US3208738A

US3208738A - Carburetor

Info

Publication number: US3208738A
Application number: US139546A
Authority: US
Inventors: Johnson Dolores
Original assignee: ACF Industries Inc
Current assignee: ACF Industries Inc
Priority date: 1960-01-15
Filing date: 1961-09-20
Publication date: 1965-09-28
Anticipated expiration: 1982-09-28

Description

Sept. 28, 1965 E. A. JOHNSON 3,208,738

I GARBURETOR 5 Sheets-Sheet 1 Filed Sept. 20. 1961 379 INVENTOR.

ELDON A.JOHNSON AGENT Sept- 23, 1965 E. A. JOHNSON 3,208,738

CARBURETOR Filed Sept. 20, 1961 5 Sheets-Sheet s IN V EN TOR.

ELDON A.JOHNSON 6/ am'r m- 28, 1 E. A. JOH-NSON 3,208,738

CARBURETOR Filed Sept. 20 1961 Q 5 Sheets-Sheet 5 INVENTOR. ELDON A. JOHNSON AGENT Patented Sept. 28, 1965 3,208,738 CARBURETOR Eldon A. Johnson, Sunset Hills, M Dolores Johnson, admlnistratrix of said Eldon A. Johnson, deceased, us siguor to ACE Industries, Incorporated, New York, N.Y., a corporation of New Jersey @riginal application Jan. 15, 1960, Ser. No. 2,660. Di-

vided and this application Sept. 20, 1961, Ser. No.

12 Claims. '(Cl. 261-43) a constant circulation of fuel from the tank to the carburetor and back to the tank when the engine is in operation. This type of fuel system may be referred to as a recirculating" system, since'fuel is constantly being recirculated through the system when the engine is in operation. In such a system, fuel needs to be pumped from the tank to' the fuel bowl at a rate inexcess of the engine fuel demand in order to maintain the predetermined level or head of fuel-in the-bowl for accurate metering of fuel from the bowl to the engine, and overflow fuel needs to be pumped back to the tank. The pumping of overflow fuel back to the tank is referred to as scavenging.

Basically, the object of the invention is the provision of a practical, economical,recirculating system adapted reliably to supply the engine fuel demand which, as will be readily understood, varies widely with variations in the load on the engine, the system beingsuch as to avoid vapor lock difficulties and flooding. To accomplish this basic object, the invention includes a novel overflow carburetor.

Among the objects of this invention to the carburetor may be noted the provision of an overflow carburetor construction which tends to avoid vapor lock and which is such as to minimize the effect of sudden acceleration and deceleration of the vehicle and cornering-ofthe vehicle on the level of fuel in the fuel bowl of the carburetor, and which is adapted accurately to meter fuel to the engine in accordance with all the various engine fuel demands that. may occur, as during idling of the engine, during light load and heavy load operation, and during acceleration; and the provision of an overflow carburetor construction which is compact for its capacity and which maybe of relatively low height.

Cther objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the-constructions hereinafter described, the scope of theinvention being indicated in the following claims.

In the accompanying drawings, in which several of various possible embodiments of the invention are illustrated,

FIG. 1 is a plan of the carburetor per se;

FIG. 2 is an end elevation of the carburetor (which is its front end as mounted on the engine);

FIG. 3 is a side elevation of the carburetor (its left side as mounted on the engine);

FIG. 4 is a view essentially in horizontalsection on line 4-4 of FIG. 2, and with parts additionally broken away and shown in section, showing the main body of the carburetor as it appears with the air hornsection of the carburetor removed;

FIG. 5 isa vertical longitudinal section taken on line 5-5 of FIG. 1;

FIG. 6 is a vertical section taken essentially on :line 6--6 of FIG. 4;

FIG. 7 is an idealized section illustrating'an idle system of the carburetor;

FIG. 8 is a vertical transverse section taken on line 88 of FIG. 1;

FIG. 9 is an enlarged fragment of FIG. 5;

FIG. 10 is a bottom plan view of the air horn section per se of the carburetor;

FIG. 11 is a vertical section taken on line 11-11 of FIG. 4;

FIG. 12 is a perspective of a bar and metering pin assembly used in the carburetor; and

FIG. 13 is a view in elevation illustrating a' recirculat-v ing fuel system incorporating the carburetor of this invention mounted on the engine of an automotive vehicle.

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

Referring to FIG. 13 of the drawings, there is indicated at 1 the frame of an automotive vehicle having engine 3 at the front. The engine is adapted to be supplied with fuel from fuel tank 5 at the rear of the vehicle by a recirculating fuel system S of this invention which includes pump P and the novel carburetor C of this invention mounted on the engine. Pump P is mounted on the side of the engine. Carburetor C is mounted on intake manifold 7 on top of the engine. An air filter for carburetor C is indicated at 9. The exhaust manifold of the engine is indicated at.11.

