EP3219911A1 - Gas turbine rotor with bolted rotor discs - Google Patents

Abstract

The invention relates to a rotor of a gas turbine with a compressor section and with a central section and with a turbine section, wherein the turbine section comprises a plurality of rotor disks (01). The rotor disks (01) have positive-locking and / or frictional torque-transmitting means on the mutually facing end faces (07). Adjacent rotor disks (01) are screwed together by means of a plurality of fastening bolts (15, 16) distributed in the circumference. An improved connection is achieved by the use of a spur gear (08) as a torque transmission means.

Description

The invention relates to a rotor of a gas turbine, which has a compressor section, a central section and a turbine section, wherein at least in the turbine section a plurality of rotor disks are present. Here, at least two rotor disks are connected to each other by means of fastening bolts.

The rotor of a gas turbine usually has a compressor section, a central section and a turbine section. The compressor section in this case regularly comprises in several stages successively arranged compressor blade rings. Similarly, the turbine section is also mapped in a known manner of several stages, wherein also in each stage, a plurality of turbine blades are arranged distributed in the circumference. It is customary here for the turbine blades to be attached interchangeably to the respective turbine stage.

The connection of the individual turbine stages of the turbine section with each other can also take place here in different ways. Thus, in simple embodiments, it is possible to combine several or all turbine stages integrally (without the rotor blades) in one component in a non-detachable manner. Alternatively, embodiments are also known in which a plurality of turbine disks are used, each with one or two blade rings. Here, the turbine disks must be connected to each other in such a way that both a sufficient bending stiffness of the rotor is ensured, and the torque can be transmitted from one turbine disk to the next turbine disk.

For this purpose, in turn, various solutions from the prior art are known, wherein the individual turbine disks in one proven variant are bolted together. Alternatively, a central tie rod for simultaneous connection of all turbine disks is often used, in the present case, this solution should not be considered further. When screwed together turbine disks a plurality of fastening screws in the circumference is arranged, by means of which two turbine disks are screwed together on flanges.

In such screwed embodiments is usually provided that the torque between the individual turbine disks is transmitted by friction. The required pressure is achieved by the screw. Furthermore, it is necessary to ensure a centering of the turbine disks relative to the axis of rotation. For this purpose, a turbine disk is usually provided with an annular contact shoulder in each case, in which engages a collar on the subsequently flanged turbine disk.

Although the individual turbine disks can be reliably connected to each other by means of screwing, the problem nevertheless arises in the production of the rotor that the individual turbine disks are to be centered as precisely as possible on each other and, to that extent, the tolerance between the plant shoulder and the collar is kept as low as possible. Furthermore, the transmission of the torque via frictional engagement requires a correspondingly high pressure in the screw connection of the turbine disks.

Object of the present invention is therefore to reduce the effort to connect the turbine disks. The stated object is achieved by an embodiment according to the invention according to the teaching of claim 1.

Advantageous embodiments are the subject of the dependent claims.

The generic rotor initially serves for use in a gas turbine. Here, it is required that the rotor has a compressor section, a center section, and a turbine section. At least the turbine section in this case again has at least two, advantageously a plurality, of rotor letters, wherein a plurality of rotor blades are distributed in the circumference on at least one rotor disk. Whether further the compressor section is made in one piece or analogous to the turbine section also has a plurality of rotor disks is initially irrelevant. At least it is necessary for two adjacent rotor disks to have positive-locking and / or frictional torque-transmitting means on mutually facing end faces.

Furthermore, it is necessary that the adjacent rotor disks have a plurality of circumferentially distributed mounting holes. It is provided that the adjacent rotor disks are connected to each other by means of the mounting holes penetrating fastening bolts. Here, in a first variant, it may be provided that in each case two rotor disks are connected to one another by means of the fastening bolts. In an alternative variant, it is possible that between two rotor disks, which are each provided with circumferentially distributed blades, another rotor disk is arranged without blades, wherein by means of fastening bolts these three rotor disks are screwed together at the same time.

According to the invention, the transmission of the torque between the individual bolted rotor disks is thereby improved by using an end toothing between the bolted rotor letters as the torque transmission means.

The use of a spur gearing reduces the requirement for the pressure to be applied by the fastening bolts, as now substantially the torque positively transmitted through the spur toothing and no longer purely due to a frictional force.

