Abstract:
A retention device for maintaining a first rotary machine component axially loaded onto a second rotary machine component in a fixed axial position includes a lock block sized and configured to move between first and second aligned recesses in the first and second rotary machine components. The aligned recesses are shaped to prevent rotation of the lock block, and the lock block has a threaded bore extending therethrough. An actuator is threadably mounted in the bore, such that rotation of the actuator will, in use, move the lock block from the first aligned recess at least partially into the second aligned recess.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to turbine rotors and, more specifically, to a system for the axial retention of a turbine rotor rim seal mounted on a turbine rotor spacer disk. 
         [0002]    Turbine rotor spacer disks are provided with a plurality of rim seals in the form of arcuate seal segments, which, when installed, form a 360° seal. Each seal segment (or, simply, seal or rim seal) is secured to the spacer disk by means of mating dovetail surface features that are configured to enable axial loading of the rim seals onto the spacer disk. Once the rim seals are installed on the spacer disk, there is only limited access to the dovetail area. At the same time, however, the rim seals must be retained axially to prevent slip particularly during engine shipment/operation. Because of the limited access, conventional axial retention schemes cannot be employed. 
         [0003]    There remains a need, therefore, for a simple, low-cost yet effective arrangement for retaining an entire circumferential set of rim seals individually and collectively on a rotor spacer disk so as to prevent undesirable axial shifting of any one or more of the seals. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    In a first exemplary but nonlimiting embodiment, there is provided a retention device for maintaining a first rotary machine component axially loaded onto a second rotary machine component in a fixed axial position, the retention device comprising a block sized and configured to move between first and second aligned recesses in the first and second rotary machine components, the aligned recesses shaped to prevent rotation of the block, the block having a threaded bore extending therethrough; and an actuator threadably mounted in the bore, such that rotation of the actuator will, in use, move the block from the first aligned recess at least partially into the second aligned recess. 
         [0005]    In another aspect, the invention relates to an axial retention system for a plurality of rim seals axially loaded onto a rotor spacer disk, the axial retention system comprising a shear key adapted to be inserted between an annular circumferential groove in the rotor spacer disk and a radial notch formed in a circumferential end face of the rim seal; and a lock block sized and configured to move between first and second recesses formed, respectively, in the rotor spacer disk and said rim seal when the rim seal is loaded axially onto the rotor spacer disk, the lock block provided with an actuator adapted to move the lock block into a position straddling the first and second recesses. 
         [0006]    In still another exemplary but nonlimiting embodiment, the invention relates to an axial retention system for a plurality of rim seals axially loaded onto a rotor spacer disk, the axial retention system comprising for each rim seal except for a finally-installed locker seal, a shear key adapted to be inserted between an annular circumferential groove in the spacer disk and a radial notch formed in an end face of the rim seal; and a back-up stop pin extending from the end face and receivable in a notch formed in an end face of a next-adjacent rim seal. 
         [0007]    The invention will now be described in greater detail in connection with the drawings identified below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a schematic diagram illustrating a rotor spacer disk rim seal in combination with axial movement prevention devices selectively employed with rim seals installed about the spacer disk; 
           [0009]      FIG. 2  is an enlarged detail taken from  FIG. 1 ; 
           [0010]      FIG. 3  is a partial perspective view of the turbine spacer disk with a rim seal installed, utilizing two of the three retention components shown in  FIG. 1 ; 
           [0011]      FIG. 4  is a partial perspective view illustrating in isolation, a stop key notch formed in the end face of the rim seal shown in  FIG. 3 ; 
           [0012]      FIG. 5  is a perspective view of the stop key taken from  FIG. 3 ; 
           [0013]      FIG. 6  is a partial perspective view showing the interaction of a stop pin on one rim seal engaged within a notch formed in an adjacent rim seal; 
           [0014]      FIG. 7  is a partial perspective view illustrating the notch formed in the rim seal that receives the stop pin as shown in  FIG. 6 ; 
           [0015]      FIG. 8  is a partial perspective view illustrating a locker puck recess formed in the spacer disk; 
           [0016]      FIG. 9  is a perspective view illustrating a locker puck partially received within the recess shown in  FIG. 8  but from a different vantage point; 
           [0017]      FIG. 10  is a section view showing the locker puck of  FIG. 9  in combination with a rim seal installed on the spacer disk; 
           [0018]      FIG. 11  is a partial perspective view illustrating the locker puck located between the rim seal and the spacer disk; 
           [0019]      FIG. 12  illustrates a bolt actuator in accordance with another exemplary embodiment; 
           [0020]      FIG. 13  illustrates the bolt of  FIG. 12  with a locker puck attached; and 
           [0021]      FIG. 14  illustrates an axial movement prevention device employed with rim seals installed about the spacer disk in accordance with an alternative exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    In the exemplary but nonlimiting embodiment, the axial retention system for the rotor spacer disk rim seals is made up of three components. As will be explained in further detail below, not all of the components are used with every rim seal. In this regard, it will be appreciated that the rim seals are loaded axially onto the spacer disk. The assembly is done in a sequential manner, and the system as disclosed herein utilizes at least two of the components for all but the finally-installed rim seal. A third component is employed with the finally-installed seal (also referred to as the “locker seal”) to effectively lock the entire array of seals to the spacer disk. 
