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US-12617236-B2 - Deformable wheel with non-pneumatic load bearing for lunar and martian conditions

US12617236B2US 12617236 B2US12617236 B2US 12617236B2US-12617236-B2

Abstract

A deformable wheel with non-pneumatic load bearing intended to equip a vehicle for rolling under extreme conditions such as those encountered on the moon and on Mars, includes a hub, a laminated annular strip including a plurality of concentric ferrules which are assembled with the interposition of interposing layers each composed of a material whose Young's modulus is 600,000 to 1,000 times lower than that of the ferrules, and a plurality of metal cables. Each cable connects the hub to the laminated strip while being fixed, on the one hand by an external end to the laminated strip, and on the other hand by an internal end to the hub by means of an elastic member making it possible to modulate the radial stiffness of the cables. Each elastic member is associated with an abutment able to limit its deformation.

Inventors

  • Antonio Delfino
  • David F. OLSOMMER

Assignees

  • VENTURI LAB SA

Dates

Publication Date
20260505
Application Date
20230829
Priority Date
20220829

Claims (17)

  1. 1 . A deformable wheel with non-pneumatic load bearing intended to equip a vehicle for rolling under extreme conditions, the wheel comprising: a hub, a laminated annular strip configured to be in contact with soil, positioned around the hub which is concentric therewith and comprising a plurality of concentric ferrules which are assembled with interposition of interposing layers each composed of a material whose Young's modulus is 600,000 to 1,000 times lower than that of the ferrules, and a plurality of metal cables having an outer diameter between 0.2 mm and 5 mm, each cable radially connecting the hub to the laminated strip while being fixed by an external end to the laminated strip and by an internal end to the hub by means of an elastic member to modulate radial stiffness of the cables, each elastic member being associated with an abutment configured to limit deformation.
  2. 2 . The wheel according to claim 1 , wherein the ferrules of the laminated strip are made of metal or of composite material.
  3. 3 . The wheel according to claim 1 , wherein the interposing layers of the laminated strip are composed of a hyperelastic elastomer having a glass transition temperature below 120° C.
  4. 4 . The wheel according to claim 1 , wherein the cables have a ratio between tensile mechanical stiffness (Kt) and compressive mechanical stiffness (Kc) between 25,000 and 300,000.
  5. 5 . The wheel according to claim 4 , wherein the ratio between the tensile mechanical stiffness (Kt) and the compressive mechanical stiffness (Kc) of the cables is between 25,000 and 150,000.
  6. 6 . The wheel according to claim 1 , wherein each cable is inclined with respect to a plane (Pr) radial to the hub by an angle (α) comprised between 0.1° and 45° and/or with respect to a plane transverse to the hub (Pt) by an angle (β) comprised between 0.1° and 45°.
  7. 7 . The wheel according to claim 6 , wherein each cable is inclined with respect to a plane (Pr) radial to the hub by an angle (α) of 10° and/or with respect to a plane (Pt) transverse to the hub by an angle (β) of 10°.
  8. 8 . The wheel according to claim 1 , wherein the external end of the cables is fixed on rods mounted against an external surface of the laminated strip.
  9. 9 . The wheel according to claim 1 , wherein the elastic member includes a plurality of leaf springs, and wherein the internal end of the cables is fixed to the hub by the plurality of leaf springs to modulate radial stiffness.
  10. 10 . The wheel according to claim 9 , wherein the leaf springs of the plurality of leaf springs are fixed at a level against an internal surface of the hub forming the abutment configured to limit deformation and extend longitudinally along a direction circumferential to the hub, each leaf spring of the plurality of leaf springs comprising two opposite longitudinal ends which are each connected to the internal end of a cable.
  11. 11 . The wheel according to claim 10 , wherein at least part of the plurality of leaf springs are fixed against the internal surface of the hub on an inner side of the wheel, and wherein at least part of plurality of leaf springs are fixed against the internal surface of the hub on an outer side of the wheel.
  12. 12 . The wheel according to claim 9 , wherein each leaf spring comprises a plurality of stainless steel leaves which are superimposed on each other.
  13. 13 . The wheel according to claim 9 , wherein the hub carries at least one disk protruding radially outwards and having an outer diameter against which an internal surface of the laminated strip is configured to come into abutment in order to limit deformation.
  14. 14 . The wheel according to claim 1 , wherein the internal end of the cables is fixed to the hub by U-bent leaves of the elastic member forming a spring to modulate the radial stiffness of the cables.
  15. 15 . The wheel according to claim 14 , wherein the U-bent leaves are fixed at respective free ends against an internal surface of the hub and extend longitudinally along an axial direction of the hub, each U-bent leaf being connected to the internal end of a cable.
  16. 16 . The wheel according to claim 15 , wherein at least part of the U-bent leaves extend longitudinally on an inner side of the wheel, and wherein at least part of the U-bent leaves extend longitudinally on an outer side of the wheel.
  17. 17 . The wheel according to claim 14 , wherein the hub carries at least one disk protruding radially outwards and having an inner diameter against which the U-bent leaves are configured to come into abutment in order to limit deformation, and an outer diameter against which an inner surface of the laminated strip is configured to come into abutment in order to limit deformation.

