US3545730A

US3545730A - Fuel control and fuel feeder unit for internal combustion engines

Info

Publication number: US3545730A
Application number: US685926A
Authority: US
Inventors: Joseph A Bascle Jr
Original assignee: Associated Consultants Inc
Current assignee: Associated Consultants Inc
Priority date: 1967-11-27
Filing date: 1967-11-27
Publication date: 1970-12-08
Anticipated expiration: 1987-12-08

Description

I United States Patent [111 3,545,730

[72] inventor Joleph A- MI J 3,322,408 5/1967 Stoltman 26l/5 Baton Rouge, Louisiana 3,339,900 9/1967 De Rugeris.. 26|/50(. l)X [21] Appl. No. 685,926 3,362,694 l/l968 Gould 26l/50(. l)X

525: Primary Examiner-Tim R. Miles l Assignee Ammed Column, Inc. Attorney Wilkinson, Mawhmney and 'iiheibault Baton Rouge, Louisiana a corporation of Louisiana ABSTRACT: Two air valves, biased to closed positions, and [54] FUEL CONTROL AND FUEL FEEDER UNIT FOR automatically opened by the differential pressures of engine INTERNAL COMBUSTION ENGINES suction and throttle-controlled atmospheric air induction 12 Chin" B Dnwlnl nu. when the internal combustion engine is started in operation,

control the admission of air to two separate carburetor chan- [52] U-S-Cl- 261/46, elsI one of which deivers air to the conventional manifold 261/50 261/71 261/65 and the other of which delivers air to a fuel nozzle and the [51 1 III. Ci. F02m 7/12 resulting i -J d mixture to a supp|ementa| manifom the fuel Field ofs'al'ch 261/46 supply being controlled by at least two fuel valves so as- 23 sociated with the closing mechanism for at least one of the air valves that on opening of such. air valve the primary fuel valve [56] References cued will be proportionally opened to fully meet current suction de- UNITED STATES PATENTS mands, while the other fuel valve is subject to both accelerator 1.39 10/1921 Chase 261/46 and manual control, all contributing to a coordinated system l,935,80l li/l933 Koehly.. 26l/ (-l) by which greatly improved carburetion is achieved particu- 2,357,673 1944 Lee 261/46 larly for meeting conjoint factors of variable load and speed 2, ,801 4/1957 Du t 261/46 conditions encountered in current vehicle operation. in short, 2,828,] 16 3/ i958 Bascle, Jr. 26i/50(.1)X the disclosure is to an updated carburetion system.

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ATTORNEYS Joseph A. Boscle,Jr.

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IN V EN TOR.

I E C N s M O 1% B an A 'PATENTED DEC 8 I970 SHEET 7' OF 7 INVENTOR. Joseph A. Bascle,Jr.

E" h w M,Wmigj ATTORNEYS 1. FUEL CO TROL AND FUEL FEEDER UNI FOR INTERNAL COMBUSTION ENGINES The present invention relates to a FUEL CONTROL AND FUEL FEEDER UNIT FOR INTERNAL COMBUSTION EN- GINES and has for an object to provide improvements over my prior US. Pat. No. 2,828,116 granted Mar. 25, 1958, and for use with the carburetor inlet manifolds forming the subject matter of my prior US. Pat. No. 3,398,938, granted Aug. 27, 1968.

The primary object of the present invention is to provide and control fuel supplies to the mixing chamber of a carburetor under a plurality of controls operated to produce variable air fuel mixtures under all operating and load conditions of a vehicular or other internal combustion engine.

Another object of the invention is to provide improved means for coordinating fuelsupply to airvalve controls involving a plurality of air valves in which the ultimate mixture is delivered to an additional manifold over and/or beyond the conventional manifold, such air valve control being also operative to provide additional air. circulated to the engine through the conventional manifold.

A further object of the invention is to include, in conjunction with the plural fuel supply valves, a provision for the complete stoppage or shutoff of all fuel to the manifold and engine to avoid unnecessary dissipation of unburned fuel to atmosphere such as caused by further rotation of engine following ignition turnoff or coasting.

A still further object of the invention is to produce in one carburetor construction the desirable features of both a low speed carburetor and a power producing carburetor, to the end that the carburetor of this invention shall economically andefficiently function during city driving, and be prepared at all times to be equally responsive for extreme power production, such ascould be obtained through the use of superchargers.

