Non-woven, fracture reducing brake rotor preforms and pads

The present disclosure describes brake rotor preforms and brake pads configured to reduce fracturing and failure of brake rotors by distributing the axial force applied during braking across butt joints between abutting segments of preforms and rotors manufactured therefrom. The preforms comprise a spiral annular structure formed about a longitudinal axis from a plurality of carbon fiber precursor tow segments having a partial annular shape. Each segment is asymmetrical when viewed in the longitudinal axis direction and configured so planes defined by the segment's ends are never coplanar with planes extending radially from the longitudinal axis. The brake pads have a partial annular shape and ends adapted to prevent planes defined by the ends from being coplanar during use with a plane extending radially from a brake rotor longitudinal axis.

FIELD OF THE INVENTION

The present invention relates, generally, to the field of brake friction components, including, but not limited to, brake rotor preforms, brake rotors, brake pads, and methods for manufacturing the same.

BACKGROUND OF THE INVENTION

Brake rotors for some vehicles are manufactured by initially forming brake rotor preforms10(also sometimes referred to herein as “preforms”) that are subsequently machined to produce the brake rotors. The brake rotor preforms10(and, hence, the brake rotors) are formed from a plurality of segments12comprising carbon fiber precursor that are laid and abutted end-to-end about a central longitudinal axis14to form an annular spiral structure16. The spiral structure16has a plurality of flights18(seeFIG. 1in which a single flight18is illustrated) similar to those of screw thread, but different from a screw thread in that each successive flight18lies longitudinally adjacent to and in contact with a previous flight18such that the flights18are in contact with one another in the longitudinal direction. Each flight18comprises multiple segments12with each segment12having a partial annular shape such that each segment12comprises a sector of an annulus. As more clearly seen inFIGS. 2 and 3, each segment12also has an inner radius, RI, an outer radius, RO, an included central angle, β, about longitudinal axis14, a first end20, and a second end22. Referring back toFIG. 1, the spiral structure16also has a plurality of radially-extending butt joints24, with each butt joint24being formed between abutting ends20,22of respectively adjacent segments12. The central angle, β, of each segment12is generally selected to determine the number of segments12per flight18of the spiral structure16and is selected so that the butt joints24between segments12of a flight18are not coplanar with the butt joints24between segments12of a longitudinally adjacent flight18. The segments12of a particular flight18typically comprise carbon fiber precursor tow oriented in either a chordal direction (seeFIG. 2) or in a radial direction (seeFIGS. 3 and 4). Generally, the segments12of adjacent flights18do not include carbon fiber precursor tow oriented in the same direction in order to improve the mechanical and structural properties of the brake rotor preform10.

The above described preform architecture has been successfully used for brake rotors employed in the aerospace industry where there are, typically, at least two rotors and three stators in a brake stack and axial compression of the stack is used to create and control friction to provide braking. More recently, preforms10having such architecture have been used in brake applications having a single carbon-carbon brake rotor disk30(also sometimes referred to herein as a “brake rotor30”) machined from a preform10to have opposed front and back friction surfaces32. Braking friction is generated by applying axial force (a force applied in the longitudinal direction of the brake rotor) on only the portions of the brake rotor's friction surfaces32which are present between two brake pads34(seeFIG. 5in which only one friction surface32and one brake pad34are visible) held by a caliper. Similar to the segments12of the brake rotor preform10from which the brake rotor30was machined, each brake pad34has a partial annular shape with a first end36and a second end38. In such brake applications, the brake pads34often do not compress the friction surfaces32of the brake rotor30uniformly at all times. When compressed with the brake rotor30turning between brake pads34, the compression is sometimes uneven in the axial direction, causing a shear force within the carbon-carbon brake rotor30. When the butt joints24between adjacent segments12of the flights18of the brake rotor preform10(and, hence, of the brake rotor30) rotate about central longitudinal axis14(for example, in the rotational direction40) past an end36,38of the brake pad34, the butt joints24are radially aligned momentarily at different times in a radially extending plane42,44with either the first end36(seeFIG. 6) or second end38(seeFIG. 7) of the brake pad34and the shear force causes the carbon-carbon composite of the brake rotor preform10(and, hence, of the brake rotor30) to fracture at or near the butt joints24between adjacent segments12. These fractures then typically propagate through the carbon-carbon composite and cause the entire brake rotor30to fail.

