Self-supporting spoke structure for non-pneumatic tires

Abstract

A non-pneumatic tire includes a lower ring having a first diameter and an upper ring having a second diameter. The upper ring is substantially coaxial with the lower ring. A support structure connects the lower ring to the upper ring. The support structure is composed of a plurality of spokes. The support structure is arranged and configured such that adjacent spokes among the plurality of spokes contact each other when a high-impact event occurs.

Description

Technical Field

[0001] The present disclosure relates to non-pneumatic tires. More particularly, the present disclosure relates to non-pneumatic tires having a support structure with spokes designed to contact each other upon the occurrence of a high-impact event.

Background Art

[0002] Various tire structures have been developed that enable a tire to travel in a non-inflated or under-inflated state. Non-pneumatic tires do not require inflation, while "run-flat tires" can continue to operate relatively fast for an extended period even after a puncture and partial or complete deflation. Non-pneumatic tires may include a support structure such as spokes or webbing that connect a lower ring to an upper ring. In some non-pneumatic tires, a circumferential tread may be attached to the upper ring of the tire.

[0003] The circumferential tread may include a tread band. The tread band may be a single layer or multi-layer band of material. Such a tread band may also be referred to as a shear band, shear element, or thin annular high-strength band element. When used in a non-pneumatic tire or a pneumatic tire in a partially pressurized or non-pressurized state, the shear element acts as a structural compression member. When used in a fully pressurized pneumatic tire, the shear element acts as a tension member.

[0004] Tire design involves balancing many factors including, but not limited to, load capacity, handling, and ride comfort, for both pneumatic and non-pneumatic tires. Regardless of the balance chosen among these factors, non-pneumatic tires must be durable and able to withstand high-impact events such as collisions with curbs, potholes, or other obstacles or road defects.

Summary of the Invention

[0005] In one embodiment, a non-pneumatic tire includes a lower ring having a first diameter and an upper ring having a second diameter. The upper ring is substantially coaxial with the lower ring. A support structure connects the lower ring to the upper ring. The support structure is composed of a plurality of spokes. The plurality of spokes are arranged in at least a first group of spokes and a second group of spokes axially spaced from the first group of spokes. Each of the plurality of spokes includes a first end connected to the lower ring and a second end connected to the upper ring. A knee portion is located between the first end and the second end. The knee portion is curved concave with respect to the lower ring.

[0006] In another embodiment, a method of manufacturing a non-pneumatic tire includes providing a lower ring having a first diameter and an upper ring having a second diameter larger than the first diameter. A plurality of spokes are formed. Each spoke extends between a first end and a second end. Each spoke has a knee portion located between the first end and the second end. The plurality of spokes are arranged in a first group of spokes and a second group of spokes axially spaced from the first group of spokes. The lower ring is connected to the upper ring using the first group of spokes and the second group of spokes.

[0007] In yet another embodiment, a non-pneumatic tire includes a lower ring having a first diameter and an upper ring having a second diameter. The upper ring is substantially coaxial with the lower ring. A support structure connects the lower ring to the upper ring. The support structure is composed of a plurality of spokes. The support structure is arranged and configured such that adjacent spokes among the plurality of spokes do not contact each other when the non-pneumatic tire is in a first state, and adjacent spokes among the plurality of spokes contact each other when the non-pneumatic tire is in a second state. The first state is when the tire is rolling on a flat surface. The second state is different from the first state.

Brief Description of the Drawings

[0008] In the accompanying drawings, structures that illustrate exemplary embodiments of the claimed invention are illustrated along with the detailed description provided below. Like elements are identified with the same reference numerals. It should be understood that an element shown as a single component may be replaced by a number of components, and an element shown as a number of components may be replaced by a single component. The drawings are not to scale, and the ratios of certain elements may be exaggerated for illustration purposes.

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[0009] The following includes definitions of selected terms used in this specification. The definitions include the scope of the terms and various examples or forms of components that can be used for implementation. The examples are not intended to be limiting. Both the singular and plural forms of the terms can be within the scope of the definition.

[0010] "Axial" and "axially" refer to a direction parallel to the axis of rotation of the tire.

[0011] "Circumferential" and "circumferentially" refer to a direction extending along the outer circumference of the surface of the tread that is perpendicular to the axial direction.

[0012] "Radial" and "radially" refer to a direction perpendicular to the axis of rotation of the tire.

