Mechanical reduction gear for an aircraft turbine engine

Abstract

The invention relates to a mechanical reduction gear (210) for an aircraft turbine engine, this reduction gear (210) including: - a sun gear (218) connected to a first shaft (A1) provided with a wheel (216), - a ring gear (222) mounted around the sun gear (218), - planet gears (220) mounted between the sun gear (218) and the ring gear (222), - a planet carrier (224) which carries the planet gears (220) and is connected to a second shaft (A2), - at least one torque input pinion (212) which is meshed with the wheel (216), - at least one apparatus (230) including a rotary shaft (232) provided with a pinion (234) which is meshed with gear teeth (236, 236', 236''), characterised in that the gear teeth (236, 236', 236'') are carried by one of the elements selected from the planet carrier (224) and the second shaft (A2).

Description

[0001] DESCRIPTION

[0002] TITLE: MECHANICAL REDUCER FOR AN AIRCRAFT TURBOMACHINE

[0003] Technical field of the invention

[0004] The present invention relates to a mechanical reducer for an aircraft turbomachine, as well as to an aircraft turbomachine comprising such a reducer. The turbomachine is for example a turboprop.

[0005] Technical background

[0006] The technical background includes in particular documents EP-A1 - 0 172 104, US-A1 -2021 / 371120, CN-U211 943 724, CN-A-116 767 498 and US-B2-11 104 430.

[0007] 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.

[0008] Aircraft equipped with turboprop engines are generally equipped with a mechanical reducer (PGB = Propeller Gear Box) allowing the rotation speeds between the turbine and the propeller to be adapted while generating an offset between the propeller rotation axis and the turbine rotation axis. This offset, also called "Offset", allows for good integration of the air intake under this reducer.

[0009] In order to improve the performance and efficiency of these turboprops during certain flight phases (takeoff, taxiing, etc.), several solutions are possible. One of these solutions consists of hybridizing the turboprop by adding an electric machine (in engine mode) to the gearbox in order to provide additional power during the relevant flight phases. It is also possible to use this electric machine (in generator mode) to recover energy during certain flight phases. There are several gearbox architectures. In the state of the art, gearboxes are of the planetary type with offset or epicyclic with offset. There are also so-called "compound" architectures.

[0010] - On an offset planetary reducer, the planet carrier is fixed and the crown constitutes the output shaft of the device which rotates in the opposite direction to the solar.

[0011] - On an epicyclic reducer, the crown is fixed and the planet carrier constitutes the output shaft of the device which rotates in the same direction as the solar.

[0012] - In a compound reducer, no element is fixed in rotation and the power is divided into two parallel lines. The output wheel rotates in the same direction as the input pinion.

[0013] An epicyclic offset type reducer 10 is illustrated in Figure 1. This reducer 10 comprises a pinion 12 of an input line 14 formed by an electric motor M or an output shaft of a turbine. This pinion 12 meshes with a wheel 16 which itself drives a central pinion called sun gear 18 meshing with pinions called satellites 20 which are themselves engaged with a crown 22. The satellites 20 are held by a frame called planet carrier 24. The sun gear 18, the crown 22 and the planet carrier 24 are planetary gears because their axes of revolution coincide with the longitudinal axis X of the propeller 26 which forms an output line 28. The satellites 20 have different axes of revolution Y and equally distributed on the same operating diameter around the axis of the planetary gears. These axes Y are parallel to the longitudinal axis X.

[0014] A compound type reducer 110 is illustrated in Figure 2. This reducer 110 comprises a pinion 112 of an input line 114 formed by an electric motor M or an output shaft of a turbine. This pinion 112 meshes with a first set of teeth 130 of two intermediate pinions 132 (called idlers) which take power. The intermediate pinions 132 then drive an output line 128 via a second set of teeth 134 of the intermediate pinions 132. By varying the number of teeth of the teeth 130, 134 of the pinions 132, it is possible to obtain a speed reduction ratio between the input line 114 and the output line 128 formed by the propeller 126.

