Brake assembly and method for operating a brake assembly for a vehicle wheel

Abstract

The invention concerns a brake assembly for a vehicle wheel, the brake assembly comprising: a braked member that is coupable or coupled to the vehicle wheel for a joint rotation therewith about a rotational axis, the braked member having friction linings that are arranged at an axial distance from one another; and a braking unit that comprises an actuator and at least two displaceable members, the displaceable members being positioned in between the friction linings, wherein the actuator is configured move the displaceable members axially apart from one another, thereby bringing each displaceable member into contact with one of the friction linings of the braked member.

Claims

1. Brake assembly for a vehicle wheel, the brake assembly comprising: a braked member that is coupable or coupled to the vehicle wheel for a joint rotation therewith about a rotational axis, the braked member having friction linings that are arranged at an axial distance from one another; and a braking unit that comprises an actuator and at least two displaceable members, the displaceable members being positioned in between the friction linings, wherein the actuator is configured move the displaceable members axially apart from one another, thereby bringing each displaceable member into contact with one of the friction linings of the braked member.

2. Brake assembly according to claim 1, wherein the friction linings face each other.

3. Brake assembly according to claim 1, wherein the friction linings form at least part of opposite side faces of a space in which the displaceable members are at least partially received.

4. Brake assembly according to claim 3, wherein a brake dust collector is arranged within said space, in particular at a bottom face that extends in between the friction linings.

5. Brake assembly according to claim 1, wherein the displaceable members are movable apart from one another along an axis extending in parallel to the rotational axis.

6. Brake assembly according to claim 1, wherein the displaceable members each comprise a material that is harder and/or more wear resistant than a material comprised by the friction linings.

7. Brake assembly according to claim 1, wherein the friction linings are each comprised by brake disc portions of the braked member.

8. Brake assembly according to claim 7, wherein the brake disc portions extend in parallel to one another, in particular wherein the brake disc portions each extend orthogonally to the rotational axis of the braked member.

9. Brake assembly according to claim 1, wherein each of the displaceable members is displaceable relative to a housing (34) of the braking unit and relative to one another.

10. Brake assembly according to claim 1, wherein the actuator comprises one of an electric motor and a hydraulic chamber, each of which is configured to generate the force for moving both of the displaceable members.

11. Brake assembly according to claim 10, wherein at least part of the electric motor or hydraulic chamber are received in the space.

12. Brake assembly according to claim 1, wherein each of the displaceable members and the friction linings have a contact surface for contacting a respective other of the displaceable members and the friction linings, wherein at least one of the displaceable members and the friction linings has at least one recess in its contact surface.

13. Brake assembly according to claim 1, wherein at least one of the displaceable members comprises at least one cavity and/or comprises at least one recess in a portion facing away from a respectively adjacent friction lining.

14. Brake assembly according to claim 1, wherein the braked member comprises at least one underlayer (41) at which one of the friction linings is arranged.

15. Brake assembly according to claim 1, wherein at least one of the friction linings has a ring shape or comprises a number of ring segments.

16. Brake assembly according to claim 1, wherein a contact between the friction lining and displaceable members is formed only in a radially outer portion of the braked member.

17. Method of operating a brake assembly for a vehicle wheel, the brake assembly comprising: a braked member that is coupable or coupled to the vehicle wheel for a joint rotation therewith about a rotational axis, the braked member (22) having friction linings that are arranged at an axial distance from one another; and a braking unit that comprises at least two displaceable members, the displaceable members being positioned in between the friction linings, wherein the method comprises: moving the displaceable members axially apart from one another, thereby bringing each displaceable member into contact with one of the friction linings of the braked member.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0071] Embodiments of the invention are described below with respect to the attached schematic figures. Similar features may be marked with same reference signs throughout the figures.

[0072] FIG. 1 is a cross-sectional view of a braked member of a brake disc assembly according to a first embodiment of the invention.

[0073] FIG. 2 is a cross-sectional view of a braked member of a brake disc assembly according to a second embodiment of the invention.

[0074] FIG. 3 is a cross-sectional view of part of a braked member of a brake disc assembly according to a third embodiment of the invention.

[0075] FIG. 4 is a cross-sectional view of part of a braked member of a brake disc assembly according to a fourth embodiment of the invention.

[0076] FIG. 5-6 are a cross-sectional views of a braked member of a brake disc assembly according to a fifth and sixth embodiment of the invention, the braked member having a dust collector.

[0077] FIG. 7 is a cross-sectional view of a braked member of a brake disc assembly according to a seventh embodiment of the invention.

[0078] FIG. 8 is a cross-sectional view of a braked member of a brake disc assembly according to an eighth embodiment of the invention.