- Carburetor C is a floatless carburetor, having a fuel bowl B and an overflow chamber 0 (see FIG. 4). "Fuel spills over into the overflow chamber from the bowl on exceeding a predetermined level in the bowl, as will be made clear. Pump P is a dual diaphragm pump comprising a primary pump section having an inlet nipple to which is connectde a fuel supply line 21 from fuel tank 5 and an outlet nipple to which is'connected a fuel delivery line 25 leading to the fuel bowl B of carburetor C. It also comprises ascavenger pump section having an inlet nipple to which is connected a fuel line 31 from the overflow chamber 0 of the carburetor C and an outlet nipple to which is connected a fuel return line 35 leading back to the tank 5. An electric pump 37 may be provided in tank 5 for pumping fuel from the tank through line 21 to the primary pump section 17. This is optional.

Referring to FIGS. 1-8, carburetor C is shown to be a dual downdraft carburetor, comprising a main body 201 constituted by a casting formed to provide a forward fuel bowl section 203 and a rearward mixture conduit section 205, the terms forward and rearward relating to the position of the carburetor as. mounted on the engine 3. Secured on top of the body'201 is a casting 207 which is referred to as the air horn section of the carburetor. Secured to the bottom of the mixture conduit section 205 of the body 201 is a casting 209 which is referred to as the throttle body section of the carburetor.

The rearward mixture conduit section 205 of the body 201 is formed to provide two .vertical mixture conduits or barrels 211 located side-by-side. Each of the two mixture conduits is of venturi form, and both'mixture conduits extend down from'an upper recess 213 in the top of the body201 to the bottom of the body 201. The air horn section 207 has an air inlet 215 registering with recess 213 for admission of air tothe two mixture conduits, and a rim 217 for attachment of an air filter for filtering air supplied to the mixture conduits. Throttle body 209 is formed with two throttle bores 219 registering with the lower ends of the respective mixture conduits 211. A throttle shaft 221 is journaled in the throttle 209, extending transversely across the bores 2R9 and carrying two throttle valves 223, one in each bore. A choke shaft 225 is journaled in the air horn section 207 extending transversely across the air inlet 215 and carrying a choke valve 227. The choke valve 227 is unbalanced to open and, when fully open, extends substantially vertically. When vertical, its lower portion is accommodated in the recess 213 at the top of the main body 201.

The fuel bowl section 203 of the main body 201 is essentially hollow, being formed to provide a substantially U-shaped-fuel bowl B including an overflow chamber 0, with the fuel bowl enclosing the overflow chamber. The fuel bowl is separated from the overflow chamber by a. ti-shaped wall or partition 229 (see FIGS. 4, 5 and 8) extending up from the bottom of the hollowed-out fuel bowl section of the main body, this wall 229 being spaced inward from the outer wall 231 of the fuel bowl section. The main body 201 has a transverse wall 233 dividing the fuel bowl section 203 from the mixture conduit section 205. This wall 233 has a central forward offset 235 and a central rearward offset 237 of generally triangular shape in plane (see FIG. 4). Triangular offset 237 has a flat horizontal upper surface 239 below the top of the main body 201 constituting a shoulder on which is secured a venturicluster generally designated 241. This cluster comprises a body 243 secured on shoulder 239 and two arms each designated 245 radiating from the body 243 over the two mixture conduits, each arm having a primary venturi 247 at its outer end generally coaxial with the respective mixture conduit. Each arm 245 has a fuel passage 249 opening into the respective primary venturi via a fuel nozzle 251 pressed into the outer end of the passage 249. Triangular oflset 237 is formed with two fuel wells each designated 253 extending down from the top thereof on opposite sides of the longitudinal center line of the carburetor. A main fuel tube 255 extends down into one of these wells from the inner end of one fuel passage 249, and an identical main'fuel tube 255 extends down into the other of these wells from the inner end of the other fuel passage 249.

The fuel bowl section 203 of the main body 201 of the carburetor C is integrally formed with a reentrant wall portion forming a cylinder block 257-(FIGS. 4 and 5) extending forward from the central forward offset 235 of the dividing wall 233 approximately to the center of the fuel bowl section 203. The rearward portion of this block constitutes a vertical step-upcylinder 259 (FIGS. 4 and 7) and the forward portion of this block constitutes a vertical accelerating pump cylinder 261. Bore 263 of "the step-up cylinder 259 extends down from the top of the rearward portion of the block. Bore 265 of the pump cylinder extends down from the top of the forward portion of the block (which is of lower height than the rearward portion). The wall or partition 229 which separates the fuel bowl B and the overflow chamber surro nds the pump cylinder 261 and has weir portions .267 (FIGS. 4 and 8) extending laterally between it and block 257 in a vertical transverse plane intermediate the step-up and pump cylinders 259 and 261 (FIGS. 4 and 8). Wall 229 extends around the pump cylinder 261 from the outer end of one weir portion to the outer end of the other weir portion. The arcuate portion of wall 229 extends up to the top of the fuel bowl section, as indicated in FIG. 8. Weir portions 267 have bevelled upper edges-271 (see FIGS. 8 and 11) below the top of the fuel bowl section. Extending forward from the bottom of overflow chamber 0 in main body 201 is an outlet passage or drain 273 (see FIG.

