Oil supply device for a mechanical reduction gear of an aircraft turbine engine

Abstract

The invention relates to an oil supply device (22) for a mechanical reduction gear (10) of an aircraft turbine engine (1), the device (22) comprising an impeller (24) which has a generally annular shape around a first axis (X) and which comprises: - a first annular groove (26) opening radially inwards for supplying oil to the device (22) by spraying oil into the groove (26); - first inner channels (28) extending at least partially radially in relation to the first axis (X) and comprising radially inner ends (28a) which are connected to the first groove (26) and radially outer ends (28b) which are connected to oil supply ports (30), characterised in that it further comprises: - filtration strainers (40) housed in the first inner channels (28).

Description

[0001] DESCRIPTION

[0002] TITLE: OIL SUPPLY DEVICE FOR A MECHANICAL REDUCTION GEAR ON AN AIRCRAFT TURBOMACHINE

[0003] Technical field of the invention

[0004] The present invention relates to an oil supply device for a mechanical reducer of an aircraft turbomachine, as well as a mechanical reducer comprising such a device.

[0005] Technical background

[0006] The role of a mechanical reducer is to modify the speed ratio and torque between the input shaft and the output shaft of a mechanism.

[0007] Newer generations of turbofan engines, particularly those with a high bypass ratio, incorporate a mechanical gearbox to drive the fan shaft. Typically, the gearbox's purpose is to transform the high rotational speed of the power turbine shaft into a slower rotational speed for the fan shaft.

[0008] 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 the planet carrier. The sun gear, ring gear, and planet carrier are planetary gears because their axes of revolution coincide with the longitudinal axis of the turbomachine. The planet gears each have a different axis of revolution and are evenly spaced on the same operating diameter around the axis of the planet gears. These axes are parallel to the longitudinal axis of the turbomachine.

[0009] There are several gearbox architectures. In state-of-the-art turbomachinery, gearboxes are of the planetary or epicyclic type. In other similar applications, there are differential or compound architectures. In a planetary gearbox, the planet carrier is fixed, and the ring gear forms the output shaft of the device, rotating in the opposite direction to the sun.

[0010] - On an epicyclic reducer, the ring is fixed and the planet carrier constitutes the output shaft of the device which rotates in the same direction as the solar.

[0011] - On a differential gearbox, no element is fixed in rotation. The ring rotates in the opposite direction to the solar and satellite carrier.

[0012] Gearboxes can consist of one or more meshing stages. This meshing is achieved in various ways, such as by contact, friction, or magnetic fields.

[0013] There are several types of contact meshing such as with straight or herringbone teeth.

[0014] Planetary gear reducers, in particular, have the advantage of offering significant speed reduction ratios in compact sizes. However, like differential gearboxes, they have the disadvantage of having planetary gears that rotate around the axis of rotation of the gearbox's drive shaft, which is coaxial with the planetary gear. They therefore require devices to transfer oil from a reservoir and pump located in a fixed frame of reference to lubrication systems that follow the rotational movement of the planetary gear axes around the drive shaft. To address this issue, commonly used devices include rotary joint systems.

[0015] These systems have the disadvantages of being quite bulky and prone to wear that is incompatible with the required lifespan of aircraft engines, thus impacting engine maintenance. Finally, these gearboxes are difficult to integrate with a flexible turbomachine structure, recommended, for example, to compensate for the loss or breakage of a fan blade, or with a modular design to facilitate engine assembly.

[0016] In order to remedy these drawbacks, the applicant has already proposed, in applications W0-A1-2010 / 092263, FR-A1-2987 416, W0-A1-2019 / 16463 and WO-A1-2019 / 16491, lubrication devices without rotating seals. These devices include oil jets connected to an oil circuit of the fixed reference frame and designed to spray oil into an annular groove of an oil supply device (referred to as a "wheel" or "distributor") of the rotating reference frame. The oil supply device is rotationally fixed to the planet carrier and confines the oil sprayed by the jets, then directs it by centrifugal force to the lubrication means for the planetary bearings, in particular.

[0017] These devices thus greatly improve the reliability of the gearbox lubrication system as well as its maintenance.

[0018] Among the gearbox components lubricated by the oil supply system are the planetary gear bearings. These bearings support the load exerted on the planetary gears. When the bearings are of the plain or hydrodynamic type, they must be supplied with a certain amount of oil because without oil, the bearings will not function correctly. In a lubrication system of this type, there is a loss of fluid continuity between the supply pump and the components supplied by this system. Solid particles (from worn parts within the gearbox) can enter the lubrication system by penetrating its internal annular groove. These particles can mix with the oil and wear down the components supplied by the system, such as the planetary gear bearings.

