| 摘要 |
An electrically operated valve actuator effective for shifting a valve (10) between open and closed positions is disclosed, the valve actuator comprising a movable member in the form of a valve stem (21) connected to a valve body (14), the movable member being driven by an electric motor (22) in linear motion between valve closing and valve opening positions, wherein electrical power to the motor is supplied via a current (25) control including a supplied current detection device. The movable member is designed for an idling length of travel (L) in the opening and closing directions during which the valve (10) is either fully open or fully closed, and the movable member is associated with buffer means (30) that during the idling length of travel gradually increases the torque and power required to move the movable member further in the open and closed positions of the valve (10), respectively. |
