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. However, certain prior art spokes generate excessively high lateral stiffness, which was much higher than the lateral stiffness associated with a corresponding pneumatic tire. Additionally, certain prior art spokes generate elevated aerodynamic drag, resulting in a desire to reduce such drag to provide improved performance and reduced fuel consumption. There is also a need to reduce rolling resistance, and to better accommodate deradialization of the tire during operation.

SUMMARY

[0003] Embodiments of the disclosure include a non-pneumatic tire, a non-pneumatic tire carcass, and a plurality of spokes for arrangement in either. In particular embodiments, the tire carcass comprises 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. The carcass includes an inner hub comprising a rigid annular member, the inner hub having a radially outer side. The carcass also includes a first plurality of sidewall spokes and a second plurality of sidewall spokes. Each plurality of spokes is arranged along one of a pair of opposing axial sides of the non-pneumatic tire carcass in a spaced-apart annular array between the inner hub and the outer band. Each spoke is connected to each of the inner hub and the outer band. Each spoke is resilient and has an outer band portion, an inner hub portion, and a connecting portion connecting the inner hub portion and the outer band portion. Inner hub portion and the outer band portion are each spaced apart in a radial direction of the tire. The connecting portion is arcuate in length such that each spoke length is generally U or V-shaped. The outer band portion is substantially fixed along the outer band. The inner hub portion extends lengthwise from the connecting portion and to an inner terminal end, the terminal end being attached to the inner hub by way of a resilient joint, where each spoke extends lengthwise from the inner terminal end of the inner hub portion and axially outward toward one of the pair of opposing axial sides and to the connecting portion, where the spoke continues to extend lengthwise and transition from extending axially outward to extending axially inward upon reaching the outer band portion of the spoke, the outer band portion extending axially from the connecting portion. It is appreciated that other variations of the carcass or non-pneumatic tire incorporating said carcass may vary by incorporating more or less features as described hereinafter, or by varying the present features as described hereinafter.

[0004] 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

[0005] FIG. 1 is a lateral side elevational view of a non-pneumatic tire, the non-pneumatic tire including a plurality of spokes affixed to an outer band and an inner hub, in accordance with an exemplary embodiment;

[0006] FIG. 2 is a sectional view of the tire shown in FIG. 1, taken along line 2-2, the image showing a pair of opposing U-shaped spokes arranged on opposing lateral (axial) sides of the tire, in accordance with an exemplary embodiment;

[0007] FIG. 3 is a side view of a pair of opposing spokes shown in FIG. 2;

[0008] FIG. 4 is an end view of a spoke shown in FIG. 3;

[0009] FIG. 5 is a side view of a pair of opposing spokes attached to an outer band in accordance with another exemplary embodiment;

[0010] FIG. 6 is a radially outward view of a spoke, showing the effects of deradialization;

[0011] FIG. 7 is a side view of the pair of opposing spokes of FIG. 3 shown in a pre tensioned arrangement; and,

[0012] FIG. 8 is a side view of the pair of opposing spokes shown deflected during normal tire operation.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0013] The present disclosure provides mechanical structures for resiliently supporting a load, as well as non-pneumatic tires and non-pneumatic tire carcasses 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 will now be made to particular exemplary embodiments , one or more examples of which are illustrated in particular figures, or in association with particular figures. 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.

[0014] The following terms are defined as follows for this disclosure:

[0015]“Axial direction” or the letter“A _d ” in the figures refers to a direction parallel to the axis of rotation A of the tire or tire carcass, and its components, such as the outer band and inner hub, when rolling along a ground surface.

[0016]“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.

[0017]“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.

[0018]“Lateral direction” or“widthwise direction” is synonymous with axial direction A _d -

[0019]“Elastic material” or“elastomer” as used herein refers to a polymer exhibiting rubber like 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]“Interior angle” or“internal angle” as used herein means an angle formed between two surfaces that is greater than 0 degrees but less than 180 degrees. An acute angle, a right angle and an obtuse angle would all be considered“interior angles” as the term is used herein. [0022]“Modulus” or“Modulus of elongation” (MPa) was measured at 10% strain (MA10) 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.

[0023]“Resilient” as used herein means configured to bend and flex elastically without plastic or permanent deformation under intended operating conditions.

[0024]“Rigid” as used herein means generally unable to elastically or plastically bend or be forced out of shape under intended operating conditions, as opposed to being resilient.

