Sit",17762A May

Aug. 8, 1967 M. F. STERNER 3,334,878 UPDRAFT CARBURETOR BODY AND METHOD FOR MAKING THE SAME Filed April 7, 1965 2 Sheets-Sheet M/1/2M/7 oa M%Zu/M/ a. s. 7aawaa ...sit",17762a May/ 3,334,878 United States Patent Office Patented Aug. 8, 1967 2 Surfaces which have to be machined or enlarged to main 3,334,878 UPDRAFT CARBURETOR BODY AND METHOD tain efficiency or flow capacity; also, it does not permit FOR MAKING THE SAME coring the many small passages required in a carburetor Melvin F. Sterner, Bloomfield Hills, Mich., assignor to so that costly machining is required. In any event, cast Holley Carberetor Company, Warren, Mich., a corpo iron cannot be die cast because its high melting point ration of Michigan would soon damage the dies. Filed Apr. 7, 1965, Ser. No. 446,344 As opposed to sand casting, die casting provides smooth 4 Claims. (CI. 261-72) surfaces which often need not be machined. It also pro vides closer tolerances, enables thin sections, which are This invention relates to internal combustion engine 10 desirable in aluminum castings to avoid porosity, and carburetors, and more particularly to a single piece body, gives a weight to strength ratio comparable to cast iron. and method of making the same, for updraft type carbu While the permanent dies required for die casting process retors for engines driving agricultural type tractors. are very costly and cannot be justified except for relative To applicant's knowledge, it has been and is the uni ly high volume production, tractor carburetor volumes versal practice to employ updraft type carburetors hav 5 appear to be increasing so that the tooling appears justi ing a generally L-shaped induction passage for agricultural fied; also, die casting materials, such as aluminum, for and industrial type tractor engines, and there are good carburetor bodies has now been accepted in the passenger reasons for this. One reason for avoiding a downdraft vehicle field. type carburetor is that it is mounted at the top of the A recent development in the agricultural tractor field is engine, which would necessarily raise the hood level and 20 a three cylinder engine having relatively severe pulsations interfere with the operator's visibility. A reason for avoid in the intake manifold. By close observation, it was dis ing horizontal carburetors is that side clearance must covered that running this engine at wide open throttle be maintained; that is, tractors are often provided with with certain prior art tractor carburetors and without an power equipment which may include movable hydraulic air cleaner causes a considerable amount of fuel to be cylinders mounted to the tractor frame close to the side 25 ejected from the carburetor air inlet. of the engine. Also, tractors of this type often operate This problem does not occur when running the same under adverse conditions, such as in wooded terrain where engine under the same conditions with a carburetor hav tree branches and other similar obstacles may damage ing a body formed in a manner proposed herein. It is a horizontal draft carburetor or other part extending later believed that this is attributable to the fact that a carbu ally from the engine. 30 retor body made according to the invention provides a Another problem is that almost all tractors of this reservoir in the air inlet directly below the venturi that kind have fuel tanks mounted above or high at one end apparently absorbs or dampens the engine pulsations. of the engine, providing a gravity feed and eliminating That is, the opening at the bottom of the carburetor body the need of a fuel pump. If a downdraft carburetor were required to withdraw the core is closed by a flat plate employed and the fuel inlet valve stuck open, the entire against which the pulsations impinge and "bounce' back contents of the fuel tank would drain directly into the toward the venturi, tending to oppose the next pulsation engine, causing dilution of the crank case oil and hy and improving engine operation. draulic locking of the engine cylinders. With an updraft At least some portion of the fuel ejected from the air carburetor, the fuel will merely spill onto the ground. inlet of prior art carburetors due to severe pulsations Another feature of prior art tractor carburetors is that 40 would be at least temporarily lost in the air cleaner, re the bodies thereof are, almost without exception, made sulting in faulty distribution of the fuel. However, with a from cast iron sand castings. In the tractor industry, the carburetor made according to the invention, pulsations are tradition has been durability and ruggedness; cast iron reduced and the fuel is not ejected from the air inlet; supplies those properties, and there has been a natural therefore, the