Brake disc

Abstract

A brake disc (1) comprising a brake bell (2) and a braking band (3) radially outer 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), said ventilation channels (5) extending along an extent direction (Z-Z) between a radially inner air opening (6) and a radially outer air opening (7), characterized in that said ventilation channels comprise at least one rib (13) extending for at least one length along said extent direction (Z-Z).

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] The Applicant also noted that ventilation is another particularly important aspect in designing disc brakes.

[0011] It is well known indeed that in order to maximize the heat extracted from the brake disc, it is important that the air stream flows within the ventilation channels in such a way as to ensure as little pressure drops as possible, and in such a way as to maximize the heat exchange and the flow rate of the flow of overheated cooling air exiting from the radially outer edge of the braking band of the rotating disc brake.

[0012] Therefore, the Applicant was faced with the problem of making a brake disc that allows optimizing the ventilation of the brake disc, and in particular the heat exchange inside the ventilation channels.

[0013] Therefore, in a first aspect, the invention relates to a brake disc comprising a brake bell and a braking band radially outer 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.

[0014] Furthermore, the side surfaces define a plurality of ventilation channels arranged away from the axis of rotation, each ventilation channel extending along an extent direction between a radially inner opening and a radially outer opening characterized in that said ventilation channel comprises at least one rib extending for at least one length along the extent direction of the ventilation channel.

[0015] As a result, the Applicant has achieved a new optimization of heat exchange and thus cooling of the air flowing inside the ventilation channels.

[0016] For the purposes of this invention, the following definitions apply:

[0017] "Axial direction" is defined as a direction substantially coincident with or substantially parallel to the axis of rotation of the brake disc.

[0018] By "radial direction" is meant a direction substantially orthogonal to the axial direction.

[0019] By "tangential or circumferential direction" is meant a direction orthogonal to both axial and radial directions.

[0020] The present invention, in one or more preferred aspects, may comprise one or more of the following features.

[0021] Preferably, each rib extends at most for 80% of the extent of the ventilation channel in which it is located.

[0022] Advantageously, the ventilation channel comprises a maximum height, measured in a direction parallel to the axis of rotation, greater than or equal to 5 mm and the aforesaid rib has a maximum height less than or equal to 0.5 to the maximum height of the ventilation channel.

[0023] Advantageously, the rib has a maximum height greater than or equal to 2 mm.

[0024] Preferably, the rib has a maximum circumferential dimension, measured in the transverse direction, less than or equal to 10 mm.

[0025] Conveniently, the rib has a maximum circumferential dimension, measured in the circumferential direction, greater than or equal to 2 mm.

[0026] Advantageously, the aforesaid at least one rib has a variable height along its extent.

[0027] Preferably, the aforesaid at least one rib has a first length with increasing height, arranged in the vicinity of said radially outer air opening, and at least one second length with constant height, arranged consecutively to said first length.

[0028] Conveniently, the second length has an extension greater than 60% of the total rib extent.

[0029] Preferably, each ventilation channel comprises a first portion, arranged adjacent to the said radially outer air opening, directed concordantly with the extent direction of said ventilation channel, devoid of the said rib.

[0030] Conveniently, each ventilation channel comprises two facing ribs.

[0031] 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.

[0032] Brief description of the drawings

[0033] This description will be set forth hereinafter with reference to the attached drawings provided for illustration purposes only and without limitation, in which:

[0034] - figure 1 shows a schematic perspective view of a braking band of a first embodiment of the brake disc according to the invention;

[0035] - figure 2 is a side view of the braking band of figure 1;

[0036] - figure 3 is a schematic sectional view of the braking band taken along to the E-E sectional plane of figure 2;

[0037] - figure 4 is a schematic sectional view of the braking band taken along to the B-B sectional plane of figure 3; and

[0038] - figure 5 is a schematic sectional view of the braking band taken along to the A-A sectional plane of figure 3.

[0039] Detailed description of embodiments of the invention

[0040] With reference to the attached figures, a brake disc according to the present invention is generally denoted by 1.

[0041] The brake disc 1 comprises and is constituted by a metal brake bell 2 and a braking band 3 radially outside the latter.

