Self-supporting spoke structure for non-pneumatic tires

Abstract

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

Description

【Technical Field】 【0001】 The present disclosure relates to non-pneumatic tires. More particularly, the present disclosure relates to non-pneumatic tires having a support structure with spokes designed to contact each other during the occurrence of a high-impact event. 【Background Art】 【0002】 Various tire structures have been developed that enable a tire 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 at a relatively high speed for a long time 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 a multi-layer band of material. Such a tread band may also be referred to as a shear band, a shear element, or a 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 at least 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 knee portion is located between the first and second ends. The knee portion is concavely curved relative to the lower ring. 【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 knee portion located between the first end and the second 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 lower ring is connected to the upper ring using the first group of spokes and the second group of spokes. 【0007】 In yet another embodiment, a non-pneumatic tire includes a lower ring having a first diameter and an upper ring having a second diameter. The upper ring is substantially coaxial with the lower ring. A support structure connects the lower ring to the upper ring. The support structure is composed of a plurality of spokes. The support structure is arranged and configured such that when the non-pneumatic tire is in a first state, adjacent spokes of the plurality do not touch each other, and when the non-pneumatic tire is in a second state, adjacent spokes of the plurality touch each other. The first state is when the tire is rolling on a flat surface. The second state is different from the first state. [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] FIG. 13 is another embodiment of a spoke for a non-pneumatic tire. 【BEST MODE FOR CARRYING OUT THE INVENTION】 【0009】 The following includes definitions of selected terms used in this specification. The definitions include various examples or forms of components that are within the scope of the terms and 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 axis of rotation 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 axis of rotation of the tire. 【0013】 As used herein, "tread" refers to the portion of the tire that contacts the road or ground at normal inflation and normal load. 【0014】 General tire components are described by similar terms used in the following description. Of course, since the terms have slightly different implications, those skilled in the art should understand that none of the following terms are purely interchangeable with other terms used to describe general tire components. 【0015】 In this specification, directions are described based on the tire's axis of rotation. The terms "upward" and "upwardly" refer to the general direction towards the tire's tread, and "downward" and "downwardly" refer to the general direction towards the tire's axis of rotation. Thus, when relative directional terms such as "upper" and "lower" or "top" and "bottom" are used in relation to an element, the "upper" or "top" element is spaced closer to the tread than the "lower" or "bottom" element. Additionally, when relative directional terms such as "above" or "below" are used in relation to an element, an element that is "above" another element is closer to the tread than the other element. 【0016】 The terms "inner" and "inwardly" refer to the general direction towards the tire's equatorial plane, and "outer" and "outwardly" refer to the general direction away from the tire's equatorial plane and towards the side of the tire. Thus, when relative directional terms such as "inner" and "outer" are used in relation to an element, the "inner" element is spaced closer to the tire's equatorial plane than the "outer" element. 【0017】 Figures 1 to 5 illustrate one embodiment of the non-pneumatic tire 10. The non-pneumatic tire 10 is merely an exemplary figure and is not intended to be limiting. In the illustrated embodiment, the non-pneumatic tire 10 includes a substantially annular lower ring 20. The lower ring 20 can engage a vehicle hub (not shown) for attaching the tire 10 to a vehicle. The lower ring 20 has an inner surface 23 and an outer surface 24 and can be made from a polymer material, an elastomeric material, a metal, a composite material composed of a polymer reinforced with glass fibers or carbon fibers, or any other desired material or combination of materials. 【0018】 The non-pneumatic tire 10 further includes a substantially annular upper ring 30. The upper ring 30 has a 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 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 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 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 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 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 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, 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 and 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 +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 p1 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 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 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, 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. 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 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. 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 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】 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 was 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 greater 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 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 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】 Figure 13 shows another embodiment of the spoke 2200. The spoke 2200 in Figure 13 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 "2000". 【0053】 The spoke 2200 extends between a first end 2206 and a second end 2208. The foot portion 2214 is provided toward the first end 2206 of the spoke 2200. The foot portion 2214 is attached to the lower ring 20 so as to connect the first end 2206 of the spoke 2200 to the lower ring 20. The second end 2208 of the spoke 2200 is provided with a flexible member 2216. The flexible member 2216 is used to connect the second end 2208 of the spoke 2200 to the upper ring 30. 【0054】 The spoke 2200 includes a knee portion 2222 between a first end 2206 and a second end 2208. A transition portion 2224 is provided between the knee portion 2222 and the first end 2206. A foot portion 2214 extends from the transition portion 2224 to the first end 2206 of the spoke 2200. A first connecting portion 2226 connects the transition portion 2224 to the knee portion 2222. A second connecting portion 2228 connects the knee portion 2222 to the second end 2208 of the spoke 2200. A base plane p1 intersects the transition portion 2224 and the second end 2208 of the spoke 2200, and a second plane p2 extends tangentially to the lower ring 20 at the transition portion 2224. The angle between the base plane p1 and the second plane p2 is α. 【0055】 In the embodiment of spoke 2200 shown in Figure 13, angle α is negative, compared to spokes 200 in Figures 1 to 10, where angle α is positive. As used herein, a positive value of angle α means that the base plane p1 is positioned in front of the second plane p2, using the intersection of the base plane p1 and the second plane p2 as the center point moving clockwise. Using this same reference system, a negative value of angle α means that the base plane p1 is positioned behind the second plane p2. According to one exemplary embodiment, in spoke 2200 shown in Figure 13, angle α is between -30 and 0 degrees. Having a negative value for angle α can result in reduced spoke stress compared to spokes with a positive value for angle α. 【0056】 The non-pneumatic tire described herein improves the robustness of the non-pneumatic tire by providing an arrangement in which adjacent spokes contact each other during 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. 【0057】 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. 【0058】 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 details 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, or to reduce friction or wear during such contact. 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

[Claim 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 plurality of spokes, wherein the plurality of spokes are arranged in at least 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 support structure including a knee portion located between the first end and the second end and curved concavely relative to the lower ring, Each of the plurality of spokes further includes a flexible member, the flexible member being attached to the spoke and the upper ring such that the second end of the spoke connects to the upper ring. Non-pneumatic tires. [Claim 2] The non-pneumatic tire according to claim 1, wherein the spokes of the first group of spokes are curved concavely with respect to the first circumferential direction of the tire, and the spokes of the second group of spokes are curved convexly with respect to the first circumferential direction of the tire. [Claim 3] The non-pneumatic tire according to claim 1, wherein each of the plurality of spokes further includes a connecting portion that connects the knee portion to the second end, and the connecting portion is curved. [Claim 4] The non-pneumatic tire according to claim 1, wherein each of the plurality of spokes further includes a transition portion located between the first end and the knee portion, the transition portion being convexly curved with respect to the lower ring.

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