Patent ID: 8122976

Claim:
A selectively operable downhole valve positioned within a core sampling apparatus, the core sampling apparatus having an inner barrel, the valve comprising: a throughbore through which the inner barrel of the core sampling apparatus may pass; an obstructing member for selectively obturating the throughbore; a sensing mechanism comprising a cammed surface partially protruding into the throughbore of the downhole valve; and an actuation mechanism comprising a lever having a first pivot axis, the lever connecting the sensing mechanism to the obstructing member; whereby the actuation mechanism is configured such that movement of the inner barrel of the core sampling apparatus through the throughbore moves the cammed surface radially with respect to the throughbore, thereby moving the lever around the first pivot axis and initiating movement of the obstructing member, the lever being pivotally connected to the obstructing member at a second pivot axis which is moveable relative to the obstructing member being arranged as the obstructing member moves to open or close the throughbore.