Brake disc

Abstract

A brake disc (1) comprising a brake bell (2) and a braking band (3) radially external with respect to the latter is described, said band (2) and said brake bell (3) extending around a common axis of rotation (X-X); said braking band (2) being made of a composite material and having side braking surfaces (4) adapted to cooperate with a respective brake caliper thus exerting a braking action on the vehicle on which said brake disc (1) is installed; said side surfaces (4) defining, in addition, a plurality of ventilation channels (5) arranged away from the axis of rotation (X-X), each provided with a radially inner air opening (6); said braking band (2) being provided with an inner ring (10) provided with a median plane (M-M) and two side faces (8-9), said inner ring being provided with a plurality of dragging holes (1) configured to couple said brake bell to said braking band; said inner ring (10) being, in addition, provided with a radially inner free end, characterized in that said inner ring (10) has a plurality of notches (30) extending radially from the radially inner free end to the outside of said braking band (3), said notches (30) being arranged at said dragging hole (21).

Description

[0001] BRAKE DISC

[0002] Field of the invention

[0003] The present invention relates to a brake disc for disc braking systems. In particular, the invention relates to brake discs for high-performance vehicles, provided with a braking annulus or band made of carbonaceous-matrix composite material, coaxially and internally to which a metal bell-shaped element integral with it is provided.

[0004] Known art

[0005] The following documents describe some examples of braking systems in particular provided with braking band made of carbonaceous-matrix composite material: WO2019043616 and WO2016 / 199021.

[0006] Summary of the invention

[0007] As is well known, the so-called carbonaceous-matrix discs are also normally known as carbon discs or carbon-ceramic discs.

[0008] Brake discs may comprise a braking band and a brake bell that are made in separate pieces and assembled by using at least one connecting device.

[0009] The connection between the braking band and the brake bell is very important because it ensures the braking torque from the braking band to the brake bell to be transferred. Tangential constraint between the braking band and the brake bell can be made with systems that provide protuberances of the braking band that couple in respective brake bell seats so as to make a tangential constraint system between braking band and brake bell that has a particularly simple structure and thus low production costs.

[0010] However, the Applicant noted that such coupling systems are often made in such a way as to increase thermal and mechanical stresses due to tangential forces operating in this area at the expense of product longevity.

[0011] Therefore, the Applicant was faced with the problem of making a brake disc that would improve the coupling area between the brake bell and the braking band, in particular reducing thermal and mechanical stresses and, at the same time, providing good elasticity qualities in this area.

[0012] Therefore, in a first aspect, the invention relates to a brake disc comprising a brake bell and a braking band radially external with respect to the latter, said band and said brake bell extending around a common axis of rotation; said braking band being made of a composite material and having side braking surfaces adapted to cooperate with a respective brake caliper thus exerting a braking action on the vehicle on which said brake disc is installed; said side surfaces defining, in addition, a plurality of ventilation channels arranged away from the axis of rotation, each provided with a radially inner air opening; said braking band being provided with an inner ring provided with a median plane and two side faces, said inner ring comprising a plurality of dragging holes configured to couple, by fixing means, typically screw elements, said brake bell to said braking band; said inner ring being, in addition, provided with a radially inner free end, characterized in that said inner ring has a plurality of notches extending radially from the radially inner free end to the outside of said braking band, said notches being arranged at the dragging holes.

[0013] Thus, the Applicant has achieved a new optimization of the connection between brake bell and braking band, which allows thermo-mechanical stresses to which this area is usually subjected to be reduced.

[0014] For the purposes of this invention, the following definitions apply:

[0015] "Axial direction" is defined as a direction substantially coincident with or substantially parallel to the axis of rotation of the brake disc.

[0016] By "radial direction" is meant a direction substantially orthogonal to the axial direction.

[0017] By "tangential or circumferential direction" is meant a direction orthogonal to both axial and radial directions.

