The present invention relates to brake discs to be used for disc brake systems on vehicles, especially on motorbikes, but suitable as well for other vehicles like, by way of example and without any limiting intent, cars, bicycles, commercial vehicles, trucks, trains and aircrafts.

State of the art

It is well known that brake discs efficency can be reduced, even drastically, because of overheating effect deriving from the contact and friction between the rotor and the brake pads insides brake callipers. Two main consequences are commonly noticed:

(a) The overheating of the disc rotor above the correct operating temperature, affects the friction effect with the brake pads and leads to undesired slippering effect, thus reducing the braking efficency and, in some extreme cases, getting the loss of the braking effect.

(b) The extreme overheating or continuous heating and cooling cycles of the disc rotor can negatively affect the rotor structure, leading to alterations, loss of hardness obtained with hardening process and finally producing deformations of the rotor and/or of the whole disc. This usually produces vibrations during braking phase on the front wheels (specially on motorcycles), loss of braking efficency and in some extreme situations to physical damages and sudden failure of the brake disc even causing some accidents.

Some solutions have been introduced for improving brake discs efficency and physical resistance against such problems. A first solution is that of increasing the thickness of the brake disc and/or rotor. Mass increase lead to higher heat absorption and relative dissipation properties, thus giving to the brake disc higher resistance and longer service life related to its use. On the other hand, some undesirable effects derive from higher mass and weight of the brake disc: (a) higher inertia during acceleration and braking actions all over the entire driving; and (b) higher gyroscopic effect, reducing driving agility (specially for motorcycles).

A second solution is the floating disc system. Such systems allow in some way to produce controlled deformations because of clearance present between the so called “carrier” (inner part) and the so called“rotor” (outer part), so allowing the material to deform and expand in controlled directions and reducing the risk of mechanical failure due to a more rigid system, like in an alternative fixed disc, where the whole disc is made in one piece. Moreover, floating disc systems partially reduce the overweight problem related to thickness increase because floating disc systems are made of different parts where only the outer part (the rotor) is built with the same material as a fixed disc (so, same mass increase per same diameter) while the inner part (the carrier) is made with lighter alloys (for example aluminium alloy). In any case, the weight and mass increase is obviously not solved for the rotor itself.

Another solution would be the use of different alloys and materials for producing discs and rotors. At present AISI410 and AISI420 are the most used materials. Other materials have been introduced, like carbon and carbo-ceramics for reducing the disc and/or rotor weight and mass, but this solution leads to a remarkable increase in the cost of the system (normal callipers and most of commercial sintered and mineral pads cannot be used with such discs and rotors). Moreover, it is to be noted a remarkable pollution due to production of potentially toxic fine carbon powders. Furthermore, specifically, carbo- ceramic discs and especially carbon discs showed some problems in wet conditions (water lubricating effect) and only some specific brands (like Brembo®) recently developed carbon brake disc systems which properly operate also in wet conditions. Summarizing, brake discs and brake systems comprising or made of carbon cannot be considered as a general and economically sustainable solution to be implemented in the market, but only for very specific applications like high level competitions (MotoGP® and Formulal®).

A further solution is the use of cooling holes in the rotor and disc. Initially made for renewing brake pads and for discharging the powdery material produced during such renewal process, they also help for heat dissipation, since they increase the disc and rotor surface exposed to air. Several brands, being inspired by the operation of radiators, provide lots of differently shaped hole for increasing the heat exchange capacity of the discs, thus reducing disc overheating risk.

Patent IT1276905A introduced the development of a special innovative hole, showing not only a better cooling efficency but also a certain weight reduction of brake discs for motorbike use, thanks to a specific geometry of the hole.

Patents FR2678694 and FR2700373 disclose the use of a double disc brake system wherein between the couple of discs, fixed the one to the other by means of V-shaped joints, an air chamber is created. Such system, even if it improves the cooling efficency of the system, still shows overweight problems and a certain structural weakness due to the V-shaped joints. It shows also a weight increase problem.

Moreover, with respect to rotor shape, in order to improve the cooling of the discs, several brands introduced some innovative shapes, different from the typical circular shape (for example: Wave discs, patent application EP995001 10.4).

Despite all the above listed solutions, no solution (carbon systems apart) could evidently overcome all the overheating problems deriving from friction between the rotor and the brake pads; thus the need still exists in the market of producing brake discs and rotors having a minimum reference thickness, usually well-known, for getting the minimum technical working structural resistance and braking effectiveness (obviously depending on use and applications). In the present state of the art, such restrictions about the thickness, associated with well-known materials (all but carbon) usually used for producing discs and rotors, lead to the fact that the typical weight related to discs available on the market, obviously depends on the external diameter of the disc and on other parameters related to application and to vehicle type on which the disc will be mounted.

In the specific case of front floating brake discs for motorbike use, it’s well known that brake discs or rotors are generally made of hardened AISI420, with a thickness comprised between 4,5mm and 5,0mm for obtaining a suitable mechanical strength and an effective braking action; the thickness can be lowered to 4,0mm for low quality discs within very acceptable limits and can be increased up to 5,5mm or 6,0mm for competition (either professional or amateur use).

The following table reports well known weight data related to front floating brake rotor discs for motorbike use (different kinds of professional use, and thus different disc diameters, all of them having a thickness of 6,0mm). The improvement introduced by IT1276905 is evident with respect to the percentage weight reduction.

