Deformable wheel with non-inflatable load-bearing and rotational stop disc for lunar and mars conditions

Abstract

The invention relates to a deformable wheel (2) with a non-inflatable load-bearing, intended for a vehicle equipped for driving in extreme environments such as on the moon and Mars, comprising: a hub (4) supporting at least one stop disc (20) projecting radially outwards; an annular tread layer (6) having an outer surface intended to be brought into contact with the ground and being deformable in the event of an externally applied load so as to match the ground surface, and an inner surface being able to abut against the stop disc so as to limit the deformation of the tread layer in the radial direction; and a plurality of radial reinforcements (8) connecting the tread layer to the hub, the stop disk being rotatably mounted on the hub such that the stop disk is rotatable when the inner surface of the tread layer abuts against the stop disk.

Description

Background Art

[0001] The present invention relates to a deformable wheel having non-pneumatic load bearing. More particularly, the present invention relates to a wheel that supports loads through its structural components and has performance capabilities suitable for equipping a vehicle intended for use in extreme environments such as those encountered on the Moon and Mars.

[0002] The weight-bearing, road-shock-absorbing, and force-transmitting (accelerating, stopping, and changing direction) capabilities of pneumatic wheels are particularly useful for many vehicles, especially bicycles, motorcycles, cars, and trucks. The shock-absorbing capabilities of pneumatic tires are also useful in other applications, such as carts for transporting medical equipment or sensitive electronic equipment.

[0003] There are alternatives to pneumatic wheels. These alternatives include solid tires and sprung tires. However, these alternatives do not have the performance advantages of pneumatic wheels. Specifically, solid tires rely on compression of the portion in contact with the ground to support the load. This type of tire can be heavy and rigid, and does not have the shock absorbing capabilities of pneumatic wheels. While they are made more resilient, conventional non-pneumatic wheels do not have the load support or durability of pneumatic wheels.

[0004] In order to overcome these drawbacks, document US 7,418,988 proposes a tire with structural support, which includes an outer annular strip and a plurality of spokes extending laterally and radially inwardly from the annular strip to the hub of the wheel and is intended to transfer load forces between the annular strip and the hub under tension.

[0005] The structurally supported wheel according to the present invention does not have a cavity intended to contain pressurized air and therefore does not need to have a seal with the rim of the wheel in order to maintain internal air pressure. Therefore, such a structurally supported wheel does not require a tire in the sense of the word.

[0006] The spokes of this wheel transmit the load forces between the wheel and the annular strip under tension, in particular allowing the mass of the vehicle to be supported. The supporting forces are generated by the tension of the spokes that are not connected to the portion of the annular strip that is in contact with the ground. The spokes also transmit the forces required for acceleration, stopping and turning.

[0007] Regardless of the known alternatives of the prior art for producing non-pneumatic wheels, these solutions are generally not completely satisfactory, especially when the non-pneumatic wheels are intended for rolling in extreme environments such as those encountered on the Moon and Mars. More specifically, in such environments, when negotiating obstacles, the wheel must be able to deform significantly while generating a low uniform contact pressure in order to enable the vehicle to maintain movement on soft ground such as that encountered on the Moon and Mars.

[0008] In patent application EP22192685 filed by the present applicant on August 29, 2022, a wheel is known that can meet these needs, in particular by the presence of a laminated annular strip comprising a plurality of concentric ferrules assembled by inserting an insert layer, each insert layer consisting of a material having a Young's modulus 600,000 to 1000 times less than that of the ferrule, for example made of an elastomeric material. Under externally applied loads, the portion of the laminated strip in contact with the ground deforms, but not substantially circularly, but in a shape matching the surface, while keeping the length of the ferrule substantially constant. The wheel according to this patent application can also generate a low and uniform contact pressure with the ground. In this way, a vehicle equipped with such a wheel can remain mobile (i.e., without sinking into the sand) even on soft ground (such as sand) as encountered on the moon and Mars.

