FAILURE DIAGNOSTIC DEVICE IN EVAPORATED FUEL TREATMENT DEVICE

摘要

PURPOSE: To enable failure diagnosis to be performed whenever necessary by performing failure diagnosis through the comparison of estimated pressure based on a signal output from a valve control means with pressure detected by a pressure detection means, the pressure estimated according to the operating condition of a purge control valve caused by the signal output from the valve control means. ;CONSTITUTION: Under normal conditions in which no vapor leaks and a purge control valve 6 functions properly, pressure within a purge line 3 between a canister C and the purge control valve 6 should be positive pressure equal to or greater than atmospheric pressure when the purge control valve 6 is closed, and be negative pressure equal to or greater than a predetermined value when the purge control valve 6 is opened. Pressure detected by a pressure detection means 8 connected to the purge line 3 and a signal output from a valve control means 10 controlling the opening and closing action of the purge control valve 6 are input to a failure diagnostic means 11, where judgement on failure is made based on comparison of pressure estimated according to whether the purge control valve 6 is open or closed with a detection signal of the pressure detection means 8.;COPYRIGHT: (C)1996,JPO