US2796242A

US2796242A - Carburetor

Info

Publication number: US2796242A
Application number: US431138A
Authority: US
Inventors: Jorma O Sarto
Original assignee: Chrysler Corp
Current assignee: Old Carco LLC
Priority date: 1954-05-20
Filing date: 1954-05-20
Publication date: 1957-06-18
Anticipated expiration: 1974-06-18

Description

June 18, 1957 Filed May 20, 1954 J. o. SARTO CARBURETQR 4 Sheets-Sheet 1 INVENTOR. 7? 0. 64711 June 18, 1957 J. o. SARTO v. 2,796,242

CARBURETOR 7 Filed May 20, 1954 4 Sheets-Sheet 4 l if 202 i INVENTOR. E. E1. Jamm 0. 34%

{MW-J44 United rates CARBURETOR Jorma 0. Sarto, Walled Lake, Mich., assignor to Chrysler Corporation, Highland Park, Mich, a corporation of Delaware Application May 20, 1954, Serial No. 431,138

6 Claims. (Cl. 26134) This invention relates generally to internal combustion engines and more particularly to a new and improved liquid fuel carburetor for use therewith.

Liquid fuel carburetors for internal combustion engines v are normally provided with a venturi throat for accomfunction of the magnitude of the venturi air flow rate.

and since this functional relationship is non-linear, certain compensating means are required in order to maintain the fuel-air ratio of the charge within an optimum range of values. In addition, a suitable fuel pumping mechanism may be incorporated in the carburetor for the purpose of pumping a quantity of fuel directly into the venturi air stream to supplement the normal discharge of the fuel discharge nozzle. The pumping mechanism may be positively connected to the carburetor throttle valve linkage mechanism and may be actuated thereby while starting or accelerating the engine by quickly opening the throttle valve.

The fuel which is confined within the working chamber of the throttle linkage actuated pumping mechanism becomes heated during operation of the engine and under certain circumstances may vaporize. The vapor pressure of the gasoline will then force the liquid fuel from the working chamber of the pumping mechanism throughthe pump discharge passage means thus rendering the pumping mechanism ineffective when the throttle linkage mechanism is subsequently actuated. This condition is commonly referred to as a vapor lock.

If the above-described vapor lock occurs while the engine remains idle immediately following a period of sustained operation during which the fuel in the fuel bowl and the working chamber of the pumping mechanism has become heated by the engine, considerable difficulty will be experienced in re-starting the engine because of the inability of the pumping mechanism to discharge liquid fuel within the carburetor throat.

if the vapor lock occurs while the engine is in operation, the pumping mechanism will be ineffective in supplying the required additional liquid fuel to obtain rapid acceleration. It is quite likely that the engine may miss fire under such conditions if an attempt is made to accelerate the engine since the fuel mixture supplied by the carburetor would be too lean to support combustion in the engine cylinders.

Accordingly, it is an object of the present invention to provide a new and improved carburetor of the type described above wherein means are included for eliminating vapor lock.

Another object of the present invention is to provide atent 2,796,242 Patented June 13, 1957 a new and improved liquid fuel carburetor of the type described above which includes an auxiliary fuel pumping mechanism for discharging fuel into the intake air passage in response to movement of the throttle valve, said mechanism including a vent means for evacuating the fuel vapors from the working chamber thereof.

Another object of the present invention is to provide a carburetor of the type forth in the preceding object wherein the pumping mechanism includes fuel intake passage means for conducting fuel from the carburetor fuel bowl to the working chamber of the pumping mechanism, and wherein said passage means is controlled by a one-way valve, said one-way valve including a movable valve element formed of nylon or other suitable material having a similarly low specific gravity. It is contemplated, that this one-way valve will be disposed below the fuel level of the carburetor fuel bowl and will be adapted to become unseated by the hydrostatic pressure of the fuel in the event that the fuel within the working chamber of the pumping mechanism is evacuated as a result of a build-up in vapor pressure as previously described.

