Patent Application
20240369113
This application is based on and claims priority under 35 U.S.C. ยง 119 to German Patent Application No. 102023111503.0, filed on May 3, 2023 in the German Patent and Trade Mark Office, the disclosures of which are incorporated herein by reference.
The invention relates to a brake component assembly for a vehicle wheel brake. In particular, a brake component assembly for a vehicle wheel brake that is configured as a disc brake is disclosed. The vehicle may be a road vehicle, such as car, a truck or a bus.
Vehicle wheel brakes are typically provided to brake individual wheels of a vehicle. They comprise a plurality of components, in particular components that are movable relative to one another. In case these components contact one another or at least indirectly support one another during their relative movement, forces may be transmitted between these components. This may result in vibrations and in acoustic noises being generated. These noises may in particular occur in form of squeal noises in a frequency range between 1000 Hz and 16000 Hz.
Several attempts have been made to adapt vehicle wheel brakes and in particular their moving components to limit the generation of such noises. Typically, these attempts focus on noise-generating effects occurring during braking as well as at the beginning of a braking operation (e.g. when displacing a brake pad towards a brake disc).
Typical approaches to suppress noise generation include providing a shim on a back plate of a brake pad as e.g. disclosed in DE 10 2014 213 410 A1. Moreover, it is known to provide chamfers on contact surfaces of brake pads contacting a brake disc, slots within such contact surfaces as well as modifications of a friction material or underlayer material used in brake pads.
It has been observed that such existing solutions are insufficient to reliably suppress acoustic noises when operating a vehicle wheel brake.
Accordingly, it is an object of this invention to improve operating characteristics of a vehicle wheel brake, in particular with respect to a generation of vibrations and an associated generation of acoustic noise.
This object is solved by the subject matter according to the attached independent claim. Advantageous embodiments are set out in the dependent claims, in this description and in the figures.
Accordingly, a brake component assembly for a vehicle wheel brake is suggested, the brake component assembly comprising a first component and a second component, wherein the first and second component are movable relative to one another when engaging and releasing the vehicle wheel brake. A self-lubricating material is provided that is configured to lubricate at least one pair of surfaces that (e.g. slidingly) contact one another and that are movable relative to one another when moving the first and second component relative to one another. The self-lubricating material is elastically deformable, e.g. by contact forces occurring between (or forces transmitted in between) the first component and second component, e.g. when operating the vehicle wheel brake. That is, the self-lubricating material may elastically deform under normal operating conditions, e.g. when engaging and/or releasing the brake pad.
The brake component assembly may comprise any further and in particular all further components for forming an entire vehicle wheel brake. This may e.g. include any and in particular all of: a brake caliper housing, a brake pad carrier, a brake disc and at least one brake pad.
The surfaces of the pair of surfaces may be comprised by the first and second component (e.g. a first surface of said pair by the first component and a second surface of said pair by the second component). Alternatively, at least one of the surfaces of the pair of surfaces may be comprised by an additional component (e.g. a third component of the brake component assembly and/or a clip discussed below). Said additional component may e.g. be arranged in between the first and second component. For example, said additional component may contact or support at least one of the first and second component and/or transmit forces between the first and second component. According to below discussed embodiments, said additional component may be a clip that is e.g. held at one of the first and second component and is movable relative to the respective other one of the first and second component.
The self-lubrication may include that a lubricant (e.g. a lubricating film) is provided at and/or by the lubricating material when operating the vehicle wheel brake. This lubricating film may be upheld and/or frequently renewed by the self-lubricating material over an operating life of several months or years. For example, the self-lubrication may include that the self-lubricating material produces and/or discharges a lubricating film during operation of the brake component assembly. For example, the self-lubricating material may comprise an intrinsic self-lubrication effect (e.g. an intrinsic capability to produce the lubricating film discussed above).
On the other hand, it may not be necessary (and may generally not be part of the self-lubrication disclosed herein) to provide a lubricant deposits or lubricant reservoirs at external component surfaces. In the prior art, such lubricant deposits may e.g. be disposed in form of grease or oil deposits having large volumes. At least according to embodiments of this disclosure, the self-lubricating material may rather be a stiff and/or non-fluid material. Over a long operating life (e.g. steadily and/or little by little) the self-lubricating material may exude, release or discharge a lubricant film, without necessarily requiring external lubricant deposits directly add its surfaces. Nonetheless, the presently disclosed solution may be provided in combination with such external lubricant deposits.
To sum up, the self-lubricating material may inherently comprise an e.g. integrated lubricant that is releasable over time, instead of an external lubricant disposed on one of its external surfaces.
