A brake assembly comprising a composite backing plate and a method of manufacturing a composite backing plate

Abstract

Vehicle brake assemblies comprise friction pads attached to backing plates. It is desirable for backing plates to comprise composites including resol phenolic resin. However, composites comprising resol phenolic resins require treatment to remove or trap heat generated gases before use in brake assemblies, because such gases may cause thermal damage by inducing internal stresses. There is provided a composite a brake assembly comprising a friction pad attached to a composite backing plate 1, the composite backing plate 1 comprising resol phenolic resin, and a matrix of holes 15, wherein each hole extends at least partially through the composite backing plate 1. In this way, the composite comprising resol phenolic resin may be utilised in a brake assembly without the need for treatment to actively remove or trap the heat generated gases.

Description

A BRAKE ASSEMBLY COMPRISING A COMPOSITE BACKING PLATE AND A METHOD OF MANUFACTURING A COMPOSITE BACKING PLATE

[0001] The present invention relates generally to a composite backing plate, and a method of forming a composite backing plate, and finds particular, although not exclusive, utility in a brake assembly comprising a backing plate for a friction pad.

[0002] Vehicle brake systems comprise friction pads attached to backing plates. The action of braking may cause a high temperature environment within the brake system. As such, the backing plate needs to withstand high temperatures, in particular, temperatures exceeding 200 degrees Celsius.

[0003] The use of resol phenolic resins to form composite backing plates is desirable because they have a liquid form before they set, and therefore may have an increased versatility compared to other phenolic resins.

[0004] However, the thermal stability of resol phenolic resin is relatively low, and may only withstand temperatures up to 200 degrees Celsius. As a result, thermal damage including delamination, blistering, or edge cracking may result when using resol phenolic resin in environments above 200 degrees Celsius. This damage may develop as a result of internal stresses caused by gases generated from within the material when the component is heated, which become trapped within the composite and exert internal pressure.

[0005] To use composites comprising resol phenolic resin in temperatures exceeding 200 degrees Celsius, the thermoset composite may first be treated to remove the gases generated by heating. Removing the gases may be achieved by treating the composite in an autoclave. Research has also been carried out regarding alternatively trapping the gases within the composite in such a way as to prevent them from expanding and causing delamination. This research has included treatment within a hydroclave to change the chemical structure of the composite to prevent small gas molecules from diffusing out. Both treatments are time and energy consuming, and relatively expensive.

[0006] Thermal damage is particularly a problem in “thick section” composites, which may include composites having a thickness of at least 4mm.

[0007] It is therefore desirable to provide brake assembly components comprising resol phenolic resin that are resistant to thermal damage without the need for treatment using autoclaves or hydroclaves to actively remove or trap the heat generated gases after the composite has been thermoset.

[0008] In a first aspect, the present invention provides a brake assembly comprising a friction pad attached to a composite backing plate, the composite backing plate comprising resol phenolic resin, and a matrix of holes, wherein each hole extends at least partially through the composite backing plate.

[0009] In this way, a composite brake pad comprising resol phenolic resin that has not been treated to actively remove or trap the gases generated from heating the resol phenolic resin may still be used within an environment exceeding 200 degrees Celsius, without succumbing to thermal damage including delamination, blistering, and / or edge cracking. This is because the matrix of holes may provide diffusion paths within the backing plate sufficient to allow gases produced from heating to escape, rather than exerting internal pressures.

[0010] Moreover, because the composite backing plate may be produced simply, without the need for treating in expensive and specific tools such as autoclaves or hydroclaves, manufacturing costs may be reduced. The composite backing plates may also be produced quickly, without the need of time-consuming processes comprising a large number of separate treatment steps.

[0011] The composite backing plate may comprise fibres, and the phenolic resin may bind the fibres together. In this way, the composite backing plate may be a fibre reinforced composite.

[0012] The resol phenolic resin of the composite backing plate may not have been actively treated to remove gases inherent within it. The resol phenolic resin of the composite backing plate may not have been actively treated by use of an autoclave to remove gases inherent within it. In this way, the composite backing plate may comprise resol phenolic resin that has not been actively heated to generate gases, and subsequently had those gases actively removed. The term “active” may mean taking steps to treat the resin so as to manage the gases, as opposed to merely leaving it at room temperature / pressure and waiting for any gases to dissipate.