Another object of the present invention is to provide a new and improved carburetor of the type previously described wherein the carburetor fuel bowl includes a separate weathering well in communication with the intake passage means for the pumping mechanism, the weathering well being adapted to be supplied with fuel from the fuel bowl proper. It is contemplated that the weathering well will retain a portion of the fuel in a static condition prior to being forced into the working chamber of the pumping mechanism and that this fuel portion will become heated to an elevated temperature while in this static condition thereby driving off the more volatile constituents of the fuel.

Other objects will become apparent from the following description of one particular embodiment of the invention and from the accompanying drawings, wherein:

Figure. l is a-side elevational view of the carburetor of the instant invention;

Figure 2 is a top view of the carburetor of Figure 1;

Figure 3 is a cross sectional view of the carburetor of Figures 1 and 2 taken along the section line 33 of Figure 2;

Figure 4 is a cross sectional view of the carburetor of Figures 1 and 2 taken substantially along the section line 44 of Figure 2;

Figure 5 is a cross sectional view of the carburetor of Figures 1 and 2 taken along the section line 55 of Figure 2;

Figure 6 is a cross sectional view of a lower cast portion of the carburetor of Figures 1 and 2 taken along the section line 66 of Figure 3 and showing the details of the fuel bowl and weathering well portion;

Figure 7 is a cross sectional View of the weathering well portion of the fuel bowl taken along the section line 7-7 of Figure 6; and

Figure 8 is a cross sectional view of a piston element of the carburetor pumping mechanism.

As best seen in Figures 1 and 2, the carburetor of the instant invention comprises an upper cast body 10, an intermediate cast body 12 and a lower cast body 14. The upper cast body it) includes a circular intake duct portion 16 which defines an intake opening 18 extending in a downward direction and which is adapted to accommodate the flow of carburetor intake air to a pair of downdraft throats 2t) and 22 formed in the intermediate housing 12 as best seen in the top view of Figure 2.

The upper cast body 10 further includes a laterally extending base portion 24 which is adapted to cover the upper surface of the intermediate cast body 12. A flange 26 is provided, as shown in Figure 1, about the upper periphery of the intermediate cast body 12. Suitable bolts 23 may be provided, as shown in Figures 1 and 2, for securing the flange 26 to the lower surface of the upper cast body 10. Other bolts 36 may be provided at one side of the upper cast body 1b and may extend through the flange 26 adjacent the cast body 12 and may be threadably received in a suitable threaded aperture formed in the upper surface of the lower east body 14. A flange 32 may be provided, as shown in Figure 1, on the lower peripheral edge of the intermediate cast body 12 which may be formed with a suitable aperture for receiving the shank portion of the bolt 30 therethrough. A suitable gasket material 34 may be provided between the mating upper and lower surfaces of the cast bodies and 12 respectively, as shown in Figure 1.

The intermediate casting body 12 includes a hollow fuel bowl portion 36 and a hollow downdraft throat portion 38 which may be separated by an internal transverse Wall structure 40' as best seen in Figures 2 and 6. The pair of downdraft throats 2t and 22 are cast integrally with the cast body 12 in the floor or bottom section of the downdraft portion 38 thereof as shown at 41 in Figure 6.

The lower east body 14 may be provided with a pair of circular downdraft passages, one of which is shown in Figure 3 at 42, and the other of which is shown at 44 in Figure 4, these passages forming continuations of the downdraft throats Ztl and 22, respectively. These downdraft passages and throats are efiective to define a pair of carburetor barrels for accommodating the flow of the combustible mixture to intake manifold conduits of the internal combustion engine upon which the carburetor of the instant invention is adapted to be mounted. The cast body 14 may be secured to the lower surface of the intermediate cast body 12 by means of bolts 30 and by means of an auxiliary bolt 46, as shown in Figure 1. A suitable gasket material 43 may be interposed between the mating surfaces of the intermediate cast body 12 and the lower east body 14. Suitable bosses 53 may be provided, as shown in Figures 1 and 2, for the purpose of securing the lower cast body 14 to the intake manifold structure of the internal combustion engine.

