Pneumatic wheel for motor vehicles
AssigneeIndustrie Pirelli S.p.A.
InventorsGiorgio Tangorra, Giovanni Calori
Life of this patent
Estimating the term…
Abstract
The beads of a pneumatic tire having sidewalls of a cross-sectional shape, wherein upon inflation the midline thereof between the tread reinforcement and bead is convex with respect to the interior of the tire, are gripped by a rim having an annular channel generally elliptically shaped in cross-section and having its open side directed radially outwardly with respect to the axis of the wheel and inwardly directed annular flanges only partially closing the open side of the channel.
Claims19
A pneumatic wheel for motor vehicles comprising a rim and a pneumatic tire with a tread reinforced by an annular inextensible structure, two sidewalls having their own section midline in the meridian plane with its convexity directed towards the inside of the tire and such that in consequence of te inflation air they are subjected to combined bending and compression stresses, said sidewalls terminating in two beads connecting the pneumatic tire to the rim, said rim having at least one seat having the shape of a circumferential channel with an opening directed in a radially outer direction with respect to the axis of rotation of the pneumatic wheel, the radially outermost ends of said rim being directed towards the midline of the pneumatic wheel to constitute said opening, the width of said opening being smaller than the maximum width of said seat, said beads having a size with respect to said seat which adapts them to be subjected to an axial compression, said beads having respectively two circumferential surfaces axially facing each other, each surface having a first radially innermost zone and a second radially outermost zone, the axial distance, when the beads are not locked in the rim seat, between said first zones being smaller than that between said second zones, the axial compression corresponding to said first radially innermost zone being greater than that corresponding to said second radially outermost zone when the beads are locked in said seat, whereby the center of the axial thrust of the beads is radially inward with respect to that which would be obtained if the axial compression were uniformly distributed on said circumferential surfaces axially facing each other.
In a rim and pneumatic tire assembly for a vehicle comprising a rim and a pneumatic tire having a reinforced tread having a given width and side edges and two sidewalls comprising elastomeric material extending from said tread side edges and terminating in beads for a rigid wheel rim, wherein said given width of the tread is wider than any other part of the tire and is reinforced over substantially the whole of its width by an annular structure which is substantially inextensible under the tire inflation pressure in both its circumferential and lateral directions, and wherein said sidewalls have a cross-sectional shape whose midline over substantially the whole length between the side edges of the tread reinforcement and the bead is convex with respect to the interior of the tire under the tire inflation pressure, each of said sidewalls having a bending stiffness, curvature of thickness sufficient to constrain the sidewall between said side edges of the inextensible tread reinforcement and the bead seat on the wheel rim whereby on inflation of the tire and under service conditions the sidewalls are placed under compressive stress, the improvement wherein the said rim comprises two symmetrical rings adapted to be detachably secured together, a substantially arcuate shaped flange which flares outwardly from the ring and then projects inwardly towards the median line of the rim, said flanges when the rings are secured together enclosing an annular channel which is substantially elliptical in cross-section and compressing the beads of said tire therein, said beads having a cross-sectional configuration when compressed in the channel with their facing surfaces disposed against each other which corresponds to the configuration of the channel, each of said facing surfaces having an annular groove therein which is directly opposite the other and divides the bead into radially inner and outer zones, said beads when disposed in the rim channel prior to compression by the rim having been disposed with respect to each other with their radially outer zones spaced farther apart than their radially inner zones.
A rim and pneumatic tire assembly for a vehicle comprising a pneumatic tire having a reinforced tread having a given width and side edges and two sidewalls comprising elastomeric material extending from said tread side edges and terminating in beads for a rigid wheel rim, said given width of the tread being wider than any other part of the tire and reinforced over substantially the whole of its width by an annular structure which is substantially inextensible under the tire inflation pressure in both its circumferential and lateral directions, said sidewalls having a cross-sectional shape whose midline over substantially the whole length between the side edges of the tread reinforcement and the bead is convex with respect to the interior of the tire under the tire inflation pressure, each of said sidewalls having a bending stiffness, curvature of thickness sufficient to constrain the sidewall between said side edges of the inextensible tread reinforcement and the bead seat on the wheel rim whereby on inflation of the tire and under service conditions the sidewalls are placed under compressive stress, said rim comprising two symmetrical rings adapted to be detachably secured together, a substantially arcuate shaped flange which flares outwardly from the ring and then projects inwardly towards the median line of the rim, said flanges when the rings are secured together enclosing an annular channel, said beads having facing surfaces, facing annular grooves in said surfaces which divide the beads into radially outer and radially inner zones, the cross-sections of the radially outer zones being thinner than the cross-sections of the radially inner zones whereby prior to compression by the rim, the facing surfaces of the outer zones are spaced apart when the facing surfaces of the inner zones are touching and, when the beads are locked in the rim under compression, the radially inner zones are under greater compression than the radially outer zones.
Dependencies are inferred from the claim text.