With the foregoing and other objects in view, the invention will be more fully described hereinafter and will be more particularly pointed out in the claims appended hereto.

In the drawings, wherein like symbols refer to like or corresponding parts throughout the several views:

FIG. 1 is a top plan view of a FUEL CONTROL AND FUEL FEEDER UNIT FOR INTERNAL COMBUSTION EN- GINES;

FIG. 2 is a side elevational view taken from the throttle operating side and showing the'parts in the idling position;

FIG. 3 is a fragmentary side elevational view taken on the line 33 in FIG. 1;

FIG. 4 is an end elevational view taken from the left end of FIG. 1 with parts broken away and parts shown in section;

FIG. 5 is a vertical longitudinal sectional view taken on the line 5-5 in FIG. 1 and showing the closed position of the throttle, fuel and air inlet valves;

FIG. 6 is a similar view showing the open positions of the throttle, fuel and air inlet valves;

FIG. 7 is a top plan view' of the fuel-feeder unit with parts broken away and parts shown inseetion;

FIG. 8 is a vertical sectional view taken on the line 8-8 in FIG. 7;

FIG. 9 is also a vertical sectional view taken on the line 9-9 in FIG. 7; I

FIG. 10 is a vertical sectional view taken on the line l0-l0 in FIG. 1 and showing the nonoperating position of the secondary fuel control valve, which is a closed position of the valve when the engine is not in operation;

FIG. 11 is a vertical sectional view taken on the line 11-11 of FIG. 1 showing the operating position of the parts of the secondary fuel valve with thevalve in a partially open position, that is an idling position;

FIG. 12 is a vertical sectional view taken on the line 12-12 in FIG. 1 showing the operating position of the parts and the valve in the approximate full open position; and

FIG. 13 is an, elevational view showing the conventional manifold together with the auxiliary manifold and connections of the carburetor of this invention to both manifolds.

Referring more particularly tothe drawings, the invention is illustrated in a single mechanical embodiment for. purposes of illustration, which is the best formof the invention known to me at this time, 20 designates the midsection of a carburetor body, 21 the lower section and 22 the lid, the sections being appropriately connected together by any suitable means, for instance by the

bolts

23 and 24. The sections 20 and 2l are hollow and the lower section is adapted to be bolted to a conventional manifold of an internal combustion engine.

The lid is at one side provided with an elbow forming an air induction connection 25, in which is disposed a conventional throttle valve 26 mounted for rotation on a throttle shaft 27.

The midsection 20 is composed of a lower division 28 and an upper division 29, in which the lower division 28 is of substantially smaller diameter than the division 29 above: such divisions being connected by a substantially horizontal septum 30.

An annular secondary air valve 31 is mounted for vertical reciprocation within the upper division wall 29, said valve 31 having a cylindrical skirt 32 slidable up and down within the lower division wall 28' between the positions shown roughly in FIGS. 5 and 6.

Associated with the secondary air valve is a primary air valve 33 also preferably consisting of an annular flat horizontal ring partially overlapping the secondary air valve 31, and having dependent from an inner edge thereof a cylindrical skirt 34 fitted to slide up and down uponthe cylindrical wall of an air tube 35 fixedly carried at its upper end by the lid 22, and occupying a substantially central position with respect to the

skirts

32 and 34.

The

skirts

32 and 34 are of differential diameters in order to provide an annular space therebetween for receiving air from the air induction connection 25 and circulating such air downwardly to the conventional manifold. The air tube 35 is provided at its upperendwith slots 36 communicating with an air space 37 beneath the lid 22. The air space 37.is at all times in open communication with the air induction elbow 25 through knurled circular surface against which the primary air valve abuts in its'uppermost position so that immediately on opening to any extent of the throttle valve 26 atmospheric air will be supplied to the air space 37.

The lower portion of the tube 35 is provided with a venturi section 38,, within which projects a fuel nozzle 39 also mounted in and projecting down from the lid 22 and communicating with an internal fuel passage 40. The lower end of the tube 35 is connected by an elbow or other connection 41 with a restricted high velocity distributing manifold 42, such as the manifold identified in my prior U.S. Pat. application, Ser. No.674,218 at 24, 25.