Summarizing, based on the state of the art and related to the background, it can be stated that only recently, thanks to IT1276905 (and apart from the carbon disc systems), it became possible to reduce the weight of the rotors used in the main professional applications between 5% and 20% by weight, being still a technical problem a weight reduction higher that 20% because of thickening related issue. Finally, none of the existing disc brake systems shows a brake disc or rotor acting only as a contact element for producing friction with brake pads; conversely, in any case they all act as mechanical connectors as well, and they are structurally part of the connection itself with the carrier (through the nuts in the case of floating discs) or directly provide the connection with the vehicle (fixed disc case). It is known that none of the prior art brake systems (carbon and carbo-ceramics being included) permits a substantial reduction of operating temperatures of the system as a whole, which causes an overheating not only of the disc but also of the hydraulic system, leading to the known effect of brake fading. In facts it is known that, especially in the competitions, on the vehicles a system is mounted which allows the rider/driver to adjust pressure in the hydraulic system for compensating the losses due to the temperature increase. In extreme cases such compensations are not sufficient and a reduction in brake effectiveness of the system is obtained anyway, forcing the rider/driver to reduce speed and/or to increase accident risk.

Description of the invention

A first object of the present invention is to provide a new concept, design, building and assembly of all the parts needed for obtaining a brake disc compatible with most of the commercial disc brake systems, where the part or parts of the disc (identified in the present invention as“contact element” or“contact elements”) in direct contact with the brake pads inside the brake callipers, is an element which is totally independent, both from a structural and functional point of view, from the rest of the element, or elements (identified in the present invention as“support element” or“support elements”) needed for supporting and carrying the contact element, or elements, itself and for connecting the whole disc to the vehicle. This object is achieved through the features of the system of claim 1. Other embodiments of the invention are disclosed in the dependent claims. Another object of the present invention is to provide ranges of materials and geometries suitable for the contact elements broader than those typically used for known contact elements (properly“the rotor” in common floating discs and the disc itself in common fixed discs).

Another object of the present invention is to provide ranges of materials and geometries suitable for the support elements broader than those typically used for known support elements (properly“the carrier” in common floating discs and not existing in common fixed discs).

Another object of the present invention, is to provide a new brake disc compatible also with the more specific carbon disc brake systems.

Another object of the invention is to provide a weight reduction in the brake discs as follows: up to -20% w/w, preferably between -30% w/w and -50% w/w, in some cases up to -75% w/w with respect to most of the equivalent brake discs or rotors known in the state of the art.

Another object of the invention is to provide a reduction in the operating temperatures of the brake system. Due to its possibility of operating as an open system, to the remarkable increase of the specific surface of the contact elements which is exposed to air and to the possibility of providing them with multiple shapes and sizes (further to additional elements), thermal exchange is decidedly improved both in quantity and in kinetik terms, thus leading to reductions up to 50-60% in the peak temperature and in the normal operating temperature with respect to most of the equivalent brake discs or rotors of the prior art.

Throughout the description and claims, the word "comprise" and its variations do not involve the exclusion of other technical specifications, additions, components or steps. For those skilled in the art, other objects, advantages and features of the invention will be clear, partly from the description and partly from the use of the invention. The following examples and drawings are provided for illustrative purposes only and they are not intended to restrict this invention in any way. Moreover, this invention covers all possible combinations among the particular and preferred embodiments indicated here.

Brief description of the drawings

A very brief description of a series of drawings follows, which will help to better understand the invention and which expressly relate to embodiments of this invention which are presented as non-limiting examples of this invention.

FIG.1 shows a support element of the floating type according to the invention.

FIG.1a shows support elements of the combined type on which contact elements can be placed and locked.

FIG.2a shows a support element of the fixed type.

FIG.2b shows another embodiment of a support element of the fixed type.

FIG.2c shows a support element of the combined floating type.

FIG.2d shows a support element of the combined floating type - inner part or secondary support.

FIG.2e shows a support element of the combined floating type - seeger ring.

FIG.3a shows a contact element of the cylindric type with covered central body.

FIG.3b shows cover examples for central body of contact elements having shapes other than cylindric.

FIG.3c shows cover examples for central body of contact elements with grooves for dissipation of thermal energy.

FIG.4a shows a contact element of the cylindric type.

FIG.4b shows a contact element of the cylindric type, second embodiment.

FIG.4c shows a contact element of the cylindric type mounted on a floating support element.

FIG.4d shows a contact element of the cylindric type mounted on a fixed support.

FIG.4e shows a contact element of the cylindric type with a round shaped inner cover. FIG.5a shows contact elements - example 1. FIG.5b shows contact elements - example 2.

FIG.5c shows contact elements - example 3.

FIG.5d shows contact elements - example 4.

FIG.5e shows contact elements - example 5.

FIG.6 schematically shows contact elements of different sizes mounted on the same support element.

FIG. 7 schematically shows an axial view of a brake system according to the invention. FIGS 8. a to 8.f schematically show cross section views of a contact element mounted on a support element, according to various embodiments of the invention, in a cross section similar to the one operated along line VIII-VIII of figure 4d.

FIG. 9 shows an axonometric view of a brake disc of the combined type according to an embodiment of the invention.

FIG. 10 shows an axonometric view of a brake disc of the combined type according to an embodiment of the invention.

FIG. 11 shows an axial partly transparent view of a detail of a brake disc according to an embodimentof the invention, similar to the detail of figure 4.e.

FIG. 12 shows the detail of figure 11 wherein for clarity all components have been removed with the exception of a radiant element.

FIG. 13 shows the detail of figure 1 1 wherein for clarity all components have been removed with the exception of a cover.

FIG. 14 shows an axial view of a support element of the floating type according to the invention.

FIG. 15 shows an axial view of a support element of the perimeter type according to the invention

Detailed embodiment of the invention and examples

The invention relates to a brake system 40 for vehicles. The brake system 40 comprises a brake disc 42 rotatable around an axis and at least one brake calliper 44 comprising brake pads 46.

