US-20260126091-A1 - Heavy Vehicle Brake Assembly

Abstract

A heavy-vehicle brake assembly includes a braking element including friction material having an engaging face, the braking element configured to be actuated in a braking operation so that the engaging face of the friction material engages a braking surface to slow a heavy-vehicle; and a wear sensor assembly. The wear sensor assembly comprises: an ultrasonic sensor for emitting and detecting high-frequency sound waves; and a sacrificial member having an engaging face arranged to face the braking surface, wherein the sacrificial member is arranged such that sound waves emitted by the ultrasonic sensor pass through the sacrificial member; wherein the engaging face of the sacrificial member is flush with the engaging face of the friction material of the braking element and the sacrificial member is configured to actuate together with the braking element during the braking operation so that the engaging face of the sacrificial member also engages the braking surface.

Inventors

• Sean Cleary
• Paul A. Thomas
• Rhys Watkins
• Simon Duggan
• Daniel Jenkins
• Gopala K. VENUGOPALA

Assignees

• MERITOR HEAVY VEHICLE BRAKING SYSTEMS (UK) LIMITED

Dates

Publication Date

20260507

Application Date

20240614

Priority Date

20230614

Claims (20)

1. 1 . A heavy vehicle brake assembly comprising: a braking element including friction material, the braking element configured to be actuated in a braking operation in the direction of a braking surface so that an engaging face of the friction material contacts the braking surface to slow a heavy vehicle; and a wear sensor assembly for detecting the wear of the friction material, the wear sensor assembly configured to be actuated together with the braking element during the braking operation so that an engaging face of the wear sensor assembly also contacts the braking surface, wherein the wear sensor assembly comprises a compliant arrangement configured to allow compression of the wear sensor assembly when the engaging face of the wear sensor assembly contacts the braking surface.
2. 2 . The heavy vehicle assembly of claim 1 , wherein the compliant arrangement comprises a resilient element configured to be compressed during the braking operation and expand after the braking operation to move the engaging face of the wear sensor assembly in the direction of the braking surface.
3. 3 . The heavy vehicle assembly of claim 2 , wherein the compliant arrangement comprises a first member fixed relative to the braking element and a second member fixed relative to the wear sensor assembly, wherein the second member is movable relative to the first member along an axis that is perpendicular to the braking surface.
4. 4 . The heavy vehicle assembly of claim 3 , wherein the resilient element is located between the first member and the second member of the compliant arrangement.
5. 5 . The heavy vehicle assembly of claim 4 , wherein the resilient element is located between radially extending opposing surfaces of the first member and the second member.
6. 6 . The heavy vehicle assembly of claim 3 , wherein the second member is located radially inwardly of the first member.
7. 7 . The heavy vehicle assembly of claim 1 , wherein the braking element has a support surface for the friction material, at least one of the support surface and friction material comprise a slot or a recess to locate the wear sensor assembly, and the support surface and friction material each have a perimeter and the slot intersects the perimeter of the support surface and the perimeter of the friction material.
8. 8 . (canceled)
9. 9 . The heavy vehicle braking assembly of claim 7 , wherein the first member of the compliant arrangement locates in the slot of the support surface and is fixed to the support surface of the braking element, optionally wherein the first member is a clip configured to locate in the slot of the support surface with an interference fit and the second member is a sleeve configured to slide within the clip, optionally wherein the slot and the clip are substantially U-shaped.
10. 10 . The heavy vehicle braking assembly of claim 7 , wherein the support surface and friction material each have a perimeter and comprise a recess in the form of a through hole spaced from the perimeter of the support surface and the perimeter of the friction material.
11. 11 . ) The heavy vehicle braking assembly of claim 10 , wherein at least a portion of the second member of the compliant arrangement locates in the through hole of the support surface and the first member is fixed to the support surface of the braking element, optionally wherein the second member is fixed to the support surface by an elongate fastening element, optionally wherein the first member is configured to slide on the fastening element relative to the second member, optionally where the fastening element locates a resilient element.
12. 12 . The heavy vehicle braking assembly of claim 3 , wherein the extent of relative movement between the first member and the second member is limited by at least one stop surface, the braking element has a support surface for the friction material and the stop surface is on the second member and is configured to contact the support surface or the first member to limit return movement towards the braking surface, and the stop surface is a first stop surface and the second member further comprises a second stop surface for contacting the support surface of the first member to limit actuation movement away from the braking surface.
13. 13 .- 14 . (canceled)
14. 15 . The heavy vehicle braking assembly of claim 1 , wherein the wear sensor assembly further comprises: an ultrasonic sensor for emitting and detecting high-frequency sound waves; and a sacrificial member having the engaging face of the wear sensor assembly that is arranged to face the braking surface, wherein the sacrificial member is arranged such that sound waves emitted by the ultrasonic sensor pass through the sacrificial member.
