Brake assembly for large vehicles

Abstract

A brake assembly for a heavy vehicle is provided. The brake assembly includes a braking element comprising a friction material having an engagement surface, which is configured to act in a braking operation so that the engagement surface of the friction material engages with a braking surface to decelerate the heavy vehicle, and a wear sensor assembly. The wear sensor assembly includes an ultrasonic sensor for emitting and detecting high-frequency sound waves and a sacrificial member having an engagement surface positioned opposite the braking surface. The sacrificial member is positioned so that sound waves emitted from the ultrasonic sensor pass through the sacrificial member. The engagement surface of the sacrificial member is flush with the engagement surface of the friction material of the braking element. The sacrificial member is configured to act together with the braking element during a braking operation so that the engagement surface of the sacrificial member also engages with the braking surface.

Description

Technical Field

[0001] The present disclosure relates to a brake assembly for large vehicles, particularly a wear sensor assembly for determining wear of a braking element.

Background Art

[0002] There are various methods for detecting wear in brakes for large vehicles. Such systems are an important safety feature as they help to ensure that braking elements are replaced before they wear too much to provide effective braking force. This can help to prevent accidents and enhance the overall safety of the vehicle. Additionally, by detecting wear early, such systems can help to reduce maintenance costs by making it possible to replace braking elements before they damage other parts of the braking system, such as brake rotors or drums.

[0003] Some brakes include a pad wear warning indicator (PWWI) device. This is typically a device placed within the friction material of the braking element of the brake. When the friction material wears to a predetermined amount, the PWWI contacts the braking surface (e.g., the surface of the brake rotor in a disc brake or the inner surface of the brake drum in a drum brake) and emits a sound that acts as a signal to inform the user that the braking element should be replaced. In other configurations, a loop-shaped wire forming a circuit is placed within the friction material. When the friction material wears sufficiently, the circuit is broken, indicating that the friction material has reached the wear threshold.

[0004] Alternatively, as a more advanced solution, a constant wear sensor (CWS) can be provided. Known CWS systems measure internal components of the brake to estimate the total wear amount. For example, in a disc brake, the CWS measures the extension of an adjustment mechanism to estimate the total wear amount, which is composed of the wear of the inner brake pad in the vehicle width direction, the outer brake pad in the vehicle width direction, and the brake rotor.

[0005] However, being able to measure the wear of individual braking elements in real time is desirable because it helps in diagnosing brake problems such as differential wear. [Overview of the Initiative]

[0006] A first aspect of this teaching provides a brake assembly for a heavy vehicle, the assembly comprising a braking element including a friction material having an engagement surface, the braking element configured to act in a braking operation such that the engagement surface of the friction material engages with a braking surface to decelerate the heavy vehicle, and a wear sensor assembly, the wear sensor assembly comprising an ultrasonic sensor for emitting and detecting high-frequency sound waves, and a sacrificial member having an engagement surface positioned opposite the braking surface, the sacrificial member being positioned such that sound waves emitted by the ultrasonic sensor pass through the sacrificial member, the engagement surface of the sacrificial member being flush with the engagement surface of the friction material of the braking element, and the sacrificial member being configured to act together with the braking element during a braking operation so that the engagement surface of the sacrificial member also engages with the braking surface.

[0007] Ultrasonic (US) sensors are known to measure thickness by monitoring the time delay between signal transmission and reception. However, such US sensors are known to be unsuitable for measuring residual friction material in braking elements due to the complexity arising from material combinations (e.g., steel backplates and different friction materials) as well as the isotropy of the friction material (typically a non-uniform compound with a high metal content). However, in the current configuration, the engagement surface of the sacrificial member and the engagement surface of the friction material are flush, so both engage with the braking surface during braking and wear at the same rate. Therefore, by detecting sound waves emitted by the ultrasonic sensor and passing through the sacrificial member, data indicating the amount of material remaining on the sacrificial member can be provided. This data can then be used to determine the wear of the friction material corresponding to the wear of the sacrificial member. This enables real-time monitoring of wear on individual braking elements without changing the composition of the friction material or the structure of the braking element. This configuration can also be retrofitted to existing brakes for heavy vehicles.

[0008] The sacrificial member may be fixed relative to the braking element.

[0009] This configuration helps ensure that the sacrificial member and the braking element operate together reliably during braking.

[0010] The sacrificial member may be fixed to the braking element.

[0011] Securing the sacrificial member to the braking element helps to further ensure that the sacrificial member and the braking element work together during braking. Furthermore, it means that the sacrificial member and the braking element can be supplied as a single assembly, which can help limit the use of unauthorized replacement braking elements, a safety concern.

[0012] The braking element may have a recess that extends through the friction material. The sacrificial member may be placed within this recess.

[0013] This arrangement helps ensure that both the friction material and the sacrificial element engage reliably with the braking surface during braking. This arrangement has been used in conventional brake assemblies to position known pad wear warning indicator devices, and is convenient because, when such devices are no longer needed, this position can be repurposed for the sacrificial member in existing braking elements, without requiring any changes to the manufacturing process for new braking elements.

[0014] The recesses within the friction material may be spaced apart from the radial and circumferential edges of the braking element.

[0015] This helps ensure that the sacrificial member does not come into contact with the braking surface and interfere with the operation of the brakes during braking.

[0016] The sacrificial member may be placed between the ultrasonic sensor and the braking surface.

[0017] This configuration ensures that high-frequency sound waves from the ultrasonic sensor pass through the sacrificial member and collide with the engagement surface of the sacrificial member. A portion of these waves are reflected back to the ultrasonic sensor and detected, making it possible to determine the amount of material removed from the sacrificial member in the direction of the braking surface.

[0018] The sacrificial member may be fixed to the ultrasonic sensor.

[0019] This configuration allows the sacrificial member and the ultrasonic sensor to be provided together as a single assembly, helping to ensure that the ultrasonic sensor is optimally aligned with the sacrificial member.

[0020] The sacrificial member may be elongated and positioned so that its longitudinal axis extends perpendicular to the engagement surface of the friction material of the braking element.

[0021] This ensures that the sacrificial member extends to a length sufficient to match the total depth of the friction material of the braking element, while minimizing the cross-sectional area of ​​the sacrificial member in contact with the braking surface relative to the area of ​​the friction material in contact with the braking surface, thereby ensuring that braking performance is not significantly negatively affected.

