Structural assembly for a gas turbine engine

Abstract

A structural subassembly which has a bearing which comprises a statically arranged outer ring and a rotatably arranged inner ring, wherein the inner ring is connected for conjoint rotation to a component that is rotatable about a longitudinal axis or said inner ring forms part of such a component, and wherein the longitudinal axis defines an axial direction of the bearing. The structural subassembly furthermore comprises a housing flange of a support structure, to which flange the statically arranged outer ring is connected. Provision is made for the outer ring to be of two-part design, wherein each part of the outer ring has a connecting element which is connected to the housing flange, wherein the housing flange is arranged between the two connecting elements in the axial direction.

Claims

1. A structural subassembly, which has: a bearing which has a statically arranged outer ring, a rotatably arranged inner ring and a plurality of rolling elements arranged therebetween, wherein the inner ring is at least one chosen from connected for conjoint rotation to a component that is rotatable about a longitudinal axis or is part of the component, wherein the longitudinal axis defines an axial direction of the bearing, a housing flange of a support structure, the statically arranged outer ring being connected to the housing flange, the outer ring including a first part and a second part, the first part including a first connecting element connected to the housing flange and the second part including a second connecting element connected to the housing flange, wherein the housing flange is arranged between the first and second connecting elements in the axial direction; wherein one of the first part and the second part includes an integral axially extending portion having an inner surface engaging the plurality of rolling elements and forming an outer running surface for the plurality of rolling elements.

2. The structural subassembly according to claim 1, wherein the first and second connecting elements are each configured as a flange and are flanged to the housing flange.

3. The structural subassembly according to claim 1, wherein the outer ring is split radially, wherein one of the first part and the second part is a radially inner ring element and the other of the first part and the second part is a radially outer ring element.

4. The structural subassembly according to claim 3, wherein the radially inner ring element forms the outer running surface, the radially outer ring element adjoins the radially inner ring element radially on an outside, and the radially inner and radially outer ring elements have respective axial regions that overlap in the axial direction.

5. The structural subassembly according to claim 4, wherein the first and second connecting elements respectively extend radially outward on axially opposite sides of the outer ring from the respective axial regions.

6. The structural subassembly according to claim 3, wherein the radially outer ring element and the radially inner ring element are connected to one another for conjoint rotation by an interference fit.

7. The structural subassembly according to claim 1, wherein the outer ring is split axially, wherein the outer ring has an axially forward ring element and an axially rearward ring element, the axially forward ring element forming one of the first and second connecting elements and the axially rearward ring element forming the other of the first and second connecting elements.

8. The structural subassembly according to claim 7, wherein one of the axially forward and the axially rearward ring elements includes the running surface of the bearing, and the other of the axially forward and the axially rearward ring elements is connected to the one of the axially forward and the axially rearward ring elements spaced apart at a distance from the running surface.

9. The structural subassembly according to claim 8, wherein the first and second connecting elements respectively extend radially outward on axially opposite sides of the outer ring from axial regions of the axially forward ring element and of the axially rearward ring element.

10. The structural subassembly according to claim 7, and further including a threaded fastener, wherein the axially forward ring element and the axially rearward ring element are connected to one another for conjoint rotation via the threaded fastener.

11. The structural subassembly according to claim 1, wherein a center of mass of the connection between the first and second connecting elements and the housing flange lies in a plane in which a center of mass of the bearing also lies.

12. The structural subassembly according to claim 11, wherein the first part has a first axial width and the second part has a second axial width different from the first axial width, and a radially inner portion of the first part and a radially inner portion of the second part are not symmetrical with one another.

13. The structural subassembly according to claim 1, wherein the inner ring is shrunk onto a planet carrier of a planetary gear box or onto an element connected to the planet carrier.

14. The structural subassembly according to claim 1, wherein the first part has a first axial width and the second part has a second axial width different from the first axial width, and a radially inner portion of the first part and a radially inner portion of the second part are not symmetrical with one another.

15. A gas turbine engine for an aircraft, which has: an engine core which comprises a turbine, a compressor and a core shaft connecting the turbine to the compressor and formed as a hollow shaft; a fan, which is positioned upstream of the engine core, wherein the fan comprises a plurality of fan blades and is driven by a fan shaft; and a planetary gear box, the input of which is connected to the turbine shaft and the output of which is connected to the fan shaft, wherein the planetary gear box comprises a planet carrier which is supported by the structural subassembly according to claim 1 on a support structure of the gas turbine engine.

Description

(1) The invention will be explained in more detail below on the basis of a plurality of exemplary embodiments with reference to the figures of the drawing. In the drawing:

(2) FIG. 1 shows a lateral sectional view of a gas turbine engine;

(3) FIG. 2 shows a close-up lateral sectional view of an upstream portion of a gas turbine engine;

(4) FIG. 3 shows a partially cut-away view of a gear box for a gas turbine engine;

(5) FIG. 4 shows an exemplary embodiment of a structural subassembly which has a bearing having a two-part outer ring, which is connected to a housing flange of a support structure, wherein the outer ring is split radially; and

(6) FIG. 5 shows a further exemplary embodiment of a structural subassembly which has a bearing having a two-part outer ring, which is connected to a housing flange of a support structure, wherein the outer ring is split axially.

(7) FIG. 1 illustrates a gas turbine engine 10 having a main axis of rotation 9. The engine 10 comprises an air intake 12 and a thrust fan 23 that generates two air flows: a core air flow A and a bypass air flow B. The gas turbine engine 10 comprises a core 11 which receives the core air flow A. In the sequence of axial flow, the engine core 11 comprises a low-pressure compressor 14, a high-pressure compressor 15, a combustion device 16, a high-pressure turbine 17, a low-pressure turbine 19, and a core thrust nozzle 20. An engine nacelle 21 surrounds the gas turbine engine 10 and defines a bypass duct 22 and a bypass thrust nozzle 18. The bypass air flow B flows through the bypass duct 22. The fan 23 is attached to and driven by the low-pressure turbine 19 by way of a shaft 26 and an epicyclic gear box 30.

(8) During use, the core air flow A is accelerated and compressed by the low-pressure compressor 14 and directed into the high-pressure compressor 15, where further compression takes place. The compressed air expelled from the high-pressure compressor 15 is directed into the combustion device 16, where it is mixed with fuel and the mixture is combusted. The resulting hot combustion products then propagate through the high-pressure and the low-pressure turbines 17, 19 and thereby drive said turbines, before being expelled through the nozzle 20 to provide a certain propulsive thrust. The high-pressure turbine 17 drives the high-pressure compressor 15 by means of a suitable connecting shaft 27. The fan 23 generally provides the major part of the thrust force. The epicyclic gear box 30 is a reduction gear box.

(9) An exemplary arrangement for a geared fan gas turbine engine 10 is shown in FIG. 2. The low-pressure turbine 19 (see FIG. 1) drives the shaft 26, which is coupled to a sun gear 28 of the epicyclic gear box assembly 30. Multiple planet gears 32, which are coupled to one another by a planet carrier 34, are situated radially to the outside of the sun gear 28 and mesh therewith. The planet carrier 34 limits the planet gears 32 to orbiting around the sun gear 28 in a synchronous manner while enabling each planet gear 32 to rotate about its own axis. The planet carrier 34 is coupled by way of linkages 36 to the fan 23 so as to drive the rotation of the latter about the engine axis 9. Radially to the outside of the planet gears 32 and meshing therewith is an annulus or ring gear 38 that is coupled, via linkages 40, to a stationary support structure 24.

(10) It is noted that the terms “low-pressure turbine” and “low-pressure compressor” as used herein can be taken to mean the lowest pressure turbine stage and the lowest pressure compressor stage (that is to say not including the fan 23) respectively and/or the turbine and compressor stages that are connected to one another by the connecting shaft 26 with the lowest rotational speed in the engine (that is to say not including the gear box output shaft that drives the fan 23). In some documents, the “low-pressure turbine” and the “low-pressure compressor” referred to herein may alternatively be known as the “intermediate-pressure turbine” and “intermediate-pressure compressor”. Where such alternative nomenclature is used, the fan 23 can be referred to as a first compression stage or lowest-pressure compression stage.

(11) The epicyclic gear box 30 is shown in an exemplary manner in greater detail in FIG. 3. Each of the sun gear 28, the planet gears 32 and the ring gear 38 comprise teeth about their periphery to mesh with the other gears. However, for clarity, only exemplary portions of the teeth are illustrated in FIG. 3. Although four planet gears 32 are illustrated, it will be apparent to the person skilled in the art that more or fewer planet gears 32 may be provided within the scope of protection of the claimed invention. Practical applications of an epicyclic gear box 30 generally comprise at least three planet gears 32.