[0025] With reference to an exemplary embodiment shown in FIG. 1, a non-pneumatic tire 10 is shown to include a tread 20 arranged annularly around a carcass portion of non pneumatic tire 10. In doing so, tread 20 defines an outer, ground-engaging side 12 of non pneumatic tire 10. The carcass includes an outer band 30, an inner hub 40, and a plurality of spokes 50 arranged between outer band 30 and inner hub 40, and to which each of the spokes 50 are operably affixed. In particular, a first plurality of spokes PI50 is arranged on one lateral side LS of the tire 10 to operate as a tire sidewall 14 while a second plurality of spokes P25o is arranged along other opposing lateral side (not shown) to also operate as a tire sidewall. The rotational axis A of tire 10 and tire carcass, and of the annular components of each is also shown, which defines any radial or axial direction referred to herein unless otherwise noted.

[0026] With continued reference to FIG. 1, it is more specifically noted that in extending around an outer radial side of the carcass, tread 20 extends annularly around the outer band 30. In the embodiment shown in FIG. 1, the outer radial side of the carcass is also an outer radial side 32 of outer band 30. Outer band 30, 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. The elongate reinforcements may comprise any desired cable or cord, for example. Therefore, outer band 30 is characterized as being a reinforced, flexible structure. Outer band 30 has a thickness bounded by an outer radial side 32 and an inner radial side 34, the inner side 34 being arranged radially inward of the outer side 32. Outer band 30 is not configured to retain any pressurized air. [0027] Inner hub 40 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 40 is attached or of which hub 40 forms a portion thereof. By virtue of hub 40, 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 40 includes an outer radial side 42 to which the plurality of spokes 50 are attached.

[0028] With specific reference to FIG. 2, a sectional view of the non-pneumatic tire 10 is shown, taken along a plane extending in both a radial direction R _d and an axial direction A - In this figure, tread 20 is shown arranged adjacent to, and radially outward of outer band 30. Opposing spokes 50 are also shown, where each is operably attached to each of the outer band 30 and the inner hub 40. Each opposing spoke 50 is associated with one of a first plurality of spokes PI50 (also shown in FIG. 1) and a second plurality of spokes P2so (not shown in FIG. 1, but located axially opposite the first plurality of spokes PI50), each plurality of spokes PI50, P25o arranged along one of a pair of opposing axial (lateral) sides LS of the non-pneumatic tire 10 or of the tire carcass in a spaced-apart annular array between the inner hub and the outer band. Each spoke 50, together with the other spokes 50 arranged in an array along the same lateral side LS operate as a sidewall 14 of the tire 10, such that the plurality of spokes 50 arranged on opposing lateral sides LS of the tire 10 operate as a pair of sidewalls 14, akin to a pair of sidewalls as is included within typical pneumatic tires. And just as the sidewalls of a pneumatic tire flex and deflect when loaded, so do each of the spokes 50 when the tire 10 is loaded. Accordingly, each spoke 50 is characterized as being resilient and may also referred to more specifically as a sidewall spoke.

[0029] With reference now to FIGS. 2 and 3, each spoke has an outer band portion 52, an inner hub portion 54, and a connecting portion 56 connecting the outer band portion 52 and the Outer band portion 52 and inner hub portion 54 are spaced apart in a radial direction R _d of the tire 10 or of the tire carcass. The connecting portion 56 is generally arcuate in length, such that the connecting portion 56 is generally U-shaped or V-shaped. In the embodiment shown, the lengthwise extension L50 of each spoke 50, which includes the outer band portion 52, the inner hub portion 54, and the connecting portion 56, is generally U-shaped. While connecting portion 56 may form any arcuate U or V-shaped path, in the embodiment shown, the arcuate length of the connecting portion extends along (is defined by) a single (constant) radius rs ₆ . In other variations, the arcuate length may extend along multiple radii.

[0030] With continued reference to FIGS. 2 and 3, outer band portion 52 has a length L52 configured to extend along the outer band 30. In doing so, the entire length L52 is not required to fully engage the inner radial side 34 of outer band 30, even though it does so in the embodiment shown. Instead, outer band portion 52 is substantially fixed to the outer band 30 along its length L ₅₂ , while length L ₅₂ may extend along any desired linear or non linear path. For example, the lengthwise path for length L ₅₂ may vary in the radial direction R _d and/or in the circumferential direction C _d (shown in FIG. 1). In the exemplary embodiment shown, length L ₅₂ extends linearly in the axial direction A _d without extending in either the radial direction R _d and/or the circumferential direction C _d - In being substantially fixed, a substantial portion of the outer band portion does not pivot or move. In affixing the outer band portion 52 to the outer band 30, attachment may be accomplished in any desired manner, such as by use of an adhesive or by use of an elastomer (such as cushion gum) that is cured through vulcanization to secure the spoke to the outer band 30.

