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

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] 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 for an extended period of time and at a relatively high speed even after being punctured and partially or completely deflated. 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 selected 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, the non-pneumatic tire includes a lower ring provided with a plurality of scalar ribs. Each of the plurality of scalar ribs 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 composed 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 the opposite side of the first surface. Each of the first surface and the second surface extends between the first end and the second end. A foot portion is provided toward the first end of the spoke. The first surface of the spoke at the foot portion is a second curved surface. The second curved surface is attached to the first curved surface of one of the plurality of scalar ribs to connect the first end of the spoke 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 scalar ribs are formed on the lower ring. Each of the plurality of scalar ribs has a first curved surface. A plurality of spokes are formed, and each spoke has a first surface and a second surface facing the opposite side of the first surface. The first surface and the second surface 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 at the foot portion is a 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 at the foot portion to the first curved surface of one of the plurality of scalar ribs 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, the non-pneumatic tire includes a lower ring having a first radius of curvature. The lower ring is provided with a plurality of scallops. Each scallop has a first curved surface having a second radius of curvature. The upper ring is substantially coaxial with the lower ring. The support structure connects the lower ring to the upper ring. The support structure is composed 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 surface and the second surface extends between the first end and the second end. The spoke is provided with a foot portion toward the first end. The first surface of the spoke at the foot portion is a second curved surface having a third radius of curvature. Each of the first radius of curvature and the second radius of curvature is different from the third radius of curvature.

Brief Description of the Drawings

[0008] In the accompanying drawings, structures illustrating exemplary embodiments of the claimed invention are illustrated along with the detailed description provided below. Like elements are identified by 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.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 12a

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

DETAILED DESCRIPTION OF THE INVENTION

[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 definitions.

[0010] "Axial" and "axially" refer to a direction parallel to the rotational axis 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 rotational axis 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 general tire components are described by similar terms used in the following description, it should be understood that those skilled in the art will not consider any of the following terms to be purely interchangeable with another term used to describe general tire components, as the terms have somewhat different implications.

[0015] In this specification, directions are described 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 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 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 and toward the side 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 tire's equatorial plane than the "outer" element.

[0017] Figures 1 to 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 substantially 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 arrangement.

[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-stretchable materials. The layers may be formed from a sheet of material, a cord of material, a filament of material, or any other desired arrangement. In other alternative embodiments, the multi-layer tread band can include layers of stretchable materials such as elastomers. According to an exemplary embodiment, the tread band can include a pair of non-stretchable layers separated by a layer of stretchable material. In still 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 an interval 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 opposite 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 between those ends. 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 arrangement. In the illustrated embodiment, the foot portion 214 is substantially linear and its overall length (the dimension of the foot portion extending along the circumferential direction of the tire) and 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 still 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., a 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 arrangement. For example, attachment can be performed 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 to 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) or mechanism(s) may 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 r1. According to an exemplary embodiment, the first radius of curvature r1 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 r2. According to an exemplary embodiment, the second radius of curvature r2 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 straight. 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] The base plane p1 intersects the transition portion 224 and the second end 208 of the spoke 200 and functions as a reference for aspects regarding the various dimensions of the spoke 200. The angle between the base plane p1 and the second plane p2 that extends in a tangential direction with respect 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 +0 to 20 degrees. The distance 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 10 to 25 inches (25 to 63.5 cm). The distance 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 20 to 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 an exemplary embodiment, the distance d3 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 s1. The second ends 208 of the adjacent spokes 200 are separated from each other by a second spacing distance s2 (see also FIG. 5).

[0035] The non-pneumatic tire configured according to the above design parameters can provide a more robust assembly, particularly with respect to impact 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-impact events such as hitting a curb, pothole, or other obstacle or road defect during its lifespan. During a high-impact 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-impact event is the non-pneumatic tire 10 hitting a curb at low speed (e.g., a 6-inch (15-cm) curb at 5 miles per hour (8 km per hour)). Another example of a high-impact event is the non-pneumatic tire 10 hitting a stepped road defect at high speed (e.g., a 1-inch (2.5-cm) defect at 70 miles per hour (113 km per hour)). These are merely examples and do not limit the definition of a "high-impact 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 a non-limiting example, 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 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 more 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 is the cause of 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 the 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 undergo any other form of damage.

