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Diagnostic device for exhaust gas recirculation system

  • US 7,104,259 B2
  • Filed: 03/22/2005
  • Issued: 09/12/2006
  • Est. Priority Date: 03/26/2004
  • Status: Expired due to Fees
First Claim
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1. A diagnostic device for an exhaust gas recirculation apparatus with an EGR valve disposed in a recirculation pipe interconnecting an exhaust pipe and an intake pipe downstream of a throttle valve, comprising:

  • EGR control means for selectively executing an EGR on-control to return an exhaust gas from said exhaust pipe to said intake pipe and an EGR off-control to cut off said return of said exhaust gas from said exhaust pipe to said intake pipe;

    diagnostic means for diagnosing a failure of said EGR system based on an intake pipe pressure during said EGR on-control and an intake pipe pressure during said EGR off-control when a diagnosis run condition is satisfied; and

    cancellation means for canceling diagnosis executed by said diagnostic means when said intake pipe pressure during the EGR off-control exceeds a presetted cancel determination value so as to easily and precisely perform to diagnose said failure.

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