Test Method Development and Understanding of Filter Ring-off-Cracks in a Catalyzed Silicon Carbide (SiC) Diesel Particulate Filter System Design

As the use of diesel engines increases in the transportation industry and emission regulations tighten, the implementation of diesel particulate filter systems has expanded. There are many challenges associated with the design and development of these systems. Some of the key robustness parameters include regeneration, efficiency, fuel penalty, engine performance, and durability.

One component of durability in a diesel particulate filter (DPF) system is the filter's ability to resist ring-off-cracking (ROC). ROC is described as a crack caused primarily by thermal gradients, differentials, and the resulting stresses within the DPF that exceed its internal strength. These cracks usually run perpendicular to the substrate flow axis and typically result in the breaking of the substrate into separate halves. Unlike an oxidation catalyst converter where conversion efficiency is mainly dependent on surface area, a ROC in a filter can have a very detrimental effect on filtration efficiency performance.

This paper will focus on a test methodology associated with consistently producing the ROC phenomenon. Also summarized will be the following related sub-topics:

1. (1)
   The effects of soot loading and resulting temperature distributions within the DPF.
2. (2)
   The use of filtration efficiency as an indicator of filter ROC occurrence.
3. (3)
   Thermal stress modeling of ROC occurrence conditions.