DEVICE, PLANETARY GEAR WITH A DEVICE AND METHOD FOR CREATING A TORQUE-PROOF CONNECTION BETWEEN TWO STRUCTURAL COMPONENTS

Abstract

A device includes two components which are rotationally fixedly operatively connected to one another. One component engages certain regions radially around the other component in an axial direction. Between the components, there is a substantially ring-shaped structural unit by which the rotationally fixed connection is produced. The structural unit includes two elements which extend in a circumferential direction radially between the components. Via the structural unit, there is an interference fit between the radially outer component and the structural unit and between the radially inner component and the structural unit over the entire operating range of the device. The elements bear against one another in the region of their end sides facing toward one another. The coefficient of thermal expansion or the coefficients of thermal expansion of the elements is or are greater than the coefficient of thermal expansion or the coefficients of thermal expansion of the components.

Claims

1. A device having at least two components which are rotationally fixedly operatively connected to one another, wherein one component engages at least in certain regions radially around the other component in an axial direction of the components, and, between the components, there is provided a substantially ring-shaped structural unit by means of which the rotationally fixed connection between the components is produced, characterized in that the structural unit comprises at least two elements which extend in a circumferential direction radially between the components, wherein, by means of the structural unit, there is an interference fit between the radially outer component and the structural unit and between the radially inner component and the structural unit over the entire operating range of the device, and wherein the elements bear against one another in the region of their circumferential end sides or radial end sides facing toward one another, and the coefficient of thermal expansion or the coefficients of thermal expansion of the elements is or are greater than the coefficient of thermal expansion or the coefficients of thermal expansion of the components.

2. The device according to claim 1, wherein a ratio between the coefficients of thermal expansion of the components and of the elements lies in a value range between 0.1 and 0.9.

3. The device according to claim 1, wherein the circumferential end sides of the elements enclose in each case an angle between 0 and 90, preferably between 10 and 80, with a radial outer side and with a radial inner side of the structural unit.

4. The device according to claim 3, wherein the angle between the radial outer side of one of the elements and a circumferential end side of the element is equal to the angle between the radial inner side of the element and the end side.

5. The device according to claim 3, wherein the angle between the radial outer side of one of the elements and the circumferential end side of the element differs from the angle between the radial inner side of the element and the end side.

6. The device according to claim 3, wherein the angles between the circumferential end sides of the elements and the radial outer sides and between the circumferential end sides and the radial inner sides are equal.

7. The device according to claim 3, wherein the angles between the circumferential end sides of the elements and the radial outer sides and between the circumferential end sides and the radial inner sides differ from one another.

8. The device according to claim 1, wherein the structural unit comprises more than two elements, which elements bear against one another in each case in the region of end sides which face toward one another and which delimit the elements in the circumferential direction of the components or in the radial direction of the structural unit.

9. The device according to claim 1, wherein the circumferential end sides of the elements, at least in certain regions in the radial extent direction of the elements between the radial inner side and the radial outer side, have an arcuate profile at least in certain regions.

10. The device according to claim 1, wherein the elements of the structural unit, in the region of their radial outer sides and/or in the region of their radial inner sides, which in each case constitute radial end sides of the elements, have a wedge-shaped cross-sectional profile in the axial direction.

11. The device according to claim 1, wherein one of the components is a planet carrier of a planetary gear box and the other component, connected rotationally fixedly thereto, is a bolt on which planet gears of the planetary gear box can be arranged in a rotatable manner and which is arranged in a bore of the planet carrier, wherein the ring-shaped structural unit is arranged radially between the planet carrier and the bolt.

12. A planetary gear box having a device according to claim 1.

13. A method for producing a rotationally fixed connection between two components, having the following method steps: introducing the first component in an axial direction of the components into a bore of the second component; installing a ring-shaped structural unit according to claim 1 in the axial direction of the components into the bore of the second component, wherein the ring-shaped structural unit is introduced before the first component, after the first component, or at the same time as the first component, into the bore of the second component.

14. The method according to claim 13, wherein the component temperature of the second component is raised in relation to an ambient temperature before the introduction of the first component and of the structural unit into the bore, and/or the component temperature of the structural unit and/or the component temperature of the first component is lowered in relation to the ambient temperature.

15. A gas turbine engine for an aircraft, said gas turbine engine comprising the following: an engine core which comprises a turbine, a compressor, and a core shaft that connects the turbine to the compressor; a fan which is positioned upstream of the engine core, and a planetary gear box which receives an input from the core shaft and outputs drive for the fan so as to drive the fan at a lower rotational speed than the core shaft, wherein the planetary gear box is designed according to claim 12.

