Field

[0001] Embodiments of this disclosure relate generally to non-pneumatic tires. BACKGROUND

[0002] Mechanical structures for resiliently supporting a load, such as spokes for use with non-pneumatic tires and tire carcasses, have been employed previously.

[0003] Current non-pneumatic tires develop most of their spoke tension when the tire is loaded against the ground. To develop sufficient tension to carry the vertical load at reasonable deflections, non-pneumatic tire spokes must have a relatively high spring rate. Simulation and experimentation show that this high spring rate leads to undesirably high force transmission to the wheel hub during a dynamic loading event. Accordingly, it is desirous to develop spokes for a non-pneumatic tire that reduce undesirable high force transmissions to the wheel hub during dynamic loading events.

SUMMARY

[0004] Embodiment of this disclosure include non-pneumatic tires and tire carcasses, spokes for forming the same, and methods of forming each. In particular embodiments, the tire carcass includes an outer band comprising a reinforced polymeric ring, the outer band having a thickness bounded by an outer side and an inner side, the inner side being arranged radially inward of the outer side. Such tire carcass further includes an inner hub comprising a rigid annular member, the inner hub having a radially outer side. The tire carcass also includes a plurality of spokes forming a lattice structure around the tire, where each spoke of the plurality has a length extending at an angle biased from a radial direction of the tire, each such spoke extending from the inner hub and to the outer band and intersecting at least one other spokes of the plurality of spokes, each of the plurality of spokes formed of a polymeric material.

[0005] It follows that this disclosure also provides methods for assembling or forming a non- pneumatic tire or tire carcass. In addition to the disclosure above, which discusses aspects of such methods, in particular instances, such methods include providing an outer band comprising a reinforced polymeric ring, the outer band having a thickness bounded by an outer side and an inner side, the inner side being arranged radially inward of the outer side. Any such band may be employed as known to one of ordinary skill. Such method further include providing an inner hub comprising a rigid annular member, the inner hub having a radially outer side. Any such hub may be employed as known to one of ordinary skill. Such methods further include providing a plurality of spokes forming a lattice structure around the tire carcass, such as any discussed or contemplated herein. Each spoke of the plurality has a length extending at an angle biased from a radial direction of the tire carcass, each such spoke extending from the inner hub and to the outer band and intersecting at least one other spokes of the plurality of spokes, each of the plurality of spokes formed of a polymeric material. Such methods further include radially stretching the lattice structure into a stretched arrangement, and affixing the lattice structure in the stretched arrangement to both the outer band and the inner hub.

[0006] The foregoing and other objects, features, and advantages will be apparent from the following more detailed descriptions of particular embodiments, as illustrated in the accompanying drawings wherein like reference numbers represent like parts of particular embodiments.

DETAILED DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a lateral side elevational view of a carcass portion of a non-pneumatic tire, the non-pneumatic tire carcass including a plurality of spokes forming a lattice and affixed to an outer band and an inner hub, in accordance with an exemplary embodiment;

[0008] FIG. 2 is a side view of a plurality of spokes forming a portion of the lattice similar to the tire shown in FIG. 1 in an undeformed, pre-installed arrangement;

[0009] FIG. 3 is a side sectional view of the spoke shown in FIG. 2 taken along a width of the spoke; and,

[0010] FIG. 4 is a side view of the lattice portion shown in FIG. 2 overlaid by the lattice portion shown stretched in an installed arrangement as shown in FIG. 1.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0011] The present disclosure provides mechanical structures for resiliently supporting a load, as well as non-pneumatic tires and non-pneumatic tire carcasses (each forming a portion of a non-pneumatic tire) incorporating the mechanical structures, in the form of a spoke, where a plurality of spokes are employed by said non-pneumatic tire. For purposes of describing the invention, reference now will be made in detail to embodiments and/or methods of the invention, one or more examples of which are illustrated in or with the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features or steps illustrated or described as part of one embodiment, can be used with another embodiment or steps to yield a still further embodiments or methods. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0012] The following terms are defined as follows for this disclosure:

[0013] "Axial direction" or the letter "A _d " in the figures refers to a direction parallel to the axis of rotation of for example, the outer band, tire, and/or inner hub as it travels along a ground surface.

[0014] "Radial direction" or the letter "R _d " in the figures refers to a direction that is orthogonal to the axial direction and extends in the same direction as any radius that extends orthogonally from the axial direction.

[0015] "Circumferential direction" or the letter "C _d " in the figures refers to a direction is orthogonal to the axial direction and orthogonal to a radial direction.

