The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 28, 2008
Filed:
Apr. 23, 2007
Shinji Nakagawa, Hitachinaka, JP;
Youichi Iihoshi, Tsuchiura, JP;
Yoshikuni Kurashima, Mito, JP;
Toshio Hori, Hitachinaka, JP;
Shinji Nakagawa, Hitachinaka, JP;
Youichi Iihoshi, Tsuchiura, JP;
Yoshikuni Kurashima, Mito, JP;
Toshio Hori, Hitachinaka, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
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.