US2447264A

US2447264A - Carburetor

Info

Publication number: US2447264A
Application number: US255676A
Authority: US
Inventors: Jr Guy E Beardsley
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1939-02-10
Filing date: 1939-02-10
Publication date: 1948-08-17
Anticipated expiration: 1965-08-17

Description

Aug. 11, 1948. G. E. BEARDSLEY, JR Y 2,447,26

CARBURETOR I '3 Sheets-Sheet 1 Filed Feb. 10, 1939 INVENTOR. 'qffieardv Jr:

dRNEY.

Aug. 17, 1948. G. E. BEARDSLEY, Jk

CARBURETOR 3 Sheets-Sheet 2 Filed Feb. 10, 1939 INVENTQR. 60 ffieardr/eyJ/r 6k A ORNEY.

Aug. 17, 1948. e. E. BEARDSLEY, JR 2,447,254

CARBURETOR 3' Sheets-Sheet 3 Filed Feb. 10, 1939 INVENTOR. 60 1E fiM/dI/e JA' Patented Aug. 17, 1948 Guy E; Beardsley,

signor to Bendix In, West mimosa, coma, as-

A'viation Corporation; South Bend, 1116., a corporation of Delaware "Application Februarylo, 1939, Serial No. 255,676 -23 Claims. (01. 261-41) My invention relates to carburetors.

My invention has among its objects to provide an improved carburetor of the economizer type wherein the mixture strength is controlled in an improved manner. A further object of my invention is to provide improved means for controlling the richness of the fuel mixture in such a carburetor in such an improved manner as,

while obtaining the desired results as regards economy under normal operation, also suppresses detonation while operating efficiently over a wider range of power outputs, and obtaining improved engine operation while operating in the economizer range, 1. e., at high power outputs.

A still further object of my invention is to provide such an improved carburetor construction having the advantages aforesaid and further utilizing as a mixture controlling factor, pressures varying proportionally with and in response to variations in the quantity of air flow ing to the engine, and thereby providing a more accurate measure of the power output than obtainable in prior devices.

'Still another object of my invention is to provide such an improved economizer-equipped carburetor which is especially adapted to use in supercharged engines, and particularly in airplane engines, and to maintain an improved control of the enrichment flow throughout high engine power output conditions regardless of changes in. supercharger speed, or supercharger pressure rise or engine loads within the economizer range.

Another object of my invention is to provide such an improved carburetor wherein the economizer is controlled by the differential of throat and scoop pressures in such manner as to be operated proportionally with and in response to changes in the same differential of pressures controlling the fuel inlet valve of the carburetor, and thereby effect further opening movement of said valve to enrich the mixture, in such manner that it is thus made possible by accurately measuring the air flow and utilizing this differential varying with the measured air flow to the engine, as the determinative factor controlling economizer operation under high engine power output conditions, thereby, in effect, to make the horsepower output of the engine this determinative factor.

Still further objects of my invention are to provide an improved carburetor wherein the main fuel flow controlling mechanism, which acts to maintain a constant fuel-air ratio, and my improved economizer are separate and both are operated by variations in air How, and wherein, in the economizer range, the economizer causes said main fuel flow controlling mechanism to be operated through an increasedrange of opening movement; all 'in such'manner that the main fuel flow controlling mechanism ,notonly acts under all engine power output conditions to" provide a known constant fuel-air ratio varying with the air flow, butis also caused to be additionally actuated in an opening direction when ever the air flow controlled economizer comes into operation, in such manner as to add to the inlet valve movement maintaining a constant fuel-air ratio mixture, a further fuel enriching increment varying as a function of air flow under high engine power output conditions. Other objects are to provide an improved carburetor of the above type wherein, while obtaining the above advantages, the inaccuracies of metering through a variable orifice are also eliminated or confined to a small percentage of the total flow, and one wherein it is made possible for the operation of the carburetor to be readily modified as desired to meet the varying requirements of diflerent engines, by making possible an independent adiustment of or a mere substitution of a precalibrated, economizer element or elements,

' without disturbing the main fuel control mechanism, and a like independent adjustment or mere substitution for the main fuel flow controlling mechanism when only modification of the latter is required.

Still another object of my invention is to provide such an improved economizer-equipped carburetor adapted to apply the above differential controlling pressure to control the metering of either float type carburetors or fuel pressure type carburetors of various forms while being particularly adaptedto utilize this improved differential pressure control to control the actuation of diaphragm actuated type fuel inlet'valves of such last-mentioned carburetors.

A still further object is to provide such an improved economizer-equipped carburetor wherein the differential pressures at varying power outputs may be automatically varied to compensate for changes in altitudes, while also maintaining the desired relationship between the main and enrichment flows.

Other objects and advantages of this invention will be apparent from the following detailed description of several desirable embodiments thereof,-considered in connection with the ac- 3 illustration only, and not intended to define the scope of the invention, reference being had for that purpose to the subjoined claims.

In the drawings, wherein similar referencecharacters refer to similar parts throughout the several views:

Figure l is a vertical, diagrammatical, sectional view of a carburetor or charge forming device embodying the present invention;

Fig. la is a like detail view of a modified struction;

Fig. 2 is also a vertical, diagramxnatica l, sectional view of a different carburetor embodying a modified form of the invention, and

Fig. 3 is a vertical diagrammatical section of a carburetor embodying a still further modified form of the invention.

Referring to Figure 1, it will be observed that a carburetor body section I8 carries an air inlet passage or scoop I2 and forms an induction passage I4. The induction passage is provided with a venturi I6, and a fuel discharge nozzle I8 is positioned somewhere near the section of maximum restriction of the venturi I6.

The induction passage I4 is controlled by a throttle valve 28, which may be manually operated from the pilot's or operator's compartment by means of a'rod 22. The body section I8 of the carburetor is provided with a flange 24, by means of which it may be attached to the intake manifold of an engine or to the inlet of a supercharger driven by the engine.

Fuel is supplied to the fuel discharge nozzle I8 by means of a fuel passageway 26, which communicates with a fuel reservoir 28. The fuel level in the reservoir 28 may be maintained at a substantially constant level by means of a fuel inlet passage 38, which is controlled by a valve member 32 actuated by means of a float mechanism 34. The flow of fuel from the reservoir 28 to the fuel passageway 26 is controlled by a restricted passageway, herein a stationary metering or measuring orifice 36 of fixed dimensions, and by a controlled orifice 38.

