Latch release mechanism

Abstract

A rotary latch release mechanism includes axially aligned upper and lower rotary latch members that are carried on and rotatably 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 members. The latch release mechanism has a movable platform surface that acts in response to the relative axial displacement to cause the relative rotation required to release the latch. The latch release mechanism may be configured such that axial movement of the movable platform surface will cause relative axial movement and rotation required for releasing the latch. Thus, the rotary latch mechanism operates in response to externally controlled axial movement of the movable platform surface carried by the latch release mechanism without the need for externally induced rotation.

Description

Technical Field

[0001] The present disclosure generally relates to devices and mechanisms for releasably latching two coaxially positioned and mating rotating components such that relative axial displacement of the rotating components is prevented when in a latched position, but axial displacement is permitted when the rotating components are in an unlocked position. Background Art

[0002] Power tongs have been used for many years to "make up" (i.e., assemble) threaded connections between segments (or "joints") of tubing, and to "break out" (i.e., disassemble) threaded connections in coordination with the drilling rig's lifting system as the tubing string is run into or out of a petroleum well. A tubing string typically includes a plurality of tubing sections having externally threaded ends, connected end-to-end by an internally threaded cylindrical coupling mounted at one end of each tubing section, forming what is commonly referred to as a "female" end, while the other externally threaded end of the tubing section is referred to as a "male" end. Such tubing strings can be relatively efficiently assembled or disassembled using power tongs to screw additional tubing sections into the tubing string during an assembly operation, or to unscrew tubing sections from a tubing string being pulled from a wellbore (i.e., a breakout operation).

[0003] However, powered tongs do not simultaneously support other beneficial functions, such as rotation, pushing, or fluid filling, after a pipe section is added to or removed from the pipe string and as the pipe string is lowered or raised in the wellbore. Running tubulars with tongs (whether powered or manual) also typically requires the deployment of personnel in relatively high-risk locations, such as on the so-called "entry board" on and above the rig floor.

[0004] The advent of drilling rigs equipped with top drives has enabled another method of running tubing strings, particularly casing strings, using tools generally referred to as casing running tools or CRTs. These tools are configured to be carried by the top drive sleeve and to grip the upper end of the tubing section and to seal between the bore of the tubing section and the bore of the top drive sleeve. In coordination with the top drive, the CRT supports the lifting, rotation, pushing and filling of the casing string with drilling fluid while running the casing into the wellbore.

[0005] Ideally, these tools would also support make-up and break-out operations traditionally performed with power tongs, thereby eliminating the need for power tongs altogether, with the attendant benefits of reduced system complexity and increased safety. However, in practice, achieving these benefits without negatively impacting run rates or consistency requires that the time spent assembling a connection using a CRT be at least comparable to the run rates and consistency achievable with power tongs. Furthermore, it is a practical reality that using CRTs to make up a tubing string does increase the risk of damage to the connection threads, or the risk of seals in so-called "quality connections" that are present on the connection threads.

[0006] U.S. Patent No. 7,909,120 (Slack) teaches a CRT in the form of a gripping tool comprising a body assembly including:

[0007] a load adapter coupled for transmitting axial loads to the remainder of the body assembly and adapted to be structurally connected to a drive head or reaction frame;

[0008] a clamping assembly carried by the body assembly and having a clamping surface, wherein the clamping assembly is provided with an actuation means for radially stroking or moving the clamping surface from a retracted position to an engaged position in which the clamping surface tractionally engages an inner or outer surface of a tubular workpiece in response to relative axial movement or axial travel of the body assembly relative to the clamping surface in at least one direction; and

[0009] a linkage arrangement acting between the body assembly and the clamp assembly, wherein relative rotation of the load adapter with respect to the clamping surface in at least one direction causes axial displacement of the body assembly with respect to the clamp assembly to move the clamp assembly from the retracted position to the engaged position in response to action of the actuation arrangement.

[0010] For the purposes of this patent document, a CRT configured for gripping an inner surface of a tubular workpiece will be referred to as CRTi, and a CRT configured for gripping an outer surface of a tubular workpiece will be referred to as CRTe.

[0011] CRTs such as taught in U.S. 7,909,120 utilize a mechanically actuated clamping assembly that generates its clamping force in response to an axial load with a corresponding axial travel (along with or independently of an externally applied axial load and an externally applied torque load applied by right-hand or left-hand rotation.) When applied, these loads are carried from a load adapter of a body assembly across a tool to a clamping surface of the clamping assembly into pulling engagement with a workpiece.

[0012] In addition, such a CRT or clamping tool may be provided with a latching mechanism acting between the body assembly and the clamping assembly, the latching mechanism being in the form of a rotating J-slot latch having a hook receiving portion arrangement acting between a first latching member and a second latching member, wherein the first latching member is carried by the body assembly and the second latching member is carried by the clamping assembly (see, for example, U.S. Pat. No. 7,909,120). Figure 1and 14, showing latches in externally clamped and internally clamped full tool assemblies, respectively, and FIGS. 4 to 7 of U.S. Pat. No. 7,909,120, describing how matching latch teeth 108 and 110 function as hook and receiver relative to each other).

[0013] When in the first (or latched) position, the latch prevents relative axial movement between the body assembly and the clamp assembly with the hook in the receiver so as to maintain the clamp mechanism in the first (or retracted) position. However, relative rotation between the body assembly and the clamp assembly (which rotation is generally resisted by an amount of torque, which will be referred to herein as the "latch actuation torque") will cause the mating hook and receiver components to move to the second (or unlocked) position, thereby allowing relative axial movement between the body assembly and the clamp assembly, wherein the clamping surfaces are relative moved to the second (or engaged) position. Thus, when in the latched position, the latch mechanism will support operational steps that require maintaining the clamp assembly in its retracted position to enable positioning of the tool relative to the workpiece in preparation for engaging the clamping surfaces, and conversely maintain the clamping surfaces in their retracted position to enable separation of the CRT from the workpiece.

[0014] Operationally, achieving this relative movement with the CRT attached to the top drive sleeve requires sufficient reaction torque to be generated by the traction engagement when the "deck surface" of the CRT contacts the upper end of the tubular workpiece and applies an axial "sit-down" force to resist the latch actuation torque caused by the rotation applied to move the latch to the unlocked position (usually arranged as a right-hand rotation) and to cause axial movement if necessary (i.e., moving the hook up the "slot" of the J-slot). Any operational step that moves the latch from the latched position to the unlocked position is referred to as "firing" the tool, thereby allowing the tool to be "set".

[0015] To re-latch, the same requirement of having sufficient pulling resistance between the platform surface of the tool and the workpiece must be met where the torque applied is in the opposite direction (i.e., typically left-handed) to "unset" the tool. For mechanically set CRTs such as in U.S. 7,909,120, the pulling resistance required for re-latch is less than that required for un-setting.

[0016] U.S. Patent No. 9,869,143 (Slack) discusses how it is difficult to achieve sufficient traction resistance between the platform surface of a CRT and the workpiece in some applications, such as when the contacting surfaces of the CRT platform surface and the workpiece are both smooth steel, particularly when rotating to release a latch in such a tool. U.S. Patent No. 9,869,143 teaches a device for increasing the effective coefficient of friction acting between the workpiece and the tool under the application of a compressive load (i.e., the ratio of traction resistance to the applied load). Although these teachings disclose effective means for managing this operating variable and thereby reducing operational uncertainty, operation of the tool still requires the following steps: first setting a slightly controlled amount of axial load and then applying rotation using a top drive to move the latch to its unlocked position. Therefore, when the CRT is used in an assembly operation, the timing, load, and rotation control of performing these steps on certain drilling rigs can result in a slower cycle time than that achievable using a power tong for assembly.

[0017] The tubing sections in a tubing string are typically oriented "lower male, upper female." Thus, during the make-up operation, the upper end of the uppermost section in the string, supported by the rig floor slips or "chucks," presents itself as "upper female" in a so-called "pile" into which the male end of the next tubing section (i.e., the workpiece) penetrates. When using a CRT for make-up, it can be difficult to control the amount of top drive "make-up" load on the penetrated male threads and similarly the amount of rotation applied when the make-up load is present, introducing the possibility of an undesirable situation in which the male end of the workpiece rotates in the female threads in the pile before the threads of the male and female ends properly engage, with the attendant risk of wear damage to the threads. While these risks can be ameliorated by careful control of the top drive by the driller, they result in additional uncertainty and increased cycle times.

[0018] Therefore, there is a need for a method and apparatus for reducing the risk of thread damage when using a CRT for make-up and for providing greater assurance of cycle times comparable to or less than otherwise achievable using power tongs for make-up and casing running operations. Summary of the invention

[0019] The subject matter sought to be protected is set out in the accompanying independent and dependent claims.

[0020] In one aspect, the present disclosure describes a latch release mechanism having a longitudinal axis and acting between an upper latch assembly and a lower latch assembly that are coaxially aligned with the latch release mechanism. The upper latch assembly and the lower latch assembly are operable between a latched position (wherein relative axial separation of the upper latch assembly and the lower latch assembly is restrained) and an unlatched position (wherein relative axial movement of the upper latch assembly and the lower latch assembly is permitted within a limited range) in response to application of relative rotation and associated torque between the upper latch assembly and the lower latch assembly in a first rotational direction.

[0021] The upper latch assembly defines one or more trigger reaction pawl recesses and axially carries a generally cylindrical body assembly having a body bore. The latch release mechanism is coaxially disposed within the body bore and includes:

[0022] a damper element coupled to the lower latch assembly such that when the damper element moves axially relative to the lower latch assembly, the damper element will also rotate relative to the lower latch assembly; and

[0023] a trigger element coupled to the buffer element and the lower latch assembly so as to be at least axially movable relative to the buffer element and so as to be axially and rotationally movable within a defined range relative to the lower latch assembly, wherein the trigger element defines one or more trigger pawls configured for axial engagement and disengagement with the one or more trigger reaction pawl notches of the upper latch assembly;

[0024] Such that when the one or more trigger pawl teeth are disposed within the one or more trigger reaction pawl recesses:

[0025] Application of an axial force to the buffer element will tend to cause axial travel of the buffer element relative to the lower latch assembly so as to cause relative rotation between the upper latch assembly and the lower latch assembly in a first rotational direction to move the upper latch assembly and the lower latch assembly from a latched position to an unlatched position, wherein an associated torque is transmitted through the trigger element; and

[0026] • Application of additional axial force and resultant axial and rotational displacement of the buffer element relative to the lower latch assembly will cause one or more trigger pawls to withdraw from one or more trigger reaction pawl notches.

[0027] In general, the present disclosure describes a non-limiting embodiment of a rotary latch mechanism (alternatively referred to as a trigger mechanism) that includes an upper latch assembly and a lower latch assembly, and a latch release mechanism that includes an upper rotary latch component carried on the upper latch assembly and rotationally coupled to the upper latch assembly, and a lower rotary latch component carried on the lower latch assembly and rotationally coupled to the lower latch assembly. The upper rotary component and the lower rotary component are configured to move from a first (or axially latched) position to a second (or axially unlocked) position in response to rotation of the lower rotary component relative to the upper rotary component in a first (or unlocked) direction. This rotation causes the generation of an associated latch actuating torque.

[0028] The latch release mechanism has a movable platform element (alternatively referred to as a "guard bumper") that carries a downwardly facing platform surface that acts in response to relative axial displacement to promote relative rotation between an upper rotary latch component and a lower rotary latch component in order to apply a latch actuating torque required to move the latch components from a latched position to an unlatched position. In the case of a latch configuration that requires both relative axial compressive movement and rotation (such as is typically required for a J-slot latch), the mechanism can be configured so that axial movement of the movable platform element will cause both the relative axial movement required to release the latch as well as the required rotation. Thus, an exemplary embodiment according to the present teachings relates to a device for using externally controlled axial movement of a movable platform element carried by a latch release mechanism to cause the rotation and latch actuating torque required to move components forming a rotary latch from a latched position to an unlatched position without requiring externally induced rotation sufficient to move the mechanism from a latched position to an unlatched position.

[0029] By converting the relative axial motion between the tubular workpiece and the components of the tool in order to produce the relative rotation required to release the latch, the latch release mechanism as disclosed herein eliminates the need for externally applied rotation after applying a seat force when using a tool such as a mechanical CRT that employs a J-latch type mechanism to move from a first (latched) position to a second (unlatched) position. This enables a mechanical CRT equipped with such a latch release mechanism (or trigger mechanism) to produce comparable or shorter cycle times compared to using a power tong for such an operation, while reducing the risk of connecting thread damage when running casing.

[0030] This disclosure describes examples of rotary latch release mechanisms, including:

[0031] an upper latch assembly and a lower latch assembly, the upper latch assembly and the lower latch assembly being axially aligned;

[0032] an upper rotary latch component carried on and rotationally coupled to the upper latch assembly and a lower rotary latch component carried on and rotationally coupled to the lower latch assembly;

[0033] a bumper element defining a downwardly facing platform surface, wherein the bumper element is coupled to the lower latch assembly so as to be axially and rotationally movable relative to the lower latch assembly; and

[0034] a trigger element coupled to the buffer element and the lower latch assembly so as to be movable at least axially relative to the buffer element and axially and rotationally relative to the lower latch assembly;

[0035] in:

[0036] the upper rotary latch component and the lower rotary latch component being configured to move from an axially latched position to an axially unlatched position in response to relative rotation between the upper rotary latch component and the lower rotary latch component in a first rotational direction;

[0037] The upper latch assembly defines one or more downwardly facing trigger reaction pawl notches; and

[0038] the trigger element defining one or more upwardly facing trigger pawl teeth configured to engage with the one or more trigger reaction pawl recesses of the upper latch assembly;

[0039] The invention relates to a method for producing a latching device for latching a plurality of latches, wherein the latching device is a plurality of latch members, and the plurality of latch members are connected to each other via a plurality of latching mechanisms. The plurality of latch members are connected to each other via a plurality of latching mechanisms, and the plurality of latch members are connected to each other via a plurality of latching mechanisms.

[0040] The rotary latch release mechanism may include a first axially directed biasing device and a second axially directed biasing device, wherein the first axially directed biasing device acts between the upper latch assembly and the lower latch assembly to bias the latch release mechanism toward the latched position, and the second axially directed biasing device acts between the movable buffer element and the trigger element to bias the buffer element axially downward relative to the trigger element.

[0041] The upper latch assembly may define a downwardly facing upper ramp which may be cooperatively engaged with an upwardly facing lower ramp defined by the lower latch assembly such that application of an upward force to the platform surface of the buffer element will cause the upper ramp and the lower ramp to slide into engagement so as to constrain relative axial proximity of the upper latch assembly and the lower latch assembly while allowing relative rotation between the upper latch assembly and the lower latch assembly.

