Carburetor for automotive vehicles

Claim 1

In a carburetor for automotive engines comprising means for admixing fuel-air mixtures for normal engine operation, including a primary fuel system having an admixture suction outlet passageway; a selectively actuatable mixing throttle positioned in said passageway; means for admixing fuel-air mixtures for idling and motive engine operation including a calibrated fuel inlet orifice, a calibrated air inlet jet means, and an auxiliary and idling secondary fuel-air mixture inlet passageway joining into said primary fuel system outlet passageway downstream of said throttle; the improvement comprising, regulating valve means interposed in said secondary fuel-air mixture inlet passageway at the outlet end thereof, said valve having a variable-area flow passageway, actuating means for said regulating valve, said actuating means including a closed housing, a flexible membrane in said housing dividing the latter into first and second chambers, means venting said first chamber tO atmospheric air, means forming a reduced-pressure passageway connecting said second chamber to said primary fuel system suction outlet passageway downstream of said mixing throttle, resilient spring means in said housing, said membrane being biased in opposition to the tensile force of said spring means in response to the reduced pressure in said suction outlet passageway, a return valve, said return valve being positioned in the reduced-pressure passageway interconnecting said housing with said suction outlet passageway, said return valve limiting flow in the direction toward said housing when the pressure in said reduced-pressure passageway exceeds the pressure in said housing, a by-pass conduit bridging said return valve, said by-pass conduit effecting continuous flow communication between said reducedpressure passageway and said second membrane chamber, and a selector valve disposed in the passageway interconnecting said reduced-pressure passageway and said primary system suction outlet passageway downstream of said mixing throttle, said selector valve alternatively connecting the reduced-pressure passageway with the suction outlet passageway and with the ambient surrounding air, the valve flow area adapted to be automatically increased responsive to pressure increases in said primary system suction outlet passageway, and decreased responsive to pressure drops in said outlet passageway.