Patent Publication Number: US-2020291798-A1

Title: Rotor disk assembly having a two-part seal

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is the US National Stage of International Application No. PCT/EP2017/056776 filed Mar. 22, 2017, and claims the benefit thereof. The International Application claims the benefit of German Application No. DE 102016205921.1 filed Apr. 8, 2016. All of the applications are incorporated by reference herein in their entirety. 
    
    
     FIELD OF INVENTION 
     The invention relates to a rotor disk assembly having a rotor disk and sealing elements which are arranged in front of an end face. 
     BACKGROUND OF INVENTION 
     In a rotor of a gas turbine, use is made as a rule of rotor disks which have a multiplicity of blade retention grooves, distributed on the outer circumference, into which a rotor blade is fastened in each case by means of a blade retention profile. This enables the exchange of rotor the rotor blade in the case of wear. It is furthermore known that the blade retention grooves are to be protected against penetration of the hot gas which flows through the gas turbine. To this end, circumferentially distributed segmented sealing plates are inserted in a known manner in front of the end face of the rotor disk. To this end, known embodiments are known for example from EP 1 804 338 A1, EP 1 944 471 A1 and from EP 2 399 004 A1. The sealing plates usually have a flat design in these cases and extend from an annular groove beneath the blade retention grooves beyond the outer circumference of the rotor disk. Therefore, the blade retention grooves are reliably covered by the sealing plates. The fastening of the sealing plates is carried out on the rotor disk or on the rotor blades in different ways, wherein to this end the sealing plates are usually mounted on the inner circumference in an annular groove of the rotor disk. The axial securing of the sealing plates on the outer circumference is usually similarly carried out in an annular groove which is formed by the circumferentially segmented adjacent rotor blades. 
     Although a suitable covering of the blade retention grooves on the rotor disk is possible using the available embodiments of sealing plates, narrow limits are set, due to the high thermal loads, upon the possibility of enhancing the sealing plates by further functions without giving rise to an appreciable cost increase. In particular, the requirement for a further sealing leg, extending radially in front of the end face, leads to the necessity of using an expensive material for the sealing plates. 
     SUMMARY OF INVENTION 
     It is therefore the object of the presented invention to enable the attachment of an additional sealing leg without the costs increasing to a considerable degree. 
     The set object is achieved by means of an embodiment according to the invention of a rotor disk assembly. A rotor according to the invention is specified and a gas turbine according to the invention is specified. Advantageous embodiments are the subject matter of the dependent claims. 
     The generic rotor disk assembly comprises in the first instance a rotor disk. This has a multiplicity of axially extending blade retention grooves which are distributed on the outer circumference. In this case, it is not absolutely necessary that the blade retention grooves extend parallel to the rotor axis, although this constitutes the advantageous and inexpensive embodiment. Rather, it is sufficient if the blade retention grooves extend from one end face of the rotor disk to the other end face of the rotor disk. In this case, these can have both a curved characteristic and advantageously a rectilinear characteristic. Furthermore, the rotor disk, at least on a side in front of the end face beneath the blade retention grooves, has an encompassing plate retention groove or a plurality of circumferentially distributed plate retention grooves. 
     The rotor disk assembly also comprises a multiplicity of sealing plates which in a circumferentially distributed manner form a basically closed ring. In essence, reference is made in this respect to the fact that a slight gap, which is advantageously arranged in the region between two blade retention grooves, can remain between the individual sealing plates. The sealing plates have in this case a flat design and extend transversely to the rotor axis. In this case, it is not absolutely necessary that the sealing plates have a constant material thickness over their extent. It is at least provided that the material thickness in the axial direction is significantly smaller than its dimensions in the radial and tangential directions. The sealing plates are mounted in the rotor disk assembly by their respective inner circumference in the plate retention groove. Therefore, their movement is limited at least in the axial direction. In accordance with their task, the sealing plates in this case cover the blade retention grooves in certain sections. 
     According to the invention, it is now provided that a multiplicity of sealing vanes are used. These sealing vanes, as additional sealing elements, supplement the sealing plates for covering the blade retention grooves. Correspondingly, the multiplicity of separate sealing vanes also form an encompassing, basically closed ring, wherein the sealing vanes are also arranged in front of the end face of the rotor disk. In order to achieve a covering of the blade retention grooves which is as complete as possible, the sealing vanes are furthermore arranged directly adjacent to the sealing plates, wherein the sealing plates are located adjacent to the sealing vanes on the side pointing toward the rotor axis. 
     By dividing the conventionally used sealing elements for covering the blade retention grooves into inner sealing plates and sealing vanes located above them, a greater degree of freedom with regard to material choice and design is achieved. The sealing plates can now be produced from an inexpensive material, while on the other hand there is the possibility in the case of the sealing vanes of adding further functions in a specific manner. 
