FR3138926A1 - High power density radial gear counter-rotating fan module for turbofan - Google Patents

Abstract

Counter-rotating fan module for X-axis turbofan 10, comprising a fan S, a counter-rotating radial reduction unit 50 and a fan S'; Said counter-rotating radial reducer group 50 comprising a module support 80 and a radial reducer 5, with coaxial shafts of axis X, with gears with concurrent axes, formed of; a subassembly SE2 composed of a ring 30 rotatably mounted around X, connected to said fan S; a subassembly SE2' composed of a crown CR 300 rotatably mounted around X, connected to said fan S'; and a subassembly SE1, comprising a plurality of satellites 22, equally distributed around X, with axis of rotation Y transverse to X, rotatably mounted on a planet carrier 20, comprising a central hub 20a; characterized in that said blowers S;S' are arranged on either side of said radial reducer 5, said module support 80, of axis of revolution of the gas turbomachine 2 of the turbofan 10. “Figure for the abstract: Figure 2”

Description

High power density radial gear counter-rotating fan module for turbofan

The present invention relates to the field of speed reducers for aircraft gas turbine engines, in particular for turbofan engines with a high bypass ratio.

A dual-flow turbofan or “turbofan” (in English), can be defined generally as a gas turbomachine, rotating, at least, a ducted fan or “fan” (in English), with a module of blower.
The new generations of turbofan engines with a high bypass ratio include a mechanical speed reducer connected coaxially between the turbomachine output shaft and the fan shaft. Usually, the speed reducer, or reduction gear, aims to transform the so-called fast rotation speed of the turbomachine shaft into a slower rotation speed for the shaft driving the fan, thus making it possible to optimize the rotation speed of the turbomachine while maintaining a suitable fan rotation speed. This makes it possible, among other things, to increase propulsion efficiency and reduce the noise level of the engine.

For such a turbofan engine, with a longitudinal axis of rotation is efficient.
However, an aircraft engine is an environment where the operating conditions and reliability requirements are extremely severe, and in such a turbofan engine comprising a reduction gear, the highly stressed gear teeth are among the most sensitive mechanical parts. of the motor.

To improve the reliability of such a turbofan reducer it is advantageous to use a reducer with coaxial shafts comprising gears with concurrent axes, that is to say a reducer composed of a pair of coaxial toothed wheels to the axis of rotation X of the turbofan, connected by a plurality of toothed pinions whose axes of rotation are substantially transverse to the longitudinal axis of rotation
This “radial” orientation of the toothed pinions relative to the axis of rotation

We know from the international publication WO2021 245180 A1 a high power density radial gearbox for turbofan engines which makes it possible to obtain both a reduction ratio and an optimized power density, corresponding to the needs of current turbofan engines.
Said radial gear reducer with concurrent axes of the aforementioned patent is a “split torque” type reducer composed of a plurality of internal force paths which divides the torque and allows maximized power density.
To do this, the plurality of force paths, made up of pairs of toothed pinions coupled in rotation, also called satellites, of axis of rotation Y, are equally distributed substantially transversely with respect to the axis of rotation X of the turbofan.

An advantage enabled by said high power density radial gearbox is the transverse orientation of said satellites relative to the axis of rotation X of the turbomachine.
In fact, this orientation of the gear links allows the reduction gear to operate on the non-rigid shaft line of a turbofan, due to possible misalignments of the axes of rotation of the different rotating parts constituting said line of shafts. As a result, said radial gearbox does not necessarily have to be attached in a flexible or “floating” manner to the fixed frame of the motor to absorb misalignments.

As specified in patent WO2021 245180 A1, another advantage enabled by said radial gearbox is the possibility of said satellites being able to rotate, i.e. a single fan, as detailed in a particular mode of the invention in the provisional national application FR2203341, or to simultaneously drive two fans in counter-rotation.

