Patent ID: 9476433
Filing Date: 2016-10-25
CPC Classification: F15B

Claim Text:
1. A rotary actuator comprising: a tube having first and second hydraulic ports with through-holes penetrating a side wall of a tube body portion having first and second ends, the ports being separated a predetermined distance from each other and through which a fluid enters and is exhausted, the tube having a sleeve fixed inside the tube body portion between the first and second ends by a pin passing through a corresponding opening in the side wall of the tube, the sleeve includes an inner circumferential surface with a bearing pocket portion having a plurality of first spherical bearing pockets aligned in tube pocket rows with each tube pocket row helically aligned and equally spaced a first distance; a first end cap coupled with the first end of the tube; an axial rod having a second end cap disposed at the second end of the tube forming a platform to be rotated by the axial rod, the axial rod also having an outer circumferential surface with a helical groove portion and a smooth cylindrical body portion, the helical groove portion having at least three first spiral grooves with each being spaced a second distance, and the smooth cylindrical body portion being coupled with the first end cap; and a piston disposed between the tube body portion and the axial rod, the piston having a piston head and a slant groove body portion on an outer circumferential surface, wherein at least three second spiral grooves are formed on said outer circumferential surface of the slant groove body portion having a helical direction opposite the first spiral grooves and each being spaced equal to the first distance of the tube pocket rows of the inner circumferential surface of the tube for alignment therewith, and the piston also having an inner circumferential surface with at least three helically aligned rows of second spherical bearing pockets with each helical piston pocket row being spaced equal to the second distance of the first spiral grooves of the helical groove portion of the axial rod for alignment therewith; and wherein each of the first spherical bearing pockets of the bearing pocket portion on the inner circumferential surface of the sleeve fixed to the inside of the tube having a first bearing for rotation therein and along the correspondingly aligned second spiral groove of the piston, and each of the second spherical bearing pockets on the inner circumferential surface of the piston having a second piston bearing for rotation therein and along the correspondingly aligned first spiral groove of the helical groove portion of the axial rod.