[0015] Gearboxes can be composed of one or more meshing stages. This meshing is ensured in different ways such as by contact, friction or even magnetic fields. There are several types of contact meshing such as straight, helical or herringbone teeth.

[0016] A solution for integrating an electric machine into a mechanical reducer was proposed in document FR-A1 -3 073 569. This type of integration is viable as long as the level of electrical power required remains moderate. Indeed, the more powerful the electric machine, the more its volume increases, which can significantly limit its integration within the reducer.

[0017] In order to hybridize turboprop engines, it is necessary to add one or more electrical machines to inject power into the engine via the gearbox. In addition, it is necessary to integrate power extraction systems into the gearbox to operate accessories. Generally speaking, it is therefore necessary to equip the gearbox with equipment or accessories that include shafts that must be driven by the gearbox's moving parts. However, integration constraints make this approach difficult.

[0018] The invention provides a solution to this problem by allowing equipment, such as electrical machines or accessories, to be integrated into or onto the reducer.

[0019] Summary of the invention

[0020] The invention relates to a mechanical reducer for an aircraft turbomachine, this reducer comprising:

[0021] - a sun gear centered on a first axis and mobile in rotation around the first axis, this sun gear being connected to a first shaft (of the reducer) equipped with a wheel, - a crown mounted around the sun gear and the first axis, this crown being fixed, and

[0022] - satellites mounted between the sun and the crown and meshed with the sun and the crown, the satellites having second axes of rotation parallel to the first axis,

[0023] - a planet carrier which carries the satellites and which is mobile in rotation around the first axis, this planet carrier being connected to a second shaft (of the reducer),

[0024] - at least one torque input pinion which is meshed with said wheel and which is rotatable about a third axis parallel to the first axis, and

[0025] - at least one piece of equipment comprising a rotating shaft equipped with a pinion which is meshed with a set of teeth, characterized in that said set of teeth is carried by one of the elements chosen from the planet carrier and the second shaft.

[0026] The invention thus proposes to drive the shaft of the equipment or of each equipment by means of a toothing which is carried by one of the moving elements of the reducer.

[0027] Several configurations are possible. In a first configuration, it is the planet carrier that includes a drive toothing for the shaft of the or each piece of equipment. In this case, the equipment could, for example, be located on one side of the satellites, and in particular on the side of the propeller driven by the reduction gear in the case of a turboprop.

[0028] According to another configuration, it is the second shaft which includes a toothing for driving the shaft of the or each piece of equipment.

[0029] In this latter configuration, the equipment could, for example, be located on another side of the satellites, and in particular on the side opposite the propeller driven by the reducer in the case of a turboprop.

[0030] The solution proposed below is compatible with a multi-stage reducer. It is compatible with a reducer whose planet carrier is mobile in rotation, as is the case with an epicyclic reducer. It is also compatible with straight, helical or herringbone teeth. It is compatible with any type of planet carrier, and in particular with a single-piece planet carrier or a cage and cage carrier type. It is also compatible with any type of bearing, whether it is composed of rolling elements, a hydrodynamic bearing, etc.

[0031] The reducer according to the invention may comprise one or more of the following characteristics, taken in isolation from one another, or in combination with one another:

[0032] - said toothing is cylindrical or truncated conical.

[0033] - said toothing has an average diameter which is less than the diameter of a circumference passing through said second axes;

[0034] - the planet carrier comprises a tubular section which comprises internal splines for coupling to the second shaft, said teeth being carried by the planet carrier and extending in a plane perpendicular to the first axis which passes through this tubular section and / or which is connected to this tubular section.

