Patent Publication Number: US-7708529-B2

Title: Rotor of a turbo engine, e.g., a gas turbine rotor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application claims priority to Application No. 10 2004 051 116.0, filed in the Federal Republic of Germany on Oct. 20, 2004, which is expressly incorporated herein in its entirety by reference thereto. 
   FIELD OF THE INVENTION 
   The present invention relates to a rotor of a turbo engine, e.g., a gas turbine rotor. 
   BACKGROUND INFORMATION 
   Rotors of a turbo engine, e.g., gas turbine rotors, for example, have a rotor base member, as well as a plurality of rotor blades rotating with the rotor base member. The rotor blades may either be an integral component of the rotor base member, or may be anchored in one or more grooves of the rotor base member via blade roots. Rotors having integral blading are known as blisk or bling, depending upon whether the rotor base member is disk-shaped or ring-shaped. For rotors in which the rotor blades are anchored in a groove via blade roots, a distinction is made between rotors in which the blade roots of the rotor blades are secured either in so-called axial grooves of the rotor base member or in a circumferential groove of the same. An example embodiment of the present invention relates to a rotor of a turbo engine, e.g., a gas turbine rotor, in which the rotor blades are secured by their blade roots in a groove of the rotor base member extending in the circumferential direction, thus in a circumferential groove. 
   For rotors in which the rotor blades are secured by their blade roots in so-called circumferential grooves, the circumferential grooves have at least two diametrically opposed feed openings, in order to introduce the blade roots of the rotor blades into the corresponding circumferential groove. Conventionally, the feed openings may be formed by neckings in the region of groove-wall side pieces or limbs of the circumferential groove, the blade roots abutting with bearing flanks against the groove-wall side pieces during operation. Due to the feed openings, notch locations are formed on the groove-wall side pieces, which may be subject to a high level of stress during operation of the rotor. The service life of the rotor may thereby be reduced. Furthermore, conventionally, because of the design principle of rotor blades guided in circumferential grooves described above, the blade roots of the rotor blades, viewed in the circumferential direction, may have only approximately half the width of blade platforms of the rotor blades. Because of this, the forces which the blade roots are able to receive during operation of the rotor may be limited. The range of application of conventional rotors, in which the rotor blades are guided and secured via their blade roots in so-called circumferential grooves, may therefore be limited. 
   SUMMARY 
   An example embodiment of the present invention may provide a rotor of a turbo engine in which the groove and the blade roots have a profile, such that the blade roots of the rotor blades are insertable into the circumferentially extending groove of the rotor base member by a tilting motion or swiveling motion, a width of the blade root corresponding approximately or roughly to a width of the blade platform of the specific rotor blade in the circumferential direction. 
   A rotor of a turbo engine may be provided, in which the rotor blades are guided and secured via their blade roots in a circumferential groove, but in which the groove, e.g., the groove-wall side pieces, have no feed openings minimizing mechanical strength. Rather, the groove and the blade roots have a profile which may allow the blade roots to be inserted into the groove by a tilting motion. Moreover, the blade roots may be dimensioned such that, in the circumferential direction, a width of the blade roots corresponds approximately to the width of the blade platform of the specific rotor blade. Therefore, strength-minimizing feed openings in the region of the groove may be avoided, and the blade roots may be able to take up greater forces because of their markedly greater extension in the circumferential direction. The range of application of rotors in which the rotor blades are guided in circumferential grooves may thereby be expanded. 
   In the radial direction, a relative position between the rotor blades and the rotor base member may be defined by spacers, the spacers being positioned between groove-wall side pieces of the groove extending in the circumferential direction and the blade platforms of the rotor blades. 
   The spacers may be in the form of hump-like projections, a plurality of hump-like projections being positioned at a distance from each other on both groove-wall side pieces of the groove in the circumferential direction. In each case, two rotor blades may be supported with their blade platforms on two opposing projections positioned on different groove-wall side pieces. A securing element, which defines a relative position between the rotor blades and the rotor base member in the circumferential direction, may extend through in each case two opposing, hump-like projections positioned on different groove-wall side pieces. 
   Formed as a spacer on one groove-wall side piece of the groove may be a projection that is closed in the circumferential direction of the groove, extends in the radial direction and is an integral component of the groove-wall side piece. Positioned as a spacer on the other groove-wall side piece of the groove may be a closure ring closed in the circumferential direction or a closure ring segmented in the circumferential direction, which is insertable between the groove-wall side piece and the platforms of the rotor blades and is fixed in position by a retaining ring. 
