| 摘要 |
A subsea electric actuator comprises an electric motor and a telescopic drive connection (8) from the motor to a drive unit (10, 11, 12) which can be moved to and fro and converts rotary motion of the connection to linear motion of an actuating stem (5). A return spring (14) is operable on the drive unit to urge the actuating stem towards a datum state. An electromagnetic latch (15) is operative when set to maintain the drive unit in a predetermined position so as to decouple the action of the return spring whereby the stem can be advanced and retracted relative to the drive unit free from the action of the return spring. De-energisation of the latch allows the return spring to operate on the drive unit to return the actuating stem to the datum state. Various forms of electromagnetic latch are described. |
