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), which are interspersed with a plurality of ribs arranged away from the axis of rotation (X-X) and provided with side walls adapted to define the side walls of said ventilation channels (5); each ventilation channel (5) extending along an extent direction between a radially inner air opening (6) and a radially outer air opening (7); said braking band (3) being provided with a continuous flat inner ring (10) having a median plane (M-M) and two side faces (8-9), on at least one of which there is a plurality of tower-shaped elements (13); each tower-shaped element (13) being arranged at a radially inner opening (10) of a ventilation channel (5), so as to completely overlap in the circumferential direction said radially inner opening and a first and a second rib, which are arranged adjacent to said radially inner opening, for more than 50% of their circumferential extent.

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] However, the Applicant noted that such coupling systems are often made in such a way as to adversely affect the cooling flows due to their conformation and / or location with respect to ventilation channels.

[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 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 would improve the coupling area between the brake bell and the braking band and would allow optimizing the ventilation of the brake disc.

[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 having side braking surfaces adapted to cooperate with a respective brake caliper and exerting a braking action on the vehicle on which the brake disc is installed; the side surfaces further defining a plurality of ventilation channels arranged away from the axis of rotation, which are interspersed with a plurality of ribs arranged away from the axis of rotation and provided with side walls adapted to define the side walls of said ventilation channels; each ventilation channel extending along an extent direction between a radially inner air opening and a radially outer air opening, the latter being arranged at the radially outer edge of the braking band;

[0014] -said braking band being provided with a continuous flat inner ring having a median plane and two side faces, on at least one of which there is a plurality of towershaped elements; each tower-shaped element being arranged at a radially inner opening of a ventilation channel, so as to completely overlap in the circumferential direction said radially inner opening and a first and a second rib, which are arranged adjacent to said radially inner opening, for more than 50% of their circumferential extent; each tower-shaped element being arranged at a radially inner opening of a ventilation channel, so as to completely overlap in the circumferential direction only one radially inner opening.

[0015] The opinion of the Applicant is that the presence of an opening placed directly behind a tower-shaped element allows, on the one hand, an overall increase in the number of ventilation channels on the brake disc and, on the other hand, an increase in the inlet section and, consequently, in the flow rate of the ventilation channels adjacent to the tower-shaped element and placed in the circumferential direction directly preceding and following the latter.

[0016] Thus, the Applicant has achieved a new optimization of the connection between brake bell and braking band, which allows improving the cooling air path at the inlet to the ventilation channels by increasing the flow of cooling air within the channels themselves.

[0017] For the purposes of the present invention, the following definitions apply:

[0018] "Axial direction" is defined as a direction substantially coincident with or substantially parallel to the axis of rotation of the brake disc.

[0019] By "radial direction" is meant a direction substantially orthogonal to the axial direction.

[0020] "Tangential or circumferential direction" means a direction orthogonal to both axial and radial directions.

[0021] 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°.

[0022] The present invention, in one or more preferred aspects, may comprise one or more of the following features.

[0023] Conveniently, the aforesaid tower-shaped element is arranged so as to overlap in the circumferential direction the aforesaid first and second ribs for at least 85% of their circumferential extent.

[0024] Preferably, the aforesaid tower-shaped element comprises a first substantially rectilinear side wall arranged on the prolongation of a side wall of the first rib and a second substantially rectilinear side wall arranged on the prolongation of a side wall of the second rib.

[0025] Conveniently, the aforesaid tower-shaped element may comprise a curvilinear side wall arranged to link the first and second substantially rectilinear side walls, the curvilinear side wall faces the axis of rotation.

[0026] Preferably, the curvilinear side wall has a radius of curvature greater than or equal to 5 mm.

[0027] Advantageously, the tower-shaped element extends in a direction parallel to the axis of rotation of the brake disc from one of the two side faces for a height less than or equal to 35 mm.

[0028] Conveniently, the aforesaid tower-shaped element extends, from a main plane containing the aforesaid radially inner opening, for a maximum of 40 mm in a direction inclined with respect to or coincident with the radial direction.

