Collapsible tire, method for collapsing same, and use thereof

Abstract

The collapsible tire includes at least one carcass reinforcement that is surmounted radially from the outside by an inextensible crown reinforcement, which is radially on an inside of a tread. The reinforcements each include at least one layer of reinforcing elements. The tread is connected to two beads by two sidewalls. The beads are intended to come into contact with a rim, and each bead has at least one circumferential reinforcing element called a bead wire. The bead wire defines a mean line which forms a substantially circular closed curve in a circumferential plane. The bead wires are flexible and have at least one concave part P.sub.c with a radius R.sub.c and a center of curvature C.sub.c.

Claims

1. A collapsed tire for a vehicle, comprising: a carcass that has a width which is at least 175 mm, at least one carcass reinforcement associated with an inextensible crown reinforcement, the at least one carcass reinforcement being disposed radially on the inside of a tread, the reinforcements each comprising at least one layer of reinforcing elements, the tread being connected to two beads by two sidewalls, the beads being intended to come into contact with a rim, each bead comprising at least one inextensible circumferential reinforcing element called a bead wire, the sidewalls having a thickness between 2.6 and 7 mm and the crown reinforcement having a thickness between 2 and 7 mm, wherein the bead wire of each bead is flexible, and a mean line of each bead wire extending through a non-overlapping, closed-loop and non-circular shape in a circumferential plane, and said non-overlapping, closed-loop and non-circular shape defining at least one concave part (P.sub.c) with a radius (R.sub.c) with a center of curvature (C.sub.c).

2. The tire according to claim 1, wherein the mean line of each bead wire further defines at least two points of inflexion (I.sub.1, I.sub.2) delimiting the at least one concave part (P.sub.c).

3. The tire according to claim 1, wherein the closed-loop, non-circular shape of each mean line of each bead wire approximates an S-shape which has two convex parts (P.sub.x1, P.sub.x2) having two radii (R.sub.x1, R.sub.x2) and having two centers of curvature (C.sub.x1, C.sub.x2), and wherein straight lines (D.sub.1, D.sub.2) respectively connect the center of curvature (C.sub.c1) of the concave part (P.sub.c) to each of the centers of curvature (C.sub.x1, C.sub.x2) of the convex parts (P.sub.x1, P.sub.x2) and wherein the straight lines (D.sub.1, D.sub.2) are angled relative to one another at an angle α that is between 30° and 125°.

4. The tire according to claim 1, wherein the mean line of the bead wire of each bead is formed by winding a metal cord, formed of filaments, which is saturated and unwrapped, wherein the diameter of the cord is less than 1.5 mm and wherein the diameter of the filament is less than 0.25 mm.

5. The tire according to claim 1, wherein the closed-loop, non-circular shape of each mean line of each bead wire approximates an S-shape which has two convex parts (P.sub.x1, P.sub.x2), respectively with smaller radii (R.sub.x1, R.sub.x2) than the radius (R.sub.c) of the at least one concave part (P.sub.c), and having centers of curvature (C.sub.x1, C.sub.x2), and wherein straight lines (D.sub.1, D.sub.2) respectively connect the center of curvature (C.sub.c1) of the concave part (P.sub.c) to each of the centers of curvature (C.sub.x1, C.sub.x2) of the convex parts (P.sub.x1, P.sub.x2) and wherein the straight lines (D.sub.1, D.sub.2) are angled relative to one another at an angle α that is between 40 and 140°.

6. A plurality of the collapsed tires set forth in claim 1, wherein when stored, the tires occupy a volume that is less than 65% by comparison with a lacing mode of packaging tires.

7. A method for collapsing a tire with at least one carcass reinforcement associated with an inextensible crown reinforcement, a carcass with a width that is at least 175 mm, the at least one carcass reinforcement being disposed radially on the inside of a tread, the reinforcements each comprising at least one layer of reinforcing elements, the tread being connected by two beads by two sidewalls, the beads being intended to come into contact with a rim, each bead comprising at least one inextensible circumferential reinforcing element called a bead wire, and the sidewalls having a thickness between 2.6 and 7 mm and the crown reinforcement having a thickness between 2 and 7 mm, comprising the steps of: parting, in a radial plane, the beads of a part of the tire along an axial direction towards an axis tangential to the center of the tread of the tire in the said radial plane, applying a force in a radial direction to the said tread so as to move the tread closer to a cavity opposite the force to collapse the tire into the shape of a double-walled arc of a circle comprising a base that is connected with two axes such that a mean line of each bead wire extends through a non-overlapping, closed-loop and non-circular shape in a circumferential plane and defines at least one concave part (P.sub.c) with a radius (R.sub.c) and with a center of curvature (C.sub.c).

8. A method for collapsing a tire with at least one carcass reinforcement associated with an inextensible crown reinforcement, a carcass with a width that is at least 175 mm, the at least one carcass reinforcement being disposed radially on the inside of a tread, the reinforcements each comprising at least one layer of reinforcing elements, the tread being connected by two beads by two sidewalls, the beads being intended to come into contact with a rim, each bead comprising at least one inextensible circumferential reinforcing element called a bead wire, and the sidewalls having a thickness between 2.6 and 7 mm and the crown reinforcement having a thickness between 2 and 7 mm, comprising the steps of: parting, in a radial plane, the beads of a first part of the tire along an axial direction towards an axis tangential to the center of the tread, applying a first force (F1) in a first circumferential direction to the said tread so as to move a corresponding cavity closer to another part of the cavity of the tire, parting, in a radial plane, the beads of a second part of the tire in an axial direction towards an axis tangential to the center of the tread, applying a compression force in the radial direction to the said first and/or second part, and a second force (F2) in a second circumferential direction, of opposite sense to the said first force (F1) to the said tread so as to move the corresponding cavity closer to another part of the cavity of the tire such that a mean line of each bead wire extends through a non-overlapping, closed-loop and non-circular shape in a circumferential plane and defines at least one concave part (P.sub.c) with a radius (R.sub.c) and with a center of curvature (C.sub.c), and continuing to apply the compression force until the non-overlapping, closed-loop and non-circular shape of the mean line of each bead wire when the tire is collapsed is a double-walled arc shape or an S-shape.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The various measurements that follow have been taken on tires, collapsed according to the invention, of different sizes.

(2) FIG. 1 depicts a schematic view in section on a radial plane, of half a tire in the uncollapsed state,

(3) FIG. 2 depicts a schematic view in cross section on a circumferential plane of the collapsed tire of the invention according to a first embodiment,

(4) FIG. 3 depicts a schematic view in cross section on a circumferential plane of the collapsed tire of the invention according to a second embodiment,

(5) FIG. 4 depicts a schematic view in cross section on a circumferential plane, of the collapsed tire according to the invention, according to a third embodiment,

(6) FIGS. 5A and 5B depict a schematic three-dimensional view of the various steps of a first method of collapsing, and

(7) FIGS. 6A and 6B depict a schematic three-dimensional view of the various steps of a second method of collapsing.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

(8) FIG. 1 depicts a passenger vehicle tire, of general reference 1, in the uncollapsed state, comprising a tread 2 extended radially inwards by two sidewalls 8 connected to two beads 6, the said beads comprising a bead wire 3 (reinforcing element) (not depicted).

(9) FIG. 1 depicts a tread 2 radially furthest towards the outside. Radially on the inside of the said tread 2 there are, in succession, an inextensible crown reinforcement 4 and a carcass reinforcement 5.

(10) The said crown 4 and carcass 5 reinforcements are each made up of at least one layer of reinforcing elements (not depicted). The tread 2 is connected to two beads 6 by two sidewalls 8. Each bead 6 comprises at least one bead wire 3. This bead wire 3, which defines a mean line forming a substantially circular closed curve in a circumferential plane is inextensible and flexible.

(11) The bead wire is preferably made of steel, and takes the form of a saturated and unwrapped cord formed of filaments; the said filaments being of a diameter equal to 0.18 mm. The cord is a 19.18 metal cord of formula 1+6+12, the layers being formed with the same direction of rotation and with identical pitches equal to 10 mm. Such a cord can be used to form a bead wire by winding 3 to 16 turns. The number of turns required is dependent on the size of the tire and its use.

(12) The mean thickness E.sub.F of the sidewall of the tire according to the invention, measured at the point located in the middle, in the radial direction, between the high point of the bead wire and the low point of the tire on the equatorial plane, is comprised between 2.6 and 7 mm.

(13) The mean thickness E.sub.S of the crown reinforcement 4, measured in the equatorial plane, is comprised between 2 and 7 mm.

