Non-pneumatic suspension tire

Abstract

A non-pneumatic tire for a vehicle wheel comprising a resilient tread ring, a mounting ring attached to the wheel rim and a plurality of resilient corrugated rings disposed between the two rings. The corrugated rings have convex and concave curvatures and are angularly aligned to each other. All the rings are attached with discrete spacer mounts, disposed circumferentially in an angularly misaligning fashion. The structural tire enables vertical vehicle forces to transform into tangential forces acting on the tread ring providing suspension of the tire.

Description

NON-PNEUMATIC SUSPENSION TIREFIELD OF INVENTION

[0001] The present invention relates to anon-pneumatic tire for vehicle wheels. More particularly, this invention pertains to structural tires, which provide improved vehicle suspension and reduced rolling energy losses.BACKGROUND OF THE INVENTION

[0002] The pneumatic tire is presently used universally as a peripheral part of a vehicle wheel. The disadvantages of pneumatic tires are sensitivity of performance to air pressure, susceptibility to damage, rolling energy losses due to viscoelastic tire material, noise, poor recyclability, and cumbersome replacement of the tire. Energy deficiencies of the pneumatic tire are particularly acute for bicycle tires where propelling energy is at a premium. Cushioning capability of a pneumatic tire is limited, especially, since an improvement cannot be achieved without increasing the rolling energy losses.Non-pneumatic tires have the inherent advantage of being puncture-proof as well as a promise of relatively stable energy-efficient operation. They could be also easier to mount on the wheel and provide better axial stiffness improving the cornering of a vehicle. Historically, the development of resilient non-pneumatic tires generated a substantial number of ideas, however without a clear winner. Published inventions employ various designs of springs, spokes, and viscoelastic squashable structures to transfer the forces applied by the mass of the vehicle to the ground, mainly in the radial direction of the wheel. Load-carrying components typically act as compression springs or as tension components buckling at contact with the ground. The components of the present non-pneumatic tires may experience significant deflections which result in stress concentrations, vibration, and material fatigue problems. A substantial improvement in wheel suspension and a reduction of rolling energy losses are not demonstrated.SUMMARY OF THE INVENTION

[0003] Accordingly, one object of the present invention is to create a dependable nonpneumatic tire for the vehicle wheel with improved suspension and reduced rolling energy losses.

[0004] The non-pneumatic suspension tire comprises a resilient tread ring, a mounting ring, and a plurality of resilient corrugated rings sequentially disposed between the two rings. Resiliency is defined as the capability to spring back from a deformed shape. Each ring has an axis coinciding with the axis of rotation of a vehicle wheel. The outer face of the tread ring is carrying a tread band that is in contact with the ground during the rolling of the wheel. The corrugated rings are arranged in sequence with the ring having a larger diameter abutting the tread ring and the ring having a smaller diameter abutting the mounting ring. The corrugated rings have convex curvatures and concave curvatures disposed altematingly and circumferentially around the axis circumferentially. The curvatures are angularly aligned so that the convex curvatures and the concave curvatures of one corrugated ring fit the respective curvatures of another ring. The wheel rolling forces are transmitted from the tread ring to the mounting ring through discrete spacer mounts connecting the corrugated rings among themselves, to the tread ring, and the mounting ring in an angularly misaligning fashion. The application of the corrugated rings as load-transmitting components results in a minimal load resistance of the tire in the wheel's radial direction at the contact with the ground. The vehicle load forces are transferred away from the contact to the ground into the wheel's tangential direction forcing the tread ring to bend and bulge on each side of the contact, providing suspension. The function of the convex and concave curvatures of the corrugated rings is to provide elasticity of the tire in the wheel's tangential direction. The advantage is a more uniform distribution of stress and less vibration. Since the rings of the non-pneumatic tire can be made from resilient elastic material with low hysteresis a lower rolling energy loss of the wheel is achievable. Another advantage is that the radius of the tread ring in the vicinity of the contact with the ground increases which improves cushioning of the wheel since it smoothens the rolling fluctuations caused by unevenness of the ground surface.

[0005] This summary of the invention does not necessarily describe all features of the invention. In the following, the invention will be described in detail with reference to the drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a front view of the non-pneumatic suspension tire mounted to the vehicle wheel according to this invention. The lower portion of the tire is touching the ground and is showing deformation by applying a vehicle load.

[0007] Figure 2 is a perspective view of the enlarged cutaway section of the embodiment shown in Figure 1.

[0008] Figure 3 is a front view of a section of the embodiment shown in Figure 1.

[0009] Figure 4 is a front view of a section of an alternative embodiment according to this invention wherein the corrugated rings have additional curvatures between the spacer mounts.

