Mounting arrangement of a self-supporting spoke structure for a non-pneumatic tire - Patent Application 20070122

Abstract

The 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] This disclosure relates to non-pneumatic tires, and more particularly to non-pneumatic tires having a support structure with spokes designed to contact each other during a high impact event. [Background technology]

[0002] Various tire designs have been developed that allow the tire to run in an uninflated or under-inflated state. Non-pneumatic tires do not require inflation, while "run-flat tires" can continue to operate for extended periods and at relatively high speeds after being partially or completely deflated due to a puncture. Non-pneumatic tires may include support structures such as spokes or webbing that connect the lower ring to the 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 a 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 partially or uninflated pneumatic tire, the shear element acts as a structural compression member. When used in a fully inflated pneumatic tire, the shear element acts as a tension member.

[0004] Tire design, for both pneumatic and non-pneumatic tires, involves balancing many factors, including but not limited to load capacity, handling, and ride comfort. Regardless of the balance selected between these factors, non-pneumatic tires must be durable and able to withstand high-impact events, such as hitting a curb, pothole, or other obstacle or road defect. Summary of the Invention

[0005] In one embodiment, a non-pneumatic tire includes a lower ring having a plurality of scallops. Each of the plurality of scallops has a first curved surface. An upper ring is substantially coaxial with the lower ring. A support structure connects the lower ring to the upper ring. The support structure is comprised of a plurality of spokes. 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. Each of the plurality of spokes includes a first end connected to the lower ring and a second end connected to the upper ring. Each of the plurality of spokes further includes a first surface and a second surface facing opposite the first surface. Each of the first and second surfaces extends between the first and second ends. A foot portion is provided toward the first end of the spoke. The first surface of the spoke at the foot portion is the second curved surface. A second curved surface is attached to the first curved surface of one of the plurality of scallops to connect the first end of the spoke to the lower ring.

[0006] In another embodiment, a method for 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 scallops are formed on the lower ring. Each of the plurality of scallops has a first curved surface. A plurality of spokes are formed, each having a first surface and a second surface facing opposite the first surface. The first and second surfaces each extend between a first end and a second end. Forming the plurality of spokes includes providing a foot portion toward the first end of the spoke. The first surface of the spoke in the foot portion is the second curved surface. The lower ring is connected to the upper ring using a first group of spokes and a second group of spokes. Connecting the lower ring to the upper ring includes attaching the second curved surface of the spoke in the foot portion to the first curved surface of one of the plurality of scallops to connect the first end of the spoke to the lower ring and connecting the second end of the spoke to the upper ring.

[0007] In yet another embodiment, a non-pneumatic tire includes a lower ring having a first radius of curvature. The lower ring includes a plurality of scallops. Each scallop has a first curved surface having a second radius of curvature. An upper ring is substantially coaxial with the lower ring. A support structure connects the lower ring to the upper ring. The support structure is comprised of a plurality of spokes. Each spoke extends between a first end and a second end and includes a first surface and a second surface facing opposite the first surface. Each of the first and second surfaces extends between the first and second ends. The spokes include foot portions toward the first end. The first surfaces of the spokes at the foot portions are second curved surfaces having a third radius of curvature. Each of the first and second radii of curvature is different from the third radius of curvature. [Brief explanation of the drawings]

[0008] The accompanying drawings, together with the detailed description provided below, illustrate structures that describe exemplary embodiments of the claimed invention. Similar elements are identified with the same reference numerals. It should be understood that elements shown as a single component may be replaced by multiple components, and that elements shown as multiple components may be replaced by a single component. The drawings are not to scale, and the proportions of certain elements may be exaggerated for illustrative purposes. [Figure 1] FIG. 1 is a side view of one embodiment of a non-pneumatic tire. [Figure 2] FIG. 2 is another side view of the non-pneumatic tire of FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. [Figure 4] FIG. 4 is a detailed view of area A in FIG. [Figure 5] FIG. 5 is a detailed view of area A of FIG. 1 with some features removed for clarity. [Figure 6] FIG. 6 is a detailed view of a single spoke used in the non-pneumatic tire of FIG. [Figure 7]FIG. 7 is a side view of a portion of the non-pneumatic tire of FIG. 1 when the tire is on a flat surface and carrying a normal load. [Figure 8] FIG. 8 is a side view of a portion of the non-pneumatic tire of FIG. 1 when the tire is on a flat surface and carrying a normal load, with some features removed for clarity. [Figure 9] FIG. 9 is a side view of a portion of the non-pneumatic tire of FIG. 1 when the tire is on an uneven surface. [Figure 10] FIG. 10 is a side view of a portion of the non-pneumatic tire of FIG. 1 when the tire is on an uneven surface, with some features removed for clarity. [Figure 11] FIG. 11 is a flow chart illustrating a method of manufacturing the non-pneumatic tire of FIG. [Figure 12] FIG. 12 is another embodiment of a spoke for a non-pneumatic tire. [Figure 12a] FIG. 12a is an end view of the spoke of FIG. 12 along II. [Figure 13] FIG. 13 is a side view of a non-pneumatic tire showing the effect of manufacturing tolerances on the spokes before the second ends of the spokes are attached to the upper ring. [Figure 14] 14 is a side view of the non-pneumatic tire of FIG. 13 after the second ends of the spokes have been attached to the upper ring. [Figure 15] FIG. 15 is a partial view of another embodiment of a non-pneumatic tire. [Figure 16] FIG. 16 is a detailed view of a single spoke used in the non-pneumatic tire of FIG. [Figure 17] FIG. 17 is a partial side view of another embodiment of a non-pneumatic tire. [Figure 18] FIG. 18 is a partial perspective view of the non-pneumatic tire of FIG. [Figure 19] FIG. 19 is another partial perspective view of the non-pneumatic tire of FIG. [Figure 20]FIG. 20 is a partial side view of yet another embodiment of a non-pneumatic tire. [Figure 21] FIG. 21 is a detailed view of a single spoke from the non-pneumatic tire of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following contains definitions of selected terms used herein. The definitions include various examples or forms of components that fall within the scope of the term and that may be used for implementation. The examples are not intended to be limiting. Both singular and plural forms of a term may fall within the scope of the definition.

