CANISTER PURGE METHOD IN FFV, AND CANISTER PURGE MECHANISM IN FFV USING SAID METHOD

摘要

In an FFV (flex fuel vehicle) mounted with an internal combustion engine using an alcohol-mixed fuel, the remaining amount of fuel vapor (i.e. the estimated amount remaining in a canister after normal purge treatment) is estimated on the basis of the alcohol concentration in the alcohol mixed fuel. Depending on the remaining amount, either a canister throttle control means adjusts the openness of a tank-side fluid path, which is the fluid path in the canister near a portion connecting with the passage connected to the fuel tank (the tank line), and / or, a variable valve timing mechanism changes the timing of the opening and closing of an intake valve. By this means, the desorption rate (desorption amount) of the fuel vapor from the adsorption material in the canister is adjusted and the concentration of fuel contained in the purge gas is adjusted. As a result, discharge of harmful substances can be suppressed and air-fuel ratio control can be made more accurate in said FFV, even given non-uniform concentration distributions of alcohol components in the canister or changes in the remaining amount of fuel vapor adsorbed by the adsorption material in the canister.