US3006616A - Multi-barrel carburetor - Google Patents

Description

1961 H. A. CARLSON ErAL 3,006,616

MULTI-BARREL CARBURETOR 5 Sheets-Sheet i Filed Jan. 5, 1959 FIG.

FIG.2.

INVENTORS HAROLD A. CARLSON OLIN J. EICKMANN ROBERT J. SMITH ATTORNEY Oct. 31, 1961 H. A. CARLSON EFAL 3,

MULTI-BARREL CARBURETOR Filed Jan. 5. 1959 5 Sheets-Sheet 2 INVENTORS HAROLD A. CARLSON OLIN J. EICKMANN ROBERT J. SMITH ZLM W ATTORNEY Oct. 31, 1961 Filed Jan. 5, 1959 H. A. CARLSON ETAL MULTI-BARREL CARBURETOR 5 Sheets-Sheet 4 HAROLD A.CARL SON OLIN J. EICKMANN BY ROBERT SMITH ATTORNEY I Oct. 31, 1961 H. A. CARLSON ETAL 3,006,616

MULTI-BARREL CARBURETOR Filed Jan. 5. 1959 5 Sheets-Sheet 5 INVENTORS HAROLD A. CARLSON OLIN J. EICKMANN ROBERT J. SMITH pgiww w ATTORNEY United States Patent 3,006,616 MULTI-BARREL CARBURETOR Harold A. Carlson, Brentwood, Olin J. Eickmann, St. Louis, and Robert J. Smith, St. Anns, Mo., assignors to ACF Industries, Incorporated, New York, N.Y., a corporation of New Jersey Filed Jan. 5, 1959, Ser. No. 784,986 8 Claims. (Cl. 261-23) The invention relates to carburetors for internal combustion engines, and more particularly to multi-stage carburetors especially for automotive engines.

It will be understood that a multi-stage carburetor comprises a primary section and a secondary section, each adapted to be supplied with fuel for admixture with air flowing therethrough to the engine on which the carburetor is used. In a typical multi-stage carburetor, the primary section comprises two primary mixture conduits or barrels, and the secondary section comprises two secondary mixture conduits or barrels, this type of carburetor accordingly being referred to as a four-barrel carburetor. The primary section is operative throughout the entire power of range of the engine. The secondary section is operable only in the upper part of the power range to supplement the primary section. Each barrel has a nozzle supplied with fuel from a fuel bowl. It is desirable .to have the discharge ends of the nozzles located as high as possible in the respective barrels to provide for more uniform and consistent flow of fuel and to avoid surging of fuel through the nozzles, as may occur, for example, when the vehicle makes a sharp turn. While it is possible to locate the discharge ends of the secondary nozzles relatively high in the secondary section, it is usually not possible to locate the discharge ends of the primary nozzles as high as the discharge ends of the secondary nozzles, because of the provision of a choke valve in the primary section. In such case, if a primary nozzle and a secondary nozzle are supplied with fuel from a bowl in which the level of fuel is the same for both nozzles, the lift (the difference in elevation of the fuel level and the nozzle discharge end) is greater for the secondary nozzle than for the primary nozzle. This results is disproportionate flow of fuel to the primary and secondary nozzles.

Accordingly, it is an object of this invention to provide a multi-stage carburetor having means providing separate reservoirs of fuel for a primary nozzle and a secondary nozzle with fuel maintained at different levels in the two reservoirs more nearly to equate the primary and secondary lifts to tend to provide more proportionate flow of fuel to the nozzles.

A further object of the invention is the provision of an economical carburetor construction for the purpose described in which only one float is used for control of fuel level in the reservoirs.

As above stated, a typical multi-stage carburetor is a four-barrel carburetor having two primary barrels and two secondary barrels. A further object of this invention is the provision of a multi-stage carburetor having a higher capacity in the upper power range than the typical fourbarrel carburetor. This is attained in a construction having six mixture conduits or barrels, of which two are pri- 1 3,006,616 Patented Oct. 31, 1961 In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

FIG. 1 is a left side elevation of a multi-barrel carburetor, in accordance with the invention.

FIG. 2 is a right side elevation of the carburetor of FIG. 1 with parts broken away and shown in section.

FIG. 3 is a plan view of the carburetor of FIG. 1 with parts broken away and shown in section.

FIGS. 4, 5, 6, 7 and 8 are cross sections taken on lines 44, 55, 66, 7-7 and 8--8, respectively, of FIG. 3.

FIG. 9 is a horizontal section taken on line 99 of FIG. 5.

