Planetary gear reducers for aircraft turbine engines

Abstract

A planetary gear reducer (10) for an aircraft turbine engine, the gear reducer comprising a rotatable sun gear, a rotatable ring gear (9) and planetary gears, the planetary gears meshing with the sun gear and the ring gear and carried by a planet carrier intended to be fixed to a stator, the gear reducer further comprising an annular groove for recovering and guiding lubricating oil, the annular groove being installed around the ring gear, characterized in that the gear reducer further comprises an annular guide portion (22), the annular guide portion being fixed to the ring gear and being configured to guide radially outflowing oil toward the outside of the ring gear to the groove by means of centrifugal force, the groove comprising an annular chamber (18) and an annular duct (20), the annular chamber being axially away from a central plane (P) substantially passing through the center of the ring gear, the annular duct being located on one side of the chamber and entering the chamber.

Description

Technical Field

[0001] The present invention relates to the field of aircraft turbine engines, in particular twin-flow turbojets comprising a planetary gear reducer. The invention is more particularly directed to a device for recovering and directing the oil required for lubricating the gear reducer. Background Art

[0002] The prior art includes in particular documents WO-A1-2010 / 092263, FR-A1-2 987 416 and FR-A1-3 041054.

[0003] The function of a mechanical gear reducer is to change the speed ratio and torque ratio between the input shaft and the output shaft of a mechanism.

[0004] New generation twin-flow turbojets, especially those with high bypass ratios, include a mechanical gear reducer to drive the shaft of the blower (also called a "fan"). Typically, the purpose of the gear reducer is to convert the so-called rapid rotational speed of the shaft of the power turbine to a slower rotational speed of the shaft driving the fan.

[0005] The gear reducer comprises a central pinion gear (called a sun gear), a ring gear and pinions (called planet gears), the planet gears meshing between the sun gear and the ring gear. The planet gears are held by a frame called a planet carrier. The sun gear, the ring gear and the planet carrier are planetary gear arrangements, because the axes of rotation of the sun gear, the ring gear and the planet carrier coincide with the longitudinal axis X of the turbine engine. The planet gears each have a different axis of rotation Y, and the planet gears are equidistantly distributed on the same running diameter around the axis of the planetary gear arrangement. These axes Y are parallel to the longitudinal axis X.

[0006] There are various gear reducer designs. In the prior art of twin-flow turbojets, the gear reducers are of the planetary or planetary type. In other similar applications, there are so-called differential or "compound" architectures.

[0007] -In a planetary gear reducer, the planet carrier is fixed and the ring gear is the output shaft of the device, which rotates in the opposite direction of the sun gear.

[0008] -On a planetary gear reducer, the ring gear is fixed and the planet carrier is the output shaft of the device, which rotates in the same direction as the sun gear.

[0009] -On a compound gear reducer, there is no fixed element when rotating. The ring gear rotates in the opposite direction of the sun gear and the planet carrier.

[0010] Gear reducers can have one or more meshing stages. The meshing is achieved in different ways, such as contact, friction or magnetic field. There are various types of contact meshing, such as spur gear meshing and herringbone gear meshing.

[0011] Gear reducers must be lubricated, and supplying lubricating oil to the rotating parts of a gear reducer can be problematic. Oil is usually supplied to the gear reducer by a lubricating oil distributor.

[0012] In the case of a planetary gear reducer, the oil that circulates in the gear reducer to lubricate the rolling elements and the teeth is discharged peripherally by centrifugal action through the ring gear, which can rotate at speeds of up to approximately 3000 revolutions per minute.

[0013] It has been proposed to place grooves around the gear ring of the gear reducer for recovering and directing the oil, the grooves being aligned with the oil outlet of the gear ring. However, the oil ejected into the grooves tends to rebound and return to the gear reducer. In addition, aeration and foaming of the oil may occur due to the high-speed projection of the oil on the walls of the grooves.

[0014] Therefore, the oil must be recovered as efficiently as possible and directed to the outside of the ring gear in order to:

[0015] -After being cooled, it is injected into the lubrication circuit of the gear reducer;

[0016] - Minimize hot oil splashing out of the gear reducer, thereby limiting:

[0017] ○ Heat exchange between the oil and the housing that carries the gear reducer,

[0018] ○The oil storage capacity in the gear reducer housing and the size of the oil tank;

[0019] -Limiting oil consumption through the exhaust circuit of the housing containing the gear reducer.