Optionally, the self-lubricating material may comprise a degradable matrix or a degradable base material including lubricating particles (e.g. spatially dispersed lubricant particles). The latter, when exposed, may produce the lubricating film. Additionally or alternatively, the self-lubricating material may e.g. under mechanical pressure release a lubricant to produce the lubricant film. For example, the self-lubricating material may be a rubber material (or another elastically deformable material, in particular an elastomeric material) exuding (and in particular steadily renewing) a lubricating film over time. One example of such a self-lubricating materials are self-lubricating silicones, such as liquid silicone rubbers in which optionally a lubricant may be injected. Other examples of self-lubricating materials include self-lubricating plastics, such as UHMW-PE (ultra high molecular weight polyethylene) with oil or wax added; Nylon with solid oil, wax or molybdenum added; Teflon with molybdenum added.
It has been observed that by way of the solution disclosed herein, vibrations and acoustic noises can significantly be reduced. This applies to the start of a braking process, e.g. when a displacement of a brake pad (as one example of the first component) relative to a brake pad carrier (as one example of the second component) sets in, as well as during braking. Yet, as an advantage over prior art solutions, the present solution may also help to reduce vibrations and acoustic noises when displacing the brake pad in the opposite direction after braking, that is when releasing the vehicle wheel brake. Specifically, it has been observed that during this releasing displacement, uncontrolled relative movements and in particular tilting movements may occur between causing vibrations and acoustic noises. Specifically, flutter vibrations may occur when releasing the brake. The present solution helps to suppress such flutter vibrations. Additionally or alternatively, it may at least somewhat dampen unintended contact forces between the components when releasing the brake due to the disclosed self-lubricating effect and elastic deformability.
According to one embodiment, the self-lubricating material is comprised by a coating arranged at least one of the surfaces of the pair of surfaces. For example, the coating may be applied to the component during production and before arranging the component in the brake component assembly. The coating may directly be provided at the respective component and cover part of an external surface thereof. The coating may thus form an integral and/or non-removable part of the respective component. Providing the self-lubricating material as a coating may help to reduce overall part numbers and production costs. Also, it reliably positions the self-lubricating material directly at one of the components, so that relative movements between the self-lubricating material and this component are prevented.
In one example, the self-lubricating material is comprised by at least one clip that comprises one of the surfaces of the pair of surfaces and that is held at one of the first component and second component. The clip may be separately produced, i.e. may be separate from the respective one of the first and second component. The clip may e.g. be fixed to the respective one of the first and second component at which it is held. The fixation may include a mechanical fixation, e.g. by means of mechanical fixing elements, such as rivets or screws. Additionally or alternatively, the fixation may include a force fit (e.g. by elastically clamping the clip to the respective one of the first and second component) and/or a fixation based on an adhesive connection formed between the clip and the component.
The clip may have a first surface facing the first component and a second surface facing the second component. At least one of said first and second surfaces may form a surface of a pair of surfaces discussed above.
By providing the self-lubricating material at a separate clip, changes to existent component designs can be limited. Also, the clip can be independently replaced to restore a self-lubricating effect.
According to one embodiment, one of the first component and second component is a brake pad and the clip is arranged at the brake pad and is jointly displaceable therewith. For example, the brake pad may have at least one guiding projection that is receivable in a guiding recess of a brake pad carrier. The guiding projection may also be referred to as a guiding ear. It may be provided at a lateral surface of the brake pad. It may e.g. project in a plane extending in parallel to a contact surface of the brake pad contacting a brake disc. The clip may be arranged at such a guiding projection. In particular, it may at least partially surround the guiding projection and/or receive at least part of said guiding projection.
In one example, the clip has C-shape, in particular wherein the C-shape may be angled (e.g. have sharp corners) or curved. At least part of the brake pad and in particular of its optional guiding projection may be arranged within a recess formed by said C-shape.
The clip may act as a known pad clip helping to limit vibrations between the brake pad and brake pad carrier. Additionally or alternatively, the clip may act as a pad spring and also provide a brake pad restoring effect. Specifically, when configured as a pad spring, the clip may be configured to generate a restoring force for displacing the brake pad back into its original position when releasing the brake. This may be achieved by the clip having at least one deformable section that elastically deforms in accordance with a displacement of the brake pad towards a brake disc. This elastic deformation may generate a restoring force for lifting the brake pad off of the brake disc after braking.
Additionally or alternatively, the clip comprising the self-lubricating material may be provided in addition to a known pad clip or known pad spring. For example, the clip disclosed herein may be received in such a known pad clip or pad spring together with a section of the brake pad at which it is arranged.
According to a further embodiment, one of the first component and second component is a brake pad carrier and the clip is arranged at the brake pad carrier. The brake pad carrier may generally be configured to carry and/or guide at least one brake pad, e.g. during its displacement towards and away from a brake disc of the vehicle wheel brake. For example, the brake pad carrier may comprise a guiding groove in which a guiding projection as discussed above is received. The brake pad carrier may be stationary, e.g. due to being fixed to an axle component, such as an axle knuckle. A brake caliper housing may move relative to the brake pad carrier while displacing at least one brake pad.