   Formed as a spacer on one groove-wall side piece of the groove may be a projection that is closed in the circumferential direction of the groove, extends in the radial direction and is an integral component of the groove-wall side piece. Formed as a spacer on the other groove-wall side piece of the groove may be a projection that extends in the circumferential direction of the groove, is interrupted by at least one opening and is an integral component of the groove-wall side piece. 
   According to an example embodiment of the present invention, a rotor of a turbo engine includes: a rotor base member including a groove extending in a circumferential direction of the rotor base member; and a plurality of rotor blades, each rotor blade including a blade, a blade root and a blade platform positioned between the blade and the blade root, the rotor blade anchored in the groove by the blade root. The groove and the blade root are profiled so that the blade root is insertable into the groove by one of (a) a tilt motion and (b) a swivel motion, in the circumferential direction, a width of the blade root corresponding approximately to a width of the blade platform. 
   The rotor may be arranged as a gas turbine rotor. 
   A relative position between the rotor blades and the rotor base member in a radial direction may be defined by spacers. 
   The spacers may be positioned between groove-wall side pieces of the groove and the blade platforms of the rotor blades. 
   The spacers may include projections positioned on at least one side of the groove. 
   The projections may include a plurality of projections positioned at a distance from one another in the circumferential direction on at least one groove-wall side piece of the groove, a recess formed between adjacent projections. 
   The projections may include a plurality of projections positioned at a distance from one another in the circumferential direction on both groove-wall side pieces of the groove, and two rotor blades may be supported with the blade platforms on each of two opposing projections positioned on different groove-wall side pieces of the groove. 
   The rotor may include securing devices that define a relative position in the circumferential direction between the rotor blades and the rotor base member, and the securing devices may extend through two opposing projections positioned on different groove-wall side pieces of the groove. 
   The securing devices may include rivets. 
   The projections may be integral to the groove-wall side pieces and may extend radially outwardly starting from the groove-wall side pieces. 
   The spacer on one groove-wall side piece of the groove may include a projection that is closed in the circumferential direction of the groove, extends in the radial direction and is integral to the groove-wall side piece. 
   The spacer on another groove-wall side piece of the groove may include one of (a) a closure ring that is closed in the circumferential direction and (b) a closure ring that is segmented in the circumferential direction, is insertable between the another groove-wall side piece and the platforms of the rotor blade and is immobilized by a retaining ring. 
   The spacer on another groove-wall side piece of the groove may include a projection that extends in the circumferential direction of the groove, is interrupted by at least one opening and is integral to the another groove-wall side piece. 
   According to an example embodiment of the present invention, a gas turbine includes at least one rotor as described above. 
   The gas turbine may be arranged as a gas turbine of an aircraft engine. 
   Exemplary embodiments of the present invention are explained in greater detail below with reference to the appended Figures. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective side view of a segment from a conventional gas turbine rotor. 
       FIG. 2  is a perspective view of a segment from a gas turbine rotor of an example embodiment of the present invention. 
       FIG. 3  is a cross-sectional view through the gas turbine rotor illustrated in  FIG. 2 , during the mounting of a rotor blade on a rotor base member of the gas turbine rotor. 
       FIG. 4  is a cross-sectional view through the gas turbine rotor illustrated in  FIG. 2  having a mounted rotor blade. 
       FIG. 5  is a cross-sectional view through a gas turbine rotor according to an example embodiment of the present invention having a mounted rotor blade. 
       FIG. 6  is a cross-sectional view through a gas turbine rotor according to an example embodiment of the present invention having a mounted rotor blade. 
       FIG. 7  is a cross-sectional view through a gas turbine rotor according to an example embodiment of the present invention having a mounted rotor blade. 
       FIG. 8  is a cross-sectional view through the gas turbine rotor illustrated in  FIG. 7 . 
       FIG. 9  is a perspective view of a closure element of the gas turbine rotor illustrated in  FIGS. 7 and 8 . 
   

   DETAILED DESCRIPTION 
   A conventional gas turbine rotor having rotor blades guided in a circumferential groove is illustrated in  FIG. 1 . 
