FR3127908A1 - MOTOR VEHICLE WHEEL PROVIDED WITH A VIBRATION TRAP - Google Patents

Abstract

The invention relates to a motor vehicle wheel comprising: - a rim (11), - a tire (12) defining with the rim (11) a circumferential pneumatic cavity (13), and - a vibration trap (25) comprising a plurality of structural resonators (26) arranged outside the tire cavity (13) along all or part of a circumference of the rim (11), - these structural resonators (26) having variations in their mechanical characteristics relative to each other, so that their natural resonant frequencies are distributed over at least one frequency range. Figure 1

Description

MOTOR VEHICLE WHEEL PROVIDED WITH A VIBRATION TRAP

The present invention relates to a motor vehicle wheel provided with a vibration trap. The invention finds a particularly advantageous, but not exclusive, application for improving the acoustic comfort of motor vehicles, in particular vehicles carrying an electric motor.

In a manner known per se, vibratory resonances of the metal structure of the wheel or of a volume of air contained in the tire generate unpleasant noises for the passengers inside the vehicle. It is therefore important to minimize these so-called rolling noises during the overall optimization of the acoustic performance of motor vehicles, in particular vehicles with electric motors which are quieter than internal combustion engines.

In particular, resonances due to natural modes localized at the rim of the wheel produce vibrations and noise which are propagated in the passenger compartment of the vehicle. The order of magnitude of harmful resonant frequencies is typically from 50Hz to a few hundred Hertz. This range of relatively low frequencies is critical for the control of rolling noise because the spectral density of the exciter power of the wheel (tyre-road interaction) is high there.

Among the different eigenmodes directly linked and determined by the structure of the wheel, one or more specific modes called "tilting modes" can be distinguished in particular. This or these modes, which can be described spatially by an oscillating "tilting" movement of the wheel in space, in particular work on the flexibility of the wheel-bearing connection and produce resonances globally in torsion around the plane of the wheel, notoriously damaging to acoustic comfort.

The invention aims to effectively remedy this drawback by proposing a motor vehicle wheel comprising:

- a rim,

- a tire defining with the rim a circumferential pneumatic cavity, and

- a vibration trap comprising a plurality of structural resonators arranged outside the tire cavity along all or part of a circumference of the rim,

- these structural resonators having variations in their mechanical characteristics with respect to each other, such that their natural resonance frequencies are distributed over at least one frequency range.

The invention thus makes it possible, thanks to the structural resonators distributed in the frequency domain and in space, to produce a damping effect on the structure of the wheel and its vibrational modes, in particular the tilting mode(s). The invention thus makes it possible to reduce the level of harmful noises perceived by the driver and the passengers inside the passenger compartment of the vehicle. The invention also has an economic character, insofar as it consists of a passive system made from inexpensive materials.

According to one embodiment of the invention, each structural resonator taken in isolation is a damped mass-spring type system and in that the variations in mechanical characteristics relate to a mass and/or a stiffness of the structural resonators.

According to one embodiment of the invention, a structural resonator comprises a slender support element carrying a mass at a first free end of said slender support element.

According to one embodiment of the invention, a second end of the slender carrier element is fixed to the rim by means of a damping material capable of deforming when the resonator vibrates, such as an organic glue, a bonded elastomer , resin, rubber or silicone material.

According to one embodiment of the invention, an individual damping of a structural resonator is between 1% and 5%.

According to one embodiment of the invention, the structural resonators have slender supporting elements of variable geometry with respect to each other and/or of variable masses with respect to each other.

According to one embodiment of the invention, the natural frequencies of the structural resonators are distributed over at least one range of frequencies surrounding at least one resonant frequency of tilting of the wheel, in particular between 100Hz and 200Hz.

According to one embodiment of the invention, the natural frequencies of the structural resonators are distributed over the frequency range according to a regular frequency step.

According to one embodiment of the invention, an overall mass of the vibration trap is between 1% and 10% of a mass of the rim.

The invention also relates to a motor vehicle comprising a wheel as defined above.

The invention will be better understood on reading the following description and on examining the accompanying figures. These figures are given only by way of illustration but in no way limit the invention.