When arranged at the brake pad carrier, the clip may, for example, at least partially be received in a guiding groove thereof. Generally, the clip may be arranged so as to be able to contact and in particular receive at least a section of the brake pad, e.g. of its guiding projection. Again, the clip may be C-shaped. A closed side of said C-shape may face the brake pad carrier, whereas an open side thereof may face the brake pad, in particular to receive at least part of the latter.
Arranging the clip at any of the brake pad and brake pad carrier reliably suppresses and vibrations and acoustic noises. In one example, both of the brake pad and brake pad carrier comprise a respective clip. In this case, each clip may comprise one of the surfaces from the pair of surfaces, so that these clips may in particular contact one another.
According to one example, the self-lubricating material is provided at both of the surfaces of the pair of surfaces. For example, both of these surfaces may have a coating comprising the self-lubricating material discussed above. Alternatively, at least one of the surfaces may comprise a clip (as e.g. discussed above) comprising the self-lubricating material. By providing both surfaces with the self-lubricating material, acoustic noises and vibrations are suppressed particularly reliably.
According to a further example, the self-lubricating material is arranged at at least one perforated member. The perforation may include at least two through-holes formed in the member and preferably more than five through-holes or more than ten through-holes. A spatial distribution of the perforation (i.e. of its through-holes) may be regular to e.g. generate a spatially uniform lubrication. Yet, it may also be irregular, e.g. to locally increase lubrication.
A material of the perforated member may be different from the self-lubricating material. In particular, this material may be stiffer than the self-lubricating material and/or may not be elastically deformable when operating the wheel brake. In one example, the perforated member comprises and/or contacts at least one of the surfaces of the pair of surfaces.
The perforated member may act as a cover or shield for the self-lubricating material. Accordingly, it may limit or even prevent a direct contact of the self-lubricating material with a surface of the pair of surfaces that are to be lubricated. This may help to suppress mechanical abrasion of the self-lubricating material. On the other hand, contact forces exerted onto the perforated member may be transmitted by the letter to the self-lubricating material. This may promote a release of lubricant from the self-lubricating material. This lubricant may be released through the perforations of the perforated member, thus reaching the pair of surfaces to be lubricated. In sum, the perforated member may thus protect the self-lubricating material and/or enable a reliable and steady release of lubricant over a long operating life.
The perforated member may e.g. comprise a plastic material or a metal material, such as steel. This may provide a reliable protection and support of the self-lubricating material.
In one example, a clip according to any of the above embodiments may be provided, the clip comprising the perforated member. For example, the perforated member may form a sub-member or at least one layer of the clip. Accordingly, the perforated member may have a C-shape as well. The perforated member may form the stiffest member of (or within) the clip and/or the only member (or layer) that, on its own, is able to maintain a non-planar shape, such as a C-shape.
According to a further example, the self-lubricating material is arranged in between a first perforated member and a second perforated member, e.g. so as to be sandwiched in between them. In particular, the self-lubricating material may be provided at (and in particular in contact with) both of the first and second perforated member. The first and second perforated member may form outer surfaces of a clip and may be configured according to any embodiments disclosed herein. These outer surfaces may face away from one another. For example, each of said outer surfaces may face one of the first and second component. In particular, each of said outer surfaces may form one surface of a pair of surfaces that is to be lubricated.
In one example, the component assembly comprises a first pair of surfaces and a second pair of surfaces, the surfaces of each pair being configured as explained above with respect to the single pair of surfaces (i.e. being in contact with one another and moving relative to one another). At least one self-lubricating material may be provided that is configured to lubricate at least one and preferably both pairs of surfaces. In the latter case, the self-lubricating material may be arranged in between the first and second pair of surfaces. For example, the self-lubricating material may be sandwiched between perforated members as discussed above, in particular perforated members comprised by a clip as disclosed herein. The self-lubricating material may be configured to lubricate outer surfaces of both perforated members, with of the outer surface of each perforated member being comprised by one of the first and second pair of surfaces.
In further examples, one of the following is further provided:
Embodiments of the present disclosure are discussed in the following with reference to the attached schematic drawings. Throughout the figures, same or corresponding features may be marked with same reference signs.
The wheel brake assembly 10 is configured to press brake pads 26 (one of which is partially visible in
The brake caliper housing 12 comprises a receiving section 15. Only an outer wall of said receiving section 15 is visible in
The brake caliper housing 12 comprises a piston side 18 located at a first side face of the brake disc 16 and specifically at the same side face as the receiving section 15. Further, the brake caliper housing 12 comprises a finger side 20 located at the respective opposite side face of the brake disc 16 compared to the piston side 18. The finger side 20 comprises (merely as an example) two finger portions 21 according to known configurations.