FIG. 10 is an enlarged fragment of FIG. 6.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to the drawings (FIGS. 1 and 8), there is indicated at .1 in FIG. 1 an automotive vehicle having an engine 3 on which is a six-barrel carburetor 5 of this invention. Fuel is supplied to the carburetor from a fuel tank of the vehicle. A pump operated by the engine is adapted to pump fuel to the carburetor through a line 15. The carburetor 5, which has two vertical primary barrels and four vertical secondary barrels, is mounted on the intake manifold 17 of the engine, and is shown in FIG. 5 with an air filter 19 mounted thereon.

The carburetor 5, comprises a main body casting 21 which is referred to as the float bowl section, an upper section 23 which is referred to as the air horn section, and a lower section 25 which is referred to as the throttle body section. The float bowl section 21 is generally rectangular in plan, having front and back walls designated 27 and 29, and left and right side walls designated 31 and 33. It is formed to provide two fuel containers, one at each side, each of which is divided into three individual fuel bowls or reservoirs (FIG. 3). The three bowls at the left side are designated 35L, 37L and 39L. Bowl 35L is the central one of these three bowls, bowl 37L is the forward one of the three, and bowl 39L is the rearward one of the three. These bowls are defined by an inner left wall 41 extending parallel to the left side wall 31 from the front wall 27 to the back wall 29 of the float bowl section 21 and by forward and rearward crosspartitions 43L and 45L extending between walls 31 and 41. The three bowls at the right side are similar to those at the left and are designated 35R,37R and 39R. They are defined by an inner right wall 51 extending parallel to the right side wall 33 from the front wall to the back wall of the float bowl section and by forward and rearward cross- - partitions 43R and 45R (similar to partitions 43L and 45L) extending between walls 33 and 51.

The region of the float bowl section between the walls 41 and 51 is formed to provide two vertical primary mixture conduits or barrels SSL and 55R and four vertical secondary mixture conduits or barrels 57L, 57R, 59L and 59R (FIG. 3). The primary barrels SSL and 55R are located side-by-side generally centrally of the float bowl section, the barrel 55L being the left-hand primary barrel, and the barrel 55R being the right-hand primary barreL- The second- ary barrels 57L and 57R are located side-by-side forward of the primary barrels, the barrel 57L being the left-hand forward secondary barrel and the barrel 57R being the right-hand forward secondary barrel. The secondary barrels 59L and 59R are located side-by-side rearward of the primary barrels, the barrel 59L being the left-hand rearward secondary barrel, and the barrel 59R being the right-hand rearward secondary barrel. The two primary barrels SSL and 55R are identical, each being formed as indicated at 61 in FIGS. 5 and 8 toconstitute a main venturi. The four secondary barrels are identical, each being cylindrical with an enlarged upper end portion 63 providing an upwardly facing shoulder 65 (see FIG. 5). i

The six fuel bowls 35L, 37L, 39L, 35R, 37R and 39R all have the same width laterally of the carburetor, but the forward and rearward bowls 37L, 39L, 37R and 39R are shorter in front-to-rear dimension than the central bowls 35L and 35R (FIGS. 3, 4, and 8). The upper edges of the cross-partitions 43L, 45L, 43R and 45R are below the top of the float bowl section 21 and constitute weirs W over which fuel is adapted to overflow from the respective forward and rearward bowls into the respective central bowl. The left-hand forward bowl 37L is located alongside of and is adapted to supply the lefthand forward secondary barrel 57L. The left-hand central bowl 35L is located alongside ofand is adapted to supply the left-hand primary barrel 55L. The left-hand rearward bowl 39L is located alongside of and is adapted to supply the left-hand rearward secondary barrel 59L. The right-hand forward bowl 37R is located alongside of and is adapted to supply the right-hand forward sccondary barrel 57R. The right-hand central bowl 35R is located alongside of and isadapted to supply the righthand primary barrel 55R. The right-hand rearward bowl 39R is located alongside of and is adapted to supply the rearward right-hand secondary barrel 59R..

