Abstract: A method of desulfurizing a lean NOx trap (LNT) of an exhaust purification system provided with the LNT and a selective catalytic reduction (SCR) catalyst includes determining whether a desulfurization feasibility condition of the LNT is satisfied, determining whether a desulfurization demand condition of the LNT is satisfied, and performing desulfurization of the LNT if both of the desulfurization feasibility condition of the LNT and the desulfurization demand condition of the LNT are satisfied, wherein the desulfurization of the LNT is performed by repeating a desulfurization lean mode and a desulfurization rich mode according to whether a mode switching condition due to a desulfurization temperature is satisfied and whether a mode switching condition due to generation of H2S is satisfied.

Abstract: Disclosed are a method of correcting a control logic of a selective catalytic reduction (SCR) catalyst and an exhaust system. The control logic may be adapted to calculate an injection amount of a reducing agent for the SCR catalyst at the least. The method may include detecting input variables including temperature of the SCR catalyst and exhaust flow rate, discretizing the input variables, standardizing the discretized input variables, determining whether the discretized input variables are within a correction range, and correcting the control logic of the SCR catalyst if the discretized input variables are within the correction range.

Abstract: Disclosed are a method of determining a correcting logic for a reacting model of an SCR catalyst, a method of correcting parameters of the reacting model of the SCR catalyst and an exhaust system to which the methods are applied. The reacting model of the SCR catalyst is defined by m parameters and has n input variables, where m and n are natural numbers with n smaller than m. The reacting model of the SCR catalyst may be adapted to predict nitrogen oxide (NOx) concentration at a downstream of the SCR catalyst at the least.

Abstract: Disclosed are a method of correcting a control logic of a selective catalytic reduction (SCR) catalyst and an exhaust system. The control logic may be adapted to calculate an injection amount of a reducing agent for the SCR catalyst at the least. The method may include detecting input variables including temperature of the SCR catalyst and exhaust flow rate, discretizing the input variables, standardizing the discretized input variables, determining whether the discretized input variables are within a correction range, and correcting the control logic of the SCR catalyst if the discretized input variables are within the correction range.

Abstract: Disclosed are a method of correcting a control logic of a selective catalytic reduction (SCR) catalyst and an exhaust system. The control logic may be adapted to calculate an injection amount of a reducing agent for the SCR catalyst at the least. The method may include detecting input variables including temperature of the SCR catalyst and exhaust flow rate, discretizing the input variables, standardizing the discretized input variables, determining whether the discretized input variables are within a correction range, and correcting the control logic of the SCR catalyst if the discretized input variables are within the correction range.

Abstract: A method of calculating a nitrogen oxide (NOx) mass reduced from a lean NOx trap (LNT) during regeneration includes calculating a C3H6 mass flow used to reduce the NOx among a C3H6 mass flow flowing into the LNT of an exhaust purification device, calculating a NH3 mass flow used to reduce the NOx among a NH3 mass flow generated in the LNT, calculating a reduced NOx mass flow based on the C3H6 mass flow used to reduce the NOx and the NH3 mass flow used to reduce the NOx, and calculating the reduced NOx mass by integrating the reduced NOx mass flow over a regeneration period.

Abstract: A method of calculating a nitrogen oxide (NOx) mass adsorbed in a lean NOx trap (LNT) of an exhaust purification device includes calculating a NOx mass flow stored in the LNT, calculating a NOx mass flow thermally released from the LNT, calculating a NOx mass flow released from the LNT at the rich air/fuel ratio, calculating a NOx mass flow chemically reacting with the reductant at the LNT, and integrating a value obtained by subtracting the NOx mass flow thermally released from the LNT, the NOx mass flow released from the LNT at the rich air/fuel ratio, and the NOx mass flow chemically reacting with the reductant at the LNT from the NOx mass flow stored in the LNT.