To improve the centering of the individual rotor disks to each other and in particular to avoid the requirement of a tight toleranced fit between a contact shoulder and a collar, the spur toothing is executed in a particularly advantageous manner such that it causes a centering of the rotor disks to one another. Here, a Hirth toothing can be used in a particularly advantageous manner. By using the Hirth toothing, a direct centering of the rotor disks bolted together takes place. Thus, the need for a fit between the individual rotor discs is unnecessary. Likewise, the use of Curvic gearing is possible.

An optimal connection between the individual rotor discs, taking into account both the transmission of the torque in the spur toothing and also taking into account the flexural rigidity of the rotor, it is also advantageous if the fastening bolts are arranged in the region of the spur toothing. This means that the fastening bolts are at least in the immediate vicinity of the spur toothing. This is the case if the distance between the spur toothing and the fastening bolts is not greater than corresponds to the radial width of the spur toothing. Advantageous for this purpose is a distance which is smaller than corresponds to the diameter of the fastening bolt. It is particularly advantageous if the fastening bolts penetrate the spur toothing at least in sections.

As the attachment of the fastening bolt is initially irrelevant. In a first variant, it is possible to carry out the fastening bores in a rotor disk or alternately the fastening bores in both rotor disks as threaded bores into which the fastening bolts are screwed directly. In a second variant it is also possible to provide the mounting holes as through holes, wherein at the end of the fastening bolt either an integral screw head or a fastening nut is arranged.

When installing it is to be considered that when using the self-centering spur a slight displacement of the individual rotor discs to each other when tightening the mounting bolts. To this - even if it is only the slightest angular deviations - to allow a displacement of the mounting bolts when tightening, a screw head or a fastening nut is provided in a particularly advantageous manner on the mounting hole facing side directly or indirectly has a dome-shaped collar surface , Due to the dome-shaped collar surface, an angular offset between the plane perpendicular to the axis of rotation and the axis of the fastening bolt is made possible.

It is initially irrelevant whether the dome-shaped collar surface surrounding the fastening bolt is arranged directly on the screw head or on the fastening nut or whether it is advantageously arranged on a washer, which consequently has a planar surface on the side facing the screw head or fastening nut Can have surface. In a particularly advantageous combination, the screw head on a dome-shaped collar surface, while on the other hand, a dome-shaped washer is arranged on the fastening nut.

For this purpose, in a particularly advantageous manner, the rotor disk directly or indirectly on a dome-shaped contact surface complementary to the collar surface. It is also initially irrelevant whether the dome-shaped contact surface is integrated directly surrounding the mounting hole in the surface of the rotor disk or whether in this case a washer is used in an advantageous manner, on which the contact surface is arranged. In that sense, the dome-shaped contact surface are formed both by the washer and by an integrated on the rotor disc Kalotten reduction. Insofar as the manufacturing methods allow, a Kalottensenkung is advantageous over a washer.

In which area the spur gearing is arranged, initially irrelevant. At least this is to be arranged for the advantageous transmission of torque to the largest possible diameter. In an embodiment in which the fastening bolts are arranged at a distance from the spur toothing for connecting the fastening flanges, it is furthermore particularly advantageous if there is a free space between the fastening flanges and the adjacent rotor disks in the region of the fastening bores. Whether this space is provided in two mounting flanges or is only arranged in a mounting flange, this is irrelevant. It is necessary that the mounting flanges adjacent to the free space opposite to the spur toothing again abut each other. Thus, a pressure force generated during clamping of the fastening bolts distributed on the one hand on the one side of the free space remaining area of the mounting flanges with contact with each other and on the other hand on the opposite spur toothing. In this case, it is advantageous to arrange the fastening bolts outside at a small distance from the spur toothing. The clearance surrounding the fastening bolts is advantageously made annular, with an annular bearing ring remaining outside the annular clearance.

When starting the gas turbine, a heating process occurs in the rotor and thus in the rotor disks. This heating does not take place uniformly over all rotor disks, but individual rotor disks are subjected to a greater thermal expansion than adjacent rotor disks. This leads in a natural way to a shift within the spur toothing of the adjacent rotor discs together. Around If necessary, to limit displacement, a limiting ring is used in an advantageous manner, which engages with radial play in opposing limiting grooves present in the fastening flanges. If the thermal expansion of a rotor disk, in contrast to the adjacent rotor disk, reaches an inadmissibly high value, the limiting ring is abutted on opposite flanks of the opposite limiting grooves.