It is known to those skilled in the art that a pair of counter-rotating fans allows greater propulsion efficiency than a single fan rotating in one direction. Also, due to the strong current trend of research for a high-efficiency aircraft engine, it is advantageous that a reduction gear for a turbofan engine making it possible to optimize the speed of the turbomachine, also makes it possible to drive such counter-rotating fans. , as reliably as possible.
Therefore, a module of contra-rotating fans driven in rotation by the radial gearbox of patent WO2021 245180 A1 must therefore be proposed, as well as an example of attachment of said module to a gas turbomachine of an aircraft engine.

The energy performance and reliability of commercial aircraft engines having a constant need for improvement, the objective of the invention is to propose a variant of use of the radial reduction gear of the aforementioned patent, in which said reduction gear rotates two counter-rotating fans, in a fan module that can be used in a dual-flow turbofan, as well as an example of attaching said module to a gas turbomachine of an aircraft engine.

To do this, the invention concerns, according to its most general acceptance, a contra-rotating fan module for a turbofan, comprising two fans driven in contra-rotation by a radial gearbox according to the international publication WO2021 245180 A1, and the integration or the incorporation of such a fan module in a turbofan, with the aim of transferring the propulsion of said pair of contra-rotating fans, to an aircraft.

DESCRIPTION OF FIGURES
In these drawings:
- is a general view in half longitudinal section of an example of architecture of a dual-flow turbofan, incorporating a counter-rotating fan module according to the invention
- is a front detail view according to the
- is an exploded isometric detail view of a subassembly of the radial gearbox according to the
- is an exploded isometric view of a counter-rotating radial reduction unit of a fan module according to the
- is a front detail view in half longitudinal section of the counter-rotating fan module according to the invention

On the is shown the dual-flow turbofan 10 with a counter-rotating fan module according to the invention, which comprises from upstream to downstream, in the direction of flow of the flows (A;B), a fan fairing 9b encircling a fan module counter-rotating units comprising a first fan S, a counter-rotating radial reduction unit 50, here called “PGB-CR”, and a second fan S'; a turbomachine 2 comprising a low pressure compressor 2a, a high pressure compressor 2b, a combustion chamber 2c, a high pressure turbine 2d, a low pressure turbine 2e and an exhaust nozzle 2f.
The high pressure compressor 2b and the high pressure turbine 2d are connected by a high pressure shaft 3. The low pressure compressor 2a and the low pressure turbine 2e are connected by a low pressure shaft 4.

The two fans S and S' are driven in counter-rotation respectively by fan shafts 6 and 60, connected to the low pressure shaft 4 of the turbomachine 2 by means of a radial reducer 5 with coaxial shafts according to patent WO2021245180A1 .
The axes of the high pressure shaft 3, the low pressure shaft 4 and the fan shafts 6 and 60 are substantially coincident with the axis of rotation X of the turbofan 10.

The PGB-CR 50 is positioned in the front part of the turbofan10. A module support 80, incorporated in the PGB-CR 50, is attached to a casing 8 comparable to an element of the stator of the turbofan 10. Said casing 8 is attached via a plurality of profiled radii 9, to the fairing of the blower 9b corresponding to a fixed frame of the turboblower 10.

As shown in Figures 4 and 5,
Said PGB-CR 50 is composed of 6 distinct subassemblies, from upstream to downstream, an upstream fan bearing support 7, subassemblies SE2, SE1 and SE2', a downstream fan bearing support 70, and a support module 80.
Said subassembly SE1, SE2 and SE2' together form said radial gearbox 5.
Said upstream fan bearing support 7 and downstream fan bearing support 70 integrate or incorporate between them, said subassemblies SE1, SE2 and SE2' of the radial reducer 5, so as to substantially encompass said radial reducer 5.

As shown in Figures 2, 3 and 4,
Downstream of the radial reducer 5, the shaft 4b of the subassembly SE1, of the radial reducer 5, is connected to a flexible sleeve 4a, for example via splines 4b1. Thus, the low pressure shaft 4, coupled to the flexible sleeve 4a, rotates and transmits the driving power of the turbomachine 2 to the shaft 4b of the radial reducer 5, rotatably mounted on a bearing support 4c via, by example, a 4c1 spherical bearing, or even in another embodiment not illustrated, a pair of ball bearings.
The shaft 4b rotates around the axis of screws to the sun wheel 21.

