Patent Application
20220185016
The present invention relates generally to vehicle tires, and more particularly, to a non-pneumatic tire.
The pneumatic tire has been the solution of choice for vehicular mobility for over a century. The pneumatic tire is a tensile structure. The pneumatic tire has at least four characteristics that make the pneumatic tire so dominant today. Pneumatic tires are efficient at carrying loads because all of the tire structure is involved in carrying the load. Pneumatic tires are also desirable because they have low contact pressure, resulting in lower wear on roads due to the distribution of the load of the vehicle. Pneumatic tires also have low stiffness, which ensures a comfortable ride in a vehicle. The primary drawback to a pneumatic tire is that it requires compressed fluid. A conventional pneumatic tire is rendered useless after a complete loss of inflation pressure.
A tire designed to operate without inflation pressure may eliminate many of the problems and compromises associated with a pneumatic tire. Neither pressure maintenance nor pressure monitoring is required. Structurally supported tires such as solid tires or other elastomeric structures to date have not provided the levels of performance required from a conventional pneumatic tire. A structurally supported tire solution that delivers pneumatic tire-like performance would be a desirous improvement.
Non pneumatic tires are typically defined by their load carrying efficiency. “Bottom loaders” are essentially rigid structures that carry a majority of the load in the portion of the structure below the hub. “Top loaders” are designed so that all of the structure is involved in carrying the load. Top loaders thus have a higher load carrying efficiency than bottom loaders, allowing a design that has less mass.
Thus, an improved non pneumatic tire that has all the features of the pneumatic tires without the drawback of the need for air inflation is desired.
The invention provides in a first aspect a non-pneumatic tire and wheel assembly including a wheel having a first and second bead ring, a non-pneumatic tire having a shear band and tread forming a tread band, and a first and second sidewall region; wherein the first and second sidewall regions each extend from the tread band and terminate into a first and second respective bead area, wherein the first and second bead area are each mounted on the first and second bead ring, respectively; wherein each bead area is located axially outward of the crown region of the non-pneumatic tire when mounted on the wheel, and wherein the first and second sidewall each have an upper sidewall region that is uncoupled from the outer lateral ends of the tread band.
The present invention will be better understood through reference to the following description and the appended drawings, in which:
“Aspect Ratio” means the ratio of a tire's section height to its section width.
“Axial” and “axially” means the lines or directions that are parallel to the axis of rotation of the tire.
“Bead” or “Bead Core” means generally that part of the tire comprising an annular tensile member, the radially inner beads are associated with holding the tire to the rim being wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes or fillers, toe guards and chafers.
“Belt Structure” or “Reinforcing Belts” means at least two annular layers or plies of parallel cords, woven or unwoven, underlying the tread, unanchored to the bead, and having both left and right cord angles in the range from 17° to 27° with respect to the equatorial plane of the tire.
“Breakers” or “Tire Breakers” means the same as belt or belt structure or reinforcement belts.
“Carcass” means a laminate of tire ply material and other tire components cut to length suitable for splicing, or already spliced, into a cylindrical or toroidal shape. Additional components may be added to the carcass prior to its being vulcanized to create the molded tire.
“Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction; it can also refer to the direction of the sets of adjacent circular curves whose radii define the axial curvature of the tread as viewed in cross section.
“Cord” means one of the reinforcement strands, including fibers, which are used to reinforce the plies.
“Inextensible” means a cord having a relative elongation at break of less than 0.2% at 10% of the breaking load, when measured from a cord extracted from a cured tire.
“Equatorial Plane” means a plane perpendicular to the axis of rotation of the tire passing through the centerline of the tire.
“Meridian Plane” means a plane parallel to the axis of rotation of the tire and extending radially outward from said axis.
“Ply” means a cord-reinforced layer of elastomer-coated, radially deployed or otherwise parallel cords.
“Radial” and “radially” mean directions radially toward or away from the axis of rotation of the tire.
“Radial Ply Structure” means the one or more carcass plies or which at least one ply has reinforcing cords oriented at an angle of between 65° and 90° with respect to the equatorial plane of the tire.
“Radial Ply Tire” means a belted or circumferentially-restricted pneumatic tire in which the ply cords which extend from bead to bead are laid at cord angles between 65° and 90° with respect to the equatorial plane of the tire.
“Sidewall” means a portion of a tire between the tread and the bead.
“Laminate structure” means an unvulcanized structure made of one or more layers of tire or elastomer components such as the innerliner, sidewalls, and optional ply layer.
