| 摘要 |
<p>An electrically operated hydraulic valve comprises a valve assembly that provides a common valve passageway 5, an inlet port 20, an outlet port 22 and a return port 23 connected to the passageway 5 and an axially movable valve member 8 which allows in a first position fluid flow between the outlet port 22 and the return port 23 while closing the inlet 20, and in a second position, axially displaced from the first position, fluid flow between the inlet port 20 and the outlet port 22 while closing the return port 23. A spring 13 provides a restoring force urging the valve member to its first position. An electrically operated actuator 19 coupled to the valve member comprises a permanent magnet 24 and a cooperating electrical coil 25 having an associated magnetic core 27, one or other of the magnet 24 and the coil 25 constituting a stator and the other constituting an armature which is coupled to the valve member to move it from the first position to the second position. The actuator is disposed for operation by an electrical supply which provides a unidirectional current pulse to the coil.</p> |
