COMPOSITE RIM FOR A VEHICLE WHEEL

Description

Technical field

[0001] The present invention relates to a composite rim for a vehicle wheel, comprising a drum provided with a rim base intended to receive a tire, and a disc provided with a central hub intended to be mounted on a vehicle axle and a plurality of connecting elements extending between the central hub and the drum. Prior art

[0002] Studies have shown that one of the keys to decarbonizing vehicles is to reduce their mass, as the amount of energy required to move a vehicle is highly dependent on its mass. A "vehicle" refers to any vehicle with wheels, used for transporting people and / or freight, on land and in the air.

[0003] 75% of a vehicle's fuel consumption is linked to its mass. The wheel (rim equipped with its tire) is an unsprung mass that is subject to three forces, linked to translational energy, as the wheel moves forward, rotational energy, as it turns, and rebound energy, as it follows the irregularities of the road. Saving 1 kg of unsprung mass is equivalent to several kilos of sprung mass. The wheel rim therefore has a leverage effect in reducing the amount of energy needed to roll the vehicle, and therefore consumption, whether of fossil or bio-sourced fuel, electricity, or hydrogen. Thus, the gain for the environment is immediate.

[0004] In addition to weight optimization, the wheel rim can also provide aerodynamic gains. Indeed, rims and wheel arches contribute 25% of a vehicle's aerodynamic drag. Publication US 2016 / 272000 A1 proposes an aluminum rim whose aerodynamic performance is improved by the design and profile of the spokes and air vents by varying the shape and thickness of an adhesive foam used to fill the space between the spokes of the wheel cover and the spokes of a hubcap.

[0005] Currently, rims are mostly made of aluminum, which has a density of 2.7, which is low for a metal alloy, but which could advantageously be replaced by composite materials, based on carbon fibers and resin, with a density of 1.6, i.e. lighter by 40%. Publications FR 3 050 686 A1 and FR 3 071 772 A1 describe examples of aluminum rims whose mechanical, acoustic and / or aesthetic performance is improved by the addition of one or more reinforcements made of composite materials, without significantly increasing their mass.

[0006] The journal of the 2014 International Chassis Symposium published an article on composite wheel developments (Source: Pfeffer, Peter E., ed. 2014. 5th International Munich Chassis Symposium 2014. Chassis.tech plus. Proceedings. Wiesbaden: Springer Fachmedien Wiesbaden. https: / / doi.org / 10.1007 / 978-3-658-05978-1.)

[0007] Composite rims were developed from the 1980s, first from a mixture of resin and glass fibers, then from resin and carbon fibers which provide more rigidity, and offer a new aesthetic to vehicle wheels. Examples include the following publications: US 4,294,490; US 7,040,714 B2; WO 2010 / 025495 A1; US ​​10,723,172 B2. However, the manufacturing processes are time-consuming and expensive because they are not very automatable, given the complex geometry of the rims. Thus, the price of composite rims is prohibitive and composite rims are reserved for an elite. This type of rim is particularly popular on sports vehicles (Ferrari ®< , McLaren ®< , Lamborghini ®< , etc.).

[0008] There is a need to democratize composite rims to make them accessible to a wider public, to be able to install them on more conventional mass-produced cars, and thus create a lever for improvement on an immediate environmental level. Statement of the invention

[0009] The present invention aims to meet this demand by proposing a new composite rim architecture in which certain functions have been dissociated. Thus dissociated, the constituent and structural elements of the rim become much simpler to manufacture and considerably reduce the complexity and the rate of scrap of raw materials. Similarly, industrial processes can be more easily automated, making it possible to manufacture high-performance rims at high speed, with significant reproducibility and reliability, for a reduced cost price. Other advantages will appear in the remainder of the description.

[0010] For this purpose, the invention relates to a composite rim of the type indicated in the preamble, characterized in that the drum, the web and the flange constitute structural parts, said structural parts being made of composite materials forming an all-composite rim, or one of the structural parts among said drum and said web being made of metallic materials and the other structural part among said web and said drum being made of composite materials forming a hybrid rim.