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

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

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

[0013] As used herein, "tread" refers to that portion of the tire that comes into contact with the road or ground under normal inflation and normal load.

[0014] It should be understood that while similar terms are used in the following description to describe typical tire components, the terms, of course, have slightly different connotations and one of ordinary skill in the art would not consider any of the following terms to be purely interchangeable with another term used to describe a typical tire component.

[0015] As used herein, directions are stated with reference to the tire's axis of rotation. The terms "upward" and "upwardly" refer to the general direction toward the tire's tread, and "downward" and "downwardly" refer to the general direction toward the tire's axis of rotation. Thus, when relative directional terms such as "upper" and "lower" or "top" and "bottom" are used in connection with elements, 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 connection with elements, an element that is "above" another element is closer to the tread than the other element.

[0016] The terms "inner" and "inwardly" refer to the general direction toward the tire's equatorial plane, and "outer" and "outwardly" refer to the general direction away from the tire's equatorial plane, toward the tire's side. Thus, when relative directional terms such as "inner" and "outer" are used in connection with elements, the "inner" elements are spaced closer to the tire's equatorial plane than the "outer" elements.

[0017] 1-5 illustrate one embodiment of a non-pneumatic tire 10. The non-pneumatic tire 10 is merely an exemplary illustration 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 mounting 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 polymeric material, an elastomeric material, a metal, a composite material composed of a polymer reinforced with glass or carbon fiber, or any other desired material or combination of materials.

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

[0019] 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 alternative embodiments, the tread band may be a multi-layer band. Such a multi-layer tread band may include one or more layers of substantially inextensible material. The layers may be formed from sheets of material, cords of material, filaments of material, or any other desired arrangement. In other alternative embodiments, the multi-layer tread band may include layers of extensible material, such as an elastomer. According to one exemplary embodiment, the tread band may include a pair of inextensible layers separated by a layer of extensible material. In yet other alternative embodiments, the tread band may include bands referred to as shear bands, shear elements, or thin annular high strength band elements.

[0021] A 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 made up of a plurality of spokes 200. In the illustrated embodiment, the plurality of spokes 200 is arranged in two axially spaced-apart spoke groups, including a first group of spokes 202 and a second group of spokes 204 axially spaced from the first group of spokes 202. In alternative embodiments, the support structure may include three or more axially spaced-apart spoke groups.

[0022] As shown in Figure 3, the first group of spokes 202 and the second group of spokes 204 are axially spaced apart from one another. In alternative embodiments, the spacing between the first group of spokes and the second group of spokes may be greater or less, or the first and second group of spokes may be positioned with no spacing between them. From the perspective shown in Figure 1, each spoke 200 of the first group of spokes 202 is substantially convex with respect to the clockwise circumferential direction of the non-pneumatic tire 10, and each spoke of the second group of spokes 204 is substantially concave with respect to the clockwise circumferential direction of the non-pneumatic tire 10.

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

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

[0025] Towards the first ends 206 of the spokes 200 are integral foot portions 214. The first surfaces 210 of the spokes 200 at the foot portions 214 are attached to the outer surface 24 of the lower ring 20 to connect the first ends 206 of the spokes 200 to the lower ring 20. The foot portions 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), a key / keyway, or any other desired arrangement. In the illustrated embodiment, the foot portions 214 are substantially straight and are fixed to the outer surface 24 of the lower ring 20 along their entire length (the dimension of the foot portion extending circumferentially of the tire) and their entire width (the dimension of the foot portion extending axially of the tire). In alternative embodiments, the foot portions may be separate components attached to the spokes. In other alternative embodiments, the foot portions 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 below the outer surface of the lower ring, or the spokes may extend through the lower ring so that the foot portion may be attached to the inner surface of the lower ring.

[0026] The second ends 208 of the spokes 200 are provided with flexible members 216. The flexible members 216 have a width extending axially along the tire. The flexible members 216 may be fabricated from a polymer (e.g., urethane or rubber), a thin, curved piece of metal, or any other desired material or combination of materials. In the illustrated embodiment, the flexible members 216 are provided as rectangular parallelepipeds and are positioned such that the ends of the flexible members 216 are aligned with the second ends 208 of the spokes 200. In other alternative embodiments, the flexible members may be positioned such that the ends of the flexible members are set back from the second ends of the spokes or such that the ends of the flexible members extend beyond the second ends of the spokes. In yet other alternative embodiments, the flexible members may be replaced with mechanical pin joints (i.e., hinges).

