LNT OPERATION METHOD FOR PREVENTING OVERHEAT DUE TO THE SOx DESORPTION

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The present invention relates to an LNT operation method for preventing degradation due to desorption of SOx, which comprises : an uptake determination step (S100) determining whether the uptake of NOx (nitrogen oxides) and SOx (sulfur oxides) collected by an LNT (Lean NOx Trap) is greater than a reference value; a diesel particulate filter (DPF) regeneration step (S200) of repetitively getting a fuel injection amount to be in a rich state and in a lean state for combusting particulate matter (PM) collected at a DPF in the case that the uptake is greater than the reference value; an LNT heating step of maintaining the fuel injection amount to be in the rich state until exhaust gas arrives at poisoning temperature for desorption of the SOx collected at the LNT; an operation state determination step of determining whether a vehicle operation state is under a specific operation condition while the fuel injection amount is maintained to be in the rich state; and an SOx poisoning step of maintaining the fuel injection amount to be in the rich state and desorbing the SOx collected at the LNT in the case that the vehicle operation state is not under the specific operation condition. The present invention raises the internal temperature of the LNT to a limit or higher in the specific operation state during the desorption of the SOx to prevent the degradation of the LNT, and as the degradation of the LNT is prevented, performance is improved as compared with conventional LNT regeneration performance.(AA) Vehicle is traveling(S100) Determine whether the uptake of NOx and SOx collected by an LNT is greater than a reference value(S200) Repetitively get a fuel injection amount to be in a rich state and in a lean state for combusting PM collected at a DPF(S300) Maintain the fuel injection amount to be in the rich state until exhaust gas arrives at poisoning temperature(S400) Determine whether a vehicle operation state is under a specific operation condition while the fuel injection amount is maintained to be in the rich state(S500) Desorb the SOx collected at the LNTCOPYRIGHT KIPO 2016