[0011] This new composite rim architecture, equipped with an additional flange which is attached and secured to the rest of the rim, allows other features to be added, such as: provide the complete rim with additional stiffness / rigidity, as well as precise adjustment of this additional stiffness / rigidity, provide a variation in vehicle behavior, from identical drums and discs, or provide a behavior adjustment (understeer, neutral or oversteer) by different stiffness / rigidity of the flanges between the front and rear axle of the vehicle, provide aerodynamics by adjusting the opening / closing rate of the flange, provide cooling to the braking system, by air extraction or ventilation, by adjusting the geometry of the flange, turbofan type, replace the flange in the event of damage, customize the flange pattern for example for special series, customize the stiffness / rigidity of the rim to absorb variations in power and performance of different versions of a vehicle.

[0012] According to the embodiment variants, the flange is in surface contact with all or part of the connecting elements and with at least one peripheral edge of said drum, said flange being secured to said web and to said drum by structural bonding.

[0013] When said structural parts among the drum and the veil are made of composite materials, they form a single-piece structural assembly.

[0014] When one of said structural parts among the drum and the veil is made of metallic materials and the other structural part among the veil and the drum is made of composite materials, they are secured by fixing members.

[0015] Said flange advantageously comprises a superposition of reinforcement layers having preferred reinforcement directions, the reinforcement directions of said reinforcement layers being crossed relative to each other, and impregnated with a matrix. The reinforcements of said layers can be chosen from the group comprising carbon fibers, mineral, vegetable, artificial, synthetic, metallic, animal fibers, or a combination of at least said fibers.

[0016] At least one of the reinforcing layers of said flange may consist of strands of unidirectional fibers extending wholly or partly radially in said flange.

[0017] Said flange may comprise at least one woven or non-woven external reinforcing layer, said external reinforcing layer being able to define a repetitive, organized or random pattern.

[0018] According to the embodiment variants, said flange may have a thickness of between 0.5 mm and 5 mm, said thickness being constant or variable at least in the radial direction.

[0019] Said flange may comprise an openwork disc wall and / or a plurality of connecting elements, all or part of the connecting elements of the flange matching the shape of the connecting elements of said web.

[0020] The rim may also include metal inserts in the form of annular pieces positioned at the right of the passage holes for the wheel attachment members on the vehicle and / or the central hub.

[0021] The rim may also include, on its outer face, a central recessed area in the shape of a cup, comprising said central hub, said cup being defined by said web and covered by said flange.

[0022] According to the embodiment variants, said drum may include an external collar forming an integral part of the drum or attached to the rim base of said drum. Brief description of the drawings

[0023] The present invention and its advantages will appear better in the following description of several embodiments given as non-limiting examples, with reference to the appended drawings, in which: There Figure 1 is an exploded perspective view of an all-composite rim according to the invention, The Figure 2 is a front view of the rim of the Figure 1 assembly, The Figure 3 is a side view of the rim drum of the Figure 1 , There Figure 4 is a side view of the rim flange of the Figure 1 , There Figure 5 is a section of the rim according to the VV section of the Figure 2 , There Figure 6 is an exploded perspective view of a hybrid rim according to a variant of the invention, The Figure 7is a front view of the rim of the Figure 6 assembly, The figure 8 is a side view of the rim flange of the Figure 6 , There figure 9 is a section of the rim according to section IX-IX of the Figure 7 , There Figure 10 is a graph illustrating the contribution of conical rigidity in % of the all-composite rim according to the invention as a function of a flange added and glued with different thicknesses, in accordance with the conical rigidity measurement test shown schematically, and The Figure 11 is a graph similar to that of the Figure 10 illustrating the contribution of axial stiffness in %, in accordance with the schematic axial stiffness measurement test. Description of the embodiments

[0024] In the illustrated embodiments, identical elements or parts bear the same reference numbers. In addition, terms that have a relative meaning, such as vertical, horizontal, right, left, front, rear, above, below, etc., must be interpreted under normal conditions of use of the invention, and as shown in the figures. The X, Y and Z axes are defined by an orthonormal reference frame illustrated in Figure 1. Furthermore, the geometric positions indicated in the description and the claims, such as "perpendicular", "parallel", "symmetrical" are not limited to the strict sense defined in geometry, but extend to geometric positions which are close, that is to say which accept a certain tolerance in the technical field considered, without influence on the result obtained. This tolerance is notably introduced by the adverb "substantially", without this term necessarily being repeated before each adjective.

