US2457765A - Carburetor - Google Patents

Description

Dec. 28, 1948.

A. 'H. WINKLER 2,457,765

CARBURETOR Filed July a1, 1943 igr 53$ INVENTOR ALBERT h. \A/INKLER Patented Dec. 28, 1948 2,457,785 CABBURETOB Albert II. Winkicr.

Bendix A a corporation of South Bend, Incl. or to vlation Corporation, South Bend, Ind.,

Delaware Application July 31, 1943, Serial No. 496.898 Claims. (Cl. 281-69) This invention relates to fuel feeding systems for internal combustion engines and more particularly to devices or systems in which liquid fuel is supplied thereto under superatmospheric pressure and is metered while being maintained under pressure. Certain subject matter of this application has been divided therefrom and is now embodied in applicant's copending applications Serial No. 600,469 filed June 20, 1945, and Ser. No. 603,783, filed July 9, 1945.

One of the principal objects of the invention is to provide a simplified device of this character which may be built at reasonable cost and which is capable of accurately regulating the fuel supply to maintain a proper fuel to air ratio through wide ranges of engine load, speed, and variations in altitude such as are experienced with an alrcraft engine.

Another object of the invention is to eliminate boiling of the fuel under high temperature or altitude conditions to thereby insure accurate metering. This is accomplished by maintaining a fuel under positive pressure until it is discharged into the air supply to form a combustible mixture for the engine.

In fuel feeding systems of this character it is known to use a metered fuel control valve of the poppet or unbalanced type. Suction in the induction passage will therefore afl'ect its position. a result that may have particularly disadvantageous results when the engine is operating in its idling range (the induction passage suction then being relatively high) and the quantity of fuel mixture supplied is relatively small. Under such conditions a very slight variation in the position of the fuel valve will cause a relatively great change in the ratio of fuel to air in the mixture.

It is therefore another object of the invention to provide a device of this character wherein fuel metering is substantially unaffected by variations in suction in the induction passage and the mixture is maintained at a substantially constant richness although manifold pressures may vary through rather a wide range. This is effected by providing a fuel nozzle including an emulsion chamber wherein substantially atmospheric pressure or the pressure at the entrance of the carburetor; which may be modified by impact or suction tubes. is maintained so that metering of fuel delivered thereto is substantially unafl'ected by variations in the suction in the induction passage. the emulsion being delivered to the induction passage through a passage of limited fiow capacity, which particularly during idling is subjected to conditions of critical now.

groove thereof. Still another object of the invention is to pro- Figure 1 is a diagrammatic sectional view a carburetor embodying the invention;

Figure 2 is an enlarged partial view in section of the discharge nozzle shown in Figure '1; and

Figure 3 is an enlarged partial view in section or the idle and economizer needle valve.

Throughout the drawings, similar reference characters represent similar parts although where such parts are modified in structure and operation they are given a further din'ering reference character.

With reference to Figure i, there is shown a main body member I which contains an induction passage l2 therethrough having an air inlet 14 and an outlet I 6, the air inlet being provided with an outer surface l8 to which an air scoop (not shown) opening in the direction of travel may be secured and the outlet being provided shown) for securing the body member I 0 to the manifold of an internal combustion engine or to the inlet of a supercharger if one is used between the carburetor and the maniinlet and outlet sections is positioned in the induction passage adjacent the inlet It and is formed with an annular chamber 22 which communicates with the interior of the venturi through annular slot 24 to be thereby subjected to Venturi depression. An annular chamber 26 is in free communication with the air entering the venturi through an annular opening 28. the opening 28 be used. The center portions being preferably subjected to the impact pressure of the air supplied to the venturi. A throttle I is pivotally mounted in the induction passage posterior to the venturi and is adapted to be manually actuated to control the air flow to the engine.

