US2971749A - Carburetion system and method - Google Patents

Description

Feb- 14, 19 1 w. E. LEIBING 2,971,749

CARBURETION SYSTEM AND METHOD Filed July 14, 1959 a Sheets-Sheet 1 '5 4 2 N I g a; 52 33 g m o lo v1 3] 2 a, I}: D01 g1" 38 Lx INVENTOR.

I II WILLIAM E. LEIBING WzaM w ATTORNEY Feb. 14, 1961 w. E. LEIBING CARBURETION SYSTEM AND METHOD 3 Sheets-Sheet 2 Filed July 14, 1959 MQ In: ll|llpmlll -32 34 NS WILLIAM E. LEIBING ATTORNEY Feb. 14, 1961 w. E. LEIBING 2,971,749

CARBURETION SYSTEM AND METHOD Filed July 14, 1959 3 Sheets-Sheet 5 axe u l\/ INVENTOR. FIG. z/mum E. LElBlNG ATTORNEY United States Patent CARBURETION SYSTEM AND NIETHOD William E. Leibing, South Pasadena, Calif. (P.0. Box 163, Cambria, Calif.)

Filed July 14, 1959, Ser. No. 827,089 14 Claims. c1. 261-47) The present invention relates to the formation of fuelair mixtures for internal combustion engines and more particularly to a carburetion system and method.

One of the contributing factors to air pollution in large metropolitan areas in this country is the presence of a relatively high percentage of unburned hydrocarbons in the exhaust of automobiles, buses and trucks. This unburned fuel in the exhaust may average as high as ten percent of all the fuel delivered to the engine and is the result of a number of different causes or conditions in the engine and carburetion system, the principal contributing factors being incomplete vaporization of the fuel before the fuel-air mixture reaches the engine and the formation undercertain conditions of a mixture too lean to fire in the cylinders. In the first instance, the fuel metered and discharged into the air supply to the engine is generally substantially correct for complete combustion but as a result of incorrect manifold design and/or improper hot spot temperatures a substantial portion of the fuel fails to vaporize in the induction system and passes through the cylinders into the exhaust, thereafter vaporizing and remaining suspended in the lower strata of the atmosphere.

The second mentioned situation usually occurs while the vehicle is coasting downgrade or decelerating from a rather high rate of speed. During this deceleration or coasting, the vehicle usually drives the engine, and, since the throttle valve of the carburetor is closed, the vacuum in the intake manifold rises substantially above that existing during normal engine idling. Mixtures formed under these conditions are often extremely lean and will not ignite in the cylinders. The unignited charges are discharged from the cylinder through the exhaust pipe into the atmosphere as raw or partially burned fuel, or are fired in the exhaust or muffler. The principal object of the present invention is to eliminate or reduce to a minimum the amount of unburned hydrocarbons in the exhaust gases of automobiles, buses, and trucks.

Another object of the invention is to provide a carburetor system and method of operation for discharging into the air flow to the engine substantially the correct metered amount of fuel and thereafter removing from the air any unvaporized fuel before the mixture reaches the engine.

Still another object of the invention is to provide a device mounted on an internal combustion engine between the carburetor and intake manifold for eliminating from the fuel-air mixture the unvaporized fuel by either returning it to the liquid supply system to be reintroduced into the air supply or collecting it and reintroducing it directly in the air flow between the carburetor and manifold.

A further object is to provide a device for performing the aforementioned functions, which can be mounted on the engine without requiring any substantial changes in the carburetor, air cleaner or intake manifold.

Another object of the invention is to provide a device 7 2,971,749 Patented Feb. 14, 19 1 induction system, showing it mounted on the intake manifold of an internal combustion engine;

Figure 2 is a horizontal cross sectional view of a portion of the present system, taken on line 2-2 of Figure 1;

Figure .3 is a partial elevational and vertical cross sectional view of a modified form of my fuel induction system, showing it mounted on the intake manifold of an internal combustion engine;

Figure 4 is a horizontal cross sectional view of a portion of my system, taken on line 4-4 of Figure 3;

Figure 5 is a vertical cross sectional view of a discharge jet and valve of an accelerating pump adapted for use in the present system;

Figure 6 is a vertical cross sectional view of a modified form of the present fuel induction system; and

Figure 7 is a further modified form of my induction system.

