US3210055A

US3210055A - Carburetor

Info

Publication number: US3210055A
Application number: US122462A
Authority: US
Inventors: Warren G Kingsley
Original assignee: Bendix Corp
Current assignee: Bendix Corp
Priority date: 1961-07-07
Filing date: 1961-07-07
Publication date: 1965-10-05
Anticipated expiration: 1982-10-05
Also published as: GB1011151A; DE1426138B1

Description

Oct. 5, 1965 w. s. KINGSLEY 3,210,055

CARBURETOR Filed July 7. 1961 4 Sheets-Sheet 2 7 T 76 a 0 IV? 85 M gggglL r "hell? Z W mzgyrozz.

ATTORNEY Oct. 5, 1965 w. G. KINGSLEY GARBURETOR 4Sheets-Sheet 3 Filed July 7. 1961 WI TNESS:

Em $73M;

ATTORNEY Oct. 5, 1965 w. G. KINGSLEY 3,210,055

CARBURETOR Filed July 7. 1961 4 Sheets-Sheet 4 INV EN TOR.

ATTORNEY United States Patent 3,210,055 CARBURETOR Warren G. Kingsley, Watkins Glen, N.Y., assrgnon to The Bendix Corporation, Elmira, N.Y., a corporation of Delaware Filed July 7, 1961, Ser. No. 122,462 9 Claims. (Cl. 261-39) The present invention relates to an improvement in a carburetor for an internal combustion engine and in general relates to an improvement in the air valve type of carburetor. More particularly, the invention relates to means for providing an enriched fuel-air mixture during predetermined periods of engine operation.

An air valve carburetor may include either a piston, poppet, butterfly, etc. type of valve that is responsive to air fiow and which is commonly referred to as an air valve. In the case of a piston type air valve the piston is partially mounted in the body and a compartmentized chamber for reciprocal movement in the mixture passage to provide an approximately constant air velocity over fuel metering means. A tapered needle carried by the piston projects into a fuel orifice disposed in a bridge portion of a contoured restriction in the mixture passage to provide the fuel metering means. Posterior of the contoured restriction, a throttle valve controls the introduction of the fuel-air mixture to the engine manifolding. Piston movement to vary the air flow responsive to throttle valve movements results from the pressure differentials existing between the pressure in a portion of the mixture passage and a reference pressure usually atmospheric. The piston thus serves to vary the air flow in the mixture passage so as to maintain an approximately constant air velocity and a substantially constant vacuum between the air valve, the bridge and the fuel metering means. The vacuum pressure existing in the mixture passage between the bridge and throttle valve is communicated to the compartmentized chamber and will cause piston movements so as to vary the air flow and maintain the value of vacuum exerted on the fuel metering means at a substantially constant value. Since the needle valve is connected to the piston, any movement of the piston will necessarily vary the needle-orifice restricting characteristics by varying the effective orifice area and allowing a greater or lesser amount of fuel to be atomized.

Air valve carburetor construction, asheretofore used or proposed, has one very definite limitation in that because of the use of the described piston-needle structure, it is impossible to enrich the fuel-air mixture by restricting the air flow without concomitantly restricting the fuel metering effect. It is, therefore, a primary object of the present invention to provide fuel enrichment means which overcomes the undesirable enrichment characteristics and limitations in the air valve carburetor.

It is the object of the present invention to provide an enrichment device for carburetors which is simple in construction, positive as well as efiicient and reliable in operation, and inexpensive to manufacture and fabricate.

It is an object of the present invention to provide an enrichment device for air valve carburetors.

It is another object of the present invention to provide an enrichment device for air valve carburetors which restricts the air flow between the air valve and the bridge of the contoured restriction in the mixture passage.

It is still another object of the present invention to provide an enrichment device which, during engine starting operation, will sequential-1y reduce the carburetor air flow and decrease the restriction in the fuel metering means to thereby enrich the fuel-air mixture supplied to the engine.

3,213,055 Patented Oct. 5, 1965 "ice It isa further object :ofthe present invention to provide a device which, during wideeopen throttle operation, will reduce the carburetor airflow-so as to obtain anincreased vacuum eifectand a greater. fuel flow from the metering orifice thus enriching the'fuel-airmixture supplied to the engine.

It is afurthe-r object of the presentinvention to provide 'a contoured shaft .positioned transversely of a carburetor mixture passage adapted idur'ingv normal'carburetoroperation not to alter the air flow'characteristics of the carburetor but adapted to be rotated during predetermined periods of engine operation1so as to vary thecarburetor air flowcharacteristicsandreduce the air flow.

It is a further object of the present invention to provide a contoured shaft positioned transversely :ofan air valve carburetor mixture passage which is adapted to'be rotated to sequentiallyreduce the air-flow between the air valve and apassage restriction .and to .displace the air valve relative to the restriction so as to lessen the fuel metering effect.

"It isfurtherobject of the presentinvention to provide an enrichment device for'airvalve carburetors which is motivated to its operative position by means responsive to engine temperatures.

It isa further object of the present invention to provide an enrichment device for air valve carburetors which is motivated to its operative position by means responsive to predetermined engine .pressures.

It is a further object of the present invention to provide an enrichment device for air valve carburetors which is motivated to its operative position by a combination thermostatically actuated member and a vacuum motor.

The invention further resides in certain novel features of construction, and combinations and arrangements of parts, and further objects and advantages thereof will be apparent to those skilled in the art to Whichit pertains from the followingdescription of the preferred .iernbodiments thereof described with reference to the accompanying drawings in which similar reference characters represent correspondingparts throughout the several views, and in which:

FIGURE 1 is a longitudinal sectional view taken on the plane of line 11 of FIGURE 2 illustrating an air valve carburetor embodying the present invention and depicting the enrichment means inan inoperative position;

FIGURE 2-is anend elevation, partly broken away, of

anairvalvecarburetor embodying the present invention;

FIGURE 3 is a bottom view, partly broken away and in section, illustrating an air valve carburetor embodying the present invention;

FIGURE'4'is .a fragmentary detail perspective view, partly broken away and in section, illustrating the mixture passage contoured restriction, the contoured enrichment member and the air valve as they operatively combine to provide starting enrichment;

FIGURE 5 is a fragmentary view illustrating a thermostat member and a vacuum motor in combination providing actuating means for a'contoured enrichment shaft;

FIGURE 6 is a fragmentary view illustrating the position of the contoured enrichment shaft during normal carburetor operation;

FIGURE 7 isa fragmentary view-similiar to FIGURE 6 illustrating the contouredenrichment shaft in its maximum enriching position;

FIGURE 8 is aview: similar toFIGURES illustrating motivating meansfor enriching the fuel-airimixture when the engine operates 'at low manifold vacuum;

FIGURE 9 is a schematic view illustrating an embodi- 11161111 for motivating the enrichment device; and

FIGURE 10 is a schematic view illustrating still another embodiment for motivating the enrichment device.

Referring now to the drawings and more particularly FIGURE 1, there is illustrated an air valve carburetor generally designated 11 consisting of a body 12, a cover assembly 13, and a fuel chamber 14. A mixture passage 16 providing at its extremities an air intake 17 and a mixture outlet 18 is formed in the body 12. There is provided intermediate the passage extremities, a contoured restriction 19 having inclined anterior and

posterior approaches

21 and 22, respectively, separated by a substantially flat rectangular median portion 23 commonly referred to as a bridge. The contoured restriction 19 traverses only a segment of the mixture passage 16 with the bridge portion 23 being substantially parallel to and spaced from the axis of the passage. A throttle valve 24 in the mixture passage adjacent the outlet extremity 18 is supported on the throttle shaft 26 jonrnalled in the body to control the introduction of the fuel-air mixture to the engine manifolding (not shown). A throttle return spring 27 (FIGURE 3) anchored to one extremity of the throttle shaft tends to maintain the throttle valve in a closed position while linkage members generally designated 28 operable by the engine operator control and limit the throttle valve opening and closing movements.

The fuel chamber 14 depends from the body 12. Fuel is supplied to the fuel chamber through the inlet 29 (FIG- URE 3) and is controlled in a normal manner by a float actuated valve (not shown). Supported in a cylindrical cavity 31 formed as a part of the body immediately below the bridge 23 is the fuel jet assembly generally indicated as 32. The jet assembly extends into the fuel chamber 14 and major portions of the assembly are surrounded by fuel.

