Abstract
The present invention is directed to a non-pneumatic tire comprising a hub portion and a ring member arranged essentially concentrically about the hub portion, wherein the ring member comprises a tread portion on its radially outer side. Moreover, the tire comprises a sidewall connecting the hub portion with the ring member, wherein the sidewall comprises multiple sidewall members, each sidewall member being connected on a first side to the hub portion and on a second side to the ring member. Adjacent sidewall members overlap at least partially in a manner whereby they can move relatively to each other under tire loading conditions, such as when the tire is mounted on a vehicle.
Claims
1. A non-pneumatic tire comprising: a hub portion; a ring member arranged essentially concentrically about the hub portion, the ring member comprising a tread portion on its radially outer side; a sidewall connecting the hub portion with the ring member, wherein the sidewall comprises multiple sidewall members, each sidewall member being connected on a first side to the hub portion and on a second side to the ring member, wherein adjacent sidewall members at least partially overlap in a manner whereby they can move relatively to each other under the condition of being loaded.
2. The non-pneumatic tire of claim 1, wherein the sidewall members are plate-like members, and wherein each plate-like member is attached at a first face side to a radially outer side of the hub portion and at a second face side to a radially inner side of the ring portion.
3. The non-pneumatic tire of claim 1, wherein the sidewall members cover a lateral side of the tire.
4. The non-pneumatic tire of claim 1, wherein adjacent sidewall members are at least partially offset in an axial direction.
5. The non-pneumatic tire of claim 1, wherein from 6 to 60 sidewall members are arranged circumferentially around the tire.
6. The non-pneumatic tire of claim 1, wherein one or more of the sidewall members are essentially sickle shaped.
7. The non-pneumatic tire of claim 1, wherein each sickle-shaped sidewall member is attached to the hub portion at a first circumferential position and attached to the ring member at a second circumferential position, wherein the first circumferential position and the second circumferential position are shifted relatively to each other by at least 10°, measured in the circumferential direction about an axis of rotation of the tire.
8. The non-pneumatic tire of claim 1, wherein the first circumferential position and the second circumferential position are shifted by 20° to 150°.
9. The non-pneumatic tire of claim 2, wherein the first face side is attached to the hub portion at an angle within a range of 1° to 45° with respect to an equatorial plane of the tire.
10. The non-pneumatic tire of claim 2, wherein the second face side is attached to the ring portion at an angle within a range of 1° to 45° with respect to an equatorial plane of the tire.
11. The non-pneumatic tire of claim 2, wherein two adjacent plate-like elements at least partially overlap along their extension from the hub portion to the ring member.
12. The non-pneumatic tire of claim 2, wherein the first face side extends over a length of 2% to 20% of the radially outer circumference of the hub portion.
13. The non-pneumatic tire of claim 2, wherein the second face side extends over a length of 2% to 20% of the radially inner circumference of the ring member.
14. The non-pneumatic tire of claim 1, wherein the sidewall members overlap in a non-loaded state by at least 2 mm over at least 50% of their length of extension from the hub portion to the ring member.
15. The non-pneumatic tire of claim 1, wherein said sidewall members are comprised of at least one polymeric material selected from the group consisting of rubber formulations, thermoplastic elastomers, plasticized thermoplastics, and polyurethanes.
16. The non-pneumatic tire of claim 1, wherein the tire has two opposite lateral sides, and wherein the tire has only one sidewall.
17. The non-pneumatic tire of claim 1, wherein a lateral side of the tire between hub portion and ring member, which is opposite to said sidewall, has at least one aperture or is left open.
18. The non-pneumatic tire of claim 1, wherein the sidewall members resiliently support the ring member on the hub portion.
19. The non-pneumatic tire of claim 1, further comprising spokes resiliently supporting the ring member on the hub portion.
20. The non-pneumatic tire of claim 19, wherein said spokes are arranged axially inside of the sidewall members.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] The structure, operation, and advantages of the invention will become more apparent upon contemplation of the following description taken in conjunction with the accompanying drawings, wherein
[0048] FIG. 1 is a schematic side view of a tire in accordance with a first embodiment of the invention.