[0041] The maximum distance d3 between the knee portion 222 and the base plane p1 along the direction perpendicular to the base plane p1 affects the stiffness of the spokes and when contact between adjacent spokes 200 occurs. Increasing the distance d3 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 d3 decreases the stiffness of the spokes 200, and thus increases 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, physically moving each spoke 200 farther from the adjacent spokes 200, and thus causing contact between adjacent spokes 200 to occur relatively later. Additionally, decreasing the distance d3 increases the stiffness of the spokes 200, and thus decreases 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 along the direction parallel to the base plane p1 and the center of the first radius of curvature r1 of the knee portion 222 affects when contact with the adjacent spoke 200 occurs. When the distance d2 is a larger proportion of d1, as a result, contact between the adjacent spokes 200 will occur relatively early. When the distance d2 is a smaller proportion of d1, as a result, contact between the adjacent spokes 200 will occur relatively late.

[0043] The radius of curvature r1 of the knee portion 222 affects when contact with the adjacent spoke 200 occurs. Decreasing the radius of curvature r1 will result in contact between the adjacent spokes 200 occurring relatively late, and increasing the radius of curvature r1 will result in contact between the adjacent spokes 200 occurring relatively early. The spoke thickness t affects the rigidity of the spoke 200. Increasing the spoke thickness t increases the rigidity of the spoke 200, and decreasing the spoke thickness decreases the rigidity of the spoke 200.

[0044] Additionally, it has been found that the vertical rigidity of the tire is affected by the combination of the spoke thickness t and the distance d3. Increasing the distance d3 decreases the tire rigidity, and decreasing the distance d3 increases the tire rigidity. As a result, in order to meet the target value of the tire rigidity, it has been found that 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 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 that is 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. Additionally, 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 of 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 curved concavely 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 that are axially spaced from the first group of spokes. Further, a plurality of spokes in the first group of spokes are arranged to curve concavely with respect to a first circumferential direction of the tire, and a plurality of spokes in the second group of spokes are arranged to curve convexly 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 an alternative embodiment, 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 to 10, except for the differences described herein. Accordingly, similar features will be identified by similar numbers increased by a factor of "1000". In the spoke 200 shown in Figures 1 to 10, the second connecting portion 228 is linear. In comparison, the spoke 1200 of Figures 12 and 12a has a curved second connecting portion 1228 with a radius of curvature r3. Compared with the linear second connecting portion, the curved second connecting portion 1228 in the spoke 1200 of Figures 12 and 12a significantly improves the self-supporting behavior. According to one exemplary embodiment, the radius of curvature r3 is between 10 and 50 inches (25 to 127 cm).

[0050] In addition to the design parameters and resulting performance characteristic changes described above for the spoke 200 shown in Figures 1 to 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 flexure member 1216 flexure interact to affect the self-supporting performance. A smaller radius of curvature r3 of the curved second connecting portion 1228 reduces self-support and thus increases the stress during a high-impact event. A larger radius of curvature r3 of the curved second connecting portion 1228 increases self-support and thus reduces the stress during a high-impact event. However, this stress reduction only occurs up to a point. As the radius of curvature r3 increases (the limit being a radius of curvature r3 equal to infinity, which results in a linear second connecting portion), the effectiveness of self-support begins to decrease again.

[0051] The length l of the flexure member 1216 flexureaffects its ability to exert torque on the end of the spoke 1200. This torque acts to straighten the curved second connecting portion 1228 when the tire rolls under standard load or when subjected to a high-impact event. As a result, the curved second connecting portion 1228 having a smaller radius of curvature r3 is optimally aligned with the flexure member 1216 having a longer length l flexure and the curved second connecting portion 1228 having a larger radius of curvature r3 is found to be optimally aligned with the flexure member 1216 having a shorter length l flexure . The ability of the flexure member 1216 to exert torque on the spoke 1200 is affected by the length l flexure of the flexure member 1216 in addition to the stiffness of the material used to manufacture the flexure member 1216. As a result, when a softer material is used, a flexure member 1216 having a longer length l flexure is provided, and when a harder material is used, it is desirable to provide a flexure member 1216 having a shorter length l flexure .

[0052] 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, thus significantly reducing the stress on any single spoke within the non-pneumatic tire. This improves the durability of the non-pneumatic tire.