The brake system 40 according to the invention is characterized in that the brake disc 42 comprises a support element 48 and a plurality of contact elements 50 structurally independent from the support element 48, wherein:

the support element 48 comprises seats 52 housing the contact elements 50; the contact elements 50 comprise two plates 54 and a central body 56;

the two plates 54 are oversized with respect to the central body 56; and the two plates 54 provide friction surfaces 58 suitable for cooperationg with the brake pads 46 of the brake calliper 44. In the following description, the words“axial”,“radial” and“circunferential” are defined with respect to the rotation axis of the brake disc 42, assuming that all the components of the brake system 40 are properly mounted for carrying out their functions as designed. In the embodiments shown in the attached figures, the support element 48 has a circular outer profile. However this does not exclude that it could assume other shapes suitable for a brake disc 42, like for example a wavy or petal outer profile or any other outer profile which can meet specific use needs.

According to some embodiments (see for example fig. 15), the support element 48 is of the perimeter type. Such type of support element 48 holds the contact elements 50 on a radially inner band and extends radially toward outside (away from axis X) where it is configured for being connected in a fixed or floating manner to a rotating component of the vehicle, typically a wheel. Brake discs 42 of the perimeter type are known per se, but they have a quite limited use because of the heat which is transferred from the brake disc 42 firstly to the the wheel rim and then to the tyre. The brake discs 42 of the perimeter type according to the invention represent at least a partial solution for this specific problem; see in this respect the remarks which are reported below about the operating and peak temperatures of the brake disc 42 according to the invention.

In the specific embodiment of figure 15, the support element 48 of the perimeter type comprises seats 52 having radially outer entries 70. Such technical feature is not strictly necessary for the support elements 48 of the perimeter type, which in other embodiments can also have seats 52 with radially inner entries 70.

According to some embodiments, the support element 48 is of the monolithic type. Such type of support element 48 is made in one piece. It holds the contact elements 50 on its radial periphery and extends radially toward inside (toward axis X) where it is configured for being fixed directly to a rotating component of the vehicle in a rigid manner. In other words, the support element 48 of the monolithic type is fixed to the vehicle like a monolithic brake disc of a known type. Examples of support elements 48 of the monolithic type are provided in figures 4.d and 6. For simplicity, in figures 6 and 7 seats 52 have not been represented.

According to other embodiments, the support element 48 is of the combined type. Such type of support element 48 comprises in turn a secondary support 60. The support element 48 holds the contact elements 50 on its radial periphery, and it is connected to the vehicle by means of the secondary support 60 which is placed in a radially inner position (toward axis ). The secondary support 60 is fixed in a rigid manner on a rotating component of the vehicle, while the support element 48 can be connected to the secondary support 60 either in a rigid or in a floating manner, according to the specific needs. In other words, the support element 48 of the combined type is connected to the vehicle like a floating brake disc of the known type. Examples of support elements 48 of the combined type are provided in figures 1 , 2.c - 2.e, 9 and 10.

The support element 48 can be mounted on the secondary support 60 in different manners, known per se. For example the assembly can be obtained by means of one or more locking elements 62. An example of locking element 62 (seeger ring) is provided in figure 2.e.

The support element 48 comprises seats 52 (or free spaces 52) which house the contact elements 50. The seats 52 have preferably the form of slots. The seats 52 are through slots in the axial direction (they cross the entire axial thickness of the support element 48) and are closed in the radial and/or circumferential directions (so as to assure the structural continuity of the support element 48). According to some embodiments, the seats 52 have an entry 70 radially inner with respect to the support element 48 and develop in the radial direction and/or in the circumferential direction. According to other embodiments (see for example fig. 15), the seats 52 have an entry 70 radially outer with respect to the support element 48 and develop in the radial direction and/or in the circumferential direction.

According to some embodiments, each seat 52 is suitable for housing a plurality of contact elements 50.

According to some embodiments (see for example figures 1 , 4c, 6 14 and 15) the seats 52 are configured for housing the contact elements 50 arranged in a plurality of circumferential rows, wherein the circumferential rows develop at different radial postions the one from the other.

As already reported above, each contact element 50 comprises two plates 54 and a central body 56, wherein the two plates 54 are oversized with respect to the central body 56. The two plates 54 are placed at the two axial ends of the contact element 50. Both the two plates 54, and the central body 56 can assume various shapes, some of which are shown with exemplifying purpose in figures 5.a - 5.e.

In each contact element 50, the plates 54 are oversized with respect to the central body 56 in the radial and/or circumferential directions. In other words, a characteristic dimension of the plates 54 in the radial and/or circumferential directions (for example a diameter, a diagonal or more in general a size) is greater than an analogous characteristic dimension of the central body 56 in the same radial and/or circumferential directions.

Advantageously, the seats 52 obtained in the support element 48 are large enough for housing the central body 56 of the contact elements 50, but they are not large enough for allowing the passage in the axial direction of the plates 54 of the contact elements 50. Each contact element 50 is thus inserted in the respective seat 52 and it is slid along it in the radial and/or circumferential direction, until it reaches its final position which it maintains during its service life. In figure 4d (left) the arrow indicate the insertion path which is followed by the contact element 50 for reaching its position. The dimensions of the plates 54 of the contact element 50 axially secure it to the support element 48.

It is to be noted that the above described structure allows to obtain a large overall friction surface 58 (given by the sum of the friction surfaces 58 of the plates 54 of all the contact elements 50 provided on the brake disc 42 and, at the same time, to ensure great mechanical characteristics of the support element 48 (whose seats 52 are sized for housing only the central bodies 56 of the contact elements 50).