[0025] With reference to the figures, the rim 1, 1' according to the invention comprises at least the following structural parts: a drum 2 with a central axis Y provided with a rim base 3 arranged to receive and hold a tire (not shown) both axially and radially, and to allow it to be maintained under pressure, a disc 4, 4' provided with a central hub 5 coaxial with the central axis Y, intended to be mounted on a vehicle axle (not shown) and a plurality of connecting elements 6 ensuring the connection between the central hub 5 and the drum 2, and providing rigidity to the rim, and an attached flange 7, which at least partially covers the disc 4, forms the outer face of the rim, and may include a central opening 8 in line with the central hub 5; these structural parts being secured to each other to form a single-piece structural rim 1, meeting the corresponding specifications.

[0026] By "structural part" we mean a part intended to support and transmit or transfer loads.

[0027] All structural parts of the rim 1 may be made of composite materials, in accordance with the embodiment illustrated in the figures 1 to 5 We then speak of a full composite or “full composite” or “full carbon” rim in English.

[0028] Alternatively, one of the structural parts of the rim 1, among the drum 2 and the disc 4, may be made of metal, such as aluminum alloy or the like, while the other part among the disc 4 and the drum 2 is made of composite materials. This is then referred to as a hybrid “composite / metal” or “composite / aluminum” rim 1'. However, in the description, the term “composite rim” is generic and covers the all-composite rim and the hybrid rim. The variant embodiment of the rim 1' illustrated in figures 6 to 9 concerns a rim whose 4' disc is made of metal and the 2' drum is made of composite, without this variant being limiting, since the reverse is possible.

[0029] In all embodiments, the flange 7 is made of composite materials, and is designed to match all or part of the shapes of the web 4, 4', in order to be secured in whole or in part to the connecting elements 6 and, depending on the variants, to the central hub 5 of the web as well as to the drum 2 to form a single-piece structural rim 1, 1'.

[0030] In the context of the invention, the term "composite material" should be understood to mean a material which generally comprises a fiber-based reinforcement preform, impregnated with a polymer-based matrix, and supplemented where appropriate with fillers and / or additives. The reinforcement preform may have different architectures such as wick, sheet, unidirectional, multidirectional, fabric, knit, non-woven, etc. The fibers may be continuous or discontinuous, short or long, chosen from carbon fibers, mineral, plant, artificial, synthetic, metallic, animal fibers, a combination of all or part of these fibers, or fibers of any other nature commonly used in composite materials. The polymers may be thermoplastic resins or thermosetting resins, commonly used in composite materials, or a combination of both types of resins.

[0031] More specifically, carbon fibers will be favored because they offer a very good compromise of rigidity and strength in relation to mass, and are already widely used in all structural applications requiring high rigidity and strength, such as chassis-shells, door pillars, etc.; also associated with a thermosetting epoxy resin which has good mechanical and impact resistance characteristics allowing the production of high-performance structural parts (vehicles and racing sailboats, aeronautics).

[0032] In the first embodiment with reference to the figures 1 to 5, the structural parts formed by the drum 2 and the web 4 are made of composite materials using known manufacturing processes which will not be detailed, and which make it possible to produce a single-piece structural assembly “drum + web” 10 meeting the specifications in terms of rigidity, strength, fatigue resistance and impact resistance, for a mass saving of approximately 40% compared to an aluminum rim (density of aluminum: 2.7 / composite density “carbon and epoxy”: 1.6). Non-limiting examples include dry or wet manufacturing processes, non-corrugated multiaxial reinforcement processes called NCF (Non-crimp fabrics), fiber placement processes called AFP (Automatic Fiber Placement) or TFP (Tailored Fiber Placement), etc.