[0053] In the above-described embodiment, the leg portion 214 of the spoke 200 is initially substantially linear and joined to the curved outer surface 24 of the lower ring 20. This joining process conforms the leg portion 214 to the curvature of the outer surface 24. This arrangement results in a relatively simple manufacturing process for the spoke 200 and the lower ring 20, but may give rise to other potential design difficulties. For example, in an embodiment with a flat leg portion, the main applied force acting at the joint between the spoke and the ring is a tensile force. This tensile force may cause cleavage failure at the leading edge of the spoke. As another example, the rotational position of each spoke with respect to the lower ring and the upper ring cannot be adjusted without introducing undesirable prestress in the spoke.

[0054] Rotational adjustment of the spokes may be necessary to account for manufacturing tolerances. Ideally, all the spokes of the non-pneumatic tire are identical, including the dimensions of the various elements (e.g., the lengths of the leg portion, the first connecting portion, and the second connecting portion, and the angles between these elements (e.g., the angle between the leg portion and the first connecting portion, or the angle between the first connecting portion and the second connecting portion)). However, in practice, it is unlikely that all the spokes will be identical. Manufacturing guidelines approve variables within the formed features of the product, such as material thickness and tempering tolerances. Additionally, these manufacturing guidelines approve variables within the angular tolerances for bending, and one guideline suggests a tolerance of + / - 1 degree.

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

[0056] Figures 13 and 14 show the first spoke 200a, the second spoke 200b, and the third spoke 200c. In the first spoke 200a and the third spoke 200c, the angle θ between the foot portion 214 and the first connection portion 226 is 1 degree less than the specified design value, and in the second spoke 200b, this angle θ is 1 degree greater than the design value. FIG. 13 shows the spoke 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 before an external force is applied and before the flexure member 216 is attached to the upper ring 30). FIG. 14 shows the spoke 200 after the second end 208 of the spoke 20 is moved to the desired location and the flexure member 216 is attached to the upper ring 30. As shown in FIG. 13, when the angle between the foot portion 214 and the first connection portion 226 deviates from the specification by 1 degree, it can cause various problems, including the flexure member 216 being naturally placed on top of the upper ring 30 (second spoke 200b), or naturally placed below the upper ring 30 (first and third spokes 200a, 200c), and having an irregular spacing between adjacent spokes 200. Some of these problems can be corrected by pushing 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 spoke 200. Theoretically, each spoke 200 can be rotated about its first end 206 to correct these problems. However, in practice, due to the geometry between the flat foot portion 214 and the outer surface of the lower ring 20, such rotation is not possible.

[0057] FIG. 15 shows an alternative embodiment of a portion of a non-pneumatic tire having features that mitigate the above problems related to manufacturing tolerances. FIG. 16 shows a single spoke of the non-pneumatic tire of FIG. 15. The arrangements shown in FIGS. 15 and 16 are substantially similar to the arrangements shown in FIGS. 1 - 6, except for any differences described herein. Accordingly, similar features will be identified by similar numbers increased by a value of "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 composed of a plurality of spokes 2200 arranged in first and second spoke groups (not shown). The first spoke group and the second spoke group are offset and separated from each other in the axial direction of the non-pneumatic tire 2010.

[0059] Referring to FIG. 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 flexure 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 connection portion 2226 connects the transition portion 2224 to the knee portion 2222, and a second connection portion 2228 connects the knee portion 2222 to the second end 2208 of the spoke 2200.

[0060] On the outer surface 2024 of the lower ring 2020, a plurality of scallops 2025 equal in number to the total number of spokes 2200 within the support structure 2100 are provided (only a single scallop is shown in FIG. 15). The first surface 2210 of the spoke 2200 at the foot portion 2214 is curved and has a radius of curvature r equal to the radius of curvature r s of the corresponding scallop 2025 fpIt has. The scallops 2025 are spaced apart from each other 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 spoke group and the second spoke group, the scallop groups are also offset and separated from each other in the axial direction of the non-pneumatic tire 2010. The curved first surface 2210 of the spoke 2200 at the foot portion 2214 is joined to each scallop 2025 to attach the first end of the spoke 2200 to the lower ring 2020. The flexure member 2216 is joined to the upper ring so as to connect the second end 2208 of the spoke 2200 to the upper ring 2030. In an alternative embodiment, the foot portion or the flexure member may be attached to the scallop or the upper ring respectively using any desired arrangement. For example, the curved first surface of the spoke at the foot portion may be attached to each scallop using a nut and bolt arrangement, whereby the bolt extends into a through hole provided on the spoke and the lower ring, exposing a threaded portion for receiving the nut. This nut and bolt attachment can also be used to attach the flexure member to the upper ring. In other alternative embodiments, instead of separate scallop groups, each scallop may extend continuously across the lower ring in the axial direction, and the spokes of the first and second spoke groups may share each scallop.

[0061] The above arrangement helps to solve potential design problems associated with spoke embodiments having flat foot portions with respect 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 main applied force acting at the junction between the spokes 2200 and the lower ring 2020 is not the tension seen in flat foot portion embodiments, but rather a shear force. This change reduces the likelihood of a cleavage-type failure mode occurring at the connection between the spokes 2200 and the lower ring 2020. Further, the shear force acting at the junction between the spokes 2200 and the lower ring 2020 results in a substantially stronger failure mode for the junction in the case of the most commonly used adhesives.

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

[0063] Radius of curvature r of the foot portion 2214 fp and radius of curvature r of the scallop 2025 s have been found to should follow certain design principles in order to provide the above-described flexibility with respect to rotational position adjustment. According to one exemplary design principle, the radius of curvature r of the foot portion 2214 fp and radius of curvature r of the scallop 2025 s is different from the radius of curvature r of the outer surface of the lower ring 2020 lr

[0064] In the illustrated embodiment, both the curved second surface 2212 of the spoke 2200 and the scallop 2025 in the foot portion 2214 are convex with respect to the inner surface 2023 of the lower ring 2020, and the radius of curvature r in the foot portion 2214 fp ​and the radius of curvature r of the scallop 2025 s Both are constant and equal to each other. Additionally, the scallop 2025 is formed directly on the lower ring 2020. In an alternative embodiment, the second surface of the spoke may be convex with respect to the inner surface of the spoke, and the lower ring may be provided with corresponding bumps that are similarly convex with respect to the inner surface of the spoke. In other alternative embodiments, the radius of curvature of the foot portion or the radius of curvature of the scallop or bump may be variable or different from each other. In still other alternative embodiments, the scallop or bump may be formed on a sleeve fixed to the outer surface of the lower ring.

[0065] Figures 17 to 19 show another embodiment of the non-pneumatic tire 3010. The non-pneumatic tire 3010 of Figures 17 to 19 is substantially the same as the non-pneumatic tire 2010 of Figures 15 and 16, except for the differences described herein. Therefore, similar features will be identified by similar 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 composed of a plurality of spokes 3200 arranged in a first spoke group and a second spoke group (not shown). In the illustrated embodiment, for clarity, only a single row of spokes 3200 is shown, and the spokes 3200 extend across the entire axial width of the lower ring 3020. However, when two spoke groups 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 flexure 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 equal in number to the total number of spokes 3200 within the support structure 3100. The scallops 3024 are spaced apart from each other along the circumferential direction of the non-pneumatic tire 3010 and are arranged in first and second scallop groups (not shown). Similar to the separation between the first and second spoke groups, the scallop groups are also offset and spaced apart from each other in the axial direction of the non-pneumatic tire 3010. In an alternative embodiment, each scallop may extend continuously across the lower ring in the axial direction, and the spokes of the first and second spoke groups may share the respective scallops.

[0069] A mechanical fastening arrangement 3080 connects the foot portions 3214 of the spokes 3200 to the respective scallops 3205 to attach the first ends 3206 of the spokes 3200 to the lower ring 3020. An adhesive (not shown) can strengthen the connection by joining these components together. The adhesive can prevent wear between various components due to cyclic loading and can also prevent degradation (e.g., corrosion) resulting from exposure to environmental elements. The flexure member 3216 is attached to the upper ring 3030 so as 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 clamp plate 3082 and two socket head cap screws 3084. The clamp plate 3082 has a face 3086 having an axial width substantially the same as that of the foot portion 3214 and a radius of curvature substantially the same as the radius of curvature of the foot portion 3214. In an alternative embodiment, the axial width of the clamp plate may be greater or smaller than the axial width of the foot portion. In other alternative embodiments, the radius of curvature of the face of the clamp 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 socket head cap screw 3084 is positioned radially inward of the lower ring 3020 and the threaded portion of socket head cap screw 3084 passes 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) that allows the passage of socket head cap screw 3084. The through hole may be oversized or provided as a slot to allow adjustment of the position of the spoke 3200 relative to the lower ring 3020.