Preferably, each seat 52 houses more than one contact element 50. In such case, between two contact elements 50 placed in adjacent positions along the same seat 52, a spacer 64 is preferably interposed (see for example figure 2c).

Preferably the relative dimensions of the support element 48, of the seats 52, of the spacers 64, if any, and of the contact elements 50 are such that they allow some clearance between the support element 48 and the contact elements 50, allowing to properly set air flows adapted for cooling the system. For example, in some embodiments the axial extension of the central body 56 of a contact element 50 is slightly longer than the axial thickness of the respective support element 48. In this manner a predetermined axial clearance is obtained between the contact element 50 and the support element 48. Also, in some embodiments the transversal dimensions of the central body 56 of a contact element 50 are slightly smaller than the dimensions of the respective seat 52 in the support element 48. In this manner a predetermined radial and/or circumferential clearance is obrtained between the contact element 50 and the support element 48.

In some embodiments, when a contact element 50 is properly housed in the respective seat 52, it is able to freely rotate about an own axis parallel to axis X.

Each one of the movement possibilities conveniently given to the contact elements 50, both clearances in the three directions (axial, radial, circumferential) and rotation, allows to avoid undesirable stress peaks and optimizes cooling of the brake system 40.

Moreover, the relative dimensions which allows the presence of clearances, also imply a very reduced contact between the contact element 50 and the support element 48. In turn, the reduced contact represent an obstacle for the heat transfer from the contact element 50 (which heats up for friction during the braking action) to the support element 48.

According to some embodiments, the central body 56 of the contact element 50 comprises a cover 66 intended to create a thermal barrier. The cover 66 encircles the central body 56, interposing itself between the central body 56 and the walls of the seat 52 obtained in the support element 48. The cover 66 is preferably made of an insulating and/or heat-resistant material. Moreover, in some embodiments, the cover 66 comprises grooves 68 which increase its surface exposed to air in order to improve heat dissipation. Exemples of single covers 66 are shown in figures 3.b and 3.c. Each one of such covers 66 is suitable for encircling the central body 56 of one contact element 50 only. Another type of cover 66 is shown in figures 11 and 13. Such type of cover 66 is multiple, since it is suitable for encircling at the same time the plurality of central bodies 56 of a plurality of contact elements 50. In the specific example of figures 11 and 13, the cover 66 is double since it is suitable for encircling at the same time the two central bodies 56 of two contact elements 50.

According to another embodiment of the invention, between the support element 48 and the plates 54 of the contact element 50 a radiant element 69 is interposed. The radiant element 69, represented in figures 8b, 1 1 and 12, can advantageously have a substantially planar development in the plane perpendicular to axis X. Preferably, the axial thickness of the radiant element 69 is defined in such a manner that an axial clearance is maintained between the contact element 50 and the support element 48. Preferably the radiant element 69 is contoured so as to maximise the radiating surface. The presence of the radiant element 69, as well as the presence of the cover 66, helps to limit transmission of heat from the contact element 50 to the support element 48. Moreover the large radiating surface of the radiant element 69 and the presence of air around it cause a quick removal and dispersion of heat, thus limiting temperature.

The axially outer surfaces of the two plates 54 are friction surfaces 58, suitable for cooperating with the brake pads 46 of the brake calliper 44 for obtaining the braking action. According to some embodiments, the plates 54 comprise a perimetral chamfer 72 or bevel. In this manner cooperation is made easier between the friction surfaces 58 of the contact elements 50 and the brake pads 46 of the brake calliper 44.

During their service life the contact elements 50 are preferably monolithic. Despite this, the fact remains that during the manufacturing steps thay can be assembled starting from separated elements, even made of different materials. However it is preferable that during the service life it is no more possible to separate the plates 54 from central body 56 without irreparably breaking the contact element 50.

It was surprisingly found that the design, building and assembly of a new concept of a support element 48 (as described in this invention) with a new concept of the contact elements 50 (as described in this invention) lead to the production of brake discs 42 compatible with most of the disc brake systems, and/or to a lower weight than brake discs 42 commonly known in the state of the art, as well as to a reduction of the known peak and operating temperatures. This invention comprises a brake disc 42 made up by an outer, preferably round piece, called support element 48, that should not to be confused with the commonly known “carrier” related to floating discs and being an inner part of the disc. The support element 48 is designed in such a way to provide specifically made free spaces 52 (or seats 52) intended for accommodating the so-called contact elements 50, specifically designed for housing the contact element 50 which acts as structurally and functionally independent contact and friction element with the brake pads 46 inside the braking callipers 44, thus creating the actual braking action.

In such system, the support element 48 is physically and structurally independent from the contact elements 50 which are specifically designed only for producing the friction and braking effect, being as a whole a construction and design concept independent from any other brake disc 42 known in the state of the art.

In an embodiment of the invention, the support element 48 can be designed with the same concept of the floating discs, thus being connected to the vehicle through secondary supports 60 (e.g. carrier and nuts). A non-limitative example is shown in FIG.1. In an alternative embodiment of the invention, the support element 48 can be designed with the same concept of the fixed discs, being directly connected to the vehicle, as can be shown in FIG.2a and FIG.2b.

In an alternative embodiment of the present invention, the support element 48 (called, in this case,“combined support element”) can be connected to the vehicle by means of a fixed secondary support 60 specially designed for specifically fitting with the first support element 48 and finally getting blocked and fixed through a third element called“locking element 62”. Non-limitative examples are reported in FIG. 2c, FIG. 2d and FIG. 2e.