[0027] The flexible members 216 include a spoke-facing surface 218 and a ring-facing surface 220. The spoke-facing surfaces 218 of the flexible members 216 are attached to the second surfaces 212 of the spokes 200, and the ring-facing surfaces 220 are attached to the inner surface 33 of the top ring 30, connecting the second ends 208 of the spokes 200 to the top ring 30. Attachment between the flexible members 216 and the spokes 200, or between the flexible members 216 and the top ring 30, may be achieved using welding, brazing, soldering, adhesives, mechanical fasteners (e.g., bolts, rivets), key / keyway, or any other desired arrangement. For example, attachment may be achieved by pouring urethane directly onto the spokes, with or without the spokes first being coated with a primer.

[0028] The flexible members 216 provide flexibility to the connection between the second ends 208 of the spokes 200 and the upper ring 30. This flexibility reduces the likelihood of high stresses developing within the spokes 200, thereby improving the robustness of the non-pneumatic tire 10. Compared to the flexible connection provided by the flexible members 216, the connection provided by the foot portions 214 at the first ends 206 of the spokes 200 is more rigid.

[0029] In alternative embodiments, the flexible members may have shapes or configurations different from those specifically shown and described. In other alternative embodiments, additional structure(s) or mechanism(s) may supplement the flexible members for attaching the second ends of the spokes to the upper ring. In still other alternative embodiments, the flexible members may be omitted, and the second ends of the spokes may be attached directly to the upper ring. In these alternative embodiments, the second ends of the spokes may be attached directly to the inner surface of the upper ring on or to the inner surface of the upper ring, or the spokes may extend through the upper ring such that the second ends may be attached to the outer surface of the upper ring.

[0030] The spokes 200 include a knee portion 222 between the first end 206 and the second end 208. The knee portion 222 has a first radius of curvature r1. According to one exemplary embodiment, the first radius of curvature r1 is between 2 and 6 inches (5 and 15 cm). When attached to the upper and lower rings 20, 30, the knee portion 222 is concavely curved relative 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 r2. According to one exemplary embodiment, the second radius of curvature r2 is between 0 and 2 inches (0 and 5 cm). When attached to the upper and lower rings 20, 30, the transition portion 224 is convexly curved relative to the lower ring 20. Thus, relative to a single spoke 200, the knee portion 222 and the transition portion 224 are concavely curved in opposite directions. In an alternative embodiment, the knee portion and the transition portion are concavely (or convexly) curved in the same direction.

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

[0033] The base plane p1 intersects the transition portion 224 and the second end 208 of the spoke 200 and serves as a reference for various dimensional aspects of the spoke 200. The angle between the base plane p1 and a second plane p2 extending tangent to the outer surface 24 of the lower ring 20 at the transition portion 224 is α. According to an exemplary embodiment, the angle α is between +0 and +20 degrees. The distance d1 between the transition portion 224 and the second end 208 of the spoke 200 along a direction parallel to the base plane p1 is d1. According to an exemplary embodiment, the distance d1 is between 10 and 25 inches (25 and 63.5 cm). The distance d2 between the center of the transition portion 224 and the center of the first curvature r1 of the knee portion 222 along a direction parallel to the base plane p1 is d2. According to an exemplary embodiment, the value of the distance d2 is between 20 and 70 percent of the distance d1. The maximum distance between the knee portion 222 and the base plane p1 along a direction perpendicular to the base plane p1 is d3. According to one exemplary embodiment, the distance d3 is 2 to 4 inches (5 to 10 cm).

[0034] 10, the transition portion 224 of one spoke 200 is separated from the first end 206 of an adjacent spoke 200 by a first spacing distance s1. The second ends 208 of adjacent spokes 200 are separated from each other by a second spacing distance s2 (see also FIG. 5).

[0035] A non-pneumatic tire constructed according to the above-described design parameters can provide a more robust assembly, particularly with respect to impact performance. Figures 7 and 8 show the tire in an exemplary first state. As shown in Figures 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 although the non-pneumatic tire 10 deforms, adjacent spokes 200 do not contact one another. The lack of contact between adjacent spokes 200 during normal operation is desirable to avoid creating unnecessary stresses in the structure of the non-pneumatic tire 10.

[0036] During its life, the non-pneumatic tire 10 is expected to be subjected to high-impact events, such as hitting a curb, pothole, or other obstacle or road imperfection. During a high-impact event, the non-pneumatic tire 10 may deform to a level significantly higher than that which occurs during normal operation. One example of a high-impact event is the non-pneumatic tire 10 striking a curb at a low speed (e.g., a 6-inch (15 centimeter) curb at 5 miles per hour (8 kilometers per hour)). Another example of a high-impact event is the non-pneumatic tire 10 striking a bumpy road imperfection at a high speed (e.g., a 1-inch (2.5 centimeter) curb at 70 miles per hour (113 kilometers per hour)). These are merely examples and are not intended to limit the definition of "high-impact event."