fuel distribution is improved. This has been reluctance to change to other modern materials such as 45 observed by running a carburetor made according to the aluminum. invention with a flat Plexiglas plug to close the core open Almost all prior art tractor carburetors are cast in two ing at the bottom of the carburetor; specifically, it has sections, a throttle body section and a fuel bowl and air been observed that engine pulsations cause fuel to be al horn section which are subsequently assembled with a ternately deposited and immediately removed from the gasket therebetween, the gasket always being a potential 50 Plexiglas plug. This immediate recapture of a lesser point of leakage. The fuel metering body is, in all cases, amount of pulsated fuel obviously results in improved formed integrally with the fuel bowl; that is, one side engine operation. In other words, any pulsated fuel has of the metering body is attached to the inner wall of the sufficient inertia so that it deposits on the flat closure fuel bowl so that it is not subjected on all sides thereof for the core opening, rather than entering the air inlet, to the cooling effect of the fuel in the bowl. The latter 55 as it does in prior art carburetors wherein the junction construction, together with the fact that tractors of this of the air inlet and the bore is formed with a radius or kind have an open engine compartment and are operated the junction contains structure having surfaces from which for long periods of time, often under direct exposure the fuel can deflect into the air inlet. to the heat of the sun, so that the engine fan provides Accordingly, an object of the invention is to provide an less efficient cooling than the fan in a passenger car hav 60 ing a closed engine compartment, causes heat problems updraft carburetor body that can be die cast so as to re resulting in metering of fuel vapors along with solid fuel duce carburetor machining and assembly costs. for which the carburetor was calibrated. This heat prob Another object of the invention is to provide, for use lem is further aggravated by the fact that cast iron has on tractor and other similar engine applications, a one a lower specific heat and lower heat conductivity, as com 65 piece updraft carburetor body that includes the mounting pared to other materials such as aluminum. flange and throttle body, the fuel bowl cover and fuel Of necessity, the capacities of prior art cast iron tractor metering section and the air horn portions thereof, and carburetors are varied by machining or a press fit venturi; that is adapted to be die cast from aluminum or other in the latter case, a different venturi is inserted into the modern material. induction passage of the same carburetor body when it 70 Still another object of the invention is to die cast a is desired to change the capacity of the carburetor. Fur single piece carburetor body by the use of three cores, in thermore, sand coring of cast iron provides rough passage which case the cores can be made in sets so that carbu 3,334,878 3 4. retors of different capacity can be provided from the same casting comprises an L-shaped structure, one leg of which die merely by substituting a different set of cores. comprises a horizontal air horn section 12 and the other Another object of the invention is to provide a one piece leg of which comprises a vertical throttle body and ven die cast carburetor body having an integral fuel bowl turi section 14, the free end of the section 14 terminating cover, the bowl sealing surface of which is located above in the usual flange 16 by which the carburetor would be the normal fuel level in the bowl, and a metering section bolted to the engine intake manifold. It will be recognized depending therefrom in a manner so that a separately that the terms horizontal and vertical are employed as a formed fuel bowl may be secured to the carburetor, the matter of convenience, since the carburetor would be result being that the metering section is suspended in and mounted at the side of the tractor engine in substantially entirely surrounded by the fuel so as to be cooled thereby O the position shown in FIGURE 1. In use of the completed and does not at any point touch the fuel bowl wall. carburetor, a hose connection would be made between an Another object of the invention is to provide such a one air cleaner and the free end of the air horn, the continu piece updraft carburetor body having an integrally formed ous bead 18 on the outer surface of the free end of the fuel inlet seat and float hinge pin trunnions, as well as air horn being provided to improve the seal of the hose universal choke and throttle shaft and lever mountings connection.

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