The fuel flow to the engine is regulated or controlled by an unmetered fuel pressure control unit or regulator, indicated generally at 32, which regulates or determines the fuel pressure on the upstream side of a fuel metering unit, indicated gnerally at 04, and by a discharge nomle assembly indicated generally at 38 which regulates or determines the pressure on the downstream side of the metering unit 34. If desired, a metering orifice of fixed size may be used instead of the meterlngunit 3|.

The interior of the regulator unit 32 is divided into three chambers l0, l2 and M by diaphragms l6 and 48. As shown the diaphragms 40 and 40 have an area ratio of /2 although, as will be apparent hereinafter any desired area. ratio may of the diaphragms are supported by thin plates 50 between which the diaphragms are clamped by centrally disposed cylindrically recessed rivets 52 and I4. Washers 58 are preferably provided under the deformed end of the rivets so that the thin plates will not tear loose from the riveted over portion of the rivets. The ends of a pin or rod 50, freely received in the recesses of the rivets, are preferably provided with rounded ends to form angularly adjustable oneway connections with the diaphragms whereby slight misalignment of the diaphragms may be accommodated without binding. This construction also greatly facilitates assembly and disassembly of the control unit 32.

Chamber 40 is provided with a fuel inlet port controlled by a valve 80 and receives fuel from a source of fuel under pressure, such asa fuel pump, through a pipe 02. The valve 0 has a pinlike extension projecting into the chamber 00 in position to be engaged by the headoi rivet 02 whereby movement of the diaphragms to the right opens the valve. A spring Bl urges the valve to its closed position. A spring 60 is mounted at one end in the chamber H and has its free end received in a spring retainer portion of a lever 68 pivotally mounted at one end and having a crimped center portion normally engaging the head of rivet M and urging the diaphragms to the right in a direction to open the valve 80. The spring 00 may be rendered inoperative. when the engine is to be stopped. by a plunger 10 which upon downward movement thereof engages the free end of lever 08 and moves the lever to the left against the force of spring 06. The lever 68 will thus move out of engagement with the rivet 50 whereby the spring 00 may close the valve 00 and cut off the fuel supply to the engine. In order to eliminate vapor, a pipe 12 having a restricted communication with the top of chamber 40 is preferably provided which leak back to the fuel supply tank.

The chamber 42 of the regulator unit 32 is connected to the Venturl annulus 22 by means of a pipe I0 and passage 16 and is therefore subjected to a pressure primarily derived from the throat of the venturi 20. A restriction 10 may be provided in passage 14 if desired. The chamber 02 is also connected to the air scoop or Venturi entrance by means of a passage 00 controlled by a manual mixture control valve 02, a passage 80, and the annular chamber 26. The chamber M of the regulator unit 32 is connected to the annular Venturi entrance chamber 20 by a branch passage 05 of the passage 04 and is therefore subiected to a pressure primarily derived from the Venturi entrance. A restriction 88 may. if desired, be provided in the branch 05. The chamber 44 is also connected to the Venturi annulus 22 through es I0. 92 and II, the communication betweenpassages gland 92 being controlled by a valve of an automatic mixture control unit 86. Unmetered fuel entering the chamber 40 of the regulator from the fuel inlet 62 is transmitted through a pipe 08 to a chamber Hill of the fuel metering unit 24, and thence through the meteringunit to a pipe I02 leading to a chamber III! of the discharge nozzle 36.

The fuel metering unit 30, which determines the effective area of the fuel metering restriction under various conditions of operation, may be'formed as a part of the main body I0. or of the regulator 02,,or may be} a separable unit secured to the body or regulator as desired. A diaphragm I06 separates the chamber I00 from a chamber I0! and is secured to a metering valve IIII (best shown in Figure 3) slidable in a plug H2 and having a double stepped end Ill, I I6 cooperating with a metering orifice IIIl formed in the plug II2. If desired, a second orifice I20 may be provided to limit the flow of fuel when the valve I Ill is entirely withdrawn from the orifice IIB. As shown the orifice I20 is located in the plug I l2; however, it may be placed at any desired point in either of the passages I02 or 98. The chamber I0! is connected to the Venturl. annulus 22 by means of a pipe I22 and the passages 14 and I6.

