| 摘要 |
<p>A ball valve including a valve housing, a valve seat retainer fitted in a fluid passageway of the valve housing and being movable forwardly and backwardly within a given distance along the direction of movement of pressurized fluid, a sealed chamber formed in a portion of a spacing defined by the rear wall of the valve seat retainer and the inner wall of the valve housing, a channel formed in the valve housing for communicating the sealed chamber and an upstream fluid passageway, and a switch valve for opening or closing the channel to allow or prohibit movement of fluid within the upstream fluid passageway toward the sealed chamber, to vary the pressure force of the pressurized fluid acting on the valve seat retainer in the direction of movement of the pressurized fluid, whereby the valve seat retainer and the valve seat are displaced in the direction of movement of the fluid so as to come into contact with the periphery of the ball-shaped valve member when the pressurized fluid enters into the sealed chamber, and shifted in the direction opposite to the fluid movement to be thus disengaged therefrom when the pressurized fluid from the channel is precluded from entering the sealed chamber.</p> |
