Foley & Lardner
Exhaust emission control device
 A three-way catalytic converter is provided in the exhaust passage of an engine. An HC trap type catalytic converter which acts as an HC trap and which has a greater oxygen storage capacity than the three-way catalytic converter is disposed downstream of the three-way catalytic converter. It is necessary to create a super-oxygenated atmosphere above an HC emission temperature in order to release HC which has been absorbed by the HC trap type catalytic converter. Since the oxygen storage capacity of the three-way catalytic converter is low, a super-oxygenated atmosphere is immediately created in the HC trap type catalytic converter by varying the air-fuel ratio to a lean air-fuel ratio. 
Nissan Motor Co., Ltd.
F B Y F F F F B
F01N B01D Y02T F01N F01N F01N F02D B01D
inventional inventional additional inventional inventional inventional inventional inventional
Mikio Ritsuo Fuminori Kimiyoshi
Tsuzuki Sato Yamanashi Nishizawa