Failure diagnostic apparatus for fuel vapor purge system and fuel vapor purge apparatus and combustion engine having failure diagnostic apparatus
AssigneesToyota Jidosha Kabushiki Kaisha, Denso Corporation
InventorsHideki Miyahara, Tokiji Ito, Kenji Nagasaki
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Abstract
After a reference pressure using a reference hole is measured, a pressure in an evaporation path is measured. An ECU conducts failure diagnosis using, as a determination pressure for diagnosing presence/absence of a failure, a value obtained by correcting the reference pressure using the reference hole in a manner lowering the same by a predetermined amount, taking into account pressure lowering in the evaporation path due to condensation of fuel vapor at the time of adsorption in a canister when a vapor concentration in the evaporation path is high.
Claims11
A failure diagnostic apparatus for a fuel vapor purge system adsorbing in a canister fuel vapor generated in a fuel tank and purging the adsorbed fuel vapor into an intake system, comprising:
- pressure difference generation means for generating, when failure diagnosis is executed, a pressure difference between respective pressures inside and outside a fuel vapor path including said fuel tank and said canister;
- failure diagnostic means for comparing, with a predetermined determination pressure, the pressure inside said fuel vapor path when said pressure difference generation means generates said pressure difference, for conducting said failure diagnosis to determine whether failure occurs or not based on result of the comparison;
- and
- correction means for correcting said predetermined determination pressure in a manner lowering said predetermined determination pressure when a concentration of the fuel vapor within said fuel vapor path is higher than a predetermined value.
A failure diagnostic apparatus for a fuel vapor purge system adsorbing in a canister fuel vapor generated in a fuel tank and purging the adsorbed fuel vapor into an intake system, comprising:
- pressure difference generation means for generating, when failure diagnosis is executed, a pressure difference between respective pressures inside and outside a fuel vapor path including said fuel tank and said canister;
- failure diagnostic means for comparing, with a predetermined determination pressure, the pressure inside said fuel vapor path when said pressure difference generation means generates said pressure difference, for conducting said failure diagnosis to determine whether failure occurs or not based on result of the comparison;
- and
- correction means for correcting a measured pressure value within said fuel vapor path in a manner increasing said measured pressure value when a concentration of the fuel vapor within said fuel vapor path is higher than a predetermined value.
A failure diagnostic apparatus for a fuel vapor purge system adsorbing in a canister fuel vapor generated in a fuel tank and purging the adsorbed fuel vapor into an intake system, comprising:
- pressure difference generation means for generating, when failure diagnosis is executed, a pressure difference between respective pressures inside and outside a fuel vapor path including said fuel tank and said canister in accordance with a drive command;
- failure diagnostic means for comparing, with a predetermined determination pressure, the pressure inside said fuel vapor path when said pressure difference generation means generates said pressure difference, for conducting said failure diagnosis to determine whether failure occurs or not based on result of the comparison;
- and
- correction means for correcting said drive command for said pressure difference generation means in a manner lowering said pressure difference generated by said pressure difference generation means when a concentration of the fuel vapor within said fuel vapor path is higher than a predetermined value.
Dependencies are inferred from the claim text.