[0042] The present disclosure also describes an example of a rotary latch release mechanism that acts between (1) a generally cylindrical body having a body bore and (2) a generally cylindrical load adapter coaxially disposed within the body bore and axially and rotationally movable therein, wherein a lower end of the load adapter is operably engageable with an axially load-actuated latch linkage disposed within the body. In one embodiment, the latch release mechanism includes:

[0043] a load adapter extension coaxially mounted to an upper region of the load adapter and having a lower portion forming a skirt defining a first annular space between the load adapter extension and an outer cylindrical surface of the load adapter;

[0044] A main trigger element, the main trigger element having a main trigger hole, wherein:

[0045] The upper portion of the primary trigger element is coaxially disposed within the first annular space and is mounted to and carried by the skirt so as to be movable relative to the first annular space within defined constraints.

[0046] The skirt is axially and rotationally movable;

[0047] o The lower portion of the primary trigger element extends over the upper region of the body and can be

[0048] for axial movement of said upper region; and

[0049] o the primary trigger element carries a downwardly facing primary trigger reaction surface;

[0050] an auxiliary trigger element coaxially disposed in an auxiliary annular space defined by the skirt and the primary trigger element, wherein:

[0051] o the auxiliary trigger element is mounted to and carried by the skirt so as to move axially relative to the skirt within defined constraints but is non-rotatable relative to the skirt; and

[0052] o The auxiliary trigger element is coupled to the main trigger element so that within a defined range of about

[0053] The beam is axially and rotationally movable relative to the primary trigger element;

[0054] an auxiliary trigger extension having an auxiliary trigger extension hole and coaxially mounted to the lower end of the auxiliary trigger element;

[0055] a body extension coaxially and fixedly mounted to the outer cylindrical surface of the body, the body extension having a cylindrical upper portion coaxially disposed within the auxiliary trigger extension aperture, wherein:

[0056] o The inner and outer diameters of the cylindrical upper portion of the main body extension substantially correspond to those of the main

[0057] The inner and outer diameters of the trigger element;

[0058] o The cylindrical upper portion of the body extension defines an upwardly facing first reaction surface (alternatively referred to herein as an "upwardly facing jaw reaction surface") configured to engage the primary trigger

[0059] The reaction surfaces of the device are matingly engaged;

[0060] o an external shoulder defining an upwardly facing second reaction surface disposed on a lower region of the body extension;

[0061] o the body extension is axially movable relative to the auxiliary trigger extension and

[0062] capable of co-rotating with said auxiliary trigger extension; and

[0063] oThe lower end of the auxiliary trigger extension is configured to engage with the second reaction surface.

[0064] In this embodiment, the main trigger element and the auxiliary trigger element are configured such that an axial compressive load applied to the load adapter will be reacted through contact and engagement of the first reaction surface with the main trigger reaction surface and the second reaction surface with the auxiliary trigger extension, causing a corresponding axial displacement between the load adapter and the body, thereby causing rotation and axial movement of the auxiliary trigger element relative to the main trigger element, thereby generating torque and corresponding rotation to unlock the latch connection.

[0065] Optionally, in an alternative embodiment, a plurality of main trigger pawls may be provided on a downward facing reaction surface on the main trigger element, each main trigger pawl comprising a main trigger pawl load side, a main trigger pawl top and a main trigger pawl locking side, wherein a corresponding plurality of mating reaction pawl recesses are provided on an upward facing pawl reaction surface provided on the main body extension, each mating reaction pawl recess defining a reaction recess load side, a reaction recess top and a reaction recess locking side.

[0066] Several exemplary embodiments of a latch release mechanism according to the present disclosure are described below in the context of use with a CRT that utilizes a J-latch to maintain the clamping surface of the CRT in its retracted position and provides a means for triggering the J-latch by applying a seat-down load without the need for applying external rotational and latch actuating torques through a load adapter.

[0067] Example #1: Frictional Rotation Protection Buffer Under Casing Friction

[0068] (both CRTi and CRTe)

[0069] Embodiment #1 relies on pulling resistance to react to the latch actuation torque. In this embodiment, the latch release mechanism is carried by the lower latch assembly (including the clamping assembly of the CRT) and has a movable platform element (or protective bumper) having a generally downward facing platform surface adapted to engage the upper end of the tubular workpiece in pulling engagement. In response to contact with the tubular workpiece, upward axial compressive movement of the movable platform element relative to the lower rotary latch component causes the latch release mechanism to rotate the lower rotary latch component relative to the upper rotary latch component in an unlocking direction.

[0070] The latch release mechanism is further provided with a biasing means (such as but not limited to a spring) for biasing the platform surface to resist axial compressive displacement relative to the lower rotary latch member, thereby correspondingly generating a pulling resistance to rotational sliding between the platform surface and the tubular workpiece. So arranged, in a case where the upper rotary latch member and the lower rotary latch member are initially in the axially latched position, and in a case where the upper latch assembly (including the main assembly of the CRT) is supported by the load adapter to resist rotation relative to the tubular workpiece, the axial compressive movement transmitted to the upper rotary latch member by the load adapter relative to the tubular workpiece tends to cause rotation (and axial compressive travel, if required) of the lower rotary latch member relative to the upper rotary latch member, and in a case where the pulling resistance between the platform surface and the tubular workpiece is sufficient to exceed the latch actuation torque, the axial compressive movement causes rotation relative to the upper rotary latch member to move the lower rotary latch member to the unlocked position.

[0071] Example #2: Friction trigger between floating load adapter and body: CRTe with travel

[0072] Similar to embodiment #1, embodiment #2 relies on pull resistance to react to the latch actuation torque. In this embodiment, the upper latch assembly has a load adapter that is slidingly coupled to the body to carry axial loads while still allowing axial travel. The upper rotary latch component is axially carried by the body, but is rotationally coupled to the load adapter. The lower latch assembly is carried by the body and rotationally coupled to the body while allowing axial sliding through at least some range of motion when in the unlocked position. The lower latch assembly is also configured to carry a platform surface for contacting a tubular workpiece to support the seated load and provide pull resistance to rotation.

[0073] The latch release mechanism is carried by a selected one of the load adapter and the body and has a generally axially facing movable clutch surface adapted to be in traction engagement with an opposing reaction clutch surface on the other of the load adapter and the body. After the movable clutch surface is in contact and engagement with the reaction clutch surface, an axial compression stroke movement of the latch release mechanism, as driven by a seat force applied to the load adapter, causes the latch release mechanism to urge rotation between the load adapter and the body in an unlocking direction. The latch release mechanism is also provided with a biasing device (such as but not limited to a spring) for biasing the movable clutch surface to resist axial compression displacement relative to the component carrying the movable clutch surface (i.e., the load adapter or the body), thereby correspondingly generating a traction resistance to rotational sliding between the contacting movable clutch surface and the reaction clutch surface (or clutch interface).

[0074] So arranged, with the upper and lower rotary latch components initially in the axially latched position, and with the load adapter supported to generally allow free rotation relative to the body and thus the tubular workpiece, axial compressive movement within the axial travel allowance of the load adapter relative to the body tends to cause rotation (and axial compressive travel, if required) of the upper rotary latch component relative to the lower rotary latch component. In the event that the drag resistance of the clutch interface is sufficient to exceed the latch actuation torque (and possibly some external resistance torque of the generally freely rotating load adapter), the axial compressive movement causes rotation of the upper rotary latch component relative to the lower rotary latch component to move to the unlocked position.

[0075] With free rotation of the load adapter inhibited, the rotation driven by the seating load tends to promote slip at the clutch interface and at the platform-workpiece interface. Therefore, when a sufficient seating load is applied, the corresponding torques induced at these two interfaces will tend to cause slip on one interface or the other. If slip occurs on the platform-workpiece interface, the rotation required to release the latch will occur. However, if slip occurs at the clutch interface, relative rotation of the latch components will not occur, rendering the latch release mechanism ineffective for its intended purpose in these particular circumstances. Therefore, it may be advantageous to provide a means for increasing the torsional resistance of the clutch interface to increase the effective traction resistance under applied axial loads, such as by setting these mating surfaces as surfaces of a conical configuration to increase the normal force driving the rotational traction resistance for a given axial load. Such modifications may be provided in the absence of, or in combination with, profiling or other surface treatments to increase frictional resistance.

[0076] However, in all cases where it is desired to allow re-latching, if a seat load is required to achieve re-latching, the pulling resistance to rotation occurring at the clutch interface will tend to resist relative rotation of the upper and lower rotary latch components. For certain applications, the pulling response of these two interfaces can be reliably controlled by providing a selected combination of bias spring force, contact surface geometry, and surface treatment of the clutch and platform-to-workpiece surfaces, coordinated with load control that is sufficient to reliably prevent the clutch interface from slipping to support latch release rotation for a first compressive load, while allowing the clutch interface to slip without causing platform-to-workpiece slippage to support re-latching for a second selected compressive load combined with applied rotation.

[0077] As described above, embodiments #1 and #2 rely on the presence of sufficient pulling engagement between the contacting members to reliably unlock via the seating movement. In embodiment #1, the only limiting pulling resistance is between the tubular workpiece and the guard bumper, with the additional constraint that the latch actuation torque is further resisted by the external support that carries the upper latch assembly. To account for this, relative rotation between the upper rotary latch member and the tubular workpiece (at least in the unlocking direction) must be largely prevented to support the clamping engagement in the absence of externally applied rotation.

[0078] In embodiment #2, sufficient drag resistance of the clutch interface is required, typically with an additional constraint on the free rotation of the load adapter of the upper latch assembly. For applications where these boundary conditions can be easily and reliably met, embodiments #1 and #2 can provide the benefits of faster cycle times and reduced risk of connecting thread damage, as well as the benefits of relative mechanical simplicity. However, for applications where these boundary conditions cannot be easily achieved, a means for releasing the J-Latch independent of the available drag resistance or control of top drive rotation can be provided, as in the alternative embodiment described below.

[0079] Example #3: Latch Release Mechanism for "Basic Configuration": CRT with Latching Tri-Cam Assembly

[0080] Embodiment #3 is configured to force the upper rotary latch component and the lower rotary latch component to rotate relative to each other through a latch release mechanism. In this embodiment:

[0081] The upper rotary latch component is rigidly carried by the body of the upper latch assembly;

[0082] The lower rotary latch member is rotationally and axially constrained and carried by a lower latch assembly that acts in coordination with the body to prevent relative rotation and axial movement of the upper and lower rotary latch members when they are latched;

[0083] The latch release mechanism acts between the upper latch assembly and the lower latch assembly and includes four main elements, as follows:

[0084] o Latch triple cam assemblies as disclosed in International Publication No. WO2010 / 006441 (Slack) and U.S. Patent No. 8,424,939;

[0085] o a trigger reaction ring having one or more downwardly facing reaction pawl notches rigidly attached to the upper latch assembly;

[0086] o a trigger element carried by the lower latch assembly and having one or more upwardly facing trigger pawl teeth that generally mate and interact with the downwardly facing reaction pawl recess; and

[0087] o A movable platform element is also carried by the lower latch assembly and is provided with a generally downwardly facing platform surface adapted for axial compression engagement with the upper end of the tubular workpiece.

[0088] The movable platform element and the trigger element are coupled to each other and to the lower latch assembly such that upward axial compressive movement or travel of the movable platform element relative to the lower latch assembly from a first (or platform) position to a second (or fully traveled) position (such as driven by contact with the tubular workpiece) will drive rotation and downward axial movement of the trigger pawl. Initially, rotation of the trigger pawl is prevented by interaction with the reaction pawl notch, which causes the lower rotary latch component to rotate to its unlocked position relative to the upper rotary latch component, and when the movable platform element is fully traveled, the trigger pawl is fully retracted and disengaged from the reaction pawl notch. Retraction of the trigger pawl from the reaction pawl notch supports re-latching in the event of an external rotation applied in the re-latching direction. This embodiment preferably includes a biasing device that tends to resist axial compression of the movable platform element and retraction of the trigger element so that the platform element and the trigger element return to their initial positions when unloaded and withdrawn from the tubular workpiece.

[0089] Example #4: Retracting trigger acting between floating load adapter and body: CRTe with travel

[0090] Similar to embodiment #3, embodiment #4 is constructed to force the upper rotating latch component and the lower rotating latch component to rotate relative to each other through the latch release mechanism. In this embodiment:

[0091] The upper latch assembly includes a load adapter coupled to the body to carry axial loads while allowing axial travel;

[0092] The upper rotary latch member is axially carried by the body but rotationally coupled to the load adapter;

[0093] a lower latch assembly (including a clamping assembly for the CRT) carried by and rotationally coupled to the body while allowing axial movement through at least some range of motion when the latch is in its unlocked position; and

[0094] The lower latch assembly is also configured to carry a platform surface for contacting a tubular workpiece:

[0095] oSupport the sitting load;

[0096] o If the load adapter resists rotation during seating due to restrictions imposed by the top drive, the lower latch is achieved by sliding in contact with the workpiece

[0097] relative rotation between the assembly and the upper latch assembly; and

[0098] o Movement from the unlocked position to the latched position is achieved by providing traction resistance to rotation.

[0099] The latch release mechanism is configured to function between the sliding load adapter and the body, and similar to embodiment #3, the latch release mechanism includes three main elements:

[0100] a reaction claw pocket carried by a selected one of the load adapter and the body;

[0101] a primary trigger element having trigger dogs; and

[0102] • An auxiliary trigger element carried by the other of the load adapter and the body.

[0103] In the following discussion, it is assumed that the reaction pawl recess is upward facing and carried by the body, and that the primary trigger element (with downward facing trigger pawl teeth) and the auxiliary trigger element (with downward facing abutment surfaces) are carried by the load adapter. When the tool is in the latched position, the trigger pawl teeth and the reaction pawl recess are configured for aligned engagement when the load adapter is axially slidably moved downward through its axial travel, such as urged by contact with a tubular workpiece.

[0104] The upward facing reaction surface is also provided with a reaction pawl recess and is thus rigidly carried by the body and arranged to contact the downward facing abutment surface at an axial travel position lower than the axial travel position required for engagement of the trigger pawl with the reaction pawl recess. The auxiliary trigger element and the primary trigger element are coupled to each other and to the load adapter assembly such that downward axial compressive movement or travel of the abutment surface relative to the load adapter from a first (platform) position to a second (full travel) position (as actuated by contact with the tubular workpiece) will actuate rotation and upward axial movement of the trigger pawl.

[0105] Initially, rotation of the trigger pawl is prevented by interaction with the reaction pawl notch, which causes the lower rotary latch component to rotate relative to the upper rotary latch component to its unlocked position, and when the auxiliary trigger element is fully traveled, the trigger pawl will be fully retracted and disengaged from the reaction pawl notch, and such retraction of the trigger pawl will support re-latching in the event of an external rotation applied in the re-latching direction. This embodiment preferably includes a biasing device that tends to resist axial compression of the auxiliary trigger element and retraction of the primary trigger element so that the primary and auxiliary trigger elements return to their initial positions upon unloading and withdrawal from the tubular workpiece.