The air horn section 23 is formed to provide a roundedcorner rectangular air horn 67 through which air may enter and flow downward through the six barrels. The air horn 67 has aforward cross-partition .69 and a rearward cross-partition 71 dividing it to form a forward air inlet 73 for the two forward secondary barrels, a central air inlet 75 for the two primary barrels, and a rearward air inlet 77 for the two rearward secondary barrels. .The air horn section 213 is also formed with lateral float bowl cover portions 79L and 79R for the three left-hand bowls and the three right-hand bowls (FIG.. 3). The three bowls at each side are vented into the air horn 67 via a vent passage 81 in the air horn section and a vent tube 83 (see FIGS. 3 and 8). Each of the bowl cover portions 79L and 79R of the air horn section 21 is formed with a raised rib 85 extending from the rear thereof toward the front (FIGS. 3 and 4). Each of these ribs has .a rearward fuel inlet passage such as indicated at 87 in FIG. 4. The air horn section 2 1 is also formed with .a rearward cross-rib 89 in which is a fuel passage 91 connecting the left-hand fuel inlet passage 87 and the right-hand fuel inlet passage 87. The fuel supply line .15 is connected into the rearward end 90 of the left- -is a valve port 95 which opens downward into a bottom recess 97 in the respective bowl cover portion 79L or 79R of the air horn section 21. This recess 97 is located above the respective rearward bowl 39L or 39R,

as the case may be. Pivoted at 99 in each rearward bowl is a float arm 101. Secured to this arm is a bracket B having a portion which extends up and over the respective weir W and into the central bowl, where it carries a float 105. A needle valve member 107 is vertically slidable in a guide 109 at the lower 'end of the recess 97. This guide has openings such as indicated at 111 for flow of fuel down into the rear bowl. The lower end of the needle valve member 107 engages the bracket 103, and its 'upper end is engageable wtih the valve seat defined by the lower end of the valve port 95. Extending forward and downward from the upper end of the recess 97 in each fuel bowl cover portion 79L and 79R of the air horn section 21 is a fuel passage 113 which extends over the central bowl and opens downward at its forward 'end above the forward bowl. As to each side of the carburetor, the needle valve member 107 closes when the fuel in the central bowl 35L or 35R, as the case may be, reaches a predetermined head or level L1 below the weirsW. When the fuel level in the central bowl falls below this predetermined level L1, the valve member opens. Fuel then flows down through the valve port 95 and the recess 97 into the rearward bowl. Fuel also flows through the passage 113 to the forward bowl. The flow of fuel continues until the forward and rearward bowls fill up, and then fuel flows over the weirs W into the central bowl to bring up the fuel level in the latter to the level L1. Thereupon the needle valve member 107 closes to cut off the flow. Thus, a higher fuel level L2 is maintained in the forward and rearward bowls than in the central bowl. The fuel level L2 in the forward and rearward bowls corresponds to the height of the weirs W, the float being adjusted so that fuel level L1 in the central bowl is below the level of the weirs.

The throttle body section 25 is provided with two primary throttle bores such as indicated at 115 which register with the lower ends of the primary barrels SSL and 55R (FIGS. 5 and 8). The throttle body section 25 is also provided with two forward secondary throttle bores such as indicated at 117 which register with the lower ends of the two forward secondary barrels 57L and 57R, and with two rearward secondary throttle bores such as indicated at 119 which register with the two rearward secondary barrels 59L and 59R. Journalled in the throttle body section 25 and extending laterally across the two primary throttle bores 115 is a primary throttle shaft 121. This primary throttle shaft carries 'a primary throttle valve 123 in the left-hand primary throttle bore, and a similar primary throttle valve 123 in the right-hand primary throttle bore. Fixed 'on the left-hand end of the primary throttle shaft 121 are inner and outer primary throttle arms 125 and 127 (see FIG. 1). Journalled in the throttle body section 25 and extending laterally across the two forward secondary throttle bores 117 is a forward secondary throttle shaft 129. This carries a secondary throttle valve 131 in the left-hand forward secondary throttle bore 117 and a similar secondary throttle valve 131 in the righthand forward secondary throttle bore. Iournalled in the throttle body section 25 and extending laterally across the two rearward secondary throttle bores 119 is a rearward secondary throttle shaft 133. This carries a secondary throttle valve 135 in the left-hand rearward secondary throttle bore, and a similar secondary throttle valve'135 in the right-hand rearward secondary throttle bore.

