| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust gas purification system and its control method capable of correctly displaying a residual amount display and warning the residual amount by detecting a residual amount of urea water with high accuracy by adjusting responsiveness of a filtering to an output signal of a tank level sensor according to a residual amount of urea water in a urea water tank loaded in a vehicle.SOLUTION: An exhaust gas purification system including a urea water tank 20 loaded on a vehicle, and a tank level sensor 24 detecting a liquid surface level WL of urea water W in the urea water tank 20, further includes a data processing device 10a for processing an output signal Ss of the tank level sensor 24 by a low-pass filter F, calculating a residual amount Vw of the urea water W on the basis of an output signal Sf processed by the low-pass filter F, and changing a time constant Tf of the low-pass filter F according to the residual amount Vw of the urea water W in the urea water tank 20. |