[0022] The sacrificial member may be cylindrical in shape. The sacrificial member may be located in a corresponding cylindrical recess of a housing configured to house an ultrasonic sensor.

[0023] This shape is easy to manufacture, and because precise rotational direction around the longitudinal axis is not a concern, it helps the user correctly install the sacrificial component during assembly.

[0024] The sacrificial member may be formed from a homogeneous material.

[0025] This material allows sound waves from an ultrasonic sensor to easily pass through the sacrificial member, enabling reliable detection without causing significant interference that affects the signal.

[0026] The material of the sacrificial member may have heat resistance. The material may have the same compressibility as the friction material of the braking element.

[0027] This configuration helps to ensure that the engagement surface of the sacrificial member remains flush with the engagement surface of the braking element and that the sacrificial member does not wear too quickly.

[0028] The material of the sacrificial member may be configured to be softer than the braking surface.

[0029] This configuration is beneficial in that it helps to ensure proper functioning and avoid damage to the braking surface.

[0030] In a second aspect, a drum brake is provided that includes the large vehicle brake assembly of the above aspect. The braking surface is the inner surface of a drum that is rotationally fixed to the wheel. The braking element is a brake shoe having a brake lining of friction material.

[0031] The drum brake may include a plurality of sacrificial members and a plurality of brake shoes. Each sacrificial member may correspond to a respective brake shoe.

[0032] By using a plurality of sacrificial members where each sacrificial member corresponds to each of the plurality of brake shoes, differential wear, that is, the case where the friction material of one brake shoe wears at a different rate from the friction material of one of the other brake shoes, can be detected. This information can be an indicator of brake failure and is thus useful in preventing more serious safety problems.

[0033] In a third aspect, a disc brake is provided that includes the large vehicle brake assembly of the first aspect. The braking surface is a rotor that is rotationally fixed to the wheel, and the braking element is a brake pad having a friction material. The brake pad may have a back plate. The friction material may be fixed to the back plate.

[0034] A disc brake may comprise multiple sacrificial members and multiple brake pads, where each sacrificial member corresponds to a respective brake pad.

[0035] By using multiple sacrificial members, each corresponding to a different brake pad, differential wear can be detected, i.e., when the friction material of one brake pad wears at a different rate than the friction material of another brake pad. This information can serve as an indicator of brake failure and is therefore useful in preventing more serious safety problems.

[0036] In a fourth embodiment, a brake assembly for a heavy vehicle is provided, comprising a braking element and a wear sensor assembly for detecting wear of a friction material, wherein the braking element includes a friction material and is configured to act toward the braking surface in a braking operation such that the engaging surface of the friction material contacts the braking surface to decelerate the heavy vehicle, and the wear sensor assembly is configured to act together with the braking element during a braking operation such that the engaging surface of the wear sensor assembly also contacts the braking surface. The wear sensor assembly has a compliant configuration configured to allow compression of the wear sensor assembly when the engaging surface of the wear sensor assembly contacts the braking surface.

[0037] When the braking element and wear sensor assembly come into contact with the braking surface, the wear sensor assembly can be compressed by the compliant configuration. Since the friction material is compressed during braking, this configuration helps ensure that the wear sensor assembly is compressed to at least the same extent as the friction material. This helps avoid the risk of the wear sensor assembly protruding from the friction material due to greater compression of the friction material. In other words, the engagement surface of the wear sensor assembly is coplanar with the engagement surface of the friction material. This is undesirable because a large portion of the reaction force from the braking element contacting the braking surface to decelerate the vehicle would pass through the wear sensor assembly, potentially damaging its delicate components. The compliant configuration helps ensure that a large portion of the reaction force is instead distributed around the wear sensor assembly. For example, much of the reaction force passes through the friction material to the support surface of the braking element and then around the wear sensor assembly along the load path to the vehicle brake's fixed components, such as the brake carrier or brake caliper.

[0038] The compliant configuration may include an elastic element configured to be compressed during braking and restored after braking to move the engagement surface of the wear sensor assembly toward the braking surface.

[0039] The elastic element, when compressed, helps ensure that the wear sensor assembly does not protrude from the friction material when the friction material is compressed. The elastic element then returns to its original state when the brake is released, ensuring that the engagement surface of the wear sensor assembly is returned to the braking surface, thus ensuring it is in the correct position for the next braking action.

[0040] The compliant configuration may include a first member fixed relative to the braking element and a second member fixed relative to the wear sensor assembly. The second member may be movable relative to the first member along an axis perpendicular to the braking surface.

[0041] Since the first and second members are movable relative to each other but fixed to different parts, the wear sensor assembly is movable relative to the braking element and can be compressed and extended toward and away from the braking surface.

[0042] The elastic element may be placed between the first and second members of the compliant configuration.

[0043] This is a compact configuration that allows the wear sensor assembly to be compressed and expanded as needed.

[0044] The elastic element may be positioned between the radially extending opposing surfaces of the first and second members.

[0045] The radially extending surface provides a suitable surface for the elastic element to act on, causing the second member to move along the axis relative to the first member, i.e., toward and away from the braking surface.

[0046] The second member may be positioned radially inward of the first member.

[0047] This helps reduce the space required for a compliant configuration.

[0048] The braking element may have a support surface for the friction material. The support surface and / or the friction material may have slots or recesses for arranging the wear sensor assembly.

[0049] The slot or recess provides a precise position for the wear sensor assembly, helping to ensure that the wear sensor assembly is accurately positioned relative to the braking element.

[0050] The support surface and the friction material may each have a periphery. The slots may intersect with the periphery of the support surface and the periphery of the friction material.

[0051] Because the slots intersect with the periphery of the support surface and the periphery of the friction material, the wear sensor assembly can be positioned in place simply by inserting it into the slots, thus simplifying assembly. This is useful, for example, when the braking element is already located within the brake, allowing the wear sensor assembly to be installed from above without removing the braking element from the brake.

[0052] The first member of the compliant configuration may be positioned within a slot in the support surface. The first member of the compliant configuration may be fixed to the support surface of the braking element. The first member may be a clip configured to be positioned within a slot in the support surface by interference fit. The second member may be a sleeve configured to slide within the clip. The slot and clip may be substantially U-shaped.

[0053] The clip can be installed in a simple manner and can be secured to the support surface without requiring additional parts or further operation. The slot and the U-shape of the clip allow for easy insertion of the sleeve.