There is, therefore, a need in the industry for brake rotor preforms, brake rotors, and/or brake pads having configurations and architectures that solve these and other problems, deficiencies, and shortcomings of the present configurations and architectures.

SUMMARY OF THE INVENTION

Broadly described, the present invention comprises brake friction components that reduce fracturing and failure of brake rotors, together with methods for manufacturing brake friction components. According to example embodiments described herein, such brake friction components include, without limitation, brake rotor preforms, brake rotors machined or otherwise manufactured from brake rotor preforms, and brake pads operable with brake rotors to provide braking. The brake rotor preforms of the example embodiments comprise a spiral annular structure formed about a central longitudinal axis from a plurality of segments having a partial annular shape. Each segment is asymmetrical when viewed in the direction of the central longitudinal axis and is configured such that planes defined, respectively, by each of the segment's ends are not coplanar with planes extending through and radially from the central longitudinal axis. The segments are arranged end-to-end in a series of longitudinally adjacent flights, with a butt joint being formed between ends of abutted segments and with each flight generally including segments of carbon fiber precursor tow oriented in the same direction. Longitudinally adjacent flights may include segments of carbon fiber precursor tow oriented in different directions in order to make the preform's mechanical and structural properties more directionally independent, or may alternatively include segments of carbon fiber precursor tow oriented in a single direction to cause the preform's mechanical and structural properties to be directionally dependent or to add additional strength at the butt joints between abutted segments. The carbon fiber precursor tow may, for example, be oriented in chordal or radial directions, or be oriented at a positive or negative angle relative to the chordal direction. The segments are continuously needled in the longitudinal direction during the preform's manufacture to join the longitudinally adjacent segments of different flights together, thereby improving the preform's mechanical and structural properties and reducing the risk of separation or delamination of the preform's flights from one another.

In accordance with other example embodiments described herein, brake pads are configured with a generally arcuate or partial annular shape about and relative to a longitudinal axis. The brake pads have ends formed such that planes defined, respectively, by each of a pad's ends are not coplanar with planes extending through and radially from a central longitudinal axis of a brake rotor with which the brake pads are used. In one embodiment, the brake pad's ends lie entirely within respective planes that are oriented at angles relative to planes extending through and radially from a central longitudinal axis of a brake rotor. In other embodiments, the brake pad's ends have a wave-like or sawtooth-like shape such that each of the pad's ends do not lie entirely within a single plane.

Advantageously, the brake rotor preforms of the example embodiments reduce fractures and failures at the butt joints between abutted segments by, among other things, preventing a butt joint from aligning coplanarly with an end of a brake pad when axial force is applied during braking by the brake pad to a brake rotor made from a brake rotor preform described herein. When such a brake rotor rotates relative to a conventional brake pad having radially extending ends, a plane defined by an end of the brake pad intersects a plane defined by a butt joint between abutting rotor segments. Initially, at the instant time when the planes begin to intersect, material from only one of the adjacent segments is present on both sides of the plane defined by the brake pad's end. Then, as the brake rotor continues to rotate relative to the brake pad and the planes continue to intersect while an axial force is applied by the brake pad to the brake rotor, material from each abutting segment is present on both sides of the plane defined by the brake pad's end. As the brake rotor rotates further relative to the brake pad, the plane defined by the end of the brake pad no longer intersects with the plane defined by the butt joint between abutting rotor segments, at which time there is again material from only one segment (in this case, from the other segment of the abutting segments) on both sides of the brake pad's end. By virtue of the brake preform's (and, hence, the brake rotor's) configuration, the axial force applied by the brake pad during an encounter of a pad end with a butt joint between abutting segments is distributed incrementally and gradually across the butt joint and to portions of both abutting segments instead of being applied solely to a single segment located on one side of a butt joint as is the case during an encounter between a pad end of a prior art brake pad and a butt joint of a prior art brake rotor manufactured from a prior art brake rotor preform. Because the axial force is not applied solely to a single segment during such encounter, there is less tendency for the abutting segments to shear relative to one another and, consequently, for a fracture to develop at the butt joint that may result in failure of the entire brake rotor.