The jet assembly 32 consists of a bushing 33 extending upwardly through an aperture 34 centrally disposed in the bridge and opening into the mixture passage. A bushing retaining screw 36 is threadedly received in the cylinder 31 to maintain the bushing in contact with the under side of thebridge. The bushing retaining screw 36 extends through an appropriately located opening 37 formed in the bottom of the fuel chamber 14 with an O ring 38 providing a sealing means therebetween. A tubular orifice member 39 slidably positioned in the bushing 33 extends to the surface of the bridge to provide a metering orifice or jet. The metering orifice is maintained in a proper positional relationship relative to the bridge surface by an orifice adjusting screw 41 threadedly received in the bushing retaining screw and a spring 42 compressively confined between a flange 43 on the orifice member 39 and a recess 44 formed in the bushing 33.

Fuel from the chamber 14 will flow through openings 46 in the bushing retainer 36, openings 47 in the orifice adjusting screw 41 and thence through the tubular orifice member 39 to the jet at the bridge in the mixture passage. Metering of the fuel flow from the orifice will hereinafter be more fully described. Air entrapped in the jet assembly 32 is vented through openings 48 in the bushing retainer 36 to the space 49 between the bushing 33, the bushing retainer 36 and the cylinder 31 and thence to an opening 51 communicating with the fuel chamber above its normal fuel level. In this manner vapor lock within the jet asembly is effectively eliminated. A plug 52 closes the exterior opening of the bushing retaining screw 36.

Formed as a part of the body 12 and opening upwardly from the mixture passage 16 is an inverted frustoconical structure 53 which combines with the cover assembly 13 to define a compartmentized chamber generally designated as 54. Slidably supported within the chamber 54 and the mixture passage 16 is a piston 56 commonly referred to as the air valve. The piston slidably engages in the opening 57 between the mixture passage and the conical structure. The opening 57 is juxtaposed above the bridge 23. A flexible diaphragm 58 at its inner periphery is clamped between the piston 56 and a diaphragm retaining washer 59. The outer periphery of A, the diaphragm is clamped between the

mating flanges

61 and 62 of the cover assembly 13 and the conical structure 53, respectively, thus dividing the chamber 54 into a suction chamber 63 and a reference pressure ohamber 64.

A piston shaft 66 press fitted into the piston extends upwardly through the piston cavity 67 into sliding engagement with the bushing 68 and guide member 69 formed in the ribbed cover 13 to accurately guide the piston movements toward and away from the bridge. A light piston compression spring 71 confined between the cover 13 and the bottom wall of the piston cavity 67 urges the piston toward the bridge 23. The pressure drop created by the air flow between the bridge and the base of the piston is communicated to the suction chamber 63 by openings 72 formed in the base of the piston; thus the pressure existing in the mixture passage 16 between the throttle valve 24 and the contoured restriction 19 is communicated via the openings 72 and the piston cavity 67 to the suction chamber 63. A reference pressure, usually atmospheric pressure, is communicated to the reference chamber 64 by a passage 73. This passage in the present embodiment is vented to the air entrance through the air filter means (not shown) to prevent the ingress of undesirable foreign matter. The passage 73 may if desired be vented directly to the atmosphere, or into the air intake passage 17, or alternatively the passage may comprise a plurality of channels in combination communicating with two or more of the following, the air intake 17, the atmosphere, the mixture passage 16 adjacent the mixture outlet 18 or a source of manifold vacuum.

Operatively connected to the piston 56 is a tapered metering needle 74 which projects into the fuel orifice 39 to regulate the effective orifice area subject to the substantially constant vacuum created by the constant air velocity to restrict the fuel flow therefrom. The needle is secured to the piston by any convenient means such as a set screw 76.

Means in the form of punctiform detents 77, best illustrated in FIGURES 2 and 3, are provided on the bottom face of the piston in a position to contact the bridge and establish a minimal spatial Separation between the piston 56 and the bridge 23. The function served by the detent 77 could, of course, be accomplished by adjusting set screws (not shown) positioned in the body or conical structure adapted to engage the piston during its movement to establish the lower limits of piston travel.

