Cross-Reference to Related Applications

[0001] The present application claims priority from Australian Provisional Patent Application No 2015903011 filed on 29 July 2015, the content of which is incorporated herein by reference.

Technical Field

[0002] The present disclosure relates to brake pads. Background

[0003] Brake systems, such as a friction brake, may include one movable surface, such as a rotating disc or drum, and a brake lining that is movable to contact the rotating disc. The contact between the movable surface and the brake lining results in friction force between the two surfaces which slows rotation of the movable surface.

[0004] In one application, the brake system is incorporated in a motor vehicle. The brake system is an important part of controlling the motor vehicle by selectively causing the vehicle to slow down as well as maintaining a stationary position when at a stop. When activated, the brake system may convert a substantial portion of the kinetic energy of the vehicle to thermal energy.

[0005] The friction between the brake lining and movable surface also results in wearing of one or both surfaces. Typically the brake lining is the consumable component that has the most wear. In a disc brake system, the consumable brake lining is part of a brake pad. Over time, wearing of these components can diminish the performance of the brake system and therefore these components may need to be serviced and replaced periodically.

[0006] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. [0007] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.

Summary

[0008] A brake pad comprising a friction body having: a friction surface; a sidewall, and an edge at an intersection of the friction surface and the sidewall. The brake pad is provided with visual indicia on the sidewall to indicate a state of wear of the friction body based on a position of the edge.

[0009] By providing visual indicia on the sidewall, a user may inspect the brake pad to determine the state of wear. Visual indicia on the sidewall may be advantageous as they may be easier for a user to see. This is compared to visual markings provided at the friction surface that may be obscured or removed by wear during use.

[0010] In the brake pad, the visual indicia may comprises one or more of: printed marking on the sidewall; paint on the sidewall; etching on the sidewall; stickers on the sidewall; and one or more setbacks in the sidewall. The visual indicia may also be provided by including a colouring agent in one or more parts of friction material in the friction body.

[0011] In the brake pad, the visual indicia comprises a pattern on the sidewall, wherein the pattern indicates the state of wear based on the position of the edge at the pattern.

[0012] In the brake pad, the visual indicia comprises textual information indicative of a state of wear.

[0013] In the brake pad, the visual indicia on the sidewall includes: a first portion proximal to the friction surface; and a second portion distal to the friction surface, wherein the visual indicia comprises a visual contrast between the first portion and the second portion. This may assist visual distinction between the first portion and the second portion. [0014] In the brake pad, the visual indicia may include a plurality of visual markings to indicate respective states of wear of the friction body. This may assist the user in providing further granularity regarding the state of wear. For example, that the brake pad is serviceable, the brake pad is serviceable but will require replacement in the near future, and the brake pad is worn and must be replaced, etc.

[0015] In the brake pad, the visual indicia comprise one or more characters. These characters may include letters and/or numbers to convey information to the user. In one example, the characters may include "75% remaining", "worn out", "replace", etc. Advantageously, this allows a user who may not be familiar with the particular brake pad to easily identify the state of wear without using instruments to measure the brake pad and cross reference the measurement with the product manual/specification sheet.

[0016] The sidewall may extend substantially perpendicular to the friction surface. This may assist in easy identification of the edge.

[0017] The brake pad may further comprise a backing plate supporting the friction body and located opposite the friction surface, wherein the brake pad is a component of a disc brake system of a motor vehicle.

[0018] A disc brake system comprising: a disc connected to a hub; a caliper having at least one brake pad described above, wherein the disc brake system is operable such that the friction surface is in contact with the disc.

Brief Description of Drawings

[0019] Examples of the present disclosure will be described with reference to:

[0020] Fig. 1(a) is a side view of a brake pad;

[0021] Fig. 1(b) is a top view of the brake pad in Fig. 1(a);

[0022] Fig. 1(c) is an end view of the brake pad in Fig. 1(a);

[0023] Figs. 2(a) to 2(e) illustrate a sequence of progressive states of wear of the brake pad in Fig. 1(a); [0024] Fig. 3(a) is a side view of another brake pad with visual indicia including a pattern;

[0025] Fig. 3(b) is a side view of another brake pad with visual indicia including a line;

[0026] Fig. 3(c) is a side view of another brake pad with visual indicia including a plurality of visual markings;

[0027] Fig. 4 is a side view of another brake pad with visual indicia including a plurality of lines and characters;

[0028] Fig. 5(a) is a side view of another brake pad with visual indicia including setbacks in a sidewall of the friction body;