Also advantageously, the brake pads of the example embodiments reduce fractures and failures at butt joints between adjacent segments of conventional brake rotors manufactured from conventional brake preforms. In a manner similar to that of the brake rotor preforms of the example embodiments, the brake pads (instead of the brake rotor preform and brake rotor) are configured to prevent a butt joint of a conventional brake rotor from aligning coplanarly with an end of the brake pad when axial force is applied during braking by the brake pad to the brake rotor. Due to such configuration and as similarly described above, the axial force applied by the brake pad during an encounter of a pad end with a butt joint between abutting segments is distributed across the butt joint and to portions of both abutting segments instead of being applied solely to a single segment located on one side of a butt joint as is the case during an encounter between a pad end of a prior art brake pad and a butt joint of a prior art brake rotor manufactured from a prior art brake rotor preform. By virtue of the axial force being applied to segments on both sides of the butt joint during such encounter, the abutting segments are less prone to shear relative to one another and, hence, there is a reduced possibility of a fracture developing at the butt joint that may, ultimately, cause the entire brake rotor to fail.

Other uses, advantages and benefits of the present invention may become apparent upon reading and understanding the present specification when taken in conjunction with the appended drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in which like numerals represent like elements or steps throughout the several views,FIG. 8displays a schematic, side elevational view of a brake rotor preform100having a new architecture in accordance with a first example embodiment of the present invention. The brake rotor preform100comprises a plurality of flights102(seeFIGS. 9 and 11) of multiple segments104(seeFIGS. 10 and 12) arranged about a longitudinal central axis106in an annular spiral structure108having an inner radius, RI, and an outer radius, RO, relative to the longitudinal central axis106. The flights102of the annular spiral structure108are similar to those of screw thread, but different from a screw thread in that each successive flight102lies longitudinally adjacent to and in contact with a previous flight102such that the flights102are in contact with one another in the longitudinal direction. The flights102of the annular spiral structure108include a plurality of first flights102A having carbon fiber precursor tow oriented in a chordal direction and a plurality of second flights102B having carbon fiber precursor tow oriented in a radial direction. The first flights102A and second flights102B are generally arranged in an alternating configuration such that a second flight102B is longitudinally present between two successive first flights102A. Through use of this alternating configuration instead of a configuration having all carbon fiber precursor tow oriented in a single direction or a configuration having longitudinally adjacent flights with the same carbon fiber tow orientation grouped together, the mechanical and structural properties of the preform100are improved and made more uniform and symmetrical in all directions. It should, however, be appreciated and understood that in other example embodiments (including other example embodiments described herein), the preform100may include flights102having carbon fiber precursor tow oriented in directions other than the chordal and radial directions, may include flights102having carbon fiber precursor oriented in a lesser or greater number of directions, and may include flights102arranged in a configuration other than an alternating configuration.

FIG. 9displays a schematic, longitudinal view of a first flight102A of brake rotor preform100in accordance with the first example embodiment of the present invention. The first flight102A comprises a plurality of segments104A manufactured from carbon fiber precursor tow114oriented in a chordal direction. Each segment104A comprises a sector of an annulus and has a first end116and a second end118. The segments104A are laid end-to-end about the longitudinal central axis106and form butt joints120at the abutting ends116,118of two adjacent segments104A. However, unlike prior art preforms, the butt joints120and ends116,118are not aligned with a radius of the preform100and do not extend in a radial direction.