[0013] The resol phenolic resin of the composite backing plate may not have been actively treated to trap gases inherent within it. The resol phenolic resin of the composite backing plate may not have been actively treated by use of a hydroclave to trap gases inherent within it, such that in use when the working temperature rises beyond 200 degrees Celsius any inherently present gases are prevented from expanding and causing delamination.

[0014] The composite backing plate may comprise an approximate rectangular shape. The length of the composite backing plate may be 20mm to 300mm. The width of the composite backing plate may be 10mm to 200mm. Other shapes of the composite backing plate are also contemplated, such that the composite backing plate may be arrangeable within a brake system. For example, the composite backing plate may have a comma-like shape.

[0015] The backing plate may have a thickness of at least 4mm. Other thicknesses are also contemplated. For example, the composite backing plate may have a thickness of at least 5mm, at least 6mm, at least 7mm, at least 8mm, at least 9mm, or at least 10mm. The thickness of the composite backing plate may vary along its length.

[0016] The centre of each hole may be between 20mm and 35mm from the centre of any adjacent hole. In this way, the matrix of holes may provide an optimal number and / or spacing of holes to provide sufficient additional surfaces to allow produced gases to escape, without significantly affecting the mechanical properties of the composite backing plate. However, other distances between the centres of any two adjacent holes are also contemplated. For example, the centre of each hole may be between 15mm and 50mm from the centre of any adjacent hole.

[0017] Alternatively, the edge of each hole may be between 20mm and 35mm from the centre of any adjacent hole. However, other distances between the edges of any two adjacent holes are also contemplated. For example, the edge of each hole may be between 15mm and 50mm from the edge of any adjacent hole.

[0018] Each of the holes may have a width between 0.5mm and 4mm, in a direction perpendicular to the direction in which the hole extends. Other widths are also contemplated, for example, each hole may have a width between 4mm and 10mm. Each hole may have a different width relative to the other holes.

[0019] Each hole may have a circular cross-section. The circular cross-section may be in a direction perpendicular to the direction in which the hole extends. Other cross-sectional shapes are also contemplated, for example, the cross-section may be an oval, triangular, square, or hexagonal. Each hole may have a different shaped cross-section relative to the other holes.

[0020] The holes may be, or act as, gas vents. In use, the gas vents may direct gases, produced internally within the backing plate when heated, in use, out of the backing plate.

[0021] The matrix of holes may comprise an array of holes. Each hole in the array may extend at least partially through the composite backing plate.

[0022] Each hole extending “partially” through the composite backing plate may comprise the hole terminating within the composite backing plate. Alternatively, holes may extend completely through the composite backing plate (i.e., not “partially”). In this way, each hole of the matrix of holes may comprise a subset of holes extending completely through the composite backing plate, and a subset of holes each terminating within the composite backing plate. The holes terminating within the composite backing plate may terminate at different depths within the composite backing plate to each other.

[0023] At least one of the holes may have a depth of between 30% and 90% of the thickness of the backing plate.

[0024] At least a portion of the matrix of holes may comprise a non-uniform pattern of holes relative to each other. For example, the distances between each hole, and / or their locations relative to each other, may vary throughout the portion of the matrix of holes. In this way, the optimum number of holes may be arranged on the composite backing plate relative to the shape and / or size of the composite backing plate.

[0025] At least a portion of the matrix of holes may comprise a uniform pattern of holes relative to each other. For example, the distances between each hole, and / or their locations relative to each other, may be consistent throughout the portion of the matrix of holes.

[0026] The composite backing plate comprises a first face, and a second face arranged opposite to the first face, and the matrix of holes may be arranged to extend into the first face and / or the second face. In this way, a hole extending completely through the composite backing plate may extend from the first face to the second face. A hole extending only partially through the composite backing plate may extend from either the first face or the second face, and terminate within the composite backing plate.