[0018] By "arranged on the extension" referring to the positioning of a first element with respect to a second element, is meant the condition in which the prevailing extent direction of a first element, such as the side wall of a ventilation channel, is arranged with respect to the extent direction of a second element, such as the first side wall of a tower-shaped element, so that the two directions coincide or differ by an angle, between them, of at most equal to 10°.

[0019] The present invention, in one or more preferred aspects, may comprise one or more of the following features.

[0020] Conveniently, each notch can be inscribed in a circumference having radius equal to or less than 12 mm, preferably equal to or less than 11 mm.

[0021] Advantageously, each notch can be inscribed in a circumference having radius equal to or greater than 2 mm, preferably equal to or greater than 3 mm.

[0022] Preferably, each notch has a substantially circular segment shape, with the concavity facing said axis of rotation.

[0023] Conveniently, each notch has a maximum radial direction less than or equal to 20 mm.

[0024] Advantageously, each notch has a maximum radial direction greater than or equal to 4 mm.

[0025] Preferably, the notches of said plurality of notches are equal in number to the dragging holes.

[0026] Conveniently, there are eight to fourteen notches per brake disc.

[0027] Preferably, each notch is arranged at a tower-shaped element so as to be completely positioned at a maximum angular distance in the circumferential direction of less than 45°.

[0028] Conveniently, considering a counterclockwise direction, each notch is arranged directly upstream of a dragging hole.

[0029] Further characteristics and advantages of the invention will become clearer from the detailed description of some preferred, but not exclusive, embodiments of a brake disc according to the present invention.

[0030] Brief description of the drawings

[0031] This description will be set forth hereinafter with reference to the attached drawings provided for illustration purposes only and without limitation, in which:

[0032] - figure 1 shows a schematic perspective view of a braking band of a first embodiment of the brake disc according to the invention; - figure 2 is a side view of the braking band of figure 1;

[0033] - figure 3 is a schematic sectional view of the braking band taken along to the E-E sectional plane of figure 2;

[0034] - figure 4 is a schematic enlarged view of a tower-shaped element according to the present invention.

[0035] Detailed description of embodiments of the invention

[0036] With reference to the attached figures, a brake disc according to the present invention is generally denoted by 1.

[0037] The brake disc 1 comprises and is constituted by a metal brake bell 2 and a braking band 3 radially outside the latter.

[0038] The metal brake bell 2 and the braking band 3 extend around a common central axis of rotation denoted by X-X.

[0039] The axis of rotation defines an axial direction X-X coincident with or parallel to the axis of rotation, a radial direction R-R orthogonal to the axial direction X-X, and a tangential direction T-T or circumferential direction T-T orthogonal to both the axial direction X-X and the radial direction R-R.

[0040] The braking band 3, made of a composite material such as a carbon-ceramic type, is provided with two side braking surfaces denoted by 4, which are adapted to be engaged by a brake caliper (not shown) of a disc braking system.

[0041] A plurality of ventilation channels 5 is defined and formed between the two side surfaces 4 belonging to the braking band 3.

[0042] The ventilation channels 5 extend away from the axis of rotation X-X along an extent axis Z-Z, preferably substantially rectilinear, substantially to the radially external edge of the braking band 3.

[0043] The ventilation channels 5 are preferably arranged inclined with respect to a direction radial to the axis of rotation X-X.

[0044] In other words, the extent axis Z-Z of the ventilation channels 5 forms an angle a greater than or equal to 30°, preferably greater than or equal to 40°, even more preferably less than or equal to 70°, with a radial direction to the axis of rotation X-X. Furthermore, the extent axis Z-Z of the ventilation channels forms an angle a, with a radial direction, greater than or equal to 10°.

[0045] Preferably, the ventilation channels 5 do not have a constant cross-section, along their extent axis Z-Z, but a cross section that increases away from the axis of rotation X-X.

[0046] By cross section of a ventilation channel 5 is meant a cross section of the ventilation channel 5 substantially orthogonal to the extent axis Z-Z of the ventilation channel 5 itself.

[0047] Each ventilation channel 5 comprises at least one radially inner opening 6 facing the axis of rotation X-X, one radially external opening 7 arranged at the radially external edge of the braking band 3, two side walls 5'.

