Floating brake disc for bicycles

Abstract

The object of the present invention is a brake disc (1) of a disc brake (2) comprising a braking band (3); a bell (4); wherein said braking band (3) comprises braking band arms (5); said braking band arms (5) comprise braking band arm through-holes (6); said bell (4) comprises bell connection seats (7); said bell connection seats (7) comprise bell through-holes (11); wherein said braking band arm through-holes (6) face, along an axial direction (A-A), said bell through-holes (11); into each pair of mutually facing braking band arm through-hole (6) and bell through-hole (11) a connection element (12) is inserted; said connection element (12) forms, when the brake disc (1) is not in a braking condition, a clearance or void (13) with said braking band arm through-hole (6) and with said bell through-hole (11); said connection element (12) delimits the relative displacement between said braking band (3) and said bell (4).

Description

Floating brake disc for bicycles★ ★ ★DESCRIPTION

[0001] . Field of the invention

[0002] . The present invention relates to a disc brake of a floating-type disc brake.

[0003] . In particular, the present invention relates to a disc brake of a floating disc brake for bicycles.

[0004] . Furthermore, this invention relates to a brake disc for bicycles suitable for improving the distribution of mechanical stresses between the braking band and the bell, reducing plastic deformations during braking and optimising the load transfer between the components.

[0005] . Prior art

[0006] . In a disc brake, the brake calliper is generally arranged straddling the outer peripheral edge of a brake disc, suitable for rotating about a rotation axis (X-X) defining an axial direction (A-A). In a disc brake, a radial direction (R-R), substantially orthogonal to said rotation axis (X-X), and a tangential (C-C) or circumferential (C-C) direction, orthogonal both to said axial direction (A-A) and to said radial direction (R-R), are also defined.

[0007] . The brake callipers are constrained to a support structure that remains stationary with respect to the wheel of the vehicle, such as for example a spindle of a vehicle suspension or a wheel hub of a vehicle or a fork. The brake calliper generally comprises acalliper body having two elongated portions arranged so as to face opposite braking surfaces of a brake disc, and at least one bridge connecting said two elongated portions. The appropriately actuated callipers press the pads against the braking band, and the braking action is produced by the friction between the pads and the braking band of the brake disc.

[0008] . Brake discs are known in which the bell is made of a material different from that of the braking band, and in particular bells made of steel sheet and provided with seats to house a circumferential coupling toothing of the braking band.

[0009] . Such brake discs, which may be called composite, allow, for example, a lower weight and thus help reduce the weight of the unsprung masses of the related vehicle.

[0010] . Various patent documents exist which describe floating discs for bicycle disc brakes.

[0011] . For example, patent document EP3269624 describes a brake disc for bicycles having a predetermined rotation axis and comprising: - a first component made of a first material and having a braking track configured to cooperate with brake pads; - a second component made of a second material and having a radially inner annular portion for coupling with a hub of a bicycle wheel and a plurality of radially outer portions for connection to said first component at a respective plurality of connection portions of said first component. The first component comprises a plurality of connecting arms extending from said braking track towards said predetermined rotation axis and which are distinct from saidplurality of connection portions, wherein at least one of said connecting arms of said first component and at least one of said radially outer connection portions of said second component are coupled to each other by at least one form-fitting coupling.

[0012] . Furthermore, document EP3441295 describes a brake disc for bicycles comprising a support having a connection portion configured for connection to a hub of a bicycle wheel rotatable about a rotation axis and a plurality of coupling seats, a rotor comprising a radially outer braking track and a plurality of radially inner coupling seats which at least partially axially overlap the coupling seats of the support to define connection areas, wherein said rotor and said support are joined together by mechanical j oints active in said connection areas. The constraint between at least one coupling seat of the rotor and a coupling seat of the support in a respective connection area has a degree of freedom of translation.

[0013] . Document CN104976252B describes a floating disc comprising a ring-shaped outer disc body, an inner disc body and a plurality of combination groups. A plurality of first assembly parts is arranged on the inner side of the outer ring-shaped disc body. A plurality of second assembly parts is arranged on the outer circumference of the inner disc body. Each combination group comprises a fixing and combination column and an insertion and support piece. Each insertion and support piece is provided with an assembly hole. Each insertion and support piece is provided with a plurality of limiting pieces at the inner edge of the hole of the corresponding assembly hole, and the limiting pieces extend towards the centre of theassembly hole. The fixing and combination columns penetrate through the first assembly parts of the outer ring-shaped disc body, the second assembly parts of the inner disc body and the assembly holes. The limiting elements extend obliquely in the direction in which the fixing and combination columns penetrate through the assembly holes and are forced to abut against the outer circumferences of the fixing and combination columns. The fixing and combination columns of the combination groups penetrate through the outer ring-shaped disc body and the inner disc body, so that the outer ring-shaped disc body and the inner disc body are combined. The insertion and support pieces penetrate through the rear ends of the fixing and combination columns, so that the limiting pieces of the insertion and support pieces are made to abut against the fixing and combination columns, and a combined positioning effect is obtained.

[0014] . Document EP2821664 describes a brake disc capable of improving the steering performance of a motorcycle by reducing inertia and preventing deposit on a braking portion by reducing a temperature variation of the braking portion. A brake disc is provided with a sliding disc, a hub disc and a connection pin to connect the discs together in multiple positions in the circumferential direction of the brake disc. A convex engagement portion proj ecting inward from the sliding disc is formed on the sliding disc in circumferential positions corresponding to the connection pins. A concave engagement portion to receive the convex engagement portion is formed in the outer periphery of the hub disc. An insertion hole for the connection pin is formed in the convexengagement portion.

[0015] . Furthermore, patent document CN110878799 describes a floating disc composed of an inner disc, an outer disc and a plurality of rivets. The inner disc is a support structure proj ecting from a fixed connection part that forms the disc-type support, a groove is formed in the outer edge of the support structure in a concave manner, and the groove is provided with a communication screw hole. The inner edge of the outer disc extends to form an extending flange, the extending flange can be arranged in the groove and the extending flange is provided with an elongated hole; the rivets penetrate the elongated hole of the extending flange through a large-diameter part and are fixed in a threaded manner to the screw hole of the support structure through a small-diameter threaded part, and thus two lines of intersection on the diameter of the large-diameter part and the elongated hole are supported in a point-to-point support mode. Meanwhile, each surface of the extending flange is separated from each surface of the groove without contact, so that the thermal conductivity coefficient of the rivets and of the outer disc is reduced.