In a further advantageous embodiment, taking into account the screw connection, it is provided that the spur toothing does not start from an end face which is planar in the simplest case, but that at least one end face, from which the spur toothing is machined in the rotor disc, has a position changing in the axial direction. In a particularly advantageous manner, the end face corresponds to a circumferential around the rotor axis waveform. Here, the mounting holes are arranged in a direction away from the opposite rotor disk trough the front side, while the intermediate peaks of the front side are arranged at the greatest distance between two mounting holes. The tooth height of the spur toothing is advantageously carried out in accordance with the spur toothing in a planar end face, only just starting from the wave-shaped end face. That in the non-bolted state, the spur gear is in the range of the greatest distance between the mounting holes, while with increasing approach to the mounting holes, an increasing gap occurs within the spur gear teeth.

It is particularly advantageous if, in the screwed state of the two rotor disks, the deformation of the fastening flanges caused by the tensile stress in the fastening bolts leads to a circumferentially complete contact with the face gear. The design is simplified when the deformation of the mounting flange with the deformation of the front side starting from the waveform to a planar front side leads. That is, by screwing the two mounting flanges a previously existing gap within the spur toothing between the two rotor discs closes and in a particularly advantageous manner a circumferentially uniform surface pressure in the spur toothing is generated.

For producing a face gear with a rotationally alternating position of the teeth of the spur gear, it is advantageous if the rotor disc opposite a machining by milling or grinding by means of a revolving eccentric or other actuating means in the direction of the machining tool during rotation of the rotor disc at the same time according to the waveform of the front side is raised and lowered by the amount required to adjust the position of the teeth.

For optimum material utilization of the fastening bolt and in particular of the fastening nut, it is furthermore particularly advantageous if the most uniform transfer of load in the thread takes place from the fastening nut to the fastening bolt. For this purpose, it is particularly advantageous if the fastening nut has a bearing ring on the side facing the contact surface, which has an enlarged inner diameter relative to the fastening bore. This means that the fastening nut rests only on the outer periphery on the contact surface. In the case of a convexly curved contact surface, this leads to the effect that expansion of the fastening nut takes place on the side facing the contact surface, whereby the otherwise highly loaded thread near the contact surface is relieved.

The newly created embodiment makes it possible to use a proven screwing of the individual rotor disks and yet to accomplish a problem-free structure of a rotor without major effort with respect to the centering of the individual rotor disks to each other by an advantageous self-centering spur gearing. Farther is achieved by the direct screwing of the rotor disks by means arranged in the region of the spur gearing mounting bolts best possible load transfer both in terms of torque to be transmitted as well as with respect to a bending load of the rotor.

In the following figures, exemplary solutions for a screw connection of rotor disks according to the invention are outlined.

• Figur 1 einen Schnitt durch mehrere miteinander verschraubte Rotorscheiben mit einer Stirnverzahnung;
• Figur 2 eine analoge Ansicht zur Figur 1 in perspektivischer Darstellung;
• Figuren 3,4 eine beispielhafte Verschraubung von Rotorscheiben mit Beilagscheibe und Unterlegscheibe;
• Figuren 5,6 eine alternative Ausführungsform mit einer Befestigungsschraube mit kalottenförmigem Kopf
• Figuren 7,8 eine alternative Ausführungsform mit einem Freiraum zwischen den Rotorscheiben;
• Figur 9 eine alternative Ausführungsform mit einem Begrenzungsring;
• Figur 10 eine alternative Ausführungsform mit spannungsoptimierter Befestigungsmutter.

Show it:

• FIG. 1 a section through a plurality of rotor disks screwed together with a spur toothing;
• FIG. 2 an analogous view to FIG. 1 in perspective view;
• Figures 3,4 an exemplary screw connection of rotor disks with washer and washer;
• Figures 5,6 an alternative embodiment with a fastening screw with calotte-shaped head
• FIGS. 7,8 an alternative embodiment with a clearance between the rotor discs;
• FIG. 9 an alternative embodiment with a limiting ring;
• FIG. 10 an alternative embodiment with tension-optimized fastening nut.

In the FIG. 1 By way of example, the screw connection of rotor disks 01 of a rotor of a gas turbine is outlined. In the following FIG. 2 the example turns off FIG. 1 shown in perspective view.

Evident are the plurality of rotor disks 01, which 01 each have a blade carrier portion 03 in the outer region. How the individual blades are attached to the rotor disk 01, is irrelevant in terms of the invention. At least it is provided that the rotor has at least two rotor disks 01, which each have a plurality of circumferentially distributed blades, which are fastened to the blade carrier portion 03. Following the blade carrier section 03 is the gear section 04, which 04 establishes the connection between the individual rotor disks 01 and the torque is transmitted via the 04. In the direction of the axis of rotation, the stabilizing section 05 connects, which 05 is to prevent deformation, in particular bending or torsion of the individual rotor disks 01.

Each rotor disk 01 has on both sides a front side 07 facing the following rotor disk 01. At this end face 07 a Hirth serration 08 is arranged in this embodiment in each case (being omitted for reasons of simplified illustration on the representation of the Hirth serration on the right and left end). The Hirth serration 08 causes both a centering of each successive rotor disks 01 to each other and also the torque from one rotor disk 01 to the subsequent rotor disk 01 can be transmitted. For connecting the two rotor disks 01, it is provided that each rotor disk has an attachment flange 10 which extends outward on the end face 07. In these 10 are distributed in the circumference, a plurality of mounting holes 11 through which 11 each a fastening bolt 15 is inserted. By means of fastening nuts 20 a screwing of the rotor disks 01 takes place.

The FIGS. 3 and 4 Now show a first embodiment of the realization of the screw connection between the individual rotor disks 01st

The FIG. 3 shows here in detail the adjacent rotor disks 01 with the respective mounting flange 10, in which the mounting hole 10 is 10. This outlines the FIG. 4 a view prior to the attachment of the fastening nuts 20. Through the mounting hole 11 in the mounting flange 10 through the fastening bolt 15 extends, wherein at both ends of the fastening bolt 15 each fastening nuts 20 are arranged. For advantageous angular compensation of the fastening bolts 15 in the self-centering of the rotor disks 01 to each other by means of Hirth serration 08 is between the respective mounting flange 10 and the fastening nuts 20 is a dome-shaped washer 14 and a dome-shaped washer 22. With regard to the curvature of the dome-shaped discs 14, 22 result There are two possibilities, wherein a concave washer 22a has a concave collar surface 21a on the left-hand side. Complementary to this is the convex contact surface 13b on the convex washer 14b. On the right hand side, the analogous example is shown with the concave washer 14a, which has the concave bearing surface 13a, for which purpose the convex washer 22b with the convex collar surface 21b is arranged below the fastening nut 20.

In the FIGS. 5 and 6 becomes analogous to FIGS. 3, 4 an alternative embodiment for screwing the rotor disks 01 sketched. Evident is the arrangement of the rotor disks 01 with the abutting on the end faces 07 mounting flanges 10, in each of which the mounting holes 11 are located. In contrast to the previous embodiment, a fastening bolt 16 is used in this case, which 16 is provided with a convex screw head 17. For this purpose, the fastening nut 20 with the convex washer 22b is located at the opposite end. The fastening bolt 16 in this case has on the convex screw head 17 on the convex collar surface 21b. Complementary to the convex collar surface 21b forms in this embodiment, the mounting flange 10 directly by means of a concave Kalottensenkung 12, the concave contact surface 13 a. Opposite, the fastening nut 20 is used with the convex washer 22b analogous to the previous embodiment.

In the following FIGS. 7 and 8 a further embodiment of a rotor with rotor disks 31 screwed together is sketched in section or in perspective analogous to the previous views. These rotor disks initially correspond to the previous embodiment with a Hirth toothing 33 for transmitting torque between the two rotor disks 31. Furthermore, the rotor disks 31 are connected in the same way by a fastening bolt in the region of the fastening flanges 32. In contrast to the previous exemplary embodiment, provision is now made in that a free space 35 is present between the Hirth toothing 33 and the outer circumference of the fastening flange 32. This 35 is limited to the outer periphery by a support ring 34, at the 34, the mounting flanges 32 in turn abut each other. Now takes the attachment of the rotor disks 31 to each other, leads in an obvious way, the clamping of the mounting bolt to a support of the mounting rings 34 and the Hirth gear 33 to each other. Thus, a better pressure in the Hirth serration 33 can be achieved.

In the FIG. 9 a further embodiment of a rotor according to the invention with the rotor disks 41 is sketched. In contrast to the previous exemplary embodiment, in the region of the Hirth toothing 43, these have a delimiting ring 45, which engages in the opposite rotor disks 41 in each case into a delimiting groove 44. It is provided that the limiting ring 45 is mounted with radial clearance in the Begrenzungsnut 44. If thermal expansions occur in a rotor disk 41 in contrast to the adjacent rotor disk 41, then the limiting ring 45 leads to a limitation of the thermal expansion of the rotor disks 41 relative to one another.

In the following FIG. 10 a particular embodiment of an advantageous fastening nut 25 is outlined. In order to optimize the load transfer in the thread between the fastening nut 25 and the fastening bolt 15, it is provided in this embodiment that the fastening nut 25 does not rest on the support surface 13b over its full area, but rather only with a support ring 26. This support ring 26 has a relation to the fastening bore 11 enlarged inner diameter, so that a reduced outer annular bearing surface is formed. It is provided that the contact surface 13b on the rotor disk 04 has an outwardly convex convex shape. If now the clamping of the fastening nut 25 on the fastening bolt 15, the annular bearing surface 26 initially leads generally due to the increased inner diameter and in particular due to the convex shape of the contact surface 13b to a widening of the fastening nut 25 at the end of the fastening nut 25 facing the contact surface 13b in turn leads to a relief of the thread in the region of the contact surface 13b, so that a more uniform transmission of the tensile force over the entire length of the thread in the fastening nut 25 is achieved.

Claims (11)

Rotor of a gas turbine with a plurality of rotor disks (01,31,41), wherein at least one rotor disk (01,31,41) a plurality of blades are arranged distributed in the circumference, wherein at least two adjacent rotor disks (01,31,41) to each other pointing end faces (07) positive and / or frictional torque transmission means and a plurality of circumferentially spaced mounting holes (11), wherein in each case two rotor discs (01,31,41) and / or two outer blades provided with rotor blades with a mean blade-free Rotor disc are connected to each other by means of a plurality of circumferentially distributed fastening holes (11) penetrating fastening bolts (15, 16),
characterized,
in that the torque transmission means are formed by a spur toothing (08, 33, 43). Rotor according to claim 1,
characterized,
that the spur toothing (08,33,43) is a Hirth toothing; and or
that the spur toothing (08,33,43) causes a centering of the rotor discs (01,31,41) to each other. Rotor according to claim 1 or 2,
characterized,
in that the fastening bolts (15, 16) are arranged in the area of the spur toothing (08, 33, 43), wherein in particular the fastening bolts (15, 16) penetrate the spur gear teeth (08, 33, 43) at least in sections. Rotor according to one of claims 1 to 3,
characterized,
that at the ends of the fastening bolt (15,16) there is arranged a screw head (17) or a fastening nut (20,25) which (17, 20.25) on the side facing the bolt hole side directly or indirectly, a dome-shaped collar surface (21, 26). Rotor according to claim 4,
characterized,
in that one or both collar surfaces (21, 26) are arranged on a washer (22). Rotor according to claim 4 or 5,
characterized,
that the rotor disc (01,31,41) to a collar surface (21,26) which directly or indirectly complementary dome-shaped contact surface (13). Rotor according to claim 6,
characterized,
in that one or both contact surfaces (13) is arranged on a washer (14) or is formed by a countersink (12). Rotor according to one of claims 1 to 7,
characterized,
that the rotor disks (01,31,41) in the region of the fixing bores (11) between the spur gearing (08,33,43) and adjacent to the outer peripheral support ring (26) have a clearance (35) end face. Rotor according to one of claims 1 to 8,
characterized,
in that the rotor disks (01, 31, 41) have a limiting groove (44) at the end, wherein a delimiting ring (45) engages with radial clearance in the opposite delimiting grooves (44). Rotor according to one of claims 1 to 9,
characterized,
that the end teeth (08,33,43) with voltage-free fastening bolt has a varying gap in circulation between the two rotor discs in a state. Rotor according to one of claims 1 to 10,
characterized,
that the rotor disc (01,31,41) on the end face, directly or indirectly, to the mounting hole (11) surrounding convex bearing surface (13), wherein a fastening nut (25) on to the bearing surface (13) facing side a bearing ring (26) having an opposite the diameter of the mounting hole (11) enlarged inner diameter.

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