[0033] Drum 2 comprises, with reference to the Figure 3and in a known manner, a solid cylindrical central part, with axis Y, more or less hollow, constituting the rim base 3 designed to receive a tire, bordered by an inner rim bead 11 and an outer rim bead 12 on which the tire rests, then terminated by an inner rim flange 13 and an outer rim flange 14 blocking the tire axially. The drum 2 also comprises a through hole 15, arranged between the rim base 3 and the outer rim bead 14, designed to receive the tire valve (not shown).

[0034] The drum 2 can be made in one part or in several parts if it is desired to simplify the manufacturing process to automate it, in particular when it is made of composite materials. For example, it can be split into two parts: a first part comprising the rim base 3, the inner rim bead 11 and the inner rim flange 13, and a second part comprising the outer rim bead 12 and the outer rim flange 14, hereinafter called the “outer collar”. In this case, the two parts can be manufactured separately and secured to each other by fixing members (not shown) or any other assembly method compatible with the materials chosen for the parts of the drum.

[0035] Veil 4 includes, with reference to the figures 1 , 2 And 5and in a known manner, an openwork disc portion, with an axis Y, provided with a central zone more or less re-entrant in the shape of a bowl 16, and the central hub 5 provided to receive a vehicle axle. The bottom of the bowl 17 comprises passage holes 18 for fixing members (not shown) arranged to fix the wheel on the vehicle, these passage holes 18 being regularly distributed around the central hub 5. The disc 4 further comprises a plurality of connecting elements 6, such as sticks also called spokes, extending in whole or in part radially in the remaining disc portion from the bowl 17 and regularly distributed. The connecting elements 6 may have any other shape than that of sticks and / or may extend in different directions, both radial and transverse, the essential thing being to ensure the connection between the hub 5 and the drum 2. The connecting elements 6 delimit ventilation openings 19 between them.The ventilation openings 19 allow the heat generated by the braking of the wheels to be dissipated. The connecting elements 6 may have a substantially square, truncated cone or polygonal section, with more or less rounded angles. The connecting elements 6 may be solid or hollow. They may also comprise a rigid core, for example made of thermosetting epoxy resin foam or any other equivalent low-density material (density of the epoxy resin foam: 0.2 to 0.4). The ends of the connecting elements 6 are secured to the drum 2 during the manufacture of the single-piece structural assembly “drum + sail” 10.

[0036] The flange 7 comprises, with reference to the figures 1 , 2 , 4 And 5, an architecture similar to that of the veil 4, without this example being limiting. Thus, it comprises an openwork disc part, with axis Y, provided with a central zone more or less re-entrant in the shape of a bowl 20, the central opening 8 provided in the bottom of the bowl 21, and a peripheral edge 23. The bottom of the bowl 21 comprises passage holes 22 arranged to be in alignment with the passage holes 18 of the veil 4 for members for fixing the wheel to the vehicle. The flange 7 further comprises a plurality of connecting elements 24, such as branches, extending wholly or partly radially in the remaining disc part between the bowl 20 and the peripheral edge 23, delimiting between them ventilation openings 25 allowing the dissipation of heat.The periphery of the connecting elements 24 and the ventilation openings 25 comprises an edge 26 folded inwards to create a U-shaped interlocking section, and to at least partially match the three-dimensional shape of the connecting elements 6 of the web 4.

[0037] In other variants not shown, the flange 7 does not have an architecture identical to that of the web 4, and may differ by the percentage of ventilation openings 25 in the disc portion, the shape and arrangement of the ventilation openings 25, the shape, orientation and arrangement of the connecting elements 24, the presence or absence of a cup 20, the presence or absence of a central opening 8, etc. In all cases, the flange 7 is designed as a second skin arranged to be in surface contact with all or part of the web 4 and to extend to the outer rim flange 14 of the drum 2. The flange 7 is not intended to replace all or part of the functions of the drum 2. The section of the flange 7 shown in FIG. Figure 5shows the flange 7 which matches the three-dimensional shapes of the web 4 and extends from the central hub 5, passing through the cup 16, the connecting elements 6, to below the outer rim flange 14 of the drum 2. The flange 7 can conceal the web 4, 4' in its entirety, or on the contrary, leave some parts of the web 4, 4' visible, in particular when the web 4' is made of metallic materials, to give a particular aesthetic to the rim 1'.