         [0023]    Thus with reference initially to  FIGS. 1 and 2 , a rim seal  10  is shown, in schematic form, axially loaded onto the rotor spacer disk  12 . The rim seal  10  interfaces with adjacent turbine components  14 ,  16 , as is well understood in the art. As illustrated, the loading or installation direction is from right-to-left. The three axial retention components in accordance with the exemplary but nonlimiting embodiment, include a shear key  18 , a back-up pin  20  and a locker “puck” (also referred to herein as a lock block)  22 .  FIGS. 1 and 2  are intended to show the components utilized during installation for convenience and ease of understanding but, for all but one of the rim seals  10  loaded onto the spacer disk  12 , only the shear key  18  and back-up pin  20  are utilized. The last rim seal or locker seal  10  installed on the spacer disk utilizes the locker puck  22 , but not the shear key  18  or back-up pin  20 , as further explained below. 
         [0024]    With reference now also to  FIGS. 3 and 4 , one circumferential end face  24  of the rim seal  10  is formed with a radially-oriented notch  26  adjacent the entry end of the spacer disk slot  27 , opening from the bottom surface  28  of a flange portion  30  of the rim seal as well as from the end face  24 . The notch  26  is otherwise closed in circumferential and axial directions. The notch  26  is located to align radially with a discontinuous annular groove  34  formed in the spacer disk  12  upon installation of the rim seal  10  (sometimes referred to herein simply as “the seal  10 ”). It will be appreciated that the groove  34  and notch  26  may be located further away from the entry end of the disk slot  27  if desired. 
         [0025]    The L-shaped shear key  18  (see also  FIG. 5 ) is located in the groove  34  and notch  26  as best seen in  FIG. 3 . The dimensions and shape of the shear key  18  are such that it can be located in only one orientation, making installation fool-proof. More specifically, the radially outwardly extending leg or stem  36  of the L-shaped shear key is formed with an angled corner  38  that mates with a correspondingly-shaped angled corner  40  of the notch  26 . The horizontal (or circumferential) leg or base  42  of the L-shaped shear key  18  sits in the groove  34 . It will be appreciated that the shear key  18  can be located in the groove  34  and notch  26  after the seal  10  is axially loaded onto the spacer disk  12  or, alternatively, the shear key  18  can be located in the groove  34 , laterally away from the seal  10  and moved into engagement with the notch  26  after the seal  10  is installed. 
         [0026]    Note also the aperture  44  formed in the base  42  of the shear key  18 . This allows easy removal of the shear key with the use of a suitable tool (not shown). It is not necessary, however, to secure or fix the shear key  18  within the notch  26  and/or groove  34 . Since the next adjacent rim seal abuts the rim seal  10  and overlies the base  42  of the key  18 , further movement of the shear key is precluded. The shear key  18  thus prevents movement of the rim seal  10  in either axial direction, and the shear key is itself locked into place by the next adjacent seal. 