A throttle shaft 52 extends through the lower east body 14 and intersects the

passageways

12 and 44 thereof, as shown in Figures 3 and 4, and is adapted to be rotated about its longitudinal axis. A pair of circular disc-type throttle valves 54 and 56 may be secured to the throttle shaft 52 within the passages 42 and 44, respectively, and may be rotated therein upon rotation of the throttle shaft 52 about its axis thereby controlling the flow of combusible mixture into the intake manifold of the engine.

The upper cast body 10 is provided with a choke valve shaft 58 which extends transversely across the intake opening 18. and which is adapted to rotate about its longitudinal axis. A choke valve of is secured to the shaft 58 and is effective to control the flow of intake air through the carburetor intake opening 18 upon rotation of the shaft 58. A suitable thermostatic actuating device 62 may be secured to one side of the carburetor upper. cast body 10, as shown in Figure 2, and may be adapted to actuate the choke valve shaft 58 in response to engine exhaust manifold temperature in a conventional manner.

A throttle linkage element 6 may be secured to one end of the throttle shaft 52, as shown in Figure 1, for rotatably actuating the same to selectively-vary the throttle position of the throttle valves 54 and 56 during operation of the engine. An extension 66 is formed on the element 64- and may be secured to one end of another link element 63, as shown in Figure 1. The link 68 extends in a substantially vertical direction adjacent the intermediate cast body 12 and is operatively secured at the other end thereof to a lever element 79. Suitable mounting means 72 may be provided on the upper cast body 10 for adapting the lever element 7ft for oscillatory movement about an axis extending through the central portion of the same. The other end of the lever mem ber may be operatively secured, as shown at 74, to an upper portion of the piston rod element of a carburetor pumping mechanism disposed within the fuel bowl portion 36 of the cast body 12. This pumping mechanism will subsequently be described in particular detail.

The lower east body 14 may be provided with a cored passageway 78 as best seen in Figures 3 and 4. An engine coolant inlet adaptor 80 may be integrally cast to one side of the lower cast body 14 and a suitable engine coolant outlet adaptor 82 may be similarly cast to the opposite side of the lower east body 14, as shown in Figure 2. The

adaptors

30 and 82 are eflective to circulate engine coolant through the cored passages '78 for the purpose of preventing the formation of ice within the passageways 42 and 44. As best seen in Figure 3, the cored passageways 78 extend through the cast structure of the cast body 14 substantially adjacent the peripheral edge of the circular'throttle valves 54 and 56 when the latter are in the closed throttle position. It is apparent that the maximum throttling action will occur about the edges of the throttle valves 54 and 56 while in a position substantially near the closed throttle position and this will be accompanied by a considerable temperature drop in the throttle combustible mixture. The cored passages '78 are therefore formed in the most strategic and advantageous position.

As best seen in Figure 6, the transverse wall structure 40 includes a base structure 84 which is cast integrally therewith and which extends downwardly to the floor structure 41. As best seen in Figure 4, the base struc ture 84 is provided with a flat top surface 36 upon which a small venturi structure 88 may be mounted. The venturi structure 88 includes a small venturi element 90 centrally disposed above the downdraft throat 22 and having a laterally extending mounting portion 92. The extension 92 is provided with a lower surface 94 which may. be positioned upon the upper surface 86 of the base structure 84 and is separated therefrom by suitable gasket material 96. The extension 92 further includes a flat upper surface 98 upon which an auxiliary venturi portion 160 may be positioned, as shown in Figure 4. A suitable gasket material M2 may be provided between the upper surface 98 and the mating lower surface 104 of the venturi portion 1%.

