Tire-type device for a vehicle

Abstract

Bearing structure (6) has identical bearing elements (61) in tension outside contact patch (A) with the ground and in compression in the contact patch (A). Bearing elements (61) are filamentary and are connected to radially inner face (23) of radially outer structure of revolution (2) by radially outer fabric (71) and to radially outer face (33) of radially inner structure of revolution (3) by radially inner fabric (72), respectively. Furthermore, mean surface density D of bearing elements (61) per unit area of radially outer structure of revolution (2), expressed in 1/m.sup.2, is at least equal to (S/S.sub.E)*Z/(A*F.sub.r), where S is area, in m.sup.2, of radially inner face (23) of radially outer structure of revolution (2), S.sub.E is connecting area, in m.sup.2, of radially outer fabric (71) with radially inner face (23) of radially outer structure of revolution (2), Z is nominal radial load, in N, A is area of contact with the ground, in m.sup.2, and F.sub.r is the force at break, in N, of bearing element (61).

Claims

1. A tire device for a vehicle, comprising: a radially outer structure of revolution, an axis of revolution of which is an axis of rotation of the tire device and which is adapted to come into contact with the ground via a tread comprising at least one elastomeric material, the radially outer structure of revolution having two axial ends and a radially inner face having an area S, and the radially outer structure of revolution comprising a circumferential reinforcement; a radially inner structure of revolution that is coaxial with the radially outer structure of revolution and is configured to ensure a connection of the tire device with a means for mounting on the vehicle, the radially inner structure of revolution having two axial ends and a radially outer face, and the radially inner structure of revolution comprising at least one polymeric material; an inner annular space of mean radial height H that is radially delimited by the radially inner face of the radially outer structure of revolution and by the radially outer face of the radially inner structure of revolution; a bearing structure comprises a plurality of identical bearing elements that are not mechanically connected together in the inner annular space, the bearing elements extending continuously from the radially inner face of the radially outer structure of revolution to the radially outer face of the radially inner structure of revolution, such that, when the tire device is subjected to a nominal radial load Z and is in contact with flat ground via an area of contact A, the bearing elements that are connected to a portion of the radially outer structure of revolution that is in contact with the ground are made to buckle under compression and at least some of the bearing elements that are connected to a portion of the radially outer structure of revolution that is not in contact with the ground are under tension, wherein the bearing elements of the bearing structure are filamentary, wherein the bearing elements of the bearing structure are connected to the radially inner face of the radially outer structure of revolution by a radially outer fabric, at least partially covering said radially inner face over a connecting area S.sub.E, and are connected to the radially outer face of the radially inner structure of revolution by a radially inner fabric, at least partially covering said radially outer face, an assembly made up of the bearing structure, the radially outer fabric, and the radially inner fabric being a sandwich structure, wherein the mean surface density D of the bearing elements per unit area of radially outer structure of revolution, expressed in 1/m.sup.2, is at least equal to (S/S.sub.E)*Z/(A*Fr), where: S is the area, in m.sup.2, of the radially inner face of the radially outer structure of revolution, S.sub.E is the connecting area, in m.sup.2, of the radially outer fabric with the radially inner face of the radially outer structure of revolution, Z is the nominal radial load, in N, applied to the tire device, A is the area of contact with the ground, in m.sup.2, of the tire device, and Fr is the force at break, in N, of a bearing element of the plurality of identical bearing elements, and wherein the tire device comprises two sidewalls that connect, in pairs, the axial ends of the radially outer and radially inner structures of revolution, respectively, and axially delimit the inner annular space, such that the inner annular space forms a closed cavity that can be pressurized by an inflation gas.

2. The tire device according to claim 1, wherein the surface density D of the bearing elements per unit area of radially outer structure of revolution, expressed in 1/m.sup.2, is at least equal to 3*(S/S.sub.E)*Z/(A*Fr).

3. The tire device according to claim 1, wherein the surface density D of the bearing elements per unit area of radially outer structure of revolution, expressed in 1/m.sup.2, is at least equal to 6*(S/S.sub.E)*Z/(A*Fr).

4. The tire device according to claim 1, wherein the connecting area S.sub.E, in m.sup.2, of the radially outer fabric with the radially inner face of the radially outer structure of revolution is equal to the area S of the radially inner face of the radially outer structure of revolution.

5. The tire device according to claim 1, wherein the radially outer fabric is a woven fabric comprising interlacings of a first family of threads that are mutually parallel and form, with a circumferential direction of the tire device, an angle AE at least equal to 100 and at most equal to 450, and of a second family of threads that are mutually parallel, the respective threads of the first and second families of threads being symmetrical with respect to an equatorial plane of the tire device.

