Improved Design of an Orthogonal-Axis-Type Precession Motion Ball Reducer

Abstract

To realize a no-backlash reducer for a small-size orthogonal-axis output, a novel design of a precession motion ball reducer is proposed. This reducer consists of a precession-motion-generating section, a motion direction converting section of the precession motion, and a reduced output-generating section. To avoid cutting tool interference, two types of distorted spatial circular grooves are located on the outer spherical surface of a precession rotor. Furthermore, the grooves of the reduced rotation generating section are profiled on the spherical surface at the output side of the precession motion rotor, which is different from the previous precession ball reducer. In this research, the equations for the groove loci of the precession motion generation, motion direction conversion, and reduced-rotation generation, which are located on the outer spherical surfaces, are proposed. The output rotating direction can be determined using the relationship between the input and output rotation angles of the precession motion direction converting groove. The prototype reducer is confirmed to smoothly rotate. Furthermore, at the hysteresis loss characteristic test, that is better than the backlash characteristic of a general orthogonal-axis output-type speed reducer with bevel gears.