When closing, the sphere surface is getting gradually to the seat so that efficiently remove the obstacle of scaring and scaling, and reach reliable sealing by the self-lock effect of angle eccentric.

• 关闭时蝶板球面逐渐接近阀座；可有效地切除结疤；结垢等现象；依靠角偏心的自锁作用；开关省力实现可靠密封.