[0054] The support surface and the friction material may each have a periphery. The support surface and the friction material may also have recesses in the form of through holes spaced apart from the periphery of the support surface and the periphery of the friction material.

[0055] This is an alternative assembly method in which, for example, the wear sensor assembly can be passed through the support surface from the rear side opposite to the front side that supports the friction material. This simplifies assembly because the wear sensor assembly is guided into the correct position by the through-hole during installation.

[0056] At least a portion of the second member of the compliant configuration may be positioned within a through-hole in the support surface. The first member may be fixed to the support surface of the braking element. The second member may be fixed to the support surface by an elongated fastening element. The first member may be configured to slide on the fastening element relative to the second member. The fastening element may include an elastic element.

[0057] This provides a reaction surface for a compliant configuration and forms a load path through the support surface of the braking element.

[0058] The relative movement between the first member and the second member may be limited by at least one stopping surface.

[0059] The stopping surface allows the relative movement of the first and second members to be controlled as desired. This helps to ensure that the relative movement does not become excessive.

[0060] The braking element may have a support surface for the friction material. The stopping surface may be on a second member. The stopping surface may be configured to contact the support surface or the first member to restrict movement toward the braking surface.

[0061] This helps ensure that the correct relative positioning and engagement surfaces are flush before the next braking action.

[0062] The stopping surface may be a first stopping surface. The second member may further include a second stopping surface for contacting a support surface or the first member in order to restrict the operating movement away from the braking surface.

[0063] The second member may be a sleeve having first and second radially extending flanges. The first stop surface may be on the first flange. The second stop surface may be on the second flange.

[0064] The wear sensor assembly may further include an ultrasonic sensor for emitting and detecting high-frequency sound waves, and a sacrificial member having an engagement surface of the wear sensor assembly positioned opposite the braking surface, wherein the sacrificial member is positioned so that sound waves emitted by the ultrasonic sensor pass through the sacrificial member.

[0065] Since the engagement surface of the sacrificial member is flush with the engagement surface of the friction material during braking, the sacrificial member wears down at the same rate as the friction material. By detecting the amount of wear on the sacrificial member, the wear of the friction material can be determined.

[0066] Each elastic element may be a spring washer, corrugated washer, spring, or compressible spacer.

[0067] Such elastic elements are particularly well-suited to current applications where deflection is small. They are easy to assemble and widely available.

[0068] Within the scope of this application, the various aspects, embodiments, examples, and alternatives described in the preceding paragraphs, claims, and / or the following description and drawings, in particular their individual features, are expressly intended to be adopted independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination unless such features are incompatible. The applicant reserves the right to modify any claim originally filed, or to file any new claim, including the right to amend any claim originally filed to be dependent on and / or incorporated to any other claim, even if not originally so. [Brief explanation of the drawing]

[0069] One or more embodiments of the present invention are described below, by reference only to the accompanying drawings. [Figure 1A] This is a perspective view of the wear sensor assembly. [Figure 1B] Figure 1A is a side view of the wear sensor assembly. [Figure 1C] This is a cross-sectional view of the wear sensor assembly shown in Figure 1A, passing through plane 1C-1C. [Figure 2] This is a perspective view of a disc brake for large vehicles. [Figure 3] Figure 2 is a cross-sectional view of a large vehicle disc brake passing through plane 2-2, including the wear sensor assembly shown in Figure 1A. [Figure 4] This is a magnified view of a portion of Figure 3. [Figure 5] This is a perspective view of an alternative disc brake for large vehicles. [Figure 6] Figure 5 is a cross-sectional view of a large vehicle disc brake passing through plane 6-6, including the wear sensor assembly shown in Figure 1A. [Figure 7] This is a perspective view of a drum brake for large vehicles. [Figure 8] Figure 7 is a cross-sectional view of a drum brake for a large vehicle, passing through plane 8-8, and includes the wear sensor assembly shown in Figure 1A. [Figure 9] This is a magnified view of a portion of Figure 8. [Figure 10] This is a perspective view of an alternative brake assembly for a large vehicle. [Figure 11] This is a cross-sectional view of a brake assembly for a large vehicle shown in Figure 10, passing through plane 11-11. [Figure 12] Figure 10 is a perspective view of the wear sensor assembly of a brake assembly for a large vehicle. [Figure 13] Figure 12 is an exploded view of the wear sensor assembly. [Figure 14] This is a perspective view of an alternative brake assembly for a large vehicle. [Figure 15] Figure 14 is a front view of a brake assembly for a large vehicle. [Figure 16] Figures 14 and 15 show cross-sectional views of a brake assembly for a large vehicle, passing through plane 16-16, with the wear sensor assembly in the first state. [Figure 17] Figures 14 and 15 show cross-sectional views of a brake assembly for a large vehicle, passing through plane 16-16, with the wear sensor assembly in the second state. [Figure 18] Figure 14 is a perspective view of the wear sensor assembly of a brake assembly for a large vehicle. [Figure 19] Figure 18 is an exploded view of the wear sensor assembly. [Figure 20] Figure 10 is an exploded view of a brake assembly for a large vehicle. [Modes for carrying out the invention]

[0070] Figures 1A to 1C show the wear sensor assembly 30. The wear sensor assembly 30 is used to determine the amount of wear on the friction material of the braking element and can be used in various different heavy vehicle brakes, as shown in the examples in Figures 2 to 9 and described in more detail below. Figures 2 to 4 show a pneumatically operated disc brake 2 including the wear sensor assembly 30. Figures 5 and 6 show a hydraulically operated disc brake 102 including the wear sensor assembly 30. Figures 7 to 9 show a drum brake 202 including the wear sensor assembly 30.

[0071] First, looking at Figures 1A to 1C, the wear sensor assembly 30 is shown in detail. In this embodiment, the wear sensor assembly 30 includes a housing 33, an ultrasonic sensor 32 for emitting and detecting high-frequency sound waves, and a sacrificial member 40. The ultrasonic sensor 32 is any suitable sensor including a transducer for generating high-frequency ultrasonic waves, which are emitted from the sensor and reflected by a hard surface or an interface between two different materials, for example, in this embodiment, the interface between the sacrificial member 40 and the air. Examples of suitable transducers are piezoelectric transducers or electromagnetic acoustic transducers (EMATs). The detected reflected sound waves can be transmitted by a connecting wire 36, or wirelessly in other embodiments, to a suitable controller (not shown), and the transmitted data can be used, for example, to determine the amount of material in the sacrificial member 40, for example, its current length. As described below, such data can be used to determine the amount of wear on the friction material of a braking element.