[0029] Preferably, the aforesaid radially inner opening arranged at each tower-shaped element extends for a height less than or equal to 18 mm in a direction which is parallel to the axis of rotation of the brake disc.

[0030] Advantageously, the radially inner opening arranged circumferentially after that at the aforesaid tower-shaped element extends from one of the two side faces for a height less than or equal to 30 mm and greater than or equal to 5 mm in a direction which is parallel to the axis of rotation of the brake disc.

[0031] Preferably, the radially inner opening arranged at each tower-shaped element has an area greater than or equal to 25 mm2.

[0032] Conveniently, each inner opening circumferentially consecutive and preceding the one arranged at each tower-shaped element has an area less than or equal to 500 mm 2.

[0033] Preferably, each inner opening arranged at each tower-shaped element has an area less than or equal to 0.9 of the area of the inner opening arranged in the circumferential direction.

[0034] Advantageously, the tower-shaped elements are made in one piece with the first and second ribs.

[0035] Preferably, each ventilation channel extends continuously along the extent direction between the radially inner air opening and the radially outer air opening.

[0036] Conveniently, two adjacent tower-shaped elements may be mutually placed at a distance, measured at two corresponding points, greater than or equal to 20 mm. Preferably, there may be eight to fourteen tower-shaped elements per brake disc.

[0037] 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.

[0038] Brief description of the drawings

[0039] This description will be set forth hereinafter with reference to the attached drawings provided for illustration purposes only and without limitation, in which:

[0040] - figure 1 shows a schematic perspective view of a braking band of a first embodiment of the brake disc according to the invention;

[0041] - figure 2 is a sectional side view of a portion of the braking band of figure 1;

[0042] - figure 3 is a schematic sectional view of the braking band taken along the E-E sectional plane of figure 2;

[0043] - figure 4 is a schematic, enlarged, perspective view of the portion of the brake disc at a tower-shaped element according to the present invention; and

[0044] - figure 5 is a schematic, enlarged, plan and sectional view of a portion of the brake disc at a tower-shaped element according to the present invention.

[0045] Detailed description of embodiments of the invention

[0046] With reference to the attached figures, a brake disc according to the present invention is generally denoted by 1.

[0047] The brake disc 1 comprises and is constituted by a metal brake bell 2 and a braking band 3 radially outside the latter.

[0048] The metal brake bell 2 and the braking band 3 extend around a common central axis of rotation denoted by X-X.

[0049] 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. 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.

[0050] Between the two side surfaces 4 belonging to the braking band 3 a plurality of ventilation channels 5 are defined and formed, which are arranged away from the axis of rotation X-X and interspersed with a plurality of ribs 15 also arranged away from the axis of rotation X-X.

[0051] Each rib 15 has, in plan, a width L and side walls 15', 15" arranged so as to define the side walls 5’, 5” of the aforesaid ventilation channels 5.

[0052] The side walls 15’, 15” of the aforesaid ribs 15 extend away from the axis of rotation X-X for the entire extent of the ventilation channels 5.

[0053] Preferably, the ribs 15 do not have a constant width, in plan, along their extent direction, but they have a width increasing away from the axis of rotation X-X.

[0054] By width of a rib 15 is meant a dimension of the rib 15 substantially orthogonal to the extent direction of the rib itself.

[0055] The ventilation channels 5 extend away from the axis of rotation X-X in an extent direction, between a radially inner air opening 6 facing the axis of rotation X-X, and a radially outer air opening 7 arranged at the radially outer edge of the braking band 3. Each ventilation channel 5 extends continuously away from the axis of rotation X-X along the extent direction, between the radially inner air opening 6 and the radially outer air opening 7.

[0056] Thus, the side walls 15’ 15” of the aforesaid ribs 15 extend continuously away from the axis of rotation X-X, that is, without having interruptions altogether greater than or equal to 10% of their extent measured along their extent direction.

[0057] Preferably, the ventilation channels 5 do not have constant cross-section, along their extent direction, but a cross-section that increases away from the axis of rotation X-X.