Thus, fuel bowl B has two lateral rearward chambers each designated 275 on opposite sides of the step-up cylinder 259 which are interconnected by the forward U-shaped chamber 277 extending around the overflow chamber 0. The overflow chamber 0 is also of U-shape, extending around the accelerating pump cylinder 261.

Fuel in the fuel chamber B will flow over the weirs 267 from the rearward fuel bowl chambers 275 into the overflow chamber 0 when the level of fuel in the fuel chamber B exceeds the level of the sharp upper edges 271 of the weirs.

The overflow fuel is adapted to drain out of the overflow chamber through the outlet passage or drain 273. Thus, by maintaining delivery of fuel to the fuel bowl, when the engine is in operation, at a rate faster than the rate at which fuel is consumed by the engine, fuel may be maintained in the fuel chamber B and-more particularly in the rearward lateral chambers 275 at a substantially constant level corresponding to the level of the upper edges 271 of the weirs. This maintains a substantially constant head of fuel in the fuel bowl chambers 275 for accurate high-speed metering of fuel by the jets 279 and step-up rods 281 to the engine in accordance with engine requirements.

The air horn section 207 has a forward portion 283 (FIG. 6) which constitutes a cover for the fuel bowl section 203 of the main body 201. At the forward end of the air horn section is an upwardly extending central boss 285. Extending upward from the bottom of the air horn section into this boss is a vertical cylindrical hole 287 which is countersunk at its open lower end as indicated at 289. A hole 291 is drilled at an angle in the boss to an intersection with the upper end of the vertical hole 287.

Holes

291 and 287 constitute the fuel inlet for the fuel bowl B, a fuel inlet nipple 293 being pressed in the outer end of the angled hole 291, the vertical hole 287 being located above the forward end portion of the U- shaped forward fuel bowl chamber 277. The rate of flow of fuel into the fuel bowl B is adapted to be controlled by a metering pin 295 having a tapered upper end movable up and down'in the vertical hole 287 by means to be described. Acordingly, fuel entering the fuel bowl B through hole 289 divides and flows around through the two sides of the U-shaped fuel bowl chamber 277 to the rearward fuel bowl chambers 275. Sediment in fuel in the U-shaped fuel bowl chamber 277 tends to settle to the bottom thereof, where it is trapped from being carried into the rearward fuel bowl chambers 275 by baflles 297 (FIG. 4) extending across the U-shaped fuel bowl chamber from the outer fuel bowl wall 231 to the inner wall 269. Overflow chamber 0 also has sediment baffles 299 extending between the inner wall 269 and the accelerating pump cylinder 261. Fuel flowing over weirs 267 flows forward in two sides of theU-shaped overflow chamber 0 over these baflles 299 to the forward end of the overflow chamber, and thence out through drain 273. The latter has an outlet nipple 301 pressed in its outer end (FIG. 6).

The air section 207 is integrally formed with bosses 303 and 305 (see FIGS. 8 and 10) on its bottom which substantially fill the space in the U-shaped fuel bowl chamber 277 above the level of fuel therein as determined by the height of the upper edges of the weirs 267. These bosses are separated at the forward end of the air horn section by a gap 307 through which fuel may flow down into the fuel bowl from the vertical hole 287. The bosses curve around and rearward from the forward end of the air horn section and have downwardly extending

baflles

309 and 311 at their rearward ends which extend down nearly to the bottom of the fuel bowl. substantially filling the forward U-shaped fuel bowl chamber 277 and with

baffles

309 and 311 between the rearward fuel bowl chambers 275 and the rearward ends of the two sides of the U-shaped fuel bowl chamber 277, forward surging of fuel from the rearward chambers 275 into the sides of the U-shaped chamber 277 on sudden decleration of the vehicle (as on a panic stop of the vehicle) such as would drop the head of fuel in chambers 275, and rearward surging of fuel from U-shaped chamber 277 into the, rearward chambers 275 on sudden acceleration of the vehicle such as would increase the level of fuel in chambers, are both substantially pre- With

bosses

303 and 305 1 eluded. Also, while forward surging of fuel from the rearward chambers may result in some fuel spilling over the weirs 267 into the overflow chamber, since chambers 275 are relatively small and since the weirs are relatively narrow as regards the total, width of chambers 275, whatever drop in the head of fuel in chambers may occur is minor. With step-up cylinder 259 between the relatively small chambers 275, cornering of the vehicle has at most only minor effect on the head of fuel in these chambers.

