| 摘要 |
<p>A high-pressure primary fluid control valve (10) and a multi-pressure selector fluid control valve (210) are disclosed for operating a fluid-actuated device. Preferably a spherical ball-poppet (42,52,242,252) and frusto-conical valve seat (36,46,240,250) adapted for substantially line-contact therebetween are provided with an upstream flow area adjacent the line-contact in order to substantially minimize sonic flow damage to the actual sealing surface of the valve seat by shifting it away from such line-contact seating. Preferably, the ball-poppet is movable within a poppet guide (62,72,262,272) that is allowed to float radially in order to allow the ball-poppet to be substantially self-centering with respect to the valve seat. In addition, cross-over leakage is preferably negated by closing an exhaust ball-poppet just prior to opening a supply ball-poppet. These principles and features are equally applicable to either or both of the primary or the multi-pressure selector fluid control valves. <IMAGE></p> |
