Patent ID: 8348233

Claim:
A butterfly valve, comprising: a valve body; a seat ring mounted on a flow passage of the valve body; a disc rotatably mounted to the valve body, and configured to open and close the flow passage by being attached to the seat ring; a driving device configured to linearly move and rotate the disc so as to prevent interference between the disc and the seat ring when the flow passage of the valve body is open and closed; and a shaft mounted to the valve body so as to perform a linear motion and a rotational motion, and configured to connect the disc and the driving device to each other, wherein the driving device comprises: a driving unit configured to linearly move or rotate the shaft with respect to the valve body; and a motion converting unit configured to move the disc in a direction to be close to or distant from the seat ring as the shaft is linearly moved, and wherein the driving unit comprises: a driving shaft rotatably mounted to a housing, and having a manipulation wheel; a slide nut slidably-moving on the driving shaft as the driving shaft is rotated; a first driving unit configured to linearly move the shaft as the slide nut is slidably moved; and a second driving unit configured to rotate the shaft as the slide nut is slidably moved.