[0010] Figure 5 is a front view of a section of an alternative embodiment according to this invention wherein the corrugated rings have a reduced number of curvatures between the spacer mounts.

[0011] Figure 6 is a front view of a section of an alternative embodiment according to this invention including 4 corrugated rings.

[0012] Figure 7 is a front view of a section of another alternative embodiment according to this invention showing small radii of convex and concave curvature of the first corrugated ring and large radii of convex and concave curvature of the last corrugated ring.

[0013] Figure 8 is a perspective view of the enlarged cutaway section of another embodiment according to this invention where the mounting ring is provided with a flange fastened to the wheel rim.

[0014] Figure 9 is a perspective view of the enlarged cutaway section of another embodiment according to this invention wherein the separating mounts extend partially along the width of the tire.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The non-pneumatic suspension tire according to this invention is illustrated in Figures 1, 2, and 3. The tire is mounted to the vehicle wheel having rim 1, spokes 2, and hub 3. The tire has width 4 and comprises the resilient tread ring 5, mounting ring 6, and two corrugated rings, ring 7 and ring 8. Resiliency is defined as the capability to spring back from a deformed shape. The corrugated rings are disposed in the annular space 9 between the inner face 10 of the tread ring 5 and the outer face 11 of the mounting ring 6. The axis of the tread ring, mounting ring, and each corrugated ring coincide with the rotational axis 12 of the wheel. The tread ring 5 is on the outer face 13 provided with tread band 14, which is preferably made from an elastomeric material, and which is in contact with the surface of the ground 15, during the rolling of the wheel. The mounting ring 6 has inner face 16 which is abutting rim 1. The provision of the mounting ring in this example of the non-pneumatic suspension tire has the purpose of allowing the complete tire to be separated from the wheel. Fusing the wheel and the tire into a single component can be also envisioned without departing from the functionality of the non-pneumatic suspension tire.

[0016] The corrugated rings have different diameters and are disposed sequentially according to the diameter. The first corrugated ring 7 has the largest diameter and is spaced at the radial distance 17 from the tread ring. The last corrugated ring 8 has the smallest diameter and is spaced at the radial distance 18 from the mounting ring.

[0017] Corrugations of each corrugated ring are provided by convex curvatures and by concave curvatures applied circumferentially and altematingly around axis 12. The curvature is defined by a radius and the axis which is parallel to the axis 12 of the wheel. In the example shown in Figure 3, the convex curvature has radius 19 of the outer face 30 of the first corrugated ring 7, and axis 20. The concave curvature has radius 21 of the outer face 30 of the first corrugated ring 7 and axis 22. The corrugations of different corrugated rings are angularly aligned with each other. Corrugated ring 7 is angularly aligned with corrugated ring 8 by aligning its convex curvature 23 with the respective convex curvature 24 of the corrugated ring 8 at angle 25. Similarly, concave curvature 26 of ring 7 is aligned with the respective concave curvature 27 of ring 8 at angle 28.

[0018] The rings comprising the non-pneumatic suspension tire are attached by discrete spacer mounts disposed sequentially and circumferentially around axis 12 and extending inthe direction of axis 12 along width 4 of the tire. Figure 3 shows a plurality of spacer mounts 29 which attach the inner face 10 of the tread ring 5 to the outer face 30 of the first corrugated ring 7. The spacer mounts provide radial space 17 between the rings to allow room for the deflection of the rings. The attachment between the corrugated rings 7 and 8 is achieved using spacer mounts 31 attaching the outer face 32 of ring 8 to the inner face 33 of ring 7. The spacer mounts 31 provide radial space 34 between the corrugated rings. Spacer mounts 35 are provided to attach corrugated ring 8 to the mounting ring 6 providing radial space 18.

[0019] Another function of the spacer mounts is to transfer forces between the rings. A convenient attachment of the first corrugated ring to the tread ring is to include three convex curvatures between the adjacent spacer mounts 29. To allow bending of the portion of the corrugated ring between the adjacent spacer mounts the location of spacer mount 31 on the inner face of ring 7 is angularly misaligned relative to spacer mount 29 on the outer face of ring 7 by angle 36. Similarly, spacer mounts 35 are angularly misaligned with spacer mounts 31. This arrangement of the spacer mounts provides uniform stress of the corrugated rings during the rolling of the wheel.