     FIG. 1  illustrates a segment from a gas turbine rotor  10 , gas turbine rotor  10  being formed by a rotor base member  11  and a plurality of rotor blades  12 . According to  FIG. 1 , each rotor blade  12  has a blade  13  and a blade root  14 , a blade platform  15  being formed between blade  13  and blade root  14 . Rotor blades  12  are secured or guided via their blade roots  14  in a groove  16  of rotor base member  11 , groove  16  extending in the circumferential direction. Groove  16  extending in the circumferential direction is open radially outwardly and is bounded by two opposite groove-wall side pieces or limbs  17  and  18 , respectively. To be able to insert rotor blades  12  by their blade roots  14  into circumferential groove  16 , recesses or notches  19  which form feed openings for blade roots  14  are introduced into groove  16 , i.e., groove-wall side pieces  17 ,  18 . To insert rotor blades  12  into circumferential groove  16 , rotor blades  12  are accordingly slipped by their blade roots  14  into circumferential groove  16  in the region of notches  19 , and then shifted in the circumferential direction. After the last rotor blade  12  in gas turbine rotor  10  illustrated in  FIG. 1  has been inserted, the entire set of rotor blades  12  is shifted by one half spacing of blades in the circumferential direction, so that all contact surfaces of blade roots  14  are located below supporting groove-wall side pieces  17  and  18 , and therefore not in the region of a recess or notch  19  of groove-wall side pieces  17 ,  18 . It follows directly from this that, viewed in the circumferential direction, blade roots  14  have only approximately half the width of blade platforms  15 . 
     FIGS. 2 to 4  illustrate a gas turbine rotor  20  according to an example embodiment of the present invention, having a rotor base member  21  and a plurality of rotor blades  22 . Rotor blades  22  each have a blade  23 , a blade root  24  and a blade platform  25  arranged between blade  23  and blade root  24 . Rotor base member  21  has a groove  26  extending in the circumferential direction and bounded by lateral groove-wall side pieces or limbs  27  and  28 , respectively, rotor blades  22  being guided with their blade roots  24  in groove  26  extending in the circumferential direction. In the assembled state (see, e.g.,  FIG. 4 ), blade roots  24  abut against groove-wall side pieces  27  and  28 , forming so-called bearing flanks  29 . 
   Circumferential groove  26  and blade roots  24  have a profile, such that blade roots  24  of rotor blades  22  are insertable into circumferential groove  26  of rotor base member  21  by a tilting motion or swiveling motion, and e.g., without neckings or notches which may minimize mechanical strength being necessary in groove-wall side pieces  27  and  28 , respectively. In  FIG. 3 , a double arrow  30  illustrates the tilting motion or swiveling motion of rotor blade  22  upon insertion of its blade root  24  into circumferential groove  26 . Moreover, the profile of blade roots  24  of rotor blades  22  is dimensioned such that, in the circumferential direction, a width of blade roots  24  corresponds approximately or roughly to a width of specific blade platform  25  of specific rotor blade  22 . Due to the profiling of circumferential groove  26  and of blade roots  24 , strength-minimizing notches in groove-wall side pieces  27  and  28  may be omitted, and the circumferential extension of bearing flanks  29  may be markedly increased compared to conventional systems. This may increase the service life of gas turbine rotor  20 . 
   As already mentioned, after rotor blades  22  have been pivoted by blade roots  24  into circumferential groove  26  in accordance with double arrow  30 , rotor blades  22  are aligned relative to rotor base member  21  such that blade roots  24  abut against groove-wall side pieces  27  and  28  of groove  26 , forming bearing flanks  29 . In this context, in the radial direction, a relative position between rotor blades  22  and rotor base member  21  is defined by spacers, the spacers being positioned between groove-wall side pieces  27  and  28  extending in the circumferential direction and blade platforms  25  of rotor blades  22 . 
   As illustrated in  FIGS. 2 to 4 , the spacers may be in the form of hump-like projections  31  which extend on both sides of groove  26 , and accordingly are positioned in the region of both groove-wall side pieces  27  and  28 . Viewed in the circumferential direction, a plurality of hump-like projections  31  are formed with distance from one another on both sides of circumferential groove  26 . Therefore, in each case, a recess  32  is formed between two hump-like projections  31  adjacent in the circumferential direction. Multiple hump-like projections  31  are accordingly positioned at a distance from one another in the circumferential direction in the region of both groove-wall side pieces  27  and  28 . In each case, two rotor blades  22  are supported with their blade platforms  25  on two opposite, hump-like projections  31  positioned on different groove-wall side pieces  27  and  28 . Thus,  FIG. 2  illustrates that each rotor blade  22  is supported at one end via its platform  25  on two hump-like projections  31  which are positioned on different groove-wall side pieces  27  and  28 . At the opposite ends of blade platforms  25 , they are not supported on hump-like projections  31 , but rather extend in the region of a recess  32  between projections  31  set apart from each other in the circumferential direction. 