Referring more specifically to the drawings, numeral 10 designates a manifold of a conventional internal combustion engine, such as those used in automobiles, trucks and buses, numeral 12 designates a float type carburetor, 14 an air cleaner mounted on the carburetor intake, and 16 my fuel-air mixture conditioner connected to the outlet of the carburetor and mounted on the intake manifold. For the purpose of the present description, the intake manifold, air cleaner and carburetor may be considered as conventional or standard units; consequently these units will not be described in detail herein. The engine on which the present induction system is mounted may be either of a V or an in-line cylinder arrangement of any suitable number and may vary over a wide range of horsepower. The present invention is primarily concerned with the mixture conditioner unit 16 and the function performed therein, though the functional relationship to the carburetor and manifold is important.

In the induction system shown in Figures 1 and 2, a carburetor having a horizontal induction passage 20 is preferably used since this type permits a low hood over the engine and eliminates the need for an elbow pipe between the conditioner unit 16 and the carburetor. The carburetor shown includes choke and throttle valves 22 and 24, a venturi 26 in the induction passage 20, and float chamber 27 connected thereto by a main discharge jet 28 and an idle system 30, the construction and arrangement of these parts shown in the drawings being only diagrammatical representations for the purpose of illustrating a complete induction system. The throttle valve is mounted on shaft 32 controlled manually by a suitable linkage (not shown). The carburetor is supported by a bracket 33 secured to the body thereof and to a suitable mounting on the engine.

The present fuel-air conditioning unit 16 shown in Figures 1 and 2 consists of an elbow-shaped body 34 having a flange 36 at its mixture inlet end for securing the carburetor thereto and a flange 38 at the mixture outlet end for securing the unit to the intake manifold 10 of the engine. An annular member 40 is mounted in the elbow-shaped body 34 on the downstream side of the curve and is provided with an upstanding flange 42 which forms an annular channel 44 adjacent the internal wall of the body for collecting any liquid fuel flowing along the wall of the body. As a result of the relatively sharply curved passage 46 in body 34 above member 40 and the high velocityof the fuel-air mixture flowing from the carburetor to the engine, any unvaporized fuel-in the mixture is thrown by'centrifugal force to the outside half of the internal surface of the body and deposited on said surface where it continues to accumulate until sufficient quantity has formed to permit flow along the surface toward the manifold. This flow of fuel is initiated and maintained partially by gravity and partially by impact of the fuel-air mixture flowing through the unit. The liquid fuel flows along the internal surface, into channel 44 of member 40 and is then reintroduced into the air stream through passages 48 in a plurality of spaced arms 50 extending inwardly from flange 42 to a small venturi 52 secured to and supported by said arms. Passages 48 are connected at their outer ends to channel 44 near the bottom thereof and at their inner ends to the throat of the small venturi. In order to increase the pressure removing-the liquid fuel from channel 44 and reintroducing it into the air stream, a large venturi 54 is preferably included in passage 46 at the discharge end of the small venturi.

A small amount of additional air is introduced into the mixture by a tube 56 extending through the wall of body 34 and into the intake end of venturi 52. This additional air assists in vaporizing the accumulated liquid fuel being reintroduced into the air stream and produces more effective atomization and vaporization of the liquid fuel as it leaves the small venturi. The amount of air flow through tube 56 is controlled by a valve 60 in body member 62 adapted to move to and from the upper end of tube 56 and to regulate the air flow from holes 66 to the tube. The valve is moved toward and away from the upper end of tube 56, thus reducing or increasing the amount of additional air admitted into the induction pas sage as the throttle valve is closed and opened, by a linkage 68 connected to the throttle valve shaft 32. The linkage consists of a bell crank lever 70 pivoted on arm 72 of the valve body, a rod 73 connecting one end of lever 70 with the valve and a rod 74 connecting the other end of lever 70 with an arm 76 secured rigidly to one end of the throttle valve shaft. Rod 74 contains a length adjusting device 78 so that the amount of air admitted through tube 56 can be adjusted and varied to suit requirements.

