Patent Number: 7,131,266

Title: Secondary air supply control apparatus for internal combustion engine

Abstract: When a specified air-fuel ratio F/B control condition is established during supply of a secondary air provided, an air-fuel ratio F/B control is executed, and at this time, an initial value of a target air-fuel ratio is set to a before-catalyst air-fuel ratio detected by an A/F (air-fuel ratio) sensor. The target air-fuel ratio subsequent to this is gradually changed from the initial value to a specified air-fuel ratio. By this, the initial value of the target air-fuel ratio can be suitably set at a start time of execution of the air-fuel ratio F/B control during the supply of the secondary air. The target air-fuel ratio subsequent to this is gradually changed to a stoichiometric air-fuel ratio, so that a change in engine rotation speed is suppressed and the drivability can be improved.

Inventors: Kita; Masayuki (Kariya, JP), Noma; Toru (Kariya, JP), Fujiki; Kenichi (Toyoake, JP), Takagawa; Tomoyuki (Kariya, JP)

Assignee: Denso Corporation

International Classification: F01N 3/00 (20060101)

Expiration Date: 2019-11-07 0:00:00