System for controlling vaporized fuel in an internal combustion engine

Claim 1

An internal combustion engine comprising an engine body; an intake system connected to the engine body; a throttle valve arranged in the intake system; fuel passageway means opened to the intake system at a position downstream of the throttle valve in its idle position; a canister provided therein with a layer for absorbing vaporized fuel, said canister having a purge air inlet on one side of the layer and a purge air outlet on the other side of the layer; second passageway means for connecting the outlet of the canister with the intake system at a position always downstream of the throttle valve; purge control valve means for controlling the introduction of vaporized fuel from the canister to the engine; fuel-cut valve means for controlling the introduction of fuel from the fuel passageway to the engine; fuel-cut means responsive to a predetermined deceleration condition of the engine for operating the fuel-cut valve means so that the fuel passageway means are closed, including first sensor means for detecting a predetermined degree of throttle opening corresponding to the idle condition of the engine, second sensor means for detecting an engine speed lower than a predetermined value, and a first gate means responsive to signals from the first and the second sensor means for operating the fuel-cut valve means to close the fuel passageway means when the throttle opening is smaller than the predetermined degree while the engine speed is higher than the first predetermined value; and operating mens for closing the purge control valve means to prevent the introduction of vaporized fuel when the fuel is cut by the fuel-cut means and for opening the purge control valve means in accordance with the operating conditions, including at least engine speed, when the fuel is not cut.