ROD FOR BRAKED AIRCRAFT WHEEL

Description

[0001] The present invention relates to the field of aeronautics and, more particularly, to the braking of aircraft wheels. BACKGROUND OF THE INVENTION

[0002] Aircraft wheels mounted on landing gear and equipped with a brake are known. The brake generally comprises stator discs arranged alternately with rotor discs driven by Inconel alloy bars attached to the lower edge of a wheel rim. The bars are received in peripheral slots on the rotor discs in a direction substantially parallel to an axis of rotation of the wheel. Controlled pressure applied to all the discs generates friction between the opposing discs, thus producing a braking torque that slows the wheel's rotation.

[0003] The spokes can be made from the same material as the wheel rim or attached to it. In reference to the figure 1A Some known spacers 1 have at one end 1a a cylindrical shank designed to fit into holes in a rim face, and at the opposite end 1b a hole designed to receive a screw that threads into a tapped hole in the rim. Titanium spacers 2 are interposed between the spacers 1 and the rim to, firstly, position the spacers 1 parallel to the wheel's axis of rotation and, secondly, help limit heat flow between the discs and the rim, which can be detrimental to a tire mounted on the rim.

[0004] As illustrated in the figure 1B The bars 1 sometimes have a generally constant H-shaped cross-section. Such a section allows them to withstand the mechanical stresses induced by braking and in particular the shear and bending stresses generated by the slowing down of the rotor discs.

[0005] Such bars are known, for example, from document FR-A-2937949. Other bars with an H shape are known from documents EP-A1-2940340 and US-A-6003954.

[0006] An aircraft braked wheel can have seven to eleven bars 1 depending on the wheel size. Since an aircraft has two to six wheels per landing gear and a bar 1 weighs 500 to 800 grams, it appears that the bars contribute significantly to the overall mass of the wheel-brake assembly.

[0007] However, aircraft weight reduction has become an essential objective for all aircraft manufacturers, especially since regulations are pushing them in this direction. Environmental standards require the reduction of pollutant emissions, particularly carbon dioxide (CO2). SUBJECT OF THE INVENTION

[0008] The invention therefore aims to provide a brake bar for aircraft wheels which allows in particular to reduce the mass of the wheel-brake assembly of an aircraft without degrading the mechanical resistance of said bar. SUMMARY OF THE INVENTION

[0009] To this end, the invention proposes a brake bar for an aircraft wheel, designed to be mounted on a wheel rim to drive rotor brake discs into rotation. The bar comprises a substantially straight body, at least one section of which has two wings connected by a web and designed to cooperate with the rotor discs.

[0010] According to the invention, the bar comprises two bracing elements connecting an upper part of each of the wings to a central part of the web.

[0011] Such bracing elements allow for optimal adjustment of the thicknesses of the wings and the web, and therefore reduce the overall mass of the bar without altering its mechanical resistance.

[0012] According to a particular embodiment, the bracing element is a wall extending along a longitudinal direction of the barrette between said free edge and the central part of the web.

[0013] According to a particular characteristic, a portion of the body forms a wedge for fixing the bar to the rim.

[0014] Therefore, it is no longer necessary to plan for an operation to add a shim when mounting the bar, which limits the number of operations required to mount the bar on the wheel rim.

[0015] Advantageously, the spacer has recesses, which helps to limit the overall mass of the bar but also to limit heat transfer to the rim.

[0016] According to another particular characteristic, a portion of the body has a lattice structure.

[0017] The invention also relates to an aircraft braked wheel comprising a rim having an inner perimeter defining a space for receiving brake rotor discs, and such bars fixed to the rim to link the brake rotor discs to the rim in rotation.

[0018] The invention further relates to a landing gear comprising at least one such wheel and an aircraft comprising such a landing gear.

[0019] The invention also relates to a method for manufacturing such a bar, said method comprising at least one additive manufacturing operation of the body of the bar.

[0020] According to a particular implementation method, the additive manufacturing operation is carried out in such a way as to obtain the bar in a vertical position.

[0021] Alternatively, the additive manufacturing operation is carried out in such a way as to obtain the bar in a horizontal position and includes the step of creating a lattice supporting a wall of the bar body.

[0022] Preferably, the additive manufacturing operation uses laser powder bed fusion.

[0023] In particular, the powder is an Inconel brand alloy powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will be better understood in light of the following description, which is purely illustrative and not limiting, and should be read in conjunction with the accompanying drawings, among which: there figure 1A is a perspective view of a barrette from the prior art; [ Fig. 1B ] there figure 1B is a cross-sectional view along plane AA of the barrette illustrated in the figure 1A ; there figure 2 is a side view of an aircraft including landing gear equipped with braked wheels; the figure 3 is an axial cross-sectional view of one of the braked wheels of the aircraft illustrated in the figure 2 , the rim of which is equipped with bars according to a particular embodiment of the invention; the figure 4A is a perspective view of a bar of the braked wheel illustrated in the figure 3 ; there figure 4B is a cross-sectional view along plane A'-A' of the barrette illustrated in the figure 4A ; there figure 4C is a detailed front view of a portion of the bar illustrated in the figure 4A ; there figure 4D is a detailed rear view of a portion of the barrette illustrated in the figure 4A ; there figure 5 is a cross-sectional view of a variant of the barrette illustrated in the figure 4A including a portion comprising a lattice structure. DETAILED DESCRIPTION OF THE INVENTION

[0025] With reference to figures 2 et 3 An aircraft 100 according to the invention comprises a structure provided with landing gear 101. Each landing gear 101 comprises a leg having one end articulated to the structure of the aircraft 100 and an opposite end carrying an axle 102 on which a wheel 103 is mounted to pivot.

[0026] The wheel 103 comprises a rim 104 and a disc 105 connecting the rim 104 to a hub received for pivoting on the axle 102 such that an inner surface of the rim 104 extends opposite an outer surface of the hub and, together with the latter, defines a space for receiving a stack of brake discs. The stack comprises stator discs 106a fixed for rotation relative to the landing gear leg and rotor discs 106b having peripheral notches for receiving bars, generally designated as 10, fixed to the inner surface of the rim 104.

[0027] With reference to the figure 4A Each bar 10 comprises a body 11 extending along a longitudinal axis X. The body 11 comprises a first end 11a in the form of a cylindrical tail intended to be received in an orifice of the rim 104 extending parallel to an axis of rotation of the wheel 103, and a second end 11b having a drilling 12 in a radial direction intended to receive a screw for fixing the bar 10 to the rim 104.

[0028] The body 11 also includes two lateral bearing surfaces 13 extending parallel to the X-axis and designed to cooperate with riders arranged in the peripheral notches of the brake rotor discs 106b. The two bearing surfaces 13 form a non-zero angle α so that, in operation, they extend radially with respect to the rim 104. A High Velocity Oxy Fuel (HVOF) surface treatment is applied to the bearing surfaces 13 to achieve suitable tribological behavior between the bar 10 and the riders. All of this is well known and is mentioned only for informational purposes.

[0029] Between the first end and the second end, the body 11 comprises a section 14 having, as illustrated in the figure 4B , a cross-section that is generally constant and symmetrical with respect to a median plane of the body 11. The cross-section is substantially H-shaped, and the section 14 thus comprises two wings 15 which have inner faces connected by a web 16 and outer faces forming the bearing surfaces 13. The wings 15 comprise a lower part 15a and an upper part 15b, each extending on either side of the web 16. The upper parts 15b of the wings 15 are here taller than the lower parts 15a. The height of the upper parts 15b of the wings 15 is here substantially equal to four times that of the lower parts 15a of the wings 15. The distance separating the free edges of the upper parts 15b of the wings 15 is slightly greater than that separating the free edges of the lower parts 15a of the wings 15.

[0030] Furthermore, bracing elements 17 connect the free edges of the upper portions 15b of the flanges 15 to a central portion of the web 16. Each bracing element 17 comprises a wall having a flat area 17a extending between the central portion of the web 16 and a rounded area 17b that connects the flat area 17a to the free edge of the upper portion 15b of one of the flanges 15. The flat area 17a of the bracing elements 17 forms an angle β with the web 16, which is approximately 45 degrees. The bracing elements 17 prevent any deformation or overturning of the flanges 15 when the spar 10 is in use, thus optimizing the thickness of the flanges 15 and the web 16.

[0031] A portion of the end 11b of the body 11 is shaped to form a shim 18 for fixing the bar 10 to the rim 104. The shim 18 is thus formed from the material along with the bar 10 and is pierced in its center by the hole 12 allowing the passage of the screw for fixing the bar 10 to the rim 104. The shim 18 has, in its upper part, two flat bearing faces 18a extending in the same plane and intended to cooperate with a flat surface of the rim 104. The two bearing faces 18a are distributed symmetrically on either side of the hole 12.

[0032] With reference to figures 4C et 4D The spacer 18 is hollowed out by the creation of two channels 18b extending substantially along a longitudinal direction of the bar, bypassing the bore 12. The channels 18b have several functions: they allow air to circulate inside the spacer 18, notably under the effect of a forced air circulation imposed by a brake cooling fan, and their presence limits the amount of material of the spacer 18, allowing heat transfer by conduction from the brake rotor discs 106b to the rim 104.

[0033] The channels 18b thus considerably reduce the rate of thermal conduction of the shim 18 and therefore contribute to significantly limiting the heating of the rim 104, in particular at the bearing faces 18a of the shim 18 on the rim 104, while preserving the ability of the shim 18 to transmit the braking torque to the rim 104.

[0034] The bar 10 is manufactured using vertical additive manufacturing along the X-axis, specifically laser beam melting (LBM) of a metal powder bed. The bar 10 is thus produced in a vertical position. This process allows the bar 10 to be manufactured in a single operation from a 3D digital file of said bar 10. The bar 10 is constructed using the selective melting of Inconel alloy powder in a controlled atmosphere. The Inconel alloy powder is spread by a scraper into a bed with a variable thickness of 30 to 90 micrometers. A fiber optic laser beam is directed by mirrors to selectively scan the bed in order to melt the powder in areas defined beforehand by the 3D digital file. The laser beam can, for example, be a YAG (Yttrium Aluminum Garnet) laser beam.

[0035] With an identical fixing interface, the 10 bar allows, compared to the 1 bar, a weight reduction of between 15% and 20% for the bar / shim assembly. Furthermore, the mechanical resistance, and in particular the flexural strength of the bar, is improved.

[0036] 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.

[0037] The body 11 of the bar 10 may not include a shim but a bearing face arranged to receive a shim attached to the bar.

[0038] In order to increase the rigidity of the bar 10 and also to allow the bar 10 to be manufactured by adding a powder so as to obtain the bar horizontally, a portion of the body 11 of said bar 10 may include, as illustrated in the figure 5 , a lattice structure 19, in other words a hollow lattice structure of which an elementary motif is for example a tetrahedron, which serves as a support for a wall of the bar.

[0039] The bracing elements 17 may be of a different shape than those illustrated in the figure 4B .

[0040] Although here bar 10 is made by additive manufacturing, it can also be made by other processes, such as lost wax casting.

[0041] Other powders, other than Inconel brand alloy powder, could be used to manufacture the bar 10, particularly depending on the functional requirements of said bar (steel powder...).

Claims

1. A bar (10) for a braked aircraft wheel (103), the bar being for fitting to a rim (104) of the wheel in order to drive rotor brake disks (106b) in rotation, the bar comprising a substantially rectilinear body (11) having at least one segment (14) including two wings (15) connected together by a core (16) and intended to co-operate with the rotor disks, each wing comprising a lower part (15a) and an upper part (15b) each extending on either side of the core, the bar comprising two brace elements (17) each opposing the overthrow of one of the two wings, characterized in that each of the two brace elements connects an edge of the upper part of one of the two wings to a central portion of the core.

2. A bar according to claim 1, wherein the brace element (17) is a wall extending in a longitudinal direction of the bar between said free edge of the wing (15) and the central portion of the core (16).

3. A bar according to claim 1 or claim 2, wherein a portion of the body (11) forms a fastener wedge (18) for fastening the bar to the rim (104).

4. A bar according to claim 3, wherein said portion of the body forming the wedge includes recesses (18b).

5. A bar according to any preceding claim, wherein a portion of the body includes a trellis structure.

6. A braked aircraft wheel (103) comprising a rim (104) having an inner periphery defining a space for receiving both rotor brake disks (106b) and also bars (10) fastened to the rim in order to constrain the rotor brake disks to rotate with the rim, the wheel being characterized in that the bars are in accordance with any preceding claim.

7. Landing gear (101) including at least one braked wheel (103) according to claim 6.

8. An aircraft (100) including landing gear (101) according to claim 7.

9. A method of fabricating a bar (10) according to any one of claims 1 to 5, said method comprising at least one operation of fabricating the body of the bar by additive fabrication.

10. A method according to claim 9, wherein the additive fabrication operation is performed in such a manner as to obtain the bar in a vertical position.

11. A method according to claim 9, wherein the additive fabrication operation is performed in such a manner as to obtain the bar in a horizontal position and it includes a step of making a trellis structure supporting a wall of the body of the bar.

12. A method according to any one of claims 9 to 11, wherein the additive fabrication operation makes use of laser beam melting on a bed of powder.

13. A method according to claim 12, wherein the powder is an Inconel® alloy powder.