US1858387A - Carburetor - Google Patents

Description

May 17, 1932. v c. c. BRADBURY E11-AL 85838-7 CARBURETOR Filed Oct. 10, 1928 3 Sheets-Sheet l May 17,1932. c. c. BRADBURY ET AL CARBURETOR- Filed Oct. 10, 1928 3 Sheets-Shet 2 May 17, 1932.

c. c. BRADBURY ET AL CARBURETOR Filed oct. 1o. 1928 5 sheets-sheet s Patented May 17, 1932 UNITED STATES YPATENT OFFICE CLIFFORD C. BRADBURY, ,0F GLENCOE, AN D ROBERT IE'. BRACKE, OF CHICAGO, ILLINOIS,

` .ASSIGNORS TO CURTIS B. CAMP, TRUSTEE, 0E GLENCOE, ILLINOIS CARBUEETOR Our invention relates to improvement in carburetors and more particularly to carburetors of the fuellkift type.

In carburetors of this type fuel is lifted to the fuel nozzle by induction chamber def pression, thus maintaining the fuel chamber and fuel passages under constant depression `during operation. This depression in the fuel chamber and fuel passages causes the liquid fuel to give off gas as if boiling and if this gas is allowed to reach the fuel nozzle in slugs or large bubbles it momentarily shuts off the fuel supply to the induction chamber causing erratic carburetor action. This condition prevails particularly in warm weather and has been `a serious draw-back to the eicient operation of fuel lift carburetors because of the necessity of maintaining a certain yvolume of fuel under the influence of this depression. When air is bled into the fuel in uniform quantities near the fuel nozzle so that there is no opportunity for the air to collect in large bubbles it is not particularly harmful. Thus, slight leaks around economizer valve stems and the like may do no harm if the air thus bled in can pass to the nozzle without collecting in slugs or bubbles.

An yobject of our invention is to provide a carburetor of thevacuum feed type which will operate to deliver fuel to the induction chamber at all times without interruption by the presence of gas or air from the fuel chamber or passages leading to the fuel nozzle.

Another object is to provide a carburetor wherein gas and air are automatically with-` drawn from the fuel chamber while the car.- buretor is in operation to continuously maintain the chamber free of gaseous pockets from which the gas can be drawn to the nozzle.

A further object is to provide a carburetor wherein a higher `degree of suction is em-y ployed for removing the gas and air from the fuel chamber or passages than that to.

which the fuel is subjected for conduction of y the fuel from the chamber to the fuel nozzle.

4Application filed October 10, 1928. Serial No. 311,646.

the air Withdrawal passage by suction'from n A wherein the passage through which gas and air are withdrawn from the fuel system offers relatively low resistance to the passage of gas but Very high resistance to the passage of fuel, therefore permitting but a negligible quantity of fuel to be withdrawn when all of the gas and air have been eliminated as described.

A further object is to provide a carburetor wherein air which may-bleed past the econolnizer valve stem by reason of the depression in the economizer valve chamber is removed before it reaches the valve chamber, thereby eliminating the entrance of air into the fuel system around the fuel economizer valve stem.

Another object is to provide a carburetor wherein back suction created in the fuel line to the carburetor during acceleration due to inertia of fuel therein is not communicated to the fuel nozzle to temporarily shut off fuel flow thereto.

Other objects and advantages will herein- 4 after appear.

Our invention will be explained as embodied in a vacuum feed carburetor of the fuel lift type as illustrated in the accompany- Fig. 3 is a fragmentary plan View illustrating the air withdrawal venturi in section,

Fig. 4 is a sectional view along the line 4-4 of Fig. 3.

Fig. 5 is a sectional view along the line 5--5 of Fig. 2.

Fig. 6 is a schematic sectional view for illustrating the relative position between the fuel delivery venturi and the air withdrawal mechanism.

Fig. 7 is a sectional view of the motor vehicle equipped with our improvedcarburetor, an

Fig. 8 is a fragmentary view partly in section of a silencer foi` the fuel nozzle.

. stricted Vpassage E interconnecting the throat of venturi D with the upper part of the fuel chamber B, for Withdrawing'gas or air from the chamber at a higher suction than that at which fuel is withdrawn by fuel Venturi tube A.

u The invention also contemplates a passage F having one end communicating at Gr with the induction passage above the throttle valve 13 of the carburetor and the other end with the space between the economizer valve stem H and its support, ,thereby subjecting the air about the stem to a normally higher depression tlian that to which the fuel in the system is subjected for the purpose of preventing the entrance of air to the fuel system from around the valve stem.

