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Engine exhaust gas purification device

  • US 5,551,231 A
  • Filed: 11/23/1994
  • Issued: 09/03/1996
  • Est. Priority Date: 11/25/1993
  • Status: Expired due to Term
First Claim
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1. An exhaust gas purification device of an engine, comprising:

  • air-fuel mixture control means for making an air-fuel mixture burned in a combustion chamber of the engine a rich air-fuel mixture;

    a three way catalyst arranged in an exhaust passage of the engine;

    a NOx absorbent arranged in said exhaust passage downstream of said three way catalyst, said NOx absorbent absorbing NOx therein when an air-fuel ratio of exhaust gas flowing into said NOx absorbent is lean;

    first secondary air supply means for feeding secondary air into said exhaust passage upstream of said three way catalyst;

    second secondary air supply means for feeding secondary air into said exhaust passage between said three way catalyst and said NOx absorbent; and

    secondary air control means for controlling amounts of secondary air fed from said first secondary air supply means and said second secondary air supply means to maintain the air-fuel ratio of the exhaust gas flowing into said three way catalyst at a rich air-fuel ratio which is larger than an air-fuel ratio of said first mentioned rich air-fuel mixture and to maintain the air-fuel ratio of the exhaust gas flowing into said NOx absorbent at a lean air-fuel ratio.

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