Abstract
A brake assembly includes a brake disc rotatable about a rotational axis, a service brake assembly with a service brake pad and configured to apply a service brake force on a radial surface side of the brake disc, wherein the service brake pad is axially moveable with respect to the rotational axis and has a service brake braking surface facing the radial surface side of the brake disc to apply the service brake force, a park brake assembly with a park brake pad and configured to apply a park brake force on the or another radial surface side of the brake disc, wherein the park brake pad is axially moveable with respect to the rotational axis and has a park brake braking surface facing the or the other radial surface side of the brake disc to apply the park brake force. The park brake braking surface of the park brake pad is arranged at a radial park brake pad distance with respect to the rotational axis different from a radial service brake pad distance of the service brake braking surface of the service brake pad.
Claims
1.-15. (canceled)
16. A brake assembly for a vehicle, comprising: a brake disc rotatable about a rotational axis; at least one service brake assembly comprising at least one service brake pad and configured to apply a service brake force on a radial surface side of the brake disc, wherein the at least one service brake pad is axially moveable with respect to the rotational axis and comprises a service brake braking surface facing the radial surface side of the brake disc to apply the service brake force; and at least one park brake assembly comprising at least one park brake pad and configured to apply a park brake force on the or another radial surface side of the brake disc, wherein the at least one park brake pad is axially moveable with respect to the rotational axis and comprises a park brake braking surface facing the or the other radial surface side of the brake disc to apply the park brake force, wherein the park brake braking surface of the at least one park brake pad is arranged at a radial park brake pad distance with respect to the rotational axis different from a radial service brake pad distance of the service brake braking surface of the at least one service brake pad.
17. The brake assembly according to claim 16, wherein the radial park brake pad distance is more than the radial service brake pad distance relative to the rotational axis.
18. The brake assembly according to claim 16, wherein the radial park brake pad distance is less than the radial service brake pad distance relative to the rotational axis.
19. The brake assembly according to claim 16, wherein the brake disc comprises a park brake brake disc portion facing the park brake braking surface of the at least one park brake pad in at least one rotational position of the brake disc, and a service brake brake disc portion facing the service brake braking surface of the at least one service brake pad in the at least one or in at least one other rotational position of the brake disc, and a frictional pairing of the park brake brake disc portion and the park brake braking surface of the at least one park brake pad is configured to provide a friction coefficient different from the friction coefficient of a frictional pairing of the service brake brake disc portion and the service brake braking surface of the at least one service brake pad.
20. The brake assembly according to claim 16, wherein a friction coefficient of a frictional pairing of the park brake braking surface of the at least one park brake pad and the brake disc is at least 0.55.
21. The brake assembly according to claim 16, wherein the at least one park brake pad is arranged to extend in a cooling channel of the brake disc formed between two outer radial surface sides of the brake disc from an outer circumference or an inner circumference of the brake disc.
22. The brake assembly according to claim 21, further comprising: the park brake assembly comprising the at least one park brake pad arranged to extend in a cooling channel of the brake disc; and another park brake assembly.
23. The brake assembly according to claim 16, wherein the park brake braking surface of the at least one park brake pad comprises a park brake pad form-fit portion, and the brake disc comprises a corresponding brake disc form-fit portion at the radial park brake pad distance.
24. The brake assembly according to claim 23, wherein the park brake assembly comprises a park brake pad carrier assembly carrying the at least one park brake pad and configured to move the at least one park brake pad toward the brake disc in the axial direction or to allow a respective movement of the at least one park brake pad, and the park brake assembly further comprises at least one local displacement member arranged between the at least one park brake pad and the park brake pad carrier assembly configured to allow a relative displacement of the at least one park brake pad with respect to the park brake pad carrier assembly in a direction within the braking surface plane.
25. The brake assembly according to claim 24, wherein the at least one local displacement member is a bearing member arranged on a surface side of the at least one park brake pad opposed to the braking surface of the at least one park brake pad.
26. The brake assembly according to claim 24, wherein the at least one local displacement member is a spring member arranged on a lateral surface side of the at least one park brake pad substantially in parallel to the axial direction and perpendicular to a projection of the rotational movement of the brake disc in parallel to the at least one park brake pad with a respective spring force acting in the direction of the projection of the rotational movement of the brake disc in parallel to the at least one park brake pad.