The fuel venturi A4 comprises a primary air inlet to the induction chamber C. The secondary air inlet consists of a relatively larger passage having a. choke valve 11 about which the major part of air admitted to the carburetor passes. A spring operated air valve 12 serves to control the passage of secondary air to the induction chamber and to maintain a sufficient and properly proportioned depression in the chamber for lifting fuel and properly feeding it to the induction chamberV under all conditions of operation. A throttle valve 13 in the delivery port 14 of the carburetor serves to control the passage of fuel mixture to the manifold 15 The fuel chamber B communicates through a diaphragm operated fuel valve with a vfuel conducting tube 21, the other end 22 of which is disposed within the main `fuel supply tank 23 usually located at the rear of the vehicle. ing operation a normally uninterrupted fuel passage between the main supply tank 23 and the-fuel venturi or nozzle A.

The fuel valve diaphragm 24 is operated by atmospheric pressure, upon depression vin the fuel chamber, to-open the fuel valve 20 variable amounts thus permitting fuel to be drawn past the valve in such quantities'as to maintain a substantially constant depression in the fuel chamber below the diaphragm. From this chamber the fuel is drawn directly to the fuel venturi A.- The fuel Venturi tube or nozzle A has its delivery orifice 25 projecting within the chamber C and its inlet 26 communicating with the atmosphere.

There is thus established durend of which communicates with the lower portion of chamber B. The passage of air through the venturi by induction chamber depression creates a depression at the throat which is greater than the depression at the outlet or delivery orifice 25.. This is a distinguisliing characteristic of the Venturitube. As a result of this arrangement the fuel chamber is at all times during normal operation of the carburetor subjected to sufficient depression to assure the lifting and conduct-y ing of the ,fuel from the main supply tank 23 to the Venturi tube without the necessity of an unduly high suction in the induction chamber of the carburetor.

The greater the depression in the induction chamber the less theultimate engine power, which gives rise to the desire for slight induction chamber depression.

Air Venturi tube Dis substantially identical to the Venturi tube or nozzle A but is much smaller in size. Its throat 3() is interconnected by radial passages 31 with the restricted passage E through which gas accumulating in the fuel chamber may pass as it is drawn therefrom to the throat of the air venturi. The suction multiplying property of venturi D is more pronounced than 1s that of the fuel venturi or nozzle A, due principally to the fact that gas or air admitted to the throat 30 of the venturi does not appreciably exert a chocking etl'ect upon the venturi action. In the fuel venturi A there is such a choking effecty due to fuel vaporization and hence the depression in passage E will always'be greater than that 1n passage 28.

The passage E is restricted by a pin 35 extending longitudinally therethrough and -held in place, see Fig. 4, centrally in passage E by a screw plug 36 to which they rod is secured. There is a tolerance of two to five thousandths of an inch between the rod and the passage so as to purposely offer relatively high resistance of the movement of fuel therethrough bu-t to readily permit the pasvzle A.

The fuel valve 20 does not rest directly against the diaphragm 24 but against a cap Y 40, which cap in turn engages at 42 with the diaphragm.

An adjustable compression spring 49 encompassing the valve 20 bears against the cap 40 for the purpose of controlling the shutting of the valve by the diaphragm 2 4 at the desired fuel chamber depression. Thls spring also acts as a baille tobreak up gas' bubbles which may be admitted to the chamber through valve as incoming fuel'must pass between the adjacent turns of the spring.

It will be noted that inlet orifice 43 of passage E at the fuel chamber is spaced a considerable distance below the plane of dia-- phragm 24 so that an air cushion is formed Within the fuel chamber immediately beneath the diaphragm.

The lower region 32 of the fuel chamber below the fuel valve 2O into whichfuel from fuel line 21 is first received is enlarged and a tubular inlet 33 for valve 20 extends downwardly toward the bottom of the region 32. A metal tubular baille 34 surrounds the inlet 33 and is closed at its lower end by a strainer screen 37. Air admitted through the fuel line 21 may pass over the top of the baffle 34 while fuel passes through the bottom recesses indicated in dotted lines and up through the strainer screen 37, where it is drawn through inlet 33 through valve 2() and into the upper portion of the fuel chamber. The purpose of the downwardly` extending inlet 33 is to create during normal operation of the carburetor au air cushion which may expand upon the creation of back suction in fuel line 21 as during acceleration and thereby assist in preventing communication of the back suction in the fuel line to the fuel nozzle.