The left-hand central bowl 35L is the source of fuel for a left-hand primary high speed system and a lefthand low speed system for supplying fuel to the left-hand primary barrel 55L. The right-hand central bowl 35R is the source of fuel for a right-hand primary high speed system and a right-hand low speed system for supplying fuel to the right-hand primary barrel 55R. The leftand right-hand primary highspeed systems are identical, and a description of the left-hand primary high speed system will suflice for both. As shown in FIG. 6, the float bowl section 21 is formed with a well 137 extending down from its top in the wall 41 adjacent the rear of the central bowl 35L. A slot 139 (see FIG. 4) is provided in Wall 41 for communication between the central bowl'35L and the upper portion of the well. This slot 139 extends down below fuel level L1 for flow of fuel from the central bowl into the well. Toward the bottom of the well is a primary metering jet 141 (see FIG. 6). Below this jet there is a horizontal passage 143 to a vertical recess 145 in the wall 41 extending up from the bottom of the float .bowl section 21 between the central bowl 35L and the primary barrel 55L. This recess 145 is closed at the bot torn by the throttle body section 25 (FIG. 8) Flow of fuel through the metering jet 141 to the recess 145 is under control of a step-up rod 147 which extends down from a pocket 149 in the air horn section 23 through a hole 151 in the air horn section. At its upper end, the step-up rod is bent to have a horizontally extending arm 153 which is received in a piston 155. This piston is slidable in a vertical cylinder 157 provided in the air horn section and is biased upward by a spring 159. There is an opening 161 at the lower end of the cylinder 157 which registers with the upper end of a vacuum passage 163 in the float bowl section 21. The lower end of the vacuum passage 163 registers with the upper end of a vacuum passage 165 in the throttle body section 25. The vacuum passage 165 has a horizontal portion 167 opening into the throttle bore 115 in the throttle body section below the primary throttle valve 123. The lower end of the step-up rod 147 is formed so that, upon increase of vacuum below the piston 155, with resultant downward movement of the piston and the rod, the flow of fuel through the jet 141 is restricted, and vice versa. A cover cap for the pocket 149 is indicated at 169.

At the upper end of each primary barrel is a primary venturi 171 on a primary venturi arm 173 (FIGS. and 8). This arm 173 extends into the barrel from the side thereof toward the respective central bowl. The arm has a passage 175 in which is pressed a fuel nozzle 177. This nozzle projects into the primary venturi 171. The passage 175 extends from an opening 179 above the recess 145. A perforated main fuel tube 181 extends down from the opening 179 into the recess 145. During high speed operation (i.e., with the primary throttles 123 open), fuel flows from the left-hand central bowl 35L to the left-hand primary barrel 55L via slot 139, well 137, jet 141, and passage 143 to recess 145, thence through the main fuel tube 181 and out through nozzle 177 into the primary venturi'171. The high speed system for supplying fuel from the right-hand central bowl 35R to the right-hand primary barrel 55R is identical.

The leftand right-hand low speed systems are identical, and a description of the right-hand low speed system will sufiice for both. As shown in FIG. 8, an idle tube 183 extends down in the recess 145 from a hole 185 which extends down from the top of the float bowl section 21. The upper end of this hole 185 registers with a vertical hole 187 in the air horn section 23. From this vertical hole 187 there is a horizontal passage 189 (see FIGS. 3 and 8) in the air horn section to a vertical hole 191 (see FIGS. 3 and 5) which extends up from the bottom of the air horn section. This latter hole 191 registers with a vertical hole 193 extending through the float bowl section. Hole 193 opens at its lower end into a recess 195 (FIGS. 5 and 9) in the throttle body section 25, from which there is an idle discharge port 197 opening into the primary throttle bore 115. An idle adjusting screw 199 (see FIG. 9) is threaded in a horizontal hole 201 which leads into the recess 195 below the idle discharge port 197. An idle needle port 203 leads into the primary throttle bore 115 from the hole 201. An air bleed hole 205 (see FIG. 5) leads into the upper end of the vertical hole 191.

An accelerating pump indicated at 207 is provided for discharging fuel into the primary barrels at their upper ends during acceleration from low speeds. As appears in FIGS. 3, 6 and 10, this pump comprises a plunger rod 209 operable in a vertical cylinder 211 formed in the Wall 41 adjacent the rearward end of the left-hand forward bowl 37L. This cylinder 211 extends down from the top of the float bowl section 21 and is covered by the air horn section 23. The rod 209 extends down into the pump cylinder 211 from the air horn section 23 through a hole 213 in the bottom of the latter. The rod 209 has spaced heads 215 and 217 at its lower end, head 215 being the upper one of the heads and head 217 being the lower.

The rod has a packing member generally designated 219 retained thereon by the heads 215 and 217. This packing member is made of a flexible resilient elastomeric material in the form of an inverted cup, having a substantially flat circular top wall 221 and an annular skirt portion 223 of downwardly flaring conical form. The top wall 221 is provided with a central hole which may be a square hole, the portion of the rod between the heads (which may be cylindrical) being freely slidably received (FIGS. 2, 3, 6, and 7).

in this hole. The packing member is preferably formed from sheet material composed of polymerized tetrafluoroethylene such as is sold under the trade designation Teflon, having a thickness less than the spacing of the heads 215 and 217. The packing member is mounted on the portion of the rod between the heads with its annular skirt portion 223 extending downward surrounding the lower head 217. The dimensions of the packing member are initially such that the skirt as received in the cylinder is radially compressed so as to have a sliding sealing fit in the cylinder 211.