[0079] FIG. 9 is a cross-sectional view of a braked member of a brake disc assembly according to a ninth embodiment of the invention.

[0080] FIG. 10 is a cross-sectional view of a brake disc assembly according to a tenth embodiment of the invention.

[0081] FIG. 11 is a cross-sectional view of a brake disc assembly according to an eleventh embodiment of the invention.

[0082] FIGS. 12-13 are cross-sectional views of part of a braked member of a brake disc assembly according to a twelfth and thirteenth embodiment of the invention.

[0083] FIGS. 14-15 are cross-sectional views of part of a displaceable member of a brake disc assembly according to an fourteenth and fifteenth embodiment of the invention.

[0084] FIGS. 16-19 are cross-sectional views of part of a displaceable member of aa brake disc assembly according to a sixteenth to twentieth embodiment of the invention.

[0085] FIG. 20 is a cross-sectional view of a brake disc assembly according to a twenty-first embodiment of the invention.

[0086] FIG. 21 is a cross-sectional view of a brake disc assembly according to a twenty-second embodiment of the invention.

DETAILED DESCRIPTION

[0087] In FIG. 1, a cross-sectional view of a braked member 14 according to an embodiment of the invention is shown. The braked member 14 is part of a brake assembly 10 (see e.g. FIGS. 10 and 11) for braking a non-illustrated vehicle wheel whose position is indicated by reference sign 1. Accordingly, the vehicle wheel is positioned axially next to the braked member 14 and brake assembly 10. The vehicle wheel rotates about a rotational axis R. The cross-sectional plane of FIG. 1 (just like the cross-sectional planes of the further figures discussed below) extends vertically and includes the rotational axis R.

[0088] The braked member 14 jointly rotates with the vehicle wheel about the rotational axis R. The connection between the braked member 14 and the vehicle wheel may be formed according to configurations of known disc brakes, e.g. by connecting both to a wheel hub and/or to a common axle component.

[0089] The braked member 14 has two brake disc portions 20. In the shown example, these are provided and comprised by distinct brake disc members. The brake disc members are fixed to an axially extending connecting portion 22. Merely as an example, the connecting portion 22 is hollow and axially elongated with a C-shaped cross-section. The connecting portion 22 may also be referred to as a hub portion. It may receive and be mounted at an axle component.

[0090] The brake disc portions 20 each extend orthogonally and concentrically to the rotational axis R. They have a circular shape and may generally be configured similar to known brake discs, e.g. in terms of material and structure. The brake disc portions 20 may each comprise cavities 21 not each of which is marked with an own reference sign. The cavities 21 may extend locally, e.g. as compact hollow portions, or may extend circumferentially as rings. They may contribute to weight savings. Alternatively, the cavities 21 may define ventilations channels that are fluidically connected to the surroundings.

[0091] Each brake disc portion 20 has an axially outer face 24 and an axially inner face 26. The inner faces 26 of the brake disc portions 20 face inwards and face one another. The outer faces 24 face outwards and away from the respective inner face 26 of each brake disc portion 20.

[0092] At each inner face 26 a friction lining 27 is arranged. The friction linings 27 are each formed as circular discs having a flat ring-shape and extending concentrically about the rotational axis R. The friction linings 27 thus form continuous and closed rings with planar contact surfaces 29 facing one another (i.e., facing axially inwards). As indicated by arrows, the contact surfaces 29 are each to be contacted by a displaceable member 18 of a braking unit 16 discussed e.g. with respect to FIGS. 10 and 11 below. An axial distance x between the contact surfaces 27 and thus an axial width x of a space 28 confined by the brake disc portions 20 is marked in FIG. 1.

[0093] In the example of FIG. 1, the outer faces 24 are not used for generating braking forces, i.e. do not comprise any friction lining 27. An embodiment where the outer contact faces 24 are also used for generating brake forces is described below with respect to FIG. 19.

[0094] The inner faces 26 (and the friction linings 27 attached thereto) confine the space 28 in between them. Said space 28 forms a circumferentially extending slot or ring within the braked member 14. Its axial side faces are formed by the friction linings 27. A bottom face 30 of the space 28 is provided by the connecting portion 22.

[0095] In the following, some further embodiments of braked members 14 are discussed. The embodiment of FIG. 2 differs from that of FIG. 1 substantially only with respect to the connecting portion 22. It is formed as a cylindric tube-like member having a substantially constant cross-section and e.g. configured to receive a non-illustrated axle component.

[0096] In FIG. 3, the braked member 14 is comparable to FIG. 2 in particular with respect to the connecting portion 22. For illustrative reasons, only the radial upper halves of the brake disc portions 20 are shown. In this embodiment, elongated recesses 23 (not each of which is marked by an own reference sign) extend from the outer faces 24 axially inward. These recesses 23 help to save weight and also increase a surface area for dissipating heat which the braked member 14 is exposed to when braking.