The two metering jets 279 (FIGS. 4, 6, and 7) are threaded in tapped holes 313 in the bottoms of rearward fuel bowl chambers 275 at opposite sides of the step-up cylinder 259 in close proximity to the respective fuel wells 253. Each hole 313 extends downward into an inclined fuel passage 315 drilled in a boss 317 on the bottom of the main body 201 to an intersection with the lower end of the respective fuel well' 253. The outer end of each passage 315 is plugged as indicated at 319. The arrangement is such that, as to each mixture conduit 211, fuel for high-speed operation (i.e., throttleopen) is drawn from a fuel system which comprises the respective fuel chamber 275 down through the respective metering jet 279, the respective passage 315, the respective well 253, the respective main fuel tube 255 and the respective fuel passage 249 and nozzle 251. With a constant head of fuel in each chamber 275 over the respective metering jet 279, the rated flow of fuel is dependent upon the difference in air pressure on the fuel in the fuel bowl B and at the outlets of nozzles 251, and on the setting of two step-up rods 281.

the step-up rods are biased upward to a raised retracted position by a spring 325 which reacts from the bottom of bore 263 against the bottom of the piston. The raised retracted position of the piston and the rods is determined by engagement of the head 321 with the-head of a stop screw 327. The piston has a reduced upperend portion 329 carrying the head 321. A compression spring 331 surrounds portion 329 of the piston, reacting from a collar-333 slidable on portion 329 upward against the head 321. On downward movement of the piston, collar 333 engages an annular shoulder 335 adjacent the upper end of the step-up cylinder bore 263, and then the force of spring 331 is added to the force of spring 325 to supplement the upward bias on the piston and step-up rods. Piston 323 has a vent 337. Body 201is formed with a passage 339 extending from the lower end of the step-up cylinder bore registering with a passage 341 in the throttle body 209. These

passages

339 and 341 together constitute a vacuum passage placing the lower end of step-up cylinder bore 263 'in communication with the intage manifold 7 of the engine 3 for operation of the piston 323 and step-up rods 281in responsise to intake manifold vacuum.

Each step-up rod 281 has a lower end portion or step 343 of reduced diameter. These steps are raised out of the orifices of the metering jets 279 when piston 323 and rods 281 are raised. With steps 343 out of the metering jet orifices, the restriction imposed by the jetsto flow of fuel from fuel bowl chambers 275 to nozzles 251 is a minimum, and fuel may flow to nozzles 251 at a rate such as to provide a relatively rich or power air/fuel mixture tothe engine. This condition occurs, for example, during high load operation of the engine (wide open throttle) when the vacuum in the intake manifold of the engine and hence in the lower end of the step-up cylinder 259 is relatively low. During intermediate load operation of the engine (part-throttle operation) with consequent intermediate vacuum in the lower end of the step-up cylinder, the piston 323 is drawn part-way down against the bias of spring 325 only to the point where steps 343 are entered in the metering jet orifices, and the flow through the orifices is restricted so that a leaner mixture is supplied to the engine. During light load operation of the engine,

with consequent high vacuum in the lower end of the stepup cylinder, the piston 323 is drawn all the way down against the bias of both

springs

325 and 331 to the point where full-diameter portions of the rods 281 above the steps 343 are entered in the metering jet orifices, and the flow through the orifices is further restricted so that a still leaner economy mixture is supplied to the engine.

As disclosed in FIG. 7, for example, a head 345' is secured on top of the cluster body 243 bytwo tubular screws 347 extending through holes 349 in the head, holes 351 in body 243 and threadedin tapped holes 353 in ofiset 237. Head 345 closes off fuel passages 249. Body 243 has two vertical holes 355 and carries two idle tubes 357 extending down from these holes into the fuel wells 253 in offset 237. Each tubular screw has radial ports 361. Body 243 has grooves 363 in the top closed off by head 345 'to provide passages from the upper ends of vertical holes 355 to holes 349 and ports 361. Holes 353 are connected by passages 354, respectively, to recesses 367 in throttle body 209 adjacent the throttle bores 219. An idle discharge port 369 and an idle needle port 371 extend from each recess 367 into the respective thnottle bore 219. For each idle needle port 371 there is an idle mixture adjusting screw 373 threaded in the throttle body 209.

Vents for the fuel wells 253 are provided in the cluster body 243 and head 345 as indicated at 375 (FIG. 6).

