Vehicle undercarriage, comprising a wheel and a wheel rotation drive device, aircraft landing gear, and aircraft comprising such undercarriage

Abstract

Vehicle undercarriage (1) comprising an axle (5), a wheel (10) rotatably mounted on the axle (5), and a drive device (100, 100') for rotating the wheel relative to the axle, the drive device comprising an electric motor (110) mounted on the axle, and a strain-wave reduction gear (120, 120') within which the electric motor extends. Aircraft landing gear (2) and aircraft (1) comprising such undercarriage. FIGURE IN ABBREVIATION: Fig. 2A

Description

Title of the invention: Vehicle undercarriage, comprising a wheel and a wheel rotation drive device, aircraft landing gear, and aircraft comprising such undercarriage

[0001] The present invention relates to the ground movement of a vehicle, and more particularly to running gear comprising a shaft or axle, a wheel pivotally mounted on the shaft, and a device for rotating the wheel relative to the shaft. The invention also relates to an aircraft landing gear and an aircraft comprising such running gear.

[0002] BACKGROUND OF THE INVENTION

[0003] In the field of aviation, it is now planned to equip aircraft with wheel rotation drive devices to allow the aircraft to move on the ground without using its powertrains.

[0004] An aircraft wheel generally comprises a rim connected by a disc to a hub which is mounted to rotate on a shaft or axle carried by a lower end of a landing gear.

[0005] In the case of electric vertical take-off and landing (eVTOL) aircraft, it has been envisaged to mount such devices next to the wheels.

[0006] However, the landing gear of eVTOLs is generally fixed, i.e., not mobile between a retracted and a deployed position as is the case for airliners. Increasing the size of the wheels to integrate drive devices would therefore tend to increase the drag forces exerted on the landing gear during flight, and thus the energy consumption of the eVTOL in flight.

[0007] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new types of aircraft and those currently in operation, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively working for several years now to contribute to the fight against climate change.

[0008] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. All stakeholders in the sector are constantly working to improve energy efficiency. The Applicant takes into account the factors impacting all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental impacts with the aim of improving the energy efficiency of air transport.

[0009] Consequently, the Applicant is constantly working to reduce its climate impact by using methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0010] This sustained research and development work focuses on new generations of aircraft engines, the lightening of aircraft, in particular through the materials used and lighter on-board equipment, the development of the use of electrical technologies to provide propulsion, and, as essential complements to technological progress, aviation biofuels.

[0011] SUBJECT OF THE INVENTION

[0012] The invention results from this work and aims to provide a vehicle running gear that allows at least partially to overcome the aforementioned disadvantages. Summary of the invention

[0013] For this purpose, a vehicle running gear is provided comprising an axle, a wheel mounted for rotation on the axle, and a device for driving the wheel for rotation relative to the axle, the drive device comprising a motor mounted coaxially on the axle, and a deformation wave reducer within which the motor extends.

[0014] Integrating the electric motor into the reducer makes it possible to limit the overall size of the drive device and therefore to limit the drag forces that oppose the movement of the running gear.

[0015] According to a particular feature, the reducer comprises a deformable ring having a first set of teeth and an outer ring having a second set of teeth which meshes with the first set of teeth and which has a number of teeth different from that of the first set of teeth, the motor driving in rotation at least one radial deformation element of the deformable ring.

[0016] In particular, the outer ring and the deformable ring are arranged to form a cover for at least part of the drive device.

[0017] In particular, the deformable ring is rotationally linked to the wheel and the outer ring is rotationally linked to the axle, the deformable ring forming an output of the reducer.

[0018] In particular, the deformable ring is rotationally linked to the axle and the outer ring is rotationally linked to the wheel, the outer ring forming a output of the reducer.

[0019] According to another particular feature, the motor is a radial flux electric motor and comprises a stator and a rotor extending around said stator.

[0020] In particular, the stator is fixedly mounted on an external circumference of the axle, and the rotor is mounted to rotate freely on the external circumference of the axle.

[0021] In particular, the reducer includes a radial deformation element of a deformable ring meshing with an outer ring, the radial deformation element being mounted on an outer periphery of the rotor and comprising an outer surface of elliptical cross-section.

[0022] The invention also relates to an aircraft landing gear comprising an end having such a running gear.

