Patent ID: 6991210

Claim:
An actuator for driving a valve, comprising: a piston rod fixed with pistons at both left and right ends of the rod; left and right side cylinders supporting each of said pistons for the pistons to slide freely towards the center of said piston rod; a first passageway for communicating a left side cylinder room of the left side cylinder with a left side cylinder room of the right side cylinder where both cylinders are separated by said pistons; a second passageway for communicating a right side cylinder room of the left side cylinder with a right side cylinder room of the right side cylinder where both cylinders are separated by said pistons; and a converter for converting a reciprocating motion of said piston rod towards the center of said rod into a rotating motion of a valve driving shaft, wherein said first and second passageways are in or around connecting members of said left and right side cylinders.