EP2867478B1 - Blade ring for a turbomachine - Google Patents

Description

The invention relates to a blade ring for an axial turbomachine comprising a blade carrier with a number of - holding flanks - holding grooves for blades and a corresponding number of blades whose corresponding to the retaining grooves blade feet are inserted into the retaining grooves, wherein the blades at one groove bottom the retaining groove facing Schaufelfußunterseite have a recess whose bottom is at least partially inclined relative to the groove bottom of the retaining groove and in each of which a wedge-shaped clamping element for pressing the blade root is arranged on the support flanks.

A generic object is for example from the EP 1 892 380 A1 known. According to the mounting of compressor blades on a rotor proposed therein, two wedges are provided for each blade between a blade root bottom and the groove bottom of the retaining groove. The inclinations of the two wedges are opposite. The front side is in each case a clamping screw screwed into the wedges, with the one hand, a radial prestressed positioning of the blade roots on corresponding support flanks of the retaining grooves is possible. On the other hand, the screw also serves to fix the blades along the retaining grooves. A resilient attachment of the blades is achieved by the fact that disc springs can be provided below the wedges.

However, it is perceived as a disadvantage that a screw is used. Due to the comparatively rough operating environment and the operating temperatures occurring, such screw connections can corrode, so that a problem-free disassembly can not be guaranteed.

Next is for example from the EP 1 703 078 A1 known, sitting in axial holding slots blades through the Use a locking plate to secure against displacement along the retaining grooves. In this case, a locking plate is placed between the blade root and the retaining groove on the groove base. By a bead on the locking plate this engages in a foot provided opening. After inserting the blade with the locking plate and the bending of the surrounding ends at the inlet and outlet sides of the foot a positive locking is achieved. In order to ensure a sufficiently biased seat of the blade in the groove during operation, the mounting of the blade must also be carried out under a bias. The assembly under bias leads to unfavorable wear and galling on the support flanks, which increases the risk of cracking. Especially in the front stages of an axially flowed compressor, so large blades, where particularly large biasing forces are required, the assembly or disassembly proves difficult in the service case of the blade.

The object of the invention is therefore to provide a blade ring for a turbomachine in which a bias-free and thus playful assembly of blades in the retaining grooves of a blade carrier is enabled and still a sufficiently large bias is present in operation, the material-damaging wear - for example, by Clatter - reliably avoids.

The task directed to the blade ring for an axial turbomachine is achieved with the features of claim 1. Advantageous embodiments are specified in the dependent subclaims. These can be combined with one another in any desired manner, provided that this is not expressly excluded by the relationships given in the patent claims.

In the blade ring for an axial turbomachine according to the invention, comprising a blade carrier with a number of - holding flanks - retaining grooves for blades and a corresponding number of blades, whose to the retaining grooves Correspondingly executed blade feet are inserted into the retaining grooves, wherein at least one of the blades, preferably all blades, on its one groove bottom of the retaining groove facing blade root underside has or have a recess whose bottom is at least partially obliquely against the groove bottom of the retaining and employed in the respective a wedge-shaped clamping element for pressing the blade root is arranged on the supporting flanks, it is provided that a spring element is provided in each recess, the spring force acts along the retaining groove on the respective wedge-shaped clamping element, wherein the recess of a first side wall and one of the first side wall opposite second wall is limited, wherein the spring element is supported on the one hand on the first side wall and on the other hand on a blunt end of the wedge-shaped clamping element and that means are provided with which the wedge-shaped clamping element for the front Tension-free assembly of the blade in the retaining groove can be temporarily moved to a position in which the blade root sits without bias in the retaining groove.

