METHOD FOR CHECKING LEAK OF FUEL IN FUEL TANK

摘要

The present invention relates to a device for detecting a fuel leak from a fuel tank by opening and closing a purge valve formed on a flow passage to an engine from a canister and a blocking valve which is formed on a flow passage to the air from the canister. The device for detecting a fuel leak from the fuel tank includes a first step which forms the inner pressure of the fuel tank lower than air pressure by opening the purge valve and closing the blocking valve when an engine is driving; a second step which increases the inner pressure of the fuel tank by closing the purge valve and opening the blocking valve when the inner pressure of the fuel tank is lower than preset first pressure after the engine stops; a third step which lowers the inner pressure of the fuel tank by maintaining the opened state of the purge valve and closes the blocking valve again when the inner pressure of the fuel tank is higher than preset second pressure; and a fourth step which detects the fuel leak from the fuel tank based on a grade which the inner pressure of the fuel tank is increased while maintaining the inner pressure of the fuel tank within a predetermined range by repeating the second and third steps. The device for detecting a fuel leak from the fuel tank controls the inner pressure of the fuel tank by using the blocking valve, thereby continuously detecting a fuel leak even though the purge valve is not operated because of a stop of the engine.