Non-Pneumatic Tire Wheel

This invention relates to a non-pneumatic tire wheel structure and more particularly to a light-weight wheel structure that is non-pneumatic yet has resilient capabilities and the ability to sustain severe damage, impact loading as for use on helicopters.

Heretofore, helicopters have used skids and relied essentially on the lifting ability of the rotating blades. However, it since has been found that the use of pneumatic tires providing a forward rolling action enhanced the ability of the helicopter to take off. The present invention is directed to a non-pneumatic tire wheel structure which can sustain severe damage yet operate as a direct replacement of the pneumatic tire thereby eliminating the vulnerability thereto under adverse battle field conditions. Where a tire is damaged there is a severe restriction on the mobility of the helicopter as the craft is tilted, resulting in also tilting the rotating blades which greatly restrict access to the craft and where unnoticed because of the partial tilting can inflict grave and serious injury to personnel. The tire wheel of the present invention assures the needed weight reduction capabilities that is essential as well as providing for the necessary energy absorption capabilities under impact loading situations. In addition, the non-pneumatic wheel-tire provides for the needed load-carrying requirements where such wheel-tire is a direct replacement of the pneumatic tire heretofore used on the specific craft thereby maintaining an economic benefit of direct replacement.

The invention is directed to a non-pneumatic tire wheel made from a composite material that is toroidal in shape for replacement of an inflatable tire having an annular carcass that is yieldable. The sidewalls of the carcass have a plurality of circumferentially spaced slots that define rigid beam members that yield under load and impact, with the outermost crown portion of the toroidal tire wheel having a rigid ring and an elastomeric tread or tread ring for ground engaging effect. A shock absorbing member is mounted within the carcass connected to an annular hub of the tire wheel to enhance resiliency and shock impact loading of the tire wheel.

For the purpose of illustrating this invention, reference will henceforth be made to the drawings the forms which are presently preferred; however, it should be understood that the invention is not necessarily limited to the precise arrangements as the drawings and the embodiment described is merely illustrative of the invention.

FIG. 1 is a perspective view illustrating one half of the tire wheel structure of the present invention without the tread applied;

FIG. 2 is a perspective view of the tire wheel structure showing the wheel and tire carcass with a portion of the tread and belt structure cut away to illustrate the supporting structure;

FIG. 3 is a cross-sectional view of the tire wheel structure taken on line 3--3 of FIG. 2 shown mounted on the axle of a vehicle;

FIG. 4 is a side elevational view of the tire wheel structure seen in FIG. 3 taken on line 4--4 thereof, with a portion of the tread, belt and body structure broken away;

FIG. 5 is a front elevational view of the tire wheel structure shown in FIG. 4 with the tread and belt broken away and taken on line 5--5 of FIG. 4;

FIG. 6 is a side elevational view of the tire wheel structure as seen in FIG. 4 but under load and additionally supported by a shock absorber;

FIG. 7 is a front elevational view of the tire wheel structure taken on line 7--7 of FIG. 6;

FIG. 8 is a front elevational view of a tire wheel structure similar to FIG. 7 but with a modified shock absorber means.

Referring now to the drawings, wherein like references numerals designate like or corresponding parts throughout the several views, there is shown in FIGS. 2 and 3 a tire wheel 10 mounted on an axle 11.

Tire wheel 10 has an annular hub 12 which has a through hole 13 for receiving the axle 11 and a plurality of circumferentially spaced bores 14. Bores 14 receive threaded fasteners 15 for fastening the hub 12 to an annular carcass 18 of the tire wheel 10. The carcass is the main structural component of the tire wheel other than the hub 12 and the tread to be described.

The carcass 18 is made from a glass fiber reinforced plastic or a graphite epoxy composite material of woven fabric layered composite. Carcass 18 has a pair of axially spaced web portions 19 and 20 which are essentially flat annular plates or sections that merge at their outer radial peripheries with C-shaped portions of the carcass which define the spaced rigid sidewalls 21 and 22 of the tire wheel 10. In the conventional pneumatic tires, the shoulder of a tire is the outer radial portion that merges with the crown of the tire, which is an annular outer portion of the tire. In the non-pneumatic tire wheel of the described embodiment, the uppermost circumferential radial portions of each sidewall has axially spaced annular shoulder portions or shoulders 24 and 25 that merge with an annular circumferentially extending crown 28. The outermost circumferential surface of crown 28 has a ring 29 made of similar rigid composite material. An elastomeric tread 31 is suitably adhered to the ring 29 with its respective side portions merging with the shoulders 24 and 25. As viewed in cross section the carcass 18 of the tire wheel 10 begins at the hub and extends as a continuous curve outwardly and thence inwardly as a continuous curve that merges into the tread.