The sun wheel 21, preferably located in the present example, but not limited to, on the upstream side of the radial gearbox 5, is meshed and cooperates with a plurality of toothed pinions 22b; 22b', here called "internal satellite", for example, ten internal satellites 22b; 22b', each having their respective axis of rotation Y equally distributed around the axis of rotation X of the turbofan, transversely thereto.

In the present example, but not limited to, said axes of rotation Y are perpendicular to the axis of rotation X of the turbofan.
Said internal satellite 22b; 22b' further forming an integral part of pairs of toothed pinions 22 here called "satellite". Each of said satellite 22 being composed of an internal satellite 22b or 22b' and a flexible coupling 22c, coupling in rotation a second toothed pinion 22a here called "external satellite".

In the present example, but not limited to, said pinions and toothed wheels are conical pairs with spiral teeth.
Said sun wheel 21 driven by the shaft 4b, rotates said internal satellite 22b; 22b' which rotates said external satellite 22a via said coupling 22c.

The plurality of satellites 22 are held in their respective positions by a planet carrier 20 composed of a central hub 20a, on which as many pins 20b are attached as there are satellites 22, i.e., in this example, ten pins 20b. Each of said pins 20b is arranged so that each of said satellites 22 pivots substantially coaxially around a pin 20b. The axes of revolution of said journals 20b are therefore coincident with the axes of rotation Y of the satellites 22.

On an end proximal to the axis satellite 22.

Said outer annular strapping further comprising two circular plane faces 201 and 202 extending radially, coaxial with the axis of said plurality of satellites 22;
Two cylindrical walls 204 and 203, coaxial with the axis
Said outer annular strapping further comprising holes for screw passages, passing right through said circular flat faces 201 and 202.

On the , we can see the subassembly SE2 and the subassembly SE2', substantially symmetrical with respect to said median plane previously described, and therefore with respect to the axes of rotation Y of the plurality of toothed pinions 22a.
Said subassembly SE2 is generally composed of a second toothed wheel 30, here called "crown", attached to the fan shaft 6.
Said subassembly SE2' is generally composed of a third toothed wheel 300, here called "crown CR", attached to the fan shaft 60.

Referring to Figures 4 and 5, in order to incorporate said radial reducer 5 between said upstream fan bearing support 7 and downstream fan bearing support 70, said sub-assembly SE2 and SE2' of the radial reducer 5 are respectively mounted rotary on the pair of bearings 7a and 7b, and on the pair of bearings 70a and 70b.
Said bearings are preferably, for the intended application, but not limited to, of the conical roller type arranged head to tail. Other bearing arrangements not illustrated but well known to those skilled in the art could be used such as, for example, a pair of ball bearings or even a ball bearing associated with a roller bearing.

Furthermore, with the aim of connecting together the fixed parts of said PGB-CR 50, namely said upstream fan bearing support 7 and downstream fan bearing support 70, with said planet carrier 20 of the subassembly SE1;
The upstream fan bearing support 7 comprises, among other things, a cylindrical wall 73, of axis of revolution screw, and orthogonal to said cylindrical wall 73, so that when said circular flat face 72 and 202 are coplanar with each other, and said cylindrical wall 73 and 203 are coaxial with each other, the plurality of said toothed pinion 22a of the satellites 22 of the subassembly SE1 mesh and cooperate with said crown 30 of subassembly SE2, the axes of rotation of shaft 4b and fan shaft 6 of subassembly SE2 being substantially coincident.

The two sub-assembly SE1 and SE2 meshed and cooperating together operationally thus form a first upstream part of the radial reducer 5 integrated or incorporated into the upstream fan bearing support 7.

