Ventilated wheel assembly

1. A wheel assembly which comprises a wheel ( 2 ) having an axis (X-X′) and a system ( 4 ) for braking the wheel ( 2 ), in which a fan ( 6 ) is arranged along the axis of the wheel ( 2 ) in order to cool the braking system ( 4 ), the fan ( 6 ) comprising a rotor ( 14 ) which rotates about the axis (X-X′) and which is provided with a plurality of peripheral blades ( 22 ), the rotor ( 14 ) being arranged in an air circulation channel ( 50 ) which is delimited by an internal annular wall ( 54 ) of the wheel ( 2 ) so that an operational clearance ( 56 ) is provided between the wall ( 54 ) and the radial ends of the rotor ( 14 ), wherein the rotor ( 14 ) of the fan ( 6 ) comprises a collar ( 24 ) which connects the outer radial ends of the blades ( 22 ) together, and wherein the operational clearance ( 56 ) is provided between the internal annular wall ( 54 ) of the air circulation channel ( 50 ) and the collar ( 24 ).

2. The wheel assembly according to claim 1 , wherein a shroud ( 8 ) is arranged against the rim ( 3 ) of the wheel ( 2 ), and carries at an end remote from the rim ( 3 ) a protection element ( 10 ), the channel ( 50 ) for circulating air from the rim ( 3 ) towards the outer side of the wheel ( 2 ) being formed by at least one internal wall ( 52 ) of the shroud ( 8 ) and an internal wall ( 54 ) of the protection element ( 10 ), the rotor ( 14 ) being arranged in the air circulation channel ( 50 ) so that the operational clearance ( 56 ) is provided between the internal wall ( 54 ) of the protection element and the collar ( 24 ).

3. The wheel assembly according to claim 2 , wherein the protection element ( 10 ) comprises a protection grid ( 26 ) which is formed by ribs ( 29 ) and which is positioned so as to face, along the axis (X-X′), the blades ( 22 ) of the rotor ( 14 ).

4. The wheel assembly according to claim 2 , wherein the shroud ( 8 ) is formed by an external shell ( 32 ) and a shroud support ( 38 ) which extends inside the shell ( 32 ), the shroud support ( 38 ) comprising an external crown ( 44 ) and an internal crown ( 42 ), between which there is arranged an air passage, the internal crown ( 42 ) of the shroud support ( 38 ) being arranged in continuation of the hub ( 40 ) of the wheel.

5. The wheel assembly according to the claim 4 , wherein the air circulation channel ( 50 ) is delimited between an external wall and an internal wall, the external wall of the channel ( 50 ) being formed successively along the axis (X-X′) by an internal wall ( 52 ) of the shell ( 32 ), by the external crown ( 44 ) of the shroud support ( 38 ) and by the internal wall ( 54 ) of the protection element ( 10 ), the internal wall of the channel ( 50 ) being formed successively along the axis (X-X′) by the internal crown ( 42 ) of the shroud support ( 38 ), and the skirt ( 21 ) of the rotor ( 14 ).

6. The wheel assembly according to claim 2 , wherein the rotor ( 14 ) of the fan ( 6 ) is positioned in the air circulation channel ( 50 ), at an axial position such that the rotor ( 14 ) is opposite the internal wall ( 54 ) of the protection element ( 10 ).

7. The wheel assembly according to the claim 6 , wherein the passage delimited by the internal crown ( 42 ) and external crown ( 44 ) extends in continuation of the space which contains the blades ( 22 ) and which is delimited between the skirt ( 21 ) and the collar ( 24 ).

8. The wheel assembly according to claim 7 , wherein the ends of the passage delimited by the internal crown ( 42 ) and external crown ( 44 ) positioned opposite the skirt ( 21 ) and the collar ( 24 ) have tangents parallel with the axis (X-X′).

9. The wheel assembly according to claim 1 , wherein the rotor ( 14 ) is configured to rotate at a rotation speed of approximately 3500 rpm.

10. A ventilation device ( 5 ) which is capable of being mounted on a wheel ( 2 ) having an axis (X-X′) in order to obtain a wheel assembly according to claim 2 , wherein the device comprises a shroud ( 8 ) whose structure is reinforced by a shroud support ( 38 ), and a protection element ( 10 ) which is fitted to the shroud ( 8 ), the external diameter of the protection element ( 10 ) being capable of accommodating the rotor ( 14 ) of the fan ( 6 ), and in that the operational clearance ( 56 ) is provided between the collar ( 24 ) of the rotor ( 14 ) and the internal wall ( 54 ) of the protection element ( 10 ).