In the operation of the present system, the carburetor functions in the conventional manner discharging fuel into the induction passage either through the idle system or main discharge jet forming a fuel-air mixture having an excess of liquid fuel which would normally pass into the cylinders in an unvaporized state. The mixture flows at hi h velocity into passage 46 and as the air and vaporized fuel are deflected sharply downwardly, the liquid fuel entrained therein impinges on the wall on the outside portion and flows into channel 44. The suction created in the venturis and the impact of the air flowing through the passage 46 force the accumulated liquid fuel from the channel through passages 48 and venturi 52 where it mixes with the air admitted through tube 56 and then discharges into the air stream in a fully atomized and then vaporized condition. The amount of air introduced through tube 56 is increased and decreased as the throttle is opened and closed. It is thus seen that the system employs a method radically different from the conventional induction system, i.e. the present system first metering and discharging into the air stream the amount of fuel required to form the proper fuel-air ratio when the fuel is fully vaporized, removing the unvaporized fuel from the fuel-air mixture, and then reintroducing the fuel into the mixture in a condition for instantaneous vaporization, preferably with a small amount of additional air. V V

The embodiment of the fuel-air mixture conditioner illustrated in Figures 3 and 4 consists of a generally discshaped or spiral-shaped housing 120 having a mixture inlet pipe 122 extending tangentially from the marginal portion thereof and connected to the throttle body 124 of carburetor 112, and an outlet passage 126 extending downwardly from the center of the housing and being connected to the inlet opening of the intake manifold. In the construction shown the housing consists of upper and lower sections 128 and 130, respectively, joined together at their marginal edges 132 and 134 preferably by welding or soldering. Pipe 122 is secured rigidly in place between the two sections and is held firmly therein by a flange 136 extending along the pipe from the section, and pipe 126 which extends upwardly from the bottom of section is secured to said section by soldering or welding to form a fluid-tight joint between the two parts. The lower part of section 130 around pipe 126 contains a small depression or trough 138 which functions as a sump for collecting any liquid fuel which may be present in the fuel-air mixture. Liquid fuel in the housing is channeled to the sump by a low rib 140 extending in a sweeping curve from the outside edge of the housing chamber 144 to the edge of the sump. The inlet end of pipe 122 is provided with a flange 141 for securing the pipe to the throttle body of the carburetor, and pipe 126 is provided with a flange 142 for securing it to the manifold. Chamber 144 approaches a cylindrical shape modified by the downwardly sloping walls of section 130 to facilitate draining of the liquid fuel to sump 138, and the term cylindrical shape as used in the claims refers to, and is intended to include, various shapes such as modified cylindrical shapes and helical shapes.

The fuel-air mixture entering chamber 144 generally tangential to the wall of the housing at a high velocity swirls around in a clockwise direction, as viewed in Figure 4, and is discharged through outlet pipe 126. In view of the high velocity of the mixture, any unvaporized fuel in the mixture is thrown by centrifugal force outwardly along the internal wall A of the housing and is driven along the wall, particularly along the internal surface of section 130, by the clockwise flow of the air in chamber 144 until it reaches rib 140 where it is directed downwardly into sump 138. The air with the fully vaporized fuel remaining therein passes from the chamber through top end 148 of pipe 126 into the manifold.

The liquid fuel removed from the mixture and collected in the sump is preferably reintroduced into the air flow leaving the housing in order to maintain accurately the required fuel-air ratio. In the embodiment shown in Figures 3 and 4 the liquid fuel is removed from sump 138 by a venturi 150 and discharge jet 152 extending from a point near the bottom of the sump into the passage in the venturi. The fuel which is drawn from the sump by the reduced pressure in the venturi and discharged into the air stream is further atomized by a small jet of air supplied through tube 154 extending through the top of housing 120 and being connected to the air cleaner or to the inlet of the carburetor by a tube 156. The carburetor is adjusted to compensate for the addition of the small amount of air admitted into the mixture through tube 154. V

The carburetor may contain the conventional accelerating pump discharging into the carburetor induction passage; however, a delay in engine response to the extra charge of fuel may occur particularly if the initial air flow is low when the throttle is opened. Consequently it is usually'desirable to discharge the accelerating pump at a point in the induction system posterior to the conditioner unit 16. Figure 5 illustrates a suitable discharge jet and valve for the accelerating pump which remains unchanged in construction and position in the carburetor. This unit consistsof a discharge jet having a fuel outlet passage 182 controlled by a valve 184 seating over the outer end of the passage. The valve is contained in a body 186 having chambers 188 and 190 separated by a flexible fluid impervious diaphragm 192. The valve is urged away from its seat to permit the discharge of fuel by the fuel from the accel crating pump delivered to chamber 188 through tube 196. The valve remains fully closed except when the pump is dischargin In the operation of the modified system, the carbu retor functions in the conventional manner discharging fuel into the induction passage either through the idle system or main discharge jet, forming a fuel-air mixture which flows through pipe 122 into chamber 144 and is swirled around the chamber at a velocity sufiicient to remove the liquid fuel by centrifugal force. The liquid fuel is collected in the sump and is reintroduced into the mixture by discharge jet 152 in venturi 150, where it is atomized and thence vaporized before reaching the cylinders.

