US2611592A - Dual carburetor - Google Patents

Description

SePt- 23 1952 b. E. 'N'SON 2,611,592

' DUAL CARBURETOR Filed oct. 27, 194e 5 sheets-shane Sept. 23, 1952 D. E. ANDER'S'N DAL CABURETOR 5 Sheets-Sheet 3 p. .ANpRsQN 'i 2,611,592

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fn Veni. D z-f n 0 m E. M ,V/ d A Patented Sept. 23, 1952 UNITED STATES TENT OFFICE DUAL CARBURET OR Application October 27, 1948, Serial No. 56,793

The present invention relates to a dual carburetor and more particularly to a unitary carburetor for the feeding of both main fuel and supplemental fuel to an internal combustion engine in metered amounts and for forming a main fuelair mixture containing added supplementary fuel in amounts correlated with the operating conditions of the engine and suflicient to .prevent engine pre-ignition and detonation.

The desirability of employing supplementary fuel or fuel additives with the main hydrocarbonair mixture ignited within the combustion chambers of an internal combustion engine has been recognized. In the prior art the improvement of the main fuel has in general been accomplished in two ways. lFirst, additives, such as. tetraethyl lead, organic halogen compound and the like, have been added directly to the fuel for solution therein and subsequent injection to the main fuelair stream at all times during operation of the engine. Second, various types of devices for injecting supplementary fuel in accordance with the manifold vacuumof the engine have been proposed. These devices are typically mounted on the engine independently of the carburetor and` are vented directly to. the manifold vacuum of the engine for the introduction of. supplementary fuel in accordance therewith. Such devices are. an added expense since theyare provided independently of the main fuel injection system, are generally inefficient since supplementary fuel is not ini ected in strict accordance with engine requirements, and further make no provision for the introduction of additional supplemental vfuel on the sudden acceleration of the engine. such devices the supplementary fuel o-w rate remains constant under all engine operating co-nditions at which any supplementary fuel flow occurs.. V

Engine operating conditions, when measured in terms of intake manifold vacuum, may be divided into three general ranges. When the engine is operating at. high vacuums (100 inches Watervacuum and higher), engine knock and pre-ignition do not occur,4 while' operation alt-low vacuums (from about Ei to 70 inches `water vacuum l lis. very conducive to rough engine perfomance, knock andpre-ignition the absence. o-f anti-knock additives. 1n the intermediate range of operation (from. about '70 to. 10'0 inches Water vacuum), the engine knock may occur in the absence of supplementary fuelsI or anti-knock. additives; .although. lesser amounts. are requiredthan at the lower vacuums;v Upon sudden accelerationor op-f eration at' high speed and high load, thev engine Further, inl

6 Claims. (Cl. 261-18) functions at low vacuums and supplementary fuel is primarily required at these vacuums. However, supplementary fuel is also required during operation at intermediate vacuums, although in lesser quantities.

The present invention nowy provides a fuel carburetor for the feeding of both supplementary fuel and main fuel through separate injection systems into a common air intake venturi. Such a device is more compact, provides means Whereby additional supplemental fuel may be introduced by means of an accelerating pump, together with main fuel upon sudden acceleration of the engine, and also provides for the close correlation of fuel feeding with the engine performance throughout the entire range of' engine operating conditions, with supplementary fuel feeding occurring during intermediate engine vacuums and additional feeding at low vacuums.