[0106] In order to further support reverse rotation under a sitting load to achieve re-latching as required, the auxiliary trigger element can be configured as an auxiliary trigger assembly, which includes an auxiliary trigger extension having a downwardly facing seat surface, threadedly connected to the auxiliary trigger element but rotationally keyed to the body, so that rotation in the unlocking direction tends to move the seat surface lower, resulting in compressive engagement of the seat surface and the reaction surface at an axially higher position, which prevents the trigger pawl from prematurely engaging the reaction pawl recess until the rotational position for re-latching has been reached.

[0107] Example #5: Internal Trigger CRTe

[0108] In embodiment #5, the latch release mechanism has a longitudinal axis and acts between an upper latch assembly and a lower latch assembly, the upper latch assembly and the lower latch assembly being coaxially aligned with the latch release mechanism, and wherein:

[0109] (a) in response to application of relative rotation and associated torque between the upper latch assembly and the lower latch assembly in a first rotational direction, the upper latch assembly and the lower latch assembly are operable between the following positions:

[0110] A latched position, in which the upper latch assembly and the lower latch

[0111] Relative axial separation of the components is restrained; and

[0112] An unlocked position in which the upper latch assembly and the lower

[0113] Relative axial movement of the latch assembly within a limited range;

[0114] (b) the upper latch assembly defines one or more trigger reaction pawl notches; and

[0115] (c) the upper latch assembly axially carries a generally cylindrical body assembly having a body bore;

[0116] wherein the latch release mechanism is coaxially disposed within the body bore and comprises:

[0117] (d) a buffer element coupled to the lower latch assembly such that when the buffer element moves axially relative to the lower latch assembly, the buffer element will also rotate relative to the lower latch assembly; and

[0118] (e) a trigger element coupled to the buffer element and the lower latch assembly so as to be at least axially movable relative to the buffer element and so as to be axially and rotationally movable within a defined range relative to the lower latch assembly, wherein the trigger element defines one or more trigger pawls configured for axial engagement and disengagement with the one or more trigger reaction pawl notches of the upper latch assembly;

[0119] Such that when the one or more trigger pawl teeth are disposed within the one or more trigger reaction pawl recesses:

[0120] Application of an axial force to the buffer element will tend to cause axial travel of the buffer element relative to the lower latch assembly so as to cause relative rotation between the upper latch assembly and the lower latch assembly in a first rotational direction to move the upper latch assembly and the lower latch assembly from a latched position to an unlatched position, wherein an associated torque is transmitted through the trigger element; and

[0121] • Application of additional axial force and resultant axial and rotational displacement of the buffer element relative to the lower latch assembly will cause one or more trigger pawls to withdraw from one or more trigger reaction pawl notches.

[0122] In a variant embodiment, the latch release mechanism may further include an overrunning clutch (i.e., a clutch that transmits torque in one rotational direction but not in an opposite rotational direction), which is configured such that torque applied to the buffer element in a first rotational direction will be transmitted through the latch release mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0123] Embodiments will now be described with reference to the accompanying drawings, wherein reference numerals refer to like parts, and wherein:

[0124] Figure 1 A prior art gripper-internal casing running tool (CRTi) is shown, which corresponds substantially to the tool shown in Figures 48 and 49 of US 8,424,939.

[0125] Figure 2A and 2B They are Figure 1 Isometric and cross-sectional views of a prior art CRTi equipped with an embodiment of a latch release mechanism according to the present disclosure.

[0126] Figure 3A and Figure 3B Schematic front and isometric views, respectively, of an exemplary embodiment of a latch release mechanism according to the present disclosure, the latch release mechanism being shown in a latched position and an unloaded position.

[0127] Figure 4A and 4B They are Figure 3A and 3B Schematic front and isometric views of the latch release mechanism in FIG. 1 , showing the situation after the application of an axial load causes axial movement to initiate the latch release sequence.

[0128] Figure 5A and Figure 5B They are Figure 3A and Figure 3B Schematic front and isometric views of the latch release mechanism in FIG. 1 , shown after an axial load is applied to cause the latch release mechanism to travel so as to cause rotational movement sufficient to release the latch.

[0129] Fig. 6A and Figure 6B They are Figure 3A and Figure 3B Front and isometric views of the latch release mechanism in FIG. 1 , showing the situation after an axial load is applied to cause the latch release mechanism to travel so as to cause axial movement sufficient to withdraw the latch.

[0130] Fig. 7A and Figure 7B They are Figure 3A and Figure 3B Front and isometric views of the latch release mechanism in FIG, shown after rotation to re-latch the latch and after the axial load is sufficiently reduced to partially reset the latch release mechanism.

[0131] Fig. 8A It passes through Figure 2A and 2B Cross-section of the triple-cam latch linkage and latch release mechanism of the modified CRTi tool in FIG, shown in the latched and unloaded positions.

[0132] Figure 8B It passes through Figure 2A and 2B Cross-section of the latch release mechanism of the modified CRTi tool in FIG, shown in the latched and unloaded position.

[0133] Fig.9A Is through Fig. 8A A cross section of a triple cam latch linkage and latch release mechanism in FIG, shown after an axial load has been applied to cause the latch release mechanism to travel in order to cause rotational movement sufficient to release the latch.

[0134] Fig. 9B It passes through Figure 8B A cross-section of the latch release mechanism in FIG. 1 , shown after an axial load has been applied to cause the latch release mechanism to travel to cause rotational movement sufficient to release the latch.

[0135] Fig. 10A It passes through Fig. 8A A cross section of the triple cam latch linkage and latch release mechanism in FIG. 1 is shown after sufficient axial load has been applied to cause the latch release mechanism to travel in order to retract the trigger pawl.

[0136] Fig. 10B It passes through Figure 8B A cross-section of the latch release mechanism in FIG. 1 , shown after sufficient axial load has been applied to cause the latch release mechanism to travel in order to retract the trigger pawl.

[0137] Fig.11A It passes through Fig. 8A Cross section of the triple cam latch linkage and latch release mechanism in FIG, shown after rotation to re-latch the latch release mechanism.

[0138] Fig. 11B It passes through Fig. 8A A cross section of the latch release mechanism in FIG. 1 , shown after being rotated to re-latch the latch release mechanism.

[0139] Fig.12 A CRTi is shown equipped with a latch release mechanism according to an embodiment of the present disclosure.

[0140] Fig.13A It passes through Fig.12 Cross section of the triple-cam latch linkage and latch release mechanism of the modified CRTi.

[0141] Fig. 13B It passes through Fig.13A Cross section of the latch release mechanism in .

[0142] Fig.14A It passes through Fig.13A and 13B Cross-section of the triple-cam latch linkage and latch release mechanism of the modified CRTi shown in the latched and unloaded positions.

[0143] Fig. 14B It passes through Fig.14A Cross section of the latch release mechanism in .

[0144] Fig.15 is a cross section through a prior art CRTe.

[0145] Fig.16 is a cross-section of a prior art externally gripped casing running tool (CRTe) equipped with an embodiment of a latch release mechanism according to the present disclosure.

[0146] Fig.17A and 17B It passes through Fig.16 Cross section of the triple cam latch linkage and latch release mechanism in FIG, shown in the initial latched position.

[0147] Fig.18A and 18B It passes through Fig.17A and 17B A cross section of the triple cam latch linkage and latch release mechanism in is shown after application of sufficient seat load and corresponding displacement to cause axial downward movement of the floating load adapter extension.

[0148] Fig.19A and 19B It passes through Fig.18A and 18B A cross section of the triple-cam latch linkage and latch release mechanism in FIG, shown after continued application of a sit-down load and corresponding displacement tending to unlock the latch linkage.

[0149] Fig. 20A and 20B It passes through Fig.19A and 19B A cross section of the triple cam latch linkage and latch release mechanism in is shown after further application of a seat down load and corresponding displacement which tends to disengage the trigger pawl from the reaction pawl recess to allow relative rotation between the body assembly and the floating load adapter.

[0150] Fig.21A and 21B It passes through Fig. 20A and 20B A cross section of the triple cam latch linkage and latch release mechanism in is shown after sufficient axial squat load has been applied to unlock the triple cam latch linkage, where the floating load adapter has been moved upward to remove the squat load.

[0151] Fig.22A and 22B It passes through Fig.21A and 21B Cross section of the triple cam latch linkage and latch release mechanism in FIG, showing right hand rotation of the floating load adapter causing engagement of the standoff surface on the auxiliary trigger extension moving downwardly toward the reaction surface on the main body extension.

[0152] Fig.23A and 23B It passes through Fig.22A and 22B Cross section of the triple cam latch linkage and latch release mechanism in FIG, showing the right-hand rotation applied after the seat load and corresponding displacement to disengage the trigger pawl from the reaction pawl notch.

[0153] Fig.24A and 24B It passes through Fig.23A and 23B Cross section of the triple cam latch linkage and latch release mechanism in FIG, showing the sit-down load that is reapplied to re-latch the latch linkage.

[0154] Fig.25A and 25B It passes through Fig.24A and 24B Cross section of the triple cam latch linkage and latch release mechanism in FIG. 1 , showing the latch linkage in the re-latched position.

[0155] Fig.26 is a cross section through an external gripper casing running tool (CRTe) internally configured with an embodiment of a latch release mechanism according to the present disclosure and an embodiment of a variable length axial linkage according to US Pat. No. 11,560,761 (Slack).

[0156] Fig. 27 yes Fig.26 Front view of the CRTe’s variable length axial linkage and latch release mechanism.

[0157] Fig.28 yes Fig. 27 An isometric view of the variable length axial linkage and latch release mechanism in FIG. 1 , wherein the latch release mechanism is shown in an exploded view.

[0158] Fig.29A It passes through Fig. 27 Cross section of the variable length axial linkage and latch release mechanism in FIG, showing the hidden trigger spring, with the lower portion of the drive cam body cut away to show the trigger pawl and the trigger reaction pawl recess, and the variable length axial linkage in the latched position.

[0159] Fig.29B yes Fig. 27 A front view of the variable length axial linkage and latch release mechanism in FIG, showing the hidden trigger spring, with the lower portion of the drive cam body cut away to show the trigger pawl and the trigger reaction pawl recess, with the drive cam body and retainer extension cut away, and with the variable length axial linkage in the latched position.

[0160] Fig. 30A It passes through Fig. 27 A cross section of the variable length axial linkage and latch release mechanism in FIG, showing the hidden trigger spring, with the lower portion of the drive cam body cut away to show the trigger pawl and trigger reaction pawl recess, and the latch release mechanism travel sufficient to move the variable length axial linkage to the unlocked position.

[0161] Fig. 30B yes Fig. 27 A front view of the variable length axial linkage and latch release mechanism in FIG, showing the hidden trigger spring, with the lower portion of the drive cam body cut away to expose the trigger pawl and trigger reaction pawl recess, with the drive cam body and retainer extension sectioned away, and the latch release mechanism fully stroked to move the variable length axial linkage to the unlocked position.

[0162] Fig.31A It passes through Fig. 27 A cross section of the variable length axial linkage and latch release mechanism in FIG, showing the hidden trigger spring, with the lower portion of the drive cam body cut away to expose the trigger pawl and the trigger reaction pawl recess, and the latch release mechanism fully advanced to retract the trigger pawl from the trigger reaction pawl recess.

[0163] Fig.31B yes Fig. 27 A front view of the variable length axial linkage and latch release mechanism in FIG, showing the trigger spring hidden, with the lower portion of the drive cam body cut away to expose the trigger pawl and trigger reaction pawl recess, with the drive cam body and retainer extension sectioned away, and the latch release mechanism fully advanced to retract the trigger pawl from the trigger reaction pawl recess.

[0164] Fig.32A It passes through Fig. 27 Cross section of the variable length axial linkage and latch release mechanism in FIG, showing the hidden trigger spring, with the lower portion of the drive cam body cut away to show the trigger pawl and trigger reaction pawl recess, and the lower latch assembly rotated relative to the upper latch assembly to re-latch the variable length axial linkage.

[0165] Fig.32B yes Fig. 27 A front view of the variable length axial linkage and latch release mechanism in FIG, showing the hidden trigger spring, wherein the lower portion of the drive cam body is cut away to expose the trigger pawl and the trigger reaction pawl recess, wherein the drive cam body and retainer extension are sectioned, and wherein the lower latch assembly is rotated relative to the upper latch assembly to re-latch the variable length axial linkage. DETAILED DESCRIPTION

[0166] Figures 1 to 25B Taken from International Publication No. WO2020 / 146936 and described herein to provide background information, when reading this article with reference to Figures 26 to 32B This background information may be helpful to the reader when describing exemplary embodiments of a latch release mechanism.

[0167] Figure 1 48 and 49 of U.S. Pat. No. 8,424,939. The CRT 100 includes a body assembly 110, a clamp assembly 120, and a holder 500 linked to the clamp assembly 120. The CRT 100 is provided in a Figure 1 1 and 2. In the embodiment of the present invention, the clamping assembly 120 is shown in a latched position and inserted into a tubular workpiece 101 (shown in a partial cross-sectional view). In the latched position, relative axial movement between the main body assembly 110 and the clamping assembly 120 is prevented so that the clamping assembly 120 remains in its retracted position.

[0168] The upper end of the body assembly 110 is provided with a load adapter 111, which is shown by way of non-limiting example as having a conventional tapered threaded connection 112 for structural connection to a top drive sleeve (not shown) of a drilling rig (not shown). The clamping assembly 120 includes a deck surface 122 carried by a fixed bumper 121 rigidly attached to a holder 500 of the clamping assembly 120. As described in U.S. Pat. No. 8,424,939 (but not shown herein), the body assembly 110 carries an upper rotary latch component, and the clamping assembly 120 carries a lower rotary latch component that is linked to the holder 500 so as to be generally fixed against rotational and axial movement relative to the holder 500 when in a latched position, but is configured to be rotationally moved to an unlocked position in response to a generally right-handed rotation of the body assembly 110 relative to the clamping assembly 120, wherein a latch actuating torque corresponding to the rotational movement is reacted by the traction engagement of the deck surface 122 with the tubular workpiece 101.

[0169] Figure 2A shows that it usually corresponds to Figure 1 CRTi130 of CRT100 in FIG. 1 , but modified to incorporate an embodiment of a rotary latch release mechanism (optionally referred to herein as a trigger mechanism) according to the present disclosure. Figure 2A In this particular embodiment, the CRTi130 includes a latch release mechanism 201 (shown schematically in the following figures) comprising:

[0170] an upper rotary latch component provided in the form of a trigger reaction ring 204 rigidly carried by the body assembly 110 and having one or more downwardly facing trigger reaction pawl notches 205, wherein each trigger reaction pawl notch 205 is generally defined by a reaction notch load side 206, a reaction notch top 207, and a reaction notch locking side 208;

[0171] A trigger element 210 having one or more upwardly facing trigger pawls 211, wherein each trigger pawl 211 is generally defined by a trigger pawl load side 212, a trigger pawl top 213, and a trigger pawl locking side 214, wherein when the latch release mechanism 201 is in a position such as Figure 2A In the latched position shown, each trigger pawl tooth 211 engages a corresponding trigger reaction pawl notch 205; and

[0172] A movable bumper 218 having a movable platform surface 220 , wherein the trigger element 210 and the movable bumper 218 are carried by a lower rotary latch component provided in the form of a cage extension 222 rigidly coupled to the cage 500 .