[0009] The wheel described in this patent application also comprises solid discs of the hub which project radially outwards so as to form stops which can limit the movement of the tread layer of the wheel. More specifically, depending on the size of the obstacle to be traversed by the wheel, the inner surface of the laminated strip can come into abutment against these discs carried by the hub so as to limit the deformations to which the laminated strip is subjected.

[0010] Furthermore, depending on the use of the vehicle, it may be advantageous to be able to roll short distances at reduced speed when transporting a load so that the inner surface of the laminated strip can permanently abut against the disc carried by the hub even in the absence of obstacles.

[0011] However, in these cases, due to the significant difference in tangential speed between the tread layer and the stop disc, the tread layer can slip on the disc, which can damage the stopper and significantly change the inner surface of the tread layer. Therefore, the integrity of the wheel is threatened. Summary of the invention

[0012] The main object of the present invention is therefore to overcome such drawbacks by proposing a deformable wheel structure with non-pneumatic bearings comprising means to avoid any modification of the tread layer when it is in abutment therewith.

[0013] According to the invention, this object is achieved by a deformable wheel with non-pneumatic load-bearing, intended to be used to equip vehicles for driving in extreme environments such as those encountered on the moon and Mars, the deformable wheel comprising:

[0014] a hub supporting at least one stop disk protruding radially outward,

[0015] an annular tread layer positioned around the hub and having an outer surface intended for contact with the ground and capable of deforming in the event of an externally applied load so as to match the ground surface, and an inner surface capable of abutting against the stop disc so as to limit the deformation of the tread layer in the radial direction, and

[0016] a plurality of radial reinforcements connecting the tread layer to the hub,

[0017] And wherein, according to the present invention, the stop disc is rotatably mounted on the hub, so that when the inner surface of the tread layer abuts against the stop disc, the stop disc can rotate.

[0018] The wheel according to the invention is characterized in that the stop disc is rotatably mounted on the hub, which enables it to "roll" when the tread layer is in abutment against it, despite the difference in speed. The system thus represents a device of the ball bearing type, which is only active when the tread layer is in contact with the stop. Due to this rolling possibility of the stop disc, the risk of changes in the tread layer and therefore in the wheel is significantly reduced.

[0019] The stop disc is preferably mounted on the outer surface of the hub via a roller bearing.

[0020] In this case, the roller bearing may include a plurality of cylindrical rollers mounted between the outer surface of the hub and the inner annular strip of the retaining disc.

[0021] The retaining disc may include an outer annular band mounted around an inner band by a plurality of spring joints.

[0022] In this case, the spring joints can each be formed by a deformable ring.

[0023] The deformable ring of the spring joint is advantageously constituted by coils of stainless steel strip.

[0024] Preferably, each spring joint also comprises a bushing forming a rigid stop mounted inside the ring.

[0025] The cylindrical rollers are advantageously regularly distributed around the axis of rotation of the wheel on the outer surface of the hub.

[0026] Preferably, the outer strip of the stop disc is covered with an outer protector made of leather.

[0027] The wheel hub may support two stop disks spaced apart from one another along the axis of rotation of the wheel.

[0028] The tread layer may be a metal shear strip comprising a metal core provided with corrugations sandwiched between a collar and a plurality of circumferential springs which impart to the tread layer the ability to deform when bent. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Other features and advantages of the invention will become apparent from the following description given with reference to the accompanying drawings which illustrate non-limiting exemplary embodiments. In the drawings:

[0030] Figure 1 is a schematic front view of a wheel according to an embodiment of the present invention;

[0031] Figure 2 yes Figure 1 a perspective cross-sectional view of a wheel of; and

[0032] Figure 3 yes Figure 1 Cross-sectional view of a wheel. DETAILED DESCRIPTION

[0033] The present invention relates to a Figure 1 The illustrated deformable wheels have non-pneumatic load bearings suitable for equipping vehicles intended for use in extreme environments such as those encountered on the Moon and Mars.