[0020] The present invention aims to meet these objectives in a simple and inexpensive manner. Summary of the invention

[0021] The present invention relates to an epicyclic gear reducer for an aircraft turbine engine, the gear reducer comprising a rotatable sun gear, a rotatable ring gear and planetary gears, the planetary gears meshing with the sun gear and the ring gear and carried by a planet carrier intended to be fixed to a stator, the gear reducer further comprising an annular groove for recovering and guiding lubricating oil, the annular groove being installed around the ring gear, characterized in that the gear reducer further comprises an annular guide portion, the annular guide portion being fixed to the ring gear and being configured to guide radially outflowing oil to the groove toward the outside of the ring gear by means of centrifugal force, the groove comprising:

[0022] - an annular chamber which is axially remote relative to a central plane passing substantially through the center of the ring gear, and

[0023] An annular duct located at one side of the chamber and entering the chamber, the annular duct being configured to receive the oil guided via the guide portion and ensure that the oil flows to the chamber.

[0024] In a planetary gear reducer, the lubricating oil passes radially through the ring gear and is ejected radially outwards by centrifugal action. The present invention proposes to recover and guide this oil through a groove, which is not intended to directly recover the ejected oil. In fact, the groove is axially offset relative to the oil outlet of the ring gear and receives the ejected oil through an annular guide. The guide captures the oil and redirects it to the chamber in the groove.

[0025] The invention thus makes it possible to increase the volume capacity of the groove without being limited by the radial space available at the oil outlet of the ring gear. Furthermore, the risk of oil splashing is limited, since the guides direct the oil to the chamber of the groove.

[0026] The use of a guide has several advantages. The shape of the guide can limit the splashing of oil onto the walls of the guide. Taking into account the radial position and the circumferential speed that are slightly higher than those of the oil outlet of the ring gear, the impact area of ​​the oil on the guide is advantageously located at a predetermined distance from the gear reducer, thereby enabling the oil film to be provided with additional energy. The combination of the guide and the oil outlet of the ring gear perpendicular thereto replaces the groove of the prior art and therefore has no impact on the space requirements in the housing for mounting and lubricating the gear reducer. The guide then helps to guide the oil into the chamber of the groove, which can be located upstream or downstream. To this end, it is conceivable to have different shapes and geometric configurations (for example, a truncated cone) at the outlet of the guide to promote the flow of oil to the chamber.

[0027] The gear reducer according to the present invention may include one or more of the following features, which may be used alone or in combination with each other:

[0028] - the annular chamber defines a first upper semicircular groove having a U-shaped axial cross section and a second lower semicircular groove having a U-shaped axial cross section, the first upper semicircular groove generally extending from 9 o'clock to 12 o'clock and from 12 o'clock to 3 o'clock by analogy with the dial of a clock, the second lower semicircular groove generally extending from 9 o'clock to 6 o'clock and from 6 o'clock to 3 o'clock by analogy with the dial of a clock,

[0029] - said first groove comprises a bottom defined by an inner cylindrical wall of the chamber, and said second groove comprises a bottom defined by an outer cylindrical wall of the chamber,

[0030] - the outer cylindrical wall comprises radial openings for draining the oil,

[0031] - the inner cylindrical wall and the outer cylindrical wall have axes which are not aligned with each other and / or with the longitudinal axis of the gear reducer,

[0032] - a first groove connected to a radially inner annular wall forming part of the duct, and a second groove connected to a radially outer annular wall forming part of the duct,

[0033] - a perforated annular baffle is housed in the chamber and is configured to degas the oil,

[0034] The partition comprises a first section extending into the first groove substantially at the radially inner annular wall and a second section extending into the second groove substantially at the radially outer annular wall.