The orifice 38, communicating with the passageway 26, is controlled by an economizer valve 48. The valve 48 is carried by a diaphragm mechanism 42, and is yieldingly urged downwardly to close the orifice 38 by means of a spring 44 nested in a chamber 46. The chamber 46 is closed except for a passageway 48, communicating with the fuel passageway 26, intermediate the fuel discharge nozzle I8 and the fuel reservoir 28. The chamber 46 and the upper surface of the diaphragm 42 are thus subjected to the pressure at a restricted section of the venturi I6, as transmitted through the fuel discharge nozzle I8 and the passageways 26 and 48.

The fuel reservoir 28 and the lower surface of the diaphragm 42 are subjected to the air pressure existent in the air inlet or scoop I2, by means of a passageway 58 interconnecting the fuel reservoir 28 through an annular passage 58a connected to tubes or passageways 52 formed in the air inlet or scoop I2.

The diaphragm 42, which actuates the economizer valve 48 controlling the orifice 38, is thus at the restricted section of the venturi I6, urging it in a direction to open the valve 38. When this differential of fluid pressure creates a force willcient to overcome the force of the spring 44, the

valve 48 opens the orifice 38 an amount proportional to the variation in fluid pressure, while opening of the valve 48 proportionally with and in response to changes in air fiow, also causes the float 34 to open the valve 32 further in such manner as to increase the fiow through the latter.

It will be noted that the pressure at the restricted section of the venturi I6, transmitted to the upper surface of the diaphragm 42 through the passages 26 and 48, is transmitted part of the Way through the fuel in the passageways; however, the fuel level may be lowered in the passageway 48 by an amount equal to the suction at the restricted section of the venturi. It will be understood that, while the fuel in the passage 48 is shown at the same level as in the float chamber 28, this is due to the closed position of the throttle 28 illustrated, and that when the throttle is opened, the level of the fuel in passage 48 will drop as the throttle opens; fuel flow, of course, then continuing through passage 26 and the throat pressure being transmitted to the diaphragm 42 through the fuel in the passage 26 and the air in the passage 48.

It will thus be observed that with the Venturi suction and air scoop pressure acting on the opposite sides of the orifice 36, the fuel nozzle I8 is always supplied with fuel during cruising under the control of the fioat34 and valve 32 through the restricted passageway 36 in such manner that a predetermined fuel-air ratio is maintained. These forces continue to act throughout the operation of the economizer valve 48' but the valve 32 is caused to open further to supply an additional quantity of fuel when the air scoop pressure and the Venturl suction reach a predetermined differential of pressure sufficient to open the valve 48. It will also be observed that the differential of pressure acting across the orifice 36 varies with the differential of pressure causing operation of the valve 48 and that once the economizer valve 48 has opened to permit fiow through the orifice 38, the fuel fiow in any given position of the valve 48 would vary in the same proportion as the quantity of fuel fiowing through the orifice 38, i. e. in proportion to the square root of the differential of pressures on opposite sides of the orifice; this same condition holding true for all positions of the economizer valve 48, until the differential of the pressures acting across the diaphragm 42 drops to such a value that the spring 44 urges the valve 48 to completely close the orifice 38, whereupon the previously described control during cruising is resumed.

In Figure 1a, a modified construction utilizing the same economizer valve 48 is shown. In this construction, instead of the passage 48 being connected to the passage 26, the passage 48 is connected by a passage 48a to an annular passage 48b which, in turn, is connected through radially located passages 480 to a restricted portion, of the venturi I6. Further, it will be observed that in this construction, a bleed passage 28a is connected between the passage 26 and a passage 26b which is, in turn, connected by a restriction 260 to an annular passage 58a. In this construction, a higher suction effect is obtained for operation of the valve 48, while the bleed connection provided will function in a well-known manner to emulsify the fuel supplied through the nozzle I8.

pressures in the throat and constant fuel air ratio, and my economizer mechanism are actuated by pressures varying proportionally with and in response to changes in said quantity, it is possible to control the enrichment of the fuel mixture in the economizer range with far greater accuracy in accordance with known engine performance requirements than has heretofore been possible. Since I find that the air flow to the engine, while varying over a wide range at different power outputs, maintains a close relation -to the brake horsepower output, in my improved mechanism I utilize these variations in air flow as a controlling factor in fuel enrichment. More particularly, I utilize as the controlling factor for the economizer the differential relationship between the suction produced in the throat of the venturi and the pressure developed in the scoop, which differentia1 increases in proportion to the square of the air flow through the venturi. Thus, it will be observed that the differential pressure resulting is such as to make it possible to obtain a force exerted on a diaphragm in one direction which bears a square relationship to the air flow through the carburetor, and thereby obtain a correctly proportionedmixture enrichment when the diaphragm is used to control the supply of additional fuel. Moreover, it will be recognized that it is possible, by means of automatic altitude compensating devices, to have such a force exerted by the diaphragm proportional to the square of the mass air flow (weight per unit of time) at all altitudes, in suchmanner as and in response to changes in 6 open ends subjected to the pressure of the air entering the inlet passage or scoop;

The induction passage I3 is controlled by a manually actuated throttle valve 23, controlled y the operator of the craft, It will be observed that in this embodiment of the invention, fuel may be admitted into the induction passage i3 to operate theeconomizer valve by balancing it against a spring of any chosen force and rate. As a result of this construction, it will further be evident that it is possible to. approach very closely'the conditions established from engine tests as more nearly approaching ideal engine fuel requirements, not only as regards actual economy of fuel consumption, butalso as regards increased range of economical operation at lower power outputs without detonation, all while continuing to suppress detonation'and obtain' =safe operation and improved efficiency through-operation at higher mean effective pressures.-

"The embodiment of the invention illustrated on Figure'2 shows the same applied to a certain Bendix type of diaphragm operated carburetor having a body section 9, an air inlet passage or scoop ll,"and an induction passage 13. A venturi'ji is positioned in the body section 9 and is provided with an annular passageway I'I communicating with a restricted section of theventurijlby means of a plurality of apertures l9. The annular passageway I1 is thus subjected .to the fluid pressureexisting at a restricted section of the venturi IS. A plurality of passageways 2|, positioned in the air inlet passage or scoop II and only one of which is shown, have their posterior to the throttle valve 23 by meansof a fuel discharge nozzle 25.