[0023] The invention further relates to an aircraft comprising at least one such landing gear. Brief description of the drawings

[0024] The invention will be better understood in the light of the following description, which is purely illustrative and not limiting, and should be read in conjunction with the accompanying drawings, among which:

[0025] [Fig-1] [Fig.1] is a simplified representation of an aircraft including landing gear main rollers each equipped with a motorized wheel;

[0026] [Fig. 2A] [Fig. 2A] is an axial cross-sectional view of one of the motorized wheels of the aircraft illustrated in [Fig. 1], according to a particular embodiment of the invention; and

[0027] [Fig. 2B] [Fig. 2B] is a view identical to [Fig. 2A], illustrating a variant of the drive device for the motorized wheel shown in [Fig. 2A]. DETAILED DESCRIPTION OF THE INVENTION

[0028] With reference to [Fig. 1], the invention is described in application to an electric vertical take-off and landing (eVOTL) aircraft 1. The aircraft 1 comprises two main landers 2, each having a leg 3 with an upper end fixed to a structure 4 of the aircraft and, at the opposite end, a lower end carrying a wheel 10 rotating about an axis X on a tubular shaft or axle 5 (visible in Figures 2A and 2B). The landers 2 are fixed here, but the invention is applicable to retractable landers, or even to another type of aircraft or vehicle such as a land vehicle.

[0029] With reference to [Fig. 2A], the wheel 10 comprises two half-wheels 10a, 10b, each of which has an annular rim 1la, 11b connected by a disc 12a, 12b to a half-hub 13a, 13b received by pivoting on the axle 5 by means of a bearing 14a, 14b. The half-hubs 13a, 13b each have a distal end comprising a bore in which the bearings 14a, 14b are received.

[0030] The half-wheel 10a has a housing (not shown) provided on an edge of the rim 1la and in which a sealing gasket is arranged so that it is elastically compressed between the half-wheels 10a, 10b once they are assembled.

[0031] The half-wheels 10a, 10b are brought together in a direction parallel to the X axis of rotation of the wheel 10 and have centering bearing surfaces (not shown) to ensure the correct relative positioning of the half-wheels 10a, 10b. The half-wheels 10a, 10b are held in position by assembly bolts (not shown) arranged in opposite holes drilled in the webs 12a, 12b.

[0032] In a manner known per se, the bolts are screwed and tightened to assemble the half-wheels 10a, 10b after mounting a tire (not shown) on the rims 1la, 11b. In this position, the sealing gasket is elastically compressed between the half-wheels 10a, 10b.

[0033] The half-wheels 10a, 10b each have an annular rim 15a, 15b arranged at a distal end of the rim 11a, 11b and extending radially outwards from the wheel 10. The rim rims 15a, 15b form radial stops preventing the tire from coming off the rim.

[0034] Axle 5 comprises: • a first section 5a, cylindrical in shape, extending inside the half-hubs 13a, 13b and on which the bearings 14a, 14b are mounted to support the wheel 10; • a second section 5b, cylindrical in shape, projecting from the wheel 10, in line with the first section 5a, and defining with said first section 5a a first shoulder 6.1, the second section 5b having a diameter greater than that of the first section 5a; and • a third section 5c, of truncated conical shape, extending in the continuation of the second section 5b and delimiting with the latter a second shoulder 6.2, the third section 5c having a diameter greater than that of the second section 5b.

[0035] The first, second and third sections 5a, 5b, 5c extend coaxially to the X axis of rotation of the wheel 10.

[0036] The bearing 14a includes an inner ring bearing against the first shoulder 6.1 of the axle 5 and a free end of the first section 5a receives a retaining nut 7 bearing against an inner ring of the bearing 14.b, so that the wheel 10 is immobile in translation along the axis X with respect to the axle 5.

[0037] The wheel 10 is said to be "motorized", that is to say, equipped with a rotating drive device 100 intended to move the aircraft 1 without using its power-driven propulsion units when it is on the ground.

[0038] The drive device 100 comprises a radial flux electric motor 110 and a single-stage 120 reducer allowing the drive torque delivered to wheel 10 by electric motor 110 to be increased.

[0039] In a manner known per se, the electric motor 110 comprises a fixed element or stator 111, and a rotating moving element or rotor 112. The stator 111 and the rotor 112 each have a central axis coinciding with the X axis of rotation of the wheel 10, the stator 111 extending inside the rotor 112.

