Brake disc

Abstract

A brake disc (1) is described, comprising a brake bell (2) and a braking band (3) radially outer with respect to the latter, said band (3) and said brake bell (2) extending around a common axis of rotation (X-X); said braking band (3) having side braking surfaces (4) adapted to cooperate with a respective brake caliper and exerting a braking action on the vehicle on which said brake disc (1) is installed; said side surfaces (4) further defining 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 (5) comprise, away from said axis of rotation (X-X), at least one rectilinear length (11) and at least one curvilinear length (12) arranged consecutively to said rectilinear length (11); -said rectilinear length (11) having an extent greater than said curvilinear length (12); said curvilinear length (12) flowing into said radially outer air opening (7).

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 therewith 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, the band and the brake bell extending around a common axis of rotation; the 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, said ventilation channels extending along an extent direction between a radially inner air opening and a radially outer air opening, characterized in that said ventilation channels comprise, away from said axis of rotation, at least one rectilinear length and at least one curvilinear length arranged consecutively to the rectilinear length;

[0014] -said rectilinear length having an extent greater than said curvilinear length; said curvilinear length flowing into said radially outer air opening.

[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 the present 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] “Tangential or circumferential direction” means a direction orthogonal to both the 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, the aforesaid at least one rectilinear length has an extent greater than or equal to 55% of the total extent of the ventilation channel and less than or equal to 90% of the total extent of the ventilation channel.

[0022] Advantageously, the aforesaid at least one rectilinear length has an extent greater than or equal to 70% of the total extent of the ventilation channel.

[0023] Advantageously, the aforesaid at least one rectilinear length can extend away from the axis of rotation in an extent direction so as to form a first angle of inclination a’, with a direction radial to the axis of rotation, less than or equal to 60°.

[0024] Preferably, the first angle of inclination can be constant along the extent of the first length of the ventilation channel.

[0025] Conveniently, the aforesaid at least one curvilinear length extends away from the axis of rotation X-X in an extent direction so as to form a second angle of inclination a”, with a direction radial to the axis of rotation, less than the first angle of inclination a’.

[0026] Advantageously, the second angle of inclination a” is less than or equal to 50° and greater than or equal to 10°.

[0027] Preferably, the second angle of inclination a” varies decreasingly away from the axis of rotation along the extent of said second length.

[0028] Alternatively, said at least one curvilinear length extends away from the axis of rotation in an extent direction so as to form a second angle of inclination a”, with a direction radial to the axis of rotation, greater than the first angle of inclination a’.

[0029] Preferably, in this case, the second angle of inclination a” is less than or equal to 90° and greater than or equal to 70°.

[0030] Conveniently, the ventilation channels comprise an increasing width radially away from said axis of rotation.

[0031] Advantageously, the width of the curvilinear length can be greater than or equal to Lr, wherein Lr is the maximum width of the rectilinear length.

[0032] Preferably, the width of the curvilinear length can be less than or equal to 5 Lr.

[0033] 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.

[0034] Brief description of the drawings This description will be set forth hereinafter with reference to the attached drawings provided for illustration purposes only and without limitation, in which:

[0035] - figure 1 shows a schematic perspective view of a braking band of a first embodiment of the brake disc according to the invention;

[0036] - figure 2 is a sectional side view of the braking band of figure 1;

[0037] - figure 3 is a schematic sectional view of the braking band taken along to the M-M sectional plane of figure 2;

[0038] - figure 4 is an enlarged schematic view of a portion of the braking band 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 towards the radially outer edge of the braking band 3. 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.

[0047] Each radially inner air opening 6 has an area greater than or equal to 36 mm2. Each radially outer air opening 7 has an area greater than or equal to the area of the radially inner air opening 6.

[0048] Each radially outer air opening 7 has an area less than or equal to 700 mm2.

[0049] 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.

[0050] Preferably, the maximum height H of the ventilation channel is less than or equal to 30 mm.

[0051] Furthermore, each ventilation channel 5 comprises one or more side walls 5' arranged, in the extent direction, between the radially inner air opening 6 and the radially outer air opening 7.

[0052] The side walls 5’, arranged around the extent direction, laterally define the ventilation channel itself.

[0053] In the embodiment shown in the figures, there are four side walls 5’ two by two facing each other.

[0054] According to this embodiment, the ventilation channel 5 has, indeed, a substantially quadrangular cross-section.

[0055] Preferably, the ventilation channels 5 do not have a constant cross-section, along their extent direction, but a cross section that increases, at least at the first length 11, away from the axis of rotation X-X.

[0056] By cross section of a ventilation channel 5 is meant a section of the ventilation channel 5 substantially orthogonal to the extent direction of the ventilation channel 5 itself.

[0057] The ventilation channels 5, away from the axis of rotation X-X, are formed by a rectilinear length 11 and a curvilinear length 12 arranged consecutively to the rectilinear length 11.

[0058] The rectilinear length 11 extends from the radially inner opening 6 and has an extent greater than the curvilinear length 12, the latter, as can be seen in the attached figures, flows into the radially outer air opening 7. Preferably, each ventilation channel 5 is only formed by the rectilinear length 11 and the curvilinear length 12 and there are no further typologies, in terms of shape or size, of lengths of ventilation channel.

[0059] As previously mentioned, the rectilinear length 11 of the ventilation channel 5 has a preponderant extent compared to the curvilinear length 12 and in general compared to the total extent of the ventilation channel 5 itself.

[0060] Preferably, the rectilinear length 11 has an extent greater than or equal to 55% of the total extent of the ventilation channel 5 and less than or equal to 90% of the total extent of the ventilation channel 5.

[0061] More preferably, the rectilinear length 11 has an extent greater than or equal to 60% of the total extent of the ventilation channel 5.