Fuel under pressure may be supplied to this carburetor by means of a fuel conduit 21. Entry of fuel into the carburetor may be controlled .by a valve casing member 29 having apertures 3| therein. The apertures 3| may be controlled by a valve member 33 of a well known type normally balanced by opposing pressures of the unmetered fuel flowing therethrough, and carried on and actuated by a valve stem 35. Fuel under pressure is thus admitted from the conduit 21, through the apertures 5! controlled by valve member33, into a, chamber 31, separated from a chamber 39 by means of a diaphragm assembly 4| carried by'the valve stem 35. Fuel may be transmitted from the chamber 31 to the chamber 39 by means of a restricted orifice 43, corresponding to the orifices 36 hereto described from whence it is delivered to the fuel nozzle 25 by way of a fuel conduit 45. The rate of fuel flow through the orifice 43 is dependent, in part, on the variation in fuel pressure in chambers 51 and 39, which are separated by the diaphragm valve. stem 35 may be actuated by a diaphragm- 5l, separating chambers 53 and 55.

The chamber 53 is connected by means of passageway 51, chamber 59 and passageway 6i with the annular passageway l'l, subjected to the pressure at a restricted section of the venturi through the apertures l9. The passageway ii is provided with a restriction 63.

The chamber 55 is connected by means of passageway 65, chamber 61' and passageway 69 to the passageways 2|, subjected to the pressure of the air at an unrestricted section of the air inlet passage or scoop I I,

It will'be observed that the passageways 9I- Y and 69 are interconnected by means of a restricted orifice ll controlled by a valve 13. The valve I3 is adapted to be actuated to open and close the restricted orifice II by means of a bell crank 15 operably connected to and actuated by an aneroid 11. The aneroid 11 may preferably bepositioned in the air inlet passage or scoop H, and thus subjected to variations in temperature and barometric pressure in accordance with variations in altitude. It will be noted that, as the pressure decreases with increasing altitude, the aneroid expands to the left, thereby actuating the bell crank 15 to withdraw the valve 13 from the orifice II to permit air to flow from the passage 69 to the passage 6| to reduce the differential of fluid pressure between these two passages, and also between the chambers 55 and 53, which actuate the fuel inlet valve 33.

The

fuel chambers

31 and 39 may be separated from the regulator chambers 53 and II by 7 means of a diaphragm 19 carried by the valve stem 35 to prevent leakage of air or fuel from one group of chambers to the other. Further, it will be noted that chamber 39 is connected by a passage 39a to a bottom chamber 39b which is separated from chamber 55 by a diaphragm 390 of the same area as diaphragm 19 in such manher as to equalize the pressure above and below these diaphragms so as to balance out their effect on stem 35.

The operation of this device is as follows. When the unit is mounted on an aircraft or in any other installation wherein it may be used, a quantity of air is supplied to the air inlet passage or scoop The air pressure at the ends of tubes 2| is transmitted through the passageway 69, chamber 61 and passageway 65 to chamber 55 of the regulator unit to urge the diaphragm connected to the valve stem 35, upwardly, as viewed in Figure 2, to open the fuel 4 admission valve 33 to admit fuel from the fuel conduit 21 to the chamber 31; a constant fuelalr ratio being obtained as is well known in such pressure type carburetors.

The pressure of air in chamber 61 is exerted on the upper surface of the diaphragm 49 to help in urging the economizer valve 41 downwardly against the resistance of a suitably loaded spring 3| nested in chamber 59, to open the auxiliary fuel orifice 45a.

The greater portion of the air entering the air inlet passage or scoop I passes through the venturi l5, and a suction or reduction in pressure is developed in the annular passageway IT by means of the apertures l9 in the Venturi I5. This Venturi suction is transmitted through the passageway 5|, restriction 63, chamber 59 and passageway 51 to the chamber 53 to exert a force on the diaphragm 5| tending to raise the valve stem carrying the fuel admission valve 33, to

Since the chamber 59 is subjected to Venturi suction, the lower surface of diaphragm 49, which actuates the economizer valve 41 controlling the auxiliary fuel orifice a, is subjected to a suction force tending to urge the diaphragm downwardly to compress the spring 8| and open the auxiliary fuel orifice 45a, to admit an increased quantity of fuel to the engine.

It will be noted that since fuel under pressure is supplied to the chamber 31 and is by-passed around the diaphragm 4|, by means of the orifices 43 and 45a, to the chamber 39, the diaphragm 4| is subjected to a force tending to close the fuel inlet valve 33; The pressure in chamber 31 must be greater than the pressure in chamber 39 in order for fuel to flow through the orifices 43 and 45a.

The fuel inlet valve 33, carried by the valve stem 35, is thus actuated by air scoop pressure in chamber and Venturi suction in chamber 53. When the force resulting from these two pressures exerted on the diaphragm 5|, overcomes the force exerted by the variation in fuel pressure in

chambers

31 and 39, urging the valve 33 toward the closed position, the diaphragm assembly moves upwardly, as viewed in Figure 2, to open the fuel inlet valve 33 to admit fuel to the chamber 31.

The pressure differential between

fuel chambers

31 and 39, which is the force across the metering orifices 43 and 45a, is determined by in chambers 53 and 55 acting on diaphragm 5|.

As the density of the air decreases due to increase in altitude, the aneroid 11 actuates the valve 13 to open the restricted orifice 1|, interconnecting the passageways GI and 59, to variably reduce the suction in passageway BI and in chambers 59 and 53. The force urging the regulator diaphragm 5| upwardly to open the fuel inlet valve 33 is thus affected by variations in altitude and by proper adjustment of the aneroid, linkage and orifices, this force may be held at substantially a constant value for any chosen mass air flow regardless of changes in atmospheric density.

The auxiliary fuel orific 45a, which delivers an additional quantity of fuel to the engine under certain operating conditions, is, as pointed out above, controlled by the economizer valve 41 and the diaphragm 49. When the force of air inlet pressure transmitted to the chamber 61 and the force of the Venturi suction transmitted lower surfaces of the diaphragm 49 are sufficient to overcome the resistance of the spring 8|, urging the valve 41 to close the orifice 4511, the valve 41 is moved downwardly, as viewed in Figure 2, to open the orifice 45a to admit an increased quantity of fuel to the engine. It will be noted that the force exerted on the diaphragm 49 to actuate the valve 41 is compensated for variations in altitude by means of the orifice 1|, interconnecting passages 69 and GI, the aneroid controlled valve 13.