There is a sectional view of a wheel comprising a vibration trap according to the present invention;

There is a detailed sectional view of part of the wheel comprising a vibration trap according to the invention;

There is a detailed sectional view of a groove made in the rim of the wheel in which a structural resonator according to the invention is placed;

There is a sectional view of an alternative embodiment of the groove of the provided with claws for retaining a structural resonator according to the invention;

There is a schematic representation of a set of structural resonators according to the invention obtained by cutting a sheet of sheet metal;

There is a schematic representation of a sheet of shaped sheet metal in which structural resonators according to the invention are made;

There is a frequency diagram illustrating the attenuation of the vibrations obtained thanks to the vibration trap according to the invention compared with a wheel without such a trap.

Identical, similar or analogous elements retain the same reference from one figure to another.

There shows a sectional view of a wheel 10 comprising a rim 11 generally made of a metallic material. A tire 12 defines with the rim 11 a tire cavity 13 circumferential. To this end, the tire 12 is hooked to the level of shoulders placed at the edges of the rim 11.

The wheel 10 is intended to be fixed to the vehicle by means of a fixing system 15 provided with a wheel pivot 16 belonging to a set of wheels. Wheel 10 cooperates with wheel pivot 16 via a bearing 17.

The wheel 10 is also equipped with a braking system 19 comprising a caliper 22 intended to clamp a disc 23 connected in rotation with the rim 11 to apply a braking torque.

A vibration trap 25 visible in Figures 1 and 2 comprises a plurality of structural resonators 26. By structural resonators 26 is meant resonators made of solid materials as opposed to acoustic resonators also called Helmholtz by men of the art.

In order to avoid interfering with the method of mounting wheel 10, structural resonators 26 are preferably arranged outside circumferential tire cavity 13 along all or part of a circumference of rim 11. Advantageously, the structural elements 26 are also arranged outside a volume occupied by the attachment system 15 of the wheel 10 and the braking system 19. In the example shown, the structural resonators 26 are arranged along a circumference of an internal face of a cylindrical portion of the rim 11 opposite the outer face of the cylindrical portion of the rim 11 facing the tire 12.

The structural resonators 26 have variations in their mechanical characteristics relative to each other such that their natural resonant frequencies are distributed over a frequency range. Advantageously, the natural frequencies of the structural resonators 26 are distributed over at least one range of frequencies surrounding at least one rocking resonance frequency of the wheel 10. The rocking resonance frequency of the wheel 10 is between 100 Hz and 200 Hz. This value depends on the architecture of the wheel and changes with its speed of rotation during its use in the vehicle.

More specifically, each structural resonator 26 taken in isolation is a mass-damped spring type system and the variations in mechanical characteristics relate to a mass and/or a stiffness of the structural resonators 26.

To this end, a structural resonator 26 comprises a slender supporting element 27, such as a blade, carrying a mass 28 at a first free end of said blade 27. A second end of the blade 27 is fixed to the rim 11 by the through a damping material 30 capable of deforming when the resonator vibrates so that the supporting structure vibrates with its added mass.

The damping material 30 may be chosen from: an organic glue, a bonded elastomer, a resin, a material based on rubber or silicone. This makes it possible to perform both the stiffness function and the damping function of each structural resonator 26. The material chosen is preferably able to last over time, among other things to withstand a large number of deformation cycles, and to withstand the surrounding thermal conditions, including high temperature variations. The damping required in the present invention for a resonator is relatively low (but not zero), of the order of a few percent. In practice, this damping has a value between 1% and 5%.

As can be seen on the , the second end of a blade 27 and the damping material 30 may be arranged inside a circumferential groove 31. The groove 31 is defined by a portion of the rim 11 and a lug 32 issuing from this portion. As illustrated by the , claws and/or beads 33 may be provided on the side of the free end of the tab 32 so as to retain the resonators 26 inside the groove 31, which are moreover subjected to a significant centrifugal force during rotation of the wheel 10.

The structural resonators 26 may be added elements fixed to the rim 11. The structural resonators 26 may be obtained by machining a sheet of sheet metal 35, as shown on the . The metal sheet 35 can then be shaped to match the circular shape of the rim 11, as illustrated by the , for example looped back on itself.