[0072] In this embodiment, the sacrificial member 40 has an elongated shape with a longitudinal axis xx. In this embodiment, the sacrificial member is cylindrical, i.e., has a circular cross-section, but it will be understood that there are various other shapes in which the sacrificial member 40 can perform its function. For example, the sacrificial member 40 may have a square cross-section, a triangular cross-section, or any other suitable shape. In this embodiment, the sacrificial member 40 has a constricted end 44 which has a smaller outer diameter and cross-sectional area than the rest of the sacrificial member 40. The end 44 has an end face 45 configured to face the ultrasonic sensor 32, as will be described in more detail below. A stepped portion 46 connects the end 44 to the rest of the sacrificial member 40. In this embodiment, the stepped portion 46 and the end 44 help to more easily position the sacrificial member 40 within the recess 34 of the housing 33. In this embodiment, the recess 34 is a cylindrical cavity corresponding to the cylindrical sacrificial member 40, but it will be understood that the recess 34 may be any suitable shape. In this embodiment, the sacrificial member 40 is fixed to the housing 33 with a suitable adhesive, but in other embodiments, the sacrificial member 40 and the housing 33 each have corresponding threads and can be screwed together. Furthermore, since the ultrasonic sensor 32 is located within the housing, the sacrificial member 40, the housing 33, and the ultrasonic sensor 32 can all be provided as a single wear sensor assembly 30. Typically, the remaining portion of the recess 34 in the housing can be filled with epoxy resin or the like to accommodate the ultrasonic sensor 32. A through-hole in the end face of the housing 33 helps to enable this, as it fills the recess 34 and allows any excess to exit through the through-hole. However, in other embodiments, it will be understood that all components may be provided separately, as long as the sacrificial member 40 is located between the ultrasonic sensor 32 and the braking surface of the brake, and sound waves from the ultrasonic sensor 32 pass through the sacrificial member 40, are reflected, and detected.

[0073] In this embodiment, the couplant 43 is provided between the ultrasonic sensor 32 and the end face 45 of the sacrificial member 40. In this embodiment, there is no gap between the couplant 43 and the ultrasonic sensor 32, and no gap between the couplant 43 and the end face 45 of the sacrificial member 40. The couplant 43 acts as a bridge that helps ensure that sound waves are reliably transmitted to the sacrificial member 40 and that the signal is not adversely affected by passing through the air. In this embodiment, the couplant 43 is a solid disc made of any suitable material. However, in other embodiments, the couplant 43 may be a viscous liquid, such as a silicone-based or glycol-based gel.

[0074] In this embodiment, since the sacrificial member 40 is formed of a homogeneous material, sound waves from the ultrasonic sensor 32 easily pass through the sacrificial member 40, helping to ensure reliable detection without causing significant interference that affects the signal. Any suitable material can be used, but ideally the material of the sacrificial member should be heat-resistant so as to withstand the high temperatures reached by the brakes and should have similar compressibility to the friction material of the braking element. An example of a suitable material is a thermoplastic such as Vespec®.

[0075] The end of the sacrificial member 40 opposite the end 44 has an engagement surface 42. The engagement surface 42 is approximately perpendicular to the longitudinal axis xx. When installed in the brake, as will be described in more detail below, the sacrificial member 40 is positioned such that its longitudinal axis xx extends perpendicular to the engagement surface of the friction material of the braking element. Also, as will be described in more detail below, this helps the engagement surface 42 of the sacrificial member 40 to face the braking surface and ensure that it is flush with the engagement surface of the friction material of the braking element.

[0076] Figures 2 to 4 show the disc brake 2. Various orientations of the disc brake 2 are explained. In particular, the directions I in the vehicle width direction and O in the vehicle width direction refer to the general orientation of the disc brake 2 when mounted on a vehicle, and are based on the longitudinal centerline of the vehicle. The radial direction R refers to the direction based on the center of the brake rotor (axis AA), and is, for example, the direction in which brake pads are attached to or removed from the disc brake.

[0077] The function of such disc brakes 2 is well known, so I will not explain it in detail, but simply put, the brake carrier positions the braking elements opposite the braking surface. In this case, the braking surface is the opposite side of the rotor 10 which is rotatably fixed to the vehicle wheel, and the braking elements are the brake pad 6 on the inside in the vehicle width direction and the brake pad 8 on the outside in the vehicle width direction. The actuator 4 engages with the brake pad 6 on the inside in the vehicle width direction and presses it toward the rotor 10, and the reaction force causes the caliper to slide against the brake carrier and press the brake pad 8 on the outside in the vehicle width direction toward the rotor 10. The brake pad 6 on the inside in the vehicle width direction and the brake pad 8 on the outside in the vehicle width direction each include a back plate 12 on which friction material 14 is positioned. The friction material 14 has an engagement surface 16 positioned opposite the rotor 10. During braking, when the brake pad 6 on the inside in the vehicle width direction and the brake pad 8 on the outside in the vehicle width direction move toward the rotor 10, the engagement surfaces 16 of the brake pad 6 on the inside in the vehicle width direction and the brake pad 8 on the outside in the vehicle width direction engage with the opposite side of the rotor 10, causing the vehicle to decelerate.

[0078] As time passes, the friction material 14 of the brake pads 6 on the inside in the vehicle width direction and the brake pads 8 on the outside in the vehicle width direction wears down. Therefore, it is useful to know exactly when each brake pad 6, 8 should be replaced, and whether one of the brake pads 6, 8 is wearing down faster than the other, which may indicate a brake malfunction. In this embodiment, to do this, wear sensor assemblies 30 are provided on both sides of the rotor 10. Each sacrificial member 40 is positioned such that its engagement surface 42 is flush with the engagement surface 16 of the friction material 14 of the brake pad 6 on the inside in the vehicle width direction or the brake pad 8 on the outside in the vehicle width direction. Since the brake pads 6, 8 and the corresponding sacrificial members 40 are configured to act together during braking, the engagement surface 42 of the sacrificial member 40 also engages with the rotor 10. Therefore, as the friction material 14 wears down, the sacrificial members 40 wear down at the same rate. Therefore, the sound waves emitted from the ultrasonic sensor 32 through the sacrificial member 40 are reflected back to the ultrasonic sensor 32 upon contact with the engagement surface 42 by the interface between the material of the sacrificial member 40 and the surrounding air. The reflected sound waves are detected by the ultrasonic sensor 32 and provide data indicating the time delay between the transmission and reception of the sound waves, which indicates the amount of material remaining on the sacrificial member 40. This data can then be used to determine the wear of the friction material 14 corresponding to the wear of the sacrificial member 40, since the friction member 14 and the sacrificial member 40 are flush.

[0079] In this embodiment, the sacrificial member 40 is fixed to the brake pads 6, 8 by being positioned in a central region spaced apart from the circumferential and radial edges of the brake pads 6, 8. In this embodiment, this central region includes a recess 18 that penetrates the friction material 14. In this embodiment, the recess 18 penetrates the entire depth of the friction material in the axial direction, i.e., in a direction parallel to the central axis of rotation of the rotor 10. In this embodiment, the recess 18 has a circular cross-section corresponding to the cylindrical sacrificial member 40, but it can have any suitable cross-sectional shape. Since the recess 18 is used to position a pad wear warning indicator device known in conventional brake pads, the wear sensor assembly 30 can be retrofitted to existing brake pads 6, 8 at this location. In other embodiments, if the engagement surface 42 of the sacrificial member 40 is flush with the engagement surface 16 of the friction material 14 of the brake pad 6 on the inside in the vehicle width direction or the brake pad 8 on the outside in the vehicle width direction, and the sacrificial member 40 and the brake pad 6 on the inside in the vehicle width direction or the brake pad 8 on the outside in the vehicle width direction act together during braking, it will be understood that the ultrasonic sensor 32 and the sacrificial member 40 can be placed in any suitable position.

[0080] To prevent damage to the wear sensor assembly 30, it is beneficial to ensure that the load path through the sacrificial member 40 does not pass through the ultrasonic sensor 32 and damage it. For example, the sacrificial member 40 may be elastic, or alternative configurations may be provided to ensure that the load does not reach the ultrasonic sensor 32.

[0081] Figures 5 and 6 show alternative brakes for large vehicles. In this embodiment, a hydraulically actuated disc brake 102 is shown having an actuator 104, which has a hydraulically actuated piston for actinguating a brake pad 106 on the vehicle width side and a known parking brake device for holding the brake 102 in the actuated position as needed. The brake 102 also includes a brake pad 108 on the vehicle width side. As is most clearly shown in Figure 6, similar to the embodiments in Figures 2 to 4, the wear sensor assembly 30 is provided on the vehicle width side and the vehicle width side of the rotor (not shown).

[0082] Figures 7 to 9 show further alternative brakes for large vehicles. In this embodiment, a drum brake 202 having an actuator 204 is shown. In this embodiment, the braking elements are brake shoes 206, each having a friction material 214. The operation of such a drum brake 202 is well known and will not be described in detail, but in short, during braking, the actuator 204 acts the brake shoes 206 radially outward, and the friction material 214 of each brake shoe engages with the inner surface of a drum (not shown) that is rotatably fixed relative to the vehicle wheel, thereby slowing down the vehicle. As is most clearly shown in Figure 9, similar to the embodiments in Figures 2 to 6, the wear sensor assembly 30 is positioned opposite the braking surface (in this case, the inner surface of the drum) and is flush with the engagement surface 216 of the friction material 214. Thus, each wear sensor assembly 30 can detect wear on the sacrificial member 40 and determine the amount of wear on the friction material 214.

[0083] Although the embodiments are described using multiple wear sensor assemblies 30, it should be understood that this is not always necessary, and a single wear sensor assembly 30 may suffice.

[0084] An alternative brake assembly for heavy vehicles is described below and shown in Figures 10 to 13. Features that this brake assembly has in common with the previous configuration are indicated by the same number preceded by "3," and these features will not be described in detail to avoid duplication as much as possible.

[0085] If the load path during braking passes through the ultrasonic sensor 332, there is a risk that the wear sensor assembly 330 may be damaged. For example, the couplant 343 may burn out or be damaged, creating a void. Furthermore, the ultrasonic sensor 332 itself may be crushed. In this embodiment, a compliant configuration 350 is provided that helps prevent this situation.

[0086] Figures 10 to 13 show the compliant configuration 350 fixed to the brake pad 306 on the inner side in the vehicle width direction, as well as the compliant configuration 350 alone, allowing for a more detailed view of the components of the compliant configuration 350. The function of the compliant configuration 350 is to allow the engaging surface 342 of the wear sensor assembly 330 to move relative to the support surface of the braking element. In this embodiment, the compliant configuration 350 allows the engaging surface 342 of the wear sensor assembly 330 to move relative to the backplate 312 of the brake pad 306 on the inner side in the vehicle width direction when the engaging surface 316 of the friction material 314 and the engaging surface 342 of the wear sensor assembly 330 contact the rotor 310. As the friction material 314 is compressed during braking, this helps to ensure that the wear sensor assembly 330 is compressed to at least the same extent as the friction material. This helps to avoid a situation where the friction material 314 is compressed more than necessary, causing the wear sensor assembly 330 to protrude from the friction material 314, i.e., the engagement surface 342 of the wear sensor assembly 330 is no longer substantially flush with the engagement surface 316 of the friction material 314. This is undesirable because much of the reaction force from the braking element contacting the braking surface to decelerate the vehicle would pass through the wear sensor assembly 330, potentially damaging its delicate components. The compliant configuration 350 helps to ensure that most of the reaction force is instead distributed around the wear sensor assembly 330. For example, most of the reaction force passes through the friction material 314 to the support surface of the braking element, such as the backplate 312, and then around the wear sensor assembly 330 along a load path to a vehicle brake component fixed relative to the wheel, such as a brake carrier or brake caliper.