15. 16 . A heavy-vehicle brake assembly, comprising: a braking element including friction material having an engaging face, the braking element configured to be actuated in a braking operation so that the engaging face of the friction material engages a braking surface to slow a heavy-vehicle; and a wear sensor assembly comprising: an ultrasonic sensor for emitting and detecting high-frequency sound waves; and a sacrificial member having an engaging face arranged to face the braking surface, wherein the sacrificial member is arranged such that sound waves emitted by the ultrasonic sensor pass through the sacrificial member; wherein the engaging face of the sacrificial member is flush with the engaging face of the friction material of the braking element and the sacrificial member is configured to actuate together with the braking element during the braking operation so that the engaging face of the sacrificial member also engages the braking surface.
16. 17 . The heavy-vehicle brake assembly of claim 16 , wherein the sacrificial member is fixed relative to the braking element.
17. 18 . (canceled)
18. 19 . The heavy-vehicle brake assembly of claim 16 , wherein the braking element comprises a recess extending through the friction material, and the sacrificial member is located within the recess, and the recess in the friction material is spaced from radial and circumferential edges of the braking element.
19. 20 . (canceled)
20. 21 . The heavy-vehicle brake assembly of claim 16 , wherein the sacrificial member is arranged between the ultrasonic sensor and the braking surface and is fixed to the ultrasonic sensor.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the U.S. National Phase of PCT/EP 2024/066627 Filed Jun. 14, 2024, which claims priority to EP 23179290.4 Filed Jun. 14, 2023, the disclosure of which is hereby incorporated in its entirety by reference herein. TECHNICAL FIELD The present disclosure relates to a heavy vehicle brake assembly, particularly to a wear sensor assembly for determining the wear of braking elements. BACKGROUND There are various methods for detecting wear in brakes for heavy vehicles. Such systems are an important safety feature because they help ensure that braking elements are replaced before they become too worn to provide effective stopping power. This can help prevent accidents and increase the overall safety of the vehicle. Additionally, by detecting wear early, such systems can help reduce maintenance costs by allowing brake elements to be replaced before they cause damage to other parts of the brake system, such as the brake rotors or drums. In some brakes, a pad wear warning indicator (PWWI) device is provided. This is typically a device that is located within the friction material of a braking element of the brake. When the friction material has worn to a predetermined amount, the PWWI will come into contact with the braking surface (e.g. the surface of a brake rotor in a disc brake or an inner surface of a brake drum in a drum brake) and make a noise that acts as a signal to the user that the braking element should be replaced. In other arrangements, a wire is located in the friction material that is in a loop to create a circuit. When the friction material is worn by enough, the circuit is broken to indicate that the friction material has reached a wear threshold. Alternatively, a more advanced solution is to include a constant wear sensor (CWS). Known CWS systems measure an internal component of the brake to estimate total friction wear. For example, in a disc brake, a CWS will measure the expansion of the adjuster mechanism to estimate total frictional wear, which is made up of the wear of the inboard brake pad, the outboard brake pad and the brake rotor. It would be desirable, however, to provide live measurements of the wear of individual braking elements as this could help diagnose issues with the brake such as differential wear. SUMMARY A first aspect of the present teachings provides a heavy-vehicle brake assembly, comprising: a braking element including friction material having an engaging face, the braking element configured to be actuated in a braking operation so that the engaging face of the friction material engages a braking surface to slow a heavy-vehicle; and a wear sensor assembly comprising: an ultrasonic sensor for emitting and detecting high-frequency sound waves; and a sacrificial member having an engaging face arranged to face the braking surface, wherein the sacrificial member is arranged such that sound waves emitted by the ultrasonic sensor pass through the sacrificial member; wherein the engaging face of the sacrificial member is flush with the engaging face of the friction material of the braking element and the sacrificial member is configured to actuate together with the braking element during the braking operation so that the engaging face of the sacrificial member also engages the braking surface. Ultrasonic (US) sensors are known for thickness measurement by monitoring the time delay between sending and receiving of a signal. However, it has been found that such US sensors are not suitable for measuring the remaining friction material of a braking element due to complexities introduced by there being a combination of materials (e.g. a steel backplate and a different friction material) as well as the isotropic nature of friction materials (typically a non-uniform compound with high metallic content). However, with the current arrangement, as the engaging face of the sacrificial member and the engaging face of the friction material are flush, they both engage the braking surface during a braking operation and wear at the same rate. Accordingly, sound waves emitted by the ultrasonic sensor through the sacrificial member are detected in order to provide data indicating the amount of material remaining in the sacrificial member. This data can then be used to determine the wear of the friction material, which will correspond to the wear of the sacrificial member. This can enable live monitoring of the wear of the individual braking elements without requiring any change to the composition of the friction material or the structure of the braking element. This arrangement can also be retrofitted to existing heavy-vehicle brakes. The sacrificial member may be fixed relative to the braking element. This helps to ensure that the sacrificial member and the braking element actuate together during the braking operation. The sacrificial member may be fixed to the braking element. Fixing the sacrificial member to the braking element further helps