[0016] . However, the known art documents described do not provide a specific sizing and coupling geometry of the bell connection seats designed to house in overlapping arrangement the fastening portions of the braking band, in order to optimise the load distribution between the two parts of the brake disc, namely the bell and the braking band, so as to avoid excessive plastic deformation of the bell during the braking step.

[0017] . Technical problem

[0018] . One of the technical problems that the present invention aims to solve is to improve the distribution of mechanical stresses, specifically the load transfer, between the interface surfaces of the bell and the braking band of a floating disc for a bicycle disc brake during a braking action, so as to ensure a reduced plastic deformation of the floating disc itself.

[0019] . Solution

[0020] . The purpose of the present invention is therefore to provide a disc brake of a disc brake including a toothed connection between a bell and a braking band.

[0021] . This and other aims and advantages are achieved with a brake disc according to claim 1.

[0022] . Some advantageous embodiments are the subj ect of the dependent claims.

[0023] . In accordance with a general embodiment, a disc brake of a disc brake is composed of a braking band and a bell or connection element to a wheel hub. The braking band rotates about a rotation axis, defining axial, radial and circumferential directions. The bell, connected to the wheel hub, is provided with connection seats comprising through-holes for inserting connection elements, such as rivets. These holes are aligned with through-holes present in the arms of the braking band. When the brake disc is not in a braking condition, there is a clearance or void between the connection elements and the holes, allowing a certain relative movement between the braking band and the bell.

[0024] . This design ensures that the connection elements are subj ect only to axial stresses, avoiding bending or shear stresses, and allowing a direct load transfer from the braking band to the bell through the walls of the connection seats and the arms of the braking band. The clearance between the connection elements and the respective seats is greater than that between the arms of the braking band and the bell seats, facilitating radial and circumferential movement of the connection elements during the thermal stresses caused by braking.

[0025] . Furthermore, some embodiments provide that the support walls of the arms and the connection seats are parallel and inclined, to improve manufacturing and tolerance control. In this way, the stress distribution is optimised and plastic deformation of the bell is reduced, improving the safety and performance of the brake disc.

[0026] . A feature present in the bell connection seats is the lead-in surface. This surface is provided to facilitate alignment and insertion of the braking band arms into the respective seats. The lead-in surface forms an enlargement in the connection seat, which can be inclined with respect to the radial or circumferential direction. This enlargement ensures a smooth and controlled insertion of the arms, improving the assembly and operation of the brake disc, while reducing the mechanical stress in the radially outer area of the connection seat and thus improving the load distribution during braking operations.

[0027] . In accordance with one embodiment, a brake disc isdescribed in which the clearance between the connection element and the through-holes of the arms and seats is greater than the clearance between the connecting arms and the respective connection seats, in order to ensure the radial and circumferential flotation of the braking band with respect to the bell.

[0028] . In accordance with one embodiment, a brake disc is described in which each connection seat is delimited by opposed walls that delimit the seat at least in the circumferential direction and by a bottom wall in the axial direction, forming a channel-like structure.

[0029] . In accordance with one embodiment, a brake disc is described in which each of the opposed walls of the connection seat comprises parallel segments forming an acute angle with respect to the radial direction and oriented away from the rotation axis, facilitating the manufacture of the connection seats and the control of construction tolerances.

[0030] . In accordance with one embodiment, a brake disc is described in which between the through-hole of the connecting arms and the connection element an elastic element is inserted, such as a cup spring, which constantly presses the braking band against the bell.

[0031] . In accordance with one embodiment, a brake disc is described in which the dimensions of the connection seats and the connecting arms are such that the width of the connection seat is greater than the width of the connecting arm; the distance between the centre of the through-hole of the connection seat and theinterface surface of the seat is greater than the corresponding distance on the connecting arm; the diameter of the through-hole of the connection seat is greater than the diameter of the through-hole of the connecting arm, which in turn is greater than the diameter of the connection element, ensuring correct clearance and flotation during thermal stresses.

[0032] . In accordance with one embodiment, the diameter of the bell through-hole (Ø1) is greater than the diameter of the connection element (Ø3), which in turn is greater than the diameter of the braking band arm through-hole (Ø2), ensuring proper clearance and flotation (i.e. free movement) during thermal stresses.

[0033] . In accordance with one embodiment, a brake disc is described in which the depth of the connection seat coincides with the thickness of the connecting arm, optimising the load transfer and ensuring uniform stress distribution during braking actions.

[0034] . Figures

[0035] . Further features and advantages of the device, the disc brake and the vehicle will become apparent from the following description of preferred embodiments, given by way of non-limiting example, with reference to the accompanying figures in which:

[0036] . - Figure 1 illustrates a disc brake of a disc brake in an axonometric view from the vehicle outer side;

[0037] . - Figure 2 shows the disc of Figure 1 in an axonometric view from the wheel side;

[0038] . - Figure 3 shows a front view of the brake disc of Figure 1 from the outer side;

[0039] . - Figure 4 shows in front view a detail of the brake disc of Figure 3;

[0040] . - Figure 5 shows in front view the brake disc of Figure 2 from the wheel side;

[0041] . - Figure 6 shows in front view a detail of the brake disc of Figure 5 from the wheel side;

[0042] . - Figure 7 shows in a side sectional view, along a plane containing the radial direction R-R and axial direction A-A passing through the rotation axis X-X, a section of the brake disc of Figure 1;

[0043] . - Figure 8 shows in section a detail of Figure 7 highlighting the coupling between the braking band and the bell;

[0044] . - Figure 9 shows in a sectioned axonometric view the detail of Figure 8 from the outer side;

[0045] . - Figure 10 shows in a sectioned axonometric view the detail of Figure 8 from the wheel side;

[0046] . - Figure 11 shows in exploded axonometric view the brake disc of Figure 1;

[0047] . - Figure 12 shows in axonometric view from the outer side the bell of the brake disc of Figure 1;