     In this case, it is particularly advantageous if the sealing plates are produced in each case from a metal sheet. In this way, a particularly inexpensive production method is achieved by for example the sealing plates being stamped out or lasered out of a metal sheet. 
     In contrast, it is advantageous if the sealing vanes, in a cross section along the rotor axis, are of an O-shaped or V-shaped radially outwardly opening design. Therefore, it is made possible to form two spaced apart vane legs, which extend radially in each case, on the sealing vane. 
     It is also advantageous with regard to logistics and installation if all the sealing plates used on the rotor disk assembly are designed as identical parts. 
     Similar to the sealing plates, it is also advantageous if all the sealing vanes used in the rotor disk assembly are designed as identical parts. 
     With regard to the segmented division of the sealing surface and the sealing vanes, it is possible on the one hand to arrange these in a coinciding number and, moreover, one above the other in each case. It is advantageous, however, if the sealing plates and the sealing vanes are positioned in a staggered manner in relation to each other as seen in the rotation direction. Furthermore, it is advantageous if the number of sealing vanes and sealing plates vary in relation to each other. 
     For the fastening of the sealing vanes, it is advantageous if a multiplicity of circumferentially distributed mounting bases are arranged on the rotor disk. These mounting bases extend in this case in a particularly advantageous manner beyond the end face of the rotor disk beyond the sealing plate in the axial direction. In a simple and advantageous manner the mounting bases are arranged in this case between two blade retention grooves in each case. When the corresponding mounting base is being installed, the sealing vane has at least one fastening socket in which the mounting base is located. Correspondingly, the sealing vane is fastened on the rotor disk by locating the mounting base in the fastening socket. 
     The designing of the mounting base can in this case be carried out in many ways. In the both advantageous and simple embodiment, the respective mounting base is formed as a section of a rotor body in each case. This simplifies the production of the rotor disk and the installation of the sealing vanes. 
     It is also advantageous if the free end of the mounting base has a shorter distance to the rotor axis than the mounting base on the end face of the rotor disk. For secure retention of the sealing vanes on the mounting bases, it is particularly advantageous in this case if the mounting base is in proximity to the rotor axis on the underside, pointing toward the rotor axis, in the extent from the end face to the free end of the mounting base. With regard to this, it is unimportant whether the proximity extends continuously or discontinuously. 
     The mounting base in cross section can be designed in many ways and can have for example a T-shaped design. Of advantage, however, is a trapezoidal shape, as seen in cross section, which becomes larger from the end face toward the free end. Therefore, when the sealing vane is being mounted onto the mounting bases a secure retention both in the axial direction and in the radial direction is enabled. 
     In this case, it is particularly advantageous if the sealing vane has at least two fastening sockets with a free space in between. With regard to this, it is unimportant whether the sealing vane furthermore has one or two additional free spaces on both sides of the fastening sockets or whether the number of fastening sockets and free spaces is further increased. With rotation of the sealing vane relative to the rotor disk, the free space which lies between the fastening sockets at least enables mounting or removal of the sealing vane on the rotor disk. In a corresponding position of the sealing vane relative to the rotor disk, the installation of the sealing vane on the rotor disk leads to an insertion of the mounting base into the free space, wherein the mating of the mounting base in the fastening socket is subsequently carried out by the rotation of the sealing vane relative to the rotor disk. 
     Alternatively to this, it is possible to mount an individual fastening vane or a number of the existing fastening vanes or all the fastening vanes by means of an inclined movement pointing toward the rotor axis. To this end, it is necessary that the mounting base has a constant or reducing material thickness from the end face to its free end. With regard to this, the material thickness is to be determined perpendicularly to the underside of the mounting base. In this case, the fastening vane can be removed directly without rotation by means of a sliding and/or pivoting movement of the mounting base with a movement inclined toward the rotor axis. A similar method of installation is enabled if, regardless of the specific design of the mounting base, the fastening socket has an adequate free space on the side pointing away from the rotor axis so that a possible undercut on the mounting base does not hinder the installation process. 
     It is advantageous in this case if the sealing vane, which is intended for installation without a rotation, has in each case lateral edges extending parallel to each other on the sides lying opposite each other in the circumferential direction. Consequently, the installation or removal movement pointing radially toward the rotor axis does not lead to a collision of adjacent sealing vanes at the lateral edges. 
     For the advantageous fastening of the sealing plates, it is also particularly advantageous if the sealing vanes have a support surface on the side pointing toward the rotor axis. By an outer circumferential surface the sealing plates butt against this support surface, at least during rotation of the rotor disk assembly. Correspondingly, the sealing plates are radially supported by means of the sealing vanes. Therefore, a particularly simple installation and supporting of the sealing plates can be realized. 
