Purge valve for mounted assembly

1. A purge valve for a mounted assembly for a vehicle consisting of a wheel comprising a rim and of a tire, the valve comprising:

a body positioned into the rim; and

a piston able to move with respect to said body between a closed position and a purge position, the valve being normally closed, and the piston being configured to be movable into a space radially external to the rim in order to open the valve,

wherein opening of the valve is obtained by action of a control force on the piston, exerted from a space radially internal to the rim, and provided at least in part by compressed air led from the space radially internal to the rim to a radially interior surface of the piston, and

wherein the compressed air led from the space radially internal to the rim to the radially interior surface of the piston is at a pressure lower than or equal to that of the mounted assembly.

2. The purge valve according to claim 1 , wherein the ratio of the area of the control surface to the area of the radially exterior surface of the piston is greater than or equal to 110%.

3. The purge valve according to claim 1 , wherein the control force is increased by a mechanical and/or hydraulic and/or electrical device.

4. The purge valve according to claim 1 , wherein, in its open position, the valve creates an annular discharge section within the space radially external to the rim in the tire cavity.

5. The purge valve according to claim 1 , wherein the valve releases the air into the space radially internal to the rim through at least one orifice.

6. The purge valve according to claim 5 , wherein the orifice has at least one characteristic dimension shorter than 10 mm.

7. The purge valve according to claim 1 , wherein the valve comprises a control system for moving the piston into the purge position as soon as the tire pressure exceeds a threshold pressure.

8. The purge valve according to claim 7 , comprising a compressible means ensuring the normally-closed position, and a control system of the passive type and in that the tire pressure keeps the valve open until a pressure defined by the compressible means is reached.

9. The purge valve according to claim 7 , wherein the valve comprises a control system of the active type, and the tire pressure keeps the valve open via an operator control.

10. The purge valve according to claim 1 , for a mounted assembly for a vehicle of the dumper type.

11. A method of deflating a mounted assembly consisting of a wheel comprising a rim and of a tire, for a vehicle, using a purge valve comprising a body positioned into the rim and a piston, having a radially interior surface, able to move with respect to the body between a closed position and a purge position, the valve being normally closed, the method comprising the steps of:

opening the valve by the action of a control force, exerted from a space radially internal to the rim, and provided at least in part by compressed air led from the space radially internal to the rim to the radially interior surface of the piston, the opening of the valve including moving the piston into a space radially external to the rim, and

wherein the compressed air led from the space radially internal to the rim to the radially interior surface of the piston is at a pressure lower than or equal to that of the mounted assembly.