The device of the present invention comprises generally a single casing provided with an air inlet conduit carrying spaced choke and throttle valves and a venturi mounted therebetween. The casing denes separate fuel float chambers connected to a source of main fuel and supplementary fuel respectivelyv and communicating with separate injection jets connecting the flow chambers with the air intake venturi. Each of the flow chambers is provided with diaphragm controlled valve means for regulating the flow of fuel therefrom in accordance With the intake manifo-ld pressure of the engine. Each of the chambers is also provided with a separate accelerating pump connected to a common nozzle forl injecting a mixture of main fuel and supplementary fuel to the air intake venturi upon the rapid acceleration of the engine caused by the sudden depression of the engine throttle control. Thus, an additional mixture of supplementary fuel and main fuel is fed to the engine during periods of rapid acceleration to. prevent preignition and detonation. positive mechanical means directlyv linked to the throttle control element for shutting off the now of supplemental fuel during those periods of operation at which the engine is operating at full throttle and high vacuum such as occurs at high spee The present invention thus provides a dual carburetor for the feeding of a main fuel-air mixture to the engine and the addition of supplementary fuel to this mixture in amount directly proportional to the operating characteristics of the engine. Means are provided for yfeeding supplementary fuel under medium man- The present invention alsov providesv ifold vacuum conditions, for feeding additional supplementary fuel under extremely low manifold vacuums, for feeding additional supplementary fuel during rapid acceleration of the engine, and for interrupting now of supplementary fuel by mechanical means during those periods in which the engine is operating at full throttle and high speed.

It is, therefore, an important object of the present invention to provide a unitary carburetor which meters fuel and air to an engine in intermixed relation with varying amounts of anti-detonant fluid being added to the main fuel-air mixture in amounts controlled by the intake manifold pressure and also if desired by the throttle opening movement.

Another important object of the present invention is to provide a dual carburetor for the feeding of main fuel and supplementary fuel to the intake manifold of an internal combustion engine, the carburetor having separate injection systems for each type of fuel and providing a main fuel-air mixture including metered amounts of supplementary fuel, the amount of supplementary fuel depending upon the operating conditions of the engine.

A further object of the present invention is to provide means for adding supplementary fuel to a main fuel-air mixture fed to an internal combustion engine in accordance with the intake manifold vacuum to prevent pre-ignition and detonation and also means operating independently of manifold vacuum to provide an extra 'supplementary fuel charge when the throttle is suddenly opened and means linked mechanically to the throttle actuating mechanism for cutting off the now of supplementary fuel when the engine is operating at full throttle and high speed.

A still further object of the present invention is to provide a dual carburetor for feeding main fuel and supplementary fuel to the intake manifold of an internal combustion engine, the carburetor having separate injection systems for each type of fuel, one of said systems feeding main fuel-air mixture in amounts correlated to the manipulation `of the throttle valve and to the engine intake manifold vacuum and the other system feeding supplementary fuel for admixture with the main fuel-air mixture in amounts sufficient to prevent engine pre-ignition and detonation, the amount of supplementary fuel being correlated with the manifold vacuum and the movement of the throttle valve to feed supplementary fuel to the engine in accordance with engine operating conditions, to provide an added supplemental fuel charge upon sudden opening movement of the throttle valve, and to interrupt the flow of supplementary fuel when the engine is operating at full throttle and high speed.

A yet further object of the present invention is to provide a method of preventing pre-ignition and detonation in internal combustion engines by feeding supplementary fuel to the main fuel-air mixture introduced into the engine in accordance with the engine intake manifold vacuum, supplying extra supplementary fuel charge in accordance with movement of the throttle valve when the valve is suddenly opened, and interrupting the ow of supplementary fuel when the engine is operating at full throttle and high speed, and also when engine is operating at part throttle at a medium high speed where the engine does not detonate.

Other and further important objects of this invention will be apparent from the disclosures in the specification and the accompanying claims.

On the drawings:

Figure 1 is a plan elevational view of a dual carburetor of the present invention;

Figure 2 is a side elevational View of the dual carburetor taken along the plane II--II of .Figure 1,'

Figure 3 is a cross-sectional View, with parts shown in evelation, of the carburetor of Figure 1 taken along the plane III-III of Figure 1;

Figure 4 is a top plan view of the carburetor with the carburetor casing top section removed;

Figure 5 is a cross-sectional view, with parts shown in elevation, taken along the plane V-V of Figure 1;

Figure 6 is a cross-sectional view, with parts in elevation, taken along the plane VI-VI of Figure 4;

Figure is a cross-sectional view, with parts shown in elevation, taken along the plane VII- VII of Figure 4;'and

Figure 8 is a schematic view of the entire dual carburetor of the present invention.