Fuel enrichment means in the form of a contoured shaft 78, hereinafter for convenience referred to as the choke shaft, is provided to enrich the fuel-air mixture during predetermined periods of engine operation. The shaft 78 is journalled adjacent its extremities in the body 12 and traverses the mixture passage substantially normal or crosswise to the air flow. The shaft intermediate its extremities is contoured as at 79. The contour in this embodiment is segmentally shaped and offset from the shaft axis. During normal carburetor operation, the contoured portion 79 is positioned in a transverse void 81 formed in the incline 21. The normal non-enriching position of the contoured choke shaft relative to the contoured restriction 19 is best illustrated in FIGURE 6 while FIGURE 7 illustrates the contoured choke shaft rotated to its maximum enriching position. It will be apparent that during normal operation, illustrated in FIGURE 1, the shaft contour 79 is adapted to complement the inclined surfaces adjacent the void 81 causing the contoured restriction 19 to be substantially symmetrical. During enrichment operations, the contoured shaft is adapted to variably change the cross section of the restriction 19 causing it to assume an asymmetrical configuration. Enrichment by rotation of the choke shaft in effect reduces the air flow between the piston 56 and the bridge 23.

When the piston 56 is fully actuatedv toward and in contact with the bridge 23, as at the time of starting,

the spatial separation therebetween will be at its minimum as determined by the detents 77. Initial rotation of the shaft will cause the contour 79 to move toward the base of the piston thereby progressively reducing the air flow passage. Continued rotation of the choke shaft'after the air flow passage has been closed will cause the contour 79 to abut the piston base and urge the piston away from the bridge while continuing to close off the air passage. Movement of the piston introduced by the shaft will cause the metering needle to be withdrawn from the orifice thus decreasing the fuel metering effect or, in other words, it will increase the'eifective area of the jet. The reduction in metering effect during enrichment is not accompanied by an increased air flow but, rather, the air flow is substantially decreased and the amount of fuel atomized is increased thereby providing a temporarily enriched mixture.

Enrichment at wide-open throttle can also be accomplished by means of the contoured choke shaft 79. At

wide-open throttle and during maximum r.p.m. or predetermined r.p.m. operations the piston will be drawn away from the bridge to the maximum amount allowable to provide the maximum air flow and the needle and orifice restriction will be reduced to its minimum providing the greatest amount of effective jet area. Rotating the shaft contour 79 willreduce the air flow passage While the fuel metering means remain unaffected thus an enriched fuel-air mixture is readily obtainable to supplement normal wide-open throttle at maximum or predetermined r.p.m. operation. In effect, more fuel is atomized into less air. At Wide-open throttle below the maximum or predetermined r.p.m. operations the air valve will assume various positions less than the full open or up position. Rotating the shaft contour 79 will act to reduce the air flow between the air valve and bridge 19 while the fuel metering means remain at least temporarily unaffected thus causing an enriched fuel-air mixture.

The contoured shaft 78 can be actuated or motivated in several ways. Linkage, generally indicated as 82, may be manually actuated by the engine'operator through a Bowden wire connect-ion (not shown). This linkage can be mechanically coupled to the throttle linkage 28 so as to provide a predetermined throttle setting prior to enrichment. A choke return spring'83 will urge the contoured choke shaft to its non-enriching position. Mechanical linkages well known to those skilled in this art will'serve the express purpose without requiring the exercise of inventive ingenuity.

The enrichment means may be automatically controlled. In FIGURE 5 there is illustrated an embodiment of the invention for obtaining cold starting enrichment wherein the choke shaft 178 having a contoured portion 179, has an extremity 181 extending into a housing 182. A thermostatically actuated member 183 in the form of a bimetallic coil spring is anchored to the shaft extremity 181 and to a fixed member in a fashion well known in this art. The coil 183 is adapted when cold to actuate 'the choke shaft 178 to an enriching position and when heated to actuate the shaft to a non-enriching position. Heat generated by the engine is communicated to the housing 182 in any convenient manner to cause the coil to be actuated responsive to changes in engine temperatures. A vacuum motor in the form of a piston 184, slidably mounted in a portion of the housing 182 and connected to a source of vacuum, is operably connected to the shaft extremity 181 to vary and control the enriching position of the shaft dependent upon varying engine operating conditions. While the embodiment of FIGURE 5 has been described and illustrated as being a parallel connection, i.e., the bimetallic coil and vacuum motor are connected to the choke shaft structurally independent of each other, it will be apparent to those skilled in the art that a series connection would work equally as well, i.e., that the'bimetallic coil is anchored to the shaft at one end and the other end is connected to the vacuum motor.