The downstream fan bearing support 70 comprises, among other things, a cylindrical wall 703, of axis of revolution screw, and orthogonal to said cylindrical wall 703, so that when said circular flat face 702 and 201 are coplanar with each other, and said cylindrical wall 703 and 204 are coaxial with each other, the plurality of said toothed pinion 22a of the satellites 22 of the subassembly SE1 mesh and cooperate with said crown CR 300 of subassembly SE2', the axes of rotation of shaft 4b and fan shaft 60 of subassembly SE2' being substantially coincident.

The two sub-assembly SE1 and SE2' meshed and cooperating together operationally thus form a second downstream part of the radial reducer 5 integrated or incorporated into the downstream fan bearing support 70.

A plurality of screws 41, only part of which is shown for purposes of clarity, passing through, through said holes in the screw passages, the annular wall 72 of the upstream fan bearing support 7, said outer annular ring of the planet carrier 20 of the subassembly SE1, and the annular wall 702 of the downstream fan bearing support 70, connects said fixed parts of the PGB-CR 50 together.

Furthermore, with the aim of attaching said fixed parts of the PGB-CR 50 to the stator of the turbofan 10, a module support 80, of axis of revolution X, generally composed of a cylindrical wall 80b and a conical wall 80a flaring radially from said cylindrical wall 80b towards said casing 8, is attached to the casing 8, for example, by a plurality of screws 82, and is attached in the upstream part, to the central hub 20a of the planet carrier 20, for example, by a plurality of screws 81 and grooves 20a1 and 80b1 cooperating with each other.

In the downstream part of said PGB-CR 50, the downstream fan bearing support 70 incorporates a bearing 70c, in order to allow a recovery of the forces between the downstream fan bearing support 70 and the module support 80, passing through the shaft of blower 60 mounted rotary.
Said bearing 70c is preferably for the intended application, but not limited to, a single ball type bearing. Other bearing arrangements not illustrated but well known to those skilled in the art could be used, such as, for example, a pair of ball bearings, a ball bearing associated with a roller bearing, or even two conical bearings mounted on the head. spade.

Therefore, when the sun wheel 21 of the radial gearbox 5 is rotated by the turbomachine 2, it rotates the plurality of satellites 22, consisting among others of said toothed pinions 22a, each rotating around their respective journals 20b, d axis Y, said pins 20b being held in their position by said planet carrier 20, fixed relative to the stator of the turbofan 10.
Said toothed pinion 22a, meshed and cooperating on an upstream side with the crown 30 and meshed and cooperating simultaneously on a downstream side with the crown CR 300, simultaneously cause the crown to rotate around the axis 30 and the crown CR 300, one in a direction of rotation opposite to the other.

Reduction ratios existing between the different gears 21;22b;22b';22a;30 or 300, of the radial reducer 5, cause the crown 30 and the crown CR 300 to rotate at a rotation speed slower than the speed of rotation of shaft 4b.

Depending on the more or less transverse orientation angle of the axes of rotation Y of the satellites 22, relative to the axis or different. In the case of the present example where the axes of rotation Y are substantially perpendicular to the axis of rotation X of the turbofan, the speed of rotation of the crown 30 and the crown CR 300 are substantially identical.
Said crown 30 and crown CR 300 being coupled respectively to the blowers S and S', the latter are driven simultaneously in contra-rotation relative to each other, at a rotation speed slower than the rotation speed of the turbomachine 2.

Numerous advantages are provided by such an aircraft engine incorporating a counter-rotating fan module reduced according to the present invention, in particular a significant gain in propulsive efficiency, compactness as well as increased reliability of the contra-rotating reduction gear, provided by the fact that numerous forces oppose and cancel each other, thus limiting the loads on the internal components of said contra-rotating gearbox.