In the installed state, the spring element presses the wedge-shaped clamping element in the direction of its pointed end, which acts in conjunction with the inclined bottom of the recess, a force in the radial direction (relative to the installation position in an axial turbomachine) on the blade root, the latter to the support flanks of the retaining grooves presses. This is a backlash-free and preloaded attachment of the blade causes in the holding. The spring element is thus supported on the one hand on a first side wall of the recess and on the other hand on the blunt end of the wedge-shaped clamping element. In order to enable a preload-free disassembly or assembly of the blade in the retaining groove, it is necessary that means are provided with which the wedge-shaped clamping element can be temporarily moved to a position in which the blunt end of the wedge-shaped clamping element closer to the first Sidewall is when in the assembled state. In other words: the spring element is only compressed further for the duration of disassembly or assembly as it is provided in the assembled state. Due to the corresponding inclinations of the bottom of the recess and the wedge-shaped clamping element, the displacement of the clamping element to the first side wall relieves relief for the tension of the blade on the support flanks of the retaining. This results in a game along the axis of the groove bottom of the retaining groove in the direction of the bottom of the recess, which is both for mounting and for disassembly of the blade in or out of the retaining groove and which allows the desired bias-free handling of the blade meanwhile. Consequently, no elaborate devices for pressing or pushing the blade into the groove or from the groove are required.

Overall, this results in a simpler and faster assembly and disassembly process, which also ensures a high level of work safety for fitters. At the same time, the size of the spring force can be achieved by a simple variation of different spring elements. This gives special then, when the spring elements are designed as disc springs or cup spring packages. At the same time, the tolerance of the blade connection with blade carrier can be reduced to an average level, which allows a comparatively inexpensive production of the components.

During operation of the axial turbomachine equipped with such a blade ring, there is a constant adaptation of this biasing device to the radial position of the blade. Designed from blade rings, the blade will take its maximum radial position in the retaining groove under the action of centrifugal forces during operation. In parallel, the wedge-shaped clamping element is pressed under the action of the spring force of the spring element further under the blade. Thus, a particularly high bias of the blade is maintained even with decrease in the engine speed. This restricts the relative movements of comparatively large blades and reduces wear in the retaining grooves.

According to a first advantageous embodiment, the spring element is designed as a plate spring or cup spring package. At the same time, an opening is provided in the first side wall. At the same time a cylindrical pin is arranged at the blunt end of the wedge-shaped clamping element, which extends through both the plate spring and the disc spring package and into the opening or through the opening in the side wall. The cylindrical pin may for example be hammered into a hole arranged on the clamping element or glued there. The cylinder pin has in conjunction with the opening arranged in the side wall the function of a guide of the spring element and at the same time a backup of the wedge-shaped clamping element, so that it can not jump out of the recess unintentionally during assembly.

According to a further advantageous development, the means comprises a threaded hole arranged in the second side wall into which a mounting screw for displacing the wedge-shaped clamping element to the first side wall can be screwed from the outside. Consequently, the spring element is first slipped over the cylindrical pin of the wedge-shaped clamping element before assembly of the blade, after which the cylindrical pin is subsequently inserted into the opening arranged in the first side wall. At the same time, the wedge-shaped clamping element is inserted into the underside of the blade arranged on the blade root. Subsequently, a mounting screw with a correspondingly long threaded shaft from the outside is temporarily screwed through the present in the second side wall threaded hole, with which the wedge-shaped clamping element can be moved in the direction of the first side wall. The displacement must be so large that the wedge-shaped clamping element is completely sunk in the recess and so a game-afflicted assembly of the blade with clamping element is possible. Subsequently, the assembly thus produced is inserted into the retaining groove. After the assembly and thus the blade has assumed the predetermined position in the retaining groove, the mounting screw screwed in the second side wall can be released again, whereby the wedge-shaped clamping element is pressed by the spring element in the direction of the second side wall. Due to the inclined surface of the wedge-shaped clamping element and the corresponding bottom of the recess, the wedge-shaped clamping element is pressed into the narrowing space between groove bottom and bottom and comes on both surfaces - the groove bottom and the floor - to concern. This then results in the tension of the blade root on the support flanks of the retaining.

Instead of a threaded connection in the second side wall, for example, a bayonet connection may be provided.

