Positive Indication of Latching in an Inner and Outer Tube Assembly, Especially for Downhole Assemblies

Abstract

A latch body ( 10 ) incorporates spring-loaded latches ( 11 ) and ( 12 ) which secure the inner tube assembly in place by latching against a shoulder in an adaptor coupling. At the lower end of the latch body ( 10 ) there are water inlet ports ( 13 ), a landing shoulder ( 14 ) and water outlet ports ( 15 ). The valve mechanism ( 20 ) includes a piston ( 21 ) slidable within upper cylinder ( 22 ) above the inlet ports ( 12 ) which has a recess ( 23 ) at its upper end for receiving a ball ( 24 ) and a sealing flange ( 25 ), at its lower end. The upper cylinder ( 22 ) has a recess ( 26 ) in which part of the ball can seat to cock the piston. A second cylinder ( 27 ) between the inlet ports ( 13 ) and outlet ports ( 15 ) carries a spring guide ( 28 ) having a valve seat ( 30 ) at its upper end. A spring ( 31 ) acts against the sealing flange ( 25 ). When the piston ( 21 ) is cocked, the sealing flange ( 25 ) is adjacent to and spaced from the valve seat ( 30 ) and is forced spaced from the valve seat ( 30 ) and is forced against the valve seat ( 30 ) by water pressure to close the valve and uncock the piston.

1 . A latch body and valve mechanism for providing a positive indication of the correct latching of an inner tube assembly having a water inlet port above a latching shoulder and a water outlet port below the latching shoulder, and wherein the valve mechanism comprises a piston moveable within a first cylinder above the inlet port between an uncocked position and a cocked position in which a cocking mechanism restricts movement of one end of the piston into the first cylinder, the piston having a sealing flange at its other end, a second cylinder between the inlet port and outlet port having a spring guide therein, the spring guide having a valve seat facing the sealing flange and an opening at its other end leading to the outlet port, a spring within the spring guide adapted to bear against the flange of the piston, the arrangement being such that when the piston is in the cocked position the flange is within the top of the second cylinder adjacent to but spaced from the valve seat and prevented from moving away from the valve seat by the cocking mechanism, the flange being forced against the valve seat by water pressure to close the valve and uncock the piston. 
   
   
       2 . A latch body and valve mechanism according to  claim 1  wherein the cocking mechanism comprises a ball adapted to seat in a recess at the top of the piston away from the flange and the first cylinder has a recess for receiving part of the ball, the arrangement being such that the piston is cocked by withdrawing it from the cylinder so that the ball may sit partly in the recess and bear against the end of the piston to prevent the piston from retracting into the cylinder. 
   
   
       3 . A latch body and valve mechanism according to  claim 2  wherein the closure of the valve enables the ball to move from the recess in the first cylinder to the recess in the piston so that upon release of the water pressure the piston will be forced by the spring into the first cylinder with the sealing flange of the piston moving away from the valve seat to open the valve. 
   
   
       4 . A latch body and valve mechanism according to  claim 1  further including a sleeve portion above the valve mechanism having a pair of opposed slots through which latches project to engage an adaptor coupling. 
   
   
       5 . A latch body and valve mechanism according to  claim 4  wherein each latch has an upper shoulder adapted to engage the adaptor coupling and lower sloping shoulders adapted to be engaged by the lower end of the slot so to retract the latch when the sleeve portion is raised. 
   
   
       6 . A latch body and valve mechanism according to  claim 2  wherein the piston is cocked by laying the latch body and valve mechanism horizontal, inserting a rotatable tool into the inlet port to engage the upper surface of the sealing flange of the piston, and rotating the tool so that the piston is moved against the action of the spring to allow the ball to partly enter the recess in the first cylinder.