[0019] The invention provides a simple, efficient, and economical solution to this problem.

[0020] Summary of 'invent on

[0021] The invention relates to an oil supply device for a mechanical gearbox of an aircraft turbomachine, this device comprising a wheel which has a generally annular shape around a first axis and which includes: - a first annular groove opening radially inwards for supplying oil to the device by projecting oil into the groove, - first internal channels extending at least partly radially with respect to the first axis and having radially internal ends connected to the first groove and radially external ends connected to oil supply ports,

[0022] characterized in that it further comprises:

[0023] - filtration strainers housed in the radially internal ends of the first internal channels.

[0024] In this application, the term "filter screen" means a filtration device which is attached and fixed in the wheel for the purpose of filtering oil, and in particular for filtering oil by passing the oil through a filter cloth.

[0025] The invention proposes integrating filter screens into the centrifugal impeller to filter the oil of larger particles, for example those with an average size of 50 microns or more. The screens capture the particles before they enter the parts lubricated by the device.

[0026] The proposed solution is compatible with single-stage or multi-stage gearboxes. It is also compatible with epicyclic or differential gearboxes. It is also compatible with spur, helical, or herringbone gears. It is also compatible with all types of planet carriers, whether monobloc or cage-type. It is compatible with all types of planetary bearings, whether composed of rolling elements, hydrodynamic bearings, etc.

[0027] The device according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0028] - the filtration strainers are located in the radially internal ends of the first internal channels;

[0029] - each of the filter strainers has an elongated shape along a second axis which extends radially with respect to the first axis;

[0030] - each of the filter screens includes a tubular wall centered on the second axis and formed by a filter cloth which is configured to allow oil to pass from the inside to the outside of the wall, and to retain particles having a size greater than a predetermined value; - each of the filter screens includes at one longitudinal end positioning fingers which extend radially outwards with respect to the second axis;

[0031] - the number of fingers is between 2 and 6, the fingers defining oil circulation passages between them;

[0032] - the fingers are evenly distributed around the second axis;

[0033] - the longitudinal end connected to the fingers has a flat shape extending in a plane perpendicular to the second axis, or a general convex shape in the form of a portion of a sphere centered on the second axis;

[0034] - the longitudinal end connected to the fingers is solid;

[0035] - the longitudinal end connected to the fingers is formed in one piece with said tubular wall;

[0036] - each of the filter strainers includes at one longitudinal end an external annular collar;

[0037] - the collar includes an external annular groove in which an annular sealing gasket is housed;

[0038] - the longitudinal end connected to the collar includes a female indentation centered on the second axis and configured to cooperate with a tool for mounting / dismounting the filter strainer;

[0039] - the filter strainers are held in the first internal channels by means of nuts which are screwed into threads of the first internal channels and which bear against the filter strainers, or by means of circlip-type locking rings which are mounted in the first internal channels and which bear against the filter strainers;

[0040] - the filter strainers are screwed directly into the first internal channels;

[0041] - the nuts or locking rings bear against the collars of the filter strainers;

[0042] - the filtration strainers include external threads for screwing into the first internal channels.

[0043] The present invention also relates to a mechanical reducer for an aircraft turbomachine, this reducer comprising: - a sun gear centered on an axis,

[0044] - a fixed corona extending around the axis and the sun,

[0045] - satellites mounted between the solar system and the corona and meshed with the solar system and the corona,

[0046] - a satellite carrier that supports the satellites and is mobile in rotation around the axis, and

[0047] - a device such as described above which is centered on the axis and which is fixed to the satellite carrier, the ports of the wheel opening into internal lubrication cavities of the satellite bearings.

[0048] The satellites are preferably guided in rotation by bearings, of the plain or hydrodynamic type. The internal cavities of the bearings are supplied with oil by the device in order to form oil films between the bearings and the satellites.

[0049] Brief description of the figures

[0050] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which:

[0051] [Fig.1] Figure 1 is a schematic half-view in axial cross-section of an aircraft turbomachine,

[0052] [Fig.2] Figure 2 is a half axial cross-sectional view of an epicyclic reducer, [Fig.3] Figure 3 is a schematic half axial cross-sectional view of an oil supply device according to the invention,

[0053] [Fig. 4] Figure 4 is a partial schematic perspective half view of an oil supply device according to the invention,

[0054] [Fig. 5] Figure 5 is a schematic half-view in axial cross-section of an oil supply device according to the invention, and shows an embodiment of a filtration strainer,

[0055] [Fig. 6] Figure 6 is a schematic perspective view of the filter strainer in Figure 5.