[0173] The retainer extension 222, trigger element 210 and movable buffer 218 are generally configured as a coaxial nested set of close-fitting cylindrical components, wherein relative rotational and translational motion between these components is constrained to maintain their coaxial alignment, but are also linked by cam pairs in the manner of cam followers and cam surfaces, as described later herein.

[0174] Figure 3A and 3B , Figure 4A and 4B , Figure 5A and 5B , Fig. 6A and 6B as well as Fig. 7A and 7B The schematic diagram shows the operational relationship of the various components of the latch release mechanism 201 in sequential stages of the operation of the latch release mechanism 201. Although the latch release mechanism 201 is a three-dimensional rotating assembly, the basic components of the latch release mechanism 201 are shown in Figure 2 to facilitate a clear understanding of the structure and operation of the latch release mechanism 201. FIG. 3A to FIG. 7B , shown in a roughly two-dimensional schematic manner, with the tangential (rotational) direction transposed to the horizontal direction and the axial direction transposed to the vertical direction.

[0175] Figure 3A and 3BThe latch release mechanism 201 is shown in relation to the schematically shown CRT, still in the fully latched position, with the schematically shown tubular workpiece 101 disposed slightly below the movable bumper 218. Reference numeral 301 designates an upper latch assembly rigidly coupled to the body assembly 110 of the CRT, and having a trigger reaction pawl recess 205 and an upper rotary latch receiver 302. Reference numeral 310 designates a lower latch assembly, which includes a retainer extension 222 incorporating a lower rotary latch hook 312, which is shown in a latched position relative to the upper rotary latch receiver 302. The upper latch assembly 301 carries an internal upper cam ramp 303, which is shown nearly in contact with an internal lower cam ramp 304 on the retainer extension 222, with an internal biasing spring 305 disposed and acting between the body assembly 110 and the retainer extension 222. These features are shown to represent the internal reactions and forces operable between the body assembly 110 and the clamp assembly 120 of the CRT to facilitate understanding of the function of the CRT in coordination with the latch release mechanism 201 .

[0176] The holder extension 222 carries a movable bumper 218 having a movable platform surface 220 and a trigger element 210. The movable bumper 218 is connected to the trigger element 210 by a bumper-trigger cam follower 314, which is rigidly fixed to the movable bumper 218 and is movable within an axially oriented bumper-trigger cam slot 315 (having an upper end 316 and a lower end 317) formed in the trigger element 210, so that the movable bumper 218 is axially movable relative to the trigger element 210. The buffer-retainer cam follower 318 rigidly fixed to the retainer extension 222 is constrained to move within a buffer-retainer cam groove 319 formed in the movable buffer 218 (wherein the buffer-retainer cam groove 319 has an upper end 320 and a lower end 321); and the trigger-retainer cam follower 322 rigidly fixed to the retainer extension 222 is constrained to move within a trigger-retainer cam recess 324 provided in the trigger element 210.

[0177] Although the specific and exemplary arrangements of the components of the latch release mechanism 201 are described above and are Figure 3A and Figure 3B, but it will be apparent to those skilled in the art that the choice of securing the cam follower to one or the other of the two components to be mated and the cam profile to the other component is arbitrary with respect to the relative movement constraints and corresponding degrees of freedom associated with such a mechanism. Similarly, the choice of cam follower / cam surface as a means for providing the desired movement constraints is not intended to be limiting in any way. Those skilled in the art will readily appreciate that substantially equivalent mechanisms may be provided in other forms without departing from the intended scope of the present disclosure.

[0178] In the illustrated embodiment, the buffer-trigger cam slot 315 is configured as an axially oriented slot that closely matches the diameter of the associated buffer-trigger cam follower 314 and thus has a single degree of freedom to allow only relative axial sliding movement between the trigger element 210 and the movable buffer 218 without allowing relative rotation, wherein the trigger biasing spring 326 is configured to act between the trigger element 210 and the movable buffer 218 in the direction of axial sliding to bias the movable buffer 218 downwardly relative to the trigger element 210. The buffer-holder cam slot 319 is inclined at a selected angle relative to the vertical direction (by Figure 3A and Figure 3B 45 degrees) and is closely matched to the diameter of the associated bumper-retainer cam follower 318 to provide a single degree of freedom that couples the relative axial movement of the movable bumper 218 to the rotation of the retainer extension 222. However, free movement of the trigger-retainer cam follower 322 is permitted within the trapezoidal trigger-retainer cam recess 324, constrained only by contact of the cam constraining surfaces against the perimeter defining the trigger-retainer cam recess 324, as shown below:

[0179] A trigger advancing cam surface 330 that defines a horizontal lower edge of the trigger-retainer cam recess 324;

[0180] A trigger retraction cam surface 332 defining an angled right edge of the trigger-retainer cam recess 324, angled at a selected angle from the vertical;

[0181] A trigger re-latch cam surface 334 that defines the horizontal upper edge of the trigger-retainer cam recess 324; and

[0182] • A trigger reset cam surface 336 which defines the vertical left edge of the trigger-retainer cam recess 324 .

[0183] During typical operation, the operating state of the latch release mechanism 201 can be characterized with reference to the position of the trigger-retainer cam follower 322 within the trigger-retainer cam recess 324 as follows:

[0184] Starting position: The trigger-retainer cam follower 322 is near the intersection of the trigger reset cam surface 336 and the trigger advance cam surface 330 (eg, Figure 3A , 3B , 4A and 4B);

[0185] Advance position: The trigger-retainer cam follower 322 is near the intersection of the trigger advance cam surface 330 and the trigger retract cam surface 332 (eg, Figure 5A and 5B shown);

[0186] Withdrawn position: the trigger-retainer cam follower 322 is proximate the intersection of the trigger withdrawal cam surface 332 and the trigger re-latch cam surface 334; and

[0187] Reset position: The trigger-retainer cam follower 322 is near the intersection of the trigger re-latch cam surface 334 and the trigger reset cam surface 336 .

[0188] When the latch release mechanism 201 is in the latched position (eg Figure 3A and Figure 3B 324 ), the buffer-retainer cam follower 318 is positioned toward the upper end 320 of the buffer-retainer cam slot 319, and the trigger-retainer cam follower 322 is urged by the trigger biasing spring 326 toward the starting position within the trigger-retainer cam recess 324. At the same time, the trigger biasing spring 326 maintains the engagement of the trigger pawl 211 within the trigger reaction pawl recess 205, which can position the trigger pawl locking side 214 to be closely opposed to the reaction notch locking side 208 of the trigger reaction pawl recess 205, as in the illustrated embodiment, so as to prevent the upper latch assembly 301 from accidentally rotating relative to the lower latch assembly 310, as controlled by the selection of the mating side angles and clearances, wherein a more vertically inclined angle is selected to more strongly resist rotation for a given trigger biasing spring 326 force.

[0189] It is apparent that the upper rotary latch receiver 302 and lower rotary latch hook 312 (configured as a J-shaped slot requiring axial displacement) already provide some protection against accidental rotation. However, for the type of J-shaped latch commonly employed in CRTs, where no axial displacement is required and only torque is allowed to unlock, the trigger pawl locking profile 214 and the mating reaction notch locking profile 208 provide the additional benefit of preventing accidental rotation.

[0190] In actual operation of the rotary latch release mechanism, as the CRTi 130 is lowered, a contact force of the tubular workpiece 101 reacting against the movable platform surface 220 tends to build up. FIG. 3A to FIG. 7B For purposes of the description herein, the upper latch assembly 301 will be considered a reference, wherein the tubular workpiece 101 is considered to tend to move upward relative to the upper latch assembly 301 and, accordingly, tend to push the movable platform surface 220 upward (rather than downward as in actual operation).

[0191] Reference now Figure 4A and Figure 4B , wherein the force of the trigger biasing spring 326 is sufficient to prevent relative movement between the components of the latch release mechanism 201, the force applied to the movable platform surface 220 will be transmitted to the retainer extension 222, wherein upward movement is resisted until the force of the internal biasing spring 305 is overcome, resulting in upward movement of the entire lower latch assembly 310, and correspondingly causing the lower rotary latch hook 312 to move axially upward relative to the upper rotary latch receiver 302. This upward movement is limited by the contact between the internal upper cam ramp 303 and the internal lower cam ramp 304, as shown. Figure 4A and 4B shown.

[0192] While this upward movement causing axial separation of the lower rotary latch hook 312 from the upper rotary latch receiver 302 is not a desired movement of the J-latch type typically used for all CRTs, as will be known to those skilled in the art, the mating lower rotary latch hook 312 and upper rotary latch receiver 302 may alternatively be configured to disengage solely in response to an applied torque.

[0193] Regardless of whether the applied load is first sufficient to overcome the force of the internal biasing spring 305, when the tubular workpiece 101 applies sufficient force to overcome the force of the trigger biasing spring 326, the movable bumper 218 will move upward, causing the bumper-retainer cam follower 318 to move downward within the inclined bumper-retainer cam slot 319, as shown. Figure 5A and 5BAs shown. The upward movement of the movable buffer 218 tends to cause rotation of the retainer extension 222, but such rotation is resisted by the actuation torque acting between the upper latch assembly 301 and the lower latch assembly 310. This torque is transmitted through the movable buffer 218 via the buffer-retainer cam follower 318 and the cam slot 319 to the trigger element 210, and through the trigger pawl load side 212 to the reaction notch load side 206, and from there back to the upper latch assembly 301, thereby reacting the latch actuation torque internally and causing the trigger-retainer cam follower 322 to move along the trigger advance cam surface 330 to an advanced position within the trigger-retainer cam notch 324, thereby moving the rotary latch to its unlocked position, as shown. Figure 5A and 5B This movement is shown as a right-hand rotation of the upper latch assembly 301 relative to the lower latch assembly 310.

[0194] As reference Fig. 6A and 6B As will be appreciated, further upward movement of the movable bumper 218 continues to urge rotation of the retainer extension 222, thereby causing: (1) movement of the trigger-retainer cam follower 322 to a withdrawn position within the trigger-retainer cam recess 324, (2) resultant downward movement of the trigger element 210, and (3) corresponding withdrawal of the trigger pawl 211 from engagement with the trigger reaction pawl recess 205. The angle of inclination of the trigger withdrawal cam surface 332 of the trigger-retainer cam recess 324 is selected relative to the orientation of the bumper-retainer cam slot 319 to facilitate withdrawal of the trigger pawl 211 without binding or otherwise causing excessive force, taking into account the force of operating the trigger biasing spring 326 and frictional forces that would otherwise tend to affect the withdrawal motion. Furthermore, it is apparent that with the trigger element 210 withdrawn from the trigger reaction ring 204, the upper latch assembly 301 is free to rotate relative to the lower latch assembly 310, and more specifically, allows left-hand rotation of the upper latch assembly 301 relative to the lower latch assembly 310 to re-latch the tool.

[0195] This rotation supports movement of the lower rotary latch hook 312 into engagement with the upper rotary latch receiver 302 (i.e., the latched position), wherein the corresponding actuation torque is resisted by the drag engagement of the movable platform surface 220 with the tubular workpiece 101. However, in general, the portion of the seating load carried by the contact between the inner upper cam ramp 303 and the inner lower cam ramp 304 (as a function of the associated cam ramp angles) tends to require less drag engagement for this re-latch movement than would be required for unlatching in tools having different types of latch release mechanisms.

[0196] Reference now Fig. 7A and Figure 7B , it can be seen that when the operating step of removing the tool from the tubular workpiece 101 causes the upward axial force acting on the movable platform surface 220 to decrease, the trigger biasing spring 326 pushes the movable bumper 218 downward and correspondingly causes the movable bumper 218 to rotate relative to the retainer extension 222, possibly with associated sliding at the interface between the movable platform surface 220 and the tubular workpiece 101, and produces a pulling friction force that acts in the direction of retaining the latch. This movement of the movable bumper 218 and the force from the trigger biasing spring 326 tends to push the trigger element 210 to reverse the withdrawal movement just described, thereby causing the trigger pawl 211 to move upward. However, this upward movement is prevented when the trigger pawl top 213 slidingly engages the reaction notch top 207, thereby forcing the trigger-retainer cam follower 322 to move from the withdrawn position toward the reset position within the trigger-retainer cam notch 324.

[0197] As the movable bumper 218 continues to move downward, following the movement of the tubular workpiece 101, it reaches a point where the trigger pawl tooth top 213 no longer engages (i.e., slides off) the reaction notch top 207, thereby allowing the trigger-retainer cam follower 322 to move from the reset position and return toward the starting position within the trigger-retainer cam notch 324, thereby returning the latch release mechanism 201 to the reset position. Figure 3A and Figure 3B The operating state shown, in which the tool is ready to start again Figure 3A and FIG. 3B to FIG. 7A and Figure 7B The sequence of operations shown.

[0198] CRTi Embodiment

[0199] Figure 2B A CRTi 130 is shown that has been modified to incorporate an exemplary embodiment of a latch release mechanism 131 according to the present disclosure, and a triple cam latch linkage 132 as generally disclosed in US Pat. No. 8,424,939. Fig. 8A and 8B , Fig.9A and 9B , Fig. 10A and 10B as well as Fig.11A and 11B Sequential stages of operation of the latch release mechanism 131 are shown.

[0200] exist Figure 2BIn the illustrated embodiment, the improved CRTi 130 includes a main body assembly 110 including a load adapter 111 for structural connection to a top drive casing of a drilling rig (not shown), a clamping assembly 120 including a retainer 500 and a jaw 123, a latch release mechanism 131, and a triple cam latch linkage 132. The triple cam latch linkage 132 includes an upper latch assembly 133 fixed to and carried by the main body assembly 110, and a lower latch assembly 134 fixed to and carried by the clamping assembly 120.

[0201] like Fig. 8A As shown, the latch release mechanism 131 includes an upper latch assembly 133, which includes a drive cam body 400 carrying a plurality of drive cam latch hooks 401 and a drive cam housing 420, wherein the drive cam body 400 is rigidly constrained to the main body assembly 110 of the CRTi130. The latch release mechanism 131 also includes a lower latch assembly 134, which includes a follower cam body 470, a follower cam housing 480, and a latch cam 490, wherein the latch cam 490 has a plurality of latch cam latch hooks 491 and is rigidly constrained to the clamp assembly 120 of the CRTi130. The three-cam latch mechanism 132 also includes an intermediate cam body 430, which has a load thread 431 on an inner surface, and the load thread 431 engages with the load thread 402 on the outer surface of the drive cam body 400.