[0013] As used herein, "tread" refers to the portion of the tire that contacts the road or ground at normal inflation and normal load.

[0014] Although common tire components are described by similar terms used in the following description, of course, since the terms have slightly different implications, those skilled in the art should understand that none of the following terms are purely interchangeable with other terms used to describe common tire components.

[0015] In this specification, directions are described with reference to the axis of rotation of the tire. The terms "upward" and "upwardly" refer to the general direction towards the tread of the tire, and "downward" and "downwardly" refer to the general direction towards the axis of rotation of the tire. Thus, when relative directional terms such as "upper" and "lower" or "top" and "bottom" are used in relation to an element, the "upper" or "top" element is spaced closer to the tread than the "lower" or "bottom" element. Additionally, when relative directional terms such as "above" or "below" are used in relation to an element, an element "above" another element is closer to the tread than the other element.

[0016] The terms "inner" and "inwardly" refer to the general direction towards the equatorial plane of the tire, and "outer" and "outwardly" refer to the general direction away from the equatorial plane of the tire and towards the sidewall of the tire. Thus, when relative directional terms such as "inner" and "outer" are used in relation to an element, the "inner" element is spaced closer to the equatorial plane of the tire than the "outer" element.

[0017] Figures 1 - 5 illustrate one embodiment of the non - pneumatic tire 10. The non - pneumatic tire 10 is merely an exemplary figure and is not intended to be limiting. In the illustrated embodiment, the non - pneumatic tire 10 includes a generally annular lower ring 20. The lower ring 20 can engage a vehicle hub (not shown) for attaching the tire 10 to a vehicle. The lower ring 20 has an inner surface 23 and an outer surface 24 and can be made from a polymer material, an elastomeric material, a metal, a composite material composed of a polymer reinforced with glass fibers or carbon fibers, or any other desired material or combination of materials.

[0018] The non-pneumatic tire 10 further includes a substantially annular upper ring 30. The upper ring 30 has a diameter larger than that of the lower ring 20 and is substantially coaxial with the lower ring 20. The upper ring 30 has an inner surface 33 and an outer surface 34 and can be made of a polymer material, an elastomeric material, a metal, a composite material composed of a polymer reinforced with glass or carbon fibers, or any other desired material or combination of materials. The circumferential tread 70 is attached to the outer surface 34 of the upper ring 30. The circumferential tread 70 can be attached to the upper ring 30 with an adhesive, mechanically, or in any other desired configuration.

[0019] As shown in FIG. 3, the circumferential tread 70 includes a tread band 72 and a tread layer 74. The tread band 72 and the tread layer 74 may be made of the same material or different materials. The tread layer 74 may be made of rubber and may include tread elements (not shown) such as grooves, ribs, blocks, lugs, sipes, studs, or any other desired elements. The tread band may include a filament assembly.

[0020] In the illustrated embodiment, the tread band 72 is shown as a single layer. In an alternative embodiment, the tread band may be a multi-layer band. Such a multi-layer tread band can include one or more layers of substantially non-extensible materials. Those layers may be formed from a sheet of material, a cord of material, a filament of material, or any other desired configuration. In other alternative embodiments, the multi-layer tread band can include a layer of extensible material such as an elastomer. According to an exemplary embodiment, the tread band can include a pair of non-extensible layers separated by a layer of extensible material. In yet other alternative embodiments, the tread band may include a shear band, a shear element, or a band referred to as a thin annular high-strength band element.

[0021] The support structure 100 connects the lower ring 20 to the upper ring 30. The support structure 100 extends from the outer surface 24 of the lower ring 20 and the inner surface 33 of the upper ring 30. The support structure 100 is composed of a plurality of spokes 200. In the illustrated embodiment, the plurality of spokes 200 are arranged in two axially spaced-apart spoke groups, including a first spoke group 202 and a second spoke group 204 axially spaced from the first spoke group 202. In an alternative embodiment, the support structure can include three or more axially spaced-apart spoke groups.

[0022] As shown in FIG. 3, the first spoke group 202 and the second spoke group 204 are axially spaced from each other. In an alternative embodiment, the distance between the first spoke group and the second spoke group can be greater, smaller, or the first and second spoke groups can be arranged without a gap therebetween. When viewed from the perspective shown in FIG. 1, each spoke 200 of the first spoke group 202 is substantially convex with respect to the clockwise circumferential direction of the non-pneumatic tire 10, and each spoke of the second spoke group 204 is substantially concave with respect to the clockwise circumferential direction of the non-pneumatic tire 10.