[0027] At least one of the holes may be arranged perpendicularly relative to the plane of the first face. At least one of the holes may be arranged perpendicularly relative to the plane of the second face. At least one hole may be arranged at an acute angle relative to the plane of the first face. At least one hole may be arranged at an acute angle relative to the plane of the second face. The matrix of holes may comprise a subset of holes arranged perpendicularly relative to the plane of the first face or second face, and a subset of holes arranged at an acute angle relative to the plane of the first face or second face.

[0028] The composite backing plate may comprise a plurality of first holes arranged to extend from the first face and terminate within the composite backing plate, and a plurality of second holes arranged to extend from the second face and terminate within the composite backing plate, wherein the first and second holes may be arranged alternately adjacent one another. In this way, any gases, produced in use by heating, may be evenly diffused from the first and second faces of the composite backing plate.

[0029] The holes may be formed within the composite backing plate by hand using common workshop equipment such as drills. Alternatively, the holes may be formed within the composite backing plate using equipment such as laser cutters or water jets. Such equipment may be controlled via Computer Numerical Control (CNC).

[0030] In a second aspect, the invention provides a method of manufacturing a composite backing plate for a friction pad, the method comprising the steps of: forming a backing plate from a composite comprising resol phenolic resin such that it is in a state where gases generated during heating, in subsequent use, have not been removed or trapped through active treatment; and forming a matrix of holes within the composite.

[0031] In this way, the method produces a backing plate for a friction pad that may not require active treatment to remove gases generated by heating prior to the use of the backing plate in a brake assembly. As such, because the method may not require the use of expensive and specific tools such as autoclaves or hydroclaves, manufacturing costs may be reduced. The method may also produce composite backing plates more quickly, without the need for time-consuming processes comprising a large number of separate treatment steps.

[0032] Active treatment may comprise the treatment of the composite in an autoclave to remove the gases generated from heating the phenolic resin, such that they do not form during subsequent heating, in use. Active treatment may comprise the treatment of the composite in a hydroclave to trap the gases which may be subsequently generated by heating the phenolic resin such that they do not expand within the composite and cause delamination during subsequent heating, in use.

[0033] The matrix of holes may be formed by drilling, laser cutting, or by the use of high-pressure water jets. Forming the matrix of holes may be controlled via Computer Numerical Control (CNC).

[0034] The method may comprise the step of affixing a friction pad to the backing plate to form a brake assembly.

[0035] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.

[0036] is a perspective view of a composite backing plate.

[0037] is a plan view of the composite backing plate of.

[0038] is a cross-sectional view of the composite backing plate of, taken along the line A-A.

[0039] is a perspective view of another composite backing plate.

[0040] is a plan view of the composite backing plate of.

[0041] is a cross-sectional view of the composite backing plate of, taken along the line B-B.

[0042] is a perspective view of a further composite backing plate.

[0043] The present invention will be described with respect to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. Each drawing may not include all of the features of the invention and therefore should not necessarily be considered to be an embodiment of the invention. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[0044] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other sequences than described or illustrated herein. Likewise, method steps described or claimed in a particular sequence may be understood to operate in a different sequence.

[0045] Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other orientations than described or illustrated herein.

[0046] It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0047] Reference throughout this specification to “an embodiment” or “an aspect” means that a particular feature, structure or characteristic described in connection with the embodiment or aspect is included in at least one embodiment or aspect of the present invention. Thus, appearances of the phrases “in one embodiment”, “in an embodiment”, or “in an aspect” in various places throughout this specification are not necessarily all referring to the same embodiment or aspect, but may refer to different embodiments or aspects. Furthermore, the particular features, structures or characteristics of any one embodiment or aspect of the invention may be combined in any suitable manner with any other particular feature, structure or characteristic of another embodiment or aspect of the invention, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments or aspects.

[0048] Similarly, it should be appreciated that in the description various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Moreover, the description of any individual drawing or aspect should not necessarily be considered to be an embodiment of the invention. Rather, as the following claims reflect, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

[0049] Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0050] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0051] In the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value.

[0052] The use of the term “at least one” may mean only one in certain circumstances. The use of the term “any” may mean “all” and / or “each” in certain circumstances.

[0053] The principles of the invention will now be described by a detailed description of at least one drawing relating to exemplary features. It is clear that other arrangements can be configured according to the knowledge of persons skilled in the art without departing from the underlying concept or technical teaching, the invention being limited only by the terms of the appended claims.