The air cushion formed beneath diaphragm 24 further assists in permitting free flow of fuel to the nozzle during the presence of back suction in the fuel line by expanding as fuel is drawn through passage- 28 from the .fuel chamber to the nozzle. In order that the nozzle may not be deprived of fuel during the accelerating period the back portion of the fuel chamber communicating with passage 28 should be of suiiicient sizeA to contain fuel enough to' supply the nozzle during the entire period of acceleration or so much of that period as is accompanied by back suction in the fuel line 21. 4 I

` In orderto afford high fuel economy ina carburetor of the type described, some form of fuel or lecognomizer valve is necessary. With reference to" Fig. 2 such a valve is represented at 455i This'valve is normally closed against its' seat 46 by compression spring 47.

i vIt is disposed in passage 28 between the fuel chamber Band the throat opening'27 of the fuel venturi or vnozzle A. When the valve i is thus seated, as illustrated in Fig. 2, all

of the fuel mustpass through a restricted opening 48 in the valve. `When, however, the valve is open against the spring 47 as by pressure..` upon itsrstem H, the valve will move away fromv the seat and in effect remove the restriction 48, so that a greater quan# position of the control throttle 13 the lvalve is actuated by cam50 Carried on the shaft 51 of the throttle valve and functions to open valve 45 when the throttle valve 13 approaches full throttle o ening.

The sliding t between stem H and its supportingl carburetor body part A52 may permit with the induction passage above the throttle 13 which is at all times subjected to manifold depression regardless of throttle position and has its opposite end communicating with that Space immediately surrounding the circumferentialgrooved part 54 of stem H. Air may thus be removed and conducted away before it may co-mingle with the fuel in the fuel conducting passage. i

In Fig. 8 we have shown with the fuel Venturi tube A; As the velocity of theair drawn through .the tube during operation is relatively high, a hissing sound occurs which is sometimes very noticeable particularly on a well muiiied engine. The silencer eectively stops this hissing without impairing the suction multiplying characteristicof the venturi. It comprises a casing 55 having a detachable end plate 56 which casing surrounds the inlet orifice 26 of the Venturi tube or nozzle. The casing hasa plurality of spaced apart openings 57 -in its side wall through which all of the air admitted to the Venturi tube must pass. The casing 55 is clamped between the carburetor body and the adjacent face of the hexagonal enlargement at the inlet end of the tu e'A. To permit assembly the end plate 56 is removed.

In operation our improved carburetor maintains a substantially uniform depression in the induction chamber C by virtue of the spring operated secondary air valve 12. Means for adjustingthe air valve is provided in an adjustment thumb screw 60 by means a silencer for use ido be controlled to exert pressure againsta maj or .spring 62 which tends to close the valve but yields to atmospheric pressure upon depression in the induction chamber.

The carburetor functions to lift fuel from the main supply tank 23 directly to the throat of the fuel venturi or nozzle A where it comingles with the primary air passing through the venturi and is delivered into the induction chamber in the form of va highly atoniized dition of depression withinthe fuel chamber and passages 28 and 21, the liquid fuel in the chamber and passages, particularly in warm weather, may vaporize rapidly thus forming bubbles of gas in the liquid fuel, which if allowed to pass through the fuel noz zle or venturi A in slugs or large bubbles momentarily shuts off the fuel supply to the induction chamber C causing erratic carburetor performance. Some air also seeks its way into the fuel chamber, usually finding its way into the chamber through tube 21,- from the supply tank, though at times through an inadequate seal as between the mechanical parts of the chamber. Heretofore all gas in the fuel chamber or in the fuel system has been withdrawn through the fuel venturi or nozzle A accompanied by a spatmodic mo-mentary depleting of the richness of the fuel mixture. This condition has been the cause of unsatisfactory performance in many types of carburetors and particularly vacuum feed carburetors wherein fuel is maintained constantly under depression.

