Patent ID: 6082337
Filing Date: 2000-07-04
Classification: F02M

Abstract:
An abnormality diagnosis apparatus of an evaporated gas purge system for diagnosing abnormality of an evaporated gas purge system in which evaporated gas produced by evaporating fuel in a fuel tank is absorbed to a canister and the evaporated gas absorbed to the canister is purged to an intake pipe of an internal combustion engine, said abnormality diagnosis apparatus of the evaporated gas purge system comprising:negative pressure introducing means for introducing a negative pressure (P1a) into an evaporated gas system which is from the fuel tank to a purge control valve by closing a canister closure valve installed between the canister and atmosphere and opening the purge control valve installed downstream from the canister when an abnormality diagnosis condition is established;hermetically sealing means for bringing an inside of the evaporated gas system into a hermetically-sealed state by closing the purge control valve after introducing the negative pressure; andabnormality diagnosing means for diagnosing abnormality of leakage of the evaporated gas system based on a pressure change (DPT1) in the evaporated gas system in a predetermined time period, during a time period where the inside of the evaporated gas system is hermetically-sealed by the hermetically sealing means after introducing the negative pressure, and a pressure (Pmin-Pmax) in the evaporated gas system, during the time period where the inside of the evaporated gas system is hermetically-sealed after introducing the negative pressure and at a predetermined timing after detecting the pressure change.