| 摘要 |
PURPOSE: An apparatus for purifying an exhaust gas for an internal combustion engine is provided to enhance a purifying efficiency of the exhaust gas by recirculating the exhaust gas when a cold starting before catalyst is activated and by activating a catalyst reaction by introducing a secondary air simultaneously. CONSTITUTION: An apparatus for purifying an exhaust gas comprises a catalyst converter(1) for purifying the exhaust gas by a catalyst(2), a secondary air supplying device(5), an exhaust gas circulating pipe(14), and an exhaust gas switching thermocouple(16). During an initial starting of the engine, an external air is introduced by the secondary air supplying device(5) using a negative pressure effect due to discharging of the exhaust gas to increase oxygen concentration of the exhaust gas introduced to the catalyst(2). Upon a cold starting of the engine, the exhaust gas through passing the catalyst is recirculated to a front inlet of the catalyst(2) by the exhaust gas pipe(14). At non-activating state of the catalyst, the exhaust gas switching thermocouple(16) is operated by a thermal deformation, so that the exhaust gas passed through the catalyst is not discharged to a backward and is recirculated through the exhaust gas circulating pipe(14).
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