A carburetor constructed as illustrated and described herein will function wholly without any disturbance to the fuel mixture, as

fall surplus gas formed and air admitted to 'chamber B 1s withdrawn through passage la by virtue of the relatively high depression in passage E caused by the functioning of the air venturi D.

lh-en all of the gas up to the plane of inlet 43 of passage E has been thus withdrawn a very slight quantity of fuel may pass through the passage E where it is delivered into the induction chamber C and becomes useful as part of the fuel mixture. The amount of fuel however, so admitted to th-e induction chamber is so small that its presence is not. noticeable in the operation of the carburetor. Also, air seeking its way to the fuel passage 28 around the valve stem H, even though the parts be considerably worn, is removed before it reaches the passage through the passage- F wherein a higher degree of depression is normally maintained than that in passage 2S.

The maintenance of an air cushion above the level of fuel in fuel chamber B under diaphragm 24 and the air cushion above the lower rim of inlet 33 cooperate to prevent the decrease or entire shutting off of fuel to the nozzle A during acceleration and the accompanying back suction in the fuel line 21, which is caused by the inertia of fuel therein as the vehicle moves forward. The air cushion above the mouth of inlet 33 readily expands upon the creation of back suction in the fuel line so that the fuel then in the lower region 32- of the fuel chamber is undisturbed, except that during acceleration the fuel has a tendency to shift toward the wall of the fuel chamber due to its inertia which exposes a part of the mouth of inlet 33 to air. This air is quickly drawn up through the fuel i valve where it unites with air in the upper part of the fuel chamber beneath diaphragm 24 to relieve depression therein and hence permit the still further lowering of the .fuel line in the fuel chamber as fuel is drawn through passage 28 to the fuel nozzle. The air cushion formed beneath the diaphragm 24 operates similarly to the air cushion formed in the lower region of the fuel chamber in that it expands upon subjection to depression from the throat of the fuel nozzle and permits fuel to be withdrawn therefrom.

The quantity of fuel which may be drawn through nozzle A during that time when back suction is maintained in the fuel line 21 is dependent upon the size of the fuel reservoir forming a part of the fuel chamber B immediately beneath the plane of the inlet 43 of passage E. Immediately upon the ceasing of back pressure during acceleration the fuel chamber will resume normal operation and the levels of fuel in both the lower and upper regions will lie at the mouth of inlet 33 and at the opening 43 of passage E respectively.

It is apparent, therefore, that the carburetor fuel chamber is divided into two separate parts by the valve 20. The upper region from which fuel is drawn directly to the fuel nozzle A is maintained under a constant depression in pressure during normal operation. This depression is substantially equivalent to about 3G inches of gasoline in a manometer tube. The lower part or region 32 of the fuel chamber is subjected normally to a depression of about 10 inches of gasoline or the equivalent to the actual fuel lift. During acceleration the back suction in the fuel feed line 2l may shut off the flow of fuel to the lower region 32 of the fuel chamber but because of the air cushion formed therein, which is expansible, fuel may continue to flow up through inlet 33 and the fuel valve 20 into the upper part of the chamber where it is available for delivery to the nozzle A. As the fuel in region 32 shifts by its own inertia during acceleration and as it is withdrawn, air is drawn into the upper region of the carburetor to further expand the air cushion formed in the upper chamber and assure free flow of fuel to the nozzle A through passage 28.

lVhile we have herein illustrated an air cushion in the lower region 32 of the fuel chamber to assist in overcoming the effect of back suction in the fuel line upon delivery of fuel to the nozzle A, if desired a check valve, preferably of the hanging lapper valve type may be placed within the chamber against the inlet opening from the low level supply tank to prevent the actual back flow of fuel or gas from the chamber into the fuel intake pipe during rapid acceleration.

lVe have thus provided a carburetor of the vacuum feed type which will operate smoothly and entirely without irregularities in the delivery of fuel mixture.

What we claim is new and desire to secure 'by Letters Patent of the United States is:

' l. In a carburetor, an induction chamber,

draw gas from said fuel chamber, the passage between the throat .of said Venturi tube and said fuel chamber offering relatively high resistance to the passage of fuel therethrough and relatively low resistance to the passage of air therethrough.

