Patent ID: 6460330
Filing Date: 2002-10-08
Classification: F01N,F02B,F02D,F02M,Y02T

Abstract:
An engine intake A/F ratio control system in an outboard engine which includes an engine disposed in an engine room defined by an engine support connected to an upper portion of an extension case by an engine cover covering said engine support, and a catalytic converter incorporated in an exhaust system for the engine, wherein an exhaust gas exiting from said exhaust system is discharged under external water surface via an inside of said extension case,characterized in that said engine intake A/F ratio control system comprises a secondary air passage connected to a carburetor provided in an intake system for the engine for supplying secondary air for regulating the A/F ratio of an air-fuel mixture produced in the carburetor; a duty control unit connected to a duty control valve connected to said secondary air passage for controlling the duty ratio of a pulse applied to a coil of said duty control valve; and an LAF sensor mounted to said exhaust system for detecting an A/F ratio of an exhaust gas flowing through said exhaust system, thereby outputting a detection signal proportional to said A/F ratio to said duty control unit.