Patent ID: 6973777
Filing Date: 2005-12-13
Classification: F01N,Y02T

Abstract:
1. A method for monitoring feeding of secondary air into an exhaust gas of an internal combustion engine, comprising: providing at least two partly separate exhaust systems in each of which are disposed a catalytic converter and, upstream thereof, a lambda probe; delivering secondary air to one of the respective exhaust systems via a secondary air pump and a plurality of individual secondary air lines corresponding to the exhaust systems; and determining a signal a value for a total air mass flow introduced into the exhaust systems from at least one air mass meter, wherein to determine the air mass actually introduced into the individual exhaust systems, the output signals from the lambda probes in the exhaust systems are used to identify an uneven distribution of the air mass fed to each of the exhaust systems, and an uneven distribution is determined by repeatedly forming a ratio of two output signals or the ratio of values derived from the output signals, and, if a predefined number of results falling outside a predefined tolerance band is exceeded, an uneven distribution is deemed to be present.