[0023] All the spokes 200 of the first and second spoke groups 202, 204 have the same configuration. Therefore, the description of the spoke 200 is made with reference to the single spoke 200 shown in FIG. 6. The spoke 200 may be manufactured from a metal such as steel or aluminum, a polymer such as polyester or nylon, a composite material such as glass fiber or carbon fiber reinforced polymer, or any other desired material or combination of materials. The spoke 200 may be provided with a reinforcing material (not shown).

[0024] The spoke 200 extends between a first end 206 and a second end 208 and has a substantially rectangular cross-section including a first surface 210 and a second surface 212 facing the first surface 210. The spoke thickness t refers to the distance between the first surface 210 and the second surface 212. In the illustrated embodiment, the spoke 200 has a constant thickness between the first end 206 and the second end 208. In an alternative embodiment, the thickness of the spoke may vary between the first end and the second end. For example, the spoke may have relatively thick portions at the first and second ends and a relatively thin portion therebetween. In other alternative embodiments, the spoke may have any desired cross-sectional shape (e.g., circular, diamond-shaped, hexagonal, etc.) or a combination of different cross-sectional shapes.

[0025] Towards the first end 206 of the spoke 200, an integral foot portion 214 is provided. The first surface 210 of the spoke 200 at the foot portion 214 is attached to the outer surface 24 of the lower ring 20 in order to connect the first end 206 of the spoke 200 to the lower ring 20. The foot portion 214 may be attached to the outer surface 24 of the lower ring 20 using welding, brazing, soldering, adhesives, mechanical fasteners (e.g., bolts, rivets), key / keyway, or any other desired configuration. In the illustrated embodiment, the foot portion 214 is substantially linear, and the overall length (the dimension of the foot portion extending along the circumferential direction of the tire) and the overall width (the dimension of the foot portion extending along the axial direction of the tire) are fixed to the outer surface 24 of the lower ring 20. In an alternative embodiment, the foot portion may be a separate component attached to the spoke. In other alternative embodiments, the foot portion may be curved to match the radius of curvature of the outer surface of the lower ring or may have any other desired curvature. In yet other alternative embodiments, only a portion of the foot portion or multiple separate portions may be attached to the outer surface of the lower ring. In yet other alternative embodiments, the foot portion may be attached under the outer surface of the lower ring, or the spoke may extend through the lower ring such that the foot portion can be attached to the inner surface of the lower ring.

[0026] A flexure member 216 is provided at the second end 208 of the spoke 200. The flexure member 216 has a width extending along the axial direction of the tire. The flexure member 216 may be manufactured from a polymer (e.g., urethane or rubber), a thin curved metal piece, or any other desired material or combination of materials. In the illustrated embodiment, the flexure member 216 is provided as a rectangular parallelepiped and is arranged such that the ends of the flexure member 216 are aligned with the second end 208 of the spoke 200. In other alternative embodiments, the flexure member may be arranged such that the ends of the flexure member are recessed from the second end of the spoke, or the ends of the flexure member may extend beyond the second end of the spoke. In still other alternative embodiments, the flexure member may be replaced with a mechanical pin joint (i.e., hinge).

[0027] The flexure member 216 includes a spoke-facing surface 218 and a ring-facing surface 220. The spoke-facing surface 218 of the flexure member 216 is attached to the second surface 212 of the spoke 200, and the ring-facing surface 220 is attached to the inner surface 33 of the upper ring 30 to connect the second end 208 of the spoke 200 to the upper ring 30. The attachment between the flexure member 216 and the spoke 200, or between the flexure member 216 and the upper ring 30, can be achieved using welding, brazing, soldering, adhesives, mechanical fasteners (e.g., bolts, rivets), key / keyway, or any other desired configuration. For example, the attachment can be made by directly casting urethane onto the spoke, whether or not the spoke is initially coated with a primer.

[0028] The flexure member 216 provides flexibility to the connection between the second end 208 of the spoke 200 and the upper ring 30. This flexibility reduces the possibility of high stress occurring within the spoke 200, thereby improving the robustness of the non-pneumatic tire 10. Compared with the flexible connection provided by the flexure member 216, the connection provided by the foot portion 214 at the first end 206 of the spoke 200 is more rigid.