In this form of my invention, it will be observed that not only do the variations in the quantity of the air flow to the engine, represented by the differential between th throat and scoop pressures, control the economizer valve 41, but the latter valve also controls the action of the fuel inlet valve 33 in the economizer range to sllperimpose an enrichment flow on the constant fuel-air ratio main flow. Here it will be noted that pressures from the throat and scoop also act on opposite sides of the diaphragm 5| carried by the stem 35 of the fuel inlet valve 33, to control the position of the latter and the fuel pressure on the opposite sides of the diaphragm 4| at the same time that the economizer valve 41 also acts to control the fuel pressures on the opposite sides of diaphragm 4| and the consequent supply of fuel to the nozzle 25. Thus, due to the provision of my improved economizer valve 41, it is made possible to obtain a wholly new and more accurate control of the fuel valve 33 in accordance with engine requirements through modifying the control effected by the latter valve, as a result of the provision of the additional orifice 45a controlling the flow inthe fuel line leading to the nozzle 25 and also controlled by the valve 41. More particularly, it will be observed that as the differential pressure acts on the diaphragm 5| to open the valve 33, this same differential pressure is acting on the economizer valve 41 to open the orifice 45a. Further, as this orifice is opened, flow downward through the latter increases the pressure beneath the diaphragm 4| and thereby simultaneously correspondingly decreases the pressure above this diaphragm, in such manner as thus temporarily to unbalance the valve mechanism including the valve 33 and open the latter to increase the rate of fuel flow through said valve and thereby torestore thfe. Attention is moreover directed to the fact that in my improved economizer construe tion, the above pressure differential controlling" balance.

the economizer valve 41 is controlled bythe anelactuated by raid in such manner as thereby to provide automatic compensation for altitude byautomatically varying, the differential of pressure acting on both the valves 41 and 33. The embodiment of the invention illustrated in Figure 3 is similar in many res ects to that illustrated in Figure 2, a generally similar pressure carburetor adapted to obtain a constant fuel-air ratio, being illustrated and like parts separated by a diaphragm I9I, may be employed to assist in actuating the fuel inlet valve I33 in such manner as to enable the latter to function as an economizer. In this construction, I increase the ratio of the fuel-metering head between the chambers I31 and I39, across the fuel orifice I43 corresponding to orifices 36 and 43 previously described, to the air metering head differential between air scoop III and Venturi suction at chamber II1. Downwardmovement of the diaphragm I9I is limited by spaced stops I93 positioned in the chamber I89. The diaphragm is centrally apertured to pass over the valve stem I35 and engages an abutment I95, when moved upwardly by fluid pressure acting on the exposed surface of the diaphragm -I9I outside 'of a pair of sealing bellows I91 and I99 positioned to engage the upper and lower surfaces of the diaphragm I9I in the chambers I 81 and I89 respectively. The diaphragm I 9I is yielding y ur downwardly toward engagement with the stops I93 by means of a spring I98,

"The lower end of chamber I89, as viewed in Figure 3, is.clo'sed by a diaphragm I98, which forms the upper portion of a chamber I94. The

chamber I94 is interconnected by means of a fuel duct I92 with the metered fuel chamber I39, so that the pressure of the fuel in cham-.

bei- I39 is balanced against the pressure of fuel in chamber I94 by means of the equal area diaphragms I19 and I96 as described in connection with Figure 2.

The chamber I81 is connected by means of a passageway I90 with the Venturi suction as transmitted to th chamber I53 by means of the passageway I8I. The chamber I89 is connected by means of afpassageway I88 with the air inlet or scoop pressure as transmitted to the chamber I55 by means of the passageway I69.

' In the operation of this device, when the total force of the air scoop pressure in chamber I89 and the Venturi suction in chamber I 81 exert sufiicient upward force on the diaphragm I! to compress the spring I98, the upper surface of the diaphragm I9I engages the abutment I95, and thereafter exerts a force which, in addition to the force exerted on thediaphragm II by Venturi suction as transmitted to chamber I53 and air scoop pressure as transmitted to chamber I55, urges the fuel inlet valve I33 toward the open position to admit fuel to the fuel chamber I31. When the force urging diaphragm I 9| upwardly drops below the downwrd force exerted by'the spring I98, the diaphragm I9I is moved' valve member I13, controlling the restricted orifice I1 I, maybe employed to compensate the fluid pressures in chambers I53 and I55 and I81 and I99 for variations in altitude. If desired, however an altitude control feature may be employed to compensate the forces acting on only one of the diaphragm I5I and I9I.

In this construction, it will be observed that substantially the same results are'obtainable as described above-in connection with .the construction shown in Figure 2, both as regards control of the pressure fuel inlet valve, here indicated at I33, and also as regards the automatic compensation for altitude by the aneroid here indicated at I11. However, here it will be noted that the different pressures in the air passage means act directly on the diaphragm of valve I33 rather than indirectly through an additional valve, as in Figure 2, wherein the diaphragm of valve 41 is acted on by these different pressures and, in turn, controls the valve 33. Further, it will be observed that these results are obtained while utilizing only this valve I33 and without requiring the use of any additional valve such out of engagement with the abutment I95 and I toward engagement with the stops-I93. Thereafter, the fuel inlet valve I33 isv controlled only by the diaphragm \I5I, as.pointed .out above.

It will be noted that the'aneroid actuated as the economizer valves 49 and 41 heretofore described, and while requiring only the provision of the improved spring controlled diaphragm I9I which is itself acted upon by the differential pressures in proportion to those in the scoop III and the throat of Venturi I I5.

In all illustrative forms of my invention, it

will also beevident that, while during normal cruising the main fuel flow is through a fixed main orifice and varied in proportion to accu-v rately measured variations in air flow, the movement of the separate economizer diaphragm (42 in Figures 1 and 1a, 49 in Figure 2, and HI in Figure 3), which is stationary during normal fuel flow and movable only under high power output conditions, causes a greater than normal openin'g movement of the valve which controls the main fuel flow (32 in Figures 1 and la, 33 in Fig- -ure 2, and I33 in Figure 3). This further opening movement of this main fuel valve is controlled by the same variations in air flow actuating said valve to effect the main fuel fiow, and this enrichment flow is superimposed on the fuel component of the main fuel-air ratio with both the enrichment flow and this fuel' component thereafter each continuing to vary independently with changes in air flow. The above action also takes place irrespective of whether the control of this main fuel valve is effected indirectly through the fuel acting on the valve actuating mechanism, as in Figures 1, 1a and 2, or directly mechanically on said mechanism as in Figure 3, and also irrespective of whether the additional fuel is delivered through a fixed. main orifice and variable economizer orifice as in Figures 1, 1a and 2, or through a single fixed main orifice as in Figure 3.