The top wall 221 of the packing member 219 is provided with holes such as indicated at 225, these holes being located radially outward from the center hole. The top wall 221 of the packing member is slidab le on the rod between the relatively lowered position in which it is shown in FIG. 10 in flatwise engagement with the lower head 217 and a relatively raised position in flatwise engagement with the upper head 215. In the raised position, holes 225 are closed by the upper head 215. The lower head 217 is provided with an annular series of holes such as indicated at 227 (which may be arcuate slots) with which the holes 225 register when the top wall 221 of the packing member is in the lowered position. The rod 209 has an axial passage 229 extending up from its lower end and transverse holes such as indicated at 231 traversing the portion thereof between the heads 215 and 217 and intersecting passage 229 providing lateral ports opening from passage 231 to the space between the heads 215 and 217.

The rod 209 is biased downward by a coil compression spring 233 reacting from the bottom of the air horn section 23 against the upper head 215. The rod 209 is linked to the primary throttle shaft 121 to be pulled up against the bias of the spring 233 when the primary throttle valves 123 are closed by means of a linkage such as shown in FIG. 1 i'ndluding a link 235 connecting the outer primary throttle arm 127 to a pump rocker 237 pivoted at 239 on the air horn section 23, and a ling 239a connecting rocker 237 to the upper end of the rod 209. Fuel is supplied to the pump cylinder 211 above the packing member 219 from the left-hand forward bowl 37L via a passage 240 (see FIG. 4). Fuel is discharged from the pump cylinder on downward movement of the rod 209 through a discharge passage 241 (FIGS. 3 and 6) leading from the lower end of the cylinder to a pump jet cluster 243 located forward of and between the two primary barrels SSL and 55R and including two jets 245 for discharging pumped fuel into the two primary barrels. When the rod 209 is driven downward upon opening of the primary throttle valves, the packing member 219 occupies the raised position in which its top wall 221 engages the upper head 215 and holes 225 are closed. When the rod 209 moves upward on closing the primary throttle valves, the packing member slides down relative to the rod to its lowered position in which holes 225 are opened for flow of fuel from above the packing member to below the packing member to prime the pump. A 'disch-arge check valve may be incorporated in passage 241.

Journalled in the air horn section 23 and extending laterally across the central air inlet 75 for the two primary barrels SSL and 55R is a choke valve shaft 247 This carries a choke valve 249 for both primary barrels. There are no choke valves for the secondary barrels. Secured on the right end of the choke shaft 247 is an am 251 (see FIG. 2). Mounted on the right side of the float bowl section 21 is an automatic choke control housing 253. This contains thermostatic coil 255 controlling a lever 257 on a shaft 259. At 261 is indicated at choke piston slidable in a choke cylinder 263. Link 265 connects the choke piston 261 and lever 257. The vacuum port for choke cylinder 263 is indicated at 267. The hot air inlet for the housing is indicated at 269 and is connected to a heat pocket or stove 7 on the exhaust manifold of the engine 3. A link 274 conmeets a lever 577 fired to shaft 259'to arm 251.

At the upper end of each secondary barrel 57L, 57R, 59L and 59R is'a secondary venturi cluster designated in its entirety by the reference character 275 (FIGS. 3 and This includes a ring 277 which seats on the shoulder 65 and which is formed to provide a main venturi, and an upwardly angled arm 279 extending toward the center of the ring and carrying a boost venturi 281. In view of the upward angling of the arms 279, the boost venturis are located at a higher elevation than the primary venturis 171 in the primary barrels SSL and 55R. This will be apparent from FIGS. 5 and 7. Each cluster 275 includes a block 283 seated in a recess 2S5 therefor in the float bowl section 21 (FIGS. 3, 6 and 7). For each secondary barrel there is a secondary'fuel system including a vertical hole 287 (FIG. 6) in the float bowl section 21 extending up to the bottom of'the block 283. Hole 287 is closed at the bottom by the throttle body section The block 283 has a vertical hole 289 of smaller diameter than'hole 287 extending up from its bottom. A fuel tube 291 extends down from hole 289 into the hole 287. Each cluster has a hole 293 extending through its arm 279 to the hole 289, with a fuel nozzle 2'95 pressed in the hole 293 and'projecting into the boost venturl 281. The upper discharge ends of these secondary nozzles 295 are higher than the discharge ends of the primary nozzles 177 (FIG. 5). As to each secondary barrel, fuel is supplied to the lower end of the respectivehole 287 from the respective secondary supply bowl (37L, 37R, 39L, 39R, as the case may be) through a secondary system passage 297 (FIGS. 3 and 6). In the hole 287 above this passage 297 is a metering jet 299.

