Bidirectional and eccentric semispherical valve with automatic alignment and sealing

The invention discloses a bidirectional and eccentric semispherical valve with automatic alignment and sealing, and aims to overcome a problem that the axial position of a valve rod of an existing bidirectional and eccentric semispherical valve in the working process results in an inability of realizing closure with zero leakage when a semispherical side of a hemispheroid and a sealing side of a valve seat are unable to contact with each other completely because of an error existing between the semispherical side and the sealing side. The semispherical valve comprises a valve body, the valve seat, the eccentric valve rod mounted inside the valve body, and the hemispheroid fixed on the valve rod, wherein the valve rod is mounted inside an upper sliding sleeve and a lower sliding sleeve of the valve body in a supporting manner with a capability of fluctuating up and down, and a cavity of the valve body is provided with the space resulting in eth up-and-down fluctuation of the hemispheroid. When the error exists