[0087] As can be seen most clearly in Figure 10, in this embodiment, the backplate 312 and friction material 314 include a slot 318 for arranging the wear sensor assembly 330. The slot 318 extends axially through the thickness of the backplate 312 and friction material 314. In this embodiment, the slot 318 penetrates the entire thickness of the backplate 312 and friction material 314, but in other embodiments, it will be understood that the slot 318 may only partially penetrate one or both of the backplate 312 and friction material 314. In this embodiment, the slot 318 intersects the periphery 320 of the backplate 312 as well as the periphery 322 of the friction material 314. The slot 318 is approximately semicircular, but in another embodiment, it will be understood that it may have any suitable shape corresponding to the shape of the wear sensor assembly 330. In this embodiment, the slot 318 intersects the radial upper surfaces of the backplate 312 and friction material 314. This is beneficial in that it simplifies assembly, as the wear sensor assembly 330 can simply be inserted radially inward into the slot 318 and placed in place. This is useful, for example, if the brake pad 306 on the vehicle width side is already positioned within the brake 302, as it allows the wear sensor assembly 330 to be positioned from above without removing the brake pad 306 on the vehicle width side from the brake 302. As will be described in more detail below, part of the compliant configuration 350 is fixed to the back plate 312, and the rest of the wear sensor assembly 330 is positioned within the slot 318.

[0088] Figures 12 and 13 show the compliant configuration 350 of the wear sensor assembly 330 in more detail. In this embodiment, the compliant configuration 350 includes a first member fixed relative to the back plate 312 of the brake pad 306 on the vehicle width side, and a second member movable axially relative to the first member. In this embodiment, the first member is in the form of a clip 352, and the second member is in the form of a sleeve 354. The compliant configuration 350 further includes an elastic element. In this embodiment, the elastic element is in the form of a spring washer 356. In this embodiment, in contrast to the wear sensor assembly 30 shown in Figures 1A to 1C, the housing 333 of the wear sensor assembly 330 has a smaller diameter than the sacrificial member 340, but the function and components are the same as those in Figures 1A to 1C. The clip 352, sleeve 354, and spring washer 356 each have through holes and are positioned on the housing 333 and can contact the sacrificial member 340. The spring washer 356 is positioned between the clip 352 and the sleeve 354. In this embodiment, the components of the wear sensor assembly 330 are arranged on axis yy as shown in Figure 13.

[0089] The clip 352 is molded to fit into a slot 318 in the backplate 312. In this embodiment, the clip 352 is interference-fitted to the slot 318, but in another embodiment, it may be fixed to the backplate 312 in any suitable manner. The clip 354 comprises a sleeve portion, the sleeve portion having a first flange 358 extending radially at a first end and a second flange 360 ​​extending radially at the opposite second end. The first and second flanges 358, 360 are positioned to engage with the inner and outer surfaces in the vehicle width direction of the backplate 312, respectively, in order to position the clip 352 axially. In this embodiment, the clip 352 is substantially annular but has a cutout portion to form an opening 353, so that the remainder of the wear sensor assembly 330 can be inserted into the clip 352 from above after the clip 352 has been positioned in the slot 318. In other words, the clip 352 is substantially U-shaped. Since the opening 353 is sandwiched in the flat cutting section, the clip 352 does not protrude radially upward from the upper surface of the back plate 12.

[0090] The sleeve 354 is configured to be positioned within the clip 352 and is slidable relative to the clip 352. In this embodiment, the sleeve 354 is positioned radially inward of the clip 352, which helps to reduce the space required for the compliant configuration 350. In this embodiment, the sleeve 354 has a sleeve portion, the sleeve portion having a first flange 366 extending radially at a first end and a second flange 368 extending radially at the opposite second end. In this embodiment, the second flange 368 extends radially more than the first flange 366. The sleeve 354 is configured to be positioned within the clip 352. The first flange 366 is positioned axially inward of the first flange 358 of the clip 352 in order to hold the sleeve 354 on the clip 352, i.e., to limit the sleeve 354 from moving too far outward in the vehicle width direction. In other words, the first flange 366 forms a first stop surface. The second flange 368 is positioned on the axial, vehicle-width-outward side of the second flange 360 ​​of the clip 352, thereby limiting the sleeve 354 from moving too far inward in the vehicle-width-outward direction. In other words, the second flange 368 forms a second stopping surface.

[0091] The surface of the second flange 368 facing outward in the vehicle width direction contacts the surface 370 of the sacrificial member 340 facing inward in the vehicle width direction. Therefore, when a force is applied to the engagement surface 342 of the sacrificial member 340 during braking, that force is transmitted to the second flange 68 of the sleeve 354.

[0092] The spring washer 356 is positioned between the opposing surfaces of the second flange 368 of the sleeve 354 and the second flange 360 ​​of the clip 352. The spring washer 356 can be specially selected to have a moderate springiness so that when a force is applied to the sleeve 354, that force is transmitted to the spring washer 356 via the second flange 368. In reaction, the spring washer 356 returns the force to the sleeve 354. In this way, the springiness of the spring washer 356 determines how compressible the compliant configuration 350 is. Typically, during braking, the friction material 314 is compressed axially by a maximum of 1-2 mm. Therefore, by selecting an elastic element configured to be compressed by approximately the same amount, it should be ensured that the friction material 314 on the engagement surface 316 and the engagement surface 342 of the sacrificial member 340 remain nearly flush. In this embodiment, the elastic element is a spring washer 356, but any suitable type of elastic element may be used. For example, it may be a corrugated washer, a compressible spacer, or a spring.

[0093] Figures 14 to 20 show another embodiment having a compliant configuration 450. Only the differences from the previous embodiment will be described. Similar components use the same reference number preceded by "4".

[0094] As can be seen in Figure 14, in this embodiment, at least a portion of the compliant configuration 450 is positioned on the vehicle width side of the back plate 412 of the brake pad 106 on the vehicle width side.

[0095] Figure 20 shows that in this embodiment, there are no slots intersecting the backplate 412 and the friction material 414. Instead, recesses are formed that are spaced apart from the periphery 420 of the backplate 412 and the periphery 422 of the friction material 414. In this embodiment, the recesses are through holes 418. At least a portion of the wear sensor assembly 430 is located in the through holes 418, as will be described in more detail below. As shown in Figures 19 and 20, in this embodiment, the components of the wear sensor assembly 430 are arranged on axis zz.

[0096] As most clearly shown in Figures 18 to 20, the compliant configuration 450 has a first member fixed to the backplate 412 in the form of a housing 452. Radially inward of the housing 452 is a second member that is axially movable relative to the first member. In this embodiment, the second member is in the form of a cylinder 454.