As shown on the drawings:

In Figure 1, reference numeral Ill refers generally to a dual carburetor of the present invention comprising generally a housing enclosing separate main fuel injection and supplementary fuel injection systems which cooperate for the feeding of main fuel and supplementary fuel to the engine to which the carburetor is attached in accordance with the operating conditions of the engine. Each of these systems will hereinafter be described in detail.

Casing and engine controls As shown in Figures l, 2 and 4, the casing enclosing the operating parts of the dual carburetor of the present invention comprises an upper casing section Ii, an intermediate casing section I2 and a lower casing section I3. The upper section Il is provided with a generally cylindrical, upstanding central boss hl provided with a central, open-ended aperture I5 defining the air inlet of the carburetor. The passage of air through the inlet I5 is controlled by a choke valve I8 mounted in the inlet on a pin Il extending thereacross. Movement of the choke valve I on the pin I'I is controlled by a choke lever I@ pivoted to the upper casing section Il on pin |8a and connected to the engine choke control through knob IBI).

Upper casing section II also carries a pair of upstanding port housings I9 and 20 connected to a suitable source of supplementary fuel and main fuel respectively. The upper casing section II is secured t0 the intermediate casing section l2 by suitable means, such as by screws 2l threadedly retained by bosses formed integrally with section I2.

The intermediate casing I2, as best shown in Figure 1, denes a pair of open topped float chambers 22 and 23 adapted to contain supplementary fuel and main fuel respectively. The chambers 22 and 23 are separated by a generally cylindrical, central boss 24 having an axially extending open ended aperture 25 extending therethrough. Boss 24 carries a venturi 26 mounted czzntrally thereof by means of supporting bosses The intermediate section I2 of the casing also carries a pair ofv upstanding exterior bosses 28 and 29 in communication with the flow chambers 22 and 23 respectively, as at 28a and 29a (Figure 4), and adapted to receive, accelerating pumps as hereinafter described.

The upper casing section Il carries bosses and 3| closed at their upper ends and adapted to register with the bosses 28 and 29 for closing the same to form the complete accelerating pump housing, as best shown in Figure 5.

The lower casing section I3 is secured to the intermediate casing section I2 by means of screws 32 (Figures 2 and 3) threadedly retained by the intermediate section, the lower casing section being formed with flange 33 adapted for securing the complete carburetor I0 to the intake manifold of an internal combustion engine. The lower casing section I3 is provided with an intermediate, generally cylindrical boss 34 carrying a throttle valve 35 (Figure 3) mounted on pin 36 pivotally carried by the boss 34. Pin 36 carries a throttle lever 31 having a depending knob 31a adapted to be connected to the throttle control rod or cable (not shown) of the engine. Throttle lever 31 is connected to links 36 and 38a (Figures 1 and 3) to accelerating pump actuating arm 39 for the main fuel accelerating pump housed in the casing defined by the sections 29 and 3I, the throttle lever also being connected through link 38h (Figures 2 and 5) to accelerating pump actuating arm 40 by the supplementary fuel accelerating pump housed in housing sections 28 and 36. valve 4I for controlling the admission of main fuel to the intake manifold during idling of the engine as hereinafter described.

M ein fuel injection system The main fuel injection system of the carburetor of the present invention is illustrated in Figures 3, 5 and 7 of the drawings, and comprises generally main fuel float chamber 23 (Figures 3 and 4) in which a oat 42 is pivotally mounted on a pin 43 carried by the chamber wall. Fuel is introduced into the float chamber 23 through main fuel inlet port 44 located in inlet port housing 2l), main fuel flowing through an orifice 45 formed in an orifice sleeve 46 threadedly retained within the housing 20. Admission of fuel to the orice is controlled by a needle valve 41 guided by sleeve 46, movement oi the valve 4 1 being controlled by the float 42 through float supporting arm 48. Float chamber 23 is vented to atmospheric pressure through Vent tube 49 extending into the air intake I5 (Figures l and 3). Tube 49 communicates with an air chamber indicated at 56 connected by passages 5I and 52 to the flow chamber 23. Port 53a in the walls of chamber 56 insures that the supply of air introduced through conduit 49 remains at atmospheric pressure despite possible pressure built up by the sudden rush of air into the air inlet I5.

