Method and an apparatus to control the temperature of an engine exhaust gas purifying device

摘要

The temperature of an exhaust gas purifying device is maintained within an optimum range by enriching an air-fuel mixture for the engine, retarding the ignition timing of the engine, supplying secondary air into engine exhaust gases fed to the purifying device and producing a spark therein when the temperature of the purifying device is below the minimum of the optimum range and by diluting the air-fuel mixture, advancing the engine ignition timing to a normal value, stopping supply of the secondary air and production of the spark when the temperature of the purifying device is higher than the maximum of the optimum range.