[0048] . - Figure 13 shows in front view a detail of the bell of Figure 12 and in particular the bell connection seat according to a first embodiment;

[0049] . - Figure 14 shows in axonometric view the detail of Figure 13;

[0050] . - Figure 15 shows in front view a detail of the bell andin particular the bell connection seat according to a second embodiment;

[0051] . - Figure 16 shows in axonometric view the detail of Figure 15;

[0052] . - Figures 17 to 19 show a specific section of the brake disc of Figure 1, sectioned along a plane containing the radial direction R-R and circumferential direction C-C, showing the coupling between the braking band and the bell in a vehicle stationary state, during forward braking and reverse braking, according to the first embodiment;

[0053] . - Figures 20 to 22 show a specific section of the bell and the connection element or rivet of the brake disc of Figure 1, sectioned along a plane containing the radial direction R-R and circumferential direction C-C, showing the connection element and bell in a vehicle stationary state, during forward braking and reverse braking, according to the first embodiment;

[0054] , - Figures 23 to 25 show a specific section of the brake disc of Figure 1, sectioned along a plane containing the radial direction R-R and circumferential direction C-C, showing the coupling between the braking band and the bell in a vehicle stationary state, during forward braking and reverse braking, according to the second embodiment;

[0055] . - Figures 26 to 28 show a specific section of the bell and the connection element or rivet of the brake disc of Figure 1, sectioned along a plane containing the radial direction R-R and circumferential direction C-C, showing the connection element andbell in a vehicle stationary state, during forward braking and reverse braking, according to the second embodiment;

[0056] . - Figure 29 shows in axonometric view a disc brake comprising a brake disc and a brake calliper straddling its braking band.

[0057] . Description of some preferred embodiments

[0058] . In accordance with a general embodiment, a brake disc 1 of a disc brake 2 comprises a braking band 3.

[0059] . Said braking band has a band 3 body suitable for rotating about a rotation axis X-X defining axial directions A-A coinciding with or parallel to said rotation axis X-X, radial directions R-R orthogonal to said rotation axis X-X, and circumferential directions C-C each orthogonal to one of said axial directions A-A and one of said radial directions R-R at their point of intersection.

[0060] . Said brake disc 1 of disc brake 2 comprises a bell 4, or a connection element to a wheel hub.

[0061] . Said braking band 3 comprises braking band arms 5.

[0062] . Said braking band arms 5 comprise through-holes of the braking band arm 6.

[0063] . Said bell 4 comprises bell connection seats 7.

[0064] . Said bell connection seats 7 comprise bell through-holes 11.

[0065] . Said through-holes of the braking band arm 6 face, along an axial direction A-A, said bell through-holes 11.

[0066] . In each pair of mutually facing through-hole of the braking band arm 6 and bell through-hole 11, a connection element 12is inserted. Said connection element 12 is for example, but not necessarily, a rivet.

[0067] . Said connection element 12 forms, when the brake disc 1 is not in a braking condition, a clearance or void 13 with said through-hole of the braking band arm 6 and with said bell through-hole 11.

[0068] . Said connection element 12 delimits the relative displacement between said braking band 3 and said bell 4.

[0069] . Thanks to these generally described embodiments, it is possible to have a connection element that never undergoes bending or shear stresses, but only axial stresses even during braking actions in forward or reverse motion (as represented in Figures 18, 19 and 21, 22 or, in another embodiment, in Figures 24, 25 and 27, 28 ).

[0070] . Thanks to these generally described embodiments, and in accordance with an embodiment, the load is transferred directly from the braking band 3 to the bell 4, for example through seat walls 8, 9 and arm support walls 14, 15 of the bell connection seats 7 and respectively of the braking band arms 5.

[0071] . The clearance 13 provided between the connection element 12 or rivet and the bell through-hole 11 must be greater than the clearance provided between the braking band arms 5 and the respective bell connection seats 7, thereby ensuring radial and circumferential movement (or flotation) of the connection elements 12 or rivets, isolating them from tangential load transfer during the braking action.

[0072] . In accordance with an embodiment, the through-holes of the braking band arm 6 are of smaller size than the bell through-holes 11.

[0073] . In accordance with an embodiment, the clearance 13 between the connection element 12 and each of the through-holes of the braking band arm 6 is less than the clearance 13 between the connection element 12 and each of the bell through-holes 11.

[0074] . Thanks to the provided solutions, the tangential braking load is transmitted from the braking band 3 to the bell 4 through the contact of the braking band arms 5 with the bell connection seats 7.

[0075] . Furthermore, the provided clearance allows the radial expansion of the braking band 3 during the thermal stresses caused by the braking actions of the disc brake 2, avoiding mechanical stressing of said bell 4.

[0076] . In accordance with a non-essential embodiment, said braking band arms 5 extend in a plane containing a radial direction R-R and a circumferential direction C-C towards said rotation axis X-X.

[0077] . In accordance with a non-essential embodiment, said braking band arms 5 comprise opposite arm support walls 14, 15, which form support surfaces at least in the circumferential direction C-C.

[0078] . For example, said arm support walls 14, 15 contrast movement in the circumferential direction C-C, and, again by way of example, lie in planes containing a radial direction R-R and an axial direction A-A.

[0079] . In accordance with a non-essential embodiment, said opposite arm support walls 14, 15 comprise at least mutually parallel segments.

[0080] . In accordance with a non-essential embodiment, said opposite arm support walls 14, 15 comprise at least mutually parallel segments which open an acute angle Alfa1 with respect to a radial direction R-R and in an orientation away from said rotation axis X-X.

[0081] . Thanks to the parallel and inclined segments, it is possible to achieve easier manufacturing of the bell connection seats 7 and greater control of construction and coupling tolerances between the braking band arms 5 and said bell connection seats 7, thus better control of the support between braking band 3 and bell 4 and therefore better functioning of the band-to-bell coupling.

[0082] . In accordance with a non-essential embodiment, each of said bell connection seats 7 is delimited by opposed seat walls 8, 9 which delimit said bell connection seat 7 at least in the circumferential direction C-C, and by a seat bottom wall 10 which delimits said bell connection seat 7 in the axial direction A-A, such that said bell connection seat 7 has a channel shape.