[0040] The stator 111 here has the form of a ring mounted fixed on an external periphery of the third section 5c of the axle 5, between a spacer 113 and a retaining nut 114 received at one end of the third section 5c to hold the stator 111 in support against the spacer 113, so that said stator 111 is immobile with respect to the axle 5.

[0041] The stator 111 comprises a pack of laminations 111a forming a plurality of teeth which extend radially around the X axis and on which windings 111b are wound.

[0042] The rotor 112 is mounted to rotate freely about the axis X on the third section 5c of the axle 5 by means of a bearing 115 against which the spacer 113 rests, and comprises an annular portion 112a, cylindrical in shape, inside of which the stator 111 extends. The annular portion 112a extends around the stator 111 and comprises an inner circumference provided with a series of magnets 112b adapted to interact with the windings 111b carried by said stator 111 to drive the rotor 112 in rotation.

[0043] The reducer 120 is a deformation wave reducer. It comprises a wave generator 121 mounted movable in rotation about the X axis, a deformable ring 122 mounted on the wave generator 121 by means of a bearing 123 called deformable, and an outer ring 124 meshing with the deformable ring 122.

[0044] The wave generator 121 includes a radial deformation element 121a of the deformable ring 122. The deformation element 121a is fixedly mounted on an external periphery of the annular portion 112a of the rotor 112, and here includes an external surface of elliptical cross-section whose vertices are in contact with an internal bearing surface of the bearing 123.

[0045] The deformable ring 122 comprises a tubular portion having a first end provided with a first external toothed section meshing with a second internal toothed section of the outer ring 124, and a second end, opposite the first end, which is connected by a flange to a hub pivotally mounted on the second section 5b of the axle 5 by means of bearings 125. The external toothed section of the deformable ring 122 has a different number of teeth than the internal toothed section of the outer ring 124. The hub of the deformable ring 122 is provided with a front toothed section meshing with a front toothed section of the half-hub 13a of the wheel 10 so that said wheel 10 is rotationally connected to said deformable crown 122.

[0046] The outer ring 124 is arranged so as to be fixed relative to the axle 5, by being connected for example directly or indirectly to the axle 5, or even to the leg 3 of the lander 2.

[0047] The deformable ring 122 and the outer ring 124 extend radially around the electric motor 110 and protect said electric motor 110 from external aggressions by forming a protective casing, so that said deformable ring 122 and said outer ring 124 perform a dual function: they are part of the force transmission chain of the drive device 100 and they protect said drive device 100.

[0048] The rotor 112 and the deformable ring 122 form respectively an input shaft and an output shaft of the reducer 120.

[0049] It should be noted that by combining several functions within the reducer 120 into a single part, the drive device 100 is particularly compact and lightweight.

[0050] Figure 2B illustrates a drive device 100' which is a variant of the drive device 100 shown in Figure 2A. The drive device 100' comprises the radial flux electric motor 110 and a single-stage strain-wave reducer 120' which increases the drive torque delivered to the wheel 10 by the electric motor 110.

[0051] The reducer 120' differs from the reducer 120 in that the deformable ring 122 and the outer ring 124 are replaced respectively by a deformable ring 122' and an outer ring 124' meshing with the deformable ring 122'.

[0052] The reducer 120' comprises the wave generator 121 mounted movable in rotation about the X axis, the deformable ring 122' mounted on the wave generator 121 by means of the bearing 123, and the outer ring 124'.

[0053] The deformable ring 122' comprises a tubular portion having a first end which is provided with a first external toothing meshing with a second internal toothing of the outer ring 124', and a second end, opposite to the first end, which is connected to a web arranged so as to be fixed relative to the axle 5. For example, the web is connected directly or indirectly to the axle 5, or even to the leg 3 of the lander 2. The external toothing of the deformable ring 122' has a different number of teeth than the internal toothing of the outer ring 124'.

[0054] The outer ring 124' is fixed to the distal end of the rim lia by means of screws 16 which extend parallel to the axis X and which are distributed equally around said axis X, so that the wheel 10 is rotationally linked to the outer ring 124'.

[0055] The deformable ring 122' and the outer ring 124' extend around the electric motor 110 and protect said electric motor 110 from external aggressions by forming a protective casing, so that said deformable ring 122' and said outer ring 124' perform a dual function: they are part of the force transmission chain of the drive device 100' and they protect said drive device 100'.

