Mounting arrangement of self-supporting spoke structure for non-pneumatic tires

Abstract

This invention relates to a non-pneumatic tire having a support structure with spokes designed to come into contact with each other in the event of a high-impact event. [Solution] The non-pneumatic tire 10 includes a lower ring 20 having a first diameter and an upper ring 30 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 consists of a plurality of spokes 200 and a plurality of boots corresponding to the plurality of spokes. The support structure is arranged and configured such that adjacent spokes among the plurality of spokes come into contact with each other in the event of a high impact event.

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 allow 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 a long 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 withstand high-impact events such as collisions with curbs, potholes, or other obstacles or road defects.

Summary of the Invention

[0005] In one embodiment, a non-pneumatic tire includes a lower ring having a first diameter and an upper ring having a second diameter. The upper ring is substantially coaxial with the lower ring. A support structure connects the lower ring to the upper ring. The support structure is composed of a plurality of spokes. The plurality of spokes are arranged in a first group of spokes and a second group of spokes axially spaced apart from the first group of spokes. Each of the plurality of spokes includes a first end connected to the lower ring, a second end connected to the upper ring, and a boot at the first end. The boot has a floor portion. The floor portion is attached to the lower ring so as 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 the step of providing a lower ring having a first diameter and an upper ring having a second diameter greater 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 spoke extends between a first end and a second end. A plurality of boots are formed. Each of the plurality of boots has a second curved surface. The plurality of boots are attached to each of the plurality of spokes at the first end. The plurality of spokes are arranged as a first group of spokes and a second group of spokes axially spaced apart from the first group of spokes. The method further includes the step of connecting the lower ring to the upper ring using the first group of spokes and the second group of spokes. The step of connecting the lower ring to the upper ring includes attaching the second curved surface of the boot to the first curved surface of one of the multiple scallops, connecting the first end of the spoke to the lower ring, and connecting the second end of the spoke to the upper ring.

[0007] In another embodiment, a 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. An upper ring is 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. Each spoke extends between a first end and a second end. The first end is provided with a boot. The boot has 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 drawing]

[0008] The attached drawings illustrate structures illustrating exemplary embodiments of the claimed invention, along with the detailed description provided below. Similar elements are identified by the same reference numeral. It should be understood that elements shown as single components may be replaced by multiple components, and elements shown as multiple components may be replaced by single components. The drawings are not to exact scale, and the proportions of certain elements may be exaggerated for illustrative purposes. [Figure 1] Figure 1 is a side view of one embodiment of a non-pneumatic tire. [Figure 2] Figure 2 is another side view of the non-pneumatic tire shown in Figure 1. [Figure 3] Figure 3 is a cross-sectional view along line 3-3 in Figure 1. [Figure 4] Figure 4 is a detailed view of area A in Figure 1. [Figure 5] Figure 5 is a detailed view of region A in Figure 1, with some features removed for clarity. [Figure 6] Figure 6 is a detailed view of a single spoke used in the non-pneumatic tire shown in Figure 1. [Figure 7] Figure 7 is a partial side view of the non-pneumatic tire shown in Figure 1 when the tire is on a flat surface and bearing a standard load. [Figure 8]Figure 8 is a partial side view of the non-pneumatic tire from Figure 1 when the tire is on a flat surface and bearing a standard load, with some features removed for clarity. [Figure 9] Figure 9 is a partial side view of the non-pneumatic tire shown in Figure 1 when the tire is on a non-flat surface. [Figure 10] Figure 10 is a partial side view of the non-pneumatic tire from Figure 1 when the tire is on a non-flat surface, with some features removed for clarity. [Figure 11] Figure 11 is a flowchart showing the method for manufacturing the non-pneumatic tire shown in Figure 1. [Figure 12] Figure 12 shows another embodiment of spokes for a non-pneumatic tire. [Figure 12a] Figure 12a is an end view of the spoke in Figure 12 along II. [Figure 13] Figure 13 is a side view of a non-pneumatic tire showing the effect of manufacturing tolerances on spokes before the second end of the spoke is attached to the upper ring. [Figure 14] Figure 14 is a side view of the non-pneumatic tire from Figure 13 after the second end of the spokes has been attached to the upper ring. [Figure 15] Figure 15 is a partial view of another embodiment of a non-pneumatic tire. [Figure 16] Figure 16 is a detailed view of a single spoke used in the non-pneumatic tire shown in Figure 15. [Figure 17] Figure 17 is a diagram that follows line 17-17 of Figure 15. [Figure 18] Figure 18 is a partial view of another embodiment of a non-pneumatic tire. [Figure 19] Figure 19 is a perspective view of the end cap. [Figure 20] Figure 20 is a partial side view of another embodiment of a non-pneumatic tire. [Figure 21] Figure 21 is a partial perspective view of the non-pneumatic tire shown in Figure 20. [Figure 22]FIG. 22 is another partial perspective view of the non-pneumatic tire of FIG. 20.