[0037] 9 and 10 illustrate a tire in an exemplary second condition, the second condition being different from the first condition. As shown in FIGS. 9 and 10, by way of a non-limiting example, in the second condition, the non-pneumatic tire 10 experiences a high-impact event in which the tire rolls over an uneven surface. By way of one non-limiting example, the uneven surface is a road imperfection that protrudes above or sinks into the ground over a distance of 3 inches (8 cm). By way of another non-limiting example, the uneven surface is a road imperfection that protrudes above or sinks into the ground over a distance of 4.5 inches (11 cm). By way of yet another non-limiting example, the uneven surface is a road imperfection that protrudes above or sinks into the ground over a distance of 6 inches (15 cm).

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

[0039] In the illustrated embodiment, the non-pneumatic tire 10 is positioned and configured so that at least three adjacent spokes 200 simultaneously contact each other during a high-impact event, and the contacting spokes 200 are located adjacent to the obstacle or road defect that caused the high-impact event. In alternative embodiments, the non-pneumatic tire may be positioned and configured to have fewer or more adjacent spokes simultaneously contacting each other during a high-impact event. In other alternative embodiments, the adjacent spokes simultaneously contacting each other may be located anywhere around the tire (i.e., located away from the obstacle or road defect that caused 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 desired performance characteristics for the non-pneumatic tire 10. Preferably, these design parameters are selected so that contact between adjacent spokes 200 occurs before the spokes 200 begin to yield or suffer any other form of damage.

[0041] The maximum distance d3 between the knee portion 222 and the base plane p1 along a direction perpendicular to the base plane p1 affects the stiffness of the spokes 200 and when contact between adjacent spokes 200 occurs. Increasing the distance d3 physically moves each spoke 200 closer to its adjacent spokes 200, thus causing contact between adjacent spokes 200 to occur relatively sooner. Additionally, increasing the distance d3 decreases the stiffness of the spokes 200, thus increasing the amount of deflection for a given load, thereby increasing the likelihood of contact between adjacent spokes 200. Decreasing the distance d3 has the opposite effect, moving each spoke 200 physically farther from its adjacent spokes 200, thus causing contact between adjacent spokes 200 to occur relatively late. Additionally, decreasing the distance d3 increases the stiffness of the spokes 200, thus decreasing the amount of deflection for a given load, thereby decreasing the likelihood of contact between adjacent spokes 200.

[0042] The distance d2 between the transition portion 224 and the center of the first radius of curvature r1 of the knee portion 222 along a direction parallel to the base plane p1 affects when contact occurs with adjacent spokes 200. When the distance d2 is a larger percentage of d1, this results in contact between adjacent spokes 200 occurring relatively sooner. When the distance d2 is a smaller percentage of d1, this results in contact between adjacent spokes 200 occurring relatively late.

[0043] The radius of curvature r1 of the knee portion 222 affects when contact occurs with adjacent spokes 200. Decreasing the radius of curvature r1 results in contact between adjacent spokes 200 occurring relatively later, while increasing the radius of curvature r1 results in contact between adjacent spokes 200 occurring relatively sooner. The spoke thickness t affects the stiffness of the spokes 200. Increasing the spoke thickness t increases the stiffness of the spokes 200, while decreasing the spoke thickness decreases the stiffness of the spokes 200.

[0044] Additionally, it was found that tire vertical stiffness is affected by the combination of spoke thickness t and distance d3. Increasing distance d3 decreases tire stiffness, while decreasing distance d3 increases tire stiffness. As a result, it was found that to meet the tire stiffness target, spokes with a larger thickness t should be combined with a larger distance d3, and spokes with a smaller thickness t should be combined with a smaller distance d3.

[0045] FIG. 11 is a flowchart illustrating an exemplary method for manufacturing a non-pneumatic tire. At 1010, a lower ring and an upper ring are provided. The lower ring and the upper ring have a first diameter and a second diameter greater 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. Additionally, the spokes may be formed using a plurality of composite fabrication techniques (e.g., resin transfer molding and high-pressure resin transfer molding). Further examples of methods for forming the spokes include wet layup 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 concavely curved in opposite directions. A foot portion extends from the transition portion.

[0046] At 1030, flexible members are 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, the spokes of the first group of spokes are arranged to curve concavely relative to a first circumferential direction of the tire, and the spokes of the second group of spokes are arranged to curve convexly relative to the first circumferential direction of the tire.

[0047] At 1050, the lower ring is connected to the upper ring using first and second groups of spokes, with the foot of each spoke attached to the lower ring to connect a first end of each spoke to the lower ring, and a flexible member attached to the upper ring to connect a second end of each spoke to the upper ring.

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

[0049] FIGS. 12 and 12a illustrate another embodiment of a spoke 1200. The spoke 1200 of FIGS. 12 and 12a is substantially similar to the spoke 200 of FIGS. 1-10, except for the differences described herein. Accordingly, similar features will be identified by similar numerals increased by a factor of 1000. In the spoke 200 shown in FIGS. 1-10, the second connecting portion 228 is straight. In comparison, the spoke 1200 of FIGS. 12 and 12a has a curved second connecting portion 1228 having a radius of curvature r3. Compared to a straight second connecting portion, the curved second connecting portion 1228 of the spoke 1200 of FIGS. 12 and 12a significantly improves self-supporting behavior. According to one exemplary embodiment, the radius of curvature r3 is 10 to 50 inches (25 to 127 cm).