6. The tire device according to claim 5, wherein each said bearing element comprises at least one radially outer end portion that is integrated with the radially outer woven fabric and comprised of interlacings with respect to at least one thread of one of the first and second families of threads and parallel to the other family of threads.

7. The tire device according to claim 1, wherein the radially inner fabric is a woven fabric comprising interlacings of a first family of threads that are mutually parallel and form, with the circumferential direction of the tire device, an angle A.sub.1 substantially equal to 450, and of a second family of threads that are mutually parallel, the respective threads of the first and second families of threads being symmetrical with respect to an equatorial plane of the tire device.

8. The tire device according to claim 7, wherein the bearing elements have at least one radially inner end portion that is integrated with the radially inner woven fabric and comprised of interlacings with respect to at least one thread of one of the first and second families of threads and parallel to the other family of threads.

9. The tire device according to claim 7, wherein the sandwich structure comprises the radially outer woven fabric and the radially inner woven fabric and the identical bearing elements configured as filamentary bearing elements comprised of threads, respective end portions of which are integrated into each radially outer and radially inner fabric parallel to one of the families of threads of the fabric.

10. The tire device according to claim 1, wherein at least one of the bearing structure, the radially outer fabric, and the radially inner fabric, which comprise the sandwich structure, comprise a polymeric material, wherein the polymeric material is an aliphatic polyamide, an aromatic polyamide, a polyester, a metal material, steel, a material comprising glass or carbon, or any combination of the above materials.

11. The tire device according to claim 1, wherein at least one of the bearing structure, the radially outer fabric, and the radially inner fabric, which comprise the sandwich structure, comprise a polyester.

12. The tire device according to claim 1, wherein at least one of the bearing structure, the radially outer fabric, and the radially inner fabric, which comprise the sandwich structure, comprise an aliphatic polyamide.

13. The tire device according to claim 1, wherein the sandwich structure, comprised of the bearing structure, the radially outer fabric, and the radially inner fabric, comprises a same material.

14. The tire device according to claim 1, wherein the sandwich structure, comprised of the bearing structure, the radially outer fabric, and the radially inner fabric, is comprised of a helical winding of a strip on the radially outer face of the radially inner structure of revolution, so as to form a juxtaposition of contiguous or non-contiguous strip portions.

15. The tire device according to claim 1, wherein the sandwich structure, comprised of the bearing structure, the radially outer fabric, and the radially inner fabric, is comprised of a cylindrical winding, about the axis of revolution of the tire device, of a single element having an axial width equal to the axial width of the sandwich structure.

16. The tire device according to claim 1, wherein an angle B formed between a said bearing element with a radial direction of the tire device is substantially zero for a bearing element situated in the equatorial plane of the tire device, and is higher in absolute terms, the further a said bearing element is from the equatorial plane.

17. The tire device according to claim 1, wherein the sidewalls are not directly connected to the sandwich structure.

18. The tire device according to claim 1, wherein the circumferential reinforcement of the radially outer structure of revolution comprises at least one reinforcing layer comprising textile or metal reinforcing elements.

19. The tire device according to claim 1, wherein the radially inner structure of revolution comprises, on a radially inner face, a connecting layer configured to be fixed to the means for mounting on the vehicle.

20. A mounted assembly comprising a tire device according to claim 1 mounted on a means for mounting on the vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will be better understood with the aid of FIGS. 1 to 6 presented below:

(2) FIG. 1: perspective view in partial section of a tire-type device according to an embodiment of the invention.

(3) FIG. 2: view in circumferential section of a tire-type device according to an embodiment of the invention, in the squashed state.

(4) FIG. 3A: view in meridian section of a tire-type device according to an embodiment of the invention, in the case of a bearing structure having one-dimensional bearing elements.

(5) FIG. 3B: perspective view of a one-dimensional bearing element.

(6) FIG. 4: perspective view in partial section of a tire-type device according to a preferred embodiment of the invention, with a sandwich structure formed by helical winding of a strip.

(7) FIG. 5: front view with partial section of the tread of a tire-type device according to a preferred embodiment of the invention, with a sandwich structure formed by helical winding of a strip.

(8) FIG. 6A: view in meridian section of a sandwich structure comprising two woven fabrics and a bearing structure.

(9) FIG. 6B: top view of a sandwich structure comprising two woven fabrics and a bearing structure.

(10) FIG. 7: compared typical curves of the change in load applied as a function of deflection for a tire-type device according to an embodiment of the invention and a reference tire of the prior art.