BEST MODE FOR CARRYING OUT 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 rotation axis of the tire.

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

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

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

[0014] Common tire components are described by similar terms used in the following description. However, it should be understood that since the terms have somewhat different implications, those skilled in the art will not consider any of the following terms to be purely interchangeable with another term used to describe common tire components.

[0015] In this specification, directions are described with respect to the tire's axis of rotation. The terms “upward” and “towards” refer to the general direction toward the tire's tread, while “downward” and “towards” refer to the general direction toward the tire's axis of rotation. Therefore, when relative directional terms such as “upper” and “lower” or “top” and “bottom” are used in relation to elements, the “upper” or “top” element is spaced further away from the tread than the “lower” or “bottom” element. Additionally, when relative directional terms such as “up” or “down” are used in relation to elements, an element “above” another element is closer to the tread than the other element.

[0016] The terms "inner" and "inward" refer to the general direction toward the tire's equatorial plane, while "outer" and "outward" refer to the general direction toward the tire's side, away from the tire's equatorial plane. Therefore, when relative directional terms such as "internal" and "external" are used in relation to elements, "internal" elements are spaced further away from the tire's equatorial plane than "external" elements.

[0017] Figures 1 to 5 illustrate one embodiment of a non-pneumatic tire 10. The non-pneumatic tire 10 is merely an illustrative 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 with 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 may be made of a polymer material, an elastomer material, a composite material composed of a metal, a glass fiber or carbon fiber reinforced polymer, 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 larger diameter than 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 may be made from a polymer material, an elastomer material, a composite material composed of a polymer reinforced with metal, glass or carbon fiber, 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 may be attached to the upper ring 30 by adhesive, mechanically, or in any other desired arrangement.

[0019] As shown in Figure 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 from the same material or from different materials. The tread layer 74 may be made from 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 multilayer band. Such a multilayer tread band may include one or more layers of substantially non-stretchable material. The layers may be formed from sheets of material, cords of material, filaments of material, or any other desired arrangement. In another alternative embodiment, the multilayer tread band may include layers of stretchable material such as elastomer. According to one exemplary embodiment, the tread band may include a pair of non-stretchable layers separated by layers of stretchable material. In yet another alternative embodiment, the tread band may include bands referred to as shear bands, shear elements, or thin annular high-strength band elements.

[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 spoke groups, including a first spoke group 202 and a second spoke group 204 axially spaced apart from the first spoke group 202. In an alternative embodiment, the support structure may include three or more axially spaced spoke groups.

[0022] As shown in Figure 3, the first spoke group 202 and the second spoke group 204 are spaced apart from each other in the axial direction. In an alternative embodiment, the spacing between the first spoke group and the second spoke group may be greater or smaller, or the first and second spoke groups may be arranged without any spacing between them. Viewed from the viewpoint shown in Figure 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 spokes 200 of the first and second spoke groups 202 and 204 have the same configuration. Therefore, the description of the spokes 200 will be made with reference to a single spoke 200 shown in Figure 6. The spokes 200 may be made from metals such as steel or aluminum, polymers such as polyester or nylon, composite materials such as glass fiber or carbon fiber reinforced polymer, or any other desired material or combination of materials. The spokes 200 may be provided with reinforcing members (not shown).

[0024] The spoke 200 extends between a first end 206 and a second end 208 and has a substantially rectangular cross-section including a first surface 210 and a second surface 212 facing the opposite side of 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 spoke thickness may vary between the first and second ends. For example, the spoke may have relatively thicker portions at the first and second ends and a relatively thinner portion between those ends. In another alternative embodiment, 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] An integral foot portion 214 is provided toward the first end 206 of the spoke 200. The first surface 210 of the spoke 200 in the foot portion 214 is attached to the outer surface 24 of the lower ring 20 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, adhesive, mechanical fasteners (e.g., bolts, rivets), keys / keyways, or any other desired arrangement. In the illustrated embodiment, the foot portion 214 is substantially linear, and its entire length (the dimension of the foot portion extending along the circumferential direction of the tire) and entire 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 another alternative embodiment, 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 another alternative embodiment, only a portion of the leg portion, or several separate portions, may be attached to the outer surface of the lower ring. In yet another alternative embodiment, the leg portion may be attached below the outer surface of the lower ring, or the spokes may extend through the lower ring so that the leg portion can be attached to the inner surface of the lower ring.