   Therefore, in the mounted state of rotor blades  22 , the spacers, formed in the exemplary embodiment illustrated  FIG. 2 to 4  as hump-like projections  31 , define a radial relative position of rotor blades  22  with respect to rotor base member  21 , such that rotor blades  22  are prevented from shifting radially inwardly. In the exemplary embodiment illustrated in  FIGS. 2 to 4 , hump-like projections  31  are each an integral component of corresponding groove-wall side piece  27  and  28 , respectively, and extend radially outwardly starting from respective groove-wall side piece  27  or  28 . 
   In the circumferential direction, the relative position between rotor blades  22  and base member  21  of gas turbine rotor  20  is defined by securing elements  33  that, in each case, extend through two opposite, hump-like projections  31  positioned on different groove-wall side pieces  27  and  28 . In the exemplary embodiment illustrated in  FIGS. 2 to 4 , securing elements  33  may be in the form of rivets supported in bore holes  34  of hump-like projections  31 . In the exemplary embodiment illustrated in  FIG. 4 , securing element  33 , formed as a rivet, is fixed in its position by bending over a tip  35  of securing element  33  in accordance with arrow  36 . Blade root  24  of each rotor blade  22 , at the side at which it borders on securing element  33 , has an indentation or recess  37  through which securing element  33  may be inserted, and which predefines the mounting position of rotor blades  22  in rotor base member  21 . 
   In the exemplary embodiment illustrated in  FIGS. 2 to 4 , the gas turbine rotor includes a guidance of the blade roots of the rotor blades in a circumferential groove of the rotor base member, in which no strength-minimizing notches may be necessary in the groove-wall side pieces of the circumferential groove. Rather, the circumferential groove and the blade roots are profiled such that the blade roots may be introduced into the circumferential groove by a tilting motion, and the width of the blade roots in the circumferential direction corresponds approximately to the width of the respective blade platform, and therefore markedly larger bearing flanks may be made possible between the blade roots and the groove-wall side pieces compared to conventional systems. In the radial direction, the relative position between the rotor blades and the rotor disk base member is defined by spacers in the form of hump-like projections that may be an integral component of the groove-wall side pieces. In the circumferential direction, the relative position is defined by securing elements that extend through two opposite, hump-like projections positioned on different groove-wall side pieces. 
   An aspect of this design of a gas turbine rotor compared to conventional systems is that it may be possible to eliminate feed openings, required according to conventional systems, in the groove-wall side pieces which may reduce the mechanical strength and the service life of the blade/rotor connection. A further aspect is that markedly larger bearing flanks may be made possible between the blade roots and the groove-wall side pieces, which means the compressive load per unit area in the region of the bearing surfaces, and therefore the danger of so-called fretting, may be reduced. Gas turbine rotors hereof may be able to take up perceptibly higher forces during operation than conventional rotors, e.g., thereby increasing service life and enlarging a range of applications. 
     FIG. 5  illustrates a gas turbine rotor  38  according an example embodiment of the present invention. The exemplary embodiment illustrated in  FIG. 5  corresponds for the most part to the exemplary embodiment illustrated in  FIGS. 2 to 4 , so that to avoid unnecessary repetitions, the same reference numerals are used for the same or similar structural components. In the following, only those details are discussed which differentiate the exemplary embodiment illustrated  FIG. 5  from the exemplary embodiment illustrated in  FIGS. 2 to 4 . Thus, the exemplary embodiment illustrated in  FIG. 5  differs from the exemplary embodiment illustrated in  FIGS. 2 to 4  only by the form of securing element  33 , which, in the exemplary embodiment illustrated in  FIG. 5 , is implemented as a symmetrical rivet. With regard to the remaining details, reference is made to the explanations concerning the exemplary embodiment illustrated in  FIGS. 2 to 4 . 
