Improved reduction gear for fixing a ring gear

Abstract

A reduction gear for a turbomachine (6) extending around an axis of rotation (X-X) comprising a ring gear (9) connected to a ring gear carrier (12), wherein according to a sectional view along a plane comprising the axis (X-X), the ring gear carrier (12) has an inner section (124) extending continuously from an inner shaft (122) up to a ring gear support (128), an outer section (126) and the ring gear support (128), the inner section (124) extending up to a radius R1 with respect to the axis (X-X), the outer section (126) forming an angle β with the inner section (124), the ring gear support (128) forming an angle α with the outer section (126) and being fixed to the ring gear (9) via a bolt connection realized at a nominal radius R2 with respect to the axis (X-X), wherein the ratio R1 / R2 is between 0.3 and 0.7.

Description

Technical Field

[0001] This invention relates to a reduction gear, particularly a reduction gear for a dual-flow turbine. Background Technology

[0002] New-generation dual-flow turbines, particularly those with high bypass ratios, include mechanical reduction gears for driving the turbine shaft. Typically, the function of the reduction gear is to convert the rotational speed of the power turbine shaft (called the rapid flow) into a slower speed for driving the turbine shaft. Document FR3092889 thus illustrates an example of a known structure for a turbine reduction gear.

[0003] This type of reduction gear comprises a center gear, called the central gear, a ring gear, and numerous gears called planetary gears, which engage between the center gear and the ring gear. These planetary gears are held in place by a frame called a satellite carrier. The center gear, ring gear, and planetary gear carrier are planetary gears because their axes of rotation coincide with the longitudinal axis X of the turbine. Each planetary gear has a different axis of rotation, which is evenly distributed around the axis of the planetary gear on the same working diameter. These axes are parallel to the longitudinal axis X.

[0004] Several reduction gear architectures exist. In the prior art of dual-flow turbines, the reduction gears are planetary or epicycloidal. In other similar applications, architectures known as differential or compound reduction gears exist.

[0005] In a planetary reduction gear, the planetary gear carrier is fixed, and the gear ring forms the output shaft of the device, which rotates in the opposite direction to the central gear.

[0006] In an epicycloid reduction gear, the gear ring is fixed, and the planetary gear set up the output shaft of the device, which rotates in the same direction as the central gear.

[0007] In differential reduction gears, there are no stationary components during rotation. The gear ring rotates in the opposite direction to the central gear and the planetary gear carrier.

[0008] A reduction gear can consist of one or more meshing stages. This meshing can be provided in different ways, such as through contact, friction, or even a magnetic field.

[0009] There are several types of contact engagement, such as contact engagement with straight teeth or herringbone teeth.

[0010] A recurring problem is related to the axial movement of the gear ring, especially when affected by the centrifugal deformation of the gear ring bracket during operation.

[0011] Therefore, the present invention aims to respond to this problem at least partially. Summary of the Invention

[0012] Therefore, the present invention relates to a reduction gear for a turbine extending around a rotating shaft, comprising a gear ring connected to a gear ring carrier extending between an inner shaft extending around the shaft and the gear ring, wherein...

[0013] –According to a sectional view along a plane including the axis, the gear ring bracket extends continuously from the inner axis to the inner section, outer section, and gear ring support of the gear ring support.

[0014] – The inner section extends relative to the axis up to radius R1.

[0015] – The outer segment and the inner segment form an angle β.

[0016] – The gear ring support forms an angle α with the outer section and is fixed to the gear ring relative to the shaft via a bolt connection with a nominal radius R2.

[0017] The feature is that the ratio R1 / R2 is between 0.3 and 0.7, the angle α is between 60° and 85°, and the angle β is between 150° and 175°.

[0018] According to one example, the gear ring bracket forms a curved or circular section connecting the gear ring support frame and the outer section.

[0019] According to one example, the inner segment is a straight line.

[0020] According to one example, the outer segment is a straight line.

[0021] According to one example, the ratio R1 / R2 is between 0.4 and 0.6.

[0022] According to one example, the angle α is between 65° and 80°.

[0023] According to one example, the angle β is between 155° and 170°.

[0024] The present invention also relates to a turbine comprising the previously proposed reduction gear.

[0025] The present invention also relates to an aircraft that includes a turbine of this type. Attached Figure Description

[0026] The invention and its advantages will be better understood after reading the detailed description given below of various embodiments of the invention by way of non-limiting examples.

[0027] Figure 1 A general turbine structure is shown.

[0028] Figure 2 This is a view of the turbine reduction gear.

[0029] Figure 3 This is a cross-sectional view of a reduction gear according to one aspect of the present invention.

[0030] Figure 4 This is a schematic diagram of the gear ring bracket of the reducer.

[0031] In all the accompanying drawings, common elements are labeled with the same reference numerals. Detailed Implementation

[0032] Figure 1 A turbine 1 is described, which conventionally includes a fan S, a low-pressure compressor 1a, a high-pressure compressor 1b, an annular combustion chamber 1c, a high-pressure turbine 1d, a low-pressure turbine 1e, and an exhaust nozzle 1h. The high-pressure compressor 1b and the high-pressure turbine 1d are connected via a high-pressure shaft 2 and form a high-pressure rotor (HP) with the high-pressure shaft 2. The low-pressure compressor 1a and the low-pressure turbine 1e are connected via a low-pressure shaft 3 and form a low-pressure rotor (BP) with the low-pressure shaft 3.

[0033] The fan S is driven by the fan shaft 4, which is driven by the low-pressure shaft 3 through the reduction gear 6. This reduction gear is typically a planetary or rotary type.

[0034] Although the following description refers to planetary or rotary reduction gears, it also applies to mechanical differential gears in which three components (planetary gear carrier 10, ring gear 9, and center gear 7) are rotatable, and the rotational speed of one of these components depends specifically on the speed difference between the other two components.

[0035] The reduction gear 6 is positioned in the upstream portion of the turbine. This schematically includes a fixed structure comprising the upstream portion 5a and the downstream portion 5b of the engine housing or stator 5, configured to form a casing E surrounding the reduction gear 6. Here, the casing E is formed upstream by sealing elements (e.g., washers at the bearings allowing the fan shaft 4 to pass through), and downstream by sealing elements (e.g., washers at the intersection of the low-pressure shaft 3).

[0036] Figure 2 A reduction gear 6, also known as a mechanical reducer, is described. Depending on whether certain components are fixed or rotatable, the reduction gear can have different structures. On the input side, the reduction gear 6 is connected to the low-pressure shaft 3, for example, via spline 7a. Therefore, the low-pressure shaft 3 drives a planetary gear, referred to as the center gear 7. Typically, the center gear 7, whose axis of rotation coincides with the axis of rotation of the turbine X, drives a series of gears called planetary gears 8, which are evenly distributed around the axis of rotation X on the same diameter. This diameter is equal to twice the working space between the axes of rotation of the center gear 7 and the planetary gears 8. For this type of application, the number of planetary gears 8 is typically limited to between 3 and 7.

[0037] The planetary gears 8 are held in place by a frame called the planetary gear carrier 10. Each planetary gear 8 rotates about its own axis Y and meshes with a ring gear 9.

[0038] Two structures are distinguished here.

[0039] In the rotating structure, all planetary gears 8 drive the planetary gear carrier 10 to rotate about the turbine axis X. The ring gear is fixed to the engine housing or stator 5 via the ring gear bracket 12, and the planetary gear carrier 10 is attached to the wind turbine shaft 4.

[0040] In the planetary configuration, all planetary gears 8 are secured by a satellite bracket 10, which is fixed to the engine housing or stator 5. Each planetary gear also secures a ring gear, which is attached to the fan shaft 4 via a ring gear bracket 12.

[0041] Each planetary gear 8 is rotatably mounted via a bearing 11, for example, a rolling element or a hydrodynamic bearing. Each bearing 11 is mounted on a shaft 10b of the planetary gear carrier 10, and all shafts are positioned relative to each other via one or more structural frames 10a of the planetary gear carrier 10. The number of shafts and bearings is equal to the number of satellites. These shafts and frames may be divided into several parts for operation, assembly, monitoring, maintenance, or replacement.

[0042] For the same reason mentioned earlier, the teeth of a reduction gear can be divided into several helices. In the example shown, we detail the operation of a reduction gear with several helices, where the gear ring is divided into two half-gear rings:

[0043] A front half-gear ring 9a is formed by a rim 9aa and a semi-fastening flange 9ab. The front helix of the reduction gear teeth is found on the rim 9aa. This helix meshes with the helix of the planetary gear 8, which meshes with the helix of the central gear 7.

[0044] A rear half-gear ring 9b is formed by a rim 9ba and a semi-fastening flange 9bb. The rear helix of the reduction gear teeth is found on the rim 9ba. This helix meshes with the helix of the planetary gear 8, which meshes with the helix of the central gear 7.

[0045] The semi-fastening flange 9ab of the front gear ring 9a and the semi-fastening flange 9bb of the rear gear ring 9b form the fastening flange 9c of the gear ring. For example, the gear ring 9 is fastened to the gear ring bracket 12 by assembling the fastening flange 9c of the gear ring and the fastening flange 12a of the gear ring bracket 12 by means of a bolt assembly.

[0046] Figure 2The arrows depict the path of the oil in the reduction gear 6. Oil reaches the reduction gear 6 from the stator portion 5 in the distributor 13 via different pathways not specifically shown in this view, as they are tailored to one or more types of structures. The distributor is typically divided into two sections, each consisting of the same number of planetary gears. Injector 13a functions to lubricate the gear teeth, and arm 13b functions to lubricate the bearings. Oil is supplied to injector 13a to exit near end 13c, thus lubricating the gear teeth. Oil is also supplied to arm 13b and circulates via the oil supply opening 13d of the bearing. The oil then circulates through the shaft into one or more buffers 10c and exits through opening 10d, thus lubricating the bearings of the planetary gears.

[0047] refer to Figure 3 and 4 Now, an example of the structure of a reduction gear according to one aspect of the present invention is described. Figure 3 This is a cross-sectional view of an example of a reduction gear according to one aspect of the present invention. Figure 4 These are schematic diagrams of the gear ring bracket for a reduction gear, highlighting its geometry. Only the gear ring bracket and the gear ring are shown in these figures.

[0048] These figures show the reduction gear 6, including the gear ring bracket 12 that holds the gear ring 9 in place. Both the gear ring bracket 12 and the gear ring 9 can rotate about the axis of rotation X–X.

[0049] The gear ring bracket 12 forms an arm from the inner shaft of the reduction gear 1 to an outer section that forms a support for the gear ring 9.

[0050] When considered in a sectional view based on a plane including the rotation axis X–X, the gear ring bracket 12 includes an inner section 124, an outer section 126, and a gear ring support 128, which extend continuously from the rotation axis X–X to the gear ring support.

[0051] Typically, from the hub 122 of the gear carrier 12, the inner section 124 extends radially or at an angle relative to the axis of rotation X–X, the hub 122 typically arranged around a fixed or movable shaft defining the axis of rotation X–X. The inner section 124 extends relative to the axis of rotation X–X to a first radius R1. The inner section 124 is typically linear.

[0052] The outer segment 126 follows the inner segment 124, extending from the first radius R1. The outer segment 126 is not aligned with the inner segment 124. The inclination of the outer segment 126 relative to the inner segment 124 forms an angle β, which is between 150° and 175°, or for example between 155° and 170°, or even between 160° and 170°, or even between 160° and 165°.

[0053] The outer segment 126 is usually linear.

[0054] The gear ring support 128 extends following the outer section 126 and includes an end to which the gear ring 9 is typically bolted. Therefore, 129 denotes the through groove formed in the gear ring support 128 and in the gear ring 9 for achieving the bolted connection between these two elements.

[0055] The gear ring support 128 forms an angle α with the outer section 126. Angle α is between 60° and 85°, or between 65° and 80°, or between 70° and 75°. The gear ring support 128 may be parallel to or not relative to the axis of rotation X–X. For example, the gear ring support 128 may be a straight line.

[0056] The gear ring support 128 defines a support region in which the gear ring 9 is positioned. This support region is located at a second radius R2 relative to the rotation axis X–X. Therefore, radius R2 is the implantation radius of the bolted connection between the gear ring support 128 and the gear ring 9, i.e., in… Figure 4 The nominal radius of hole 129 in the example shown.

[0057] The gear ring bracket 12 makes the ratio between radii R1 and R2 between 0.3 and 0.7, or for example between 0.35 and 0.65, or even between 0.4 and 0.6, or between 0.45 and 0.55.

[0058] The intersection between the outer section 126 and the gear ring support 128 is typically formed by a curved or rounded section 127, which specifically avoids the formation of sharp edges, thus improving the mechanical strength of the assembly.

[0059] The proposed geometry, combined with parameters R1, R2, α, and β, improves the mechanical strength of the gear ring support 12, particularly limiting or even eliminating axial movement of the gear ring caused by centrifugal force during operation. In fact, conventional reduction gears suffer from problems related to gear ring support deformation, and therefore from axial movement of the gear ring due to centrifugal effects, which generate significant stress on the gear teeth. The reduction gear 6 proposed above allows for a response to faults.

[0060] For example, reduction gear 6 is a planetary reduction gear with a single or two-stage rotating gear ring and rolling bearings or hydrodynamic bearings.

[0061] The reduction gear 6 mentioned above can be specifically used in turbine engines, such as turbojet engines, for example, see reference. Figure 1 The turbine engine shown is specifically designed for use in aircraft.

[0062] Although the invention has been described with reference to specific embodiments, it will be apparent that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. Specifically, individual features of the different embodiments shown / mentioned may be combined to form additional embodiments. Therefore, the specification and drawings should be considered illustratively and not restrictively.

[0063] It is equally evident that all features described in the reference method can be transposed individually or in combination to the apparatus, and conversely, all features described in the reference apparatus can be transposed individually or in combination to the method.

Claims

1. A reduction gear (6) for a turbine, the reduction gear extending about a rotational axis (X–X) and including a gear ring (9) connected to a gear ring carrier (12) extending between an inner shaft (122) extending about the axis (X–X) of the gear ring (9), in – The gear ring bracket (12) has an inner section (124), an outer section (126) and a gear ring support (128), wherein the inner section (124) and the outer section (126) extend continuously from the inner shaft (122) to the gear ring support (128). –The inner segment (124) extends relative to the axis (X–X) up to radius R1, –The outer segment (126) and the inner segment (124) form an angle β, – The gear ring support frame (128) forms an angle α with the outer section (126) and is fixed to the gear ring (9) relative to the axis (X–X) via a bolt connection achieved at a nominal radius R2. characterized in that The ratio R1 / R2 is between 0.3 and 0.7, the angle α is between 60° and 85°, and the angle β is between 150° and 175°.

2. The reduction gear (6) according to claim 1, wherein The gear ring bracket (12) includes a circular section (127) that forms a connection between the gear ring support frame (128) and the outer section (126).

3. The reduction gear (6) according to claim 1, wherein, The inner section (124) is a straight line.

4. The reduction gear (6) according to claim 1, wherein, The outer segment (126) is a straight line.

5. The reduction gear (6) according to claim 1, wherein, The ratio R1 / R2 is between 0.4 and 0.

6.

6. The reduction gear (6) according to claim 1, wherein, Angle α is between 65° and 80°.

7. The reduction gear (6) according to claim 1, wherein, Angle β is between 155° and 170°.

8. A turbine comprising a reduction gear (6) according to claim 1.

9. An aircraft comprising the turbine according to claim 8.

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