The high speed main fuel injection system comprises generally a main jet 53 and means for feeding fuel and air to the jet 53. Jet 53 extends from flow chamber 23 to venturi 23 and comprises generally a boss 54 bored as at 55 and apertured as at 56 to connect chamber 23 with venturi 26, the bore 55 being threaded as at 55a. Tube 51 having a reduced diameter central portion is mounted within the bore 55 and extends axially therethrough into the venturi 26 adjacent the throat thereof. The tube 51 is apertured as at 58 and adjacent its tip 51al at 56a. A block 59 extends radially across the lower portion of the tube 51, and a nipple 6I), having an axially extending orice 6I and exterior threads, is retained in the threaded end of bore 55. Air is Boss 34 also carries an idling needle 6 bled into iet 55 through air chamber 62 defined by dome housing 63 adjacent the mouth of venturi 26 andI connected to an annular space between tube 51 and bore 55 and in communication with the aperture 58o through tubes 64.

During high speed operation of the engine, air flowing through venturi 26 will draw main fuel from the ilow chamber 23 through iet 53 into the venturi for adrnixture with the air flowing therethrough and subsequent introduction into the engine.

It has been found that the vacuum within th intake manifold of an internal combustion engine decreases during. those periods of operation of the engine which are particularly conducive to pre-detonation and knock. The carburetor of the present invention feeds main fuel into the intake manifold of the engine in larger amounts during those periods of operation most. conducive to knocks by means of a diaphragm controlled valve 65 located in float chamber 23, as illustrated in Figures 4. and 'l of the drawings. Valve 65 is mounted in a boss 66 extending upwardly into float chamber 23 and downwardly into vacuum chamber 61 defined by adjacent recessed portions of intermediate casing section I2 and lower cas,- ing section i3. Vacuum chamber 61 is vented to intake vacuum through. port 668, conduit 69 (Figure 4) and'port 'l0` (Figure. 3) communicating with the interior aperture of casing section I3 below throttle valve 35.,

An open-ended sleeve 'II having an axial bore 'I Ia is threadedly retained in the boss 66 and carries a flexible diaphragm 12 closing its open, flared lower extremity 1lb. Valve 65 is provided with a threaded Upper shank 65a extending above sleeve 1I, an intermediate conical seating face 65h and a reduced shank 65e extending through a restricted orifice 13 formed in the upper portion of the sleeve 1I, and the seating face 65h is adapted to. close the orifice 13. Valve 65 is secured to diaphragm 12 by washers mounted on either side of the diaphragm. A bonnet 14 is threadedly retained on the upper portion 65a of the valve 65 and a spring 15 extends between the, sleeve 1I and bonnet 14 to urge the conical seating face 65h away from the orice 13.

Outlet ports. 16 provide an exit for main fuel owing from float chambery 23 through the orifice 13 into the interior' of' sleeve 1I. A passage 11 provides egress for fluid from chamber 23 to main metering jet 53. A block 18 having a restricted orifice is mounted in the passage 11 for metering the uid owing therethrough.

The operation of valve 65 to meter fuel to the conduit 11 in accordance with the intake manifold vacuum of the engine will be readily appreciated. During operation of the engine at low or constant speed, the intake vacuum vented to the chamber 61 will be sufficient to draw the diaphragm 12 downwardly against the action of the spring 15 to seat the conical seating face 65h of the valve 65 againstl sleeve 1I, closing the orice 13. However, during periods of rapid acceleratio-n, high speed, or high load, the Vacuum within the chamber 61 will be reduced, the spring 15 will be able to overcome the resistance of diaphragm 12, and the spring 15 will unseat the valve 65 establishing the flow ofv fuel from the float chamber 23 through orifice 13, ports 16, and passage 11 into the main fuel jet 53.

