US3207491A - Fuel metering device for carburetors - Google Patents

Description

Sept 21 1965 w. G. KINGsLr-:Y ETAL 3,207,491

FUEL METERING DEVICE FOR CARBURETORS original Filed July 7, 1961 3 Sheets-Sheet l INVENTORS ggamf ATTQRNEY WITNESS.' [M dan;

Sept 21 1965 w. G. KINGsLEY ETAL l 3,27,491

FUEL METERING DEVICE FOR CARBURETORS Original Filed July 7, 1961 3 Sheets-Sheet 2 22522. wim; W f

ATTORNEY A Sept 21, 1955 w. G. KINGsLEY ETAL, l 3,207,491

FUEL METERING DEVICE FOR CARBURETORS Original Filed July 7, 1961 5 Sheets-Sheet 3 il *C T j i3 4 Il l l l [//L l5 INVENTOR. WARREN G. KINGSLEY ALBERT H. WINKLER A TTORNE Y United States Patent O 3,207,491 FUEL METERING DEVICE FR CARBUREERS Warren G. Kingsley, Watkins Glen, and Albert H.

Winkler, Elmira, N.Y., assignors to The Bendix Corporation, Elmira Heights, N.Y., a corporation of Delaware Original application July 7, 1961, Ser. No. 122,462. Divided and this application .lune 18, 1962, Ser. No. 203,162

3 Claims. (Cl. 261-44) This application is a division of the copending Kingsley application, Serial No. 122,462, filed July 7, 1961.

The present invention relates to an improvement in a carburetor for internal combustion engines and, in general, relates to an improvement in the air valve type of carburetor. More particularly, the invention relates to fuel metering means for air valve carburetors which are adapted for controlling fuel vapor and percolation occurring between the fuel chamber and the fuel discharge orifice.

An air valve carburetor may include either a piston, poppet, butterfly, etc., type of valve that is responsive to air liow changes. In the ca-se of a piston type air valve the piston is mounted in the body and a compartmentized chamber articulates the piston for reciprocal movement in the mixture passage to provide an approximately constant air velocity over the metering orifice of a fuel jet assembly. A tapered needle valve carried by the piston projects into the orifice disposed in a bridge portion of a contoured restriction in the mixture passage to provide the fuel metering means. The piston and needle valve in combination are frequently referred to as the air valve. Posterior of the contoured restriction a throttle valve controls the introduction of the fuel-air mixture to the engine manifolding. Reciprocal piston movement to vary the air flow responsive to throttlevalve position changes 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 a substantially constant air velocity and a substantially constant vacuum between the air valve, the bridge and the fuel orifice. Differences in the vacuum existing in the mixture passage between the bridge and throttle valve are communicated to the compartmentized chamber and will cause piston movements so as to vary the air flow and maintain the value of vacuum asserted on the orifice at a substantially constant Value. Since the needle valve is connected to the piston, any movement of the piston will necessarily vary the needle valve-jet assembly orifice restricting characteristics by varying the effective orifice area and allowing a greater or lesser amount of fuel to be atomized.

Air valve carburetor constructions, as heretofore used or proposed, have one very definite limitation, that being poor vapor control characteristics. The prior art structures use a separately located fuel chamber and an associated fuel metering means both -of which are exposed to ambient heat, a construction which tends to be highly susceptible to the creation of fuel vapor and percolation. The fuel vapor difficulties are generally known to occur between the fuel chamber and the metering orifice opening into the induction or mixture passage. It is, therefore, a primary object of the present invention to provide an air valve type of carburetor with a fuel chamber and fuel jet assembly having desirable fuel Vapor and percolation control characteristics.

It is an object of the present invention to provide a fuel metering means for carburetors which is simple in construction, efficient and reliable in operation, and economical to manufacture and fabricate.

3,207,491 Patented Sept. 21, 1965 ice It is an object of the present invention to provide a fuel jet assembly, including vapor and percolation controlling means therein, for an air valve carburetor.

It is another object of the present invention to provide an air valve carburetor using an attached fuel chamber supported by the carburetor body adjacent a contoured restriction in the mixture passage, and having a fuel jet assembly communicating between the mixture passage and the fuel chamber, said jet assembly including vent means within its structure adapted to circulate fuel vapor back into the fuel chamber and away from the fuel metering orifice of the fuel jet assembly.

It is still another object of the present invention to provide an air valve carburetor having a fuel jet assembly which is surrounded by a cooling fuel supply to thereby assist in the prevention of fuel vapors and percolation.

