Patent Publication Number: US-10760363-B2

Title: Lock ring segments biased into locked position while retained in position with an exterior profile

Description:
FIELD OF THE INVENTION 
     The field of the invention is ratcheting lock ring segments that have exterior profiles to allow the segments to move radially while retaining the segments axially as a bias force is applied at ends or in between ends within the exterior profile. 
     BACKGROUND OF THE INVENTION 
     Many borehole tools need to lock to hold their set position. This has been accomplished in the past with body lock rings that are typically a single piece with a split for ease of assembly and for retention of a net potential energy force, typically toward an internal mandrel that has one part of a mating ratchet profile. The lock ring has a mating part of the ratchet profile so that relative movement with respect to a mandrel of an outer assembly that has the lock ring will bring the ratchet pattern on the lock ring into contact with the ratchet pattern on the mandrel. Because of the shape of the opposed profiles that come into contact during setting movement, relative movement of an outer assembly around the mandrel and the mandrel itself is permitted until the tool sets. Relative movement in an opposite direction is prevented by the shape of the mating ratchet profiles. 
     The ratchet ring can be a 360 degree complete ring with axially extending spaced segments as described in US 20170167217. Other examples of traditional locking rings can be seen in U.S. Pat. Nos. 7,448,591; 6,209,653 and 7,222,889. 
     Using biased lock ring segments in close end spacing is illustrated in US 20160168945 in FIG. 8. The segments are spring biased from recesses in an exterior elongated lug that retains the segments axially in a recess in a surrounding housing. The biasing springs abut the recess and push the lug toward a mating pattern on an internal mandrel. This reference allows for the segments to be pushed out from within mandrel openings so as to release the set position of a tool for retrieval. 
     U.S. application Ser. No. 15/259,246 reveals the use of spaced lock ring segments with sufficient circumferential gaps to accept bars that transfer force past lock rings to a settable component below in a situation where another tool component has been set earlier without a substantial drift reduction of a passage through the tool. 
     What is needed and offered by the present invention is a retention feature on the outer surface of the locking segments that allows them to be radially biased into an opposed ratchet profile so that relative movement in a first direction is enabled by ratcheting as the segment jumps an opposing profile mounted to a mandrel, for example. The segments can be supported on a mandrel or on an opposing housing and still operate in the same manner. Relative movement in the opposite direction is prevented by each segment as each such segment is retained against axial movement by an outer profile that can be a spiral pattern, undulating parallel ridges or other patterns that are either discrete or continuous as will be explained below. A bias can be applied at one or both axial ends of each segment or in between ends. The biasing can be realized by coiled or wave springs located between the outer face of the segments and the mating retention profile in a surrounding outer housing. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the detailed description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims. 
     SUMMARY OF THE INVENTION 
     Ratchet locking segments permit one direction relative movement, either initially partially or for the full range of allowed relative movement in that direction, and then prevent reverse movement to hold a set position of a tool. The segments are axially supported in a surrounding housing using an exterior profile on each segment meshing with a conforming profile on the outer housing. The meshing is loose to allow the segments the ability to move radially while supported axially. Biasing of opposed ratcheting segments toward each other is provided by a spring or springs at opposed axial ends of each segment or within the exterior profile between the axial ends. The end biasing can be done with coiled springs or bent tabs that store potential energy when assembled or with wave springs between the segment outer profile and a surrounding outer housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of six segments for locking to show the internal and external patterns on each segment; 
         FIG. 2  is an axial section view through a mandrel and an outer housing showing a locking segment in between; 
         FIG. 3  is a close up detail of  FIG. 2  showing a radial inward bias from an axial end of a locking segment and the set and locked position; 
         FIG. 4  is the view of  FIG. 3  during ratcheting relative movement to the set position; 
         FIG. 5  is a perspective view of a lock ring segment showing end tabs that can store a potential energy force for the locking segment against an internal ratchet profile on a mandrel; and 
         FIG. 6  shows biasing of the lock ring segment between ends with a wave spring. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1  a perspective view of locking segments  10  shows that each of the illustrated six segments  10  have an interior profile for ratcheting in relative movement in one direction and locking against opposed relative movement. The exterior profile  14  serves to axially retain each segment  10  while allowing the segment  10  to move radially inwardly under a bias force or outwardly when overcoming the bias force during ratcheting while being supported axially as will be explained below. While six segments are shown, those skilled in the art will appreciate that other quantities could be used without departing from the invention. The segments can be formed from a ring that is cut into one or more pieces and mounted with circumferential spacing or a gap in the case of a single piece or the segments can be discrete structures, with or without curvature as long as facing mating profiles can engage to allow relative movement in one direction and prevent such relative movement in an opposed direction. While large gaps are shown in  FIG. 1  between the segments  10  the segments can be closely spaced or the gaps can be wide enough to allow other relatively moving members to pass in between to operate portions of a borehole tool. 
