Patent ID: 7305975

Claim:
A method for controlling amounts of air and fuel introduced to an engine during purge of hydrocarbon vapor from a canister containing adsorbed hydrocarbon vapor, comprising the steps of: providing an initial value, C HC0 , for the concentration of hydrocarbon vapor in the canister containing adsorbed hydrocarbon vapor; drawing air into the canister containing adsorbed hydrocarbon vapor and withdrawing from the canister a volume of purge vapor containing desorbed hydrocarbon vapor; calculating a concentration of desorbed hydrocarbon vapor in the purge vapor; and using purge vapor volume and concentration of desorbed hydrocarbon vapor in the purge vapor to calculate the amounts of purge hydrocarbon vapor and purge air and adjusting an amount of fuel to be taken from the fuel tank and an amount of intake air based on the amounts of purge hydrocarbon vapor and purge air.