[0034] Figure 1 The wheel 2 shown in the figure mainly comprises a hub 4; an annular tread layer 6, which has an outer surface intended for contact with the ground and can be deformed under externally applied loads so as to match the surface; and a plurality of radial reinforcements (here metal cables 8) which radially connect the hub to the tread layer.

[0035] In this embodiment, the tread layer 6 is a flexible strip comprising a metal core 10 provided with a plurality of corrugations 12 sandwiched between a collar 14 and a plurality of circumferential springs 16 which give it the ability to deform in bending.

[0036] More precisely, if Figure 2 and Figure 3 As shown, the corrugations 12 of the core 10 of the tread layer are formed by metal sheets folded in a V-shape in the longitudinal direction (in other words parallel to the longitudinal axis of rotation XX of the wheel 2 ).

[0037] It should be noted that the tip of the V-shape of the metal sheet forming the corrugation 12 points towards the inside of the wheel (in other words towards the axis of rotation XX thereof) and opens outwards towards the outside of the wheel.

[0038] It should also be noted that each relevant portion 12 of the core of the tread layer is symmetrical relative to a plane P radial to the wheel (and passing through the tip of the V-shape of the corrugation).

[0039] It should also be noted that the metal sheet forming the corrugation advantageously has holes 18 distributed over its entire length in order to reduce the weight of the wheel.

[0040] The collar 14 of the tread layer 6 of the wheel according to this embodiment is made of metal or a composite material (for example, with glass fibers or carbon fibers).

[0041] Finally, the tread layer 6 of the wheel according to this embodiment comprises a plurality of circumferential springs 16 which give it the ability to deform when bending.

[0042] As indicated previously, in this embodiment, the radial reinforcements which radially connect the hub 4 of the wheel to the tread layer 6 consist of metal cables 8 .

[0043] It should also be noted that the radial reinforcements connecting the hub 4 of the wheel radially to the tread layer 6 may consist of springs (this embodiment is not shown in the figures) instead of metal cables.

[0044] Similarly, in another embodiment (not shown in the figures), the tread layer is a laminated annular strip comprising a plurality of concentric rings assembled by inserting interleafs, each insert being composed of a material having a Young's modulus 600,000 to 1000 times less than that of the rings.

[0045] The ferrule of such a laminated strip may be made of metal or composite material, while the interposer may be composed of a superelastic elastomer having a glass transition temperature below 120°C.

[0046] Reference may be made to patent application EP22192685 filed by the present applicant on August 29, 2022, which describes such a wheel architecture with a laminated tread layer.

[0047] Whatever the embodiment, the wheel hub 4 of the wheel carries at least one stop disk 20 which projects radially toward the outside of the wheel.

[0048] When there is a significant obstacle (e.g., a rock) on the surface on which the wheel 2 rolls, the portion of the tread layer 6 in contact with the ground deforms to match the contour of the obstacle. In this case, depending on the size of the obstacle, the inner surface of the tread layer may abut against the outer diameter of the stop disc 20 carried by the hub 4 in order to limit the deformation to which the tread layer is subjected. Similar situations may also occur during slow rolling and under severe overloads.

[0049] According to the invention, the stop disc 20 is rotatably mounted on the hub 4 so that it can rotate about the axis XX of the wheel when the inner surface of the tread layer 6 abuts against it.

[0050] More precisely, in Figures 1 to 3 In the embodiment, the retaining plate 20 is mounted on the outer surface of the hub 4 through a roller bearing 22.

[0051] This roller bearing 22 preferably comprises a plurality of cylindrical rollers 24 mounted between the outer surface of the hub 4 and an inner annular strip 26 of the stop disc. The cylindrical rollers 24 are regularly distributed around the entire axis of rotation XX of the wheel.

