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Evaporated fuel treatment apparatus for internal combustion engine

  • US 6,354,143 B1
  • Filed: 02/02/2000
  • Issued: 03/12/2002
  • Est. Priority Date: 02/05/1999
  • Status: Expired due to Fees
First Claim
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1. An evaporated fuel treatment apparatus for an internal combustion engine having a fuel tank, a canister having an opening to the atmosphere, the opening being opened or closed by a vent shut valve, a passage allowing the fuel tank to communicate with the canister, a purging passage allowing the canister to communicate with the intake manifold of the engine, the intake manifold having a reduced pressure as the engine intakes air, and a pressure sensor for detecting the internal pressure of the fuel tank, said apparatus comprising:

  • tank leak checking means that closes the tank after placing the tank under a negative pressure and detects the conditions of change in the internal pressure of the fuel tank for a predetermined period, pressure variation checking means that opens the fuel tank to the atmosphere after the predetermined period and judges whether or not the pressure inside the fuel tank has dropped, and judgment prohibition means that prohibits a judgment of the presence or absence of leakage based on the detection results obtained by the tank leak checking means if the pressure variation checking means judges that the pressure of the fuel tank has dropped.

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