[0083] . In accordance with a non-essential embodiment, between said opposed seat walls 8, 9 and said seat bottom wall 10 a discharge channel 32 is provided, suitable for ensuring that during the braking action said braking band arm 5 fully abuts with its arm support wall 14 or 15, depending on the forward or reverse motion of the vehicle on which said disc brake 2 is mounted, against said seatwall 8 or 9.

[0084] . In accordance with a non-essential embodiment, said seat walls 8, 9 are connected to said seat bottom wall 10 through a discharge channel 32 suitable for allowing a complete and secure support between said arm support wall 14 or 15 and said seat wall 8 or 9.

[0085] . In accordance with a non-essential embodiment, said opposed seat walls 8, 9 comprise at least mutually parallel segments.

[0086] . In accordance with a non-essential embodiment, said opposed seat walls 8, 9 comprise at least mutually parallel segments which open an acute angle Alfa2 with respect to a radial direction R-R and in an orientation away from said rotation axis X-X.

[0087] . In accordance with a non-essential embodiment, said braking band arms 5 are housed in said bell connection seats 7.

[0088] . In accordance with a non-essential embodiment, said braking band arms 5 are housed in said bell connection seats 7 leaving a clearance between them, when said brake disc 1 is not in a braking condition, in the circumferential C-C and radial R-R directions.

[0089] . In accordance with a non-essential embodiment, said braking band arms 5 are housed in said bell connection seats 7. Each of said opposite arm support walls 14, 15 comprises at least one portion directly facing at least one portion of said opposed seat walls 8, 9.

[0090] . When said brake disc 1 is not in a braking condition, between each of said at least one portion of each of said oppositearm support walls 14, 15 and the respective facing portion of said opposed seat walls 8, 9, there is a clearance in the circumferential C-C and radial R-R directions.

[0091] . In accordance with a non-essential embodiment, said connection element 12 comprises a connection element head 16, a connection element shank 17, and an enlarged riveting portion 18.

[0092] . Said connection element head 16 comprises a head crossdimension 19 greater than the cross-dimension of said bell through-holes 11 and / or said braking band arm through-holes 6 and is suitable for counteracting relative axial displacements between the bell 4 and the braking band 3.

[0093] . After coupling, therefore after riveting, said enlarged riveting portion 18 comprises a riveting cross-dimension 20 greater than the cross-dimension of said braking band arm through-holes 6 and / or said bell through-holes 11 and is suitable for counteracting relative axial displacements between the braking band 3 and the bell 4.

[0094] . After coupling, therefore after riveting, the axial extension of said connection element shank 17 is greater than the thickness dimension of said braking band 3 placed beside said bell 4, allowing a relative, controlled axial sliding of said braking band 3 with respect to said bell 4.

[0095] . In accordance with a non-essential embodiment, after coupling, the axial extension of said connection element 12 is greater than the thickness dimension of said braking band 3 placed beside said bell 4, allowing a relative, controlled axial sliding ofsaid braking band 3 with respect to said bell 4.

[0096] . Between said connection element 12 and said bell 4 or said braking band 3, an elastic element 21 is interposed which constantly biases said braking band 3 against said bell 4, either directly or through said connection element 12.

[0097] . In accordance with a non-essential embodiment, said elastic element is a cup spring 21, for example a slotted or petal-shaped cup spring.

[0098] . In accordance with a non-essential embodiment, said connection element 12 or rivet clamps the braking band in a stack. For example, the shank of said connection element 17 comprises two segments of different cross-extension, so as to form a shank abutment surface 22 on which to abut the braking band 3 and lock said braking band 3 in a stack between said enlarged riveting portion 18 and said shank abutment surface 22.

[0099] . In accordance with a non-essential embodiment, receiving seats for the enlarged riveting portion 23 are provided around said braking band arm through-holes 6, so as to house said enlarged riveting portion 18 completely within said seat and prevent it from axially protruding.

[0100] . In accordance with a non-essential embodiment, said connection element head 16 comprises a discharge channel 24 in the junction portion with the connection element shank, in order to ensure the full abutment of the entire head of the connection element 16 against the bell 4 or the braking band 3.

[0101] . In accordance with a non-essential embodiment, each brakingband arm 5 comprises an inner radial arm plane 25, which extends in a plane comprising an axial direction A-A; said inner radial arm plane 25 is flat in shape and faces a radial seat plane 26, which connects to seat walls 8, 9 and is also flat in shape, leaving a clearance between said inner radial arm plane 25 and said radial seat plane 26.

[0102] . In accordance with a non-essential embodiment, said radial seat plane 26 and said inner radial arm plane 25 allow easier manufacturing and greater control of the radial clearance between braking band 3 and bell 4.

[0103] . In accordance with a non-essential embodiment, said bell connection seat 7 comprises a lead-in surface 27.

[0104] . In accordance with a non-essential embodiment, said bell connection seat 7 comprises a lead-in surface 27 which forms an enlargement of said bell connection seat 7 in the circumferential C-C and / or radial direction R-R compared to the remaining width of said bell connection seat 7.

[0105] . In accordance with a non-essential embodiment, the widest portion of the bell connection seat 7 is provided at the radial entry end of said seat 7 wherein said lead-in surface 27 is present.

[0106] . In accordance with a non-essential embodiment, said bell connection seat 7 comprises a lead-in surface 27 placed at the outer radial mouth of said bell connection seat 7.

[0107] . In accordance with a non-essential embodiment, said bell connection seat 7 comprises a lead-in surface 27; said lead-in surface 27 comprises at least one segment of lead-in surface 28 offlat shape.

[0108] . In accordance with a non-essential embodiment, said bell connection seat 7 comprises a lead-in surface 27; said lead-in surface 27 comprises at least one flat lead-in surface segment 28 with a predetermined inclination with respect to said radial direction R-R, or a predetermined inclination Beta with respect to the extension direction of the bell connection seat 7, or a predetermined inclination Beta with respect to the extension direction of the seat wall 8 of said bell connection seat 7 to which said lead-in surface 27 connects.