In an embodiment, the free spaces 52 for accommodating and/or blocking the contact elements 50 are obtained through a single disc which acts as a support element 48 (non- limitative examples are reported in FIG. 1 and FIG. 4d). In an alternative embodiment of the present invention, the free spaces 52 for accommodating and/or blocking the contact elements 50 are obtained with the use of two support elements 48 specifically designed and directly connected to each other without any gap therebetween (as shown in FIG. 1 a).

In an alternative embodiment, the present invention provides a weight reduction for the brake discs 42 as follows: up to -20% w/w, preferably between -30% w/w to -50% w/w, in some cases up to -75% w/w with respect to most of the equivalent brake discs 42 or rotors at present known in the state of the art.

In an embodiment, the invention provides a reduction of the operating temperature of the brake discs 42 of up to 50-60% of the peak and normal operating temperature, with respect to most of the equivalent brake discs 42 or rotors at present known in the state of the art.

In an embodiment of the present invention, the outer disc called support element 48 can be produced with materials which are not necessarily submitted to a hardening process and/or having a thickness lower than the thickness typically known for the external rotors of the floating discs and lower than the thickness of fixed discs. In an alternative embodiment, the support element 48 has a thickness even lower than the thickness of the carriers commonly used in the floating discs.

In an embodiment of the present invention, the support element 48 is made of an aluminium alloy (AL 6082T6) and has a thickness comprised between 0,5 and 5,0mm, preferably between 1 ,5 and 3,5mm, more preferably between 2,0 and 2,5mm.

In an alternative embodiment of the present invention, the support element 48 can be made of aluminium AL6082T6 or of hardened steel alloy AISI410 or AISI420, having a thickness comprised between 0,5 and 5,0mm, preferably between 1 ,5 and 3,5mm, more preferably between 2,0 and 2,5mm.

In an alternative embodiment, non limiting examples of other materials are represented for any other steel alloy, iron and/or iron alloys, titanium and/or titanium alloys, aluminium and/or aluminium alloys, beryllium and/or beryllium alloys, magnesium and/or magnesium alloys, carbon and/or carbon fibres, cast-iron, plastic materials, ceramic materials, composite materials, which can be used for producing the support element 48 and/or the combined support elements, specifically designed for accommodating the contact elements 50. Appropriate thickness and materials have to be chosen and fine- tuned depending on specific vehicle application and disc performance requirements.

No upper limit for thickness is thought to exist for the support element 48; it depends on the disc brake system to be mounted on, the application and performance required, as well as on the contact elements 50 to be mounted and/or blocked therein.

In an embodiment of this invention, the contact elements 50 are made of hardened steel alloy AISI410 or AISI420; in an alternative embodiment, non limiting examples of other materials are represented for any other steel alloy, iron and/or iron alloys, titanium and/or titanium alloys, aluminium and/or aluminium alloys, beryllium and/or beryllium alloys, magnesium and/or magnesium alloys, carbon and/or carbon fibres, cast-iron, plastic materials, ceramic materials, composite materials, carbo-ceramic materials which can be used for producing the contact elements 50, depending on the disc brake system to be mounted on, the application and performance required and as well depending on the brake pads 46 contained in the brake callipers 44.

No upper limit for thickness is thought to exist for the contact elements 50, depending on the disc brake system to be mounted on, the application and performance required. In an embodiment of this invention, the contact elements 50 are obtained from one single piece of material by turning, milling, die-melting, CNC, laser cutting, water cutting, plasma cutting, but not only; in an alternative embodiment, the contact elements 50 are obtained by joining or connecting more than one single piece by mechanical joining, welding, die-casting, bonding, electric welding, braze-welding, vacuum welding, but not only.

In an embodiment of this invention, the contact elements 50 have a cylindrical shape with oversized diameter both on upper and lower plates, and are accommodated and/or blocked on a floating, fixed or fixed-combined support element 48. Here and below, the wording“upper” and“lower” refer to the relative positions assumed by the plates 54 of the contact elements 50 as represented in the attached figures. Non limiting examples are reported in FIGs. 4a, 4b, 4c, 4d and 4e; in an alternative embodiment, several other geometries can be used for producing the contact elements 50, independently from the corresponding designed support element 48. Non limiting examples for alternative geometries are shown in FIGs. 5a, 5b, 5c, 5d and 5e.

In an alternative embodiment, different contact elements 50 with different shapes and sizes can be accommodated on the same support element 48 at same time. A non limiting example is shown in FIG.6.

In an alternative embodiment, more than one row of contact elements 50, having the same or different shapes and made of the same or different materials, can be mounted on the same support element 48 at the same time. A non limiting example is shown in FIG. 14.

In an embodiment of the present invention, the inner and outer plates 54 of the contact element 50 have the same thickness and geometry. In an alternative embodiment, the inner and outer plates 54 of the contact element 50 have different thickness and/or geometry the one from the other and even with respect to the central body 56 of the contact element 50.

A main difference between what is known in the state of the art and the contact element 50 described in the present invention resides in that the latter does not need the same structural resistance as required by the parts in contact with the brake pads 46 for other well-known brake discs 42, being either fixed models (the whole disc itself) or floating models (the so-called rotor): (i) to a major extent, when comparing with fixed discs, where the part in contact with brake pads 46 is a whole single part with the disc itself, connected to the vehicle; and (ii) to a minor extent, when comparing with floating discs, where the part in contact with brake pads 46 still has a main function for connection with the inner part called“carrier” through the“nuts”. Therefore, a broader range of materials, thickness and geometries can be used for obtaining the contact parts as described in this invention. In an alternative embodiment of this invention, the contact elements 50 can be obtained combining different parts, made of same or of different materials.

