This application claims the benefit of German Patent Application No. 102023129341.9, filed on Oct. 25, 2023 in the German Patent Office (DPMA), the disclosures of which are incorporated herein by reference in its entirety.
The present invention relates to a fastener for fixing a brake disk to a wheel hub and an axle assembly for a vehicle.
A friction brake for a vehicle, typically, includes a rotor coupled to a wheel of the vehicle and a friction part which is coupled to a body or an axle of the vehicle and configured for being moved into contact with the rotor to generate a frictional force to apply a brake moment to the rotor. For example, in a disk brake, a disk forms the rotor and is coupled to a wheel hub of the vehicle. A disk brake further comprises a brake caliper coupled to a body or an axle of the vehicle, wherein the brake caliper includes a friction pad as the friction part. For braking the wheel, the friction pad is pressed against the disk by an external brake force, which may, for example, be generated aid of hydraulic pressure, to generate a frictional force between the friction pad and the disk.
During a brake operation, in which the friction part is in contact with the rotor, relative motion between the rotor and the friction part occurs which may cause vibrations, mainly of the rotor and the friction pad. Consequently, squeal noise may occur. However, vibration is not limited to the brake as such but also occur in the axle of the vehicle. Since the rotor is connected to the axle a path of force flow exists between the rotor and the axle. Therefore, vibrations in the axle may cause vibration in the brake disk and contribute to vibrational noises generated by the brake disk. Generally, also when a brake as such is thoroughly designed to reduce squeal noises, there may be situation in which squeal noise occurs because the axle and the brake are coupled.
A friction brake for a vehicle, typically, includes a rotor coupled to a wheel of the vehicle and a friction part which is coupled to a body or an axle of the vehicle and configured for being moved into contact with the rotor to generate a frictional force to apply a brake moment to the rotor. For example, in a disk brake, a disk forms the rotor and is coupled to a wheel hub of the vehicle. A disk brake further comprises a brake caliper coupled to a body or an axle of the vehicle, wherein the brake caliper includes a friction pad as the friction part. For braking the wheel, the friction pad is pressed against the disk by an external brake force, which may, for example, be generated aid of hydraulic pressure, to generate a frictional force between the friction pad and the disk.
During a brake operation, in which the friction part is in contact with the rotor, relative motion between the rotor and the friction part occurs which may cause vibrations, mainly of the rotor and the friction pad. Consequently, squeal noise may occur. However, vibration is not limited to the brake as such but also occur in the axle of the vehicle. Since the rotor is connected to the axle a path of force flow exists between the rotor and the axle. Therefore, vibrations in the axle may cause vibration in the brake disk and contribute to vibrational noises generated by the brake disk. Generally, also when a brake as such is thoroughly designed to reduce squeal noises, there may be situation in which squeal noise occurs because the axle and the brake are coupled. It is one of the objects of the present invention to provide improved solutions for reducing acoustic noise generated by brake disk of a brake of a vehicle.
To this end, the present invention provides a fastener in accordance with claim 1, and an axle assembly in accordance with claim 13.
According to a first aspect of the invention, a fastener for fixing a brake disk to a wheel hub includes a shaft, a head formed on an end of the shaft or a counterpart configured for being coupled to the shaft, and at least one damping member integrated into the shaft and/or disposed on a surface of the head or the counterpart.
According to a second aspect of the invention, an axle assembly for a vehicle includes a wheel hub comprising plural attachment openings, a brake disk comprising plural through holes positioned aligned with the attachment openings of the wheel hub, and plural fasteners according to the first aspect of the invention fastening the brake disk to the wheel hub, wherein each fastener extends with its shaft through one of the attachment openings of the brake disk and into one of the attachment openings of the wheel hub, and with its head or counterpart abuts against the brake disk.
It is one of the ideas of the present invention to reduce mutual excitation of vibrations of a brake disk and components of an axle of a vehicle by using fasteners for connecting the brake disk to the axle that comprise a damping member. The damping member is made of an elastically deformable material that is configured to dampen or absorb vibrations, e.g., in a frequency range between 1 kHz and 12 KHz. The damping member is integrated into a shaft of the fastener and, additionally or alternatively, disposed on a surface of a head or a counterpart of the fastener.
The shaft extends longitudinally between a first end and an opposite second end and defines or has a central axis. For example, the shaft may be cylindrical. The damping member, when integrated in the shaft, is integrated into the cross-section of the shaft.