[0029] In an alternative embodiment, the flexure member may have a shape or configuration different from that specifically illustrated and described. In other alternative embodiments, additional structure(s) and / or mechanism(s) can supplement the flexure member for attaching the second end of the spoke to the upper ring. In still other alternative embodiments, the flexure member may be omitted and the second end of the spoke may be attached directly to the upper ring. In these alternative embodiments, the second end of the spoke may be attached directly on the inner surface of the upper ring on the inner surface of the upper ring, or the spoke may extend through the upper ring such that the second end can be attached to the outer surface of the upper ring.

[0030] The spoke 200 includes a knee portion 222 between the first end 206 and the second end 208. The knee portion 222 has a first radius of curvature r 1 . According to an exemplary embodiment, the first radius of curvature r 1 is 2 to 6 inches (5 to 15 cm). When attached to the upper ring and the lower rings 20, 30, the knee portion 222 is curved concave with respect to the lower ring 20.

[0031] A transition portion 224 is provided between the knee portion 222 and the first end 206. The transition portion 224 has a second radius of curvature r 2 . According to an exemplary embodiment, the second radius of curvature r 2 is 0 to 2 inches (0 to 5 cm). When attached to the upper ring and the lower rings 20, 30, the transition portion 224 is curved convex with respect to the lower ring 20. Thus, for a single spoke 200, the knee portion 222 and the transition portion 224 are curved concave in opposite directions. In alternative embodiments, the knee portion and the transition portion are curved concave (or convex) in the same direction.

[0032] The foot portion 214 extends from the transition portion 224 to the first end 206 of the spoke 200. The first connection portion 226 connects the transition portion 224 to the knee portion 222, and the second connection portion 228 connects the knee portion 222 to the second end 208 of the spoke 200. In the illustrated embodiment, both the first and second connection portions 226, 228 are linear. In alternative embodiments, the first connection portion or the second connection portion may be curved or may have any other desired configuration. In other alternative embodiments, the transition portion and the foot portion may be omitted. In such alternative embodiments, the first end of the spoke is disposed at the end of the first connection portion.

[0033] Base plane p 1 intersects the transition portion 224 and the second end 208 of the spoke 200 and functions as a reference for aspects regarding various dimensions of the spoke 200. The base plane p 1 and a second plane p that extends tangentially to the outer surface 24 of the lower ring 20 at the transition portion 224 2 The angle between them is α. According to an exemplary embodiment, the angle α is +0 to 20 degrees. The base plane p 1 The distance between the transition portion 224 and the second end 208 of the spoke 200 along a direction parallel to the base plane p is d 1 According to an exemplary embodiment, the distance d 1 is 10 to 25 inches (25 to 63.5 cm). The base plane p 1 The distance between the center of the transition portion 224 and the center of the first curvature r of the knee portion 222 along a direction parallel to the base plane p 1 is d 2 According to an exemplary embodiment, the value of the distance d 2 is 20 to 70 percent of the distance d 1 The base plane p 1 The maximum distance between the knee portion 222 and the base plane p along a direction perpendicular to the base plane p 1 is d 3 According to an exemplary embodiment, the distance d 3 is 2 to 4 inches (5 to 10 cm).

[0034] Referring to FIG. 10, the transition portion 224 of one spoke 200 is separated from the first end 206 of the adjacent spoke 200 by a first spacing distance s 1 only. The second end 208 of the adjacent spoke 200 is separated from each other by a second spacing distance s 2 only (see also FIG. 5).

[0035] A non-pneumatic tire configured according to the above design parameters can provide a more robust assembly, especially with respect to shock performance. FIGS. 7 and 8 show the tire in an exemplary first state. As shown in FIGS. 7 and 8, by way of non-limiting example, in the first state, the tire 10 rolls on a flat surface while carrying a load (i.e., normal operation), and the non-pneumatic tire 10 deforms, but the adjacent spokes 200 do not contact each other. The absence of contact between adjacent spokes 200 during normal operation is desirable to avoid the generation of unnecessary stress in the structure of the non-pneumatic tire 10.

