FIELD OF THE INVENTION

The present invention relates to a braking band for a disc brake disc.

In particular, the present invention relates to a braking band of the ventilated type.

The present invention further relates to a disc of disc brake and to a disc brake.

BACKGROUND ART

In a disc brake, the brake caliper is generally arranged straddling the outer peripheral margin of a brake disc, adapted to rotate about a rotation axis defining an axial direction. In a disc brake, a radial direction (R-R), arranged substantially orthogonal to said axial direction (X-X), and a tangential or circumferential direction (C-C), orthogonal to both said axial direction (X-X) and said radial direction (R-R), is further defined. Known brake discs oppose two opposite braking surfaces facing the friction material of the opposite brake pads provided on the caliper body placed straddling the disc.

The brake pads, appropriately actuated, by closing against the opposite braking surfaces of the disc, apply a considerable friction adapted to create the desired braking torque which concurrently transforms the motion energy of the vehicle into heat, which accumulates in the body of the braking band of the disc brake and in the brake pads themselves. Indeed, this heat extends from the braking surfaces of the disc to the braking band and to the entire body of the brake disc, whereby heating, and sometimes overheating, the body of the caliper which is straddling the disc. In particular, in applications on high-performance vehicles and/or vehicles with high braking efficiency, the energies to be disposed of are extremely large.

Brake discs of ventilated type are generally known, i.e. discs comprising a braking band having two opposite and mutually facing plates on which opposite braking surfaces are made, adapted to cooperate with opposing brake pads of a brake caliper placed straddling the disc to apply the braking action.

As known, the discs of the type specified above consist of two coaxial parts or plates. A first part or plate is adapted to be connected to a supporting bell, which is intended to be connected in turn to a wheel hub of a vehicle. The remaining peripheral part of the disc, which comprises the two plates and is commonly referred to as a braking band, is intended to cooperate with calipers for disc brake adapted to apply a braking action on the vehicle, thus applying, by means of pads, friction on opposite surfaces of the two plates, named braking surfaces.

Usually, said two plates are distanced in axial direction whereby delimiting a hollow space and provide a plurality of axial connecting elements, such as fins or pins, which structurally connect said two plates to each other, thus forming a gap together with the two plates. Known ventilated disc solutions have recently and continuously evolved, in particular as regards the number and conformation of the so-called ventilation channels within said gap. Such ventilation channels are defined in turn inside by the presence of such connecting elements.

A need is strongly felt to cool the rotating disc brake quickly and effectively.

In particular, in order to maximize the heat extracted from the disc, it is important for the air current to flow inside the gap in turbulent conditions, while ensuring load losses which are as small as possible to maximize the flow rate of the overheated cooling flow, exiting from the radially outer edge of the braking band of the rotating disc brake.

It is known that excessively high brake disc temperatures decrease braking action efficiency and may cause the deformation of the braking band, the formation of cracks on braking surfaces and transformations of localized status of the material forming the braking band, which in turn causes its premature deterioration.

Such a need to increase the cooling efficiency must in all cases be mediated with the further need to keep the overall dimensions unchanged, particularly in the axial direction of the discs to avoid modifications of the vehicle suspension for which they are intended. The contrasting need to lighten the brake discs is also felt, because being unsprung masses, their weight is directly proportional to the inertia of the rotating disc during braking.

The geometry of the ventilation channels defined by the arrangement and shape of the connecting fins is of primary importance for the cooling performance of the braking band of the disc brake.

In a typical arrangement of the connecting fins between the plates of the braking band, they constitute modular units which are repeated mutually side-by-side in order to make cooling features as uniform as possible on the entire body of the disc.

For example, documents EP-2459896 and EP-2647864 to the same Applicant show modular units consisting of a radially inner range and a radially outer range of fins having tapered shape. The fins of the radially outer range, being circumferentially offset with respect to the fins of the radially inner range, define variable section ventilation channels and oppose axial baffles facing the centrifugal flow of the cooling current.

Such an arrangement of the fins implies that during rotation of the disc about its axis, the cooling air due to centrifugal motion impacts against the walls of the fins of the radially outer range, i.e. the fins which form said axial baffles, and is conveyed around them. The cooling air flow passing through narrow passages and bottlenecks, as well the enlargements, consisting of the connecting tabs, locally and alternatively accelerates and slows the flow rate escaping from the radially outer edge of the braking band, thereby promoting local turbulence and thus the cooling of the brake disc body.

Although advantageous from many points of view, these known solutions are not free from drawbacks. In particular, the load losses caused by the arrangement of the fins necessarily limit the flow rate, the cooling air flow speed and the heat transfer from the disc body to the cooling fluid itself.

The need is strongly felt to provide a braking band and disc brake solution, capable of ensuring improved cooling efficiency with the same dimension as known solutions.

The need is strongly felt to provide a braking band and disc brake solution, capable of providing increased cooling fluid flow rate, the disc rotation being the same.

The need is a strongly felt to provide a braking band and disc brake solution, capable of maximizing the heat exchange between the brake disc body and the cooling fluid current, without because of this having overall dimensions and weights incompatible with applications on high-performance vehicles.

Solution

It is an object of the present invention to solve the drawbacks of the prior art and to provide a solution to the needs described hereto with reference to the prior art.

It is an object of the present invention to suggest a solution of braking band for brake disc capable of maximizing cooling efficiency.

It is an object of the present invention to provide a solution of ventilated braking band of brake disc adapted to maximize the cooling fluid flow rate exiting from the disc and minimizing load losses despite ensuring turbulent flow conditions.

These and other objects are achieved by the braking band, the brake disc and the disc brake described in detail below.

Some advantageous embodiments are also described.