[0035] The invention also relates to an aircraft turbine engine comprising a planetary gear reducer comprising a rotatable outer cover for recovering oil and surrounded by at least one groove as described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The invention will be better understood, and further details, features and advantages of the invention will become apparent, from the following description made with reference to the accompanying drawings, in which:

[0037] [ Figure 1 ] Figure 1 A schematic axial cross-section diagram of a planetary gear reducer of a turbine engine is shown,

[0038] [ Figure 2 ] Figure 2 It is a partial schematic diagram of an axial section and a partial schematic diagram of a groove of a gear reducer according to the prior art,

[0039] [ Figure 3 ] Figure 3 The axial cross-sectional partial schematic diagram and the perspective partial schematic diagram of the gear reducer according to the present invention are shown. By analogy with the dial of a clock, the cross-sectional plane is located at 12 o'clock.

[0040] [ Figure 4 ] Figure 4 Shows Figure 3 The axial cross-sectional partial schematic diagram and the perspective partial schematic diagram of another part of the gear reducer are shown. By analogy with the dial of a clock, the section plane is located at 6 o'clock.

[0041] [ Figure 5 ] Figure 5 yes Figure 3 and Figure 4 A schematic perspective view of the groove of a gear reducer,

[0042] [ Figure 6 ] Figure 6 yes Figure 3 and Figure 4 Another schematic perspective view of the groove of the gear reducer,

[0043] [ Figure 7 ] Figure 7 yes Figure 3 and Figure 4 Another partial schematic perspective view of a groove of a gear reducer. DETAILED DESCRIPTION

[0044] Figure 1 Very schematically shown is a planetary gear reducer for a turbine engine having a planetary gear train 1a-1b-1c mounted in a housing 2. Reference X denotes the longitudinal axis of the turbine engine, which is the axis of rotation of its rotor and the gear reducer.

[0045] The innermost portion 1 a with respect to the axis X represents a sun gear in the form of a motor pinion, which is mounted on a turbine shaft (not shown) by a spline connection and which rotates at a determined speed ω1 .

[0046] Part 1b represents a planet carrier which supports, for example, three planetary gears meshing around the sun gear 1a. Here, the planet carrier is fixed to the static part of the turbine engine. The outer part 1c represents an outer ring gear which meshes with the planetary gears.

[0047] Here, the size ratios between the different elements are set so that the outer ring gear rotates at a speed ω2 that is reduced compared to the rotation speed of the sun gear 1 a , thereby rotating the planetary gears relative to the planetary carrier.

[0048] This brief description illustrates the fact that in such equipment, many parts are in contact with large relative movements and forces, which require large amounts of oil for lubrication and cooling.

[0049] The oil inlet, not shown in the figure, supplies oil to the gear reducer for lubrication. The oil is centrifugally driven through the various moving parts of the gear reducer (eg, teeth) and is driven radially outward by centrifugal action.

[0050] The shape of the gear ring 3 is designed to recover the oil that lubricates the gear reducer and guide the oil to outlet orifices 4, the path of the oil being indicated by arrows. These orifices 4 are advantageously located in the region of the maximum radius of the gear ring 3 in order to discharge the oil by centrifugal action. Moreover, these orifices are usually multiple and preferably evenly distributed around the circumference in a plane P perpendicular to the axis of rotation X.

[0051] An annular groove 5 surrounds the gear reducer in plane P and is configured to recover, by centrifugal action, oil ejected from the ring gear 3. This groove 5 is fixed to the housing 2 and therefore extends in a manner corresponding to the orifice 4, which leads to the above-mentioned disadvantages.

[0052] Figure 3 and Figure 4 An embodiment of a gear reducer 10 according to the invention is shown.

[0053] As mentioned above, the gear reducer 10 comprises a sun gear, planetary gears and a ring gear 9, the planetary gears being carried by a planet carrier, only the ring gear being partially visible in the drawing.

[0054] The gear reducer 10 is of planetary type, ie the sun gear and the ring gear 9 are rotatable, while the planet carrier is fixed.

[0055] The ring gear 9 is divided into two ring gear halves:

[0056] ■ Upstream gear ring half 9a, which consists of a rim 9aa and a mounting flange half 9ab. The rim 9aa is provided with the upstream spiral portion of the gear reducer tooth. The upstream spiral portion meshes with the upstream spiral portion of the planetary gear, and the upstream spiral portion of the planetary gear meshes with the upstream spiral portion of the sun gear;

[0057] ■ Downstream gear ring half 9b, which consists of a rim 9ba and a mounting flange half 9bb. On the rim 9ba is the downstream spiral portion of the gear reducer tooth. This downstream spiral portion meshes with the downstream spiral portion of the planetary gear, and the downstream spiral portion of the planetary gear meshes with the downstream spiral portion of the sun gear.

