Oxygen sensor for internal combustion engine

Abstract

Abstract PURPOSE: To decrease nitrogen oxides by providing a reduction catalyst layer for the nitrogen oxides to accelerate the reduction reaction of the nitrogen oxides on the outside surface of a platinum catalyst layer so that lean detection is executed on the richer side as the concn. of the nitrogen oxides is higher. CONSTITUTION: An inside electrode 2 and outside electrode 3 respectively consisting of platinum are formed to part of the inside and outside surfaces of a ceramics pipe 1 and a platinum catalyst layer 4 is deposited by evaporation on the outside surface of the pipe 1. The reduction catalyst layer 5 in which catalyst particles are made to co-exist with titanium oxide, etc., as a carrier is formed on the outside surface of the layer 4. The layer 5 accelerates the reaction between the nitrogen oxides NOX and the unburned components CO and HC in an exhaust as when the NOX arrives at the layer 5. The concn. of O 2 increases correspondingly and the difference between the concn. of O 2 on the inside of the pipe 1 and the concn. of O 2 on the discharge side decreases. The leak detection is thus executed. The air-fuel ratio is, therefore, eventually controlled to the richer side as the concn. of NOX is higher if the feedback control of the air-fuel ratio is executed in accordance with the result of the detection. The increase in the amt. of the NOX to be discharged is thus suppressed. COPYRIGHT: (C)1989,JPO&Japio

Inventors

• 👤 Akira Uchikawa
• 👤 Satoshi Abe
• 👤 Masami Kawashima
• 👤 Tatsumasa Yamada

Bibliographic Details