A cup member I20 forms a stop, limiting movement of diaphragm I06 to the left, and may be adiustably mounted as by threading. A piston I20'is slidably mounted in the cup member I24 and projects therethrough into abutting relation with the diaphragm [00 of the valve ,I I0 to thereby limit'the permissible'movement to the left of diaphragm I00 under the influence of the fuel pressure in chamber I00. The piston I28 is provided with a reduced diameter extension I28 adapted to be engaged at idle by a cross bar I30 adiustably secured to a slidably mounted rod I32 which is urged to the left by a spring I34 and is moved to the right at idle by a throttle lever finger I38 engaging a flange I38 on the rod I32. A stop I00 limits movement of rod I32 to the left at such times as the throttle is open beyond its idling or near idling positions. A washer I42. slidable within the cup member IN, is urged to the right against the bottom of the cup member by a preloaded sprlng I". The washer is adapted to engage the shoulder of piston I25 to limit the movement to the left of said piston. diaphragm I06. and valve H0, whereby as the throttle is opened beyond the near idling position the fuel pressure in chamber I00 moves the valve "0 to .the left only sumciently f or to withdraw the step I I from the orifice III. During high power operation, however. the high unmetered fuel pressure in chamber Ifland the low Venturi pressure in chamber I00 create a sufllcient pressure diflerem tial across the diaphragm I06 so that the spring I is further compressed and step I It at the end of valve III is completely withdrawn from the orifice HI.

Thus during idling, with the parts as shown in Figures 1 and 3, the step I cooperates with the orifice Ill to limit the area for fuel flow. As the throttle is opened through the near idling range the valve 0 moves to the left until the piston I20 engages the washer I12, at which time 6 the step I I6 cooperates with the orifice H6 toiimit the area for fuel flow during normal cruising operation. At high power output the step "6 is completely withdrawn from the orifice III, at which time said orifice H6, or the orifice I26, or both, determine the eflective fuel metering area.

Fuel passing through the metering unit 64 is transmitted through a pipe I62 to a chamber I64, in the discharge nozzle assembly 66, which is separated from a chamber I66 by a preformed annularly grooved diaphragm I62 connected to a fuel outlet valve I64 and urged to the right in a direction to close the valve by a spring I66 arranged to be variably loaded by screw I66, said chamber I66 being connected to the Venturi annulus 22 by the passage I6. The stem of valve I64 is of triangular cross section or otherwise relieved to permit fuel flow therepast and is slidable within the nozzle bar I66. In this arrangement the valve I64 is not fixed to the diaphragm I62 but is maintained in abutting relation therewith by means of a light spring I62 which constantly urges the valve I64 to the left. This arrangement eleminates any tendency for the valve to bind in its valve guide and seat member I64 as a result of misalignment between the diaphragm and the guide member.

The discharge nozzle, as best shown in Figure 2, comprises a member I66 mounted in the wall of the body I6 and extending transversely of the induction passage I2. The member I66 is provided with a reduced diameter end portion I66 having a groove I16 therein. The portion I66 projects into an enlarged portion I'I2 of a tubular extension I14 f the valve guide and seat member I64, the outer surface of the end I66 being substantially concentric with but spaced from the inner surface of the enlarged portion I12 to thereby form an annular fuel passageway I16 0! limited flow capacity, an emulsion chamber formed by the groove I16, and a second annular passageway I16 of limited flow capacity which leads to an annular space I66 from which fuel emulsion is discharged into the induction passage The tip I62 of the end I66 is preferably pointed or otherwise formed so that fuel received past the valve I64, through the passage I64, will be readily directed outwardly to the annular passageway I16. Ports I66 connect the groove I16 with a bore I66 in the member I66 which receives air through passage 266 from the annular venturi entrance 26.