       FIG. 2  is a section through a segment  10  that shows a mandrel  16  within an outer assembly  18 . Mandrel  16  has one portion  20  of a ratchet pair while the facing portion  12  is on each locking segment  10  comprises the other part of the ratchet pair. Mandrel  16  or housing  18  is movable in the direction of arrow  22  relative to the outer assembly  18  as ratchet profile ramps  12   a  are pushed up radially away from mandrel  16  on ramps  20   a  of moving mandrel  16  for the set position. The segments  10  can move out radially because outer profile  14  has room for axial and radial movement in mating profile  26  as shown in  FIG. 3 . Opposed mandrel movement in the direction of arrow  24  is prevented as radial surfaces  20   b  on mandrel profile  20  abut radial surfaces  12   b  on the lock ring segment  10 . At the time the position of  FIG. 3  is attained the outer assembly  18  interacts with the borehole wall or surrounding tubular for a set position. Some examples of devices that can be part of the outer assembly  18  can be anchor slips or a seal assembly that are not shown. In this manner relative movement of the mandrel  16  in the direction of arrow  22  causes repeated radial movements of segments  10  away from mandrel  16  as the ratcheting movement takes place. Each time the segments  10  move out radially a bias on each segment that can be a spring  28  that is preferably a coiled spring and is preferably located on at least one side but preferably opposed sides of mating profile  26  is overcome as each segment  10  moves radially away from mandrel  16 , or the housing  18  depending on the configuration, that is translating in the direction of arrow  22 . Spring  28  can be guided internally of its coil, if it is a coiled spring, and otherwise guided externally within profile  26  or elsewhere along a segment  10  or by outer assembly  18 . Alternatively, spring  28  can be within the profile  26 . Spring  28  has the purpose of applying a biasing force on its associated locking segment  10  toward mandrel  16  while allowing each associated locking segment  10  the ability to move radially away from mandrel  16  to enable the ratcheting movement of mandrel  16  in the direction of arrow  22 . Arrow  30  illustrates the spring force on the locking segment  10  toward mandrel  16 . That force represented by arrow  30  is overcome several times as the ratcheting takes place with mandrel  16  moving in the direction of arrow  22 . That force toward mandrel  16  is overcome during ratcheting as the segments  10  are pushed away from mandrel  16  as indicated schematically by arrow  32 . 
     The engagement of outer profile  14  into outer assembly  18  and inner profile  26  serves to retain the segments  10  in an axial direction while providing the freedom of segments  10  to move radially toward mandrel  16  under the influence of spring or springs  28  and to move radially away from mandrel  16  due to the ratcheting movement between ramps  20   a  pushing on facing ramps  12   a  as mandrel  16  moves in the direction of arrow  22 . Profiles  14  and  26  have conforming shapes with profile  26  being slightly larger axially and radially so that conforming profile  14  can move radially into profile  26  without bottoming out and to leave an axial clearance between the two to facilitate the radial movement of segments  10  into and out of profile  26 . Profiles  14  and  26  can comprise a continuous spiral, a series of parallel peaks and valley that can be trapezoidal in shape as shown in  FIG. 4  or rounded or rectangular shaped. Triangular, quadrilateral or rounded shapes can be used as well as other mating shapes. An undulating sinusoidal shape in section can also serve as profiles  14  and  26 . The common theme in the engaged profiles  14  and  26  is that the segments  10  are axially supported between the mandrel  16  and the outer assembly  18  while permitting clearance within the mating profiles  14  and  26  to allow the segments  10  freedom to be biased toward the mandrel  16  by spring  28  and to be pushed radially away from mandrel  16  by the ratcheting action as mandrel  16  moves in the direction of arrow  22 . 
       FIG. 5  illustrates an alternative to end springs  28  in the use of axially extending tabs  34  and  36  that have raised end segments  38  and  40  respectively. When the outer assembly  18  is mounted over mandrel  16  the portions  34  and  36  push the segment  10  toward the mandrel  16  but the ratcheting action allows axially oriented tabs  34  and  36  to flex radially to enable the radial movement of segments  10  needed for effective ratcheting action. A fastener can be placed into openings from the outer housing  18  to maintain support axially for the segments  10  during the ratcheting caused by moving mandrel  16  in the direction of arrow  22 . Tabs  34  and  36  can be guided by the fastener that fits through openings  42  so that radial flexing of segments  10  is enabled at a time when the segments  10  are radially supported. Alternatively the segments  10  can be guided on their opposed edges in a way that enables the needed radial movement. 
       FIG. 6  shows the use of one or more wave springs  44  to bias the segments  10  toward mandrel  16 . In this example the bias is within the meshing profiles  14  and  26  rather than at opposed ends as in  FIGS. 3 and 4  where springs  28  straddle the ends of the engaged profiles  14  and  26 . The wave springs  44  can discrete segments or a continuous spiral shape depending on the shape of the profiles  14  and  26 . As an alternate to metallic wave springs segments or a continuous piece of a resilient material such as rubber or another material compatible with well conditions can be used to provide the spring bias toward the mandrel  16 . Belleville washers are another possible alternative for bias of the segments  10  toward the mandrel  16 . In  FIG. 6  the springs  44  are shown in the valleys of profile  14  but they can also be disposed on the peaks instead or in the peaks and the valleys. 
     Those skilled in the art will appreciate that the segmented locking members can be radially biased toward the mandrel with spring force at one or opposed ends of an exterior profile or from within the exterior profile with wave springs or with a resilient material. The use of an exterior profile that engages a mating profile in an outer housing provides axial support for the locking segments while allowing freedom of radial movement in opposed directions toward and away from the mandrel. The use of multiple support surfaces in the outer locking segment profile and the surrounding outer housing distributes axial locking load so as to reduce stress on each bearing surface or on a continuous or segmented spirally oriented surface. In section these mating profiles can feature a series of parallel ridges, a sinusoidal shape, rectangular or square or trapezoidal profile shapes whether the profile is a continuous thread or spiral or a segmented thread or spiral or is simply a series of parallel discrete profiles regardless of orientation perpendicular or skewed with respect to the mandrel axis. Flexing end tabs that are axially oriented can bias the locking segments toward a mandrel and allow opposed radial movement during ratcheting by flexing away from the mandrel, as illustrated in  FIG. 7 . While the locking segments are shown with a plurality of protruding shapes or a continuous or segmented protruding spiral shape, the pattern can be reversed with the locking segments having the female portion of the mating profile with the outer assembly having the male portion. 
     The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: