ROTOR WITH OVERHANG AT BLADES FOR A LOCKING ELEMENT

Abstract

A rotor for an engine is provided. The rotor comprising a rotor base part that has fastening grooves for rotor blades that are arranged in succession around a rotational axis along a circumferential direction, multiple rotor blades that are respectively supported in a form-fit manner inside a corresponding fastening groove by means of a blade root, and at least one securing element for the axial securing—with respect to a rotational axis—of at least one of the rotor blades at the rotor base part. The at least one securing element has two edges that are arranged at a radial distance to one another and through which the securing element is supported in a form-fit manner at the rotor base part, on the one hand, and, on the other hand, at the at least one rotor blade.

Claims

1. A rotor for an engine, comprising a rotor base part that has fastening grooves for rotor blades that are arranged in succession around a rotational axis along a circumferential direction, multiple rotor blades that are respectively supported in a form-fit manner inside a corresponding fastening groove by means of a blade root, and at least one securing element for the axial securing—with respect to a rotational axis—of at least one of the rotor blades at the rotor base part, wherein the at least one securing element has two edges that are arranged at a radial distance to one another and through which the securing element is supported in a form-fit manner at the rotor base part, on the one hand, and, on the other hand, at the at least one rotor blade, and wherein, for the purpose of providing a form-fit connection with the rotor blade, the one edge of the securing element is surrounded by the projection of the rotor blade in at least one area, which for this purpose extends radially inward beyond the one edge of the securing element with respect to the rotational axis and along the circumferential direction, wherein along its extension in the circumferential direction, the projection has at least one edge section that surrounds the edge of the securing element, with the edge section being recessed at a radially inner lower edge of the projection with respect to at least one further edge section of the projection that also surrounds the edge of the securing element in the radially outwardly oriented direction.

2. The rotor according to claim 1, wherein the at least one radially outwardly recessed edge section has a smaller extension in the radially inwardly oriented direction.

3. The rotor according to claim 1, wherein the at least one radially outwardly recessed edge section is provided at an end of the projection that is positioned in the circumferential direction.

4. The rotor according to claim 1, wherein the at least one radially outwardly recessed edge section forms an area at the radially inner lower edge that extends in a manner at least partially tilted with respect to the circumferential direction.

5. The rotor according to claim 1, wherein the at least one radially outwardly recessed edge section with a length along the circumferential direction that corresponds to at least three times a height by which the radially outwardly recessed edge section is maximally recessed with respect to an adjoining edge section of the projection.

6. The rotor according to claim 1, wherein the at least one radially outwardly recessed edge section is recessed with respect to an adjoining edge section of the projection by at least a height of 0.5 mm, in particular by at least a height of 0.8 mm or 1 mm.

7. The rotor according to claim 1, wherein the projection has two, namely first and second, edge sections that are respectively recessed in the radially outwardly oriented direction with respect to at least one further, third edge section of the projection that also surroundings the edge of the securing element.

8. The rotor according to claim 7, wherein the two recessed edge sections are recessed to a different extent and/or extend along the circumferential direction with differing lengths.

9. The rotor according to claim 7, wherein the first and second radially outwardly recessed edge sections are provided at ends of the projection that are arranged at a distance from each other along the circumferential direction.

10. The rotor according to claim 7, wherein one of first and second radially outwardly recessed edge sections is recessed with respect to the adjoining third edge section of the projection by at least a sum of the predefined shape and positional tolerances of this third edge section, wherein a nominal position of the third edge section with respect to the corresponding fastening groove and/or with respect to a projection of a neighboring rotor blade of the rotor is predefined based on shape and positional tolerances.

11. The rotor according to claim 1, wherein projections with edge sections which are adjacent to each other and that are respectively recessed radially outward are provided at at least two rotor blades of the rotor arranged adjacent to each other along the circumferential direction, so that a radially outwardly oriented recess of a defined minimum length and minimum height is formed in the area of the adjacent edge sections of the two neighboring rotor blades.

12. The rotor according to claim 11, wherein the recess is elliptical, trapezoid or triangular as viewed along the rotational axis.

13. The rotor according to claim 11, wherein projections with edge sections that are adjacent to each other and are respectively recessed radially outward are provided along the circumferential direction at each pair of rotor blades arranged adjacent to each other, so that respectively one radially outwardly oriented recess of a defined minimum length and minimum height is formed along the circumferential direction in the area of adjacent edge sections of two neighboring rotor blades.

14. The rotor according to claim 1, wherein the at least one radially outwardly recessed edge section is created by means of mechanical material removal.

15. The rotor according to claim 1, wherein the at least one radially outwardly recessed edge section is created by means of thermal material removal.

