Abstract:
A wheel disk assembly, having a wheel disk, a plurality of blade devices, which are fastened along the outer circumference of the wheel disk, and a plurality of sealing plates, which are retained in two annular grooves radially spaced apart from each other. A first annular groove is in the wheel disk and a second annular groove is formed by the blade devices in a segmented manner. Simplified mounting of the sealing plates is achieved in that the first annular groove is expanded by an axially extending recess.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the US National Stage of International Application No. PCT/EP2016/050343 filed Jan. 11, 2016, and claims the benefit thereof. The International Application claims the benefit of European Application No. EP15156321 filed Feb. 24, 2015. All of the applications are incorporated by reference herein in their entirety. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates to a wheel disk assembly having a wheel disk and a plurality of blade devices fastened on the wheel disk and a plurality of sealing plates fixed in an annular slot on the wheel disk. 
       BACKGROUND OF INVENTION 
       [0003]    Wheel disk assemblies of the type referred to in the introduction are known in the prior art in a very wide variety of embodiments, wherein in a conventional embodiment a wheel disk has on the outer circumference a plurality of blade-root-locating slots which extend in the direction of the disk axis. Blade devices are arranged in these by their blade root. For the end-face covering of the blade-root-locating slots, sealing plates are inserted and for this purpose are generally mounted in annular slots. GB 905,582 A discloses a typical example of this. In this case, the wheel disk has an encompassing, outwardly open, inner annular slot in which is axially fixed an end of the sealing plate which points toward the disk axis. On the opposite outer end of the sealing plate provision is made for an inwardly open outer annular slot. The outer annular slot is formed by the blade devices which are adjacent to each other in the circumferential direction. 
         [0004]    During installation, the blade devices are inserted into the blade-root-locating slots of the wheel disk, wherein the sealing plates are also inserted in succession between the two annular slots. In order to be able to install the last two blade devices, all the sealing plates have to be already mounted beforehand and be displaced in the annular slots via their overlapping regions by such a distance that the blade devices can be installed in the associated slots of the wheel disk. The sealing plates are then pushed back again in the circumferential direction into their designated position and suitably secured there against a displacement in the circumferential direction. 
         [0005]    A disadvantage of the known wheel disk assemblies exists in the fact that the sealing plates in the event of a service can only be removed with difficulty since two adjacent blade devices have first of all to be removed which in practice is accompanied by a considerable cost. 
       SUMMARY OF INVENTION 
       [0006]    Starting from this prior art, it is an object of the present invention to create a wheel disk assembly of the type referred to in the introduction, in which a greater degree of flexibility is achieved with regard to the mounting of the sealing plates. 
         [0007]    The generic wheel disk assembly comprises a wheel disk, a plurality of blade devices and a plurality of sealing plates. The wheel disk has in this case a blade-locating section which is arranged on the outer circumference. Fastened on this, in a detachable and circumferentially distributed manner, are the blade devices. Furthermore, the wheel disk has an annular projection which is at an axial distance from the blade-locating section. An annular slot is arranged between the blade-locating section and the annular projection. The sealing plates, by an edge region pointing toward the disk axis, are mounted in the annular slot and fixed in the axial direction by means of the blade-locating section and the annular projection. The disk axis obviously corresponds to the central rotational axis of the rotor disk. The edge region of the sealing plates is adjacent to the end of the sealing plates which points toward the disk axis and extends radially vertically corresponding to its arrangement in the annular slot. 
         [0008]    For achieving the object, it is provided according to the invention that the annular slot is widened in the axial direction by at least one recess which defines a sealing-plate-mounting region. In this respect, the recess extends from the annular slot in the axial direction into the blade-locating section and/or into the annular projection. In this case, it is necessary that the length of the recess in the circumferential direction is greater than the length of the sealing plates in the edge region. 
         [0009]    Thanks to such a recess, the sealing plates can be threaded in a simple manner into the associated annular slots, even if all the blade devices are already mounted on the wheel disk, as a result of which the mounting is designed in a very flexible manner. In this case, the sealing plates can be inserted by the edge region for example at an angle from above into the recess and the sealing plate can then be tilted in the direction of the wheel disk. After that, the sealing plate can be moved in the circumferential direction along the annular slot. By the same token, the individual sealing plates can be removed again in a simple manner in the reverse sequence. 
         [0010]    It is basically irrelevant in the first instance whether the annular slot is of segmented and/or discontinuous design provided that the discontinued regions are not required for attaching a sealing plate. In both a simpler and particularly more advantageous embodiment, the annular slot in cross section—apart from the recess—is of constantly encompassing design. 
         [0011]    According to one embodiment of the present invention, all the sealing plates are identically designed as identical parts, as a result of which the production and also the storage of the sealing plates are simplified. 