[0202] The drive cam body-housing seal 403, the drive cam body-spindle seal 404, the drive housing-follower housing seal 421, the drive cam body-retainer seal 472 and the retainer spindle seal 501 define an annular piston area and a gas spring chamber 422. When pressurized with gas, the gas spring chamber 422 forms an internal gas spring that tends to urge the upper latch assembly 133 and the lower latch assembly 134 to separate, thereby tending to urge the body assembly 110 and the clamp assembly 120 to separate to move the latch release mechanism 131 between the first (unlocked) position and the second (latched) position. This separation is resisted by the matingly engaged drive cam latch hook 401 and latch cam latch hook 491, which can be disengaged by applying sufficient right-hand torque (i.e., latch actuation torque) and corresponding right-hand rotation of the body assembly 110 relative to the clamp assembly 120. When the drive cam latch hook 401 and the latch cam latch hook 491 are engaged, the three-cam latch linkage 132 is considered to be in the latched position, and when the drive cam latch hook 401 and the latch cam latch hook 491 are disengaged, the three-cam latch linkage 132 is considered to be in the unlocked position.

[0203] refer to Figure 8BThe following section describes in detail a mechanism that can be used to generate the right-hand torque and rotation required to unlock the triple-cam latch linkage 132 using only axial compression and corresponding axial displacement, Figure 8B 1 is a cross section through the latch release mechanism 131, which is shown in the latched position. For the purpose of discussing this mechanism, the body assembly 110 will be considered as a reference, and the tubular workpiece 101 will be considered to tend to move upward.

[0204] like Figure 8B As shown in FIG. 1 , the latch release mechanism 131 includes a trigger reaction ring 410 fixed to the body assembly 110, a trigger element 440, a trigger biasing spring 449, a movable bumper 450 having a movable platform surface 451, a bumper cam follower 452, and a retainer extension 460 fixed to the clamp assembly 120. The components of the latch release mechanism 131 and the three-cam latch linkage 132 are generally configured as a coaxial nested set of close-fitting cylindrical components, wherein the relative rotational and translational movement between these components is constrained to first hold them in coaxial alignment.

[0205] In operation, the CRTi 130 with the latch release mechanism 131 will first be inserted or "dipped" into the tubular workpiece 101 and lowered until the movable platform surface 451 contacts the tubular workpiece 101 and the contact force generated by the tool weight and the seat load applied by the top drive (not shown) increases above the "trigger seat load", at which time the latch release mechanism 131 has applied the required latch actuation torque and the displacement required to disengage the drive cam latch hook 401 and the latch cam latch hook 491. The gas spring will cause the axial displacement of the body assembly 110 relative to the clamp assembly 120, thereby transforming the CRTi 130 together with the latch release mechanism 131 from the retracted position to the engaged position. This operating sequence differs from the CRT 100 in two ways:

[0206] • First, the CRTi 130 with latch release mechanism 131 does not require externally applied right-hand rotation to transition between the retracted position and the engaged position, which simplifies the operating procedure.

[0207] • Second, the latch release mechanism 131 is designed so that it does not rely on a pulling engagement between the movable platform surface 451 and the tubular workpiece 101; instead, the latch actuating torque is reacted internally, thereby reducing operational uncertainty.

[0208] As reference Fig. 10BAs best understood, the trigger reaction ring 410 has one or more downward facing trigger reaction pawl notches 411, each of which is generally defined by a reaction notch load side 412, a reaction notch top 413, and a reaction notch locking side 414, wherein each trigger reaction pawl notch 411 is engageable with a corresponding upward facing trigger pawl 441. Each trigger pawl 441 is generally defined by a trigger pawl load side 442, a trigger pawl top 443, and a trigger pawl locking side 444 (when the tool is in the latched position, as shown in FIG. Figure 8B 4. The movable bumper 450 and the trigger element 440 are coupled by a bumper cam follower 452, which is fixed to the movable bumper 450 and is movable within a trigger cam slot 445 provided in the trigger element 440 between an upper end 446 and a lower end 447 of the trigger cam slot 445. In addition, the movable bumper 450 is coupled to a retainer extension 460 by the bumper cam follower 452, which is constrained to move within a bumper-retainer cam slot 461 between an upper end 462 and a lower end 463 thereof. The trigger element 440 is coupled to the retainer extension 460 by a trigger cam follower 448, which is fixed to the trigger element 440 and constrained to move within a retainer cam recess 464 provided in the retainer extension 460. In addition, the retainer extension 460 is rigidly fixed to a follower cam body 470.

[0209] It will be apparent to those skilled in the art that the cam follower may be secured to either of the two components to be mated, with the cam profile defined in the other of the two paired components, and that design choices in this regard will generally be based on practical considerations, such as efficiency of assembly, disassembly and maintenance. Similarly, the selection of a cam follower / cam surface as a means for providing the desired movement restriction is not intended to be limiting in any way, with those skilled in the art understanding that substantially equivalent mechanisms may be provided in other forms.

[0210] exist Figure 8B In the illustrated embodiment, the trigger cam slot 445 is configured as an axially oriented slot that mates closely with the buffer cam follower 452, thereby generally providing a single degree of freedom to allow relative axial movement between the trigger element 440 and the movable buffer 450, but not relative rotation. The trigger biasing spring 449 is configured to act between the trigger element 440 and the movable buffer 450 in the direction of axial sliding to bias the movable buffer 450 downward. The buffer-holder cam slot 461 is inclined at a selected angle relative to the vertical direction (by Figure 8B45 degrees) and mates with the associated bumper cam follower 452 to provide a single degree of freedom that couples the relative axial movement of the movable bumper 450 to the rotation of the retainer extension 460. However, the free movement of the trigger cam follower 448 is permitted within the trapezoidal retainer cam recess 464, constrained only by contact with the cam surfaces that define the perimeter of the retainer cam recess 464, as follows:

[0211] An advancing cam surface 466 that defines a flat upper edge of the retainer cam recess 464;

[0212] An exit cam surface 467 that forms a helical path; and

[0213] • A reset cam surface 469 which defines an axially oriented side edge of the retainer cam recess 464 .

[0214] During typical operation, the operating state of the latch release mechanism 131 can be characterized with reference to the position of the trigger cam follower 448 within the retainer cam recess 464 as follows:

[0215] Starting position: the trigger cam follower 448 is near the intersection of the reset cam surface 469 and the advance cam surface 466;

[0216] Advance position: the trigger cam follower 448 is near the intersection of the advance cam surface 466 and the exit cam surface 467;

[0217] Retracted position: the trigger cam follower 448 is proximate to the exit cam surface 467; and

[0218] Reset position: the trigger cam follower 448 is close to the reset cam surface 469.

[0219] When the latch release mechanism is in Figure 8B In the case of the latched position shown, with the buffer cam follower 452 positioned at the lower end 463 of the buffer-retainer cam slot 461, the trigger biasing spring 449 will push the trigger cam follower 448 toward the starting position in the retainer cam recess 464 while keeping the trigger pawl 441 engaged in the corresponding trigger reaction pawl recess 411. This engagement of the trigger pawl 441 sets the trigger pawl locking side 444 in close opposition to the corresponding reaction recess locking side 414 to prevent accidental rotation of the upper latch assembly 133 relative to the lower latch assembly 134, as controlled by the selection of the mating side angles and clearances. If desired, a more axially aligned cam surface can be selected to more strongly resist rotation for a given force applied by the trigger biasing spring 449.

[0220] Now refer to Fig. 9B When the tubular workpiece 101 applies sufficient force to overcome the force of the trigger biasing spring 449, the movable buffer 450 moves upward, causing the buffer cam follower 452 to move axially upward within the buffer-retainer cam slot 461. This axial upward axial movement tends to rotate the retainer extension 460, but this rotation is resisted by the latch actuation torque acting between the upper latch assembly 133 and the lower latch assembly 134, which is transmitted through the movable buffer 450 via the buffer cam follower 452 and the trigger cam slot 445 to the trigger element 440, and is transmitted through the trigger pawl load side 442 to the reaction notch load side 412 and to the upper latch assembly 133. This causes the latch actuating torque to react internally and causes the trigger cam follower 448 to move along the advancing cam surface 466 to an advanced position within the retainer cam recess 464, thereby disengaging the drive cam latch hook 401 from the latch cam latch hook 491 and, through right-hand rotation of the upper latch assembly 133 relative to the lower latch assembly 134, changing the state of the three-cam latch linkage 132 from as shown Fig. 8A The latch position in the Fig.9A in the unlocked position.

[0221] Once the drive cam latch hook 401 and the latch cam latch hook 491 have disengaged, the gas spring urges the upper latch assembly 133 to separate from the lower latch assembly 134. It is at this point in the operating sequence of casing running that a combination of axial tension and rotation will be applied during the connection assembly process to cause right-hand rotation of the upper latch assembly 133 relative to the lower latch assembly 134. During this stage of operation, the latch release mechanism 131 will not interfere with the normal function of the casing running tool.

[0222] Further upward movement of the movable bumper 450 continues to force rotation of the retainer extension 460 and, therefore, forces the trigger cam follower 448 to move to a withdrawn position within the retainer cam recess 464, thereby moving the trigger element 440 downward and, in turn, withdrawing the trigger pawl 441 from engagement with the trigger reaction pawl recess 411, as shown in FIG. Fig. 10B The angle of the exit cam surface 467 relative to the angled bumper-retainer cam slot 461 can be selected so as to facilitate withdrawal of the trigger pawl 441 from engagement with the trigger reaction pawl recess 411 without binding or otherwise causing forces that exceed the operating trigger bias and friction forces that would otherwise tend to affect the withdrawal motion.

[0223] like Fig. 10BAs shown in , with the trigger element 440 withdrawn from the trigger reaction ring 410, the trigger pawl locking side 444 is no longer opposite the reaction notch load side 412, so the upper latch assembly 133 can be rotated relative to the lower latch assembly 134 to re-latch the three-cam latch linkage 132. Fig.11A As shown, such rotation of the upper latch assembly 133 relative to the lower latch assembly 134 causes the latch cam latch hook 491 to move into engagement with the drive cam latch hook 401 (i.e., latched position), wherein the corresponding actuating torque caused by such rotation is resisted by the traction engagement of the movable platform surface 451 with the tubular workpiece 101.

[0224] Reference now Fig. 11B , with the CRTi130 thus in the re-latched position, since the operational step of removing the CRTi130 from the tubular workpiece 101 reduces the axial force acting on the movable platform surface 451, the trigger biasing spring 449 pushes the movable bumper 450 downward and correspondingly rotates the movable bumper 450 relative to the holder extension 460, with possible accompanying sliding between the movable platform surface 451 and the tubular workpiece 101. Therefore, the traction friction force from the trigger biasing spring 449 tends to push the trigger element 440 to reverse the above-mentioned withdrawal movement, thereby moving the trigger pawl 441 upward. However, this upward movement of the trigger pawl 441 is prevented by the sliding engagement of the trigger pawl top 443 with the reaction notch top 413, forcing the trigger cam follower 448 to move from the withdrawn position to the reset position within the holder cam notch 464. As the movable bumper 450 continues to move downward, following the movement of the tubular workpiece 101, it reaches a point where the trigger pawl tops 443 no longer engage (i.e., they slide off) the reaction notch tops 413, thereby allowing the trigger cam follower 448 to move from the reset position to the start position within the retainer cam notch 464, thereby returning the latch release mechanism 131 to the reset position. Fig. 8A The position shown can be repeated from this position Figures 8A to 11B The order of operations shown.

[0225] Friction / Inertia CRTi Example

[0226] A latch release mechanism will now be described which relies on drag resistance between the movable platform surface 451 of the movable bumper 450 and the tubular workpiece 101 in quasi-static operation. The latch release mechanism is a modification of the latch release mechanism 131 previously described herein under the heading "CRTi Embodiment." As used in this disclosure, the phrase "quasi-static operation" with respect to the latch release mechanism should be understood to refer to the operation of the mechanism such that axial loads are applied in a sufficiently slow manner such that the dynamic effects associated therewith are minimal or negligible.

[0227] Fig.12 is a cross-sectional view of a CRTi135 equipped with a three-cam latch linkage 132 and a latch release mechanism 136, the latch release mechanism 136 being carried by a lower latch assembly 134 and including a movable buffer 450, a buffer cam follower 452 fixed to the movable buffer 450, a trigger bias spring 520 and a retainer extension 510, which are generally constructed as a set of coaxially nested, tightly fitting cylindrical components in which relative rotational and translational motion between these components is constrained so as to maintain their coaxial alignment. Fig.12 The triple cam latch linkage 132, movable buffer 450 and buffer cam follower 452 in the embodiment are similar to those previously described under the heading "CRTi Embodiment" and described in detail in the accompanying drawings. Fig. 8A and 8B The same as those depicted in .

[0228] As reference Fig.13A and Fig. 13B As best understood, the movable bumper 450 and the holder extension 510 are coupled by a bumper cam follower 452 which is movable within a holder cam slot 511 disposed in the holder extension 510 and between an upper end 512 and a lower end 513 of the holder cam slot 511. The holder cam slot 511 is angularly spaced relative to the longitudinal axis of the tool (via a plurality of apertures). Fig. 13B 45 degrees) and is closely mated with an associated buffer cam follower 452 that defines a translation-rotation relationship between the movable buffer 450 and the retainer extension 510. Additionally, the retainer extension 510 is rigidly fixed to the follower cam body 470, and a trigger biasing spring 520 is provided to act between the retainer extension 510 and the movable buffer 450 to bias the movable buffer 450 axially downwardly, and to bias the buffer cam follower 452 to contact the lower end 513 of the retainer cam slot 511.

[0229] It will be apparent to those skilled in the art that the buffer cam follower 452 may be secured to either of the two components to be mated, with the cam profile defined in the other of the paired components. Design choices in this regard will generally be based on practical considerations, including efficiency of assembly, disassembly, and maintenance. Similarly, the selection of a cam follower / cam surface as a means for providing the desired movement restriction is not intended to be limiting in any way; those skilled in the art will appreciate that functionally effective alternative mechanisms may be provided in other forms.

[0230] For purposes of this discussion, the body assembly 110 will be considered a reference and the tubular workpiece 101 will be considered to tend to move upward relative to the reference. Fig.13A and 13B As shown, when the three-cam latch linkage 132 is in the latched position, the buffer cam follower 452 will be positioned at the lower end 513 of the retainer cam slot 511 due to the axial downward force applied by the trigger bias spring 520. In operation, the CRTi135 with the latch release mechanism 136 will be lowered until the movable platform surface 451 on the movable buffer 450 contacts the tubular workpiece 101 and the contact force generated by the tool weight and the seat load applied by the top drive (not shown) increases to above the "trigger seat load", at which time the latch release tubular workpiece 136 will apply the required latch actuation torque and the rotation required to disengage the drive cam latch hook 401 from the latch cam latch hook 491.

[0231] like Fig.14A and 14B As shown, when the tubular workpiece 101 applies sufficient force in a quasi-static manner to overcome the force of the trigger bias spring 520, the movable buffer 450 will move upward, generating a torque between itself and the retainer extension 510 due to the interaction of the buffer cam follower 452 within the retainer cam groove 511, and for the movable buffer 450, this torque must be reacted by the traction engagement of the movable platform surface 451 with the tubular workpiece 101, which, if sufficient, will cause rotation of the retainer extension 510.

