US2777678A

US2777678A - Carburetor

Info

Publication number: US2777678A
Application number: US370724A
Authority: US
Inventors: Stanley M Udale
Original assignee: Holley Carburetor Co
Current assignee: Holley Performance Products Inc
Priority date: 1953-07-28
Filing date: 1953-07-28
Publication date: 1957-01-15
Anticipated expiration: 1974-01-15

Description

Jan. 15, 1957 s. M. UDALE 2,777,678

CARBURETOR Filed July 28, 1955 INVENTOR.

1 2,777,678 CARBURETOR Stanley M. Udale, Detroit, Mich, assignor to Holley Carburetor Company, Detroit, Mich., a corporation of Michigan Application July 28, 1953, Serial No. 370,724 3 Claims. (Cl. 26141) The object of this invention is to improve the range of octane fuels with which a carburetor will work. This is accomplished by having the venturi automatically open up at high speeds so as to provide the simplest possible carburetor which will permit the highest possible compression ratio with a given fuel without knocking. The venturi into which the fuel nozzle discharges should open up automatically as the load is reduced and the engine speed increases. At the same time the area of the fuel orifice must be increased as the fuel ratio must remain at all times within narrow limits. At wide open throttle the fuel mixture is taken care of by a well known fuel economizer responsive to inlet manifold suction. At maximum compression and at maximum air flow the mixture must be slightly richer than 14 to 1 to permit maximum compression free from knocking.

An offset choke in the throat of the venturi upstream of the fuel nozzle and spring loaded and connected to a fuel needle valve is the solution of this problem. Air flow thus opens the choke and fuel valve simultaneously.

In the figure:

A is the air entrance.

B is the venturi in A.

C is the choke valve eccentrically mounted on a shaft Y and having its downstream lip slightly curved so that the choke valve blows open eventually.

D is the fuel nozzle discharging into B downstream of C.

E is the normal fuel orifice leading out of the float chamber L and so supplying fuel to the passage T and to the low speed fuel tube Q and to the two low speed fuel outlets R and S controlled by the throttle P in a well-known manner.

F is a cam mounted on the choke shaft Y which engages a roller H on the end of the lever I so shaped as to permit the valve C to blow wide open.

K is a compression spring engaging a needle valve G Which is lifted by the lever I when the choke valve C is opened. Needle valve G opens up a passage for fuel so as to add more fuel to that supplied by orifice E.

Valve M is the fuel for wide open throttle admitted when the pressure at opening in the mixture outlet rises and spring U acting against diaphragm N then opens valve M in a well known manner.

A choke control rod V, when moved to the right, closes choke valve C positively by collapsing the spring W. It will be noted that although the fuel needle G closes whenever the choke valve C is closed, the normal fuel orifice E always remains wide open to provide the stare ing fuel.

When choke control rod V is moved to the left the spring W permits the cam F to raise the needle valve G as the valve C opens. As the speed of the engine increases the choke C is blown more and more open and the needle valve admits more and more fuel and eventually valve C is blown wide open and the cam F raises the roller H and lifts the needle valve G to admit the maximum amount of fuel. At the same time, as the throttle P is eventually opened wide, the pressure at opening 0 rises and the valve M also rises.

It will be noted that as the choke valve is blown open the choke lever Z is moved to the left to compress the spring W; hence, the position of the rod V can be used to reduce knocking.

nite rates Patent 0 2,777,678 Patented Jan. 15,1957

Unlike all air valve carburetors, this air valve carburetor does not depend on the characteristic of the compression of the springs W and K to determine the fuel air ratio. So long as the air flow through the venturi B around the choke valve C does not approach a high value (speed of sound, for example) the depression causing fuel flow from nozzle D through orifice E and past the needle valve G will correspond to the airflow. Hence, if the engine knocks and the knocking is reduced by advancing the rod V to the right but not far enough to the right to actually choke the engine, the torque developed by the engine will be reduced at low engine speeds with throttle P wide open; but the mixture will not become excessively rich; on the other hand, if high octane fuel is used and the rod V is moved over to the left so that the choke C opens up at a lower engine speed, the mixture will not become excessively lean as is the case when the spring load on an ordinary air valve carburetor in common use thirty to forty years ago.

This is a continuation in part of my case filed July 15, 1953, Serial No. 368,142, now Pat. No. 2,741,466, issued April 10, 1956, in the name of Stanley M. Udale and an assignment to the Holley Carburetor Company.

What I claim is:

1. In a carburetor of the variable venturi type having a constant level fuel supply chamber, an air entrance of venturi form, a shaft unsymmetrically located transversely through the throat thereof, an unbalanced butterfly valve mounted on said shaft and having its downstream wing longer than its upstream wing, a fuel nozzle connected to said fuel chamber and having its discharge outlet in said throat below said upstream wing, a mixture outlet having a manually controlled throttle valve therein, a second fuel nozzle also connected to said fuel chamber and having a double fuel outlet divided by said throttle valve when in its idling position so that the discharge from the said second nozzle increases as the throttle is moved away from its idling position, a fixed fuel orifice supplying fuel to the first mentioned nozzle, a variable fuel orifice and a needle valve therefor, said variable orifice supplementing the supply of fuel from said fixed orifice to said first mentioned nozzle, mechanical linkage interposed between said needle valve and said unbalanced butterfly valve so arranged that as the unbalanced butterfly valve is sucked open after the throttle has been opened the needle valve is moved to admit more fuel to the first mentioned nozzle, yieldable means adapted to oppose opening of both the unbalanced butterfly valve and of the fuel controlling needle valve.

2. A device as set forth in claim 1 in which there are manually operated over-riding means to close the throat of said venturi for starting.

3. A device as set forth in claim 1 in which the said mechanical linkage comprises a cam mounted on said shaft outside said venturi throat, a roller that rides on said cam, a lever to which said roller is connected so that it can rotate a fulcrum for said lever, a mechanical connection from said lever to said needle valve transmitting the yieldable means to force the roller to engage said cam.

References Cited in the file of this patent UNITED STATES PATENTS 1,872,559 Bicknell Aug. 16, 1932 1,900,191 Mock Mar. 7, 1933 2,004,242 Heitger June 11, 1935 2,167,892 Kent et al Aug. 1, 1939 2,407,534 Carlson Sept. 10, 1946 2,479,392 Miller Aug. 16, 1949 2,499,554 Wirth Mar. 7, 1950 2,631,832 Hieger Mar. 17, 1953 2,646,264 Morris July 21, 1953