The unit shown in Figure 6 is a simplified form of the present invention shown in Figure 1 and having in effect all the elements of unit 16 previously described. Carburetor 112 is connected with manifold by an elbowshaped conduit 200 having a venturi 201 therein near the discharge end and a sump 202 adjacent the venturi at the end and on the outside internal wall of the curved portion 204 of the conduit. The sump is formed by a small baffie 206 engaging the wall of the conduit at the venturi and extending inwardly toward the air flow, thus forming a pocket or trough for receiving liquid fuel deposited on the internal outside wall A of curved portion 204 by centrifugal force created by the rapid flow of the fuel-air mixture through the elbow-shaped conduit. The liquid fuel collected in sump 202 is discharged again into the air stream through discharge tube 208 connecting the sump with the passage in the venturi; Impact pressure created by the air flow into the sump as well as suction in the venturi lifts the fuel from the sump through tube 208. Atomization and vaporization of this reintroduced fuel are facilitated by a small amount of air at high velocity discharged through tube 210, as explained in connection with tube 154.

A further modified form of the invention is disclosed in Figure 7, wherein the carburetor, manifold and air cleaner are the same as those shown in Figures 1 and 3. In this modified form the fuel is collected in the same manner as in housing 120 of Figures 3 and 4, i.e. in a sump 220, but instead of reintroducing the fuel into the air stream with the use of a jet and venturi, a pump 222 removes the fuel from the sump and'returns it to the carburetor fuel bowl or to the fuel tank. The pump shown consists of a cylinder 224 having a piston 226 moved to its intake position by a spring 223 reacting between the top end of the cylinder and an annular flange 230 on the upper end of the piston and moved to its discharge position by a rod 232 operated by a cam 234 driven from the engine by a suitable power takeoff. The lower end of the cylinder contains a port 236 and a check valve 238 seated on the outlet side of port 236 by a spring 240. The line to the fuel tank or bowl is connected to pump outlet passage 242. The cylinder below the piston when the latter is in its raised position is connected to sump 220 by a slot-like port 244. i

In the operation of the modified form shown in Fi ure 7, the liquid fuel is removed from the fuel-air mixture in the same manner asin the system shown in Figure 3 and collected in sump '220. The piston 226 is reciprocated 1D the cylinder and when it is in its retracted or raised position, liquid fuel flows through port 244, filling or partially filling the cylinder. As the piston is moved downwardly it first closes port 244 and then ejects the fuel entrapped in the cylinder through port 236 and passage 242 and returns the fuel to the fuel bowl or tank. A positive displacement pump such as the one shown in Figure 7 is required since his capable of operating effectively against the vacuum in chamber 144.

When the piston is first fully retracted, the vacuum in the pump cylinder is higher than that in chamber 144; consequently, the fuel readily flows from sump 220 into the cylinder. Once the piston has started to move downwardly, port 244 is closed and the fuel in the cylinder is forced under substantial pressure from the pump. In this modified form the liquid fuel may if desired be reintroduced into the air stream in pipe 126 by a suitable jet connecting passage 242 with the passage through said pipe.

The methods used in the several modifications disclosed herein are basically the same, i.e. they consist of forming a fuel-air mixture of substantially the correct proportions, though containing a substantial amount of unvaporized fuel, and then removing this unvaporized component and either returning it to the fuel bowl or tank or reintroducing it into the air stream in an atomized and easily vaporizable form. The carburetor by slightly enriching the mixture may be adjusted to compensate for the fuel removed from the mixture and returned to the bowl or tank so that the ratio of fuel-air of the mixture reaching the engine cylinders is correct for proper combustion.

While a number of embodiments of the invention have been described herein, other modifications and changes may be made without departing from the scope of the present invention.