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 which it pertains from the following description of the preferred embodiment thereof described with reference to the accompanying drawings in which similar reference characters represent corresponding parts throughout the several views, and, in which:

FIGURE l is a longitudinal sectional View illustrating an air valve carburetor embodying the present invention;

FGURE 2 is a bottom view, partly broken away and in section, illustrating an air valve carburetor embodying the present invention; and,

FIGURE 3 is a longitudinal view partly in section taken along the section line 33 of FIGURE 2, illustrating in particular a float operated valve mechanism for maintaining normal fuel level. FIGURE 3 shows a conventional float-operated valve mechanism. No part of said fuel valve detail constitutes part of the invention.

Now referring to the drawing and more particularly to FIGURE l, 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 iiat rectangular median portion 23 commonly referred to as a bridge. The bridge portion 23 is 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 lsupported on the throttle shaft 26 journalled in the body to control the introduction of the fuel-air mixture to the engine manifolding (not shown). A throttle return spring 27 (FIGURE 2), 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 2) and is controlled in a normal manner by a float actuated valve 15 (FIGURE 3) which provides a normal fuel level within the fuel chamber. A vent in the body 25 communicates atmospheric pressure from the passage 73 to the interior of the fuel chamber. A hollow member 30 formed as a depending portion of the body extends downwardly into the fuel chamber. The upper extremity of the memberI Sti opens into the induction or mixture passage through the aperture 34 which is centrally disposed in the bridge. The lower extremity of member 30 is threaded as at 35. Supported by the threaded extremity in the cylindrical cavity 31 of the hollow member 30 is the fuel jet assembly generally indicated as 32. The jet assembly extends into the fuel chamber 14 with the major portions of the assembly being surrounded by fuel and, of course, being below the normal fuel level.

The jet assembly 32 consists of a hollow'bushing 33 extending upwardly through the aperture 34 of the hollow member 30. The hollow bushing retaining screw 36 is threadedly received in the threaded extremity of the member 30 and has portions thereof extending upwardly into the cylindrical cavity 31 tok maintain the bushing 33 in contact with the underside of the body adjacent the bridge. The hollow bushing retaining screw extends downwardly 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. The hollow bushing 33 and the hollow bushing retaining screw may be broadly defined as hollow means. A tubular orifice member 39 slidably positioned in the 'bushing 33 extends therethrough to the surface of the bridge 23 to provide the mixture passage metering orifice. The tubular orifice member is maintained in proper positional relationship relative to the bridge surface 23 by an orifice adjusting screw 41 threadedly received in the hollow bushing retaining screw 36 and a spring 42 is compressively confined between a flange43 on the tubular orifice member 39 and a recess 44 formed in the hollow bushing 33 to properly bias the orifice member. A plug 52 closes the exterior opening of the bushing retaining screw. The tubular member 39 and its adjusting means 41 may be broadly defined as tubular means.

Fuel from the chamber 14 will flow through the fuel passages or openings 46 which are formed in the hollow bushing retainer 36 below the normal fuel level, thence through the channel means 47 located in the orifice adjusting screw locating below the passages 46 and lthence through the tubular orifice member 39 to the mixture passage discharge orifice in the bridge. The exterior of the fuel chamber is exposed to great amounts of heat generated by the engine and generally trapped under the hood or bonnet surrounding or covering t-he engine. Even greater amounts of heat are transferred to the carburetor through the carburetor mounting flange connecting the device to the engine. Consequently, the fuel chamber serves as a heat sink to transfer much heat to the fuel within the chamber itself.`

-F-uel vapor and percolation difficulties generally arise when the engine ceases to operate and the fuel movement through the chamber is stopped or when the engine is operated at low speeds Iand light loads immediately after a hard hot run. Under such circumstances the fuel when becomes very warm due to the absorbed heat with the consequential result that the light ends of the fuel vaporize. When the engine is inoperative and this vaporizati-on occurs then localized instantaneous pressure differentials are generated within the metering system notwithstanding the pressure equalizing vent between the fuel chamber and passage 73. This instantaneous pressure will cause fuel to -be discharged from the metering orifice into the mixture passage 16 if the fuel metering system does not incorporate the subject inventive features which provide proper ventilation and insulation for the fuel. Fuel discharged into the induction passage by su-ch instantaneous pressure will cause hard starting due to an overly rich mixture.

