This tire design can be used where low vehicle energy consumption is required and for vehicles traveling over rough terrain.
The spring tire is made from helical springs, requires no air or rubber, and consumes nearly zero energy. The tire design provides greater traction in sandy and/or rocky soil, can operate in microgravity and under harsh conditions (vastly varying temperatures), and is non-pneumatic.
Like any tire, the spring tire is approximately a toroidal-shaped object intended to be mounted on a transportation wheel. Its basic function is also similar to a traditional tire, in that the spring tire contours to the surface on which it is driven to facilitate traction, and to reduce the transmission of vibration to the vehicle. The essential difference between other tires and the spring tire is the use of helical springs to support and/or distribute load. They are coiled wires that deform elastically under load with little energy loss.
This design is an advancement of the wire-mesh tire technology defined under U.S. Patent 3,568,748, entitled “Resilient Wheel.” The difference between the two tire technologies is the fundamental element used to create the wire mesh that forms the tire. The resilient wheel uses crimped wire mesh to form the tire, but the spring tire uses a coiled wire mesh. Under the weight of the vehicle, the tire is driven or towed, as well as steered. The springs within the tire passively contour to the terrain by flexing and moving with respect to each other.
There are three steps required to manufacture the spring tire. First, the springs are twisted together to form a rectangular sheet with length of the tire circumference. Second, the ends of the rectangular sheet of springs are interlaced to form a mesh cylinder. Third, one end of the mesh cylinder is collapsed and attached to the wheel, and the other end is flipped inside out, attaching it to the opposite end of the wheel.
The load-support springs are configured radially. This mitigates the pantographing of springs (rotation at their intersections). As a result, a relatively high mesh density may be used without neighboring springs. Elimination of pantographing also reduces friction forces.
The load support springs are also interwoven. This minimizes or eliminates the need for load distribution springs to hold the load support springs together. With fewer load distribution springs, the load support springs contour more freely and the overall tire weight is reduced. Cross-sections of the tire are approximately round, which distributes applied loads relatively uniformly. This reduces tires stresses and improves flotation and traction development in soft soil.
This work was done by Vivake M. Asnani of Glenn Research Center and Jim Benzing and Jim C. Kish of Goodyear Tire & Rubber Company. For more information, download the Technical Support Package (free white paper).
Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steve Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW-18466-1.
This Brief includes a Technical Support Package (TSP).
Spring Tire (reference LEW-18466-1) is currently available for download from the TSP library.
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