From the above, it will be apparent that fuel for idling is supplied to each throttle bore 219 via the respective idle tube 357, vertical hole 355, horizontal groove or passage 363, radial ports 361 in the screw 347 and down through the screw and hole 353 to recess 367, and thence through ports 369 and 371. Air bleeds into this idling system for mixture with the fuel through the upper end of the tubular screw. Each screw is formed with a restriction 377 which acts as an economizer. Each idle discharge port 369 is a vertical slot located so that it is partially covered by the respective throttle valve 223 when the throttle valves are seated in the throttle bores 219. Each idle needle port 371 is located below the respective id-le discharge port Secured on the left end of the throttle shaft 221 is a throttle arm 379 (see FIG. 3). This is adapted to receive a connection from the usual accelerator pedal of the vehicle, with the usual spring in the connection tending to rotate the throttle arm and shaft in throttle-closing direction (which is counterclockwise as viewed in FIGS. 3, 5 and 6). The throttle arm379 is engageable with a screw 381 adjustably threaded in a lug 383 on the throttle body 209 for determining the normal idle position of the throttle valves 223. A fast We cam 385 is journaled on the left end of the choke shaft 225. This is weighted as indicated at 387to tend to swing clockwise as viewed in FIG. 3 and thereby to tend to back off from starting position. The backing off of the fast idle cam is controlled by engagement of a tail 389 of the cam with a tang 391 on a lever 393 fixed on the choke shaft 225. The arrangement is such that when the choke valve 227 is closed, the fast idle cam is held by tang 391 in starting position. When the choke valve opens, tang 391 allows the cam to back off from its starting position. When the choke valve closes, tank 391 pushes the cam back to starting position. A fast idle arm 395 is pivoted at 397 on the left side of the main body 201. This carries a fast idle screw 399 adapted to engage the surface of the fast idle cam 385. A fast idle link 401 connects throttle arms 379 and fast idle arm 395. The arrangement is such'that as the throttle arm swings in throttle-closing direction (counterclockwise as viewed in FIG. 3), arm 395 is swung counterclockwise to swing the screw 399 toward the fast idle cam. Engagement of screw 399 with the cam determines a fast idle position of the throttle arm 379 and the throttle valves 223.

A shaft 403 (FIGS. 1 and 3) is journaled in bearingsconnects throttle arm 379 and a crank 411 secured on the outer end of the shaft 403. A crank having two arms M3 and 415 is secured on the inner end of shaft 403. Arm 413 extends into an elongate slot 416 (FIGS. and 8) in an accelerating pump rod 417, which extends vertically through an opening 418 in air horn section 207. Rod 417 carries pump piston 419 at its lower end slidable in bore 265 of the accelerating pump cylinder 261. A coil compression spring 421 surrounding the pump rod. biases the pump piston 419 and pump rod 417 down ward. The arrangement is such that with the throttle valves 223 closed, arm 413 holds the pump rod and pump piston in the raised position in which they appear in FIG. 5. As the throttle valves are opened, link 409 rotates shaft 403 in such direction as to move the free end of arm 413 downward, and spring 421 thereupon drives the pump piston 419 downward through a pumping stroke. Fuel is adapted to enter the lower end of the pump cylinder 261 from the U-shaped fuel bowl chamber 277 via a pump inlet passage 423 (see FIGS. 4 and 5) in body 201 provided withan inlet ball check valve 425. Fuel is adapted to be discharged from the pump cylinder 26]. on a downward stroke of the pump piston 419 through a pump delivery passage 427 provided in the main body 201 extending to the shoulder 239 where it contains an outlet ball check valve 429. The venturi cluster body 243 (FIG. 5) is formed with a bottom recess 431 for receiving fuel from passage 427, and has pump jets 433 providing for communication from recess 431 to a top recess 435. in body 243. Fuel entering recess 435 from recess 431 is mixed with air-entering recess 435 via ai-r passage 437 provided in the air horn section 207, the main body 201, the cluster 243 and the head 345, and the mixtureis sprayed out into the mixture conduits 211 through orifices 439 in the cluster body 243.

A pin 441 received in crank

arms

413 and 415 extends through a hole 443 at the upper end of a bar 445 (see FIGS. 1, 4, 6, 8 and 12) for actuating the fuel inlet metering pin 295. This bar 445 is vertically slidable in a guide slot 447 (see FIG. in the air horn section 207. It extends down through this slot into the U-shaped fuel bowl chamber-277 and has a curved arm 449 extending from its lower end in a space 451 between boss 305 and the wall 229 around to the forward end of chamber 277. At its forward end, arm 449 has a split ear 453 in which is pinched the lower end of the metering pin 295. The arrangement is such that as the throttle arm 379 rotates clockwise to open the throttle valves 223, bar 445 is driven downward to lower the metering pin 295, and vice versa. When the throttle'valves 223 are at idle, the metering pin 295 occupies a raised position in which the annular orifice around the tapered upper end portion of the pin is of minimum area for minimum flow of fuel into the fuel bowl B. As the metering pin moves down, the area of this annular orifice increases for increased flow of fuel'into the fuel bowl. The position of the metering pin determines the back pressure in the primary chamber 159 of pump P.

The air horn section 207 is provided with a hole 455 for venting vapors from the fuel bowl B to the outside of the carburetor. This vent hole is adapted to be closed by a vent valve constituted by a leaf spring 457 having one end fixed at 459 on the air horn section and carrying a valve button 461 for' closing the vent hole. The free end of the leaf spring 457 is engageable by an arm 463 on shaft 403, the arrangement being such that spring 457 is bent up and button 461 is raised to open up the vent hole 455 when the throttle valves 223 are at idle, spring 457 being released for closing off the vent hole as the throttle valves are opened. Thus, the fuel bowl B is vented via hole 455 at idle, the hole being closed whenever the throttle valves are opened.

