Axial-load-actuated rotary latch release mechanisms for casing running tools

Abstract

A rotary latch release mechanism includes axially-aligned upper and lower rotary latch components carried on and rotationally coupled to upper and lower latch assemblies, respectively. The latch release mechanism is movable from an axially-latched position to an axially-unlatched position in response to relative rotation between the upper and lower rotary latch components. The latch release mechanism has a movable land surface that acts in response to relative axial displacement to induce the relative rotation required to release the latch. The latch release mechanism may be configured such that the axial movement of the movable land surface will cause the relative axial movement required to release the latch in combination with the required rotation. Accordingly, the rotary latch mechanism operates in response to externally-controlled axial movement of a movable land surface carried by the latch release mechanism, without requiring externally-induced rotation.

What is claimed is: 
     
         1 . A latch release mechanism acting between:
 (a) a generally cylindrical main body having a main body bore; and   (b) a generally cylindrical load adaptor coaxially disposed within the main body bore and both axially and rotatably movable therein, with a lower end of the load adaptor being operatively engageable with an axial-load-actuated latching linkage disposed within the main body;   
       wherein the latch release mechanism comprises:
 (c) a generally cylindrical load adaptor extension coaxially mounted to an upper region of the load adaptor and having a lower portion forming a skirt defining a first annular space between the load adaptor extension and an outer cylindrical surface of the load adaptor; 
 (d) a primary trigger element having a primary trigger bore, wherein:
 an upper portion of the primary trigger element is coaxially disposed within said first annular space, and is mounted to and carried by the skirt so as to be axially and rotationally movable relative to the skirt within defined constraints; 
 a lower portion of the primary trigger element extends over an upper region of the main body and is axially movable relative thereto; and 
 the primary trigger element carries a downward-facing primary trigger reaction surface; 
 
 (e) a secondary trigger element coaxially disposed within a secondary annular space defined by the skirt and the primary trigger, wherein:
 the secondary trigger element is mounted to and carried by the skirt so as to be axially movable, within defined constraints, relative to the skirt, but non-rotatable relative to the skirt; and 
 the secondary trigger element is coupled to the primary trigger element so as to be axially and rotationally movable relative to the primary trigger element within defined constraints; 
 
 (f) a secondary trigger extension having a secondary trigger extension bore and being coaxially mounted to a lower end of the secondary trigger element; 
 (g) a main body extension coaxially and fixedly mounted to an outer cylindrical surface of the main body, said main body extension having a cylindrical upper portion coaxially disposed within the secondary trigger extension bore, wherein:
 the inner and outer diameters of the cylindrical upper portion of the main body extension substantially correspond to the inner and outer diameters of the primary trigger element; 
 the cylindrical upper portion of the main body extension defines an upward-facing first reaction surface configured for mating engagement with the primary trigger reaction surface; 
 an external shoulder defining a second reaction surface is provided on a lower region of the main body extension; 
 the main body extension is axially movable relative to, and is co-rotatable with, the secondary trigger extension; and 
 the lower end of the secondary trigger extension is configured to be engageable with the second reaction surface; 
 
 
       wherein the primary and secondary trigger elements are configured such that axial compressive load applied to the load adaptor will be reacted by contact and engagement of the first reaction surface with the primary trigger reaction surface and by contact and engagement of the second reaction surface with the lower end of the secondary trigger extension, causing corresponding axial displacement between the load adaptor and the main body, thereby inducing rotation and axial movement of the secondary trigger element relative to the primary trigger element, thus generating torque and corresponding rotation to unlatch the latching linkage. 
     
     
         2 . A latch release mechanism as in  claim 1  wherein a plurality of primary trigger dog teeth, each comprising a primary trigger dog tooth load flank, a primary trigger dog tooth crest, and a primary trigger dog tooth lock flank, are provided on the primary trigger reaction surface, with a corresponding plurality of mating reaction dog pockets, each defining a reaction pocket load flank, a reaction pocket crest, and a reaction pocket lock flank, being provided on the first reaction surface.