In FIGURE 9 there is diagrammatically illustrated an embodiment for automatically enriching the mixture. A bimetallic coil spring 301 is anchored at one extremity to a stationary member and has its free extremity adapted to cooperate with a lever 302 secured to a choke shaft 303. Biasing means such as a spring 304 associated with the lever cause the choke to be rotated in a counterclockwise direction to an enriching position. Means generally designated as 306, consisting of either a vacuum motor or solenoid, are operably connected to the lever 302 and offset the biasing action of the spring 304 for the purposes well understood in this art. As the engine attains proper operating temperatures the free extremity of the bimetallic spring 301 will engage the lever 302 and urge the choke 303 in a clockwise direction to its non-enriching position indicated in broken lines.

In FIGURE 10 there is diagrammatically illustrated still another embodiment for automatically enriching the mixture. A lever 321 is fixedly secured to a choke shaft 322. A bimetallic spring 323, here illustrated as a hairpin spring has its extremities operably connected to the lever 321 and a connecting member 324 of means generally designated as 326, consisting of either a vacuum motor or solenoid. When the utilizing engine is started, the elements will be positioned as is indicated by the solid lines. After the engine has been initially actuated the means 326 will cause the bimetallic spring 323 and lever to assume the position illustrated in broken lines so as to prevent over-enrichment. As the engine attains its operating temperature the bimetallic spring 323 will contract causing the lever 321 to assume the position illustrated in dash lines which position is the choke nonenriching position.

In FIGURE 8 there is illustrated an embodiment of the invention wherein the contoured shaft 278 is actuated to provide an enriched mixture at wide-open throttle operation. A cylindrical housing 281 formed as a part on or of the body 12 supports a piston 282 adapted for reciprocal movement toward and away from a cylinder end wall 283. Passage means 284 communicate a source of engine manifold vacuum to the cylindrical housing adjacent its end Wall 283. A metering restriction 286 may be provided. Rod means 287 connect the piston to a lever 288 fixedly secured to the extremity of the choke shaft 278 to translate the reciprocal piston movements into rotarial movements of the shaft 278. A spring 289 encompassing the shaft extremity biases the shaft lever to the enriched position illustrated in broken lines and acts against the force of the manifold vacuum. Stop means 291 and 292 limit shaft rotation. Manifold vacuum communicated to the housing 281 normally exerts sufiicient force on the piston to draw it toward the end wall 283 and maintain the shaft in a normal nonenriching position. At wide-open throttle the manifold vacuum will be insufiicient to overcome the force of the spring 289 and the shaft will be rotated to its enriching position. Alsov at the initiation of starting operations the shaft will assume an enriching position. In the enriching position the shaft will reduce the air flow between the bridge and the air valve. The metering needle and orifice at wide-open operation will assume a predetermined relationship. When the air How is reduced by the choke shaft, the needle-orifice relationship will not be immediately changed and thus the reduced air flow unaccompanied by any change in the fuel metering effect will resultingly provide an enriched fuel-air mixture over and above that obtainable at normal wide open throttle operation.

In operation, variations in the degree of throttle valve opening between fully closed and wide open will vary the mixture passage pressures existing between the bridge 23 and the throttle valve 24. The passage pressures are communicated to the upper chamber 63 of the compartmentized chamber 54 via the openings 72 and piston cavity 67. Atmospheric pressure in the reference chamher establishes a pressure differential in the chamber 54 with a resulting degree of movement in the air valve 56 depending on the differential and the degree of compression of the piston spring 71. The air valve movements will be automatic over the entire range of throttle operation and will provide a substantially constant air velocity between the base of the air valve 56 and the bridge 23. This constant air velocity passing over the orifice 39 creates a substantially constant vacuum on the orifice or jet. Since the tapered metering needle 74 is operatively connected to the piston 56, movements of the piston away from and toward the bridge will necessarily increase or decrease the effective area of the orifice 39 exposed to the constant vacuum.