[0050] In addition to varying the design parameters and resulting performance characteristics described above for the spoke 200 shown in Figures 1-10, the radius of curvature r3 of the curved second connecting portion 1228 in the spoke 1200 of Figures 12 and 12a can be varied to affect performance. The radius of curvature r3 of the curved second connecting portion 1228 and the length l of the flexible member 1216 can be varied to affect performance. flexure These factors interact to affect the self-supporting performance. A smaller radius of curvature r3 of the curved second connecting portion 1228 reduces self-support and therefore increases stress during high-impact events. A larger radius of curvature r3 of the curved second connecting portion 1228 increases self-support and therefore reduces stress during high-impact events. However, this stress reduction only occurs up to a point. As the radius of curvature r3 increases (the limit is a radius of curvature r3 equal to infinity, resulting in a straight second connecting portion), the effectiveness of self-support begins to decrease again.

[0051] Length l of flexible member 1216 flexureThe radius of curvature r3 affects the ability of the spoke 1200 to exert a torque on the end of the spoke 1200. This torque acts to straighten the curved second connecting portion 1228 when the tire rolls under normal load or is subjected to a high impact event. As a result, the curved second connecting portion 1228 having a smaller radius of curvature r3 will have a longer length l flexure The curved second connecting portion 1228, having a larger radius of curvature r3, is optimally aligned with the flexible member 1216 having a shorter length l flexure It has been found that the ability of the flexure 1216 to exert torque on the spokes 1200 is optimally matched with a flexure 1216 having a length l of the flexure 1216. flexure In addition to , it is also affected by the stiffness of the material used to manufacture the flexible member 1216. As a result, if a softer material is used, a longer length l flexure and if a stiffer material is used, a shorter length l flexure It is desirable to provide a flexible member 1216 having

[0052] The non-pneumatic tires described herein improve the robustness of non-pneumatic tires by providing an arrangement in which adjacent spokes contact each other during high impact events. The contact between adjacent spokes results in multiple spokes sharing the load, thus significantly reducing the stress experienced by any single spoke within the non-pneumatic tire. This improves the durability of the non-pneumatic tire.

[0053] In the above-described embodiment, the foot portions 214 of the spokes 200 are initially substantially straight and are bonded to the curved outer surface 24 of the lower ring 20. This bonding process causes the foot portions 214 to conform to the curvature of the outer surface 24. While this arrangement results in a relatively simple manufacturing process for the spokes 200 and lower ring 20, it can create other potential design challenges. For example, in flat foot portion embodiments, the primary applied force acting at the joint between the spoke and the ring is a tensile force. This tensile force can cause a split-type failure at the leading edge of the spoke. As another example, the rotational position of each spoke relative to the lower and upper rings cannot be adjusted without introducing undesirable prestress into the spoke.

[0054] Spoke rotation adjustments may be necessary to account for manufacturing tolerances. Ideally, all spokes in a non-pneumatic tire would be identical, including the dimensions of various elements (e.g., the lengths of the foot portion, first connecting portion, and second connecting portion) and the angles between these elements (e.g., the angle between the foot portion and the first connecting portion, or the angle between the first connecting portion and the second connecting portion). In practice, however, it is unlikely that all spokes will be identical. Manufacturing guidelines acknowledge variables in the formed features of the product, such as material thickness and tempering tolerances. Additionally, these manufacturing guidelines acknowledge variables in the angle tolerance for bending, with one guideline suggesting a tolerance of + / - 1 degree.

[0055] Figures 13 and 14 illustrate how this + / - 1 degree tolerance can affect the support structure of a non-pneumatic tire. The non-pneumatic tire of Figures 13 and 14 is constructed in accordance with the non-pneumatic tire embodiment of Figures 1-6. Accordingly, like features will be identified by like numerals.

[0056] 13 and 14 show a first spoke 200a, a second spoke 200b, and a third spoke 200c. In the first spoke 200a and the third spoke 200c, the angle θ between the foot portion 214 and the first connecting portion 226 is 1 degree less than the specified design value, while in the second spoke 200b, this angle θ is 1 degree greater than the design value. FIG. 13 shows the spokes 200 when the foot portion 214 is connected to the lower ring 20 and the second end 208 of each spoke 200 is in its natural or rest position (i.e., the location of the second end 208 of the spoke 200 without any external force applied and before the flexible member 216 is attached to the upper ring 30). FIG. 14 shows the spokes 200 after the second end 208 of the spoke 200 has been moved to the desired location and the flexible member 216 has been attached to the upper ring 30. As shown in FIG. 13 , if the angle between the foot portion 214 and the first connecting portion 226 is out of specification by even one degree, it can cause various problems, including the flexible member 216 naturally resting above the upper ring 30 (second spoke 200b) or naturally resting below the upper ring 30 (first and third spokes 200a, 200c), and having irregular spacing between adjacent spokes 200. Some of these problems could be corrected by pressing the second end 208 of each spoke 200 into the desired position, as shown in FIG. 14 , but doing so introduces undesirable prestress into the spokes 200. In theory, each spoke 200 could be rotated about its first end 206 to correct these problems. However, in practice, such rotation is not possible due to the geometry between the flat foot portion 214 and the exterior surface of the lower ring 20.