As shown in Figures 3 and 1', fuel is introduced into idling jet' 'I9 through upwardly extending passagev 86 formed in boss 24 and connected to lateral passage 8l` communicating with downwardly extending passage 82 connected with passage 11 leading from iioat chamber 23 to main jet 53. When throttle valve 35 is closed, and engine inoperative, valve S5 is open since atmospheric pressure exists in chamber 61 and fuel stands in passage 11 and jet 53 at the level of fuel in float chamber 23. Tube 83 mounted in passage 82 extends into proximity with block 18 and the suction, generated by the use of the engine starter with the throttle valve closed, will be suflicient to draw fuel through passages 8| and 80 to J'et 19 and, following the first starting of the engine, a siphoning action will cause fuel iiow to continue. Air flowing through vent 83a. (Figure 3) and passage 84 will be bled' into the fuel stream passing through passage 69. Following the opening of throttle valve 35, fuel and air will also be admitted into the fuel intake through idling jet 85.

At intermediate throttle openings (between idling and full power) the vacuum in 61 will be high enough to keep valve 65 closed. The fuel then flows from 23 through 56 and then through 5| into jet 53 where the fuel is mixed with air flowing through 51a and thence into throat of venturi 26.

When the engine is undergoing rapid acceleration, usually caused by rapid opening of throttle valve 35, an extra charge of main fuel will be required, and this extra fuel charge may suitably be supplied by means of accelerating pump 86 illustrated in Figure 5 of the drawings. Pump 88 is positioned within the housing 29 and 3| formed integrally with casing sections I2 and I,

respectively, as hereinbefore described. i Pump e 86 comprises generally pump actuating arm 39 linked through throttle links 38 and 39o to the throttle lever 31 (Figure 2).. r.'he pump actuating arm 39 carries at its lower end a sleeve 31 slidable on the arm and provided with a depending, generally annular gasket B8 contacting the interior curved surfaces of housing 29. A coil spring 89 is retained on sleeve 81 to urge the gasket 88 outwardly against the walls of the housing 29.

An annular flange 9| is secured to the arm 39 intermediate the ends thereof and a coil spring 92 is compressed between the flange 9| and the sleeve 81. Since the sleeve 81 is slidably fitted on the arm 39, the spring 92 provides a resilient Y support for the entire sleeve 81 by permitting sliding movement of the sleeve relative to the arm. A second coil spring 93 is compressed between the upper interior surface of the housing 3| and the flange 9|, this spring urging the entire assembly consisting of the arm 39 and the sleeve 81 downwardly Within its housing.

Communication between the accelerating pump 96 and the interior of the oat chamber 23 is established through a ball check valve controlled conduit Sli connecting the chamber and the housing as best shown in Figure 4. Egress from the pump housing is provided through conduit 95 extending upwardly through one wall of the boss 24, as shown in Figure 4, the conduit leading into nozzle 93 (Figure 1) located in the air inlet I5 in a position adjacent the upper extremity of venturi 26. n

The operation of the pump 85 will be readily understood since upon upward movement of the actuating arm 39 main fuel is drawn from the float chamber 23 into the interior of the pump casing through the conduit 94, and upon downward movement of the actuating arm 39, as upon suddenly opening the throttle valve 35 as by means of the throttle lever 31, main fuel is forced from the housing through conduit 95 into the nozzle 96 the main fuel being introduced into the venturi through the nozzle 96.

Supplementary ,fuel injection ,system Supplementary fuel is injected through the dual carburetor of the present invention in a manner analogous to that hereinbefore described in connection with the main fuel charge introduced into the intake manifold of the engine. Supplementary fuel is injected under conditions of low vacuum at which pre-ignition and detonation are likely to occur in the absence of such feeding. The supplementary fuel injection system for feeding under low vacuum condition is illustra-ted in Figures 3, 4 and 6 of the drawings.