1 claim:

1. In an induction system of an internal combustion engine having a manifold and a carburetor with a throttle valve therein: walls forming an induction passage between said carburetor and manifold having a substantially right angle curve therein, an annular member in 7 said passage forming an annular channel adjacent the walls thereof on the downstream side of said curve, a small venturi disposed in said passage and extending downstream from said annular member, three arms connected to said annular member and supporting said venturi, passages in said arms connecting said channel with said venturi, a large venturi around the outlet of said small venturi and adjacent the outlet of said passage, a tube extending through the wall of said passage to the inlet of said small venturi for supplying air thereto, a valve for controlling the flow of air through said tube, and a linkage connected to the throttle valve of the carburetor for increasing and decreasing the flow of air through said tube when the throttle valve is moved toward open and closed position, respectively.

2. In an induction system of an internal combustion engine having a manifold and a carburetor with a throttle valve therein: walls forming an induction passage between said carburetor and manifoid having a substantially right angle curve therein, an annular member in said passage forming a channel adjacent the walls thereof on the downstream side of said curve, a small venturi in said passage adjacent said annular member, a plurality of arms connected to said annular member and supporting said venturi, passages in said arms connecting said channel with said venturi, a large venturi around the outlet of said small venturi, a tube extending through the wall of said passage to the inlet of said small venturi for supplying air thereto, a valve for controlling the flow of air through said tube, and a linkage connected to the throttle valve of the carburetor for varying the flow of air through said tube.

3. in an induction system of an internal combustion engine having a carburetor and an intake manifold: walls forming a curved induction passage between said carburetor and manifold, an annular member in said passage forming a channel adjacent the walls thereof on the downstream side of the curve, a small venturi in said passage adjacent said annular member, a plurality of arms connected to said annular member and supporting said venturi, passages in said arms connecting said channel with said venturi, a tube extending through the 7 a V wall of said passage to the inlet of said small venturi for supplying air thereto, and a valve for controlling the flow of air through said tube. 7 I

4. In an induction system of an internal combustion engine having a carburetor and an intake manifold: wallsforming a curved induction passage, an annular member in said passage forming a channel adjacent the walls thereof on the downstream side of the curve, a small venturi in said passage adjacent said annular member, an arm connected to said annular member and supporting said venturi, a passage connecting said channel with said venturi, and a tube extending through the wall of said passage to the inlet of said small venturi for supplying air thereto.

5. In an induction system of an internal combustion engine having a horizontal carburetor and an intake manifold: a mixture conditioning device, comprising side, top and bottom walls forming a cylindrically shaped chamber, a mixture inlet conduit extending generally tangentially to said side wall to produce clockwise flow of mixture in said chamber and being connected to the outlet of the carburetor, a mixture outlet conduit extending vertically through said bottom wall and upwardly therefrom to an intermediate point between said bottom and top walls and being connected to the intake manifold, a sump in the bottom of said chamber adjacent said outlet conduit on the side thereof generally facing said inlet conduit, a curved ridge on. the internal surface of said bottom wall extending in a clockwise direction from the side wall to said sump, a venturi in said outlet conduit with the throat thereon on an approximate level with the top of said sump. a tube connecting said sump with the throat of said venturi for discharging fuel from said sump into said outlet conduit, and a tube having one end adjacent the discharge end of said first mentioned tube and the other end connected with the carburetor inlet passage.

6. In an induction system of an internal combustion engine having a carburetor and an intake manifold: a mixture conditioning device, comprising side, top and bottom walls forming a cylindrically shaped chamber, a mixture inlet conduit extending generally tangentially to said side wall to produce circumferential flow of mixture in said chamber and being connected to the outlet of the carburetor, a mixture outlet conduit extending vertically through said bottom wall and upwardly therefrom to an intermediate point between said bottom and.

top walls and being connected to the intake manifold, a sump in the bottom of said chamber adjacent said outlet conduit on the side thereof generally facing said inlet conduit, a means forming a trough-like structure on the internal surface or" said bottom wall extending in the direction of said mixture flow from the side wall to said sump, a venturi in said outlet conduit with the throat thereof on an approximate level with the top of said sump, a tube connecting said sump with the throat of said venturi for discharging fuel from said sump into said outlet conduit, and a tube having one end adjacent the discharge end of said first mentioned tube and the other end connected with a source of air.