[0038] The flange 7 is attached and secured to the single-piece structural assembly “drum + disc” 10 by structural bonding on all or part of its contact surface with the disc and the drum, as well as on the inner and outer periphery, this structural bonding having the function of transmitting mechanical forces. A high-performance structural adhesive, such as an epoxy resin, is chosen in particular. This adhesive must resist shearing and impacts, and guarantee the integrity of the rim 1 to avoid any risk of detachment of the flange 7, regardless of the conditions of use and climate. In addition, the flange 7 may be detached using different methods, one of which consists of depositing the adhesive on a bonding primer or a hot-melt adhesion promoter, allowing the voluntary detachment of the flange 7 under high temperature.The rim 1 according to the invention then becomes repairable, without needing to requalify the rim 1.

[0039] The flange 7 is made of composite materials using known manufacturing processes which will not be detailed, and which make it possible to produce a flange 7 combining strength, lightness and aesthetics. The processes and materials mentioned previously for the drum 2 and the web 4 may of course be suitable. The flange 7 has the advantage of having a relatively flat shape, its geometric shape being less complex and comprising fewer angle variations than the web 4. Thus, its manufacturing process can be simplified and easily automated. It is in particular possible to use continuous preforms, which is impossible for the manufacture of the web 4 which requires an assembly of sub-preforms.

[0040] The flange 7 comprises, by way of non-limiting example, a superposition of reinforcing layers, also called “plies”, having several preferred reinforcement directions. The reinforcement directions of the reinforcing layers are preferably crossed relative to each other, and the crossing angle may be between 0° (excluded) and 90°. At least one of the reinforcing layers may consist of strands of unidirectional fibers extending radially in the direction of the connecting elements 24 of the flange, from the cup 20 to the peripheral edge 23.

[0041] The flange 7, which forms all or part of the outer face of the rim 1, allows the rim to be customized as desired, by playing either on the composite materials themselves of the outer layer of the flange 7, or by adding an aesthetic treatment. For example, this outer surface can be painted for an economical rim. It can also be made up of at least one specific reinforcing layer, in which the fibers are arranged together in a particular pattern for a more aesthetic rim. For example, the reinforcing layer can be woven according to a specific weave chosen from the group comprising a twill, satin, plain, jacquard, or can be non-woven. The reinforcing layer can be designed to create a repetitive, organized or random pattern, without these examples being limiting.

[0042] As an example, but not a limiting one, the flange 7 may comprise three plies of carbon fabric of 400g / m 2< and 0.4mm each, finished with a ply of 2x2 twill carbon fabric of 200g / m 2< and 0.2mm to give the rim a classic carbon appearance (“carbon look” in English). The number, weight and thickness of each ply may vary depending on the specifications.

[0043] The flange 7 can be supplemented with specific treatments, particularly on its outer face, to provide protection against ultraviolet radiation, grease, brake fluid, bird droppings, etc., in accordance with existing treatments.

[0044] The flange 7 has a relatively small thickness determined by the number and thickness of each fold, this thickness being able to be between 0.5 mm and 5 mm, without these values ​​being limiting. The thickness of the flange 7 can be constant in the radial direction from the center to the peripheral edge 23 or variable gradually or not in certain zones such as around or in the bowl 20 where this thickness can be more or less significant.

