Controller for controlling an evaporated fuel amount to be purged

Abstract

An evaporated fuel controller for an internal-combustion engine comprises a purge system for purging evaporated fuel generated inside a fuel tank to an intake system of the engine. The controller determines a guard value in accordance with driving conditions of the engine. The guard value is an upper limit of the evaporated fuel. The purge control valve is controlled to prevent the amount of the evaporated fuel from exceeding the guard value. Thus, the amount of the evaporated fuel is controlled so that influence on the air-fuel ratio control is minimized. In one embodiment, the controller further determines a transport lag of the evaporated fuel between the purge control valve and the engine. The controller determines an evaporated fuel amount purged a time period earlier, the time period corresponding to the transport lag. The purge control valve is controlled to prevent the amount of the evaporated fuel from increasing if the evaporated fuel amount purged the time period earlier is close to the guard value.

Dependencies are inferred from the claim text.