As a variant, the structural resonators 26 could be obtained by machining the metal structure of the rim 11. Whatever the embodiment chosen, the structural resonators 26 are preferably arranged along the circumference of the wheel 10 so as to minimize or even to cancel an imbalance of the wheel 10.

With a view to producing variations in the natural frequencies, variations in the stiffness of the structural resonators 26 can be obtained by varying the quantity, volume, arrangement and mechanical characteristics of the material 30 linking the carrying blade 27 to the rim 11, and/or the variations in mass, typically via the volume of material and/or the material used to produce the blades 27 or the masses 28. The materials could for example be chosen from among steel or lead or any other material suitable for the application. The geometry of the blades 27 may also vary.

Due to the frequency distribution of the natural frequencies of the resonators, the latter interfere to produce the effective vibration trap effect of a particular type of trap also called "MTMD" for "Multiple Tuned Mass Damper" in English.

Preferably, the frequency distribution of the natural frequencies of the structural resonators 26 is linear in the target frequency range. Furthermore, the frequency step between two successive natural frequencies of the resonators 26 is preferably regular. Alternatively, the frequency distribution of the structural resonators 26 may not be linear and/or the frequency step may not be regular in certain applications.

The overall mass of the vibration trap 25 can be adapted according to the desired level of efficiency and the mass added to the wheel 10 resulting from the implementation of the invention which it is desired not to exceed. The overall mass of the vibration trap 25 is preferably between 1% and 10% of the mass of the rim 11 so as to limit the impact of the vibration trap on the overall dynamics of the ground connection of the motor vehicle.

For a fixed overall mass of the vibration trap 25, it is more favorable to use a large number rather than a reduced number of structural resonators 26. By way of example, it is possible to use a number of structural resonators 26 comprised between 10 and 100, or even more. Advantageously, the number of structural resonators 26 is between 20 and 50 resonators.

There is a frequency diagram showing that, compared to a vehicle wheel without a vibration trap (cf. curve C1), the wheel 10 according to the invention integrating a vibration trap 25 makes it possible to attenuate the amplitude of the vibrations in a frequency range P located around at least one resonance frequency of wheel tilting, in particular between 100 Hz and 200 Hz (cf. curve C2).

Claims (10)

Motor vehicle wheel (10) comprising:
- a rim (11),
- a tire (12) defining with the rim (11) a circumferential tire cavity (13), and
- a vibration trap (25),
characterized in that said vibration trap (25) comprises a plurality of structural resonators (26) arranged outside the pneumatic cavity (13) along all or part of a circumference of the rim (11),
- these structural resonators (26) having variations in their mechanical characteristics with respect to each other, such that their natural resonance frequencies are distributed over at least one frequency range. Wheel according to Claim 1, characterized in that each structural resonator (26) taken in isolation is a system of the mass-damped spring type and in that the variations in mechanical characteristics relate to a mass and/or a stiffness of the structural resonators (26) . Wheel according to claim 1 or 2, characterized in that a structural resonator (26) comprises a slender carrier element (27) carrying a mass (28) at a first free end of said slender carrier element (27). Wheel according to Claim 3, characterized in that a second end of the slender carrier element (27) is fixed to the rim (11) by means of a damping material (30) capable of deforming when the resonator vibrates, such as an organic glue, a bonded elastomer, a resin, a material based on rubber or silicone. Wheel according to Claim 4, characterized in that an individual damping of a structural resonator (26) is between 1% and 5%. Wheel according to one of Claims 3 to 5, characterized in that the structural resonators (26) have slender carrier elements (27) of variable geometry with respect to each other and/or mutually variable masses (28). compared to others. Wheel according to any one of Claims 1 to 6, characterized in that the natural frequencies of the structural resonators (26) are distributed over at least one frequency range surrounding at least one rocking resonance frequency of the wheel (10), in particular between 100Hz and 200Hz. Wheel according to any one of Claims 1 to 7, characterized in that the natural frequencies of the structural resonators (26) are distributed over the frequency range according to a regular frequency step. Wheel according to any one of Claims 1 to 8, characterized in that an overall mass of the vibration trap (25) is between 1% and 10% of a mass of the rim (11). Motor vehicle comprising a wheel (10) as defined according to any one of the preceding claims.