[0062] Even more preferably, the rectilinear length 11 has an extent greater than or equal to 70% of the total extent of the ventilation channel 5.

[0063] In the rectilinear length 11, each ventilation channel 5 has an increasing width radially away from the axis of rotation X-X.

[0064] The maximum width Lr of the rectilinear length 11 is preferably between 5 mm and 50 mm.

[0065] Preferably, the rectilinear length 11 extends away from the axis of rotation X-X in an extent direction adapted to form a first angle of inclination a’ with a direction radial to the axis of rotation X-X, less than or equal to 60°.

[0066] Preferably, the first angle of inclination a’ is greater than or equal to 15°. Even more preferably, the first angle of inclination a’ is greater than or equal to 30° and less than or equal to 50°.

[0067] Preferably, the first angle of inclination a’ is substantially constant throughout the extent of the rectilinear length 11.

[0068] As previously mentioned, the rectilinear length 11 of the ventilation channel 5 is followed by a curvilinear length 12 radially away from the axis of rotation X-X.

[0069] The curvilinear length has an extent less than the first rectilinear length 11. Preferably, the curvilinear length 12 has an extent greater than or equal to 5% of the total extent of the ventilation channel 5 and less than or equal to 30% of the total extent of the ventilation channel 5.

[0070] Even more preferably, the curvilinear length 12 has an extent less than or equal to 15% of the total extent of the ventilation channel 5.

[0071] In the embodiment shown in the figures, the curvilinear length 12 of each ventilation channel 5 has a substantially constant or slightly increasing width, radially away from the axis of rotation X-X.

[0072] The maximum width Lr of the curvilinear length 12 is preferably between 5 mm and 100 mm.

[0073] With reference to the preferred embodiment shown in the figures, the curvilinear length 12 extends away from the axis of rotation X-X in an extent direction adapted to form a second angle of inclination a”, with a direction radial to the axis of rotation X- X, less than the first angle of inclination a’ of the rectilinear length 11.

[0074] Preferably, the second angle of inclination a” is less than or equal to 50° and greater than or equal to 10°.

[0075] The second angle of inclination a” varies decreasingly away from the axis of rotation X-X along the extent of the curvilinear length 12.

[0076] According to an alternative embodiment not shown in the figures, the curvilinear length 12 could extend away from the axis of rotation in an extent direction so as to form a second angle of inclination a”, with a direction radial to the axis of rotation, greater than the first angle of inclination a’ .

[0077] Preferably, in this case, the second angle of inclination a” is less than or equal to 90° and greater than or equal to 70°.

[0078] In other words, according to this embodiment, the curvilinear length extends circumferentially in a direction opposite to that shown in the figures.

[0079] 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. 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] The coupling elements 23 are spaced angularly, preferably consistently along the circumference named coupling circumference 20.

[0085] 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.

[0086] 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.

[0087] Various modifications may be made to the embodiments described in detail, all anyhow remaining within the scope of protection 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 braking band (3) and said brake bell (2) extending around a common axis of rotation (X-X); said braking band (3) having side braking surfaces (4) adapted to cooperate with a respective brake caliper and exerting a braking action on the vehicle on which said brake disc (1) is installed; said side surfaces (4) further defining 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 (5) comprise, away from said axis of rotation (X-X), at least one rectilinear length (11) and at least one curvilinear length (12) arranged consecutively to said rectilinear length (11);-said rectilinear length (11) having an extent greater than said curvilinear length (12); said curvilinear length (12) flowing into said radially outer air opening (7).

2. Brake disc (1) according to claim 1, characterized in that said at least one rectilinear length (11) has an extent greater than or equal to 55% of the total extent of the ventilation channel (5) and less than or equal to 90% of the total extent of said ventilation channel (5).

3. Brake disc (1) according to claim 2, characterized in that said at least one rectilinear length (11) has an extent greater than or equal to 70% of the total extent of the ventilation channel (5).

4. Brake disc (1) according to claim 3, characterized in that said at least one rectilinear length (11) extends away from the axis of rotation (X-X) in an extent direction (Z-Z) so as to form a first angle of inclination a’, with a direction radial to the axis of rotation (X-X), less than or equal to 60°.

5. Brake disc (1) according to claim 4, characterized in that said first angle of inclination a’ is substantially constant along the extent of said rectilinear length (11).

6. Brake disc (1) according to claim 3, characterized in that said at least one curvilinear length (12) extends away from the axis of rotation (X-X) in an extentdirection (Z-Z) so as to form a second angle of inclination a”, with a direction radial to the axis of rotation (X-X), less than said first angle of inclination a’.

7. Brake disc (1) according to claim 3, characterized in that said at least one curvilinear length (12) extends away from the axis of rotation (X-X) in an extent direction (Z-Z) so as to form a second angle of inclination a”, with a direction radial to the axis of rotation (X-X), greater than said first angle of inclination a’.

8. Brake disc (1) according to claim 6, characterized in that said second angle of inclination a’ ’ is less than or equal to 50° and greater than or equal to 10°.

9. Brake disc (1) according to claim 7, characterized in that said second angle of inclination a’ ’ is less than or equal to 90° and greater than or equal to 70°.

10. Brake disc (1) according to claims 6 or 7, characterized in that said second angle of inclination a” varies decreasingly away from said axis of rotation (X- X) along the extent of said second length (12).

11. Brake disc (1) according to any one of preceding claims 1 to 8, characterized in that said ventilation channels (5) comprise an increasing width radially away from said axis of rotation (X-X).

12. Brake disc (1) according to claim 9, characterized in that the width of said curvilinear length (12) is greater than or equal to Lr, wherein Lr is the width of said rectilinear length (11).

13. Brake disc (1) according to claim 10, characterized in that the width of said curvilinear length (12) is less than or equal to 5 Lr.

Images