The air horn section 207 is formed with a choke cylinder 465 in which is slidable a choke piston 467.

Piston 467 is connected to the choke valve 227 by a link 469. The choke cylinder is formed with a longitudinal groove 471 adapted to by-pass air around the piston. Passaging as indicated at 473 is provided for placing the outer end of the choke cylinder in communication with the intake manifold of the engine so that piston 467 is responsive to manifold vacuum. Choke shaft 225 has an arm 475 at its right end adapted for connection of a link from a thermostatic control (not shown) responsive to engine temperature to control the choke valve and the fast idle cam in response to engine temperature. This thermostatic control may, for example, include a thermostatic coil located in a heat pocket in the cross-over passage of the exhaust manifold of the engine. The fast idle arm 395 has an unloader extension 477. This is adapted to engage the tail 389 of the fast idle cam 385 when the arm 395 swings clockwise on full opening of the throttle valves 223 thereby to open the choke valve 227 for unloading. This opening of the choke valve is accomplished by engagement of tail 389 with tang 391 on lever 393.

Fuel is delivered through line 25 to the fuel bowl B of carburetor C, in amount depending on the position of fuel inlet metering pin 295 of the carburetor. The position of the metering pin depends on the position of the throttle valves 223 of the carburetor, hence reflects the engine fuel demand. On high demand, pin 295 is down for relatively high delivery of fuel. On low demand, pin 295 is up for relatively low delivery of fuel. Thus, pump means may be used to supply fuel to carburetor C at a rate in excess of engine fuel demand so as to maintain fuel in the carburetor bowl chambers 275 at the level of the tops of the weirs 267, and also to scavenge overflow fuel which has flowed over the weirs into overflow chamber 0.

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.

I claim:

1. A carburetor for an internal combustion engine having a mixture conduit section formed to provide first and second vertical mixture conduits located sid'e-by-side and a fuel bowl section, said fuel bowl section being formed to provide an overflow chamber located generally centrally of said mixture conduits and a fuel bowl having a first fuel chamber adjacent the first mixture conduit and a second fuel chamber adjacent the second mixture conduit and a portion extending around the overflow chamber from one of said fuel chambers to the other, said fuel chambers being separated by a wall extending from the mixture conduit section to the overflow chamber, an inlet for delivery of fuel to said portion of the fuel bowl to supply fuel to said fuel chamber, a fuel system for supplying fuel from the first fuel chamber to the first mixture conduit, a fuel system for supplying fuel from the second fuel chamber to the second mixture conduit, each fuel chamber being separated from the overflow chamber by a weir extending laterally outward from said wall, and an outlet for drainage of fuel from the overflow chamber.

2. A carburetor as set forth in claim 1 further comprising baflfies extending downward into said portion of the bowl nearly to the bottom of the bowl for reducing surging of fuel between said fuel chambers and said portion of the bowl.

3. A carburetor as set forth in claim 1 wherein each fuel system includes a metering jet at the bottom of the respective fuel chamber, and wherein said wall is formed to provide a vacuum cylinder, said carburetor further comprising a piston in said cylinder and a pair. of metering rods, one for each jet, means connecting said piston and said metering rods and movable by said piston and means for moving said piston.

d. Acarburetor as set forth in claim 1 further corrv prising an accelerating pump cylinder located generally centrally of the fuel bowl section and a pump piston in the pump cylinder, means for moving said pump piston, the overflow chamber extending from one weir around the pump cylinder to the other weir.

5. A carburetor comprising a body including a mixture conduit therethrough and a wall defining a fuel bowl, a wall structure including a U-shaped wall having legs symmetrically disposed about a longitudinal axis of said carburetor and dividing said fuel bowl into a fuel bowl chamher and an overflow chamber, the legs of said U-shaped wall being directed toward said mixture conduit, means forming a fuel inlet into said fuel bowl chamber and a fuel outlet from said overflow chamber, said fuel inlet and outlet being disposed on said longitudinal axis, a weir between the legs of said U-shaped wall separating said chambers, said weir being of a fixed height above the bottom of said fuel bowl chamber to determine the fuel level therein, bafile means extending from said U- shaped wall outwardly to said fuel bowl wall and forming therewith and with said weir a rearward chamber within said fuel bowl having means defining an opening, said carburetor body being formed with a fuel passage extending from said opening in said rearward chamber to said mixture conduit.