(11) FIG. 8: compared typical curves of the change in cornering stiffness as a function of load applied for a tire-type device according to an embodiment of the invention and a reference tire of the prior art.

DETAILED DESCRIPTION OF THE DRAWINGS

(12) FIG. 1 shows a perspective view in partial section of a tire-type device 1 according to the invention, mounted on a mounting means 4 or rim, and comprising a radially outer structure of revolution 2 having a radially inner face 23 and two axial ends 24, a radially inner structure of revolution 3 having a radially outer face 33 and two axial ends 34, an inner annular space 5, a sandwich structure 8 comprising a bearing structure 6, a radially outer fabric 71 and a radially inner fabric 72, and two sidewalls 9. The radially outer structure of revolution 2 has an axis of revolution which is the axis of rotation YY of the tire-type device and is intended to come into contact with the ground via a tread 21 comprising at least one elastomeric material. Moreover, the radially outer structure of revolution 2 comprises a circumferential reinforcement 22 which, in the present case, is made up of a single reinforcing layer. The radially inner structure of revolution 3, which is coaxial with the radially outer structure of revolution 2, is intended to ensure the connection of the tire-type device 1 with the mounting means 4. The radially inner structure of revolution 3 comprises at least one polymeric material, most frequently an elastomer compound. The inner annular space 5 is radially delimited by the radially outer 2 and radially inner 3 structures of revolution, respectively. According to the invention, the bearing structure 6 is made up of a plurality of bearing elements 61 that extend continuously from the radially inner face 23 of the radially outer structure of revolution 2 to the radially outer face 33 of the radially inner structure of revolution 3 and are independent in pairs in the inner annular space 5. The radially outer fabric 71 and radially inner fabric 72 of the sandwich structure 8 are connected, and usually bonded, to the radially inner face 23 of the radially outer structure of revolution 2 and to the radially outer face 33 of the radially inner structure of revolution 3, respectively. Finally, the tire-type device 1 comprises two sidewalls 9 that connect the axial ends (24, 34) of the radially outer 2 and radially inner 3 structures of revolution, respectively, and axially delimit the inner annular space 5, such that the inner annular space 5 forms a closed cavity that can be pressurized by an inflation gas.

(13) FIG. 2 shows a circumferential section of a tire-type device 1 according to the invention, mounted on a mounting means 4, in its squashed state, that is to say subjected to a nominal radial load Z. The bearing structure 6 is made up of a plurality of filamentary bearing elements 61 that extend continuously from the radially outer structure of revolution 2 to the radially inner structure of revolution 3 and are independent in pairs in the inner annular space 5. The tire-type device 1, subjected to a nominal radial load Z, is in contact with flat ground by way of an area of contact A, having a circumferential length X.sub.A. The bearing elements which are connected to that portion of the radially outer structure of revolution 2 that is in contact with the ground are made to buckle under compression, while at least some of the bearing elements that are connected to that portion of the radially outer structure of revolution 2 that is not in contact with the ground are under tension.

(14) FIG. 3A shows a meridian section of a tire-type device 1 according to the invention, mounted on a mounting means 4. As described for FIG. 1, the tire-type device 1 comprises a radially outer structure of revolution 2 having a radially inner face 23 and two axial ends 24 and comprising a tread 21 and a reinforcement 22, a radially inner structure of revolution 3 having a radially outer face 33 and two axial ends 34, an inner annular space 5, a sandwich structure 8 comprising a bearing structure 6 having filamentary bearing elements 61, a radially outer fabric 71 and a radially inner fabric 72, and two sidewalls 9. The tire-type device 1, subjected to a nominal radial load Z, is in contact with flat ground by way of an area of contact A. As seen above, the bearing elements 61 that are positioned on the opposite side from the contact patch are under tension, while the bearing elements 61 that are connected to that portion of the radially outer structure of revolution 2 in contact with the ground are made to buckle under compression.

(15) FIG. 3B shows a filamentary or one-dimensional bearing element 61 having a circular mean section S.sub.P that is defined by a smallest characteristic dimension E and a largest characteristic dimension L that are both equal, in the example shown, to the diameter of the circle, and is characterized by its aspect ratio K equal to L/E, and thus equal to 1 in the present case. Moreover, the smallest characteristic dimension E of the mean section S.sub.P of the bearing element 61, that is to say, in the present case, its diameter, is at most equal to 0.02 times the mean radial height H of the inner annular space 5. The bearing element 61 has a length L.sub.P at least equal to the mean height H of the inner annular space 5.

