Patent ID: 6481305
Filing Date: 2002-11-19
Classification: F16H,Y10T

Abstract:
A roller screw comprising:a screw shaft having a spiral-shaped roller rolling groove formed in an outer peripheral surface thereof; a nut member having a spiral shaped load rolling groove formed in an inner peripheral surface thereof so as to correspond to said roller rolling groove; and a plurality of rollers to be arranged and stored between said roller rolling groove and said load rolling groove; wherein as said screw shaft is rotated with respect to said nut member, said nut member is allowed to reciprocate with respect to said screw shaft; wherein said plurality of roller$ includes a forward-motion load roller group the rollers of which are arranged in such a manner that the center lines thereof are set at a given angle with respect to the center line of said screw shaft, and a backward-motion load roller group the rollers of which are arranged in such a manner that the center lines thereof are set at an angle, which is different from said angle, with respect to the center line of said screw shaft; and wherein said forward-motion load roller group and said backward-motion load roller group are separated from each other within the nut, and wherein the winding numbers of said forward-motion load roller group and said backward-motion load roller group are set to be different from each other according to the ratio of axial-direction loads applied to said roller screw during the reciprocating motion thereof.