According to a further preferred embodiment, the blades are each secured by means of a between a Schaufelfußunterseite and one of the Schaufelfußunterseite opposite groove base of the holding groove arranged sheet-like securing element against displacement along the retaining grooves by the ends of the sheet-like securing element rest laterally on the blade carrier. When using such an axial securing the sheet-like securing element between the groove base and the wedge-shaped clamping element is located.

More preferably, the wedge-shaped clamping element is at least partially hollow. As a result, the blade attachment becomes more elastic in the direction of prestressing and additionally enables friction damping.

Further particularly preferably, the blade ring is a blade ring, so that the blade carrier is designed as a rotor disk or shaft and the blade as a rotor blade. Nevertheless, the blade ring is also suitable for mounting vanes.

Particularly preferred is the use of the blade ring in a compressor of an axially flowed stationary gas turbine.

FIG 1

eine stationäre Gasturbine in einem Längs-Teilschnitt,

FIG 2

den Längsschnitt durch einen Schaufelkranz im Bereich einer Haltenut mit einer darin eingesetzten Schaufel gemäß eines ersten Ausführungsbeispiels,

FIG 3

die Seitenansicht auf den Ausschnitt gemäß FIG 2,

FIG 4

eine weitere Seitenansicht auf eine Haltenut mit darin eingesetzter Schaufel und

FIG 5

einen Längsschnitt analog zu FIG 2 für ein zweites Ausführungsbeispiel eines Schaufelkranzes.

Further advantages and features of the invention will be explained in more detail with reference to further embodiments. In this case, further features and advantages are specified in the description of the figures. Show it:

FIG. 1

a stationary gas turbine in a longitudinal partial section,

FIG. 2

3 shows the longitudinal section through a blade ring in the region of a holding groove with a blade inserted therein according to a first exemplary embodiment,

FIG. 3

the side view on the neckline according to FIG. 2 .

FIG. 4

a further side view of a retaining groove with inserted thereon and

FIG. 5

a longitudinal section analogous to FIG. 2 for a second embodiment of a blade ring.

In all figures, identical features are provided with the same reference numerals. Although the invention is described in detail below with reference to a blade ring of a gas turbine compressor, the invention can also be used in other turbomachinery.

FIG. 1 shows a stationary gas turbine 10 in a longitudinal partial section. The gas turbine 10 has inside a rotatably mounted about an axis of rotation 12 rotor 14, which is also referred to as a turbine runner. Along the rotor 14 follow one another an intake housing 16, a compressor 18, a toroidal annular combustion chamber 20 with a plurality of rotationally symmetrical mutually arranged burners 22, a turbine unit 24 and a turbine outlet housing 26.

The compressor 18 includes an annular compressor duct having compressor stages of blade and vane rings 44 sequentially cascaded therein. The rotor blades 14 are supported by rotor disks and face with their free end airfoils 29 an outer duct wall 42 of the compressor duct. The compressor duct discharges via a compressor outlet diffuser 36 in a plenum 38. The annular combustion chamber 20 is provided with its combustion chamber 28, which communicates with an annular hot gas duct 30 of the turbine unit 24. In the turbine unit 24 four successive turbine stages 32 are arranged. On the rotor 14, a generator or a working machine (each not shown) is coupled.

During operation of the gas turbine 10, the compressor 18 sucks through the intake housing 16 as a medium to be compressed ambient air 34 and compresses them. The compressed air is guided through the compressor outlet diffuser 36 into the plenum 38, from where it flows into the burner 22. Fuel also passes into the combustion space 28 via the burners 22. There, the fuel is burned to a hot gas M with the addition of the compressed air. The hot gas M then flows into the hot gas duct 30, where it relaxes to perform work on the turbine blades of the turbine unit 24. The energy released during this time is absorbed by the rotor 14 and used on the one hand to drive the compressor 18 and on the other hand to drive a work machine or electric generator.