[0035] - said at least one piece of equipment is located radially outside this tubular section;

[0036] - the planet carrier is formed from a single piece with an annular web which includes said teeth at its external periphery;

[0037] - the reducer further comprises a front casing to which said crown is fixed, this front casing comprising at least one housing for mounting said at least one piece of equipment;

[0038] - the shaft of said at least one piece of equipment has an axis of rotation which is parallel to said first axis or which is inclined relative to this first axis;

[0039] - said teeth are carried by the second shaft and are located at a longitudinal end of this shaft;

[0040] - said toothed wheel is located between a first plane perpendicular to the first axis and passing through the satellites, and a second plane perpendicular to the first axis and passing through said toothing; - the second shaft is formed from a single piece with an annular web which includes said toothing at its external periphery;

[0041] - the shaft of said at least one equipment has an axis of rotation which is parallel to the first axis or which is located in a plane perpendicular to the first axis;

[0042] - the number of said equipment is between 1 and 6, and preferably between 2 and 5, each of these equipments comprising a rotating shaft equipped with a pinion which is meshed with said teeth.

[0043] The invention further relates to a turbomachine, in particular for an aircraft, comprising at least one reduction gear as described above and at least one propeller coupled to the second shaft of said at least one reduction gear. This turbomachine is, for example, a turboprop.

[0044] Advantageously, said at least one propeller comprises variable-pitch blades connected to a system for changing the pitch of each of these blades, this system being mounted coaxially in the extension of the second shaft.

[0045] Brief description of the figures

[0046] Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which:

[0047] [Fig.1] Figure 1 is a schematic view of an epicyclic mechanical offset reducer,

[0048] [Fig.2] Figure 2 is a schematic view of a compound reducer,

[0049] [Fig.3] Figure 3 is a schematic axial sectional view of a turboprop-type turbomachine,

[0050] [Fig.4] Figure 4 is a schematic axial sectional view of a mechanical reducer according to a first embodiment of the invention,

[0051] [Fig.5] Figure 5 is a schematic perspective view of certain elements of the reducer of Figure 4,

[0052] [Fig.6] Figure 6 is another schematic perspective view of certain elements of the reducer of Figure 4, [Fig.7] Figure 7 is a view similar to that of Figure 5 and illustrates an alternative embodiment of the invention,

[0053] [Fig.8] Figure 8 is a view similar to that of Figure 6 and illustrates the same variant as Figure 7,

[0054] [Fig.9] Figure 4 is a schematic axial sectional view of a mechanical reducer according to another alternative embodiment of the invention, and

[0055] [Fig.10] Figure 10 is another schematic perspective view of the reducer of Figure 9.

[0056] Detailed description of the invention

[0057] Figures 1 and 2 have been described in the above.

[0058] Figure 3 illustrates an aircraft turbomachine, and in particular an aircraft turboprop 1, the aircraft being able to be for example an airplane or a helicopter.

[0059] In a known manner, the turboprop 1 comprises a casing 2, a gas turbine 3 comprising a turbine shaft 4, a propeller 26 comprising a propeller shaft 5, and a reduction gear 210 configured, on the one hand, to be driven by the turbine shaft 4 at a first speed and, on the other hand, to drive the propeller shaft 5 at a second speed lower than the first speed. In this example, the turbine shaft 4 is rotated at a high speed of the order of 20,000 to 35,000 revolutions per minute while the propeller shaft 5 is rotated at a reduced speed of the order of 1000 to 2500 revolutions per minute. The propeller shaft 5 is connected to the propeller 26, 126.

[0060] The reducer 210 makes it possible to drive the propeller 26, 126 in rotation at an optimum speed to allow the movement of the aircraft on which the turboprop 1 is mounted.

[0061] The present invention proposes a reducer 210, embodiments of which are illustrated in Figures 4 and following.

[0062] A first embodiment of the reducer 210 is illustrated in Figures 4 to 6 and comprises:

[0063] - a sun 218 centered on a first axis X and mobile in rotation around this first axis X, - a crown 222 mounted around the sun 218 and the first axis X, and

[0064] - satellites 220 mounted between the sun gear 218 and the crown gear 222 and meshed with the sun gear 218 and the crown gear 222.

