AIR-FUEL RATIO ESTIMATING UNIT FOR EACH ENGINE CYLINDER OF INTERNAL COMBUSTION ENGINE

Japanese Patent JP3162521

B2

PURPOSE: To estimate an air-fuel ratio with the use of a microcomputer or the like of an on-board ECU (electronic control unit) by setting upper and lower limits to a status variable so that the status variable is replaced with a predetermined value when it exceeds these limit values.
CONSTITUTION: An air-fuel ratio of each of engine cylinders is estimated in accordance with an instruction stored in a ROM 52 of a CPU 50 so as to compute a control value, and an injector 20 for each of the engine cylinders is driven by means of a drive circuit 66, and a solenoid valve 70 for each engine cylinder is driven by a second drive circuit 60 so as to control the volume of secondary air flowing through a bypass passage. At this time, an exhaust system model is built up in order to estimate air-fuel ratios of the respective engine cylinder from outputs of a signal air-fuel ratio provided in a manifold of an exhaust system, and a status equation and an output equation using the air-fuel ratios of the respective engine cylinders are obtained. Further, upper and lower limits are set to at least one of the status variables so that when the variable exceeds these limit values, this variable is replaced with a predetermined value between the limit values. With this arrangement, it is possible to ensure a minimum resolution, thereby it is possible to enable an on-board ECU or the like to estimate an air-fuel ratio of each of the engine cylinders.

Yuusuke Hasegawa
Hidetaka Maki

JP34969992A

May 08, 2001

December 02, 1992

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Honda motor industry stock company

F02D45/00; F02D41/00; F02D41/14; F02D41/34; (IPC1-7): F02D45/00

JP59110562A
JP62150047A
JP57102529A

Yutaka Yoshida (1 person outside)

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