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.

Date of Patent:
Aug. 20, 2002

Filed:

Dec. 15, 2000
Applicant:
Inventors:

Shinichi Kitajima, Wako, JP;

Atsushi Matsubara, Wako, JP;

Asao Ukai, Wako, JP;

Hideyuki Takahashi, Wako, JP;

Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
F02B 7/508 ;
U.S. Cl.
CPC ...
F02B 7/508 ;
Abstract

The present invention increases the frequency of the LAF sensor deterioration determination in the case that air-fuel ratio control is being carried out while the deterioration of the LAF sensor is being monitored. When the monitor conditions are no longer satisfied during the deterioration determination of the LAF sensor (as shown in (a) and (b) of FIG. ), the LAF prohibition timer is operated (as shown in (c) of FIG. ), and switching to a lean burn is prohibited for a predetermined time interval (for example, 7 seconds), and in addition, after the LAF sensor deterioration determination has completed, after passage of a time interval shorter than this predetermined time interval (for example, 2 seconds) (as shown in figures (c) and (d) of FIG. ), a lean burn is permitted. Thereby, in the case that monitor conditions are no longer satisfied during monitoring, because the lean burn is prohibited, unlike conventional technology, there is no immediate switch to a lean burn, and therefore, the frequency of the deterioration determination of the LAF sensor can be increased.


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