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Fuel vapor leak detection system

  • US 5,390,645 A
  • Filed: 03/04/1994
  • Issued: 02/21/1995
  • Est. Priority Date: 03/04/1994
  • Status: Expired due to Fees
First Claim
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1. A canister purge system comprising a collection canister for collecting volatile fuel vapors from a fuel tank, and means for selectively purging collected fuel vapors from said canister to an internal combustion engine'"'"'s intake manifold for entrainment with a combustible mixture that passes from the intake manifold into combustion chamber space of the engine for combustion therein, said means including a purge flow path between a purge port means of said canister and the intake manifold, said canister further having tank port means for communicating said canister with said fuel tank, characterized by an associated diagnostic system for detecting leakage from a portion of the canister purge system, including said canister and tank, when said portion is closed to conduct a leakage test, said diagnostic system comprising pump means for positively pressurizing said portion by conducting a first portion of the pump means flow through a first flow path from said pump means to said portion of the canister purge system and concurrently conducting a second portion of the pump means flow from said pump means through a second flow path containing a known orifice means, means for detecting the flow differential between that first portion of the pump means flow passing through said first flow path and that second portion of the pump means flow passing through said second flow path, and means for determining the leakage from the detected flow differential.

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