Safety cap device for controlling pressure in radiator and method for controlling pressure using the same

A safety cap device for controlling a pressure in a radiator of a cooling system for a vehicle, the device comprising:

• a valve seat having a valve receiving space therein and a first communicating hole formed in the valve receiving space;
• a negative pressure valve provided movably in a vertical direction inside the first communicating hole;
• a seal disposed on a receiving surface of the valve seat in the valve receiving space and disposed movably with the negative pressure valve, the seal having a second communicating hole which is formed at a central portion of the seal and communicates with the first communicating hole;
• a positive pressure valve disposed on the seal and having a third communicating hole which is formed at a central portion of the positive pressure valve and communicates with the second communication hole;
• a cap covering an upper portion of the valve seat;
• a spring interposed between the positive pressure valve and the cap;
• and
• a fluid receiving part provided in the valve seat to prevent cavitation from being generated when an internal fluid expands,
• wherein the fluid receiving part includes a receiving space for receiving the internal fluid and moving together with the negative pressure valve, and
• wherein the fluid receiving part includes a foam part collecting air bubbles, and the foam part is disposed in the receiving space of the fluid receiving part.