US3540701A

US3540701A - Packed bowl,positively scavenged,weir type carburetor

Info

Publication number: US3540701A
Application number: US794703*A
Authority: US
Inventors: Arthur M Brenneke; Errol J Gay
Original assignee: TRW Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1969-01-28
Filing date: 1969-01-28
Publication date: 1970-11-17
Anticipated expiration: 1987-11-17

Description

O United States Patent [72] Name A u M, B h 3,059,910 10/1962 Moriya 261/72 New c n 1 m 3,189,330 6/1965 Newman 261/34.l Errol .1. Gay, Grosse Point, Michigan FOREIGN PATENTS 1 1 pp 794,703 485,921 5/1927 Germany 261 /72 1 Flled 111114811969 524,293 4/1955 Italy 261/36.1 [45 Patented Nov. 17, 1970 [73] Assign TRW Inc. Primary Examiner-Tm R. M1les Ckvehnd Ohio Attorney-H111, Sherman, Merom, Gross and S1mpson a corporation of Ohio I ABSTRACT: A carburetor bowl having a packing providing 5 PACKED BOWL POSITIVELY SCAVENGED, WEIR small interstices receiving liquid fuel and maintaining the TYPE CARBURETOR level relatively unaffected by d1sturb1ng forces caused by veh1- cle motion. An overflow in the bowl is connected by a 9 Claims, 1 Drawing Fig.

scavengmg 11ne to a vapor separator. A vacuum l1ne conducts US. Cl.

vapor from the vapor separator to an air intake and 261/72 creates air flow through the scavenging line from the bowl to In. C'- ..F02m the vapor separator A diversion valve is connected the Fozm 7/06 base of the vapor separator, a fuel tank and the inlet side of a [50] Field of Search 261/S.P., f l Pump and is operated by a fl in the vapor separator so 70 that liquid fuel travels through the diversion valve to the pump selectively from the vapor separator or the fuel tank, depend- [56] References Cited ing on the level of liquid fuel in the vapor separator. A vacuum UNITED STATES PATENTS regulator limits the vacuum established in the vapor separator 1,093,718 4/1914 Myers 261/70 and bowl by the vacuum line. A pressure or flow regulator act- 2,768,819 10/1956 Bodine 26l/72X ing between the pump and the bowl limits recirculation of 3,020,030 2/1962 Capehart 26l/S.P.UX fuel.

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a P -I- Patented. Nov. 11, 1970 v 3,540,701

S INVENTOR. \&

PACKED BOWL, POSITIVELY SCAVENGED, WEIR TYPE CARBURETOR BACKGROUND OF THE INVENTION This invention relates to a packed or baffled floatless bowl for a carburetor; More specifically, the invention relates to an arrangement for controlling the level of fuel in such a carburetor bowl. I

A conventional carburetor employing a float-controlled bowl is subject to the disadvantage that vehicle motion under certain conditions makes the fuel slosh about in the bowl, causing momentary variations of fuel level and gravity head acting on metering orifices. Thus, the carburetor may deliver momentarily, either excessively rich or lean air/fuel mixtures to the engine, presumably contributing to undesirable exhaust emissionsand air pollution. The use of packing in the carburetor bowl will prevent the fuel therein from bouncing about with certain vehicle movements. With packing in the bowl to eliminate sloshing and a weir or overflow to eliminate the inherent level variation ofthe float and float valve mechanism, a precise level of fuel in the bowl is maintained which is required for optimum operation of the carburetor.

An object ofthe present invention is to provide an improved carburetor of the floatless type.

A further object is to provide an improved carburetor with a bowl filled with packing for preventing the liquid fuel from sloshing about with certain vehicle movements. An overflow is associated with the bowl at the desired fuel level, and the fuel above the overflow is positively scavenged from the bowl.

Other and further important objects of this invention will become apparent from the attached drawings and the detailed description following the brief description of the drawings.

SUMMARY OF THE INVENTION The present carburetor assembly comprises a packed bowl, an overflow therein at the desired fuel level, a scavenging line leading from the overflow, a vapor separator connected with the scavenging line, and a vacuum line connecting engine air intake with the vapor separator for conducting fuel vapor from the separator to the air intake and for creating air flow in the scavenging line to enable the latter to aid the overflow in maintaining a given level of fuel in the bowl. A diversion valve is connected with the base of the vapor separator, a fuel tank, and the inlet of a fuel pump that supplies fuel to the bowl. A float operating in the liquid fuel in the vapor separator controls the diversion valve so that liquid fuel is fed through the diversion valve to the pump selectively from the vapor separator or the fuel tank.

