Development of a low backlash Crown Reducer

In this paper, we describe a novel low backlash reducer using precessing crown gears. we call this mechanism Crown Reducer. The features of this reducer are low backlash, high reduction ratio, advantage in miniaturizing. These features greatly contribute to design various small mechanisms such as a finger joint of a robot hand. The crown gear pair is meshing in face to face, one acts as a rotor and the other as a stator. The rotor gear has N teeth and the hub is connected to the output shaft. The spokes of rotor gear are elastically deformed according to gears rolling. The stator gear fixed on a housing has N - 1 teeth (or N + 1). The meshing of crown gear pair with several shapes of rack tooth are simulated, and proper parameters of rack to improve high rigidity of teeth are calculated. Finally, backlash and minimum input torque to rotate are evaluated using a prototype reducer.