[0036] The non-pneumatic tire 10 is expected to be subjected to high shock events such as hitting a curb, pothole, or other obstacle or road defect during its lifetime. During a high shock event, the non-pneumatic tire 10 may deform at a level significantly higher than the deformation that occurs during normal operation. An example of a high shock event is when the non-pneumatic tire 10 hits a curb at low speed (e.g., 5 miles per hour (8 kilometers per hour) against a 6-inch (15-centimeter) curb). Another example of a high shock event is when the non-pneumatic tire 10 hits a stepped road defect at high speed (e.g., 70 miles per hour (113 kilometers per hour) against a 1-inch (2.5-centimeter) defect). These are merely examples and do not limit the definition of a "high shock event."

[0037] Figures 9 and 10 show a tire in an exemplary second state, which is different from the first state. As shown in Figures 9 and 10, according to non-limiting examples, in the second state, the non-pneumatic tire 10 experiences a high-impact event of rolling on a non-flat surface. According to one non-limiting example, the non-flat surface is a road defect that protrudes above the ground or sinks into the ground over a distance of 3 inches (8 cm). According to another non-limiting example, the non-flat surface is a road defect that protrudes above the ground or sinks into the ground over a distance of 4.5 inches (11 cm). According to yet another non-limiting example, the non-flat surface is a road defect that protrudes above the ground or sinks into the ground over a distance of 6 inches (15 cm).

[0038] The non-pneumatic tire 10 responds to the high-impact event by deforming such that adjacent spokes 200 contact each other. Surprisingly, it has been found that the contact between adjacent spokes 200 during the high-impact event significantly reduces the stress experienced by each individual spoke 200 as compared to a non-pneumatic tire in which the spokes do not contact each other during the high-impact event. The reduction in stress in each individual spoke 200 is a result of the contact between adjacent spokes 200, as the contact distributes the load among multiple spokes 200. In other words, rather than a single spoke 200 absorbing the load resulting from the high-impact event, multiple spokes 200 share the same load, thus reducing the peak load on any one individual spoke 200.

[0039] In the illustrated embodiment, the non-pneumatic tire 10 is arranged and configured such that at least three adjacent spokes 200 contact each other simultaneously during a high-impact event, and the contacting spokes 200 are positioned adjacent to an obstacle or road defect that is the cause of the high-impact event. In an alternative embodiment, the non-pneumatic tire may be arranged and configured to have fewer or greater numbers of adjacent spokes that contact each other simultaneously during a high-impact event. In other alternative embodiments, the adjacent spokes that contact each other simultaneously may be positioned at any location along the circumferential direction of the tire (i.e., may be spaced apart from the obstacle or road defect that causes the high-impact event).

[0040] The design parameters of the spokes 200 and other components of the non-pneumatic tire 10 may be varied to provide the non-pneumatic tire 10 with desired performance characteristics. Preferably, these design parameters are selected such that contact between adjacent spokes 200 occurs before the spokes 200 begin to yield or otherwise sustain any form of damage.

[0041] Base plane p 1 The maximum distance d between the knee portion 222 along the direction perpendicular to the base plane p 1 and the base plane p 3 affects the stiffness of the spokes and when contact between adjacent spokes 200 occurs. Increasing the distance d 3 physically moves each spoke 200 closer to the adjacent spokes 200, and thus causes contact between adjacent spokes 200 to occur relatively earlier. Additionally, increasing the distance d 3 decreases the stiffness of the spokes 200, and thus increases the amount of deflection for a given load, which in turn increases the likelihood of contact between adjacent spokes 200. Decreasing the distance d 3 has the opposite effect, physically moving each spoke 200 farther from the adjacent spokes 200, and thus causing contact between adjacent spokes 200 to occur relatively later. Additionally, the distance d 3Reducing it increases the stiffness of the spoke 200, and thus reduces the amount of deflection for a given load, thereby reducing the likelihood of contact between adjacent spokes 200.

[0042] Base plane p 1 The transition portion 224 along the direction parallel to and the first radius of curvature r of the knee portion 222 1 The distance d between the center of 2 affects when contact with adjacent spokes 200 occurs. The distance d 2 being a greater proportion of d 1 results in contact between adjacent spokes 200 occurring relatively early. The distance d 2 being a smaller proportion of d 1 results in contact between adjacent spokes 200 occurring relatively late.

[0043] The radius of curvature r of the knee portion 222 1 affects when contact with adjacent spokes 200 occurs. Reducing the radius of curvature r 1 results in contact between adjacent spokes 200 occurring relatively late, and increasing the radius of curvature r 1 results in contact between adjacent spokes 200 occurring relatively early. The spoke thickness t affects the stiffness of the spoke 200. Increasing the spoke thickness t increases the stiffness of the spoke 200, and reducing the spoke thickness decreases the stiffness of the spoke 200.

