MECHANICAL REDUCER FOR AN AIRCRAFT TURBOMACHINE

Abstract

Mechanical gearbox (110) for a turbomachine (1), particularly an aircraft turbomachine, the gearbox (110) comprising an oil distributor (116) which has a general star shape and comprises several interconnected arms (132), each of the arms (132) having at its radially external end (132a) a ring (134) which is axially clamped onto a satellite carrier (113) and / or a satellite support (120). Abbreviated figure: Figure 4

Description

Title of the invention: MECHANICAL REDUCER FOR AN AIRCRAFT TURBOMACHINE Technical field of the invention

[0001] The present invention relates to the field of mechanical reducers for turbomachinery, in particular aircraft, and in particular reducers equipped with lubricating oil distributors. Technical background

[0002] The state of the art includes in particular documents WO-A1-2010 / 092263, FR-A1-2 987 416, FR-A1-3 011 901, FR-A1-3 041 054 and FR-Al-3 058 493.

[0003] The role of a mechanical reducer is to modify the speed and torque ratio between the input shaft and the output shaft of a mechanical system.

[0004] New generations of turbofan engines, particularly those with a high bypass ratio, include a mechanical gearbox to drive the shaft of a fan. Typically, the purpose of the gearbox is to transform the high rotational speed of the power turbine shaft into a slower rotational speed for the fan-driving shaft.

[0005] Such a reduction gear comprises a central pinion, called the sun gear, a ring gear, and pinions called planet gears, which mesh between the sun gear and the ring gear. The planet gears are held by a frame called a planet carrier. The sun gear, ring gear, and planet carrier are planetary gears because their axes of revolution coincide with the longitudinal axis X of the turbomachine. The planet gears each have a different axis of revolution and are equally spaced on the same operating diameter around the axis of the planetary gears. These axes are parallel to the longitudinal axis X.

[0006] Several gearbox architectures exist. In the state of the art of turbofan engines, gearboxes are of the planetary or epicyclic type. In other similar applications, there are so-called differential or "compound" architectures.

[0007] - On a planetary gearbox, the planet carrier is fixed and the ring gear constitutes the output shaft of the device which rotates in the opposite direction to the solar.

[0008] - On an epicyclic reducer, the ring gear is fixed and the planet carrier constitutes the output shaft of the device which rotates in the same direction as the solar panel.

[0009] - On a differential reducer, no element is fixed for rotation. The ring rotates in the opposite direction to the solar panel and the satellite carrier.

[0010] Reducers can be composed of one or more meshing stages. This meshing is achieved in various ways such as by contact, by friction or by magnetic fields.

[0011] In this application, the term "stage" or "toothing" refers to a series of teeth interlocking with a series of complementary teeth. A toothing can be internal or external.

[0012] A satellite may comprise one or two gear stages. A single-stage satellite comprises teeth that may be straight, helical, or chevron-shaped, and whose teeth are located on the same diameter. These teeth cooperate with both the sun gear and the crown gear.

[0013] A two-stage satellite comprises two sets of teeth or two series of teeth which are located on different diameters. A first set of teeth cooperates with the sun gear and a second set of teeth cooperates with the crown gear.

[0014] One of the problems with a reducer concerns its lubrication.

[0015] Lubricating the various components of a gearbox is essential for the proper functioning of the system to prevent adverse events (gear seizure, pressure loss, bearing failure, etc.). A gearbox whose components are subjected to high mechanical stress, or which has a number of components requiring lubrication, has an inherently higher oil requirement. Distributing oil to all components presents a technical challenge in providing the flow rates necessary to ensure the proper functioning of each component at all operating points, while minimizing the number of parts and mechanical interfaces, and integrating easily within the gearbox to limit the overall size of the lubrication system.

[0016] Current lubrication solutions offer a single oil inlet for the gearbox housing. Distribution is carried out either from the front or upstream, or from the rear or downstream of the gearbox, by means of a distributor fixed to the planet carrier.

[0017] Current solutions for attaching a distributor to a planet carrier generally use a screw flange system. The flange is evenly spaced around the planet carrier, and each screw location adds extra bulk, complicating the design of the planet carrier in highly constrained areas.

[0018] The more the distributor fixing solutions allow drilling to be avoided in constrained areas of the planet carrier, the more the solution will be beneficial for the design of the planet carrier and therefore for the mass and reliability of the reducer.

[0019] The invention offers a solution to this problem, which is simple, effective and economical. Summary of the invention

[0020] The invention relates to a mechanical gearbox for a turbomachine (1), in particular for aircraft, the gearbox comprising:

[0021] - a solar array centered on a first axis,

[0022] - a crown centered on the first axis,

[0023] - satellites intercalated between the solar system and the corona and meshed with the solar system and the crown, the satellites being centered on second axes parallel to the first axis and distributed around the first axis, the satellites being traversed axially by supports,

[0024] - a satellite carrier centered on the first axis and comprising housings for mounting of the satellite supports, the satellite carrier comprising a first annular flange centered on the first axis and including first mounting holes for the satellite supports,

[0025] - an oil distributor which is fixed to the first flange,

[0026] characterized in that the distributor has a general star shape and comprises several branches connected together at the level of the first axis, each of the branches having at its radially external end a ring which is centered on one of the second axes and which is tightened axially on the first flange and / or one of said supports by an added nut.

[0027] The oil distributor is therefore no longer fixed to the planet carrier by clamping but by a system of rings tightened by added nuts. The distributor's attachment thus no longer uses screws, which is advantageous for several reasons. These include a reduction in the weight of the gearbox and an improvement in the design of the planet carrier, which does not require holes for or screws.

[0028] The reducer according to the invention may comprise one or more of the following features, taken individually or in combination with each other: - the ring is mounted around a cylindrical rim of the first flange, this cylindrical rim being centered on one of the second axes and defining one of the said first orifices; - the cylindrical rim includes a thread, in particular external, for screwing said nut; - the ring is mounted around a cylindrical rim at one end of the corresponding support, this cylindrical rim being centered on one of the second axes; - the number of branches and rings of the distributor is equal to the number of supports and satellites, the rings being respectively centered on all the second axes; - the branches are connected to each other by a core which includes an internal circuit for supplying oil to the branches; - each of the branches includes an internal pipe which is connected to said circuit; - the internal channel of each of the branches opens inside the ring, and is possibly in fluidic communication with an annular groove formed inside the ring around the second axis; - the internal channel of each of the branches is closed at its radially external end located on the side of the ring; - the internal channel of each of the branches is connected by a branch to an oil supply line of the corresponding support, this line having an end opposite the branch which is centered on the second corresponding axis; - the conduit is attached and fixed to the corresponding branch of the distributor; - the distributor further includes an oil supply port which is formed at a radially external end of an additional branch of the distributor;

[0029] — the oil supply port is oriented radially with respect to the first axis, or parallel to the first axis;

[0030] — the ring has an internal diameter greater than the internal diameter of the support corresponding;

[0031] — the ring is fretted onto the cylindrical rim;

[0032] — the cylindrical rim of the support is formed by an attached annular cover and fixed to the rest of the support;

[0033] — said at least one distributor is centered on said first flask;

[0034] - the distributor is made from a single piece, for example by machining;

[0035] - the distributor further includes or carries oil jets;

[0036] - the satellite carrier comprises two annular flanges centered on the first axis and connected together by bridges located at the periphery of the flanges, a second of the flanges including second mounting holes for the satellite supports.

[0037] The present invention also relates to a turbomachine, in particular for aircraft, comprising a reducer as described above. Brief description of the figures

[0038] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:

[0039] [Fig. 1] [Fig. 1] is a schematic axial cross-sectional view of an aircraft turbomachine,

[0040] [Fig.2] [Fig.2] is a partial and highly schematic axial section of a mechanical reducer,

[0041] [Fig.3] [Fig.3] is a schematic perspective view of a mechanical reducer,

[0042] [Fig.4] [Fig.4] is a schematic perspective view of an oil dispenser for a mechanical reducer according to a first embodiment of the invention,

[0043] [Fig.5] [Fig.5] is a very schematic front view of a variant embodiment of a reducer according to the invention,

[0044] [Fig.6] [Fig.6] is a schematic perspective view with a cross-section of the oil distributor of [Fig.4],

[0045] [Fig.7] [Fig.7] is a schematic perspective view with a larger-scale cross-section of an alternative embodiment of an oil dispenser according to the invention,

[0046] [Fig.8] [Fig.8] is a partial schematic cross-sectional view of another oil distributor according to the invention,

[0047] [Fig. 9] [Fig. 9] is a partial schematic axial cross-sectional view of a reducer according to the invention and shows a first example of mounting the oil distributor,

[0048] [Fig. 10] [Fig. 10] is a partial schematic axial cross-sectional view of another reducer according to the invention and shows a second example of mounting the oil distributor, and

[0049] [Fig. 11] [Fig. 11] is a partial schematic axial cross-sectional view of another reducer according to the invention and shows a third example of mounting the oil distributor. Detailed description of the invention

[0050] Figure 1 describes a turbomachine 1 which conventionally comprises a rotation shaft X, a fan S, a low-pressure compressor 1a, a high-pressure compressor 1b, an annular combustion chamber 1e, a high-pressure turbine Id, a low-pressure turbine 1e, and an exhaust nozzle Ih. The high-pressure compressor 1b and the high-pressure turbine Id are connected by a high-pressure shaft 2 and together form a high-pressure (HP) housing. The low-pressure compressor 1a and the low-pressure turbine 1e are connected by a low-pressure shaft 3 and together form a low-pressure (LP) housing.

[0051] The blower S is driven by a blower shaft 4 which is driven to the BP shaft 3 by means of a reducer 10. This reducer 10 is generally of the planetary or epicycloidal type.

[0052] The following description relates to a planetary type reducer in which the ring is mobile in rotation.

[0053] The reducer 10 is positioned in the upstream part of the turbomachine. A fixed structure schematically comprising, here, an upstream part 5a and a downstream part 5b which make up the motor or stator housing 5 is arranged to form an enclosure E surrounding the reducer 10. This enclosure E is here closed upstream by seals at the level of a bearing allowing the passage of the blower shaft 4, and downstream by seals at the level of the passage of the BP shaft 3.

[0054] Figure 2 shows a reducer 10 which can take the form of different architectures depending on whether certain parts are fixed or rotating. At the input, the reducer 10 is connected to the shaft BP 3, for example via internal splines 7a. Thus, the shaft BP 3 drives a planetary gear called the sun gear 11. Conventionally, the sun gear 11, whose axis of rotation coincides with that of the turbomachine X, drives a series of gears called planet gears 12, which are equally spaced on the same diameter around the axis of rotation X. This diameter is equal to twice the operating center distance between the sun gear 11 and the planet gears 12. The number of planet gears 12 is generally defined between three and seven for this type of application.

[0055] The set of satellites 12 is held by a frame called a satellite carrier 13. Each satellite 12 rotates around its own Y axis, and meshes with the ring 14. • In this planetary configuration, the set of satellites 12 is held by a satellite carrier 13 which is fixed to the motor or stator housing 5. Each satellite drives the ring which is brought to the blower shaft 4 via a ring carrier 15.

[0056] Each satellite 12 is mounted to rotate freely by means of a bearing 8, for example, a roller bearing or hydrodynamic bearing. Each bearing 8 is mounted on one of the axes 13a of the satellite carrier 13, and all the axes 13a are positioned relative to each other by means of a cage of the satellite carrier 13. There is a number of axes 13a and bearings 8 equal to the number of satellites 12. For reasons of operation, assembly, manufacturing, inspection, repair, or replacement, the axes 13a and cage may be separated into several parts.

[0057] For the same reasons mentioned above, the teeth of a reduction gear can be separated into several helices, each having a median plane. In the example shown, the ring gear 14 is separated into two half-ring gears: • An upstream half-crown 14a consisting of a rim 14aa and a mounting half-flange 14ab. The upstream helix of the reduction gear teeth is located on the rim 14aa. This upstream helix meshes with that of the satellite 12, which in turn meshes with that of the solar element 11. • A downstream half-crown 14b consisting of a rim 14ba and a mounting half-flange 14bb. The downstream helix of the reduction gear teeth is located on the rim 14ba. This downstream helix meshes with that of the satellite 12, which meshes with that of the solar 11.

[0058] The mounting half-flange 14ab of the upstream crown 14a and the mounting half-flange 14bb of the downstream crown 14b form the mounting flange 14c of the crown. The crown 14 is fixed to a crown carrier by assembling the mounting flange 14c of the crown and the mounting flange 15a of the crown carrier 15 using a bolted assembly, for example.

[0059] The arrows in [Fig. 2] describe the oil flow in the gearbox 10. The oil enters the gearbox 10 from the stator section 5 into a distributor 16 by various means, which will not be specified in this view because they are specific to one or more types of architecture. The distributor 16 is divided into two parts, generally each repeated with the same number of planetary gears 12. The injectors 17a lubricate the gear teeth, and the arms 17b lubricate the bearings. The oil is supplied to the injector 17a and exits through the end 17c to lubricate the gear teeth. The oil is also supplied to the arm 17b and flows through the feed port 17d of the bearing shaft 13a. The oil then circulates in an internal cavity 13b of the shaft 13a and then exits through orifices 13c in order to lubricate the bearings 8 of the satellites 12.

[0060] Figure 3 illustrates a reducer 110 according to the invention. In these figures, common elements are described by the same reference numerals. Where these elements have already been described in the preceding text in relation to Figures 1 and 2, these elements are designated by the same reference numeral plus one hundred.

[0061] The invention relates to a mechanical reducer 110 for a turbomachine, in particular for aircraft, such as that illustrated in [Fig.1].

[0062] The reducer 110 comprises:

[0063] - a solar 111 centered on a first axis X,

[0064] - a crown 114 centered on the first X axis, and

[0065] - satellites 112 intercalated between the solar 111 and the corona 114 and meshed with the solar 111 and the corona 114.

[0066] The satellites 112 are centered on second axes Y parallel to the first axis X and distributed around the first axis X.

[0067] The satellites 112 are axially traversed by supports 120 which allow the satellites 112 to be centered and guided in rotation around the second Y axes. As in the example shown, these supports 120 may be for rolling bearings 122. Alternatively, they could be supports 120 designed to form plain bearings. The satellites 112 are therefore mounted around these supports 120.

[0068] The reducer 110 further includes a satellite carrier 113 centered on the first X axis and having mounting housings for the supports 120 of the satellites 112.

[0069] The satellite carrier 113, which can be formed from a single piece, preferably comprises two annular flanges 128, 130 centered on the first axis X and connected together by bridges 131 located at the periphery of the flanges 128, 130. It could however comprise only one, as illustrated in [Fig.2].

[0070] A first of the flanges 128 includes first mounting holes 124 for the supports 120 of the satellites 112, and a second of the flanges 130 includes second mounting holes 126 for the supports 120 of the satellites 112.

[0071] In the example shown, each of the supports 120 has a tubular shape extending along a second axis Y and includes a first axial end mounted in the orifice 124 and a second axial end, opposite to the first end, which is mounted in the orifice 126.

[0072] The reducer 110 further includes an oil distributor 116 which is preferably centered on the first axis X and fixed on the first flange 128.

[0073] One of the particularities of the invention is related to the configuration of the oil distributor 116, a first embodiment of which is illustrated in [Fig.4].

[0074] The distributor 116 has a general star shape and comprises several branches 132 connected together at the level of the first axis X.

[0075] Each of the branches 132 has at its radially external end 132a a ring 134 which is centered on one of the second axes Y and which is tightened axially on the first flange 128 and / or one of the aforementioned supports 120 by an added nut 136.

[0076] The number of branches 132 and rings 134 of the distributor can be equal to the number of supports 120 and satellites 112, the rings 134 being respectively centered on all the second axes Y. In the case where the reducer includes for example three satellites 112, it is therefore understood that the distributor 116 will include three rings 134.

[0077] In the variant illustrated in [Fig.5], the number of branches 132 and rings 134 of the distributor is less than the number of supports 120 and satellites 112. In this example, the number of rings 134 is three while the number of satellites 112 is six.

[0078] Fig. 5 also shows that the distributor 116 can include several oil jets 135 and / or several oil supply lines 148 for the supports 120.

[0079] The rings 134 can be regularly distributed around the axis A as illustrated in [Fig.4], or on the contrary distributed in a non-regular way around this axis A as is the case in [Fig.5].

[0080] The branches 132 can be connected to each other by a core 138 which is located at the level of the X axis and which includes an internal circuit 140 for supplying oil to the branches 132. The core is not limited to the round shape shown in [Fig.4].

[0081] Each of the branches 132 preferably includes an internal conduit 142 which is connected to this circuit 140. Figures 6 to 9 illustrate conduits 142 of this type.

[0082] The internal channel 142 of each of the branches 132 can open into the corresponding ring 134, as illustrated in [Fig. 8]. This channel 142 can also be in fluidic communication with an annular groove 144 formed inside the ring 134 around the second axis Y, as illustrated in [Fig. 9].

[0083] Alternatively, the internal channel 142 of each of the branches 132 can be closed at its radially external end located on the side of the ring 134, as can be seen in [Fig.6]. It is closed either by as-casting or by a plug, for example.

[0084] Furthermore, the internal channel 142 of each of the branches 132 can be connected by a branch 146 to an oil supply conduit 148 of the corresponding support 120, as illustrated in [Fig.6].

[0085] The conduit 148 has an end 148a opposite the branch 146 which is centered on the corresponding second axis Y ([Fig.6]).

[0086] The conduit 148 can be attached and fixed to the corresponding branch 132 of the distributor 116. For this purpose, the conduit 148 can include one or more tabs 150 applied to the branch 132 and screwed into this branch by means of screws (not shown - figures 4 and 6).

[0087] The distributor 116 may further include an oil supply port 152 formed at a radially external end 154a of an additional branch 154 of the distributor 116 (Figures 4, 6, and 7). Figure 4 shows that this additional branch 154 may be located between two of the aforementioned branches 132. This figure also shows that all branches 132, 154 of the distributor 116 preferably extend in the same plane perpendicular to the X-axis.

[0088] The oil supply port 152 can be oriented radially with respect to the first X-axis ([Fig. 7]) or parallel to the first X-axis ([Fig. 6]). These figures show that the port 152 receives, by male-female engagement, an end 156 of an oil supply element 158 ​​of the distributor 116.

[0089] With regard to the mounting of the distributor 116, several possibilities are conceivable.

[0090] In the embodiment of [Fig.9] for example, each ring 134 is mounted around a cylindrical rim 160 of one end of the corresponding support 120. This cylindrical rim 160 is centered on the second Y axis of this support 120.

[0091] The cylindrical rim 160 includes a thread 162, in particular external, for screwing the nut 136.

[0092] In the example shown, each ring 134 is axially clamped between the nut 136 on one side, and the support 120 on the other, the support 120 having for example an annular rib 164 on which the ring 120 axially rests.

[0093] In this embodiment, it can be seen that the cylindrical rim 160 further includes at least one orifice 166 for fluidic communication of the groove 144 of the ring 134 with the interior of the support 120.

[0094] In the embodiment of [Fig. 10], each ring 134 is also mounted around a cylindrical rim 160 of one end of the corresponding support 120. This rim 160 can be formed in one piece with the corresponding support 120 or be formed by an annular cover attached to the support 120 and centered on the Y-axis.

[0095] In the example shown, each ring 134 is axially clamped against the annular rib 164 as well as on the first flange 128.

[0096] In the embodiment of [Fig. 11], each ring 134 is mounted around a cylindrical rim 170 of the first flange 128. The cylindrical rim 170 is centered on the second axis Y of this support 120.

[0097] The cylindrical rim 170 includes a thread 172, in particular external, for screwing the nut 136.

[0098] In the example shown, each ring 134 is axially clamped between the nut 136 on one side, and the first flange 128 on the other.