A vacuum pipe 43 is connected through the horizontal septum 30 with the space beneath the secondary air valve 31, connecting at its lower end with the internal chamber of the lower carburetor body section 21 which latter chamber is in communication directly with the conventional manifold and therefore is subject to vacuum conditions during operation of the engine, which vacuum conditions are transferred by the pipe or pipes 43 with the chamber below the secondary air valve 31 whereby the vacuum pull of the engine will operate to open the secondary air valve 31 from the closed position of FIG. 5 to the open position of FIG. 6.

As shown more particularly in FIGS. 5 and 6, the fuel passage 40 in the lid 22 connects at its upper end with the lower end of a cross passage 44 in the lower end portion of a secondary valve guide body 45 having at its lower end beyond the cross passage a recess 46 in which is removably fitted a jet 48 having a port therethrough of desired selected cross section. The port of the jet 48 opens directly into the hollow valve guide body 45 at one end and into a fuel passage 47 at the other end, The passage 47 is in the fuel-feeder upper body 64, shown more particularly in FIG. 8.

This fuel passage 47 communicates by one or more openings 49 with a diaphragm chamber 50 having a movable .flexible diaphragm 51 actuated by a plunger 52 from a rocker -arm 53 (FIGS. 5 and 6) on a rocker shaft 54, the actuation of which will be later described.

The primary fuel needle valve 55 is urged by a spring 56 against the diaphragm 51 and through a jet 57 removably mounted in the fuel feeder upper body 64.

As shown in FIG. 7 fuel is introduced through a fuel inlet 58 to a filtering device 59 and after passing through the same, the filtered fuel is introduced through a port 60 to the valve chamber 61. The needle valve 55 includes a flat-sided section 62 which cooperates with the cylindrical valve chamber 61 to provide passages for the filtered fuel into the chamber 61 and eventually through the ported jet 57 and into the diaphragm chamber 50.

As more particularly shown in FIGS. 7 and 9, an adjustable pressure control is provided in the fuel-feeder upper body 64 for recirculating excess fuel back to source. This control involves a valve 70 yieldably urged by a coil spring 71 onto a valve seat 72. The tension of the spring 71 may be adjusted by a hollow screw 73 partially receiving spring 71 and threaded adjustably into a threaded opening in the upper fuel-feeder body 64. As shown more particularly in FIG. 7, a fuel overflow outlet 74 enters laterally into the overflow valve spring chamber and connects with a suitable return pipe for recirculating the excess fuel into the fuel tank or source. A locknut 75 may be threaded on the screwhead 73 to lock the adjustment after the tension of the spring 71 has been adjusted by suitable rotation of the screw.

As shown more particularly in FIGS. and 11, the secondary fuel valve 65 is preferably and relatively of long tapered form coming to a substantial point at its free end and at its outer larger end adjoins a cylindrical section 76 which is adapted to fit snugly into asimilar cylindrical section 77 of the jet 48 in the closed position of this secondary fuel control needle valve 65.

The stem 66 at its outer end is provided with a threaded section 78 adapted to receive locknuts 79 which are adjustable on this threaded section and which constitute together a stop adapted to abut the closed outer end of the barrel 69 which slides freely longitudinally over the secondary valve guide body 45.

As best shown in FIGS. 5 and 6, a coil spring 80 is wound about the stem 66 abutting the internal wall closed end 68 of the barrel 69 and having its forward end abutted against a retaining lock-washer 8-1.

The fuel control valve 65 is movable to open and closed positions through a sliding movement of the barrel 69 on the stem 66. When the valve 65 is in the partially open position shown in FIG. 11, the spring 80 is in expanded condition driving the locknuts 79 against the end wall 68 of the barrel 69. This will permit an opening movement of the valve by an outward sliding movement of the barrel 69 in which the end wall 68 of the barrel impinges and carries outwardly the locknuts 79 and the stem 66 which in entrainedtherewith.

As best shown in FIG. 11, a ground shoulder 82 is formed on the lower end of the stem 66 greater in diameter than the cylindrical section 76. This ground shoulder 82 is adapted, in the final closed position of this valve, to seat against or mate with a companion ground end wall 83 of the jet 48 to form a leak-proof seal completely cutting off all flow of fuel into the fuel line 40. In moving to this closed position the stem 66 will be arrested in motion when the ground shoulder 82 encounters the end ground wall 83. As the stem 66 becomes stationary, so does the retaining lock washer 81 which is affixed to the stem 66. Therefore, further movement of the barrel 69 in the direction of closing movement will cause its outer end wall 68 to compress the spring 80. This provides a cushioned final seating between the valve and the jet 48.