In an embodiment, the central body 56 and/or inner plates 54 of the contact elements 50 in direct contact with the support element 48 can be covered with a cover 66 or with a layer specifically made of: (i) an insulating materials for reducing or avoiding heat transmission from the contact elements 50 to the support element 48; and/or (ii) reinforced materials for avoiding any early wear due to the direct contact between the central body 56 of the contact element 50 and the support element 48.

A non limiting example is reported for a cylindrical shape contact element 50 with central body 56 covered by a specific heat protection cover 66 (see FIG. 3a). Non limiting examples are reported for covering elements 66 of the central body 56 of contact elements 50 having a geometry different from cylindrical shape (see FIG.3b).

In an alternative embodiment of the present invention, the covering elements 66 of the central body 56 are provided with specific grooves 68 for heat dissipation. Non limiting examples are reported in FIGs. 3c and 4e.

As a general summary, it can be stated that such a high flexibility obtainable by combining the geometries, sizes and materials of the contact element 50 with the materials and thickness of the support element 48, for producing the brake disc 42 as presented in this invention, cannot be offered by none of the existing brake disc 42 type as per the state of the art.

Example 1. Brake disc made of:

An outer support element 48 (FIG. 2c), belonging to a combined support type element, to be combined with inner secondary support 60. It is made of aluminium alloy AL6082T6 (density 2,7 kg/dm ³ ), thickness 2mm, external diameter 320mm, internal diameter 250mm, obtained by laser cutting. The inner secondary support 60 (FIG. 2d) belongs to a combined support type element, to be combined with the outer support element 48. It is made of aluminium alloy AL6082T6 (density 2,7 kg/dm ³ ), thickness 2mm, external diameter 250mm, internal diameter and offset adaptable to any motorbike rim, CNC produced. It corresponds to what is commonly named“carrier” in the floating discs type, but it is specifically shaped for combining with the“support element 48” described above. The locking element 62 (FIG. 2e) is made of steel alloy AISI304 through a laser cutting manufacturing process, and is riveted so as to lock the support elements 48 and 60. The contact elements 50 (FIG. 4e) are made of hardened steel alloy AISI420 and are shaped like a cylindrical spinning wheel; the upper and lower plates 54 are oversized with respect to the central body 56. The dimensions are as follows:

Upper and lower plates 54: 30mm diameter and 2mm thickness. Central body 56: 13mm diameter and 2mm thickness.

Total height 6mm.

The central body 56 is covered with a cylindrical cover 66 made of hardened steel alloy AISI420, with internal diameter 13mm, external diameter 15mm, height 2mm and further provided with grooves 68 on the internal surface for heat dissipation. Thirty contact elements 50 are arranged and housed in the free spaces 52 provided by the support element 48, then combined with the secondary support 60 and finally everything is blocked by the locking element 62. Such composition provides a brake disc 42 compatible with several disc brake systems and equivalent to one having similar external diameter size (320mm) and thickness (6mm), made of hardened AISI420 steel alloy. The comparisons of weight and temperature are as follows:

Example 1 (external support element 48 only + contact elements 50): total weight 81 Og. Equivalent floating disc of other brands (external rotor only): from 1350g to 1676g. Weight reduction: from -40% w/w to -52% w/w

Example 1 (whole disc): total weight 11 1 Og. Equivalent floating disc of other brands: 1800g. Weight reduction: -38% w/w

Example 1 (whole disc): normal operating temperatures are reached of 200-300°C and peak temperatures not higher than 350-370°C, when standard operating temperatures are 400-500°C with peak temperatures of 600-650°C in extreme cases.

Example 2. Brake disc 42 made of:

A floating type support element 48 (FIG. 1), to be mounted on a 12 nuts secondary support 60. It is made of aluminium alloy AL6082T6 (density 2,7 kg/dm ³ ), thickness 2mm, external diameter 320mm, internal diameter 235mm, obtained by laser cutting. The contact elements 50 (FIGs 4a, 4b and 4c) are made of hardened steel alloy AISI420 and are shaped like a cylindrical spinning wheel; the upper and lower plates 54 are oversized with respect to the central body 56. The dimensions are as follows:

Upper and lower plates 54: 16mm diameter and 2mm thickness.

Central body 56: 8mm diameter and 2mm thickness.

Total height 6mm.

Ninety-six contact elements 50 are mounted and housed in the free spaces 52 provided by the support element 48. Such composition provides a brake disc 42 compatible with several disc brake systems and equivalent to a rotor having a similar external diameter with similar diameter size (320mm) and thickness (6mm), made of hardened AISI420 steel alloy. The comparisons of weigth and temperature are as follows:

Example 2 (external support element 48 + contact elements 50): total weight 816g. Equivalent floating disc of other brands (external rotor only): from 1350g to 1676g. Weight reduction: from -39% w/w to -51 % w/w Example 2 (whole disc): like example 1 , normal operating temperatures are reached of 200-300°C and peak temperatures not higher than 350-370°C, when standard operating temperatures are 400-500°C with peak temperatures of 600-650°C in extreme cases. Example 3. Brake disc 42 made of:

A floating type support element 48 (FIG 1), to be mounted on a twelve nuts secondary support 60 and made of steel alloy AISI 420 (density 7,9 kg/dm ³ ), thickness 2mm, external diameter 320mm, internal diameter 235mm, obtained by laser cutting. The contact elements 50 (FIGs 4a, 4b and 4c) are made of hardened steel alloy AISI420 and are shaped like a cylindrical spinning wheel; the upper and lower plates 54 are oversized with respect to the central body 56. The dimensions are as follows:

Upper and lower plates 54: 16mm diameter and 2mm thickness.

Central body 56: 8mm diameter and 2mm thickness.

Total height 6mm.