16. The rotor according to claim 1, wherein the at least one securing element is provided for the axial securing of at least two rotor blades, and in that the one edge the securing element is thus surrounded by the projections of at least two rotor blades.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The attached Figures illustrate possible embodiment variants of the invention in an exemplary manner.

[0030] FIG. 1A shows, in sections, a rotor that is designed according to the invention, with a view along a rotational axis of the rotor of two projections of two neighboring rotor blades of the rotor that are radially outwardly recessed in certain sections.

[0031] FIG. 1B shows, in a view that corresponds to the one of FIG. 1A, a radial offset between two blade bases of the neighboring rotor blades with respect to the nominal orientation of the two rotor blades to each other as shown in FIG. 1A.

[0032] FIG. 1C shows, in a view that corresponds to the one of FIG. 1A, the rotor, with a securing element being partially omitted for the purpose of illustrating a blade neck of a rotor blade that is inserted into a fastening groove.

[0033] FIG. 1D shows a rotor blade as a detail drawing.

[0034] FIG. 2A shows, in a view that corresponds to the ones of FIGS. 1A and 1B, another embodiment variant with recessed edge sections having different geometrical designs at two projections of two rotor blades.

[0035] FIG. 2B shows, in a view that corresponds to the one of FIG. 1C, the rotor of FIG. 2A.

[0036] FIG. 3 shows a sectional rendering along the rotational axis of a rotor that is embodied according to the invention in the installed state inside a gas turbine engine.

[0037] FIG. 4 shows, in sections, a sectional rendering of the rotor that is obtained along a section line that is parallel to the rotational axis of the rotor.

[0038] FIGS. 5A-5D show, respectively in sections, a rotor as it is known from the state of the art with two neighboring rotor blades, with their projections being shown with a linear edge and thus with lower edges that are nominally aligned with each other (FIG. 5A), as well as lower edges (FIGS. 5B and 5C) that may be offset with respect to one another due to tolerances, and with a securing element (FIG. 5D) being partially omitted.

[0039] FIG. 6 schematically shows a sectional rendering of a gas turbine engine in which a rotor according to the invention is used.

DETAILED DESCRIPTION

[0040] FIG. 6 schematically illustrates, in a sectional rendering, a (gas turbine) engine T in which the individual engine components are arranged in succession along a central axis or a rotational axis M. By means of a fan F, air is suctioned in along an entry direction E at an inlet or an intake E of the engine T. This fan F is driven by a shaft that is set into rotation by a turbine TT. Here, the turbine TT connects to a compressor V, which for example has a low-pressure compressor 11 and a high-pressure compressor 12, and where necessary also a medium-pressure compressor. The fan F supplies air to the compressor V, on the one hand, and, on the other hand, to a bypass channel B for generating a thrust. The air that is conveyed via the compressor V is eventually transported inside the combustion chamber section BK where the driving power for driving the turbine TT is generated. For this purpose, the turbine TT has a high-pressure turbine 13, a medium-pressure turbine 14, and a low-pressure turbine 15. The turbine TT drives the fan F by means of the energy that is released during combustion in order to then generate the necessary thrust by means of the air that is conveyed into the bypass channel B. The air is discharged from the bypass channel B in the area of an outlet A at the end of the engine T where the exhaust gases flow out of the turbine TT in the outward direction, with the outlet A usually having a thrust nozzle.

[0041] In particular in the area of the high-pressure turbine 13, at least one rotor with the configuration as it has been described in the introduction in connection with FIGS. 5A to 5D is used. Here, the rotor is arranged and mounted so as to be rotatable about the central axis or rotational axis M, namely in such a manner that the individual securing plates 4 that are provided along the circumferential direction U for the axial securing of the rotor blades 3a, 3b are arranged at the downstream front side of the rotor 2. The individual securing elements 4 are thus facing towards an annular space 5 that is formed in the area of the blade roots 32 of the individual rotor blades 3a, 3b between the rotor and a guide vane arrangement 6. As has been described above, in a configuration of the projections 310 of the blade bases 31 used for providing the connection between the rotor blades 3a, 3b and a securing element 4, the flow that is created inside this annular space 5 can be subject to undesirable turbulences if individual projections 310 are arranged in a manner offset with respect to one another due to tolerances. In that case, individual projections 31 completely protrude into the flow channel which is defined in a circular manner about the rotational axis along the securing plates 4, or they are radially outwardly offset with respect to the same (cf. FIGS. 5B and 5C).