The head, if provided, is formed at the first end of the shaft and protrudes from the circumference of the shaft. For example, the head may have a greater diameter than the shaft. Optionally, the head is integrally formed with the shaft.
The counterpart, if provided, is configured to be coupled to the shaft. This may include that the counterpart has an engagement structure configured to engage an engagement structure formed on an outer circumferential surface of the shaft so that a form fit is achieved between the shaft and the counterpart. Alternatively, the counterpart may also be friction fit to the outer circumferential surface of the shaft, e.g., by crimping, shrinking or similar. When coupled to the shaft, the counterpart protrudes from the circumference of the shaft.
When provided on the head or the counterpart, the damping member is provided on a surface thereof, e.g., as a surface layer, a coating or similar.
In an axle assembly, the brake disk is fixed to a wheel hub by multiple of fasteners as described above. The brake disk, with a first side, may contact a contact surface of the wheel hub. The shaft each fastener extends through a through hole provided in the disk and protrudes into an attachment hole of the wheel hub where the shaft is preferably fixed, e.g., by a form or friction fit or a material joining connection. The head or counterpart abuts against a second side of the brake disk so that the disk is clamped between the head or counterpart and the contact surface of the wheel hub.
The damping elements of the fasteners effectively absorb vibrations. Since the force flow between the brake disk and the wheel hub extends through the fasteners, the damping elements of the fasteners help in reducing transmission of vibrations from the axle to the disk and vice versa. The damping elements of the fasteners help in decoupling the vibrations caused by self-excitation on the brake side, i.e., in the brake disk, and vibrations coming from the axle side. Thus, generation of acoustic noise can be efficiently reduced.
Further embodiments of the present invention are subject to the dependent claims and the following description, referring to the drawings.
According to some embodiments, the shaft may comprise a central recess extending along a central axis of the shaft, wherein the damping member is disposed in the central recess. The damping member has a cross-section corresponding to the cross-section of the central recess and, thus, completely fills the central recess. The central recess may, for example, extend colinear with the central axis.
According to some embodiments, an inner diameter of the central recess may lie in a range of 10% to 70% of an outer diameter of the shaft.
According to some embodiments, the shaft may comprise an annular recess surrounding and extending along a central axis of the shaft, wherein the damping member is disposed in the annular recess. The damping member also has an annular cross-section corresponding to the annular recess and, thus, completely fills the annular recess.
According to some embodiments, the shaft may comprise plural recesses extending along a central axis of the shaft, wherein one damping member is disposed in each of the plural recesses. For example, multiple recesses may be arranged around the central axis.
It should be noted that the plural recesses may also be combined with an annular recess or the central recess. Likewise, it may also be provided that the annular recess is combined with one central recess.
Generally, integrating the damping member into the shaft helps absorbing vibrations in a very efficient way.
According to some embodiments, the head or the counterpart may comprise a contact surface at least partially surrounding the shaft and being oriented along a central axis of the shaft, wherein the damping member is disposed on the contact surface. The contact surface faces the brake disk when the fastener attaches the disk to the wheel hub. That is, the damping member may directly contact the disk when being disposed on the contact surface. Thereby, vibrations can efficiently be absorbed by the damping member.
According to some embodiments, the damping member has a thickness in a range between 0.5 mm and 5 mm.
According to some embodiments, the damping member may be made of a material having a dissipation factor greater or equal than 0.5%, preferably greater or equal than 1%, particularly preferably greater or equal than 3%. The dissipation factor may, for example, be determined in accordance with DIN EN ISO 6721-3 or as disclosed in DE 102 57 056 A1. While steel has a relatively low dissipation factor of 0.1% to 0.3%, Aluminum already has a dissipation factor in a range between 0.5% and 1.2%. Cast Iron has a dissipation factor in a range between 1% and 3%, duroplast material has a dissipation factor in a range between 4% and 12%, hard rubber has a dissipation factor between 5% and 15%, and soft rubber has a dissipation factor in a range between 15% and 35%.
According to some embodiments, the damping member may be made of an elastomer material, in particular, rubber, a thermoplastic or a duroplast material, or cast iron.
According to some embodiments, the shaft and the head or the counterpart are made of a metal material.
According to some embodiments, the shaft comprises an external thread. The external thread may form an engagement structure for coupling the shaft with a nut or for engaging the shaft with an internal thread provided in the attachment opening of the wheel hub.
