Method of improving accuracy of purge fuel amount and active purge system therefor

An active purge system, comprising:

• a purge control solenoid valve (PCSV) configured to open and close a gas discharge line which connects a canister collecting a fuel evaporative gas of a fuel tank to an intake manifold;
• and
• a purge controller configured to:
• perform, when purge is executed in which the PCSV is opened, purge control using a purge fuel amount in which a basic purge fuel amount of a purge flow rate model using a primary weighting factor of a concentration value weighting factor by applying an ambient air temperature detected by a temperature sensor provided in a vehicle to a concentration model value of the gas concentration model and a secondary weighting factor of a purge learning value to which an air-fuel ratio change due to purge is applied, and
• perform purge learning according to a variable air-fuel ratio in an air-fuel ratio control value change condition which is identified using one or more of a PCSV duty, an engine warm-up, and a target air-fuel ratio.

A method of controlling a purge fuel amount of an active purge system (APS), the method comprising:

• calculating a basic purge fuel amount using a purge flow rate model;
• calculating a concentration value weighting factor in which a change in a concentration model value of a gas concentration model is compensated for as the primary weighting factor with respect to a purge learning value and an ambient air temperature reflected coefficient;
• calculating a secondary weighting factor with respect to the purge learning value according to the air-fuel ratio change due to purge;
• setting the primary weighting factor and the secondary weighting factor of the concentration value weighting factor as a purge fuel amount control coefficient;
• and
• compensating for the basic purge fuel amount using the purge fuel amount control coefficient.