Evaporation leakage checking system and checking method of evaporation leakage using the same

A checking method of an evaporation leakage for an evaporation leakage checking system including a pump including an inlet and an outlet;

• a pump passage unit having a first end that is connected with the inlet or the outlet, and a second end;
• a tank passage unit having a first end that is connected with a fuel tank storing a fuel, and a second end;
• a specified passage unit having a first end that is connected with the second end of the pump passage unit, and a second end that is connected with the second end of the tank passage unit;
• an atmosphere passage unit having a first end that is connected with the second end of the tank passage unit or the second end of the specified passage unit, and a second end that is exposed to the atmosphere;
• a flow-passage area changing unit changing a flow-passage area of the specified passage unit to a plurality of areas including a first area and an Nth area, N being a value greater than one;
• an atmosphere valve unit changing a flow-passage area of the atmosphere passage unit;
• a pressure sensing unit sensing a pressure in the pump passage unit;
• and a control unit controlling operations of the pump, the flow-passage area changing unit, and the atmosphere valve unit, the checking method comprising:
• starting a sensing of the pressure by using the pressure sensor;
• starting an operation of the pump;
• storing a pressure relative to the pressure sensed by the pressure sensor in a case where the flow-passage area of the specified passage unit is the first area as a first pressure;
• changing the flow-passage area of the specified passage unit to the Nth area by using the flow-passage area changing unit;
• storing a pressure relative to the pressure sensed by the pressure sensor in a case where the flow-passage area of the specified passage unit is the second area as an Nth pressure;
• calculating a leakage threshold that is a threshold used to check an existence of an evaporation leakage that is a leakage of an evaporation that is an evaporated fuel, based on the first pressure, the first area, the Nth pressure, the Nth area, and a reference area that is predetermined;
• closing the atmosphere passage unit by changing the flow-passage area of the atmosphere passage unit by using the atmosphere valve unit;
• checking the existence of the evaporation leakage, based on the leakage threshold and a checking pressure that is the pressure sensed by the pressure sensor in a case where a communication between the tank passage unit and the pump passage unit is allowed.