27. The brake assembly according to claim 24, wherein the park brake assembly comprises an overload clutch arranged on the surface side of the at least one park brake pad opposed to the braking surface of the at least one park brake pad.
28. The brake assembly according to claim 24, wherein the park brake assembly comprises an axial spring member arranged on the surface side of the at least one park brake pad opposed to the braking surface of the at least one park brake pad with a predetermined axial spring force acting in the axial direction.
29. A method of operating a brake assembly having a brake disc rotatable about a rotational axis; at least one service brake assembly comprising at least one service brake pad and configured to apply a service brake force on a radial surface side of the brake disc, wherein the at least one service brake pad is axially moveable with respect to the rotational axis and comprises a service brake braking surface facing the radial surface side of the brake disc to apply the service brake force; and at least one park brake assembly comprising at least one park brake pad and configured to apply a park brake force on the or another radial surface side of the brake disc, wherein the at least one park brake pad is axially moveable with respect to the rotational axis and comprises a park brake braking surface facing the or the other radial surface side of the brake disc to apply the park brake force, wherein the park brake braking surface of the at least one park brake pad is arranged at a radial park brake pad distance with respect to the rotational axis different from a radial service brake pad distance of the service brake braking surface of the at least one service brake pad, wherein the at least one park brake pad is arranged to extend in a cooling channel of the brake disc formed between two outer radial surface sides of the brake disc from an outer circumference or an inner circumference of the brake disc, the method comprising the steps of: applying the at least one park brake pad to apply the park brake force on the radial surface side of the brake disc of the brake assembly, wherein the at least one park brake pad is only activated to apply the park brake force in a standstill state of a vehicle.
30. A vehicle, comprising: a brake assembly according to claim 16; wherein the vehicle is configured as a commercial vehicle, a truck, a trailer, a bus and/or as a combination of a towing vehicle and a trailer, and/or wherein the vehicle comprises a pure electric, a hybrid or a conventional powertrain.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] FIG. 1 is a lateral view of a brake assembly according to a first exemplary embodiment of a brake assembly;
[0052] FIG. 2 is a lateral view of a brake assembly according to a second exemplary embodiment of a brake assembly;
[0053] FIG. 3 is a lateral view of a brake assembly according to a third exemplary embodiment of a brake assembly;
[0054] FIG. 4 is a cross-sectional view of a section of a park brake assembly applicable to the brake assembly according to FIG. 3;
[0055] FIG. 5 is a lateral view of a brake disc according to an exemplary embodiment;
[0056] FIG. 6 is a cross-sectional view of a section of the brake disc according to FIG. 5;
[0057] FIG. 7 is a lateral view of a brake assembly according to a fourth exemplary embodiment of a brake assembly;
[0058] FIG. 8 is a cross-sectional view of a section of a park brake assembly applicable to the brake assembly according to FIG. 7;
[0059] FIG. 9 is a cross-sectional view of a section of a brake assembly according to a fifth exemplary embodiment of a brake assembly;
[0060] FIG. 10 is a cross-sectional view of a section of the brake assembly according to a sixth exemplary embodiment of a brake assembly;
[0061] FIG. 11 is a cross-sectional top view of a section of the brake assembly according to FIG. 3;
[0062] FIGS. 12a to 12e are schemes of operation for the engagement of a park brake pad form-fit portion of a park brake pad into a brake disc form-fit portion of a brake disc according to FIGS. 3 and 11 in a comparably advantageous scenario;
[0063] FIGS. 13a to 13e are schemes of operation for the engagement of a park brake pad form-fit portion of a park brake pad into a brake disc form-fit portion of a brake disc according to FIGS. 3 and 11 in a comparably disadvantageous scenario;
[0064] FIGS. 14a to 14d are schemes of operation for the engagement of a park brake pad form-fit portion of a park brake pad into a brake disc form-fit portion of a brake disc using a clutch; and
[0065] FIGS. 15a to 15c are schemes of operation for the engagement of a park brake pad form-fit portion of a park brake pad into a brake disc form-fit portion of a brake disc using an axial spring member.