As particularly shown in Figure 3 of the drawings, supplementary fuel is fed from a suitable source through inlet 91 located in inlet housing i9 and orice 98 controlled by needle valve 99, the valve being actuated by float I pivoted to the casing at ||l|, as hereinbefore described in connection with float 42 in chamber 23. Float chamber 22 is vented to air through passage |02 4connected to passage 5 I. Fuel is fed through jet |93 in accordance with the manifold vacuum of the engine upon which the carburetor is mounted through diaphragm controlled spring urged valves |94 and |05 located in fluid chamber 22 and shown in Figures 4 and 6.

Valves |04 and |05 are similar in construction and operation to the valve 65 illustrated in Figure 7 and hereinbefore described. For example, valves |04 and |95 are mounted on a pair of bosses |06 `and |01, respectively, provided on either side of the main supplementary feeding jet |03. In valve |05 the valve body |138 is provided with a conical seating face |89 urged to open position away from orifice IID by a light coil spring I I I. Diaphragm 2 is mounted in vacuum chamber 3 vented to manifold vacuum through passage Illia (Figure 4) and, during periods of high vacuum, the diaphragm I I2 urges the conical seating face |09 to closed position to prevent the flow of supplementary fuel from the chamber 22 into the main metering jet ID3. Valve body ||4 of valve |04 is provided with a conical seating face I|5 urged away from orifice H5 by a pair of springs ||1 and H8 of different compressive strengths. The additional spring I I8 serves to maintain the valve seating face ||5 away from the orifice I I6 even though the vacuum chamber ||9 acting upon the diaphragm |28 1s fairly high, which vacuum, established in the vacuum chamber ||9 through the conduit |2| (Figures 3, 4 and 6), would be sufcient to overcome single spring H1. Thus, the valve |04 is open at fairly high intake manifold vacuums, yand feeding of supplementary fuel through the orifice IIB and conduit |22 into the main metering jet |63 will be possible even though fiow through the orice IIB of valve |05 and the conduit |23 then through |28 and orifice |29 into the metering jet |03 will be interrupted by seating of face |09 against the action of the spring I. A metering orifice |24 is provided in the conduit |22 to meter the iiow of supplementary fuel into the main jet |03 from the valve |04.

At high manifold vacuum both valves are closed, at low vacuum, such as obtains at full throttle, both valves are open. inasmuch as oriiices |24 and |23 are in. series, the larger or full power orifice |29 being placed after the small or part throttle orifice |24, when the full power consce valve is closed antidetonant fluid will flow only through the orifice |24.

Thus, it may be seen that the flow .of supplementary fuel through the valve |04 will take place under vacuums which are sufficient to close each of the valves 65 and |05. By the employment of the two valves |04 and |05, more accu'- rately metered flow of supplementary fuel to the jet |03 at higher vacuums is possible than by the provision of one such valve, and the flow of fluid may be closely regulated by the adjustment of the tension and the comparative strengths of springs and ||8 of valve |04 and the spring of valve |05, by the relative dimensions of the orifices |09 and ||5, and by the comparative resistance of diaphragms and ||-2.

As shown in Figure 3, the main metering jet |03 for the feeding of supplementary fuel into the intake manifold of the engine is similar in construction to the metering jet 53 for main fuel as hereinbefore described. However the metering jet |03 is not open to the float chamber and flow from the float chamber to the venturi' does not occur directly as with the main fuel. The main supplementary fuel jet |03 comprises a closed, generally cylindrical casing |2'4a, having an-axial, generally cylindrical bore closed at one end aby threaded cap |26. The bore |25 also receives an axially apertured threaded cap |21 having a central bore |21a and apertures |20 communicating therewith. A metering jet block |29 is disposed in the bore |25 extending radially Ithereacross and having a central metering jet formed interio-rly thereof for the passage of supplementary fuel therethrough. A cylindrical, axially bored sleeve is mounted within the bore |25 beyond the block |29 and is peripherally apertured as at |30a. An air bleed chamber |3| is defined by a dome-like cap |32 apertured to admit air to the chamber which communicates with the interior of sleeve |30 through passages |33 and apertures |30a. Thus, it may be seenvthat supplementary fuel passing through the conduits |22 and |23 (Figure 6) Will ow through the metering jets |29 and |24 into the sleeve |30 and air from chamber |3| will be admixed with the supplementary fuel passing through 'the sleeve |30 in the manner hereinbefore described.