BRIEF DESCRIPTION OF THE DRAWING The single FIG. is an elevational view, partly sectional and partly diagrammatiq of the carburetor assembly of the present invention.

PREFERRED EMBODIMENT OF THE INVENTION A covered unvented carburetor bowl contains a packing 11 which is distributed throughout the bowl while providing space throughout the bowl for liquid fuel such as gasoline. The packing 11 is preferably composed of steel balls, although it may also be composed of felt, porous solid or foam plastic or the like components or material which will provide small interstices for liquid. The packing 11 may also take the form of an aluminum block having openings providing a labyrinth preventing sloshing of the fuel.

A weir 12 is positioned in the carburetor bowl 11, resting on the base thereof. The weir 12 comprises a vertical cylindrical wall 13 having a horizontal radially outwardly directed flange 14 at the top thereof. The weir 12 also comprises a cover 15 which is positioned over the flange 14 and in slightly spaced relation thereto. The weir 12 has a bottom 16 to which is connected one end-of a scavenging line 17. The other end of the scavenging line 17 is connected to a vapor separator 18 at an intermediate or upper region thereof.

An engine air intake or manifold .19 is secured alongside the carburetor-bowl 10 and carries at its .upper end an air cleaner 20 through the perimeter of which air is admitted to intake 19 and flows downwards therein. The intake 19 has a venturi section 21 which is spaced from and below the air cleaner 20. Below the venturi section 21a throttle 22 is pivotally mounted in the air intake 19. A jet 23 extends from a region of the carburetor bowl 10 below the top 15 of the weir 12 into the air intake 19 above the venturi section 21 and below the air cleaner 20. Above thejet 23 and below the air cleaner 20 is an impact or balance tube'24 which is connected with a region of the bowl 10 above the top 15 of the weir 12 and extends into the air intake 19.

A vacuum line 25 has one end connected to the airintake 19 just below the throttle 22 and the other end connected through a vacuum regulator 26 with an upper region or the top of the vapor separator 18. The vacuum regulator 26 includes a spring operated valve 260 urged to an open position as shown with respect to an air opening in the top of the vapor separator 18. The valve 260 has a tiny orifice 26b which keeps the vacuum line 25 connected with the vapor separator 18, even when the valve 260 may be closed because of high vacuum in the vacuum line 25. The purpose of the orifice 26b is to maintain a connection between the vacuum line 25 and .the scavenge line 17 through the vapor separator 18 and thus to insure minimumneccssary scavenge air flow through'the carburetor bowl 10. Alternatively, a valve may be omitted from the vacuum regulator 26 which may employ only a tinyflxed orifice as a'connection between the vacuum line 25 and the vapor separator 18.

The vapor separator 18 has a base 27 which is provided with an upper outwardly extending flange 33 which rests on top of the base 27. The valve part 31 has openings 34 distributed about an intermediate region. The passage 29 is connected with an upper regionof the chamber 28 located between the flanges 32v and 33 of the valve seat 31. The passage 30 is connected with a lower region of the chamber 28 located below the valve seat 31.

The stationary valve seat 31 forms a part of a diversion valve 35 which also includes a movable valve part 3511 positioned within the stationary valve seat 31. The movable valve part 35a comprises an upper conical part 36, a lower conical part 37, and a stem 38 which spaces the conical parts 36 and 37 from one another and'is attached to them at their small ends. A float 39 is secured to the upper end of the movable valve part 35a, [.e., to the .large end of the upper conical part 36. Thus, the level of liquid fuel in the vapor separator 18 in which the float 39 rides determines whether the upper conical portion 36 of the movable valve part 35a engages the upper end of the stationary valve seat 31 or the lower conical portion 37 engages the lower end of the valve seat 31.

The passage 30 in the base 27 of the vapor separator 18 is connected vbya line 40 with a supply tank 41, which has an air vent 41a to the atmosphere. The passage 29 in the base 27 is connected by a line 42 with the inlet side of a pump 43. The pump is connected at its outletside by a line '44 and a pressure or flow regulator '45 with a region of the carburetor bowl [0 below the top 15 ofthe weir 12.

In operation,- the liquid fuel in the carburetor bowl 10 is maintained as indicated by the reference character 46 at the level of the top 15 of the weir 12, which constitutes an overflow for the liquid fuel. Thus, liquid fuel flows between the top 15 and the flange 14 into the weir 12 and out through the bottom thereof in the scavenging line 17 to the vapor separator 18. For proper operation of the jet 23, it is very important that the liquid level 46 of the fuel be maintained at the level of the top 15 ofthe weir 12. The scavenging line 17 plays a most imby virtue of its connection with the vacuum line 25 through the upper region of the vapor separator 18.