[0029] Fig. 5(b) is an end view of the brake pad in Fig. 5(a);

[0030] Fig. 6 is a view of a disc brake system showing the visual indicia; and

[0031] Fig. 7(a) is a side view of another brake pad with visual indicia including a matrix pattern on a sidewall; and

[0032] Fig. 7(b) is a top view of the brake pad in Fig. 7(a). Description of Embodiments

Overview

[0033] Figs. 1(a) to 1(b) illustrate a brake pad 1 having a friction body 3. The friction body 3 includes a friction surface 5 a sidewall 7, and an edge 11 at an intersection of the friction surface 5 and the sidewall 7. Visual indicia 9 are provided on the sidewall 7 to indicate a state of wear of the friction body based on a position of the edge 11.

[0034] By providing the visual indicia on the sidewall 7, a user may easily inspect the brake pad 1 to determine the state of wear. Visual indicia 9 on the sidewall may be easily read and, in some examples, include text or other information. This is in contrast to markings (such as grooves) provided at the friction surface itself that may be removed, filled in with brake dust, or otherwise obscured. Description of the brake pad 1

[0035] The brake pad 1 may also include a backing plate 13 supporting the friction body 3, whereby the backing plate 13 is located opposite to the friction surface 5. The friction body 3 may be bonded to the backing plate 13, such as by adhesives. In some examples, the friction body 3 may be moulded to the backing plate 13. It is to be appreciated that the brake pad 1 may be attached to the backing plate 13 in other ways, such as with mechanical fasteners, such as rivets, screws, nut and bolt, etc. In some further examples, this may include combinations of one or more of these methods. The backing plate 13 also includes a pair of flanges 14 to assist positioning and attachment to brake calipers. The backing plate may be made of steel.

[0036] The friction body 3 is made of a friction material, such as semi-metallic, low metallic, ceramic, or non-asbestos organic. This material may desirably be heat resistant and have a stable (or predictable) co-efficient of friction throughout a specified temperature range. The friction body 3 may have a chamfer 8 at the leading (and/or trailing) portions of the friction surface 5. This may assist in reducing tendencies of the leading portion of the friction surface 5 to grab or catch irregularities in the rotating disc. The chamfer 8 may also reduce noise. The friction body 3 may be provided with a slot 12. This may relieve stresses in the friction body 3, which may be caused by contraction and expansion from varying temperatures. The slot 12 may also increase flexibility of the friction body 3 and provide a vent to assist cooling. The slot 12 may also aid removal of friction debris (i.e. brake dust).

[0037] The sidewall 7 may extend substantially perpendicular to the friction surface 5, which provides the edge 11 at a right angle (from the sidewall 7 and friction surface 5) that may assist in easy identification of the edge 11. This is in contrast to configurations with the sidewall 7 and the friction surface 5 at planes close to each other which may cause an ill-defined or a hard to perceive edge 11.

[0038] Referring to Fig. 1(a), the visual indicia 9 on the sidewall 7 includes a first portion 15 proximal to the friction surface 5 and a second portion distal 17 to the friction surface. The visual indicia 9 includes a visual contrast between the first portion 15 and the second portion 17. In this example, this is achieved by printing the second portion 17 with a lighter colour that is contrast with the first portion 15 on the sidewall 7. In some examples, the first portion 15 of the sidewall is the inherent colour of the friction body (i.e. without any printing). It is to be appreciated that providing the contrast between the first and second portion may be achieved with other ways. For example, the first portion 15 may have printing to contrast with an unprinted second portion 17. In another example, both the first and second portions may be printed with contrasting colours and/or tones. The visual indicia 9 may also include patterns to assist the contrast between the first and second portions 15, 17. In addition, the colour and/or patterns may be distinctive to assist in identifying that the brake pad 1 is of a type with visual indicia compared to other brake pads. Further variations will be discussed below.

[0039] At the boundary between the first portion 15 and second portion 17 is a demarcation line 19. In this example, the demarcation line 15 is representative of a state of wear, and in particular a state of wear (i.e. a threshold) such that the brake pad 1 should be replaced. This will be discussed with respect to Figs. 2(a) to 2(e)

Indicating the state of wear of the brake pad

[0040] The sequence in Figs 2(a) to 2(e) shows the remaining portions of the wear body in particular, 100%, 75%, 50%, 30% and 20% respectively. In the illustrated brake pad 1, the demarcation line 19 is provided at a position that represents 30% of the friction body 3 remaining. This position (and corresponding percentage) may be selected by the manufacture according to the specifications of the brake pad 1 and/or regulatory requirements. In one example, the demarcation line 15 is positioned so that the second portion 17 has a height of 4mm.