Iourn-alled in the float bowl section 21 and extending laterally across the two forward secondary barrels 57L and 57R is a forward velocity valve shaft 301 (FIGS. 3, 5 and 7). This carries a velocity valve 303 in the left-hand forward secondary barrel 57L and a similar velocity valve 303 in the right-hand forward secondary barrel 57R. Journalled in the float bowl section '21 and extending laterally across the two rearward secondary barrels 59L and 59R is a rearward velocity valve shaft 305. This carries a velocity valve 307 in the lefthand rearward secondary barrel 59L and a similar velocity valve 307 in the right-hand rearward secondary barrel 59R. The forward velocity valve shaft 301 is biased to rotate in valve-closing direction by a clock spring 309 located in a pocket 311 in the float bowl section 21 between the forward secondary barrels. The rearward velocity valve shaft 305 is biased to rotate in valve closing direction by a similar clock spring 313 located in a similar pocket 315 in the float bowl section between the rearward secondary barrels.

Referring to FIGS. 1 and 3, the outer primary throttle arm 127 is shown to carry a fast idle adjusting screw 317 engageable with a fast idle cam 319 pivoted at 321 on the left side Wall 31 of the float bowlsection 21. The choke shaft 247 has an arm 323 fixed on its left 'end. A link 325 connects arm 323 to a lever 327 pivoted at 321 along with cam 319.. Lever 327 has a lateral lug 329 engageable by the cam. A coil spring 331 biases the cam to rotate clockwise toward engagement with this lug. As the choke valve opens, arm 323 swings counterclockwise as viewed in FIG. 1, the lever 327 is rotated clockwise to let off the cam 319, which follows lever 327 around. The lever 327 has a second lug 333 which extends through a notch 335 in the cam under one end of the spring 331. A secondary lockout lever 337 is also pivoted at 321 on the left side wall of the float bowl section 21. This is. gravity-biased toward latching engagement with a lug 339 on the rearward secondary throttle shaft 133, and is engageable by the -lug 329 to be swung out of latching engagement with lug 339 when the lever 327 is swung clockwise on open- :ing of. the choke valve. When the primary throttle valves are fully opened, a lug 341 on the end of the inner throttle arm 125 engages cam 319 to rotate the cam and the lever 327 clockwise, thereby partially to open the choke valve for unloading purposes. An idle speed screw 343 is threaded in a lug 345 on the left side wall 31 of the float bowl section 21. This is engageable by a lug 347 on the inner primary throttle arm 125.

Referring to FIGS. 2 and 3, the primary throttle shaft 121 is shown to have an inner arm 349, a dog 351 and an outer arm 353 at its right end. The inner arm 349 and the dog 351 are rotatable relative to the shaft 121 and to one another. The outer arm 353 is fixed to the shaft .121. The dog has a first lateral lug 355 engageable with the outer arm 353 and a second lateral lug 359 engageable with the inner arm 349. A coil spring 361 biases the dog to rotate in the direction for engagement of its lug 355 with the outer arm 353. A link 363 connects the inner arm 349 and an arm 365 fixed on the right end of the rearward secondary throttle shaft 133. A coil spring 367 is provided for biasing the rearward secondarythrottle valves 135 closed. A link 369 connects arm 365 to an arm 371 fixed on the right end of the forward secondary throttle shaft 129, so that the latter operates in unison with the rearward secondary throttle shaft 133. When the primary throttle valves 123 are opened, the outer arm 353 rotates counterclockwise as viewed in FIG. 2 along with the primary throttle shaft 121. Dog 351 (having lugs 357 and 359) thereon follows the arm 353 around under the bias of spring 361. When the primary throttle valves have been opened a predetermined amount (50, for example), lug 359 comes into engagementwith the inner arm 349 and rotates it counterclockwise. This results in opening of the forward and rearward secondary throttle valves 131 and 135. The secondary throttle linkage is so proportioned that the secondary throttle valves operate in unison and in phase and arrive at their wide open position at the same time as the primary throttle valves. A shoe 373 on arm 365 is engageable with a shoe 375 on arm 353 to preclude opening of the secondary throttle valves until the primary throttle valves have been opened approximately the stated predetermined amount.