[0045] The rim 1 according to the invention, with particular reference to the Figure 1 , also includes metal inserts 27, 28 arranged in line with the passage holes 18, 22 for the fixing members 29 ( Figure 6) of the wheel on the vehicle and / or of the central hub 5. These metal inserts 27, 28 allow in particular the transmission of the compression forces of the fixing members. They consist of annular parts, made for example of aluminum alloy or similar, anodized or not, molded and / or machined, fitted and glued in the corresponding bores. The insert 28 of the central hub 5 also allows the fixing of a cap (not shown) bearing for example the vehicle logo.

[0046] In the variant embodiment of the hybrid rim 1', with reference to the figures 6 to 9, the drum 2 is made of composite materials as in the previous example and will not be described again, while the 4' plate is made of metallic materials, for example aluminum alloy, sheet metal or any other suitable metallic material, by casting, forging, stamping and / or machining. The added flange 7' is also made of composite materials as in the previous example. The hybrid rim 1', less efficient in terms of mass saving, nevertheless allows for management of rigidities and can therefore prove interesting, knowing that it offers good performance at a lower cost.

[0047] The metal web 4' is structured in a similar manner to the composite web 4 as described previously, and the similar constituent parts bear the same reference number. However, it has a different aesthetic, linked to the shape, arrangement and distribution of the connecting elements 6 and the ventilation openings 19. In this example, the connecting elements 6 are V-shaped, the tip of the V being directed towards the central hub 5 and the two branches of the V being directed towards the drum 2. The branches of each V may be hollowed out in whole or in part to reduce the mass. The connecting elements 6 delimit between them and between the branches of each V the ventilation openings 19. In this example, the opening rate of the web 4' is greater than the opening rate of the web 4 of the previous example.

[0048] The three-dimensional shape of the veil 4' can thus be optimized in particular at the level of the connecting elements 6 and the bowl 16 to seek the best “design / mass / performance” compromise. In addition, the connecting elements 6 being partly hidden by the flange 7', their shape, less subject to aesthetics, can be optimized to achieve a good mass / mechanical strength ratio. Their section can be chosen from the group comprising at least the following shapes: square, round, annular, polygonal, truncated, ribbed, U-shaped, I-shaped, T-shaped, without this list being exhaustive.

[0049] In this variant, the web 4' is secured to the drum 2 by means of fixing members (not shown) for example screw-on, or any other assembly method, making it possible to secure the ends of the connecting elements 6 to the peripheral edge of the drum 2. The outer rim bead 12 of the drum 2 can be thickened and / or reinforced to integrate the fixing means allowing the transmission of forces between the web 4' and the drum 2.

[0050] The composite flange 7' is structured in a similar manner to the composite flange 7 as described previously, and similar constituent parts bear the same reference number. However, it has a different aesthetic, linked to the shape, arrangement and distribution of the connecting elements 24 and the ventilation openings 25. In this example, the connecting elements 24 comprise V-shaped branches, arranged opposite the connecting elements 6 of the web 4', and partially closed sectors between two consecutive Vs. The connecting elements 24 delimit between the branches of each V and in their partially closed sectors, the ventilation openings 25. The ventilation opening 25 provided in each partially closed sector comprises an asymmetrical V-shaped recess extended to the right of the V by a curved slot. In this example, the opening rate of the flange 7' is lower than the opening rate of the flange 7 of the previous example.

[0051] In a variant not shown of the hybrid rim 1', it is the drum 2 which is made of metallic materials, while the disc 4 is made of composite materials.

[0052] During the tests, it was surprisingly discovered that the addition of the flange 7, 7' as a second skin to the 4, 4' web of the rim 1, 1', makes it possible to improve the mechanical properties of the rim, by playing on the structural variations of said flange 7, 7'. Primarily 70 to 90% of the mechanical properties of the rim are achieved by the 4, 4' web associated with the drum 2, while the remainder is achieved by the flange 7, 7'. By playing on the rigidities brought to the rim 1, 1' by the flange 7, 7', the behavior of the vehicle when rolling becomes more stable, and an aerodynamic gain is observed, due in particular to its design and its opening rate which can be reduced compared to that of the 4, 4' web.Thus, the manufacture of the flange 7, 7' as a separate part, having a simplified geometry, makes it possible to modify its manufacturing parameters relatively easily to adjust the mechanical performance of the rim 1, 1', and in particular at least one of its rigidities, such as radial rigidity, axial rigidity or conical rigidity (see . figures 10 to 11 ). Indeed, the added flange 7 behaves like a multitude of stays stretched between the diametrically opposite ends of the rim 1, 1', generating a multitude of lever effects which automatically compensate for the deformations of the rim, in particular in the axial direction. In other words, the flange 7, 7' is a second skin added to the structure of the rim 4, 4', which works mainly in tension / compression, which is well suited to a design of the flange 7, 7' in composite materials, in particular carbon fibers.