2. In a carburetor, an induction chamber, a fuel chamber, a suction multiplying nozzle for delivering fuel from the fuel chamber to the inductionchamber, a venturi tube having one end extending into the induction chamber, a passage interconnecting the throat of the Venturi tube with the upper region ofthe fuel chamber and coperable by induction chamber depression to withdraw air from the fuel chamber, and a pin disposed within said passage for restricting the passage to offer relatively high resistance to the passage of fuel therethrough and low resistance to the passage of gastherethrough.

3. In a carburetor having an induction chamber and a fuel chamber, means for withdrawing gas from the fuel chamber comprising a Venturi tube having one end communicating with the induction chamber, a passage interconnecting the throatof the Venturi tube and the upper region of the fuel chamber, and a restriction disposed within said passage to offer relatively high resistance to the passage of fuel therethrough and relatively low resistance to the passage of gastherethrough.

4. In a carburetor, an induction chamber, a fuel chamber, a fuel supply passage, a fuel valve controlling the admission of fuel to the chamber, means for withdrawing liquid fuel from the fuel chamber, means for withdrawing gas from the fuel chamber including an air withdrawal passage communicating with the upper region of the fuel chamber, and

' means associated with the fuel valve for deflecting fuel as it enters the chamber from said fuel supply passage.

5. In a carburetor, an induction chamber, a fuel chamber, means operable by induction chamber depression to conducty fuel from the fuel chamber to the induction chamber, a valve for controlling the quantity of fuel accessible to said induction chamber having a valve stem exposed to the atmosphere'and apassage communicating at one end with the drawn-to 'preclude its admission to the fuel stream.

6. In a vacuum feed carburetor, an induc-Y tion chamber, a fuel vchamber and suction multiplying fuel nozzle for said induction chamber, a passage interconnecting the fuel inlet of said nozzle and the fuel chamber, a

fuel valve disposed in said passage to control the quantity of fuel passing therethrough, said valve having an actuated stem extendingI exteriorly of the passage, and

means for maintaining the space about said stem beyond said passage under a constant depression to prevent the passage of air about the stem into the fuel passage.v

7. The combination in a carburetor, a fuel nozzle having the form of a suction multiplying Venturi tubel forming a primary air inlet of the carburetor, a closed fuel chamber, a passage interconnecting the fuel chamber and the throat of the Venturi tube through which fuel may be drawn to the fuel chamber from'a low level supply tank, a throttle to control the delivery of fuel mixture from said carburetor, a fuel valve interposed in said passage between the fuel chamber and the nozzle and operable by said throttle to partially restrict the fuel passage at predetermined positions of the throttle valve and means for withdrawing gas f ormed in said fuel chamber prior to the admission of the fuel to the nozzle.

8. In acarburetor wherein fuel is drawn from a fuel chamber to theinduction chamber of the carburetor by suction greater than induction chamber depression, a throttle valve for controlling'the delivery of fuel1 from the fuel chamber by suction greater than that employed for inducing the ow of fuel fromsaid fuel chamber to said induction chamber.

9. In a carburetor wherein fuel is lifted from a low level supply tank to the carburetor fuel nozzle by engine suction, a fuel chamber, a passage extending from a'relatively low point of said chamber to said nozzle, a pressure responsive valve to control the flow of fuel to the chamber, means for maintaining an air` cushion .therein below said fuel nozzle therefrom during the existence Of back suction in the low level tank fuel feed line, caused by acceleration.

- 10. In a fuel lift carburetor having an inl duction chamber and a suction multiplying fuel nozzle for lifting fuel from a low level supply tank to the carburetor by induction chamber depression, a closed fuel chamber, a pressure responsive valve for controlling the flow of fuel to the chamber, a fuel feed pipe interconnecting the fuel chamber and the supply tank, and a passage leading from the fuel chamber to said nozzle, said fuel chamber having an air cushion formed therein below said valve to permit withdrawal of fuel to said nozzle through said valve and said passage during the existence of back suction in the fuel feed pipe, caused by acceleration.

1l.' In a fuel lift carburetor having an induction chamber and a suction multiplying fuel nozzle for lifting fuel from a low level supply tank to the carburetor by induction chamber depression, a closed fuel chamber, a pressure responsive fuel valve in said chamber, a fuel feed pipe interconnecting the fuel chamber and the supply tank, a passage leading from the fuel chamber to the fuel nozzle, means for maintaining a constant air cushion in the fuel chamber below said valve whereby the air cushion may expand during the existence of back suction in the fuel feed line caused by acceleration to permit the withdrawal of fuel through said valve and said passage to the fuel nozzle.

