| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an evaporation system leakage diagnostic apparatus which distinctly diagnoses a canister and a fuel tank with one pressure sensor even while an internal combustion engine is stopped without adding a pump and a three-way valve to the evapo system. <P>SOLUTION: A leakage of the fuel tank is diagnosed, based on a tank internal pressure Pfg of a fuel tank air-tightly sealed with a blockade valve, according to whether the pressure is in the neighborhood of the atmospheric one (S106). When the fuel tank has no leakage (S106:NO), the blockade valve is opened in the state of a purge control valve and a CCV being closed so that the pressure in the fuel tank is introduced into the canister (S110, S112), and the leakage of the canister is diagnosed. In this diagnosis, the leakage diagnosis is made based on the tank internal pressure Pfg and its change before and after the pressure introduction. If the leakage exists in this diagnosis, it is determined that the leakage occurs in the canister. Even when the internal combustion engine is stopped, only with the tank internal pressure Pfg by using the internal pressure of the fuel tank, the leakage diagnosis is enabled, while the fuel tank and the canister are distinguished. <P>COPYRIGHT: (C)2012,JPO&INPIT |