An air bleed line 63 is connected between the air induction elbow and the cross passage 44 in the fuel-feeder upper body 64 as shown in FIG. 6.

As shown more particularly in FIGS. 10, 11 and 12, the secondary fuel control needle valve 65 cooperates with the jet 48 to effect secondary control of the fuel to the fuel passage 40 and eventually to the carburetor fuel nozzle 39. This secondary fuel control valve 65 is carried by a stem 66 slidably working in a secondary valve guide body 45, which at its outer end slides through a closed end 68 of a barrel 69 slidably fitted over the stationary secondary valve guide body 45.

Referring more particularly to FIGSQ10 and 12 in connection with FIG. 1, a pair of links 84 are pivoted at 85 to the barrel 69, one link at each side of the barrel 69 as shown in FIG. 1. These links are in turn pivoted at 86 to the upper ends of rocker arms 87 which at their lower ends are keyed to a shaft 88 supported for rotation in bearings 89 erected upon the lid 22 as shown more particularly in FIG. 2.

At the outer ends of the shaft 88,

other rocker arms

90 and 91 are also affixed or keyed to the same shaft 88. The

latter rocker arms

90 and 91 are disposed outwardly of the bearings 89 and have pivoted thereto, as indicated at 92 and 93,

links

94 and 95. At their opposite ends the

links

94 and 95 are pivoted at 96 and 97 to similar rotatable triangularly shaped

plates

98 and 99 which are affixed to the throttle shaft 27 at opposite ends thereof.

In the plan view of FIG. 1 the plate 98 has a forward extension 100 which partially overlaps the plate 98'and forms a convenient attachment to an accelerator control member 101, the later latter detailed in FIGS. 10 and 12.

FIGS. 10 and 12 illustrate substantially opposite positions of rotary movement of the combined

plates

98 and 100 in the closed and substantially wide open positions of the throttle valve 26.

In FIG. 10 the closedposition of the throttle valve 26 determines, through the mechanical linkage described, the fully closed position of the secondary fuel valve 65, while the positions of these parts in FIG. (FIGS. demonstrate that on full open throttle the secondary fuel actuation of 65 will also have been moved to full open position.

Customary throttle-check-

stops

102 and 103 are provided to adjustably arrest the

parts

98 and 100 in opposite positions of their conjoint movement. I i

In FIG. 11, which shows the operating mechanism of an auxiliary control for the secondary fuel valve 65 placed at the opposite side of the carburetor, the plate 99 carries an adjusting stop 104 positioned in the path of movement of a cam lever 105 freely pivoting about a center 106 within the limit prescribed by a limit stop 107. The movement of the cam lever is effected by a push-pull control cable 108. The cam lever presents a cam surface 109 to the adjustable stop 104.

Referring more particularly to FIG. 4, push-pull rods 110 are affixed to the secondary air valve 31 to move up and down through guides lll made through lid 22. At their upper ends these push-pull rods 110 areconnected by a crossbar 112 lifted to the raised position of FIG. 4 by a spring member 113 to maintain both

air valves

31 and 33 in a normally closed position. The crossbar 112 carries a block 114. A pin 115 projects laterally from the block 114 and extends through a slot 116 in an arm 117 affixed to the shaft 54 as shown in FIG. 2. Thus, when the crossbar'112 descends incident to opening of the secondary air valve 31 the shaft 54 will be rotated, causing the rocker arm 53 to raise the plunger 52 and unseat the primary fuel valve, all as seen in FIG. 5.

The spring member 113, as shown in FIG. 1, is a looped center portion of a resilient wire coiled about the shaft 88 in two

helices

118 and 119 with the free ends 120 and 121 looped about

rollers

122 and 123 journaled to rotate respectively about the triangularly shaped

plates

98 and 99 so that these rollers partake of the movement of

such plates

98 and 99, in consequence of which the tensions ofthe

helices

118 and 119 are relaxed for the purpose of reducing the elastic tension effective against the crossbar 112 at a time when that crossbar 112 is being lowered so as not to interfere with the free descent of the secondary air valve 31 on opening movement of the throttle valve.

In operation, with the throttle 26 closed as shown in FIG. 5, the primary and

secondary air valves

33 and 31 are also closed by the lifting force of spring loop 1 13 applied beneath crossbar 112 which are lifts crossbar 112 and connected push-pull rods 110 which are attached at their lower ends to the secondary air valve 31. As the primary air valve 33 overlaps and nected tojthe convention rides upon the secondary valve the valves will assume the closed positions of F 0.5 when the engine is not running.