In the case -where the engine is operated at low speeds and light loads immediately after a hard hot run andthe subject inventive features are not incorporated in the fuel metering system, the fuel as it iiows through the metering system will absorb sufcient heat to vaporize the light ends of the fuel thereby creating vapor bubbles in the jet assembly 32. IIf the vapor ybubbles are not separated from the liquid fuel, then the vapor bubbles will affect the fuel output at the metering orifice in the mixture passage and a leaner mixture which is deteri-mental to smooth engine operation will result.

The aforesaid vapor problems can be eliminated through the use of the hereinafter described invention. The trapped air or fuel vapor created as above described within the jet assembly 32 will rise to the spatial separation 45 defined by the interior walls of the hollow means and the exterior walls of the tubular means. The vapors then pass through vent orifices 48 locating in the hollow bushing retainer 36 above the fuel passage means 46. The vent -orifices 48 open into another spatialseparation 49 ydefined by the upper portion of the cylindrical cavity 31 and the exterior wall portions of the hollow means. A vent means 51 communicates the vapors between the spatial separation 49 and the area 50` of the fuel chamber. T-he vent means 51 is adjacent the -body and locates well above the normal fuel level. In this manner vapor occurring withinthe fuel jet assembly is effectively eliminated. Vaporized fuel is thus circulated within the fuel chamber and the upper portions of the jet assembly, however, the vapor is directed away from the central portion of the fuel chamber containing the tubular means. Since the fuel channel means `47 are lower than the fuel passage means 46 generally most of the vapor entrained fuel and the liquid fuel will be separated in the spatial separation or chamber 45. The vapor will rise within the chamber while the liquid fuel will liow through channel means 47 into the tubular means. Due to the jet assemblys structure the tubular means which provides the mixture passage metering structure is located in a position remote from the heated portions of the carburetor and, therefore, it is least susceptible to the fuel vaporization problem. Initially a small but not detrimental amount of vapor may form in the tubular means when the light ends of the fuel therein are vapor-ized but the heavier fuel (the fuel that has already given up .its light ends in the spatial separation 45) when they enter the tubular means have fewer tendencies to vaporize. The fuel in the spatialseparation 45 also reduces the temperature of the fuels within the tubular means and hence further reduces any vaporizing tendencies of the fuel therein. While the fuel supply within the tubular means will be somewhat reduced, a sufficient amount will nevertheless remain in a liquid state to assure a suicient fuel supply for starting. Simultaneously, the vaporizedfuel is circulated through the chambers -45 and 49 and vents 48 and 51 back into the fuel chamber without detrimentally affecting the fuel supply in the tubular means of the jet assembly.

The remainder of the carburetor construction is not particularly pertinent to the subject invention but will be hereinfater briey described. Formed as a part of the body 12 .and lopening upwardly from the mixture passage 16 is a substantially inverted conical structure which combines with the cover assembly 13 to provide the compartmentized chamber generally designated as 54. Slidably supported within the chamber 54 and the mixture passage 16 is a piston 56. 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 at its inner periphery is clamped between the piston 56 and a diaphragm retaining washer 59. The outer periphery of the diaphragm is clamped between the mating fianges 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 chamber 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 the 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. The pressure drop created by the air fiow between the bridge and the base of the piston is communicated to the suction chamber 63 by an opening 72 formed in the base of the piston. Thus the induction pressures existing in mixture passage 16 between the throttle valve 24 and the bridge 19 are communicated via the opening 72 and the piston cavity 67 to the suction chamber 63. A reference pressure, usually atmospheric, is communicated to the reference chamber 64 by a passage 73. This passage in the present embodiment is vented to the air entrance through 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.

Operatively connected to the piston is a tapered metering needle valve 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 valve is secured to the piston by any convenient means such as the set screw 76. The piston S6 and the needle valve 74 in combination are generally referred to as the air valve.

Means in the form of punctiform detents 77, best illustrated in FIGURE 2, 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 detents 77 could, of course, be accomplished by other means (not shown) positioned in the body or in the conical structure of the body which are adapted to engage the piston during its reciprocal movement so as to establish a lower limit of piston travel.