[0065] The sun gear 218 is connected to a first shaft A1 which is equipped with a wheel 216, as is the case in an offset type reducer. In the example shown, the sun gear 218 comprises an external toothing 218a and is located at a longitudinal end of the shaft A1 whose opposite longitudinal end is connected to the wheel 216.

[0066] The sun gear 218 may be formed in a single piece with the shaft A1, that is to say that its teeth 218a are directly formed on the shaft A1. In the example shown, the sun gear 218 is on the contrary attached to the shaft A1. The sun gear 218 comprises internal splines 218b configured to cooperate with complementary external splines of the shaft A1 so that the sun gear is integral in rotation with the shaft A1.

[0067] The wheel 216 or its teeth 216a could also be formed in one piece with the shaft A1. In the example shown, however, the wheel 216 comprises internal splines 216b configured to cooperate with complementary external splines of the shaft A1 so that the wheel 216 is integral in rotation with the shaft A1 and the sun 218.

[0068] The toothing 216a of the wheel 216 is meshed with an input pinion 212, that is to say a pinion of an input line.

[0069] The shaft A1 can be rigid or on the contrary have a certain flexibility and therefore have a capacity for deformation, in particular in the radial direction.

[0070] The crown 222 is fixed in this application of the epicyclic reducer type. The crown 222 may thus comprise an annular flange 222a extending radially outwards and configured to be fixed to a similar flange 223a of a front casing 223. This front casing 223 extends around the axis X and a portion of the reducer 210. The flange 222a is further fixed to the flange 2a of the casing 2 of FIG. 3. The flange 223a of the front casing 223 is located at a first longitudinal end of the front casing 223, and its opposite longitudinal end carries at least one bearing 225 for guiding the rotation of a second shaft A2.

[0071] In the example shown, the front casing 223 has an annular shape around the axis X and comprises a cylindrical portion 223b carrying the flange 223a, and a frustoconical portion 223c which flares from the guide bearing 225 to the cylindrical portion 223b.

[0072] The satellites 220 have second axes of rotation Y parallel to the first axis X and are carried by a planet carrier 224 which is rotatable around the first axis X and which is connected to the second shaft A2 which is the propeller shaft 5 of figure 3.

[0073] The planet carrier 224 may be connected to the shaft A2 by splines 224a, as in the example shown. The planet carrier 224 comprises several physical axes 224b centered on the Y axes and around which the satellites 220 are mounted. The satellites 220 may be guided in rotation on these physical axes 224b by ball, roller or plain bearings 227.

[0074] The planet carrier 224 comprises a portion 224c comprising the physical axes 224b and further comprises a tubular section 224d comprising the splines 224a.

[0075] The shaft A2 comprises a section A21 which is located on one side of the planet carrier 224, that is to say on the side of the propeller 26, 226. The shaft A2 further comprises an axial extension A22 which passes through the planet carrier 224 and passes on its opposite side to the inside of the shaft A1 and the wheel 216. The shaft A2 is tubular for the passage of auxiliary equipment in the axial direction through it. The propeller 26, 226 is for example equipped with a system 229 for changing the pitch of its variable-pitch blades (of the PCU type). This system 229 can be located on the side of the wheel 216 and connected for example by oil pipes which axially pass through the shaft A2 to an actuator located on the side of the propeller 26, 226. The reducer 210 further comprises at least one piece of equipment 230 comprising a rotating shaft 232 equipped with a pinion 234 which is meshed with a toothing 236.

[0076] The equipment 230 or each equipment is chosen for example from an electric machine, a pump, etc.

[0077] In the first embodiment shown in Figures 4 to 6, the toothing 236 is carried by the planet carrier 224.

[0078] In the example shown, the toothing 236 is cylindrical.

[0079] The toothing 236 may have an average diameter D1 which is less than the diameter D2 of a circumference passing through the second axes Y.

[0080] In the example shown, the planet carrier 224 is formed from a single piece with an annular web 238 which includes the toothing 236 at its external periphery.