Abstract: A method of calculating an ammonia (NH3) mass generated in a lean NOx trap (LNT) of an exhaust purification device includes sequentially calculating a NH3 mass flow at a downstream of each slice from a first slice to an n-th slice, and integrating the NH3 mass flow at the downstream of the n-th slice over a predetermined time, wherein the calculation of the NH3 mass flow at the downstream of the i-th slice comprises calculating a NH3 mass flow flowing into the i-th slice, calculating a NH3 mass flow generated at the i-th slice, and adding the NH3 mass flow generated at the i-th slice to a value obtained by subtracting the NH3 mass flow used to reduce the NOx and the O2 at the i-th slice from the NH3 mass flow flowing into the i-th slice.

Abstract: A method of regenerating a lean NOx trap (LNT) of an exhaust purification system provided with the LNT and a selective catalytic reduction (SCR) catalyst may include: determining whether a regeneration release condition of the LNT is satisfied; determining whether a regeneration demand condition of the LNT is satisfied; and performing regeneration of the LNT if the regeneration release condition of the LNT and the regeneration demand condition of the LNT are satisfied. In particular, the regeneration release condition of the LNT is satisfied if all of an engine operating condition, an LNT state condition, and a lambda sensor synchronization condition are satisfied.

Abstract: A method of determining suitability of correction for a control logic of a selective catalytic reduction (SCR) catalyst, may include determining a suitability function of the correction based on a previous error and a current error when the correction has been performed, determining a suitability coefficient based on the suitability function of the correction, determining whether the correction may be suitable based on the number of corrections and the suitability coefficient, and resetting the control logic when the correction may be not suitable.

Abstract: A method of regenerating a lean NOx trap (LNT) of an exhaust purification system provided with the LNT and a selective catalytic reduction (SCR) catalyst may include: determining whether a regeneration release condition of the LNT is satisfied; determining whether a regeneration demand condition of the LNT is satisfied; and performing regeneration of the LNT if the regeneration release condition of the LNT and the regeneration demand condition of the LNT are satisfied. In particular, the regeneration demand condition of the LNT is satisfied if a NOx adsorption in the LNT is larger than or equal to a threshold NOx adsorption, and the threshold NOx adsorption is set to a minimum value of a target NOx adsorption in the LNT which changes according to a maximum NOx adsorption in the LNT in cold starting and a NOx purification efficiency of the SCR catalyst.

Abstract: A method of desulfurizing a lean NOx trap (LNT) of an exhaust purification system provided with the LNT and a selective catalytic reduction (SCR) catalyst includes determining whether a desulfurization feasibility condition of the LNT is satisfied, determining whether a desulfurization demand condition of the LNT is satisfied, and performing desulfurization of the LNT if both of the desulfurization feasibility condition of the LNT and the desulfurization demand condition of the LNT are satisfied, wherein the desulfurization of the LNT is performed by repeating a desulfurization lean mode and a desulfurization rich mode according to whether a mode switching condition due to a desulfurization temperature is satisfied and whether a mode switching condition due to generation of H2S is satisfied.

Abstract: A system for purifying an exhaust gas includes an engine, a lean NOx trap (LNT) mounted on the exhaust pipe, a dosing module mounted at the exhaust pipe downstream of the LNT, a selective catalytic reduction (SCR) catalyst mounted at the exhaust pipe downstream of the dosing module, and a controller for performing a denitrification (DeNOx) share between the LNT and the SCR catalyst according to a driving condition of the engine, wherein the controller predicts a NOx purifying ratio of the SCR catalyst according to the driving condition of the engine and adjusts a regeneration efficiency of the LNT based on an actual NOx purifying ratio of the SCR catalyst.

Abstract: A method of regenerating a lean NOx trap (LNT) of an exhaust purification system provided with the LNT and a selective catalytic reduction (SCR) catalyst may include: determining whether a regeneration release condition of the LNT is satisfied; determining whether a regeneration demand condition of the LNT is satisfied; and performing regeneration of the LNT if the regeneration release condition of the LNT and the regeneration demand condition of the LNT are satisfied. In particular, the regeneration release condition of the LNT is satisfied if all of an engine operating condition, an LNT state condition, and a lambda sensor synchronization condition are satisfied.

