초록 ▼

A fuel vapor purge system has a canister for adsorbing fuel vapor from a fuel tank, a bypass passage bypassing the canister, and a bypass valve for controlling the state of connection of the bypass passage to a purge passage. The bypass passage is provided with a venturi so that the flow passage res

A fuel vapor purge system has a canister for adsorbing fuel vapor from a fuel tank, a bypass passage bypassing the canister, and a bypass valve for controlling the state of connection of the bypass passage to a purge passage. The bypass passage is provided with a venturi so that the flow passage resistance of the bypass passage is normally greater than the flow passage resistance of the canister. The amount of flow of gas from an air chamber to an intake passage changes in accordance with the flow passage resistance of the passage. In this case, the tank internal pressure in the air chamber converges to a value corresponding to the flow passage resistance of the passage between the air chamber and the intake passage. Therefore, based on the tank internal pressure occurring before and after the supply of a drive signal to the bypass valve, it is determined whether the bypass passage has a clogged abnormality and whether the bypass valve has a fixation abnormality.

대표청구항 ▼

1. An abnormality diagnostic apparatus of a fuel vapor purge system, comprising:a fuel tank connectable in communication to an atmosphere; a main passage connecting the fuel tank and an intake passage of an internal combustion engine via a canister for adsorbing a fuel vapor from the fuel tank; a by

1. An abnormality diagnostic apparatus of a fuel vapor purge system, comprising:a fuel tank connectable in communication to an atmosphere; a main passage connecting the fuel tank and an intake passage of an internal combustion engine via a canister for adsorbing a fuel vapor from the fuel tank; a bypass passage connecting the fuel tank and the intake passage, bypassing the canister; changing means for selectively changing between the main passage and the bypass passage; pressure detecting means for detecting a pressure in the fuel tank; and abnormality determining means for determining whether there is an abnormality in at least one of the bypass passage and the changing means based on the pressure detected by the pressure detecting means before and after an operation of changing between the main passage and the bypass passage is performed while air is flowing from the fuel tank toward the intake passage.