[0016] "Forward direction of travel" or the letter "F _d " in the figures refers to the direction the tire was designed to predominantly travel in for aesthetics and or performance reasons. Travel in a direction different than the forward direction of travel is possible and anticipated.

[0017] "Direction of rotation" or the letter "R" in the figures refers to the direction the tire was designed to predominantly rotate in for aesthetics and/or performance reasons. Rotation in a direction opposite than the direction of rotation is possible and anticipated.

[0018] "Lateral direction" or "widthwise direction" or the letter "Lat _d " is synonymous with axial direction.

[0019] "Elastic material" or "elastomer" as used herein refers to a polymer exhibiting rubberlike elasticity, such as a material comprising rubber, whether natural, synthetic, or a blend of both natural and synthetic rubbers. [0020] "Elastomeric" as used herein refers to a material comprising an elastic material or elastomer, such as a material comprising rubber.

[0021] "Modulus" or "Modulus of elongation" (MPa) was measured at 10% (MA 10) at a temperature of 23 °C based on ASTM Standard D412 on dumb bell test pieces. The measurements were taken in the second elongation; i.e., after an accommodation cycle. These measurements are secant moduli in MPa, based on the original cross section of the test piece.

[0022] "Rigid" as used herein means unable to bend or be forced out of shape without plastic deformation; not flexible.

[0023] "Nominal load" or "design load" is a load for which the structure is designed to carry. More specifically, when used in the context of a wheel or tire, "design load" refers to the load for which the wheel or tire is designed to carry and operate under. The design load includes loads up to and including the maximum load specified by the manufacturer and, in the case of a vehicle tire, often indicated by marking on the side of a the tire. A loading condition in excess of the design load may be sustained by the structure, but with the possibility of structural damage, accelerated wear, or reduced performance. A loading condition of less than design load, but more than an unloaded state, may be considered a nominal load, though deflections will likely be less than deflections at nominal load.

[0024] With reference to an exemplary embodiment shown in FIG. 1, a non-pneumatic tire 10 is shown to include a tread 20 and a carcass portion 30 of non-pneumatic tire 10, all of which are annular. Carcass 30, and therefore tire 10, more specifically includes an outer band 40, an inner hub 50, and a plurality of spokes 60 arranged between outer band 40 and inner hub 50, and to which each of the spokes 60 are operably affixed. The rotational axis A of tire 10, carcass 30, and the components of each is also shown, and defines any radial or axial direction referred to herein unless otherwise noted.

[0025] With continued reference to FIG. 1, carcass 30 forms the portion of a non-pneumatic tire 10 to which annular tread 20 is operably attached. Tread 20 is arranged to extend around outer radial side 32 of carcass 30. Tread 20 defines an outer, ground-engaging side of non- pneumatic tire 10, which extends annularly around the non-pneumatic tire 10 and outer band 40.

[0026] In the embodiment shown in FIG. 1, the outer radial side 32 of carcass 30 is also an outer radial side 42 of outer band 40. Outer band 40, which is also referred to as a shear band, comprises a reinforced polymeric ring including a plurality of reinforcement layers (not shown), each such layer formed of an elastomeric matrix including a plurality of elongate reinforcements. Therefore, outer band 40 is characterized as being a reinforced, flexible structure. Outer band 40 has a thickness bounded by an outer radial side 42 and an inner radial side 44, the inner side 44 being arranged radially inward of the outer side 42. Outer band 40 is not configured to retain any pressurized air.

[0027] In the embodiment of FIG. 1, inner hub 50, also referred to as a central annular portion, forms an inner annular portion that is rigid and capable of being operably attached to a vehicle directly or by way of a wheel to which hub 50 is attached or of which hub 50 forms a portion thereof. By virtue of hub 50, non-pneumatic tire 10 may be installed on a vehicle to allow the vehicle to roll across a ground surface. It is appreciated that the non-pneumatic tire 10 may be mounted upon any desired wheeled vehicle, such as, but not limited to: passenger vehicles, heavy duty trucks, trailers, light trucks, off-road vehicles, ATVs, buses, aircrafts, agricultural vehicles, mining vehicles, bicycles, and motorcycles. Inner hub 50 includes an outer radial side 52 to which the plurality of spokes 60 are attached.