(16) FIG. 4 shows a perspective view in partial section of a tire-type device 1 according to a preferred embodiment of the invention in which the sandwich structure 8, made up of the bearing structure 6, the radially outer fabric 71 and the radially inner fabric 72, is made up of a helical winding of a strip 81 on the radially outer face 33 of the radially inner structure of revolution 3, so as to form a juxtaposition of strip portions. The other elements referenced in FIG. 4 are identical to those in FIG. 1.

(17) FIG. 5 shows a front view with partial section of the tread of a tire-type device 1 according to the preferred embodiment of the invention, shown in perspective with partial section in FIG. 4. FIG. 5 is a view with partial removal of the tread 2, revealing the helical winding of a strip 81 on the radially outer face 33 of the radially inner structure of revolution 3 so as to form a juxtaposition of strip portions. This helical winding of a strip 81 forms the sandwich structure 8, made up of the bearing structure 6, the radially outer fabric 71 and the radially inner fabric 72.

(18) FIG. 6A is a view in meridian section of a sandwich structure 8 comprising two woven fabrics (71, 72) and a bearing structure 6. The two woven fabrics (71, 72) are intended to become the radially outer fabric and radially inner fabric, respectively, following integration into the tire-type device. Each woven fabric (71, 72) consists of perpendicular interlacings of a first family of threads (711, 721), known as weft threads, and a second family of threads (712, 722), known as warp threads. Moreover, the bearing elements 61 of the bearing structure 6 are made up of continuous threads connecting the two woven fabrics (71, 72) and comprising portions (611, 612) which are interlaced with the respective weft threads (711, 721) of said woven fabrics (71, 72), are parallel to the warp threads (712, 722) and form the ends of the bearing elements 61 integrated into each fabric. The advantage of such a design is that it is possible to weave the sandwich structure in one step.

(19) FIG. 6B shows a top view of a sandwich structure 8 comprising two woven fabrics (71, 72) and a bearing structure 6. The woven fabric 71 shown consists of perpendicular interlacings of the first family of threads 711, known as weft threads, and the second family of threads 712, known as warp threads. Moreover, FIG. 6B shows portions of threads 611 which are interlaced with the weft threads 711, are parallel to the warp threads 712 and form ends of the bearing elements 61 integrated into the woven fabric 71.

(20) FIG. 7 shows two compared typical curves of the change in load applied Z, expressed in daN, as a function of deflection F, expressed in mm, for a tire-type device according to the invention I and a reference tire R of the prior art. This figure shows that, for a given radial load Z, the deflection F of a tire-type device according to the invention I is less than that of the reference tire R. In other words, the radial stiffness of the tire-type device I is greater than the radial stiffness of the reference tire R.

(21) FIG. 8 shows two compared typical curves of the change in cornering stiffness, expressed in N/, as a function of the load applied, expressed in N, for a tire-type device according to the invention and a reference tire of the prior art. This figure shows that, for a given radial load Z, the cornering stiffness Z of a tire-type device according to the invention I is greater than that of the reference tire R.

(22) The invention has been studied more particularly as an alternative solution to a conventional tire for a passenger vehicle.

(23) The tire-type device studied, the stiffness characteristics of which are shown in FIGS. 5 and 6 described above, comprises a radially outer structure of revolution and a radially inner structure of revolution having respective mean radii equal to 333 mm and 289 mm, and axial widths that are both equal to 250 mm. The inner annular space, radially delimited by the radially outer and radially inner structures of revolution, respectively, has a mean radial height H equal to 35 mm. The sandwich structure made up of the bearing structure, the radially outer fabric and the radially inner fabric is made of polyethylene terephthalate (PET). Each filamentary bearing element of the bearing structure, made of polyethylene terephthalate (PET), has a mean section S.sub.P equal to 7*10.sup.8 m.sup.2 and a stress at break F.sub.r/S.sub.P equal to 470 MPa. The surface density D of the bearing elements per unit area of radially outer structure of revolution is equal to 85 000 threads/m.sup.2. The tire-type structure, inflated to a pressure P of between 1.5 bar and 2.5 bar, is subjected to a radial load Z equal to 600 daN.

(24) Although the invention describes a bearing structure made up of filamentary bearing elements that are identical in terms of aspect ratio K, structure and material, the invention can be extended to a bearing structure which may be made up of any combination of bearing elements, such as, for example: filamentary bearing elements having different aspect ratios K and/or structures and/or materials, filamentary bearing elements distributed in a non-uniform density in the axial direction and/or in the circumferential direction, this list not being exhaustive.

(25) The scope of protection of the invention is not limited to the examples given hereinabove. The invention is embodied in each novel characteristic and each combination of characteristics, which includes every combination of any features which are stated in the claims, even if this feature or combination of features is not explicitly stated in the examples.