Leakage diagnosis apparatus for fuel vapor purge system and method thereof
First Claim
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1. A leakage diagnosis apparatus for a fuel vapor purge system, in which fuel vapor generated in a fuel tank is trapped in a canister via an evaporation passage, and the fuel vapor trapped in said canister is purged, via a purge passage, into an intake passage of an internal combustion engine, comprising:
- a blocking device blocking a diagnosis zone containing at least one of said fuel tank, said evaporation passage, said canister and said purge passage;
a pressure generator changing a pressure in said diagnosis zone;
a pressure detector detecting the pressure in said diagnosis zone; and
a diagnosis unit that blocks said diagnosis zone by said blocking device to change the pressure in said blocked diagnosis zone by said pressure generator, and diagnoses an occurrence of leakage in said diagnosis zone based on the pressure detected by said pressure detector, wherein said diagnosis unit obtains a curvature of change curve of said pressure, and diagnoses an occurrence of leakage based on the comparison between said curvature and a threshold.
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Abstract
In a fuel vapor purge system, a blocked diagnosis zone is pressurized by an air pump, a pressure in the diagnosis zone at the time when the diagnosis zone is pressurized, and an occurrence of leakage in the diagnosis zone is judged based on the comparison between a curvature of a change curve of the pressure and a threshold.
18 Citations
23 Claims
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1. A leakage diagnosis apparatus for a fuel vapor purge system, in which fuel vapor generated in a fuel tank is trapped in a canister via an evaporation passage, and the fuel vapor trapped in said canister is purged, via a purge passage, into an intake passage of an internal combustion engine, comprising:
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a blocking device blocking a diagnosis zone containing at least one of said fuel tank, said evaporation passage, said canister and said purge passage;
a pressure generator changing a pressure in said diagnosis zone;
a pressure detector detecting the pressure in said diagnosis zone; and
a diagnosis unit that blocks said diagnosis zone by said blocking device to change the pressure in said blocked diagnosis zone by said pressure generator, and diagnoses an occurrence of leakage in said diagnosis zone based on the pressure detected by said pressure detector, wherein said diagnosis unit obtains a curvature of change curve of said pressure, and diagnoses an occurrence of leakage based on the comparison between said curvature and a threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A leakage diagnosis apparatus for a fuel vapor purge system, in which fuel vapor generated in a fuel tank is trapped in a canister via an evaporation passage, and the fuel vapor trapped in said canister is purged, via a purge passage, into an intake passage of an internal combustion engine, comprising:
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blocking means for blocking a diagnosis zone containing at least one of said fuel tank, said evaporation passage, said canister and said purge passage;
means for changing a pressure in said blocked diagnosis zone by an external pressure generating source;
means for detecting the pressure in said diagnosis zone;
means for calculating a curvature of a change curve of said pressure in said diagnosis zone in a state where the pressure in said diagnosis zone is being changed by said external pressure generating source; and
means for diagnosing an occurrence of leakage based on the comparison of said curvature and a threshold.
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13. A leakage diagnosis method for a fuel vapor purge system, in which fuel vapor generated in a fuel tank is trapped in a canister via an evaporation passage, and the fuel vapor trapped in said canister is purged, via a purge passage, into an intake passage of an internal combustion engine, comprising the steps of:
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blocking a diagnosis zone containing at least one of said fuel tank, said evaporation passage, said canister and said purge passage;
changing a pressure in said blocked diagnosis zone using an external pressure generating source;
detecting the pressure in said diagnosis zone;
calculating a curvature of a change curve of said detected pressure in said diagnosis zone; and
diagnosing an occurrence of leakage based on the comparison of said curvature and a threshold. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification