Leaf spring support for spoke structure of non-pneumatic tire

Abstract

A non-pneumatic tire includes a lower ring having a first diameter and an upper ring having a second diameter greater than the first 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 comprised of a plurality of spokes. The support structure is positioned and configured such that adjacent ones of the plurality of spokes contact one another upon the occurrence of a high impact event.

Description

[Technical Field]

[0001] This disclosure relates to a non-pneumatic tire. More specifically, this disclosure 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. [Background technology]

[0002] Various tire structures have been developed that allow tires to run in a non-inflated or under-inflated state. Non-pneumatic tires do not require inflation, while "run-flat tires" can continue to operate for extended periods at relatively high speeds even after being punctured and partially or completely deflated. Non-pneumatic tires may include support structures such as spokes or webbing that connect the lower ring to the upper ring. In some non-pneumatic tires, the circumferential tread may be attached to the upper ring of the tire.

[0003] A 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 non-pneumatic tires or in partially or non-pneumatic pneumatic tires, the shear element acts as a structural compression member. When used in fully pressurized pneumatic tires, the shear element acts as a tension member.

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

[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 spaced axially apart from the first group of spokes. Each of the plurality of spokes includes a first end connected to the lower ring and a second end connected to the upper ring. A transition portion is located between the first end and the second end. An auxiliary spring is nested with the transition portion of the spoke.

[0006] In another embodiment, a method for manufacturing a non-pneumatic tire includes the steps 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 spokes are formed. Each spoke extends between a first end and a second end. Each spoke has a transition portion between the first end and the second end. Each spoke has an auxiliary spring nested with the transition portion. 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 lower ring is connected to the upper ring using the first and second groups of spokes.

[0007] In yet another embodiment, a non-pneumatic tire includes a lower ring having a first diameter and an upper ring having a second diameter. The upper ring is substantially coaxial with the lower ring. A support structure connects the lower ring to the upper ring. The support structure is composed of a plurality of spokes. Each of the plurality of spokes is provided with an auxiliary spring that nests with the curved portion of the spoke. The auxiliary springs are arranged and configured to reduce stress in the associated spoke. [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 of FIG. 12 along I-I. [Figure 13] Figure 13 is a side view of a part of an alternative embodiment of a non-pneumatic tire. [Figure 14] Figure 14 is a detailed view of a single spoke and an auxiliary spring used in the non-pneumatic tire of FIG. 13. [Figure 14a] Figure 14a is a view along A-A of FIG. 14. [Figure 15] Figure 15 is a detailed view of a part of FIG. 14. [Figure 16a] Figure 16a is a partial modification example of an auxiliary spring. [Figure 16b] Figure 16b is a partial modification example of an auxiliary spring. [Figure 16c] Figure 16c is a partial modification example of an auxiliary spring. [Figure 17a] Figure 17a is a graph showing the performance metrics indicated by the modification examples of the auxiliary spring shown in FIGS. 16a to 16c, respectively. [Figure 17b] Figure 17b is a graph showing the performance metrics indicated by the modification examples of the auxiliary spring shown in FIGS. 16a to 16c, respectively. [Figure 17c] Figure 17c is a graph showing the performance metrics indicated by the modification examples of the auxiliary spring shown in FIGS. 16a to 16c, respectively. [Figure 18a] Figure 18a is a further partial modification example of an auxiliary spring. [Figure 18b] Figure 18b is a further partial modification example of an auxiliary spring. [Figure 18c] Figure 18c is a further partial modification example of an auxiliary spring. [Figure 18d] Figure 18d is a further partial modification example of an auxiliary spring. [Figure 19] Figure 19 is a modification example of the spoke arrangement shown in FIGS. 13 to 15. [Figure 20]Figure 20 shows another variation of the spoke arrangement shown in Figures 13 to 15. [Modes for carrying out the invention]

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

[0010] "Axial" and "in the axial direction" refer to the direction parallel to the tire's axis of rotation.

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

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

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

[0014] While common tire components are described using similar terminology in the following description, it should be understood that, naturally, the terms have slightly different implications, and therefore, those skilled in the art will not consider any of the following terms to be purely interchangeable with other terms used to describe common tire components.

[0015] In this specification, direction is given 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 illustrative and 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 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 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 with adhesive, mechanically, or using any other desired configuration.

[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. These layers may be formed from sheets of material, cords of material, filaments of material, or any other desired configuration. 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 group of spokes 202 and a second group of spokes 204 axially spaced from the first group of spokes 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 spoke group 202 and the second spoke group 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 equipped 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 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 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 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, adhesive, mechanical fasteners (e.g., bolts, rivets), keys / keyways, or any other desired configuration. 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 metal piece, or any other desired material or combination of materials. In the illustrated embodiment, the flexible member 216 is provided as a rectangular parallelepiped and arranged so that its end aligns with the second end 208 of the spoke 200. In other alternative embodiments, the flexible member may be arranged 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 configuration. 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, an additional structure or mechanism 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 connecting portion 226 and the second connecting portion 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 aspects of the spoke 200 with respect to various dimensions. 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 +0 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 p1is is d1. According to one 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 along the direction parallel to the base plane p1is 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 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 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 (see also Figure 5).

[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, when the tire 10 rolls on a flat surface while bearing a load (i.e., normal operation), 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. One example of a high-impact event is the non-pneumatic tire 10 hitting a curb at low speed (e.g., a 6-inch (15-centimeter) curb at 5 miles per hour (8 kilometers per hour)). Another example of a high-impact event is the non-pneumatic tire 10 hitting a bumpy road defect at high speed (e.g., a 1-inch (2.5-centimeter) bump at 70 miles per hour (113 kilometers 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 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 the 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. In addition, 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. In addition, 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 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] In addition, 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 has been found that in order 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. In addition, the spokes may be formed using a plurality of composite material manufacturing techniques (e.g., resin transfer molding and high-pressure resin transfer molding). Further examples of methods for forming spokes include wet layup and prepreg lamination. Each spoke extends between a first end and a second end. A knee portion is located between the first end and the second end, and a transition portion is located between the first end and the knee portion. The knee portion and the transition portion are concavely curved in opposite directions. A foot portion extends from the transition portion.

[0046] In 1030, a flexible member is attached to the spokes. In 1040, the spokes are arranged into 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 in 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 in the second group of spokes are arranged to curve convexly with respect to the first circumferential direction of the tire.

[0047] In 1050, 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 spokes 200 shown in Figures 1 to 10, the radius of curvature r3 of the curved second connecting portion 1228 in the spokes 1200 in Figures 12 and 12a may be changed to affect performance. The radius of curvature r3 of the curved second connecting portion 1228 and the length l of the flexible member 1216. flexure These interact and 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, which results in a straight second connection portion), the effectiveness of self-support begins to decrease again.

[0051] Length l of the flexible member 1216 flexureThis affects 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 a standard load or when subjected to a high-impact event. As a result, the curved second connecting portion 1228 with a smaller radius of curvature r3 has a longer length l flexure The curved second connecting portion 1228, which is optimally matched with the flexible member 1216 having a larger radius of curvature r3, has a shorter length l flexure It was found that the flexible member 1216 having the length l of the flexible member 1216 is optimally matched. The ability of the flexible member 1216 to apply torque to the spoke 1200 is determined by the length l of the flexible member 1216. flexure In addition, it is affected by the stiffness of the material used to manufacture the flexible member 1216. As a result, if a softer material is used, the length l will be affected. flexure A flexible member 1216 is provided having a shorter length l when a harder material is used. flexure It is desirable to provide a flexible member 1216 having the following characteristics.

[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] As described above, the foot portion 214 connects the first end 206 of the spoke 200 to the lower ring 20, and the flexible member 216 connects the second end 208 of the spoke 200 to the upper ring 30. The flexible member 216 provides a relatively flexible connection between the second end 208 of the spoke 200 and the upper ring 30, while the foot portion 214 provides a relatively rigid connection between the first end 206 of the spoke 200 and the lower ring 20.

[0054] According to this embodiment, the spoke 200 behaves like a cantilever, thereby causing the second end 208 to flex (i.e., move) relative to the first end 206 as the tire 10 rolls and deforms. While this behavior is not inherently undesirable, it compresses, stretches, or shears the spoke 200, thereby generating stress in the spoke 200. The maximum stress was found to occur toward the first end 206 of the spoke, particularly near where the attachment between the foot portion 214 and the lower ring 20 ends, spreading through the transition portion 224 and reaching partway to the first connection portion 226.

[0055] Figures 13–15 show alternative non-pneumatic tires with spokes 2200 having features designed to dampen the aforementioned stresses. The embodiments shown in Figures 13–15 are substantially identical to those shown in Figures 1–6, except for any differences described herein. Thus, similar features will be identified by similar numbers, increased by the value "2000".

[0056] Each spoke 2200 has first and second surfaces 2210, 2212, each extending between a first end 2206 and a second end 2208. A foot portion 2214 is provided toward the first end 2206 of the spoke 2200. A flexible member 2216 is provided at the second end 2208 of the spoke 2200. The foot portion 2214 is attached to the lower ring 2020 so as to connect the first end 2206 of the spoke 2200 to the lower ring 2020, and the flexible member 2216 is attached to the upper ring 2030 so as to connect the second end 2208 of the spoke 2200 to the upper ring 2030.

[0057] The knee portion 2222 is provided between a first end portion 2206 and a second end portion 2208. The knee portion 2222 has a first radius of curvature r1. The transition portion 2224 is provided between the knee portion 2222 and the first end portion 2206, and the foot portion 2214 extends from the transition portion 2224 toward the first end portion 2206. The transition portion 2224 has a second radius of curvature r2. The first connection portion 2226 connects the transition portion 2224 to the knee portion 2222. The second connection portion 2228 connects the knee portion 2222 to the second end portion 2208 of the spoke 1200.

[0058] In this embodiment, an auxiliary spring 2500 is provided on the spoke 2200. The auxiliary spring 2500 may be manufactured from a metal (e.g., steel, stainless steel, titanium), a composite material (e.g., carbon fiber reinforced polymer, glass fiber reinforced polymer), or any other desired material or combination of materials. The auxiliary spring 2500 may include a reinforcing member (not shown) or other features that affect the stiffness of the auxiliary spring. In the illustrated embodiment, the auxiliary spring 2500 is a separate and independent component from the spoke 2200. In an alternative embodiment, the auxiliary spring may be integrally formed with the spoke, for example, by folding the end of the spoke onto itself.

[0059] The auxiliary spring 2500 extends between a first end portion 2502 and a second end portion 2504 and has a substantially rectangular cross-section including opposing first and second surfaces 2506, 2508. The auxiliary spring length l hs refers to the total distance between the first end portion 2502 and the second end portion 2504, measured along the longitudinal axis of the auxiliary spring 2500. The auxiliary spring width w hs is the distance between a first edge 2507 and a second edge 2509 of the auxiliary spring 2500 along a direction extending transverse to its length l hs refers to the distance between the first edge 2507 and the second edge 2509 of the auxiliary spring 2500 along a direction extending transverse to its length l. The auxiliary spring thickness t hs refers to the distance between the first surface 2506 and the second surface 2508. In the illustrated embodiment, the auxiliary spring thickness t hsThe thickness of the spoke 2000 is constant between the first end 2502 and the second end 2504. l It is equal to the auxiliary spring width w. hs This is constant between the first end 2502 and the second end 2504 and is equal to the width of the spoke 2000. In an alternative embodiment, the thickness or width of the auxiliary spring may vary between the first end and the second end, or the auxiliary spring and the spoke may have different thicknesses or widths. In another alternative embodiment, the auxiliary spring may have any desired cross-sectional shape, or a combination of different cross-sectional shapes.

[0060] The auxiliary spring 2500 has a curved portion 2510 between the first end 2502 and the second end 2504. In the illustrated embodiment, the curved portion 2510 has a radius of curvature r3 substantially equal to the radius of curvature r2 of the transition portion 2224 of the spoke 2000. In an alternative embodiment, the curved portion may have a different radius of curvature from that of the transition portion.

[0061] The first arm portion 2512 connects its first end 2502 to the curved portion 2510. The second arm portion 2514 connects its second end 2504 to the curved portion. In the illustrated embodiment, both the first and second arm portions 2512 and 2514 are straight. In alternative embodiments, the first or second arm portion may be curved or have any other desired configuration.

[0062] As best shown in Figure 15, the first surface 2506 of the auxiliary spring 2500 is attached to the second surface 2212 of the spoke 2200 along the joining region 2516. The auxiliary spring 2500 can be attached to the spoke 2200 by welding, brazing, soldering, adhesive, mechanical fasteners, or any other desired attachment method. According to this embodiment, the auxiliary spring 2500 is located radially above the spoke 2200 (i.e., the radial distance between the auxiliary spring and the lower ring is greater than the radial distance between the spoke and the lower ring).

[0063] In the illustrated embodiment, the joining region 2516 begins at the first end 2502 of the auxiliary spring 2500 and extends along the length l of the auxiliary spring 2500. hs 33% of the total width of the auxiliary spring w hs Joint length l extending continuously along b The part of the auxiliary spring 2500 that is not joined to the spoke 2200 is called the free part 2571, and has a free length l f In an alternative embodiment, the joining region may extend along 20-100% of the length of the auxiliary spring or 20-100% of the width of the auxiliary spring. In yet another alternative embodiment, the joining region does not have to start at the first end of the auxiliary spring, but instead there may be a non-jointed region of any desired length before the start of the joining region. In yet another alternative embodiment, the joining region may be provided intermittently along the length of the auxiliary spring.

[0064] The auxiliary spring 2500 is arranged relative to the spoke 2200 such that the curved portion 2510 of the auxiliary spring 2500 is nested adjacent to the transition portion 2224 of the spoke 2200. In the illustrated embodiment, the first arm portion 2512 of the auxiliary spring 2500 is sized and configured such that the first end 2502 of the auxiliary spring 2500 aligns with the first end 2206 of the spoke 2200, and the second arm portion 2514 is sized and configured such that the second end 2504 of the auxiliary spring 2500 is located slightly below the midpoint between the transition portion 2224 and the knee portion 2222 of the spoke 2200. In an alternative embodiment, the first or second arm portion may be sized and configured to position the first or second end of the auxiliary spring at any desired position relative to the spoke.

[0065] It has been found that the maximum stress generated during compression of the spokes 2200 is significantly reduced by providing the auxiliary spring 2500. The design parameters of the auxiliary spring 2500, the spokes 2200, and other components of the non-pneumatic tire may be modified to provide the non-pneumatic tire with desired performance characteristics. For example, increasing the length of the second arm portion 2514 of the auxiliary spring 2500 reduces the maximum stress generated in the spokes 2200 but may create greater contact pressure between the auxiliary spring 2500 and the spokes 2200. As another example, increasing the thickness of the auxiliary spring 2500 reduces the maximum stress generated in the spokes 2200 but may increase the contact pressure between the auxiliary spring 2500 and the spokes 2200. In addition, increasing the thickness of the auxiliary spring 2500 may increase the stress within the joint region 2516.

[0066] In the illustrated embodiment, the spoke arrangement includes only a single auxiliary spring 2500. In alternative embodiments, the spoke arrangement may include multiple auxiliary springs. In one exemplary embodiment, each of the multiple auxiliary springs is identical to one another. In other exemplary embodiments, each of the multiple auxiliary springs may have different lengths, thicknesses, and widths, or may be made from different materials, or may have different reinforcing materials, or may have other design variables selected to provide the non-pneumatic tire with desired performance characteristics.

[0067] In addition to the design variables described above, the second end 2504 of the auxiliary spring 2500 may be provided as various planar shapes or with specific edge configurations to further adjust the spokes 2200 and provide performance characteristics to the desired non-pneumatic tire. Figures 16a to 16c show three variations of the planar shape of the second end 2502 of the auxiliary spring 2500, and Figures 17a to 17c are graphs showing performance metrics associated with each design variation. In Figure 16a, the second end 2502 of the auxiliary spring 2500 is square in plan view. This square shape has been shown to allow the entire auxiliary spring 2500 to uniformly support the spokes 2200, resulting in the performance metrics shown and described in Figure 17a. In addition, the square shape has been shown to provide maximum stress reduction in the spokes 2200. In Figure 16b, the second end 2502 of the auxiliary spring 2500 has chamfered corners in plan view. Using oblique corners instead of right-angle corners has been found to reduce the contact pressure between the auxiliary spring 2500 and the spoke 2200, and to result in the performance metrics shown and explained in Figure 17b. In addition, the oblique shape has been found to improve the fatigue performance of the spoke 2200. In Figure 16c, the second end 2502 of the auxiliary spring 2500 is elliptical in plan view. This elliptical shape has been found to provide reduced stress reduction, similar to that of a square end, while also reducing contact pressure, similar to that of a chamfered corner design, and to result in the performance metrics shown and explained in Figure 17c.

[0068] Figures 18a to 18d show four variations of the edge shape of the second end 2502 of the auxiliary spring 2500. Here, “edge” refers to the surface of the auxiliary spring 2500 at the second end 2502 that connects the first surface 2506 to the second surface 2508. In Figure 18a, the second end 2502 of the auxiliary spring 2500 has a chamfered upper portion and a chamfered lower portion, with a straight portion extending between them. When attached to the spoke 2200, the lower portion is adjacent to the second surface 2212 of the spoke 2200. This configuration can reduce localized contact stress, or reduce the tendency for fretting damage to occur by reducing localized contact stress. In Figure 18b, the second end 2502 of the auxiliary spring 2500 has a rounded upper portion and a rounded lower portion, with a straight portion extending between them. This configuration can further reduce the tendency for fretting damage compared to the chamfered design described above. In Figure 18c, the upper and lower portions are chamfered so that the entire second end 2502 is angled. In other words, there is no straight section between the chamfered upper and lower portions. This configuration can provide a similar reduction in local stress and fretting damage as the configuration shown in Figure 18a. In Figure 18d, the upper and lower portions are rounded so that the entire second end 2502 is curved. In other words, there is no straight section between the rounded upper and lower edges. This configuration can further reduce stress than the configuration shown in Figure 18b.

[0069] Figure 19 shows variations of the spoke arrangements in Figures 12-14. The spoke arrangement in Figure 18 is substantially the same as the spoke arrangements in Figures 12-14, except for the differences described herein. Therefore, similar features are identified by similar numbers that are increased by "1000".

[0070] In the modified configuration shown in Figure 19, the second surface 3508 of the auxiliary spring 3500 is attached to the first surface 3210 of the spoke 3200, and the second end 3208 of the spoke 3200 is attached to the lower ring 3020 by attaching the first surface 3506 of the auxiliary spring 3500 to the lower ring 3020. In this embodiment, the auxiliary spring 3500 is located radially below the spoke 3200 (i.e., the radial distance between the auxiliary spring and the lower ring is smaller than the radial distance between the spoke and the lower ring). By placing the auxiliary spring 3500 radially below the spoke 3200, the load support efficiency by tension or shear force can be improved. In another modified configuration (not shown), two auxiliary springs may be attached to the spoke (i.e., one auxiliary spring may be positioned above the spoke and the other below the spoke), with the first auxiliary spring attached to the second surface of the spoke and the second auxiliary spring attached to the first surface of the spoke.

[0071] Figure 20 shows another variation of the spoke arrangement shown in Figures 12-14. The configuration in Figure 20 is substantially the same as that in Figures 12-14, except for the differences described herein. Thus, similar features will be identified by similar numbers, increased by only "4000".

[0072] According to the modified configuration shown in Figure 20, the buffer portion 4519 is provided between the auxiliary spring 4500 and the spoke 4200, specifically between the free portion 4517 of the spoke 4200 adjacent to the joint area 4516. The buffer portion 4519 is positioned and configured to minimize the occurrence of stress-induced damage as a result of any contact between the auxiliary spring 4500 and the spoke 4200. In the illustrated embodiment, the buffer portion 4500 is a separate component from both the auxiliary spring 4500 and the spoke 4200 and may be manufactured from plastic, metal, carbon fiber reinforced polymer, glass reinforced polymer, ceramic, or any other desired material or combination of materials. The buffer portion 4519 may be attached to the auxiliary spring 4500 or the spoke 4200 using adhesive, mechanical fasteners, brazing, soldering, welding, or any other desired configuration. In an alternative embodiment, the buffer portion may be directly integrated with the auxiliary spring or spoke. In another alternative embodiment, the buffer portion may be a coating applied to the spoke or auxiliary spring. In yet another embodiment, the buffer portion may be a thin void. For example, the void may be 0.0020 inches (0.05 mm) thick.

[0073] Although different embodiments and variations have been shown and described in various figures, the disclosed features are not exclusive to each of the described embodiments. Instead, various features from different embodiments or variations can be combined as desired.

[0074] 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.

[0075] Although this application has been illustrated by the description of its embodiments, and its embodiments have been 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 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 connecting the lower ring to the upper ring, comprising a plurality of spokes, wherein 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, The second end connected to the upper ring, A transition portion located between the first end and the second end, A foot portion located between the transition portion and the first end, and connected to the lower ring together with the first end, The aforementioned spoke includes the aforementioned transition portion and an auxiliary spring nested within it, The auxiliary spring is attached to the foot portion of the spoke, and is a non-pneumatic tire.

2. The non-pneumatic tire according to claim 1, wherein the auxiliary spring is positioned on the leg portion of the spoke on the side opposite to the lower ring.

3. The non-pneumatic tire according to claim 1, wherein the auxiliary spring is disposed between the foot portion of the spoke and the lower ring.

4. The non-pneumatic tire according to claim 1, wherein the auxiliary spring includes a curved portion between a first end and a second end, and the radius of curvature of the curved portion is substantially equal to the radius of curvature of the transition portion of the spoke.

5. The non-pneumatic tire according to claim 1, wherein the auxiliary spring is attached to the spoke along a joining region, and the joining region extends along 20% ​​to 100% of the length of the auxiliary spring.

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