Operation is as follows:

The four secondary bowls 37L, 37R, 39L and 39R hold fuel up to the level L2 of the weirs W, but the two primary bowls 35L and 35R hold fuel only up to the level L1 below the level L2 as determined by the float 105. Thus, while the discharge ends of the four secondary nozzles 295 at a higher elevation than the discharge ends of the primary nozzles 177, by appropriate positioning of the float 105 relative to the float arm 101,

'the lifts for the primary nozzles and the secondary nozthan the lift for the primary nozzles, and the flow to the (which may be referred to as primary bowls) through primary nozzles would accordingly be disproportionately greater than the flow to the secondary nozzles.

The primary throttle shaft 121 is operated by the vehicle pedal, connection being made to the inner primary throttle am 125 below the shaft 121. The primary throttle shaft 121 is biased in primary throttle valve closing direction (which is counterclockwise as viewed in FIGS. 1 and 5) by the pedal return spring. When the pedal isdepressed, the primary arms 125 and 127 and the primary throttle shaft 121 are rotated clockwise as viewed in FIG. 1 to open the primary throttle valves 123. When the primary throttle valves are partly opened,

fuel is drawn from the central bowls 35L and 35R 9 the primary discharge nozzles 177 and mixed with air flowing through the primary barrels SSL and 55R. zAS

the level of fuel in the primary bowls 35L and 35R goes down, the needle valves 107 associated with these bowls open up, and fuel is thereby supplied to the forward and rearward bowls 37L, 39L, 37R and 39R (which may be referred to as secondary bowls). These secondary bowls already being full, fuel immediately overflows therefrom and brings the fuel level in the primary bowls back up to the level L1. At this point, the floats 105 close the needle valves 107 to cut off further flow of fuel to the secondary bowls.

When the primary throttle valves 123 are opened to the point where the secondary throttle valves 303 and 307 are opened, fuel is drawn from the secondary bowls 37L, 39L, 37R and 39R as well as from the primary bowls 35L and 35R. As the level of fuel goes down in the primary bowls, the needle valves 107 open as above described, and fuel is supplied to the secondary bowls. 'Ihese fill up, and then overflow into the primary bowls, thereby bringing the fuel in the latter back up to the level L1.

Opening of the forward and rearward secondary throttle valves 303 and 307 is accomplished by means of the link 363 connecting the inner arm 349 on the primary throttle shaft 121 at the right side of the carburetor to the arm 365 on the rearward secondary throttle shaft 133, and by the link 369 connecting the arm 365 to the arm 371 on the right-hand end of the forward secondary throttle shaft 129. Thus, the forward and rearward secondary throttle valves are operated in unison and in phase.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. In a carburetor having a first mixture conduit and a. second mixture conduit, vertically spaced first and second venturis in their respective conduits, nozzles to discharge fuel into their respective venturis, a first reservoir for containing fuel to be supplied to the first conduit, a second reservoir for containing fuel to be supplied to the second conduit, said second reservoir having a fuel inlet adapted to be connected to a source of fuel, and a fuel outlet to supply fuel by gravity into the first reservoir when the head of fuel in the second reservoir increases above a predetermined level, and means includiug a valve in said inlet for controlling the flow of fuel from said source into said second reservoir to cut off flow of fuel from said source when the fuel in the first reservoir reaches a predetermined level below the level of fuel in the second resrvoir.

2. In a carburetor having a first mixture conduit and a second mixture conduit, vertically spaced first and second venturis in their respective conduits, nozzles to discharge fuel into their respective venturis, a first reservoir for containing fuel to be supplied to the first conduit, 21 second reservoir for containing fuel to be supplied to the second conduit, said second reservoir having a fuel inlet adapted to be connected to a source of fuel, and a fuel outlet to supply fuel by gravity into the first reservoir when the head of fuel in the second reservoir increases above a predetermined level, and means including a valve in said inlet for controlling the flow of fuel from said source into said second reservoir to cut off flow of fuel from said source when the fuel in the first reservoir reaches a predetermined level below the level of fuel in the second reservoir, and a float in said first reservoir to actuate said valve.

3. In a carburetor having a first mixture conduit and a second mixture conduit, vertically spaced first and second venturis in their respective conduits, nozzles to discharge fuel into their respective venturis, a first reservoir for containing fuel to be supplied to the first conduit, a second reservoir for containing fuel to be supplied to the second conduit, said second reservoir having a fuel inlet adapted to be connected to a source of fuel, and a fuel outlet to supply fuel by gravity into the first reservoir when the head of fuel in the second reservoir increases above a predetermined level, and means including a valve in said inlet for controlling the flow of fuel from said source into said second reservoir to cut off flow of fuel from said source when the fuel in the first reservoir reaches a predetermined level below the level of fuel in the second reservoir, and a float in said first reservoir to actuate said valve, said fuel outlet comprising a partition over which excess fuel flows from the second reservoir to said first reservoir.

