Safety support with improved endurance
A safety support includes a substantially cylindrical base configured to conform to the rim. The support further includes a crown with a radially outer wall configured to enter into contact with an internal wall of a crown of the tire in the event of a loss of pressure and to leave clearance therebetween at the rated operating pressure of the tire. The safety support further includes an annular body linking the base and the crown of the support. An envelope of the radially outer wall of the support crown is defined, when the support is mounted on the rim, with f being the deflection undergone by the support mounted on the rim under a load Z, the rated load of the tire, the envelope being confined between two cylinders of revolution of radius R max and R min satisfying the following relationship: 0.2 f<R max −R min <2 f.
1. A safety support for mounting on a rim inside a tire fitted on a vehicle, to support a tread of the tire in the event of a loss of inflation pressure, the safety support comprising:
a substantially cylindrical base configured to conform to the rim;
a crown with a radially outer wall configured to enter into contact with an internal wall of a crown of the tire in the event of a loss of pressure and to leave clearance therebetween at the rated operating pressure of the tire; and
an annular body linking the base and the crown of the support;
wherein an envelope of the radially outer wall of the support crown is defined, when the support is mounted on the rim, with f being the deflection undergone by the support mounted on the rim under a load Z, the rated load of the tire, the envelope being confined between two cylinders of revolution of radius R max and R min satisfying the following relationship:
0.2 f<R max −R min <2 f.
2. The support according to claim 1 , wherein R max −R min satisfies the following relationship:
0.3 f<R max −R min <f.
3. The support according to one of claims 1 or 2 , wherein a zone of radius R min of the envelope of the radially outer wall of the support crown is disposed axially at at least one lateral end of the support crown.
4. The support according to claim 3 , wherein the zone of radius R min is disposed on a side of the support intended to be positioned on the outside of the vehicle.
5. The support according to claim 3 , wherein the envelope of the outer wall of the support crown comprises a second zone of radius R′ min , greater than or equal to R min , disposed axially on the other side of a circumferential median plane from the zone of radius R min and satisfying the relationship:
0.2 f<R max −R′ min <2 f.
6. The support according to claim 5 , wherein the zone of radius R′ min satisfies the relationship:
0.3 f<R max −R′ min <f.
7. The support according to claim 1 , wherein the support crown comprises longitudinal grooves.
8. The support according to claim 1 , wherein the envelope of the outer wall of the crown comprises, in axial section, at least one zone of substantially constant curvature.
9. The support according to claim 1 , wherein the envelope of the outer wall of the crown has, in axial section, substantially constant curvature.
10. The support according to claim 1 , wherein at least one lateral end of the envelope of the outer wall of the crown comprises a zone that is substantially a cylinder of revolution of a minimum radius of the envelope.
11. The support according to claim 1 , wherein the annular body of the support comprises a plurality of radial partitions, distributed over the circumference and extending axially on either side of a circumferential median plane, and radial junctions extending substantially circumferentially and connected at each of their ends to two adjacent ones of the radial partitions.