The present invention also provides means whereby an added amount of supplementary fuel is fed to the main fuel-air stream entering the intake manifold of the engine during rapid acceleration caused by movement of the throttle controls. This additional amount of supplementary fuel is fed through an accelerating pump |34 similar to the pump 86 hereinbefore described in connection with the feeding of main fuel upon acceleration. As shown in Figure 5, the pump" |34 is positioned within the housing defined bythe sections 28 and 30 formed in the casing sections I2 and respectively.

The pump |34 comprises a pump actuating arm 40 connected through throttle links 38a and 38h to throttle lever 31 as hereinbefore described. The

. pump |34 is actuated under the same conditions as the pump 86 hereinbefore described for the feeding of main fuel upon acceleration. The pump |34 is provided with a slidable sleeve |35 having a dependent gasket |36 contacting the interior surfaces of the housing '28 and a coil spring |31 urging the sleeve |35 against the end of the actuating rod 40 by bearing against a flange |38 which is mounted on the actuating rod 42. A second coil spring |39 is compressed between the top interior surface of the housing section 30 and against the upper surface of asleeve |40cpntacting the upper surface ofthe flangey |38.- Ingrese to the pump housing is provided by passage |4| communicating with chamber 22 (Figure 4) and egress is provided throughpassage |42 communicating with nozzle 90. y

The sleeve |40, as best shown in Figure 6, Carries an arm 43 extending radially from4 the actuator arm 40 through a slot |44 formed in housing sections 28 and 30 on that side of the housing adjacent the diaphragm and spring urged valve |04i The arm |43 is formed with a depending portion |45 and a second portion |46 parallel to the arm |43. I The free end of portion |46 carries a cylindrical open-ended boss |41`vreceivillig a piston |48 urged downwardly by spring |49.-

It may be seen from Figure 6-that,upon sudden acceleration of the engine and the depression of the actuating arm 40 by movement of the throttle lever 3l,- the piston |48 will come' into contact with the upper surface of the valve |04. Upon contact of the piston with the valve, the valve |04 will be depressed-to seat the seating face ||5 in orifice ||6 cutting off` the flow of supplementary fueltherethrough. Thus, duringr'apid acceleration, the feeding of anti-detonant fuel will take place through the metering valve |05 exclusively. Following Vacceleration and during operation of the engine at high speed, the arm 40 will remain in depressed position to maintain the valve |04 in closed position. As soon as that vacuum necessary to closethe yvalve |05 has been reached, this valve will be closed by .the action of the diaphragm I I2, while the ,valve 04 remains mechanically closed by means of .the arm piston |45 to prevent the iiow of fluid through this valve. This stopping of the now through Ybothvalves at full throttle and high vacuums-results in a'substantial saving of supplementary fuel inasmuch as it is thus possible tow operate the engine at high speed where no detonation takes place without feeding any supplementary fuel to theengine.4 This permits a more sensitive setting of the valve |04 so that flow may be obtained at lower speeds where knock is more likely to occur without the necessity of feeding unwanted fuel at high speeds.- n y g It will,v of course, be understood that various details ofr construction may beY variedthrough a widerange without departing from the principles of this invention, and it is, therefore, not the purpose to limit the' patent granted hereon otherwise than necessitated ,by the scope of the appendedclaims.

I claim as my invention: l y

l. A dual carburetor comprising lcasing means providing an ,air inlet passageway and a pair of isolated fuel chambers, floats in` said chambers, intake valves controlled by said floats for controlling flow of fuel into said-chambersA from a source, spaced choke and Athrottle valves in said air passageway, a Venturi throat in said passageway between said valves, metering jets connecting said chambers with the Venturi throat to produce a mixture of air from the choke valve and fuel from the chambers, vacuum-operated valve; means regulating flow to one of said jets from one of said chambers to control the content of fluid from said one chamber in said mixture in accordance with manifold pressure of the engine, pump means operated by an opening movement of the throttle valve to feed additional fuel from both chambers toy the venturi throat to provide an additional fuel charge upon rapid acceleration of the engine and means operable A aesinet? l1 upon movementA of said throttle valve toa predetermined open position for decreasing the flow of fuel from said one of said chambers.