As a result of my invention, it is also made possible in all forms thereof to provide fuel metering orifice means for the main fuel flow which are fixed against orifice area varying movement in response to changes in engine operation, and

whereby the cross sectional area is maintained constant in such manner that the inaccuracies in the main fuel flow resulting from such changes in areaare avoided at all times. Thus, in Figures 1 and 1a, such a non-variable orifice 38 is made possible,'whi1e a like orifice 43 is provided in Fig. 2, and the single orifice I43 in Fig. 3 is also fixed against movement causing variations in flow therethrough. As a result, it is not only made possible to simplify the main fuel flow orifice structure to the maximum degree, but also markedly to increase the accuracy of the constant fuel air ratio flow therethrough. This last is very important under conditions where the fuel air ratio is of critical importance, for example, enabling cruising lean under conditions where, with the inaccuracies inherent in a variable orifice, cruising rich would Otherwise be required. Further. my improved construction also makes it possible for this same increased accuracy to be obtained throughout the entire range of engine loads, this markedly more accurate main fuel flow continuing to be obtained irrespective of the provision of my air fiow controlled economizer and irrespective of whether the engine is operating under normal load conditions without the economizer or under overload conditions with the economizer in operation. Accuracy of metering when operating under overload conditions with the economizer in operation, is also very important, enabling satisfactory engine operation under conditions impossible with inaccurate metering. Thus, it is made possible, for example, under-critical or emergency overload conditions for airplane engines of high output to attain maximum horsepower despite the fact that engine operation is such that slight variations from the correct amount of fuel will produce either dangerous operation on the one hand, due, for example, to overheating or detonation, or obviously unsatisfactory operation .on the other hand, due, for example, to loss in engine power and engine roughness. Thus, with the enrichment flow constituting only a'fraction of the total fiow, and with the total fiow (Fig. 3), or all but this fraction of the total flow (Figs. 1, 1a and 2), accurately meterable by non-variable precalibrated orifice means, and each of the main and enrichment flows responsive sensitively to the same controlling factor, namely, to variation in the same differential of airflow, an extremely sensitive and accurate fuel supply to the engine is maintained over the whole range of engine performance.

Attention is also directed to the fact that, throughmy improved separate yet cooperating and coordinated air flow controlled controlling mechanism for the normal cru sing and the mixture enrichment flows, it is thus made possible to elimina e or confine to a small percentage of the total fiow, i. e. to the enrichment flow, the inaccuracies of metering through a variable orifice, and thereby obta n a fuel su p y which under all conditions verv closely approximates the requirements for ideal theoretical engine performance. Further, my improvements make it possible for the fuel fiow during economizer operation to be, in effect, divided into two components. one compr sing a known normal fuel flow through a fixed orifice and controlled in response to variations in air flow by the main fuel flow controlling mechanism and which contributes a flow of known fuel air ratio, and the other comprising a known enrichment fiow which is added to the main fuel flow by the separately controlled and operated economizer mechanism. Both are operated in the economizer range by pressures responsive ot variations in air flow, all in such manner that in the latter range the total or enriched flow is accurately controlled by the air flow. Also, each mechanism being separate is accordingly separately adjustable when adjustment is required, each without requiring adjustment of the other. Attention is also directed to the fact that all forms of my improved economizer mechanism also act in the economizer range in the manner of a booster to increase the opening movement of the main fuel flow controlling mechanism, this being accomplished in the forms shown in Figures 1, 1a and 2 by increasing the size of the fuel measuring orifice means through the provision of an additional measuring orifice opened only in the economizer range, and being accomplished in the form shown in Figure 3, by

increasing the force available to operate the main fuel controlling valv through the additional air pressure responsive diaphragm which also acts thereon only in this range. Further, my improvements also make it possible readily to apply my improved economizer mechanism to either float carburetors, such, for example, as illustrated in Figures 1 and 1a, or pressure carburetors such as illustrated in Figures 2 and 3. It also makes it possible to do this without major changes in standard carburetors of either type, or requiring either that the main fuel fiow be upset in the economizer range, or the use of a variable orifice in the main fuel flow, or a common variable orifice for the combined main and enrichment fuel flows, or the provision of both a variable orifice in the main fuel flow only and an additional fuel venturi in the main fuel flow.

In addition to the advantages set forth above, attention is also directed to the fact that in my improved construction th economizer is freed from the objectionable variables affecting the operation of the economizer, and of the engine, which are inherent in superchargers, such, for example, as the variations in engine speed which characterize previous supercharger rise and supercharger discharge pressure operated economizers. Since, as a result of these variables, neither the pressure rise through a supercharger nor the discharge pressure of a supercharger maintains a constant proportionality tothe metering suction or differential between the throat and scoop in the carburetor, the enrichment effected by an economizer of either of these types thus bears no fixed relation to the quantity of air supplied to the engine. In my improved construction, however, the economizer is wholly independent of these. objectionable variables and, since it varies the enrichment proportionally with and in response to changes in the metering suction or differential of throat and scoop pressures, and, irrespective of changes in engine speed, the enrichment accordingly varies proportionally with and in response to changes in the quantity of air flowing to the engine, 1. e. in proportion to engine requirements. Moreover, in my improved construction, my new proportionality of enrichment is also maintained, and by a single aneroid, irrespective of variations in altitude or temperature. Further, my improved proportionality of enrichment is obtained irrespective of whether a supercharger is used or not and, if a supercharger is used, whether the same is located posterior to or anterior to. the throttle.

While the invention has been described with particular reference to a few illustrative embodiments, it is to be understood that many changes may be made in the details of construction without departing from the spirit of the invention as defined by the following claims.

What I claim as new and desire to secure by Letters Patent is:

1. A charge forming device for an internal combustion engine comprising a conduit for supplying air to the engine, a throttle controlling 13 the same, air flow measuring means including venturi located in said conduit upstream of the throttle for setting up a differential in the air pressures at two spaced points in the conduit proportional to the quantity of air flowing through said conduit. a fuel conduit for supplying fuel to the engine, a fuel valve controlling the fiow of fuel through the fuel conduit, a fuel metering orifice in the fuel conduit, means including passages extending from the venturi at said spaced points for establishing a differential in the pressures at spaced points in said fuel conduit on opposite sides of the metering orifice thereby to provide fuel flow at a rate substantiall proportional to air flow, a by-pass around said. orifice, an economizer valve controlling said by-pass, a movable wall operatively connected to said economizer valve, and pressure trans,- mitting means interconnecting the oppositesides of said Wall with one of said conduits at the said spaced points therein 2. The invention defined in claim 1 wherein said means for establishing a differential in the pressures at spaced points in said fuel conduit includes a plurality of diaphragms operatively connected to said fuel valve and responsive to said diiferential in air pressures and to the differential in the fuel pressures on opposite sides of said metering orifice.

