Control method for dual path NOx adsorber system

A method of controlling regeneration of NOx adsorbers in a dual path NOx adsorber system that treats exhaust during operation of an internal combustion engine, comprising the steps of:

• directing substantially equal amounts of the total exhaust into each path of the adsorber system, such that each adsorber is in adsorption mode simultaneously, with each path receiving a substantially half proportion of the exhaust;
• determining when the adsorber on a first path is to be regenerated;
• in response to the determining step, limiting the flow of exhaust to approximately 5% or less to the first path and directing the remaining flow to the second path, such that the first path receives a low proportion of the exhaust and the second path receives a high proportion of the exhaust;
• regenerating the adsorber in the first path, such that the dual path NOX adsorber system is in a first path regeneration mode;
• limiting the flow of exhaust to approximately 5% or less to the second path and directing the remaining flow to the first path, such that the second path receives a low proportion of the exhaust and the first path receives a high proportion of the exhaust;
• regenerating the adsorber in the second path, such that the dual path NOx adsorber system is on a second path regeneration mode;
• and
• repeating the above steps, such that both adsorbers are in adsorption mode substantially longer than in regeneration mode, and such that during operation of the engine, each path receives three periodically repeating exhaust flow conditions, each exhaust flow condition having a different proportion of the total exhaust as follows:
• a substantially half proportion during adsorption on that path, a low proportion during regeneration on that path, and a high proportion during adsorption on that path.