[0099] Figures 9 to 11 show that each ring 134 preferably has an internal diameter Dintl greater than the internal diameter Dint2 of the corresponding support 120. Tightening each nut 136 may be sufficient to hold the rings, and therefore the distributor 116, onto the planet carrier. However, it is also possible to shrink-fit the rings 134 onto the aforementioned flanges 170 to reinforce the hold of the distributor 112 on the planet carrier 113.

[0100] The invention offers several advantages such as, for example:

[0101] - a simplification of the distributor assembly,

[0102] - a design ease for the satellite carrier,

[0103] - etc.

Claims

Demands

1. A mechanical reducer (110) for a turbomachine (1), in particular for aircraft, the reducer (110) comprising: - a sun gear (111) centered on a first axis (X), - a ring gear (114) centered on the first axis (X), - planet gears (112) interposed between the sun gear (111) and the ring gear (114) and meshed with the sun gear (111) and the ring gear (114), the planet gears (112) being centered on second axes (Y) parallel to the first axis (X) and distributed around the first axis (X), the planet gears (112) being axially traversed by supports (120), - a planet carrier (113) centered on the first axis (X) and having mounting housings for the supports (120) of the planet gears (112), the planet carrier (113) having a first annular flange (128) centered on the first axis (X) and including first mounting holes (124) for the supports (120) of the satellites (112), - at least one oil distributor (116) which is fixed on the first flange (128),characterized in that the distributor (116) has a general star shape and comprises several arms (132) connected together at the first axis (X), each of the arms (132) having at its radially external end (132a) a ring (134) which is centered on one of the second axes (Y) and which is axially clamped onto the first flange (128) and / or one of said supports (120) by an attached nut (136).

2. Reducer (110) according to claim 1, in which the ring (134) is mounted around a cylindrical rim (170) of the first flange (128), this cylindrical rim (170) being centered on one of the second axes (Y) and defining one of said first orifices (124).

3. Reducer (110) according to claim 2, in which the cylindrical rim (170) includes a thread (172), in particular external, for screwing said nut (136).

4. Reducer (110) according to claim 1, in which the ring (134) is mounted around a cylindrical rim (160) of one end of the corresponding support (120), this cylindrical rim (160) being centered on one of the second axes (Y).

5. Reducer (110) according to claim 4, wherein the cylindrical rim (160) includes a thread (162), in particular external, for screwing said nut (136).

6. Reducer (110) according to any one of the preceding claims, wherein the number of arms (132) and rings (134) of the distributor (116) is equal to the number of supports (120) and satellites (112), the rings (134) being respectively centered on all second axes (Y).

7. Reducer (110) according to any one of the preceding claims, in which the branches (132) are connected to each other by a core (138) which includes an internal circuit (140) for supplying oil to the branches (132).

8. Reducer (110) according to claim 7, wherein each of the branches (132) comprises an internal conduit (142) which is connected to said circuit (140).

9. Reducer (110) according to claim 8, wherein the internal channel (142) of each of the branches (132) opens into the inside of the ring (134), and is optionally in fluidic communication with an annular groove (144) formed inside the ring (134) around the second axis (Y).

10. Reducer (110) according to claim 8, wherein the internal channel (142) of each of the branches (132) is closed at its radially external end located on the side of the ring (134).

11. Reducer (110) according to any one of claims 8 to 10, wherein the internal channel (142) of each of the branches (132) is connected by a branch (146) to an oil supply conduit (148) of the corresponding support, this conduit (148) having an end (148a) opposite the branch (146) which is centered on the corresponding second axis (Y).

12. Reducer (110) according to claim 11, wherein the conduit (148) is brought and fixed on the corresponding branch (132) of the distributor (116).

13. Reducer (110) according to any one of the preceding claims, wherein the distributor (116) further comprises an oil supply port (152) which is formed at a radially external end of an additional branch (154) of the distributor (116).

14. Reducer (110) according to any one of the preceding claims, wherein the distributor (116) further comprises or carries oil jets (135).

15. Reducer (110) according to any one of the preceding claims, wherein the distributor (116) is made in one piece, for example by machining.

16. Turbomachine (1), in particular aircraft turbomachine, comprising a reducer (110) according to any one of the preceding claims.

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