Claims (12)

Counter-rotating fan module for X-axis turbofan 10 composed from upstream to downstream, of said counter-rotating fan module and a gas turbomachine 2;
Said contra-rotating fan module comprising, from upstream to downstream, a first fan S, a counter-rotating radial reduction unit 50, and a second fan S';
Said counter-rotating radial reduction unit 50 comprising, among other things, a module support 80 and a radial speed reducer 5, with coaxial shafts of axis X, with gears with concurrent axes, formed of three subassemblies SE1; SE2; SE2';
Said subassembly SE2, being generally composed of a ring 30 rotatably mounted around X, coaxial and integral with a fan shaft 6 connected to said fan S;
Said subassembly SE2', being generally composed of a crown CR 300 rotatably mounted around X, coaxial and integral with a fan shaft 60 connected to said fan S'; And
Said subassembly SE1, comprising, among other things, a plurality of satellites 22, equally distributed around X, with axis of rotation Y transverse to
characterized in that said blowers S and S' are arranged or positioned on either side of said radial reducer 5, respectively upstream and downstream of said radial reducer 5, said module support 80, of axis of revolution X, attaching said central hub 20a of the radial gearbox 5 to a casing 8 comparable to an element of the stator of the gas turbomachine 2 of the turbofan 10. Blower module according to claim 1, characterized in that said planet carrier 20 is composed of a central hub 20a, of axis X, on which are attached a plurality of pins 20b, of axis Y transverse to extending radially in order to be attached, on their end distal to Blower module according to the preceding claims, characterized in that said module support 80, of axis of revolution towards a casing 8 comparable to an element of the stator of the gas turbomachine 2 of the turbofan 10, to be attached to said casing 8, for example, by a plurality of screws 82. Blower module according to the preceding claims, characterized in that said module support 80 is attached, in the upstream part, to said central hub 20a of the planet carrier 20, by grooves 20a1; 80b1 and/or a plurality of screws 81 , making said planet carrier 20 fixed relative to the stator of said gas turbomachine 2. Blower module according to the preceding claims, characterized in that a low pressure shaft 4 rotates and transmits the driving power of said turbomachine 2, via a flexible sleeve 4a, to a shaft 4b rotatably mounted on , integral with a solar wheel 21. Blower module according to the preceding claims, characterized in that said satellites 22, composed of a pair of conical toothed pinions 22b; 22b' and 22a, connected in rotation by a flexible coupling 22c, rotate simultaneously in rotation, each around their respective pin 20b, when said sun wheel 21, cooperating in mesh engagement with said toothed pinion 22b; 22b', is rotated by the turbomachine 2. Blower module according to the preceding claims, characterized in that an upstream fan bearing support 7 incorporates said sub-assembly SE2 rotatably mounted on , to form a first upstream part of said radial reducer 5 incorporated in the counter-rotating radial reducer group 50. Blower module according to the preceding claims, characterized in that a downstream fan bearing support 70 incorporates said subassembly SE2' rotatably mounted on X, so that said crown CR 300 cooperates in mesh engagement with said plurality of pinions toothed 22a, to form a second downstream part of said radial reducer 5 incorporated in the counter-rotating radial reducer group 50. Blower module according to the preceding claims, characterized in that said upstream fan bearing support 7 and downstream fan bearing support 70, are attached to said outer annular ring of the planet carrier 20, for example, by a plurality of screws 41, in order to to include said radial reducer 5 and connect together the fixed parts of said counter-rotating radial reducer group 50. Blower module according to the preceding claims, characterized in that said downstream fan bearing support 70 incorporates, at least, one bearing 70c, in order to allow a recovery of the forces between the downstream fan bearing support 70 and said module support 80, in passing through the rotatably mounted fan shaft 60. Blower module according to the preceding claims, characterized in that the fan S connected to the crown 30 and the fan S' connected to the crown CR 300, rotate counter-rotating to each other, at a rotation speed slower than the rotation speed of said shaft 4b. Blower module according to the preceding claims, characterized in that, as a variant or in combination, said blowers S;S' rotate in contra-rotation to each other, at an identical rotation speed in the case where the axes Y of said satellites 22 are perpendicular to the axis X, and rotate at a different rotation speed in other cases.