[0097] The housing 452 includes an axially extending annular sleeve portion 464. The outer end of the sleeve portion 464 in the vehicle width direction has a radially extending surface, giving the housing 452 a cup shape and a bottomed hole forming a radial inner surface 462 on the side of the radially extending surface facing outward in the vehicle width direction. The sleeve portion 464 is positioned around an axis zz and is configured to surround the cylinder 454. In this embodiment, the housing 452 is secured to the back plate 412 by at least one elongated fastening element. In this embodiment, the housing 452 is secured to the back plate 412 by three elongated fastening elements in the form of bolts 458. Each bolt 458 has a head and a shaft, the shaft of which is configured to be introduced from the vehicle width direction inside the housing through circumferentially distributed holes penetrating the radially extending surface of the housing 452. The head of the bolt 458 limits the degree of insertion as desired by engaging with the vehicle width direction inside surface of the radially extending surface of the housing 452. The shaft of the bolt 458 is positioned within the corresponding threaded hole in the backplate 412. However, it is understood that the housing 452 may be secured to the backplate 412 by any other suitable method. For example, different types of fastening elements may be used, or the housing 452 may be bonded or secured to the backplate 412 by suitable adhesive or welding.

[0098] The cylinder 454 has a blind hole 460 on its inner surface in the vehicle width direction. The blind hole 460 is sized to receive the housing 433 of the wear sensor assembly 430. The outer surface 461 of the cylinder 454 facing outward in the vehicle width direction surrounds the blind hole 460 and is configured to engage with the inner surface 470 of the sacrificial member 440 so that forces applied to the sacrificial member 440 are transmitted to the cylinder 454. In this embodiment, the cylinder 454 has a radially projecting flange 466 at its outer end in the vehicle width direction. The outer surface of the flange 466 in the vehicle width direction is configured to restrict the cylinder 454 from moving too far outward in the vehicle width direction. In other words, the outer surface of the flange 466 in the vehicle width direction forms a first stopping surface. In this embodiment, the outer surface of the flange 466 in the vehicle width direction is configured to restrict the movement of the cylinder 454 outward in the vehicle width direction by engaging with the inner surface of the back plate 412 in the vehicle width direction. The inner surface of flange 166 in the vehicle width direction is configured to restrict the cylinder 454 from moving too far in the vehicle width direction. In other words, the inner surface of flange 466 in the vehicle width direction forms a second stopping surface. In this embodiment, the inner surface of flange 466 in the vehicle width direction is configured to restrict the movement of cylinder 454 in the vehicle width direction by engaging with the radial inner surface 462 of housing 452. However, as will be explained below, due to the elastic element positioned between the inner surface of flange 466 in the vehicle width direction and the radial inner surface 462 of housing 452, cylinder 454 rarely comes into contact with housing 452.

[0099] The flange 466 has through holes, which are positioned so that bolts 458 pass through before being fixed to the backplate 412. The holes in the flange 466 are dimensioned so that there is a clearance between them and the bolts 458. This allows the cylinder 454 to slide axially on the bolts 458 against the housing 452. There is at least one elastic element between the widthwise inner surface of the flange 466 and the radially inner surface 462 of the housing 452. In this embodiment, there are three elastic elements in the form of wave springs 456 positioned on the three bolts 458 and engaging with the widthwise inner surface of the flange 466 and the radially inner surface 462 of the housing 452. As in the embodiments described above, the wave springs 456 can be specially selected to have a moderate springiness so that when a force is applied to the cylinder 454, that force is transmitted to the wave springs 456 via the flange 466. In reaction, the wave springs 456 return the force to the cylinder 454. In this way, the spring properties of the wave spring 456 determine how compressible the compliant configuration 450 is. In this embodiment, each elastic element is a wave spring 456, but any suitable type of elastic element may be used. For example, if the housing 452 is fixed to the back plate 412 in another way, there may be only one spring between the cylinder 454 and the housing 452.

[0100] When the word "or" is used, it should be interpreted as meaning "and / or." This means that the items being referenced are not necessarily mutually exclusive and may be used in any appropriate combination.

[0101] The present invention has been described with reference to one or more specific embodiments. However, it is understood that various changes and modifications can be made without departing from the scope of the invention as described in the claims.

[0102] For example, wear sensor assemblies 330, 430 having compliant configurations 350, 450 are described and illustrated only with respect to the brake pads 306, 406 on the inner side in the vehicle width direction. However, such configurations may also be provided for the brake pads 408, 408 on the outer side in the vehicle width direction, and it is understood that they are substantially mirror images of the configurations for the brake pads on the inner side in the vehicle width direction.

[0103] The braking element described and illustrated is a planar brake pad having a back plate as a support surface for the friction material. However, in other embodiments, one or more of the braking elements may be curved in shape, having a brake shoe as a support surface for the friction material. The wear sensor assemblies 330, 430 are suitable for use in various heavy vehicle brakes, such as pneumatic, hydraulic, or electrically operated brakes. The brakes may be disc brakes or drum brakes.

[0104] The attached claims describe specific combinations of the features described above. However, the scope of this disclosure is not limited to the specific combinations described in these claims. Rather, the scope of this disclosure is extended to encompass any combination of the features disclosed herein.

Claims

1. A brake assembly for large vehicles, A braking element including a friction material, wherein the braking element is configured to act in the direction of the braking surface during braking, so that the engaging surface of the friction material contacts the braking surface and slows down the large vehicle. A wear sensor assembly for detecting wear of the friction material, wherein the wear sensor assembly is configured to operate together with the braking element during the braking operation so that the engaging surface of the wear sensor assembly also contacts the braking surface. Equipped with, A brake assembly for a large vehicle, comprising a wear sensor assembly having a compliant configuration configured to allow the wear sensor assembly to be compressed when the engaging surface of the wear sensor assembly contacts the braking surface.

2. A brake assembly for a large vehicle according to claim 1, The compliant configuration has an elastic element, A brake assembly for a large vehicle, wherein the elastic element is configured to be compressed during the braking operation and to be restored after the braking operation to move the engagement surface of the wear sensor assembly toward the braking surface.

3. A brake assembly for a large vehicle according to claim 2, The compliant configuration comprises a first member fixed relative to the braking element and a second member fixed relative to the wear sensor assembly. A brake assembly for a large vehicle, wherein the second member is movable relative to the first member along an axis perpendicular to the braking surface.

4. A brake assembly for a large vehicle according to claim 3, The elastic element is disposed between the first member and the second member of the compliant configuration in a brake assembly for a large vehicle.

5. A brake assembly for a large vehicle according to claim 4, The elastic element is disposed between radially extending opposing surfaces of the first member and the second member in a brake assembly for a large vehicle.