(12) The epicyclic gear box 30 illustrated by way of example in FIGS. 2 and 3 is a planetary gear box, in that the planet carrier 34 is coupled to an output shaft via linkages 36, wherein the ring gear 38 is fixed. However, any other suitable type of epicyclic gear box 30 can be used. By way of further example, the epicyclic gear box 30 can be a star arrangement, in which the planet carrier 34 is held so as to be fixed, wherein the ring gear (or annulus) 38 is allowed to rotate. In the case of such an arrangement, the fan 23 is driven by the ring gear 38. As a further alternative example, the gear box 30 can be a differential gear box in which both the ring gear 38 and the planet carrier 34 are allowed to rotate.

(13) It will be appreciated that the arrangement shown in FIGS. 2 and 3 is by way of example only, and various alternatives are within the scope of protection of the present disclosure. Purely by way of example, any suitable arrangement can be used for positioning the gear box 30 in the engine 10 and/or for connecting the gear box 30 to the engine 10. By way of a further example, the connections (such as the linkages 36, 40 in the example of FIG. 2) between the gear box 30 and other parts of the engine 10 (such as the input shaft 26, the output shaft and the fixed structure 24) may have a certain degree of stiffness or flexibility. By way of a further example, any suitable arrangement of the bearings between rotating and stationary parts of the engine (for example between the input and output shafts of the gear box and the fixed structures, such as the gear box housing) may be used, and the disclosure is not limited to the exemplary arrangement of FIG. 2. For example, where the gear box 30 has a star arrangement (described above), the person skilled in the art would readily understand that the arrangement of output and support linkages and bearing positions would typically be different to that shown by way of example in FIG. 2.

(14) Accordingly, the present disclosure extends to a gas turbine engine having an arbitrary arrangement of gear box types (for example star-shaped or planetary), support structures, input and output shaft arrangement, and bearing positions.

(15) Optionally, the gear box may drive additional and/or alternative components (e.g. the intermediate-pressure compressor and/or a booster compressor).

(16) Other gas turbine engines in which the present disclosure can be used may have alternative configurations. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of connecting shafts. As a further example, the gas turbine engine shown in FIG. 1 has a split flow nozzle 20, 22, which means that the flow through the bypass duct 22 has a dedicated nozzle, which is separate from the engine core nozzle 20 and is radially on the outside with respect to the latter. However, this is not restrictive, and any aspect of the present disclosure can also apply to engines in which the flow through the bypass duct 22 and the flow through the core 11 are mixed or combined before (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. One or both nozzles (whether mixed or split flow) can have a fixed or variable area. Although the example described relates to a turbofan engine, the disclosure can be applied, for example, to any type of gas turbine engine, such as, for example, an open rotor engine (in which the fan stage is not surrounded by an engine nacelle) or a turboprop engine. In some arrangements, the gas turbine engine 10 may not comprise a gear box 30.

(17) The geometry of the gas turbine engine 10, and components thereof, is/are defined by a conventional axis system, comprising an axial direction (which is aligned with the axis of rotation 9), a radial direction (in the bottom-to-top direction in FIG. 1), and a circumferential direction (perpendicular to the view in FIG. 1). The axial, radial and circumferential directions run so as to be mutually perpendicular.

(18) It can be seen in FIG. 2 that the planet carrier 34 is supported on a bearing 5. The bearing 5 has an outer ring, which is supported on a strut or wall structure 45 that is part of a load-bearing support structure of the gas turbine engine. In the context of the present invention, the configuration of the bearing 5 is important. It should be noted here that the following description of the bearing 5 is not restricted to its use in a gas turbine engine in connection with the support of a planetary gear box. In principle, the bearing 5 can be used in any context.

(19) According to the exemplary embodiment in FIG. 4, the bearing 5 comprises a rotating inner ring 8 connected to a rotatable component, a static outer ring 6 and rolling elements 7, which are arranged in between and are designed, for example, as balls or rollers. However, this configuration of the bearing 5 should be understood as being merely by way of example.

(20) The outer ring 6 of the bearing 5 is connected to a support structure 45, which is part of a load-bearing support structure, e.g. of a gas turbine engine. The support structure 45 can be a fixing arm, a strut, a wall or a housing element, for example. For connection of the bearing 5 to the support structure 45, the support structure forms a flange 450, the lateral surfaces of which extend in the radial direction. The flange 450 is referred to below as the housing flange, although, as explained, it is not necessarily part of a housing but of a support structure in general.

