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Exhaust purification device of internal combustion engine

  • US 5,450,722 A
  • Filed: 02/14/1994
  • Issued: 09/19/1995
  • Est. Priority Date: 06/12/1992
  • Status: Expired due to Term
First Claim
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1. An exhaust purification device of an internal combustion engine comprising:

  • an engine exhaust passage;

    an NOx absorbent disposed within the engine exhaust passage, wherein the NOx absorbent absorbs NOx included in exhaust gas from the engine when the air-fuel ratio of the exhaust gas flowing into the NOx absorbent is lean and wherein the NOx absorbent releases the absorbed NOx when the air-fuel ratio of the exhaust gas flowing into the NOx absorbent becomes rich;

    temperature detecting means for detecting a temperature representing the temperature of the NOx absorbent; and

    NOx release controlling means for making the air-fuel ratio of the exhaust gas flowing into the NOx absorbent a predetermined rich air-fuel ratio for a predetermined period of time when the NOx is to be released from the NOx absorbent and wherein the NOx release controlling means determines one of the predetermined rich air-fuel ratio and the predetermined period of time based on the temperature of the NOx absorbent, so that, when the NOx release controlling means determines the predetermined rich air-fuel ratio based on the temperature of the NOx absorbent, the predetermined rich air-fuel ratio is made richer as the temperature of the NOx absorbent increases and, when the NOx release controlling means determines the predetermined period of time based on the temperature of the NOx absorbent, the predetermined period of time is shortened as the temperature of the NOx increases.

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