[0052] In this way, when the inner surface of the tread layer 6 abuts the outer diameter of the stop disc 20 (especially when the wheel rolls over a significant obstacle), the wheel can still roll around the hub despite the different rotational speeds of the hub and the tread layer.

[0053] According to an advantageous arrangement, the stop disk 20 also comprises an outer annular strip 28 which is mounted around the inner strip 26 by means of a plurality of spring joints 30 .

[0054] exist Figures 1 to 3 In the embodiment of the invention, the spring joints are each formed by a deformable ring 30, which is advantageously formed by a plurality of turns of a stainless steel strip (e.g. twelve turns of a strip with a thickness of 0.15 mm). Alternatively, these rings may be made of a composite material of the glass fiber and resin type.

[0055] It should be noted that the deformable rings 30 are preferably regularly distributed around the entire axis of rotation XX of the wheel.

[0056] According to another advantageous arrangement, each spring joint also comprises a bushing 32 forming a rigid stop mounted inside the ring 30 .

[0057] This bushing 32 can be fixed on the inner strip side 26 of the stop disc or on the outer strip side 28 of the stop disc. In the event of strong deformation of the tread layer, this bushing prevents the deformable ring 30 from deforming too much.

[0058] According to a further advantageous arrangement, the outer strip 28 of the stop disc is covered with an outer protective piece 34 , for example made of leather.

[0059] In another embodiment not shown, the wheel hub of the wheel carries two stop disks spaced apart from one another along the axis of rotation XX of the wheel.

Claims

1. A deformable wheel (2) with non-pneumatic load-bearing, the deformable wheel being intended for use in equipping a vehicle for traveling in extreme environments such as those encountered on the moon and Mars, the deformable wheel (2) comprising: a wheel hub (4), the wheel hub (4) supporting at least one stop disk (20) protruding radially outwards, an annular tread layer (6) positioned around the hub and having an outer surface and an inner surface, the outer surface being intended for contact with the ground and being deformable in the event of an externally applied load so as to match the ground surface, and the inner surface being able to abut against the stop disc so as to limit the deformation of the tread layer in the radial direction, and a plurality of radial reinforcements (8) connecting the tread layer to the hub, The deformable wheel is characterized in that the stop disc (20) is rotatably mounted on the wheel hub so that the stop disc can rotate when the inner surface of the tread layer abuts against the stop disc.

2. The wheel according to claim 1, wherein the retaining plate (20) is mounted on the outer surface of the hub (4) via a roller bearing (22).

3. The wheel of claim 2, wherein the roller bearing (22) comprises a plurality of cylindrical rollers (24) mounted between the outer surface of the hub and an inner annular strip (26) of the retaining disc (20).

4. Wheel according to claim 3, wherein the stop disc (20) comprises an outer annular strip (28) mounted around the inner strip (26) by means of a plurality of spring joints (30).

5. Wheel according to claim 4, wherein the spring joints are each formed by a deformable ring (30).

6. Wheel according to claim 5, wherein the deformable ring (30) of the spring joint is constituted by a winding of a stainless steel strip.

7. Wheel according to one of claims 5 and 6, wherein each spring joint also comprises a bushing (32) forming a rigid stop mounted inside the ring (30).

8. A wheel according to any one of claims 3 to 7, wherein the cylindrical rollers (24) are regularly distributed on the outer surface of the hub (4) around the axis of rotation (XX) of the wheel.

9. Wheel according to any one of claims 3 to 8, wherein the outer strip (28) of the stop disc (20) is covered with an outer protector (34) made of leather.

10. Wheel according to any one of claims 1 to 9, wherein the wheel hub (4) supports two stop discs spaced apart from one another along the axis of rotation (XX) of the wheel.

11. A wheel according to any one of claims 1 to 10, wherein the tread layer (6) is a metal shear strip comprising a metal core (10) provided with a corrugated member (12) sandwiched between a collar (14) and a plurality of circumferential springs (16) which give the tread layer the ability to deform when bent.

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