| 摘要 |
A valve on an inner string can only be closed with multiple movements in opposed directions that occur after a predetermined force is held for a finite time. Holding the force against resistance eventually allows movement that arms the valve. A set down and pickup force will then close the valve. The surrounding string has a constriction that interacts with a j-slot to rotate a wedge with a first peak into alignment with a peak on a second wedge that can only translate against a spring bias. The second wedge is eccentrically linked to a ball that rotates between and open and a closed position.
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