[0041] The brake pad 1 may be mounted to brake calipers 681 in a disc brake system 600 of a motor vehicle as illustrated in Fig. 6. The disc brake system 600 includes a rotating disc 683 connected to a hub 684. In use, the friction surface 5 of the friction body 3 is placed in contact with the rotating disc 683, whereby friction between the friction surface 5 and the rotating disc 683 converts kinetic energy, of the rotating disc 683, into thermal energy. A consequence of this friction is that the friction body 3 will progressively wear away, with the friction surface 5 retreating towards the backing plate 13, as shown in sequence from Figs. 2(a) to 2(e). The edge 11 formed at the junction of the friction surface 5 and the sidewall 7 also retreats with the friction surface towards the backing plate 13.

[0042] The state of wear of the friction body 3 may be determined by visual inspection of the position of the edge 11 compared with the visual indicia 9 on the sidewall 7. Visual inspection may be performed by first removing the brake pad 1 from the brake calipers. [0043] In some examples, as illustrated in Fig. 6, the brake pad 1 and brake calipers 681 may be configured such that the visual indicia 9 can be visually inspected by a user without removing the brake pad 1 from the brake caliper 681, (or separation of the brake pad 1 and/or brake caliper from the disc 683). Depending on the configuration, this may be done with, or without, removing the corresponding wheel. For example, the brake caliper may have an inspection aperture 685 or slot to allow the user to inspect the visual indicia of the brake pad 1 that is mounted to the brake caliper. In another example, visual inspection may be done by observing the brake pad 1 with a line of sight that forms an acute angle relative to the surface of the disc. This may be advantageous by allowing inspection of the state of wear of the brake pad 1 without the time and labour of removing and reinstalling the brake pad 1. This is in contrast to brake pads that have markings on the friction surface which would be difficult (if not impossible) to view due to obstruction by the remaining portions of the brake system (such as the brake caliper and disc).

[0044] During visual inspection, if the edge 11 is, with reference to the orientation in Figs. 2, above the demarcation line 19, this indicates that the brake pad 1 does not need to be replaced as there is sufficient material in the friction body 3. The demarcation line 19 may indicate a state of wear such that the brake pad 1 should be changed based on the average use of the vehicle. For example, the remaining friction body 3 below the demarcation line 19 (e.g. the second portion 17) may be include an amount of friction material that is expected to be worn off during average use of the brake pad 1 over a service cycle. For example, this may coincide with average wear over a 12 month service cycle of a vehicle. Alternatively, the user may visually inspect that at least part of the first portion 15 is still visible above the demarcation line 19. Such situations are illustrated in Figs. 2(a) to 2(c) that represent a friction body with 100%, 75% and 50%

respectively.

[0045] More advanced states of wear of the friction body 3 that require replacement of the brake pad 1 are shown in Figs. 2(d) to 2(e). Fig. 2(d) illustrates a brake pad 1 with a friction body 3 worn to 30% and where the edge 11 is at a position of the demarcation line 19. It can be observed that the first portion 15 has been worn away and is no longer visible (which may also be described as only the second portion 17 of the friction body 3 that is still visible). Therefore, the visual indicia 9 indicate that the brake pad 1 needs to be replaced. Fig. 2(e) illustrates a brake pad 1 with a friction body 3 worn to 20% and where the edge 11 is at a position that would be below the demarcation line 19 (which has been worn away). It can also be observed that the first portion 15 is no longer visible (i.e. only part of the second portion 17 of the friction body 3 is still visible) which may also prompt the user to replace the brake pad 1.

[0046] During inspection, a further consideration for the user may include determining if the edge 11 is at a regular distance (i.e. parallel) from the demarcation line 19 (or other visual indicia 9). If the distance is irregular, this may indicate uneven wear of the friction body 3, which may require corrective action to the brake pad 1 or other parts of the disc brake system 600.

[0047] The visual indicia 9 on the brake pad 1 may advantageously provide an objective indication of the state of wear of a brake pad 1. This may be in contrast with a user, such as a mechanic, visually inspecting the friction body 3 of the brake pad 1 and deciding, based on experience, if there is sufficient or insufficient material remaining on the friction body 3. Thus the brake pad 1, with the visual indicia may be more accurate and reliable, especially if the user is inexperience and/or fatigued.