3. The invention defined in claim 1 comprising in addition a constant level fuel chamber in the fuel conduit between the fuel valve and the metering orifice, and a float in the chamber for actuating said fuel valve, said fuel conduit discharging substantially at the throat of said venturi and forming one of said passages and a duct leading from the entrance of the venturi to the top of the constant level chamber forming another of said passages. I

- 4. A device for controlling the supply of fuel to an engine comprising a main air conduit for supplying air to the engine, air flow measuring means including a venturi located in said conduit for setting up a differential in the air pressures at two spaced points in the conduit proportional to the quantity of air flowing through Y said conduit, a fuel conduit for supplying fuel to the engine, a fuel valve controlling the flow of fuel through the fuel conduit, a fuel metering orifice in the fuel conduit, means including passages extending from the venturi at said spaced points for establishing a differential in the pressures at spaced points in said fuel conduit on opposite sides of the metering orifice thereby to provide fuel flow at a rate substantially proportional to air fiow, an additional orifice in parallel with said metering orifice, an economizer valve controlling said additional orifice and biased toward closed position, a movable wall operatively connected to said economizer valve, and pressure transmitting means interconnecting the opposite sides of said wall with one of said conduits at the said spaced points therein for opening said economizer valve to enrich the mixture during high power output conditions.

5. A device for controlling the supply of fuel to an engine comprising a conduit forsupplying air to the engine, a throttle controlling the same, air flow measuring means including a venturi located in said conduit upstream of the throttle for setting up a differential in the air pressures I 14 through the fuel conduit, a fuel metering orifice in the fuel conduit for creating a differential in the fuel pressures at two spaced points in the fuel conduit proportional to the fuel flowing through said orifice, means responsive to said airv and fuel differential pressures for controlling said valve to regulate the fuel flow and thereby to maintain the differential in fuel pressures proportional to the differential in air pressures, a icy-pass around said orifice, an economizer valve controlling said by-pass, a movable wall operatively connected to said economizer valve, and pressure transmitting means interconnecting the opposite sides of said wall with one of said conduits at the said spaced points therein.

6. A charge forming device'for an engine having an air conduit, a throttle in the conduit, an air differential pressure creating means in the conduit anterior to the throttle, a fuel conduit receiving fuel from a source and supplying it to the engine, fuel metering means in said fuel con duit for creating a fuel differential pressure in said fuel conduit upon fiow of fuel therethrough, valve means for controlling the flow of fuel through the conduit; a plurality of diaphragms connected to the valve means for operating the same, means for subjecting the diaphragms to the airand fuel differential pressures, an enrichment valve for varying the effective area of the fuel metering means, a diaphragm operatively connected to the enrichment valve, and passages interconnecting the last-named diaphragm and one of said conduits for subjecting the last-named diaphragm to one of said differential pressures,

' said diaphragm operated enrichment valve being inoperative at low values of said one differential pressure corresponding to low power output and being arranged to open when said one differential pressure exceeds a predetermined value corresponding to a relatively high power output'of the engine. t I

7. A charge forming device having fuel supply passage means including metering orifice means fixed against orifice area varying-movement in response to changes in engine operation, air flow passage means including venturi means having a throat and a scoop, a fuel inlet valve in said fuel supply passage means normally balanced by opposing pressures of unmetered fuel being de-' livered to said orifice means, valve w actuating means including a plurality of diaphragms coaxial with said valve and forming movable walls of four chambers for maintaining a substantially constant fuel air ratio and having one diaphragm fixed at its periphery and subjected on opposite sides to air pressures in said throat and scoop and another diaphragm fixed at its periphery and spaced between said first mentioned diaphragm and said valve and subjected on opposite sides to the metered and unmetered fuel pressures on opposite sides of said orifice means, an economizer mechanism for enriching the mixture under high engine power output conditions including a pressure responsive movable wall biased against mixture enriching movement during normal engine power output conditions, and pressure transmitting connections from the opposite sides of said movable wall to two of the said chambers for subjecting the movable wall to a differential in pressures proportional to the differential in the pressures in said throat and scoop thereby to actuate the wall and enrich the mixture when said difierential in the pressures in said throat and scoop exceeds a predetermined value.

an engine comprising fuel supply passage means including a metering orifice fixed against orifice area varying movement in response to changes in engine operation, an air supply passage including means for setting up a differential of pressures proportional to air fiow, valve mechanism including a fuel valve in said fuel supply passage means movable to vary the supply of fuel to said orifice, valve actuating means including a plurality of diaphragms movable with said valve for maintaining a substantially constant fuel air ratio and movable in response to changes in said differential of pressures in said air passage means, one of said diaphragms being subjected to said pressures and another to fuel pressures on opposite sides of said orifice, an economizer means for controlling the operation of said valve actuating means to effect further fuel valve displacement to increase the fuel flow through said fuel supply passage means to enrich the mixture, said economizer means being actuated by a movable wall subjected on opposite sides to two of the pressures to which said diaphragms are subjected having a differential proportional to said differential of pressures.

9. The invention defined in claim 8 wherein said economizer means includes a by-pass around said metering orifice, and an economizer valve in said by-pass biased toward closed position and mechanically connected to said movable wall to be opened thereby under conditions of higher than normal power output.

10. A device for controlling the supply of fuel to an engine comprising an air supply conduit having means therein for creating a differential in air pressures in response to fiow of air therethrough, a fuel conduit having fuel metering means therein for creating a differential in fuel pressures in response to the fuel fiow therethrough, a valve controlling the fiow of fuel through the fuel conduit, means including an aneroid for establishing a modified differential in air pressures proportional to the air mass rate of flow through the air conduit, a plurality of diaphragms operatively connected to said valves and forming movable walls of four chambers, means for subjecting two of the chambers to said modified air pressures and the other two chambers to said fuel pressures, an element for varying the effective area of the fuel metering means and biased against area increasing movement, a movable wall operatively connected to said element, and pressure transmitting means connecting the opposite sides of said movable wall with two of said chambers for subjecting the wall to a differential pressure varying proportionally with said modified differential in air pressures thereby to increase the effective area of the fuel metering means when the air mass rate of flow exceeds a predetermined value.