An acceleration pump indicated at 262, which may be provided if desired, includes a suction chamber 264 connected through pipe 266 with the induction passage I2 posterior to the throttle. A diaphragm 266 urged to the left by a spring 2| 6 separates the suction chamber 264 from a fuel chamber 2l2 connected through a pipe 2 with the fuel the diaphragm 266 is moved to the fuel robbed from the chamber I64 is drawn into the chamber 2 I 2. Upon a loss in engine sucacceleration, the spring 2I6 forces the diaphragm to the left and pumps fuel from chamber 2l2 to the nozzle chamber I64 thereby temporarily richening the mixture. An adjustable stop 2I6 is provided whereby the stroke of the diaphragm 266 may be varied.

The automatic mixture control unit 66. which is responsive to variations in altitude, includes a. plug 226 which carries a seat portion 222 and is screwed into any desired fixed member, which may be the body I6. The stem of valve 64 is slidright and the an adjustment.

ably received within "the piugfll and is secured an end closure member 224 of a corrugated bellows 226, the other end or which is secured to a base 226 to which a cap 266 is also secured. The bellows and cap iorm walls of a sealed chamber 262 which may be evacuated to any desired degree. By controlling the degree of the pressure and temperature responsiveness of the bellows may be correlated as desired. If desired a quantity or fluid may be used in chember 262 to aid in obtaining the desired temperature responsiveness. The base 226 is threadedly and is separated therefrom by shims 264, the number of thickness of which may be readily varied to adjust the zero setting of the valve 64 relative to the seat portion 222.

oppositely disposed ports terior of the bellows 226 with annular chamber 236 whereby the pipes 66 and 62 may communicate with the interior of the bellows, thereby making the control unit 66 responsive to changes in the temperature and pressure of the air entering the venturi. The unit 66 may, it desired, be placed closely adjacent to or in the air inlet so as to be in direct contact with the entering air. Also if desired the interior of the bellows 226 may be connected directly to the inlet.

The calibrated passage 66 interconnects the chambers 42 and 44 and is controlled by the spring closed manual mixture control valve 62 adapted to be opened any desired amount from the pilots compartment by a cable actuated member 266. The stem of valve 62 is provided with a collar 262 which engages a pivoted lever 264 to force the plunger 16 downwardly when the mixture control valve is moved beyond its wide open or lean position to its idle cut-ofl position.

Operation of the device disclosed in Figure 266 connect the in- The operation 1 is as follows:

Assuming the carburetor has not been filled with fuel and the idle cut-oil plunger 16 is in its upward position as shown, the sprin 66 will urge the diaphragms to the right and open the valve 66. Fuel under pressure supplied to pipe 62 enters and fills chamber 46 and flows through the unit 64 and pipe I62 to the chamber I64. As the pressure in chamber 46 increases it acts against the diaphragm 46 and tends to compress spring 66 whereby the valve 66 tends to close. Fuel under pressure supplied to chamber I64 acts on diaphragm I62 and tends to open valve I64. The screw I66 is normally adjusted to compress spring I66 to such a point that a slightly lower pressure is required in chamber I64 to open the valve I64 than is required in chamber 46 for suiilciently compressing the spring 66 to permit the valve 66 to close. Once the carburetor has been fully filled with fuel, fuel will therefore slowly spill from the discharge groove I86 unless the lever 266 is actuated and the plunger I6 forced downwardly to compress spring 66 and so allow valve 66 to close. Although the screw I66 has been described as being adjusted to permit valve I64 to open at a pressure somewhat less than the closing pressure for valve 66, it will be apparent that by screwing the adjustment screw I68 in or out of the pressure in chamber I64 required to open valve I64 may be made greater than, equal to or less than the pressure required in chamber 46 to permit the valve 66 to close. It will also be apparent that the actual value or degree of the fuel pressures will be determined by the strength evacuation,

of the springs 08 and its, the pressure required being greater as the strength of the spring is increased.

