Hitachi, Ltd.

Youichi Iihoshi

Nobuyasu Kanekawa

Toshiharu Nogi

Atsushi Shimada

Toshio Hori

Shinji Nakagawa

Shiro Yamaoka

Yoshikuni Kurashima

Shiro Yamoaka

The invention provides an engine controller, which can determine a deterioration mode (gain deterioration or response deterioration) of an air/fuel (A/F) ratio sensor, can detect a degree of the deterioration with high accuracy, and can optimize A/F ratio feedback control in accordance with the diagnosis result. The controller includes a unit for computing frequency response characteristics in a range from an A/F ratio adjusting unit to the A/F ratio sensor, and it diagnoses the A/F ratio sensor based on a gain characteristic and a response characteristic given by the computed frequency response characteristics. In accordance with the diagnosis result, parameters (P- and I-component gains) used in A/F ratio feedback control (PI control) are optimized.

Engine controller

In a multi-cylinder engine having a compression ignition combustion mode, a vibration detecting sensor that is preferably mounted in a cylinder block or a cylinder head is used to detect a frequency and the detected frequency is appropriately analyzed to detect or estimate a cylinder pressure peak value and peak timing for each cylinder. An amount of internal EGR, a fuel injection condition, an engine speed and the like are then controlled so as to bring each of these parameters into an appropriate range thereof. The control apparatus suppresses variations in combustion states among different cylinders and different cycles arising from unit-to-unit variations or deterioration in the engine or part-to-part variations or deterioration in a component thereof.

Control apparatus and control method for multi-cylinder engine

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Tsuchiura, Japan

Youichi Iihoshi