         [0027]    The circumferential end face  24  of the seal  10  is also formed with a blind bore  46  ( FIG. 6 ) at the opposite end of the face  24  from the shear key  18 . The bore  46  receives the back-up stop pin  20  (cylindrical in the example embodiment) via a press fit, or by other suitable means, leaving a portion of the pin  20  exposed. Like the shear key  18 , the stop pin  20  prevents axial movement of the rim seal  10  in at least one axial direction, as described further below, thus providing a back-up function in the event that the shear key  18  has been inadvertently omitted during installation of the seal. 
         [0028]    With reference specifically to  FIGS. 3 and 6 , it will be appreciated that the next adjacent seal can be slid axially along its dovetail groove  48  formed in the spacer disk, passing by (and over) the base  42  of the shear key  18  and stopping when the axial stop pin  20  engages within an open notch  50  ( FIGS. 6 ,  7 ) formed in the circumferential end face  52  of a next adjacent seal  54 . The notch wall  56  thus serves as the stop limit for the axial installation movement in one direction of the next adjacent seal, and the next-installed shear key then also precludes any axial movement in both the installation and opposite directions. 
         [0029]    Now with reference to  FIGS. 8-11  in order to lock the final seal  58  in place, the third retention component is utilized. An oblong or oval locker “puck”  22  is shaped and sized to fit in and between vertically-adjacent, recesses  60 ,  62  formed in the spacer disk  12  and seal  58 , respectively. More specifically, the oblong or oval recess  60  is formed in the upper (radially outer) surface  64  of the spacer disk post  66  ( FIG. 8 ). The recess  62  ( FIGS. 10-11 ) is formed in the radially inner surface  68  of the seal flange portion  70 , the recesses  60  and  62  vertically (or radially) aligning when the seal  58  is loaded into the spacer disk  12 . 
         [0030]    A threaded bore  72  extends vertically or radially through the puck  22  and a threaded adjustment stud or screw  74  extends through the puck  22 . A bore  76  may be formed in the seal and extends radially outwardly to an access location, where a tool may be inserted. The tool is designed to engage a surface feature  78  (e.g., an Allen-wrench recess) formed in the end of the stud or screw  74 . When the stud  74  is rotated by the tool, the puck  22  moves along the stud because the puck is held in a non-round recess. Thus, rotation of the stud  74  in a clockwise direction causes the puck  22  to move radially outward to the position shown in  FIGS. 9-11 , where the puck is partially-engaged in both recesses  60 ,  62 . The locker puck  22  thus locks the final seal  58  in place and, in so doing, in combination with the shear keys and back-up pins, locks all of the rim seals against any axial movement within the spacer disk  12 . Note in this regard that if all of the shear keys were omitted, all of the seals except the finally-installed seal would be locked in one axial direction only, because the back-up pins prevent axial movement in only one direction. 
         [0031]    Note also that for the final rim seal  58 , neither shear key  18  nor the back up pin  20  are used. 
         [0032]    Alternatively, an elongated bolt  80  ( FIGS. 12 ,  13 ) with a threaded end  82  may be used to engage the puck  22 . The bolt  80  will extend through the bore  76  and rotation of the bolt will cause the puck  22  to move axially along the threaded end  82  (and radially relative to the spacer disk) substantially as described above. A fail or weak point in the form of groove  84  may be provided in the bolt shank  86  adjacent the threaded end  82  to facilitate breaking and removal of the bolt shank after installation if desired. 
         [0033]    In another alternative arrangement, a frangible shim  88  is integrally attached to the lower part of the threaded shank  74  as shown in  FIG. 14 , in conjunction with an extended receptacle portion  90  provided in the disk, radially inward of the recess  60 . This allows the shank  74  to be punched radially into the receptacle portion  90 , causing the puck  22  to fall back into the rotor disk, thus providing an alternative technique for releasing the rim seal for axial movement. 
         [0034]    With the above-described arrangement, all components, i.e., the shear key  36 , locker puck  22  and stop pin  20  are enclosed within the rim seal/spacer disk so that in the event of failure, the components are substantially precluded from dropping into the internal wheel space of the rotor. 
         [0035]    It will also be appreciated that the locker puck  22  may be utilized in the three-component system as described above, or, alternatively, as a stand-alone retention device used in connection with any one or all of the rim seals. Moreover, the locker puck  22  can be employed in any other application where retention of one component in a slot formed in a second component is desired. 
         [0036]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.