[0056] The rotor 112 and the outer ring 124' form respectively an input shaft and an output shaft of the reducer 120'.

[0057] As with the drive device 100, it should be noted that by combining several functions within the reducer 120' in the same part, the drive device 100' is particularly compact and lightweight.

[0058] During deceleration phases, the electric motor 110 can be used as a generator to produce electrical energy and, for example, recharge batteries powering said electric motor 110.

[0059] It should also be noted that the training devices 100, 100': • are electrically powered independently of the aircraft's propulsion units 1; • can be easily added to or removed from axle 5, which simplifies the assembly and maintenance operations of lander 2; • allow the wheel 10 to rotate freely when the electric motor 110 is not in operation, or even broken down; • allow the aircraft 1 to move on the ground without using its propulsion systems; and • allow the wheel 10 to rotate before the aircraft 1 touches the ground in order to minimize tire wear when the aircraft 1 moves forward during landing.

[0060] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0061] The wheel 10 may have a different structure from that described. The rim 11 of the wheel 10 may, for example, be formed of a main part and an auxiliary part between which a flange is interposed to join these two parts together, be made in a single piece, produced by casting or by additive manufacturing...

[0062] Although the motor 110 is electric here, it can be of another type (hydraulic, pneumatic, thermal...).

[0063] Although here the electric motor 110 is radial flux, it can also be axial flux.

[0064] Although here the stator 111 of the electric motor 110 extends inside the rotor 112, the rotor 112 can, conversely, extend inside the stator 111.

[0065] The electric motor 110 can be of the "pancake" type, i.e. wide and flat and exhibiting rapid acceleration and deceleration by means of a high number of pole pairs.

[0066] The magnets 112b can be carried by the stator 111 instead of the rotor 112.

[0067] Although the deformation element 121a here comprises an outer surface with an elliptical cross-section, it can be of another nature: diametrically opposed pebbles...

[0068] Although here the drive device 100, 100' extends here outside the wheel 10, it can also extend, at least in part, inside said wheel 10, in other words in the annular space delimited by the rim 1a, the disc 12a and the half-hub 13a.

[0069] The invention is usable on any type of vehicle, aerial or terrestrial or amphibious, or any industrial or transport mobile equipment requiring braking.

Claims

Demands

1. Vehicle running gear (1) comprising an axle (5), a wheel (10) mounted for rotation on the axle (5), and a drive device (100, 100') for rotation of the wheel relative to the axle, the drive device comprising a motor (110) mounted coaxially on the axle, and a deformation wave reducer (120, 120') within which the motor extends.

2. Rolling stock according to claim 1, in which the reducer (120, 120') comprises a deformable ring (122, 122') having a first set of teeth and an outer ring (124, 124') having a second set of teeth which meshes with the first set of teeth and which has a different number of teeth than the first set of teeth, the motor driving in rotation at least one radial deformation element (121a) of the deformable ring.

3. Undercarriage according to claim 2, wherein the deformable ring (122, 122') and the outer ring (124, 124') are arranged to form a hood of at least a part of the drive device (100, 100').

4. Rolling stock according to claim 2 or 3, wherein the deformable ring (122) is rotationally linked to the wheel (10) and the outer ring (124) is rotationally linked to the axle (5), the deformable ring forming an output of the reducer (120).

5. Rolling stock according to claim 2 or 3, wherein the deformable ring (122') is rotationally linked to the axle (5) and the outer ring (124') is rotationally linked to the wheel (10), the outer ring forming an output of the reducer (120').

6. Rolling stock according to claim 1, wherein the motor (110) is a radial flux electric motor and comprises a stator (111) and a rotor (112) extending around said stator.

7. Rolling stock according to claim 6, wherein the stator (111) is fixedly mounted on an outer perimeter of the axle (5), and the rotor (112) is movablely rotated on the outer perimeter of the axle.

8. Undercarriage according to claim 6 or 7, wherein the gearbox (120, 120') comprises a radial deformation element (121a) of a deformable ring (122, 122') meshing with an outer ring (124, 124'), the radial deformation element being mounted on an outer periphery of the rotor (112) and comprising an outer surface of

9. elliptical section. Aircraft landing gear (2) of aircraft (1), comprising an end having a running gear according to any one of the preceding claims.

10. Aircraft (1) comprising at least one landing gear (2) according to claim 9.

Images