[0109] . In accordance with a non-essential embodiment, said bell connection seat 7 comprises a lead-in surface 27; said lead-in surface 27 comprises at least one flat lead-in surface segment 28 with a predetermined inclination with respect to said radial direction R-R, or a predetermined inclination Beta with respect to the extension direction of the bell connection seat 7, or a predetermined inclination Beta with respect to the extension direction of the seat wall 8 of said bell connection seat 7 to which said lead-in surface 27 connects by means of a wide connection segment 29.

[0110] . In accordance with a non-essential embodiment, thanks to said lead-in surface, the clearance between the braking band arms 5 and the bell connection seat 7 remains constant up to the beginning of said lead-in surface; beyond this point, said clearance progressively increases, thereby increasing the clearance between the braking band 3 and the bell 4 in the radial or circumferentialand radial direction. This construction detail means that the contact zone between the dragging lateral faces and the bell, during braking, is not located in the outer portion of the seat near the outer diameter of the bell, but is more internal. In this way, the stress distribution between the two components is optimised, avoiding that the braking load is concentrated in the outermost zone of the bell-side seat. Stress concentrated in the outer zone, in fact, causes greater propagation of plastic deformation to the detriment of the bell material, impairing the safety and performance of the braking disc due to excessive plastic deformation.

[0111] . In accordance with a non-essential embodiment, the distance Al between the axis of the bell through-hole 11 and the rotation axis X-X coincides with the distance Bl between the beginning of said lead-in surface 27 and the rotation axis X-X.

[0112] . In accordance with a non-essential embodiment, the depth Zl, measured in the axial direction A-A, of said bell connection seat 7 coincides with the thickness Z2, measured in the axial direction A-A, of said braking band arm 5.

[0113] . In accordance with a non-essential embodiment, load transfer is optimal when the seat depth Zl is equal to the thickness of the dragging arms of the braking band Z2, that is when Zl = Z2.

[0114] . In accordance with a non-essential embodiment, thanks to the recess of the braking band flush with the outer surface of the bell, the contact area between the lateral faces is maximized, reducing stress since the load is distributed over a larger area. Moreover, from an aesthetic point of view, it is preferable to make the seatdepth Z1 equal to the thickness Z2 in order to obtain a smooth plane avoiding steps between the two components.

[0115] . In accordance with a non-essential embodiment, said braking band arms 5 extend from said braking band 3 in the radial direction R-R or along a direction inclined with respect to said radial direction R-R and circumferential direction C-C.

[0116] . In accordance with a non-essential embodiment, said braking band arms 5 extend from said braking band 3 radially along a direction inclined in a plane containing a radial direction R-R and a circumferential direction C-C, wherein said inclined direction forms an acute angle with respect to a radial direction R-R in its orientation away from said rotation axis X-X.

[0117] . In accordance with a non-essential embodiment, said braking band 3 comprises a braking portion 30 suitable for cooperating with opposite brake pads to perform a braking action.

[0118] . Said braking band arms 5 extend from a radially inner edge 31 of said braking portion 30 of said braking band 3.

[0119] . In accordance with a non-essential embodiment, said braking band 3 comprises an axisymmetric body around said rotation axis X-X.

[0120] . The following are some embodiments of the invention, provided by way of example and not limitation.

[0121] . The invention consists of a brake disc 1 for bicycles comprising a braking band 3 and a bell 4 or connection element to a wheel hub, suitably coupled and fixed by means of connection elements or rivets 12.

[0122] . The bell 4 or connection element to a wheel hub, made for example of aluminium, provides a connection portion for connection with a wheel hub of the bicycle at a radially inner surface, and a plurality of bell connection seats 7 for coupling with the braking band 3 at a radially outer surface. Each of said plurality of bell connection seats 7 is sized to have a first dimension (width) XI, a second dimension ( length) Yl, and a third dimension (depth) Zl. In particular, the depth of each bell connection seat Zl is smaller than the depth or thickness of the bell or connection element 4 to a wheel hub. At each bell connection seat 7, a first bell through-hole 11 with a diameter Ø1 is made. The distance between the centre of each bell through-hole 11 and a first interface surface (lower in the figures) of the bell connection seat is DI.

[0123] . The braking band 3, made for example of steel, has a ring shape bounded by an inner circumferential surface and an outer circumferential surface. At the inner circumferential surface, the braking band 3 includes a plurality of braking band arms 5 for its connection with the bell 4 or connection element to a wheel hub. In particular, each of said plurality of braking band arms 5 is sized to have a first dimension (width) X2, a second dimension (length) Y2, and a third dimension (depth) Z2. At each of said plurality of braking band arms 5, a second through-hole of the braking band arm 6 with a diameter Ø2 is made. The distance between the centre of each through-hole of the braking band arm 6 and a second interface surface (lower in the figures ) of the braking band arm is D2. Said plurality of braking band arms 5 is sized to allow the connection ofthe braking band 3 with the bell 4 or connection element to a wheel hub. More specifically, each of said plurality of braking band arms 5 is shaped to overlap in form-fitting coupling with one of said plurality of bell connection seats 7, so as to match the position of said first bell through-hole 11 with said second through-hole of the braking band arm 6.

[0124] . A connection element 12, for example a rivet, is inserted into said first bell through-hole 11 and said second through-hole of the braking band arm 6 to ensure the connection between the braking band 3 and the bell 4 or connection element to a wheel hub of the brake disc. The connection element 12 or rivet comprises a cylindrical portion, or shank 17, to be inserted into said first bell through-hole 11 and second through-hole of the braking band arm 6, said cylindrical portion being characterised by a diameter Ø3.

[0125] . The sizing of the bell connection seats 7 and the braking band arms 5 is also optimised to ensure the flotation of the brake disc 1 in the radial and tangential or circumferential directions. More specifically:

[0126] . • XI > X2 (thus clearance between the lateral faces of the bell connection seats 7 and the braking band arms 5) ensures tangential or circumferential flotation;

[0127] . • DI > D2 (thus clearance between the lower faces of the bell connection seats 7 and the braking band arms 5) ensures radial flotation;

[0128] . Furthermore:

[0129] . • Ø1 > Ø3 > Ø2 guarantees easy assembly and guarantees proper clearance in case of thermal stress on the materials.