4. In a carburetor having a vertical primary mixture conduit and a vertical secondary mixture conduit, a primary fuel system for supplying fuel to the primary conduit at one elevation in said primary conduit, a secondary fuel system for supplying fuel to the secondary conduit at a higher elevation in said secondary conduit, a primary bowl for containing fuel for the primary system, a secondary bowl for containing fuel for the secondary system, a partition providing a weir between said bowls, said secondary bowl being adapted to be supplied with fuel from a source thereof, excess fuel supplied to said secondary bowl being adapted to overflow therefrom into the primary bowl when it reaches a predetermined overflow level in said secondary bowl, and valve means for controlling the flow of fuel from said source to said secondary bowl and adapted to cut off flow of fuel from said source when the fuel in the primary bowl reaches a predetermined level lower than said overflow level.

5. In a carburetor having a vertical primary mixture conduit and a vertical secondary mixture conduit, a primary fuel system for supplying fuel to the primary conduit at one elevation in said primary conduit, a secondary fuel system for supplying fuel to the secondary conduit at a higher elevation in said secondary conduit, a primary bowl for containing fuel for the primary system, a secondary bowl for containing fuel for the secondary bowl being adapted to be supplied with fuel from a source thereof, excess fuel supplied to said secondary bowl being adapted to overflow therefrom into the primary bowl when it reaches a predetermined overflow level in said secondary bowl, and valve means for controlling the flow of fuel from said source to said secondary bowl and adapted to cut off flow of fuel from said source when the fuel in the primary bowl reaches a predetermined level lower than said overflow level, and a float in said primary bowl to actuate said valve means responsive to the level of fuel in the primary bowl.

6. In a carburetor having first, second and third mixture conduits, a venturi in each conduit, the venturis in said second and third conduits being in a common horizontal plane above the venturi in the first conduit, nozzles to discharge fuel into their respective venturis, a first reservoir for containing fuel to be supplied to the first conduit, 3. second reservoir for containing fuel to be supplied to the second conduit, a third reservoir for containing fuel to be supplied to the third conduit, said second and third reservoirs being adapted to be supplied with fuel from a source thereof and having overflow weirs adapted to supply excess fuel by gravity to the first reservoir, and a valve controlling the flow of fuel from said source and adapted to cut off flow of fuel from said source when the head of fuel in the first reservoir reaches a predetermined level below the fuel level in said second and third reservoirs.

7. In a carburetor having first, second and third mixture conduits, a venturi in each conduit, the venturis in said second and third conduits being in a common horizontal plane above the venturi in the first conduit, nozzles to discharge fuel into their respective venturis, a first reservoir for containing fuel to be supplied to the first conduit, a second reservoir for containing fuel to be supplied to the second conduit, a third reservoir for containing fuel to be supplied to the third conduit, said second and third reservoirs being adapted to be supplied with fuel from a source thereof and having overflow weirs adapted to supply excess fuel by gravity to the first reservoir, and a valve controlling the flow of fuel from said source and adapted to cut off flow of fuel from said source when the head of fuel in the first reservoir reaches a predetermined level below the fuel level in said second and third reservoirs, said valve being actuated by a float in the first reservoir.

8. A carburetor having a vertical primary mixture and first and second vertical secondary mixture conduits arranged in a row with the primary conduit between the secondary conduits, a venturi in each conduit, a fuel nozzle in each venturi, the venturi in the primary conduit being spaced below the other venturis, a fuel container extending alongside said conduits and divided into a primary bowl and first and second secondary bowls by first and second partitions, said primary bowl being located between the secondary bowls alongside theprimary conduit, said first and secondsecondary bowls being located alongside the first and second secondary conduits, said carburetor having a fuel inlet adapted to be supplied with fuel from a source and passages from said inlet for simultaneously supplying fuel to said secondary bowls, excess fuel supplied to said secondary bowls being adapted to overflow therefrom over said partitions when it reaches the top of said partitions, and float-controlled valvemeans including a float in said primary bowl for controlling flow of fuel from said inlet through said passages to said secondary bowls and adapted to cut 01f flow through said inlet when'the fuel in the primary bowl reaches a predetermined level below the top of said partitions.

References Cited in the file of this patent UNITED STATES PATENTS 1,323,786 Richard Dec. 2, 1919 1,449,664 Friz Marg27, 1923 1,586,097 McCarthy et al May 25, 1926 2,420,925 Wirth May 20, 1947

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