Device and method for diagnosing evaporation leak, and control device of internal combustion engine

An evaporation leak diagnostic device for detecting a fuel vapor leak in an internal combustion engine having an evaporation purge system that includes a fuel tank and a communicating tube, which connects a canister for adsorbing and retaining fuel vapor to an intake pipe, the evaporation leak diagnostic device comprising:

• pressure detection means for detecting the pressure of the evaporation purge system;
• shutout means for shutting out the evaporation purge system from atmospheric air;
• a pump for pressurizing or depressurizing the evaporation purge system;
• and
• leak judgment means comprising a control unit which drives the pump for a predetermined period of time while the shutout means shuts out the evaporation purge system from atmospheric air, and formulates a leak judgment in accordance with the amount of pressure change that the pressure detection means detects during the time the pump is driven, and the amount of pressure change during a predetermined period of time after pump stoppage.

An evaporation leak diagnostic method for detecting a fuel vapor leak in an internal combustion engine having an evaporation purge system that includes a fuel tank and a communicating tube, which connects a canister for adsorbing and retaining fuel vapor to an intake pipe, the evaporation leak diagnostic method comprising the steps of:

• causing pressure detection means to detect the pressure of the evaporation purge system;
• causing shutout means to shut out the evaporation purge system from atmospheric air;
• driving a pump for pressurization or depressurization purposes while the shutout means shuts out the evaporation purge system from atmospheric air;
• stopping the pump when the pressure detected by the pressure detection means reaches a predetermined level;
• and
• formulating a leak judgment in accordance with the drive time for the pump and a pressure change encountered after pump stoppage.

An evaporation leak diagnostic method for detecting a fuel vapor leak in an internal combustion engine having an evaporation purge system that includes a fuel tank and a communicating tube, which connects a canister for adsorbing and retaining fuel vapor to an intake pipe, the evaporation leak diagnostic method comprising the steps of:

• causing pressure detection means to detect the pressure of the evaporation purge system;
• driving a pump for a predetermined period of time to pressurize or depressurize the evaporation purge system while shutout means shuts out the evaporation purge system from atmospheric air;
• and
• formulating a leak judgment in accordance with the amount of pressure change that is detected by the pressure detection means during the time the pump is driven and the amount of pressure change during a predetermined period of time after pump stoppage.