Patent ID: 6848298
Filing Date: 2005-02-01
Classification: F02M

Abstract:
1. A failure diagnosis apparatus of a fuel vapor purge system, the fuel vapor purge system including a fuel tank that stores fuel for an internal combustion engine, a canister that collects fuel vapor generated in the fuel tank, and an evaporation route that includes the fuel tank, the canister, an evaporation passage for introducing the fuel vapor generated in the fuel tank into the canister, and a purge passage for purging the fuel vapor collected in the canister into an intake passage of the internal combustion engine, the failure diagnosis apparatus comprising a controller that: controls a pressure difference applying unit to applying a pressure difference between the evaporation route and outside air; detects a level of an influence of the fuel vapor generated in the fuel tank on failure determination of the evaporation route; detects both a pressure state obtained when the pressure difference applying unit communicates with a reference orifice communicating with the outside air and a pressure state obtained when the pressure difference applying unit communicates with the evaporation route; determines whether there is a failure in the evaporation route in view of the level of the influence by comparing the former pressure state with the latter pressure; and determines whether a leak occurs when a pressure introducing set period does not elapse after the pressure becomes stable, wherein when a pressure difference application time to the evaporation route reaches a predetermined time, the controller determines whether there is a failure in the evaporation route regardless of the determination result that the pressure change in the evaporation route becomes stable.