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:
Nov. 15, 1994
Filed:
Feb. 10, 1993
Toshio Takaoka, Toyota, JP;
Toyota Jidosha Kabushiki Kaisha, Toyota, JP;
Abstract
An apparatus for controlling an air-fuel ratio in a lean burn internal combustion engine, such that three different air-fuel ratio zones are set, the three zones being an ultra lean zone with a low load, a medium lean zone with a medium load, and a non-lean zone with a high load. When the engine is under low load conditions, a map FLEANPM is selected to obtain an ultra lean air-fuel ratio based on detected intake pressure PM values and engine speed NE. When the engine is under medium load conditions, a map FLEANTA is selected to obtain a medium lean air-fuel ratio based on a detected throttle opening values TA and engine speed NE. When the engine is under high load, conditions the lean correction control is canceled, thereby obtaining a theoretical air-fuel ratio or an air-fuel ratio smaller than the theoretical air-fuel ratio, and when the engine remains at a point in the medium lean zone, the air-fuel ratio decreases gradually toward the theoretical air-fuel ratio as time elapses.