11. A device for controlling the supply of fuel to an engine comprising a conduit for supplying air to the engine, a throttle controlling the same, air flow measuring means including a venturi located in said conduit upstream of the throttle for setting up a differential in the air pressures at two spaced points in the conduit proportional to the quantity of air flowing through said conduit, a fuel conduit terminating in a nozzle dischargin in said air conduit, a fuel valve controlling the fiow of fuel through the fuel conduit, a fuel metering orifice in the fuel conduit for creating a differential in the fuel pressures at two spaced points in the fuel. conduit proportional to the fuel flowing through said orifice, means responsive to said air and fuel differential pressures for controlling said valve to regulate the fuel flow and thereby to maintain the differential in fuel pressures proportionally to the differential in air pressures, a by-pass around said orifice, an economizer valve controlling said bypass, a movable wall operatively connected to said economizer valve, and pressure transmitting means interconnecting the opposite sides of said wall with one of said conduits at spaced points upstream from said nozzle at which a differential in pressures is established by and proportional to the flow therein, thereby subjecting the wall to a differential in fluid pressures varying with r' changes in air flow so as to open said economizer valve at a predetermined mass air ficw regardless of engine speed or throttle position.

12. A device for controlling the supply of fuel to an engine comprising an air supply passage, a venturi in said passage for establishing a pair of air pressures having a differential proportional to the air flow to the engine, a fuel supply passage, a fuel metering orifice in the fuel supply passage fixed against orifice area varying movement in response to changes in engine operation, a fuel valve in the fuel passage, means responsive to said differential in air pressures for controlling said valve to supply fuel through said orifice at a rate establishing a pair of fuel pressures on opposite sides of said orifice having a differential in predetermined ratio to said differential in air pressures and proportional to the air flow to the engine, and mixture enrichment mechanism operative under higher than normal power output conditions including an additional fuel orifice in parallel with said metering orifice, an enrichment valve controlling the flow through said additional orifice, a spring yieldingly holding said enrichment valve in closed position, a movable wall connected to said enrichment valve, and pressure communicating means interconnecting each side of said wall with one of said supply passages for subjecting said wall to one of said pairs of pressures for opening said enrichment valve against the force of said spring.

13. A device for controlling the supply of fuel to an engine comprising an air conduit for supplying air to the engine, means in the air conduit for establishing two air pressures having a differential varying proportionally with the rate of air fiow through the conduit, a fuel conduit for supplying fuel to the engine, fuel metering orifice means in the fuel conduit for establishing two fuel pressures having a differential varying proportionally with the fuel flow therethrough, a fuel valve movable to vary the supply of fuel to the fuel metering means, valve actuating means including a plurality of diaphragms subjected to said fuel and air differential pressures in such manner as to be urged in one direction by said air differential pressure balanced by the fuel differential pressure urging the diaphragms in the opposite direction, and means operative only during high engine power output conditions for unbalancing said diaphragms and effecting displacement of said valve to increase the fuel fiow through said valve to enrich the mixture and restore the balance of said diaphragms in the new position of the valve, said last named means including a by-pass around said fuel metering orifice means, and an economizer valve normally closing said by-pass andactuated in a valve opening direction by a movable wall having pressure transmitting connections from each side thereof to one of said conduits for subjecting said wall to two of said pressures the differential of which is proportional to said differential in air pressures.

14. A carburetor comprising a fuel supply passage receiving fuel from a source under pressure and including a fuel metering orifim having a normally fixed area for setting up a differential in fuel pressures on opposite sides of said orifice -in response to flow therethrough, an air flow pasment mechanism for effecting further displacement of said fuel valve to produce an enrichment of the mixture during higher than normal power engine operating conditions, said mixture enrichment mechanism including a by-pass around said fuel orifice, a spring pressed economizer valve normally closing said by-pass, a movable wall connected to the economizer valve, and means intercommunicating each of the sides of said movable wall with one of said passages and subjecting the wall to two of said pressures having a differential varying with ,and proportional to air fiow through the air flow passage regardless of variations in engine speed or throttle position.

15. In a carburetor: air supply passage means including a throttle, Venturi means having a throat of fixed cross-sectional area in all throttle positions, and a scoop; fuel supply passage means including stationary unobstructed metering orifice means of constant metering area in all throttle positions; fuel flow controlling means having air fiow connections to both said throat and scoop, inlet valve means for varying the fuel fiow to said orifice means, and means responsive to changes in the pressures in said throat and scoop for automatically controlling said inlet valve means to maintain a fuel flow through said orifice means for a substantially constant fuel air ratio mixture under both normaland high engine power output conditions; and mixture enrichment mechanism having means for increasing the fuel flow including a movable member movable to control the action of said inlet valve means to enrich the mixture, a valve actuatin diaphragm having one side thereof acted upon by pressure from the throat and the other side thereof by pressure from the scoop whereby said diaphragm is movable proportionally with and in response to changes in said throat and scoop pressures, and spring loading means for preventing movement of said member by said diaphragm to effect such enrichment save underhigh engine power output conditions.

16. A carburetor having fuel suppl passage means including metering orifice. means fixed against orifice area varying movement in re sponse to changes in engine operation, air supply passage means including Venturi means having a throat and a scoop, fuel flow controlling mechanism having air fiow connections to both said throat and scoop, means automatically movable in response to variations in the differential of air pressures in said throat and scoop, and inlet valve means controlled by said last mentioned means for controlling the fuel supplied to said orifice means to maintain a fuel flow for a substantially constant fuel air ratio mixture 18 under both normal and high engine power output conditions, and economizer mechanism havin additional pressure responsive means acted, upon by air pressures from said throat and scoopxand movable in response to variations in said differential of pressures to control said inlet valve.

means to supply additional fuel and enrich the mixture, and means normally biasing said additional pressure responsive means against movement to enrich the mixture and enabling such movement thereof only under high engine power output conditions. 1'7. A carburetor having fuel supply passage means including metering orifice means fixed against orifice area varying movement in response to changes in engine operation, air suppl passage means including Venturi means having a throat and an air scoop, fuel flow controlling means having air flow connections to both said throat and scoop, means automatically responsive to changes in the differential of air pressures in said throat and scoop, and inlet valve means controlled by said last mentioned means for controlling the fuel flow to said orifice'means' to maintain a fuel flow for a substantially constant fuel air ratio mixture under both normal and high engine power output conditions, and mix-.

ture enrichment mechanism including an additional orifice in parallel with said orifice means, a movable element movable to control the fuel flow through said additional orifice and thereby control said inlet valve means to enrich the mixture, actuating means for said element having a pressure responsive member having 'opposite faces respectively subject to air pressures from said throat and scoop, and means normally biasing said element against movement to enrich the mixture and permitting movement of the latter only under higher than normal engine power output conditions.

