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Exhaust Emission Control System

  • US 20180209316A1
  • Filed: 01/08/2018
  • Published: 07/26/2018
  • Est. Priority Date: 01/23/2017
  • Status: Active Grant
First Claim
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1. An exhaust emission control system, comprising:

  • a NOx storage catalyst provided in an exhaust passage of an engine and configured to store NOx;

    a urea selective catalytic reduction (SCR) catalyst provided in the exhaust passage downstream of the NOx storage catalyst; and

    a processor configured to execute a NOx reduction controlling module to set a NOx reduction condition and, when the NOx reduction condition is satisfied, perform NOx reduction processing in which an air-fuel ratio of exhaust gas is set to be one of near a stoichiometric air-fuel ratio and rich, and the NOx stored in the NOx storage catalyst is reduced, the NOx reduction condition being set looser for the NOx reduction processing performed a first time after the engine is started than the NOx reduction processing performed a second and subsequent times after the engine is started.

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