It has generally been found desirable to adjust the discharge nozzle spring I" suiiiciently weaker, in proportion to the area of the diaphragm ill, than the spring 86, in proportion to the area of diaphragm 46, so that at idle an excessively rich mixture is obtained, and then to decrease the richness of the idling mixture by decreasing the eflective area of the metering orifice H8 during idling operation. It is for this reason that the valve ill! and the rod I32 function to reduce the metering orifice area at idle. By controlling the rate at which the valve illi is permitted to move to the left as the throttle is opened'from its idle position, any desired near idling mixture richness can be obtained.

During operations, assuming the area ratio of the diaphragm l8 and 48 is equal to two, the regulator unit 32 functions to mtaintain a differential fuel pressure across the metering unit M which is equal to twice the venturi to entrance air differential pressure. For example. a given decrease in the pressure in the Venturi chamber 22 is transmitted to the chamber 42, where it results in an equal increment increase in the unmetered fuel pressure in chamber 40, and is transmitted to chamber Hi4, where it results in an equal increment decrease in the metered fuel pressure. Consequently the fuel metering differential pressure is increased in amount double the increase in the air differential. Similarly a given increase in the entering air pressure in the chamber 26 is transmitted to chamber 44 and since it is applied to the diaphragm 18 having twice the area of diaphragm 46, the unmetered fuel pressure in chamber 40 is increased an increment double the increase in entering air pressure.

Although the diaphragms l8 and 46 are shown as having a two-to-one area relationship, they may be of any other desired area ratio, in which case the fuel metering differential pressure will be maintained at some multiple, other than two, of the air differential pressure. For example, if the area of diaphragm 4B is three times the area of diaphragm 46, the fuel differential will be maintained equal to three times the air metering differential. Or, if diaphragms 46 and 48 are of equal size, the fuel metering diilerential pressure is maintained substantially equal to the air differential pressure. In any event, the fuel and air diiferential pressures are maintained in constant proportion and therefore constant fuel to air proportionlng is obtained.

In order to minimize the disturbance of the ratio of fuel to air by induction passage suction on the valve In, which is of the unbalanced type, a critical flow nozzle, one embodiment of which is shown in Figures 1 and 2, is provided and constitutes an important element of the present device. In this nozzle the emulsion chamber I10 is freely supplied with air through the ports I88 at substantially atmospheric or entering air pressure and said emulsion chamber is connected with the induction passage by a restricted calibrated passage liii. Therefore, as the passage I18 is one of limited flow and the chamber I" is freely supplied with air at atmospheric or entering air pressure, the pressure in chamber I" is maintained substantially constant at said atmospheric or entering air pressure regardless of variations in induction passage suction at or beyond the point of critical flow of passage I'll. with this arrangement the fuel pressure in passage Ill.

Ill

and consequently the fuel metering. is substantially unafl'ected by variations in the suction at the annulus I80. In addition, the restricted annular passageway ill .iunctions as a critical flow nozzle, relative to the air bled to said nozzle, at low manifold pressures corresponding to idling, so that fluctuations in manifold pressure at or above said critical flow point, for a given fuel flow as determined by the regulator, are ineffective to vary the quantity of air being drawn through the ports i". By this means a mixture of constant richness is provided even though the idling manifold pressure varies through rather wide limits.

It is generally desirable to provide the pilot with a manual mixture control so that he can vary the richness of the mixture between predetermined limits. For this purpose the calibrated passage 80, controlled by the tapered valve 82 is provided, which with the valve closed corresponds to a rich setting. As the valve 82 is opened, air is bled from the air scoop chamber 14 into the Venturi chamber 42 whereby the difierential pressure between these chambers is reduced an amount depending upon the extent the valve ii! is opened. This in turn reduces the unmetered fuel pressure in chamber to required to maintain the diaphragm assembly in an equilibrium position, thus reducing the fuel metering differential and consequently reducing the richness of the mixture for a given air flow. With the valve 8: completely withdrawn the carburetor is in its full lean position, the effective area of passage Bil, as limited by the seat of valve 82, determining the maximum permissible bleeding action.