[0042] The metal brake bell 2 and the braking band 3 extend around a common central axis of rotation denoted by X-X.

[0043] 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.

[0044] 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.

[0045] A plurality of ventilation channels 5 is defined and formed between the two side surfaces 4 belonging to the braking band 3.

[0046] 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 outer edge of the braking band 3.

[0047] The ventilation channels 5 are preferably arranged inclined with respect to a direction radial to the axis of rotation X-X.

[0048] 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.

[0049] Furthermore, the extent axis Z-Z of the ventilation channels forms an angle a, with a radial direction, greater than or equal to 10°. 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.

[0050] 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.

[0051] Each ventilation channel 5 comprises at least one radially inner air opening 6 facing the axis of rotation X-X, one radially outer air opening 7 arranged at the radially outer edge of the braking band 3.

[0052] Each radially inner air opening 6 has an area greater than or equal to 36 mm2.

[0053] Each radially outer air opening 7 has an area greater than or equal to the area of the radially inner air opening 6.

[0054] Each radially outer air opening 7 has an area less than or equal to 700 mm2.

[0055] Each ventilation channel 5 has a maximum height H, measured in a direction parallel to the axis of rotation X-X, greater than or equal to 5 mm.

[0056] Preferably, the maximum height H of the ventilation channel is less than or equal to 30 mm.

[0057] Furthermore, each ventilation channel 5 comprises one or more side walls 5' arranged, according to the Z-Z extent direction, between the radially inner air opening 6 and the radially outer air opening 7.

[0058] The side walls 5’, arranged around the Z-Z extent axis, laterally define the ventilation channel itself.

[0059] In the embodiment shown in the figures, there are four side walls 5’ two by two facing each other. According to this embodiment, at least one length of the ventilation channel 5 has, indeed, a substantially quadrangular cross-section.

[0060] Furthermore, each ventilation channel 5 comprises at least one rib 13 extending, from a side wall 5', for at least one length along the extent direction Z-Z of the ventilation channel itself.

[0061] Preferably, the rib 13 extends at most for 80% of the extent of the ventilation channel 5 in which it is located. Each rib 13 extends not only along the extent direction of the ventilation channel 5 but also toward the inside of the ventilation channel 5.

[0062] For this purpose, the rib 13 has a maximum height h less than or equal to 0.5 times the maximum height H of the ventilation channel 5.

[0063] Preferably, the rib 13 has a maximum height h greater than or equal to 2 mm.

[0064] In the embodiment shown in the figures, the rib 13 has a variable height along its extent.

[0065] In particular, with reference to figure 4, the rib 13 has a first length 13' arranged in the vicinity of the radially outer air opening 7 at increasing height while approaching the axis of rotation X-X, i.e., a length in which the rib 13 is further away from the side wall 5' from which it extends, and at least a second length 13' arranged consecutively to the first length 13'.

[0066] The second length 13" has essentially constant height along its extent in the direction of the extent axis Z-Z.

[0067] In other words, in the second length 13", the height of rib 13 is essentially constant relative to the side wall 5’ from which it extends.

[0068] The second length 13" has an extent greater than 60% of the total extent of the rib 13.

[0069] The second length 13" has an extent less than 80% of the total extent of the rib 13.

[0070] Furthermore, in the embodiment shown in the figures, the rib 13 has a third length 13" arranged consecutively to the second length 13" and in the vicinity of the radially inner air opening 6.

[0071] The third length 13" has limited extent, preferably less than 5% of the extent of the ventilation channel 5.

[0072] The third length 13" has a decreasing height, while approaching the axis of rotation X-X.

[0073] Inside the ventilation channel 5, the rib 13 also extends in the circumferential direction. In particular, the rib has a maximum circumferential dimension, measured precisely in the circumferential direction, greater than or equal to 2 mm.

[0074] The second length 13" has an extent greater than 60% of the total extent of the rib 13.

[0075] Preferably, the rib 13 has a maximum circumferential dimension, measured in the circumferential direction, less than or equal to 10 mm.