[0072] The threaded portion of socket head cap screw 3084 engages a female thread provided on the clamp plate 3082, and the clamp plate 3082 is positioned radially outward of the foot portion 3214. In an alternative embodiment, the orientation of the fastening arrangement may be reversed such that the head of the socket head cap screw is positioned radially outward of the clamp plate and the threaded portion engages a female thread provided on the lower ring. In other alternative embodiments, the socket head cap screw may be provided at any desired location, may be of any desired size, and may have more or fewer threads. In yet other alternative embodiments, the mechanical fastening arrangement, the lower ring, and / or the foot may be dimensioned and configured such that a second fastener does not extend through the lower ring or the clamp plate. Additionally, in yet other alternative embodiments, any desired mechanical fastening arrangement may be used (e.g., nuts and washers, studs or set screws together with rivets).

[0073] The mechanical fastening arrangement 3080 distributes the load over the axial width of the foot portion 3214 of the spoke 3200, thereby providing a more robust structure and also a more rigid connection. Further, the use of the clamp plate 3082 may facilitate the construction of the non-pneumatic tire 3010 by eliminating the need for a clamping arrangement when only an adhesive is used. Additionally, the mechanical fastening arrangement 3080 allows for the individual removal, servicing, and installation of a single spoke.

[0074] Figures 20 and 21 show another embodiment of the non-pneumatic tire 4010. The non-pneumatic tire 4010 of FIGS. 20 and 21 is substantially the same as the non-pneumatic tire 3010 of FIGS. 17 to 19, except for the differences described herein. Accordingly, similar features will be identified by similar 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 composed of a plurality of spokes 4200 arranged in a first spoke group and a second spoke group (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 flexure 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 connection portion 4226 connects the transition portion 4224 to the knee portion 4222, and a second connection 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 equal in number to the total number of spokes 4200 within the support structure 4100. The scallops 4024 are spaced apart from each other along the circumferential direction of the non-pneumatic tire 4010 and are arranged in first and second scallop groups (not shown). Similar to the separation between the first and second spoke groups, the scallop groups are also offset and spaced apart from each other in the axial direction of the non-pneumatic tire 4410. In an alternative embodiment, each scallop may extend continuously across the lower ring in the axial direction, and the spokes of the first and second spoke groups may share respective scallops.

[0078] A mechanical fastening arrangement 4080 connects the foot portions 4214 of the spokes 4200 to respective scallops 4205 to attach 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 thus will not be described further. An adhesive (not shown) can strengthen the connection by joining these components together. The adhesive can prevent wear between various components due to cyclic loading and can also prevent degradation (e.g., corrosion) resulting from exposure to environmental elements. A flexure member 4216 is attached to the upper ring 4030 so as to connect the second ends 4208 of the spokes 4200 to the upper ring 4030.

[0079] As described above, in the embodiments of FIGS. 1-19, for a single spoke, the knee portion and the transition portion are curved concavely in opposite directions. In comparison, according to the embodiments of FIGS. 20 and 21, the knee portion 4222 and the transition portion 4224 are curved concavely in the same direction. This arrangement can provide advantages regarding how the mechanical fastening arrangement 4080 and the adhesive (when used) receive loads and stresses. In particular, providing the knee portion 4222 and the transition portion 4224 to be curved concavely in the same direction can create a compression effect between the spoke 4200 and the lower ring 4020, which can reduce peeling problems, better disperse stresses, and thereby provide a more robust structure.

[0080] Individual embodiments and variations are shown and described in FIGS. 1-21, but the disclosed features are not limited to only the described embodiments. Instead, various features can be combined between embodiments as needed. For example, the arrangement of the curved foot portion of the spoke shown in FIGS. 15 and 16 may be combined with the curved connection portion of the spoke shown in FIGS. 12 and 12a.

[0081] The terms "includes" or "including" are intended to be inclusive, as is the term "comprising", when interpreted as such when used as a transitional word in a claim, to the extent that the terms are used in this specification or the claims. Further, in the context in which the term "or" is used (e.g., A or B), it is intended to mean "A or B, or both". When 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, the terms "in" or "into" are intended to additionally mean "on" or "onto", to the extent that the terms are used in this specification or the claims. Further, 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, to the extent that the term is used in this specification or the claims.

[0082] Although this 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 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. Thus, departures from such details may be made without departing from the spirit or scope of the general inventive concept of the applicant.