[0031] With continued reference to FIG. 2, inner hub portion 54 is fixed to inner hub 40 at a resilient joint 60. Resilient joint 60 is formed by arranging elastomeric material 62 between inner hub portion 54 and an inner hub connector 64. In the embodiment shown, this occurs at a free, terminal end 54E (see FIG. 3) of inner hub portion 54, where elastomeric material 62 is arranged on opposing radial sides of the spoke thickness tso at the terminal end 54E. The elastomeric material 62 is arranged to have a length L ₆ 2 sufficient to engage the spoke 50. In one exemplary embodiment, elastomeric material length L ₆₂ is equal to at least 10 millimeters (mm), and in certain embodiments, from 10 mm to 20 mm, as measured in the direction of the spoke length L ₅₀ . Elastomeric material 62 also has a thickness t ₆₂ , which may range from 1 mm to 6 mm. Generally, the elastic material length L ₆₂ and thickness 2 are each selected to sufficiently provide the ability for a corresponding spoke 50 to pivot during tire operation. It is appreciated that the elastomeric material 62 may extend partially or fully across the spoke width W50 (see FIG. 4). Elastomeric material 62 is characterized as having a modulus of elongation (also known as a modulus of elasticity) ranging from 2 to 30 mega pascals (MPa), and may comprise any desired elastomer, including any natural or synthetic rubber, or any blend thereof. [0032] It is appreciated that the elastomeric material 62 may be provided in any form, such as a by way of a pair of pads arranged on opposing radial sides as is generally shown in FIGS. 2 and 3. In other exemplary variations, elastomeric material 62 may be fully arranged around the terminal end 54E, in lieu of employing a pair of pads. It is appreciated that in arranging elastomeric material 62 along the inner hub portion 54, the elastomeric material may be attached to either the inner hub portion 54 or to the inner hub connector 64 if the elastomeric material is attached at all. It is conceived that in lieu of arranging the elastomeric material 62 and resilient joint 60 at a terminal end 54E of the inner hub portion 54, the elastomeric material 62 may be arranged at any desired location along the inner hub portion length L between terminal end 54E and the connecting portion 56.

[0033] With continued reference to FIGS. 2 and 3, an inner hub connector 64 is shown that operates as a clamp, which secures the inner hub portion terminal end 54E together with elastomeric material 62 to the inner hub 40. Optionally, as may be necessary, inner hub connector 64 may also maintain inner hub portion 54 a distance from the inner hub 40 to permit clearance for the spoke 50 to deflect and pivot during tire operation without contacting inner hub 40. Additionally, or in lieu thereof, inner hub 40 may be sized and/or shaped to permit such clearance. For example, the width W40 of the inner hub 40 may be narrowed in the axial direction A _d and/or the lateral sides of the inner hub width W40 may be tapered radially inward, such as is exemplarily shown. In certain instances, the inner hub width W40 may be narrowed in to each inner hub connector 64. In certain instances, inner hub connector 64 is rigid, that is, it is not configured to flex during intended tire operating conditions. Elastomeric material 62 with or without inner hub portion 54 is secured within inner hub connector 64 by any desired manner, such as, without limitation, by use of an adhesive, by pressure (squeezing), by mechanical interference, and/or by fasteners. Inner hub connector 64 is shown affixed to inner hub by use of a fastener 66, such as a bolt, but may be attached using any other manner, such as by weldment. In other instances, inner hub connector 64 is formed as part of inner hub 40. In operating as a clamp, it is appreciated that the aperture within which inner hub portion 54 and elastomeric material 62 is arranged and secured may remain fixed or may be configured to vary in size and/or shape to permit expansion (opening) of the aperture to better receive the material to be secured and to contract (close) the aperture upon the material for application of clamping forces to secure the material therein.

[0034] It is appreciated that opposing spokes may be unitary or separate. For example, in FIG. 2 opposing spokes 50 are shown as forming a single unitary member, where outer band portions 52 are connected to join opposing spokes 50. In such instances, opposing spokes 50 may be monolithically formed (such as is shown), which does not include elastomeric material 62, or may be attached to one another using any known manner, such as by use of weldments, mechanical interference, or fasteners, for example. In other instances, such as is shown in FIG. 5, opposing spokes 50 may be separate.

