Patent ID: 7343737
Filing Date: 2008-03-18
Classification: F02D

Abstract:
1. A system for purging sulfate from a NOx trap associated with oxidation catalyst-forming means, and integrated in an exhaust line of a motor vehicle diesel engine, in which the engine is associated with common manifold or “rail” fuel feeder means for feeding fuel to the cylinders of the engine and adapted, by modifying engine operation control parameters, to cause the engine to switch between operating with a lean mixture and with a rich mixture, wherein the fuel feeder means are adapted to define four strategies for controlling the operation of the engine with a lean mixture for the purpose of obtaining different temperature levels in the exhaust line, the first strategy being referred to as a normal strategy and corresponding to normal operation of the engine, the second strategy being referred to as a level 1 strategy, the third strategy being referred to as a level 2 strategy, and the fourth strategy being referred to a super-calibrated level 2 strategy, the temperature level obtained by applying the fourth, super-calibrated level 2 strategy being higher than that obtained by applying the third, level 2 strategy, the temperature level obtained by applying the third, level 2 strategy being higher than that obtained by applying the second, level 1 strategy, which is itself higher than that obtained by applying the first, normal strategy, and wherein the fuel feeder means are connected to: means for detecting a request to purge sulfate so as to control the feeder means in order to engage operation of the engine in the second, level means for monitoring the activation state of the catalyst-forming means to engage the fourth, super-calibrated level means for acquiring the temperature level in the exhaust line to engage operation of the engine with a rich mixture when this temperature level exceeds a predetermined target temperature during a predetermined first time period or for switching off sulfate purging if this temperature is not reached before a predetermined maximum second time period expires; and means for monitoring the rich mixture operation of the engine: