Arrangement for securing a functional position of a shroud plate arranged on a rotor disc relative to a moving blade arranged on the rotor disc

An arrangement for securing a functional position of a shroud plate of a rotor of a gas turbine, which shroud plate is arranged on an outer circumference of a rotor disc of the rotor, relative to a moving blade of the rotor arranged on the outer circumference of the rotor disc, wherein a channel portion of an annular cooling channel of the rotor is formed between the shroud plate located in its functional position and a side, facing the shroud plate, of a blade root of the moving blade. A rotor assembly for a rotor of a gas turbine, having a rotor disc, a moving blade ring arranged on the outer circumference of the rotor disc and a shroud plate ring arranged on the outer circumference of the rotor disc.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International Application No. PCT/EP2014/068825 filed Sep. 4, 2014, and claims the benefit thereof. The International Application claims the benefit of European Application No. EP13187993 filed Oct. 10, 2013. All of the applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention relates to an arrangement for securing a functional position of a shroud plate of a rotor of a gas turbine, which shroud plate is arranged on an outer circumference of a rotor disc of the rotor, relative to a moving blade of the rotor arranged on the outer circumference of the rotor disc, wherein a channel portion of an annular cooling channel of the rotor is formed between the shroud plate located in its functional position and a side, facing the shroud plate, of a blade root of the moving blade.

The invention further relates to a rotor assembly for a rotor of a gas turbine, comprising a rotor disc, a moving blade ring arranged on the outer circumference of the rotor disc and a shroud plate ring arranged on the outer circumference of the rotor disc.

The invention further relates to a rotor for a gas turbine and to a gas turbine.

BACKGROUND OF INVENTION

An arrangement of the above-stated type is known for example from publication WO 2010/094539 A1. To secure a functional position of a shroud plate of a rotor of a gas turbine, which shroud plate is arranged on an outer circumference of a rotor disc of the rotor, relative to a moving blade of the rotor arranged on the outer circumference of the rotor disc, said publication proposes inserting a locking element into an opening formed in the manner of keyhole in the shroud plate, which locking element engages in its functional position in a hole arranged on a side, facing the shroud plate, of a blade root of the moving blade. This functional position of the locking element is secured in that, in a given rotational position relative to the shroud plate, the locking element engages behind the edge of the opening on the blade root side by means of a cam formed on the locking element and in that the locking element located in this rotational position is secured against rotation relative to the shroud plate about a longitudinal axis of the locking element. Securing of the rotational position of the locking element is achieved in that part of the locking element is deformed plastically and thereby engages in a bit opening of the keyhole-like opening.

SUMMARY OF INVENTION

The object of the invention is to provide a novel and simple way of securing functional positions of shroud plates of a rotor of a gas turbine, which shroud plates are arranged on an outer circumference of a rotor disc of the rotor, relative to moving blades of the rotor arranged on the outer circumference of the rotor disc.

The arrangement according to the invention for securing a functional position of a shroud plate of a rotor of a gas turbine, which shroud plate is arranged on an outer circumference of a rotor disc of the rotor, relative to a moving blade of the rotor arranged on the outer circumference of the rotor disc, wherein a channel portion of an annular cooling channel of the rotor is formed between the shroud plate located in its functional position and a side, facing the shroud plate, of a blade root of the moving blade, comprises—a web which may be arranged on the side of the blade root facing the shroud plate, which web may be arranged in such a way on the blade root that the web extends radially relative to the rotor disc when the moving blade is arranged on the rotor disc,—a guide portion, which may be formed by a thickened portion formed on the shroud plate, and a guide opening, which may be formed by a through-hole arranged on the shroud plate, wherein the guide portion at least partially surrounds the guide opening,—a securing bolt comprising a longitudinal through-hole, the external diameter of which corresponds to the diameter of the guide opening and which comprises at one end two cut-aways arranged diametrically relative to one another, open towards said end and of equal width, which cut-aways extend from said end of the securing bolt parallel to the longitudinal axis of the securing bolt over part of the length of the securing bolt, wherein the width of the cut-aways is greater than or equal to the width of the web, and—a securing device for securing a functional position of the securing bolt on the shroud plate and the moving blade.

According to the invention, the functional position of the shroud plate is secured if the securing bolt extends partly in the guide opening which may be formed on the guide portion of the shroud plate and the web is arranged at least partly in the cut-aways. This is effected in particular in that the web extends radially relative to the rotor disc when the moving blade is arranged on the rotor disc.

The thickened portion formed on the shroud plate or the guide portion which may be formed thereby allows the formation of a longer guide opening and thereby good guidance for the securing bolt. In addition, during operation of a correspondingly configured gas turbine, forces arising through contact with the securing bolt in the region of the guide opening may be better absorbed by the shroud plate as a result of the thickened portion or the guide portion, without the occurrence of damage to the shroud plate, in particular in the region of the guide opening. The guide portion in particular completely surrounds the guide opening.

The fact that the external diameter of the securing bolt corresponds to the diameter of the guide opening means that the securing bolt may be inserted form-fittingly into the guide opening.

The diametric arrangement of the cut-aways and the configuration thereof open towards the end of the securing bolt allows simultaneous insertion of the web into the two cut-aways, by pushing the securing bolt onto the web. To achieve form-fitting joints between the cut-aways and the web, the width of the cut-aways is advantageously equal to the width of the web.

The securing device for securing a functional position of the securing bolt on the shroud plate and the moving blade holds the securing bolt permanently securely in its position pushed onto the web, i.e. in its functional position. The securing device may be configured in any manner suitable for this purpose.

The arrangement according to the invention may be achieved in the course of retrofitting an existing gas turbine. In addition, the arrangement may be taken into consideration in a new gas turbine development. The most varied types of gas turbine may be provided with the arrangement according to the invention. In an embodiment, an arrangement according to the invention is provided for each shroud plate of a rotor.

The securing bolt and/or the web are formed of metal and may be suitably hardened to reduce wear to said components.

In an embodiment, the securing device comprises a groove arranged on the side of the guide portion facing the blade root, which groove extends from the guide opening radially over at least part of the guide portion, and an L-shaped, plastically deformable securing wire, wherein the diameter of the longitudinal bore of the securing bolt, the width of the groove and the width of the cut-aways are greater than or equal to the external diameter of the securing wire. One leg of the L-shaped securing wire may be introduced in this way into the longitudinal hole in the securing bolt partly arranged in the guide opening on the shroud plate, until the other leg of the securing wire is located at least partly in the groove formed on the guide portion. If the leg of the securing wire arranged at least partly in the groove simultaneously extends through one of the cut-aways on the securing bolt, the securing bolt is secured relative to the shroud plate against rotation about its longitudinal axis. To achieve optimum robustness of the arrangement, the diameter of the longitudinal bore, the width of the groove and the width of the cut-aways are advantageously equal to the external diameter of the securing wire, such that corresponding form-fitting joints may be produced between components of the arrangement.

One cut-away is advantageously longer than the other cut-away by a specified difference in length, wherein the difference in length is greater than or equal to the external diameter of the securing wire. The difference in length is advantageously equal to the external diameter of the securing wire. The length of the shorter cut-away may for example correspond to the height of the web, whereas the length of the longer cut-away may correspond to the sum of the height of the web and the external diameter of the securing wire. To simplify the production effort associated with the securing bolt, the cut-aways may alternatively be of equal length.

The web is advantageously formed in one piece with the moving blade. The web may for example be produced inexpensively together with the remainder of the moving blade using a casting method. This gives a very robust joint between the web and the remainder of the moving blade. Alternatively, the web may be produced separately and then joined to the moving blade.

The web may advantageously be arranged in a recess which may be formed on a side of the blade root facing the shroud plate. This enables axial installation space to be saved, so as to allow compact configuration of a rotor and/or of a gas turbine despite the attachment of an arrangement according to the invention to the rotor of the gas turbine.

At least one longitudinal edge of the web arranged on the side of the web remote from the blade root is advantageously provided with a chamfer. The chamfer may be formed by post-machining of the web formed on the moving blade. Advantageously, both longitudinal edges of the web arranged on the side of the web remote from the blade root are each provided with a chamfer. Formation of the chamfer or chamfers on the web enables simpler assembly of the arrangement, which is made more difficult in particular because the web is barely or not visible during assembly of the arrangement. The chamfer or chamfers on the web may result, on contact between the securing bolt or the edges of the cut-aways formed on the securing bolt and the web, in a desired forced orientation of the securing bolt relative to the web, in order to be able to push the securing bolt as desired onto the web or to move the securing bolt into its functional position.

The end of the securing bolt not provided with the cut-aways is advantageously provided, on a side facing the longitudinal hole, with rounding extending over at least part of the inner circumference of the longitudinal bore. The rounding may serve as a contact surface for plastic shaping of the securing wire, in order to bend, advantageously by 90°, an end of the securing wire remote from the blade root and projecting out of the securing bolt. This plastic deformation of the securing wire may be used to retain the securing bolt permanently in its functional position. Without the rounding at the end of the securing bolt, damage to the securing wire could occur on bending of the securing wire and/or under mechanical stresses when a correspondingly configured gas turbine is in operation. This could in turn impair the permanence of the corresponding securing of the functional position of the securing bolt.

Advantageously, at least one free end of at least one cut-away is provided with a chamfer. The chamfer may be formed by post-machining of the free end of the cut-away. Both free ends of each cut-away are advantageously in each case provided with a chamfer. Formation of the chamfer or chamfers at the cut-away or the cut-aways likewise allows simpler assembly of the arrangement, which is made more difficult in particular because the web is barely or not visible during assembly of the arrangement. The chamfers at the free ends of the cut-aways may result, on contact between the securing bolt or the chamfers formed on the securing bolt and the web, on which chamfers may likewise be formed, in a desired forced orientation of the securing bolt relative to the web, in order to be able to push the securing bolt as desired onto the web or to move the securing bolt into its functional position.

The arrangement advantageously comprises a sealing groove which may be arranged on the blade side on a sealing wing formed on a platform of the moving blade, in which sealing groove a radially outer edge portion of the shroud plate may be arranged. In the case of an arrangement properly mounted on a rotor, the radially outer edge portion of the shroud plate is introduced into part of the sealing groove. When a gas turbine equipped in this way is in operation, the shroud plate may move radially outwards and extend further into the sealing groove. The further the radially outer edge portion of the shroud plate extends into the sealing groove, the better is the shroud plate sealed relative to the sealing wing, a fact which is associated with an improvement in the sealing of an annular cooling channel of the rotor formed between the shroud plates and the blade roots. When a gas turbine is in operation, tilting movements of the platforms of the moving blades and consequently of the sealing wings of the moving blades additionally generally arise. Because of the play present in the sealing groove and the punctiform suspension of the shroud plate on the rotor by way of the securing bolt, a shroud plate may rotate about the securing bolt by a given amount, in order to be able to follow the tilting movements of the platforms by a given amount.

The rotor assembly according to the invention for a rotor of a gas turbine comprises a rotor disc, a moving blade ring arranged on the outer circumference of the rotor disc, a shroud plate ring arranged on the outer circumference of the rotor disc and at least one arrangement according to one of the above-stated configurations or any desired combination thereof. The advantages stated above with regard to the arrangement are accordingly associated with said assembly.

The rotor according to the invention for a gas turbine comprises at least one above-stated rotor assembly.

The gas turbine according to the invention comprises an above-mentioned rotor.

DETAILED DESCRIPTION OF INVENTION

FIG. 1shows a portion of a side view of an exemplary embodiment of a moving blade1according to the invention, i.e. a moving blade1which comprises a web5arranged on the side3, facing a shroud plate2shown inFIGS. 7, 8 and 9, of the blade root4of the moving blade1, which web is arranged in such a way on the blade root4that the web5extends radially relative to the rotor disc when the moving blade1is arranged on a rotor disc, not shown. The web5is arranged in a recess6formed on the side3of the blade root4facing the shroud plate2, a fact which is revealed better byFIGS. 2 and 9. The web5is formed in one piece with the moving blade1, wherein the two longitudinal edges of the web5arranged on the side of the web5remote from the blade root4are each provided with a chamfer9. A sealing wing7of a platform8of the moving blade1is arranged above the recess6.

FIG. 2shows a portion of a sectional representation of the moving blade1shown inFIG. 1corresponding to the arrow A shown inFIG. 1. On the sealing wing7of the platform8of the moving blade1, a sealing groove10is formed on the blade root side, in which sealing groove a radially outer edge portion of the shroud plate2may be arranged, as shown inFIG. 9. The web5terminates flush with the rest of the side3, facing the shroud plate2, of the blade root4, i.e. the height h of the web5corresponds to the depth of the recess6.

FIG. 3shows a perspective representation of an exemplary embodiment of a securing bolt11of an arrangement12according to the invention, as shown inFIG. 9. The securing bolt11comprises a longitudinal through-hole13and at one end two cut-aways14and15arranged diametrically relative to one another, open towards said end and of equal width. The cut-aways14and15extend from said end of the securing bolt11parallel to the longitudinal axis L of the securing bolt11over part of the length of the securing bolt11. The width bAof the cut-aways and the diameter dLof the longitudinal hole13are equal to the width bSof the web5. The free ends of the cut-aways14and15are in each case provided with a chamfer16. The end of the securing bolt11not provided with the cut-aways14and15is provided, on a side facing the longitudinal hole13, with rounding17extending over the entire inner circumference of the longitudinal hole13, which can be seen better fromFIG. 4.

FIG. 4shows a longitudinal section through the securing bolt11shown inFIG. 3. The cut-away15is longer than the cut-away14by a predetermined difference in length Δl=l2−l1. The length l1of the shorter cut-away14is equal to the height h of the web5. The difference in length Δl, the width bA of the cut-aways14and15and the width bS of the web5are equal to the diameter d of the longitudinal hole13.

FIG. 5shows an end view of the securing bolt11shown inFIGS. 3 and 4corresponding to arrow B ofFIG. 4.

FIG. 6shows a side view of an exemplary embodiment of a securing wire18of the arrangement12according to the invention. The plastically deformable securing wire18is of L-shaped construction and comprises one shorter leg19and one longer leg20. The securing wire18has a circular cross-section and is formed of metal. The securing wire18forms part of a securing device for securing the functional position, shown inFIG. 9, of the securing bolt11on the shroud plate2and the moving blade1. The length l2of the longer cut-away15is equal to the sum of the height h of the web5and the external diameter daof the securing wire. The diameter dLof the longitudinal hole13, the difference in length Δl, the width bAof the cut-aways14and15and the width bSof the web5are equal to the external diameter daof the securing wire18.

FIG. 7shows a portion of a side view of an exemplary embodiment of a shroud plate2according to the invention. A guide portion22formed by a thickened portion21formed on the shroud plate2and a guide opening24formed by a through-hole23arranged in the shroud plate2are arranged on the shroud plate2, wherein the guide portion22completely surrounds the guide opening24. The securing device comprises a groove26arranged on the side25of the guide portion22facing the blade root4, which groove extends from the guide opening24radially over the guide portion22. The width bNof the groove26is equal to the external diameter daof the securing wire18. The external diameter dSof the securing bolt11is equal to the diameter dFof the guide opening24.

FIG. 8shows a portion of a longitudinal section through the shroud plate2shown inFIG. 7, corresponding to line VIII-VIII inFIG. 7.

FIG. 9shows a portion of a sectional representation of an exemplary embodiment of an arrangement12according to the invention for securing the functional position shown of the shroud plate2of a rotor of a gas turbine, which shroud plate2is arranged on an outer circumference of a rotor disc of the rotor, relative to the moving blade1of the rotor arranged on the outer circumference of the rotor disc. A channel portion27of an annular cooling channel, not shown in any greater detail, of the rotor is formed between the shroud plate2located in its functional position and the side3, facing the shroud plate2, of a blade root4of the moving blade1.

Assembly of the arrangement12shown inFIG. 9is described below in greater detail:

First of all, the securing wire18may be pre-mounted in the securing bolt11, by inserting the longer leg20of the securing wire18into the longitudinal hole13in the securing bolt11until the shorter leg19of the securing wire18engages in the longer cut-away15of the securing bolt11. The assembly pre-assembled in this way may be pushed from the side25, facing the blade root4, of the guide portion22into the guide opening24, until the shorter leg19of the securing wire18is arranged at least in part in the groove26. In this way, the securing wire18is secured against axial rotation. Then the shroud plate2may be positioned, together with the assembly arranged thereon of securing wire18and securing bolt11, in a functional position relative to the moving blade1or the blade root4thereof. The securing bolt11may then be pushed from the side of the shroud plate2remote from the blade root4axially towards the blade root4and displaced such that the web5engages in the cut-aways14and15on the securing bolt11. Finally, the end of the longer leg20of the securing wire18projecting out of the securing bolt11may be bent radially outwards over the rounding17formed on the securing bolt11, as shown inFIG. 5. This prevents the securing bolt11from being able to move axially away from the blade root4.

Although the invention has been illustrated and described in greater detail with reference to the preferred exemplary embodiment, the invention is not restricted by the disclosed examples and other variations may be derived therefrom by a person skilled in the art without going beyond the scope of protection of the invention.