[0057] Figure 15 illustrates an alternative embodiment of a portion of a non-pneumatic tire having features that alleviate the above-mentioned problems with manufacturing tolerances. Figure 16 illustrates a single spoke of the non-pneumatic tire of Figure 15. The arrangements illustrated in Figures 15 and 16 are substantially similar to the arrangements illustrated in Figures 1-6, except for any differences described herein. Accordingly, like features will be identified by like numerals increased by the value "2000."

[0058] The non-pneumatic tire 2010 includes a support structure 2100 that connects a lower ring 2020 to an upper ring (not shown). The support structure 2100 is made up of a plurality of spokes 2200 arranged in first and second groups of spokes (not shown). The first and second groups of spokes are offset and spaced apart from one another in the axial direction of the non-pneumatic tire 2010.

[0059] 16 , each spoke 2200 extends between a first end 2206 and a second end 2208 and includes a first surface 2210 and a second surface 2212. A foot portion 2214 is provided toward the first end 2206 of the spoke 2200. A flexible member 2216 is provided at the second end 2208 of the spoke 2200. A knee portion 2222 is provided 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 toward the first end 2206 of the spoke 2200. A first connecting portion 2226 connects the transition portion 2224 to the knee portion 2222 , and a second connecting portion 2228 connects the knee portion 2222 to the second end 2208 of the spoke 2200 .

[0060] The outer surface 2024 of the lower ring 2020 is provided with a number of scallops 2025 equal to the total number of spokes 2200 in the support structure 2100 (only a single scallop is shown in FIG. 15). The first surfaces 2210 of the spokes 2200 in the foot portion 2214 are curved, with the corresponding scallops 2025 having a radius of curvature r s radius of curvature r equal to fpThe scallops 2025 are spaced from one another along the circumferential direction of the non-pneumatic tire 2010 and are arranged in first and second scallop groups (not shown). Similar to the separation between the first and second groups of spokes, the scallops are also offset and spaced from one another axially of the non-pneumatic tire 2010. The curved first surfaces 2210 of the spokes 2200 in the foot portion 2214 are bonded to the respective scallops 2025 to attach the first ends of the spokes 2200 to the lower ring 2020. Flexible members 2216 are bonded to the upper ring 2030 to connect the second ends 2208 of the spokes 2200 to the upper ring 2030. In alternative embodiments, the foot portion or flexible members may be attached to the scallops or upper ring, respectively, using any desired arrangement. For example, the curved first surfaces of the spokes in the foot portions may be attached to their respective scallops using a nut and bolt arrangement, whereby the bolts extend into through holes on the spokes and lower ring, exposing threads that receive the nuts. This nut and bolt attachment may also be used to attach the flexible member to the upper ring. In other alternative embodiments, instead of separate groups of scallops, each scallop may extend continuously axially across the lower ring, and the spokes of the first and second groups of spokes may share their respective scallops.

[0061] The above-described arrangement helps solve potential design issues associated with flat foot spoke embodiments related to spoke manufacturing tolerances. By providing the non-pneumatic tire 2010 with spokes 2200 having curved foot portions 2214 and corresponding curved scallops 2205 on the lower ring 2020, the primary applied force acting at the interface between the spokes 2200 and the lower ring 2020 is shear, rather than tension, as occurs with flat foot embodiments. This change reduces the likelihood of a split-type failure mode occurring at the connection between the spokes 2200 and the lower ring 2020. Furthermore, shear forces acting at the interface between the spokes 2200 and the lower ring 2020 subject the interface to a substantially stronger failure mode with most commonly used adhesives.

[0062] Additionally, the curved surfaces of the spokes 2200 and scallops 2025 allow for adjustment of the rotational position of each spoke 2200 relative to the lower ring 2020 and upper ring 2030 without pre-introducing stress to the spokes as is the case with flat foot portion embodiments, and the curved surfaces of the spokes 2200 and scallops 2025 also allow a consistent adhesive gap to be maintained during such rotational adjustment.

[0063] Radius of curvature r at foot portion 2214 fp and the curvature radius r of the scallop 2025 s It has been found that certain design principles should be followed to provide the above-described flexibility with respect to rotational positioning. According to one exemplary design principle, the radius of curvature r at the foot portion 2214 fp and the curvature radius r of the scallop 2025 s is the radius of curvature r of the outer surface of the lower ring 2020 lr is different.

[0064] In the illustrated embodiment, the curved second surfaces 2212 of the spokes 2200 at the foot portions 2214 and the scallops 2025 are both convex relative to the inner surface 2023 of the lower ring 2020, and the radius of curvature r at the foot portions 2214 fpand the curvature radius r of the scallop 2025 s are both constant and equal to each other. Additionally, the scallops 2025 are formed directly on the lower ring 2020. In an alternative embodiment, the second surfaces of the spokes may be convex relative to the inner surfaces of the spokes, and the lower ring may be provided with corresponding bumps that are also convex relative to the inner surfaces of the spokes. In other alternative embodiments, the radius of curvature of the foot portions or the radii of curvature of the scallops or bumps may be variable or different from each other. In yet other alternative embodiments, the scallops or bumps may be formed on a sleeve secured to the outer surface of the lower ring.