An individual segment104A of the first flight102A brake rotor preform100, according to the first example embodiment of the present invention, is illustrated in the schematic, longitudinal view ofFIG. 10. The segment104A comprises, as described above, carbon fiber precursor tow114oriented in a chordal direction and has an asymmetric shape when viewed in a longitudinal direction. As illustrated inFIG. 10, the segment104A has an inner edge122formed at the preform's inner radius, RI, and an outer edge124formed at the preform's outer radius, RO, that is radially disposed relative to the inner edge122. The segment's first and second ends116,118extend between the segment's inner and outer edges122,124that have respective lengths, L1and L2, between the segment's inner and outer edges122,124. The segment's first end116defines an angle, θ1, relative to a tangent126of the segment's outer edge124at the location where the segment's outer edge124and first end116intersect. The segment's second end118defines an angle, θ2, relative to a tangent128of the segment's inner edge122at the location where the segment's inner edge122and second end118intersect. According to the first example embodiment, the angular measures of angles θ1and θ2are equal and the lengths L1and L2of first and second ends116,118are also equal. The particular angular measures for angles θ1and θ2and the particular lengths L1and L2of first and second ends116,118depend on the particular embodiment of the preform100and its dimensions in such embodiment.

FIG. 11displays a schematic, longitudinal view of a second flight102B of brake rotor preform100in accordance with the first example embodiment of the present invention. The second flight102B comprises a plurality of segments104B manufactured from carbon fiber precursor tow130oriented in a radial direction. Each segment104B comprises a sector of an annulus and has a first end132and a second end134. The segments104B are laid end-to-end about the longitudinal central axis106and form butt joints136at the abutting ends132,134of two adjacent segments104B. However, similar to the segments104A of the first flight102A and unlike prior art preforms, the butt joints136and ends132,134are not aligned with a radius of the preform100and do not extend in a radial direction.

An individual segment104B of the second flight102B brake rotor preform100, according to the first example embodiment of the present invention, is illustrated in the schematic, longitudinal view ofFIG. 12. The segment104B comprises, as described above, carbon fiber precursor tow130oriented in a radial direction and has an asymmetric shape when viewed in a longitudinal direction. As illustrated inFIG. 12, the segment104B has an inner edge138formed at the preform's inner radius, RI, and an outer edge140formed at the preform's outer radius, RO, that is radially disposed relative to the inner edge138. The segment's first and second ends132,134extend between the segment's inner and outer edges138,140that have respective lengths, L3and L4, between the segment's inner and outer edges138,140. The segment's first end132defines an angle, θ3, relative to a tangent142of the segment's outer edge140at the location where the segment's outer edge140and first end132intersect. The segment's second end134defines an angle, θ4, relative to a tangent144of the segment's inner edge138at the location where the segment's inner edge138and second end134intersect. According to the first example embodiment, the angular measures of angles θ3and θ4are equal and the lengths L3and L4of first and second ends132,134are also equal. The particular angular measures for angles θ3and θ4and the particular lengths L3and L4of first and second ends132,134depend on the particular embodiment of the preform100and its dimensions in such embodiment. Also according to the first example embodiment, the angular measures of angles θ3and θ4are equal to the angular measures of angles θ1and θ2of segments104A and the lengths L3and L4of first and second ends132,134are equal to the lengths L1and L2of the first and second ends116,118of segments104A.

The preform100of the first example embodiment is, typically, manufactured through use of machine which places segments104A about longitudinal axis106in an end-to-end manner to form a first flight102A of the preform's annular spiral structure108. Once the first flight102A is complete, segments104B are placed about longitudinal axis106in an end-to-end manner to form a second flight102B of the preform's annular spiral structure108. The placement of segments104A,104B about longitudinal axis106is repeated to form additional first and second flights102A,102B of the preform's annular spiral structure108such that second flights102B are alternatingly included between successive first flights102A. As segments104A,104B are positioned and flights102A,102B are formed, the segments104A,104B and carbon fiber precursor tow114,130thereof are needled together to couple the segments104A,104B and flights102A,102B together in the preform's longitudinal direction to create the preform's annular spiral structure108. After the segments104A,104B and flights102A,102B have been respectively formed and needled together, the preform100is carbonized to change the carbon fiber precursor into carbon fiber and then a carbon matrix is subsequently added to the preform100. Finally, the preform100is machined to produce a brake rotor150having the underlying annular spiral structure108of the preform100. Generally, such machining produces a brake rotor150having at least one friction surface152.