[0232] Rotation of the cage extension 510 will be resisted by the latch actuation torque acting between the upper latch assembly 133 and the lower latch assembly 134. The latch actuation torque will be transmitted from the upper latch assembly 133 to the load adapter 111 and in turn must be reacted by the top drive, thereby disengaging the drive cam latch hook 401 from the latch cam latch hook 491 and causing the three-cam latch linkage 132 to rotate from the upper latch assembly 133 to the lower latch assembly 134 through right-hand rotation. Fig.13A The latch position shown moves to Fig.14A Once the drive cam latch hook 401 and the latch cam latch hook 491 have disengaged, the gas spring associated with the latch release mechanism 136 (generally as previously described with reference to the latch release mechanism 131) will push the upper latch assembly 133 to separate from the lower latch assembly 134.

[0233] It will be apparent to one skilled in the art that the described latch release mechanism 136 will be capable of generating the latch actuation torque and corresponding rotation required to move the CRTi 135 from the disengaged position to the engaged position solely by quasi-static application of an axial seating load and displacement, provided that the following two boundary conditions can be readily satisfied:

[0234] 1. The pulling engagement between the movable platform surface 451 and the tubular workpiece 101 is sufficient to react the latch actuation torque; and

[0235] 2. The top drive has sufficient torque resistance to react against the latch actuation torque.

[0236] Where the above two conditions can be easily and reliably met, the latch release mechanism 136 can provide the benefits of faster cycle times, operational simplicity, and relative mechanical simplicity.

[0237] In addition, the nature of the tool operation can be exploited to supplement the traction engagement between the movable platform surface 451 and the tubular workpiece 101, i.e., the movable buffer 450 can be designed to have a high moment of inertia about the tool axis relative to the combined moment of inertia of the retainer extension 510 and the clamping assembly 120, and when the seat load is applied at a sufficient speed, the retainer extension 510 and the clamping assembly 120 will have a greater tendency to accelerate rotationally, resulting in right-hand rotation of the upper latch assembly 133 relative to the lower latch assembly 134 and disengaging the drive cam latch hook 401 from the latch cam latch hook 491.

[0238] To disengage the CRTi from the tubular workpiece 101, a seat load and a left-hand torque are applied to the load adapter 111 and reacted between the movable bumper 450 and the tubular workpiece 101. When the seat load and the left-hand torque are sufficient, the upper latch assembly 133 will rotate in the left-hand direction relative to the lower latch assembly 134, causing the drive cam latch hook 401 to move into engagement with the latch cam latch hook 491 (i.e., into the latched position), wherein the corresponding torque caused by this rotation is resisted by the pulling engagement of the movable platform surface 451 with the tubular workpiece 101.

[0239] The operation step of removing the CRTi135 from the tubular workpiece 101 will reduce the axial force acting on the movable platform surface 451, wherein the trigger biasing spring 520 pushes the movable buffer 450 downward and correspondingly rotates the movable buffer 450 relative to the retainer extension 510, possibly accompanied by sliding between the movable platform surface 451 and the tubular workpiece 101 and the resulting traction friction force acting in the direction of retaining the latch. With the tubular workpiece 101 moved axially downward sufficiently, the buffer cam follower 452 will contact the lower end 513 of the retainer cam slot 511, thereby returning the latch release mechanism 136 to Fig.13A The position shown can be repeated from this position Figures 13A to 14B The order of operations shown.

[0240] CRTe Example

[0241] Fig.15 is a cross-sectional view of a prior art external gripping casing running tool (CRTe) 140 including a body assembly 150 having a body upper housing 151 rigidly secured to a body lower housing 152, a floating load adapter 160 for structural connection to a top drive casing shaft of a drilling rig (not shown), a clamping assembly 170 rigidly carrying a bumper 171, and a triple cam latch linkage 180 including an upper latch assembly 181 axially secured to the body assembly 150 and a lower latch assembly 183 secured to and carried by the clamping assembly 170. The upper latch assembly 181 is rotationally coupled to the floating load adapter 160 and includes a drive cam 184 carrying a plurality of drive cam latch hooks 185 plus a drive cam housing 186. The lower latch assembly 183 includes a follower cam 187 plus a latch cam 188 that carries a plurality of latch cam latch hooks 189 .

[0242] like Fig.15 As shown, the upper cam-housing seal 190, the body-housing upper seal 191, the lower cam-housing seal 192, the body-housing lower seal 193, the lower cam-retainer seal 194 and the upper cam-retainer seal 195 define a gas spring chamber 196, wherein the lower cam-housing seal 192 and the upper cam-retainer seal 195 define a piston area carried by the lower latch assembly 183. When pressurized with gas, the gas spring chamber 196 forms an internal gas spring that tends to urge the upper latch assembly 181 to separate from the lower latch assembly 183, thereby tending to urge the body upper housing 151 to separate from the clamping assembly 170 to move the CRTe 140 from the retracted position to the engaged position relative to the tubular workpiece 101.

[0243] This separation is resisted by the matingly engageable drive cam latch hook 185 and latch cam latch hook 189, which can be disengaged by applying sufficient right-hand torque (i.e., latch actuation torque) and corresponding right-hand rotation of the floating load adapter 160 relative to the body assembly 150. In the prior art CRTe 140, the latch actuation torque is applied by the floating load adapter 160 and reacted by the pulling engagement between the tubular workpiece 101 and the platform surface 172 disposed on the bumper 171. When the drive cam latch hook 185 and the latch cam latch hook 189 are engaged, the three-cam latch linkage 180 is considered to be in the latched position, and when the drive cam latch hook 185 and the latch cam latch hook 189 are disengaged, the three-cam latch linkage 180 is considered to be in the unlocked position.

[0244] Also like Fig.15 As shown, the floating load adapter 160 has a floating load adapter upper axial shoulder 161 that allows axial tension loads to be transferred by contacting the axial shoulder 154 of the body assembly 150. In addition, the floating load adapter 160 has a floating load adapter lower axial shoulder 162 that allows axial compression loads to be transferred by contacting the axial shoulder 182 on the upper latch assembly 181, which in turn transfers the axial compression load to the body upper housing 151. The axial distance between the axial shoulder 154 on the body upper housing 151 and the axial shoulder 182 on the upper latch assembly 181 is greater than the axial distance between the upper axial shoulder 161 and the lower axial shoulder 162 on the floating load adapter 160, thereby providing an axial range through which the floating load adapter 160 can move without transferring axial tension or compression loads to the body assembly 150.

[0245] Fig.16 shows CRTe197, which corresponds essentially to Fig.15 The prior art CRTe140 is a CRTe140 of the prior art, but is equipped with a prior art latch release mechanism 198 which can be used to generate the right-hand torque (i.e., latch actuating torque) and rotation required to unlock the triple-cam latch linkage 180 using only axial compression and corresponding axial displacement, thereby allowing the CRTe197 to be converted from a retracted position to an engaged position and then returned to the retracted position to facilitate repeated casing assembly and lifting processes involved in constructing oil and gas wells.

[0246] Fig.16 The CRTe 197 is shown in a latched position. The prior art latch release mechanism 198 comprises:

[0247] A load adapter extension 163 secured to the floating load adapter 160 and including a downwardly extending skirt 165;

[0248] A primary trigger element 600 (alternatively referred to as primary trigger 600 ) coaxially disposed within the load adapter extension 163 ; a trigger biasing spring 618 ;

[0249] Auxiliary trigger element 620 (alternatively referred to as auxiliary trigger 620);

[0250] Auxiliary trigger extension 630;

[0251] A main body extension 640;

[0252] Clamping ring 650; and

[0253] Main body lock 660.

[0254] The components of the prior art latch release mechanism 198 are typically configured as a coaxially nested set of close-fitting generally cylindrical components, wherein relative rotational and translational motion between the components is constrained to maintain their coaxial alignment, as will be described in more detail below.

[0255] In operation, the CRTe 197 will first be inserted or "shoved" onto the tubular workpiece 101, and the contact force generated by the tool weight and the seat load applied by the top drive (not shown) will increase, resulting in a corresponding axial displacement between the body assembly 150 and the floating load adapter 160, enabling the latch release mechanism 198 to generate the required latch actuation torque and corresponding rotation to unlock the three-cam latch linkage 180, wherein the gas spring causes the axial displacement between the clamp assembly 170 and the body assembly 150, thereby transitioning the CRTe 197 from the initial retracted position to the engaged position. This operating sequence of the CRTe 197 differs from the operation of the prior art CRTe 140 in two respects:

[0256] First, the CRTe197 does not require externally applied right-hand rotation to transition between the retracted and engaged positions, thus simplifying the operation process.

[0257] • Second, the latch release mechanism 198 of the CRTe 197 is configured such that it does not rely on a pulling engagement between the platform surface 172 and the tubular workpiece 101; instead, the latch actuating torque is reacted internally, thereby reducing operational uncertainty.

[0258] The following discussion describes how the prior art latch release mechanism 198 generates a latch actuation torque and corresponding rotation solely through seating load and axial displacement.

[0259] Fig.17Ais a cross section through the CRTe 197, wherein the clamping assembly 170, the tubular workpiece 101 and the main body lower housing 152 are hidden for clarity, and Fig. 17B 1 is a cross section through the latch release mechanism 198 of the CRTe 197, shown in two views in an initial latched position. The load adapter extension 163 is rigidly fixed to the floating load adapter 160 by one or more load adapter lugs 164, and rigidly carries one or more load adapter cam followers 601, each of which is constrained to move within a primary trigger cam slot 606 provided by the primary trigger 600 and within an auxiliary trigger cam slot 621 provided by the auxiliary trigger 620. The primary trigger cam slot 606 also has a vertical lower portion 608 adjacent to the upper portion 607. The upper portion 607 of the primary trigger cam slot 606 is inclined from the vertical at a selected angle (which angle can vary along the length of the upper portion 607). Therefore, the relative axial and rotational movement between the load adapter extension 163 and the primary trigger 600 is defined by the upper portion 607 and the lower portion 608 of the primary trigger cam slot 606.

[0260] The auxiliary trigger cam slot 621 is axially oriented and closely fits to the load adapter cam follower 601, thereby coupling the rotation of the load adapter extension 163 and the auxiliary trigger 620. The auxiliary trigger cam slot 621 has a lower end 623 plus an upper end 622, and the load adapter cam follower 601 is biased to contact the upper end 622 by the trigger bias spring 618, which acts between the auxiliary trigger 620 and the load adapter extension 163 to apply an axial downward biasing force to the auxiliary trigger 620. Therefore, the relative axial movement between the load adapter extension 163 and the auxiliary trigger 620 is constrained within the upper end 622 of the auxiliary trigger cam slot 621 and the lower end 623 of the auxiliary trigger cam slot.

[0261] The auxiliary trigger 620 rigidly carries one or more auxiliary trigger cam followers 624, each of which is tightly fitted within a claw retraction cam slot 612 provided on the main trigger 600. Each claw retraction cam slot 612 has an upper end 613 that is circumferentially oriented and constrains the auxiliary trigger 620 and the main trigger 600 to be initially axially coupled, and transitions to a lower end 614 that is inclined from the vertical at a selected angle (which angle can vary along the length of the lower end 614) and tightly fits to a corresponding auxiliary trigger cam follower 624 to define a translation-rotation relationship between the auxiliary trigger 620 and the main trigger 600. Therefore, relative axial and rotational movement between the auxiliary trigger 620 and the main trigger 600 is constrained within the upper end 613 and the lower end 614 of the claw retraction cam slot 612.

[0262] Still reference Fig.17A and 17B , the auxiliary trigger extension 630 has an auxiliary trigger extension thread 632 having a defined spiral line in the left-hand direction, which engages the auxiliary trigger thread 625 provided on the auxiliary trigger 620. In addition, the auxiliary trigger extension 630 has an auxiliary trigger extension lug 633, which fits tightly into the axially oriented groove 647 provided on the main body extension 640 to couple the rotation of the main body extension 640 and the auxiliary trigger extension 630. The main body lock 660 is held fixed to the main body upper housing 151 by the main body lock lug 661. The clamping ring 650 is axially bolted to the body lock 660, wherein the axial load generated by the bolting is transferred into the clamping ring load shoulder 651 provided on the clamping ring 650, transferred to the body extension load shoulder 648 provided on the body extension 640, and in turn acts between the body extension locking surface 649 and the upper housing locking surface 153 provided on the body assembly 150, which engagement allows the body extension 640 to tractionally resist torsional loads that may be generated by the latch release mechanism 198. So arranged, the body extension 640 can first be assembled to the body assembly 150 and rotationally positioned, and then the clamping ring 650 can be secured, effectively rigidly connecting the body extension 640 to the body assembly 150.

[0263] like Fig. 17B As shown, a plurality of primary trigger pawls 602 may be provided on a downward facing primary trigger reaction surface 615 on the primary trigger 600, each primary trigger pawl 602 including a primary trigger pawl load side 603, a primary trigger pawl top 604, and a primary trigger pawl locking side 605, wherein a corresponding plurality of mating reaction pawl recesses 642 are provided on an upward facing pawl reaction surface 646 on the body extension 640, each mating reaction pawl recess 642 defining a reaction recess load side 643, a reaction recess top 644, and a reaction recess locking side 645. In the illustrated embodiment, the primary trigger pawls 602 are initially rotationally aligned with the corresponding mating reaction pawl recesses 642 but axially separated.

[0264] Fig.18A is a cross-sectional view of CRTe197, and Fig.18Bare cross-sectional views of a latch release mechanism 198 of the prior art, both of which are shown after contact between the tubular workpiece 101 and the buffer 171 has been established and sufficient axial seating load and corresponding displacement have been generated to cause the load adapter extension 163, floating load adapter lug 164, main trigger 600, load adapter cam follower 601, auxiliary trigger 620, auxiliary trigger cam follower 624 and auxiliary trigger extension 630 to translate axially downward until the main trigger pawl tooth top 604 and its corresponding reaction recess top 644 begin to contact, at which time the support surface 631 set on the auxiliary trigger extension 630 approaches but does not contact the second reaction surface 641 set on the main extension 640.

[0265] refer to Fig.19A and 19B , the load and corresponding displacement of continued seating will cause the main trigger 600 to begin to move axially upward and rotate in a right-hand direction tending to unlock the three-cam latch linkage 180 due to the constraint applied to the main trigger 600 by the engagement of the load adapter cam follower 601 in the upper portion 607 of the main trigger cam slot 606. This rotation causes the main trigger pawl load side 603 to engage the reaction notch load side 643, thereby generating a torque on the body extension 640 in a direction tending to unlock the three-cam latch linkage 180. The torque applied to the body extension 640 is resisted by the pulling engagement between the body extension locking surface 649 and the upper housing locking surface 153 and is transmitted into the body assembly 150. It will now be apparent that the latch release mechanism 198 is capable of generating a torque and corresponding rotation in a direction tending to unlock the three-cam latch linkage 180 simply by applying a seating load and displacement.