[0028] As noted previously, spokes 60 are attached to an outer radial side 52 of inner hub 50 and also to an inner radial side 44 of outer band 40. In each instance, spokes 60 may be attached in any manner, such as, for example and without limitation, by mechanical fasteners such as bolts, screws, clamps or slots, and/or by adhesives such as cyanoacrylates, polyurethane adhesives, and/or by other bonding materials or any combination thereof.

[0029] With continued reference to FIG. 1, non-pneumatic tire 10, during operation when rolling along a ground surface in direction F _d while exposed to a downward vertical load component, outer band 40 and spokes 60 each deform and flex as the non-pneumatic tire 10 enters and exits a contact patch, which is the area of contact between the tire 10 and the ground surface. While smaller deflections may occur in each spoke 60 outside the contact patch as each such spoke 60 rotates around the tire 10 and rotational axis A, the primary spoke deflection occurs as each spoke 60 enters, travels through, and exits the contact patch.

[0030] With reference now to FIG. 1, non-pneumatic tire carcass 30 includes a plurality of spokes 60 arranged between outer band 40 and inner hub 50, where the spokes 60 are shown in an installed arrangement. In the installed arrangement, each spoke extends from the inner hub 50 and to the outer band 40. Each spoke 60 has a length Leo extending at an angle a biased from a radial direction R _d of tire 10. The plurality of spokes 60 are arranged generally arranged, in any embodiment, to intersect one or more other spokes 60 to form a lattice structure extending around the tire.. In the embodiment shown in FIG. 1, each spoke intersects multiple other spokes within the plurality of spokes. It is appreciated that angle a measure any desired angle greater than zero and less than 90 degrees in absolute value. In particular instances, for example and without limitation, in an installed arrangement, spoke angle a is 30 to 60 degrees. If being stretched for installation within the tire, which may be optional in certain embodiments, in an unstretched arrangement spoke angle a is greater, perhaps 50 to 70 degrees, depending on the outer band and hub geometry.

[0031] Each of the plurality of spokes 60 is formed of a polymeric material. It is appreciated that any suitable polymeric material may be employed, in certain exemplary embodiments the polymeric material is an elastomeric, low modulus material, such as natural or synthetic rubber, or any blend thereof. For example, such low modulus material has a Modulus of 1 to 10 megapascals (MPa). By virtue of arranging the spokes to form a lattice structure, the use of low modulus polymeric material may be employed, where the lattice structure and spokes are stretched to be placed in tension to preload the spokes. The combination of this low modulus material and spoke geometry result in a much lower spring rate of the spoke, which in turn reduces the transient force transmission to the wheel hub during a dynamice loading event. This design allows the natural collapsing or folding of the spokes in an dynamic overload event, such as a pothole strike. This would further reduce the transient force transmission to the wheel hub during a dynamice loading event by unloading the spokes near the obstacle point of contact. The deflection required to totally unload the spoke at the center of the contact patch is designed to be beyond the flat surface deflection operating point, usually prescribed by the maximum operating load of the tweel. Current non-pneumatic tires using non-lattice spokes operate partially in bending, which requires either a composite material or a base material of much higher modulus, or a combination of the two. This lattice design uses spokes in tension, where loading stresses are generally uniform in the spoke and minimal bending stresses are present. Because the lattice spoke material will operate at a bulk cyclic strain of 30%, which is much higher than is normally observed by other non-pneumatic, non-lattice spokes.

[0032] With reference to an exemplary embodiment in FIG. 2, it is appreciated that spoke 60 has a thickness Τβο as measured normal to its width W ₆ o and length Leo (that is, relative to a lengthwise centerline located midway through the spoke thickness Τβο). In the embodiment shown, each spoke 60 has a constant thickness arranged along its length Leo, although thickness Τβο may be variable in other variations. Exemplary spoke thickness range from 1 to 5 millimeters (mm).

[0033] With regard to the lattice, with reference to an unstretched arrangement in FIG. 2, it can be said that the plurality of spokes 60 includes a first plurality of spokes 60i and a second plurality of spokes 6Ο2, each spoke 6O1 of the first plurality being positively biased by angle +0C relative to a radial direction R _d of the tire 10 and each spoke 6Ο2 of the second plurality being negatively -a biased relative to a radial direction R _d of the tire 10. This is also observed in the embodiment shown in FIG. 1. With reference to FIG. 4 and a stretched lattice arrangement when installed on a tire, each spoke 6O1 of the first plurality being positively biased by angle +<¾' relative to a radial direction R _d of the tire 10 and each spoke 6Ο2 of the second plurality being negatively -a' biased relative to a radial direction R _d of the tire 10, where unstretched angle -a for the first plurality of spokes 6O1 in absolute value is greater than stretched angle -a' in absolute value and unstretched angle +a for the second plurality of spokes 6Ο2 is greater than stretched angle +α'.