The auxiliary venturi portion 190 and the laterally extending mounting portion 92 may be provided with a pair of aligned bores 106 and respectively, through which a pair of bolts 110 may be respectively received. The threaded ends 112 of the bolts iii) are adapted to be received within the mating threaded apertures 114 formed in the base structure 34, as shown in Figure 4, and are effective to secure the small venturi structure 88 and the auxiliary portion Hit) in a fixed position within the downdraft portion 58 of the intermediate cast body 12. The bolts 110 may each be provided with an axially extending passage 116, as shown in Figure 4, these passages 116 respectively communicating with vertically extending passages 118 formed in the transverse wall structure 4-!) and extending into passages 120 formed in the lower east body 14, the passages 12% each in turn terminating at an idling jet opening 122 formed in each wall of the passageways 44 and 42.

The orifices 122 may be selectively restricted by means of adjustable needles 123 which are threadably received within the wall of the cast body 14. The upper ends of the passages 116, as shownin Figure 4, are exposed to the downwardly directed intake air flow which passes through the intake opening 18 and are intersected by a transverse passage 124 formed in the upper portion of the shank of the bolt 110.

The base structure 84, the extension 92 of the venturi portion 88 andthe venturi portion 100 are each provided with a pair of identical vertically extending openings, one of the pair being designated in Figure 4 by

numerals

126, 128, and 130, respectively. These openings are aligned vertically and are adapted to define a pair of vertically extending fuel wells, one of which is generally designated in Figure 4 by numeral 132.

A perforated hollow tube 134 fixed within a mating aperture in the venturi portion 100 extends downwardly into the fuel well 132. The tube 134 is provided with a hollow central interior, as shown at 136, one end of which extends through the venturi portion 100 and is exposed at 138 to the downwardly directed carburetor intake air in the intake passage 18 of the cast carburetor body 10. A series of perforations 140 are provided at spaced intervals along the tube 134 to provide communication between the hollow interior 136 and the interior of the fuel well 132.

An idling tube 142 is also secured to the venturi portion 100 and extends downwardly into the fuel well 132, as shown in Figure 4. The tube 142 has a hollow interior 144 which communicates with the interior of the fuel well 132 through an opening 146 formed in the lower end of the tube.

The upper end of the tube 142 is provided with an opening 148 which communicates with a passage 150 formed in the supporting venturi portion 100. The passage 150 is adapted to interconnect passage 124 and the opening 116 in the bolt 110 to the interior of the idling tube 142.

A fuel passage 152 is provided as shown in Figure 4, and extends from the base of the fuel well 132 through the plane of the transverse wall structure 40. The extended end of the passage 152 communicates with a main metering jet opening 154 formed in the base of a metering element 156. A threaded end portion of the element 156 may be threadably received in a mating threaded aperture 158 formed in the floor of the fuel bowl defined by the portion 36 of the intermediate case body 12. A plurality of laterally extending passages may be provided at 160 for providing communication between the interior of the fuel bowl and the jet opening 154. A metering rod 162 formed of common piano wire may be inserted longitudinally through the hollow interior of the metering element 156 and may be guided by inwardly projecting guide portions 164 so that the jet opening 154 and the metering rod 162 are longitudinally aligned. The upper end of the rod 162, as viewed in Figure 4, may be operatively secured by means of element 165 to a vertically movable piston element, shown at 166 in Figures 4 and 5, and is movable therewith to selectively restrict and to control the flow of fuel from the fuel bowl through the jet opening 154.

The piston element 166 is slidably disposed within a cylindrical bore 167 and is spring biased in an upward direction by spring 169 as shown in Figure 5.

A main fuel discharge nozzle, shown at 168 in Figure 4, may be secured with a downwardly extending passage 170 formed in the venturi extension 92 so that it terminates at the center of the venturi passageway. The passage 170 communicates with the interior of the fuel well 132 as shown, a passage extension 172 being provided in the venturi portion 100 for this purpose.

A separate small venturi assembly and fuel well assembly of the type described above, may be provided for each carburetor intake barrel. In addition, separate fuel metering jets and metering rods may be provided for supplying each of the respective fuel wells with fuel from the carburetor fuel bowl. The metering rods for each metering jet may be operated in tandem and may each be secured to the vertically movable piston 166.