[0266] Reference now Fig. 20A and 20B , further seating load and corresponding axial displacement will cause the auxiliary trigger cam follower 624 to engage the pawl retracting the lower end 614 of the cam slot 612. This engagement tends to move the primary trigger pawl 602 axially upward relative to the body extension 640, thereby transmitting an axial seating load that initially reacts between the primary trigger pawl top 604 and the reaction notch top 644 to react between the seat surface 631 and the second reaction surface 641. With sufficient seating load and corresponding displacement, the primary trigger pawl 602 will become completely disengaged from the reaction pawl notch 642, thereby allowing relative rotation between the body assembly 150 and the floating load adapter 160 in either direction.

[0267] Fig.21A and Fig. 21B197 and latch release mechanism 198, both shown after sufficient seating load has been applied to unlock the triple cam latch linkage 180, whereupon the floating load adapter 160 has moved axially upward, thereby removing the axial seating load. At this point, right-hand (or left-hand) rotation may be applied to the floating load adapter 160 to make (or break) the casing string connection. Fig.22A and 22B As shown, applying a right-hand thread between the floating load adapter 160 and the main body assembly 150 will cause the support surface 631 to move axially downward due to the left-hand thread formed by the auxiliary trigger extension thread 632 and the auxiliary trigger thread 625, and this downward axial movement will in turn cause the support surface 631 to engage the second reaction surface 641 at a relatively high axial position of the floating load adapter 160.

[0268] Alternatively, if Fig.23A and 23B As shown, instead of moving the floating load adapter 160 axially upward and then applying the right-hand rotation, the right-hand rotation may be applied immediately after the axial seating load and corresponding displacement are sufficient to disengage the primary trigger pawl 602 from the corresponding reaction pawl recess 642. In this case, the seat surface 631 engages the second reaction surface 641, and applying the right-hand rotation to the floating load adapter 160 will produce an axially upward force and corresponding displacement of the auxiliary trigger 620. The axially upward displacement of the auxiliary trigger 620 causes the load adapter cam follower 601 to engage the lower portion 608 of the primary trigger cam slot 606.

[0269] In either case, right-hand rotation will cause the abutment surface 631 to move axially downward, and when the seating load is reapplied to re-latch the triple cam latch linkage 180, the abutment surface 631 will engage the second reaction surface 641, thereby preventing the primary trigger pawl 602 from re-engaging the reaction pawl recess 642 and thereby supporting the application of torque and rotation in the left-hand direction, thereby tending to re-latch the triple cam latch linkage 180, as shown. Fig.24A and 24B With the triple cam latch linkage 180 in the latched position, the clamp assembly 170 will now be retracted from the tubular workpiece 101 while the bumper 171 remains in contact with the tubular workpiece 101 .

[0270] Fig.25A and 25BThe CRTe197 is shown in a re-latched position. When the operational step of removing the CRTe197 from the tubular workpiece 101 reduces the axial force acting on the platform surface 172, the trigger bias spring 618 pushes the auxiliary trigger 620 downwardly and correspondingly causes the main trigger 600 to rotate in a left-hand direction and move axially downward relative to the floating load adapter 160. However, the downward movement of the main trigger 600 is hindered by the sliding engagement of the main trigger pawl tooth tops 604 and the pawl reaction surface 646. As the floating load adapter 160 continues to move upward, a point is reached where the main trigger pawl tooth tops 604 no longer engage (i.e., they slide off) the pawl reaction surface 646, thereby allowing the main trigger pawl 602 to re-engage the reaction pawl recess 642. Further axial upward movement of the floating load adapter 160 will cause the main trigger pawl 602 to rotationally align but axially separate from the reaction pawl recess 642, thereby returning the latch release mechanism 198 to the re-latched position. Fig.17A and Fig. 17B The position shown can be repeated from this position FIG. 17A to FIG. 25B The order of operations shown.

[0271] With reference to the previous description of the operation of the prior art latch release mechanism 198, it will be apparent to those skilled in the art that:

[0272] The shape of the master trigger cam slot 606 determines the relationship between relative rotational movement and axial movement between the load adapter extension 163 and the master trigger 600; and

[0273] The angle of the primary trigger cam slot 606 from vertical may be selected to vary along its length to coordinate relative rotation and axial movement and control contact and internal stresses generated when the latch release mechanism 198 is actuated.

[0274] It is obvious to those skilled in the art that:

[0275] The main trigger cam groove 606 of CRTe197 is functionally equivalent to FIG. 3A to FIG. 7B The bumper-cage cam groove 319 of the exemplary embodiment shown, Figure 8B , Fig. 9B , Fig. 10B and Fig. 11B The buffer-cage cam groove 461 of the CRTi130 shown and Fig. 13B and Fig. 14B The cage cam groove 511 of the CRTi135 shown; and

[0276] ·Slot 319, buffer-retainer cam slot 461 and retainer cam slot 511 can be selected to change the angle of the buffer-retainer cam along its respective length from the vertical in the same manner as the main trigger cam slot 606 to coordinate relative rotation and axial movement and control the contact stress and internal stress generated when the corresponding latch release mechanism is actuated.

[0277] Internal Trigger CRTe Embodiment

[0278] Fig.26 is a cross section through an external gripping casing running tool (CRTe) 1000 configured to grip a tubular workpiece 1001. The CRTe 1000 has a longitudinal axis and comprises:

[0279] An axially extending linkage (which in the illustrated embodiment is shown as an embodiment of a variable length axial linkage 1100 according to U.S. 11,560,761, but which in alternative embodiments may be a different type of axially extending linkage, such as but not limited to a triple cam latch linkage as previously described herein);

[0280] · An embodiment of a latch release mechanism 1200 according to the present disclosure;

[0281] A body assembly 1300 having a body aperture 1301; and

[0282] The clamping assembly 1400 is coaxially disposed within the body hole 1301 of the body assembly 1300 .

[0283] Fig. 27 is a front view of the variable length axial linkage 1100 and latch release mechanism 1200 of the CRTe1000. Fig.28 is an isometric view of the variable length axial linkage 1100 and the latch release mechanism 1200 with the latch release mechanism 1200 exploded.

[0284] The variable length axial linkage device 1100 includes a driving cam body 1110, an intermediate cam body 1120, a driven cam body 1130, a latch body 1140, a striker body 1150 and a striker spring 1160. The driving cam body 1110 includes:

[0285] A load adapter 1111 for connecting the CRTe1000 to a top drive casing of a top drive equipped drilling rig (not shown); and

[0286] • A plurality of downward facing trigger reaction pawl notches 1113 .

[0287] The latch release mechanism 1200 has a longitudinal axis X1 that coincides with the longitudinal axis of the CRTe1000, and includes a trigger element 1210, a buffer element 1220, a plurality of trigger followers 1230, a retainer connector 1240, and a trigger spring 1250. The body assembly 1300 includes a body upper shell 1310, a body lower shell 1320, and a body locking sleeve 1330. The clamp assembly 1400 includes a retainer 1410, a plurality of claws 1420, and a plurality of dies 1430.

[0288] The body assembly 1300 is axially carried by the drive cam body 1110. The body upper housing 1310 can be threadedly engaged with the body lower housing 1320, wherein the body locking sleeve 1330 prevents relative rotation between the body upper housing 1310 and the body lower housing 1320.

[0289] Each die 1430 has a gripping surface configured to engage the tubular workpiece 1001. The retainer connector 1240 is rigidly coupled to both the driven cam body 1130 and the retainer 1410. Extension of the variable length axial linkage 1100 will cause the clamping assembly 1400 to move downward relative to the body assembly 1300 and will cause the jaws 1420 and the dies 1430 to move radially inward to engage the tubular workpiece 1001.

[0290] The upper latch assembly 1010 incorporated in the CRTe1000 includes a driving cam body 1110. The lower latch assembly 1020 incorporated in the CRTe1000 includes an intermediate cam body 1120, a driven cam body 1130, a latch body 1140, a striker body 1150, and a striker spring 1160. The variable length axial linkage 1100 has an internal latch that is operable between a latched position and an unlatched position in response to applying a relative rotation and an associated torque between the upper latch assembly 1010 and the lower latch assembly 1020 in a first rotational direction. In the latched position, relative axial separation of the upper latch assembly 1010 and the lower latch assembly 1020 is restrained. In the unlatched position, relative axial separation of the upper latch assembly 1010 and the lower latch assembly 1020 is allowed within a limited range selected as a design choice according to the operational requirements of the CRTe1000.

[0291] Biasing means may be provided (at Fig.261300) to urge the upper latch assembly 1010 and the lower latch assembly 1020 to axially separate, thereby urging the die 1430 to engage the tubular workpiece 1001. However, the biasing device is optional and not required, as in some embodiments, the weight of the clamping assembly may be sufficient to urge the axial separation of the upper latch assembly 1010 and the lower latch assembly 1020. When provided, the optional biasing device can be provided in any functionally effective form in accordance with known techniques (e.g., a coil spring).

[0292] Preferably, but not necessarily, the trigger element 1210, the buffer element 1220 and the retainer connector 1240 are constructed as a coaxial nested set of close-fitting and generally cylindrical components. As used in this context, the term "close-fitting" means that the diametrical clearance between adjacent nested components is selected to allow the components to rotate freely relative to each other while maintaining a substantially coaxial alignment.

[0293] The trigger element 1210 is coupled to the buffer element 1220 so as to be axially movable relative to the buffer element 1220. In the illustrated embodiment, this functionality is provided by trigger splines 1211 on the trigger element 1210 and buffer splines 1221 on the buffer element 1220, but this is provided as a non-limiting example only. In alternative embodiments, this functionality may be provided by any functionally effective means according to known techniques (e.g., a follower element on the trigger element 1210 movable within a vertical slot in the buffer element 1220).

[0294] The trigger spring 1250 acts between the trigger element 1210 and the buffer element 1220 to axially urge the trigger element 1210 toward the drive cam 1110 and thereby bias the trigger pawl 1213 toward engagement with the trigger reaction pawl recess 1113. The trigger spring 1250 urges the buffer element 1220 axially away from the trigger element 1210 and thereby away from the axial linkage 1100.

[0295] The trigger follower 1230 is rigidly mounted to the holder connector 1240. The trigger follower 1230 is also disposed within a corresponding buffer cam slot 1222 in the buffer element 1220 and is movable therein as constrained by the selected configuration of the buffer cam slot 1222. The buffer cam slot 1222 is configured such that when the buffer element 1220 moves axially relative to the holder connector 1240, the buffer element 1220 will also rotate relative to the holder connector 1240.

[0296] The trigger follower 1230 is also disposed within a corresponding trigger recess 1212 in the trigger element 1210, such that the trigger element 1210 is axially and rotationally movable relative to the retainer connector 1240 (and therefore relative to the lower latch assembly 1020, the retainer connector 1240 of which is a component as previously described) within a range of movement defined by the trigger recess 1212. In the illustrated embodiment, the trigger recess 1212 is shown as having an irregular curved configuration, but this is only as a non-limiting example. Embodiments within the scope of the present disclosure are not intended to be limited to or constrained by any particular configuration of the trigger recess 1212, as the configuration of the trigger recess for a particular embodiment will be a matter of design choice. As an illustrative example thereof, the trigger-retainer cam recess 324 shown in FIG. 3 (which is functionally similar to the trigger recess 1212) has a trapezoidal configuration.

[0297] Operation of the Latch Release Mechanism 1200

[0298] The latch release mechanism 1200 is configured such that when the trigger pawl tooth 1213 is disposed within the trigger reaction pawl recess 1113, the axial force applied by the tubular workpiece 1001 to the buffer element 1220 will tend to cause an axial stroke of the buffer element 1220 relative to the lower latch assembly 1020 so as to promote relative rotation between the upper latch assembly 1010 and the lower latch assembly 1020, thereby moving the variable length axial linkage 1100 from a latched position to an unlocked position, wherein the associated torque is transmitted through the trigger element 1210; and such that the application of additional axial force and the resulting axial and rotational displacement of the buffer element 1220 relative to the lower latch assembly 1020 will cause the trigger pawl tooth 1213 to be withdrawn from the trigger reaction pawl recess 1113.

[0299] Fig.29A , 29B , 30A, 30B, 31A, 31B, 32A and 32B show a variable length axial linkage 1100 and a latch release mechanism 1200, wherein the trigger spring 1250 is hidden and the lower portion of the drive cam body 1110 is cut away to expose the trigger pawl 1213 and the trigger reaction pawl recess 1113. More specifically, Fig.29A , 30A , 31A and 32A are cross sections through the variable length axial linkage 1100 and the latch release mechanism 1200, and Fig.29B , 30B , 31B and 32B are front views of the variable length axial linkage 1100 and the latch release mechanism 1200 , wherein the follower cam body 1130 and the retainer extension 1240 are cut away to expose the trigger element 1210 and the buffer element 1220 .

[0300] Fig.29A and 29B The variable length axial linkage 1100 is shown in the latched position. As the CRTe 1000 is lowered onto the tubular workpiece 1001 by the top drive of the drill rig, the tubular workpiece 1001 applies an axial force to the buffer element 1220 which tends to compress the stroke latch release mechanism 1200. Axial movement of the buffer element 1220 relative to the retainer connector 1240 will cause the buffer element 1220 and the trigger element 1210 to rotate relative to the retainer connector 1240 via movement of the trigger follower 1230 within the buffer cam slot 1222. Stroke of the latch release mechanism 1200 will therefore cause relative rotation between the upper latch assembly 1010 and the lower latch assembly 1020, with the associated torque being transmitted to the upper latch assembly 1010 through the trigger element 1210 and to the lower latch assembly 1020 through the retainer connector 1240.

[0301] Fig. 30A and 30B The latch release mechanism 1200 is shown with a stroke sufficient to move the variable length axial linkage 1100 to the unlocked position. Additional axial force exerted on the buffer element 1220 by the tubular workpiece 1001 and continued stroke of the latch release mechanism 1200 will cause further axial and rotational displacement of the buffer element 1220 relative to the retainer connector 1240 and the lower latch assembly 1020. This further axial and rotational displacement will cause the trigger pawl 1213 to withdraw from the trigger reaction pawl recess 1113 through movement of the trigger follower 1230 within the trigger recess 1212 and the buffer cam slot 1222. Fig.31A and 31B The latch release mechanism 1200 is shown fully traveled to retract the trigger pawl 1213 from the trigger reaction pawl notch 1113 .

[0302] The variable length axial linkage 1100 can be re-latched by operating the CRTe1000 to apply a compressive axial load to the variable length axial linkage 1100 and rotating the upper latch assembly 1010 relative to the lower latch assembly 1020 to return the variable length axial linkage 1100 to the latched position. Fig.32A and 32B The variable length axial linkage 1100 is shown returned to the latched position with the trigger pawl 1213 still retracted from the trigger reaction pawl notch 1113 .