[0058] 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. The side walls 5 ’,5’ of the ventilation channels 5, in plan, are directed substantially in accordance with the extent direction of the ventilation channel or slightly inclined with respect to it.

[0059] The side walls 5 ’,5’ of the ventilation channels 5 are coincident with the side walls 15’, 15’ of the ribs 15, in other words, as previously mentioned, the side walls 15’, 15’ of the ribs 15 define and are coincident with the side walls 5 ’,5’ of the ventilation channels 5.

[0060] In the embodiment shown in the figures, each ventilation channel 5 has, in plan, a course provided with a rectilinear length 11 and a curvilinear length 12 arranged consecutively to the rectilinear length 11, but they could have a different course, such as substantially rectilinear for the entire extent of the ventilation channel 5 itself, without departing from the scope of protection of the present invention.

[0061] Still referring to the embodiment shown in the figures, the rectilinear length 11 extends from the radially inner opening 6 and, having an extent greater than the curvilinear length 12, the latter flows into the radially outer air opening 7, as can be seen in figure 3.

[0062] Still referring to the embodiment shown in the figures, 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.

[0063] Preferably, the rectilinear length 11 has an extent greater than or equal to 60% 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.

[0064] 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.

[0065] Preferably, the rectilinear length 11 has a course inclined with respect to the radial direction, so as to form an angle of inclination a greater than or equal to 45°.

[0066] Preferably, each radially inner opening 6 has an area greater than or equal to 36 mm 2.

[0067] As will be described in more detail below, not all the radially inner openings 6 have the same area. Referring to the embodiment shown in the figures, in the circumferential direction two circumferentially consecutive radially inner openings 6 are interspersed with a radially inner opening 6 with reduced area.

[0068] The reduction of the reduced area in that radially inner opening 6 is due to the particular conformation of a tower-shaped element 13 described below, arranged at, in particular in front of, that radially inner opening 6.

[0069] Each radially inner opening 6 circumferentially consecutive and preceding the one arranged at the tower-shaped element 13, that is, the one with the reduced area, instead has an area that is not reduced but still less than or equal to 500 mm2.

[0070] The radially inner opening 6 arranged at each tower-shaped element 13, that is, the one with the reduced area, has an area less than 0.9 of the area of the circumferentially consecutive radially inner opening 6. The same applies to the radially inner air opening 6 preceding that arranged at each tower-shaped element 13.

[0071] The radially inner opening 6 arranged at each tower-shaped element 13 extends for a height H less than or equal to 18 mm in a direction which is parallel to the axis of rotation X-X of the brake disc 1.

[0072] The height of this radially inner opening 6 is measured from a top surface of the tower-shaped element 13.

[0073] On the other hand, the radially inner opening 6 arranged circumferentially consecutive or preceding that at the aforesaid tower-shaped element 13 has a height H less than or equal to 30 mm and greater than or equal to 5 mm, measured along a direction parallel to the axis of rotation X-X.

[0074] Each radially outer opening 7 has an area greater than or equal to the area of the radially inner opening 6.

[0075] The radially outer openings 7 may all have the same area.

[0076] 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.

[0077] 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.

[0078] The inner ring 10 may have at least one tower-shaped element 13 that runs substantially orthogonally to the median plane M-M from a side face 8 of the inner ring 10.

[0079] 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 tower-shaped elements 13 distributed along a coupling circumference 20 concentric to the central axis of rotation X-X.

[0080] The tower-shaped elements 13 provide a seat 27 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.

[0081] The tower-shaped elements 13 are spaced angularly, preferably consistently along the coupling circumference 20.

[0082] Preferably, the tower-shaped elements 13 are mutually placed at a distance, measured at two corresponding points on two adjacent tower-shaped elements 13, greater than or equal to 20 mm, preferably greater than or equal to 40 mm.

[0083] The tower-shaped elements 13 are mutually placed at a distance, measured at two corresponding points on two adjacent tower-shaped elements 13, less than or equal to 80 mm.