Ninety-six contact elements 50 are mounted and housed in the free spaces 52 provided by the support element 48. Such composition provides a brake disc 42 compatible with several disc brake systems and equivalent to a rotor having a similar external diameter with similar diameter size (320mm) and thickness (6mm), made of hardened AISI420 steel alloy. The weight comparisons are as follows:

Example 3 (external support element 48 + contact elements 50): total weight 1071g. Equivalent floating disc of other brands (external rotor only): from 1350g to 1676g. Weight reduction: from -21 % w/w to -36% w/w.

Example 4. Brake disc 42 made of:

A floating type support element 48 (FIG 1), to be mounted on a twelve nuts secondary support 60; it is made of aluminium alloy AL6082T6 (density 2,7 kg/dm ³ ), thickness 3mm, external diameter 320mm, internal diameter 235mm, obtained by laser cutting. The contact elements 50 (FIGs 4a, 4b and 4c) are made of hardened steel alloy AISI420 and are shaped like a cylindrical spinning wheel; the upper and lower plates 54 are oversized with respect to the central body 56. The dimensions are as follows:

Upper and lower plates 54: 16mm diameter and 1 ,5mm thickness.

Central body 56: 8mm diameter and 3mm thickness.

Total height 6mm.

Ninety-six contact elements 50 are mounted and housed in the free spaces 52 provided by the support element 48. Such composition provides a brake disc 42 compatible with several disc brake systems and equivalent to a rotor having a similar external diameter with similar diameter size (320mm) and thickness (6mm), made of hardened AISI420 steel alloy. The weight comparisons are as follows: Example 4 (external support element 48 + contact elements 50): total weight 829g. Equivalent floating disc of other brands (external rotor only): from 1350g to 1676g. Weight reduction: from -38% w/w to -51% w/w.

Example 5. Brake disc 42 made of:

A floating type support element 48 (FIG 1), to be mounted on a twelve nuts secondary support 60, made of steel alloy AISI 420 (density 7,9 kg/dm ³ ), thickness 3mm, external diameter 320mm, internal diameter 235mm, obtained by laser cutting. The contact elements 50 (FIGs 4a, 4b and 4c) are made of hardened steel alloy AISI420 and are shaped like a cylindrical spinning wheel; the upper and lower plates 54 are oversized with respect to the central body 56. The dimensions are as follows:

Upper and lower plates 54: 16mm diameter and 1 ,5mm thickness.

Central body 56: 8mm diameter and 3mm thickness.

Total height 6mm.

Ninety-six contact elements 50 are mounted and housed in the free spaces 52 provided by the support element 48. Such composition provides a brake disc 42 compatible with several disc brake systems and equivalent to a rotor having a similar external diameter with similar diameter size (320mm) and thickness (6mm), made of hardened AISI420 steel alloy. The weight comparisons are as follows:

Example 5 (external support element 48 + contact elements 50): total weight 1131 g. Equivalent floating disc of other brands (external rotor only): from 1350g to 1676g. Weight reduction: from -16% w/w to -33% w/w.

Example 6. Brake disc 42 made of:

A floating type support element 48 (FIG 1), to be mounted on a twelve nuts secondary support 60, made of titanium alloy Tl (density 4,6 kg/dm ³ ), thickness 2mm, external diameter 290mm, internal diameter 220mm, obtained by laser cutting. The contact elements 50 (FIGs 4a, 4b and 4c) are made of hardened steel alloy AISI420 and are shaped like a cylindrical spinning wheel; the upper and lower plates 54 are oversized with respect to the central body 56. The dimensions are as follows:

Upper and lower plates 54: 16mm diameter and 2mm thickness.

Central body 56: 8mm diameter and 2mm thickness.

Total height 6mm.

Ninety-six contact elements 50 are mounted and housed in the free spaces 52 provided by the support element 48. Such composition provides a brake disc 42 compatible with several disc brake systems and equivalent to a rotor having a similar external diameter with similar diameter size (290mm) and thickness (6mm), made of hardened AISI420 steel alloy. The weight comparisons are as follows: Example 6 (external support element 48 + contact elements 50): total weight 741 g. Equivalent floating disc of other brands (external rotor only): from 1180g to 1441g. Weight reduction: from -37% w/w to -49% w/w.

Example 7. Brake disc 42 made of:

A floating type support element 48 (FIG 1), to be mounted on a twelve nuts secondary support 60, made of titanium alloy Tl (density 4,6 kg/dm ³ ), thickness 2mm, external diameter 320mm, internal diameter 235mm, obtained by laser cutting. The contact elements 50 (FIGs 4a, 4b and 4c) are made of hardened steel alloy AISI420 and are shaped like a cylindrical spinning wheel; the upper and lower plates 54 are oversized with respect to the central body 56. The dimensions are as follows:

Upper and lower plates 54: 16mm diameter and 2mm thickness.

Central body 56: 8mm diameter and 2mm thickness.

Total height 6mm.

Ninety-six contact elements 50 are mounted and housed in the free spaces 52 provided by the support element 48. Such composition provides a brake disc 42 compatible with several disc brake systems and equivalent to a rotor having a similar external diameter with similar diameter size (320mm) and thickness (6mm), made of hardened AISI420 steel alloy. Weight comparisons are as follows:

Example 7 (external support element 48 + contact elements 50): total weight 908g. Equivalent floating disc of other brands (external rotor only): from 1350g to 1676g. Weight reduction: from -33% w/w to -46% w/w.

The description and the examples reported above particularly refer to brake discs 42 intended for motorcicle use. It is to be noted that the whole axial thickness s of the brake discs 42 of the examples reported above is always 6 mm. Such axial thickness s allows to use a brake disc 42 according to the invention in substitution of a brake disc 42 of the known type, without carrying out any further changes on the motorcicle.