(14) In FIG. 2, the mean line of the bead wire 3 (depicted in dotted line) of the tire, of trade reference 185/65 R 14, collapsed according to a first mode of collapse, roughly into a U shape, has a concave part P.sub.c1 of smaller radius R.sub.c1 equal to 69 mm and a center of curvature C.sub.c1.

(15) The mean line of the bead wire 3 comprises, on the one hand, two points of inflexion I.sub.1, I.sub.2 which delimit the concave part P.sub.c1 and, on the other hand, two convex parts P.sub.x1, P.sub.x2 having two smaller radii R.sub.x1 equal to 18 mm and R.sub.x2 equal to 18 mm and two centers of curvature C.sub.x1 and C.sub.x2.

(16) Two straight lines D.sub.1 and D.sub.2 which respectively connect the center of curvature C.sub.c1 and concave part P.sub.c1 to each of the centers of curvature C.sub.x1 and C.sub.x2 of the convex part P.sub.x1 form an angle α of around 52°. In this mode of collapse the straight lines D.sub.1 and D.sub.2 are substantially the same length, and measure 170 mm.

(17) In another alternative form of this same mode of collapse according to FIG. 2 of the tire of the same reference as previously, the two straight lines D.sub.1 and D.sub.2 which respectively connect the center of curvature C.sub.c1 of the concave part P.sub.c1 to each of the centers of curvature C.sub.x1, C.sub.x2 of the convex part P.sub.x1, have different lengths. D.sub.1 is equal to 197 mm, D.sub.2 is equal to 135 mm; the ratio D.sub.1/D.sub.2 is equal to 1.45 and the angle α is equal to 65°.

(18) Having been collapsed according to this first mode of collapse, the tires can also be nested in one another or even possibly laced. Lacing makes it possible to keep them compressed.

(19) Table I below collates other measurements taken on the form of collapse depicted in FIG. 2.

(20) TABLE-US-00001 TABLE I Sidewall Crown thickness reinforcement Angle D.sub.1 D.sub.2 R.sub.c1 R.sub.x1 R.sub.x2 Size of (in mm) thickness α (in (in (in (in (in (in tire E.sub.F (in mm) E.sub.S degrees) mm) mm) mm) mm) mm) D.sub.1/D.sub.2 175/70 3.7 3.2 51 138 138 77 16 16 1 R 13 185/65 4.5 2.7 61 170 170 68 18 18 1 R 14 185/65 4.5 2.7 65 197 135 69 17 17 1.45 R 14 195/65 4.8 3.7 124 156 156 111 30 30 1 R 15 205/55 5 3.7 55 168 168 78 18 18 1 R 16 225/55 5 3.2 45 189 189 96 16 16 1 R 17

(21) The collapsing of the tire 1 as depicted in FIG. 3 differs from that of FIG. 2 in that the straight lines D.sub.1 and D.sub.2 form an angle α comprised between 38° and 57°, and in that they do not have the same length. The collapsing as depicted in FIG. 4 closely resembles the shape of a spiral.

(22) The volume occupied by the tire is less than 85%, preferably less than 75% of the volume occupied by tires collapsed according to the currently known modes of packaging.

(23) Table II below collates the measurements taken on various tires according to the form of collapse depicted in FIG. 3.

(24) TABLE-US-00002 TABLE II Sidewall Crown thickness reinforcement Angle D.sub.1 D.sub.2 R.sub.c1 R.sub.x1 R.sub.x2 Size of (in mm) thickness α (in (in (in (in (in (in tire E.sub.F (in mm) E.sub.S degrees) mm) mm) mm) mm) mm) D.sub.1/D.sub.2 175/70 3.7 3.2 42 125 83 29 19 19 1.50 R 13 185/65 4.5 2.7 38 135 83 25 15 15 1.63 R 14 195/65 4.5 2.7 42 136 93 26 16 16 1.46 R 15 205/55 4.8 3.7 37 154 94 27 17 17 1.64 R 16 225/55 5 3.7 46 149 110 24 14 14 1.35 R 17

(25) The third mode of collapsing the tire 1, as depicted in FIG. 4, differs from that of FIG. 2 in that the mean line of the bead wire 3 comprises two concave parts P.sub.c1, P.sub.c2. The concave parts P.sub.c1 and P.sub.c2 are characterized by a smaller radius.