In use on a vehicle, the brake rotor150rotates in tandem with a wheel of the vehicle with vehicle braking being accomplished by the application of an axial force causing a brake pad154held by a caliper to engage the brake rotor's friction surface152.FIG. 13displays a schematic representation of the relationship between the brake rotor150(and the butt joints120,136of the brake rotor150and underlying preform100) and brake pad154during rotation of the brake rotor150about longitudinal axis106in rotational direction156. InFIG. 13, only segments104A of a first flight102A of the brake rotor150and underlying preform100are shown in relation to the brake pad154, but it should be appreciated and understood that a similar relationship exists between segments104B of a second flight102B of the brake rotor150, underlying preform100, and brake pad154.

As the brake rotor150rotates during vehicle braking, the brake rotor150rotates in the rotational direction156with the butt joints120of the brake rotor150(and underlying brake rotor preform100) passing under the first and second ends158,160of the brake pad154. However, unlike prior art brake rotors and preforms, the butt joints120are never radially aligned with either the first end158or second end160of the brake pad154. More particularly and as seen inFIGS. 14 and 15, planes162defined by the butt joints120are never coplanar during braking with planes164,166defined, respectively, by the first and second ends158,160of the brake pad154and central longitudinal axis106. To clarify, planes164,166extend radially from central longitudinal axis106with central longitudinal axis106lying within each plane164,166. Furthermore and also during vehicle braking, planes162associated, respectively, with each butt joint120intersect planes164,166corresponding to the brake pad's first and second ends158,160at only a single location as the butt joints120pass under the brake pad's first and second ends164,166. As a consequence, axial forces exerted on the brake rotor150by the brake pad154are never applied entirely at the butt joints120and are, instead, distributed across the butt joints120between two abutting segments104A with the result being reduced fracturing and failure of the brake rotor150and underlying brake rotor preform100.

FIG. 16displays a schematic, longitudinal view of an individual segment104′ of a flight102′ of a brake rotor preform100′ in accordance with a second example embodiment of the present invention. The segment104′ comprises one segment104′ of a plurality of segments104′ forming the flight102′, which are both, respectively, substantially similar to the segments104and flights102of the preform100of the first example embodiment of the present invention with the exception that segment104′ comprises carbon fiber precursor tow114′ oriented an angle, α, relative to the chordal direction of the segment104′. According to the second example embodiment, the angle, α, has an angular measure of approximately twenty-five degrees (25°). However, it should be appreciated and understood that in other embodiments, the angle, α, may have a different angular measure, including, but not limited to, angular measures in a range between five degrees (5°) and thirty-five degrees (35°).

FIG. 17displays a schematic, longitudinal view of an individual segment104″ of a flight102″ of a brake rotor preform100″ in accordance with a third example embodiment of the present invention. The segment104″ and flight102″ of the third example embodiment are substantially similar to the segment104and flights102of the first example embodiment, except that segment104″ comprises carbon fiber precursor tow114″ oriented at a negative angle, −α, relative to the chordal direction of the segment104″. According to the third example embodiment, the negative angle, −α, has an angular measure of approximately minus twenty-five degrees (−25°). However, it should be appreciated and understood that in other embodiments, the negative angle, −α, may have a different angular measure, including, but not limited to, angular measures in a range between minus five degrees (−5°) and minus thirty-five degrees (−35°).

While the brake rotor preforms100,100′,100″ of the example embodiments described above reduce fracturing and failure of brake rotors made therefrom, a reduction in fracturing and failure of brake rotors may also be obtained by brake pads that apply an axial force to a brake rotor30manufactured from a prior art brake preform10across the radially-extending butt joints24between segments12thereof.FIG. 18displays a schematic, longitudinal view of a brake pad170′″ configured in accordance with a fourth example embodiment of the present invention. The brake pad170′″ has an arcuate inner edge172′″ and an arcuate outer edge174′″ disposed at a distance, D, relative to the arcuate inner edge172′″ such that the brake pad170′″ forms a sector of an annulus. The brake pad170′″ has first and second ends176′″,178′″ formed between the pad's arcuate inner and outer edges172′″,174′″. The pad's first end176′″ has a wave-like shape with a series of crests180′″ and troughs182′″. The pad's second end178′″ also has a wave-like shape having a series of crests184′″ and troughs186′″. By virtue of the presence of the pad's crests180′″,184′″ and troughs182′″,186′″, the first and second ends176′″ and178′″ of the brake pad170′″ are never coplanar with a plane of a radially-extending butt joint24during use. Consequently, the axial force applied by the brake pad170′″ to a brake rotor30is distributed across the plane of a radially-extending butt joint24to multiple segments12, thereby reducing fracturing and failure of the brake rotor30.