[0058] The mounting flange half 9ab of the upstream ring gear 9a and the mounting flange half 9bb of the downstream ring gear 9b form a mounting flange 9c of the ring gear.

[0059] Ring gear 9 is fixed to annular ring gear carrier 12 by engaging mounting flange 9c of ring gear and mounting flange 12a of ring gear carrier 12 (e.g. by means of a bolt assembly). Ring gear carrier 12 extends around ring gear half 9b and mounting flange 12a of ring gear carrier is applied to the downstream face of flange half 9bb.

[0060] The ring gear 9 is further secured to the fan shaft 13 using the same bolt assembly. The shaft 13 extends around the ring gear half 9a and includes a mounting flange 13a applied to the upstream side of the flange half 9ab.

[0061] As described and shown above in the prior art, the gear ring 9 comprises oil outlet orifices on its periphery. These orifices are formed by radial crescents 14 formed in the mutually facing faces of the flanges 9ab, 9bb, i.e., in the plane P, which here represents the bearing plane of these flanges.

[0062] The gear reducer 10 comprises an annular groove 16 (gutter) for recovering and guiding lubricating oil of the gear reducer 10 , the annular groove being installed around the gear reducer 10 , and in particular around the gear ring 9 of the gear reducer.

[0063] According to the invention, this groove 16 is offset in the axial direction relative to a plane P passing substantially through the centre of the toothed ring 9 . In the example shown, the groove is situated upstream of this plane P and comprises two annular parts, namely an annular chamber 18 and an annular duct 20 .

[0064] The gear reducer 10 further comprises an annular air guide 22, which is fixed to the ring gear 9. The air guide 22 is connected to the ring gear carrier 12. More precisely, the ring gear carrier 12 is formed as a single piece with the air guide 22, which extends radially toward the outside from the flange 12a.

[0065] The flow guide 22 extends around the crescent-shaped member 14 and is curved in an axial cross section, with the concave surface of the flow guide facing upstream and radially inward.

[0066] In the example shown, the flanges 13a, 12a and the flange halves 9ab, 9bb have an outer diameter D1, and the flow guide 22 extends between a minimum diameter D1 and a maximum diameter D2. The flow guide 22 further extends axially from a downstream axial end of the flow guide, the downstream axial end being located downstream of the plane P, at the flange half 9bb or the flange 12a, to an upstream end being located upstream of the plane P, at the flange half 9ab or the flange 13a. Thus, the upstream end of the flow guide 22 extends around the flange 13a and radially away from the flange 13a.

[0067] The duct 20 is annular and comprises two coaxial annular walls, respectively an inner annular wall 20 a and an outer annular wall 20 b . The duct 20 and its walls 20 a , 20 b are centered on the axis X of the turbine engine and gear reducer 10 .

[0068] The walls 20a, 20b each generally have a truncated cone shape. The outer wall 20b includes an upstream end with a smaller diameter D3 and a downstream end with a larger diameter D4. D4 is greater than D2, and the downstream end of the wall 20b extends around the upstream end of the guide 22. The inner wall 20a includes an upstream end D5 with a smaller diameter and a downstream end with a larger diameter D6. D6 is greater than D1, and the downstream end of the wall 20a extends around the flange 13a and inside the upstream end of the guide 22.

[0069] The groove 16 is fixed, whereas the air guide 22 can rotate with the ring gear 9. Therefore, sufficient radial clearance is provided between the flange 13a and the wall 20a and between the air guide 22 and the wall 20b to enable the air guide to rotate relative to the ring gear.

[0070] The groove 16 is fixed to the stator of the turbine engine (for example, the above-mentioned casing 2) by means of a radial flange 16a. Figure 5 and Figure 6 As shown, the groove 16 can be regarded as having two sections, namely an upper section 16b and a lower section 16c. The upper section 16b has an angular range of about 180°, and, using the analogy of a clock dial, the upper section extends from 9 o'clock to 12 o'clock and from 12 o'clock to 3 o'clock. The lower section 16c also has an angular range of about 180°, and, using the analogy of a clock dial, the lower section extends from 9 o'clock to 6 o'clock and from 6 o'clock to 3 o'clock.