[0084] Preferably, there are eight to fourteen tower-shaped elements 13 per brake disc 1, even more preferably there are nine to thirteen tower-shaped elements 13 per brake disc 1.

[0085] Advantageously, each tower-shaped element 13 extends in a direction which is parallel to said axis of rotation X-X from one of the two side faces 8,9 for a height less than or equal to 35 mm.

[0086] Each tower-shaped element 13 is arranged at a radially inner opening 6 of a ventilation channel 5, so as to completely overlap in the circumferential direction that radially inner opening 6 and to overlap a first and a second rib 15, which are arranged adjacent to that radially inner opening, for more than 50% of their circumferential extent.

[0087] In other words, each tower-shaped element 13 completely overlaps a radially inner opening 6 and predominantly, almost completely, the two ribs 18, said first and second ribs, adjacent to the aforesaid radially inner opening 6.

[0088] Preferably, each tower-shaped element 13 is arranged so as to overlap in the circumferential direction the first and second ribs for at least 85% of their circumferential extent.

[0089] Each tower-shaped element 13 is arranged at a radially inner opening 6 of a ventilation channel 5, so as to completely overlap in the circumferential direction only one radially inner opening 6.

[0090] In other words, each tower-shaped element 13 does not affect more than two adjacent ribs 15 in the circumferential direction and the radially inner opening 6 interposed between them in the circumferential direction.

[0091] In the embodiment shown in the figures, two consecutive ribs 15 in the circumferential direction, so-called first and second ribs, are joined together by a tower-shaped element 13 that has substantially the same height for its entire extent, thus reducing the inlet area of the radially inner opening 6 located in the radial direction behind the tower-shaped element 13 itself.

[0092] In contrast, the two radially inner openings 6 adjacent in the circumferential direction to the one with reduced inlet area do not show a section reduction.

[0093] As a result, each radially inner opening 6 arranged at each tower-shaped element 13 has an area less than 0.9 of the area of the circumferentially following and preceding radially inner openings.

[0094] In the following we will describe a tower-shaped element 13, its shape and arrangement with respect to three radially inner openings 6 consecutive in the circumferential direction and interspersed with two ribs 15, named first and second ribs, as for example shown in figure 4, it being understood that the above applies to all remaining tower-shaped elements 13. Each tower-shaped element 13 comprises a first substantially rectilinear side wall 16 arranged on the prolongation of a side wall 15’ of the first rib and a second substantially rectilinear side wall 17 arranged on the prolongation of a side wall 15” of the second rib.

[0095] As best seen in figure 3, the first 16 and second 17 substantially rectilinear side walls are joined and linked to each other by a curvilinear side wall 18 that faces the axis of rotation X-X.

[0096] The curvilinear side wall 18 has a radius of curvature R greater than or equal to 5 mm.

[0097] Each tower-shaped element 13 has, in plan, an elongated shape in a direction adapted to form an angle of inclination p with a radial direction.

[0098] As visible in figure 3, each tower-shaped element 13 extends in that direction from a main plane containing predominantly, that is, for at least 50% of its extent, the radially inner opening 6.

[0099] Preferably, each tower-shaped element 13 extends a maximum of 40 mm in that direction.

[0100] According to an alternative embodiment, each tower-shaped element 13 has an elongated shape, in plan, in a direction coinciding with a radial direction.

[0101] Each tower-shaped element 13 extends in that direction from a main plane containing predominantly, that is, for at least 50% of its extent, the radially inner opening 6.

[0102] Preferably, each tower-shaped element 13 extends a maximum of 40 mm in that direction.

[0103] Preferably, the tower-shaped elements 13 are made in one piece with the brake plate 3.

[0104] Advantageously, all tower-shaped elements 13 of the same brake disc are equal in shape and size.

[0105] 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: - better cooling efficiency of the braking band 3 and brake disc 1 is allowed, compared with known solutions;

[0106] - the path of cooling air entering the ventilation channels is optimized so as to increase the flow of cooling air within the channels themselves; - mechanical and thermo-mechanical stresses on the braking surfaces of the braking band are reduced;

[0107] - disk life in terms of vehicle mileage is increased, particularly for applications on high-performance vehicles, such as race cars.