Referring next to Figure 6, it is seen that the portion 36 of the cast body defines a fuel bowl having two portions thereof, shown at 174 and 176, which are separated by a cast wall structure, shown generally at 178. The wall structure 178 extends vertically from the floor of the fuel bowl and is disposed substantially in a plane which is perpendicular to the transverse plane of the wall struc ture 40.

The relationship between the fuel wells, the bolts and the metering jets may also be best observed from the sectional view of Figure 6. For example, the position of the fuel wells 132 may be determined by the location of the opening 126 in the cast body 12, and the'position of the bolts 110 may be determined by the location of the threaded openings 114.

The wall structure 178, as shown in Figure 6, includes a pair of

cylindrical portions

180 and 182 which define vertically extending

cylindrical bores

184 and 186, respectively. The piston element 166 is slidably received within the bore 184, as shown in Figure 5, and is biased in an upward direction by spring 169 which is seated on the upper end face of a cylindrical insert extending vertically through the floor of the fuel bowl. A suitable vertically extending threaded aperture 192 may be provided in the plane of the wall structure 178 for receiving the insert 190 and may be concentrically situated with respect to the center line of the cylindrical portion 180. The insert 190 may be provided with a central axially extending passage 194 and a transversely extending passage 196 which communicate with a transversely extending passageway 198 formed in the cast carburetor body 14. A vertically extending passageway 200 may be pro vided, as shown in Figure 5, for providing communication between the passageway 198 and the intake manifold of the engine upon which the cast body 14 is adapted to be mounted. The piston element 166 therefore may move vertically in response to variations in the magnitude of the intake manifold vacuum to selectively control the flow of fuel through the main metering jet openings 154.

A cylindrical bore 186 is adapted to slidably receive a piston element 202, as shown in Figures 3 and 5, and is connected to the lever 70 by means of piston rod 76 which extends through the extended portion 24 of the cast body 10. The lever 70 preferably includes the lost motion joint 204 which will permit the lever 70 to raise the piston 202 but which will allow a spring 206 to return the piston 202 to the downward position independently of the movement of the link 68 and the throttle valve shaft 52, said spring 206 being interposed between the piston 202 and the interior surface of the extended portion 24 of the upper cast body 10. The piston 202 and the cylindrical bore 186 defined by the cast portion 182 comprises a portion of a fuel pumping mechanism, the working chamber of which is designated by the numeral 208.

A pair of fuel discharge passageways 210 extends from the working chamber 208 through the floors of the respective

fuel bowl portions

174 and 176 substantially adjacent the plane of the wall structure 178 and communicates with another discharge passageway 212 formed substantially in the plane of the transverse wall structure 40. The passageway 212 extends in a generally upward direction to a cavity 214 formed in the upper surface of the carburetor cast body 12. Nozzle elements 216 are threadably received in each of the respective carburetor barrels within suitable threaded openings, as shown in Figure 3, and are provided with axially extending nozzle openings 218 which provide communication between the cavity 214 and the interior of the respective barrels in the general vicinity of the small venturi assembly 88. A transverse opening is provided in each of the nozzle elements 216, as shown at 220, which are adapted to provide communication between the nozzle openings 218 and the interior of the

fuel bowl portions

174 and 176 through suitable .drain passages, not specifically shown.

As best seen in Figures 3 and 6, a weathering well 222 is disposed at one side of the carburetor fuel bowl and is situated substantially in the plane of the wall structure 17 8. The weathering well 222 is defined by the cast portion 36 of the intermediate cast body 12 and by inwardly extending extensions 224 which are integrally cast with the interior of the cast portion 36. Suitable walls 226 and 228 may be provided, as-showntin Eigure 6, for providinga bridge between the cylindrical cast portion 182 of the walls'tructure 178 and the :extensions224. The bottom of ,the weathering -=well 222 is cconnected to the interior of the working chamber 208 of the carburetor pumping mechanism by suitable passages 23tlfand 232 which are adapted to conduct fuel from the weathering well 2 22 to the interior of the Working chamber .268. A nylon ball check valve element 234 is disposed at the=discharge end.of:the passage 232 and is :adapted to :be moved vertically on "its valve seat to permit the working chamber 268 to be charged. .A similar check valve element 235 may be provided at the discharge .end;of the passage 212. The specific :gravity of the I ball :check valve 234 is such that it may become Funseated by the hydrostatic pressure of the fuel *within the weathering .well 222 to :automatically permit the flow .of 'fuel into the working chamber 208 in the event that the working chamber 208 becomes evacuated.