[0034] With particular reference to the exemplary embodiment shown in FIG. 2, a lattice is shown in a pre-installation (unstretched) arrangement, where the lattice has not yet been stretched in a radial direction to extend from the outer band 40 and to the inner hub 50 as is generally shown in FIG. 1 with regard to a different lattice structure (one having less frequently intersecting spokes). In this unstretched arrangement, the lattice formed by the plurality of spokes 60 can be described in a manner whereby each spoke 6O1 from the first plurality of spokes intersects a different spoke 6Ο2 from the second plurality at intersection Xi along a first common radius Ri located a first distance Di from an inner radius Ri along which an inner hub-engaging end 62 of each spoke 60 is located. With reference now to FIG. 4, when stretched into an installed arrangement, each spoke 6O1 from the first plurality of spokes intersects a different spoke 6Ο2 from the second plurality at intersection Xi along a first common radius Ri' located a first distance Di' from the inner hub 50 (or from inner hub radius R,') between the inner hub 50 and the outer band 40.

[0035] With reference again to FIG. 2, each spoke 6O1 from the first plurality of spokes intersects another different spoke 6Ο2 from the second plurality at intersection X2 along a second common radius R2 located a second distance D2 from first common radius Ri, the second distance D2 being greater than the first distance Di. With reference now to FIG. 4, when stretched into an installed arrangement, each spoke 60i from the first plurality of spokes intersects a different spoke 6Ο2 from the second plurality at intersection X2 along a second common radius R2' located a second distance D2' from the first common radius Ri' between the inner hub 50 and the outer band 40, the second distance D2' being greater than the first distance Di'.

[0036] With reference again to FIG. 2, each spoke 6O1 from the first plurality of spokes intersects another different spoke 6Ο2 from the second plurality at intersection X ₃ along a third common radius R ₃ located a third distance D ₃ from second common radius R ₂ , the third distance D ₃ being greater than the second distance D ₂ . With reference now to FIG. 4, when stretched into an installed arrangement, each spoke 6O1 from the first plurality of spokes intersects a different spoke 6Ο2 from the second plurality at intersection X3 along a third common radius R3' located a third distance D3' from second common radius R2' between the inner hub 50 and the outer band 40, the third distance D3' being greater than the second distance D2'.

[0037] With regard each intersection Xi along the first radius Ri or Ri', each is aligned radially (in a radial direction R _d ) with one intersection X ₃ along corresponding third radius R ₃ or R ₃ ', and where each intersection X2 along corresponding second radius R2 or R2' is arranged in an annular direction C _d midway between radially aligned intersections Xi and X ₃ along the first radius and the third radius.

[0038] It is appreciated that the distance between each of the first, second, and third radius may be any equal or unequal distances as is desired. In the embodiment shown in FIG. 2 in the unstretched arrangement, however, the difference (distance D2) between the first radius Ri and the second radius R2 is less than the difference (distance D3) between the second radius R2 and the third radius R ₃ . The same is true for the stretched arrangement in FIG. 4.

[0039] In the embodiment discussed in the prior paragraphs, it is appreciated that the inner hub-engaging ends 62 of each of the spokes 60 between the first and second pluralities may or may not intersect one another. Likewise, it is appreciated that the outer band-engaging ends 64 of each of the spokes 60 between the first and second pluralities may or may not intersect one another. In the embodiment shown in FIG. 4, where the lattice is shown in an installed, stretched arrangement, each spoke 6O1 of the first plurality extends outwardly from the inner hub 50 at a hub intersection location Xi from which another spoke 6Ο2 of the second plurality extends outwardly from the inner hub 50. Likewise, each spoke 6O1 of the first plurality extends outwardly from the outer band 40 at a band intersection location Xo from which yet another spoke 6Ο ₂ of the second plurality extends outwardly from the outer band 40. In unstretched arrangement in FIG. 2, it can be said that each spoke 6O ₁ , 6Ο ₂ intersects at, or emanates from, a common location Xi along inner radius Ri. It can also be said that each spoke 6O ₁ , 6Ο ₂ intersects at, or emanates from, a common location Xo along outer radius Ro. It is appreciated that in the embodiment shown, optionally, each hub intersection location Xi is circumferentially arranged (positioned) to be radially aligned with a corresponding band intersection location Xo and with a corresponding intersection X ₂ along the second radius R ₂ or R ₂ ', where each such intersection is arranged midway in an annular direction (circumferentially) between radially aligned intersections along the first radius Ri or Ri' and the third radius R3 or R3'.