[0130] . In accordance with one embodiment, the clearance between the connection element 12 or rivet and the respective seats or through-holes 6, 11 is greater than the clearance between the bell connection seats 7 and the braking band arms 5, in order to ensure radial and tangential flotation and to isolate the connection element 12 or rivet from the load transfer.

[0131] . Indeed, one of the aims of the invention is to ensure that the load is transferred directly from the braking band 3 to the bell 4 or connection element to a wheel hub, at the lateral faces of the bell connection seats 7 and the braking band arms 5.

[0132] . More specifically, each bell connection seat 7 is sized such that, for one of the two lateral faces, or seat walls 8, 9, the width XI is not constant throughout the length Yl, but increases over a length Y > DI. In this way, the load transfer between the braking band 3 and the bell 4 or connection element to a wheel hub is localised on the lateral wall of the bell connection seat 7 at the central part of said lateral wall of the bell connection seat 7, so as to achieve a reduced plastic deformation of the bell 4 or connection element to a wheel hub during braking actions.

[0133] . To the embodiments described above, a person skilled in the art, in order to meet contingent and specific needs, may apply numerous modifications, adaptations, and substitutions of elements with others functionally equivalent, without however departing from the scope of the following claims.

[0134] . LIST OF TERMS

[0135] . Brake disc ( 1 ): A brake disc of a disc brake compris ing a braking band and a bell or connection element to a wheel hub.

[0136] . Disc brake ( 2 ): The type of brake to which the described brake disc belongs, also known as braking ring.

[0137] . Braking band ( 3 ): Part o f the brake disc suitable for rotating about a rotation axi s.

[0138] . Bell ( 4 ): Connection element of the brake disc to a wheel hub, also known as spider or hub carrier.

[0139] . Braking band arms ( 5 ): Arms that are part o f the braking band.

[0140] . Braking band arm through-holes ( 6 ): Holes located on the arms of the braking band.

[0141] . Bell connection seats ( 7 ): Seats provided on the bel l for connection with the braking band arms.

[0142] . Seat wal ls ( 8, 9 ): Opposed walls delimiting the bell connection seat.

[0143] . Seat bottom wall ( 10 ): Wall delimiting the bell connection seat in the axial direction.

[0144] . Bell through-holes ( 11 ): Holes located in the bell connection seats.

[0145] . Connection element ( 12 ): Element, such as a rivet, connecting the braking band to the bell.

[0146] . Clearance or void ( 13 ): Space present between the connection element and the through-holes.

[0147] . Arm support walls ( 14, 15 ): Wal ls of the braking band armswhich counteract circumferential movements.

[0148] . Connection element head ( 16): Part of the connection element comprising a cross-dimension greater than the through-holes.

[0149] . Connection element shank ( 17 ): Cylindrical part of the connection element that fits into the through-holes.

[0150] . Enlarged riveting portion ( 18 ): Part of the connection element that is enlarged after assembly to secure the connection.

[0151] . Head cross-dimension ( 19): The cross-dimension of the head of the connection element.

[0152] . Riveting cross-dimension ( 20 ): The cross-dimension of the enlarged portion of the connection element after riveting.

[0153] . Elastic element (21 ): Element, such as a spring, interposed between the connection element and the bell or braking band.

[0154] . Shank abutment surface (22 ): Surface against which the braking band abuts.

[0155] . Receiving seats for the enlarged riveting portion (23 ): Seats around the through-holes housing the enlarged riveting portion of the connection element.

[0156] . Connection element discharge channel (24 ): Channel in the head of the connection element to ensure proper abutment.

[0157] . Inner radial arm plane ( 25): Plane of the braking band arms facing a seat radial plane.

[0158] . Seat radial plane (26): Plane connecting to the seat walls and facilitating the manufacturing process.

[0159] . Lead-in surface (27 ): Surface of the bell connection seatsthat facilitates alignment and insertion o f the braking band arms.

[0160] . Lead-in surface segment ( 28 ): Part of the lead-in surface, flat and inclined.

[0161] . Connection segment ( 29 ): Part o f the lead-in surface connected to the seat walls.

[0162] . Braking portion ( 30 ): Portion of the braking band cooperating with the brake pads.

[0163] . Radially inner edge ( 31 ): Edge of the braking portion from which the braking band arms extend.

[0164] . Discharge channel ( 32 ): Channel in the seat walls ensuring proper abutment of the braking band arms.

[0165] . Width of the bell connection seat (XI ): Cross-dimens ion of the bell connection seats.

[0166] . Width of the braking band arm (X2 ): Cross-dimension of the braking band arms.

[0167] . Length o f the bell connection seat (Yl ): Longitudinal dimension of the bell connection seats.

[0168] . Length o f the braking band arm (Y2 ): Longitudinal dimension of the braking band arms.

[0169] . Depth of the bell connection seat ( Zl ): Axial dimens ion of the bell connection seats.

[0170] . Depth of the braking band arm ( Z2 ): Axial dimension of the braking band arms.

[0171] . Diameter of the bell through-hole (01 ): Diameter of the through-holes in the bell.

[0172] . Diameter of the braking band arm through-hole (02 ):Diameter of the through-holes in the braking band arms.

[0173] . Diameter of the connection element (03): Diameter of the cylindrical part of the connection element.

[0174] . Distance between the centre of the bell through-hole and the interface surface of the bell connection seat (DI ): Specific radial distance for the bell hole.

[0175] . Distance between the centre of the braking band arm through-hole and the interface surface of the braking band arm (D2 ): Specific radial distance for the arm hole.

[0176] . Inclination of the lead-in surface (Beta): Angle of inclination of the lead-in surface with respect to the radial direction or to the extension direction of the connection seat.

[0177] . Inclination between the parallel segments of the arm support walls (Alfal ): Acute angle with respect to the radial direction, in an orientation away from the rotation axis.

[0178] . Inclination between the parallel segments of the seat walls (Alfa2 ): Acute angle with respect to the radial direction, in an orientation away from the rotation axis.

[0179] . Distance between the axis of the bell through-hole and the rotation axis (Al ): Specified radial distance for the bell hole.

[0180] . Depth evaluated in the axial direction of the bell connection seat (Zl ): Axial depth of the bell connection seat.