12. In a fuel lift carburetor having an induction chamber and a suction multiplyingI fuel nozzle for lifting fuel from a low level supply tank to the carburetor by induction chamber depression, a closed fuel chamher, a fuel valve in said chamber, a fuel feed pipe interconnecting the fuel chamber and the supply tank, a passage leading from the fuel chamber to said nozzle, said fuel chamber having an air cushion formed therein above said valve to permit withdrawal of fuel to said nozzle through said passage during the `decrease or cessation of the iow of fuel to the chamber due to back suction, caused by acceleration, and other meansl associated with the fuel chamber for admitting air to said cushion during acceleration to permit the withdrawal of part or all of the fuel from the chamber to the nozzle.

13. In a fuel lift carburetor having an induction chamber and a suction multiplying fuel nozzle for liftingfuel from a low level supply tank to the carburetor by induction chamber depression, a closed fuel chamber,

g a fuel valve` in said chamber, a fuel feed pipe interconnectingthe fuel-chamber and the suplply tank, a passage leading from the fuel chamber tothe fuel nozzle, means for main- #taininga constant air cushion in the fuel chamber above said valve whereby the air cushion may expand, during the decrease or cessation of fuel flow to the fuel chamber due tol back suction in the fuel feed line caused vby acceleration, lto permit the Withdrawal of chamber depression, a closed fuel chamber, v

a fuel valve in said chamber, a fuel feed pipe interconnecting the fuel chamber and the supply tank, a passage leading from the fuel chamber to the fuel nozzle, means for maintaining a constant air cushion in the fuel chamber above said valve whereby the air cushion may expand, during the decrease or cessation of fuel iow to the fuel chamber due to back suction in the fuel feed line, caused by acceleration, to permit the Withdrawal of fuel through said passage to the fuel nozzle, and other means including an air cushion below said valve associated with the fuel chamber for increasing the pressure in said first named air cushion to permit the withdrawal of any part or all of the fuel from the fuel chamber to the nozzle.

15. In a carburetor of the type adapted to lift fuel from a low level supply tank to the carburetor by suction derived from the induction passage of the carburetor, a fuel valve located in the fuel passage Way, an expansion chamber between the fuel valve and 100 the low level supply tank adapted to accumulate gas or air from the incoming fuel, said expansion chamber being closed to atmosphere and being normally under a de-l pression measured by the actual fuel lift,

the expansion of the gas or air in said chamber being adapted. to permit a substantially continuous flow of fuel or gas from the expansion chambei` past the fuel valve despite cessation of the How of fuel to the expansion chamber between the fuel valve and the low e level supply tank adapted to accumulate gas or air from the incoming fuel and closed to atmosphere and normally under a depression measured by the actual fuel lift, a second ex-l pansion chamber and fuel valve adapted also to accumulate gas or air from the incoming fuel and being normally under a depression measured by the suction derived from the induction passage of the carburetor, said-first named expansion chamber adapted to permita substantially continuous iow of fuel or gas therefrom past the fuel valve despite cessation of the flow of fuel to the expansion cham- Y,

- ber due to back suction created during acceleration, said second named expansion chamber being adapted to permit the Withdrawal .of fuel from above the fuel valve to the induction passage of the carburetor during that time when fuel is not passingI through the fuel valve.

.17. In a carburetor of the fuel lift type'- atmosphere, a second expansion chamber in the -passage Way above the fuel valve, said first named expansion chamber being so constructed as to permit the passage of air therefrom to the second named-expansion chamber during rapid acceleration accompanied by' shifting of the fuel -in the first named eXpansion chamber due to inertia whereby fuel may be drawn from the second named expansion chamber into the induction passage during the accelerating periodF y18. In a carburetor, anl induction chamber, means for maintaining a substantially constant depression in said chamber, a fuel chamber, a fuel nozzle operable by induction chamber depression to conduct fuel from the fuel chamber to the induction chamber, and a Venturi tube having one end communicating with the induction chamber and having its throat communicating with the upper region of the fuel chamber to Withdraw gas from said fuel' chamber, and removable and adjustable means in the passage between the throat of said Venturi tube and said fuelv chamber offering relatively high resistance to the passage offuel therethrough and relatively loW resistance to the passage of air therethrough.