[0044] In addition, it has been found that the vertical stiffness of the tire is affected by the combination of the spoke thickness t and the distance d 3 Increasing the distance d 3 decreases the tire stiffness, and reducing the distance d 3 increases the tire stiffness. As a result, in order to meet the target value of the tire stiffness, spokes with a larger thickness t should be combined with a larger distance d 3 and spokes with a smaller thickness t should be combined with a smaller distance d 3It has been found that it should be combined with.

[0045] FIG. 11 is a flowchart showing an exemplary method of manufacturing a non-pneumatic tire. At 1010, a lower ring and an upper ring are provided. The lower ring and the upper ring having a first diameter have a second diameter larger than the first diameter. At 1020, a plurality of spokes are formed. The spokes may be formed using hot stamping, cold forming, extrusion, rolling, bending, or any other desired method. In addition, the spokes may be formed using a plurality of composite manufacturing techniques (e.g., resin transfer molding and high-pressure resin transfer molding). Further examples of methods for forming the spokes include wet lay-up and prepreg lamination. Each spoke extends between a first end and a second end. A knee portion is located between the first end and the second end, and a transition portion is located between the first end and the knee portion. The knee portion and the transition portion are curved concave in opposite directions. A foot portion extends from the transition portion.

[0046] At 1030, a flexure member is attached to the spokes. At 1040, the spokes are arranged in a first group of spokes and a second group of spokes axially spaced from the first group of spokes. Further, a plurality of spokes in the first group of spokes are arranged to be curved concave with respect to a first circumferential direction of the tire, and a plurality of spokes in the second group of spokes are arranged to be curved convex with respect to the first circumferential direction of the tire.

[0047] At 1050, the lower ring is connected to the upper ring using the first group of spokes and the second group of spokes. The foot portion of each spoke is attached to the lower ring so as to connect the first end of each spoke to the lower ring. The flexure member is attached to the upper ring so as to connect the second end of each spoke to the upper ring.

[0048] In alternative embodiments, the foregoing steps may be performed in an order other than that specifically described. In other alternative embodiments, the method may include more or fewer steps.

[0049] Figures 12 and 12a show another embodiment of the spoke 1200. The spoke 1200 of Figures 12 and 12a is substantially the same as the spoke 200 of Figures 1 - 10, except for the differences described herein. Accordingly, like features will be identified by like numbers increased by a factor of "1000". In the spoke 200 shown in Figures 1 - 10, the second connection portion 228 is linear. In comparison, the spoke 1200 of Figures 12 and 12a has a curved second connection portion 1228 with a radius of curvature r 3 The curved second connection portion 1228 of the spoke 1200 in Figures 12 and 12a significantly improves the self - supporting behavior as compared to the linear second connection portion. According to one exemplary embodiment, the radius of curvature r 3 is from 10 to 50 inches (25 - 127 cm).

[0050] In addition to the design parameters and resulting performance characteristic changes described above with respect to the spoke 200 shown in Figures 1 - 10, the radius of curvature r of the curved second connection portion 1228 in the spoke 1200 of Figures 12 and 12a 3 can be varied to affect performance. The radius of curvature r of the curved second connection portion 1228 3 and the length l of the flexure member 1216 flexure interact to affect the self - supporting performance. A smaller radius of curvature r of the curved second connection portion 1228 3 decreases self - support and thus increases the stress during a high - impact event. A larger radius of curvature r of the curved second connection portion 1228 3 increases self - support and thus decreases the stress during a high - impact event. However, this stress reduction only occurs up to a point. As the radius of curvature r 3 increases (the limit being a radius of curvature r equal to infinity 3and the effectiveness of self - support begins to decrease again, resulting in a linear second connection part).