DETAILED DESCRIPTION OF THE DRAWINGS
[0066] FIG. 1 shows a lateral view of a brake assembly 1 according to a first exemplary embodiment. The brake assembly 1 comprises a brake disc 10 rotatable about a rotational axis R. Here, the lateral view corresponds to a view in the direction of the rotational axis R on a radial surface side of the brake disc with respect to the rotational axis R. The brake assembly 1 further comprises a park brake assembly 20 comprising a park brake caliper 21 as a park brake pad carrier assembly to carry a park brake pad 22. In the exemplary embodiment, the park brake caliper 21 is a floating caliper further carrying another park brake pad (not shown) on an opposed radial surface side of the brake disc 10. However, in other embodiments, the park brake caliper 21 may be a fixed caliper or may be a park brake pad carrier assembly for only one or more than two park brake pads. The brake assembly 1 also comprises a service brake assembly 30 comprising a service brake caliper 31 as a service brake pad carrier assembly to carry a service brake pad 32. Similar to the park brake caliper 21, the service brake caliper 31 is a floating caliper with another service brake pad arranged on the opposed radial surface side of the brake disc 10 (not shown) in the exemplary embodiment. In alternative embodiments, the service brake caliper may also be a fixed caliper or may be a service brake pad carrier assembly for only one or more than two service brake pads. Each of the park brake caliper 21 and service brake caliper 31 comprises or may be operatively connected to an actuator mechanism to move the respective park brake pad 22 or the service brake pad 32, respectively, each of which being axially movably supported in the park brake caliper 21 or service brake caliper 31, respectively, in the axial direction with respect to the rotational axis R toward the brake disc 10 to apply a clamping force upon contact.
[0067] In the exemplary embodiment, the park brake pad 22 is arranged in a radial park brake pad distance rPB, which is the distance of the rotational axis R to the mid-height of the park brake pad 22 in the radial direction. Further, the service brake pad 32 is arranged in a radial service brake pad distance rSB, which is the distance of the rotational axis R to the mid-height of the service brake pad 32 in the radial direction. Here, the radial park brake pad distance rPB is more than the radial service brake pad distance rSB. Specifically, the park brake pad 22 and the service brake pad 32 are configured and arranged such that each of the park brake pad 22 and the service brake pad 32 act on different circumferential brake disc portions without overlap. In other words, the park brake pad 22 and the service brake pad 32 are configured and arranged such that an outer radial distance of the service brake pad 32 is less than an inner radial distance of the park brake pad 22. In alternative embodiments, the park brake pad 22 and the service brake pad 32 may provide some overlap in terms of being configured and arranged to partially act on the same circumferential brake disc portion.
[0068] Since the radial park brake pad distance rPB is more than the radial service brake pad distance rSB, the radial park brake pad distance rPB as a lever or lever arm vector with respect to torque with respect to the rotational axis R requires a smaller clamping force for the park brake pad 22 to achieve the same braking torque with respect to the service brake pad 32 arranged in a radial service brake pad distance rSB as a lever with respect to a torque around the rotational axis R less than the radial park brake pad distance. In the exemplary embodiment, but not necessarily, the brake disc 10 comprises a park brake brake disc portion 10a as an outer annular portion extending circumferentially around the rotational axis R for a frictional pairing with the park brake pad 22 and a service brake brake disc portion 10b as an inner annular portion extending circumferentially around the rotational axis R for a frictional pairing with the service brake pad 32, wherein the friction coefficient of the service brake brake disc portion 10b is higher than the friction coefficient of the park brake brake portion 10a to at least partially compensate the smaller lever due to the radial service brake pad distance rSB to reduce the required clamping force. However, in alternative embodiments, the friction coefficient of the park brake brake disc portion 10a is higher than the friction coefficient of the service brake brake portion 10b to further decrease the required clamping force.
[0069] FIG. 2 shows a lateral view of a brake assembly 1 according to a second exemplary embodiment. The reference signs denote the same features as in the first embodiment but indicated by . Accordingly, a detailed description of the common features is omitted. The second embodiment differs from the first embodiment in the arrangement and configuration of the park brake pad 22 and the service brake pad 32 and the respective park brake brake disc portion 10a and service brake brake disc portion 10b. here, the park brake pad is arranged in a radial park brake pad distance rPB less than the radial service brake pad distance rSB. Accordingly, the clamping force for the park brake pad 22 to achieve the same braking torque than the service brake pad 32 needs to be higher. Similar to the first embodiment, the park brake brake disc portion 10a as inner annular portion provides a higher friction coefficient than the service brake brake disc portion 10b as outer annular ring portion to at least partially compensate such effect.
