US 6,474,148 B2Granted

Diagnostic apparatus for fuel vapor purge system

AssigneeToyota Jidosha Kabushiki Kaisha

InventorsNaoya Takagi, Mamoru Yoshioka, Yoshihiko Hyoudou

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Abstract

A diagnostic apparatus for a fuel vapor purge system is provided which includes a pressure sensor that measures a pressure in a fuel tank, and which conducts leak diagnosis of a purge path based on a change in the pressure in the fuel tank and an amount of fuel vapor generated in the fuel tank. The change in the pressure is measured after sealing the purge path while providing a difference between inside pressure and outside pressure of the purge path, and the amount of fuel vapor is measured after applying an atmospheric pressure to the purge path and sealing the purge path. The diagnostic apparatus further detects a predetermined state after starting application of the atmospheric pressure to the purge path, and determines that the purge path has reached an atmospheric pressure state upon. detection of the predetermined state. The amount of fuel vapor generated in the fuel tank is measured when it is determined that the purge path has reached the atmospheric pressure state.

Claims30

Dependent claims

A diagnostic apparatus for a fuel vapor purge system wherein fuel vapor generated in a fuel tank is trapped in a canister, and the fuel vapor trapped in the canister is purged into an intake passage of an internal combustion engine through a purge path including the fuel tank, the apparatus comprising:

a pressure sensor that measures a pressure of a space in the fuel tank;
a diagnosing unit that conducts leak diagnosis of the purge path based on a change in the pressure in the fuel tank and an amount of fuel vapor generated in the fuel tank, said change in the pressure being measured after sealing the purge path while providing a difference between inside pressure and outside pressure of the purge path, said amount of fuel vapor being measured after applying an atmospheric pressure to the purge path and sealing the purge path;
and
a determining unit that determines that the purge path has reached an atmospheric pressure state upon detection of a predetermined state after starting application of the atmospheric pressure to the purge path, wherein said diagnosing unit measures the amount of fuel vapor generated in the fuel tank when said determining unit determines that the purge path has reached the atmospheric pressure state.

1 more element

A method of diagnosing a fuel vapor purge system wherein fuel vapor generated a fuel tank is trapped in a canister and the fuel vapor trapped in the canister is purged into an intake passage of an internal combustion engine through a purge path including the fuel tank, the method comprising the steps of:

measuring a pressure of a space in the fuel tank;
measuring a change in the pressure in the fuel tank after sealing the purge path while providing a difference between inside pressure and outside pressure of the purge path;
measuring an amount of fuel vapor generated in the fuel tank after applying an atmospheric pressure to the purge path and sealing the purge path;
conducting leak diagnosis of the purge path based on the change in the pressure in the fuel tank and the amount of fuel vapor generated in the fuel tank;
and
detecting a predetermined state after starting application of the atmospheric pressure to the purge path, and determining that the purge path has reached an atmospheric pressure state upon detection of the predetermined state, wherein the amount of fuel vapor generated in the fuel tank is measured when it is determined that the purge path has reached the atmospheric pressure state.

3 more elements

Dependencies are inferred from the claim text.