| 摘要 |
<p>A closure mechanism (20) for preventing fluid access to an inner tube (26) of a core barrel assembly (24) is disclosed in which the closure mechanism (20) is configured to move from an open, or unoccluded, condition to an occluded condition in response to increased fluid flow rates and pressure differentials occurring at the closure mechanism (20). The closure mechanism is also configured to maintain occlusion of the inner tube (26) under substantially all types of drilling conditions, and particularly those where conventional closure mechanisms may fail, such as in horizontal drilling. The closure mechanism (20) generally includes a conduit structure associated with the inner tube (26), and having a seat (36), an occlusion means (42), such as a ball (52), and releasing structure (40) which maintains the occlusion means (42) in spaced relationship to the seat (36) until increasing pressure differentials result in release of the occlusion means (42) to register with the seat (36). <IMAGE></p> |
