Patent Publication Number: US-8979497-B2

Title: Blade arrangement, especially stator blade arrangement

Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
     Priority is claimed to Swiss Patent Application No. CH 01787/10, filed Oct. 27, 2010, the entire disclosure of which is hereby incorporated by reference herein. 
     FIELD 
     The invention relates to a blade arrangement, especially to a stator blade arrangement, on a wall of a fluid flow path of a turbomachine, especially of a gas turbine. 
     BACKGROUND 
     EP 1 803 900 A1 shows a locking sub-assembly with which the remaining gap between a first and a last blade of a blade ring, which are inserted in a circumferential groove of a turbomachine, is to be closed. In this case, it essentially concerns a two-piece intermediate piece which is arranged between the roots of the first and the last blade and which can be clamped by means of screw elements against the undercut flanks of the circumferential groove. 
     EP 1 548 232 A1 shows the arrangement of stator blades of a turbomachine, wherein the stator blades have stator blade roots which are seated in a form-fitting manner in a circumferential groove, having undercut flanks, of a stator blade carrier. Between adjacent stator blade roots, filling pieces, which determine the spacing of the stator blade roots in the circumferential direction, are arranged in the circumferential groove. In order to fix the filling pieces without clearance, provision is made on the base of the circumferential groove for groove-like recesses with annular pressure segments, arranged therein, which force the filling pieces away from the base of the circumferential groove which accommodates them so that the filling pieces, by corresponding profiles, butt against the undercut flanks of the circumferential groove in a force-locking manner. The pressure segments can make installation or removal of the filling pieces considerably more difficult. 
     GB 2156908 A relates to a rotor arrangement of a turbomachine. In this case, it is intended to insert the rotor blades of the rotor by correspondingly formed rotor blade roots into a rotor-side locating channel, wherein the rotor blade roots, by corresponding profiles, are retained in a form-fitting manner in undercuts on the flanks of the channel. For securing the rotor blade roots in the longitudinal direction of the channel, provision is made for a locking piece which, by means of a clamping screw, can be clamped in a form-fitting and force-locking manner between the undercuts of the flanks of the channel and the base of the channel. 
     U.S. Pat. No. 5,522,706 also relates to the securing of rotor blade roots, specifically in the longitudinal direction of a rotor-side channel which accommodates the rotor blade roots. In this case, locking pieces are arranged on both sides of a rotor blade root, which locking pieces are installed after arranging the rotor blade roots in the channel and can be fixed inside the channel between flank-side undercuts and the base of the channel by means of clamping elements, which are not described in more detail (in the drawing, clamping screws are shown only by way of indication). At no point is it shown or indicated that the locking pieces are to fill out the locating channel for the rotor blade roots between the rotor blades to form a surface which is essentially free of disturbing contours. 
     EP 1 865 153 A2 shows the arrangement of rotor blades on a compressor disk. This has a circumferential channel, with undercut flanks, which accommodates correspondingly matched rotor blade roots in a form-fitting manner. For securing the rotor blade roots, a locking piece is arranged inside the locating channel and, in the inserted state, fits beneath undercut flanks of the locating channel and, by means of a clamping screw which engages in a recess on the base of the channel, can be clamped inside the channel in a force-locking and form-fitting manner. Here also, it is neither shown nor indicated that the locking piece could form a surface between the adjacent rotor blades which is free of disturbing contours. 
     The prior art shows no blade arrangement in which filling pieces, which are arranged between adjacent blades or between their roots, form a surface between the blades which is essentially free of disturbing contours on the one hand, and on the other hand can be clamped inside an undercut locating channel in a form-fitting and force-locking manner. 
     SUMMARY OF THE INVENTION 
     In an embodiment, the present invention provides a blade arrangement on a wall of a fluid flow path of a turbomachine. The arrangement includes a locating channel disposed in the wall and having undercut flanks A plurality of blades each having a blade-side root section corresponding to the undercut flanks A plurality of intermediate filling pieces correspond to the undercut flanks and separate each of the blade-side root sections. The plurality of blade-side root sections and intermediate filling pieces are seated in a form-fitting manner and fixed in a force-locking manner in the locating channel. The plurality of intermediate filling pieces fill out the locating channel so as to form a gas flow-side surface essentially free of a disturbing contour between the blade-side root sections. Each of the plurality of intermediate filling pieces includes a threaded hole disposed essentially perpendicular to a base of the channel. A screw is disposed in the threaded hole, the screw being adjustable so as to be clampable against the base of the channel 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be described in even greater detail below based on the exemplary figures. The invention is not limited to the exemplary embodiments. Other features and advantages of various embodiments of the present invention will become apparent by reading the following detailed description with reference to the attached drawings which illustrate the following: 
         FIG. 1  shows a perspective view of a compressor casing segment with locating channel and blading accommodated therein, 
         FIG. 2  shows a plan view of this casing segment corresponding to the arrow II in  FIG. 1 , 
         FIG. 3  shows a sectional view corresponding to the line of intersection III-III in  FIG. 2 , and 
