Patent Document ID: 4854287
Application ID: 07098038
Patent Flag: 1

Claim One:
1. An apparatus for learning and controlling an air/fuel ratio in an internal combustion engine comprising: engine driving state detecting means for detecting an engine driving state including at least one area and at least one parameter having an impact on quantity of air sucked into said engine; air/fuel ratio detecting means for detecting an exhaust component of said engine and thereby detecting said air/fuel ratio in an air/fuel mixture sucked in said engine; basic fuel injection quantity setting means for setting a basic fuel injection quantity based on said parameter detected by said engine driving state detecting means; rewritable altitude learning correction coefficient storing means which stores therein an altitude learning correction coefficient for indiscriminately correcting said basic fuel injection quantity set by said basic fuel injection quantity setting means for all of said areas of said engine driving state based on the altitude at which said engine is located; rewritable area-wise learning correction coefficient storing means which stores therein an area-wise learning correction coefficient for correcting said basic fuel injection quantity for respective areas of said engine driving state; area-wise learning correction coefficient retrieving means for retrieving an area-wise learning correction coefficient for a corresponding area of said engine driving state from said area-wise learning correction coefficient storing means based on actual engine driving state; feedback correction coefficient setting means for comparing said air/fuel ratio detected by said air/fuel ratio detecting means with a desired air/fuel ratio while said engine is driven in a predetermined driving state and adjusting by a predetermined quantity a feedback correction coefficient for correcting said basic fuel injection quantity to bring actual air/fuel ratio close to said desired air/fuel ratio; fuel injection quantity computing means for computing said fuel injection quantity based on said basic fuel injection quantity set by said basic fuel injection quantity setting means, said altitude learning correction coefficient stored in said altitude learning correction coefficient storing means, said area-wise learning correction coefficient retrieved by said area-wise learning correction coefficient retrieving means and said feedback correction coefficient set by said feedback correction coefficient setting means; fuel injection means for injecting and supplying a fuel to said engine in an on-off manner according to a driving pulse signal corresponding to said fuel injection quantity computed by said fuel injection quantity computing means; deceleration driving state detecting means for detecting a deceleration driving state of said engine; deceleration proportion computing means for computing a deceleration proportion which is a proportion of a deceleration driving state period or number in a predetermined period based on said deceleration driving state detected by said deceleration driving state detecting means; altitude learning correction coefficient modifying means for modifying and rewriting said altitude learning correction coefficient stored in said altitude learning correction coefficient storing means according to said deceleration proportion computed by said deceleration proportion computing means; and area-wise learning correction coefficient modifying means for learning deviation of the feedback correction coefficient from a reference value for said respective areas of the engine driving state and modifying and rewriting the area-wise learning correction coefficient of said area-wise learning correction coefficient storing means so as to reduce said deviation.