'19. In a carburetor having an induction 'chamber and a fuel chamber, means for fvith- Vso drawing gas from the fuel chamber comprising a Venturi tube having one end communieating with the induction chamber, a passage interconnecting the throat of the Venturi tube and theupper region of the fuel chamber, and a restriction disposed in the passage substantially throughout the length of, ysaid pasage toI offer relatively high resista-nce to the passage of fuel therethrough and relatively low resistance to the passage of gas therethrough. l

20. In a carburetor wherein fuel is lifted from a 10W level supply tank to the carbu-` tioned in said chamber producing an air cushpassage to the fuel nozzle therefrom during the existence of back suction in the low level tank fuel feed line, caused by acceleration.

21. A fuel lift carburetor comprising an induction chamber, a fuelsupply chamber, means for transferring liquid'fuel from the fuel supply chamber to the induction chamber and creating a depression in the' fuel supply chamber, and means for transferring fluid from the fuel supply chamber at a point above the liquid fuel outlet to the induction chamber, the latter said transferring means 1 being of relatively low liquid capacity and of relativelyl high gaseous capacity so as to maintain the liquid outlet immersed.

22. A fuel lift carburetor comprising an induction chamber, a fuel supply chamber,

suction means for transferring.I liquid fuel from the fuel supply chamber to the induction chamber and thereby create a depression in the fuel supply chamber, suction means communicating with the fuel supply chamber at a' point above the liquid fuel outlet and with the induction chamber, the latter suction means having a relatively loW liquid capacity so that liquid Which may pass therethrough has no objectionable effect on the loperation of the carburetor, and having a relatively high gaseous capacity Whereby the fuel supply chamber is sufficiently freed from vapors so that the supply of liquid' fuel to the first said suction means is continuously maintained.

23. A fuel lift carburetor comprising an induction chamber, a fuel supply chamber adapted to contain fuel up to a varying level depending upon temperature, pressure and nature of the fuel, means 'for transferring liquid fuel from the fuel supply chamber to the induction chamber, and means for transferring vapor or liquid from the fuel supply chamber to the induction chamber,

depending upon the level of liquid fuelfthere- 1n.

24;. A fuel lift carburetor comprising an induction chamber, a fuel supply chamber, a valve controlling the supply of fuel to the fuel supply chamber in accordance with the depression therein, means for vtransferring liquid -fuelfrom a low point of said fuel supply chamber to the induction chamber, and meansl for transferring fluid from an intermediate point of the fuel supply chamber to the induction chamber, thereby maintaining a vapor space n the upper part of the fuel supply chamber and a liquid space in the lower part of said fuel supply cham-vber.

25. fuel lift carburetor comprising an induction chamber,'a fuel supply chamber,

means for maintaining a substantially constant depression therein, 'a Venturi tube adapted to Withdraw liquid fuel from a low point of said fuel supply chamber into the induction chamber, and a Venturi tube for withdrawing fluid from an intermediate point of the fuel supply chamber into the induction chamber, thereby maintaining a vapor space in the upper part of the fuel supply chamber and a liquid space in the lower part of said fuel supply chamber.

26. A fuel lift carburetor comprising anv induction chamber, a fuel supply chamber adapted -to operate with a fluctuating liquid level, suction means for transferring liquid fuel from the fuel supply chamber to the induction chamber and thereby create a depression in the fuel supply chamber, suction -means communicating with the induction chamber and with the fuel supply chamber at a point above the liquid fuel outlet and within the range of the fluctuating liquid level so that liquid and vapor are drawn therethrough at different times, the latter suction means having relatively low liquid capacity so that the liquid passed therethrough has nol objectionable effect on the operation of the carburetor, and having a relatively high gaseous capacity whereby the fuel supply chamber is suiiiciently freed from vapors so that the supply of liquid fuelV to the first said suction'means is continuously maintained.

27. A fuel lift carburetor comprising an induction chamber, a fuel supply .chamber adapted to contain fuel up to a Varying level depending upon temperature, pressure and nature of the fuel, means for transferring liquid fuel from the fuel supply chamber to the induction chamber, and means for transferring vapor from the fuel supply chamber to the induction chamber when the liquid level falls below 'a certain point.

In witness whereof, we hereunto subscribe our names this 9th day of October, 1928.

CLIFFORD C. BRADBURY. ROBERT F. BRACKE.

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