The

fuel bowl portions

174 and 176 areadapted 'to accommodate a pairiofifloatsnnotiparticulafly shown, which may :be operativelyrconnected to -'a lever 236 pivoted, as shown in 'Figure 3, to 'a transverselyextending .-pin 238, the ends of the pin 238zbeing'held'within suitable recesses 240 and 242 formed in the cast-extensions 244, as shown in Figure 6. The lever 236 is thereby adapted to oscillate about "-the .pin 238 in response to variations in the level of the fuel within the

fuel bowl portions

174 and 178 and may correspondingly adjust the position of a movable valve element 244 disposed in a fuel intake -fitting .246. The fuel level may thereby be maintained at a substantially constant height.

Fuel may enter the weathering well 222 over the walls 226 and 228 which bridge the opening between extensions 224 andthe cylindrical cast portion 182 of the wall structure 178.

As bestsecn in Figure 8, piston rod 76 is provided with an axially extending passageway 248 therethrough which is effective to provide communication between the working chamber and a vent opening 250 situated substantially above the level of the

fuel bowl portions

174 and 176. The piston element proper comprises a cylindrical member 252'secured at the lower end of the piston rod 76 inasuitable manner and a fabric material 254 whichenvelops the cylindrical'member 252. The fabric material 254 is secured between the upper surfaceof the cylindrical member "252 and a washer 256 and is biased in 'a radially outward direction by a helical spring 258 disposed about the periphery of the circular member 252.

The operation of the carburetor of the present invention is as follows:

A carburetor intake opening 18 is adapted to con duct carburetor intake air therethrough and a portion of this air passes through the small venturi openings in the piston 99 of the small venturi assemblies 88. The nozzle 168 is-adapted to discharge a controlled quantity of fuel into the intake air stream at a rate which is proportional to the static pressure drop at the throat of the venturi.

The nozzles 16% are supplied with fuel from the fuel wells 132 which in turn are supplied by the fuel passages 152. The metering jets are adapted to control the rate of fuel flow from the

fuel bowl portions

174 and 176 and to progressively restrict the same when the engine intake manifold vacuum increases in magnitude. The perforated tubes 134 are adapted to emulsify or aerate the liquid fuel within the fuel well 132 and the fuel is discharged in this condition from the fuel nozzle-168.

The metering tubes 148 are effective to'supply the passages 118with fuel from the interior of the fuel wells 132 when the throttle valves 56 and 54 assume a closed throttle position. The fuel then passes through the passages 118 and the passage 12%) in an aerated condition and is discharged at the idlingjet openings 122.

The accelerator linkage mechanism forthe vehicle may be operatively connected to the throttle linkage element 64 -.and 'is :adapted to adjust ithe :position of :the throttle valves S4-and 5-6 tocontrol the rateofsflow ofcombustible mixture through the carburetor throats 2tiandf-22andinto thetengine intake manifold. The movemenbof the linkage element in this rnanner'also causes the :piston202of the carburetor .pumping mechanism to be reciprocated Within the cylindrical bore 186 :byyirtue of:the.linkage connection between ithe :throttle vale shaft 52 .and the piston rod 76.

When the engine :is being started, the vehicle accelerator may be depressed thereby causing the lever member 70 to rotate :about its pivotal :mounting athus causing the lever =member'70 to -rotate.-iso that C'El'lBLlOSlIfIIlOiiOn connection at 204 becomes disengaged. The normally .compressed spring 206 will then depress the piston within the bore 186 independently .of the throttle linkage. This downward movement of the ipiston-zcauses fuel tobe discharged from the workinguc'ha'mber 208 throughthe-passages 210 and 212 :and tosbe ejected'throughthenozzle element 216 into the intake air stream to fa-cilitate start- 1ng.