[0051] The length l of the flexure member 1216 flexure affects its ability to exert torque on the end of the spoke 1200. This torque acts to straighten the curved second connection part 1228 when the tire rolls under standard load or when it undergoes a high - impact event. As a result, a curved second connection part 1228 with a smaller radius of curvature r 3 is optimally matched with a flexure member 1216 having a longer length l flexure and a curved second connection part 1228 with a larger radius of curvature r 3 is found to be optimally matched with a flexure member 1216 having a shorter length l flexure It has been found. The ability of the flexure member 1216 to exert torque on the spoke 1200 is, in addition to the length l of the flexure member 1216 flexure affected by the rigidity of the material used to manufacture the flexure member 1216. As a result, when a softer material is used, a flexure member 1216 with a longer length l flexure is provided, and when a harder material is used, it is desirable to provide a flexure member 1216 with a shorter length l flexure

[0052] FIG. 13 shows another embodiment of the spoke 2200. The spoke 2200 of FIG. 13 is substantially the same as the spoke 200 of FIGS. 1 - 10 except for the differences described herein. Accordingly, similar features will be identified by similar numbers increased by a factor of "2000".

[0053] ​The spoke 2200 extends between a first end 2206 and a second end 2208. A foot portion 2214 is provided toward the first end 2206 of the spoke 2200. The foot portion 2214 is attached to the lower ring 20 so as to connect the first end 2206 of the spoke 2200 to the lower ring 20. A flexure member 2216 is provided at the second end 2208 of the spoke 2200. The flexure member 2216 is used to connect the second end 2208 of the spoke 2200 to the upper ring 30.

[0054] The spoke 2200 includes a knee portion 2222 between the first end 2206 and the second end 2208. A transition portion 2224 is provided between the knee portion 2222 and the first end 2206. The foot portion 2214 extends from the transition portion 2224 to the first end 2206 of the spoke 2200. A first connection portion 2226 connects the transition portion 2224 to the knee portion 2222. A second connection portion 2228 connects the knee portion 2222 to the second end 2208 of the spoke 2200. The base plane p 1 intersects the transition portion 2224 and the second end 2208 of the spoke 2200, and a second plane p 2 extends in a tangential direction with respect to the lower ring 20 at the transition portion 2224. The base plane p 1 and the second plane p 2 The angle between them is α.

[0055] In the embodiment of the spoke 2200 shown in FIG. 13, the angle α has a negative value as compared with the spoke 200 of FIGS. 1 to 10 in which the angle α has a positive value. As used herein, a positive value of the angle α uses the intersection point between the base plane p 1 and the second plane p 2 as a central point that moves clockwise, and the base plane p 1 is positioned in front of the second plane p 2 This means. Using this same reference system, a negative value of the angle α means that the base plane p 1 is the second plane p 2It means being positioned after. According to an exemplary embodiment, in the spoke 2200 shown in FIG. 13, the angle α is from -30 to 0 degrees. The fact that the angle α is a negative value may result in reducing the spoke stress as compared with a spoke having a positive value of the angle α.

[0056] The non-pneumatic tire described herein improves the robustness of the non-pneumatic tire by providing an arrangement in which adjacent spokes contact each other during a high-impact event. The contact between adjacent spokes results in a plurality of spokes sharing the load, and thus significantly reduces the stress received by any single spoke within the non-pneumatic tire. Thereby, the durability of the non-pneumatic tire is improved.

[0057] As used in this specification or the claims, the terms "includes" or "including" are intended to be inclusive, as is the term "comprising", when interpreted as used in a claim as a transitional word. Further, where the term "or" is used (e.g., A or B), it is intended to mean "A or B, or both". Where Applicants intend to indicate "only A or B but not both", the term "only A or B but not both" is used. Accordingly, the use of the term "or" in this specification is inclusive and not exclusive. See Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d Ed. 1995). Also, as used in this specification or the claims, the terms "in" or "into" are intended to additionally mean "on" or "onto". Further, as used in this specification or the claims, the term "connect" is intended to mean not only "directly connected to", but also "indirectly connected to", such as through one or more other components.

[0058] Although this application has been illustrated by the description of its embodiments and has been described in considerable detail, it is not the intention of the applicants to limit the appended claims to such detail or in any way. Additional advantages and modifications will readily occur to those skilled in the art. Accordingly, this application in its broader aspects is not limited to the specific details, representative apparatus and methods, and examples shown and described. For example, each spoke may be provided with a rubber coating to cushion the impact when contact occurs between adjacent spokes or to reduce friction or wear during such contact. Thus, departures from such details may be made without departing from the spirit or scope of the general inventive concept of the applicant.