6. A carburetor for an automotive vehicle and comprising a body having a front portion adapted to be positioned toward the front of the vehicle and a rear portion adapted tobe positioned toward the rear of the vehicle, said carburetor body including a pair of fuel and air mixture conduits formed through said rear portion of said body and a wall defining a closed fuel bowl formed in said front portion of said body, a substantially U-shaped walldisposed within said fuel bowl having legs disposed symmetrically about a longitudinal front-to-rear axis of said carburetor body with the legs of said U-shaped wall extending rearwardly toward said mixture conduits and spaced from the wall of said fuel bowl, said U-shaped wall dividing said fuel bowl into a fuel bowl chamber outside said U-shaped wall and an overflow chamber enclosed therein, weir structure extending between said chambers from said legs of said U-shaped wall inwardly to the wall of said fuel bowl, said weir structure being of a fixed height above the bottom of said fuel bowl chamber to determine the fuellevel therein, baffle structures extending substantially in a common vertical plane between said U-shaped wall legs outwardly to said fuel bowl wall and forming therewith and with said weir structure a pair of lateral rearward chambers within said fuel bowl, said baflle structure having spaced portions providing restricted openings between said fuel bowl chamber and each one of said respective lateral rearward chambers, said carburetor body being formed with a different fuel passage extending from each lateral rearward chamber to a different one of said fuel conduits, and means forming a fuel inlet. into said fuel bowl chamber and a fuel outlet from said overflow chamber.

7. A carburetor for an automotive vehicle and comprising a bodyhaving a front portion adapted to be positioned toward the front of the vehicle and a rear portion adapted to be positioned toward the rear of the vehicle, said carburetor body including a pair of fuel and air mixture conduits formed through said rear portion of said body and a wall defining a closed fuel bowl formed in said front portion of said body, said fuel bowl being symmetrically disposed horizontally about a longitudinal front-to-rear axis of said carburetor body, said fuel bowl at the rear end thereof having a reentrant wall portion, a substantially U-shaped wall having legs symmetrically disposed within said fuel bowl and spaced from the wall of said fuel bowl with the legs of said U-shaped wall extending rearwardly toward said mixture conduits, said U-shaped wall dividing said fuel bowl into a fuel bowl chamber outside said U-shaped wall and an overflow chamber enclosed therein, a first weir extending from one leg of said U-shaped wall inwardly to the reentrant wall portion of said fuel bowl, a second weir extending from the other leg of said U-shaped wall inwardly to the said reentrant wall portion, said weirs separating said chambers and being of a fixed height above the bottom of said fuel bowl chamber to determine the fuel level therein, baflie structures extending between both of said U-shaped wall legs outwardly to said outer fuel bowl wall and forming therewith a pair of lateral rearward chambers with said weirs and said reentrant Wall portion, said baffle structures having spaced portions providing restricted openings between said fuel bowl chamber and each one of said respective lateral rearward chambers, said carburetor body being formed with a different fuel passage extending from each lateral rearward chamber to a different-one of said fuel conduits.

8. The invention of claim 7 including means forming a fuel inlet into said fuel bowl chamber and a fuel outlet from said overflow chamber, said fuel inlet and outlet being disposed on said front-to-rear axis.

9. The invention of claim 8 wherein said reentrant wall portion is formed with an accelerating pumping means for providing accelerating fuel from one of said rearward chambers to said mixture conduits.

10. A carburetor for an automotive vehicle and comprising a body having a front portion adapted to be positioned toward the front of the vehicle and a rear portion adapted to be positioned toward the rear of the vehicle, said carburetor body including a pair of fuel and air mixture conduits formed through said rear portion of said body and a wall defining a closed fuel bowl formed in said front portion of said body, said fuel bowl having leg portions and a substantially U-shaped configuration symmetrically disposed horizontally about a longitudinal front-to-rear axis of said carburetor body and with the leg portions of said fuel bowl formed by an outer wall and a reentrant wall portion and extending toward said rear body portion, a substantially U-shaped arcuate wall having legs symmetrically disposed within said fuel bowl about said front-to-rear axis and spaced from the wall of said fuel bowl with the legs of said U-shaped-wall extending in the same direction as the walls of said fuel bowl, said U-shaped wall dividing said fuel bowl into a fuel bowl chamber outside said U-shaped wall and an overflow chamber enclosed therein, a first weir extending from one leg of said U-shaped wall inwardly to the reentrant wail portion of said fuel bowl, a second weir extending from the other leg of said U-shaped wall inwardly to the said reentrant wall portion, said weirs separating said chambers and being of a fixed height above the bottom of said fuel bowl chamber-to determine the fuel level therein, baflle structures extending substantially in a common vertical plane between both of said U-shapcd wall legs outwardly to said outer fuel bowl wall and forming therewith a pair of lateral rearward chambers within said fuel bowl chamber at the ends of the respective legs of said fuel bowl, said baffle structure having spaced portions providing restricted openings between said fuel bowl chamber and each one of said respective lateral rearward chambers, said carburetor body being formed with a different fuel passage extending from each lateral rearward chamber to a different one of said fuel conduits.

11. The invention of claim 10 wherein said fuel bowl chamber includes a fuel inlet and said overflow chamber includes a fuel outlet, said fuel inlet and outlet being disposed on said front-to-rear axis, said reentrant wall portion being symmetrically disposed to said front-to-rear axis and including an accelerating pump cylinder disposed on said axis and substantially coaxial to said arcuate U- shaped wall, accelerating pumping means including a piston within said pump cylinder for providing accelerating fuel from one of said rearward chambers to said mixture conduits.