[0026] A flexible member 216 is provided at the second end 208 of the spoke 200. The flexible member 216 has a width that extends along the axial direction of the tire. The flexible member 216 may be manufactured 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 member 216 is provided as a rectangular parallelepiped and positioned so that its end aligns with the second end 208 of the spoke 200. In other alternative embodiments, the flexible member may be positioned so that its end recedes from the second end of the spoke, or so that its end extends beyond the second end of the spoke. In yet another alternative embodiment, the flexible member may be replaced by a mechanical pin joint (i.e., a hinge).

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

[0028] The flexible 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 flexible member 216, the connection provided by the foot portion 214 at the first end 206 of the spoke 200 is more rigid.

[0029] In alternative embodiments, the flexible member may have a shape or configuration different from that specifically illustrated and described. In other alternative embodiments, additional structures or mechanisms may complement the flexible member for attaching the second end of the spoke to the upper ring. In yet another alternative embodiment, the flexible 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 to the inner surface of the upper ring, or the spoke may extend through the upper ring so that its second end can be attached to the outer surface of the upper ring.

[0030] The spoke 200 includes a knee portion 222 between a first end 206 and a 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 2 to 6 inches (5 to 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 portion 206. The transition portion 224 has a second radius of curvature r2. According to one exemplary embodiment, the second radius of curvature r2 is 0 to 2 inches (0 to 5 cm). When attached to the upper and lower rings 20, 30, the transition portion 224 is convex relative to the lower ring 20. Thus, with respect to a single spoke 200, the knee portion 222 and the transition portion 224 are concave in opposite directions. In an alternative embodiment, the knee portion and the transition portion are 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 connecting portion 226 connects the transition portion 224 to the knee portion 222, and the second connecting 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 connecting portions 226, 228 are straight. In alternative embodiments, the first or second connecting portion may be curved or 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 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 the various dimensions of the spoke 200. The angle between the base plane p1 and the second plane p2 extending tangentially to the outer surface 24 of the lower ring 20 at the transition portion 224 is α. According to one exemplary embodiment, the angle α is 5 to 20 degrees. The distance between the transition portion 224 and the second end 208 of the spoke 200 along the direction parallel to the base plane p1 is d1. According to one exemplary embodiment, the distance d1 is 10 to 15 inches (25 to 38 cm). The distance between the center of the transition portion 224 along the direction parallel to the base plane p1 and the center of the first curvature r1 of the knee portion 222 is d2. According to one exemplary embodiment, the value of the distance d2 is 40 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 one exemplary embodiment, the distance d3 is 2 to 4 inches (5 to 10 cm).

[0034] Referring to Figure 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.

[0035] A non-pneumatic tire configured according to the design parameters described above can provide a more robust assembly, particularly in terms of impact performance. Figures 7 and 8 show an exemplary tire in a first state. As shown in Figures 7 and 8, according to a non-limiting example, in the first state, the tire 10 rolls on a flat surface while bearing a load (i.e., normal operation), and the non-pneumatic tire 10 deforms, but adjacent spokes 200 do not come into contact with 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 during its lifespan, such as hitting curbs, potholes, or other obstacles or road defects. During high-impact events, the non-pneumatic tire 10 may deform to a significantly higher level than the deformation that occurs during normal operation.

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

[0038] The non-pneumatic tire 10 responds to high-impact events by deforming so that adjacent spokes 200 come into contact with each other. Surprisingly, it was found that contact between adjacent spokes 200 during high-impact events significantly reduces the stress on individual spokes 200 compared to a non-pneumatic tire where the spokes do not come into contact with each other during high-impact events. This reduction in stress on individual spokes 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, and therefore reduce 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 spokes 200 in contact with each other are located adjacent to the obstacle or road defect that caused 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 another alternative embodiment, the adjacent spokes that contact each other simultaneously may be located at any position along the circumferential direction of the tire (i.e., they may be 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 modified to provide the non-pneumatic tire 10 with desired performance characteristics. Preferably, these design parameters are selected so that contact occurs between adjacent spokes 200 before the spokes 200 begin to yield or begin to 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 and when contact occurs between adjacent spokes 200. Increasing the distance d3 physically moves each spoke 200 closer to its neighbors, 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 under a given load, which increases the likelihood of contact between adjacent spokes 200. Decreasing the distance d3 has the opposite effect, moving each spoke 200 further away from its neighbors, thus causing contact between adjacent spokes 200 to occur relatively later. Additionally, decreasing the distance d3 increases the stiffness of the spokes 200, thus decreasing the amount of deflection under a given load, which reduces 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 between adjacent spokes 200. When the distance d2 is a larger proportion of d1, contact between adjacent spokes 200 occurs relatively sooner. When the distance d2 is a smaller proportion of d1, contact between adjacent spokes 200 occurs relatively later.

[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 occurring relatively late between adjacent spokes 200, while increasing the radius of curvature r1 results in contact occurring relatively early between adjacent spokes 200. The spoke thickness t affects the stiffness of the spoke 200. Increasing the spoke thickness t increases the stiffness of the spoke 200, while decreasing the spoke thickness decreases the stiffness of the spoke 200.

[0044] Additionally, it has been found that the vertical stiffness of a tire is affected by the combination of spoke thickness t and distance d3. Increasing the distance d3 decreases tire stiffness, and decreasing the distance d3 increases tire stiffness. As a result, it was found that to meet the target value of tire stiffness, 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] Figure 11 is a flowchart illustrating an exemplary method for manufacturing a non-pneumatic tire. In 1010, a lower ring and an upper ring are provided. The lower ring and upper ring, having a first diameter, have a second diameter that is larger than the first diameter. In 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., high-pressure resin transfer molding). 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] In 1030, a flexible member is attached to the spoke. In 1040, the spoke is arranged in a first group of spokes and a second group of spokes spaced axially apart from the first group of spokes. Furthermore, a plurality of spokes of the first group of spokes are arranged to curve concavely with respect to the first circumferential direction of the tire, and a plurality of spokes of the second group of spokes are arranged to curve convexly with respect to the first circumferential direction of the tire.

[0047] In 1040, the lower ring is connected to the upper ring using a first group of spokes and a second group of spokes. Each leg of a spoke is attached to the lower ring so as to connect the first end of each spoke to the lower ring. The flex member is attached to the upper ring so as to connect the second end of each spoke to the upper ring.

[0048] In alternative embodiments, the steps described above 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 in Figures 12 and 12a is substantially the same as the spoke 200 in Figures 1 to 10, except for the differences described herein. Thus, similar features are identified by similar numbers that are increased by "1000". In the spoke 200 shown in Figures 1 to 10, the second connecting portion 228 is straight. In comparison, the spoke 1200 in Figures 12 and 12a has a curved second connecting portion 1228 having a radius of curvature r3. Compared with a straight 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 10 to 50 inches (25 to 127 cm).

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

[0051] The width wflexure of the flexible member 1216 affects its ability to exert torque on the ends of the spokes 1200. This torque acts to straighten the curved second connecting portion 1228 when the tire rolls under a standard load or when subjected to a high-impact event. As a result, it was found that a curved second connecting portion 1228 with a smaller radius of curvature r3 is optimally matched with a flexible member 1216 with a larger width wflexure, and a curved second connecting portion 1228 with a larger radius of curvature r3 is optimally matched with a flexible member 1216 with a smaller width wflexure. The ability of the flexible member 1216 to exert torque on the spokes 1200 is influenced by the stiffness of the material used to manufacture the flexible member 1216, in addition to the width wflexure of the flexible member 1216. As a result, it is desirable to provide a flexible member 1216 with a wider wflexure when a softer material is used, and a flexible member 1216 with a narrower wflexure when a harder material is used.

[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 high-impact events. The contact between adjacent spokes results in multiple 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 embodiments described above, the foot portion 214 of the spoke 200 is initially substantially straight and joined to the curved outer surface 24 of the lower ring 20. This joining process conforms the foot portion 214 to the curvature of the outer surface 24. While this arrangement results in a relatively simple manufacturing process for the spoke 200 and the lower ring 20, it can give rise to other potential design challenges. For example, in embodiments with flat foot portions, the primary applied force acting on the joint between the spoke and the ring is a tensile force. This tensile force can cause splitting 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 to the spoke.

[0054] Spoke rotation adjustment may be necessary to account for manufacturing tolerances. Ideally, all spokes of a non-pneumatic tire should be identical in various dimensions (e.g., the lengths of the foot portion, first joint portion, and second joint portion, as well as the angles between these elements (e.g., the angle between the foot portion and the first joint portion, or between the first joint portion and the second joint portion)). However, in practice, it is unlikely that all spokes will be identical. Manufacturing guidelines approve variables within the formed characteristics of the product, such as material thickness and temper tolerances. Additionally, these manufacturing guidelines approve variables within the angular tolerance for bending, with one guideline suggesting a tolerance of + / - 1 degree.

[0055] Figures 13 and 14 illustrate how this + / - 1 degree tolerance may affect the support structure of a non-pneumatic tire. The non-pneumatic tires in Figures 13 and 14 are constructed according to the embodiments of the non-pneumatic tires in Figures 1 to 6. Therefore, similar features will be identified by similar figures.

[0056] Figures 13 and 14 show the first spoke 200a, the second spoke 200b, and the third spoke 200c. For 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 smaller than the specified design value, while for the second spoke 200b, this angle θ is 1 degree larger than the design value. Figure 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 stationary position (i.e., the position of the second end 208 of the spoke 200 before any external force is applied and the flexible member 216 is attached to the upper ring 30). Figure 14 shows the spokes 200 after the second end 208 of the spoke 200 has been moved to the desired position and the flexible member 216 has been attached to the upper ring 30. As shown in Figure 13, a deviation of just 1 degree in the angle between the foot portion 214 and the first connecting portion 226 from the specification can cause a variety of problems, including the flexible member 216 naturally resting on 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 can be corrected by pushing the second end 208 of each spoke 200 into a desired position, as shown in Figure 14, but doing so introduces undesirable prestress to the spoke 200. Theoretically, each spoke 200 could be rotated around its first end 206 to correct these problems. However, in practice, such rotation is impossible due to the geometric shape between the flat foot portion 214 and the outer surface of the lower ring 20.

[0057] Figure 15 shows some alternative embodiments of a non-pneumatic tire having features that mitigate the above-mentioned problems with manufacturing tolerances. Figures 16 and 17 show a single spoke of the non-pneumatic tire of Figure 15. The arrangements shown in Figures 15 to 17 are substantially similar to those shown in Figures 1 to 6, except for any differences described herein. Thus, similar features will be identified by similar numbers increased by the 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 consists of a plurality of spokes 2200 (only a single spoke is shown) arranged in a first spoke and a second group of spokes (not shown). The first group of spokes and the second group of spokes are offset and spaced apart from each other in the axial direction of the non-pneumatic tire 2010.

[0059] 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 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 first connecting portion 2226 connects the first end 2206 to the knee portion 2222. A second connecting portion 2228 connects the knee portion 2222 to the second end 2208 of the spoke 2200. Unlike the spokes shown in the embodiments of Figures 1 to 6, the spokes shown in the embodiments of Figures 15 to 17 do not include a transition portion or foot portion.

[0060] The boot 2215 is attached to the first end 2206 of the spoke 2200. The boot 2215 may be made of steel, aluminum, titanium, magnesium, composite material (e.g., aluminum metal matrix, carbon fiber, reinforced plastic), or any other desired material, and may be attached to the spoke 2200 using adhesive, mechanical fasteners, a combination of adhesive and mechanical fasteners, welding, or any other desired arrangement. The boot 2215 extends between the first edge 2327 and the second edge 2329. The distance between the first edge 2327 and the second edge 2329 defines the boot width. As used herein, “width” refers to the dimension of a component that extends along the axial direction of the non-pneumatic tire 2010. In the illustrated embodiment, the width of the boot 2215, the width of the spoke 2200, and the width of the lower ring 2020 are all equal to one another. In an alternative embodiment, the widths of the boot, spokes, and lower ring may be increased or decreased such that the width of one of these elements is greater or less than that of another of the elements.

[0061] The boot 2215 includes a first side 2217 and a second side 2219. The first side 2217 includes a first straight roof section 2221. The second side 2219 includes a second arched roof section 2227. The first roof section 2221 and the second roof section 2227 intersect at a vertex 2229. The spokes 2200 enter the boot 2215 through openings 2231 provided in the second arched roof section 2227. A first wall section 2233 extends obtusely from the first roof section 2221, and a second wall section 2235 extends obtusely from the second roof section 2221. Both the first wall section 2233 and the second wall section 2235 are straight and extend parallel to each other. The floor portion 2237 extends between the first wall portion 2233 and the second wall portion 2235. The first end 2206 of the spoke 2200 is spaced apart from the floor portion 2237 when the spoke 2200 is received within the boot 2215. The boot 2215 may provide a more rigid mounting than the spoke embodiment without a boot. The design of the boot and the orientation of the spokes relative to the boot can be modified to provide a non-pneumatic tire with desired performance characteristics.

[0062] 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. The floor portion 2237 of the boot 2215 is curved and has a radius of curvature rfp equal to the radius of curvature rs of the corresponding scallop 2025. 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 groups of scallops (not shown). Similar to the separation between the first group of spokes and the second group of spokes, the groups of scallops are also offset and spaced apart from each other in the axial direction of the non-pneumatic tire 2010. The floor portion 2237 of the boot 2215 is joined to each scallop 2025 to attach the first end of the spokes 2200 to the lower ring 2020. The flexible member 2216 is joined to the upper ring 2030 so as to connect the second end 2208 of the spoke 2200 to the upper ring 2030. In an alternative embodiment, the boot or flexible member may be attached to the scallop or upper ring, respectively, using any desired arrangement.

[0063] The above arrangement helps to solve potential design problems associated with the flat-footed spoke embodiment regarding spoke manufacturing tolerances. By providing the non-pneumatic tire 2010 with spokes 2200 having boots 2215 with curved floor portions 2237 and corresponding curved scallops 2205, the primary applied force acting on the joint between the boot 2215 and the lower ring 20 becomes a shear force rather than the tensile force seen in the flat-footed embodiment. This change reduces the likelihood of a splitting failure mode occurring at the joint between spokes 2200 and the lower ring 2020. Furthermore, the shear force acting on the joint between the boot 2215 and the lower ring 2020 leads to a substantially stronger failure mode at the joint, in the case of the most commonly used adhesives.

[0064] Additionally, the curved floor portion 2237 and scallop 2025 of the boot 2215 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 in the case of a flat foot portion embodiment. These curved surfaces also allow a constant adhesive gap to be maintained between the boot 2215 and the scallop 2025 during such adjustment of rotational position.

[0065] It has been found that the radius of curvature rfp of the floor portion 2237 and the radius of curvature rs of the scallop 2025 should follow certain design principles in order to provide the aforementioned flexibility with respect to rotational position adjustment. According to one exemplary design principle, the radius of curvature rfp of the floor portion 2237 and the radius of curvature rs of the scallop 2025 are different from the radius of curvature rlr of the outer surface 2024 of the lower ring 2020.

[0066] In the illustrated embodiment, both the floor portion 2237 and the scallop 2025 of the boot 2215 are convex with respect to the inner surface 2023 of the lower ring 2020, and the radius of curvature rfp of the floor portion 2237 and the radius of curvature rs of the scallop 2025 are both constant and equal to each other. Additionally, the scallop 2025 is formed directly on the lower ring 2020. In an alternative embodiment, the floor portion of the boot may be convex with respect to the inner surface of the spokes, and the lower ring may be provided with corresponding bumps that are similarly convex with respect to the inner surface of the spokes. In yet another alternative embodiment, the radius of curvature of the floor portion or the radius of curvature of the scallop or bump may be variable or different from each other. In yet another alternative embodiment, the scallop or bump may be formed on a sleeve fixed to the outer surface of the lower ring.

[0067] Additionally, it has been found that boots can be used without scallops on the inner ring. In such an arrangement, the floor portion of the boot has a shape that complements the shape of the outer surface of the lower ring. According to one non-limiting example where scallops are not used, the floor portion of the boot has substantially the same radius of curvature as the radius of curvature of the outer surface of the lower ring. Furthermore, it has been found that scallops on the lower ring may have a shape other than curved. According to one non-limiting example, scallops may be provided as a flat portion on the outer surface of the lower ring. In this arrangement, the floor portion of the boot is flat to complement the flat portion on the lower ring.

[0068] Figure 18 shows a modified version of the boot 3215 for a non-pneumatic tire. The boot 3215 in Figure 18 is substantially similar to the boot 2215 shown on the non-pneumatic tire 2010 in Figures 15-17, except for the differences described herein. Thus, similar features are identified by similar numbers that are increased by "1000".

[0069] The boot 3215 includes a first side 3217 and a second side 3219. The first side 3217 includes a first straight roof section 3221. The second side 3219 includes a second stepped roof section 3227. The first roof section 3221 and the second roof section 3227 intersect at a vertex 3229. The spokes 3200 enter the boot through an opening 3231 provided in the second roof section 3227. The opening 3231 extends across the entire width of the boot 6548 and separates the second roof section 3227 into a first step 3227a and a second step 3227b. A straight wall section 3235 extends substantially perpendicularly from the second step 3227b. The wall section 3235 extends substantially parallel to the first roof section 3221. A straight ceiling section 3239 extends from the wall section 3235 at an arc-shaped angle. Both the straight ceiling section 3239 and the wall section 3235 define a substantially V-shaped notch. A floor section 3237 extends between the first roof section 3221 and the ceiling section 3239. The floor section 3237 has a radius of curvature rfp equal to the radius of curvature rs of the corresponding scallop 3025 provided on the outer surface 3024 of the lower ring 3020.