         [0012]    It is particularly advantageous if the recess also extends in the radial direction pointing toward the disk axis. That is to say that the recess over a limited length enlarges the cross section of the annular slot in the axial direction and in the radial direction. 
         [0013]    As a result of the enlargement which is provided both in the axial direction and in the radial direction by means of the recess, an advantageous free space is created for mounting the sealing plates by their edge region. In particular, it is possible to first of all insert the sealing plates into the recess in such a way that these are positioned closer to the disk axis than in line with the end position. The sealing plates can subsequently be outwardly displaced in the radial direction and therefore be relocated into the end position. 
         [0014]    The annular projection, on the side facing the annular slot, advantageously has a bevel in the region of the recess, wherein the bevel is designed so that the annular projection is flattened toward the annular slot. Such a bevel also simplifies the insertion and removal of the sealing plates in the region of the recess. 
         [0015]    According to one embodiment of the present invention, the annular projection, on the side facing the annular slot, has in the region of the recess an undercut region in the form of a cavity which is open toward the annular slot. 
         [0016]    Provision is advantageously made for two recesses which are formed diametrically opposite one another in the wheel disk. Thanks to a second recess, imbalances can be avoided during the designated installation of the wheel disk assembly. Furthermore, the sealing plates can be mounted and removed more quickly. Also conceivable is the arrangement of a multiplicity of recesses which are to be distributed over the circumference rotationally symmetrically to the disk axis. 
         [0017]    According to one embodiment of the present invention, the annular slot is of undercut design and, as seen in cross section, has at least one retaining projection which projects axially in the direction of the sealing plate. The retaining projection is correspondingly selectively located on the blade-locating section and/or on the annular projection and is arranged radially outside the annular slot. In this case, the retaining projection has a retaining surface on the side pointing toward the annular slot, i.e. toward the disk axis. It is irrelevant in the first instance whether retaining projections are provided on one side or on both sides and whether one retaining surface or a plurality of retaining surfaces are provided on the retaining projection. The embodiment with a retaining projection extending circumferentially along the annular slot, with a retaining surface arranged thereon, is both adequately and advantageously simple. Corresponding to this, the sealing plates in the edge region have at least one axially projecting support projection which is provided with a support surface. Therefore, the edge region with the support projection acts as a thickening for the region of the sealing plate which lies radially outside the edge region. 
         [0018]    The retaining surface of the retaining projection and the support surface of the support projection are arranged in such a way that the support surfaces of the sealing plates, during the designated operation of the wheel disk assembly, are supported against the retaining surface of the retaining projection under the influence of a centrifugal force. Thanks to this embodiment, the natural weight of the sealing plates under the influence of a centrifugal force is absorbed by the wheel disk, as a result of which the blade devices are relieved of load. 
         [0019]    Provision is made for at least one filler piece which is arranged in the recess. By means of the filler piece, it is possible to prevent an inadvertent slipping out of the sealing plate from the annular slot or a partial deformation of the sealing plate in a position in which the sealing plate is arranged over a part of the length in the region of the recess. To this end, it is necessary that the filler piece butts against the sealing plate. 
         [0020]    In this case, it is advantageous on the one hand if the filler piece by a radially extending contact surface butts axially against the edge region of the sealing plate. Therefore, the axial fixing of the sealing plate is also ensured in the region of the recess. 
         [0021]    Furthermore, it is advantageous if the filler piece has an axially extending contact surface pointing radially outward, against which an inner circumference of the sealing plate butts. Correspondingly, the sealing plate in the region of the recess can be supported on the filler piece and, especially in the case of a recess which extends radially into the wheel disk, is not displaced toward the disk axis with the disk assembly stationary for example. 
         [0022]    The filler piece is advantageously designed in such a way that a bevel provided on the annular projection is filled out. As a result of this, on the one hand, imbalances as a result of material gaps which otherwise exist on one side are prevented, and in particular a better support of the filler piece is provided by the sealing plate in the event of an axial load. 
         [0023]    Furthermore, it is advantageous if the filler piece, with provision of a cavity which opens toward the recess, projects into this cavity. On account of the undercut design in this region as a result of the cavity, the radial fixing of the filler piece can be achieved. 
         [0024]    In a particularly advantageous embodiment, the blade devices have in each case an annular slot segment which extends in sections around the disk axis and is open radially toward the disk axis. In this case, it is provided that the sealing plates are accommodated on their outer circumference in the annular slot segments and in this case are fixed in the axial direction. In this case, it is irrelevant whether provision is made on the sealing plate for further contours which are arranged axially next to the outer circumference considered here. Essential instead is a securing of the position of the sealing plate on the outer circumference in the direction of the disk axis. 
