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Exhaust gas purification device of internal combustion engine

  • US 20050262829A1
  • Filed: 06/02/2005
  • Published: 12/01/2005
  • Est. Priority Date: 06/23/1998
  • Status: Active Grant
First Claim
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1. An exhaust gas purification device of an internal combustion engine arranging a catalyst suitable for reduction of NOx in exhaust gas by ammonia in the presence of excess oxygen in an engine exhaust passage, said device comprising:

  • feeding means for feeding a liquid containing an ammonia generating compound to the catalyst;

    feed control means for controlling the amount of feed of the liquid, the catalyst storing inside it at least part of the ammonia generating compound contained in the liquid fed to the catalyst and having the function of causing the release of ammonia a little at a time from the ammonia generating compound stored in the catalyst along with the rise of temperature of the catalyst and reducing the NOx in the exhaust gas by the ammonia released;

    decision means for deciding if the temperature of the catalyst is in an ammonia generating compound storage region which stores the ammonia generating compound contained in the liquid fed to the catalyst inside the catalyst and releases almost no ammonia from the stored ammonia generating compound, or if the temperature of the catalyst is in an ammonia release region which causes the ammonia to be released a little at a time from the stored ammonia generating compound;

    an exhaust gas recirculation device for recirculating the exhaust gas in an intake passage;

    wherein, when it is decided by the decision means that the temperature of the catalyst is in the ammonia generating compound storage region, said exhaust gas recirculation device stops a recirculation action of the exhaust gas and said feed control means controls the amount of feed of the liquid so that the amount of the ammonia generating compound in the liquid becomes more than the equivalent ratio=1 required for reducing the NOx in the exhaust gas.

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