[0070] The specific arrangement of the boot 3215 may allow for adjustment of the local stiffness of the boot 3215, thereby reducing peak stress in the adhesive or other fastening arrangement. This reduction in peak stress may be provided by a V-shaped notch defined by the linear ceiling portion 3239 and the wall portion 3235. The design of the boot and the orientation of the spokes relative to the boot can be modified to provide a non-pneumatic tire with specific desired performance characteristics. For example, increasing the size of the V-shaped notch may decrease the stiffness of the boot, while decreasing the size of the notch may increase the stiffness of the boot. As another example, changing where the spokes enter the boot may also change the stress in the boot and the adhesive or other fastening arrangement.

[0071] Figure 19 shows an end cap 5000 that can be used with a spoke 5002 having a boot 5004. The end cap 5000 may be provided to limit the "overflow" of adhesive during the bonding process between the boot and the lower ring 5003. Additionally, the end cap may act as a structural member to reinforce the boot 5004.

[0072] The end cap 5000 may be manufactured from metal, composite material, plastic, rubber, polymer, or any other desired material or combination of materials. The end cap 5000 includes a boot mating surface 5006 and an externally facing surface 5008. The boot mating surface 5006 is attached to the boot 5004 to secure the end cap 5002 to the boot 5004. This attachment can be achieved using adhesive, mechanical fasteners, a combination of adhesive and mechanical fasteners, or any other desired fastening arrangement. The externally facing surface 5008 may be plain or may have functional or decorative features (e.g., a company logo).

[0073] The end cap 5000 includes a first roof portion 5010 and a second roof portion 5012 that intersect at the apex 5014. A first wall portion 5016 extends from the first roof portion 5010, and a second wall portion 5018 extends from the second roof portion 5012. A floor portion 5020 extends between the first wall portion 5016 and the second wall portion 5018. In the illustrated embodiment, the shape of the end cap 5000 is substantially the same as the shape of the boot 5004 to which the end cap 5000 is attached. In an alternative embodiment, the end cap 5000 may have any desired shape (i.e., a shape different from the shape of the boot).

[0074] Figures 20–22 show another embodiment of the boot 4215 for non-pneumatic tires. The boot 4215 is similar to the boot 2215 shown in Figures 15–17 for non-pneumatic tires, except for the differences described herein. Thus, similar features will be identified by similar numbers increased by "2000".

[0075] The boot 4215 includes a first part 4217 and a second part 4219. The first part 4217 and the second part 4219 are separate and distinct components. The first part 4217 and the second part 4219 define a gap 4231 for receiving the spoke 4200. When received in this manner, the spoke 4200 is sandwiched between the first part 4217 and the second part 4219.

[0076] The first component 4217 includes a straight roof portion 4221 and a floor portion 4237. The floor portion 4237 has a radius of curvature rfp substantially equal to the radius of curvature rs of the corresponding scallop 4025 provided on the outer surface 4024 of the lower ring 4020. Each first component 4217 is connected to the lower ring 4020 by two first fasteners 4270. An adhesive (not shown) may be used to reinforce the connection between the first component 4217 and the lower ring 4020 by joining the floor portion 4237 to the scallop 4025. The adhesive can prevent wear between the various components due to periodic loading and can also prevent deterioration (e.g., corrosion) resulting from exposure to environmental elements. In an alternative embodiment, the first component may have any desired shape (e.g., a curved roof portion).

[0077] In the illustrated embodiment, each first fastener 4270 is provided as an assembly including a threaded rod, a washer, and a nut. The threaded rod engages with a female thread provided on the first part 4217. In an alternative embodiment, each first fastener may have any desired arrangement (e.g., a socket head cap screw, two nuts provided at both ends of the threaded rod rather than on the female thread on the first part, and a screw or flanged stud that passes through the first part and screws into a female thread provided on the lower ring). In yet another alternative embodiment, each of the first fasteners may be provided with a different arrangement (e.g., a threaded rod, washer, and nut for one of the first fasteners, and a socket head cap screw for the other of the first fasteners). In yet another alternative embodiment, there may be more or fewer first fasteners.

[0078] The first fastener 4270 extends through the lower ring 4020, the floor portion 4237, and the straight roof portion 4221. When positioned in this manner, the floor portion 4237 is attached to the lower ring 4020. In alternative embodiments, the first fastener, the lower ring, and / or the first component may be sized and configured such that the first fastener does not extend through the floor portion or the straight roof portion. For example, the first fastener may be made shorter so that it terminates within the first component rather than extending through the straight roof portion.

[0079] The second part 4219 is attached to the first part 4217 by a plurality of second fasteners 4272. The second fasteners 4272 also attach the spokes 4200 to the boot 4215. In the illustrated embodiment, the second fasteners 4272 are eight socket head cap screws aligned with each other. The threads of the socket head cap screws engage with the female threads provided on the second part 4219. In an alternative embodiment, the second fasteners may have any desired arrangement (e.g., nuts that engage with the threads of the socket head cap screws rather than the female threads on the second part). In yet another alternative embodiment, there may be more or fewer second fasteners. And in yet another alternative embodiment, the second fasteners may be offset from each other.

