| 摘要 |
PROBLEM TO BE SOLVED: To reduce the linear movement amount of each part against the rotational movement amount inputted without lessening leads in a rotation/linear motion converting mechanism forming screw connection parts doubly. SOLUTION: In the planetary gear differential screw device 70, an outer nut 72, an inner nut 74, and a shaft 76 are screwed with ball screws 80, 82, and an outer ring gears 72c, 72d, planetary gears 74h, 74i, and sun gears 76b, 76c are meshed. When the outer nut 72 rotates, the inner nut 74 rotates at a reduced speed, and produces an axial movement amount corresponding to the rotation amount difference from the outer nut 72 and the lead of an outer ball screw 80. Furthermore, the shaft 76 produces an axial movement amount corresponding to the rotation amount of the decelerated inner nut 74, and the lead of an inner ball screw 82. Therefore, both the inner nut 74 and the shaft 76 produce restricted axial movement amounts. For this reason, the linear movement amount of each part against the rotational movement amount can be reduced without lessening the leads of the ball screws 80, 82, and upsizing of the engine and the like installed can be suppressed since the size variation in the planetary gear differential screw device 70 becomes smaller. COPYRIGHT: (C)2009,JPO&INPIT
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