[0070] FIG. 3 shows a lateral view of a brake assembly 1 according to a third exemplary embodiment. The reference signs denote the same features as in the first embodiment but indicated by . Accordingly, a detailed description of the common features is omitted. The third embodiment differs from the first embodiment in that the brake disc 10 comprises a brake disc form-fit portion 11 as an annular portion extending circumferentially around the rotational axis R to provide a form-fit connection with a corresponding park brake pad form-fit portion 22a (FIG. 4) to further support the previously described friction-based park braking function. In the exemplary embodiment, the brake disc form-fit portion 11 is formed by serrations with equally distanced teeth in the circumferential direction.
[0071] FIG. 4 shows a cross-sectional view of a section of a park brake assembly applicable to the brake assembly 1 according to FIG. 3. The park brake assembly comprises a park brake caliper 21 accommodating an actuator 24 movable in the axial direction with respect to the rotational axis R to move the park brake pads 22, each of which is arranged on an opposed radial surface side of the brake disc 10 toward the brake disc 10. The one park brake pad 22 arranged between the one radial surface side of the brake disc 10 and the actuator 24 is directly actuated by the actuator 24, whereas the other park brake pad 22 is indirectly actuated due to the park brake caliper 21 configured as floating caliper. In the exemplary embodiment, a transfer member 23 is arranged on each surface side of the respective park brake pads 22 facing away from the brake disc 10 in the axial direction. In the exemplary embodiment, the transfer members 23 represent the bearing members 25 or rollers, respectively, which will be described in more detail with respect to FIG. 9. However, in other embodiments, the transfer members 23 may comprise other functionalities to actuate, support and/or guide the park brake pads 22. Each of the park brake pads 22 comprises the park brake pad form-fit portion 22a, each of which facing toward a corresponding brake disc form-fit portion 11 on each outer radial surface side of the brake disc 10. The brake disc 10 further comprises a cooling channel 12 which is formed by a distance between two outer portions of the brake disc 10 extending radially connected by a plurality of connecting members 13. In the exemplary embodiment, the connecting members 13 form an integral part of the brake disc 10.
[0072] FIG. 5 shows a lateral view of brake disc 10 according to an exemplary embodiment. In this variant, the brake disc 10 comprises several mounting holes 14 to mount a brake disc form-fit portion as separate annular member on the brake disc 10.
[0073] FIG. 6 shows a cross-sectional view of a section of the brake disc 10 according to FIG. 5. The reference signs denote the same features as in FIG. 4 but indicated by . Accordingly, a detailed description of the common features is omitted. In accordance with the description of FIG. 5, the shown embodiment of the brake disc 10 in FIG. 6 differs from the embodiment of the brake disc 10 in FIG. 4 in that the brake disc form-fit portion 11 is mounted on the brake disc 10, here, by mounting members 15 such as screws, bolts, rivets or the like.
[0074] FIG. 7 shows a lateral view of a brake assembly 1 according to a fourth exemplary embodiment. The reference signs denote the same features as in the second embodiment but indicated by . Accordingly, a detailed description of the common features is omitted. The fourth embodiment differs from the first embodiment in that the brake disc 10 comprises a brake disc form-fit portion 11 as an annular portion extending circumferentially around the rotational axis R to provide a form-fit connection with a corresponding park brake pad form-fit portion 22a (FIG. 8) to further support the previously described friction-based park braking function. In the exemplary embodiment, the brake disc form-fit portion 11 is formed by serrations with equally distanced teeth in the circumferential direction. While the brake disc form-fit portion 11 in FIG. 3 is provided as an outer annular portion, the brake disc form-fit portion 11 in FIG. 7 is an inner annular portion to comply with the smaller radial park brake pad distance rPB.
[0075] FIG. 8 shows a cross-sectional view of a section of a park brake assembly applicable to the brake assembly 1 according to FIG. 7. The park brake assembly in FIG. 8 differs from the park brake assembly shown in FIG. 4 by the frictional pairing and the form-fit pairing of the brake disc 10 and the park brake pad 22 being provided at an inner annular portion of the brake disc 10.