Abstract: A method of regenerating a lean NOx trap (LNT) of an exhaust purification system provided with the LNT and a selective catalytic reduction (SCR) catalyst may include: determining whether a regeneration release condition of the LNT is satisfied; determining whether a regeneration demand condition of the LNT is satisfied; and performing regeneration of the LNT if the regeneration release condition of the LNT and the regeneration demand condition of the LNT are satisfied. In particular, the regeneration demand condition of the LNT is satisfied if a NOx adsorption in the LNT is larger than or equal to a threshold NOx adsorption, and the threshold NOx adsorption is set to a minimum value of a target NOx adsorption in the LNT which changes according to a maximum NOx adsorption in the LNT in cold starting and a NOx purification efficiency of the SCR catalyst.

Abstract: A method of calculating an ammonia (NH3) mass generated in a lean NOx trap (LNT) of an exhaust purification device includes sequentially calculating a NH3 mass flow at a downstream of each slice from a first slice to an n-th slice, and integrating the NH3 mass flow at the downstream of the n-th slice over a predetermined time, wherein the calculation of the NH3 mass flow at the downstream of the i-th slice comprises calculating a NH3 mass flow flowing into the i-th slice, calculating a NH3 mass flow generated at the i-th slice, and adding the NH3 mass flow generated at the i-th slice to a value obtained by subtracting the NH3 mass flow used to reduce the NOx and the O2 at the i-th slice from the NH3 mass flow flowing into the i-th slice.

Abstract: A system for purifying an exhaust gas includes an engine, a lean NOx trap (LNT) mounted on the exhaust pipe, a dosing module mounted at the exhaust pipe downstream of the LNT, a selective catalytic reduction (SCR) catalyst mounted at the exhaust pipe downstream of the dosing module, and a controller for performing a denitrification (DeNOx) share between the LNT and the SCR catalyst according to a driving condition of the engine, wherein the controller predicts a NOx purifying ratio of the SCR catalyst according to the driving condition of the engine and adjusts a regeneration efficiency of the LNT based on an actual NOx purifying ratio of the SCR catalyst.

Abstract: A method of calculating a nitrogen oxide (NOx) mass reduced from a lean NOx trap (LNT) during regeneration includes calculating a C3H6 mass flow used to reduce the NOx among a C3H6 mass flow flowing into the LNT of an exhaust purification device, calculating a NH3 mass flow used to reduce the NOx among a NH3 mass flow generated in the LNT, calculating a reduced NOx mass flow based on the C3H6 mass flow used to reduce the NOx and the NH3 mass flow used to reduce the NOx, and calculating the reduced NOx mass by integrating the reduced NOx mass flow over a regeneration period.

Abstract: A method of calculating a nitrogen oxide (NOx) mass adsorbed in a lean NOx trap (LNT) of an exhaust purification device includes calculating a NOx mass flow stored in the LNT, calculating a NOx mass flow thermally released from the LNT, calculating a NOx mass flow released from the LNT at the rich air/fuel ratio, calculating a NOx mass flow chemically reacting with the reductant at the LNT, and integrating a value obtained by subtracting the NOx mass flow thermally released from the LNT, the NOx mass flow released from the LNT at the rich air/fuel ratio, and the NOx mass flow chemically reacting with the reductant at the LNT from the NOx mass flow stored in the LNT.

Abstract: Disclosed are a method of determining a correcting logic for a reacting model of an SCR catalyst, a method of correcting parameters of the reacting model of the SCR catalyst and an exhaust system to which the methods are applied. The reacting model of the SCR catalyst is defined by m parameters and has n input variables, where m and n are natural numbers with n smaller than m. The reacting model of the SCR catalyst may be adapted to predict nitrogen oxide (NOx) concentration at a downstream of the SCR catalyst at the least.