     FIG. 6  illustrates a gas turbine rotor  39  according to an example embodiment of the present invention. The same reference numerals are used in  FIG. 6  for the same or similar structural components, and in the following, only those details are discussed which differentiate the exemplary embodiment illustrated in  FIG. 6  from the exemplary embodiment illustrated in  FIGS. 2 to 4 . Thus, the exemplary embodiment illustrated in  FIG. 6  differs from the exemplary embodiment illustrated in  FIGS. 2 to 4  due to the form of the spacers which define the relative position of rotor blades  22  with respect to rotor disk base member  21  in the radial direction. In the exemplary embodiment illustrated in  FIG. 6 , on one groove-wall side piece  27  of circumferential groove  26 , a first spacer is formed as a projection  40  closed in the circumferential direction of groove  26 . Projection  40  is an integral component of groove-wall side piece  27  and, starting from groove-wall side piece  27 , extends radially outwardly in the direction of platform  25  of rotor blade  22 . As already mentioned, in the exemplary embodiment illustrated in  FIG. 6 , projection  40  is closed in the circumferential direction. Used as a spacer in the region of opposite groove-wall side piece  28  is a closure ring  41  closed in the circumferential direction or a closure ring  41  segmented in the circumferential direction, which is inserted between groove-wall side piece  28  and platforms  25  of rotor blades  22 , and is fixed in this position by a retaining ring  42 . Closure ring  41  provides protection against rotation and tilting for rotor blades  22 . 
     FIGS. 7 to 9  illustrate a gas turbine rotor  39  according to an example embodiment of the present invention. The same reference numerals are used in  FIGS. 7 to 9  for the same or similar structural components, and in the following description, only those details are discussed which differentiate the exemplary embodiment illustrated in  FIGS. 7 to 9  from the exemplary embodiment illustrated in  FIGS. 2 to 4 . Thus, the exemplary embodiment illustrated in  FIGS. 7 to 9  again differs from the exemplary embodiment illustrated in  FIGS. 2 to 4  due to the form of the spacers which define the relative position of rotor blades  22  with respect to rotor disk base member  21  in the radial direction. In the exemplary embodiment illustrated in  FIGS. 7 to 9 , on one groove-wall side piece  27  of circumferential groove  26 , a first spacer is formed as a projection  43  closed in the circumferential direction of groove  26 . Projection  43  is an integral component of groove-wall side piece  27  and, starting from groove-wall side piece  27 , extends radially outwardly in the direction of platform  25  of rotor blade  22 . As already mentioned, in the exemplary embodiment illustrated in  FIGS. 7 to 9 , projection  43  is closed in the circumferential direction. Used as a spacer in the region of opposite groove-wall side piece  28  is a projection  44  that extends in the circumferential direction of groove  26 , is interrupted by at least one opening  45 , and is an integral component of groove-wall side piece  28 . In the region of each opening  45 , the relative position in the circumferential direction between rotor blades  22  and base member  21  of gas turbine rotor  20  is defined by a securing element  46 . Securing elements  46  are formed by a rivet  47  and a closure element  48  for opening  45 , closure element  48  cooperating with rivet  47 . As illustrated in  FIGS. 7 and 8 , securing elements  46  extend through projections  43  and  44  in the region of groove-wall side pieces  27  and  28 . In the exemplary embodiment illustrated in  FIGS. 7 to 9 , projection  44  may be interrupted by two or four openings  45 , in each case two openings  45  being diametrically opposed, and each opening  45  being closed by a closure element  48  of a securing element  46 . 
   List of Reference Numerals 
   
       
         10  gas turbine rotor 
         11  rotor base member 
         12  rotor blade 
         13  blade 
         14  blade root 
         15  blade platform 
         16  groove 
         17  groove-wall side piece 
         18  groove-wall side piece 
         19  notch 
         20  gas turbine rotor 
         21  rotor base member 
         22  rotor blade 
         23  blade 
         24  blade root 
         25  blade platform 
         26  groove 
         27  groove-wall side piece 
         28  groove-wall side piece 
         29  bearing flank 
         30  double arrow 
         31  projection 
         32  recess 
         33  securing element 
         34  bore hole 
         35  tip 
         36  arrow 
         37  recess 
         38  gas turbine rotor 
         39  gas turbine rotor 
         40  projection 
         41  closure ring 
         42  retaining ring 
         43  projection 
         44  projection 
         45  opening 
         46  securing element 
         47  rivet 
         48  closure element