[0042] Here, an improvement can be achieved with the solution according to the invention. According to it, a projection 310 that is provided for the form-fit connection to a radially outer edge 43 of a multi-part or single-part securing element, such as a securing plate 4, is formed with an edge section of a defined geometry and size that is recessed in the radially outer direction ra. Thus, with the solution according to the invention, it can be excluded that a linear or circular-arc-shaped course of the lower edges of the projections 310 arranged in succession along the circumferential direction U and located radially inside is present at each pair of neighboring rotor blades 3a, 3b, even in a nominal arrangement of the individual rotor blades 3a, 3b with respect to one another. Rather, at least one defined radial recess is provided from the outset, influencing the flow as little as possible, but in any case doing so in a predictable manner. Preferably, multiple recesses that are distributed along the circumferential direction U are provided, in particular at every pair of blade bases 31 that are arranged adjacent to each other.

[0043] For example, in the embodiment variant of FIGS. 1A to 1C, a projection 310 of a blade base 31 of each rotor blade 3a, 3b that is fixated at the rotor base part 2 has two radially outwardly recessed edge sections 311a and 311c. These two radially recessed edge sections 311a and 311c have a smaller extension in the radially inwardly oriented direction ri than a third edge section 311b that is formed in between them. Here, the length of the third edge section 311b along the circumferential direction U can be at least twice the shape and positional tolerances of a gap between the axial securing elements 4, and/or at least half the minimum width d of a blade neck 320 of the blade root 32 of a rotor blade 3a or 3b that is inserted into the corresponding fastening groove 20 (cf. the detail drawing of a rotor blade 3a of FIG. 1D). Here, the length of the third edge section 311b along the circumferential direction U is less than 60%, where applicable less than 50%, or even less than 35% of the total length L of a projection 310 along the circumferential direction U.

[0044] Respectively one recessed edge section 311a or 311c is provided at the ends of a projection 310 that are positioned at a distance from each other along the circumferential direction U. Here, the edge sections 311a and 311c extend in the circumferential direction U with different lengths a1 and a2. Both recessed edge sections 311a and 311c further form an area of the lower edge of the projection 310 that extends in a tilted manner with respect to the circumferential direction U. Here, each recessed edge section 311a, 311c extends starting from the middle third edge section 311b and obliquely outward towards the respective end, so that a radial extension of the respective recessed edge section 311a or 311c constantly decreases towards the respective lateral edge of the projection 310.

[0045] Here, the individual edge sections 311a and 311c are recessed respectively up to a height b1 or b2 with respect to the middle edge section 311b. In the present case, this height b1 or b2 is more than 0.8 mm, amounting to approximately 1 mm. The extension in the circumferential direction U of the respective recessed edge section 311a, 311c is in turn calculated as a—preferably integral—multiple of this height b1 or b2. In the present case, the length a1, a2 corresponds to at least three times the height b1 or b2 of the respective recessed edge section 311a, 311c.

[0046] The heights b1 and b2 of the recessed edge sections 311a and 311c are dimensioned in such a manner that, in the area of adjacent rotor blades 3a, 3b and thus of adjacent blade bases 31, respectively one radial recess 33 is formed in the course of the lower edges of multiple securing plates 4 that are successive in the circumferential direction U, namely by two recessed edge sections 311c and 311a extending obliquely towards one another. This radial recess 33 is dimensioned in such a manner through the recessed edge sections 311c and 311a of the individual rotor blades 3a and 3b that, also with a maximum radial offset g of two rotor blades 3a and 3b due to tolerances, a radial depth of the respective recess 33 is larger than the offset g, and preferably corresponds to four times the offset g. In this manner, any (relevant) impact on the flow due to the offset g is either excluded or is minimal (cf. FIG. 1B).

[0047] Of course, a sufficient extension of the projection 310 in the radially inner direction ri is still provided by the recessed edge sections 311a and 311c, so that a groove 3100 is present for the surrounded radially outer edge 43 of the securing plate 4 also in the area of a recessed edge section 311a or 311c. The radially inner edge 42 of a securing plate 4 is received inside a groove 2100 of the rotor base part 2 that is formed by a projection 210 that protrudes in the radially outer direction ra. In this way, it is ensured through the securing plate 4 that the individual rotor blades 3a, 3b are axially secured at the rotor base part 2 (cf. also FIG. 3) in the area of their respective blade root 32 which is at least partially covered by a securing plate 4.

[0048] In contrast to the solution known from the state of the art as it is shown in FIGS. 5A to 5D (cf. in particular FIG. 5D), it is further achieved through the recessed edge sections 311a and 311c that, with the edge section 311b being positioned intermediately along the circumferential direction U, the projection 310 extends further radially inward only in that area in which the fastening groove 20 is located. In this way, the edge section 311b projecting further radially inward is dimensioned in such a manner that the blade root 32 can be pushed in the axial direction through the fastening groove 20 and the gap that is thus defined between two webs 22 of the rotor base part 2 if the securing plate 4 is either not yet or no longer attached. This is not possible with a projection of a constant radial extension according to FIG. 5D. Here, the passing of the blade root 32 through a fastening groove 20 is blocked by the projection 310. The projection 310 cannot be pushed beyond the facing webs 22 of the rotor base part 2 that laterally delimit a fastening groove 20. In order to allow for a complete axial movability through the fastening groove 30, the radial extension of the blade root 32 and thus the length of a blade neck 320 would have to be increased in this case, so that a lower edge of the projection 310 extends further radially outside than the ends of the webs 22 throughout. However, this would be accompanied by an increase in the weight of a rotor blade 3a, 3b. In contrast to that, in the shown embodiment variant of a solution according to the invention, the additional mounting advantage can be realized without any disadvantage with respect to the weight.

