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: Running gear for a vehicle, comprising a wheel and a device for driving the wheel in rotation, aircraft landing gear and aircraft comprising such running gear

[0001] The present invention relates to the movement on the ground 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 driving the wheel in rotation 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 devices for rotating the wheels to enable the aircraft to be moved on the ground without using its powertrains.

[0004] An aircraft wheel generally comprises a rim connected by a web to a hub which is mounted for rotation 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 aircraft (eVTOL), it has been considered to mount such devices next to the wheels.

[0006] However, the landing gear of eADAVs is generally fixed, i.e. not movable between a retracted position 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 therefore the energy consumption of the eADAV in flight.

[0007] However, climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft and those currently in circulation requiring the implementation of technological solutions in order to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0008] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. All stakeholders in the sector are constantly working to improve energy efficiency. The Applicant takes into consideration the impacting factors in 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 and minimizing greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

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

[0011] SUBJECT OF THE INVENTION

[0012] The invention results from this work and aims to propose a running gear for a vehicle making it possible to at least partially overcome the aforementioned drawbacks. Summary of the invention

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

[0014] The integration of the electric motor in the reducer makes it possible to limit the overall volume of the drive device and therefore to limit the drag forces which oppose the movement of the running gear.

[0015] According to a particular characteristic, the reducer comprises a deformable crown having a first toothing and an external crown having a second toothing which meshes with the first toothing and which has a number of teeth different from that of the first toothing, the motor rotating at least one radial deformation element of the deformable crown.

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

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

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

[0019] According to another particular characteristic, 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 mounted fixedly on an external periphery of the axle, and the rotor is mounted rotatably on the external periphery of the axle.

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

[0022] The invention also relates to an aircraft landing gear comprising an end comprising 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 light of the following description, which is purely illustrative and non-limiting, and must be read in conjunction with the appended drawings, among which:

[0025] [Fig-1] [Fig.l] is a simplified representation of an aircraft comprising landings- main risers each equipped with a motorized wheel;

[0026] [Fig.2A] [Fig.2A] is an axial sectional view of one of the powered 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 of the motorized wheel illustrated 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 landing gears 2, each comprising a leg 3 which has an upper end fixed to a structure 4 of the aircraft and, opposite, a lower end carrying a wheel 10 rotating about an axis X on a tubular shaft or axle 5 (visible in FIGS. 2A and 2B). The landing gears 2 are fixed here, but the invention is applicable to retractable type landing gears, 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 which each comprise an annular rim 11a, 11b connected by a web 12a, 12b to a half-hub 13a, 13b pivotally received on the axle 5 by means of a bearing 14a, 14b. The half-hubs 13a, 13b each comprise a distal end comprising a bore in which the bearings 14a, 14b are received.

[0030] The half-wheel 10a comprises a housing (not shown) provided on an edge of the rim 11a 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 axis X of rotation of the wheel 10 and comprise 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 holes drilled opposite each other 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 11a, 11b. In this position, the sealing gasket is elastically compressed between the half-wheels 10a, 10b.

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

[0034] The axle 5 comprises: • a first section 5a, of cylindrical shape, extending inside the half-hubs 13a, 13b and on which the bearings 14a, 14b are mounted to carry the wheel 10; • a second section 5b, of cylindrical shape, extending in projection from the wheel 10, in the extension of the first section 5a, and delimiting 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 cone shape, extending in the extension 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 axis X of rotation of the wheel 10.

[0036] The bearing 14a comprises 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 rotational drive device 100 intended to move the aircraft 1 without using its powertrains when the latter is on the ground.

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

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

[0040] The stator 111 here has the form of a crown mounted fixedly 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 keep the stator 111 pressing 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 axis X and on which windings 111b are wound.

[0042] The rotor 112 is mounted to rotate about the axis X on the third section 5c of the axle 5 by means of a bearing 115 against which the spacer 113 bears, and comprises an annular portion 112a, of cylindrical shape, inside which the stator 111 extends. The annular portion 112a extends around the stator 111 and comprises an internal periphery provided with a series of magnets 112b capable of interacting 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 to rotate about the X axis, a deformable ring gear 122 mounted on the wave generator 121 by means of a so-called deformable bearing 123, and an outer ring gear 124 meshing with the deformable ring gear 122.

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

[0045] The deformable crown 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 external crown 124, and a second end, opposite the first end, which is connected by a web to a hub pivotally received on the second section 5b of the axle 5 by means of bearings 125. The external toothing of the deformable crown 122 has a number of teeth different from that of the internal toothing of the external crown 124. The hub of the deformable crown 122 is provided with a front toothing meshing with a front toothing of the half-hub 13a of the wheel 10 so that said wheel 10 is linked in rotation to said deformable crown 122.

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

[0047] The deformable crown 122 and the outer crown 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 crown 122 and said outer crown 124 provide 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 crown 122 respectively form an input shaft and an output shaft of the reducer 120.

[0049] It will be noted that by associating several functions within the reducer 120 with the same part, the drive device 100 is particularly compact and lightweight.

[0050] [Fig.2B] illustrates a drive device 100' which is none other than a variant of the drive device 100 illustrated in [Fig.2A]. The drive device 100' comprises the radial flux electric motor 110 and a single-stage deformation wave reducer 120' making it possible to increase 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 crown 122 and the outer crown 124 are replaced by respectively a deformable crown 122' and an outer crown 124' meshing with the deformable crown 122'.

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

[0053] The deformable crown 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 external crown 124', and a second end, opposite 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 landing gear 2. The external toothing of the deformable crown 122' has a number of teeth different from that of the internal toothing of the external crown 124'.

[0054] The outer crown 124' is fixed to the distal end of the rim 11a 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 linked in rotation to the outer crown 124'.

[0055] The deformable crown 122' and the outer crown 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 crown 122' and said outer crown 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' respectively form an input shaft and an output shaft of the reducer 120'.

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

[0058] During the 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 will also be noted that the drive devices 100, 100': • are electrically powered independently of the aircraft's powertrains 1; • can be easily added or removed from the axle 5, which simplifies assembly and maintenance operations of the landing gear 2; • allow the wheel 10 to rotate freely when the electric motor 110 is not in operation, or even broken down; • allow aircraft 1 to be moved on the ground without using its power units; and • allow wheel 10 to be rotated before aircraft 1 touches the ground in order to minimize tire wear when 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 structure different 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 bead is interposed to secure these two parts together, be made in a single piece, made in a foundry or by additive manufacturing, etc.

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

[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 may be of the "pancake" type, i.e. wide and flat and having rapid acceleration and deceleration using a high number of pole pairs.

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

[0067] Although the deformation element 121a here comprises an external surface of elliptical section, it can be of another nature: diametrically opposed rollers...

[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 11a, the disc 12a and the half-hub 13a.

[0069] The invention can be used on any type of vehicle, air, land or amphibious, or any mobile industrial or transport equipment requiring braking.

Claims

Claims

1. Running gear for a vehicle (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 a motor (110) coaxially mounted on the axle, and a strain wave reducer (120, 120') inside which the motor extends.

2. Running gear according to claim 1, in which the reducer (120, 120') comprises a deformable crown (122, 122') having a first toothing and an outer crown (124, 124') having a second toothing which meshes with the first toothing and which has a number of teeth different from that of the first toothing, the motor rotating at least one radial deformation element (121a) of the deformable crown.

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

4. Running gear according to claim 2 or 3, in which the deformable crown (122) is rotationally connected to the wheel (10) and the outer crown (124) is rotationally connected to the axle (5), the deformable crown forming an output of the reducer (120).

5. Running gear according to claim 2 or 3, in which the deformable crown (122') is rotationally connected to the axle (5) and the outer crown (124') is rotationally connected to the wheel (10), the outer crown forming an output of the reducer (120').

6. A running gear 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. Running gear according to claim 6, in which the stator (111) is fixedly mounted on an external periphery of the axle (5), and the rotor (112) is mounted to rotate on the external periphery of the axle.

8. Running gear according to claim 6 or 7, in which the reducer (120, 120') comprises a radial deformation element (121a) of a deformable crown (122, 122') meshing with an outer crown (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. Landing gear (2) of an aircraft (1), comprising one end comprising 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.

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