Carburetor fuel metering valve

Claim 1

A fuel metering valve for a carburetor comprising: a pair of slidably interfitting relatively rotatable valve sleeves; means on said sleeves for relatively rotating said sleeves between idling and high speed positions; said sleeves having a pair of primary circumferentially overlapping fuel metering ports whose overlap area is progressively increased by relative rotation of said sleeves from said idling position to said high speed position; said sleeves having a pair of high speed fuel metering ports which are displaced circumferentially of said sleeves and hence closed throughout the major portion of the relative rotation angle of said sleeves from idling to high speed position and enter into overlapping relation only as said sleeves approach said high speed position; the inner sleeve having a fuel passage communicating with the fuel ports in said inner sleeve and opening through one end of said inner sleeve; and valve means for regulating the effective flow area of said passage including an annular valve seat about said passage between said inner sleeve fuel ports and said one end of said inner valve sleeve, a needle valve extending centrally through said passage in radially spaced relation to the inner sleeve wall so as to provide an annular flow space about said needle valve and having a stem threaded in and extending beyond said opposite end of said inner sleeve, whereby said needle valve may be rotated to adjust the same toward and away from said valve seat, means on the outer end of said needle valve stem for rotating said needle valve, and means on the adjacent end of the outer sleeve for rotating the latter sleeve relative to the inner sleeve.