[0048] The side walls 5’ are directed in plan substantially in accordance with the extent direction Z-Z.

[0049] Each radially inner opening 6 has an area greater than or equal to 36 mm2.

[0050] Each radially external opening 7 has an area greater than or equal to the area of the radially inner opening 6.

[0051] Furthermore, the brake disc 1 comprises a brake bell 2, which is adapted to be operationally connected to a vehicle wheel that can be combined with the braking band 3.

[0052] The braking band 3 is provided with a radially inner ring 10, which is preferably flat and continuous, wherein M-M indicates its median plane.

[0053] The continuous inner ring 10 has two side faces 8, 9 of which, with reference to figure 1, one faces upward 8 and one faces downward 9.

[0054] The inner ring 10 may have at least one dragging hole 21 on which a towershaped element 13 that runs substantially orthogonally to the median plane M-M from a side face 8 of the inner ring 10 is positioned.

[0055] With reference to figures 2 and 3 and according to the preferred embodiment, the inner ring 10 has a plurality of dragging holes 21 and tower-shaped elements 13 distributed along a coupling circumference 20 concentric to the central axis of rotation X-X. The tower-shaped elements 13 provide a seat 27, which is coaxial and, preferably, with the same radius of the dragging holes 21, for housing coupling means 24, typically screw coupling means, and are both configured to allow coupling between the metal brake bell 2 and the braking band 3. The dragging holes 21 and the tower-shaped elements 13 are spaced angularly, preferably consistently along the coupling circumference 20.

[0056] Preferably, the dragging holes 21 and the tower-shaped elements 13 are mutually placed at a distance, measured at two corresponding points on two dragging holes 21 or two adjacent tower-shaped elements 13, greater than or equal to 20 mm, preferably greater than or equal to 40 mm.

[0057] The dragging holes 21 and the tower-shaped elements 13 are mutually placed at a distance, measured at two corresponding points on two dragging holes 21 or two adjacent tower-shaped elements 13, less than or equal to 80 mm. Preferably, there are eight to fourteen dragging holes 21 per brake disc 1, even more preferably there are nine to thirteen dragging holes 21 per brake disc 1.

[0058] Furthermore, there are eight to fourteen tower-shaped elements 13 per brake disc 1, preferably there are nine to thirteen tower-shaped elements 13 per brake disc 1.

[0059] Preferably, each tower-shaped element 13 extends orthogonally from the median plane M-M for a height at most equal to the height of the braking band 3 with respect to the median plane M-M.

[0060] Each tower-shaped element 13 is arranged at the radially inner opening 6 of a ventilation channel 5, so as to have a first rectilinear side wall 14 substantially arranged on the extension of a side wall of the ventilation channel 5.

[0061] Preferably, the tower-shaped elements 13 are not made in one piece with the brake plate 3 but are removable from the latter and are preferably disjointed from the ventilation channels 5.

[0062] Furthermore, the tower-shaped elements 13 are made removable from the inner ring 10. Furthermore, each tower-shaped element 13 has a first curvilinear side wall 15 arranged consecutively to the first rectilinear side wall 14 and in such a way that it does not completely obstruct the radially inner opening 6.

[0063] In particular, the first curvilinear side wall 15 is arranged so that it does not completely obstruct the radially inner opening of the ventilation channel 5 adjacent to the one at the extension of which the first rectilinear side wall 14 is arranged.

[0064] The first curvilinear wall has a radius of curvature Rl.

[0065] Preferably, the tower-shaped elements 13 also have a second curvilinear side wall 16 and a second rectilinear side wall 17.

[0066] Preferably, as in the embodiment shown in the figures, the tower-shaped elements 13 have a second curvilinear side wall 16 provided with a smaller radius of curvature than the first curvilinear side wall 15.

[0067] The first curvilinear side wall 15 has a radius of curvature Rl greater than or equal to 1 / 2 the radius of curvature R2 of the second curvilinear side wall 16.

