Patent Publication Number: US-2023144132-A1

Title: Nonpneumatic tire and wheel assembly

Description:
FIELD OF THE INVENTION 
     The invention relates in general to a vehicle wheel, and more particularly to a nonpneumatic tire and wheel assembly. 
     BACKGROUND OF THE INVENTION 
     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 dominate 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 is desired that has all the features of the pneumatic tires without the drawback of the need for air inflation is desired. It is also desired to have an improved nonpneumatic tire that has longer tread life as compared to a pneumatic tire of the same size. 
     Definitions 
     “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. 
     “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. 
     “Circumferential” means lines or directions extending along the pewheeleter 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. 
     “Radial” and “radially” mean directions radially toward or away from the axis of rotation of the tire. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described by way of example and with reference to the accompanying drawings in which: 
         FIG.  1    is a front view of a nonpneumatic tire and wheel assembly of the present invention; 
         FIG.  2    is a cross-sectional view of the nonpneumatic tire and wheel assembly of  FIG.  1   ; 
         FIG.  3    is a close-up front view of a portion of the spoke ring assembly; 
         FIG.  4    is an exploded view of the nonpneumatic tire and wheel assembly of  FIG.  1   ; 
         FIG.  5    is a cross-sectional view of one half of the nonpneumatic tire and wheel assembly of  FIG.  1   ; 
         FIG.  6    is a close-up cross-sectional view of the spoke structure of the nonpneumatic tire and wheel assembly of  FIG.  1   ; 
         FIG.  7    is a cross-sectional perspective view of the spoke structure and tread; 
         FIG.  8 A  is a side view of the outboard spoke ring, while  FIG.  8 B  is a perspective side view of the outboard spoke ring of  FIG.  8 A ; 
         FIG.  9 A  is a side view of the middle spoke ring, while  FIG.  9 B  is a perspective side view of the middle spoke ring of  FIG.  9 A ; 
         FIG.  10 A  is a side view of the outboard spoke ring, while  FIG.  10 B  is a perspective side view of the outboard spoke ring of  FIG.  10 A ; and 
         FIG.  11    is a cross-sectional view of a shearband of the nonpneumatic tire and wheel assembly of  FIG.  1   . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS.  1  through  10   , a nonpneumatic tire and wheel assembly  10  of the present invention is shown. The nonpneumatic tire and wheel assembly  10  includes an outer annular tread ring  30 , a spoke ring  20 , and a wheel  50 . The outer annular tread ring  30  is preferably a one piece annular structure that is formed of a polymer, rubber or other desired elastomer. The tread ring  30  may be molded and cured as a one piece ring, and is mounted on the outer periphery of the spoke ring. The outer tread surface  31  of the tread ring  30  may include tread elements such as ribs, blocks, lugs, grooves, and sipes as desired in order to improve the performance of the tire in various conditions. 
     The shear band  31  is preferably an annular structure that is located radially inward of the tire tread  30  and functions to transfer the load from the bottom of the tire which is in contact with the ground to the spokes and to the hub, creating a top loading structure. The annular structure  31  is called a shear band because the preferred form of deformation is shear over bending. 
     A first embodiment of a shear band  31  is shown in  FIG.  11   . The shear band may include a first, second and third reinforcement layer  32 ,  33 ,  36 . Each reinforcement layer is formed of a plurality of closely spaced parallel reinforcement cords. The parallel reinforcement cords may be formed from a calendared fabric so that the reinforcement cords are embedded in a elastomeric coating. Preferably, each reinforcement layer  32 , 33 , 36  is formed from spirally winding a single end cord. Preferably, the single end cord has multiple filaments. 
     The first and second reinforcement layers  320 , 330  are preferably the radially innermost reinforcement layers of the shear band  300 , and the second reinforcement layer  330  is located radially outward of the first membrane layer. The third reinforcement layer  360  is located radially outward of the second reinforcement layer  33 . The inextensible reinforcement cords of each layer  32 , 33 ,  36  are preferably angled in the range of five degrees or less with respect to the tire equatorial plane. The reinforcing cords of the first and second reinforcement layers  32 , 33  may be suitable tire belt reinforcements, such as monofilaments or cords of steel, aramid, and/or other high modulus textiles. For example, the reinforcing cords may be steel cords of four wires of 0.28 mm diameter (4 x 0.28) or 0.22 mm diameter. In another example, the reinforcing cords may be steel cords of 6 wires, with five wires surrounding a central wire (5 +1) construction. 
     The third reinforcement layer  36  is separated from the second reinforcement layer  33  by a first shear layer  35 . The shear band  31  further comprises a second shear layer  37  located radially outward of the third reinforcement layer  36 . The first and second shear layer  35 , 37  is formed of an elastomer or rubber having a shear modulus in the range of 3 MPa to 30 MPa, or more preferably in the range of 10 MPa to 20 MPa. The shear modulus is defined using a pure shear deformation test, recording the stress and strain, and determining the slope of the resulting stress-strain curve. 
     The shear band  31  further includes a first angled belt  38  and a second angled belt  39 . The first angled belt  38  is located radially outward of the second shear layer  37 , and the second angled belt  39  is located radially outward of the first angled belt  380 . The first and second angled belts  380 ,  390  each have parallel reinforcement cords that are embedded in an elastomeric coating. The parallel reinforcement cords are preferably angled in the range of  15  to 30 degrees with respect to the tire equatorial plane. Preferably, the angle of the parallel reinforcement cords is in the range of 20-25 degrees. Preferably, the angle of the reinforcement cords of the first angled belt is in the opposite direction of the angle of the reinforcement cords in the second angled belt. It is additionally preferred that the reinforcement cords are inextensible. 
     The shear band has an overall shear stiffness GA. The shear stiffness GA may be determined by measuring the deflection on a representative test specimen taken from the shear band. The upper surface of the test specimen is subjected to a lateral shear force F. The test specimen is a representative sample taken from the shear band and having the same radial thickness as the shearband. The shear stiffness GA is then calculated from the following equation: GA=F*L/ΔX, where F is the shear load, L is the shear layer thickness, and ΔX is the shear deflection. It is preferred that GA be in the range of about 15,000 N to 35,000 N, and more preferably, about 25,000 N. 
     The shear band has an overall bending stiffness EI. The bending stiffness EI may be determined from beam mechanics using the three point bending test. It represents the case of a beam resting on two roller supports and subjected to a concentrated load applied in the middle of the beam. The bending stiffness EI is determined from the following equation: EI = PL3/48* ΔX, where P is the load, L is the beam length, and ΔX is the deflection. It is preferred that EI be in the range of 270 E6 N-mm2 plus or minus 25%. 
     Spoke Ring Structure 
     The nonpneumatic tire and wheel assembly  10  further includes a spoke structure  20 . The spoke structure  20  has at least one layer of spoke rings  22 , and preferably at least two spoke rings  22 , 24 .  FIGS.  4 - 5    illustrates a nonpneumatic tire and wheel assembly having three spoke rings  22 , 24 , 26 . 
     Each spoke ring  22 , 24 , 26  may be an integrally formed ring or may be formed from a plurality of sectors  22   a  that are assembled to form a ring  22 .  FIG.  8   a    illustrates a sector  22   a  used to form the spoke ring  22 . There are 6 sectors used to form the spoke ring  22 , although there may be more or less sectors to form the ring. As shown in  FIG.  8   b   , the spoke ring  22  is the outboard spoke ring that faces axially outward when mounted on a vehicle. The spoke ring  22  has a plurality of X shaped spokes formed from a first spoke member  60  that is joined to a second spoke member  62 . The first and second spoke member  60 , 62  are joined together at a junction  70  to form an X shaped spoke. The first and second spoke members  60 , 62  may be straight or curved. The number of spokes may vary, for example, from  15  to  60  depending upon the vehicle weight and desired spring rate. The outboard spoke ring has an axially outer edge  64  that is radiused. The outboard spoke ring  22  has an axially inner edge  66  that is not radiused, and is straight in the radial direction. The outer tread ring  30  extends axially outward of the center disk  52  of the wheel, so that the wheel is recessed to reduce noise. 
       FIG.  10 A  illustrates a sector of the inboard spoke ring  26 . The inboard spoke ring  26  is the same as the spoke ring  22 , except for the following differences. The axially outer edge  74  of the inboard spoke ring  26  is radiused, while the axially inner edge  72  is straight, or aligned with the radial direction. 
       FIG.  9 A  illustrates a sector of the middle spoke ring  24 . The middle spoke ring  24  is the same as the spoke ring  22 , except for the following differences. The axially outer edge  68  and axially inner edge  70  of the middle spoke ring  24  is straight, or aligned with the radial direction. Additionally, as shown in  FIG.  7   , the middle spoke ring is clocked so that it is not in alignment with the X spokes of spoke rings  22  or  26 . 
     Each spoke ring  22 , 24 , 26  has an inner portion  21  that is mounted on the wheel rim mounting surface  53 , and an outer portion  27  that is connected to the inner surface of the tread ring. Preferably, the inner portion  21  has an interference fit on the outer rim mounting surface  53  of the wheel  50 . 
     The radius R of the radiused outer edges may range from 1 to 2 inches. The scalloped or radiused outer edges allow the wheel to be recessed axially inward of the spoke and tread ring structure. 
     The spoke ring structures  22 , 24 , 26  are preferably made of a resilient and/or moldable polymeric material such as but not limited to, a thermoplastic elastomer, natural rubber, styrene butadiene rubber, polybutadiene rubber or EPDM rubber or a blend of two or more of these materials which can be utilized in either injection molding or compression molding. The material of the spoke ring structure is selected based upon one or more of the following material properties. The tensile (Young’s) modulus of the spoke disk material is preferably in the range of 5 MPa to 100 MPa, and more preferably in the range of 10 MPa to 70 MPa. 
     The wheel  50  is best shown in  FIG.  4   , and has an annular outer rim mounting surface  53  for receiving the inner portion  21  of each of the spoke ring structures  22 , 24 , 26 . The wheel further includes a recessed center disk  52  having a plurality of bolt holes  54  for connecting the wheel assembly to a vehicle. The center disk is mounted to an outer flange  56  via a plurality of bolts  58 . The wheel is preferably formed of powder coated aluminum. 
     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.