16. The gas turbine engine according to claim 15, wherein the turbine is a first turbine, the compressor is a first compressor, and the core shaft is a first core shaft; the engine core furthermore comprises a second turbine, a second compressor and a second core shaft which connects the second turbine to the second compressor; and the second turbine, the second compressor and the second core shaft are arranged so as to rotate at a higher rotational speed than the first core shaft.

Description

[0068] In the figures:

[0069] FIG. 1 shows a longitudinal sectional view of a gas turbine engine having a planetary gear box;

[0070] FIG. 2 shows an enlarged partial longitudinal sectional view of an upstream portion of a gas turbine engine;

[0071] FIG. 3 shows a planetary gear box for a gas turbine engine in a standalone view;

[0072] FIG. 4 shows a schematic detail illustration of a device having a ring-shaped structural unit, which is installed between a planet carrier of the planetary gear box according to FIG. 3 and a bolt which is arranged in a bore of the planet carrier;

[0073] FIG. 5 shows a schematic detail view of an element of the ring-shaped structural unit as per FIG. 4;

[0074] FIG. 6 shows a schematic sectional view of a further embodiment of the planetary gear box along a section line VI-VI denoted in more detail in FIG. 3;

[0075] FIG. 7 shows a simplified side view of the ring-shaped structural unit as per FIG. 6; and

[0076] FIG. 8 shows a simplified partial illustration of a further embodiment of the device according to the present disclosure.

[0077] FIG. 1 illustrates a gas turbine engine 10 with a main axis of rotation 9. The engine 10 comprises an air intake 12 and a thrust fan 23 that generates two airflows: a core airflow A and a bypass airflow B. The gas turbine engine 10 comprises an engine core 11 that receives the core airflow 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 airflow B flows through the bypass duct 22. The fan 23 is attached to the low-pressure turbine 19 via a shaft 26 and a planetary gear box 30 or an epicyclic gear box, and is driven by said low-pressure turbine 19. The shaft 26 herein is also referred to as the core shaft.

[0078] During use, the core airflow 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 resultant hot combustion products then expand through, and thereby drive, the high-pressure and low-pressure turbines 17, 19 before being discharged through the core thrust nozzle 20 in order to provide a certain thrust force. The high-pressure turbine 17 drives the high-pressure compressor 15 by way of a suitable connecting shaft 27, which is also referred to as the core shaft. The fan 23 generally provides the majority of the propulsion force. The planetary gear box 30 is a reduction gear box.

[0079] An exemplary arrangement for a geared fan gas turbine engine 10 is shown in FIG. 2. The low-pressure turbine 19 drives the shaft 26 which is coupled to a sun gear 28 of the planetary gear box 30. Multiple planet gears 32A to 32D, which are illustrated in more detail in FIG. 3 and which are coupled to one another by means of a planet carrier 34, are situated radially outside the sun gear 28 and mesh with the latter, and are in each case arranged so as to be rotatable on carrier elements 29 which are connected in a rotationally fixed manner to the planet carrier 34. The planet carrier 34 restricts the planet gears 32A to 32D to orbiting in a synchronized manner about the sun gear 28, while said planet carrier 34 enables each planetary gear 32A to 32D to rotate about its own axis on the carrier elements 29. 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. An external gear or ring gear 38, which is coupled by means of linkages 40 to a static, rotationally fixed support structure 24, is situated radially to the outside of the planet gears 32A to 32D and meshes therewith.

[0080] 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.

[0081] The planetary gear box 30 is shown in more detail in an exemplary manner in FIG. 3. The sun gear 28, the planet gears 32A to 32D and the ring gear 38 each comprise teeth around the periphery thereof for the purposes of meshing with the other toothed gears. Although four planet gears 32A to 32D are illustrated, it will be apparent to the person skilled in the art that more or fewer than four planet gears can be provided within the scope of protection of the claimed invention. Practical applications of a planetary gear box 30 generally comprise at least three planet gears.

[0082] The epicyclic gear box 30 illustrated by way of example in FIGS. 2 and 3 is a planetary gear box in which the planet carrier 34 is coupled by means of linkages 36 to an output shaft, wherein the ring gear 38 is fixed to the housing. However, any other suitable type of epicyclic gear box 30 can be used. As a further example, the epicyclic gear box 30 can have a star arrangement in which the planet carrier 34 is held rotationally fixed and the ring gear 38 is rotatable. 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.