[0097] In FIG. 3, the braked member 14 is comparable to FIG. 1 in particular with respect to the connecting portion 22. Again, the braked member 14 is provided with elongated recesses 23 (not each of which is marked by an own reference sign) that are positioned similarly and provide same effects as in the embodiment of FIG. 3.

[0098] FIG. 5 and FIG. 6 (showing only a radial upper half of the brake disc portions 20) depict optional developments of the embodiments of FIGS. 1 and 2. In both cases, a brake dust collector 32 is arranged at and/or forms at least a section of the bottom face 30 of the space 28. The brake dust collector 32 is a ring-shaped member or layer that is arranged at an outer circumferential surface of the connecting portion 22. It comprises an adhesive to which brake dust sticks instead of being emitted into the environment.

[0099] FIGS. 7 and 8 show braked members 14 whose brake disc portions 20 have an increased radially inner stiffness. Specifically, radially inner base portions 31 that are adjacent to (e.g. merged with or attached to) the connecting portion 22 are marked by an increased axial width. In a radial outer direction, this axial width decreases. In the depicted example, it decreases continuously and the radially upper and lower halves of each brake disc portion 20 thus have a triangular cross-sectional shape. This way, the base portions 31 which experience increased bending stresses are sufficiently stiff, while radially outer sections of the brake disc portions 20 which are less mechanically stressed are lighter.

[0100] FIG. 8 additionally shows an vibration-dampening underlayer 41 that is optionally placed between each friction lining 27 and inner face 26 of the brake disc portions 20.

[0101] FIG. 9 shows as another optional feature of the displaceable member 14 of FIG. 7 a brake dust collector 32 similar to the embodiments of FIGS. 5 and 6.

[0102] FIGS. 10 and 11 show complete brake assemblies 10 comprising braked members 14 according to the embodiment of FIG. 7. The brake assemblies 10 also comprise a braking unit 16. The braking unit 16 at least partially extends into the space 28. In particular, it comprises displaceable members 18 that are preferably fully received within the space 28 and an actuator 12 for displacing the displaceable members 18.

[0103] The displaceable members 18 extend substantially in parallel to the inner friction linings 27 and/or the brake disc portions 20. At a face thereof facing the respectively adjacent friction lining 27, the displaceable members 18 each comprise a material that is different from and e.g. harder that the friction material of the friction lining 27. For example, said material may be a metallic material, such as cast iron. This increases the heat dissipation potential of the displaceable members 18. More precisely, a contact surface 29 of the left displaceable member 18 in FIG. 10 is directly adjacent and opposite to the left friction lining 27, whereas the contact surface 29 of the right displaceable member 18 in FIG. 10 is directly adjacent and opposite to the friction lining 27.

[0104] The displaceable members 18 are arranged at opposite sides of a housing 34 of the braking unit 16. The housing 34 may form or be formed by a brake caliper. Specifically, the displaceable members 18 are arranged so that their contact surfaces 29 face away from one another and face a respectively adjacent friction lining 27. Also, the displaceable members 18 are axially spaced apart from one another when viewed along the rotational axis R.

[0105] FIG. 10 shows an activated state of the brake assembly 10. Therefore, contrary to the inactive state, no axial gap exists between the contact surfaces 29 of the displaceable members 18 and each friction lining 27, so that theses contact one another to generate friction forces. When activated from an inactive state, the displaceable members 18 move axially apart from one another as indicated by arrows in FIG. 1. An axial distance between the displaceable members 18 is thus increased and each contact surface 29 is brought into contact with the respectively opposite friction lining 27. This generates frictional forces between the contact surfaces 29 and friction linings 27 which brake a rotation of the braked member 14. When deactivated, the displaceable members 18 are lifted off of a respectively adjacent friction lining 27 while reducing an axial distance between the displaceable members 18.

[0106] In FIG. 10, the braking unit 16 and specifically its housing 34 comprises a hydraulic chamber 36. The hydraulic chamber 36 is part of or resembles the actuator 12. According to a generally known configuration and as indicated by an arrow, a hydraulic pressure can be built up in said hydraulic chamber 36 for moving the displaceable members 18, thus activating the brake. In more detail, each displaceable member 18 is connected to a piston 38 that is slidingly received in the housing 34 and reaches into the hydraulic chamber 36. By increasing the pressure inside the hydraulic chamber 36, the pistons 38 are axially moved apart from one another and pushed outwards. When releasing the pressure in the hydraulic chamber 36, the pistons 38 and thus the displaceable members 18 axially retract, so that the contact surfaces 29 are lifted off and away from the respectively opposite friction lining 26. This retraction movement may be supported by known elastic seals which act on the pistons 38.

[0107] It is to be noted that the pistons 38 as well as at least part of the hydraulic chamber 36 as well as part of the housing 34 are received within the space 28.

[0108] Further, any of these members as well as the displaceable members 18 (and generally the braking unit 16 as a whole) may have a defined extension in the circumferential direction and/or orthogonally to the image plane so that a sufficiently large areal contact between the displaceable members 18 and the friction linings 27 can be formed. Preferably, this circumferential extension is limited to below of 180° or below of 135° to increase compactness and to save weight.

[0109] FIG. 11 shows an embodiment similar to FIG. 10, but having a different actuator 12. This actuator 12 comprises an electric motor 51. For axially moving the displaceable members 18 to and away from the friction linings 27, the electric motor 51 is connected to each displaceable member 18 by an optional gear stage or spindle mechanism 52.

[0110] FIGS. 12 and 13 each show one upper half of a brake disc portion 20 comprised by the braked member 14 according to a further embodiment. In these examples, the contact surfaces 29 of the friction lining 27 comprise a number of recesses 53. These may be formed as circumferentially extending rings or ring segments. FIGS. 12 and 13 differ in terms of the number, dimensioning and positioning of said recesses 53, but are both non-limiting examples.

[0111] FIGS. 14 and 15 show displaceable members 18 in a state of contacting an adjacent brake lining 27. The displaceable members 18 have recesses 53 in their contact surfaces 29, with FIGS. 14 and 15 showing different and non-limiting numbers, dimensions and positions of said recesses 53.

[0112] The embodiments of FIGS. 12, 13 and 14, 15 may be combined, i.e. both of the brake linings 27 and displaceable members 18 may have recesses 53 in their respective contact surfaces 29. The recesses 53 in any of the brake linings 27 and displaceable members 29 may help to limit contact forces and/or vibrations resulting therefrom, thus reducing brake noises. Also, they may help to guide brake dust away from a contact area and e.g. radially inwards towards an optional brake dust collector 32.

[0113] FIGS. 16-19 show exemplary configurations of displaceable members 18 having recesses 55. The recesses 55 are positioned outside of a contact surface 29 the displaceable members 18, said contact surface 29 facing an adjacent friction lining 27.

[0114] In FIGS. 16 and 17, the recesses 55 are positioned in a rear face 56 opposite the contact surface 29. The recesses 55 in FIG. 16 have identical dimensions, whereas these dimensions vary in FIG. 17. In FIG. 18, recesses 55 are (additionally or alternatively) positioned in circumferential faces 58 of the depicted displaceable members 18, e.g. at a radially upper or lower face. The recesses 55 help to save weight and to increase heat dissipation.

[0115] FIG. 20 shows a brake assembly similar to FIG. 10. In this case, a contact between the friction linings 27 and displaceable members 18 is only generated at a radial distance to or, in other words, radial offset from the connecting portion 22 (and/or base portion 31). Put differently, it is produced only in a radially outer portion or tip portion of the brake disc portions 20.

[0116] This increases the effective braking radius. In FIG. 20, this is achieved by positioning the friction linings 27 and brake unit 16 in said radially outer portion. As depicted, the friction linings 27 may thus not extend along the complete inner faces 26 of the brake disc portions 20, but may only be provided in the radially outer portion. This saves costs and weight.

[0117] FIG. 21 shows a brake assembly 10 according to another embodiment. In this case, the outer contact faces 24 of the brake disc portions 20 are each contacted by a displaceable member 18 as well to generate additional brake forces.

[0118] Accordingly, the braking unit 16 also comprises two outer displaceable members 18 each being adjacent to one of the outer faces 24. At said outer faces 24, a friction lining 27 is arranged similar to the inner faces 26. In the shown example, these displaceable members 18 are configured similarly to the inner displaceable members 18 that are arranged in the circumferential space 28 of the braked member 14.

[0119] The housing 34 of the brake unit 16 has axially outer portions 35 that face the outer faces 24. The axially outer portions 35 are axially positioned further outwards compared to the outer faces 24. Each axially outer portion 35 receives a piston 38 so that a displaceable member 18 arranged at the respective axially outer portion 35 can be displaced in a similar manner as described above e.g. with respect to FIGS. 10 and 11. For doing so, the hydraulic chamber 36 also extends into the axially outer portions 35. The inner displaceable members 18 are generally configured and displaced similar to the embodiments discussed above.

[0120] In order to generate brake forces, a hydraulic pressure within the hydraulic chamber 36 is built up, upon which all four displaceable members 18 are displaced simultaneously towards their respectively opposite friction lining 27.

[0121] Thus, one single actuator 12 comprising said hydraulic chamber 36 suffices to activate the braking function.