At the time of starting, the piston will be biased by the spring 71 into engagement with the bridge 23 with the detents 77 allowing only a minimal separation to exist therebetween. Initially the mixture passage pressure posterior of the piston is insufiicient to cause the piston to be actuated to provide a greater fuel metering effect and to, in turn, provide an enriched fuel-air mixture needed to initiate engine operation. Actually, piston movement necessary to obtain a decreased metering effect would be undesirable since it would also increase the amount of air and the fuel-air mixture would not be enriched as desired. By the use of interconnected throttle valve linkages 28 and choke shaft linkages 82, the contour '79 of the shaft 78 can be positioned in an enriching position after a predetermined degree of throttle opening. The choke shaft will be rotated and sequentially the shaft contour 79 will close off or reduce the air flow over the bridge and displace the piston relative to the bridge thereby withdrawing the tapered needle and enlarging the eifective area of the orifice 39. Choke shaft rotation will effectively reduce or vary the air flow and increase the fuel metered into the mixture passage to provide the enriched starting mixture. The contoured choke can be actuated by means of a thermostatically actuated spring 183 and a vacuum motor 184 as illustrated in FIGURE 5. The spring 183 is sensitive to engine temperatures and when the engine is cold the spring will actuate the choke shaft 178 to an enriched position comparable to that in FIGURE 7 whereby the air flow between the bridge and piston is restricted and the piston is displaced a predetermined amount to increase the effective fuel metering area. Hot air from the engine is communicated to the thermostatic element housing 182. As an engine becomes heated, the spring releases its biasing force allowing the choke shaft to be biased by the choke return spring 83 to a normal non-enriching position. Additionally, after the engine has become operative, engine pressure is transferred to the vacuum motor 184. The vacuum motor 184 exerts of force on the shaft 178 tending to overcome the bias of the thermostatic spring and to motivate the choke shaft toward its normal nonenriching position.

In the embodiment illustrated in FIGURE 8 the choke shaft 278 is biased by the spring 289 to its enriching position. Manifold vacuum communicated to the cylindrical housing 281 via the passage 284. Manifold vacuum below a predetermined value will exert a force on a vacuum motor piston 282 of sufiicient magnitude to actuate the choke shaft to its normal non-enriching position. When the engine is operated at full load or wide-open throttle, the manifold vacuum will be insufiicient to overcome the bias of spring 289 and the choke shaft will be rotated by a spring to its enriching position. In the enriching position the air flow between the air valve 56 and the bridge 23 will be restricted without a change in metering relationship between the tapered needle 74 and the fuel orifice 39. The resulting fuel-air mixture will be enriched above that normally obtainable at wide-open throttle. It will be apparent to those skilled in the art that rotation of the choke shaft 278 for enri hment would not be as great as that schematically illustrated in FIGURE 7 since full rotation would provide an enriched mixture which is too rich for the normal running power mixture. Since the embodiment illustrated in FIGURE 8 is intended to provide enrichment only at full load or wide-open throttle operation and not primarily for starting enrichment, then the degree of choke shaft rotation can be limited by the engagement of the lever 288 with the stop or limiting pin 292. If the embodiment of FIGURE 8 were intended to provide starting enrichment then a choke actuating lever could be utilized which would act as the modulating means within a predetermined intermediate degree of rotation and suitable overrun means could provide full choke operation.

It is to be understood that the invention is not limited in its application to details of construction and arrangement of parts illustrated in the accompanying drawings since the invention is capable of other embodiments and of being practiced or carried out in various ways. It is also to be understood that the phraseology or terminology employed is for the purpose of description and not of limitation, and it is not intended to limit the invention herein claimed beyond the requirements of the prior art.

I claim:

1. A carburetor for an internal combustion engine comprising:

a body provided with a mixture passage, said passage providing an air intake and a mixture outlet;

a fuel orifice opening into the passage;

means communicating with the orifice for supplying fuel to the orifice;

air valve means for restricting the air flow in the passage;

metering means operably connected to the air valve and cooperating with the orifice for restricting and regulating the fuel discharge into the air flow from the orifice;

throttle valve means in the passage for controlling the introduction of a fuel-air mixture to the engine; and,

means including a shaft supported in the passage for reducing the air flow;

means responsive to engine temperatures connected to said shaft for moving said shaft in response to temperature variation.

2. A carburetor as set forth in claim 1 wherein:

the air valve comprises a piston supported by the body and operatively extending into the passage, means mounting said piston for reciprocal movement toward and away from the fuel orifice; and,

the means for reducing air flow in the passage comprises a shaft member adapted upon rotation to reduce the air flow through the passage, said shaft being journalled in the body and having a contoured portion offset from the axis of said shaft.