According to some embodiments, the counterpart may a nut or a sleeve. The nut or the sleeve may be provided with an internal thread for being coupled to the shaft, for example.
According to some embodiments, the axle assembly may comprise a knuckle and a brake caliper mounted to the knuckle. The brake caliper may comprise a friction pad which is movable into contact with the brake disk to apply a friction braking force to the brake disk. For example, the wheel hub may be rotatably mounted to the knuckle, while the brake caliper is stationary fixed to the knuckle. The friction pad may be movable along an axial direction parallel to the rotational axis of the wheel hub. For moving the friction pad, a piston or another actuator may be provided as part of the brake caliper.
The features and advantages described herein with respect to one aspect of the invention are also disclosed for the other aspects and vice versa.
With respect to directions and axes, in particular, with respect to directions and axes concerning the extension or expanse of physical structures, within the scope of the present invention, an extent of an axis, a direction, or a structure “along” another axis, direction, or structure includes that said axes, directions, or structures, in particular tangents which result at a particular site of the respective structure, enclose an angle which is smaller than 45 degrees, preferably smaller than 30 degrees and in particular preferable extend parallel to each other.
With respect to directions and axes, in particular with respect to directions and axes concerning the extension or expanse of physical structures, within the scope of the present invention, an extent of an axis, a direction, or a structure “crossways”, “across”, “cross”, or “transversal” to another axis, direction, or structure includes in particular that said axes, directions, or structures, in particular tangents which result at a particular site of the respective structure, enclose an angle which is greater or equal than 45 degrees, preferably greater or equal than 60 degrees, and in particular preferable extend perpendicular to each other.
For a more complete understanding of the present invention and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings. The invention is explained in more detail below using exemplary embodiments, which are specified in the schematic figures of the drawings, in which:
In the figures like reference signs denote like elements unless stated otherwise.
As schematically shown in
The wheel hub 110 is only schematically shown in
The wheel hub 110 may be rotatably mounted to the knuckle 130, e.g., by means of a bearing 135, as schematically shown in
The wheel hub 110 comprises a plurality of attachment holes 112. In
The brake disk 120, generally, may be a disk shaped part and comprises oppositely oriented friction surfaces 121a, 121b. As exemplarily and only schematically shown in
The brake disk 120 further comprises a plurality of through holes 122. As exemplarily shown in
As schematically shown in
The brake caliper 140 is shown with some details in
In the example of
The shaft 10, generally, extends between a first end 11 and a second end 12 and defines a central axis A10. For example, the shaft 10 may be a generally cylindrical part. As further schematically shown in
The at least one damping member 16, generally, is configured to absorb or dampen vibrations. For example, the damping member 16 may be made of a material having a dissipation factor greater or equal than 0.5%, optionally greater or equal than 1%, further optionally greater or equal than 3%. For example, the damping member 16 may be made of elastomer material, a thermoplastic or a duroplast material, or cast iron.
As schematically shown in
For example, as schematically shown in
The damping member 16 may have a cross-section that corresponds to the cross-section of the central recess 15 and completely fills the central recess 15. The damping member 16 may, for example, be joined to the inner circumferential surface of the central recess 15. For example, the damping member 16 may be filled into the recess 15 in a liquid state and cured or solidified in the recess 15.
The damping member 16 may have a cross-section corresponding to the cross-section of the annular recess 17 and is disposed in the annular recess 17. The damping member 16, thus, completely fills the central recess 15. The damping member 16 may, for example, be joined to the inner and outer circumferential surfaces of the annular recess 17. For example, the damping member 16 may be filled into the recess 17 in a liquid state and cured or solidified in the recess 17.
As shown in
It should be noted that multiple damping members 16 may be integrated into the shaft 10 by combining any one of the examples shown in
As exemplarily shown in
In the fastener 1 exemplarily shown in
Referring again to
Since the fasteners 1 include the damping member 16, vibrations occurring in the disk 120, e.g., due to relative motion between the friction pads 141 and the disk 120 during braking, or occurring in the axle are at least partially absorbed in the damping member 16 which is arranged in the force flow path between the hub 110 and the disk 120. Consequently, mutual excitation of the disk 120 and the hub 110 or, generally, the axle is inhibited Thereby, occurrence of acoustic noise can be reduced.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of at least ordinary skill in the art that a variety of alternate and/or equivalent implementations exist. It should be appreciated that the exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents. Generally, this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102023129341.9 | Oct 2023 | DE | national |