| 摘要 |
<p>A valve assembly ( 10 ) comprises a valve stem ( 14 ) with a bore ( 15 ) and radial apertures ( 17 ), and a sleeve ( 18 ) closed atone end and slidable over the valve stem ( 14 ) to obstruct the apertures ( 17 ). At the end of the valve stem opposite the outlet end, the valve stem ( 14 ) defines a fluidic vortex chamber ( 22 ) with both tangential inlets ( 28 ) and non-tangential peripheral inlets ( 26 ), and with an axial outlet ( 24 ) communicating with the bore ( 15 ). The sleeve ( 18 ) defines at least one radial port ( 32 ) near its closed end. The valve assembly operates in a conventional fashion except when approaching closure. Once the last of the apertures ( 17 ) in the valve stem has been closed, the only flow path is through the fluidic vortex chamber ( 22 ). Further movement of the sleeve ( 18 ) alters the distribution of the flow between the non-tangential inlets ( 26 ) and the tangential inlets ( 28 ), so adjusting the strength of the fluidic vortex and the resistance to fluid flow. The valve assembly ( 10 ) suppresses erosive and cavitational wear of the valve mechanism, and can provide a wide range of flow modulation.</p> |