[0049] In the variant that is illustrated in FIGS. 2A and 2B, the shape of the recessed edge sections 311a and 311c is varied with respect to the variant of FIGS. 1A to 1C. Here, a projection 310 at a blade base 31 is embodied in a profiled manner, so that the two edge sections 311a and 311b of a rotor blade 3a or 3b that are arranged at a distance from each other along the circumferential direction U are embodied so as to be radially backset in the radially outer direction ra with respect to the middle third edge section 311b of the projection 310 of the respective rotor blade 3a or 3b. At that, the individual recessed edge sections 311a and 311c respectively have areas with a constant radial extension along the circumferential direction U. In other words, each of the recessed edge sections 311a, 311c of a rotor blade of FIGS. 2A and 2B has at least one area where a height of the respective recessed edge section 311a, 311c does not decrease in the circumferential direction U or opposite to the same.

[0050] In particular, it is achieved in this manner that a recess 33 defined in the area of the blade bases 31 of two neighboring rotor blades 3a, 3b is trapezoid as viewed along the rotational axis of FIG. 2, while the recess 33 in the variant of FIGS. 1A to 1C is triangular. If the lower edges of the recessed edge sections 311a, 311c extend in a more rounded manner, an elliptical recess can also be formed in a possible further development.

[0051] A cutting manufacturing method or thermal material removal can be provided for manufacturing the recessed edge sections 311a, 311c at a rotor blade 3a or 3b. Thus, in the embodiment variant of FIGS. 1A to 1C, the recessed edge sections 311a and 311c can be manufactured in a comparatively simple manner by means of sanding, for example. A profiled embodiment according to the variant of FIGS. 2A and 2B can for example be manufactured by means of erosion. Here, the manufacture of the recessed edge sections 311a and 311c can be performed at the rotor blades 3a, 3b in one work step with damper pockets (not shown here) or other functional areas, which are usually also manufactured by means of erosion.

[0052] Based on FIG. 2B it is also illustrated in correspondence with FIG. 1C that, also in this embodiment variant, the blade root 32 can be pushed through a fastening groove 20 in the axial direction without being blocked by the projection 31 thanks to the recessed edge sections 311a and 311c, with the securing plate being partially omitted in the rendering. The (middle) edge section 311b that projects further radially inward is dimensioned in such a manner that is fits through the gap defined between two webs 22 of the rotor base part 2 at the upper end of the fastening groove 20.

[0053] Based on the sectional rendering of a longitudinal section according to FIG. 4, the design of the securing plate 4 is illustrated separately. The securing plate 4 has a central area 40 that is located between the radially inner and radially outer edges 42 and 43. It can in particular be seen from FIG. 4 how a radially outer edge 43 of the securing plate 4 is received inside the groove 3100 of the blade base 31 of a rotor blade 3b, and is surrounded by the projection 310 that extends radially inward, while the central area 40 extends outside of the groove 3100 along the blade root 32.

PARTS LIST

[0054] T gas turbine engine [0055] 11 low-pressure compressor [0056] 12 high-pressure compressor [0057] 13 high-pressure turbine [0058] 14 medium-pressure turbine [0059] 15 low-pressure turbine [0060] 2 rotor base part [0061] 20 fastening groove [0062] 210 projection [0063] 2100 groove [0064] 22 web [0065] 30 blade leaf [0066] 31 blade base [0067] 310 projection [0068] 3100 groove [0069] 311 edge [0070] 311a, 311b, 311c edge section [0071] 32 blade root [0072] 320 blade neck [0073] 33 radial recess [0074] 3a, 3b rotor blade [0075] 4 securing plate (securing element) [0076] 40 central area [0077] 42 inner edge [0078] 43 outer edge [0079] 5 annular gap [0080] 6 guide vane arrangement [0081] A outlet [0082] a1, a2 length [0083] B bypass channel [0084] BK combustion chamber section [0085] b1, b2 height [0086] c width [0087] d minimal width of the blade neck [0088] E inlet/intake [0089] F fan [0090] g offset [0091] L total length [0092] M central axis/rotational axis [0093] R entry direction [0094] ra, ri radial direction [0095] TT turbine [0096] U circumferential direction [0097] V compressor