[0065] Figures 17-19 illustrate another embodiment of a non-pneumatic tire 3010. The non-pneumatic tire 3010 of Figures 17-19 is substantially similar to the non-pneumatic tire 2010 of Figures 15 and 16, except for the differences described herein. Accordingly, like features will be identified by like numbers increased by a factor of "1000."

[0066] The non-pneumatic tire 3010 includes a support structure 3100 that connects a lower ring 3020 to an upper ring 3030. The support structure 3100 is made up of a plurality of spokes 3200 arranged in a first group of spokes and a second group of spokes (not shown). In the illustrated embodiment, for clarity, only a single row of spokes 3200 is shown, and the spokes 3200 extend the entire axial width of the lower ring 3020. However, if two groups of spokes are utilized, the lower ring 3020 may have an axial width that is at least twice the width of a single spoke.

[0067] Each spoke 3200 extends between a first end 3206 and a second end 3208. A foot portion 3214 is provided toward the first end 3206 of the spoke 3200. A flexible member 3216 is provided at the second end 3208 of the spoke 3200.

[0068] The lower ring 3020 is provided with a plurality of scallops 3024, the number of which is equal to the total number of spokes 3200 in the support structure 3100. The scallops 3024 are spaced from one another circumferentially around the non-pneumatic tire 3010 and are arranged in first and second groups of scallops (not shown). Similar to the separation between the first and second groups of spokes, the groups of scallops are also offset and spaced from one another axially around the non-pneumatic tire 3010. In alternative embodiments, each scallop may extend continuously across the lower ring in the axial direction, and the spokes of the first and second groups of spokes may share their respective scallops.

[0069] A mechanical fastening arrangement 3080 connects the foot portions 3214 of the spokes 3200 to the respective scallops 3205, attaching the first ends 3206 of the spokes 3200 to the lower ring 3020. An adhesive (not shown) can strengthen the connection by bonding these components together. The adhesive can prevent wear between the various components due to cyclic loading and can also prevent deterioration (e.g., corrosion) resulting from exposure to environmental elements. A flexible member 3216 is attached to the upper ring 3030 to connect the second ends 3208 of the spokes 3200 to the upper ring 3030.

[0070] In the illustrated embodiment, the mechanical fastening arrangement 3080 includes a clamping plate 3082 and two socket head cap screws 3084. The clamping plate 3082 has an axial width substantially the same as the foot portion 3214 and a face 3086 having a radius of curvature substantially the same as the radius of curvature of the foot portion 3214. In alternative embodiments, the axial width of the clamping plate may be greater or less than the axial width of the foot portion. In other alternative embodiments, the radius of curvature of the face of the clamping plate may be different from the radius of curvature of the foot portion.

[0071] Each mechanical fastening arrangement 3080 is configured such that the head of a socket head cap screw 3084 is located radially inward of the lower ring 3020 and the threads of the socket head cap screw 3084 pass through the lower ring 3020, the foot portion 3214, and the clamp plate 3082. The foot portion 3214 is provided with a through hole (not shown) to allow passage of the socket head cap screw 3084. The through hole may be oversized or provided as a slot to allow adjustment of the position of the spokes 3200 relative to the lower ring 3020.

[0072] The threaded portion of the socket head cap screw 3084 engages with internal threads on the clamp plate 3082, which is located radially outward of the foot portion 3214. In alternative embodiments, the orientation of the fastening arrangement may be reversed, with the head of the socket head cap screw located radially outward of the clamp plate and the threaded portion engaging with internal threads on the lower ring. In other alternative embodiments, the socket head cap screws may be provided in any desired location, may be any desired size, and may have a greater or lesser number of threads. In yet other alternative embodiments, the mechanical fastening arrangement, lower ring, and / or foot may be sized and configured such that the second fastener does not extend through the lower ring or clamp plate. In still other alternative embodiments, any desired mechanical fastening arrangement may be used (e.g., nuts and washers, studs or set screws with rivets).

[0073] The mechanical fastening arrangement 3080 may distribute the load across the axial width of the foot portion 3214 of the spoke 3200, thereby providing a stronger structure and a more rigid connection. Furthermore, the use of the clamping plate 3082 may facilitate construction of the non-pneumatic tire 3010 by eliminating the need for a clamping arrangement when adhesive alone is used. Additionally, the mechanical fastening arrangement 3080 allows for individual removal, maintenance, and installation of single spokes.

[0074] Figures 20 and 21 illustrate another embodiment of a non-pneumatic tire 4010. The non-pneumatic tire 4010 of Figures 20 and 21 is substantially similar to the non-pneumatic tire 3010 of Figures 17-19, except for the differences described herein. Accordingly, like features will be identified by like numbers increased by a factor of "1000."

[0075] The non-pneumatic tire 4010 includes a support structure 4100 that connects a lower ring 4020 to an upper ring 4030. The support structure 4100 is made up of a plurality of spokes 4200 arranged in a first group of spokes and a second group of spokes (not shown).