A carburetor for an automotive vehicle and comprising a body'having a front portion adapted to be positioned toward the front of the vehicle and a rear portion adapted to be positioned toward the rear of the vehicle, said carburetor body including a pair of fuel and air mixture conduits formed through said rear portion of said body and a wall defining a closed fuel bowl formed in said front portion of said body, said fuel bowl having leg portions and a substantially U-shaped configuration symmetrically disposed horizontally about a longitudinal front-to-rear axis of said carburetor body and with the leg portions of said fuel bowl formed by an outer wall and a reentrant wall portion and extending toward said rear body portion, a substantially U-shaped wall having legs symmetrically disposed within said fuel bowl and spaced from the wall of said fuel bowl with the legs of said U-shaped wall extending in the same direction as the walls of said fuel bowl, said U-shaped wall extending from the bottom to the top of said fuel bowl and dividing said fuel bowl into a fuel bowl chamber outside said U-shaped wall and an overflow chamber enclosed therein, a first weir extending from one leg of said .U-shaped wall inwardly to the reentrant wall portion of said fuel bowl, 7

a second weir extending from the other leg of said U- shaped wall inwardly to the said reentrant wall portion, said weirs separating said chambers and being of a fixed height above the bottom of said fuel bowl chamber to determine the fuel level therein, a first pair of baflles extending substantially in a common vertical plane between said one U-shaped wall leg outwardly to said outer fuel bowl wall and and forming a first lateral rearward chamber within said fuel bowl chamber at the end of the respective leg of said fuel bowl, a second pair of baflles extending substantially in said vertical plane between said other U-shaped wall leg outwardly to said outer fuel bowl wall and forming a second lateral rearward chamber within said fuel bowl chamber at the end of the other leg of said fuel bowl, each of said pairs of baffles including a first bafile having a free end extending from the top of said fuel bowl downwardly to a point below the height of said weirs and a second baflle extending upwardly from the bottom of said fuel bowl toward said free end of said first bafile and terminating close to the free end of said first bafile to provide a restricted opening between said fuel bowl chamber and said respective lateral rearward chamber, said carburetor body being formed with a difierent fuel passage extending from each lateral rearward chamber to a different one of said mixture conduits.

References Cited by the Examiner UNITED STATES PATENTS 1,323,415 12/ 19 Sherbondy 261-72 1,440,930 1/ 23 Mott 261-72 1,861,781 6/32 Bracke 261-72 2,458,256 1/ 49 Crozier et al. 261-72 2,592,513 4/52 Haeusler 261-72 2,596,429 5/52 Orr 261-51 2,757,914 8/56 Ball 261-72 2,771,282 11/56 Olsonet al 261-72 2,796,242 6/57 Sarto 261-72 2,828,952 4/ 58 Winkler 261-72 2,977,099 3 61 Ball.

3,003,753 10/61 Johnson 261-72 FOREIGN PATENTS 804,142 4/51 Germany.

HARRY B. THORNTON, Primary Examiner.

HERBERT L. MARTIN, Examiner.

Claims

5. A CARBURETOR COMPRISING A BODY INCLUDING A MIXTURE CONDUIT THERETHROUGH AND A WALL DEFINING A FUEL BOWL, A WALL STRUCTURE INCLUDING A U-SHAPED WALL HAVING LEGS SYMMETRICALLY DISPOSED ABOUT A LONGITUDINAL AXIS OF SAID CARBURETOR AND DIVIDING SAID FUEL BOWL INTO A FUEL BOWL CHAMBER AND AN OVERFLOW CHAMBER,. THE LEGS OF SAID U-SHAPED WALL BEING DIRECTED TOWARD SAID MIXTURE CONDUIT, MEANS FORMING A FUEL INLET INTO SAID FUEL BOWL CHAMBER AND A FUEL OUTLET FROM SAID OVERFLOW CHAMBER, SAID FUEL INLET AND OUTLET BEING DISPOSED ON SAID LONGITUDINAL AXIS, A WEIR BETWEEN THE LEGS OF SAID U-SHAPED WALL SEPARATING SAID CHAMBERS, SAID WEIR BEING OF A FIXED HEIGHT ABOVE THE BOTTOM OF SAID FUEL BOWL CHAMBER TO DETERMINE THE FUEL LEVEL THEREIN, BAFFLE MEANS EXTENDING FROM SAID USHAPED WALL OUTWARDLY TO SAID FUEL BOWL WALL AND FORMING THEREWITH AND WITH SAID WEIR A REARWARD CHAMBER WITHIN SAID FUEL BOWL HAVING MEANS DEFINING AN OPENING, SAID CARBURETOR BODY BEING FORMED WITH A FUEL PASSAGE EXTENDING FROM SAID OPENING IN SAID REARWARD CHAMBER TO SAID MIXTURE CONDUIT.