     The shape of the support surface or of the outer circumferential surface is initially unimportant in this case providing the corresponding abutment for supporting the sealing plates is ensured. In one advantageous embodiment, it is correspondingly possible to design the support surface as part of a cylindrical surface so that a radially oriented abutment of the outer circumferential surface is ensured. It is also possible for the support surface to be of an inclined or arc-shaped design as seen in a cross section along the rotation axis, wherein in this embodiment case the support surface, similar to the underside of the mounting base, becomes closer to the rotor axis with increasing distance from the end face. 
     Particularly when selecting the support surface in cylindrical form, it is particularly advantageous if the sealing vanes have a retaining projection adjacent to the support surface. In this case, the retaining projection is arranged at a distance from the end face by the width of the support surface and extends radially in the direction of the rotor axis. Correspondingly, by means of the sealing vane together with the rotor disk a fastening groove, which is open toward the rotor axis, is realized with the groove bottom as the support surface. By the seating of the sealing plates on the outer circumference between the end face and the retaining projection these are also secured in the axial direction. 
     It is also particularly advantageous if with abutment of the sealing plates by the outer circumferential surface against the support surface of the sealing vane the mounting base and the fastening socket are designed in such a way that with rotation of the rotor disk assembly a centrifugal force of the sealing plates acts upon the support surface of the sealing vanes and therefore torque in the sealing vane is made to act around the free end of the mounting base. As a result of this, it is ensured that the sealing vane, even with a center of gravity at a distance from the end face, is not tilted downward from the mounting base toward the rotor blades on account of the high centrifugal force forces in the sealing vane. 
     For securing the position of the sealing vane or of the sealing plate on the rotor disk, a locking element is advantageously used. This fits through the sealing vane and/or the sealing plate in this case, at least in certain sections, and engages in a recess or acts against an abutment on the rotor disk or the rotor blade. In this case, it can be provided that the locking element fixes only one sealing vane or one sealing plate, wherein the locking element is advantageously arranged at the joint between sealing vane and sealing plate so that by means of the locking element at least the rotation direction of both elements is secured at the same time. 
     Furthermore, in an alternative embodiment it is possible to arrange the locking element in a fixed manner on the rotor blade, wherein this extends axially in a raised manner from the end face. In this case, by mating the corresponding rotor blade with the locking element an engagement of the locking element in a recess on the sealing vane or on the sealing plate or at least against an abutment on the sealing vane or sealing plate is enabled and therefore prevents its rotation relative to the rotor disk. 
     By realizing a rotor disk assembly with the novel inventive embodiment using sealing plates and sealing vanes, a new rotor according to the invention is created for use in a gas turbine. 
     Correspondingly, the use of a rotor according to the invention enables the realization of a gas turbine according to the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following figures, an exemplary embodiment for a rotor disk assembly is outlined. In the drawing: 
         FIGS. 1 and 2  show a detail of a rotor disk assembly according to the invention with a rotor disk, sealing plates arranged on the end face and circumferentially distributed sealing vanes arranged above them; 
         FIG. 3  shows a further perspective view of the rotor disk assembly; 
         FIG. 4  shows the rotor disk assembly similar to  FIG. 3  in section; 
         FIGS. 5 to 7  show a sealing vane of the rotor disk assembly and 
         FIG. 8  shows a sealing plate of the rotor disk assembly. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     In the following figures, an exemplary embodiment for a rotor disk assembly according to the invention is outlined. For improved perceptibility, only a detail of the rotor disk assembly is shown here, wherein the complete rotor disk assembly by itself is obviously clear to the person skilled in the art. 
     In  FIGS. 1 to 3  and also in the section in  FIG. 4 , the rotor disk  01  is first of all to be seen. This has a multiplicity of blade retention grooves  09  arranged in a circumferentially distributed manner, which blade retention grooves  09  in this exemplary embodiment are arranged rectilinearly and parallel to the rotor axis. The blade retention grooves serve for the receiving of rotor blades which are to be attached on the rotor disk  01 . The rotor disk assembly also comprises a multiplicity of sealing plates  11  arranged in a circumferentially distributed manner, which sealing plates  11  are mounted on the rotor disk  01  by their inner circumference  14  in a plate retention groove  04 . The sealing plate  11  as a separate component is shown for this purpose in  FIG. 8  and has a region on the inner circumference  14  pointing radially toward the rotor axis and a radially outer region on the outer circumference  15  and also an outer circumferential surface  12 . It is also to be seen that in this exemplary embodiment the sealing plate  11  has a recess  16  on both sides for securing the sealing plate  11  in the circumferential direction. The mounting of the sealing plate  11  on the rotor disk is advantageously to be seen in  FIG. 4 , wherein the sealing plate  11  is mounted by the inner circumference  14  in the plate retention groove which is formed radially outward from the rotor disk. In this case, the sealing plate  11  is fixed both in the axial direction. The sealing plate  11  also butts radially against the bottom of the plate retention groove  04 . As intended, the sealing plate  11  covers the blade retention groove  09  in certain sections on an end face  02  of the rotor disk  01 . As a result of this, the effect of hot gas which flows in the hot gas path of the gas turbine being able to penetrate into the lower region of the blade retention grooves  09  is largely avoided. 
