Closed loop air-fuel ratio control system

摘要

A command signal drives a carburetor metering valve to provide the carburetor fuel flow which will establish a desired air-fuel ratio; simultaneously, the command signal drives a control unit which purges fuel vapor from a fuel vapor storage region. The control unit minimizes purge flow when either maximum fuel flow or minimum fuel flow is commanded and maximizes purge flow when an intermediate fuel flow is commanded; accordingly, fuel vapor is purged from the vapor storage region only when the purge flow cannot unduly enrich or unduly lean the mixture.