Ball valve locking mechanism controlled by medium pressure

The invention discloses a ball valve locking mechanism controlled by medium pressure, and belongs to the technical field of valves. The mechanism comprises a cylinder block; the cylinder block is provided with a middle through hole and an annular piston cavity surrounding the middle through hole; a transmission rod penetrates through the middle through hole; one end of the transmission rod is in transmission connection with a valve rod of a ball valve, and the other end of the transmission rod is connected with a hand wheel rod; a piston ring is assembled in the annular piston cavity of the cylinder block, and divides the annular piston cavity into an elastic pressing cavity far from the hand wheel rod and a punching cavity near the hand wheel rod; a spring is assembled in the elastic pressing cavity; an annular disc plate is arranged at the outer peripheral part of the hand wheel rod; a locking pin is tightly inserted in the cylinder block; one end of the locking pin is fixed on the piston ring, and the othe