[0056] [Fig. 7] Figure 7 is a view similar to that of Figure 6 and illustrates one alternative embodiment of the filter strainer. [Fig. 8] Figure 8 is a view similar to that of Figure 6 and illustrates another alternative embodiment of the filter strainer.

[0057] [Fig.9] Figure 9 is a view similar to that of Figure 6 and illustrates another embodiment of the filter strainer,

[0058] [Fig. 10] Figure 10 is a view similar to that of Figure 6 and illustrates another embodiment of the filter strainer,

[0059] [Fig. 11] Figure 11 is a schematic perspective view of a filter strainer,

[0060] [Fig.12] Figure 12 is a schematic perspective view of another filter strainer.

[0061] Detailed description of the invention

[0062] Figure 1 shows a turbomachine 1 which includes, in a conventional manner, a blower propeller 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.

[0063] The high-pressure compressor 1b and the high-pressure turbine 1d are connected by a high-pressure shaft 2 and together form a high-pressure (HP) unit. 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) unit.

[0064] The blower propeller S is driven by a blower shaft 4 which is coupled to the BP shaft 3 by means of an epicyclic gear reducer 10 shown here schematically.

[0065] The reducer 10 is positioned in the front part of the turbomachine 1. A fixed structure schematically comprising, here, an upstream part 5a and a downstream part 5b is arranged to form an enclosure E1 surrounding the reducer 10.

[0066] This enclosure E1 is closed upstream by seals at a bearing that allows the passage of the blower shaft 4, and downstream by seals at the point where the BP shaft 3 passes through it. Referring to Figure 2, the gearbox 10 includes a ring gear 14 which is fixed via a ring carrier (not shown) to the fixed structure 5a, 5b with flexible means arranged to allow it to follow any movements of the blower shaft 4, for example, in certain degraded operating conditions. In a planetary gear system, the ring carrier consists of a more or less flexible part that drives the ring gear and a part held by bearings or bushings on which the blower is mounted. These fastening means are known to those skilled in the art and are not detailed here. A brief description can be found, for example, in FR-A1-2987416.

[0067] The gearbox 10 engages on one side with the BP shaft 3 via splines 7, which drive a planetary or solar gear 11, and on the other side with the fan shaft 4, which is attached to a planet carrier 13. Typically, the solar gear 11, whose axis of rotation X coincides with that of the turbomachine 1, drives a series of planetary gears or planets 12, which are evenly distributed around the circumference of the gearbox 10. The number of planets 12 is generally between three and seven. The planets 12 also rotate around the X axis of the turbomachine 1, except in the case of a planetary configuration where they rotate only around their axes of revolution, meshing with internal teeth of the ring gear 14, which is fixed to a stator of the turbomachine 1 via flanges 20 in the case of an epicyclic configuration, or fixed to a rotor of the turbomachine in the case of the planetary architecture.

[0068] Each of the satellites 12 rotates freely around a satellite axis / bearing 16 connected to the satellite carrier 13, using a bearing which can be plain, as shown in Figure 2, or a rolling element bearing (ball or roller bearings).

[0069] The rotation of the satellites 12 around their satellite axes 16, due to the interaction of their pinions with the teeth of the ring gear 14, causes the rotation of the satellite carrier 13 around the X-axis, and consequently that of the blower shaft 4 connected to it, at a rotational speed lower than that of the BP shaft 3. Figure 2 shows the oil supply to the gearbox 10 and its path within it. Arrows in Figure 2 indicate the path followed by the oil from, in this example, a buffer reservoir connected to the fixed structure of the turbomachine 1, to the pinions and bearings to be lubricated.

[0070] The lubrication device includes in particular a first part linked to the fixed structure and delivering the oil to the rotating parts of the reducer 10, and a supply device 22 rotating with the planet carrier 13 and receiving this oil in the case of a reducer qualified as "epicycloidal" (epicycloidal architecture commonly referred to as "planetary" in English-language literature).

[0071] The device 22 includes a wheel 24 which has a generally annular shape around the X axis and which comprises:

[0072] - at least one annular groove 26 opening radially inwards for supplying oil to the device 22 by spraying oil into the groove 26,

[0073] - the first internal channels 28 extending at least partly radially with respect to the X axis and having radially internal ends 28a connected to the groove 26 and radially external ends 28b connected to oil supply ports 30 of the reducer 10, these ports 30 opening for example in an axial direction.

