Air-fuel ratio regulator for internal combustion engine

Claim 1

An air-fuel ratio regulator for an internal combustion engine comprising a carburetor having an air passage comprising an air inlet, venturi, a throttle valve downstream of said venturi and an intake passage downstream of said throttle valve, a by-pass air passage leading from said air inlet to said intake passage, first control valve means in said by-pass air passage for opening and closing same, said control valve means comprising a valve member movable between an open position and a closed position, a valve stem for moving said valve member, spring means acting on said valve member to bias it to closed position, a differential pressure responsive means comprising a diaphragm disposed to act on said valve stem to move said valve member to open position, a first vacuum chamber on one side of said diaphragm, a second vacuum chamber on the opposite side of said diaphragm, said vacuum chambers being so disposed that said diaphragm is moved in a direction to open said valve means when pressure in said second vacuum chamber is higher than pressure in said first vacuum chamber, first passage means connecting said first vacuum chamber directly with said intake passage, second passage means comprising a restricted orifice and a check valve connected in parallel with one another connecting said second vacuum chamber with said intake passage, said check valve being disposed to permit flow only from said first vacuum chamber to said second vacuum chamber, third passage means leading from said second vacuum chamber to the atmosphere and second control valve means in said third passage means, said second control valve means being responsive to specific operating conditions of the engine to apply atmospheric air pressure to said second vacuum chamber.