FIG. 2 shows a section through a rotor disk 19 of the rotor 14 of the gas turbine 10 in the region of an axially extending retaining groove 21. The rotor disk 19 thus represents a blade carrier 46, in which along its circumference the retaining grooves 21 are evenly distributed and thereby in the axial direction of the Gas turbine extend. The retaining grooves 21 are in cross section ( 3, FIG. 4 ) are dovetail-shaped and thus each comprise two Supporting flanks 23 against which correspondingly designed contact surfaces 25 of a blade root 31 of the blades 27 abut. The blades 27 are formed as blades.

On a lower side 33 of the blade root 31, which faces a groove bottom 35 of the retaining groove 21, a recess 37 is provided. The recess 37 is bounded by a first side wall 39 and a second side wall 41 opposite the first side wall 39. In the flow direction of a medium flowing through the compressor 18, the first side wall 39 is arranged on the inflow side and the second side wall 41 is arranged downstream.

Between the bottom 33 and the groove bottom 35, a sheet-like securing element 43 is inserted in the retaining groove 21, whose ends are longitudinally slotted. In the thus resulting on both sides tab pairs are at both ends both a tab 45 both outwardly and a tab 45 inside ( 3 and 4 ), whereby a displacement of the blade 27 inserted in the retaining groove 21 is blocked.

In the recess 37, a wedge-shaped clamping element 47 is provided with a pointed end 49 and a blunt end 51. At the blunt end 51, a cylindrical pin 53 is arranged, on which in the illustrated embodiment, a total of four disc springs are threaded as a spring element 55. The cylindrical pin 53 extends into an opening 57 arranged in the first side wall 39. The bottom 59 of the recess 37 is opposite to the groove bottom 35 of the retaining groove 21, corresponding to the inclination of the in FIG. 2 shown upper surface 61 of the wedge-shaped clamping element 47 inclined.

Furthermore, a threaded hole 63 is provided in the second side wall 41, which - as well as the opening 57 - extends parallel to the retaining groove 21. In the threaded hole 63 a required for the assembly of the blade 27 mounting screw 65 can be screwed, with the help of the wedge-shaped clamping element 47 in FIG. 2 moved so far to the left can be that its blunt end 51 is positioned comparatively close to the first side wall 39. This allows the wedge-shaped clamping element 47 completely sink in the recess 37.

The assembly of the blade 27 in the retaining groove 21 then takes place as follows: First, the prefabricated sheet-like securing element 43 is inserted into the retaining groove. The sheet-like securing element 43 extends over the entire length of the retaining groove 21, wherein already two of the tabs 45 are already bent transversely to its longitudinal extent on the inflow or outflow side. The outwardly bent tab 45 serves as a stop during the insertion of the blade 27 in the retaining groove 21. At the other end of the sheet-like securing element 43 is initially only one of the two tabs 45 in the radial direction to the machine axis pre-bent. Next, the spring member 55 is placed on the cylindrical pin 53 of the wedge-shaped clamping member 47 and inserted together into the opening 57 and the recess 37. The cylindrical pin 53 then engages in the opening 57 designed as a slot. After the inclined surface 61 of the wedge-shaped clamping member 47 abuts the inclined bottom 59, then the mounting screw 65 is screwed into the threaded hole 63, so deep that the wedge-shaped clamping member 47 is pressed to the opposite side, ie in the direction of the first side wall 39 and so far, until the wedge base 67 is located within the recess. Hereby, a bias-free insertion of the blade 27 can be ensured. Subsequently, the blade 27 is inserted with the prestressed wedge-shaped clamping element 47 in the retaining groove 21. After aligning the blade 27 in the retaining groove 21, the mounting screw 65 is released and removed from the assembly. As a result, the wedge-shaped clamping element 47 is relieved of the force of the mounting screw and can press the blade 27 in the retaining groove 21 against the support flanks 23 and thus bias by the action of the axial forces of the spring element 55. Finally, the hitherto not bent tab 45 of the sheet-like securing element 43 bent in the radial direction away from the machine axis, which then secures the blade 27 against emigration from the retaining groove 21. In the event that the thus-mounted blade 27 of the retaining groove 21 must be removed, the steps are carried out in reverse order. After bending away one of the tabs 45, the mounting screw 65 is screwed into the threaded hole 63. As a result, the bias is released and the blade 27 relieved, after which they can then be easily pushed out of the retaining groove 21.

