US2182393A - Carburetor - Google Patents

Description

Dec. 5, 1939. F. 0. BALL ET AL CARBURETOR I Filed Dec. 31, 1937 Maw wmmwm l 4w 4 M m f, QM RH sm a mm 9 m w Patented Dec. 5, 1939 UNITED STATES PATENT OFFEE CARBURETOR Application December 31, 1937, Serial No. 182,765

2 Claims.

This invention relates to improvements in carburetors.

More particularly, the invention pertains to improved carburetor pick-up pump systems. One of the main objects of this invention is the provision of improved means for relieving the discharge outlet of a pick-up pump system of that effect of the normal carburetor suction which tends to pull over fuel therefrom when additional fuel is not desired.

Another object of the invention resides in the provision of an improved carburetor fuel pull over discharge preventing means of this character I which utilizes the vacuum in the carburetor fuel mixture passage for reducing the effective weight of the pick-up system check valve while this valve is seated to prevent undesirable fuel pull-over.

Further objects of the invention are to provide 0 in a fuel pull-over discharge preventing means of this kind a valve adapted when seated to prevent undesirable fuel pull-over and which is so constructed and arranged with respect to the rest of the carburetor that its effective weight is reduced by carburetor suction so that only a relatively small force is necessary to unseat the valve; to provide in a carburetor in which the pull-over valve lifting force is derived either directly or indirectly from accelerator action, improved fuel pull-over obstructing mechanism which can. be I moved to an unobstructing position without necessitating a high accelerator pedal pressure requirement; and to provide mechanism of this character by which is facilitated the prompt discharge of fuel from the pick-up system upon initial operation of the accelerator pedal.

Other objects and advantages of the invention will be more apparent from the following description taken in connection with the accompanying drawing, in which:

Fig. 1 is a central vertical sectional view of a carburetor embodying the invention.

Fig. 2 is a horizontal sectional view taken as indicated by the line 2-2 of Fig. 1.

In the form of the invention shown in the drawing, the improved pick-up pump system is shown as embodied in a carburetor, generally designated by the numeral 5, having a body portion 6 comprising die cast wall structure and a cover portion I. Formed in the wall structure of the body portion 6 is a cylinder 8 in which a piston 9 is reciprocably mounted. A piston rod 10 is attached at its lower end to the piston 9 and has an en- :larged head end portion H. A spiral spring 52 bearing between the piston 9 and the cover I, normally urges the piston downwardly, as viewed in Fig. 1, toward the discharge end of its cylinder 8.

Provided in'the body portion a of the carburetor is pump actuating mechanism comprising a vertically shiftable rod 13 which is slidably mounted in the wall structure of the carburetor. A substantially horizontal slotted plate portion M formed on the upper end of the rod 53 extends laterally therefrom into registration with the upper end portion of the piston rod H3, and slidably receives the piston rod Hi.

The carburetor 5 has a fuel mixture passage l5 provided with an upper air inlet end it and a fuel mixture discharge end H which registers with a fuel mixture passage section it formed in a throttle body portion 49. A throttle valve 2% mounted on a valve stem 2! which is journaled in apertures in the wall of the throttle body 59, serves to control the flow of fuel mixture from the carburetor. The valve stem 2! has an external end portion on which is mounted a bell crank lever 22. A link 23 operatively connects the lower end portion of the pump actuating member I3 to one arm of the bell crank lever 22. A suitable tension spring 24 of predetermined strength is preferably attached to one arm of the bell crank lever 22 and anchored on a lug 25 of the throttle body for normally urging the throttle valve toward its closed position and for urging the rod I3, piston rod l9 and piston 9 to their uppermost positions against the action of the spring l2. When the throttle valve 230 is opened, the plate i4 is moved downwardly, there-- by permitting the spring 62 to urge the piston 9 throughout its full fuel displacing stroke immediately upon opening of the throttle valve.

Fuel is admitted into the interior of the cylinder 8 during upward movement of the piston 9, through a valve controlled port 26 which is supplied with liquid fuel from the interior of a fuel reservoir 21. The normal fuel discharge is fed from the reservoir 21 through passages 23 and 29 to a main discharge nozzle 3!; located centrally of the fuel mixture passage l5. This fuel nozzle is located substantially at the maximum restriction provided in the fuel mixture passage l5 by a venturi 3i.

Fuel displaced from the cylinder 8 is fed to the fuel mixture passage It by a liquid fuel passage 32 leading from the lower end portion of the cylinder 8 through the wall of the body portion of the carburetor and communicating with the fuel -miXture passage l5 through an outlet opening 33 substantially at the location of maximum constriction of the venturi 3 I, and therefore substantially-at the region of maximum suction of the fuel mixture passage. The outlet end portion 34 of the liquid fuel discharge passage 32 may be somewhat restricted in size.