The vapor separator 18 has fuel vapor in its upper region and liquid fuel in its lower region. The fuel vapor is conducted from the vapor separator 18 through the vacuum line 25 to the air intake or manifold 19. Liquid fuel in the vapor separator 18 passes through the openings 34 in the seat member 31 and the passage 29 in the base 27 to the line 42 leading to the intake side of the fuel pump 43, by which it is returned to the carburetor bowl 10. In order that fuel vapor in the vapor separator 18 may not be drawn into the pump 43 through the passage 29 in the base 27 and the line 42, lowering of the level of liquid fuel in the vapor separator 18 below a certain point lowers the float 39 until upper conical portion 36 of the movable valve part 350 seats against the upper end of the stationary valve part 31. In this position the vapor separator 18 is cut off from the interior ofthe stationary valve part 31, and thus from the pump v43, which is connected with the interior of the stationary valve part through the openings 34 in the seat member through openings 34, passage 29, and line 42 leading to the intake side of the pump 43. In this position of the movable valve part 35a, the lower conical portion 37 is spaced from the lower end of the stationary valve seat 31, and the fuel tank 41 is connected through the line 40, the passage 30, and the chamber 28 with the interior ofthe valve seat 31 and thus with the pump 43. Consequently, the pump draws fuel from the tank 41. When the level of liquid fuel in the vapor separator 18 rises sufficiently the float 39 will rise to move the upper conical portion 36 of the valve part 35a away from the upper end of the seat member 31 and the lower conical portion 37 into engagement with the lower end of the seat member 31. Engagement of the conical portion 37 with the lower end of valve part 31 blocks flow of liquid fuel from the supply tank 41 to the interior of valve member 31 and thus to the pump 43. Thus, fuel no longer is sucked from the supply tank 41 into the pump 43. At the same time, movement of the upper conical portion 36 away from the top of the valve member 31 connects the vapor separator 18 with the interior of the valve seat 31 and thus with the pump 43. The pump now draws liquid fuel from the separator 18.

The use of a packing 11 such as one made of steel balls in the carburetor bowl enables the level 46 of the liquid fuel in the carburetor bowl to stay at the top of the weir 12, re-.

gardless of vehicle motions that might tend to change the level of the liquid fuel. The steel balls also provide a heat sink, which will prevent evaporation ofliquid fuel from the carburetor bowl 10 because of heating when the car is stopped after some period of operation. For accurate maintenance of the liquid level 46 in the carburetor bowl 10, we have found it highly advantageous to provide positive scavenging as is accomplished by the scavenging line 17. The use of the vapor separator 18 with its vacuum line 25 and the diversion valve 35 makes feasible the scavenging of the fuel from the carburetor bowl l0 and return of the scavenged fuel to the bowl, without the use of an auxiliary pump. The vacuum line 25 connects between the vapor separator 18 and the air intake [9 enables the scavenging line 17 to scavenge, and the diversion valve 35 in the base 27 of the vapor separator 18 permits liquid fuel to be returned to the pump 43 while excluding fuel vapor.

The vacuum regulator 26 limits the amount of vacuum exerted upon the scavenging line 17 by the vacuum line 25. Our experience has shown that air flow in the scavenge line 17 is rather critical. High flow in line 17 reduces pressure on the bowl 10 above the liquid fuel as well as in the vapor separator 18. Thevacuum for optimum flow in line 17 for several engines tested is about two or three inches of water. Greater air flow in the scavenge line 17 tends to cause the fuel to percolate or boil, and this is an undesirable occurrence.

The purpose of the regulator 45 is to reduce recirculation of fuel from the bowl 10 through the scavenge line 17, the vapor separator 18, the pump 43, and its lines 42 and 44 back to the carburetor bowl. to a minimum needed for a satisfactory scavenging by the line 17. Holding fuel recirculation to a minimum minimizes heating of the fuel caused by recirculation. I

it will be understood that the illustrated embodiment of the invention has been used for illustrative purposes only and that various modifications and variations of the present invention may be effected without a departure in the spirit and scope of the novel concept. thereof.

We claim: I

1. An assembly comprising a carburetor bowl, a packing distributed throughout the bowl while leaving spaces for liquid fuel throughout the bowl, an overflow positioned in the bowl intermediate the top and bottom thereof, an air intake adjacent the carburetor bowl, means connecting the bowl with the air intake to cause the passage of air therethrough to draw fuel from the bowl into the air intake, a fuel pump having its outlet connected with the carburetor bowl, a scavenging line connected with the overflow in the bowl, and vacuum means connected with the air intake for pulling fuel through the scavenging line and returning it to the inlet side of the pump.