[0076] FIG. 9 shows a cross-sectional view of a section of a brake assembly according to a fifth exemplary embodiment of a brake assembly. Here, the park brake bad 22 partially extends in the cooling channel from an outer circumference of the brake disc 10. The park brake pad 22 is axially movable with respect to the rotational axis to contact an inner radial surface side of the cooling channel, which, in the exemplary embodiment further comprises a brake disc form-fit portion 11 corresponding to a park brake pad form-fit portion (not shown). However, in other embodiments, the park brake pad 22 and the brake disc 10 mayonly provide a frictional pairing. The park brake pad 22 is moveable to only one inner radial surface side of the brake disc 10 for applying a clamping force. However, in other embodiments, the park brake pad 22 may also be actuated to apply a clamping force on either the one or the other inner radial surface side of the brake disc 10. In further embodiments, the park brake pad 22 may comprise two park brake braking surfaces to be spread apart in the axial direction to simultaneously apply a clamping force on both inner radial surface sides of the brake disc 10, which may also be accomplished by two separate park brake pads 22 both extending in the cooling channel.
[0077] FIG. 10 shows a cross-sectional view of a section of the brake assembly according to a sixth exemplary embodiment. The reference signs denote the same features as in FIG. 9 but indicated by . Accordingly, a detailed description of the common features is omitted. The sixth embodiment differs from the fifth embodiment in that the park brake pad 22 extends in the cooling channel from an inner circumference of the brake disc 10. The same principles as described above for the fifth embodiment also apply for the sixth embodiment with respect to actuation of the park brake pad 22 to apply a clamping force on the brake disc 10.
[0078] FIG. 11 shows a cross-sectional top view of a section of the brake assembly 1 according to FIG. 3. Since the park brake pad form-fit portion 22a (FIG. 3) of the park brake pad 22 may not be precisely aligned with the brake disc form-fit portion 11 (FIG. 3), the park brake caliper 21 comprises bearing members 25 disposed on a surface side of the park brake pad 22 facing away from the radial surface sides of the brake disc 10 and supported by the park brake caliper 21. Further, the park brake caliper 21 comprises a spring member 26 on each lateral side of each of the park brake pads 22 to provide a resilient connection of the park brake pads 22 with the park brake caliper 21 in a projection direction of the rotational movement of the brake disc 10 perpendicular to the rotational axis R and perpendicular to the radial direction with respect to the rotational axis R. The spring members 26 are each partially accommodated in a recess of the park brake caliper 21, the open end of which also partially functions as an abutment for the respective park brake pad 22 to limit a moving ability in the projection direction. The spring members 26 are configured and arranged to center the respective park brake pad 22 in the middle position within the park brake caliper 21 in the projection direction, when the parking brake pad 22 is not actuated, so to provide the park brake pad form-fit portion with sufficient available travel to align with the brake disc form-fit portion.
[0079] FIGS. 12a to 12e show schemes of operation for the engagement of a park brake pad form-fit portion 22a of the park brake pad 22 into a brake disc form-fit portion 11 of a brake disc 10 according to FIGS. 3 and 11 in a comparably advantageous scenario. In principle, the spring members 26 and bearing members 25 allow the parking brake pads 22 to get substantially immediately in contact with the brake disc 10 when the park brake assembly is actuated accordingly. However, for a transfer of the clamping forces, the brake disc 10 may slightly have to turn to overcome the clearance between the park brake pads 22 and the park brake caliper 21, which results in an unbraked travel. In an advantageous scenario, the park brake pad 22 according to FIG. 12a without being actuated is centered by the spring members 26. Upon actuating, as indicated by the arrow directed in the axial direction, the park brake pad 22 is moved toward the brake disc 10 in the axial direction with respect to the rotational axis R (FIG. 12b). FIG. 12c shows the initial contact of the park brake pad form-fit portion with the brake disc form-fit portion. The park brake pad form-fit portion fully engages the brake disc form-fit portion while the brake disc 10 further rotates, which causes the park brake pad 22 to move in the projection direction of the rotational movement, indicated by the vertical arrow (FIG. 12d). Accordingly, the spring member 26 upstream in the projection direction is extended while the spring member 26 downstream in the projection direction is compressed. The unbraked travel of the brake disc 10 stops when the park brake pad 22 abuts at the park brake caliper 21 or when the clearance between the park brake pad 22 and the park brake caliper 21 in the projection direction is closed, respectively.