Provided at the junction of the restricted out let branch 34 and the main length of the liquid fuel passage 32 is a valve chamber 35 in which is mounted a ball check valve 35 having a comparatively close fit with the wall of the chamber and adapted to seat in and close the liquid fuel pas sage 32 as illustrated. In the upper end portion of the chamber 35 is a plug 3'! having a restricted passage 38 therethrough which communicates preferably with the fuel reservoir 2'! where there are substantially normal atmospheric pressure conditions. The check valve 36 is adapted to close the passage 38 of the plug 31 when the valve 36 is raised to seat upon the inner extremity of the passage 38 by fluid pressure applied on the; liquid fuel of the cylinder 8 by the piston 9 in order to prevent the discharge of liquid fuel therethrough. When the valve 36 is closed its diameter is preferably disposed below the location at which the passage 3d opens into the valve chamber 35.

The passages 34 and 38, or their orifices if used, are so predetermined in size that a reduc tion in air pressure below atmospheric pressure is produced in the chamber 35 and above the ball valve 36, by the vacuum of the fuel mixture passage. The resulting vacuum above the valve tends to lift it off of itsseat and thus assists in opening the valve at the initial period of discharge from the fuel system. This action of the carburetor suction reduces the effective Weight of the check Valve 36 while seated on the passage 32 and the piston operating spring i2 is not called 1 upon to lift the entire weight of the valvein order 1 to discharge the temporary fuel augmenting charge from the cylinder 8. As a result, this spring may be of weaker constructionand the throttle valve closing spring which is relied upon Q to compress the spring I2 may accordingly be of j weaker construction, thereby reducing accelerator pedal pressure requirement. Prompt openpassage may be constructed to open into the fventuri either above or below the location of 1 ing action of the valve 35 is thus facilitated without excessive pedal pressure requirement and substantially instantaneous discharge of the pick-up 1 charge is assured during initial throttle move- 50 ment.

Any liquid fuel which might escape through the air passage 38 is safely returned to the reservoir 1 2'! instead of being lost or being discharged into j the fuel mixturepassage l5.

While the passage 34 is shown to communicate with the fuel mixture passage of the carburetor lmaximum restriction as desired to predetermine the pressure characteristics.

Various modifications and changes will be apparent from the teachings of the invention as ;set forth in'the appended claims, and it is not our lintention to limit the invention to the particular idetails of construction and operation shown and described for illustrative purposes.

What we claim is:

1. In ,a carburetor including a fuel mixture passage having a throttle valve therein and including a resilient member for urging said throttle valve toward its closed position; a pick-up pump system including a fuel cylinder, a fuel displacing element in said cylinder; means including a spring adapted to be loaded by the throttle valve closing action of said resilient member for moving said element through its fuel displacing stroke during opening movement of said throttle valve; means for conducting fuel from said cylinder to said fuel mixture passage including a valve chamber having an air inlet thereto, a. passage section leading from said cylinder to said chamber, and a passage section leading from said chamber to said-fuel mixture passage; a reciprocable valve in said chamber be tween said air inlet and the outlet end of said first mentioned passage section having substantially close fitting sliding relationship with respect to the walls of said chamber and normally the close fitting portion of said valve and said chamber walls in order to apply on said valve a vacuum tending to unseat the valve.

2. In a carburetor having a fuel mixture passage having a throttle valve therein and a resilient member for urging the throttle valve toward its closing position and fuel reservoir; a pick-up pump system including a fuel cylinder; a fuel displacing element in said cylinder; means including a spring adapted to be loaded by the throttle valve closing action of said resilient member for moving said element ,through its fuel displacing stroke during opening movement of said throttle valve; means for conducting fuel from said cylinder to said fuel mixture passage including a valve chamber having an air inlet, a

passage section leading from said cylinder to said 5 chamber having an outlet communicating with the latter at a location spaced from said air inlet,

and a passage section leading from said cham ber to said fuel mixture passage; valve seats in 1 said chamber adjacent said outlet andsaid air inlet respectively, a reciprocable valve in said chamber between said valve seats having substantially close fitting sliding relationship with respect to the walls of said chamber and adapted 3 to alternatively close the outlet of the first mentioned passage section and said tively, jcommunicating with said chamber at a location I air inlet respecsaid second mentioned passage section between said air inlet and the close fitting portion of said valve and said chamber walls in order to apply on said valvea Vacuum tending to unseat the valve from said first mentioned passage section when said throttle valve is closed.

substantially FREDERICK fo'. BALL. THOMAS M. B LL.

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