[0076] Each spoke 4200 extends between a first end 4206 and a second end 4208. A foot portion 4214 is provided toward the first end 4206 of the spoke 4200. A flexible member 4216 is provided at the second end 4208 of the spoke 4200. A knee portion 4222 is provided between the first end 4206 and the second end 4208. A transition portion 4224 is provided between the knee portion 4222 and the first end 4206. The foot portion 4214 extends from the transition portion 4224 toward the first end 4206 of the spoke 4200. A first connecting portion 4226 connects the transition portion 4224 to the knee portion 4222, and a second connecting portion 4228 connects the knee portion 4222 to the second end 4208 of the spoke 4200.

[0077] The lower ring 4020 is provided with a plurality of scallops 4024, the number of which is equal to the total number of spokes 4200 in the support structure 4100. The scallops 4024 are spaced from one another circumferentially around the non-pneumatic tire 4010 and are arranged in first and second groups of scallops (not shown). Similar to the separation between the first and second groups of spokes, the groups of scallops are also offset and spaced from one another axially around the non-pneumatic tire 4410. In alternative embodiments, each scallop may extend continuously across the lower ring in the axial direction, and the spokes of the first and second groups of spokes may share their respective scallops.

[0078] A mechanical fastening arrangement 4080 connects the foot portions 4214 of the spokes 4200 to the respective scallops 4205, attaching the first ends 4206 of the spokes 4200 to the lower ring 4020. The mechanical fastening arrangement 4080 is substantially the same as the mechanical fastening arrangement 3080 shown in FIGS. 17-19 and therefore will not be described further. An adhesive (not shown) can strengthen the connection by bonding these components together. The adhesive can prevent wear between the various components due to cyclic loading and can also prevent deterioration (e.g., corrosion) resulting from exposure to environmental elements. A flexible member 4216 is attached to the upper ring 4030 to connect the second ends 4208 of the spokes 4200 to the upper ring 4030.

[0079] As described above, in the embodiment of Figures 1-19, the knee portion and transition portion are concavely curved in opposite directions for a single spoke. In comparison, according to the embodiment of Figures 20 and 21, the knee portion 4222 and transition portion 4224 are concavely curved in the same direction. This arrangement may provide advantages regarding how the mechanical fastening arrangement 4080 and adhesive (if used) are subjected to loads and stresses. In particular, providing the knee portion 4222 and transition portion 4224 as concavely curved in the same direction can create a compression effect between the spoke 4200 and the lower ring 4020, which can reduce delamination issues and better distribute stress, thereby providing a more robust structure.

[0080] Although individual embodiments and variations are shown and described in Figures 1-21, the disclosed features are not limited to each of the described embodiments. Instead, various features can be combined between embodiments as desired. For example, the curved foot portion arrangement of the spokes shown in Figures 15 and 16 may be combined with the curved connecting portion of the spokes shown in Figures 12 and 12a.

[0081] The terms "includes" or "including," to the extent used in this specification or the claims, are intended to be inclusive, similar to the term "comprising," as interpreted when used as a transitional word in a claim. Furthermore, to the extent 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. Thus, the use of the term "or" herein is inclusive, not exclusive. See Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d. Ed. 1995). Also, the terms "in" or "into," to the extent used in this specification or the claims, are intended to additionally mean "on" or "onto." Furthermore, to the extent the term "connect" is used in this specification or the claims, it is intended to mean not only "directly connected to," but also "indirectly connected to," such as by connecting through one or more other components.

[0082] While the present application has been illustrated by the description of its embodiments, and those embodiments have been described in considerable detail, it is not the intention of applicants to restrict or in any way limit the scope of the appended claims to such details. Additional advantages and modifications will be readily apparent to those skilled in the art. Therefore, the present 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 impact when contact occurs between adjacent spokes. Thus, departures may be made from such details without departing from the spirit or scope of applicants' general inventive concept.

Claims

1. A non-pneumatic tire, a lower ring having a plurality of scallops, each of the plurality of scallops having a first curved surface; an upper ring substantially coaxial with the lower ring; a support structure connecting the lower ring to the upper ring, the support structure comprising a plurality of spokes, the plurality of spokes being arranged in 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 comprising: a first end connected to the lower ring; a second end connected to the upper ring; and a first surface and a second surface facing opposite the first surface, each of the first surface and the second surface extending between the first end and the second end; and foot portions provided toward the first ends of the spokes, the first surfaces of the spokes at the foot portions being second curved surfaces attached to the first curved surfaces of one of the scallops to connect the first ends of the spokes to the lower ring, the second surfaces of the spokes at the foot portions being positioned opposite the upper ring.

2. The non-pneumatic tire of claim 1 , wherein each of the first curved surface and the second curved surface is convex relative to an inner surface of the lower ring.

3. 10. The non-pneumatic tire of claim 1, wherein the first curved surface has a first radius of curvature and the second curved surface has a second radius of curvature, and at least one of the first radius of curvature and the second radius of curvature is constant.

4. 10. The non-pneumatic tire of claim 1, wherein the first curved surface has a first radius of curvature and the second curved surface has a second radius of curvature, the first radius of curvature being equal to the second radius of curvature.

5. 2. The non-pneumatic tire of claim 1, wherein the first curved surface has a first radius of curvature, the second curved surface has a second radius of curvature, and the lower ring outer surface has a third radius of curvature, and wherein each of the first radius of curvature and the second radius of curvature is different from the third radius of curvature.

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