2. In a dual carburetor for introducing a main fuel-air mixture containing supplementary fuel into an air intake located centrally of said carburetor, a pair of fuel chambers located on opposing sides of said air intake, one of said fuel chambers being connected to a source of main fuel and the other of said fuel chambers being connected to a source of supplementary fuel, means located in said one float chamber for effecting the introduction of main fuel into said air intake in accordance with the amount of air flowing through said intake, valve means in communication with said one chamber for introducing main fuel into said intake in accordance with manifold vacuum of said engine, pump means in communication with said one chamber for introducing lan additional main fuel charge into said air intake when said engine is accelerated, additional valve means located in said other chamber for introducing supplementary fuel to said intake in accordance with intake manifold vacuum of said engine, additional pump means in communication Withsaid other chamber for introducing supplementary fuel into said air intake during rapid acceleration of said engine, and means controlled by said additional pump means for interrupting the flow of supplementary fuel through said additional valve means when said engine is operated at high speed.

3. A dual carburetor comprising a casing deiining an air inlet, a throttle valve located in said inlet, a choke valve located in said inlet, a venturi located between said valves, a reservoir for containing a body of main hydrocarbon fuel, means for introducing main fuel from said reservoir into said venturi, a second reservoir located on the other side of said air inlet for containing a body of supplementary fuel, valve means located in said second reservoir for controlling the introduction of supplementary fuel therefrom to said venturi, pump means in communication with said second reservoir. for injecting an additional charge of supplementary fuel into said Venturi upon movement of said throttle valve, and means actuated by said pump means for engagingA said valve means when said throttle is open to prevent feeding of supplementary fuel through the Valve means to said venturi during operation of said engine at full throttle and high speed.

4. In a dual carburetor for theintroduotion of main fuel and supplementary fuel into an internal combustion engine and having an air inlet with a throttle valve located therein, separate reservoirs on either side of said inlet for containing main fuel and supplementary fuel and pressure-controlled valve means located in said supplementary fuel reservoir for injecting supplementary fuel into said intake ahead of said throttle valve in accordance with the manifold pres- 12 sure of the engine, pump means for injecting an additional charge of supplementary fuel upon sudden acceleration of said engine and means for interrupting the flow of supplementary fuel from ,said reservoir during operation of the engine at Vinlet for conveying supplementary fuel under pressure from said pump chamber to said inlet upon movement of said arm linked to said throttle valve, and said flow interrupting means including an arm secured to sum pump actuator arm for movement therewith and piston means resiliently mounted on said arm for contacting said pressure-controlled valve means to close the same upon movement of said actuator arm.

5. In a dual carburetor comprising a casing defining an air inlet and an outlet adapted for connection to the intake manifold of an internal combustion engine, a venturi between said inlet and said outlet, a throttle valve between said venturi and said outlet, a plurality of fuel reservoirs supplying different fuel respectively to said venturi, valve means between one of said reservoirs and said venturi controlled by pressure at said outlet for introducing an increasing amount of fuel with increasing manifold pressure, and closure means connected to said throttle valve for closing said valve means when said throttle valve is moved to a predetermined position.

6. In a dual carburetor assembly including a plurality of fuel chambers and a throttle valve, the improvement comprising rst and second valves communicating with one of said chambers and vented to the engine intake manifold end of the carburetor, said valves being biased to open position, said first valve closing before said second valve as manifold vacuum increases, said second valve opening before said first valve as manifold vacuum decreases, and closure means connected to said throttle valve for closing said second valve at a predetermined open position of said throttle valve.

DAVID E. ANDERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Ericson r July 26, 1949

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