[0074] The oil is projected into the throat 26 by one or more nozzles 34

[0075] The groove 26 supplies oil to the first channels 28 by centrifugation, the oil circulating in these channels 28 to the ports 30 for the purpose of lubricating the bearings of the satellites 12 in the example shown.

[0076] The first groove 26 could also be connected to other oil supply channels 36 for jets 38 for example, these jets 38 being located in the reducer 10 and intended to project oil onto gears.

[0077] Figures 3 to 12 illustrate several embodiments of the feeding device 22. Figure 3 shows half of an axial section of this device 22, the device 22 and its wheel 24 having a general annular shape around the axis X.

[0078] It is important to note that device 22 can take the general form:

[0079] - of a disc centered on this axis X, and having at its inner periphery the groove 26, the channels 28 extending inside the annular wall of the disc, or

[0080] - of a ring centered on the X axis and around which radially extend arms distributed around the X axis, the groove 26 being made in the ring and the channels 28 being formed inside the arms.

[0081] In figures 3 to 10, the elements already described above are designated by the same references.

[0082] Figures 3 and 4 show the general principle of the invention which consists of mounting filtration strainers 40 in the internal channels 28.

[0083] As in the example shown, the strainers 40 can be located in the radially internal ends 28a of the channels 28 to facilitate their assembly and accessibility in case of maintenance.

[0084] To accommodate the strainers 40, the ends 28a of the channels 28 can be enlarged. The ends 28a of the channels 28 may, in particular, include a cylindrical bore 60, one longitudinal end 60a of which opens into the groove 26, and the opposite longitudinal end 60b of which is connected to a cylindrical bearing surface 62 and is in fluidic communication with the remainder of the corresponding channel 28.

[0085] Figures 5 and 6 illustrate a first embodiment of a filter strainer 40 and figures 7 and following illustrate variants of the embodiment of the strainer 40.

[0086] Preferably, each of the filter screens 40 has an elongated shape along a Y axis which extends radially with respect to the X axis of the reducer 10. Each of the screens 40 includes a tubular wall 42 centered on the Y axis and formed by a filter cloth which is configured to allow oil to pass from the inside to the outside of the wall (see arrows in Figures 5 and 6), and to retain particles having a size greater than a predetermined value (for example 50μm).

[0087] The filter cloth includes, for example, a mesh of threads or fibers whose orifices are determined by the size of the particles to be retained.

[0088] The wall 42 defines an internal cavity which extends along the Y axis and which is closed at one longitudinal end 40a, and open at its opposite longitudinal end 40b.

[0089] The longitudinal end 40a can be solid. This longitudinal end 40a is preferably formed in one piece with the tubular wall 42. The end 40a and the wall 42 are preferably made of the same material.

[0090] Each of the filter strainers 40 can include at its closed longitudinal end 40a positioning fingers 44 which extend radially outwards with respect to the Y axis. The positioning fingers 44 are able to bear axially (with respect to the Z axis) on the aforementioned bearing surface 62, as seen in the drawings.

[0091] The number of fingers 44, for example, is between 2 and 6. It is 4 in figures 6 and 11, and 2 in figure 12.

[0092] The fingers 44 define oil circulation passages between them (see arrows in figures 5 and 6).

[0093] The 44 fingers are preferably evenly distributed around the axis, as illustrated in figures 5, 6 and 11.

[0094] The longitudinal end 40a of each strainer 40 connected to the fingers 44 may have a flat shape, as illustrated in figure 9, this flat shape extending in a plane perpendicular to the Y axis.

[0095] Alternatively, the longitudinal end 40a of each strainer 40 connected to the fingers 44 may have a general domed shape in a portion of a sphere centered on the Y axis, as illustrated in figures 5 to 8 and 10 to 12.

[0096] Each of the filter strainers 40 may include at its open longitudinal end 40b, opposite the fingers 44, an external annular collar 46.

[0097] The flange 46 may include an external annular groove 48 in which an annular sealing gasket 50 is housed (Figures 5 and 6). The flange 46 is adapted to cooperate with the end 60a of the bore 60 in order to center the strainer 40 in this bore 60. The gasket 50 is intended to be radially compressed between the bottom of the groove 48 and the internal cylindrical surface of the end 60a, in order to ensure a seal between the strainer 40 and the impeller and thus allow the oil to enter through the open longitudinal end 40b of the strainer 40 (see arrows in Figures 5 and 6).

[0098] The longitudinal end 40b may include a female recess 52 centered on the Y axis and configured to cooperate with a mounting / dismounting tool for the filter strainer 40 (figures 4 and 6).