[0303] When the variable length axial linkage 1100 is re-latched, the CRTe 1000 does not grip the tubular workpiece 1001. When the CRTe 1000 is lifted off the tubular workpiece 1001 by the drill, the trigger spring 1250 will act between the trigger element 1210 and the buffer element 1220 to push the trigger element 1210 toward the drive cam 1110 and thereby bias the trigger pawl 1213 toward engagement with the trigger reaction pawl notch 1113. At the same time, the trigger buffer spring 1250 will push the buffer element 1220 axially away from the trigger element 1210 and thereby away from the axial linkage 1100. The buffer element 1220 will move axially relative to the retainer connector 1240, and the movement of the trigger follower 1230 within the buffer cam slot 1222 will rotate the buffer element 1220 and the trigger element 1210 to align the trigger pawl 1213 with the trigger reaction pawl notch 1113, thereby resetting the latch release mechanism 1200 to the position in which the latch release mechanism 1200 is re-latched. Fig.29A and Fig.29B The initial state shown in .

[0304] Those skilled in the art will readily appreciate that various alternative embodiments may be devised without departing from the scope of the present teachings, including modifications that may use equivalent structures or materials later conceived or developed.

[0305] It should be specifically understood that the apparatus according to the present disclosure is not intended to be limited to any described or illustrated embodiments, and that substitution of variations of claimed elements or features without any substantial resulting change in the operation of the apparatus and method will not constitute a departure from the scope of the present disclosure.

[0306] In this patent document, any form of the word "comprise" should be understood in its non-limiting sense as meaning to include any elements or features following such words, but not excluding elements or features not specifically mentioned. Reference to an element or feature by the indefinite article "a" does not exclude the possibility of more than one such element or feature, unless the context clearly requires the presence of one and only one such element or feature.

[0307] Any use of any form of the terms "connected," "engaged," "coupled," "latched," "attached," or any other terms to describe the interaction between elements is not meant to limit the interaction to direct interaction between the subject elements, and may also include indirect interaction between elements, such as through secondary or intermediate structures.

[0308] Relational and conformational terms such as (but not limited to) "vertical," "horizontal," "coaxial," "cylindrical," "facing upward," and "facing downward" are not intended to represent or require absolute mathematical or geometric precision. Thus, unless the context clearly requires otherwise, these terms should be understood to represent or require only basic precision (e.g., "substantially vertical"). In particular, it should be understood that any reference herein to an element being "substantially cylindrical" is intended to mean that the element in question may have inner and outer diameters that vary along the length of the element.

[0309] Wherever used in this document, the terms "typical" and "typically" are understood and interpreted merely in the sense of indicating exemplary common usage or practice and should not be understood or interpreted as implying an essentiality or invariance.

[0310] List of components shown

[0311] Component Number Description

[0312] 100 Casing Running Tool (CRT)

[0313] 101 Tubular workpiece

[0314] 102 threaded connection (on tubular workpiece)

[0315] 110 Main body components

[0316] 111 Load Adapter

[0317] 112 tapered thread connection

[0318] 120 Clamping assembly

[0319] 121 Buffer

[0320] 122 Platform Surface

[0321] 123 Claw

[0322] 130 Internal Clamping Casing Running Tool (CRTi)

[0323] 131 Latch release mechanism

[0324] 132 Triple Cam Latch Linkage

[0325] 133 Upper latch assembly

[0326] 134 Lower latch assembly

[0327] 135 Internal Clamping Casing Running Tool (CRTi)

[0328] 136 Latch Release Mechanism

[0329] 140 Clamp-on Casing Running Tool (CRTe)

[0330] 150 Main body components

[0331] 151 Main body upper shell

[0332] 152 Main body lower shell

[0333] 153 Upper housing locking surface

[0334] 154 Axial shoulder

[0335] 160 Floating Load Adapter

[0336] 161 Upper axial shoulder

[0337] 162 Lower axial shoulder

[0338] 163 Load adapter extension

[0339] 164 Lugs

[0340] 165 Skirt

[0341] 170 Clamping assembly

[0342] 171 Buffer

[0343] 172 Platform Surface

[0344] Component Number Description 180 Triple Cam Latch Linkage 181 Upper latch assembly

[0345] 182 Axial shoulder

[0346] 183 Lower latch assembly

[0347] 184 Drive cam

[0348] 185 Drive Cam Latch Hook

[0349] 186 Drive cam housing

[0350] 187 Follower Cam

[0351] 188 Latch Cam

[0352] 189 Latch Cam Latch Hook

[0353] 190 upper cam-housing seal

[0354] 191 Main body - Shell upper seal

[0355] 192 lower cam-housing seal

[0356] 193 body - housing lower seal

[0357] 194 lower cam-retainer seal 195 Upper cam-retainer seal 196 Gas Spring Chamber

[0358] 197CRTe (with latch release mechanism) 198 Latch Release Mechanism

[0359] 201 Latch release mechanism

[0360] 204 Trigger reaction ring

[0361] 205 Trigger reaction claw notch 206 Reaction notch load side 207 Reaction notch top

[0362] 208 Reaction notch locking side 210 Trigger element

[0363] 211 Trigger claw

[0364] 212 Trigger claw load side 213 Trigger claw top

[0365] 214 Trigger claw lock side

[0366] 218 Removable buffer

[0367] 220 Movable platform surface 222 Cage extension

[0368] Component Number Description

[0369] 301 Upper latch assembly

[0370] 302 Upper Rotary Latch Receiver

[0371] 303 Internal upper cam ramp

[0372] 304 Internal lower cam ramp

[0373] 305 Internal Bias Spring

[0374] 310 Lower latch assembly

[0375] 312 Lower Swivel Latch Hook

[0376] 314 Buffer-Trigger Cam Follower 315 buffer-trigger cam groove

[0377] 316 Buffer - Upper end of trigger cam groove 317 Buffer - Lower end of trigger cam groove 318 Buffer-Cage Cam Follower 319 buffer-cage cam groove

[0378] 320 buffer - upper end of the retainer cam groove 321 Buffer - Lower end of the retainer cam groove 322 Trigger-Cage Cam Follower 324 Trigger-Retainer Cam Notch

[0379] 326 Trigger Bias Spring

[0380] 330 Trigger Advance Cam Surface

[0381] 332 Trigger retraction cam surface

[0382] 334 Trigger re-latch cam surface

[0383] 336 Trigger reset cam surface

[0384] 400 Drive cam body

[0385] 401 Drive Cam Latch Hook

[0386] 402 Load Thread 403 drive cam body-housing seal

[0387] 404 drive cam body-spindle seal

[0388] 410 Trigger reaction ring

[0389] 411 Trigger reaction claw notch

[0390] 412 Reaction notch load side

[0391] 413 Reaction notch top

[0392] 414 Reaction notch locking side

[0393] 420 Drive cam housing 421 drive housing-driven housing seal 422 gas spring chamber

[0394] Component Number Description

[0395] 430 intermediate cam body

[0396] 431 Loading Thread

[0397] 440 Trigger Component

[0398] 441 Trigger Claw

[0399] 442 Trigger claw load side

[0400] 443 Trigger claw top

[0401] 444 Trigger claw lock side

[0402] 445 Trigger Cam Slot

[0403] 446 Upper end of the trigger cam groove

[0404] 447 Lower end of trigger cam groove

[0405] 448 Trigger Cam Follower

[0406] 449 Trigger Bias Spring

[0407] 450 Removable buffer

[0408] 451 Movable Platform Surface

[0409] 452 Buffer Cam Follower

[0410] 460 Cage extension

[0411] 461 Buffer-Cage Cam Groove

[0412] 462 Buffer - Upper end of the retainer cam groove 463 Buffer - Lower end of retainer cam groove 464 Cage cam notch

[0413] 466 Advance Cam Surface

[0414] 467 Exit cam surface

[0415] 469 Reset cam surface

[0416] 470 Follower Cam

[0417] 472 drive cam body-cage seal

[0418] 480 Follower Cam Housing

[0419] 490 Latch Cam

[0420] 491 Latch Cam Latch Hook

[0421] 500 Cage

[0422] 501 Cage spindle seal

[0423] 510 Cage extension

[0424] 511 Cage cam groove

[0425] 512 Upper end of the cage cam groove

[0426] 513 Lower end of the cage cam groove 520 Trigger Bias Spring

[0427] Component Number Description 600 main trigger element (alternatively, main trigger) 601 Load Adapter Cam Follower

[0428] 602 Main trigger claw

[0429] 603 Main trigger claw load side

[0430] 604 Main trigger claw top

[0431] 605 Main trigger claw lock side

[0432] 606 Main trigger cam groove

[0433] 607 Upper part of main trigger cam groove

[0434] 608 Lower part of the main trigger cam groove

[0435] 612 claw retract cam groove

[0436] 613 claw retracts to the upper end of the cam groove

[0437] 614 claw retracts to the lower end of the cam groove

[0438] 615 Main trigger reaction surface facing downward 618 Trigger Bias Spring 620 auxiliary trigger element (alternatively, auxiliary trigger) 621 auxiliary trigger cam groove

[0439] 622 Upper end of auxiliary trigger cam groove

[0440] 623 Lower end of auxiliary trigger cam groove

[0441] 624 Auxiliary trigger cam follower

[0442] 625 Auxiliary trigger thread

[0443] 630 Auxiliary trigger extension 631 Seat surface (lower end of auxiliary trigger extension)

[0444] 632 Auxiliary trigger extension thread

[0445] 633 Auxiliary trigger extension lug

[0446] 640 Main body extension

[0447] 641 Second reaction surface

[0448] 642 reaction claw notch

[0449] 643 Reaction notch load side

[0450] 644 Reaction notch top

[0451] 645 Reaction notch locking side 646 claw reaction surface (or first reaction surface) 647 Axially oriented slot

[0452] 648 Body extension load shoulder

[0453] 649 Body Extension Locking Surface

[0454] Component Number Description

[0455] 650 Clamping Ring

[0456] 651 Clamping Ring Load Shoulder

[0457] 660 Body Lock

[0458] 661 Body Lock Lug 1000 Clamp-on Casing Running Tool (CRTe)

[0459] 1001 Tubular workpiece

[0460] 1010 Upper latch assembly

[0461] 1020 Lower latch assembly

[0462] 1030 gas spring 1100 variable length axial linkage 1110 driving cam body

[0463] 1111 Load Adapter

[0464] 1113 Trigger reaction claw notch 1120 intermediate cam body

[0465] 1130 driven cam body

[0466] 1140 latch body

[0467] 1150 Impactor

[0468] 1160 impact spring

[0469] 1200 Latch Release Mechanism

[0470] 1210 trigger element

[0471] 1211 Trigger Spline

[0472] 1212 Trigger Notch

[0473] 1213 Trigger claw

[0474] 1220 buffer element

[0475] 1221 buffer spline

[0476] 1222 buffer cam groove

[0477] 1230 Trigger Follower

[0478] 1240 Cage Connector 1250 Trigger Spring

[0479] Component Number Description

[0480] 1300 Main Components

[0481] 1301 main body hole

[0482] 1310 Main body upper shell

[0483] 1320 main body lower shell

[0484] 1330 Body Locking Sleeve

[0485] 1400 Clamping Assembly

[0486] 1410 cage 1420 jaws

[0487] X1 latch release mechanism 1200 longitudinal axis

Claims

1. A latch release mechanism having a longitudinal axis and acting between an upper latch assembly and a lower latch assembly, the upper latch assembly and the lower latch assembly being coaxially aligned with the latch release mechanism, and wherein: (a) in response to application of relative rotation and associated torque between the upper latch assembly and the lower latch assembly in a first rotational direction, the upper latch assembly and the lower latch assembly are operable between the following positions: a latched position in which relative axial separation of the upper latch assembly and the lower latch assembly is restrained; and an unlocked position in which relative axial movement of the upper latch assembly and the lower latch assembly is permitted within a limited range; (b) the upper latch assembly defines one or more trigger reaction pawl notches; and (c) the upper latch assembly axially carries a generally cylindrical body assembly having a body bore; wherein the latch release mechanism is coaxially disposed within the body bore and comprises: (d) a buffer element coupled to the lower latch assembly such that when the buffer element moves axially relative to the lower latch assembly, the buffer element will also rotate relative to the lower latch assembly; and (e) a trigger element coupled to the buffer element and the lower latch assembly so as to be at least axially movable relative to the buffer element and so as to be axially and rotationally movable within a defined range relative to the lower latch assembly, wherein the trigger element defines one or more trigger pawls configured for axial engagement and disengagement with the one or more trigger reaction pawl notches of the upper latch assembly; Such that when the one or more trigger pawl teeth are disposed within the one or more trigger reaction pawl recesses: Application of an axial force to the buffer element will tend to cause axial travel of the buffer element relative to the lower latch assembly so as to cause relative rotation between the upper latch assembly and the lower latch assembly in a first rotational direction to move the upper latch assembly and the lower latch assembly from a latched position to an unlatched position, wherein an associated torque is transmitted through the trigger element; and • Application of additional axial force and resultant axial and rotational displacement of the buffer element relative to the lower latch assembly will cause one or more trigger pawls to withdraw from one or more trigger reaction pawl notches.

2. The latch release mechanism according to claim 1, wherein: The bumper element and the trigger element are configured as a coaxial nested set of close-fitting generally cylindrical components.

3. A latch release mechanism according to claim 1 or claim 2, wherein: The buffer element is axially movable relative to the trigger element by means of a spline connection.

4. The latch release mechanism according to any one of claims 1-3 further includes a trigger follower, which is connected to the lower latch assembly and is movably disposed in a trigger recess formed in the trigger element, so that the range of axial and rotational movement of the trigger element relative to the lower latch assembly is limited by the construction of the trigger recess.

5. The latch release mechanism according to claim 4, wherein: The trigger follower is also movably disposed within a snubber cam slot formed in the snubber element such that the range of axial and rotational movement of the snubber element relative to the lower latch assembly is defined by the configuration of the snubber cam slot.

6. The latch release mechanism according to any one of claims 1 to 5 further includes a buffer follower, which is connected to the lower latch assembly and is movably disposed in a buffer cam groove formed in the buffer element, so that the range of axial and rotational movement of the buffer element relative to the lower latch assembly is limited by the construction of the buffer cam groove.

7. The latch release mechanism according to claim 5, wherein: The buffer cam groove is configured as an elongated groove having an inclined surface relative to a longitudinal axis of the latch release mechanism.

8. The latch release mechanism according to claim 7, wherein: The inclination of the bumper cam groove relative to the longitudinal axis varies along the length of the bumper cam groove.

9. The latch release mechanism according to any one of claims 1-8, further comprising a trigger biasing device, which pushes the trigger element axially upward toward the upper latch assembly and thereby pushes the one or more trigger pawls toward engagement with the one or more trigger reaction pawl recesses.

10. The latch release mechanism of claim 9, wherein: The trigger biasing device acts between the trigger element and the buffer element to urge the buffer element axially downwardly away from the trigger element.

11. The latch release mechanism of any one of claims 1 to 10, further comprising a bumper biasing means urging the bumper element axially downwardly away from the trigger element.

12. The latch release mechanism according to any one of claims 1 to 11, wherein: The upper latch assembly is coupled to a top drive sleeve of a top drive equipped drilling rig, and the lower latch assembly is coupled to a gripping assembly of a casing running tool coaxially disposed within the body bore.

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