[0181] . Thickness evaluated in the axial direction of the braking band arm ( Z2 ): Axial thickness of the braking band arm.

[0182] . The present invention also relates to a disc brake comprising a brake disc 1 having a braking band 3 and a brakecalliper 33 fixed, i. e. non-rotating, to the vehicle and straddling the braking band 3 to apply with its pads a braking action to the brake disc 1.REFERENCE LIST1. brake disc2. disc brake3. braking band4. bell or connection element to a wheel hub5. braking band arms6. through-holes of braking band arms7. bell connection seats8. seat wall9. seat wall10. bottom wall of seat11. bell through-holes12. connection element or rivet13. clearance or gap between rivet and through-hole walls 14. arm support wall15. arm support wall16. head of connection element17. shank of connection element18. enlarged portion for riveting19. cross-dimension of head20. cross-dimension of riveting portion21. elastic element, e. g., cup spring22. abutment surface of shank23. receiving seats for enlarged portion for riveting 24. discharge channel of connection element25. inner radial plane of arm26. radial plane of seat27. lead-in surface28. segment of lead-in surface29. connection segment30. braking portion of the braking band31. radially inner edge32. seat discharge channel33. brake caliper

Claims

CLAIMS1. A brake disc ( 1 ) of di sc brake ( 2 ) comprising:a braking band ( 3 );said braking band ( 3 ) having a band body suitable for rotating about a rotation axis (X-X ) def ining axial directions (A-A) coincident with or parallel to said rotation axis (X-X), radial directions (R-R) orthogonal to said rotation axis (X-X ), and circumferential directions ( C-C ) each orthogonal to one of said axial directions (A-A) and one o f said radial directions (R-R) in an intersection point thereof;a bell ( 4 ), or connection element for the connection with a wheel hub;said braking band ( 3 ) comprises braking band arms ( 5 );said braking band arms ( 5 ) comprise braking band arm through-holes ( 6 );said bell ( 4 ) comprises bell connection seats ( 7 );said bell connection seats ( 7 ) comprise bell through-holes ( 11 ); wherein said band arm through-holes ( 6 ) face said bell through-holes ( 11 ) along an axial direction (A-A);a connection element ( 12 ) is inserted into each pair of mutually facing band arm through-hole ( 6 ) and bell through-hole ( 11 );said connection element ( 12 ) forms, when the brake disc ( 1 ) is not in a braking condition, a clearance or void ( 13 ) with said band arm through-hole ( 6 ) and said bel l through-hole ( 11 );said connection element ( 12 ) delimits the relative displacement between said braking band ( 3 ) and said bel l ( 4 ).

2. A brake disc ( 1 ) according to claim 1, whereinsaid braking band arms ( 5 ) extend in a plane containing a radial direction (R-R) and a circumferential direction ( C-C ) towards said rotation axi s (X-X ).

3. A brake disc ( 1 ) according to claim 1 or 2, whereinsaid braking band arms ( 5 ) comprise opposite arm support walls ( 14, 15 ), which form support surfaces at least in the circumferential direction (C-C ).

4. A brake disc ( 1 ) according to claim 3, whereinsaid opposite arm support walls ( 14, 15 ) comprise at least mutually parallel segments;or whereinsaid opposite arm support walls ( 14, 15 ) comprise at least mutually parallel segments which open an acute angle (Al fal ) with respect to a radial direction (R-R) and with orientation away from said rotation axi s (X-X ).

5. A brake disc ( 1 ) according to any one of the preceding claims, whereineach of said bell connection seats ( 7 ) is delimited by opposed seat wall s ( 8, 9 ), which delimit said bell connection seat ( 7 ) at least in the circumferential direction ( C-C ), and by a seat bottom wall( 10 ), which delimits said bel l connection seat ( 7 ) in the axial direction (A-A), so that said bell connection seat i 7 ) comprises a channel shape.

6. A brake disc ( 1 ) according to claim 5, whereinsaid opposed seat walls ( 8, 9 ) comprise at least mutually parallel se ments;or whereinsaid opposed seat walls ( 8, 9 ) comprise at least mutually parallel segments which open an acute angle (Al fa2 ) with respect to a radial direction (R-R) and with orientation away from said rotation axis (X-X ).

7. A brake disc ( 1 ) according to any one of the preceding claims whereinsaid braking band arms ( 5 ) are accommodated in said bel l connection seats ( 7 );or whereinsaid braking band arms ( 5 ) are accommodated in said bel l connection seats ( 7 ) leaving a clearance therebetween in the circumferential (C-C ) and radial (R-R) directions when said brake disc ( 1 ) is not in a braking condition.

8. A brake disc ( 1 ) according to claim 5 or 6 when dependent on claim 3 or 4, whereinsaid braking band arms ( 5 ) are accommodated in said bel l connection seats ( 7 ); and whereineach of said opposite arm support wall s ( 14, 15 ) compri ses at least one portion directly facing at least one portion of said opposed seat walls ( 8, 9 ); and whereinwhen said brake disc ( 1 ) is not in a braking condition, a clearance is present in the circumferential (C-C) and radial (R-R) directions between each of said at least one portion o f each of said opposite arm support walls ( 14, 15 ) and the facing each of said at least one portion of said opposed seat walls ( 8, 9 ).

9. A brake disc ( 1 ) according to any one of the preceding claims, whereinsaid connection element ( 12 ) compri ses a connection element head ( 16 ), a connection element shank ( 17 ), an enlarged riveting portion ( 18 );and whereinsaid connection element head ( 16 ) compri ses a head cross-dimension ( 19 ) greater than the cross-dimension of said bel l through-holes ( 11 ) and / or said band arm through-holes ( 6 ) and is suitable for counteracting relative axial displacements between bell ( 4 ) and braking band ( 3 );and whereinafter coupling, hence after riveting, said enlarged riveting portion ( 18 ) comprises a riveting cross-dimension ( 20 ) greater than thecros s-dimens ion of said band arm through-holes ( 6 ) and / or said bell through-holes ( 11 ) and is suitable for counteracting relative axial displacements between braking band ( 3 ) and bell ( 4 );and whereinafter coupling, hence after riveting, the axial extension of said connection element shank ( 17 ) is greater than the thickness dimension of said braking band ( 3 ) placed by the side of said bell ( 4 ), allowing a relative, controlled axial sliding of said braking band ( 3 ) with respect to said bell ( 4 ).