     Above the sealing plates  11 , a multiplicity of sealing vanes  21  are arranged on the rotor disk  01  in a circumferentially distributed manner. These sealing vanes  21  in this case are also located in front of the end face  02  of the rotor disk  01  radially outside the sealing plates  11 . In this case, the sealing vanes  21  cover the blade retention grooves  09  on the end face in addition to the sealing plates  11 . In this way, the extensive covering of the blade retention grooves  09  is achieved by means of the sealing vanes in addition to the sealing plates  11 . For the fastening of the sealing vanes  21  on the rotor disk  01  it is provided that a multiplicity of mounting bases  03 , upon which the sealing vanes  21  are mounted, are arranged on the rotor disk  01  in a circumferentially distributed manner. To this end, the sealing vanes  21  have in each case corresponding fastening sockets  23  on the side pointing toward the rotor disk  01 . 
     As is to be seen in the views of  1  to  4 , in this exemplary embodiment the mounting bases  03 —which are arranged in each case between two blade retention grooves  09 —are of trapezoidal design and widen out with increasing distance from the end face  02  to a free end  05  of the mounting base  03 . How the mounting of the sealing vanes  21  on the rotor disk  01  is carried out, is advantageously revealed with reference to a sealing vane  21  shown separately in  FIGS. 5 to 7 . This sealing vane  21  has three fastening sockets  23  in the exemplary embodiment on the rear side pointing toward the end face  02 , which fastening sockets  23  are designed complementary to the mounting bases  03 . Located alternately with the fastening sockets  23  in each case, between these, are free spaces  24  which are dimensioned in such a way that an axial mounting of the sealing vane  21  by the free space  24  on the mounting bases  03  is possible. By rotation of the sealing vane  21  relative to the rotor disk  01  the mating of the mounting base  03  in correspondingly associated sockets  23  on the sealing vane is carried out. 
     Also to be seen in the depicted figures is the shape of the sealing vane  21  with a U-shaped, radially outward opening design. Formed as a result of this is a first vane leg  28  which points toward the end face  02  and extends radially outward, and at a distance therefrom a second radially extending vane leg  29 . For securing the sealing vane  21  in the circumferential direction, this has a recess  26  similar to the sealing plate  11 . 
     The dividing of conventional sealing elements into a radially inner sealing plate  11  and a radially outer sealing vane  21  is consequently particularly advantageously enabled by a support surface  22  being arranged on the sealing vane  21  on the side pointing radially toward the rotor axis, against which support surface  22  butts the sealing plate  11  by its outer circumferential surface  12 . In this way, the sealing plate  11  is radially fixed by means of the sealing vane  21 . Adjacent to the support surface  22 , the sealing vane  21  also has a retaining projection  25  which extends radially to the rotor axis and is arranged at a distance from the rotor disk  01 . As a result of this, it is made possible for the sealing plate  11  to be axially fixed on the outer circumference  15  between the end face  02  of the rotor disk  01  and the retaining projection  25  of the sealing vane  21 . 
     Also to be seen, especially in section in  FIG. 4 , is that the mounting base  03  extends beyond the sealing plates  11 , i.e. the free end  05  of the mounting base is further away from the end face in the axial direction than the sealing plates  11 . This, with a rotation of the rotor disk assembly with a centrifugal force in the sealing plates  11 , has the effect of the sealing plates  11  butting against the support surface  22  by the outer circumferential surface  12  and of a torque in the sealing vanes  21  around the free end of the mounting base  03  counteracting an existing torque from the sealing vanes  21  on account of their own centrifugal force. Therefore, a tensile load in the mounting base  03  as a result of the sealing vanes  21  is reduced in the axial direction. 
     Also to be seen, especially in  FIG. 1 , is that the sealing vanes  21  are arranged in each case in a staggered manner in relation to the sealing plates  11  by half a length. As a result of this, on the one hand the effect of the gaps which exist between two sealing plates  11  in each case aligning with the gaps which exist between two sealing vanes  21  in each case is avoided. Furthermore, the staggered arrangement of sealing vane  21  and sealing plate  11  enables the positioning of a locking element  07 , especially to be seen in  FIG. 4 , inside the sealing vane  21  at the same time in the corner between two sealing elements  11 . In this case, the locking element penetrates the sealing vane  21  in the region of the recess  26  and butts against the recesses  16  of the adjacent sealing plates  11 .