         [0025]    Taking into consideration the advantageous recess which extends radially into the wheel disk, this leads to a mounting in which the sealing plate is first of all lowered into the recess and after pivoting or pushing is moved radially outward onto the wheel disk. With this, the insertion of the sealing plate by the outer circumference into the annular segments is then carried out. In this case, it is irrelevant whether a sealing plate is accommodated in each case in an annular slot segment or whether the sealing plates are advantageously arranged in an overlapping manner in relation to the blade devices and in this respect engage in adjacent annular slot segments. 
         [0026]    The sealing plates advantageously have in each case a circumferential displacement lock which holds the corresponding sealing plate in the designated position during the designated use of the wheel disk assembly, that is to say prevents a displacement in the circumferential direction. 
         [0027]    According to one embodiment of the present invention, the sealing plates have a hole and the wheel disk has associated openings, wherein connecting elements which extend through the holes engage in the associated openings and in the process are advantageously fastened on the sealing plates. Thanks to the fixing of the connecting elements on the sealing plates, an unnecessary weakening of the wheel disk as a result of notch effect or the like is prevented. The opening is advantageously designed in the form of a radially extending elongated hole. Correspondingly, the sealing plates can move radially outward under the influence of a centrifugal force during the designated use of the wheel disk assembly. 
         [0028]    According to one embodiment of the invention, a multiplicity of edges and corners of the first annular slot and/or of the support protrusions and/or of the filler piece are provided with radii. As a result of such radii, a weakening of the corresponding component as a result of notch effect is avoided. 
         [0029]    The present invention furthermore creates a method for installing a wheel disk assembly according to the invention, in which method all the blade devices are fastened on the wheel disk in a first step, and the sealing plates are mounted in a further step. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    Further features and advantages of the present invention will become clear based on the following description with reference to the attached drawing. 
           [0031]    In an exemplary embodiment for a wheel disk assembly according to the invention: 
           [0032]      FIG. 1  shows a perspective view of a wheel disk assembly; 
           [0033]      FIG. 2  shows a perspective view of the wheel disk in the region of the recess; 
           [0034]      FIG. 3  shows a cross section through the wheel disk in the region of the recess; 
           [0035]      FIG. 4  shows a view similar to  FIG. 2  with sealing plate inserted; 
           [0036]      FIG. 5  shows an enlarged perspective sectional view through the recess with sealing plate and inserted filler piece; 
           [0037]      FIG. 6  shows a cross section for the embodiment from  FIG. 5 ; 
           [0038]      FIG. 7  shows a side view of the filler piece for  FIG. 5 ; 
           [0039]      FIG. 8  shows a perspective view for  FIG. 5 ; 
           [0040]      FIG. 9  shows a perspective sectional view similar to  FIG. 5  with an alternative design of the recess and of the filler piece. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0041]      FIGS. 1 to 8  show a wheel disk assembly  1  and its components according to a first embodiment of the present invention. The wheel disk assembly  1  comprises a wheel disk  2 , a plurality of blade-devices  3  which are fastened along the outer circumference on a blade-locating section  24  of the wheel disk  2  in associated axially extending blade-root-locating slots  4 , and a plurality of sealing plates  5  which are retained between the wheel disk  2  and the blade devices  3  in radially spaced-apart annular slot and annular slot segments  6 ,  7 . The annular slot  6  is in this case provided in the wheel disk  2  and is delimited axially outward by means of a continuous annular projection  8 . Formed opposite thereto in each case in the blade devices  3  is an annular slot segment  7 . 
         [0042]    The annular slot  6  which is provided in the wheel disk  2  is of undercut design and, as seen in cross section, has an axially projecting retaining projection  9  which projection  9  is provided with a retaining surface  10 . Correspondingly, the sealing plates  5  in an edge region on the inside diameter, as seen in cross section, have an axially projecting support projection  11  which is designed to correspond to the retaining projection  9  and which projection  11  is provided with a support surface  12 . 
         [0043]    For facilitating the mounting of the sealing plates  5 , two recesses  13  (of which recesses  13  only one recess  13  is shown in the figures), which are diametrically opposite each other and of identical design and in each case define a sealing-plate-locating region, are arranged on the annular slot  6 . The length of the recess  13  in the circumferential direction is greater than the width of the sealing plates in the edge region which is accommodated in the annular slot  6 . The recess  13  extends in the axial direction and widens the annular slot  6 . The annular projection  8 , on the side facing the first annular slot  6  in the region of the recess  13 , has a bevel  14  which bevel  14  is designed in such a way that the annular projection  8  is flattened toward the annular slot  6 . 