[0048] Furthermore, the visual indicia 9 on the brake pad 1 may also assist users who may service multiple types and sizes of brakes. For example, a truck may have a brake pad 1 with a relatively thicker friction body 3, whereas a small passenger vehicle may have a brake pad with a relatively thinner friction body 3. Therefore, the threshold state of wear that requires

replacement of the brake pad 1, in terms of thickness of the remaining portions of the friction body 3 may be different. Thus the visual indicia 9 may allow quick determination of whether the brake pad 1 needs to be replaced. This is in contrast other methods, such as a user measuring the thickness of the friction body 3, and the referring to data sheets and specification for that particular brake pad 1 to determine if the thickness of the remaining portion of the friction body 3 is sufficient or insufficient such that the brake pad 1 should be replaced.

Variations of the visual indicia

[0049] The brake pad 1 of Figs. 1 and 2 illustrate an example of visual indicia 9 that may be used. Non-limiting examples of visual indicia will now be described.

[0050] Fig. 3(a) illustrates a brake pad 101 similar to the brake pad 1 described in Figs 1 and 2, where the visual indicia 9 includes printing a pattern 118 at the second portion 117. This pattern leaves the parts of the second portion 117 with the inherent colour of the friction body 3 and where the first portion 115 also has the same inherent colour. The pattern 118 may assist in providing visually distinctive indicia as well as identifying the brake pad 101.

[0051] Fig. 3(b) illustrates a brake pad 201 with visual indicia 9 that includes a line 219 on the sidewall 7 between a first portion 215 and a second portion 217. The line 219 is visually in contrast to the remaining first portion 215 and the second portion 217, both of which may be the same colour. The line 219 is at a position similar to the demarcation line 19 described in Figs. 1 and 2, and is also indicative of a state of wear such that the brake pad 201 should be replaced. Therefore when friction body 3 is worn such that edge 11 is visually observed to be at (or close to) the line 219, this is indicative that the brake pad 201 should be replaced. If the friction body 3 is in an advanced state of wear, such that the line 219 cannot be observed (because the line 219 has worn away), this could also be indicative that the brake pad 201 should be replaced.

[0052] The line 219 in Fig. 3(b) may be printed, etched or include other forms of visual markings on the sidewall 217. In one alternative, this may include applying one or more stickers to provide the line 219. The line 219, as illustrated in Fig. 3(b) is a broken line, and in other alternatives may include patterns. In some examples, having the visual indicia that is not monolithic may be advantageous in providing visually distinctive visual indicia. It may also aid in identifying that the brake pad 201 is of a type having visual indicia 9 compared to other types of brake pads.

[0053] Fig. 3(c) illustrates a brake pad 301 with visual indicia 9 that includes a plurality of visual markings to indicate respective states of wear of the friction body 3. In this example, the friction body 3 includes visual indicia 9 to distinguish three portions of the friction body. The first portion 315 represents the first 50% of the friction body that would be worn away. This is followed by an intermediate portion 316 that represents the subsequent 20% of the friction body that would be worn away. Finally, the second portion 317 represents the last 30% that would be worn away. Therefore during visual inspection, if the first portion 315, the intermediate portion 316, and the second portion 317 are visible, this indicates that there is between 50% to 100% of the friction body 3 remaining, and that the brake pad 301 is serviceable. If only the intermediate portion 316 and the second portion 317 is visible, this indicates that there is between 30% to 50% of the friction body 3 remaining and that the brake pad 301 is still serviceable but may need replacement in the future. If only the second portion 317 is visible, this indicates that there is 30% or less of the friction body 3 remaining and that the brake pad 301 should be replaced. [0054] Fig. 4 illustrates a brake pad 401 with visual indicia 9 that includes a plurality of lines 19, 29, and 39 that represents 30%, 50%, and 75% of the friction body 3 remaining. The visual indicia 9 also include characters 20, 30, 40 and 50 to provide textual information. Characters 50 include "100%" with corresponding arrows pointing towards the friction surface 5 (of an unused brake pad 401) indicate where the edge 11 would be for an unused brake pad 1. Characters 40 include "75%" with corresponding arrows pointing towards line 39 indicate where the edge 11 would be when 75% of the friction body 3 remains. Similarly characters 30 include "50%" with arrows to line 29 to indicate 50% of the friction body 3. Finally characters 20 include the textual information "replace" with corresponding arrows pointing to line 19 to indicate a threshold position for the edge 11. If upon visual inspection, the edge 11 is at or has retreated beyond line 19, this indicates that the brake pad 401 should be replaced.

[0055] An advantage of the characters, including textual information, is to provide additional information or easily recognisable information to the user. In Fig. 4, the characters 20, 30, 40 and 50 provide information to the user regarding the state of wear of the friction body 3 without the user necessarily being familiar with the markings, or marking conventions, of the particular brake pad 1.