         FIG. 4  shows a sectional view corresponding to the line of intersection IV-IV in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     In an embodiment, the present invention provides a blade arrangement on a wall of a fluid flow path of a turbomachine, especially of a gas turbine, wherein in a locating channel—formed in the wall—with undercut flanks, correspondingly matched blade-side root sections and intermediate filling pieces, which separate the root sections, are seated in a form-fitting manner and fixed in a force-locking manner for mounting of the blades. 
     In embodiment, the invention provides a new mounting for the blading of a turbine or the like. 
     In particular, an easy exchangeability of the intermediate filling pieces is to be ensured in the process. 
     To this end, it is provided according to an embodiment of the invention that the intermediate filling pieces have threaded holes which are essentially perpendicular to the base of the channel and with screws screwed into them, which screws, by means of screw adjustment, can be clamped against the base of the channel. 
     An embodiment of the invention is based on the general idea of arranging screws on the intermediate filling pieces, with which the intermediate filling pieces can be fixed in the locating channel in a force-locking manner. The screws, moreover, are captively arranged. 
     Since in this way each intermediate filling piece can be clamped separately in the locating channel, each intermediate filling piece can be adjusted and fixed independently of other filling pieces. Furthermore, removal of the intermediate filling piece is also easily possible. 
     In other respects, with regard to preferred features of the invention, reference is to be made to the claims and to the subsequent explanation of the drawing, on the basis of which a preferred embodiment of the invention is described in more detail. 
     Protection is claimed not only for the disclosed or depicted feature combinations but also for principally any combinations of the disclosed or depicted individual features. 
     The invention shall subsequently be explained in more detail with reference to an exemplary embodiment and to  FIGS. 1 to 4 . 
     According to  FIG. 1  and  FIG. 2 , a compressor casing segment  1 , on its side facing the gas flow which is to be compressed, has a locating channel  2  with encompassing ribs  9 . In this case, in the depicted example, undercuts  10  are formed by means of the rib-like projections which are arranged on the flanks of the channel. Inserted into the locating channel  2  are stator blades  3  with root sections  11  which are formed on them and matched to the cross section of the locating channel  2 . Arranged in each case between the root sections  11  of adjacent stator blades  3  are intermediate filling pieces  4  which are matched to the cross section of the channel, and on the one hand fill out the channel  2  so that the casing segment  1  maintains a surface on the gas flow side which is essentially free of disturbing contours. On the other hand, a predetermined spacing between adjacent stator blades  3  is ensured by means of the intermediate filling pieces  4 . 
     According to  FIGS. 3 and 4 , the intermediate filling pieces  4  are penetrated in each case by a threaded hole which is essentially perpendicular to the base of the locating channel  2  and accommodates a screw  5 . This threaded hole, on the side of the intermediate filling pieces  4  facing the base of the channel, opens into a recess  6  which is arranged there, which recess is open towards the base of the channel and is able to accommodate an end piece  7  which is arranged on the screw  5 . On the end of the screw  5  facing away from the end piece  7 , provision is made for a hexagon socket  8  or the like for the positioning of a screw-rotating tool with which the screw  5  can be screw-adjusted in the threaded hole of the intermediate filling piece  4 . According to an embodiment of the invention, it is now intended to clamp the screws  5 , by means of the aforesaid screw-rotating tool, by their end pieces  7  against the bottom of the locating channel  2 . In this way, the form-fit of the respective intermediate filling piece  4  with the undercuts  10  on the flanks of the locating channel  2  (encompassing ribs  9 ), is made to be clearance-free, with force-locking fixing of the respective intermediate filling piece  4 . 
     In the example of  FIG. 4 , rib-like projections  9  are formed on the flanks of the channel  2  and project into corresponding grooves on the flanks of the intermediate filling pieces  4 . If, by means of screw-adjustment, the screw  5  by its end piece  7 , or head, is now clamped against the base of the locating channel  2 , a corresponding pressure acts between the lateral face of the rib  9  facing the base of the channel and the lateral face of the groove, formed in the intermediate filling piece  4 , which faces the lateral face of the rib. 
     Providing the screw  5 , in the clamped state of the intermediate filling piece  4 , projects by its threaded portion from the upper side of the intermediate filling piece facing away from the base of the channel, an aftermachining is carried out in order to ensure an end face which is in alignment with the upper side of the intermediate filling piece  4 . If necessary, said upper side of the intermediate filling piece  4  can also be aftermachined in order to ensure a smooth transition to the adjacent surfaces of the casing segment  1 . In this way, a boundary surface which is free of disturbing contours for the fluid flow of the turbomachine is created between the stator blades. 
     The screw  5  is secured against loosening. 
     While the invention has been described with reference to particular embodiments thereof, it will be understood by those having ordinary skill the art that various changes may be made therein without departing from the scope and spirit of the invention. Further, the present invention is not limited to the embodiments described herein; reference should be had to the appended claims. 
     LIST OF REFERENCE NUMERALS 
     
         
           1  Compressor casing segment 
           2  Locating channel 
           3  Stator blades 
           4  Intermediate filling pieces 
           5  Screw 
           6  Recess 
           7  End piece 
           8  Hexagon socket 
           9  Encompassing ribs, rib-like projections 
           10  Undercut 
           11  Blade-side root section