[0035] With specific reference to FIG. 3, opposing spokes 50 from FIG. 2 are shown in further detail. In particular, spoke thickness t ₅₀ is shown to remain generally uniform along the length L ₅₀ of each spoke 50. In particular instances, spoke thickness t ₅₀ is at least equal 2 mm, while in certain instances the spoke thickness tso ranges from 2 mm to 4 mm. In such instances, a radial pace P _52/54 between the outer band portion 52 and inner hub portion 54, as measured from the radial centerline of the spoke thickness in each of the outer band portion 52 and inner hub portion 54, is at least 40 mm but may range from 40 mm to 80 mm, depending on the dimensions required for any specific application. In such instances, the axial (lateral) span SP ₅₀ of opposing spokes 50 in combination equals at least 155 mm, while in other instances ranges from 155 mm to 350 mm. Additionally, in such instances, the length L ₅₄ of each inner hub portion 54 is 20 to 100 mm. As with outer band portion 52, inner hub portion length L ₅₄ may extend along any desired linear or non-linear path, while in the exemplary embodiment shown, inner hub portion length L ₅₄ extends linearly in the axial direction A _d without extending in either the radial direction R and/or the circumferential direction C _d - Further, in such instances, with reference to FIG. 4, each spoke has a width W ₅₀ equal to 15 mm, but this width W ₅₀ may increase or decrease as is desired to alter the spring stiffness of the tire or tire sidewall. The width may also be dependent on the quantity of spokes arranged in any first or second plurality PI ₅₀ , P2so to ensure that a space remains between adjacent spokes. In such instances, spokes 50 may be formed of any desired material that satisfies the modulus and elastic yield limit requirements during the extension and compression cycles represented in FIGS. 7 and 8. In one exemplary embodiment, spokes 50 are formed of vinyl ester resin reinforced with glass fibers. In certain instances, each spoke 50 has a flexural rigidity of approximately 500,000 Nmm ² , such as when the spoke has a width of 15 mm, and where the material from which it is formed does not reach its yield strength during normal operating conditions. It is appreciated that outside these exemplary instances, other values for these dimensions may be employed for differently sized tires and for tires being exposed to different operating conditions. It is noted that spoke 50 is dimensionally symmetrical about axial centerline CL _A in the embodiment shown.

[0036] As noted previously, with reference to FIG. 2, inner hub portion 54 is flexibly fixed to inner hub 40 at a resilient joint 60. This permits each corresponding spoke 50 to pivot, such as in the radial direction R _d , in the circumferential direction, or, with reference to FIG. 6, in a direction normal to a plane P extending in both the radial direction R and in the axial direction A _d - By permitting each spoke 50 to pivot in this manner relative to the inner hub 40 with spoke deflection, the stresses and strains observed by each spoke 50 are reduced, such as when the spoke undergoes deradialization, for example. Deradialization is the shifting of the outer band portion 52 and the inner hub portion 54 relative to one another in opposite directions due to the application of compressive forces to the tire 10, and therefore each of the tread 20, outer band 30, and spokes 50, in a generally radial direction R _d . In particular, when the tread 20 and outer band 30 are deflected due to a downward force at an area of contact between the tread 20 and a ground surface, which is commonly referred to as a contact patch or footprint, the adjacent portions of the tread and outer band shift away from the footprint centerline in response to outer band inextensibility, thereby causing the outer band portion 30 of a corresponding spoke 50 to also shift away from the footprint centerline and its radial alignment with its inner hub portion 54. This occurs on each side of the footprint. As can be seen in FIG. 6, the outer band portion 52 is shifted away generally in a circumferential direction C _d from its normal radial alignment with its inner hub portion 54 due to deradialization force FDR, where under its normal radial alignment each is aligned radially (that is, in radial direction R _d ) with one another. This normal alignment is shown relative to plane P.

[0037] It is appreciated that the spokes 50 may employ a degree of pre-tension, such as to reduce the amount of stress and strain observed during tire loading, or otherwise to improve any desired tire performance characteristic, such as ride comfort, noise, load carrying capacity, for example. In pre-tensioning any spoke 50, the spoke is deformed and strained in a radial direction R _d from an undeformed arrangement, such as is generally shown in FIG. 7 where each inner hub portion 54 is deflected outwardly by way of force F _T . Thereafter, typical deflection of the spoke under common loading conditions observed during normal tire operation is shown in FIG. 8, where inner hub portions 54 are each deflected by force Fc (a compressive force) inwardly relative the spoke 50 but radially outward relative to the tire.

[0038] For passenger car and light truck tires, it is anticipated that at least 30 spokes 50 may be included within an annular array for each plurality of spokes PI50, P2so. It is generally appreciated that when the quantity of spokes 50 is increased for any given non-pneumatic tire 10 or tire carcass, whereby the spacing between adjacent spokes decreases, such tire or tire carcass is characterized as being stiffer (having a higher spring rate) and having a greater load capacity. The contrary is also true, meaning, that when the quantity of spokes 50 is decreased for the same non-pneumatic tire 10 or tire carcass, whereby the spacing between adjacent spokes increases, such tire or tire carcass is characterized as being softer (having a lower spring rate) and having a reduced load capacity. Without altering the quantity of spokes 50, increases and decreases in stiffness may be achieved by altering the dimensions of each spoke, as well as altering the material(s) used to form each spoke.

[0039] 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.

[0040] 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.