[0068] The first 14 and second 17 rectilinear side walls extend between the two curvilinear side walls 15, 16 so as to join them and form in plan a substantially teardrop shape of the tower-shaped element 13.

[0069] The first side wall 14 is arranged in plan along an extent direction forming an angle P of less than or equal to 45°, preferably less than or equal to 30°, greater than or equal to 10° with the extent direction of the second side wall 17.

[0070] Furthermore, the first side wall 14 of a tower-shaped element 13 is arranged in plan with the first side wall 14 of the circumferentially consecutive tower-shaped element 13 so as to form an angle y of less than or equal to 45°.

[0071] This way, the first 14 and second 17 rectilinear side walls of a tower-shaped element 13 act synergistically with the first rectilinear side wall 14 of the circumferentially consecutive tower-shaped element 13, to direct the air flow to the radially inner openings 6 of the ventilation channels 5 that are between the two consecutive tower-shaped elements 13.

[0072] Each first curvilinear portion 15 is arranged so as to be positioned in plan at least partially overlapping, but not in contact with, the radially inner opening 6 of the ventilation channel 5 adjacent to that on the extension of a side wall of which the first rectilinear wall of the tower-shaped element 13 itself is.

[0073] The tower-shaped element 13 is arranged so that the first curvilinear portion 15 overlaps at most with 50% of the maximum width, in plan, of the radially inner opening 6 of the ventilation channel 5.

[0074] The tower-shaped element 13 is arranged so that the first curvilinear portion 15 overlaps at least 5% of the maximum width, in plan, of the radially inner opening 6 of the ventilation channel 5.

[0075] The center of the first radius of curvature R1 and the second radius of curvature R2 identify a main extent axis, passing through them, of the tower-shaped element 13.

[0076] The dimension measured along the extent axis between the two centers of the first R1 and second R2 radii of curvature are representative of the extent dimension D of each tower-shaped element 13.

[0077] The extent dimension D of each tower-shaped element 13 is preferably less than or equal to 30 mm.

[0078] The extent dimension D of each tower-shaped element 13 is preferably greater than or equal to 5 mm.

[0079] Advantageously, all tower-shaped elements 13 of the same brake disc are equal in shape and size.

[0080] For the purpose of improving the structural strength of the coupling area between the brake bell 2 and the braking band 3, the inner ring 10 is advantageously provided with a plurality of notches 30 that run radially from the radially inner free end of the inner ring 10 toward the outside of the braking band 3.

[0081] The notches 30 are through-notches, in other words they make a gap for the entire thickness of the inner ring 10.

[0082] The notches 30 are arranged at the dragging holes 21 and, with reference to the embodiment depicted in the figures, also at the tower-shaped elements 13.

[0083] Preferably, considering a counterclockwise direction depicted by the arrow F in figure 1, each notch 30 is arranged directly upstream of a dragging hole 21 and a tower-shaped element 13. In each brake disc 1, there are as many notches 30 as dragging holes 21, in other words the notches 30, the dragging holes 21 and the tower-shaped elements 13 are in the ratio of one to one in each inner ring 10.

[0084] Preferably, there are eight to fourteen notches 30 per brake disc 1.

[0085] In the preferred embodiment shown in the figures, there are twelve notches 30.

[0086] Preferably, each notch 30 is arranged on the inner ring 10 at a dragging hole 21 and consequently at a tower-shaped element 13, so as to be completely positioned at a maximum angular distance in the circumferential direction of less than 45°.

[0087] In the embodiment shown in the figures, the notches 30 and the adjacent towershaped elements 13 have no common points, in other words each tower-shaped element 13 does not span the gap generated by the adjacent notch 30 in the inner ring 10.

[0088] The notches 30 are configured to lighten the inner ring 10, thus giving it greater elasticity.

[0089] Thus, on the one hand, the notches 30 should not extend excessively so as not to structurally weaken the inner ring 10 but, on the other hand, they should have a minimum extent such that the inner ring 10 can achieve the desired performance in terms of elasticity.

[0090] Thus, for this purpose, each notch 30 can be inscribed in a circumference having radius equal to or less than 12 mm, preferably equal to or less than 11 mm.