The sidewalls 21 and 22 have a plurality of circumferentially spaced slots 32 that begin in the web portions 19 and 20 and extend through the sidewalls and terminates in the crown 28 of the tire carcass 18. As illustrated in FIG. 5 the slots 32 as opposite each other and with the respective ends of the slots ending into an annular shaped hole which is achieved by first drilling the slot ends and then connecting them. The respective diameters of the annular end holes is equal to the slot widths to minimize local stress concentrations. Additional slots or slits 34 are located within the sidewalls 19 and 20 between adjacent slots 32, however such slots or slits 34 extend from the crown and into the sidewall a distance that is close to the web portions but do not extend as far as slots 32 which terminate in the web portions. This arrangement of slots 32 and 34 create a series of beam members that provide a yielding and resiliency to the tire carcass 18 under load and impact conditions. By controlling the spacing of the slots and their termination points on the sidewall and web structure, it is easier to control the resiliency of the tire wheel. Additional slots 33 located between slots 32 and 34 are located within the crown and shoulder portion. The purpose here is to provide enough slots to help define the beam structure that provides for the controlled yielding and optimized strength. By increasing the number of slots in the outer radial sidewall portion of the tire one can optimize the strength of the material by maintaining the width between slots more consistent. The circumferential distance from the terminal end of one slot to an adjacent slot are substantially equal to further optimize the strength of the beam members in the tire carcass. As disclosed in the lower portion of FIG. 3 the respective beam structures in the sidewall 22 of the carcass closely adjacent to web portion 19 (designated "A") are thicker in cross section than those portions of the beam structures of the sidewall 22 (designated "B") adjacent to the shoulder 25. By so increasing the thicknesses adjacent to the hub section there is a corresponding reduction in the bending stress at this portion of the beam structure, thereby enhancing the performance of the non-pneumatic tire wheel.

The hub 12 along with the tire carcass 18 and the ring 29 defines a toroidal shape where toroidal is defined by its conventional meaning as a surface generated by the rotation of a plane closed curve about an axis lying in its plane and not intersecting it as a doughnut shape.

The hub 12 has a radially outwardly extending flange portion 36 that is recessed along its one outer side portion to receive a circumferentially extending shock absorber member 38 that is curvilinear in cross-section. The shock absorber 38 may be suitably connected to the hub 12. The curvilinear shape of the shock absorber may be S-shaped with the outer periphery having an annular ring 37 of elastomeric material adhered thereto. In addition, such shock absorber member 38 has a plurality of circumferentially spaced slots 39, 40 and 41 which together with the elastomeric ring 37 enhance the shock absorbing characteristics thereof. Slots 40 and 41 do not extend as far radially inwardly toward flange 36 as slots 39 to optimize the strength of the shock absorber 38. In the same manner slots 41 do not extend as far radially inwardly toward flange 36 as slots 40.

A modification of the shock absorber 38 is shown in FIG. 8 wherein the tire wheel 10 is identical to that described above, having annular carcass 18 mounted on axle 11 via annular hub 12 as in the first embodiment. The carcass 18 has the axially spaced web portions 19 and 20 with the spaced rigid sidewalls 21 and 22, and annular shoulders 24 and 25 that merge with the crown 28, ring 29 and tread 31. As in the first described embodiment, the hub 12 has a radially outwardly extending flange portion 36 that is suitably recessed along its one outer side portion to receive a circumferentially extending shock absorber 45 that is connected thereto via bolts 46. Shock absorber 45 has an annular radially outwardly extending circular flange 47, which flange 47 has suitably adhered or connected thereto along its outer side edges a pair of annular elastomeric members 49 and 50. The axial outer sides of the elastomeric members 49 and 50 are suitably connected or adhered to a pair of annular plates 52 and 53 respectively. The plates 52 and 53 have their outermost radial edges connected to an annular plate 54, which in turn is suitably connected to an annular resilient member or annular elastomeric member 56 to enhance the shock absorbing characteristics thereof.

It will be apparent that, although a specific embodiment and certain modifications of the invention have been described, the invention is not limited to the specifically illustrated and described constructions since variations may be made without departing from the principles of the invention.