US2375160A - Carburetor metering device - Google Patents

Description

H.- A. WOODS n 7 2,375,160

CARBURETOR METERING, DEVICE May 1, 1945.

Filed Oct. 16, 1942 I'NVENTOR HERBERT A.WOO DS $MAQJ U N ATTORNEY Patented May 1, 1945 2,375,160 cannuna'ron METERING DEVIQE Herbert A. Woods, St. Louis, Mo.,

Carter Carburetor Corporation, St.

asslgnor to Louis, Mo,

a corporation of Delaware Application October 16, 1942, Serial No. 462,235 3 Claims. 261-44) This invention relates to carburetors for internal combustion engines and consists particuthe fuel bowl. IAS the carburetor is heated, thisrestriction may be obstructed by fuel bubbles and, furthermore, the more or less segregated body of fuel in the main nozzle passage is susceptible to boiling, particularly after the engine has stopped. which causes liquid fuel to be spilled into the carburetor and intake manifold. This condition, known in the industry as percolation" results in hard starting until such excess fuel evaporates or is carried from the manifold.

It is an object of the present invention, accordingly, to provide a carburetor in which the main fuel passages have substantially unrestricted communication with the fuel bowl and the metering of fuel is efiected at the discharge end of the nozzle. Another object is to provide for metering fuel at the discharge end of the main fuel nozzle without, at the same time, appreciably varying the main supp y of air through the carburetor.

These objects and other more detailed objects hereafter appearing are attained substantially by the device illustrated in the accompanying drawn in which Fig. 1 is a sectional view of a carburetor embodying the novel fuel metering arrangement.

Fig. 2 is an outside elevation of the carburetor showing the means for baflle.

Figs. 3 and 4 are enlarged, detail views showing the nozzle and fuel metering baflle in different positions.

Fig. 5 is a detail section taken on line 5-5 of Fig.4.

The carburetor illustrated has a downdraft inoperating the metering trolling the normal level of fuel in, the bowl. A main fuel nozzle it extends from the bowl to a point directly above the center of small venturi 6 and has a tip portion with a fuel outlet opening H facing generally across the direction of air flow, and an air inlet opening l2 facing against the air flow. The nozzle I0 is substantially unrestricted below the fuel level :r-w.

Extending across the mixture conduit above the Venturi tubes is a shaft IE of generally ci:cular cross section but having a central portion immediately adjacent the tip of nozzle it which is cut out, as at 16, so as to prevent an eccentric face I! to the nozzle tip. On one end of shaft l5 outside the body of the carburetor there is secured a small arm I8 urged counterclockwise by a spring 23 and pinned to a cam follower link is which slides longitudinally in a guide 20. A follower roller 2! on the end of this link rides on a cam 22 pivoted on the carburetor body.

The mechanism is arranged so that, as the throttle valve is moved, shaft i5 is rotated to vary the relationship of baiiie surface I! and the nozzle tip and thereby vary the effective suction on the nozzle tip and, consequently, the rate of fuel discharge therefrom. The contour of cam 22 may be varied to provide for proper proportioning of the mixture at all throttle positions. Generally, this cam will be irregular in shape.

When the throttle is fully opened, the position of shaft l5 will be as in Fig. 3, with baiiie face l1 substantially overlying and. shielding the tip of the nozzle so that increased suction is applied to the nozzle outlet. This position, furthermore,

restricts the entry of air into inlet hole I2. The position of maximum leanness is shown in Fig. 1 in which the baflie face extend beneath the nozzle tip so as to increase the pressure on the nozzle outlet. The position of the bailie in Fig. 4 is intermediate. Cam 22 is shaped to provide for the proper mixture enrichment as specified by the engine manufacturer and to obtain the maximum economy or power as determined by dynamometer tests. For instance, as the throttle is opened from the position in Fig. 1, shaft [5 may remain stationary during the part throttle positions to provide best economy, and as the throttle approaches full open position, shaft l5 may rotate clockwise to provide a richer or power mixture.

The major portion of shaft l5 being of circular section, rotation of this shaft does not materially affect the .total quantity of air flowing through the carburetor. The small cut-out portion I6 into which the nozzle tip extends replaces the small primary venturi into which the nozzle extends in some carburetors. The carburetor may be provided with suitable auxiliary fuel systems such as the idling, accelerator, and step-up economizer devices generally used.

The free communication between fuel bowl and the main nozzle insures that the temperature of fuel in the nozzle will be substantially the same as that of the larger body of fuel in the bowl and, consequently, the temperature of the home fuel does not rise so rapidly after the engine has stopped and percolation is substantially reduced or eliminated. In any particular carburetor, baiiie face l1 need not be adjustable to the extreme positions shown in the figures, these being merely illustrative of the possibilities of the device. Of course, the size of holes II and II in the nozzle tip may be varied to provide for the proper mixture proportions. The fuel metering arrangement is, accordingly, quite flexible and permits accurate calibration of the carburetor.

The arrangement may be modified in various respects as will occur to those skilled in the art and the exclusive use of all modifications as come within the scope of the appended claims is contemplated.

I claim:

1. In a carburetor air induction conduit, a constant level chamber, a fuel nozzle projecting into said conduit and having a tip portion above the fuel level, said portion having a discharge opening facing across the direction of air fiow and an air inlet opening facing against the air how, and a relatively small, generally cylindrical shaft extending across said conduit and having a deformed part immediately adjacent said tip por- 35 tion and presenting an eccentric face thereto, said baiile being rotatable to variably affect the air fiow past said nozzle openings and, consequently, the metering of fuel through said nozzle. 2. In a carburetor, an induction conduit, 9. throttle, a fuel nozzle having an orifice opening into said conduit, a generally cylindrical shaft extending transversely into said conduit with its axis close to said orifice and having a cut-out part providing a face substantially on a chord of the shaft immediatclyconfronting said orifice, and means to rotate said shaft to alter the position of said face relative to said opening and thereby affect the functioning thereof, the diameter of said shaft being substantially less than that of said conduit and said face extending only the width of said nozzle so that only the air fiow substantially in line with said opening is affected by movements of said shaft. 3. In a carburetor, an induction conduit, :1. throttle, a. venturi, a fuel nozzle having an orifice arranged to discharge fuel into said conduit, a shaft extending across said conduit, said shaft having a portion cut-out to form an eccentric face immediately adjacent said fuel outlet opening, and means operable by movement of said throttle to rotate said shaft to variably divert the air flow away from said nozzle and thereby affect the nozzle fuel discharge, the eccentric face of said shaft extending only substantially the width of said nozzle so that rotation of said shaft does not substantially affect the total air flow through said conduit.

HERBERT A. WOODS.

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