(21) The outer ring 6 is of two-part design and comprises a radially inner ring element 61 and a radially outer ring element 62. The radially inner ring element 61 has an axial region 611 and a connecting element 612, which projects perpendicularly from the axial region 611. The radially outer ring element 62 likewise has an axial region 621 and a connecting element 622, which projects perpendicularly from the axial region 621.

(22) With its inner surface, the axial region 611 of the radially inner ring element 61 forms a running surface of the bearing 5. The axial region 621 of the radially outer ring element 62 adjoins the axial region 611 radially on the outside. In this arrangement, provision can be made for axial region 611 and axial region 621 of the two ring elements 61, 62 to be connected to one another for conjoint rotation by an interference fit. As an alternative, a connection for conjoint rotation can be provided by way of positive-locking elements (not illustrated), or a connection is established only indirectly, via the connection of the connecting elements 621, 622 to the housing flange.

(23) The two connecting elements 612, 622 of the two ring elements 61, 62 extend radially outward on axially opposite sides of the outer ring 6. They each form a flange, which is connected to the housing flange 450 by means of bolts 91. Thus, provision is made for the connecting elements 612, 622 to be arranged on both sides of the housing flange 450, and hence for the housing flange 450 to be arranged between the two connecting elements 612, 622 in the axial direction. This ensures that there is uniform load transfer from the bearing 5 to the housing flange 450 and the support structure 45 without bending moments being introduced into the support structure 45.

(24) It is envisaged here that both the center of mass of the connection of the two connecting elements 612, 622 to the housing flange 450 and the center of mass of the bearing 5 lie in the same plane E. Here, the plane E is perpendicular to the axial direction of the bearing 5, which is defined by the axis of rotation of a rotating element to which the inner ring 8 is connected. By arranging both centers of mass in the same plane, the introduction of bending moments or tilting moments into the support structure 45 is avoided. On the other hand, there is such introduction of bending moments if only one connecting element is provided and this is flanged to the housing flange 450 on one side.

(25) FIG. 5 shows an exemplary embodiment of a bearing which differs from the exemplary embodiment in FIG. 4 in that the outer ring 6 is split axially and not split radially as in the exemplary embodiment in FIG. 4.

(26) According to the exemplary embodiment in FIG. 5, the bearing 5 once again comprises a rotating inner ring 8 connected to a rotatable component, a static outer ring 6 and rolling elements 7, which are arranged in between. The bearing 5 is connected to a support structure 45, which is part of a load-bearing support structure, e.g. of a gas turbine engine. For connection of the outer ring 6 of the bearing 5 to the support structure 45, the support structure forms a housing flange 450, the lateral surfaces of which extend in the radial direction.

(27) The outer ring 6 is of two-part design and comprises an axially forward ring element 63 and an axially rearward ring element 64. The axially forward ring element 63 comprises an axial region 631 and a connecting element 632, which projects perpendicularly from the axial region 631. The axially rearward ring element 64 likewise has an axial region 641 and a connecting element 642, which projects perpendicularly from the axial region 641.

(28) On its inner side, the axial region 641 of the axially rearward ring element 64 forms a running surface of the bearing 5. The axially forward ring element 63 is situated axially ahead of the ring element 64. The two ring elements 63, 64 are connected to one another by means of bolts 92.

(29) The two connecting elements 632, 642 of the two ring elements 63, 64 extend on axially opposite sides of the outer ring 6. As in the exemplary embodiment in FIG. 4, they each form a flange that is connected to the housing flange 450 by means of bolts 91, which are illustrated only schematically. The housing flange 450 is thus arranged between the two connecting elements 632, 642 in the axial direction, and therefore there is uniform load transfer from the bearing 5 to the housing flange 450 and the support structure 45, which is substantially free of bending moments. As in the exemplary embodiment in FIG. 4, provision can be made here for the center of mass of the connection of the two connecting elements 632, 642 to the housing flange 450 and the center of mass of the bearing 5 to lie in the same plane E.

(30) It will be understood that the invention is not limited to the embodiments described above, and various modifications and improvements can be made without departing from the concepts described herein. For example, the bearing can be designed as a sliding bearing instead of a rolling bearing.

(31) It should be noted that, except where mutually exclusive, any of the features described can be employed separately or in combination with any other features, and the disclosure extends to and includes all combinations and sub-combinations of one or more features that are described herein. If ranges are defined, said ranges thus comprise all of the values within said ranges as well as all of the partial ranges that lie in a range.