HYDRODYNAMIC ROTARY ACTUATOR FOR CONVERTING LINEAR MOTION OF A PISTON IN A CYLINDER INTO ROTATION OF A CENTRAL SHAFT ACCORDING TO HYDRAULIC PRESSURE FLOW

摘要

PURPOSE: A rotary actuator is provided to improve the durability by distributing and transmitting power regardless of the direction of action of force with the balls and the ball roads, and to manufacture the rotary actuator easily by processing the linear or screw groove simply. CONSTITUTION: A rotary actuator comprises a body having a cylinder, a piston(20) combined with the cylinder of the body and composed of a shaft hole, a central shaft(30) combined with the shaft hole of the piston and supported by a bearing, a hydraulic line connected to the upper and lower parts of the cylinder divided by a piston head(21) in moving the piston head down, and a linear motion/ rotation converting unit converting linear motion of the piston into rotation of the central shaft. The linear motion/ rotation converting unit comprises plural screw ball roads(51) with the arc section in an expansion end(31) of the central shaft, a ball groove(52) formed in the lower part of the piston body, and a linear ball road(53) formed in the inner wall of the cylinder. A ball(54) inserted to the ball groove is engaged with the linear ball road or the screw ball road.