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System and method for measuring recirculated exhaust gas flow in a compression-ignition engine

  • US 6,347,519 B1
  • Filed: 08/17/2000
  • Issued: 02/19/2002
  • Est. Priority Date: 03/31/2000
  • Status: Expired due to Term
First Claim
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1. A system for measuring the mass flow rate of recirculated exhaust gas in a vehicle having a compression-ignition engine, a plurality of engine sensors having outputs indicative of current engine conditions including an intake manifold pressure sensor, and a variable geometry turbocharger in which geometry is varied by a controllable actuator, the system comprising:

  • an exhaust gas recirculation valve mounted in the engine exhaust line for controllably diverting a selected portion of the exhaust gas for mixture with intake air;

    a temperature sensor mounted in the flow path of the recirculated exhaust gas;

    an obstruction in the flow path of the recirculated exhaust gas;

    a differential pressure sensor including a first pressure tap located for sensing the pressure of the recirculated exhaust gas upstream of the obstruction, and a second pressure tap located for sensing the pressure of the recirculated exhaust gas downstream of the obstruction; and

    control logic for determining flow rate of the recirculated exhaust gas as a function of the current intake manifold pressure, recirculated exhaust gas temperature, and differential pressure drop across the obstruction.

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