| 摘要 |
<p>A downhole actuator typically for a downhole tool such as a valve, and typically for incorporation in a string of tubulars in an oil or gas well has a central axis with radially movable counterweights on opposite sides of the axis, which move radially outward to change the activation state of the actuator. The counterweights are supported by link arms which control the movement of the counterweights in response to centrifugal force created by rotation of the body, for example, during rotary drilling operations of the string. Radial outward movement of the counterweights typically transmits axial forces between sleeves at the upper and lower ends of the counterweights, so when the counterweights move radially outward, the upper and lower sleeves approach one another, which typically triggers the actuator.</p> |
