Ventilated braking band, ventilated brake disc and method of ventilation

1. A ventilated braking band for a ventilated brake disc defining an axial direction, coinciding with the axis of rotation of the ventilated brake disc, a radial direction, orthogonal to the axial direction, and a tangential or circumferential direction, orthogonal to both the axial direction, and the radial direction:

said ventilated braking band comprises a first plate and a second plate, coaxial to the same axial direction;

said first plate and said second plate are mutually spaced apart in the axial direction so as to delimit a gap therebetween; wherein

said first plate comprises a first braking surface, adapted to face at least a first brake pad of a brake caliper which can be associated with said ventilated braking band; and wherein

said first plate comprises at least a first inner surface, facing said second plate, and wherein said first inner surface is substantially parallel to said first braking surface; and wherein

said second plate comprises a second braking surface, parallel and opposed to said first braking surface, so as to be adapted to face at least a second brake pad, opposite to said first brake pad of said brake caliper which can be associated with said ventilated braking band; and wherein

said second plate comprises a second inner surface, facing said first plate, and wherein said second inner surface is substantially parallel to said second braking surface; and wherein

said ventilated braking band comprises connecting elements extending in the axial direction between said first inner surface and said second inner surface, connecting together said first plate and said second plate; and wherein

said ventilated braking band comprises protrusions projecting from said first and second plates in said gap, without reaching the corresponding faced plate; and wherein

each of said protrusions connects together at least two separate connecting elements; and wherein

some of said protrusions, projecting in the gap from one of said first or second plate, form a protrusion group; and wherein

said protrusion group form a continuous or interrupted first protrusion group path, developing from the proximity of a radially inner edge to the proximity of a radially outer edge of said first and second plates; and wherein

said protrusion group projects from both plates forming at least said first and a second protrusion group path;

wherein the projections of said first and second protrusion group in a plane parallel to the first or second braking surface cross each other, creating a tortuous path for the ventilation of air.

2. The ventilated braking band, according to claim 1 , wherein

said connecting elements, said first inner surface and said second inner surface at least partially delimit ventilation channels inside said gap, and wherein

said ventilation channels are adapted to convey a fluid current flow for cooling said ventilated braking band; and wherein

a middle plane of said fluid current flow defines a gap middle plane; and wherein

said connecting elements have a substantially circular or oval or rhomboidal section in said gap middle plane forming connecting columns or pegs; and/or wherein

said connecting elements have a substantially elongated section in said gap middle plane according to a main extension direction forming fins; and/or wherein

said fins substantially extend along said first or second protrusion group path.

3. The ventilated braking band, according to claim 1 , wherein

said protrusion group, together with said connecting elements to which it is connected, forms a module repeating in said gap spaced apart in a circumferential direction; and/or wherein

said protrusion group, together with said connecting elements to which it is connected, forms a module repeating in said gap equally spaced apart in circumferential direction.

4. The ventilated braking band, according to claim 1 , wherein

said first or second protrusion group path extends in said gap along a curved line; or wherein

said first or second protrusion group path extends in said gap along a straight line; or wherein

said first or second protrusion group path extends in said gap along a straight line tilted with respect to a radial direction by a predetermined angle.

5. The ventilated braking band, according to claim 1 , wherein

said first or second protrusion group path extends in said gap in a continuous way thus avoiding interruptions or discontinuities separating the protrusions of the protrusion group from one another with a length of a first or second inner surface; or wherein

said first or second protrusion group path extends in said gap in a discontinuous way comprising interruptions or discontinuities separating at least some of the protrusions of the protrusion group with a length of a first or second inner surface.

6. The ventilated braking band, according to claim 1 , wherein

a connecting element has a connecting foot of the connecting element in a connecting portion to an inner surface of one of the first and second plates; said connecting foot enlarges an area which connects and puts into contact the connecting element with the inner surface; and/or wherein

said connecting foot of the connecting element is connected by a foot fitting with said connecting element and with said inner surface; and/or wherein

said connecting element has a rounded connecting element outer surface; and/or wherein

a protrusion has a protrusion connecting foot in a connecting portion to the inner surface of one of the first and second plates; said connecting foot enlarges an area which connects and puts into contact the protrusion with the inner surface; and/or wherein

said protrusion connecting foot is connected by a protrusion foot fitting to said inner surface; and/or wherein

said protrusion has a rounded protrusion outer surface.

7. The ventilated braking band, according to claim 1 , wherein

at least a protrusion group path connects with connecting elements being in a number ranging from three to eight; and/or wherein

at least a protrusion group path connects with five connecting elements; and/or wherein

at least one protrusion group path intersects separate protrusion group paths being in a number ranging from three to eight; and/or wherein

at least one protrusion group path intersects five separate protrusion group paths.

8. The ventilated braking band, according to claim 1 , wherein

at least one protrusion group path intersects at least one separate protrusion group path; and wherein

said protrusion group path extends in said gap in a continuous way thus avoiding interruptions or discontinuities separating the protrusions of the protrusion group from one another with a length of first or second inner surface; and wherein

said separate protrusion group path extends in said gap in a discontinuous way comprising interruptions or discontinuities separating at least some of the protrusions of the protrusion group with a length of first or second inner surface; and/or wherein

at least one protrusion group path intersects at least one separate protrusion group path; and wherein

said protrusion group path extends in said gap along a straight path; or wherein

said separate protrusion group path extends in said gap along a curved path.

9. The ventilated braking band, according to claim 1 , wherein

said first plate is connected with said second plate by at least a connecting element arranged in the proximity of the radially inner edge of each plate, and wherein

said at least one connecting element connects with at least one protrusion which extends without connecting with an adjacent connecting element.

10. The ventilated brake disc comprising a ventilated braking band as defined in claim 1 , and a connecting bell for connecting the disc with a hub or a vehicle door.