2. Apparatus for scavenging a floatless carburetor bowl that has a weir, is filled with interstice-forming packing, is connected by a jet and an impact tube with an air intake having a throttle, and is supplied by a pump, said apparatus comprising a vapor separator, a scavenging line adapted to connect the weir with an upper region of the vapor separator, for conducting fuel and air from the weir to the vapor separator, a vacuum line adapted to connect a region of the air intake downstream of the throttle with an upper region of the vapor separator for establishing a vacuum in the scavenging line, means including a valve for passing liquid fuel from the bottom of the vapor separator to the inlet side of the pump, and means responsive to the level of the liquid fuel in the vapor separator for controlling opening and closing of the valve.

3. An assembly comprising a carburetor bowl, a heat sink packing distributed throughout the bowl while leaving spaces for liquid fuel throughout the bowl, an overflow positioned in the bowl intermediate the top and bottom thereof, an air intake, means connecting the air intake with the carburetor bowl for introducing fuel from the bowl into the air intake, a scavenging line connecting the overflow in the carburetor bowl with the vapor separator for conducting fuel from the overflow to the vapor separator, a vacuum line connecting the vapor separator with the air intake for establishing a vacuum in the scavenging line, a fuel pump having its outlet connected with the carburetor-bowl, means including a valve for passing liquid fuel from the vapor separator to the inlet side of the pump, and means responsive to the level of liquid fuel in the vapor separator for controlling the opening and closing of the valve.

4. An assembly comprising a carburetor bowl, a packing distributed throughout the bowl while leaving spaces for liquid fuel through the bowl, an overflow positioned at an intermediate level in the bowl, an air intake adjacent the carburetor bowl and having a venturi section, a throttle positioned in the air intake line downstream of the venturi section, an impact tube extending into a region of the air intake line upstream from the venturi section from a region of the bowl above the overflow, a jet extending into the air intake between the impacttube and the venturi section from a region of the bowl below the overflow, a vapor separator, a scavenging line connecting the overflow in the carburetor bowl with an upper region of the vapor separator for conducting fuel and air from the overflow to the vapor separator, a'vacuum line connecting an upper region of the vapor separator with a region of the air intake downstream of the throttle for conducting fuel vapor from the vapor separator to the air intake and for establishing a vacuum in the scavenging line, a fuel pump having its outlet connected with the carburetor bowl, a fuel'tank, valve means connected with the inlet of the fuel pump, the fuel tank, and the lower end of the vapor separator, and means responsive to the level of the liquid fuel in the vapor separator for actuating the valve means to enable it to pass liquid fuel to the fuel pump selectively from the vapor separator or the fuel tank.

5. An assembly according'to claim 4, comprising a vacuum regulator associated with the vacuum line for limiting the vacuum exerted on the vapor separator and bowl and thereby on the scavenging line.

6. An assembly according to claim 5, comprising a pressure or flow regulator connected between the carburetor bowl and the outlet of the pump.

7. An assembly according to claim 4, the vapor separator including a base having a chamber formed therein and opening into the top of the base, the base further having a first passage communicating'with an upper region ofthe chamber and connected with the inlet side of the pump and a second passage communicating with a lower region of the chamber and connected with the fuel tank, the valve means being a transfer valve comprising a stationary valve seat and a movable valve part, the valve seat being hollow and having a bottom flange threaded into the chamber, a top flange resting against the top of the base of the separator, and an intermediate region opposite the first passage in the base and having openings providing communication between the first passage and the interior ofthe valve seat, the movable valve part being located therein and comprising a stem and upper and lower conical portions spaced from one another by the stem, the smaller ends olthc conical portions being toward one another, the upper conical portion being seatable against the inner edge ofthe upper end of the valve seat upon downward movement of the movable valve part to close the inside of the valve seat to liquid fuel in the vapor separator, the said downward movement moving the lower-conical portion of the movable valve part away from the lower end of the valve seat and thus permitting fuel to pass from the fuel tank through the second passage in the base of the vapor separator, the chamber in the base, the openings in the valve seat, and the first passage in the base to the pump, the lower conical portion of the movable valve part being seatable against the inner edge of the lower end of the valve seat upon upward movement of-the movable valve part to close the inside of the valve seat to liquid fuel reaching the chamber in the base of the vapor separator through the second passage from the fuel tank, the said upward movement moving the upper conical portion of the movable part away from the upper end of the valve seat and thus permitting liquid fuel to pass from the vapor separator through the openings in the valve seat and the first passage in the base ofthe vapor separator to the pump.

8. An assembly according to claim 7. the means responsive to level of the liquid fuel in the vapor separator being a float attached to the upper end of the upper conical portion of the movable valve part.

9. The assembly of claim I when the packing is composed of small steel balls.