Description

BACKGROUND OF THE INVENTION The present invention relates to a deformable wheel with non-pneumatic load bearing. More particularly, the invention relates to a wheel which bears a load with its structural components and which has performance capacities suitable for equipping a vehicle intended to roll under extreme conditions such as those encountered on the Moon and on Mars. The pneumatic wheel has load bearing, road shock absorption and force transmission (accelerations, stops and changes of direction) capabilities that are particularly well suitable for many vehicles in particular bicycles, motorcycles, cars and trucks. The shock absorption capabilities of tires are also useful in other applications, for example for trolleys transporting medical equipment or sensitive electronic equipment. Alternatives to the pneumatic wheel exist. Mention may be made, for example, of solid tires and spring-loaded tires. However, these alternatives do not have the performance advantages of the pneumatic wheels. Particularly, the solid tires rely on the compression of the part in contact with the soil to bear the load. This type of tires can be heavy and rigid and does not have the capacity to absorb the shocks of the pneumatic wheels. When made more elastic, the conventional non-pneumatic wheels do not have the load bearing or the endurance of the pneumatic wheels. To overcome these drawbacks, the publication U.S. Pat. No. 7,418,988 proposes a tire with structural bearing which comprises an external annular strip and a plurality of spokes extending transversely and radially inwards from the annular strip to the hub of the wheel and intended to transmit in tension the load forces between the annular strip and the hub. The wheel with structural bearing according to this invention does not include a cavity intended to contain pressurized air and therefore does not need to have a seal with the rim of the wheel to maintain the internal air pressure. This wheel with structural bearing therefore does not require a tire in the usual sense. The spokes of this wheel act in tension to transmit the load forces between the wheel and the annular strip, which makes it possible in particular to bear the mass of a vehicle. The bearing forces are generated by the tension of the spokes which are not connected to the part of the annular strip in contact with the soil. The spokes also transmit the forces required for the acceleration, the stops and the turns. Whatever the alternatives known from the prior art for the production of non-pneumatic wheels, these generally do not give complete satisfaction, in particular when they are intended to roll under extreme conditions such as those encountered on the Moon and on Mars. Indeed, with such conditions, it is necessary for the wheel to be able to deform strongly when passing an obstacle while generating a contact pressure which is low and uniform to allow the vehicle to remain movable on loose soil such as soil found on the Moon and on Mars. SUMMARY OF THE INVENTION The main aim of the present invention is therefore to overcome such drawbacks by proposing a deformable wheel structure with non-pneumatic load bearing which can in particular equip vehicles intended to roll under extreme conditions such as those encountered on the moon and on Mars. In accordance with the invention, this aim is achieved thanks to a deformable wheel with non-pneumatic load bearing intended to equip a vehicle for rolling under extreme conditions such as those encountered on the moon and on Mars, comprising: a hub,a laminated annular strip intended to be in contact with the soil, positioned around the hub which is concentric therewith and comprising a plurality of concentric ferrules which are assembled with interposition of interposing layers each composed of a material whose Young's modulus is 600,000 to 1,000 times lower than that of the ferrules, anda plurality of metal cables whose outer diameter is comprised between 0.2 mm and 5 mm, each cable radially connecting the hub to the laminated strip while being fixed, on the one hand by an external end to the laminated strip, and on the other hand by an internal end to the hub by means of an elastic member making it possible to modulate the radial stiffness of the cables, each elastic member being associated with an abutment able to limit its deformation. The wheel according to the invention is remarkable in particular due to the presence of the laminated annular strip which comprises a plurality of concentric ferrules which are assembled with interposition of interposing layers each composed of a material whose Young's modulus is 600,000 to 1,000 times lower than that of the ferrules, for example made of elastomer material. Under an externally applied load, the part of the laminated strip in contact with the soil deforms, not in an essentially circular shape, but in a shape conforming to the surface of the soil while maintaining an essentially constant length of the fe