6. A brake assembly for a large vehicle according to any one of claims 3 to 5, A brake assembly for a large vehicle, wherein the second member is positioned radially inward of the second member.

7. A brake assembly for a large vehicle according to any one of claims 1 to 6, The braking element has a support surface for the friction material, A brake assembly for a large vehicle, wherein at least one of the support surface and the friction material has a slot or recess for arranging the wear sensor assembly.

8. A brake assembly for a large vehicle according to claim 7, The support surface and the friction material each have a peripheral edge, A brake assembly for a large vehicle, wherein the slot intersects with the periphery of the support surface and the periphery of the friction material.

9. A brake assembly for a large vehicle according to claim 8, which is dependent on claim 3, The first member of the compliant configuration is positioned within the slot of the support surface and fixed to the support surface of the braking element. Optionally, the first member is a clip configured to be positioned in the slot of the support surface by interference fit, The second member is a sleeve configured to slide within the clip, A brake assembly for a large vehicle, wherein the slot and the clip are optionally U-shaped.

10. A brake assembly for a large vehicle according to claim 7, A brake assembly for a large vehicle, wherein the support surface and the friction material each have a periphery, and each has a recess in the form of a through hole spaced apart from the periphery of the support surface and the periphery of the friction material.

11. A brake assembly for a large vehicle according to claim 10, which is dependent on claim 3, At least a portion of the second member of the compliant configuration is disposed within the through hole in the support surface, The first member is fixed to the support surface of the braking element, Optionally, the second member is fixed to the support surface by an elongated fastening element. The first member is optionally configured to slide on the fastening element relative to the second member. A brake assembly for a large vehicle, wherein the fastening element optionally includes an elastic element.

12. A brake assembly for a large vehicle according to claim 3, A brake assembly for a large vehicle, wherein the range of relative movement between the first member and the second member is limited by at least one stopping surface.

13. A brake assembly for a large vehicle according to claim 12, The braking element has a support surface for the friction material, A brake assembly for a large vehicle, wherein the stopping surface is located on the second member and is configured to restrict return movement to the braking surface by contacting the support surface or the first member.

14. A brake assembly for a large vehicle according to claim 13, The aforementioned stopping surface is a first stopping surface, A brake assembly for a large vehicle, wherein the second member further comprises a second stopping surface that restricts the operating movement away from the braking surface by contacting the support surface or the first member.

15. A brake assembly for a large vehicle according to any one of claims 1 to 14, The wear sensor assembly comprises an ultrasonic sensor for emitting and detecting high-frequency sound waves, and a sacrificial member having the engagement surface of the wear sensor assembly, which is positioned to face the braking surface. The brake assembly for a large vehicle is arranged such that sound waves emitted from the ultrasonic sensor pass through the sacrificial member.

16. A brake assembly for large vehicles, A braking element comprising a friction material having an engagement surface, wherein the braking element is configured such that, when actuated during braking, the engagement surface of the friction material engages with the braking surface to decelerate a large vehicle. Wear sensor assembly and It has, The wear sensor assembly comprises an ultrasonic sensor for emitting and detecting high-frequency sound waves, and a sacrificial member having an engaging surface positioned opposite the braking surface. The sacrificial member is positioned such that sound waves emitted from the ultrasonic sensor pass through the sacrificial member. The engagement surface of the sacrificial member is flush with the engagement surface of the friction material of the braking element. A brake assembly for a large vehicle, wherein the sacrificial member is configured to act together with the braking element during the braking operation such that the engaging surface of the sacrificial member also engages with the braking surface.

17. A brake assembly for a large vehicle according to claim 16, A brake assembly for a large vehicle, wherein the sacrificial member is fixed relative to the braking element.

18. A brake assembly for a large vehicle according to claim 17, A brake assembly for a large vehicle, wherein the sacrificial member is fixed to the braking element.

19. A brake assembly for a large vehicle according to claim 18, The braking element includes a recess that extends through the friction material, The sacrificial member is located within the recess in the brake assembly for a large vehicle.

20. A brake assembly for a large vehicle according to claim 19, A brake assembly for a large vehicle, wherein the recess in the friction material is spaced apart from the radial and circumferential edges of the braking element.

21. A brake assembly for a large vehicle according to any one of claims 16 to 20, The sacrificial member is positioned between the ultrasonic sensor and the braking surface in a brake assembly for a large vehicle.

22. A brake assembly for a large vehicle according to claim 21, A brake assembly for a large vehicle, in which the sacrificial member is fixed to the ultrasonic sensor.

23. A brake assembly for a large vehicle according to any one of claims 16 to 21, A brake assembly for a large vehicle, wherein the sacrificial member has an elongated shape, and the longitudinal axis of the sacrificial member is positioned to extend in a direction perpendicular to the engagement surface of the friction material of the braking element.

24. A brake assembly for a large vehicle according to claim 23, A brake assembly for a large vehicle, wherein the sacrificial member is cylindrical and is located within a corresponding cylindrical recess of a housing configured to accommodate the ultrasonic sensor.

25. A brake assembly for a large vehicle according to any one of claims 16 to 24, The sacrificial member is formed from a homogeneous material. A brake assembly for a large vehicle, wherein, optionally, the material of the sacrificial member is configured to be softer than the braking surface.

26. A brake assembly for a large vehicle according to claim 25, A brake assembly for a large vehicle, wherein the material of the sacrificial member is heat-resistant and has the same compressibility as the friction material of the braking element.

27. A drum brake comprising a brake assembly for a large vehicle according to any one of claims 16 to 26, The braking surface is the inner surface of a drum that is rotatably fixed to the vehicle wheel. The braking element is a drum brake, wherein the braking element is a brake shoe having a brake lining made of the friction material.

28. A drum brake according to claim 27, The system comprises a plurality of sacrificial members and a plurality of brake shoes, Each of the aforementioned sacrificial members corresponds to each of the aforementioned brake shoes, forming a drum brake.

29. A disc brake comprising a brake assembly for a large vehicle according to any one of claims 16 to 26, The braking surface is a rotor that is fixed to the vehicle wheel for rotation. The braking element is a brake pad having the friction material, A disc brake wherein the brake pad optionally has a back plate, and the friction material is fixed to the back plate.

30. A disc brake according to claim 29, The system comprises a plurality of sacrificial members and a plurality of brake pads, Each of the aforementioned sacrificial members corresponds to each of the aforementioned brake pads, forming a disc brake.

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