| 摘要 |
<p>A proportional, pilot-operated directional valve has a sleeve with at least four sets of radial holes, and a spool disposed within the sleeve, with a channel being defined between the spool and the sleeve. The spool has at least two sets of radial holes, and the exterior surface of the spool has annular protrusions, each being in at least partial contact with the inner wall of the sleeve. When the valve is in an open position, the first set of radial holes of the sleeve is in communication with one of the two sets of radial holes of the spool, the second and third sets of radial holes of the sleeve are each at least in partial communication with the channel, and the fourth set of radial holes of the sleeve is in communication with the other of the two sets of radial holes of the spool. The spool may be kept in an open position by pressure from a flow of fluid that is provided at one end of the sleeve. <IMAGE></p> |
