Spin bearings have been invented as alternatives to such conventional rolling-element bearings as ball, spherical, needle, and roller bearings. Like a conventional bearing assembly, a spin-bearing assembly includes opposing complementary support members (more specifically, bearing races) spaced apart by rolling elements (more specifically, spin bearings, which correspond to ball, needle, or roller bearing elements).
Spin bearings can be made in a variety of sizes and shapes, with various numbers of contact surfaces that have compound convex and/or concave curvatures. The figure presents an example of a spin-bearing assembly that contains spin bearings that have convex contact surfaces and are shaped like an hourglass. A carrier spring partly encircles the waists of the spin bearings on their radially inner sides, keeping the spin bearings evenly spaced apart and gently biasing the spin bearings outward against the outer race. Two semicircular openings on the inner race are provided to enable the insertion or removal of spin bearings during assembly or disassembly, respectively.
What distinguishes spin-bearing assemblies is their unique rolling-element and bearing-race geometries, which afford advantages of load-bearing capacity, retention of alignment, and size, relative to the corresponding aspects of conventional bearings. By suitable choice of design parameters - especially the angles and the radii of curvature of contact surfaces of bearings and races, it is possible to reduce (relative to conventional designs) the contact stresses for bearing assemblies of a given size. Consequently, a spin-bearing assembly can be stronger than a ball-bearing assembly of the same size; or for a given load-bearing capacity, a spin-bearing assembly can be made smaller than a ball-bearing assembly.
Spin bearings are also superior to conventional bearings with respect to nature of the loads that they can bear. Both conventional and spin bearings can withstand radial (side) loads. However, unlike roller and needle bearings, spin bearings can withstand thrust (axial) loads as well. In comparison with an equivalent spherical-bearing assembly, a spin-bearing assembly has greater thrust capacity and/or is more compact, especially in the axial dimension. Unlike a spherical-bearing assembly, a spin-bearing assembly prevents the bearing races (and thus the structural members attached to them) from rocking and twisting with respect to each other; hence the spin-bearing assembly is more effective in stabilizing and positioning the structural members. In addition, spin bearings are superior to spherical bearings with respect to precision of motion. Finally, spin bearings do everything that tapered roller bearings can do, but in a simpler way and at lower cost.
This work was done by John M. Vranish ofGoddard Space Flight Center.
This invention has been patented by NASA (U.S. Patent No. 5,836,701). Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to
the Patent Counsel
Goddard Space Flight Center; (301) 286-7351
Refer to GSC-13679.