The automatic mixture control unit 96, or altitude control unit, as it is sometimes referred to, is provided to maintain a constant mixture richness with variations in altitude, and functions on substantially the same air bleed principle as the manual mixture control. Upon a decreas in the density of the air entering the venturi, as by increase in altitude, the differential between the entering air and the Venturi pressures will increase for a constant weight of air flow per unit time and will tend to increase the fuel flow and enrich the mixture. As the density decreases, however, the bellows 216 collapses. because of the decreased pressure within the bellows, and moves valve 84 upwardly to increase the area of communication between the pipes 9t and 92. Air is thus bled into the Venturi chamber 42 to thereby reduce the diflerential pressure which would otherwise exist between the chambers l2 and M, whereby the unmetered fuel pressure in chamber All is correspondingly decreased. By proper- 1v contouring the valve 94, the differential in the air pressures in chambers 42 and N are so controlled that the fuel supplied to the engine remains constant for a given weight or air flow p r unit time even though the entering air density changes. Automatic altitude compensation is thus obtained.

with the orifice 88 positioned as shown and properly proportioned relative to the orifice II. the manual mixture control will function primarily to vary the pressure in chamber 42 to thereby vary the diflerential between the pressures in chambers 42 and I; whereas, the automatic mixture control so will function primarily to vary the pressure in chamber to thereby vary said differentlal. If dmired, however, restriction 8 ma be eliminated and restriction I! placed in the passage ll to the left of passage 2, in which case both controls would tend to have their major effect upon pressure in chamber 42. Other arrangements of the restriction may be used if desired.

When the engine is to be stopped it is desirable to cut of! all fuel flow thereto so that it will not continue to run, as a result of pre-ignition. after the ignition is turned off. To accomplish this end, the valve 82 is moved upwardly beyond its full leanposition to an idle cut-oil position at which the plunger 'Ifl'is forced'downwardiy by the lever254 whereby the spring 58 is compressed and the light spring 84 is able to fully close valve 60.

It will also be understood that many charges might be made in the form and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages and it is not intended that the scope of the invention shall be limited to the form shown and described nor otherwise than by the terms of the appended claims.

I claim:

1. In a charge forming device having a throttle controlled induction passage: a discharge nozzle comprising a pair of members projecting into the induction passage from opposite sides thereof and having their ends in spaced telescopic relation forming an annular space between the telescoped portions; a passageway in the outer of the two telescoping members in communication with the annular space; a groove in the outer surface of the inner member enlarging the intermediate portion of the annular space to form an emulsion chamber; an air supply duct in the inner of the two telescoping members communicating with said groove; a shoulder on the inner member in spaced relation to the adjacent free end of-the outer member thereby providing an annular discharge groove in communication with said annular space; and means for supplying fuel to the passageway of the outer member.

2. In a charge forming device having a throttle controlled induction passage: a discharge nozzle comprising a pair of members projecting into the induction passage from opposite sides thereof and having end portions in spaced telescopic relation forming an annular space therebetween: a shoulder on the inner member in spaced relation to the adiacent free end of the outer member thereby providing an annular discharge groove in communication with the annular space; a passageway in the outer of the two telescoping members in communication with the annular space; a groove in the outer surface of the inner member enlarging an intermediate portion of the annular space to form an emulsion chamber; a passageway in the inner of the two telescoping members communicating with said groove; means for supplying fuel to one of the passageways; and meansfor freely supplying air to the other passageway, the annular space between being so calibrated that suction transmitted from the induction passage to the emulsion chamber will reach the maximum value at a predetermined induction passage suction and will not vary appreciably from said maximum value upon a rise in induction passage suction above said predetermined suction.