[0083] It will be appreciated that the arrangement shown in FIGS. 2 and 3 is merely exemplary, and various alternatives fall within the scope of protection of the present disclosure. Purely by way of example, any suitable arrangement can be used for positioning the planetary gear box 30 in the gas turbine engine 10 and/or for connecting the planetary gear box 30 to the gas turbine engine 10. By way of further example, the connections (for example the linkages 36, 40 in the example of FIG. 2) between the planetary gear box 30 and other parts of the engine 10 (such as, for example, the input shaft 26, the output shaft, and the fixed structure 24) can have a certain degree of stiffness or flexibility. By way of 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 planetary gear box and the fixed structures, such as, for example, the gear box casing) can be used, and the disclosure is not limited to the exemplary arrangement of FIG. 2. For example, where the planetary gear box 30 has a star arrangement (described above), the skilled person would readily understand that the arrangement of output and support linkages and bearing positions would generally be different to those shown in an exemplary manner in FIG. 2.

[0084] 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.

[0085] Optionally, the gear box can drive additional and/or alternative components (for example the intermediate-pressure compressor and/or a booster compressor).

[0086] Other gas turbine engines in which the present disclosure can be used can 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. By way of further example, the gas turbine engine shown in FIG. 1 has a split flow nozzle 20, 22, meaning that the flow through the bypass duct 22 has a dedicated nozzle that is separate from and radially outside the engine core nozzle 20. 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 can be referred to as a mixed flow nozzle. One or both nozzles (whether mixed or split flow) can have a fixed or variable region. 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.

[0087] The geometry of the gas turbine engine 10, and components thereof, is or are defined using a conventional axis system which comprises an axial direction (which is aligned with the axis of rotation 9), a radial direction (in the direction from bottom to top 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.

[0088] FIG. 4 shows an enlarged view of a region IV denoted in more detail in FIG. 3, which region constitutes a region of a device 60 of the planetary gear box 30. The device 60 comprises the planet carrier 34 and the carrier elements 29 which are connected rotationally fixedly to said planet carrier and which are designed as bolts. The carrier element 29 illustrated in FIG. 4 is arranged with a cylindrical region in a bore 42 of the planet carrier 34. Between an outer side 43 of the carrier element 29 and an inner side 44 of the bore 42, there is installed a substantially ring-shaped structural unit 45, by means of which the rotationally fixed connection between the planet carrier 34 and the carrier element 29 is produced. Here, the planet carrier 34 engages in certain regions radially around the component, or the carrier element 29, in an axial direction X of the planet carrier 34 and of the carrier element 29.

[0089] The ring-shaped structural unit 45 comprises multiple elements 46, which extend in a circumferential direction U of the planetary gear box 30 radially between the carrier element 29 and the planet carrier 34. Here, the inner diameter of the bore 42 of the planet carrier 34 and the outer diameter of the outer side 43 of the carrier element 29 are adapted to the outer diameter of the structural unit 45 and to the inner diameter of the structural unit 45 respectively, such that an interference fit is present in each case between the radially inner carrier element 29 and the structural unit 45 and between the radially outer planet carrier 34 and the structural unit 45 over the entire operating range of the planetary gear box 30, by means of which interference fit the rotationally fixed operative connection between the carrier element 29 and the planet carrier 34 is ensured.

[0090] In the exemplary embodiment of the planetary gear box 30 illustrated in FIG. 4, the elements 46 to 48 bear against one another in the region of mutually facing circumferential end sides 46A and 47A, and 46B and 48B, respectively. The end sides 46A to 48B of the elements 46 to 48 enclose in each case an angle , with an outer side 49, or radial end side, respectively, of the structural unit 45. Furthermore, the end sides 46A to 48B enclose in each case an angle , with an inner side 50 or radial end side of the structural unit 45. In other words, the end sides 46A to 48B enclose the angles , , , in each case with the tangent to the outer side 49 or to the inner side 50. As an alternative to this, it is also possible for the inclination of the wedge-shaped ends of the elements 46 to 48 to be defined in a manner dependent on the angle between the end sides 46A to 48B and the radial extent direction R of the structural unit 45.

[0091] The ring-shaped structural unit 45, or the elements 46 to 48 thereof, are produced from a material, for example steel, which has a considerably greater coefficient of thermal expansion than the material of the planet carrier 34 and than the material of the carrier element 29, which may both likewise be produced from steel. It is thus ensured that, during the assembly of the planetary gear box 30, smaller temperature differences and/or pressing-in forces are required than in the case of solutions known from the prior art in order to push the ring-shaped structural unit 45 between the components that are to be connected rotationally fixedly to one another, that is to say between the planet carrier 34 and the carrier element 29.