According to a second, in FIG. 5 illustrated embodiment, the wedge-shaped clamping element 47 may be at least partially hollow. The cavity 69 causes a resilient bias and thus brings in addition a friction damping with it.

In general, the invention relates to a blade ring 44 for an axial turbomachine, comprising a blade carrier 46 with a number of retaining grooves 21 and a corresponding number of blades 27, the blade roots 31 are inserted into the retaining grooves 21, wherein the blades 27 at its one groove bottom 35 of Halteut 21 facing bottom 33 each have a recess 37, the bottom 59 is at least partially opposite the groove bottom 35 of the retaining groove 21 is inclined and in each of which a wedge-shaped clamping element 47 is arranged for pressing the blade root 31 to the support flanks 23. In order to enable a non-biased mounting of the blade 27 in the retaining groove 21 and to provide a blade ring 44 which can be used without a screw in operation, it is provided that in each recess 37, a spring element 55 is provided, the spring force along the retaining 21st acting on the relevant wedge-shaped clamping element 47 and that means are provided with which the wedge-shaped clamping element 47 for the bias-free mounting of the blade 27 in the retaining groove 21 can be temporarily moved to a position in which the blade root 31 sits without bias in the retaining groove 21.

Claims (6)

1. Blade ring (44) for an axial turbomachine, comprising a blade carrier (46) having a number of retaining grooves (21) - having support flanks (23) - for blades (27) and a corresponding number of blades (27), the blade roots (31) of which, which are configured in a manner corresponding to the retaining grooves (21), are inserted into the retaining grooves (21),
   wherein at least one of the blades (27), preferably all of the blades (27), has or have, on the blade root underside (33) thereof facing toward a groove base (35) of the retaining groove (21), a recess (37), the base (59) of which is at least partially obliquely inclined with respect to the groove base (35) of the retaining groove (21) and in which there is arranged in each case a wedge-shaped clamping element (47) for pressing the blade root (31) against the support flanks (23),
   characterized
   in that each recess (37) is provided with a spring element (55), the spring force of which acts along the retaining groove (21) on the respective wedge-shaped clamping element (47),
   in that the recess (37) is delimited by a first side wall (39) and a second side wall (41) located opposite the first side wall (39),
   wherein the spring element (55) is supported on the one hand on the first side wall (39) and on the other hand on an obtuse end (51) of the wedge-shaped clamping element (47), and
   in that provision is made of means with which, for mounting the blade (27) in the retaining groove (21) without prestress, the wedge-shaped clamping element (47) can be displaced temporarily into a position in which the blade root (31) sits in the retaining groove (21) without prestress.
2. Blade ring (44) according to Claim 1,
   in which the spring element (55) is in the form of a disk spring assembly and an opening (57) is provided in the first side wall (39), through both of which a cylindrical pin (53) arranged at the obtuse end (51) of the wedge-shaped clamping element (47) extends.
3. Blade ring (44) according to Claim 1 or 2,
   in which the means comprises a threaded hole (63), which is arranged in the second side wall (41) and into which a mounting screw (65) can be screwed from the outside to displace the wedge-shaped clamping element (47) toward the first side wall (39).
4. Blade ring (44) according to one of Claims 1 to 3,
   in which a plate-like securing element (43) arranged between a blade root underside (33) and a groove base (35) of the retaining groove (21) facing toward the blade root underside (33) secures each of the blades (27) against displacement along the retaining groove (21), in that the ends thereof bear laterally against the blade carrier (46).
5. Blade ring (44) according to one of Claims 1 to 4,
   in which the wedge-shaped clamping element (47) has an at least partially hollow form.
6. Compressor (18) for a stationary gas turbine (10) having at least one blade ring (44) according to one of the preceding claims.

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