When the engine'is fturnediotf-aftera period-of sustained operation, :the fuel which remains in the working chamber -2tl8.:has a tendency to become heated by the engine and to vaporize 'before theengine temperture decreases to a value equal to that of the ambient air. When this occurs, ;the'.vapor:pressure 'of thefuel -withinthe-working chamber will increaseand willtend to force the liquid fuel contained therein through the discharge passages210 and 212 and :ejectithesame through the nozzle element 216. If an attempt .is then made tore-start the'engine after the working chamber is evacuated, the pumping mechanism will be ineffective in providing a supply of liquid fuel to .the carburetor mixing chambers to-facilitate starting.

This same vapor-lock" condition may occur during'operation'of the-engine and will render the carburetor pumpingmechanism'ineifective to supply the carburetor barrels with a supply .of liquid fuel when the throttle is quickly openedinxan 'etfort to obtain engine acceleration.

The-presence of the-weathering well 222 is effective to considerably reduce this tendency for the-fuelto vaporize within the working chamber of the pumping mechanism as describedabove. The-fuel which is supplied to the working chamber 298 during upward movement of the piston 202:is stored in a substantially stagnant condition within the fuel weathering well 222 before it is conducted to the workingchamber through the

passages

230 and 232. While in this stagnant condition, the fuel within the weathering well may be heated by the heat of the engine to a relatively high temperature in comparison with the temperature of the fuel within the

fuel bowl portions

174 and 176. The more volatile constituents of the liquid fuel will therefore vaporize from the fuel within the weathering well before it enters the working chamber'208. Accordingly, the fuel within the working chamber 208 may be eated to a relatively high temperature before the vapor pressure increases to a value which is sufficiently high to cause the working chamber 208 to become evacuated.

If the conditions are such that the fuel within the working chamber does vaporize following a period of sustained operation in spite of the presence of the fuel weathering well, the nylon ball check valve 234 will become unseated after the working chamber 208 has become evacuated or partially evacuated under the hy drostatic pressure of the fuel exerted on the underside of valve 234. This hydrostatic pressure exists by virtue of the fact that the level of the fuel within the fuel weathering well 222 is considerably above thelevel of the lower end of the working chamber 208. The valve 234 will therefore permit the working'chamber 208 toautomatically refill following a vapor lock condition.

A further featurecf the invention resides in the novel piston construction as shown in Figure 8. The passage 248 is effective to provide communication between the working chamber 268 and the vent opening 25!) disposed above the level of the fuel in the fuel bowl. Accordingly, if the fuel within the working chamber does hecome vaporized, the vaporized gases may escape through the passage 24S and the vent 250 thus preventing a pressure buildup below the piston 202.

It is thus apparent that the weathering well, the nylon ball check valve and the vented piston rod all are designed to correct a previously existing source of operating ameulty and to provide an improved and more effective carburetor assembly. Although one preferred form of the invention has been specifically disclosed, it is contemplated that certain variations thereof may be made without departing from the scope of the following claims.

I claim:

1. In a liquid fuel carburetor for use with the intake manifold of an internal combustion engine comprising a conduit structure for accommodating the flow of combustible gases to said manifold, a throttle valve in said conduit structure for controlling said flow, a fuel bowl disposed within a portion of said carburetor adjacent said conduit structure, said fuel bowl being adapted to store a quantity of liquid fuel, nozzle means for supplying said conduit structure with fuel, first fuel passage means interconnecting said fuel bowl and said nozzle means for supplying the latter with fuel, and manually operable linkage means for actuating said valve, a carburetor pumping mechanism for discharging liquid fuel into said conduit structure, said pumping mechanism including a liquid working cylinder, a piston member slidably disposed within said cylinder and operatively connected to said linkage means, said cylinder and said piston defining a liquid working chamber, a fuel weathering well disposed in a portion of said fuel bowl out of the direct path of the fuel flow to said nozzle means and adapted to store a quantity of fuel in a substantially static condition therein, a portion of said well being recessed to provide a passageway for accommodating the transfer of fuel from said fuel bowl to said weathering well, and second fuel passage means interconnecting said weathering well and said working chamber for supplying the same with liquid fuel.