(26) The mean line of the bead wire 3 also comprises two convex parts P.sub.x1, P.sub.x2 respectively having a smaller radius R.sub.x1 equal to 11 mm, and R.sub.x2 equal to 11 mm, and respectively having a center of curvature C.sub.x1, C.sub.x2.

(27) In FIG. 4, the mean line of the bead wire 3 comprises three points of inflexion I.sub.1, I.sub.2 and I.sub.3 which delimit a concave part from a convex part and vice versa.

(28) According to this third mode of collapse, the straight lines D.sub.1 and D.sub.2 which respectively connect the center of curvature C.sub.c1 of a concave part P.sub.c1 to each of the centers of curvature C.sub.x1, C.sub.x2 of the convex parts P.sub.x1 and P.sub.x2 form an angle α comprised between 95° and 125°. The straight lines D.sub.1 and D.sub.2 are not of the same length.

(29) The volume occupied by the tire is less than 80%, preferably less than 70% by comparison with the volume occupied by tires collapsed according to currently known modes of compacting.

(30) Table III below collates the measurements taken on various tires according to the form of collapse depicted in FIG. 4.

(31) TABLE-US-00003 TABLE III Sidewall Crown thickness reinforcement Angle D.sub.1 D.sub.2 R.sub.c1 R.sub.x1 R.sub.x2 Size of (in mm) thickness α (in (in (in (in (in (in tire E.sub.F (in mm) E.sub.S degrees) mm) mm) mm) mm) mm) D.sub.1/D.sub.2 175/70 3.7 3.2 112 122 92 20 10 10 1.33 R 13 185/65 4.5 2.7 111 132 96 21 11 11 1.37 R 14 195/65 4.5 2.7 112 136 103 25 15 15 1.32 R 15 205/55 4.8 3.7 106 159 89 22 12 12 1.78 R 16 225/55 5 3.7 112 153 112 22 12 12 1.36 R 17

(32) In order to obtain a collapsed tire according to the invention, there are two conceivable methods of collapsing.

(33) The first method of collapsing results in the collapsed tire according to the invention indicated schematically in FIGS. 2 and 3. This method is indicated schematically in FIGS. 5A and 5B. As FIG. 5A shows, this method consists, in a radial plane, in parting the beads 6 towards an axis tangential to the center 2a of the tread 2 in the said radial plane.

(34) FIG. 5B shows that, in a radial direction, a force is applied to the said tread 2 either at the same time as the parting step and/or afterwards, so as to move this tread closer to the cavity 9 opposite. This then yields, in a circumferential plane, a tire that is collapsed substantially into the shape of semicircle and closely resembles a U shape. This shape in the form of an arc of a circle comprises two substantially vertical axes 10a and 10b which, when bent over on one another indiscriminately, yield the collapsed configuration of FIG. 3 which closely resembles a spiral.

(35) The second method of collapsing the tire results in the collapsed tire according to the invention indicated schematically in FIG. 4.

(36) This method is indicated schematically by FIGS. 6A and 6B. According to this second method of collapse, and as shown in FIG. 6A, the beads 6 of a first part 11 of the tire are, in a radial plane, parted in an axial direction towards an axis tangential to the center 2a of the tread 2. Also, the beads 6 of the second part 12 of the tire are, in a radial plane, parted in an axial direction towards an axis tangential to the center 2a of the tread 2.

(37) A compression force is applied in a radial direction to said tread 2 of the first part 11. The said force may be applied at the same time as the beads 6 are being parted and/or afterwards.

(38) As FIG. 6B shows, a first compression force F.sub.1 is applied, simultaneously or otherwise, in a first circumferential direction X.sub.1-X.sub.1′ to the tread 2 in order to move it closer to the cavity 13 opposite. As FIG. 6B also shows a second compression force F.sub.2 is applied, simultaneously or otherwise, in a second circumferential direction X.sub.2-X.sub.2′.

(39) A second force F.sub.2 is applied in a second circumferential direction parallel to the first force F.sub.1, so as to move it closer to the cavity 14. The forces F.sub.1 and F.sub.2 are of opposite sense.

(40) The compression force applied in the radial direction may be applied simultaneously with the second force F.sub.2 or non-simultaneously therewith.

(41) The tire collapsed according to this mode of collapse is more or less S-shaped.