Claims

1. A non-pneumatic tire, comprising: a lower ring having a first diameter; an upper ring having a second diameter and substantially coaxial with the lower ring; a support structure connecting the lower ring to the upper ring and composed of a plurality of spokes, the plurality of spokes being arranged in at least a first spoke group and a second spoke group axially spaced from the first spoke group, and each of the plurality of spokes comprising: a first end connected to the lower ring; a second end connected to the upper ring; and a knee portion located between the first end and the second end and curved concave with respect to the lower ring.

2. The spokes of the first spoke group are curved concave with respect to a first circumferential direction of the tire, and the spokes of the second spoke group are curved convex with respect to the first circumferential direction of the tire. The non-pneumatic tire according to claim 1.

3. Each of the plurality of spokes further includes a flexure member, and the flexure member is attached to the spoke and the upper ring so as to connect the second end of the spoke to the upper ring. The non-pneumatic tire according to claim 1.

4. Each of the plurality of spokes further includes a connecting portion connecting the knee portion to the second end, and the connecting portion is curved. The non-pneumatic tire according to claim 1.

5. Each of the plurality of spokes further includes a transition portion located between the first end and the knee portion, and the transition portion is curved convex with respect to the lower ring. The non-pneumatic tire according to claim 1.

6. Each of the plurality of spokes further includes a foot portion, the foot portion extending from the transition portion, the foot portion being attached to the lower ring so as to connect the first end of the spoke to the lower ring, and the foot portion being substantially straight. The non-pneumatic tire according to claim 5.

7. Each of the plurality of spokes further includes a foot portion, the foot portion extends from the transition portion, the foot portion is attached to the lower ring so as to connect the first end of the spoke to the lower ring, the foot portion is substantially curved and has a first radius of curvature substantially equal to a second radius of curvature of the lower ring, the non-pneumatic tire according to claim 5.

8. The base plane intersects the transition portion and the second end of the spoke, and a first angle is defined as the angle between the base plane and a plane extending tangentially to the lower ring at the transition portion, and the first angle has a value of -30 to +20 degrees, the non-pneumatic tire according to claim 5.

9. A first distance is defined as the distance between the transition portion and the second end of the spoke along a direction parallel to the base plane, the first distance has a value of 10 to 25 inches (25 to 63 cm), a second distance is defined as the distance between the transition portion and the center of the radius of curvature of the knee portion along a direction parallel to the base plane, the second distance has a value of 20 to 70 percent of the value of the first distance, a third distance is defined as the maximum distance between the base plane and the knee portion along a direction perpendicular to the base plane, the third distance has a value of 2 to 4 inches (5 to 10 cm), the non-pneumatic tire according to claim 8.

10. The non-pneumatic tire is arranged and configured such that at least three adjacent spokes of the plurality of spokes contact each other when a high-impact event occurs, the non-pneumatic tire according to claim 1.

11. A method of manufacturing a non-pneumatic tire, providing a lower ring having a first diameter and an upper ring having a second diameter larger than the first diameter; forming a plurality of spokes, each spoke extending between a first end and a second end, and each spoke including a knee portion located between the first end and the second end; arranging the plurality of spokes into a first group of spokes and a second group of spokes axially spaced from the first group of spokes; connecting the lower ring to the upper ring using the first group of spokes and the second group of spokes.

12. The step of arranging the plurality of spokes into the first spoke group and the second spoke group includes a sub-step of arranging the spokes of the first spoke group to be concave-curved with respect to the first circumferential direction of the tire, and arranging the spokes of the second spoke group to be convex-curved with respect to the first circumferential direction of the tire. The method for manufacturing a non-pneumatic tire according to claim 11.

13. The method for manufacturing a non-pneumatic tire according to claim 11 further includes a step of attaching a flexure member to each spoke and a step of attaching the flexure member to the upper ring. The step of attaching the flexure member to the upper ring is to connect the second end of the spoke to the upper ring while connecting the lower ring to the upper ring.

14. The method for manufacturing a non-pneumatic tire according to claim 11, wherein each spoke further includes a transition portion between the first end and the knee portion, and the knee portion and the transition portion are concave-curved in opposite directions.

15. The step of forming the plurality of spokes further includes a sub-step of forming a foot portion extending from the transition portion and attaching the foot portion to the lower ring. The sub-step of attaching the foot portion to the lower ring is to connect the first end of the spoke to the lower ring while connecting the lower ring to the upper ring. The method for manufacturing a non-pneumatic tire according to claim 15.

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