Patent ID: 6883307
Filing Date: 2005-04-26
Classification: F01N,F02D,Y02T

Abstract:
1. An internal combustion engine diagnosis apparatus comprising a cleanup catalyst arranged in an exhaust pipe of an internal combustion engine; and an HC adsorption catalyst arranged in parallel to and downstream of said cleanup catalyst, during high temperature period said HC adsorption catalyst desorbing and cleaning up HC desorbed during low temperature period, wherein degradation of said HC adsorption catalyst is diagnosed based on temperature of said HC adsorption catalyst while HC is being desorbed from said HC adsorption catalyst (during HC desorbing period) and wherein a temperature gradient during evaporating of water adsorbed to said HC adsorption catalyst is calculated, and said temperature gradient is compared with a preset diagnosis threshold, and if said temperature gradient is smaller than said diagnosis threshold, it is judged that said HC adsorption catalyst is degraded.