In particular, figures 8. a and 8.b show like an example two embodiments of the brake disc 42 of the invention characterized by an axial thickness s for motorcicle use, for example of 5-6 mm.

Figure 8. a shows a simple and light solution, while figure 8.b shows a solution in which radiant elements 69 are interposed between the plates 54 of the contact element 50 and the support element 48.

However, the brake system 40 according to the invention can be used also for other vehicles such as, for example: cars, industrial or commercial vehicles, trains or aircrafts. As the skilled person can easily understand, it is possible to manufacture the brake disc 42 of the invention according to very different dimensions, suitable for making it compatible with different types of brake disc 42 of the prior art. In particular, figures 8.c - 8.f and 10 show like an example some embodiments of the brake disc 42 of the invention characterized by a higher axial thickness s. For example, it is known that in the automotive field brake discs 42 are used having axial thickness s of 18-30 mm.

Figures 8.c and 10 show solutions for providing a brake disc 42 having high axial thickness s according to the invention. In such embodiments the support element 48 is double and comprises two semi-support elements 48’ placed at a predetermined axial distance the one from the other. In such case the central body 56 of the contact elements 50 has an axial extension suitable for the distance between the two semi-support elements 48’.

Figures 8.d, 8.e and 8.f show other solutions for providing a brake disc 42 of high axial thickness s according to the invention. In such embodiments the support element 48 is single, and the contact element 50 has a predetermined axial extension. In the embodiments of the figures 8.d and 8.e, in order to maintain the contact element 50 firm on the support element 48 in the axial direction (with the exception of the axial clearance disclosed above), the central body 56 of the contact element 50 comprises a recess 74 suitable for being housed in the seat 52 obtained on the support element 48. In this manner the shoulders which delimit the recess 74 define axial abutments for the contact element 50 on the support element 48. In the solution of figure 8.d the recess 74 is obtained in an axially symmetrical position along the central body 56 of the contact element 50. On the contrary, in the solution of figure 8.e the recess 74 is obtained in an axially asymmetrical position along the central body 56 of the contact element 50. Conversely, in the solution of figure 8.f the plates 54 of the contact element 50 have an increased axial development in order to provide a longer service life.

According to some embodiments of the brake system 40 of the invention, the brake calliper 44 has a limited circumferential extension with respect to the whole friction surface of the brake disc 42. According to some embodiments, the brake calliper 44 surrounds an arc of the brake disc 42 smaller than 90°. Such embodiments are particularly appreciated for terrestrial vehicles such as motorcicles, cars, commercial vehicles and trains, where there is the need of quickly dissipating the heat deriving from the braking action in order to maintain the system ready.

According to other embodiments of the brake system 40 of the invention, the brake pads 46 have a circumferential extension substantially equal to the one of the whole friction surface 58 of the brake disc 42. According to such embodiments, the brake pads 46 cover almost completely the circumference of the brake disc 42. Such embodiments are particularly appreciated for aircrafts, where there is the need of exploiting as much as possible the friction surface 58 in order to maximise the effectiveness of the braking action with respect to the mass of the brake system 40.

Preferably the brake system 40 for vehicles according to the invention comprises brake pads 46 inside brake callipers 44 and a support element 48,

wherein the brake system 40 comprises an outer part 48 which comprises a plurality of free spaces 52 housing a plurality of contact elements 50;

wherein the contact elements 50 are so arranged to act as independent contact and friction elements with the brake pads 46 inside the brake callipers 44;

and wherein the support element 48 is physically and structurally independent from the contact elements 50.

Preferably the support element 48 is connected to the vehicle by means of a floating secondary support 60.

Preferably the support element 48 is directly connected to the vehicle.

Preferably the support element 48 is connected to the vehicle by means of a fixed secondary support 60, configured for accomodating the support element 48 and for being blocked and fixed by a locking element 62.

Preferably the free spaces 52 are obtained by means of a disc with a single support element 48.

Preferably the free spaces 52 are obtained by means of the use of two different support elements 48, which are directly connected the one to the other without any gap between them.

Preferably the support element 48 is made of at least one material selected among: alluminium and/or alluminium alloy, steel and/or steel alloy, iron and/or iron alloys, titanium and/or titanium alloys, berillium and/or berillium alloys, magnesium and/or magnesium alloys, carbon and/or carbon fibers, cast-iron, plastic materials, ceramic materials, carbo-ceramic materials and composite materials.

Preferably the thickness of the support element 48 is comprised between 0,5 mm and 5,0 mm, preferably between 1 ,5 mm and 3,5 mm, and more preferably between 2,0 mm and 2,5 mm.

Preferably an upper limit is not defined for the thickness of the support element 48. Preferably the contact element 50 is made of at least one material selected among: alluminium and/or alluminium alloy, steel and/or steel alloy, iron and/or iron alloys, titanium and/or titanium alloys, berillium and/or berillium alloys, magnesium and/or magnesium alloys, carbon and/or carbon fibers, cast-iron, plastic materials, ceramic materials, carbo-ceramic materials and composite materials.

Preferably the contact element 50 is provided with a cover 66 for obtaining thermal insulation and/or longer service life. It is clear that the specific features are described with respect to different embodiments of the invention with exemplifying and non limiting purpose. Obviously a skilled technician of the field will be able to carry out further changes and modifications to the present invention, in order to meet specific and special needs. For example the technical features described with reference to one embodiment of the invention can be extrapolated from it and applied to other embodiments of the invention. Such changes and modifications are in any case comprised within the scope of protection of the invention, which is defined by the following claims.