Abnormality detecting apparatus for fuel evaporative emission control system of internal combustion engine

Abstract

An abnormality detecting apparatus for a fuel evaporative emission control system which ensures enhanced reliability includes a canister ( ) disposed in a purge passage, a purge control valve ( ), a control means ( ) for controlling opening/closing of the purge control valve ( ) in dependence on engine operation states, a means ( ) for detecting an intake pressure (Pb), a means for detecting at least one of an atmospheric pressure (PA), an outside air temperature (TG), an intake air temperature (TA) and a fuel temperature (TT), a means ( ) for detecting a fuel tank pressure (Pt), a means ( ) for determining validity of abnormality decision enabling conditions in the case where concentration of fuel gas is lower than a reference value for comparison, a means ( ) for regulating a purge rate in dependence on an intake pressure (Pb) when the abnormality decision enabling conditions are valid, a means ( ) for detecting occurrence of abnormality in the fuel evaporative emission control system on the basis of the fuel tank pressure (Pt) when the abnormality decision enabling conditions are valid, and a condition validation limiting means ( ) for correcting the comparison reference value in dependence on at least one of the atmospheric pressure (PA), the fuel temperature (TT), the outside air temperature (TG) and the intake air temperature (TA).