Claims

**Claim 1** A non-pneumatic tire, comprising a lower ring provided with a plurality of scallops, each of the plurality of scallops having a first curved surface, the lower ring; an upper ring substantially coaxial with the lower ring; a support structure connecting the lower ring to the upper ring, the support structure being composed of 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 having a first end connected to the lower ring; a second end connected to the upper ring; a first surface and a second surface facing the opposite side of the first surface, each of the first surface and the second surface extending between the first end and the second end, the first surface and the second surface; a foot portion provided toward the first end of the spoke, the first surface of the spoke at the foot portion being a second curved surface, the second curved surface being 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, the foot portion; a support structure; a non-pneumatic tire. **Claim 2** The non-pneumatic tire according to claim 1, wherein each of the first curved surface and the second curved surface is convex with respect to the inner surface of the lower ring. **Claim 3** The non-pneumatic tire according to claim 1, wherein the first curved surface has a first radius of curvature, 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. **Claim 4** The non-pneumatic tire according to 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 first radius of curvature is equal to the second radius of curvature. **Claim 5** The non-pneumatic tire according to claim 1, wherein the first curved surface has a first radius of curvature, the second curved surface has a second radius of curvature, the outer surface of the lower ring has a third radius of curvature, and each of the first radius of curvature and the second radius of curvature is different from the third radius of curvature. **Claim 6** The spokes of the first spoke group are curved in a concave shape with respect to the first circumferential direction of the tire, and the spokes of the second spoke group are curved in a convex shape with respect to the first circumferential direction of the tire. The non-pneumatic tire according to claim 1.

7. Each of the plurality of spokes has a knee portion located between the first end portion and the second end portion, and a transition portion located between the first end portion and the knee portion, and the knee portion and the transition portion are curved in a concave shape in opposite directions. The non-pneumatic tire according to claim 1.

8. Each of the plurality of spokes has a knee portion located between the first end portion and the second end portion, and a transition portion located between the first end portion and the knee portion, and the knee portion and the transition portion are curved in a concave shape in the same direction. The non-pneumatic tire according to claim 1.

9. 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 portion of the spoke to the upper ring. The non-pneumatic tire according to claim 1.

10. The non-pneumatic tire is arranged and configured such that when the non-pneumatic tire is in a first state, adjacent spokes among the plurality of spokes do not contact each other, and when the non-pneumatic tire is in a second state, the adjacent spokes among the plurality of spokes contact each other. The first state is when the tire rolls on a flat surface, and the second state is different from the first state. The non-pneumatic tire according to claim 1.

11. A method for manufacturing a non-pneumatic tire, comprising the steps of 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 scallops on the lower ring, each of the plurality of scallops having a first curved surface. A step of forming a plurality of spokes, each spoke having a first surface and a second surface facing the opposite side of the first surface, the first surface and the second surface each extending between a first end and a second end, the step of forming the plurality of spokes including providing a foot portion toward the first end of the spoke, the first surface of the spoke at the foot portion being a second curved surface, the forming step; A step of connecting the lower ring to the upper ring using the first spoke group and the second spoke group, the step of connecting the lower ring to the upper ring including attaching the second curved surface of the spoke at 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, the connecting step, including a method of manufacturing a non-pneumatic tire.

12. The forming of the plurality of scallops includes providing the first curved surface as a first convex surface with respect to the inner surface of the lower ring, and the forming of the plurality of spokes includes providing the first surface of the spoke at the foot portion as a second convex surface with respect to the inner surface of the lower ring, the method of manufacturing a non-pneumatic tire according to claim 11.

13. The forming of the plurality of scallops includes providing the first curved surface having a first radius of curvature, and the forming of the plurality of spokes includes providing the first surface of the spoke at the foot portion having a second radius of curvature, the first radius of curvature and the second radius of curvature being different from a third radius of curvature of the outer surface of the lower ring, the method of manufacturing a non-pneumatic tire according to claim 11.

14. The arranging of the plurality of spokes into the first spoke group and the second spoke group includes 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 of manufacturing a non-pneumatic tire according to claim 11.

15. further comprising the steps of attaching a flexure member to each spoke and attaching the flexure to the upper ring, wherein attaching the flexure member to the upper ring comprises connecting the second end of the spoke to the upper ring while connecting the lower ring to the upper ring, a method of manufacturing a non-pneumatic tire according to claim 11.

Images