As shown in
In a first embodiment of a shear band 300, the shear band is comprised of at least two inextensible reinforcement layers 310,320 arranged in parallel, and separated by a shear matrix 315 of elastomer. Each reinforcement layer 310,320 may be formed of parallel reinforcement cords embedded in a thin elastomeric coating. The reinforcement cords are preferably inextensible, and may be made of steel, aramid, nylon, polyester, or other inextensible structure. In the first reinforced elastomer layer 310, the reinforcement cords are oriented at an angle in the range of 0 to about +/−50 degrees relative to the tire equatorial plane, and more preferably in the range of 0 to +/−10 degrees. In the second reinforced elastomer layer 320, the reinforcement cords are oriented at an angle in the range of 0 to about +/−50 degrees relative to the tire equatorial plane, more preferably 0 to +/−10 degrees. Preferably, the angle of reinforcement cords of the first layer is in the opposite direction of the angle of the reinforcement cords in the second layer. As shown, the shear band 300 may further optionally include as many additional reinforcement layers 330-360 to achieve the desired stiffness. It is additionally preferred that the radially outermost reinforcement layers 350,360 have outer lateral ends 351,361 having a reduced axial width as compared to the radially inner reinforcement layers 310-340.
The shear matrix layer 315 located between the first and second reinforcement layer 310,320 and is formed of an elastomer material having a shear modulus Gm in the range of 0.5 to 10 MPa, and more preferably in the range of 4 to 8 MPA. The thickness of the rubber layer 315 may have a radial thickness in the range of about 0.10 inches to about 0.2 inches, more preferably about 0.15 inches. If additional reinforcement layers 330-360 are utilized, the reinforcement layers may also be optionally separated by the shear layer 315. The belt package together with the shear layer form a shear band. The shear band together with the tread form an outer annular tread band.
As shown in
The radially innermost end 410 of each sidewall preferably includes an annular bead 420 which is secured to the wheel. The non-pneumatic tire 100 further includes a first layer of ply 500 which extends from the first bead 420 to the second bead 422. Preferably, the ply 500 comprises a reinforced rubber or ply layer formed of parallel reinforcement cords that are nylon, polyester, aramid or formed of a merged cord of nylon, polyester of aramid. Preferably, the reinforcements are oriented in the radial direction. The layer of ply extends radially inward from the tread, and is then wrapped around the first bead 420 and has a first end 510 that preferably terminates underneath the shear band 300 forming an envelope ply. A second end 520 of the ply likewise extends down from the tread, is wrapped around the opposite bead 420, and then terminates preferably underneath the shear band forming an envelope ply. Thus, each sidewall preferably has two effective layers of ply. Alternatively, the first and second ends 510,520 may wrap around the bead and terminate radially outward of a tip 432 of an apex 430.
Each apex 430 is preferably triangular in shape, and has a radial height as measured from the first end 431 to the tip 432. The radial height of the outer tip 432 is preferably in the range of ¼ to ¾ of the sidewall radial height, and more preferably in the range of ⅓ to ⅔ of the sidewall radial height. Each lower sidewall region which is defined as the lower half of the sidewall, is preferably stiffer relative to the stiffness of the upper half of the sidewall. The lower sidewall may be increased in stiffness by a stiff apex, or additional stiff material in the lower sidewall region such as a chafer or rim flange protector. The additional stiff material may be located on the axially outer portion of the lower sidewall, such as a rim flange protector or a chafer, or an axially inner portion such as a secondary apex.
The stiffness, which is the resistance to bending, may be characterized by the dynamic modulus G′, which are sometimes referred to as the “shear storage modulus” or “dynamic modulus,” reference may be made to Science and Technology of Rubber, second edition, 1994, Academic Press, San Diego, Calif., edited by James E. Mark et al, pages 249-254. The shear storage modulus (G′) values are indicative of rubber compound stiffness which can relate to tire performance. The tan delta value at 100° C. is considered as being indicative of hysteresis, or heat loss.
In a first embodiment, the first apex 430 comprises a stiff rubber composition having a shear storage modulus G′ measured at 1% strain and 100° C. according to ASTM D5289 ranging from 14 to 43 MPa. In a more preferred embodiment, the first apex 430 comprises a rubber composition having a shear storage modulus G′ measured at 1% strain and 100° C. according to ASTM D5289 ranging from 23 to 43 MPa.
The stiffened lower sidewall ensures that the ply is in tension after being mounted on the wheel, and also during use. When the ply and sidewall of the tire is in the relaxed state, the plyline is curved so that the beads are located axially inward of the shoulders of the tire. When the beads are loaded onto the rim, the curve is straightened and the bead or lower sidewall of the tire is moved axially outwards while still preferably remaining within the axial width of the tire shoulders, so that the ply acts as a spring.
As shown in
The stiffness of each sidewall, and more preferably, the lower half of the sidewall contributes to the top loading of the non-pneumatic tire. The lower half of each sidewall is preferably stiff, and may be stiffened due to a stiff apex, and/or a stiff mass of material located on the axially outer portion such as a chafer or rim flange protector. The sidewalls of the tire were pretensioned by axially expanding the wheel rim. In a third embodiment, a chafer or rim flange protector located axially outward of the apex comprises a stiff rubber composition having a shear storage modulus G′ measured at 1% strain and 100° C. according to ASTM D5289 ranges from 14 to 43 MPa, and more preferably from 23 to 43 MPa.
Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.
| Number | Date | Country | |
|---|---|---|---|
| 63126201 | Dec 2020 | US |
