Noncircular Gears: Geometry And Visualization MODEL Development

Report No. ARL-TR-5865
Authors: LTC David "Blake" Stringer, Ph.D.
Date/Pages: January 2012; 20 pages
Abstract: Circular gears are optimized to provide constant torque and speed ratio with low noise. In conventional automotive applications, a transmission provides the required power, torque, and speed settings using a finite arrangement of gear sets, which limits the range of transmission gear ratios, resulting in a loss of efficiency. However, other transmission configurations operate over a continuous range of gear ratios, providing a continuous range of output speeds while maintaining constant input shaft speed. Circular gears are not always practical for these configurations. One solution incorporates noncircular gears. The asymmetry of a noncircular gear pair results in instantaneously changing gear properties throughout gear rotation. This report presents a method for determining the required parameters to produce a noncircular gear pair of desired velocity and torque ratio distribution. Finally, to graphically depict the noncircular effects on gear motion, torque, and velocity distributions, a visualization model has been developed.
Distribution: Approved for public release
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Last Update / Reviewed: January 1, 2012