It is to be understood that the invention is not limited in its application to the 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. An air valve carburetor comprising, in combination,

a body means including air induction passage means adapted for connection to an engine;

an air valve means including a variable choke piston means and a needle valve means, supported by the body means for movement within the induction passage means, said choke piston means adapted to control the air ow through the induction passage means;

air valve adjusting means for actuating the air valve means;

a fuel chamber means supported by the body means including means providing a normal fuel level within the chamber means;

fuel jet means communicating between the induction passage means and the fuel chamber means, said needle valve means being adapted to cooperate with the fuel jet means for controlling the fuel flow drawn into the air How;

said fuel jet means including an outer hollow cylindrical means fixed at its upper end to the body means and extending below the surface of the fuel in the fuel chamber means;

an intermediate hollow cylindrical means fiXedly mounted coaxially within said outer means, so dimensioned as to leave a primary cylindrical space therebetween; an inner hollow cylindrical means mounted coaxially within said intermediate means, so dimensioned as to leave a secondary cylindrical space therebetween, and having at its upper end a jet opening admitting said needle valve means into its interior space; said intermediate hollow cylindrical means having an opening below the level of the fuel in the fuel chamber means for admitting fuel to said secondary space between the intermediate and the inner cylindrical means, said inner hollow cylindrical means having an opening below the level of the fuel in the fuel chamber means for admitting fuel from said last-mentioned space into the interior space of said inner cylindrical means,

said intermediate hollow cylindrical means having an opening connecting said secondary space between the intermediate and the inner cylindrical means with said primary space between the intermediate and the outer cylindrical means, and

said outer hollow cylindrical means having an opening above the level of the fuel within the fuel chamber means serving as a vent for the last-mentioned space into the fuel chamber means.

2. An air valve carburetor as set forth in claim 1 in which the opening into the interior of the inner hollow cylindrical means is below the level of the opening in the intermediate hollow cylindrical means for admitting fuel into said secondary space between the intermediate and the inner cylindrical means.

3. An air valve carburetor as set forth in claim 2 in which the opening in the intermediate hollow cylindrical means connecting said secondary space between the intermediate and the inner cylindrical means with said primary space between the intermediate and outer cylindrical members is adjacent the upper end of said secondary space.

References Cited by the Examiner UNITED STATES PATENTS 1,822,712 8/31 Skinner 261-44 2,062,496 12/ 36 Brokel 261-44 2,363,223 11/ 44 Bonnier 261-44 2,611,594 9/ 52 Anderson 261-72 2,988,345 6/61 Kolbe et al 261--50 FOREIGN PATENTS 300,725 1 l/ 28 Great Britain.

HARRY B. THORNTON, Primary Examiner,

HERBERT L. MARTIN, Examiner.v

Claims (1)

1. AN AIR VALVE CARBURETOR COMPRISING, IN COMBINATION, A BODY MEANS INCLUDING AIR INDUCTION PASSAGE MEANS ADAPTED FOR CONNECTION TO AN ENGINE; AN AIR VALVE MEANS INCLUDING A VARIABLE CHOKE PISTON MEANS AND A NEEDLE VALVE MEANS, SUPPORTED BY THE BODY MEANS FOR MOVEMENT WITHIN THE INDUCTION PASSAGE MEANS, SAID CHOKE PISTON MEANS ADAPTED TO CONTROL THE AIR FLOW THROUGH THE INDUCTION PASSAGE MEANS; AIR VALVE ADJUSTING MEANS FOR ACTUATING THE AIR VALVE MEANS; A FUEL CHAMBER MEANS SUPPORTED BY THE BODY MEANS INCLUDING MEANS PROVIDING A NORMAL FUEL LEVEL WITHIN THE CHAMBER MEANS; FUEL JET MEANS COMMUNICATING BETWEN THE INDUCTION PASSAGE MEANS AND THE FUEL CHAMBER MEANS, SAID NEEDLE VALVE MEANS BEING ADAPTED TO COOPERATE WITH THE FUEL JET MEANS FOR CONTROLLING THE FUEL FLOW DRAWN INTO THE AIR FLOW; SAID FUEL JET MEANS INCLUDING AN OUTER HOLLOW CYLINDRICAL MEANS FIXED AT ITS UPPER END TO THE BODY MEANS AND EXTENDING BELOW THE SURFACE OF THE FUEL IN THE FUEL CHAMBER MEANS; AN INTERMEDIATE HOLLOW CYLINDRICAL MEANS FIXEDLY MOUNTED COAXIALLY WITHIN SAID OUTER MEANS, SO DIMENSIONED AS TO LEAVE A PRIMARY CYLINDRICAL SPACE THEREBETWEEN; AN INNER HOLLOW CYLINDRICAL MEANS MOUNTED COAXIALLY WITHIN SAID INTERMEDIATE MEANS, SO DIMENSIONED AS TO LEAVE A SECONDARY CYLINDRICAL SPACE THEREBETWEEN,

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