[0081] The web 238 here extends radially outwards from the tubular section 224d of the planet carrier 224. The toothing 236 is thus located in a plane P1 perpendicular to the first axis X which passes through this tubular section 224d.

[0082] Figure 4 shows a piece of equipment 230 driven by the toothing 236 and Figures 5 and 6 show two pieces of equipment 230 driven by this toothing. The shafts 232 of these pieces of equipment 230 here have axes of rotation parallel to the X axis.

[0083] In the example shown, the shafts 232 of the equipment 230 are coupled to the teeth 236 by means of attached pinions 234, but these pinions 234 could alternatively be formed in a single piece on these shafts 232.

[0084] The equipment 230 is located radially outside the tubular section 224d of the planet carrier 224.

[0085] In the example shown in Figure 4, the front casing 223 comprises at least one housing 240 for mounting the equipment 230. It is understood that the front casing 223 may comprise a number of housings 240 equal to the number of equipment 230 which is two in Figures 5 and 6. The or each housing 230 may have a generally cylindrical or parallelepiped shape and be located at the level of the frustoconical portion 223c of the front casing 223. The or each housing 240 opens into the annular cavity defined by the front casing 223 around the planet carrier 224.

[0086] The variant embodiment of figures 7 and 8 differs from the previous embodiment in particular in that the toothing 236 of the planet carrier 224 is frustoconical.

[0087] Furthermore, the shafts 232 of the equipment 230 have axes of rotation which are inclined relative to the X axis.

[0088] In the example shown, the number of devices 230 is three.

[0089] Another alternative embodiment of the reducer 210 is illustrated in Figures 9 and 10. The elements of the reducer 210 already described in the above are designated by the same references.

[0090] In this variant, there is a toothing 236” for driving a shaft 232 of at least one piece of equipment 230 which is carried by the wheel 216, and a toothing 236' for driving a shaft 232 of at least one other piece of equipment 230 which is carried by the second shaft A2.

[0091] In the example shown, the 236” toothing is cylindrical and the 236' toothing is conical.

[0092] The 236” toothing may have an average diameter D3 which is greater than or equal to the diameter D2 of a circumference passing through the second Y axes. The 236' toothing may have an average diameter D4 which is less than or equal to the diameter D2.

[0093] In the example shown, the toothing 236” is the main toothing 216a of the wheel 216. It is therefore understood that the wheel 216 is coupled by its main toothing 216a both to the input pinion 212, and to the shaft 232 of the equipment 230 or of each equipment 230. The shaft 232 coupled to the toothing 216a of the wheel 216 has an axis of rotation parallel to the axis X in the example shown. In the example shown, the toothing 236' is located at a longitudinal end of the second shaft A2.

[0094] The toothed wheel 216 can be located between a first plane P2 perpendicular to the first axis X and passing through the satellites 220, and a second plane P3 perpendicular to the first axis X and passing through the teeth 236'.

[0095] The second shaft A2 may be formed in one piece with an annular web 238 which includes the teeth 236' at its outer periphery.

[0096] There are here several pieces of equipment 230 (here between 1 and 6, and preferably between 2 and 5) driven by the teeth 236' and which are distributed around the axis X. This number depends in particular on the available space and may be greater than 6. The axes of the shafts 232 of these pieces of equipment 230 may all be oriented radially and contained in the same plane P4 perpendicular to the axis X. As a variant, one or more of the pieces of equipment 230 may have its shaft 232 which has an axis of rotation parallel to the axis X.

[0097] Figures 9 and 10 show that the system 229 for changing the pitch of the blades of the propeller 26, 226 is mounted coaxially in the extension of the second shaft A2, as mentioned above.

[0098] In the example shown, the equipment 230 is distributed around the X axis and this system 229.