[0053] The manufacturing parameters of the flange 7, 7' that can be varied are numerous, and we can cite in particular: the modulus of the reinforcing fibers in each ply, the angle of intersection of the plies with each other, the number of plies which determines the thickness of the flange, the distribution of the plies which makes it possible to vary the thickness of the flange in the radial direction, the bonding surface, the type of structural adhesive and the thickness of adhesive between the flange 7, 7' on the one hand and the web 4, 4' and the drum 2 on the other hand, the opening rate. The list of modifiable manufacturing parameters is not exhaustive.

[0054] However, since the 7.7' flange is made of composite materials and must be thin enough to not add too much mass, the main parameter to determine is the thickness of the flange, which leads to the choice of the type of fibers, their quantity and their orientation to obtain the desired levels of rigidity. This thickness is obtained by stacking different plies, which can have different weights, therefore different thicknesses, for example from 0.1mm to 0.4mm. The stiffness gains of the all-composite rim 1, as illustrated in the figures 10 And 11 , were evaluated over a thickness range of up to 2.8mm, without this value being limiting.

[0055] THE figures 10 And 11illustrate in the form of graphs, measurements carried out on test benches allowing to evaluate the contribution of rigidity in percentage ("%" on the ordinate) of the rim 1 of all composite structure, according to a flange 7 reported and glued of different thicknesses ("mm" on the abscissa). The calculation of the rigidities is done by the ratio between the deflection D of the rim fixed on a shaft and the load F applied to obtain this deflection. To obtain the conical rigidity according to the Figure 10 , a load F perpendicular to the central axis Y of the rim 1 is applied, on a point belonging to a shaft fixed to the central hub 5, and the deflection D of the rim is measured at this point. To obtain the axial rigidity according to the Figure 11, a load F parallel to the central axis Y of the rim 1 is applied to a peripheral point of the drum 2, and the axial deflection D of the rim is measured at this point. To obtain the radial rigidity (not shown because it is less obvious), a load perpendicular to the axis of the rim 1 is applied to a point on the inner rim bead 11 of the drum 2, and the radial deflection of the rim is measured at this point.

[0056] There Figure 10 illustrates the percentage improvement in the conical rigidity of rim 1. We observe that the curve which connects the measurements is substantially linear from 0mm to 1.6mm going from a gain of 0% to 18%, bends slightly from 1.6mm to 2mm going from a gain of 18% to 25%, and rounds off from 2mm to 2.8mm going from a gain of 25% to 27%.

[0057] There Figure 11illustrates the percentage improvement in the axial stiffness of rim 1. We observe that the curve which links the measurements is substantially linear from 0mm to 1.6mm going from a gain of 0% to 23%, and bends slightly from 1.6mm to 2.8mm going from a gain of 23% to 38%.

[0058] These graphs clearly illustrate that flange 7 and the thickness of this flange play a significant role in improving the stiffness of rim 1. The choice of the thickness of flange 7 will therefore be a compromise between the different stiffnesses of rim 1 desired. By adjusting the stiffnesses between the front rims and the rear rims, it is thus possible to modify the driving behavior of a vehicle and improve its stability. The link between rim stiffness and the rolling stability of a vehicle has been the subject of the following study: Hirano, A., "Study on Wheel Stiffness Considering Balance between Driving Stability and Weight," SAE Int. J. Commer. Veh. 8(1):2015, doi:10.4271 / 2015-01-1755.