7. In an induction system of an internal combustion engine having a carburetor and an intake manifold: a mixture conditioning device, comprising side, top and bottom walls forming a cylindrically shaped chamber, a mixture inlet conduit extending generally tangentially to said side wall to produce circumferential fiow of mixture in said chamber and being adapted to be connected to the outlet of the carburetor, a mixture outlet conduit extending vertically through said bottom wall and being adapted to be connected to the intake manifold, a sump in the bottom of said chamber adjacent said outlet conduit, a means forming a trough-like structure on the internal surface of said bottom wall extending in the direction of said mixture flow from the side wall to said sump, a venturi in said outlet conduit with the throat a mixture inlet conduit extending generally tangentially to said side Wall to produce circumferential flow of mixture in said chamber and being connected to the outlet of the carburetor, a mixture outlet conduit extending vertically through said bottom wall and upwardly therefrom to an intermediate point between said bottom and top walls and being connected to the intake manifold, a sump in the bottom of said chamber adjacent said outlet conduit on the side thereof generally facing said inlet conduit, a means forming a trough-like structure on the internal surface of said bottom wall extending in the direction of said mixture fiow from the side wall to said sump, and a means for removing liquid fuel from said sump and discharging it in said outlet conduit.

9. In an induction system of .an internal combustion engine having a carburetor and an intake'manifold: a mixture conditioning device, comprising side, top and bottom walls forming a cylindrically shaped chamber, a mixture inlet conduit extending generally tangentially to said side wall to produce circumferential flow of mixture in said chamber and being adapted to be connected to the outlet of the carburetor, a mixture outlet conduit extending vertically through saidbottom wall and being adapted to be connected to the intake manifold. a sump in the bottom of said chamber, and a means for removing liquid fuel from said sump.

10. In an induction system of an internal combustion engine having a carburetor and an intake manifold: a mixture conditioning device, comprising side, top and bottom walls forming a cylindrically shaped chamber, a mixture inlet conduit extending generally tangentially to said side wall to produce circumferential flow of mixture in said chamber and being adapted to be connected to the outlet of the carburetor, a mixture outlet conduit extending vertically through said bottom wall and being adapted to be connected to the intake manifold. and a sump in the bottom of said chamber adjacent said outlet conduit for returning liquid 'fuel to the carburetor.

l.'In an induction system of an internal combustion engine having a carburetor and an intake manifold: a mixture conditioning device. comprising side, top and bottom walls forming a cylindrically shaped chamber, a mixture inlet conduit extending generally tangentially to said side wall to produce circumferential flow of mixture in said chamber and being connected to the outlet of the carburetor, a mixture outlet conduit extendin vertically through said bottom wall and upwardly therefrom to an intermediate point between said bottom and top walls and being connected to the intake manifold, a sump in the bottom of said chamber adjacent said outlet conduit on the side thereof generally facing said in et conduit, a curved ridge on the internal surface of said bottom wall, a means forming a trough-like structure on the internal surface of said bottom wall extending in the direction of said mixture flow from the side wall to said sump, and a positive displacement pump connected to said sump for removing fuel therefrom and returning it to the source of fuel supply.

12. In an induction system of an internal combustion engine having a carburetor and an intakemanifold: a mixture conditioning device, comprising side, top and bottom walls forming a cylindrically shaped chamber,

a mixture inlet conduit extending genrally tangentially to said side wall to produce circumferential flow of mixture in said chamber and being adapted to be connected to the outlet of the carburetor. a mixture outlet conduit extending vertically through said bottom wall and being adapted to be connected to the intake manifold, a sump in the bottom of said chamber for collecting liquid fuel removed from said mixture, a pump having a cylinder with an inlet port communicating with said sump, a piston in said cylinder, a means or operating said piston, and an outlet passage for returning fuel to the source of fuel supply.

13. In an induction system of an internal combustion engine having a carburetor and an intake manifold: a curved induction pipe between said carburetor and manifold, a venturi adjacent the outlet end of said pipe, a rib across the outside curve on the internal wall of said pipe adjacent the inlet of said venturi forming a trough, and a tube connecting said trough with the throat of said venturi.

10 14. In an induction system of an internal combustion engine having a carburetor and an intake manifold: a curved induction pipe between said carburetor and manifold, a venturi adjacent the outlet end of said pipe, a trough adjacent the inlet of said venturi, and a conduit connecting said trough with the throat of said venturi.

References Cited in the file of this patent UNITED STATES PATENTS 992,260 Rush May 16, 1911 1,021,079 Stewart Mar. 26, 1912 1,036,812 Edmonson Aug. 27, 1912 1,526,963 Chandler Feb. 17, 1925 1,530,157 Edwards Mar. 17, 1925 2,083,752 Trussell June 15, 1937

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