Patent ID: 6095121
Filing Date: 2000-08-01
Classification: F02D,F02M

Abstract:
An evaporated fuel treatment device for an engine provided with an intake passage, comprising:a fuel vapor purge passage connecting an upper space of a fuel tank and the intake passage;a purge control valve arranged in the purge passage;air-fuel ratio detecting means for detecting an air-fuel ratio;first fuel supply correcting means for controlling an amount of fuel supply based on an air-fuel ratio detected by the air-fuel ratio detecting means so that an air-fuel ratio approaches a target air-fuel ratio;vapor concentration calculating means for calculating an intake passage vapor concentration of fuel vapor supplied to the intake passage based on an amount of deviation of the air-fuel ratio from the target air-fuel ratio;second fuel supply correcting means for further correcting the amount of fuel supply based on the intake passage vapor concentration so that the air-fuel ratio approaches the target air-fuel ratio; andconcentration change detecting means for detecting, while a purge operation is stopped, a change of a purge system vapor concentration of fuel vapor in one of the upper space of the fuel tank and a portion of the purge passage extending between the upper space of the fuel tank and the purge control valve, one of the first fuel supply correcting means and the second fuel supply correcting means correcting the amount of fuel supply in accordance with the detected concentration change so that the air-fuel ratio immediately after a restart of the purge operation becomes the target air-fuel ratio.