Catalytic Converter Hot Vibration Test Methods at The 3M Company

摘要

While emission standards require greatly reduced levels of certain vehicle emissions, additional regulations require those levels to be met for the useful life of the vehicle, currently specified as 10 years/100,000 miles for light duty vehicles. As vehicle manufacturers anticipate requirements of 15 years/150,000 miles, converter performance and durability must be predicted further into the future. The realities of the world market and competitive pressures require greatly improved test methods to establish converter robustness well in advance of the start of production. Such methods must enable robustness assessment in a compressed timeframe and at low cost. Often, a converter concept must be evaluated well before the first prototype engine or vehicle is assembled. To address these needs, a new approach to converter package durability was conceived by an industry group whose members shared the goal of early converter life prediction. Members of that group have taken somewhat different paths in the implementation of that concept. This paper describes the approach and test procedures utilized at The 3M Company. Initially the focus was placed on duplicating vehicle conditions. While producing excellent test results, the goal of evaluating package durability quickly and at low cost was not met. Further evaluation of internal and customer needs revealed that the required information could be generated much more quickly and much less expensively. This paper compares and contrasts previous and current test procedures in terms of goals, expense, time, mat stress objectives, thermal exposure, and vibration exposure. Two procedures are described: one for substrate support screening and a second for complete converter testing under quasi-real world conditions. Both procedures yield relative robustness levels among mat mount designs.