Diesel Particulate Trap Protection Against Uncontrolled Regeneration via Selective Flow Modulation

Possible techniques to protect the filter against a failure scenario, so far reported, include filter by-passing and limiting the engine A/F ratio. Both techniques aim at controlling the oxygen content of the exhaust gas and thus reducing the oxidation rate in the filter. In this paper a new method for the protection of the trap is presented. This method, called Selective Flow Modulation (SFM) aims at controlling the reaction rate via the modulation of the exhaust gas flow through the filter. For the practical application of such a method, it is necessary to split the filter into at least two parts and to use at least one device for the flow modulation. In addition, a number of different possible SFM configurations are presented and their characteristics are analysed together with the experimental results of the technique applied on two engines, one heavy and one light duty.