Patent Publication Number: US-2022235620-A1

Title: Release Mechanism for a Jarring Tool

Description:
This application is a continuation of U.S. patent application Ser. No. 16/250,836 filed Jan. 17, 2019, the entire contents of which are incorporated herein by reference thereto. 
    
    
     BACKGROUND OF INVENTION 
     1. Field of the Invention 
     This invention is directed to a release mechanism for a mandrel of a jarring device commonly referred to as a jar and is related to application Ser. No. 16/168,610 filed Oct. 23, 2018, the entire contents of which is incorporated herein by reference thereto. Jars are used in the well drilling industry to free downhole tools that may become lodged in a well. An upward or downward force can be supplied to a tubular string which includes the affected tool in order to break free the tool from the well bore. 
     2. Description of Related Art 
     Typically, a release mechanism in the form of an annular collet is provided which normally prevents axial movement of the mandrel. The mandrel is spring biased to move with significant force in an upward or downward direction. If a sufficient force is placed on the mandrel, the collet will release. 
     U.S. Pat. No. 5,022,473 discloses a release assembly which comprises a plurality of angular segments 62 and 162 that engage in slots 86 and 88, and 186 and 188 respectively. It has been found that this arrangement can result in the segments 62 and 162 becoming out of alignment which could result in the failure of the release mechanism. As disclosed in the patent, the jar requires two sets of release lugs to withstand the anticipated tensile load. In this design the two lug assemblies must be spaced further apart than the total travel of the jar to prevent the lower lug from inadvertently engaging the groove of the upper lug assembly. If a third lug assembly were necessary it would have to be spaced a distance greater than the jar stroke from the lower set. This would significantly increase the total length of the jar and also the cost. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention solves the above noted problem by providing a plurality of angular lug segments each of which has two or more projections that engage corresponding grooves in the mandrel. The segments may be positioned within cutouts of an annular support collar or may include projections that are adapted to be received in recesses of adjoining lug segments to stabilize the segments. 
     In order to avoid misalignment or a jarring situation, the projections have either a differing width or are spaced at different distances. The grooves on the mandrel have a complimentary configuration as will be explained below. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG. 1  is a perspective view of a first embodiment of a release lug. 
         FIG. 2  is a perspective view of an annular support collar. 
         FIG. 3  is a cross-sectional and perspective view of the release mechanism. 
         FIG. 4  is a cross-sectional view of the release in mechanism in a non-release position. 
         FIG. 5  is a perspective view of a release lug according to a second embodiment of the invention. 
         FIG. 6  is a perspective view of a release mechanism according to a second embodiment of the invention. 
         FIG. 7  is a cross-sectional view of the second embodiment of the release mechanism shown in a non-release position. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a single release lug  20 . It includes a plurality of grooves  27  and  24  in its outer surface that are adapted to receive a plurality of springs  54  as shown in  FIG. 3 . The springs may be garter springs as shown or annular leaf springs. 
     Each lug  20  also includes a plurality of grooves  22  on their outer surface which form a plurality of ridges  21 . The inner surface of each leg includes a plurality of grooves  32  which in turn form a plurality of ridges  31  and  33 . The inner surface also includes two arcuate surfaces  58  and  59 . 
     As shown in  FIG. 2  an annular support collar  40  includes one or more cutout sections  44  that are adapted to receive lugs  20 . Support collar  40  also includes a plurality of grooves  42 ,  43 ,  46 , and  47  that are adapted to receive stabilizing springs  54 . 
       FIG. 3  shows the lugs  20  positioned within cutouts  44  with springs  54  positioned within the grooves provided on the outer surface of lugs  20  and support collar  40 . Also shown in  FIG. 3  is a trigger sleeve  50  which includes an annular lip  53 , a first surface  55  and a thick portion  51  on the outer surface. 
       FIG. 4  illustrates the release mechanism in an assembled position. The mandrel of the jarring device, not shown, would be located within the release mechanism as is known in the art. The outer surface of the mandrel would include a plurality of ridges and grooves as shown at  31  and  32  in the above mentioned patent application. 
     The interior surface of trigger sleeve  50  includes a plurality of grooves  56  and  57  forming a plurality of ridges  52 . In the position of  FIG. 4  the mandrel would be in the non-release position. As support collar  40  and lugs  20  are axially moved to the left as shown in  FIG. 4 , ridge  21  on the outer surface of lug  20  will be free to engage into grooves  57  of the release trigger  50 . Release lugs  20  will move radially outward which will disengage the release lugs  20  from the mandrel. This in turn will allow the mandrel to cause the jarring force as is known in the art. 
       FIGS. 5-7  illustrates a second embodiment of the invention. In this embodiment, each lug  60  is similar to the lug shown in  FIG. 1  but each lug includes a pair of posts  68 ,  69 , one at each end, and a pair of cavities  64 ,  67  one at each end of the lug. Cavities  64 ,  67  are adapted to receive the posts  68 ,  69  of an adjacent lug as shown in  FIG. 6 . Each lug includes a plurality of ridges  61  and grooves  91  on its exterior surface and a plurality of ridges  92  and grooves  93  on its interior surface. 
     Grooves  62 ,  63 ,  65 , and  66  are located on the exterior surface of each lug for receiving annular springs  75 ,  76  which may be a garter or leaf spring. 
     As shown in  FIG. 6 , the release mechanism  70  includes a plurality of lugs  60  that are positioned to form an annular array. Each lug is initially spaced apart from an adjacent lug by a distance  79 . Posts  68 ,  69  are located within cavities  64 ,  67  of an adjacent lug. As a result, the assembly of lugs can expand and contract in a radial direction depending upon the longitudinal relationship between the lugs and the trigger sleeve  70 . 
     Trigger sleeve  70  includes a plurality of ridges  71  that form grooves which allow lugs  60  to expand radially outward when ridges  71  of the trigger sleeve align with grooves  91  of the lugs. 
     Trigger sleeve  70  includes an annular lip  73 , an annular section  72  and a raised annular section  74 . 
     In order to operate the jarring device a load is put on the mandrel, not shown, to the left as shown in  FIG. 7 . The mandrel which includes ridges and grooves will carry the release lugs to the left while the trigger sleeve remains stationary. As grooves  91  in the lugs align with ridges  71  in the trigger sleeve, the release assembly will expand radially outwardly allowing the mandrel to be released. During the expansion the dimension of posts  68 ,  69  and cavities  67 ,  64  are selected so that the posts  68  and  69  are located within the cavities during the entire release and reset positions. 
     Although the present invention had been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.