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Leakage diagnosis apparatus for fuel vapor purge system and method thereof

  • US 20050000273A1
  • Filed: 05/24/2004
  • Published: 01/06/2005
  • Est. Priority Date: 05/29/2003
  • Status: Active Grant
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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