[0056] Figs. 5(a) and (b) illustrate a brake pad 501 with visual indicia 9 that includes the sidewall 507 having one or more setbacks 61. These setbacks 61 are steps in the friction body 3 that may be visually identifiable even if the surface of the friction body 3 may be covered with brake dust, dirt, or other obscurants. These setbacks 61 may, in some circumstances, be identifiable by touch from the user. The user may determine the state of wear of the friction block 3 by visually identifying the edge 11 and the setbacks 61 in a manner similar to the other examples described above. It is to be appreciated that a combination of visual indicia 9 may be used, and as shown in Figs. 5(a), the brake pad 501 also includes characters 20, 30, 40, and 50 to provide additional information.

[0057] Figs. 7(a) and 7(b) illustrate another example of a brake pad 701 that includes a sidewall 7 with visual indicia 709. In this example the visual indicia 709 is in the form of a square dot matrix pattern printed to the sidewall 7. Also printed on the sidewall 7, adjacent to the square dot matrix pattern, is text 720. In this example, the text 720 is "REPLACE" to indicate that if the friction body 3 is worn such that edge 11 is at visual indicia 709, the brake pad 701 should be replaced. [0058] In one example, the square dot matrix pattern of the visual indicia 709 may be include a square approximately 3mm by 3mm. It is to be appreciated other sizes for the visual indicia 709 may be appropriate. For example, 4mm by 4mm, 5mm by 5mm.

[0059] In yet other examples the visual indicia may be a rectangle, circle, oval, triangle, etc. For example, the visual indicia may include a dot matrix pattern that in the form of rectangles, such as rectangular matrix 7 pixels by 9 pixels. In some particular examples, the rectangles are 2.33mm by 2.25 mm or 3mm by 1.75mm , but it is to be appreciated other dimensions and ratios may be used. The dot matrix pattern may be offset from the edges of the sidewall 7 to allows for minor variances between individual brake pads 701. This offset may be selected as appropriate and may, in some examples, be in the range of 0.7 mm to 1mm from the backing plate 13. It is to be appreciated that some examples may not include this offset and in others, the offset may be a different distance.

[0060] The brake pad 701 may also include other printed features, such as identification text 710. The identification text 710 may be used to indicate the type of part or brake pad 701 and may also include a serial number, batch number, model number etc.

[0061] The brake pad 701 also includes a pair of slots 12 that may function similar to the slots described above. The flanges 14 at opposite ends of the backing plate 13 include a bulbous portion to assist positioning and attachment to brake calipers. A shim 722 may be mounted to the backing plate 13. The shim 722 may include upwardly extending flanges 724 that extend across at least part of the sides of the backing plate 13. The shim 722 may assist in reducing vibration and therefore noise from the brakes during use.

Printing, painting, etching and stickers

[0062] Printing the visual indicia 9 may include using a heat resistant ink or toner. In one example, the ink may be white ink known as "79000-00106 Ink, white" for use with industrial ink jet printers produced by Paul Leibinger GmbH & Co. KG. In one example, printing at least part of the visual indicia in white may advantageously contrast with the dark inherent colour of the friction material of the friction body 3. It is to be appreciated other ink and printers may be suitable. [0063] The visual indicia 9 may include painting paint on the sidewall 7. This may include using a brush to paint at least part of the visual indicia 9 on the sidewall 7. In another example, this may include placing a stencil at the sidewall 7 and spraying paint onto the sidewall 7.

[0064] The visual indicia 9 may also include etching the friction body 3. This may include photochemical etching of the sidewall 7.

[0065] The visual indicia 9 may also include engraving the friction body 3. Engraving may include machine engraving with a graver to create lines, patterns, or other features that are visually perceivable to a user. The visual indicia may also include laser engraving of the sidewall 7 of the friction body 3.

[0066] The visual indicia 9 may also include stickers applied to the sidewall 3. This may include applying a film, with visual markings, onto the sidewall 3. An adhesive, such as a pressure sensitive adhesive, may assist in retaining the film to the sidewall 3. Desirably, the sticker includes heat resistant materials that can withstand the heat of normal use of the disc brake system.

Colouring agent

[0067] The visual indicia 9 may be provided by including a colouring agent in one or more parts of friction material in the friction body 3. For example, the friction material corresponding to the second portion 17 may include a colouring agent, and the colouring agent being visible as visual indicia 9 on the sidewall 7.

[0068] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.