Exhaust purification system of an internal combustion engine

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EP 1 515 029 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	07.06.2006 Bulletin 2006/23

(43)	Date of publication A2:
	16.03.2005 Bulletin 2005/11

(21)	Application number: 04021239.1

(22)	Date of filing: 07.09.2004

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International Patent Classification (IPC):

F02D 41/02^(2006.01)

F01N 3/08^(2006.01)

(84)	Designated Contracting States:
	AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PL PT RO SE SI SK TR
	Designated Extension States:
	AL HR LT LV MK

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Priority:

12.09.2003 JP 2003321408

(71)	Applicant: Toyota Jidosha Kabushiki Kaisha
	Toyota-shi, Aichi-ken 471-8571 (JP)

(72)	Inventors:
	Kobayashi, Nobuki Toyota-shi Aichi-ken, 471-8571 (JP) Sugiyama, Tatsumasa Toyota-shi Aichi-ken, 471-8571 (JP) Tahara, Jun Toyota-shi Aichi-ken, 471-8571 (JP)

(74)	Representative: Kuhnen & Wacker
	Patent- und Rechtsanwaltsbüro Prinz-Ludwig-Strasse 40A 85354 Freising 85354 Freising (DE)

(54)	Exhaust purification system of an internal combustion engine

(57) In an exhaust purification system of an internal combustion engine (1) that includes a NOx catalyst (16) for occluding and reducing NOx in exhaust, when removing SOx deposited in the NOx catalyst, a concentration of sulfur in a fuel is detected, and an amount of SOx deposited in the NOx catalyst is estimated taking into consideration the concentration of sulfur in the fuel. Further, an air-fuel ratio of exhaust flowing into the NOx catalyst (16) is changed to a richer side air-fuel ratio depending on a decrease in the estimated SOx amount, thereby adjusting an HC concentration of exhaust flowing out from the NOx catalyst (16) to a level equal to or less than a permissible HC concentration.

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