[0059] By adjusting all or part of the manufacturing parameters of the 7.7' flange, tests have shown that it is possible to adapt the 1.1' rim to the needs of the car and to obtain performances equivalent to, or even superior to, conventional forged aluminum alloy rims.

[0060] The present invention is of course not limited to the exemplary embodiments described but extends to any modification and variants obvious to a person skilled in the art within the limits of the appended claims. Furthermore, the technical characteristics of the different embodiments and variants mentioned above may be, in whole or in part, combined with each other.

Claims

1. A composite rim (1, 1') for a vehicle wheel, comprising a drum (2) provided with a rim bottom (3) intended to receive a tire, and a web (4, 4') provided with a central hub (5) intended to be mounted on a vehicle axle and with a plurality of connecting elements (6) extending between the central hub (5) and the drum (2), the rim further comprising: a composite and attached flange (7, 7'), which at least partially covers said web (4, 4'), forms all or part of the outer face of the rim, matches all or part of the shapes of said web (4, 4'), and is secured all or part to the connecting elements (6) of said web and to said drum (2) to form a reinforced one-piece structural rim, said flange (7, 7) being arranged to adjust the mechanical performance of said rim (1, 1'), the rim being characterised in that the drum (2), the web (4, 4 ') and the flange (7, 7') constitute structural parts, said structural parts being made of composite materials forming an all-composite rim, or one of the structural parts among said drum (2) and said web (4, 4') being made of metal materials and the other structural part among said web and said drum being made of composite materials forming a hybrid rim.

2. The rim according to claim 1, characterised in that said flange (7, 7') is in surface contact with all or part of the connecting elements (6) and with at least one peripheral edge of said drum (2), said flange (7, 7') being secured to said web (4, 4') and to said drum (2) by structural bonding.

3. The rim according to claim 1, characterised in that, when said structural parts among said drum (2) and said web (4) are made of composite materials, they form a one-piece structural assembly (10).

4. The rim according to claim 1, characterised in that, when one of said structural parts among said drum (2) and said web (4') is made of metallic materials, and the other structural part among said web and said drum is made of composite materials, they are secured by fixing members.

5. The rim according to claim 1, characterised in that< / b> said flange (7, 7') comprises a superposition of reinforcement layers having preferential reinforcement directions, the reinforcement directions of said reinforcement layers being crossed with respect to each other, and impregnated with a matrix, and in that the reinforcements of said layers are selected from the group comprising carbon fibres, mineral, plant, artificial, synthetic, metal, animal fibres, or a combination of at least said fibres.

6. The rim according to claim 5, characterised in that at least one of the reinforcing layers of said flange (7, 7') consists of unidirectional fibre rovings extending all or part radially in said flange (7, 7').

7. The rim according to claim 1, characterised in that said flange (7) comprises an outer surface comprising at least one woven or non-woven reinforcing layer, said reinforcing layer defining a repetitive, organised or random pattern.

8. The rim according to any one of claims 5 to 7, characterised in that said flange (7) has a thickness of between 0.5 mm and 5 mm, said thickness being constant or variable at least in the radial direction.

9. The rim according to claim 1, characterised in that said flange (7) comprises a perforated disc wall and / or a plurality of connecting elements (24), all or part of the connecting elements (24) of the flange (7) matching the shape of the connecting elements (6) of said web (4, 4').

10. The rim according to any one of the preceding claims, characterised in that it comprises metal inserts (27, 28) in the form of annular parts positioned in line with the passage holes (18, 22) for members for fixing the wheel to the vehicle and / or the central hub (5).

11. The rim according to any one of the preceding claims, characterised in that it comprises, on its outer face, a bowl-shaped recessed central area (16, 20), comprising said central hub (5), said bowl (16, 20) being defined by said web (4, 4') and covered by said flange (7, 7').

12. The rim according to any one of the preceding claims, characterised in that said drum (2) comprises an outer collar (12, 14) integrally with the drum (2) or attached to the rim bottom (3) of said drum (2).