[0092] Since a not inconsiderable temperature increase in relation to the assembly situation of the planetary gear box 30 occurs during the operation of the gas turbine engine 10, the elements 46 to 48 of the structural unit 45 expand to a much greater extent than the planet carrier 34 and the carrier element 29. Owing to the wedge shape in the region of their circumferential end sides 46A to 48B, the elements 46 to 48 slide into one another in the circumferential direction and thus generate a joining pressure between the inner side 44 of the bore 42 and the outer side 49 of the structural unit 45 and between the inner side 50 of the structural unit 45 and the outer side 43 of the carrier element 29. The joining pressure that arises here effects the oversize that is required in each case for the rotationally fixed connection between the planet carrier 34 and the carrier element 29.

[0093] Here, the joining pressure is significantly influenced by the wedge angles to . Different wedge angles to of the elements 46 to 48 give rise, in the circumferential direction of the structural unit 45, to a non-uniform profile of the joining pressure between the planet carrier 34 and the structural unit 45 and between the structural unit 45 and the carrier element 29. For this reason, the configuration of the wedge angles to is dependent on the manner in which the joining pressure is to be distributed in the circumferential direction in a manner dependent on the respectively present usage situation. Here, it is possible for the joining pressure to be set so as to be constant, so as to increase or decrease, and/or so as to fluctuate, in the circumferential direction. Furthermore, the wedge angles to are also dependent on the number of elements 46 to 48, the length of the elements 46 to 48 in the radial direction, and the radial thickness of the elements 46 to 48.

[0094] Depending on the respectively present usage situation, the wedge angles , , and are predefinable in a range between 0 and 90, preferably 10 and 80, in order to be able to connect the carrier element 29 and the planet carrier 34 rotationally fixedly to one another to the desired degree.

[0095] Here, the stiffness of the elements 46 to 48 and thus of the structural unit 45 as a whole is greater the smaller the wedge angles , , and that are enclosed by the end sides 46A to 48B with the radial direction R. Furthermore, the stiffness of the elements 46 to 48 and thus of the structural unit 45 as a whole is greater the greater the wedge angles , , and that are enclosed by the end sides 46A to 48B with the tangents to the outer sides 49 or to the inner sides 50 respectively. By contrast to this, however, the temperature-induced clamping action of the structural unit 45 between the planet carrier 34 and the carrier element 29 decreases with increasing operating temperature of the planetary gear box 30 if the wedge angles to relative to the radial direction R are smaller or relative to the tangents are greater, because then, the sliding of the elements 46 to 48 into one another occurs to a lesser degree.

[0096] Most steels have a coefficient of expansion of between 1110.sup.6 K.sup.1 and 1310.sup.6 K.sup.1. If both the carrier element 29 or the planet bolt and the planet carrier 34 have a coefficient of thermal expansion of approximately 12.310.sup.6 K.sup.1, and if the structural unit 45, which constitutes a segmented ring, is formed from a material with a coefficient of thermal expansion of approximately 2010.sup.6 K.sup.1, then the ratio of the coefficients of thermal expansion is approximately 1 to 1.6, or has a value of approximately 0.6.

[0097] By contrast to this, metal alloys or steels also exist which have a considerably lower coefficient of thermal expansion, of approximately 3.810.sup.6 K.sup.1. The use of such materials in combination with conventionally used metal alloys results in a ratio of for example 0.2 between the coefficients of thermal expansion of the carrier element 29 and of the structural unit 45, and those of the planet carrier 34 and of the structural unit 45, respectively. For the present usage situation, a ratio between the coefficients of thermal expansion in a value range from 0.1 to 0.9 is preferred.

[0098] FIG. 5 shows a highly schematic stand-alone illustration of the element 46, wherein the solid outline shows the outer dimensions of the element 46 when the component temperature of the element 46 corresponds to the installation temperature. The dotted outline of the element 46 shows the component dimensions of the element 46 during the operation of the planetary gear box 30, when the component temperature is higher than the installation temperature. It is clear from the schematic illustration in FIG. 5 that, as a result of the increase in the operating temperature of the planetary gear box 30, the elements 46 to 48 of the structural unit 45 expand substantially in the circumferential direction, and together give rise to a higher joining pressure during the operation of the planetary gear box 30 than during and directly after the installation process.

[0099] FIG. 6 shows a partial longitudinal sectional view of a further embodiment of the planetary gear box 30 along a section line VI-VI denoted in more detail in FIG. 3. In the exemplary embodiment of the planetary gear box 30 shown in FIG. 6, the ring-shaped structural unit 45 again has multiple elements 55, 56 running in the circumferential direction, which elements have a wedge-shaped profile in the axial direction X. Here, the elements 55 bear with their substantially cylindrical radial end sides or inner sides 55A against the outer side 43 of the carrier element 29. By contrast to this, the elements 56 bear with their outer sides 56B or radial end sides against the inner side 44 of the bore 42 of the planet carrier 34. In addition, radial end sides or inner sides 56A of the elements 56 face toward radial end sides or outer sides 55B of the elements 55, and bear against these without a gap.

