Why can Korean anti-overflow pot cover prevent overflow?

The structure is that the top of the pot cover is provided with an anti-overflow hole, and the anti-overflow hole is covered with an anti-overflow small cover; A fixed bracket with a hole is connected with the pot cover main body in the overflow prevention hole; One end of the combined spring is connected to the spill-proof small cover, and the other end is connected to the fixed bracket. The patented product of the utility model can automatically prevent boiling liquid from overflowing, which is a very practical new pot cover.