The finger side 20 and the piston side 18 are connected to one another by a bridge section 22. The bridge section 22 overlaps with the outer circumferential surface of brake disc 16 or, put differently, axially spans across the brake disc 16 and/or extends from one of the side faces of said brake disc 16 to the other.
In a generally known manner, the brake piston received in the receiving section 15 and the inside of the finger portions 21 that face away from the viewer in
Just like the brake caliper housing 12, the brake pad carrier 14 comprises a piston side 18, a finger side 20 and a bridge section 22. Guiding grooves 24 of the brake pad carrier 14 are provided at an inner side of the bridge section 22 for slidingly receiving the two brake pads 26, one of said guiding grooves 24 being partially visible in
Each brake pad 26 comprises guiding projections 23, one of which is visible in
According to the configuration of
The guide pins 28 are secured to the brake caliper housing 12 by means of a screw connection. Specifically, fixing projections 31 are provided at each of a trailing side and a leading side of the brake caliper housing 12, said fixing projections 31 each comprising a non-visible through-hole. A guide pin 28 is aligned with each of said through holes to engage with a locknut 33 provided at an opposite side of the fixing projections 31. This way, the guide pins 28 are mechanically fixed to the fixing projections 31 and thus to the brake caliper housing 12.
For the purpose of illustration, the pad spring 25 is not shown in
The brake component assembly 34 comprises as a first component 36 the brake pad 26 and as a second component 38 of the brake pad carrier 14 and especially a guiding projection 23 comprised thereby. Similar to
Accordingly, the self-lubricating material 40 comprises a first surface 42 that is configured to contact a second surface 44 comprised by the guiding recess 24, the first surface 42 and the second surface 44 forming a pair of surfaces 46 that may contact one another. Another respective pair of surfaces 46 may be formed by the (in
The self-lubricating material 40 is elastically deformable by contact forces occurring during normal brake operation, e.g. during normal brake activation or brake release. In particular, the self-lubricating material 40 may be elastically deformable under the weight of any of the components 36, 38 of the brake component assembly 34. For example, the elastic deformation during brake operation may include a compressibility in at least one dimension of the self-lubricating material 40 (e.g. a thickness dimension) of at least 5%.
By coating those surfaces of the guiding projection 23 that may potentially contact the guiding recess 24 (or a non-illustrated optional pad spring 25) with the self-lubricating material 40, contact forces between these members may at least partially be dampened by an elastic deformation of the self-lubricating material 40. Also, these surfaces are self-lubricated to limit friction and thereby uncontrolled relative movements of the components 36, 38. As a result, the elastic deformation in combination with the self-lubrication help to limit vibrations and acoustic noises, especially during the above-discussed releasing stage according to
It is to be noted that the present disclosure is not limited to the brake component assembly 34 comprising the specific first and second components 36, 38 of
Further, in case of
In
A layer of self-lubricating material 40 is arranged in between and is thus sandwiched between the perforated members 50, 54. A lubricant that is exuded by said self-lubricating material 40 can thus be released through the through holes 52 towards the respective inner and outer external surfaces of the clip 48. This may e.g. occur when the self-lubricating material 40 is exposed to mechanical pressure and/or may occur steadily over time.
Merely as an example, the outer perforated member 54 may be thicker (i.e. have a larger material strength) than the inner perforated member 50.
Alternatively, these members may have a substantially similar thickness. A thickness of the self-lubricating material 40 may be lower than a thickness of any of the inner and outer perforated members 50, 54. For example, the outer perforated member 54 may have a thickness of 0.3 mm to 0.5 mm and/or the inner perforated member 50 may have a thickness of 0.2 mm to 0.3 mm. The layer of self-lubricating material 40 may have a thickness of 0.1 to 0.2 mm. Generally, any of the inner perforated member 50, outer perforated member 54 and self-lubricating material 40 may have a thickness of less than 1 mm and e.g. not more than 0.5 mm. A thickness dimension T is marked for the outer perforated member 54 in
Due to being arranged in between the perforated members 50, 54, the self-lubricating material 40 provides an elastic deformability of the overall clip 48. Specifically, the self-lubricating material 40 acts as an elastically deformable spacer that is arranged in between the perforated members 50, 54.
The brake component assembly 10 of
It may be beneficial to provide self-lubrication in between the clip 48 and the respective one of the brake pad 26 and brake pad carrier 14 at which the clip 48 is held. This is because small relative movements and in particular vibrations may still occur between these members. In the shown example, the clip 48 is connected to the brake pad 26 by a force fit resulting from an elastic deformation when pushing the clip 48 onto the guiding projection 23.
In
For the sake of completeness,
It is noted that a clip 48 as shown throughout the
It is also noted that the use of perforated members 50, 54 of e.g.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102023111503.0 | May 2023 | DE | national |