[0080] FIGS. 13a to 13e show schemes of operation for the engagement of a park brake pad form-fit portion of a park brake pad 22 into a brake disc form-fit portion of a brake disc according to FIGS. 3 and 11 in a comparably disadvantageous scenario. FIGS. 13a and 13b substantially correspond to FIGS. 12a and 12b, a description of which is therefore omitted. As per FIG. 13c, the initial contact of the park brake pad 22 with the brake disc 10 urges the park brake pad form-fit portion to engage the brake disc form-fit portion at a serration upstream of the brake disc form-fit portion with respect to the rotation direction or projection direction, respectively. Accordingly, the park brake pad 22 is first moved slightly upstream before it is moved in the final abutment with the park brake caliper 21, as illustrated by FIGS. 13d and 13e. Consequently, the unbraked travel of the brake disc 10 is longer than in the more advantageous scenario. Accordingly, the clearance between the park brake pad 22 and the park brake caliper 21 is configured to keep the unbraked travel of the brake disc 10 at a predetermined maximum for such unbraked in any event.
[0081] FIGS. 14a to 14d show schemes of operation for the engagement of a park brake pad form-fit portion of a park brake pad into a brake disc form-fit portion of a brake disc 10 using an overload clutch 27. The configuration of the respective park brake assembly corresponds to the ones of FIGS. 12a-e and 13a-e besides the additional overload clutch 27. FIG. 14a illustrates a position of the park brake pad 22 as per FIG. 12e or FIG. 13e, respectively. If the braking torque becomes too high, i.e. exceeds a predetermined torque threshold, the overload clutch 27 allows the park brake pad 22 to move away from the brake disc 10, as shown in FIG. 14b. According to FIG. 14c, with the braking torque being released from the park brake pad 22, the park brake pad 22 is moved back toward the brake disc 10 and returns to the clamping state as per FIG. 14d.
[0082] FIGS. 15a to 15c show schemes of operation for the engagement of a park brake pad form-fit portion of a park brake pad into a brake disc form-fit portion of a brake disc 10 using an axial spring member 28. The axial spring member is arranged between the actuator 24 and an axial spring member support 29 to preload the actuator 24 in the axial direction with respect to the rotational axis R. In the event that the park brake pad form-fit portion does not precisely align with the brake disc form-fit portion upon actuation of the park brake pad 22 to engage the brake disc 10, the brake disc 10 slides relative to the park brake pad to the next section of the park brake pad form-fit portion, e.g. the next serration section, and the park brake pad form-fit portion may snap into the brake disc form-fit portion accordingly to transfer the clamping force. The axial spring member 28 thereby allows the same overload clutch function as the overload clutch 27 as previously described.
[0083] The invention has been described with respect to exemplary embodiments. However, the invention is not limited to the exemplary embodiments.
LIST OF REFERENCE SIGNS
[0084] 1, 11, 1, 1 brake assembly [0085] 10, 10, . . . , 10 brake disc [0086] 10a, 10a park brake brake disc portion [0087] 10b, 10b service brake brake disc portion [0088] 11, . . . , 11 brake disc form-fit portion [0089] 12, 12, 12 cooling channel [0090] 13, . . . , 13 connecting member [0091] 14 mounting hole [0092] 15 mounting member [0093] 20, 20, 20, 20 park brake assembly [0094] 21, 21, 21, 21, 21 park brake caliper (park brake pad carrier assembly) [0095] 22, 22, 22, 22, . . . , 22 park brake pad [0096] 22a, 22a park brake pad form-fit portion [0097] 23 transfer member [0098] 24, 24, 24 actuator [0099] 25 bearing member [0100] 26, 26 spring member [0101] 27 overload clutch [0102] 28 axial spring member [0103] 29 axial spring member support [0104] 30, 30, 30, 30 service brake assembly [0105] 31, 31, 31, 31 service brake caliper (service brake pad carrier assembly) [0106] 32, 32, 32, 32 service brake pad [0107] R rotational axis [0108] rPB radial park brake pad distance [0109] rSB radial service brake pad distance
