. In the construction defined in claim 1, the two venturis being at different levels, the one which is at the higher level having its constriction of greater diameter than the other.

6. In the construction defined in claim 1, the two venturis being of different diameters, and the openings for fuel discharge thereinto being at different levels.

7 A carbureting device for internal combustion engines comprising in combination with a fuel source in which the fuel is maintained at a substantially constant level, a fuel mixture conduit having an initial air inlet and containing at least two air flow accelerating cross sectional reductions consecutively positioned in the course thereof antecedent to an additional outlet or additional air-inlet, whereby the entire air current is delivered from each preceding to each suceeding cross sectional reduction; means for discharge of the liquid fuel in the conduit proximate to said cross sectional reductions respectively, the dimensions of said cross sectional reductions being different, the differentiation of location of the fuel discharge openings relatively tothe degree of constriction of the respective cross sectional reductions and the differences in the dimensions of said reductions, being calculated and arranged as described for operatin to cause an increase of the ratio of the fue flow to the air flow at one of two consecutive cross sectional reductions due to the change of the throttle opening and engine operation to be concurrent with the decline of said ratio at the other of said consecutive reductions.

In testimony whereof, I have hereunto set mfy hand at Chicago, Illinois, this 10th day 0 September, 1923.

\VM. A. EDWARDS.

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