Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – Composite article making
Reexamination Certificate
1997-10-20
2001-10-16
Aftergut, Jeff H. (Department: 1733)
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
Composite article making
C264S046400, C264S261000, C152S246000, C152S248000, C152S249000, C156S113000
Reexamination Certificate
active
06303060
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of tires and wheel assemblies, and, more particularly, to non-deflatable tires and wheel assemblies for vehicles and equipment.
BACKGROUND
A familiar and aggravating problem with many conventional tires occurs when tires go flat. A common tire design utilizes air pressure to pressurize the tire or a tube within the tire. Though this design provides substantial ride cushioning and can carry a wide range of loads, a significant drawback is the risk of the tire going flat from air leakage, puncture of the tire or tube, or any other cause resulting in the escape of pressurized air within the tire or tube.
In an effort to address this problem, alternative tire designs have been developed which do not use pressurized air. To obtain ride cushioning and adequate load carrying capacity, these other designs rely upon the structure of the tire and/or rim upon which the tire is mounted and the features of the materials forming such structure.
A solid tire effectively eliminates the risk of a flat. However, a solid tire is unacceptably heavy and requires a substantially greater amount of material to make than a hollow tire, and is thus unacceptably expensive and often does not provide a cushioned ride. Therefore, a number of designs for nondeflatable tires employ a hollow structure which attempts to achieve high load-carrying capacities while still providing a cushioned ride. Examples of such tire designs are disclosed in U.S. Pat. No. 5,551,763 to Alsman, U.S. Pat. No. 1,438,604 to McClure, and U.S. Pat. No. 4,493,355 to Ippen et al.
Another problem often arising in conventional tire designs is the difficulty inherent in mounting the tire on a rim. It is obviously desirable for a tire to be securely mounted on a rim for safe operation of the tire. However, the very design employed to secure the tire on the rim often creates substantial difficulty in the assembly and disassembly of the tire and rim. Conventional non-deflatable tires (such as those described in the U.S. patents mentioned above) do not offer a design where the tire may be easily mounted on or removed from a rim.
Therefore, a need exists for a non-deflatable tire which can carry substantial loads while still providing a cushioned ride, which can be easily mounted and demounted from a rim, and which uses as little material as possible to minimize the weight of the tire and to save on the material costs. The invention as described herein provides such a tire.
SUMMARY OF THE INVENTION
The invention is a non-deflatable tire and method for making such a tire. In a preferred embodiment, the invention includes a toroid-shaped hollow insert surrounded by a flexible body of material forming a tire core or body and a tough outer skin forming a tread and sidewall surfaces. The hollow insert provides load carrying stiffness to the tire, and may be flexible enough to deform under loading and impact, thereby contributing to a cushioned ride. The composition and density of the flexible body of material surrounding the hollow insert also determines the flexibility of the tire and ride cushioning. The hollow insert has a flange which extends into the center of the toroid (toward what would be the central axis of the toroid). This flange may have holes formed therein for attachment of one or more rims to the flange via bolts. The flange may have protuberances formed therein to match protuberances or holes in the rim(s) on which the tire is mounted. Alternatively, the flange may have holes formed therein to match protuberances in the rim(s) on which the tire is mounted.
Torque and braking loads are transmitted from the axle on which the tire is mounted to the bolts in the rim(s) and flange of the insert, and then to the flexible body and treads of the tire. Where protuberances are employed in the flange and rim(s), these protuberances not only help in aligning the tire to the rim(s) during assembly, but also help to transmit torque and braking loads from the rim to the flange of the insert. The fit between the rim(s) and the tire is preferably an interference fit, enabling torque and braking loads to also be transmitted directly from the rim(s) to the tire (e.g., directly to the flexible body). To insure that the insert does not slip with respect to the flexible body surrounding the insert under torque and braking loads, the surface of the insert facing the flexible body may be treated to provide a bond between the flexible body and the insert, and may be ribbed for better engagement of the flexible body to the insert.
In a preferred embodiment, the flexible body is made of polyurethane, and more particularly, a polyurethane foam matrix formed of a combination of polyol and polyisocyanate. Also in a preferred embodiment, the outer tread and sidewalls of the tire are made of a tough, flexible polyurethane elastomer formed of a combination of polyol and polyisocyanate. Also in a preferred embodiment, the insert is made of high density polyethylene. The exact dimensions and cross-sectional shape of the insert and flexible body may affect the cushioning and flexibility properties of the tire, and may therefore be selected according to the intended uses of the tire.
REFERENCES:
patent: 362472 (1887-05-01), Warwick
patent: 727582 (1903-05-01), Brintnell
patent: 1438604 (1922-12-01), McClure
patent: 2338294 (1944-01-01), Maule
patent: 2673470 (1954-03-01), Cosmos
patent: 3445958 (1969-05-01), Johnson et al.
patent: 3646983 (1972-03-01), Lieshoud
patent: 3952786 (1976-04-01), Kreling et al.
patent: 4275782 (1981-06-01), McFarlane
patent: 4310042 (1982-01-01), Wyman et al.
patent: 4379104 (1983-04-01), Koorevaar
patent: 4493355 (1985-01-01), Ippen et al.
patent: 4514243 (1985-04-01), Moore et al.
patent: 4877071 (1989-10-01), Tanigawa et al.
patent: 5503466 (1996-04-01), Lew
patent: 5551763 (1996-09-01), Alsman
patent: 27 55 111 (1979-06-01), None
patent: 352-045-A (1990-01-01), None
patent: 11 005402 (1999-01-01), None
patent: 97/28013 (1997-08-01), None
Beer Roy C.
Lobo Pedro J.
Mizulo John T.
Sullivan James Patrick
Thomas James Michael
Aftergut Jeff H.
Ladas & Parry
Musser Barbara J.
Pacific Circle Technologies, Inc.
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