3 A carburetor for an internal combustion engine comprising:

a contoured restriction formed within the passage providing a bridge;

a fuel orifice in the bridge;

means communicating with the orifice for supplying fuel thereto;

a piston air valve, means mounting said piston for movement toward and away from the bridge for restricting the air flow in the passage;

metering means operably connected to the piston and cooperating with the orifice for restricting and regulating the fuel discharge from the orifice;

a throttle valve in the passage for controlling the introduction of a fuel-air mixture to the engine;

a contoured shaft journalled in the body traversing the passage adjacent the bridge adapted for movement during predetermined engine operating conditions to reduce the air flow for enriching the mixture during said predetermined engine operating conditions; and, means for actuating the contoured shaft.

4. A carburetor as set forth in claim 3 wherein the means for actuating said contoured shaft comprises linkage means interconnected between said shaft and said throttle valve for obtaining shaft rotation at predetermined throttle valve positions.

5. A carburetor as set forth in claim 3 wherein:

the contoured shaft extremities are journalled in the body and the intermediate portion thereof is segmentally shaped and offset from the axis of said shaft to provide the contour; and,

means are provided for defining a minimum air passage between the bridge and the piston when the piston approaches the bridge.

6. A carburetor as set forth in claim 5 wherein the contoured restriction comprises a flat median portion and inclined approaches leading to and from said flat median portion, said median portion providing said bridge, one of said approaches being formed with a void crosswise of said passage; said contoured shaft being positioned in said void.

7. An air valve carburetor for internal combustion engines comprising:

a body provided with a mixture passage, said body being adapted for connection between an air intake and engine manifolding;

a contoured restriction formed in the passage further comprising:

a flat median portion providing a bridge;

inclined anterior and posterior approaches leading to and away from the bridge, one of said approaches being formed with a void transverse of the passage;

a fuel orifice in the bridge;

means communicating within the orifice for supplying fuel thereto;

a piston supported by the body and operably extending into the passage and means for mounting said piston for reciprocal movement toward and away from the bridge;

means responsive to pressure diiferentials for actuating the piston;

metering needle means carried by the piston adapted to project into the orifice for varying the fuel discharge therefrom;

throttle valve means supported in the passage posterior 0f the contoured restriction for controlling the introduction of a fuel-air mixture to the engine manifolding;

means for enriching the fuel-air mixture during predetermined engine operating conditions, said enriching means further comprising a shaft rotatably supported in the body and including a contoured portion, said shaft being positioned in the void of the contoured restriction; and

means for actuating the enriching means.

8. An air valve carburetor as set forth in claim 7 further comprising:

detent means on the piston adapted to engage the bridge for defining a minimum air passage between the piston and the bridge when the enriching means is inoperative.

9. A carburetor for an internal combustion engine comprising:

21 fuel orifice opening into the passage;

means communicating with the orifice for supplying fuel to the orifice;

air valve means for restricting the air flow in the passage;

means including a shaft in the passage for reducing the air flow; and

means responsive to engine pressure, connected to said shaft for moving said shaft in response to pressure variation.

References Cited by the Examiner UNITED STATES PATENTS 1,822,712 9/31 Skimmer 26l44 2,062,496 12/36 Brokel 261-52 2,195,867 4/40 Mallory 26l52 2,523,798 9/50 Winkler 26l50 FOREIGN PATENTS 595,815 7/25 France. 300,725 11/28 Great Britain.

HARRY B. THORNTON, Primary Examiner.

HERBERT L. MARTIN, Examiner.

Claims

1. A CARBURETOR FOR AN INTERNAL COMBUSTION ENGINE COMPRISING: A BODY PROVIDED WITH A MIXTURE PASSAGE, SAID PASSAGE PROVIDING AN AIR INTAKE AND A MIXTURE OUTLET; A FUEL ORIFICE OPENING INTO THE PASSAGE; MEANS COMMUNICATING WITH THE ORIFICE FOR SUPPLYING FUEL TO THE ORIFICE; AIR VALVE MEANS FOR RESTRICTING THE AIR FLOW IN THE PASSAGE; METERING MEANS OPERABLY CONNECTED TO THE AIR VALVE AND COOPERATING WITH THE ORIFICE FOR RESTRICTING AND REGULATING THE FUEL DISCHARGE INTO THE AIR FLOW FROM THE ORIFICE;