[0020] During rolling the non-pneumatic suspension tire incorporating corrugated rings experiences very small load resistance in the wheel radial direction 36 at the contact to the ground 15. The vehicle load-carrying forces are mainly acting in the wheel's tangential directions. At the contact with the ground, the tangential forces are acting in directions 37 and 38. At a distance from the contact to the ground the tangential forces are acting in directions 52 and 53. The tangential forces are deforming the tread ring 5 into bulges 39 and 40. The section of the tread ring between bulges 39 and 40 acts like a simply supported beam loaded in bending. However, the tangential forces 52 and 53 are carrying vehicle load by the corrugated rings directly since they are coinciding with direction 36. Tread ring bending and corrugated ring bending are jointly providing tire suspension. An additional advantage of tread ring deformation between the bulges is that it assumes a larger radius than the outside radius of the tire. This is beneficial to the rolling smoothness.

[0021] The preferred embodiment of the invention described above is suitable for injection molding or fiber composite manufacturing. Engineering design involving material and geometry would determine the performance of the non-pneumatic suspension tire. However, other arrangements or forms of corrugated rings would also achieve the desired performance. Figure 4 shows corrugated rings with additional curvature between the spacer mounts. Thisfeature may allow a more compact design. Figure 5 shows only two convex curvatures 52 and one concave curvature 53 between the spacer mounts. Such a reduced number of curvatures may allow a better fit for a smaller diameter wheel. Figure 6 shows four corrugated rings rather than two. An increased number of rings would allow larger radial deflections of the tire resulting in a “softer” ride and more forgiving of the ground unevenness. Figure 7 shows an alternative embodiment where the radius of curvature 41 of the first corrugated ring is the smallest and the radius 42 belonging to the third corrugated ring is the largest. This feature may allow a more compact design.

[0022] The mounting ring of the non-pneumatic suspension tire allows for easy replacement of the complete tire. An example of mounting the tire to a narrow-width wheel such as a bicycle wheel is shown in Figure 8. The mounting ring of the tire is provided with flange 43 which abuts rim surface 44 of the wheel rim 1. The inner face 45 of the mounting ring fits the outer face 46 of the rim. The tire is mounted by fitting the tire mounting ring to the wheel rim and by fastening the flange 43 to surface 44 using screws 47.

[0023] In the case of the application of a non-pneumatic suspension tire according to this invention to a wider wheel such as the car wheel the structural composition of the tire offers unique advantages in comparison to the pneumatic tire. The small radial thickness 48 of the tire as shown in Figure 8 is particularly favorable to the non-pneumatic tire since it allows for a larger diameter of the wheel rim. The wider wheel also allows the spacer mounts 49 to be shorter than the width 50 of the tire. Several spacer mounts with separation 51 can be deposited in the same row in the wheel axial direction. This arrangement of spacer mounts may result in a more uniform stress distribution of the tire.

Claims

WHAT IS CLAIMED IS:

1. A tire for a vehicle wheel having a rim and a rotational axis, said tire having a width and comprising: a resilient circular tread ring having an axis coinciding with the rotational axis, the tread ring having an inner face with respect to the axis, and a mounting ring having an axis coinciding with the rotational axis, the mounting ring having an outer and an inner face, the inner face of the mounting ring abutting said rim, and two or more resilient corrugated rings, each said corrugated ring having an axis coinciding with the rotation axis and sequentially disposed between the tread ring and the mounting ring, each corrugated ring having an outer face and an inner face, wherein: each said corrugated ring has a different diameter, first corrugated ring has the largest diameter and is radially spaced from the inner face of the tread ring, each sequential corrugated ring has a smaller diameter and is radially spaced from the corrugated ring with a larger diameter, last corrugated ring has the smallest diameter and is radially spaced from the outer face of the mounting ring, and each corrugated ring is characterized by convex curvatures and by concave curvatures disposed altematingly and circumferentially around the corrugated ring axis, where the convex and the concave curvatures of one corrugated ring align angularly with the respective curvatures of another corrugated ring, and the rings are attached with discrete spacer mounts extending in the direction of the rotational axis, said mounts sequentially and circumferentially disposed around said axis, one or more of said convex and said concave curvatures of the corrugated ring included circumferentially between adjacent spacer mounts, and where spacer mounts disposed on the outer face of the corrugated ring are angularly misaligned relative to the spacer mounts disposed on the inner face of the same corrugated ring.

2. The tire according to claim 1, wherein said convex curvature and said concave curvatures are respectfully defined by a radius, where said radius belonging to the first corrugated ring is the smallest and the radius belonging to the last corrugated ring is the largest.

3. The tire according to claim 1, wherein the inner face of the mounting ring is provided with a flange, said flange enabled to fasten to the rim of the wheel.

4. The tire according to claim 1, wherein the spacer mounts extending in the wheel axial direction are shorter than the width of the tire.