[0091] Preferably, still for this purpose, each notch 30 can be inscribed in a circumference having radius equal to or greater than 2 mm, preferably equal to or greater than 3 mm.

[0092] In the preferred embodiment shown in the figures, each notch 30 has a substantially circular segment shape, with the concavity facing the axis of rotation X- X.

[0093] In detail, the notches 30 extend radially from the radially inner free end of the inner ring 10 toward the outside of braking band 3 with their concavity facing the axis of rotation X-X. Each notch 30 has a maximum radial direction d less than or equal to 20 mm, preferably less than or equal to 18 mm.

[0094] Preferably, each notch 30 has a maximum radial direction d greater than or equal to 4 mm. Except for the section at the inner edge of the inner ring 10, the notches 30 are substantially in the shape of a semicircle in plan.

[0095] All of the notches 30 of the inner ring 10 have substantially the same shape and the same arrangement on the inner ring 10 with respect to the adjacent tower-shaped element 13 and the axis of rotation X-X, except for their circumferential offset. Thanks to the above described features provided separately or in combination, it is possible to provide a solution to the needs of the coupling area between brake bell and braking band and to achieve the aforesaid advantages, in particular:

[0096] - mechanical and thermo-mechanical stresses on the braking surfaces of the braking band are reduced; - disk life in terms of vehicle mileage is increased, particularly for applications on high-performance vehicles, such as race cars.

[0097] Various modifications may be made to the embodiments described in detail, all anyhow remaining within the protection scope of the invention, as defined by the following claims.

Claims

CLAIMS1. A brake disc (1) comprising a brake bell (2) and a braking band (3) radially external with respect to the latter, said band (2) and said brake bell (3) extending around a common axis of rotation (X-X); said braking band (2) being made of a composite material and having side braking surfaces (4) adapted to cooperate with a respective brake caliper thus exerting a braking action on the vehicle on which said brake disc (1) is installed; said side surfaces (4) defining, in addition, a plurality of ventilation channels (5) arranged away from the axis of rotation (X-X), each provided with a radially inner air opening (6); said braking band (2) being provided with an inner ring (10) provided with a median plane (M-M) and two side faces (8-9), said inner ring (10) comprising a plurality of dragging holes (1) configured to couple said brake bell to said braking band; said inner ring (10) being, in addition, provided with a radially inner free end, characterized in that said inner ring (10) has a plurality of notches (30) extending radially from the radially inner free end to the outside of said braking band (3), said notches (30) being arranged at said dragging hole (21).

2. Brake disc (1) according to claim 1, characterized in that each notch (30) can be inscribed in a circumference having radius equal to or less than 12 mm.

3. Brake disc (1) according to claim 1, characterized in that each notch (30) can be inscribed in a circumference having radius equal to or greater than 2 mm.

4. Brake disc (1) according to any one of preceding claims 1 to 3, characterized in that each notch has a substantially circular segment shape, with the concavity facing said axis of rotation (X-X).

5. Brake disc (1) according to any one of preceding claims 1 to 4, characterized in that each notch (30) has a maximum radial direction (d) less than or equal to 20 mm.

6. Brake disc (1) according to any one of preceding claims 1 a 4, characterized in that each notch (30) has a maximum radial direction (d) greater than or equal to 4 mm.

7. Brake disc (1) according to any one of preceding claims 1 a 6, characterized in that the notches (30) of said plurality of notches are equal in number to the tower-shaped elements (13).

8. Brake disc (1) according to any one of preceding claims 1 a 7, characterized in that there are eight to fourteen notches (30) per brake disc (1).

9. Brake disc (1) according to any one of preceding claims 3 a 5, characterized in that each notch (30) is arranged at a dragging hole (21) so as to be completely positioned at a maximum angular distance of less than 45° in the circumferential direction.

10. Brake disc (1) according to any one of preceding claims 1 a 4, characterized in that, considering a counterclockwise direction, each notch is arranged directly upstream of a dragging hole (21).

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