         [0044]    The wheel disk assembly  1  also comprises a filler piece  15  which filler piece  15  is designed in such a way that it fills out the region which is widened in relation to the annular slot  6  by the recess  13  as well as the region of the bevel  14 . Furthermore, the filler piece  15  has a projection  16  which axially points away from the annular projection  8 , extending beneath a sealing plate, and therefore defines an axially extending contact surface which serves for the location of an inner circumferential edge of at least one sealing plate  5 . The recess  13  which also extends radially into the wheel disk  2  breaks up the base of the annular slot  6  which is otherwise provided in an encompassing manner for the seating for the sealing plates  5 . By means of the axial contact surface, a basically flush seating for the sealing plates  5  in the region of the recess  13  is created. 
         [0045]    The sealing plates  5  are designed identically in each case and comprise a hole  17  in each case through which hole  17  extends a connecting element  18  of basically pin-like design in the designated installed state of the wheel disk assembly  1 , which connecting element  18  is fastened on the associated sealing plate  5  and engages in an opening  19 , in the form of a radially extending elongated hole, which is formed on the wheel disk  2 . 
         [0046]    During the installation of the wheel disk assembly  1 , all the blade devices  3  are mounted on the wheel disk  2  in a first step. In a further step, the sealing plates  5  are installed one after the other. To this end, each sealing plate  5  is inserted by its edge region from above into the recess  13  and then tilted in the direction of the wheel disk  2 . After that, the sealing plate  5  can be moved upward, i.e. radially outward, then inserted by its outer circumferential edge into the annular slot segments  7  and then moved in a guided manner in the circumferential direction between the annular slot  6  and the annular slot segments  7 . In this case, the individual sealing plates  5  are first of all pushed one on top of the other in the circumferential direction into overlapping regions so that after the mounting of the last sealing plate  5  the sealing-plate-mounting region which is defined by the recess  13  remains free. In a further step, the filler piece  15  is then inserted into the recess  13 . Next, the sealing plates  5 , which are arranged adjacently to the recess  13 , are to be pushed in each case in the circumferential direction one onto the other so that in each case they lie half on the projection  16  of the filler piece  15 . Now the filler piece  15  is secured against an inadvertent detachment by means of the overlying sealing plates  5 . In a further step, the connecting elements  19  are pushed through the holes  17  of sealing plates  5  so that the connecting elements  19  engage with the associated openings  18  which are positioned in each case in alignment with the holes  17 . The connecting elements  19  are then fastened, for example by peening, to the sealing plates  5 . Now the sealing plates  5  are secured against an inadvertent displacement in the circumferential direction. 
         [0047]    During the designated operation of the wheel disk assembly, a centrifugal force acts upon the sealing plates  5 , which leads to the sealing plates  5  moving radially outward, wherein the connecting elements  19  are guided inside the associated openings  18 . The radially outward movement of the sealing plates  5  is limited by the support projections  11 , which are formed on the sealing plates  5 , as soon as the support surfaces  12  of the support projections  11  come to butt against the retaining surfaces  10  of the retaining projections  9  of the wheel disk  2 . In this state, the wheel disk  2  then absorbs the forces which are created by the natural weight of the sealing plates  5 . 
         [0048]    An essential advantage of the previously described wheel disk assembly  1  exists in the fact that the sealing plates  5 , thanks to the recesses  13 , can be threaded into the associated annular slots  6 ,  7  in a simple manner, even if all the blade devices  3  are already mounted on the wheel disk  2 , as a result of which the mounting is designed to be very flexible. By the same token, the sealing plates can also be removed again in a simple manner. A further advantage exists in the fact that forces, which under the influence of centrifugal force are created as a result of the natural weight of the sealing plates  5 , are absorbed by the wheel disk  2  thanks to the retaining projection  9  which is provided on the wheel disk  2  and to the support projections  11  which are formed on the sealing plates  5 , as a result of which the blade devices  3  are relieved of load to a high degree during operation of the wheel disk assembly  1 . 
         [0049]      FIG. 9  shows an alternative embodiment of a recess  20  and of a filler piece  21  which is inserted into the recess  20 . The recess  20  differs from the depicted recess  13  to the effect that the annular projection, on the side facing the annular slot  6  in the region of the recess  20 , has an undercut region with a cavity  22  which is open toward the recess  20 . The filler piece  21  differs from the filler piece  15  to the effect that this also fills out the undercut region, i.e. the cavity  22 , and that in contrast to the filler piece  15  there is no provision for a projection  16  pointing away from the annular projection upon which rest the sealing plates  5 . Otherwise, the embodiment shown in  FIG. 9  corresponds to the previously described wheel disk assembly  1 , which is why the same component parts or components are identified by the same designations. 
         [0050]    Although the invention has been fully illustrated and described in detail by means of the preferred exemplary embodiment, the invention is not limited by the disclosed examples and other variations can be derived by the person skilled in the art without departing from the extent of protection of the invention.