[0099] The present invention provides several advantages such as:

[0100] - a reduction and optimization of the size of the reducer,

[0101] - a reduction in the mass of the reducer,

Claims

CLAIMS 1. Mechanical reducer (210) for an aircraft turbomachine, this reducer (210) comprising: - a solar (218) centered on a first axis (X) and mobile in rotation around the first axis (X), this solar (218) being connected to a first shaft (A1) equipped with a wheel (216), - a crown (222) mounted around the sun (218) and the first axis (X), this crown (222) being fixed, and - satellites (220) mounted between the sun (218) and the crown (222) and meshed with the sun (218) and the crown (222), the satellites (220) having second axes of rotation (Y) parallel to the first axis (X), - a planet carrier (224) which carries the satellites (220) and which is rotatable around the first axis (X), this planet carrier (224) being connected to a second shaft (A2), - at least one torque input pinion (212) which is meshed with said wheel (216) and which is rotatable about a third axis (Z) parallel to the first axis (X), and - at least one piece of equipment (230) comprising a rotating shaft (232) equipped with a pinion (234) which is meshed with a toothing (236, 236', 236”), characterized in that said toothing (236, 236', 236”) is carried by one of the elements chosen from the planet carrier (224) and the second shaft (A2).

2. Reducer (210) according to claim 1, wherein said toothing (236, 236', 236”) is cylindrical or frustoconical toothing.

3. Reducer (210) according to claim 1 or 2, wherein said toothing (236, 236', 236”) has an average diameter (D1, D4) which is less than the diameter (D2) of a circumference passing through said second axes (Y).

4. Reducer (210) according to one of claims 1 to 3, in which the planet carrier (224) comprises a tubular section (224d) which comprises internal splines (224a) for coupling to the second shaft (A2), said teeth (236) being carried by the planet carrier (224) and extending in a plane (P2) perpendicular to the first axis (X) which passes through this tubular section (224d) and / or which is connected to this tubular section.

5. Reducer (210) according to claim 4, wherein said at least one piece of equipment (230) is located radially outside this tubular section (224d).

6. Reducer (210) according to one of claims 1 to 5, in which the planet carrier (224) is formed in a single piece with an annular web (238) which comprises said toothing (236) at its external periphery.

7. Reducer (210) according to one of claims 1 to 6, further comprising a front casing (223) to which said crown (222) is fixed, this front casing (223) comprising at least one housing (240) for mounting said at least one piece of equipment (230).

8. Reducer (210) according to one of claims 1 to 7, wherein the shaft (232) of said at least one equipment (230) has an axis of rotation which is parallel to said first axis (X) or which is inclined relative to this first axis (X).

9. Reducer (210) according to claim 1 or 2, in said toothing (236) is carried by the second shaft (A2) and is located at a longitudinal end of this shaft (A2).

10. Reducer (210) according to claim 1, 2 or 9, wherein said toothed wheel (216) is located between a first plane (P2) perpendicular to the first axis (X) and passing through the satellites (220), and a second plane (P3) perpendicular to the first axis (X) and passing through said toothing (236').

11. Reducer (210) according to claim 1, 2, 9 or 10, wherein the second shaft (A2) is formed in one piece with an annular web (238) which comprises said toothing (236') at its external periphery.

12. Reducer (210) according to one of claims 1, 2, 9, 10 or 11, wherein the shaft (232) of said at least one equipment (230) has an axis of rotation which is parallel to the first axis (X) or which is located in a plane (P4) perpendicular to the first axis (X).

13. Reducer (210) according to one of the preceding claims, in which the number of said equipment (230) is between 1 and 6, and preferably between 2 and 5, each of these equipment (230) comprising a rotating shaft (232) equipped with a pinion (234) which is meshed with said teeth (236, 236', 236”).

14. Turbomachine (1), in particular for an aircraft, comprising at least one reduction gear (210) according to one of the preceding claims and at least one propeller (26, 226) coupled to the second shaft (A2) of said at least one reduction gear (210).

15. Turbomachine (1) according to the preceding claim, in which said at least one propeller (26, 226) comprises variable-pitch blades connected to a system (229) for changing the pitch of each of these blades, this system (229) being mounted coaxially in the extension of the second shaft (A2).

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