Measuring ageing state of catalyser in IC engine exhaust system - measuring upstream and downstream lambda values with engine operated with rich then weak mixt. or vice=versa and then allowed to idle

摘要

The engine is first operated with a non-unity lambda value until the catalyser is completely filled with oxygen or emptied. The engine is then operated with a lambda value varied from unity in the opposite sense so that the upstream lambda value changes in the corresp. direction. The time from the starting point and the actual time are measured at which the downstream lambda value changes in the same sense and exceeds a threshold. The engine is allowed to idle and the ageing state parameter AZ formed as a constant k times the time interval delta-t divided by the integral ILM : AZ = k X (delta-t/ILM). ADVANTAGE - Enables very accurate measurement results to be achieved with absolute inaccuracies having hardly any effect.