When the ignition isjturned on, generating vacuum or negativepress'ure in the cylinders and manifolds, and the throttle valve 26 Eopened,eve n to'an idling position, air will enter at 25 with positivev pressurjef to' which the upper surfaces of the

air valves

31 and 33 will lie-subjected.-

The fully open position ornie primary valve 33 is reached when the lower endj ofits skirt 34. encounters stop 124, at which time secondary valvefil continues to descend until its packing box 125;contacts' the septum 30in which position a gap between the valves FlG. filopens-the secondary channel to air induction and allowsthrottle-controlled air unmixed with fuel to pass into the conventional manifold 126.

Air passes at the Same time over the upper surface of the open primary air valve'33 bywhich it is directed to slots 36 and into the tube 35 where it descends and picks up fuel from the nozzle, :the resulting fuel-air admixture being drawn into the secondary or. auxiliary-manifold 127 through cross channels42L-"j I i I As shown in FlG. l3, the secondary manifold 127 is cona l manifold 126 as per my copending application aforesaid. v

The. fuel-air mixture :moves at relatively high velocity through thenarrowercross section of the secondary manifold and is deliveredto the'conventionalmanifold l26'at cylinder lociwh'ere the fuel' air mixture is leaned, as desired, by admixture with the additional air being delivered through the conventional manifold. g 1 v Now, when the Secondary air valve 31 initially moves down it will carry with it thepush-pull rods 110 and the crossbar 112 against the a'ctionof its spring 113 and thru the

train

114, 115, 116, 11154.53 and sz'wiiljo en the primary fuel valve 55.

Now the throttle v'al've fzeiis operated'manually by accelerator or cable acting iinthe-'manner'hereinabove described through the trains of partsillustrated in FIGS. and 12 for the accelerator and 5108.3 and 11 for the manual cable, and due to the entrainment of-parts shown in these FIGS. the secondary fuel valve will be opened proportionately to the degree of port area opened by the throttle valve.

FIGS. 10 and 12 show'the" two positions of the parts concerned with accelerator actuation; while FIGS. 3 and 11 illustrate the manual actuation through the instrument panel button and pull-rod 108. FIG S .'3 and 11 are taken from relatively opposite sides of the pull-rod actuation device. I

' Referring to FIGS. 10,11 and 12, the reference numeral 108 points to the knobb'ed'e'nd' of the control'cable which is located on the instrument panel of a stationary or vehicular machine. The other end of the cable is attached to the actuating lever'105 back of the dash instrument panel and by pulling out the knob of cable 108 a complete stoppage of flow of fuel into the manifold iseffected, when air pollution control is desirable; Examples, .suchas concomitantly with ignition turnoff and/or -on prolonged deceleration such as going down fuel delivered to thej channel 40, while the cylindrical section 76 snugly fits into the-cylindrical port section 77 so as to' Although I havedisclosed herein'the best form of invention known to me at this time I reserve the right to all such modif cations and changes as may come within thescope of the following claims: 1 1 Y I claim: a 1

1. in a fuel preparation system for internal combustion engines, a carburetor having primary and secondary air channels therethrough and a throttle-controlled air induction to the channels, a fuel nozzle in the primary channel, a valve seat between the air induction and primary channel, a primary air valve movable to and from the valve seat, a secondary air valve lappingthe primary air valve on the side away from the seat, means. biasing the secondary air valve to a closed position against the primary air valve and by lapped entrainment biasing the primary air valve toaclosed position against the valve seat, means for arresting opening movement of the primary air valve to less than the opening movement of the secondary air valve to permitopening of the secondary valve and admission of throttle-controlled induction air to the secondary air channel, a primary fuel metering valvein communication with a source of fuel supply, a secondary fuel metering valve in communication with the primary fuel valve and with said fuel nozzle, primary fuel metering .valve opening means connected with the biasingmeans for opening the primary fuel metering valvein proportion to the-movement of the secondary air valve toward open position, and means for opening and closing the secondary fuel valve in proportion to opening and closing movements of the throttle valve.

