| 摘要 |
<p>An expansible chamber (52) is expanded to create a partial vacuum within the chamber. Following expansion, a burst of fluid pressure, attended by fluid flow and an acoustical wave, is introduced into the chamber. Simultaneously, the chamber is forcibly contracted. This transducer produces a square acoustical wave. When the transducer is incorporated into the hutch of a mining jig (2), it results in the pulling of agglomerations of minute particles down out of the gangue and into the hutch chamber. An annular valve member (42) is movable axially towards and away from a valve seat (24). The valve member includes a concave sealing surface (44) which mates against a convex valve seat (24) having a smaller radius of curvature (R,r). Sealing contact is made adjacent the high pressure side of the valve. A gap (48) is created which widens from the zone of contact towards the low pressure side of the valve. When the valve is opened a small amount, a gap is created between the sealing surface and the valve seat which narrows from the high pressure zone to the low pressure zone.</p> |