[0049] FIG. 2a is a schematic partial cross section looking along the radial direction onto a radially outer side of the hub portion with attached sidewall members.
[0050] FIG. 2b is a schematic partial cross section looking along the radial direction onto a radially outer side of a hub portion with attached sidewall members according to an alternative embodiment of the invention.
[0051] FIG. 3 is a schematic perspective view of an exemplary spoke structure in accordance with an embodiment of the present invention, whereas the sidewalls and the tread portions are not shown for the sake of clarity.
[0052] FIG. 4 is a schematic sideview of the spoke structure already shown in FIG. 3.
DETAILED DESCRIPTION OF THE INVENTION
[0053] FIG. 1 shows an embodiment of a non-pneumatic tire 1 comprising a central hub or hub portion 2, a shear band or ring member 3 carrying a tread portion 5, wherein the hub portion 2 and the ring member 3 are connected by a sidewall 7 comprising a plurality of plate-shaped sidewall members 6. The sidewall members 6 have in this non-limiting embodiment a sickle-shape, wherein each sidewall member 6 is connected at one end to the central hub portion 2 and at the opposite end to the ring member 3. This sidewall structure is preferably provided only on one lateral side of the tire 1 but may also be provided on both lateral sides of the tire 1. Upon loading the tire 1, e.g. when the tire 1 is mounted to a vehicle, the tire 1 will deform and the sickle-shaped sidewall members 6 can slide relative to each other so as to keep the space between the hub portion 2 and the ring member 3 laterally covered. In particular, it may be avoided by such means that dirt and stones enter the space between the hub portion 2 and the ring member 3. Considerable bulging of the sidewall 7 can be avoided. The sickle-shaped members 6 extend from a first angular position at which they are connected to the hub portion 2 to a second (different) angular position at the ring member 3. This has been illustrated for one sidewall member by the angle (3 in FIG. 1, which is as shown in the drawing on the order of 120°. The angle (3 is measured in a plane perpendicular to the axial direction a of the tire 1. The indicated radial direction r is also perpendicular to the axial direction a. The circumferential direction c is parallel to the circumference of the tire 1 and parallel to the equatorial plane of the tire (not shown in FIG. 1).
[0054] FIG. 2a is a partial cross-section through some sidewall members 6 viewed along the radial direction r. The sidewall members 6 overlap essentially in a circumferential direction c so that when viewed in the axial direction there is no slot left between adjacent sidewall members 6. In other words, neighboring sidewall members are at least partially axially offset with respect to each other. Moreover, in order to allow a sliding motion in a direction s, which is almost in parallel to the circumferential direction c, the sidewall members have a non-zero angle α with the circumferential direction c. Said angle α is within a range of 5° to 10°. In particular, trailing edges of adjacent sidewall members 6, or preferably of all sidewall members 6, are arranged at the same axial position along the circumference of the hub portion 2. The same applies to the leading edges of the sidewall members 6 which are arranged at the same axial position along the circumferential direction, wherein the axial position of the leading edges is different than the axial position of the trailing edges, in other words said position are axially offset. Similarly to the attachment and/or arrangement of the sidewall members 6 at the hub portion 2, the sidewall members 6 are also attached to the radially inner side of the ring member 3. The sidewall members 6 may join the radially inner side or surface of the ring member 3 at the same or similar angles as suggested herein for the attachment of the sidewall members 6 to the hub portion 2.
[0055] FIG. 2b shows an alternative embodiment in accordance with the invention with respect to the embodiment already described in the context of FIG. 2a. According to FIG. 2b, adjacent sidewall members 6′ attached to a hub portion 2′ can slide relatively to each other along the circumferential direction c. The preferred direction of motion has been further indicated by the sliding direction s′ which is in parallel with the circumferential direction c. In other words, adjacent sidewall members 6′ are axially offset and (partially) overlap in a circumferential direction. Thus, when viewed in the axial direction the sidewall fully covers the interior of the tire. In accordance with the embodiment shown in FIG. 2b, it is preferred that the axial positions of the sidewall elements 6′ alternate between a first and a second axial position such that a first sidewall member 6′ is axially offset with regard to the position of a circumferentially adjacent second sidewall member 6′ and that a third sidewall member 6′ adjacent the second sidewall member 6′ has again essentially the same axial position as the first sidewall member 6. In other words, each second sidewall member 6′ (in the circumferential direction) is axially offset with respect to the remaining sidewall members. In such an embodiment, the number of sidewall members 6′ is preferably even.
