Method of controlling an air-fuel ratio of an engine

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(11)

EP 0 811 758 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	01.09.1999 Bulletin 1999/35

(43)	Date of publication A2:
	10.12.1997 Bulletin 1997/50

(21)	Application number: 97108963.6

(22)	Date of filing: 04.06.1997

(51)	International Patent Classification (IPC)⁶: F02D 41/14

(84)	Designated Contracting States:
	AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

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Priority:

04.06.1996 JP 141763/96
04.06.1996 JP 141882/96

(71)	Applicant: TOYOTA JIDOSHA KABUSHIKI KAISHA
	Aichi (JP)

(72)	Inventor:
	Shibagaki, Nobuyuki Toyota-shi, Aichi (JP)

(74)	Representative: Kügele, Bernhard et al
	NOVAPAT INTERNATIONAL SA, 9, Rue du Valais 1202 Genève 1202 Genève (CH)

(54)	Method of controlling an air-fuel ratio of an engine

(57) In an engine, the elapsed time for rotation through 30 degrees crank angle near top dead center of the compression stroke and the elapsed time for rotation through 30 degrees crank angle near 90 degrees after top dead center of the compression stroke are found and the amount of torque fluctuation is found from these elapsed times. Whether the vehicle is driving on a rough road is judged from the amount of fluctuation of the angular velocity of the crankshaft. When it is judged that the vehicle is driving on a rough road, the correction of the air-fuel ratio based on the amount of torque fluctuation is prohibited.

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