[0054] Figures 1a to 1c show a composite backing plate 1. The composite backing plate 1 is formed of a composite comprising resol phenolic resin.shows a perspective view of the composite backing plate 1. The composite backing plate 1 is shown to be a cuboidal plate comprising a substantially planar first face 3, and a substantially planar second face 5 located opposite to the first face 3. The thickness of the composite backing plate 1 may be 4mm, although other thicknesses are also contemplated. In use, a friction pad is attached to the first face 3 or the second face 5. However, for the sake of clarity, the friction pad is not shown. The friction pad may be attached to the first face 3 or second face 5 via adhesive, and / or a mechanical fixing such as a connection having an interference fit, or an interlocking connection. Other methods are contemplated.

[0055] Sides 7, 9, 11, 13 extend between the first face 3 and the second face 5.

[0056] Holes 15 are shown to extend into the composite backing plate 1 from the first face 3. There are fifteen holes 15, arranged in a uniform pattern of three rows of five holes. The pattern of fifteen holes is a “matrix of holes”. The matrix of holes is shown to substantially cover the entire first face 3, as opposed to covering only a portion of the first face 3.

[0057] is a plan view of the composite backing plate 1. Each hole 15 is equal to, or less than, 35mm from an adjacent hole 15.

[0058] is a cross-sectional view of the composite backing plate of, taken along the line A-A. Each hole 15 is shown to extend from the first face 3, to the second face 5, such that they extend completely through the composite backing plate 1. All but one of the holes 15 are also shown to extend in a direction perpendicular to the plane in which the first face 3 lies. Hole 15a is shown to extend at an acute angle relative to the plane in which the first face 3 lies.

[0059] Figures 2a to 2c show a composite backing plate 101. The composite backing plate 101 is formed of a composite comprising resol phenolic resin.

[0060] is a perspective view of a composite backing plate 101. The composite plate 101 comprises a substantially planar first face 103, a substantially planar second face 105 opposite to the first face 103, and sides 107, 109, 111, 113 extending between the first face 103 and the second face 105. The thickness of the composite backing plate 101 may be 2mm, although other thicknesses are also contemplated. In use, a friction pad is attached to the first face 103 or the second face 105 such that the complete unit may be used as a vehicle brake pad. However, for the sake of clarity, the friction pad is not shown. The friction pad may be attached to the first face 103 or second face 105 via adhesive, and / or a mechanical fixing such as a connection having an interference fit, or an interlocking connection.

[0061] A matrix of holes is shown by a plurality of first holes 115 extending into the composite backing plate 101 from the first face 103, and a plurality of second holes 117. The second holes 117 extend into the composite backing plate 101 from the second face 105, and therefore the points at which they would extend into the first face 103 are indicated inby dashed circular lines. The plurality of first and second holes 115, 117 are arranged in a uniform pattern of three rows of five holes, wherein the first and second holes 115, 117 are arranged alternately adjacent one another.

[0062] In this way, eight first holes 115 extend from the first face 103, and are shown to be arranged in a uniform pattern of a row of three holes, a second row of two holes, and a third row of three holes, wherein the second row is offset relative to the first and second rows. Seven second holes 117 extend from the second face 105, and are shown to be arranged in a uniform pattern of a row of two holes, a second row of three holes, and a third row of two holes. It will be appreciated that this is a different matrix of holes to that shown in Figures 1a to 1c, because holes extend into both the first face 103 and second face 105.

[0063] is a plan view of the composite backing plate of. Each first hole and / or second hole 115, 117 is equal to, or less than, 35mm from an adjacent first hole and / or second hole 115, 117.

[0064] is a cross-sectional view of the composite backing plate of, taken along the line B-B. The first holes 115 are shown to extend from the first face 103 and terminate within the composite backing plate 101. A such, they do not extend completely through the composite backing plate 101 to the second face 105. The second holes 117 are shown to extend from the second face 105 and terminate within the composite backing plate 101. As such, they do not extend completely through the composite backing plate 101 to the first face 103. The first and second holes 115, 117 are shown to be arranged alternately adjacent one another. The first and second holes 115, 117 are shown to extend approximately three quarters of the distance between the first face 103 and second face 105. However, other proportions are also contemplated, such as a quarter, or half the distance between the first face 103 and second face 105. The distance may also be determined as a quantifiable distance. For example, the first and second holes 115, 117 may extend between 1.2mm and 3.6mm into the composite backing plate 101.