[0108] 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 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), which are interspersed with a plurality of ribs (15) arranged away from the axis of rotation (X-X) and provided with side walls (15', 15") adapted to define, in plan, the side walls (5', 5") of said ventilation channels (5); each ventilation channel (5) extending along an extent direction between a radially inner air opening (6) and a radially outer air opening (7), the latter being arranged at the radially outer edge of the braking band (3); said braking band (3) being provided with a continuous flat inner ring (10) having a median plane (M-M) and two side faces (8-9), on at least one of which there is a plurality of tower-shaped elements (13); each tower-shaped element (13) being arranged at a radially inner opening (6) of a ventilation channel (5), so as to completely overlap in the circumferential direction said radially inner opening (6) and a first and a second rib (15), which are arranged adjacent to said radially inner opening (6), for more than 50% of their extent in the circumferential direction, each towershaped element (13) being arranged at a radially inner opening (6) of a ventilation channel (5), so as to completely overlap in the circumferential direction only one radially inner opening (6).

2. Brake disc (1) according to claim 1, characterized in that said tower-shaped element (13) is arranged so as to overlap said first and second ribs (15) in the circumferential direction for at least 85% of their extent in the circumferential direction.

3. Brake disc (1) according to claim 1 or 2, characterized in thatsaid tower-shaped element (13) comprises a first substantially rectilinear side wall (16) arranged on the prolongation of a side wall (15') of said first rib and a second substantially rectilinear side wall (17) arranged on the prolongation of a side wall (15") of said second rib (15).

4. Brake disc (1) according to claim 3, characterized in that said tower-shaped element (13) comprises a curvilinear side wall (18) arranged to link said first (16) and said second (17) substantially rectilinear side walls, said substantially curvilinear side wall (18) facing said axis of rotation (X-X).

5. Brake disc (1) according to any one of claims 1 to 4, characterized in that said tower-shaped element (13) extends in a direction which is parallel to said axis of rotation (X-X) from one of the two side faces (8-9) for a height less than or equal to 35 mm.

6. Brake disc (1) according to any one of claims 1 to 5, characterized in that said tower-shaped element (13) extends, from a main plane containing said radially inner opening (6), for a maximum of 40 mm in a direction inclined with respect or coincident with the radial direction.

7. Brake disc (1) according to any one of claims 1 to 6, characterized in that said radially inner opening (6) arranged at each towershaped element (13) extends for a height (H) less than or equal to 18 mm in a direction which is parallel to the axis of rotation of the brake disc (1).

8. Brake disc (1) according to any one of claims 1 to 7, characterized in that said radially inner opening (6) arranged circumferentially after that at said tower-shaped element (13) extends from one of the two side faces (8-9) for a height (H) less than or equal to 30 mm and greater than or equal to 5 mm in a direction which is parallel to the axis of rotation (X-X) of the brake disc (1).

9. Brake disc (1) according to any one of claims 1 to 8, characterized in that said radially inner opening (6) arranged at each towershaped element (13) has an area greater than or equal to 25 mm2.

10. Brake disc (1) according to any one of claims 1 to 9,characterized in that said each radially inner opening, which is circumferentially successive to that arranged at the tower-shaped element (13), has an area less than or equal to 500 mm2.

11. Brake disc (1) according to any one of claims 1 to 10, characterized in that said radially inner opening (6) arranged at each towershaped element (13) has an area 0.9 less than the area of the successive or previous inner opening in the circumferential direction.

12. Brake disc (1) according to any one of preceding claims 1 to 11, characterized in that said tower-shaped elements (13) are made in one piece with said first and second ribs (18).

13. Brake disc (1) according to any one of preceding claims 1 to 12, characterized in that each ventilation channel (5) extends continuously along the extent direction between said radially inner air opening (6) and said radially outer air opening (7).

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