3. In a discharge nozzle for a fuel supply system: a pair of oppositely extending members having their ends in spaced telescopic relation forming a calibrated annular space therebetween thereby providing a fuel emulsion discharge passage of limited flow capacity; a fuel passageway in the outer of the two telescoping members in communication with the annular space: a shoulder on the inner member in spaced relation to the adJacent free end of the outer member thereby forming an emulsion discharge groove in communication with the annular space: a groove in the outer surface of the inner member enlargin an intermediate portion of the annular space to form an emulsion chamber; an air passageway in the inner of the two telescoping members communicating with said groove; means for supplying fuel to one of the passageways; means for supplying air to the other passage, said annular space being adapted to limit fluid flow therethrough to a critical maximum: and a conical tip on the free end of the inner member which tapers to a point facing the fuel flow.

4. In a charge forming device: a throttle-controlled air-intake passage having a venturi therein anterior the throttle, a fuel conduit leading from a source of fuel under pressure and termiacting in a fuel-discharge nozzle located in said passage. a fuel-metering restriction in said conduit, means for regulating the pressure of fuel upstream of said restriction, means for regulating the pressure of fuel downstream of said restriction independently of upstream pressure thereof including a valve controlling flow of fuel to said nozzle and spring-pressed toward closed position and subjected in a valve-opening direction to the pressure of fuel downstream of said restriction and to venturi suction; said discharge nozzle having an emulsion chamber receiving liquid fuel from the fuel conduit at pressures determined by said valve, a discharge passage communicating the emulsion chamber with the air intake passage posterior the throttle, and means for supplying air to said emulsion chamber, said discharge passage being calibrated in a manner such as to limit the suction effect on the emulsion chamber to a critical maximum so that under certain conditions of operation, for example, at partly or fully closed throttle when Venturi suction is at a low value and posterior throttle suction is high. the disturbing effect of intake passage suction on the said valve and hence on the fuel-air ratio will be minimized.

5. In a charge forming device: a throttle-controlled air-intake passage having a venturi therein anterior the throttle, a fuel conduit leading from a source of fuel under pressure and terminating in a fuel-discharge nozzle located in said passage, a fuel-metering restriction in said conduit. means for regulating the pressure of fuel upstream of said restriction including a fuel valve to which fuel is supplied at substantially constant pressure and pressure-sensitive means controlling said valve and arranged to be responsive to variations in the flow of air through said air-intake passage and unmetered fuel pressure upstream of said restriction, means for regulating the pressure of fuel downstream of said restriction independently of the pressure upstream thereof including a discharge-nozzle valve controlling flow of fuel to said nozzle and a pressure-responsive element connected to said latter valve and subjected to the perssure of fuel downstream of said restriction and Venturi suction: said discharge nozzle having an emulsion chamber receiving liquid fuel from the fuel conduit at pressures determined by said dischargenozzle valve, an emulsion-discharge passage communicating the emulsion chamber with the air-intake passage posterior the throttle, and means for freely supplying air to the emulsion chamber, said emulsion discharge passage being 11 calibrated in a, manner such as to limit the suction eil'ect on the emulsion chamber to a critical maximum so that under certain conditions 0! operation, ior example, at partly or fully closed throttle when venturi suction is at a low value and posterior throttle suction is hilh. the disturbing eil'ect of intake passage auction on the said valve and hence on the fuel-air ratio will be minimized.

AIBERT H. WINKLER.

REFERENCES CITED Name Date Schulz Sept. 19, 192

Number Number ame Date Thomas Dec. 14, 1926 Gross Dec. 12, 1988 Wynne et al. Oct. 80, 1984 Mennesson June 21, 1988 Dawes Aug. 28, 1988 Browne July 11, 1989 Olson May 7, 1940 McCain Apr. 15, 1941 Ouip Mar. 81, 1942 Mock et al Feb. 16, 1948 Weiche -5 Sept. 28, 1948 FOREIGN PATENTS Country Date Great Britain Mar. 18, 1929 Austria Aug. 15, 1920

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