[0040] It is appreciated that in other variations, any spoke 60 may intersect only once or any plurality (2 or more) of other spokes when extending from the inner hub and to the outer band. While a progressively increased spacing between common radii is shown in the present embodiments (by virtue of increasing distances Di, D ₂ , D3), it is appreciated that any desired increase, decreased, or constant spacing between common intersection radii may be employed as desired. In sum, all geometry selected to optimize stress and strain, so not to over stress any portion of the lattice and allow minimum force transfer to the hub during an dynamic overload event, such as a pothole strike.

[0041] With reference to FIG. 3, a widthwise view of the lattice formed by the plurality of spokes 60 is shown. In particular, the spokes 60 have a width W60 extending in a lateral (that is, widthwise or axial) direction Lat _d - The height Ηβο is also shown, which can be measured between inner ends 62 and outer ends 64 in a direction perpendicular to both spoke width W60 and a circumferential direction of the lattice , that is, in a radial direction of the tire or tire carcass. Radii Ri, R _l5 R ₂ , R3, and Ro are shown each identifying a radius along which a plurality of spaced apart intersections Xi, Xi, X ₂ , X3, Xo occur between spokes 6O ₁ , 6Ο ₂ from the first and second pluralities of spokes around tire 10.

[0042] As has been discussed, the plurality of spokes are provided initially in an unstretched, uninstalled arrangement, and subsequently is stretched when installed as a component of a non-pneumatic tire or tire carcass. In the exemplary embodiment shown in the figures, the lattice formed by the plurality of spokes is stretched in a radial direction, whereby the unstretched height Ηβο in an uninstalled arrangement is increased (see FIG. 4 for example) to a stretched height Ηβο' in an installed arrangement. Because the lattice structure is elastic, by stretching the lattice, the lattice and the spokes are pre-tensioned in the installed arrangement while the tire is in an undeformed (unloaded) state.

[0043] It follows that this disclosure also provides methods for assembling or forming a non- pneumatic tire or tire carcass. In addition to the disclosure above, which discusses aspects of such methods, in particular instances, such methods include providing an outer band comprising a reinforced polymeric ring, the outer band having a thickness bounded by an outer side and an inner side, the inner side being arranged radially inward of the outer side. Any such band may be employed as known to one of ordinary skill. Such method further include providing an inner hub comprising a rigid annular member, the inner hub having a radially outer side. Any such hub may be employed as known to one of ordinary skill. Such methods further include providing a plurality of spokes forming a lattice structure around the tire carcass, such as any discussed or contemplated herein. Each spoke of the plurality has a length extending at an angle biased from a radial direction of the tire carcass, each such spoke extending from the inner hub and to the outer band and intersecting at least one other spokes of the plurality of spokes, each of the plurality of spokes formed of a polymeric material. Such methods further include radially stretching the lattice structure into a stretched arrangement, and affixing the lattice structure in the stretched arrangement to both the outer band and the inner hub.

[0044] To the extent used, the terms "comprising," "including," and "having," or any variation thereof, as used in the claims and/or specification herein, shall be considered as indicating an open group that may include other elements not specified. The terms "a," "an," and the singular forms of words shall be taken to include the plural form of the same words, such that the terms mean that one or more of something is provided. The terms "at least one" and "one or more" are used interchangeably. The term "single" shall be used to indicate that one and only one of something is intended. Similarly, other specific integer values, such as "two," are used when a specific number of things is intended. The terms "preferably," "preferred," "prefer," "optionally," "may," and similar terms are used to indicate that an item, condition or step being referred to is an optional (i.e., not required) feature of the embodiments. Ranges that are described as being "between a and b" are inclusive of the values for "a" and "b" unless otherwise specified. [0045] While various improvements have been described herein with reference to particular embodiments thereof, it shall be understood that such description is by way of illustration only and should not be construed as limiting the scope of any claimed invention. Accordingly, the scope and content of any claimed invention is to be defined only by the terms of the following claims, in the present form or as amended during prosecution or pursued in any continuation application. Furthermore, it is understood that the features of any specific embodiment discussed herein may be combined with one or more features of any one or more embodiments otherwise discussed or contemplated herein unless otherwise stated.