10. A brake di sc ( 1 ) according to any one o f the preceding claims, whereinafter coupling, the axial extens ion of said connection element ( 12 ) is greater than the thickness dimension of said braking band ( 3 ) placed by the side of said bell ( 4 ), allowing a relative, controlled axial sliding of said braking band ( 3 ) with respect to said bell ( 4 );and whereinan elastic element ( 21 ), which constantly biases said braking band ( 3 ) against said bell ( 4 ) either directly or through said connection element ( 12 ) is interposed between said connection element ( 12 ) and said bell ( 4 ) or said braking band ( 3 ).

11. A brake di sc ( 1 ) according to any one o f the preceding claims, whereineach braking band arm ( 5 ) compri ses an inner radial arm plane ( 25 ), which extends in a plane comprising an axial direction (A-A), said inner radial arm plane ( 25 ) i s flat in shape and faces a radial seat plane ( 26 ), which connects to seat wal ls ( 8, 9 ) and is also flat in shape, leaving a clearance between said inner radial arm plane ( 25 ) and said radial seat plane ( 2 6 ).

12. A brake di sc ( 1 ) according to any one o f the preceding claims, whereinsaid bell connection seat ( 7 ) comprises a lead-in surface ( 27 ); or whereinsaid bell connection seat ( 7 ) comprises a lead-in surface ( 27 ) which forms an enlargement of said bell connection seat ( 7 ) in the circumferential ( C-C ) and / or radial ( R-R) directions with respect to the remaining width of said bell connection seat ( 7 );and / or whereinsaid bell connection seat ( 7 ) comprises a lead-in surface ( 27 ) placed at the outer radial mouth of said bell connection seat ( 7 ); and / or whereinsaid bell connection seat ( 7 ) comprises a lead-in surface ( 27 ); said lead-in surface ( 27 ) compri ses at least one flat lead-in surface se ment ( 28 );or whereinsaid bell connection seat ( 7 ) comprises a lead-in surface ( 27 ); said lead-in surface ( 27 ) comprises at least a f lat lead-in surfacesegment ( 28 ) with predetermined inclination with respect to said radial direction ( R-R) or predetermined inclination (Beta ) with respect to the extens ion direction of the bell connection seat ( 7 ) or predetermined inclination (Beta ) with respect to the extension direction of the seat wall ( 8 ) of said bell connection seat ( 7 ) to which said lead-in surface ( 27 ) connects;or whereinsaid bell connection seat ( 7 ) comprises a lead-in surface ( 27 ); said lead-in surface ( 27 ) comprises at least a f lat lead-in surface segment ( 28 ) with predetermined inclination with respect to said radial direction ( R-R) or predetermined inclination (Beta ) with respect to the extens ion direction of the bell connection seat ( 7 ) or predetermined inclination (Beta ) with respect to the extension direction of the seat wall ( 8 ) of said bell connection seat ( 7 ) to which said lead-in surface ( 27 ) connects by means of a wide connection segment ( 29 ).

13. A brake disc ( 1 ) according to claim 12, whereinthe distance (Al ) between the axis of the bell through-hole ( 11 ) and the rotation axis (X-X ) coincides with the distance (Bl ) between the beginning of said lead-in surface ( 27 ) and the rotation axis (X-X ).

14. A brake di sc ( 1 ) according to any one o f the preceding claims, whereinthe depth ( Z l ), taken in the axial direction (A-A), of said bellconnection seat (7 ) coincides with the thickness ( Z2 ), taken in the axial direction (A-A), of said braking band arm (5 ).

15. A brake disc ( 1 ) according to any one of the preceding claims, whereinsaid braking band arms ( 5) extend from said braking band ( 3) in the radial direction (R-R) or along a direction inclined with respect to said radial (R-R) and circumferential (C-C) directions;or whereinsaid braking band arms (5 ) extend from said braking band (3) radially along an inclined direction in a plane containing a radial direction (R-R) and a circumferential direction (C-C), wherein said inclined direction forms an acute angle with respect to a radial direction (R-R) in the orientation thereof away from said rotation axis (X-X).

16. A brake disc ( 1 ) according to any one of the preceding claims, whereinsaid braking band ( 3) comprises a braking portion (30 ) suitable for cooperating with opposite brake pads to apply a braking action; and whereinsaid braking band arms (5) extend from a radially inner edge ( 31 ) of said braking portion ( 30) of said braking band ( 3).

17. A brake disc ( 1 ) according to any one of the preceding claimswhereinsaid braking band ( 3 ) comprises an axisymmetric body about said rotation axi s (X— X ).

18. A brake disc ( 1 ) according to claim 1, wherein the clearance ( 13 ) between the connection element ( 12 ) and the band arm through-holes ( 6 ) and the bell through-holes ( 11 ) is greater than the clearance between the braking band arms ( 5 ) and the respective bell connection seats ( 7 ), to ensure the radial and circumferential flotation of the braking band ( 3 ) with respect to the bell ( 4 ); and / or whereinthe band arm through-holes ( 6 ) are of a smaller size than the bell through-holes ( 11 );and / or whereinthe clearance ( 13 ) between the connection element ( 12 ) and each of the band arm through-holes ( 6 ) is less than the clearance ( 13 ) between the connection element ( 12 ) and each of the bell through-holes ( 11 ).

19. A brake disc ( 1 ) according to one of the preceding claims, wherein the dimensioning of the bell connection seats ( 7 ) and the braking band arms ( 5 ) is such that:- the width of the bell connection seat (XI ) is greater than the width of the braking band arm (X2 );- the distance between the center of the bell through-hole ( 11 ) andthe interface surface of the bell connection seat (DI ) is greater than the corresponding distance on the braking band arm (D2 );- the diameter of the bell through-hole (01 ) is greater than the diameter of the connection element (03), which in turn is greater than the diameter of the band arm through-hole (02 ), ensuring a correct clearance and flotation during thermal stresses.

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