Evaporative emission control device of an internal combustion engine for vehicle use

摘要

An improved evaporative emission control device of an internal combustion engine having a variable venturi type carburetor which is effective to reduce unburnt components in the exhaust gas over the entire range of engine operation. Fuel vaporized in a fuel tank, a float chamber or the like and stored in a canister containing activated charcoal is supplied to an intake passage of the carburetor through a supply port which opens into the intake passage at a location between a throttle valve and a venturi valve which is disposed in the intake passage to vary the opening area of the venturi. A valve is disposed in a line connecting the supply port and the canister to control fuel vapor passing through the line. The valve is controlled to open and close in response to the operations of a clutch and/or a transmission device interposed in a power transmission system for conducting power from the engine to driving wheels.