Patent ID: 6830043
Filing Date: 2004-12-14
Classification: F01N,Y02T

Abstract:
A secondary air supply abnormality detection system for an engine system including an internal combustion engine, a catalyst disposed in an exhaust passage of the engine for cleaning exhaust gas, and a secondary air supply system for supplying secondary air into the exhaust passage upstream of the catalyst, the secondary air supply abnormality detection system comprising:air-fuel ratio sensing means disposed in the exhaust passage upstream of the catalyst and downstream of a secondary air supply opening for sensing an air-fuel ratio of the exhaust gas; air-fuel ratio estimating means for estimating an air-fuel ratio of air-fuel mixture supplied to the engine; secondary air flow rate calculating means for calculating a flow rate of the secondary air supplied from the secondary air supply system based on the air-fuel ratio of the air-fuel mixture supplied to the engine, which is estimated by the air-fuel ratio estimating means, and the air-fuel ratio, which is sensed by the air-fuel ratio sensing means when the secondary air is supplied from the secondary air supply system; and abnormality determining means for determining an abnormality in the engine system including the secondary air supply system based on the secondary air flow rate calculated by the secondary air flow rate calculating means.