[0071] At the upper section 16b, the flange 16a is in the form of a series of regularly spaced radial lugs, each of which is perforated with an orifice for the passage of screws etc. In the lower section, the flange 16a is in the form of a radial edge which is continuous over 360° and comprises, at certain locations, in particular at the circumferential ends of the edge, orifices for the passage of screws.

[0072] The chamber 18 is annular and generally parallelepiped in axial section. The chamber comprises two radially oriented side walls (respectively upstream side wall 18a and downstream side wall 18b) and the two side walls are interconnected by cylindrical walls (respectively inner cylindrical wall 18c and outer cylindrical wall 18d). The chamber 18 defines an inner annular space which is divided into two parts (respectively inner part and outer part) by a perforated annular partition 24.

[0073] The upstream side wall 18a is continuous for 360°. Figure 5 and Figure 6 As shown, the axis of revolution Y of the upstream side wall is not aligned with the axis X, but is offset downward (or offset toward the 6 o'clock direction). This causes the upstream wall 18a to shift downward (or toward the 6 o'clock direction). For example, Figure 3 and Figure 4 The inner periphery of the wall 18a is shown near the axis 13 at 12 o'clock ( Figure 5 ), and at 6 o'clock near the outer periphery of flange 13a ( Figure 6 ).

[0074] The downstream side wall 18b is continuous for 360° and comprises an annular opening for fluid communication with the upstream end of the duct 20. The wall 18b is thus connected to the walls 20a, 20b of the duct 20. Moreover, by analogy with the wall 18a, the wall 18b is offset relative to the axis X ( Figure 3 and Figure 4 ). Figure 4 Wall 18b is shown merging with flange 16a.

[0075] The inner cylindrical wall 18c extends around the shaft 13 and also follows the same offset relative to the axis X ( Figure 3 and 4 ).

[0076] exist Figure 5 and Figure 6 The circular lines 180 visible in FIG. 1 represent the above-mentioned offsets of the inner cylindrical wall 18 c and the outer cylindrical wall 18 d of the chamber 18 , respectively.

[0077] The outer cylindrical wall extends around the shaft 13 and also follows the same offset relative to the axis X ( Figure 3 and 4 ). The outer wall 18d includes a radial opening 26 at 6 o'clock, which is configured for the flow and discharge of oil for recirculation.

[0078] The partition 24 is generally U-shaped in cross section and comprises a flat central portion perforated with oil gallery orifices 28 and two radial annular edges located at the axial ends of the partition. These edges are oriented radially towards the inside and are supported on the faces of the interior of the chamber 18 facing the side walls 18a, 18b. The partition 24 is also offset relative to the axis X and is aligned with the upstream end 20a of the inner wall on the upper half of the groove and with the upstream end of the outer wall 20b on the lower half of the groove. The plane in which the perforated central portion of the oil gallery orifices 28 of the partition 24 lies is substantially equidistant from the cylindrical inner wall 18c and the cylindrical outer wall 18d of the chamber 18, respectively.

[0079] The orifice 28 of the baffle 24 is calibrated. The function of the baffle is to slow down the velocity of the fluid, thereby avoiding the foaming effect caused by the excessive degassing velocity of the oil leaving the gear reducer. Thus, the oil collected in the chamber 18 is properly degassed, thereby improving the flow and capture of the oil.

[0080] In operation, the oil can be recovered in the following manner. The oil is sprayed onto the guide 22 through the crescent 14 and is immediately directed upstream toward the interior of the pipe 20. The oil flows from the rotating marker to the fixed marker. In the pipe 20, the oil maintains a certain speed and reaches the chamber 18. In the upper section 16c, the chamber 18 includes a U-shaped semi-annular groove or a semi-annular groove forming a U-shape, the opening of which is radially oriented toward the outside and is closed by the partition 24. The oil is received in the groove and flows through the partition 24 under the action of gravity, and then flows circumferentially to the circumferential end of the groove. In the lower section 16d, the chamber 18 includes a U-shaped semi-annular groove or a semi-annular groove forming a U-shape, the opening of which is radially oriented toward the inside and is closed by the partition 24. Oil is received in the groove and flows by gravity through the baffles 24 and then flows circumferentially to the lowest point of the groove where it can be recirculated through the openings 26 .