[0076] In the embodiment shown in the figures, the circumferential dimension of the rib 13 varies along the extent direction of the rib itself.

[0077] Still referring to the embodiment shown in the figures, the ventilation channel 5 comprises a first portion or length 14 arranged adjacent to the radially outer air opening 7, devoid of the rib 13.

[0078] Therefore, the rib 13 extends beyond such length 14.

[0079] In the embodiment shown in the figures, each ventilation channel 5 has two facing ribs 13.

[0080] The two ribs 13 are, preferably, equal in shape and size but specular with respect to the extent direction Z-Z.

[0081] According to other embodiments, the ventilation channel 5 could have multiple ribs 13, for example four, without departing from the scope of protection of the present invention.

[0082] Still referring to the embodiment shown in the figures, it can be noted that all ventilation channels 5 have two facing ribs 13, however, different configurations of the brake disc 1 could be used where only some ventilation channels 5 have the rib 13 and / or in which the ribs 13, inside the same ventilation channel 5 or different ventilation channels 5, are different in shape and / or size.

[0083] 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.

[0084] 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. 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.

[0085] The inner ring 10 may have at least one coupling element 23 that runs substantially orthogonally to the median plane M-M from a side face 8 of the inner ring 10.

[0086] With reference to figures 2 and 3 and according to the preferred embodiment, the inner ring 10 has not just one but a plurality of coupling elements 23 distributed along a coupling circumference 20 concentric to the central axis of rotation X-X.

[0087] The coupling elements 23 provide a seat for housing coupling means 24, typically screw coupling means, and are configured to allow coupling between the metal brake bell 2 and the braking band 3.

[0088] The coupling elements 23 are spaced angularly, preferably consistently along the coupling circumference 20.

[0089] Preferably, there are eight to fourteen coupling elements 23 per brake disc 1, even more preferably there are nine to thirteen coupling elements 23 per brake disc 1.

[0090] Thanks to the above described features provided separately or in combination, it is possible to provide a solution to the cooling needs of the brake disc with optimized heat transfer inside the ventilation channels.

[0091] 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. Brake disc (1) comprising a brake bell (2) and a braking band (3) radially outer 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), said ventilation channels (5) extending along an extent direction (Z-Z) between a radially inner air opening (6) and a radially outer air opening (7), characterized in that said ventilation channels comprise at least one rib (13) extending for at least one length along said extent direction (Z-Z).

2. Brake disc (1) according to claim 1, characterized in that said rib (13) extends at most for 80% of the extent of the ventilation channel (5) in which it is located.

3. Brake disc (1) according to claim 1, characterized in that said ventilation channel (5) comprises a maximum height (H), measured in a direction parallel to said axis of rotation (X-X), greater than or equal to 5 mm and said rib (13) has a maximum height (h) less than or equal to 0.5 to said maximum height (H) of the ventilation channel (5).

4. Brake disc (1) according to claim 3, characterized in that said maximum height (h) of said rib is greater than or equal to 2 mm.

5. Brake disc (1) according to claim 1, characterized in that said rib (13) has a maximum circumferential dimension, measured in circumferential direction, less than or equal to 10 mm.

6. Brake disc (1) according to claim 1, characterized in that said rib has a maximum circumferential dimension, measured in circumferential direction, greater than or equal to 2 mm.

7. Brake disc (1) according to any one of preceding claims 1 to 6, characterized in that said rib (13) has a variable height along its extent.

8. Brake disc (1) according to claim 7, characterized in that said rib (13) has a first length (13’) with increasing height, arranged in the vicinity of said radially outer air opening (7), and at least one second length (13”) with constant height, arranged consecutively to said first length (13’).

9. Brake disc (1) according to claim 8, characterized in that said second length (13”) has an extent greater than 60% of the total extent of said rib (13).

10. Brake disc (1) according to any one of preceding claims 1 to 9, wherein each ventilation channel (5) comprises a first portion, arranged adjacent to said radially outer air opening (7), said first portion being devoid of said rib (13).

11. Brake disc (1) according to any one of the preceding claims, characterized in that each ventilation channel (5) comprises two facing ribs (13).

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