FIG. 19displays a schematic, longitudinal view of a brake pad170″″ configured in accordance with a fifth example embodiment of the present invention that is substantially similar to the brake pad170′″ of the fourth example embodiment. However, instead of crests180′″,184′″ and troughs182′″,186′, the brake pad170″″ has a first end176″″ having a sawtooth-like shape with a series of teeth188″″ and gullets190″″. The brake pad170″″ has a second end178″″ similarly having a sawtooth-like shape with a series of teeth192″″ and gullets194″″. Similar to the brake pad170′″ of the fourth example embodiment, the first and second ends176″″ and178″″ of brake pad170″″ are never coplanar with a plane of a radially-extending butt joint24during use. As a result, the axial force applied by the brake pad170″″ to a brake rotor30is distributed across the plane of a radially-extending butt joint24to multiple segments12, thereby reducing fracturing and failure of the brake rotor30.

FIG. 20displays a schematic, longitudinal view of a brake pad170′″″ in accordance with a sixth example embodiment of the present invention. Similar to the brake pads170′″,170″″ of the fourth and fifth example embodiments, the brake pad170′″″ has an arcuate inner edge172′″″ and an arcuate outer edge174′″″ disposed at a distance, D, relative to the arcuate inner edge172′″″. Also similarly and as illustrated inFIG. 20, the brake pad170′″″ has first and second ends176′″″,178′″″ formed between the pad's arcuate inner and outer edges172′″″,174′″″. However, different from the brake pads170′″,170″″ of the fourth and fifth example embodiments, the first and second ends176′″″,178′″″ of the brake pad170′″″ of the sixth example embodiment extend linearly between the pad's arcuate inner and outer edges172′″″,174′″″. The first and second ends176′″″,178′″″ have respective lengths, L5and L6, between the pad's inner and outer edges172′″″,174′″″. The pad's first end176′″″ defines an angle, θ5, relative to a tangent196′″″ of the pad's outer edge174′″″ at the location where the pad's outer edge174′″″ and first end176′″″ intersect. The pad's second end178′″″ defines an angle, θ6, relative to a tangent198′″″ of the pad's inner edge172′″″ at the location where the pad's inner edge172′″″ and second end178′″″ intersect. According to the sixth example embodiment, the angular measures of angles θ5and θ6are equal and the lengths L5and L6of first and second ends176′″″,178′″″ are also equal.

The brake pad170′″″ of the sixth example embodiment is substantially similar in shape to the partial annular segments104of the first example embodiment. As a consequence, when used with a prior art brake rotor30, the pad's ends176′″″,178′″″ are never coplanar with the brake rotor's butt joints24during braking. Therefore, the brake pad170′ reduces fracturing and failure of the brake rotor30.

It should be appreciated and understood that brake rotor preforms100may, in other example embodiments, each include segments104having a single shape, a single orientation of carbon fiber precursor tow, multiple shapes, multiple orientations of carbon fiber precursor tow, or a combination of multiple shapes and multiple orientations of carbon fiber precursor tow. For example and not limitation, a brake rotor preform100may include segments104forming fifty percent (50%) of the preform's segments, segments104′ forming twenty-five percent (25%) of the preform's segments, and segments104″ forming twenty-five (25%) of the preform's segments. Segments104′,104″ may include respective angles, θ, having angular measures in a range of plus/minus five degrees (+/−5°) to plus/minus thirty-five degrees (+/−35°). It should be further appreciated and understood that brake pads may, in other example embodiments, have ends with shapes other than those described herein or have ends with a combination of shapes.

Whereas the present invention has been described in detail above with respect to example embodiments thereof, it should be appreciated that variations and modifications might be effected within the spirit and scope of the present invention.