[0080] The second fastener 4272 extends through the straight roof portion 4221, the spokes 4200, and the wall portion 4235 of the first part 4217. With this arrangement, the spokes 4200 are effectively clamped between the first part 4217 and the second part 4219. An adhesive (not shown) can be used to reinforce the connection between the first part 4217 and the second part 4219 and the spokes 4200 by joining these components together. The adhesive can prevent wear between the various components due to periodic loading and can also prevent deterioration (e.g., corrosion) resulting from exposure to environmental elements. In alternative embodiments, the second fastener, the second part, the spokes, and the first part may be sized and configured such that the second fastener does not extend through the wall portion of the second part or the straight roof portion of the first part. For example, the second fastener may be made shorter so that it terminates within the second part rather than extending through the wall portion. In other alternative embodiments, the orientation of the second fastener may be reversed so that it extends through the second part and then through the spokes to engage with female threads provided on the first part. In yet another alternative embodiment, the second part may be omitted depending on the material used to manufacture the spokes. According to this example, the second fastener may include a nut and bolt, the nut of which engages with the surface of the spoke, or the threaded portion of the second fastener may engage with female threads provided on the spokes.

[0081] Accordingly, the spoke 4200 is attached to the lower ring 4020 by a boot 4215, which is collectively composed of a first part 4217 and a second part 4219, a first fastener 4270, and a second fastener 4272. Specifically, the first part 4217 and the second part 4219 and the second fastener 4272 attach the boot 4215 to the spoke 4200, and the first fastener 4270 attaches the floor portion 4237 to the lower ring 4020. This arrangement provides a robust mounting mechanism for the spokes and allows for the individual removal, maintenance, and installation of each spoke. Additionally, this arrangement does not encroach on areas of spokes that are designed to flex, thereby ensuring that the non-pneumatic tire adequately supports the applied load.

[0082] Although different embodiments and modifications are shown and described in Figures 1 to 22, the disclosed features are not limited to the embodiments described. Instead, various features can be combined between embodiments as needed. For example, the spoke arrangement with boots shown in Figures 15 to 17 may be combined with the curved connecting portion of the spokes shown in Figures 12 and 12a.

[0083] The terms “includes” or “including” are intended to be inclusive, as with the term “comprising,” to the extent used herein or in the claims, and to the extent interpreted when used as a transitional word in a patent claim. Furthermore, the terms “or” are intended to mean “A or B, or both” to the extent used (e.g., A or B). When the 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). Additionally, the terms “in” or “into” are intended to mean “on” or “onto” to the extent used herein or in the claims. Furthermore, to the extent that the term “connect” is used herein or in 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.

[0084] Although this application has been illustrated by the description of its embodiments and described in considerable detail, it is not the applicant's intention to limit the appended claims to such detail or to restrict them in any way. Additional advantages and modifications will be readily apparent to those skilled in the art. Therefore, the broader embodiments of this application are not limited to the specific details, representative apparatus and methods, and examples illustrated and described. For example, each spoke may be provided with a rubber coating to mitigate the impact when contact occurs between adjacent spokes. For this reason, deviations from such details may be made without departing from the spirit or scope of the applicant's general inventive concept.

Claims

1. Non-pneumatic tires, A lower ring having a first diameter, An upper ring having a second diameter, which is substantially coaxial with the lower ring, A support structure for connecting the lower ring to the upper ring, comprising a support structure composed of a plurality of spokes and a plurality of boots corresponding to the plurality of spokes, The plurality of spokes are arranged in a first group of spokes and a second group of spokes spaced axially apart from the first group of spokes, and each of the plurality of spokes is The first end connected to the lower ring, It comprises a second end connected to the upper ring, The boot is configured to accommodate the first end and has a floor portion, the floor portion being attached to the lower ring so as to connect the first end of the spoke to the lower ring, The lower ring is provided with a plurality of scallops, each of which has a first curved surface, and the floor portion of the boot is provided as a second curved surface. Each of the first curved surface and the second curved surface is convex with respect to the inner surface of the lower ring, comprising a support structure, A non-pneumatic tire wherein the first curved surface has a first radius of curvature, the second curved surface has a second radius of curvature equal to the first radius of curvature, and the first center of the first radius of curvature and the second center of the second radius of curvature are located away from the spokes and the boot.

2. The non-pneumatic tire according to claim 1, wherein 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.

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