[0056] When making reference herein to axial, radial or circumferential directions (a, r, c), these terms shall be understood as commonly understood in the tire art. In particular, a reference to an axial direction means a direction in parallel to the axis of rotation of the tire. A reference to the circumferential direction is a direction concentric about the axis of rotation of the tire and/or in parallel to an equatorial plane of the tire. The radial direction is perpendicular to the axis of rotation of the tire. The equatorial plane of the tire is also a term which is known to the person skilled in the tire art. In particular it is perpendicular to the axis of rotation of the tire and separates the tire into two equal parts (each of which constitute one-half of the tire).
[0057] Axially or laterally behind the sidewall 7 comprising the sidewall members 6, the tire 1 may comprise a plurality of spokes or a spoke structure (not shown in FIGS. 1 and 2) resiliently supporting the ring member 3 on the hub portion 2.
[0058] FIGS. 3 and 4 show a non-limiting embodiment of such spokes 4, which are preferably made of carbon fiber-based material and are arranged in twelve pairs of groups about the circumference of the tire 1. The spokes 4 extend in general from the radially outer surface of the hub portion 2 to the radially inner surface of the ring member 3. Each pair of groups consists of a first group of spokes 4 extending from a line adjacent and along a first axially outer edge of the ring member 3 towards the hub portion 2, wherein the spokes 4 cross beside each other adjacent a crossing point 12 between the hub portion 2 and the ring member 3 and further extend towards and onto the hub or hub portion 2. As shown in FIG. 3, the spokes 4 connect to the hub portion 2 at axial positions which are closer to the axial center of the hub portion 2 than the axial positions at which the spokes 4 of the first group are attached to the ring member 3. The second group of spokes 4 of the same pair (each group of the pair being essentially arranged at the same circumferential position or angle) extends from a line adjacent and along a second axially outer edge of the ring member 3 (axially opposite to said first edge) towards the hub portion 2. The spokes 4 of the second group cross beside each other adjacent a common crossing point between the hub portion 2 and the ring member 3 and further extend towards and onto the hub portion 2. Again the spokes 4 connect to the hub at axial positions which are closer to the axial center of the hub portion 2 than the axial position at which the spokes 4 of the second group are attached to the ring member 3. Such an arrangement may improve the stiffness of the tire 1 with regard to lateral forces. Moreover, as shown in FIG. 3, the spokes 4 of a group (sharing a common crossing point 12) are preferably attached to the hub portion 2 along a non-straight line extending in the axial and circumferential directions. Such an arrangement improves stability with regard to lateral forces further. Preferably, the crossing points 12 of all pairs have a radial distance to the radially outer surface of the hub portion 2 which is less than 50% (even more preferably between 45% and 25%) of the radial distance between the radially outer side of the hub portion 2 and the radially inner side of the ring member 3.
[0059] While the spokes have been shown in accordance with FIGS. 3 and 4 as rod-like elements, such spokes may for instance have plate-like shapes and/or a lattice-like or grid-like structure. Thus, in an embodiment of the invention, the resilient supporting structure arranged between the hub portion 2 and the ring member 3 can be provided as known in the existing art of non-pneumatic tires. In an example, the ring member could be circumferentially supported on the hub portion 2 by a resilient supporting structure extending about the hub portion 2 to support the ring member 3 on the hub portion 2.
[0060] In general, hub portion 2, spokes 4, sidewall members 6 and the shear band or ring member 3 may comprise a polymer material or composition.
[0061] While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention.