2. In a fuel preparation system for internal combustion engines, as claimed in claim 1, further comprising an auxiliary means to shutoff fuel beyond the range of both primary and secondary fuel metering valves. n

3. In afuel preparation system for internal combustion engines as claimed in claim 1 further comprising a seat against which the primary air valve abuts in its uppermost position, an air chamber circumscribed-within the seat and opening into the fuel nozzle channel, said seat having air passages therethrough for, admitting throttle-controlled air to the chamber and to'the upper surface of the primary air valve without regard to the open or closed position of the primary air valve.

' 4. In a fuel preparation system for internal combustion engines as claimed in claim 3 further comprising stop means for the primary, and secondary air valves for arresting downward movement ofthe primary before stoppage of thesecondary air valve .to open a'gap between the air valves leading to the secondary air channel, means connecting the secondary pure air channel with the conventional manifold, and a second air fuel mixture manifold connected to the channel in which the fuel nozzle is located and to the conventional manifold adjacent the cylinders of the engine.

5. in a fuel preparation system for internal combustion engines as claimed in claim 1 in which said biasing means includes a vertically movable member, and connections between the vertically movable member and the primary fuel valve for opening the primary fuel valve progressively in proportion to the opening of the secondary air valve.

completely shutoff the supply of fuel to the channel 40.

Finally, when'the ground shoulder 82 seats against the ground end wall 83 a tight seal is effected completely sealing off any 1 fuel to the channel 40'and to the carburetor. Such closing I together of the twoground. '

walls

82 and 83, occurring afterthe fuel has passed both'metering valves, thereby becomesa 1 s 6. In a fuel preparation system for internal combustion engines as claimed in claim 5 in which the primary fuel valve is a tapering needle slidable through a jet seat and biased to a closed position, a diaphragm chamber in controlled communication through the needle valve and jet seat with a source of fuel supply, a flexible diaphragm in the chamber in operative position relatively to the needle valve to adjust the tapering needle valve relatively to its jet seat, and connections between the diaphragm and the vertically movable member for shifting the diaphragm to open the primary fuel valve proportionately :to the opening of the secondary air valve.

- 7. In a fuel preparation system for internal combustion enfinal actionto prevent fuel dripping into themanifold or engine. in other words, these two ground surfaces, when closed together,.provide an auxiliary means to shut off fuel beyond the range of bothprimary and secondary fuel metering valves.

gines as claimed in claim 1, in which said biasing means at least in part includes a resilient member having connection to the last named means so that in proportion to the opening of the throttle valve the resilient pressure of said resilient 8.- In a fuel preparation system for internal combustion engines as claimed in claim 1 in which said secondary fuel metering valve comprises a ported jet having a substantially cylindrical section in the fuel line from the primary fuel metering valve, a tapering needle valve slidable through the port to enlarge or diminish the port area, a substantially cylindrical section of the valve at the base of the tapering needle of a diameter substantially mating with the cylindrical section of the jet port and adapted to seat therein in the fully closed position of the secondary fuel metering valve 9. ln a fuel preparation system for internal combustion engines as claimed in claim 8 in which said last-mentioned valve has an outstanding shoulder adjoining the cylindrical section adapted to abut the adjacent end of the jet in the fullyvclosed position of said secondary fuel metering valve.

10. In a fuel preparation system for internal combustion engines as claimed in claim 1, in which said last-named means comprises a stem carrying the secondary fuel valve, a hollow open ended guide body affixed to the carburetor in which said stem is slidable back and forth to open and close its valve, a barrel slidably mounted on said guide body having a closed end wall through which the outer end of said stem slidably fits, stop means adjustably affixed to the end of the stem projecting beyond said closed end wall of the barrel,.a spring retaining member adjustably affixed to the stern within the barrel and in spaced relation to the closed end wall of the barrel, and a coil spring surrounding the stem having its ends abutted against the internal face of the closed end wall of the barrel and against said retaining member.

11. In a fuel preparation system for internal combustion engines as claimed in claim 1 further comprising an air bleed line connected at one end to the air induction outwardly of the throttle control and at the other end to the secondary fuel metering valve to be controlled thereby.

12. In a fuel preparation system for internal combustion engines as claimed in claim 1 in which said biasing means comprises push-pull rods attached to the secondary air valve slidable through the lid of the carburetor, a cross member connecting the rods above the lid, a rock shaft mounted on the lid ad jacent the crossmember, spring helices coiled about the shaft and having a bowed central portion extending beneath said crossmember and exerting lifting pressure thereon, free ends of the helices engaging and movable with said last named means.