[0099] The wall 42 preferably has an external diameter smaller than that of the flange 46. The wall 42 may have an external diameter smaller than or equal to that of the end 40a, as illustrated in the variants of Figures 7 to 10. The filter screens 40 can be retained in the channels 28 by means of nuts 54 which are screwed into threads of the channels 28 and which bear against the filter screens 40. These threads are located in the ends 60a of the aforementioned bores 60.

[0100] Alternatively, the strainers 40 could be retained in the channels 28 by means of circlip-type locking rings which are mounted in the channels 28 and which bear against the strainers 40.

[0101] Preferably, these nuts 54 or locking rings bear against the collars 46 of the strainers 40, as illustrated in figure 5.

[0102] Instead of nuts 54 or rings, the strainers 40 could be attached to the wheel themselves. The strainers 40 could, for example, have external threads for screwing into the channels 28. In yet another variant...

[0103] Preferably, the number of strainers 40 is equal to the number of channels 28 of the wheel, each of the channels 28 being equipped with a strainer 40.

Claims

DEMANDS 1. Oil supply device (22) for a mechanical gearbox (10) of an aircraft turbomachine (1), this device (22) comprising a wheel (24) which has a generally annular shape about a first axis (X) and which includes: - a first annular groove (26) opening radially inwards for supplying oil to the device (22) by spraying oil into the groove (26), - of the first internal channels (28) extending at least partly radially with respect to the first axis (X) and comprising radially internal ends (28a) connected to the first groove (26) and radially external ends (28b) connected to oil supply ports (30), characterized in that it further comprises: - filtration strainers (40) housed in the radially internal ends (28a) of the first internal channels (28).

2. Device (22) according to claim 1, characterized in that each of the filter strainers (40) has an elongated shape along a second axis (Y) which extends radially with respect to the first axis (X).

3. Device (22) according to claim 2, characterized in that each of the filter screens (40) comprises a tubular wall (42) centered on the second axis (Y) and formed by a filter cloth which is configured to allow oil to pass from the inside to the outside of the wall (42), and to retain particles having a size greater than a predetermined value.

4. Device (22) according to claim 2 or 3, characterized in that each of the filter strainers (40) comprises at a longitudinal end (40a) positioning fingers (44) which extend radially outwards with respect to the second axis (Y).

5. Device (22) according to claim 4, characterized in that the number of fingers (44) is between 2 and 6, the fingers (44) defining oil circulation passages between them.

6. Device (22) according to claim 4 or 5, characterized in that the fingers (44) are regularly distributed around the second axis (Y).

7. Device (22) according to any one of claims 4 to 6, characterized in that the longitudinal end (40a) connected to the fingers (44) has a flat shape extending in a plane perpendicular to the second axis (Y), or a general convex shape in the form of a portion of a sphere centered on the second axis (Y).

8. Device (22) according to any one of claims 2 to 7, characterized in that each of the filter strainers (40) comprises at a longitudinal end (40b) an external annular collar (46).

9. Device (22) according to claim 8, characterized in that the collar (46) comprises an external annular groove (48) in which an annular sealing gasket (50) is housed.

10. Device (22) according to claim 8 or 9, characterized in that the longitudinal end (40b) connected to the collar (46) comprises a female recess (52) centered on the second axis (Y) and configured to cooperate with a tool for mounting / dismounting the filter strainer (40).

11. Device (22) according to any one of the preceding claims, characterized in that the filter screens (40) are retained in the first internal channels (28) by means of nuts (54) which are screwed into threads of the first internal channels (28) and which bear against the filter screens (40), or by means of circlip-type locking rings which are mounted in the first internal channels (28) and which bear against the filter screens (40).

12. Device (22) according to claim 11, depending on any one of claims 7 to 10, characterized in that the nuts (54) or locking rings bear against the collars (46) of the filter strainers (40).

13. Device (22) according to any one of claims 1 to 10, characterized in that the filter strainers (40) comprise external threads for screwing into the first internal channels (28).

14. Mechanical gearbox (10) for an aircraft turbomachine (1), this gearbox comprising: - a solar (11) centered on an axis (X), - a fixed crown (14) extending around the axis (X) and the solar (11), - satellites (12) mounted between the solar element (11) and the corona (14) and meshed with the solar element (11) and the corona (14), - a satellite carrier (13) that supports the satellites (12) and is rotatable around the axis (X), and - a device (22) according to one of the preceding claims which is centered on the axis (X) and which is fixed to the satellite carrier (13), the ports (30) of the wheel (24) opening for example into internal lubrication cavities of the bearings of the satellites (12).

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