[0081] The partition 24 may extend continuously over 360°. Alternatively, the partition may be segmented and include at least two separate segments. These segments may overlap each other at their circumferential ends. Alternatively, these ends may be spaced apart, such as Figure 7 As shown, to facilitate the transition of the partitions between the above-mentioned grooves.

Claims

1. A planetary gear reducer (10) for an aircraft turbine engine, the planetary gear reducer comprising a rotatable sun gear, a rotatable ring gear (9) and planetary gears, the planetary gears meshing with the rotatable sun gear and the rotatable ring gear and carried by a planet carrier intended to be fixed to a stator, the planetary gear reducer further comprising an annular groove for recovering and guiding lubricating oil, the annular groove being mounted around the rotatable ring gear, characterized in that The planetary gear reducer further comprises an annular guide portion (22), the annular guide portion being fixed to the rotatable gear ring and being configured to guide radially outflowing oil toward the outside of the rotatable gear ring to the annular groove by means of centrifugal force, the annular guide portion protruding radially outward from the fixed flange, the annular guide portion having a free annular edge located radially outside the fixed flange, and the annular groove comprising: - an annular chamber (18) axially remote with respect to a central plane (P) passing through the centre of the rotatable ring gear, and - an annular duct (20), which is located at one side of the annular chamber and enters the annular chamber, and is configured to receive the oil guided by the annular guide portion and ensure that the oil flows to the annular chamber.

2. The planetary gear reducer (10) for an aircraft turbine engine according to claim 1, wherein: The annular chamber (18) defines a first upper semicircular groove having a U-shaped axial cross-section and a second lower semicircular groove having a U-shaped axial cross-section. By analogy with a clock dial, the first upper semicircular groove extends from 9 o'clock to 12 o'clock, and from 12 o'clock to 3 o'clock. By analogy with a clock dial, the second lower semicircular groove extends from 9 o'clock to 6 o'clock, and from 6 o'clock to 3 o'clock.

3. The planetary gear reducer (10) for an aircraft turbine engine according to claim 2, wherein: The first upper semicircular groove includes a bottom defined by an inner cylindrical wall (18c) of the annular chamber (18), and the second lower semicircular groove includes a bottom defined by an outer cylindrical wall (18d) of the annular chamber.

4. The planetary gear reducer (10) for an aircraft turbine engine according to claim 3, wherein: The outer cylindrical wall (18d) comprises radial openings (26) for draining oil.

5. A planetary gear reducer (10) for an aircraft turbine engine according to claim 3 or 4, wherein: The inner cylindrical wall (18c) and the outer cylindrical wall (18d) have axes (Y) that are not aligned with each other and / or with the longitudinal axis (X) of the planetary gear reducer.

6. A planetary gear reducer (10) for an aircraft turbine engine according to any one of claims 2 to 4, wherein: The first upper semicircular groove is connected to a radially inner annular wall (20a) forming a part of the annular duct (20), and the second lower semicircular groove is connected to a radially outer annular wall (20b) forming a part of the annular duct.

7. A planetary gear reducer (10) for an aircraft turbine engine according to any one of claims 1 to 4, wherein: A perforated annular baffle (24) is housed in the annular chamber (18) and is configured to degas the oil.

8. A planetary gear reducer (10) for an aircraft turbine engine according to any one of claims 2 to 4, wherein: The first upper semicircular groove is connected to a radially inner annular wall (20a) forming a part of the annular duct (20), and the second lower semicircular groove is connected to a radially outer annular wall (20b) forming a part of the annular duct, wherein a perforated annular baffle (24) is accommodated in the annular chamber (18) and is configured to degas the oil, the perforated annular baffle (24) comprising a first section and a second section, the first section extending into the first upper semicircular groove and located at the radially inner annular wall (20a), and the second section extending into the second lower semicircular groove and located at the radially outer annular wall (20b).

9. An aircraft turbine engine comprising a planetary gear reducer (10) for an aircraft turbine engine according to any one of claims 1 to 8.

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