18. A carburetor having fuel supply passage means including metering orifice means fixed against orifice area varying movement in response to changes in engine operation, air supply passage means upstream from the throttle including means for setting up a differential of pressures proportional to air fiow, valve mechanism including a fuel inlet valve in said fuel supply passage means movable to vary the supply of fuel to said orifice means and normally balanced by opposing pressures of unmetered fuel being delivered to said orifice means, valve actuating means responsive to changes in said differential of pressures in said air passage means and normally balanced by fuel pressures on opposite sides of said orifice means for maintaining a substantiall constant fuel air ratio, economizer means for effecting an increased fuel flow throughsaid fuel supply passage means to enrich the mixture and likewise controlled by changes in said differential of pressures, and pressure responsive means for modifying the action of said differential of pressures on said actuating means and on said economizer means in accordance with variations in the density of the air in said air flow passage means at different altitudes.

19. A carburetor having fuel supply passage means including metering orifice means fixed against orifice area varying movement in response to changes in engine operation, air supply passage means including means for setting up a differential of pressures proportional to air fiow, valve mechanism including a fuel inlet valve in said Euel supply passage means movable to vary the supply of fuel to said orifice means and nor- 19 mally balanced by opposing pressures of unmetered fuel being delivered to said orifice means, valve actuating means responsive to changes in said differential of pressures insaid air passage means and normally balanced by fuel pressures on opposite sides of said orifice means for maintaining a substantially .constant fuel air ratio, economizer means responsive to changes in said differential of pressures in said air passage means for producing an unbalance of said valve actuating means and effecting displacement of said valve to increase the fuel fiow to enrich the mixture, and pressure responsive means'responsive to changes in pressure in said airpassage means due to altitude for modifying the action of said difierential of pressures onusaid actuating means and on said economizer means in accordance with variations in altitude.

20. In a carburetor, air supply passage means including Venturi means having a throat and a scoop, fuel supply passage means including fuel metering orifice means fixed against orifice area Varying movement in response to changes in en- 20 and having a plurality of valve actuating diaphragms coaxial with said valve, means for subjecting the opposite sides of one of said diaphragms to pressures from said throat and scoop, means for subjecting another of said diaphragms to the fuel pressures'on opposite sides of said orifice means, means for subjecting opposite sides of a third diaphragm of said coaxial diaphragms to pressures varying proportionally with and in response to pressure changes in said throat and scoop, and means normally preventing the actuation of said valve by said third diaphragm and enabling actuation of said valve thereby to supply additional 'fuel only under high gine operation and a nozzle projecting into said throat, and fuel fiow controlling mechanism for maintaining a substantially constant fuel air ratio at any constant pressure and temperature of the air entering said air passage means including a fuel inlet valve and valve actuating mechanism including means for maintaining the fuel on opposite sides of said fuel orifice means subjected to pressures from said throat and scoop, and economizer mechanism havin a valve controlling the operation of said fuel flow controlling mechanism to effect the flow of additional fuel through said nozzle to enrich the mixture, and valve actuating means movable proportionally with and in response to variations in the differential of pressures in said throat and scoop and operative only under high engine power output conditions.

21. In a carburetor, air supply passage means including Venturi mechanism having a throat and a scoop, fuel supply passage means including a fuel chamber, fuel metering orifice means fixed against orifice area varying movement in response to changes in engine operation and leading from said chamber, and a nozzle projecting into said throat, fuel fiow controlling mechanism for maintaining a substantially constant fuel air ratio at any constant pressure and temperature of the air entering said air passage means including a fuel inlet valve and valve actuating mechanism including means for maintaining a substantially constant, level in said chamben and also having the fuel pressures on opposite sides of said orifice means varying with the throat and scoop pressures, an economizer valve biased to closed position and operable to control said controlling mechanism to increase the flow through said nozzle to enrich the mixture, and economizer valve actuating means movable proportionally with and in response to variations in the differential of pressures in said throat and scoop to open said economizer valve only under high engine power output conditions.

22. A carburetor having fuel supply passage means including metering orifice means fixed against orifice area varying movement in response to changes in engine operation, air supply passage means including Venturi means having a throat and a scoop, a fuel inlet valve controlling the fiow through said orifice means and normally balanced by opposingpressures of unmetered fuel being delivered to said orifice means engine power output conditions.

23. A charge forming device for an internal combustion .engine comprising a passage for supplying air to the engine, a throttle controlling the same, air differential pressure creating means in said passage anterior to the throttle for setting up a differential of air pressures varying proportionally with the quantity of air flowing through said passage throughout the entire range of engine operation, a fuel conduit for introducing fuel into the engine, valve means controlling the flow of fuel through said conduit, a fuel metering orifice in said fuel conduit for creating a fuel differential pressure therein, means responsive to changes in said differential of air pressures for effecting displacement of said valve means to deliver through said orifice sufficient fuel to produce a predetermined fuel air ratio during normal engine power output conditions and during high engine power output conditions, and mixture enrichment mechanism biased against operation save under higher than normal engine power output conditions and including additional fluid pressure responsive means, subject to pressures producing a differential of pressures varying proportionally with and in response to changes in said differential of air pressures throughout high engine power output conditions, for efi'ecting further displacement of said valve means to superimpose on said predetermined fuel air ratio an increased fuel flow producing'an enrichment of the mixture, and having said additional pressure responsive means movable while said first mentioned pressure responsive means continues to effect its own displacement of said valve means, said mixture enrichment mechanism also having open passages connecting the opposite sides of said additional pressure responsive means with opposite sides of said orifice, and said mechanism also including a by-pass around said orifice, and a valve actuated by said additional pressure responsive means and varying the opening of said by-pass proportionally with and in response to the drop across \said air differential pressure creating means.

GUY E. BEARDSLEY, Ja.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS (Other references on following page) Number Number FOREIGN PATENTS Country Date Great Britain Sept. 18, 1912 Great Britain Sept. 26, 1918 Great Britain May 1, 1919 Great Britain Jan. 20, 1921 Great Britain Apr. 15, 1937 Great Britain Sept. 6, 1937 Great Britain July 25, 1940 France Nov. 10, 1922 France May 4, 1922 France Mar. 24, 1938 Austria Sept. 10, 1925 Italy Jan. 20, 1939 Certificate of Correction Patent No. 2,447,264.

GUY E. BEARDSLEY, JR.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 6, line 26, for orifices 36 hereto read orifice 86 heretofore; column 9, line 69, for downwrd read downward; column 11, line 49, for mechanism read mechanisms; line 69, for 0t read to; column 15, line 45, claim 10, for valves read valve; column 18, line 61, claim 18, and column 19, line 13, claim 19, for pressure responsive read anero'id; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 14th day of December, A. D. 1948.

THOMAS F. MURPHY,

Assistant Oommz'ssz'oner of Patents.

August 17, 1948.