2. The combination as set forth in claim 1 wherein said second passage means includes a one-way check. valve having a movable ball valve element for permitting flow therethro-ugh into said working chamber while blocking flow therethrough from the same, said movable ball valve element being fcrmd of a non-metallic material having a specific gravity less in magnitude than two.

3. In a liquid fuel carburetor for use with the intake manifold of an internal combustion engine comprising conduit structure for accommodating the flow of combustible gases to said manifold and containing throttle valve means for controlling said flow, nozzle means opening into said conduit structure for supplying the latter with liquid fuel, a fuel bowl for storing a quantity of liquid fuel, a fuel weathering well, fuel supply means for supplying liquid feul to said bowl and well, a first fuel passage means for conducting liquid fuel from said bowl to said nozzle means, said weathering well having a fuel settling portion out of the direct path of the fuel flow between said supply means and nozzle means and adapted to store a quantity of liquid fuel in a relatively static condition, a second fuel passage means 10 for interconnecting said settling portion and conduit structure, a fuel pumping mechanism in said second fuel passage means operative to pump liquid fuel from said settling portion to said conduit structure, and linkage means operatively connected to said valve means and pumping mechanism to operate the same.

4. In a liquid fuel carburetor for use with the intake manifold of an internal combustion engine having conduit structure for accommodating the flow of combustible gases to said manifold and containing throttle valve means for controlling said flow, and also having personally operable linkage means for actuating said valve means; a fuel bowl for storing a quantity of liquid fuel, a fuel weathering well, fuel supply means for supplying liquid fuel to said bowl and well, a first fuel passage means for conducting liquid fuel from said bowl to said conduit structure, said weathering well having a fuel settling portion out of the direct path of the fuel fiow between said supply means and first fuel passage means to said conduit structure, thereby to store a quantity of liquid fuel in a relatively static condition, a fuel pumping mechanism operatively connected with said linkage to be actuated thereby, and a second fuel passage means containing said pumping mechanism and effective to conduct liquid fuel from said settling portion to said conduit structure when said pumping mechanism is actuated.

5. In a liquid fuel carburetor for use with the intake manifold of an internal combustion engine having conduit structure for accommodating the flow of combustible gases to said manifold and containing throttle valve means for controlling said flow and also having personally operable linkage means for actuating said valve means; a fuel bowl for storing a quantity of liquid fuel, a fuel weathering well, fuel supply means for supplying liquid fuel to said bowl and well, a first fuel passage means for conducting liquid fuel from said bowl to said conduit structure, said weathering well having a fuel settling portion below the base of said fuel bowl, means baffling said settling portion from the direct flow of fuel between said supply means and first passage means to said conduit structure and maintaining the fluid contents of said settling portion in a relatively static condition, a fuel pumping mechanism operatively connected with said linkage to be actuated thereby, and a second fuel passage means containing said pumping mechanism and effective to conduct liquid fuel from said settling portion to said conduit structure when said pumping mechanism is actuated.

6. The combination according to claim 5 comprising in addition check valve means blocking fluid fuel flow from said pumping mechanism into said settling portion, and wherein said settling portion is proximate said engine and subject to the heat radiated therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 2,212,926 Wirth Aug. 27, 1940 2,212,946 Mock et al Aug. 27, 1940 2,235,797 Carlson Mar. 18, 1941 2,493,804 Carlson Jan. 10, 1950 2,641,278 Eplett et al. June 9, 1953 2,709,964 Brady June 7, 1955 OTHER REFERENCES Automotive Industries, vol. 108, No. 4, February 15, 1953, page 167.