[0065] is a perspective view of a composite backing plate 201. The composite backing plate 201 is formed of a composite comprising resol phenolic resin. The composite backing plate 201 is shown to have a curved shape. This shape may be more compatible with typical brake systems. The composite plate 201 comprises a substantially planar first face 203, a substantially planar second face 205 opposite to the first face 203. The thickness of the composite backing 201 may be 4mm, although other thicknesses are also contemplated. In use, a friction pad is attached to the first face 203 or the second face 205. However, for the sake of clarity, the friction pad is not shown. The friction pad may be attached to the first face 203 or second face 205 via adhesive, or and / or a mechanical fixing such as a connection having an interference fit, or an interlocking connection.

[0066] A matrix of holes 215 is shown to extend into the composite backing plate 201 from the first face 203. Although not shown, the matrix of holes may also, or alternatively, include holes extending into the composite backing plate 201 from the second face 205.

[0067] In use, the composite backing plates 1, 101, 201 may be utilised in brake systems to withstand thermal damage by providing additional surfaces from which gases produced through heating may escape. In this way, the composite backing plates 1, 101, 201 may not require expensive and time-consuming treatment to remove or trap heat generated gases before being utilised in a brake system.

Claims

A brake assembly comprising a friction pad attached to a composite backing plate, the composite backing plate comprising resol phenolic resin, and a matrix of holes, wherein each hole extends at least partially through the composite backing plate.The brake assembly of claim 1, wherein the centre of each of the holes is between 20mm and 35mm from the centre of any adjacent hole.The brake assembly of any preceding claim, wherein the composite backing plate has a thickness of at least 4mm.The brake assembly of any preceding claim, wherein at least a portion of the matrix of holes comprises a non-uniform pattern of holes relative to each other.The brake assembly of any preceding claim, wherein at least a portion of the matrix of holes comprises a uniform pattern of holes relative to each other.The brake assembly of any preceding claim, wherein the composite backing plate comprises a first face, and a second face arranged opposite to the first face, and the matrix of holes is arranged to extend into the first face and / or the second face.The brake assembly of claim 6, wherein at least one of the holes is arranged perpendicularly relative to the first face or second face.The brake assembly of either of claim 6 and claim 7, wherein at least one of the holes is arranged at an acute angle relative to the first face or second face.The brake assembly of any of claims 6 to 8, comprising a plurality of first holes arranged to extend from the first face and terminate within the composite backing plate, and a plurality of second holes arranged to extend from the second face and terminate within the composite backing plate, wherein the first and second holes are arranged alternately adjacent one another.The brake assembly of any preceding claim, wherein each of the holes has a width between 0.5mm and 4mm, in a direction perpendicular to the direction in which the hole extends.The brake assembly of any preceding claim, wherein each hole has a circular cross-section.The brake assembly of any preceding claim, wherein at least one of the holes has a depth of between 30% and 90% of the thickness of the backing plate.The brake assembly of any preceding claim, wherein the resol phenolic resin of the composite backing plate has not been actively treated to remove gases inherent within it.The brake assembly of claim 13, wherein the resol phenolic resin of the composite backing plate has not been actively treated by use of an autoclave to remove gases inherent within it.The brake assembly of any preceding claim, wherein the resol phenolic resin of the composite backing plate has not been actively treated to trap gases inherent within it.The brake assembly of any preceding claim, wherein the resol phenolic resin of the composite backing plate has not been actively treated by use of a hydroclave to trap gases inherent within it.A method of manufacturing a composite backing plate for a friction pad, the method comprising the steps of: forming a backing plate from a composite comprising resol phenolic resin such that it is in a state where gases generated during heating, in subsequent use, have not been removed or trapped through active treatment; and forming a matrix of holes within the composite backing plate, wherein each hole is configured to be a gas vent for directing gases, produced internally within the backing plate when heated, in use, out of the backing plate.

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