[0100] The coefficients of thermal expansion of the elements 55 and 56 are in turn greater than the coefficients of thermal expansion of the planet carrier 34 and of the carrier element 29, whereby the rotationally fixed connection between the planet carrier 34 and the carrier element 29 can be realized, by insertion of the structural unit 45, with relatively low joining forces and also small temperature differences between the planet carrier 34 and the structural unit 45, and between the structural unit 45 and the carrier elements 29, respectively.

[0101] In order to prevent the elements 55 and 56 from sliding axially out of the press fit during the operation of the planetary gear box 30, the elements 55 and 56 are secured by axial securing units 58 and 59. Here, the axial securing unit 58 constitutes a shaft collar of the carrier element 29. The axial securing unit 59 may be designed for example as a ring-shaped disk or else as a type of shaft nut, by means of which the elements 55 and 56 are prevented from sliding out of the press fit between the planet carrier 34 and the carrier element 29.

[0102] In the circumferential direction, the circumferential end sides of the elements 55 and 56 in the circumference illustrated in FIG. 7 each enclose an angle of 0 with the radial extent direction R of the structural unit 45, and are spaced apart from one another. An expansion of the elements 55 and 56 in the circumferential direction U is thus possible without thereby significantly influencing the press fit between the planet carrier 34 and the structural unit 45, and between the structural unit 45 and the carrier element 29, respectively.

[0103] Depending on the respectively present usage situation, it is also possible for the elements 55 or 56 to be formed integrally with the carrier element 29 or with the planet carrier 34, and for the structural unit 45 to comprise in each case only the elements 55 or 56.

[0104] FIG. 8 shows an illustration, substantially corresponding to FIG. 4, of a further exemplary embodiment of the planetary gear box 30, in the case of which the circumferential end sides 46A to 48B of the elements 46 to 48 do not enclose a constant angle with the radial extent direction R of the structural unit 45. This results from the fact that the circumferential end sides 46A to 48B of the elements 46 to 48 are of arcuate form. The arcuate design of the circumferential end sides 46A to 48B makes it possible for the joining pressure between the planet carrier 34 and the structural unit 45 and between the structural unit 45 and the carrier element 29 to be configured with a greater degree of freedom, and for any changes in stiffness of the elements in the circumferential direction to be compensated, and for a constant joining pressure in the circumferential direction to thus be generated.

LIST OF REFERENCE SIGNS

[0105] 9 Main axis of rotation [0106] 10 Gas turbine engine [0107] 11 Engine core [0108] 12 Air inlet [0109] 14 Low-pressure compressor [0110] 15 High-pressure compressor [0111] 16 Combustion device [0112] 17 High-pressure turbine [0113] 18 Bypass thrust nozzle [0114] 19 Low-pressure turbine [0115] 20 Core thrust nozzle [0116] 21 Engine nacelle [0117] 22 Bypass duct [0118] 23 Thrust fan [0119] 24 Support structure [0120] 26 Shaft, connecting shaft [0121] 27 Connecting shaft [0122] 28 Sun gear [0123] 29 Carrier element [0124] 30 Planetary gear box [0125] 32A to 32D Planet gear [0126] 34 Planet carrier [0127] 36 Linkage [0128] 38 Ring gear [0129] 40 Linkage [0130] 42 Bore of the planet carrier [0131] 43 Outer side of the carrier element [0132] 44 Inner side of the bore [0133] 45 Ring-shaped structural unit [0134] 46 Element [0135] 46A, 46B Circumferential end side [0136] 47 Element [0137] 47A, 47B Circumferential end side of the element [0138] 48 Element [0139] 48B Circumferential end side [0140] 49 Outer side of the structural unit [0141] 50 Inner side of the structural unit [0142] 55 Element [0143] 55A Inner side of the element, radial end side [0144] 55B Outer side of the element, radial end side [0145] 56 Element [0146] 56A Inner side of the element, radial end side [0147] 56B Outer side of the element, radial end side [0148] 58, 59 Axial securing unit [0149] 60 Device [0150] A Core airflow [0151] B Bypass airflow [0152] R Radial extent direction of the structural unit [0153] U Circumferential direction of the structural unit [0154] X Axial direction [0155] Angle [0156] Angle [0157] Angle [0158] Angle